Lubricant reflow after laser heating in heat assisted magnetic recording

NASA Astrophysics Data System (ADS)

Wu, Haoyu; Mendez, Alejandro Rodriguez; Xiong, Shaomin; Bogy, David B.

2015-05-01

In heat assisted magnetic recording (HAMR) technology for hard disk drives, the media will be heated to about 500 °C during the writing process in order to reduce its magnetic coercivity and thus allow data writing with the magnetic head transducers. The traditional lubricants such as Z-dol and Z-tetraol may not be able to perform in such harsh heating conditions due to evaporation, decomposition and thermal depletion. However, some of the lubricant depletion can be recovered due to reflow after a period of time, which can help to reduce the chance of head disk interface failure. In this study, experiments of lubricant thermal depletion and reflow were performed using a HAMR test stage for a Z-tetraol type lubricant. Various lubricant depletion profiles were generated using different laser heating conditions. The lubricant reflow process after thermal depletion was monitored by use of an optical surface analyzer. In addition, a continuum based lubrication model was developed to simulate the lubricant reflow process. Reasonably good agreement between simulations and experiments was achieved.

Lubricant depletion under various laser heating conditions in Heat Assisted Magnetic Recording (HAMR)

NASA Astrophysics Data System (ADS)

Xiong, Shaomin; Wu, Haoyu; Bogy, David

2014-09-01

Heat assisted magnetic recording (HAMR) is expected to increase the storage areal density to more than 1 Tb/in2 in hard disk drives (HDDs). In this technology, a laser is used to heat the magnetic media to the Curie point (~400-600 °C) during the writing process. The lubricant on the top of a magnetic disk could evaporate and be depleted under the laser heating. The change of the lubricant can lead to instability of the flying slider and failure of the head-disk interface (HDI). In this study, a HAMR test stage is developed to study the lubricant thermal behavior. Various heating conditions are controlled for the study of the lubricant thermal depletion. The effects of laser heating repetitions and power levels on the lubricant depletion are investigated experimentally. The lubricant reflow behavior is discussed as well.

Laser optical disk position encoder with active heads

NASA Technical Reports Server (NTRS)

Osborne, Eric P.

1991-01-01

An angular position encoder that minimizes the effects of eccentricity and other misalignments between the disk and the read stations by employing heads with beam steering optics that actively track the disk in directions along the disk radius and normal to its surface is discussed. The device adapts features prevalent in optical disk technology to the application of angular position sensing.

Dynamic stability and slider-lubricant interactions in hard disk drives

NASA Astrophysics Data System (ADS)

Ambekar, Rohit Pradeep

2007-12-01

Hard disk drives (HDD) have played a significant role in the current information age and have become the backbone of storage. The soaring demand for mass data storage drives the necessity for increasing capacity of the drives and hence the areal density on the disks as well as the reliability of the HDD. To achieve greater areal density in hard disk drives, the flying height of the airbearing slider continually decreases. Different proximity forces and interactions influence the air bearing slider resulting in fly height modulation and instability. This poses several challenges to increasing the areal density (current goal is 2Tb/in.2) as well as making the head-disk interface (HDI) more reliable. Identifying and characterizing these forces or interactions has become important for achieving a stable fly height at proximity and realizing the goals of areal density and reliability. Several proximity forces or interactions influencing the slider are identified through the study of touchdown-takeoff hysteresis. Slider-lubricant interaction which causes meniscus force between the slider and disk as well as airbearing surface contamination seems to be the most important factor affecting stability and reliability at proximity. In addition, intermolecular forces and disk topography are identified as important factors. Disk-to-slider lubricant transfer leads to lubricant pickup on the slider and also causes depletion of lubricant on the disk, affecting stability and reliability of the HDI. Experimental and numerical investigation as well as a parametric study of the process of lubricant transfer has been done using a half-delubed disk. In the first part of this parametric study, dependence on the disk lubricant thickness, lubricant type and slider ABS design has been investigated. It is concluded that the lubricant transfer can occur without slider-disk contact and there can be more than one timescale associated with the transfer. Further, the transfer increases non-linearly with increasing disk lubricant thickness. Also, the transfer depends on the type of lubricant used, and is less for Ztetraol than for Zdol. The slider ABS design also plays an important role, and a few suggestions are made to improve the ABS design for better lubricant performance. In the second part of the parametric study, the effect of carbon overcoat, lubricant molecular weight and inclusion of X-1P and A20H on the slider-lubricant interactions is investigated using a half-delubed disk approach. Based on the results, it is concluded that there exists a critical head-disk clearance above which there is negligible slider-lubricant interaction. The interaction starts at this critical clearance and increases in intensity as the head-disk clearance is further decreased below the critical clearance. Using shear stress simulations and previously published work a theory is developed to support the experimental observations. The critical clearance depends on various HDI parameters and hence can be reduced through proper design of the interface. Comparison of critical clearance on CHx and CHxNy media indicates that presence of nitrogen is better for HDI as it reduces the critical clearance, which is found to increase with increasing lubricant molecular weight and in presence of additives X-1P and A20H. Further experiments maintaining a fixed slider-disk clearance suggest that two different mechanisms dominate the disk-to-slider and slider-to-disk lubricant transfer. One of the key factors influencing the slider stability at proximity is the disk topography, since it provides dynamic excitation to the low-flying sliders and strongly influences its dynamics. The effect of circumferential as well as radial disk topography is investigated using a new method to measure the 2-D (true) disk topography. Simulations using CMLAir dynamic simulator indicate a strong dependence on the circumferential roughness and waviness features as well as radial features, which have not been studied intensively till now. The simulations with 2-D disk topography are viewed as more realistic than the 1-D simulations. Further, it is also seen that the effect of the radial features can be reduced through effective ABS design. Finally, an attempt has been made to establish correlations between some of the proximity interactions as well as others which may affect the HDI reliability by creating a relational chart. Such an organization serves to give a bigger picture of the various efforts being made in the field of HDI reliability and link them together. From this chart, a causal relationship is suggested between the electrostatic, intermolecular and meniscus forces.

Optotech 5984 Drive Overview

NASA Astrophysics Data System (ADS)

Lee, Tzuo-Chang; Chen, Di

1987-01-01

We present in this paper an overview of Optotech's 5984 Optical Disk Drive. Key features such as the modulation code, the disk format, defect mapping scheme and the optical head and servo subsystem will be singled out for discussion. Description of Optotech's 5984 disk drive The Optotech 5984 optical disk drive is a write-once-read-mostly (WORM) rotating optical memory with 200 Megabyte capacity on each side of the disk. It has a 5 1/4 inch form factor that will fit into any personal computer full-height slot. The drive specification highlights are given in Table 1. A perspective view of the drive mechanical assembly is shown in Figure 1. The spindle that rotates the disk has a runout of less than 10 um. The rotational speed at 1200 revolutions per minute (rpm) is held to an accuracy of 10-3. The total angular tolerance from perfect perpendicular alignment between the rotating disk and the incident optical beam axis is held to less than 17 milliradians. The coarse seek is accomplished through a stepping motor driving the optical head with 1.3 milliseconds per step or 32 tracks per step. The analog channels including read/write, the phase lock loop and the servo loops for focus and track control are contained on one surface mount pc board while the digital circuitry that interfaces with the drive and the controller is on a separate pc board. A microprocessor 8039 is used to control the handshake and the sequence of R/W commands. A separate power board is used to provide power to the spindle and the stepping motors. In the following we will discuss some of the salient features in the drive and leave the details to three accompanying Optotech papers. These salient features are derived from a design that is driven by three major considerations. One is precise control of the one micron diameter laser spot to any desired location on the disk. The second consideration is effective management of media defects. Given the state of the art of the Te-based disk technology with an average raw defect density of approximately 10-5(compared to 10-draw error rate in high density magnetic hard disks), elaborate defect management tools are required to assure data integrity. The last consideration is, needless to say, low cost and high reliability.

Techniques for writing and reading data on an optical disk which include formation of holographic optical gratings in plural locations on the optical disk

NASA Technical Reports Server (NTRS)

Liu, Tsuen-Hsi (Inventor); Psaltis, Demetri (Inventor); Mok, Fai H. (Inventor); Zhou, Gan (Inventor)

2005-01-01

An optical memory for storing and/or reading data on an optical disk. The optical disk incorporates a material in which holographic gratings can be created, and subsequently detected, at plural locations within the disk by an electro-optical head. Creation and detection of holographic gratings with variable diffraction efficiency is possible with the electro-optical head. Multiple holographic gratings can also be created at each one of the plural locations via a beam of light which has a different wavelength or point of focus. These data elements can be read by the electro-optical head using a beam of light sequentially varied in wavelength or point of focus to correspond to the multiple holographic gratings to be recorded.

The Cycles of Gaseous Baryons between the Disk and Halo

NASA Astrophysics Data System (ADS)

Zheng, Yong

2018-01-01

The disks of galaxies closely interact with the circumgalactic medium (CGM) through the disk-halo (D/H) interface. The disks grow by inflows from the CGM, while the CGM is enriched, stirred, and heated by outflows from the disks. Recent years have seen great breakthroughs in observations of inflows and outflows at the D/H interface; however, inflow detections are still rare and the structure of the D/H interface is unclear. My thesis work includes searching for inflows and studying the multiphase gas at the D/H interface, and building my expertise in both UV spectroscopy and HI 21cm observations.I will first show HST/COS observations of gas inflows detected in Si IV absorption lines at M33’s D/H interface (Zheng et al. 2017a); this is among the first to unambiguously reveal the existence of disk-wide galactic inflows. The detection of Si IV-bearing inflows indicates that baryons are efficiently recycled between the disk and halo, mostly consistent with a galactic fountain scenario. Then I will present a 3-dimensional kinematic model of the Milky Way (MW)’s D/H interface. I will show that beyond the MW’s D/H interface, there is a significant amount of baryons in the MW’s CGM moving at low velocities (|vlsr|<100 km/s; Zheng et al. 2015, Zheng et al. 2017c). Current MW’s CGM mass estimates suffer from an inside-out observational bias: local observers miss more than half of the gas mass in the MW’s CGM that is blocked out in high-velocity focused studies.

Optimization of Smart Structure for Improving Servo Performance of Hard Disk Drive

NASA Astrophysics Data System (ADS)

Kajiwara, Itsuro; Takahashi, Masafumi; Arisaka, Toshihiro

Head positioning accuracy of the hard disk drive should be improved to meet today's increasing performance demands. Vibration suppression of the arm in the hard disk drive is very important to enhance the servo bandwidth of the head positioning system. In this study, smart structure technology is introduced into the hard disk drive to suppress the vibration of the head actuator. It has been expected that the smart structure technology will contribute to the development of small and light-weight mechatronics devices with the required performance. First, modeling of the system is conducted with finite element method and modal analysis. Next, the actuator location and the control system are simultaneously optimized using genetic algorithm. Vibration control effect with the proposed vibration control mechanisms has been evaluated by some simulations.

Stability of a chemically active floating disk

NASA Astrophysics Data System (ADS)

Vandadi, Vahid; Jafari Kang, Saeed; Rothstein, Jonathan; Masoud, Hassan

2017-11-01

We theoretically study the translational stability of a chemically active disk located at a flat liquid-gas interface. The initially immobile circular disk uniformly releases an interface-active agent that locally changes the surface tension and is insoluble in the bulk. If left unperturbed, the stationary disk remains motionless as the agent is discharged. Neglecting the inertial effects, we numerically test whether a perturbation in the translational velocity of the disk can lead to its spontaneous and self-sustained motion. Such a perturbation gives rise to an asymmetric distribution of the released factor that could trigger and sustain the Marangoni propulsion of the disk. An implicit Fourier-Chebyshev spectral method is employed to solve the advection-diffusion equation for the concentration of the active agent. The solution, given a linear equation of state for the surface tension, provides the shear stress distribution at the interface. This and the no-slip condition on the wetted surface of the disk are then used at each time step to semi-analytically determine the Stokes flow in the semi-infinite liquid layer. Overall, the findings of our investigation pave the way for pinpointing the conditions under which interface-bound active particles become dynamically unstable.

Nanoscale modeling for ultrathin liquid films: Spreading and coupled layering

NASA Astrophysics Data System (ADS)

Phillips, David Michael

The hard disk drive (HDD) industry is currently experiencing a compound annual growth rate of 100% for the areal density. Current production drives have an areal density of 80 Gbit in-2, and drives with an areal density of 100 Gbit in-2 have been recently demonstrated. While much of this growth has been fueled by the development of new read/write heads, some of this gain was achieved by reducing the spacing between the heads and the magnetic media. This in turn reduces the spacing at the head-disk interface (HDI). The HDI in a HDD system consists of a slider, which contains the read/write heads, flying over the disk surface on an air bearing. The current designed separation distance, or fly height, is less than 10 nm. This spacing is expected to reduce to a mere 5 nm within the next few years. With the reduced fly height, intermittent contacts at the HDI become more probable. Only a thin lubricant film of perfluoropolyether (PFPE) and a sputtered carbon overcoat on the disk surface protect the slider and the stored data from mechanical and thermal damage. The PFPE film is quite thin, with a thickness of less than 2 nm or about a monolayer of molecules. During an HDI contact, the PFPE film is considered sacrificial and is often depleted in the contact area. In order to maintain adequate protection for the disk surface, PFPE molecules from the surrounding film must replenish the depleted area. This replenishment ability directly opposes the requirement that the PFPE film must not spin-off of the disk surface due to the disk rotation rate, which is as high as 10,000 RPM in current drives. To balance the PFPE films to sufficiently meet both requirements, HDD manufacturers functionalized the endgroups of the PFPE molecules to allow some portion of the lubricant film to reversibly bond with the disk overcoat. The result is a lubricant film that has a slower replenishment but does not spin-off. The work presented here focuses on the replenishment ability of thin films of liquid PFPE. The experimental analogue of replenishment is the one-dimensional spreading analysis. PFPEs with functional endgroups demonstrated coupled molecular layering and dewetting phenomena during the spreading analysis, while PFPEs with nonfunctional endgroups did not. All of the PFPE thin films spread via a diffusive process and had diffusion coefficients that depended on the local film thickness. A theoretical analysis is presented here for both the governing equation and the disjoining pressure driving force for the PFPE thin film spreading. For PFPEs with non-functional endgroups, a reasonable analysis is performed on the diffusion coefficient for two classes of film: submonolayer and multilayer. The diffusion coefficient of PFPEs with functional endgroups are qualitatively linked to the gradient of the film disjoining pressure. To augment this theory, both lattice-based and off-lattice Monte Carlo simulations are conducted for PFPE film models. The lattice-based model shows the existence of a critical functional endgroup interaction strength. It is also used to study the break-up of molecular layers for a spreading film via a fractal analysis. The off-lattice model is used to calculate the anisotropic pressure tensor for the model PFPE thin film and subsequently the film disjoining pressure. The model also qualitatively analyzes of the self diffusion in the film.

Study on compensation algorithm of head skew in hard disk drives

NASA Astrophysics Data System (ADS)

Xiao, Yong; Ge, Xiaoyu; Sun, Jingna; Wang, Xiaoyan

2011-10-01

In hard disk drives (HDDs), head skew among multiple heads is pre-calibrated during manufacturing process. In real applications with high capacity of storage, the head stack may be tilted due to environmental change, resulting in additional head skew errors from outer diameter (OD) to inner diameter (ID). In case these errors are below the preset threshold for power on recalibration, the current strategy may not be aware, and drive performance under severe environment will be degraded. In this paper, in-the-field compensation of small DC head skew variation across stroke is proposed, where a zone table has been equipped. Test results demonstrating its effectiveness to reduce observer error and to enhance drive performance via accurate prediction of DC head skew are provided.

Technique of Axillary Use of a Combat Ready Clamp to Stop Junctional Bleeding

DTIC Science & Technology

2013-01-01

compressed parallel to—but not on—the clavicle (Fig. 4). 5. Adjust the horizontal arm length by using its locking pin. 6. Adjust the vertical arm by...arm adjustment for square disk head contact atop the target. Fig. 4. Placing the square disk head atop the target, parallel to—but not on—the clavicle

Time-resolved scanning Kerr microscopy of flux beam formation in hard disk write heads

NASA Astrophysics Data System (ADS)

Valkass, Robert A. J.; Spicer, Timothy M.; Burgos Parra, Erick; Hicken, Robert J.; Bashir, Muhammad A.; Gubbins, Mark A.; Czoschke, Peter J.; Lopusnik, Radek

2016-06-01

To meet growing data storage needs, the density of data stored on hard disk drives must increase. In pursuit of this aim, the magnetodynamics of the hard disk write head must be characterized and understood, particularly the process of "flux beaming." In this study, seven different configurations of perpendicular magnetic recording (PMR) write heads were imaged using time-resolved scanning Kerr microscopy, revealing their detailed dynamic magnetic state during the write process. It was found that the precise position and number of driving coils can significantly alter the formation of flux beams during the write process. These results are applicable to the design and understanding of current PMR and next-generation heat-assisted magnetic recording devices, as well as being relevant to other magnetic devices.

Innovative opto-mechanical design of a laser head for compact thin-disk

NASA Astrophysics Data System (ADS)

Macúchová, Karolina; Smrž, Martin; Řeháková, Martina; Mocek, Tomáš

2016-11-01

We present recent progress in design of innovative versatile laser head for lasers based on thin-disk architecture which are being constructed at the HiLASE centre of the IOP in the Czech Republic. Concept of thin-disk laser technology allows construction of lasers providing excellent beam quality with high average output power and optical efficiency. Our newly designed thin-disk carrier and pump module comes from optical scheme consisting of a parabolic mirror and roof mirrors proposed in 90's. However, mechanical parts and a cooling system were in-house simplified and tailor-made to medium power lasers since no suitable setup was commercially available. Proposed opto-mechanical design is based on stable yet easily adjustable mechanics. The only water nozzle-cooled component is a room-temperature-operated thindisk mounted on a special cooling finger. Cooling of pump optics was replaced by heat conductive transfer from mirrors made of special Al alloy to a massive brass baseplate. Such mirrors are easy to manufacture and very cheap. Presented laser head was manufactured and tested in construction of Er and Yb doped disk lasers. Details of the latest design will be presented.

DISK PUMP FEASIBILITY INVESTIGATION,

DTIC Science & Technology

system as an inducer and/or mainstage pump for liquid rocket applications. This investigation consisted of the analysis, design, and test of a disk...pumping action is a function of the viscous properties of the pumped fluid. (2) The pump does not require the conventional pump lifting forces. ( 3 ...with no apparent head deterioration. The representative maximum suction specific speed at a 3 % head drop was never reached. The pump demonstrated

Disk repositioning surgery of the temporomandibular joint with bioabsorbable anchor.

PubMed

Spallaccia, Fabrizio; Rivaroli, Andrea; Basile, Emanuela; Cascone, Piero

2013-01-01

The most common temporomandibular joint (TMJ) pathologic disease is anterior-medial displacement of the articular disk, which can lead to TMJ-related symptoms.The indication for disk repositioning surgery is irreversible TMJ damage associated with temporomandibular pain. We describe a surgical technique using a preauricular approach with a high condylectomy to reshape the condylar head. The disk is anchored with a bioabsorbable microanchor (Mitek Microfix QuickAnchor Plus 1.3) to the lateral aspect of the condylar head. The anchor is linked with a 3.0 Ethibond absorbable suture to fix the posterolateral side of the disk above the condyle.The aims of this surgery were to alleviate temporomandibular pain, headaches, and neck pain and to restore good jaw mobility. In the long term, we achieved these objectives through restoration of the physiological position and function of the disk and the lower articular compartment.In our opinion, the bioabsorbable anchor is the best choice for this type of surgery because it ensures the stability of the restored disk position and leaves no artifacts in the long term that might impede follow-up with magnetic resonance imaging.

Time-resolved scanning Kerr microscopy of flux beam formation in hard disk write heads

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

Valkass, Robert A. J., E-mail: rajv202@ex.ac.uk; Spicer, Timothy M.; Burgos Parra, Erick

To meet growing data storage needs, the density of data stored on hard disk drives must increase. In pursuit of this aim, the magnetodynamics of the hard disk write head must be characterized and understood, particularly the process of “flux beaming.” In this study, seven different configurations of perpendicular magnetic recording (PMR) write heads were imaged using time-resolved scanning Kerr microscopy, revealing their detailed dynamic magnetic state during the write process. It was found that the precise position and number of driving coils can significantly alter the formation of flux beams during the write process. These results are applicable tomore » the design and understanding of current PMR and next-generation heat-assisted magnetic recording devices, as well as being relevant to other magnetic devices.« less

Rotary Drum Separator and Pump for the Sabatier Carbon Dioxide Reduction System

NASA Technical Reports Server (NTRS)

Holder, Don; Fort, James; Barone, Michael; Murdoch, Karen

2005-01-01

A trade study conducted in 2001 selected a rotary disk separator as the best candidate to meet the requirements for an International Space Station (ISS) Carbon Dioxide Reduction Assembly (CRA). The selected technology must provide micro-gravity gasfliquid separation and pump the liquid from 10 psia at the gasfliquid interface to 18 psia at the wastewater bus storage tank. The rotary disk concept, which has pedigree in other systems currently being built for installation on the ISS, failed to achieve the required pumping head within the allotted power. The separator discussed in this paper is a new design that was tested to determine compliance with performance requirements in the CRA. The drum separator and pump @SP) design is similar to the Oxygen Generator Assembly (OGA) Rotary Separator Accumulator (RSA) in that it has a rotating assembly inside a stationary housing driven by a integral internal motor. The innovation of the DSP is the drum shaped rotating assembly that acts as the accumulator and also pumps the liquid at much less power than its predecessors. In the CRA application, the separator will rotate at slow speed while accumulating water. Once full, the separator will increase speed to generate sufficient head to pump the water to the wastewater bus. A proof-of- concept (POC) separator has been designed, fabricated and tested to assess the separation efficiency and pumping head of the design. This proof-of-concept item was flown aboard the KC135 to evaluate the effectiveness of the separator in a microgravity environment. This separator design has exceeded all of the performance requirements. The next step in the separator development is to integrate it into the Sabatier Carbon Dioxide Reduction System. This will be done with the Sabatier Engineering Development Unit at the Johnson Space Center.

Synthesis of Ultrathin ta-C Films by Twist-Filtered Cathodic Arc Carbon Plasmas

DTIC Science & Technology

2001-04-01

system. Ultrathin tetrahedral amorphous carbon (ta-C) films have been deposited on 6 inch wafers. Film properties have been investigated with respect to...Diamondlike films are characterized by an outstanding combination of advantageous properties : they can be very hard, tough, super-smooth, chemically...5 nm) hard carbon films are being used as protective overcoats on hard disks and read-write heads. The tribological properties of the head-disk

airborne data analysis/monitor system

NASA Technical Reports Server (NTRS)

Stephison, D. B.

1981-01-01

An Airborne Data Analysis/Monitor System (ADAMS), a ROLM 1666 computer based system installed onboard test airplanes used during experimental testing is evaluated. In addition to the 1666 computer, the ADAMS hardware includes a DDC System 90 fixed head disk and a Miltape DD400 floppy disk. Boeing designed a DMA interface to the data acquisition system and an intelligent terminal to reduce system overhead and simplify operator commands. The ADAMS software includes RMX/RTOS and both ROLM FORTRAN and assembly language are used. The ADAMS provides real time displays that enable onboard test engineers to make rapid decisions about test conduct thus reducing the cost and time required to certify new model airplanes, and improved the quality of data derived from the test, leading to more rapid development of improvements resulting in quieter, safer, and more efficient airplanes. The availability of airborne data processing removes most of the weather and geographical restrictions imposed by telemetered flight test data systems. A data base is maintained to describe the airplane, the data acquisition system, the type of testing, and the conditions under which the test is performed.

An optical disk archive for a data base management system

NASA Technical Reports Server (NTRS)

Thomas, Douglas T.

1985-01-01

An overview is given of a data base management system that can catalog and archive data at rates up to 50M bits/sec. Emphasis is on the laser disk system that is used for the archive. All key components in the system (3 Vax 11/780s, a SEL 32/2750, a high speed communication interface, and the optical disk) are interfaced to a 100M bits/sec 16-port fiber optic bus to achieve the high data rates. The basic data unit is an autonomous data packet. Each packet contains a primary and secondary header and can be up to a million bits in length. The data packets are recorded on the optical disk at the same time the packet headers are being used by the relational data base management software ORACLE to create a directory independent of the packet recording process. The user then interfaces to the VAX that contains the directory for a quick-look scan or retrieval of the packet(s). The total system functions are distributed between the VAX and the SEL. The optical disk unit records the data with an argon laser at 100M bits/sec from its buffer, which is interfaced to the fiber optic bus. The same laser is used in the read cycle by reducing the laser power. Additional information is given in the form of outlines, charts, and diagrams.

RAID-2: Design and implementation of a large scale disk array controller

NASA Technical Reports Server (NTRS)

Katz, R. H.; Chen, P. M.; Drapeau, A. L.; Lee, E. K.; Lutz, K.; Miller, E. L.; Seshan, S.; Patterson, D. A.

1992-01-01

We describe the implementation of a large scale disk array controller and subsystem incorporating over 100 high performance 3.5 inch disk drives. It is designed to provide 40 MB/s sustained performance and 40 GB capacity in three 19 inch racks. The array controller forms an integral part of a file server that attaches to a Gb/s local area network. The controller implements a high bandwidth interconnect between an interleaved memory, an XOR calculation engine, the network interface (HIPPI), and the disk interfaces (SCSI). The system is now functionally operational, and we are tuning its performance. We review the design decisions, history, and lessons learned from this three year university implementation effort to construct a truly large scale system assembly.

Improvement of thermal management in the composite Yb:YAG/YAG thin-disk laser

NASA Astrophysics Data System (ADS)

Kuznetsov, I. I.; Mukhin, I. B.; Palashov, O. V.

2016-04-01

To improve the thermal management in the composite Yb:YAG/YAG thin-disk laser a new design of laser head is developed. Thermal-induced phase distortions, small signal gain and lasing in the upgraded laser head are investigated and compared with previously published results. A substantial decrease of the thermal lens optical power and phase aberrations and increase of the laser slope efficiency are observed. A continuous-wave laser with 440 W average power and 44% slope efficiency is constructed.

Interfacing a high performance disk array file server to a Gigabit LAN

NASA Technical Reports Server (NTRS)

Seshan, Srinivasan; Katz, Randy H.

1993-01-01

Our previous prototype, RAID-1, identified several bottlenecks in typical file server architectures. The most important bottleneck was the lack of a high-bandwidth path between disk, memory, and the network. Workstation servers, such as the Sun-4/280, have very slow access to peripherals on busses far from the CPU. For the RAID-2 system, we addressed this problem by designing a crossbar interconnect, Xbus board, that provides a 40MB/s path between disk, memory, and the network interfaces. However, this interconnect does not provide the system CPU with low latency access to control the various interfaces. To provide a high data rate to clients on the network, we were forced to carefully and efficiently design the network software. A block diagram of the system hardware architecture is given. In the following subsections, we describe pieces of the RAID-2 file server hardware that had a significant impact on the design of the network interface.

LOCAL TADPOLE GALAXIES

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

Elmegreen, Debra Meloy; Putko, Joseph; Dewberry, Janosz

2012-05-10

Tadpole galaxies have a giant star-forming region at the end of an elongated intensity distribution. Here we use Sloan Digital Sky Survey data to determine the ages, masses, and surface densities of the heads and tails in 14 local tadpoles selected from the Kiso and Michigan surveys of UV-bright galaxies, and we compare them to tadpoles previously studied in the Hubble Ultra Deep Field. The young stellar mass in the head scales linearly with rest-frame galaxy luminosity, ranging from {approx}10{sup 5} M{sub Sun} at galaxy absolute magnitude U = -13 mag to 10{sup 9} M{sub Sun} at U = -20more » mag. The corresponding head surface density increases from several M {sub Sun} pc{sup -2} locally to 10-100 M{sub Sun} pc{sup -2} at high redshift, and the star formation rate (SFR) per unit area in the head increases from {approx}0.01 M{sub Sun} yr{sup -1} kpc{sup -2} locally to {approx}1 M{sub Sun} yr{sup -1} kpc{sup -2} at high z. These local values are normal for star-forming regions, and the increases with redshift are consistent with other cosmological SFRs, most likely reflecting an increase in gas abundance. The tails in the local sample look like bulge-free galaxy disks. Their photometric ages decrease from several Gyr to several hundred Myr with increasing z, and their surface densities are more constant than the surface densities of the heads. The far-outer intensity profiles in the local sample are symmetric and exponential. We suggest that most local tadpoles are bulge-free galaxy disks with lopsided star formation, perhaps from environmental effects such as ram pressure or disk impacts, or from a Jeans length comparable to half the disk size.« less

Modeling of axial vibrational control technique for CdTe VGF crystal growth under controlled cadmium partial pressure

NASA Astrophysics Data System (ADS)

Avetissov, I.; Kostikov, V.; Meshkov, V.; Sukhanova, E.; Grishechkin, M.; Belov, S.; Sadovskiy, A.

2014-01-01

A VGF growth setup assisted by axial vibrations of baffle submerged into CdTe melt with controlled Cd partial pressure was designed. An influence of baffle shape on flow velocity map, temperature distribution in CdTe melt and interface shape of growing crystal was analyzed by numerical simulation and physical modeling. To produce the desirable shape of crystal melt interface we slant under different angles vertical generatrix in a cylindrical disk and made chasing on faceplates of a disk. It was ascertained that a disk with conical generatrix formed more intensive convective flows from a faceplate with larger diameter. It was shown that at CdTe VGF crystal growth rate about 10 mm/h application of AVC technique made it possible to produce convex interface for 2 in. crystal diameter.

Magnetic Field Sensors Based on Giant Magnetoresistance (GMR) Technology: Applications in Electrical Current Sensing

PubMed Central

Reig, Candid; Cubells-Beltran, María-Dolores; Muñoz, Diego Ramírez

2009-01-01

The 2007 Nobel Prize in Physics can be understood as a global recognition to the rapid development of the Giant Magnetoresistance (GMR), from both the physics and engineering points of view. Behind the utilization of GMR structures as read heads for massive storage magnetic hard disks, important applications as solid state magnetic sensors have emerged. Low cost, compatibility with standard CMOS technologies and high sensitivity are common advantages of these sensors. This way, they have been successfully applied in a lot different environments. In this work, we are trying to collect the Spanish contributions to the progress of the research related to the GMR based sensors covering, among other subjects, the applications, the sensor design, the modelling and the electronic interfaces, focusing on electrical current sensing applications. PMID:22408486

OT1_mputman_1: ASCII: All Sky observations of Galactic CII

NASA Astrophysics Data System (ADS)

Putman, M.

2010-07-01

The Milky Way and other galaxies require a significant source of ongoing star formation fuel to explain their star formation histories. A new ubiquitous population of discrete, cold clouds have recently been discovered at the disk-halo interface of our Galaxy that could potentially provide this source of fuel. We propose to observe a small sample of these disk-halo clouds with HIFI to determine if the level of [CII] emission detected suggests they represent the cooling of warm clouds at the interface between the star forming disk and halo. These cooling clouds are predicted by simulations of warm clouds moving into the disk-halo interface region. We target 5 clouds in this proposal for which we have high resolution HI maps and can observe the densest core of the cloud. The results of our observations will also be used to interpret the surprisingly high detections of [CII] for low HI column density clouds in the Galactic Plane by the GOT C+ Key Program by extending the clouds probed to high latitude environments.

Water Powered Tools

NASA Technical Reports Server (NTRS)

1976-01-01

Space Spin-Offs, Inc. under a contract with Lewis Research Center and Marshall Space Flight Center produced a new water-powered saw that cuts through concrete and steel plate reducing danger of explosion or electric shock in rescue and other operations. In prototype unit efficient water-powered turbine drives an 8 inch diameter grinding disk at 6,600 rpm. Exhaust water cools disk and workpiece quenching any sparks produced by cutting head. At maximum power, tool easily cuts through quarter inch steel plate. Adapter heads for chain saws, impact wrenches, heavy duty drills, and power hack saws can be fitted.

The User Interface: How Does Your Product Look and Feel?

ERIC Educational Resources Information Center

Strukhoff, Roger

1987-01-01

Discusses the importance of user cordial interfaces to the successful marketing of optical data disk products, and describes features of several online systems. The topics discussed include full text searching, indexed searching, menu driven interfaces, natural language interfaces, computer graphics, and possible future developments. (CLB)

Research Studies on Advanced Optical Module/Head Designs for Optical Disk Recording Devices

NASA Technical Reports Server (NTRS)

Burke, James J.; Seery, Bernard D.

1993-01-01

The Annual Report of the Optical Data Storage Center of the University of Arizona is presented. Summary reports on continuing projects are presented. Research areas include: magneto-optic media, optical heads, and signal processing.

COLLABORATIVE RESEARCH AND DEVELOPMENT (CR&D) Delivery Order 0068: Anti-fretting Coatings Research and Development

DTIC Science & Technology

2008-02-01

reduction in fatigue strength [10]. One common mitigation strategy to the fretting wear/fatigue problem in titanium alloy compressor blades is to...inter-metallic fretting wear between Ti6Al4V ( Titanium , 6% Aluminum, 4% Vanadium) and cold-sprayed, commercially pure nickel coatings. The results...fretting in an aircraft turbine engine is in the compressor section at the blade /disk interface. The blade /disk interface, also known as the

A high-speed, large-capacity, 'jukebox' optical disk system

NASA Technical Reports Server (NTRS)

Ammon, G. J.; Calabria, J. A.; Thomas, D. T.

1985-01-01

Two optical disk 'jukebox' mass storage systems which provide access to any data in a store of 10 to the 13th bits (1250G bytes) within six seconds have been developed. The optical disk jukebox system is divided into two units, including a hardware/software controller and a disk drive. The controller provides flexibility and adaptability, through a ROM-based microcode-driven data processor and a ROM-based software-driven control processor. The cartridge storage module contains 125 optical disks housed in protective cartridges. Attention is given to a conceptual view of the disk drive unit, the NASA optical disk system, the NASA database management system configuration, the NASA optical disk system interface, and an open systems interconnect reference model.

Ignition of a Combustible Atmosphere by Incandescent Carbon Wear Particles

NASA Technical Reports Server (NTRS)

Buckley, Donald H.; Swikert, Max A.; Johnson, Robert L.

1960-01-01

A study was made to determine whether carbon wear particles from carbon elements in sliding contact with a metal surface were sufficiently hot to cause ignition of a combustible atmosphere. In some machinery, electric potential differences and currents may appear at the carbon-metal interface. For this reason the effect of these voltages and currents on the ability of carbon wear particles to cause ignition was evaluated. The test specimens used in the investigation were carbon vanes taken from a fuel pump and flat 21-inch-diameter 2 metal disks (440-C stainless steel) representing the pump housing. During each experiment a vane was loaded against a disk with a 0.5-pound force, and the disk was rotated to give a surface speed of 3140 feet per minute. The chamber of the apparatus that housed the vane and the disk was filled with a combustible mixture of air and propane. Various voltages and amperages were applied across the vane-disk interface. Experiments were conducted at temperatures of 75, 350, 400, and 450 F. Fires were produced by incandescent carbon wear particles obtained at conditions of electric potential as low as 106 volts and 0.3 ampere at 400 F. Ignitions were obtained only with carbon wear particles produced with an electric potential across the carbon-vane-disk interface. No ignitions were obtained with carbon wear particles produced in the absence of this potential; also, the potential difference produced no ignitions in the absence of carbon wear particles. A film supplement showing ignition by incandescent wear particles is available.

Spitzer Spectroscopy of the Transition Object TW Hya

DTIC Science & Technology

2010-02-24

results bear on our understanding of the evolutionary state of the TW Hya disk . Subject headings: (stars:) circumstellar matter — (stars:) planetary systems... protoplanetary disks — stars: pre-main sequence — (stars: individual) TW Hya 1. Introduction Spectroscopy with the Spitzer Space Telescope has...region of the disk . (2) If a planet has formed with a mass sufficient to open a gap (∼ 1MJ), gas will be cleared in the vicinity of its orbit, but gap

A Methodolgy, Based on Analytical Modeling, for the Design of Parallel and Distributed Architectures for Relational Database Query Processors.

DTIC Science & Technology

1987-12-01

Application Programs Intelligent Disk Database Controller Manangement System Operating System Host .1’ I% Figure 2. Intelligent Disk Controller Application...8217. /- - • Database Control -% Manangement System Disk Data Controller Application Programs Operating Host I"" Figure 5. Processor-Per- Head data. Therefore, the...However. these ad- ditional properties have been proven in classical set and relation theory [75]. These additional properties are described here

A new servo method using servo layer and transverse MR head for submicron track servo on hard computer disks

NASA Astrophysics Data System (ADS)

Tan, Baolin; Mapps, Desmond J.; Pan, Genhua; Robinson, Paul

1996-03-01

A disk with a data, servo and isolation layer has been fabricated with the data layer magnetized along the circumferential direction. The servo layer was recorded with servo pattern magnetized along the radial direction. A continuous servo signal is obtained and the servo does not occupy any data area. In this new method, the servo and data bits can share media surface area on the disk without interference. Track following on 0.7 μm tracks has been demonstrated using the new servo method on longitudinal rigid disks.

The Galley Parallel File System

NASA Technical Reports Server (NTRS)

Nieuwejaar, Nils; Kotz, David

1996-01-01

Most current multiprocessor file systems are designed to use multiple disks in parallel, using the high aggregate bandwidth to meet the growing I/0 requirements of parallel scientific applications. Many multiprocessor file systems provide applications with a conventional Unix-like interface, allowing the application to access multiple disks transparently. This interface conceals the parallelism within the file system, increasing the ease of programmability, but making it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. In addition to providing an insufficient interface, most current multiprocessor file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic scientific multiprocessor workloads. We discuss Galley's file structure and application interface, as well as the performance advantages offered by that interface.

A novel device for head gesture measurement system in combination with eye-controlled human machine interface

NASA Astrophysics Data System (ADS)

Lin, Chern-Sheng; Ho, Chien-Wa; Chang, Kai-Chieh; Hung, San-Shan; Shei, Hung-Jung; Yeh, Mau-Shiun

2006-06-01

This study describes the design and combination of an eye-controlled and a head-controlled human-machine interface system. This system is a highly effective human-machine interface, detecting head movement by changing positions and numbers of light sources on the head. When the users utilize the head-mounted display to browse a computer screen, the system will catch the images of the user's eyes with CCD cameras, which can also measure the angle and position of the light sources. In the eye-tracking system, the program in the computer will locate each center point of the pupils in the images, and record the information on moving traces and pupil diameters. In the head gesture measurement system, the user wears a double-source eyeglass frame, so the system catches images of the user's head by using a CCD camera in front of the user. The computer program will locate the center point of the head, transferring it to the screen coordinates, and then the user can control the cursor by head motions. We combine the eye-controlled and head-controlled human-machine interface system for the virtual reality applications.

NSSDC activities with 12-inch optical disk drives

NASA Technical Reports Server (NTRS)

Lowrey, Barbara E.; Lopez-Swafford, Brian

1986-01-01

The development status of optical-disk data transfer and storage technology at the National Space Science Data Center (NSSDC) is surveyed. The aim of the R&D program is to facilitate the exchange of large volumes of data. Current efforts focus on a 12-inch 1-Gbyte write-once/read-many disk and a disk drive which interfaces with VAX/VMS computer systems. The history of disk development at NSSDC is traced; the results of integration and performance tests are summarized; the operating principles of the 12-inch system are explained and illustrated with diagrams; and the need for greater standardization is indicated.

A well-posed numerical method to track isolated conformal map singularities in Hele-Shaw flow

NASA Technical Reports Server (NTRS)

Baker, Gregory; Siegel, Michael; Tanveer, Saleh

1995-01-01

We present a new numerical method for calculating an evolving 2D Hele-Shaw interface when surface tension effects are neglected. In the case where the flow is directed from the less viscous fluid into the more viscous fluid, the motion of the interface is ill-posed; small deviations in the initial condition will produce significant changes in the ensuing motion. This situation is disastrous for numerical computation, as small round-off errors can quickly lead to large inaccuracies in the computed solution. Our method of computation is most easily formulated using a conformal map from the fluid domain into a unit disk. The method relies on analytically continuing the initial data and equations of motion into the region exterior to the disk, where the evolution problem becomes well-posed. The equations are then numerically solved in the extended domain. The presence of singularities in the conformal map outside of the disk introduces specific structures along the fluid interface. Our method can explicitly track the location of isolated pole and branch point singularities, allowing us to draw connections between the development of interfacial patterns and the motion of singularities as they approach the unit disk. In particular, we are able to relate physical features such as finger shape, side-branch formation, and competition between fingers to the nature and location of the singularities. The usefulness of this method in studying the formation of topological singularities (self-intersections of the interface) is also pointed out.

DISC - APOLLO 11

NASA Image and Video Library

1969-07-14

S69-39148 (July 1969) --- Close-up view of the one and one-half inch silicon disk which will be left on the moon by the Apollo 11 astronauts. The disk bears messages of goodwill from heads of state of many nations. The process used to make this wafer is the same as that used to manufacture integrated circuits for electronic equipment. It involves making tiny photographic images and depositing metal on the images. The Kennedy half-dollar illustrates the relative size of the memorial disk.

Extraplanar H II Regions in Spiral Galaxies. I. Low-metallicity Gas Accreting through the Disk-halo Interface of NGC 4013

NASA Astrophysics Data System (ADS)

Howk, J. Christopher; Rueff, Katherine M.; Lehner, Nicolas; Wotta, Christopher B.; Croxall, Kevin; Savage, Blair D.

2018-04-01

The interstellar thick disks of galaxies serve as the interface between the thin star-forming disk, where feedback-driven outflows originate, and the distant halo, the repository for accreted gas. We present optical emission line spectroscopy of a luminous, thick disk H II region located at z = 860 pc above the plane of the spiral galaxy NGC 4013 taken with the Multi-Object Double Spectrograph on the Large Binocular Telescope. This nebula, with an Hα luminosity ∼4–7 times that of the Orion nebula, surrounds a luminous cluster of young, hot stars that ionize the surrounding interstellar gas of the thick disk, providing a measure of the properties of that gas. We demonstrate that strong emission line methods can provide accurate measures of relative abundances between pairs of H II regions. From our emission line spectroscopy, we show that the metal content of the thick disk H II region is a factor of ≈2 lower than gas in H II regions at the midplane of this galaxy (with the relative abundance of O in the thick disk lower by ‑0.32 ± 0.09 dex). This implies incomplete mixing of material in the thick disk on small scales (hundreds of parsecs) and that there is accretion of low-metallicity gas through the thick disks of spirals. The inclusion of low-metallicity gas this close to the plane of NGC 4013 is reminiscent of the recently proposed “fountain-driven” accretion models.

Magnetic bearings for a high-performance optical disk buffer, volume 1

NASA Technical Reports Server (NTRS)

Hockney, Richard; Adler, Karen; Anastas, George, Jr.; Downer, James; Flynn, Frederick; Goldie, James; Gondhalekar, Vijay; Hawkey, Timothy; Johnson, Bruce

1990-01-01

The innovation investigated in this project was the application of magnetic bearing technology to the translator head of an optical-disk data storage device. Both the capability for space-based applications and improved performance are expected to result. The phase 1 effort produced: (1) detailed specifications for both the translator-head and rotary-spindel bearings; (2) candidate hardware configurations for both bearings with detail definition for the translator head; (3) required characteristics for the magnetic bearing control loops; (4) position sensor selection; and (5) definition of the required electronic functions. The principal objective of Phase 2 was the design, fabrication, assembly, and test of the magnetic bearing system for the translator head. The scope of work included: (1) mechanical design of each of the required components; (2) electrical design of the required circuitry; (3) fabrication of the component parts and bread-board electronics; (4) generation of a test plan; and (5) integration of the prototype unit and performance testing. The project has confirmed the applicability of magnetic bearing technology to suspension of the translator head of the optical disk device, and demonstrated the achievement of all performance objectives. The magnetic bearing control loops perform well, achieving 100 Hz nominal bandwidth with phase margins between 37 and 63 degrees. The worst-case position resolution is 0.02 micron in the displacement loops and 1 micron rad in the rotation loops, The system is very robust to shock disturbances, recovering smoothly even when collisions occur between the translator and frame. The unique start-up/shut-down circuit has proven very effective.

An Analytical Calculation of Frictional and Bending Moments at the Head-Neck Interface of Hip Joint Implants during Different Physiological Activities.

PubMed

Farhoudi, Hamidreza; Oskouei, Reza H; Pasha Zanoosi, Ali A; Jones, Claire F; Taylor, Mark

2016-12-05

This study predicts the frictional moments at the head-cup interface and frictional torques and bending moments acting on the head-neck interface of a modular total hip replacement across a range of activities of daily living. The predicted moment and torque profiles are based on the kinematics of four patients and the implant characteristics of a metal-on-metal implant. Depending on the body weight and type of activity, the moments and torques had significant variations in both magnitude and direction over the activity cycles. For the nine investigated activities, the maximum magnitude of the frictional moment ranged from 2.6 to 7.1 Nm. The maximum magnitude of the torque acting on the head-neck interface ranged from 2.3 to 5.7 Nm. The bending moment acting on the head-neck interface varied from 7 to 21.6 Nm. One-leg-standing had the widest range of frictional torque on the head-neck interface (11 Nm) while normal walking had the smallest range (6.1 Nm). The widest range, together with the maximum magnitude of torque, bending moment, and frictional moment, occurred during one-leg-standing of the lightest patient. Most of the simulated activities resulted in frictional torques that were near the previously reported oxide layer depassivation threshold torque. The predicted bending moments were also found at a level believed to contribute to the oxide layer depassivation. The calculated magnitudes and directions of the moments, applied directly to the head-neck taper junction, provide realistic mechanical loading data for in vitro and computational studies on the mechanical behaviour and multi-axial fretting at the head-neck interface.

An Analytical Calculation of Frictional and Bending Moments at the Head-Neck Interface of Hip Joint Implants during Different Physiological Activities

PubMed Central

Farhoudi, Hamidreza; Oskouei, Reza H.; Pasha Zanoosi, Ali A.; Jones, Claire F.; Taylor, Mark

2016-01-01

This study predicts the frictional moments at the head-cup interface and frictional torques and bending moments acting on the head-neck interface of a modular total hip replacement across a range of activities of daily living. The predicted moment and torque profiles are based on the kinematics of four patients and the implant characteristics of a metal-on-metal implant. Depending on the body weight and type of activity, the moments and torques had significant variations in both magnitude and direction over the activity cycles. For the nine investigated activities, the maximum magnitude of the frictional moment ranged from 2.6 to 7.1 Nm. The maximum magnitude of the torque acting on the head-neck interface ranged from 2.3 to 5.7 Nm. The bending moment acting on the head-neck interface varied from 7 to 21.6 Nm. One-leg-standing had the widest range of frictional torque on the head-neck interface (11 Nm) while normal walking had the smallest range (6.1 Nm). The widest range, together with the maximum magnitude of torque, bending moment, and frictional moment, occurred during one-leg-standing of the lightest patient. Most of the simulated activities resulted in frictional torques that were near the previously reported oxide layer depassivation threshold torque. The predicted bending moments were also found at a level believed to contribute to the oxide layer depassivation. The calculated magnitudes and directions of the moments, applied directly to the head-neck taper junction, provide realistic mechanical loading data for in vitro and computational studies on the mechanical behaviour and multi-axial fretting at the head-neck interface. PMID:28774104

The Galley Parallel File System

NASA Technical Reports Server (NTRS)

Nieuwejaar, Nils; Kotz, David

1996-01-01

As the I/O needs of parallel scientific applications increase, file systems for multiprocessors are being designed to provide applications with parallel access to multiple disks. Many parallel file systems present applications with a conventional Unix-like interface that allows the application to access multiple disks transparently. The interface conceals the parallelism within the file system, which increases the ease of programmability, but makes it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. Furthermore, most current parallel file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic parallel workloads. We discuss Galley's file structure and application interface, as well as an application that has been implemented using that interface.

Micromagnetic structure in Co-alloy thin films and its correlation with microstructure

NASA Astrophysics Data System (ADS)

Tang, Kai

The development of magnetic hard disk recording has resulted in an increase of recording density in an accelerated pace. How to maintain the increasingly smaller bits with low noise presents a tremendous challenge to the recording media, which requires detailed study of micromagnetic structure of the media to understand the noise mechanism, and elucidation of the correlation between the micromagnetic structure and microstructure to systematically develop media materials and tailor their microstructure. Lorentz transmission electron microscopy (LTEM) is a high-resolution magnetic imaging technique. However, it requires uniformly thin specimens, which cannot be produced by conventional TEM specimen preparation methods. Consequently, its application to real computer magnetic hard disks has been limited. In this dissertation, a combined dimpling and chemical etching method is introduced to prepare specimens directly from the unmodified hard disks with the typical C/Co alloy/Cr/NiP/Al (substrate) structure. The specimens typically have 2000 μmsp2 or larger electron transparent areas of Co alloy/Cr films with uniform thickness, which are suitable for LTEM observation. This method is applicable to disks with both smooth and mechanically textured substrates. In this work, LTEM has been employed to study recorded patterns in real hard disks. Magnetic recording was performed on a standard spin stand. Bits of densities from 15 to 100 kfci were examined with head skew angles of 0sp° and 20sp°, respectively. We also compared tracks recorded on dc-erased disks with those on as-deposited disks. We observed magnetic ripples within the tracks and the inter-track regions, magnetic vortices of 0.1-0.2 mum in diameter at the bit-transitions, and curved magnetic domain walls in the track-edge regions resulting from the "dog-bone" shaped head field profile. Our results also indicate that the micromagnetic structure at the track edges is influenced by head skew and magnetization direction in the inter-track regions. The LTEM results are combined with MFM observations to provide further understanding. The study has concentrated on isotropic media on smooth substrates since low head-to-medium spacing required by high recording density demonstrates the need for this type of media. The recorded tracks are remanent magnetic states after a strong (head) magnetic field was applied. We also examined an ac-erased state, in which the effect of external field is removed. Magnetic vortices are identified, in which small crystal grains form magnetic clusters and these clusters then form closed-fluxed vortices. The size of these vortices is estimated to be around 1.0-1.5 mum, about 10 times larger than that found in the bit-transition regions. The smaller vortex sizes in the bit-transition regions may result from constraints from adjacent bits as well as the difference in magnetic processes generating these states. (Abstract shortened by UMI.)

Reaction kinetics and product distributions in photoelectrochemical cells

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

Koval, C.A.

1992-01-01

Hot electron reaction studies at p-InP/CH[sub 3]CN interface revealed essential/desirable features for redox systems used to investigate hot carriers in photoelectrocehmical cells. Reduction of dibromoethylbenzene (DBEB) in presence of metallocene couples is being studied using rotating rink disk electrodes of n-and p-InP disks and Pt rings. At highly doped p-InP electrodes, reduction of DBEB can be very efficient (>30%). A minielectrochemical cell was used to investigate electron transfer at nonilluminated n-WSe[sub 2]/dimethylferrocene[sup +/0] interfaces.

Jefferson Lab Mass Storage and File Replication Services

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

Ian Bird; Ying Chen; Bryan Hess

Jefferson Lab has implemented a scalable, distributed, high performance mass storage system - JASMine. The system is entirely implemented in Java, provides access to robotic tape storage and includes disk cache and stage manager components. The disk manager subsystem may be used independently to manage stand-alone disk pools. The system includes a scheduler to provide policy-based access to the storage systems. Security is provided by pluggable authentication modules and is implemented at the network socket level. The tape and disk cache systems have well defined interfaces in order to provide integration with grid-based services. The system is in production andmore » being used to archive 1 TB per day from the experiments, and currently moves over 2 TB per day total. This paper will describe the architecture of JASMine; discuss the rationale for building the system, and present a transparent 3rd party file replication service to move data to collaborating institutes using JASMine, XM L, and servlet technology interfacing to grid-based file transfer mechanisms.« less

Design and implementation of reliability evaluation of SAS hard disk based on RAID card

NASA Astrophysics Data System (ADS)

Ren, Shaohua; Han, Sen

2015-10-01

Because of the huge advantage of RAID technology in storage, it has been widely used. However, the question associated with this technology is that the hard disk based on the RAID card can not be queried by Operating System. Therefore how to read the self-information and log data of hard disk has been a problem, while this data is necessary for reliability test of hard disk. In traditional way, this information can be read just suitable for SATA hard disk, but not for SAS hard disk. In this paper, we provide a method by using LSI RAID card's Application Program Interface, communicating with RAID card and analyzing the feedback data to solve the problem. Then we will get the necessary information to assess the SAS hard disk.

A well-posed numerical method to track isolated conformal map singularities in Hele-Shaw flow

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

Baker, G.; Siegel, M.; Tanveer, S.

1995-09-01

We present a new numerical method for calculating an evolving 2D Hele-Shaw interface when surface tension effects are neglected. In the case where the flow is directed from the less viscous fluid into the more viscous fluid, the motion of the interface is ill-posed; small deviations in the initial condition will produce significant changes in the ensuing motion. The situation is disastrous for numerical computation, as small roundoff errors can quickly lead to large inaccuracies in the computed solution. Our method of computation is most easily formulated using a conformal map from the fluid domain into a unit disk. Themore » method relies on analytically continuing the initial data and equations of motion into the region exterior to the disk, where the evolution problem becomes well-posed. The equations are then numerically solved in the extended domain. The presence of singularities in the conformal map outside of the disk introduces specific structures along the fluid interface. Our method can explicitly track the location of isolated pole and branch point singularities, allowing us to draw connections between the development of interfacial patterns and the motion of singularities as they approach the unit disk. In particular, we are able to relate physical features such as finger shape, side-branch formation, and competition between fingers to the nature and location of the singularities. The usefulness of this method in studying the formation of topological singularities (self-intersections of the interface) is also pointed out. 47 refs., 10 figs., 1 tab.« less

Photonic content-addressable memory system that uses a parallel-readout optical disk

NASA Astrophysics Data System (ADS)

Krishnamoorthy, Ashok V.; Marchand, Philippe J.; Yayla, Gökçe; Esener, Sadik C.

1995-11-01

We describe a high-performance associative-memory system that can be implemented by means of an optical disk modified for parallel readout and a custom-designed silicon integrated circuit with parallel optical input. The system can achieve associative recall on 128 \\times 128 bit images and also on variable-size subimages. The system's behavior and performance are evaluated on the basis of experimental results on a motionless-head parallel-readout optical-disk system, logic simulations of the very-large-scale integrated chip, and a software emulation of the overall system.

Attacking the information access problem with expert systems

NASA Technical Reports Server (NTRS)

Ragusa, James M.; Orwig, Gary W.

1991-01-01

The results of applications research directed at finding an improved method of storing and accessing information are presented. Twelve microcomputer-based expert systems shells and five laser-optical formats have been studied, and the general and specific methods of interfacing these technologies are being tested in prototype systems. Shell features and interfacing capabilities are discussed, and results from the study of five laser-optical formats are recounted including the video laser, compact, and WORM disks, and laser cards and film. Interfacing, including laser disk device driver interfacing, is discussed and it is pointed out that in order to control the laser device from within the expert systems application, the expert systems shell must be able to access the device driver software. Potential integrated applications are investigated and an initial list is provided including consumer services, travel, law enforcement, human resources, marketing, and education and training.

Reaction kinetics and product distributions in photoelectrochemical cells. Technical progress report, March 15, 1992--March 14, 1993

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

Koval, C.A.

1992-12-01

Hot electron reaction studies at p-InP/CH{sub 3}CN interface revealed essential/desirable features for redox systems used to investigate hot carriers in photoelectrocehmical cells. Reduction of dibromoethylbenzene (DBEB) in presence of metallocene couples is being studied using rotating rink disk electrodes of n-and p-InP disks and Pt rings. At highly doped p-InP electrodes, reduction of DBEB can be very efficient (>30%). A minielectrochemical cell was used to investigate electron transfer at nonilluminated n-WSe{sub 2}/dimethylferrocene{sup +/0} interfaces.

Microstructure Evolution and Failure Analysis of an Aluminum-Copper Cathode Conductive Head Produced by Explosive Welding

NASA Astrophysics Data System (ADS)

Wei, Yanni; Luo, Yongguang; Qu, Hongtao; Zou, Juntao; Liang, Shuhua

2017-12-01

In this paper, microstructure evolution and failure analysis of the aluminum-copper interface of cathode conductive heads during their use were studied. The interface morphologies, compositions, conductivity and mechanical properties were investigated and analyzed. Obvious corrosion was found on the surface of the contact interface, which was more prevalent on an Al matrix. The crack increased sharply in the local metallurgical bonding areas on the interface, with the compound volume having no significant change. The phase transformation occurred on the interface during use, which was investigated using the elemental composition and x-ray diffraction pattern. The microhardness near the interface increased accordingly. An obvious electrical conductivity decrease appeared on the Al/Cu interface of the cathode conductive head after use over a specific time interval. Therefore, the deterioration of the microstructures and corrosion are the primary factors that affect the electrical conductivity and effective bonding, which will lead to eventual failure.

Human machine interface to manually drive rhombic like vehicles such as transport casks in ITER

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

Lopes, Pedro; Vale, Alberto; Ventura, Rodrigo

2015-07-01

The Cask and Plug Remote Handling System (CPRHS) and the respective Cask Transfer System (CTS) are designed to transport activated components between the reactor and the hot cell buildings of ITER during maintenance operations. In nominal operation, the CPRHS/CTS shall operate autonomously under human supervision. However, in some unexpected situations, the automatic mode must be overridden and the vehicle must be remotely guided by a human operator due to the harsh conditions of the environment. The CPRHS/CTS is a rhombic-like vehicle with two independent steerable and drivable wheels along its longitudinal axis, giving it omni-directional capabilities. During manual guidance, themore » human operator has to deal with four degrees of freedom, namely the orientations and speeds of two wheels. This work proposes a Human Machine Interface (HMI) to manage the degrees of freedom and to remotely guide the CPRHS/CTS in ITER taking the most advantages of rhombic like capabilities. Previous work was done to drive each wheel independently, i.e., control the orientation and speed of each wheel independently. The results have shown that the proposed solution is inefficient. The attention of the human operator becomes focused in a single wheel. In addition, the proposed solution cannot assure that the commands accomplish the physical constrains of the vehicle, resulting in slippage or even in clashes. This work proposes a solution that consists in the control of the vehicle looking at the position of its center of mass and its heading in the world frame. The solution is implemented using a rotational disk to control the vehicle heading and a common analogue joystick to control the vector speed of the center of the mass of the vehicle. The number of degrees of freedom reduces to three, i.e., two angles (vehicle heading and the orientation of the vector speed) and a scalar (the magnitude of the speed vector). This is possible using a kinematic model based on the vehicle Instantaneous Center of Rotation (ICR): a geometric approach where, at each time instant, the vehicle describes a circumference (either with a finite or infinite radius). The inverse of the kinematic model transforms the three input parameters of the center of mass into the four parameters for the wheels, preserving the omni-directional capabilities. The solution is implemented and tested using a HMI with a control disk and an analog joystick with two axis. The control disk was specially designed for this solution and implemented using a programmable micro-controller. In the first set of experiments, the HMI communicates with a computer running a simulator of the CPRHS/CTS, with the vehicle kinematics and dynamics, moving in a map of the ITER buildings. In the second set of experiments, the HMI communicates with a scaled prototype of the CPRHS running in a mock-up scenario to obtain more realistic results. Several type of tests were performed to evaluate the usability of the HMI. Different human operators without knowledge neither experience with this interface were invited to test the HMI. The operators had to drive the vehicle from an initial place to a final destination under the following conditions: with a pre-computed path to help guidance, without any path, with the information of the closest obstacles and without any help. The performance was evaluated using the time duration of the operation, the energy required to perform the described path, the risk of collision and, in case of a pre-computed path, the comparison between paths. In addition, each operator tested the HMI several times to evaluate the performance along consecutive trials. (authors)« less

A three-dimensional model for lubricant depletion under sliding condition on bit patterned media of hard disk drives

NASA Astrophysics Data System (ADS)

Wu, Lin

2018-05-01

In this paper, we model the depletion dynamics of the molecularly thin layer of lubricants on a bit patterned media disk of hard disk drives under a sliding air bearing head. The dominant physics and consequently, the lubricant depletion dynamics on a patterned disk are shown to be significantly different from the well-studied cases of a smooth disk. Our results indicate that the surface tension effect, which is negligible on a flat disk, apparently suppresses depletion by enforcing a bottleneck effect around the disk pattern peak regions to thwart the migration of lubricants. When the disjoining pressure is relatively small, it assists the depletion. But, when the disjoining pressure becomes dominant, the disjoining pressure resists depletion. Disk pattern orientation plays a critical role in the depletion process. The effect of disk pattern orientation on depletion originates from its complex interaction with other intermingled factors of external air shearing stress distribution and lubricant particle trajectory. Patterning a disk surface with nanostructures of high density, large height/pitch ratio, and particular orientation is demonstrated to be one efficient way to alleviate the formation of lubricant depletion tracks.

The saltwater-freshwater interface in the Tertiary limestone aquifer, southeast Atlantic outer-continental shelf of the U.S.A.

USGS Publications Warehouse

Johnston, R.H.

1983-01-01

Hydrologic testing in an offshore oil well abandoned by Tenneco, Inc., determined the position of the saltwater-freshwater interface in Tertiary limestones underlying the Florida-Georgia continental shelf of the U.S.A. Previous drilling (JOIDES and U.S.G.S. AMCOR projects) established the existence of freshwater far offshore in this area. At the Tenneco well 55 mi. (???88 km) east of Fernandina Beach, Florida, drill-stem tests made in the interval 1050-1070 ft. (320-326 m) below sea level in the Ocala Limestone recovered a sample with a chloride concentration of 7000 mg l-1. Formation water probably is slightly fresher. Pressure-head measurements indicated equivalent freshwater heads of 24-29 ft. (7.3-8.8 m) above sea level. At the coast (Fernandina Beach), a relatively thin transition zone separating freshwater and saltwater occurs at a depth of 2100 ft. (640 m) below sea level. Fifty-five miles (???88 km) offshore, at the Tenneco well, the base of freshwater is ???1100 ft. (???335 m) below sea level. The difference in approximate depth to the freshwater-saltwater transition at these two locations suggests an interface with a very slight landward slope. Assuming the Hubbert interface equation applies here (because the interface and therefore freshwater flow lines are nearly horizontal) the equilibrium depth to the interface should be 40 times the freshwater head above sea level. Using present-day freshwater heads along the coast in the Hubbert equation results in depths to the interface of less than the observed 2100 ft. (640 m). Substituting predevelopment heads in the equation yields depths greater than 2100 ft. (640 m). Thus the interface appears to be in a transient position between the position that would be compatible with present-day heads and the position that would be compatible with predevelopment heads. This implies that some movement of the interface from the predevelopment position has occurred during the past hundred years. The implied movement is incompatible with the hypothesis that the freshwater occurring far offshore in this area is trapped water remaining since the Pleistocene Epoch. ?? 1982.

Performance Evaluation and Software Design for EVA Robotic Assistant Stereo Vision Heads

NASA Technical Reports Server (NTRS)

DiPaolo, Daniel

2003-01-01

The purpose of this project was to aid the EVA Robotic Assistant project by evaluating and designing the necessary interfaces for two stereo vision heads - the TracLabs Biclops pan-tilt-verge head, and the Helpmate Zebra pan-tilt-verge head. The first half of the project consisted of designing the necessary software interface so that the other modules of the EVA Robotic Assistant had proper access to all of the functionalities offered by each of the stereovision heads. This half took most of the project time, due to a lack of ready-made CORBA drivers for either of the heads. Once this was overcome, the evaluation stage of the project began. The second half of the project was to take these interfaces and to evaluate each of the stereo vision heads in terms of usefulness to the project. In the key project areas such as stability and reliability, the Zebra pan-tilt-verge head came out on top. However, the Biclops did have many more advantages over the Zebra, such as: lower power consumption, faster communications, and a simpler, cleaner API. Overall, the Biclops pan-tilt-verge head outperformed the Zebra pan-tilt-verge head.

The interaction of plume heads with compositional discontinuities in the Earth's mantle

NASA Technical Reports Server (NTRS)

Manga, Michael; Stone, Howard A.; O'Connell, Richard J.

1993-01-01

The effects of compositional discontinuities of density and viscosity in the Earth's mantle on the ascent of mantle plume heads is studied using a boundary integral numerical technique. Three specific problems are considered: (1) a plume head rising away from a deformable interface, (2) a plume head passing through an interface, and (3) a plume head approaching the surface of the Earth. For the case of a plume attached to a free-surface, the calculated time-dependent plume shapesare compared with experimental results. Two principle modes of plume head deformation are observed: plume head elingation or the formation of a cavity inside the plume head. The inferred structure of mantle plumes, namely, a large plume head with a long tail, is characteristic of plumes attached to their source region, and also of buoyant material moving away from an interface and of buoyant material moving through an interface from a high- to low-viscosity region. As a rising plume head approaches the upper mantle, most of the lower mantle will quickly drain from the gap between the plume head and the upper mantle if the plume head enters the upper mantle. If the plume head moves from a high- to low-viscosity region, the plume head becomes significantly elongated and, for the viscosity contrasts thought to exist in the Earth, could extend from the 670 km discontinuity to the surface. Plume heads that are extended owing to a viscosity decrease in the upper mantle have a cylindrical geometry. The dynamic surface topography induced by plume heads is bell-shaped when the top of the plume head is at depths greater than about 0.1 plume head radii. As the plume head approaches the surface and spreads, the dynamic topography becomes plateau-shaped. The largest stresses are produced in the early stages of plume spreading when the plume head is still nearly spherical, and the surface expression of these stresses is likely to be dominated by radial extension. As the plume spreads, compressional stresses on the surface are produced beyond the edges of the plume; consequently, extensional features will be produced above the plume head and may be surrounded by a ring of compressional features.

Excitations of interface pinned domain walls in constrained geometries

NASA Astrophysics Data System (ADS)

Martins, S. M. S. B.; Oliveira, L. L.; Rebouças, G. O. G.; Dantas, Ana L.; Carriço, A. S.

2018-05-01

We report a theoretical investigation of the equilibrium pattern and the spectra of head-to-head and Neel domain walls of flat Fe and Py stripes, exchange coupled with a vicinal antiferromagnetic substrate. We show that the domain wall excitation spectrum is tunable by the strength of the interface field. Furthermore, strong interface coupling favors localized wall excitations.

On-Line Data Reconstruction in Redundant Disk Arrays.

DTIC Science & Technology

1994-05-01

each sale, - file servers that support a large number of clients with differing work schedules , and * automated teller networks in banking systems...24KB Head scheduling : FIFO User data layout: Sequential in address space of array Disk spindles: Synchronized Table 2.2: Default array parameters for...package and a set of scheduling and queueing routines. 2.3.3. Default workload This dissertation reports on many performance evaluations. In order to

Laser illuminator and optical system for disk patterning

DOEpatents

Hackel, Lloyd A.; Dane, C. Brent; Dixit, Shamasundar N.; Everett, Mathew; Honig, John

2000-01-01

Magnetic recording media are textured over areas designated for contact in order to minimize friction with data transducing heads. In fabricating a hard disk, an aluminum nickel-phosphorous substrate is polished to a specular finish. A mechanical means is then used to roughen an annular area intended to be the head contact band. An optical and mechanical system allows thousands of spots to be generated with each laser pulse, allowing the textured pattern to be rapidly generated with a low repetition rate laser and an uncomplicated mechanical system. The system uses a low power laser, a beam expander, a specially designed phase plate, a prism to deflect the beam, a lens to transmit the diffraction pattern to the far field, a mechanical means to rotate the pattern and a trigger system to fire the laser when sections of the pattern are precisely aligned. The system generates an annular segment of the desired pattern with which the total pattern is generated by rotating the optical system about its optic axis, sensing the rotational position and firing the laser as the annular segment rotates into the next appropriate position. This marking system can be integrated into a disk sputtering system for manufacturing magnetic disks, allowing for a very streamlined manufacturing process.

Surfactant Facilitated Spreading of Aqueous Drops on Hydrophobic Surfaces

NASA Technical Reports Server (NTRS)

Kumar, Nitin; Couzis, Alex; Maldareili, Charles; Singh, Bhim (Technical Monitor)

2001-01-01

Microgravity technologies often require aqueous phases to spread over nonwetting hydrophobic solid surfaces. Surfactants facilitate the wetting of water on hydrophobic surfaces by adsorbing on the water/air and hydrophobic solid/water interfaces and lowering the surface tensions of these interfaces. The tension reductions decrease the contact angle, which increases the equilibrium wetted area. Hydrocarbon surfactants; (i.e., amphiphiles with a hydrophobic moiety consisting of an extended chain of (aliphatic) methylene -CH2- groups attached to a large polar group to give aqueous solubility) are capable of reducing the contact angles on surfaces which are not very hydrophobic, but do not reduce significantly the contact angles of the very hydrophobic surfaces such as parafilm, polyethylene or self assembled monolayers. Trisiloxane surfactants (amphiphiles with a hydrophobe consisting of methyl groups linked to a trisiloxane backbone in the form of a disk ((CH3)3-Si-O-Si-O-Si(CH3)3) and an extended ethoxylate (-(OCH2CH2)a-) polar group in the form of a chain with four or eight units) can significantly reduce the contact angle of water on a very hydrophobic surface and cause rapid and complete (or nearly complete) spreading (termed superspreading). The overall goal of the research described in this proposal is to establish and verify a theory for how trisiloxanes cause superspreading, and then use this knowledge as a guide to developing more general hydrocarbon based surfactant systems which superspread. We propose that the trisiloxane surfactants superspread because their structure allows them to strongly lower the high hydrophobic solid/aqueous tension when they adsorb to the solid surface. When the siloxane adsorbs, the hydrophobic disk parts of the molecule adsorb onto the surface removing the surface water. Since the cross-sectional area of the disk is larger than that of the extended ethoxylate chain, the disks can form a space-filling mat on the surface which removes a significant amount of the surface water. In this presentation, we report the results of measurements of the molecular packing and rates of kinetic exchange of the trisiloxane surfactants at the air/water interface in order to confirm our picture of trisiloxane packing, and provide additional insight into the superspreading process. We used the pendant bubble technique as a Langmuir trough to measure the trisiloxane equation of state which relates the tension to the surface concentration. From these measurements we obtain accurate values for the maximum packing density. We find that trisiloxanes with 4 and 8 ethoxylate groups have the same maximum packing concentration, indicating that the maximum packing is controlled by the cross section of the head group. For trisiloxanes with larger than eight ethoxylates, the maximum packing increases with ethoxylate number, indicating that the disposition of the ethoxylate chain (i.e., its effective size) is controlling. This supports our picture of superspreading: The superspreading ability of trisiloxanes decreases considerably for trisiloxanes with larger than eight ethoxylates; the packing measurements indicate that for the higher ethoxylate number trisiloxanes, the compact nonpolar head groups are pushed apart by the ethoxylate chain. They leave spaces of surface water on adsorption and do not lower the solid tension as much as their lower chain analogues. Finally the report measurements of the dynamic tension reduction accompanying the adsorption of trisiloxanes onto an initially clean interface using the pendant bubble technique, and we obtain from these relaxations, the equation of state and a mass transfer model, the rate constants for kinetic exchange. We find that the rate constants for desorption of trisiloxanes are generally much slower than for analogous aliphatic polyethoxylate surfactants with identical ethoxylate chain lengths. When an aqueous drop of a superspreader solution is placed on a hydrophobic surface and begins to spread, the lower desorption rates allows the tension at the drop center to remain reduced relative to the tension of the expanding periphery, thus strengthening Marangoni forces which can assist the spreading. Marangoni forces can be especially significant in the case of superspreaders because their maximum equilibrium reduction in tension is several dynes/cm lower than for aliphatic surfactants.

Radiative Transfer Modeling in Proto-planetary Disks

NASA Astrophysics Data System (ADS)

Kasper, David; Jang-Condell, Hannah; Kloster, Dylan

2016-01-01

Young Stellar Objects (YSOs) are rich astronomical research environments. Planets form in circumstellar disks of gas and dust around YSOs. With ever increasing capabilities of the observational instruments designed to look at these proto-planetary disks, most notably GPI, SPHERE, and ALMA, more accurate interfaces must be made to connect modeling of the disks with observation. PaRTY (Parallel Radiative Transfer in YSOs) is a code developed previously to model the observable density and temperature structure of such a disk by self-consistently calculating the structure of the disk based on radiative transfer physics. We present upgrades we are implementing to the PaRTY code to improve its accuracy and flexibility. These upgrades include: creating a two-sided disk model, implementing a spherical coordinate system, and implementing wavelength-dependent opacities. These upgrades will address problems in the PaRTY code of infinite optical thickness, calculation under/over-resolution, and wavelength-independent photon penetration depths, respectively. The upgraded code will be used to better model disk perturbations resulting from planet formation.

SODR Memory Control Buffer Control ASIC

NASA Technical Reports Server (NTRS)

Hodson, Robert F.

1994-01-01

The Spacecraft Optical Disk Recorder (SODR) is a state of the art mass storage system for future NASA missions requiring high transmission rates and a large capacity storage system. This report covers the design and development of an SODR memory buffer control applications specific integrated circuit (ASIC). The memory buffer control ASIC has two primary functions: (1) buffering data to prevent loss of data during disk access times, (2) converting data formats from a high performance parallel interface format to a small computer systems interface format. Ten 144 p in, 50 MHz CMOS ASIC's were designed, fabricated and tested to implement the memory buffer control function.

Rate dependent direct inverse hysteresis compensation of piezoelectric micro-actuator used in dual-stage hard disk drive head positioning system.

PubMed

Rahman, Md Arifur; Al Mamun, Abdullah; Yao, Kui

2015-08-01

The head positioning servo system in hard disk drive is implemented nowadays using a dual-stage actuator—the primary stage consisting of a voice coil motor actuator providing long range motion and the secondary stage controlling the position of the read/write head with fine resolution. Piezoelectric micro-actuator made of lead zirconate titanate (PZT) has been a popular choice for the secondary stage. However, PZT micro-actuator exhibits hysteresis—an inherent nonlinear characteristic of piezoelectric material. The advantage expected from using the secondary micro-actuator is somewhat lost by the hysteresis of the micro-actuator that contributes to tracking error. Hysteresis nonlinearity adversely affects the performance and, if not compensated, may cause inaccuracy and oscillation in the response. Compensation of hysteresis is therefore an important aspect for designing head-positioning servo system. This paper presents a new rate dependent model of hysteresis along with rigorous analysis and identification of the model. Parameters of the model are found using particle swarm optimization. Direct inverse of the proposed rate-dependent generalized Prandtl-Ishlinskii model is used as the hysteresis compensator. Effectiveness of the overall solution is underscored through experimental results.

Observational constraints on black hole accretion disks

NASA Technical Reports Server (NTRS)

Liang, Edison P.

1994-01-01

We review the empirical constraints on accretion disk models of stellar-mass black holes based on recent multiwavelength observational results. In addition to time-averaged emission spectra, the time evolutions of the intensity and spectrum provide critical information about the structure, stability, and dynamics of the disk. Using the basic thermal Keplerian disk paradigm, we consider in particular generalizations of the standard optically thin disk models needed to accommodate the extremely rich variety of dynamical phenomena exhibited by black hole candidates ranging from flares of electron-positron annihilations and quasiperiodic oscillations in the X-ray intensity to X-ray novae activity. These in turn provide probes of the disk structure and global geometry. The goal is to construct a single unified framework to interpret a large variety of black hole phenomena. This paper will concentrate on the interface between basic theory and observational data modeling.

Multi-modal cockpit interface for improved airport surface operations

NASA Technical Reports Server (NTRS)

Arthur, Jarvis J. (Inventor); Bailey, Randall E. (Inventor); Prinzel, III, Lawrence J. (Inventor); Kramer, Lynda J. (Inventor); Williams, Steven P. (Inventor)

2010-01-01

A system for multi-modal cockpit interface during surface operation of an aircraft comprises a head tracking device, a processing element, and a full-color head worn display. The processing element is configured to receive head position information from the head tracking device, to receive current location information of the aircraft, and to render a virtual airport scene corresponding to the head position information and the current aircraft location. The full-color head worn display is configured to receive the virtual airport scene from the processing element and to display the virtual airport scene. The current location information may be received from one of a global positioning system or an inertial navigation system.

Network issues for large mass storage requirements

NASA Technical Reports Server (NTRS)

Perdue, James

1992-01-01

File Servers and Supercomputing environments need high performance networks to balance the I/O requirements seen in today's demanding computing scenarios. UltraNet is one solution which permits both high aggregate transfer rates and high task-to-task transfer rates as demonstrated in actual tests. UltraNet provides this capability as both a Server-to-Server and Server-to-Client access network giving the supercomputing center the following advantages highest performance Transport Level connections (to 40 MBytes/sec effective rates); matches the throughput of the emerging high performance disk technologies, such as RAID, parallel head transfer devices and software striping; supports standard network and file system applications using SOCKET's based application program interface such as FTP, rcp, rdump, etc.; supports access to the Network File System (NFS) and LARGE aggregate bandwidth for large NFS usage; provides access to a distributed, hierarchical data server capability using DISCOS UniTree product; supports file server solutions available from multiple vendors, including Cray, Convex, Alliant, FPS, IBM, and others.

High-temperature geothermal cableheads

NASA Astrophysics Data System (ADS)

Coquat, J. A.; Eifert, R. W.

1981-11-01

Two high temperature, corrosion resistant logging cable heads which use metal seals and a stable fluid to achieve proper electrical terminations and cable sonde interfacings are described. A tensile bar provides a calibrated yield point, and a cone assembly anchors the cable armor to the head. Electrical problems of the sort generally ascribable to the cable sonde interface were absent during demonstration hostile environment loggings in which these cable heads were used.

Dentin-Composite Bond Strength Measurement Using the Brazilian Disk Test

PubMed Central

Carrera, Carola A.; Chen, Yung-Chung; Li, Yuping; Rudney, Joel; Aparicio, Conrado; Fok, Alex

2016-01-01

Objectives This study presents a variant of the Brazilian disk test (BDT) for assessing the bond strength between composite resins and dentin. Methods Dentin-composite disks (φ 5 mm × 2 mm) were prepared using either Z100 or Z250 (3M ESPE) in combination with one of three adhesives, Adper Easy Bond (EB), Adper Scotchbond Multi-Purpose (MP) and Adper Single Bond (SB), and tested under diametral compression. Acoustic emission (AE) and digital image correlation (DIC) were used to monitor debonding of the composite from the dentin ring. A finite element (FE) model was created to calculate the bond strengths using the failure loads. Fracture modes were examined by scanning electron microscopy (SEM). Results Most specimens fractured along the dentin-resin composite interface. DIC and AE confirmed interfacial debonding immediately before fracture of the dentin ring. Results showed that the mean bond strength with EB (14.9±1.9 MPa) was significantly higher than with MP (13.2±2.4 MPa) or SB (12.9±3.0 MPa) (p<0.05); no significant difference was found between MP and SB (p>0.05). Z100 (14.5±2.3 MPa) showed higher bond strength than Z250 (12.7±2.5 MPa) (p<0.05). Majority of specimens (91.3%) showed an adhesive failure mode. EB failed mostly at the dentin-adhesive interface, whereas MP at the composite-adhesive interface; specimens with SB failed at the composite-adhesive interface and cohesively in the adhesive. Conclusions The BDT variant showed to be a suitable alternative for measuring the bond strength between dentin and composite, with zero premature failure, reduced variability in the measurements, and consistent failure at the dentin-composite interface. PMID:27395367

The development of the cucullaris muscle and the branchial musculature in the Longnose Gar, (Lepisosteus osseus, Lepisosteiformes, Actinopterygii) and its implications for the evolution and development of the head/trunk interface in vertebrates.

PubMed

Naumann, Benjamin; Warth, Peter; Olsson, Lennart; Konstantinidis, Peter

2017-11-01

The vertebrate head/trunk interface is the region of the body where the different developmental programs of the head and trunk come in contact. Many anatomical structures that develop in this transition zone differ from similar structures in the head or the trunk. This is best exemplified by the cucullaris/trapezius muscle, spanning the head/trunk interface by connecting the head to the pectoral girdle. The source of this muscle has been claimed to be either the unsegmented head mesoderm or the somites of the trunk. However most recent data on the development of the cucullaris muscle are derived from tetrapods and information from actinopterygian taxa is scarce. We used classical histology in combination with fluorescent whole-mount antibody staining and micro-computed tomography to investigate the developmental pattern of the cucullaris and the branchial muscles in a basal actinopterygian, the Longnose gar (Lepisosteus osseus). Our results show (1) that the cucullaris has been misidentified in earlier studies on its development in Lepisosteus. (2) Cucullaris development is delayed compared to other head and trunk muscles. (3) This developmental pattern of the cucullaris is similar to that reported from some tetrapod taxa. (4) That the retractor dorsalis muscle of L. osseus shows a delayed developmental pattern similar to the cucullaris. Our data are in agreement with an explanatory scenario for the cucullaris development in tetrapods, suggesting that these mechanisms are conserved throughout the Osteichthyes. Furthermore the developmental pattern of the retractor dorsalis, also spanning the head/trunk interface, seems to be controlled by similar mechanisms. © 2017 Wiley Periodicals, Inc.

Improved design of a cone-shaped rotating disk for shear force loading in a cell culture plate

NASA Astrophysics Data System (ADS)

Keawprachum, Boonrit; Limjeerajarus, Nuttapol; Nakalekha Limjeerajarus, Chalida; Srisungsitthisunti, Pornsak

2018-01-01

In our previous study, a cone-shaped rotating disk had been designed and proposed for generating shear force on the cell in a cell culture plate. This study aims to improve the design of the rotating disk that could provide a better uniformity of shear stress distribution. The top of the cone was designed to be trimmed off to obtain a flat head area. The effect of tilt angle (θ) was numerically studied using computational fluid dynamics (CFD) technique in ANSYS-Fluent software. The results revealed that for 500 rpm, the new designed rotating disk with a height of cone-shaped top to the plate bottom h = 1 mm and θ = 25° provided the best uniformity of 0.820 which was better than that of the previously designed.

Software Graphical User Interface For Analysis Of Images

NASA Technical Reports Server (NTRS)

Leonard, Desiree M.; Nolf, Scott R.; Avis, Elizabeth L.; Stacy, Kathryn

1992-01-01

CAMTOOL software provides graphical interface between Sun Microsystems workstation and Eikonix Model 1412 digitizing camera system. Camera scans and digitizes images, halftones, reflectives, transmissives, rigid or flexible flat material, or three-dimensional objects. Users digitize images and select from three destinations: work-station display screen, magnetic-tape drive, or hard disk. Written in C.

Application of M-JPEG compression hardware to dynamic stimulus production.

PubMed

Mulligan, J B

1997-01-01

Inexpensive circuit boards have appeared on the market which transform a normal micro-computer's disk drive into a video disk capable of playing extended video sequences in real time. This technology enables the performance of experiments which were previously impossible, or at least prohibitively expensive. The new technology achieves this capability using special-purpose hardware to compress and decompress individual video frames, enabling a video stream to be transferred over relatively low-bandwidth disk interfaces. This paper will describe the use of such devices for visual psychophysics and present the technical issues that must be considered when evaluating individual products.

Corrosion at the head-neck interface of current designs of modular femoral components: essential questions and answers relating to corrosion in modular head-neck junctions.

PubMed

Osman, K; Panagiotidou, A P; Khan, M; Blunn, G; Haddad, F S

2016-05-01

There is increasing global awareness of adverse reactions to metal debris and elevated serum metal ion concentrations following the use of second generation metal-on-metal total hip arthroplasties. The high incidence of these complications can be largely attributed to corrosion at the head-neck interface. Severe corrosion of the taper is identified most commonly in association with larger diameter femoral heads. However, there is emerging evidence of varying levels of corrosion observed in retrieved components with smaller diameter femoral heads. This same mechanism of galvanic and mechanically-assisted crevice corrosion has been observed in metal-on-polyethylene and ceramic components, suggesting an inherent biomechanical problem with current designs of the head-neck interface. We provide a review of the fundamental questions and answers clinicians and researchers must understand regarding corrosion of the taper, and its relevance to current orthopaedic practice. Cite this article: Bone Joint J 2016;98-B:579-84. ©2016 The British Editorial Society of Bone & Joint Surgery.

50-mJ, 1-kHz Yb:YAG thin-disk regenerative amplifier with 969-nm pulsed pumping

NASA Astrophysics Data System (ADS)

Chyla, Michal; Miura, Taisuke; Smrž, Martin; Severova, Patricie; Novak, Ondrej; Endo, Akira; Mocek, Tomas

2014-02-01

We are developing a 100-mJ Yb:YAG thin-disk regenerative amplifier operating at 1-kHz repetition rate pumped at zero-phonon-line (968.825-nm1) and delivering 1-2 ps pulses for EUV plasma sources applicable in science and industry. Recently we achieved the output energy of nearly 50-mJ from a single laser-head cavity with good beam quality (M2<1.2) as well as stable beam-pointing (<4μrad). Applying pulsed pumping with the pulse duration shorter than the upper state lifetime of Yb:YAG helps to reduce the ASE and thermal loading of the thin-disk.

The Influence of Contamination and Cleaning on the Strength of Modular Head Taper Fixation in Total Hip Arthroplasty.

PubMed

Krull, Annika; Morlock, Michael M; Bishop, Nicholas E

2017-10-01

Intraoperative interface contamination of modular head-stem taper junctions of hip implants can lead to poor fixation strength, causing fretting and crevice corrosion or even stem taper fracture. Careful cleaning before assembly should help to reduce these problems. The purpose of this study was to determine the effect of cleaning (with and without drying) contaminated taper interfaces on the taper fixation strength. Metal or ceramic heads were impacted onto titanium alloy stem tapers with cleaned or contaminated (fat or saline solution) interfaces. The same procedure was performed after cleaning and drying the contaminated interfaces. Pull-off force was used to determine the influence of contamination and cleaning on the taper strength. Pull-off forces after contamination with fat were significantly lower than those for uncontaminated interfaces for both head materials. Pull-off forces after application of saline solution were not significantly different from those for uncontaminated tapers. However, a large variation in taper strength was observed, pull-off forces for cleaned and dried tapers were similar to those for uncontaminated tapers for both head materials. Intraoperative contamination of taper interfaces may be difficult to detect but has a major influence on taper fixation strength. Cleaning of the stem taper with saline solution and drying with gauze directly before assembly allows the taper strength of the pristine components to be achieved. Not drying the taper results in a large variation in pull-off forces, emphasizing that drying is essential for sufficient and reproducible fixation strength. Copyright © 2017 Elsevier Inc. All rights reserved.

The advantage of an alternative substrate over Al/NiP disks

NASA Astrophysics Data System (ADS)

Jiaa, Chi L.; Eltoukhy, Atef

1994-02-01

Compact-size disk drives with high storage densities are in high demand due to the popularity of portable computers and workstations. The contact-start-stop (CSS) endurance performance must improve in order to accomodate the higher number of on/off cycles. In this paper, we looked at 65 mm thin-film canasite substrate disks and evaluated their mechanical performance. We compared them with conventional aluminum NiP-plated disks in surface topography, take-off time with changes of skew angles and radius, CSS, drag test and glide height performance, and clamping effect. In addition, a new post-sputter process aimed at the improvement of take-off and glide as well as CSS performances was investigated and demonstrated for the canasite disks. From the test results, it is indicated that canasite achieved a lower take-off velocity, higher clamping resistance, and better glide height and CSS endurance performance. This study concludes that a new generation disk drive equipped with canasite substrate disks will consume less power from the motor due to faster take-off and lighter weight, achieve higher recording density since the head flies lower, can better withstand damage from sliding friction during the CSS operations, and will be less prone to disk distortion from clamping due to its superior mechanical properties.

TADPOLE GALAXIES IN THE HUBBLE ULTRA DEEP FIELD

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

Elmegreen, Bruce G.; Elmegreen, Debra Meloy, E-mail: bge@watson.ibm.co, E-mail: elmegreen@vassar.ed

2010-10-20

Tadpole galaxies have a head-tail shape with a large clump of star formation at the head and a diffuse tail or streak of stars off to one side. We measured the head and tail masses, ages, surface brightnesses, and sizes for 66 tadpoles in the Hubble Ultra Deep Field (UDF) and looked at the distribution of neighbor densities and tadpole orientations with respect to neighbors. The heads have masses of 10{sup 7}-10{sup 8} M{sub sun} and photometric ages of {approx}0.1 Gyr for z {approx} 2. The tails have slightly larger masses than the heads and comparable or slightly older ages.more » The most obvious interpretation of tadpoles as young merger remnants is difficult to verify. They have no enhanced proximity to other resolved galaxies as a class, and the heads, typically <0.2 kpc in diameter, usually have no obvious double-core structure. Another possibility is ram pressure interaction between a gas-rich galaxy and a diffuse cosmological flow. Ram pressure can trigger star formation on one side of a galaxy disk, giving the tadpole shape when viewed edge-on. Ram pressure can also strip away gas from a galaxy and put it into a tail, which then forms new stars and gravitationally drags along old stars with it. Such an effect might have already been observed in the Virgo Cluster. Another possibility is that tadpoles are edge-on disks with large, off-center clumps. Analogous lop-sided star formation in UDF clump clusters is shown.« less

An almost head-on collision as the origin of two off-centre rings in the Andromeda galaxy.

PubMed

Block, D L; Bournaud, F; Combes, F; Groess, R; Barmby, P; Ashby, M L N; Fazio, G G; Pahre, M A; Willner, S P

2006-10-19

The unusual morphology of the Andromeda galaxy (Messier 31, the closest spiral galaxy to the Milky Way) has long been an enigma. Although regarded for decades as showing little evidence of a violent history, M31 has a well-known outer ring of star formation at a radius of ten kiloparsecs whose centre is offset from the galaxy nucleus. In addition, the outer galaxy disk is warped, as seen at both optical and radio wavelengths. The halo contains numerous loops and ripples. Here we report the presence of a second, inner dust ring with projected dimensions of 1.5 x 1 kiloparsecs and offset by about half a kiloparsec from the centre of the galaxy (based upon an analysis of previously-obtained data). The two rings appear to be density waves propagating in the disk. Numerical simulations indicate that both rings result from a companion galaxy plunging through the centre of the disk of M31. The most likely interloper is M32. Head-on collisions between galaxies are rare, but it appears nonetheless that one took place 210 million years ago in our Local Group of galaxies.

AFTOMS Technology Issues and Alternatives Report

DTIC Science & Technology

1989-12-01

color , resolu- power requirements, physi- tion; memory , processor speed; cal and weather rugged- IAN interfaces, etc,) f,: these ness. display...Telephone and Telegraph 3 CD-I Compact Disk - Interactive CD-ROM Compact Disk-Read Only Memory CGM Computer Graphics Metafile CNWDI Critical Nuclear...Database Management System RFP Request For Proposal 3 RFS Remote File System ROM Read Only Memory 3 S SA-ALC San Antonio Air Logistics Center 3 SAC

Robust human machine interface based on head movements applied to assistive robotics.

PubMed

Perez, Elisa; López, Natalia; Orosco, Eugenio; Soria, Carlos; Mut, Vicente; Freire-Bastos, Teodiano

2013-01-01

This paper presents an interface that uses two different sensing techniques and combines both results through a fusion process to obtain the minimum-variance estimator of the orientation of the user's head. Sensing techniques of the interface are based on an inertial sensor and artificial vision. The orientation of the user's head is used to steer the navigation of a robotic wheelchair. Also, a control algorithm for assistive technology system is presented. The system is evaluated by four individuals with severe motors disability and a quantitative index was developed, in order to objectively evaluate the performance. The results obtained are promising since most users could perform the proposed tasks with the robotic wheelchair.

Robust Human Machine Interface Based on Head Movements Applied to Assistive Robotics

PubMed Central

Perez, Elisa; López, Natalia; Orosco, Eugenio; Soria, Carlos; Mut, Vicente; Freire-Bastos, Teodiano

2013-01-01

This paper presents an interface that uses two different sensing techniques and combines both results through a fusion process to obtain the minimum-variance estimator of the orientation of the user's head. Sensing techniques of the interface are based on an inertial sensor and artificial vision. The orientation of the user's head is used to steer the navigation of a robotic wheelchair. Also, a control algorithm for assistive technology system is presented. The system is evaluated by four individuals with severe motors disability and a quantitative index was developed, in order to objectively evaluate the performance. The results obtained are promising since most users could perform the proposed tasks with the robotic wheelchair. PMID:24453877

Biologic Effects of Electric and Magnetic Fields Associated with Proposed Project Seafarer

DTIC Science & Technology

1977-01-01

controlled laboratory conditions. The differences were equivalent to those produced by 0 temperature changes of about 1 C, which would affect only...with the control grouo .! 13 Finally, Krueger and his colleagues have investigated the effects of electromagnetic fields on fecundity in chickens. One...flight from a release point 18 miles (29 km) west of the home colony, control birds (with non -magnetic nylon disks glued to their 0 heads) headed

Dual-probe near-field fiber head with gap servo control for data storage applications.

PubMed

Fang, Jen-Yu; Tien, Chung-Hao; Shieh, Han-Ping D

2007-10-29

We present a novel fiber-based near-field optical head consisting of a straw-shaped writing probe and a flat gap sensing probe. The straw-shaped probe with a C-aperture on the end face exhibits enhanced transmission by a factor of 3 orders of magnitude over a conventional fiber probe due to a hybrid effect that excites both propagation modes and surface plasmon waves. In the gap sensing probe, the spacing between the probe and the disk surface functions as an external cavity. The high sensitivity of the output power to the change in the gap width is used as a feedback control signal. We characterize and design the straw-shaped writing probe and the flat gap sensing probe. The dual-probe system is installed on a conventional biaxial actuator to demonstrate the capability of flying over a disk surface with nanometer position precision.

Development of a software interface for optical disk archival storage for a new life sciences flight experiments computer

NASA Technical Reports Server (NTRS)

Bartram, Peter N.

1989-01-01

The current Life Sciences Laboratory Equipment (LSLE) microcomputer for life sciences experiment data acquisition is now obsolete. Among the weaknesses of the current microcomputer are small memory size, relatively slow analog data sampling rates, and the lack of a bulk data storage device. While life science investigators normally prefer data to be transmitted to Earth as it is taken, this is not always possible. No down-link exists for experiments performed in the Shuttle middeck region. One important aspect of a replacement microcomputer is provision for in-flight storage of experimental data. The Write Once, Read Many (WORM) optical disk was studied because of its high storage density, data integrity, and the availability of a space-qualified unit. In keeping with the goals for a replacement microcomputer based upon commercially available components and standard interfaces, the system studied includes a Small Computer System Interface (SCSI) for interfacing the WORM drive. The system itself is designed around the STD bus, using readily available boards. Configurations examined were: (1) master processor board and slave processor board with the SCSI interface; (2) master processor with SCSI interface; (3) master processor with SCSI and Direct Memory Access (DMA); (4) master processor controlling a separate STD bus SCSI board; and (5) master processor controlling a separate STD bus SCSI board with DMA.

Archiving and Distributing Seismic Data at the Southern California Earthquake Data Center (SCEDC)

NASA Astrophysics Data System (ADS)

Appel, V. L.

2002-12-01

The Southern California Earthquake Data Center (SCEDC) archives and provides public access to earthquake parametric and waveform data gathered by the Southern California Seismic Network and since January 1, 2001, the TriNet seismic network, southern California's earthquake monitoring network. The parametric data in the archive includes earthquake locations, magnitudes, moment-tensor solutions and phase picks. The SCEDC waveform archive prior to TriNet consists primarily of short-period, 100-samples-per-second waveforms from the SCSN. The addition of the TriNet array added continuous recordings of 155 broadband stations (20 samples per second or less), and triggered seismograms from 200 accelerometers and 200 short-period instruments. Since the Data Center and TriNet use the same Oracle database system, new earthquake data are available to the seismological community in near real-time. Primary access to the database and waveforms is through the Seismogram Transfer Program (STP) interface. The interface enables users to search the database for earthquake information, phase picks, and continuous and triggered waveform data. Output is available in SAC, miniSEED, and other formats. Both the raw counts format (V0) and the gain-corrected format (V1) of COSMOS (Consortium of Organizations for Strong-Motion Observation Systems) are now supported by STP. EQQuest is an interface to prepackaged waveform data sets for select earthquakes in Southern California stored at the SCEDC. Waveform data for large-magnitude events have been prepared and new data sets will be available for download in near real-time following major events. The parametric data from 1981 to present has been loaded into the Oracle 9.2.0.1 database system and the waveforms for that time period have been converted to mSEED format and are accessible through the STP interface. The DISC optical-disk system (the "jukebox") that currently serves as the mass-storage for the SCEDC is in the process of being replaced with a series of inexpensive high-capacity (1.6 Tbyte) magnetic-disk RAIDs. These systems are built with PC-technology components, using 16 120-Gbyte IDE disks, hot-swappable disk trays, two RAID controllers, dual redundant power supplies and a Linux operating system. The system is configured over a private gigabit network that connects to the two Data Center servers and spans between the Seismological Lab and the USGS. To ensure data integrity, each RAID disk system constantly checks itself against its twin and verifies file integrity using 128-bit MD5 file checksums that are stored separate from the system. The final level of data protection is a Sony AIT-3 tape backup of the files. The primary advantage of the magnetic-disk approach is faster data access because magnetic disk drives have almost no latency. This means that the SCEDC can provide better "on-demand" interactive delivery of the seismograms in the archive.

Distributed Sensor Systems and Electromechanical Analog Facility

DTIC Science & Technology

1980-01-01

interfaces (parallel I/O, modems , etc.) real time operating systems (perhaps a short survey of what is available in the industry today), data...consists of a LSI-11 microprocessor, 56K bytes of memory, and serial and parallel I/O boards. 2.1.7 Disk controller The standard disk controller...with MTS via the modems connected to the LSI-lls. This pseudodevice cannot be reassigned. OSWIT I/O AND INTERRUPT STRUCTURE 137 OSWIT

DMA shared byte counters in a parallel computer

DOEpatents

Chen, Dong; Gara, Alan G.; Heidelberger, Philip; Vranas, Pavlos

2010-04-06

A parallel computer system is constructed as a network of interconnected compute nodes. Each of the compute nodes includes at least one processor, a memory and a DMA engine. The DMA engine includes a processor interface for interfacing with the at least one processor, DMA logic, a memory interface for interfacing with the memory, a DMA network interface for interfacing with the network, injection and reception byte counters, injection and reception FIFO metadata, and status registers and control registers. The injection FIFOs maintain memory locations of the injection FIFO metadata memory locations including its current head and tail, and the reception FIFOs maintain the reception FIFO metadata memory locations including its current head and tail. The injection byte counters and reception byte counters may be shared between messages.

Computer Lab Tools for Science: An Analysis of Commercially Available Science Interfacing Software for Microcomputers. A Quarterly Report.

ERIC Educational Resources Information Center

Weaver, Dave

Science interfacing packages (also known as microcomputer-based laboratories or probeware) generally consist of a set of programs on disks, a user's manual, and hardware which includes one or more sensory devices. Together with a microcomputer they combine to make a powerful data acquisition and analysis tool. Packages are available for accurately…

LOCAL TADPOLE GALAXIES: DYNAMICS AND METALLICITY

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

Sanchez Almeida, J.; Munoz-Tunon, C.; Mendez-Abreu, J.

2013-04-10

Tadpole galaxies, with a bright peripheral clump on a faint tail, are morphological types unusual in the nearby universe but very common early on. Low mass local tadpoles were identified and studied photometrically in a previous work, which we complete here analyzing their chemical and dynamical properties. We measure H{alpha} velocity curves of seven local tadpoles, representing 50% of the initial sample. Five of them show evidence for rotation ({approx}70%), and a sixth target hints at it. Often the center of rotation is spatially offset with respect to the tadpole head (three out of five cases). The size and velocitymore » dispersion of the heads are typical of giant H II regions, and three of them yield dynamical masses in fair agreement with their stellar masses as inferred from photometry. In four cases the velocity dispersion at the head is reduced with respect to its immediate surroundings. The oxygen metallicity estimated from [N II] {lambda}6583/H{alpha} often shows significant spatial variations across the galaxies ({approx}0.5 dex), being smallest at the head and larger elsewhere. The resulting chemical abundance gradients are opposite to the ones observed in local spirals, but agrees with disk galaxies at high redshift. We interpret the metallicity variation as a sign of external gas accretion (cold-flows) onto the head of the tadpole. The galaxies are low-metallicity outliers of the mass-metallicity relationship. In particular, two of the tadpole heads are extremely metal poor, with a metallicity smaller than a tenth of the solar value. These two targets are also very young (ages smaller than 5 Myr). All these results combined are consistent with the local tadpole galaxies being disks in early stages of assembling, with their star formation sustained by accretion of external metal-poor gas.« less

Finite-frequency sensitivity kernels for head waves

NASA Astrophysics Data System (ADS)

Zhang, Zhigang; Shen, Yang; Zhao, Li

2007-11-01

Head waves are extremely important in determining the structure of the predominantly layered Earth. While several recent studies have shown the diffractive nature and the 3-D Fréchet kernels of finite-frequency turning waves, analogues of head waves in a continuous velocity structure, the finite-frequency effects and sensitivity kernels of head waves are yet to be carefully examined. We present the results of a numerical study focusing on the finite-frequency effects of head waves. Our model has a low-velocity layer over a high-velocity half-space and a cylindrical-shaped velocity perturbation placed beneath the interface at different locations. A 3-D finite-difference method is used to calculate synthetic waveforms. Traveltime and amplitude anomalies are measured by the cross-correlation of synthetic seismograms from models with and without the velocity perturbation and are compared to the 3-D sensitivity kernels constructed from full waveform simulations. The results show that the head wave arrival-time and amplitude are influenced by the velocity structure surrounding the ray path in a pattern that is consistent with the Fresnel zones. Unlike the `banana-doughnut' traveltime sensitivity kernels of turning waves, the traveltime sensitivity of the head wave along the ray path below the interface is weak, but non-zero. Below the ray path, the traveltime sensitivity reaches the maximum (absolute value) at a depth that depends on the wavelength and propagation distance. The sensitivity kernels vary with the vertical velocity gradient in the lower layer, but the variation is relatively small at short propagation distances when the vertical velocity gradient is within the range of the commonly accepted values. Finally, the depression or shoaling of the interface results in increased or decreased sensitivities, respectively, beneath the interface topography.

Galactic scale gas flows in colliding galaxies: 3-dimensional, N-body/hydrodynamics experiments

NASA Technical Reports Server (NTRS)

Lamb, Susan A.; Gerber, Richard A.; Balsara, Dinshaw S.

1994-01-01

We present some results from three dimensional computer simulations of collisions between models of equal mass galaxies, one of which is a rotating, disk galaxy containing both gas and stars and the other is an elliptical containing stars only. We use fully self consistent models in which the halo mass is 2.5 times that of the disk. In the experiments we have varied the impact parameter between zero (head on) and 0.9R (where R is the radius of the disk), for impacts perpendicular to the disk plane. The calculations were performed on a Cray 2 computer using a combined N-body/smooth particle hydrodynamics (SPH) program. The results show the development of complicated flows and shock structures in the direction perpendicular to the plane of the disk and the propagation outwards of a density wave in both the stars and the gas. The collisional nature of the gas results in a sharper ring than obtained for the star particles, and the development of high volume densities and shocks.

TRANSITION DISK CHEMISTRY AND FUTURE PROSPECTS WITH ALMA

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

Cleeves, L. Ilsedore; Bergin, Edwin A.; Bethell, Thomas J.

2011-12-10

We explore the chemical structure of a disk that contains a large central gap of R {approx} 45 AU, as is commonly seen in transitional disk systems. In our chemical model of a disk with a cleared inner void, the midplane becomes revealed to the central star so that it is directly irradiated. The midplane material at the truncation radius is permissive to reprocessed optical heating radiation, but opaque to the photodissociating ultraviolet, creating an environment abundant in gas-phase molecules. Thus the disk midplane, which would otherwise for a full disk be dominated by near complete heavy element freeze-out, shouldmore » become observable in molecular emission. If this prediction is correct this has exciting prospects for observations with the Atacama Large Millimeter/Submillimeter Array, as the inner transition region should thus be readily detected and resolved, especially using high-J rotational transitions excited in the high density midplane gas. Therefore, such observations will potentially provide us with a direct probe of the physics and chemistry at this actively evolving interface.« less

The CDF Run II disk inventory manager

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

Paul Hubbard and Stephan Lammel

2001-11-02

The Collider Detector at Fermilab (CDF) experiment records and analyses proton-antiproton interactions at a center-of-mass energy of 2 TeV. Run II of the Fermilab Tevatron started in April of this year. The duration of the run is expected to be over two years. One of the main data handling strategies of CDF for Run II is to hide all tape access from the user and to facilitate sharing of data and thus disk space. A disk inventory manager was designed and developed over the past years to keep track of the data on disk, to coordinate user access to themore » data, and to stage data back from tape to disk as needed. The CDF Run II disk inventory manager consists of a server process, a user and administrator command line interfaces, and a library with the routines of the client API. Data are managed in filesets which are groups of one or more files. The system keeps track of user access to the filesets and attempts to keep frequently accessed data on disk. Data that are not on disk are automatically staged back from tape as needed. For CDF the main staging method is based on the mt-tools package as tapes are written according to the ANSI standard.« less

Initial utilization of the CVIRB video production facility

NASA Technical Reports Server (NTRS)

Parrish, Russell V.; Busquets, Anthony M.; Hogge, Thomas W.

1987-01-01

Video disk technology is one of the central themes of a technology demonstrator workstation being assembled as a man/machine interface for the Space Station Data Management Test Bed at Johnson Space Center. Langley Research Center personnel involved in the conception and implementation of this workstation have assembled a video production facility to allow production of video disk material for this propose. This paper documents the initial familiarization efforts in the field of video production for those personnel and that facility. Although the entire video disk production cycle was not operational for this initial effort, the production of a simulated disk on video tape did acquaint the personnel with the processes involved and with the operation of the hardware. Invaluable experience in storyboarding, script writing, audio and video recording, and audio and video editing was gained in the production process.

Borehole geophysical, fluid, and hydraulic properties within and surrounding the freshwater/saline-water transition zone, San Antonio segment of the Edwards aquifer, south-central Texas, 2010-11

USGS Publications Warehouse

Thomas, Jonathan V.; Stanton, Gregory P.; Lambert, Rebecca B.

2012-01-01

Although analyses of daily mean equivalent freshwater heads for the East Uvalde transect indicated that the gradient across the freshwater/saline-water interface varied between into and out of the freshwater zone, the data indicate that there was a slightly longer period during which the gradient was out of the freshwater zone. Analyses of all daily mean equivalent freshwater heads for the Tri-County transect indicated that the lateral-head gradients across the freshwater/saline-water interface were typically mixed (not indicative of flow into or out of freshwater zone). Assessment of the daily mean equivalent freshwater heads indicated that, although the lateral-head gradient at the Kyle transect varied between into and out of the freshwater zone, the lateral-head gradient was typically from the transition zone into the freshwater zone.

An improved maximum permissible exposure meter for safety assessments of laser radiation

NASA Astrophysics Data System (ADS)

Corder, D. A.; Evans, D. R.; Tyrer, J. R.

1997-12-01

Current interest in laser radiation safety requires demonstration that a laser system has been designed to prevent exposure to levels of laser radiation exceeding the Maximum Permissible Exposure. In some simple systems it is possible to prove this by calculation, but in most cases it is preferable to confirm calculated results with a measurement. This measurement may be made with commercially available equipment, but there are limitations with this approach. A custom designed instrument is presented in which the full range of measurement issues have been addressed. Important features of the instrument are the design and optimisation of detector heads for the measurement task, and consideration of user interface requirements. Three designs for detector head are presented, these cover the majority of common laser types. Detector heads are designed to optimise the performance of relatively low cost detector elements for this measurement task. The three detector head designs are suitable for interfacing to photodiodes, low power thermopiles and pyroelectric detectors. Design of the user interface was an important aspect of the work. A user interface which is designed for the specific application minimises the risk of user error or misinterpretation of the measurement results. A palmtop computer was used to provide an advanced user interface. User requirements were considered in order that the final implement was well matched to the task of laser radiation hazard audits.

Enhancement of current-perpendicular-to-plane giant magnetoresistance in Heusler-alloy based pseudo spin valves by using a CuZn spacer layer

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

Furubayashi, T., E-mail: furubayashi.takao@nims.go.jp; Takahashi, Y. K.; Sasaki, T. T.

2015-10-28

Enhancement of magnetoresistance output was attained in current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices by using a bcc CuZn alloy for the spacer. Pseudo spin valves that consisted of the Co{sub 2}Fe(Ga{sub 0.5}Ge{sub 0.5}) Heusler alloy for ferromagnetic layers and CuZn alloy with the composition of Cu{sub 52.4}Zn{sub 47.6} for a spacer showed the large change of the resistance-area products, ΔRA, up to 8 mΩ·μm{sup 2} for a low annealing temperature of 350 °C. The ΔRA value is one of the highest reported so far for the CPP-GMR devices for the low annealing temperature, which is essential for processing read heads for hardmore » disk drives. We consider that the enhancement of ΔRA is produced from the spin-dependent resistance at the Co{sub 2}Fe(Ga{sub 0.5}Ge{sub 0.5})/CuZn interfaces.« less

Comparison of the retention of 5 core materials supported by a dental post.

PubMed

Gu, Steven; Isidro, Mario; Deutsch, Allan S; Musikant, Barry L

2006-01-01

This study evaluated the retention of dental post heads (No. 2 Flexi-Post) embedded in 5 core materials (1 automix resin composite, 2 hand-mixed resin composites, and 2 glass ionomers). Samples were prepared by embedding post heads in 4.5-mm-thick disks of core material. The resin composite materials provided significantly more retention than the glass-ionomer-based materials. The post head retention of the automix resin composite was comparable to that of the hand-mixed resin composites. Unlike the resin composite samples, all the glass-ionomer samples fractured during testing. This is an unacceptable condition for a clinically successful restoration.

Research Studies on Advanced Optical Module/Head Designs for Optical Data Storage

NASA Technical Reports Server (NTRS)

1992-01-01

Preprints are presented from the recent 1992 Optical Data Storage meeting in San Jose. The papers are divided into the following topical areas: Magneto-optical media (Modeling/design and fabrication/characterization/testing); Optical heads (holographic optical elements); and Optical heads (integrated optics). Some representative titles are as follow: Diffraction analysis and evaluation of several focus and track error detection schemes for magneto-optical disk systems; Proposal for massively parallel data storage system; Transfer function characteristics of super resolving systems; Modeling and measurement of a micro-optic beam deflector; Oxidation processes in magneto-optic and related materials; and A modal analysis of lamellar diffraction gratings in conical mountings.

Will New Metal Heads Restore Mechanical Integrity of Corroded Trunnions?

PubMed

Derasari, Aditya; Gold, Jonathan E; Ismaily, Sabir; Noble, Philip C; Incavo, Stephen J

2017-04-01

Metal wear and corrosion from modular junctions in total hip arthroplasty can lead to further unwanted surgery. Trunnion tribocorrosion is recognized as an important contributor to failure. This study was performed to determine if new metal heads restore mechanical integrity of the original modular junction after impaction on corroded trunnions, and assess which variables affect stability of the new interface created at revision total hip arthroplasty. Twenty-two trunnions, cobalt-chromium (CoCr) and titanium alloy (TiAIV), (CoCr, n = 12; TiAIV, n = 10) and new metal heads were used, 10 trunnions in pristine condition and 12 with corrosion damage. Test states were performed using an MTS Machine and included the following: 1, Assembly; 2, Disassembly; 3, Assembly; 4, Toggling; and 5, Disassembly. During loading, three-dimensional motion of the head-trunnion junction was measured using a custom jig. There were no statistical differences in the tested mechanical properties between corroded and pristine trunnions implanted with a new metal femoral head. Average micromotion of the head versus trunnion interface was greatest at the start of loading, stabilizing after approximately 50 loading cycles at an average of 30.6 ± 3.2 μm. Corrosion at the trunnion does not disrupt mechanical integrity of the junction when a CoCr head is replaced with a CoCr trunnion. However, increased interface motion of a new metal head on a corroded titanium trunnion requires additional study. The evaluation of ball head size on mechanical integrity of trunnions would also be a potential subject of future investigation, as increasing the ball head size at the time of revision is not uncommon in revisions today. Copyright © 2016 Elsevier Inc. All rights reserved.

The Dynamics of Truncated Black Hole Accretion Disks. I. Viscous Hydrodynamic Case

NASA Astrophysics Data System (ADS)

Hogg, J. Drew; Reynolds, Christopher S.

2017-07-01

Truncated accretion disks are commonly invoked to explain the spectro-temporal variability in accreting black holes in both small systems, I.e., state transitions in galactic black hole binaries (GBHBs), and large systems, I.e., low-luminosity active galactic nuclei (LLAGNs). In the canonical truncated disk model of moderately low accretion rate systems, gas in the inner region of the accretion disk occupies a hot, radiatively inefficient phase, which leads to a geometrically thick disk, while the gas in the outer region occupies a cooler, radiatively efficient phase that resides in the standard geometrically thin disk. Observationally, there is strong empirical evidence to support this phenomenological model, but a detailed understanding of the dynamics of truncated disks is lacking. We present a well-resolved viscous, hydrodynamic simulation that uses an ad hoc cooling prescription to drive a thermal instability and, hence, produce the first sustained truncated accretion disk. With this simulation, we perform a study of the dynamics, angular momentum transport, and energetics of a truncated disk. We find that the time variability introduced by the quasi-periodic transition of gas from efficient cooling to inefficient cooling impacts the evolution of the simulated disk. A consequence of the thermal instability is that an outflow is launched from the hot/cold gas interface, which drives large, sub-Keplerian convective cells into the disk atmosphere. The convective cells introduce a viscous θ - ϕ stress that is less than the generic r - ϕ viscous stress component, but greatly influences the evolution of the disk. In the truncated disk, we find that the bulk of the accreted gas is in the hot phase.

The Dynamics of Truncated Black Hole Accretion Disks. I. Viscous Hydrodynamic Case

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

Hogg, J. Drew; Reynolds, Christopher S.

Truncated accretion disks are commonly invoked to explain the spectro-temporal variability in accreting black holes in both small systems, i.e., state transitions in galactic black hole binaries (GBHBs), and large systems, i.e., low-luminosity active galactic nuclei (LLAGNs). In the canonical truncated disk model of moderately low accretion rate systems, gas in the inner region of the accretion disk occupies a hot, radiatively inefficient phase, which leads to a geometrically thick disk, while the gas in the outer region occupies a cooler, radiatively efficient phase that resides in the standard geometrically thin disk. Observationally, there is strong empirical evidence to supportmore » this phenomenological model, but a detailed understanding of the dynamics of truncated disks is lacking. We present a well-resolved viscous, hydrodynamic simulation that uses an ad hoc cooling prescription to drive a thermal instability and, hence, produce the first sustained truncated accretion disk. With this simulation, we perform a study of the dynamics, angular momentum transport, and energetics of a truncated disk. We find that the time variability introduced by the quasi-periodic transition of gas from efficient cooling to inefficient cooling impacts the evolution of the simulated disk. A consequence of the thermal instability is that an outflow is launched from the hot/cold gas interface, which drives large, sub-Keplerian convective cells into the disk atmosphere. The convective cells introduce a viscous θ − ϕ stress that is less than the generic r − ϕ viscous stress component, but greatly influences the evolution of the disk. In the truncated disk, we find that the bulk of the accreted gas is in the hot phase.« less

Teaching Hyporheic and Groundwater Flow Concepts Using an Interactive Computer Simulation

NASA Astrophysics Data System (ADS)

Stonedahl, S. H.; Stonedahl, F.

2016-12-01

We built an educational flow simulator with an interactive web-based interface that allows students to investigate the effects of arbitrary head functions on water flowing through various configurations of permeable/impermeable sediments. The domain consists of a 24 by 48 rectangular grid of sediments with no-flow bottom and side boundaries and a constant head surface water-groundwater (SWGW) interface boundary. The SWGW interface head function can be drawn freehand with the mouse or specified to be a step function, a sine curve, or a zig-zag function, where the amplitude and wavenumber parameters of the head functions are chosen by the user. The subsurface domain may be modified by drawing no-flow (impermeable) barriers in the sediment, changing any number of the 1152 grid cells into no flow cells. The program iteratively solves the Laplace equation to calculate head values at each grid cell within the sediment. Users can then start water particles along the SWGW interface and track their paths through the system to visualize the head-induced flow. Sediment cells can be color coded by head values or water speed. Exploring these systems with the simulator allows users to improve their understanding of the relationship between head and velocity as well as how the position of no-flow barriers impacts water flow in saturated sediments. These learning objectives are amenable to our target audience of undergraduate students, but younger (middle/high school) students may also be able to absorb key concepts by playing with the simulation. The structure of the simulation itself highlights the broader idea of simulation of natural processes through the discretization of continuous environments. The simulation was developed using the NetLogo platform and runs embedded in a webpage: http://susa.stonedahl.com/swgwsimulator. The simulation source code is available and can readily be modified by other educators (or students) to create additional features and options.

Effects of head field and AC field on magnetization reversal for microwave assisted magnetic recording

NASA Astrophysics Data System (ADS)

Kase, Aina; Akagi, Fumiko; Yoshida, Kazuetsu

2018-05-01

Microwave assisted magnetic recording (MAMR) is a promising recording method for achieving high recording densities in hard disk drives. In MAMR, the AC field from a spin-torque oscillator (STO) assists the head field with magnetization reversal in a medium. Therefore, the relationship between the head field and the AC field is very important. In this study, the effects of the head field and the AC field on magnetization reversal were analyzed using a micromagnetic simulator that takes the magnetic interactions between a single-pole type (SPT) write-head, an exchange coupled composite (ECC) medium, and the STO into account. As a result, the magnetization reversal was assisted not just by the y-component of the AC field (Hstoy) but also by the y-component of the head field (Hhy) in the medium. The Hhy over 100 kA/m with a frequency of about 15.5 GHz induced the magnetic resonance. The large Hhy was produced by the field from the STO to the SPT head.

Failure mechanisms and closed reduction of a constrained tripolar acetabular liner.

PubMed

Robertson, William J; Mattern, Christopher J; Hur, John; Su, Edwin P; Pellicci, Paul M

2009-02-01

Unlike traditional bipolar constrained liners, the Osteonics Omnifit constrained acetabular insert is a tripolar device, consisting of an inner bipolar bearing articulating within an outer, true liner. Every reported failure of the Omnifit tripolar implant has been by failure at the shell-bone interface (Type I failure), failure at the shell-liner interface (Type II failure), or failure of the locking mechanism resulting in dislocation of the bipolar-liner interface (Type III failure). In this report we present two cases of failure of the Omnifit tripolar at the bipolar-femoral head interface. To our knowledge, these are the first reported cases of failure at the bipolar-femoral head interface (Type IV failure). In addition, we described the first successful closed reduction of a Type IV failure.

Evaluation of head orientation and neck muscle EMG signals as three-dimensional command sources.

PubMed

Williams, Matthew R; Kirsch, Robert F

2015-03-05

High cervical spinal cord injuries result in significant functional impairments and affect both the injured individual as well as their family and care givers. To help restore function to these individuals, multiple user interfaces are available to enable command and control of external devices. However, little work has been performed to assess the 3D performance of these interfaces. We investigated the performance of eight human subjects in using three user interfaces (head orientation, EMG from muscles of the head and neck, and a three-axis joystick) to command the endpoint position of a multi-axis robotic arm within a 3D workspace to perform a novel out-to-center 3D Fitts' Law style task. Two of these interfaces (head orientation, EMG from muscles of the head and neck) could realistically be used by individuals with high tetraplegia, while the joystick was evaluated as a standard of high performance. Performance metrics were developed to assess the aspects of command source performance. Data were analyzed using a mixed model design ANOVA. Fixed effects were investigated between sources as well as for interactions between index of difficulty, command source, and the five performance measures used. A 5% threshold for statistical significance was used in the analysis. The performances of the three command interfaces were rather similar, though significant differences between command sources were observed. The apparent similarity is due in large part to the sequential command strategy (i.e., one dimension of movement at a time) typically adopted by the subjects. EMG-based commands were particularly pulsatile in nature. The use of sequential commands had a significant impact on each command source's performance for movements in two or three dimensions. While the sequential nature of the commands produced by the user did not fit with Fitts' Law, the other performance measures used were able to illustrate the properties of each command source. Though pulsatile, given the overall similarity between head orientation and the EMG interface, (which also could be readily included in a future implanted neuroprosthesis) the use of EMG as a command source for controlling an arm in 3D space is an attractive choice.

Structure and functions of simple membrane-water interfaces. [Abstract only

NASA Technical Reports Server (NTRS)

Pohorille, A.; Wilson, M. A.

1994-01-01

The structure and functions of the earliest ancestors of contemporary cells are focal points in studies of the origin of life. Probably the first cell-like structures were vesicles - closed, spheroidal structures with aqueous medium trapped inside. The membranous walls of vesicles were most likely bilayers composed of simple amphiphilic material available on early earth. The membrane studied was composed of glycerol 1-monooleate (GMO). Glycerol forms the polar head group and the oily tail contains 18 carbon atoms. All head groups have been found to be located in two narrow regions at the interfaces with water. The membrane interior, formed by the hydrophobic tails, is quite fluid with chain disorder increasing towards the center of the bilayer. These results are in agreement with x-ray and neutron scattering data from related bilayers. The width of the membrane is not constant, but fluctuates in time and space. Occasional thinning defects in the membrane, observed during the course of the simulations, may have a significant influence on rates of passive transport of small molecules across membranes. It has been found that water penetrates the head group region but not the oily interior of the membrane. Water molecules near the interface are oriented by dipoles of the head groups. The resulting electrostatic potential across the interface, determined in our simulations, has been found to be markedly larger than across the water-oil interface. This quantity has been implicated as the source of selectivity, with respect to the sign of the charge, as an ion approaches the interface and during transport of hydrophobic ions across membranes.

Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk Around PDS 70: Observations of the Disk

NASA Technical Reports Server (NTRS)

Hashimoto, J.; Dong, R.; Kudo, T.; Honda, M.; Zhu, Z.; McClure, M. K.; Muto, T.; Wisniewski, J.; Abe, L.; Brandner, W.;

The HD 163296 Circumstellar Disk in Scattered Light: Evidence of Time-Variable Self-Shadowing

NASA Technical Reports Server (NTRS)

Wisniewski, John P.; Clampin, Mark; Grady, Carol A.; Ardila, David R.; Ford, Holland C.; Golimowski, David A.; Illingworth, Garth D.; Krist, John E.

2008-01-01

We present the first multi-color view of the scattered light disk of the Herbig Ae star HD 163296, based on coronagraphic observations from the Hubble Space Telescope Advanced Camera for Surveys (ACS). Radial profile fits of the surface brightness along the disk's semi-major axis indicates that the disk is not continuously flared, and extends to approx.540 AU. The disk's color (V-I)=1.1 at a radial distance of 3.5" is redder than the observed stellar color (V-I)=0.15. This red disk color might be indicative of either an evolution in the grain size distribution (i.e. grain growth) and/or composition, both of which would be consistent with the observed non-flared geometry of the outer disk. We also identify a single ansa morphological structure in our F435W ACS data, which is absent from earlier epoch F606W and F814W ACS data, but corresponds to one of the two ansa observed in archival HST STIS coronagraphic data. Following transformation to similar band-passes, we find that the scattered light disk of HD 163296 is 1 mag arcsec(sup -2) fainter at 3.5" in the STIS data than in the ACS data. Moreover, variations are seen in (i) the visibility of the ansa(e) structures, in (ii) the relative surface brightness of the ansa(e) structures, and in (iii) the (known) intrinsic polarization of the system. These results indicate that the scattered light from the HD 163296 disk is variable. We speculate that the inner disk wall, which Sitko et al. suggests has a variable scale height as diagnosed by near-IR SED variability, induces variable self-shadowing of the outer disk. We further speculate that the observed surface brightness variability of the ansa(e) structures may indicate that the inner disk wall is azimuthally asymmetric. Subject headings: circumstellar matter - stars: individual (HD 163296) - planetary systems: formation - planetary systems: protoplanetary disks

Formation and stability of twisted ribbons in mixtures of rod-like fd-virus and non-adsorbing polymer

NASA Astrophysics Data System (ADS)

Dogic, Z.; Didonna, B.; Bryning, M.; Lubensky, T. C.; Yodh, A. G.; Janmey, P. A.

2003-03-01

We are investigating the behavior of mixtures of monodisperse fd-virus rods and non-adsorbing polymer. We observe the formation of isolated smectic disks. The single smectic disk is of a monolayer of aligned rods while its thickness equal to the length of a single rod. As disks coalesce they undergo shape transformations from flat structures to elongated twisted ribbons. A theoretical model is formulated wherein the chirality of the molecule favors the formation of the elongated ribbon structure while the line tension favors formation of untwisted disks. To check the validity of the theoretical model line tension and twist constants are experimentally measured. The line tension is deduced from thermal fluctuations of the interface. The twist constant is determined by unwinding the twisted ribbons using optical tweezers. This work is partially supported by NSF grants DMR-0203378, the PENN MRSEC, DMR-0079909, and NASA grant NAG8-2172.

Development and Preliminary Application of Multi-channel Agricultural Science and Technology Consulting Service U Disk

NASA Astrophysics Data System (ADS)

Yu, W. S.; Luo, C. S.; Wei, Q. F.; Zheng, Y. M.; Cao, C. Z.

2017-12-01

To deal with the “last kilometer” problem during the agricultural science and technology information service, the USB flash disk “Zixuntong”, which integrated five major consulting channels, i.e., telephone consultation, mutual video, message consultation, online customer service and QQ group was developed on the bases of capital experts and date resources. Since the products have the computer and telephone USB interface and are combined with localized information resources, users can obtain useful information on any terminal without the restriction of network. Meanwhile, the cartoon appearance make it friendly and attractive to people. The USB flash disk was used to provide agricultural expert consulting services and obtained a good preliminary application achievement. Finally, we concluded the creative application of USB flash disk in agricultural consulting services and prospected the future development direction of agricultural mobile consultation.

Architecture and method for a burst buffer using flash technology

DOEpatents

Tzelnic, Percy; Faibish, Sorin; Gupta, Uday K.; Bent, John; Grider, Gary Alan; Chen, Hsing-bung

2016-03-15

A parallel supercomputing cluster includes compute nodes interconnected in a mesh of data links for executing an MPI job, and solid-state storage nodes each linked to a respective group of the compute nodes for receiving checkpoint data from the respective compute nodes, and magnetic disk storage linked to each of the solid-state storage nodes for asynchronous migration of the checkpoint data from the solid-state storage nodes to the magnetic disk storage. Each solid-state storage node presents a file system interface to the MPI job, and multiple MPI processes of the MPI job write the checkpoint data to a shared file in the solid-state storage in a strided fashion, and the solid-state storage node asynchronously migrates the checkpoint data from the shared file in the solid-state storage to the magnetic disk storage and writes the checkpoint data to the magnetic disk storage in a sequential fashion.

Shrinking galaxy disks with fountain-driven accretion from the halo

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

Elmegreen, Bruce G.; Struck, Curtis; Hunter, Deidre A., E-mail: bge@watson.ibm.com, E-mail: curt@iastate.edu, E-mail: dah@lowell.edu

2014-12-01

Star formation in most galaxies requires cosmic gas accretion because the gas consumption time is short compared to the Hubble time. This accretion presumably comes from a combination of infalling satellite debris, cold flows, and condensation of hot halo gas at the cool disk interface, perhaps aided by a galactic fountain. In general, the accretion will have a different specific angular momentum than the part of the disk that receives it, even if the gas comes from the nearby halo. The gas disk then expands or shrinks over time. Here we show that condensation of halo gas at a ratemore » proportional to the star formation rate in the fountain model will preserve an initial shape, such as an exponential, with a shrinking scale length, leaving behind a stellar disk with a slightly steeper profile of younger stars near the center. This process is slow for most galaxies, producing imperceptible radial speeds, and it may be dominated by other torques, but it could be important for blue compact dwarfs, which tend to have large, irregular gas reservoirs and steep blue profiles in their inner stellar disks.« less

The Development of a Portable Hard Disk Encryption/Decryption System with a MEMS Coded Lock.

PubMed

Zhang, Weiping; Chen, Wenyuan; Tang, Jian; Xu, Peng; Li, Yibin; Li, Shengyong

2009-01-01

In this paper, a novel portable hard-disk encryption/decryption system with a MEMS coded lock is presented, which can authenticate the user and provide the key for the AES encryption/decryption module. The portable hard-disk encryption/decryption system is composed of the authentication module, the USB portable hard-disk interface card, the ATA protocol command decoder module, the data encryption/decryption module, the cipher key management module, the MEMS coded lock controlling circuit module, the MEMS coded lock and the hard disk. The ATA protocol circuit, the MEMS control circuit and AES encryption/decryption circuit are designed and realized by FPGA(Field Programmable Gate Array). The MEMS coded lock with two couplers and two groups of counter-meshing-gears (CMGs) are fabricated by a LIGA-like process and precision engineering method. The whole prototype was fabricated and tested. The test results show that the user's password could be correctly discriminated by the MEMS coded lock, and the AES encryption module could get the key from the MEMS coded lock. Moreover, the data in the hard-disk could be encrypted or decrypted, and the read-write speed of the dataflow could reach 17 MB/s in Ultra DMA mode.

Lubricant dynamics under sliding condition in disk drives

NASA Astrophysics Data System (ADS)

Wu, Lin

2006-07-01

In this paper, we develop a two-dimensional flow model for the lubricant flow dynamics under a sliding head in disk drives. Our two-dimensional model includes important physics such as viscous force, external air shearing stress, air bearing pressure, centrifugal force, disjoining pressure, and surface tension. Our analysis shows that the lubricant flow dynamics under the sliding condition is a fully two-dimensional phenomenon and the circumferential lubricant flow is strongly coupled to the radial flow. It is necessary to have a two-dimensional flow model that couples the circumferential and radial flows together and includes all important physics to achieve realistic predictions. Our results show that the external air shearing stress has a dominant effect on the lubricant flow dynamics. Both velocity slippage at wall and Poiseuille flow effects have to be considered in the evaluation of the air shearing stress under the head. The nonuniform air bearing pressure has a non-negligible effect on the lubricant film dynamics mostly through the Poiseuille flow effect on the air shearing stress but not from its direct pushing or sucking effect on the lubricant surface. Prediction of the formation of lubricant depletion tracks under a sliding head using the two-dimensional model agrees reasonably well with the existing experimental measurements.

Fabrication of universal serial bus flash disk type microfluidic chip electrophoresis and application for protein analysis under ultra low voltage

PubMed Central

Cong, Hailin; Xu, Xiaodan; Yu, Bing; Liu, Huwei

2016-01-01

A simple and effective universal serial bus (USB) flash disk type microfluidic chip electrophoresis (MCE) was developed by using poly(dimethylsiloxane) based soft lithography and dry film based printed circuit board etching techniques in this paper. The MCE had a microchannel diameter of 375 μm and an effective length of 25 mm. Equipped with a conventional online electrochemical detector, the device enabled effectively separation of bovine serum albumin, lysozyme, and cytochrome c in 80 s under the ultra low voltage from a computer USB interface. Compared with traditional capillary electrophoresis, the USB flash disk type MCE is not only portable and inexpensive but also fast with high separation efficiency. PMID:27042249

Dielectric Haloscopes: A New Way to Detect Axion Dark Matter.

PubMed

Caldwell, Allen; Dvali, Gia; Majorovits, Béla; Millar, Alexander; Raffelt, Georg; Redondo, Javier; Reimann, Olaf; Simon, Frank; Steffen, Frank

2017-03-03

We propose a new strategy to search for dark matter axions in the mass range of 40-400 μeV by introducing dielectric haloscopes, which consist of dielectric disks placed in a magnetic field. The changing dielectric media cause discontinuities in the axion-induced electric field, leading to the generation of propagating electromagnetic waves to satisfy the continuity requirements at the interfaces. Large-area disks with adjustable distances boost the microwave signal (10-100 GHz) to an observable level and allow one to scan over a broad axion mass range. A sensitivity to QCD axion models is conceivable with 80 disks of 1  m^{2} area contained in a 10 T field.

Fan-head shear rupture mechanism as a source of off-fault tensile cracking

NASA Astrophysics Data System (ADS)

Tarasov, Boris

2016-04-01

This presentation discusses the role of a recently identified fan-head shear rupture mechanism [1] in the creation of off-fault tensile cracks observed in earthquake laboratory experiments conducted on brittle photoelastic specimens [2,3]. According to the fan-mechanism the shear rupture propagation is associated with consecutive creation of small slabs in the fracture tip which, due to rotation caused by shear displacement of the fracture interfaces, form a fan-structure representing the fracture head. The fan-head combines such unique features as: extremely low shear resistance (below the frictional strength) and self-sustaining tensile stress intensification along one side of the interface. The variation of tensile stress within the fan-head zone is like this: it increases with distance from the fracture tip up to a maximum value and then decreases. For the initial formation of the fan-head high local stresses corresponding to the fracture strength should be applied in a small area, however after completions of the fan-head it can propagate dynamically through the material at low shear stresses (even below the frictional strength). The fan-mechanism allows explaining all unique features associated with the off-fault cracking process observed in photoelastic experiments [2,3]. In these experiments spontaneous shear ruptures were nucleated in a bonded, precut, inclined and pre-stressed interface by producing a local pressure pulse in a small area. Isochromatic fringe patterns around a shear rupture propagating along bonded interface indicate the following features of the off-fault tensile crack development: tensile cracks nucleate and grow periodically along one side of the interface at a roughly constant angle (about 80 degrees) relative to the shear rupture interface; the tensile crack nucleation takes place some distance behind the rupture tip; with distance from the point of nucleation tensile cracks grow up to a certain length within the rupture head zone; behind this zone static microcracks are left in the wake of the propagating rupture. Unfortunately, the modern technology used in these experiments is not able to identify the shear rupture mechanism itself operated within the narrow rupture interface. However, a special analysis of side effects accompanying the shear rupture propagation (including the off-fault tensile cracking) allows supposing that the failure process was governed by the fan-mechanism. 1. Tarasov, B.G. 2014. Hitherto unknown shear rupture mechanism as a source of instability in intact hard rocks at highly confined compression. Tectonophysics, 621, 69-84. 2. Griffith, W.A., Rosakis, A., Pollard, D.D. and Ko, C.W., 2009. Dynamic rupture experiments elucidate tensile crack development during propagating earthquake ruptures, Geology, pp 795-798. 3. Ngo, D., Huang, Y., Rosakis, A., Griffith, W.A., Pollard D. 2012. Off-fault tensile cracks: A link between geological fault observations, lab experiments, and dynamic rupture models. Journal of Geophysical Research, vol. 117, B01307, doi: 10.1029/2011JB008577 (2012).

Evaluation of Head Orientation and Neck Muscle EMG Signals as Command Inputs to a Human-Computer Interface for Individuals with High Tetraplegia

PubMed Central

Williams, Matthew R.; Kirsch, Robert F.

2013-01-01

We investigated the performance of three user interfaces for restoration of cursor control in individuals with tetraplegia: head orientation, EMG from face and neck muscles, and a standard computer mouse (for comparison). Subjects engaged in a 2D, center-out, Fitts’ Law style task and performance was evaluated using several measures. Overall, head orientation commanded motion resembled mouse commanded cursor motion (smooth, accurate movements to all targets), although with somewhat lower performance. EMG commanded movements exhibited a higher average speed, but other performance measures were lower, particularly for diagonal targets. Compared to head orientation, EMG as a cursor command source was less accurate, was more affected by target direction and was more prone to overshoot the target. In particular, EMG commands for diagonal targets were more sequential, moving first in one direction and then the other rather than moving simultaneous in the two directions. While the relative performance of each user interface differs, each has specific advantages depending on the application. PMID:18990652

Composite Yb:YAG/SiC-prism thin disk laser.

PubMed

Newburgh, G A; Michael, A; Dubinskii, M

2010-08-02

We report the first demonstration of a Yb:YAG thin disk laser wherein the gain medium is intracavity face-cooled through bonding to an optical quality SiC prism. Due to the particular design of the composite bonded Yb:YAG/SiC-prism gain element, the laser beam impinges on all refractive index interfaces inside the laser cavity at Brewster's angles. The laser beam undergoes total internal reflection (TIR) at the bottom of the Yb(10%):YAG thin disk layer in a V-bounce cavity configuration. Through the use of TIR and Brewster's angles, no optical coatings, either anti-reflective (AR) or highly reflective (HR), are required inside the laser cavity. In this first demonstration, the 936.5-nm diode pumped laser performed with approximately 38% slope efficiency at 12 W of quasi-CW (Q-CW) output power at 1030 nm with a beam quality measured at M(2) = 1.5. This demonstration opens up a viable path toward novel thin disk laser designs with efficient double-sided room-temperature heatsinking via materials with the thermal conductivity of copper on both sides of the disk.

Performances of multiprocessor multidisk architectures for continuous media storage

NASA Astrophysics Data System (ADS)

Gennart, Benoit A.; Messerli, Vincent; Hersch, Roger D.

1996-03-01

Multimedia interfaces increase the need for large image databases, capable of storing and reading streams of data with strict synchronicity and isochronicity requirements. In order to fulfill these requirements, we consider a parallel image server architecture which relies on arrays of intelligent disk nodes, each disk node being composed of one processor and one or more disks. This contribution analyzes through bottleneck performance evaluation and simulation the behavior of two multi-processor multi-disk architectures: a point-to-point architecture and a shared-bus architecture similar to current multiprocessor workstation architectures. We compare the two architectures on the basis of two multimedia algorithms: the compute-bound frame resizing by resampling and the data-bound disk-to-client stream transfer. The results suggest that the shared bus is a potential bottleneck despite its very high hardware throughput (400Mbytes/s) and that an architecture with addressable local memories located closely to their respective processors could partially remove this bottleneck. The point- to-point architecture is scalable and able to sustain high throughputs for simultaneous compute- bound and data-bound operations.

Implementing Journaling in a Linux Shared Disk File System

NASA Technical Reports Server (NTRS)

Preslan, Kenneth W.; Barry, Andrew; Brassow, Jonathan; Cattelan, Russell; Manthei, Adam; Nygaard, Erling; VanOort, Seth; Teigland, David; Tilstra, Mike; O'Keefe, Matthew;

COLLISIONS BETWEEN DARK MATTER CONFINED HIGH VELOCITY CLOUDS AND MAGNETIZED GALACTIC DISKS: THE SMITH CLOUD

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

Galyardt, Jason; Shelton, Robin L., E-mail: jeg@uga.edu, E-mail: rls@physast.uga.edu

2016-01-01

The Galaxy’s population of High Velocity Clouds (HVCs) may include a subpopulation that is confined by dark matter minihalos and falling toward the Galactic disk. We present the first magnetohydrodynamic simulational study of dark-matter-dominated HVCs colliding with a weakly magnetized galactic disk. Our HVCs have baryonic masses of 5 × 10{sup 6}M{sub ⊙} and dark matter minihalo masses of 0, 3 × 10{sup 8}, or 1 × 10{sup 9} M{sub ⊙}. They are modeled on the Smith Cloud, which is said to have collided with the disk 70 Myr ago. We find that, in all cases, the cloud’s collision with the galactic disk creates a hole inmore » the disk, completely disperses the cloud, and forms a bubble-shaped structure on the far side of the disk. In contrast, when present, the dark matter minihalo continues unimpeded along its trajectory. Later, as the minihalo passes through the bubble structure and galactic halo, it accretes up to 6.0 × 10{sup 5} M{sub ⊙} in baryonic material, depending on the strengths of the magnetic field and minihalo gravity. These simulations suggest that if the Smith Cloud is associated with a dark matter minihalo and collided with the Galactic disk, the minihalo has accreted the observed gas. However, if the Smith Cloud is dark-matter-free, it is on its first approach toward the disk. These simulations also suggest that the dark matter is most concentrated either at the head of the cloud or near the cloud, depending upon the strength of the magnetic field, a point that could inform indirect dark matter searches.« less

Onboard System Evaluation of Rotors Vibration, Engines (OBSERVE) monitoring System

DTIC Science & Technology

1992-07-01

consists of a Data Acquisiiton Unit (DAU), Control and Display Unit ( CADU ), Universal Tracking Devices (UTD), Remote Cockpit Display (RCD) and a PC...and Display Unit ( CADU ) - The CADU provides data storage and a graphical user interface neccesary to display both the measured data and diagnostic...information. The CADU has an interface to a Credit Card Memory (CCM) which operates similar to a disk drive, allowing the storage of data and programs. The

AUV-12 Sonar Integration and Evaluation

DTIC Science & Technology

2010-02-26

ActiveX control allow the real-time ES MKII data (with embedded navigation data) to be logged to the SBC disk in the ES MKII native XTF format. We...begin transmission to the AUV via the acoustic micro-modem message type 28 that contains the target vessel position, true heading, course over

X-ray Magnetic Linear Dichroism of Fe-Ni Alloys on Cu(111)

DTIC Science & Technology

2001-04-01

the study of magnetism and magnetic materials. This control allows for the study of the relationship between magnetic and structural properties for...effect in NiFe /Cu systems that are relevant to magnetic disk drive heads. Using core-level photoelectron spectroscopies on magnetized samples allows

Spacecraft optical disk recorder memory buffer control

NASA Technical Reports Server (NTRS)

Hodson, Robert F.

1992-01-01

The goal of this project is to develop an Application Specific Integrated Circuit (ASIC) for use in the control electronics of the Spacecraft Optical Disk Recorder (SODR). Specifically, this project is to design an extendable memory buffer controller ASIC for rate matching between a system Input/Output port and the SODR's device interface. The aforementioned goal can be partitioned into the following sub-goals: (1) completion of ASIC design and simulation (on-going via ASEE fellowship); (2) ASIC Fabrication (at ASIC manufacturer); and (3) ASIC Testing (NASA/LaRC, Christopher Newport University).

Spin-Valve and Spin-Tunneling Devices: Read Heads, MRAMs, Field Sensors

NASA Astrophysics Data System (ADS)

Freitas, P. P.

Hard disk magnetic data storage is increasing at a steady state in terms of units sold, with 144 million drives sold in 1998 (107 million for desktops, 18 million for portables, and 19 million for enterprise drives), corresponding to a total business of 34 billion US [1]. The growing need for storage coming from new PC operating systems, INTERNET applications, and a foreseen explosion of applications connected to consumer electronics (digital TV, video, digital cameras, GPS systems, etc.), keep the magnetics community actively looking for new solutions, concerning media, heads, tribology, and system electronics. Current state of the art disk drives (January 2000), using dual inductive-write, magnetoresistive-read (MR) integrated heads reach areal densities of 15 to 23 bit/μm2, capable of putting a full 20 GB in one platter (a 2 hour film occupies 10 GB). Densities beyond 80 bit/μm2 have already been demonstrated in the laboratory (Fujitsu 87 bit/μm2-Intermag 2000, Hitachi 81 bit/μm2, Read-Rite 78 bit/μ m2, Seagate 70 bit/μ m2 - all the last three demos done in the first 6 months of 2000, with IBM having demonstrated 56 bit/μ m2 already at the end of 1999). At densities near 60 bit/μm2, the linear bit size is sim 43 nm, and the width of the written tracks is sim 0.23 μm. Areal density in commercial drives is increasing steadily at a rate of nearly 100% per year [1], and consumer products above 60 bit/μm2 are expected by 2002. These remarkable achievements are only possible by a stream of technological innovations, in media [2], write heads [3], read heads [4], and system electronics [5]. In this chapter, recent advances on spin valve materials and spin valve sensor architectures, low resistance tunnel junctions and tunnel junction head architectures will be addressed.

The GUI OPAC: Approach with Caution.

ERIC Educational Resources Information Center

Hildreth, Charles R.

1995-01-01

Discusses the graphical user interface (GUI) online public access catalog (OPAC), a user interface that uses images to represent options. Topics include user interface design for information retrieval; designing effective bibliographic displays, including subject headings; two design principles; and what GUIs can bring to OPACs. (LRW)

Equivalent Circuit Model of Low-Frequency Magnetoelectric Effect in Disk-Type Terfenol-D/PZT Laminate Composites Considering a New Interface Coupling Factor.

PubMed

Lou, Guofeng; Yu, Xinjie; Lu, Shihua

2017-06-15

This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb 0.3 Dy 0.7 Fe 1.92 )/PZT (Pb(Zr,Ti)O₃) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface coupling factor k c , which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing k c for the transverse ME voltage coefficient α v and the optimum thickness ratio n optim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface coupling factor acted as an ideal transformer. To explore the influence of mechanical load on the interface coupling factor k c , two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface coupling factors determined from the measured α v and the DC bias magnetic field H bias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for k c = 0.11 and 0.56 for k c = 0.08. Both the theoretical ME voltage coefficient α v and optimum thickness ratio n optim containing k c agreed well with the measured data, verifying the reasonability and correctness for the introduction of k c in the modified equivalent circuit model.

Equivalent Circuit Model of Low-Frequency Magnetoelectric Effect in Disk-Type Terfenol-D/PZT Laminate Composites Considering a New Interface Coupling Factor

PubMed Central

Lou, Guofeng; Yu, Xinjie; Lu, Shihua

2017-01-01

This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb0.3Dy0.7Fe1.92)/PZT (Pb(Zr,Ti)O3) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface coupling factor kc, which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing kc for the transverse ME voltage coefficient αv and the optimum thickness ratio noptim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface coupling factor acted as an ideal transformer. To explore the influence of mechanical load on the interface coupling factor kc, two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface coupling factors determined from the measured αv and the DC bias magnetic field Hbias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for kc = 0.11 and 0.56 for kc = 0.08. Both the theoretical ME voltage coefficient αv and optimum thickness ratio noptim containing kc agreed well with the measured data, verifying the reasonability and correctness for the introduction of kc in the modified equivalent circuit model. PMID:28617352

The Dragonfly Nearby Galaxies Survey. IV. A Giant Stellar Disk in NGC 2841

NASA Astrophysics Data System (ADS)

Zhang, Jielai; Abraham, Roberto; van Dokkum, Pieter; Merritt, Allison; Janssens, Steven

2018-03-01

Neutral gas is commonly believed to dominate over stars in the outskirts of galaxies, and investigations of the disk-halo interface are generally considered to be in the domain of radio astronomy. This may simply be a consequence of the fact that deep H I observations typically probe to a lower-mass surface density than visible wavelength data. This paper presents low-surface-brightness, optimized visible wavelength observations of the extreme outskirts of the nearby spiral galaxy NGC 2841. We report the discovery of an enormous low-surface brightness stellar disk in this object. When azimuthally averaged, the stellar disk can be traced out to a radius of ∼70 kpc (5 R 25 or 23 inner disk scale lengths). The structure in the stellar disk traces the morphology of H I emission and extended UV emission. Contrary to expectations, the stellar mass surface density does not fall below that of the gas mass surface density at any radius. In fact, at all radii greater than ∼20 kpc, the ratio of the stellar mass to gas mass surface density is a constant 3:1. Beyond ∼30 kpc, the low-surface-brightness stellar disk begins to warp, which may be an indication of a physical connection between the outskirts of the galaxy and infall from the circumgalactic medium. A combination of stellar migration, accretion, and in situ star formation might be responsible for building up the outer stellar disk, but whatever mechanisms formed the outer disk must also explain the constant ratio between stellar and gas mass in the outskirts of this galaxy.

High resolution optical shaft encoder for motor speed control based on an optical disk pick-up

NASA Astrophysics Data System (ADS)

Yeh, Wei-Hung; Bletscher, Warren; Mansuripur, M.

1998-08-01

Using a three-beam optical pick-up from a compact disk player and a flexible, shaft-mounted diffraction grating, we obtain information about the rotation speed and angular position of the motor's spindle. This information may be used for feedback to the motor for smooth operation. Due to the small size of the focused spot and the built-in auto-focus mechanism of the optical head, the proposed encoder can achieve submicrometer resolution. With high resolution, reliable operation, and low-cost elements, the proposed method is suitable for rotary and linear motion control where accurate positioning of an object is required.

Three-axis lever actuator with flexure hinges for an optical disk system

NASA Astrophysics Data System (ADS)

Han, Chang-Soo; Kim, Soo-Hyun

2002-10-01

A three-axis lever actuator with a flexure hinge has been designed and fabricated. This actuator is driven by electromagnetic force based on a coil-magnet system and can be used as a high precision actuator and, especially as a pickup head actuator in optical disks. High precision and low sensitivity to external vibration are the major advantages of this lever actuator. An analysis model was found and compared to the finite element method. Dynamic characteristics of the three-axis lever actuator were measured. The results are in very close agreement to those predicted by the model and finite element analysis.

Chemical and physical characterization of the first stages of protoplanetary disk formation

NASA Astrophysics Data System (ADS)

Hincelin, Ugo

2012-12-01

Low mass stars, like our Sun, are born from the collapse of a molecular cloud. The matter falls in the center of the cloud, creating a protoplanetary disk surrounding a protostar. Planets and other Solar System bodies will be formed in the disk. The chemical composition of the interstellar matter and its evolution during the formation of the disk are important to better understand the formation process of these objects. I studied the chemical and physical evolution of this matter, from the cloud to the disk, using the chemical gas-grain code Nautilus. A sensitivity study to some parameters of the code (such as elemental abundances and parameters of grain surface chemistry) has been done. More particularly, the updates of rate coefficients and branching ratios of the reactions of our chemical network showed their importance, such as on the abundances of some chemical species, and on the code sensitivity to others parameters. Several physical models of collapsing dense core have also been considered. The more complex and solid approach has been to interface our chemical code with the radiation-magneto-hydrodynamic model of stellar formation RAMSES, in order to model in three dimensions the physical and chemical evolution of a young disk formation. Our study showed that the disk keeps imprints of the past history of the matter, and so its chemical composition is sensitive to the initial conditions.

Two chemically similar stellar overdensities on opposite sides of the plane of the Galactic disk

DOE PAGES

Bergemann, Maria; Sesar, Branimir; Cohen, Judith G.; ...

2018-02-26

Our Galaxy is thought to have undergone an active evolutionary history dominated by star formation, the accretion of cold gas, and, in particular, mergers up to 10 gigayear ago. The stellar halo reveals rich fossil evidence of these interactions in the form of stellar streams, substructures, and chemically distinct stellar components. The impact of dwarf galaxy mergers on the content and morphology of the Galactic disk is still being explored. Recent studies have identified kinematically distinct stellar substructures and moving groups, which may have extragalactic origin. However, there is mounting evidence that stellar overdensities at the outer disk/halo interface couldmore » have been caused by the interaction of a dwarf galaxy with the disk. Here we report detailed spectroscopic analysis of 14 stars drawn from two stellar overdensities, each lying about 5 kiloparsecs above and below the Galactic plane - locations suggestive of association with the stellar halo. However, we find that the chemical compositions of these stars are almost identical, both within and between these groups, and closely match the abundance patterns of the Milky Way disk stars. This study hence provides compelling evidence that these stars originate from the disk and the overdensities they are part of were created by tidal interactions of the disk with passing or merging dwarf galaxies.« less

Hot SPOT Eclipses in Dwarf Novae

NASA Astrophysics Data System (ADS)

Smak, J.

1996-10-01

Eclipses of the hot spot in four dwarf novae: U Gem, IP Peg, Z Cha, and OY Car are re-analyzed, assuming two models for the shape of the spot. In Model 1 an elliptical spot is assumed, with the semi-axes s_a in the orbital plane and s_b perpendicular to the orbital plane, its center located on the stream trajectory. The results show that such an ellipse is, within errors, tangent to the disk's circumference. In all four cases the resulting dimensions of the spot s_a are larger than the theoretical cross-section of the stream. Accordingly, in Model2 the spot is assumed to consist of a head, centered on the stream trajectory, and a tail, extending downstream, ie., along disk's circumference. In some cases the resulting parameters, eg., mass ratios or disk radii, differ significantly from those obtained with Model 1.

Circling motion and screen edges as an alternative input method for on-screen target manipulation.

PubMed

Ka, Hyun W; Simpson, Richard C

2017-04-01

To investigate a new alternative interaction method, called circling interface, for manipulating on-screen objects. To specify a target, the user makes a circling motion around the target. To specify a desired pointing command with the circling interface, each edge of the screen is used. The user selects a command before circling the target. To evaluate the circling interface, we conducted an experiment with 16 participants, comparing the performance on pointing tasks with different combinations of selection method (circling interface, physical mouse and dwelling interface) and input device (normal computer mouse, head pointer and joystick mouse emulator). A circling interface is compatible with many types of pointing devices, not requiring physical activation of mouse buttons, and is more efficient than dwell-clicking. Across all common pointing operations, the circling interface had a tendency to produce faster performance with a head-mounted mouse emulator than with a joystick mouse. The performance accuracy of the circling interface outperformed the dwelling interface. It was demonstrated that the circling interface has the potential as another alternative pointing method for selecting and manipulating objects in a graphical user interface. Implications for Rehabilitation A circling interface will improve clinical practice by providing an alternative pointing method that does not require physically activating mouse buttons and is more efficient than dwell-clicking. The Circling interface can also work with AAC devices.

Magnetocentrifugally Driven Flows from Young Stars and Disks. IV. The Accretion Funnel and Dead Zone

NASA Astrophysics Data System (ADS)

Ostriker, Eve C.; Shu, Frank H.

1995-07-01

We formulate the time-steady, axisymmetric problem of stellar magnetospheric inflow of gas from a surrounding accretion disk. The computational domain is bounded on the outside by a surface of given shape containing the open field lines associated with an induced disk wind. The mechanism for this wind has been investigated in previous publications in this journal. Our zeroth-order solution incorporates an acceptable accounting of the pressure balance between the magnetic field lines loaded with accreting gas (funnel flow) and those empty of matter (dead zone). In comparison with previous models, our funnel-flow/dead-zone solution has the following novel features: (1) Because of a natural tendency for the trapped stellar magnetic flux to pinch toward the corotation radius Rx (X-point of the effective potential), most of the interesting magnetohydrodynamics is initiated within a small neighborhood of Rx (X-region), where the Keplerian angular speed of rotation in the disk equals the spin rate of the star. (2) Unimpeded funnel flow from the inner portion of the X-region to the star can occur when the amount of trapped magnetic flux equals or exceeds 1.5 times the unperturbed dipole flux that would lie outside Rx in the absence of an accretion disk. (3). Near the equatorial plane, radial infall from the X-point is terminated at a "kink" point Rk = 0.74Rx that deflects the flow away from the midplane, mediating thereby between the field topology imposed by a magnetic fan of trapped flux at Rx and the geometry of a strong stellar dipole. (4) The excess angular momentum of accretion that would otherwise spin up the star rapidly is deposited by the magnetic torques of the funnel flow into the inner portion of the X-region of the disk. (5) An induced disk wind arises in the outer portion of the .X-region, where the stellar field lines have been blown open, and removes whatever excess angular momentum that viscous torques do not transport to the outer disk. (6) The interface between open field lines loaded with outflowing matter (connected to the disk) and those not loaded (connected to the star) forms a "helmet streamer," along which major mass-ejection and reconnection events may arise in response to changing boundary conditions (e.g., stellar magnetic cycles), much the way that such events occur in the active Sun. (7) Pressure balance across the dead-zone/wind interface will probably yield an asymptotically vertical (i.e., "jetlike") trajectory for the matter ejected along the helmet streamer, but mathematical demonstration of this fact is left for future studies. (8) In steady state the overall balance of angular momentum in the star/disk/ magnetosphere system fixes the fractions, f and 1 - f, of the disk mass accretion rate into the X-region carried away, respectively, by the wind and funnel flows.

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

Bergemann, Maria; Sesar, Branimir; Cohen, Judith G.

Our Galaxy is thought to have undergone an active evolutionary history dominated by star formation, the accretion of cold gas, and, in particular, mergers up to 10 gigayear ago. The stellar halo reveals rich fossil evidence of these interactions in the form of stellar streams, substructures, and chemically distinct stellar components. The impact of dwarf galaxy mergers on the content and morphology of the Galactic disk is still being explored. Recent studies have identified kinematically distinct stellar substructures and moving groups, which may have extragalactic origin. However, there is mounting evidence that stellar overdensities at the outer disk/halo interface couldmore » have been caused by the interaction of a dwarf galaxy with the disk. Here we report detailed spectroscopic analysis of 14 stars drawn from two stellar overdensities, each lying about 5 kiloparsecs above and below the Galactic plane - locations suggestive of association with the stellar halo. However, we find that the chemical compositions of these stars are almost identical, both within and between these groups, and closely match the abundance patterns of the Milky Way disk stars. This study hence provides compelling evidence that these stars originate from the disk and the overdensities they are part of were created by tidal interactions of the disk with passing or merging dwarf galaxies.« less

The Development of a Portable Hard Disk Encryption/Decryption System with a MEMS Coded Lock

PubMed Central

Zhang, Weiping; Chen, Wenyuan; Tang, Jian; Xu, Peng; Li, Yibin; Li, Shengyong

2009-01-01

In this paper, a novel portable hard-disk encryption/decryption system with a MEMS coded lock is presented, which can authenticate the user and provide the key for the AES encryption/decryption module. The portable hard-disk encryption/decryption system is composed of the authentication module, the USB portable hard-disk interface card, the ATA protocol command decoder module, the data encryption/decryption module, the cipher key management module, the MEMS coded lock controlling circuit module, the MEMS coded lock and the hard disk. The ATA protocol circuit, the MEMS control circuit and AES encryption/decryption circuit are designed and realized by FPGA(Field Programmable Gate Array). The MEMS coded lock with two couplers and two groups of counter-meshing-gears (CMGs) are fabricated by a LIGA-like process and precision engineering method. The whole prototype was fabricated and tested. The test results show that the user's password could be correctly discriminated by the MEMS coded lock, and the AES encryption module could get the key from the MEMS coded lock. Moreover, the data in the hard-disk could be encrypted or decrypted, and the read-write speed of the dataflow could reach 17 MB/s in Ultra DMA mode. PMID:22291566

76 FR 79171 - Pesticide Products; Receipt of Applications To Register New Uses

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-21

... disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot... docket ID number and other identifying information (subject heading, Federal Register date and page... Name and Address: Arysta LifeScience, North America LLC., 15401 Weston Parkway, Suite 150, Cary, NC...

Feasibility of Equivalent Dipole Models for Electroencephalogram-Based Brain Computer Interfaces.

PubMed

Schimpf, Paul H

2017-09-15

This article examines the localization errors of equivalent dipolar sources inverted from the surface electroencephalogram in order to determine the feasibility of using their location as classification parameters for non-invasive brain computer interfaces. Inverse localization errors are examined for two head models: a model represented by four concentric spheres and a realistic model based on medical imagery. It is shown that the spherical model results in localization ambiguity such that a number of dipolar sources, with different azimuths and varying orientations, provide a near match to the electroencephalogram of the best equivalent source. No such ambiguity exists for the elevation of inverted sources, indicating that for spherical head models, only the elevation of inverted sources (and not the azimuth) can be expected to provide meaningful classification parameters for brain-computer interfaces. In a realistic head model, all three parameters of the inverted source location are found to be reliable, providing a more robust set of parameters. In both cases, the residual error hypersurfaces demonstrate local minima, indicating that a search for the best-matching sources should be global. Source localization error vs. signal-to-noise ratio is also demonstrated for both head models.

Conservative treatment of a patient with previously unresponsive whiplash-associated disorders using clinical biomechanics of posture rehabilitation methods.

PubMed

Ferrantelli, Joseph R; Harrison, Deed E; Harrison, Donald D; Stewart, Denis

2005-01-01

To describe the treatment of a patient with chronic whiplash-associated disorders (WADs) previously unresponsive to multiple physical therapy and chiropractic treatments, which resolved following Clinical Biomechanics of Posture (CBP) rehabilitation methods. A 40-year-old man involved in a high-speed rear-impact collision developed chronic WADs including cervicothoracic, shoulder, and arm pain and headache. The patient was diagnosed with a confirmed chip fracture of the C5 vertebra and cervical and thoracic disk herniations. He was treated with traditional chiropractic and physical therapy modalities but experienced only temporary symptomatic reduction and was later given a whole body permanent impairment rating of 33% by an orthopedic surgeon. The patient was treated with CBP mirror-image cervical spine adjustments, exercise, and traction to reduce forward head posture and cervical kyphosis. A presentation of abnormal head protrusion resolved and cervical kyphosis returned to lordosis posttreatment. His initial neck disability index was 46% and 0% at the end of care. Verbal pain rating scales also improved for neck pain (from 5/10 to 0/10). A patient with chronic WADs and abnormal head protrusion, cervical kyphosis, and disk herniation experienced an improvement in symptoms and function after the use of CBP rehabilitation protocols when other traditional chiropractic and physical therapy procedures showed little or no lasting improvement.

An Overview of U.S. Trends in Educational Software Design.

ERIC Educational Resources Information Center

Colvin, Linda B.

1989-01-01

Describes trends in educational software design in the United States for elementary and secondary education. Highlights include user-friendly software; learner control; interfacing the computer with other media, including television, telecommunications networks, and optical disk technology; microworlds; graphics; word processing; database…

Old PCs: Upgrade or Abandon?

ERIC Educational Resources Information Center

Perez, Ernest

1997-01-01

Examines the practical realities of upgrading Intel personal computers in libraries, considering budgets and technical personnel availability. Highlights include adding RAM; putting in faster processor chips, including clock multipliers; new hard disks; CD-ROM speed; motherboards and interface cards; cost limits and economic factors; and…

Whither the White Knight: CDROM in Technical Services.

ERIC Educational Resources Information Center

Campbell, Brian

1987-01-01

Outlines evaluative criteria and compares optical data disk products used in library technical processes, including bibliographic records for cataloging, acquisition databases, and local public access catalogs. An extensive table provides information on specific products, including updates, interfaces, edit screens, installation help, manuals,…

Focused Flow During Infiltration Into Ethanol-Contaminated Unsaturated Porous Media

NASA Astrophysics Data System (ADS)

Jazwiec, A.; Smith, J. E.

2017-12-01

The increasing commercial and industrial use of ethanol, e.g. in biofuels, has generated increased incidents of vadose zone contamination by way of ethanol spills and releases. This has increased the interest in better understanding behaviors of ethanol in unsaturated porous media and it's multiphase interactions in the vadose zone. This study uses highly controlled laboratory experiments in a 2-D (0.6mx0.6mx0.01m) flow cell to investigate water infiltration behaviors into ethanol-contaminated porous media. Ethanol and water were applied by either constant head or constant flux methods onto the surface of sands homogenously packed into the flow cell. The constant flux experiments at both low and high application rates were conducted using a rainulator with a row of hypodermic needles connected to a peristaltic pump. The constant head experiments were conducted using an 8cm diameter tension disk infiltrometer set to both low and high tensions. The presence of ethanol contamination generated solute-dependent capillarity induced focused flow (SCIFF) of water infiltration, which was primarily due to decreases in interfacial tensions at the air-liquid interfaces in the unsaturated sands as a function of ethanol concentration. SCIFF was clearly expressed as an unsaturated water flow phenomenon comprised of narrowly focused vertical flow fingers of water within the initially ethanol contaminated porous media. Using analyses of photos and video, comparisons were made between constant flux and constant head application methods. Further comparisons were made between low and high infiltration rates and the two sand textures used. A high degree of sensitivity to minor heterogeneity in relatively homogeneous sands was also observed. The results of this research have implications for rainfall infiltration into ethanol contaminated vadose zones expressing SCIFF, including implications for associated mass fluxes and the nature of flushing of ethanol from the unsaturated zone to groundwaters.

Experimental conical-head abutment screws on the microbial leakage through the implant-abutment interface: an in vitro analysis using target-specific DNA probes.

PubMed

Pita, Murillo S; do Nascimento, Cássio; Dos Santos, Carla G P; Pires, Isabela M; Pedrazzi, Vinícius

2017-07-01

The aim of this in vitro study was to identify and quantify up to 38 microbial species from human saliva penetrating through the implant-abutment interface in two different implant connections, external hexagon and tri-channel internal connection, both with conventional flat-head or experimental conical-head abutment screws. Forty-eight two-part implants with external hexagon (EH; n = 24) or tri-channel internal (TI; n = 24) connections were investigated. Abutments were attached to implants with conventional flat-head or experimental conical-head screws. After saliva incubation, Checkerboard DNA-DNA hybridization was used to identify and quantify up to 38 bacterial colonizing the internal parts of the implants. Kruskal-Wallis test followed by Bonferroni's post-tests for multiple comparisons was used for statistical analysis. Twenty-four of thirty-eight species, including putative periodontal pathogens, were found colonizing the inner surfaces of both EH and TI implants. Peptostreptococcus anaerobios (P = 0.003), Prevotella melaninogenica (P < 0.0001), and Candida dubliniensis (P < 0.0001) presented significant differences between different groups. Means of total microbial count (×10 4 , ±SD) for each group were recorded as follows: G1 (0.27 ± 2.04), G2 (0 ± 0), G3 (1.81 ± 7.50), and G4 (0.35 ± 1.81). Differences in the geometry of implant connections and abutment screws have impacted the microbial leakage through the implant-abutment interface. Implants attached with experimental conical-head abutment screws showed lower counts of microorganisms when compared with conventional flat-head screws. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The Role of Interface on the Impact Characteristics and Cranial Fracture Patterns Using the Immature Porcine Head Model.

PubMed

Deland, Trevor S; Niespodziewanski, Emily; Fenton, Todd W; Haut, Roger C

2016-01-01

The role of impact interface characteristics on the biomechanics and patterns of cranial fracture has not been investigated in detail, and especially for the pediatric head. In this study, infant porcine skulls aged 2-19 days were dropped with an energy to cause fracturing onto four surfaces varying in stiffness from a rigid plate to one covered with plush carpeting. Results showed that heads dropped onto the rigid surface produced more extensive cranial fracturing than onto carpeted surfaces. Contact forces generated at fracture initiation and the overall maximum contact forces were generally lower for the rigid than carpeted impacts. While the degree of cranial fracturing from impacts onto the heavy carpeted surface was comparable to that of lower-energy rigid surface impacts, there were fewer diastatic fractures. This suggests that characteristics of the cranial fracture patterns may be used to differentiate energy level from impact interface in pediatric forensic cases. © 2015 American Academy of Forensic Sciences.

The Reovirus Sigmal Aspartic Acid Sandwich: A Trimerization Motif Poised for Conformational Change

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

Schelling,P.; Guglielml, K.; Kirchner, E.

2007-01-01

Reovirus attachment protein {sigma}1 mediates engagement of receptors on the surface of target cells and undergoes dramatic conformational rearrangements during viral disassembly in the endocytic pathway. The {sigma}1 protein is a filamentous, trimeric molecule with a globular {beta}-barrel head domain. An unusual cluster of aspartic acid residues sandwiched between hydrophobic tyrosines is located at the {sigma}1 subunit interface. A 1.75 {angstrom} structure of the {sigma}1 head domain now reveals two water molecules at the subunit interface that are held strictly in position and interact with neighboring residues. Structural and biochemical analyses of mutants affecting the aspartic acid sandwich indicate thatmore » these residues and the corresponding chelated water molecules act as a plug to block the free flow of solvent and stabilize the trimer. This arrangement of residues at the {sigma}1 head trimer interface illustrates a new protein design motif that may confer conformational mobility during cell entry.« less

A theoretical consideration of ion size effects on the electric double layer and voltammetry of nanometer-sized disk electrodes.

PubMed

Gao, Yu; Liu, Yuwen; Chen, Shengli

2016-12-12

Considering that an electric-double-layer (EDL) structure may significantly impact on the mass transport and charge transfer kinetics at the interfaces of nanometer-sized electrodes, while EDL structures could be altered by the finite sizes of electrolyte and redox ions, the possible effects of ion sizes on EDL structures and voltammetric responses of nanometer-sized disk (nanodisk) electrodes are investigated. Modified Boltzmann and Nernst-Planck (NP) equations, which include the influence of the finite ion volumes, are combined with the Poisson equation and modified Butler-Volmer equation to gain knowledge on how the finite sizes of ions and the nanometer sizes of electrodes may couple with each other to affect the structures and reactivities of a nanoscale electrochemical interface. Two typical ion radii, 0.38 nm and 0.68 nm, which could represent the sizes of the commonly used aqueous electrolyte ions (e.g., the solvated K + ) and the organic electrolyte ions (e.g., the solvated TEA + ) respectively, are considered. The finite size of ions can result in decreased screening of electrode charges, therefore magnifying EDL effects on the ion transport and the electron transfer at electrochemical interfaces. This finite size effect of ions becomes more pronounced for larger ions and at smaller electrodes as the electrode radii is larger than 10 nm. For electrodes with radii smaller than 10 nm, however, the ion size effect may be less pronounced with decreasing the electrode size. This can be explained in terms of the increased edge effect of disk electrodes at nanometer scales, which could relax the ion crowding at/near the outer Helmholtz plane. The conditions and situations under which the ion sizes may have a significant effect on the voltammetry of electrodes are discussed.

An evaluation of unisensory and multisensory adaptive flight-path navigation displays

NASA Astrophysics Data System (ADS)

Moroney, Brian W.

1999-11-01

The present study assessed the use of unimodal (auditory or visual) and multimodal (audio-visual) adaptive interfaces to aid military pilots in the performance of a precision-navigation flight task when they were confronted with additional information-processing loads. A standard navigation interface was supplemented by adaptive interfaces consisting of either a head-up display based flight director, a 3D virtual audio interface, or a combination of the two. The adaptive interfaces provided information about how to return to the pathway when off course. Using an advanced flight simulator, pilots attempted two navigation scenarios: (A) maintain proper course under normal flight conditions and (B) return to course after their aircraft's position has been perturbed. Pilots flew in the presence or absence of an additional information-processing task presented in either the visual or auditory modality. The additional information-processing tasks were equated in terms of perceived mental workload as indexed by the NASA-TLX. Twelve experienced military pilots (11 men and 1 woman), naive to the purpose of the experiment, participated in the study. They were recruited from Wright-Patterson Air Force Base and had a mean of 2812 hrs. of flight experience. Four navigational interface configurations, the standard visual navigation interface alone (SV), SV plus adaptive visual, SV plus adaptive auditory, and SV plus adaptive visual-auditory composite were combined factorially with three concurrent tasks (CT), the no CT, the visual CT, and the auditory CT, a completely repeated measures design. The adaptive navigation displays were activated whenever the aircraft was more than 450 ft off course. In the normal flight scenario, the adaptive interfaces did not bolster navigation performance in comparison to the standard interface. It is conceivable that the pilots performed quite adequately using the familiar generic interface under normal flight conditions and hence showed no added benefit of the adaptive interfaces. In the return-to-course scenario, the relative advantages of the three adaptive interfaces were dependent upon the nature of the CT in a complex way. In the absence of a CT, recovery heading performance was superior with the adaptive visual and adaptive composite interfaces compared to the adaptive auditory interface. In the context of a visual CT, recovery when using the adaptive composite interface was superior to that when using the adaptive visual interface. Post-experimental inquiry indicated that when faced with a visual CT, the pilots used the auditory component of the multimodal guidance display to detect gross heading errors and the visual component to make more fine-grained heading adjustments. In the context of the auditory CT, navigation performance using the adaptive visual interface tended to be superior to that when using the adaptive auditory interface. Neither CT performance nor NASA-TLX workload level was influenced differentially by the interface configurations. Thus, the potential benefits associated with the proposed interfaces appear to be unaccompanied by negative side effects involving CT interference and workload. The adaptive interface configurations were altered without any direct input from the pilot. Thus, it was feared that pilots might reject the activation of interfaces independent of their control. However, pilots' debriefing comments about the efficacy of the adaptive interface approach were very positive. (Abstract shortened by UMI.)

High density tape/head interface study

NASA Technical Reports Server (NTRS)

Csengery, L. C.

1983-01-01

The high energy (H sub c approximately or = to 650 oersteds) tapes and high track density (84 tracks per inch) heads investigated had, as its goal, the definition of optimum combinations of head and tape, including the control required of their interfacial dynamics that would enable the manufacture of high rate (150 Mbps) digital tape recorders for unattended space flight.

Black Hole Disk Accretion in Supernovae

NASA Astrophysics Data System (ADS)

Mineshige, Shin; Nomura, Hideko; Hirose, Masahito; Nomoto, Ken'ichi; Suzuki, Tomoharu

1997-11-01

Massive stars in a certain mass range may form low-mass black holes after supernova explosions. In such massive stars, fallback of ~0.1 M⊙ materials onto a black hole is expected because of a deep gravitational potential or a reverse shock propagating back from the outer composition interface. We study hydrodynamical disk accretion onto a newborn low-mass black hole in a supernova using the smoothed particle hydrodynamics method. If the progenitor was rotating before the explosion, the fallback material should have a certain amount of angular momentum with respect to the black hole, thus forming an accretion disk. The disk material will eventually accrete toward the central object because of viscosity at a supercritical accretion rate, Ṁ/Ṁcrit>106, for the first several tens of days. (Here, Ṁcrit is the Eddington luminosity divided by c2.) We then expect that such an accretion disk is optically thick and advection dominated; that is, the disk is so hot that the produced energy and photons are advected inward rather than being radiated away. Thus, the disk luminosity is much less than the Eddington luminosity. The disk becomes hot and dense; for Ṁ/Ṁcrit~106, for example, T ~ 109(αvis/0.01)-1/4 K and ρ ~ 103(αvis/0.01)-1 g cm-3 (with αvis being the viscosity parameter) in the vicinity of the black hole. Depending on the material mixing, some interesting nucleosynthesis processes via rapid proton and alpha-particle captures are expected even for reasonable viscosity magnitudes (αvis ~ 0.01), and some of them could be ejected in a disk wind or a jet without being swallowed by the black hole.

Computer Program Development Specification for Tactical Interface System.

DTIC Science & Technology

1981-07-31

CNTL CNTL TO ONE VT~i.AE CR1 & TWELVE VT100 LCARD READER VIDEO TERMINALS, SIX LA12O) HARD- COPY TERMINALS, & VECTOR GRAPHICS RPO % TERMINAL 17%M DISK...this data into the TIS para - .. meter tables in the TISGBL common area. ICEHANDL will send test interface ICE to PSS in one of two modes: perio- dically...STOPCauss te TI sotwar toexit ,9.*9~ .r .~ * ~%.’h .9~ .. a .~ .. a. 1 , , p * % .’.-:. .m 7 P : SDSS-MMP-BI ." 31 July 1981 TCL commands authorized

Interfacing the Experimenter to the Computer: Languages for Psychologists

ERIC Educational Resources Information Center

Wood, Ronald W.; And Others

1975-01-01

An examination and comparison of the computer languages which behavioral scientists are most likely to use: SCAT, INTERACT, SKED, OS/8 Fortran IV, RT11/Fortran, RSX-11M, Data General's Real-Time; Disk Operating System and its Fortran, and interpretative Languages. (EH)

Performance of the Galley Parallel File System

NASA Technical Reports Server (NTRS)

Nieuwejaar, Nils; Kotz, David

1996-01-01

As the input/output (I/O) needs of parallel scientific applications increase, file systems for multiprocessors are being designed to provide applications with parallel access to multiple disks. Many parallel file systems present applications with a conventional Unix-like interface that allows the application to access multiple disks transparently. This interface conceals the parallism within the file system, which increases the ease of programmability, but makes it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. Furthermore, most current parallel file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic parallel workloads. Initial experiments, reported in this paper, indicate that Galley is capable of providing high-performance 1/O to applications the applications that rely on them. In Section 3 we describe that access data in patterns that have been observed to be common.

Two chemically similar stellar overdensities on opposite sides of the plane of the Galactic disk.

PubMed

Bergemann, Maria; Sesar, Branimir; Cohen, Judith G; Serenelli, Aldo M; Sheffield, Allyson; Li, Ting S; Casagrande, Luca; Johnston, Kathryn V; Laporte, Chervin F P; Price-Whelan, Adrian M; Schönrich, Ralph; Gould, Andrew

2018-03-15

Our Galaxy is thought to have an active evolutionary history, dominated over the past ten billion years or so by star formation, the accretion of cold gas and, in particular, the merging of clumps of baryonic and dark matter. The stellar halo-the faint, roughly spherical component of the Galaxy-reveals rich 'fossil' evidence of these interactions, in the form of stellar streams, substructures and chemically distinct stellar components. The effects of interactions with dwarf galaxies on the content and morphology of the Galactic disk are still being explored. Recent studies have identified kinematically distinct stellar substructures and moving groups of stars in our Galaxy, which may have extragalactic origins. There is also mounting evidence that stellar overdensities (regions with greater-than-average stellar density) at the interface between the outer disk and the halo could have been caused by the interaction of a dwarf galaxy with the disk. Here we report a spectroscopic analysis of 14 stars from two stellar overdensities, each lying about five kiloparsecs above or below the Galactic plane-locations suggestive of an association with the stellar halo. We find that the chemical compositions of these two groups of stars are almost identical, both within and between these overdensities, and closely match the abundance patterns of stars in the Galactic disk. We conclude that these stars came from the disk, and that the overdensities that they are part of were created by tidal interactions of the disk with passing or merging dwarf galaxies.

Two chemically similar stellar overdensities on opposite sides of the plane of the Galactic disk

NASA Astrophysics Data System (ADS)

Bergemann, Maria; Sesar, Branimir; Cohen, Judith G.; Serenelli, Aldo M.; Sheffield, Allyson; Li, Ting S.; Casagrande, Luca; Johnston, Kathryn V.; Laporte, Chervin F. P.; Price-Whelan, Adrian M.; Schönrich, Ralph; Gould, Andrew

2018-03-01

Our Galaxy is thought to have an active evolutionary history, dominated over the past ten billion years or so by star formation, the accretion of cold gas and, in particular, the merging of clumps of baryonic and dark matter. The stellar halo—the faint, roughly spherical component of the Galaxy—reveals rich ‘fossil’ evidence of these interactions, in the form of stellar streams, substructures and chemically distinct stellar components. The effects of interactions with dwarf galaxies on the content and morphology of the Galactic disk are still being explored. Recent studies have identified kinematically distinct stellar substructures and moving groups of stars in our Galaxy, which may have extragalactic origins. There is also mounting evidence that stellar overdensities (regions with greater-than-average stellar density) at the interface between the outer disk and the halo could have been caused by the interaction of a dwarf galaxy with the disk. Here we report a spectroscopic analysis of 14 stars from two stellar overdensities, each lying about five kiloparsecs above or below the Galactic plane—locations suggestive of an association with the stellar halo. We find that the chemical compositions of these two groups of stars are almost identical, both within and between these overdensities, and closely match the abundance patterns of stars in the Galactic disk. We conclude that these stars came from the disk, and that the overdensities that they are part of were created by tidal interactions of the disk with passing or merging dwarf galaxies.

VEVI: A Virtual Reality Tool For Robotic Planetary Explorations

NASA Technical Reports Server (NTRS)

Piguet, Laurent; Fong, Terry; Hine, Butler; Hontalas, Phil; Nygren, Erik

1994-01-01

The Virtual Environment Vehicle Interface (VEVI), developed by the NASA Ames Research Center's Intelligent Mechanisms Group, is a modular operator interface for direct teleoperation and supervisory control of robotic vehicles. Virtual environments enable the efficient display and visualization of complex data. This characteristic allows operators to perceive and control complex systems in a natural fashion, utilizing the highly-evolved human sensory system. VEVI utilizes real-time, interactive, 3D graphics and position / orientation sensors to produce a range of interface modalities from the flat panel (windowed or stereoscopic) screen displays to head mounted/head-tracking stereo displays. The interface provides generic video control capability and has been used to control wheeled, legged, air bearing, and underwater vehicles in a variety of different environments. VEVI was designed and implemented to be modular, distributed and easily operated through long-distance communication links, using a communication paradigm called SYNERGY.

An Infiltration Exercise for Introductory Soil Science

ERIC Educational Resources Information Center

Barbarick, K. A.; Ippolito, J. A.; Butters, G.; Sorge, G. M.

2005-01-01

One of the largest challenges in teaching introductory soil science is explaining the dynamics of soil infiltration. To aid students in understanding the concept and to further engage them in active learning in the soils laboratory course, we developed an exercise using Decagon Mini-Disk Infiltrometers with a tension head (h[subscript o]) of 2 cm.…

The natural weathering of staurolite: crystal-surface textures, relative stability, and the rate-determining step

Treesearch

Michael A. Velbel; Charles L. Basso; Michael J. Zieg

1996-01-01

Mineral surface-textures on naturally weathered crystals of staurolite [monoclinic, pseudo-orthorhombic; Fe4Al18Si8O46(OH)2] indicate that staurolite weathering is generally interface-limited. Etch pits on naturally weathered staurolites are disk-shaped,...

The effect of frictional torque and bending moment on corrosion at the taper interface : an in vitro study.

PubMed

Panagiotidou, A; Meswania, J; Osman, K; Bolland, B; Latham, J; Skinner, J; Haddad, F S; Hart, A; Blunn, G

2015-04-01

The aim of this study was to assess the effect of frictional torque and bending moment on fretting corrosion at the taper interface of a modular femoral component and to investigate whether different combinations of material also had an effect. The combinations we examined were 1) cobalt-chromium (CoCr) heads on CoCr stems 2) CoCr heads on titanium alloy (Ti) stems and 3) ceramic heads on CoCr stems. In test 1 increasing torque was imposed by offsetting the stem in the anteroposterior plane in increments of 0 mm, 4 mm, 6 mm and 8 mm when the torque generated was equivalent to 0 Nm, 9 Nm, 14 Nm and 18 Nm. In test 2 we investigated the effect of increasing the bending moment by offsetting the application of axial load from the midline in the mediolateral plane. Increments of offset equivalent to head + 0 mm, head + 7 mm and head + 14 mm were used. Significantly higher currents and amplitudes were seen with increasing torque for all combinations of material. However, Ti stems showed the highest corrosion currents. Increased bending moments associated with using larger offset heads produced more corrosion: Ti stems generally performed worse than CoCr stems. Using ceramic heads did not prevent corrosion, but reduced it significantly in all loading configurations. ©2015 The British Editorial Society of Bone & Joint Surgery.

Morphogenetic variability of faradiol monoesters in marigold Calendula officinalis L.

PubMed

Zitterl-Eglseer, K; Reznicek, G; Jurenitsch, J; Novak, J; Zitterl, W; Franz, C

2001-01-01

The main compounds of lipophilic extracts of flower heads of marigold (Calendula officinalis L.) are triterpendiol esters, mainly faradiol laurate, faradiol myristate and faradiol palmitate. These faradiol-3-O-monoesters have been quantified for the first time by means of reversed phase HPLC with internal standardisation in different parts of C. officinalis plants, namely ray florets, disk florests, involucral bracts, receptacles, levaes and seeds. The amounts of the esters were highest in ray florets, approximately 10 times lower in disk florets than in the ray florets, and approximately 10 times lower in involucral bracts than in the disk florets. In the leaves only traces of the esters could be detected, and in the receptacles no esters could be detected at all. Quantification in the seed was not possible using this method because of interfering fatty compounds. Concerning the faradiol esters, the dried ray and disk florets only should be preferred as primary products for remedies as demanded in the recently published supplement of the Pharmacopoiea Europaea (1999). Breeding work should focus on varieties with a greater number of ray florets in order to improve the quality of herbal medicinal products derived from marigoid.

[Scanning electron microscopy observation of the growth of osteoblasts on Ti-24Nb-4Zr-8Sn modified by micro-arc oxidation and alkali-heat treatment and implant-bone interface].

PubMed

Han, Xue; Liu, Hong-Chen; Wang, Dong-Sheng; Li, Shu-Jun; Yang, Rui

2011-01-01

To observe the efficacy of micro-arc oxidation and alkali-heat treatment (MAH) on Ti-24Nb-4Zr-8Sn (Ti2448). Disks (diameter of 14.5 mm, thickness of 1 mm) and cylinders (diameter of 3 mm, height of 10 mm) were fabricated from Ti2448 alloy. Samples were divided into three groups: polished (Ti2448), micro-arc oxidation(MAO-Ti2448), micro-arc oxidation and alkali-heat treatment (MAH-Ti2448). MC3T3-E1 osteoblastic cells were cultured on the disks and cell morphology was observed with scanning electron microscopy (SEM) aftre 3 days. The cylinder samples were implanted in the tibia of dogs and implant-bone interface was observed with SEM after 3 months. A rough and porous structure was shown in both MAO and MAH group. The MC3T3-E1 cells on the MAH-Ti2448 discs spread fully in intimate contact with the underlying coarse surface through active cytoskeletal extentions. Osseointegration was formed in the implant-bone interface in MAH samples. MAH treatment can provide a more advantageous Ti2448 surface to osteoblastic cells than MAO treatment does, and the former can improve the implant-bone integration.

Effects of head-slaved navigation and the use of teleports on spatial orientation in virtual environments.

PubMed

Bakker, Niels H; Passenier, Peter O; Werkhoven, Peter J

2003-01-01

The type of navigation interface in a virtual environment (VE)--head slaved or indirect--determines whether or not proprioceptive feedback stimuli are present during movement. In addition, teleports can be used, which do not provide continuous movement but, rather, discontinuously displace the viewpoint over large distances. A two-part experiment was performed. The first part investigated whether head-slaved navigation provides an advantage for spatial learning in a VE. The second part investigated the role of anticipation when using teleports. The results showed that head-slaved navigation has an advantage over indirect navigation for the acquisition of spatial knowledge in a VE. Anticipating the destination of the teleport prevented disorientation after the displacement to a great extent but not completely. The time that was needed for anticipation increased if the teleport involved a rotation of the viewing direction. This research shows the potential added value of using a head-slaved navigation interface--for example, when using VE for training purposes--and provides practical guidelines for the use of teleports in VE applications.

DEVELOPMENT OF A LAMINATED DISK FOR THE SPIN TEK ROTARY MICROFILTER

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

Herman, D.

2011-06-03

Funded by the Department of Energy Office of Environmental Management, EM-31, the Savannah River National Laboratory (SRNL) partnered with SpinTek Filtration{trademark} to develop a filter disk that would withstand a reverse pressure or flow during operation of the rotary microfilter. The ability to withstand a reverse pressure and flow eliminates a potential accident scenario that could have resulted in damage to the filter membranes. While the original welded filter disks have been shown to withstand and reverse pressure/flow in the static condition, the filter disk design discussed in this report will allow a reverse pressure/flow while the disks are rotating.more » In addition, the laminated disk increases the flexibility during filter startup and cleaning operations. The new filter disk developed by SRNL and SpinTek is manufactured with a more open structure significantly reducing internal flow restrictions in the disk. The prototype was tested at the University of Maryland and demonstrated to withstand the reverse pressure due to the centrifugal action of the rotary filter. The tested water flux of the disk was demonstrated to be 1.34 gpm in a single disk test. By comparison, the water flux of the current disk was 0.49 gpm per disk during a 25 disk test. The disk also demonstrated rejection of solids by filtering a 5 wt % Strontium Carbonate slurry with a filtrate clarity of less the 1.4 Nephelometric Turbidity Units (NTU) throughout the two hour test. The Savannah River National Laboratory (SRNL) has been working with SpinTek Filtration{trademark} to adapt the rotary microfilter for radioactive service in the Department of Energy (DOE) Complex. One potential weakness is the loose nature of the membrane on the filter disks. The current disk is constructed by welding the membrane at the outer edge of the disk. The seal for the center of the membrane is accomplished by an o-ring in compression for the assembled stack. The remainder of the membrane is free floating on the disk. This construction requires that a positive pressure be applied to the rotary filter tank to prevent the membrane from rising from the disk structure and potentially contacting the filter turbulence promoter. In addition, one accident scenario is a reverse flow through the filtrate line due to mis-alignment of valves resulting in the membrane rising from the disk structure. The structural integrity of the current disk has been investigated, and shown that the disk can withstand a significant reverse pressure in a static condition. However, the disk will likely incur damage if the filter stack is rotated during a reverse pressure. The development of a laminated disk would have several significant benefits for the operation of the rotary filter including the prevention of a compromise in filter disk integrity during a reverse flow accident, increasing operational flexibility, and increasing the self cleaning ability of the filter. A laminated disk would allow the filter rotor operation prior to a positive pressure in the filter tank. This would prevent the initial dead-head of the filter and prevent the resulting initial filter cake buildup. The laminated disk would allow rotor operation with cleaning fluid, eliminating the need for a recirculation pump. Additionally, a laminated disk would allow a reverse flow of fluid through the membrane pores removing trapped particles.« less

Magnetic bearings for a high-performance optical disk buffer

NASA Technical Reports Server (NTRS)

Hockney, Richard; Hawkey, Timothy

1993-01-01

An optical disk buffer concept can provide gigabit-per-second data rates and terabit capacity through the use of arrays of solid state lasers applied to a stack of erasable/reusable optical disks. The RCA optical disk buffer has evoked interest by NASA for space applications. The porous graphite air bearings in the rotary spindle as well as those used in the linear translation of the read/write head would be replaced by magnetic bearings or mechanical (ball or roller) bearings. Based upon past experience, roller or ball bearings for the translation stages are not feasible. Unsatisfactory, although limited experience exists with ball bearing spindles also. Magnetic bearings, however, appear ideally suited for both applications. The use of magnetic bearings is advantageous in the optical disk buffer because of the absence of physical contact between the rotating and stationary members. This frictionless operation leads to extended life and reduced drag. The manufacturing tolerances that are required to fabricate magnetic bearings would also be relaxed from those required for precision ball and gas bearings. Since magnetic bearings require no lubricant, they are inherently compatible with a space (vacuum) environment. Magnetic bearings also allow the dynamics of the rotor/bearing system to be altered through the use of active control. This provides the potential for reduced vibration, extended regions of stable operation, and more precise control of position.

Uniform Interfaces for Distributed Systems.

DTIC Science & Technology

1980-05-01

in data str ’.ctures on stable storage (such as disk). The Virtual Terminals associated with a particular user (i.e., rM display terminal) are all...vec MESSAGESIZE let error = nil [S ReceiveAny (msg) // The copy is made so that lower-level routines may // munge the message template without losing

Multisensory Public Access Catalogs on CD-ROM.

ERIC Educational Resources Information Center

Harrison, Nancy; Murphy, Brower

1987-01-01

BiblioFile Intelligent Catalog is a CD-ROM-based public access catalog system which incorporates graphics and sound to provide a multisensory interface and artificial intelligence techniques to increase search precision. The system can be updated frequently and inexpensively by linking hard disk drives to CD-ROM optical drives. (MES)

Flexibility and Performance of Parallel File Systems

NASA Technical Reports Server (NTRS)

Kotz, David; Nieuwejaar, Nils

1996-01-01

As we gain experience with parallel file systems, it becomes increasingly clear that a single solution does not suit all applications. For example, it appears to be impossible to find a single appropriate interface, caching policy, file structure, or disk-management strategy. Furthermore, the proliferation of file-system interfaces and abstractions make applications difficult to port. We propose that the traditional functionality of parallel file systems be separated into two components: a fixed core that is standard on all platforms, encapsulating only primitive abstractions and interfaces, and a set of high-level libraries to provide a variety of abstractions and application-programmer interfaces (API's). We present our current and next-generation file systems as examples of this structure. Their features, such as a three-dimensional file structure, strided read and write interfaces, and I/O-node programs, are specifically designed with the flexibility and performance necessary to support a wide range of applications.

RALPH: An online computer program for acquisition and reduction of pulse height data

NASA Technical Reports Server (NTRS)

Davies, R. C.; Clark, R. S.; Keith, J. E.

1973-01-01

A background/foreground data acquisition and analysis system incorporating a high level control language was developed for acquiring both singles and dual parameter coincidence data from scintillation detectors at the Radiation Counting Laboratory at the NASA Manned Spacecraft Center in Houston, Texas. The system supports acquisition of gamma ray spectra in a 256 x 256 coincidence matrix (utilizing disk storage) and simultaneous operation of any of several background support and data analysis functions. In addition to special instruments and interfaces, the hardware consists of a PDP-9 with 24K core memory, 256K words of disk storage, and Dectape and Magtape bulk storage.

Superconductor magnetic reading and writing heads

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

Barnes, F.S.; Dugas, M.P.

1990-11-20

This paper describes a head for interfacing with a magnetic recording media. It comprises: a member of magnetic material forming at least a portion of a magnetic flux circuit ending with a pole face surface in interfacing relation to the media for establishing a main pole in proximity to the media in the magnetic flux circuit, magnetically responsive means in magnetically coupled relation to the magnetic flux circuit, means encasing at least a portion of the external surfaces of the member with superconductive material except for the media interfacing portion of the pole face surface. The encasing means including superconductingmore » material substantially surrounding the magnetic flux circuit in proximity to the pole face surface, and means establishing an environment for the superconductive material at a temperature for maintaining the superconductive material in its superconductive state, whereby magnetic flux in the magnetic flux circuit associated with the encasing means is concentrated within the magnetic flux circuit while placement of the pole face surface in proximity to the recording media permits sensitive magnetic flux controlled information exchanges between the media and the head.« less

Structure and energetics of model amphiphilic molecules at the water liquid-vapor interface - A molecular dynamics study

NASA Technical Reports Server (NTRS)

Pohorille, Andrew; Benjamin, Ilan

1993-01-01

A molecular dynamics study of adsorption of p-n-pentylphenol at infinite dilution at the water liquid-vapor interface is reported. The calculated free energy of adsorption is -8.8 +/- 0.7 kcal/mol, in good agreement with the experimental value of -7.3 kcal/mol. The transition between the interfacial region and the bulk solution is sharp and well-defined by energetic, conformational, and orientational criteria. At the water surface, the phenol head group is mostly immersed in aqueous solvent. The most frequent orientation of the hydrocarbon tail is parallel to the interface, due to dispersion interactions with the water surface. This arrangement of the phenol ring and the alkyl chain requires that the chain exhibits a kink. As the polar head group is being moved into the solvent, the chain length increases and the tail becomes increasingly aligned toward the surface normal, such that the nonpolar part of the molecule exposed to water is minimized. The same effect was achieved when phenol was replaced by a more polar head group, phenolate.

Disk Rock Cutting Tool for the Implementation of Resource-Saving Technologies of Mining of Solid Minerals

NASA Astrophysics Data System (ADS)

Manietyev, Leonid; Khoreshok, Aleksey; Tsekhin, Alexander; Borisov, Andrey

2017-11-01

The directions of a resource and energy saving when creating a boom-type effectors of roadheaders of selective action with disc rock cutting tools on a multi-faceted prisms for the destruction of formation of minerals and rocks pricemax are presented. Justified reversing the modes of the crowns and booms to improve the efficiency of mining works. Parameters of destruction of coal and rock faces by the disk tool of a biconical design with the unified fastening knots to many-sided prisms on effectors of extraction mining machines are determined. Parameters of tension of the interfaced elements of knots of fastening of the disk tool at static interaction with the destroyed face of rocks are set. The technical solutions containing the constructive and kinematic communications realizing counter and reverse mode of rotation of two radial crowns with the disk tool on trihedral prisms and cases of booms with the disk tool on tetrahedral prisms in internal space between two axial crowns with the cutter are proposed. Reserves of expansion of the front of loading outside a table of a feeder of the roadheader of selective action, including side zones in which loading corridors by blades of trihedral prisms in internal space between two radial crowns are created are revealed.

Structural Optimization Methodology for Rotating Disks of Aircraft Engines

NASA Technical Reports Server (NTRS)

Armand, Sasan C.

1995-01-01

In support of the preliminary evaluation of various engine technologies, a methodology has been developed for structurally designing the rotating disks of an aircraft engine. The structural design methodology, along with a previously derived methodology for predicting low-cycle fatigue life, was implemented in a computer program. An interface computer program was also developed that gathers the required data from a flowpath analysis program (WATE) being used at NASA Lewis. The computer program developed for this study requires minimum interaction with the user, thus allowing engineers with varying backgrounds in aeropropulsion to successfully execute it. The stress analysis portion of the methodology and the computer program were verified by employing the finite element analysis method. The 10th- stage, high-pressure-compressor disk of the Energy Efficient Engine Program (E3) engine was used to verify the stress analysis; the differences between the stresses and displacements obtained from the computer program developed for this study and from the finite element analysis were all below 3 percent for the problem solved. The computer program developed for this study was employed to structurally optimize the rotating disks of the E3 high-pressure compressor. The rotating disks designed by the computer program in this study were approximately 26 percent lighter than calculated from the E3 drawings. The methodology is presented herein.

A Robust Camera-Based Interface for Mobile Entertainment

PubMed Central

Roig-Maimó, Maria Francesca; Manresa-Yee, Cristina; Varona, Javier

2016-01-01

Camera-based interfaces in mobile devices are starting to be used in games and apps, but few works have evaluated them in terms of usability or user perception. Due to the changing nature of mobile contexts, this evaluation requires extensive studies to consider the full spectrum of potential users and contexts. However, previous works usually evaluate these interfaces in controlled environments such as laboratory conditions, therefore, the findings cannot be generalized to real users and real contexts. In this work, we present a robust camera-based interface for mobile entertainment. The interface detects and tracks the user’s head by processing the frames provided by the mobile device’s front camera, and its position is then used to interact with the mobile apps. First, we evaluate the interface as a pointing device to study its accuracy, and different factors to configure such as the gain or the device’s orientation, as well as the optimal target size for the interface. Second, we present an in the wild study to evaluate the usage and the user’s perception when playing a game controlled by head motion. Finally, the game is published in an application store to make it available to a large number of potential users and contexts and we register usage data. Results show the feasibility of using this robust camera-based interface for mobile entertainment in different contexts and by different people. PMID:26907288

The Stationary Condensation and Radial Outflow of a Liquid Film on a Horizontal Disk

NASA Technical Reports Server (NTRS)

Bolshinskiy, Leonid; Frenkel, Alexander

2008-01-01

The application of capillary screen liquid acquisition devices to space-based cryogenic propulsion systems is expected to necessitate thermodynamic conditioning in order to stabilize surface tension retention characteristics. The present results have been obtained in the framework of the research of low gravity condensation-flow processes for conditioning cryogenic liquid acquisition devices. The following system is studied: On the top of a subcooled horizontal disk, a liquid film condenses from the ambient saturated vapor. The liquid is forcedly removed at the disk edge, and there is an outward radial flow of the film. Stationary regimes of the flow are uncovered such that (i) the gravity is negligible, being eclipsed by the capillary forces; (ii) the film thickness is everywhere much smaller than the disk radius; and (iii) the slow-flow lubrication approximation is valid. A nonlinear differential equation for the film thickness as a function of the radial coordinate is obtained. The (two-dimensional) fields of velocities, temperature and pressure in the film are explicitly determined by the radial profile of its thickness. The equilibrium is controlled by two parameters: (i) the vapor-disk difference of temperatures and (ii) the liquid exhaust rate. For the flow regimes with a nearly uniform film thickness, the governing equation linearizes, and the film interface is analytically predicted to have a concave-up quartic parabola profile. Thus, perhaps counter-intuitively, the liquid film is thicker at the edge and thinner at the center of the disk.

Adherence of sputtered titanium carbides

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1979-01-01

The study searches for interface treatment that would increase the adhesion of TiC coating to nickel- and titanium-base alloys. Rene 41 (19 wt percent Cr, 11 wt percent Mo, 3 wt percent Ti, balance Ni) and Ti-6Al-4V (6 wt percent Al, 4 wt percent V, balance Ti) are considered. Adhesion of the coatings is evaluated in pin-and disk friction tests. The coatings and interface regions are examined by X-ray photoelectron spectroscopy. Results suggest that sputtered refractory compound coatings adhere best when a mixed compound of coating and substrate metals is formed in the interfacial region. The most effective type of refractory compound interface appears to depend on both substrate and coating material. A combination of metallic interlayer deposition and mixed compound interface formation may be more effective for some substrate coating combinations than either alone.

VizieR Online Data Catalog: FARGO_THORIN 1.0 hydrodynamic code (Chrenko+, 2017)

NASA Astrophysics Data System (ADS)

Chrenko, O.; Broz, M.; Lambrechts, M.

2017-07-01

This archive contains the source files, documentation and example simulation setups of the FARGO_THORIN 1.0 hydrodynamic code. The program was introduced, described and used for simulations in the paper. It is built on top of the FARGO code (Masset, 2000A&AS..141..165M, Baruteau & Masset, 2008ApJ...672.1054B) and it is also interfaced with the REBOUND integrator package (Rein & Liu, 2012A&A...537A.128R). THORIN stands for Two-fluid HydrOdynamics, the Rebound integrator Interface and Non-isothermal gas physics. The program is designed for self-consistent investigations of protoplanetary systems consisting of a gas disk, a disk of small solid particles (pebbles) and embedded protoplanets. Code features: I) Non-isothermal gas disk with implicit numerical solution of the energy equation. The implemented energy source terms are: Compressional heating, viscous heating, stellar irradiation, vertical escape of radiation, radiative diffusion in the midplane and radiative feedback to accretion heating of protoplanets. II) Planets evolved in 3D, with close encounters allowed. The orbits are integrated using the IAS15 integrator (Rein & Spiegel, 2015MNRAS.446.1424R). The code detects the collisions among planets and resolve them as mergers. III) Refined treatment of the planet-disk gravitational interaction. The code uses a vertical averaging of the gravitational potential, as outlined in Muller & Kley (2012A&A...539A..18M). IV) Pebble disk represented by an Eulerian, presureless and inviscid fluid. The pebble dynamics is affected by the Epstein gas drag and optionally by the diffusive effects. We also implemented the drag back-reaction term into the Navier-Stokes equation for the gas. Archive summary: ------------------------------------------------------------------------- directory/file Explanation ------------------------------------------------------------------------- /in_relax Contains setup of the first example simulation /in_wplanet Contains setup of the second example simulation /srcmain Contains the source files of FARGOTHORIN /src_reb Contains the source files of the REBOUND integrator package to be linked with THORIN GUNGPL3 GNU General Public License, version 3 LICENSE License agreement README Simple user's guide UserGuide.pdf Extended user's guide refman.pdf Programer's guide ----------------------------------------------------------------------------- (1 data file).

Cardiopulmonary data acquisition system. Version 2.0, volume 2: Detailed software/hardware documentation

NASA Technical Reports Server (NTRS)

1980-01-01

Detailed software and hardware documentation for the Cardiopulmonary Data Acquisition System is presented. General wiring and timing diagrams are given including those for the LSI-11 computer control panel and interface cables. Flowcharts and complete listings of system programs are provided along with the format of the floppy disk file.

Multichannel Networked Phasemeter Readout and Analysis

NASA Technical Reports Server (NTRS)

Edmonds, Karina

2008-01-01

Netmeter software reads a data stream from up to 250 networked phasemeters, synchronizes the data, saves the reduced data to disk (after applying a low-pass filter), and provides a Web server interface for remote control. Unlike older phasemeter software that requires a special, real-time operating system, this program can run on any general-purpose computer. It needs about five percent of the CPU (central processing unit) to process 20 channels because it adds built-in data logging and network-based GUIs (graphical user interfaces) that are implemented in Scalable Vector Graphics (SVG). Netmeter runs on Linux and Windows. It displays the instantaneous displacements measured by several phasemeters at a user-selectable rate, up to 1 kHz. The program monitors the measure and reference channel frequencies. For ease of use, levels of status in Netmeter are color coded: green for normal operation, yellow for network errors, and red for optical misalignment problems. Netmeter includes user-selectable filters up to 4 k samples, and user-selectable averaging windows (after filtering). Before filtering, the program saves raw data to disk using a burst-write technique.

Transportable telemetry workstation

NASA Technical Reports Server (NTRS)

Collins, Aaron S.

1989-01-01

The goal was to complete the design of a prototype for a Transportable Telemetry Workstation (TTW). The Macintosh 2 is used to provide a low-cost system which can house real-time cards mounted on the NuBus inside the Macintosh 2 plus provide a standardized user interface on the Macintosh 2 console. Prior to a telemetry run, the user will be able to configure his real-time telemetry processing functions from the Macintosh 2 console. During a telemetry run, the real-time cards will store the telemetry data directly on a hard disk while permitting viewing of the data cards on the Macintosh 2 console on various selectable formats. The user will view the cards in terms of the functions they perform and the selectable paths through the cards, it is not required to become involved directly in hardware issue except in terms of the functional configuration of the system components. The TTW will accept telemetry data from an RS422 serial input data bus, pass it through a frame synchronizer card and on to a real time controller card via a telemetry backplane bus. The controller card will then route the data to a hard disk through a SCSI interface, and/or to a user interface on the Macintosh 2 console by way of the Macintosh 2 NuBus. The three major components to be designed, therefore, are the TTW Controller Card, the TTW Synchronizer Card, and the NuBus/Macintosh 2 User Interface. Design and prototyping of this state-of-the-art, transportable, low-cost, easy-to-use multiprocessor telemetry system is continuing. Other functions are planned for the future.

Transportable telemetry workstation

NASA Astrophysics Data System (ADS)

Collins, Aaron S.

1989-09-01

The goal was to complete the design of a prototype for a Transportable Telemetry Workstation (TTW). The Macintosh 2 is used to provide a low-cost system which can house real-time cards mounted on the NuBus inside the Macintosh 2 plus provide a standardized user interface on the Macintosh 2 console. Prior to a telemetry run, the user will be able to configure his real-time telemetry processing functions from the Macintosh 2 console. During a telemetry run, the real-time cards will store the telemetry data directly on a hard disk while permitting viewing of the data cards on the Macintosh 2 console on various selectable formats. The user will view the cards in terms of the functions they perform and the selectable paths through the cards, it is not required to become involved directly in hardware issue except in terms of the functional configuration of the system components. The TTW will accept telemetry data from an RS422 serial input data bus, pass it through a frame synchronizer card and on to a real time controller card via a telemetry backplane bus. The controller card will then route the data to a hard disk through a SCSI interface, and/or to a user interface on the Macintosh 2 console by way of the Macintosh 2 NuBus. The three major components to be designed, therefore, are the TTW Controller Card, the TTW Synchronizer Card, and the NuBus/Macintosh 2 User Interface. Design and prototyping of this state-of-the-art, transportable, low-cost, easy-to-use multiprocessor telemetry system is continuing. Other functions are planned for the future.

Contact sheet recording with a self-acting negative air bearing

NASA Technical Reports Server (NTRS)

Muftu , Sinan (Inventor); Hinteregger, Hans F (Inventor)

2000-01-01

A flat head and a tape transport arrangement impart a wrap angle to the tape at the upstream corner of the head. The wrap angle, corner sharpness and tape stiffness are sufficient to cause a moving tape to form a hollow bump at the upstream corner, thereby creating a hollow into which entrained air can expand, causing a subambient pressure within and downstream of the bump. This pressure keeps the tape in contact with the head. It is created without the need for a groove or complex pressure relief slot(s). No contact pressure arises at the signal exchange site due to media wrap. The highest contact pressures are developed at a wrapped upstream corner. For a tape drive, traveling in both forward and reverse, the wrap can be at both the upstream and downstream (which is the reverse upstream) corners. Heads that are not flat can also be used, if the wrap angle relative to a main surface is sufficient and not too large. The wrapped head can also be used with rotating media, such as disks (floppy and hard) and rotating heads, such as helical wound heads for video recording. Multiple flat tape bearing surfaces can be separated by grooves and/or angles. Each flat can carry heads along one or more gap lines. Multiple adjacent narrow tracks can thus be written for extreme high track density recording.

Topology changes in a water-oil swirling flow

NASA Astrophysics Data System (ADS)

Carrión, Luis; Herrada, Miguel A.; Shtern, Vladimir N.

2017-03-01

This paper reveals the flow topology hidden in the experimental study by Fujimoto and Takeda ["Topology changes of the interface between two immiscible liquid layers by a rotating lid," Phys. Rev. E 80, 015304(R) (2009)]. Water and silicone oil fill a sealed vertical cylindrical container. The rotating top disk induces the meridional circulation and swirl of both fluids. As the rotation strength Reo increases, the interface takes shapes named, by the authors, hump, cusp, Mt. Fuji, and bell. Our numerical study reproduces the interface geometry and discloses complicated flow patterns. For example at Reo = 752, where the interface has the "Mt. Fuji" shape, the water motion has three bulk cells and the oil motion has two bulk cells. This topology helps explain the interface geometry. In addition, our study finds that the steady axisymmetric flow suffers from the shear-layer instability for Reo > 324, i.e., before the interface becomes remarkably deformed. The disturbance energy is concentrated in the water depth. This explains why the instability does not significantly affect the interface shape in the experiment.

Transient thermal stresses in a reinforced hollow disk or cylinder containing a radial crack

NASA Technical Reports Server (NTRS)

Tang, R.; Erdogan, F.

1983-01-01

The transient thermal stress problem in a hollow cylinder or a disk containing a radial crack is considered. It is assumed that the cylinder is reinforced on its inner boundary by a membrane which has thermoelastic constants different than those of the base material. The transient temperature, thermal stresses and the crack tip stress intensity factors are calculated in a cylinder which is subjected to a sudden change of temperature on the inside surface. The results are obtained for various dimensionless parameters and material constants. The special cases of the crack terminating at the cylinder-membrane interface and of the broken membrane are separately considered and some examples are given.

Transient thermal stresses in a reinforced hollow disk or cylinder containing a radial crack

NASA Technical Reports Server (NTRS)

Tang, R.; Erdogan, F.

1984-01-01

The transient thermal stress problem in a hollow cylinder or a disk containing a radial crack is considered. It is assumed that the cylinder is reinforced on its inner boundary by a membrane which has thermoelastic constants different than those of the base material. The transient temperature, thermal stresses and the crack tip stress intensity factors are calculated in a cylinder which is subjected to a sudden change of temperature on the inside surface. The results are obtained for various dimensionless parameters and material constants. The special cases of the crack terminating at the cylinder-membrane interface and of the broken membrane are separately considered and some examples are given.

Ultrastructural and biochemical localization of N-RAP at the interface between myofibrils and intercalated disks in the mouse heart.

PubMed

Zhang, J Q; Elzey, B; Williams, G; Lu, S; Law, D J; Horowits, R

2001-12-11

N-RAP is a recently discovered muscle-specific protein found at cardiac intercalated disks. Double immunogold labeling of mouse cardiac muscle reveals that vinculin is located immediately adjacent to the fascia adherens region of the intercalated disk membrane, while N-RAP extends approximately 100 nm further toward the interior of the cell. We partially purified cardiac intercalated disks using low- and high-salt extractions followed by density gradient centrifugation. Immunoblots show that this preparation is highly enriched in desmin and junctional proteins, including N-RAP, talin, vinculin, beta1-integrin, N-cadherin, and connexin 43. Electron microscopy and immunolabeling demonstrate that N-RAP and vinculin are associated with the large fragments of intercalated disks that are present in this preparation, which also contains numerous membrane vesicles. Detergent treatment of the partially purified intercalated disks removed the membrane vesicles and extracted vinculin and beta1-integrin. Further separation on a sucrose gradient removed residual actin and myosin and yielded a fraction morphologically similar to fasciae adherentes that was highly enriched in N-RAP, N-cadherin, connexin 43, talin, desmin, and alpha-actinin. The finding that N-RAP copurifies with detergent-extracted intercalated disk fragments even though beta-integrin and vinculin have been completely removed suggests that N-RAP association with the adherens junction region is mediated by the cadherin system. Consistent with this hypothesis, we found that recombinant N-RAP fragments bind alpha-actinin in a gel overlay assay. In addition, immunofluorescence shows that N-RAP remains bound at the ends of isolated, detergent-treated cardiac myofibrils. These results demonstrate that N-RAP remains tightly bound to myofibrils and fasciae adherentes during biochemical purification and may be a key constituent in the mechanical link between these two structures.

ZFS on RBODs - Leveraging RAID Controllers for Metrics and Enclosure Management

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

Stearman, D. M.

2015-03-30

Traditionally, the Lustre file system has relied on the ldiskfs file system with reliable RAID (Redundant Array of Independent Disks) storage underneath. As of Lustre 2.4, ZFS was added as a backend file system, with built-in software RAID, thereby removing the need of expensive RAID controllers. ZFS was designed to work with JBOD (Just a Bunch Of Disks) storage enclosures under the Solaris Operating System, which provided a rich device management system. Long time users of the Lustre file system have relied on the RAID controllers to provide metrics and enclosure monitoring and management services, with rich APIs and commandmore » line interfaces. This paper will study a hybrid approach using an advanced full featured RAID enclosure which is presented to the host as a JBOD, This RBOD (RAIDed Bunch Of Disks) allows ZFS to do the RAID protection and error correction, while the RAID controller handles management of the disks and monitors the enclosure. It was hoped that the value of the RAID controller features would offset the additional cost, and that performance would not suffer in this mode. The test results revealed that the hybrid RBOD approach did suffer reduced performance.« less

High-Speed Recording of Test Data on Hard Disks

NASA Technical Reports Server (NTRS)

Lagarde, Paul M., Jr.; Newnan, Bruce

2003-01-01

Disk Recording System (DRS) is a systems-integration computer program for a direct-to-disk (DTD) high-speed data acquisition system (HDAS) that records rocket-engine test data. The HDAS consists partly of equipment originally designed for recording the data on tapes. The tape recorders were replaced with hard-disk drives, necessitating the development of DRS to provide an operating environment that ties two computers, a set of five DTD recorders, and signal-processing circuits from the original tape-recording version of the HDAS into one working system. DRS includes three subsystems: (1) one that generates a graphical user interface (GUI), on one of the computers, that serves as a main control panel; (2) one that generates a GUI, on the other computer, that serves as a remote control panel; and (3) a data-processing subsystem that performs tasks on the DTD recorders according to instructions sent from the main control panel. The software affords capabilities for dynamic configuration to record single or multiple channels from a remote source, remote starting and stopping of the recorders, indexing to prevent overwriting of data, and production of filtered frequency data from an original time-series data file.

Mapping of medical acronyms and initialisms to Medical Subject Headings (MeSH) across selected systems

PubMed Central

Shultz, Mary

2006-01-01

Introduction: Given the common use of acronyms and initialisms in the health sciences, searchers may be entering these abbreviated terms rather than full phrases when searching online systems. The purpose of this study is to evaluate how various MEDLINE Medical Subject Headings (MeSH) interfaces map acronyms and initialisms to the MeSH vocabulary. Methods: The interfaces used in this study were: the PubMed MeSH database, the PubMed Automatic Term Mapping feature, the NLM Gateway Term Finder, and Ovid MEDLINE. Acronyms and initialisms were randomly selected from 2 print sources. The test data set included 415 randomly selected acronyms and initialisms whose related meanings were found to be MeSH terms. Each acronym and initialism was entered into each MEDLINE MeSH interface to determine if it mapped to the corresponding MeSH term. Separately, 46 commonly used acronyms and initialisms were tested. Results: While performance differed widely, the success rates were low across all interfaces for the randomly selected terms. The common acronyms and initialisms tested at higher success rates across the interfaces, but the differences between the interfaces remained. Conclusion: Online interfaces do not always map medical acronyms and initialisms to their corresponding MeSH phrases. This may lead to inaccurate results and missed information if acronyms and initialisms are used in search strategies. PMID:17082832

ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS

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

Belyaev, Mikhail A.; Rafikov, Roman R.; Stone, James M., E-mail: rrr@astro.princeton.edu

The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification ofmore » three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with the conventional notion of local transport by turbulent stresses. Our results have important implications for semianalytical models that describe the spectral emission from boundary layers.« less

An automatic eye detection and tracking technique for stereo video sequences

NASA Astrophysics Data System (ADS)

Paduru, Anirudh; Charalampidis, Dimitrios; Fouts, Brandon; Jovanovich, Kim

2009-05-01

Human-computer interfacing (HCI) describes a system or process with which two information processors, namely a human and a computer, attempt to exchange information. Computer-to-human (CtH) information transfer has been relatively effective through visual displays and sound devices. On the other hand, the human-tocomputer (HtC) interfacing avenue has yet to reach its full potential. For instance, the most common HtC communication means are the keyboard and mouse, which are already becoming a bottleneck in the effective transfer of information. The solution to the problem is the development of algorithms that allow the computer to understand human intentions based on their facial expressions, head motion patterns, and speech. In this work, we are investigating the feasibility of a stereo system to effectively determine the head position, including the head rotation angles, based on the detection of eye pupils.

A neural-based remote eye gaze tracker under natural head motion.

PubMed

Torricelli, Diego; Conforto, Silvia; Schmid, Maurizio; D'Alessio, Tommaso

2008-10-01

A novel approach to view-based eye gaze tracking for human computer interface (HCI) is presented. The proposed method combines different techniques to address the problems of head motion, illumination and usability in the framework of low cost applications. Feature detection and tracking algorithms have been designed to obtain an automatic setup and strengthen the robustness to light conditions. An extensive analysis of neural solutions has been performed to deal with the non-linearity associated with gaze mapping under free-head conditions. No specific hardware, such as infrared illumination or high-resolution cameras, is needed, rather a simple commercial webcam working in visible light spectrum suffices. The system is able to classify the gaze direction of the user over a 15-zone graphical interface, with a success rate of 95% and a global accuracy of around 2 degrees , comparable with the vast majority of existing remote gaze trackers.

Perception and Haptic Rendering of Friction Moments.

PubMed

Kawasaki, H; Ohtuka, Y; Koide, S; Mouri, T

2011-01-01

This paper considers moments due to friction forces on the human fingertip. A computational technique called the friction moment arc method is presented. The method computes the static and/or dynamic friction moment independent of a friction force calculation. In addition, a new finger holder to display friction moment is presented. This device incorporates a small brushless motor and disk, and connects the human's finger to an interface finger of the five-fingered haptic interface robot HIRO II. Subjects' perception of friction moment while wearing the finger holder, as well as perceptions during object manipulation in a virtual reality environment, were evaluated experimentally.

Method and Apparatus for Assessment of Changes in Intracranial Pressure

NASA Technical Reports Server (NTRS)

Yost, William T. (Inventor); Cantrell, John H. (Inventor)

2002-01-01

A non-invasive method and apparatus for monitoring changes in intracranial pressure which removes extracranial effects from the measurements. The method and apparatus can include the supplying of a fixed frequency electrical output to a transducer coupled to the patient's head, thereby generating an acoustical tone burst in the patient's head which generates a first echo and a second echo, the first echo reflecting from a first interface in the side of the patient's head coupled to the transducer, and the second echo reflecting from a second interface at the opposite side of the patient's head. The first and second echoes are received by the transducer which can generate a first electrical signal and a second electrical signal, wherein the first and second electrical signals vary in accordance with the corresponding first and second echoes. The counterbalancing phase shifts required to bring about quadrature between each of the first and second electrical signals and the fixed frequency electrical output can be measured, and values for the change in intracranial distance based on the changes in the counterbalancing phase shifts can be obtained.

Intelligent holographic databases

NASA Astrophysics Data System (ADS)

Barbastathis, George

Memory is a key component of intelligence. In the human brain, physical structure and functionality jointly provide diverse memory modalities at multiple time scales. How could we engineer artificial memories with similar faculties? In this thesis, we attack both hardware and algorithmic aspects of this problem. A good part is devoted to holographic memory architectures, because they meet high capacity and parallelism requirements. We develop and fully characterize shift multiplexing, a novel storage method that simplifies disk head design for holographic disks. We develop and optimize the design of compact refreshable holographic random access memories, showing several ways that 1 Tbit can be stored holographically in volume less than 1 m3, with surface density more than 20 times higher than conventional silicon DRAM integrated circuits. To address the issue of photorefractive volatility, we further develop the two-lambda (dual wavelength) method for shift multiplexing, and combine electrical fixing with angle multiplexing to demonstrate 1,000 multiplexed fixed holograms. Finally, we propose a noise model and an information theoretic metric to optimize the imaging system of a holographic memory, in terms of storage density and error rate. Motivated by the problem of interfacing sensors and memories to a complex system with limited computational resources, we construct a computer game of Desert Survival, built as a high-dimensional non-stationary virtual environment in a competitive setting. The efficacy of episodic learning, implemented as a reinforced Nearest Neighbor scheme, and the probability of winning against a control opponent improve significantly by concentrating the algorithmic effort to the virtual desert neighborhood that emerges as most significant at any time. The generalized computational model combines the autonomous neural network and von Neumann paradigms through a compact, dynamic central representation, which contains the most salient features of the sensory inputs, fused with relevant recollections, reminiscent of the hypothesized cognitive function of awareness. The Declarative Memory is searched both by content and address, suggesting a holographic implementation. The proposed computer architecture may lead to a novel paradigm that solves 'hard' cognitive problems at low cost.

The accretion and spreading of matter on white dwarfs

NASA Astrophysics Data System (ADS)

Fisker, Jacob Lund; Balsara, Dinshaw S.; Burger, Tom

2006-10-01

For a slowly rotating non-magnetized white dwarf the accretion disk extends all the way to the star. At the interface between the accretion disk and the star, the matter moves through a boundary layer (BL) and then spreads toward the poles as new matter continuously piles up behind it. We have solved the 3d compressible Navier-Stokes equations on an axisymmetric grid to determine the structure of this BL for different accretion rates (states). The high states show a spreading BL which sets off a gravity wave in the surface matter. The accretion flow moves supersonically over the cusp making it susceptible to the rapid development of gravity wave and/or Kelvin-Helmholtz instabilities. This BL is optically thick and extends more than 30° to either side of the disk plane after 3/4 of a Keplerian rotation period (tK = 19 s). The low states also show a spreading BL, but here the accretion flow does not set off gravity waves and it is optically thin.

Tribological Properties of Ti-Based Alloys in a Simulated Bone-Implant Interface with Ringer's Solution at Fretting Contacts

PubMed Central

Ramos-Saenz, C.R.; Sundaram, P.A.; Diffoot-Carlo, N.

2010-01-01

The wear properties of oxidized and non-oxidized gamma-TiAl (a potential biomaterial) as well as Ti-6Al-4V and CP-Ti disks were studied and characterized by means of standard wear tests using a custom made bone pin arrangement. The Ti-base disks were oxidized in air at 500°C and 800°C for one hour. The tribological properties of the oxides formed over the disks were studied using a linear reciprocating wear testing machine under both dry and simulated biological conditions using Ringer's solution. Loss of metal oxide and coefficient of friction values were determined from the wear testing. From the results, abrasion and adhesion were the primary wear mechanisms in each of the three alloy-bone pairs. Specifically, the oxide formed on gamma-TiAl possessed the highest COF and wear resistance of the three materials which were studied. Also, as expected, bone wears down faster than the Ti-base metal oxide. PMID:20826360

Study on the Correlation Between Dynamical Behavior and Friction/Wear Mechanism Under the Effect of Grooves

NASA Astrophysics Data System (ADS)

Zhu, Z. Y.; Mo, J. L.; Wang, D. W.; Zhao, J.; Zhu, M. H.; Zhou, Z. R.

2018-04-01

In this work, the interfacial friction and wear and vibration characteristics are studied by sliding a chromium bearing steel ball (AISI 52100) over both multi-grooved and single-grooved forged steel disks (20CrMnMo) at low and high rotating speeds in order to reveal the effect mechanism of groove-textured surface on tribological behaviors. The results show that the grooves modify the contact state of the ball and the disk at the contact interface. This consequently causes variations in the normal displacement, normal force, and friction force signals. The changes in these three signals become more pronounced with increasing groove width at a low speed. The collision behavior between the ball and the groove increase the amplitude of vibration acceleration at a high speed. The test results suggest that grooves with appropriate widths could trap wear debris on the ball surface while avoiding a strong collision between the disk and the ball, resulting in an improvement in the wear states.

Fatigue failure of dentin-composite disks subjected to cyclic diametral compression

PubMed Central

Li, Yuping; Carrera, Carola; Chen, Ruoqiong; Li, Jianying; Chen, Yungchung; Lenton, Patricia; Rudney, Joel. D.; Jones, Robert S.; Aparicio, Conrado; Fok, Alex

2015-01-01

Objective Our aim was to establish the relationship between cyclic loading and fatigue life of the dentin-composite interface using the newly developed disk in diametral compression tests. The results were then used to estimate the fatigue life of restored teeth under occlusal loading. Methods Disk specimens (5mm dia. × 2mm thick) were prepared using bovine incisors and restored with either a methacrylate-based composite Z100™ with Adper Single Bond Plus (Z100) or silorane-based composite Filtek ™ LS with LS System adhesive (LS). The dentin-composite disks were tested under cyclic diametral compression to determine the number of cycles to failure (Nf) at three load levels (n = 3 per group). Finite element analysis (FEA) was used to calculate the interfacial stresses (σ) within the specimen, to establish the σ vs. Nf curves, and those within a restored tooth under normal chewing forces (15N maximum). These were then used to estimate the lifetime of the restored tooth for the two restorative systems. Results The disks restored with LS had a higher fatigue resistance than those restored with Z100. The maximum interfacial stress in the restored tooth determined by FEA was ∼0.5MPa. Based on the estimate of 300,000 cycles of chewing per year, the predicted lifetime under occlusal loading for teeth restored with LS and Z100 was 33 and 10 years, respectively. Significance The disk in cyclic diametral compression has been used successfully to provide fatigue data which allows the lifetime of composite-restored teeth under occlusal loading to be predicted using numerical simulation. PMID:25958269

Interplay between the spin transfer and spin orbit torques on domain walls at the 5d/3d-alloy interfaces

NASA Astrophysics Data System (ADS)

Kalitsov, Alan; Okatov, Sergey; Zarzhitsky, Pavel; Chshiev, Mairbek; Velev, Julian; Butler, William; Mryasov, Oleg

2014-03-01

The manipulations of domain wall (DW) in thin ferromagnetic layers by current and the spin-orbit coupling (SOC) have attracted significant interest. We report two band model calculations of the spin torque (ST) and the spin current (SC) at 5d/3d interfaces with head-to-head, Bloch and Neel DWs. These calculations are based on the non-equilibrium Green Function formalism and the tight binding Hamiltonian including the s-d exchange interactions and the Rashba SOC parameterized on the basis of ab-initio calculations for Fe/W, FeCo/Ta and Co/Pt interfaces. We find that SOC significantly modifies the ST and violates relations between the spin transfer torque and the divergence of the spin current. This work was supported in part by a Semiconductor Research Corporation program, sponsored by MARCO and DARPA.

A finite element head and neck model as a supportive tool for deformable image registration.

PubMed

Kim, Jihun; Saitou, Kazuhiro; Matuszak, Martha M; Balter, James M

2016-07-01

A finite element (FE) head and neck model was developed as a tool to aid investigations and development of deformable image registration and patient modeling in radiation oncology. Useful aspects of a FE model for these purposes include ability to produce realistic deformations (similar to those seen in patients over the course of treatment) and a rational means of generating new configurations, e.g., via the application of force and/or displacement boundary conditions. The model was constructed based on a cone-beam computed tomography image of a head and neck cancer patient. The three-node triangular surface meshes created for the bony elements (skull, mandible, and cervical spine) and joint elements were integrated into a skeletal system and combined with the exterior surface. Nodes were additionally created inside the surface structures which were composed of the three-node triangular surface meshes, so that four-node tetrahedral FE elements were created over the whole region of the model. The bony elements were modeled as a homogeneous linear elastic material connected by intervertebral disks. The surrounding tissues were modeled as a homogeneous linear elastic material. Under force or displacement boundary conditions, FE analysis on the model calculates approximate solutions of the displacement vector field. A FE head and neck model was constructed that skull, mandible, and cervical vertebrae were mechanically connected by disks. The developed FE model is capable of generating realistic deformations that are strain-free for the bony elements and of creating new configurations of the skeletal system with the surrounding tissues reasonably deformed. The FE model can generate realistic deformations for skeletal elements. In addition, the model provides a way of evaluating the accuracy of image alignment methods by producing a ground truth deformation and correspondingly simulated images. The ability to combine force and displacement conditions provides flexibility for simulating realistic anatomic configurations.

Head Pose Estimation on Eyeglasses Using Line Detection and Classification Approach

NASA Astrophysics Data System (ADS)

Setthawong, Pisal; Vannija, Vajirasak

This paper proposes a unique approach for head pose estimation of subjects with eyeglasses by using a combination of line detection and classification approaches. Head pose estimation is considered as an important non-verbal form of communication and could also be used in the area of Human-Computer Interface. A major improvement of the proposed approach is that it allows estimation of head poses at a high yaw/pitch angle when compared with existing geometric approaches, does not require expensive data preparation and training, and is generally fast when compared with other approaches.

Comparison of three different techniques for camera and motion control of a teleoperated robot.

PubMed

Doisy, Guillaume; Ronen, Adi; Edan, Yael

2017-01-01

This research aims to evaluate new methods for robot motion control and camera orientation control through the operator's head orientation in robot teleoperation tasks. Specifically, the use of head-tracking in a non-invasive way, without immersive virtual reality devices was combined and compared with classical control modes for robot movements and camera control. Three control conditions were tested: 1) a condition with classical joystick control of both the movements of the robot and the robot camera, 2) a condition where the robot movements were controlled by a joystick and the robot camera was controlled by the user head orientation, and 3) a condition where the movements of the robot were controlled by hand gestures and the robot camera was controlled by the user head orientation. Performance, workload metrics and their evolution as the participants gained experience with the system were evaluated in a series of experiments: for each participant, the metrics were recorded during four successive similar trials. Results shows that the concept of robot camera control by user head orientation has the potential of improving the intuitiveness of robot teleoperation interfaces, specifically for novice users. However, more development is needed to reach a margin of progression comparable to a classical joystick interface. Copyright © 2016 Elsevier Ltd. All rights reserved.

Identifying arbitrary parameter zonation using multiple level set functions

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

Lu, Zhiming; Vesselinov, Velimir Valentinov; Lei, Hongzhuan

In this paper, we extended the analytical level set method [1, 2] for identifying a piece-wisely heterogeneous (zonation) binary system to the case with an arbitrary number of materials with unknown material properties. In the developed level set approach, starting from an initial guess, the material interfaces are propagated through iterations such that the residuals between the simulated and observed state variables (hydraulic head) is minimized. We derived an expression for the propagation velocity of the interface between any two materials, which is related to the permeability contrast between the materials on two sides of the interface, the sensitivity ofmore » the head to permeability, and the head residual. We also formulated an expression for updating the permeability of all materials, which is consistent with the steepest descent of the objective function. The developed approach has been demonstrated through many examples, ranging from totally synthetic cases to a case where the flow conditions are representative of a groundwater contaminant site at the Los Alamos National Laboratory. These examples indicate that the level set method can successfully identify zonation structures, even if the number of materials in the model domain is not exactly known in advance. Although the evolution of the material zonation depends on the initial guess field, inverse modeling runs starting with different initial guesses fields may converge to the similar final zonation structure. These examples also suggest that identifying interfaces of spatially distributed heterogeneities is more important than estimating their permeability values.« less

Analytical solution for the transient response of a fluid/saturated porous medium halfspace system subjected to an impulsive line source

NASA Astrophysics Data System (ADS)

Shan, Zhendong; Ling, Daosheng; Jing, Liping; Li, Yongqiang

2018-05-01

In this paper, transient wave propagation is investigated within a fluid/saturated porous medium halfspace system with a planar interface that is subjected to a cylindrical P-wave line source. Assuming the permeability coefficient is sufficiently large, analytical solutions for the transient response of the fluid/saturated porous medium halfspace system are developed. Moreover, the analytical solutions are presented in simple closed forms wherein each term represents a transient physical wave, especially the expressions for head waves. The methodology utilised to determine where the head wave can emerge within the system is also given. The wave fields within the fluid and porous medium are first defined considering the behaviour of two compressional waves and one tangential wave in the saturated porous medium and one compressional wave in the fluid. Substituting these wave fields into the interface continuity conditions, the analytical solutions in the Laplace domain are then derived. To transform the solutions into the time domain, a suitable distortion of the contour is provided to change the integration path of the solution, after which the analytical solutions in the Laplace domain are transformed into the time domain by employing Cagniard's method. Numerical examples are provided to illustrate some interesting features of the fluid/saturated porous medium halfspace system. In particular, the interface wave and head waves that propagate along the interface between the fluid and saturated porous medium can be observed.

Identifying arbitrary parameter zonation using multiple level set functions

DOE PAGES

Lu, Zhiming; Vesselinov, Velimir Valentinov; Lei, Hongzhuan

2018-03-14

In this paper, we extended the analytical level set method [1, 2] for identifying a piece-wisely heterogeneous (zonation) binary system to the case with an arbitrary number of materials with unknown material properties. In the developed level set approach, starting from an initial guess, the material interfaces are propagated through iterations such that the residuals between the simulated and observed state variables (hydraulic head) is minimized. We derived an expression for the propagation velocity of the interface between any two materials, which is related to the permeability contrast between the materials on two sides of the interface, the sensitivity ofmore » the head to permeability, and the head residual. We also formulated an expression for updating the permeability of all materials, which is consistent with the steepest descent of the objective function. The developed approach has been demonstrated through many examples, ranging from totally synthetic cases to a case where the flow conditions are representative of a groundwater contaminant site at the Los Alamos National Laboratory. These examples indicate that the level set method can successfully identify zonation structures, even if the number of materials in the model domain is not exactly known in advance. Although the evolution of the material zonation depends on the initial guess field, inverse modeling runs starting with different initial guesses fields may converge to the similar final zonation structure. These examples also suggest that identifying interfaces of spatially distributed heterogeneities is more important than estimating their permeability values.« less

Identifying arbitrary parameter zonation using multiple level set functions

NASA Astrophysics Data System (ADS)

Lu, Zhiming; Vesselinov, Velimir V.; Lei, Hongzhuan

2018-07-01

In this paper, we extended the analytical level set method [1,2] for identifying a piece-wisely heterogeneous (zonation) binary system to the case with an arbitrary number of materials with unknown material properties. In the developed level set approach, starting from an initial guess, the material interfaces are propagated through iterations such that the residuals between the simulated and observed state variables (hydraulic head) is minimized. We derived an expression for the propagation velocity of the interface between any two materials, which is related to the permeability contrast between the materials on two sides of the interface, the sensitivity of the head to permeability, and the head residual. We also formulated an expression for updating the permeability of all materials, which is consistent with the steepest descent of the objective function. The developed approach has been demonstrated through many examples, ranging from totally synthetic cases to a case where the flow conditions are representative of a groundwater contaminant site at the Los Alamos National Laboratory. These examples indicate that the level set method can successfully identify zonation structures, even if the number of materials in the model domain is not exactly known in advance. Although the evolution of the material zonation depends on the initial guess field, inverse modeling runs starting with different initial guesses fields may converge to the similar final zonation structure. These examples also suggest that identifying interfaces of spatially distributed heterogeneities is more important than estimating their permeability values.

Skills based evaluation of alternative input methods to command a semi-autonomous electric wheelchair.

PubMed

Rojas, Mario; Ponce, Pedro; Molina, Arturo

2016-08-01

This paper presents the evaluation, under standardized metrics, of alternative input methods to steer and maneuver a semi-autonomous electric wheelchair. The Human-Machine Interface (HMI), which includes a virtual joystick, head movements and speech recognition controls, was designed to facilitate mobility skills for severely disabled people. Thirteen tasks, which are common to all the wheelchair users, were attempted five times by controlling it with the virtual joystick and the hands-free interfaces in different areas for disabled and non-disabled people. Even though the prototype has an intelligent navigation control, based on fuzzy logic and ultrasonic sensors, the evaluation was done without assistance. The scored values showed that both controls, the head movements and the virtual joystick have similar capabilities, 92.3% and 100%, respectively. However, the 54.6% capacity score obtained for the speech control interface indicates the needs of the navigation assistance to accomplish some of the goals. Furthermore, the evaluation time indicates those skills which require more user's training with the interface and specifications to improve the total performance of the wheelchair.

Dosimetric measurement of scattered radiation from dental implants in simulated head and neck radiotherapy.

PubMed

Wang, R; Pillai, K; Jones, P K

1998-01-01

The purpose of this study was to examine the dose enhancement at bone-implant interfaces from scattered radiation during simulated head and neck radiotherapy. Three cylindric implant systems with different compositions (pure titanium, titanium-aluminum-vanadium alloy, titanium coated with hydroxyapatite) and a high gold content transmandibular implant system (gold-copper-silver alloy) were studied. Extruded lithium fluoride single crystal chips were used as thermoluminescent material to measure radiation dose enhancement at 0, 1, and 2 mm from the bone-implant interface. The relative doses in buccal, lingual, mesial, and distal directions were also recorded and compared. The results indicated that the highest dose enhancement occurred at a distance of 0 mm from the bone-implant interface for all the implant systems studied. The transmandibular implants had higher scattered radiation than other groups at 0 mm and at 1 mm from the bone-implant interface. There was no significant difference of dose enhancement between buccal, lingual, mesial, and distal directions. Titanium implants coated with hydroxyapatite demonstrated the best results under the simulated irradiation.

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

Wicks, Christopher Donald; Madin, Mark Michael

A cam carrier assembly includes a cylinder head having valves and a camshaft having lobes. A cam carrier has a first side coupled with the cylinder head engaging around the valves and a second side with bearing surfaces supporting the camshaft. A series of apertures extend between the first and second sides for the lobes to interface with the valves. The cam carrier is made of carbon fiber composite insulating the camshaft from the cylinder head and providing substantial weight reduction to an upper section of an associated engine.

A Head in Virtual Reality: Development of A Dynamic Head and Neck Model

ERIC Educational Resources Information Center

Nguyen, Ngan; Wilson, Timothy D.

2009-01-01

Advances in computer and interface technologies have made it possible to create three-dimensional (3D) computerized models of anatomical structures for visualization, manipulation, and interaction in a virtual 3D environment. In the past few decades, a multitude of digital models have been developed to facilitate complex spatial learning of the…

Association between temporomandibular disorders and abnormal head postures.

PubMed

Faulin, Evandro Francisco; Guedes, Carlos Gramani; Feltrin, Pedro Paulo; Joffiley, Cláudia Maria Mithie Suda Costa

2015-01-01

This study examines the possible correlation between the prevalence of temporomandibular disorders (TMD) and different head postures in the frontal and sagittal planes using photographs of undergraduate students in the School of Dentistry at the Universidade de Brasília - UnB, Brazil. In this nonrandomized, cross-sectional study, the diagnoses of TMD were made with the Research Diagnostic Criteria (RDC)/TMD axis I. The craniovertebral angle was used to evaluate forward head posture in the sagittal plane, and the interpupillary line was used to measure head tilt in the frontal plane. The measurements to evaluate head posture were made using the Software for the Assessment of Posture (SAPO). Students were divided into two study groups, based on the presence or absence of TMD. The study group comprised 46 students and the control group comprised 80 students. Data about head posture and TMD were analyzed with the Statistical Package for the Social Sciences, version 13. Most cases of TMD were classified as degenerative processes (group III), followed by disk displacement (group II) and muscle disorders (group I). There was no sex predominance for the type of disorder. No association was found between prevalence rates for head postures in the frontal plane and the occurrence of TMD. The same result was found for the association of TMD diagnosis with craniovertebral angle among men and women, and the group that contained both men and women. Abnormal head postures were common among individuals both with and without TMD. No association was found between head posture evaluated in the frontal and sagittal planes and TMD diagnosis with the use of RDC/TMD.

The Plunge Phase of Friction Stir Welding

NASA Technical Reports Server (NTRS)

Nunes, Arthur; McClure, John; Avila, Ricardo

2005-01-01

Torque and plunge force during the initial plunge phase in Friction Stir Welding were measured for a 0.5 inch diameter pin entering a 2219 aluminum alloy plate. Weld structures were preserved for metallographic observation by making emergency stops at various plunge depths. The plunging pin tool is seen to be surrounded by a very fine grained layer of recrystallized metal extending substantially below the bottom of the pin, implying a shear interface in the metal below and not at the tool-metal interface. Torque and plunge force during the initial plunge phase in Friction Stir Welding are calculated from a straight forward model based on a concept to plastic flow in the vicinity of the plunging tool compatible with structural observations. The concept: a disk of weld metal seized to and rotating with the bottom of the pin is squeezed out laterally by the plunge force and extruded upwards in a hollow cylinder around the tool. As the shear surface separating rotating disk from stationary weld metal engulfs fresh metal, the fresh metal is subjected to severe shear deformation, which results in its recrystallization. Encouraging agreement between computations and measured torque and plunge force is obtained.

Spreading dynamics of superposed liquid drops on a spinning disk

NASA Astrophysics Data System (ADS)

Sahoo, Subhadarshinee; Orpe, Ashish V.; Doshi, Pankaj

2018-01-01

We have experimentally studied simultaneous spreading of superposed drops of two Newtonian liquids on top of a horizontal spinning disk using the flow visualization technique. An inner drop of high surface tension liquid is placed centrally on the disk followed by a drop of outer liquid (lower surface tension) placed exactly above that. The disk is then rotated at a desired speed for a range of volume ratios of two liquids. Such an arrangement of two superposed liquid drops does not affect the spreading behavior of the outer liquid but influences that of the inner liquid significantly. The drop spreads to a larger extent and breaks into more fingers (Nf) as compared to the case where the same liquid is spreading in the absence of outer liquid. The experimentally observed number of fingers is compared with the prediction using available theory for single liquid. It is found that the theory over-predicts the value of Nf for the inner liquid while it is covered by an outer liquid. We provide a theoretical justification for this observation using linear stability analysis. Our analysis demonstrates that for small but finite surface tension ratio of the two liquids, the presence of the outer interface reduces the value of the most unstable wave number which is equivalent to the decrease in the number of fingers observed experimentally. Finally, sustained rotation of the disk leads to the formation of droplets at the tip of the fingers traveling outwards.

Analysis of a disk-type piezoelectric ultrasonic motor using impedance matrices.

PubMed

Kim, Young H; Ha, Sung K

2003-12-01

The dynamic behavior and the performance characteristics of the disk-type traveling wave piezoelectric ultrasonic motors (USM) are analyzed using impedance matrices. The stator is divided into three coupled subsystems: an inner metal disk, a piezoelectric annular actuator with segmented electrodes, and an outer metal disk with teeth. The effects of both shear deformation and rotary inertia are taken into account in deriving an impedance matrix for the piezoelectric actuator. The impedance matrices for each subsystem then are combined into a global impedance matrix using continuity conditions at the interfaces. A comparison is made between the impedance matrix model and the three-dimensional finite element model of the piezoelectric stator, obtaining the resonance and antiresonance frequencies and the effective electromechanical coupling factors versus circumferential mode numbers. Using the calculated resonance frequency and the vibration modes for the stator and a brush model with the Coulomb friction for the stator and rotor contact, stall torque, and no-load speed versus excitation frequencies are calculated at different preloads. Performance characteristics such as speed-torque curve and the output efficiency of the USM also are estimated using the current impedance matrix and the contact model. The present impedance model can be shown to be very effective in the design of the USM.

Simple, Script-Based Science Processing Archive

NASA Technical Reports Server (NTRS)

Lynnes, Christopher; Hegde, Mahabaleshwara; Barth, C. Wrandle

2007-01-01

The Simple, Scalable, Script-based Science Processing (S4P) Archive (S4PA) is a disk-based archival system for remote sensing data. It is based on the data-driven framework of S4P and is used for data transfer, data preprocessing, metadata generation, data archive, and data distribution. New data are automatically detected by the system. S4P provides services such as data access control, data subscription, metadata publication, data replication, and data recovery. It comprises scripts that control the data flow. The system detects the availability of data on an FTP (file transfer protocol) server, initiates data transfer, preprocesses data if necessary, and archives it on readily available disk drives with FTP and HTTP (Hypertext Transfer Protocol) access, allowing instantaneous data access. There are options for plug-ins for data preprocessing before storage. Publication of metadata to external applications such as the Earth Observing System Clearinghouse (ECHO) is also supported. S4PA includes a graphical user interface for monitoring the system operation and a tool for deploying the system. To ensure reliability, S4P continuously checks stored data for integrity, Further reliability is provided by tape backups of disks made once a disk partition is full and closed. The system is designed for low maintenance, requiring minimal operator oversight.

Application of photothermal effect to manufacture ultrasonic actuators (abstract)

NASA Astrophysics Data System (ADS)

Zhang, Shu-yi; Cheng, Li-ping; Shui, Xiu-ji; Yu, Jiong; Dong, Shu-xiang

2003-01-01

Photothermal (PT) effect has been applied to manufacture disks [A. C. Tam, a lecture at the Institute of Acoustics, Nanjing University, People's Republic of China (1996)] and magnetic head sliders for disk drives [A. C. Tam, C. C. Poon, and L. Crawforth, Analyt. Sci. 17, s 419 (2001)]. Now we apply the PT effect to manufacture ultrasonic motors (actuators). Recently, the ultrasonic actuators with different ultrasonic modes, such as Rayleigh (surface acoustic) mode, Lamb (plate) mode, etc., have been developed. We have designed and fabricated two rotary motors driven by surface acoustic wave (SAW) with different frequencies, but lower than 30 MHz [L. P. Cheng, G. M. Zhang, S. Y. Zhang, J. Yu, and X. J. Shui, Ultrasonics 39, 591 (2002)]. On the SAW motors (actuators), two Rayleigh wave beams were generated and propagating along the surface of a 128° YK-LiNbO3 substrate in opposite directions with each other as a stator, and a plastic disk with balls distributed along the circle of the disk was as a rotor. For miniaturizing the rotary SAW motors, and increasing the rotation velocity, the SAW frequency must be increased. Then we improve the manufacturing technology of the mechanical structure by PT effect instead of the conventional mechanical processes of the stator and rotor of the motor. A new type of rotary SAW motor (actuator) has been fabricated, in which both SAW beams with opposite propagating directions are excited by two pairs of interdigital transducers with the frequency between 30-50 MHz. In the surface of the stator (128° YX-LiNbO3 substrate), a hole with the depth about 500 μm is impinged by a focused pulsed Nd:YAG laser beam (PT effect) between two SAW propagating ways on the 128° YX-LiNbO3 substrate for fixing the axis of the motor, with the frequency between 30-50 MHz. In the bottom of the rotor (plastic disk), a lot of crown (flange) blocks with the high of 20-30 μm and the diameter of also 20-30 μm can be made by the focused pulsed Nd:YAG laser a focused continuous Ar+ laser heating (PT effect) for contacting with the stator. The symmetrical frictional force pairs produced between the crown blocks of the rotor with the local supporting SAW deformation points of the stator around the circle of the rotor to drive the motor to rotate. This kind of rotary SAW actuator can be applied to drive a recording head of HDD with satisfactory performance.

Variations in Medical Subject Headings (MeSH) mapping: from the natural language of patron terms to the controlled vocabulary of mapped lists*

PubMed Central

Gault, Lora V.; Shultz, Mary; Davies, Kathy J.

2002-01-01

Objectives: This study compared the mapping of natural language patron terms to the Medical Subject Headings (MeSH) across six MeSH interfaces for the MEDLINE database. Methods: Test data were obtained from search requests submitted by patrons to the Library of the Health Sciences, University of Illinois at Chicago, over a nine-month period. Search request statements were parsed into separate terms or phrases. Using print sources from the National Library of Medicine, Each parsed patron term was assigned corresponding MeSH terms. Each patron term was entered into each of the selected interfaces to determine how effectively they mapped to MeSH. Data were collected for mapping success, accessibility of MeSH term within mapped list, and total number of MeSH choices within each list. Results: The selected MEDLINE interfaces do not map the same patron term in the same way, nor do they consistently lead to what is considered the appropriate MeSH term. Conclusions: If searchers utilize the MEDLINE database to its fullest potential by mapping to MeSH, the results of the mapping will vary between interfaces. This variance may ultimately impact the search results. These differences should be considered when choosing a MEDLINE interface and when instructing end users. PMID:11999175

Variations in Medical Subject Headings (MeSH) mapping: from the natural language of patron terms to the controlled vocabulary of mapped lists.

PubMed

Gault, Lora V; Shultz, Mary; Davies, Kathy J

2002-04-01

This study compared the mapping of natural language patron terms to the Medical Subject Headings (MeSH) across six MeSH interfaces for the MEDLINE database. Test data were obtained from search requests submitted by patrons to the Library of the Health Sciences, University of Illinois at Chicago, over a nine-month period. Search request statements were parsed into separate terms or phrases. Using print sources from the National Library of Medicine, Each parsed patron term was assigned corresponding MeSH terms. Each patron term was entered into each of the selected interfaces to determine how effectively they mapped to MeSH. Data were collected for mapping success, accessibility of MeSH term within mapped list, and total number of MeSH choices within each list. The selected MEDLINE interfaces do not map the same patron term in the same way, nor do they consistently lead to what is considered the appropriate MeSH term. If searchers utilize the MEDLINE database to its fullest potential by mapping to MeSH, the results of the mapping will vary between interfaces. This variance may ultimately impact the search results. These differences should be considered when choosing a MEDLINE interface and when instructing end users.

Towards Intelligent Environments: An Augmented Reality–Brain–Machine Interface Operated with a See-Through Head-Mount Display

PubMed Central

Takano, Kouji; Hata, Naoki; Kansaku, Kenji

2011-01-01

The brain–machine interface (BMI) or brain–computer interface is a new interface technology that uses neurophysiological signals from the brain to control external machines or computers. This technology is expected to support daily activities, especially for persons with disabilities. To expand the range of activities enabled by this type of interface, here, we added augmented reality (AR) to a P300-based BMI. In this new system, we used a see-through head-mount display (HMD) to create control panels with flicker visual stimuli to support the user in areas close to controllable devices. When the attached camera detects an AR marker, the position and orientation of the marker are calculated, and the control panel for the pre-assigned appliance is created by the AR system and superimposed on the HMD. The participants were required to control system-compatible devices, and they successfully operated them without significant training. Online performance with the HMD was not different from that using an LCD monitor. Posterior and lateral (right or left) channel selections contributed to operation of the AR–BMI with both the HMD and LCD monitor. Our results indicate that AR–BMI systems operated with a see-through HMD may be useful in building advanced intelligent environments. PMID:21541307

Head wave correlations in ambient noise.

PubMed

Gebbie, John; Siderius, Martin

2016-07-01

Ambient ocean noise is processed with a vertical line array to reveal coherent time-separated arrivals suggesting the presence of head wave multipath propagation. Head waves, which are critically propagating water waves created by seabed waves traveling parallel to the water-sediment interface, can propagate faster than water-only waves. Such eigenrays are much weaker than water-only eigenrays, and are often completely overshadowed by them. Surface-generated noise is different whereby it amplifies the coherence between head waves and critically propagating water-only waves, which is measured by cross-correlating critically steered beams. This phenomenon is demonstrated both experimentally and with a full wave simulation.

78 FR 32078 - Special Conditions: Gulfstream Model G280 Airplane, Enhanced Flight Vision System (EFVS) With...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-29

... document refers to a system comprised of a head-up display, imaging sensor(s), and avionics interfaces that display the sensor imagery on the HUD, and which overlay that imagery with alpha-numeric and symbolic... the sensor imagery, with or without other flight information, on a head-down display. For clarity, the...

Temperature Effect on Micelle Formation: Molecular Thermodynamic Model Revisited.

PubMed

Khoshnood, Atefeh; Lukanov, Boris; Firoozabadi, Abbas

2016-03-08

Temperature affects the aggregation of macromolecules such as surfactants, polymers, and proteins in aqueous solutions. The effect on the critical micelle concentration (CMC) is often nonmonotonic. In this work, the effect of temperature on the micellization of ionic and nonionic surfactants in aqueous solutions is studied using a molecular thermodynamic model. Previous studies based on this technique have predicted monotonic behavior for ionic surfactants. Our investigation shows that the choice of tail transfer energy to describe the hydrophobic effect between the surfactant tails and the polar solvent molecules plays a key role in the predicted CMC. We modify the tail transfer energy by taking into account the effect of the surfactant head on the neighboring methylene group. The modification improves the description of the CMC and the predicted micellar size for aqueous solutions of sodium n-alkyl sulfate, dodecyl trimethylammonium bromide (DTAB), and n-alkyl polyoxyethylene. The new tail transfer energy describes the nonmonotonic behavior of CMC versus temperature. In the DTAB-water system, we redefine the head size by including the methylene group, next to the nitrogen, in the head. The change in the head size along with our modified tail transfer energy improves the CMC and aggregation size prediction significantly. Tail transfer is a dominant energy contribution in micellar and microemulsion systems. It also promotes the adsorption of surfactants at fluid-fluid interfaces and affects the formation of adsorbed layer at fluid-solid interfaces. Our proposed modifications have direct applications in the thermodynamic modeling of the effect of temperature on molecular aggregation, both in the bulk and at the interfaces.

Cookbook Recipe to Simulate Seawater Intrusion with Standard MODFLOW

NASA Astrophysics Data System (ADS)

Schaars, F.; Bakker, M.

2012-12-01

We developed a cookbook recipe to simulate steady interface flow in multi-layer coastal aquifers with regular groundwater codes such as standard MODFLOW. The main step in the recipe is a simple transformation of the hydraulic conductivities and thicknesses of the aquifers. Standard groundwater codes may be applied to compute the head distribution in the aquifer using the transformed parameters. For example, for flow in a single unconfined aquifer, the hydraulic conductivity needs to be multiplied with 41 and the base of the aquifer needs to be set to mean sea level (for a relative seawater density of 1.025). Once the head distribution is obtained, the Ghijben-Herzberg relationship is applied to compute the depth of the interface. The recipe may be applied to quite general settings, including spatially variable aquifer properties. Any standard groundwater code may be used, as long as it can simulate unconfined flow where the transmissivity is a linear function of the head. The proposed recipe is benchmarked successfully against a number of analytic and numerical solutions.

Design of Flight Control Panel Layout using Graphical User Interface in MATLAB

NASA Astrophysics Data System (ADS)

Wirawan, A.; Indriyanto, T.

2018-04-01

This paper introduces the design of Flight Control Panel (FCP) Layout using Graphical User Interface in MATLAB. The FCP is the interface to give the command to the simulation and to monitor model variables while the simulation is running. The command accommodates by the FCP are altitude command, the angle of sideslip command, heading command, and setting command for turbulence model. The FCP was also designed to monitor the flight parameter while the simulation is running.

Techniques and applications for binaural sound manipulation in human-machine interfaces

NASA Technical Reports Server (NTRS)

Begault, Durand R.; Wenzel, Elizabeth M.

1990-01-01

The implementation of binaural sound to speech and auditory sound cues (auditory icons) is addressed from both an applications and technical standpoint. Techniques overviewed include processing by means of filtering with head-related transfer functions. Application to advanced cockpit human interface systems is discussed, although the techniques are extendable to any human-machine interface. Research issues pertaining to three-dimensional sound displays under investigation at the Aerospace Human Factors Division at NASA Ames Research Center are described.

Techniques and applications for binaural sound manipulation in human-machine interfaces

NASA Technical Reports Server (NTRS)

Begault, Durand R.; Wenzel, Elizabeth M.

1992-01-01

The implementation of binaural sound to speech and auditory sound cues (auditory icons) is addressed from both an applications and technical standpoint. Techniques overviewed include processing by means of filtering with head-related transfer functions. Application to advanced cockpit human interface systems is discussed, although the techniques are extendable to any human-machine interface. Research issues pertaining to three-dimensional sound displays under investigation at the Aerospace Human Factors Division at NASA Ames Research Center are described.

Sealing in Turbomachinery

NASA Technical Reports Server (NTRS)

Chupp, Raymond E.; Hendricks, Robert C.; Lattime, Scott B.; Steinetz, Bruce M.

2006-01-01

Clearance control is of paramount importance to turbomachinery designers and is required to meet today's aggressive power output, efficiency, and operational life goals. Excessive clearances lead to losses in cycle efficiency, flow instabilities, and hot gas ingestion into disk cavities. Insufficient clearances limit coolant flows and cause interface rubbing, overheating downstream components and damaging interfaces, thus limiting component life. Designers have put renewed attention on clearance control, as it is often the most cost effective method to enhance system performance. Advanced concepts and proper material selection continue to play important roles in maintaining interface clearances to enable the system to meet design goals. This work presents an overview of turbomachinery sealing to control clearances. Areas covered include: characteristics of gas and steam turbine sealing applications and environments, benefits of sealing, types of standard static and dynamics seals, advanced seal designs, as well as life and limitations issues.

X-Ray photoelectron spectroscopy study of radiofrequency-sputtered titanium, carbide, molybdenum carbide, and titanium boride coatings and their friction properties

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1977-01-01

Radiofrequency sputtered coatings of titanium carbide, molybdenum carbide and titanium boride were tested as wear resistant coatings on stainless steel in a pin on disk apparatus. X-ray photoelectron spectroscopy (XPS) was used to analyze the sputtered films with regard to both bulk and interface composition in order to obtain maximum film performance. Significant improvements in friction behavior were obtained when properly biased films were deposited on deliberately preoxidized substrates. XPS depth profile data showed thick graded interfaces for bias deposited films even when adherence was poor. The addition of 10 percent hydrogen to the sputtering gas produced coatings with thin poorly adherent interfaces. Results suggest that some of the common practices in the field of sputtering may be detrimental to achieving maximum adherence and optimum composition for these refractory compounds.

General-purpose interface bus for multiuser, multitasking computer system

NASA Technical Reports Server (NTRS)

Generazio, Edward R.; Roth, Don J.; Stang, David B.

1990-01-01

The architecture of a multiuser, multitasking, virtual-memory computer system intended for the use by a medium-size research group is described. There are three central processing units (CPU) in the configuration, each with 16 MB memory, and two 474 MB hard disks attached. CPU 1 is designed for data analysis and contains an array processor for fast-Fourier transformations. In addition, CPU 1 shares display images viewed with the image processor. CPU 2 is designed for image analysis and display. CPU 3 is designed for data acquisition and contains 8 GPIB channels and an analog-to-digital conversion input/output interface with 16 channels. Up to 9 users can access the third CPU simultaneously for data acquisition. Focus is placed on the optimization of hardware interfaces and software, facilitating instrument control, data acquisition, and processing.

Viewpoint 9--molecular structure of aqueous interfaces

NASA Technical Reports Server (NTRS)

Pohorille, A.; Wilson, M. A.

1993-01-01

In this review we summarize recent progress in our understanding of the structure of aqueous interfaces emerging from molecular level computer simulations. It is emphasized that the presence of the interface induces specific structural effects which, in turn, influence a wide variety of phenomena occurring near the phase boundaries. At the liquid-vapor interface, the most probable orientations of a water molecule is such that its dipole moment lies parallel to the interface, one O-H bond points toward the vapor and the other O-H bond is directed toward the liquid. The orientational distributions are broad and slightly asymmetric, resulting in an excess dipole moment pointing toward the liquid. These structural preferences persist at interfaces between water and nonpolar liquids, indicating that the interactions between the two liquids in contact are weak. It was found that liquid-liquid interfaces are locally sharp but broadened by capillary waves. One consequence of anisotropic orientations of interfacial water molecules is asymmetric interactions, with respect to the sign of the charge, of ions with the water surface. It was found that even very close to the surface ions retain their hydration shells. New features of aqueous interfaces have been revealed in studies of water-membrane and water-monolayer systems. In particular, water molecules are strongly oriented by the polar head groups of the amphiphilic phase, and they penetrate the hydrophilic head-group region, but not the hydrophobic core. At infinite dilution near interfaces, amphiphilic molecules exhibit behavior different from that in the gas phase or in bulk water. This result sheds new light on the nature of hydrophobic effect in the interfacial regions. The presence of interfaces was also shown to affect both equilibrium and dynamic components of rates of chemical reactions. Applications of continuum models to interfacial problems have been, so far, unsuccessful. This, again, underscores the importance of molecular-level information about interfaces.

Study on Effects of The Shape of Cavitator on Supercavitation Flow Field Characteristics

NASA Astrophysics Data System (ADS)

Wang, Rui; Dang, Jianjun; Yao, Zhong

2018-03-01

The cavitator is the key part of the nose of the vehicle to induce the formation of supercavity, which has an important influence in the cavity formation rate, cavity shape and cavity stability. To study the influence of the shape on the supercavitation flew field characteristics, the cavity characteristics and the resistance characteristics of different shapes of cavitator under different working conditions are obtained by combining technical methods of numerical simulation and experimental research in water tunnel. The simulation results are contrast and analyzed with the test results. The analysis results show that : in terms of the cavity size, the inverted-conic cavitator can form the biggest cavity size, followed by the disk cavitator, and the truncated-conic cavitator is the least; in terms of the cavity formation speed, the inverted-conic cavitator has the fastest cavity formation speed, then is the truncated-conic cavitator, and the disk cavitator is the least; in terms of the drag characteristic, the truncated-conic cavitator has the maximum coefficient, disk cavitator is the next, the inverted-conic cavitator is the minimal. The research conclusion can provide reference and basis for the head shape design of supercavitating underwater ordnance and the design of hydrodynamic layout.

A video, text, and speech-driven realistic 3-d virtual head for human-machine interface.

PubMed

Yu, Jun; Wang, Zeng-Fu

2015-05-01

A multiple inputs-driven realistic facial animation system based on 3-D virtual head for human-machine interface is proposed. The system can be driven independently by video, text, and speech, thus can interact with humans through diverse interfaces. The combination of parameterized model and muscular model is used to obtain a tradeoff between computational efficiency and high realism of 3-D facial animation. The online appearance model is used to track 3-D facial motion from video in the framework of particle filtering, and multiple measurements, i.e., pixel color value of input image and Gabor wavelet coefficient of illumination ratio image, are infused to reduce the influence of lighting and person dependence for the construction of online appearance model. The tri-phone model is used to reduce the computational consumption of visual co-articulation in speech synchronized viseme synthesis without sacrificing any performance. The objective and subjective experiments show that the system is suitable for human-machine interaction.

Interaction of a Model Peptide with a Water--Bilayer System

NASA Technical Reports Server (NTRS)

Pohorille, A.; Wilson, M. A.

1994-01-01

We discuss a molecular dynamics study of the alanine dipeptide at the interface between water and a glycerol-1-monooleate (GMO) bilayer. The dipeptide is interfacially active and incorporates into the bilayer without disrupting its structure. The interfacial region that is readily penetrated by the dipeptide spans the entire head group portion of the bilayer. The polar groups of the alanine dipeptide mostly remain well solvated by water and the oxygen atoms of GMO, and conformations of the dipeptide are characterized by (phi, psi) angles typical of alpha-helix and beta-sheet structures. When the molecule is deeper in the bilayer, the C(sub 7eq) state also becomes stable. The barrier to the isomerization reaction at the interface is lower than in bulk phases. After 7 ns of trajectories, the system is not fully equilibrated, due to slow collective motions involving GMO head groups. These result in decreased mobility and lower rates of isomerization of the dipeptide at the interface.

iMAST FY2003 Annual Report

DTIC Science & Technology

2003-01-01

The approach being pursued, under this program structure, is to eliminate the use of physical surfaces on the component as datum. The use of physical...will eliminate /minimize fretting and low-cycle fatigue and the blade-disk interface. This optimum coating and/or coating process will be evaluated both...Utilizes MCLB infrastructure Avoids costs associated with existing APCS Biofiltration produces no secondary emissions Biofiltration is the most

The Scalable Checkpoint/Restart Library

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

Moody, A.

The Scalable Checkpoint/Restart (SCR) library provides an interface that codes may use to worite our and read in application-level checkpoints in a scalable fashion. In the current implementation, checkpoint files are cached in local storage (hard disk or RAM disk) on the compute nodes. This technique provides scalable aggregate bandwidth and uses storage resources that are fully dedicated to the job. This approach addresses the two common drawbacks of checkpointing a large-scale application to a shared parallel file system, namely, limited bandwidth and file system contention. In fact, on current platforms, SCR scales linearly with the number of compute nodes.more » It has been benchmarked as high as 720GB/s on 1094 nodes of Atlas, which is nearly two orders of magnitude faster thanthe parallel file system.« less

Electromagnetic brake/clutch device

NASA Technical Reports Server (NTRS)

Vranish, John M. (Inventor)

1994-01-01

An electromagnetic brake/clutch device includes a drive shaft supported by at least one bearing for transmitting torque, a housing, affixed to prevent its rotation, surrounding the drive shaft, and an electromagnetically activated device within the housing to selectively prevent and allow rotation of the drive shaft. The electromagnetically activated device includes a plurality of cammed rollers to prevent counter-clockwise rotation of the drive shaft. The drive shaft includes a circumferential disk and the housing includes a reaction ring for engagement with the plurality of cammed rollers. The plurality of cammed rollers are released from engagement with the circumferential disk and the reaction ring by a plurality of tripping mechanisms within the housing. The tripping action uses the locking force to act as a release force merely by changing the boundary conditions of the roller interface angles. The tripping mechanisms include trippers for disengaging the plurality of cammed rollers and an anvil shaped portion for providing lateral movement of the trippers. The plurality of cammed rollers is preloaded to engagement with the circumferential disk and reaction ring by a spring, and is located with respect to an adjacent tripping mechanism with another spring.

Optoelectronic-cache memory system architecture.

PubMed

Chiarulli, D M; Levitan, S P

1996-05-10

We present an investigation of the architecture of an optoelectronic cache that can integrate terabit optical memories with the electronic caches associated with high-performance uniprocessors and multiprocessors. The use of optoelectronic-cache memories enables these terabit technologies to provide transparently low-latency secondary memory with frame sizes comparable with disk pages but with latencies that approach those of electronic secondary-cache memories. This enables the implementation of terabit memories with effective access times comparable with the cycle times of current microprocessors. The cache design is based on the use of a smart-pixel array and combines parallel free-space optical input-output to-and-from optical memory with conventional electronic communication to the processor caches. This cache and the optical memory system to which it will interface provide a large random-access memory space that has a lower overall latency than that of magnetic disks and disk arrays. In addition, as a consequence of the high-bandwidth parallel input-output capabilities of optical memories, fault service times for the optoelectronic cache are substantially less than those currently achievable with any rotational media.

Dust Dynamics in Protoplanetary Disks: Parallel Computing with PVM

NASA Astrophysics Data System (ADS)

de La Fuente Marcos, Carlos; Barge, Pierre; de La Fuente Marcos, Raúl

2002-03-01

We describe a parallel version of our high-order-accuracy particle-mesh code for the simulation of collisionless protoplanetary disks. We use this code to carry out a massively parallel, two-dimensional, time-dependent, numerical simulation, which includes dust particles, to study the potential role of large-scale, gaseous vortices in protoplanetary disks. This noncollisional problem is easy to parallelize on message-passing multicomputer architectures. We performed the simulations on a cache-coherent nonuniform memory access Origin 2000 machine, using both the parallel virtual machine (PVM) and message-passing interface (MPI) message-passing libraries. Our performance analysis suggests that, for our problem, PVM is about 25% faster than MPI. Using PVM and MPI made it possible to reduce CPU time and increase code performance. This allows for simulations with a large number of particles (N ~ 105-106) in reasonable CPU times. The performances of our implementation of the pa! rallel code on an Origin 2000 supercomputer are presented and discussed. They exhibit very good speedup behavior and low load unbalancing. Our results confirm that giant gaseous vortices can play a dominant role in giant planet formation.

The effect of operative fit and hydroxyapatite coating on the mechanical and biological response to porous implants.

PubMed

Dalton, J E; Cook, S D; Thomas, K A; Kay, J F

1995-01-01

Femoral intramedullary implants were constructed by threading 4.0-millimeter-thick disks with a titanium-alloy (Ti-6Al-4V) porous bead coating onto a two-millimeter-diameter threaded rod. Each porous-coated disk, which was 6.0, 8.0, 9.0, or 10.0 millimeters in diameter, was separated by a two-millimeter-thick acrylic disk with a diameter of ten millimeters. Implants with and without a hydroxyapatite coating of twenty-five micrometers were inserted into fifteen skeletally mature adult mongrel dogs. The femoral canal was sequentially reamed bilaterally to a ten-millimeter diameter, resulting in uniform initial implant-bone interface gaps of 0.0, 0.5, 1.0, and 2.0 millimeters. Each animal received paired hydroxyapatite-coated and uncoated implants. Three animals each were killed at four, eight, twelve, twenty-four, and fifty-two weeks after the implantation. The harvested femora were sectioned through the acrylic spacers, transverse to the long axis, to produce individual push-out test specimens for mechanical testing. Characteristics of interface attachment were determined with test fixtures that supported the surrounding bone to within 150 micrometers of the interface. Histological sections were prepared, and the amount of bone within the porous structure and the amount of the original gap that was filled with new bone were quantified with a computerized video image-analysis system. Mechanical attachment strength and bone ingrowth were found to increase with the time after implantation and with a decrease in the size of the gap. Placement of the implant in proximal (cancellous) compared with distal (cortical) locations had no significant effect on the strength of attachment, bone ingrowth, or gap-filling. However, implants with a large initial gap (1.0 or 2.0 millimeters) demonstrated greater attachment strength in cancellous bone than in cortical bone. With a few exceptions, hydroxyapatite-coated implants with an initial gap of 1.0 millimeter or less demonstrated significantly increased mechanical attachment strength and bone ingrowth at all time-periods. Interface attachment strengths were positively correlated with bone ingrowth, the time after implantation, the use of a hydroxyapatite coating, and decreasing initial gap size. Initial implant-bone apposition is thought to be a prerequisite for good biological fixation. This apposition is often not achieved because of the design of the implant or instruments and the operative technique. Poor initial fit during the operation may decrease the longevity of the implant. The results of the present study indicate that attachment strength and bone ingrowth are significantly affected by gaps in the interface, particularly those of more than 1.0 millimeter.(ABSTRACT TRUNCATED AT 400 WORDS)

X-Antenna: A graphical interface for antenna analysis codes

NASA Technical Reports Server (NTRS)

Goldstein, B. L.; Newman, E. H.; Shamansky, H. T.

1995-01-01

This report serves as the user's manual for the X-Antenna code. X-Antenna is intended to simplify the analysis of antennas by giving the user graphical interfaces in which to enter all relevant antenna and analysis code data. Essentially, X-Antenna creates a Motif interface to the user's antenna analysis codes. A command-file allows new antennas and codes to be added to the application. The menu system and graphical interface screens are created dynamically to conform to the data in the command-file. Antenna data can be saved and retrieved from disk. X-Antenna checks all antenna and code values to ensure they are of the correct type, writes an output file, and runs the appropriate antenna analysis code. Volumetric pattern data may be viewed in 3D space with an external viewer run directly from the application. Currently, X-Antenna includes analysis codes for thin wire antennas (dipoles, loops, and helices), rectangular microstrip antennas, and thin slot antennas.

Formatting scripts with computers and Extended BASIC.

PubMed

Menning, C B

1984-02-01

A computer program, written in the language of Extended BASIC, is presented which enables scripts, for educational media, to be quickly written in a nearly unformatted style. From the resulting script file, stored on magnetic tape or disk, the computer program formats the script into either a storyboard , a presentation, or a narrator 's script. Script headings and page and paragraph numbers are automatic features in the word processing. Suggestions are given for making personal modifications to the computer program.

Optical vibration measurement of mechatronics devices

NASA Astrophysics Data System (ADS)

Yanabe, Shigeo

1993-09-01

An optical vibration measuring system which enables to detect both linear and angular displacement of 25 nm and 5 prad was developed. The system is mainly composed of a He-Ne laser, a displacement detecting photo-diode and lenses, and has linear and angular displacement magnification mechanism using two different principles of optical lever. The system was applied to measure vibrational characteristics of magnetic head slider of hard disk drives and to measure stator teeth driving velocities of ultrasonic motor.

The Dimeric Architecture of Checkpoint Kinases Mec1ATR and Tel1ATM Reveal a Common Structural Organization.

PubMed

Sawicka, Marta; Wanrooij, Paulina H; Darbari, Vidya C; Tannous, Elias; Hailemariam, Sarem; Bose, Daniel; Makarova, Alena V; Burgers, Peter M; Zhang, Xiaodong

2016-06-24

The phosphatidylinositol 3-kinase-related protein kinases are key regulators controlling a wide range of cellular events. The yeast Tel1 and Mec1·Ddc2 complex (ATM and ATR-ATRIP in humans) play pivotal roles in DNA replication, DNA damage signaling, and repair. Here, we present the first structural insight for dimers of Mec1·Ddc2 and Tel1 using single-particle electron microscopy. Both kinases reveal a head to head dimer with one major dimeric interface through the N-terminal HEAT (named after Huntingtin, elongation factor 3, protein phosphatase 2A, and yeast kinase TOR1) repeat. Their dimeric interface is significantly distinct from the interface of mTOR complex 1 dimer, which oligomerizes through two spatially separate interfaces. We also observe different structural organizations of kinase domains of Mec1 and Tel1. The kinase domains in the Mec1·Ddc2 dimer are located in close proximity to each other. However, in the Tel1 dimer they are fully separated, providing potential access of substrates to this kinase, even in its dimeric form. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Centrifugal microfluidic platform for ultrasensitive detection of botulinum toxin

DOE PAGES

Koh, Chung -Yan; Schaff, Ulrich Y.; Sandstone Diagnostics, Livermore, CA; ...

2014-12-18

In this study, we present an innovative centrifugal microfluidic immunoassay platform (SpinDx) to address the urgent biodefense and public health need for ultrasensitive point-of-care/incident detection of botulinum toxin. The simple, sample-to-answer centrifugal microfluidic immunoassay approach is based on binding of toxins to antibody-laden capture particles followed by sedimentation of the particles through a density-media in a microfluidic disk and quantification by laser-induced fluorescence. A blind, head-to-head comparison study of SpinDx versus the gold-standard mouse bioassay demonstrates 100-fold improvement in sensitivity (limit of detection = 0.09 pg/mL), while achieving total sample-to-answer time of <30 min with 2-μL required volume of themore » unprocessed sample. We further demonstrate quantification of botulinum toxin in both exogeneous (human blood and serum spiked with toxins) and endogeneous (serum from mice intoxicated via oral, intranasal, and intravenous routes) samples. SpinDx can analyze, without any sample preparation, multiple sample types including whole blood, serum, and food. It is readily expandable to additional analytes as the assay reagents (i.e., the capture beads and detection antibodies) are disconnected from the disk architecture and the reader, facilitating rapid development of new assays. SpinDx can also serve as a general-purpose immunoassay platform applicable to diagnosis of other conditions and diseases.« less

On the start up of supersonic underexpanded jets

NASA Astrophysics Data System (ADS)

Lacerda, Nehemias Lima

An impulsively started jet can be formed by a gas confined in a high pressure reservoir that escapes suddenly through an exit orifice, into a controlled atmosphere. Supersonic gas jets of this type are unsteady and differ from the steady jet that develops later by the presence of a bow shock, a jet head and a nonstationary Mach disk. The effects of the pressure ratio between the high pressure gas inside the reservoir and the lower pressure atmospheric gas, as well as the gas combination used, are studied experimentally. The gases used for the jet and the atmosphere were selected from helium, nitrogen and sulfur hexafluoride. The data acquisition consisted of: high resolution flash photography to obtain detail from the pictures; high-speed movie pictures to obtain the time development of selected features; and fast-response pressure transducers located at the reservoir end plate, the tank end plate and the jet exit. The initial development of the jet is highly time dependent. During this phase, the shape that the jet assumes varies with pressure ratio and with the choice of gas. In particular an extremely light gas exhausting into a heavy atmosphere, exhibits an uncommon shape. It develops as a bubble wrapped by the bow shock, that increases its volume with flow time and pressure ratio. As the pressure ratio increases, it becomes more tightly wrapped by the bow shock. At later times the jet assumes conventional linear growth. After the jet starts, a Mach disk is observed close to the jet exit which moves downstream as the exit pressure builds up. The monotonic increase in exit pressure is caused by the slow breaking of the diaphragm. The position of the Mach disk is furthest from the jet exit when the exit pressure is a maximum. After that it oscillates around the location predicted by the steady theory of Ashkenas and Sherman (1966) at a frequency close to one of the resonant frequencies of the reservoir. The features observed for the inner structure of the jet were verified to agree with those obtained for impulsive flow generated by a muzzle blast. The frontal part of the jet forms the jet head, whose shape changes with the flow conditions. The initial evolution of the jet head is linear but after propagating a distance of around ten exit diameters, it reaches asymptotic behavior with an evolution that is approximately proportional to square root of time. The head creates a bow shock ahead of it that propagates downstream and increases the pressure of the atmospheric gas. This bow shock was found to be less attenuated than in spherically symmetric explosions. The asymptotic behavior of the bow shock was reached after about eight exit diameters.

A Discovery of a Compact High Velocity Cloud-Galactic Supershell System

NASA Astrophysics Data System (ADS)

Park, Geumsook; Koo, Bon-Chul; Kang, Ji-hyun; Gibson, Steven J.; Peek, Joshua Eli Goldston; Douglas, Kevin A.; Korpela, Eric J.; Heiles, Carl E.

2017-01-01

High velocity clouds (HVCs) are neutral hydrogen (HI) gas clouds having very different radial velocities from those of the Galactic disk material. While some large HVC complexes are known to be gas streams tidally stripped from satellite galaxies of the Milky Way, there are relatively isolated and small angular-sized HVCs, so called “compact HVCs (CHVCs)”, the origin of which remains controversial. There are about 300 known CHVCs in the Milky Way, and many of them show a head-tail structure, implying a ram pressure interaction with the diffuse Galactic halo gas. It is, however, not clear whether CHVCs are completely dissipated in the Galactic halo to feed the multi-phase circumgalactic medium or they can survive their trip through the halo and collide with the Galactic disk. The colliding CHVCs may leave a gigantic trail in the disk, and it had been suggested that some of HI supershells that require ≧ 3 x 1052 erg may be produced by the collision of such HVCs.Here we report the detection of a kiloparsec (kpc)-size supershell in the outskirts of the Milky Way with the compact HVC 040+01-282 (hereafter, CHVC040) at its geometrical center using the “Inner-Galaxy Arecibo L-band Feed Array” HI 21 cm survey data. The morphological and physical properties of both objects suggest that CHVC040, which is either a fragment of a nearby disrupted galaxy or a cloud that originated from an intergalactic accreting flow, collided with the disk ˜5 Myr ago to form the supershell. Our results show that some compact HVCs can survive their trip through the Galactic halo and inject energy and momentum into the Milky Way disk.

Measuring Presence in Virtual Environments

DTIC Science & Technology

1994-10-01

viewpoint to change what they see, or to reposition their head to affect binaural hearing, or to search the environment haptically, they will experience a...increase presence in an alternate environment. For example a head mounted display that isolates the user from the real world may increase the sense...movement interface devices such as treadmills and trampolines , different gloves, and auditory equipment. Even as a low end technological implementation of

THE ORIGIN OF THE HOT GAS IN THE GALACTIC HALO: TESTING GALACTIC FOUNTAIN MODELS' X-RAY EMISSION

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

Henley, David B.; Shelton, Robin L.; Kwak, Kyujin

2015-02-20

We test the X-ray emission predictions of galactic fountain models against XMM-Newton measurements of the emission from the Milky Way's hot halo. These measurements are from 110 sight lines, spanning the full range of Galactic longitudes. We find that a magnetohydrodynamical simulation of a supernova-driven interstellar medium, which features a flow of hot gas from the disk to the halo, reproduces the temperature but significantly underpredicts the 0.5-2.0 keV surface brightness of the halo (by two orders of magnitude, if we compare the median predicted and observed values). This is true for versions of the model with and without anmore » interstellar magnetic field. We consider different reasons for the discrepancy between the model predictions and the observations. We find that taking into account overionization in cooled halo plasma, which could in principle boost the predicted X-ray emission, is unlikely in practice to bring the predictions in line with the observations. We also find that including thermal conduction, which would tend to increase the surface brightnesses of interfaces between hot and cold gas, would not overcome the surface brightness shortfall. However, charge exchange emission from such interfaces, not included in the current model, may be significant. The faintness of the model may also be due to the lack of cosmic ray driving, meaning that the model may underestimate the amount of material transported from the disk to the halo. In addition, an extended hot halo of accreted material may be important, by supplying hot electrons that could boost the emission of the material driven out from the disk. Additional model predictions are needed to test the relative importance of these processes in explaining the observed halo emission.« less

Slip and accommodation coefficients from rarefaction and roughness in rotating microscale disk flows

NASA Astrophysics Data System (ADS)

Blanchard, Danny; Ligrani, Phil

2007-06-01

Accommodation coefficients are determined from experimental results and analysis based on the Navier-Stokes equations for rotation-induced flows in C-shaped fluid chamber passages formed between a rotating disk and a stationary surface. A first-order boundary condition is used to model the slip flow. The fluid chamber passage height ranges from 6.85to29.2μm to give Knudsen numbers from 0.0025 to 0.031 for air and helium. In all cases, roughness size is large compared to molecular mean free path. The unique method presented for deducing tangential momentum accommodation coefficients gives values with less uncertainty compared to procedures that rely on flows in stationary tubes and channels. When channel height is defined at the tops of the roughness elements, slip velocity magnitudes and associated accommodation coefficients are a result of rarefaction at solid-gas interfaces and shear at the gas-gas interfaces. With this arrangement, tangential accommodation coefficients obtained with this approach decrease, and slip velocity magnitudes increase, at a particular value of Knudsen number, as the level of surface roughness increases. At values of the mean roughness height greater than 500nm, accommodation coefficients then appear to be lower in air flows than in helium flows, when compared for a particular roughness configuration. When channel height is defined midway between the crests and troughs of the roughness elements, nondimensional pressure rise data show little or no dependence on the level of disk surface roughness and working fluid. With this arrangement, slip is largely independent of surface roughness magnitude and mostly due to rarefaction, provided the appropriate channel height is chosen to define the roughness height.

The Origin of the Hot Gas in the Galactic Halo: Testing Galactic Fountain Models' X-Ray Emission

NASA Astrophysics Data System (ADS)

Henley, David B.; Shelton, Robin L.; Kwak, Kyujin; Hill, Alex S.; Mac Low, Mordecai-Mark

2015-02-01

We test the X-ray emission predictions of galactic fountain models against XMM-Newton measurements of the emission from the Milky Way's hot halo. These measurements are from 110 sight lines, spanning the full range of Galactic longitudes. We find that a magnetohydrodynamical simulation of a supernova-driven interstellar medium, which features a flow of hot gas from the disk to the halo, reproduces the temperature but significantly underpredicts the 0.5-2.0 keV surface brightness of the halo (by two orders of magnitude, if we compare the median predicted and observed values). This is true for versions of the model with and without an interstellar magnetic field. We consider different reasons for the discrepancy between the model predictions and the observations. We find that taking into account overionization in cooled halo plasma, which could in principle boost the predicted X-ray emission, is unlikely in practice to bring the predictions in line with the observations. We also find that including thermal conduction, which would tend to increase the surface brightnesses of interfaces between hot and cold gas, would not overcome the surface brightness shortfall. However, charge exchange emission from such interfaces, not included in the current model, may be significant. The faintness of the model may also be due to the lack of cosmic ray driving, meaning that the model may underestimate the amount of material transported from the disk to the halo. In addition, an extended hot halo of accreted material may be important, by supplying hot electrons that could boost the emission of the material driven out from the disk. Additional model predictions are needed to test the relative importance of these processes in explaining the observed halo emission.

System and method for manipulating domain pinning and reversal in ferromagnetic materials

DOEpatents

Silevitch, Daniel M.; Rosenbaum, Thomas F.; Aeppli, Gabriel

2013-10-15

A method for manipulating domain pinning and reversal in a ferromagnetic material comprises applying an external magnetic field to a uniaxial ferromagnetic material comprising a plurality of magnetic domains, where each domain has an easy axis oriented along a predetermined direction. The external magnetic field is applied transverse to the predetermined direction and at a predetermined temperature. The strength of the magnetic field is varied at the predetermined temperature, thereby isothermally regulating pinning of the domains. A magnetic storage device for controlling domain dynamics includes a magnetic hard disk comprising a uniaxial ferromagnetic material, a magnetic recording head including a first magnet, and a second magnet. The ferromagnetic material includes a plurality of magnetic domains each having an easy axis oriented along a predetermined direction. The second magnet is positioned adjacent to the magnetic hard disk and is configured to apply a magnetic field transverse to the predetermined direction.

Spin-polarized scanning tunneling microscopy experiments on the rough surface of a polycrystalline NiFe film with a fine magnetic tip sensitive to a well-defined magnetization component

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

Matsuyama, H., E-mail: matsu@phys.sci.hokudai.ac.jp; Nara, D.; Kageyama, R.

We developed a micrometer-sized magnetic tip integrated onto the write head of a hard disk drive for spin-polarized scanning tunneling microscopy (SP-STM) in the modulated tip magnetization mode. Using SP-STM, we measured a well-defined in-plane spin-component of the tunneling current of the rough surface of a polycrystalline NiFe film. The spin asymmetry of the NiFe film was about 1.3% within the bias voltage range of -3 to 1 V. We obtained the local spin component image of the sample surface, switching the magnetic field of the sample to reverse the sample magnetization during scanning. We also obtained a spin imagemore » of the rough surface of a polycrystalline NiFe film evaporated on the recording medium of a hard disk drive.« less

An analytic approach to optimize tidal turbine fields

NASA Astrophysics Data System (ADS)

Pelz, P.; Metzler, M.

2013-12-01

Motivated by global warming due to CO2-emission various technologies for harvesting of energy from renewable sources are developed. Hydrokinetic turbines get applied to surface watercourse or tidal flow to gain electrical energy. Since the available power for hydrokinetic turbines is proportional to the projected cross section area, fields of turbines are installed to scale shaft power. Each hydrokinetic turbine of a field can be considered as a disk actuator. In [1], the first author derives the optimal operation point for hydropower in an open-channel. The present paper concerns about a 0-dimensional model of a disk-actuator in an open-channel flow with bypass, as a special case of [1]. Based on the energy equation, the continuity equation and the momentum balance an analytical approach is made to calculate the coefficient of performance for hydrokinetic turbines with bypass flow as function of the turbine head and the ratio of turbine width to channel width.

A New Method for Carbon Isotopic Analysis of Nanogram Quantities of Carbon from Dissolved Chitin Using A Spooling-wire Microcombustion Interface

NASA Astrophysics Data System (ADS)

Zhao, Y.; Nelson, D. M.; Clegg, B. F.; Berry, J.; Hu, F.

2016-12-01

δ13C analysis of specific taxa or compounds is commonly used for investigating past environmental change, including methane dynamics in lakes. However, most analytical methods require large sample sizes, prohibiting routine analysis of fossils of individual taxa found in sediment deposits. For example, 10-100 individual head capsules of fossil midges are required for δ13C analysis using an elemental analyzer (EA) interfaced with an isotope-ratio mass spectrometer (IRMS). Here we present a new method that uses a spooling-wire microcombustion (SWiM) device interfaced with an IRMS for measuring δ13C values of carbon dissolved from individual head capsules of chitinous aquatic zooplankton. We extracted chitin (a major biochemical component of insect exoskeleton) from modern midge material obtained from four commercial suppliers. We first assessed the effects of sample treatments on carbon yields and δ13C values of dissolved chitin by varying the concentration of HCl used for dissolution, the duration of reaction in HCl, and the temperature of dissolution. We then investigated potential fractionation of carbon isotopes associated with chitin dissolution, by comparing δ13C values of dissolved chitin obtained via SWiM-IRMS with those from untreated head capsules obtained via a EA-IRMS. The average δ13C values of untreated head capsules varied between -25.1 and -30.1‰. Higher acid concentrations and temperatures, as well as longer reaction times, increased dissolution of carbon from the head capsules and the precision of δ13C values. For example, carbon yields from reaction of head capsules with 6N HCl at 25°C increased from 1 to 3 Vs as reaction times increased from 1 to 24 hours. Acid concentration and reaction time had the greatest influence on carbon yields and isotopic precision. The δ13C values of dissolved chitin mirrored the δ13C values of untreated head capsules with minimal offset of absolute values, which suggests no systematic fractionation associated with dissolution. Overall, these results indicate that carbon isotopic analysis of dissolved chitin using the SWiM-IRMS system offers a reliable new method to determine taxa-specific δ13C values for chitinous aquatic zooplankton. In ongoing work, we are applying this tool to reconstruct past methane dynamics in Arctic lakes during the Holocene.

40 CFR 1.21 - General.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-cutting Agency headquarters and regional issues and conduct programs with respect to EPA's interface with...) The Office of General Counsel; and (e) Nine operational offices, each headed by an Assistant...

Preliminary Design and Evaluation of Portable Electronic Flight Progress Strips

NASA Technical Reports Server (NTRS)

Doble, Nathan A.; Hansman, R. John

2002-01-01

There has been growing interest in using electronic alternatives to the paper Flight Progress Strip (FPS) for air traffic control. However, most research has been centered on radar-based control environments, and has not considered the unique operational needs of the airport air traffic control tower. Based on an analysis of the human factors issues for control tower Decision Support Tool (DST) interfaces, a requirement has been identified for an interaction mechanism which replicates the advantages of the paper FPS (e.g., head-up operation, portability) but also enables input and output with DSTs. An approach has been developed which uses a Portable Electronic FPS that has attributes of both a paper strip and an electronic strip. The prototype flight strip system uses Personal Digital Assistants (PDAs) to replace individual paper strips in addition to a central management interface which is displayed on a desktop computer. Each PDA is connected to the management interface via a wireless local area network. The Portable Electronic FPSs replicate the core functionality of paper flight strips and have additional features which provide a heads-up interface to a DST. A departure DST is used as a motivating example. The central management interface is used for aircraft scheduling and sequencing and provides an overview of airport departure operations. This paper will present the design of the Portable Electronic FPS system as well as preliminary evaluation results.

Hands-Free, Heads-Up Control System for Unmanned Ground Vehicles

DTIC Science & Technology

2011-08-10

interface evaluation Industry evaluated two commercial-off-the-shelf (COTS) brain computer interfaces from two companies – Neurosky and Emotiv ...useless, resulting in very low command recognition accuracy. In addition, latency issues plagued the system. Figure 6 Emotiv Headset The... Emotiv system, unlike the Neurosky, required great effort to use and calibrate. It requires 16 foam tips to be wet with saline solution and then

Virtual interface environment workstations

NASA Technical Reports Server (NTRS)

Fisher, S. S.; Wenzel, E. M.; Coler, C.; Mcgreevy, M. W.

1988-01-01

A head-mounted, wide-angle, stereoscopic display system controlled by operator position, voice and gesture has been developed at NASA's Ames Research Center for use as a multipurpose interface environment. This Virtual Interface Environment Workstation (VIEW) system provides a multisensory, interactive display environment in which a user can virtually explore a 360-degree synthesized or remotely sensed environment and can viscerally interact with its components. Primary applications of the system are in telerobotics, management of large-scale integrated information systems, and human factors research. System configuration, research scenarios, and research directions are described.

Pellet to Part Manufacturing System for CNCs

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

Roschli, Alex C.; Love, Lonnie J.; Post, Brian K.

Oak Ridge National Laboratory’s Manufacturing Demonstration Facility worked with Hybrid Manufacturing Technologies to develop a compact prototype composite additive manufacturing head that can effectively extrude injection molding pellets. The head interfaces with conventional CNC machine tools enabling rapid conversion of conventional machine tools to additive manufacturing tools. The intent was to enable wider adoption of Big Area Additive Manufacturing (BAAM) technology and combine BAAM technology with conventional machining systems.

Capacitor electrode stimulates nerve or muscle without oxidation-reduction reactions.

PubMed

Guyton, D L; Hambrecht, F T

1973-07-06

Porous tantalum disks, available as "slugs" from the capacitor industry, have large available surface area and a thin insulating coating of tantalum pentoxide. When implanted, they fill with extracellular fluid and operate as capacitor-stimulating electrodes having high capacitance per unit volume. Capable of stimulating excitable tissute without generating electrochemical by-products, these electrodes should provide a safer interface between neural prosthetic devices and human tissue.

Noise Reduction in Brainwaves by Using Both EEG Signals and Frontal Viewing Camera Images

PubMed Central

Bang, Jae Won; Choi, Jong-Suk; Park, Kang Ryoung

2013-01-01

Electroencephalogram (EEG)-based brain-computer interfaces (BCIs) have been used in various applications, including human–computer interfaces, diagnosis of brain diseases, and measurement of cognitive status. However, EEG signals can be contaminated with noise caused by user's head movements. Therefore, we propose a new method that combines an EEG acquisition device and a frontal viewing camera to isolate and exclude the sections of EEG data containing these noises. This method is novel in the following three ways. First, we compare the accuracies of detecting head movements based on the features of EEG signals in the frequency and time domains and on the motion features of images captured by the frontal viewing camera. Second, the features of EEG signals in the frequency domain and the motion features captured by the frontal viewing camera are selected as optimal ones. The dimension reduction of the features and feature selection are performed using linear discriminant analysis. Third, the combined features are used as inputs to support vector machine (SVM), which improves the accuracy in detecting head movements. The experimental results show that the proposed method can detect head movements with an average error rate of approximately 3.22%, which is smaller than that of other methods. PMID:23669713

A hollow coaxial cable Fabry-Pérot resonator for liquid dielectric constant measurement

NASA Astrophysics Data System (ADS)

Zhu, Chen; Zhuang, Yiyang; Chen, Yizheng; Huang, Jie

2018-04-01

We report, for the first time, a low-cost and robust homemade hollow coaxial cable Fabry-Pérot resonator (HCC-FPR) for measuring liquid dielectric constant. In the HCC design, the traditional dielectric insulating layer is replaced by air. A metal disk is welded onto the end of the HCC serving as a highly reflective reflector, and an open cavity is engineered on the HCC. After the open cavity is filled with the liquid analyte (e.g., water), the air-liquid interface acts as a highly reflective reflector due to large impedance mismatch. As a result, an HCC-FPR is formed by the two highly reflective reflectors, i.e., the air-liquid interface and the metal disk. We measured the room temperature dielectric constant for ethanol/water mixtures with different concentrations using this homemade HCC-FPR. Monitoring the evaporation of ethanol in ethanol/water mixtures was also conducted to demonstrate the ability of the sensor for continuously monitoring the change in dielectric constant. The results revealed that the HCC-FPR could be a promising evaporation rate detection platform with high performance. Due to its great advantages, such as high robustness, simple configuration, and ease of fabrication, the novel HCC-FPR based liquid dielectric constant sensor is believed to be of high interest in various fields.

A hollow coaxial cable Fabry-Pérot resonator for liquid dielectric constant measurement.

PubMed

Zhu, Chen; Zhuang, Yiyang; Chen, Yizheng; Huang, Jie

2018-04-01

We report, for the first time, a low-cost and robust homemade hollow coaxial cable Fabry-Pérot resonator (HCC-FPR) for measuring liquid dielectric constant. In the HCC design, the traditional dielectric insulating layer is replaced by air. A metal disk is welded onto the end of the HCC serving as a highly reflective reflector, and an open cavity is engineered on the HCC. After the open cavity is filled with the liquid analyte (e.g., water), the air-liquid interface acts as a highly reflective reflector due to large impedance mismatch. As a result, an HCC-FPR is formed by the two highly reflective reflectors, i.e., the air-liquid interface and the metal disk. We measured the room temperature dielectric constant for ethanol/water mixtures with different concentrations using this homemade HCC-FPR. Monitoring the evaporation of ethanol in ethanol/water mixtures was also conducted to demonstrate the ability of the sensor for continuously monitoring the change in dielectric constant. The results revealed that the HCC-FPR could be a promising evaporation rate detection platform with high performance. Due to its great advantages, such as high robustness, simple configuration, and ease of fabrication, the novel HCC-FPR based liquid dielectric constant sensor is believed to be of high interest in various fields.

Molecular Packing of Amiphiphiles with Crown Polar Heads at the Air-Water Interface

NASA Astrophysics Data System (ADS)

Larson, K.; Vaknin, D.; Villavicencio, O.; McGrath, D.; Tsukruk, V. V.

2002-03-01

An amphiphilic compound containing a benzyl-15-crown-5 focal point, azobenzene spacer, and a dodecyl tail as a peripheral group has been investigated at the air-water interface. X-ray grazing incident diffraction and reflectivity were preformed on the Langmuir monolayers to elucidate molecular packing and orientation. At high surface pressure, we observed intralayer packing of the alkyl tails with doubling parameters of the conventional orthorhombic unit cell (supercell) and long-range positional ordering. High tilt of the alkyl tails of about 58º from the surface normal was a signature of molecular packing caused by a large mismatch between the cross-sectional areas of the polar heads and the alkyl tail. Higher generation molecules of the same series display straight tail orientation and hexagonal lateral packing.

New generation of 3D desktop computer interfaces

NASA Astrophysics Data System (ADS)

Skerjanc, Robert; Pastoor, Siegmund

1997-05-01

Today's computer interfaces use 2-D displays showing windows, icons and menus and support mouse interactions for handling programs and data files. The interface metaphor is that of a writing desk with (partly) overlapping sheets of documents placed on its top. Recent advances in the development of 3-D display technology give the opportunity to take the interface concept a radical stage further by breaking the design limits of the desktop metaphor. The major advantage of the envisioned 'application space' is, that it offers an additional, immediately perceptible dimension to clearly and constantly visualize the structure and current state of interrelations between documents, videos, application programs and networked systems. In this context, we describe the development of a visual operating system (VOS). Under VOS, applications appear as objects in 3-D space. Users can (graphically connect selected objects to enable communication between the respective applications. VOS includes a general concept of visual and object oriented programming for tasks ranging from, e.g., low-level programming up to high-level application configuration. In order to enable practical operation in an office or at home for many hours, the system should be very comfortable to use. Since typical 3-D equipment used, e.g., in virtual-reality applications (head-mounted displays, data gloves) is rather cumbersome and straining, we suggest to use off-head displays and contact-free interaction techniques. In this article, we introduce an autostereoscopic 3-D display and connected video based interaction techniques which allow viewpoint-depending imaging (by head tracking) and visually controlled modification of data objects and links (by gaze tracking, e.g., to pick, 3-D objects just by looking at them).

Monolayers of the lipid derivatives of isoniazid at the air/water interface and the formation of self-assembled nanostructures in water.

PubMed

Jin, Yiguang; Chen, Shufeng; Xin, Rui; Zhou, Yisheng

2008-07-15

Isoniazid (INH, isonicotinic acid hydrazide) is one of the most commonly used anti-tubercular drugs. However, resistance of Mycobacterium tuberculosis strains to anti-mycobacterial agents including INH is an increasing problem worldwide. Development of new anti-mycobacterial agents thus has attracted attention. Five lipid derivatives of INH were prepared in this study. They formed monolayers at the air/water interface, and some nanostructures with different morphologies were obtained through molecular self-assembly in water. The derivatives included one fatty acyl derivative containing a 12-C hydrocarbon-long chain (1), three fatty alcohol derivatives with a succinyl as spacer and an 8, 12 or 16-C hydrocarbon-long chain (2, 3 and 4), and one tetrahydro-2H-1,3,5-thiadiazine-2-thione (THTT) derivative containing a 12-C hydrocarbon-long chain (5). The surface pressure-area isotherms depended on the volume and configuration of heads and the length of tails of derivatives. Compound 2 had a relatively large head and a short tail, easily standing uprightly at the interface. Under a certain surface pressure, the linear polar head groups of 3 could be partly squeezed out and insert into subphase because the length of heads were comparable to the one of tails. The very long tails of 4 always maintained above the interface and led to a high collapse pressure. Compound 5 possessed an extended and large head consisting of the THTT and INH groups so that the relatively short tails tilted at the interface and difficultly contact with each other. The THTT rings might be partly squeezed out and enter into air under a certain surface pressure. The self-assembly behaviours of derivatives in water depended on the molecular configuration and agreed with the corresponding monolayer behaviours. The flexible and medium-long tails (1 and 3) led to the derivatives to form nanoscale vesicles, though the short or very long tails did not (2 and 4). Interestingly, intermolecular hydrogen bonding could occur between the molecules of 5, and improve the derivative forming helical nanofibres other than vesicles. The molecular self-assembly of INH's lipid derivatives was explored in details in this study. The formation mechanisms of self-assembled nanostructures were analyzed. Various types of self-assembled nanostructures were obtained and the formation mechanisms were analyzed. The relationship between the self-assembly and the molecular configuration of amphiphilic derivatives was also revealed. The lipid derivatives of INH show promising anti-Mycobacterium action because the amphiphilic prodrugs allow for better penetration of the bacterial cells. The self-assembled nanostructures may likely be the potential self-assembled drug delivery systems for tuberculosis therapy.

Hydrodynamic stability of jets produced by mass accreting systems

NASA Technical Reports Server (NTRS)

Hardee, P. E.

1982-01-01

The existing model for pulsed X-ray emission from the source Hercules X-1 is reviewed. A necessary part of this model is a processing accretion disk which turns the source on and off with 35 day cycle. It is usually assumed that precession of the primary star in this binary system, Hz Hercules, slaves the disk to its precession rate. This model can account for the system behavior in a qualitative manner. Precession of Hz Hercules with 35 day period requires precession of the binary orbit. Pulse arrival times from Herc X-1 have been analyzed for orbital precession. The inclusion of precession does not significantly improve the results obtained assuming a non-precessing orbit. The fluid dynamical stability of extra-galactic jets and the possible consequences of Kelvin-Helmholtz instability at the jet surface external medium interface are considered.

HeI lambda 10830 line: a probe of the accretion/ejection activity in RU Lupi .

NASA Astrophysics Data System (ADS)

Podio, L.; Garcia, P. J. V.; Bacciotti, F.

Most of the observed lines and continuum emission excesses from Classical T Tauri Stars (CTTSs) take place at the star-disk interface or in the inner disk region. These regions have a complex emission topology still largely unknown. The HeI lambda 10830 line showed to be a powerful instrument to trace both accreting matter, in emission, and outflowing gas via the frequently detected absorption features. To fully exploit the diagnostic potential of this line we performed a spectro-astrometric analysis of the spectra of the TTS RU Lupi, taken with ISAAC at the VLT. The analysis highlighted a displacement with respect to the source of the region where the absorption feature is generated. This indicates the presence of both an inner stellar wind and a collimated micro-jet in the circumstellar region of RU Lupi.

Design of a steganographic virtual operating system

NASA Astrophysics Data System (ADS)

Ashendorf, Elan; Craver, Scott

2015-03-01

A steganographic file system is a secure file system whose very existence on a disk is concealed. Customarily, these systems hide an encrypted volume within unused disk blocks, slack space, or atop conventional encrypted volumes. These file systems are far from undetectable, however: aside from their ciphertext footprint, they require a software or driver installation whose presence can attract attention and then targeted surveillance. We describe a new steganographic operating environment that requires no visible software installation, launching instead from a concealed bootstrap program that can be extracted and invoked with a chain of common Unix commands. Our system conceals its payload within innocuous files that typically contain high-entropy data, producing a footprint that is far less conspicuous than existing methods. The system uses a local web server to provide a file system, user interface and applications through a web architecture.

Hygroscopic properties of magnetic recording tape

NASA Technical Reports Server (NTRS)

Cuddihy, E. F.

1976-01-01

Relative humidity has been recognized as an important environmental factor in many head-tape interface phenomena such as headwear, friction, staining, and tape shed. Accordingly, the relative humidity is usually specified in many applications of tape use, especially when tape recorders are enclosed in hermetically sealed cases. Normally, the relative humidity is believed regulated by humidification of the fill gas to the specification relative humidity. This study demonstrates that the internal relative humidity in a sealed case is completely controlled by the time-dpendence of the hygroscopic properties of the pack of magnetic recording tape. Differences are found in the hygroscopic properties of the same brand of tape, which apparently result from aging, and which may have an effect on the long-term humidity-regulating behavior in a sealed case, and on the occurrence of head-tape interface phenomena from the long-term use of the tape. Results are presented on the basic hygroscopic properties of magnetic tape, its humidity-regulating behavior in a sealed case, and a theoretical commentary on the relative humidity dependence of head-wear by tape, is included.

The EOSDIS software challenge

NASA Astrophysics Data System (ADS)

Jaworski, Allan

1993-08-01

The Earth Observing System (EOS) Data and Information System (EOSDIS) will serve as a major resource for the earth science community, supporting both command and control of complex instruments onboard the EOS spacecraft and the archiving, distribution, and analysis of data. The scale of EOSDIS and the volume of multidisciplinary research to be conducted using EOSDIS resources will produce unparalleled needs for technology transparency, data integration, and system interoperability. The scale of this effort far outscopes any previous scientific data system in its breadth or operational and performance needs. Modern hardware technology can meet the EOSDIS technical challenge. Multiprocessing speeds of many giga-flops are being realized by modern computers. Online storage disk, optical disk, and videocassette libraries with storage capacities of many terabytes are now commercially available. Radio frequency and fiber optics communications networks with gigabit rates are demonstrable today. It remains, of course, to perform the system engineering to establish the requirements, architectures, and designs that will implement the EOSDIS systems. Software technology, however, has not enjoyed the price/performance advances of hardware. Although we have learned to engineer hardware systems which have several orders of magnitude greater complexity and performance than those built in the 1960's, we have not made comparable progress in dramatically reducing the cost of software development. This lack of progress may significantly reduce our capabilities to achieve economically the types of highly interoperable, responsive, integraded, and productive environments which are needed by the earth science community. This paper describes some of the EOSDIS software requirements and current activities in the software community which are applicable to meeting the EOSDIS challenge. Some of these areas include intelligent user interfaces, software reuse libraries, and domain engineering. Also included are discussions of applicable standards in the areas of operating systems interfaces, user interfaces, communications interfaces, data transport, and science algorithm support, and their role in supporting the software development process.

Real-time shipboard displays for science operation and planning on CGC Healy

NASA Astrophysics Data System (ADS)

Roberts, S.; Chayes, D.; Arko, R.

2007-12-01

To facilitate effective science planning and decision making, we have developed a real-time geospatial browser and other displays widely used by many if not all members of USCGC Healy's science cruises and some officers and crew since 2004. In order to enable a 'zero-configuration' experience to the end user with nearly any modern browser, on any platform, anywhere on the ship with wired (or wireless) network access, we chose a Web-based/server-centric approach that provides a very low barrier to access in an environment where we have many participants constantly coming and going, often with their own computers. The principle interface for planning and operational decision making is a georeferenced, Web-based user interface built on the MapServer Web GIS platform developed at the University of Minnesota (http://mapserver.gis.umn.edu/), using the PostGIS spatial database extensions (http://postgis.refractions.net/) to enable live database connectivity. Data available include current ship position and orientation, historical ship tracks and data, seafloor bathymetry, station locations, RADARSAT, and subbottom profiles among others. In addition to the user interfaces that are part of individual instrumentation (such as the sonars and navigation systems), custom interfaces have been developed to centralize data with high update rates such as sea surface temperature, vessel attitude, position, etc. Underlying data acquisition and storage is provided by the Lamont Data System (LDS) and the NOAA SCS system. All data are stored on RAIDed disk systems and shared across a switched network with a gigabit fiber backbone. The real-time displays access data in a number of ways including real-time UDP datagrams from LDS, accessing files on disk, and querying a PostgreSQL relational backend. This work is supported by grants from the U.S. National Science Foundation, Office of Polar Programs, Arctic Science section.

Collisional phase shifts of ring dark solitons in inhomogeneous Bose Einstein condensates

NASA Astrophysics Data System (ADS)

Peng, Ping; Li, Guan-Qiang; Xue, Ju-Kui

2007-06-01

The head-on collisions of two ring dark solitons in inhomogeneous Bose Einstein condensates (BECs) with thin disk-shaped potential are studied by the extended Poincaré Lighthill Kuo (PLK) perturbation method. The result shows that the system admits a solution with two concentric ring solitons, one moving inwards and the other moving outwards, which in small-amplitude limit, are described by two modified cylindrical KdV equations in the respective reference frames. In particular, the analytical phase shifts induced by the head-on collisions between two ring dark solitary waves are derived, and the result shows that the phase shifts change with the radial coordinate r according to the (1+σr)r law (where σ˜ωr2/ωz2), which are quite different with the homogeneous case.

Suppression of ITI by array head reading and 2D-equalization

NASA Astrophysics Data System (ADS)

Nakamura, Y.; Suzuto, R.; Osawa, H.; Okamoto, Y.; Kanai, Y.; Muraoka, H.

2017-05-01

Two-dimensional magnetic recording (TDMR) by shingled magnetic recording (SMR) draws attention as a next generation technology to increase the recording density in hard disk drive (HDD). It is shown that the two-dimensional finite impulse response (2D-FIR) filter provides gain the reproducing waveforms from an array head with 3 readers in the TDMR under a specification of 4 Tbit/inch.2 We evaluate the effect of the intertrack interference (ITI) reduction by 2D-FIR using the correlation between the real FIR filter output and the partial response class-I (PR1) signal corresponding to recording sequence by the computer simulation. The results show that the 2D-FIR filter is effective to mitigate ITI and improves the signal-to-noise ratio at the discriminate point by about 0.6 dB.

Head-Mounted Display Technology for Low Vision Rehabilitation and Vision Enhancement

PubMed Central

Ehrlich, Joshua R.; Ojeda, Lauro V.; Wicker, Donna; Day, Sherry; Howson, Ashley; Lakshminarayanan, Vasudevan; Moroi, Sayoko E.

2017-01-01

Purpose To describe the various types of head-mounted display technology, their optical and human factors considerations, and their potential for use in low vision rehabilitation and vision enhancement. Design Expert perspective. Methods An overview of head-mounted display technology by an interdisciplinary team of experts drawing on key literature in the field. Results Head-mounted display technologies can be classified based on their display type and optical design. See-through displays such as retinal projection devices have the greatest potential for use as low vision aids. Devices vary by their relationship to the user’s eyes, field of view, illumination, resolution, color, stereopsis, effect on head motion and user interface. These optical and human factors considerations are important when selecting head-mounted displays for specific applications and patient groups. Conclusions Head-mounted display technologies may offer advantages over conventional low vision aids. Future research should compare head-mounted displays to commonly prescribed low vision aids in order to compare their effectiveness in addressing the impairments and rehabilitation goals of diverse patient populations. PMID:28048975

Finite-difference model to simulate the areal flow of saltwater and fresh water separated by an interface

USGS Publications Warehouse

Mercer, James W.; Larson, S.P.; Faust, Charles R.

1980-01-01

Model documentation is presented for a two-dimensional (areal) model capable of simulating ground-water flow of salt water and fresh water separated by an interface. The partial differential equations are integrated over the thicknesses of fresh water and salt water resulting in two equations describing the flow characteristics in the areal domain. These equations are approximated using finite-difference techniques and the resulting algebraic equations are solved for the dependent variables, fresh water head and salt water head. An iterative solution method was found to be most appropriate. The program is designed to simulate time-dependent problems such as those associated with the development of coastal aquifers, and can treat water-table conditions or confined conditions with steady-state leakage of fresh water. The program will generally be most applicable to the analysis of regional aquifer problems in which the zone between salt water and fresh water can be considered a surface (sharp interface). Example problems and a listing of the computer code are included. (USGS).

ECFS: A decentralized, distributed and fault-tolerant FUSE filesystem for the LHCb online farm

NASA Astrophysics Data System (ADS)

Rybczynski, Tomasz; Bonaccorsi, Enrico; Neufeld, Niko

2014-06-01

The LHCb experiment records millions of proton collisions every second, but only a fraction of them are useful for LHCb physics. In order to filter out the "bad events" a large farm of x86-servers (~2000 nodes) has been put in place. These servers boot from and run from NFS, however they use their local disk to temporarily store data, which cannot be processed in real-time ("data-deferring"). These events are subsequently processed, when there are no live-data coming in. The effective CPU power is thus greatly increased. This gain in CPU power depends critically on the availability of the local disks. For cost and power-reasons, mirroring (RAID-1) is not used, leading to a lot of operational headache with failing disks and disk-errors or server failures induced by faulty disks. To mitigate these problems and increase the reliability of the LHCb farm, while at same time keeping cost and power-consumption low, an extensive research and study of existing highly available and distributed file systems has been done. While many distributed file systems are providing reliability by "file replication", none of the evaluated ones supports erasure algorithms. A decentralised, distributed and fault-tolerant "write once read many" file system has been designed and implemented as a proof of concept providing fault tolerance without using expensive - in terms of disk space - file replication techniques and providing a unique namespace as a main goals. This paper describes the design and the implementation of the Erasure Codes File System (ECFS) and presents the specialised FUSE interface for Linux. Depending on the encoding algorithm ECFS will use a certain number of target directories as a backend to store the segments that compose the encoded data. When target directories are mounted via nfs/autofs - ECFS will act as a file-system over network/block-level raid over multiple servers.

Collaborative Research and Development Delivery. Order 0041: Models for the Prediction of Interfacial Properties

DTIC Science & Technology

2006-08-01

and analytical techniques. Materials with larger grains, such as gamma titanium aluminide , can be instrumented with strain gages on each grain...scale. Materials such as Ti-15-Al-33Nb(at.%) have a significantly smaller microstructure than gamma titanium aluminide , therefore strain gages can...contact fatigue problems that arise at the blade -disk interface in aircraft engines. The stress fields can be used to predict the performance of

A Multi-scale Cognitive Approach to Intrusion Detection and Response

DTIC Science & Technology

2015-12-28

the behavior of the traffic on the network, either by using mathematical formulas or by replaying packet streams. As a result, simulators depend...large scale. Summary of the most important results We obtained a powerful machine, which has 768 cores and 1.25 TB memory . RBG has been...time. Each client is configured with 1GB memory , 10 GB disk space, and one 100M Ethernet interface. The server nodes include web servers

Imaging the equilibrium state and magnetization dynamics of partially built hard disk write heads

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

Valkass, R. A. J., E-mail: rajv202@ex.ac.uk; Yu, W.; Shelford, L. R.

Four different designs of partially built hard disk write heads with a yoke comprising four repeats of NiFe (1 nm)/CoFe (50 nm) were studied by both x-ray photoemission electron microscopy (XPEEM) and time-resolved scanning Kerr microscopy (TRSKM). These techniques were used to investigate the static equilibrium domain configuration and the magnetodynamic response across the entire structure, respectively. Simulations and previous TRSKM studies have made proposals for the equilibrium domain configuration of similar structures, but no direct observation of the equilibrium state of the writers has yet been made. In this study, static XPEEM images of the equilibrium state of writer structures weremore » acquired using x-ray magnetic circular dichroism as the contrast mechanism. These images suggest that the crystalline anisotropy dominates the equilibrium state domain configuration, but competition with shape anisotropy ultimately determines the stability of the equilibrium state. Dynamic TRSKM images were acquired from nominally identical devices. These images suggest that a longer confluence region may hinder flux conduction from the yoke into the pole tip: the shorter confluence region exhibits clear flux beaming along the symmetry axis, whereas the longer confluence region causes flux to conduct along one edge of the writer. The observed variations in dynamic response agree well with the differences in the equilibrium magnetization configuration visible in the XPEEM images, confirming that minor variations in the geometric design of the writer structure can have significant effects on the process of flux beaming.« less

Small-Scale Thermal Violence Cook Off Test

NASA Astrophysics Data System (ADS)

Cook, Malcolm; Curtis, John; Stennett, Christopher

2015-06-01

The Small-Scale thermal Violence Test (SSVT) is designed to quantify the violence (explosiveness) of test materials by means of observing the velocity history of a metal burst disk that forms one end of a strong thick-walled cylindrical test vehicle. A copper heating block is placed to the rear of, but in contact with, the sample and provides sealing. The difference in thermal conductivity between copper and steel is sufficient that thermal runaway is induced near to the explosive / copper interface in an unlagged test. A series of experiments has been made, in which explosive specimens were confined and heated to explosion. A high-accuracy velocity measurement system was used to record the motion of the bursting disk. These experiments have shown that the early-time motion of the bursting disk corresponds qualitatively to the onset of thermal explosion and growth of reaction within the explosive specimens. However, the velocity history traces are more complex than had been anticipated. In particular, unexplained shoulders were observed in the Phase-Doppler Velocimeter (PDV) data. Some preliminary modelling studies have been carried out in order to shed light on the complex shapes of the projectile velocity histories.

Bottom head to shell junction assembly for a boiling water nuclear reactor

DOEpatents

Fife, Alex Blair; Ballas, Gary J.

1998-01-01

A bottom head to shell junction assembly which, in one embodiment, includes an annular forging having an integrally formed pump deck and shroud support is described. In the one embodiment, the annular forging also includes a top, cylindrical shaped end configured to be welded to one end of the pressure vessel cylindrical shell and a bottom, conical shaped end configured to be welded to the disk shaped bottom head. Reactor internal pump nozzles also are integrally formed in the annular forging. The nozzles do not include any internal or external projections. Stubs are formed in each nozzle opening to facilitate welding a pump housing to the forging. Also, an upper portion of each nozzle opening is configured to receive a portion of a diffuser coupled to a pump shaft which extends through the nozzle opening. Diffuser openings are formed in the integral pump deck to provide additional support for the pump impellers. The diffuser opening is sized so that a pump impeller can extend at least partially therethrough. The pump impeller is connected to the pump shaft which extends through the nozzle opening.

Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head

PubMed Central

Tao, Y.; Eichler, A.; Holzherr, T.; Degen, C. L.

2016-01-01

Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz−1/2, equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 106 T m−1 and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ∼10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics. PMID:27647039

Bottom head to shell junction assembly for a boiling water nuclear reactor

DOEpatents

Fife, A.B.; Ballas, G.J.

1998-02-24

A bottom head to shell junction assembly which, in one embodiment, includes an annular forging having an integrally formed pump deck and shroud support is described. In the one embodiment, the annular forging also includes a top, cylindrical shaped end configured to be welded to one end of the pressure vessel cylindrical shell and a bottom, conical shaped end configured to be welded to the disk shaped bottom head. Reactor internal pump nozzles also are integrally formed in the annular forging. The nozzles do not include any internal or external projections. Stubs are formed in each nozzle opening to facilitate welding a pump housing to the forging. Also, an upper portion of each nozzle opening is configured to receive a portion of a diffuser coupled to a pump shaft which extends through the nozzle opening. Diffuser openings are formed in the integral pump deck to provide additional support for the pump impellers. The diffuser opening is sized so that a pump impeller can extend at least partially therethrough. The pump impeller is connected to the pump shaft which extends through the nozzle opening. 5 figs.

A fictitious domain finite element method for simulations of fluid-structure interactions: The Navier-Stokes equations coupled with a moving solid

NASA Astrophysics Data System (ADS)

Court, Sébastien; Fournié, Michel

2015-05-01

The paper extends a stabilized fictitious domain finite element method initially developed for the Stokes problem to the incompressible Navier-Stokes equations coupled with a moving solid. This method presents the advantage to predict an optimal approximation of the normal stress tensor at the interface. The dynamics of the solid is governed by the Newton's laws and the interface between the fluid and the structure is materialized by a level-set which cuts the elements of the mesh. An algorithm is proposed in order to treat the time evolution of the geometry and numerical results are presented on a classical benchmark of the motion of a disk falling in a channel.

Tidal Boundary Conditions in SEAWAT

USGS Publications Warehouse

Mulligan, Ann E.; Langevin, Christian; Post, Vincent E.A.

2011-01-01

SEAWAT, a U.S. Geological Survey groundwater flow and transport code, is increasingly used to model the effects of tidal motion on coastal aquifers. Different options are available to simulate tidal boundaries but no guidelines exist nor have comparisons been made to identify the most effective approach. We test seven methods to simulate a sloping beach and a tidal flat. The ocean is represented in one of the three ways: directly using a high hydraulic conductivity (high-K) zone and indirect simulation via specified head boundaries using either the General Head Boundary (GHB) or the new Periodic Boundary Condition (PBC) package. All beach models simulate similar water fluxes across the upland boundary and across the sediment-water interface although the ratio of intertidal to subtidal flow is different at low tide. Simulating a seepage face results in larger intertidal fluxes and influences near-shore heads and salinity. Major differences in flow occur in the tidal flat simulations. Because SEAWAT does not simulate unsaturated flow the water table only rises via flow through the saturated zone. This results in delayed propagation of the rising tidal signal inland. Inundation of the tidal flat is delayed as is flow into the aquifer across the flat. This is severe in the high-K and PBC models but mild in the GHB models. Results indicate that any of the tidal boundary options are fine if the ocean-aquifer interface is steep. However, as the slope of that interface decreases, the high-K and PBC approaches perform poorly and the GHB boundary is preferable.

A pilot study comparing mouse and mouse-emulating interface devices for graphic input.

PubMed

Kanny, E M; Anson, D K

1991-01-01

Adaptive interface devices make it possible for individuals with physical disabilities to use microcomputers and thus perform many tasks that they would otherwise be unable to accomplish. Special equipment is available that purports to allow functional access to the computer for users with disabilities. As technology moves from purely keyboard applications to include graphic input, it will be necessary for assistive interface devices to support graphics as well as text entry. Headpointing systems that emulate the mouse in combination with on-screen keyboards are of particular interest to persons with severe physical impairment such as high level quadriplegia. Two such systems currently on the market are the HeadMaster and the Free Wheel. The authors have conducted a pilot study comparing graphic input speed using the mouse and two headpointing interface systems on the Macintosh computer. The study used a single subject design with six able-bodied subjects, to establish a baseline for comparison with persons with severe disabilities. Results of these preliminary data indicated that the HeadMaster was nearly as effective as the mouse and that it was superior to the Free Wheel for graphics input. This pilot study, however, demonstrated several experimental design problems that need to be addressed to make the study more robust. It also demonstrated the need to include the evaluation of text input so that the effectiveness of the interface devices with text and graphic input could be compared.

Visible and invisible displacement with dynamic visual occlusion in bottlenose dolphins (Tursiops spp).

PubMed

Johnson, Christine M; Sullivan, Jess; Buck, Cara L; Trexel, Julie; Scarpuzzi, Mike

2015-01-01

Anticipating the location of a temporarily obscured target-what Piaget (the construction of reality in the child. Basic Books, New York, 1954) called "object permanence"-is a critical skill, especially in hunters of mobile prey. Previous research with bottlenose dolphins found they could predict the location of a target that had been visibly displaced into an opaque container, but not one that was first placed in an opaque container and then invisibly displaced to another container. We tested whether, by altering the task to involve occlusion rather than containment, these animals could show more advanced object permanence skills. We projected dynamic visual displays at an underwater-viewing window and videotaped the animals' head moves while observing these displays. In Experiment 1, the animals observed a small black disk moving behind occluders that shifted in size, ultimately forming one large occluder. Nine out of ten subjects "tracked" the presumed movement of the disk behind this occluder on their first trial-and in a statistically significant number of subsequent trials-confirming their visible displacement abilities. In Experiment 2, we tested their invisible displacement abilities. The disk first disappeared behind a pair of moving occluders, which then moved behind a stationary occluder. The moving occluders then reappeared and separated, revealing that the disk was no longer behind them. The subjects subsequently looked to the correct stationary occluder on eight of their ten first trials, and in a statistically significant number of subsequent trials. Thus, by altering the stimuli to be more ecologically valid, we were able to show that the dolphins could indeed succeed at an invisible displacement task.

Intelligent fiber optic sensor for solution concentration examination

NASA Astrophysics Data System (ADS)

Borecki, Michal; Kruszewski, Jerzy

2003-09-01

This paper presents the working principles of intelligent fiber-optic intensity sensor used for solution concentration examination. The sensor head is the ending of the large core polymer optical fiber. The head works on the reflection intensity basis. The reflected signal level depends on Fresnel reflection and reflection on suspended matter when the head is submersed in solution. The sensor head is mounted on a lift. For detection purposes the signal includes head submerging, submersion, emerging and emergence is measured. This way the viscosity turbidity and refraction coefficient has an effect on measured signal. The signal forthcoming from head is processed electrically in opto-electronic interface. Then it is feed to neural network. The novelty of presented sensor is implementation of neural network that works in generalization mode. The sensor resolution depends on opto-electronic signal conversion precision and neural network learning accuracy. Therefore, the number and quality of points used for learning process is very important. The example sensor application for examination of liquid soap concentration in water is presented in the paper.

GFU-6/E 30mm Ammunition Loader for GAU-8A Gun System

DTIC Science & Technology

1975-12-01

dropped onto the conveyor (See Figure 17) and transferred to the aircraft on these elements through flexible chuting which interfaces directly with the...14. Dwell Linkage 19 15. Horizontal Conveyor - Flex Chute Interface 20 16. Element Turnaround Sprocket 21 17. Horizontal Conveyor 22 18. Load Head... conveyor element mechanism for transport to the GAU-8/A loader unit. d. The contractor shall design the automated loading system to accept unfired

Musk Oxen and Micelles

NASA Astrophysics Data System (ADS)

Hill, John W.

1996-09-01

Musk oxen behavior provides an analogy to micelle formation by amphipathic substances. Mature male musk oxen protect their young and females from wolves by forming a protective circle around them. The males stand with their tails to the inside and their heads facing outward. Amphipathic substances such as soap form micelles. The hydrophobic hydrocarbon tails of the soap are turned to the inside of the micelle and the hydrophilic carboxylate heads are on the outside at the interface with the polar water molecules.

Morphology and Mobility of the Reconstructed Basilar Joint of the Pollicized Index Finger.

PubMed

Strugarek-Lecoanet, Clotilde; Chevrollier, Jérémie; Pauchard, Nicolas; Blum, Alain; Dap, François; Dautel, Gilles

2016-09-01

To evaluate outcome and function of the reconstructed basilar thumb joint after index finger pollicization in patients presenting congenital thumb deficiency. Plain radiographs and 4-dimensional dynamic volume computed tomography scan were used to evaluate the outcome of 23 pollicizations performed on 14 children between 1996 and 2009. The mean follow-up was 8 years. Patients performed continuous movements of thumb opposition during the imaging studies. Four-dimensional scan images made it possible to visualize mobility within the reconstructed joint. In 14 cases, union occurred in the metacarpal head/metacarpal base interface. In the 9 other cases, there was a nonunion at this interface. The reconstructed joint was mobile in 20 cases, including 3 in which there was also mobility at the site of the nonunion. In 3 cases in our series, mobility was present only at the site of the nonunion, between the base and the head of the second metacarpal. Remodeling and flattening out of the metacarpal head occurred in 16 of 23 cases. The transposed metacarpal head remained spherical in 7 cases. The reconstructed joint adapts, both morphologically and functionally, allowing movement on all 3 spatial planes. Existing mechanical constraints on the reconstructed joint may explain its remodeled appearance. Therapeutic IV. Copyright © 2016 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

DPM: Future Proof Storage

NASA Astrophysics Data System (ADS)

Alvarez, Alejandro; Beche, Alexandre; Furano, Fabrizio; Hellmich, Martin; Keeble, Oliver; Rocha, Ricardo

2012-12-01

The Disk Pool Manager (DPM) is a lightweight solution for grid enabled disk storage management. Operated at more than 240 sites it has the widest distribution of all grid storage solutions in the WLCG infrastructure. It provides an easy way to manage and configure disk pools, and exposes multiple interfaces for data access (rfio, xroot, nfs, gridftp and http/dav) and control (srm). During the last year we have been working on providing stable, high performant data access to our storage system using standard protocols, while extending the storage management functionality and adapting both configuration and deployment procedures to reuse commonly used building blocks. In this contribution we cover in detail the extensive evaluation we have performed of our new HTTP/WebDAV and NFS 4.1 frontends, in terms of functionality and performance. We summarize the issues we faced and the solutions we developed to turn them into valid alternatives to the existing grid protocols - namely the additional work required to provide multi-stream transfers for high performance wide area access, support for third party copies, credential delegation or the required changes in the experiment and fabric management frameworks and tools. We describe new functionality that has been added to ease system administration, such as different filesystem weights and a faster disk drain, and new configuration and monitoring solutions based on the industry standards Puppet and Nagios. Finally, we explain some of the internal changes we had to do in the DPM architecture to better handle the additional load from the analysis use cases.

A simplified model for equilibrium and transient swelling of thermo-responsive gels.

PubMed

Drozdov, A D; deClaville Christiansen, J

2017-11-01

A simplified model is developed for the elastic response of thermo-responsive gels subjected to swelling under an arbitrary deformation with finite strains. The constitutive equations involve five adjustable parameters that are determined by fitting observations in equilibrium water uptake tests and T-jump transient tests on thin gel disks. Two scenarios for water release under heating are revealed by means of numerical simulation. When the final temperature in a T-jump test is below the volume-phase transition temperature, deswelling is characterized by smooth distribution of water molecules and small tensile stresses. When the final temperature exceeds the critical temperature, a gel disk is split into three regions (central part with a high concentration of water molecules and two domains near the boundaries with low water content) separated by sharp interfaces, whose propagation is accompanied by development of large (comparable with the elastic modulus) tensile stresses. Copyright © 2017 Elsevier Ltd. All rights reserved.

The raw disk i/o performance of compaq storage works RAID arrays under tru64 unix

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

Uselton, A C

2000-10-19

We report on the raw disk i/o performance of a set of Compaq StorageWorks RAID arrays connected to our cluster of Compaq ES40 computers via Fibre Channel. The best cumulative peak sustained data rate is l17MB/s per node for reads and 77MB/s per node for writes. This value occurs for a configuration in which a node has two Fibre Channel interfaces to a switch, which in turn has two connections to each of two Compaq StorageWorks RAID arrays. Each RAID array has two HSG80 RAID controllers controlling (together) two 5+p RAID chains. A 10% more space efficient arrangement using amore » single 1l+p RAID chain in place of the two 5+P chains is 25% slower for reads and 40% slower for writes.« less

A Comprehensive Study on Energy Efficiency and Performance of Flash-based SSD

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

Park, Seon-Yeon; Kim, Youngjae; Urgaonkar, Bhuvan

2011-01-01

Use of flash memory as a storage medium is becoming popular in diverse computing environments. However, because of differences in interface, flash memory requires a hard-disk-emulation layer, called FTL (flash translation layer). Although the FTL enables flash memory storages to replace conventional hard disks, it induces significant computational and space overhead. Despite the low power consumption of flash memory, this overhead leads to significant power consumption in an overall storage system. In this paper, we analyze the characteristics of flash-based storage devices from the viewpoint of power consumption and energy efficiency by using various methodologies. First, we utilize simulation tomore » investigate the interior operation of flash-based storage of flash-based storages. Subsequently, we measure the performance and energy efficiency of commodity flash-based SSDs by using microbenchmarks to identify the block-device level characteristics and macrobenchmarks to reveal their filesystem level characteristics.« less

Morphology of the Dentin-resin Interface yielded by Two-step Etch-and-rinse Adhesives with Different Solvents.

PubMed

Ferreira, João C; Pires, Patrícia T; de Azevedo, Álvaro F; Arantes-Oliveira, Sofia; Silva, Mário J; de Melo, Paulo R

2017-10-01

The study aimed to analyze the morphology of the dentin-resin interface yielded by two-step etch-and-rinse adhesive systems with different solvents and compositions. A total of 32 dentine disks were prepared and randomly assigned to four groups of one-bottle etch-and-rinse adhesive systems containing different solvents: group I, Adper Scotchbond-IXT™ (ethanol/water); group II, XP-Bond™ (tertiary butanol); group III, Prime and Bond NT ® (acetone); and group IV, One Coat bond® (5% water). Adhesive systems were applied onto dentin disks, which were then thermal cycled, divided into two hemi-disks (n = 16), and prepared for field-emission scanning electron microscopy to examine the dentin-resin interdiffusion zone. Microphotographs were scanned and data were processed. Data were compared with analysis of variance multivariant test after Kolmogorov-Smirnov and Shapiro-Wilk tests using Statistic Package for the Social Sciences. The adhesive layer thickness average found was group I: 45.9 ± 13.41 urn, group II: 20.6 ± 16.32 urn, group III: 17.7 ± 11.75 urn, and group IV: 50.7 ± 27.81 urn. Significant differences were found between groups I and IV and groups II and III (p < 0.000). Groups I (3.23 ± 0.53 μm) and II (3.13 ± 0.73 μm) yielded significantly thicker hybrid layers than groups III (2.53 ± 0.50 μm) and IV (1.84 ± 0.27 μm) (p < 0.003). Group III presented a less homogeneous hybrid layer, with some gaps. Tag length average was greater in groups II (111.0 ± 36.92 μm) and IV (128.9 ± 78.38 μm) than in groups I (61.5 ± 18.10 μm) and III (68.6 ± 15.84 μm) (p < 0.008). Adhesives systems with different solvents led to significant differences in the dentin-resin interface morphology. Solvents role in adhesives bond strength should be considered together with the other adhesive system components. The adhesive containing tertiary butanol, in addition, seems to originate a good-quality hybrid layer and long, entangled tags and also appears to have greater ability to originate microtags, which may indicate higher bond strength.

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives.

PubMed

Jing, Yang; Luo, Jianbin; Yang, Wenyan; Ju, Guoxian

2004-11-01

A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d31 piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the practical application to the drive products. The U-type substrate attached to each side via piezoelectric elements also was simulated by the finite-element method and practically measured by a laser Doppler vibrometer in order to testify the driving mechanics of it. The micro-actuator coupled with two piezoelectric elements featured large displacement of 0.875 microm and high-resonance frequency over 22 kHz. The novel piezoelectric micro-actuators then possess a useful compromise performance to displacement, resonance frequency, and generative force. The results reveal that the new design concept provides a valuable alternative for multilayer piezoelectric micro-actuators.

The lining of the gut in the developing rat embryo. Its relation to the hypoblast (primary endoderm) and the notochord.

PubMed

Lamers, W H; Spliet, W G; Langemeyer, R A

1987-01-01

A light microscopical study of the morphogenesis of the gut in the rat embryo was undertaken to provide a careful map of temporal changes in the topographical relations of the (definitive) endoderm, the notochord and the hypoblast (primary endoderm). The borderline between the (definitive) endoderm and the hypoblast that appears upon gastrulation defines the lateral extension of the future gut epithelium. Within this initially semiglobular disk, the foregut and hindgut originate sequentially as blind, rapidly growing pouches. Upon the turning of the embryo, the hardly growing peripheral part of the disk becomes located in the vitelline duct. Within the head process, endodermal and notochordal cells could not be separately identified. However, slightly more posteriorly notochordal cells are seen to become embedded into the endoderm of the foregut during gastrulation. This process is not seen over the hindgut and may explain why the detachment of the notochord from the (fore)gut begins caudally.

Lithologic and physicochemical properties and hydraulics of flow in and near the freshwater/saline-water transition zone, San Antonio segment of the Edwards aquifer, south-central Texas, based on water-level and borehole geophysical log data, 1999-2007

USGS Publications Warehouse

Lambert, Rebecca B.; Hunt, Andrew G.; Stanton, Gregory P.; Nyman, Michael B.

2010-01-01

The freshwater zone of the San Antonio segment of the Edwards aquifer in south-central Texas (hereinafter, the Edwards aquifer) is bounded to the south and southeast by a zone of transition from freshwater to saline water (hereinafter, the transition zone). The boundary between the two zones is the freshwater/saline-water interface (hereinafter, the interface), defined as the 1,000-milligrams per liter dissolved solids concentration threshold. This report presents the findings of a study, done by the U.S. Geological Survey in cooperation with the San Antonio Water System, to obtain lithologic properties (rock properties associated with known stratigraphic units) and physicochemical properties (fluid conductivity and temperature) and to analyze the hydraulics of flow in and near the transition zone of the Edwards aquifer on the basis of water-level and borehole geophysical log data collected from 15 monitoring wells in four transects during 1999-2007. No identifiable relation between conductivity values from geophysical logs in monitoring wells in all transects and equivalent freshwater heads in the wells at the times the logs were run is evident; and no identifiable relation between conductivity values and vertical flow in the boreholes concurrent with the times the logs were run is evident. The direction of the lateral equivalent freshwater head gradient and thus the potential lateral flow at the interface in the vicinity of the East Uvalde transect fluctuates between into and out of the freshwater zone, depending on recharge and withdrawals. Whether the prevailing direction on average is into or out of the freshwater zone is not clearly indicated. Equivalent freshwater head data do not indicate a prevailing direction of the lateral gradient at the interface in the vicinity of the Tri-County transect. The prevailing direction on average of the lateral gradient and thus potential lateral flow at the interface in the vicinity of the Kyle transect likely is from the transition zone into the freshwater zone. The hypothesis regarding the vertical gradient at the East Uvalde transect, and thus the potential for vertical flow near an interface conceptualized as a surface sloping upward in the direction of the dip of the stratigraphic units, is that the potential for vertical flow fluctuates between into and out of the freshwater zone, depending on recharge and withdrawals. At the Tri-County transect, a downward gradient on the fresh-water side of the interface and an upward gradient on the saline-water side are evidence of opposing potentials that appear to have stabilized the position of the interface over the range of hydrologic conditions that occurred at the times the logs were run. At the Fish Hatchery transect, an upward gradient on the saline-water side of the interface, coupled with the assumption of a sloping interface, implies a vertical gradient from the transition zone into the freshwater zone. This potential for vertical movement of the interface apparently was opposed by the potential (head) on the freshwater side of the interface that kept the interface relatively stable over the range of hydrologic conditions during which the logs were run. The five flow logs for Kyle transect freshwater well KY1 all indicate upward flow that originates from the Glen Rose Limestone, the uppermost unit of the Trinity aquifer; and one log for well KY2 shows upward flow entering the borehole from the Trinity aquifer. These flow data constitute evidence of the potential for flow from the Trinity aquifer into the Edwards aquifer in the vicinity of the Kyle transect. Subsurface temperature data indicate that flow on average is more active, or vigorous, on the freshwater side of the interface than on the saline-water side. A hydraulic connection between the transition zone and the freshwater zone is indicated by similar patterns in the hydrographs of the 15 transect monitoring wells in and near the transition zone and three county index wel

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

Hopwood, J.E.; Affeldt, B.

An IBM personal computer (PC), a Gerber coordinate digitizer, and a collection of other instruments make up a system known as the Coordinate Digitizer Interactive Processor (CDIP). The PC extracts coordinate data from the digitizer through a special interface, and then, after reformatting, transmits the data to a remote VAX computer, a floppy disk, and a display terminal. This system has improved the efficiency of producing printed circuit-board artwork and extended the useful life of the Gerber GCD-1 Digitizer. 1 ref., 12 figs.

Laboratory process control using natural language commands from a personal computer

NASA Technical Reports Server (NTRS)

Will, Herbert A.; Mackin, Michael A.

1989-01-01

PC software is described which provides flexible natural language process control capability with an IBM PC or compatible machine. Hardware requirements include the PC, and suitable hardware interfaces to all controlled devices. Software required includes the Microsoft Disk Operating System (MS-DOS) operating system, a PC-based FORTRAN-77 compiler, and user-written device drivers. Instructions for use of the software are given as well as a description of an application of the system.

Free-Field Spatialized Aural Cues for Synthetic Environments

DTIC Science & Technology

1994-09-01

any of the references previously listed. B. MIDI Other than electronic musicians and a few hobbyists, the Musical Instrument Digital Interface (MIDI...developed in 1983 and still has a long way to go in improving its capabilities, but the advantages are numerous. An entire musical score can be stored...the same musical file on a computer in one of the various digital sound formats could easily occupy 90 megabytes of disk space. 7 K III. PREVIOUS WORK

Initial Experience With A Prototype Storage System At The University Of North Carolina

NASA Astrophysics Data System (ADS)

Creasy, J. L.; Loendorf, D. D.; Hemminger, B. M.

1986-06-01

A prototype archiving system manufactured by the 3M Corporation has been in place at the University of North Carolina for approximately 12 months. The system was installed as a result of a collaboration between 3M and UNC, with 3M seeking testing of their system, and UNC realizing the need for an archiving system as an essential part of their PACS test-bed facilities. System hardware includes appropriate network and disk interface devices as well as media for both short and long term storage of images and their associated information. The system software includes those procedures necessary to communicate with the network interface elements(NIEs) as well as those procedures necessary to interpret the ACR-NEMA header blocks and to store the images. A subset of the total ACR-NEMA header is parsed and stored in a relational database system. The entire header is stored on disk with the completed study. Interactive programs have been developed that allow radiologists to easily retrieve information about the archived images and to send the full images to a viewing console. Initial experience with the system has consisted primarily of hardware and software debugging. Although the system is ACR-NEMA compatable, further objective and subjective assessments of system performance is awaiting the connection of compatable consoles and acquisition devices to the network.

L10 FePtCu bit patterned media

NASA Astrophysics Data System (ADS)

Brombacher, C.; Grobis, M.; Lee, J.; Fidler, J.; Eriksson, T.; Werner, T.; Hellwig, O.; Albrecht, M.

2012-01-01

Chemically ordered 5 nm-thick L10 FePtCu films with strong perpendicular magnetic anisotropy were post-patterned by nanoimprint lithography into a dot array over a 3 mm-wide circumferential band on a 3 inch Si wafer. The dots with a diameter of 30 nm and a center-to-center pitch of 60 nm appear as single domain and reveal an enhanced switching field as compared to the continuous film. We demonstrate successful recording on a single track using shingled writing with a conventional hard disk drive write/read head.

36. INTERIOR VIEW LOOKING WEST FROM UNDERNEATH THE ORE BINS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

36. INTERIOR VIEW LOOKING WEST FROM UNDERNEATH THE ORE BINS LOOKING AT THE BACK SIDE OF THE HENDY CHALLENGE CONTINUOUS ORE FEEDERS, #1 IS ON THE LEFT, #2 IS CENTER, AND #3 IS ON THE RIGHT. THESE ARE USED TO KEEP A CONTINUOUS FLOW OF ORE INTO THE STAMP MILLS. NOTE THE SPARE FEEDER DISKS ON THE FLOOR BOTTOM CENTER AND SPARE STAMP HEADS AND SHOES ON THE FLOOR BOTTOM LEFT OF THE IMAGE. - Standard Gold Mill, East of Bodie Creek, Northeast of Bodie, Bodie, Mono County, CA

Lamina cribrosa position and Bruch's membrane opening differences between anterior ischemic optic neuropathy and open-angle glaucoma.

PubMed

Rebolleda, Gema; Pérez-Sarriegui, Ane; Díez-Álvarez, Laura; De Juan, Victoria; Muñoz-Negrete, Francisco J

2018-06-01

To compare the optic nerve head morphology among primary open-angle glaucoma, non-arteritic anterior ischemic optic neuropathy eyes, their fellow healthy eyes and control eyes, using spectral-domain optical coherence tomography with enhanced depth imaging. Observational cross-sectional study including 88 eyes of 68 patients. In this study, 23 non-arteritic anterior ischemic optic neuropathy eyes, 17 fellow unaffected eyes, 25 primary open-angle glaucoma eyes, and 23 age-matched control eyes were included. Peripapillary retinal nerve fiber layer thickness and optic disk area were evaluated. Bruch's membrane opening diameter, optic cup depth, anterior lamina cribrosa depth, and prelaminar tissue thickness were assessed. Non-arteritic anterior ischemic optic neuropathy and primary open-angle glaucoma eyes had similar visual field mean deviation and peripapillary retinal nerve fiber layer thickness (P = 0.6 and P = 0.56, respectively). Bruch's membrane opening diameter was significantly larger in primary open-angle glaucoma eyes than in control eyes (P = 0.02). Lamina cribrosa and disk cup were deeper in eyes with primary open-angle glaucoma than both control and non-arteritic anterior ischemic optic neuropathy eyes (P < 0.001). Prelaminar tissue thickness was significantly thinner in primary open-angle glaucoma eyes than in non-arteritic anterior ischemic optic neuropathy eyes (P < 0.001). Lamina cribrosa was shallower in both non-arteritic anterior ischemic optic neuropathy and unaffected fellow eyes compared to healthy eyes (P < 0.001 and P = 0.04, respectively). No differences were found in the optic disk area. A forward lamina cribrosa placement and not a smaller disk could be involved in the pathogenesis of non-arteritic anterior ischemic optic neuropathy. A significantly larger Bruch's membrane opening diameter was found in primary open-angle glaucoma eyes compared with control eyes. This issue has clinical implications because Bruch's membrane opening has been considered a stable reference for disk-related measures.

A Case-Based Study with Radiologists Performing Diagnosis Tasks in Virtual Reality.

PubMed

Venson, José Eduardo; Albiero Berni, Jean Carlo; Edmilson da Silva Maia, Carlos; Marques da Silva, Ana Maria; Cordeiro d'Ornellas, Marcos; Maciel, Anderson

2017-01-01

In radiology diagnosis, medical images are most often visualized slice by slice. At the same time, the visualization based on 3D volumetric rendering of the data is considered useful and has increased its field of application. In this work, we present a case-based study with 16 medical specialists to assess the diagnostic effectiveness of a Virtual Reality interface in fracture identification over 3D volumetric reconstructions. We developed a VR volume viewer compatible with both the Oculus Rift and handheld-based head mounted displays (HMDs). We then performed user experiments to validate the approach in a diagnosis environment. In addition, we assessed the subjects' perception of the 3D reconstruction quality, ease of interaction and ergonomics, and also the users opinion on how VR applications can be useful in healthcare. Among other results, we have found a high level of effectiveness of the VR interface in identifying superficial fractures on head CTs.

Analysis of two colliding fractionally damped spherical shells in modelling blunt human head impacts

NASA Astrophysics Data System (ADS)

Rossikhin, Yury A.; Shitikova, Marina V.

2013-06-01

The collision of two elastic or viscoelastic spherical shells is investigated as a model for the dynamic response of a human head impacted by another head or by some spherical object. Determination of the impact force that is actually being transmitted to bone will require the model for the shock interaction of the impactor and human head. This model is indended to be used in simulating crash scenarios in frontal impacts, and provide an effective tool to estimate the severity of effect on the human head and to estimate brain injury risks. The model developed here suggests that after the moment of impact quasi-longitudinal and quasi-transverse shock waves are generated, which then propagate along the spherical shells. The solution behind the wave fronts is constructed with the help of the theory of discontinuities. It is assumed that the viscoelastic features of the shells are exhibited only in the contact domain, while the remaining parts retain their elastic properties. In this case, the contact spot is assumed to be a plane disk with constant radius, and the viscoelastic features of the shells are described by the fractional derivative standard linear solid model. In the case under consideration, the governing differential equations are solved analytically by the Laplace transform technique. It is shown that the fractional parameter of the fractional derivative model plays very important role, since its variation allows one to take into account the age-related changes in the mechanical properties of bone.

Virtual interface environment

NASA Technical Reports Server (NTRS)

Fisher, Scott S.

1986-01-01

A head-mounted, wide-angle, stereoscopic display system controlled by operator position, voice and gesture has been developed for use as a multipurpose interface environment. The system provides a multisensory, interactive display environment in which a user can virtually explore a 360-degree synthesized or remotely sensed environment and can viscerally interact with its components. Primary applications of the system are in telerobotics, management of large-scale integrated information systems, and human factors research. System configuration, application scenarios, and research directions are described.

Analytical solution for the transient wave propagation of a buried cylindrical P-wave line source in a semi-infinite elastic medium with a fluid surface layer

NASA Astrophysics Data System (ADS)

Shan, Zhendong; Ling, Daosheng

2018-02-01

This article develops an analytical solution for the transient wave propagation of a cylindrical P-wave line source in a semi-infinite elastic solid with a fluid layer. The analytical solution is presented in a simple closed form in which each term represents a transient physical wave. The Scholte equation is derived, through which the Scholte wave velocity can be determined. The Scholte wave is the wave that propagates along the interface between the fluid and solid. To develop the analytical solution, the wave fields in the fluid and solid are defined, their analytical solutions in the Laplace domain are derived using the boundary and interface conditions, and the solutions are then decomposed into series form according to the power series expansion method. Each item of the series solution has a clear physical meaning and represents a transient wave path. Finally, by applying Cagniard's method and the convolution theorem, the analytical solutions are transformed into the time domain. Numerical examples are provided to illustrate some interesting features in the fluid layer, the interface and the semi-infinite solid. When the P-wave velocity in the fluid is higher than that in the solid, two head waves in the solid, one head wave in the fluid and a Scholte wave at the interface are observed for the cylindrical P-wave line source.

Propagating wave in active region-loops, located over the solar disk observed by the Interface Region Imaging Spectrograph

NASA Astrophysics Data System (ADS)

Zhang, B.; Hou, Y. J.; Zhang, J.

2018-03-01

Aims: We aim to ascertain the physical parameters of a propagating wave over the solar disk detected by the Interface Region Imaging Spectrograph (IRIS). Methods: Using imaging data from the IRIS and the Solar Dynamic Observatory (SDO), we tracked bright spots to determine the parameters of a propagating transverse wave in active region (AR) loops triggered by activation of a filament. Deriving the Doppler velocity of Si IV line from spectral observations of IRIS, we have determined the rotating directions of active region loops which are relevant to the wave. Results: On 2015 December 19, a filament was located on the polarity inversion line of the NOAA AR 12470. The filament was activated and then caused a C1.1 two-ribbon flare. Between the flare ribbons, two rotation motions of a set of bright loops were observed to appear in turn with opposite directions. Following the end of the second rotation, a propagating wave and an associated transverse oscillation were detected in these bright loops. In 1400 Å channel, there was bright material flowing along the loops in a wave-like manner, with a period of 128 s and a mean amplitude of 880 km. For the transverse oscillation, we tracked a given loop and determine the transverse positions of the tracking loop in a limited longitudinal range. In both of 1400 Å and 171 Å channels, approximately four periods are distinguished during the transverse oscillation. The mean period of the oscillation is estimated as 143 s and the displacement amplitude as between 1370 km and 690 km. We interpret these oscillations as a propagating kink wave and obtain its speed of 1400 km s-1. Conclusions: Our observations reveal that a flare associated with filament activation could trigger a kink propagating wave in active region loops over the solar disk. Movies associated to Figs. 1-4 are available at http://https://www.aanda.org

Trunnionosis: Does Head Size Affect Fretting and Corrosion in Total Hip Arthroplasty?

PubMed

Del Balso, Christopher; Teeter, Matthew G; Tan, Sok Chuen; Howard, James L; Lanting, Brent A

2016-10-01

Wear and tribocorrosion at the modular head-neck taper interface may be a cause of failure in metal-on-polyethylene total hip arthroplasty (THA). The present investigation endeavored to elucidate the effect of femoral head diameter on fretting and corrosion in retrieved head-neck tapers. A retrieval analysis of THA prostheses in vivo for a minimum of 1 year was performed. Twenty-three femoral heads of 32-mm diameter were matched with 28-mm heads based on time in vivo and head length (-3 mm to +8 mm). All included implants featured a single taper design from a single manufacturer. Fretting and corrosion damage scoring was performed for each implant under stereomicroscopic visualization. Head diameter was observed to affect fretting (P = .01), with 32-mm femoral heads exhibiting greater total fretting scores than 28-mm heads. Fretting damage was greatest (P = .01) in the central concentric zone of the femoral head bore tapers, regardless of head diameter, length, or stem offset. No significant effect on total corrosion scores was observed for any head or stem variable. Retrieved implant total corrosion scores were positively correlated (ρ = 0.51, P < .001) with implantation time. Increased femoral head diameter in THA may produce greater fretting damage owing to and increased head-neck moment arm. There is no associated increase in corrosion with 28-mm and 32-mm heads of this taper design. The longer a THA prosthesis is implanted, the greater the risk of damage due to corrosion. Copyright © 2016 Elsevier Inc. All rights reserved.

Properties and Corrosion Performance of Self-reinforced Composite PEEK for Proposed Use as a Modular Taper Gasket.

PubMed

Ouellette, Eric S; Gilbert, Jeremy L

2016-11-01

Fretting corrosion in medical alloys is a persistent problem, and the need for biomaterials that can effectively suppress mechanically assisted crevice corrosion in modular taper junctions or otherwise insulate metal-on-metal interfaces in mechanically demanding environments is as yet unmet. The purpose of this study is to characterize a novel material, self-reinforced composite polyetheretherketone (SRC-PEEK) and to evaluate its ability to inhibit fretting corrosion in a pin-on-disk metal-on-metal interface test. SRC-PEEK was fabricated by hot compaction of in-house-made PEEK fibers by compacting uniaxial layups at 344°C under a load of 18,000 N for 10 minutes. SRC-PEEK, bulk isotropic PEEK, and the in-house-made PEEK fibers were analyzed for thermal transitions (T g , T m ) through differential scanning calorimetry, crystallinity, crystal size, crystalline orientation (Hermanns orientation parameter) through wide-angle x-ray scattering, and modulus, tensile strength, yield stress, and strain to failure through monotonic tensile testing. SRC-insulated pin-on-disk samples were compared with metal-on-metal control samples in pin-on-disk fretting corrosion experiments using fretting current and fretting mechanics measurements. Fifty-micron cyclic motion at 2.5 Hz was applied to the interface, first over a range of loads (0.5-35 N) while held at -0.05 V versus Ag/AgCl and then over a range of voltages (-0.5 to 0.5 V) at a constant contact stress of 73 ± 19 MPa for SRC-PEEK and 209 ± 41 MPa for metal-on-metal, which were different for each group as a result of changes in true contact area due to variations in modulus between sample groups. Pins, disks, and SRC samples were imaged for damage (on alloy and SRC surfaces) and evidence of corrosion (on alloy pin and disk surfaces). SRC specimens were analyzed for traces of alloy transferred to the surface using energy dispersive spectroscopy after pin-on-disk testing. SRC-PEEK showed improved mechanical properties to bulk PEEK (modulus = 5.0 ± 0.3 GPa, 2.8 ± 0.1 GPa, respectively, p < 0.001) and higher crystallinity to bulk PEEK (44.2% ± 3%, 39.5% ± 0.5%, respectively, p = 0.039), but had comparable crystalline orientation as compared with the initial PEEK fibers. SRC-PEEK reduced fretting currents compared with metal-on-metal controls by two to three orders of magnitude in both variable load (4.0E-5 ± 3.8E-5 μA versus 2.9E-3 ± 7.1E-4 μA, respectively, p = 0.018) and variable potential (7.5E-6 ± 4.7E-6 μA versus 5.3E-3 ± 1.4E-3 μA, respectively, p = 0.022) fretting corrosion testing. Minimal damage was observed on surfaces insulated with SRC-PEEK, whereas control surfaces showed considerable fretting corrosion damage and metal transfer. The SRC-PEEK gaskets in this study demonstrated higher crystallinity and crystalline orientation and improved monotonic tensile properties compared with bulk PEEK with the ability to effectively insulate Ti6Al4V and CoCrMo alloy surfaces and prevent the initiation of fretting corrosion under high contact-stress conditions. This novel SRC-PEEK material may offer potential as a thin film gasket material for modular tapers. Pending further in vitro and in vivo analyses, this approach may be able to preserve the advantages of modular junctions for surgeons while potentially limiting the downside risks associated with mechanically assisted crevice corrosion.

Current status of EVA degradation in Si modules and interface stability in CdTe/CdS modules

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

Czanderna, A.W.

1994-06-30

The goals, objectives, background, technical approach, status, and accomplishments on the PV Module Reliability Research Task are summarized for FY 1993. The accomplishments are reported in two elements, ethylene vinyl acetate (EVA) degradation and stability in CdTe/CdS modules. The EVA results are presented under the headings modified EVA and potential EVA replacements, degradation mechanisms, efficiency losses from yellowed EVA, and equipment acquisitions. The results on CdTe/CdS modules are presented under subheadings of stability of the SnO[sub 2]/CdS interface and degradation at the CdTe/CdS interface.

Storage resource manager

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

Perelmutov, T.; Bakken, J.; Petravick, D.

Storage Resource Managers (SRMs) are middleware components whose function is to provide dynamic space allocation and file management on shared storage components on the Grid[1,2]. SRMs support protocol negotiation and reliable replication mechanism. The SRM standard supports independent SRM implementations, allowing for a uniform access to heterogeneous storage elements. SRMs allow site-specific policies at each location. Resource Reservations made through SRMs have limited lifetimes and allow for automatic collection of unused resources thus preventing clogging of storage systems with ''orphan'' files. At Fermilab, data handling systems use the SRM management interface to the dCache Distributed Disk Cache [5,6] and themore » Enstore Tape Storage System [15] as key components to satisfy current and future user requests [4]. The SAM project offers the SRM interface for its internal caches as well.« less

Constitutive activation and uncoupling of the atrial natriuretic peptide receptor by mutations at the dimer interface. Role of the dimer structure in signalling.

PubMed

Qiu, Yue; Ogawa, Haruo; Miyagi, Masaru; Misono, Kunio S

2004-02-13

The crystal packing of the extracellular hormone binding domain of the atrial natriuretic peptide (ANP) receptor contains two possible dimer pairs, the head-to-head (hh) and tail-to-tail (tt) dimer pairs associated through the membrane-distal and membrane-proximal subdomains, respectively. The tt-dimer structure has been proposed previously (van den Akker, F., Zhang, X., Miyagi, M., Huo, X., Misono, K. S., and Yee, V. C. (2000) Nature 406, 101-104). However, no direct evidence is available to identify the physiological dimer form. Here we report site-directed mutagenesis studies of residues at the two alternative dimer interfaces in the full-length receptor expressed on COS cells. The Trp74 to Arg mutation (W74R) or D71R at the hh-dimer interface caused partial constitutive guanylate cyclase activation, whereas mutation F96D or H99D caused receptor uncoupling. In contrast, mutation Y196D or L225D at the tt-interface had no such effect. His99 modification at the hh-dimer interface by ethoxyformic anhydride abolished ANP binding. These results suggest that the hh-dimer represents the physiological structure. Recently, we determined the crystal structure of ANPR complexed with ANP and proposed a hormone-induced rotation mechanism mediating transmembrane signaling (H. Ogawa, Y. Qiu, C. M. Ogata, and K. S. Misono, submitted for publication). The observed effects of mutations are consistent with the ANP-induced structural change identified from the crystal structures with and without ANP and support the proposed rotation mechanism for ANP receptor signaling.

Tape/head interface study

NASA Technical Reports Server (NTRS)

1983-01-01

Existing high energy tapes, high track density heads, and transport guidance techniques were evaluated and characterized to enable these technologies to be employed in future spacecraft recorders with high confidence. The results of these study efforts demonstrated tracking accuracy tape and head density that will support spacecraft recorders with data rates of a minimum of 150 Mbps and storage capacities ranging from 10 to the 10th to 10 to the 11th bits. Seven high energy tapes of either .25 in width, 1.00 in width, or both, were tested. All tapes were tested at the same speed (30 ips) and the same packing density (33 KBI). The performance of all 1 in tapes was considered superior.

Rotary powder feed through apparatus

DOEpatents

Lewis, Gary K.; Less, Richard M.

2001-01-01

A device for increasing the uniformity of solids within a solids fabrication system, such as a direct light fabrication (DLF) system in which gas entrained powders are passed through the focal point of a moving high-power light which fuses the particles in the powder to a surface being built up in layers. The invention provides a feed through interface wherein gas entrained powders input from stationary input lines are coupled to a rotating head of the fabrication system. The invention eliminates the need to provide additional slack in the feed lines to accommodate head rotation, and therefore reduces feed line bending movements which induce non-uniform feeding of gas entrained powder to a rotating head.

Design and Evaluation of Shape-Changing Haptic Interfaces for Pedestrian Navigation Assistance.

PubMed

Spiers, Adam J; Dollar, Aaron M

2017-01-01

Shape-changing interfaces are a category of device capable of altering their form in order to facilitate communication of information. In this work, we present a shape-changing device that has been designed for navigation assistance. 'The Animotus' (previously, 'The Haptic Sandwich' ), resembles a cube with an articulated upper half that is able to rotate and extend (translate) relative to the bottom half, which is fixed in the user's grasp. This rotation and extension, generally felt via the user's fingers, is used to represent heading and proximity to navigational targets. The device is intended to provide an alternative to screen or audio based interfaces for visually impaired, hearing impaired, deafblind, and sighted pedestrians. The motivation and design of the haptic device is presented, followed by the results of a navigation experiment that aimed to determine the role of each device DOF, in terms of facilitating guidance. An additional device, 'The Haptic Taco', which modulated its volume in response to target proximity (negating directional feedback), was also compared. Results indicate that while the heading (rotational) DOF benefited motion efficiency, the proximity (translational) DOF benefited velocity. Combination of the two DOF improved overall performance. The volumetric Taco performed comparably to the Animotus' extension DOF.

Evolutionarily conserved morphogenetic movements at the vertebrate head-trunk interface coordinate the transport and assembly of hypopharyngeal structures.

PubMed

Lours-Calet, Corinne; Alvares, Lucia E; El-Hanfy, Amira S; Gandesha, Saniel; Walters, Esther H; Sobreira, Débora Rodrigues; Wotton, Karl R; Jorge, Erika C; Lawson, Jennifer A; Kelsey Lewis, A; Tada, Masazumi; Sharpe, Colin; Kardon, Gabrielle; Dietrich, Susanne

2014-06-15

The vertebrate head-trunk interface (occipital region) has been heavily remodelled during evolution, and its development is still poorly understood. In extant jawed vertebrates, this region provides muscle precursors for the throat and tongue (hypopharyngeal/hypobranchial/hypoglossal muscle precursors, HMP) that take a stereotype path rostrally along the pharynx and are thought to reach their target sites via active migration. Yet, this projection pattern emerged in jawless vertebrates before the evolution of migratory muscle precursors. This suggests that a so far elusive, more basic transport mechanism must have existed and may still be traceable today. Here we show for the first time that all occipital tissues participate in well-conserved cell movements. These cell movements are spearheaded by the occipital lateral mesoderm and ectoderm that split into two streams. The rostrally directed stream projects along the floor of the pharynx and reaches as far rostrally as the floor of the mandibular arch and outflow tract of the heart. Notably, this stream leads and engulfs the later emerging HMP, neural crest cells and hypoglossal nerve. When we (i) attempted to redirect hypobranchial/hypoglossal muscle precursors towards various attractants, (ii) placed non-migratory muscle precursors into the occipital environment or (iii) molecularly or (iv) genetically rendered muscle precursors non-migratory, they still followed the trajectory set by the occipital lateral mesoderm and ectoderm. Thus, we have discovered evolutionarily conserved morphogenetic movements, driven by the occipital lateral mesoderm and ectoderm, that ensure cell transport and organ assembly at the head-trunk interface. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Design of Composite Hip Prostheses Considering the Long-Term Behavior of the Femur

NASA Astrophysics Data System (ADS)

Lim, Jong Wan; Jeong, Jae Youn; Ha, Sung Kyu

A design method for the hip prosthesis is proposed which can alleviate problems associated with stress shielding, proximal loosening and the high stress of bone-implant interfaces after total hip replacement. The stress shielding which may lead to bone resorption, can cause a loosening of the stem and a fracture of femoral bone. Generally the composites were more suitable for hip prosthesis material in the long-term stability than metallic alloy because design cases of composite materials produced less stress shielding than titanium alloy. A bone remodeling algorithm was implemented in a nonlinear finite element program to predict the long-term performance of the hip prosthesis. The three neck shapes and three cross sections of composite hip were examined. It was found that the stress concentration in the distal region of the titanium stem which may cause the patient's thigh pains was reduced using composite material. The head neck shape was closely related with the cortical bone resorption and the cancellous bone apposition at proximal region whereas the cross-section was closely related with the relative micromotion between interfaces. The convex head neck type with the quadrangle cross-section produced less subsidence at proximal region on the medial side than the others. For all composite material cases, the cancellous bone apposition occurred at partial interfaces, which may result in a stable bio-fixation. The design performances of the convex neck head type with the hexagonal cross-section designed to insure the long-term stability were found to be more suitable than the others.

Molecular dynamics shows that ion pairing and counterion anchoring control the properties of triflate micelles: a comparison with triflate at the air/water interface.

PubMed

Lima, Filipe S; Chaimovich, Hernan; Cuccovia, Iolanda M; Horinek, Dominik

2014-02-11

Micellar properties of dodecyltrimethylammonium triflate (DTA-triflate, DTATf) are very different from those of DTA-bromide (DTAB). DTATf aggregates show high aggregation numbers (Nagg), low degree of counterion dissociation (α), disk-like shape, high packing, ordering, and low hydration. These micellar properties and the low surface tension of NaTf aqueous solutions point to a high affinity of Tf(-) to the micellar and air/water interfaces. Although the micellar properties of DTATf are well defined, the source of the Tf(-) effect upon the DTA aggregates is unclear. Molecular dynamics (MD) simulations of Tf(-) (and Br(-)) at the air/water interface and as counterion of a DTA aggregate were performed to clarify the nature of Tf(-) preferences for these interfaces. The effect of NaTf or NaBr on surface tension calculated from MD simulations agreed with the reported experimental values. From the MD simulations a high affinity of Tf(-) toward the interface, which occurred in a specific orientation, was calculated. The micellar properties calculated from the MD simulations for DTATf and DTAB were consistent with experimental data: in MD simulations, the DTATf aggregate was more ordered, packed, and dehydrated than the DTAB aggregate. The Tf(-)/alkyltrimethylammonium interaction energies, calculated from the MD simulations, suggested ion pair formation at the micellar interface, stabilized by the preferential orientation of the adsorbed Tf(-) at the micellar interface.

Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses.

PubMed

Witt, Florian; Gührs, Julian; Morlock, Michael M; Bishop, Nicholas E

2015-01-01

Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N) the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100%) and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%). Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm) was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface.

Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses

PubMed Central

Witt, Florian; Gührs, Julian; Morlock, Michael M.; Bishop, Nicholas E.

2015-01-01

Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N) the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100%) and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%). Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm) was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface. PMID:26280914

Biomechanical Studies on Patterns of Cranial Bone Fracture Using the Immature Porcine Model.

PubMed

Haut, Roger C; Wei, Feng

2017-02-01

This review was prepared for the American Society of Mechanical Engineers Lissner Medal. It specifically discusses research performed in the Orthopaedic Biomechanics Laboratories on pediatric cranial bone mechanics and patterns of fracture in collaboration with the Forensic Anthropology Laboratory at Michigan State University. Cranial fractures are often an important element seen by forensic anthropologists during the investigation of pediatric trauma cases litigated in courts. While forensic anthropologists and forensic biomechanists are often called on to testify in these cases, there is little basic science developed in support of their testimony. The following is a review of studies conducted in the above laboratories and supported by the National Institute of Justice to begin an understanding of the mechanics and patterns of pediatric cranial bone fracture. With the lack of human pediatric specimens, the studies utilize an immature porcine model. Because much case evidence involves cranial bone fracture, the studies described below focus on determining input loading based on the resultant bone fracture pattern. The studies involve impact to the parietal bone, the most often fractured cranial bone, and begin with experiments on entrapped heads, progressing to those involving free-falling heads. The studies involve head drops onto different types and shapes of interfaces with variations of impact energy. The studies show linear fractures initiating from sutural boundaries, away from the impact site, for flat surface impacts, in contrast to depressed fractures for more focal impacts. The results have been incorporated into a "Fracture Printing Interface (FPI)," using machine learning and pattern recognition algorithms. The interface has been used to help interpret mechanisms of injury in pediatric death cases collected from medical examiner offices. The ultimate aim of this program of study is to develop a "Human Fracture Printing Interface" that can be used by forensic investigators in determining mechanisms of pediatric cranial bone fracture.

CPP magnetoresistance of magnetic multilayers: A critical review

NASA Astrophysics Data System (ADS)

Bass, Jack

2016-06-01

We present a comprehensive, critical review of data and analysis of Giant (G) Magnetoresistance (MR) with Current-flow Perpendicular-to-the-layer-Planes (CPP-MR) of magnetic multilayers [F/N]n (n=number of repeats) composed of alternating nanoscale layers of ferromagnetic (F) and non-magnetic (N) metals, or of spin-valves that allow control of anti-parallel (AP) and parallel (P) orientations of the magnetic moments of adjacent F-layers. GMR, a large change in resistance when an applied magnetic field changes the moment ordering of adjacent F-layers from AP to P, was discovered in 1988 in the geometry with Current flow in the layer-Planes (CIP). The CPP-MR has two advantages over the CIP-MR: (1) relatively simple two-current series-resistor (2CSR) and more general Valet-Fert (VF) models allow more direct access to the underlying physics; and (2) it is usually larger, which should be advantageous for devices. When the first CPP-MR data were published in 1991, it was not clear whether electronic transport in GMR multilayers is completely diffusive or at least partly ballistic. It was not known whether the properties of layers and interfaces would vary with layer thickness or number. It was not known whether the CPP-MR would be dominated by scattering within the F-metals or at the F/N interfaces. Nothing was known about: (1) spin-flipping within F-metals, characterized by a spin-diffusion length, lsfF; (2) interface specific resistances (AR=area A times resistance R) for N1/N2 interfaces; (3) interface specific resistances and interface spin-dependent scattering asymmetry at F/N and F1/F2 interfaces; and (4) spin-flipping at F/N, F1/F2 and N1/N2 interfaces. Knowledge of spin-dependent scattering asymmetries in F-metals and F-alloys, and of spin-flipping in N-metals and N-alloys, was limited. Since 1991, CPP-MR measurements have quantified the scattering and spin-flipping parameters that determine GMR for a wide range of F- and N-metals and alloys and of F/N pairs. This review is designed to provide a history of how knowledge of CPP-MR parameters grew, to give credit for discoveries, to explain how combining theory and experiment has enabled extraction of quantitative information about these parameters, but also to make clear that progress was not always direct and to point out where disagreements still exist. To limit its length, the review considers only collinear orientations of the moments of adjacent F-layers. To aid readers looking for specific information, we have provided an extensive table of contents and a detailed summary. Together, these should help locate over 100 figures plus 17 tables that collect values of individual parameters. In 1997, CIP-MR replaced anisotropic MR (AMR) as the sensor in read heads of computer hard drives. In principle, the usually larger CPP-MR was a contender for the next generation read head sensor. But in 2003, CIP-MR was replaced by the even larger Tunneling MR (TMR), which has remained the read-head sensor ever since. However, as memory bits shrink to where the relatively large specific resistance AR of TMR gives too much noise and too large an R to impedance match as a read-head sensor, the door is again opened for CPP-MR. We will review progress in finding techniques and F-alloys and F/N pairs to enhance the CPP-MR, and will describe its present capabilities.

Dual-shank attachment design for omega seals

DOEpatents

Sattinger, Stanley S.

1978-01-01

An improved apparatus and process for attaching welded omega seal segments to reactor heads, standpipes, mechanisms, and plugs comprises a first shank in combination with a second shank to attach an omega seal at a metal-to-metal interface.

An UXor among FUors: Extinction-related Brightness Variations of the Young Eruptive Star V582 Aur

NASA Astrophysics Data System (ADS)

Ábrahám, P.; Kóspál, Á.; Kun, M.; Fehér, O.; Zsidi, G.; Acosta-Pulido, J. A.; Carnerero, M. I.; García-Álvarez, D.; Moór, A.; Cseh, B.; Hajdu, G.; Hanyecz, O.; Kelemen, J.; Kriskovics, L.; Marton, G.; Mező, Gy.; Molnár, L.; Ordasi, A.; Rodríguez-Coira, G.; Sárneczky, K.; Sódor, Á.; Szakáts, R.; Szegedi-Elek, E.; Szing, A.; Farkas-Takács, A.; Vida, K.; Vinkó, J.

2018-01-01

V582 Aur is an FU Ori-type young eruptive star in outburst since ∼1985. The eruption is currently in a relatively constant plateau phase, with photometric and spectroscopic variability superimposed. Here we will characterize the progenitor of the outbursting object, explore its environment, and analyze the temporal evolution of the eruption. We are particularly interested in the physical origin of the two deep photometric dips, one that occurred in 2012 and one that is ongoing since 2016. We collected archival photographic plates and carried out new optical, infrared, and millimeter-wave photometric and spectroscopic observations between 2010 and 2018, with a high sampling rate during the current minimum. Besides analyzing the color changes during fading, we compiled multiepoch spectral energy distributions and fitted them with a simple accretion disk model. Based on pre-outburst data and a millimeter continuum measurement, we suggest that the progenitor of the V582 Aur outburst is a low-mass T Tauri star with average properties. The mass of an unresolved circumstellar structure, probably a disk, is 0.04 M ⊙. The optical and near-infrared spectra demonstrate the presence of hydrogen and metallic lines, show the CO band head in absorption, and exhibit a variable Hα profile. The color variations strongly indicate that both the ∼1 yr long brightness dip in 2012 and the current minimum since 2016 are caused by increased extinction along the line of sight. According to our accretion disk models, the reddening changed from A V = 4.5 to 12.5 mag, while the accretion rate remained practically constant. Similarly to the models of the UXor phenomenon of intermediate- and low-mass young stars, orbiting disk structures could be responsible for the eclipses.

A microprogrammed data acquisition system for renography.

PubMed

Imperiale, C

1983-01-01

The purpose of this project was to design an efficient, low cost, and portable system for renography suitable for clinical use. The principles involved in the renographic test, and the procedures and calculations which act on the design of our system, are given. The system consists of an Apple II Plus computer equipped with 48K memory, two disk drives with diskettes of 143K each, a thermal printer with graphic capability, the Microsoft Z80 card, and an interface which is specifically designed for renographic data acquisition.

Competition Between Electromagnetic Modes in a Free-Electron Maser

DTIC Science & Technology

1994-02-28

electron perpendicular momentum familiar from gyrotron theory 111). The electron mass is me, initial electron velocity perpendicular and parallel to the...are Q Q2 of zeroth order (-1). Similarly, 48 Y tqfia IIOP --T-V I V s_*/ U- s sI J(93~+ I(*JQL4 8aq 5 Using matrix notation, we can write (i) = (C...disks were in turn electron beam welded to stainless steel flanges. While Kovar was needed to provide a good brazing interface, the mass of the material

Asymptotic Description of Damping Mistuning Effects on the Forced Response of Turbomachinery Bladed Disks

DTIC Science & Technology

2012-07-31

damping produced at friction and interface joints. For example, in the case of the turbine wheels produced for turbochargers for the automotive industry...effect of damping mistuning. The AMM can be regarded as an extension of the Fundamental Mistuning Model (FMM) [8, 9, 10] for the very frequent...blisks. presented at the ASME Turbo Expo, Vancouver, Canada, 2011, GT2011- 45611, 2011. [8] D.M. Feiner and J.H. Griffin. A fundamental model of mistuning

Combined liquid chromatography-mass spectrometry for trace analysis of pharmaceuticals

NASA Astrophysics Data System (ADS)

Schmidt, Lothar; Danigel, Harald; Jungclas, Hartmut

1982-07-01

A 252Cf-plasma desorption mass spectrometer (PDMS) for the analysis of thin layers from nonvolatile organic samples has been set up to be combined with a liquid chromatograph. A novel interface performs the direct inlet of the liquid sample through a capillary into the vacuum system of the spectrometer. Samples of drugs are periodically collected, transferred to the ion source and analysed using a rotating disk. This on-line sample preparation has been tested for three antiarrhythmic drugs using various solvents and mixtures.

Spider-web amphiphiles as artificial lipid clusters: design, synthesis, and accommodation of lipid components at the air-water interface.

PubMed

Ariga, Katsuhiko; Urakawa, Toshihiro; Michiue, Atsuo; Kikuchi, Jun-ichi

2004-08-03

As a novel category of two-dimensional lipid clusters, dendrimers having an amphiphilic structure in every unit were synthesized and labeled "spider-web amphiphiles". Amphiphilic units based on a Lys-Lys-Glu tripeptide with hydrophobic tails at the C-terminal and a polar head at the N-terminal are dendrically connected through stepwise peptide coupling. This structural design allowed us to separately introduce the polar head and hydrophobic tails. Accordingly, we demonstrated the synthesis of the spider-web amphiphile series in three combinations: acetyl head/C16 chain, acetyl head/C18 chain, and ammonium head/C16 chain. All the spider-web amphiphiles were synthesized in satisfactory yields, and characterized by 1H NMR, MALDI-TOFMS, GPC, and elemental analyses. Surface pressure (pi)-molecular area (A) isotherms showed the formation of expanded monolayers except for the C18-chain amphiphile at 10 degrees C, for which the molecular area in the condensed phase is consistent with the cross-sectional area assigned for all the alkyl chains. In all the spider-web amphiphiles, the molecular areas at a given pressure in the expanded phase increased in proportion to the number of units, indicating that alkyl chains freely fill the inner space of the dendritic core. The mixing of octadecanoic acid with the spider-web amphiphiles at the air-water interface induced condensation of the molecular area. From the molecular area analysis, the inclusion of the octadecanoic acid bears a stoichiometric characteristic; i.e., the number of captured octadecanoic acids in the spider-web amphiphile roughly agrees with the number of branching points in the spider-web amphiphile.

Human-machine interface hardware: The next decade

NASA Technical Reports Server (NTRS)

Marcus, Elizabeth A.

1991-01-01

In order to understand where human-machine interface hardware is headed, it is important to understand where we are today, how we got there, and what our goals for the future are. As computers become more capable, faster, and programs become more sophisticated, it becomes apparent that the interface hardware is the key to an exciting future in computing. How can a user interact and control a seemingly limitless array of parameters effectively? Today, the answer is most often a limitless array of controls. The link between these controls and human sensory motor capabilities does not utilize existing human capabilities to their full extent. Interface hardware for teleoperation and virtual environments is now facing a crossroad in design. Therefore, we as developers need to explore how the combination of interface hardware, human capabilities, and user experience can be blended to get the best performance today and in the future.

Conductivity of Langmuir-Blodgett films of a disk-shaped liquid-crystalline molecule-DNA complex studied by current-sensing atomic force microscopy.

PubMed

Nayak, Alpana; Suresh, K A

2008-08-01

We have studied the electrical conductivity in monolayer films of an ionic disk-shaped liquid-crystal molecule, pyridinium tethered with hexaalkoxytriphenylene (PyTp), and its complex with DNA by current-sensing atomic force microscopy (CS-AFM). The pure PyTp and PyTp-DNA complex monolayer films were first formed at the air-water interface and then transferred onto conducting substrates by the Langmuir-Blodgett (LB) technique to study the nanoscale electron transport through these films. The conductive tip of CS-AFM, the LB film, and the metal substrate form a nanoscopic metal-LB film-metal (M-LB-M) junction. We have measured the current-voltage (I-V) characteristics for the M-LB-M junction using CS-AFM and have analyzed the data quantitatively. We find that the I-V curves fit well to the Fowler-Nordheim (FN) model, suggesting electron tunneling to be a possible mechanism for electron transport in our system. Further, analysis of the I-V curves based on the FN model yields the barrier heights of PyTp-DNA complex and pure PyTp films. Electron transport studies of films of ionic disk-shaped liquid-crystal molecules and their complex with DNA are important from the point of view of their applications in organic electronics.

Conductivity of Langmuir-Blodgett films of a disk-shaped liquid-crystalline molecule-DNA complex studied by current-sensing atomic force microscopy

NASA Astrophysics Data System (ADS)

Nayak, Alpana; Suresh, K. A.

2008-08-01

We have studied the electrical conductivity in monolayer films of an ionic disk-shaped liquid-crystal molecule, pyridinium tethered with hexaalkoxytriphenylene (PyTp), and its complex with DNA by current-sensing atomic force microscopy (CS-AFM). The pure PyTp and PyTp-DNA complex monolayer films were first formed at the air-water interface and then transferred onto conducting substrates by the Langmuir-Blodgett (LB) technique to study the nanoscale electron transport through these films. The conductive tip of CS-AFM, the LB film, and the metal substrate form a nanoscopic metal-LB film-metal (M-LB-M) junction. We have measured the current-voltage (I-V) characteristics for the M-LB-M junction using CS-AFM and have analyzed the data quantitatively. We find that the I-V curves fit well to the Fowler-Nordheim (FN) model, suggesting electron tunneling to be a possible mechanism for electron transport in our system. Further, analysis of the I-V curves based on the FN model yields the barrier heights of PyTp-DNA complex and pure PyTp films. Electron transport studies of films of ionic disk-shaped liquid-crystal molecules and their complex with DNA are important from the point of view of their applications in organic electronics.

Distributed shared memory for roaming large volumes.

PubMed

Castanié, Laurent; Mion, Christophe; Cavin, Xavier; Lévy, Bruno

2006-01-01

We present a cluster-based volume rendering system for roaming very large volumes. This system allows to move a gigabyte-sized probe inside a total volume of several tens or hundreds of gigabytes in real-time. While the size of the probe is limited by the total amount of texture memory on the cluster, the size of the total data set has no theoretical limit. The cluster is used as a distributed graphics processing unit that both aggregates graphics power and graphics memory. A hardware-accelerated volume renderer runs in parallel on the cluster nodes and the final image compositing is implemented using a pipelined sort-last rendering algorithm. Meanwhile, volume bricking and volume paging allow efficient data caching. On each rendering node, a distributed hierarchical cache system implements a global software-based distributed shared memory on the cluster. In case of a cache miss, this system first checks page residency on the other cluster nodes instead of directly accessing local disks. Using two Gigabit Ethernet network interfaces per node, we accelerate data fetching by a factor of 4 compared to directly accessing local disks. The system also implements asynchronous disk access and texture loading, which makes it possible to overlap data loading, volume slicing and rendering for optimal volume roaming.

PC-based control unit for a head-mounted operating microscope for augmented-reality visualization in surgical navigation

NASA Astrophysics Data System (ADS)

Figl, Michael; Birkfellner, Wolfgang; Watzinger, Franz; Wanschitz, Felix; Hummel, Johann; Hanel, Rudolf A.; Ewers, Rolf; Bergmann, Helmar

2002-05-01

Two main concepts of Head Mounted Displays (HMD) for augmented reality (AR) visualization exist, the optical and video-see through type. Several research groups have pursued both approaches for utilizing HMDs for computer aided surgery. While the hardware requirements for a video see through HMD to achieve acceptable time delay and frame rate seem to be enormous the clinical acceptance of such a device is doubtful from a practical point of view. Starting from previous work in displaying additional computer-generated graphics in operating microscopes, we have adapted a miniature head mounted operating microscope for AR by integrating two very small computer displays. To calibrate the projection parameters of this so called Varioscope AR we have used Tsai's Algorithm for camera calibration. Connection to a surgical navigation system was performed by defining an open interface to the control unit of the Varioscope AR. The control unit consists of a standard PC with a dual head graphics adapter to render and display the desired augmentation of the scene. We connected this control unit to a computer aided surgery (CAS) system by the TCP/IP interface. In this paper we present the control unit for the HMD and its software design. We tested two different optical tracking systems, the Flashpoint (Image Guided Technologies, Boulder, CO), which provided about 10 frames per second, and the Polaris (Northern Digital, Ontario, Canada) which provided at least 30 frames per second, both with a time delay of one frame.

Ti-48Al-2Cr-2Nb Evaluated Under Fretting Conditions

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Lerch, Bradley A.; Draper, Susan L.; Raj, Sai V.

2002-01-01

Material parameters govern many of the design decisions in any engineering task. When two materials are in contact and microscopically small, relative motions (either vibratory or creeping) occur, and fretting fatigue can result. Fretting fatigue is a material response influenced by the materials in contact as well as by such variables as loading and vibratory conditions. Fretting produces fresh, clean interacting surfaces and induces adhesion, galling, and wear in the contact zone. Time, money, and materials are unnecessarily wasted when galling and wear result in excessive fretting fatigue that leads to poorly performing, unreliable mechanical systems. Fretting fatigue is a complex problem of significant interest to aircraft engine manufacturers. It can occur in a variety of engine components. Numerous approaches, depending on the component and the operating conditions, have been taken to address the fretting problems. The components of interest in this investigation were the low-pressure turbine blades and disks. The blades in this case were titanium aluminide, Ti-48Al-2Cr- 2Nb, and the disk was a nickel-base superalloy, Inconel 718 (IN 718). A concern for these airfoils is the fretting in fitted interfaces at the dovetail where the blade and disk are connected. Careful design can reduce fretting in most cases, but not completely eliminate it, because the airfoils frequently have a skewed (angled) blade-disk dovetail attachment, which leads to a complex stress state. Furthermore, the local stress state becomes more complex when the influence of the metal-metal contact and the edge of contact are considered.

Gold sputtered Blu-Ray disks as novel and cost effective sensors for surface enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Nieuwoudt, Michél. K.; Martin, Jacob W.; Oosterbeek, Reece N.; Novikova, Nina I.; Wang, Xindi; Malmström, Jenny; Williams, David E.; Simpson, M. C.

2015-03-01

Surface Enhanced Raman spectroscopy (SERS) offers sensitive and non-invasive detection of a variety of compounds as well as unparalleled information for establishing the molecular identity of both inorganic and organic compounds, not only in biological fluids but in all other aqueous and non-aqueous media. The localized hotspots produced through SERS at the solution/nanostructure interface of clustered gold or silver nano-particles enables detection levels of parts per trillion. Recent developments in advanced fabrication methods have enabled the manufacture of SERS substrates with repeatable surface nanostructures which provide reproducible quantitative analysis, historically a weakness of the SERS technique. In this paper we describe the novel use of gold sputtered Blu-Ray surfaces as SERS substrates. Blu-Ray disks provide ideal surfaces of SERS substrates with their repeatable and regular nano-gratings. We show that the unique surface features and composition of the recording surface enables the formation of gold nano-islands with nanogaps, simply through gold sputtering, and relate this to a 600 fold signal increase of the melamine Raman signal in aqueous solutions and detection to 68 ppb. Melamine is a triazine compound and appears not only as environmental contaminant in environmental groundwater but also as an adulterant in foods due to its high nitrogen content. We have shown significant SERS signal enhancements for spectra of melamine using gold-sputtered Blu-Ray disk surfaces, with reproducibility of 12%. Blu-Ray disks have a unique combination of design, surface features and composition of the recording surface which makes them ideal for preparation of SERS substrates by gold sputter-coating.

One-dimensional pressure transfer models for acoustic-electric transmission channels

NASA Astrophysics Data System (ADS)

Wilt, K. R.; Lawry, T. J.; Scarton, H. A.; Saulnier, G. J.

2015-09-01

A method for modeling piezoelectric-based ultrasonic acoustic-electric power and data transmission channels is presented. These channels employ piezoelectric disk transducers to convey signals across a series of physical layers using ultrasonic waves. This model decomposes the mechanical pathway of the signal into individual ultrasonic propagation layers which are generally independent of the layer's adjacent domains. Each layer is represented by a two-by-two traveling pressure wave transfer matrix which relates the forward and reverse pressure waves on one side of the layer to the pressure waves on the opposite face, where each face is assumed to be in contact with a domain of arbitrary reference acoustic impedance. A rigorous implementation of ultrasonic beam spreading is introduced and implemented within applicable domains. Compatible pressure-wave models for piezoelectric transducers are given, which relate the electric voltage and current interface of the transducer to the pressure waves on one mechanical interface while also allowing for passive acoustic loading of the secondary mechanical interface. It is also shown that the piezoelectric model's electrical interface is compatible with transmission line parameters (ABCD-parameters), allowing for connection of electronic components and networks. The model is shown to be capable of reproducing the behavior of realistic physical channels.

Design of optimized piezoelectric HDD-sliders

NASA Astrophysics Data System (ADS)

Nakasone, Paulo H.; Yoo, Jeonghoon; Silva, Emilio C. N.

2010-04-01

As storage data density in hard-disk drives (HDDs) increases for constant or miniaturizing sizes, precision positioning of HDD heads becomes a more relevant issue to ensure enormous amounts of data to be properly written and read. Since the traditional single-stage voice coil motor (VCM) cannot satisfy the positioning requirement of high-density tracks per inch (TPI) HDDs, dual-stage servo systems have been proposed to overcome this matter, by using VCMs to coarsely move the HDD head while piezoelectric actuators provides fine and fast positioning. Thus, the aim of this work is to apply topology optimization method (TOM) to design novel piezoelectric HDD heads, by finding optimal placement of base-plate and piezoelectric material to high precision positioning HDD heads. Topology optimization method is a structural optimization technique that combines the finite element method (FEM) with optimization algorithms. The laminated finite element employs the MITC (mixed interpolation of tensorial components) formulation to provide accurate and reliable results. The topology optimization uses a rational approximation of material properties to vary the material properties between 'void' and 'filled' portions. The design problem consists in generating optimal structures that provide maximal displacements, appropriate structural stiffness and resonance phenomena avoidance. The requirements are achieved by applying formulations to maximize displacements, minimize structural compliance and maximize resonance frequencies. This paper presents the implementation of the algorithms and show results to confirm the feasibility of this approach.

Visualization of Unsteady Computational Fluid Dynamics

NASA Technical Reports Server (NTRS)

Haimes, Robert

1997-01-01

The current compute environment that most researchers are using for the calculation of 3D unsteady Computational Fluid Dynamic (CFD) results is a super-computer class machine. The Massively Parallel Processors (MPP's) such as the 160 node IBM SP2 at NAS and clusters of workstations acting as a single MPP (like NAS's SGI Power-Challenge array and the J90 cluster) provide the required computation bandwidth for CFD calculations of transient problems. If we follow the traditional computational analysis steps for CFD (and we wish to construct an interactive visualizer) we need to be aware of the following: (1) Disk space requirements. A single snap-shot must contain at least the values (primitive variables) stored at the appropriate locations within the mesh. For most simple 3D Euler solvers that means 5 floating point words. Navier-Stokes solutions with turbulence models may contain 7 state-variables. (2) Disk speed vs. Computational speeds. The time required to read the complete solution of a saved time frame from disk is now longer than the compute time for a set number of iterations from an explicit solver. Depending, on the hardware and solver an iteration of an implicit code may also take less time than reading the solution from disk. If one examines the performance improvements in the last decade or two, it is easy to see that depending on disk performance (vs. CPU improvement) may not be the best method for enhancing interactivity. (3) Cluster and Parallel Machine I/O problems. Disk access time is much worse within current parallel machines and cluster of workstations that are acting in concert to solve a single problem. In this case we are not trying to read the volume of data, but are running the solver and the solver outputs the solution. These traditional network interfaces must be used for the file system. (4) Numerics of particle traces. Most visualization tools can work upon a single snap shot of the data but some visualization tools for transient problems require dealing with time.

Detailed chemical abundance analysis of the thick disk star cluster Gaia 1

NASA Astrophysics Data System (ADS)

Koch, Andreas; Hansen, Terese T.; Kunder, Andrea

2018-01-01

Star clusters, particularly those objects in the disk-bulge-halo interface are as yet poorly charted, despite the fact that they carry important information about the formation and the structure of the Milky Way. Here, we present a detailed chemical abundance study of the recently discovered object Gaia 1. Photometry has previously suggested it as an intermediate-age, moderately metal-rich system, although the exact values for its age and metallicity remained ambiguous in the literature. We measured detailed chemical abundances of 14 elements in four red giant members, from high-resolution (R = 25 000) spectra that firmly establish Gaia 1 as an object associated with the thick disk. The resulting mean Fe abundance is -0.62 ± 0.03(stat.)± 0.10(sys.) dex, which is more metal-poor than indicated by previous spectroscopy from the literature, but it is fully in line with values from isochrone fitting. We find that Gaia 1 is moderately enhanced in the α-elements, which allowed us to consolidate its membership with the thick disk via chemical tagging. The cluster's Fe-peak and neutron-capture elements are similar to those found across the metal-rich disks, where the latter indicate some level of s-process activity. No significant spread in iron nor in other heavy elements was detected, whereas we find evidence of light-element variations in Na, Mg, and Al. Nonetheless, the traditional Na-O and Mg-Al (anti-)correlations, typically seen in old globular clusters, are not seen in our data. This confirms that Gaia 1 is rather a massive and luminous open cluster than a low-mass globular cluster. Finally, orbital computations of the target stars bolster our chemical findings of Gaia 1's present-day membership with the thick disk, even though it remains unclear which mechanisms put it in that place. This paper includes data gathered with the 2.5 meter du Pont Telescope located at Las Campanas Observatory, Chile.Full Table 2 is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A13

Adaptive multimodal interaction in mobile augmented reality: A conceptual framework

NASA Astrophysics Data System (ADS)

Abidin, Rimaniza Zainal; Arshad, Haslina; Shukri, Saidatul A'isyah Ahmad

2017-10-01

Recently, Augmented Reality (AR) is an emerging technology in many mobile applications. Mobile AR was defined as a medium for displaying information merged with the real world environment mapped with augmented reality surrounding in a single view. There are four main types of mobile augmented reality interfaces and one of them are multimodal interfaces. Multimodal interface processes two or more combined user input modes (such as speech, pen, touch, manual gesture, gaze, and head and body movements) in a coordinated manner with multimedia system output. In multimodal interface, many frameworks have been proposed to guide the designer to develop a multimodal applications including in augmented reality environment but there has been little work reviewing the framework of adaptive multimodal interface in mobile augmented reality. The main goal of this study is to propose a conceptual framework to illustrate the adaptive multimodal interface in mobile augmented reality. We reviewed several frameworks that have been proposed in the field of multimodal interfaces, adaptive interface and augmented reality. We analyzed the components in the previous frameworks and measure which can be applied in mobile devices. Our framework can be used as a guide for designers and developer to develop a mobile AR application with an adaptive multimodal interfaces.

A new perspective on how humans assess their surroundings; derivation of head orientation and its role in ‘framing’ the environment

PubMed Central

Wilson, Gwendoline Ixia; Holton, Mark D.; Walker, James; Jones, Mark W.; Grundy, Ed; Davies, Ian M.; Clarke, David; Luckman, Adrian; Russill, Nick; Wilson, Vianney; Plummer, Rosie

2015-01-01

Understanding the way humans inform themselves about their environment is pivotal in helping explain our susceptibility to stimuli and how this modulates behaviour and movement patterns. We present a new device, the Human Interfaced Personal Observation Platform (HIPOP), which is a head-mounted (typically on a hat) unit that logs magnetometry and accelerometry data at high rates and, following appropriate calibration, can be used to determine the heading and pitch of the wearer’s head. We used this device on participants visiting a botanical garden and noted that although head pitch ranged between −80° and 60°, 25% confidence limits were restricted to an arc of about 25° with a tendency for the head to be pitched down (mean head pitch ranged between −43° and 0°). Mean rates of change of head pitch varied between −0.00187°/0.1 s and 0.00187°/0.1 s, markedly slower than rates of change of head heading which varied between −0.3141°/0.1 s and 0.01263°/0.1 s although frequency distributions of both parameters showed them to be symmetrical and monomodal. Overall, there was considerable variation in both head pitch and head heading, which highlighted the role that head orientation might play in exposing people to certain features of the environment. Thus, when used in tandem with accurate position-determining systems, the HIPOP can be used to determine how the head is orientated relative to gravity and geographic North and in relation to geographic position, presenting data on how the environment is being ‘framed’ by people in relation to environmental content. PMID:26157643

Sun sensing guidance system for high altitude aircraft

NASA Technical Reports Server (NTRS)

Reed, R. D. (Principal Investigator)

1982-01-01

A sun sensing guidance system for high altitude aircraft is described. The system is characterized by a disk shaped body mounted for rotation aboard the aircraft in exposed relation to solar radiation. The system also has a plurality of mutually isolated chambers; each chamber being characterized by an opening having a photosensor disposed therein and arranged in facing relation with the opening for receiving incident solar radiation and responsively providing a voltage output. Photosensors are connected in paired relation through a bridge circuit for providing heading error signals in response to detected imbalances in intensities of solar radiation.

Aluminizing a Ni sheet through severe plastic deformation induced by ball collisions

NASA Astrophysics Data System (ADS)

Romankov, S.; Shchetinin, I. V.; Park, Y. C.

2015-07-01

Aluminizing a Ni sheet was performed through severe plastic deformation induced by ball collisions. The Ni sheet was fixed in the center of a mechanically vibrated vial between two connected parts. The balls were loaded into the vial on both sides of the Ni disk. Al disks, which were fixed on the top and the bottom of the vial, served as the sources of Al contamination. During processing, the Ni sheet was subject to intense ball collisions. The Al fragments were transferred and alloyed to the surface of the Ni sheet by these collisions. The combined effects of deformation-induced plastic flow, mechanical intermixing, and grain refinement resulted in the formation of a dense, continuous nanostructured Al layer on the Ni surface on both sides of the sheet. The Al layer consisted of Al grains with an average size of about 40 nm. The Al layer was reinforced with nano-sized Ni flakes that were introduced from the Ni surface during processing. The local amorphization at the Ni/Al interface revealed that the bonding between Ni and Al was formed by mechanical intermixing of atomic layers at the interface. The hardness of the fabricated Al layer was 10 times that of the initial Al plate. The ball collisions destroyed the initial rolling texture of the Ni sheet and induced the formation of the mixed [1 0 0] + [1 1 1] fiber texture. The laminar rolling structure of the Ni was transformed into an ultrafine grain structure.

Space- and Ground-Based Crystal Growth Using a Baffle (CGB)

NASA Technical Reports Server (NTRS)

Ostrogorsky, A. G.; Marin, C.; Peignier, T.; Duffar, T.; Volz, M.; Jeter, L.; Luz, P.

2001-01-01

The composition of semiconductor crystals produced in space by conventional melt-growth processes (directional solidification and zone melting) is affected by minute levels of residual micro-acceleration, which causes natural convection. The residual acceleration has random magnitude, direction and frequency. Therefore, the velocity field in the melt is apriori unpredictable. As a result, the composition of the crystals grown in space can not be predicted and reproduced. The method for directional solidification with a submerged heater or a baffle was developed under NASA sponsorship. The disk-shaped baffle acts as a partition, creating a small melt zone at the solid-liquid interface. As a result, in ground based experiment the level of buoyancy-driven convection at the interface is significantly reduced. In several experiments with Te-doped GaSb, nearly diffusion controlled segregation was achieved.

Development of Standard Station Interface for Comprehensive Nuclear Test Ban Treaty Organistation Monitoring Networks

NASA Astrophysics Data System (ADS)

Dricker, I. G.; Friberg, P.; Hellman, S.

2001-12-01

Under the contract with the CTBTO, Instrumental Software Technologies Inc., (ISTI) has designed and developed a Standard Station Interface (SSI) - a set of executable programs and application programming interface libraries for acquisition, authentication, archiving and telemetry of seismic and infrasound data for stations of the CTBTO nuclear monitoring network. SSI (written in C) is fully supported under both the Solaris and Linux operating systems and will be shipped with fully documented source code. SSI consists of several interconnected modules. The Digitizer Interface Module maintains a near-real-time data flow between multiple digitizers and the SSI. The Disk Buffer Module is responsible for local data archival. The Station Key Management Module is a low-level tool for data authentication and verification of incoming signatures. The Data Transmission Module supports packetized near-real-time data transmission from the primary CTBTO stations to the designated Data Center. The AutoDRM module allows transport of seismic and infrasound signed data via electronic mail (auxiliary station mode). The Command Interface Module is used to pass the remote commands to the digitizers and other modules of SSI. A station operator has access to the state-of-health information and waveforms via an the Operator Interface Module. Modular design of SSI will allow painless extension of the software system within and outside the boundaries of CTBTO station requirements. Currently an alpha version of SSI undergoes extensive tests in the lab and onsite.

Ceph-based storage services for Run2 and beyond

NASA Astrophysics Data System (ADS)

van der Ster, Daniel C.; Lamanna, Massimo; Mascetti, Luca; Peters, Andreas J.; Rousseau, Hervé

2015-12-01

In 2013, CERN IT evaluated then deployed a petabyte-scale Ceph cluster to support OpenStack use-cases in production. With now more than a year of smooth operations, we will present our experience and tuning best-practices. Beyond the cloud storage use-cases, we have been exploring Ceph-based services to satisfy the growing storage requirements during and after Run2. First, we have developed a Ceph back-end for CASTOR, allowing this service to deploy thin disk server nodes which act as gateways to Ceph; this feature marries the strong data archival and cataloging features of CASTOR with the resilient and high performance Ceph subsystem for disk. Second, we have developed RADOSFS, a lightweight storage API which builds a POSIX-like filesystem on top of the Ceph object layer. When combined with Xrootd, RADOSFS can offer a scalable object interface compatible with our HEP data processing applications. Lastly the same object layer is being used to build a scalable and inexpensive NFS service for several user communities.

Liquid-Crystalline Collapse of Pulmonary Surfactant Monolayers

PubMed Central

Schief, William R.; Antia, Meher; Discher, Bohdana M.; Hall, Stephen B.; Vogel, Viola

2003-01-01

During exhalation, the surfactant film of lipids and proteins that coats the alveoli in the lung is compressed to high surface pressures, and can remain metastable for prolonged periods at pressures approaching 70 mN/m. Monolayers of calf lung surfactant extract (CLSE), however, collapse in vitro, during an initial compression at ∼45 mN/m. To gain information on the source of this discrepancy, we investigated how monolayers of CLSE collapse from the interface. Observations with fluorescence, Brewster angle, and light scattering microscopies show that monolayers containing CLSE, CLSE-cholesterol (20%), or binary mixtures of dipalmitoyl phosphatidylcholine(DPPC)-dihydrocholesterol all form bilayer disks that reside above the monolayer. Upon compression and expansion, lipids flow continuously from the monolayer into the disks, and vice versa. In several respects, the mode of collapse resembles the behavior of other amphiphiles that form smectic liquid-crystal phases. These findings suggest that components of surfactent films must collapse collectively rather than being squeezed out individually. PMID:12770885

A computer program for processing impedance cardiographic data: Improving accuracy through user-interactive software

NASA Technical Reports Server (NTRS)

Cowings, Patricia S.; Naifeh, Karen; Thrasher, Chet

1988-01-01

This report contains the source code and documentation for a computer program used to process impedance cardiography data. The cardiodynamic measures derived from impedance cardiography are ventricular stroke column, cardiac output, cardiac index and Heather index. The program digitizes data collected from the Minnesota Impedance Cardiograph, Electrocardiography (ECG), and respiratory cycles and then stores these data on hard disk. It computes the cardiodynamic functions using interactive graphics and stores the means and standard deviations of each 15-sec data epoch on floppy disk. This software was designed on a Digital PRO380 microcomputer and used version 2.0 of P/OS, with (minimally) a 4-channel 16-bit analog/digital (A/D) converter. Applications software is written in FORTRAN 77, and uses Digital's Pro-Tool Kit Real Time Interface Library, CORE Graphic Library, and laboratory routines. Source code can be readily modified to accommodate alternative detection, A/D conversion and interactive graphics. The object code utilizing overlays and multitasking has a maximum of 50 Kbytes.

Stochastic formation of magnetic vortex structures in asymmetric disks triggered by chaotic dynamics

DOE PAGES

Im, Mi-Young; Lee, Ki-Suk; Vogel, Andreas; ...

2014-12-17

The non-trivial spin configuration in a magnetic vortex is a prototype for fundamental studies of nanoscale spin behaviour with potential applications in magnetic information technologies. Arrays of magnetic vortices interfacing with perpendicular thin films have recently been proposed as enabler for skyrmionic structures at room temperature, which has opened exciting perspectives on practical applications of skyrmions. An important milestone for achieving not only such skyrmion materials but also general applications of magnetic vortices is a reliable control of vortex structures. However, controlling magnetic processes is hampered by stochastic behaviour, which is associated with thermal fluctuations in general. Here we showmore » that the dynamics in the initial stages of vortex formation on an ultrafast timescale plays a dominating role for the stochastic behaviour observed at steady state. Our results show that the intrinsic stochastic nature of vortex creation can be controlled by adjusting the interdisk distance in asymmetric disk arrays.« less

Improved astigmatic focus error detection method

NASA Technical Reports Server (NTRS)

Bernacki, Bruce E.

1992-01-01

All easy-to-implement focus- and track-error detection methods presently used in magneto-optical (MO) disk drives using pre-grooved media suffer from a side effect known as feedthrough. Feedthrough is the unwanted focus error signal (FES) produced when the optical head is seeking a new track, and light refracted from the pre-grooved disk produces an erroneous FES. Some focus and track-error detection methods are more resistant to feedthrough, but tend to be complicated and/or difficult to keep in alignment as a result of environmental insults. The astigmatic focus/push-pull tracking method is an elegant, easy-to-align focus- and track-error detection method. Unfortunately, it is also highly susceptible to feedthrough when astigmatism is present, with the worst effects caused by astigmatism oriented such that the tangential and sagittal foci are at 45 deg to the track direction. This disclosure outlines a method to nearly completely eliminate the worst-case form of feedthrough due to astigmatism oriented 45 deg to the track direction. Feedthrough due to other primary aberrations is not improved, but performance is identical to the unimproved astigmatic method.

Study of role of meniscus and viscous forces during liquid-mediated contacts separation

NASA Astrophysics Data System (ADS)

Dhital, Prabin

Menisci may form between two solid surfaces with the presence of an ultra-thin liquid film. When the separation operation is needed, meniscus and viscous forces contribute to an adhesion leading stiction, high friction, possibly high wear and potential failure of the contact systems, for instance microdevices, magnetic head disks and diesel fuel injectors. The situation may become more pronounced when the contacting surfaces are ultra-smooth and the normal load is small. Various design parameters, such as contact angle, initial separation height, surface tension and liquid viscosity, have been investigated during liquid-mediated contact separation. However, how the involved forces will change roles for various liquid is of interest and is necessary to be studied. In this study, meniscus and viscous forces due to water and liquid lubricants during separation of two flat surfaces are studied. Previously established mathematical model for meniscus and viscous forces during flat on flat contact separation is simulated. The effect of meniscus and viscous force on critical meniscus area at which those forces change role is studied with different liquid properties for flat on flat contact surfaces. The roles of the involved forces at various meniscus areas are analyzed. Experiments are done in concerns to studying the effect of surface roughness on contact angle. The impact of liquid properties, initial separation heights and contact angle on critical meniscus area for different liquid properties are analyzed. The study provides a fundamental understanding of the forces of the separation process and its value for the design of interfaces. The effect of surface roughness and liquid properties on contact angle are studied.

The effect of multiple layers of linens on surface interface pressure: results of a laboratory study.

PubMed

Williamson, Rachel; Lachenbruch, Charlie; Vangilder, Catherine

2013-06-01

Underpads and layers of linens are frequently placed under patients who are incontinent, have other moisture-related issues, and/or are immobile and cannot reposition independently. Many of these patients are also at risk for pressure ulcers and placed on pressure-redistribution surfaces. The purpose of this study was to measure the effects of linens and incontinence pads on interface pressure. Interface sacral pressures were measured (mm Hg) using a mannequinlike pelvic indenter that has pressure transducers integrated into the unit and is covered with a soft flesh-like elastomer. The indenter was loaded to simulate a median-weight male (80 kg/176 lb), and the testing was performed at head-of bed (HOB) angles of 0°, 30°, and 45°. Two different surfaces, a high performance low-air-loss support (LAL) surface and a standard foam support surface, were used and covered with a fitted sheet (FS) only or a combination of the FS and various incontinence pads and transfer sheets. Linen combinations typically used for relatively immobile patients (n = 4), moisture management (n = 4), and moisture management and immobility (n = 1) were tested, as was the heavy use of linens/pads (nine layers, n = 1). All combinations were tested 10 times at HOB angles of 0°, 30°, and 45°. The highest pressure observed was recorded (peak pressure). Ninety five percent (95%) confidence interval (CI) surrounding the mean of the 10 trials for each combination was calculated using the t-distribution; differences between means for all surface combinations were determined using one-way ANOVA with follow-up Fisher Hayter test. Results indicated that each incontinence pad, transfer sheet, or combination of linens significantly increased the mean peak sacral pressure when compared to a single FS on both the low-air-loss surface and the foam surface, regardless of the head-of-bed angle. The magnitude of peak sacral interface pressure increase for the LAL surface at 30° head-of-bed angle was 20% to 64% depending on the linen combination. At 30°, the foam surface showed increases 6% to 29% (P <0.0001) compared with a FS baseline. If linens were wet, peak interface sacral pressures were equivalent to or less than pressures measured on the same pads when measured dry. The presence of linens on both surface types adversely affected the pressure redistribution capabilities of the surfaces; added layers increased pressure proportionally. The effect on interface pressure from the linen layers was more pronounced on the LAL than the foam surface. The study results illustrate that significant increases in peak interface pressure occur in a laboratory setting when linen layers are added to pressure redistribution surfaces. Results also indicated wetting incontinence pads on a support surface did not significantly increase interface pressure. Although additional preclinical and clinical studies are needed to guide practice, excessive linen usage for patients on therapeutic support surfaces should be discouraged.

Dosimetric evaluation of the effect of dental implants in head and neck radiotherapy.

PubMed

Ozen, Julide; Dirican, Bahar; Oysul, Kaan; Beyzadeoglu, Murat; Ucok, Ozlem; Beydemir, Bedri

2005-06-01

The aim of the study was to examine the dose enhancement from scattered radiation at bone-dental implant interfaces during simulated head and neck radiotherapy. Four cylindrical titanium dental implants with 3 different sizes and lengths were implanted into a human mandible in 4 different positions. Ionization measurements for 6 MV X, 25 MV X, and Co-60 gamma rays were done. Thermoluminescent dosimeter (TLD 100 ) chips were used to measure radiation dose enhancement due to the scattered electrons from titanium and electronic disequilibrium at the tissue-metal interface. The results showed that for Co-60, there is a 21% maximum increase in dose to alveolar mandibular bone at the close proximity to the titanium. For 6-MV x-rays the dose enhancement increase was almost the same or slightly lower than for Co-60, while for 25-MV high-energy x-rays, dose enhancement was lower than that of others. This increase in dose enhancement fell off rapidly and became insignificant at 2 mm from the interface. Total dose that may lead to osteoradionecrosis risk of the mandible is slightly but not significantly affected by the scattered dose of the dental implants of lower jaw in the radiation field exposed to 3 different radiation beams.

A novel tribological study on DLC-coated micro-dimpled orthopedics implant interface.

PubMed

Choudhury, Dipankar; Urban, Filip; Vrbka, Martin; Hartl, Martin; Krupka, Ivan

2015-05-01

This study investigates a tribological performance of diamond like carbon (DLC) coated micro dimpled prosthesis heads against ceramic cups in a novel pendulum hip joint simulator. The simulator enables determining friction coefficient and viscous effects of a concave shaped specimen interface (conformal contact). Two types of DLC such as hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (Ta-C) and one set of micro dimple (diameter of 300µm, depth of 70µm, and pitch of 900µm) were fabricated on metallic prosthesis heads. The experiment results reveal a significant friction coefficient reduction to the 'dimpled a-C:H/ceramic' prosthesis compared to a 'Metal (CoCr)/ceramic' prosthesis because of their improved material and surface properties and viscous effect. The post-experiment surface analysis displays that the dimpled a-C:H yielded a minor change in the surface roughness, and generated a larger sizes of wear debris (40-200nm sized, equivalent diameter), a size which could be certainly stored in the dimple, thus likely to reducing their possible third body abrasive wear rate. Thus, dimpled a:C-H can be used as a 'metal on ceramic hip joint interface', whereas the simulator can be utilized as an advanced bio-tribometer. Copyright © 2015 Elsevier Ltd. All rights reserved.

Interfaces for Advanced Computing.

ERIC Educational Resources Information Center

Foley, James D.

1987-01-01

Discusses the coming generation of supercomputers that will have the power to make elaborate "artificial realities" that facilitate user-computer communication. Illustrates these technological advancements with examples of the use of head-mounted monitors which are connected to position and orientation sensors, and gloves that track finger and…

Using the rear projection of the Socibot Desktop robot for creation of applications with facial expressions

NASA Astrophysics Data System (ADS)

Gîlcă, G.; Bîzdoacă, N. G.; Diaconu, I.

2016-08-01

This article aims to implement some practical applications using the Socibot Desktop social robot. We mean to realize three applications: creating a speech sequence using the Kiosk menu of the browser interface, creating a program in the Virtual Robot browser interface and making a new guise to be loaded into the robot's memory in order to be projected onto it face. The first application is actually created in the Compose submenu that contains 5 file categories: audio, eyes, face, head, mood, this being helpful in the creation of the projected sequence. The second application is more complex, the completed program containing: audio files, speeches (can be created in over 20 languages), head movements, the robot's facial parameters function of each action units (AUs) of the facial muscles, its expressions and its line of sight. Last application aims to change the robot's appearance with the guise created by us. The guise was created in Adobe Photoshop and then loaded into the robot's memory.

Classification of Porcine Cranial Fracture Patterns Using a Fracture Printing Interface,^.

PubMed

Wei, Feng; Bucak, Serhat Selçuk; Vollner, Jennifer M; Fenton, Todd W; Jain, Anil K; Haut, Roger C

2017-01-01

Distinguishing between accidental and abusive head trauma in children can be difficult, as there is a lack of baseline data for pediatric cranial fracture patterns. A porcine head model has recently been developed and utilized in a series of studies to investigate the effects of impact energy level, surface type, and constraint condition on cranial fracture patterns. In the current study, an automated pattern recognition method, or a fracture printing interface (FPI), was developed to classify cranial fracture patterns that were associated with different impact scenarios documented in previous experiments. The FPI accurately predicted the energy level when the impact surface type was rigid. Additionally, the FPI was exceedingly successful in determining fractures caused by skulls being dropped with a high-level energy (97% accuracy). The FPI, currently developed on the porcine data, may in the future be transformed to the task of cranial fracture pattern classification for human infant skulls. © 2016 American Academy of Forensic Sciences.

Structure and strength at the bonding interface of a titanium-segmented polyurethane composite through 3-(trimethoxysilyl) propyl methacrylate for artificial organs.

PubMed

Sakamoto, Harumi; Doi, Hisashi; Kobayashi, Equo; Yoneyama, Takayuki; Suzuki, Yoshiaki; Hanawa, Takao

2007-07-01

The objective of this study was to investigate the structure and strength at the bonding interface of a titanium (Ti)-segmented polyurethane (SPU) composite through (3-trimethoxysilyl) propyl methacrylate (gamma-MPS) for artificial organs. The effects of the thickness of the gamma-MPS layer on the shear bonding strength between Ti and SPU were investigated. Ti disks were immersed in various concentrations of gamma-MPS solutions for several immersion times. The depth profiles of elements and the thickness of the gamma-MPS layer were determined by glow discharge optical emission spectroscopy and ellipsometry, respectively. The bonding stress at the Ti/gamma-MPS/SPU interface was evaluated with a shear bonding test. Furthermore, the fractured surface of a Ti-SPU composite was observed by optical microscopy and characterized using X-ray photoelectron spectroscopy. Consequently, the thickness of the gamma-MPS layer was controlled by the concentration of the gamma-MPS solution and immersion time. The shear bonding stress at the interface increased with the increase of the thickness of the gamma-MPS layer. Therefore, the control of the thickness of the gamma-MPS layer is significant to increase the shear bonding stress at the Ti/gamma-MPS/SPU interface. These results are significant to create composites for artificial organs consisting of other metals and polymers. Copyright 2007 Wiley Periodicals, Inc.

Enhancing the Gaming Experience Using 3D Spatial User Interface Technologies.

PubMed

Kulshreshth, Arun; Pfeil, Kevin; LaViola, Joseph J

2017-01-01

Three-dimensional (3D) spatial user interface technologies have the potential to make games more immersive and engaging and thus provide a better user experience. Although technologies such as stereoscopic 3D display, head tracking, and gesture-based control are available for games, it is still unclear how their use affects gameplay and if there are any user performance benefits. The authors have conducted several experiments on these technologies in game environments to understand how they affect gameplay and how we can use them to optimize the gameplay experience.

A novel dentin bond strength measurement technique using a composite disk in diametral compression.

PubMed

Huang, Shih-Hao; Lin, Lian-Shan; Rudney, Joel; Jones, Rob; Aparicio, Conrado; Lin, Chun-Pin; Fok, Alex

2012-04-01

New methods are needed that can predict the clinical failure of dental restorations that primarily rely on dentin bonding. Existing methods have shortcomings, e.g. severe deviation in the actual stress distribution from theory and a large standard deviation in the measured bond strength. We introduce here a novel test specimen by examining an endodontic model for dentin bonding. Specifically, we evaluated the feasibility of using the modified Brazilian disk test to measure the post-dentin interfacial bond strength. Four groups of resin composite disks which contained a slice of dentin with or without an intracanal post in the center were tested under diametral compression until fracture. Advanced nondestructive examination and imaging techniques in the form of acoustic emission (AE) and digital image correlation (DIC) were used innovatively to capture the fracture process in real time. DIC showed strain concentration first appearing at one of the lateral sides of the post-dentin interface. The appearance of the interfacial strain concentration also coincided with the first AE signal detected. Utilizing both the experimental data and finite-element analysis, the bond/tensile strengths were calculated to be: 11.2 MPa (fiber posts), 12.9 MPa (metal posts), 8.9 MPa (direct resin fillings) and 82.6 MPa for dentin. We have thus established the feasibility of using the composite disk in diametral compression to measure the bond strength between intracanal posts and dentin. The new method has the advantages of simpler specimen preparation, no premature failure, more consistent failure mode and smaller variations in the calculated bond strength. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Morphology and kinetics of crystals growth in amorphous films of Cr2O3, deposited by laser ablation

NASA Astrophysics Data System (ADS)

Bagmut, Aleksandr

2018-06-01

An electron microscopic investigation was performed on the structure and kinetics of the crystallization of amorphous Cr2O3 films, deposited by pulsed laser sputtering of chromium target in an oxygen atmosphere. The crystallization was initiated by the action of an electron beam on an amorphous film in the column of a transmission electron microscope. The kinetic curves were plotted on the basis of a frame-by-frame analysis of the video recorded during the crystallization of the film. It was found that the amorphous phase - crystal phase transition in Cr2O3 films occurs as a layer polymorphic crystallization and is characterized by the values of the dimensionless relative length unit δ0 ≈ 2000-3100. The action of the electron beam initiates the formation of crystals of two basic morphological forms: disk-shaped and sickle-shaped. Growth of a disk-shaped crystals is characterized by a constant rate v and the quadratic dependence of the fraction of the crystalline phase x on the time t. Sickle-shaped crystal at an initial stage, as it grows, becomes as ring-shaped and disk-shaped crystal. The growth of a sickle-shaped crystal is characterized by normal and tangential velocity components, which depend on the time as ∼√t and as ∼1/√t respectively The end point of the arc at the interface between the amorphous and crystalline phases as the crystal grows describes a curve, which is similar to the Fermat helix. For sickle-shaped, as well as for disk-shaped crystals, the degree of crystallinity x ∼ t2.

The distinct optic disk and peripapillary appearance in Donnai-Barrow syndrome.

PubMed

Khan, Arif O; Ghazi, Nicola G

2018-06-01

Biallelic mutations in low-density lipoprotein-related protein 2 (LRP2) cause the multi-system Donnai-Barrow syndrome (facio-oculo-acoustico-renal syndrome). Although Donnai-Barrow syndrome is recognized as a form of vitreo-retinopathy, the ocular phenotype has not been well defined. The purpose of this study is to document the disk and peripapillary appearance in Donnai-Barrow syndrome. Retrospective cases series (five children with low vision from a consanguineous Emirati family known to harbor LRP2 mutation (NM_004525.2: c.7564T>C; p.Y42522H)). All five children had high myopia (spherical equivalent from -15 to -22). One had an ophthalmic phenotypic pathognomonic for Knobloch syndrome, and genetic testing confirmed a homozygous novel COL18A1 mutation (NM_130455.3: c.2978_2987del; p.Pro993Leufs*35) with heterozygosity for the LRP2 mutation. The other four children, confirmed to be homozygous for the LRP2 mutation, had hypertelorism and down-slanting palpebral fissures. Three had spontaneous retinal detachment (two bilateral and one unilateral) with complicated post-surgical courses following retinal detachment repair. The three eyes (two children) without retinal detachment had a consistent unique optic nerve head appearance, with thin emanating vessels and multiple rings of depigmentation that made it difficult to discern the edge of the apparently small and recessed neuroretinal rim. This distinct appearance was also present in the post-surgical eyes which were not phthisical and seemed present in the single published posterior pole image found during literature review. A distinctive optic nerve head dysgenesis is part of Donnai-Barrow syndrome and can help distinguish its ocular phenotype from other vitreo-retinopathies associated with high myopia.

Antiparallel pinned NiO spin valve sensor for GMR head application (invited)

NASA Astrophysics Data System (ADS)

Pinarbasi, M.; Metin, S.; Gill, H.; Parker, M.; Gurney, B.; Carey, M.; Tsang, C.

2000-05-01

NiO antiferromagnetic material possesses certain advantages for spin valve applications and has attracted considerable attention. Some of the key advantages are its insulating properties, very high corrosion resistance, less sensitivity to composition, and its low reset temperature. This material, however, has a low blocking temperature which prevents its application to simple spin valve designs. The use of this material in spin valve structures required significant improvements in thermal stability, blocking temperature, and the spin valve design. In the present study, the blocking temperature and the blocking temperature distribution of the NiO films have been improved by depositing the films reactively using ion beam sputtering. A number of improvements in the processing method and deposition system had to be made to allow full NiO spin valve deposition for mass production. Another critical part was the use of antiparallel pinned design in place of the simple design to improve the thermal stability of the NiO spin valves as read elements at disk drive temperatures. The selection of the ferromagnetic pinned layers and the Ru spacer thickness in AP-pinned spin valves has significant impact on the behavior of the devices. These spin valves are all bottom type, NiO/PL1/Ru/PL2/Cu/Co/NiFe/Ta, where the metallic portion of the spin valve is deposited on top of the NiO AF layer. The PL1 and PL2 are ferromagnetic layers comprising NiFe and Co layers. Read elements have been made using these spin valves that delivered areal densities of 12 Gbit/in. These topics and other improvements which resulted in successful use of NiO spin valves as GMR heads in hard disk drives will be discussed.

The influence of corneal astigmatism on retinal nerve fiber layer thickness and optic nerve head parameter measurements by spectral-domain optical coherence tomography.

PubMed

Liu, Lin; Zou, Jun; Huang, Hui; Yang, Jian-guo; Chen, Shao-rong

2012-05-23

To evaluate the influence of corneal astigmatism (CA) on retinal nerve fiber layer (RNFL) thickness and optic nerve head(ONH) parameters measured with spectral-domain optical coherence tomography (OCT) in high myopes patients before refractive surgery. Seventy eyes of 35 consecutive refractive surgery candidates were included in this study. The mean age of the subjects was 26.42 ± 6.95 years, the average CA was -1.17 diopters (D; SD 0.64; range -0.2 to-3.3D), All subjects in this study were WTR CA. 34 eyes were in the normal CA group with a mean CA was -0.67 ± 0.28D, 36 eyes were in the high CA group with an average CA of -1.65 ± 0.49D. All subjects underwent ophthalmic examination and imaging with the Cirrus HD OCT. No significant difference was noted in the average cup-to-disk ratio, vertical cup-to-disk ratio and cup volume (all P values > 0.05). Compared with the normal CA group, the high CA group had a larger disc area and rim area, thinner RNFL thickness in the temporal quadrant, and the superotemporal and inferotemporal peaks were farther to the temporal horizon (All P values < 0.05). There were no significant differences between the two groups in global average RNFL thickness, as well as superior, nasal and inferior quadrant RNFL thickness (all P values > 0.05). The degree of with-the-rule CA should be considered when interpreting ONH parameters and peripapillary RNFL thickness measured by the Cirrus HD OCT. The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1148475676881895.

A personal computer-based, multitasking data acquisition system

NASA Technical Reports Server (NTRS)

Bailey, Steven A.

1990-01-01

A multitasking, data acquisition system was written to simultaneously collect meteorological radar and telemetry data from two sources. This system is based on the personal computer architecture. Data is collected via two asynchronous serial ports and is deposited to disk. The system is written in both the C programming language and assembler. It consists of three parts: a multitasking kernel for data collection, a shell with pull down windows as user interface, and a graphics processor for editing data and creating coded messages. An explanation of both system principles and program structure is presented.

Product Operations Status Summary Metrics

NASA Technical Reports Server (NTRS)

Takagi, Atsuya; Toole, Nicholas

2010-01-01

The Product Operations Status Summary Metrics (POSSUM) computer program provides a readable view into the state of the Phoenix Operations Product Generation Subsystem (OPGS) data pipeline. POSSUM provides a user interface that can search the data store, collect product metadata, and display the results in an easily-readable layout. It was designed with flexibility in mind for support in future missions. Flexibility over various data store hierarchies is provided through the disk-searching facilities of Marsviewer. This is a proven program that has been in operational use since the first day of the Phoenix mission.

Impaction Force Influences Taper-Trunnion Stability in Total Hip Arthroplasty.

PubMed

Danoff, Jonathan R; Longaray, Jason; Rajaravivarma, Raga; Gopalakrishnan, Ananthkrishnan; Chen, Antonia F; Hozack, William J

2018-07-01

This study investigated the influence of femoral head impaction force, number of head strikes, the energy sequence of head strikes, and head offset on the strength of the taper-trunnion junction. Thirty titanium-alloy trunnions were mated with 36-mm zero-offset cobalt-chromium femoral heads of corresponding taper angle. A drop tower impacted the head with 2.5J or 8.25J, resulting in 6 kN or 14 kN impaction force, respectively, in a single strike or combinations of 6 kN + 14 kN or 14 kN + 14 kN. In addition, ten 36-mm heads with -5 and +5 offset were impacted with sequential 14 kN + 14 kN strikes. Heads were subsequently disassembled using a screw-driven mechanical testing frame, and peak distraction force was recorded. Femoral head pull-off force was 45% the strike force, and heads struck with a single 14 kN impact showed a pull-off force twice that of the 6 kN group. Two head strikes with the same force did not improve pull-off force for either 6 kN (P = .90) or 14 kN (P = .90). If the forces of the 2 impactions varied, but either impact measured 14 kN, a 51% higher pull-off force was found compared to impactions of either 6 kN or 6 kN + 6 kN. Femoral head offset did not significantly change the pull-off force among -5, 0, and +5 heads (P = .37). Femoral head impaction force influenced femoral head trunnion-taper stability, whereas offset did not affect pull-off force. Multiple head strikes did not add additional stability, as long as a single strike achieved 14 kN force at the mallet-head impactor interface. Insufficient impaction force may lead to inadequate engagement of the trunnion-taper junction. Copyright © 2018 Elsevier Inc. All rights reserved.

The Effect of Molybdenum Substrate Oxidation on Molybdenum Splat Formation

NASA Astrophysics Data System (ADS)

Wang, Jun; Li, Chang-Jiu

2018-01-01

Disk splats are usually observed when the deposition temperature exceeds the transition temperature, whereas thick oxide layer will reduce the adhesion resulting from high deposition temperature. In present study, single molybdenum splats were deposited onto polished molybdenum substrates with different preheating processes to clarify the effect of surface oxidation on the splat formation. Three substrate samples experienced three different preheating processes in an argon atmosphere. Two samples were preheated to 350 and 550 °C, and another sample was cooled to 350 °C after it was preheated to 550 °C. The chemistry and compositions of substrate surface were examined by XPS. The cross sections of splats were prepared by focus ion beam (FIB) and then characterized by SEM. Nearly disk-shaped splat with small fingers in the periphery was observed on the sample preheated to 350 °C. A perfect disk-shape splat was deposited at 550 °C. With the sample on the substrate preheated to 350 °C (cooling down from 550 °C), flower-shaped splat exhibited a central core and discrete periphery detached by some voids. The results of peeling off splats by carbon tape and the morphology of FIB sampled cross sections indicated that no effective bonding formed at the splat-substrate interface for the substrate ever heated to 550 °C, due to the increasing content of MoO3 on the preheated molybdenum surface.

Experiments in teleoperator and autonomous control of space robotic vehicles

NASA Technical Reports Server (NTRS)

Alexander, Harold L.

1990-01-01

A research program and strategy are described which include fundamental teleoperation issues and autonomous-control issues of sensing and navigation for satellite robots. The program consists of developing interfaces for visual operation and studying the consequences of interface designs as well as developing navigation and control technologies based on visual interaction. A space-robot-vehicle simulator is under development for use in virtual-environment teleoperation experiments and neutral-buoyancy investigations. These technologies can be utilized in a study of visual interfaces to address tradeoffs between head-tracking and manual remote cameras, panel-mounted and helmet-mounted displays, and stereoscopic and monoscopic display systems. The present program can provide significant data for the development of control experiments for autonomously controlled satellite robots.

On continuous and discontinuous approaches for modeling groundwater flow in heterogeneous media using the Numerical Manifold Method: Model development and comparison

NASA Astrophysics Data System (ADS)

Hu, Mengsu; Wang, Yuan; Rutqvist, Jonny

2015-06-01

One major challenge in modeling groundwater flow within heterogeneous geological media is that of modeling arbitrarily oriented or intersected boundaries and inner material interfaces. The Numerical Manifold Method (NMM) has recently emerged as a promising method for such modeling, in its ability to handle boundaries, its flexibility in constructing physical cover functions (continuous or with gradient jump), its meshing efficiency with a fixed mathematical mesh (covers), its convenience for enhancing approximation precision, and its integration precision, achieved by simplex integration. In this paper, we report on developing and comparing two new approaches for boundary constraints using the NMM, namely a continuous approach with jump functions and a discontinuous approach with Lagrange multipliers. In the discontinuous Lagrange multiplier method (LMM), the material interfaces are regarded as discontinuities which divide mathematical covers into different physical covers. We define and derive stringent forms of Lagrange multipliers to link the divided physical covers, thus satisfying the continuity requirement of the refraction law. In the continuous Jump Function Method (JFM), the material interfaces are regarded as inner interfaces contained within physical covers. We briefly define jump terms to represent the discontinuity of the head gradient across an interface to satisfy the refraction law. We then make a theoretical comparison between the two approaches in terms of global degrees of freedom, treatment of multiple material interfaces, treatment of small area, treatment of moving interfaces, the feasibility of coupling with mechanical analysis and applicability to other numerical methods. The newly derived boundary-constraint approaches are coded into a NMM model for groundwater flow analysis, and tested for precision and efficiency on different simulation examples. We first test the LMM for a Dirichlet boundary and then test both LMM and JFM for an idealized heterogeneous model, comparing the numerical results with analytical solutions. Then we test both approaches for a heterogeneous model and compare the results of hydraulic head and specific discharge. We show that both approaches are suitable for modeling material boundaries, considering high accuracy for the boundary constraints, the capability to deal with arbitrarily oriented or complexly intersected boundaries, and their efficiency using a fixed mathematical mesh.

Fusion interfaces for tactical environments: An application of virtual reality technology

NASA Technical Reports Server (NTRS)

Haas, Michael W.

1994-01-01

The term Fusion Interface is defined as a class of interface which integrally incorporates both virtual and nonvirtual concepts and devices across the visual, auditory, and haptic sensory modalities. A fusion interface is a multisensory virtually-augmented synthetic environment. A new facility has been developed within the Human Engineering Division of the Armstrong Laboratory dedicated to exploratory development of fusion interface concepts. This new facility, the Fusion Interfaces for Tactical Environments (FITE) Facility is a specialized flight simulator enabling efficient concept development through rapid prototyping and direct experience of new fusion concepts. The FITE Facility also supports evaluation of fusion concepts by operation fighter pilots in an air combat environment. The facility is utilized by a multidisciplinary design team composed of human factors engineers, electronics engineers, computer scientists, experimental psychologists, and oeprational pilots. The FITE computational architecture is composed of twenty-five 80486-based microcomputers operating in real-time. The microcomputers generate out-the-window visuals, in-cockpit and head-mounted visuals, localized auditory presentations, haptic displays on the stick and rudder pedals, as well as executing weapons models, aerodynamic models, and threat models.

Isolation and characterization of Listeria monocytogenes from the black-headed gull feces in Kunming, China.

PubMed

Cao, Xiaolong; Wang, Yi; Wang, Yan; Ye, Changyun

Listeria monocytogenes is among the most important foodborne pathogens, which can be isolated from bird feces. The aim of this study was to examine the prevalence, genotypes, virulence factors and drug-resistance characteristics of L. monocytogenes isolated from the black-headed gull in Kunming, China. Serotypes and virulence genes were identified by polymerase chain reaction. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) methods were used to describe the genetic characteristics of all positive isolates. Furthermore, all L. monocytogenes isolates were tested for antimicrobial susceptibility by disk diffusion method. All isolates were positive for inlA, inlB, plcB, prfA, iap, actA and hly genes. Serotyping showed the isolates belonged to serotype 1/2b (2/9, 22%), 1/2c (3/9, 33%), and 4a (4/9, 44%). PFGE showed 4 different pulsotypes (PTs), and MLST differentiated the 9 isolates into 4 sequence types (STs), ST3 (1), ST5 (1), ST35 (3) and ST201 (4). The result of antimicrobial susceptibility revealed that all isolates were naturally sensitive to most antibiotics. The L. monocytogenes isolates had pathogenic potential. There is a potential infection risk for people who come to frequent contact with black-headed gulls in Kunming. Hence, it is necessary to conduct surveillance of L. monocytogenes in the migratory black-headed gulls, which would be valuable to prevent listeriosis in local residents and tourists. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Large-scale recrystallization of the S-layer of Bacillus coagulans E38-66 at the air/water interface and on lipid films.

PubMed Central

Pum, D; Weinhandl, M; Hödl, C; Sleytr, U B

1993-01-01

S-layer protein isolated from Bacillus coagulans E38-66 could be recrystallized into large-scale coherent monolayers at an air/water interface and on phospholipid films spread on a Langmuir-Blodgett trough. Because of the asymmetry in the physiochemical surface properties of the S-layer protein, the subunits were associated with their more hydrophobic outer face with the air/water interface and oriented with their negatively charged inner face to the zwitterionic head groups of the dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylethanolamine (DPPE) monolayer films. The dynamic crystal growth at both types of interfaces was first initiated at several distant nucleation points. The individual monocrystalline areas grew isotropically in all directions until the front edge of neighboring crystals was met. The recrystallized S-layer protein and the S-layer-DPPE layer could be chemically cross-linked from the subphase with glutaraldehyde. Images PMID:8478338

A Conserving Discretization for the Free Boundary in a Two-Dimensional Stefan Problem

NASA Astrophysics Data System (ADS)

Segal, Guus; Vuik, Kees; Vermolen, Fred

1998-03-01

The dissolution of a disk-likeAl2Cuparticle is considered. A characteristic property is that initially the particle has a nonsmooth boundary. The mathematical model of this dissolution process contains a description of the particle interface, of which the position varies in time. Such a model is called a Stefan problem. It is impossible to obtain an analytical solution for a general two-dimensional Stefan problem, so we use the finite element method to solve this problem numerically. First, we apply a classical moving mesh method. Computations show that after some time steps the predicted particle interface becomes very unrealistic. Therefore, we derive a new method for the displacement of the free boundary based on the balance of atoms. This method leads to good results, also, for nonsmooth boundaries. Some numerical experiments are given for the dissolution of anAl2Cuparticle in anAl-Cualloy.

Surface spectators and their role in relationships between activity and selectivity of the oxygen reduction reaction in acid environments.

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

Ciapina, Eduardo G.; Lopes, Pietro P.; Subbaraman, Ram

2015-11-01

We use the rotating ring disk (RRDE) method to study activity-selectivity relationships for the oxygen reduction reaction (ORR) on Pt(111) modified by various surface coverages of adsorbed CNad (ΘCNad). The results demonstrate that small variations in ΘCNad have dramatic effect on the ORR activity and peroxide production, resulting in “volcano-like” dependence with an optimal surface coverage of ΘCNad = 0.3 ML. These relationships can be simply explained by balancing electronic and ensemble effects of co-adsorbed CNad and adsorbed spectator species from the supporting electrolytes, without the need for intermediate adsorption energy arguments. Although this study has focused on the Pt(111)-CNad/H2SO4more » interface, the results and insight gained here are invaluable for controlling another dimension in the properties of electrochemical interfaces.« less

Implementing Artificial Intelligence Behaviors in a Virtual World

NASA Technical Reports Server (NTRS)

Krisler, Brian; Thome, Michael

2012-01-01

In this paper, we will present a look at the current state of the art in human-computer interface technologies, including intelligent interactive agents, natural speech interaction and gestural based interfaces. We describe our use of these technologies to implement a cost effective, immersive experience on a public region in Second Life. We provision our Artificial Agents as a German Shepherd Dog avatar with an external rules engine controlling the behavior and movement. To interact with the avatar, we implemented a natural language and gesture system allowing the human avatars to use speech and physical gestures rather than interacting via a keyboard and mouse. The result is a system that allows multiple humans to interact naturally with AI avatars by playing games such as fetch with a flying disk and even practicing obedience exercises using voice and gesture, a natural seeming day in the park.

Workflow efficiency of two 1.5 T MR scanners with and without an automated user interface for head examinations.

PubMed

Moenninghoff, Christoph; Umutlu, Lale; Kloeters, Christian; Ringelstein, Adrian; Ladd, Mark E; Sombetzki, Antje; Lauenstein, Thomas C; Forsting, Michael; Schlamann, Marc

2013-06-01

Workflow efficiency and workload of radiological technologists (RTs) were compared in head examinations performed with two 1.5 T magnetic resonance (MR) scanners equipped with or without an automated user interface called "day optimizing throughput" (Dot) workflow engine. Thirty-four patients with known intracranial pathology were examined with a 1.5 T MR scanner with Dot workflow engine (Siemens MAGNETOM Aera) and with a 1.5 T MR scanner with conventional user interface (Siemens MAGNETOM Avanto) using four standardized examination protocols. The elapsed time for all necessary work steps, which were performed by 11 RTs within the total examination time, was compared for each examination at both MR scanners. The RTs evaluated the user-friendliness of both scanners by a questionnaire. Normality of distribution was checked for all continuous variables by use of the Shapiro-Wilk test. Normally distributed variables were analyzed by Student's paired t-test, otherwise Wilcoxon signed-rank test was used to compare means. Total examination time of MR examinations performed with Dot engine was reduced from 24:53 to 20:01 minutes (P < .001) and the necessary RT intervention decreased by 61% (P < .001). The Dot engine's automated choice of MR protocols was significantly better assessed by the RTs than the conventional user interface (P = .001). According to this preliminary study, the Dot workflow engine is a time-saving user assistance software, which decreases the RTs' effort significantly and may help to automate neuroradiological examinations for a higher workflow efficiency. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

Protons at the speed of sound: Predicting specific biological signaling from physics.

PubMed

Fichtl, Bernhard; Shrivastava, Shamit; Schneider, Matthias F

2016-05-24

Local changes in pH are known to significantly alter the state and activity of proteins and enzymes. pH variations induced by pulses propagating along soft interfaces (e.g. membranes) would therefore constitute an important pillar towards a physical mechanism of biological signaling. Here we investigate the pH-induced physical perturbation of a lipid interface and the physicochemical nature of the subsequent acoustic propagation. Pulses are stimulated by local acidification and propagate - in analogy to sound - at velocities controlled by the interface's compressibility. With transient local pH changes of 0.6 directly observed at the interface and velocities up to 1.4 m/s this represents hitherto the fastest protonic communication observed. Furthermore simultaneously propagating mechanical and electrical changes in the lipid interface are detected, exposing the thermodynamic nature of these pulses. Finally, these pulses are excitable only beyond a threshold for protonation, determined by the pKa of the lipid head groups. This protonation-transition plus the existence of an enzymatic pH-optimum offer a physical basis for intra- and intercellular signaling via sound waves at interfaces, where not molecular structure and mechano-enyzmatic couplings, but interface thermodynamics and thermodynamic transitions are the origin of the observations.

Medical devices of the head, neck, and spine.

PubMed

Hunter, Tim B; Yoshino, Mark T; Dzioba, Robert B; Light, Rick A; Berger, William G

2004-01-01

There are many medical devices used for head, neck, and spinal diseases and injuries, and new devices are constantly being introduced. Many of the newest devices are variations on a previous theme. Knowing the specific name of a device is not important. It is important to recognize the presence of a device and to have an understanding of its function as well as to be able to recognize the complications associated with its use. The article discusses the most common and important devices of the head, neck, and spine, including cerebrospinal fluid shunts and the Codman Hakim programmable valve; subdural drainage catheters, subdural electrodes, intracranial electrodes, deep brain stimulators, and cerebellar electrodes; coils, balloons, adhesives, particles, and aneurysm clips; radiation therapy catheters, intracranial balloons for drug installation, and carmustine wafers; hearing aids, cochlear implants, and ossicular reconstruction prostheses; orbital prostheses, intraocular silicone oil, and lacrimal duct stents; anterior and posterior cervical plates, posterior cervical spine wiring, odontoid fracture fixation devices, cervical collars and halo vests; thoracic and lumbar spine implants, anterior and posterior instrumentation for the thoracic and lumbar spine, vertebroplasty, and artificial disks; spinal column stimulators, bone stimulators, intrathecal drug delivery pumps, and sacral stimulators; dental and facial implant devices; gastric and tracheal tubes; vagus nerve stimulators; lumboperitoneal shunts; and temperature- and oxygen-sensing probes. Copyright RSNA, 2004

Estimation of the depth to the fresh-water/salt-water interface from vertical head gradients in wells in coastal and island aquifers

NASA Astrophysics Data System (ADS)

Izuka, Scot K.; Gingerich, Stephen B.

An accurate estimate of the depth to the theoretical interface between fresh, water and salt water is critical to estimates of well yields in coastal and island aquifers. The Ghyben-Herzberg relation, which is commonly used to estimate interface depth, can greatly underestimate or overestimate the fresh-water thickness, because it assumes no vertical head gradients and no vertical flow. Estimation of the interface depth needs to consider the vertical head gradients and aquifer anisotropy that may be present. This paper presents a method to calculate vertical head gradients using water-level measurements made during drilling of a partially penetrating well; the gradient is then used to estimate interface depth. Application of the method to a numerically simulated fresh-water/salt-water system shows that the method is most accurate when the gradient is measured in a deeply penetrating well. Even using a shallow well, the method more accurately estimates the interface position than does the Ghyben-Herzberg relation where substantial vertical head gradients exist. Application of the method to field data shows that drilling, collection methods of water-level data, and aquifer inhomogeneities can cause difficulties, but the effects of these difficulties can be minimized. Résumé Une estimation précise de la profondeur de l'interface théorique entre l'eau douce et l'eau salée est un élément critique dans les estimations de rendement des puits dans les aquifères insulaires et littoraux. La relation de Ghyben-Herzberg, qui est habituellement utilisée pour estimer la profondeur de cette interface, peut fortement sous-estimer ou surestimer l'épaisseur de l'eau douce, parce qu'elle suppose l'absence de gradient vertical de charge et d'écoulement vertical. L'estimation de la profondeur de l'interface requiert de prendre en considération les gradients verticaux de charge et l'éventuelle anisotropie de l'aquifère. Cet article propose une méthode de calcul des gradients verticaux de charge à partir des mesures de niveau piézométrique faites en cours de foration d'un puits incomplet; le gradient est alors utilisé pour estimer la profondeur de l'interface. L'application de cette méthode à un système eau douce - eau salée simulé numériquement montre que la méthode est la plus précise lorsque le gradient est mesuré dans un puits pénétrant profondément dans l'aquifère. Même en utilisant un puits peu profond, la méthode estime la position de l'interface avec plus de précision que ne le fait la relation de Ghyben-Herzberg lorsqu'il existe un gradient vertical de charge bien marqué. L'application de la méthode à des données de terrain montre que la foration, les méthodes de mesure de niveau et les hétérogénéités au sein de l'aquifère peuvent être la cause de difficultés, mais que les effets de ces difficultés peuvent être réduits. Resumen Para la estimación de la productividad de pozos en acuíferos costeros y en islas es necesaria una estimación precisa de la profundidad de la interfaz teórica entre agua dulce y agua salada. La relación de Ghyben-Herzberg, usada habitualmente para estimar la profundidad de la interfaz, puede subestimar o sobrestimar el espesor de agua dulce, al asumir la ausencia de flujos y gradientes verticales. La estimación de la profundidad de la interfaz debe considerar tanto estos gradientes verticales, como la posible anisotropía del acuífero. En este artículo se presenta un método para calcular los gradientes verticales de niveles a partir de las medidas obtenidas durante la perforación de un pozo parcialmente penetrante para, a partir de este gradiente, estimar la profundidad de la interfaz. La aplicación del método a un sistema de agua dulce/agua salada simulado numéricamente muestra que el método es más preciso cuando el gradiente se mide en un pozo profundo. Incluso en el caso de un pozo superficial, el método permite una estimación más precisa de la profundidad de la interfaz que la aplicación de la fórmula de Ghyben-Herzberg, en los casos en los que existen gradientes verticales significativos. La aplicación del método a datos reales muestra que la perforación, la recogida de datos de niveles y la heterogeneidad en el acuífero pueden causar dificultades en la aplicación del método, pero que estas pueden minimizarse.

Effect of an adhesive resin luting agent on the dowel-head retention of three different core materials.

PubMed

Aksoy, Gokhan; Cotert, H Serdar; Korkut, Levent

2005-05-01

A dowel-and-core restoration may fail due to failure at either the dowel-tooth or dowel head-core material interface. Long-term clinical success of a dowel-and-core restoration depends on retention of both the dowel to the tooth and the dowel head to the core material. Thus, strengthening of the dowel head-core interface is important. This study evaluated the retention between a prefabricated dowel and 3 different core materials with or without a dual-polymerized adhesive resin luting agent. Sixty prefabricated dowels (Gold Plated Anchorage Post) were divided into 3 groups (n=20) consisting of 1 of 3 core materials, amalgam (Standalloy F), light-polymerized resin composite (Clearfil Ray), or glass ionomer (Chelon-Silver). Each core group was divided into 2 subgroups (n=10), and a dual-polymerized adhesive resin luting agent (Panavia F) was applied to the dowel heads of 1 of these subgroups before application of the core material. The manufacturing procedure was standardized by using a plastic index (4.5-mm internal diameter and 5-mm height) and a custom-made dowel holder, which held the dowel head. Prepared specimens were stored in water at room temperature for 3 months and then loaded to fracture in a universal testing machine with a crosshead speed of 0.05 mm/min until failure. Bond strengths were recorded (MPa). Data were analyzed with 2-way analysis of variance (ANOVA) in a 2 x 3 factorial randomized design (alpha=.05). Afterward, core material differences were computed with 1-way ANOVA for both of the bonded and nonbonded groups. Post hoc multiple comparisons were made with the Dunnett C multiple range test. Dowel-head retention values (MPa) of the tested core materials (mean +/- SD) from the highest to the lowest were as follows: bonded amalgam core, 296.1 +/- 108; bonded composite core, 284.3 +/- 38.3; nonbonded composite core, 177.0 +/- 53.7; nonbonded amalgam core, 128.5 +/- 35.0; bonded glass-ionomer core (GIC), 128.0 +/- 24.5; nonbonded GIC, 61.8 +/- 13.3. Two-way ANOVA revealed significant differences between the core material groups and between the bonded and nonbonded groups (P <.001). The interaction between the core material and bond variables was also significant (P =.018). One-way ANOVA revealed statistically significant differences between the bonded (P <.001) and also between the nonbonded core material groups (P <.001). Post hoc multiple comparisons showed that the dowel-head retention of the GIC was significantly weaker than the post-head retention for amalgam and resin composite, whether bonded or not. Within the limitations of this study, the adhesive resin luting agent tested appeared to have a significant strengthening effect on the dowel-head retention of the core materials.

Characterization of the fretting corrosion behavior, surface and debris from head-taper interface of two different modular hip prostheses.

PubMed

Dos Santos, Claudio T; Barbosa, Cassio; Monteiro, Maurício J; Abud, Ibrahim C; Caminha, Ieda M V; Roesler, Carlos R M

2016-09-01

Modular hip prostheses are flexible to match anatomical variations and to optimize mechanical and tribological properties of each part by using different materials. However, micromotions associated with the modular components can lead to fretting corrosion and, consequently, to release of debris which can cause adverse local tissue reactions in human body. In the present study, the surface damage and residues released during in vitro fretting corrosion tests were characterized by stereomicroscope, SEM and EDS. Two models of modular hip prosthesis were studied: Model SS/Ti Cementless whose stem was made of ASTM F136 Ti-6Al-4V alloy and whose metallic head was made of ASTM F138 austenitic stainless steel, and Model SS/SS Cemented with both components made of ASTM F138 stainless steel. The fretting corrosion tests were evaluated according to the criteria of ASTM F1875 standard. Micromotions during the test caused mechanical wear and material loss in the head-taper interface, resulting in fretting-corrosion. Model SS/SS showed higher grade of corrosion. Different morphologies of debris predominated in each model studied. Small and agglomerated particles were observed in the Model SS/Ti and irregular particles in the Model SS/SS. After 10 million cycles, the Model SS/Ti was more resistant to fretting corrosion than the Model SS/SS. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Ear and Hearing in Bipes biporus

PubMed Central

Wever, Ernest Glen; Gans, Carl

1972-01-01

The sound conduction system of Bipes biporus is unusual among amphisbaenians, in that the columella does not have a catilaginous or bony extra-columella passing laterally to the labial skin. Instead, the terminal disk of the columella ends in fibrous tissue beneath a deep fold of skin forming the nuchal constriction. The occurrence of an epihyal supports earlier suggestions that the amphisbaenian extracolumella may be homologous to the epihyal. Measurements of cochlear potentials, made by direction of the sound stimuli to the region of the head posteroventral to the quadrate bone, show that Bipes biporus ranks high among amphisbaenians in auditory sensitivity. Images PMID:4506791

Central Satellite Data Repository Supporting Research and Development

NASA Astrophysics Data System (ADS)

Han, W.; Brust, J.

2015-12-01

Near real-time satellite data is critical to many research and development activities of atmosphere, land, and ocean processes. Acquiring and managing huge volumes of satellite data without (or with less) latency in an organization is always a challenge in the big data age. An organization level data repository is a practical solution to meeting this challenge. The STAR (Center for Satellite Applications and Research of NOAA) Central Data Repository (SCDR) is a scalable, stable, and reliable repository to acquire, manipulate, and disseminate various types of satellite data in an effective and efficient manner. SCDR collects more than 200 data products, which are commonly used by multiple groups in STAR, from NOAA, GOES, Metop, Suomi NPP, Sentinel, Himawari, and other satellites. The processes of acquisition, recording, retrieval, organization, and dissemination are performed in parallel. Multiple data access interfaces, like FTP, FTPS, HTTP, HTTPS, and RESTful, are supported in the SCDR to obtain satellite data from their providers through high speed internet. The original satellite data in various raster formats can be parsed in the respective adapter to retrieve data information. The data information is ingested to the corresponding partitioned tables in the central database. All files are distributed equally on the Network File System (NFS) disks to balance the disk load. SCDR provides consistent interfaces (including Perl utility, portal, and RESTful Web service) to locate files of interest easily and quickly and access them directly by over 200 compute servers via NFS. SCDR greatly improves collection and integration of near real-time satellite data, addresses satellite data requirements of scientists and researchers, and facilitates their primary research and development activities.

Parallel Wavefront Analysis for a 4D Interferometer

NASA Technical Reports Server (NTRS)

Rao, Shanti R.

2011-01-01

This software provides a programming interface for automating data collection with a PhaseCam interferometer from 4D Technology, and distributing the image-processing algorithm across a cluster of general-purpose computers. Multiple instances of 4Sight (4D Technology s proprietary software) run on a networked cluster of computers. Each connects to a single server (the controller) and waits for instructions. The controller directs the interferometer to several images, then assigns each image to a different computer for processing. When the image processing is finished, the server directs one of the computers to collate and combine the processed images, saving the resulting measurement in a file on a disk. The available software captures approximately 100 images and analyzes them immediately. This software separates the capture and analysis processes, so that analysis can be done at a different time and faster by running the algorithm in parallel across several processors. The PhaseCam family of interferometers can measure an optical system in milliseconds, but it takes many seconds to process the data so that it is usable. In characterizing an adaptive optics system, like the next generation of astronomical observatories, thousands of measurements are required, and the processing time quickly becomes excessive. A programming interface distributes data processing for a PhaseCam interferometer across a Windows computing cluster. A scriptable controller program coordinates data acquisition from the interferometer, storage on networked hard disks, and parallel processing. Idle time of the interferometer is minimized. This architecture is implemented in Python and JavaScript, and may be altered to fit a customer s needs.

Implementation of relational data base management systems on micro-computers

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

Huang, C.L.

1982-01-01

This dissertation describes an implementation of a Relational Data Base Management System on a microcomputer. A specific floppy disk based hardward called TERAK is being used, and high level query interface which is similar to a subset of the SEQUEL language is provided. The system contains sub-systems such as I/O, file management, virtual memory management, query system, B-tree management, scanner, command interpreter, expression compiler, garbage collection, linked list manipulation, disk space management, etc. The software has been implemented to fulfill the following goals: (1) it is highly modularized. (2) The system is physically segmented into 16 logically independent, overlayable segments,more » in a way such that a minimal amount of memory is needed at execution time. (3) Virtual memory system is simulated that provides the system with seemingly unlimited memory space. (4) A language translator is applied to recognize user requests in the query language. The code generation of this translator generates compact code for the execution of UPDATE, DELETE, and QUERY commands. (5) A complete set of basic functions needed for on-line data base manipulations is provided through the use of a friendly query interface. (6) To eliminate the dependency on the environment (both software and hardware) as much as possible, so that it would be easy to transplant the system to other computers. (7) To simulate each relation as a sequential file. It is intended to be a highly efficient, single user system suited to be used by small or medium sized organizations for, say, administrative purposes. Experiments show that quite satisfying results have indeed been achieved.« less

Three-dimensional finite element modeling of pericellular matrix and cell mechanics in the nucleus pulposus of the intervertebral disk based on in situ morphology.

PubMed

Cao, Li; Guilak, Farshid; Setton, Lori A

2011-02-01

Nucleus pulposus (NP) cells of the intervertebral disk (IVD) have unique morphological characteristics and biologic responses to mechanical stimuli that may regulate maintenance and health of the IVD. NP cells reside as single cell, paired or multiple cells in a contiguous pericellular matrix (PCM), whose structure and properties may significantly influence cell and extracellular matrix mechanics. In this study, a computational model was developed to predict the stress-strain, fluid pressure and flow fields for cells and their surrounding PCM in the NP using three-dimensional (3D) finite element models based on the in situ morphology of cell-PCM regions of the mature rat NP, measured using confocal microscopy. Three-dimensional geometries of the extracellular matrix and representative cell-matrix units were used to construct 3D finite element models of the structures as isotropic and biphasic materials. In response to compressive strain of the extracellular matrix, NP cells and PCM regions were predicted to experience volumetric strains that were 1.9-3.7 and 1.4-2.1 times greater than the extracellular matrix, respectively. Volumetric and deviatoric strain concentrations were generally found at the cell/PCM interface, while von Mises stress concentrations were associated with the PCM/extracellular matrix interface. Cell-matrix units containing greater cell numbers were associated with higher peak cell strains and lower rates of fluid pressurization upon loading. These studies provide new model predictions for micromechanics of NP cells that can contribute to an understanding of mechanotransduction in the IVD and its changes with aging and degeneration.

Estimating the Intended Sound Direction of the User: Toward an Auditory Brain-Computer Interface Using Out-of-Head Sound Localization

PubMed Central

Nambu, Isao; Ebisawa, Masashi; Kogure, Masumi; Yano, Shohei; Hokari, Haruhide; Wada, Yasuhiro

2013-01-01

The auditory Brain-Computer Interface (BCI) using electroencephalograms (EEG) is a subject of intensive study. As a cue, auditory BCIs can deal with many of the characteristics of stimuli such as tone, pitch, and voices. Spatial information on auditory stimuli also provides useful information for a BCI. However, in a portable system, virtual auditory stimuli have to be presented spatially through earphones or headphones, instead of loudspeakers. We investigated the possibility of an auditory BCI using the out-of-head sound localization technique, which enables us to present virtual auditory stimuli to users from any direction, through earphones. The feasibility of a BCI using this technique was evaluated in an EEG oddball experiment and offline analysis. A virtual auditory stimulus was presented to the subject from one of six directions. Using a support vector machine, we were able to classify whether the subject attended the direction of a presented stimulus from EEG signals. The mean accuracy across subjects was 70.0% in the single-trial classification. When we used trial-averaged EEG signals as inputs to the classifier, the mean accuracy across seven subjects reached 89.5% (for 10-trial averaging). Further analysis showed that the P300 event-related potential responses from 200 to 500 ms in central and posterior regions of the brain contributed to the classification. In comparison with the results obtained from a loudspeaker experiment, we confirmed that stimulus presentation by out-of-head sound localization achieved similar event-related potential responses and classification performances. These results suggest that out-of-head sound localization enables us to provide a high-performance and loudspeaker-less portable BCI system. PMID:23437338

Ultrasound melted polymer sleeve for improved screw anchorage in trabecular bone--A novel screw augmentation technique.

PubMed

Schmoelz, W; Mayr, R; Schlottig, F; Ivanovic, N; Hörmann, R; Goldhahn, J

2016-03-01

Screw anchorage in osteoporotic bone is still limited and makes treatment of osteoporotic fractures challenging for surgeons. Conventional screws fail in poor bone quality due to loosening at the screw-bone interface. A new technology should help to improve this interface. In a novel constant amelioration process technique, a polymer sleeve is melted by ultrasound in the predrilled screw hole prior to screw insertion. The purpose of this study was to investigate in vitro the effect of the constant amelioration process platform technology on primary screw anchorage. Fresh frozen femoral heads (n=6) and vertebrae (n=6) were used to measure the maximum screw insertion torque of reference and constant amelioration process augmented screws. Specimens were cut in cranio-caudal direction, and the screws (reference and constant amelioration process) were implanted in predrilled holes in the trabecular structure on both sides of the cross section. This allowed the pairwise comparison of insertion torque for constant amelioration process and reference screws (femoral heads n=18, vertebrae n=12). Prior to screw insertion, a micro-CT scan was made to ensure comparable bone quality at the screw placement location. The mean insertion torque for the constant amelioration process augmented screws in both, the femoral heads (44.2 Ncm, SD 14.7) and the vertebral bodies (13.5 Ncm, SD 6.3) was significantly higher than for the reference screws of the femoral heads (31.7 Ncm, SD 9.6, p<0.001) and the vertebral bodies (7.1 Ncm, SD 4.5, p<0.001). The interconnection of the melted polymer sleeve with the surrounding trabecular bone in the constant amelioration process technique resulted in a higher screw insertion torque and can improve screw anchorage in osteoporotic trabecular bone. Copyright © 2016 Elsevier Ltd. All rights reserved.

MODFLOW–LGR—Documentation of ghost node local grid refinement (LGR2) for multiple areas and the boundary flow and head (BFH2) package

USGS Publications Warehouse

Mehl, Steffen W.; Hill, Mary C.

2013-01-01

This report documents the addition of ghost node Local Grid Refinement (LGR2) to MODFLOW-2005, the U.S. Geological Survey modular, transient, three-dimensional, finite-difference groundwater flow model. LGR2 provides the capability to simulate groundwater flow using multiple block-shaped higher-resolution local grids (a child model) within a coarser-grid parent model. LGR2 accomplishes this by iteratively coupling separate MODFLOW-2005 models such that heads and fluxes are balanced across the grid-refinement interface boundary. LGR2 can be used in two-and three-dimensional, steady-state and transient simulations and for simulations of confined and unconfined groundwater systems. Traditional one-way coupled telescopic mesh refinement methods can have large, often undetected, inconsistencies in heads and fluxes across the interface between two model grids. The iteratively coupled ghost-node method of LGR2 provides a more rigorous coupling in which the solution accuracy is controlled by convergence criteria defined by the user. In realistic problems, this can result in substantially more accurate solutions and require an increase in computer processing time. The rigorous coupling enables sensitivity analysis, parameter estimation, and uncertainty analysis that reflects conditions in both model grids. This report describes the method used by LGR2, evaluates accuracy and performance for two-and three-dimensional test cases, provides input instructions, and lists selected input and output files for an example problem. It also presents the Boundary Flow and Head (BFH2) Package, which allows the child and parent models to be simulated independently using the boundary conditions obtained through the iterative process of LGR2.

MODFLOW-2005, the U.S. Geological Survey modular ground-water model - documentation of shared node local grid refinement (LGR) and the boundary flow and head (BFH) package

USGS Publications Warehouse

Mehl, Steffen W.; Hill, Mary C.

2006-01-01

This report documents the addition of shared node Local Grid Refinement (LGR) to MODFLOW-2005, the U.S. Geological Survey modular, transient, three-dimensional, finite-difference ground-water flow model. LGR provides the capability to simulate ground-water flow using one block-shaped higher-resolution local grid (a child model) within a coarser-grid parent model. LGR accomplishes this by iteratively coupling two separate MODFLOW-2005 models such that heads and fluxes are balanced across the shared interfacing boundary. LGR can be used in two-and three-dimensional, steady-state and transient simulations and for simulations of confined and unconfined ground-water systems. Traditional one-way coupled telescopic mesh refinement (TMR) methods can have large, often undetected, inconsistencies in heads and fluxes across the interface between two model grids. The iteratively coupled shared-node method of LGR provides a more rigorous coupling in which the solution accuracy is controlled by convergence criteria defined by the user. In realistic problems, this can result in substantially more accurate solutions and require an increase in computer processing time. The rigorous coupling enables sensitivity analysis, parameter estimation, and uncertainty analysis that reflects conditions in both model grids. This report describes the method used by LGR, evaluates LGR accuracy and performance for two- and three-dimensional test cases, provides input instructions, and lists selected input and output files for an example problem. It also presents the Boundary Flow and Head (BFH) Package, which allows the child and parent models to be simulated independently using the boundary conditions obtained through the iterative process of LGR.

LASIK flap characteristics using the Moria M2 microkeratome with the 90-microm single use head.

PubMed

Aslanides, Ioannis M; Tsiklis, Nikolaos S; Astyrakakis, Nikolaos I; Pallikaris, Ioannis G; Jankov, Mirko R

2007-01-01

To evaluate the accuracy and consistency of corneal flap thickness, horizontal diameter, and hinge size with the Moria M2 90-microm single use head. Fifty-two myopic patients (104 eyes), mean age 32.6 years, underwent bilateral LASIK with a superior hinged flap using the Moria M2 microkeratome (90-microm single use head). Prospective evaluation included flap thickness (subtraction method), diameter, hinge size, interface particles, intraoperative complications, and visual recovery. The mean preoperative spherical equivalent refraction was -5.72 +/- 2.59 diopters (D) (range: -2.88 to -10.75 D) and -5.84 +/- 2.73 D (range: -3.13 to -9.38 D) for right and left eyes, respectively. The mean preoperative central corneal thickness was 548 +/- 24 microm and 547 +/- 25 microm for right and left eyes, respectively. The mean preoperative steepest K was 44.12 +/- 1.28 D and 44.41 +/- 1.27 D for right and left eyes, respectively. Corneal diameter (white-to-white) was 12 +/- 0.4 mm and 11.9 +/- 0.4 mm for right and left eyes, respectively. The mean postoperative flap thickness was 109 +/- 18 microm (range: 67 to 152 microm) and 103 +/- 15 microm (range: 65 to 151 microm) for right and left eyes, respectively. The mean postoperative flap diameter was 9.4 +/- 0.3 mm (expected mean according to the nomogram given by the company was 9.5 mm). The mean postoperative hinge chord was 4.4 +/- 0.4 mm (expected mean 4.2 mm). No interface particles were detected on slit-lamp examination. The Moria M2 90-microm single use head is safe with reasonable predictability for LASIK flap creation.

Pilot vehicle interface on the advanced fighter technology integration F-16

NASA Technical Reports Server (NTRS)

Dana, W. H.; Smith, W. B.; Howard, J. D.

1986-01-01

This paper focuses on the work load aspects of the pilot vehicle interface in regard to the new technologies tested during AMAS Phase II. Subjects discussed in this paper include: a wide field-of-view head-up display; automated maneuvering attack system/sensor tracker system; master modes that configure flight controls and mission avionics; a modified helmet mounted sight; improved multifunction display capability; a voice interactive command system; ride qualities during automated weapon delivery; a color moving map; an advanced digital map display; and a g-induced loss-of-consciousness and spatial disorientation autorecovery system.

High-resolution, continuous field-of-view (FOV), non-rotating imaging system

NASA Technical Reports Server (NTRS)

Huntsberger, Terrance L. (Inventor); Stirbl, Robert C. (Inventor); Aghazarian, Hrand (Inventor); Padgett, Curtis W. (Inventor)

2010-01-01

A high resolution CMOS imaging system especially suitable for use in a periscope head. The imaging system includes a sensor head for scene acquisition, and a control apparatus inclusive of distributed processors and software for device-control, data handling, and display. The sensor head encloses a combination of wide field-of-view CMOS imagers and narrow field-of-view CMOS imagers. Each bank of imagers is controlled by a dedicated processing module in order to handle information flow and image analysis of the outputs of the camera system. The imaging system also includes automated or manually controlled display system and software for providing an interactive graphical user interface (GUI) that displays a full 360-degree field of view and allows the user or automated ATR system to select regions for higher resolution inspection.

Experiments in teleoperator and autonomous control of space robotic vehicles

NASA Technical Reports Server (NTRS)

Alexander, Harold L.

1991-01-01

A program of research embracing teleoperator and automatic navigational control of freely flying satellite robots is presented. Current research goals include: (1) developing visual operator interfaces for improved vehicle teleoperation; (2) determining the effects of different visual interface system designs on operator performance; and (3) achieving autonomous vision-based vehicle navigation and control. This research program combines virtual-environment teleoperation studies and neutral-buoyancy experiments using a space-robot simulator vehicle currently under development. Visual-interface design options under investigation include monoscopic versus stereoscopic displays and cameras, helmet-mounted versus panel-mounted display monitors, head-tracking versus fixed or manually steerable remote cameras, and the provision of vehicle-fixed visual cues, or markers, in the remote scene for improved sensing of vehicle position, orientation, and motion.

Defining brain-machine interface applications by matching interface performance with device requirements.

PubMed

Tonet, Oliver; Marinelli, Martina; Citi, Luca; Rossini, Paolo Maria; Rossini, Luca; Megali, Giuseppe; Dario, Paolo

2008-01-15

Interaction with machines is mediated by human-machine interfaces (HMIs). Brain-machine interfaces (BMIs) are a particular class of HMIs and have so far been studied as a communication means for people who have little or no voluntary control of muscle activity. In this context, low-performing interfaces can be considered as prosthetic applications. On the other hand, for able-bodied users, a BMI would only be practical if conceived as an augmenting interface. In this paper, a method is introduced for pointing out effective combinations of interfaces and devices for creating real-world applications. First, devices for domotics, rehabilitation and assistive robotics, and their requirements, in terms of throughput and latency, are described. Second, HMIs are classified and their performance described, still in terms of throughput and latency. Then device requirements are matched with performance of available interfaces. Simple rehabilitation and domotics devices can be easily controlled by means of BMI technology. Prosthetic hands and wheelchairs are suitable applications but do not attain optimal interactivity. Regarding humanoid robotics, the head and the trunk can be controlled by means of BMIs, while other parts require too much throughput. Robotic arms, which have been controlled by means of cortical invasive interfaces in animal studies, could be the next frontier for non-invasive BMIs. Combining smart controllers with BMIs could improve interactivity and boost BMI applications.

Analysis of groundwater flow and stream depletion in L-shaped fluvial aquifers

NASA Astrophysics Data System (ADS)

Lin, Chao-Chih; Chang, Ya-Chi; Yeh, Hund-Der

2018-04-01

Understanding the head distribution in aquifers is crucial for the evaluation of groundwater resources. This article develops a model for describing flow induced by pumping in an L-shaped fluvial aquifer bounded by impermeable bedrocks and two nearly fully penetrating streams. A similar scenario for numerical studies was reported in Kihm et al. (2007). The water level of the streams is assumed to be linearly varying with distance. The aquifer is divided into two subregions and the continuity conditions of the hydraulic head and flux are imposed at the interface of the subregions. The steady-state solution describing the head distribution for the model without pumping is first developed by the method of separation of variables. The transient solution for the head distribution induced by pumping is then derived based on the steady-state solution as initial condition and the methods of finite Fourier transform and Laplace transform. Moreover, the solution for stream depletion rate (SDR) from each of the two streams is also developed based on the head solution and Darcy's law. Both head and SDR solutions in the real time domain are obtained by a numerical inversion scheme called the Stehfest algorithm. The software MODFLOW is chosen to compare with the proposed head solution for the L-shaped aquifer. The steady-state and transient head distributions within the L-shaped aquifer predicted by the present solution are compared with the numerical simulations and measurement data presented in Kihm et al. (2007).

Head movement compensation in real-time magnetoencephalographic recordings.

PubMed

Little, Graham; Boe, Shaun; Bardouille, Timothy

2014-01-01

Neurofeedback- and brain-computer interface (BCI)-based interventions can be implemented using real-time analysis of magnetoencephalographic (MEG) recordings. Head movement during MEG recordings, however, can lead to inaccurate estimates of brain activity, reducing the efficacy of the intervention. Most real-time applications in MEG have utilized analyses that do not correct for head movement. Effective means of correcting for head movement are needed to optimize the use of MEG in such applications. Here we provide preliminary validation of a novel analysis technique, real-time source estimation (rtSE), that measures head movement and generates corrected current source time course estimates in real-time. rtSE was applied while recording a calibrated phantom to determine phantom position localization accuracy and source amplitude estimation accuracy under stationary and moving conditions. Results were compared to off-line analysis methods to assess validity of the rtSE technique. The rtSE method allowed for accurate estimation of current source activity at the source-level in real-time, and accounted for movement of the source due to changes in phantom position. The rtSE technique requires modifications and specialized analysis of the following MEG work flow steps.•Data acquisition•Head position estimation•Source localization•Real-time source estimation This work explains the technical details and validates each of these steps.

Press-fit bipolar radial head arthroplasty, midterm results.

PubMed

Kodde, Izaäk F; Heijink, Andras; Kaas, Laurens; Mulder, Paul G H; van Dijk, C Niek; Eygendaal, Denise

2016-08-01

Theoretical advantages of bipolar compared with monopolar radial head arthroplasty include better accommodation of radiocapitellar malalignment, reduction of capitellar abrasion, and reduction of stress at the bone-implant interfaces. Our purpose was to report the midterm results of press-fit bipolar radial head arthroplasty. Thirty patients were treated by press-fit bipolar radial head arthroplasty for acute fracture of the radial head, failed earlier treatment, or post-traumatic sequelae. Three patients were lost to follow-up. Results are presented for the remaining 27 patients. At mean follow-up of 48 months (range, 28-73), there had been 3 (11%) revisions. Two involved conversion to prosthetic radiocapitellar hemiarthroplasty for symptomatic capitellar abrasion; a third involved exchange of the articular component (ie, head) for instability. In all, the stems appeared well fixed. A prosthesis in a subluxed position accounted for the 1 (4%) additional radiologic failure. The average flexion-extension arc was 136° (range, 120°-145°), and the average pronation-supination arc was 138° (range, 70°-180°). According to the Mayo Elbow Performance Score, the combined excellent and good results accounted for 70%. The overall midterm outcome of this series of 30 press-fit bipolar radial head arthroplasties can be considered favorable. Although the revision rate was 11%, the stems were well fixed in all. There was 1 (4%) additional radiologic failure. We suggest considering a press-fit bipolar radial head prosthesis for acute comminuted radial head fractures with limited bone loss of the proximal radius. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Social Sciences in Forestry, A Current Selected Bibliography, No. 55, June 1981.

ERIC Educational Resources Information Center

Schwab, Judith L., Ed.

Documents which address the interface between forestry and the social sciences comprise this annotated bibliography. The publications described are grouped under five headings: (1) social science applied to forestry at large; (2) applied to forestry's productive agents; (3) applied to forest production; (4) applied to manufacturing; and (5)…

Elin@: Electronic Library Information Navigator--Towards the "One Stop Shop" Information

ERIC Educational Resources Information Center

Alwerud, Anna; Jorgensen, Lotte

2005-01-01

Libraries subscribe to thousands of electronic journals and they are difficult for end-users to find. Journal and publisher interfaces and functionalities differ considerably. The recent development in e-media calls for central management of the resources. Lund University Libraries' Head Office has developed a service for presentation and…

Enhancing Image Findability through a Dual-Perspective Navigation Framework

ERIC Educational Resources Information Center

Lin, Yi-Ling

2013-01-01

This dissertation focuses on investigating whether users will locate desired images more efficiently and effectively when they are provided with information descriptors from both experts and the general public. This study develops a way to support image finding through a human-computer interface by providing subject headings and social tags about…

Workshop on the interface between radiation chemistry and radiation physics

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

Not Available

1983-03-01

Twenty-four papers are grouped under the session headings: measurements of physical and chemical properties, track structure modeling, spurs and track structure, and the 10/sup -16/ to 10/sup -12/ second region. Separate abstracts were prepared for 12 of the papers; four of the remaining papers had previously been abstracted. (DLC)

Optimizations and Applications in Head-Mounted Video-Based Eye Tracking

ERIC Educational Resources Information Center

Li, Feng

2011-01-01

Video-based eye tracking techniques have become increasingly attractive in many research fields, such as visual perception and human-computer interface design. The technique primarily relies on the positional difference between the center of the eye's pupil and the first-surface reflection at the cornea, the corneal reflection (CR). This…

Dialogue with an OPAC: How Visionary Was Swanson in 1964?

ERIC Educational Resources Information Center

Su, Shiao-Feng

1994-01-01

Traces the development of online public access catalogs (OPACs) and compares what has occurred with a 1964 article that outlined recommendations for a future card catalog. Subject access is emphasized, including Library of Congress Subject Headings, expansion of OPACs, user-friendly interfaces, new technologies, and current visions of the future…

Summary of ground-water conditions in the Jaffna Peninsula, Republic of Sri Lanka, with a plan for investigating feasibility of ground-water development

USGS Publications Warehouse

Meisler, Harold

1977-01-01

Ground water in the Jaffna Peninsula of Sri Lanka, Ceylon, occurs within solution openings of the Jaffna Limestone of Miocene age. The freshwater forms a complex of lenses up to 25 meters thick overlying saline water derived from the sea. Salt-water intrusion and upconing of the salt water has occurred at several locations primarily along the coast. Recharge to the aquifer occurs during October-December. Discharge is primarily to wells and to springs along the north coast. Spring discharge is small compared to withdrawal from wells. Pumping from wells in an intensively studied 142-square-kilometer area of the Peninsula was 55.5 million cubic meters in 1976, whereas discharge to visible springs was an estimated 9.3 million cubic meters. Pumping during January-September removes water from storage causing heads to decline and the salt water-freshwater interface to rise. The storage is replenished as heads increase and the interface is depressed during the following October-December. Consequently, most of the recharge goes into storage rather than discharging to the sea. (Woodard-USGS)

Cavitating flow during water hammer using a generalized interface vaporous cavitation model

NASA Astrophysics Data System (ADS)

Sadafi, Mohamadhosein; Riasi, Alireza; Nourbakhsh, Seyed Ahmad

2012-10-01

In a transient flow simulation, column separation may occur when the calculated pressure head decreases to the saturated vapor pressure head in a computational grid. Abrupt valve closure or pump failure can result in a fast transient flow with column separation, potentially causing problems such as pipe failure, hydraulic equipment damage, cavitation or corrosion. This paper reports a numerical study of water hammer with column separation in a simple reservoir-pipeline-valve system and pumping station. The governing equations for two-phase transient flow in pipes are solved based on the method of characteristics (MOC) using a generalized interface vaporous cavitating model (GIVCM). The numerical results were compared with the experimental data for validation purposes, and the comparison indicated that the GIVCM describes the experimental results more accurately than the discrete vapor cavity model (DVCM). In particular, the GIVCM correlated better with the experimental data than the DVCM in terms of timing and pressure magnitude. The effects of geometric and hydraulic parameters on flow behavior in a pumping station with column separation were also investigated in this study.

Mass transport at rotating disk electrodes: effects of synthetic particles and nerve endings.

PubMed

Chiu, Veronica M; Lukus, Peter A; Doyle, Jamie L; Schenk, James O

2011-11-01

An unstirred layer (USL) exists at the interface of solids with solutions. Thus, the particles in brain tissue preparations possess a USL as well as at the surface of a rotating disk electrode (RDE) used to measure chemical fluxes. Time constraints for observing biological kinetics based on estimated thicknesses of USLs at the membrane surface in real samples of nerve endings were estimated. Liposomes, silica, and Sephadex were used separately to model the tissue preparation particles. Within a solution stirred by the RDE, both diffusion and hydrodynamic boundary layers are formed. It was observed that the number and size of particles decreased the following: the apparent diffusion coefficient excluding Sephadex, boundary layer thicknesses excluding silica, sensitivity excluding diluted liposomes (in agreement with results from other laboratories), limiting current potentially due to an increase in the path distance, and mixing time. They have no effect on the detection limit (6 ± 2 nM). The RDE kinetically resolves transmembrane transport with a timing of approximately 30 ms. Copyright © 2011 Elsevier Inc. All rights reserved.

X-window-based 2K display workstation

NASA Astrophysics Data System (ADS)

Weinberg, Wolfram S.; Hayrapetian, Alek S.; Cho, Paul S.; Valentino, Daniel J.; Taira, Ricky K.; Huang, H. K.

1991-07-01

A high-definition, high-performance display station for reading and review of digital radiological images is introduced. The station is based on a Sun SPARC Station 4 and employs X window system for display and manipulation of images. A mouse-operated graphic user interface is implemented utilizing Motif-style tools. The system supports up to four MegaScan gray-scale 2560 X 2048 monitors. A special configuration of frame and video buffer yields a data transfer of 50 M pixels/s. A magnetic disk array supplies a storage capacity of 2 GB with a data transfer rate of 4-6 MB/s. The system has access to the central archive through an ultrahigh-speed fiber-optic network and patient studies are automatically transferred to the local disk. The available image processing functions include change of lookup table, zoom and pan, and cine. Future enhancements will provide for manual contour tracing, length, area, and density measurements, text and graphic overlay, as well as composition of selected images. Additional preprocessing procedures under development will optimize the initial lookup table and adjust the images to a standard orientation.

Air entrapment under an impacting drop

NASA Astrophysics Data System (ADS)

Thoroddsen, S. T.; Etoh, T. G.; Takehara, K.

2003-03-01

When a drop impacts on a liquid surface it entraps a small amount of air under its centre as the two liquid surfaces meet. The contact occurs along a ring enclosing a thin disk of air. We use the next-generation ultra-high-speed video camera, capable of 1 million f.p.s. (Etoh et al. 2002), to study the dynamics of this air sheet as it contracts due to surface tension, to form a bubble or, more frequently, splits into two bubbles. During the contraction of the air disk an azimuthal undulation, resembling a pearl necklace, develops along its edge. The contraction speed of the sheet is accurately described by a balance between inertia and surface tension. The average initial thickness of the air sheet decreases with higher impact Reynolds numbers, becoming less than one micron. The total volume of air entrapped depends strongly on the bottom curvature of the drop at impact. A sheet of micro-bubbles is often observed along the original interface. Oguz Prosperetti bubble rings are also observed. For low Weber numbers (We<20) a variety of other entrapment phenomena appear.

Radiative thermal conduction fronts

NASA Technical Reports Server (NTRS)

Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

1990-01-01

The discovery of the O VI interstellar absorption lines in our Galaxy by the Copernicus observatory was a turning point in our understanding of the Interstellar Medium (ISM). It implied the presence of widespread hot (approx. 10 to the 6th power K) gas in disk galaxies. The detection of highly ionized species in quasi-stellar objects' absorption spectra may be the first indirect observation of this hot phase in external disk galaxies. Previous efforts to understand extensive O VI absorption line data from our Galaxy were not very successful in locating the regions where this absorption originates. The location at interfaces between evaporating ISM clouds and hot gas was favored, but recent studies of steady-state conduction fronts in spherical clouds by Ballet, Arnaud, and Rothenflug (1986) and Bohringer and Hartquist (1987) rejected evaporative fronts as the absorption sites. Researchers report here on time-dependent nonequilibrium calculations of planar conductive fronts whose properties match well with observations, and suggest reasons for the difference between the researchers' results and the above. They included magnetic fields in additional models, not reported here, and the conclusions are not affected by their presence.

Radiative thermal conduction fronts

NASA Astrophysics Data System (ADS)

Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

1990-07-01

The discovery of the O VI interstellar absorption lines in our Galaxy by the Copernicus observatory was a turning point in our understanding of the Interstellar Medium (ISM). It implied the presence of widespread hot (approx. 10 to the 6th power K) gas in disk galaxies. The detection of highly ionized species in quasi-stellar objects' absorption spectra may be the first indirect observation of this hot phase in external disk galaxies. Previous efforts to understand extensive O VI absorption line data from our Galaxy were not very successful in locating the regions where this absorption originates. The location at interfaces between evaporating ISM clouds and hot gas was favored, but recent studies of steady-state conduction fronts in spherical clouds by Ballet, Arnaud, and Rothenflug (1986) and Bohringer and Hartquist (1987) rejected evaporative fronts as the absorption sites. Researchers report here on time-dependent nonequilibrium calculations of planar conductive fronts whose properties match well with observations, and suggest reasons for the difference between the researchers' results and the above. They included magnetic fields in additional models, not reported here, and the conclusions are not affected by their presence.

Fluorescence Imaging of Underexpanded Jets and Comparison with CFD

NASA Technical Reports Server (NTRS)

Wilkes, Jennifer A.; Glass, Christopher E.; Danehy, Paul M.; Nowak, Robert J.

2006-01-01

An experimental study of underexpanded and highly underexpanded axisymmetric nitrogen free jets seeded with 0.5% nitric oxide (NO) and issuing from a sonic orifice was conducted at NASA Langley Research Center. Reynolds numbers based on nozzle exit conditions ranged from 770 to 35,700, and nozzle exit-to-ambient jet pressure ratios ranged from 2 to 35. These flows were non-intrusively visualized with a spatial resolution of approximately 0.14 mm x 0.14 mm x 1 mm thick and a temporal resolution of 1 s using planar laser-induced fluorescence (PLIF) of NO, with the laser tuned to the strongly-fluorescing UV absorption bands of the Q1 band head near 226.256 nm. Three laminar cases were selected for comparison with computational fluid dynamics (CFD). The cases were run using GASP (General Aerodynamic Simulation Program) Version 4. Comparisons of the fundamental wavelength of the jet flow showed good agreement between CFD and experiment for all three test cases, while comparisons of Mach disk location and Mach disk diameter showed good agreement at lower jet pressure ratios, with a tendency to slightly underpredict these parameters with increasing jet pressure ratio.

Nemesis I: Parallel Enhancements to ExodusII

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

Hennigan, Gary L.; John, Matthew S.; Shadid, John N.

2006-03-28

NEMESIS I is an enhancement to the EXODUS II finite element database model used to store and retrieve data for unstructured parallel finite element analyses. NEMESIS I adds data structures which facilitate the partitioning of a scalar (standard serial) EXODUS II file onto parallel disk systems found on many parallel computers. Since the NEMESIS I application programming interface (APl)can be used to append information to an existing EXODUS II files can be used on files which contain NEMESIS I information. The NEMESIS I information is written and read via C or C++ callable functions which compromise the NEMESIS I API.

Interface Properties and Surface Leakage of HgCdTe Photodiodes.

DTIC Science & Technology

1980-01-01

these techniques, we found that (a) the com- position of a 1200 )anodic film is 68% TeO2 , 27% CdO, and 6% HgO, and (b) the cations, especially the Hg...of TeO2 (Fig. 1); (b) irradiation with an electron beam of a few keV energy can convert the surface layer (10-100 1) of (Rg,Cd)Te into CdTe (Fig. 2...remove the scratches. The polishing cloth was secured to a glass olishing disk which is not affected by the corrosive nature of the etch - a 5

Flight Deck Display Technologies for 4DT and Surface Equivalent Visual Operations

NASA Technical Reports Server (NTRS)

Prinzel, Lawrence J., III; Jones, Denis R.; Shelton, Kevin J.; Arthur, Jarvis J., III; Bailey, Randall E.; Allamandola, Angela S.; Foyle, David C.; Hooey, Becky L.

2009-01-01

NASA research is focused on flight deck display technologies that may significantly enhance situation awareness, enable new operating concepts, and reduce the potential for incidents/accidents for terminal area and surface operations. The display technologies include surface map, head-up, and head-worn displays; 4DT guidance algorithms; synthetic and enhanced vision technologies; and terminal maneuvering area traffic conflict detection and alerting systems. This work is critical to ensure that the flight deck interface technologies and the role of the human participants can support the full realization of the Next Generation Air Transportation System (NextGen) and its novel operating concepts.

Large Metal Heads and Vitamin E Polyethylene Increase Frictional Torque in Total Hip Arthroplasty.

PubMed

Meneghini, R Michael; Lovro, Luke R; Wallace, Joseph M; Ziemba-Davis, Mary

2016-03-01

Trunnionosis has reemerged in modern total hip arthroplasty for reasons that remain unclear. Bearing frictional torque transmits forces to the modular head-neck interface, which may contribute to taper corrosion. The purpose of this study is to compare frictional torque of modern bearing couples in total hip arthroplasty. Mechanical testing based on in vivo loading conditions was used to measure frictional torque. All bearing couples were lubricated and tested at 1 Hz for more than 2000 cycles. The bearing couples tested included conventional, highly crosslinked (XLPE) and vitamin E polyethylene, CoCr, and ceramic femoral heads and dual-mobility bearings. Statistical analysis was performed using Student t test for single-variable and analysis of variance for multivariant analysis. P ≤ .05 was considered statistically significant. Large CoCr metal heads (≥36 mm) substantially increased frictional torque against XLPE liners (P = .01), a finding not observed in ceramic heads. Vitamin E polyethylene substantially increased frictional torque compared with XLPE in CoCr and ceramic heads (P = .001), whereas a difference between conventional and XLPE was not observed (P = .69) with the numbers available. Dual-mobility bearing with ceramic inner head demonstrated the lowest mean frictional torque of all bearing couples. In this simulated in vivo model, large-diameter CoCr femoral heads and vitamin E polyethylene liners are associated with increased frictional torque compared with smaller metal heads and XLPE, respectively. The increased frictional torque of vitamin E polyethylene and larger-diameter femoral heads should be considered and further studied, along with reported benefits of these modern bearing couples. Copyright © 2016 Elsevier Inc. All rights reserved.

Immobilization of paracetamol and benzocaine pro-drug derivatives as long-range self-organized monolayers on graphite.

PubMed

Popoff, Alexandre; Fichou, Denis

2008-05-01

We show here by means of scanning tunneling microscopy (STM) at the liquid/solid interface that paracetamol and benzocaine molecules bearing a long aliphatic chain can be immobilized on highly oriented pyrolitic graphite (HOPG) as perfectly ordered two-dimensional domains extending over several hundreds of nanometers. In both cases, high-resolution STM images reveal that compounds 1 and 2 self-assemble into parallel lamellae having a head-to-head arrangement. The paracetamol heads of 1 are in a zigzag position with entangled n-dodecyloxy side chains while benzocaine heads of compound 2 are perfectly aligned as a double row and have their palmitic side chains on either sides of the head alignment. We attribute the very long-range ordering of these two pro-drug derivatives on HOPG to the combined effects of intermolecular H-bonding on one side and Van der Waals interactions between aliphatic side chains and graphite on the other side. The 2D immobilization of pro-drug derivatives via a non-destructive physisorption mechanism could prove to be useful for applications such as drug delivery if it can be realized on a biocompatible substrate.

Ultra-fast movies of thin-film laser ablation

NASA Astrophysics Data System (ADS)

Domke, Matthias; Rapp, Stephan; Schmidt, Michael; Huber, Heinz P.

2012-11-01

Ultra-short-pulse laser irradiation of thin molybdenum films from the glass substrate side initiates an intact Mo disk lift off free from thermal effects. For the investigation of the underlying physical effects, ultra-fast pump-probe microscopy is used to produce stop-motion movies of the single-pulse ablation process, initiated by a 660-fs laser pulse. The ultra-fast dynamics in the femtosecond and picosecond ranges are captured by stroboscopic illumination of the sample with an optically delayed probe pulse of 510-fs duration. The nanosecond and microsecond delay ranges of the probe pulse are covered by an electronically triggered 600-ps laser. Thus, the setup enables an observation of general laser ablation processes from the femtosecond delay range up to the final state. A comparison of time- and space-resolved observations of film and glass substrate side irradiation of a 470-nm molybdenum layer reveals the driving mechanisms of the Mo disk lift off initiated by glass-side irradiation. Observations suggest that a phase explosion generates a liquid-gas mixture in the molybdenum/glass interface about 10 ps after the impact of the pump laser pulse. Then, a shock wave and gas expansion cause the molybdenum layer to bulge, while the enclosed liquid-gas mixture cools and condenses at delay times in the 100-ps range. The bulging continues for approximately 20 ns, when an intact Mo disk shears and lifts off at a velocity of above 70 m/s. As a result, the remaining hole is free from thermal effects.

Self-Adhesive and Capacitive Carbon Nanotube-Based Electrode to Record Electroencephalograph Signals From the Hairy Scalp.

PubMed

Lee, Seung Min; Kim, Jeong Hun; Park, Cheolsoo; Hwang, Ji-Young; Hong, Joung Sook; Lee, Kwang Ho; Lee, Sang Hoon

2016-01-01

We fabricated a carbon nanotube (CNT)/adhesive polydimethylsiloxane (aPDMS) composite-based dry electroencephalograph (EEG) electrode for capacitive measuring of EEG signals. As research related to brain-computer interface applications has advanced, the presence of hairs on a patient's scalp has continued to present an obstacle to recorder EEG signals using dry electrodes. The CNT/aPDMS electrode developed here is elastic, highly conductive, self-adhesive, and capable of making conformal contact with and attaching to a hairy scalp. Onto the conductive disk, hundreds of conductive pillars coated with Parylene C insulation layer were fabricated. A CNT/aPDMS layer was attached on the disk to transmit biosignals to the pillar. The top of disk was designed to be solderable, which enables the electrode to connect with a variety of commercial EEG acquisition systems. The mechanical and electrical characteristics of the electrode were tested, and the performances of the electrodes were evaluated by recording EEGs, including alpha rhythms, auditory-evoked potentials, and steady-state visually-evoked potentials. The results revealed that the electrode provided a high signal-to-noise ratio with good tolerance for motion. Almost no leakage current was observed. Although preamplifiers with ultrahigh input impedance have been essential for previous capacitive electrodes, the EEGs were recorded here by directly connecting a commercially available EEG acquisition system to the electrode to yield high-quality signals comparable to those obtained using conventional wet electrodes.

DCOMP Award Lecture (Metropolis): A 3D Spectral Anelastic Hydrodynamic Code for Shearing, Stratified Flows

NASA Astrophysics Data System (ADS)

Barranco, Joseph

2006-03-01

We have developed a three-dimensional (3D) spectral hydrodynamic code to study vortex dynamics in rotating, shearing, stratified systems (eg, the atmosphere of gas giant planets, protoplanetary disks around newly forming protostars). The time-independent background state is stably stratified in the vertical direction and has a unidirectional linear shear flow aligned with one horizontal axis. Superposed on this background state is an unsteady, subsonic flow that is evolved with the Euler equations subject to the anelastic approximation to filter acoustic phenomena. A Fourier-Fourier basis in a set of quasi-Lagrangian coordinates that advect with the background shear is used for spectral expansions in the two horizontal directions. For the vertical direction, two different sets of basis functions have been implemented: (1) Chebyshev polynomials on a truncated, finite domain, and (2) rational Chebyshev functions on an infinite domain. Use of this latter set is equivalent to transforming the infinite domain to a finite one with a cotangent mapping, and using cosine and sine expansions in the mapped coordinate. The nonlinear advection terms are time integrated explicitly, whereas the Coriolis force, buoyancy terms, and pressure/enthalpy gradient are integrated semi- implicitly. We show that internal gravity waves can be damped by adding new terms to the Euler equations. The code exhibits excellent parallel performance with the Message Passing Interface (MPI). As a demonstration of the code, we simulate vortex dynamics in protoplanetary disks and the Kelvin-Helmholtz instability in the dusty midplanes of protoplanetary disks.

Reexamination of Induction Heating of Primitive Bodies in Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Menzel, Raymond L.; Roberge, Wayne G.

2013-10-01

We reexamine the unipolar induction mechanism for heating asteroids originally proposed in a classic series of papers by Sonett and collaborators. As originally conceived, induction heating is caused by the "motional electric field" that appears in the frame of an asteroid immersed in a fully ionized, magnetized solar wind and drives currents through its interior. However, we point out that classical induction heating contains a subtle conceptual error, in consequence of which the electric field inside the asteroid was calculated incorrectly. The problem is that the motional electric field used by Sonett et al. is the electric field in the freely streaming plasma far from the asteroid; in fact, the motional field vanishes at the asteroid surface for realistic assumptions about the plasma density. In this paper we revisit and improve the induction heating scenario by (1) correcting the conceptual error by self-consistently calculating the electric field in and around the boundary layer at the asteroid-plasma interface; (2) considering weakly ionized plasmas consistent with current ideas about protoplanetary disks; and (3) considering more realistic scenarios that do not require a fully ionized, powerful T Tauri wind in the disk midplane. We present exemplary solutions for two highly idealized flows that show that the interior electric field can either vanish or be comparable to the fields predicted by classical induction depending on the flow geometry. We term the heating driven by these flows "electrodynamic heating," calculate its upper limits, and compare them to heating produced by short-lived radionuclides.

Influence of Laser Power on the Microstructure and Mechanical Properties of a Laser Welded-Brazed Mg Alloy/Ni-Coated Steel Dissimilar Joint

NASA Astrophysics Data System (ADS)

Tan, Caiwang; Xiao, Liyuan; Liu, Fuyun; Chen, Bo; Song, Xiaoguo; Li, Liqun; Feng, Jicai

2017-05-01

In this work, we describe a method to improve the bonding of an immiscible Mg/steel system using Ni as an interlayer by coating it on the steel surface. Laser welding-brazing of AZ31B Mg alloy to Ni-coated Q235 steel using Mg-based filler was performed in a lap configuration. The influence of laser power on the weld characteristics, including joint appearance, formation of interfacial reaction layers and mechanical properties was investigated. The results indicated that the presence of the Ni-coating promoted the wetting of the liquid filler metal on the steel surface. A thermal gradient along the interface led to the formation of heterogeneous interfacial reaction layers. When using a low laser power of 1600 W, the reaction products were an FeAl phase in the direct laser irradiation zone, an AlNi phase close to the intermediate zone and mixtures of AlNi phase and an (α-Mg + Mg2Ni) eutectic structure near the interface at the seam head zone. For high powers of more than 2000 W, the FeAl phase grew thicker in the direct laser irradiation zone and a new Fe(Ni) transition layer formed at the interface of the intermediate zone and the seam head zone. However, the AlNi phase and (α-Mg + Mg2Ni) eutectic structure were scattered at the Mg seam. All the joints fractured at the fusion zone, indicating that the improved interface was not the weakest joint region. The maximum tensile-shear strength of the Mg/Ni-coated steel joint reached 190 N/mm, and the joint efficiency was 70% with respect to the Mg alloy base metal.

The measurement of tissue interface pressures and changes in jugular venous parameters associated with cervical immobilisation devices: a systematic review

PubMed Central

2013-01-01

Cervical immobilisation is commonly applied following trauma, particularly blunt head injury, but current methods of immobilisation are associated with significant complications. Semi-rigid disposable cervical collars are known to cause pressure ulcers, and impede effective airway management. These collars may also exacerbate a head injury by increasing intracranial pressure as a result of external compression of the jugular veins. There is a clear imperative to find ways of effectively immobilising the cervical spine whilst minimising complications, and any assessment of existing or new devices should include a standardized approach to the measurement of tissue interface pressures and their effect on jugular venous drainage from the brain. This systematic review summarises the research methods and technologies that have been used to measure tissue interface pressure and assess the jugular vein in the context of cervical immobilisation devices. 27 papers were included and assessed for quality. Laboratory investigations and biomechanical studies have gradually given way to methods that more accurately reflect clinical care. There are numerous accounts of skin ulceration associated with cervical collars, but no standardised approach to measuring tissue interface pressure. It is therefore difficult to compare studies and devices, but a pressure of less than 30 mmHg appears desirable. Cervical collars have been shown to have a compressive effect on the jugular veins, but it is not yet certain that this is the cause of the increased intracranial pressure observed in association with cervical collar use. This is the first review of its type. It will help guide further research in this area of trauma care, and the development and testing of new cervical immobilisation devices. PMID:24299024

Upgrade to MODFLOW-GUI; addition of MODPATH, ZONEBDGT, and additional MODFLOW packages to the U.S. Geological Survey MODFLOW-96 Graphical-User Interface

USGS Publications Warehouse

Winston, R.B.

1999-01-01

This report describes enhancements to a Graphical-User Interface (GUI) for MODFLOW-96, the U.S. Geological Survey (USGS) modular, three-dimensional, finitedifference ground-water flow model, and MOC3D, the USGS three-dimensional, method-ofcharacteristics solute-transport model. The GUI is a plug-in extension (PIE) for the commercial program Argus ONEe. The GUI has been modified to support MODPATH (a particle tracking post-processing package for MODFLOW), ZONEBDGT (a computer program for calculating subregional water budgets), and the Stream, Horizontal-Flow Barrier, and Flow and Head Boundary packages in MODFLOW. Context-sensitive help has been added to make the GUI easier to use and to understand. In large part, the help consists of quotations from the relevant sections of this report and its predecessors. The revised interface includes automatic creation of geospatial information layers required for the added programs and packages, and menus and dialog boxes for input of parameters for simulation control. The GUI creates formatted ASCII files that can be read by MODFLOW-96, MOC3D, MODPATH, and ZONEBDGT. All four programs can be executed within the Argus ONEe application (Argus Interware, Inc., 1997). Spatial results of MODFLOW-96, MOC3D, and MODPATH can be visualized within Argus ONEe. Results from ZONEBDGT can be visualized in an independent program that can also be used to view budget data from MODFLOW, MOC3D, and SUTRA. Another independent program extracts hydrographs of head or drawdown at individual cells from formatted MODFLOW head and drawdown files. A web-based tutorial on the use of MODFLOW with Argus ONE has also been updated. The internal structure of the GUI has been modified to make it possible for advanced users to easily customize the GUI. Two additional, independent PIE?s were developed to allow users to edit the positions of nodes and to facilitate exporting the grid geometry to external programs.

Freshwater-Brine Mixing Zone Hydrodynamics in Salt Flats (Salar de Atacama)

NASA Astrophysics Data System (ADS)

Marazuela, M. A.; Vázquez-Suñé, E.; Custodio, E.; Palma, T.; García-Gil, A.

2017-12-01

The increase in the demand of strategic minerals for the development of medicines and batteries require detailed knowledge of the salt flats freshwater-brine interface to make its exploitation efficient. The interface zone is the result of a physical balance between the recharged and evaporated water. The sharp interface approach assumes the immiscibility of the fluids and thus neglects the mixing between them. As a consequence, for miscible fluids it is more accurate and often needed to use the mixing zone concept, which results from the dynamic equilibrium of flowing freshwater and brine. In this study, we consider two and three-dimensional scale approaches for the management of the mixing zone. The two-dimensional approach is used to understand the dynamics and the characteristics of the salt flat mixing zone, especially in the Salar de Atacama (Atacama salt flat) case. By making use of this model we analyze and quantify the effects of the aquitards on the mixing zone geometry. However, the understanding of the complex physical processes occurring in the salt flats and the management of these environments requires the adoption of three-dimensional regional scale numerical models. The models that take into account the effects of variable density represent the best management tool, but they require large computational resources, especially in the three-dimensional case. In order to avoid these computational limitations in the modeling of salt flats and their valuable ecosystems, we propose a three-step methodology, consisting of: (1) collection, validation and interpretation of the hydrogeochemical data, (2) identification and three-dimensional mapping of the mixing zone on the land surface and in depth, and (3) application of a water head correction to the freshwater and mixed water heads in order to compensate the density variations and to transform them to brine water heads. Finally, an evaluation of the sensibility of the mixing zone to anthropogenic and climate changes is included.

Water exchange, mixing and transient storage between a saturated karstic conduit and the surrounding aquifer: Groundwater flow modeling and inputs from stable water isotopes

NASA Astrophysics Data System (ADS)

Binet, S.; Joigneaux, E.; Pauwels, H.; Albéric, P.; Fléhoc, Ch.; Bruand, A.

2017-01-01

Water exchanges between a karstic conduit and the surrounding aquifer are driven by hydraulic head gradient at the interface between these two domains. The case-study presented in this paper investigates the impact of the geometry and interface conditions around a conduit on the spatial distribution of these exchanges. Isotopic (δ18O and δD), discharge and water head measurements were conducted at the resurgences of a karst system with a strong allogenic recharge component (Val d'Orléans, France), to estimate the amounts of water exchanged and the mixings between a saturated karstic conduit and the surrounding aquifer. The spatio-temporal variability of the observed exchanges was explored using a 2D coupled continuum-conduit flow model under saturated conditions (Feflow®). The inputs from the water heads and stable water isotopes in the groundwater flow model suggest that the amounts of water flowing from the aquifer are significant if the conduit flow discharges are less than the conduit flow capacity. This condition creates a spatial distribution of exchanges from upstream where the aquifer feeds the conduit (recharge area) to downstream where the conduit reaches its maximum discharge capacity and can feed the aquifer (discharge area). In the intermediate transport zone no exchange between the two domains takes place that brings a new criterion to delineate the vulnerable zones to surface water. On average, 4% of the water comes from the local recharge, 80% is recent river water and 16% is old river water. During the November 2008 flood, both isotopic signatures and model suggest that exchanges fluctuate around this steady state, limited when the river water level increases and intensified when the river water level decreases. The existence of old water from the river suggests a transient storage at the aquifer/conduit interface that can be considered as an underground hyporheic zone.

MIRAGE: The data acquisition, analysis, and display system

NASA Technical Reports Server (NTRS)

Rosser, Robert S.; Rahman, Hasan H.

1993-01-01

Developed for the NASA Johnson Space Center and Life Sciences Directorate by GE Government Services, the Microcomputer Integrated Real-time Acquisition Ground Equipment (MIRAGE) system is a portable ground support system for Spacelab life sciences experiments. The MIRAGE system can acquire digital or analog data. Digital data may be NRZ-formatted telemetry packets of packets from a network interface. Analog signal are digitized and stored in experimental packet format. Data packets from any acquisition source are archived to a disk as they are received. Meta-parameters are generated from the data packet parameters by applying mathematical and logical operators. Parameters are displayed in text and graphical form or output to analog devices. Experiment data packets may be retransmitted through the network interface. Data stream definition, experiment parameter format, parameter displays, and other variables are configured using spreadsheet database. A database can be developed to support virtually any data packet format. The user interface provides menu- and icon-driven program control. The MIRAGE system can be integrated with other workstations to perform a variety of functions. The generic capabilities, adaptability and ease of use make the MIRAGE a cost-effective solution to many experimental data processing requirements.

Structural, electronic and chemical properties of metal/oxide and oxide/oxide interfaces and thin film structures

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

Lad, Robert J.

1999-12-14

This project focused on three different aspects of oxide thin film systems: (1) Model metal/oxide and oxide/oxide interface studies were carried out by depositing ultra-thin metal (Al, K, Mg) and oxide (MgO, AlO{sub x}) films on TiO{sub 2}, NiO and {alpha}-Al{sub 2}O{sub 3} single crystal oxide substrates. (2) Electron cyclotron resonance (ECR) oxygen plasma deposition was used to fabricate AlO{sub 3} and ZrO{sub 2} films on sapphire substrates, and film growth mechanisms and structural characteristics were investigated. (3) The friction and wear characteristics of ZrO{sub 2} films on sapphire substrates in unlubricated sliding contact were studied and correlated with filmmore » microstructure. In these studies, thin film and interfacial regions were characterized using diffraction (RHEED, LEED, XRD), electron spectroscopies (XPS, UPS, AES), microscopy (AFM) and tribology instruments (pin-on-disk, friction microprobe, and scratch tester). By precise control of thin film microstructure, an increased understanding of the structural and chemical stability of interface regions and tribological performance of ultra-thin oxide films was achieved in these important ceramic systems.« less

Topology and stability of a water-soybean-oil swirling flow

NASA Astrophysics Data System (ADS)

Carrión, Luis; Herrada, Miguel A.; Shtern, Vladimir N.

2017-02-01

This paper reveals and explains the flow topology and instability hidden in an experimental study by Tsai et al. [Tsai et al., Phys. Rev. E 92, 031002(R) (2015)], 10.1103/PhysRevE.92.031002. Water and soybean oil fill a sealed vertical cylindrical container. The rotating top disk induces the meridional circulation and swirl of both fluids. The experiment shows a flattop interface shape and vortex breakdown in the oil flow developing as the rotation strength R eo increases. Our numerical study shows that vortex breakdown occurs in the water flow at R eo=300 and in the oil flow at R eo=941 . As R eo increases, the vortex breakdown cell occupies most of the water domain and approaches the interface at R eo around 600. The rest of the (countercirculating) water separates from the axis as the vortex breakdown cells in the oil and water meet at the interface-axis intersection. This topological transformation of water flow significantly contributes to the development of the flattop shape. It is also shown that the steady axisymmetric flow suffers from shear-layer instability, which emerges in the water domain at R eo=810 .

Optical methods in fault dynamics

NASA Astrophysics Data System (ADS)

Uenishi, K.; Rossmanith, H. P.

2003-10-01

The Rayleigh pulse interaction with a pre-stressed, partially contacting interface between similar and dissimilar materials is investigated experimentally as well as numerically. This study is intended to obtain an improved understanding of the interface (fault) dynamics during the earthquake rupture process. Using dynamic photoelasticity in conjunction with high-speed cinematography, snapshots of time-dependent isochromatic fringe patterns associated with Rayleigh pulse-interface interaction are experimentally recorded. It is shown that interface slip (instability) can be triggered dynamically by a pulse which propagates along the interface at the Rayleigh wave speed. For the numerical investigation, the finite difference wave simulator SWIFD is used for solving the problem under different combinations of contacting materials. The effect of acoustic impedance ratio of the two contacting materials on the wave patterns is discussed. The results indicate that upon interface rupture, Mach (head) waves, which carry a relatively large amount of energy in a concentrated form, can be generated and propagated from the interface contact region (asperity) into the acoustically softer material. Such Mach waves can cause severe damage onto a particular region inside an adjacent acoustically softer area. This type of damage concentration might be a possible reason for the generation of the "damage belt" in Kobe, Japan, on the occasion of the 1995 Hyogo-ken Nanbu (Kobe) Earthquake.

Experimental investigation of the dynamics of spontaneous pattern formation during dendritic ice crystal growth

NASA Astrophysics Data System (ADS)

Tirmizi, Shakeel H.; Gill, William N.

1989-06-01

The dynamics of spontaneous pattern formation are studied experimentally by observing and recording the evolution of ice crystal patterns which grow freely in a supercooled melt. The sequence of evolution to dendrites is recorded in real time using cine-micrography. In the range of subcoolings from 0.06 to 0.29°C, all the patterns evolved as follows: Smooth disk → Perturbed disk → Disk dendrite → Partially developed dendrite → Fully developed dendrite. The initial smooth disk, the main branch and the side branches all developed perturbations beyond a critical size which depends on the subcooling. The combined effect of the destabilizing thermal gradients ahead of the growing crystal and the stabilizing Gibbs-Thompson capillarity effect dictates the critical size of the unstable structures in terms of the mean curvature of the interface. Detailed analysis of the evolving patterns was done using digital image analysis on the PRIME computer to determine both the manner in which the dendritic growth process replicates itself and the role which the shape and the movement of the interface play in the pattern formation process. Total arc length ST, total area A and the complexity ratio ξ = ST⧸√ A of evolving patterns were computed as a function of time and undercooling for each crystal image. These results permitted us to make some comparisons with theoretical models on pattern evolution. Three distinct phases of evolution were identified: the initial phase when the crystal structure is smooth and free of any perturbations and the complexity ratio is almost a constant, an intermediate phase when the crystal structure develops perturbations which grow quickly in number and in size and the complexity ratio increases rapidly and a final phase when the pattern approaches that of a fully developed dendrite which, on a global scale grows in a shape-perserving manner and has a slowly increasing complexity ratio which seems to approach an asymptote. Two factors were found to be responsible for the symmetric dendritic patterns. These are: first, hexagonal symmetry due to the hexagonal closed packed structure, leads to strong anisotropy in molecular attachment kinetics and in surface free energy; second, the competition among side branches causes smaller side branches to melt when they are trapped between larger ones which generate latent heat and prevent the small branches from gaining access to the fresh cold fluid ahead of them. These two factors lead to a channelling effect which prevents the growth of perturbations from occurring randomly and thus directs the evolving crystal structure into patterns which are regular and reproducible. Theoretical models which are local in nature fail to take into account side branch competition, and this is one of their major weaknesses.

Comets: Role and importance to exobiology

NASA Technical Reports Server (NTRS)

Delsemme, Armand H.

1992-01-01

The transfer of organic compounds from interstellar space to the outskirts of a protoplanetary disk, their accretion into cometary objects, and the transport of the latter into the inner solar system by orbital diffusion throw a new light on the central problem of exobiology. It suggests the existence of a cosmic mechanism, working everywhere, that can supply prebiotic compounds to ubiquitous rocky planets, in search of the proper environment to start life in many places in the Universe. Under the heading of chemistry of the cometary nucleus, the following topics are covered: radial homogeneity of the nucleus; the dust-to-ice ratio; nature of the dust grains; origin of the dust in comets; nature of the volatile fraction; the CO distribution in comet Halley; dust contribution to the volatile fraction; elemental balance sheet of comet Halley; quantitative molecular analysis of the volatile fraction; and isotopic ratios. Under the heading of exogenous origin of carbon on terrestrial planets the following topics are covered: evidence for a high-temperature phase; from planetesimals to planets; a veneer of volatile and organic material; and cometary contribution.

Laser Texturing of Magnetic Recording Media Final Report CRADA No. TSV-1298-96

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

Hackel, L.; Marshall, A.

The Commercial Laser Systems Group at LLNL developed a concept for patterning of computer magnetic recording discs. Magnetic recording media require texturing over areas designated for contact in order to minimize friction with data transducing heads. In fabricating a hard disk, an aluminum nickel-phosphorous substrate was polished to a specular finish then a mechanical means was used to roughen an annular area intended to be the head contact band. In a previous patent (US Patent 5,062,021) it was proposed that the focused output of a low power laser with short pulse length could be used to generate the textured pattern.more » However, the patterned area typically required 75,000 textured spots that needed to be rapidly (less than 10 seconds) printed with good uniformity. A means to achieve the accurate placement and uniform profile, as well as a meaningfully rapid process time, was not discussed in the referenced patent. The LLNL team devised a system that could rapidly and inexpensively accomplish the texturing.« less

Texting while driving using Google Glass™: Promising but not distraction-free.

PubMed

He, Jibo; Choi, William; McCarley, Jason S; Chaparro, Barbara S; Wang, Chun

2015-08-01

Texting while driving is risky but common. This study evaluated how texting using a Head-Mounted Display, Google Glass, impacts driving performance. Experienced drivers performed a classic car-following task while using three different interfaces to text: fully manual interaction with a head-down smartphone, vocal interaction with a smartphone, and vocal interaction with Google Glass. Fully manual interaction produced worse driving performance than either of the other interaction methods, leading to more lane excursions and variable vehicle control, and higher workload. Compared to texting vocally with a smartphone, texting using Google Glass produced fewer lane excursions, more braking responses, and lower workload. All forms of texting impaired driving performance compared to undistracted driving. These results imply that the use of Google Glass for texting impairs driving, but its Head-Mounted Display configuration and speech recognition technology may be safer than texting using a smartphone. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evolution of the head-trunk interface in tetrapod vertebrates

PubMed Central

Sefton, Elizabeth M; Bhullar, Bhart-Anjan S; Mohaddes, Zahra; Hanken, James

2016-01-01

Vertebrate neck musculature spans the transition zone between head and trunk. The extent to which the cucullaris muscle is a cranial muscle allied with the gill levators of anamniotes or is instead a trunk muscle is an ongoing debate. Novel computed tomography datasets reveal broad conservation of the cucullaris in gnathostomes, including coelacanth and caecilian, two sarcopterygians previously thought to lack it. In chicken, lateral plate mesoderm (LPM) adjacent to occipital somites is a recently identified embryonic source of cervical musculature. We fate-map this mesoderm in the axolotl (Ambystoma mexicanum), which retains external gills, and demonstrate its contribution to posterior gill-levator muscles and the cucullaris. Accordingly, LPM adjacent to the occipital somites should be regarded as posterior cranial mesoderm. The axial position of the head-trunk border in axolotl is congruent between LPM and somitic mesoderm, unlike in chicken and possibly other amniotes. DOI: http://dx.doi.org/10.7554/eLife.09972.001 PMID:27090084

Optical information-processing systems and architectures II; Proceedings of the Meeting, San Diego, CA, July 9-13, 1990

NASA Astrophysics Data System (ADS)

Javidi, Bahram

The present conference discusses topics in the fields of neural networks, acoustooptic signal processing, pattern recognition, phase-only processing, nonlinear signal processing, image processing, optical computing, and optical information processing. Attention is given to the optical implementation of an inner-product neural associative memory, optoelectronic associative recall via motionless-head/parallel-readout optical disk, a compact real-time acoustooptic image correlator, a multidimensional synthetic estimation filter, and a light-efficient joint transform optical correlator. Also discussed are a high-resolution spatial light modulator, compact real-time interferometric Fourier-transform processors, a fast decorrelation algorithm for permutation arrays, the optical interconnection of optical modules, and carry-free optical binary adders.

Multiperiod-grating surface-emitting lasers

NASA Technical Reports Server (NTRS)

Lang, Robert J. (Inventor)

1992-01-01

Surface-emitting distributed feedback (DFB) lasers are disclosed with hybrid gratings. A first-order grating is provided at one or both ends of the active region of the laser for retroreflection of light back into the active region, and a second-order or nonresonant grating is provided at the opposite end for coupling light out perpendicular to the surfaces of the laser or in some other selected direction. The gratings may be curved to focus light retroreflected into the active region and to focus light coupled out to a point. When so focused to a point, the DFB laser may be part of a monolithic read head for a laser recorded disk, or an optical coupler into an optical fiber.

Minnealloy: a new magnetic material with high saturation flux density and low magnetic anisotropy

NASA Astrophysics Data System (ADS)

Mehedi, Md; Jiang, Yanfeng; Suri, Pranav Kumar; Flannigan, David J.; Wang, Jian-Ping

2017-09-01

We are reporting a new soft magnetic material with high saturation magnetic flux density, and low magnetic anisotropy. The new material is a compound of iron, nitrogen and carbon, α‧-Fe8(NC), which has saturation flux density of 2.8  ±  0.15 T and magnetic anisotropy of 46 kJ m-3. The saturation flux density is 27% higher than pure iron, a widely used soft magnetic material. Soft magnetic materials are very important building blocks of motors, generators, inductors, transformers, sensors and write heads of hard disk. The new material will help in the miniaturization and efficiency increment of the next generation of electronic devices.

Anomalomermis ephemerophagis n. g., n. sp. (Nematoda: Mermithidae) parasitic in the mayfly Ephemerella maculata Traver (Ephermeroptera: Ephermerellidae) in California, USA.

PubMed

Poinar, George; Walder, Larissa; Uno, Hiromi

2015-03-01

A new nematode, Anomalomermis ephemerophagis n. g., n. sp. (Nematoda: Mermithidae) is described from the mayfly Ephemerella maculata Traver (Ephermeroptera: Ephermerellidae) in California. The new species is characterised by six cephalic papillae and four additional disk papillae located on the head between the cephalic papillae and stoma. Additional diagnostic characters are: a terminal mouth opening; absence of X-fibers in the cuticle of both postparasitic juveniles and adults; paired, curved, medium-sized spicules; a straight barrow-shaped vagina and large eggs. Two infectious agents were present in some specimens. This is the first description of an adult nematode from a mayfly.

Petabyte mass memory system using the Newell Opticel(TM)

NASA Technical Reports Server (NTRS)

Newell, Chester W.

1994-01-01

A random access system is proposed for digital storage and retrieval of up to a Petabyte of user data. The system is comprised of stacked memory modules using laser heads writing to an optical medium, in a new shirt-pocket-sized optical storage device called the Opticel. The Opticel described is a completely sealed 'black box' in which an optical medium is accelerated and driven at very high rates to accommodate the desired transfer rates, yet in such a manner that wear is virtually eliminated. It essentially emulates a disk, but with storage area up to several orders of magnitude higher. Access time to the first bit can range from a few milliseconds to a fraction of a second, with time to the last bit within a fraction of a second to a few seconds. The actual times are dependent on the capacity of each Opticel, which ranges from 72 Gigabytes to 1.25 Terabytes. Data transfer rate is limited strictly by the head and electronics, and is 15 Megabits per second in the first version. Independent parallel write/read access to each Opticel is provided using dedicated drives and heads. A Petabyte based on the present Opticel and drive design would occupy 120 cubic feet on a footprint of 45 square feet; with further development, it could occupy as little as 9 cubic feet.

Social Sciences in Forestry, A Current Selected Bibliography, No. 57. Special Appendix: Theses and Dissertations in Progress.

ERIC Educational Resources Information Center

Schwab, Judith L., Ed.

1982-01-01

Documents which address the interface between forestry and the social sciences comprise this annotated bibliography. A subject-matter classification scheme is used to group publications by subheadings under five major heading: (1) social science applied to forestry at large; (2) applied to forestry's productive agents; (3) applied to forest…

An Inexpensive Autosampler to Maximize Throughput for an Ion Source that Samples Surfaces in Open Air

EPA Science Inventory

An autosampler was built to pull cotton swab heads mounted into a 3-foot long, square Al rod in ambient air through the He ionizing beam of a Direct Analysis in Real Time (DART) ion source interfaced to an orthogonal acceleration, time-of-flight mass spectrometer. The cost of th...

Interface between a printed circuit board computer aided design tool (Tektronix 4051 based) and a numerical paper tape controlled drill press (Slo-Syn 530: 100 w/ Dumore Automatic Head Number 8391)

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

Heckman, B.K.; Chinn, V.K.

1981-01-01

The development and use of computer programs written to produce the paper tape needed for the automation, or numeric control, of drill presses employed to fabricate computed-designed printed circuit boards are described. (LCL)

The allergy and immunology specialist: what is the role in the treatment of skin disease?

PubMed

Charlesworth, Ernest N

2004-10-01

The practice of medicine transcends our neat borders of demarcation between the myriad of medical specialties and medical disciplines. There are no two specialties in which this clinical interface is more blurred than the clinical interface between allergy and dermatology. With a background in both dermatology and allergy, I address where the specialty of allergy/ immunology is heading, as we navigate the coastal waters separating my two primary disciplines. I also discuss the tools traditionally used only in dermatology, which are now being used increasing by a vanguard of allergists to aid in the diagnosis and treatment of allergic skin disease.

Elemental and structural studies at the bone-cartilage interface

NASA Astrophysics Data System (ADS)

Bradley, D. A.; Kaabar, W.; Gundogdu, O.

2012-02-01

The techniques μProton-Induced X-and γ-ray Emission, μ-PIXE and μ-PIGE, were used to investigate trace and essential element distributions in sections of normal and osteoarthritic (OA) human femoral head. μ-PIGE yielded 2-D mappings of Na and F while Ca, Z, P and S were mapped by μ-PIXE. The concentration of chondroitin sulphate supporting functionality in healthy cartilage is significantly reduced in OA samples. Localised Zn points to osteoblastic/osteoclastic activity at the bone-cartilage interface. Small-angle X-ray scattering applied to decalcified OA-affected tissue showed spatial alterations of collagen fibres of decreased axial periodicity compared to normal collagen type I.

Summary of hydrologic testing in Tertiary limestone aquifer, Tenneco offshore exploratory well--Atlantic OCS, lease-block 427 (Jacksonville NH 17-5)

USGS Publications Warehouse

Johnston, Richard H.; Bush, Peter W.; Krause, Richard E.; Miller, James A.; Sprinkle, Craig L.

1982-01-01

A summary of hydrologic testing in an offshore oil-test well (LB427) drilled for Tenneco, Inc., 55 miles east of Fernandina Beach, Florida, is presented. The interval tested (1,050 to 1,070 feet below sea level) is in a calcarenite that is equivalent to the Ocala Limestone (late Eocene) of onshore Florida and South Georgia. At this site the Ocala forms the highly productive Tertiary limestone aquifer system of the southeastern United States. Pressure-head measurements indicate an equivalent freshwater head of 24 to 29 feet above sea level. These pressure-head measurements and an earlier one made in the nearby JOIDES J- I hole are the only hydraulic head determinations to date in the offshore extensions of any of the aquifers underlying the Atlantic coastal plain. A drill-stem test recovered water samples containing about 7,000 milligrams per liter chloride. However, seawater used in the drilling process apparently contaminated the samples and the formation water is considered slightly fresher. The head and salinity data from the Tenneco well suggest that the sampled interval lies in the transition zone between fresh and seawater in the limestone aquifer. These data, when viewed with similar data from JOIDES J-I, show the transition zone to slope very slightly landward. The interface position is probably intermediate between a position compatible with present-day heads and a position compatible with predevelopment heads.

Correlative analysis of head kinematics and brain's tissue response: a computational approach toward understanding the mechanisms of blast TBI

NASA Astrophysics Data System (ADS)

Sarvghad-Moghaddam, H.; Rezaei, A.; Ziejewski, M.; Karami, G.

2017-11-01

Upon impingement of blast waves on the head, stress waves generated at the interface of the skull are transferred into the cranium and the brain tissue and may cause mild to severe blast traumatic brain injury. The intensity of the shock front, defined by the blast overpressure (BoP), that is, the blast-induced peak static overpressure, significantly affects head kinematics as well as the tissue responses of the brain. While evaluation of global linear and rotational accelerations may be feasible, an experimental determination of dynamic responses of the brain in terms of intracranial pressure (ICP), maximum shear stress (MSS), and maximum principal strain (MPS) is almost impossible. The main objective of this study is to investigate possible correlations between head accelerations and the brain's ICP, MSS, and MPS. To this end, three different blasts were simulated by modeling the detonation of 70, 200, and 500 g of TNT at a fixed distance from the head, corresponding to peak BoPs of 0.52, 1.2, and 2 MPa, respectively. A nonlinear multi-material finite element algorithm was implemented in the LS-DYNA explicit solver. Fluid-solid interaction between the blast waves and head was modeled using a penalty-based method. Strong correlations were found between the brain's dynamic responses and both global linear and rotational accelerations at different blast intensities (R^{2 }≥98%), implying that global kinematic parameters of the head might be strong predictors of brain tissue biomechanical parameters.

Shaft/shaft-seal interface characteristics of a multiple disk centrifugal blood pump.

PubMed

Manning, K B; Miller, G E

1999-06-01

A multiple disk centrifugal pump (MDCP) is under investigation as a potential left ventricular assist device. As is the case with most shaft driven pumps, leakage problems around the shaft/shaft seal interface are of major interest. If leakage were to occur during or after implantation, potential events such as blood loss, clotting, blood damage, and/or infections might result in adverse effects for the patient. Because these effects could be quite disastrous, potential shaft and shaft seal materials have been investigated to determine the most appropriate course to limit these effects. Teflon and nylon shaft seals were analyzed as potential candidates along with a stainless steel shaft and a Melonite coated shaft. The materials and shafts were evaluated under various time durations (15, 30, 45, and 60 min), motor speeds (800, 1,000, 1,200, and 1,400 rpm), and outer diameters (1/2 and 3/4 inches). The motor speed and geometrical configurations were typical for the MDCP under normal physiologic conditions. An air and water study was conducted to analyze the inner diameter wear, the inner temperature values, and the outer temperature values. Statistical comparisons were computed for the shaft seal materials, the shafts, and the outer diameters along with the inner and outer temperatures. The conclusions made from the results indicate that both the tested shaft seal materials and shaft materials are not ideal candidates to be used for the MDCP. Teflon experienced a significant amount of wear in air and water studies. Nylon did experience little wear, but heat generation was an evident problem. A water study on nylon was not conducted because of its molecular structure.

DICOM implementation on online tape library storage system

NASA Astrophysics Data System (ADS)

Komo, Darmadi; Dai, Hailei L.; Elghammer, David; Levine, Betty A.; Mun, Seong K.

1998-07-01

The main purpose of this project is to implement a Digital Image and Communications (DICOM) compliant online tape library system over the Internet. Once finished, the system will be used to store medical exams generated from U.S. ARMY Mobile ARMY Surgical Hospital (MASH) in Tuzla, Bosnia. A modified UC Davis implementation of DICOM storage class is used for this project. DICOM storage class user and provider are implemented as the system's interface to the Internet. The DICOM software provides flexible configuration options such as types of modalities and trusted remote DICOM hosts. Metadata is extracted from each exam and indexed in a relational database for query and retrieve purposes. The medical images are stored inside the Wolfcreek-9360 tape library system from StorageTek Corporation. The tape library system has nearline access to more than 1000 tapes. Each tape has a capacity of 800 megabytes making the total nearline tape access of around 1 terabyte. The tape library uses the Application Storage Manager (ASM) which provides cost-effective file management, storage, archival, and retrieval services. ASM automatically and transparently copies files from expensive magnetic disk to less expensive nearline tape library, and restores the files back when they are needed. The ASM also provides a crash recovery tool, which enable an entire file system restore in a short time. A graphical user interface (GUI) function is used to view the contents of the storage systems. This GUI also allows user to retrieve the stored exams and send the exams to anywhere on the Internet using DICOM protocols. With the integration of different components of the system, we have implemented a high capacity online tape library storage system that is flexible and easy to use. Using tape as an alternative storage media as opposed to the magnetic disk has the great potential of cost savings in terms of dollars per megabyte of storage. As this system matures, the Hospital Information Systems/Radiology Information Systems (HIS/RIS) or other components can be developed potentially as interfaces to the outside world thus widen the usage of the tape library system.

The failure analysis and lifetime prediction for the solder joint of the magnetic head

NASA Astrophysics Data System (ADS)

Xiao, Xianghui; Peng, Minfang; Cardoso, Jaime S.; Tang, Rongjun; Zhou, YingLiang

2015-02-01

Micro-solder joint (MSJ) lifetime prediction methodology and failure analysis (FA) are to assess reliability by fatigue model with a series of theoretical calculations, numerical simulation and experimental method. Due to shortened time of solder joints on high-temperature, high-frequency sampling error that is not allowed in productions may exist in various models, including round-off error. Combining intermetallic compound (IMC) growth theory and the FA technology for the magnetic head in actual production, this thesis puts forward a new growth model to predict life expectancy for solder joint of the magnetic head. And the impact of IMC, generating from interface reaction between slider (magnetic head, usually be called slider) and bonding pad, on mechanical performance during aging process is analyzed in it. By further researching on FA of solder ball bonding, thesis chooses AuSn4 growth model that affects least to solder joint mechanical property to indicate that the IMC methodology is suitable to forecast the solder lifetime. And the diffusion constant under work condition 60 °C is 0.015354; the solder lifetime t is 14.46 years.

Eye Tracking and Head Movement Detection: A State-of-Art Survey

PubMed Central

2013-01-01

Eye-gaze detection and tracking have been an active research field in the past years as it adds convenience to a variety of applications. It is considered a significant untraditional method of human computer interaction. Head movement detection has also received researchers' attention and interest as it has been found to be a simple and effective interaction method. Both technologies are considered the easiest alternative interface methods. They serve a wide range of severely disabled people who are left with minimal motor abilities. For both eye tracking and head movement detection, several different approaches have been proposed and used to implement different algorithms for these technologies. Despite the amount of research done on both technologies, researchers are still trying to find robust methods to use effectively in various applications. This paper presents a state-of-art survey for eye tracking and head movement detection methods proposed in the literature. Examples of different fields of applications for both technologies, such as human-computer interaction, driving assistance systems, and assistive technologies are also investigated. PMID:27170851

Learning toward practical head pose estimation

NASA Astrophysics Data System (ADS)

Sang, Gaoli; He, Feixiang; Zhu, Rong; Xuan, Shibin

2017-08-01

Head pose is useful information for many face-related tasks, such as face recognition, behavior analysis, human-computer interfaces, etc. Existing head pose estimation methods usually assume that the face images have been well aligned or that sufficient and precise training data are available. In practical applications, however, these assumptions are very likely to be invalid. This paper first investigates the impact of the failure of these assumptions, i.e., misalignment of face images, uncertainty and undersampling of training data, on head pose estimation accuracy of state-of-the-art methods. A learning-based approach is then designed to enhance the robustness of head pose estimation to these factors. To cope with misalignment, instead of using hand-crafted features, it seeks suitable features by learning from a set of training data with a deep convolutional neural network (DCNN), such that the training data can be best classified into the correct head pose categories. To handle uncertainty and undersampling, it employs multivariate labeling distributions (MLDs) with dense sampling intervals to represent the head pose attributes of face images. The correlation between the features and the dense MLD representations of face images is approximated by a maximum entropy model, whose parameters are optimized on the given training data. To estimate the head pose of a face image, its MLD representation is first computed according to the model based on the features extracted from the image by the trained DCNN, and its head pose is then assumed to be the one corresponding to the peak in its MLD. Evaluation experiments on the Pointing'04, FacePix, Multi-PIE, and CASIA-PEAL databases prove the effectiveness and efficiency of the proposed method.

Towards free 3D end-point control for robotic-assisted human reaching using binocular eye tracking.

PubMed

Maimon-Dror, Roni O; Fernandez-Quesada, Jorge; Zito, Giuseppe A; Konnaris, Charalambos; Dziemian, Sabine; Faisal, A Aldo

2017-07-01

Eye-movements are the only directly observable behavioural signals that are highly correlated with actions at the task level, and proactive of body movements and thus reflect action intentions. Moreover, eye movements are preserved in many movement disorders leading to paralysis (or amputees) from stroke, spinal cord injury, Parkinson's disease, multiple sclerosis, and muscular dystrophy among others. Despite this benefit, eye tracking is not widely used as control interface for robotic interfaces in movement impaired patients due to poor human-robot interfaces. We demonstrate here how combining 3D gaze tracking using our GT3D binocular eye tracker with custom designed 3D head tracking system and calibration method enables continuous 3D end-point control of a robotic arm support system. The users can move their own hand to any location of the workspace by simple looking at the target and winking once. This purely eye tracking based system enables the end-user to retain free head movement and yet achieves high spatial end point accuracy in the order of 6 cm RMSE error in each dimension and standard deviation of 4 cm. 3D calibration is achieved by moving the robot along a 3 dimensional space filling Peano curve while the user is tracking it with their eyes. This results in a fully automated calibration procedure that yields several thousand calibration points versus standard approaches using a dozen points, resulting in beyond state-of-the-art 3D accuracy and precision.

Temperature Dependence of Nonelectrolyte Permeation across Red Cell Membranes

PubMed Central

Galey, W. R.; Owen, J. D.; Solomon, A. K.

1973-01-01

The temperature dependence of permeation across human red cell membranes has been determined for a series of hydrophilic and lipophilic solutes, including urea and two methyl substituted derivatives, all the straight-chain amides from formamide through valeramide and the two isomers, isobutyramide and isovaleramide. The temperature coefficient for permeation by all the hydrophilic solutes is 12 kcal mol-1 or less, whereas that for all the lipophilic solutes is 19 kcal mol-1 or greater. This difference is consonant with the view that hydrophilic molecules cross the membrane by a path different from that taken by the lipophilic ones. The thermodynamic parameters associated with lipophile permeation have been studied in detail. ΔG is negative for adsorption of lipophilic amides onto an oil-water interface, whereas it is positive for transfer of the polar head from the aqueous medium to bulk lipid solvent. Application of absolute reaction rate theory makes it possible to make a clear distinction between diffusion across the water-red cell membrane interface and diffusion within the membrane. Diffusion coefficients and apparent activation enthalpies and entropies have been computed for each process. Transfer of the polar head from the solvent into the interface is characterized by ΔG ‡ = 0 kcal mol-1 and ΔS ‡ negative, whereas both of these parameters have large positive values for diffusion within the membrane. Diffusion within the membrane is similar to what is expected for diffusion through a highly associated viscous fluid. PMID:4708405

Impact of magnetic fields on ram pressure stripping in disk galaxies

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

Ruszkowski, M.; Brüggen, M.; Lee, D.

Ram pressure stripping can remove significant amounts of gas from galaxies in clusters and massive groups and thus has a large impact on the evolution of cluster galaxies. Recent observations have shown that key properties of ram-pressure-stripped tails of galaxies, such as their width and structure, are in conflict with predictions by simulations. To increase the realism of existing simulations, we simulated for the first time a disk galaxy exposed to a uniformly magnetized wind including radiative cooling and self-gravity of the gas. We find that magnetic fields have a strong effect on the morphology of the gas in themore » tail of the galaxy. While in the purely hydrodynamical case the tail is very clumpy, the magnetohydrodynamical case shows very filamentary structures in the tail. The filaments can be strongly supported by magnetic pressure and, wherever this is the case, the magnetic fields vectors tend to be aligned with the filaments. The ram pressure stripping process may lead to the formation of magnetized density tails that appear as bifurcated in the plane of the sky and resemble the double tails observed in ESO 137-001 and ESO 137-002. Such tails can be formed under a variety of situations, both for the disks oriented face-on with respect to the intracluster medium (ICM) wind and for the tilted ones. While this bifurcation is the consequence of the generic tendency for the magnetic fields to produce very filamentary tail morphology, the tail properties are further shaped by the combination of the magnetic field orientation and the sliding of the field past the disk surface exposed to the wind. Despite the fact that the effect of the magnetic field on the morphology of the tail is strong, magnetic draping does not strongly change the rate of gas stripping. For a face-on galaxy, the field tends to reduce the amount of gas stripping compared to the pure hydrodynamical case, and is associated with the formation of a stable magnetic draping layer on the side of the galaxy exposed to the incoming ICM wind. For significantly tilted disks, the situation may be reversed and the stripping rate may be enhanced by the 'scraping' of the disk surface by the magnetic fields sliding past the ISM/ICM interface. Instabilities, such as gravitational instabilities, undo the protective effect of this layer and allow the gas to leak out of the galaxy.« less

Study of Shell-Mold Thermal Resistance: Laboratory Measurements, Estimation from Compact Strip Production Plant Data, and Observation of Simulated Flux-Mold Interface

NASA Astrophysics Data System (ADS)

González de la C., J. Manuel; Flores F., Tania M.; Castillejos E., A. Humberto

2016-08-01

The slag film that forms between the shell and mold in steel continuous casting is key in regulating the heat transfer between them. Generally, the mechanisms proposed are related to the phenomena associated with the formation of crystals in the solid layer of the film, such as the appearance of internal pores and surface roughness, which decrease phononic conduction through the layer and interfacial gap with the mold, respectively, and the emergence of crystals themselves, which reduce the transmissivity of infrared radiation across the layer. Due to the importance of the solid layer, this study investigates experimentally the effective thermal resistance, R T, between a hot Inconel surface and a cold Cu surface separated by an initially glassy slag disk, made from powders for casting low and medium-carbon steels, denoted as A and B, respectively. In the tests, an initially mirror-polished disk is sandwiched for 10,800 seconds while the Inconel temperature, away from the disk face, is maintained steady at a value, T c, between 973 K and 1423 K (700 °C and 1150 °C)-below the liquidus temperature of the slags. The disks have a thickness, d t, between ~0.7 and 3.2 mm. Over the range of conditions studied, mold slag B shows R T 33 pct larger than slag A, and microscopic observation of disks hints that the greater resistance arises from the larger porosity developed in B. This finding is supported by high-temperature confocal laser scanning microscope observations of the evolution of the surface of slag parallelepipeds encased between Pt sheets, which reveal that during devitrification the film surface moves outward not inward, contrary with what is widely claimed. This behavior would favor contact of the slag with the mold for both kinds of powders. However, in the case of slag A, the crystalline grains growing at or near the surface pack closely together, leaving only few and small empty spaces. In slag B, crystalline grains pack loosely and many and large empty spaces arise in and below the surface. Estimation from plant data shows R T values smaller than measured ones, suggesting that the process film slag thickness must be considerably thinner than those of laboratory disks. However, the difference in thermal resistance of both powders, averaged over the mold length, is close to the dissimilarity found in laboratory.

In search of rules behind environmental framing; the case of head pitch.

PubMed

Wilson, Gwendoline Ixia; Norman, Brad; Walker, James; Williams, Hannah J; Holton, M D; Clarke, D; Wilson, Rory P

2015-01-01

Whether, and how, animals move requires them to assess their environment to determine the most appropriate action and trajectory, although the precise way the environment is scanned has been little studied. We hypothesized that head attitude, which effectively frames the environment for the eyes, and the way it changes over time, would be modulated by the environment. To test this, we used a head-mounted device (Human-Interfaced Personal Observation platform - HIPOP) on people moving through three different environments; a botanical garden ('green' space), a reef ('blue' space), and a featureless corridor, to examine if head movement in the vertical axis differed between environments. Template matching was used to identify and quantify distinct behaviours. The data on head pitch from all subjects and environments over time showed essentially continuous clear waveforms with varying amplitude and wavelength. There were three stylised behaviours consisting of smooth, regular peaks and troughs in head pitch angle and variable length fixations during which the head pitch remained constant. These three behaviours accounted for ca. 40 % of the total time, with irregular head pitch changes accounting for the rest. There were differences in rates of manifestation of behaviour according to environment as well as environmentally different head pitch values of peaks, troughs and fixations. Finally, although there was considerable variation in head pitch angles, the peak and trough values bounded most of the variation in the fixation pitch values. It is suggested that the constant waveforms in head pitch serve to inform people about their environment, providing a scanning mechanism. Particular emphasis to certain sectors is manifest within the peak and trough limits and these appear modulated by the distribution of the points where fixation, interpreted as being due to objects of interest, occurs. This behaviour explains how animals allocate processing resources to the environment and shows promise for movement studies attempting to elucidate which parts of the environment affect movement trajectories.

Simulating the frontal instability of lock-exchange density currents with dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Li, Yanggui; Geng, Xingguo; Wang, Heping; Zhuang, Xin; Ouyang, Jie

2016-06-01

The frontal instability of lock-exchange density currents is numerically investigated using dissipative particle dynamics (DPD) at the mesoscopic particle level. For modeling two-phase flow, the “color” repulsion model is adopted to describe binary fluids according to Rothman-Keller method. The present DPD simulation can reproduce the flow phenomena of lock-exchange density currents, including the lobe-and-cleft instability that appears at the head, as well as the formation of coherent billow structures at the interface behind the head due to the growth of Kelvin-Helmholtz instability. Furthermore, through the DPD simulation, some small-scale characteristics can be observed, which are difficult to be captured in macroscopic simulation and experiment.

The influence of corneal astigmatism on retinal nerve fiber layer thickness and optic nerve head parameter measurements by spectral-domain optical coherence tomography

PubMed Central

2012-01-01

Background To evaluate the influence of corneal astigmatism (CA) on retinal nerve fiber layer (RNFL) thickness and optic nerve head(ONH) parameters measured with spectral-domain optical coherence tomography (OCT) in high myopes patients before refractive surgery. Methods Seventy eyes of 35 consecutive refractive surgery candidates were included in this study. The mean age of the subjects was 26.42 ± 6.95 years, the average CA was −1.17 diopters (D; SD 0.64; range −0.2 to-3.3D), All subjects in this study were WTR CA. 34 eyes were in the normal CA group with a mean CA was −0.67 ± 0.28D, 36 eyes were in the high CA group with an average CA of −1.65 ± 0.49D. All subjects underwent ophthalmic examination and imaging with the Cirrus HD OCT. Results No significant difference was noted in the average cup-to-disk ratio, vertical cup-to-disk ratio and cup volume (all P values > 0.05). Compared with the normal CA group, the high CA group had a larger disc area and rim area, thinner RNFL thickness in the temporal quadrant, and the superotemporal and inferotemporal peaks were farther to the temporal horizon (All P values < 0.05). There were no significant differences between the two groups in global average RNFL thickness, as well as superior, nasal and inferior quadrant RNFL thickness (all P values > 0.05). Conclusions The degree of with-the-rule CA should be considered when interpreting ONH parameters and peripapillary RNFL thickness measured by the Cirrus HD OCT. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1148475676881895 PMID:22621341

Cannibalization of Dwarf Galaxies by the Milky Way: Distance to the Leading Arm of the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Antwi-Danso, Jacqueline; Barger, Kathleen; Haffner, L. Matthew

2016-01-01

Tidal interactions between two dwarf galaxies near the Milky Way, the Large and Small Magellanic Clouds, have caused large quantities of gas to be flung into the halo of the Milky Way. Much of this tidal debris, known as the Magellanic System, is currently headed towards the disk of the Milky Way, spearheaded by the Leading Arm, with the Bridge connecting the two dwarf galaxies, and the trailing Magellanic Stream at the end. Estimates for the amount of gas that the Magellanic System contains are in the range of (2 - 4) × 109 M⊙ and this could supply our Galaxy with (3.7 - 6.7) M⊙ yr-1 (Fox et al. 2014). Although this is higher than the present star-formation rate of the Galaxy, the position of the tidal debris predisposes it to ionizing radiation from the extragalactic background and Galactic disk, as well as ram-pressure stripping from the halo, hindering gas accretion. Some parts of the Leading Arm, however, appear to have already survived the trip to the disk as their morphology is indicative of interaction with the interstellar medium of the Galaxy. The exact amount of gas that this structure contains is uncertain because of weak constrains in its distance. In this study, we made seven pointed Hα observations using the Wisconsin Hα Mapper Telescope and then compared the Hα intensity we obtained to models of the anticipated ionizing flux from the Milky Way and extragalactic background. From this, we calculated the distance from the Sun to the Leading Arm of the Magellanic System at the locations of our observations.

Seeing Red in NGC 1978, NGC 55, and NGC 3109

NASA Astrophysics Data System (ADS)

Davidge, T. J.

2018-04-01

Spectra of the intermediate-age star cluster NGC 1978 and the dwarf irregular galaxies NGC 55 and NGC 3109 are discussed. The spectra were recorded with the Gemini Multi-object Spectrograph on Gemini South and span the 0.7–1.1 μm wavelength interval. Five slit pointings were observed in NGC 1978, and these are used to examine stochastic effects on the integrated red light from an intermediate-age cluster. The removal of either the brightest M giant or the brightest C star from the co-added spectrum has minor effects on the equivalent withs of the Ca triplet. The most robust signature of C stars in the integrated cluster spectrum at these wavelengths is the CN band head near 7900 Å. The equivalent widths of Ca triplet lines in the NGC 1978 spectrum and in the spectra of individual cluster stars are larger than expected for a scaled-solar abundance system. It is suggested that these stars have a lower than expected surface gravity, which might occur if the stars in NGC 1978 have been subject to extra mixing processes, as suggested by Lederer et al. The near-infrared color profile of NGC 1978 is shown to contain a prominent red cusp in the central 10 arcsec, and the suppression of light from this cusp does not affect the depth of the Ca lines in the integrated spectrum. The NGC 55 spectra run parallel to the major axis, and a gradient is found in the strength of the Ca lines, in the sense that the Ca lines weaken with increasing distance from the disk plane. Comparisons with models suggest that the disk light is dominated by stars with ages 1–2 Gyr, in agreement with star-forming histories (SFHs) obtained from the analysis of color–magnitude diagrams (CMDs). The NGC 55 spectra also sample a large star-forming complex. The age of this complex inferred from comparisons with models is broadly consistent with that estimated from a near-infrared CMD of the same region. The CN band head at 7900 Å in this part of NGC 55 is detected, but this is likely a signature of red supergiants (RSGs) rather than C stars. The NGC 3109 observations sample three different parts of that galaxy but have a low signal-to-noise ratio. Comparisons with models suggest that the light from the NGC 3109 disk at red wavelengths is dominated by RSGs with ages of at most a few tens of Myr, in qualitative agreement with SFHs that are based on photometric measurements.

WFIRST: Coronagraph Systems Engineering and Performance Budgets

NASA Astrophysics Data System (ADS)

Poberezhskiy, Ilya; cady, eric; Frerking, Margaret A.; Kern, Brian; Nemati, Bijan; Noecker, Martin; Seo, Byoung-Joon; Zhao, Feng; Zhou, Hanying

2018-01-01

The WFIRST coronagraph instrument (CGI) will be the first in-space coronagraph using active wavefront control to directly image and characterize mature exoplanets and zodiacal disks in reflected starlight. For CGI systems engineering, including requirements development, CGI performance is predicted using a hierarchy of performance budgets to estimate various noise components — spatial and temporal flux variations — that obscure exoplanet signals in direct imaging and spectroscopy configurations. These performance budgets are validated through a robust integrated modeling and testbed model validation efforts.We present the performance budgeting framework used by WFIRST for the flow-down of coronagraph science requirements, mission constraints, and observatory interfaces to measurable instrument engineering parameters.

An accelerated forth data-acquisition system

NASA Technical Reports Server (NTRS)

Bowhill, S. A.; Rennier, A. D.

1986-01-01

A new data acquisition system was put into operation at Urbana in August 1984. It uses a standard Apple 2 microcomputer with 48 k RAM and a standard 5 1/4 inch floppy disk. Design criteria for the system is given. The system was implemented using fig-FORTH, a threaded interpretive language which permits easy interfacing to machine code. The throughput of this system is better by a factor of 6 than the PDP-15 minicomputer system previously used, and it has the real time display feature and provides the data in much more convenient form. The features which contribute to this improved performance is listed.