Prompt Neutron Time Decay in Single HEU and DU Metal Annular Storage Castings

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

Pena, Kirsten E; McConchie, Seth M; Mihalczo, John T

2010-01-01

Previous measurements of highly enriched uranium (HEU) storage castings performed by Oak Ridge National Laboratory (ORNL) at the Y-12 National Security Complex showed a prompt neutron time decay that is not exponential. These measurements showed that multiple time constants originating from multiplication, time-of-flight, scattering in the assembly and room return could be associated with this prompt neutron decay. In this work, the contribution not associated with neutron multiplication was investigated via measurements with a depleted uranium (DU) casting. The measurements at ORNL used an annular (5.0-in OD, 3.5-in ID, 6.0-in H) DU casting with a time-tagged 252Cf source, centered verticallymore » on the axis, and four closely coupled 1 1 6-in.-long plastic scintillators with -in.- thick lead shielding adjacent to the outer surface of the casting. This setup was identical to the configuration used in the previously performed measurements with HEU castings at Y-12. The time correlation between fission events and detections in the plastic scintillators was measured, as well as the time distribution of coincidences between multiple detectors within a 512-ns time window. The measurement results were then compared to MCNP-PoliMi calculations and the previous HEU measurements. Time constants from decay fits to the HEU and DU data were compared to characterize the contributions resulting from multiplication, time-of-flight, and scattering.« less

High Pressure Rotary Shaft Sealing Mechanism

DOEpatents

Dietle, Lannie; Gobeli, Jeffrey D.

2001-05-08

A laterally translatable pressure staged rotary shaft sealing mechanism having a seal housing with a shaft passage therein being exposed to a fluid pressure P1 and with a rotary shaft being located within the shaft passage. At least one annular laterally translatable seal carrier is provided. First and second annular resilient sealing elements are supported in axially spaced relation by the annular seal carriers and have sealing relation with the rotary shaft. The seal housing and at least one seal carrier define a first pressure staging chamber exposed to the first annular resilient sealing element and a second pressure staging chamber located between and exposed to the first and second annular resilient sealing elements. A first fluid is circulated to the first pressure chamber at a pressure P1, and a second staging pressure fluid is circulated to the second pressure chamber at a fraction of pressure P1 to achieve pressure staging, cooling of the seals. Seal placement provides hydraulic force balancing of the annular seal carriers.

Annular solid-immersion lenslet array super-resolution optical microscopy

NASA Astrophysics Data System (ADS)

Liau, Z. L.

2012-10-01

We describe a novel solid-immersion lenslet array, micro-fabricated in a chip form in the high-index (3.45) gallium phosphide. The innovatively designed lenslet features an annular aperture with appropriately patterned light absorbers and antireflection coatings. The array chip is easy to handle and enables the direct deposition of the specimen of interest onto its back-plane for tight adhesion and good optical coupling. The ensuing diffraction from the near field can yield supercritical rays inside the high-index lenslet and can, therefore, overcome the refraction and critical-angle limitations. This model showed agreement with the experimental observation of the solid-immersion fluorescence microscopy imaging, in which the refracted rays were completely blocked by the annular aperture. A large longitudinal (depth) magnification effect was also predicted and showed agreement with experiment. The annular lenslet's additional advantages of improved resolution and contrast were also discussed. Resolution of nested-L patterns with grating pitch as small as 100 nm was experimentally demonstrated. The demonstrated annular solid-immersion lenslet array concept is promising for a wider use in super-resolution optical microscopy.

Fusion reactor pumped laser

DOEpatents

Jassby, D.L.

1987-09-04

A nuclear pumped laser capable of producing long pulses of very high power laser radiation is provided. A toroidal fusion reactor provides energetic neutrons which are slowed down by a moderator. The moderated neutrons are converted to energetic particles capable of pumping a lasing medium. The lasing medium is housed in an annular cell surrounding the reactor. The cell includes an annular reflecting mirror at the bottom and an annular output window at the top. A neutron reflector is disposed around the cell to reflect escaping neutrons back into the cell. The laser radiation from the annular window is focused onto a beam compactor which generates a single coherent output laser beam. 10 figs.

Fusion reactor pumped laser

DOEpatents

Jassby, Daniel L.

1988-01-01

A nuclear pumped laser capable of producing long pulses of very high power laser radiation is provided. A toroidal fusion reactor provides energetic neutrons which are slowed down by a moderator. The moderated neutrons are converted to energetic particles capable of pumping a lasing medium. The lasing medium is housed in an annular cell surrounding the reactor. The cell includes an annular reflecting mirror at the bottom and an annular output window at the top. A neutron reflector is disposed around the cell to reflect escaping neutrons back into the cell. The laser radiation from the annular window is focused onto a beam compactor which generates a single coherent output laser beam.

PLASMA DEVICE

DOEpatents

Baker, W.R.; Brathenahl, A.; Furth, H.P.

1962-04-10

A device for producing a confined high temperature plasma is described. In the device the concave inner surface of an outer annular electrode is disposed concentrically about and facing the convex outer face of an inner annular electrode across which electrodes a high potential is applied to produce an electric field there between. Means is provided to create a magnetic field perpendicular to the electric field and a gas is supplied at reduced pressure in the area therebetween. Upon application of the high potential, the gas between the electrodes is ionized, heated, and under the influence of the electric and magnetic fields there is produced a rotating annular plasma disk. The ionized plasma has high dielectric constant properties. The device is useful as a fast discharge rate capacitor, in controlled thermonuclear research, and other high temperature gas applications. (AEC)

Levitation pressure and friction losses in superconducting bearings

DOEpatents

Hull, John R.

2001-01-01

A superconducting bearing having at least one permanent magnet magnetized with a vertical polarization. The lower or stator portion of the bearing includes an array of high-temperature superconducting elements which are comprised of a plurality of annular rings. An annular ring is located below each permanent magnet and an annular ring is offset horizontally from at least one of the permanent magnets. The rings are composed of individual high-temperature superconducting elements located circumferentially along the ring. By constructing the horizontally-offset high-temperature superconducting ring so that the c-axis is oriented in a radial direction, a higher levitation force can be achieved. Such an orientation will also provide substantially lower rotational drag losses in the bearing.

A novel HTS magnetic levitation dining table

NASA Astrophysics Data System (ADS)

Lu, Yiyun; Huang, Huiying

2018-05-01

High temperature superconducting (HTS) bulk can levitate above or suspend below a permanent magnet stably. Many magnificent potential applications of HTS bulk are proposed by researchers. Until now, few reports have been found for real applications of HTS bulk. A complete set of small-scale HTS magnetic levitation table is proposed in the paper. The HTS magnetic levitation table includes an annular HTS magnetic levitation system which is composed of an annular HTS bulk array and an annular permanent magnet guideway (PMG). The annular PMG and the annular cryogenics vessel which used to maintain low temperature environment of the HTS bulk array are designed. 62 YBCO bulks are used to locate at the bottom of the annular vessel. A 3D-model finite element numerical method is used to design the HTS bulk magnetic levitation system. Equivalent magnetic levitation and guidance forces calculation rules are proposed aimed at the annular HTS magnetic levitation system stability. Based on the proposed method, levitation and guidance forces curves of the one YBCO bulk magnetic above PMG could be obtained. This method also can use to assist PMG design to check whether the designed PMG could reach the basic demand of the HTS magnetic levitation table.

Diagnosis of the influence of the solar cycle in the annular character of the NAM using RAM.

NASA Astrophysics Data System (ADS)

de La Torre, L.; Gimeno, L.; Tesouro, M.; Nieto, R.; Añel, J. A.; Ribera, P.; García, R.; Hernández, E.

2003-04-01

It has been suggested that the North Atlantic Oscillation is a regional expression of the so called Northern Hemisphere Annular Mode (NAM), although some evidences have been found against this hypothesis. However, recent studies conect the spatial structure of the NAM with the phase of solar cycle, being annular-like only for the periods of high solar activity. With this work we try to make a contribution to the debate by using atmospheric relative angular momentum (RAM) to diagnose the annular character of the mode. Correlations of RAM vs. temperature and geopotential height at different levels for high activity years show a more zonally extended pattern than those for low activity years. Moreover, the Atlantic pattern is always shown, even when using RAM computed by 60º longitude sectors. On the other hand, the Pacific pattern almost dissapear.

Effect of a semi-annular thermal acoustic shield on jet exhaust noise

NASA Technical Reports Server (NTRS)

Goodykoontz, J.

1980-01-01

Reductions in jet exhaust noise obtained by the use of an annular thermal acoustic shield consisting of a high temperature, low velocity gas stream surrounding a high velocity central jet exhaust appear to be limited by multiple reflections. The effect of a semi-annular shield on jet exhaust noise was investigted with the rationale that such a configuration would eliminate or reduce the multiple reflection mechanism. Noise measurements for a 10 cm conical nozzle with a semi-annular acoustic shield are presented in terms of lossless free field data at various angular locations with respect to the nozzle. Measurements were made on both the shielded and unshielded sides of the nozzle. The results are presented parametrically, showing the effects of various shield and central system velocities and temperatures. Selected results are scaled up to a typical full scale engine size to determine the perceived noise level reductions.

FUEL ASSAY REACTOR

DOEpatents

Spinrad, B.I.; Sandmeier, H.A.; Martens, F.H.

1962-12-25

A reactor having maximum sensitivity to perturbations is described comprising a core consisting of a horizontally disposed, rectangular, annular fuel zone containing enriched uranium dioxide dispersed in graphite, the concentration of uranium dioxide increasing from the outside to the inside of the fuel zone, an internal reflector of graphite containing an axial test opening disposed within the fuel zone, an external graphite reflector, means for changing the neutron spectrum in the test opening, and means for measuring perturbations in the neutron flux caused by the introduction of different fuel elements into the test opening. (AEC)

Tricuspid Annular Geometry: A Three-Dimensional Transesophageal Echocardiographic Study

PubMed Central

Mahmood, Feroze; Kim, Han; Chaudary, Bilal; Bergman, Remco; Matyal, Robina; Gerstle, Jeniffer; Gorman, Joseph H.; Gorman, Robert C.; Khabbaz, Kamal R.

2013-01-01

Objective To demonstrate the clinical feasibility of accurately measuring tricuspid annular area by 3-dimensional (3D) transesophageal echocardiography (TEE) and to assess the geometric differences based on the presence of tricuspid regurgitation (TR). Also, the shape of the tricuspid annulus was compared with previous descriptions in the literature. Design Prospective. Setting Tertiary care university hospital. Interventions Three-dimensional TEE. Participants Patients undergoing cardiac surgery. Measurements and Main Results Volumetric data sets from 20 patients were acquired by 3D TEE and prospectively analyzed. Comparisons in annular geometry were made between groups based on the presence of TR. The QLab (Philips Medical Systems, Andover, MA) software package was used to calculate tricuspid annular area by both linear elliptical dimensions and planimetry. Further analyses were performed in the 4D Cardio-View (TomTec Corporation GmBH, Munich, Germany) and MATLAB (Natick, MA) software environments to accurately assess annular shape. It was found that patients with greater TR had an eccentrically dilated annulus with a larger annular area. Also, the area as measured by the linear ellipse method was overestimated as compared to the planimetry method. Furthermore, the irregular saddle-shaped geometry of the tricuspid annulus was confirmed through the mathematic model developed by the authors. Conclusions Three-dimensional TEE can be used to measure the tricuspid annular area in a clinically feasible fashion, with an eccentric dilation seen in patients with TR. The tricuspid annulus shape is complex, with annular high and low points, and annular area calculation based on linear measurements significantly overestimates 3D planimetered area. PMID:23725682

Radial electron-beam-breakup transit-time oscillator

DOEpatents

Kwan, Thomas J. T.; Mostrom, Michael A.

1998-01-01

A radial electron-beam-breakup transit-time oscillator (RBTO) provides a compact high power microwave generator. The RBTO includes a coaxial vacuum transmission line having an outer conductor and an inner conductor. The inner conductor defines an annular cavity with dimensions effective to support an electromagnetic field in a TEM.sub.00m mode. A radial field emission cathode is formed on the outer conductor for providing an electron beam directed toward the annular cavity electrode. Microwave energy is then extracted from the annular cavity electrode.

Distinct Annular Oligomers Captured along the Assembly and Disassembly Pathways of Transthyretin Amyloid Protofibrils

PubMed Central

Pires, Ricardo H.; Karsai, Árpád; Saraiva, Maria J.; Damas, Ana M.; Kellermayer, Miklós S. Z.

2012-01-01

Background Defects in protein folding may lead to severe degenerative diseases characterized by the appearance of amyloid fibril deposits. Cytotoxicity in amyloidoses has been linked to poration of the cell membrane that may involve interactions with amyloid intermediates of annular shape. Although annular oligomers have been detected in many amyloidogenic systems, their universality, function and molecular mechanisms of appearance are debated. Methodology/Principal Findings We investigated with high-resolution in situ atomic force microscopy the assembly and disassembly of transthyretin (TTR) amyloid protofibrils formed of the native protein by pH shift. Annular oligomers were the first morphologically distinct intermediates observed in the TTR aggregation pathway. Morphological analysis suggests that they can assemble into a double-stack of octameric rings with a 16±2 nm diameter, and displaying the tendency to form linear structures. According to light scattering data coupled to AFM imaging, annular oligomers appeared to undergo a collapse type of structural transition into spheroid oligomers containing 8–16 monomers. Disassembly of TTR amyloid protofibrils also resulted in the rapid appearance of annular oligomers but with a morphology quite distinct from that observed in the assembly pathway. Conclusions/Significance Our observations indicate that annular oligomers are key dynamic intermediates not only in the assembly but also in the disassembly of TTR protofibrils. The balance between annular and more compact forms of aggregation could be relevant for cytotoxicity in amyloidogenic disorders. PMID:22984597

Stability of Mars' annular polar vortex

NASA Astrophysics Data System (ADS)

Seviour, W.; Waugh, D.; Scott, R.

2016-12-01

In common with the Earth and several other planetary bodies, the martian atmosphere exhibits regions of high potential vorticity (PV) near the winter pole, known as polar vortices. On Earth, PV increases monotonically from the equator to pole, however, on Mars there is a local minimum at the pole, with an annulus of high PV encircling it. Recently produced reanalyses of the martian atmospheric circulation have confirmed that this annular vortex is a persistent feature, forming in autumn and lasting until spring. This finding is surprising since an isolated band of PV is barotropically unstable, a result going back to Rayleigh. Here we investigate the stability of an annular vortex using numerical integrations of the rotating shallow water equations. We show that the mode of instability and its growth rate strongly depends upon the latitude and width of the annulus. By introducing thermal relaxation with a time scale similar to that of the instability we are able to simulate a persistent annular vortex with similar characteristics as that observed in the martian atmosphere. This time scale, typically 1-2 sols, is similar to thermal relaxation timescales which have been estimated for the martian atmosphere. We also demonstrate that the persistence of an annular vortex is robust to topographic forcing, as long as it is below a certain amplitude. We hence propose that the persistence of this barotropically unstable annular vortex is permitted due to the combination of short radiative relaxation time scales and relatively weak topographic forcing in the martian polar atmosphere.

Impact of Annular Size on Outcomes After Surgical or Transcatheter Aortic Valve Replacement.

PubMed

Deeb, G Michael; Chetcuti, Stanley J; Yakubov, Steven J; Patel, Himanshu J; Grossman, P Michael; Kleiman, Neal S; Heiser, John; Merhi, William; Zorn, George L; Tadros, Peter N; Petrossian, George; Robinson, Newell; Mumtaz, Mubashir; Gleason, Thomas G; Huang, Jian; Conte, John V; Popma, Jeffrey J; Reardon, Michael J

2018-04-01

This analysis evaluates the relationship of annular size to hemodynamics and the incidence of prosthesis-patient mismatch (PPM) in surgical aortic valve replacement (SAVR) and transcatheter aortic valve replacement (TAVR) patients. The CoreValve US Pivotal High Risk Trial, described previously, compared TAVR using a self-expanding valve with SAVR. Multislice computed tomography was used to categorize TAVR and SAVR subjects according to annular perimeter-derived diameter: large (≥26 mm), medium (23 to <26 mm), and small (<23 mm). Hemodynamics, PPM, and clinical outcomes were assessed. At all postprocedure visits, mean gradients were significantly lower for TAVR compared with SAVR in small and medium size annuli (p < 0.001). Annular size was significantly associated with mean gradient after SAVR, with small annuli having the highest gradients (p < 0.05 at all timepoints); gradients were similar across all annular sizes after TAVR. In subjects receiving SAVR, the frequency of PPM was significantly associated with annular size, with small annuli having the greatest incidence. No difference in PPM incidence by annular sizing was observed with TAVR. In addition, TAVR subjects had significantly less PPM than SAVR subjects in small and medium annuli (p < 0.001), with no difference in the incidence of PPM between TAVR and SAVR in large annuli (p = 0.10). Annular size has a significant effect on hemodynamics and the incidence of PPM in SAVR subjects, not observed in TAVR subjects. With respect to annular size, TAVR results in better hemodynamics and less PPM for annuli less than 26 mm and should be strongly considered when choosing a tissue valve for small and medium size annuli. Copyright © 2018 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

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

Matsutani, Takaomi; Taya, Masaki; Ikuta, Takashi

A parallel image detection system using an annular pupil for electron optics were developed to realize an increase in the depth of focus, aberration-free imaging and separation of amplitude and phase images under scanning transmission electron microscopy (STEM). Apertures for annular pupils able to suppress high-energy electron scattering were developed using a focused ion beam (FIB) technique. The annular apertures were designed with outer diameter of oe 40 {mu}m and inner diameter of oe32 {mu}m. A taper angle varying from 20 deg. to 1 deg. was applied to the slits of the annular apertures to suppress the influence of high-energymore » electron scattering. Each azimuth angle image on scintillator was detected by a multi-anode photomultiplier tube assembly through 40 optical fibers bundled in a ring shape. To focus the image appearing on the scintillator on optical fibers, an optical lens relay system attached with CCD camera was developed. The system enables the taking of 40 images simultaneously from different scattered directions.« less

Research on Annular Frictional Pressure Loss of Hydraulic-Fracturing in Buckling Coiled Tubing

NASA Astrophysics Data System (ADS)

Liu, Bin; Cai, Meng; Li, Junliang; Xu, Yongquan; Wang, Peng

2018-01-01

Compared with conventional hydraulic fracturing, coiled tubing (CT) annular delivery sand fracturing technology is a new method to enhance the recovery ratio of low permeability reservoir. Friction pressure loss through CT has been a concern in fracturing. The small diameter of CT limits the cross-sectional area open to flow, therefore, to meet large discharge capacity, annular delivery sand technology has been gradually developed in oilfield. Friction pressure is useful for determining the required pump horsepower and fracturing construction design programs. Coiled tubing can buckle when the axial compressive load acting on the tubing is greater than critical buckling load, then the geometry shape of annular will change. Annular friction pressure loss elevates dramatically with increasing of discharge capacity, especially eccentricity and CT buckling. Despite the frequency occurrence of CT buckling in oilfield operations, traditionally annular flow frictional pressure loss considered concentric and eccentric annuli, not discussing the effects of for discharge capacity and sand ratio varying degree of CT buckling. The measured data shows that the factors mentioned above cannot be ignored in the prediction of annular pressure loss. It is necessary to carry out analysis of annulus flow pressure drop loss in coiled tubing annular with the methods of theoretical analysis and numerical simulation. Coiled tubing buckling has great influence on pressure loss of fracturing fluid. Therefore, the correlations have been developed for turbulent flow of Newtonian fluids and Two-phase flow (sand-liquid), and that improve the friction pressure loss estimation in coiled tubing operations involving a considerable level of buckling. Quartz sand evidently increases pressure loss in buckling annular, rising as high as 40%-60% more than fresh water. Meanwhile, annulus flow wetted perimeter increases with decreasing helical buckling pitch of coiled tubing, therefore, the annulus flow frictional pressure loss rapidly increases with decreasing helical buckling pitch. The research achievement provides theoretical guidance for coiled tubing annular delivery sand fracturing operation and design.

Annular Seals of High Energy Centrifugal Pumps: Presentation of Full Scale Measurement

NASA Technical Reports Server (NTRS)

Florjancic, S.; Stuerchler, R.; Mccloskey, T.

1991-01-01

Prediction of rotordynamic behavior for high energy concentration centrifugal pumps is a challenging task which still imposes considerable difficulties. While the mechanical modeling of the rotor is solved most satisfactorily by finite element techniques, accurate boundary conditions for arbitrary operating conditions are known for journal bearings only. Little information is available on the reactive forces of annular seals, such as neck ring and interstage seals and balance pistons, and on the impeller interaction forces. The present focus is to establish reliable boundary conditions at annular seals. For this purpose, a full scale test machine was set up and smooth and serrated seal configurations measured. Dimensionless coefficients are presented and compared with a state of the art theory.

High power gas laser amplifier

DOEpatents

Leland, Wallace T.; Stratton, Thomas F.

1981-01-01

A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

Flow-field characteristics of high-temperature annular buoyant jets and their development laws influenced by ventilation system.

PubMed

Wang, Yi; Huang, Yanqiu; Liu, Jiaping; Wang, Hai; Liu, Qiuhan

2013-01-01

The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to -5 Pa.

Flow-Field Characteristics of High-Temperature Annular Buoyant Jets and Their Development Laws Influenced by Ventilation System

PubMed Central

Liu, Jiaping; Wang, Hai; Liu, Qiuhan

2013-01-01

The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to −5 Pa. PMID:24000278

Using the Auditory Hazard Assessment Algorithm for Humans (AHAAH) With Hearing Protection Software, Release MIL-STD-1474E

DTIC Science & Technology

2013-12-01

points in the waveform. This is useful if the digitization rate is unnecessarily high and the waveform content remains unchanged at lower sampling...there is a precursor acoustic event not included in the waveform, like another impulse or high background noise. MIL-STD-1474E defines an exposure as...Breaking strain of annular ligament filaments Ramp 6 unitless ratio Ratio of resistance to stiffness of annular ligament at high loads So 1.00E+09

Rotary distributor type fuel injection pump

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

Klopfer, K.H.; Dordjevic, I.; Higgins, M.C.

1993-07-20

In a fuel injection pump having a pump body and distributor rotor in coaxial alignment, the pump body is described having a pumping chamber provided by an annular arrangement of pumping plunger bores with axes extending generally radially outwardly from the axis of the distributor rotor, a pumping plunger mounted in each plunger bore for reciprocation, annular cam means surrounding the annular arrangement of plunger bores for reciprocating the pumping plungers to provide alternating intake and pumping strokes thereof for respectively supplying intake charges of fuel to the pumping chamber and delivering high pressure charges of fuel from the pumpingmore » chamber for fuel injection, a distributor head with a plurality of distributor outlets, the distributor rotor being rotatably mounted in the distributor head for distributing the high pressure charges of fuel to the distributor outlets; the improvement wherein the pump body and distributor rotor have a central coaxial bore extending there through and providing a valve bore intersecting the annular arrangement of plunger bores, the pump body providing an annular valve seat around the central bore between one end thereof away from the distributor rotor and the intersection of the valve bore and annular arrangement of plunger bores, an elongated valve member mounted in the valve bore having a sealing head at one end thereof engageable with the annular valve seat and extending from the sealing head toward the other end of the central bore, a fuel supply chamber connected to the one end of the central bore for supplying fuel to the pumping chamber, valve actuating means comprising an electromagnet at the other end of the valve member from the sealing head and operable when energized to shift the valve member in one axial direction thereof to one of its the positions, and means for shifting the valve member in the opposite axial direction thereof to its other position when the electromagnet is deenergized.« less

Two-stage fixed-bed gasifier with selectable middle gas off-take point

DOEpatents

Strickland, Larry D.; Bissett, Larry A.

1992-01-01

A two-stage fixed bed coal gasifier wherein an annular region is in registry with a gasification zone underlying a devolatilization zone for extracting a side stream of high temperature substantially tar-free gas from the gasifier. A vertically displaceable skirt means is positioned within the gasifier to define the lower portion of the annular region so that vertical displacement of the skirt means positions the inlet into the annular region in a selected location within or in close proximity to the gasification zone for providing a positive control over the composition of the side stream gas.

A High Frequency Model of Cascade Noise

NASA Technical Reports Server (NTRS)

Envia, Edmane

1998-01-01

Closed form asymptotic expressions for computing high frequency noise generated by an annular cascade in an infinite duct containing a uniform flow are presented. There are two new elements in this work. First, the annular duct mode representation does not rely on the often-used Bessel function expansion resulting in simpler expressions for both the radial eigenvalues and eigenfunctions of the duct. In particular, the new representation provides an explicit approximate formula for the radial eigenvalues obviating the need for solutions of the transcendental annular duct eigenvalue equation. Also, the radial eigenfunctions are represented in terms of exponentials eliminating the numerical problems associated with generating the Bessel functions on a computer. The second new element is the construction of an unsteady response model for an annular cascade. The new construction satisfies the boundary conditions on both the cascade and duct walls simultaneously adding a new level of realism to the noise calculations. Preliminary results which demonstrate the effectiveness of the new elements are presented. A discussion of the utility of the asymptotic formulas for calculating cascade discrete tone as well as broadband noise is also included.

Oxidation-state sensitive imaging of cerium dioxide by atomic-resolution low-angle annular dark field scanning transmission electron microscopy.

PubMed

Johnston-Peck, Aaron C; Winterstein, Jonathan P; Roberts, Alan D; DuChene, Joseph S; Qian, Kun; Sweeny, Brendan C; Wei, Wei David; Sharma, Renu; Stach, Eric A; Herzing, Andrew A

2016-03-01

Low-angle annular dark field (LAADF) scanning transmission electron microscopy (STEM) imaging is presented as a method that is sensitive to the oxidation state of cerium ions in CeO2 nanoparticles. This relationship was validated through electron energy loss spectroscopy (EELS), in situ measurements, as well as multislice image simulations. Static displacements caused by the increased ionic radius of Ce(3+) influence the electron channeling process and increase electron scattering to low angles while reducing scatter to high angles. This process manifests itself by reducing the high-angle annular dark field (HAADF) signal intensity while increasing the LAADF signal intensity in close proximity to Ce(3+) ions. This technique can supplement STEM-EELS and in so doing, relax the experimental challenges associated with acquiring oxidation state information at high spatial resolutions. Published by Elsevier B.V.

Single-stage evaluation of highly-loaded high-Mach-number compressor stages 5. Data and performance of baseline, corner-blow wall suction and combined corner blow wall suction stator

NASA Technical Reports Server (NTRS)

Nikkanen, J. P.; Brooky, J. P.

1972-01-01

A single-stage compressor with a rotor tip speed of 1600 ft/sec and a 0.5 hub tip ratio was used to investigate the effects of several stator endwall treatment methods on stage range and performance. These endwall treatment methods consisted of stator corner-blow, annular wall suction upstream of stator leading edge, and combined corner-blow and annular wall suction. The overall stage performance with corner blow was essentially the same as the baseline performance. The performance for the annular wall suction and the combined corner-blow and wall suction showed a reduction in peak efficiency of 2.5 percentage points compared to the baseline data.

Design and simulation of high resolution optical imaging system based on near-field using solid immersion lens with NA = 2.2

NASA Astrophysics Data System (ADS)

Abbasian, Karim; Sadeghi, Rasool; Sadeghi, Parvin

2014-03-01

In this work, by changing annular aperture zones transmittance, we could get a spot size smaller than any reported one by utilizing annular aperture. Where, by dividing the annular aperture to more than three zones and utilizing of Sony corporation Produced SIL that has NA higher than 2, we could improve imaging resolution for radial polarization (RP); also we could decrease the FWHM from around ? to near ?. Here, the FWHM variation, according to the refractive index changing, has decreased to zero for RP. After that, circular polarization (CP) has been introduced to get a spot size less than ?. This image resolution improving can be applied to enhance optical data storage, microscopes and lithographic and other high accurate optical systems.

Analysis of Foundation of Tall R/C Chimney Incorporating Flexibility of Soil

NASA Astrophysics Data System (ADS)

Jayalekshmi, B. R.; Jisha, S. V.; Shivashankar, R.

2017-09-01

Three dimensional Finite Element (FE) analysis was carried out for 100 and 400 m high R/C chimneys having piled annular raft and annular raft foundations considering the flexibility of soil subjected to across-wind load. Stiffness of supporting soil and foundation were varied to evaluate the significance of Soil-Structure Interaction (SSI). The integrated chimney-foundation-soil system was analysed by finite element software ANSYS based on direct method of SSI assuming linear elastic material behaviour. FE analyses were carried out for two cases of SSI namely, (1) chimney with annular raft foundation and (2) chimney with piled annular raft foundation. The responses in raft such as bending moments and settlements were evaluated for both the cases and compared to those obtained from the conventional method of analysis of annular raft foundation. It is found that the responses in raft vary considerably depending on the stiffness of the underlying soil and the stiffness of foundation. Piled raft foundations are better suited for tall chimneys to be constructed in loose or medium sand.

Split ring floating air riding seal for a turbine

DOEpatents

Mills, Jacob A

2015-11-03

A floating air riding seal for a gas turbine engine with a rotor and a stator, an annular piston chamber with an axial moveable annular piston assembly within the annular piston chamber, an annular cavity formed on the annular piston assembly that faces a seal surface on the rotor, and a central passage connecting the annular cavity to the annular piston chamber to supply compressed air to the seal face, where the annular piston assembly is a split piston assembly to maintain a tight seal as coning of the rotor disk occurs.

High-Throughput Fabrication of Ultradense Annular Nanogap Arrays for Plasmon-Enhanced Spectroscopy.

PubMed

Cai, Hongbing; Meng, Qiushi; Zhao, Hui; Li, Mingling; Dai, Yanmeng; Lin, Yue; Ding, Huaiyi; Pan, Nan; Tian, Yangchao; Luo, Yi; Wang, Xiaoping

2018-06-13

The confinement of light into nanometer-sized metallic nanogaps can lead to an extremely high field enhancement, resulting in dramatically enhanced absorption, emission, and surface-enhanced Raman scattering (SERS) of molecules embedded in nanogaps. However, low-cost, high-throughput, and reliable fabrication of ultra-high-dense nanogap arrays with precise control of the gap size still remains a challenge. Here, by combining colloidal lithography and atomic layer deposition technique, a reproducible method for fabricating ultra-high-dense arrays of hexagonal close-packed annular nanogaps over large areas is demonstrated. The annular nanogap arrays with a minimum diameter smaller than 100 nm and sub-1 nm gap width have been produced, showing excellent SERS performance with a typical enhancement factor up to 3.1 × 10 6 and a detection limit of 10 -11 M. Moreover, it can also work as a high-quality field enhancement substrate for studying two-dimensional materials, such as MoSe 2 . Our method provides an attractive approach to produce controllable nanogaps for enhanced light-matter interaction at the nanoscale.

What causes Mars' annular polar vortices?

NASA Astrophysics Data System (ADS)

Toigo, A. D.; Waugh, D. W.; Guzewich, S. D.

2017-01-01

A distinctive feature of the Martian atmosphere is that the winter polar vortices exhibit annuli of high potential vorticity (PV) with a local minimum near the pole. These annuli are seen in observations, reanalyses, and free-running general circulation model simulations of Mars, but are not generally a feature of Earth's polar vortices, where there is a monotonic increase in magnitude of PV with latitude. The creation and maintenance of the annular polar vortices on Mars are not well understood. Here we use simulations with a Martian general circulation model to the show that annular vortices are related to another distinctive, and possibly unique in the solar system, feature of the Martian atmosphere: the condensation of the predominant atmospheric gas species (CO2) in polar winter regions. The latent heat associated with CO2 condensation leads to destruction of PV in the polar lower atmosphere, inducing the formation of an annular PV structure.

Boron nitride insulating material

DOEpatents

Morgan, Jr., Chester S.; Cavin, O. Burl; McCulloch, Reginald W.; Clark, David L.

1978-01-01

High temperature BN-insulated heaters for use as fuel pin simulators in reactor thermal hydraulic test facility studies comprise a cylindrical housing and a concentric heating element disposed within the housing and spaced apart from the housing to define an annular region therebetween. The annular region contains BN for providing electrical resistance and thermal conductivity between the housing and the heating element. The fabrication method of this invention comprises the steps of cold pressing BN powder at a pressure of 20 to 80,000 psig and a dwell time of at least 0.1-3 seconds to provide hollow cylindrical preforms of suitable dimensions for insertion into the annular region, the BN powder having a tap density of about 0.6-1.1 g/cm.sup.3 and an orientation ratio of at least about 100/3.5. The preforms are inserted into the annular region and crushed in place.

FLUID PRESSURE AND CAM OPERATED VACUUM VALVE

DOEpatents

Batzer, T.H.

1963-11-26

An ultra-high vacuum valve that is bakable, reusable, and capable of being quickly opened and closed is described. A translationally movable valve gate having an annular ridge is adapted to contact an annular soft metal gasket disposed at the valve seat such that the soft metal gasket extends beyond the annular ridge on all sides. The valve gate is closed, by first laterally aligning the valve gate with the valve seat and then bringing the valve gate and valve seat into seating contact by the translational movement of a ramp-like wedging means that engages similar ramp-like stractures at the base of the valve gate to force the valve gate into essentially pressureless contact with the annular soft metal gasket. This gasket is then pressurized from beneath by a fluid thereby effecting a vacuura tight seal between the gasket and the ridge. (AEC)

Floating air riding seal for a turbine

DOEpatents

Ebert, Todd A

2016-08-16

A floating air riding seal for a gas turbine engine with a rotor and a stator, an annular piston chamber with an axial moveable annular piston assembly within the annular piston chamber formed in the stator, an annular cavity formed on the annular piston assembly that faces a seal surface on the rotor, where the axial moveable annular piston includes an inlet scoop on a side opposite to the annular cavity that scoops up the swirling cooling air and directs the cooling air to the annular cavity to form an air cushion with the seal surface of the rotor.

Domain-adaptive finite difference methods for collapsing annular liquid jets

NASA Astrophysics Data System (ADS)

Ramos, J. I.

1993-01-01

A domain-adaptive technique which maps a time-dependent, curvilinear geometry into a unit square is used to determine the steady state mass absorption rate and the collapse of annular liquid jets. A method of lines is used to solve the one-dimensional fluid dynamics equations written in weak conservation-law form, and upwind differences are employed to evaluate the axial convective fluxes. The unknown, time-dependent, axial location of the downstream boundary is determined from the solution of an ordinary differential equation which is nonlinearly coupled to the fluid dynamics and gas concentration equations. The equation for the gas concentration in the annular liquid jet is written in strong conservation-law form and solved by means of a method of lines at high Peclet numbers and a line Gauss-Seidel method at low Peclet numbers. The effects of the number of grid points along and across the annular jet, time step, and discretization of the radial convective fluxes on both the steady state mass absorption rate and the jet's collapse rate have been analyzed on staggered and non-staggered grids. The steady state mass absorption rate and the collapse of annular liquid jets are determined as a function of the Froude, Peclet and Weber numbers, annular jet's thickness-to-radius ratio at the nozzle exit, initial pressure difference across the annular jet, nozzle exit angle, temperature of the gas enclosed by the annular jet, pressure of the gas surrounding the jet, solubilities at the inner and outer interfaces of the annular jet, and gas concentration at the nozzle exit. It is shown that the steady state mass absorption rate is proportional to the inverse square root of the Peclet number except for low values of this parameter, and that the possible mathematical incompatibilities in the concentration field at the nozzle exit exert a great influence on the steady state mass absorption rate and on the jet collapse. It is also shown that the steady state mass absorption rate increases as the Weber number, nozzle exit angle, gas concentration at the nozzle exit, and temperature of the gases enclosed by the annular liquid jet are increased, but it decreases as the Froude and Peclet numbers, and annular liquid jet's thickness-to-radius ratio at the nozzle exit are increased. It is also shown that the annular liquid jet's collapse rate increases as the Weber number, nozzle exit angle, temperature of the gases enclosed by the annular liquid jet, and pressure of the gases which surround the jet are increased, but decreases as the Froude and Peclet numbers, and annular liquid jet's thickness-toradius ratio at the nozzle exit are increased. It is also shown that both the ratio of the initial pressure of the gas enclosed by the jet to the pressure of the gas surrounding the jet and the ratio of solubilities at the annular liquid jet's inner and outer interfaces play an important role on both the steady state mass absorption rate and the jet collapse. If the product of these ratios is greater or less than one, both the pressure and the mass of the gas enclosed by the annular liquid jet decrease or increase, respectively, with time. It is also shown that the numerical results obtained with the conservative, domain-adaptive method of lines technique presented in this paper are in excellent agreement with those of a domain-adaptive, iterative, non-conservative, block-bidiagonal, finite difference method which uncouples the solution of the fluid dynamics equations from that of the convergence length.

Device and method for relativistic electron beam heating of a high-density plasma to drive fast liners

DOEpatents

Thode, Lester E.

1981-01-01

A device and method for relativistic electron beam heating of a high-density plasma in a small localized region. A relativistic electron beam generator or accelerator produces a high-voltage electron beam which propagates along a vacuum drift tube and is modulated to initiate electron bunching within the beam. The beam is then directed through a low-density gas chamber which provides isolation between the vacuum modulator and the relativistic electron beam target. The relativistic beam is then applied to a high-density target plasma which typically comprises DT, DD, hydrogen boron or similar thermonuclear gas at a density of 10.sup.17 to 10.sup.20 electrons per cubic centimeter. The target gas is ionized prior to application of the electron beam by means of a laser or other preionization source to form a plasma. Utilizing a relativistic electron beam with an individual particle energy exceeding 3 MeV, classical scattering by relativistic electrons passing through isolation foils is negligible. As a result, relativistic streaming instabilities are initiated within the high-density target plasma causing the relativistic electron beam to efficiently deposit its energy and momentum into a small localized region of the high-density plasma target. Fast liners disposed in the high-density target plasma are explosively or ablatively driven to implosion by a heated annular plasma surrounding the fast liner which is generated by an annular relativistic electron beam. An azimuthal magnetic field produced by axial current flow in the annular plasma, causes the energy in the heated annular plasma to converge on the fast liner.

Statistical assessment of normal mitral annular geometry using automated three-dimensional echocardiographic analysis.

PubMed

Pouch, Alison M; Vergnat, Mathieu; McGarvey, Jeremy R; Ferrari, Giovanni; Jackson, Benjamin M; Sehgal, Chandra M; Yushkevich, Paul A; Gorman, Robert C; Gorman, Joseph H

2014-01-01

The basis of mitral annuloplasty ring design has progressed from qualitative surgical intuition to experimental and theoretical analysis of annular geometry with quantitative imaging techniques. In this work, we present an automated three-dimensional (3D) echocardiographic image analysis method that can be used to statistically assess variability in normal mitral annular geometry to support advancement in annuloplasty ring design. Three-dimensional patient-specific models of the mitral annulus were automatically generated from 3D echocardiographic images acquired from subjects with normal mitral valve structure and function. Geometric annular measurements including annular circumference, annular height, septolateral diameter, intercommissural width, and the annular height to intercommissural width ratio were automatically calculated. A mean 3D annular contour was computed, and principal component analysis was used to evaluate variability in normal annular shape. The following mean ± standard deviations were obtained from 3D echocardiographic image analysis: annular circumference, 107.0 ± 14.6 mm; annular height, 7.6 ± 2.8 mm; septolateral diameter, 28.5 ± 3.7 mm; intercommissural width, 33.0 ± 5.3 mm; and annular height to intercommissural width ratio, 22.7% ± 6.9%. Principal component analysis indicated that shape variability was primarily related to overall annular size, with more subtle variation in the skewness and height of the anterior annular peak, independent of annular diameter. Patient-specific 3D echocardiographic-based modeling of the human mitral valve enables statistical analysis of physiologically normal mitral annular geometry. The tool can potentially lead to the development of a new generation of annuloplasty rings that restore the diseased mitral valve annulus back to a truly normal geometry. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

An integral equation formulation for predicting radiation patterns of a space shuttle annular slot antenna

NASA Technical Reports Server (NTRS)

Jones, J. E.; Richmond, J. H.

1974-01-01

An integral equation formulation is applied to predict pitch- and roll-plane radiation patterns of a thin VHF/UHF (very high frequency/ultra high frequency) annular slot communications antenna operating at several locations in the nose region of the space shuttle orbiter. Digital computer programs used to compute radiation patterns are given and the use of the programs is illustrated. Experimental verification of computed patterns is given from measurements made on 1/35-scale models of the orbiter.

Fast-Acting Valve

NASA Technical Reports Server (NTRS)

Wojciechowski, Bogdan V. (Inventor); Pegg, Robert J. (Inventor)

2003-01-01

A fast-acting valve includes an annular valve seat that defines an annular valve orifice between the edges of the annular valve seat, an annular valve plug sized to cover the valve orifice when the valve is closed, and a valve-plug holder for moving the annular valve plug on and off the annular valve seat. The use of an annular orifice reduces the characteristic distance between the edges of the valve seat. Rather than this distance being equal to the diameter of the orifice, as it is for a conventional circular orifice, the characteristic distance equals the distance between the inner and outer radii (for a circular annulus). The reduced characteristic distance greatly reduces the gap required between the annular valve plug and the annular valve seat for the valve to be fully open, thereby greatly reducing the required stroke and corresponding speed and acceleration of the annular valve plug. The use of a valve-plug holder that is under independent control to move the annular valve plug between its open and closed positions is important for achieving controllable fast operation of the valve.

Design and testing of an annular array for very-high-frequency imaging

NASA Astrophysics Data System (ADS)

Ketterling, Jeffrey A.; Ramachandran, Sarayu; Lizzi, Frederic L.; Aristizábal, Orlando; Turnbull, Daniel H.

2004-05-01

Very-high-frequency ultrasound (VHFU) transducer technology is currently experiencing a great deal of interest. Traditionally, researchers have used single-element transducers which achieve exceptional lateral image resolution although at a very limited depth of field. A 5-ring focused annular array, a transducer geometry that permits an increased depth of field via electronic focusing, has been constructed. The transducer is fabricated with a PVDF membrane and a copper-clad Kapton film with an annular array pattern. The PVDF is bonded to the Kapton film and pressed into a spherically curved shape. The back side of the transducer is then filled with epoxy. One side of the PVDF is metallized with gold, forming the ground plane of the transducer. The array elements are accessed electrically via copper traces formed on the Kapton film. The annular array consists of 5 equal-area rings with an outer diameter of 1 cm and a radius of curvature of 9 mm. A wire reflector target was used to test the imaging capability of the transducer by acquiring B-scan data for each transmit/receive pair. A synthetic aperture approach was then used to reconstruct the image and demonstrate the enhanced depth of field capabilities of the transducer.

Device and method for imploding a microsphere with a fast liner

DOEpatents

Thode, Lester E.

1981-01-01

A device and method for relativistic electron beam heating of a high-density plasma in a small localized region. A relativistic electron beam generator or accelerator produces a high-voltage electron beam which propagates along a vacuum drift tube and is modulated to initiate electron bunching within the beam. The beam is then directed through a low-density gas chamber which provides isolation between the vacuum modulator and the relativistic electron beam target. The relativistic beam is then applied to a high-density target plasma which typically comprises DT, DD, hydrogen boron or similar thermonuclear gas at a density of 10.sup.17 to 10.sup.20 electrons per cubic centimeter. The target gas is ionized prior to application of the electron beam by means of a laser or other preionization source to form a plasma. Utilizing a relativistic electron beam with an individual particle energy exceeding 3 MeV, classical scattering by relativistic electrons passing through isolation foils is negligible. As a result, relativistic streaming instabilities are initiated within the high-density target plasma causing the relativistic electron beam to efficiently deposit its energy and momentum into a small localized region of the high-density plasma target. Fast liners disposed in the high-density target plasma are explosively or ablatively driven to implosion by a heated annular plasma surrounding the fast liner generated by an annular relativistic electron beam. An azimuthal magnetic field produced by axial current flow in the annular plasma, causes the energy in the heated annular plasma to converge on the fast liner to drive the fast liner to implode a microsphere.

The Penetration Behavior of an Annular Gas-Solid Jet Impinging on a Liquid Bath: Comparison with a Conventional Circular Jet

NASA Astrophysics Data System (ADS)

Park, Sung Sil; Dyussekenov, Nurzhan; Sohn, H. Y.

2010-02-01

The top-blow injection technique of a gas-solid mixture through a circular lance is used in the Mitsubishi Continuous Smelting Process. One of the inherent problems associated with this injection is the severe erosion of the hearth refractory below the lances. A new configuration of the lance to form an annular gas-solid jet rather than a circular jet was designed in the laboratory scale. With this new configuration, solid particles leave the lance at a much lower velocity than the gas, and the penetration behavior of the jet is significantly different than with the circular lance in which the solid particles leave the lance at the same high velocity as the gas. The results of cold model tests using an air-sand jet issuing from a circular lance and an annular lance into a water bath showed that the penetration of the annular jet is much less sensitive to the variations in particle feed rate as well as gas velocity than that of the circular jet. Correlation equations for the penetration depth for both circular and annular jets show agreement among the experimentally obtained values.

Novel Accident-Tolerant Fuel Meat and Cladding

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

Robert D. Mariani; Pavel G Medvedev; Douglas L Porter

A novel accident-tolerant fuel meat and cladding are here proposed. The fuel meat design incorporates annular fuel with inserts and discs that are fabricated from a material having high thermal conductivity, for example niobium. The inserts are rods or tubes. Discs separate the fuel pellets. Using the BISON fuel performance code it was found that the peak fuel temperature can be lowered by more than 600 degrees C for one set of conditions with niobium metal as the thermal conductor. In addition to improved safety margin, several advantages are expected from the lower temperature such as decreased fission gas releasemore » and fuel cracking. Advantages and disadvantages are discussed. An enrichment of only 7.5% fully compensates the lost reactivity of the displaced UO2. Slightly higher enrichments, such as 9%, allow uprates and increased burnups to offset the initial costs for retooling. The design has applications for fast reactors and transuranic burning, which may accelerate its development. A zirconium silicide coating is also described for accident tolerant applications. A self-limiting degradation behavior for this coating is expected to produce a glassy, self-healing layer that becomes more protective at elevated temperature, with some similarities to MoSi2 and other silicides. Both the fuel and coating may benefit from the existing technology infrastructure and the associated wide expertise for a more rapid development in comparison to other, more novel fuels and cladding.« less

Annular Focused Electron/Ion Beams for Combining High Spatial Resolution with High Probe Current.

PubMed

Khursheed, Anjam; Ang, Wei Kean

2016-10-01

This paper presents a proposal for reducing the final probe size of focused electron/ion beam columns that are operated in a high primary beam current mode where relatively large final apertures are used, typically required in applications such as electron beam lithography, focused ion beams, and electron beam spectroscopy. An annular aperture together with a lens corrector unit is used to replace the conventional final hole-aperture, creating an annular ring-shaped primary beam. The corrector unit is designed to eliminate the first- and second-order geometric aberrations of the objective lens, and for the same probe current, the final geometric aberration limited spot size is predicted to be around a factor of 50 times smaller than that of the corresponding conventional hole-aperture beam. Direct ray tracing simulation is used to illustrate how a three-stage core lens corrector can be used to eliminate the first- and second-order geometric aberrations of an electric Einzel objective lens.

Cleft closure and undersizing annuloplasty improve mitral repair in atrioventricular canal defects

PubMed Central

Padala, Muralidhar; Vasilyev, Nikolay V.; Owen, James W.; Jimenez, Jorge H.; Dasi, Lakshmi P.; del Nido, Pedro J.; Yoganathan, Ajit P.

2009-01-01

Objective Reoperation rates to correct left atrioventricular valve regurgitation after primary repair of atrioventricular canal defects remain relatively high. The causes of valvular regurgitation are likely multifactorial, and simple cleft closure is often insufficient to prevent recurrence. Methods To elucidate the mechanisms leading to regurgitation, we conducted hemodynamic studies using isolated native mitral valves. Anatomy of these valves was altered to mimic atrioventricular canal type valves and studied under pediatric hemodynamic conditions. The impact of subvalvular geometry, cleft closure, annular dilatation, and annular undersizing on regurgitation were investigated. Results Papillary muscle position did not have a significant effect on regurgitation. Cleft closure had a significant impact on valvular competence, with reduction in regurgitation volume with increased cleft closure. Regurgitation volume decreased from 12.5 ± 2.4 mL/beat for an open cleft to 4.9 ± 1.9 mL/beat for a partially closed cleft and to 1.4 ± 1.6 mL/beat when the cleft was completely closed. Annular dilatation had a significant impact on regurgitation even after cleft closure. A 40% increase in annular size increased regurgitation by 59% for a partially closed cleft and by 84% for a fully closed cleft. Reducing the annular size by 20% from the physiologic level decreased the regurgitation volume by 12% for a fully open cleft and by 58% for the partially closed cleft case. Conclusions Annular dilatation after primary repair has a potentially significant role in the recurrence of atrioventricular valve regurgitation. Reducing the annular size and restricting dilatation as an adjunct to cleft closure is a promising surgical approach in such valve anatomies. PMID:19026810

Triple acting radial seal

DOEpatents

Ebert, Todd A [West Palm Beach, FL; Carella, John A [Jupiter, FL

2012-03-13

A triple acting radial seal used as an interstage seal assembly in a gas turbine engine, where the seal assembly includes an interstage seal support extending from a stationary inner shroud of a vane ring, the interstage seal support includes a larger annular radial inward facing groove in which an outer annular floating seal assembly is secured for radial displacement, and the outer annular floating seal assembly includes a smaller annular radial inward facing groove in which an inner annular floating seal assembly is secured also for radial displacement. A compliant seal is secured to the inner annular floating seal assembly. The outer annular floating seal assembly encapsulates the inner annular floating seal assembly which is made from a very low alpha material in order to reduce thermal stress.

Improved Electrical Contact For Dowhhole Drilling Networks

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron

2005-08-16

An electrical contact system for transmitting information across tool joints while minimizing signal reflections that occur at the tool joints includes a first electrical contact comprising an annular resilient material. An annular conductor is embedded within the annular resilient material and has a surface exposed from the annular resilient material. A second electrical contact is provided that is substantially equal to the first electrical contact. Likewise, the second electrical contact has an annular resilient material and an annular conductor. The two electrical contacts configured to contact one another such that the annular conductors of each come into physical contact. The annular resilient materials of each electrical contact each have dielectric characteristics and dimensions that are adjusted to provide desired impedance to the electrical contacts.

Ultrathin zoom lens system based on liquid lenses

NASA Astrophysics Data System (ADS)

Li, Lei; Liu, Chao; Wang, Qiong-Hua

2015-07-01

In this paper, we propose an ultrathin zoom lens system based on liquid lenses. The proposed system consists of an annular folded lens and three electrowetting liquid lenses. The annular folded lens has several concentric surfaces. The annular folded lens is used to get the main power and correct aberrations. The three liquid lenses are used to change the focal length and correct aberration. An analysis of the proposed system is presented along with the design, fabrication, and testing of a prototype. All the elements in the proposed system are very thin, so the system is an ultrathin zoom lens system, which has potential application as lightweight, thin, high-quality imagers for aerospace, consumer, and military applications.

Annular arc accelerator shock tube

NASA Technical Reports Server (NTRS)

Leibowitz, L. P. (Inventor)

1976-01-01

An annular arc accelerator shock tube employs a cold gas driver to flow a stream of gas from an expansion section through a high voltage electrode section to a test section, thus driving a shock wave in front of it. A glow discharge detects the shock wave and actuates a trigger generator which in turn fires spark-gap switches to discharge a bank of capacitors across a centered cathode and an annular anode in tandem electrode sections. The initial shock wave passes through the anode section from the cathode section thereby depositing energy into the flow gas without the necessity of any diaphragm opening in the gas flow from the expansion section through the electrode sections.

Effect of multiply charged ions on the performance and beam characteristics in annular and cylindrical type Hall thruster plasmas

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

Kim, Holak; Lim, Youbong; Choe, Wonho, E-mail: wchoe@kaist.ac.kr

2014-10-06

Plasma plume and thruster performance characteristics associated with multiply charged ions in a cylindrical type Hall thruster (CHT) and an annular type Hall thruster are compared under identical conditions such as channel diameter, channel depth, propellant mass flow rate. A high propellant utilization in a CHT is caused by a high ionization rate, which brings about large multiply charged ions. Ion currents and utilizations are much different due to the presence of multiply charged ions. A high multiply charged ion fraction and a high ionization rate in the CHT result in a higher specific impulse, thrust, and discharge current.

ISSLS prize winner: microstructure and mechanical disruption of the lumbar disc annulus: part II: how the annulus fails under hydrostatic pressure.

PubMed

Veres, Samuel P; Robertson, Peter A; Broom, Neil D

2008-12-01

Mechanically induced annular disruption of lumbar intervertebral discs followed by microstructural investigation. To investigate the role that elevated nuclear pressures play in disrupting the lumbar intervertebral disc's annulus fibrosus. Compound mechanical loadings have been used to recreate clinically relevant annular disruptions in vitro. However, the role that individual loading parameters play in disrupting the lumbar disc's annulus remains unclear. The nuclei of ovine lumbar intervertebral discs were gradually pressurized by injecting a viscous radio-opaque gel via their inferior vertebrae. Pressurization was conducted until catastrophic failure of the disc occurred. Investigation of the resulting annular disruption was carried out using microcomputed tomography and differential interference contrast microscopy. Gel extrusion from the posterior annulus was the most common mode of disc failure. Unlike other aspects of the annular wall, the posterior region was unable to distribute hydrostatic pressures circumferentially. In each extrusion case, severe disruption of the posterior annulus occurred. Although intralamellar disruption occurred in the mid annulus, interlamellar disruption occurred in the outer posterior annulus. Radial ruptures between lamellae always occurred in the mid-axial plane. With respect to the annular wall, the posterior region is most susceptible to failure in the presence of high nuclear pressure, even when loaded in the neutral position. Weak interlamellar cohesion of the outer posterior lamellae may explain why the majority of herniations remain contained as protrusions within the outer annular wall.

Measurements in the annular shear layer of high subsonic and under-expanded round jets

NASA Astrophysics Data System (ADS)

Feng, Tong; McGuirk, James J.

2016-01-01

An experimental study has been undertaken to document compressibility effects in the annular shear layers of axisymmetric jets. Comparison is made of the measured flow development with the well-documented influence of compressibility in planar mixing layers. High Reynolds number (~106) and high Mach number jets issuing from a convergent nozzle at nozzle pressure ratios (NPRs) from 1.28 to 3.0 were measured using laser Doppler anemometry instrumentation. Detailed radial profile data are reported, particularly within the potential core region, for mean velocity, turbulence rms, and turbulence shear stress. For supercritical NPRs the presence of the pressure waves in the inviscid shock cell region as the jet expanded back to ambient pressure was found to exert a noticeable effect on shear layer location, causing this to shift radially outwards at high supercritical NPR conditions. After a boundary layer to free shear layer transition zone, the turbulence development displayed a short region of similarity before adjustment to near-field merged jet behaviour. Peak turbulence rms reduction due to compressibility was similar to that observed in planar layers with radial rms suppression much stronger than axial. Comparison of the compressibility-modified annular shear layer growth rate with planar shear layer data on the basis of the convective Mach number ( M C) showed notable differences; in the annular shear layer, compressibility effects began at lower M C and displayed a stronger reduction in growth. For high Mach number aerospace propulsion applications involving round jets, the current measurements represent a new data set for the calibration/validation of compressibility-affected turbulence models.

Improving the trapping capability using radially polarized narrow-width annular beam

NASA Astrophysics Data System (ADS)

Xu, Hua-Feng; Zhang, Wei-Jun; Qu, Jun; Huang, Wei

2016-03-01

A novel optical-trap method for improving the trapping capability using a radially polarized narrow-width annular beam (NWAB) has been proposed. In this paper, we theoretically study the tight focusing properties of a radially polarized NWAB, formed by subtly blocking the central portion of a radially polarized Bessel-Gaussian beam (the original doughnut beam), through a high-numerical aperture objective. It is shown that a sub-wavelength focal spot (?) with a quite long depth of focus (about ?) can be formed in the vicinity of the focus. Furthermore, the optical trapping forces acting on a metallic Rayleigh particle are calculated for the case where a radially polarized annular beam is applied. Numerical results show that the radially polarized NWAB can largely enhance the transverse trap stiffness and broaden the longitudinal trap range compared with the usage of the original doughnut beam. The influence of the annular factor δ on the focusing properties and the trap stiffness is investigated in detail.

Effect of a semi-annular thermal acoustic shield on jet exhaust noise

NASA Technical Reports Server (NTRS)

Goodykoontz, J.

1980-01-01

The effect of a semi-annular acoustic shield on jet exhaust noise is investigated with the rationale that such a configuration would reduce or eliminate the multiple reflection mechanism. A limited range of flow conditions for one nozzle/shield configuration were studied at model scale. Noise measurements for a 10 cm conical nozzle with a semi-annular acoustical shield are presented in terms of lossless free field data at various angular locations with respect to the nozzle. Measurements were made on both the shielded and unshielded sides of the nozzle. Model scale overall sound pressure level directivity patterns and comparisons of model scale spectral data are provided. The results show that a semi-annular thermal acoustic shield consisting of a low velocity, high temperature gas stream partially surrounding a central jet exhibits lower noise levels than when the central jet is operated alone. The results are presented parametrically, showing the effects of various shield and central system velocities and temperatures.

The convertible flywheel

NASA Astrophysics Data System (ADS)

Ginsburg, B. R.

The design and testing of a new twin-disk composite flywheel is described. It is the first flywheel to store 2 kW-hr of energy and the first to successfully combine the advantages of composite materials with metal hubs, thus providing a system-ready flywheel with high energy storage and high torque capabilities. The use of flywheels in space for energy storage in satellites and space stations is examined. The convertibility of the present flywheel to provide the next generation Annular Momentum Control Device or Annular Suspension and Pointing System is discussed.

Wire-number effects on high-power annular z-pinches and some characteristics at high wire number

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

SANFORD,THOMAS W. L.

2000-05-23

Characteristics of annular wire-array z-pinches as a function of wire number and at high wire number are reviewed. The data, taken primarily using aluminum wires on Saturn are comprehensive. The experiments have provided important insights into the features of wire-array dynamics critical for high x-ray power generation, and have initiated a renaissance in z-pinches when high numbers of wires are used. In this regime, for example, radiation environments characteristic of those encountered during the early pulses required for indirect-drive ICF ignition on the NIF have been produced in hohlraums driven by x-rays from a z-pinch, and are commented on here.

Air riding seal for a turbine

DOEpatents

Mills, Jacob A; Brown, Wesley D; Sexton, Thomas D; Jones, Russell B

2016-07-19

An air riding seal between a rotor and a stator in a turbine of a gas turbine engine, where an annular piston is movable in an axial direction within a housing that extends from the stator, and a bellows is secured to the annular piston to form a flexible air passageway from a compressed air inlet through the annular piston and into a cushion cavity that forms an air riding seal between the annular piston and the rotor sealing surface. In another embodiment, a flexible seal secured to and extending from the annular piston forms a sealing surface between the annular piston chamber and the annular piston to provide a seal and allow for axial movement.

The Penetration Behavior of an Annular Gas-Solid Jet Impinging on a Liquid Bath: The Effects of the Density and Size of Solid Particles

NASA Astrophysics Data System (ADS)

Chang, J. S.; Sohn, H. Y.

2012-08-01

Top-blow injection of a gas-solid jet through a circular lance is used in the Mitsubishi Continuous Smelting Process. One problem associated with this injection is the severe erosion of the hearth refractory below the lances. A new configuration of the lance to form an annular gas-solid jet rather than the circular jet was designed in this laboratory. With this new configuration, the solid particles fed through the center tube leave the lance at a much lower velocity than the gas, and the penetration behavior of the jet is significantly different from that with a circular lance where the solid particles leave the lance at the same high velocity as the gas. In previous cold-model investigations in this laboratory, the effects of the gas velocity, particle feed rate, lance height of the annular lance, and the cross-sectional area of the gas jet were studied and compared with the circular lance. This study examined the effect of the density and size of the solid particles on the penetration behavior of the annular gas-solid jet, which yielded some unexpected results. The variation in the penetration depth with the density of the solid particles at the same mass feed rate was opposite for the circular lance and the annular lance. In the case of the circular lance, the penetration depth became shallower as the density of the solid particles increased; on the contrary, for the annular lance, the penetration depth became deeper with the increasing density of particles. However, at the same volumetric feed rate of the particles, the density effect was small for the circular lance, but for the annular lance, the jets with higher density particles penetrated more deeply. The variation in the penetration depth with the particle diameter was also different for the circular and the annular lances. With the circular lance, the penetration depth became deeper as the particle size decreased for all the feed rates, but with the annular lance, the effect of the particle size was small. The overall results including the previous work indicated that the penetration behavior of an annular jet is much less sensitive to the variations in operating variables than that of a circular jet. Correlation equations for the penetration depth that show good agreements with the measured values have been developed.

Characteristics of the annular beam using a single axicon and a pair of lens

NASA Astrophysics Data System (ADS)

Ji, Ke; Lei, Ming; Yao, Baoli; Yan, Shaohui; Yang, Yanlong; Li, Ze; Dan, Dan; Menke, Neimule

2012-10-01

In optical trapping, annular beam as a kind of hollow beam is used to increase the axial trapping efficiency as well as the trapping stability. In this paper, a method for producing an annular beam by a system consisting of a single axicon and a pair of lens is proposed. The generated beam was also used as the optical tweezers. We use the geometrical optics to describe the propagation of light in the system. The calculated intensity distribution in three-dimensional space after the system shows a good agreement with the experimental results. The advantages of this method are simplicity of operation, good stability, and high transmittance, having possible applications in fields like optical microscopic, optical manipulation and electronic acceleration, etc.

High-Frequency Ultrasonic Imaging of the Anterior Segment Using an Annular Array Transducer

PubMed Central

Silverman, Ronald H.; Ketterling, Jeffrey A.; Coleman, D. Jackson

2006-01-01

Objective Very-high-frequency (>35 MHz) ultrasound (VHFU) allows imaging of anterior segment structures of the eye with a resolution of less than 40-μm. The low focal ratio of VHFU transducers, however, results in a depth-of-field (DOF) of less than 1-mm. Our aim was to develop a high-frequency annular array transducer for ocular imaging with improved DOF, sensitivity and resolution compared to conventional transducers. Design Experimental Study Participants Cadaver eyes, ex vivo cow eyes, in vivo rabbit eyes. Methods A spherically curved annular array ultrasound transducer was fabricated. The array consisted of five concentric rings of equal area, had an overall aperture of 6 mm and a geometric focus of 12 mm. The nominal center frequency of all array elements was 40 MHz. An experimental system was designed in which a single array element was pulsed and echo data recorded from all elements. By sequentially pulsing each element, echo data were acquired for all 25 transmit/receive annuli combinations. The echo data were then synthetically focused and composite images produced. Transducer operation was tested by scanning a test object consisting of a series of 25-μm diameter wires spaced at increasing range from the transducer. Imaging capabilities of the annular array were demonstrated in ex vivo bovine, in vivo rabbit and human cadaver eyes. Main Outcome Measures Depth of field, resolution and sensitivity. Results The wire scans verified the operation of the array and demonstrated a 6.0 mm DOF compared to the 1.0 mm DOF of a conventional single-element transducer of comparable frequency, aperture and focal length. B-mode images of ex vivo bovine, in vivo rabbit and cadaver eyes showed that while the single-element transducer had high sensitivity and resolution within 1–2 mm of its focus, the array with synthetic focusing maintained this quality over a 6 mm DOF. Conclusion An annular array for high-resolution ocular imaging has been demonstrated. This technology offers improved depth-of-field, sensitivity and lateral resolution compared to single-element fixed focus transducers currently used for VHFU imaging of the eye. PMID:17141314

High-frequency ultrasonic imaging of the anterior segment using an annular array transducer.

PubMed

Silverman, Ronald H; Ketterling, Jeffrey A; Coleman, D Jackson

2007-04-01

Very high-frequency ultrasound (VHFU; >35 megahertz [MHz]) allows imaging of anterior segment structures of the eye with a resolution of less than 40 microm. The low focal ratio of VHFU transducers, however, results in a depth of field (DOF) of less than 1 mm. The aim was to develop a high-frequency annular array transducer for ocular imaging with improved DOF, sensitivity, and resolution compared with conventional transducers. Experimental study. Cadaver eyes, ex vivo cow eyes, in vivo rabbit eyes. A spherically curved annular array ultrasound transducer was fabricated. The array consisted of 5 concentric rings of equal area, had an overall aperture of 6 mm, and a geometric focus of 12 mm. The nominal center frequency of all array elements was 40 MHz. An experimental system was designed in which a single array element was pulsed and echo data were recorded from all elements. By sequentially pulsing each element, echo data were acquired for all 25 transmit-and-receive annuli combinations. The echo data then were focused synthetically and composite images were produced. Transducer operation was tested by scanning a test object consisting of a series of 25-microm diameter wires spaced at increasing range from the transducer. Imaging capabilities of the annular array were demonstrated in ex vivo bovine, in vivo rabbit, and human cadaver eyes. Depth of field, resolution, and sensitivity. The wire scans verified the operation of the array and demonstrated a 6.0-mm DOF, compared with the 1.0-mm DOF of a conventional single-element transducer of comparable frequency, aperture, and focal length. B-mode images of ex vivo bovine, in vivo rabbit, and cadaver eyes showed that although the single-element transducer had high sensitivity and resolution within 1 to 2 mm of its focus, the array with synthetic focusing maintained this quality over a 6-mm DOF. An annular array for high-resolution ocular imaging has been demonstrated. This technology offers improved DOF, sensitivity, and lateral resolution compared with single-element fixed focus transducers currently used for VHFU imaging of the eye.

Imaging of high-angle annular dark-field scanning transmission electron microscopy and observations of GaN-based violet laser diodes.

PubMed

Shiojiri, M; Saijo, H

2006-09-01

The first part of this paper is devoted to physics, to explain high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging and to interpret why HAADF-STEM imaging is incoherent, instructing a strict definition of interference and coherence of electron waves. Next, we present our recent investigations of InGaN/GaN multiple quantum wells and AlGaN/GaN strained-layer superlattice claddings in GaN-based violet laser diodes, which have been performed by HAADF-STEM and high-resolution field-emission gun scanning electron microscopy.

Critical experiments at Sandia National Laboratories : technical meeting on low-power critical facilities and small reactors.

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

Harms, Gary A.; Ford, John T.; Barber, Allison Delo

2010-11-01

Sandia National Laboratories (SNL) has conducted radiation effects testing for the Department of Energy (DOE) and other contractors supporting the DOE since the 1960's. Over this period, the research reactor facilities at Sandia have had a primary mission to provide appropriate nuclear radiation environments for radiation testing and qualification of electronic components and other devices. The current generation of reactors includes the Annular Core Research Reactor (ACRR), a water-moderated pool-type reactor, fueled by elements constructed from UO2-BeO ceramic fuel pellets, and the Sandia Pulse Reactor III (SPR-III), a bare metal fast burst reactor utilizing a uranium-molybdenum alloy fuel. The SPR-IIImore » is currently defueled. The SPR Facility (SPRF) has hosted a series of critical experiments. A purpose-built critical experiment was first operated at the SPRF in the late 1980's. This experiment, called the Space Nuclear Thermal Propulsion Critical Experiment (CX), was designed to explore the reactor physics of a nuclear thermal rocket motor. This experiment was fueled with highly-enriched uranium carbide fuel in annular water-moderated fuel elements. The experiment program was completed and the fuel for the experiment was moved off-site. A second critical experiment, the Burnup Credit Critical Experiment (BUCCX) was operated at Sandia in 2002. The critical assembly for this experiment was based on the assembly used in the CX modified to accommodate low-enriched pin-type fuel in water moderator. This experiment was designed as a platform in which the reactivity effects of specific fission product poisons could be measured. Experiments were carried out on rhodium, an important fission product poison. The fuel and assembly hardware for the BUCCX remains at Sandia and is available for future experimentation. The critical experiment currently in operation at the SPRF is the Seven Percent Critical Experiment (7uPCX). This experiment is designed to provide benchmark reactor physics data to support validation of the reactor physics codes used to design commercial reactor fuel elements in an enrichment range above the current 5% enrichment cap. A first set of critical experiments in the 7uPCX has been completed. More experiments are planned in the 7uPCX series. The critical experiments at Sandia National Laboratories are currently funded by the US Department of Energy Nuclear Criticality Safety Program (NCSP). The NCSP has committed to maintain the critical experiment capability at Sandia and to support the development of a critical experiments training course at the facility. The training course is intended to provide hands-on experiment experience for the training of new and re-training of practicing Nuclear Criticality Safety Engineers. The current plans are for the development of the course to continue through the first part of fiscal year 2011 with the development culminating is the delivery of a prototype of the course in the latter part of the fiscal year. The course will be available in fiscal year 2012.« less

Annular resonators for high-power chemical lasers

NASA Astrophysics Data System (ADS)

Wade, Richard C.

1993-08-01

Resonators capable of extracting highly coherent energy from DF and HF chemical laser annular gain media have been under investigation for weapon application since 1974. This survey article traces the background of interest in these devices, describes the various concepts that have been experimentally and analytically investigated, and discusses the issues associated with their operation. From the discussion of issues, preferred concepts are selected. Applicability of these concepts to high-power operation is addressed through discussions of past and ongoing high-power demonstration programs and the issues facing their application to weapon sized devices capable of strategic and tactical missions such as ballistic missile defense (BMD), theater missile defense (TMD), and anti satellite (ASAT).

A coaxial-output capacitor-loaded annular pulse forming line.

PubMed

Li, Rui; Li, Yongdong; Su, Jiancang; Yu, Binxiong; Xu, Xiudong; Zhao, Liang; Cheng, Jie; Zeng, Bo

2018-04-01

A coaxial-output capacitor-loaded annular pulse forming line (PFL) is developed in order to reduce the flat top fluctuation amplitude of the forming quasi-square pulse and improve the quality of the pulse waveform produced by a Tesla-pulse forming network (PFN) type pulse generator. A single module composed of three involute dual-plate PFNs is designed, with a characteristic impedance of 2.44 Ω, an electrical length of 15 ns, and a sustaining voltage of 60 kV. The three involute dual-plate PFNs connected in parallel have the same impedance and electrical length. Due to the existed small inductance and capacitance per unit length in each involute dual-plate PFN, the upper cut-off frequency of the PFN is increased. As a result, the entire annular PFL has better high-frequency response capability. Meanwhile, the three dual-plate PFNs discharge in parallel, which is much closer to the coaxial output. The series connecting inductance between adjacent two modules is significantly reduced when the annular PFL modules are connected in series. The pulse waveform distortion is reduced when the pulse transfers along the modules. Finally, the shielding electrode structure is applied on both sides of the module. The electromagnetic field is restricted in the module when a single module discharges, and the electromagnetic coupling between the multi-stage annular PFLs is eliminated. Based on the principle of impedance matching between the multi-stage annular PFL and the coaxial PFL, the structural optimization design of a mixed PFL in a Tesla type pulse generator is completed with the transient field-circuit co-simulation method. The multi-stage annular PFL consists of 18 stage annular PFL modules in series, with the characteristic impedance of 44 Ω, the electrical length of 15 ns, and the sustaining voltage of 1 MV. The mixed PFL can generate quasi-square electrical pulses with a pulse width of 43 ns, and the fluctuation ratio of the pulse flat top is less than 8% when the pulse rise time is about 5 ns.

A coaxial-output capacitor-loaded annular pulse forming line

NASA Astrophysics Data System (ADS)

Li, Rui; Li, Yongdong; Su, Jiancang; Yu, Binxiong; Xu, Xiudong; Zhao, Liang; Cheng, Jie; Zeng, Bo

2018-04-01

A coaxial-output capacitor-loaded annular pulse forming line (PFL) is developed in order to reduce the flat top fluctuation amplitude of the forming quasi-square pulse and improve the quality of the pulse waveform produced by a Tesla-pulse forming network (PFN) type pulse generator. A single module composed of three involute dual-plate PFNs is designed, with a characteristic impedance of 2.44 Ω, an electrical length of 15 ns, and a sustaining voltage of 60 kV. The three involute dual-plate PFNs connected in parallel have the same impedance and electrical length. Due to the existed small inductance and capacitance per unit length in each involute dual-plate PFN, the upper cut-off frequency of the PFN is increased. As a result, the entire annular PFL has better high-frequency response capability. Meanwhile, the three dual-plate PFNs discharge in parallel, which is much closer to the coaxial output. The series connecting inductance between adjacent two modules is significantly reduced when the annular PFL modules are connected in series. The pulse waveform distortion is reduced when the pulse transfers along the modules. Finally, the shielding electrode structure is applied on both sides of the module. The electromagnetic field is restricted in the module when a single module discharges, and the electromagnetic coupling between the multi-stage annular PFLs is eliminated. Based on the principle of impedance matching between the multi-stage annular PFL and the coaxial PFL, the structural optimization design of a mixed PFL in a Tesla type pulse generator is completed with the transient field-circuit co-simulation method. The multi-stage annular PFL consists of 18 stage annular PFL modules in series, with the characteristic impedance of 44 Ω, the electrical length of 15 ns, and the sustaining voltage of 1 MV. The mixed PFL can generate quasi-square electrical pulses with a pulse width of 43 ns, and the fluctuation ratio of the pulse flat top is less than 8% when the pulse rise time is about 5 ns.

Compositional and strain analysis of In(Ga)N/GaN short period superlattices

NASA Astrophysics Data System (ADS)

Dimitrakopulos, G. P.; Vasileiadis, I. G.; Bazioti, C.; Smalc-Koziorowska, J.; Kret, S.; Dimakis, E.; Florini, N.; Kehagias, Th.; Suski, T.; Karakostas, Th.; Moustakas, T. D.; Komninou, Ph.

2018-01-01

Extensive high resolution transmission and scanning transmission electron microscopy observations were performed in In(Ga)N/GaN multi-quantum well short period superlattices comprising two-dimensional quantum wells (QWs) of nominal thicknesses 1, 2, and 4 monolayers (MLs) in order to obtain a correlation between their average composition, geometry, and strain. The high angle annular dark field Z-contrast observations were quantified for such layers, regarding the indium content of the QWs, and were correlated to their strain state using peak finding and geometrical phase analysis. Image simulations taking into thorough account the experimental imaging conditions were employed in order to associate the observed Z-contrast to the indium content. Energetically relaxed supercells calculated with a Tersoff empirical interatomic potential were used as the input for such simulations. We found a deviation from the tetragonal distortion prescribed by continuum elasticity for thin films, i.e., the strain in the relaxed cells was lower than expected for the case of 1 ML QWs. In all samples, the QW thickness and strain were confined in up to 2 ML with possible indium enrichment of the immediately abutting MLs. The average composition of the QWs was quantified in the form of alloy content.

Invention of the Annular Inductively Coupled Plasma as a Spectroscopic Source

NASA Astrophysics Data System (ADS)

Greenfield, Stanley

2000-05-01

This paper shows how experiments with electrical discharges from the 18th century onward led to their use as sources in atomic spectroscopy and how the invention of the annular inductively coupled plasma (ICP) some 30 years ago arose from the need to solve a problem that necessitated the use of a high-temperature source. The search for such a source followed a fairly logical pattern involving dc plasma jets and an ICP such as had been used by T. B. Reed for crystal growing. The ellipsoidal plasma used by Reed was not entirely suitable as a spectroscopic source, since the analytical sample either mixed with the plasma gases or passed around the plasma, resulting in matrix effects and a diminution in the emission. It is shown how suitable modification of the plasma torch with attention to gas flows made it possible to produce an annular or tunnel plasma through which the sample aerosol could be passed, resulting in an annular ICP with greatly improved spectroscopic properties. The further refinements to the source and ancillary equipment are also discussed.

Dryout-type critical heat flux in vertical upward annular flow: effects of entrainment rate, initial entrained fraction and diameter

NASA Astrophysics Data System (ADS)

Wu, Zan; Wadekar, Vishwas; Wang, Chenglong; Sunden, Bengt

2018-01-01

This study aims to reveal the effects of liquid entrainment, initial entrained fraction and tube diameter on liquid film dryout in vertical upward annular flow for flow boiling. Entrainment and deposition rates of droplets were included in mass conservation equations to estimate the local liquid film mass flux in annular flow, and the critical vapor quality at dryout conditions. Different entrainment rate correlations were evaluated using flow boiling data of water and organic liquids including n-pentane, iso-octane and R134a. Effect of the initial entrained fraction (IEF) at the churn-to-annular flow transition was also investigated. A transitional Boiling number was proposed to separate the IEF-sensitive region at high Boiling numbers and the IEF-insensitive region at low Boiling numbers. Besides, the diameter effect on dryout vapor quality was studied. The dryout vapor quality increases with decreasing tube diameter. It needs to be pointed out that the dryout characteristics of submillimeter channels might be different because of different mechanisms of dryout, i.e., drying of liquid film underneath long vapor slugs and flow boiling instabilities.

Air riding seal with purge cavity

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

Sexton, Thomas D; Mills, Jacob A

An air riding seal for a turbine in a gas turbine engine, where an annular piston is axial moveable within an annular piston chamber formed in a stator of the turbine and forms a seal with a surface on the rotor using pressurized air that forms a cushion in a pocket of the annular piston. A purge cavity is formed on the annular piston and is connected to a purge hole that extends through the annular piston to a lower pressure region around the annular piston or through the rotor to an opposite side. The annular piston is sealed alsomore » with inner and outer seals that can be a labyrinth seal to form an additional seal than the cushion of air in the pocket to prevent the face of the air riding seal from overheating.« less

Slab reformer

DOEpatents

Spurrier, Francis R.; DeZubay, Egon A.; Murray, Alexander P.; Vidt, Edward J.

1984-02-07

Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot comubstion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

Slab reformer

DOEpatents

Spurrier, Francis R.; DeZubay, Egon A.; Murray, Alexander P.; Vidt, Edward J.

1985-03-12

Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot combustion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

Pipe support

DOEpatents

Pollono, Louis P.

1979-01-01

A pipe support for high temperature, thin-walled piping runs such as those used in nuclear systems. A section of the pipe to be supported is encircled by a tubular inner member comprised of two walls with an annular space therebetween. Compacted load-bearing thermal insulation is encapsulated within the annular space, and the inner member is clamped to the pipe by a constant clamping force split-ring clamp. The clamp may be connected to pipe hangers which provide desired support for the pipe.

Slab reformer

NASA Technical Reports Server (NTRS)

Spurrier, Francis R. (Inventor); DeZubay, Egon A. (Inventor); Murray, Alexander P. (Inventor); Vidt, Edward J. (Inventor)

1984-01-01

Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot comubstion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

Analysis for leakage and rotordynamic coefficients of surface-roughened tapered annular gas seals

NASA Technical Reports Server (NTRS)

Nelson, C. C.

1984-01-01

The present analysis calculates the leakage and rotor-dynamic coefficients for tapered annular gas seals whose rotor and stator have been subjected to different surface roughness treatments. The analysis is demonstrated for the effects of changes in the Space Shuttle Main Engine High Pressure Oxygen Turbopump's turbine interstage seal length, taper, clearance, and fluid prerotation. It is noted that changes in these parameters generally resulted in major changes in leakage and rotordynamic coefficients.

Slab reformer

NASA Technical Reports Server (NTRS)

Spurrier, Francis R. (Inventor); DeZubay, Egon A. (Inventor); Murray, Alexander P. (Inventor); Vidt, Edward J. (Inventor)

1985-01-01

Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot combustion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

Multi-functional annular fairing for coupling launch abort motor to space vehicle

NASA Technical Reports Server (NTRS)

Camarda, Charles J. (Inventor); Scotti, Stephen J. (Inventor); Buning, Pieter G. (Inventor); Bauer, Steven X. S. (Inventor); Engelund, Walter C. (Inventor); Schuster, David M. (Inventor)

2011-01-01

An annular fairing having aerodynamic, thermal, structural and acoustic attributes couples a launch abort motor to a space vehicle having a payload of concern mounted on top of a rocket propulsion system. A first end of the annular fairing is fixedly attached to the launch abort motor while a second end of the annular fairing is attached in a releasable fashion to an aft region of the payload. The annular fairing increases in diameter between its first and second ends.

APPARATUS FOR PRODUCING HIGH VELOCITY SHOCK WAVES IN GASES

DOEpatents

Scott, F.R.; Josephson, V.

1960-02-01

>A device for producing a high-energy ionized gas region comprises an evacuated tapered insulating vessel and a substantially hemispherical insulating cap hermetically affixed to the large end of the vessel, an annular electrode having a diameter equal to and supported in the interior wall of the vessel at the large end and having a conductive portion inside the vessel, a second electrode supported at the small end of the vessel, means connected to the vessel for introducing a selected gas therein, a source of high potential having two poles. means for connecting one pole of the high potential source to the annular electrode, and means for connecting the other pole of the potential source to the second electrode.

Phase 3 experiments of the JAERI/USDOE collaborative program on fusion blanket neutronics. Volume 1: Experiment

NASA Astrophysics Data System (ADS)

Oyama, Yukio; Konno, Chikara; Ikeda, Yujiro; Maekawa, Fujio; Kosako, Kazuaki; Nakamura, Tomoo; Maekawa, Hiroshi; Youssef, Mahmoud Z.; Kumar, Anil; Abdou, Mohamed A.

1994-02-01

A pseudo-line source has been realized by using an accelerator based D-T point neutron source. The pseudo-line source is obtained by time averaging of continuously moving point source or by superposition of finely distributed point sources. The line source is utilized for fusion blanket neutronics experiments with an annular geometry so as to simulate a part of a tokamak reactor. The source neutron characteristics were measured for two operational modes for the line source, continuous and step-wide modes, with the activation foil and the NE213 detectors, respectively. In order to give a source condition for a successive calculational analysis on the annular blanket experiment, the neutron source characteristics was calculated by a Monte Carlo code. The reliability of the Monte Carlo calculation was confirmed by comparison with the measured source characteristics. The shape of the annular blanket system was a rectangular with an inner cavity. The annular blanket was consist of 15 mm-thick first wall (SS304) and 406 mm-thick breeder zone with Li2O at inside and Li2CO3 at outside. The line source was produced at the center of the inner cavity by moving the annular blanket system in the span of 2 m. Three annular blanket configurations were examined; the reference blanket, the blanket covered with 25 mm thick graphite armor and the armor-blanket with a large opening. The neutronics parameters of tritium production rate, neutron spectrum and activation reaction rate were measured with specially developed techniques such as multi-detector data acquisition system, spectrum weighting function method and ramp controlled high voltage system. The present experiment provides unique data for a higher step of benchmark to test a reliability of neutronics design calculation for a realistic tokamak reactor.

Polished Downhole Transducer Having Improved Signal Coupling

DOEpatents

Hall, David R.; Fox, Joe

2006-03-28

Apparatus and methods to improve signal coupling in downhole inductive transmission elements to reduce the dispersion of magnetic energy at the tool joints and to provide consistent impedance and contact between transmission elements located along the drill string. A transmission element for transmitting information between downhole tools is disclosed in one embodiment of the invention as including an annular core constructed of a magnetically conductive material. The annular core forms an open channel around its circumference and is configured to form a closed channel by mating with a corresponding annular core along an annular mating surface. The mating surface is polished to provide improved magnetic coupling with the corresponding annular core. An annular conductor is disposed within the open channel.

Axial Flow Conditioning Device for Mitigating Instabilities

NASA Technical Reports Server (NTRS)

Ahuja, Vineet (Inventor); Birkbeck, Roger M. (Inventor); Hosangadi, Ashvin (Inventor)

2017-01-01

A flow conditioning device for incrementally stepping down pressure within a piping system is presented. The invention includes an outer annular housing, a center element, and at least one intermediate annular element. The outer annular housing includes an inlet end attachable to an inlet pipe and an outlet end attachable to an outlet pipe. The outer annular housing and the intermediate annular element(s) are concentrically disposed about the center element. The intermediate annular element(s) separates an axial flow within the outer annular housing into at least two axial flow paths. Each axial flow path includes at least two annular extensions that alternately and locally direct the axial flow radially outward and inward or radially inward and outward thereby inducing a pressure loss or a pressure gradient within the axial flow. The pressure within the axial flow paths is lower than the pressure at the inlet end and greater than the vapor pressure for the axial flow. The invention minimizes fluidic instabilities, pressure pulses, vortex formation and shedding, and/or cavitation during pressure step down to yield a stabilized flow within a piping system.

Three cases of subcutaneous granuloma annulare of the penis: a rare presentation of a common disease.

PubMed

Toepfer, Nicholas J; Wessner, Scott R; Elston, Dirk M; Simmons, Jennifer; Sumfest, Joel M

2011-09-01

To describe three patients who presented to a single institution within four years of each other with isolated granuloma annulare of the penis. Granuloma annulare is an inflammatory disease of the dermis that can affect men of any age including childhood. Granuloma annulare of the penis is a remarkably uncommon presentation with only 12 cases previously reported. A retrospective review of pathologic records was conducted confirming three cases of penile granuloma annulare diagnosed at our institution. The three cases are described in detail including the history, presentation, histological findings and treatment of each patient. The clinical variants, characteristic histology, classic clinical presentation, differential diagnosis and recurrence following surgery of granuloma annulare are reviewed. We describe three individuals from a single institution with isolated granuloma annulare of the penis suggesting this condition is more common than previously thought. Patients with penile granuloma annulare may present to practicing urologists and it is important to be familiar with this idiopathic subcutaneous disorder in order to avoid unnecessary aggressive surgery. Copyright © 2011 Elsevier Inc. All rights reserved.

UF.sub.6 -Recovery process utilizing desublimation

DOEpatents

Eby, Robert S.; Stephenson, Michael J.; Andrews, Deborah H.; Hamilton, Thomas H.

1985-01-01

The invention is a UF.sub.6 -recovery process of the kind in which a stream of substantially pure gaseous UF.sub.6 is directed through an externally chilled desublimer to convert the UF.sub.6 directly to an annular solid ring adhering to the interior wall of the desublimer. After accumulation of a desired amount of solid UF.sub.6, the desublimer is heated to liquefy the solid. Subsequently, the liquid is recovered from the desublimer. It has been found that during the heating operation the desublimer is subjected to excessive mechanical stresses. In addition, it has been found that the incorporation of a very small percentage of relatively noncondensable, nonreactive gas (e.g., nitrogen) in the UF.sub.6 input to the desublimer effects significant decreases in the stresses generated during the subsequent melting operation. This modification to the process provides valuable advantages in terms of reduced hazard, lower operating costs for the desublimer, and increased service life for the desublimer and its auxiliaries. The new process is especially suitable for the recovery of enriched UF.sub.6 from high-speed UF.sub.6 gas-centrifuge cascades.

UF/sub 6/-recovery process utilizing desublimation

DOEpatents

Eby, R.S.; Stephenson, M.J.; Andrews, D.H.; Hamilton, T.H.

1983-12-21

The invention is a UF/sub 6/-recovery process of the kind in which a stream of substantially pure gaseous UF/sub 6/ is directed through an externally chilled desublimer to convert the UF/sub 6/ directly to an annular solid ring adhering to the interior wall of the desublimer. After accumulation of a desired amount of solid UF/sub 6/, the desublimer is heated to liquefy the solid. Subsequently, the liquid is recovered from the desublimer. It has been found that during the heating operation the desublimer is subjected to excessive mechanical stresses. In addition, it has been found that the incorporation of a very small percentage of relatively noncondensable, nonreactive gas (e.g., nitrogen) in the UF/sub 6/ input to the desublimer effects significant decreases in the stresses generated during the subsequent melting operation. This modification to the process provides valuable advantages in terms of reduced hazard, lower operating costs for the desublimer, and increased service life for the desublimer and its auxiliaries. The new process is especially suitable for the recovery of enriched UF/sub 6/ from high-speed UF/sub 6/ gas-centrifuge cascades.

Slab reformer

DOEpatents

Spurrier, F.R.; DeZubay, E.A.; Murray, A.P.; Vidt, E.J.

1984-02-07

Slab-shaped high efficiency catalytic reformer configurations are disclosed particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot combustion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant. 14 figs.

Gust Response Analysis of a Turbine Cascade

NASA Technical Reports Server (NTRS)

Gorla, R. S. R.; Reddy, T. S. R.; Reddy, D. R.; Kurkov, A. P.

2001-01-01

A study was made of the gust response of an annular turbine cascade using a two-dimensional Navier Stokes code. The time-marching CFD code, NPARC, was used to calculate the unsteady forces due to the fluid flow. The computational results were compared with a previously published experimental data for the annular cascade reported in the literature. Reduced frequency, Mach number and angle of incidence were varied independently and the gust velocity was sinusoidal. For the high inlet velocity case, the cascade was nearly choked.

High Thrust-to-Power Annular Engine Technology

NASA Technical Reports Server (NTRS)

Patterson, Michael J.; Thomas, Robert E.; Crofton, Mark W.; Young, Jason A.; Foster, John E.

2015-01-01

Gridded ion engines have the highest efficiency and total impulse of any mature electric propulsion technology, and have been successfully implemented for primary propulsion in both geocentric and heliocentric environments with excellent ground/in-space correlation of performance. However, they have not been optimized to maximize thrust-to-power, an important parameter for Earth orbit transfer applications. This publication discusses technology development work intended to maximize this parameter. These activities include investigating the capabilities of a non-conventional design approach, the annular engine, which has the potential of exceeding the thrust-to-power of other EP technologies. This publication discusses the status of this work, including the fabrication and initial tests of a large-area annular engine. This work is being conducted in collaboration among NASA Glenn Research Center, The Aerospace Corporation, and the University of Michigan.

High Thrust-to-Power Annular Engine Technology

NASA Technical Reports Server (NTRS)

Patterson, Michael; Thomas, Robert; Crofton, Mark; Young, Jason A.; Foster, John E.

2015-01-01

Gridded ion engines have the highest efficiency and total impulse of any mature electric propulsion technology, and have been successfully implemented for primary propulsion in both geocentric and heliocentric environments with excellent ground-in-space correlation of performance. However, they have not been optimized to maximize thrust-to-power, an important parameter for Earth orbit transfer applications. This publication discusses technology development work intended to maximize this parameter. These activities include investigating the capabilities of a non-conventional design approach, the annular engine, which has the potential of exceeding the thrust-to-power of other EP technologies. This publication discusses the status of this work, including the fabrication and initial tests of a large-area annular engine. This work is being conducted in collaboration among NASA Glenn Research Center, The Aerospace Corporation, and the University of Michigan.

Centrifugally activated bearing for high-speed rotating machinery

DOEpatents

Post, Richard F.

1994-01-01

A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation.

NASA/General Electric broad-specification fuels combustion technology program - Phase I results and status

NASA Technical Reports Server (NTRS)

Dodds, W. J.; Ekstedt, E. E.; Bahr, D. W.; Fear, J. S.

1982-01-01

A program is being conducted to develop the technology required to utilize fuels with broadened properties in aircraft gas turbine engines. The first phase of this program consisted of the experimental evaluation of three different combustor concepts to determine their potential for meeting several specific emissions and performance goals, when operated on broadened property fuels. The three concepts were a single annular combustor; a double annular combustor; and a short single annular combustor with variable geometry. All of these concepts were sized for the General Electric CF6-80 engine. A total of 24 different configurations of these concepts were evaluated in a high pressure test facility, using four test fuels having hydrogen contents between 11.8 and 14%. Fuel effects on combustor performance, durability and emissions, and combustor design features to offset these effects were demonstrated.

Annular pancreas

MedlinePlus

... page: //medlineplus.gov/ency/article/001142.htm Annular pancreas To use the sharing features on this page, please enable JavaScript. An annular pancreas is a ring of pancreatic tissue that encircles ...

Boron filled siloxane polymers for radiation shielding

NASA Astrophysics Data System (ADS)

Labouriau, Andrea; Robison, Tom; Shonrock, Clinton; Simmonds, Steve; Cox, Brad; Pacheco, Adam; Cady, Carl

2018-03-01

The purpose of the present work was to evaluate changes to structure-property relationships of 10B filled siloxane-based polymers when exposed to nuclear reactor radiation. Highly filled polysiloxanes were synthesized with the intent of fabricating materials that could shield high neutron fluences. The newly formulated materials consisted of cross-linked poly-diphenyl-methylsiloxane filled with natural boron and carbon nanofibers. This polymer was chosen because of its good thermal and chemical stabilities, as well as resistance to ionizing radiation thanks to the presence of aromatic groups in the siloxane backbone. Highly isotopically enriched 10B filler was used to provide an efficient neutron radiation shield, and carbon nanofibers were added to improve mechanical strength. This novel polymeric material was exposed in the Annular Core Research Reactor (ACRR) at Sandia National Labs to five different neutron/gamma fluxes consisting of very high neutron fluences within very short time periods. Thermocouples placed on the specimens recorded in-situ temperature changes during radiation exposure, which agreed well with those obtained from our MCNP simulations. Changes in the microstructural, thermal, chemical, and mechanical properties were evaluated by SEM, DSC, TGA, FT-IR NMR, solvent swelling, and uniaxial compressive load measurements. Our results demonstrate that these newly formulated materials are well-suitable to be used in applications that require exposure to different types of ionizing conditions that take place simultaneously.

Boron Filled Siloxane Polymers for Radiation Shielding

DOE PAGES

Labouriau, Andrea; Robison, Tom; Shonrock, Clinton Otto; ...

2017-09-01

The purpose of the present work was to evaluate changes to structure-property relationships of 10B filled siloxane-based polymers when exposed to nuclear reactor radiation. Highly filled polysiloxanes were synthesized with the intent of fabricating materials that could shield high neutron fluences. The newly formulated materials consisted of cross-linked poly-diphenyl-methylsiloxane filled with natural boron and carbon nanofibers. This polymer was chosen because of its good thermal and chemical stabilities, as well as resistance to ionizing radiation thanks to the presence of aromatic groups in the siloxane backbone. Highly isotopically enriched 10B filler was used to provide an efficient neutron radiation shield,more » and carbon nanofibers were added to improve mechanical strength. This novel polymeric material was exposed in the Annular Core Research Reactor (ACRR) at Sandia National Labs to five different neutron/gamma fluxes consisting of very high neutron fluences within very short time periods. Thermocouples placed on the specimens recorded in-situ temperature changes during radiation exposure, which agreed well with those obtained from our MCNP simulations. Changes in the microstructural, thermal, chemical, and mechanical properties were evaluated by SEM, DSC, TGA, FT-IR NMR, solvent swelling, and uniaxial compressive load measurements. In conclusion, our results demonstrate that these newly formulated materials are well-suitable to be used in applications that require exposure to different types of ionizing conditions that take place simultaneously.« less

Boron Filled Siloxane Polymers for Radiation Shielding

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

Labouriau, Andrea; Robison, Tom; Shonrock, Clinton Otto

The purpose of the present work was to evaluate changes to structure-property relationships of 10B filled siloxane-based polymers when exposed to nuclear reactor radiation. Highly filled polysiloxanes were synthesized with the intent of fabricating materials that could shield high neutron fluences. The newly formulated materials consisted of cross-linked poly-diphenyl-methylsiloxane filled with natural boron and carbon nanofibers. This polymer was chosen because of its good thermal and chemical stabilities, as well as resistance to ionizing radiation thanks to the presence of aromatic groups in the siloxane backbone. Highly isotopically enriched 10B filler was used to provide an efficient neutron radiation shield,more » and carbon nanofibers were added to improve mechanical strength. This novel polymeric material was exposed in the Annular Core Research Reactor (ACRR) at Sandia National Labs to five different neutron/gamma fluxes consisting of very high neutron fluences within very short time periods. Thermocouples placed on the specimens recorded in-situ temperature changes during radiation exposure, which agreed well with those obtained from our MCNP simulations. Changes in the microstructural, thermal, chemical, and mechanical properties were evaluated by SEM, DSC, TGA, FT-IR NMR, solvent swelling, and uniaxial compressive load measurements. In conclusion, our results demonstrate that these newly formulated materials are well-suitable to be used in applications that require exposure to different types of ionizing conditions that take place simultaneously.« less

Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures

NASA Technical Reports Server (NTRS)

Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

2007-01-01

Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 < r* < 0.83. These smooth tube data may serve as a reference to the heat transfer and pressure drop performance in annuli, tubes, and channels having helixes or spacer ribs, or other surfaces.

Universal cell frame for high-pressure water electrolyzer and electrolyzer including the same

DOEpatents

Schmitt, Edwin W.; Norman, Timothy J.

2013-01-08

Universal cell frame generic for use as an anode frame and as a cathode frame in a water electrolyzer. According to one embodiment, the universal cell frame includes a unitary annular member having a central opening. Four trios of transverse openings are provided in the annular member, each trio being spaced apart by about 90 degrees. A plurality of internal radial passageways fluidly interconnect the central opening and each of the transverse openings of two diametrically-opposed trios of openings, the other two trios of openings lacking corresponding radial passageways. Sealing ribs are provided on the top and bottom surfaces of the annular member. The present invention is also directed at a water electrolyzer that includes two such cell frames, one being used as the anode frame and the other being used as the cathode frame, the cathode frame being rotated 90 degrees relative to the anode frame.

Centrifugally activated bearing for high-speed rotating machinery

DOEpatents

Post, R.F.

1994-02-15

A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation. 4 figures.

Use of an Annular Silicon Drift Detector (SDD) Versus a Conventional SDD Makes Phase Mapping a Practical Solution for Rare Earth Mineral Characterization.

PubMed

Teng, Chaoyi; Demers, Hendrix; Brodusch, Nicolas; Waters, Kristian; Gauvin, Raynald

2018-06-04

A number of techniques for the characterization of rare earth minerals (REM) have been developed and are widely applied in the mining industry. However, most of them are limited to a global analysis due to their low spatial resolution. In this work, phase map analyses were performed on REM with an annular silicon drift detector (aSDD) attached to a field emission scanning electron microscope. The optimal conditions for the aSDD were explored, and the high-resolution phase maps generated at a low accelerating voltage identify phases at the micron scale. In comparisons between an annular and a conventional SDD, the aSDD performed at optimized conditions, making the phase map a practical solution for choosing an appropriate grinding size, judging the efficiency of different separation processes, and optimizing a REM beneficiation flowsheet.

Testing large aspheric surfaces with complementary annular subaperture interferometric method

NASA Astrophysics Data System (ADS)

Hou, Xi; Wu, Fan; Lei, Baiping; Fan, Bin; Chen, Qiang

2008-07-01

Annular subaperture interferometric method has provided an alternative solution to testing rotationally symmetric aspheric surfaces with low cost and flexibility. However, some new challenges, particularly in the motion and algorithm components, appear when applied to large aspheric surfaces with large departure in the practical engineering. Based on our previously reported annular subaperture reconstruction algorithm with Zernike annular polynomials and matrix method, and the experimental results for an approximate 130-mm diameter and f/2 parabolic mirror, an experimental investigation by testing an approximate 302-mm diameter and f/1.7 parabolic mirror with the complementary annular subaperture interferometric method is presented. We have focused on full-aperture reconstruction accuracy, and discuss some error effects and limitations of testing larger aspheric surfaces with the annular subaperture method. Some considerations about testing sector segment with complementary sector subapertures are provided.

Electron beam diagnostic system using computed tomography and an annular sensor

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

Elmer, John W.; Teruya, Alan T.

2015-08-11

A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by themore » annular sensor structure.« less

Electron beam diagnostic system using computed tomography and an annular sensor

DOEpatents

Elmer, John W.; Teruya, Alan T.

2014-07-29

A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

Arthroscopic Treatment of Annular Drive Through and Radial Lateral Collateral Ligament Articular-Side Tear of the Elbow.

PubMed

Arrigoni, Paolo; D'Ambrosi, Riccardo; Randelli, Pietro

2015-12-01

An elongation or partial articular-sided tear of the radial lateral collateral ligament (R-LCL) is a rare injury causing disability and instability of the elbow. In our experience this condition is often associated with a pathologic sign of the annular ligament named the "annular drive through" caused by a redundancy of the ligament. The benefits of performing an arthroscopic procedure for surgical stabilization of the R-LCL include smaller incisions with less soft-tissue dissection, better visualization of the joint, better repair accessibility, and elimination of the annular drive-through sign. The main steps of the operation are as follows: evaluation of annular drive through, inspection of the radial side of the joint, anterior capsulotomy, insertion of a suture anchor through the anterolateral portal, shuttling of the suture anchor through the ligament, and elimination of the annular drive-through sign. By use of this technique, it is possible to repair a lesion of the R-LCL with a suture anchor that ensures an anatomic repair and, at the same time, returns the annular ligament to its physiological tension.

Atomic bonding effects in annular dark field scanning transmission electron microscopy. II. Experiments

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

Odlyzko, Michael L.; Held, Jacob T.; Mkhoyan, K. Andre, E-mail: mkhoyan@umn.edu

2016-07-15

Quantitatively calibrated annular dark field scanning transmission electron microscopy (ADF-STEM) imaging experiments were compared to frozen phonon multislice simulations adapted to include chemical bonding effects. Having carefully matched simulation parameters to experimental conditions, a depth-dependent bonding effect was observed for high-angle ADF-STEM imaging of aluminum nitride. This result is explained by computational predictions, systematically examined in the preceding portion of this study, showing the propagation of the converged STEM beam to be highly sensitive to net interatomic charge transfer. Thus, although uncertainties in experimental conditions and simulation accuracy remain, the computationally predicted experimental bonding effect withstands the experimental testing reportedmore » here.« less

Photoacoustic Imaging of Animals with an Annular Transducer Array

NASA Astrophysics Data System (ADS)

Yang, Di-Wu; Zhou, Zhi-Bin; Zeng, Lv-Ming; Zhou, Xin; Chen, Xing-Hui

2014-07-01

A photoacoustic system with an annular transducer array is presented for rapid, high-resolution photoacoustic tomography of animals. An eight-channel data acquisition system is applied to capture the photoacoustic signals by using multiplexing and the total time of data acquisition and transferring is within 3 s. A limited-view filtered back projection algorithm is used to reconstruct the photoacoustic images. Experiments are performed on a mouse head and a rabbit head and clear photoacoustic images are obtained. The experimental results demonstrate that this imaging system holds the potential for imaging the human brain.

Quiet Clean Short-haul Experimental Engine (QCSEE). Double-annular clean combustor technology development report

NASA Technical Reports Server (NTRS)

Bahr, D. W.; Burrus, D. L.; Sabla, P. E.

1979-01-01

A sector combustor technology development program was conducted to define an advanced double annular dome combustor sized for use in the quiet clean short haul experimental engine (QCSEE). A design which meets the emission goals, and combustor performance goals of the QCSEE engine program was developed. Key design features were identified which resulted in substantial reduction in carbon monoxide and unburned hydrocarbon emission levels at ground idle operating conditions, in addition to very low nitric oxide emission levels at high power operating conditions. Their significant results are reported.

Annular Suspension and Pointing System (ASPS) magnetic rotary joint

NASA Technical Reports Server (NTRS)

Smith, W. E.; Quach, W.; Thomas, W.

1993-01-01

The Annular Suspension and Pointing System (ASPS) is a prototype of flight hardware for a high-accuracy space payload pointing mount. The long term project objective is to perform modifications and implement improvements to the existing ASPS in hopes of recommission. Also, new applications will be investigated for this technology. This report will focus on the first aspect of this overall goal, to establish operation of a single bearing station. Presented is an overview of the system history and bearing operation followed by the processes, results, and status of the single bearing study.

Coaxial fuel and air premixer for a gas turbine combustor

DOEpatents

York, William D; Ziminsky, Willy S; Lacy, Benjamin P

2013-05-21

An air/fuel premixer comprising a peripheral wall defining a mixing chamber, a nozzle disposed at least partially within the peripheral wall comprising an outer annular wall spaced from the peripheral wall so as to define an outer air passage between the peripheral wall and the outer annular wall, an inner annular wall disposed at least partially within and spaced from the outer annular wall, so as to define an inner air passage, and at least one fuel gas annulus between the outer annular wall and the inner annular wall, the at least one fuel gas annulus defining at least one fuel gas passage, at least one air inlet for introducing air through the inner air passage and the outer air passage to the mixing chamber, and at least one fuel inlet for injecting fuel through the fuel gas passage to the mixing chamber to form an air/fuel mixture.

Percutaneous endoscopic intra-annular subligamentous herniotomy for large central disc herniation: a technical case report.

PubMed

Lee, Sang-Ho; Choi, Kyung-Chul; Baek, Oon Ki; Kim, Ho Jin; Yoo, Seung-Hwa

2014-04-01

Technical case report. To describe the novel technique of percutaneous endoscopic herniotomy using a unilateral intra-annular subligamentous approach for the treatment of large centrally herniated discs. Open discectomy for large central disc herniations may have poor long-term prognosis due to heavy loss of intervertebral disc tissue, segmental instability, and recurrence of pain. Six consecutive patients who presented with back and leg pain, and/or weakness due to a large central disc herniation were treated using percutaneous endoscopic herniotomy with a unilateral intra-annular subligamentous approach. The patients experienced relief of symptoms and intervertebral disc spaces were well maintained. The annular defects were noted to be in the process of healing and recovery. Percutaneous endoscopic unilateral intra-annular subligamentous herniotomy was an effective and affordable minimally invasive procedure for patients with large central disc herniations, allowing preservation of nonpathological intradiscal tissue through a concentric outer-layer annular approach.

Method of making an aero-derivative gas turbine engine

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

Wiebe, David J.

A method of making an aero-derivative gas turbine engine (100) is provided. A combustor outer casing (68) is removed from an existing aero gas turbine engine (60). An annular combustor (84) is removed from the existing aero gas turbine engine. A first row of turbine vanes (38) is removed from the existing aero gas turbine engine. A can annular combustor assembly (122) is installed within the existing aero gas turbine engine. The can annular combustor assembly is configured to accelerate and orient combustion gasses directly onto a first row of turbine blades of the existing aero gas turbine engine. Amore » can annular combustor assembly outer casing (108) is installed to produce the aero-derivative gas turbine engine (100). The can annular combustor assembly is installed within an axial span (85) of the existing aero gas turbine engine vacated by the annular combustor and the first row of turbine vanes.« less

High temperature solid electrolyte fuel cell configurations and interconnections

DOEpatents

Isenberg, Arnold O.

1984-01-01

High temperature fuel cell configurations and interconnections are made including annular cells having a solid electrolyte sandwiched between thin film electrodes. The cells are electrically interconnected along an elongated axial outer surface.

Processing of Bulk YBa2Cu3O(7-x) High Temperature Superconductor Materials for Gravity Modification Experiments and Performance Under AC Levitation

NASA Technical Reports Server (NTRS)

Koczor, Ronald; Noever, David; Hiser, Robert

1999-01-01

We have previously reported results using a high precision gravimeter to probe local gravity changes in the neighborhood of bulk-processed high temperature superconductor disks. Others have indicated that large annular disks (on the order of 25cm diameter) and AC levitation fields play an essential role in their observed experiments. We report experiments in processing such large bulk superconductors. Successful results depend on material mechanical characteristics, and pressure and heat treat protocols. Annular disks having rough dimensions of 30cm O.D., 7cm I.D. and 1 cm thickness have been routinely fabricated and tested under AC levitation fields ranging from 45 to 300OHz. Implications for space transportation initiatives and power storage flywheel technology will be discussed.

Extended residence time centrifugal contactor design modification and centrifugal contactor vane plate valving apparatus for extending mixing zone residence time

DOEpatents

Wardle, Kent E.

2017-06-06

The present invention provides an annular centrifugal contactor, having a housing adapted to receive a plurality of flowing liquids; a rotor on the interior of the housing; an annular mixing zone, wherein the annular mixing zone has a plurality of fluid retention reservoirs with ingress apertures near the bottom of the annular mixing zone and egress apertures located above the ingress apertures of the annular mixing zone; and an adjustable vane plate stem, wherein the stem can be raised to restrict the flow of a liquid into the rotor or lowered to increase the flow of the liquid into the rotor.

Micromachined High Frequency PMN-PT/Epoxy 1-3 Composite Ultrasonic Annular Array

PubMed Central

Liu, Changgeng; Djuth, Frank; Li, Xiang; Chen, Ruimin; Zhou, Qifa; Shung, K. Kirk

2013-01-01

This paper reports the design, fabrication, and performance of miniature micromachined high frequency PMN-PT/epoxy 1-3 composite ultrasonic annular arrays. The PMN-PT single crystal 1-3 composites were made with micromachining techniques. The area of a single crystal pillar was 9 μm × 9 μm. The width of the kerf among pillars was ~ 5 μm and the kerfs were filled with a polymer. The composite thickness was 25 μm. A six-element annular transducer of equal element area of 0.2 mm2 with 16 μm kerf widths between annuli was produced. The aperture size the array transducer is about 1.5 mm in diameter. A novel electrical interconnection strategy for high density array elements was implemented. After the transducer was attached to the electric connection board and packaged, the array transducer was tested in a pulse/echo arrangement, whereby the center frequency, bandwidth, two-way insertion loss (IL), and cross talk between adjacent elements were measured for each annulus. The center frequency was 50 MHz and -6 dB bandwidth was 90%. The average insertion loss was 19.5 dB at 50 MHz and the crosstalk between adjacent elements was about -35 dB. The micromachining techniques described in this paper are promising for the fabrication of other types of high frequency transducers e.g. 1D and 2D arrays. PMID:22119324

Annular Solar Eclipse of 10 May 1994

NASA Technical Reports Server (NTRS)

Espenak, Fred; Anderson, Jay

1993-01-01

An annular eclipse of the Sun will be widely visible from the Western Hemisphere on 10 May 1994. The path of the Moon's shadow passes through Mexico, the United States of America, maritime Canada, the North Atlantic, the Azores and Morocco. Detailed predictions for this event are presented and include tables of geographic coordinates of the annular path, local circumstances for hundreds of cities, maps of the path of annular and partial eclipse, weather prospects, and the lunar limb profile.

Laser-induced retinal damage thresholds for annular retinal beam profiles

NASA Astrophysics Data System (ADS)

Kennedy, Paul K.; Zuclich, Joseph A.; Lund, David J.; Edsall, Peter R.; Till, Stephen; Stuck, Bruce E.; Hollins, Richard C.

2004-07-01

The dependence of retinal damage thresholds on laser spot size, for annular retinal beam profiles, was measured in vivo for 3 μs, 590 nm pulses from a flashlamp-pumped dye laser. Minimum Visible Lesion (MVL)ED50 thresholds in rhesus were measured for annular retinal beam profiles covering 5, 10, and 20 mrad of visual field; which correspond to outer beam diameters of roughly 70, 160, and 300 μm, respectively, on the primate retina. Annular beam profiles at the retinal plane were achieved using a telescopic imaging system, with the focal properties of the eye represented as an equivalent thin lens, and all annular beam profiles had a 37% central obscuration. As a check on experimental data, theoretical MVL-ED50 thresholds for annular beam exposures were calculated using the Thompson-Gerstman granular model of laser-induced thermal damage to the retina. Threshold calculations were performed for the three experimental beam diameters and for an intermediate case with an outer beam diameter of 230 μm. Results indicate that the threshold vs. spot size trends, for annular beams, are similar to the trends for top hat beams determined in a previous study; i.e., the threshold dose varies with the retinal image area for larger image sizes. The model correctly predicts the threshold vs. spot size trends seen in the biological data, for both annular and top hat retinal beam profiles.

Damping device for a stationary labyrinth seal

NASA Technical Reports Server (NTRS)

El-Aini, Yehia M. (Inventor); Mitchell, William S. (Inventor); Roberts, Lawrence P. (Inventor); Montgomery, Stuart K. (Inventor); Davis, Gary A. (Inventor)

2010-01-01

A stationary labyrinth seal system includes a seal housing having an annular cavity, a plurality of damping devices, and a retaining ring. The damping devices are positioned within the annular cavity and are maintained within the annular cavity by the retaining ring.

Experimental study on the void fraction of air-water two-phase flow in a horizontal circular minichannel

NASA Astrophysics Data System (ADS)

Sudarja, Indarto, Deendarlianto, Haq, Aqli

2016-06-01

Void fraction is an important parameter in two-phase flow. In the present work, the adiabatic two-phase air-water flow void fraction in a horizontal minichannel has been studied experimentally. A transparent circular channel with 1.6 mm inner diameter was employed as the test section. Superficial gas and liquid velocities were varied in the range of 1.25 - 66.3 m/s and 0.033 - 4.935 m/s, respectively. Void fraction data were obtained by analyzing the flow images being captured by using a high-speed camera. Here, the homogeneous (β) and the measured void fractions (ɛ), respectively, were compared to the existing correlations. It was found that: (1) for the bubbly and slug flows, the void fractions increases with the increase of JG, (2) for churn, slug-annular, and annular flow patterns, there is no specific correlation between JG and void fraction was observed due to effect of the slip between gas and liquid, and (3) whilst for bubbly and slug flows the void fractions are close to homogeneous line, for churn, annular, and slug-annular flows are far below the homogeneous line. It indicates that the slip ratios for the second group of flow patterns are higher than unity.

Jet Mixing and Emission Characteristics of Transverse Jets in Annular and Cylindrical Confined Crossflow

NASA Technical Reports Server (NTRS)

Bain, D. B.; Smith, C. E.; Holdeman, J. D.

1995-01-01

Three dimensional turbulent reacting CFD analyses were performed on transverse jets injected into annular and cylindrical (can) confined crossflows. The goal was to identify and assess mixing differences between annular and can geometries. The approach taken was to optimize both annular and can configurations by systematically varying orifice spacing until lowest emissions were achieved, and then compare the results. Numerical test conditions consisted of a jet-to-mainstream mass-flow ratio of 3.2 and a jet-to-mainstream momentum-flux ratio (J) of 30. The computational results showed that the optimized geometries had similar emission levels at the exit of the mixing section although the annular configuration did mix-out faster. For lowest emissions, the density correlation parameter (C = (S/H) square root of J) was 2.35 for the annular geometry and 3.5 for the can geometry. For the annular geometry, the constant was about twice the value seen for jet mixing at low mass-flow ratios (i.e., MR less than 0.5). For the can geometry, the constant was about 1 1/2 times the value seen for low mass-flow ratios.

Molecular mechanisms regulating formation, trafficking and processing of annular gap junctions.

PubMed

Falk, Matthias M; Bell, Cheryl L; Kells Andrews, Rachael M; Murray, Sandra A

2016-05-24

Internalization of gap junction plaques results in the formation of annular gap junction vesicles. The factors that regulate the coordinated internalization of the gap junction plaques to form annular gap junction vesicles, and the subsequent events involved in annular gap junction processing have only relatively recently been investigated in detail. However it is becoming clear that while annular gap junction vesicles have been demonstrated to be degraded by autophagosomal and endo-lysosomal pathways, they undergo a number of additional processing events. Here, we characterize the morphology of the annular gap junction vesicle and review the current knowledge of the processes involved in their formation, fission, fusion, and degradation. In addition, we address the possibility for connexin protein recycling back to the plasma membrane to contribute to gap junction formation and intercellular communication. Information on gap junction plaque removal from the plasma membrane and the subsequent processing of annular gap junction vesicles is critical to our understanding of cell-cell communication as it relates to events regulating development, cell homeostasis, unstable proliferation of cancer cells, wound healing, changes in the ischemic heart, and many other physiological and pathological cellular phenomena.

Kelly mud saver valve sub

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

Reddoch, J.A.

1986-12-02

A mud saver valve is described for preventing drilling mud from escaping from a kelly when a drill string is broken below the kelly, the valve comprising: a tubular valve body having first and second ends, the first end being provided with means for attachment in fluid communicating relationship with the kelly, the second end being provided with means for attachment to the drill string; an annular seat fixed in the interior of the valve body adjacent its first end; a tubular closure member within the valve body. The closure member is provided with a selectively closed seating end formore » seating in valve closing engagement with the annular seat, an open non-seating end in fluid communicating relationship with the drill string, and an annular expansion in the outer diameter of the closure member adjacent the seating end; a top and bottom spacer ring disposed in sliding relationship around the tubular closure member intermediate the annular expansion and the non-seating end of the closure member. The spacer ring and annular expansion cooperatively define an annular chamber around the closure member; and a helical spring disposed around the closure member towards the annular seat.« less

Adaptive optics scanning ophthalmoscopy with annular pupils

PubMed Central

Sulai, Yusufu N.; Dubra, Alfredo

2012-01-01

Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections. PMID:22808435

Adaptive optics scanning ophthalmoscopy with annular pupils.

PubMed

Sulai, Yusufu N; Dubra, Alfredo

2012-07-01

Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections.

Do CTA measurements of annular diameter, perimeter and area result in different TAVI prosthesis sizes?

PubMed

Horehledova, Barbora; Mihl, Casper; Hendriks, Babs M F; Eijsvoogel, Nienke G; Vainer, Jindrich; Veenstra, Leo F; Wildberger, Joachim E; Das, Marco

2018-06-16

Incorrect prosthesis size has direct impact on patient outcome after transcatheter aortic valve implantation (TAVI) procedure. Currently, annular diameter, area or perimeter may be used for prosthesis size selection. The aim was to evaluate whether the use different annular dimensions would result in the selection of different prosthesis sizes, when assessed in the same TAVI-candidate during the same phase of a cardiac cycle. Fifty consecutive TAVI-candidates underwent retrospectively ECG-gated computed tomography angiography (CTA). Aortic root dimensions were assessed in the 20% phase of the R-R interval. Annular short diameter, perimeter and area were used to select the prosthesis size, based on the industry recommendations for a self-expandable (Medtronic CoreValve; MCV) and balloon-expandable (Edwards Sapien XT Valve; ESV) valve. Complete agreement on selected prosthesis size amongst all three annular dimensions was observed in 62% (31/50; ESV) and 30% (15/50; MCV). Short aortic annulus measurement resulted in a smaller prosthesis size in 20% (10/50; ESV) and in 60% of cases (30/50; MCV) compared to the size suggested by both annular perimeter and area. In 18% (9/50; ESV) and 10% of cases (5/50; MCV) a larger prosthesis would have been selected based on annular perimeter compared to annular diameter and area. Prosthesis size derived from area was always in agreement with at least one other parameter in all cases. Aortic annulus area appears to be the most robust parameter for TAVI-prosthesis size selection, regardless of the specific prosthesis size. Short aortic annulus diameter may underestimate the prosthesis size, while use of annular perimeter may lead to size overestimation in some cases.

Entrance and exit region friction factor models for annular seal analysis. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Elrod, David Alan

1988-01-01

The Mach number definition and boundary conditions in Nelson's nominally-centered, annular gas seal analysis are revised. A method is described for determining the wall shear stress characteristics of an annular gas seal experimentally. Two friction factor models are developed for annular seal analysis; one model is based on flat-plate flow theory; the other uses empirical entrance and exit region friction factors. The friction factor predictions of the models are compared to experimental results. Each friction model is used in an annular gas seal analysis. The seal characteristics predicted by the two seal analyses are compared to experimental results and to the predictions of Nelson's analysis. The comparisons are for smooth-rotor seals with smooth and honeycomb stators. The comparisons show that the analysis which uses empirical entrance and exit region shear stress models predicts the static and stability characteristics of annular gas seals better than the other analyses. The analyses predict direct stiffness poorly.

Formation of a quasi-hollow beam of high-energy heavy ions using a multicell resonance RF deflector

NASA Astrophysics Data System (ADS)

Minaev, S. A.; Sitnikov, A. L.; Golubev, A. A.; Kulevoy, T. V.

2012-09-01

The generation of matter in an extreme state with precisely measurable parameters is of great interest for contemporary physics. One way of obtaining such a state is to irradiate the end of a hollow cylindrical shell at the center of which a test material is kept at a temperature of several Kelvin by an annular beam of high-energy heavy ions. Under the action of the beam, the shell starts explosively expanding both outwards and inwards, compressing the material to an extremely high pressure without subjecting it to direct heating. A method of producing a hollow cylindrical beam of high-energy heavy ions using a resonance rf deflector is described. The deflection of the beam in two transverse directions by means of an rf electric field allows it to rotate about the longitudinal axis and irradiate an annular domain on the end face of the target.

ASPS performance with large payloads onboard the Shuttle Orbiter. [Annular Suspension and Pointing System

NASA Technical Reports Server (NTRS)

Keckler, C. R.

1980-01-01

A high fidelity digital computer simulation was used to establish the viability of the Annular Suspension and Pointing System (ASPS) for satisfying the pointing and stability requirements of facility class payloads, such as the Solar Optical Telescope, when subjected to the Orbiter disturbance environment. The ASPS and its payload were subjected to disturbances resulting from crew motions in the Orbiter aft flight deck and VRCS thruster firings. Worst case pointing errors of 0.005 arc seconds were experienced under the disturbance environment simulated; this is well within the 0.08 arc seconds requirement specified by the payload.

Nonlinear analysis and performance evaluation of the Annular Suspension and Pointing System (ASPS)

NASA Technical Reports Server (NTRS)

Joshi, S. M.

1978-01-01

The Annular Suspension and Pointing System (ASPS) can provide high accurate fine pointing for a variety of solar-, stellar-, and Earth-viewing scientific instruments during space shuttle orbital missions. In this report, a detailed nonlinear mathematical model is developed for the ASPS/Space Shuttle system. The equations are augmented with nonlinear models of components such as magnetic actuators and gimbal torquers. Control systems and payload attitude state estimators are designed in order to obtain satisfactory pointing performance, and statistical pointing performance is predicted in the presence of measurement noise and disturbances.

High density cell culture system

NASA Technical Reports Server (NTRS)

Spaulding, Glenn F. (Inventor)

1994-01-01

An annular culture vessel for growing mammalian cells is constructed in a one piece integral and annular configuration with an open end which is closed by an endcap. The culture vessel is rotatable about a horizontal axis by use of conventional roller systems commonly used in culture laboratories. The end wall of the endcap has tapered access ports to frictionally and sealingly receive the ends of hypodermic syringes. The syringes permit the introduction of fresh nutrient and withdrawal of spent nutrients. The walls are made of conventional polymeric cell culture material and are subjected to neutron bombardment to form minute gas permeable perforations in the walls.

Stability analysis of a liquid fuel annular combustion chamber. M.S. Thesis

NASA Technical Reports Server (NTRS)

Mcdonald, G. H.

1978-01-01

High frequency combustion instability problems in a liquid fuel annular combustion chamber are examined. A modified Galerkin method was used to produce a set of modal amplitude equations from the general nonlinear partial differential acoustic wave equation in order to analyze the problem of instability. From these modal amplitude equations, the two variable perturbation method was used to develop a set of approximate equations of a given order of magnitude. These equations were modeled to show the effects of velocity sensitive combustion instabilities by evaluating the effects of certain parameters in the given set of equations.

The effect of pulmonary hypertension on ovine tricuspid annular dynamics.

PubMed

Malinowski, Marcin; Wilton, Penny; Khaghani, Asghar; Langholz, David; Hooker, Victoria; Eberhart, Lenora; Hooker, Robert L; Timek, Tomasz A

2016-01-01

Pulmonary hypertension (PHT) is associated with tricuspid annular dilatation, but the effect of acute increase of pulmonary pressure on three-dimensional (3D) tricuspid annular dynamics and shape is unknown. Better understanding of tricuspid annular dynamics may lead to improved and more durable surgical reparative techniques. In nine open-chest anaesthetized sheep nine sonomicrometry crystals were implanted on the right ventricle while on cardiopulmonary bypass. Additional nine crystals were implanted around the tricuspid annulus (TA) with one crystal at each commissure defining three separate annular regions: anterior, posterior and septal. Two additional equidistant crystals were implanted between each commissure, creating three segments for every region. Pressure transducers were placed in the left ventricular (LV), right ventricular (RV) and right atrium. PHT was induced by acute pulmonary artery constriction with a pneumatic occluder. Sonomicrometry and echocardiographic data were collected before and after induction of PHT. TA area, regional and total perimeter, and 3D annular geometry were calculated from 3D crystal coordinates. Regional annular contraction was defined as the percentage difference between maximal and minimal region length during the cardiac cycle. PHT increased RV pressure from 31 ± 9 mmHg to 46 ± 13 mmHg (P = 0.001) and decreased left ventricular (LV) pressure from 111 ± 24 mmHg to 78 ± 36 mmHg (P = 0.018). There was no significant tricuspid regurgitation observed with PHT. During PHT, the TA area increased by 12 ± 13% from 641 ± 139 mm(2) to 721 ± 177 mm(2) (P = 0.037). The total perimeter increased from 103 ± 11 mm to 109 ± 13 mm (P = 0.02). All annular regions dilated significantly with PHT with 8 ± 10, 5 ± 5 and 5 ± 5% increase in anterior, posterior and septal annular length, respectively (P < 0.05). PHT reduced regional annular contraction in the anterior region only (17 ± 7 vs 14 ± 8%; P = 0.02). The TA had a complex 3D saddle geometry and the shape of the annulus was altered during PHT only in the antero-posterior region. The changes in tricuspid annular conformation, contractility and its 3D geometry observed during acute ovine PHT may help in the design of new pathology-specific tricuspid annular rings. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Calcification of the mitral valve and annulus: systematic evaluation of effects on valve anatomy and function.

PubMed

Movva, Rajesh; Murthy, Kinnari; Romero-Corral, Abel; Seetha Rammohan, Harish Raj; Fumo, Peter; Pressman, Gregg S

2013-10-01

Mitral annular calcification (MAC) is common in chronic kidney disease. It is associated with cardiovascular events and can cause valvular dysfunction, but it has not been systematically characterized. The aim of this prospective study was to assess the prevalence and distribution of MAC, its effects on leaflet motion, and its association with mitral stenosis and mitral regurgitation (MR) in a hemodialysis population. Echocardiograms were obtained in 75 consecutive hemodialysis outpatients. MAC extent and distribution were graded semiquantitatively using two-dimensional and three-dimensional echocardiography. Associations with the presence and severity of mitral stenosis and MR were explored. The mean age was 60 ± 14 years; 60% were men, and 87% were African American. MAC was present in 64% (moderate to severe in 48%). Calcium extended more than halfway onto the leaflet in 37% and beyond the annulus in 40%. Leaflet motion was restricted in 37%. Mitral stenosis was present in 28%, and the extent of calcification was associated with mean mitral valve gradient (P < .0001). MR was prevalent (present in 81%) but was severe in none. The severity of MAC was greater in patients with moderate MR than in those with no or mild MR (P = .04). Three-dimensional analysis suggested an uneven distribution of annular calcium; the middle and lateral anterior segments were less often calcified than the anterior-medial or posterior segments. Calcification in any annular segment was highly associated with restricted motion of the attached leaflet segment. MAC is common and often extensive in hemodialysis patients. Calcium may be unevenly distributed among the annular segments. When present, annular calcification reduces the angle of leaflet opening and can cause valvular dysfunction. Copyright © 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

Viscoelastic Relaxation of Topographic Highs on Venus to Produce Coronae

NASA Technical Reports Server (NTRS)

Janes, Daniel M.; Squyres, Steven W.

1995-01-01

Coronae on Venus are believed to result from the gravitationally driven relaxation of topography that was originally raised by mantle diapirs. We examine this relaxation using a viscoelastic finite element code, and show that an initially plateau shaped load will evolve to the characteristic corona topography of central raised bowl, annular rim, and surrounding moat. Stresses induced by the relaxation are consistent with the development of concentric extensional fracturing common on the outer margins of corona moats. However, relaxation is not expected to produce the concentric faulting often observed on the annular rim. The relaxation timescale is shorter than the diapir cooling timescale, so loss of thermal support controls the rate at which topography is reduced. The final corona shape is supported by buoyancy and flexural stresses and will persist through geologic time. Development of lower, flatter central bowls and narrower and more pronounced annular rims and moats enhanced by thicker crusts, higher thermal gradients, and crustal thinning over the diapir.

Force characteristic analysis of a magnetic gravity compensator with annular magnet array for magnetic levitation positioning system

NASA Astrophysics Data System (ADS)

Zhou, Yiheng; Kou, Baoquan; Liu, Peng; Zhang, He; Xing, Feng; Yang, Xiaobao

2018-05-01

Magnetic levitation positioning system (MLPS) is considered to be the state of the art in inspection and manufacturing systems in vacuum. In this paper, a magnetic gravity compensator with annular magnet array (AMA-MGC) for MLPS is proposed. Benefiting from the double-layer annular Halbach magnet array on the stator, the proposed AMA-MGC possesses the advantages of symmetrical force, high force density and small force fluctuation. Firstly, the basic structure and operation principle of the AMA-MGC are introduced. Secondly, the basic characteristics of the AMA-MGC such as magnetic field distribution, levitation force, parasitic force and parasitic torque are analyzed by the three-dimensional finite element analysis (3-D FEA). Thirdly, the influence of structural parameters on force density and force fluctuation is investigated, which is conductive to the design and optimization of the AMA-MGC. Finally, a prototype of the AMA-MGC is constructed, and the experiment shows good agreement with the 3-D FEA results.

Pulse-encoded ultrasound imaging of the vitreous with an annular array.

PubMed

Silverman, Ronald H; Ketterling, Jeffrey A; Mamou, Jonathan; Lloyd, Harriet O; Filoux, Erwan; Coleman, D Jackson

2012-01-01

The vitreous body is nearly transparent both optically and ultrasonically. Conventional 10- to 12-MHz diagnostic ultrasound can detect vitreous inhomogeneities at high gain settings, but has limited resolution and sensitivity, especially outside the fixed focal zone near the retina. To improve visualization of faint intravitreal fluid/gel interfaces, the authors fabricated a spherically curved 20-MHz five-element annular array ultrasound transducer, implemented a synthetic-focusing algorithm to extend the depth-of-field, and used a pulse-encoding strategy to increase sensitivity. The authors evaluated a human subject with a recent posterior vitreous detachment and compared the annular array with conventional 10-MHz ultrasound and spectral-domain optical coherence tomography. With synthetic focusing and chirp pulse-encoding, the array allowed visualization of the formed and fluid components of the vitreous with improved sensitivity and resolution compared with the conventional B-scan. Although optical coherence tomography allowed assessment of the posterior vitreoretinal interface, the ultrasound array allowed evaluation of the entire vitreous body. Copyright 2012, SLACK Incorporated.

Multiple discharge cylindrical pump collector

DOEpatents

Dunn, Charlton; Bremner, Robert J.; Meng, Sen Y.

1989-01-01

A space-saving discharge collector 40 for the rotary pump 28 of a pool-type nuclear reactor 10. An annular collector 50 is located radially outboard for an impeller 44. The annular collector 50 as a closed outer periphery 52 for collecting the fluid from the impeller 44 and producing a uniform circumferential flow of the fluid. Turning means comprising a plurality of individual passageways 54 are located in an axial position relative to the annular collector 50 for receiving the fluid from the annular collector 50 and turning it into a substantially axial direction.

Mechanically expandable annular seal

DOEpatents

Gilmore, R.F.

1983-07-19

A mechanically expandable annular reusable seal assembly to form an annular hermetic barrier between two stationary, parallel, and planar containment surfaces is described. A rotatable ring, attached to the first surface, has ring wedges resembling the saw-tooth array of a hole saw. Matching seal wedges are slidably attached to the ring wedges and have their motion restricted to be perpendicular to the second surface. Each seal wedge has a face parallel to the second surface. An annular elastomer seal has a central annular region attached to the seal wedges' parallel faces and has its inner and outer circumferences attached to the first surface. A rotation of the ring extends the elastomer seal's central region perpendicularly towards the second surface to create the fluid tight barrier. A counter rotation removes the barrier. 6 figs.

Link module for a downhole drilling network

DOEpatents

Hall, David R [Provo, UT; Fox, Joe [Provo, UT

2007-05-29

A repeater is disclosed in one embodiment of the present invention as including a cylindrical housing, characterized by a proximal end and a distal end, and having a substantially cylindrical wall, the cylindrical wall defining a central bore passing therethrough. The cylindrical housing is formed to define at least one recess in the cylindrical wall, into which a repeater is inserted. The cylindrical housing also includes an annular recess formed into at least one of the proximal end and the distal end. An annular transmission element, operably connected to the repeater, is located in the annular recess. In selected embodiments, the annular transmission element inductively converts electrical energy to magnetic energy. In other embodiments, the annular transmission element includes an electrical contact to transmit electrical energy directly to another contact.

Experimental verification of the flow characteristics of an active controlled microfluidic valve with annular boundary

NASA Astrophysics Data System (ADS)

Pan, Chun-Peng; Wang, Dai-Hua

2014-03-01

The principle and structural configuration of an active controlled microfluidic valve with annular boundary is presented in this paper. The active controlled flowrate model of the active controlled microfluidic valve with annular boundary is established. The prototypes of the active controlled microfluidic valves with annular boundaries with three different combinations of the inner and outer radii are fabricated and tested on the established experimental setup. The experimental results show that: (1) The active controlled microfluidic valve with annular boundary possesses the on/off switching and the continuous control capability of the fluid with simple structure and easy fabrication processing; (2) When the inner and outer diameters of the annular boundary are 1.5 mm and 3.5 mm, respectively, the maximum flowrate of the valve is 0.14 ml/s when the differential pressure of the inlet and outlet of the valve is 1000 Pa and the voltage applied to circular piezoelectric unimorph actuator is 100 V; (3) The established active controlled flowrate model can accurately predict the controlled flowrate of the active controlled microfluidic valves with the maximum relative error of 6.7%. The results presented in this paper lay the foundation for designing and developing the active controlled microfluidic valves with annular boundary driven by circular piezoelectric unimorph actuators.

Annular Mode Dynamics: Eddy Feedbacks and the Underlying Mechanisms

NASA Astrophysics Data System (ADS)

Hassanzadeh, P.; Ma, D.; Kuang, Z.

2017-12-01

Annular modes are the leading modes the extratropical circulation variability in both hemispheres on intraseasonal to interannual timescales. Temporal persistence and an equivalent-barotropic dipolar wind anomaly are the key spatio-temporal characteristics of the annular modes. The potential source(s) of this persistence, and in particular, whether there is a contribution from a positive eddy-jet feedback, are still unclear (e.g., Lorenz and Hartmann, 2001; Byrne et al., 2016). The mechanism of this feedback, and how it depends on processes such as surface friction, is also not well understood (e.g., Robinson, 2000; Gerber et al., 2007). In this study, we utilize the recently calculated Linear Response Function (LRF) of an idealized GCM (Hassanzadeh and Kuang, 2016). The LRF enables us to accurately calculate the response of eddy momentum/heat fluxes to the zonal-mean zonal wind and temperature anomalies of the annular mode. Using this information: 1) We confirm the existence of a positive eddy-jet feedback in the annular mode of the idealized GCM and accurately quantify the magnitude of this feedback; 2) We quantify the contribution of key processes (e.g., eddy momentum/heat fluxes and surface friction) to the annular mode dynamics in the idealized GCM. We show that as proposed by Robinson (2000), the baroclinic component of the annular mode and surface friction are essential for the positive eddy-jet feedback. Results show that this feedback increases the persistence of the annular mode by a factor of two. We also show that the barotropic component of the annular mode alone does not lead to persistence. In fact, the eddy-jet feedback for the barotropic component is negative because of the dominance of the barotropic governor effect. 3) Using the results of 1, we evaluate the underlying assumptions and accuracy of the statistical methods previously developed for quantifying the eddy-jet feedback (Lorenz and Hartmann, 2001; Simpson et al., 2013) and introduce a new statistical method that shows superior accuracy. We apply the new method to reanalysis data to quantify the eddy-jet feedback for the Southern Annular Mode. The key findings of 1-3 and their implications for our understanding of the annular mode dynamics will be discussed in this presentation.

Ultra-compact Marx-type high-voltage generator

DOEpatents

Goerz, David A.; Wilson, Michael J.

2000-01-01

An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allowing them to operate closer to their intrinsic breakdown levels; and uses manufacturing and assembly methods to integrate the capacitors and switches into stages that can be arranged into a low-profile Marx generator.

Spectroscopic study of the radionuclide 21Na for the astrophysical 17F(α ,p )20Ne reaction rate

NASA Astrophysics Data System (ADS)

Cha, S. M.; Chae, K. Y.; Ahn, S.; Bardayan, D. W.; Chipps, K. A.; Cizewski, J. A.; Howard, M. E.; Kozub, R. L.; Kwak, K.; Manning, B.; Matos, M.; O'Malley, P. D.; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Ratkiewicz, A.; Smith, M. S.; Strauss, S.

2017-08-01

The 24Mg(p ,α )21Na reaction was measured at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory to study the spectroscopy of the radionuclide 21Na. A 31-MeV proton beam from the 25 MV tandem accelerator bombarded isotopically enriched 24Mg targets. Recoiling 4He particles were identified by an annular silicon strip detector array. Two energy levels at Ex=6.594 and 7.132 MeV were observed for the first time. By comparing the experimentally obtained angular distributions and distorted wave Born approximation calculations, the spins and parities of 21Na energy levels were constrained. The astrophysically-important 17F(α ,p )20Ne reaction rate was also calculated for the first time using resonance parameters for 12 energy levels.

Cu(II) promotes amyloid pore formation

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

Zhang, Hangyu, E-mail: hangyuz@uw.edu; Rochet, Jean-Christophe; Stanciu, Lia A.

2015-08-14

The aggregation of α-synuclein is associated with dopamine neuron death in Parkinson's disease. There is controversy in the field over the question of which species of the aggregates, fibrils or protofibrils, are toxic. Moreover, compelling evidence suggested the exposure to heavy metals to be a risk of PD. Nevertheless, the mechanism of metal ions in promoting PD remains unclear. In this research, we investigated the structural basis of Cu(II) induced aggregation of α-synuclein. Using transmission electron microscopy experiments, Cu(II) was found to promote in vitro aggregation of α-synuclein by facilitating annular protofibril formation rather than fibril formation. Furthermore, neuroprotective baicalein disaggregatedmore » annular protofibrils accompanied by considerable decrease of β-sheet content. These results strongly support the hypothesis that annular protofibrils are the toxic species, rather than fibrils, thereby inspiring us to search novel therapeutic strategies for the suppression of the toxic annular protofibril formation. - Highlights: • Cu(II) promoted the annular protofibril formation of α-synuclein in vitro. • Cu(II) postponed the in vitro fibrillization of α-synuclein. • Neuroprotective baicalein disaggregated annular protofibrils.« less

Dissolver vessel bottom assembly

DOEpatents

Kilian, Douglas C.

1976-01-01

An improved bottom assembly is provided for a nuclear reactor fuel reprocessing dissolver vessel wherein fuel elements are dissolved as the initial step in recovering fissile material from spent fuel rods. A shock-absorbing crash plate with a convex upper surface is disposed at the bottom of the dissolver vessel so as to provide an annular space between the crash plate and the dissolver vessel wall. A sparging ring is disposed within the annular space to enable a fluid discharged from the sparging ring to agitate the solids which deposit on the bottom of the dissolver vessel and accumulate in the annular space. An inlet tangential to the annular space permits a fluid pumped into the annular space through the inlet to flush these solids from the dissolver vessel through tangential outlets oppositely facing the inlet. The sparging ring is protected against damage from the impact of fuel elements being charged to the dissolver vessel by making the crash plate of such a diameter that the width of the annular space between the crash plate and the vessel wall is less than the diameter of the fuel elements.

Micromachining Techniques in Developing High-Frequency Piezoelectric Composite Ultrasonic Array Transducers

PubMed Central

Liu, Changgeng; Djuth, Frank T.; Zhou, Qifa; Shung, K. Kirk

2014-01-01

Several micromachining techniques for the fabrication of high-frequency piezoelectric composite ultrasonic array transducers are described in this paper. A variety of different techniques are used in patterning the active piezoelectric material, attaching backing material to the transducer, and assembling an electronic interconnection board for transmission and reception from the array. To establish the feasibility of the process flow, a hybrid test ultrasound array transducer consisting of a 2-D array having an 8 × 8 element pattern and a 5-element annular array was designed, fabricated, and assessed. The arrays are designed for a center frequency of ~60 MHz. The 2-D array elements are 105 × 105 μm in size with 5-μm kerfs between elements. The annular array surrounds the square 2-D array and provides the option of transmitting from the annular array and receiving with the 2-D array. Each annular array element has an area of 0.71 mm2 with a 16-μm kerf between elements. The active piezoelectric material is (1 − x) Pb(Mg1/3Nb2/3)O3−xPbTiO3 (PMN-PT)/epoxy 1–3 composite with a PMN-PT pillar lateral dimension of 8 μm and an average gap width of ~4 μm, which was produced by deep reactive ion etching (DRIE) dry etching techniques. A novel electric interconnection strategy for high-density, small-size array elements was proposed. After assembly, the array transducer was tested and characterized. The capacitance, pulse–echo responses, and crosstalk were measured for each array element. The desired center frequency of ~60 MHz was achieved and the −6-dB bandwidth of the received signal was ~50%. At the center frequency, the crosstalk between adjacent 2-D array elements was about −33 dB. The techniques described herein can be used to build larger arrays containing smaller elements. PMID:24297027

Design and characteristic analysis of shaping optics for optical trepanning

NASA Astrophysics Data System (ADS)

Zeng, D.; Latham, W. P.; Kar, A.

2005-08-01

Optical trepanning is a new laser drilling method using an annular beam. The annular beams allow numerous irradiance profiles to supply laser energy to the workpiece and thus provide more flexibility in affecting the hole quality than a traditional circular laser beam. The refractive axicon system has been designed to generating a collimated annular beam. In this article, calculations of intensity distributions produced by this refractive system are made by evaluating the Kirchhoff-Fresnel diffraction. It is shown that the refractive system is able to transform a Gaussian beam into a full Gaussian annular beam. The base angle of the axicon lens, input laser beam diameter and intensity profiles are found to be important factors for the axcion refractive system. Their effects on the annular beam profiles are analyzed based on the numerical solutions of the diffraction patterns.

Gas turbine sealing apparatus

DOEpatents

Wiebe, David J; Wessell, Brian J; Ebert, Todd; Beeck, Alexander; Liang, George; Marussich, Walter H

2013-02-19

A gas turbine includes forward and aft rows of rotatable blades, a row of stationary vanes between the forward and aft rows of rotatable blades, an annular intermediate disc, and a seal housing apparatus. The forward and aft rows of rotatable blades are coupled to respective first and second portions of a disc/rotor assembly. The annular intermediate disc is coupled to the disc/rotor assembly so as to be rotatable with the disc/rotor assembly during operation of the gas turbine. The annular intermediate disc includes a forward side coupled to the first portion of the disc/rotor assembly and an aft side coupled to the second portion of the disc/rotor assembly. The seal housing apparatus is coupled to the annular intermediate disc so as to be rotatable with the annular intermediate disc and the disc/rotor assembly during operation of the gas turbine.

Freeze chromatography method and apparatus

DOEpatents

Scott, C.D.

1987-04-16

A freeze chromatography method and apparatus are provided which enable separation of the solutes contained in a sample. The apparatus includes an annular column construction comprising cylindrical inner and outer surfaces defining an annular passage therebetween. One of the surfaces is heated and the other cooled while passing an eluent through the annular passageway so that the eluent in contact with the cooled surface freezes and forms a frozen eluent layer thereon. A mixture of solutes dissolved in eluent is passed through the annular passageway in contact with the frozen layer so that the sample solutes in the mixture will tend to migrate either toward or away the frozen layer. The rate at which the mixture flows through the annular passageway is controlled so that the distribution of the sample solutes approaches that at equilibrium and thus a separation between the sample solutes occurs. 3 figs.

Evaluation of Argonne 9-cm and 10-cm Annular Centrifugal Contactors for SHINE Solution Processing

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

Wardle, Kent E.; Pereira, Candido; Vandegrift, George

2015-02-01

Work is in progress to evaluate the SHINE Medical Technologies process for producing Mo-99 for medical use from the fission of dissolved low-enriched uranium (LEU). This report addresses the use of Argonne annular centrifugal contactors for periodic treatment of the process solution. In a letter report from FY 2013, Pereira and Vandegrift compared the throughput and physical footprint for the two contactor options available from CINC Industries: the V-02 and V-05, which have rotor diameters of 5 cm and 12.7 cm, respectively. They suggested that an intermediately sized “Goldilocks” contactor might provide a better balance between throughput and footprint tomore » meet the processing needs for the uranium extraction (UREX) processing of the SHINE solution to remove undesired fission products. Included with the submission of this letter report are the assembly drawings for two Argonne-design contactors that are in this intermediate range—9-cm and 10-cm rotors, respectively. The 9-cm contactor (drawing number CE-D6973A, stamped February 15, 1978) was designed as a single-stage unit and built and tested in the late 1970s along with other size units, both smaller and larger. In subsequent years, a significant effort to developed annular centrifugal contactors was undertaken to support work at Hanford implementing the transuranic extraction (TRUEX) process. These contactors had a 10-cm rotor diameter and were fully designed as multistage units with four stages per assembly (drawing number CMT-E1104, stamped March 14, 1990). From a technology readiness perspective, these 10-cm units are much farther ahead in the design progression and, therefore, would require significantly less re-working to make them ready for UREX deployment. Additionally, the overall maximum throughput of ~12 L/min is similar to that of the 9-cm unit (10 L/min), and the former could be efficiently operated over much of the same range of throughput. As a result, only the 10-cm units are considered here, though drawings are provided for the 9-cm unit for reference.« less

Nonlinear distortion of thin liquid sheets

NASA Astrophysics Data System (ADS)

Mehring, Carsten Ralf

Thin planar, annular and conical liquid sheets or films are analyzed, in a unified manner, by means of a reduced- dimension approach providing governing equations for the nonlinear motion of planar and swirling annular thin inviscid and incompressible liquid sheets in zero gravity and with axial disturbances only. Temporal analyses of periodically disturbed infinite sheets are considered, as well as spatial analyses of semi-infinite sheets modulated at the nozzle exit. Results on planar and swirling annular or conical sheets are presented for a zero density ambient gas. Here, conical sheets are obtained in the nearfield of the nozzle exit by considering sheets or films with swirl in excess of that needed to stabilize the discharging stream in its annular configuration. For nonswirling annular sheets a spatially and/or temporally constant gas-core pressure is assumed. A model extension considering the influence of aerodynamic effects on planar sheets is proposed. For planar and annular sheets, linear analyses of the pure initial- and pure boundary-value problem provide insight into the propagation characteristics of dilational and sinuous waves, the (linear) coupling between both wave modes, the stability limits for the annular configuration, as well as the appearance of particular waves on semi-infinite modulated sheets downstream from the nozzle exit. Nonlinear steady-state solutions for the conical configuration (without modulation) are illustrated. Comparison between nonlinear and linear numerical and linear analytical solutions for temporally or spatially developing sheets provides detailed information on the nonlinear distortion characteristics including nonlinear wave propagation and mode-coupling for all the considered geometric configurations and for a variety of parameter configurations. Sensitivity studies on the influence of Weber number, modulation frequency, annular radius, forcing amplitude and sheet divergence on breakup or collapse length and times are reported for modulated semi-infinite annular and conical sheets. Comparisons between the different geometric configurations are made. For periodically disturbed planar sheets, accuracy of the employed reduced-dimension approach is demonstrated by comparison with more accurate two-dimensional vortex dynamics simulations.

AMTEC vapor-vapor series connected cells

NASA Technical Reports Server (NTRS)

Underwood, Mark L. (Inventor); Williams, Roger M. (Inventor); Ryan, Margaret A. (Inventor); Nakamura, Barbara J. (Inventor); Oconnor, Dennis E. (Inventor)

1995-01-01

An alkali metal thermoelectric converter (AMTEC) having a plurality of cells structurally connected in series to form a septum dividing a plenum into two chambers, and electrically connected in series, is provided with porous metal anodes and porous metal cathodes in the cells. The cells may be planar or annular, and in either case a metal alkali vapor at a high temperature is provided to the plenum through one chamber on one side of the wall and returned to a vapor boiler after condensation at a chamber on the other side of the wall in the plenum. If the cells are annular, a heating core may be placed along the axis of the stacked cells. This arrangement of series-connected cells allows efficient generation of power at high voltage and low current.

The Liquid Annular Reactor System (LARS) propulsion

NASA Technical Reports Server (NTRS)

Powell, James; Ludewig, Hans; Horn, Frederick; Lenard, Roger

1990-01-01

A concept for very high specific impulse (greater than 2000 seconds) direct nuclear propulsion is described. The concept, termed the liquid annular reactor system (LARS), uses liquid nuclear fuel elements to heat hydrogen propellant to very high temperatures (approximately 6000 K). Operating pressure is moderate (approximately 10 atm), with the result that the outlet hydrogen is virtually 100 percent dissociated to monatomic H. The molten fuel is contained in a solid container of its own material, which is rotated to stabilize the liquid layer by centripetal force. LARS reactor designs are described, together with neutronic and thermal-hydraulic analyses. Power levels are on the order of 200 megawatts. Typically, LARS designs use seven rotating fuel elements, are beryllium moderated, and have critical radii of approximately 100 cm (core L/D approximately equal to 1.5).

Glove port retrofit assembly and method of replacing components

DOEpatents

Giesen, Isaac M; Cournoyer, Michael E; Rael, David G

2014-11-18

What is disclosed is a system for retrofitting a sealed enclosure for performing work therein having an outer enclosure assembly configured to be clamped to the outer annular face of a port ring and form a sealed engagement with the outer annular surface of the port ring, a change assembly having an inner ring and an access element wherein the inner ring has a first annular cylinder body that is sized to be slidably received by the port ring and the access element is configured to be sealably and slidably positioned within the first annular cylinder body of the inner ring.

Thermal protection system and related methods

NASA Technical Reports Server (NTRS)

Garbe, Duane J. (Inventor)

2012-01-01

A thermal protection system and a method of manufacturing are disclosed. The thermal protection system may be configured to protect a movable joint, for example, a flexible bearing of a rocket motor nozzle. The thermal protection system includes a series of annular shims separated by a plurality of discrete spacers. Each shim of the series of annular shims may have a larger diameter than the previous shim, and the shims may nest. The shims may comprise a thermally stable material, and the discrete spacers may comprise an elastomer. Optionally, an annular bearing protector may separate the annular shims from the flexible bearing.

Stage 3 bucket shank bypass holes and related method

DOEpatents

Leone, Sal Albert; Eldrid, Sacheverel Quentin; Lupe, Douglas Arthur

2002-01-01

In a multi-stage turbine wherein at least one turbine wheel supports a row of buckets for rotation, and wherein the turbine wheel is located axially between first and second annular fixed arrays of nozzles, a cooling air circuit for purging a wheelspace between the turbine wheel and the second fixed annular array of nozzles comprising a flowpath through a shank portion of one or more buckets connecting a wheelspace between the turbine wheel and the first fixed annular array of nozzles with the wheelspace between the turbine wheel and the second fixed annular array of nozzles.

Visualizing the effect of dynamin inhibition on annular gap vesicle formation and fission

PubMed Central

Nickel, Beth; Boller, Marie; Schneider, Kimberly; Shakespeare, Teresa; Gay, Vernon; Murray, Sandra A.

2013-01-01

Summary Although gap junction plaque assembly has been extensively studied, mechanisms involved in plaque disassembly are not well understood. Disassembly involves an internalization process in which annular gap junction vesicles are formed. These vesicles undergo fission, but the molecular machinery needed for these fissions has not been described. The mechanoenzyme dynamin has been previously demonstrated to play a role in gap junction plaque internalization. To investigate the role of dynamin in annular gap junction vesicle fission, immunocytochemical, time-lapse and transmission electron microscopy were used to analyze SW-13 adrenocortical cells in culture. Dynamin was demonstrated to colocalize with gap junction plaques and vesicles. Dynamin inhibition, by siRNA knockdown or treatment with the dynamin GTPase inhibitor dynasore, increased the number and size of gap junction ‘buds’ suspended from the gap junction plaques. Buds, in control populations, were frequently released to form annular gap junction vesicles. In dynamin-inhibited populations, the buds were larger and infrequently released and thus fewer annular gap junction vesicles were formed. In addition, the number of annular gap junction vesicle fissions per hour was reduced in the dynamin-inhibited populations. We believe this to be the first report addressing the details of annular gap junction vesicle fissions and demonstrating a role of dynamin in this process. This information is crucial for elucidating the relationship between gap junctions, membrane regulation and cell behavior. PMID:23591819

Visualizing the effect of dynamin inhibition on annular gap vesicle formation and fission.

PubMed

Nickel, Beth; Boller, Marie; Schneider, Kimberly; Shakespeare, Teresa; Gay, Vernon; Murray, Sandra A

2013-06-15

Although gap junction plaque assembly has been extensively studied, mechanisms involved in plaque disassembly are not well understood. Disassembly involves an internalization process in which annular gap junction vesicles are formed. These vesicles undergo fission, but the molecular machinery needed for these fissions has not been described. The mechanoenzyme dynamin has been previously demonstrated to play a role in gap junction plaque internalization. To investigate the role of dynamin in annular gap junction vesicle fission, immunocytochemical, time-lapse and transmission electron microscopy were used to analyze SW-13 adrenocortical cells in culture. Dynamin was demonstrated to colocalize with gap junction plaques and vesicles. Dynamin inhibition, by siRNA knockdown or treatment with the dynamin GTPase inhibitor dynasore, increased the number and size of gap junction 'buds' suspended from the gap junction plaques. Buds, in control populations, were frequently released to form annular gap junction vesicles. In dynamin-inhibited populations, the buds were larger and infrequently released and thus fewer annular gap junction vesicles were formed. In addition, the number of annular gap junction vesicle fissions per hour was reduced in the dynamin-inhibited populations. We believe this to be the first report addressing the details of annular gap junction vesicle fissions and demonstrating a role of dynamin in this process. This information is crucial for elucidating the relationship between gap junctions, membrane regulation and cell behavior.

Female reproductive system morphology of crab-eating fox (Cerdocyon thous) and cryopreservation of genetic material for animal germplasm bank enrichment.

PubMed

Machado, L C; Roballo, K C S; Cury, F S; Ambrósio, C E

2017-12-01

The sprawl of the urbanization and road network process without building ecological corridors contributes to the high mortality rates and a threat to the population decline of wild species such as the crab-eating fox. A strategy for the ex situ conservation is the study of the reproductive biology of the species and cryopreservation of their genetic heritage through the formation of an animal germplasm bank. This research is in accordance with the principles adopted by Brazilian College of Animal Experimentation. Reproductive systems of Cerdocyon thous females (n = 7) were examined macroscopically and microscopically by histological techniques and scanning electron microscopy. Gross features showed the shape of the ovaries was similar to a bean, and the elongated oviducts lengths were between 5 and 8 cm, with body of the uterus (3 cm) with long and narrow uterine horns (9-11 cm). The cervix was as a single annular conformation carrying out communication between the uterus and the vagina. The vagina has lengthened and circular muscle and the vulva with dense anatomical conformation with a quite pronounced clitoris. In addition, with regard to the establishment of a cell line (fibroblasts) for the gene bank enrichment, cells showed a low clonogenic capacity, especially when compared to domestic dogs, which can be explained by "in vitro" environment, age and diet of the animal. However, it was possible to create a bank of limited cell number. This study had morphological and preservationist character and aimed to help at long term in the conservation of wild animal's genetic resources. © 2017 Blackwell Verlag GmbH.

High-angle annular dark field scanning transmission electron microscopy on carbon-based functional polymer systems.

PubMed

Sourty, Erwan; van Bavel, Svetlana; Lu, Kangbo; Guerra, Ralph; Bar, Georg; Loos, Joachim

2009-06-01

Two purely carbon-based functional polymer systems were investigated by bright-field conventional transmission electron microscopy (CTEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). For a carbon black (CB) filled polymer system, HAADF-STEM provides high contrast between the CB agglomerates and the polymer matrix so that details of the interface organization easily can be revealed and assignment of the CB phase is straightforward. For a second system, the functional polymer blend representing the photoactive layer of a polymer solar cell, details of its nanoscale organization could be observed that were not accessible with CTEM. By varying the camera length in HAADF-STEM imaging, the contrast can be enhanced between crystalline and amorphous compounds due to diffraction contrast so that nanoscale interconnections between domains are identified. In general, due to its incoherent imaging characteristics HAADF-STEM allows for reliable interpretation of the data obtained.

A Study Of High Speed Friction Behavior Under Elastic Loading Conditions

NASA Astrophysics Data System (ADS)

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

2005-03-01

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

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E.; Gonzalez, Manuel E.; Llewellyn, Brian C.; Bloys, James B.

2008-10-28

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E [Los Alamos, NM; Gonzalez, Manuel E [Kingwood, TX; Llewellyn, Brian C [Kingwood, TX; Bloys, James B [Katy, TX; Coates, Don M [Santa Fe, NM

2011-05-31

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E [Los Alamos, NM; Gonzalez, Manuel E [Kingwood, TX; Llewellyn, Brian C [Kingwood, TX; Bloys, James B [Katy, TX

2011-01-18

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E.; Gonzalez, Manuel E.; Llewellyn, Brian C.; Bloys, James B.

2010-06-29

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E [Los Alamos, NM; Gonzalez, Manuel E [Kingwood, NM; Llewellyn, Brian C [Kingwood, TX; Bloys, James B [Katy, TX; Coates, Don M [Santa Fe, NM

2011-06-21

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

You're Blocking the Light

ERIC Educational Resources Information Center

Riddle, Bob

2005-01-01

Eclipses typically occur in pairs twice each year, and the second pair for this year will be this month, starting with an annular solar eclipse on October 3, and two weeks later a partial lunar eclipse on October 17. The path of annularity will travel from the North Atlantic Ocean to Spain, where the annular phase will last for more than four…

An investigation of two phase flow pressure drops in a reduced acceleration environment

NASA Astrophysics Data System (ADS)

Wheeler, Montgomery W.; Best, Frederick R.; Reinarts, Thomas R.

1993-01-01

Thermal systems for space applications based on two phase flow have several advantages over single phase systems. Two phase thermal energy management and dynamic power conversion system advantages include the capability of achieving high specific power levels. Before two phase systems for space applications can be designed effectively, knowledge of the flow behavior in a reduced acceleration environment is necessary. To meet these needs, two phase flow experiments were conducted aboard the National Aeronautic and Space Administration's KC-135 using R12 as the working fluid. Annular flow two phase pressure drops were measured through 10.41-mm ID 1.251-m long glass tubing during periods with acceleration levels in the range ±0.05 G. The experiments were conducted with emphasis on achieving data with a high level of accuracy. The reduced acceleration annular flow pressure drops were compred with pressure drops measured in a 1-G environment for similar flow conditions. The reduced acceleration pressure drops were found to be 45% greater than the 1-G pressure drops. In addition, the reduced acceleration annular flow interfacial friction factors were compared with models for vertical up-flow in a 1-G environment. The reduced acceleration interfacial friction factor data was not predicted by the 1-G models.

Design of a portable noninvasive photoacoustic glucose monitoring system integrated laser diode excitation with annular array detection

NASA Astrophysics Data System (ADS)

Zeng, Lvming; Liu, Guodong; Yang, Diwu; Ren, Zhong; Huang, Zhen

2008-12-01

A near-infrared photoacoustic glucose monitoring system, which is integrated dual-wavelength pulsed laser diode excitation with eight-element planar annular array detection technique, is designed and fabricated during this study. It has the characteristics of nonivasive, inexpensive, portable, accurate location, and high signal-to-noise ratio. In the system, the exciting source is based on two laser diodes with wavelengths of 905 nm and 1550 nm, respectively, with optical pulse energy of 20 μJ and 6 μJ. The laser beam is optically focused and jointly projected to a confocal point with a diameter of 0.7 mm approximately. A 7.5 MHz 8-element annular array transducer with a hollow structure is machined to capture photoacoustic signal in backward mode. The captured signals excitated from blood glucose are processed with a synthetic focusing algorithm to obtain high signal-to-noise ratio and accurate location over a range of axial detection depth. The custom-made transducer with equal area elements is coaxially collimated with the laser source to improve the photoacoustic excite/receive efficiency. In the paper, we introduce the photoacoustic theory, receive/process technique, and design method of the portable noninvasive photoacoustic glucose monitoring system, which can potentially be developed as a powerful diagnosis and treatment tool for diabetes mellitus.

Design, construction and testing of annular diffusers for high speed civil transportation combustor applications

NASA Technical Reports Server (NTRS)

Okhio, Cyril B.

1995-01-01

A theoretical and an experimental design study of subsonic flow through curved-wall annular diffusers is being carried out in order to establish the most pertinent design parameters for such devices and the implications of their application in the design of engine components in the aerospace industries. This investigation consists of solving numerically the full Navier Stokes and Continuity equations for the time-mean flow. Various models of turbulence are being evaluated for adoption throughout the study and comparisons would be made with experimental data where they exist. Assessment of diffuser performance based on the dissipated mechanical energy would also be made. The experimental work involves the application of Computer Aided Design software tool to the development of a suitable annular diffuser geometry and the subsequent downloading of such data to a CNC machine at Central State University. The results of the investigations are expected to indicate that more cost effective component design of such devices as effective component design of such devices as diffusers which normally contain complex flows can still be achieved. In this regard a review paper was accepted and presented at the First International Conference on High Speed Civil Transportation Research held at North Carolina A&T in December of 1994.

High-frequency ultrasound annular array imaging. Part II: digital beamformer design and imaging.

PubMed

Hu, Chang-Hong; Snook, Kevin A; Cao, Pei-Jie; Shung, K Kirk

2006-02-01

This is the second part of a two-paper series reporting a recent effort in the development of a high-frequency annular array ultrasound imaging system. In this paper an imaging system composed of a six-element, 43 MHz annular array transducer, a six-channel analog front-end, a field programmable gate array (FPGA)-based beamformer, and a digital signal processor (DSP) microprocessor-based scan converter will be described. A computer is used as the interface for image display. The beamformer that applies delays to the echoes for each channel is implemented with the strategy of combining the coarse and fine delays. The coarse delays that are integer multiples of the clock periods are achieved by using a first-in-first-out (FIFO) structure, and the fine delays are obtained with a fractional delay (FD) filter. Using this principle, dynamic receiving focusing is achieved. The image from a wire phantom obtained with the imaging system was compared to that from a prototype ultrasonic backscatter microscope with a 45 MHz single-element transducer. The improved lateral resolution and depth of field from the wire phantom image were observed. Images from an excised rabbit eye sample also were obtained, and fine anatomical structures were discerned.

Eccentricity and misalignment effects on the performance of high-pressure annular seals

NASA Technical Reports Server (NTRS)

Chen, W. C.; Jackson, E. D.

1985-01-01

Annular pressure seals act as powerful hydrostatic bearings and influence the dynamic characteristics of rotating machinery. This work, using the existing concentric seal theories, provides a simple approximate method for calculation of both seal leakage and the dynamic coefficients for short seals with large eccentricity and/or misalignment of the shaft. Rotation and surface roughness effects are included for leakage and dynamic force calculation. The leakage calculations for both laminar and turbulent flow are compared with experimental results. The dynamic coefficients are compared with analytical results. Excellent agreement between the present work and published results have been observed up to the eccentricitiy ratio of 0.8.

Constructing a High Density Cell Culture System

NASA Technical Reports Server (NTRS)

Spaulding, Glenn F. (Inventor)

1996-01-01

An annular culture vessel for growing mammalian cells is constructed in a one piece integral and annular configuration with an open end which is closed by an endcap. The culture vessel is rotatable about a horizontal axis by use of conventional roller systems commonly used in culture laboratories. The end wall of the endcap has tapered access ports to frictionally and sealingly receive the ends of hypodermic syringes. The syringes permit the introduction of fresh nutrient and withdrawal of spent nutrients. The walls are made of conventional polymeric cell culture material and are subjected to neutron bombardment to form minute gas permeable perforations in the walls.

Transcatheter mitral direct annuloplasty: state of the art.

PubMed

Maisano, F; Kuck, K H

2014-06-01

Transcatheter mitral interventions are emerging as a novel therapy for patients with severe symptomatic mitral regurgitation who are deemed to be high risk or inoperable. Surgical treatment of mitral regurgitation includes a wide spectrum of therapies, ranging from leaflet and annular repair, to mitral valve replacement. Annuloplasty plays a fundamental role in open heart mitral valve repair, since it is associated with longer durability and higher degree of mitral regurgitation reduction. Direct annuloplasty is the interventional methodology most closely reproducing open heart annular repair. We describe the challenges and opportunities of the most promising technologies currently under development which will become available in clinical practice in the next future.

System for chemically digesting low level radioactive, solid waste material

DOEpatents

Cowan, Richard G.; Blasewitz, Albert G.

1982-01-01

An improved method and system for chemically digesting low level radioactive, solid waste material having a high through-put. The solid waste material is added to an annular vessel (10) substantially filled with concentrated sulfuric acid. Concentrated nitric acid or nitrogen dioxide is added to the sulfuric acid within the annular vessel while the sulfuric acid is reacting with the solid waste. The solid waste is mixed within the sulfuric acid so that the solid waste is substantilly fully immersed during the reaction. The off gas from the reaction and the products slurry residue is removed from the vessel during the reaction.

[Chronic recurrent annular neutrophilic dermatosis].

PubMed

Croci-Torti, A; Guillot, B; Rigau, V; Bessis, D

2017-05-01

Chronic recurrent annular neutrophilic dermatosis (CRAND) is a rare form of neutrophilic dermatosis characterised by chronic annular progression, histological impairment similar to that seen in Sweet's syndrome and the absence of association with generalised signs, abnormal laboratory values or underlying systemic disease. Herein we report two new cases. Case n o  1. A 41-year-old woman had presented with four annular lesions on the forearms and neckline which she had had for one year. Examination revealed a 5-cm annular lesion on the right forearm and four similar adjacent lesions. The condition spontaneously resolved after 4 weeks. Treatment with hydroxychloroquine 400mg per day for three months proved ineffective in preventing a further episode. However, following treatment with colchicine at a daily dose of 1mg for two months, no further relapses in the rash occurred over a 10-year observation period. Case n o  2. A 38-year-old woman consulted for recurrent annular erythema confined to the legs. Examination showed the presence of a red papular annular lesion on the right leg, encircling a yellowish macule with a central ring of fine scale; the lesion had been present for three weeks. Treatment with colchicine was initiated but the patient was lost to follow-up. In both cases, histological examination was evocative of Sweet's syndrome but no inflammatory or neutrophilic syndrome and no underlying systemic disease were demonstrated. CRAND presents as a stereotypical and benign form of neutrophilic dermatosis. A diagnosis of chronic recurrent annular dermatosis with gyrate progression should be considered in the absence of general signs, neutrophilia or underlying systemic disease. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Annular mode changes in the CMIP5 simulations

NASA Astrophysics Data System (ADS)

Gillett, N. P.; Fyfe, J. C.

2013-03-01

We investigate simulated changes in the annular modes in historical and RCP 4.5 scenario simulations of 37 models from the fifth Coupled Model Intercomparison Project (CMIP5), a much larger ensemble of models than has previously been used to investigate annular mode trends, with improved resolution and forcings. The CMIP5 models on average simulate increases in the Northern Annular Mode (NAM) and Southern Annular Mode (SAM) in every season by 2100, and no CMIP5 model simulates a significant decrease in either the NAM or SAM in any season. No significant increase in the NAM or North Atlantic Oscillation (NAO) is simulated in response to volcanic aerosol, and no significant NAM or NAO response to solar irradiance variations is simulated. The CMIP5 models simulate a significant negative SAM response to volcanic aerosol in MAM and JJA, and a significant positive SAM response to solar irradiance variations in MAM, JJA and DJF.

Nuclear reactor neutron shielding

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

Speaker, Daniel P; Neeley, Gary W; Inman, James B

A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactormore » cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.« less

Virtual cathode microwave generator having annular anode slit

DOEpatents

Kwan, Thomas J. T.; Snell, Charles M.

1988-01-01

A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.

Radiation Effects on the Thermodiffusive Instability of Premixed Flames on a Cylindrical Porous Flame Holder

NASA Astrophysics Data System (ADS)

Du, Minglong; Yang, Lijun

2017-10-01

A linear analysis method was used to investigate the mechanics of radiation heat loss and mass transfer in the porous wall of premixed annular flames and their effect on thermodiffusive instability. The dispersion relation between the disturbance wave growth rate and wavenumber was calculated numerically. Results showed that radiation heat loss elevated the annular flame slightly away from the porous wall. In the annular flame with small Lewis numbers, radiation heat loss changed the thermodiffusive instability from a pulsating to a cellular state, while for the large Lewis numbers, only the pulsating instability was represented. Increasing radiation heat loss and the radius of the porous wall enhanced the instability of the annular flames. Heat losses decreased with the continued increase in thickness of the porous wall and the decrease in porosity. Annular flames with long-wave mode along the angular direction were more unstable than the shortwave mode.

High-explosive driven crowbar switch

DOEpatents

Dike, Robert S.; Kewish, Jr., Ralph W.

1976-01-13

The disclosure relates to a compact explosive driven switch for use as a low resistance, low inductance crowbar switch. A high-explosive charge extrudes a deformable conductive metallic plate through a polyethylene insulating layer to achieve a hard current contact with a supportive annular conductor.

Loading Mode Optimization and Structure Tailoring in Spark Plasma Sintering of Monocarbide Powder-based Components for High Temperature Applications

NASA Astrophysics Data System (ADS)

Wei, Xialu

In this study, the spark plasma sintering (SPS) is employed to consolidate poorly sinter-able ultra-high temperature ceramic (UHTC) powders due to the fact that the conjoint application of electric current and mechanical pressure during SPS can largely offset the required processing temperature. Zirconium carbide (ZrC) is selected as target material as it broadly represents properties of typical UHTCs. Investigations on SPS of ZrC are concurrently conducted in two correlated regimes: One regime is used to optimize the SPS densification efficiency by manipulating the loading schematics. The other regime is used to produce complex shape carbide components for high temperature applications via SPS. Both theoretical and experimental studies are involved in the achievement of the formulated research objectives. Consolidation of ZrC has been carried out to form a densification map with determining the optimal processing parameters. The densification of ZrC is studied through the continuum theory of sintering, in which the ZrC power-law creep parameters have been determined through the clarification of electrical and thermal aspects of the employed SPS system. Then the SPS-forging setup is proposed as it is theoretically and experimentally proven to be able to render more densification than the regular SPS. SPS-forging and regular SPS are eventually integrated into a hybrid loading mode SPS regime to combine the advantages of the individual setups to obtain the optimal densification kinetics. Annular shape ZrC pellets have been fabricated using SPS. Finite element modeling framework is constructed to manifest the thermomechanical interactions during the SPS of annular shape ZrC specimens. The fabrication procedures are practically adapted to produce also annular shape carbide composites with excellent high temperature structural strength being used as alternative SPS tooling components. The applicability of annular shape fuel pellet to accommodate volume swelling under its service conditions is investigated. The irradiation-induced swelling phenomena are analyzed by analytical modeling and finite element simulations, in which the generated fission products are considered to be the sources of the fuel pellet swelling.

Annular-Cross-Section CFE Chamber

NASA Technical Reports Server (NTRS)

Sharnez, Rizwan; Sammons, David W.

1994-01-01

Proposed continuous-flow-electrophoresis (CFE) chamber of annular cross section offers advantages over conventional CFE chamber, and wedge-cross-section chamber described in "Increasing Sensitivity in Continuous-Flow Electrophoresis" (MFS-26176). In comparison with wedge-shaped chamber, chamber of annular cross section virtually eliminates such wall effects as electro-osmosis and transverse gradients of velocity. Sensitivity enhanced by incorporating gradient maker and radial (collateral) flow.

Supersonic coal water slurry fuel atomizer

DOEpatents

Becker, Frederick E.; Smolensky, Leo A.; Balsavich, John

1991-01-01

A supersonic coal water slurry atomizer utilizing supersonic gas velocities to atomize coal water slurry is provided wherein atomization occurs externally of the atomizer. The atomizer has a central tube defining a coal water slurry passageway surrounded by an annular sleeve defining an annular passageway for gas. A converging/diverging section is provided for accelerating gas in the annular passageway to supersonic velocities.

Characterization of annular two-phase gas-liquid flows in microgravity

NASA Technical Reports Server (NTRS)

Bousman, W. Scott; Mcquillen, John B.

1994-01-01

A series of two-phase gas-liquid flow experiments were developed to study annular flows in microgravity using the NASA Lewis Learjet. A test section was built to measure the liquid film thickness around the perimeter of the tube permitting the three dimensional nature of the gas-liquid interface to be observed. A second test section was used to measure the film thickness, pressure drop and wall shear stress in annular microgravity two-phase flows. Three liquids were studied to determine the effects of liquid viscosity and surface tension. The result of this study provide insight into the wave characteristics, pressure drop and droplet entrainment in microgravity annular flows.

Ultrasonographic assessment of the proximal digital annular ligament in the equine forelimb.

PubMed

Dik, K J; Boroffka, S; Stolk, P

1994-01-01

Ultrasonography was used with 6 normal cadaver forelimbs of Dutch Warmblood horses to delineate the ultrasonographic anatomy of the palmar pastern region, with emphasis on the proximal digital annular ligament. Using a 5.5 MHz sector scanner, the thin proximal digital annular ligament was not visible on offset sonograms. Only if the digital sheath in the normal limb was distended was the distal border of this ligament outlined. In all normal limbs the palmarodistal thickness of the combined skin-proximal digital annular ligament layer in the mid-pastern region was 2 mm. The flexor tendons and distal sesamoidean ligaments were easily identified as hyperechoic structures. Distension of the digital sheath in the normal limbs clearly outlined the anechoic digital sheath pouches. In 4 lame horses ultrasonography aided the diagnosis of functional proximal digital annular ligament constriction. In all 4 diseased forelimbs ultrasonography demonstrated thickening of the skin-proximal digital annular ligament layer and distension of the digital sheath. In one of these limbs the distended digital sheath was also thickened. The flexor tendons and distal sesamoidean ligaments were normal. There was no radiographic evidence of additional bone or joint lesions.

Thermal mechanical analysis of applications with internal heat generation

NASA Astrophysics Data System (ADS)

Govindarajan, Srisharan Garg

The radioactive tracer Technetium-99m is widely used in medical imaging and is derived from its parent isotope Molybedenum-99 (Mo-99) by radioactive decay. The majority of Molybdenum-99 (Mo-99) produced internationally is extracted from high enriched uranium (HEU) dispersion targets that have been irradiated. To alleviate proliferation risks associated with HEU-based targets, the use of non-HEU sources is being mandated. However, the conversion of HEU to LEU based dispersion targets affects the Mo-99 available for chemical extraction. A possible approach to increase the uranium density, to recover the loss in Mo-99 production-per-target, is to use an LEU metal foil placed within an aluminum cladding to form a composite structure. The target is expected to contain the fission products and to dissipate the generated heat to the reactor coolant. In the event of interfacial separation, an increase in the thermal resistance could lead to an unacceptable rise in the LEU temperature and stresses in the target. The target can be deemed structurally safe as long as the thermally induced stresses are within the yield strength of the cladding and welds. As with the thermal and structural safety of the annular target, the thermally induced deflection of the BORALRTM-based control blades, used by the University of Missouri Research Reactor (MURRRTM ), during reactor operation has been analyzed. The boron, which is the neutron absorber in BORAL, and aluminum mixture (BORAL meat) and the aluminum cladding are bonded together through powder metallurgy to establish an adherent bonded plate. As the BORAL absorbs both neutron particles and gamma rays, there is volumetric heat generation and a corresponding rise in temperature. Since the BORAL meat and aluminum cladding materials have different thermal expansion coefficients, the blade may have a tendency to deform as the blade temperature changes and the materials expand at different rates. In addition to the composite nature of the control blade, spatial variations in temperature within the control blade occur from the non-uniform heat generation within the BORAL as a result of the non-uniform thermal neutron flux along the longitudinal direction when the control blade is partially withdrawn. There is also variation in the heating profile through the thickness and about the circumferential width of the control blade. Mathematical curve-fits are generated for the non-uniform volumetric heat generation profile caused by the thermal neutron absorption and the functions are applied as heating conditions within a finite element model of the control blade built using the commercial finite element code Abaqus FEA. The finite element model is solved as a fully coupled thermal mechanical problem as in the case of the annular target. The resulting deflection is compared with the channel gap to determine if there is a significant risk of the control blade binding during reactor operation. Hence, this dissertation will consist of two sections. The first section will seek to present the thermal and structural safety analyses of the annular targets for the production of molybdenum-99. Since there hasn't been any detailed, documented, study on these annular targets in the past, the work complied in this dissertation will help to understand the thermal-mechanical behavior and failure margins of the target during in-vessel irradiation. As the work presented in this dissertation provides a general performance analysis envelope for the annular target, the tools developed in the process can also be used as useful references for future analyses that are specific to any reactor. The numerical analysis approach adopted and the analytical models developed, can also be applied to other applications, outside the Mo-99 project domain, where internal heat generation exists such as in electronic components and nuclear reactor control blades. The second section will focus on estimating the thermally induced deflection and hence establish operational safety of the BORAL control blades used at the Missouri University Research Reactor (MURR) to support their relicensing efforts with the Nuclear Regulatory Commission (NRC). The common theme in both these sections is the nuclear heat source, high heat flux, non-uniform heating, composite structures and differential thermal expansion. The goal is to establish the target and component operational safety, and also provide documented analysis that can be referred to in the future.

Probe with integrated heater and thermocouple pack

DOEpatents

McCulloch, Reg W.; Dial, Ralph E.; Finnell, Wilber K. R.

1990-01-01

A probe for measuring heat includes an elongate rod fitted within a sheath, and a plurality of annular recesses are formed on the surface of the rod in a spaced-apart relationship to form annular chambers that are resistant to heat flow. A longitudinal bore extends axially into the rod and within the cylinders defined by the annular chambers, and an integrated heater and thermocouple pack is dimensioned to fit within the bore. In construction, the integrated pack includes a plurality of wires disposed in electrical insulation within a sheath and a heater cable. These wires include one common wire and a plurality of thermocuple wires. The common wire is constructed of one type of conductive material while the thermocouple wires are each constructed of two types of materials so that at least one thermocouple junction is formed therein. All of the wires extend the length of the integrated pack and are connected together at their ends. The thermocouple wires are constructed to form thermocouple junctions proximate to each annular chamber for producing electromotive forces corresponding to the temperature of the rod within the annular chambers relative to outside the chambers. In the preferred embodiment, each thermocouple wire forms two thermocouple junctions, one junction being disposed within an annular chamber and the second junction being disposed outside of, but proximate to, the same annular chamber. In one embodiment two thermocouple wires are configured to double the sensitivity of the probe in one region.

Probe with integrated heater and thermocouple pack

DOEpatents

McCulloch, Reginald W.; Dial, Ralph E.; Finnell, Wilber K. R.

1988-01-01

A probe for measuring heat includes an elongate rod fitted within a sheath, and a plurality of annular recesses are formed on the surface of the rod in a spaced-apart relationship to form annular chambers that are resistant to heat flow. A longitudinal bore extends axially into the rod and within the cylinders defined by the annular chambers, and an integrated heater and thermocouple pack is dimensioned to fit within the bore. In construction, the integrated pack includes a plurality of wires disposed in electrical insulation within a sheath and a heater cable. These wires include one common wire and a plurality of thermocouple wires. The common wire is constructed of one type of conductive material while the thermocouple wires are each constructed of two types of materials so that at least one thermocouple junction is formed therein. All of the wires extend the length of the integrated pack and are connected together at their ends. The thermocouple wires are constructed to form thermocouple junctions proximate to each annular chamber for producing electromotive forces corresponding to the temperature of the rod within the annular chambers relative to outside the chambers. In the preferred embodiment, each thermocouple wire forms two thermocouple junctions, one junction being disposed within an annular chamber and the second junction being disposed outside of, but proximate to, the same annular chamber. In one embodiment two thermocouple wires are configured to double the sensitivity of the probe in one region.

Dual shell pressure balanced vessel

DOEpatents

Fassbender, Alexander G.

1992-01-01

A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

Effect of Spray Cone Angle on Flame Stability in an Annular Gas Turbine Combustor

NASA Astrophysics Data System (ADS)

Mishra, R. K.; Kumar, S. Kishore; Chandel, Sunil

2016-04-01

Effect of fuel spray cone angle in an aerogas turbine combustor has been studied using computational fluid dynamics (CFD) and full-scale combustor testing. For CFD analysis, a 22.5° sector of an annular combustor is modeled and the governing equations are solved using the eddy dissipation combustion model in ANSYS CFX computational package. The analysis has been carried out at 125 kPa and 303 K inlet conditions for spray cone angles from 60° to 140°. The lean blowout limits are established by studying the behavior of combustion zone during transient engine operation from an initial steady-state condition. The computational study has been followed by testing the practical full-scale annular combustor in an aerothermal test facility. The experimental result is in a good agreement with the computational predictions. The lean blowout fuel-air ratio increases as the spray cone angle is decreased at constant operating pressure and temperature. At higher spray cone angle, the flame and high-temperature zone moves upstream close to atomizer face and a uniform flame is sustained over a wide region causing better flame stability.

Wide acceptance angle, high concentration ratio, optical collector

NASA Technical Reports Server (NTRS)

Kruer, Mark A. (Inventor)

1991-01-01

A cassegrain optical system provides improved collection of off-axis light yet is still characterized by a high concentration ratio. The optical system includes a primary mirror for collecting incoming light and reflecting the light to a secondary mirror which, in turn, reflects the light to a solar cell or other radiation collection device. The primary mirror reflects incoming on-axis light onto an annular section of the secondary mirror and results in the reflection of a substantial amount of incoming off-axis light onto the remainder of the secondary mirror. Thus light which would otherwise be lost to the system will be captured by the collector. Furthermore, the off-axis sections of the secondary mirror may be of a different geometrical shape than the on-axis annular section so as to optimize the amount of off-axis light collected.

A Flexible Annular-Array Imaging Platform for Micro-Ultrasound

PubMed Central

Qiu, Weibao; Yu, Yanyan; Chabok, Hamid Reza; Liu, Cheng; Tsang, Fu Keung; Zhou, Qifa; Shung, K. Kirk; Zheng, Hairong; Sun, Lei

2013-01-01

Micro-ultrasound is an invaluable imaging tool for many clinical and preclinical applications requiring high resolution (approximately several tens of micrometers). Imaging systems for micro-ultrasound, including single-element imaging systems and linear-array imaging systems, have been developed extensively in recent years. Single-element systems are cheaper, but linear-array systems give much better image quality at a higher expense. Annular-array-based systems provide a third alternative, striking a balance between image quality and expense. This paper presents the development of a novel programmable and real-time annular-array imaging platform for micro-ultrasound. It supports multi-channel dynamic beamforming techniques for large-depth-of-field imaging. The major image processing algorithms were achieved by a novel field-programmable gate array technology for high speed and flexibility. Real-time imaging was achieved by fast processing algorithms and high-speed data transfer interface. The platform utilizes a printed circuit board scheme incorporating state-of-the-art electronics for compactness and cost effectiveness. Extensive tests including hardware, algorithms, wire phantom, and tissue mimicking phantom measurements were conducted to demonstrate good performance of the platform. The calculated contrast-to-noise ratio (CNR) of the tissue phantom measurements were higher than 1.2 in the range of 3.8 to 8.7 mm imaging depth. The platform supported more than 25 images per second for real-time image acquisition. The depth-of-field had about 2.5-fold improvement compared to single-element transducer imaging. PMID:23287923

Lens fiber organization in four avian species: a scanning electron microscopic study.

PubMed

Willekens, B; Vrensen, G

1985-01-01

The three-dimensional organization of the eye lenses of the chicken, the canary, the song-thrush and the kestrel was studied using light and scanning electron microscopy. The lenses of birds are characterized by the presence of two distinct compartments: the annular pad and the main lens body, separated by a cavum lenticuli. The annular pad fibers had a hexagonal circumference all contained a round nucleus and except for the canary were smooth-surfaced and lacking anchoring devices. In the canary, however, the annular pad fibers were studded with edge protrusions and ball-and-socket junctions. The semicircular main lens body fibers of all four species were studded with ball-and-socket junctions and edge protrusions. In contrast with mammals these anchoring devices were present throughout the lens up to the embryonal nucleus. Superficially the main lens body fibers were extremely flat. Additionally membrane elevations and depressions and globular elements were found on these central fibers in three species, the kestrel being the exception. At the transition between annular pad and main lens body the fibers turned their course and the nuclei became oval and disappeared in the deeper aspect of the main lens body. The cavum lenticuli was filled with globules tied off from the annular pad fibers. It seems attractive to assume that the presence of a separated annular pad, a cavum lenticuli filled with globular elements, the extreme flatness of the superficial central fibers and the studding of these central fibers with anchoring devices up to the embryonal nucleus are morphological expressions of the mouldability of the bird's eye lenses and consequently would explain their efficient accommodative mechanism including formation of a lenticonus. The presence of nuclei in the annular pad fibers and their typical change at the transitional zone between annular pad and main lens body are suggestive for a two-phased differentiation in bird's lens fibers: differentiation of the germinative epithelial cells to annular pad fibers which migrate to the main lens body after which they differentiate further to main lens body fibers.

Near-limit propagation of gaseous detonations in narrow annular channels

NASA Astrophysics Data System (ADS)

Gao, Y.; Ng, H. D.; Lee, J. H. S.

2017-03-01

New results on the near-limit behaviors of gaseous detonations in narrow annular channels are reported in this paper. Annular channels of widths 3.2 and 5.9 mm were made using circular inserts in a 50.8 mm-diameter external tube. The length of each annular channel was 1.8 m. Detonations were initiated in a steel driver tube where a small volume of a sensitive C2H2+ 2.5O2 mixture was injected to facilitate detonation initiation. A 2 m length of circular tube with a 50.8 mm diameter preceded the annular channel so that a steady Chapman-Jouguet (CJ) detonation was established prior to entering the annular channel. Four detonable mixtures of C2H2 {+} 2.5O2 {+} 85 % Ar, C2H2 {+} 2.5O2 {+} 70 % Ar, C3H8 {+} 5O2, and CH4 {+} 2O2 were used in the present study. Photodiodes spaced 10 cm throughout the length of both the annular channel and circular tube were used to measure the detonation velocity. In addition, smoked foils were inserted into the annular channel to monitor the cellular structure of the detonation wave. The results show that, well within the detonability limits, the detonation wave propagates along the channel with a small local velocity fluctuation and an average global velocity can be deduced. The average detonation velocity has a small deficit of 5-15 % far from the limits and the velocity rapidly decreases to 0.7V_{CJ}-0.8V_{CJ} when the detonation propagates near the limit. Subsequently, the fluctuation of local velocity also increases as the decreasing initial pressure approaches the limit. In the two annular channels used in this work, no galloping detonations were observed for both the stable and unstable mixtures tested. The present study also confirms that single-headed spinning detonation occurs at the limit, as in a circular tube, rather than the up and down "zig zag" mode in a two-dimensional, rectangular channel.

Axicon-based annular laser trap for studies on sperm activity

NASA Astrophysics Data System (ADS)

Shao, Bing; Vinson, Jaclyn M.; Botvinick, Elliot L.; Esener, Sadik C.; Berns, Michael W.

2005-08-01

As a powerful and noninvasive tool, laser trapping has been widely applied for the confinement and physiological study of biological cells and organelles. Researchers have used the single spot laser trap to hold individual sperm and quantitatively evaluated the motile force generated by a sperm. Early studies revealed the relationship between sperm motility and swimming behavior and helped the investigations in medical aspects of sperm activity. As sperm chemotaxis draws more and more interest in fertilization research, the studies on sperm-egg communication may help to explain male or female infertility and provide exciting new approaches to contraception. However, single spot laser trapping can only be used to investigate an individual target, which has limits in efficiency and throughput. To study the chemotactic response of sperm to eggs and to characterize sperm motility, an annular laser trap with a diameter of several hundred microns is designed, simulated with ray tracing tool, and implemented. An axicon transforms the wavefront such that the laser beam is incident on the microscope objective from all directions while filling the back aperture completely for high efficiency trapping. A trapping experiment with microspheres is carried out to evaluate the system performance. The power requirement for annular sperm trapping is determined experimentally and compared with theoretical calculations. With a chemo-attractant located in the center and sperm approaching from all directions, the annular laser trapping could serve as a speed bump for sperm so that motility characterization and fertility sorting can be performed efficiently.

Modifications to Marshall's Annular Seal Test (MAST) Rig and Facility for Improved Rotordynamic Coefficient Testing of Annular Seals and Fluid Film Bearings

NASA Technical Reports Server (NTRS)

Darden, J. M.; Earhart, E. M.

2011-01-01

The limits of rotordynamic stability continue to be pushed by the high power densities and rotational speeds of modern rocket engine turbomachinery. Destabilizing forces increase dramatically with rotor speed. Rotordynamic stability is lost when these destabilizing forces overwhelm the stabilizing forces. The vibration from the unstable rotor grows until it is limited by some nonlinearity. For example, a rolling element bearing with a stiffness characteristic that increases with deflection may limit the vibration amplitude. The loads and deflections resulting from this limit cycle vibration (LCV) can lead to bearing and seal damage which promotes ever increasing levels of subsynchronous vibration. Engineers combat LCV by introducing rotordynamic elements that generate increased stabilizing forces and reduced destabilizing forces. For example, replacing a labyrinth seal with a damping seal results in substantial increases in the damping and stiffness rotordynamic coefficients. Adding a swirl brake to the damping seal greatly reduces the destabilizing cross-coupled forces generated by the damping seal for even further increases in the stabilizing capacity. Marshall?s Annular Seal Test (MAST) rig is designed to experimentally measure the stabilizing capacity of new annular seal designs. The rig has been moved to a new facility and outfitted with a new slave bearing to allow increased test durations and to enable the testing of fluid film bearings. The purpose of this paper is to describe the new facility and the new bearing arrangement. Several novel seal and bearing designs will also be discussed.

Modeling of Focused Acoustic Field of a Concave Multi-annular Phased Array Using Spheroidal Beam Equation

NASA Astrophysics Data System (ADS)

Yu, Li-Li; Shou, Wen-De; Hui, Chun

2012-02-01

A theoretical model of focused acoustic field for a multi-annular phased array on concave spherical surface is proposed. In this model, the source boundary conditions of the spheroidal beam equation (SBE) for multi-annular phased elements are studied. Acoustic field calculated by the dynamic focusing model of SBE is compared with numerical results of the O'Neil and Khokhlov—Zabolotskaya—Kuznetsov (KZK) model, respectively. Axial dynamic focusing and the harmonic effects are presented. The results demonstrate that the dynamic focusing model of SBE is good valid for a concave multi-annular phased array with a large aperture angle in the linear or nonlinear field.

Compact Low Frequency Radio Antenna

DOEpatents

Punnoose, Ratish J.

2008-11-11

An antenna is disclosed that comprises a pair of conductive, orthogonal arches and a pair of conductive annular sector plates, wherein adjacent legs of each arch are fastened to one of the annular sector plates and the opposite adjacent pair of legs is fastened to the remaining annular sector plate. The entire antenna structure is spaced apart from a conductive ground plane by a thin dielectric medium. The antenna is driven by a feed conduit passing through the conductive ground plane and dielectric medium and attached to one of the annular sector plates, wherein the two orthogonal arched act as a pair of crossed dipole elements. This arrangement of elements provides a radiation pattern that is largely omni-directional above the horizon.

Ingestion resistant seal assembly

DOEpatents

Little, David A [Chuluota, FL

2011-12-13

A seal assembly limits gas leakage from a hot gas path to one or more disc cavities in a gas turbine engine. The seal assembly includes a seal apparatus associated with a blade structure including a row of airfoils. The seal apparatus includes an annular inner shroud associated with adjacent stationary components, a wing member, and a first wing flange. The wing member extends axially from the blade structure toward the annular inner shroud. The first wing flange extends radially outwardly from the wing member toward the annular inner shroud. A plurality of regions including one or more recirculation zones are defined between the blade structure and the annular inner shroud that recirculate working gas therein back toward the hot gas path.

On the Motion of an Annular Film in Microgravity Gas-Liquid Flow

NASA Technical Reports Server (NTRS)

McQuillen, John B.

2002-01-01

Three flow regimes have been identified for gas-liquid flow in a microgravity environment: Bubble, Slug, and Annular. For the slug and annular flow regimes, the behavior observed in vertical upflow in normal gravity is similar to microgravity flow with a thin, symmetrical annular film wetting the tube wall. However, the motion and behavior of this film is significantly different between the normal and low gravity cases. Specifically, the liquid film will slow and come to a stop during low frequency wave motion or slugging. In normal gravity vertical upflow, the film has been observed to slow, stop, and actually reverse direction until it meets the next slug or wave.

Annular beam with segmented phase gradients

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

Cheng, Shubo; Wu, Liang; Tao, Shaohua, E-mail: eshtao@csu.edu.cn

2016-08-15

An annular beam with a single uniform-intensity ring and multiple segments of phase gradients is proposed in this paper. Different from the conventional superposed vortices, such as the modulated optical vortices and the collinear superposition of multiple orbital angular momentum modes, the designed annular beam has a doughnut intensity distribution whose radius is independent of the phase distribution of the beam in the imaging plane. The phase distribution along the circumference of the doughnut beam can be segmented with different phase gradients. Similar to a vortex beam, the annular beam can also exert torques and rotate a trapped particle owingmore » to the orbital angular momentum of the beam. As the beam possesses different phase gradients, the rotation velocity of the trapped particle can be varied along the circumference. The simulation and experimental results show that an annular beam with three segments of different phase gradients can rotate particles with controlled velocities. The beam has potential applications in optical trapping and optical information processing.« less

Annular lichenoid dermatitis of youth ... and beyond: a series of 6 cases.

PubMed

Cesinaro, Anna Maria; Sighinolfi, Pamela; Greco, Antonietta; Garagnani, Lorella; Conti, Andrea; Fantini, Fabrizio

2009-05-01

Annular lichenoid dermatitis of youth (ALDY) is a clinico-pathologic entity described in children and young patients, clinically reminiscent of morphea, annular erythema, vitiligo or mycosis fungoides. We report on six patients presenting single or multiple lesions, distributed particularly on the flanks and abdomen, with clinical and histologic features consistent with ALDY. Two patients were young girls and four were adults males. Three patients received topical therapy and four showed complete resolution of the lesions after a 24-65 months follow-up. Analogously to the cases reported so far, immunohistochemistry showed a T cell infiltrate with a predominance of CD8+ lymphocytes, while T cell receptor rearrangement was absent in all cases. It seems appropriate to include annular lichenoid dermatitis of youth among the dermatoses with a lichenoid pattern. For the first time, we found that it can affect also adult patients, therefore we propose to rename the disease annular lichenoid dermatitis. The differential diagnosis with mycosis fungoides, especially in adult patients, is particularly crucial for their proper management and treatment.

Vacuum encapsulated hermetically sealed diamond amplified cathode capsule and method for making same

DOEpatents

Rao, Triveni; Walsh, John; Gangone, Elizabeth

2014-12-30

A vacuum encapsulated, hermetically sealed cathode capsule for generating an electron beam of secondary electrons, which generally includes a cathode element having a primary emission surface adapted to emit primary electrons, an annular insulating spacer, a diamond window element comprising a diamond material and having a secondary emission surface adapted to emit secondary electrons in response to primary electrons impinging on the diamond window element, a first cold-weld ring disposed between the cathode element and the annular insulating spacer and a second cold-weld ring disposed between the annular insulating spacer and the diamond window element. The cathode capsule is formed by a vacuum cold-weld process such that the first cold-weld ring forms a hermetical seal between the cathode element and the annular insulating spacer and the second cold-weld ring forms a hermetical seal between the annular spacer and the diamond window element whereby a vacuum encapsulated chamber is formed within the capsule.

Design of radial phononic crystal using annular soft material with low-frequency resonant elastic structures

NASA Astrophysics Data System (ADS)

Gao, Nansha; Wu, Jiu Hui; Yu, Lie; Xin, Hang

2016-10-01

Using FEM, we theoretically study the vibration properties of radial phononic crystal (RPC) with annular soft material. The band structures, transmission spectra, and displacement fields of eigenmode are given to estimate the starting and cut-off frequency of band gaps. Numerical calculation results show that RPC with annular soft material can yield low-frequency band gaps below 350 Hz. Annular soft material decreases equivalent stiffness of the whole structure effectively, and makes corresponding band gaps move to the lower frequency range. Physical mechanism behind band gaps is the coupling effect between long or traveling wave in plate matrix and the vibrations of corrugations. By changing geometrical dimensions of plate thickness e, the length of silicone rubber h2, and the corrugation width b, we can control the location and width of the first band gap. These research conclusions of RPC structure with annular soft material can potentially be applied to optimize band gaps, generate filters, and design acoustic devices.

Tunable high-q superconducting notch filter

DOEpatents

Pang, C.S.; Falco, C.M.; Kampwirth, R.T.; Schuller, I.K.

1979-11-29

A superconducting notch filter is made of three substrates disposed in a cryogenic environment. A superconducting material is disposed on one substrate in a pattern of a circle and an annular ring connected together. The second substrate has a corresponding pattern to form a parallel plate capacitor and the second substrate has the circle and annular ring connected by a superconducting spiral that forms an inductor. The third substrate has a superconducting spiral that is placed parallel to the first superconducting spiral to form a transformer. Relative motion of the first substrate with respect to the second is effected from outside the cryogenic environment to vary the capacitance and hence the frequency of the resonant circuit formed by the superconducting devices.

Piston manometer as an absolute standard for vacuum-gage calibration in the range 2 to 500 millitorr

NASA Technical Reports Server (NTRS)

Warshawsky, I.

1972-01-01

A thin disk is suspended, with very small annular clearance, in a cylindrical opening in the base plate of a calibration chamber. A continuous flow of calibration gas passes through the chamber and annular opening to a downstream high vacuum pump. The ratio of pressures on the two faces of the disk is very large, so that the upstream pressure is substantially equal to net force on the disk divided by disk area. This force is measured with a dynamometer that is calibrated in place with dead weights. A probable error of + or - (0.2 millitorr plus 0.2 percent) is attainable when downstream pressure is known to 10 percent.

Portable compton gamma-ray detection system

DOEpatents

Rowland, Mark S [Alamo, CA; Oldaker, Mark E [Pleasanton, CA

2008-03-04

A Compton scattered gamma-ray detector system. The system comprises a gamma-ray spectrometer and an annular array of individual scintillators. The scintillators are positioned so that they are arrayed around the gamma-ray spectrometer. The annular array of individual scintillators includes a first scintillator. A radiation shield is positioned around the first scintillator. A multi-channel analyzer is operatively connected to the gamma-ray spectrometer and the annular array of individual scintillators.

Annular gel reactor for chemical pattern formation

DOEpatents

Nosticzius, Zoltan; Horsthemke, Werner; McCormick, William D.; Swinney, Harry L.; Tam, Wing Y.

1990-01-01

The present invention is directed to an annular gel reactor suitable for the production and observation of spatiotemporal patterns created during a chemical reaction. The apparatus comprises a vessel having at least a first and second chamber separated one from the other by an annular polymer gel layer (or other fine porous medium) which is inert to the materials to be reacted but capable of allowing diffusion of the chemicals into it.

Elastic-plastic analysis of annular plate problems using NASTRAN

NASA Technical Reports Server (NTRS)

Chen, P. C. T.

1983-01-01

The plate elements of the NASTRAN code are used to analyze two annular plate problems loaded beyond the elastic limit. The first problem is an elastic-plastic annular plate loaded externally by two concentrated forces. The second problem is stressed radially by uniform internal pressure for which an exact analytical solution is available. A comparison of the two approaches together with an assessment of the NASTRAN code is given.

GAS BEARING

DOEpatents

Skarstrom, C.W.

1960-09-01

A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

The effect of acute mechanical left ventricular unloading on ovine tricuspid annular size and geometry.

PubMed

Malinowski, Marcin; Wilton, Penny; Khaghani, Asghar; Brown, Michael; Langholz, David; Hooker, Victoria; Eberhart, Lenora; Hooker, Robert L; Timek, Tomasz A

2016-09-01

Left ventricular assist device (LVAD) implantation may alter right ventricular shape and function and lead to tricuspid regurgitation. This in turn has been reported to be a determinant of right ventricular (RV) failure after LVAD implantation, but the effect of mechanical left ventricular (LV) unloading on the tricuspid annulus is unknown. The aim of the study was to provide insight into the effect of LVAD support on tricuspid annular geometry and dynamics that may help to optimize LV unloading with the least deleterious effect on the right-sided geometry. In seven open-chest anaesthetized sheep, nine sonomicrometry crystals were implanted on the right ventricle. Additional nine crystals were implanted around the tricuspid annulus, with one crystal at each commissure defining three separate annular regions: anterior, posterior and septal. Left ventricular unloading was achieved by connecting a cannula in the left atrium and the aorta to a continuous-flow pump. The pump was used for 15 min at a full flow of 3.8 ± 0.3 l/min. Epicardial echocardiography was used to assess the degree of tricuspid insufficiency. Haemodynamic, echocardiographic and sonomicrometry data were collected before and during full unloading. Tricuspid annular area, and the regional and total perimeter were calculated from crystal coordinates, while 3D annular geometry was expressed as the orthogonal distance of each annular crystal to the least squares plane of all annular crystals. There was no significant tricuspid regurgitation observed either before or during LV unloading. Right ventricular free wall to septum diameter increased significantly at end-diastole during unloading from 23.6 ± 5.8 to 26.3 ± 6.5 mm (P = 0.009), but the right ventricular volume, tricuspid annular area and total perimeter did not change from baseline. However, the septal part of the annulus significantly decreased its maximal length (38.6 ± 8.1 to 37.9 ± 8.2 mm, P = 0.03). Annular contraction was not altered. The tricuspid annulus had a complex 3D saddle-shaped geometry that was unaffected during experimental conditions. In healthy sheep hearts, left ventricular unloading increased septal-free wall RV diameter and reduced the length of the septal annulus, without altering the motion or geometry of the tricuspid annulus. Acute left ventricular unloading alone in healthy sheep was not sufficient to significantly perturb tricuspid annular dynamics and result in tricuspid insufficiency. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Quantitative Prediction of Paravalvular Leak in Transcatheter Aortic Valve Replacement Based on Tissue-Mimicking 3D Printing.

PubMed

Qian, Zhen; Wang, Kan; Liu, Shizhen; Zhou, Xiao; Rajagopal, Vivek; Meduri, Christopher; Kauten, James R; Chang, Yung-Hang; Wu, Changsheng; Zhang, Chuck; Wang, Ben; Vannan, Mani A

2017-07-01

This study aimed to develop a procedure simulation platform for in vitro transcatheter aortic valve replacement (TAVR) using patient-specific 3-dimensional (3D) printed tissue-mimicking phantoms. We investigated the feasibility of using these 3D printed phantoms to quantitatively predict the occurrence, severity, and location of any degree of post-TAVR paravalvular leaks (PVL). We have previously shown that metamaterial 3D printing technique can be used to create patient-specific phantoms that mimic the mechanical properties of biological tissue. This may have applications in procedural planning for cardiovascular interventions. This retrospective study looked at 18 patients who underwent TAVR. Patient-specific aortic root phantoms were created using the tissue-mimicking 3D printing technique using pre-TAVR computed tomography. The CoreValve (self-expanding valve) prostheses were deployed in the phantoms to simulate the TAVR procedure, from which post-TAVR aortic root strain was quantified in vitro. A novel index, the annular bulge index, was measured to assess the post-TAVR annular strain unevenness in the phantoms. We tested the comparative predictive value of the bulge index and other known predictors of post-TAVR PVL. The maximum annular bulge index was significantly different among patient subgroups that had no PVL, trace-to-mild PVL, and moderate-to-severe PVL (p = 0.001). Compared with other known PVL predictors, bulge index was the only significant predictor of moderate-severe PVL (area under the curve = 95%; p < 0.0001). Also, in 12 patients with post-TAVR PVL, the annular bulge index predicted the major PVL location in 9 patients (accuracy = 75%). In this proof-of-concept study, we have demonstrated the feasibility of using 3D printed tissue-mimicking phantoms to quantitatively assess the post-TAVR aortic root strain in vitro. A novel indicator of the post-TAVR annular strain unevenness, the annular bulge index, outperformed the other established variables and achieved a high level of accuracy in predicting post-TAVR PVL, in terms of its occurrence, severity, and location. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Characterization of interfacial waves in horizontal core-annular flow

NASA Astrophysics Data System (ADS)

Tripathi, Sumit; Bhattacharya, Amitabh; Singh, Ramesh; Tabor, Rico F.

2016-11-01

In this work, we characterize interfacial waves in horizontal core annular flow (CAF) of fuel-oil and water. Experimental studies on CAF were performed in an acrylic pipe of 15.5mm internal diameter, and the time evolution of the oil-water interface shape was recorded with a high speed camera for a range of different flow-rates of oil (Qo) and water (Qw). The power spectrum of the interface shape shows a range of notable features. First, there is negligible energy in wavenumbers larger than 2 π / a , where a is the thickness of the annulus. Second, for high Qo /Qw , there is no single dominant wavelength, as the flow in the confined annulus does not allow formation of a preferred mode. Third, for lower Qo /Qw , a dominant mode arises at a wavenumber of 2 π / a . We also observe that the power spectrum of the interface shape depends weakly on Qw, and strongly on Qo, perhaps because the net shear rate in the annulus appears to depend weakly on Qw as well. We also attempt to build a general empirical model for CAF by relating the interfacial stress (calculated via the mean pressure gradient) to the flow rate in the annulus, the annular thickness and the core velocity. Authors are thankful to Orica Mining Services (Australia) for the financial support.

The limit of the film extraction technique for annular two-phase flow in a small tube

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

Helm, D.E.; Lopez de Bertodano, M.; Beus, S.G.

1999-07-01

The limit of the liquid film extraction technique was identified in air-water and Freon-113 annular two-phase flow loops. The purpose of this research is to find the limit of the entrainment rate correlation obtained by Lopez de Bertodano et. al. (1998). The film extraction technique involves the suction of the liquid film through a porous tube and has been widely used to obtain annular flow entrainment and entrainment rate data. In these experiments there are two extraction probes. After the first extraction the entrained droplets in the gas core deposit on the tube wall. A new liquid film develops entirelymore » from liquid deposition and a second liquid film extraction is performed. While it is assumed that the entire liquid film is removed after the first extraction unit, this is not true for high liquid flow. At high liquid film flows the interfacial structure of the film becomes frothy. Then the entire liquid film cannot be removed at the first extraction unit, but continues on and is extracted at the second extraction unit. A simple model to characterize the limit of the extraction technique was obtained based on the hypothesis that the transition occurs due to a change in the wave structure. The resulting dimensionless correlation agrees with the data.« less

The limit of the film extraction technique for annular two-phase flow in a small tube

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

Helm, D.E.; Lopez de Bertodano, M.; Beus, S.G.

1999-07-01

The limit of the liquid film extraction technique was identified in air-water and Freon-113 annular two-phase flow loops. The purpose of this research is to find the limit of the entrainment rate correlation obtained by Lopez de Bertodano et al. (1998). The film extraction technique involves the suction of the liquid film through a porous tube and has been widely used to obtain annular flow entrainment and entrainment rate data. In the experiments there are two extraction probes. After the first extraction the entrained droplets in the gas core deposit on the tube wall. A new liquid film develops entirelymore » from liquid deposition and a second liquid film extraction is performed. While it is assumed that the entire liquid film is removed after the first extraction unit, this is not true for high liquid flow. At high liquid film flows the interfacial structure of the film becomes frothy. Then the entire liquid film cannot be removed at the first extraction unit, but continues on and is extracted at the second extraction unit. A simple model to characterize the limit of the extraction technique was obtained based on the hypothesis that the transition occurs due to a change in the wave structure. The resulting dimensionless correlation agrees with the data.« less

Solar Eclipses Observed from Antarctica

NASA Astrophysics Data System (ADS)

Pasachoff, Jay M.

2013-01-01

Aspects of the solar corona are still best observed during totality of solar eclipses, and other high-resolution observations of coronal active regions can be observed with radio telescopes by differentiation of occultation observations, as we did with the Jansky Very Large Array for the annular solar eclipse of 2012 May 20 in the US. Totality crossing Antarctica included the eclipse of 2003 November 23, and will next occur on 2021 December 4; annularity crossing Antarctica included the eclipse of 2008 February 7, and will next occur on 2014 April 29. Partial phases as high as 87% coverage were visible and were imaged in Antarctica on 2011 November 25, and in addition to partial phases of the total and annular eclipses listed above, partial phases were visible in Antarctica on 2001 July 2011, 2002 December 4, 2004 April 19, 2006 September 22, 2007 September 11, and 2009 January 26, and will be visible on 2015 September 13, 2016 September 1, 2017 February 26, 2018 February 15, and 2020 December 14. On behalf of the Working Group on Solar Eclipses of the IAU, the poster showed the solar eclipses visible from Antarctica and this article shows a subset (see www.eclipses.info for the full set). A variety of investigations of the Sun and of the response of the terrestrial atmosphere and ionosphere to the abrupt solar cutoff can be carried out at the future eclipses, making the Antarctic observations scientifically useful.

Manufacture of annular cermet articles

DOEpatents

Forsberg, Charles W.; Sikka, Vinod K.

2004-11-02

A method to produce annular-shaped, metal-clad cermet components directly produces the form and avoids multiple fabrication steps such as rolling and welding. The method includes the steps of: providing an annular hollow form with inner and outer side walls; filling the form with a particulate mixture of ceramic and metal; closing, evacuating, and hermetically sealing the form; heating the form to an appropriate temperature; and applying force to consolidate the particulate mixture into solid cermet.

Fuel assembly for the production of tritium in light water reactors

DOEpatents

Cawley, W.E.; Trapp, T.J.

1983-06-10

A nuclear fuel assembly is described for producing tritium in a light water moderated reactor. The assembly consists of two intermeshing arrays of subassemblies. The first subassemblies comprise concentric annular elements of an outer containment tube, an annular target element, an annular fuel element, and an inner neutron spectrums shifting rod. The second subassemblies comprise an outer containment tube and an inner rod of either fuel, target, or neutron spectrum shifting neutral.

Fuel assembly for the production of tritium in light water reactors

DOEpatents

Cawley, William E.; Trapp, Turner J.

1985-01-01

A nuclear fuel assembly is described for producing tritium in a light water moderated reactor. The assembly consists of two intermeshing arrays of subassemblies. The first subassemblies comprise concentric annular elements of an outer containment tube, an annular target element, an annular fuel element, and an inner neutron spectrums shifting rod. The second subassemblies comprise an outer containment tube and an inner rod of either fuel, target, or neutron spectrum shifting neutral.

An experimental technique for performing 3-D LDA measurements inside whirling annular seals

NASA Technical Reports Server (NTRS)

Morrison, Gerald L.; Johnson, Mark C.; Deotte, Robert E., Jr.; Thames, H. Davis, III.; Wiedner, Brian G.

1992-01-01

During the last several years, the Fluid Mechanics Division of the Turbomachinery Laboratory at Texas A&M University has developed a rather unique facility with the experimental capability for measuring the flow field inside journal bearings, labyrinth seals, and annular seals. The facility consists of a specially designed 3-D LDA system which is capable of measuring the instantaneous velocity vector within 0.2 mm of a wall while the laser beams are aligned almost perpendicular to the wall. This capability was required to measure the flow field inside journal bearings, labyrinth seals, and annular seals. A detailed description of this facility along with some representative results obtained for a whirling annular seal are presented.

Gas turbine combustor

NASA Technical Reports Server (NTRS)

Burd, Steven W. (Inventor); Cheung, Albert K. (Inventor); Dempsey, Dae K. (Inventor); Hoke, James B. (Inventor); Kramer, Stephen K. (Inventor); Ols, John T. (Inventor); Smith, Reid Dyer Curtis (Inventor); Sowa, William A. (Inventor)

2011-01-01

A gas turbine engine has a combustor module including an annular combustor having a liner assembly that defines an annular combustion chamber having a length, L. The liner assembly includes a radially inner liner, a radially outer liner that circumscribes the inner liner, and a bulkhead, having a height, H1, which extends between the respective forward ends of the inner liner and the outer liner. The combustor has an exit height, H3, at the respective aft ends of the inner liner and the outer liner interior. The annular combustor has a ratio H1/H3 having a value less than or equal to 1.7. The annular combustor may also have a ration L/H3 having a value less than or equal to 6.0.

Demagnetization of Nd 2Fe 14B, Pr 2Fe 14B, and Sm 2Co 17 Permanent Magnets in Spallation Irradiation Fields

DOE PAGES

Simos, Nikolaos; Ozaki, S.; Mokhov, N.; ...

2018-02-27

Prompted by the need for radiation-resistant permanent magnets for insertion devices (IDs) of high-brilliance next-generation synchrotrons such as the National Synchrotron Light Source II, the demagnetization of Nd 2Fe 14B and Pr 2Fe 14B was studied after exposure to a mixed irradiating field. Degradation and damage of the permanent magnetic material by components of electromagnetic showers induced in magnets by intense high-energy electron beams will alter the magnetic field structure of the IDs. Plate-like Nd 2Fe 14B magnets were irradiated to 1.8 Grad dose and were evaluated against Pr 2Fe 14B magnets irradiated to a lower dose of 20 Mrad.more » In addition, annular Sm 2Co 17 and Nd 2Fe 14B magnets integrated within a ferrofluidic feedthrough (FFFT) rotary seal were also irradiated to dose levels of 2 Grad for Sm 2Co 17 and 20 Mrad for Nd 2Fe 14B. Post-irradiation measurements of the magnetic intensity revealed that severe demagnetization exceeding 85% occurs in Nd 2Fe 14B magnets after only 50 Mrad dose and over 87% for Pr 2Fe 14B after 10 Mrad dose. The annular-shaped Sm 2Co 17 magnets of the FFFTs were almost insensitive to irradiation up to a dose of 2 Grad. Annular-shaped Nd 2Fe 14B magnets also showed resistance to demagnetization, a direct consequence of the annular shape which is characterized by the removal of the stronger demagnetizing field present at the center of a disk-like magnet. As a result, the sensitivity of boron-based permanent magnets to neutron energy (thermal versus fast) was also assessed via specifically designed experiments and discussed.« less

Demagnetization of Nd 2Fe 14B, Pr 2Fe 14B, and Sm 2Co 17 Permanent Magnets in Spallation Irradiation Fields

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

Simos, Nikolaos; Ozaki, S.; Mokhov, N.

Prompted by the need for radiation-resistant permanent magnets for insertion devices (IDs) of high-brilliance next-generation synchrotrons such as the National Synchrotron Light Source II, the demagnetization of Nd 2Fe 14B and Pr 2Fe 14B was studied after exposure to a mixed irradiating field. Degradation and damage of the permanent magnetic material by components of electromagnetic showers induced in magnets by intense high-energy electron beams will alter the magnetic field structure of the IDs. Plate-like Nd 2Fe 14B magnets were irradiated to 1.8 Grad dose and were evaluated against Pr 2Fe 14B magnets irradiated to a lower dose of 20 Mrad.more » In addition, annular Sm 2Co 17 and Nd 2Fe 14B magnets integrated within a ferrofluidic feedthrough (FFFT) rotary seal were also irradiated to dose levels of 2 Grad for Sm 2Co 17 and 20 Mrad for Nd 2Fe 14B. Post-irradiation measurements of the magnetic intensity revealed that severe demagnetization exceeding 85% occurs in Nd 2Fe 14B magnets after only 50 Mrad dose and over 87% for Pr 2Fe 14B after 10 Mrad dose. The annular-shaped Sm 2Co 17 magnets of the FFFTs were almost insensitive to irradiation up to a dose of 2 Grad. Annular-shaped Nd 2Fe 14B magnets also showed resistance to demagnetization, a direct consequence of the annular shape which is characterized by the removal of the stronger demagnetizing field present at the center of a disk-like magnet. As a result, the sensitivity of boron-based permanent magnets to neutron energy (thermal versus fast) was also assessed via specifically designed experiments and discussed.« less

Stable switching among high-order modes in polariton condensates

NASA Astrophysics Data System (ADS)

Sun, Yongbao; Yoon, Yoseob; Khan, Saeed; Ge, Li; Steger, Mark; Pfeiffer, Loren N.; West, Ken; Türeci, Hakan E.; Snoke, David W.; Nelson, Keith A.

2018-01-01

We report multistate optical switching among high-order bouncing-ball modes ("ripples") and whispering-gallery modes ("petals") of exciton-polariton condensates in a laser-generated annular trap. By tailoring the diameter and power of the annular trap, the polariton condensate can be switched among different trapped modes, accompanied by redistribution of spatial densities and superlinear increase in the emission intensities, implying that polariton condensates in this geometry could be exploited for an all-optical multistate switch. A model based on non-Hermitian modes of the generalized Gross-Pitaevskii equation reveals that this mode switching arises from competition between pump-induced gain and in-plane polariton loss. The parameters for reproducible switching among trapped modes have been measured experimentally, giving us a phase diagram for mode switching. Taken together, the experimental result and theoretical modeling advance our fundamental understanding of the spontaneous emergence of coherence and move us toward its practical exploitation.

A generalized theory for eccentric and misalignment effects in high-pressure annular seals

NASA Technical Reports Server (NTRS)

Chen, W. C.; Jackson, E. D.

1986-01-01

High-pressure annular seal leakage and dynamic coefficients vary with eccentricity and misalignment. Recent seal leakage data with both concentric and fully eccentric alignments support the seal leakage model with surface roughness and eccentricity effects included. In this paper, the seal dynamic coefficient calculation has been generalized and allows direct calculation of the seal dynamic coefficients at any circumferential location. The generalized solution agrees with the results obtained by using the calculated values of an earlier paper and performing a coordinate transformation. The analysis results coincide with the measured data in showing that the stiffness and damping matrices of seal coefficients are not skew symmetric, and the main diagonal seal coefficients are not equal. The measured direct stiffnesses were found higher than predicted by the concentric seal theory, but this may be explained by the presence of eccentricity in the test operating mode.

Study of the interfacial reactions between a bioactive apatite-mullite glass-ceramic coating and titanium substrates using high angle annular dark field transmission electron microscopy.

PubMed

Stanton, Kenneth T; O'Flynn, Kevin P; Nakahara, Shohei; Vanhumbeeck, Jean-François; Delucca, John M; Hooghan, Bobby

2009-04-01

Glass of generic composition SiO(2) . Al(2)O(3) . P(2)O(5) . CaO . CaF(2) will crystallise predominantly to apatite and mullite upon heat-treatment. Such ceramics are bioactive, osseoconductive, and have a high resistance to fracture. As a result, they are under investigation for use as biomedical device coatings, and in particular for orthopaedic implants. Previous work has shown that the material can be successfully enamelled to titanium with an interfacial reaction zone produced during heat treatment. The present study uses high angle annular dark field transmission electron microscopy (HAADF-TEM) to conduct a detailed examination of this region. Results show evidence of complex interfacial reactions following the diffusion of titanium into an intermediate layer and the production of titanium silicides and titanium phosphides. These results confirm previously hypothesised mechanisms for the bonding of silicate bioceramics with titanium alloys.

Quantitative composition determination at the atomic level using model-based high-angle annular dark field scanning transmission electron microscopy.

PubMed

Martinez, G T; Rosenauer, A; De Backer, A; Verbeeck, J; Van Aert, S

2014-02-01

High angle annular dark field scanning transmission electron microscopy (HAADF STEM) images provide sample information which is sensitive to the chemical composition. The image intensities indeed scale with the mean atomic number Z. To some extent, chemically different atomic column types can therefore be visually distinguished. However, in order to quantify the atomic column composition with high accuracy and precision, model-based methods are necessary. Therefore, an empirical incoherent parametric imaging model can be used of which the unknown parameters are determined using statistical parameter estimation theory (Van Aert et al., 2009, [1]). In this paper, it will be shown how this method can be combined with frozen lattice multislice simulations in order to evolve from a relative toward an absolute quantification of the composition of single atomic columns with mixed atom types. Furthermore, the validity of the model assumptions are explored and discussed. © 2013 Published by Elsevier B.V. All rights reserved.

Column ratio mapping: a processing technique for atomic resolution high-angle annular dark-field (HAADF) images.

PubMed

Robb, Paul D; Craven, Alan J

2008-12-01

An image processing technique is presented for atomic resolution high-angle annular dark-field (HAADF) images that have been acquired using scanning transmission electron microscopy (STEM). This technique is termed column ratio mapping and involves the automated process of measuring atomic column intensity ratios in high-resolution HAADF images. This technique was developed to provide a fuller analysis of HAADF images than the usual method of drawing single intensity line profiles across a few areas of interest. For instance, column ratio mapping reveals the compositional distribution across the whole HAADF image and allows a statistical analysis and an estimation of errors. This has proven to be a very valuable technique as it can provide a more detailed assessment of the sharpness of interfacial structures from HAADF images. The technique of column ratio mapping is described in terms of a [110]-oriented zinc-blende structured AlAs/GaAs superlattice using the 1 angstroms-scale resolution capability of the aberration-corrected SuperSTEM 1 instrument.

Analytical evaluation of the impact of broad specification fuels on high bypass turbofan engine combustors

NASA Technical Reports Server (NTRS)

Taylor, J. R.

1979-01-01

Six conceptual combustor designs for the CF6-50 high bypass turbofan engine and six conceptual combustor designs for the NASA/GE E3 high bypass turbofan engine were analyzed to provide an assessment of the major problems anticipated in using broad specification fuels in these aircraft engine combustion systems. Each of the conceptual combustor designs, which are representative of both state-of-the-art and advanced state-of-the-art combustion systems, was analyzed to estimate combustor performance, durability, and pollutant emissions when using commercial Jet A aviation fuel and when using experimental referee board specification fuel. Results indicate that lean burning, low emissions double annular combustor concepts can accommodate a wide range of fuel properties without a serious deterioration of performance or durability. However, rich burning, single annular concepts would be less tolerant to a relaxation of fuel properties. As the fuel specifications are relaxed, autoignition delay time becomes much smaller which presents a serious design and development problem for premixing-prevaporizing combustion system concepts.

Complete annular and partial oblique pulley release for pediatric locked trigger thumb

PubMed Central

Kuo, Meiying

2010-01-01

Purpose To report the surgical treatment outcome of pediatric locked trigger thumb by sequential release of the annular pulley and partial release of the oblique pulley. Materials and Methods A retrospective review was undertaken on 28 operative thumbs in 24 patients with an average follow-up of 79 months. Intraoperative observations focused on the pathology of the pulley system. Surgical technique involved complete release of the annular pulley, which alone was insufficient in relieving the deformity, along with release of the proximal 50% of the oblique pulley in all patients. Postoperative parameters of bowstringing, resolution of Notta's node, thumb interphalangeal motion, and patient/parent satisfaction were assessed. Results The oblique pulley appeared stenotic, whereas the annular pulley was observed to be membranous and nearly indistinguishable from the tendon sheath. No patients had recurrence of thumb locking or triggering. No bowstringing was detected, and Notta’s node resolved fully in 19 of 20 thumbs. Five thumbs had an average of 12o less active IP joint motion without flexion contracture (i.e., less flexion). All patients or families expressed overall satisfaction with the procedure. Conclusion The annular pulley was attenuated in the majority of cases and the proximal half of the oblique pulley was stenotic in all patients. Releasing 50% of the oblique pulley after complete annular pulley release was necessary in all thumbs to achieve full FPL excursion. Mistaking the constricted proximal oblique pulley for an annular pulley may encourage releasing the entire oblique pulley, leading to an adverse result. Satisfactory outcome was achieved after surgical treatment of pediatric locked trigger thumbs. Type of Study/Level of Evidence Therapeutic IV. PMID:22131924

Electron microscope aperture system

NASA Technical Reports Server (NTRS)

Heinemann, K. (Inventor)

1976-01-01

An electron microscope including an electron source, a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen, and an objective lens having an annular objective aperture, for focusing electrons passing through the specimen onto an image plane are described. The invention also entails a method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques.

Low NO.sub.x combustor

DOEpatents

Taylor, Jack R.

1987-01-01

A combustor having an annular first stage, a generally cylindrically-shaped second stage, and an annular conduit communicably connecting the first and second stages. The conduit has a relatively small annular height and a large number of quench holes in the walls thereof such that quench air injected into the conduit through the quench holes will mix rapidly with, or quench, the combustion gases flowing through the conduit. The rapid quenching reduces the amount of NO.sub.x produced in the combustor.

Annular dynamics of memo3D annuloplasty ring evaluated by 3D transesophageal echocardiography.

PubMed

Nishi, Hiroyuki; Toda, Koichi; Miyagawa, Shigeru; Yoshikawa, Yasushi; Fukushima, Satsuki; Yoshioka, Daisuke; Sawa, Yoshiki

2018-04-01

We assessed the mitral annular motion after mitral valve repair with the Sorin Memo 3D® (Sorin Group Italia S.r.L., Saluggia, Italy), which is a unique complete semirigid annuloplasty ring intended to restore the systolic profile of the mitral annulus while adapting to the physiologic dynamism of the annulus, using transesophageal real-time three-dimensional echocardiography. 17 patients (12 male; mean age 60.4 ± 14.9 years) who underwent mitral annuloplasty using the Memo 3D ring were investigated. Mitral annular motion was assessed using QLAB®version8 allowing for a full evaluation of the mitral annulus dynamics. The mitral annular dimensions were measured throughout the cardiac cycle using 4D MV assessment2® while saddle shape was assessed through sequential measurements by RealView®. Saddle shape configuration of the mitral annulus and posterior and anterior leaflet motion could be observed during systole and diastole. The mitral annular area changed during the cardiac cycle by 5.7 ± 1.8%.The circumference length and diameter also changed throughout the cardiac cycle. The annular height was significantly higher in mid-systole than in mid-diastole (p < 0.05). The Memo 3D ring maintained a physiological saddle-shape configuration throughout the cardiac cycle. Real-time three-dimensional echocardiography analysis confirmed the motion and flexibility of the Memo 3D ring upon implantation.

Geometrically nonlinear resonance of higher-order shear deformable functionally graded carbon-nanotube-reinforced composite annular sector plates excited by harmonic transverse loading

NASA Astrophysics Data System (ADS)

Gholami, Raheb; Ansari, Reza

2018-02-01

This article presents an attempt to study the nonlinear resonance of functionally graded carbon-nanotube-reinforced composite (FG-CNTRC) annular sector plates excited by a uniformly distributed harmonic transverse load. To this purpose, first, the extended rule of mixture including the efficiency parameters is employed to approximately obtain the effective material properties of FG-CNTRC annular sector plates. Then, the focus is on presenting the weak form of discretized mathematical formulation of governing equations based on the variational differential quadrature (VDQ) method and Hamilton's principle. The geometric nonlinearity and shear deformation effects are considered based on the von Kármán assumptions and Reddy's third-order shear deformation plate theory, respectively. The discretization process is performed via the generalized differential quadrature (GDQ) method together with numerical differential and integral operators. Then, an efficient multi-step numerical scheme is used to obtain the nonlinear dynamic behavior of the FG-CNTRC annular sector plates near their primary resonance as the frequency-response curve. The accuracy of the present results is first verified and then a parametric study is presented to show the impacts of CNT volume fraction, CNT distribution pattern, geometry of annular sector plate and sector angle on the nonlinear frequency-response curve of FG-CNTRC annular sector plates with different edge supports.

Radical antegrade modular pancreatosplenectomy for adenocarcinomaof the body of the pancreas in a patient with portal annular pancreas, aberrant hepatic artery, and absence of the celiac trunk: A case report.

PubMed

Yuan, Hao; Wu, Pengfei; Chen, Jianmin; Lu, Zipeng; Chen, Lei; Wei, Jishu; Guo, Feng; Cai, Baobao; Yin, Jie; Xu, Dong; Jiang, Kuirong; Miao, Yi

2017-12-01

Portal annular pancreas is a rare anatomic variation, where the uncinated process of the pancreas connects with the dorsal pancreas and the pancreas tissue encases the portal vein (PV), superior mesenteric vein (SMV) or splenic vein (SV). Malignancies are quite uncommon in the patients, who have an annular pancreas especially portal annular pancreas. Ectopic common hepatic artery and absence of the celiac trunk (CT) are the other infrequent abnormalities. A 74-year-old man suffered from upper abdominal and back pain. Contrast enhanced computed tomography indicated a low-density mass in the body of the pancreas. Pathological report showed adenocarcinoma of the body of pancreas after radical antegrade modular pancreatosplenectomy (RAMPS). In the operation, we found the superior vein and portal vein was surrounded by the pancreatic tissue. The left gastric artery and splenic artery originated respectively from abdominal aorta, and celiac trunk was not viewed. In addition, the common hepatic artery was a branch from the superior mesenteric artery. In general, this is a novel clinical case of pancreatic carcinoma happening in the portal annular pancreas which was accompanied with aberrant hepatic artery and absence of the celiac trunk at the same time. Confronted with the pancreatic neoplasms, the possibility of coexistent annular pancreas and arterial variations should be considered.

A thickness-mode piezoelectric micromachined ultrasound transducer annular array using a PMN–PZT single crystal

NASA Astrophysics Data System (ADS)

Kang, Woojin; Jung, Joontaek; Lee, Wonjun; Ryu, Jungho; Choi, Hongsoo

2018-07-01

Micro-electromechanical system (MEMS) technologies were used to develop a thickness-mode piezoelectric micromachined ultrasonic transducer (Tm-pMUT) annular array utilizing a lead magnesium niobate–lead zirconate titanate (PMN–PZT) single crystal prepared by the solid-state single-crystal-growth method. Dicing is a conventional processing method for PMN–PZT single crystals, but MEMS technology can be adopted for the development of Tm-pMUT annular arrays and has various advantages, including fabrication reliability, repeatability, and a curved element shape. An inductively coupled plasma–reactive ion etching process was used to etch a brittle PMN–PZT single crystal selectively. Using this process, eight ring-shaped elements were realized in an area of 1  ×  1 cm2. The resonance frequency and effective electromechanical coupling coefficient of the Tm-pMUT annular array were 2.66 (±0.04) MHz, 3.18 (±0.03) MHz, and 30.05%, respectively, in the air. The maximum positive acoustic pressure in water, measured at a distance of 7.27 mm, was 40 kPa from the Tm-pMUT annular array driven by a 10 Vpp sine wave at 2.66 MHz without beamforming. The proposed Tm-pMUT annular array using a PMN–PZT single crystal has the potential for various applications, such as a fingerprint sensor, and for ultrasonic cell stimulation and low-intensity tissue stimulation.

Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

NASA Astrophysics Data System (ADS)

Teng, Yan; Sun, Jun; Chen, Changhua; Shao, Hao

2013-07-01

This paper presents an approach that greatly enhances both the output power and the conversion efficiency of the coaxial relativistic backward wave oscillator (CRBWO) by using coaxial dual annular cathodes, which increases the diode current rather than the diode voltage. The reasons for the maladjustment of CRBWO under a high diode voltage are analyzed theoretically. It is found that by optimization of the diode structure, the shielding effect of the space charge of the outer beams on the inner cathode can be alleviated effectively and dual annular beams with the same kinetic energy can be explosively emitted in parallel. The coaxial reflector can enhance the conversion efficiency by improving the premodulation of the beams. The electron dump on the inner conductor ensures that the electron beams continue to provide kinetic energy to the microwave output until they vanish. Particle-in-cell (PIC) simulation results show that generation can be enhanced up to an output power level of 3.63 GW and conversion efficiency of 45% at 8.97 GHz under a diode voltage of 659 kV and current of 12.27 kA. The conversion efficiency remains above 40% and the output frequency variation is less than 100 MHz over a voltage range of more than 150 kV. Also, the application of the coaxial dual annular cathodes means that the diode impedance is matched to that of the transmission line of the accelerators. This impedance matching can effectively eliminate power reflection at the diode, and thus increase the energy efficiency of the entire system.

Continued Investigation of Leakage and Power Loss Test Results for Competing Turbine Engine Seals

NASA Technical Reports Server (NTRS)

Delgado, Irebert R.; Proctor, Margaret P.

2006-01-01

Secondary seal leakage in jet engine applications results in power losses to the engine cycle. Likewise, seal power loss in jet engines not only result in efficiency loss but also increase the heat input into the engine resulting in reduced component lives. Experimental work on labyrinth and annular seals was performed at NASA Glenn Research Center to quantify seal leakage and power loss at various temperatures, seal pressure differentials, and surface speeds. Data from annular and labyrinth seals are compared with previous brush and finger seal test results. Data are also compared to literature. Annular and labyrinth seal leakage rates are 2 to 3 times greater than brush and finger seal rates. Seal leakage decreases with increasing speed but increases with increasing test temperature due to thermal expansion mismatch. Also seal power loss increases with surface speed, seal pressure differential, mass flow rate, and radial clearance. Annular and labyrinth seal power losses were higher than those of brush or finger seal data. The brush seal power loss was 15 to 30 percent lower than annular and labyrinth seal power loss.

The impacts of the atmospheric annular mode on the AMOC and its feedback in an idealized experiment

NASA Astrophysics Data System (ADS)

Santis, Wlademir; Aimola, Luis; Campos, Edmo J. D.; Castellanos, Paola

2018-03-01

The interdecadal variability of the atmospheric and oceanic meridional overturning circulation is studied, using a coupled model with two narrow meridional barriers representing the land and a flat bottomed Aquaplanet. Empirical orthogonal function (EOF) analysis are used in the atmospheric and oceanic meridional overturning cells, revealing the atmospheric interdecadal variability is dominated by an annular mode, in both hemispheres, which introduces in the ocean a set of patterns of variability. The most energetic EOFs in the ocean are the barotropic responses from the annular mode. The interaction between the heat anomalies, due to the barotropic response, and the thermohaline circulation of each basin leads to a resonance mechanism that feeds back to the atmospheric forcing, modulating the annular mode spectrum. Besides the barotropic response, the annular mode introduces anomalies of salinity and temperature in the subtropical Atlantic that affects its upper buoyancy. These anomalies are incorporated within the ocean circulation and advected until the areas of deep sinking in the northern Atlantic, impacting on its overturning circulation as well.

Photoacoustics and speed-of-sound dual mode imaging with a long depth-of-field by using annular ultrasound array.

PubMed

Ding, Qiuning; Tao, Chao; Liu, Xiaojun

2017-03-20

Speed-of-sound and optical absorption reflect the structure and function of tissues from different aspects. A dual-mode microscopy system based on a concentric annular ultrasound array is proposed to simultaneously acquire the long depth-of-field images of speed-of-sound and optical absorption of inhomogeneous samples. First, speed-of-sound is decoded from the signal delay between each element of the annular array. The measured speed-of-sound could not only be used as an image contrast, but also improve the resolution and accuracy of spatial location of photoacoustic image in inhomogeneous acoustic media. Secondly, benefitting from dynamic focusing of annular array and the measured speed-of-sound, it is achieved an advanced acoustic-resolution photoacoustic microscopy with a precise position and a long depth-of-field. The performance of the dual-mode imaging system has been experimentally examined by using a custom-made annular array. The proposed dual-mode microscopy might have the significances in monitoring the biological physiological and pathological processes.

Nuclear reactor

DOEpatents

Thomson, Wallace B.

2004-03-16

A nuclear reactor comprising a cylindrical pressure vessel, an elongated annular core centrally disposed within and spaced from the pressure vessel, and a plurality of ducts disposed longitudinally of the pressure vessel about the periphery thereof, said core comprising an annular active portion, an annular reflector just inside the active portion, and an annular reflector just outside the active a portion, said annular active portion comprising rectangular slab, porous fuel elements radially disposed around the inner reflector and extending the length of the active portion, wedge-shaped, porous moderator elements disposed adjacent one face of each fuel element and extending the length of the fuel element, the fuel and moderator elements being oriented so that the fuel elements face each other and the moderator elements do likewise, adjacent moderator elements being spaced to provide air inlet channels, and adjacent fuel elements being spaced to provide air outlet channels which communicate with the interior of the peripheral ducts, and means for introducing air into the air inlet channels which passes through the porous moderator elements and porous fuel elements to the outlet channel.

Imaging characteristics of Zernike and annular polynomial aberrations.

PubMed

Mahajan, Virendra N; Díaz, José Antonio

2013-04-01

The general equations for the point-spread function (PSF) and optical transfer function (OTF) are given for any pupil shape, and they are applied to optical imaging systems with circular and annular pupils. The symmetry properties of the PSF, the real and imaginary parts of the OTF, and the modulation transfer function (MTF) of a system with a circular pupil aberrated by a Zernike circle polynomial aberration are derived. The interferograms and PSFs are illustrated for some typical polynomial aberrations with a sigma value of one wave, and 3D PSFs and MTFs are shown for 0.1 wave. The Strehl ratio is also calculated for polynomial aberrations with a sigma value of 0.1 wave, and shown to be well estimated from the sigma value. The numerical results are compared with the corresponding results in the literature. Because of the same angular dependence of the corresponding annular and circle polynomial aberrations, the symmetry properties of systems with annular pupils aberrated by an annular polynomial aberration are the same as those for a circular pupil aberrated by a corresponding circle polynomial aberration. They are also illustrated with numerical examples.

High-Frequency Chirp Ultrasound Imaging with an Annular-array for Ophthalmologic and Small-Animal Imaging

PubMed Central

Mamou, Jonathan; Aristizábal, Orlando; Silverman, Ronald H.; Ketterling, Jeffrey A.; Turnbull, Daniel H.

2009-01-01

High-frequency ultrasound (HFU, > 20 MHz) is an attractive means of obtaining fine-resolution images of biological tissues for ophthalmologic, dermatological, and small-animal imaging applications. Even with current improvements in circuit designs and high-frequency equipment, HFU suffers from two inherent limitations. First, HFU images have a limited depth of field (DOF) because of the short wavelength and the low fixed F-number of conventional HFU transducers. Second, HFU is usually limited to shallow imaging because of the significant attenuation in most tissues. In a previous study, a five-element annular array with a 17-MHz center frequency was excited using chirp-coded signals, and a synthetic-focusing algorithm was used to extend the DOF and increase penetration depth. In the present study, a similar approach with two different five-element annular arrays operating near a center frequency of 35-MHz is implemented and validated. Following validation studies, the chirp-imaging methods were applied to imaging vitreous-hemorrhage mimicking phantoms and mouse embryos. Images of the vitreous phantom showed increased sensitivity using the chirp method compared to a standard monocycle imaging method, and blood droplets could be visualized 4 mm deeper into the phantom. Three-dimensional datasets of 12.5-day-old, mouse-embryo heads were acquired in utero using chirp and conventional excitations. Images were formed and brains ventricles were segmented and reconstructed in three dimensions. The brain-ventricle volumes for the monocycle excitation exhibited artifacts that were not apparent on the chirp-based dataset reconstruction. PMID:19394754

Pressure-actuated joint system

NASA Technical Reports Server (NTRS)

McGuire, John R. (Inventor)

2004-01-01

A pressure vessel is provided that includes first and second case segments mated with one another. First and second annular rubber layers are disposed inboard of the first and second case segments, respectively. The second annular rubber layer has a slot extending from the radial inner surface across a portion of its thickness to define a main body portion and a flexible portion. The flexible portion has an interfacing surface portion abutting against an interfacing surface portion of the first annular rubber layer to follow movement of the first annular rubber layer during operation of the pressure vessel. The slot receives pressurized gas and establishes a pressure-actuated joint between the interfacing surface portions. At least one of the interfacing surface portions has a plurality of enclosed and sealed recesses formed therein.

Radius of curvature variations for annular, dark hollow and flat topped beams in turbulence

NASA Astrophysics Data System (ADS)

Eyyuboğlu, H. T.; Baykal, Y. K.; Ji, X. L.

2010-06-01

For propagation in turbulent atmosphere, the radius of curvature variations for annular, dark hollow and flat topped beams are examined under a single formulation. Our results show that for collimated beams, when examined against propagation length, the dark hollow, flat topped and annular Gaussian beams behave nearly the same as the Gaussian beam, but have larger radius of curvature values. Increased partial coherence and turbulence levels tend to lower the radius of curvature. Bigger source sizes on the other hand give rise to larger radius of curvature. Dark hollow and flat topped beams have reduced radius of curvature at longer wavelengths, whereas the annular Gaussian beam seems to be unaffected by wavelength changes; the radius of curvature of the Gaussian beam meanwhile rises with increasing wavelength.

Imaging performance of annular apertures. II - Line spread functions

NASA Technical Reports Server (NTRS)

Tschunko, H. F. A.

1978-01-01

Line images formed by aberration-free optical systems with annular apertures are investigated in the whole range of central obstruction ratios. Annular apertures form lines images with central and side line groups. The number of lines in each line group is given by the ratio of the outer diameter of the annular aperture divided by the width of the annulus. The theoretical energy fraction of 0.889 in the central line of the image formed by an unobstructed aperture increases for centrally obstructed apertures to 0.932 for the central line group. Energy fractions for the central and side line groups are practically constant for all obstruction ratios and for each line group. The illumination of rectangular secondary apertures of various length/width ratios by apertures of various obstruction ratios is discussed.

Research on Plasma Synthetic Jet Actuator

NASA Astrophysics Data System (ADS)

Che, X. K.; Nie, W. S.; Hou, Z. Y.

2011-09-01

Circular dielectric barrier surface discharge (DBDs) actuator is a new concept of zero mass synthetic jet actuator. The characteristic of discharge and flow control effect of annular-circular plasma synthetic jet actuator has been studied by means of of numerical simulation and experiment. The discharge current density, electron density, electrostatic body force density and flowfield have been obtained. The results show annular-circular actuator can produce normal jet whose velocity will be greater than 2.0 m/s. The jet will excite circumfluence. In order to insure the discharge is generated in the exposed electrode annular and produce centripetal and normal electrostatic body force, the width and annular diameter of exposed electrode must be big enough, or an opposite phase drove voltage potential should be applied between the two electrodes.

Oscillation Characteristics of Thermocapillary Convection in An Open Annular Pool

NASA Astrophysics Data System (ADS)

Duan, Li; Kang, Qi; Zhang, Di

2016-07-01

Temperature oscillation characteristics and free surface deformation are essential phenomena in fluids with free surface. We report experimental oscillatory behaviors for hydrothermal wave instability in thermocapillary-driven flow in an open annular pool of silicone oil. The annular pool is heated from the inner cylindrical wall with the radius 4mm and cooled at the outer wall with radius 20mm, and the depth of the silicone oil layer is in the range of 0.8mm-3mm.Temperature difference between the two sidewalls was increased gradually, and the flow will become unstable via a super critical temperature difference. In the present paper we used T-type thermocouple measuring the single-point temperature inside the liquid layer and captured the tiny micrometer wave signal through a high-precision laser displacement sensor. The critical temperature difference and critical Ma number of onset of oscillation have been obtained. We discussed the critical temperature difference and critical Marangoni number varies with the change of the depth of liquid layer, and the relationship between the temperature oscillation and surface oscillation has been discussed. Experimental results show that temperature oscillation and surface oscillation start almost at the same time with similar spectrum characteristic.

Gas flow stabilized megavolt spark gap for repetitive pulses

DOEpatents

Lawson, R.N.; O'Malley, M.W.; Rohwein, G.J.

A high voltage spark gap switch is disclosed including a housing having first and second end walls being spaced apart by a predetermined distance. A first electrode is positioned on the first end wall and a second electrode is positioned on the second end wall. The first and second electrodes are operatively disposed relative to each other and are spaced apart by a predetermined gap. An inlet conduit is provided for supplying gas to the first electrode. The conduit includes a nozzle for dispersing the gas in the shape of an annular jet. The gas is supplied into the housing at a predetermined velocity. A venturi housing is disposed within the second electrode. An exhaust conduit is provided for discharging gas and residue from the housing. The gas supplied at the predetermined velocity to the housing through the inlet conduit and the nozzle in an annular shape traverses the gap between the first and second electrodes and entrains low velocity gas within the housing decreasing the velocity of the gas supplied to the housing and increasing the diameter of the annular shape. The venturi disposed within the second electrode recirculates a large volume of gas to clean and cool the surface of the electrodes.

Gas flow stabilized megavolt spark gap for repetitive pulses

DOEpatents

Lawson, Robert N.; O'Malley, Martin W.; Rohwein, Gerald J.

1986-01-01

A high voltage spark gap switch including a housing having first and second end walls being spaced apart by a predetermined distance. A first electrode is positioned on the first end wall and a second electrode is positioned on the second end wall. The first and second electrodes are operatively disposed relative to each other and are spaced apart by a predetermined gap. An inlet conduit is provided for supplying gas to the first electrode. The conduit includes a nozzle for dispersing the gas in the shape of an annular jet. The gas is supplied into the housing at a predetermined velocity. A venturi housing is disposed within the second electrode. An exhaust conduit is provided for discharging gas and residue from the housing. The gas supplied at the predetermined velocity to the housing through the inlet conduit and the nozzle in an annular shape traverses the gap between the first and second electrodes and entrains low velocity gas within the housing decreasing the velocity of the gas supplied to the housing and increasing the diameter of the annular shape. The venturi disposed within the second electrode recirculates a large volume of gas to clean and cool the surface of the electrodes.

Portal Annular Pancreas

PubMed Central

Harnoss, Jonathan M.; Harnoss, Julian C.; Diener, Markus K.; Contin, Pietro; Ulrich, Alexis B.; Büchler, Markus W.; Schmitz-Winnenthal, Friedrich H.

2014-01-01

Abstract Portal annular pancreas (PAP) is an asymptomatic congenital pancreas anomaly, in which portal and/or mesenteric veins are encased by pancreas tissue. The aim of the study was to determine the role of PAP in pancreatic surgery as well as its management and potential complication, specifically, postoperative pancreatic fistula (POPF). On the basis of a case report, the MEDLINE and ISI Web of Science databases were systematically reviewed up to September 2012. All articles describing a case of PAP were considered. In summary, 21 studies with 59 cases were included. The overall prevalence of PAP was 2.4% and the patients' mean (SD) age was 55.9 (16.2) years. The POPF rate in patients with PAP (12 pancreaticoduodenectomies and 3 distal pancreatectomies) was 46.7% (in accordance with the definition of the International Study Group of Pancreatic Surgery). Portal annular pancreas is a quite unattended pancreatic variant with high prevalence and therefore still remains a clinical challenge to avoid postoperative complications. To decrease the risk for POPF, attentive preoperative diagnostics should also focus on PAP. In pancreaticoduodenectomy, a shift of the resection plane to the pancreas tail should be considered; in extensive pancreatectomy, coverage of the pancreatic remnant by the falciform ligament could be a treatment option. PMID:25207658

A newly thermoactive and detergent-stable lipase from annular sea bream (Diplodus annularis): Biochemical properties.

PubMed

Smichi, Nabil; Miled, Nabil; Gargouri, Youssef; Fendri, Ahmed

2017-01-01

A lipolytic activity was located in the annular seabream pyloric caeca, from which a digestive lipase (AsDL) was purified. Pure AsDL has an apparent molecular mass of 50 kDa. The purified lipase is thermoactive as it displays its maximal activity on short- and long-chain triacylglycerols at a temperature of 50 °C. The enzyme is alkaline resistant as it retains 90% of its maximal activity when incubated during 1 H at pH 10. No colipase was detected in the annular seabream pyloric caeca. Similar results were reported for the sardine and the gray mullet digestive systems. This is in line with the idea that colipase might have evolved in mammal animals simultaneously with the appearance of an exocrine pancreas. AsDL is a serine enzyme, like all known lipases from different origins. Interestingly, the pure lipase was found to be insensitive to Triton X-100, a synthetic detergent, addition even at a concentration as high as 12 mM. The purified enzyme has potential applications in detergent and food industry because of its thermal activity and alkaline nature. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

Annular flow in rod-bundle: Effect of spacer on disturbance waves

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

Pham, Son H.; Kunugi, Tomoaki

2016-08-01

A high-speed camera technique is used to study the effect of spacers on the disturbance waves present in annular two-phase flow within a rod-bundle geometry. Images obtained using a backlight configuration to visualize the spacer-wave interactions at the micro-scale resolution (in time and space) are discussed. This paper also presents additional images obtained using a reflected light configuration which provides new observations of the disturbance waves. These images show the separation effect caused by the spacer on the liquid film in which the size of generated liquid droplets can be controlled by the gas superficial velocity. Furthermore, the data confirmmore » that the spacer breaks the circumferential coherent structures of the waves.« less

A study of the transient performance of annular hydrostatic journal bearings in liquid oxygen

NASA Astrophysics Data System (ADS)

Scharrer, J. K.; Tellier, J. G.; Hibbs, R. I.

1992-07-01

A test apparatus was used to simulate a cryogenic turbopump start transient in order to determine the liftoff and touchdown speed and amount of wear of an annular hydrostatic bearing in liquid oxygen. The bearing was made of sterling silver and the journal made of Inconel 718. The target application of this configuration is the pump end bearing of the Space Shuttle Main Engine High Pressure Liquid Oxygen Turbopump. Sixty-one transient cycles were performed in liquid oxygen with an additional three tests in liquid nitrogen to certify the test facility and configuration. The bearing showed no appreciable wear during the testing, and the results indicate that the performance of the bearing was not significantly degraded during the testing.

Effects of Annular Electromagnetic Stirring Coupled with Intercooling on Grain Refinement and Homogeneity During Direct Chill Casting of Large-Sized 7005 Alloy Billet

NASA Astrophysics Data System (ADS)

Luo, Yajun; Zhang, Zhifeng; Li, Bao; Gao, Mingwei; Qiu, Yang; He, Min

2017-12-01

To obtain a large-sized, high-quality aluminum alloy billet, an advanced uniform direct chill (UDC) casting method was developed by combining annular electromagnetic stirring (A-EMS) with intercooling in the sump. The 7005 alloy was chosen to investigate the effect of UDC on grain refinement and homogeneity during normal direct chill (NDC) casting. It was concluded that the microstructure consisting of both primary α-Al phase and secondary phases becomes finer and more homogeneous for the billets prepared with UDC casting compared to those prepared with NDC casting, and the forced cooling from both the inner and outer melt under A-EMS has a measurable effect on grain refinement and homogeneity.

Functional specifications of the annular suspension pointing system, appendix A

NASA Technical Reports Server (NTRS)

Edwards, B.

1980-01-01

The Annular Suspension Pointing System is described. The Design Realization, Evaluation and Modelling (DREAM) system, and its design description technique, the DREAM Design Notation (DDN) is employed.

Optimal design of high damping force engine mount featuring MR valve structure with both annular and radial flow paths

NASA Astrophysics Data System (ADS)

Nguyen, Q. H.; Choi, S. B.; Lee, Y. S.; Han, M. S.

2013-11-01

This paper focuses on the optimal design of a compact and high damping force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high damping force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum damping force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the ‘lockup’ problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting damping force and power consumption.

Thin-Film Evaporative Cooling for Side-Pumped Laser

NASA Technical Reports Server (NTRS)

Stewart, Brian K. (Inventor)

2010-01-01

A system and method are provided for cooling a crystal rod of a side-pumped laser. A transparent housing receives the crystal rod therethrough so that an annular gap is defined between the housing and the radial surface of the crystal rod. A fluid coolant is injected into the annular gap such the annular gap is partially filled with the fluid coolant while the radial surface of the crystal rod is wetted as a thin film all along the axial length thereof.

Method of forming aperture plate for electron microscope

NASA Technical Reports Server (NTRS)

Heinemann, K. (Inventor)

1974-01-01

An electron microscope is described with an electron source a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen. It also has objective lens with an annular objective aperture, for focusing electrons passing through the specimen onto an image plane. A method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques is included.

Removable, hermetically-sealing, filter attachment system for hostile environments

DOEpatents

Mayfield, Glenn L [Richland, WA

1983-01-01

A removable and reusable filter attachment system. A filter medium is fixed o, and surrounded by, a filter frame having a coaxial, longitudinally extending, annular rim. The rim engages an annular groove which surrounds the opening of a filter housing. The annular groove contains a fusible material and a heating mechanism for melting the fusible material. Upon resolidifying, the fusible material forms a hermetic bond with the rim and groove. Remelting allows detachment and replacement of the filter frame.

Propeller blade retention system

NASA Technical Reports Server (NTRS)

Elston, III, Sidney B. (Inventor); Simon, III, Victor H. (Inventor); Tseng, Wu-Yang (Inventor); Butler, Lawrence (Inventor)

1993-01-01

The invention concerns the mounting of propeller blades to a ring-shaped rotor. The blades are of the variable pitch type, and the shank of each blade extends through a respective hole in the rotor. Each hole contains an annular shelf which is fastened to the wall of the hole and surrounds each shank. Each shank bears a pair of bearing races which sandwich the annular shelf in order to connect the blade to the rotor. Bearing rollers are positioned between the annular shelf and the bearing races.

APPARATUS FOR ARC WELDING

DOEpatents

Lingafelter, J.W.

1960-04-01

An apparatus is described in which a welding arc created between an annular electrode and a workpiece moves under the influence of an electromagnetic field about the electrode in a closed or annular path. This mode of welding is specially suited to the enclosing of nuclear-fuel slugs in a protective casing. For example, a uranium slug is placed in an aluminum can, and an aluminum closure is welded to the open end of the can along a closed or annular path conforming to the periphery of the end closure.

Design, Fabrication and Testing of an Axisymmetric, Annular, Subsonic Diffuser and Associated Instrumentation Systems

DTIC Science & Technology

1981-12-01

this investigation are threefold. First, an annular diffuser is to be designed and built to model the annulardiffuser arranged between the compressor ...on these calculations. The final design of the diffuser model (Figs 7, 8, 12 1and 9) was 20 in in diameter at the inlet. The axial annular sections...traversing mechanism was designed and built (Fig 18). It was constructed so that all peripheral data stations at one axial point could be used either

Terrain Traversing Device Having a Wheel with Microhooks

NASA Technical Reports Server (NTRS)

Parness, Aaron (Inventor); McKenzie, Clifford F. (Inventor)

2014-01-01

A terrain traversing device includes an annular rotor element with a plurality of co-planar microspine hooks arranged on the periphery of the annular rotor element. Each microspine hook has an independently flexible suspension configuration that permits the microspine hook to initially engage an irregularity in a terrain surface at a preset initial engagement angle and subsequently engage the irregularity with a continuously varying engagement angle when the annular rotor element is rotated for urging the terrain traversing device to traverse a terrain surface.

Deep Granuloma Annulare Mimicking Inflamed Cysts in a Teenager.

PubMed

Guo, Emily L; Degesys, Catherine A; Jahan-Tigh, Richard; Chan, Audrey

2017-07-01

We describe deep granuloma annulare (DGA) of the forehead mimicking inflamed cysts. Reactive inflammation and sterile purulent drainage may be an underrecognized feature of DGA. © 2017 Wiley Periodicals, Inc.

Annular pancreas (image)

MedlinePlus

Annular pancreas is an abnormal ring or collar of pancreatic tissue that encircles the duodenum (the part of the ... intestine that connects to stomach). This portion of pancreas can constrict the duodenum and block or impair ...

Coherent Structures and Chaos Control in High-Power Microwave Devices

DTIC Science & Technology

2006-06-29

Theory of Multiresonator Cylindrical Magnetrons 2. High - Power Klystron Research 9 2.1. Determination of the Current Limit on the Confinement of Finite...Size Bunched Pencil Beams in High - Power Relativistic Klystrons 2.2. Exploration of the Possibility of Magnetic Cusp Formation in Highly Bunched...Annular Beams in High - Power Relativistic Klystrons 3. Development of Ellipse-Shaped Ribbon-Beam Theory for HPM Device Applications 12 3.1. Theory of

Development of probabilistic design method for annular fuels

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

Ozawa, Takayuki

2007-07-01

The increase of linear power and burn-up during the reactor operation is considered as one measure to ensure the utility of fast reactors in the future; for this the application of annular oxide fuels is under consideration. The annular fuel design code CEPTAR was developed in the Japan Atomic Energy Agency (JAEA) and verified by using many irradiation experiences with oxide fuels. In addition, the probabilistic fuel design code BORNFREE was also developed to provide a safe and reasonable fuel design and to evaluate the design margins quantitatively. This study aimed at the development of a probabilistic design method formore » annular oxide fuels; this was implemented in the developed BORNFREE-CEPTAR code, and the code was used to make a probabilistic evaluation with regard to the permissive linear power. (author)« less

Design of wavefront coding optical system with annular aperture

NASA Astrophysics Data System (ADS)

Chen, Xinhua; Zhou, Jiankang; Shen, Weimin

2016-10-01

Wavefront coding can extend the depth of field of traditional optical system by inserting a phase mask into the pupil plane. In this paper, the point spread function (PSF) of wavefront coding system with annular aperture are analyzed. Stationary phase method and fast Fourier transform (FFT) method are used to compute the diffraction integral respectively. The OTF invariance is analyzed for the annular aperture with cubic phase mask under different obscuration ratio. With these analysis results, a wavefront coding system using Maksutov-Cassegrain configuration is designed finally. It is an F/8.21 catadioptric system with annular aperture, and its focal length is 821mm. The strength of the cubic phase mask is optimized with user-defined operand in Zemax. The Wiener filtering algorithm is used to restore the images and the numerical simulation proves the validity of the design.

Analytic wave solution with helicon and Trivelpiece-Gould modes in an annular plasma

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

Carlsson, Johan; Pavarin, Daniele; Walker, Mitchell

2009-11-26

Helicon sources in an annular configuration have applications for plasma thrusters. The theory of Klozenberg et al.[J. P. Klozenberg B. McNamara and P. C. Thonemann, J. Fluid Mech. 21(1965) 545-563] for the propagation and absorption of helicon and Trivelpiece-Gould modes in a cylindrical plasma has been generalized for annular plasmas. Analytic solutions are found also in the annular case, but in the presence of both helicon and Trivelpiece-Gould modes, a heterogeneous linear system of equations must be solved to match the plasma and inner and outer vacuum solutions. The linear system can be ill-conditioned or even exactly singular, leading tomore » a dispersion relation with a discrete set of discontinuities. The coefficients for the analytic solution are calculated by solving the linear system with singular-value decomposition.« less

Radical antegrade modular pancreatosplenectomy for adenocarcinomaof the body of the pancreas in a patient with portal annular pancreas, aberrant hepatic artery, and absence of the celiac trunk

PubMed Central

Yuan, Hao; Wu, Pengfei; Chen, Jianmin; Lu, Zipeng; Chen, Lei; Wei, Jishu; Guo, Feng; Cai, Baobao; Yin, Jie; Xu, Dong; Jiang, Kuirong; Miao, Yi

2017-01-01

Abstract Rationale: Portal annular pancreas is a rare anatomic variation, where the uncinated process of the pancreas connects with the dorsal pancreas and the pancreas tissue encases the portal vein (PV), superior mesenteric vein (SMV) or splenic vein (SV). Malignancies are quite uncommon in the patients, who have an annular pancreas especially portal annular pancreas. Ectopic common hepatic artery and absence of the celiac trunk (CT) are the other infrequent abnormalities. Patient concerns: A 74-year-old man suffered from upper abdominal and back pain. Diagnoses and Interventions: Contrast enhanced computed tomography indicated a low-density mass in the body of the pancreas. Pathological report showed adenocarcinoma of the body of pancreas after radical antegrade modular pancreatosplenectomy (RAMPS). Outcomes: In the operation, we found the superior vein and portal vein was surrounded by the pancreatic tissue. The left gastric artery and splenic artery originated respectively from abdominal aorta, and celiac trunk was not viewed. In addition, the common hepatic artery was a branch from the superior mesenteric artery. Lessons: In general, this is a novel clinical case of pancreatic carcinoma happening in the portal annular pancreas which was accompanied with aberrant hepatic artery and absence of the celiac trunk at the same time. Confronted with the pancreatic neoplasms, the possibility of coexistent annular pancreas and arterial variations should be considered. PMID:29310347

Does perineural invasion of the myenteric plexus have a key role in annular rectal invasion and digestive system symptoms of prostate carcinoma patients?

PubMed

Hashimoto, Hirotsugu; Kurata, Atsushi; Nashiro, Tamaki; Kuroda, Masahiko; Horiuchi, Hajime

2015-12-01

Prostate carcinoma is one of the most common cancers globally. It relatively rarely invades the rectum, accounting for only about 4% of resected cases. About half of these cases of rectal invasion show an annular rectal stricture pattern. It has been hypothesized that anatomical structures, namely Denonvilliers fascia, may play an important role in annular rectal involvement of prostate carcinoma. Here, we propose another hypothesis: the reason for annular rectal invasion by prostate carcinoma is its extension along the myenteric plexus (Auerbach's plexus). We illustrate this using a case presentation and description of the symptoms of such cases. From a review of the literature, autonomic digestive system symptoms of rectal invasion of prostatic carcinoma, such as diarrhea, tenesmus, or fecal incontinence is seen in about half of cases, coinciding with the frequency of annular rectal invasion. Thus, by modifying the long-established hypothesis, our suggestion that prostate carcinoma spreads along the myenteric plexus when cancer cells invade beyond the Denonvilliers fascia to the rectum could explain the cause and frequency not only of the annular rectal invasion but also the digestive system symptoms related to this disease. The prognosis of prostate carcinoma invading the rectum is very poor; however, this new hypothesis might shed light on the digestive system symptoms associated with prostate carcinoma and might lead to recognition and treatment of these cases at a relatively early stage of rectal invasion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantification of annular dilatation and papillary muscle separation in functional mitral regurgitation: role of anterior mitral leaflet length as reference.

PubMed

Jorapur, Vinod; Voudouris, Apostolos; Lucariello, Richard J

2005-07-01

We hypothesized that anterior mitral leaflet length (ALL) does not differ significantly between normal subjects and patients with functional mitral regurgitation (FMR) and hence may be used as a reference measurement to quantify annular dilatation and papillary muscle separation. We prospectively studied 50 controls, 15 patients with systolic left ventricular dysfunction (LVD) with significant FMR, and 15 patients with LVD without significant FMR. Significant MR was defined as an effective regurgitant orifice area > or = 0.2 cm2 as measured by the flow convergence method. Annular diameter, interpapillary distance, and ALL were measured, and the following ratios were derived: annular diameter indexed to ALL (ADI) and interpapillary distance indexed to ALL (IPDI). There was no significant difference in ALL among the three groups. The mean ADI was 1.26 times controls in patients with LVD without significant FMR compared to 1.33 times controls in patients with LVD with significant FMR (P = 0.06, no significant difference between groups). The mean IPDI was 1.42 times controls in patients with LVD without significant FMR compared to 2.1 times controls in patients with LVD with significant FMR (P < 0.0001, significant difference between groups). There was no significant difference in ALL between controls and patients with LVD. ALL can be used as a reference measurement to quantify annular dilatation and papillary muscle separation in patients with FMR. Interpapillary distance but not annular diameter indexed to ALL correlates with severity of FMR.

All optical detection of picosecond spin-wave dynamics in 2D annular antidot lattice

NASA Astrophysics Data System (ADS)

Porwal, Nikita; Mondal, Sucheta; Choudhury, Samiran; De, Anulekha; Sinha, Jaivardhan; Barman, Anjan; Datta, Prasanta Kumar

2018-02-01

Novel magnetic structures with precisely controlled dimensions and shapes at the nanoscale have potential applications in spin logic, spintronics and other spin-based communication devices. We report the fabrication of 2D bi-structure magnonic crystal in the form of embedded nanodots in a periodic Ni80Fe20 antidot lattice structure (annular antidot) by focused ion-beam lithography. The spin-wave spectra of the annular antidot sample, studied for the first time by a time-resolved magneto-optic Kerr effect microscopy show a remarkable variation with bias field, which is important for the above device applications. The optically induced spin-wave spectra show multiple modes in the frequency range 14.7 GHz-3.5 GHz due to collective interactions between the dots and antidots as well as the annular elements within the whole array. Numerical simulations qualitatively reproduce the experimental results, and simulated mode profiles reveal the spatial distribution of the spin-wave modes and internal magnetic fields responsible for these observations. It is observed that the internal field strength increases by about 200 Oe inside each dot embedded within the hole of annular antidot lattice as compared to pure antidot lattice and pure dot lattice. The stray field for the annular antidot lattice is found to be significant (0.8 kOe) as opposed to the negligible values of the same for the pure dot lattice and pure antidot lattice. Our findings open up new possibilities for development of novel artificial crystals.

Effects of annulus defects and implantation of poly(lactic-co-glycolic acid) (PLGA)/fibrin gel scaffolds on nerves ingrowth in a rabbit model of annular injury disc degeneration.

PubMed

Xin, Long; Xu, Weixing; Yu, Leijun; Fan, Shunwu; Wang, Wei; Yu, Fang; Wang, Zhenbin

2017-05-12

Growth of nerve fibers has been shown to occur in a rabbit model of intravertebral disc degeneration (IVD) induced by needle puncture. As nerve growth may underlie the process of chronic pain in humans affected by disc degeneration, we sought to investigate the factors underlying nerve ingrowth in a minimally invasive annulotomy rabbit model of IVD by comparing the effects of empty disc defects with those of defects filled with poly(lactic-co-glycolic acid)/fibrin gel (PLGA) plugs. New Zealand white rabbits (n = 24) received annular injuries at three lumbar levels (L3/4, L4/5, and L5/6). The discs were randomly assigned to four groups: (a) annular defect (1.8-mm diameter; 4-mm depth) by mini-trephine, (b) annular defect implanted with a PLGA scaffold containing a fibrin gel, (c) annular puncture by a 16G needle (5-mm depth), and (d) uninjured L2/3 disc (control). Disc degeneration was evaluated by radiography, MRI, histology, real-time PCR, and analysis of proteoglycan (PG) content. Nerve ingrowth into the discs was assessed by immunostaining with the nerve marker protein gene product 9.5. Injured discs showed a progressive disc space narrowing with significant disc degeneration and proteoglycan loss, as confirmed by imaging results, molecular and compositional analysis, and histological examinations. In 16G punctured discs, nerve ingrowth was observed on the surface of scar tissue. In annular defects, nerve fibers were found to be distributed along small fissures within the fibrocartilaginous-like tissue that filled the AF. In discs filled with PLGA/ fibrin gel, more nerve fibers were observed growing deeper into the inner AF along the open annular track.  In addition, innervations scores showed significantly higher than those of punctured discs and empty defects. A limited vascular proliferation was found in the injured sites and regenerated tissues. Nerve ingrowth was significantly higher in PLGA/fibrin-filled discs than in empty defects. Possible explanations include (i) annular fissures along the defect and early loss of proteoglycan may facilitate the ingrowth process and (ii) biodegradable PLGA/fibrin gel may promote adverse growth of nerves and blood vessels into deeper parts of injured disc. The rabbit annular defect model of disc degeneration appears suitable to investigate the effects of nerve ingrowth in relation to pain generation.

Rotary union for use with ultrasonic thickness measuring probe

DOEpatents

Nachbar, H.D.

1992-09-15

A rotary union for rotatably supporting an ultrasonic probe operable to nondestructively measure the thickness of steam generator tubes to determine the amount of corrosion experienced by the tubes includes a stationary body having a bore therethrough and an outlet drain, and a fitting rotatably mounted within the upper end of the body. The fitting has a bore aligned with the bore of the body. An electrical cable positioned within a water supply tube in an annular arrangement passes through the bore of the body and the bore of the fitting. This annular arrangement, in turn, is positioned within a connector element which extends outwardly from the fitting bore and is connected to the ultrasonic probe. An elastomeric lower bushing seals the annular arrangement to the lower end of the rotary union body and an elastomeric upper bushing seals the connector element to the fitting to permit the connector element and the ultrasonic probe connected thereto to rotate with the fitting relative to the body. The lower and upper bushings permit water to be passed through the annular arrangement and into the ultrasonic probe and thereafter discharged between the annular arrangement and the connector element to the outlet drain of the rotary union body. 5 figs.

Right ventricular remodeling and dysfunction with subsequent annular dilatation and tethering as a mechanism of isolated tricuspid regurgitation.

PubMed

Seo, Hye-Sun; Ha, Jong-Won; Moon, Jae Youn; Choi, Eui-Young; Rim, Se-Joong; Jang, Yangsoo; Chung, Namsik; Shim, Won-Heum; Cho, Seung-Yun; Kim, Sung Soon

2008-10-01

Secondary tricuspid regurgitation (TR) as a result of pulmonary hypertension and/or left-sided heart disease is caused by tricuspid valve (TV) annular dilatation and tethering of the tricuspid leaflet after right ventricular (RV) dilatation. However, the mechanism of isolated TR without significant pulmonary hypertension remains unknown. The present study investigated the RV function and TV deformations in patients with isolated TR to find out the mechanism and etiology of the disease. Twelve patients with isolated, severe TR were included. RV area, volume, ejection fraction (EF), tenting distance and tenting area were measured. These parameters were compared with 12 age-and gender-matched controls and 12 patients with secondary TR. The cause of isolated TR was incomplete coaptation associated with annular dilatation without other problems. Compared with the controls, RV end-diastolic volumes and annular diameters were significantly larger and RVEF was significantly lower in patients with isolated TR. Tenting area and tenting distance were also significantly higher. However, there were no significant differences in these parameters between patients with isolated and secondary TR. Isolated TR was associated with RV remodeling, systolic dysfunction and resultant annular dilatation and tethering of tricuspid leaflets.

Annular Internal-External-Expansion Rocket Nozzles for Large Booster Applications

NASA Technical Reports Server (NTRS)

Connors, James F.; Cubbison, Robert W.; Mitchell, Glenn A.

1961-01-01

For large-thrust booster applications, annular rocket nozzles employing both internal and external expansion are investigated. In these nozzles, free-stream air flows through the center as well as around the outside of the exiting jet. Flaps for deflecting the rocket exhaust are incorporated on the external-expansion surface for thrust-vector control. In order to define nozzle off-design performance, thrust vectoring effectiveness, and external stream effects, an experimental investigation was conducted on two annular nozzles with area ratios of 15 and 25 at Mach 0, 2, and 3 in the Lewis 10- by 10-foot wind tunnel. Air, pressurized to 600 pounds per square inch absolute, was used to simulate the exhaust flow. For a nozzle-pressure-ratio range of 40 to 1000, the ratio of actual to ideal thrust was essentially constant at 0.98 for both nozzles. Compared with conventional convergent-divergent configurations on hypothetical boost missions, the performance gains of the annular nozzle could yield significant orbital payload increases (possibly 8 to 17 percent). A single flap on the external-expansion surface of the area-ratio-25 annular nozzle produced a side force equal to 4 percent of the axial force with no measurable loss in axial thrust.

Performance of an annular solid-oxide fuel cell micro-stack array operating in single-chamber conditions

NASA Astrophysics Data System (ADS)

Liu, Mingliang; Lü, Zhe; Wei, Bo; Huang, Xiqiang; Zhang, Yaohui; Su, Wenhui

An annular micro-stack array consisting of four fuel cells has been fabricated and operated successfully in single-chamber conditions using a nitrogen-diluted oxygen-methane mixture as the operating gas. The single cells consist of a state-of-the-art porous NiO/Y 2O 3-stabilized ZrO 2 (YSZ) anode support, a YSZ electrolyte membrane and a modified La 0.7Sr 0.3MnO 3 (LSM) cathode. The annular configuration of the array is favorable for utilizing the heating effect. The maximum power output of the annular stack decreases with increasingCH 4/O 2 ratio. Its performance increases with increasing CH 4 flow rate and decreases with increasing N 2 flow rate. The power output of the stack is ∼380 mW at CH 4/O 2 = 1 and an N 2 flow rate of 100 sccm and the average maximum power density of each cell is ∼190 mW cm -2. The average performance of each cell in the annular micro-stack array is higher than that of an additional single cell placed next to the stack.

Rotary union for use with ultrasonic thickness measuring probe

DOEpatents

Nachbar, Henry D.

1992-01-01

A rotary union for rotatably supporting an ultrasonic probe operable to nondestructively measure the thickness of steam generator tubes to determine the amount of corrosion experienced by the tubes includes a stationary body having a bore therethrough and an outlet drain, and a fitting rotatably mounted within the upper end of the body. The fitting has a bore aligned with the bore of the body. An electrical cable positioned within a water supply tube in an annular arrangement passes through the bore of the body and the bore of the fitting. This annular arrangement, in turn, is positioned within a connector element which extends outwardly from the fitting bore and is connected to the ultrasonic probe. An elastomeric lower bushing seals the annular arrangement to the lower end of the rotary union body and an elastomeric upper bushing seals the connector element to the fitting to permit the connector element and the ultrasonic probe connected thereto to rotate with the fitting relative to the body. The lower and upper bushings permit water to be passed through the annular arrangement and into the ultrasonic probe and thereafter discharged between the annular arrangement and the connector element to the outlet drain of the rotary union body.

Ballistic impulse gauge

DOEpatents

Ault, Stanley K.

1993-01-01

A gauge for detecting the impulse generated in sample materials by X-rays or other impulse producing mechanisms utilizes a pair of flat annular springs to support a plunger relative to a housing which may itself be supported by a pair of flat annular springs in a second housing. The plunger has a mounting plate mounted on one end and at the other, a position or velocity transducer is mounted. The annular springs consist of an outer ring and an inner ring with at least three arcuate members connecting the outer ring with the inner ring.

Ballistic impulse gauge

DOEpatents

Ault, S.K.

1993-12-21

A gauge for detecting the impulse generated in sample materials by X-rays or other impulse producing mechanisms utilizes a pair of flat annular springs to support a plunger relative to a housing which may itself be supported by a pair of flat annular springs in a second housing. The plunger has a mounting plate mounted on one end and at the other, a position or velocity transducer is mounted. The annular springs consist of an outer ring and an inner ring with at least three arcuate members connecting the outer ring with the inner ring. 4 figures.

Energy efficient engine

NASA Technical Reports Server (NTRS)

Burrus, D.; Sabla, P. E.; Bahr, D. W.

1980-01-01

The feasibility of meeting or closely approaching the emissions goals established for the Energy Efficient Engine (E3) Project with an advanced design, single annular combustor was determined. A total of nine sector combustor configurations and one full-annular-combustor configuration were evaluated. Acceptable levels of carbon monoxide and hydrocarbon emissions were obtained with several of the sector combustor configurations tested, and several of the configurations tested demonstrated reduced levels of nitrogen oxides compared to conventional, single annular designs. None of the configurations tested demonstrated nitrogen oxide emission levels that meet the goal of the E3 Project.

Some optical properties of one dimensional annular photonic crystal with plasma frequency

NASA Astrophysics Data System (ADS)

Pandeya, G. N.; Thapa, Khem B.

2018-05-01

This paper presents the reflection bands, photonic band gaps, of the one-dimensional annul photonic crystal (APC) containing double negative (DNG) metamaterials and air. The proposed annular structure consists of the alternate layers of dispersive DNG material and air immersed in free space. The reflectance properties of the APC by employing the transfer matrix method (TMM) in the cylindrical waves for TE polarization is studied theoretically. In addition of this, we have also studied the effect of plasma frequency on the reflection behavior of the considered annular structure.

High-voltage isolation transformer for sub-nanosecond rise time pulses constructed with annular parallel-strip transmission lines.

PubMed

Homma, Akira

2011-07-01

A novel annular parallel-strip transmission line was devised to construct high-voltage high-speed pulse isolation transformers. The transmission lines can easily realize stable high-voltage operation and good impedance matching between primary and secondary circuits. The time constant for the step response of the transformer was calculated by introducing a simple low-frequency equivalent circuit model. Results show that the relation between the time constant and low-cut-off frequency of the transformer conforms to the theory of the general first-order linear time-invariant system. Results also show that the test transformer composed of the new transmission lines can transmit about 600 ps rise time pulses across the dc potential difference of more than 150 kV with insertion loss of -2.5 dB. The measured effective time constant of 12 ns agreed exactly with the theoretically predicted value. For practical applications involving the delivery of synchronized trigger signals to a dc high-voltage electron gun station, the transformer described in this paper exhibited advantages over methods using fiber optic cables for the signal transfer system. This transformer has no jitter or breakdown problems that invariably occur in active circuit components.

A novel sandwich-type traveling wave piezoelectric tracked mobile system.

PubMed

Wang, Liang; Shu, Chengyou; Zhang, Quan; Jin, Jiamei

2017-03-01

In this paper, a novel sandwich-type traveling wave piezoelectric tracked mobile system was proposed, designed, fabricated and experimentally investigated. The proposed system exhibits the advantages of simple structure, high mechanical integration, lack of electromagnetic interference, and lack of lubrication requirement, and hence shows potential application to robotic rovers for planetary exploration. The tracked mobile system is comprised of a sandwich actuating mechanism and a metal track. The actuating mechanism includes a sandwich piezoelectric transducer and two annular parts symmetrically placed at either end of the transducer, while the metal track is tensioned along the outer surfaces of the annular parts. Traveling waves with the same rotational direction are generated in the two annular parts, producing the microscopic elliptical motions of the surface particles on the annular parts. In this situation, if the pre-load is applied properly, the metal track can be driven by friction force to achieve bidirectional movement. At first, the finite element method was adopted to conduct the modal analysis and harmonic response analysis of the actuating mechanism, and the vibration characteristics were measured to confirm the operating principle. Then the optimal driving frequency of the system prototype, namely 35.1kHz, was measured by frequency sensitivity experiments. At last, the mechanical motion characteristics of the prototype were investigated experimentally. The results show that the average motion speeds of the prototype in dual directions were as 72mm/s and 61.5mm/s under the excitation voltage of 500V RMS , respectively. The optimal loading weights of the prototype in bi-directions were 0.32kg and 0.24kg with a maximum speed of 59.5mm/s and 61.67mm/s at the driving voltage of 300V RMS , respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Characteristic analysis and comparison of two kinds of hybrid plasmonic annular resonators

NASA Astrophysics Data System (ADS)

Zhou, Jie; Shi, Feifei; Zhou, Taojie; He, Kebo; Qiu, Bocang; Zhang, Zhaoyu

2017-04-01

We designed two kinds of hybrid plasmonic annular resonators with different cross-sectional shapes, i.e., a square and circle called "square ring" and "circle ring" resonators, respectively. Both resonators feature an ultracompact mode volume of ˜10-4 μm3 and a relatively high-quality factor of ˜102 at a submicron footprint within our studied wavelength range from 400 to 900 nm. Their performance as defined by the Q/V ratio (quality factor over mode volume) is enhanced considerably with a reduction in their physical dimensions. There exists critical annular radii, which increase from 400 to 600 nm with an increase in the azimuthal numbers from m=7 to m=10, if the two types of rings are compared with the same mode numbers and same ring thickness of 120 nm. Below the critical radii, the circle ring resonator outperforms the square ring resonator in terms of the Q/V ratio, and the difference in Q/V of the two types of rings increases rapidly with the decrease of the radii. On the other hand, they have critical annular radii of ˜250 nm, below which the square ring resonator outperforms the circle ring resonator at the wavelengths of 490 and 595 nm however, the difference in Q/V of the two types of rings remains small within the radii range we consider. It is suggested that, in practice, with the consideration of the wavelength of green emission for these two ring structures with radii from 100 to 500 nm and ring thickness ˜120 nm, they have a negligible difference in Q/V performance.

Teleconnections in the Presence of Climate Change: A Case Study of the Annular Modes

NASA Astrophysics Data System (ADS)

Gerber, Edwin; Baldwin, Mark

2010-05-01

Long model integrations of future and past climates present a problem for defining teleconnection patterns through Empirical Orthogonal Function (EOF) or correlation analysis when trends in the underlying climate begin to dominate the covariance structure. Similar issues may soon appear in observations as the record becomes longer, especially if climate trends accelerate. The Northern and Southern Annular Modes provide a prime example, because the poleward shift of the jet streams strongly projects onto these patterns, particularly in the Southern Hemisphere. Climate forecasts of the 21st century by chemistry climate models provide a case study. Computation of the annular modes in these long data sets with secular trends requires refinement of the standard definition of the annular mode, and a more robust procedure that allows for slowly varying trends is established and verified. The new procedure involves two key changes. First, the global mean geopotential height is removed at each time step before computing anomalies. This is particularly important high in the atmosphere, where seasonal variations in geopotential height become significant, and filters out trends due to changes in the temperature structure of the atmosphere. Pattern definition can be very sensitive near the tropopause, as regions of the atmosphere that used to be more of stratospheric character begin to take on tropospheric characteristics as the tropopause rises. The second change is to define anomalies relative to a slowly evolving seasonal climatology, so that the covariance structure reflects internal variability. Once these changes are accounted for, it is found that the zonal mean variability of the atmosphere stays remarkably constant, despite significant changes in the baseline climate forecast for the rest of the century. This stability of the internal variability makes it possible to relate trends in climate to teleconnections.

Prediction of slug-to-annular flow pattern transition (STA) for reducing the risk of gas-lift instabilities and effective gas/liquid transport from low-pressure reservoirs

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

Toma, P.R.; Vargas, E.; Kuru, E.

Flow-pattern instabilities have frequently been observed in both conventional gas-lifting and unloading operations of water and oil in low-pressure gas and coalbed reservoirs. This paper identifies the slug-to-annular flow-pattern transition (STA) during upward gas/liquid transportation as a potential cause of flow instability in these operations. It is recommended that the slug-flow pattern be used mainly to minimize the pressure drop and gas compression work associated with gas-lifting large volumes of oil and water. Conversely, the annular flow pattern should be used during the unloading operation to produce gas with relatively small amounts of water and condensate. New and efficient artificialmore » lifting strategies are required to transport the liquid out of the depleted gas or coalbed reservoir level to the surface. This paper presents held data and laboratory measurements supporting the hypothesis that STA significantly contributes to flow instabilities and should therefore be avoided in upward gas/liquid transportation operations. Laboratory high-speed measurements of flow-pressure components under a broad range of gas-injection rates including STA have also been included to illustrate the onset of large STA-related flow-pressure oscillations. The latter body of data provides important insights into gas deliquification mechanisms and identifies potential solutions for improved gas-lifting and unloading procedures. A comparison of laboratory data with existing STA models was performed first. Selected models were then numerically tested in field situations. Effective field strategies for avoiding STA occurrence in marginal and new (offshore) field applications (i.e.. through the use of a slug or annular flow pattern regimen from the bottomhole to wellhead levels) are discussed.« less

Extradiscal ultrasound thermal therapy (ExDUSTT): evaluation in ex vivo and in vivo spine models (Invited Paper)

NASA Astrophysics Data System (ADS)

Diederich, Chris J.; Kinsey, Adam; Nau, William H.; Shu, Richard; Lotz, Jeffrey C.

2005-04-01

The application of heat to intervertebral discs is being clinically investigated for the treatment of discogenic back pain. The purpose of this study was to develop and test the feasibility of small ultrasound applicators that can be endoscopically placed adjacent to the disc, and deliver heating energy into the disc without puncturing the annular wall. Prototype devices were fabricated using curvilinear transducers (2.5-3.5 mm wide x 10 mm long, 5.4 - 6.5 MHz) that produce a narrow penetrating beam extending along the length of the ultrasound element. The transducer was affixed to either a flexible or rigid delivery catheter, and enclosed within an asymmetric coupling balloon with water-cooling flow. Bench measurements demonstrated 35-60% acoustic efficiencies, high-power output capabilities, and lightly focused beam patterns. The heating characteristics of these devices were evaluated with ex vivo and in vivo experiments within lumbar and cervical spine segments from sheep models and human cadaveric spine. The applicators were positioned adjacent to the annular wall of the surgically exposed discs. Ultrasound energy was focused directly into the disc to avoid heating the vertebral bodies. Multi-point thermocouple probes were placed throughout the disc to characterize the resultant temperature distributions. These studies demonstrated that ultrasound energy from these applicators penetrated the annular wall of the disc, and produced thermal coagulative temperatures of >60-65°C as far as 10 mm into the tissue. This study also showed that lower power levels and temperatures delivered for 10 minutes can generate a cytotoxic thermal dose of t43°C >240 min penetrating 5-10 mm from the annular wall.

Distribution characteristics of dissolved organic carbon in annular wetland soil-water solutions through soil profiles in the Sanjiang Plain, northeast China.

PubMed

Xi, Min; Lu, Xian-Guo; Li, Yue; Kong, Fan-Long

2007-01-01

Overwhelming evidence reveals that concentrations of dissolved organic carbon (DOC) have increased in streams which brings negative environmental impacts. DOC in stream flow is mainly originated from soil-water solutions of watershed. Wetlands prove to be the most sensitive areas as an important DOC reserve between terrestrial and fluvial biogeosystems. This reported study was focused on the distribution characteristics and the controlling factors of DOC in soil-water solutions of annular wetland, i.e., a dishing wetland and a forest wetland together, in the Sanjiang Plain, Northeast China. The results indicate that DOC concentrations in soil-water solutions decreased and then increased with increasing soil depth in the annular wetland. In the upper soil layers of 0-10 cm and 10-20 cm, DOC concentrations in soil-water solutions linearly increased from edge to center of the annular wetland (R2 = 0.3122 and R2 = 0.443). The distribution variations were intimately linked to DOC production and utilization and DOC transport processes in annular wetland soil-water solutions. The concentrations of total organic carbon (TOC), total carbon (TC) and Fe(II), DOC mobility and continuous vertical and lateral flow affected the distribution variations of DOC in soil-water solutions. The correlation coefficients between DOC concentrations and TOC, TC and Fe(II) were 0.974, 0.813 and 0.753 respectively. These distribution characteristics suggested a systematic response of the distribution variations of DOC in annular wetland soil-water solutions to the geometry of closed depressions on a scale of small catchments. However, the DOC in soil pore water of the annular wetland may be the potential source of DOC to stream flow on watershed scale. These observations also implied the fragmentation of wetland landscape could bring the spatial-temporal variations of DOC distribution and exports, which would bring negative environmental impacts in watersheds of the Sanjiang Plain.

Long stroke jar bumper sub with safety sleeve

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

Downen, J.L.; Sutliff, W.N.

1981-04-14

A hydraulic jar apparatus to be disposed in a drilling string embodying inner and outer telescopically arranged elements. Overlapping portions of the elements provide an annual chamber confining an operating liquid by an annular seal fixed to the outer element at the lower end of the chamber and an annular polly pack seal fixed to the outer element at the upper end of the chamber. A piston is extended radially from the inner element into the chamber and the chamber is divided by a cylinder on the outer element into low and high pressure sections. Impact shoulders are provided onmore » the elements in axially opposed relation to produce a jarring blow and the elements are telescopically coupled by a hexagonal spline sub assembly.« less

Performance of an asymmetric short annular diffuser with a nondiverging inner wall using suction. [control of radial profiles of diffuser exit velocity

NASA Technical Reports Server (NTRS)

Juhasz, A.

1974-01-01

The performance of a short highly asymmetric annular diffuser equipped with wall bleed (suction) capability was evaluated at nominal inlet Mach numbers of 0.188, 0.264, and 0.324 with the inlet pressure and temperature at near ambient values. The diffuser had an area ratio of 2.75 and a length- to inlet-height ratio of 1.6. Results show that the radial profiles of diffuser exit velocity could be controlled from a severely hub peaked to a slightly tip biased form by selective use of bleed. At the same time, other performance parameters were also improved. These results indicate the possible application of the diffuser bleed technique to control flow profiles to gas turbine combustors.

Method and apparatus for continuous annular electrochromatography

DOEpatents

Scott, Charles D.

1987-01-01

Separation of complex mixtures and solutions can be carried out using a method and apparatus for continuous annular electrochromatography. Solutes are diverted radially by an imposed electrical field as they move downward in a rotating chromatographic column.

The Annular Suspension and Pointing (ASP) system for space experiments and predicted pointing accuracies

NASA Technical Reports Server (NTRS)

Anderson, W. W.; Joshi, S. M.

1975-01-01

An annular suspension and pointing system consisting of pointing assemblies for coarse and vernier pointing is described. The first assembly is attached to a carrier spacecraft (e.g., the space shuttle) and consists of an azimuth gimbal and an elevation gimbal which provide 'coarse' pointing. The second or vernier pointing assembly is made up of magnetic actuators of suspension and fine pointing, roll motor segments, and an instrument or experiment mounting plate around which is attached a continuous annular rim similar to that used in the annular momentum control device. The rim provides appropriate magnetic circuits for the actuators and the roll motor segments for any instrument roll position. The results of a study to determine the pointing accuracy of the system in the presence of crew motion disturbances are presented. Typical 3 sigma worst-case errors are found to be of the order of 0.001 arc-second.

Hybrid multiphase CFD simulation for liquid-liquid interfacial area prediction in annular centrifugal contactors

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

Wardle, K.E.

2013-07-01

Liquid-liquid contacting equipment used in solvent extraction processes has the dual purpose of mixing and separating two immiscible fluids. Consequently, such devices inherently encompass a wide variety of multiphase flow regimes. A hybrid multiphase computational fluid dynamics (CFD) solver which combines the Eulerian multi-fluid method with VOF (volume of fluid) sharp interface capturing has been developed for application to annular centrifugal contactors. This solver has been extended to enable prediction of mean droplet size and liquid-liquid interfacial area through a single moment population balance method. Simulations of liquid-liquid mixing in a simplified geometry and a model annular centrifugal contactor aremore » reported with droplet breakup/coalescence models being calibrated versus available experimental data. Quantitative comparison is made for two different housing vane geometries and it is found that the predicted droplet size is significantly smaller for vane geometries which result in higher annular liquid holdup.« less

Microwave generator

DOEpatents

Kwan, T.J.T.; Snell, C.M.

1987-03-31

A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit there through effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators. 6 figs.

Assembly for directing combustion gas

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

Charron, Richard C.; Little, David A.; Snyder, Gary D.

2016-04-12

An arrangement is provided for delivering gases from a plurality of combustors of a can-annular gas turbine combustion engine to a first row of turbine blades including a first row of turbine blades. The arrangement includes a gas path cylinder, a cone and an integrated exit piece (IEP) for each combustor. Each IEP comprises an inlet chamber for receiving a gas flow from a respective combustor, and includes a connection segment. The IEPs are connected together to define an annular chamber extending circumferentially and concentric to an engine longitudinal axis, for delivering the gas flow to the first row ofmore » blades. A radiused joint extends radially inward from a radially outer side of the inlet chamber to an outer boundary of the annular chamber, and a flared fillet extends radially inward from a radially inner side of the inlet chamber to an inner boundary of the annular chamber.« less

Gas turbine engine combustor can with trapped vortex cavity

DOEpatents

Burrus, David Louis; Joshi, Narendra Digamber; Haynes, Joel Meier; Feitelberg, Alan S.

2005-10-04

A gas turbine engine combustor can downstream of a pre-mixer has a pre-mixer flowpath therein and circumferentially spaced apart swirling vanes disposed across the pre-mixer flowpath. A primary fuel injector is positioned for injecting fuel into the pre-mixer flowpath. A combustion chamber surrounded by an annular combustor liner disposed in supply flow communication with the pre-mixer. An annular trapped dual vortex cavity located at an upstream end of the combustor liner is defined between an annular aft wall, an annular forward wall, and a circular radially outer wall formed therebetween. A cavity opening at a radially inner end of the cavity is spaced apart from the radially outer wall. Air injection first holes are disposed through the forward wall and air injection second holes are disposed through the aft wall. Fuel injection holes are disposed through at least one of the forward and aft walls.

Annular feed air breathing fuel cell stack

DOEpatents

Wilson, Mahlon S.

1996-01-01

A stack of polymer electrolyte fuel cells is formed from a plurality of unit cells where each unit cell includes fuel cell components defining a periphery and distributed along a common axis, where the fuel cell components include a polymer electrolyte membrane, an anode and a cathode contacting opposite sides of the membrane, and fuel and oxygen flow fields contacting the anode and the cathode, respectively, wherein the components define an annular region therethrough along the axis. A fuel distribution manifold within the annular region is connected to deliver fuel to the fuel flow field in each of the unit cells. In a particular embodiment, a single bolt through the annular region clamps the unit cells together. In another embodiment, separator plates between individual unit cells have an extended radial dimension to function as cooling fins for maintaining the operating temperature of the fuel cell stack.

The critical pressure drop for the purge process in the anode of a fuel cell

NASA Astrophysics Data System (ADS)

Yu, Xiao; Pingwen, Ming; Ming, Hou; Baolian, Yi; Shao, Zhi-Gang

Purge operation is an effective way to remove the accumulated liquid water in the anode of proton exchange membrane fuel cells (PEMFCs). This paper studies the phenomenon of the two-phase flow as well as the pressure drop fluctuation inside the flow field of a single cell during the purge process. The flow patterns are identified as intermittent purge and annular purge, and the two purge processes are contrastively analyzed and discussed. The intermittent purge greatly affects the fuel cell performance and thus it is not suitable for the in situ application. The annular purge process requires a higher pressure drop, and the critical pressure drop is calculated from the annular purge model. Furthermore, this value is quantitatively analyzed and validated by experiments. The results show that the annular purge is appropriate for removing liquid water out of the anode in the fuel cell.

Nonparaxial propagation and focusing properties of azimuthal-variant vector fields diffracted by an annular aperture.

PubMed

Gu, Bing; Xu, Danfeng; Pan, Yang; Cui, Yiping

2014-07-01

Based on the vectorial Rayleigh-Sommerfeld integrals, the analytical expressions for azimuthal-variant vector fields diffracted by an annular aperture are presented. This helps us to investigate the propagation behaviors and the focusing properties of apertured azimuthal-variant vector fields under nonparaxial and paraxial approximations. The diffraction by a circular aperture, a circular disk, or propagation in free space can be treated as special cases of this general result. Simulation results show that the transverse intensity, longitudinal intensity, and far-field divergence angle of nonparaxially apertured azimuthal-variant vector fields depend strongly on the azimuthal index, the outer truncation parameter and the inner truncation parameter of the annular aperture, as well as the ratio of the waist width to the wavelength. Moreover, the multiple-ring-structured intensity pattern of the focused azimuthal-variant vector field, which originates from the diffraction effect caused by an annular aperture, is experimentally demonstrated.

Two-phase flow patterns of a top heat mode closed loop oscillating heat pipe with check valves (THMCLOHP/CV)

NASA Astrophysics Data System (ADS)

Thongdaeng, S.; Bubphachot, B.; Rittidech, S.

2016-11-01

This research is aimed at studying the two-phase flow pattern of a top heat mode closed loop oscillating heat pipe with check valves. The working fluids used are ethanol and R141b and R11 coolants with a filling ratio of 50% of the total volume. It is found that the maximum heat flux occurs for the R11 coolant used as the working fluid in the case with the inner diameter of 1.8 mm, inclination angle of -90°, evaporator temperature of 125°C, and evaporator length of 50 mm. The internal flow patterns are found to be slug flow/disperse bubble flow/annular flow, slug flow/disperse bubble flow/churn flow, slug flow/bubble flow/annular flow, slug flow/disperse bubble flow, bubble flow/annular flow, and slug flow/annular flow.

Data transmission element for downhole drilling components

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron; Briscoe, Michael

2006-01-31

A robust data transmission element for transmitting information between downhole components, such as sections of drill pipe, in the presence of hostile environmental conditions, such as heat, dirt, rocks, mud, fluids, lubricants, and the like. The data transmission element components include a generally U-shaped annular housing, a generally U-shaped magnetically conductive, electrically insulating element such as ferrite, and an insulated conductor. Features on the magnetically conducting, electrically insulating element and the annular housing create a pocket when assembled. The data transmission element is filled with a polymer to retain the components within the annular housing by filling the pocket with the polymer. The polymer can bond with the annular housing and the insulated conductor but preferably not the magnetically conductive, electrically insulating element. A data transmission element is mounted within a recess proximate a mating surface of a downhole drilling component, such as a section of drill pipe.

Temperature and volume estimation of under-seafloor fluid from the logging-while-drilling data beneath an active hydrothermal field

NASA Astrophysics Data System (ADS)

Hamada, Y.; Saito, S.; Sanada, Y.; Masaki, Y.; Moe, K.; Kido, Y. N.; Kumagai, H.; Takai, K.; Suzuki, K.

2015-12-01

In July of 2014, offshore drillings on Iheya-North Knoll, Okinawa Trough, was executed as part of Next-generation technology for ocean resources survey, which is a research program in Cross-ministerial Strategic Innovation Promotion Program (SIP). In this expedition, logging-while- drilling (LWD) and measuring-while-drilling (MWD) were inserted into 6 holes (C9011 - C9016) to investigate spatial distribution of hydrothermal deposit and geothermal fluid reservoir. Both of these tools included annular pressure-while-drilling (APWD). Annular pressure and temperature were monitored by the APWD to detect possible exceedingly-high-temperature geofluid. In addition, drilling fluid was continuously circulated at sufficient flow rate to protect LWD tools against high temperature (non-stop driller system). At C9012 and C9016, the LWD tool clearly detected pressure and temperature anomaly at 234 meter below the seafloor (mbsf) and 80 mbsf, respectively. Annular pressure and temperature quickly increases at that depth and it would reflect the injection of high-temperature fluid. During the drilling, however, drilling water was continuously circulated at high flow-rate (2600L/min) and the measured temperature is not exactly in-situ temperature. To investigate the detail of the heat source, such as in-situ temperature and quantity of heat, we performed numerical analyses of thermal fluid and energy-balance assuming injection of high-temperature fluid. We combined pressure loss theory of double cylinders and temperature equation to replicate the fluid flow and its temperature between borehole wall and drilling pipe during the thermofluid injection. As the result, we estimated the temperature and the volume of injected fluid to be 115oC~ and 17.3 m3, respectively (at C9012) from the calculation. This temperature is lower than that of a hydrothermall vent which had been found near the hole (300oC).

High power microwave generator

DOEpatents

Ekdahl, Carl A.

1986-01-01

A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

High power microwave generator

DOEpatents

Ekdahl, C.A.

1983-12-29

A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

31 CFR 540.306 - Highly Enriched Uranium (HEU).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Highly Enriched Uranium (HEU). 540.306... OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly enriched...

31 CFR 540.306 - Highly Enriched Uranium (HEU).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Highly Enriched Uranium (HEU). 540.306... OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly enriched...

31 CFR 540.306 - Highly Enriched Uranium (HEU).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Highly Enriched Uranium (HEU). 540.306... OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly enriched...

31 CFR 540.306 - Highly Enriched Uranium (HEU).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Highly Enriched Uranium (HEU). 540.306... OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly enriched...

Simultaneous in- and out-of-plane Mitral Valve Annular Force Measurements.

PubMed

Skov, Søren N; Røpcke, Diana M; Telling, Kristine; Ilkjær, Christine; Tjørnild, Marcell J; Nygaard, Hans; Nielsen, Sten L; Jensen, Morten O

2015-06-01

Mitral valve repair with annuloplasty is often favoured over total valve replacement. In order to develop and optimize new annuloplasty ring designs, it is important to study the complex biomechanical behaviour of the valve annulus and the subvalvular apparatus with simultaneous in- and out-of-plane restraining force measurements. A new flat D-shaped mitral valve annular force transducer was developed. The transducer was mounted with strain gauges to measure strain and calibrated to provide simultaneous restraining forces in- and out of the mitral annular plane. The force transducer was implanted and evaluated in an 80 kg porcine experimental model. Accumulation of out-of-plane restraining forces, creating strain in the anterior segment were 0.7 ± 0.0 N (towards apex) and an average force accumulation of 1.5 ± 0.3 N, creating strain in the commissural segments (away from apex). The accumulations of in-plane restraining forces, creating strain on the inner side of the ring were 1.7 ± 0.2 N (away from ring center). A new mitral annular force transducer was successfully developed and evaluated in vivo. The transducer was able to measure forces simultaneously in different planes. Initial indications point towards overall agreement with previous individual force measurements in- and out-of the mitral annular plane. This can provide more detailed insight into the annular force distribution, and could potentially improve the level of evidence based mitral valve repair and support the development of future mitral annuloplasty devices.

[Multiple cephalic deep granuloma annulare of children].

PubMed

Bulinckx, A; Cambier, N; Wayllace Gaspar, L; Théate, I; Roquet-Gravy, P P; Bessis, D

2017-10-01

Deep granuloma annulare is a fairly rare variety of granuloma annulare. It is seen predominantly in children and mainly affects the anterior aspect of the legs and the top of the feet; cephalic presentation is rare. Below, we report three cases of deep granuloma annulare in children presenting solely at the cephalic extremity. Case 1: a six-year-old boy presented 7 cutaneous nodules measuring 1 to 2cm that were flesh-coloured, insensitive to palpation, of hard consistency and deeply attached. The lesions were grouped together on the anterior half of the left temporal fossa. While spontaneous regression of the three nodules was noted in the month following cutaneous biopsy, these nodules recurred a few months later. Case 2: a four-year-old girl with five deep cephalic nodules measuring around one centimetre and the colour of normal skin were seen on her right temporal fossa. The child was lost to follow-up after biopsy. Case 3: a four-month-old infant was presenting some 15 deep cutaneous nodules arranged in linear fashion on the forehead next to the left temporal fossa. These nodules regressed spontaneously one month after biopsy. In all three cases, histological examination confirmed the diagnosis of deep granuloma annulare. There have been few published cases of multiple, cephalic, deep granuloma annulare at a single site in children. The condition has an extensive differential diagnosis that includes malignant tumours; in addition, histological confirmation is normally essential. Treatment is not qualified and therapeutic extension with clinical monitoring alone may frequently be recommended. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Mitral Annular Dynamics in Mitral Annular Calcification: A Three-Dimensional Imaging Study.

PubMed

Pressman, Gregg S; Movva, Rajesh; Topilsky, Yan; Clavel, Marie-Annick; Saldanha, Jason A; Watanabe, Nozomi; Enriquez-Sarano, Maurice

2015-07-01

The mitral annulus displays complex conformational changes during the cardiac cycle that can now be quantified by three-dimensional echocardiography. Mitral annular calcification (MAC) is increasingly encountered, but its structural and dynamic consequences are largely unexplored. The objective of this study was to describe alterations in mitral annular dimensions and dynamics in patients with MAC. Transthoracic three-dimensional echocardiography was performed in 43 subjects with MAC and 36 age- and sex-matched normal control subjects. Mitral annular dimensions were quantified, using dedicated software, at six time points (three diastolic, three systolic) during the cardiac cycle. In diastole, the calcified annulus was larger and flatter than normal, with increased anteroposterior diameter (29.4 ± 0.6 vs 27.8 ± 0.6 mm, P = .046), reduced height (2.8 ± 0.2 vs 3.6 ± 0.2 mm, P = .006), and decreased saddle shape (8.9 ± 0.6% vs 11.4 ± 0.6%, P = .005). In systole, patients with MAC had greater annular area at all time points (P < .05 for each) compared with control subjects, because of reduced contraction along the anteroposterior diameter (P < .001). Saddle shape increased in early systole (from 10.5% to 13.5%, P = .04) in control subjects but not in those with MAC (P = NS). Valvular alterations were also noted; although mitral valve tent length decreased during systole in both groups, decreases were less in patients with MAC (P < .05 for mid- and late systole). For certain parameters (e.g., annular area), changes were confined largely to those patients with moderate to severe MAC (P = .006 vs control subjects, but nonsignificant for patients with mild MAC). Quantitative three-dimensional echocardiography provides new insights into the dynamic consequences of MAC. This imaging technique demonstrates that the mitral annulus is not made smaller by calcification. However, there is loss of annular contraction, particularly along the anteroposterior diameter, and loss of early systolic folding along the intercommissural diameter. Associated valvular alterations include smaller than usual declines in tenting during systole. These quantitative three-dimensional echocardiographic data provide new insights into the dynamic physiology of the calcified mitral annulus. Copyright © 2015 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Injector design for liner-on-target gas-puff experiments

NASA Astrophysics Data System (ADS)

Valenzuela, J. C.; Krasheninnikov, I.; Conti, F.; Wessel, F.; Fadeev, V.; Narkis, J.; Ross, M. P.; Rahman, H. U.; Ruskov, E.; Beg, F. N.

2017-11-01

We present the design of a gas-puff injector for liner-on-target experiments. The injector is composed of an annular high atomic number (e.g., Ar and Kr) gas and an on-axis plasma gun that delivers an ionized deuterium target. The annular supersonic nozzle injector has been studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated (M > 5), ˜1 cm radius gas profile that satisfies the theoretical requirement for best performance on ˜1-MA current generators. The CFD simulations allowed us to study output density profiles as a function of the nozzle shape, gas pressure, and gas composition. We have performed line-integrated density measurements using a continuous wave (CW) He-Ne laser to characterize the liner gas density. The measurements agree well with the CFD values. We have used a simple snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector.

Injector design for liner-on-target gas-puff experiments.

PubMed

Valenzuela, J C; Krasheninnikov, I; Conti, F; Wessel, F; Fadeev, V; Narkis, J; Ross, M P; Rahman, H U; Ruskov, E; Beg, F N

2017-11-01

We present the design of a gas-puff injector for liner-on-target experiments. The injector is composed of an annular high atomic number (e.g., Ar and Kr) gas and an on-axis plasma gun that delivers an ionized deuterium target. The annular supersonic nozzle injector has been studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated (M > 5), ∼1 cm radius gas profile that satisfies the theoretical requirement for best performance on ∼1-MA current generators. The CFD simulations allowed us to study output density profiles as a function of the nozzle shape, gas pressure, and gas composition. We have performed line-integrated density measurements using a continuous wave (CW) He-Ne laser to characterize the liner gas density. The measurements agree well with the CFD values. We have used a simple snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector.

Multi-point optimization of recirculation flow type casing treatment in centrifugal compressors

NASA Astrophysics Data System (ADS)

Tun, Min Thaw; Sakaguchi, Daisaku

2016-06-01

High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines. A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors. Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS. The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range. Sensitivity analysis of design parameters as a function of efficiency has been performed. It is found that the optimized casing design provides optimized recirculation flow rate, in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.

Optical coating design for the annular mirrors of the Alpha I HF laser

NASA Astrophysics Data System (ADS)

Shellan, Jeffrey B.

The dielectric-coating design for the annular mirrors of the Alpha I HF laser is described along with the numerous other designs that were considered. The coatings were required to produce a 0-deg phase shift after one round trip, which involved reflections from six surfaces. Although novel high-reflectivity multilayer dielectric coatings satisfied this requirement, single-layer phase control coatings were preferred because the use of these greatly reduced coating layer-thickness control and thus resulted in significant program savings. Among the single-layer designs investigated, a coating consisting of a 0.06-micron-thick SiO layer was found to be sufficient for all surfaces except those of the rear cone, for which a 0.515-micron thick SiO layer was recommended. The metallic substrate selected was Au. These coatings were found to have a high damage threshold, provide the necessary polarization phase control, and to be quite forgiving to thickness deposition errors that were anticipated using existing chambers.

Study on surface roughness evolvement of Nd-doped phosphate glass after IBF

NASA Astrophysics Data System (ADS)

Li, Furen; Xie, Xuhui; Zhou, Lin; Tie, Guipeng; Hu, Hao

2016-10-01

Nd doped phosphate glass is widely used as gain media in high power laser system. It is traditionally polished with the annular polishing technology. The edge effect is inevitable in annular polishing process and it results in the low manufacturing efficiency. Ion Beam Figuring (IBF) is a highly deterministic, non-contact method for the ultra-precision optics fabrication. So the edge effect is avoided. Nanometer and sub-nanometer precision is realizable in IBF. In this paper, Nd doped phosphate glass was polished with IBF, and the evolvement of surface roughness was emphasized. The roughness of surface polished with ion beam at normal and oblique incidence was researched. The oblique incident angle was 45°. The surface roughness was measured with the white light interferometer. No evident change was observed. This means that the pre-finish roughness can be preserved in IBF. The results denote that IBF is a feasible method to correct the contour errors of Nd doped phosphate glass, and the roughness will not be coarsened.

Optical Diagnosis of Gas Turbine Combustors Being Conducted

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Locke, Randy J.; Anderson, Robert C.; DeGroot, Wilhelmus A.

2001-01-01

Researchers at the NASA Glenn Research Center, in collaboration with industry, are reducing gas turbine engine emissions by studying visually the air-fuel interactions and combustion processes in combustors. This is especially critical for next generation engines that, in order to be more fuel-efficient, operate at higher temperatures and pressures than the current fleet engines. Optically based experiments were conducted in support of the Ultra-Efficient Engine Technology program in Glenn's unique, world-class, advanced subsonic combustion rig (ASCR) facility. The ASCR can supply air and jet fuel at the flow rates, temperatures, and pressures that simulate the conditions expected in the combustors of high-performance, civilian aircraft engines. In addition, this facility is large enough to support true sectors ("pie" slices of a full annular combustor). Sectors enable one to test true shapes rather than rectangular approximations of the actual hardware. Therefore, there is no compromise to actual engine geometry. A schematic drawing of the sector test stand is shown. The test hardware is mounted just upstream of the instrumentation section. The test stand can accommodate hardware up to 0.76-m diameter by 1.2-m long; thus sectors or small full annular combustors can be examined in this facility. Planar (two-dimensional) imaging using laser-induced fluorescence and Mie scattering, chemiluminescence, and video imagery were obtained for a variety of engine cycle conditions. The hardware tested was a double annular sector (two adjacent fuel injectors aligned radially) representing approximately 15 of a full annular combustor. An example of the two-dimensional data obtained for this configuration is also shown. The fluorescence data show the location of fuel and hydroxyl radical (OH) along the centerline of the fuel injectors. The chemiluminescence data show C2 within the total observable volume. The top row of this figure shows images obtained at an engine low-power condition, and the bottom row shows data from a higher power operating point. The data show distinctly the differences in flame structure between low-power and high-power engine conditions, in both location and amount of species produced (OH, C2) or consumed (fuel). The unique capability of the facility coupled with its optical accessibility helps to eliminate the need for high-pressure performance extrapolations. Tests such as described here have been used successfully to assess the performance of fuel-injection concepts and to modify those designs, if needed.

Theoretical characterization of annular array as a volumetric optoacoustic ultrasound handheld probe

NASA Astrophysics Data System (ADS)

Kalkhoran, Mohammad Azizian; Vray, Didier

2018-02-01

Optoacoustic ultrasound (OPUS) is a promising hybridized technique for simultaneous acquisition of functional and morphological data. The optical specificity of optoacoustic leverages the diagnostic aptitude of ultrasonography beyond anatomy. However, this integration has been rarely practiced for volumetric imaging. The challenge lies in the effective imaging probes that preserve the functionality of both modalities. The potentials of a sparse annular array for volumetric OPUS imaging are theoretically investigated. In order to evaluate and optimize the performance characteristics of the probe, series of analysis in the framework of system model matrix was carried out. The two criteria of voxel crosstalk and eigenanalysis have been employed to unveil information about the spatial sensitivity, aliasing, and number of definable spatial frequency components. Based on these benchmarks, the optimal parameters for volumetric handheld probe are determined. In particular, the number, size, and the arrangement of the elements and overall aperture dimension were investigated. The result of the numerical simulation suggests that the segmented-annular array of 128 negatively focused elements with 1λ × 20λ size, operating at 5-MHz central frequency showcases a good agreement with the physical requirement of both imaging systems. We hypothesize that these features enable a high-throughput volumetric passive/active ultrasonic imaging system with great potential for clinical applications.

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

Hayes, S. L.; Harp, J. M.; Chichester, H. J. M.

Research and development activities on metallic fuels in the US are focused on their potential use for actinide transmutation in future sodium fast reactors. As part of this application, there is a desire to demonstrate a multifold increase in burnup potential. A number of metallic fuel design innovations are under investigation with a view toward significantly increasing the burnup potential of metallic fuels, since higher discharge burnups equate to lower potential actinide losses during recycle. Promising innovations under investigation include: 1) lowering the fuel smeared density in order to accommodate the additional swelling expected as burnups increase, 2) utilizing anmore » annular fuel geometry for better geometrical stability at low smeared densities, as well as the potential to eliminate the need for a sodium bond, and 3) minor alloy additions to immobilize lanthanide fission products inside the metallic fuel matrix and prevent their transport to the cladding resulting in fuel-cladding chemical interaction. This paper presents results from these efforts to advance metallic fuel technology in support of high burnup and actinide transmutation objectives. Highlights include examples of fabrication of low smeared density annular metallic fuels, experiments to identify alloy additions effective in immobilizing lanthanide fission products, and early postirradiation examinations of annular metallic fuels having low smeared densities and palladium additions for fission product immobilization.« less

Azimuthally spinning wave modes and heat release in an annular combustor

NASA Astrophysics Data System (ADS)

Nygard, Hakon; Mazur, Marek; Dawson, James R.; Worth, Nicholas A.

2017-11-01

In order to reduce NOx emissions from aeroengines and stationary gas turbines the fuel-air mixture can be made leaner, at the risk of introducing potentially damaging thermo-acoustic instabilities. At present this phenomenon is not understood well enough to eliminate these instabilities at the design stage. Recently, the presence of different azimuthal modes in annular combustors has been demonstrated both experimentally and numerically. These naturally occurring instabilities in annular geometry have been observed to constantly switch between spinning and standing modes, making it more difficult to analyse the flame structure and dynamics. Very recently this issue was partially addressed using novel acoustic forcing to generate a standing mode. In the present study this concept has been developed further by creating an azimuthal array of loud speakers, which for the first time permits predominantly spinning modes to be set up inside the combustion chamber. The use of pressure and high speed OH* measurements enables the study of the flame dynamics and heat release rate oscillations of the combustor, which will be reported in the current paper. The ability to precisely control the azimuthal mode of oscillation greatly enhances our further understanding of the phenomenon. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No 677931 TAIAC).

Non-null annular subaperture stitching interferometry for aspheric test

NASA Astrophysics Data System (ADS)

Zhang, Lei; Liu, Dong; Shi, Tu; Yang, Yongying; Chong, Shiyao; Miao, Liang; Huang, Wei; Shen, Yibing; Bai, Jian

2015-10-01

A non-null annular subaperture stitching interferometry (NASSI), combining the subaperture stitching idea and non-null test method, is proposed for steep aspheric testing. Compared with standard annular subaperture stitching interferometry (ASSI), a partial null lens (PNL) is employed as an alternative to the transmission sphere, to generate different aspherical wavefronts as the references. The coverage subaperture number would thus be reduced greatly for the better performance of aspherical wavefronts in matching the local slope of aspheric surfaces. Instead of various mathematical stitching algorithms, a simultaneous reverse optimizing reconstruction (SROR) method based on system modeling and ray tracing is proposed for full aperture figure error reconstruction. All the subaperture measurements are simulated simultaneously with a multi-configuration model in a ray-tracing program, including the interferometric system modeling and subaperture misalignments modeling. With the multi-configuration model, full aperture figure error would be extracted in form of Zernike polynomials from subapertures wavefront data by the SROR method. This method concurrently accomplishes subaperture retrace error and misalignment correction, requiring neither complex mathematical algorithms nor subaperture overlaps. A numerical simulation exhibits the comparison of the performance of the NASSI and standard ASSI, which demonstrates the high accuracy of the NASSI in testing steep aspheric. Experimental results of NASSI are shown to be in good agreement with that of Zygo® VerifireTM Asphere interferometer.

Study on power coupling of annular vortex beam propagating through a two-Cassegrain-telescope optical system in turbulent atmosphere.

PubMed

Wu, Huiyun; Sheng, Shen; Huang, Zhisong; Zhao, Siqing; Wang, Hua; Sun, Zhenhai; Xu, Xiegu

2013-02-25

As a new attractive application of the vortex beams, power coupling of annular vortex beam propagating through a two- Cassegrain-telescope optical system in turbulent atmosphere has been investigated. A typical model of annular vortex beam propagating through a two-Cassegrain-telescope optical system is established, the general analytical expression of vortex beams with limited apertures and the analytical formulas for the average intensity distribution at the receiver plane are derived. Under the H-V 5/7 turbulence model, the average intensity distribution at the receiver plane and power coupling efficiency of the optical system are numerically calculated, and the influences of the optical topological charge, the laser wavelength, the propagation path and the receiver apertures on the power coupling efficiency are analyzed. These studies reveal that the average intensity distribution at the receiver plane presents a central dark hollow profile, which is suitable for power coupling by the Cassegrain telescope receiver. In the optical system with optimized parameters, power coupling efficiency can keep in high values with the increase of the propagation distance. Under the atmospheric turbulent conditions, great advantages of vortex beam in power coupling of the two-Cassegrain-telescope optical system are shown in comparison with beam without vortex.

Portal annular pancreas: a systematic review of a clinical challenge.

PubMed

Harnoss, Jonathan M; Harnoss, Julian C; Diener, Markus K; Contin, Pietro; Ulrich, Alexis B; Büchler, Markus W; Schmitz-Winnenthal, Friedrich H

2014-10-01

Portal annular pancreas (PAP) is an asymptomatic congenital pancreas anomaly, in which portal and/or mesenteric veins are encased by pancreas tissue. The aim of the study was to determine the role of PAP in pancreatic surgery as well as its management and potential complication, specifically, postoperative pancreatic fistula (POPF).On the basis of a case report, the MEDLINE and ISI Web of Science databases were systematically reviewed up to September 2012. All articles describing a case of PAP were considered.In summary, 21 studies with 59 cases were included. The overall prevalence of PAP was 2.4% and the patients' mean (SD) age was 55.9 (16.2) years. The POPF rate in patients with PAP (12 pancreaticoduodenectomies and 3 distal pancreatectomies) was 46.7% (in accordance with the definition of the International Study Group of Pancreatic Surgery).Portal annular pancreas is a quite unattended pancreatic variant with high prevalence and therefore still remains a clinical challenge to avoid postoperative complications. To decrease the risk for POPF, attentive preoperative diagnostics should also focus on PAP. In pancreaticoduodenectomy, a shift of the resection plane to the pancreas tail should be considered; in extensive pancreatectomy, coverage of the pancreatic remnant by the falciform ligament could be a treatment option.

The Growth of Instabilities in Annular Liquid Sheets

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

Duke, Daniel J.; Honnery, Damon R; Soria, Julio

An annular liquid sheet surrounded by parallel co-flowing gas is an effective atomiser. However, the initial instabilities which determine the primary break-up of the liquid sheet are not well understood. Lack of agreement on the influence of the boundary conditions and the non-dimension scaling of the initial instability persists between theoretical stability analyses and experiments. To address this matter, we have undertaken an experimental parametric study of an aerodynamically-driven, non-swirling annular water sheet. The effects of sheet thickness, inner and outer gas-liquid momentum ratio were investigated over an order of magnitude variation in Reynolds and Weber number. From high-speed imagemore » correlation measurements in the near-nozzle region, we propose new empirical correlations for the frequency of the instability as a function of the total gas-liquid momentum ratio, with good non-dimensional collapse. From analysis of the instability velocity probability densities, we find two persistent and distinct superimposed instabilities with different growth rates. The first is a short-lived, rapidly saturating sawtooth-like instability. The second is a slower-growing stochastic instability which persists through the break-up of the sheet. The presence of multiple instabilities whose growth rates do not strongly correlate with the shear velocities may explain some of the discrepancies between experiments and stability analyses.« less

Obseration of flow regime transition in CFB riser using an LDV

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

Yue, Paul C.; Mei, Joseph S.; Shadle, Lawrence J.

2011-01-01

The solids flow in a circulating fluidized bed (CFB) riser is often described to have a core-annular structure. For a given superficial gas velocity, at the initial introduction of solids into a riser a flow structure of dilute upflow regime exists. Continuing to increase the solids flow in the riser transitions the flow structure to the core-annular flow regime. However, with further increase of solids flow a condition is reached, depending on the superficial gas velocity, where all the solids across the riser cross section flow upwards, even those at the wall. When the solids flux, solids fraction and gasmore » velocity are relatively high, such a condition is described as the dense phase suspense upflow (DSU) regime. In this paper we report our observations of these flow regime transitions by using a laser Doppler velocimeter (LDV) to monitor the upward and downward particle flow velocities at and near the riser wall of the National Energy Technology Laboratory’s 30.4 centimeters diameter CFB cold flow model. The particles were high density polyethylene (PPE) spheres with a Sauter mean diameter of 861 micron and a density of 800 kg/m3. Three superficial gas velocities of 6.55 m/s, 10.67 m/s and 13.72 m/s were used in this study. For the case of superficial gas velocity 6.55 m/s, the experimental data show that the transition from dilute upflow to core-annular flow occurred when the solids flux was about 7 kg/m{sup 2}-s and the transition from core-annular flow to dense suspension upflow was about 147 kg/m{sup 2}-s. As the superficial gas velocity was increased to 10.67 m/s the corresponding flow regime transitions were at 34 kg/m{sup 2}-s and 205 kg/m{sup 2}-s, respectively. For the case of superficial gas velocity of 13.72 m/s the data showed no distinct transition of flow regimes. The particles were all upflow for the range of solids fluxes from 10 kg/m{sup 2}-s to 286 kg/m{sup 2}-s.« less

Dynamics of face and annular seals with two-phase flow

NASA Technical Reports Server (NTRS)

Hughes, William F.; Basu, Prithwish; Beatty, Paul A.; Beeler, Richard M.; Lau, Stephen

1989-01-01

A detailed study was made of face and annular seals under conditions where boiling, i.e., phase change of the leaking fluid, occurs within the seal. Many seals operate in this mode because of flashing due to pressure drop and/or heat input from frictional heating. High pressure, water pumps, industrial chemical pumps, and cryogenic pumps are mentioned as a few of many applications. The initial motivation was the LOX-GOX seals for the space shuttle main engine, but the study was expanded to include any face or annular seal where boiling occurs. Some of the distinctive behavior characteristics of two-phase seals were discussed, particularly their axial stability. While two-phase seals probably exhibit instability to disturbances of other degrees of freedom such as wobble, etc., under certain conditions, such analyses are too complex to be treated at present. Since an all liquid seal (with parallel faces) has a neutral axial stiffness curve, and is stabilized axially by convergent coning, other degrees of freedom stability analyses are necessary. However, the axial stability behavior of the two-phase seal is always a consideration no matter how well the seal is aligned and regardless of the speed. Hence, axial stability is thought of as the primary design consideration for two-phase seals and indeed the stability behavior under sub-cooling variations probably overshadows other concerns. The main thrust was the dynamic analysis of axial motion of two-phase face seals, principally the determination of axial stiffness, and the steady behavior of two-phase annular seals. The main conclusions are that seals with two-phase flow may be unstable if improperly balanced. Detailed theoretical analyses of low (laminar) and high (turbulent) leakage seals are presented along with computer codes, parametric studies, and in particular a simplified PC based code that allows for rapid performance prediction. A simplified combined computer code for the performance prediction over the laminar and turbulent ranges of a two-phase seal is described and documented. The analyses, results, and computer codes are summarized.

Cryogenically cooled detector pin mount

DOEpatents

Hunt, Jr., William E; Chrisp, Michael P

2014-06-03

A focal plane assembly facilitates a molybdenum base plate being mounted to another plate made from aluminum. The molybdenum pin is an interference fit (press fit) in the aluminum base plate. An annular cut out area in the base plate forms two annular flexures.

Theory versus experiment for the rotordynamic coefficients of annular gas seals. I - Test facility and apparatus

NASA Technical Reports Server (NTRS)

Childs, D. W.; Nelson, C. E.; Nicks, C.; Scharrer, J.; Elrod, D.

1985-01-01

A facility and apparatus are described for determining the rotordynamic coefficients and leakage characteristics of annular gas seals. The coefficients and leakage characteristics of annular gas seals. The apparatus has a current top speed of 8000 cpm with a nominal seal diameter of 15.24 cmn (6 in.). The air supply unit yields a seal pressure ratio of approximately 7. An external shaker is used to excite the test rotor. The capability to independently calculate all rotordynamic coefficients at a given operating condition with one excitation frequency are discussed.

Removal of atmospheric oxidants with annular denuders

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

Williams, E.L. II; Grosjean, D.

1990-06-01

Annular denuders have been tested for their ability to remove atmospheric photochemical oxidants including ozone (150-170 ppb), nitrogen dioxide (40-200 ppb), nitric acid (35 ppb), and peroxyacetyl nitrate (PAN, 6-25 ppb). Formaldehyde (80-140 ppb) was also tested as a copollutant. Tests were carried out at low rates of 1,2, and 20 L/min, with oxidants tested singly or as part of photochemical mixtures in purified air. Efficient collection was obtained with annular denuders coated with potassium iodide (O{sub 3}), phenoxamine (O{sub 3}), sodium carbonate (HNO{sub 3}), potassium hydroxide (PAN), and 2,4-dinitrophenylhydrazine (HCHO).

Concentric Coplanar Capacitive Sensor System with Quantitative Model

NASA Technical Reports Server (NTRS)

Chen, Tianming (Inventor); Bowler, Nicola (Inventor)

2014-01-01

A concentric coplanar capacitive sensor includes a charged central disc forming a first electrode, an outer annular ring coplanar with and outer to the charged central disc, the outer annular ring forming a second electrode, and a gap between the charged central disc and the outer annular ring. The first electrode and the second electrode may be attached to an insulative film. A method provides for determining transcapacitance between the first electrode and the second electrode and using the transcapacitance in a model that accounts for a dielectric test piece to determine inversely the properties of the dielectric test piece.

Device for coupling a first vehicle to a second vehicle

NASA Technical Reports Server (NTRS)

Rudmann, A. A. (Inventor)

1980-01-01

A device is disclosed, carried by a first vehicle such as an orbiting space shuttle, having a plurality of contact members for engaging and holding an annular ring on a second vehicle such as an orbiting payload. The contact members are connected to manipulator arms which are mounted at a fulcrum point and which are moved by an iris type mechanism. Movement of the manipulator arms causes the contact members to grasp or release the annular ring. Bumper devices are provided to axially align the annular ring and draw the contact members into engagement therewith.

Production and delivery of a fluid mixture to an annular volume of a wellbore

DOEpatents

Hermes, Robert E [Los Alamos, NM; Bland, Ronald Gene [Houston, TX; Foley, Ron Lee [Magnolia, TX; Bloys, James B [Katy, TX; Gonzalez, Manuel E [Kingwood, NM; Daniel, John M [Germantown, TN; Robinson, Ian M [Guisborough, GB; Carpenter, Robert B [Tomball, TX

2012-01-24

The methods described herein generally relate to preparing and delivering a fluid mixture to a confined volume, specifically an annular volume located between two concentrically oriented casing strings within a hydrocarbon fluid producing well. The fluid mixtures disclosed herein are useful in controlling pressure in localized volumes. The fluid mixtures comprise at least one polymerizable monomer and at least one inhibitor. The processes and methods disclosed herein allow the fluid mixture to be stored, shipped and/or injected into localized volumes, for example, an annular volume defined by concentric well casing strings.

Production Of Hydroxylated Fatty Acids In Genetically Modified Plants

DOEpatents

Hall, David R.; Fox, Joe

2002-05-21

An annular wire harness for use in drill pipe comprising two rings interconnected by one or more insulated conductors. The rings are positioned within annular grooves located within the tool joints and the conductors are fixed within grooves along the bore wall of the pipe. The rings may be recessed within annular grooves in order to permit refacing of the tool joint. The rings are provided with means for coupling a power and data signal from an adjacent pipe to the conductors in such a fashion that the signal may be transmitted along the drill pipe and along an entire drill string.

Cold-air annular-cascade investigation of aerodynamic performance of cooled turbine vanes. 2: Trailing-edge ejection, film cooling, and transpiration cooling

NASA Technical Reports Server (NTRS)

Goldman, L. J.; Mclallin, K. L.

1975-01-01

The aerodynamic performance of four different cooled vane configurations was experimentally determined in a full-annular cascade at a primary- to coolant-total-temperature ratio of 1.0. The vanes were tested over a range of coolant flow rates and pressure ratios. Overall vane efficiencies were obtained and compared, where possible, with the results obtained in a four-vane, annular-sector cascade. The vane efficiency and exit flow conditions as functions of radial position were also determined and compared with solid (uncooled) vane results.

The reproductive strategies of the heterocarpic annual Calendula arvensis (Asteraceae)

NASA Astrophysics Data System (ADS)

Ruiz De Clavijo, E.

2005-09-01

Achene polymorphism and various aspects of the reproductive biology of the annual Calendula arvensis L. (Field marigold), were studied to determine the reproductive strategies of the plant. This species normally produces three types of achene: rostrate, cymbiform and annular. Rostrate and cymbiform achenes are larger and heavier than annular achenes, and are adapted to long-range dispersal (by epizoochory and anemochory, respectively). In contrast, annular achenes are smaller in size and weight, and are adapted to short-range dispersal. Achenes germinate over a broad range of temperatures (both in light and in darkness), exhibiting cymbiform achenes the highest germination percentages and annular achenes the lowest under all conditions tested. A fraction of the three types of achenes exhibit dormancy and presumably enter the soil seedbank. Achene types adapted for long-range dispersal (rostrate and cymbiform achenes) produce seedlings that are best able to emerge from deeper burial depths, and that are initially stronger and exhibit earlier flowering than the plants from the annular achenes (which are likely to disperse over shorter distances). These features, together with the fact that fruiting occurs even in the absence of pollinators (automatic geitonogamy), the different mechanisms for achene dispersal (zoochory, anemochory and myrmerochory), and the extended germination, flowering and fruiting periods, facilitate establishment and expansion of this species in unpredictable and disturbed habitats.

Inductive coupler for downhole components and method for making same

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Briscoe, Michael A.; Sneddon, Cameron; Fox, Joe

2006-05-09

The present invention includes a method of making an inductive coupler for downhole components. The method includes providing an annular housing, preferably made of steel, the housing having a recess. A conductor, preferably an insulated wire, is also provided along with a plurality of generally U-shaped magnetically conducting, electrically insulating (MCEI) segments. Preferably, the MCEI segments comprise ferrite. An assembly is formed by placing the plurality of MCEI segments within the recess in the annular housing. The segments are aligned to form a generally circular trough. A first portion of the conductor is placed within the circular trough. This assembly is consolidated with a meltable polymer which fills spaces between the segments, annular housing and the first portion of the conductor. The invention also includes an inductive coupler including an annular housing having a recess defined by a bottom portion and two opposing side wall portions. At least one side wall portion includes a lip extending toward but not reaching the other side wall portion. A plurality of generally U-shaped MCEI segments, preferably comprised of ferrite, are disposed in the recess and aligned so as to form a circular trough. The coupler further includes a conductor disposed within the circular trough and a polymer filling spaces between the segments, the annular housing and the conductor.

Annular denuders for use in global climate and stratospheric measurements of acidic gases and particles

NASA Technical Reports Server (NTRS)

Stevens, Robert K.

1991-01-01

Measurements of acidic and basic gases that coexist with fine particle (less than 2.5 micron) may be useful for determining the impact of these species on global climate changes and determining species that influence stratospheric ozone levels. Annular denuders are well suited for this purpose. A new concentric annular denuder system, consisting of a three channel denuder, a Teflon coated cyclone preseparator, and a multistage filter pack was developed, evaluated, and shown to provide reliable atmospheric measurements of SO2, HNO2, HNO3, NH3, SO4(=), NH4(+), NO3(-), and H(+). For example, the precision of the annular denuder for the ambient measurements of HNO3 and nitrates at concentrations between 0.1 to 3 microgram/cu m was + or - 12 and 16 pct., respectively. The 120 x 25 mm three channel denuder is encased in a stainless steel sheath and has annular spaces that are 1 mm wide. This design was shown to have nearly identical capacity for removal of SO2 as conventional 210 x 25 mm single channel denuder configurations. The cyclone preseparator was designed and tested to have a D sub 50 cutoff diameter of 2.5 micron and minimal retention of HNO3.

Shaft seal system

DOEpatents

Kapich, Davorin D.

1985-01-01

A shaft seal system is disclosed for isolating two regions of different fluid mediums through which a rotatable shaft extends. The seal system includes a seal housing through which the shaft extends and which defines an annular land and an annular labyrinth both of which face on the shaft so that each establishes a corresponding fluid sealing annulus. A collection cavity is formed in communication with the annular sealing spaces, and fluids compatible with the fluids in each of the two regions to be isolated are introduced, respectively, into the annular sealing spaces and collected in the collection cavity from which the fluid mixture is removed and passed to a separator which separates the fluids and returns them to their respective annular sealing spaces in a recycling manner. In the illustrated embodiment, the isolated fluid mediums comprise a liquid region and a gas region. Gas is removed from the gas region and passed through a purifier and a gas pump operative to introduce the purified gas through the labyrinth sealing annulus to the collection cavity. After passing to the separator, the separated gas is passed through a dryer from which the dried gas is caused to pass through the labyrinth sealing annulus into the collection cavity independently of the purified gas so as to insure isolation of the gas region in the event of sealing gas pump malfunction.

LOW-LOSS CABLE AND METHOD OF FABRICATION

DOEpatents

McCarthy, R.L. et al.

1960-09-27

A radiation-resistant coaxial electrical cable capable of carrying very small currents at high voltages with little leakage is described. The cable comprises an inner axial conductor separated from an outer coaxial tubular conductor by annular layer of fibrous silica insulation. The silica insulation is formed by leaching boron from spun horosilicate glass and then heat treating the silica at a high temperature.

Particle detection for patterned wafers of 100nm design rule by evanescent light illumination: analysis of evanescent light scattering using Finite-Difference Time-Domain (FDTD) method

NASA Astrophysics Data System (ADS)

Yoshioka, Toshie; Miyoshi, Takashi; Takaya, Yasuhiro

2005-12-01

To realize high productivity and reliability of the semiconductor, patterned wafers inspection technology to maintain high yield becomes essential in modern semiconductor manufacturing processes. As circuit feature is scaled below 100nm, the conventional imaging and light scattering methods are impossible to apply to the patterned wafers inspection technique, because of diffraction limit and lower S/N ratio. So, we propose a new particle detection method using annular evanescent light illumination. In this method, a converging annular light used as a light source is incident on a micro-hemispherical lens. When the converging angle is larger than critical angle, annular evanescent light is generated under the bottom surface of the hemispherical lens. Evanescent light is localized near by the bottom surface and decays exponentially away from the bottom surface. So, the evanescent light selectively illuminates the particles on the patterned wafer surface, because it can't illuminate the patterned wafer surface. The proposed method evaluates particles on a patterned wafer surface by detecting scattered evanescent light distribution from particles. To analyze the fundamental characteristics of the proposed method, the computer simulation was performed using FDTD method. The simulation results show that the proposed method is effective for detecting 100nm size particle on patterned wafer of 100nm lines and spaces, particularly under the condition that the evanescent light illumination with p-polarization and parallel incident to the line orientation. Finally, the experiment results suggest that 220nm size particle on patterned wafer of about 200nm lines and spaces can be detected.

Chirp-coded excitation imaging with a high-frequency ultrasound annular array.

PubMed

Mamou, Jonathan; Ketterling, Jeffrey A; Silverman, Ronald H

2008-02-01

High-frequency ultrasound (HFU, > 15 MHz) is an effective means of obtaining fine-resolution images of biological tissues for applications such as opthalmologic, dermatologic, and small animal imaging. HFU has two inherent drawbacks. First, HFU images have a limited depth of field (DOF) because of the short wavelength and the low fixed F-number of conventional HFU transducers. Second, HFU can be used to image only a few millimeters deep into a tissue because attenuation increases with frequency. In this study, a five-element annular array was used in conjunction with a synthetic-focusing algorithm to extend the DOF. The annular array had an aperture of 10 mm, a focal length of 31 mm, and a center frequency of 17 MHz. To increase penetration depth, 8-micros, chirp-coded signals were designed, input into an arbitrary waveform generator, and used to excite each array element. After data acquisition, the received signals were linearly filtered to restore axial resolution and increase the SNR. To compare the chirpcoded imaging method with conventional impulse imaging in terms of resolution, a 25-microm diameter wire was scanned and the -6-dB axial and lateral resolutions were computed at depths ranging from 20.5 to 40.5 mm. The results demonstrated that chirp-coded excitation did not degrade axial or lateral resolution. A tissue-mimicking phantom containing 10-microm glass beads was scanned, and backscattered signals were analyzed to evaluate SNR and penetration depth. Finally, ex vivo ophthalmic images were formed and chirpcoded images showed features that were not visible in conventional impulse images.

Coupling of an applied field magnetically insulated ion diode to a high power magnetically insulated transmission line system

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

Maenchen, J.E.

1983-01-01

The coupling of energy from a high power pulsed accelerator through a long triplate magnetically insulated transmission line (MITL) in vacuum to an annular applied magnetic field insulated extraction ion diode is examined. The narrow power transport window and the wave front erosion of the MITL set stringent impedance history conditions on the diode load. A new ion diode design developed to satisfy these criteria with marginal electron insulation is presented. The LION accelerator is used to provide a positive polarity 1.5 MV, 350 kA, 40 ns FWHM pulse with a 30 kA/ns current rate from a triplate MITL source.more » A transition converts the triplate into a cylindrical cross section which flares into the ion diode load. Extensive current and voltage measurements performed along this structure and on the extracted ion beam provide conclusive evidence that the self insulation condition of the MITL is maintained in the transition by current loss alone. The ion diode utilizes a radial magnetic field between a grounded cathode annular emission tip and a disk anode. A 50 cm/sup 2/ dielectric/metal anode area serves as the ion plasma source subject to direct electron bombardment from the opposing cathode tip under marginal magnetic insulation conditions. The ions extracted cross the radial magnetic field and exit the diode volume as an annular cross section beam of peak current about 100 kA. The diode current gradually converts from the initial electron flow to nearly 100% ion current af« less

Mechanisms and Predictors of Mitral Regurgitation after High-Risk Myocardial Infarction

PubMed Central

Meris, Alessandra; Amigoni, Maria; Verma, Anil; Thune, Jens Jakob; Køber, Lars; Velazquez, Eric; McMurray, John J. V.; Pfeffer, Marc A.; Califf, Robert; Levine, Robert A.; Solomon, Scott D.

2012-01-01

Background Mitral regurgitation (MR) has been associated with adverse outcomes after myocardial infarction (MI). Without structural valve disease, functional MR has been related to left ventricular (LV) remodeling and geometric deformation of the mitral apparatus. The aims of this study were to elucidate the mechanistic components of MR after high-risk MI and to identify predictors of MR progression during follow-up. Methods The Valsartan in Acute Myocardial Infarction Echo substudy prospectively enrolled 610 patients with LV dysfunction, heart failure, or both after MI. MR at baseline, 1 month, and 20 months was quantified by mapping jet expansion in the left atrium in 341 patients with good-quality echocardiograms. Indices of LV remodeling, left atrial size, and diastolic function and parameters of mitral valve deformation, including tenting area, coaptation depth, anterior leaflet concavity, annular diameters, and contractility, were assessed and related to baseline MR. The progression of MR was further analyzed, and predictors of worsening among the baseline characteristics were identified. Results Tenting area, coaptation depth, annular dilatation, and left atrial size were all associated with the degree of baseline MR. Tenting area was the only significant and independent predictor of worsening MR; a tenting area of 4 cm2 was a useful cutoff to identify worsening of MR after MI and moderate to severe MR after 20 months. Conclusions Increased mitral tenting and larger mitral annular area are determinants of MR degree at baseline, and tenting area is an independent predictor of progression of MR after MI. Although LV remodeling itself contributes to ischemic MR, this influence is directly dependent on alterations in mitral geometry. PMID:22305962

An equivalent network representation of a clamped bimorph piezoelectric micromachined ultrasonic transducer with circular and annular electrodes using matrix manipulation techniques.

PubMed

Sammoura, Firas; Smyth, Katherine; Kim, Sang-Gook

2013-09-01

An electric circuit model for a clamped circular bimorph piezoelectric micromachined ultrasonic transducer (pMUT) was developed for the first time. The pMUT consisted of two piezoelectric layers sandwiched between three thin electrodes. The top and bottom electrodes were separated into central and annular electrodes by a small gap. While the middle electrode was grounded, the central and annular electrodes were biased with two independent voltage sources. The strain mismatch between the piezoelectric layers caused the plate to vibrate and transmit a pressure wave, whereas the received echo generated electric charges resulting from plate deformation. The clamped pMUT plate was separated into a circular and an annular plate, and the respective electromechanical transformation matrices were derived. The force and velocity vectors were properly selected using Hamilton's principle and the necessary boundary conditions were invoked. The electromechanical transformation matrix for the clamped circular pMUT was deduced using simple matrix manipulation techniques. The pMUT performance under three biasing schemes was elaborated: 1) central electrode only, 2) central and annular electrodes with voltages of the same magnitude and polarity, and 3) central and annular electrodes with voltages of the same magnitude and opposite polarity. The circuit parameters of the pMUT were extracted for each biasing scheme, including the transformer ratio, the clamped electric impedance, and the open-circuit mechanical impedance. Each pMUT scheme was characterized under different acoustic loadings using the theoretically developed model, which was verified with finite element modeling (FEM) simulation. The electrode size was optimized to maximize the electromechanical transformer ratio. As such, the developed model could provide more insight into the design, optimization, and characterization of pMUTs and allow for performance comparison with their cMUT counterparts.

Investigation of a low NOx full-scale annular combustor

NASA Technical Reports Server (NTRS)

1982-01-01

An atmospheric test program was conducted to evaluate a low NOx annular combustor concept suitable for a supersonic, high-altitude aircraft application. The lean premixed combustor, known as the vortex air blast (VAB) concept, was tested as a 22.0-cm diameter model in the early development phases to arrive at basic design and performance criteria. Final demonstration testing was carried out on a full scale combustor of 0.66-m diameter. Variable geometry dilution ports were incorporated to allow operation of the combustor across the range of conditions between idle (T(in) = 422 K, T(out) = 917 K) and cruise (T(in) = 833 K, T(out) - 1778 K). Test results show that the design could meet the program NOx goal of 1.0 g NO2/kg fuel at a one-atmospheric simulated cruise condition.

Analysis of spatial and temporal spectra of liquid film surface in annular gas-liquid flow

NASA Astrophysics Data System (ADS)

Alekseenko, Sergey; Cherdantsev, Andrey; Heinz, Oksana; Kharlamov, Sergey; Markovich, Dmitriy

2013-09-01

Wavy structure of liquid film in annular gas-liquid flow without liquid entrainment consists of fast long-living primary waves and slow short-living secondary waves. In present paper, results of spectral analysis of this wavy structure are presented. Application of high-speed LIF technique allowed us to perform such analysis in both spatial and temporal domains. Power spectra in both domains are characterized by one-humped shape with long exponential tail. Influence of gas velocity, liquid Reynolds number, liquid viscosity and pipe diameter on frequency of the waves is investigated. When gravity effect is much lesser than the shear stress, similarity of power spectra at different gas velocities is observed. Using combination of spectral analysis and identification of characteristic lines of primary waves, frequency of generation of secondary waves by primary waves is measured.

Study of the collector/heat pipe cooled externally configured thermionic diode

NASA Technical Reports Server (NTRS)

1973-01-01

A collector/heat pipe cooled, externally configured (heated) thermionic diode module was designed for use in a laboratory test to demonstrate the applicability of this concept as the fuel element/converter module of an in-core thermionic electric power source. During the course of the program, this module evolved from a simple experimental mock-up into an advanced unit which was more reactor prototypical. Detailed analysis of all diode components led to their engineering design, fabrication, and assembly, with the exception of the collector/heat pipe. While several designs of high power annular wicked heat pipes were fabricated and tested, each exhibited unexpected performance difficulties. It was concluded that the basic cause of these problems was the formation of crud which interfered with the liquid flow in the annular passage of the evaporator region.

Some new results concerning the dynamic behavior of annular turbulent seals

NASA Technical Reports Server (NTRS)

Massmann, H.; Nordmann, R.

1985-01-01

The dynamic characteristics of annular turbulent seals applied in high pressure turbopumps can be described by stiffness, damping, and inertia coefficients. An improved procedure is presented for determining these parameters by using measurements made with newly developed test equipment. The dynamic system seal, consisting of the fluid between the cylindrical surfaces of the rotating shaft and the housing, is excited by test forces (input), and the relative motion between the surfaces (output) is measured. Transformation of the input and output time signals into the frequency domain leads to frequency response functions. An analytical model, depending on the seal parameters, is fitted to the measured data in order to identify the dynamic coefficients. Some new results are reported that show the dependencies of these coefficients with respect to the axial and radial Reynolds numbers and the geometrical data of the seal.

Geophysical expression of a buried niobium and rare earth element deposit: the Elk Creek carbonatite, Nebraska, USA

USGS Publications Warehouse

Drenth, Benjamin J.

2014-01-01

The lower Paleozoic Elk Creek carbonatite is a 6–8-km-diameter intrusive complex buried under 200 m of sedimentary rocks in southeastern Nebraska. It hosts the largest known niobium deposit in the U.S. and a rare earth element (REE) deposit. The carbonatite is composed of several lithologies, the relations of which are poorly understood. Niobium mineralization is most enriched within a magnetite beforsite (MB) unit, and REE oxides are most concentrated in a barite beforsite unit. The carbonatite intrudes Proterozoic country rocks. Efforts to explore the carbonatite have used geophysical data and drilling. A high-resolution airborne gravity gradient and magnetic survey was flown over the carbonatite in 2012. The carbonatite is associated with a roughly annular vertical gravity gradient high and a subdued central low and a central magnetic high surrounded by magnetic field values lower than those over the country rocks. Geophysical, borehole, and physical property data are combined for an interpretation of these signatures. The carbonatite is denser than the country rocks, explaining the gravity gradient high. Most carbonatite lithologies have weaker magnetic susceptibilities than those of the country rocks, explaining why the carbonatite does not produce a magnetic high at its margin. The primary source of the central magnetic high is interpreted to be mafic rocks that are strongly magnetized and are present in large volumes. MB is very dense (mean density 3200  kg/m3) and strongly magnetized (median 0.073 magnetic susceptibility), producing a gravity gradient high and contributing to the aeromagnetic high. Barite beforsite has physical properties similar to most of the carbonatite volume, making it a poor geophysical target. Geophysical anomalies indicate the presence of dense and strongly magnetized rocks at depths below existing boreholes, either a large volume of MB or another unknown lithology.

Sound propagation in and radiation from acoustically lined flow ducts: A comparison of experiment and theory

NASA Technical Reports Server (NTRS)

Plumblee, H. E., Jr.; Dean, P. D.; Wynne, G. A.; Burrin, R. H.

1973-01-01

The results of an experimental and theoretical study of many of the fundamental details of sound propagation in hard wall and soft wall annular flow ducts are reported. The theory of sound propagation along such ducts and the theory for determining the complex radiation impedance of higher order modes of an annulus are outlined, and methods for generating acoustic duct modes are developed. The results of a detailed measurement program on propagation in rigid wall annular ducts with and without airflow through the duct are presented. Techniques are described for measuring cut-on frequencies, modal phase speed, and radial and annular mode shapes. The effects of flow velocity on cut-on frequencies and phase speed are measured. Comparisons are made with theoretical predictions for all of the effects studies. The two microphone method of impedance is used to measure the effects of flow on acoustic liners. A numerical study of sound propagation in annular ducts with one or both walls acoustically lined is presented.

Annular feed air breathing fuel cell stack

DOEpatents

Wilson, Mahlon S.; Neutzler, Jay K.

1997-01-01

A stack of polymer electrolyte fuel cells is formed from a plurality of unit cells where each unit cell includes fuel cell components defining a periphery and distributed along a common axis, where the fuel cell components include a polymer electrolyte membrane, an anode and a cathode contacting opposite sides of the membrane, and fuel and oxygen flow fields contacting the anode and the cathode, respectively, wherein the components define an annular region therethrough along the axis. A fuel distribution manifold within the annular region is connected to deliver fuel to the fuel flow field in each of the unit cells. The fuel distribution manifold is formed from a hydrophilic-like material to redistribute water produced by fuel and oxygen reacting at the cathode. In a particular embodiment, a single bolt through the annular region clamps the unit cells together. In another embodiment, separator plates between individual unit cells have an extended radial dimension to function as cooling fins for maintaining the operating temperature of the fuel cell stack.

Flow directing means for air-cooled transformers

DOEpatents

Jallouk, Philip A.

1977-01-01

This invention relates to improvements in systems for force-cooling transformers of the kind in which an outer helical winding and an insulation barrier nested therein form an axially extending annular passage for cooling-fluid flow. In one form of the invention a tubular shroud is positioned about the helical winding to define an axially extending annular chamber for cooling-fluid flow. The chamber has a width in the range of from about 4 to 25 times that of the axially extending passage. Two baffles extend inward from the shroud to define with the helical winding two annular flow channels having hydraulic diameters smaller than that of the chamber. The inlet to the chamber is designed with a hydraulic diameter approximating that of the coolant-entrance end of the above-mentioned annular passage. As so modified, transformers of the kind described can be operated at significantly higher load levels without exceeding safe operating temperatures. In some instances the invention permits continuous operation at 200% of the nameplate rating.

Draft Tube Baffle (DTB) crystallizers: A study of stationary and dynamically behaving Crystal Size Distributions (CSD)

NASA Astrophysics Data System (ADS)

Deleer, B. G. M.

1981-11-01

Based on population balance, CSD behavior as a function of geometrical and operating variables was studied, using a crystallizer. A potash alum-water system, involving a separation technique which uses surface active agents and an apolar, organic liquid to separate potash alum crystals from mother liquid under the influence of gravity was used to check experimental findings against literature data. Results show action of annular settling spaces is strongly influenced by fluid velocities perpendicular to those directed upwards. The well-mixed volume decreases with increasing crystallizer size until a minimum effective volume is reached. As supersaturation is constant throughout the crystallizer volume under stationary operating conditions, the annular settling space behaves like a growth chamber for crystals in its volume. Swirl in the lower part of the annular volume introduces significant back mixing. Crystals within this space either grow and return to the well-mixed part, or withdraw from the annular volume permanently.

Annular lesions of cutaneous sarcoidosis with granulomatous vasculitis.

PubMed

Mizuno, Kana; Nguyen, Chuyen Thi Hong; Ueda-Hayakawa, Ikuko; Okamoto, Hiroyuki

2017-05-01

Sarcoidosis is known to be involved in diseases with vasculitis as sarcoid vasculitis. However, vasculitis in cutaneous sarcoidal lesions is extremely rare. Here we describe a case of sarcoidosis with multiple annular skin lesions with granulomatous vasculitis. A 62-year-old female was diagnosed with sarcoidosis by chest-abdominal computed tomographic examination and laboratory tests. The skin lesions had appeared on her lower limbs 2 years before. Physical examination showed multiple infiltrated annular eruptions on the lower extremities. A skin biopsy of an area of erythema showed multiple non-caseating epithelioid cell granulomas in the dermis and subcutaneous fat and granulomatous vasculitis with fibrinoid degeneration in the subcutaneous fat. There are two types of vasculitis in sarcoidosis: leukocytoclastic and granulomatous vasculitis. Ulcers and livedo were more common in granulomatous vasculitis than in leukocytoclastic vasculitis. The present case had unique annular skin lesions of sarcoidosis with granulomatous vasculitis. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Experimental equipment for measuring physical properties of the annular hydrostatic thrust bearing

NASA Astrophysics Data System (ADS)

Kozdera, Michal; Drábková, Sylva; Bojko, Marian

2014-03-01

The hydraulic circuit, through which the mineral oil is brought, is an important part of hydrostatic bearings. The annular hydrostatic thrust bearing consists of two sliding plates divided by a layer of mineral oil. In the lower plate, there are oil grooves which distribute the liquid between the sliding areas. The hydraulic circuit is made of two basic parts: the energy source and the controlling part. The hydraulic pump, which brings the liquid into the sliding bearing, is the source of the pressure energy. The sliding bearing is weighted down by axial force, which can be changed during the process. That's why in front of the particular oil grooves control components adjusting pressure and flow size are located. This paper deals with a project of a hydraulic circuit for regulation of fluid layer in the annular hydrostatic thrust bearing and the testing equipment for measuring its physical properties. It will include the issue of measuring loading capacity and height of the fluid layer in the annular hydrostatic thrust bearing.

Semi Inextensional Post Buckling Analysis of Annular Plates,

DTIC Science & Technology

1981-09-01

too. These methods have their advantages in accuracy but suffer from the drawback of being difficult to use for overall design data or for the...The fact that the high postbuckling curve of the plate approaches a straight line was observed eperimentally [81, [10], where the use of the two

ANNULAR IMPACTOR SAMPLING DEVICE

DOEpatents

Tait, G.W.C.

1959-03-31

A high-rate air sampler capable of sampling alphaemitting particles as small as 0.5 microns is described. The device is a cylindrical shaped cup that fits in front of a suction tube and which has sticky grease coating along its base. Suction forces contaminated air against the periodically monitored particle absorbing grease.

Conceptual techniques for reducing parasitic current gain of lateral pnp transistors

NASA Technical Reports Server (NTRS)

Gallagher, R. C.; Scott, J. M.

1969-01-01

Two techniques have been conceptually proposed as possible means of reducing parasitic beta in lateral p-n-p transistors. One method uses a degenerate substrate and high concentration P /plus/ guard-ring diffusion, another places the base contact at the center of an annular ring structure.

Terrain Traversing Device Having a Wheel with Microhooks

NASA Technical Reports Server (NTRS)

Wiltsie, Nicholas (Inventor); Carpenter, Kalind C. (Inventor); Parness, Aaron (Inventor)

2015-01-01

A terrain traversing device is described. The device includes an annular rotor element with a plurality of co-planar microspine hooks arranged on the periphery of the annular rotor element. Each microspine hook has an independently flexible suspension configuration that permits the microspine hook to initially engage an irregularity in a terrain surface at a preset initial engagement angle and subsequently engage the irregularity with a continuously varying engagement angle when the annular rotor element is rotated for urging the terrain traversing device to traverse a terrain surface. Improvements related to the design, fabrication and use of the microspine hooks in the device are also described.

Trap seal for open circuit liquid cooled turbines

DOEpatents

Grondahl, Clayton M.; Germain, Malcolm R.

1980-01-01

An improved trap seal for open circuit liquid cooled turbines is disclosed. The trap seal of the present invention includes an annular recess formed in the supply conduit of cooling channels formed in the airfoil of the turbine buckets. A cylindrical insert is located in the annular recesses and has a plurality of axial grooves formed along the outer periphery thereof and a central recess formed in one end thereof. The axial grooves and central recess formed in the cylindrical insert cooperate with the annular recess to define a plurality of S-shaped trap seals which permit the passage of liquid coolant but prohibit passage of gaseous coolant.

Resolution of 90 nm (lambda/5) in an optical transmission microscope with an annular condenser.

PubMed

Vainrub, Arnold; Pustovyy, Oleg; Vodyanoy, Vitaly

2006-10-01

Resolution of 90 nm was achieved with a research microscope simply by replacing the standard bright-field condenser with a homebuilt illumination system with a cardioid annular condenser. Diffraction gratings with 100 nm width lines as well as less than 100 nm size features of different-shaped objects were clearly visible on a calibrated microscope test slide. The resolution increase results from a known narrower diffraction pattern in coherent illumination for the annular aperture compared with the circular aperture. This explanation is supported by an excellent accord of calculated and measured diffraction patterns for a 50 nm radius disk.

Turbomachinery Laboratory Texas A and M University research progress on annular gas seals

NASA Technical Reports Server (NTRS)

Childs, Dara W.

1994-01-01

Three helically-grooved seals were tested and the results were compared to the MTI code SPIRALG. A smooth annular seal was tested at six eccentricity ratios from 0 to 0.5. The following are concluded in this viewgraph presentation: (1) Helical-grooved seals provide a substantial reduction in cross-coupled stiffness coefficients. Negative k(sub xy) values are obtained for no-swirl or low-swirl cases. (2) SPIRALG is completely unsuitable for the type of seal tested, namely, turbulent flow, wide grooves and lands, etc. (3) A good analysis code is needed to guide the design of helically-grooved annular seals including groove and smooth sections.

31 CFR 540.306 - Highly Enriched Uranium (HEU).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Highly Enriched Uranium (HEU). 540...) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly...

High indium content homogenous InAlN layers grown by plasma-assisted molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Kyle, Erin C. H.; Kaun, Stephen W.; Wu, Feng; Bonef, Bastien; Speck, James S.

2016-11-01

InAlN grown by plasma-assisted molecular beam epitaxy often contains a honeycomb microstructure. The honeycomb microstructure consists of 5-10 nm diameter aluminum-rich regions which are surrounded by indium-rich regions. Layers without this microstructure were previously developed for nominally lattice-matched InAlN and have been developed here for higher indium content InAlN. In this study, InAlN was grown in a nitrogen-rich environment with high indium to aluminum flux ratios at low growth temperatures. Samples were characterized by high-resolution x-ray diffraction, atomic force microscopy, high-angle annular dark-field scanning transmission electron microscopy, and atom probe tomography. Atomic force microscopy showed InAlN layers grown at temperatures below 450 °C under nitrogen-rich conditions were free of droplets. InAlN films with indium contents up to 81% were grown at temperatures between 410 and 440 °C. High-angle annular dark-field scanning transmission electron microscopy and atom probe tomography showed no evidence of honeycomb microstructure for samples with indium contents of 34% and 62%. These layers are homogeneous and follow a random alloy distribution. A growth diagram for InAlN of all indium contents is reported.

Biofilm Community Dynamics in Bench-Scale Annular Reactors Simulating Arrestment of Chloraminated Drinking Water Nitrification

EPA Science Inventory

Annular reactors (ARs) were used to study biofilm community succession and provide an ecological insight during nitrification arrestment through simultaneously increasing monochloramine (NH2Cl) and chlorine to nitrogen mass ratios, resulting in four operational periods (I to IV)....

Gimbaled-shoulder friction stir welding tool

NASA Technical Reports Server (NTRS)

Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

2010-01-01

A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

Low coke fuel injector for a gas turbine engine

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

Taylor, J.R.

This patent describes a gas turbine carbureting device for disposal in a down-stream flowing compressor discharge air flow. It comprises: a spin chamber defined by a generally annular housing including a closed forward end having a continuous unobstructed inner surface and an open aft end wherein the forward end is upstream of the aft end with respect tot he compressor discharge airflow; at least one exhaust tube having an inlet disposed within the spin chamber wherein the exhaust tube is radially spaced apart from the annular housing and which together with the annular housing forms at least in part amore » first annular air passage leading to the forward end; the housing having a fuel entrance and a swirling air entrance to the first annular air passage and spaced axially apart from each other, and wherein the swirling air entrance and fuel entrance are downstream of the closer forward end with respect to the compressor discharge flow; and wherein the first air passage is formed for flowing swirling air from the swirling air passage to the aft end in an upstream direction with respect to the compressor discharge flow and the exhaust tube inlet is disposed within the swirl chamber so as to reverse the axial direction of the swirling air off the forward end from an upstream direction to a downstream direction through the exhaust tube.« less

Assessment of heavy metal contamination in sediment at Sukinda ultramafic complex using HAADF-STEM analysis.

PubMed

Equeenuddin, Sk Md; Pattnaik, Binaya Kumar

2017-10-01

The Sukinda ultramafic complex in Odisha has the largest chromite reserve in India. Sediment derived from ultramafic rocks has been enriched with various metals. Further, mining activities enhance the influx of metals into sediment by dumping mine overburden and tailings in the open area. Metal concentration in sediment is found in order of Cr Total (Cr) > Mn > Ni > Co > Zn > Cu with average concentration 26,778 mg/kg, 3098 mg/kg, 1813 mg/kg, 184 mg/kg, 116 mg/kg and 44 mg/kg respectively. Concentration of Cr(VI) varies from 5.25 to 26.47 mg/L with an average of 12.27 mg/L. Based on various pollution indices, it is confirmed that the area is severely contaminated. Nano-scale goethite, kaolinite, clinochlore and chromite have been identified and have high concentration of Cr, Co and Ni. Goethite has shown maximum metal retention potential as deciphered by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The HAADF-STEM mapping and principal component analysis indicate that Cr and Co mostly derived from chromite whereas Ni and Zn are derived from serpentine. Later, these metals co-precipitate and/or adsorbed onto the goethite and clay minerals. Fractionation study of metals confirms that Cu is the most mobile element followed by Zn. However, at low pH condition Ni is mobilized and likely to be bioavailable. Though Cr mostly occurs in residual fraction but as its concentration is very high, a small proportion of exchangeable fraction contributes significantly in terms of its bioavailability. Thus bioavailable Cr can pose severe threat to the environment in the Sukinda ultramafic complex. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transcatheter pledget-assisted suture tricuspid annuloplasty (PASTA) to create a double-orifice valve.

PubMed

Khan, Jaffar M; Rogers, Toby; Schenke, William H; Greenbaum, Adam B; Babaliaros, Vasilis C; Paone, Gaetano; Ramasawmy, Rajiv; Chen, Marcus Y; Herzka, Daniel A; Lederman, Robert J

2018-02-06

Pledget-assisted suture tricuspid valve annuloplasty (PASTA) is a novel technique using marketed equipment to deliver percutaneous trans-annular sutures to create a double-orifice tricuspid valve. Tricuspid regurgitation is a malignant disease with high surgical mortality and no commercially available transcatheter solution in the US. Two iterations of PASTA were tested using trans-apical or trans-jugular access in swine. Catheters directed paired coronary guidewires to septal and lateral targets on the tricuspid annulus under fluoroscopic and echocardiographic guidance. Guidewires were electrified to traverse the annular targets and exchanged for pledgeted sutures. The sutures were drawn together and knotted, apposing septal and lateral targets, creating a double orifice tricuspid valve. Twenty-two pigs underwent PASTA. Annular and chamber dimensions were reduced (annular area, 10.1 ± 0.8 cm 2 to 3.8 ± 1.5 cm 2 (naïve) and 13.1 ± 1.5 cm 2 to 6.2 ± 1.0 cm 2 (diseased); septal-lateral diameter, 3.9 ± 0.3 mm to 1.4 ± 0.6 mm (naïve) and 4.4 ± 0.4 mm to 1.7 ± 1.0 mm (diseased); and right ventricular end-diastolic volume, 94 ± 13 ml to 85 ± 14 ml (naïve) and 157 ± 25 ml to 143 ± 20 ml (diseased)). MRI derived tricuspid regurgitation fraction fell from 32 ± 12% to 4 ± 5%. Results were sustained at 30 days. Pledget pull-through force was five-fold higher (40.6 ± 11.7N vs 8.0 ± 2.6N, P < .01) using this strategy compared to single puncture techniques used to anchor current investigational devices. Serious complications were related to apical access. PASTA reduces annular dimensions and tricuspid regurgitation in pigs. It may be cautiously applied to selected patients with severe tricuspid regurgitation and no options. This is the first transcatheter procedure, to our knowledge, to deliver standard pledgeted sutures to repair cardiac pathology. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

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

Peterson, Kenneth A.; Knudson, Richard T.; Smith, Frank R.

Generally annular full tape thickness conductors are formed in single or multiple tape layers, and then stacked to produce an annular solid conductive wall for enclosing an electromagnetic isolation cavity. The conductors may be formed using punch and fill operations, or by flowing conductor-containing material onto the tape edge surfaces that define the interior sidewalls of the cavity.

DETERMINATION OF THE STRONG ACIDITY OF ATMOSPHERIC FINE PARTICLES (<2.5 UM) USING ANNULAR DENUDER TECHNOLOGY

EPA Science Inventory

This report is a standardized methodology description for the determination of strong acidity of fine particles (less than 2.5 microns) in ambient air using annular denuder technology. his methodology description includes two parts: art A - Standard Method and Part B - Enhanced M...

RESIDENCE TIME DISTRIBUTION OF FLUIDS IN STIRRED ANNULAR PHOTOREACTORS

EPA Science Inventory

When gases flow through an annular photoreactor at constant rate, some of the gas spends more or less than the average residence time in the reactor. This spread of residence time can have an important effect on the performance of the reactor. this study tested how the residence...

Design of the Annular Suspension and Pointing System (ASPS) (including design addendum)

NASA Technical Reports Server (NTRS)

Cunningham, D.; Gismondi, T.; Hamilton, B.; Kendig, J.; Kiedrowski, J.; Vroman, A.; Wilson, G.

1980-01-01

The Annular Suspension and Pointing System is an experiment pointing mount designed for extremely precise 3 axis orientation of shuttle experiments. It utilizes actively controlled magnetic bearing to provide noncontacting vernier pointing and translational isolation of the experiment. The design of the system is presented and analyzed.

Electric Propulsion Apparatus

NASA Technical Reports Server (NTRS)

Patterson, Michael J. (Inventor)

2013-01-01

An electric propulsion machine includes an ion thruster having an annular discharge chamber housing an anode having a large surface area. The ion thruster includes flat annular ion optics with a small span to gap ratio. Optionally, a second electric propulsion thruster may be disposed in a cylindrical space disposed within an interior of the annulus.

Annular and Cylindrical Phased Array Geometries for Transrectal High-Intensity Focused Ultrasound (HIFU) using PZT and Piezocomposite Materials

NASA Astrophysics Data System (ADS)

Seip, Ralf; Chen, Wohsing; Carlson, Roy; Frizzell, Leon; Warren, Gary; Smith, Nadine; Saleh, Khaldon; Gerber, Gene; Shung, Kirk; Guo, Hongkai; Sanghvi, Narendra T.

2005-03-01

This paper presents engineering progress and the latest in-vitro and in-vivo results obtained with a 4.0 MHz, 20 element, PZT annular transrectal HIFU array and several 4.0 MHz, 211 element, PZT and piezocomposite cylindrical transrectal HIFU arrays for the treatment of prostate cancer. The geometries of both arrays were designed and analyzed to steer the HIFU beams to the desired sites in the prostate volume using multi-channel electronic drivers, with the intent to increase treatment efficiency and reliability for the next generation of HIFU systems. The annular array is able to focus in depth from 25 mm to 50 mm, generate total acoustic powers in excess of 60W, and has been integrated into a modified Sonablate®500 HIFU system capable of controlling such an applicator through custom treatment planning and execution software. Both PZT- and piezocomposite cylindrical arrays were constructed and their characteristics were compared for the transrectal applications. These arrays have been installed into appropriate transducer housings, and have undergone characterization tests to determine their total acoustic power output, focusing range (in depth and laterally), focus quality, efficiency, and comparison tests to determine the material and technology of choice (PZT or piezocomposite) for intra-cavity HIFU applications. Array descriptions, characterization results, in-vitro and in-vivo results, and an overview of their intended use through the application software is shown.

Mitral Annular Calcium and Mitral Stenosis Determined by Multidetector Computed Tomography in Patients Referred for Aortic Stenosis.

PubMed

Mejean, Simon; Bouvier, Erik; Bataille, Vincent; Seknadji, Patrick; Fourchy, Dominique; Tabet, Jean-Yves; Lairez, Olivier; Cormier, Bertrand

2016-10-15

Mitral annular calcium (MAC) is a common finding in older patients referred for transcatheter aortic valve implantation (TAVI). Multidetector computed tomography (MDCT) allows fine quantification of the calcific deposits. Our objective was to estimate the prevalence of MAC and associated mitral stenosis (MS) in patients referred for TAVI using MDCT. A cohort of 346 consecutive patients referred for TAVI evaluation was screened by MDCT for MAC: 174 had MAC (50%). Of these patients, 165 patients (95%) had mitral valve area (MVA) assessable by MDCT planimetry (age 83.8 ± 5.9 years). Median mitral calcium volume and MVA were 545 mm 3 (193 to 1,253 mm 3 ) and 234 mm 2 (187 to 297 mm 2 ), respectively. The MS was very severe, severe, and moderate in 2%, 22%, and 10% patients, respectively. By multivariate analysis, MVA was independently correlated to mitral calcium volume, aortic annular area, and some specific patterns of mitral leaflet calcium. Based on these findings, a formula was elaborated to predict the presence of a significant MS. In conclusion, MDCT allows detailed assessment of MAC in TAVI populations, demonstrating a high prevalence. Mitral analysis should become routine during MDCT screening before TAVI as it may alter therapeutic strategy. Copyright © 2016 Elsevier Inc. All rights reserved.

Sound Transmission through Two Concentric Cylindrical Sandwich Shells

NASA Technical Reports Server (NTRS)

Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

1996-01-01

This paper solves the problem of sound transmission through a system of two infinite concentric cylindrical sandwich shells. The shells are surrounded by external and internal fluid media and there is fluid (air) in the annular space between them. An oblique plane sound wave is incident upon the surface of the outer shell. A uniform flow is moving with a constant velocity in the external fluid medium. Classical thin shell theory is applied to the inner shell and first-order shear deformation theory is applied to the outer shell. A closed form for transmission loss is derived based on modal analysis. Investigations have been made for the impedance of both shells and the transmission loss through the shells from the exterior into the interior. Results are compared for double sandwich shells and single sandwich shells. This study shows that: (1) the impedance of the inner shell is much smaller than that of the outer shell so that the transmission loss is almost the same in both the annular space and the interior cavity of the shells; (2) the two concentric sandwich shells can produce an appreciable increase of transmission loss over single sandwich shells especially in the high frequency range; and (3) design guidelines may be derived with respect to the noise reduction requirement and the pressure in the annular space at a mid-frequency range.

Influence of the burner swirl on the azimuthal instabilities in an annular combustor

NASA Astrophysics Data System (ADS)

Mazur, Marek; Nygård, Håkon; Worth, Nicholas; Dawson, James

2017-11-01

Improving our fundamental understanding of thermoacoustic instabilities will aid the development of new low emission gas turbine combustors. In the present investigation the effects of swirl on the self-excited azimuthal combustion instabilities in a multi-burner annular annular combustor are investigated experimentally. Each of the burners features a bluff body and a swirler to stabilize the flame. The combustor is operated with an ethylene-air premixture at powers up to 100 kW. The swirl number of the burners is varied in these tests. For each case, dynamic pressure measurements at different azimuthal positions, as well as overhead imaging of OH* of the entire combustor are conducted simultaneously and at a high sampling frequency. The measurements are then used to determine the azimuthal acoustic and heat release rate modes in the chamber and to determine whether these modes are standing, spinning or mixed. Furthermore, the phase shift between the heat release rate and pressure and the shape of these two signals are analysed at different azimuthal positions. Based on the Rayleigh criterion, these investigations allow to obtain an insight about the effects of the swirl on the instability margins of the combustor. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement n° 677931 TAIAC).

High air volume to low liquid volume aerosol collector

DOEpatents

Masquelier, Donald A.; Milanovich, Fred P.; Willeke, Klaus

2003-01-01

A high air volume to low liquid volume aerosol collector. A high volume flow of aerosol particles is drawn into an annular, centripetal slot in a collector which directs the aerosol flow into a small volume of liquid pool contained is a lower center section of the collector. The annular jet of air impinges into the liquid, imbedding initially airborne particles in the liquid. The liquid in the pool continuously circulates in the lower section of the collector by moving to the center line, then upwardly, and through assistance by a rotating deflector plate passes back into the liquid at the outer area adjacent the impinging air jet which passes upwardly through the liquid pool and through a hollow center of the collector, and is discharged via a side outlet opening. Any liquid droplets escaping with the effluent air are captured by a rotating mist eliminator and moved back toward the liquid pool. The collector includes a sensor assembly for determining, controlling, and maintaining the level of the liquid pool, and includes a lower centrally located valve assembly connected to a liquid reservoir and to an analyzer for analyzing the particles which are impinged into the liquid pool.

The SSME seal test program: Leakage tests for helically-grooved seals

NASA Technical Reports Server (NTRS)

Childs, D. W.

1983-01-01

Helically grooved annular seal configurations were tested in highly turbulent flow to determine if reduced leakage and enhanced stability would result from the pumping action of the seal. It was found that: (1) leakage of a helically grooved seals decreases with running speed; (2) leakage reduction due to increased running speed is greater at lower values of R sub a; (3) an asymptote for leakage reduction is indicated with increasing running speed; (4) leakage is reduced by reducing the ridge (minimum) and average clearances; (5) leakage increases with increasing pitch angles and with increasing groove depth. Plain seals with smooth rotors and stators will leak more than a helically grooved seal. It was also found that plain seals with a rough rotor and a rough stator leak less than a properly designed helically grooved seal. A properly designed helically grooved seal consumes at least twice as much power as a conventional annular seal.

Characteristics of laser beam focusing with single spherical mirrors during laser treatment

NASA Astrophysics Data System (ADS)

Borkin, A. G.; Drobyazko, S. V.; Kosheleva, G. A.; Pavlovich, Yu. V.; Senatorov, Yu. M.; Fromm, V. A.; Kurchatov, I. V.

1988-04-01

Focusing of a laser beam with a single spherical mirror is analyzed, such a mirror being combined with a rotatable annular plane mirror in a coaxial configuration. Its focal length must be sufficiently large to ensure adequately high power density and to avoid shielding. When the distance from mirror to laser cavity is too large, then the laser beam may degenerate into a nonannular one and its focusing without loss may become unattainable. Tilting the spherical mirror will make this possible, even when the laser beam is not annular, if astigmatism as well as spherical aberration are minimized. Such a focusing mirror made of metal is theoretically shown to be much more effective than a focusing lens made of KC1 crystal; this has been confirmed experimentally in a CO sub 2 laser facility for perforation of tubular seperator meshes.

An analytical investigation of a conceptual design for the station transverse boom rotary joint structure

NASA Technical Reports Server (NTRS)

Lake, M. S.; Bush, H. G.

1986-01-01

A study was conducted to define an annular ring, discrete roller assembly concept for the space station transverse boom rotary joint. The concept was analyzed using closed-form and finite element techniques, to size structural members for a range of joint diameters and to determine necessary equivalent stiffnesses for the roller assemblies. Also, a mass study of the system was conducted to determine its practicality, and maximum loads in the joint were identified. To obtain the optimum balance between high stiffness and low structural mass in the design of the rotary joint, it is necessary to maximize the diameter of the annular ring within operational constraints (i.e., shuttle cargo bay size). Further, a rotary joint designed with the largest possible ring diameter will result in minimum operational loads in both the roller assemblies and the transition truss members while also allowing minimum design stiffnesses for the roller assemblies.

The Signature of Southern Hemisphere Atmospheric Circulation Patterns in Antarctic Precipitation

PubMed Central

Thompson, David W. J.; van den Broeke, Michiel R.

2017-01-01

Abstract We provide the first comprehensive analysis of the relationships between large‐scale patterns of Southern Hemisphere climate variability and the detailed structure of Antarctic precipitation. We examine linkages between the high spatial resolution precipitation from a regional atmospheric model and four patterns of large‐scale Southern Hemisphere climate variability: the southern baroclinic annular mode, the southern annular mode, and the two Pacific‐South American teleconnection patterns. Variations in all four patterns influence the spatial configuration of precipitation over Antarctica, consistent with their signatures in high‐latitude meridional moisture fluxes. They impact not only the mean but also the incidence of extreme precipitation events. Current coupled‐climate models are able to reproduce all four patterns of atmospheric variability but struggle to correctly replicate their regional impacts on Antarctic climate. Thus, linking these patterns directly to Antarctic precipitation variability may allow a better estimate of future changes in precipitation than using model output alone. PMID:29398735

Atomic bonding effects in annular dark field scanning transmission electron microscopy. I. Computational predictions

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

Odlyzko, Michael L.; Mkhoyan, K. Andre, E-mail: mkhoyan@umn.edu; Himmetoglu, Burak

2016-07-15

Annular dark field scanning transmission electron microscopy (ADF-STEM) image simulations were performed for zone-axis-oriented light-element single crystals, using a multislice method adapted to include charge redistribution due to chemical bonding. Examination of these image simulations alongside calculations of the propagation of the focused electron probe reveal that the evolution of the probe intensity with thickness exhibits significant sensitivity to interatomic charge transfer, accounting for observed thickness-dependent bonding sensitivity of contrast in all ADF-STEM imaging conditions. Because changes in image contrast relative to conventional neutral atom simulations scale directly with the net interatomic charge transfer, the strongest effects are seen inmore » crystals with highly polar bonding, while no effects are seen for nonpolar bonding. Although the bonding dependence of ADF-STEM image contrast varies with detector geometry, imaging parameters, and material temperature, these simulations predict the bonding effects to be experimentally measureable.« less

Measurement of Detonation Velocity for a Nonideal Heterogeneous Explosive in Axisymmetric and Two-Dimensional Geometries

NASA Astrophysics Data System (ADS)

Higgins, Andrew

2009-12-01

Detonation in a heterogeneous explosive with a relatively sparse concentration of reaction centers ("hot spots") is investigated experimentally. The explosive system considered is nitromethane gelled with PMMA and with glass microballoons (GMB's) in suspension. The detonation velocity is measured as a function of the characteristic charge dimension (diameter or thickness) in both axisymmetric and two-dimensional geometries. The use of a unique, annular charge geometry (with the diameter of the annulus much greater than the annular gap thickness) permits quasi-two-dimensional detonations to be observed without undesirable lateral rarefactions that result from a finite aspect ratio. The results confirm the prior findings of Gois et al. (1996) which show that, for a low concentration of GMB's, detonation propagation does not exhibit the expected 2:1 scaling from axisymmetric to planar geometries. This reinforces the idea that detonation in highly nonideal explosives is not governed exclusively by global front curvature.

Annular Ion Engine Concept and Development Status

NASA Technical Reports Server (NTRS)

Patterson, Michael J.

2016-01-01

The Annular Ion Engine (AIE) concept represents an evolutionary development in gridded ion thruster technology with the potential for delivering revolutionary capabilities. It has this potential because the AIE concept: (a) enables scaling of ion thruster technology to high power at specific impulse (Isp) values of interest for near-term mission applications, 5000 sec; and (b) it enables an increase in both thrust density and thrust-to-power (FP) ratio exceeding conventional ion thrusters and other electric propulsion (EP) technology options, thereby yielding the highest performance over a broad range in Isp. The AIE concept represents a natural progression of gridded ion thruster technology beyond the capabilities embodied by NASAs Evolutionary Xenon Thruster (NEXT) [1]. The AIE would be appropriate for: (a) applications which require power levels exceeding NEXTs capabilities (up to about 14 kW [2]), with scalability potentially to 100s of kW; and/or (b) applications which require FP conditions exceeding NEXTs capabilities.

Fuel and oxygen addition for metal smelting or refining process

DOEpatents

Schlichting, Mark R.

1994-01-01

A furnace 10 for smelting iron ore and/or refining molten iron 20 is equipped with an overhead pneumatic lance 40, through which a center stream of particulate coal 53 is ejected at high velocity into a slag layer 30. An annular stream of nitrogen or argon 51 enshrouds the coal stream. Oxygen 52 is simultaneously ejected in an annular stream encircling the inert gas stream 51. The interposition of the inert gas stream between the coal and oxygen streams prevents the volatile matter in the coal from combusting before it reaches the slag layer. Heat of combustion is thus more efficiently delivered to the slag, where it is needed to sustain the desired reactions occurring there. A second stream of lower velocity oxygen can be delivered through an outermost annulus 84 to react with carbon monoxide gas rising from slag layer 30, thereby adding still more heat to the furnace.

Fuel and oxygen addition for metal smelting or refining process

DOEpatents

Schlichting, M.R.

1994-11-22

A furnace for smelting iron ore and/or refining molten iron is equipped with an overhead pneumatic lance, through which a center stream of particulate coal is ejected at high velocity into a slag layer. An annular stream of nitrogen or argon enshrouds the coal stream. Oxygen is simultaneously ejected in an annular stream encircling the inert gas stream. The interposition of the inert gas stream between the coal and oxygen streams prevents the volatile matter in the coal from combusting before it reaches the slag layer. Heat of combustion is thus more efficiently delivered to the slag, where it is needed to sustain the desired reactions occurring there. A second stream of lower velocity oxygen can be delivered through an outermost annulus to react with carbon monoxide gas rising from slag layer, thereby adding still more heat to the furnace. 7 figs.

Lance for fuel and oxygen injection into smelting or refining furnace

DOEpatents

Schlichting, Mark R.

1994-01-01

A furnace 10 for smelting iron ore and/or refining molten iron 20 is equipped with an overhead pneumatic lance 40, through which a center stream of particulate coal 53 is ejected at high velocity into a slag layer 30. An annular stream of nitrogen or argon 51 enshrouds the coal stream. Oxygen 52 is simultaneously ejected in an annular stream encircling the inert gas stream 51. The interposition of the inert gas stream between the coal and oxygen streams prevents the volatile matter in the coal from combusting before it reaches the slag layer. Heat of combustion is thus more efficiently delivered to the slag, where it is needed to sustain the desired reactions occurring there. A second stream of lower velocity oxygen can be delivered through an outermost annulus 84 to react with carbon monoxide gas rising from slag layer 30, thereby adding still more heat to the furnace.

Lance for fuel and oxygen injection into smelting or refining furnace

DOEpatents

Schlichting, M.R.

1994-12-20

A furnace for smelting iron ore and/or refining molten iron is equipped with an overhead pneumatic lance, through which a center stream of particulate coal is ejected at high velocity into a slag layer. An annular stream of nitrogen or argon enshrouds the coal stream. Oxygen is simultaneously ejected in an annular stream encircling the inert gas stream. The interposition of the inert gas stream between the coal and oxygen streams prevents the volatile matter in the coal from combusting before it reaches the slag layer. Heat of combustion is thus more efficiently delivered to the slag, where it is needed to sustain the desired reactions occurring there. A second stream of lower velocity oxygen can be delivered through an outermost annulus to react with carbon monoxide gas rising from slag layer, thereby adding still more heat to the furnace. 7 figures.

Digital micromirror device based ophthalmoscope with concentric circle scanning.

PubMed

Damodaran, Mathi; Vienola, Kari V; Braaf, Boy; Vermeer, Koenraad A; de Boer, Johannes F

2017-05-01

Retinal imaging is demonstrated using a novel scanning light ophthalmoscope based on a digital micromirror device with 810 nm illumination. Concentric circles were used as scan patterns, which facilitated fixation by a human subject for imaging. An annular illumination was implemented in the system to reduce the background caused by corneal reflections and thereby to enhance the signal-to-noise ratio. A 1.9-fold increase in the signal-to-noise ratio was found by using an annular illumination aperture compared to a circular illumination aperture, resulting in a 5-fold increase in imaging speed and a better signal-to-noise ratio compared to our previous system. We tested the imaging performance of our system by performing non-mydriatic imaging on two subjects at a speed of 7 Hz with a maximum 20° (diameter) field of view. The images were shot noise limited and clearly show various anatomical features of the retina with high contrast.

Digital micromirror device based ophthalmoscope with concentric circle scanning

PubMed Central

Damodaran, Mathi; Vienola, Kari V.; Braaf, Boy; Vermeer, Koenraad A.; de Boer, Johannes F.

2017-01-01

Retinal imaging is demonstrated using a novel scanning light ophthalmoscope based on a digital micromirror device with 810 nm illumination. Concentric circles were used as scan patterns, which facilitated fixation by a human subject for imaging. An annular illumination was implemented in the system to reduce the background caused by corneal reflections and thereby to enhance the signal-to-noise ratio. A 1.9-fold increase in the signal-to-noise ratio was found by using an annular illumination aperture compared to a circular illumination aperture, resulting in a 5-fold increase in imaging speed and a better signal-to-noise ratio compared to our previous system. We tested the imaging performance of our system by performing non-mydriatic imaging on two subjects at a speed of 7 Hz with a maximum 20° (diameter) field of view. The images were shot noise limited and clearly show various anatomical features of the retina with high contrast. PMID:28663905

Application of an improved Nelson-Nguyen analysis to eccentric, arbitrary profile liquid annular seals

NASA Technical Reports Server (NTRS)

Padavala, Satyasrinivas; Palazzolo, Alan B.; Vallely, Pat; Ryan, Steve

1994-01-01

An improved dynamic analysis for liquid annular seals with arbitrary profile based on a method, first proposed by Nelson and Nguyen, is presented. An improved first order solution that incorporates a continuous interpolation of perturbed quantities in the circumferential direction, is presented. The original method uses an approximation scheme for circumferential gradients, based on Fast Fourier Transforms (FFT). A simpler scheme based on cubic splines is found to be computationally more efficient with better convergence at higher eccentricities. A new approach of computing dynamic coefficients based on external specified load is introduced. This improved analysis is extended to account for arbitrarily varying seal profile in both axial and circumferential directions. An example case of an elliptical seal with varying degrees of axial curvature is analyzed. A case study based on actual operating clearances of an interstage seal of the Space Shuttle Main Engine High Pressure Oxygen Turbopump is presented.

Analysis of a Segmented Annular Coplanar Capacitive Tilt Sensor with Increased Sensitivity.

PubMed

Guo, Jiahao; Hu, Pengcheng; Tan, Jiubin

2016-01-21

An investigation of a segmented annular coplanar capacitor is presented. We focus on its theoretical model, and a mathematical expression of the capacitance value is derived by solving a Laplace equation with Hankel transform. The finite element method is employed to verify the analytical result. Different control parameters are discussed, and each contribution to the capacitance value of the capacitor is obtained. On this basis, we analyze and optimize the structure parameters of a segmented coplanar capacitive tilt sensor, and three models with different positions of the electrode gap are fabricated and tested. The experimental result shows that the model (whose electrode-gap position is 10 mm from the electrode center) realizes a high sensitivity: 0.129 pF/° with a non-linearity of <0.4% FS (full scale of ± 40°). This finding offers plenty of opportunities for various measurement requirements in addition to achieving an optimized structure in practical design.

Nuclear reactor shutdown system

DOEpatents

Bhate, Suresh K.; Cooper, Martin H.; Riffe, Delmar R.; Kinney, Calvin L.

1981-01-01

An inherent shutdown system for a nuclear reactor having neutron absorbing rods affixed to an armature which is held in an upper position by a magnetic flux flowing through a Curie temperature material. The Curie temperature material is fixedly positioned about the exterior of an inner duct in an annular region through which reactor coolant flows. Elongated fuel rods extending from within the core upwardly toward the Curie temperature material are preferably disposed within the annular region. Upon abnormal conditions which result in high neutron flux and coolant temperature, the Curie material loses its magnetic permeability, breaking the magnetic flux path and allowing the armature and absorber rods to drop into the core, thus shutting down the fissioning reaction. The armature and absorber rods are retrieved by lowering the housing for the electromagnet forming coils which create a magnetic flux path which includes the inner duct wall. The coil housing then is raised, resetting the armature.

Stability of Wavy Films in Gas-Liquid Two-Phase Flows at Normal and Microgravity Conditions

NASA Technical Reports Server (NTRS)

Balakotaiah, V.; Jayawardena, S. S.

1996-01-01

For flow rates of technological interest, most gas-liquid flows in pipes are in the annular flow regime, in which, the liquid moves along the pipe wall in a thin, wavy film and the gas flows in the core region. The waves appearing on the liquid film have a profound influence on the transfer rates, and hence on the design of these systems. We have recently proposed and analyzed two boundary layer models that describe the characteristics of laminar wavy films at high Reynolds numbers (300-1200). Comparison of model predictions to 1-g experimental data showed good agreement. The goal of our present work is to understand through a combined program of experimental and modeling studies the characteristics of wavy films in annular two-phase gas-liquid flows under normal as well as microgravity conditions in the developed and entry regions.

Experimental clean combustor program, phase 1

NASA Technical Reports Server (NTRS)

Bahr, D. W.; Gleason, C. C.

1975-01-01

Full annular versions of advanced combustor designs, sized to fit within the CF6-50 engine, were defined, manufactured, and tested at high pressure conditions. Configurations were screened, and significant reductions in CO, HC, and NOx emissions levels were achieved with two of these advanced combustor design concepts. Emissions and performance data at a typical AST cruise condition were also obtained along with combustor noise data as a part of an addendum to the basic program. The two promising combustor design approaches evolved in these efforts were the Double Annular Combustor and the Radial/Axial Combustor. With versions of these two basic combustor designs, CO and HC emissions levels at or near the target levels were obtained. Although the low target NOx emissions level was not obtained with these two advanced combustor designs, significant reductions were relative to the NOx levels of current technology combustors. Smoke emission levels below the target value were obtained.

Liquid–Liquid Mixing Studies in Annular Centrifugal Contactors Comparing Stationary Mixing Vane Options

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

Wardle, Kent E.

2015-11-10

Comparative studies of multiphase operation of annular centrifugal contactors showing the impact of housing stationary mixing vane configuration. A number of experimental results for several different mixing vane options are reported with selected measurements in a lab-scale 5 cm contactor and 12.5 cm engineering-scale unit. Fewer straight vanes give greater mixingzone hold-up compared to curved vanes. Quantitative comparison of droplet size distribution also showed a significant decrease in mean diameter for four straight vanes versus eight curved vanes. This set of measurements gives a compelling case for careful consideration of mixing vane geometry when evaluating hydraulic operation and extraction processmore » efficiency of annular centrifugal contactors.« less

Cooling arrangement for a superconducting coil

DOEpatents

Herd, K.G.; Laskaris, E.T.

1998-06-30

A superconducting device is disclosed, such as a superconducting rotor for a generator or motor. A vacuum enclosure has an interior wall surrounding a cavity containing a vacuum. A superconductive coil is placed in the cavity. A generally-annularly-arranged, thermally-conductive sheet has an inward-facing surface contacting generally the entire outward-facing surface of the superconductive coil. A generally-annularly-arranged coolant tube contains a cryogenic fluid and contacts a generally-circumferential portion of the outward-facing surface of the sheet. A generally-annularly-arranged, thermally-insulative coil overwrap generally circumferentially surrounds the sheet. The coolant tube and the inward-facing surface of the coil overwrap together contact generally the entire outward-facing surface of the sheet. 3 figs.

Annular fuel and air co-flow premixer

DOEpatents

Stevenson, Christian Xavier; Melton, Patrick Benedict; York, William David

2013-10-15

Disclosed is a premixer for a combustor including an annular outer shell and an annular inner shell. The inner shell defines an inner flow channel inside of the inner shell and is located to define an outer flow channel between the outer shell and the inner shell. A fuel discharge annulus is located between the outer flow channel and the inner flow channel and is configured to inject a fuel flow into a mixing area in a direction substantially parallel to an outer airflow through the outer flow channel and an inner flow through the inner flow channel. Further disclosed are a combustor including a plurality of premixers and a method of premixing air and fuel in a combustor.

Liquid–liquid mixing studies in annular centrifugal contactors comparing stationary mixing vane options

DOE PAGES

Wardle, Kent E.

2015-09-11

Comparative studies of multiphase operation of an annular centrifugal contactor show the impact of housing stationary mixing vane configuration. A number of experimental results for several different mixing vane options are reported for operation of a 12.5 cm engineering-scale contactor unit. Fewer straight vanes give greater mixing-zone hold-up compared to curved vanes. Quantitative comparison of droplet size distribution also showed a significant decrease in mean diameter for four straight vanes versus eight curved vanes. This set of measurements gives a compelling case for careful consideration of mixing vane geometry when evaluating hydraulic operation and extraction process efficiency of annular centrifugalmore » contactors.« less

Gas flow path for a gas turbine engine

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

Montgomery, Matthew D.; Charron, Richard C.; Snyder, Gary D.

A duct arrangement in a can annular gas turbine engine. The gas turbine engine has a gas delivery structure for delivering gases from a plurality of combustors to an annular chamber that extends circumferentially and is oriented concentric to a gas turbine engine longitudinal axis for delivering the gas flow to a first row of blades A gas flow path is formed by the duct arrangement between a respective combustor and the annular chamber for conveying gases from each combustor to the first row of turbine blades The duct arrangement includes at least one straight section having a centerline thatmore » is misaligned with a centerline of the combustor.« less

An Experimental Study of Swirling Flows as Applied to Annular Combustors

NASA Technical Reports Server (NTRS)

Seal, Michael Damian, II

1997-01-01

This thesis presents an experimental study of swirling flows with direct applications to gas turbine combustors. Two separate flowfields were investigated: a round, swirling jet and a non-combusting annular combustor model. These studies were intended to allow both a further understanding of the behavior of general swirling flow characteristics, such as the recirculation zone, as well as to provide a base for the development of computational models. In order to determine the characteristics of swirling flows the concentration fields of a round, swirling jet were analyzed for varying amount of swirl. The experimental method used was a light scattering concentration measurement technique known as marker nephelometry. Results indicated the formation of a zone of recirculating fluid for swirl ratios (rotational speed x jet radius over mass average axial velocity) above a certain critical value. The size of this recirculation zone, as well as the spread angle of the jet, was found to increase with increase in the amount of applied swirl. The annular combustor model flowfield simulated the cold-flow characteristics of typical current annular combustors: swirl, recirculation, primary air cross jets and high levels of turbulence. The measurements in the combustor model made by the Laser Doppler Velocimetry technique, allowed the evaluation of the mean and rms velocities in the three coordinate directions, one Reynold's shear stress component and the turbulence kinetic energy: The primary cross jets were found to have a very strong effect on both the mean and turbulence flowfields. These cross jets, along with a large step change in area and wall jet inlet flow pattern, reduced the overall swirl in the test section to negligible levels. The formation of the strong recirculation zone is due mainly to the cross jets and the large step change in area. The cross jets were also found to drive a four-celled vortex-type motion (parallel to the combustor longitudinal axis) near the cross jet injection plane.

Flow interaction experiment. Volume 2: Aerothermal modeling, phase 2

NASA Technical Reports Server (NTRS)

Nikjooy, M.; Mongia, H. C.; Sullivan, J. P.; Murthy, S. N. B.

1993-01-01

An experimental and computational study is reported for the flow of a turbulent jet discharging into a rectangular enclosure. The experimental configurations consisting of primary jets only, annular jets only, and a combination of annular and primary jets are investigated to provide a better understanding of the flow field in an annular combustor. A laser Doppler velocimeter is used to measure mean velocity and Reynolds stress components. Major features of the flow field include recirculation, primary and annular jet interaction, and high turbulence. A significant result from this study is the effect the primary jets have on the flow field. The primary jets are seen to create statistically larger recirculation zones and higher turbulence levels. In addition, a technique called marker nephelometry is used to provide mean concentration values in the model combustor. Computations are performed using three levels of turbulence closures, namely k-epsilon model, algebraic second moment (ASM), and differential second moment (DSM) closure. Two different numerical schemes are applied. One is the lower-order power-law differencing scheme (PLDS) and the other is the higher-order flux-spline differencing scheme (FSDS). A comparison is made of the performance of these schemes. The numerical results are compared with experimental data. For the cases considered in this study, the FSDS is more accurate than the PLDS. For a prescribed accuracy, the flux-spline scheme requires a far fewer number of grid points. Thus, it has the potential for providing a numerical error-free solution, especially for three-dimensional flows, without requiring an excessively fine grid. Although qualitatively good comparison with data was obtained, the deficiencies regarding the modeled dissipation rate (epsilon) equation, pressure-strain correlation model, and the inlet epsilon profile and other critical closure issues need to be resolved before one can achieve the degree of accuracy required to analytically design combustion systems.

Flow interaction experiment. Volume 1: Aerothermal modeling, phase 2

NASA Technical Reports Server (NTRS)

Nikjooy, M.; Mongia, H. C.; Sullivan, J. P.; Murthy, S. N. B.

1993-01-01

An experimental and computational study is reported for the flow of a turbulent jet discharging into a rectangular enclosure. The experimental configurations consisting of primary jets only, annular jets only, and a combination of annular and primary jets are investigated to provide a better understanding of the flow field in an annular combustor. A laser Doppler velocimeter is used to measure mean velocity and Reynolds stress components. Major features of the flow field include recirculation, primary and annular jet interaction, and high turbulence. A significant result from this study is the effect the primary jets have on the flow field. The primary jets are seen to create statistically larger recirculation zones and higher turbulence levels. In addition, a technique called marker nephelometry is used to provide mean concentration values in the model combustor. Computations are performed using three levels of turbulence closures, namely k-epsilon model, algebraic second moment (ASM), and differential second moment (DSM) closure. Two different numerical schemes are applied. One is the lower-order power-law differencing scheme (PLDS) and the other is the higher-order flux-spline differencing scheme (FSDS). A comparison is made of the performance of these schemes. The numerical results are compared with experimental data. For the cases considered in this study, the FSDS is more accurate than the PLDS. For a prescribed accuracy, the flux-spline scheme requires a far fewer number of grid points. Thus, it has the potential for providing a numerical error-free solution, especially for three-dimensional flows, without requiring an excessively fine grid. Although qualitatively good comparison with data was obtained, the deficiencies regarding the modeled dissipation rate (epsilon) equation, pressure-strain correlation model, and the inlet epsilon profile and other critical closure issues need to be resolved before one can achieve the degree of accuracy required to analytically design combustion systems.

Annual Letter Report on ONR (Office of Naval Research) Contract Number N00014-85-K-0228.

DTIC Science & Technology

1985-12-02

olefination, ".. and thioketalization, are currently under way. Stabilization of these polyketones _ with respect to aldolization is particularly important for...11 NaH High Dilution 67 ..- expected that a knotted polyketone will be especially prone to intramolecular trans-annular reactions. The four-rung THYME

49 CFR 178.513 - Standards for boxes of natural wood.

Code of Federal Regulations, 2010 CFR

2010-10-01

... FOR PACKAGINGS Non-bulk Performance-Oriented Packaging Standards § 178.513 Standards for boxes of... to be highly stressed must be made using clenched or annular ring nails or equivalent fastenings. (3) Each part of the 4C2 box must be one piece or equivalent. Parts are considered equivalent to one piece...

The effect of inlet boundary layer thickness on the flow within an annular S-shaped duct

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

Sonoda, T.; Arima, T.; Oana, M.

1999-07-01

Experimental and numerical investigations were carried out to gain a better understanding of the flow characteristics within an annular S-shaped duct, including the effect of the inlet boundary layer (IBL) on the flow. A duct with six struts and the geometry as that used to connect compressor spools on the experimental small two-spool turbofan engine was investigated. A curved downstream annular passage with similar meridional flow path geometry to that of the centrifugal compressor has been fitted at the exit of S-shaped duct. Two types of the IBL (i.e., thin and thick IBL) were used. Results showed that large differencesmore » of flow patterns were observed at the S-shaped duct exit between two types of IBL, though the value of net total pressure loss has not been remarkably changed. According to overall total pressure loss, which includes the IBL loss, the total pressure loss was greatly increased near the hub as compared to that for a thin one. For the thick IBL, a vortex pair related to the hub-side horseshoe vortex and the separated flow found at the strut trailing edge has been clearly captured in the form of the total pressure loss contours and secondary flow vectors, experimentally and numerically. The high-pressure loss regions on either side of the strut wake near the hub may act on a downstream compressor performance. There is a much-distorted three-dimensional flow patterns at the exit of S-shaped duct. This means that the aerodynamic sensitivity of S-shaped duct to the IBL thickness is very high. Therefore, sufficient care is needed to design not only downstream aerodynamic components (for example, centrifugal impeller) but also upstream aerodynamic components (LPC OGV).« less

An analog integrated circuit beamformer for high-frequency medical ultrasound imaging.

PubMed

Gurun, Gokce; Zahorian, Jaime S; Sisman, Alper; Karaman, Mustafa; Hasler, Paul E; Degertekin, F Levent

2012-10-01

We designed and fabricated a dynamic receive beamformer integrated circuit (IC) in 0.35-μm CMOS technology. This beamformer IC is suitable for integration with an annular array transducer for high-frequency (30-50 MHz) intravascular ultrasound (IVUS) imaging. The beamformer IC consists of receive preamplifiers, an analog dynamic delay-and-sum beamformer, and buffers for 8 receive channels. To form an analog dynamic delay line we designed an analog delay cell based on the current-mode first-order all-pass filter topology, as the basic building block. To increase the bandwidth of the delay cell, we explored an enhancement technique on the current mirrors. This technique improved the overall bandwidth of the delay line by a factor of 6. Each delay cell consumes 2.1-mW of power and is capable of generating a tunable time delay between 1.75 ns to 2.5 ns. We successfully integrated the fabricated beamformer IC with an 8-element annular array. Experimental test results demonstrated the desired buffering, preamplification and delaying capabilities of the beamformer.

Frozen lattice and absorptive model for high angle annular dark field scanning transmission electron microscopy: A comparison study in terms of integrated intensity and atomic column position measurement.

PubMed

Alania, M; Lobato, I; Van Aert, S

2018-01-01

In this paper, both the frozen lattice (FL) and the absorptive potential (AP) approximation models are compared in terms of the integrated intensity and the precision with which atomic columns can be located from an image acquired using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM). The comparison is made for atoms of Cu, Ag, and Au. The integrated intensity is computed for both an isolated atomic column and an atomic column inside an FCC structure. The precision has been computed using the so-called Cramér-Rao Lower Bound (CRLB), which provides a theoretical lower bound on the variance with which parameters can be estimated. It is shown that the AP model results into accurate measurements for the integrated intensity only for small detector ranges under relatively low angles and for small thicknesses. In terms of the attainable precision, both methods show similar results indicating picometer range precision under realistic experimental conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

An Inversion Method for Reconstructing Hall Thruster Plume Parameters from the Line Integrated Measurements (Postprint)

DTIC Science & Technology

2007-07-01

Technical Paper 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER An Inversion Method for Reconstructing Hall Thruster Plume...298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 An Inversion Method for Reconstructing Hall Thruster Plume Parameters from Line Integrated Measurements... Hall thruster is a high specific impulse electric thruster that produces a highly ionized plasma inside an annular chamber through the use of high

LABORATORY AND NUMERICAL INVESTIGATIONS OF RESIDENCE TIME DISTRIBUTION OF FLUIDS IN LAMINAR FLOW STIRRED ANNULAR PHOTOREACTOR

EPA Science Inventory

Laboratory and Numerical Investigations of Residence Time Distribution of Fluids in Laminar Flow Stirred Annular Photoreactor

E. Sahle-Demessie1, Siefu Bekele2, U. R. Pillai1

1U.S. EPA, National Risk Management Research Laboratory
Sustainable Technology Division,...

49 CFR 179.400-3 - Type.

Code of Federal Regulations, 2010 CFR

2010-10-01

... essentially concentric within an outer jacket of circular cross section, with the out of roundness of both the inner tank and outer jacket limited in accordance with Paragraph UG-80 in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter); (2) Have the annular space evacuated after filling the annular...

49 CFR 179.400-3 - Type.

Code of Federal Regulations, 2011 CFR

2011-10-01

... essentially concentric within an outer jacket of circular cross section, with the out of roundness of both the inner tank and outer jacket limited in accordance with Paragraph UG-80 in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter); (2) Have the annular space evacuated after filling the annular...

49 CFR 179.400-3 - Type.

Code of Federal Regulations, 2012 CFR

2012-10-01

... essentially concentric within an outer jacket of circular cross section, with the out of roundness of both the inner tank and outer jacket limited in accordance with Paragraph UG-80 in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter); (2) Have the annular space evacuated after filling the annular...

49 CFR 179.400-3 - Type.

Code of Federal Regulations, 2014 CFR

2014-10-01

... essentially concentric within an outer jacket of circular cross section, with the out of roundness of both the inner tank and outer jacket limited in accordance with Paragraph UG-80 in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter); (2) Have the annular space evacuated after filling the annular...

Liquid-Vapor Flow Regime Transitions for Spacecraft Heat Transfer Loops

DTIC Science & Technology

1988-12-01

effects of fluid properties on flow regime transitions. 5 A carnauba wax with no additives was used because it resists dissolution by oil. 19 4.2...importance of an annular flow entrance geometry and of waxing the tube wall to change its wetting properties (to prevent inverse annular flow) were

[A rare form of granuloma annulare].

PubMed

Bogdanowski, T; Wygledowska-Kania, M

1995-01-01

We present a four-year-old girl with a doubly rare form of granuloma annulare with non-typical localisation of superficial nodules on the palms and predisposition to ulceration which is very rare in this type of superficial nodules. The diagnosis was proved by histological examination. After the local cryotherapy (ethyl chloride) the lesions almost completely disappeared.

Acute Renal Infarction Secondary to Calcific Embolus from Mitral Annular Calcification

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

Bande, Dinesh; Abbara, Suhny; Kalva, Sanjeeva P., E-mail: skalva@partners.org

2011-06-15

We report a case of a 62-year-old man who presented with right groin pain who subsequently was found to have a renal infarct secondary to calcific embolus from mitral annular calcification on CT and angiography. We briefly review the literature and discuss the importance of this entity in clinical practice.

Design curves for circular and annular duct silencers

NASA Technical Reports Server (NTRS)

Watson, Willie R.; Ramakrishnan, R.

1989-01-01

Conventional models of sound propagation between porous walls (Scott, 1946) are adapted in order to calculate design curves for the lined circular and annular-duct silencers used in HVAC systems. The derivation of the governing equations is outlined, and results for two typical cases are presented graphically. Good agreement with published experimental data is demonstrated.

49 CFR 179.400-3 - Type.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-3 Type. (a) A tank... (IBR, see § 171.7 of this subchapter); (2) Have the annular space evacuated after filling the annular space with an approved insulating material; (3) Have the inner tank heads designed concave to pressure...

Eccentricity effects upon the flow field inside a whirling annular seal

NASA Technical Reports Server (NTRS)

Morrison, Gerald L.; Deotte, Robert E., Jr.; Das, Purandar G.; Thames, H. Davis

1994-01-01

The flow field inside a whirling annular seal operating at a Reynolds number of 24,000 and a Taylor number of 6600 has been measured using a 3-D laser Doppler anemometer system. Two eccentricity ratios were considered, 0.10 and 0.50. The seal has a diameter of 164 mm, is 37.3 mm long, and has a clearance of 1.27 mm. The rotor was mounted eccentrically on the shaft such that the whirl ratio is 1.0 and the rotor follows a circular orbit. The mean axial velocity is not uniform around the circumference of the seal; near the inlet a region characterized by high velocity of the seal. By the exit, another region of high axial velocity is not uniform around the circumference of the seal; near the inlet a region characterized by high velocity of the seal. By the exit, another region of high axial velocity has developed, this time on the suction side of the seal. The magnitude and azimuthal distance of the migration increased with increasing whirl amplitude (eccentricity). Throughout the seal length, the azimuthal mean velocity varied inversely with the mean axial velocity. Increasing the whirl amplitude did not increase the magnitude of the azimuthal velocity at the seal exit.

Computer fluid dynamics (CFD) study of a micro annular gear pump

NASA Astrophysics Data System (ADS)

Stan, Liviu-Constantin; Cǎlimǎnescu, Ioan

2016-12-01

Micro technology makes it possible to design products simply, efficiently and sustainably and at the same time, opens up the creation of new functionalities. The field of application of the micro annular gear pumps lies in analytical instrumentation, mechanical and plant engineering, chemical and pharmaceutical process engineering as well as in new markets like fuel cells or biotechnology, organic electronics or aerospace. The purpose of this paper is to investigate by using the powerful ANSYS 16 CFX module the hydrodynamic behavior of an 8/9 teeth annular gear pump. The solving of solids evolving inside fluids was very cumbersome until the advent of the Ansys immersed solid technology. By deploying this technology for very special topics like the CFD analysis of Micro annular gear pumps, credible and reliable results may be pulled leading thus the way for more in depth studies like geometrical a functional optimization of the existing devices. This paper is a valuable guide for the professionals working in the design field of micro pumps handing them a new and powerful design tool.

Standing wave acoustic levitation on an annular plate

NASA Astrophysics Data System (ADS)

Kandemir, Mehmet Hakan; Çalışkan, Mehmet

2016-11-01

In standing wave acoustic levitation technique, a standing wave is formed between a source and a reflector. Particles can be attracted towards pressure nodes in standing waves owing to a spring action through which particles can be suspended in air. This operation can be performed on continuous structures as well as in several numbers of axes. In this study an annular acoustic levitation arrangement is introduced. Design features of the arrangement are discussed in detail. Bending modes of the annular plate, known as the most efficient sound generation mechanism in such structures, are focused on. Several types of bending modes of the plate are simulated and evaluated by computer simulations. Waveguides are designed to amplify waves coming from sources of excitation, that are, transducers. With the right positioning of the reflector plate, standing waves are formed in the space between the annular vibrating plate and the reflector plate. Radiation forces are also predicted. It is demonstrated that small particles can be suspended in air at pressure nodes of the standing wave corresponding to a particular bending mode.

Investigation of free vibration analysis of functionally graded annular piezoelectric plate using COMSOL

NASA Astrophysics Data System (ADS)

Sharma, Trivendra Kumar; Parashar, Sandeep Kumar

2018-05-01

In the present age functionally graded piezoelectric materials (FGPM) are increasingly being used as actuators and sensors. In spite of the fact that the piezoelectric coupling coefficient for shear d15 has much higher value in comparison to d31 or d33, it is far less utilized for the applications due to complex nature of the shear induced vibrations. In this work three dimensional free vibration analysis of functionally graded piezoelectric material annular plates with free-free boundary conditions is presented. The annular FGPM plate is polarized along the radial direction while the electric field is applied along the thickness direction inducing flexural vibrations of the plate due to d15 effect of functionally graded piezoelectric materials. The material properties are assumed to have a power law variation along the thickness. COMSOL Multiphysics is used to obtain the natural frequencies and modeshapes. Detailed numerical study is performed to ascertain the effect of variation in power law index and various geometrical parameters. The results presented shall be helpful in optimizing the existing applications and developing the new ones utilizing the FGPM annular plates.

Annular and central heavy pigment deposition on the posterior lens capsule in the pigment dispersion syndrome: pigment deposition on the posterior lens capsule in the pigment dispersion syndrome.

PubMed

Turgut, Burak; Türkçüoğlu, Peykan; Deniz, Nurettin; Catak, Onur

2008-12-01

To report annular and central heavy pigment deposition on the posterior lens capsule in a case of pigment dispersion syndrome. Case report. A 36-year-old female with bilateral pigment dispersion syndrome presented with progressive decrease in visual acuity in the right eye over the past 1-2 years. Clinical examination revealed the typical findings of pigment dispersion syndrome including bilateral Krunkenberg spindles, iris transillumination defects, and dense trabecular meshwork pigmentation. Remarkably, annular and central dense pigmentation of the posterior lens capsule was noted in the right eye. Annular pigment deposition on the posterior lens capsule may be a rare finding associated with pigment dispersion syndrome. Such a finding suggests that there may be aqueous flow into the retrolental space in some patients with this condition. The way of central pigmentation is the entrance of aqueous to Berger's space. In our case, it is probable that spontaneous detachment of the anterior hyaloid membrane aided this entrance.

78 FR 37925 - Continuation of the National Emergency With Respect to the Disposition of Russian Highly Enriched...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-24

... National Emergency With Respect to the Disposition of Russian Highly Enriched Uranium On June 25, 2012, by... America and the Government of the Russian Federation Concerning the Disposition of Highly Enriched Uranium... Russian highly enriched uranium declared in Executive Order 13617. [[Page 37926

Simplified flangeless unisex waveguide coupler assembly

DOEpatents

Michelangelo, Dimartino; Moeller, Charles P.

1993-01-01

A unisex coupler assembly is disclosed capable of providing a leak tight coupling for waveguides with axial alignment of the waveguides and rotational capability. The sealing means of the coupler assembly are not exposed to RF energy, and the coupler assembly does not require the provision of external flanges on the waveguides. In a preferred embodiment, O ring seals are not used and the coupler assembly is, therefore, bakeable at a temperature up to about 150.degree. C. The coupler assembly comprises a split collar which clamps around the waveguides and a second collar which fastens to the split collar. The split collar contains an inner annular groove. Each of the waveguides is provided with an external annular groove which receives a retaining ring. The split collar is clamped around one of the waveguides with the inner annular groove of the split collar engaging the retaining ring carried in the external annular groove in the waveguide. The second collar is then slipped over the second waveguide behind the annular groove and retaining ring therein and the second collar is coaxially secured by fastening means to the split collar to draw the respective waveguides together by coaxial force exerted by the second collar against the retaining ring on the second waveguide. A sealing ring is placed against an external sealing surface at a reduced external diameter end formed on one waveguide to sealingly engage a corresponding sealing surface on the other waveguide as the waveguides are urged toward each other.

Simplified flangeless unisex waveguide coupler assembly

DOEpatents

Michelangelo, D.; Moeller, C.P.

1993-05-04

A unisex coupler assembly is disclosed capable of providing a leak tight coupling for waveguides with axial alignment of the waveguides and rotational capability. The sealing means of the coupler assembly are not exposed to RF energy, and the coupler assembly does not require the provision of external flanges on the waveguides. In a preferred embodiment, O ring seals are not used and the coupler assembly is, therefore, bakeable at a temperature up to about 150 C. The coupler assembly comprises a split collar which clamps around the waveguides and a second collar which fastens to the split collar. The split collar contains an inner annular groove. Each of the waveguides is provided with an external annular groove which receives a retaining ring. The split collar is clamped around one of the waveguides with the inner annular groove of the split collar engaging the retaining ring carried in the external annular groove in the waveguide. The second collar is then slipped over the second waveguide behind the annular groove and retaining ring therein and the second collar is coaxially secured by fastening means to the split collar to draw the respective waveguides together by coaxial force exerted by the second collar against the retaining ring on the second waveguide. A sealing ring is placed against an external sealing surface at a reduced external diameter end formed on one waveguide to sealingly engage a corresponding sealing surface on the other waveguide as the waveguides are urged toward each other.

Simplified flangeless unisex waveguide coupler assembly

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

Michelangelo, D.; Moeller, C.P.

1993-05-04

A unisex coupler assembly is disclosed capable of providing a leak tight coupling for waveguides with axial alignment of the waveguides and rotational capability. The sealing means of the coupler assembly are not exposed to RF energy, and the coupler assembly does not require the provision of external flanges on the waveguides. In a preferred embodiment, O ring seals are not used and the coupler assembly is, therefore, bakeable at a temperature up to about 150 C. The coupler assembly comprises a split collar which clamps around the waveguides and a second collar which fastens to the split collar. Themore » split collar contains an inner annular groove. Each of the waveguides is provided with an external annular groove which receives a retaining ring. The split collar is clamped around one of the waveguides with the inner annular groove of the split collar engaging the retaining ring carried in the external annular groove in the waveguide. The second collar is then slipped over the second waveguide behind the annular groove and retaining ring therein and the second collar is coaxially secured by fastening means to the split collar to draw the respective waveguides together by coaxial force exerted by the second collar against the retaining ring on the second waveguide. A sealing ring is placed against an external sealing surface at a reduced external diameter end formed on one waveguide to sealingly engage a corresponding sealing surface on the other waveguide as the waveguides are urged toward each other.« less

De Vega Annuloplasty for Functional Tricupsid Regurgitation: Concept of Tricuspid Valve Orifice Index to Optimize Tricuspid Valve Annular Reduction

PubMed Central

Hwang, Ho Young; Chang, Hyoung Woo; Jeong, Dong Seop

2013-01-01

We evaluated long-term results of De Vega annuloplasty measured by cylindrical sizers for functional tricuspid regurgitation (FTR) and analyzed the impact of measured annular size on the late recurrence of tricuspid valve regurgitation. Between 2001 and 2011, 177 patients (57.9±10.5 yr) underwent De Vega annuloplasty for FTR. Three cylindrical sizers (actual diameters of 29.5, 31.5, and 33.5 mm) were used to reproducibly reduce the tricuspid annulus. Long-term outcomes were evaluated and risk factor analyses for the recurrence of FTR ≥3+ were performed. Measured annular diameter indexed by patient's body surface area was included in the analyses as a possible risk factor. Operative mortality occurred in 8 patients (4.5%). Ten-year overall and cardiac death-free survivals were 80.5% and 90.8%, respectively. Five and 10-yr freedom rates from recurrent FTR were 96.5% and 93.1%, respectively. Cox proportional hazard model revealed that higher indexed annular size was the only risk factor for the recurrence of FTR (P=0.006). A minimal P value approach demonstrated that indexed annular diameter of 22.5 mm/m2 was a cut-off value predicting the recurrence of FTR. De Vega annuloplasty for FTR results in low rates of recurrent FTR in the long-term. Tricuspid annulus should be reduced appropriately considering patients' body size to prevent recurrent FTR. PMID:24339705

Prognostication of valvular aortic stenosis using tissue Doppler echocardiography: underappreciated importance of late diastolic mitral annular velocity.

PubMed

Poh, Kian-Keong; Chan, Mark Yan-Yee; Yang, Hong; Yong, Quek-Wei; Chan, Yiong-Huak; Ling, Lieng H

2008-05-01

Intact left atrial booster pump function helps maintain cardiac compensation in patients with aortic valve stenosis (AS). Because late diastolic mitral annular (A') velocity reflects left atrial systolic function, we hypothesized that A' velocity correlates with plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) level and clinical outcome in AS. We prospectively enrolled 53 consecutive patients (median age 74 years) with variable degrees of AS, in sinus rhythm, and left ventricular ejection fraction greater than 50%. Indices of valvular stenosis, left ventricular diastolic dysfunction, and mitral annular motion were correlated with plasma NT-proBNP and a composite clinical end point comprising cardiac death and symptom-driven aortic valve replacement. Tissue Doppler echocardiographic parameters, including early diastolic (E') velocity and A' velocity and ratio of early diastolic transmitral (E) to E' velocity (E/E') at the annular septum correlated better with NT-proBNP levels than body surface area-indexed aortic valve area. Eighteen patients had the composite end point, which was univariately predicted by body surface area-indexed aortic valve area, NT-proBNP, and all tissue Doppler echocardiographic indices. This outcome was most strongly predicted by the combination of septal A' velocity and E/E' ratio in bivariate Cox modeling. Septal annular A' velocity less than 9.6 cm/s was associated with significantly reduced event-free survival (Kaplan Meier log rank = 27.3, P < .0001) and predicted the end point with a sensitivity, specificity, and accuracy of 94%, 80%, and 85%, respectively. In patients with AS and normal ejection fraction, annular tissue Doppler echocardiographic indices may better reflect the physiologic consequences of afterload burden on the left ventricle than body surface area-indexed aortic valve area. Lower A' velocity is a predictor of cardiac death and need for valve surgery, suggesting an important role for compensatory left atrial booster pump function.

Study of the heat-transfer crisis on heat-release surfaces of annular channels with swirl and transit flows

NASA Astrophysics Data System (ADS)

Boltenko, E. A.

2016-10-01

The results of the experimental study of the heat-transfer crisis on heat-release surfaces of annular channels with swirl and transit flow are presented. The experiments were carried out using electric heated annular channels with one and (or) two heat-release surfaces. For the organization of transit flow on a convex heat-release surface, four longitudinal ribs were installed uniformly at its perimeter. Swirl flow was realized using a capillary wound tightly (without gaps) on the ribs. The ratio between swirl and transit flows in the annular gap was varied by applying longitudinal ribs of different height. The experiments were carried out using a closed-type circulatory system. The experimental data were obtained in a wide range of regime parameters. Both water heated to the temperature less than the saturation temperature and water-steam mixture were fed at the inlet of the channels. For the measurement of the temperature of the heat-release surfaces, chromel-copel thermocouples were used. It was shown that the presence of swirl flow on a convex heatrelease surface led to a significant decrease in critical heat flows (CHF) compared to a smooth surface. To increase CHF, it was proposed to use the interaction of swirl flows of the heat carrier. The second swirl flow was transit flow, i.e., swirl flow with the step equal to infinity. It was shown that CHF values for a channel with swirl and transit flow in all the studied range of regime parameters was higher than CHF values for both a smooth annular channel and a channel with swirl. The empirical ratios describing the dependence of CHF on convex and concave heat-release surfaces of annular channels with swirl and transit flow on the geometrical characteristics of channels and the regime parameters were obtained. The experiments were carried out at the pressure p = 3.0-16.0 MPa and the mass velocity ρw = 250-3000 kg/(m2s).

Investigation into aerodynamic and heat transfer of annular channel with inner and outer surface of the shape truncated cone and swirling fluid flow

NASA Astrophysics Data System (ADS)

Leukhin, Yu L.; Pankratov, E. V.; Karpov, S. V.

2017-11-01

We have carried out Investigation into aerodynamic and convective heat transfer of the annular channel. Inner or outer surface of annular channel has shape of blunt-nosed cone tapering to outlet end. Truncated cone connects to a cyclone swirling flow generator. Asymmetric and unsteady flow from the swirling generator in the shape of periodic process gives rise to the formation of secondary flows of the type Taylor-Görtler vortices. These vortices occupy the whole space of the annular channel, with the axes, which coincide with the motion direction of the major stream. Contraction of cross-sectional area of channel (in both cases 52%) causes a marked increase in total velocity of flow, primarily due to its axial component and promotes a more intensive vortex generation. Vortex structures have a significant influence on both average heat transfer and surface distribution. At cross-sections of the annular channel we observe similarity of curves describing distribution of total velocity about wall and heat flux density on the surface. The coordinates of maximum and minimum values of velocity and heat flux coincide. At the average cross-section channel of maximum value of heat transfer is greater than minimum of about by a factor of 2.7 times for outer heat transfer surface and about by a factor of 1.7 times for inner heat transfer surface. Taper channel has a much higher influence on heat transfer of the inner surface than the outer surface and manifests itself at lower values of dimensionless axial coordinate. For the investigated taper cone geometry of the annular channel the heat transfer coefficient of inner surface increases at the outlet section and exceeds value in comparison with straight-line section by 91 … 98%. Heat transfer of the outer cylinder in the same section increases only by 5 … 11%. The increase in average heat transfer over the surfaces is 36% and 4% respectively.

Cost savings associated with prevention of recurrent lumbar disc herniation with a novel annular closure device: a multicenter prospective cohort study.

PubMed

Parker, Scott L; Grahovac, Gordan; Vukas, Duje; Ledic, Darko; Vilendecic, Milorad; McGirt, Matthew J

2013-09-01

Same-level recurrent disc herniation is a well-defined complication following lumbar discectomy. Reherniation results in increased morbidity and health care costs. Techniques to reduce these consequences may improve outcomes and reduce cost after lumbar discectomy. In a prospective cohort study, we set out to evaluate the cost associated with surgical management of recurrent, same-level lumbar disc herniation following primary discectomy. Forty-six consecutive European patients undergoing lumbar discectomy for a single-level herniated disc at two institutions were prospectively followed with clinical and radiographic evaluations. A second consecutive cohort of 30 patients undergoing 31 lumbar discectomies with implantation of an annular closure device was followed at the same hospitals and same follow-up intervals. Cost estimates for reherniation were modeled on Medicare national allowable payment amounts (direct cost) and patient work-day losses (indirect cost). Annular closure and control cohorts were matched at baseline. By 2 years follow-up, symptomatic recurrent same-level disc herniation occurred in three (6.5%) patients in the control cohort versus zero (0%) patients in the annular closure cohort. For patients experiencing recurrent disc herniation, mean estimated direct and indirect cost of management of recurrent disc herniation was $34,242 and $3,778, respectively. Use of an annular closure device potentially results in a cost savings of $222,573 per 100 primary discectomy procedures performed (or $2,226 per discectomy), based solely on the reduction of reoperated reherniations when modeled on U.S. Medicare costs. Recurrent disc herniation did not occur in any patients after annular closure within the 12-month follow-up. The reduction in the incidence of reherniation was associated with potentially significant cost savings. Development of novel techniques to prevent recurrent lumbar disc herniation is warranted to decrease the associated morbidity and health care costs associated with this complication. Georg Thieme Verlag KG Stuttgart · New York.

Flow of two immiscible fluids in a periodically constricted tube: Transitions to stratified, segmented, churn, spray, or segregated flow

NASA Astrophysics Data System (ADS)

Fraggedakis, D.; Kouris, Ch.; Dimakopoulos, Y.; Tsamopoulos, J.

2015-08-01

We study the flow of two immiscible, Newtonian fluids in a periodically constricted tube driven by a constant pressure gradient. Our volume-of-fluid algorithm is used to solve the governing equations. First, the code is validated by comparing its predictions to previously reported results for stratified and pulsing flow. Then, it is used to capture accurately all the significant topological changes that take place. Initially, the fluids have a core-annular arrangement, which is found to either remain the same or change to a different arrangement depending on the fluid properties, the pressure driving the flow, or the flow geometry. The flow-patterns that appear are the core-annular, segmented, churn, spray, and segregated flow. The predicted scalings near pinching of the core fluid concur with similarity predictions and earlier numerical results [I. Cohen et al., "Two fluid drop snap-off problem: Experiments and theory," Phys. Rev. Lett. 83, 1147-1150 (1999)]. Flow-pattern maps are constructed in terms of the Reynolds and Weber numbers. Our result provides deeper insights into the mechanism of the pattern transitions and is in agreement with previous studies on core-annular flow [Ch. Kouris and J. Tsamopoulos, "Core-annular flow in a periodically constricted circular tube, I. Steady state, linear stability and energy analysis," J. Fluid Mech. 432, 31-68 (2001) and Ch. Kouris et al., "Comparison of spectral and finite element methods applied to the study of interfacial instabilities of the core-annular flow in an undulating tube," Int. J. Numer. Methods Fluids 39(1), 41-73 (2002)], segmented flow [E. Lac and J. D. Sherwood, "Motion of a drop along the centreline of a capillary in a pressure-driven flow," J. Fluid Mech. 640, 27-54 (2009)], and churn flow [R. Y. Bai et al., "Lubricated pipelining—Stability of core annular-flow. 5. Experiments and comparison with theory," J. Fluid Mech. 240, 97-132 (1992)].

Performance of a Cylindrical Hall-Effect Thruster Using Permanent Magnets

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Raitses, Y.; Merino, E.; Fisch, N. J.

2009-01-01

While annular Hall thrusters can operate at high efficiency at kW power levels, it is difficult to construct one that operates over a broad envelope from 1 kW down to 100 W while maintaining an efficiency of 45-55%. Scaling to low power while holding the main dimensionless parameters constant requires a decrease in the thruster channel size and an increase in the magnetic field strength. Increasing the magnetic field becomes technically challenging since the field can saturate the miniaturized inner components of the magnetic circuit and scaling down the magnetic circuit leaves very little room for magnetic pole pieces and heat shields. In addition, the central magnetic pole piece defining the interior wall of the annular channel can experience excessive heat loads in a miniaturized Hall thruster, with the temperature eventually exceeding the Curie temperature of the material and in extreme circumstances leading to accelerated erosion of the channel wall. An alternative approach is to employ a cylindrical Hall thruster (CHT) geometry. Laboratory model CHTs have operated at power levels ranging from 50 W up to 1 kW. These thrusters exhibit performance characteristics that are comparable to conventional, annular Hall thrusters of similar size. Compared to the annular Hall thruster, the CHTs insulator surface area to discharge chamber volume ratio is lower. Consequently, there is the potential for reduced wall losses in the channel of a CHT, and any reduction in wall losses should translate into lower channel heating rates and reduced erosion, making the CHT geometry promising for low-power applications. This potential for high performance in the low-power regime has served as the impetus for research and development efforts aimed at understanding and improving CHT performance. Recently, a 2.6 cm channel diameter permanent magnet CHT (shown in Fig. 1) was tested. This thruster has the promise of reduced power consumption over previous CHT iterations that employed electromagnets. Data are presented to expose the effect different controllable parameters have on the discharge and to summarize performance measurements (thrust, Isp, efficiency) obtained using a thrust stand. In addition, beam current data are presented to show the effect of the magnetic field topology on the plume profile and current utilization and to gain insight into the thruster s operation. These data extend and improve upon the results previously presented by the authors in Ref. [1].

Dry pulverized solid material pump

DOEpatents

Meyer, John W.; Bonin, John H.; Daniel, Jr., Arnold D.

1984-07-31

Apparatus is shown for substantially increasing the feed rate of pulverized material into a pressurized container. The apparatus includes a rotor that is mounted internal to the pressurized container. The pulverized material is fed into an annular chamber defined by the center of the rotor. A plurality of impellers are mounted within the annular chamber for imparting torque to the pulverized material.

Focusing of concentric piecewise vector Bessel-Gaussian beam

NASA Astrophysics Data System (ADS)

Li, Jinsong; Fang, Ying; Zhou, Shenghua; Ye, Youxiang

2010-12-01

The focusing properties of a concentric piecewise vector Bessel-Gaussian beam are investigated in this paper. The beam consists of three portions: the center circular portion and outer annular portion are radially polarized, while the inner annular portion is generalized polarized with tunable polarized angle. Numerical simulations show that the evolution of focal pattern is altered considerably with different Bessel parameters in the Bessel term of the vector Bessel-Gaussian beam. The polarized angle also affects the focal pattern remarkably. Some interesting focal patterns may appear, such as two-peak, dark hollow focus; ring focus; spherical shell focus; cylindrical shell focus; and multi-ring-peak focus, and transverse focal switch occurs with increasing polarized angle of the inner annular portion, which may be used in optical manipulation.

Mechanical seal with textured sidewall

DOEpatents

Khonsari, Michael M.; Xiao, Nian

2017-02-14

The present invention discloses a mating ring, a primary ring, and associated mechanical seal having superior heat transfer and wear characteristics. According to an exemplary embodiment of the present invention, one or more dimples are formed onto the cylindrical outer surface of a mating ring sidewall and/or a primary ring sidewall. A stationary mating ring for a mechanical seal assembly is disclosed. Such a mating ring comprises an annular body having a central axis and a sealing face, wherein a plurality of dimples are formed into the outer circumferential surface of the annular body such that the exposed circumferential surface area of the annular body is increased. The texture added to the sidewall of the mating ring yields superior heat transfer and wear characteristics.

Research and implementation of the algorithm for unwrapped and distortion correction basing on CORDIC for panoramic image

NASA Astrophysics Data System (ADS)

Zhang, Zhenhai; Li, Kejie; Wu, Xiaobing; Zhang, Shujiang

2008-03-01

The unwrapped and correcting algorithm based on Coordinate Rotation Digital Computer (CORDIC) and bilinear interpolation algorithm was presented in this paper, with the purpose of processing dynamic panoramic annular image. An original annular panoramic image captured by panoramic annular lens (PAL) can be unwrapped and corrected to conventional rectangular image without distortion, which is much more coincident with people's vision. The algorithm for panoramic image processing is modeled by VHDL and implemented in FPGA. The experimental results show that the proposed panoramic image algorithm for unwrapped and distortion correction has the lower computation complexity and the architecture for dynamic panoramic image processing has lower hardware cost and power consumption. And the proposed algorithm is valid.

Amyloid-β annular protofibrils evade fibrillar fate in Alzheimer disease brain.

PubMed

Lasagna-Reeves, Cristian A; Glabe, Charles G; Kayed, Rakez

2011-06-24

Annular protofibrils (APFs) represent a new and distinct class of amyloid structures formed by disease-associated proteins. In vitro, these pore-like structures have been implicated in membrane permeabilization and ion homeostasis via pore formation. Still, evidence for their formation and relevance in vivo is lacking. Herein, we report that APFs are in a distinct pathway from fibril formation in vitro and in vivo. In human Alzheimer disease brain samples, amyloid-β APFs were associated with diffuse plaques, but not compact plaques; moreover, we show the formation of intracellular APFs. Our results together with previous studies suggest that the prevention of amyloid-β annular protofibril formation could be a relevant target for the prevention of amyloid-β toxicity in Alzheimer disease.

Phase-locking of combination-cylinder discharge CO2 laser

NASA Astrophysics Data System (ADS)

Xu, Yonggen

2014-05-01

A new type of laser resonator is presented to obtained good coherent beam and the parameters of the laser beam are calculated. The principle of phase-locking is described based on the injection-locking, the properties of the injected beam in the resonator are studied in detail. The output beam from output mirror is an annular laser beam with zero central intensity. An analytical expression for the annular laser beam through the ABCD optical system is derived. Typical numerical examples are calculated to confirm our analytical results. It is shown that the good coherent beam can be obtained through phase-locking, and the central intensity of annular beam through ABCD optical system will become maximum when the parameters of laser beam are selected reasonably.

Annular Lichenoid Dermatitis of Youth: A Report of 2 Cases and a Review of the Literature.

PubMed

Vázquez-Osorio, I; González-Sabín, M; Gonzalvo-Rodríguez, P; Rodríguez-Díaz, E

2016-01-01

Annular lichenoid dermatitis of youth is a lichenoid dermatosis of unknown etiology. It mostly affects children and adolescents and has well-defined clinical and histological characteristics that permit a diagnosis. We present 2 new cases of annular lichenoid dermatitis of youth with classical clinical features in 2 girls, aged 2 and 4 years. The histologic findings, however, differed from those reported in the literature in that the lichenoid inflammatory infiltrate was located primarily at the top of the dermal papillae and not at the tips of the rete ridges. In both cases, the lesions regressed spontaneously without treatment. Copyright © 2016 AEDV. Published by Elsevier España, S.L.U. All rights reserved.

Traveling Wave Amplifier Driven by a Large Diameter Annular Electron Beam in a Disk-Loaded Structure

DTIC Science & Technology

2015-10-30

IV MARY LOU ROBINSON, DR-IV Project Officer Chief, High Power Electromagnetics Division This report is published in the interest of scientific and...unlimited. 13. SUPPLEMENTARY NOTES OPS-15-9244 14. ABSTRACT This project studies the viability of a high - power traveling wave tube (TWT) using a novel...CHRISTINE codes. Fair agreement was observed. The preliminary conclusion is that the disk-on-rod TWT is a viable, high - power extension to the conventional

Signal and power roll ring testing update

NASA Technical Reports Server (NTRS)

Smith, Dennis W.

1989-01-01

The development of the roll ring as a long-life, low-torque alternative to the slip ring is discussed. A roll ring consists of one or more circular flexures captured by their own spring force in the annular space between two concentric conductors or contact rings. The advantages of roll rings over other types of electrical transfer devices are: extremely low drag torque, high transfer efficiencies in high-power configurations, extremely low wear debris generation, long life, and low weight for high-power applications.

Super-Resolution Image Reconstruction by Nonlocal Means Applied to High-Angle Annular Darkfield Scanning Transmission Electron Microscopy (HAADF-STEM)

DTIC Science & Technology

2009-10-06

When talking about superresolution we always mean to recover the level of resolution set by the microscope, but by using a time series of low...on low resolution possibly very noisy data, is not feasible. Thus, standard superresolution concepts as described above that are based on registration

30 CFR 250.1611 - Blowout preventer systems tests, actuations, inspections, and maintenance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... conducting high-pressure tests, all BOP systems shall be tested to a pressure of 200 to 300 psi. (b) Ram-type BOP's and the choke manifold shall be pressure tested with water to rated working pressure or as otherwise approved by the District Manager. Annular type BOP's shall be pressure tested with water to 70...

Circular RNAs and exosomes in cancer: a mysterious connection.

PubMed

Hou, J; Jiang, W; Zhu, L; Zhong, S; Zhang, H; Li, J; Zhou, S; Yang, S; He, Y; Wang, D; Chen, X; Deng, F; Zhang, Q; Wang, J; Hu, J; Zhang, W; Ding, L; Zhao, J; Tang, J

2018-03-13

Circular RNAs (CircRNAs) are a type of non-coding RNAs (NcRNAs) with a closed annular structure. Until next-generation sequencing (NGS) is developed, the misunderstanding of circRNAs 'splicing error' has changed, and the mysterious veil of circRNAs has been revealed. NGS provides an approach to investigate circRNAs. Many scholars point out that circRNAs may play an important role in many diseases, especially cancer. At the same time, exosomes, as a kind of extracellular vesicles loaded with many contents, are a hotspot in recent years. They can act as 'messengers' between cells, especially in cancer. Lately, it is interesting circRNAs are enriched and stable in exosomes, also called exo-circRNAs, and there have been several articles on circRNAs associated with exosomes. In this review, we summarize the characteristics of circRNAs, especially its main functions. Then, we briefly introduce exosomes and their function in cancer. Finally, the known relation between circRNAs and exosomes is discussed. With further researches, exo-circRNAs may be a novel pathway for cancer diagnosis and targeted therapy.

The circular Uneged Uul structure (East Gobi Basin, Mongolia) - Geomorphic and structural evidence for meteorite impact into an unconsolidated coarse-clastic target?

NASA Astrophysics Data System (ADS)

Schmieder, Martin; Seyfried, Hartmut; Gerel, Ochir

2013-03-01

The Uneged Uul structure is a ˜10 km circular, complex, multi-ridged domal feature in the Unegt subbasin of the East Gobi Basin, southeastern Mongolia. As revealed by remote sensing and recent field reconnaissance, the central part of the Uneged Uul structure comprises a complex central peak of outward-radiating curved ridges, composed of stratigraphically uplifted greenschist-facies basement schists, surrounded by an annular moat. The most prominent feature of the structure is a central annular ridge ˜3 km in diameter composed of pebble-boulder conglomerates and gravels of the Upper Jurassic Sharilyn Formation, surrounded by three outer domal ridges composed of Lower Cretaceous conglomeratic sandstones and gypsum clays. Jurassic conglomerates forming the main part of the central annular ridge show effects of severe internal deformation. The original population of pebbles, cobbles and boulders appears moderately displaced and mostly broken but nowhere aligned along shear planes or foliated. Primary sedimentary features, such as cross-lamination or imbrication, have been obliterated. We explain this penetrative brecciation as a result of dissipative shearing caused by a strong and rapid singular event that in magnitude was beyond the range of the common crustal tectonics recorded elsewhere in this region. Disrupted and chaotically distributed conglomeratic sandstone beds in the central annular ridge dip in highly variable directions on a local scale but show an apparent SE-NW trend of bedding plane alignment. Further outside, the tilted and uplifted Upper Jurassic to Lower Cretaceous strata of the domal area are overlain by the flat-lying Upper Cretaceous, which stratigraphically constrains the timing of deformation at the Uneged Uul structure to most likely the Early Cretaceous. Endogenic formation models, such as magmatism and salt, gypsum, or mud diapirism, fail to explain the nature of the Uneged Uul structure. The Uneged Uul structure bears a set of geomorphic and structural features resembling those at some eroded complex impact structures on Earth. Morphologically similar central peaks are observed at the Spider and Matt Wilson impact structures in Australia; the central annular ridge reminds of that at Gosses Bluff in Australia; the outer domal ridges might correspond to ring-like features as known from Tin Bider in Algeria. We, therefore, cautiously propose that an impact may have produced the Uneged Uul feature causing structural uplift (˜1000 m) of basement rocks at its center. So far, no convincing evidence for shock metamorphism could be proven by field work and petrographic analyses. However, it is likely that at the time of the deformation event the unconsolidated conglomerates were highly porous and possibly immersed in groundwater buffering the propagation of sudden stress-reducing deformation. Further studies will be in order to unravel the nature of the Uneged Uul structure, which should be considered a promising possible impact structure.

Thermal breeder fuel enrichment zoning

DOEpatents

Capossela, Harry J.; Dwyer, Joseph R.; Luce, Robert G.; McCoy, Daniel F.; Merriman, Floyd C.

1992-01-01

A method and apparatus for improving the performance of a thermal breeder reactor having regions of higher than average moderator concentration are disclosed. The fuel modules of the reactor core contain at least two different types of fuel elements, a high enrichment fuel element and a low enrichment fuel element. The two types of fuel elements are arranged in the fuel module with the low enrichment fuel elements located between the high moderator regions and the high enrichment fuel elements. Preferably, shim rods made of a fertile material are provided in selective regions for controlling the reactivity of the reactor by movement of the shim rods into and out of the reactor core. The moderation of neutrons adjacent the high enrichment fuel elements is preferably minimized as by reducing the spacing of the high enrichment fuel elements and/or using a moderator having a reduced moderating effect.

Annular and Total Solar Eclipses of 2003

NASA Technical Reports Server (NTRS)

Espenak, Fred; Anderson, Jay

2002-01-01

On Saturday, 2003 May 31, an annular eclipse of the Sun will be visible from a broad corridor that traverses the North Atlantic. The path of the Moon's antumbral shadow begins in northern Scotland, crosses Iceland and central Greenland, and ends at sunrise in Baffin Bay (Canada). A partial eclipse will be seen within the much broader path of the Moon's penumbral shadow, which includes most of Europe, the Middle East, central and northern Asia, and northwestern North America. The trajectory of the Moon's shadow is quite unusual during this event. The shadow axis passes to the far north where it barely grazes Earth's surface. In fact, the northern edge of the antumbra actually misses Earth so that one path limit is defined by the day/night terminator rather than by the shadow's upper edge. As a result, the track of annularity has a peculiar "D" shape that is nearly 1200 kilometers wide. Since the eclipse occurs just three weeks prior to the northern summer solstice, Earth's northern axis is pointed sunwards by 22.8 deg. As seen from the Sun, the antumbral shadow actually passes between the North Pole and the terminator. As a consequence of this extraordinary geometry, the path of annularity runs from east to west rather than the more typical west to east. The event transpires near the Moon's ascending node in Taurus five degrees north of Aldebaran. Since apogee occurs three days earlier (May 28 at 13 UT), the Moon's apparent diameter (29.6 arc-minutes) is still too small to completely cover the Sun (31.6 arc-minutes) resulting in an annular eclipse.

Design and fabrication of sub-wavelength annular apertures on fiber tip for femtosecond laser machining

NASA Astrophysics Data System (ADS)

Tung, Yen-Chun; Chung, Ming-Han; Sung, I.-Hui; Lee, Chih-Kung

2014-03-01

Adopting optical technique to pursue micromachining must make a compromise between the focal spot sizes the depth of focus. The focal spot size determines the minimum features can be fabricated. On the other hand, the depth of focus influences the ease of alignment in positioning the fabrication light beam. A typical approach to bypass the diffraction limit is to adopt the near-field approach, which has spot size in the range of the optical fiber tip. However, the depth of focus of the emitted light beam will be limited to tens of nanometers in most cases, which posts a difficult challenge to control the distance between the optical fiber tip and the sample to be machined optically. More specifically, problems remained in this machining approach, which include issues such as residue induced by laser ablation tends to deposit near the optical fiber tip and leads to loss of coupling efficiency. We proposed a method based on illuminating femtosecond laser through a sub-wavelength annular aperture on metallic film so as to produce Bessel light beam of sub-wavelength while maintaining large depth of focus first. To further advance the ease of use in one such system, producing sub-wavelength annular aperture on a single mode optical fiber head with sub-wavelength focusing ability is detailed. It is shown that this method can be applied in material machining with an emphasis to produce high aspect ratio structure. Simulations and experimental results are presented in this paper.

Testing the kibble-zurek scenario with annular josephson tunnel junctions

PubMed

Kavoussanaki; Monaco; Rivers

2000-10-16

In parallel with Kibble's description of the onset of phase transitions in the early Universe, Zurek has provided a simple picture for the onset of phase transitions in condensed matter systems, supported by agreement with experiments in 3He and superconductors. We show how experiments with annular Josephson tunnel junctions can, and do, provide further support for this scenario.

Introduction to Pump Rotordynamics

DTIC Science & Technology

2006-11-01

reducing leakage as well as cross-coupled stiffness coefficients [5]. Figure 6 depicts two textured seals and a conventional labyrinth seal (teeth on...well documented in the technical literature are due to the aerodynamic effects of labyrinth seals and the hydrodynamic effects of lubricated...Figure 4: Typical Squeeze Film Damper Configuration. 2.4 Annular Pressure Seals Radial seals (annular, labyrinth or honeycomb) separate regions of

Subsonic annular wing theory with application to flow about nacelles

NASA Technical Reports Server (NTRS)

Mann, M. J.

1974-01-01

A method has recently been developed for calculating the flow over a subsonic nacelle at zero angle of attack. The method makes use of annular wing theory and boundary-layer theory and has shown good agreement with both experimental data and more complex theoretical solutions. The method permits variation of the mass flow by changing the size of a center body.

Annular convective-radiative fins with a step change in thickness, and temperature-dependent thermal conductivity and heat transfer coefficient

NASA Astrophysics Data System (ADS)

Barforoush, M. S. M.; Saedodin, S.

2018-01-01

This article investigates the thermal performance of convective-radiative annular fins with a step reduction in local cross section (SRC). The thermal conductivity of the fin's material is assumed to be a linear function of temperature, and heat transfer coefficient is assumed to be a power-law function of surface temperature. Moreover, nonzero convection and radiation sink temperatures are included in the mathematical model of the energy equation. The well-known differential transformation method (DTM) is used to derive the analytical solution. An exact analytical solution for a special case is derived to prove the validity of the obtained results from the DTM. The model provided here is a more realistic representation of SRC annular fins in actual engineering practices. Effects of many parameters such as conduction-convection parameters, conduction-radiation parameter and sink temperature, and also some parameters which deal with step fins such as thickness parameter and dimensionless parameter describing the position of junction in the fin on the temperature distribution of both thin and thick sections of the fin are investigated. It is believed that the obtained results will facilitate the design and performance evaluation of SRC annular fins.

Linearization of an annular image by using a diffractive optic

NASA Technical Reports Server (NTRS)

Matthys, Donald R.

1996-01-01

The goal for this project is to develop the algorithms for fracturing the zones defined by the mapping transformation, and to actually produce the binary optic in an appropriate setup. In 1984 a side-viewing panoramic viewing system was patented, consisting of a single piece of glass with spherical surfaces which produces a 360 degree view of the region surrounding the lens which extends about 25 degrees in front of and 20 degrees behind the lens. The system not only produces images of good quality, it is also afocal, i.e., images stay in focus for objects located right next to the lens as well as those located far from the lens. The lens produced a panoramic view in an annular shaped image, and so the lens was called a PAL (panoramic annular lens). When applying traditional measurements to PAL images, it is found advantageous to linearize the annular image. This can easily be done with a computer and such a linearized image can be produced within about 40 seconds on current microcomputers. However, this process requires a frame-grabber and a computer, and is not real-time. Therefore, it was decided to try to perform this linearization optically by using a diffractive optic.

A case of annular pancreas with Wirsung's duct encircling the duodenum: embryological hypothesis based on cholangiopancreatographic and immunohistochemical findings.

PubMed

Fukai, Manami; Kamisawa, Terumi; Horiguchi, Shin-Ichirou; Hishima, Tsunekazu; Kuruma, Sawako; Chiba, Kazuro; Koizumi, Satomi; Tabata, Taku; Nagao, Sayaka; Kikuyama, Masataka; Honda, Goro; Kurata, Masanao

2017-06-01

We present a resected case of annular pancreas in which Wirsung's duct encircled the duodenum and continued directly to the main pancreatic duct in the body and tail. Furthermore, Wirsung's duct coursed along the right side of the lower bile duct near the major duodenal papilla. Histologically, the islets of Langerhans in the annular pancreas were irregular in shape and were characterized by a striking abundance of pancreatic polypeptide (PP)-positive cells. The PP-rich area that encircled the duodenum was fused with the PP-poor area in the head of the pancreas. The following embryological hypothesis is proposed. The tip of the ventral pancreatic anlage adhered to the duodenal wall and stretched to form a ring during clockwise rotation. The rotation was incomplete, and the pancreatic duct did not cross over the lower bile duct. Since there was adequate ventral anlage in the lower part of the head of the pancreas, fusion between the ducts of the ventral and dorsal anlagen did not occur. The tip of the ventral anlage overgrew and adhered to the dorsal anlage, and the annular duct fused with the main duct of the dorsal anlage.

Injection Characteristics of Non-Swirling and Swirling Annular Liquid Sheets

NASA Technical Reports Server (NTRS)

Harper, Brent (Technical Monitor); Ibrahim, E. A.; McKinney, T. R.

2004-01-01

A simplified mathematical model, based on body-fitted coordinates, is formulated to study the evolution of non-swirling and swirling liquid sheet emanated from an annular nozzle in a quiescent surrounding medium. The model provides predictions of sheet trajectory, thickness and velocity at various liquid mass flow rates and liquid-swirler angles. It is found that a non-swirling annular sheet converges toward its centerline and assumes a bell shape as it moves downstream from the nozzle. The bell radius, and length are more pronounced at higher liquid mass flow rates. The thickness of the non-swirling annular sheet increases while its stream-wise velocity decreases with an increase in mass flow rate. The introduction of swirl results in the formation of a diverging hollow-cone sheet. The hollow-cone divergence from its centerline is enhanced by an increase in liquid mass flow rate or liquid-swirler angle. The hollow- cone sheet its radius, curvature and stream-wise velocity increase while its thickness and tangential velocity decrease as a result of increasing the mass flow rate or liquid-swirler angle. The present results are compared with previous studies and conclusions are drawn.

Annular ring zoom system using two positive axicons

NASA Astrophysics Data System (ADS)

Dickey, Fred M.; Conner, Jacob D.

2011-10-01

The production of an annular ring of light with a variable diameter has applications in laser material processing and machining, particle manipulation, and corneal surgery. This can readily be accomplished using a positive and negative axicon pair. However, negative axicons are very expensive and difficult to obtain with small diameters. In this paper, we present a design of an annular ring zoom system using two positive axicons. One axicon is placed a distance before a primary lens that is greater than some prescribed minimum, and the second axicon is placed after the primary lens. The position of the second axicon determines the ring diameter. The ring diameter can be zoomed from some maximum design size to a zero diameter ring (spot). Experimental results from a developmental system will be presented.

Treatment of Annular Elastolytic Giant Cell Granuloma With Topical Tretinoin.

PubMed

Wagenseller, Aubrey; Larocca, Cecilia; Vashi, Neelam A

2017-07-01

Annular elastolytic giant cell granuloma, also known as actinic granuloma, is a rare skin condition with a chronic course that is often resistant to treatment. Literature is sparse, and only a handful of case reports are available to guide treatment decisions. Typical first line treatment options include topical and intralesional steroids, topical pimecrolimus, and cryotherapy. Resistant cases have been treated with cyclosporine, systemic steroids, antimalarials, and oral retinoids. In particular, acitretin and isotretinoin have shown success in three cases. However, these medications can have side effects and require frequent lab monitoring. We present a case of a 47-year-old woman with bilateral forearm lesions consistent with annular elastolytic giant cell granuloma who was successfully treated with topical tretinoin.

J Drugs Dermatol. 2017;16(7):699-700.

Debris-less method and apparatus for forming apertures in hollow metallic articles

DOEpatents

Jordan, C.L.; Chodelka, E.J.

1980-06-24

This invention is a method for forming an aperture in a wall of a hollow metallic article without introducing metallic debris therein. In a typical operation, an annular groove is formed in an exterior portion of the wall. The groove defines an annular wall segment, and the bottom of the groove is shaped to slope downwardly away from the segment to form a tapered annular web which connects the segment to the wall. Any suitable coupling is attached to the outer face of the segment, as by welding. Pull then is applied to the coupling to effect circumferential breakage of the web, thus forming a removable single-piece wall fragment consisting of the web and segment. The fragment and the coupling member attached thereto then are removed from the wall.

Wind Generated Rogue Waves in an Annular Wave Flume.

PubMed

Toffoli, A; Proment, D; Salman, H; Monbaliu, J; Frascoli, F; Dafilis, M; Stramignoni, E; Forza, R; Manfrin, M; Onorato, M

2017-04-07

We investigate experimentally the statistical properties of a wind-generated wave field and the spontaneous formation of rogue waves in an annular flume. Unlike many experiments on rogue waves where waves are mechanically generated, here the wave field is forced naturally by wind as it is in the ocean. What is unique about the present experiment is that the annular geometry of the tank makes waves propagating circularly in an unlimited-fetch condition. Within this peculiar framework, we discuss the temporal evolution of the statistical properties of the surface elevation. We show that rogue waves and heavy-tail statistics may develop naturally during the growth of the waves just before the wave height reaches a stationary condition. Our results shed new light on the formation of rogue waves in a natural environment.

Enhanced optical transmission through double-overlapped annular aperture array

NASA Astrophysics Data System (ADS)

Wang, Chaonan; Bai, Ming; Jin, Ming

2012-07-01

In this paper, transmission properties through an array of concentric or eccentric double-overlapped annular apertures (CDOAAs or EDOAAs) are investigated. It is demonstrated that local surface plasmon-assisted TE11-like modes in CDOAAs exhibit a blue shift with the increasing overlapped factor. For EDOAAs with asymmetric annular apertures in both directions, a new resonant peak can be excited at a larger wavelength using linearly polarised light, which corresponds to extreme field localisation around the narrowest gap attributed to the gap plasmons' excitation and is quite sensitive to the offset of the eccentric centre island. These properties provide a possible method to achieve multiplexed and tunable wavelength selection using different local surface plasmon resonances and are of significant potential applicable value to the designing of tunable optical devices.

Micro-Fresnel Zone Plate Optical Devices Using Densely Accumulated Ray Points

NASA Technical Reports Server (NTRS)

Choi, Sang H. (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

2011-01-01

An embodiment generally relates to an optical device suitable for use with an optical medium for the storage and retrieval of data. The optical device includes an illumination means for providing a beam of optical radiation of wavelength .lamda. and an optical path that the beam of optical radiation follows. The optical device also includes a diffractive optical element defined by a plurality of annular sections. The plurality of annular sections having a first material alternately disposed with a plurality of annular sections comprising a second material. The diffractive optical element generates a plurality of focal points and densely accumulated ray points with phase contrast phenomena and the optical medium is positioned at a selected focal point or ray point of the diffractive optical element.

Multi-cylinder hot gas engine

DOEpatents

Corey, John A.

1985-01-01

A multi-cylinder hot gas engine having an equal angle, V-shaped engine block in which two banks of parallel, equal length, equally sized cylinders are formed together with annular regenerator/cooler units surrounding each cylinder, and wherein the pistons are connected to a single crankshaft. The hot gas engine further includes an annular heater head disposed around a central circular combustor volume having a new balanced-flow hot-working-fluid manifold assembly that provides optimum balanced flow of the working fluid through the heater head working fluid passageways which are connected between each of the cylinders and their respective associated annular regenerator units. This balanced flow provides even heater head temperatures and, therefore, maximum average working fluid temperature for best operating efficiency with the use of a single crankshaft V-shaped engine block.

Method of electroforming a rocket chamber

NASA Technical Reports Server (NTRS)

Fortini, A. (Inventor)

1974-01-01

A transpiration cooled rocket chamber is made by forming a porous metal wall on a suitably shaped mandrel. The porous wall may be made of sintered powdered metal, metal fibers sintered on the mandrel or wires woven onto the mandrel and then sintered to bond the interfaces of the wires. Intersecting annular and longitudinal ribs are then electroformed on the porous wall. An interchamber wall having orifices therein is then electroformed over the annular and longitudinal ribs. Parallel longitudinal ribs are then formed on the outside surface of the interchamber wall after which an annular jacket is electroformed over the parallel ribs to form distribution passages therewith. A feed manifold communicating with the distribution passages may be fabricated and welded to the rocket chamber or the feed manifold may be electroformed in place.

Dual annular rotating "windowed" nuclear reflector reactor control system

DOEpatents

Jacox, Michael G.; Drexler, Robert L.; Hunt, Robert N. M.; Lake, James A.

1994-01-01

A nuclear reactor control system is provided in a nuclear reactor having a core operating in the fast neutron energy spectrum where criticality control is achieved by neutron leakage. The control system includes dual annular, rotatable reflector rings. There are two reflector rings: an inner reflector ring and an outer reflector ring. The reflectors are concentrically assembled, surround the reactor core, and each reflector ring includes a plurality of openings. The openings in each ring are capable of being aligned or non-aligned with each other. Independent driving means for each of the annular reflector rings is provided so that reactor criticality can be initiated and controlled by rotation of either reflector ring such that the extent of alignment of the openings in each ring controls the reflection of neutrons from the core.

A contoured gap coaxial plasma gun with injected plasma armature.

PubMed

Witherspoon, F Douglas; Case, Andrew; Messer, Sarah J; Bomgardner, Richard; Phillips, Michael W; Brockington, Samuel; Elton, Raymond

2009-08-01

A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 microg of plasma with density above 10(17) cm(-3) to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 microg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

Microstructure study of a severely plastically deformed Mg-Zn-Y alloy by application of low angle annular dark field diffraction contrast imaging.

PubMed

Basha, Dudekula Althaf; Rosalie, Julian M; Somekawa, Hidetoshi; Miyawaki, Takashi; Singh, Alok; Tsuchiya, Koichi

2016-01-01

Microstructural investigation of extremely strained samples, such as severely plastically deformed (SPD) materials, by using conventional transmission electron microscopy techniques is very challenging due to strong image contrast resulting from the high defect density. In this study, low angle annular dark field (LAADF) imaging mode of scanning transmission electron microscope (STEM) has been applied to study the microstructure of a Mg-3Zn-0.5Y (at%) alloy processed by high pressure torsion (HPT). LAADF imaging advantages for observation of twinning, grain fragmentation, nucleation of recrystallized grains and precipitation on second phase particles in the alloy processed by HPT are highlighted. By using STEM-LAADF imaging with a range of incident angles, various microstructural features have been imaged, such as nanoscale subgrain structure and recrystallization nucleation even from the thicker region of the highly strained matrix. It is shown that nucleation of recrystallized grains starts at a strain level of revolution [Formula: see text] (earlier than detected by conventional bright field imaging). Occurrence of recrystallization of grains by nucleating heterogeneously on quasicrystalline particles is also confirmed. Minimizing all strain effects by LAADF imaging facilitated grain size measurement of [Formula: see text] nm in fully recrystallized HPT specimen after [Formula: see text].

A cycloidal wobble motor driven by shape memory alloy wires

NASA Astrophysics Data System (ADS)

Hwang, Donghyun; Higuchi, Toshiro

2014-05-01

A cycloidal wobble motor driven by shape memory alloy (SMA) wires is proposed. In realizing a motor driving mechanism well known as a type of reduction system, a cycloidal gear mechanism is utilized. It facilitates the achievement of bidirectional continuous rotation with high-torque capability, based on its high efficiency and high reduction ratio. The applied driving mechanism consists of a pin/roller based annular gear as a wobbler, a cycloidal disc as a rotor, and crankshafts to guide the eccentric wobbling motion. The wobbling motion of the annular gear is generated by sequential activation of radially phase-symmetrically placed SMA wires. Consequently the cycloidal disc is rotated by rolling contact based cycloidal gearing between the wobbler and the rotor. In designing the proposed motor, thermomechanical characterization of an SMA wire biased by extension springs is experimentally performed. Then, a simplified geometric model for the motor is devised to conduct theoretical assessment of design parametric effects on structural features and working performance. With consideration of the results from parametric analysis, a functional prototype three-phase motor is fabricated to carry out experimental verification of working performance. The observed experimental results including output torque, rotational speed, bidirectional positioning characteristic, etc obviously demonstrate the practical applicability and potentiality of the wobble motor.

Analysis of Bi Distribution in Epitaxial GaAsBi by Aberration-Corrected HAADF-STEM

NASA Astrophysics Data System (ADS)

Baladés, N.; Sales, D. L.; Herrera, M.; Tan, C. H.; Liu, Y.; Richards, R. D.; Molina, S. I.

2018-04-01

The Bi content in GaAs/GaAs1 - x Bi x /GaAs heterostructures grown by molecular beam epitaxy at a substrate temperature close to 340 °C is investigated by aberration-corrected high-angle annular dark-field techniques. The analysis at low magnification of high-angle annular dark-field scanning transmission electron microscopy images, corroborated by EDX analysis, revealed planar defect-free layers and a non-homogeneous Bi distribution at the interfaces and within the GaAsBi layer. At high magnification, the qHAADF analysis confirmed the inhomogeneous distribution and Bi segregation at the GaAsBi/GaAs interface at low Bi flux and distorted dumbbell shape in areas with higher Bi content. At higher Bi flux, the size of the Bi gathering increases leading to roughly equiaxial Bi-rich particles faceted along zinc blende {111} and uniformly dispersed around the matrix and interfaces. FFT analysis checks the coexistence of two phases in some clusters: a rhombohedral pure Bi (rh-Bi) one surrounded by a zinc blende GaAs1 - x Bi x matrix. Clusters may be affecting to the local lattice relaxation and leading to a partially relaxed GaAsBi/GaAs system, in good agreement with XRD analysis.

High power coaxial ubitron

NASA Astrophysics Data System (ADS)

Balkcum, Adam J.

In the ubitron, also known as the free electron laser, high power coherent radiation is generated from the interaction of an undulating electron beam with an electromagnetic signal and a static periodic magnetic wiggler field. These devices have experimentally produced high power spanning the microwave to x-ray regimes. Potential applications range from microwave radar to the study of solid state material properties. In this dissertation, the efficient production of high power microwaves (HPM) is investigated for a ubitron employing a coaxial circuit and wiggler. Designs for the particular applications of an advanced high gradient linear accelerator driver and a directed energy source are presented. The coaxial ubitron is inherently suited for the production of HPM. It utilizes an annular electron beam to drive the low loss, RF breakdown resistant TE01 mode of a large coaxial circuit. The device's large cross-sectional area greatly reduces RF wall heat loading and the current density loading at the cathode required to produce the moderate energy (500 keV) but high current (1-10 kA) annular electron beam. Focusing and wiggling of the beam is achieved using coaxial annular periodic permanent magnet (PPM) stacks without a solenoidal guide magnetic field. This wiggler configuration is compact, efficient and can propagate the multi-kiloampere electron beams required for many HPM applications. The coaxial PPM ubitron in a traveling wave amplifier, cavity oscillator and klystron configuration is investigated using linear theory and simulation codes. A condition for the dc electron beam stability in the coaxial wiggler is derived and verified using the 2-1/2 dimensional particle-in-cell code, MAGIC. New linear theories for the cavity start-oscillation current and gain in a klystron are derived. A self-consistent nonlinear theory for the ubitron-TWT and a new nonlinear theory for the ubitron oscillator are presented. These form the basis for simulation codes which, along with MAGIC, are used to design a representative 200 MW, 40% efficient, X-band amplifier for linear accelerators and a 1 GW, 21% efficient, S-band oscillator for directed energy. The technique of axial mode profiling in the ubitron cavity oscillator is also proposed and shown to increase the simulated interaction efficiency to 46%. These devices are realizable and their experimental implementation, including electron beam formation and spurious mode suppression techniques, is discussed.

Manufacturing Methods and Technology Application of High Energy Laser Welding Process.

DTIC Science & Technology

1980-08-01

surface appearance and the lowest porosity of the three beam shapes evaluated. Welds made with the pure annular beam resembled a TIG weld in both surface...improper starts and stops when welding with a conventional MIG or TIG process. Figure 16 left and center illustrates cracking due to fast freezing conditions...REPORT RL-82-2 0 MANUFACTURING METHODS AND TECHNOLOGY APPLICATION _OF HIGH ENERGY LASER WELDING PROCESS 0John V. Melonas Structures Directorate, U S

Direct observation of antisite defects in LiCoPO4 cathode materials by annular dark- and bright-field electron microscopy.

PubMed

Truong, Quang Duc; Devaraju, Murukanahally Kempaiah; Tomai, Takaaki; Honma, Itaru

2013-10-23

LiCoPO4 cathode materials have been synthesized by a sol-gel route. X-ray diffraction analysis confirmed that LiCoPO4 was well-crystallized in an orthorhombic structure in the Pmna space group. From the high-resolution transmission electron microscopy (HR-TEM) image, the lattice fringes of {001} and {100} are well-resolved. The HR-TEM image and selected area electron diffraction pattern reveal the highly crystalline nature of LiCoPO4 having an ordered olivine structure. The atom-by-atom structure of LiCoPO4 olivine has been observed, for the first time, using high-angle annular dark-field (HAADF) and annual bright-field scanning transmission electron microscopy. We observed the bright contrast in Li columns in the HAADF images and strong contrast in the ABF images, directly indicating the antisite exchange defects in which Co atoms partly occupy the Li sites. The LiCoPO4 cathode materials delivered an initial discharge capacity of 117 mAh/g at a C/10 rate with moderate cyclic performance. The discharge profile of LiCoPO4 shows a plateau at 4.75 V, revealing its importance as a potentially high-voltage cathode. The direct visualization of atom-by-atom structure in this work represents important information for the understanding of the structure of the active cathode materials for Li-ion batteries.