Multiple internal seal ring micro-electro-mechanical system vacuum packaging method

NASA Technical Reports Server (NTRS)

Hayworth, Ken J. (Inventor); Yee, Karl Y. (Inventor); Shcheglov, Kirill V. (Inventor); Bae, Youngsam (Inventor); Wiberg, Dean V. (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)

2008-01-01

A Multiple Internal Seal Ring (MISR) Micro-Electro-Mechanical System (MEMS) vacuum packaging method that hermetically seals MEMS devices using MISR. The method bonds a capping plate having metal seal rings to a base plate having metal seal rings by wafer bonding the capping plate wafer to the base plate wafer. Bulk electrodes may be used to provide conductive paths between the seal rings on the base plate and the capping plate. All seals are made using only metal-to-metal seal rings deposited on the polished surfaces of the base plate and capping plate wafers. However, multiple electrical feed-through metal traces are provided by fabricating via holes through the capping plate for electrical connection from the outside of the package through the via-holes to the inside of the package. Each metal seal ring serves the dual purposes of hermetic sealing and providing the electrical feed-through metal trace.

Evidence that Arrhenius high-temperature aging behavior for an EPDM o-ring does not extrapolate to lower temperatures

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

Gillen, K.T.; Wise, J.; Celina, M.

1997-09-01

Because of the need to significantly extend the lifetimes of weapons, and because of potential implications of environmental O-ring failure on degradation of critical internal weapon components, the authors have been working on improved methods of predicting and verifying O-ring lifetimes. In this report, they highlight the successful testing of a new predictive method for deriving more confident lifetime extrapolations. This method involves ultrasensitive oxygen consumption measurements. The material studied is an EPDM formulation use for the environmental O-ring the W88. Conventional oven aging (155 C to 111 C) was done on compression molded sheet material; periodically, samples were removedmore » from the ovens and subjected to various measurements, including ultimate tensile elongation, density and modulus profiles. Compression stress relaxation (CSR) measurements were made at 125 C and 111 C on disc shaped samples (12.7 mm diameter by 6 mm thick) using a Shawbury Wallace Compression Stress Relaxometer MK 2. Oxygen consumption measurements were made versus time, at temperatures ranging from 160 C to 52 C, using chromatographic quantification of the change in oxygen content caused by reaction with the EPDM material in sealed containers.« less

Grease-Resistant O Rings for Joints in Solid Rocket Motors

NASA Technical Reports Server (NTRS)

Harvey, Albert R.; Feldman, Harold

2003-01-01

There is a continuing effort to develop improved O rings for sealing joints in solid-fuel rocket motors. Following an approach based on the lessons learned in the explosion of the space shuttle Challenger, investigators have been seeking O-ring materials that exhibit adequate resilience for effective sealing over a broad temperature range: What are desired are O rings that expand far and fast enough to maintain seals, even when metal sealing surfaces at a joint move slightly away from each other shortly after ignition and the motor was exposed to cold weather before ignition. Other qualities desired of the improved O rings include adequate resistance to ablation by hot rocket gases and resistance to swelling when exposed to hydrocarbon-based greases used to protect some motor components against corrosion. Five rubber formulations two based on a fluorosilicone polymer and three based on copolymers of epichlorohydrin with ethylene oxide were tested as candidate O-ring materials. Of these, one of the epichlorohydrin/ethylene oxide formulations was found to offer the closest to the desired combination of properties and was selected for further evaluation.

Monitoring Snow on ice as Critical Habitat for Ringed Seals

NASA Astrophysics Data System (ADS)

Kelly, B. P.; Moran, J.; Douglas, D. C.; Nghiem, S. V.

2007-12-01

Ringed seals are the primary prey of polar bears, and they are found in all seasonally ice covered seas of the northern hemisphere as well as in several freshwater lakes. The presence of snow covered sea ice is essential for successful ringed seal reproduction. Ringed seals abrade holes in the ice allowing them to surface and breathe under the snow cover. Where snow accumulates to sufficient depths, ringed seals excavate subnivean lairs above breathing holes. They rest, give birth, and nurse their young in those lairs. Temperatures within the lairs remain within a few degrees of freezing, well within the zone of thermal neutrality for newborn ringed seals, even at ambient temperatures of -30° C. High rates of seal mortality have been recorded when early snow melt caused lairs to collapse exposing newborn seals to predators and to subsequent extreme cold events. As melt onset dates come earlier in the Arctic Ocean, ringed seal populations (and the polar bears that depend upon them) will be increasingly challenged. We determined dates of lair abandonment by ringed seals fitted with radio transmitters in the Beaufort Sea (n = 60). We compared abandonment dates to melt onset dates measured in the field, as well as estimated dates derived from active (Ku-band backscatter) and passive (SSM/I) microwave satellite imagery. Date of snow melt significantly improved models of environmental influences on the timing of lair abandonment. We used an algorithm based on multi-channel means and variances of passive microwave data to detect melt onset dates. Those melt onset dates predicted the date of lair abandonment ± 3 days (r 2 = 0.982, p = 0.001). The predictive power of passive microwave proxies combined with their historical record suggest they could serve to monitor critical changes to ringed seal habitat.

SRB attach ring phenolic TPS fishtail seal evaluation tests

NASA Technical Reports Server (NTRS)

Karu, Z. S.

1982-01-01

The SRB attach ring is thermally protected with layered phenolic cloth fairings that are fastened to the ring. The gap between the fairings and the motor case is closed off with a rubber seal of a fishtail cross sectional shape bonded to the phenolic. On both the STS-1 and STS-2 flights this gap was discovered to vary anywhere from an intended gap of 0.375 in. to an actual measured gap of 0.60 in. due to tolerances. Tests were conducted with and without a 0.25 in. thick cork shim placed under the seal with a 0.60 in. gap under the phenolic TPS to determine and compare the performance of the seal in the two different configurations. To alleviate the difficult and costly procedure of installing the cork shim under the seal, especially after phenolic TPS mounting on the attach ring, large fishtail seals of idential Elder gray silicon material and two different hardnesses were tested. A similar matrix of tests was conducted with this new large fishtail seal, and seals with both type hardnesses performed well regardless of whether or not the seal was bonded in the phenolic at the front of the seal groove. Similar results had been obtained with the original small fishtail seal which performed adequately with the 0.25 in. cork shim under it.

Sealing a Loosely Fitting Valve Assembly

NASA Technical Reports Server (NTRS)

Goff, L.; Tellier, G.

1986-01-01

Double-ring seal avoids expense of remachining or redesigning valve parts. Mating fittings on valve sealed by pair of rings - one O-ring and backup ring. Backup ring fills relatively large gap between parts. Prevents softer O-ring from being pushed into and through gap.

Evaluation of soft rubber goods. [for use as O-rings, and seals on space shuttle

NASA Technical Reports Server (NTRS)

Merz, P. L.

1974-01-01

The performance of rubber goods suitable for use as O-rings, seals, gaskets, bladders and diaphragms under conditions simulating those of the space shuttle were studied. High reliability throughout the 100 flight missions planned for the space shuttle was considered of overriding importance. Accordingly, in addition to a rank ordering of the selected candidate materials based on prolonged fluid compatibility and sealability behavior, basic rheological parameters (such as cyclic hysteresis, stress relaxation, indicated modulus, etc.) were determined to develop methods capable of predicting the cumulative effect of these multiple reuse cycles.

Collar nut and thrust ring

DOEpatents

Lowery, Guy B.

1991-01-01

A collar nut comprises a hollow cylinder having fine interior threads at one end for threadably engaging a pump mechanical seal assembly and an inwardly depending flange at the other end. The flange has an enlarged portion with a groove for receiving an O-ring for sealing against the intrusion of pumpage from the exterior. The enlarged portion engages a thrust ring about the pump shaft for crushing a hard O-ring, such as a graphite O-ring. The hard O-ring seals the interior of the mechanical seal assembly and pump housing against the loss of lubricants or leakage of pumpage. The fine threads of the hollow cylinder provide the mechanical advantage for crushing the hard O-ring evenly and easily with a hand tool from the side of the collar nut rather than by tightening a plurality of bolts from the end and streamlines the exterior surface of the mechanical seal. The collar nut avoids the spatial requirements of bolt heads at the end of a seal and associated bolt head turbulence.

Thermal Barrier/Seal for Extreme Temperature Applications

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Dunlap, Patrick H., Jr.; Phelps, Jack; Bauer, Paul; Bond, Bruce; McCool, Alex (Technical Monitor)

2002-01-01

Large solid rocket motors, as found on the Space Shuttle, are fabricated in segments for manufacturing considerations, bolted together, and sealed using conventional Viton O-ring seals. Similarly the nine large solid rocket motor nozzles are assembled from several different segments, bolted together, and sealed at six joint locations using conventional O-ring seals. The 5500 F combustion gases are generally kept a safe distance away from the seals by thick layers of phenolic or rubber insulation. Joint-fill compounds, including RTV (room temperature vulcanized compound) and polysulfide filler, are used to fill the joints in the insulation to prevent a direct flow-path to the O-rings. Normally these two stages of protection are enough to prevent a direct flow-path of the 900-psi hot gases from reaching the temperature-sensitive O-ring seals. However, in the current design 1 out of 15 Space Shuttle solid rocket motors experience hot gas effects on the Joint 6 wiper (sacrificial) O-rings. Also worrisome is the fact that joints have experienced heat effects on materials between the RTV and the O-rings, and in two cases O-rings have experienced heat effects. These conditions lead to extensive reviews of the post-flight conditions as part of the effort to monitor flight safety. We have developed a braided carbon fiber thermal barrier to replace the joint fill compounds in the Space Shuttle solid rocket motor nozzles to reduce the incoming 5500 F combustion gas temperature and permit only cool (approximately 100 F) gas to reach the temperature-sensitive O-ring seals. Implementation of this thermal barrier provides more robust, consistent operation with shorter turn around times between Shuttle launches.

Fluorocarbon seal replaces metal piston ring in low density gas environment

NASA Technical Reports Server (NTRS)

Morath, W. D.; Morgan, N. E.

1967-01-01

Reinforced fluorocarbon cupseal, which provides an integral lip-type seal, replaces the metal piston rings in piston-cylinder configurations used in the compression of low density gases. The fluorocarbon seal may be used as cryogenic compressor piston seals.

Viscoelastic analysis of seals for extended service life

NASA Technical Reports Server (NTRS)

Bower, Mark V.

1993-01-01

The space station is being developed for a service life of up to thirty years. As a consequence, the design requirements for the seals to be used are unprecedented. Full scale testing to assure the selected seals can satisfy the design requirements are not feasible. As an alternative, a sub-scale test program (2) has been developed by MSFC to calibrate the analysis tools to be used to certify the proposed design. This research has been conducted in support of the MSFC Integrated Seal Test Program. The ultimate objective of this research is to correlate analysis and test results to qualify the analytical tools which in turn, are to be used to qualify the flight hardware. Seals are simple devices, in wide spread use. The most common type of seal is the O-ring. O-ring seals are typically rings of rubber with a circular cross section. The rings are placed between the surfaces to be sealed, usually in a groove of some design. The particular design may differ based on a number of different factors. This research is focused on O-rings that are staticly compressed by perpendicular clamping forces, commonly referred to as face seals. In this type of seal the O-ring is clamped between the sealing surfaces by loads perpendicular to the circular cross section.

Detection and direction discrimination of single vortex rings by harbour seals (Phoca vitulina).

PubMed

Krüger, Yvonne; Hanke, Wolf; Miersch, Lars; Dehnhardt, Guido

2018-04-25

Harbour seals possess highly sensitive vibrissae that enable them to track hydrodynamic trails left behind by a swimming fish. Most of these trails contain vortex rings as a main hydrodynamic component. They may reveal information about their generator as the trails differ depending on the fish species, the fish's body shape, size and swimming style. In addition, fish generate single vortex rings in diverse natural situations. In this study, the ability of blindfolded stationary harbour seals to detect and analyse single vortex rings regarding directional information has been investigated. In three different behavioural experiments, the animals were trained to respond to single artificially generated vortex rings. The results show that harbour seals are able to respond to a variety of different vortex rings upon vibrissal stimulation. The investigation of the minimum hydrodynamically perceivable angle revealed that it is at least as small as 5.7 deg, which was the smallest adjustable angle. Moreover, harbour seals are capable of analysing the travel direction of a vortex ring perceived by the mystacial vibrissae irrespective of whether the vibrissae were stimulated ipsilaterally or contralaterally. In situations in which no complex hydrodynamic trail is available, it is advantageous for a hunting seal to be able to extract information from a single vortex ring. © 2018. Published by The Company of Biologists Ltd.

Damped flexible seal

DOEpatents

DuBois, Neil J.; Amaral, Antonio M.

1992-10-27

A damped flexible seal assembly for a torpedo isolates the tailcone thereof rom vibrational energy present in the drive shaft assembly. A pair of outside flanges, each of which include an inwardly facing groove and an O-ring constrained therein, provide a watertight seal against the outer non-rotating surface of the drive shaft assembly. An inside flange includes an outwardly-facing groove and an O-ring constrained therein, and provides a watertight seal against the inner surface of the tail cone. Two cast-in-place elastomeric seals provide a watertight seal between the flanges and further provide a damping barrier between the outside flanges and the inside flanges for damping vibrational energy present in the drive shaft assembly before the energy can reach the tailcone through the seal assembly.

Macroscopic anatomy of the heart of the ringed seal (Phoca hispida).

PubMed

Smodlaka, H; Henry, R W; Schumacher, J; Reed, R B

2008-02-01

Anatomical properties of the ringed seal (Phoca hispida) heart and associated blood vessels reveal adaptations related to requirements for diving. Seven adult ringed seals were embalmed and dissected to document the gross anatomical features of the heart. Computed tomography images of the thoracic cavity were taken on one seal prior to dissection. The shape and position of the heart is different from the typical carnivore heart. The most notable difference is its dorsoventral flattened appearance with its right and left sides positioned, respectively, within the thoracic cavity. The long axis of the heart is positioned horizontally, parallel to the sternum. The right ventricle is spacious with thin walls which extend caudally to the apex of the heart such that the apex is comprised of both right and left ventricles. The cusps of the left atrioventricular valve of the ringed seal heart resemble an uninterrupted, circular curtain making it challenging to distinguish the divisions into parietal and septal cusps.

Leak Rate Performance of Silicone Elastomer O-Rings Contaminated with JSC-1A Lunar Regolith Simulant

NASA Technical Reports Server (NTRS)

Oravec, Heather Ann; Daniels, Christopher C.

2014-01-01

Contamination of spacecraft components with planetary and foreign object debris is a growing concern. Face seals separating the spacecraft cabin from the debris filled environment are particularly susceptible; if the seal becomes contaminated there is potential for decreased performance, mission failure, or catastrophe. In this study, silicone elastomer O-rings were contaminated with JSC- 1A lunar regolith and their leak rate performance was evaluated. The leak rate values of contaminated O-rings at four levels of seal compression were compared to those of as-received, uncontaminated, O-rings. The results showed a drastic increase in leak rate after contamination. JSC-1A contaminated O-rings lead to immeasurably high leak rate values for all levels of compression except complete closure. Additionally, a mechanical method of simulant removal was examined. In general, this method returned the leak rate to as-received values.

Butyl rubber O-ring seals: Revision of test procedures for stockpile materials

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

Domeier, L.A.; Wagter, K.R.

1996-12-01

Extensive testing showed little correlation between test slab and O-ring performance. New procedures, comparable to those used with the traditional test slabs, were defined for hardness, compression set, and tensile property testing on sacrificial O-ring specimens. Changes in target performance values were made as needed and were, in one case, tightened to reflect the O-ring performance data. An additional study was carried out on O-ring and slab performance vs cure cycle and showed little sensitivity of material performance to large changes in curing time. Aging and spectra of certain materials indicated that two sets of test slabs from current vendormore » were accidently made from EPDM rather than butyl rubber. Random testing found no O-rings made from EPDM. As a result, and additional spectroscope test will be added to the product acceptance procedures to verify the type of rubber compound used.« less

REVIEW OF AGING DATA ON EPDM O-RINGS IN THE H1616 SHIPPING PACKAGE

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

Skidmore, E.

Currently, all H1616 shipping package containers undergo annual re-verification testing, including containment vessel leak testing to verify leak-tightness (<1 x 10{sup -7} ref cc/sec air) as per ANSI N14.5. The purpose of this literature review is to supplement aging studies currently being performed by SRNL on the EPDM O-rings to provide the technical basis for extending annual re-verification testing for the H1616 shipping package and to predict the life of the seals at bounding service conditions. The available data suggest that the EPDM O-rings can retain significant mechanical properties and sealing force at or below bounding service temperatures (169 Fmore » or 76 C) beyond the 1 year maintenance period. Interpretation of available data suggests that a service life of at least 2 years and potentially 4-6 years may be possible at bounding temperatures. Seal lifetimes at lower, more realistic temperatures will likely be longer. Being a hydrocarbon elastomer, EPDM O-rings may exhibit an inhibition period due to the presence of antioxidants. Once antioxidants are consumed, mechanical properties and seal performance could decline at a faster rate. Testing is being performed to validate the assumptions outlined in this report and to assess the long-term performance of O-ring seals under actual service conditions.« less

77 FR 20773 - Endangered and Threatened Species; Proposed Threatened Status for Subspecies of the Ringed Seal

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-06

...-XZ59 Endangered and Threatened Species; Proposed Threatened Status for Subspecies of the Ringed Seal... conducted special independent peer review of the December 2010 status review report of the ringed seal... ochotensis), and Ladoga (Phoca hispida ladogensis) subspecies of ringed seals as threatened (75 FR 77476). On...

Amphibious hearing in ringed seals (Pusa hispida): underwater audiograms, aerial audiograms and critical ratio measurements.

PubMed

Sills, Jillian M; Southall, Brandon L; Reichmuth, Colleen

2015-07-01

Ringed seals (Pusa hispida) are semi-aquatic marine mammals with a circumpolar Arctic distribution. In this study, we investigate the amphibious hearing capabilities of ringed seals to provide auditory profiles for this species across the full range of hearing. Using psychophysical methods with two trained ringed seals, detection thresholds for narrowband signals were measured under quiet, carefully controlled environmental conditions to generate aerial and underwater audiograms. Masked underwater thresholds were measured in the presence of octave-band noise to determine critical ratios. Results indicate that ringed seals possess hearing abilities comparable to those of spotted seals (Phoca largha) and harbor seals (Phoca vitulina), and considerably better than previously reported for ringed and harp seals. Best sensitivity was 49 dB re. 1 µPa (12.8 kHz) in water, and -12 dB re. 20 µPa (4.5 kHz) in air, rivaling the acute hearing abilities of some fully aquatic and terrestrial species in their respective media. Critical ratio measurements ranged from 14 dB at 0.1 kHz to 31 dB at 25.6 kHz, suggesting that ringed seals--like other true seals--can efficiently extract signals from background noise across a broad range of frequencies. The work described herein extends similar research on amphibious hearing in spotted seals recently published by the authors. These parallel studies enhance our knowledge of the auditory capabilities of ice-living seals, and inform effective management strategies for these and related species in a rapidly changing Arctic environment. © 2015. Published by The Company of Biologists Ltd.

High-Pressure Hot-Gas Self-Acting Floating Ring Shaft Seal for Liquid Rocket Turbopumps. [tapered bore seals

NASA Technical Reports Server (NTRS)

Burcham, R. E.; Diamond, W. A.

1980-01-01

Design analysis, detail design, fabrication, and experimental evaluation was performed on two self acting floating ring shaft seals for a rocket engine turbopump high pressure 24132500 n/sq m (3500 psig) hot gas 533 K 9500 F) high speed 3142 rad/sec (30000 rmp) turbine. The initial design used Rayleigh step hydrodynamic lift pads to assist in centering the seal ring with minimum rubbing contact. The final design used a convergent tapered bore to provide hydrostatic centering force. The Rayleigh step design was tested for 107 starts and 4.52 hours total. The leakage was satisfactory; however, the design was not acceptable due to excessive wear caused by inadequate centering force and failure of the sealing dam caused by erosion damage. The tapered bore design was tested for 370 starts and 15.93 hours total. Satisfactory performance for the required life of 7.5 hours per seal was successfully demonstrated.

Problems and criteria of quality improvement in end face mechanical seal rings through technological methods

NASA Astrophysics Data System (ADS)

Tarelnik, V.; Belous, A.; Antoszewski, B.; Zukov, A.

2017-08-01

In this paper are presented the recommendations for material’s selections of the mechanical seals rings and basic productive and operating requirements. The system of a directional selection of technology that ensures the required quality of working surfaces of the mechanical seals rings covers their entire life cycle. The mathematical frictional model is proposed as an instrument for calculating a linear and weighing abrasion of the mechanical seals rings and helps to improve selection’s criteria and the most rational method of strengthening.

Caps Seal Boltholes On Vacuum-System Flanges

NASA Technical Reports Server (NTRS)

Roman, Robert F.

1993-01-01

Sealing caps devised for boltholes on vacuum-system flanges. Used in place of leak-prone gaskets, and provide solid metal-to-metal interfaces. Each sealing cap contains square-cut circular groove in which O-ring placed. Mounted on studs protruding into access ports, providing positive seal around each bolthole. Each cap mates directly with surface of flange, in solid metal-to-metal fit, with O-ring completely captured in groove. Assembly immune to misalignment, leakage caused by vibration, and creeping distortion caused by weight of port. O-ring material chosen for resistance to high temperature; with appropriate choice of material, temperature raised to as much as 315 degrees C.

High-pressure cryogenic seals for pressure vessels

NASA Technical Reports Server (NTRS)

Buggele, A. E.

1977-01-01

This investigation of the problems associated with reliably containing gaseous helium pressurized to 1530 bars (22 500 psi) between 4.2 K and 150 K led to the following conclusions: (1) common seal designs used in existing elevated-temperature pressure vessels are unsuitable for high-pressure cryogenic operation, (2) extrusion seal-ring materials such as Teflon, tin, and lead are not good seal materials for cryogenic high-pressure operation; and (3) several high-pressure cryogenic seal systems suitable for large-pressure vessel applications were developed; two seals required prepressurization, and one seal functioned repeatedly without any prepressurization. These designs used indium seal rings, brass or 304 stainless-steel anvil rings, and two O-rings of silicone rubber or Kel-F.

Persistent organic pollutants in Alaskan ringed seal (Phoca hispida) and walrus (Odobenus rosmarus) blubber

USGS Publications Warehouse

Kucklick, John R.; Krahn, Margaret M.; Becker, Paul R.; Porter, Barbara J.; Schantz, Michele M.; York, Geoffrey S.; O'Hara, Todd M.; Wise, Stephen A.

2006-01-01

Since 1987, the Alaska Marine Mammal Tissue Archival Project (AMMTAP) has collected tissues from 18 marine mammal species. Specimens are archived in the National Institute of Standards and Technology's National Biomonitoring Specimen Bank (NIST-NBSB). AMMTAP has collected blubber, liver and/or kidney specimens from a number of ringed seals (Phoca hispida) from the areas near Nome and Barrow, Alaska and walruses (Odobenus rosmarus) from several locations in the Bering Sea. Thirty-three ringed seal and 15 walrus blubber samples from the NIST-NBSB were analyzed for persistent organic pollutants (POPs). The compounds determined included PCBs (28 congeners or congener groups), DDT and related compounds, hexachlorobenzene (HCB), hexachlorocyclohexane isomers (HCHs), chlordanes, dieldrin, and mirex. POP concentrations in ringed seal blubber were significantly higher in Barrow than in Nome when statistically accounting for the interaction of age and gender; HCB, however, was not statistically different between the two locations. Unlike males, POP concentrations and age were not significantly correlated in females probably as a result of lactational loss. POP concentrations in walrus blubber were lower than in ringed seal blubber for ΣPCBs, chlordanes, and HCHs, but higher for dieldrin and mirex. POP concentrations in ringed seals and walrus from Alaska provide further evidence that the western Arctic tends to have lower or similar POP concentrations compared to the eastern Canadian Arctic.

Macroscopic Anatomy of the Saimaa Ringed Seal (Phoca hispida saimensis) Lower Respiratory Tract.

PubMed

Laakkonen, Juha; Jernvall, Jukka

2016-04-01

We studied the macroscopic anatomy of the lower respiratory tract of the endangered Saimaa ringed seal (Phoca hispida saimensis). Examination of one adult and one young individual found dead showed that trachea had 85 and 86 complete cartilage rings. The adjacent cartilages exhibited very few random anastomoses. There was variation in the confirmation of the trachea between the cranial and caudal part of the trachea. The right lung was divided by partly incomplete inter-lobar fissures into cranial, middle, caudal, and accessory lobes. The left lung consisted of cranial, middle, and caudal lobes. The lungs were characterized by a high amount of interlobular connective tissue. Silicone casts were prepared of the two specimens to visualize the tracheobronchial branching which was similar to that of marine ringed seals but in the Saimaa ringed seal the right middle lobar bronchus originated at the same level as the accessory lobar bronchus. © 2016 Wiley Periodicals, Inc.

Persistent organochlorine pollutants in ringed seals and polar bears collected from northern Alaska

USGS Publications Warehouse

Kucklick, J.R.; Struntz, W.D.J.; Becker, P.R.; York, G.W.; O'Hara, T. M.; Bohonowych, J.E.

2002-01-01

Blubber samples from ringed seal (Phoca hispida; n=8) and polar bear subcutaneous fat (Ursus maritimus; n=5) were collected near Barrow, Alaska in 1996 as part of the Alaska Marine Mammal Tissue Archival Project (AMMTAP) and retained in the National Biomonitoring Specimen Bank at the National Institute of Standards and Technology in Gaithersburg, Maryland (USA). The samples were analyzed for a variety of persistent organochlorine pollutants (POPs) including polychlorinated biphenyls (PCBs), hexachlorocyclohexanes (HCHs), chlordane and metabolites, hexachlorobenzene (HCB) and DDTs and metabolites. The geometric mean, on a wet mass basis, of ??PCBs (sum of 29 congeners and congener groups) were 732??282 ng/g (1 S.D.) in seals and 3395??1442 ng/g in polar bears. The geometric mean of ??DDTs, ??HCHs (??-, ??- and ??- HCH) and HCB concentrations (wet mass basis) in seals and bears were 562??261 ng/g vs. 74.8??39 ng/g, 380??213 ng/g vs. 515 ng/g, and 17.4??10.1 ng/g vs. 183??153 ng/g, respectively. The geometric mean sum of chlordane (??chlordane, sum of cis- and trans-chlordane, cis- and trans-nonachlor, oxychlordane and heptachlor epoxide) and dieldrin concentrations in ringed seals and polar bears were 753??617 ng/g vs. 720??315 ng/g and 38.6??22.8 ng/g vs. 130??65 ng/g, respectively. Apparent bioaccumulation factors (polar bear/ringed seal POP concentrations) were lower in the animals sampled near Barrow, Alaska than in those from locations in the Canadian Arctic. This suggests that polar bears are also preying on marine mammals from lower trophic levels than the ringed seals with correspondingly lower organochlorine levels, such as bowhead whale carcasses. PCB congener patterns in the samples demonstrated the metabolism of certain PCB congeners in the polar bear relative to the ringed seal in agreement with previous studies. Regional comparisons of animals collected in Alaska and Arctic Canada are presented. Copyright ?? 2002 Elsevier Science B.V.

Effect of temperature and gap opening rate on the resiliency of candidate solid rocket booster O-ring materials

NASA Technical Reports Server (NTRS)

Lach, Cynthia L.

1992-01-01

In the redesign of the Space Shuttle solid rocket motor following the Challenger accident, the field and nozzle-to-case joints were designed to minimize gap opening caused by internal motor pressurization during ignition. The O-ring seals and glands for these joints were designed both to accommodate structural deflections and to promote pressure assisted sealing. The resiliency behavior of several candidate O-ring materials was evaluated for the effects of temperature and gap opening rates. The performance of three of the elastomeric materials was tested under the specific redesign gap opening requirement. Dynamic flexure conditions unique to launch produce low frequency vibrations in the gap opening. The effect of these vibrations on the ability of the O-ring to maintain contact with the sealing surface was addressed. The resiliency of the O-ring materials was found to be extremely sensitive to variations in temperature and gap opening rate. The top three elastomeric materials tracked the simulated solid rocket booster (SRB) field joint deflection at 75 and 120 F. The external tank/SRB attach strut load vibrations had a negligible effect on the ability of the O-ring to track the simulated SRB field joint deflection.

Feasibility Assessment of Thermal Barrier Seals for Extreme Transient Temperatures

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Dunlap, Patrick H., Jr.

1998-01-01

The assembly joints of modem solid rocket motor cases are generally sealed using conventional O-ring type seals. The 5500+ F combustion gases produced by rocket motors are kept a safe distance away from the seals by thick layers of phenolic insulation. Special compounds are used to fill insulation gaps leading up to the seals to prevent a direct flowpath to them. Design criteria require that the seals should not experience torching or charring during operation, or their sealing ability would be compromised. On limited occasions, NASA has observed charring of the primary O-rings of the Space Shuttle solid rocket nozzle assembly joints due to parasitic leakage paths opening up in the gap-fill compounds during rocket operation. NASA is investigating different approaches for preventing torching or charring of the primary O-rings. One approach is to implement a braided rope seal upstream of the primary O-ring to serve as a thermal barrier that prevents the hot gases from impinging on the O-ring seals. This paper presents flow, resiliency, and thermal resistance for several types of NASA rope seals braided out of carbon fibers. Burn tests were performed to determine the time to burn through each of the seals when exposed to the flame of an oxyacetylene torch (5500 F), representative of the 5500 F solid rocket motor combustion temperatures. Rope seals braided out of carbon fibers endured the flame for over six minutes, three times longer than solid rocket motor burn time. Room and high temperature flow tests are presented for the carbon seals for different amounts of linear compression. Room temperature compression tests were performed to assess seal resiliency and unit preloads as a function of compression. The thermal barrier seal was tested in a subscale "char" motor test in which the seal sealed an intentional defect in the gap insulation. Temperature measurements indicated that the seal blocked 2500 F combustion gases on the upstream side with very little temperature

Design improvement of a pump wear ring labyrinth seal

NASA Technical Reports Server (NTRS)

Rhode, David L.; Morrison, G. L.; Ko, S. H.; Waughtal, S. P.

1987-01-01

The investigation was successful in obtaining two improved designs for the impeller wear ring seal of the liquid hydrogen turbopump of interest. A finite difference computer code was extensively used in a parametric computational study in determining a cavity configuration with high flow resistance due to turbulence dissipation. These two designs, along with that currently used, were fabricated and tested. The improved designs were denoted Type O and Type S. The measurements showed that Type O and Type S given 67 and 30 percent reduction in leakage over the current design, respectively. It was found that the number of cavities, the step height and the presence of a small stator groove are quite important design features. Also, the tooth thickness is of some significance. Finally, the tooth height and an additional large cavity cut out from the stator (upstream of the step) are of negligible importance.

Analysis of organochlorine compounds and extractable organic halogen in three subspecies of ringed seal from northeast Europe

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

Kostamo, A.; Medvedev, N.; Pellinen, J.

2000-04-01

Organochlorine compounds in blubber samples of the ringed seal (Phoca hispida saimensis, P. H. ladogensis, and P. h. hispida) were analyzed in order to estimate the state of pollution in three different water areas in Northeast Europe, namely, Lake Saimaa in Finland, Lake Lodoga, and the White Sea in Russia. Geographic differences in concentrations and in relative concentrations of tri- and tetrachlorocymenes, hexachlorobenzene, {alpha}-HCH, {beta}-HCH, {gamma}-HCH (Lindane), seven polychlorinated biphenyl (PCB) congeners, and p,p{prime}-DDT and its metabolites in ringed seals were compared. Concentrations of chlorinated hydrocarbons varied between the water areas. The highest concentrations were found in Saimaa ringed seals,more » followed by Lodaga ringed seals, and the lowest concentrations were detected in ringed seals from the White Sea. Extractable organic halogen (EOX) concentrations in blubber were also analyzed. The concentrations showed a geographic trend similar to those for the individual compounds identified. In Lakes Ladoga and Saimaa, the concentrations of EOX and chlorinated hydrocarbons in the blubber were dependent on the age and sex of the seals, but no such relationship was observed in samples from the White Sea.« less

Physical characteristic and irritation index of Syzigium aromaticum essential oil in O/W and W/O creams

NASA Astrophysics Data System (ADS)

Safriani, R.; Sugihartini, N.; Yuliani, S.

2017-11-01

Essential oil of Syzigium aromaticum has been formulated in O/W and W/O creams as anti-inflammatory dosage form. The purpose of this study was to evaluate the physical characteristic and irritation index of S. aromaticum essential oil in O/W and W/O creams. The creams were made by fusion method. The creams then were evaluated the physical characteristic including pH, viscosity, spreadability and adhesivity. The irritation index was obtained by irritation skin test in male rabbit. The results showed that the W/O and O/W creams have the value of pH: 6.3 and 6.27; spreadability: 3,18 and 4.17 cm2; adhesivity: 5.59 and 0.07 minutes; viscosity: 4.43 and 2.88 Pa.S, respectively. The irritation test showed that the control enhancer caused mild irritation in both of W/O and O/W creams. These findings indicated that type of cream might influence the physical characteristic and irritation index of S. aromaticum essential oil cream.

Structure reliability design and analysis of support ring for cylinder seal

NASA Astrophysics Data System (ADS)

Minmin, Zhao

2017-09-01

In this paper, the general reliability design process of the cross-sectional dimension of the support ring is introduced, which is used for the cylinder sealing. Then, taking a certain section shape support ring as an example, the every size parameters of section are determined from the view point of reliability design. Last, the static strength and reliability of the support ring are analyzed to verify the correctness of the reliability design result.

Design analysis of a self-acting spiral-groove ring seal for counter-rotating shafts

NASA Technical Reports Server (NTRS)

Dirusso, E.

1983-01-01

A self-acting spiral groove inter-shaft ring seal of nominal 16.33 cm (6.43 in.) diameter for sealing fan bleed air between counter-rotating hafts in advanced turbofan engines was analyzed. The analysis focused on the lift force characteristics of the spiral grooves. A NASA Lewis developed computer program for predicting the performance of gas lubricated face seals was used to optimize the spiral groove geometry to produce maximum lift force. Load capacity curves (lift force as function of film thickness) were generated for four advanced turbofan engine operating conditions at relative seal speeds ranging from 17,850 to 29,800 rpm, sealed air pressures from 6 to 42 N/sq cm (9 to 60 psi) absolute and temperatures from 95 deg to 327 C (203 deg to 620 F). The relative seal sliding speed range was 152 to 255 m/sec (500 to 836 ft/sec). The analysis showed that the spiral grooves are capable of producing sufficient lift force such that the ring seal will operate in a noncontacting mode over the operating range of typical advanced turbofan engines.

Cold cathodes for sealed off CO2 lasers

NASA Technical Reports Server (NTRS)

Hochuli, U. E.; Sciacca, T. P.; Hurt, C. R.

1973-01-01

Experimental results of a group of theoretically selected cold cathode materials are presented. These tests indicate Ag-CuO, Cu, and Pt-Cu as three new cold cathode materials for sealed-off CO2 lasers. The power output of a test laser with an Ag-CuO cathode and a gas volume of only 50 cu cm varied from 0.72 W to 1.1 W at 3000 hours and still yields 0.88 W after 8000 hours. Gas discharge tubes with Cu cathodes and a volume of 25 cu cm yield lifetimes in excess of 10,000 hours. Gas analysis results, obtained from a similar tube over a period of 3000 hours, look most promising. A Pt-Cu alloy cathode shows an extremely promising V-I characteristic over a period of 2800 hours.

Mechanical seal assembly

DOEpatents

Kotlyar, Oleg M.

2001-01-01

An improved mechanical seal assembly is provided for sealing rotating shafts with respect to their shaft housings, wherein the rotating shafts are subject to substantial axial vibrations. The mechanical seal assembly generally includes a rotating sealing ring fixed to the shaft, a non-rotating sealing ring adjacent to and in close contact with the rotating sealing ring for forming an annular seal about the shaft, and a mechanical diode element that applies a biasing force to the non-rotating sealing ring by means of hemispherical joint. The alignment of the mechanical diode with respect to the sealing rings is maintained by a series of linear bearings positioned axially along a desired length of the mechanical diode. Alternative embodiments include mechanical or hydraulic amplification components for amplifying axial displacement of the non-rotating sealing ring and transferring it to the mechanical diode.

Mechanical seal assembly

DOEpatents

Kotlyar, Oleg M.

2002-01-01

An improved mechanical seal assembly is provided for sealing rotating shafts with respect to their shaft housings, wherein the rotating shafts are subject to substantial axial vibrations. The mechanical seal assembly generally includes a rotating sealing ring fixed to the shaft, a non-rotating sealing ring adjacent to and in close contact with the rotating sealing ring for forming an annular seal about the shaft, and a mechanical diode element that applies a biasing force to the non-rotating sealing ring by means of hemispherical joint. The alignment of the mechanical diode with respect to the sealing rings is maintained by a series of linear bearings positioned axially along a desired length of the mechanical diode. Alternative embodiments include mechanical or hydraulic amplification components for amplifying axial displacement of the non-rotating sealing ring and transfering it to the mechanical diode.

STATUS REPORT FOR AGING STUDIES OF EPDM O-RING MATERIAL FOR THE H1616 SHIPPING PACKAGE

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

Stefek, T.; Daugherty, W.; Skidmore, E.

This is an interim status report for tasks carried out per Task Technical Plan SRNL-STI-2011-00506. A series of tasks/experiments are being performed at the Savannah River National Laboratory to monitor the aging performance of ethylene propylene diene monomer (EPDM) Orings used in the H1616 shipping package. The data will support the technical basis to extend the annual maintenance of the EPDM O-rings in the H1616 shipping package and to predict the life of the seals at bounding service conditions. Current expectations are that the O-rings will maintain a seal at bounding normal temperatures in service (152 F) for at leastmore » 12 months. The baseline aging data review suggests that the EPDM O-rings are likely to retain significant mechanical properties and sealing force at bounding service temperatures to provide a service life of at least 2 years. At lower, more realistic temperatures, longer service life is likely. Parallel compression stress relaxation and vessel leak test efforts are in progress to further validate this assessment and quantify a more realistic service life prediction. The H1616 shipping package O-rings were evaluated for baseline property data as part of this test program. This was done to provide a basis for comparison of changes in material properties and performance parameters as a function of aging. This initial characterization was limited to physical and mechanical properties, namely hardness, thickness and tensile strength. These properties appear to be consistent with O-ring specifications. Three H1616-1 Containment Vessels were placed in test conditions and are aging at temperatures ranging from 160 to 300 F. The vessels were Helium leak-tested initially and have been tested at periodic intervals after cooling to room temperature to determine if they meet the criterion of leaktightness defined in ANSI standard N14.5-97 (< 1E-07 std cc air/sec at room temperature). To date, no leak test failures have occurred. The cumulative time

Intestinal helminths of a landlocked ringed seal (Phoca hispida saimensis) population in eastern Finland.

PubMed

Sinisalo, Tuula; Kunnasranta, Mervi; Valtonen, E Tellervo

2003-09-01

A small, landlocked, endangered ringed seal (Phoca hispida saimensis) population lives as a postglacial relict in Lake Saimaa in eastern Finland. In this study, the intestinal metazoans were examined from a total of 61 Saimaa seals found dead from 1981 to 2001. The helminth fauna was very depauperate. Only one acanthocephalan species, Corynosoma magdaleni, has been able to survive during isolation in the freshwater environment. In addition, only two cestode species were found: Diphyllobothrium ditretum and Schistocephalus sp. However, neither of these larvae developed in the ringed seals. As the newborn pups of Saimaa seals are nursed for about 2 months only one of them was infected by C. magdaleni. At 2-5 months the pups harboured worms; however, the mean intensity did not rise distinctively until the seals were adults. C. magdaleni infection increased with increasing age and the abundances were significantly different between the age groups. There was no correlation between the number of parasites and the adult seal body weight; however, seals weighing 36 kg or more carried the majority of the worms. The distribution of the parasites was aggregated; six seals carried 65% (n=1,182) of all worms (total n=1,809) and 26 seals were uninfected. Variation in the number of worms in individual seals may indicate differences in feeding behaviour and in the diet of seals, and/or variation in the immune status of the seals.

The Effect of K and Acidity of NiW-Loaded HY Zeolite Catalyst for Selective Ring Opening of 1-Methylnaphthalene.

PubMed

Lee, You-Jin; Kim, Eun-Sang; Kim, Jeong-Rang; Kim, Joo-Wan; Kim, Tae-Wan; Chae, Ho-Jeong; Kim, Chul-Ung; Lee, Chang-Ha; Jeong, Soon-Yong

2016-05-01

Bi-functional catalysts were prepared using HY zeolites with various SiO2/Al2O3 ratios for acidic function, NiW for metallic function, and K for acidity control. 1-Methylnaphthalene was selected as a model compound for multi-ring aromatics in heavy oil, and its selective ring opening reaction was investigated using the prepared bi-functional catalysts with different levels of acidity in a fixed bed reactor system. In NiW/HY catalysts without K addition, the acidity decreased with the SiO2/Al2O3 mole ratio of the HY zeolite. Ni1.1W1.1/HY(12) catalyst showed the highest acidity but slightly lower yields for the selective ring opening than Ni1.1W1.1/HY(30) catalyst. The acidity of the catalyst seemed to play an important role as the active site for the selective ring opening of 1-methylnaphthalene but there should be some optimum catalyst acidity for the reaction. Catalyst acidity could be controlled between Ni1.1W1.1/HY(12) and Ni1.1W1.1/HY(30) by adding a moderate amount of K to Ni1.1W1.1/HY(12) catalyst. K0.3Ni1.1W1.1/HY(12) catalyst should have the optimum acidity for the selective ring opening. The addition of a moderate amount of K to the NiW/HY catalyst must improve the catalytic performance due to the optimization of catalyst acidity.

Neutral O2 and Ion O2+ Sources from Rings into the Inner Magnetosphere

NASA Astrophysics Data System (ADS)

Elrod, M. K.; Johnson, R. E.; Cassidy, T. A.; Wilson, R. J.; Tseng, W.; Ip, W.

2009-12-01

The primary source of neutral O2 for Saturn’s magnetosphere is due to solar UV photons protons that produce O2 from H2O ice decomposition over the main rings as well as the tenuous F and G rings resulting in a tenuous O2 atmosphere (Johnson et. al. 2006). The O2 atmosphere is very thin to the point of being nearly collisionless. Our model of the atmosphere predict that as it interacts with the ring particles, the O2 is adsorbed and desorbed from the rings causing changes in the trajectories, which in turn, allows for a distribution of O2 from the rings throughout the magnetosphere (Tokar et. al. 2005; Tseng et. al. 2009). Predominately through photo-ionization and ion-exchange these O2 neutrals from the ice grains become a source for O2+ ions in the inner magnetosphere. Once the O2 becomes ionized to become O2+ the ions then follow the field lines. The ions interact with the ice particles in the rings to stick to the ring particles effectively reducing the ion density. As a result the ion density is greater over the Cassini Division and the area between the F and G ring where the optical depth due to the ice grain is less. Accordingly, the neutral O2 densities would tend to be high over the higher optical depth of the B and A main rings where the source rates are higher. Models of the neutral densities have shown high densities over the main rings, with a tail through the magnetosphere. Analysis of the CAPS (Cassini Plasma Spectrometer) data from the Saturn Orbit Insertion (SOI) in 2004 shows a peak in density over the Cassini Division and a higher peak in O2+ ion density between the F and G rings. References: Johnson, R.E., J.G. Luhmann, R.L. Tokar, M. Bouhram, J.J. Berthelier, E.C. Siler, J.F. Cooper, T.W. Hill, H.T. Smith, M. Michael, M. Liu, F.J. Crary, D.T. Young, "Production, Ionization and Redistribution of O2 Saturn's Ring Atmosphere" Icarus 180, 393-402 (2006).(pdf) Tokar, R.L., and 12 colleagues, 2005. Cassini Observations of the Thermal Plasma in the

Development of a new seal for use on large openings of pressurized spacecraft

NASA Technical Reports Server (NTRS)

Weddendorf, B.

1994-01-01

The goal of this project was to design, build, and test an example of the seal invented by the author for use on Space Station Freedom and patented in 1991. The seal features a metallic spring core and replaceable elastomeric sealing elements. The metallic spring is designed to retain the sealing force of the elastomeric element against both sides of face seal gland for any specified amount of waviness or separation of the glands. A seal able to tolerate at least 1.3 mm (0.05 in) of flange distortion or separation and a test fixture of this seal which allowed direct comparison testing of O-rings were built. These designs were tested to compare leakage at different amounts of flange deflection. Results of the testing show the development seal exceeded its requirement to seal 1.3 mm of flange separation by 1 mm. This compared with the O-ring leakage, increasing dramatically at 0.5 mm of separation. The development seal also leaked at a lower rate than the O-ring seals in all tests.

Selective Ring Opening of 1-Methylnaphthalene Over NiW-Supported Catalyst Using Dealuminated Beta Zeolite.

PubMed

Kim, Eun-Sang; Lee, You-Jin; Kim, Jeong-Rang; Kim, Joo-Wan; Kim, Tae-Wan; Chae, Ho-Jeong; Kim, Chul-Ung; Lee, Chang-Ha; Jeong, Soon-Yong

2016-02-01

Nanoporous Beta zeolite was dealuminated by weak acid treatment for reducing the acidity. Bi-functional catalysts were prepared using commercial Beta zeolites and the dealuminated zeolites for acidic function, NiW for metallic function. 1-Methylnaphthalene was selected as a model compound for multi-ring aromatics in heavy oil, and its selective ring opening reaction has been investigated using the prepared bi-functional catalysts with different acidity in fixed bed reaction system. The dealuminated Beta zeolites, which crystal structure and nanoporosity were maintained, showed the higher SiO2/Al2O3 ratio and smaller acidity than their original zeolite. NiW-supported catalyst using the dealuminated Beta zeolite with SiO2/Al203 mole ratio of 55 showed the highest performance for the selective ring opening. The acidity of catalyst seemed to play an important role as active sites for the selective ring opening of 1-methylnaphthalene but there should be some optimum catalyst acidity for the reaction. The acidity of Beta zeolite could be controlled by the acid treatment and the catalyst with the optimum acidity for the selective ring opening could be prepared.

Evolution of the Proximal Sealing Rings of the Anaconda Stent-Graft After Endovascular Aneurysm Repair.

PubMed

Koenrades, Maaike A; Klein, Almar; Leferink, Anne M; Slump, Cornelis H; Geelkerken, Robert H

2018-04-01

To provide insight into the evolution of the saddle-shaped proximal sealing rings of the Anaconda stent-graft after endovascular aneurysm repair (EVAR). Eighteen abdominal aortic aneurysm patients were consecutively enrolled in a single-center, prospective, observational cohort study (LSPEAS; Trialregister.nl identifier NTR4276). The patients were treated electively using an Anaconda stent-graft with a mean 31% oversizing (range 17-47). According to protocol, participants were to be followed for 2 years, during which 5 noncontrast electrocardiogram-gated computed tomography scans would be conducted. Three patients were eliminated within 30 days (1 withdrew, 1 died, and a third was converted before stent-graft deployment), leaving 15 patients (mean age 72.8±3.7 years; 14 men) for this analysis. Evolution in size and shape (symmetry) of both proximal infrarenal sealing rings were assessed from discharge to 24 months using dedicated postprocessing algorithms. At 24 months, the mean diameters of the first and second ring stents had increased significantly (first ring: 2.2±1.0 mm, p<0.001; second ring: 2.7±1.1 mm, p<0.001). At 6 months, the first and second rings had expanded to a mean 96.6%±2.1% and 94.8%±2.7%, respectively, of their nominal diameter, after which the rings expanded slowly; ring diameters stabilized to near nominal size (first ring, 98.3%±1.1%; second ring, 97.2%±1.4%) at 24 months irrespective of initial oversizing. No type I or III endoleaks or aneurysm-, device-, or procedure-related adverse events were noted in follow-up. The difference in the diametric distances between the peaks and valleys of the saddle-shaped rings was marked at discharge but became smaller after 24 months for both rings (first ring: median 2.0 vs 1.2 mm, p=0.191; second ring: median 2.8 vs 0.8 mm; p=0.013). Irrespective of initial oversizing, the Anaconda proximal sealing rings radially expanded to near nominal size within 6 months after EVAR. Initial oval-shaped rings

Development and Evaluation of Phosphonitrilic Fluoroelastomer O-Rings.

DTIC Science & Technology

1975-04-01

and having the following formula: c 0CH2(CF2$CF2H n 1 The polymer contained svfflclent cure sites to attain good curability with mnvent~onai...cable with phosphonitrilic fluoroelastomer compounds. A good quality coating of approximately 0,031" thickness was obtained by passing the cable through...extreme low temperature flexibility, outstanding fluid resistance, good heat resis- tance and good dynnmic properties. O-ring seals are one such

Local contamination, and not feeding preferences, explains elevated PCB concentrations in Labrador ringed seals (Pusa hispida).

PubMed

Brown, Tanya M; Iverson, Sara J; Fisk, Aaron T; Macdonald, Robie W; Helbing, Caren C; Reimer, Ken J

2015-05-15

Polychlorinated biphenyls (PCBs) in high trophic level species typically reflect the contributions of myriad sources, such that source apportionment is rarely possible. The release of PCBs by a military radar station into Saglek Bay, Labrador contaminated the local marine food web. For instance, while heavier (higher chlorinated) PCB profiles in some ringed seals (Pusa hispida) were previously attributed to this local source, differences in feeding preferences among seals could not be ruled out as a contributing factor. Herein, similar fatty acid profiles between those seals with 'local' PCB profiles and those with 'long-range' or background profiles indicate little support for the possibility that differential feeding ecologies underlay the divergent PCB profiles. Ringed seals appeared to feed predominantly on zooplankton (Mysis oculata and Themisto libellula), followed by the dusky snailfish (Liparis gibbus), arctic cod (Boreogadus saida), and shorthorn sculpin (Myoxocephalus scorpius). Principal components analysis (PCA) and PCB homolog profiles illustrated the extent of contamination of the Saglek food web, which had very different (and much heavier) PCB profiles than those food web members contaminated by 'long-range' sources. Locally contaminated prey had PCB levels that were higher (2- to 544-fold) than prey contaminated by 'long-range' sources and exceeded wildlife consumption guidelines for PCBs. The application of multivariate analyses to two distinct datasets, including PCB congeners (n=50) and fatty acids (n=65), afforded the opportunity to clearly distinguish the contribution of locally-released PCBs to a ringed seal food web from those delivered via long-ranged transport. Results from the present study strongly suggest that habitat use rather than differences in prey selection is the primary mechanism explaining the divergent PCB patterns in Labrador ringed seals. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of a Conductive Elastomer Seal for Spacecraft

NASA Technical Reports Server (NTRS)

Daniels, C. C.; Mather, J. L.; Oravec, H. A.; Dunlap, P. H., Jr.

2016-01-01

An electrically conductive elastomer was evaluated as a material candidate for a spacecraft seal. The elastomer used electrically conductive constituents as a means to reduce the resistance between mating interfaces of a sealed joint to meet spacecraft electrical bonding requirements. The compound's outgassing levels were compared against published NASA requirements. The compound was formed into a hollow O-ring seal and its compression set was measured. The O-ring seal was placed into an interface and the electrical resistance and leak rate were quantified. The amount of force required to fully compress the test article in the sealing interface and the force needed to separate the joint were also measured. The outgassing and resistance measurements were below the maximum allowable levels. The room temperature compression set and leak rates were fairly high when compared against other typical spacecraft seal materials, but were not excessive. The compression and adhesion forces were desirably low. Overall, the performance of the elastomer compound was sufficient to be considered for future spacecraft seal applications.

Nitrile O-ring Cracking: A Case of Vacuum Flange O-ring Failures

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

Dees, Craig

2016-07-01

A review of recent nitrile O-ring failures in ISO-KF vacuum flange connections in glovebox applications is presented. An investigation of a single “isolated” o-ring failure leads to the discovery of cracked nitrile o-rings in a glovebox atmospheric control unit. The initial cause of the o-ring failure is attributed to ozone degradation. However, additional investigation reveals nitrile o-ring cracking on multiple gloveboxes and general purpose piping, roughly 85% of the nitrile o-rings removed for inspection show evidence of visible cracking after being in service for 18 months or less. The results of material testing and ambient air testing is presented, elevatedmore » ozone levels are not found. The contributing factors of o-ring failure, including nitrile air sensitivity, inadequate storage practices, and poor installation techniques, are discussed. A discussion of nitrile o-ring material properties, the benefits and limitations, and alternate materials are discussed. Considerations for o-ring material selection, purchasing, storage, and installation are presented in the context of lessons learned from the nitrile o-ring cracking investigation. This paper can be presented in 20 minutes and does not require special accommodations or special audio visual devices.« less

Hg Stable Isotope Time Trend in Ringed Seals Registers Decreasing Sea Ice Cover in the Alaskan Arctic.

PubMed

Masbou, Jérémy; Point, David; Sonke, Jeroen E; Frappart, Frédéric; Perrot, Vincent; Amouroux, David; Richard, Pierre; Becker, Paul R

2015-08-04

Decadal time trends of mercury (Hg) concentrations in Arctic biota suggest that anthropogenic Hg is not the single dominant factor modulating Hg exposure to Arctic wildlife. Here, we present Hg speciation (monomethyl-Hg) and stable isotopic composition (C, N, Hg) of 53 Alaskan ringed seal liver samples covering a period of 14 years (1988-2002). In vivo metabolic effects and foraging ecology explain most of the observed 1.6 ‰ variation in liver δ(202)Hg, but not Δ(199)Hg. Ringed seal habitat use and migration were the most likely factors explaining Δ(199)Hg variations. Average Δ(199)Hg in ringed seal liver samples from Barrow increased significantly from +0.38 ± 0.08‰ (±SE, n = 5) in 1988 to +0.59 ± 0.07‰ (±SE, n = 7) in 2002 (4.1 ± 1.2% per year, p < 0.001). Δ(199)Hg in marine biological tissues is thought to reflect marine Hg photochemistry before biouptake and bioaccumulation. A spatiotemporal analysis of sea ice cover that accounts for the habitat of ringed seals suggests that the observed increase in Δ(199)Hg may have been caused by the progressive summer sea ice disappearance between 1988 and 2002. While changes in seal liver Δ(199)Hg values suggests a mild sea ice control on marine MMHg breakdown, the effect is not large enough to induce measurable HgT changes in biota. This suggests that Hg trends in biota in the context of a warming Arctic are likely controlled by other processes.

Circumferential shaft seal

NASA Technical Reports Server (NTRS)

Ludwig, L. P. (Inventor)

1981-01-01

A circumferential shaft seal comprising two sealing rings held to a rotating shaft by means of a surrounding elastomeric band is disclosed. The rings are segmented and are of a rigid sealing material such as carbon or a polyimide and graphite fiber composite.

Sealed-off CO2 laser with In-Au alloy sealing

NASA Astrophysics Data System (ADS)

Iehisa, N.; Fukaya, K.; Karube, N.

1986-02-01

The In-Au alloy sealing was found to satisfy all the requirements imposed on the sealed-off CO2 lasers. The sealing between different materials such as quartz, SUS 303, Si, and ZnSe was shown to withstand the thermal shock test, and gave the He leak rate lower than 1×10-9 atm cc/s both before and after the tests. It was also proved that the transmittance characteristics of dielectric coated output couplers did not change after the sealing. The sealed-off CO2 lasers with La1-xSrxCoO3 perovskite oxide cathodes sealed with this technique produced the operational life of 3000 h at the laser power level of 50 W/m.

Design and analysis of seals for extended service life

NASA Technical Reports Server (NTRS)

Bower, Mark V.

1992-01-01

Space Station Freedom is being developed for a service life of up to thirty years. As a consequence, the design requirements for the seals to be used are unprecedented. Full scale testing to assure the selected seals can satisfy the design requirements are not feasible. As an alternative, a sub-scale test program has been developed by MSFC to calibrate the analysis tools to be used to certify the proposed design. This research has been conducted in support of the MSFC Integrated Seal Test Program. The ultimate objective of this research is to correlate analysis and test results to qualify the analytical tools, which in turn, are to be used to qualify the flight hardware. This research is totally focused on O-rings that are compressed by perpendicular clamping forces. In this type of seal the O-ring is clamped between the sealing surfaces by loads perpendicular to the circular cross section.

Circumferential shaft seal

NASA Technical Reports Server (NTRS)

Ludwig, L. P. (Inventor)

1980-01-01

A circumferential shaft seal is described which comprises two sealing rings held to a rotating shaft by means of a surrounding elastomeric band. The rings are segmented and are of a rigid sealing material such as carbon or a polyimide and graphite fiber composite.

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.

Improved circumferential shaft seal

NASA Technical Reports Server (NTRS)

Ludwig, L. P.; Strom, T. N.

1974-01-01

Comparative tests of modified and unmodified carbon ring seals showed that addition of helical grooves to conventional segmented carbon ring seals reduced leakage significantly. Modified seal was insensitive to shaft runout and to flooding by lubricant.

Bioaccumulation and biotransformation of brominated and chlorinated contaminants and their metabolites in ringed seals (Pusa hispida) and polar bears (Ursus maritimus) from East Greenland.

PubMed

Letcher, Robert J; Gebbink, Wouter A; Sonne, Christian; Born, Erik W; McKinney, Melissa A; Dietz, Rune

2009-11-01

We report on the comparative bioaccumulation, biotransformation and/or biomagnification from East Greenland ringed seal (Pusa hispida) blubber to polar bear (Ursus maritimus) tissues (adipose, liver and brain) of various classes and congeners of persistent chlorinated and brominated contaminants and metabolic by-products: polychlorinated biphenyls (PCBs), chlordanes (CHLs), hydroxyl (OH-) and methylsulfonyl (MeSO(2)-) PCBs, polybrominated biphenyls (PBBs), OH-PBBs, polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) flame retardants and OH- and methoxyl (MeO-) PBDEs, 2,2-dichloro-bis(4-chlorophenyl)ethene (p,p'-DDE), 3-MeSO(2)-p,p'-DDE, pentachlorophenol (PCP) and 4-OH-heptachlorostyrene (4-OH-HpCS). We detected all of the investigated contaminants in ringed seal blubber with high frequency, the main diet of East Greenland bears, with the exception of OH-PCBs and 4-OH-HpCS, which indicated that these phenolic contaminants were likely of metabolic origin and formed in the bears from accumulated PCBs and octachlorostyrene (OCS), respectively, rather than being bioaccumulated from a seal blubber diet. For all of the detectable sum of classes or individual organohalogens, in general, the ringed seal to polar bear mean BMFs for SigmaPCBs, p,p'-DDE, SigmaCHLs, SigmaMeSO(2)-PCBs, 3-MeSO(2)-p,p'-DDE, PCP, SigmaPBDEs, total-(alpha)-HBCD, SigmaOH-PBDEs, SigmaMeO-PBDEs and SigmaOH-PBBs indicated that these organohalogens bioaccumulate, and in some cases there was tissue-specific biomagnification, e.g., BMFs for bear adipose and liver ranged from 2 to 570. The blood-brain barrier appeared to be effective in minimizing brain accumulation as BMFs were seal blubber rather than being metabolic formed from PBDEs in the bears. In vitro PBDE depletion assays using polar bear hepatic microsomes

Flight set 360H005 (STS-28) seals, volume 4

NASA Technical Reports Server (NTRS)

Curry, Jeffrey T.

1990-01-01

The performance is assessed of the 360H005, Fifth flight, Redesigned Solid Rocket Motors (RSMR) in respect to joint sealing issues as seen from post flight inspection of the seals and sealing surfaces. The factory joint disassembly inspections have resumed for 360H005. The new factory joint grease application is in effect and now can be assessed during the disassembly process. The RSRM is illustrated consisting of capture feature field joints as is the J-joint insulation configuration. The nozzle-to-case joint design is also illustrated, which includes 100, 7/8 inch radial bolts in conjunction with a wiper O-ring and modified insulation design. The ignition system seals and a cross section of the igniter are illustrated. The configuration of all the internal nozzle joints are also shown. The postflight inspection of both motors showed the seal components to be in excellent condition except for the indentation found on the inner primary seal of the right hand inner igniter gasket, aft face. Detailed inspection results, and inspections performed by the O-ring Inspection Team are presented.

Rim seal for turbine wheel

DOEpatents

Glezer, Boris; Boyd, Gary L.; Norton, Paul F.

1996-01-01

A turbine wheel assembly includes a disk having a plurality of blades therearound. A ceramic ring is mounted to the housing of the turbine wheel assembly. A labyrinth rim seal mounted on the disk cooperates with the ceramic ring to seal the hot gases acting on the blades from the disk. The ceramic ring permits a tighter clearance between the labyrinth rim seal and the ceramic ring.

Ultra high vacuum seal arrangement

DOEpatents

Flaherty, Robert

1981-01-01

Arrangement for demountably sealing two concentric metallic tubes in an ultra high vacuum system which facilitates remote actuation. A tubular seal includes integral spaced lips which circumferentially engage the metallic tubes. The lips plastically deform the metallic tubes by mechanical forces resulting from a martensite to austenite transformation of the tubular seal upon application of a predetermined temperature. The sealing force is released upon application of another temperature which causes a transformation from the stronger austenite to the weaker martensite. Use of a dual acting sealing ring and driving ring circumferentially contacting the sealing ring is particularly applicable to sealing larger diameter concentric metallic members.

Orbital transfer rocket engine technology program: Soft wear ring seal technology

NASA Technical Reports Server (NTRS)

Lariviere, Brian W.

1992-01-01

Liquid oxygen (LOX) compatibility tests, including autogenous ignition, promoted ignition, LOX impact tests, and friction and wear tests on different PV products were conducted for several polymer materials as verification for the implementation of soft wear ring seals in advanced rocket engine turbopumps. Thermoplastics, polyimide based materials, and polyimide-imide base materials were compared for oxygen compatibility, specific wear coefficient, wear debris production, and heat dissipation mechanisms. A thermal model was generated that simulated the frictional heating input and calculated the surface temperature and temperature distribution within the seal. The predictions were compared against measured values. Heat loads in the model were varied to better match the test data and determine the difference between the measured and the calculated coefficients of friction.

Tamper indicating seal

DOEpatents

Romero, Juan A [Albuquerque, NM; Walker, Charles A [Albuquerque, NM; Blair, Dianna S [Albuquerque, NM; Bodmer, Connie C [Albuquerque, NM

2012-05-29

Seals have a flexible wire that can be looped through a hasp-like device. The seals include a body having a recess, a plug insertable into the recess and a snap ring for fastening the plug to the body. The plug and/or body can have access holes for inserting the wire into the recess. "Teeth" on the outer diameter and through-holes through the thickness of the snap ring allow for passing the ends of the flexible wire from the recess through the snap ring. The ends of the wire can be folded back over the snap ring and into engagement with the teeth. Assembly of the seal causes the ends of the wire to be securely fastened between the teeth of the snap ring and the sidewall of the recess. Seals can include a plug and/or body made of a frangible material such as glass, ceramic, glass-ceramic or brittle polymer.

Combined Genetic and Telemetry Data Reveal High Rates of Gene Flow, Migration, and Long-Distance Dispersal Potential in Arctic Ringed Seals (Pusa hispida)

PubMed Central

Martinez-Bakker, Micaela E.; Sell, Stephanie K.; Swanson, Bradley J.; Kelly, Brendan P.; Tallmon, David A.

2013-01-01

Ringed seals (Pusa hispida) are broadly distributed in seasonally ice covered seas, and their survival and reproductive success is intricately linked to sea ice and snow. Climatic warming is diminishing Arctic snow and sea ice and threatens to endanger ringed seals in the foreseeable future. We investigated the population structure and connectedness within and among three subspecies: Arctic (P. hispida hispida), Baltic (P. hispida botnica), and Lake Saimaa (P. hispida saimensis) ringed seals to assess their capacity to respond to rapid environmental changes. We consider (a) the geographical scale of migration, (b) use of sea ice, and (c) the amount of gene flow between subspecies. Seasonal movements and use of sea ice were determined for 27 seals tracked via satellite telemetry. Additionally, population genetic analyses were conducted using 354 seals representative of each subspecies and 11 breeding sites. Genetic analyses included sequences from two mitochondrial regions and genotypes of 9 microsatellite loci. We found that ringed seals disperse on a pan-Arctic scale and both males and females may migrate long distances during the summer months when sea ice extent is minimal. Gene flow among Arctic breeding sites and between the Arctic and the Baltic Sea subspecies was high; these two subspecies are interconnected as are breeding sites within the Arctic subspecies. PMID:24130843

Macroscopic anatomy of the great vessels and structures associated with the heart of the ringed seal (Pusa hispida).

PubMed

Smodlaka, H; Henry, R W; Reed, R B

2009-06-01

The ringed seal [Pusa (Phoca) hispida], as well as other seals, exhibits unique anatomical properties when compared to its terrestrial counterparts. In the ringed seal, the most conspicuous marine adaptation is the aortic bulb. This large dilatation of the ascending aorta is comparable to that found in other seal species and marine mammals. The branches of the ascending aorta (brachiocephalic trunk, left common carotid artery and left subclavian artery) are similar to those of higher primates and man. The peculiarities of the venous system are: three pulmonary veins, a pericardial venous plexus, a caval sphincter, a hepatic sinus with paired caudal vena cavae and a large extradural venous plexus. Generally, three common pulmonary veins (right, left and caudal) empty into the left atrium. The pericardial venous plexus lies deep to the mediastinal pericardial pleura (pleura pericardica) on the auricular (ventral) surface of the heart. The caval sphincter surrounds the caudal vena cava as it passes through the diaphragm. Caudal to the diaphragm, the vena cava is dilated (the hepatic sinus), and near the cranial extremity of the kidneys, it becomes biphid. The azygos vein is formed from the union of the right and left azygos veins at the level of the 5th thoracic vertebra. Cardiovascular physiological studies show some of these anatomical variations, especially of the venous system and the ascending aorta, to be modifications for diving. This investigation documents the large blood vessels associated with the heart and related structures in the ringed seal.

Rotatable seal assembly

DOEpatents

Logan, Clinton M.; Garibaldi, Jack L.

1982-01-01

An assembly is provided for rotatably supporting a rotor on a stator so that vacuum chambers in the rotor and stator remain in communication while the chambers are sealed from ambient air, which enables the use of a ball bearing or the like to support most of the weight of the rotor. The apparatus includes a seal device mounted on the rotor to rotate therewith, but shiftable in position on the rotor while being sealed to the rotor as by an O-ring. The seal device has a flat face that is biased towards a flat face on the stator, and pressurized air is pumped between the faces to prevent contact between them while spacing them a small distance apart to avoid the inflow of large amounts of air between the faces and into the vacuum chambers.

Gross anatomy of the ringed seal (Pusa hispida) gastro-intestinal tract.

PubMed

Smodlaka, H; Henry, R W

2014-06-01

The gross anatomical structure of the ringed seal (Pusa hispida) gastrointestinal tract is poorly described and often veterinary anatomical terminology is not used. Although the basic abdominal visceral pattern corresponded to domestic carnivores, significant differences were noted. The stomach was an elongated sharply bent tube (u-shaped) with the pylorus and fundus juxtaposed. The elongated jejunum measured up to 15.6 times body length and had 37 jejunal arteries from the cranial mesenteric artery. The pancreas was asymmetrical with a small right lobe and a large left lobe. The unusually short greater omentum negated formation of deep and superficial leaves. The most remarkable difference was the separation of the liver parenchyma into three physically separate masses, held together by hepatic ducts, veins and arteries. The topography and position of the liver was dependent on the amount of blood in the hepatic sinus (distended hepatic veins and hepatic portion of vena cava). Thus, as the hepatic sinus filled, the lateral liver masses separate from the central mass by moving caudolaterally. This was facilitated by modified coronary and triangular ligaments which did not attach directly to the liver, but instead to the hepatic sinus. These anatomical adaptations are apparently advantageous to ringed seal's survival in a deep marine environment. © 2013 Blackwell Verlag GmbH.

Synthesis, structure, and characterization of a new sandwich-type arsenotungstocerate, [As 2W 18Ce 3O 71(H 2O) 3] 12-

NASA Astrophysics Data System (ADS)

Alizadeh, M. H.; Eshtiagh-Hosseini, H.; Khoshnavazi, R.

2004-01-01

The rational synthesis of the new sandwich-type arsenotungstocerate [As 2W 18Ce 3O 71(H 2O) 3] 12- is reported for the first time by reaction of the trivacant lacunary species A-α-[AsW 9O 34] 9- with appropriate Ce IV. The single crystal structure analysis was carried out on K 7(H 3O) 5[As 2W 18Ce 3O 71(H 2O) 3]·9H 2O; H 39As 2Ce 3K 7O 88W 18; ( 2) which crystallizes in triclinic system, space group P overline1 with a=11.615(5) Å, b=17.638(7) Å, c=19.448(8) Å, α=73.643(7)°, β=88.799(7)°, γ=88.078(7)° and Z=2. The anion consists on two lacunary A-α-[AsW 9O 34] 9- Keggin moieties linked via a (H 2OCeO) 3 belt leading to a sandwich-type structure. Each cerium atom adopts tri-capped trigonal-prismatic coordination achieved by two terminal oxygen of an edge shared paired of WO 6 octahedra to each A-α-AsW 9O 349- moiety and two oxygen from the belt and the cap by one μ 3-O (As, W 2) to each A-α-AsW 9O 349- moiety and one external water ligand. The Ce-O bond lengths average in CeO 6 group, Ce-O(As, W 2) and Ce-O(nW) are 2.300(9), 2.887(3) and 2.682(5) Å, respectively. The acid/base titration curve reveals that the anion has two different titrable protons.

Face seal assembly for rotating drum

DOEpatents

Morgan, J. Giles; Rennich, Mark J.; Whatley, Marvin E.

1982-01-01

A seal assembly comprises a tube rotatable about its longitudinal axis and having two longitudinally spaced flanges projecting radially outwardly from the outer surface thereof. Slidably positioned against one of the flanges is a seal ring, and disposed between this seal ring and the other flange are two rings that are forced apart by springs, one of the latter rings being attached to a flexible wall.

Finite Element Analysis of Elastomeric Seals for LIDS

NASA Technical Reports Server (NTRS)

Oswald, Jay J.; Daniels, Christopher C.

2007-01-01

Objective: Create a means of evaluating seals w/o prototypes. Motivation: Cost Prototype 54" seal approx.$100k per seal pair FEA license + high end workstation approx. $30k per year. Development time: 6 months lead time for a new seal design Many designs per day (solution time <1 minute) Understanding: Difficult to experimentally measure strains, contact pressure profile, stresses, displacements

Ringed Seal Search for Global Optimization via a Sensitive Search Model.

PubMed

Saadi, Younes; Yanto, Iwan Tri Riyadi; Herawan, Tutut; Balakrishnan, Vimala; Chiroma, Haruna; Risnumawan, Anhar

2016-01-01

The efficiency of a metaheuristic algorithm for global optimization is based on its ability to search and find the global optimum. However, a good search often requires to be balanced between exploration and exploitation of the search space. In this paper, a new metaheuristic algorithm called Ringed Seal Search (RSS) is introduced. It is inspired by the natural behavior of the seal pup. This algorithm mimics the seal pup movement behavior and its ability to search and choose the best lair to escape predators. The scenario starts once the seal mother gives birth to a new pup in a birthing lair that is constructed for this purpose. The seal pup strategy consists of searching and selecting the best lair by performing a random walk to find a new lair. Affected by the sensitive nature of seals against external noise emitted by predators, the random walk of the seal pup takes two different search states, normal state and urgent state. In the normal state, the pup performs an intensive search between closely adjacent lairs; this movement is modeled via a Brownian walk. In an urgent state, the pup leaves the proximity area and performs an extensive search to find a new lair from sparse targets; this movement is modeled via a Levy walk. The switch between these two states is realized by the random noise emitted by predators. The algorithm keeps switching between normal and urgent states until the global optimum is reached. Tests and validations were performed using fifteen benchmark test functions to compare the performance of RSS with other baseline algorithms. The results show that RSS is more efficient than Genetic Algorithm, Particles Swarm Optimization and Cuckoo Search in terms of convergence rate to the global optimum. The RSS shows an improvement in terms of balance between exploration (extensive) and exploitation (intensive) of the search space. The RSS can efficiently mimic seal pups behavior to find best lair and provide a new algorithm to be used in global

Ringed Seal Search for Global Optimization via a Sensitive Search Model

PubMed Central

Saadi, Younes; Yanto, Iwan Tri Riyadi; Herawan, Tutut; Balakrishnan, Vimala; Chiroma, Haruna; Risnumawan, Anhar

2016-01-01

The efficiency of a metaheuristic algorithm for global optimization is based on its ability to search and find the global optimum. However, a good search often requires to be balanced between exploration and exploitation of the search space. In this paper, a new metaheuristic algorithm called Ringed Seal Search (RSS) is introduced. It is inspired by the natural behavior of the seal pup. This algorithm mimics the seal pup movement behavior and its ability to search and choose the best lair to escape predators. The scenario starts once the seal mother gives birth to a new pup in a birthing lair that is constructed for this purpose. The seal pup strategy consists of searching and selecting the best lair by performing a random walk to find a new lair. Affected by the sensitive nature of seals against external noise emitted by predators, the random walk of the seal pup takes two different search states, normal state and urgent state. In the normal state, the pup performs an intensive search between closely adjacent lairs; this movement is modeled via a Brownian walk. In an urgent state, the pup leaves the proximity area and performs an extensive search to find a new lair from sparse targets; this movement is modeled via a Levy walk. The switch between these two states is realized by the random noise emitted by predators. The algorithm keeps switching between normal and urgent states until the global optimum is reached. Tests and validations were performed using fifteen benchmark test functions to compare the performance of RSS with other baseline algorithms. The results show that RSS is more efficient than Genetic Algorithm, Particles Swarm Optimization and Cuckoo Search in terms of convergence rate to the global optimum. The RSS shows an improvement in terms of balance between exploration (extensive) and exploitation (intensive) of the search space. The RSS can efficiently mimic seal pups behavior to find best lair and provide a new algorithm to be used in global

76 FR 9733 - Endangered and Threatened Species; Proposed Threatened Status for Subspecies of the Ringed Seal

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-22

..., we, NMFS, published a proposed rule to list the Arctic (Phoca hispida hispida), Okhotsk (Phoca... the Arctic, Okhotsk, Baltic, and Ladoga subspecies of the ringed seal as threatened under the ESA...

76 FR 14882 - Endangered and Threatened Species; Proposed Threatened Status for Subspecies of the Ringed Seal

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-18

... rule to list the Arctic (Phoca hispida hispida), Okhotsk (Phoca hispida ochotensis), Baltic (Phoca... rule to list the Arctic, Okhotsk, Baltic, and Ladoga subspecies of the ringed seal as threatened under...

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.

Seal assembly with anti-rotation pin for high pressure supercritical fluids

DOEpatents

Wright, Steven A.; Fuller, Robert L.

2014-08-05

A seal assembly for sealing a machine with a first chamber and a second chamber is provided. A rotating shaft extends through the first and second chambers, and rotates therein. The seal assembly has a seal housing, a seal ring and a seal pin. The seal housing is positionable in the machine housing. The seal housing has a seal pocket extending into a fluid side thereof, and a housing receptacle extending into an inner diameter thereof at the seal pocket. The seal ring is positionable in the seal pocket of the seal housing for forming a seal therewith. The seal ring has a ring receptacle extending into an outer diameter thereof. The ring receptacle is positionable adjacent to the housing receptacle for defining a pin hole therebetween. The seal pin is loosely positionable in the pin hole whereby movement about the seal ring is accommodated while preventing rotation thereof.

A comparison of ringed and bearded seal diet, condition and productivity between historical (1975-1984) and recent (2003-2012) periods in the Alaskan Bering and Chukchi seas

NASA Astrophysics Data System (ADS)

Crawford, Justin A.; Quakenbush, Lori T.; Citta, John J.

2015-08-01

Reductions in summer sea ice in the Chukchi and Beaufort seas are expected to affect what has been an ice-adapted marine food web in the Pacific Arctic. To determine whether recent decreases in sea ice have affected ice-associated marine predators (i.e., ringed, Pusa hispida, and bearded seals, Erignathus barbatus) in the Bering and Chukchi seas we compared diet, body condition, growth, productivity, and the proportion of pups harvested (an index of weaning success) for seals of each species harvested by 11 Alaskan villages during two periods; a historical (1975-1984) and a recent period (2003-2012). We also examined how changes in indices of seal health may be correlated with the reduction of sea ice characteristic of the recent period. For ringed seals ⩾1 year of age, the % frequency of occurrence (%FO) of Arctic cod (Boreogadus saida), walleye pollock (Gadus chalcogramma), rainbow smelt (Osmerus mordax), and Pacific herring (Clupea pallasi) increased from the historic to the recent period, while the %FO of invertebrates decreased for both pups and seals ⩾1 year of age. For bearded seals ⩾1 year of age, the %FO of Arctic cod, pricklebacks, and flatfish increased during the recent period, while the %FO of saffron cod (Eleginus gracilis) decreased for pups. Although invertebrates did not change overall for either age class, decreases occurred in 10 of 24 specific prey categories, for bearded seals ⩾1 year of age; only echiurids increased. The %FO of gastropods and bivalves increased for pups while isopods and one species of shrimp and crab decreased in occurrence. During the recent period ringed seals grew faster, had thicker blubber, had no change in pregnancy rate, matured 2 years earlier, and a larger proportion of pups was harvested than during the historical period. Correlations with spring ice concentration showed that the growth and blubber thickness of seals ⩾1 year of age, blubber thickness of pups, and the proportion of pups in the harvest all

Rotary shaft sealing assembly

DOEpatents

Dietle, Lannie L; Schroeder, John E; Kalsi, Manmohan S; Alvarez, Patricio D

2013-08-13

A rotary shaft sealing assembly in which a first fluid is partitioned from a second fluid in a housing assembly having a rotary shaft located at least partially within. In one embodiment a lip seal is lubricated and flushed with a pressure-generating seal ring preferably having an angled diverting feature. The pressure-generating seal ring and a hydrodynamic seal may be used to define a lubricant-filled region with each of the seals having hydrodynamic inlets facing the lubricant-filled region. Another aspect of the sealing assembly is having a seal to contain pressurized lubricant while withstanding high rotary speeds. Another rotary shaft sealing assembly embodiment includes a lubricant supply providing a lubricant at an elevated pressure to a region between a lip seal and a hydrodynamic seal with a flow control regulating the flow of lubricant past the lip seal. The hydrodynamic seal may include an energizer element having a modulus of elasticity greater than the modulus of elasticity of a sealing lip of the hydrodynamic seal.

Rotary shaft sealing assembly

DOEpatents

Dietle, Lannie L.; Schroeder, John E.; Kalsi, Manmohan S.; Alvarez, Patricio D.

2010-09-21

A rotary shaft sealing assembly in which a first fluid is partitioned from a second fluid in a housing assembly having a rotary shaft located at least partially within. In one embodiment a lip seal is lubricated and flushed with a pressure-generating seal ring preferably having an angled diverting feature. The pressure-generating seal ring and a hydrodynamic seal may be used to define a lubricant-filled region with each of the seals having hydrodynamic inlets facing the lubricant-filled region. Another aspect of the sealing assembly is having a seal to contain pressurized lubricant while withstanding high rotary speeds. Another rotary shaft sealing assembly embodiment includes a lubricant supply providing a lubricant at an elevated pressure to a region between a lip seal and a hydrodynamic seal with a flow control regulating the flow of lubricant past the lip seal. The hydrodynamic seal may include an energizer element having a modulus of elasticity greater than the modulus of elasticity of a sealing lip of the hydrodynamic seal.

Investigation of premature strip seal joint failures and recommendations for assuring proper strip seal joint installation: Bridge 5/104W.

DOT National Transportation Integrated Search

2015-08-01

This document summarizes an investigation that was performed to identify the cause(s) of premature failures of : strip seal expansion joints that were installed on WSDOT Bridge No. 5/104W. The document also includes recommendations : for assuring pro...

Pressure Seal For Frequently Opened Hatch

NASA Technical Reports Server (NTRS)

Kennedy, Steven E.; Kramer, Joel M.

1994-01-01

Pressure-assisted seal for frequently opened hatch includes two sealing rings retained positively so not pulled out during opening. Seal makes contact with hatch well before hatch starts to squeeze rings extending distance over which seal becomes engaged. Improvements include more-secure mounting, redundancy, and better initial sealing action. Also minimizes loss of gas during closure by deflecting inward and closing gap. This action helps differential pressure to force hatch closed.

Tritium, deuterium, and helium permeation through EPDM O-rings

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

Swansiger, W.A.

1992-03-01

This paper discusses tritium permeabilities determined at room temperature, 1.0 MPa (150 psia) tritium for three 23.4 cm diameter EPDM (ethylene-propylene-diene monomer) O-rings using a full-scale mock-up of the Al-SX shipping container seal geometry. The AL-SX container is being developed by Sandia National Laboratories for shipping tritium reservoirs. To determine the tritium permeation rate as a function of temperature, a 50.8 mm diameter EPDM O-ring was tested from room temperature to 150{degrees}C at a pressure of 1.0 MPa. Additional permeation measurements were made under the following test conditions: deuterium and helium-4 at room temperature and a pressure of 1.0 MPamore » using the full-scale AL-SX fixture, tritium from 0.1 MPa to 1.0 MPa at 142{degrees}C using the 50.8 mm fixture, and deuterium form room temperature to 150{degrees}C at a pressure of 1.0 MPa using the three full-scale O-rings showed the average room temperature, 1.0 MPa steady state tritium permeation rate to be about 1 {times} 10{sup {minus}2} Pa-liter/sec (7.6 {times} 10{sup {minus}5} torr-liter/sec or 1 {times} 10{sup {minus}4} std cc/sec), well within the allowable limit of 7.1 {times} 10{sup {minus}2} Pa-liter/sec for tritium release form the AL-SX container.« less

Containment penetration elastomer seal leak rate tests

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

Bridges, T.L.

1987-07-01

Tests were performed on three elastomer seal designs commonly used for nuclear plant containment mechanical penetrations. The objective of this research project is to obtain an understanding of the integrity and leakage behavior of these seal designs under severe accident temperature and pressure conditions. The three designs tested and the seal materials used in the tests were: (1) double tongue-and-groove design with silicone rubber seals, (2) double-O-ring design with neoprene and ethylene-propylene (EPDM) seals, and (3) double gumdrop design with neoprene and EPDM seals. The effects of thermal aging and angular rotations of flange mating surfaces were determined. The testmore » results provide information required to characterize the leakage behavior of penetrations under severe accident conditions. 3 refs., 10 figs., 12 tabs.« less

Multiple internal seal right micro-electro-mechanical system vacuum package

NASA Technical Reports Server (NTRS)

Shcheglov, Kirill V. (Inventor); Wiberg, Dean V. (Inventor); Hayworth, Ken J. (Inventor); Yee, Karl Y. (Inventor); Bae, Youngsam (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)

2007-01-01

A Multiple Internal Seal Ring (MISR) Micro-Electro-Mechanical System (MEMS) vacuum package that hermetically seals MEMS devices using MISR. The method bonds a capping plate having metal seal rings to a base plate having metal seal rings by wafer bonding the capping plate wafer to the base plate wafer. Bulk electrodes may be used to provide conductive paths between the seal rings on the base plate and the capping plate. All seals are made using only metal-to-metal seal rings deposited on the polished surfaces of the base plate and capping plate wafers. However, multiple electrical feed-through metal traces are provided by fabricating via holes through the capping plate for electrical connection from the outside of the package through the via-holes to the inside of the package. Each metal seal ring serves the dual purposes of hermetic sealing and providing the electrical feed-through metal trace.

Fractionation of Oxygen Isotopes by Thermal Ionization Mass Spectrometry Inferred from Simultaneous Measurement of (17)O/(16)O and (18)O/(16)O Ratios and Implications for the (182)Hf-(182)W Systematics.

PubMed

Trinquier, Anne

2016-06-07

Accurate (182)Hf-(182)W chronology of early planetary differentiation relies on highly precise and accurate tungsten isotope measurements. WO3(-) analysis by negative thermal ionization mass spectrometry requires W(17)O(16)O2(-), W(17)O2(16)O(-), W(18)O(16)O2(-), W(17)O3(-), W(17)O(18)O(16)O(-), and W(18)O2(16)O(-) isotopologue interference corrections on W(16)O3(-) species ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ; Touboul et al. Nature 2015 , 520 , 530 ; Touboul et al. Int. J. Mass Spectrom. 2012 , 309 , 109 ). In addition, low ion beam intensity counting statistics combined with Faraday cup detection noise limit the precision on the determination of (18)O/(16)O and (17)O/(16)O relative abundances. Mass dependent variability of (18)O/(16)O over the course of an analysis and between different analyses calls for oxide interference correction on a per integration basis, based on the in-run monitoring of the (18)O/(16)O ratio ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). Yet, the (17)O/(16)O variation is normally not being monitored and, instead, inferred from the measured (18)O/(16)O variation, assuming a δ(17)O-δ(18)O Terrestrial Fractionation Line ( Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). The purpose of the present study is to verify the validity of this assumption. Using high resistivity amplifiers, (238)U(17)O2 and (238)U(18)O2 ion beams down to 1.6 fA have been monitored simultaneously with (235,238)U(16)O2 species in a uranium certified reference material. This leads to a characterization of O isotope fractionation by thermal ionization mass spectrometry in variable loading and running conditions (additive-to-sample ratio, PO2 pressure, presence of ionized metal and oxide species). Proper determination of O

Observations of far-infrared fine structure lines: o III88.35 micrometer and oI 63.2 micrometer

NASA Technical Reports Server (NTRS)

Storey, J. W. V.; Watson, D. M.; Townes, C. H.

1979-01-01

Observations of the O III 88.35 micrometer line and the O I63.2 micrometer were made with a far infrared spectrometer. The sources M17, NGC 7538, and W51 were mapped in the O III line with 1 arc minute resolution and the emission is found to be quite widespread. In all cases the peak of the emission coincides with the maximum radio continuum. The far infrared continuum was mapped simultaneously and in M17, NGC 7538, and W51 the continuum peak is found to be distinct from the center of ionization. The O III line was also detected in W3, W49, and in a number of positions in the Orion nebula. Upper limits were obtained on NGS 7027, NGC 6572, DR21, G29.9-0.0 and M82. The 63.2 micrometer O I line was detected in M17, M42, and marginally in DR21. A partial map of M42 in this line shows that most of the emission observed arises from the Trapezium and from the bright optical bar to the southeast.

Electrical Characteristics of the Contour-Vibration-Mode Piezoelectric Transformer with Ring/Dot Electrode Area Ratio

NASA Astrophysics Data System (ADS)

Yoo, Juhyun; Yoon, Kwanghee; Lee, Yongwoo; Suh, Sungjae; Kim, Jongsun; Yoo, Chungsik

2000-05-01

Contour-vibration-mode Pb(Sb1/2Nb1/2)O3-Pb(Zr, Ti)O3 [PSN-PZT] piezoelectric transformers with different ring/dot electrode area ratios were fabricated to the size of 27.5× 27.5× 2.5 mm3 by cold isostatic pressing. The electrical properties and characteristic temperature rises caused by the vibration were measured at various load resistances. Efficiencies above 90% with load resistance were obtained from all the transformers. The voltage step-up ratio appeared to be proportional to the dot electrode area. A 14 W fluorescent lamp, T5, was successfully driven by all of the fabricated transformers. The transformer with ring/dot electrode area ratio of 4.85 exhibited the best properties in terms of output power, efficiency and characteristic temperature rise, 14.88 W, 98% and 5°C, respectively.

Cost saving synergistic shaft seal

NASA Technical Reports Server (NTRS)

Ludwig, L. P.; Strom, T. N.

1976-01-01

Segmented carbon rings, used to replace elastomeric seal lip, provide resistance to high temperatures generated in lubricating film. Machining and close manufacturing tolerances of conventional segmented seal are avoided by mounting segmented rings in elastomeric flex section.

SEALING MEANS FOR RELATIVELY ROTATABLE MEMBERS

DOEpatents

Skarstrom, C.S.

1960-10-25

A sealing means is offered for maintaining a seal between a pair of relatively rotatable members, panticularly between a rotating shaft and a stationary member surrounding the shaft. The sealing is accomplished by means of a flange extending outward radially on each of a plurality of sealing rings mounted on the rotating member which fit into annular grooves in the stationary member and are held in sealing relation therewith by means of spring rings. In addition, means are provided for passing a sealing gas through the seal sunfaces to prevent accumulation of lubricant and for scavenging any gas which may have leaked from the internal member into the seal area.

Viscoelastic properties of elastomeric materials for O-ring applications

NASA Technical Reports Server (NTRS)

Bower, Mark V.

1989-01-01

Redesign of the Space Shuttle Solid Rocket Booster necessitated re-evaluation of the material used in the field joint O-ring seals. This research project was established to determine the viscoelastic characteristics of five candidate materials. The five materials are: two fluorocarbon compounds, two nitrile compounds, and a silicon compound. The materials were tested in a uniaxial compression test to determine the characteristic relaxation functions. These tests were performed at five different temperatures. A master material curve was developed for each material from the experimental data. The results of this study are compared to tensile relaxation tests. Application of these results to the design analysis is discussed in detail.

Method of forming shrink-fit compression seal

NASA Technical Reports Server (NTRS)

Podgorski, T. J. (Inventor)

1977-01-01

A method for making a glass-to-metal seal is described. A domed metal enclosure having a machined seal ring is fitted to a glass post machined to a slight taper and to a desired surface finish. The metal part is then heated by induction in a vacuum. As the metal part heats and expands relative to the glass post, the metal seal ring, possessing a higher coefficient of expansion than the glass post, slides down the tapered post. Upon cooling, the seal ring crushes against the glass post forming the seal. The method results in a glass-to-metal seal possessing extremely good leak resistance, while the parts are kept clean and free of the contaminants.

High speed, self-acting shaft seal. [for use in turbine engines

NASA Technical Reports Server (NTRS)

Ludwig, L. P.; Hady, W. F. (Inventor)

1975-01-01

A high-speed, self-acting circumferential type shaft seal for use in turbine engines is disclosed. One or more conventional circumferential ring seals having a central aperture are mounted in a housing. In three of the four embodiments of the invention, a helical groove and one or more dam seals are cut in the inner cylindrical surface of the one or more ring seals. In a fourth embodiment, two or more lift pads are disposed in surface contact with the inner cylindrical surface of the seal rings. To the outside of the lift pads, two dam seals are cut in the inner cylindrical surface of two of the ring seals. In each of the embodiments, a net outward radial force was produced during rotation of the turbine causing the ring seals to lift out of contact with the turbine shaft to minimize wear of the ring seals.

Wafer-level hermetic vacuum packaging by bonding with a copper-tin thin film sealing ring

NASA Astrophysics Data System (ADS)

Akashi, Teruhisa; Funabashi, Hirofumi; Takagi, Hideki; Omura, Yoshiteru; Hata, Yoshiyuki

2018-04-01

A wafer-level hermetic vacuum packaging technology intended for use with MEMS devices was developed based on a copper-tin (CuSn) thin film sealing ring. To allow hermetic packaging, the shear strength of the CuSn thin film bond was improved by optimizing the pretreatment conditions. As a result, an average shear strength of 72.3 MPa was obtained and a cavity that had been hermetically sealed using wafer-level packaging (WLP) maintained its vacuum for 1.84 years. The total pressures in the cavities and the partial pressures of residual gases were directly determined with an ultra-low outgassing residual gas analyzer (RGA) system. Hermeticity was evaluated based on helium leak rates, which were calculated from helium pressures determined with the RGA system. The resulting data showed that a vacuum cavity following 1.84 years storage had a total pressure of 83.1 Pa, contained argon as the main residual gas and exhibited a helium leak rate as low as 1.67  ×  10-17 Pa · m3 s-1, corresponding to an air leak rate of 6.19  ×  10-18 Pa · m3 s-1. The RGA data demonstrate that WLP using a CuSn thin film sealing ring permits ultra-high hermeticity in conjunction with long-term vacuum packaging that is applicable to MEMS devices.

Hermetically sealed electrical feedthrough for high temperature secondary cells

DOEpatents

Knoedler, R.; Nelson, P.A.; Shimotake, H.; Battles, J.E.

1983-07-26

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

Hermetically sealed electrical feedthrough for high temperature secondary cells

DOEpatents

Knoedler, Reinhard; Nelson, Paul A.; Shimotake, Hiroshi; Battles, James E.

1985-01-01

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

Effect of CrO3 Sealing Time on Anodized A12024-T3

NASA Astrophysics Data System (ADS)

Korda, Akhmad A.; Hidayat, R. Z.

2016-08-01

The effect of CrO3 sealing time on anodized aluminum alloy has been investigated. A1 2024-T3 were used as substrate. Anodizing was carried out using chromic acid. CrO3 sealing was conducted in CrO3 solution for 30, 60, 90, 120 and 150 minutes. As comparison, other specimens were also prepared as anodized and boiled water sealing. Thickness of the coating was observed by optical microscope. Anodized and sealing layer was analyzed by X- ray diffraction. The hardness of as anodized, boiled water sealing and CrO3 sealing were compared. The highest hardness is achieved by CrO3 sealed specimen and followed by boiled water sealing and as anodized specimens. The longer the processes of CrO3 sealing the higher layer thickness and therefore the higher hardness of the oxide layer. The best resistance to electrolyte penetration is achieved by the CrO3 sealed specimen followed by boiled water sealed and as anodized specimens. The higher thickness of oxide layer, the higher the resistance against electrolyte penetration.

5.7  W cw single-frequency laser at 671  nm by single-pass second harmonic generation of a 17.2  W injection-locked 1342  nm Nd : YVO4 ring laser using periodically poled MgO : LiNbO3.

PubMed

Koch, Peter; Ruebel, Felix; Bartschke, Juergen; L'huillier, Johannes A

2015-11-20

We demonstrate a continuous wave single-frequency laser at 671.1 nm based on a high-power 888 nm pumped Nd:YVO4 ring laser at 1342.2 nm. Unidirectional operation of the fundamental ring laser is achieved with the injection-locking technique. A Nd:YVO4 microchip laser serves as the injecting seed source, providing a tunable single-frequency power of up to 40 mW. The ring laser emits a single-frequency power of 17.2 W with a Gaussian beam profile and a beam propagation factor of M2<1.1. A 60-mm-long periodically poled MgO-doped LiNbO3 crystal is used to generate the second harmonic in a single-pass scheme. Up to 5.7 W at 671.1 nm with a Gaussian shaped beam profile and a beam propagation factor of M2<1.2 are obtained, which is approximately twice the power of previously reported lasers. This work opens possibilities in cold atoms experiments with lithium, allowing the use of larger ensembles in magneto-optical traps or higher diffraction orders in atomic beam interferometers.

Stress and Sealing Performance Analysis of Containment Vessel

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

WU, TSU-TE

2005-05-24

This paper presents a numerical technique for analyzing the containment vessel subjected to the combined loading of closure-bolt torque and internal pressure. The detailed stress distributions in the O-rings generated by both the torque load and the internal pressure can be evaluated by using this method. Consequently, the sealing performance of the O-rings can be determined. The material of the O-rings can be represented by any available constitutive equation for hyperelastic material. In the numerical calculation of this paper, the form of the Mooney-Rivlin strain energy potential is used. The technique treats both the preloading process of bolt tightening andmore » the application of internal pressure as slow dynamic loads. Consequently, the problem can be evaluated using explicit numerical integration scheme.« less

Alcohol Dehydration on Monooxo W=O and Dioxo O=W=O Species

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

Li, Zhenjun; Smid, Bretislav; Kim, Yu Kwon

2012-08-16

The dehydration of 1-propanol on nanoporous WO3 films prepared via ballistic deposition at ~20 K has been investigated using temperature programmed desorption, infrared reflection absorption spectroscopy and density functional theory. The as deposited films are extremely efficient in 1-propanol dehydration to propene. This activity is correlated with the presence of dioxo O=W=O groups while monooxo W=O species are shown to be inactive. Annealing of the film induces densification that results in the loss of catalytic activity due to annihilation O=W=O species.

Application of the Wavy Mechanical Face Seal to Submarine Seal Design.

DTIC Science & Technology

1982-07-01

to Stainless Steel Bond Strength Tests. . . 31 3-1 Seal Design ...... .................... ... 54 3-2 Offset and Tilt Results...primer, Loctite Superbonder 420 with the addi- tion of two stainless steel rings for the inner and outer diam- eter of the carbon insert to give a...near zero clearance fit, and the use of the 3M 1838 B/A epoxy also with the same stainless steel rings. Static and dynamic tests on the seal under water

Age and sex composition of seals killed by polar bears in the eastern Beaufort Sea.

PubMed

Pilfold, Nicholas W; Derocher, Andrew E; Stirling, Ian; Richardson, Evan; Andriashek, Dennis

2012-01-01

Polar bears (Ursus maritimus) of the Beaufort Sea enter hyperphagia in spring and gain fat reserves to survive periods of low prey availability. We collected information on seals killed by polar bears (n=650) and hunting attempts on ringed seal (Pusa hispida) lairs (n=1396) observed from a helicopter during polar bear mark-recapture studies in the eastern Beaufort Sea in spring in 1985-2011. We investigated how temporal shifts in ringed seal reproduction affect kill composition and the intraspecific vulnerabilities of ringed seals to polar bear predation. Polar bears primarily preyed on ringed seals (90.2%) while bearded seals (Erignathus barbatus) only comprised 9.8% of the kills, but 33% of the biomass. Adults comprised 43.6% (150/344) of the ringed seals killed, while their pups comprised 38.4% (132/344). Juvenile ringed seals were killed at the lowest proportion, comprising 18.0% (62/344) of the ringed seal kills. The proportion of ringed seal pups was highest between 2007-2011, in association with high ringed seal productivity. Half of the adult ringed seal kills were ≥ 21 years (60/121), and kill rates of adults increased following the peak of parturition. Determination of sex from DNA revealed that polar bears killed adult male and adult female ringed seals equally (0.50, n=78). The number of hunting attempts at ringed seal subnivean lair sites was positively correlated with the number of pup kills (r(2) =0.30, P=0.04), but was not correlated with the number of adult kills (P=0.37). Results are consistent with decadal trends in ringed seal productivity, with low numbers of pups killed by polar bears in spring in years of low pup productivity, and conversely when pup productivity was high. Vulnerability of adult ringed seals to predation increased in relation to reproductive activities and age, but not gender.

Titanium sealing glasses and seals formed therefrom

DOEpatents

Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

1997-01-01

Alkaline-earth lanthanoborate sealing-glass compositions containing CaO, La.sub.2 O.sub.3, B.sub.2 O.sub.3, TiO.sub.2 and Al.sub.2 O.sub.3 in various combinations of mole-% are provided. These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys that have a high aqueous durability for component or device applications requiring exposure to moisture, water or body fluids. Particular applications of the titanium sealing-glass compositions include forming glass-to-metal seals for lithium batteries and implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

Shaft Seal Compensates for Cold Flow

NASA Technical Reports Server (NTRS)

Myers, W. N.; Hein, L. A.

1985-01-01

Seal components easy to install. Ring seal for rotating or reciprocating shafts spring-loaded to compensate for slow yielding (cold flow) of sealing material. New seal relatively easy to install because components preassembled, then installed in one piece.

Internal coaxial cable seal system

DOEpatents

Hall, David R.; Sneddon, Cameron; Dahlgren, Scott Steven; Briscoe, Michael A.

2006-07-25

The invention is a seal system for a coaxial cable and is placed within the coaxial cable and its constituent components. A series of seal stacks including load ring components and elastomeric rings are placed on load bearing members within the coaxial cable sealing the annular space between the coaxial cable and an electrical contact passing there through. The coaxial cable is disposed within drilling components to transmit electrical signals between drilling components within a drill string. The seal system can be used in a variety of downhole components, such as sections of pipe in a drill string, drill collars, heavy weight drill pipe, and jars.

An Arctic predator-prey system in flux: climate change impacts on coastal space use by polar bears and ringed seals.

PubMed

Hamilton, Charmain D; Kovacs, Kit M; Ims, Rolf A; Aars, Jon; Lydersen, Christian

2017-09-01

Climate change is impacting different species at different rates, leading to alterations in biological interactions with ramifications for wider ecosystem functioning. Understanding these alterations can help improve predictive capacity and inform management efforts designed to mitigate against negative impacts. We investigated how the movement and space use patterns of polar bears (Ursus maritimus) in coastal areas in Svalbard, Norway, have been altered by a sudden decline in sea ice that occurred in 2006. We also investigated whether the spatial overlap between polar bears and their traditionally most important prey, ringed seals (Pusa hispida), has been affected by the sea-ice decline, as polar bears are dependent on a sea-ice platform for hunting seals. We attached biotelemetry devices to ringed seals (n = 60, both sexes) and polar bears (n = 67, all females) before (2002-2004) and after (2010-2013) a sudden decline in sea ice in Svalbard. We used linear mixed-effects models to evaluate the association of these species to environmental features and an approach based on Time Spent in Area to investigate changes in spatial overlap between the two species. Following the sea-ice reduction, polar bears spent the same amount of time close to tidal glacier fronts in the spring but less time in these areas during the summer and autumn. However, ringed seals did not alter their association with glacier fronts during summer, leading to a major decrease in spatial overlap values between these species in Svalbard's coastal areas. Polar bears now move greater distances daily and spend more time close to ground-nesting bird colonies, where bear predation can have substantial local effects. Our results indicate that sea-ice declines have impacted the degree of spatial overlap and hence the strength of the predator-prey relationship between polar bears and ringed seals, with consequences for the wider Arctic marine and terrestrial ecosystems. Shifts in ecological

Titanium sealing glasses and seals formed therefrom

DOEpatents

Brow, R.K.; McCollister, H.L.; Phifer, C.C.; Day, D.E.

1997-12-02

Alkaline-earth lanthanoborate sealing-glass compositions containing CaO, La{sub 2}O{sub 3}, B{sub 2}O{sub 3}, TiO{sub 2} and Al{sub 2}O{sub 3} in various combinations of mole-% are provided. These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys that have a high aqueous durability for component or device applications requiring exposure to moisture, water or body fluids. Particular applications of the titanium sealing-glass compositions include forming glass-to-metal seals for lithium batteries and implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps). 2 figs.

Comparative hepatic in vitro depletion and metabolite formation of major perfluorooctane sulfonate precursors in Arctic polar bear, beluga whale, and ringed seal.

PubMed

Letcher, Robert J; Chu, Shaogang; McKinney, Melissa A; Tomy, Gregg T; Sonne, Christian; Dietz, Rune

2014-10-01

Perfluorooctane sulfonate (PFOS) has been reported to be among the most concentrated persistent organic pollutants in Arctic marine wildlife. The present study examined the in vitro depletion of major PFOS precursors, N-ethyl-perfluorooctane sulfonamide (N-EtFOSA) and perfluorooctane sulfonamide (FOSA), as well as metabolite formation using an assay based on enzymatically viable liver microsomes for three top Arctic marine mammalian predators, polar bear (Ursus maritimus), beluga whale (Delphinapterus leucas), and ringed seal (Pusa hispida), and in laboratory rat (Rattus rattus) serving as a general mammalian model and positive control. Rat assays showed that N-EtFOSA (38 nM or 150 ng mL(-1)) to FOSA metabolism was >90% complete after 10 min, and at a rate of 23 pmol min(-1) mg(-1) protein. Examining all species in a full 90 min incubation assay, there was >95% N-EtFOSA depletion for the rat active control and polar bear microsomes, ∼65% for ringed seals, and negligible depletion of N-EtFOSA for beluga whale. Concomitantly, the corresponding in vitro formation of FOSA from N-EtFOSA was also quantitatively rat≈polar bear>ringed seal>beluga whale. A lack of enzymatic ability and/or a rate too slow to be detected likely explains the lack of N-EtFOSA to FOSA transformation for beluga whale. In the same assays, the depletion of the FOSA metabolite was insignificant (p>0.01) and with no concomitant formation of PFOS metabolite. This suggests that, in part, a source of FOSA is the biotransformation of accumulated N-EtFOSA in free-ranging Arctic ringed seal and polar bear. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Rotatable seal assembly. [Patent application; rotating targets

DOEpatents

Logan, C.M.; Garibaldi, J.L.

1980-11-12

An assembly is provided for rotatably supporting a rotor on a stator so that vacuum chambers in the rotor and stator remain in communication while the chambers are sealed from ambient air, which enables the use of a ball bearing or the like to support most of the weight of the rotor. The apparatus includes a seal device mounted on the rotor to rotate therewith, but shiftable in position on the rotor while being sealed to the rotor as by an O-ring. The seal device has a flat face that is biased towards a flat face on the stator, and pressurized air is pumped between the faces to prevent contact between them while spacing them a small distance apart to avoid the inflow of large amounts of air between the faces and into the vacuum chambers.

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.

Radial forces in a misaligned radial face seal

NASA Technical Reports Server (NTRS)

Etsion, I.

1978-01-01

Radial forces on the primary seal ring of a flat misaligned seal are analyzed, taking into account the radial variation in seal clearance. An analytical solution for both hydrostatic and hydrodynamic effects is presented that covers the whole range from zero to full angular misalignment. The net radial force on the primary seal ring is always directed so as to produce a radial eccentricity which generates inward pumping. Although the radial force is usually very small, in some cases it may be one of the reasons for excessive leakage through both the primary and secondary seals of a radial face seal.

Radial forces in a misaligned radial face seal

NASA Technical Reports Server (NTRS)

Etsion, I.

1977-01-01

Radial forces on the primary seal ring of a flat misaligned seal are analyzed, taking into account the radial variation in seal clearance. An analytical solution for both hydrostatic and hydrodynamic effects is presented that covers the whole range from zero to full angular misalignment. The net radial force on the primary seal ring is always directed so as to produce a radial eccentricity which generates inward pumping. Although the radial force is usually very small, in some cases it may be one of the reasons for excessive leakage through both the primary and secondary seals of a radial face seal.

Small High-Speed Self-Acting Shaft Seals for Liquid Rocket Engines

NASA Technical Reports Server (NTRS)

Burcham, R. E.; Boynton, J. L.

1977-01-01

Design analysis, fabrication, and experimental evaluation were performed on three self-acting facetype LOX seal designs and one circumferential-type helium deal design. The LOX seals featured Rayleigh step lift pad and spiral groove geometry for lift augmentation. Machined metal bellows and piston ring secondary seal designs were tested. The helium purge seal featured floating rings with Rayleigh step lift pads. The Rayleigh step pad piston ring and the spiral groove LOX seals were successfully tested for approximately 10 hours in liquid oxygen. The helium seal was successfully tested for 24 hours. The shrouded Rayleigh step hydrodynamic lift pad LOX seal is feasible for advanced, small, high-speed oxygen turbopumps.

Self-acting shaft seals

NASA Technical Reports Server (NTRS)

Ludwig, L. P.

1978-01-01

Self-acting seals are described in detail. The mathematical models for obtaining a seal force balance and the equilibrium operating film thickness are outlined. Particular attention is given to primary ring response (seal vibration) to rotating seat face runout. This response analysis reveals three different vibration models with secondary seal friction being an important parameter. Leakage flow inlet pressure drop and affects of axisymmetric sealing face deformations are discussed. Experimental data on self-acting face seals operating under simulated gas turbine conditions are given. Also a spiral groove seal design operated to 244 m/sec (800 ft/sec) is described.

Nozzle seal

DOEpatents

Groff, Russell Dennis; Vatovec, Richard John

1978-06-11

In an illustrative embodiment of the invention, a nuclear reactor pressure vessel, having an internal hoop from which the heated coolant emerges from the reactor core and passes through to the reactor outlet nozzles, is provided with annular sealing members operatively disposed between the outlet nozzle and the hoop and partly within a retaining annulus formed in the hoop. The sealing members are biased against the pressure vessel and the hoop and one of the sealing members is provided with a piston type pressure ring sealing member which effectively closes the path between the inlet and outlet coolants in the region about the outlet nozzle establishing a leak-proof condition. Furthermore, the flexible responsiveness of the seal assures that the seal will not structurally couple the hoop to the pressure vessel.

Shaft seal assembly for high speed and high pressure applications

NASA Technical Reports Server (NTRS)

Hadt, W. F.; Ludwig, L. P. (Inventor)

1979-01-01

A seal assembly is provided for reducing the escape of fluids from between a housing and a shaft rotably mounted in the housing. The seal assembly comprises a pair of seal rings resiliently connected to each other and disposed in side-by-side relationship. In each seal ring, both the internal bore surface and the radial face which faces away from the other seal ring are provided with a plurality of equi-spaced recesses. The seal faces referred to are located adjacent a seating surface of the housing. Under normal operating conditions, the seal assembly is stationary with respect to the housing, and the recesses generate life, keep the assembly spaced from the rotating shaft and allow slip therebetween. The seal assembly can seize on the shaft, and slip will then occur between the radial faces and the housing.

Development of helicopter transmission seals, task 2

NASA Technical Reports Server (NTRS)

Hayden, T. S.; Keller, C. H., Jr.

1973-01-01

High speed helicopter transmission seal concepts were designed, fabricated and tested. The concepts were a dual element split ring seal and a circumferential seal. The tests were performed in a rig using an actual input quill assembly. The test conditions were selected to simulate transmission operation and were 230 F oil temperature, and a sliding speed of 9400 ft/min. The split ring seal exhibited gross leakage and was considered unsatisfactory, while the circumferential seal leakage was less than 1 c.c./hour; this leakage is within acceptable limits. The circumferential seal wear was only to .0005 inches during a 100 hour run (40 starts and stops). During a 40 hour contamination test (mesh silica flour) the seal total wear was a maximum of .004 inches. This wear is considered acceptable.

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.

Mercury trends in ringed seals (Phoca hispida) from the western Canadian Arctic since 1973: associations with length of ice-free season.

PubMed

Gaden, A; Ferguson, S H; Harwood, L; Melling, H; Stern, G A

2009-05-15

We examined a unique time series of ringed seal (Phoca hispida) samples collected from a single location in the western Canadian Arctic between 1973 and 2007 to test for changes in total mercury (THg) in muscle tissue associated with (1) year and (2) length of ice-free season. We found no temporal trend with muscle THg whereas a curvilinear relationship existed with the length of ice-free season: seals attaimed higher THg in short (2 months) and long (5 months) ice-free seasons. delta 15N and delta13C in muscle tissue did not illustrate significant trends with ice-free days. We estimated that the turnover time of THg in muscle was about twice as long as stable isotope turnover in muscle, possibly explaining the lack of trend with stable isotopes in association with ice-free duration. Our discussion explains how summer environmental conditions may influence the composition of prey (mercury exposure) available to ringed seals. Results offer insight into how marine mammals may respond to directional changes in the Arctic ice-free season.

Mainshaft seals for small gas turbine engines

NASA Technical Reports Server (NTRS)

Ludwig, L. P.; Lynwander, P.

1974-01-01

An experimental evaluation of mainshaft seals for small gas turbine engines was conducted with shaft speeds to 213 m/s (700 ft/sec), air pressures to 148 Newtons per square centimeter abs. (215 psia), and air temperatures to 412k(282 F). A radial face seal incorporating self-acting geometry for lift augmentation was evaluated. In addition, three conventional carbon seal types (face, circumferential segmented, and rotating ring) were run for comparison. Test results indicated that the conventional seals used in this evaluation may not be satisfactory in future advanced engines because of excessive air leakage. On the other hand, the self-acting face seal was shown to have the potential capability of limiting leakages to one-half that of the conventional face seals and one-fifth that of conventional ring seals. A 150-hour endurance test of the self-acting face seal was conducted.

Influence of Polycarboxylate Superplasticizers on Rheological Properties of Cement Slurries Used in Drilling Technologies / Wpływ Superplastyfikatorów Z Grupy Polikarboksylanów Na Właściwości Reologiczne Zaczynów Cementowych Stosowanych W Technologiach Wiertniczych

NASA Astrophysics Data System (ADS)

Stryczek, Stanisław; Wiśniowski, Rafał; Gonet, Andrzej; Złotkowski, Albert; Ziaja, Jan

2013-09-01

Sealing slurries, mainly the cement-based ones, are concentrated dispersive systems, containing solid particles of considerably developed specific surface. Rheologically, such systems are very complex. This also stems from the fact that the rheological properties have a significant effect on: • additives and admixtures modifying technological properties of fresh and set slurries, • chemically complex mechanism of hydration in a slurry in a function of time. Special attention should paid to plasticizing (plasticizers PL) and liquefying (traditional and new- -generation superplasticizers SP) admixtures affecting the modification and optimization of rheological properties of fresh cement slurries as far as providing efficiency of sealing of casing pipes is concerned. Laboratory analyses were focused on proving the following thesis: properly selected type of superplasticizer [by BASF Polska Sp.z o.o. (The Chemical Company) - Admixtures for Concrete Division] advantageously affects the rheological parameters of sealing slurry based on metallurgical cement CEM III /A 32,5. The following variables were used in the analyses: • type of superplasticizer, • type of batch fluid. The laboratory experiments were made on superplasticizers produced by BASF: • SKY 501, • SKY 503, • SKY 591, • ACE 430, • Glenium 115. The superplasticizer concentration in the slurry was 0.5 wt% (as compared with mass of dry cement). Water to cement ratio for the analyzed sealing slurries was equal to 0.5. The sealing slurries were made of metallurgical cement CEM III/A 32,5 N-LH/HSR/N Lafarge Cement S.A. in Małogoszcz. Zaczyny uszczelniające, a zwłaszcza typu cementowego, są skoncentrowanymi układami dyspersyjnymi, zawierającymi cząstki stałe o znacznie rozwiniętej powierzchni właściwej. Układy takie pod względem reologicznym należą do niezwykle złożonych. Wynika to między innymi z faktu, że na właściwości reologiczne w sposób istotny wpływają: • dodatki i

Development of seal ring carbon-graphite materials (tasks 5, 6, and 7)

NASA Technical Reports Server (NTRS)

Fechter, N. J.; Petrunich, P. S.

1972-01-01

Carbon-graphite seal ring bodies for operation at air temperatures to 1300 F(704 C) were manufactured from three select formulations. Mechanical and thermal properties, porosities, and oxidation rates were measured. The results have shown that: (1) Major property improvements anticipated from the screening studies were not realized because of processing problems associated with the scale-up in material size and probable deterioration of a phenolic resin binder; (2) the mechanical properties of a phenolic resin-bonded, carbon-graphite material can be improved by applying high pressure during carbonization; and (3) the textile form of graphite fiber used as the minor filler component in a carbon-graphite material can beneficially affect mechanical properties.

Hermetic Glass-To-Metal Seal For Instrumentation Window

NASA Technical Reports Server (NTRS)

Hill, Arthur J.

1992-01-01

Proposed mounting scheme for optical element of instrumentation window in pressure vessel ensures truly hermetic seal while minimizing transmission of stress to optical element. Brazed metal seal superior to conventional gaskets of elastomer, carbon, asbestos, or other material compressed between optical element and wall of vessel. Concentric brazed joints in proposed seal bond metal ring to wall of vessel and to optical element. U-shaped cross section allows ring to flex under pressure.

Performance of a shaft seal system for the LE-7 rocket engine oxidizer turbopump

NASA Astrophysics Data System (ADS)

Oike, Mamoru; Nosaka, Masataka; Kikuchi, Masataka; Watanabe, Yoshiaki

An experimental study on a rotating-shaft seal system for a high-pressure liquid oxygen (LOX) turbopump has been conducted to develop the LE-7 engine for the Japanese H-II launch vehicle. The LOX turbopump rotating-shaft seal system, which prevents LOX (4.9 MPa) and the high-pressure turbine-drive gas (16.6 MPa, 970 K) from mixing during high-speed operations (18,000 to 20,000 rpm), consists of the following seals: an LOX seal comprising a floating-ring and a wear-ring, a turbine gas seal comprising two floating-rings, and a helium purge seal comprising two segmented circumferential seal-rings. This report describes experimental and observational results concerning the rotating-shaft seal system obtained in the LOX turbopump operations and the seal tests. Based on comparisons between the measurements and the analytical results, sealing characteristics of the seal system are discussed. Inspections of the sealing surfaces after the engine firing tests demonstrated that the LOX turbopump rotating-shaft seal system has sufficient durability for use in the LE-7 engine for the H-II launch vehicle.

An Internal Coaxil Cable Seal System

DOEpatents

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

2004-12-23

The invention is a seal system for a coaxial cable more specifically an internal seal system placed within the coaxial cable and its constituent components. A series of seal stacks including flexible rigid rings and elastomeric rings are placed on load bearing members within the coaxial cable. The current invention is adapted to seal the annular space between the coaxial cable and an electrical contact passing there through. The coaxial cable is disposed within drilling components to transmit electrical signals between drilling components within a drill string. During oil and gas exploration, a drill string can see a range of pressures and temperatures thus resulting in multiple combinations of temperature and pressure and increasing the difficulty of creating a robust seal for all combinations. The seal system can be used in a plurality of downhole components, such as sections of pipe in a drill string, drill collars, heavy weight drill pipe, and jars.

Advanced helium purge seals for Liquid Oxygen (LOX) turbopumps

NASA Technical Reports Server (NTRS)

Shapiro, Wilbur; Lee, Chester C.

1989-01-01

Program objectives were to determine three advanced configurations of helium buffer seals capable of providing improved performance in a space shuttle main engine (SSME), high-pressure liquid oxygen (LOX) turbopump environment, and to provide NASA with the analytical tools to determine performance of a variety of seal configurations. The three seal designs included solid-ring fluid-film seals often referred to as floating ring seals, back-to-back fluid-film face seals, and a circumferential sectored seal that incorporated inherent clearance adjustment capabilities. Of the three seals designed, the sectored seal is favored because the self-adjusting clearance features accommodate the variations in clearance that will occur because of thermal and centrifugal distortions without compromising performance. Moreover, leakage can be contained well below the maximum target values; minimizing leakage is important on the SSME since helium is provided by an external tank. A reduction in tank size translates to an increase in payload that can be carried on board the shuttle. The computer codes supplied under this program included a code for analyzing a variety of gas-lubricated, floating ring, and sector seals; a code for analyzing gas-lubricated face seals; a code for optimizing and analyzing gas-lubricated spiral-groove face seals; and a code for determining fluid-film face seal response to runner excitations in as many as five degrees of freedom. These codes proved invaluable for optimizing designs and estimating final performance of the seals described.

Assessment of neurotoxic effects of mercury in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) from the Canadian Arctic.

PubMed

Krey, Anke; Ostertag, Sonja K; Chan, Hing Man

2015-03-15

Marine mammals are indicator species of the Arctic ecosystem and an integral component of the traditional Inuit diet. The potential neurotoxic effects of increased mercury (Hg) in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) are not clear. We assessed the risk of Hg-associated neurotoxicity to these species by comparing their brain Hg concentrations with threshold concentrations for toxic endpoints detected in laboratory animals and field observations: clinical symptoms (>6.75 mg/kg wet weight (ww)), neuropathological signs (>4 mg/kg ww), neurochemical changes (>0.4 mg/kg ww), and neurobehavioral changes (>0.1mg/kg ww). The total Hg (THg) concentrations in the cerebellum and frontal lobe of ringed seals and polar bears were <0.5mg/kg ww, whereas the average concentration in beluga whale brain was >3mg/kg ww. Our results suggest that brain THg levels in polar bears are below levels that induce neurobehavioral effects as reported in the literature, while THg concentrations in ringed seals are within the range that elicit neurobehavioral effects and individual ringed seals exceed the threshold for neurochemical changes. The relatively high THg concentration in beluga whales exceeds all of the neurotoxicity thresholds assessed. High brain selenium (Se):Hg molar ratios were observed in all three species, suggesting that Se could protect the animals from Hg-associated neurotoxicity. This assessment was limited by several factors that influence neurotoxic effects in animals, including: animal species; form of Hg in the brain; and interactions with modifiers of Hg-associated toxicity, such as Se. Comparing brain Hg concentrations in wildlife with concentrations of appropriate laboratory studies can be used as a tool for risk characterization of the neurotoxic effects of Hg in Arctic marine mammals. Copyright © 2014 Elsevier B.V. All rights reserved.

Fluorosilicone and silicone o-ring aging study.

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

Bernstein, Robert; Gillen, Kenneth T.

2007-10-01

Fluorosilicone o-ring aging studies were performed. These studies examined the compressive force loss of fluorosilicone o-rings at accelerated (elevated) temperatures and were then used to make predictions about force loss at room temperature. The results were non-Arrhenius with evidence for a lowering in Arrhenius activation energies as the aging temperature was reduced. The compression set of these fluorosilicone o-rings was found to have a reasonably linear correlation with the force loss. The aging predictions based on using the observed curvature of the Arrhenius aging plots were validated by field aged o-rings that yielded degradation values reasonably close to the predictions.more » Compression set studies of silicone o-rings from a previous study resulted in good correlation to the force loss predictions for the fluorosilicone o-rings from this study. This resulted in a preliminary conclusion that an approximately linear correlation exists between compression set and force decay values for typical fluorosilicone and silicone materials, and that the two materials age at similar rates at low temperatures. Interestingly, because of the observed curvature of the Arrhenius plots available from longer-term, lower temperature accelerated exposures, both materials had faster force decay curves (and correspondingly faster buildup of compression set) at room temperature than anticipated from typical high-temperature exposures. A brief study on heavily filled conducting silicone o-rings resulted in data that deviated from the linear relationship, implying that a degree of caution must be exercised about any general statement relating force decay and compression set.« less

High temperature autoclave vacuum seals

NASA Technical Reports Server (NTRS)

Hoffman, J. R.; Simpson, W. G.; Walker, H. M.

1971-01-01

Aluminum sheet forms effective sealing film at temperatures up to 728 K. Soft aluminum wire rings provide positive seal between foil and platen. For applications at temperatures above aluminum's service temperature, stainless steel is used as film material and copper wire as sealant.

Energy efficient face seal

NASA Technical Reports Server (NTRS)

Sehnal, J.; Sedy, J.; Etsion, I.; Zobens, A.

1982-01-01

Torque, face temperature, leakage, and wear of a flat face seal were compared with three coned face seals at pressures up to 2758 kPa and speeds up to 8000 rpm. Axial movement of the mating seal parts was recorded by a digital data acquisition system. The coning of the tungsten carbide primary ring ranged from .51 micro-m to 5.6 micro-m. The torque of the coned face seal balanced to 76.3% was an average 42% lower, the leakage eleven times higher, than that of the standard flat face seal. The reduction of the balance of the coned face seal to 51.3% resulted by decreasing the torque by an additional 44% and increasing leakage 12 to 230 times, depending on the seal shaft speed. No measurable wear was observed on the face of the coned seals.

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.

Dynamic response of film thickness in spiral-groove face seals

NASA Technical Reports Server (NTRS)

Dirusso, E.

1985-01-01

Tests were performed on an inward- and an outward-pumping spiral-groove face seal to experimentally determine the film thickness response to seal seat motions and to gain insight into the effect of secondary seal friction on film thickness behavior. Film thickness, seal seat axial motion, seal frictional torque, and film axial load were recorded as functions of time. The experiments revealed that for sinusoidal axial oscillations of the seal seat, the primary ring followed the seal seat motion very well. For a skewed seal seat, however, the primary ring did not follow the seal seat motion, and load-carrying capacity was degraded. Secondary seal friction was varied over a wide range to determine its effect on film thickness dynamics. The seals were tested with ambient air at room temperature and atmospheric pressure as the fluid medium. The test speed ranged from 7000 to 20,000 rpm. Seal tangential velocity ranged from 34 to 98 m/sec (113 to 323 ft/sec).

W/O/W multiple emulsions with diclofenac sodium.

PubMed

Lindenstruth, Kai; Müller, Bernd W

2004-11-01

The disperse oil droplets of W/O/W multiple emulsions contain small water droplets, in which drugs could be incorporated, but the structure of these emulsions is also the reason for possible instability. Due to the middle oil phase which acts as a 'semipermeable' membrane the passage of water across the oil phase can take place. However, the emulsions have been produced in a two-step-production process so not only the leakage of encapsulated drug molecules out of the inner water phase during storage but also a production-induced reduction of the encapsulation rate should be considered. The aim of this study was to ascertain how far the production-induced reduction of the encapsulation rate relates to the size of inner water droplets and to evaluate the relevance of multiple emulsions as drug carrier for diclofenac sodium. Therefore multiple emulsions were produced according to a central composite design. During the second production step it was observed that the parameters pressure and temperature have an influence on the size of the oil droplets in the W/O/W multiple emulsions. Further experiments with different W/O emulsions resulted in W/O/W multiple emulsions with different encapsulation rates of diclofenac sodium, due to the different sizes of the inner water droplets, which were obtained in the first production step.

Characteristics of Elastomer Seals Exposed to Space Environments

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; deGroh, Henry, III; Dunlap, Patrick H., Jr.; Finkbeiner, Joshua R.; Steinetz, Bruce M.; Bastrzyk, Marta B.; Oswald, Jay J.; Banks, Bruce A.; Dever, Joyce A.; Miller, Sharon K.;

Face-seal lubrication: 1: Proposed and published models

NASA Technical Reports Server (NTRS)

Ludwig, L. P.

1976-01-01

The numerous published theories on the mechanism of hydrodynamic lubrication of face seals were reviewed. These theories employ either an inclined-slider-bearing macrogeometry or an inclined-slider-bearing microgeometry to produce hydrodynamic pressure that separates the surfaces of the primary seal. Secondary seal friction and primary ring inertia effects are not considered. Hypothetical seal operating models were devised to include secondary seal friction and primary ring inertia effects. It was hypothesized that these effects induce relative angular misalinement of the primary seal faces and that this misalinement is, in effect, an inclined slider macrogeometry. Stable running was postulated for some of these hypothetical operating models. In others, periodic loss of hydrodynamic lubrication was postulated to be possible with certain combinations of waviness and angular misalinement. Application of restrictions that apply to seal operation led to a hydrodynamic governing equation for the new model that is a two-dimensional, time-dependent Reynolds equation with the short-bearing approximation.

A study of Solar-Enso correlation with southern Brazil tree ring index (1955- 1991)

NASA Astrophysics Data System (ADS)

Rigozo, N.; Nordemann, D.; Vieira, L.; Echer, E.

The effects of solar activity and El Niño-Southern Oscillation on tree growth in Southern Brazil were studied by correlation analysis. Trees for this study were native Araucaria (Araucaria Angustifolia)from four locations in Rio Grande do Sul State, in Southern Brazil: Canela (29o18`S, 50o51`W, 790 m asl), Nova Petropolis (29o2`S, 51o10`W, 579 m asl), Sao Francisco de Paula (29o25`S, 50o24`W, 930 m asl) and Sao Martinho da Serra (29o30`S, 53o53`W, 484 m asl). From these four sites, an average tree ring Index for this region was derived, for the period 1955-1991. Linear correlations were made on annual and 10 year running averages of this tree ring Index, of sunspot number Rz and SOI. For annual averages, the correlation coefficients were low, and the multiple regression between tree ring and SOI and Rz indicates that 20% of the variance in tree rings was explained by solar activity and ENSO variability. However, when the 10 year running averages correlations were made, the coefficient correlations were much higher. A clear anticorrelation is observed between SOI and Index (r=-0.81) whereas Rz and Index show a positive correlation (r=0.67). The multiple regression of 10 year running averages indicates that 76% of the variance in tree ring INdex was explained by solar activity and ENSO. These results indicate that the effects of solar activity and ENSO on tree rings are better seen on long timescales.

36 CFR 223.88 - Bidding methods.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 2 2013-07-01 2013-07-01 false Bidding methods. 223.88... Sale Contracts Advertisement and Bids § 223.88 Bidding methods. (a) Competitive sales of National Forest timber shall be offered through either sealed or oral auction bidding. The method chosen for each...

36 CFR 223.88 - Bidding methods.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 2 2012-07-01 2012-07-01 false Bidding methods. 223.88... Sale Contracts Advertisement and Bids § 223.88 Bidding methods. (a) Competitive sales of National Forest timber shall be offered through either sealed or oral auction bidding. The method chosen for each...

36 CFR 223.88 - Bidding methods.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 2 2014-07-01 2014-07-01 false Bidding methods. 223.88... Sale Contracts Advertisement and Bids § 223.88 Bidding methods. (a) Competitive sales of National Forest timber shall be offered through either sealed or oral auction bidding. The method chosen for each...

36 CFR 223.88 - Bidding methods.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 2 2011-07-01 2011-07-01 false Bidding methods. 223.88... Sale Contracts Advertisement and Bids § 223.88 Bidding methods. (a) Competitive sales of National Forest timber shall be offered through either sealed or oral auction bidding. The method chosen for each...

Composite correlation filter for O-ring detection in stationary colored noise

NASA Astrophysics Data System (ADS)

Hassebrook, Laurence G.

2009-04-01

O-rings are regularly replaced in aircraft and if they are not replaced or if they are installed improperly, they can result in catastrophic failure of the aircraft. It is critical that the o-rings be packaged correctly to avoid mistakes made by technicians during routine maintenance. For this reason, fines may be imposed on the o-ring manufacturer if the o-rings are packaged incorrectly. That is, a single o-ring must be packaged and labeled properly. No o-rings or more than one o-ring per package is not acceptable. We present an industrial inspection system based on real-time composite correlation filtering that has successfully solved this problem in spite of opaque paper o-ring packages. We present the system design including the composite filter design.

Nanoscale modulations in (KLa)(CaW)O-6 and (NaLa)(CaW)O-6

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

Licurse, Mark; Borisevich, Albina Y; Davies, Peter

2012-01-01

Complex nanoscale modulations are identified in two new A-site ordered perovskites, (KLa)(CaW)O{sub 6} and (NaLa)(CaW)O{sub 6}. In (KLa)(CaW)O{sub 6}, selected-area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM) show an incommensurate nanocheckerboard modulation with {approx}9.4 x 9.4 a{sub p} periodicity (a{sub p} {approx} 4 {angstrom} for the cubic perovskite aristotype). For (NaLa)(CaW)O{sub 6} a one-dimensional modulation is observed with a {approx}16(1 1 0)a{sub p} repeat; the <1 1 0> orientation of the nanostripes is different from the <1 0 0> stripes observed in other mixed A-site systems. Studies using high temperature x-ray diffraction suggest the formation of the complexmore » modulations is associated with small deviations from the ideal 1:1:1:1 stoichiometry of the (A{sup +}La{sup 3+})(CaW)O{sub 6} phases. Z-contrast images acquired on an aberration-corrected microscope provide evidence for deviations from stoichiometry with a {approx}1:15 periodic arrangement of La{sub 4/3}(CaW)O{sub 6}:(NaLa)(CaW)O{sub 6} nano-phases.« less

Performance testing of elastomeric seal materials under low and high temperature conditions: Final report

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

BRONOWSKI,DAVID R.

The US Department of Energy Offices of Defense Programs and Civilian Radioactive Waste Management jointly sponsored a program to evaluate elastomeric O-ring seal materials for radioactive material shipping containers. The report presents the results of low- and high-temperature tests conducted on 27 common elastomeric compounds.

High-resolution 17O double-rotation NMR characterization of ring and non-ring oxygen in vitreous B2O3.

PubMed

Wong, Alan; Howes, Andy P; Parkinson, Ben; Anupõld, Tiit; Samoson, Ago; Holland, Diane; Dupree, Ray

2009-08-28

The application of double rotation (DOR) NMR to crystalline materials (both inorganic and organic) has made tremendous strides in providing site-specific information about materials in recent years. However (17)O DOR has yet to demonstrate its potential in disordered materials such as glasses. In the present study, we have successfully recorded high resolution (17)O DOR spectra of vitreous B(2)O(3) (v-B(2)O(3)), a highly effective glass-forming oxide of considerable technological importance. Two distinct oxygen sites are resolved and a complete set of (17)O NMR parameters were determined from the DOR spectra. These were assigned to oxygen atoms in the planar boroxol ring [B(3)O(6)] and in the non-boroxol [BO(3)] groups which share oxygen with the ring boron atoms. This assignment was based on the similarity of all of their (17)O parameters with those found by DFT calculation for caesium enneaborate, Cs(2)O.9B(2)O(3), which has two boroxol rings in its structure. The boroxol ring oxygens have a more positive chemical shift, a larger shift anisotropy and a smaller electric field gradient than non ring oxygens (O(R): delta(iso) = 100 +/- 1 ppm, span = 180 +/- 20 ppm, skew = -0.4 +/- 0.1, P(q) = 5.0 +/- 0.2 MHz; O(NR): delta(iso) = 86 +/- 1 ppm, span = 100 +/- 20 ppm, skew = 0.1 +/- 0.1, P(q) = 5.7 +/- 0.2 MHz). The relative proportions of the two sites in v-B(2)O(3) are approximately 1 : 1, as expected if all three boron atoms in the boroxol ring are each connected to one oxygen in a linking [BO(3)] group and there are very few [BO(3)]-[BO(3)] linkages. We see no evidence for a third oxygen site such as has been reported in an earlier study of v-B(2)O(3). This work demonstrates the potential of (17)O DOR to provide site-specific information in disordered materials.

Preliminary investigation and application of alternate dry gas seal face materials{copyright}

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

Evenson, R.; Peterson, R.; Hanson, R.

1994-01-01

Traditional seal mating ring materials such as tungsten carbide (WC) are commonly used in high pressure centrifugal gas compressor dry gas (gas lubricating film) seal applications. Although these materials possess desirable properties for minimizing thermal distortion and deformation when subjected to pressure and centrifugal force, they have low toughness, i.e., they are brittle and have poor resistance to thermal shock. It has been found that these materials are easily heat checked during seal face touchdown. Heat checking as well as other crack indications inherent in these materials can quickly propagate, resulting in a catastrophic seal ring failure. In this paper,more » an investigation of alternate seal face materials is described. Two ductile, nitrided, low ferrous materials proved to be readily manufacturable into dry gas seal rings and performed comparably to tungsten carbide in natural gas service. 10 refs., 13 figs., 5 tabs.« less

Analysis and Design of a Double-Divert Spiral Groove Seal

NASA Technical Reports Server (NTRS)

Zheng, Xiaoqing; Berard, Gerald

2007-01-01

This viewgraph presentation describes the design and analysis of a double spiral groove seal. The contents include: 1) Double Spiral Design Features; 2) Double Spiral Operational Features; 3) Mating Ring/Rotor Assembly; 4) Seal Ring Assembly; 5) Insert Segment Joints; 6) Rotor Assembly Completed Prototype Parts; 7) Seal Assembly Completed Prototype Parts; 8) Finite Element Analysis; 9) Computational Fluid Dynamics (CFD) Analysis; 10) Restrictive Orifice Design; 11) Orifice CFD Model; 12) Orifice Results; 13) Restrictive Orifice; 14) Seal Face Coning; 15) Permanent Magnet Analysis; 16) Magnetic Repulsive Force; 17) Magnetic Repulsive Test Results; 18) Spin Testing; and 19) Testing and Validation.

Self-acting and hydrodynamic shaft seals

NASA Technical Reports Server (NTRS)

Ludwig, L. P.

1973-01-01

Self-acting and hydrodynamic seals are described. The analytical procedures are outlined for obtaining a seal force balance and the operating film thickness. Particular attention is given to primary ring response (seal vibration) to rotating seat face runout. This response analysis revealed three different vibration modes. Proposed applications of self-acting seals in gas turbine engines and in rocket vehicle turbopumps are described. Also experimental data on self-acting face seals operating under simulated gas turbine conditions are given; these data show the feasibility of operating the seal at conditions of 345 newtons per square centimeter (500 psi) and 152 meters per second (500 ft/sec) sliding speed.

Foil Face Seal Testing

NASA Technical Reports Server (NTRS)

Munson, John

2009-01-01

In the seal literature you can find many attempts by various researchers to adapt film riding seals to the gas turbine engine. None have been successful, potential distortion of the sealing faces is the primary reason. There is a film riding device that does accommodate distortion and is in service in aircraft applications, namely the foil bearing. More specifically a foil thrust bearing. These are not intended to be seals, and they do not accommodate large axial movement between shaft & static structure. By combining the 2 a unique type of face seal has been created. It functions like a normal face seal. The foil thrust bearing replaces the normal primary sealing surface. The compliance of the foil bearing allows the foils to track distortion of the mating seal ring. The foil seal has several perceived advantages over existing hydrodynamic designs, enumerated in the chart. Materials and design methodology needed for this application already exist. Also the load capacity requirements for the foil bearing are low since it only needs to support itself and overcome friction forces at the antirotation keys.

The commercial harvest of ice-associated seals in the Sea of Okhotsk, 1972-1994

PubMed Central

Somov, Aleksandr G.; Burkanov, Vladimir N.; Laidre, Kristin L.; Boveng, Peter L.

2017-01-01

Sealing log books from 75 out of 79 commercial harvest cruises carried out between 1972 and 1994 in the Sea of Okhotsk, Russia, were analyzed to describe spatial and temporal allocation of ice-associated seal harvest effort, species composition of catches, total harvest rates, and related parameters for species including ringed (Pusa hispida), ribbon (Histriophoca fasciata), bearded (Erignathus barbatus) and spotted (Phoca largha) seal. Variations in catch per unit effort were explored in relation to year, sea ice conditions, day of the year, and geographic location. In most years, the harvest was predominantly represented by ringed seals (mean = 0.43, range 0.25–0.67), followed by ribbon (mean = 0.31, range 0.15–0.43), spotted (mean = 0.19, range 0.11–0.35) and bearded seals (mean = 0.07, range 0.03–0.14). The struck-and-lost percentages were as high as 30–35% for ringed, bearded and spotted seals and 15–20% for ribbon seals. Catch per unit effort (number of seals/skiff*day) for ringed, ribbon, and spotted seals had a similar seasonal pattern with a distinct spike in catches for spotted seals in the first week of May, for ribbon seals in the last week of May, and for ringed seals in the second week of June. Catches of bearded seals showed a less pronounced temporal structure with a gradual increase toward the end of the harvest season in the majority of years. Spatial distribution of harvest effort followed closely with seal distribution obtained from aerial surveys. These data could be used as a source of information on seal herd location throughout the breeding and molting seasons and for more complex demographic or life-table models. We did not find any evidence of the decline of catch per unit effort over the study period. Timely introduction of state regulations and efficient harvest management apparently prevented severe depletion of ice-associated seal populations in the Sea of Okhotsk during the periods of their intense exploitation. PMID

The commercial harvest of ice-associated seals in the Sea of Okhotsk, 1972-1994.

PubMed

Trukhanova, Irina S; Grachev, Aleksey I; Somov, Aleksandr G; Burkanov, Vladimir N; Laidre, Kristin L; Boveng, Peter L

2017-01-01

Sealing log books from 75 out of 79 commercial harvest cruises carried out between 1972 and 1994 in the Sea of Okhotsk, Russia, were analyzed to describe spatial and temporal allocation of ice-associated seal harvest effort, species composition of catches, total harvest rates, and related parameters for species including ringed (Pusa hispida), ribbon (Histriophoca fasciata), bearded (Erignathus barbatus) and spotted (Phoca largha) seal. Variations in catch per unit effort were explored in relation to year, sea ice conditions, day of the year, and geographic location. In most years, the harvest was predominantly represented by ringed seals (mean = 0.43, range 0.25-0.67), followed by ribbon (mean = 0.31, range 0.15-0.43), spotted (mean = 0.19, range 0.11-0.35) and bearded seals (mean = 0.07, range 0.03-0.14). The struck-and-lost percentages were as high as 30-35% for ringed, bearded and spotted seals and 15-20% for ribbon seals. Catch per unit effort (number of seals/skiff*day) for ringed, ribbon, and spotted seals had a similar seasonal pattern with a distinct spike in catches for spotted seals in the first week of May, for ribbon seals in the last week of May, and for ringed seals in the second week of June. Catches of bearded seals showed a less pronounced temporal structure with a gradual increase toward the end of the harvest season in the majority of years. Spatial distribution of harvest effort followed closely with seal distribution obtained from aerial surveys. These data could be used as a source of information on seal herd location throughout the breeding and molting seasons and for more complex demographic or life-table models. We did not find any evidence of the decline of catch per unit effort over the study period. Timely introduction of state regulations and efficient harvest management apparently prevented severe depletion of ice-associated seal populations in the Sea of Okhotsk during the periods of their intense exploitation.

Ring-opening of {sigma}-thienyl and {sigma}-furyl ligands at ditungsten (M=M) centers

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

Chisholm, M.H.; Haubrich, S.T.; Huffman, J.C.

1997-02-19

A series of compounds of formula 1,2-M{sub 2}({sigma}-Th){sub 2}(NMe{sub 2}){sub 4}, 1,has been prepared, where M = Mo and/or W and Th = 2-thienyl[2-Th], 3-thienyl[3-Th], 5-methyl-2-thienyl[2,5-MeTh], and 2-benzothienyl[2-BTh]. Addition of {sup t}BuOH or CF{sub 3}Me{sub 2}COH to hydrocarbon solutions of 1, where M = W, lead to ring-opened products, 2, when the thienyl ligand is attached via the 2-carbon position. No ring-opening occurs for 3-thienyl derivatives. W{sub 2}(OR){sub 5}({mu}-CCH{sub 2}CHCHS)({sigma}-2-Th), 2, where one of the 2-thienyl rings has been opened, has been fully characterized and shown to be derived from a ring-opened {mu}-vinylidene intermediate W{sub 24}/(O{sup t}Bu){sub 4}({mu}-CCHCHCHS)({sigma}-2-Th). The compoundmore » W{sub 2}({sigma}-2-Fu){sub 2}(NMe{sub 2}){sub 4} was prepared and characterized (2-Fu = 2-furyl) and shown to undergo ring-opening in its reaction with {sup t}BuOH to give W{sub 2}(O{sup t}Bu){sub 5}({mu}-CCH{sub 2}CHCHO)({sigma}-2-Fu), 4, in an analogous manner to the 2-Th complex. The complexes 1 (M = W, 2-Th), 2, 3, and 4 have been characterized by single crystal X-ray studies. The results described herein are compared to other ring-opening reactions of S, N, and O organic heterocyclic compounds as models for the activation of S, N, and O containing fossil fuels in hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and hydrodeoxygenation (HDO) processes. 36 refs., 7 figs., 5 tabs.« less

Seal Technology for Liquid Oxygen (LOX) Turbopumps

NASA Technical Reports Server (NTRS)

Shapiro, Wilbur; Hamm, Robert

1985-01-01

Two types of advanced seals for liquid oxygen (LOX) turbopumps were investigated. One was a spiral-groove face seal whose function is to seal high-pressure LOX at the impeller end of the turbopump. The other was a floating-ring, Rayleigh-step, helium buffered seal used to prevent LOX ingress to the turbine side of the unit. For each seal type, two sizes were investigated (50 and 20 mm). A turbine-driven test rig was designed and manufactured, and a test program was completed on the 50 mm floating-ring, Rayleigh-step, helium buffered seal. Significant results were: vaporization in the flow path could cause failure by overheating; therefore, the spiral-groove pumping portion of the seal that provides the fluid film must circulate fluid without disruption if vaporization occurs in the sealing dam. This is successfully accomplished by a pressure-balanced spiral-groove concept that is described. The spiral-groove configuration is affected by turbulence in the fluid film and pressure drops due to fluid inertia at sudden contractions. The net results of these effects are deep grooves, large operating films, and high power loss when compared against seals operating with laminar films. Turbulence and inertia are induced by the high-density and low-viscosity characteristics of LOX. The program clearly pointed out the need to consider system environmental factors such as thermal and centrifugal distortions and rotor vibrations in the seal design.

Oxothiomolybdenum derivatives of the superlacunary crown heteropolyanion {P8W48}: structure of [K4{Mo4O4S4(H2O)3(OH)2}2(WO2)(P8W48O184)]30– and studies in solution.

PubMed

Korenev, Vladimir S; Floquet, Sébastien; Marrot, Jérôme; Haouas, Mohamed; Mbomekallé, Israël-Martyr; Taulelle, Francis; Sokolov, Maxim N; Fedin, Vladimir P; Cadot, Emmanuel

2012-02-20

Reaction of the cyclic lacunary [H(7)P(8)W(48)O(184)](33-) anion (noted P(8)W(48)) with the [Mo(2)S(2)O(2)(H(2)O)(6)](2+) oxothiocation led to two compounds, namely, [K(4){Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(WO(2))(P(8)W(48)O(184))](30-) (denoted 1) and [{Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(P(8)W(48)O(184))](36-) (denoted 2), which were characterized in the solid state and solution. In the solid state, the structure of [K(4){Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(WO(2))(P(8)W(48)O(184))](30-) reveals the presence of two disordered {Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2+) "handles" connected on both sides of the P(8)W(48) ring. Such a disorder is consistent with the presence of two geometrical isomers where the relative disposition of the two {Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2+) handles are arranged in a perpendicular or parallel mode. Such an interpretation is fully supported by (31)P and (183)W NMR solution studies. The relative stability of both geometrical isomers appears to be dependent upon the nature of the internal alkali cations, i.e., Na(+) vs K(+), and increased lability of the two {Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2+) handles, compared to the oxo analogous, was clearly identified by significant broadening of the (31)P and (183)W NMR lines. Solution studies carried out by UV-vis spectroscopy showed that formation of the adduct [{Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(P(8)W(48)O(184))](36-) occurs in the 1.5-4.7 pH range and corresponds to a fast and quantitative condensation process. Furthermore, (31)P NMR titrations in solution reveal formation of the "monohandle" derivative [{Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(P(8)W(48)O(184))](38-) as an intermediate prior to formation of the "bishandle" derivatives. Furthermore, the electrochemical behavior of [{Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(P(8)W(48)O(184))](36-) was studied in aqueous medium and compared with the parent anion P(8)W(48).

Compliant high temperature seals for dissimilar materials

DOEpatents

Rynders, Steven Walton; Minford, Eric; Tressler, Richard Ernest; Taylor, Dale M.

2001-01-01

A high temperature, gas-tight seal is formed by utilizing one or more compliant metallic toroidal ring sealing elements, where the applied pressure serves to activate the seal, thus improving the quality of the seal. The compliant nature of the sealing element compensates for differences in thermal expansion between the materials to be sealed, and is particularly useful in sealing a metallic member and a ceramic tube art elevated temperatures. The performance of the seal may be improved by coating the sealing element with a soft or flowable coating such as silver or gold and/or by backing the sealing element with a bed of fine powder. The material of the sealing element is chosen such that the element responds to stress elastically, even at elevated temperatures, permitting the seal to operate through multiple thermal cycles.

Nanoscale modulations in (KLa)(CaW)O{sub 6} and (NaLa)(CaW)O{sub 6}

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

Licurse, Mark W., E-mail: mlicurse@seas.upenn.edu; Borisevich, Albina Y., E-mail: albinab@ornl.gov; Davies, Peter K., E-mail: davies@seas.upenn.edu

2012-07-15

Complex nanoscale modulations are identified in two new A-site ordered perovskites, (KLa)(CaW)O{sub 6} and (NaLa)(CaW)O{sub 6}. In (KLa)(CaW)O{sub 6}, selected-area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM) show an incommensurate nanocheckerboard modulation with {approx}9.4 Multiplication-Sign 9.4a{sub p} periodicity (a{sub p} Almost-Equal-To 4 A for the cubic perovskite aristotype). For (NaLa)(CaW)O{sub 6} a one-dimensional modulation is observed with a {approx}16(1 1 0)a{sub p} repeat; the Left-Pointing-Angle-Bracket 1 1 0 Right-Pointing-Angle-Bracket orientation of the nanostripes is different from the Left-Pointing-Angle-Bracket 1 0 0 Right-Pointing-Angle-Bracket stripes observed in other mixed A-site systems. Studies using high temperature x-ray diffraction suggest the formationmore » of the complex modulations is associated with small deviations from the ideal 1:1:1:1 stoichiometry of the (A{sup +}La{sup 3+})(CaW)O{sub 6} phases. Z-contrast images acquired on an aberration-corrected microscope provide evidence for deviations from stoichiometry with a {approx}1:15 periodic arrangement of La{sub 4/3}(CaW)O{sub 6}:(NaLa)(CaW)O{sub 6} nano-phases. - Graphical abstract: Complex nanoscale modulations are identified in two new A-site ordered perovskites, (KLa)(CaW)O{sub 6} and (NaLa)(CaW)O{sub 6}. In (KLa)(CaW)O{sub 6}, selected-area electron diffraction and high-resolution transmission electron microscopy show a two-dimensional, nanocheckerboard modulation. For (NaLa)(CaW)O{sub 6} a one-dimensional modulation is observed; the Left-Pointing-Angle-Bracket 1 1 0 Right-Pointing-Angle-Bracket orientation of the nanostripes is different from the Left-Pointing-Angle-Bracket 1 0 0 Right-Pointing-Angle-Bracket stripes observed in other mixed A-site systems. Highlights: Black-Right-Pointing-Pointer Two new A-site ordered perovskites were synthesized, (KLa)(CaW)O{sub 6} and (NaLa)(CaW)O{sub 6}. Black

Detecting influences on California drought intervals using isotopes in tree-ring cellulose

NASA Astrophysics Data System (ADS)

Kanner, L. C.; Buenning, N. H.; Stott, L. D.; Stahle, D. W.

2012-12-01

Multi-decadal drought events have characterized climate variability in California over the last century. However, the causes of interannual precipitation variability and the origins of multi-decadal drought in California remain unclear. We utilize the oxygen isotopic composition (δ18O) of tree-ring cellulose in combination with previously developed ring-width measurements to trace the delivery of moisture to the region and investigate ocean-atmosphere patterns that might generate prolonged drought. Of the 36 Quercus douglasii (blue oak) sites in the California central valley, we have focused our work at two locations - one north of Los Angeles (34.74°N, 120°W, 1036 masl) and the other east of San Francisco (37.88°N 121.97°W, 182 masl). Using cores from at least five different trees at each location, tree-ring cellulose δ18O was measured for each year of growth from 1954 to 2004. The δ18O values of tree-ring cellulose range from 29‰ to 34‰ (VSMOW) at both sites and exhibit shared interannual variance (r = 0.43, p < 0.01). To trace changes in moisture delivery, we apply a biophysical model of cellulose δ18O and derive a proxy for rainfall δ18O. A reasonable approximation of rainfall δ18O is soil water δ18O, which, based on the biophysical model, can be estimated using cellulose δ18O, relative humidity, and temperature. High-resolution climate data from PRISM are combined with our cellulose measurements to compute soil water δ18O (and thus rainfall δ18O). Calculated rainfall δ18O is well correlated between the two locations (r = 0.55, p < 0.001) and the variance in δ18O at each site is 6‰. In terms of regional climate changes, our rainfall δ18O proxy exhibits a positive correlation with local precipitation amount, inferred from tree-ring width (r = 0.66, p < 0.001). This positive correlation suggests rainfall amount cannot be the main influence on the isotopic composition because changes in δ18O solely due to amount typically occur in the

An Experimental and Analytical Investigation of a Radial Face Seal

DTIC Science & Technology

1976-01-01

c \\]f’ n" •’ * TIMOTHY W. SWAFFORD h ; January 1976 Cjl...Vi 4J to c H Ö o Ö Ü (D M s Ö • H tfl 1-1 U a) :r^J. y^^^^^l 32 From NA iransparent tubing To seal ^xH— Globe valves Supply... c . 3 n) cNi a o cu <• C8 rH CC 1 A > o. U T-: 1 ^O J ^ ’ k 3 o a c ^ ^O TI —< r- -i! O 0) H - H rH H

Status of Understanding for Seal Materials

NASA Technical Reports Server (NTRS)

Brown, P. F.

1984-01-01

Material selection for mainshaft face and ring seals, labyrinth seals, accessory gearbox face seals, and lip seals are discussed in light of tribology requirements and a given seal application. Carbon graphite has been found to be one of the best sealing materials and it is widely used in current gas turbine mainshaft and accessory gearbox seals. Its popularity is due to its unique combination of properties which consists of dimensional stability, corrosion resistance, low friction, good self lubricating characteristics, high thermal conductivity and low thermal expansion, the latter two properties combining to provide good thermal shock resistance. A brief description of the seals and the requirements they must meet are discussed to provide insight into the limitations and advantages of the seals in containing the lubricant. A forecast is made of the operational requirements of main shaft and gearbox seals for advanced engines and candidate materials and coatings that may satisfy these advanced engine requirements.

Oil seal effects and subsynchronous vibrations in high-speed compressors

NASA Technical Reports Server (NTRS)

Allaire, P. E.; Kocur, J. A., Jr.

1985-01-01

Oil seals are commonly used in high speed multistage compressors. If the oil seal ring becomes locked up against the fixed portion of the seal, high oil film crosscoupled stiffnesses can result. A method of analysis for determining if the oil seals are locked up or not is discussed. The method is then applied to an oil seal in a compressor with subsynchronous vibration problems.

An Advanced Helium Buffer Seal for the SSME, ATD Oxygen Pump

NASA Technical Reports Server (NTRS)

Shapiro, Wilbur

2006-01-01

The present configuration of Helium Buffer Seal on the ATD oxygen pump consists of a pair of opposed carbon rings are forced axially against their containment housings. Leakage occurs through the clearance between the rings and the shaft. The total helium leakage through both sides is approximately 239 SCFM. A reduction in leakage to 50 SCFM will result in less helium storage and consequently permit a substantial increase in payload. Under Phase 1 NASA SBIR, a solid T-Ring seal was analyzed and designed that could satisfy the criteria of reducing leakage to 50 SCFM or less. The design makes maximum use of available length and employs a mid length row of hydrostatic orifaces that feed buffer helium directly into a 2 to 3 mil clearance region. The flow splits into opposite paths to buffer oxygen gas on one side and hydrogen gas on the turbine side. The seal employs opposed hydrostatic tapered land secondary seals that provide friction free support of the primary seal and allows the primary seal to follow rotor excursion and maintain concentric operating clearance . The predicted performance of the T-seal is excellent with operation at a safe film thickness of 2 to 2.5 mils and leakage less than 50 SCFM.

Tool For Installation Of Seal In Tube Fitting

NASA Technical Reports Server (NTRS)

Trevathan, Joseph R.

1993-01-01

Plierslike tool helps secure repair seal in fitting. Tool crimps repair seal into tube fitting, ensuring tight fit every time. Modified pair of snapring pliers to which knife-edge jaws have been added. Spring added between handles. Also includes separate, accompanying support ring.

STS-88 Crew Breakfast in O&C Building

NASA Technical Reports Server (NTRS)

1998-01-01

The STS-88 crew gather for the traditional pre-launch breakfast in the Operations and Checkout Building. From left to right are Mission Specialists Jerry L. Ross and Nancy J. Currie, Commander Robert D. Cabana, Pilot Frederick W. 'Rick' Sturckow, and Mission Specialists James H. Newman and Sergei Konstantinovich Krikalev, a Russian cosmonaut. Mission STS-88 is expected to launch at 3:56 a.m. EST aboard Space Shuttle Endeavour on Dec. 3. Endeavour carries the Unity connecting module, which the crew will be mating with the Russian-built Zarya control module already on orbit. In addition to Unity, two small replacement electronics boxes are on board for possible repairs to Zarya batteries. The mission is expected to last 11 days, 19 hours and 49 minutes, landing at 10:17 p.m. EST on Dec. 14.

Computer program documentation for the dynamic analysis of a noncontacting mechanical face seal

NASA Technical Reports Server (NTRS)

Auer, B. M.; Etsion, I.

1980-01-01

A computer program is presented which achieves a numerical solution for the equations of motion of a noncontacting mechanical face seal. The flexibly-mounted primary seal ring motion is expressed by a set of second order differential equations for three degrees of freedom. These equations are reduced to a set of first order equations and the GEAR software package is used to solve the set of first order equations. Program input includes seal design parameters and seal operating conditions. Output from the program includes velocities and displacements of the seal ring about the axis of an inertial reference system. One example problem is described.

Development of Advanced Seals for Industrial Turbine Applications

NASA Astrophysics Data System (ADS)

Chupp, Raymond E.; Aksit, Mahmut F.; Ghasripoor, Farshad; Turnquist, Norman A.; Dinc, Saim; Mortzheim, Jason; Demiroglu, Mehmet

2002-10-01

A critical area being addressed to improve industrial turbine performance is reducing the parasitic leakage flows through the various static and dynamic seals. Implementation of advanced seals into General Electric (GE) industrial turbines has progressed well over the last few years with significant operating performance gains achieved. Advanced static seals have been placed in gas turbine hot gas-path junctions and steam turbine packing ring segment end gaps. Brush seals have significantly decreased labyrinth seal leakages in gas turbine compressors and turbine interstages, steam turbine interstage and end packings, industrial compressor shaft seals, and generator seals. Abradable seals are being developed for blade-tip locations in various turbine locations. This presentation summarizes the status of advanced seal development for industrial turbines at GE.

Reliability Analysis of Sealing Structure of Electromechanical System Based on Kriging Model

NASA Astrophysics Data System (ADS)

Zhang, F.; Wang, Y. M.; Chen, R. W.; Deng, W. W.; Gao, Y.

2018-05-01

The sealing performance of aircraft electromechanical system has a great influence on flight safety, and the reliability of its typical seal structure is analyzed by researcher. In this paper, we regard reciprocating seal structure as a research object to study structural reliability. Having been based on the finite element numerical simulation method, the contact stress between the rubber sealing ring and the cylinder wall is calculated, and the relationship between the contact stress and the pressure of the hydraulic medium is built, and the friction force on different working conditions are compared. Through the co-simulation, the adaptive Kriging model obtained by EFF learning mechanism is used to describe the failure probability of the seal ring, so as to evaluate the reliability of the sealing structure. This article proposes a new idea of numerical evaluation for the reliability analysis of sealing structure, and also provides a theoretical basis for the optimal design of sealing structure.

Stabilizing geometry for hydrodynamic rotary seals

DOEpatents

Dietle, Lannie L.; Schroeder, John E.

2010-08-10

A hydrodynamic sealing assembly including a first component having first and second walls and a peripheral wall defining a seal groove, a second component having a rotatable surface relative to said first component, and a hydrodynamic seal comprising a seal body of generally ring-shaped configuration having a circumference. The seal body includes hydrodynamic and static sealing lips each having a cross-sectional area that substantially vary in time with each other about the circumference. In an uninstalled condition, the seal body has a length defined between first and second seal body ends which varies in time with the hydrodynamic sealing lip cross-sectional area. The first and second ends generally face the first and second walls, respectively. In the uninstalled condition, the first end is angulated relative to the first wall and the second end is angulated relative to the second wall. The seal body has a twist-limiting surface adjacent the static sealing lip. In the uninstalled condition, the twist-limiting surface is angulated relative to the peripheral wall and varies along the circumference. A seal body discontinuity and a first component discontinuity mate to prevent rotation of the seal body relative to the first component.

Experimental study on the sealing clearance between the labyrinth sealing displacer and cylinder in the 10 K G-M refrigerator

NASA Astrophysics Data System (ADS)

Hao, X. H.; Ju, Y. L.; Lu, Y. J.

2011-05-01

The labyrinth sealing displacer has been optimal designed to improve the operating stability and life-time of 10 K G-M refrigerator. The displacer was made of stainless steel 304 or inconel 718, coated with PTFE on its outer surface. Compared to the traditional piston-ring sealing displacer, the sealing clearance between the ridge of the labyrinth sealing displacer and cylinder is critical to the cooling performance of the G-M refrigerator. The displacers with different sealing clearances were experimentally studied, and the optimal clearance was given. The effects of the materials of the displacers and the system charge pressures on the performance of the labyrinth sealing were also tested and analyzed.

FY2017 status report: Model 9975 O-ring fixture long-term leak performance

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

Daugherty, W. L.

A series of experiments to monitor the aging performance of Viton® GLT and GLT-S O-rings used in the Model 9975 shipping package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperature. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups with GLT O-rings were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially andmore » have been tested periodically to determine if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, a smaller test matrix with fourteen additional tests was initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. Leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The 300 °F GLT O-ring fixtures failed after 2.8 to 5.7 years at temperature. The remaining GLT O-ring fixtures aging at 300 ºF were retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 9 to 10.5 years, or in GLT O-ring fixtures aging at 270 ºF for 5.7 years. These aging temperatures bound O-ring temperatures anticipated during normal storage in K-Area Complex (KAC). Leak test failures have been experienced in all of the GLT-S O-ring fixtures aging at 300 ºF and above. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 and 250 ºF for 6.9 to 7.5 years. Data from the O-ring fixtures are generally consistent with results from compression stress relaxation testing, and provide confidence in the predictive models based on those

Effects of Compression, Staging, and Braid Angle on Braided Rope Seal Performance

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Dunlap, Patrick H.; Adams, Michael L.

2006-01-01

This viewgraph presentation describes the effects of compression, staging and braid angle on braided rope seals. The contents include: 1) Test Fixture Schematics; 2) Comparison of Hybrid Seal Braid Architecture; 3) Residual Interference After Compression Cycling; 4) Effect of Compression, Braid, and Staging on Seal Flow; 5) Effect of Staging on Seal Pressure Drop; 6) Three Stag Seal Durability; 7) P&W Turbine Vane Seal Requirements; and 8) Next Generation Fighter F-22 P&W F119 Engines.

Seal for fluid forming tools

DOEpatents

Golovashchenko, Sergey Fedorovich [Beverly Hills, MI; Bonnen, John Joseph Francis [Milford, MI

2012-03-20

An electro-hydraulic forming tool for forming a sheet metal blank in a one-sided die has first and second rigid rings that engage opposite sides of a sheet metal blank. The rigid rings are contained within slots on a die portion and a hydraulic force applicator portion of the forming tool. The seals are either resiliently biased by an elastomeric member or inherently resiliently biased into contact with the blank.

An Overview of Advanced Elastomeric Seal Development and Testing Capabilities at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H.

2014-01-01

NASA is developing advanced space-rated elastomeric seals to support future space exploration missions to low Earth orbit, the Moon, near Earth asteroids, and other destinations. This includes seals for a new docking system and vehicle hatches. These seals must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air for extended missions. Seal compression loads must be below prescribed limits so as not to overload the mechanisms that compress them, and seal adhesion forces must be low to allow the sealed interface to be separated when required (e.g., during undocking or hatch opening). NASA Glenn Research Center has developed a number of unique test fixtures to measure the leak rates and compression and adhesion loads of candidate seal designs under simulated thermal, vacuum, and engagement conditions. Tests can be performed on full-scale seals with diameters on the order of 50 in., subscale seals that are about 12 in. in diameter, and smaller specimens such as O-rings. Test conditions include temperatures ranging from -238 to 662 F (-150 to 350 C), operational pressure gradients, and seal-on-seal or seal-on-flange mating configurations. Nominal and off-nominal conditions (e.g., incomplete seal compression) can also be simulated. This paper describes the main design features and capabilities of each type of test apparatus and provides an overview of advanced seal development activities at NASA Glenn.

Nitrile/Buna N Material Failure Assessment for an O-Ring used on the Gaseous Hydrogen Flow Control Valve (FCV) of the Space Shuttle Main Engine

NASA Technical Reports Server (NTRS)

Wingard, Doug

2006-01-01

After the rollout of Space Shuttle Discovery in April 2005 in preparation for return-to-flight, there was a failure of the Orbiter (OV-103) helium signature leak test in the gaseous hydrogen (GH2) system. Leakage was attributed to the Flow Control Valve (FCV) in Main Engine 3. The FCV determined to be the source of the leak for OV-103 is designated as LV-58. The nitrile/Buna N rubber O-ring seal was removed from LV-58, and failure analysis indicated radial cracks providing leak paths in one quadrant. Cracks were eventually found in 6 of 9 FCV O-rings among the three Shuttle Orbiters, though none were as severe as those for LV-58, OV-103. Testing by EM10 at MSFC on all 9 FCV O- rings included: laser dimensional, Shore A hardness and properties from a dynamic mechanical analyzer (DMA) and an Instron tensile machine. The following test data was obtained on the cracked quadrant of the LV-58, OV-103 O-ring: (1) the estimated compression set was only 9.5%, compared to none for the rest of the O-ring; (2) Shore A hardness for the O.D. was higher by almost 4 durometer points than for the rest of the O-ring; and (3) DMA data showed that the storage/elastic modulus E was almost 25% lower than for the rest of the O-ring. Of the 8 FCV O-rings tested on an Instron, 4 yielded tensile strengths that were below the MIL spec requirement of 1350 psi-a likely influence of rubber cracking. Comparisons were made between values of modulus determined by DNA (elastic) and Instron (Young s). Each nitrile/Buna N O-ring used in the FCV conforms to the MIL-P-25732C specification. A number of such O-rings taken from shelf storage at MSFC and Kennedy Space Center (KSC) were used to generate a reference curve of DMA glass transition temperature (Tg) vs. shelf storage time ranging from 8 to 26 years. A similar reference curve of TGA onset temperature (of rubber weight loss) vs. shelf storage time was also generated. The DMA and TGA data for the used FCV O-rings were compared to the reference

A Balanced-pressure Sliding Seal for Transfer of Pressurized Air Between Stationary and Rotating Parts

NASA Technical Reports Server (NTRS)

Curren, Arthur N; Cochran, Reeves P

1957-01-01

A combination sliding-ring and pressure-balancing seal capable of transferring pressurize air from stationary to rotating parts was developed and experimentally investigated at sliding velocities and cooling-air pressures up to 10,000 feet per minute and 38.3 pounds per square inch absolute, respectively. Leakage of cooling air was completely eliminated with an expenditure of balance air less than one-fourth the leakage loss of air from labyrinth seals under the same conditions. Additional cooling of the carbon-base seal rings was required, and the maximum wear rate on the rings was about 0.0005 inch per hour.

Performance of Oil Pumping Rings: An Analytical and Experimental Study

NASA Technical Reports Server (NTRS)

Eusepi, M. W.; Walowit, J. A.; Pinkus, O.; Holmes, P.

1986-01-01

A steady-state design computer program was developed to predict the performance of pumping rings as functions of geometry, applied loading, speed, ring modulus, and fluid viscosity. Additional analyses were developed to predict transient behavior of the ring and the effects of temperature rises occurring in the hydrodynamic film between the ring and shaft. The analysis was initially compared with previous experimental data and then used to design additional rings for further testing. Tests were performed with Rulon, carbon-graphite, and babbit rings. The design analysis was used to size all of the rings and to select the ranges of clearances, thickness, and loading. Although full quantitative agreement was lacking, relative agreement existed in that rings that were predicted to perform well theoretically, generally performed well experimentally. Some causes for discrepanices between theory and experiment are believed to be due to starvation, leakage past the secondary seal at high pressures, and uncertainties in the small clearances and local inlet temperatures to the pumping ring. A separate preliminary analysis was performed for a pumping Leningrader seal. This anlaysis can be used to predict the film thickness and flow rate thr ough the seal as a function of pressure, speed, loading, and geometry.

Sealing glasses for titanium and titanium alloys

DOEpatents

Brow, R.K.; McCollister, H.L.; Phifer, C.C.; Day, D.E.

1997-07-15

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B{sub 2}O{sub 3}), barium oxide (BaO), lanthanum oxide (La{sub 2}O{sub 3}), and at least one other oxide selected from the group consisting of aluminum oxide (Al{sub 2}O{sub 3}), calcium oxide (CaO), lithium oxide (Li{sub 2}O), sodium oxide (Na{sub 2}O), silicon dioxide (SiO{sub 2}), or titanium dioxide (TiO{sub 2}). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900 C, and generally about 700--800 C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps). 1 fig.

Sealing glasses for titanium and titanium alloys

DOEpatents

Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

1997-01-01

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B.sub.2 O.sub.3), barium oxide (BaO), lanthanum oxide (La.sub.2 O.sub.3), and at least one other oxide selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), calcium oxide (CaO), lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O), silicon dioxide (SiO.sub.2), or titanium dioxide (TiO.sub.2). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900.degree. C., and generally about 700.degree.-800.degree. C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

Sealing glasses for titanium and titanium alloys

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

Brow, R.K.; McCollister, H.L.; Phifer, C.C.

1997-07-15

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B{sub 2}O{sub 3}), barium oxide (BaO), lanthanum oxide (La{sub 2}O{sub 3}), and at least one other oxide selected from the group consisting of aluminum oxide (Al{sub 2}O{sub 3}), calcium oxide (CaO), lithium oxide (Li{sub 2}O), sodium oxide (Na{sub 2}O), silicon dioxide (SiO{sub 2}), or titanium dioxide (TiO{sub 2}). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansionmore » about that of titanium or titanium alloys, and with sealing temperatures less than about 900 C, and generally about 700--800 C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps). 1 fig.« less

Turbocharger with variable nozzle having vane sealing surfaces

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

Arnold, Philippe; Petitjean, Dominique; Ruquart, Anthony

2011-11-15

A variable nozzle for a turbocharger includes a plurality of vanes rotatably mounted on a nozzle ring and disposed in a nozzle flow path defined between the nozzle ring and an opposite nozzle wall. Either or both of the faces of the nozzle ring and nozzle wall include(s) at least one step that defines sealing surfaces positioned to be substantially abutted by airfoil surfaces of the vanes in the closed position of the vanes and to be spaced from the airfoil surfaces in positions other than the closed position. This substantial abutment between the airfoil surfaces and the sealing surfacesmore » serves to substantially prevent exhaust gas from leaking past the ends of the airfoil portions. At the same time, clearances between the nozzle ring face and the end faces of the airfoil portions can be sufficiently large to prevent binding of the vanes under all operating conditions.« less

Development of a high temperature ceramic-to-metal seal for Air Force Weapons Laboratory Laser

NASA Astrophysics Data System (ADS)

Honnell, R. E.; Stoddard, S. D.

1987-03-01

Procedures were developed for fabricating vacuum tight metal-to-ceramic ring seals between Inconel 625 and MgO-3 wt % Y2O3 tubes metallized with a calcia-alumina-silica glass (CaO-29 wt % Al2O3-35 wt % SiO2) containing 50 vol % molybdenum filler. Palniro No. 1 (Au-25 wt % Pd-25 wt % Ni) was found to be the most reliable braze for joining Inconel to metallized MgO-3 wt % Y2O3 bodies. The reliabilities of the processing procedures and the material systems were demonstrated. A prototype electrical feedthrough was fabricated for 1173 K operation in air or vacuum.

Oil encapsulation in core-shell alginate capsules by inverse gelation II: comparison between dripping techniques using W/O or O/W emulsions.

PubMed

Martins, Evandro; Poncelet, Denis; Rodrigues, Ramila Cristiane; Renard, Denis

2017-09-01

In the first part of this article, it was described an innovative method of oil encapsulation from dripping-inverse gelation using water-in-oil (W/O) emulsions. It was noticed that the method of oil encapsulation was quite different depending on the emulsion type (W/O or oil-in-water (O/W)) used and that the emulsion structure (W/O or O/W) had a high impact on the dripping technique and the capsules characteristics. The objective of this article was to elucidate the differences between the dripping techniques using both emulsions and compare the capsule properties (mechanical resistance and release of actives). The oil encapsulation using O/W emulsions was easier to perform and did not require the use of emulsion destabilisers. However, capsules produced from W/O emulsions were more resistant to compression and showed the slower release of actives over time. The findings detailed here widened the knowledge of the inverse gelation and gave opportunities to develop new techniques of oil encapsulation.

Brucella Antibodies in Alaskan True Seals and Eared Seals-Two Different Stories.

PubMed

Nymo, Ingebjørg H; Rødven, Rolf; Beckmen, Kimberlee; Larsen, Anett K; Tryland, Morten; Quakenbush, Lori; Godfroid, Jacques

2018-01-01

Brucella pinnipedialis was first isolated from true seals in 1994 and from eared seals in 2008. Although few pathological findings have been associated with infection in true seals, reproductive pathology including abortions, and the isolation of the zoonotic strain type 27 have been documented in eared seals. In this study, a Brucella enzyme-linked immunosorbent assay (ELISA) and the Rose Bengal test (RBT) were initially compared for 206 serum samples and a discrepancy between the tests was found. Following removal of lipids from the serum samples, ELISA results were unaltered while the agreement between the tests was improved, indicating that serum lipids affected the initial RBT outcome. For the remaining screening, we used ELISA to investigate the presence of Brucella antibodies in sera of 231 eared and 1,412 true seals from Alaskan waters sampled between 1975 and 2011. In eared seals, Brucella antibodies were found in two Steller sea lions ( Eumetopias jubatus ) (2%) and none of the 107 Northern fur seals ( Callorhinus ursinus ). The low seroprevalence in eared seals indicate a low level of exposure or lack of susceptibility to infection. Alternatively, mortality due to the Brucella infection may remove seropositive animals from the population. Brucella antibodies were detected in all true seal species investigated; harbor seals ( Phoca vitulina ) (25%), spotted seals ( Phoca largha ) (19%), ribbon seals ( Histriophoca fasciata ) (16%), and ringed seals ( Pusa hispida hispida ) (14%). There was a low seroprevalence among pups, a higher seroprevalence among juveniles, and a subsequent decreasing probability of seropositivity with age in harbor seals. Similar patterns were present for the other true seal species; however, solid conclusions could not be made due to sample size. This pattern is in accordance with previous reports on B. pinnipedialis infections in true seals and may suggest environmental exposure to B. pinnipedialis at the juvenile stage, with a

Compliant seal development

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.

1993-01-01

The compliant metallic seal combines the noncontact feature of the labyrinth seal, the low leakage of a mechanical seal, and the compliant nature of the brush seal. It consists of several thin metallic elements or leaves mounted within a ring which is press fit into the housing, and in form, sort of resembles a lip seal sections wiping the shaft. A second set of overlapping cover leaves are placed on top of the shaft riding leaves which reduces leakage and provides stiffness. The leaves can be straight or angle cut. The shaft riding fingers are designed with mismatched curvature to provide lift off similar to the Rayleigh lift pads in mechanical seals with leading edge clearances nearly twice those of the trailing edge as as shown by Fleming to be optimal for gas flows in convergent seal passages. Leading edge clearances range from 300 to 500 microinches. Balance pockets beneath the leaves provide fluid film feed to the 'Rayleigh lift' surface and the proper balance ratio (mechanical seal) when combined with the static pressure and film pressure. The leaves flex in the radial direction and accommodate thermomechanical behavior as well as axial motion and angular misalignment. In the static mode, there is a net closing force on the leaves. The seals were tested to 70 psi at speeds to 16,000 rpm or surface speeds to 330 fps and temperatures from ambient to 440 F. A slow cycle through the rig critical at 10,000 rpm induced a radial vibration response of 0.004 to 0.005 inch were accommodated by the seal. Preliminary performance data are encouraging demonstrating hydrodynamic liftoff and noncontacting operation at pressure and speeds typical of gas turbine engines. The leakage performance data are significantly better than commercial labyrinth and brush seals which should be expected as this design incorporates the features of the low leakage face or mechanical seal along with the flexibility of the brush configuration.

Compliant seal development

NASA Astrophysics Data System (ADS)

Hendricks, Robert C.

1993-10-01

The compliant metallic seal combines the noncontact feature of the labyrinth seal, the low leakage of a mechanical seal, and the compliant nature of the brush seal. It consists of several thin metallic elements or leaves mounted within a ring which is press fit into the housing, and in form, sort of resembles a lip seal sections wiping the shaft. A second set of overlapping cover leaves are placed on top of the shaft riding leaves which reduces leakage and provides stiffness. The leaves can be straight or angle cut. The shaft riding fingers are designed with mismatched curvature to provide lift off similar to the Rayleigh lift pads in mechanical seals with leading edge clearances nearly twice those of the trailing edge as as shown by Fleming to be optimal for gas flows in convergent seal passages. Leading edge clearances range from 300 to 500 microinches. Balance pockets beneath the leaves provide fluid film feed to the 'Rayleigh lift' surface and the proper balance ratio (mechanical seal) when combined with the static pressure and film pressure. The leaves flex in the radial direction and accommodate thermomechanical behavior as well as axial motion and angular misalignment. In the static mode, there is a net closing force on the leaves. The seals were tested to 70 psi at speeds to 16,000 rpm or surface speeds to 330 fps and temperatures from ambient to 440 F. A slow cycle through the rig critical at 10,000 rpm induced a radial vibration response of 0.004 to 0.005 inch were accommodated by the seal. Preliminary performance data are encouraging demonstrating hydrodynamic liftoff and noncontacting operation at pressure and speeds typical of gas turbine engines. The leakage performance data are significantly better than commercial labyrinth and brush seals which should be expected as this design incorporates the features of the low leakage face or mechanical seal along with the flexibility of the brush configuration.

An Overview of Advanced Elastomeric Seal Development and Testing Capabilities at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.

2014-01-01

NASA is developing advanced space-rated elastomeric seals to support future space exploration missions to low Earth orbit, the Moon, near Earth asteroids, and other destinations. This includes seals for a new docking system and vehicle hatches. These seals must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air for extended missions. Seal compression loads must be below prescribed limits so as not to overload the mechanisms that compress them, and seal adhesion forces must be low to allow the sealed interface to be separated when required (e.g., during undocking or hatch opening). NASA Glenn Research Center has developed a number of unique test fixtures to measure the leak rates and compression and adhesion loads of candidate seal designs under simulated thermal, vacuum, and engagement conditions. Tests can be performed on fullscale seals with diameters on the order of 50 in., subscale seals that are about 12 in. in diameter, and smaller specimens such as O-rings. Test conditions include temperatures ranging from -238 to 662degF (-150 to 350degC), operational pressure gradients, and seal-on-seal or seal-on-flange mating configurations. Nominal and off-nominal conditions (e.g., incomplete seal compression) can also be simulated. This paper describes the main design features and capabilities of each type of test apparatus and provides an overview of advanced seal development activities at NASA Glenn.

Dampers for Stationary Labyrinth Seals

NASA Technical Reports Server (NTRS)

El-Aini, Yehia; Mitchell, William; Roberts, Lawrence; Montgomery, Stuart; Davis, Gary

2011-01-01

Vibration dampers have been invented that are incorporated as components within the stationary labyrinth seal assembly. These dampers are intended to supplement other vibration-suppressing features of labyrinth seals in order to reduce the incidence of high-cycle-fatigue failures, which have been known to occur in the severe vibratory environments of jet engines and turbopumps in which labyrinth seals are typically used. A vibration damper of this type includes several leaf springs and/or a number of metallic particles (shot) all held in an annular seal cavity by a retaining ring. The leaf springs are made of a spring steel alloy chosen, in conjunction with design parameters, to maintain sufficient preload to ensure effectiveness of damping at desired operating temperatures. The cavity is vented via a small radial gap between the retaining ring and seal housing. The damping mechanism is complex. In the case of leaf springs, the mechanism is mainly friction in the slippage between the seal housing and individual dampers. In the case of a damper that contains shot, the damping mechanism includes contributions from friction between individual particles, friction between particles and cavity walls, and dissipation of kinetic energy of impact. The basic concept of particle/shot vibration dampers has been published previously; what is new here is the use of such dampers to suppress traveling-wave vibrations in labyrinth seals. Damping effectiveness depends on many parameters, including, but not limited to, coefficient of friction, mode shape, and frequency and amplitude of vibrational modes. In tests, preloads of the order of 6 to 15 lb (2.72 to 6.8 kilograms) per spring damper were demonstrated to provide adequate damping levels. Effectiveness of shot damping of vibrations having amplitudes from 20 to 200 times normal terrestrial gravitational acceleration (196 to 1,960 meters per square second) and frequencies up to 12 kHz was demonstrated for shot sizes from 0.032 to

36 CFR 223.88 - Bidding methods.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Bidding methods. 223.88... methods. (a) Competitive sales of National Forest timber shall be offered through either sealed or oral auction bidding. The method chosen for each sale will: (1) Insure open and fair competition, (2) Insure...

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.

Coaxial twin-shaft magnetic fluid seals applied in vacuum wafer-handling robot

NASA Astrophysics Data System (ADS)

Cong, Ming; Wen, Haiying; Du, Yu; Dai, Penglei

2012-07-01

Compared with traditional mechanical seals, magnetic fluid seals have unique characters of high airtightness, minimal friction torque requirements, pollution-free and long life-span, widely used in vacuum robots. With the rapid development of Integrate Circuit (IC), there is a stringent requirement for sealing wafer-handling robots when working in a vacuum environment. The parameters of magnetic fluid seals structure is very important in the vacuum robot design. This paper gives a magnetic fluid seal device for the robot. Firstly, the seal differential pressure formulas of magnetic fluid seal are deduced according to the theory of ferrohydrodynamics, which indicate that the magnetic field gradient in the sealing gap determines the seal capacity of magnetic fluid seal. Secondly, the magnetic analysis model of twin-shaft magnetic fluid seals structure is established. By analyzing the magnetic field distribution of dual magnetic fluid seal, the optimal value ranges of important parameters, including parameters of the permanent magnetic ring, the magnetic pole tooth, the outer shaft, the outer shaft sleeve and the axial relative position of two permanent magnetic rings, which affect the seal differential pressure, are obtained. A wafer-handling robot equipped with coaxial twin-shaft magnetic fluid rotary seals and bellows seal is devised and an optimized twin-shaft magnetic fluid seals experimental platform is built. Test result shows that when the speed of the two rotational shafts ranges from 0-500 r/min, the maximum burst pressure is about 0.24 MPa. Magnetic fluid rotary seals can provide satisfactory performance in the application of wafer-handling robot. The proposed coaxial twin-shaft magnetic fluid rotary seal provides the instruction to design high-speed vacuum robot.

Sealing Penetrating Eye Injuries with Photoactivated Bonding

DTIC Science & Technology

2012-09-01

light treatment parameters for sealing a variety of penetrating eye wounds and have demonstrated that these repair procedures are safe to ocular...AWARD NUMBER: W81XWH-09-2-0050 TITLE: Sealing Penetrating Eye Injuries with Photoactivated...TYPE Final 3. DATES COVERED (From - To) 1 Sep 2009-31 Aug 2012 4. TITLE AND SUBTITLE Sealing Penetrating Eye Injuries with Photoactivated Bonding

Note: O-ring stack system for electron gun alignment.

PubMed

Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

2015-01-01

We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.

SMA observations of the W3(OH) complex: Dynamical differentiation between W3(H2O) and W3(OH)

NASA Astrophysics Data System (ADS)

Qin, Sheng-Li; Schilke, Peter; Wu, Jingwen; Liu, Tie; Wu, Yuefang; Sánchez-Monge, Álvaro; Liu, Ying

2016-03-01

We present Submillimeter Array observations of the HCN (3-2) and HCO+ (3-2) molecular lines towards the W3(H2O) and W3(OH) star-forming complexes. Infall and outflow motions in the W3(H2O) have been characterized by observing HCN and HCO+ transitions. High-velocity blue/red-shifted emission, tracing the outflow, show multiple knots, which might originate in episodic and precessing outflows. `Blue-peaked' line profiles indicate that gas is infalling on to the W3(H2O) dust core. The measured large mass accretion rate, 2.3 × 10-3 M⊙ yr-1, together with the small free-fall time-scale, 5 × 103 yr, suggest W3(H2O) is in an early evolutionary stage of the process of formation of high-mass stars. For the W3(OH), a two-layer model fit to the HCN and HCO+ spectral lines and Spizter/Infrared Array Camera (IRAC) images support that the W3(OH) H II region is expanding and interacting with the ambient gas, with the shocked neutral gas being expanding with an expansion time-scale of 6.4 × 103 yr. The observations suggest different kinematical time-scales and dynamical states for the W3(H2O) and W3(OH).

Carbon sources and trophic relationships of ice seals during recent environmental shifts in the Bering Sea.

PubMed

Wang, Shiway W; Springer, Alan M; Budge, Suzanne M; Horstmann, Lara; Quakenbush, Lori T; Wooller, Matthew J

2016-04-01

Dramatic multiyear fluctuations in water temperature and seasonal sea ice extent and duration across the Bering-Chukchi continental shelf have occurred in this century, raising a pressing ecological question: Do such environmental changes alter marine production processes linking primary producers to upper trophic-level predators? We examined this question by comparing the blubber fatty acid (FA) composition and stable carbon isotope ratios of individual FA (δ¹³CFA) of adult ringed seals (Pusa hispida), bearded seals (Erignathus barbatus), spotted seals (Phoca largha), and ribbon seals (Histriophoca fasciata), collectively known as "ice seals," sampled during an anomalously warm, low sea ice period in 2002-2005 in the Bering Sea and a subsequent cold, high sea ice period in 2007-2010. δ¹³C(FA) values, used to estimate the contribution to seals of carbon derived from sea ice algae (sympagic production) relative to that derived from water column phytoplankton (pelagic production), indicated that during the cold period, sympagic production accounted for 62-80% of the FA in the blubber of bearded seals, 51-62% in spotted seals, and 21-60% in ringed seals. Moreover, the δ¹³CFA values of bearded seals indicated a greater incorporation of sympagic FAs during the cold period than the warm period. This result provides the first empirical evidence of an ecosystem-scale effect of a putative change in sympagic production in the Western Arctic. The FA composition of ice seals showed clear evidence of resource partitioning among ringed, bearded, and spotted seals, and little niche separation between spotted and ribbon seals, which is consistent with previous studies. Despite interannual variability, the FA composition of ringed and bearded seals showed little evidence of differences in diet between the warm and cold periods. The findings that sympagic production contributes significantly to food webs supporting ice seals, and that the contribution apparently is less in

EG and G and NASA face seal codes comparison

NASA Technical Reports Server (NTRS)

Basu, Prit

1994-01-01

This viewgraph presentation presents the following results for the example comparison: EG&G code with face deformations suppressed and SPIRALG agree well with each other as well as with the experimental data; 0 rpm stiffness data calculated by EG&G code are about 70-100 percent lower than that by SPIRALG; there is no appreciable difference between 0 rpm and 16,000 rpm stiffness and damping coefficients calculated by SPIRALG; and the film damping above 500 psig calculated by SPIRALG is much higher than the O-Ring secondary seal damping (e.g. 50 lbf.s/in).

Note: O-ring stack system for electron gun alignment

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

Park, In-Yong; Cho, Boklae; Han, Cheolsu

We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignmentmore » and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.« less

Comparing Sources of Storm-Time Ring Current O+

NASA Astrophysics Data System (ADS)

Kistler, L. M.

2015-12-01

The first observations of the storm-time ring current composition using AMPTE/CCE data showed that the O+ contribution to the ring current increases significantly during storms. The ring current is predominantly formed from inward transport of the near-earth plasma sheet. Thus the increase of O+ in the ring current implies that the ionospheric contribution to the plasma sheet has increased. The ionospheric plasma that reaches the plasma sheet can come from both the cusp and the nightside aurora. The cusp outflow moves through the lobe and enters the plasma sheet through reconnection at the near-earth neutral line. The nightside auroral outflow has direct access to nightside plasma sheet. Using data from Cluster and the Van Allen Probes spacecraft, we compare the development of storms in cases where there is a clear input of nightside auroral outflow, and in cases where there is a significant cusp input. We find that the cusp input, which enters the tail at ~15-20 Re becomes isotropized when it crosses the neutral sheet, and becomes part of the hot (>1 keV) plasma sheet population as it convects inward. The auroral outflow, which enters the plasma sheet closer to the earth, where the radius of curvature of the field line is larger, does not isotropize or become significantly energized, but remains a predominantly field aligned low energy population in the inner magnetosphere. It is the hot plasma sheet population that gets accelerated to high enough energies in the inner magnetosphere to contribute strongly to the ring current pressure. Thus it appears that O+ that enters the plasma sheet further down the tail has a greater impact on the storm-time ring current than ions that enter closer to the earth.

NINTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

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

Daugherty, W.

2014-08-06

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperatures. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determinemore » if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. High temperature aging continues for 23 GLT O-ring fixtures at 200 – 270 ºF. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The earliest 300 °F GLT O-ring fixture failure was observed at 34 months. The remaining GLT O-ring fixtures aging at 300 ºF have been retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 72 - 96 months, which bounds O-ring temperatures anticipated during storage in K-Area Complex (KAC). Based on expectations that the 200 ºF fixtures will remain leak-tight for a significant period yet to come, 2 additional fixtures began aging in 2011 at 270 ºF, with hopes that they may reach a failure condition before the 200 ºF fixtures, thus providing additional time to failure data. High temperature aging continues for 6 GLT-S O-ring fixtures at 200 – 300 ºF. Room temperature leak test failures have been experienced in all 8

A Sample Return Container with Hermetic Seal

NASA Technical Reports Server (NTRS)

Kong, Kin Yuen; Rafeek, Shaheed; Sadick, Shazad; Porter, Christopher C.

2000-01-01

A sample return container is being developed by Honeybee Robotics to receive samples from a derivative of the Champollion/ST4 Sample Acquisition and Transfer Mechanism or other samplers and then hermetically seal samples for a sample return mission. The container is enclosed in a phase change material (PCM) chamber to prevent phase change during return and re-entry to earth. This container is designed to operate passively with no motors and actuators. Using the sampler's featured drill tip for interfacing, transfer-ring and sealing samples, the container consumes no electrical power and therefore minimizes sample temperature change. The circular container houses a few isolated canisters, which will be sealed individually for samples acquired from different sites or depths. The drill based sampler indexes each canister to the sample transfer position, below the index interface for sample transfer. After sample transfer is completed, the sampler indexes a seal carrier, which lines up seals with the openings of the canisters. The sampler moves to the sealing interface and seals the sample canisters one by one. The sealing interface can be designed to work with C-seals, knife edge seals and cup seals. Again, the sampler provides all sealing actuation. This sample return container and co-engineered sample acquisition system are being developed by Honeybee Robotics in collaboration with the JPL Exploration Technology program.

Elastomeric Seal Performance after Terrestrial Ultraviolet Radiation Exposure

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.; Dunlap, Patrick H.

2015-01-01

Ultraviolet radiation was evaluated to determine its negative effects on the performance of elastomeric gas pressure seals. The leak rates of the silicone elastomer S0383-70 O-ring test articles were used to quantify the degradation of the seals after exposure to vacuum-ultraviolet and/or middle-to-near-ultraviolet wavelength radiation. Three groups of seals were exposed in terrestrial facilities to 115-165 nm wavelength radiation, 230-500 nm wavelength radiation, or both spectrums, for an orbital spaceflight equivalent of 125 hours. The leak rates of the silicone elastomer S0383-70 seals were quantified and compared to samples that received no radiation. Each lot contained six samples and statistical t-tests were used to determine the separate and combined influences of exposure to the two wavelength ranges. A comparison of the mean leak rates of samples exposed to 115-165 nm wavelength radiation to the control specimens showed no difference, suggesting that spectrum was not damaging. The 230-500 nm wavelength appeared to be damaging, as the mean leak rates of the specimens exposed to that range of wavelengths, and those exposed to the combined 115-165 nm and 230-500 nm spectrums, were significantly different from the leak rates of the control specimens. Most importantly, the test articles exposed to both wavelength spectrums exhibited mean leak rates two orders of magnitude larger than any other exposed specimens, which suggested that both wavelength spectrums are important when simulating the orbital environment.

SEVENTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

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

Daugherty, W.

2012-08-30

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. Seventy tests using mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determine if they meet the criterion of leak-tightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. High temperature aging continues for 23more » GLT O-ring fixtures at 200 – 270 ºF. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The remaining GLT O-ring fixtures aging at 300 ºF have been retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 54-72 months, which is still bounding to O-ring temperatures during storage in K-Area Complex (KAC). Based on expectations that the fixtures aging at 200 ºF will remain leak-tight for a significant period yet to come, 2 additional fixtures began aging in 2011 at an intermediate temperature of 270 ºF, with hopes that they may reach a failure condition before the 200 ºF fixtures. High temperature aging continues for 6 GLT-S O-ring fixtures at 200 – 300 ºF. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 ºF. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 - 300 ºF for 30 - 36 months. For O-ring fixtures that have failed the room temperature leak test and been disassembled, the O-rings displayed a compression set ranging from 51 – 96%. This is greater than seen to date for any packages inspected during

Cellulose nanofibrils for one-step stabilization of multiple emulsions (W/O/W) based on soybean oil.

PubMed

Carrillo, Carlos A; Nypelö, Tiina E; Rojas, Orlando J

2015-05-01

Cellulose nanofibrils (CNF) were incorporated in water-in-oil (W/O) microemulsions and emulsions, as well as water-in-oil-in-water (W/O/W) multiple emulsions using soybean oil. The addition of CNF to the aqueous phase expanded the composition range to obtain W/O/W emulsions. CNF also increased the viscosity of the continuous phase and reduced the drop size both of which increased the stability and effective viscosity of the emulsions. The effects of oil type and polarity on the properties of the W/O/W emulsions were tested with limonene and octane, which compared to soybean oil produced a smaller emulsion drop size, and thus a higher emulsion viscosity. Overall, CNF are a feasible alternative to conventional polysaccharides as stability enhancers for normal and multiple emulsions that exhibit strong shear thinning behavior. Copyright © 2014 Elsevier Inc. All rights reserved.

SMA OBSERVATIONS OF THE W3(OH) COMPLEX: PHYSICAL AND CHEMICAL DIFFERENTIATION BETWEEN W3(H{sub 2}O) AND W3(OH)

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

Qin, Sheng-Li; Schilke, Peter; Sánchez-Monge, Álvaro

2015-04-10

We report on the Submillimeter Array (SMA) observations of molecular lines at 270 GHz toward the W3(OH) and W3(H{sub 2}O) complex. Although previous observations already resolved the W3(H{sub 2}O) into two or three sub-components, the physical and chemical properties of the two sources are not well constrained. Our SMA observations clearly resolved the W3(OH) and W3(H{sub 2}O) continuum cores. Taking advantage of the line fitting tool XCLASS, we identified and modeled a rich molecular spectrum in this complex, including multiple CH{sub 3}CN and CH{sub 3}OH transitions in both cores. HDO, C{sub 2}H{sub 5}CN, O{sup 13}CS, and vibrationally excited lines ofmore » HCN, CH{sub 3}CN, and CH{sub 3}OCHO were only detected in W3(H{sub 2}O). We calculate gas temperatures and column densities for both cores. The results show that W3(H{sub 2}O) has higher gas temperatures and larger column densities than W3(OH) as previously observed, suggesting physical and chemical differences between the two cores. We compare the molecular abundances in W3(H{sub 2}O) to those in the Sgr B2(N) hot core, the Orion KL hot core, and the Orion Compact Ridge, and discuss the chemical origin of specific species. An east–west velocity gradient is seen in W3(H{sub 2}O), and the extension is consistent with the bipolar outflow orientation traced by water masers and radio jets. A north–south velocity gradient across W3(OH) is also observed. However, with current observations we cannot be assured whether the velocity gradients are caused by rotation, outflow, or radial velocity differences of the sub-components of W3(OH)« less

Performance of Subscale Docking Seals Under Simulated Temperature Conditions

NASA Technical Reports Server (NTRS)

Smith, Ian M.; Daniels, Christopher C.

2008-01-01

A universal docking system is being developed by the National Aeronautics and Space Administration (NASA) to support future space exploration missions to low Earth orbit (LEO), to the moon, and to Mars. The candidate docking seals for the system are a composite design consisting of elastomer seal bulbs molded into the front and rear sides of a metal ring. The test specimens were subscale seals with two different elastomer cross-sections and a 12-in. outside diameter. The seal assemblies were mated in elastomer seal-on-metal plate and elastomer seal-on-elastomer seal configurations. The seals were manufactured from S0383-70 silicone elastomer compound. Nominal and off-nominal joint configurations were examined. Both the compression load required to mate the seals and the leak rate observed were recorded while the assemblies were subjected to representative docking system operating temperatures of -58, 73, and 122 F (-50, 23, and 50 C). Both the loads required to fully compress the seals and their leak rates were directly proportional to the test temperature.

The effects of biomacromolecules on the physical stability of W/O/W emulsions.

PubMed

Li, Jinlong; Zhu, Yunping; Teng, Chao; Xiong, Ke; Yang, Ran; Li, Xiuting

2017-02-01

The effect of bovine serum albumin (BSA), whey protein isolate (WPI), whey protein hydrolysate (WPH), sodium caseinate (SC), carboxymethylcellulose sodium (CMC), fish gelatin (FG), high methoxyl apple pectin (HMAP), low methoxyl apple pectin (LMAP), gum Arabic (GA), ι-carrageenan (CGN), and hydroxypropyl chitosan (HPCTS) on physical stability of internal or external aqueous phase of water-in-oil-in-water (W/O/W) emulsions was evaluated. WPI and CGN in the internal aqueous phase, and GA, HPCTS, and CMC in the external phase reduced the size of emulsion droplets. BSA, WPI, SC, FG, CGN, and HPCTS improved the dilution stability of W/O/W emulsions, but HMAP had a negative effect. BSA, WPI, SC, FG, LMAP, GA, CGN, HPCTS, or CMC significantly improved the thermal stability of W/O/W emulsions. Results also indicated that the addition of CGN (1.0%), HMAP (1.0%), WPH (1.0%), or HPCTS (1.0%) in internal aqueous phase significantly increased the viscosity of emulsions, however, addition to the external aqueous phase had insignificant effects. A protein-knockout experiment confirmed that proteins as biomacromolecules, were the key factor in improving physical stability of emulsions.

The Influence of Hoop Diameter on Aerodynamic Performance of O-Ring Paper Plane

NASA Astrophysics Data System (ADS)

Ismail, N. I.; Sharudin, Hazim; Talib, R. J.; Hassan, A. A.; Yusoff, H.

2018-05-01

The O-ring paper plane can be categorized as one of the Micro Air Vehicle (MAV) based on their characteristics and size. However, the aerodynamics performance of the O-ring paper plane was not fully discovered by previous researchers due to its aerodynamics complexity and various hoop diameters. Thus, the objective of this research is to study the influence of hoop diameters towards the aerodynamics performance of O-ring paper plane. In this works, three types of O-ring paper plane known as Design 1, 2 and 3 with different hoop diameter were initially developed by using the ANSYS-Design Modeler. All the design was analyzed based on aerodynamic simulations works executed on ANSYS-CFX solver. The results suggested that Design 3 (with larger hoop size) produced better CL, CLmax and AoAstall magnitude compared to other design. In fact, O-ring paper plane with larger hoop size configurations showed potential in providing at least 5.2% and 5.9% better performance in stability (ΔCM/ΔCL) and aerodynamic efficiency (CL/CDmax), respectively. Despite the advantages found in lift performances, however, O-ring paper plane with larger hoop size configurations slightly suffered from larger drag increment (CDincrement) compared to smaller hoop size configurations. Based on these results, it can be presumed that O-Ring paper plane with larger hoop sizes contributed into better lift, stability and aerodynamic efficiency performances but slightly suffered from larger drag penalty.

Electronic structure of BaO/W cathode surfaces

NASA Technical Reports Server (NTRS)

Muller, Wolfgang

1989-01-01

The local electronic structure of the emissive layer of barium dispenser thermionic cathodes is investigated theoretically using the relativistic scattered-wave approach. The interaction of Ba and O with W, Os, and W-Os alloy surfaces is studied with atomic clusters modeling different absorption environments representative of B- and M-type cathodes. Ba is found to be strongly oxidized, while O and the metal substrate are in a reduced chemical state. The presence of O enhances the surface dipole and Ba binding energy relative to Ba on W. Model results for W-Os alloy substrates show only relatively small changes in Ba and O for identical geometries, but very large charge redistributions inside the substrate, which are attributed to the electronegativity difference between Os and W. If Os is present in the surface layer, the charge transfer from Ba to the substrate and the Ba binding energy increase relative to W. Explanations are offered for the improved electron emission from alloy surfaces and the different emission enhancement for different alloy substrates.

The source of O+ in the storm time ring current

NASA Astrophysics Data System (ADS)

Kistler, L. M.; Mouikis, C. G.; Spence, H. E.; Menz, A. M.; Skoug, R. M.; Funsten, H. O.; Larsen, B. A.; Mitchell, D. G.; Gkioulidou, M.; Wygant, J. R.; Lanzerotti, L. J.

2016-06-01

A stretched and compressed geomagnetic field occurred during the main phase of a geomagnetic storm on 1 June 2013. During the storm the Van Allen Probes spacecraft made measurements of the plasma sheet boundary layer and observed large fluxes of O+ ions streaming up the field line from the nightside auroral region. Prior to the storm main phase there was an increase in the hot (>1 keV) and more isotropic O+ ions in the plasma sheet. In the spacecraft inbound pass through the ring current region during the storm main phase, the H+ and O+ ions were significantly enhanced. We show that this enhanced inner magnetosphere ring current population is due to the inward adiabatic convection of the plasma sheet ion population. The energy range of the O+ ion plasma sheet that impacts the ring current most is found to be from ~5 to 60 keV. This is in the energy range of the hot population that increased prior to the start of the storm main phase, and the ion fluxes in this energy range only increase slightly during the extended outflow time interval. Thus, the auroral outflow does not have a significant impact on the ring current during the main phase. The auroral outflow is transported to the inner magnetosphere but does not reach high enough energies to affect the energy density. We conclude that the more energetic O+ that entered the plasma sheet prior to the main phase and that dominates the ring current is likely from the cusp.

Magnetodielectric effect in (1 - x)(Ba0.88Ca0.12)(Ti0.88Zr0.12)O3 - xCoFe2O4

NASA Astrophysics Data System (ADS)

Pan, Pengfei; Tao, Jin; Ma, Fusheng; Zhang, Ning

2018-05-01

Magnetodielectric (MD) materials have attracted considerable attention due to their intriguing physics and potential future applications. In this work, polycrystalline (1 - x)(Ba0.88Ca0.12)(Ti0.88Zr0.12)O3 - xCoFe2O4 (x = 0.10, 0.20, 0.30, 0.40) ceramic have been prepared via sol-gel method. The room temperature magnetic and ferroelectric behaviors of the synthesized composites were investigated. For the composite with x = 0.40, a MD ratio of 5.37% was achieved under a magnetic field of 1.5 T at f = 1 kHz. The measured "butterfly hysteresis" MD curves exhibit an obvious dielectric anomaly. Theoretical analysis suggests that the observed magnetodielectric effect is attributed to the magnetoresistance effect and magnetoelectric coupling.

Self-Sealing Wet Chemistry Cell for Field Analysis

NASA Technical Reports Server (NTRS)

Beegle, Luther W.; Soto, Juancarlos; Lasnik, James; Roark, Shane

2012-01-01

In most analytical investigations, there is a need to process complex field samples for the unique detection of analytes, especially when detecting low concentration organic molecules that may identify extraterrestrial life. Wet chemistry based instruments are the techniques of choice for most laboratory- based analysis of organic molecules due to several factors including less fragmentation of fragile biomarkers, and ability to concentrate target species resulting in much lower limits of detection. Development of an automated wet chemistry preparation system that can operate autonomously on Earth and is also designed to operate under Martian ambient conditions will demonstrate the technical feasibility of including wet chemistry on future missions. An Automated Sample Processing System (ASPS) has recently been developed that receives fines, extracts organics through solvent extraction, processes the extract by removing non-organic soluble species, and delivers sample to multiple instruments for analysis (including for non-organic soluble species). The key to this system is a sample cell that can autonomously function under field conditions. As a result, a self-sealing sample cell was developed that can autonomously hermetically seal fines and powder into a container, regardless of orientation of the apparatus. The cap is designed with a beveled edge, which allows the cap to be self-righted as the capping motor engages. Each cap consists of a C-clip lock ring below a crucible O-ring that is placed into a groove cut into the sample cap.

Effect of Nb2O5 doping on improving the thermo-mechanical stability of sealing interfaces for solid oxide fuel cells.

PubMed

Zhang, Qi; Du, Xinhang; Tan, Shengwei; Tang, Dian; Chen, Kongfa; Zhang, Teng

2017-07-13

Nb 2 O 5 is added to a borosilicate sealing system to improve the thermo-mechanical stability of the sealing interface between the glass and Fe-Cr metallic interconnect (Crofer 22APU) in solid oxide fuel cells (SOFCs). The thermo-mechanical stability of the glass/metal interface is evaluated experimentally as well as by using a finite element analysis (FEA) method. The sealing glass doped with 4 mol.% Nb 2 O 5 shows the best thermo-mechanical stability, and the sealing couple of Crofer 22APU/glass/GDC (Gd 0.2 Ce 0.8 O 1.9 ) remains intact after 50 thermal cycles. In addition, all sealing couples show good joining after being held at 750 °C for 1000 h. Moreover, the possible mechanism on the thermo-mechanical stability of sealing interface is investigated in terms of stress-based and energy-based perspectives.

Bidirectional Brush Seals

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Wilson, Jack; Wu, Tom; Flower, Ralph

1997-01-01

Presented is a study of the use of a set of I.D./O.D. bidirectional press seals to reduce the leakage losses in a wave rotor. Relative to the baseline configuration, data indicate the use of brush seals enhanced wave rotor efficiency from 36 to 45 percent at low leakages (small rotor endwall gap spacings) and from 15 to 33 percent at high leakages (larger endwall gap spacings). These brush seals are capable of sealing positive or negative pressure drops with respect to the axial direction. Surface tribology for these tests suggested little evidence of grooving although the bristles appeared polished.

Incorporation of water-in-oil-in-water (W1/O/W2) double emulsion in a set-type yogurt model.

PubMed

Lalou, Sofia; Kadri, Hani El; Gkatzionis, Konstantinos

2017-10-01

The effect of W 1 /O/W 2 emulsion incorporation in set-type yogurt on the acidification process, physicochemical properties, bacterial growth kinetics and structural characteristics was investigated. The W 1 /O/W 2 emulsion was formed by using a two-step homogenisation process and milk as the W 1 and W 2 phases, and stability was monitored with optical microscopy and cryo-SEM. Adding the W 1 /O/W 2 emulsions reduced the acidification rate, viscosity and water retention capacity. Texture (adhesiveness, cohesiveness, hardness, and gumminess) differed in yogurts containing W 1 /O/W 2 emulsion compared to controls during the acidification process, however, trends became stable during storage. The growth of S. thermophilus during the acidification process of yogurt was reduced in the presence of W 1 /O/W 2 emulsion while L. bulgaricus trended higher during storage. This study shows that yogurts containing W 1 /O/W 2 emulsion are feasible subject to processing modification. Copyright © 2017 Elsevier Ltd. All rights reserved.

A 1kW EUV source for lithography based on FEL emission in a compact storage ring

NASA Astrophysics Data System (ADS)

Feser, Michael; Ruth, Ron; Loewen, Rod

2017-10-01

EUV has long been hailed as the next generation lithography technology. Its adoption into high volume manufacturing (HVM), however, has been delayed several technology nodes due to technical issues, many of which can be attributed to the EUV source performance. Today's EUV lithography scanners are powered by laser produce plasma (LPP) sources. They have issues with power scaling beyond 300 W, reliability and contamination. Free Electron Lasers (FELs) have been considered as an alternative EUV source. Advantages of accelerator based sources are the maturity of the accelerator technology, lack of debris/contamination, and ability to provide high power. Industry turned away from this technology because of the requirement to feed up to 10 scanners from one linear FEL to make it economically feasible, the large footprint, and generation of radioactive byproducts. All of these issues are overcome in the presented concept using a compact storage ring with steady-state FEL lasing action. At 1 kW output power, comparable cost and footprint to an LPP source, this source is ideally suited for use on a single scanner and promises reliable, contamination free operation. FEL action in the storage ring is sustained by operating the FEL well below the saturation regime and preserving the equilibrium low emittance and energy distribution of the ring.

Overview of LIDS Docking and Berthing System Seals

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Dunlap, Patrick H., Jr.; deGroh, Henry C., III; Steinetz, Bruce M.; Oswald, Jay J.; Smith, Ian

2007-01-01

This viewgraph presentation describes the Low Impact Docking System (LIDS) docking and berthing system seals. The contents include: 1) Description of the Application: Low Impact Docking System (LIDS); 2) LIDS Seal Locations: Vehicle Undocked (Hatch Closed); 3) LIDS Seal Locations: Mechanical Pass Thru; 4) LIDS Seal Locations: Electrical and Pyro Connectors; 5) LIDS Seal Locations: Vehicle Docked (Hatches Open); 6) LIDS Seal Locations: Main Interface Seal; 7) Main Interface Seal Challenges and Specifications; 8) Approach; 9) Seal Concepts Under Development/Evaluation; 10) Elastomer Material Evaluations; 11) Evaluation of Relevant Seal Properties; 12) Medium-Scale (12") Gask-O-Seal Compression Tests; 13) Medium-Scale Compression Results; 14) Adhesion Forces of Elliptical Top Gask-o-seals; 15) Medium-Scale Seals; 16) Medium-Scale Leakage Results: Effect of Configuration; 17) Full Scale LIDS Seal Test Rig Development; 18) Materials International Space Station Experiment (MISSE 6A and 6B); and 19) Schedule.

Effects of Low Earth Orbit on Docking Seal Materials

NASA Technical Reports Server (NTRS)

Imka, Emily C.; Asmar, Olivia C.; deGroh, Henry C., III; Banks, Bruce A.

2014-01-01

Spacecraft docking seals are typically made of silicone elastomers. When such seals are exposed to low Earth orbit (LEO) conditions, they can suffer damage from ultraviolet (UV) radiation and atomic oxygen (AO, or monoatomic oxygen, the predominant oxygen species in LEO). An experiment flew on the International Space Station (ISS) to measure the effects of LEO on seal materials S0383-70 and ELA-SA-401 and various mating counterface materials which included anodized aluminum. Samples flown in different orientations received different amounts of UV and AO. The hypotheses were that most of the damage would be from UV, and 10 days or more of exposure in LEO would badly damage the seals. Eighteen seals were exposed for 543 days in ram (windward), zenith (away from Earth), or wake (leeward) orientations, and 15 control samples (not flown) provided undamaged baseline leakage. To determine post-flight leak rates, each of the 33 seals were placed in an O-ring groove of a leak test fixture and pressure tested over time. Resistance temperature detectors (RTDs), pressure transducers, and LabVIEW (National Instruments) programs were used to measure and analyze the temperature and pressure and calculate leakage. Average leakage of control samples was 2.6 x 10(exp -7) lbs/day. LEO exposure did not considerably damage ELA-SA-401. The S0383-70 flight samples leaked at least 10 times more than ELA-SA-401 in all cases except one, demonstrating that ELA-SA-401 may be a more suitable sealing material in LEO. AO caused greater damage than UV; samples in ram orientation (receiving an AO fluence of 4.3 x 10(exp 21) atoms/(sq cm) and in wake (2.9x 10(exp 20) atoms/(sq cm)) leaked more than those in zenith orientation (1.58 x 10(exp 20) atoms/(sq cm)), whereas variations in UV exposure did not seem to affect the samples. Exposure to LEO did less damage to the seals than hypothesized, and the data did not support the conjecture that UV causes more damage than AO.

Biocompatible Stimuli-Responsive W/O/W Multiple Emulsions Prepared by One-Step Mixing with a Single Diblock Copolymer Emulsifier.

PubMed

Protat, Marine; Bodin, Noémie; Gobeaux, Frédéric; Malloggi, Florent; Daillant, Jean; Pantoustier, Nadège; Guenoun, Patrick; Perrin, Patrick

2016-09-22

Multiple water-in-oil-in-water (W/O/W) emulsions are promising materials in designing carriers of hydrophilic molecules or drug delivery systems, provided stability issues are solved and biocompatible chemicals can be used. In this work, we designed a biocompatible amphiphilic copolymer, poly(dimethylsiloxane)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMS-b-PDMAEMA), that can stabilize emulsions made with various biocompatible oils. The hydrophilic/hydrophobic properties of the copolymer can be adjusted using both pH and ionic strength stimuli. Consequently, the making of O/W (oil in water), W/O (water in oil), and W/O/W emulsions can be achieved by sweeping the pH and ionic strength. Of importance, W/O/W emulsions are formulated over a large pH and ionic strength domain in a one-step emulsification process via transitional phase inversion and are stable for several months. Cryo-TEM and interfacial tension studies show that the formation of these W/O/W emulsions is likely to be correlated to the interfacial film curvature and microemulsion morphology.

Leakage Account for Radial Face Contact Seal in Aircraft Engine Support

NASA Astrophysics Data System (ADS)

Vinogradov, A. S.; Sergeeva, T. V.

2018-01-01

The article is dedicated to the development of a methodology for the radial face contact seal design taking into consideration the supporting elements deformations in different aircraft engine operating modes. Radial face contact seals are popular in the aircraft engines bearing support. However, there are no published leakage calculation methodologies of these seals. Radial face contact seal leakage is determined by the gap clearance in the carbon seal ring split. In turn, the size gap clearance depends on the deformation of the seal assembly parts and from the engine operation. The article shows the leakage detection sequence in the intershaft radial face contact seal of the compressor support for take-off and cruising modes. Evaluated calculated leakage values (2.4 g/s at takeoff and 0.75 g/s at cruising) go with experience in designing seals.

Stress intensity and displacement coefficients for radially cracked ring segments subject to three-point bending

NASA Technical Reports Server (NTRS)

Gross, B.; Srawley, J. E.

1983-01-01

The boudary collocation method was used to generate Mode 1 stress intensity and crack mouth displacement coefficients for internally and externally radially cracked ring segments (arc bend specimens) subjected to three point radial loading. Numerical results were obtained for ring segment outer to inner radius ratios (R sub o/ R sub i) ranging from 1.10 to 2.50 and crack length to width ratios (a/W) ranging from 0.1 to 0.8. Stress intensity and crack mouth displacement coefficients were found to depend on the ratios R sub o/R sub i and a/W as well as the included angle between the directions of the reaction forces.

EIGHTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

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

Daugherty, W. L.

2013-09-03

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. Seventy tests using mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determine if they meet the criterion of leak-tightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. High temperature aging continues for 23more » GLT O-ring fixtures at 200 – 270 ºF. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The remaining GLT O-ring fixtures aging at 300 ºF have been retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 61 - 85 months, which is still bounding to O-ring temperatures during storage in KArea Complex (KAC). Based on expectations that the fixtures aging at 200 ºF will remain leaktight for a significant period yet to come, 2 additional fixtures began aging in 2011 at an intermediate temperature of 270 ºF, with hopes that they may reach a failure condition before the 200 ºF fixtures. High temperature aging continues for 6 GLT-S O-ring fixtures at 200 – 300 ºF. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 ºF. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 - 300 ºF for 41 - 45 months. Aging and periodic leak testing will continue for the remaining PCV fixtures.« less

Sealing glasses for titanium and titanium alloys

DOEpatents

Brow, Richard K.; Watkins, Randall D.

1992-01-01

Glass compositions containing CaO, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, SrO and BaO of various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with titanium and titanium alloys, for use in components such as seals for battery headers.

Sealing glasses for titanium and titanium alloys

DOEpatents

Brow, R.K.; Watkins, R.D.

1988-01-21

Glass compositions containing CaO, Al/sub 2/O/sub 3/, B/sub 2/O/sub 3/, SrO and BaO of various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with titanium and titanium alloys, for use in components such as seals for battery headers.

SIXTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

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

Daugherty, W.

2011-08-31

A series of experiments to monitor the aging performance of Viton{reg_sign} GLT O-rings used in the Model 9975 package has been ongoing for seven years at the Savannah River National Laboratory. Seventy tests using mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 F. They were leak-tested initially and have been tested periodically to determine if they meet the criterion of leak-tightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 F. High temperature aging continues formore » 33 GLT O-ring fixtures at 200-300 F. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 F and higher temperatures, and in 7 fixtures aging at 300 F. No failures have yet been observed in GLT O-ring fixtures aging at 200 F for 41-60 months, which is still bounding to O-ring temperatures during storage in K-Area Complex (KAC). Based on expectations that the fixtures aging at 200 F will remain leak-tight for a significant period yet to come, 2 additional fixtures began aging within the past year at an intermediate temperature of 270 F, with hopes that they may leak before the 200 F fixtures. High temperature aging continues for 6 GLT-S O-ring fixtures at 200-300 F. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 F. No failures have yet been observed in GLT-S O-ring fixtures aging at 200-300 F for up to 26 months. For O-ring fixtures that have failed the room temperature leak test and been disassembled, the Orings displayed a compression set ranging from 51-96%. This is greater than seen to date for packages inspected during KAC field surveillance (24% average). For GLT O-rings, separate service life estimates have been made based on the O-ring fixture leak test data and based on compression stress

Anti-diffusion metal coated O-rings

DOEpatents

Biallas, George Herman; Boyce, James Reid

2016-03-22

A method for inhibiting diffusion of gases and/or transmission of photons through elastomeric seals and a diffusion inhibiting elastomeric seal wherein at least a portion of the surface of a diffusion inhibiting elastomeric seal is coated with a compatibly-deformable, malleable metal coating.

Expanding Actin Rings Zipper the Mouse Embryo for Blastocyst Formation.

PubMed

Zenker, Jennifer; White, Melanie D; Gasnier, Maxime; Alvarez, Yanina D; Lim, Hui Yi Grace; Bissiere, Stephanie; Biro, Maté; Plachta, Nicolas

2018-04-19

Transformation from morula to blastocyst is a defining event of preimplantation embryo development. During this transition, the embryo must establish a paracellular permeability barrier to enable expansion of the blastocyst cavity. Here, using live imaging of mouse embryos, we reveal an actin-zippering mechanism driving this embryo sealing. Preceding blastocyst stage, a cortical F-actin ring assembles at the apical pole of the embryo's outer cells. The ring structure forms when cortical actin flows encounter a network of polar microtubules that exclude F-actin. Unlike stereotypical actin rings, the actin rings of the mouse embryo are not contractile, but instead, they expand to the cell-cell junctions. Here, they couple to the junctions by recruiting and stabilizing adherens and tight junction components. Coupling of the actin rings triggers localized myosin II accumulation, and it initiates a tension-dependent zippering mechanism along the junctions that is required to seal the embryo for blastocyst formation. Copyright © 2018 Elsevier Inc. All rights reserved.

The future of the application of the Bi-Digital O-Ring Test in Sports Psychology.

PubMed

Ozerkan, Kemal Nuri

2005-01-01

The Bi-Digital O-Ring Test, originally developed by Dr. Omura, utilizes changes in the degree of strength of voluntary movements of muscles of the fingers under a definite muscle tonus, making Bi-Digital O-Rings, as an indicator of pathology in the body. Research in Sports Psychology can use the classical measurement methods and Bi-Digital O-Ring Test method comparatively and thus produce new findings regarding the reliability and certainty of the Bi-Digital O-Ring Test test. It seems probable that by using the non-invasive Bi-Digital O-Ring Test test, it is possible to measure enzymes, hormones and neuro-transmitters instantaneously and assess a sports person's actual psychological and physiological performance, and thereby help them reach their peak performance levels during both exercise and competitions.

Oxidation-resisting technology of W-Re thermocouples and their industrial applications

NASA Astrophysics Data System (ADS)

Wang, K.; Dai, M.; Dong, J.; Wang, L.; Wang, T.

2013-09-01

We use DSC/TG, SEM and EPMA approaches to investigate the high temperature oxidation behaviors of the Type C W-Re thermocouple wires and W-Re powders which the wires were made from. To solve the oxidization of W-Re thermocouples the chemical method, other than the commonly used physical method, i.e. vacuum-pumping method, was developed. Several solid-packed techniques such as stuffing with inert material, chemical deoxidizing, gas-absorbing and sealing were employed to prevent the W-Re thermocouples from oxidizing. Based on comprehensive consideration of various parameters in process industries, a series of industrial W-Re thermocouples has been successfully used in oxidizing and reducing atmospheres, high temperature alkali and other harsh environments. The service life is 6 to 12 months in strong oxidizing atmosphere of Cr2O3-Al2O3 brick kiln and 2 to 3 months in high temperature alkali and in reducing atmosphere of CO.

Analysis of anti-neoplastic drug in bacterial ghost matrix, w/o/w double nanoemulsion and w/o nanoemulsion by a validated 'green' liquid chromatographic method.

PubMed

Youssof, Abdullah M E; Salem-Bekhit, Mounir M; Shakeel, Faiyaz; Alanazi, Fars K; Haq, Nazrul

2016-07-01

The objective of the present investigation was to develop and validate a 'green' reversed phase high-performance liquid chromatography (RP-HPLC) method for rapid analysis of a cytotoxic drug 5-fluorouracil (5-FU) in bulk drug, marketed injection, water-in-oil (w/o) nanoemulsion, double water-in-oil-in-water (w/o/w) nanoemulsion and bacterial ghost (BG) matrix. The chromatography study was carried out at room temperature (25±1°C) using an HPLC system with the help of ultraviolet (UV)-visible detector. The chromatographic performance was achieved with a Nucleodur 150mm×4.6mm RP C8 column filled with 5µm filler as a static phase. The mobile phase consisted of ethyl acetate: methanol (7:3% v/v) which was delivered at a flow rate of 1.0mLmin(-1) and the drug was detected in UV mode at 254nm. The developed method was validated in terms of linearity (r(2)=0.998), accuracy (98.19-102.09%), precision (% RSD=0.58-1.17), robustness (% RSD=0.12-0.53) and sensitivity with satisfactory results. The efficiency of the method was demonstrated by the assay of the drug in marketed injection, w/o nanoemulsion, w/o/w nanoemulsion and BG with satisfactory results. The successful resolution of the drug along with its degradation products clearly established the stability-indicating nature of the proposed method. Overall, these results suggested that the proposed analytical method could be effectively applied to the routine analysis of 5-FU in bulk drug, various pharmaceutical dosage forms and BG. Copyright © 2016 Elsevier B.V. All rights reserved.

Space Shuttle Orbital Maneuvering Subsystem (OMS) Engine Propellant Leakage Ball-Valve Shaft Seals

NASA Technical Reports Server (NTRS)

Lueders, Kathy; Buntain, Nick; Fries, Joseph (Technical Monitor)

1999-01-01

Evidence of propellant leakage across ball-valve shaft seals has been noted during the disassembly of five flight engines and one test engine at the NASA Lyndon B. Johnson Space Center, White Sands Test Facility. Based on data collected during the disassembly of these five engines, the consequences of propellant leakage across the ball-valve shaft seals can be divided into four primary areas of concern: Damage to the ball-valve pinion shafts, damage to sleeved bearings inside the ball-valve and actuator assemblies, degradation of the synthetic rubber o-rings used in the actuator assemblies, and corrosion and degradation to the interior of the actuator assemblies. The exact time at which leakage across the ball-valve shaft seals occurs has not been determined, however, the leakage most likely occurs during engine firings when, depending on the specification used, ball-valve cavity pressures range as high as 453 to 550 psia. This potential pressure range for the ball-valve cavities greatly exceeds the acceptance leakage test pressure of 332 psia. Since redesign and replacement of the ball-valve shaft seals is unlikely, the near term solution to prevent damage that occurs from shaft-seal leakage is to implement a routine overhaul and maintenance program for engines in the fleet. Recommended repair, verification, and possible preventative maintenance measures are discussed in the paper.

Influence of main emulsion components on the physicochemical and functional properties of W/O/W nano-emulsion: Effect of polyphenols, Hi-Cap, basil seed gum, soy and whey protein isolates.

PubMed

Delfanian, Mojtaba; Razavi, Seyed M A; Haddad Khodaparast, Mohammad Hossein; Esmaeilzadeh Kenari, Reza; Golmohammadzadeh, Shiva

2018-06-01

In this study, the effect of natural macromolecules as carrier agents on the biological activity of nano-encapsulated Bene hull polyphenols (Pistacia atlantica subsp. Mutica) through W/O/W emulsions was evaluated. The W/O microemulsions as primary emulsions and a complex of soy protein isolate and basil seed gum (SPI-BSG), whey protein isolate and basil seed gum (WPI-BSG) and also Hi-Cap 100 in the outer aqueous phase were used to produce W/O/W nano-emulsions. Z-average size of emulsions stabilized by Hi-Cap, WPI-BSG, and SPI-BSG was 318, 736.9 and 1918 nm, respectively. The encapsulation efficiency of polyphenols for powders produced by Hi-Cap, WPI-BSG, and SPI-BSG was 95.25, 90.9 and 92.88%, respectively, which was decreased to 72.47, 67.12 and 64.44% after 6 weeks storage at 30 °C. The antioxidant activity of encapsulated polyphenols at 100, 200 and 300 ppm was measured in oil by peroxide and p-anisidine values during storage and was compared to non-encapsulated extract and synthetic antioxidant. Results showed oxidative alterations in oils containing encapsulated polyphenols was lower than unencapsulated form, which among them capsules produced by SPI-BSG exhibited higher antioxidant effects due to the better gradual release. Generally, the higher antioxidant potential was achieved with increased solubility and controlled release of polyphenols through their nano-encapsulation. Copyright © 2018 Elsevier Ltd. All rights reserved.

PRELIMINARY REPORT: EFFECTS OF IRRADIATION AND THERMAL EXPOSURE ON ELASTOMERIC SEALS FOR CASK TRANSPORTATION AND STORAGE

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

Verst, C.; Skidmore, E.; Daugherty, W.

2014-05-30

A testing and analysis approach to predict the sealing behavior of elastomeric seal materials in dry storage casks and evaluate their ability to maintain a seal under thermal and radiation exposure conditions of extended storage and beyond was developed, and initial tests have been conducted. The initial tests evaluate the aging response of EPDM elastomer O-ring seals. The thermal and radiation exposure conditions of the CASTOR® V/21 casks were selected for testing as this cask design is of interest due to its widespread use, and close proximity of the seals to the fuel compared to other cask designs leading tomore » a relatively high temperature and dose under storage conditions. A novel test fixture was developed to enable compression stress relaxation measurements for the seal material at the thermal and radiation exposure conditions. A loss of compression stress of 90% is suggested as the threshold at which sealing ability of an elastomeric seal would be lost. Previous studies have shown this value to be conservative to actual leakage failure for most aging conditions. These initial results indicate that the seal would be expected to retain sealing ability throughout extended storage at the cask design conditions, though longer exposure times are needed to validate this assumption. The high constant dose rate used in the testing is not prototypic of the decreasingly low dose rate that would occur under extended storage. The primary degradation mechanism of oxidation of polymeric compounds is highly dependent on temperature and time of exposure, and with radiation expected to exacerbate the oxidation.« less

Investigating Low Temperature Properties of Rubber Seals - 13020

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

Jaunich, M.; Wolff, D.; Stark, W.

To achieve the required tightness levels of containers for low and intermediate level radioactive wastes rubbers are widely applied as main sealing materials. The save encapsulation of the radioactive container contents has to be guaranteed according to legislation and appropriate guidelines for long storage periods as well as down to temperatures of -40 deg. C during transportation. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of rubbers are strongly influenced by temperature. At low temperatures this is caused by the rubber-glass transition (abbr. glassmore » transition). During continuous cooling the material changes from rubber-like entropy-elastic to stiff energy-elastic behaviour, that allows nearly no strain or retraction. Therefore, rubbers are normally used above their glass transition but the minimum working temperature limit is not defined precisely, what can cause problems during application. The temperature range where full functionality is possible is strongly dependent on the application conditions and the material. For this investigation mainly ethylene propylene diene (EPDM) and fluorocarbon rubbers (FKM) were selected as they are often used for radioactive waste containers. Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are typically used for the determination of the temperature range of the glass transition process. The standardized compression set measurement according to ISO 815 is common for investigation of rubber sealing materials as the test simulates the seal behaviour after release. To reduce the test time of the standard tests a faster technique giving the same information was developed. Additionally, the breakdown temperature of the sealing function of complete O-ring seals is measured in a component test setup to compare it with the results of the other tests. The experimental setup is capable

Use of tear ring permits repair of sealed module circuitry

NASA Technical Reports Server (NTRS)

1965-01-01

Improved packaging technique for modular electronic circuitry utilizes a tear ring which may be removed for repair and resealed. The tear ring is put over the container and header to which the electronic circuit assembly has been attached.

Evaluation of selected elastomer O-ring pump seals for service at the Wilsonville, Alabama, Advanced Coal Liquefaction Research and Development Facility. [Ethylenepropylenediene monomer compounds

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

Skena, C.C.; Keiser, J.R.

1986-08-01

Previous laboratory tests of elastomer O-rings in coal liquefaction solvents conducted at L'Garde, Inc., indicated that certain ethylenepropylenediene monomer (EPDM) compounds provided the best performance when a backup ring was used to limit swelling. Before service testing in a pump at the Wilsonville, Alabama, Advanced Coal Liquefaction Research and Development Facility, tests of six selected elastomers in the appropriate Wilsonville-produced solvent were conducted at Oak Ridge National Laboratory (ORNL). The ORNL tests measured the elastomers' changes in cross section, weight, density, and relative flexibility. Although two perfluoroelastomers showed less degradation of most properties during these tests, it was decided tomore » proceed with service testing of two EPDM elastomers because of their much lower cost. 5 refs., 14 figs., 7 tabs.« less

Controlling the reaction between boron-containing sealing glass and a lanthanum-containing cathode by adding Nb2O5

NASA Astrophysics Data System (ADS)

Zhao, Dandan; Fang, Lihua; Tang, Dian; Zhang, Teng

2016-09-01

In solid oxide fuel cell (SOFC) stacks, the volatile boron species present in the sealing glass often react with the lanthanum-containing cathode, degrading the activity of the cathode (this phenomenon is known as boron poisoning). In this work, we report that this detrimental reaction can be effectively reduced by doping bismuth-containing borosilicate sealing glass-ceramic with a niobium dopant. The addition of Nb2O5 not only condenses the [SiO4] structural units in the glass network, but also promotes the conversion of [BO3] to [BO4]. Moreover, the Nb2O5 dopant enhances the formation of boron-containing phases (Ca3B2O6 and CaB2Si2O8), which significantly reduces the volatility of boron compounds in the sealing glass, suppressing the formation of LaBO3 in the reaction couple between the glass and the cathode. The reported results provide a new approach to solve the problem of boron poisoning.

Crosslinking of SAVY-4000 O-rings as a Function of Aging Conditions

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

Van Buskirk, Caleb Griffith

SAVY-4000 containers were developed as a part of DOE M 441.1-1 to protect workers who handle stored nuclear material from exposure due to loss of containment.1 The SAVY-4000 is comprised of three parts: a lid, a container, and a cross-linked fluoropolymer O-ring. Degradation of the O-ring during use could limit the lifetime of the SAVY-4000. In order to quantify the chemical changes of the Oring over time, the molecular weight between crosslinks was determined as a function of aging conditions using a swelling technique. Because the O-ring is a cross-linked polymer, it will absorb solvent into its matrix without dissolving.more » The relative amount of solvent uptake can be related to the degree of crosslinking using an equation developed by Paul Flory and John Rehner Jr3. This method was used to analyze O-ring samples aged under thermal and ionizing-radiation conditions. It was found that at the harsher thermal gaining conditions in absence of ionizing-radiation the average molecular weight between crosslinks decreased, indicating a rise in crosslinks, which may be attributable to advanced aging with no ionizing radiation present. Inversely, in the presence of ionizing radiation it was found that material has a higher level of cross-linking with age. This information could be used to help predict the lifetime of the O-rings in SAVY-4000 containers under service conditions.« less

An MPL W515L mutation in refractory anemia with ringed sideroblasts associated with marked thrombocytosis: A case report.

PubMed

Hao, Lin; Sen, Sandeep; Sugumar, Dhivya

2015-02-01

The current study presents the case of a 63-year-old patient exhibiting refractory anemia with ringed sideroblasts associated with marked thrombocytosis (RARS-T), who was positive for the MPL W515L mutation, but negative for the JAK2 V617F mutation. Following diagnosis, the patient remained asymptomatic for over three years, however, in August 2012, the patient relapsed and was administered with supportive treatment in the form of subcutaneous darbepoetin α at a dose of 300 μg/week, which resulted in an increased hemoglobin concentration, allowing the patient to remain transfusion-independent. The MPL W515L mutation has been reported in two previous cases of myelodysplastic/myeloproliferative neoplasms (MDS/MPN) with ringed sideroblasts, however, to the best of our knowledge, the current report is the first to present a case of RARS-T with an MPL W515L mutation. A clinical trial designed to evaluate the efficacy of a targeted agent against the JAK2 V617F mutation is currently ongoing, with the aim of providing a novel therapeutic strategy for treating MDS/MPN patients. As MPL is located upstream of the JAK-STAT signaling pathway, it is a possible therapeutic target in MDS/MPN patients positive for an MPL W515L mutation, but negative for a JAK2 V617F mutation.

The thermal and mechanical deformation study of up-stream pumping mechanical seal

NASA Astrophysics Data System (ADS)

Chen, H. L.; Xu, C.; Zuo, M. Z.; Wu, Q. B.

2015-01-01

Taking the viscosity-temperature relationship of the fluid film into consideration, a 3-D numerical model was established by ANSYS software which can simulate the heat transfer between the upstream pumping mechanical seal stationary and rotational rings and the fluid film between them as well as simulate the thermal deformation, structure deformation and the coupling deformation of them. According to the calculation result, thermal deformation causes the seal face expansion and the maximum thermal deformation appears at the inside of the seal ring. Pressure results in a mechanical deformation, the maximum deformation occurs at the top of the spiral groove and the overall trend is inward the mating face, opposite to the thermal deformation. The coupling deformation indicate that the thermal deformation can be partly counteracted by pressure deformation. Using this model, the relationship between deformation and shaft speed and the sealing liquid pressure was studied. It's found that the shaft speed will both enhance the thermal and structure deformation and the fluid pressure will enhance the structure deformation but has little to do with the thermal deformation. By changing the sealing material, it's found that material with low thermal expansion coefficient and low elastic modulus will suffer less thermal-pressure deformation.

Eleventh interim status report: Model 9975 O-Ring fixture long-term leak performance

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

Daugherty, W.

2016-08-01

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperature. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determinemore » if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF.« less

Tenth interim status report: Model 9975 O-ring fixture long-term leak performance

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

Daugherty, W. L.

2015-08-26

A series of experiments to monitor the aging performance of Viton ® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperatures. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups were assembled and heated to temperatures ranging from 200 to 450 °F. They were leak-tested initially and have been tested periodically tomore » determine if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 °F.« less

Surface damages of polycrystalline W and La2O3-doped W induced by high-flux He plasma irradiation

NASA Astrophysics Data System (ADS)

Liu, Lu; Li, Shouzhe; Liu, Dongping; Benstetter, Günther; Zhang, Yang; Hong, Yi; Fan, Hongyu; Ni, Weiyuan; Yang, Qi; Wu, Yunfeng; Bi, Zhenhua

2018-04-01

In this study, polycrystalline tungsten (W) and three oxide dispersed strengthened W with 0.1 vol %, 1.0 vol % and 5.0 vol % lanthanum trioxide (La2O3) were irradiated with low-energy (200 eV) and high-flux (5.8 × 1021 or 1.4 × 1022 ions/m2ṡs) He+ ions at elevated temperature. After He+ irradiation at a fluence of 3.0 × 1025/m2, their surface damages were observed by scanning electron microscopy, energy dispersive spectroscopy, scanning electron microscopy-electron backscatter diffraction, and conductive atomic force microscopy. Micron-sized holes were formed on the surface of W alloys after He+ irradiation at 1100 K. Analysis shows that the La2O3 grains doped in W were sputtered preferentially by the high-flux He+ ions when compared with the W grains. For irradiation at 1550 K, W nano-fuzz was formed at the surfaces of both polycrystalline W and La2O3-doped W. The thickness of the fuzz layers formed at the surface of La2O3-doped W is 40% lower than the one of polycrystalline W. The presence of La2O3 could suppress the diffusion and coalescence of He atoms inside W, which plays an important role in the growth of nanostructures fuzz.

Seal glass compatibility with bare and (Mn,Co) 3O 4 coated Crofer 22 APU alloy in different atmospheres

NASA Astrophysics Data System (ADS)

Mahapatra, M. K.; Lu, K.

To prevent gas mixing and leakage during solid oxide fuel/electrolyzer cell operation, the interconnect/seal glass interface should bond well and remain stable. A SrO-La 2O 3-Al 2O 3-SiO 2 (SABS-0) seal glass has been bonded to bare Crofer 22 APU alloy and (Mn,Co) 3O 4 coated Crofer 22 APU alloy. The stability of the interconnect/SABS-0 interface has been studied in air and H 2/H 2O atmospheres at 800 °C for 1000 h. The interconnect/seal glass interaction involves the oxidation of the bare and (Mn,Co) 3O 4 coated Crofer 22 APU alloy surfaces, inter-diffusion of elements, chemical reaction, and the devitrification of the SABS-0 glass. The study shows that the thermal treatment atmosphere greatly affects the interfacial stability of both bare Crofer 22 APU/SABS-0 and (Mn,Co) 3O 4 coated Crofer 22 APU/SABS-0 samples. The interfacial stability is better in the H 2/H 2O atmosphere for both samples. The instability of the (Mn,Co) 3O 4 coating under the thermal treatment conditions degrades the interfacial compatibility of the (Mn,Co) 3O 4 coated Crofer 22 APU/SABS-0 sample.

Effect of Substitution on the Aniline Moiety of the GPR88 Agonist 2-PCCA: Synthesis, Structure-Activity Relationships, and Molecular Modeling Studies.

PubMed

Jin, Chunyang; Decker, Ann M; Harris, Danni L; Blough, Bruce E

2016-10-19

GPR88, an orphan receptor richly expressed in the striatum, is implicated in a number of basal ganglia-associated disorders. In order to elucidate the functions of GPR88, an in vivo probe appropriate for CNS investigation is required. We previously reported that 2-PCCA was able to modulate GPR88-mediated cAMP production through a Gα i -coupled pathway. Early structure-activity relationship (SAR) studies suggested that the aniline moiety of 2-PCCA is a suitable site for diverse modifications. Aimed at elucidating structural requirements in this region, we have designed and synthesized a series of analogues bearing a variety of substituents at the phenyl ring of the aniline moiety. Several compounds (e.g., 5j, 5o) showed improved or comparable potency, but have lower lipophilicity than 2-PCCA (clogP 6.19). These compounds provide the basis for further optimization to probe GPR88 in vivo functions. Computational studies confirmed the SAR trends and supported the notion that 4'-substituents on the biphenyl ring exit through a largely hydrophobic binding site to the extracellular loop.

Sample Containerization and Sealing Techniques for Contamination Prevention and Preservation of Science Value for Mars Sample Return

NASA Astrophysics Data System (ADS)

Younse, Paulo

Four sealing methods for encapsulating samples in 1 cm diameter thin-walled sample tubes were designed, along with a set of tests for characterization and evaluation of contamination prevention and sample preservation capability for the proposed Mars Sample Return (MSR) campaign. The sealing methods include a finned shape memory alloy (SMA) plug, expanding torque plug, contracting SMA ring cap, and expanding SMA ring plug. Mechanical strength and hermeticity of the seal were measured using a helium leak detector. Robustness of the seal to Mars simulant dust, surface abrasion, and pressure differentials were tested. Survivability tests were run to simulate thermal cycles on Mars, vibration from a Mars Ascent Vehicle (MAV), and shock from Earth Entry Vehicle (EEV) landing. Material compatibility with potential sample minerals and organic molecules were studied to select proper tube and seal materials that would not lead to adverse reactions nor contaminate the sample. Cleaning and sterilization techniques were executed on coupons made from the seal materials to assess compliance with planetary protection and contamination control. Finally, a method to cut a sealed tube for sample removal was designed and tested.

49 CFR 179.400-9 - Stiffening rings.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Stiffening rings. 179.400-9 Section 179.400-9... on each side of the attachment of the stiffening ring is given by the following formula: W = 0.78(Rt)0.5 Where: W = width of jacket effective on each side of the stiffening ring, in inches; R = outside...

Hot piston ring tests

NASA Technical Reports Server (NTRS)

Allen, David J.; Tomazic, William A.

1987-01-01

As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

A comparative study on the capacity of a range of food-grade particles to form stable O/W and W/O Pickering emulsions.

PubMed

Duffus, Laudina J; Norton, Jennifer E; Smith, Paul; Norton, Ian T; Spyropoulos, Fotios

2016-07-01

Whilst literature describing edible Pickering emulsions is becoming increasingly available, current understanding of these systems still suffers from a lack of consistency in terms of the (processing and formulation) conditions within which these structures have been studied. The current study aims to provide a comparative analysis of the behaviour of different edible Pickering candidates and their ability to stabilise emulsion droplets, under well-controlled and uniform experimental conditions, in order to clearly identify the particle properties necessary for successful Pickering functionality. More specifically, an extensive investigation into the suitability of various food-grade material to act as Pickering particles and provide stable oil-in-water (O/W) and water-in-oil (W/O) emulsions was carried out. Polysaccharide and flavonoid particles were characterised in terms of their size, ζ-potential, interfacial activity and wettability, under equivalent conditions. Particles were subsequently used to stabilise 20% w/w O/W and W/O emulsions, in the absence of added surfactant or other known emulsifying agents, through different processing routes. All formed Pickering emulsions were shown to resist significant droplet size variation and remain stable at particle concentrations between 2 and 3% w/w. The main particle prerequisites for successful Pickering stabilisation were: particle size (200nm - 1μm); an affinity for the emulsion continuous phase and a sufficient particle charge to extend stability. Depending upon the employed emulsification process, the resulting emulsion formation and stability behaviour can be reasonably predicted a priori from the evaluation of specific particle characteristics. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

A Novel CMOS Multi-band THz Detector with Embedded Ring Antenna

NASA Astrophysics Data System (ADS)

Xu, Lei-jun; Guan, Jia-ning; Bai, Xue; Li, Qin; Mao, Han-ping

2017-10-01

To overcome the large chip area occupation for the traditional terahertz multi-frequency detector by using the antenna elements in a different frequency, a novel structure for a multi-frequency detector is proposed and studied. Based on the ring antenna detector, an embedded multi-ring antenna with multi-port is proposed for the multi-frequency detector. A single-ring and dual-ring detectors are analyzed and designed in 0.18 μ m CMOS. For the single-ring detector, the best responsivity and NEP is 701 V/W and 261 pW/Hz0.5 at the frequency of 290 GHz. For the dual-ring detector, the best responsivity is 367 V/W and 297 V/W, NEP is 578 pW/Hz0.5 and 713pW/Hz0.5, at the frequency of 600 GHz and 806 GHz, respectively. This embedded multi-ring detector has a simple structure which can be expanded easily in a compact size.

Aging Behavior of the EPDM O-Rings in the H1616 Shipping Package

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

Daugherty, W.; Stefek, T.; Skidmore, E.

The H1616 shipping package is used within the DOE complex for shipping tritium reservoirs. The annual recertification frequency can create logistical difficulties with other constraints on the timing of shipments; thus, a longer re-certification period is desirable. The ethylene propylene diene monomer (EPDM) O-rings used in the H1616 shipping package are being aged and tested at the Savannah River National Laboratory (SRNL) to provide a technical basis for extending the annual maintenance of the H1616 shipping package. H1616 EPDM O-rings are being aged at elevated temperature, and tested for degradation in mechanical properties, compression stress relaxation (CSR) behavior, and leakmore » performance. Mechanical properties of aged O-rings show significant degradation can occur, but an inert atmosphere (argon backfill) greatly reduces the rate of degradation. The CSR behavior of O-rings was evaluated in air at 79 to 177 °C. These collective data were used to develop a predictive model for extrapolation of CSR behavior to relevant service temperatures (<67 °C). O-rings were also aged in H1616 Containment Vessels (CV) in an inert atmosphere at 71 to 149 °C. The vessels are helium leak tested periodically to determine if they continue to remain leak-tight. The vessel tests provide a solid demonstration that the H1616 O-rings will remain leak-tight at temperatures up to 113 °C for up to approximately 2.3 years. Significantly longer periods of leak-tight service are expected at the lower temperatures actually experienced in service. The predictive model developed from the CSR data conservatively indicates a service life of ~5 years at 67 °C. Although the relationship between CSR behavior and leak-tight performance has not been established for this design, the CSR predictions for this O-ring are conservative relative to leak-tight performance. Based on the collective data developed to date, SRNL has recommended that the maintenance interval for the H1616 package

Coencapsulation of (-)-Epigallocatechin-3-gallate and Quercetin in Particle-Stabilized W/O/W Emulsion Gels: Controlled Release and Bioaccessibility.

PubMed

Chen, Xing; McClements, David Julian; Wang, Jian; Zou, Liqiang; Deng, Sumeng; Liu, Wei; Yan, Chi; Zhu, Yuqing; Cheng, Ce; Liu, Chengmei

2018-04-11

Particle-stabilized W 1 /O/W 2 emulsion gels were fabricated using a two-step procedure: ( i) a W 1 /O emulsion was formed containing saccharose (for osmotic stress balance) and gelatin (as a gelling agent) in the aqueous phase and polyglycerol polyricinoleate (a lipophilic surfactant) in the oil phase; ( ii) this W 1 /O emulsion was then homogenized with another water phase (W 2 ) containing wheat gliadin nanoparticles (hydrophilic emulsifier). The gliadin nanoparticles in the external aqueous phase aggregated at pH 5.5, which led to the formation of particle-stabilized W 1 /O/W 2 emulsion gels with good stability to phase separation. These emulsion gels were then used to coencapsulate a hydrophilic bioactive (epigallocatechin-3-gallate, EGCG) in the internal aqueous phase (encapsulation efficiency = 65.5%) and a hydrophobic bioactive (quercetin) in the oil phase (encapsulation efficiency = 97.2%). The emulsion gels improved EGCG chemical stability and quercetin solubility under simulated gastrointestinal conditions, which led to a 2- and 4-fold increase in their effective bioaccessibility, respectively.

Heat generation and hemolysis at the shaft seal in centrifugal blood pumps.

PubMed

Araki, K; Taenaka, Y; Wakisaka, Y; Masuzawa, T; Tatsumi, E; Nakatani, T; Baba, Y; Yagura, A; Eya, K; Toda, K

1995-01-01

The heat and hemolysis around a shaft seal were investigated. Materials were original pumps (Nikkiso HMS-15:N-original, and 3M Delphin:D-original), vane-removed pumps (Nvane(-), Dvane(-)), and a small chamber with a shaft coiled by nichrome wire (mock pump). The original pumps were driven at 500 mmHg and 5 L/min, and vane-removed pumps were driven at the same rotation number. An electrical powers of 0, 0.5, 2, and 10 W was supplied to the mock pumps. In vitro hemolytic testing showed that hemolytic indices were 0.027 g/100 L in N-original, 0.013 in Nvane(-), 0.061 in D-original, and 0.012 in Dvane(-). Measurement of heat with a thermally insulated water chamber showed total heat within the pump of 8.62 and 10.85 W, and heat at the shaft seal of 0.87 and 0.62 W in the Nikkiso and Delphin pumps, respectively. Hemolysis and heat generation of mock pumps remained low. The results indicate that the heat generated around the shaft seal was minimal. Hemolysis at the shaft-seal was considerable but not major. Local heat did not affect hemolysis. It was concluded that the shaft-seal affected hemolysis, not by local heat but friction itself.

1.5 W high efficiency and tunable single-longitudinal-mode Ho:YLF ring laser based on Faraday effect.

PubMed

Wu, Jing; Ju, Youlun; Dai, Tongyu; Yao, Baoquan; Wang, Yuezhu

2017-10-30

We demonstrated an efficient and tunable single-longitudinal-mode Ho:YLF ring laser based on Faraday effect for application to measure atmospheric carbon dioxide (CO 2 ). Single-longitudinal-mode power at 2051.65 nm achieved 528 mW with the slope efficiency of 39.5% and the M 2 factor of 1.07, and the tunable range of about 178 GHz was obtained by inserting a Fabry-Perot (F-P) etalon with the thickness of 0.5 mm. In addition, the maximum single-longitudinal-mode power reached 1.5 W with the injected power of 528 mW at 2051.65 nm by master oscillator power amplifier (MOPA) technique. High efficiency and tunable single-longitudinal-mode based on Faraday effect around 2 μm has not been reported yet to the best of our knowledge.

One-step formation of w/o/w multiple emulsions stabilized by single amphiphilic block copolymers.

PubMed

Hong, Liangzhi; Sun, Guanqing; Cai, Jinge; Ngai, To

2012-02-07

Multiple emulsions are complex polydispersed systems in which both oil-in-water (O/W) and water-in-oil (W/O) emulsion exists simultaneously. They are often prepared accroding to a two-step process and commonly stabilized using a combination of hydrophilic and hydrophobic surfactants. Recently, some reports have shown that multiple emulsions can also be produced through one-step method with simultaneous occurrence of catastrophic and transitional phase inversions. However, these reported multiple emulsions need surfactant blends and are usually described as transitory or temporary systems. Herein, we report a one-step phase inversion process to produce water-in-oil-in-water (W/O/W) multiple emulsions stabilized solely by a synthetic diblock copolymer. Unlike the use of small molecule surfactant combinations, block copolymer stabilized multiple emulsions are remarkably stable and show the ability to separately encapsulate both polar and nonpolar cargos. The importance of the conformation of the copolymer surfactant at the interfaces with regards to the stability of the multiple emulsions using the one-step method is discussed.

Long-term changes of mercury levels in ringed seal (Phoca hispida) from Amundsen Gulf, and beluga (Delphinapterus leucas) from the Beaufort Sea, western Canadian Arctic.

PubMed

Outridge, P M; Hobson, K A; Savelle, J

2009-11-15

Mercury (Hg) concentrations were determined in the canine teeth of ringed seals (Phoca hispida) harvested during the 13th-14th, late 19th and early 21st Centuries in Amundsen Gulf, Northwest Territories, Canada. Most historical and pre-industrial teeth contained undetectable Hg levels (i.e. <1.0 ng/g DW), whereas samples from 2001-03 contained up to 12 ng/g DW in an age-dependent pattern. Assuming a median [Hg] value in 13th-14th Century teeth of half the detection limit (i.e. 0.5 ng/g DW), geometric means of Hg in modern teeth were 9-17 times those of seals in the 14th Century, equivalent to an anthropogenic input of 89-94% of total Hg in modern seals. These results corroborate a previous study of beluga (Delphinapterus leucas) in the nearby Beaufort Sea. While the seals' trophic position (inferred from delta(15)N values) did not change over time, modern delta(13)C values were lower by about 2 per thousand than in the 14th and 19th Centuries. This could be due to increased dissolution of anthropogenically derived CO(2) in the ocean from the atmosphere, but could also indicate more offshore pelagic feeding by modern seals, which might be a factor in their Hg exposure. New tooth [Hg] data are also presented for the Beaufort Sea beluga, using recently-discovered museum samples collected in 1960/61, which showed that most of the anthropogenic contribution to beluga Hg had already taken effect by 1960 (reaching approximately 75% of total Hg). Taken together, the long-term seal and beluga data indicate that whereas Hg levels in the marine ecosystems of the western Canadian Arctic were probably unchanged from pre-industrial times up to the late 19th Century, there was a significant, many-fold increase in the early to mid-20th Century, but little or no change after about the early 1960s.

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.

Development of seals for a geothermal downhole intensifier. Progress report

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

Captain, K.M.; Harvey, A.C.; Caskey, B.C.

1985-08-01

A system using high-velocity fluid jets in conjunction with a rotary diamond bit is currently considered as the best candidate for reducing the cost of drilling geothermal wells. Technical, safety and cost considerations indicate that the required jet supply pressure can best be established by a downhole pressure intensifier. Key intensifier components are the check valve and plunger seals, which must prevent leakage of the high-pressure, high-temperature abrasive fluid (drilling mud). To achieve the required performance, novel ceramic seals are currently being developed. The check valve seal includes a tapered polymeric plug and ceramic stop acting against a ceramic seat.more » The ceramic plunger seal is a variant of the ''stepped-joint'' piston ring and is designed to minimize contact pressure and abrasive wear. Initial testing of these seals in the laboratory shows encouraging results; design refinement and further testing is in progress. 2 refs., 6 figs., 3 tabs.« less

A New Tribological Test for Candidate Brush Seal Materials Evaluation

NASA Technical Reports Server (NTRS)

Fellenstein, James A.; Dellacorte, Christopher

1994-01-01

A new tribological test for candidate brush seal materials evaluation has been developed. The sliding contact between the brush seal wires and their mating counterface journal is simulated by testing a small tuft of wire against the outside diameter of a high speed rotating shaft. The test configuration is similar to a standard block on ring geometry. The new tester provides the capability to measure both the friction and wear of candidate wire and counterface materials under controlled loading conditions in the gram to kilogram range. A wide test condition latitude of speeds (1 to 27 m/s), temperatures (25 to 700 C), and loads (0.5 to 10 N) enables the simulation of many of the important tribological parameters found in turbine engine brush seals. This paper describes the new test rig and specimen configuration and presents initial data for candidate seal materials comparing tuft test results and wear surface morphology to field tested seal components.

Excitation of O+ Band EMIC Waves Through H+ Ring Velocity Distributions: Van Allen Probe Observations

NASA Astrophysics Data System (ADS)

Yu, Xiongdong; Yuan, Zhigang; Huang, Shiyong; Yao, Fei; Wang, Dedong; Funsten, Herbert O.; Wygant, John R.

2018-02-01

A typical case of electromagnetic ion cyclotron (EMIC) emissions with both He+ band and O+ band waves was observed by Van Allen Probe A on 14 July 2014. These emissions occurred in the morning sector on the equator inside the plasmasphere, in which region O+ band EMIC waves prefer to appear. Through property analysis of these emissions, it is found that the He+ band EMIC waves are linearly polarized and propagating quasi-parallelly along the background magnetic field, while the O+ band ones are of linear and left-hand polarization and propagating obliquely with respect to the background magnetic field. Using the in situ observations of plasma environment and particle data, excitation of these O+ band EMIC waves has been investigated with the linear growth theory. The calculated linear growth rate shows that these O+ band EMIC waves can be locally excited by ring current protons with ring velocity distributions. The comparison of the observed wave spectral intensity and the calculated growth rate suggests that the density of H+ rings providing the free energy for the instability has decreased after the wave grows. Therefore, this paper provides a direct observational evidence to the excitation mechanism of O+ band EMIC waves: ring current protons with ring distributions provide the free energy supporting the instability in the presence of rich O+ in the plasmasphere.

Preparation of Zr(Mo,W)2O8 with a larger negative thermal expansion by controlling the thermal decomposition of Zr(Mo,W)2(OH,Cl)2∙2H2O.

PubMed

Petrushina, Mariya Yu; Dedova, Elena S; Filatov, Eugeny Yu; Plyusnin, Pavel E; Korenev, Sergei V; Kulkov, Sergei N; Derevyannikova, Elizaveta A; Sharafutdinov, Marat R; Gubanov, Alexander I

2018-03-28

Solid solutions of Zr(Mo,W) 2 O 7 (OH,Cl) 2 ∙2H 2 O with a preset ratio of components were prepared by a hydrothermal method. The chemical composition of the solutions was determined by energy dispersive X-ray spectroscopy (EDX). For all the samples of ZrMo x W 2-x O 7 (OH,Cl) 2 ∙2H 2 O (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0), TGA and in situ powder X-ray diffraction (PXRD) studies (300-1100 K) were conducted. For each case, the boundaries of the transformations were determined: Zr(Mo,W) 2 O 7 (OH,Cl) 2 ∙2H 2 O → orthorhombic-ZrMo x W 2-x O 8 (425-525 K), orthorhombic-ZrMo x W 2-x O 8  → cubic-ZrMo x W 2-x O 8 (700-850 K), cubic-ZrMo x W 2-x O 8  → trigonal-ZrMo x W 2-x O 8 (800-1050 K for x > 1) and cubic-ZrMo x W 2-x O 8  → oxides (1000-1075 K for x ≤ 1). The cell parameters of the disordered cubic-ZrMo x W 2-x O 8 (space group Pa-3) were measured within 300-900 K, and the thermal expansion coefficients were calculated: -3.5∙10 -6  - -4.5∙10 -6  K -1 . For the ordered ZrMo 1.8 W 0.2 O 8 (space group P2 1 3), a negative thermal expansion (NTE) coefficient -9.6∙10 -6  K -1 (300-400 K) was calculated. Orthorhombic-ZrW2O 8 is formed upon the decomposition of ZrW 2 O 7 (OH,Cl) 2 ∙2H 2 O within 500-800 K.

Tunable stability of monodisperse secondary O/W nano-emulsions

NASA Astrophysics Data System (ADS)

Vecchione, R.; Ciotola, U.; Sagliano, A.; Bianchini, P.; Diaspro, A.; Netti, P. A.

2014-07-01

Stable and biodegradable oil in water (O/W) nano-emulsions can have a huge impact on a wide range of bio-applications, from food to cosmetics and pharmaceuticals. Emulsions, however, are immiscible systems unstable over time; polymer coatings are known to be helpful, but an effective procedure to stabilize monodisperse and biodegradable O/W nano-emulsions is yet to be designed. Here, we coat biodegradable O/W nano-emulsions with a molecular layer of biodegradable polyelectrolytes such as polysaccharides - like chitosan - and polypeptides - like polylysine - and effectively re-disperse and densify the polymer coating at high pressure, thus obtaining monodisperse and stable systems. In particular, focusing on chitosan, our tests show that it is possible to obtain unprecedented ultra-stable O/W secondary nano-emulsions (diameter sizes tunable from ~80 to 160 nm and polydispersion indices below 0.1) by combining this process with high concentrations of polymers. Depending on the polymer concentration, it is possible to control the level of coating that results in a tunable stability ranging from a few weeks to several months. The above range of concentrations has been investigated using a fluorescence-based approach with new insights into the coating evolution.Stable and biodegradable oil in water (O/W) nano-emulsions can have a huge impact on a wide range of bio-applications, from food to cosmetics and pharmaceuticals. Emulsions, however, are immiscible systems unstable over time; polymer coatings are known to be helpful, but an effective procedure to stabilize monodisperse and biodegradable O/W nano-emulsions is yet to be designed. Here, we coat biodegradable O/W nano-emulsions with a molecular layer of biodegradable polyelectrolytes such as polysaccharides - like chitosan - and polypeptides - like polylysine - and effectively re-disperse and densify the polymer coating at high pressure, thus obtaining monodisperse and stable systems. In particular, focusing on

STS-88 Crew Portrait

NASA Technical Reports Server (NTRS)

1998-01-01

Five NASA astronauts and a Russian cosmonaut assigned to the STS-88 mission pose for a crew portrait. Seated in front (left to right) are mission specialists Sergei K. Krikalev, representing the Russian Space Agency (RSA), and astronaut Nancy J. Currie. In the rear from the left, are astronauts Jerry L. Ross, mission specialist; Robert D. Cabana, mission commander; Frederick W. 'Rick' Sturckow, pilot; and James H. Newman, mission specialist. The STS-88 mission launched aboard the Space Shuttle Endeavor on December 4, 1998 at 2:35 a.m. (CST) to deliver the Unity Node to the International Space Station (ISS).

Single-ring magnetic cusp low gas pressure ion source

DOEpatents

Bacon, Frank M.; Brainard, John P.; O'Hagan, James B.; Walko, Robert J.

1985-01-01

A single-ring magnetic cusp low gas pressure ion source designed for use in a sealed, nonpumped neutron generator utilizes a cathode and an anode, three electrically floating electrodes (a reflector behind the cathode, a heat shield around the anode, and an aperture plate), together with a single ring-cusp magnetic field, to establish and energy-filtering mechanism for producing atomic-hydrogen ions.

Co-occurring species differ in tree-ring δ18O trends.

Treesearch

John D. Marshall; Robert A. Monserud

2006-01-01

The stable oxygen isotope ratio (δ18O) of tree-ring cellulose is jointly determined by the δ18O of xylem water, the δ18O of atmospheric water vapor, the humidity of the atmosphere and perhaps by species-specific differences in leaf structure and function. Atmospheric...

Size analysis of nanoparticles extracted from W/O emulsions.

PubMed

Nagelreiter, C; Kotisch, H; Heuser, T; Valenta, C

2015-07-05

Nanosized particles are frequently used in many different applications, especially TiO2 nanoparticles as physical filters in sunscreens to protect the skin from UV radiation. However, concerns have arisen about possible health issues caused by nanoparticles and therefore, the assessment of the occurrence of nanoparticles is important in pharmaceutical and cosmetic formulations. In a previous work of our group, a method was presented to extract nanoparticles from O/W emulsions. But to respond to the needs of dry and sensitive skin, sunscreens of the water-in-oil emulsion type are available. In these, assessment of present nanoparticles is also an important issue, so the present study offers a method for extracting nanoparticles from W/O emulsions. Both methods emanate from the same starting point, which minimizes both effort and cost before the beginning of the assessment. By addition of NaOH pellets and centrifugation, particles were extracted from W/O emulsions and measured for their size and surface area by laser diffraction. With the simple equation Q=A/S a distinction between nanoparticles and microparticles was achieved in W/O emulsions, even in commercially available samples. The present method is quick and easy to implement, which makes it cost-effective. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication of low thermal expansion SiC/ZrW2O8 porous ceramics

NASA Astrophysics Data System (ADS)

Poowancum, A.; Matsumaru, K.; Juárez-Ramírez, I.; Torres-Martínez, L. M.; Fu, Z. Y.; Lee, S. W.; Ishizaki, K.

2011-03-01

Low or zero thermal expansion porous ceramics are required for several applications. In this work near zero thermal expansion porous ceramics were fabricated by using SiC and ZrW2O8 as positive and negative thermal expansion materials, respectively, bonded by soda lime glass. The mixture of SiC, ZrW2O8 and soda lime glass was sintered by Pulsed Electric Current Sintering (PECS, or sometimes called Spark Plasma Sintering, SPS) at 700 °C. Sintered samples with ZrW2O8 particle size smaller than 25 μm have high thermal expansion coefficient, because ZrW2O8 has the reaction with soda lime glass to form Na2ZrW3O12 during sintering process. The reaction between soda lime glass and ZrW2O8 is reduced by increasing particle size of ZrW2O8. Sintered sample with ZrW2O8 particle size 45-90 μm shows near zero thermal expansion.

Growth And Gas Sensing Properties Of Dielectrophoretically Isolated CuO-W{sub 18}O{sub 49} Heterostructures

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

Jain, Chhavi; Mukund, Vignesh; Kaur, Manmeet

2010-12-01

Hierarchical heterostructures consisting of W{sub 18}O{sub 49} nanowires grown on CuO nanowires have been prepared and studied for their gas sensing properties. SEM images show that W{sub 18}O{sub 49} initially grow as an shell over core CuO nanowire with protusion like branches whose thickness depends on oxygen partial pressure. These CuO:W{sub 18}O{sub 49} structures were dielectrophoretically isolated and studied for their gas sensing properties. The results show potential of use of tailored hierarchical heterostructures for the fabrication of gas sensors.

Enhanced Corrosion Resistance of PVD-CrN Coatings by ALD Sealing Layers

NASA Astrophysics Data System (ADS)

Wan; Zhang, Teng Fei; Ding, Ji Cheng; Kim, Chang-Min; Park, So-Won; Yang, Yang; Kim, Kwang-Ho; Kwon, Se-Hun

2017-04-01

Multilayered hard coatings with a CrN matrix and an Al2O3, TiO2, or nanolaminate-Al2O3/TiO2 sealing layer were designed by a hybrid deposition process combined with physical vapor deposition (PVD) and atomic layer deposition (ALD). The strategy was to utilize ALD thin films as pinhole-free barriers to seal the intrinsic defects to protect the CrN matrix. The influences of the different sealing layers added in the coatings on the microstructure, surface roughness, and corrosion behaviors were investigated. The results indicated that the sealing layer added by ALD significantly decreased the average grain size and improved the corrosion resistance of the CrN coatings. The insertion of the nanolaminate-Al2O3/TiO2 sealing layers resulted in a further increase in corrosion resistance, which was attributed to the synergistic effect of Al2O3 and TiO2, both acting as excellent passivation barriers to the diffusion of corrosive substances.

Nuclear Rings in the IR: Hidden Super Star Clusters

NASA Astrophysics Data System (ADS)

Maoz, Dan

1997-07-01

We propose NICMOS broad-band {F160W, F187W} and Paschen Alpha {F187N} imaging of nuclear starburst rings in two nearby galaxies. We already have UV {F220W} FOC data, and are scheduled to obtain WFPC2 images in U, V, I, and Halpha+[NII] of these rings. The rings contain large populations of super star clusters similar to those recently discovered in other types of starburst systems. Nuclear rings contain large numbers of these clusters in relatively unobscured starburst environments. Measurement of the age, size, and stellar contents of the clusters can test the hypothesis that super star clusters are young globular clusters. Together with our UV and optical data, NICMOS images will provide the SED of numerous super star clusters over a decade in wavelength. Our already-approved observations will allow us to estimate, by comparison with evolutionary synthesis models, the masses and ages of the clusters. The proposed IR data will be sensitive to the number of supergiants {1.6 micron} and O-stars {Paschen Alpha} in each of the clusters. The observations will provide an independent determination of the reddening, mass, and age of each cluster. We expect to see in the IR numerous clusters that are obscured in the UV and optical. These clusters may be the younger ones, which are still embedded in their molecular clouds. By measuring the mass, age, and size of a large number of clusters, we can actually obtain an evolutionary picture of these objects at different stages in their lives.

Effective tuning of electron charge and spin distribution in a dot-ring nanostructure at the ZnO interface

NASA Astrophysics Data System (ADS)

Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk

2018-05-01

Electronic states and the Aharonov-Bohm effect in ZnO quantum dot-ring nanostructures containing few interacting electrons reveal several unique features. We have shown here that in contrast to the dot-rings made of conventional semiconductors, such as InAs or GaAs, the dot-rings in ZnO heterojunctions demonstrate several unique characteristics due to the unusual properties of quantum dots and rings in ZnO. In particular the energy spectra of the ZnO dot-ring and the Aharnov-Bohm oscillations are strongly dependant on the electron number in the dot or in the ring. Therefore even small changes of the confinement potential, sizes of the dot-ring or the magnetic field can drastically change the energy spectra and the behavior of Aharonov-Bohm oscillations in the system. Due to this interesting phenomena it is possible to effectively control with high accuracy the electron charge and spin distribution inside the dot-ring structure. This controlling can be achieved either by changing the magnetic field or the confinement potentials.

High temperature seal compositions and methods of using same

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

Solberg, Scott Eugene

The disclosure relates to sealant compositions for forming hermetic seals, methods of use, and hermetically sealed products. The sealant compositions comprise a first inorganic oxide chosen from at least one of MgSiO.sub.3, MgO, MgTiO.sub.3, CaO, and CaSiO.sub.3, a second inorganic oxide chosen from SiO.sub.2, at least one solvent, and optionally at least one organic resin binder.

Some developments on ceramic-to-metal and glass-ceramics-to-metal seals and related studies

NASA Astrophysics Data System (ADS)

Kothiyal, G. P.; Goswami, M.; Shrikhande, V. K.

2008-05-01

Seals and coatings based on ceramics and glass-ceramics find numerous applications in different disciplines of science and technology including space, accelerators, nuclear energy, chemical industry. Ceramic-to-metal (CM) seals based on conventional design (using brazing alloys) and glass-ceramics have been prepared. While Ag-Cu brazing alloy has been used in conventional CM seal, we have employed lithium zinc silicate (LZS) and lithium aluminum silicate (LAS) glass-ceramics for glass-ceramics-to-metal (GCM) seals. LZS glass-ceramics based on two different compositions; (a) LZSL composition (wt.%)- Li2O: 12.65, ZnO: 1.85, SiO2: 74.4, Al2O3: 3.8, K2O: 2.95, P2O5: 3.15, and B2O3: 1.2 (low ZnO) and (b) LZSH composition (wt.%)- Li2O: 8.9, ZnO: 24.03, SiO2: 53.7, Na2O: 5.42, P2O5: 2.95, and B2O3: 5.0 (high ZnO) were prepared with desired sealing characteristics for matched type seals. In addition, (wt.%) 12.6Li2O-71.7SiO2-5.1Al2O3-4.9K2O-3.2B2O3-2.5P2O5 (LAS-GC) was investigated for compressive type of seal. LZS glass-ceramics-to-Cu as well as SS-321 seals were found to withstand a vacuum of 10-6 Torr with leak rate 10-9 Torr. 1/s and LAS GC-to-SS304 seal showed high pressure endurance of 12000psi. In order to understand the mechanism of sealing, glass-ceramics-to-metal interface study has also been carried out.

The plasmasheet H+ and O+ contribution on the storm time ring current

NASA Astrophysics Data System (ADS)

Mouikis, C.; Bingham, S.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

2015-12-01

The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes and Cluster observations to determine the contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. Using the Volland-Stern model with a dipole magnetic field together with the identification of the observed energy cutoffs in the particle spectra, we specify the pressure contributed by H+ and O+ populations that are on open drift paths vs. the pressure contributed by the trapped populations, for different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L~2 and their pressure compares to the local magnetic field pressure as deep as L~3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current.

Glass-ceramic composition for hermetic seals

DOEpatents

Ballard, Jr., Clifford P.

1979-01-01

The invention relates to a glass-ceramic composition having a high fracture strength adaptable for hermetically sealing to chromium bearing iron or nickel base alloys at temperatures of between about 950.degree. C to about 1100.degree. C to form a hermetically sealed insulator body, comprising from about 55 to about 65 weight percent SiO.sub.2, from about 0 to about 5 weight percent Al.sub.2 O.sub.3, from about 6 to about 11 weight % Li.sub.2 O, from about 25 to about 32 weight percent BaO, from about 0.5 to about 1.0 weight percent CoO and from about 1.5 to about 3.5 weight percent P.sub.2 O.sub.5.

Physical stability, microstructure and micro-rheological properties of water-in-oil-in-water (W/O/W) emulsions stabilized by porcine gelatin.

PubMed

Zhu, Qiaomei; Qiu, Shuang; Zhang, Hongwei; Cheng, Yongqiang; Yin, Lijun

2018-07-01

Water-in-oil-in-water (W/O/W) emulsions could be utilized for fat-reduced food formulation and delivery of bioactive nutrients. However, due to thermodynamic instability, it is difficult to prepare stable double emulsions. The purpose of this study was to improve the stability of W/O/W double emulsions containing 2.0 M MgCl 2 by adding porcine gelatin in the inner water phase. The impact of gelatin on the physical stability, microstructure and micro-rheological properties of W/O/W emulsions was investigated. It was found that, when the concentration of porcine gelatin exceeded 4.0 wt%, the stability of emulsions was improved, due to increased viscoelasticity of emulsion droplets. When MgCl 2 concentration increased to 2.0 M, the particle size of emulsions increased, due to the osmotic pressure gradient, and the presence of gelatin further increased the droplet size. Confocal microscopy results showed that the presence of gelatin could improve the stability of W/O/W emulsions against coalescence。. Copyright © 2018. Published by Elsevier Ltd.

Development of circumferential seal for helicopter transmissions: Results of bench and flight tests

NASA Technical Reports Server (NTRS)

Strom, T. N.; Ludwig, L. P.

1975-01-01

A modified circumferential segmented ring seal was designed for direct replacement of a helicopter transmission elastomeric lip seal operating on a shaft diameter of 13.91 centimeters (5.481 in.) at sliding velocities to 52.48 m/sec (10 330 ft/min). The modifications involved the garter spring tension, shaft roundness, seal housing flatness, and pumping grooves to inhibit leakage. Operation of the seals in bench tests under simulated helicopter transmission conditions revealed that the seal leakage rate was within acceptable limits and that the wear rate was negligible. The low leakage and wear rates were confirmed in flight tests of 600 and 175 hours (sliding speed, 48.11 m/sec (9470 ft/min)). An additional 200 hours of air worthiness qualification testing (aircraft tie down) demonstrated that the seal can operate at the advanced sliding conditions of 52.48 m/sec (10 330 ft/min).

A 300-year Vietnam hydroclimate and ENSO variability record reconstructed from tree ring δ18O

NASA Astrophysics Data System (ADS)

Sano, Masaki; Xu, Chenxi; Nakatsuka, Takeshi

2012-06-01

A tree ring δ18O chronology is developed for the past 300 years (1705-2004) using 6 cypress trees from northern Vietnam to reconstruct long-term hydroclimatic variations in the summer monsoon season. To the best of our knowledge, this is the first well-replicated tree ringδ18O chronology from Southeast Asia, as well as the longest yet produced. Response analyses reveal that tree ring δ18O is significantly correlated with temperature, precipitation, and the Palmer Drought Severity Index (PDSI) during the period May-October, with highest correlation to the PDSI. Our δ18O chronology accounts for 44% of the PDSI variance, and is in good agreement with a 52-year tree ringδ18O chronology from northern Laos (r = 0.77), indicating that regional hydroclimatic signals are well recorded in the δ18O data. Spatial correlation analyses with global sea surface temperatures suggest that the tropical Pacific plays an important role in modulating hydroclimate over the study region. Further, the δ18O chronology correlates significantly with El Niño-Southern Oscillation (ENSO)-related indices, and is therefore used to reconstruct the annual Multivariate ENSO Index. Because previously published ENSO reconstructions are based mainly on proxy records originating from North America and/or the tropical Pacific, the future development of a tree ringδ18O network from mainland Southeast Asia could lead to an independent and more robust reconstruction of ENSO variability.

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: A comparative study of photo catalysis on acid red 88

NASA Astrophysics Data System (ADS)

Balachandran, K.; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P.

2014-07-01

A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m2/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4 h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88.

Development and fabrication of insulator seals for thermionic diodes

NASA Technical Reports Server (NTRS)

Poirier, V. L.

1972-01-01

Eight different types of cermet seals for thermionic diodes were investigated: (1) 1 micron Al2O3 with Nb spheres; (2) 200 A Al2O3 with Nb spheres; (3) 1 micron Al2O3 with Nb 1% Zr spheres; (4) 200 A Al2O3 with Nb 1% Zr spheres; (5) Pure Y2O3 with Nb 1% Zr spheres; (6) Y2O3 3% ZrO2 with Nb 1% Zr spheres; (7) Y2O3 10% ZrO2 with Nb 1% Zr spheres; and (8) ZrO2 12% Y2O3 with Nb 1% Zr spheres. Investigations were made to determine the most favorable fabrication techniques and the effect of the bonding cycle, (length of bonding time and shutdown sequences). The analysis of the seals included tensile test, vacuum test, electrical test and metallurgical examination. At the conclusion of the development phase, 36 seals were fabricated for delivery for evaluation.

Photocatalytic Activity of W-Doped TiO2 Nanofibers for Methylene Blue Dye Degradation.

PubMed

Song, Yo-Seung; Cho, Nam-Ihn; Lee, Myung-Hyun; Kim, Bae-Yeon; Lee, Deuk Yong

2016-02-01

Photocatalytic degradation of methylene blue (MB) in water was examined using W-doped TiO2 nanofibers prepared by a sol-gel derived electrospinning and subsequent calcination for 4 h at 550 degrees C. Different concentrations of W dopant in the range of 0 to 8 mol% were synthesized to evaluate the effect of W concentration on the photocatalytic activity of TiO2. XRD results indicated that the undoped TiO2 is composed of anatase and rutile phases. The rutile phase was transformed to anatase phase completely with the W doping. Among W-TiO2 catalysts, the 2 mol% W-TiO2 catalyst showed the highest MB degradation rate. The degradation kinetic constant increased from 1.04 x 10(-3) min(-1) to 3.54 x 10(-3) min(-1) with the increase of W doping from 0 to 2 mol%, but decreased down to 1.77 x 10(-3) min(-1) when the W content was 8 mol%. It can be concluded that the degradation of MB under UV radiation was more efficient with W-TiO2 catalysts than with pure TiO2-

Y0.08Sr0.88TiO3-CeO2 composite as a diffusion barrier layer for stainless-steel supported solid oxide fuel cell

NASA Astrophysics Data System (ADS)

Kim, Kun Joong; Kim, Sun Jae; Choi, Gyeong Man

2016-03-01

A new diffusion barrier layer (DBL) is proposed for solid oxide fuel cells (SOFCs) supported on stainless-steel where DBL prevents inter-diffusion of atoms between anode and stainless steel (STS) support during fabrication and operation of STS-supported SOFCs. Half cells consisting of dense yttria-stabilized zirconia (YSZ) electrolyte, porous Ni-YSZ anode layer, and ferritic STS support, with or without Y0.08Sr0.88TiO3-CeO2 (YST-CeO2) composite DBL, are prepared by tape casting and co-firing at 1250 and 1350 °C, respectively, in reducing (H2) atmosphere. The porous YST-CeO2 layer (t ∼ 60 μm) blocks inter-diffusion of Fe and Ni, and captures the evaporated Cr during cell fabrication (1350 °C). The cell with DBL and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode achieved a maximum power density of ∼220 mW cm-2 which is stable at 700 °C. In order to further improve the power performance, Ni coarsening in anode during co-firing must be prevented or alternative anode which is resistive to coarsening is suggested. This study demonstrates that the new YST-CeO2 layer is a promising as a DBL for stainless-steel-supported SOFCs fabricated with co-firing process.

Fractal modeling of fluidic leakage through metal sealing surfaces

NASA Astrophysics Data System (ADS)

Zhang, Qiang; Chen, Xiaoqian; Huang, Yiyong; Chen, Yong

2018-04-01

This paper investigates the fluidic leak rate through metal sealing surfaces by developing fractal models for the contact process and leakage process. An improved model is established to describe the seal-contact interface of two metal rough surface. The contact model divides the deformed regions by classifying the asperities of different characteristic lengths into the elastic, elastic-plastic and plastic regimes. Using the improved contact model, the leakage channel under the contact surface is mathematically modeled based on the fractal theory. The leakage model obtains the leak rate using the fluid transport theory in porous media, considering that the pores-forming percolation channels can be treated as a combination of filled tortuous capillaries. The effects of fractal structure, surface material and gasket size on the contact process and leakage process are analyzed through numerical simulations for sealed ring gaskets.

Development of w/o microemulsion for transdermal delivery of iodide ions.

PubMed

Lou, Hao; Qiu, Ni; Crill, Catherine; Helms, Richard; Almoazen, Hassan

2013-03-01

The objective of this study was to develop a water-in-oil (w/o) microemulsion which can be utilized as a transdermal delivery for iodide ions. Several w/o microemulsion formulations were prepared utilizing Span 20, ethanol, Capryol 90®, and water. The selected formulations had 5%, 10%, 15%, 20%, and a maximum of 23% w/w water content. Potassium iodide (KI) was incorporated in all formulations at 5% w/v. Physicochemical characterizations were conducted to evaluate the structure and stability. These studies included: mean droplet size, pH, viscosity, conductivity, and chemical stability tests. In vitro human skin permeation studies were conducted to evaluate the diffusion of the iodide ion through human skin. The w/o microemulsion formulations were stable and compatible with iodide ions with water content ranging from 5% to 23% w/w. The addition of KI influenced the physicochemical properties of microemulsion as compared to blank microemulsion formulations. In vitro human skin permeation studies indicated that selected formulations improved iodide ion diffusion significantly as compared to control (KI solution; P value<0.05). Iodide ions were entrapped within the aqueous core of w/o microemulsion. Span 20, ethanol and Capryol 90 protected the iodide ions against oxidation and formed a stable microemulsion. It is worth to note that according to Hofmeister series, iodide ions tend to lower the interfacial tension between water and oil and consequently enhance overall stability. This work illustrates that microemulsion system can be utilized as a vehicle for the transdermal administration of iodide.

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: a comparative study of photo catalysis on acid red 88.

PubMed

Balachandran, K; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P

2014-07-15

A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m(2)/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88. Copyright © 2014 Elsevier B.V. All rights reserved.

Seals and Sealing Techniques

NASA Technical Reports Server (NTRS)

1972-01-01

Developments by the aerospace industry in seals and sealing techniques are announced for possible use in other areas. The announcements presented are grouped as: sealing techniques for cryogenic fluids, high pressure applications, and modification for improved performance.

Tribological evaluation of an Al2O3-SiO2 ceramic fiber candidate for high temperature sliding seals

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Steinetz, Bruce

1992-01-01

A test program to determine the relative sliding durability of an alumina-silica candidate ceramic fiber for high temperature sliding seal applications as described. This work represents the first reporting of the sliding durability of this material system. Pin-on-disk tests were used to evaluate the potential seal material by sliding a tow or bundle of the candidate ceramic fiber against a superalloy test disk. Friction was measured during the tests and fiber wear, indicated by the extent of fibers broken in the tow or bundle, was measured at the end of each test. Test variables studied included ambient temperatures from 25 C to 900 C, loads from 1.3 to 21.2 Newtons, and sliding velocities from 0.025 to 0.25 m/sec. In addition, the effects of fiber diameter, elastic modulus, and a pretest fiber heat treatment on friction and wear were measured. In most cases, wear increased with temperature. Friction ranged from about 0.36 at 500 C and low velocity (0.025 m/s) to over 1.1 at 900 C and high velocity (0.25 m/s). The pretest fiber heat treatment, which caused significant durability reductions for alumina-boria-silica ceramic fibers tested previously, had little effect on the alumina-silica fibers tested here. These results indicate that the alumina-silica (Al2O3-SiO2) fiber is a good candidate material system for high temperature sliding seal applications.

Tribological evaluation of an Al2O3-SiO2 ceramic fiber candidate for high temperature sliding seals

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Steinetz, Bruce

1994-01-01

A test program to determine the relative sliding durability of an alumina-silica candidate ceramic fiber for high temperature sliding seal applications is described. Pin-on-disk tests were used to evaluate the potential seal material by sliding a tow or bundle of the candidate ceramic fiber against a superalloy test disk. Friction was measured during the tests and fiber wear, indicated by the extent of fibers broken in the tow or bundle, was measured at the end of each test. Test variables studied included ambient temperatures from 25 to 900 C, loads from 1.3 to 21.2 N, and sliding velocities from 0.025 to 0.25 m/sec. In addition, the effects of fiber diameter and elastic modulus on friction and wear were measured. Thin gold films deposited on the superalloy disk surface were evaluated in an effort to reduce friction and wear of the fibers. In most cases, wear increased with test temperature. Friction ranged from 0.36 at 500 C and low velocity (0.025 m/sec) to over 1.1 at 900 C and high velocity (0.25 m/sec). The gold films resulted in satisfactory lubrication of the fibers at 25 C. At elevated temperatures diffusion of substrate elements degraded the films. These results indicate that the alumina-silica (Al2O3-SiO2) fiber is a good candidate material system for high temperature sliding seal applications. More work is needed to reduce friction.

Tribological evaluation of an Al2O3-SiO2 ceramic fiber candidate for high-temperature sliding seals

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

Dellacorte, C.; Steinetz, B.

A test program to determine the relative sliding durability of an alumina-silica candidate ceramic fiber for high temperature sliding seal applications as described. This work represents the first reporting of the sliding durability of this material system. Pin-on-disk tests were used to evaluate the potential seal material by sliding a tow or bundle of the candidate ceramic fiber against a superalloy test disk. Friction was measured during the tests and fiber wear, indicated by the extent of fibers broken in the tow or bundle, was measured at the end of each test. Test variables studied included ambient temperatures from 25more » C to 900 C, loads from 1.3 to 21.2 Newtons, and sliding velocities from 0.025 to 0.25 m/sec. In addition, the effects of fiber diameter, elastic modulus, and a pretest fiber heat treatment on friction and wear were measured. In most cases, wear increased with temperature. Friction ranged from about 0.36 at 500 C and low velocity (0.025 m/s) to over 1.1 at 900 C and high velocity (0.25 m/s). The pretest fiber heat treatment, which caused significant durability reductions for alumina-boria-silica ceramic fibers tested previously, had little effect on the alumina-silica fibers tested here. These results indicate that the alumina-silica (Al2O3-SiO2) fiber is a good candidate material system for high temperature sliding seal applications.« less

Numerical analysis of the non-contacting gas face seals

NASA Astrophysics Data System (ADS)

Blasiak, S.

2017-08-01

The non-contacting gas face seals are used in high-performance devices where the main requirements are safety and reliability. Compliance with these requirements is made possible by careful research and analysis of physical processes related to, inter alia, fluid flow through the radial gap and ring oscillations susceptible to being housed in the enclosure under the influence of rotor kinematic forces. Elaborating and developing mathematical models describing these phenomena allows for more and more accurate analysis results. The paper presents results of studies on stationary ring oscillations made of different types of materials. The presented results of the research allow to determine which of the materials used causes the greatest amplitude of the vibration of the system fluid film-working rings.

Sampling strategy and climatic implication of tree-ring cellulose oxygen isotopes of Hippophae tibetana and Abies georgei on the southeastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xu, Chenxi; Zhu, Haifeng; Nakatsuka, Takeshi; Sano, Masaki; Li, Zhen; Shi, Feng; Liang, Eryuan; Guo, Zhengtang

2017-05-01

The tree-ring cellulose oxygen isotopes (δ18O) for four trees of Hippophae tibetana and four trees of Abies georgei growing in different locations around the terminal moraine in Xincuo from 1951 to 2010 were measured to explore its potential for reconstructing climatic variations in the southeastern Tibetan Plateau. The mean and standard deviation of tree-ring δ18O at different heights do not have significant differences, and there are no significant differences in the mean and standard deviation of tree-ring δ18O between trees near the brook and trees at the top of moraine, indicating that we can collect samples for tree-ring δ18O analysis regardless of sampling heights and that the micro-environment does not affect tree-ring δ18O significantly. The mean inter-series correlations of cellulose δ18O for A. georgei/H. tibetana are 0.84/0.93, and the correlation between δ18O for A. georgei and H. tibetana is 0.92. The good coherence between inter-tree and inter-species cellulose δ18O demonstrates the possibility of using different species to develop a long chronology. Correlation analysis between tree-ring δ18O and climate parameters revealed that δ18O for A. georgei/H. tibetana had negative correlations (r = -0.62/r = -0.69) with relative humidity in July-August, and spatial correlation revealed that δ18O for A. georgei/H. tibetana reflected the regional Standardized Precipitation Evapotranspiration Index (29°-32° N, 88°-98° E). In addition, tree-ring δ18O in Xincuo has a significant correlation with tree-ring δ18O in Bhutan. The results indicate that cellulose δ18O for A. georgei and H. tibetana in Xincuo is a good proxy for the regional hydroclimate.

The Role of Ionospheric O+ in Forming the Storm-time Ring Current

NASA Astrophysics Data System (ADS)

Kistler, L. M.; Mouikis, C.; Menz, A.; Bingham, S.

2017-12-01

During storm times, the particle pressure that creates the storm-time ring current in the inner magnetosphere can be dominated by O+. This is surprising, as the immediate source for the ring current is the nightside plasma sheet, and O+ is usually not the dominant species in the plasma sheet. In this talk we examine the many factors that lead to this result. The O+ outflow is enhanced during geomagnetically active times. The transport paths of O+ and H+ are different, such that the O+ that reaches the near-earth plasma sheet is more energetic than H+. The source spectrum in the near-earth plasma sheet can be harder for O+ than for H+, perhaps due to substorm injections, so that the more energetic plasma has a higher O+/H+ ratio. And finally the plasma sheet O+ can be more abundant towards the beginning of the storm, when the convection is largest, so the enhanced O+ is brought the deepest into the inner magnetosphere. We will discuss the interrelationships between these different effects as well as the ways in which O+ itself may influence the system.

Near Infrared Photometry of the Jovian Ring and Adrastea

NASA Astrophysics Data System (ADS)

Meier, Roland; Smith, Bradford A.; Owen, Tobias C.; Becklin, E. E.; Terrile, Richard J.

1999-10-01

The near IR spectral reflectance of the Jupiter dust ring is poorly known because of problems with scattered light from the planet. Here we report colors for the jovian ring and one of the two ring satellites, Adrastea, using observations from the near-IR camera NICMOS on the Hubble Space Telescope. Near the time when the Earth crossed the jovian ring plane in the fall of 1997, we recorded broad-band images at ˜1.1 (F110W), ˜1.6 (F160W), and ˜2.05 μm (F205W) and derived a single-pass, in radial direction measured ring brightness of 19.19±0.07, 18.76±0.06, and 18.49±0.04 mag linear arcsec -1, respectively. These single-pass radial ring brightnesses were derived from the observable part of the ring at a projected distance of >1.2 RJ using a model to remove projection effects. The corresponding apparent magnitudes for Adrastea are 18.30±0.10 (F110W), 17.73±0.09 (F160W), and 17.57±0.07 mag (F205W), obtained at a phase angle of φ=11.3°. The relative spectral reflectance of the ring and that of Adrastea turn out to be nearly identical, slightly reddish with a slope of about 15-20% between 1 and 2 μm. No evidence for transient ice crystals to be present in the main ring is seen. Our data are also in reasonable agreement with earlier ground-based measurements by Neugebauer et al. (1981), if we take their relatively large errors into account. The similarities of the colors of all inner satellites, including Io, are striking. The measured ring color provides evidence that the backscattered light from the ring is due to grains with mean particle sizes in excess of several micrometers. We were also able to infer a spatial particle distribution for the main ring. Its radial surface-density profile peaks sharply near the outer edge of the ring at the orbit of Adrastea, suggesting a strong dynamical relationship between the satellite and the ring particles. Our radial profile of the main ring is in excellent agreement with the results from Voyager images in

Measurement of behavior of secondary sealing areas of rotary engine apex seals - Two-piece nonsplit and three-piece slanted horizontal split types

NASA Astrophysics Data System (ADS)

Matsuura, Kenji; Terasaki, Kazuo; Yamane, Katsuki

1992-12-01

Behavior measurements have been made with two displacement sensors and an underseal pressure sensor, using an overhanging eccentric shaft-type single-rotor research engine equipped with a packaged multichannel slip ring. The two-piece seal was tilted to the leading and trailing sides of a seal slot during its travel along the rotor housing surface and vibrated on the top end of the leading side of the slot as a fulcrum after the shift from the trailing to the leading side of the slot after the minor axis on the spark plug side. As for the three-piece seal, its top part was also tilted in all operating conditions, although its bottom part made effective area contact with the side of the slot under light load conditions up to medium engine speeds. The working chamber pressure was induced in the underseal in the same manner as with the two-piece type.

Rapid sealing and cutting of porcine blood vessels, ex vivo, using a high-power, 1470-nm diode laser.

PubMed

Giglio, Nicholas C; Hutchens, Thomas C; Perkins, William C; Latimer, Cassandra; Ward, Arlen; Nau, William H; Fried, Nathaniel M

2014-03-01

Suture ligation with subsequent cutting of blood vessels to maintain hemostasis during surgery is time consuming and skill intensive. Energy-based electrosurgical and ultrasonic devices are often used to replace sutures and mechanical clips to provide rapid hemostasis and decrease surgery time. Some of these devices may create undesirably large collateral zones of thermal damage and tissue necrosis, or require separate mechanical blades for cutting. Infrared lasers are currently being explored as alternative energy sources for vessel sealing applications. In a previous study, a 1470-nm laser was used to seal vessels 1 to 6 mm in diameter in 5 s, yielding burst pressures of ∼500  mmHg. The purpose of this study was to provide vessel sealing times comparable with current energy-based devices, incorporate transection of sealed vessels, and demonstrate high vessel burst pressures to provide a safety margin for future clinical use. A 110-W, 1470-nm laser beam was transmitted through a fiber and beam shaping optics, producing a 90-W linear beam 3.0 by 9.5 mm for sealing (400  W/cm2), and 1.1 by 9.6 mm for cutting (1080  W/cm2). A two-step process sealed and then transected ex vivo porcine renal vessels (1.5 to 8.5 mm diameter) in a bench top setup. Seal and cut times were 1.0 s each. A burst pressure system measured seal strength, and histologic measurements of lateral thermal spread were also recorded. All blood vessels tested (n=55 seal samples) were sealed and cut, with total irradiation times of 2.0 s and mean burst pressures of 1305±783  mmHg. Additional unburst vessels were processed for histological analysis, showing a lateral thermal spread of 0.94±0.48  mm (n=14 seal samples). This study demonstrated that an optical-based system is capable of precisely sealing and cutting a wide range of porcine renal vessel sizes and, with further development, may provide an alternative to radiofrequency- and ultrasonic-based vessel sealing devices.

Cellulose Nanofibril Based-Aerogel Microreactors: A High Efficiency and Easy Recoverable W/O/W Membrane Separation System

PubMed Central

Zhang, Fang; Ren, Hao; Dou, Jing; Tong, Guolin; Deng, Yulin

2017-01-01

Hereby we report a novel cellulose nanofirbril aerogel-based W/O/W microreactor system that can be used for fast and high efficient molecule or ions extraction and separation. The ultra-light cellulose nanofibril based aerogel microspheres with high porous structure and water storage capacity were prepared. The aerogel microspheres that were saturated with stripping solution were dispersed in an oil phase to form a stable water-in-oil (W/O) suspension. This suspension was then dispersed in large amount of external waste water to form W/O/W microreactor system. Similar to a conventional emulsion liquid membrane (ELM), the molecules or ions in external water can quickly transport to the internal water phase. However, the microreactor is also significantly different from traditional ELM: the water saturated nanocellulose cellulose aerogel microspheres can be easily removed by filtration or centrifugation after extraction reaction. The condensed materials in the filtrated aerogel particles can be squeezed and washed out and aerogel microspheres can be reused. This novel process overcomes the key barrier step of demulsification in traditional ELM process. Our experimental indicates the novel microreactor was able to extract 93% phenol and 82% Cu2+ from external water phase in a few minutes, suggesting its great potential for industrial applications. PMID:28059153

Cellulose Nanofibril Based-Aerogel Microreactors: A High Efficiency and Easy Recoverable W/O/W Membrane Separation System

NASA Astrophysics Data System (ADS)

Zhang, Fang; Ren, Hao; Dou, Jing; Tong, Guolin; Deng, Yulin

2017-01-01

Hereby we report a novel cellulose nanofirbril aerogel-based W/O/W microreactor system that can be used for fast and high efficient molecule or ions extraction and separation. The ultra-light cellulose nanofibril based aerogel microspheres with high porous structure and water storage capacity were prepared. The aerogel microspheres that were saturated with stripping solution were dispersed in an oil phase to form a stable water-in-oil (W/O) suspension. This suspension was then dispersed in large amount of external waste water to form W/O/W microreactor system. Similar to a conventional emulsion liquid membrane (ELM), the molecules or ions in external water can quickly transport to the internal water phase. However, the microreactor is also significantly different from traditional ELM: the water saturated nanocellulose cellulose aerogel microspheres can be easily removed by filtration or centrifugation after extraction reaction. The condensed materials in the filtrated aerogel particles can be squeezed and washed out and aerogel microspheres can be reused. This novel process overcomes the key barrier step of demulsification in traditional ELM process. Our experimental indicates the novel microreactor was able to extract 93% phenol and 82% Cu2+ from external water phase in a few minutes, suggesting its great potential for industrial applications.

Thermal effects in two-phase flow through face seals. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Basu, Prithwish

1988-01-01

When liquid is sealed at high temperature, it flashes inside the seal due to pressure drop and/or viscous heat dissipation. Two-phase seals generally exhibit more erratic behavior than their single phase counterparts. Thermal effects, which are often neglected in single phase seal analyses, play an important role in determining seal behavior under two-phase operation. It is necessary to consider the heat generation due to viscous shear, conduction into the seal rings and convection with the leakage flow. Analytical models developed work reasonably well at the two extremes - for low leakage rates when convection is neglected and for higher leakage rates when conduction is neglected. A preliminary model, known as the Film Coefficient Model, is presented which considers conduction and convection both, and allows continuous boiling over an extended region unlike the previous low-leakage rate model which neglects convection and always forces a discrete boiling interface. Another simplified, semi-analytical model, based on the assumption of isothermal conditions along the seal interafce, has been developed for low leakage rates. The Film Coefficient Model may be used for more accurate and realistic description.

Method and apparatus for performing in-situ vacuum-assisted metal to glass sealing

DOEpatents

Kramer, D.P.; Massey, R.T.

1985-07-18

A method and apparatus for assembling and fusing glass to metal in a glass-metal electrical component is disclosed. The component includes a metallic shell formed with upper and lower cylindrical recesses connected together by longitudinal passages, a pair of metal rings and plural metal pins assembled to define electrical feed-throughs. The component parts are assembled on a fixture having a sleeve-like projection and a central mounting projection establishing concentric nesting surfaces to which the metal rings are slip-fitted in concentric alignment with each other spaced from sidewalls of the lower recess. The pins are in electrical contact with the metal rings. A glass pre-form is seated within the upper recess. The assembled structure is heated to a temperature sufficient to melt the glass pre-form which flows under gravity through the passages into the lower recess to provide an insulative seal between the metal parts. The gravity flow of glass is assisted by applying vacuum to the lower recess, ensuring that all spaces between the metal parts are filled with sealing glass without formation of bubbles.

Method and apparatus for performing in-situ vacuum-assisted metal to glass sealing

DOEpatents

Kramer, Daniel P.; Massey, Richard T.

1986-01-01

A method and apparatus for assembling and fusing glass to metal in a glass-metal electrical component is disclosed. The component includes a metallic shell formed with upper and lower cylindrical recesses connected together by longitudinal passages, a pair of metal rings and plural metal pins assembled to define electrical feed-throughs. The component parts are assembled on a fixture having a sleeve-like projection and a central mounting projection establishing concentric nesting surfaces to which the metal rings are slip-fitted in concentric alignment with each other spaced from sidewalls of the lower recess. The pins are in electrical contact with the metal rings. A glass pre-form is seated within the upper recess. The assembled structure is heated to a temperature sufficient to melt the glass pre-form which flows under gravity through the passages into the lower recess to provide an insulative seal between the metal parts. The gravity flow of glass is assisted by applying vacuum to the lower recess, ensuring that all spaces between the metal parts are filled with sealing glass without formation of bubbles.

An Experimental Investigation of Leak Rate Performance of a Subscale Candidate Elastomer Docking Space Seal

NASA Technical Reports Server (NTRS)

Garafolo, Nicholas G.; Daniels, Christopher C.

2011-01-01

A novel docking seal was developed for the main interface seal of NASA s Low Impact Docking System (LIDS). This interface seal was designed to maintain acceptable leak rates while being exposed to the harsh environmental conditions of outer space. In this experimental evaluation, a candidate docking seal assembly called Engineering Development Unit (EDU58) was characterized and evaluated against the Constellation Project leak rate requirement. The EDU58 candidate seal assembly was manufactured from silicone elastomer S0383-70 vacuum molded in a metal retainer ring. Four seal designs were considered with unique characteristic heights. The leak rate performance was characterized through a mass point leak rate method by monitoring gas properties within an internal control volume. The leakage performance of the seals were described herein at representative docking temperatures of -50, +23, and +50 C for all four seal designs. Leak performance was also characterized at 100, 74, and 48 percent of full closure. For all conditions considered, the candidate seal assemblies met the Constellation Project leak rate requirement.

Organochlorine residues in harp seal (Phagophilus groenlandicus) tissues, Gulf of St. Lawrence, 1971, 1973.

PubMed

Rosewell, K T; Muir, D C; Baker, B E

1979-03-01

Levels of p,p'-DDT, p,p'-TDE, p,p'-DDE, dieldrin, polychlorinated biphenyls (PCBs), and HCB were determined in certain tissues of 31 harp seals (P hagophilus groenlandicus) taken from the Gulf of St. Lawrence during 1971 and 1973. The seals ranged in age from less than two weeks to 18 years. Mean concentrations of PCBs and sigma DDT in the various tissues were about the same sigma DDT levels were 1.64--9.88 ppm in adult seal blubber and 1.08--3.73 ppm in seal pup blubber. Organochlorine levels in harp seal samples taken in 1973 were similar to those reported by other workers for samples collected in the Gulf of St. Lawrence during 1967-71.

Utilisation of water-in-oil-water (W1/O/W2) double emulsion in a set-type yogurt model for the delivery of probiotic Lactobacillus paracasei.

PubMed

El Kadri, Hani; Lalou, Sofia; Mantzouridou, FaniTh; Gkatzionis, Konstantinos

2018-05-01

W 1 /O/W 2 emulsion in set-type yogurt has the potential to segregate probiotics in order to avoid interference with the starter culture as well as protection against harsh processing and digestion conditions. Lactobacillus paracasei subsp. paracasei DC 412 probiotic cells in milk-based W 1 /O/W 2 emulsions were incorporated in yogurt, in addition to starter cultures Lactobacillus bulgaricus and Streptococcus thermophilus, and the effect on the fermentation, bacterial growth kinetics, physicochemical properties, and structural characteristics was investigated. Stability of W 1 /O/W 2 was monitored with optical microscopy and cryo-SEM and localisation of encapsulated L. paracasei in yogurt was monitored using fluorescent microscopy. During fermentation, starter culture was not affected by introduction of L. paracasei and/or W 1 /O/W 2 emulsion. The viability of L. paracasei encapsulated in W 1 /O/W 2 emulsion was enhanced during storage and after exposure to simulated gastrointestinal conditions. L. paracasei remained within the inner W 1 phase till the end of the storage period (28 days at 4 °C). Moreover, W 1 /O/W 2 emulsion altered physicochemical and textural properties; however, these were within acceptable range. These results demonstrate the capability of W 1 /O/W 2 emulsion to be utilised for probiotic fortification of yogurt to increase functionality without interfering with starter culture and fermentation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Lattice design for the CEPC double ring scheme

NASA Astrophysics Data System (ADS)

Wang, Yiwei; Su, Feng; Bai, Sha; Zhang, Yuan; Bian, Tianjian; Wang, Dou; Yu, Chenghui; Gao, Jie

2018-01-01

A future Circular Electron Positron Collider (CEPC) has been proposed by China with the main goal of studying the Higgs boson. Its baseline design, chosen on the basis of its performance, is a double ring scheme; an alternative design is a partial double ring scheme which reduces the budget while maintaining an adequate performance. This paper will present the collider ring lattice design for the double ring scheme. The CEPC will also work as a W and a Z factory. For the W and Z modes, except in the RF region, compatible lattices were obtained by scaling down the magnet strength with energy.

Separation Properties of Wastewater Containing O/W Emulsion Using Ceramic Microfiltration/Ultrafiltration (MF/UF) Membranes

PubMed Central

Nakamura, Kazuho; Matsumoto, Kanji

2013-01-01

Washing systems using water soluble detergent are used in electrical and mechanical industries and the wastewater containing O/W emulsion are discharged from these systems. Membrane filtration has large potential for the efficient separation of O/W emulsion for reuses of treated water and detergent. The separation properties of O/W emulsions by cross-flow microfiltration and ultrafiltration were studied with ceramic MF and UF membranes. The effects of pore size; applied pressure; cross-flow velocity; and detergent concentration on rejection of O/W emulsion and flux were systematically studied. At the condition achieving complete separation of O/W emulsion the pressure-independent flux was observed and this flux behavior was explained by gel-polarization model. The O/W emulsion tended to permeate through the membrane at the conditions of larger pore size; higher emulsion concentration; and higher pressure. The O/W emulsion could permeate the membrane pore structure by destruction or deformation. These results imply the stability of O/W emulsion in the gel-layer formed on membrane surface play an important role in the separation properties. The O/W emulsion was concentrated by batch cross-flow concentration filtration and the flux decline during the concentration filtration was explained by the gel- polarization model. PMID:24958621

Method of processing "BPS" glass ceramic and seals made therewith

DOEpatents

Reed, Scott T.; Stone, Ronald G.; McCollister, Howard L.; Wengert, deceased, Paul R.

1998-01-01

A glass ceramic composition, a glass ceramic-to-metal seal, and more specifically a hermetic glass ceramic-to-metal seal prepared by subjecting a glass composition comprising, by weight percent, SiO.sub.2 (65-80%), LiO.sub.2 (8-16%), Al.sub.2 O.sub.3 (2-8%), K.sub.2 O (1-8%), P.sub.2 O.sub.5 (1-5%), B.sub.2 O.sub.3 (0.5-7%), and ZnO (0-5%) to the following processing steps: 1) heating the glass composition in a belt furnace to a temperature sufficient to melt the glass and crystallize lithium phosphate, 2) holding at a temperature and for a time sufficient to create cristobalite nuclei, 3) cooling at a controlled rate and to a temperature to cause crystallization of lithium silicates and growth of cristobalite, and 4) still further cooling in stages to ambient temperature. This process produces a glass ceramic whose high coefficient of thermal expansion (up to 200.times.10.sup.-7 in/in/.degree.C.) permits the fabrication of glass ceramic-to-metal seals, and particularly hermetic glass ceramic seals to nickel-based and stainless steel alloys and copper.

Method of processing ``BPS`` glass ceramic and seals made therewith

DOEpatents

Reed, S.T.; Stone, R.G.; McCollister, H.L.; Wengert, P.R.

1998-10-13

A glass ceramic composition, a glass ceramic-to-metal seal, and more specifically a hermetic glass ceramic-to-metal seal prepared by subjecting a glass composition comprising, by weight percent, SiO{sub 2} (65--80%), LiO{sub 2} (8--16%), Al{sub 2}O{sub 3} (2--8%), K{sub 2}O (1--8%), P{sub 2}O{sub 5} (1--5%), B{sub 2}O{sub 3} (0.5--7%), and ZnO (0--5%) to the following processing steps: (1) heating the glass composition in a belt furnace to a temperature sufficient to melt the glass and crystallize lithium phosphate, (2) holding at a temperature and for a time sufficient to create cristobalite nuclei, (3) cooling at a controlled rate and to a temperature to cause crystallization of lithium silicates and growth of cristobalite, and (4) still further cooling in stages to ambient temperature. This process produces a glass ceramic whose high coefficient of thermal expansion (up to 200{times}10{sup {minus}7} in/in/C) permits the fabrication of glass ceramic-to-metal seals, and particularly hermetic glass ceramic seals to nickel-based and stainless steel alloys and copper. 5 figs.

Effect of epoxy resin sealing on corrosion resistance of arc spraying aluminium coating using cathode electrophoresis method

NASA Astrophysics Data System (ADS)

Pang, Xuming; Wang, Runqiu; Wei, Qian; Zhou, Jianxin

2018-01-01

Arc-sprayed Al coating was sealed with epoxy resin using the cathode electrophoresis method. The anti-corrosion performance of the coatings sealed with epoxy resin was studied by means of a 3.5 wt.% NaCl solution test at 40 °C. For comparison, the anti-corrosion performance of Al coating sealed with boiling water was also performed under the same conditions. The results show that epoxy resin with a thickness of about 20 microns can entirely cover open pores and decreases the surface roughness of the as-sprayed Al coating, and the epoxy resin even permeates into the gaps among lamellar splats from open pores. After corrosion, the thickness of the epoxy resin layer is unchanged and can still cover the as-sprayed Al coating entirely. However, the thickness of Al coating sealed with boiling water decreases from 100 to 40 microns, which indicates that the arc-sprayed Al coating has much better corrosion resistance than the Al coating sealed with boiling water. Meanwhile, the content of substituted benzene ring in the epoxy resin increases, but aromatic ring decreases according to the fourier transform infrared spectra, which will cause the rigidity of the epoxy resin to increase, but the toughness slightly decreases after corrosion.

Conformity of modified O-ring test and maximal pinch strength for cross tape application direction.

PubMed

Lee, Jung-Hoon; Choi, Hyun-Su

2018-06-01

Although cross tape has recently been used by clinicians for various musculoskeletal conditions, scientific studies on the direction of cross tape application are lacking. The present study aimed to investigate whether the direction of cross tape application affected the outcomes of the modified O-ring test and maximal pinch strength using a pinch gauge and the conformity between these 2 tests when cross tape was applied to the forearm muscles of individuals with no upper extremity pain and no restriction of joint range of motion.This study used a single-blinding crossover design. The subjects comprised 39 adults (16 men and 23 women). Cross tape was applied to the dominant hand so that the 4 rows were at an angle of 45° to the right or left of the direction of the flexor digitorum superficialis muscle fibers, and then the subjects underwent a modified O-ring test and a test of maximal pinch strength using a pinch gauge. Both tests were performed in both directions, and the order of the directions and tests was randomized. SPSS 18.0 was used for statistical analysis. Cohen's kappa coefficient was used to analyze the conformity of the results from the 2 tests. The statistical significance level was P < .05. A positive response in the modified O-ring test and maximal pinch strength were both affected by cross tape direction. The modified O-ring test and maximal pinch strength using pinch gauge results were in agreement (P < .00), and the kappa coefficient was significant at 1.00. The direction of cross tape application that produced a positive response in the modified O-ring test also produced greater maximal pinch strength. Thus, we propose that when applying cross tape to muscles, the direction of the 4 lines of the cross tape should be 45° relative to the direction of the muscle fibers, toward the side that produces a positive response in the modified O-ring test or produces the greatest maximal pinch strength using a pinch gauge.

Preparation of solid lipid nanoparticles from W/O/W emulsions: preliminary studies on insulin encapsulation.

PubMed

Gallarate, Marina; Trotta, Michele; Battaglia, Luigi; Chirio, Daniela

2009-08-01

A method to produce solid lipid nanoparticles (SLN) from W/O/W multiple emulsions was developed applying the solvent-in-water emulsion-diffusion technique. Insulin was chosen as hydrophilic peptide drug to be dissolved in the acidic inner aqueous phase of multiple emulsions and to be consequently carried in SLN. Several partially water-miscible solvents with low toxicity were screened in order to optimize emulsions and SLN composition, after assessing that insulin did not undergo any chemical modification in the presence of the different solvents and under the production process conditions. SLN of spherical shape and with mean diameters in the 600-1200 nm range were obtained by simple water dilution of the W/O/W emulsion. Best results, in terms of SLN mean diameter and encapsulation efficiencies, were obtained using glyceryl monostearate as lipid matrix, butyl lactate as a solvent, and soy lecithin and Pluronic F68 as surfactants. Encapsulation efficiencies up to 40% of the loaded amount were obtained, owing to the actual multiplicity of the system; the use of multiple emulsion-derived SLN can be considered a useful strategy to encapsulate a hydrophilic drug in a lipid matrix.

High thermal expansion, sealing glass

DOEpatents

Brow, Richard K.; Kovacic, Larry

1993-01-01

A glass composition for hermetically sealing to high thermal expansion materials such as aluminum alloys, stainless steels, copper, and copper/beryllium alloys, which includes between about 10 and about 25 mole percent Na.sub.2 O, between about 10 and about 25 mole percent K.sub.2 O, between about 5 and about 15 mole percent Al.sub.2 O.sub.3, between about 35 and about 50 mole percent P.sub.2 O.sub.5 and between about 5 and about 15 mole percent of one of PbO, BaO, and mixtures thereof. The composition, which may also include between 0 and about 5 mole percent Fe.sub.2 O.sub.3 and between 0 and about 10 mole percent B.sub.2 O.sub.3, has a thermal expansion coefficient in a range of between about 160 and 210.times.10-7/.degree.C. and a dissolution rate in a range of between about 2.times.10.sup.- 7 and 2.times.10.sup.-9 g/cm.sup.2 -min. This composition is suitable to hermetically seal to metallic electrical components which will be subjected to humid environments over an extended period of time.

Characterization of the faecal bacterial community of wild young South American (Arctocephalus australis) and Subantarctic fur seals (Arctocephalus tropicalis).

PubMed

Medeiros, Aline Weber; Giongo, Adriana; Valdez, Fernanda P; Blaese de Amorin, Derek; Tavares, Maurício; d'Azevedo, Pedro A; Franco, Ana Claudia; Frazzon, Jeverson; Frazzon, Ana P G

2016-03-01

The microbiota of wild marine mammals is poorly understood, perhaps due to the migratory habits of some species and the difficulty in obtaining samples. Using high-throughput sequencing, the present study examines the faecal bacterial community of wild young South American (Arctocephalus australis) and Subantarctic fur seals (A. tropicalis). Faecal samples from South American (n = 6) and Subantarctic fur seals (n = 4) found dead along the south coast of Brazil were collected. Sequences were assigned to taxa using the Ribosomal Database Project-Bayesian classifier. Diversity of the microbiota was assessed by categorization of sequence reads into operational taxonomic units. Results indicate that Firmicutes (88.556%-84.016%) was the predominant phylum in South American and Subantarctic fur seals. The distribution of Actinobacteria and Proteobacteria varied according to the fur seal species. Fusobacteria and Bacteroidetes represented less than 1% of the sequences. The most abundant order in both fur seals was Clostridiales (88.64% and 87.49%). Individual variable incidences were observed in the composition of family among the fur seals, though the families Lachnospiraceae, Peptostreptococcaceae, Ruminococcaceae and Coriobacteriaceae were more prevalent. This study provides insight into the faecal bacterial community of wild young South American and Subantarctic fur seals. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Analysis of oxygen binding-energy variations for BaO on W

NASA Astrophysics Data System (ADS)

Haas, G. A.; Shih, A.; Mueller, D.; Thomas, R. E.

Interatomic Auger analyses have been made of different forms of BaO layers on W substrates. Variations in Auger spectroscopy energies of the Ba4dBa5pO2p interatomic Auger transition were found to be largely governed by the O2p binding energy of the BaO adsorbate. This was illustrated by comparing results of the Auger data values with values derived from O2p binding energies using ultraviolet photoelectron spectroscopy. Very good agreement was observed not only for the W<100> substrate but also for the W<110> substrate which showed two oxygen-induced electronics state. Variations in binding energy were noted for different states of BaO lattice formation and for different amounts of oxidation, ranging from the transition of Ba to BaO and continuing to the BaO 2 stoichiometry and beyond. Effects were also reported for adsorbate alignment and thermal activation (i.e., reduction) of the oxidized state. An empirical relationship was found suggesting that the more tightly bound the O2p states of the BaO adsorbate were, the lower its work function would be. This link between binding energy and work function was observed to be valid not only for cases of poisoning by oxidation, but held as well during reactivation by the subsequent reduction of the oxide. In addition, this relationship also appeared to predict the low work function obtained through the introduction of substances such as Sc to the BaO-W system. Possible qualitative reasons which might contribute to this are discussed in terms of enhanced dipole effects and shifts in band structure.

Testing of molded high temperature plastic actuator road seals for use in advanced aircraft hydraulic systems

NASA Technical Reports Server (NTRS)

Waterman, A. W.; Huxford, R. L.; Nelson, W. G.

1976-01-01

Molded high temperature plastic first and second stage rod seal elements were evaluated in seal assemblies to determine performance characteristics. These characteristics were compared with the performance of machined seal elements. The 6.35 cm second stage Chevron seal assembly was tested using molded Chevrons fabricated from five molding materials. Impulse screening tests conducted over a range of 311 K to 478 K revealed thermal setting deficiencies in the aromatic polyimide molding materials. Seal elements fabricated from aromatic copolyester materials structurally failed during impulse cycle calibration. Endurance testing of 3.85 million cycles at 450 K using MIL-H-83283 fluid showed poorer seal performance with the unfilled aromatic polyimide material than had been attained with seals machined from Vespel SP-21 material. The 6.35 cm first stage step-cut compression loaded seal ring fabricated from copolyester injection molding material failed structurally during impulse cycle calibration. Molding of complex shape rod seals was shown to be a potentially controllable technique, but additional molding material property testing is recommended.

Effect of ring-shaped SiO2 current blocking layer thickness on the external quantum efficiency of high power light-emitting diodes

NASA Astrophysics Data System (ADS)

Zhou, Shengjun; Liu, Mengling; Hu, Hongpo; Gao, Yilin; Liu, Xingtong

2017-12-01

A ring-shaped SiO2 CBL underneath the p-electrode was employed to enhance current spreading of GaN-based light-emitting diodes (LEDs). Effects of ring-shaped SiO2 current blocking layer (CBL) thickness on optical and electrical characteristics of high power LEDs were investigated. A 190-nm-thick ring-shaped SiO2 CBL with inclined sidewalls was obtained using a combination of a thermally reflowed photoresist technique and an inductively coupled plasma (ICP) etching process, allowing for the deposition of conformal indium tin oxide (ITO) transparent conductive layer on sidewalls of ring-shaped SiO2 CBL. It was indicated that the external quantum efficiency (EQE) of high power LEDs increased with increasing thickness of ring-shaped SiO2 CBL. The EQE of high power LED with 190-nm-thick ring-shaped SiO2 CBL was 12.7% higher than that of high power LED without SiO2 CBL. Simulations performed with commercial SimuLED software package showed that the ring-shaped SiO2 CBL could significantly alleviate current crowding around p-electrode, resulting in enhanced current spreading over the entire high power LED structure.

Comparison of tree-ring δ18O and meteorological data from Java island, Indonesia

NASA Astrophysics Data System (ADS)

Watanabe, Y.; Hisamochi, R.; Sano, M.; Nakatsuka, T.; Tazuru, S.; Sugiyama, J.; Tsuda, T.; Tagami, T.

2016-12-01

Tree-ring has been widely recognized as a powerful tool to reconstruct the paleoclimate of terrestrial areas because it has an advantage of exact dating with annual resolution. Paleoclimate reconstruction based on tree-ring is, however, extremely limited in the tropics because it is difficult to acquire long-lived wood samples with annual tree-ring. In this study, as for four teak samples from central Java and six teak samples from western Java, we measured teak δ18O values on annual scale over the last 70 years to evaluate the conformity among oxygen isotopic variations of Javanese teak trees. As a result, oxygen isotopic time series of ten teak trees has significant correlations between each other, suggesting that Javanese teak δ18O values are affected by common climatic factor. In addition, there are significant positive correlations between teak δ18O values and precipitation during the dry season prior to growing season.

JT8D revised high-pressure turbine cooling and other outer air seal program

NASA Technical Reports Server (NTRS)

Gaffin, W. O.

1979-01-01

The JT8D high pressure turbine was revised to reduce leakage between the blade tip shrouds and the outer air seal, and engine testing was performed to determine the effect on performance. The addition of a second knife-edge on the blade tip shroud, the extension of the honeycomb seal land to cover the added knife-edge and an existing spoiler on the shroud, and a material substitution in the seal support ring to improve thermal growth characteristics are included. A relocation of the blade cooling air discharge to insure adequate cooling flow is required. Significant specific fuel consumption and exhaust gas temperature improvements were demonstrated with the revised turbine in sea level and simulated altitude engine tests. Inspection of the revised seal hardware after these tests showed no unusual wear or degradation.

Loss of ring current O+ ions due to interaction with Pc 5 waves

NASA Astrophysics Data System (ADS)

Hudson, Mary; Chan, Anthony; Roth, Ilan

1993-01-01

The behavior of ring current ions in low-frequency geomagnetic pulsations is investigated analytically and numerically. We focus primarily on ring current O+ ions, whose flux increases dramatically during geomagnetic storms and decays at a rate which is not fully explained by collisional processes. This paper presents a new loss mechanism for the O+ ions due to the combined effects of convection and corotation electric fields and interaction with Pc 5 waves (wave period: 150-600 s) via a magnetic drift-bounce resonance. A test particle code has been developed to calculate the motion of the ring current O+ ions in a time-independent dipole magnetic field, and convection and corotation electric fields, plus Pc 5 wave fields, for which a simple analytical model has been formulated based on spacecraft observations. For given fields, whether a particle gains or loses energy depends on its initial kinetic energy, pitch angle at the equatorial plane, and the position of its guiding center with respect to the azimuthal phase of the wave. The ring current O+ ions show a dispersion in energies and L values with decreasing local time across the dayside, and a bulk shift to lower energies and higher L values. The former is due to the wave-particle interaction causing the ion to gain or lose energy, while the latter is due to the convection electric field. Our simulations show that, due to the interaction with the Pc 5 waves, the particle's kinetic energy can drop below that required to overcome the convection potential and the particle will be lost to the dayside magnetopause by a sunward E×B drift. This may contribute to the loss of O+ ions at intermediate energies (tens of keV) observed during the recovery phase of geomagnetic storms.

Contracting/expanding self-sealing cryogenic tube seals

NASA Technical Reports Server (NTRS)

Jia, Lin X. (Inventor)

1997-01-01

Contracting/expanding self-sealing cryogenic tube seals are disclosed which use the different properties of thermal contraction and expansion of selected dissimilar materials in accord with certain design criteria to yield self-tightening seals via sloped-surface sealing. The seals of the subject invention are reusable, simple to assemble, adaptable to a wide variety of cryogenic applications.

Contracting/expanding self-sealing cryogenic tube seals

NASA Technical Reports Server (NTRS)

Jia, Lin X. (Inventor)

1997-01-01

Contracting/expanding self-sealing cryogenic tube seals are disclosed which use the different properties of thermal contraction and expansion of selected dissimilar materials in accord with certain design criteria to yield self-tightening seals via sloped-surface sealing. The seals of the subject invention are reusable, simple to assemble, and adaptable to a wide variety of cryogenic applications.

Climate and Streamflow Reconstruction on the São Francisco Basin, Brazil, Using Tree-Ring Data

NASA Astrophysics Data System (ADS)

Pereira, G. D. A.; Barbosa, A. C. M. C.; Granato-Souza, D.; Stahle, D. W.; Torbenson, M.; dos Santos, R. M.; Rodrigues Alves Delfino Barbosa, J. P.

2017-12-01

The São Francisco River crosses the most drought-prone region of Brazil and regional economic dynamics are dependent on the water availability in the basin. The seasonally dry forests are widely distributed in the basin, where Cedrela fissilis Vell (cedro) are frequently found. This semi-arid region provides a favorable setting where the deciduous cedro trees form well-defined semi-ring porous annual rings that can be exactly crossdated and used to build climate sensitive chronologies. Therefore, we have developed chronologies of cedro from seasonally dry forest fragments of three sites located in the middle-sector of the São Francisco River basin and south limit of the Brazilian Drought Polygon. The samples were analyzed according to standard procedures: sample preparation, ring count, crossdating and measurement of the tree rings. Dating quality was tested using the computer program COFECHA and ring-width time series where detrended and standardized to produce the final index chronology using the ARSTAN program. The results show that crossdating within and among trees from different sites demonstrate the potential to expand the spatial sampling. The tree-ring chronologies are sensitive with wet season precipitation totals (October - March), and can explain approximately 40% of the variance (1961-2015). Significant correlation was also observed with total annual discharge of the Rio São Francisco River measured at Barra (r=0.48; 1961-2015). However, the correlation disapears after 1993 (r=0.64 for 1961-1993, but r=-0.004 for 1994-2015) and we suspect that the stream gage at Barra has been impacted by human activity. Tree-ring chronologies can provide important information on climate and streamflow variability of São Francisco River, where hydrological records are often short and discontinuous. This chronology is now being extended with 150-yr old trees from the region and may be used to reconstruct climate and streamflow records back to the pre

Piston and Ring Assembly Friction Studies in Cummins 903 Engine

DTIC Science & Technology

1989-06-01

5.0 um/div, horiz = 1.0 mm/div, Sample Interval of 7.0 um 121 Cr Oxide plasma ring on Cummins kaman-Cr Oxide, non lubricated 1.88I .9B 1I .8e8 I T 48...Chromium Oxide Liner, No Lubricant 122 Cr Oxide Plasma ring on Cummins-Naman Cr Oxide, Synthetic A oil 1.88- .908 I .788 T 1 .680 N .48 f C 38" " : " • Oo

Laboratory development and field demonstration of self-sealing/self-healing landfill liner.

PubMed

Shi, Caijun; Booth, Rob

2005-01-01

The self-sealing/self-healing (SS/SH) barrier concept is based on the principle that two or more parent materials placed in vertical or horizontal layers will react at their interfaces to form insoluble reaction products. These products constitute a seamless impermeable seal, which is resistant to the transmission of leachate and contaminants. A SS/SH liner formulation was developed in the laboratory and demonstrated at the Sudokwon landfill site in South Korea. Laboratory testing results indicated that a seal with a hydraulic conductivity less than 10(-9) m/s formed after two to four weeks of curing at room temperature, and the seal healed itself after it was fractured. The use of the soil from the Sudokwon landfill site instead of sand as the matrix of the parent materials in the SS/SH liner retarded the sealing and healing of the seal, but did not show an obvious effect on the overall sealing and healing capacity of the seal at early stages. The construction and installation of the field demonstration SS/SH liner were carried out in the same way as for a soil cement liner. The quality of the liner was ensured by the enforcement of quality analysis/quality control procedures during installation. A single sealed ring infiltration test was performed on the field demonstration liner 36 days after the installation was completed. The measurement of water infiltration rate indicated that the liner healed after it was fractured. However, the long-term sealing and healing capacity needs to be further investigated.

Surface atoms in Sc-O/W(1 0 0) system as Schottky emitter at high temperature

NASA Astrophysics Data System (ADS)

Tsujita, T.; Iida, S.; Nagatomi, T.; Takai, Y.

2003-12-01

The chemical bonding state of surface atoms in the Sc-O/W(1 0 0) system as a Schottky emitter was investigated at high temperature using a profile of Auger electron peaks to elucidate the mechanism of the marked reduction of the work function of the Sc-O/W(1 0 0) Schottky emitter. For this, Sc-deposited W(1 0 0), oxygen-exposed W(1 0 0) and Sc surfaces were prepared as reference surfaces. A comparison of the profiles of the Auger electron peaks from the Sc-O/W(1 0 0) surface with those from the reference surfaces has revealed that oxygen and Sc atoms on the Sc-O/W(1 0 0) surface form the Sc-O complexes at the operating temperature of the Sc-O/W(1 0 0) emitter of 1400 K. In addition, the ratio of the number of Sc atoms to that of oxygen atoms is estimated as 1:1 by the quantitative analysis of the AES peaks. The present results strongly suggest that the work function of the Sc-O/W(1 0 0) emitter is caused by the formation of Sc-O electric dipoles aligning into the p(2 × 1)-p(1 × 2) double-domain structure [Surf. Sci. 523 (2003) L37] on the Sc-O/W(1 0 0) surface at the operating temperature.

High thermal expansion, sealing glass

DOEpatents

Brow, R.K.; Kovacic, L.

1993-11-16

A glass composition is described for hermetically sealing to high thermal expansion materials such as aluminum alloys, stainless steels, copper, and copper/beryllium alloys, which includes between about 10 and about 25 mole percent Na[sub 2]O, between about 10 and about 25 mole percent K[sub 2]O, between about 5 and about 15 mole percent Al[sub 2]O[sub 3], between about 35 and about 50 mole percent P[sub 2]O[sub 5] and between about 5 and about 15 mole percent of one of PbO, BaO, and mixtures thereof. The composition, which may also include between 0 and about 5 mole percent Fe[sub 2]O[sub 3] and between 0 and about 10 mole percent B[sub 2]O[sub 3], has a thermal expansion coefficient in a range of between about 160 and 210[times]10[sup [minus]7]/C and a dissolution rate in a range of between about 2[times]10[sup [minus]7] and 2[times]10[sup [minus]9]g/cm[sup 2]-min. This composition is suitable to hermetically seal to metallic electrical components which will be subjected to humid environments over an extended period of time.

Conformational behavior of phenylglycines and hydroxyphenylglycines and non-planarity of phenyl rings.

PubMed

Nandel, Fateh S; Shafique, Mohd

2014-10-01

The non-proteinogenic amino acids--phenylglycine (PG) and hydroxyphenylglycine (HPG) are crucial components of certain peptidic natural products and are important for the preparation of various medicines. In this, study, the conformation of model dipeptides Ac-X-NHMe of PG, p-HPG and 3, 5-di-hydroxyphenylglycine (3, 5-DHPG) was studied both in R and S form by quantum mechanical (QM) and molecular dynamics approaches. On the energy scale, the conformational states of these molecules in both the R and S were found to be degenerate by QM studies, stabilized by non-covalent interactions like carbonyl--carbonyl interactions, carbonyl-lp .. π (aromatic ring) interactions etc. These interactions disappeared/weakened due to interaction of water molecules with carbonyl groups of backbone in simulation and water was found to interact with the aromatic ring through O(w)-H .. π or O(w)lp .. π interactions. The degeneracy of conformational states was lifted in favor of R-form of PG and DHPG and water molecules interactions with aromatic ring led to non-planarity of the aromatic ring. In simulation studies, irrespective of the starting geometry, the Φ, ψ values for the R form correspond to inverse β/inverse collagen region and for the S-form, the Φ, ψ values correspond to β/collagen region i.e., adopt single conformation. The obtained results were in conformity with the CD spectroscopic data on D-PG and D-p-HPG. The conformational behavior of the unusual amino acids might be of great help in designing of bioactive peptides/peptide based drugs to be realized in single conformation--an essential requirement.

The MIL-88A-Derived Fe3O4-Carbon Hierarchical Nanocomposites for Electrochemical Sensing

PubMed Central

Wang, Li; Zhang, Yayun; Li, Xia; Xie, Yingzhen; He, Juan; Yu, Jie; Song, Yonghai

2015-01-01

Metal or metal oxides/carbon nanocomposites with hierarchical superstructures have become one of the most promising functional materials in sensor, catalysis, energy conversion, etc. In this work, novel hierarchical Fe3O4/carbon superstructures have been fabricated based on metal-organic frameworks (MOFs)-derived method. Three kinds of Fe-MOFs (MIL-88A) with different morphologies were prepared beforehand as templates, and then pyrolyzed to fabricate the corresponding novel hierarchical Fe3O4/carbon superstructures. The systematic studies on the thermal decomposition process of the three kinds of MIL-88A and the effect of template morphology on the products were carried out in detail. Scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermal analysis were employed to investigate the hierarchical Fe3O4/carbon superstructures. Based on these resulted hierarchical Fe3O4/carbon superstructures, a novel and sensitive nonenzymatic N-acetyl cysteine sensor was developed. The porous and hierarchical superstructures and large surface area of the as-formed Fe3O4/carbon superstructures eventually contributed to the good electrocatalytic activity of the prepared sensor towards the oxidation of N-acetyl cysteine. The proposed preparation method of the hierarchical Fe3O4/carbon superstructures is simple, efficient, cheap and easy to mass production. It might open up a new way for hierarchical superstructures preparation. PMID:26387535

Stable carbon isotopic composition of tree rings from a pine tree from Augustów Wilderness, Poland, as a temperature and local environment conditions indicator.

PubMed

Pawelczyk, Slawomira; Pazdur, Anna; Halas, Stanislaw

2004-06-01

Tree rings can be used as archives of climatic and environmental data with annual resolution. Tree rings widths, maximum late wood density and other parameters as stable composition in tree rings can be used for the reconstruction of past climatic and environmental changes. Stable carbon isotope ratios in tree rings may provide valuable information on past climatic conditions. 13C/12C ratios of plant organic matter can reflect corresponding 13C/12C ratio of atmospheric CO2 during formation of the rings. Investigations of isotopic carbon composition in tree rings from in the ecologically clean the Augustów Wilderness region in the north-eastern part of Poland (22 degrees 58'E, 53 degrees 51'N) (nowadays a sanctuary) were undertaken. Series of delta13C in alpha-cellulose and in wholewood were acquired. Those measurements constituted a part of more complex investigations of carbon isotope composition in tree rings including the measurements of radiocarbon concentration and tree ring widths. This article presents preliminary results. It is argued that contrary to the tree ring widths and delta13C in wholewood that do not reveal significant correlation with temperature, the variation of delta13C in the latewood alpha-cellulose is correlated with combined July and August temperatures. Copyright 2004 Taylor and Francis Ltd.

Pressure Actuated Leaf Seals for Improved Turbine Shaft Sealing

NASA Technical Reports Server (NTRS)

Grondahl, Clayton

2006-01-01

This presentation introduces a shaft seal in which leaf seal elements are constructed from slotted shim material formed and layered into a frusto-conical assembly. Limited elastic deflection of seal leaves with increasing system pressure close large startup clearance to a small, non-contacting, steady state running clearance. At shutdown seal elements resiliently retract as differential seal pressure diminishes. Large seal clearance during startup and shutdown provides a mechanism for rub avoidance. Minimum operating clearance improves performance and non-contacting operation promises long seal life. Design features of this seal, sample calculations at differential pressures up to 2400 psid and benefit comparison with brush and labyrinth seals is documented in paper, AIAA 2005 3985, presented at the Advanced Seal Technology session of the Joint Propulsion Conference in Tucson this past July. In this presentation use of bimetallic leaf material will be discussed. Frictional heating of bimetallic leaf seals during a seal rub can relieve the rub condition to some extent with a change in seal shape. Improved leaf seal rub tolerance is expected with bimetallic material.

West Nile Flavivirus Polioencephalomyelitis in a harbor seal (Phoca vitulina).

PubMed

Del Piero, F; Stremme, D W; Habecker, P L; Cantile, C

2006-01-01

A 12-year-old male harbor seal presented with progressive signs of neurologic dysfunction including head tremors, muzzle twitching, clonic spasms, and weakness. Lesions included polioencephalomyelitis with glial nodules, spheroids, neuronophagia, ring hemorrhages, and a few neutrophils. Neurons, fibers, and glial nodules were multifocally colonized with intracytoplasmic West Nile flavivirus antigens that were demonstrated using indirect immunohistochemical analysis. Flavivirus on cultured cells also was isolated and was identified by use of monoclonal antibodies and reverse transcriptase-polymerase chain reaction analysis. Clinical signs of disease and lesion morphology and distribution were similar to those of equine West Nile virus infection. Similar to horses, alpacas, humans, dogs, and reptiles, seals can be dead-end hosts of West Nile virus.

Polyoxometal cations within polyoxometalate anions. Seven-coordinate uranium and zirconium heteroatom groups in [(UO2)12(μ3-O)4(μ2-H2O)12(P2W15O56)4]32- and [Zr4(μ3-O)2(μ2-OH)2(H2O)4 (P2W16O59)2]14-

NASA Astrophysics Data System (ADS)

Gaunt, Andrew J.; May, Iain; Collison, David; Travis Holman, K.; Pope, Michael T.

2003-08-01

Two new composite polyoxotungstate anions with unprecedented structural features, [(UO2)12(μ3-O)4(μ2-H2O)12(P2W15O56)4]32- (1) and [Zr4(μ3-O)2(μ2-OH)2(H2O)4 (P2W16O59)2]14- (2) contain polyoxo-uranium and -zirconium clusters as bridging units. The anions are synthesized by reaction of Na12[P2W15O56] with solutions of UO2(NO3)2 and ZrCl4. The structure of 1 in the sodium salt contains four [P2W15O56]12- anions assembled into an overall tetrahedral cluster by means of trigonal bridging groups formed by three equatorial-edge-shared UO7 pentagonal bipyramids. The structure of anion 2 consists of a centrosymmetric assembly of two [P2W16O59]12- anions linked by a {Zr4O2(OH)2(H2O)4}10+ cluster. Both complexes in solution yield the expected two-line 31P-NMR spectra with chemical shifts of -2.95, -13.58 and -6.45, -13.69 ppm, respectively.

Redox sensitivity of the MyD88 immune signaling adapter.

PubMed

Stottmeier, Benjamin; Dick, Tobias P

2016-12-01

The transcription factor nuclear factor-κB (NF-κB) mediates expression of key genes involved in innate immunity and inflammation. NF-κB activation has been repeatedly reported to be modulated by hydrogen peroxide (H 2 O 2 ). Here, we show that the NF-κB-activating signaling adapter myeloid differentiation primary response gene 88 (MyD88) is highly sensitive to oxidation by H 2 O 2 and may be redox-regulated in its function, thus facilitating an influence of H 2 O 2 on the NF-κB signaling pathway. Upon oxidation, MyD88 forms distinct disulfide-linked conjugates which are reduced by the MyD88-interacting oxidoreductase nucleoredoxin (Nrx). MyD88 cysteine residues functionally modulate MyD88-dependent NF-κB activation, suggesting a link between MyD88 thiol oxidation state and immune signaling. Copyright © 2016 Elsevier Inc. All rights reserved.

Fluctuations in Tree Ring Cellulose d18O during the Little Ice Age Correlate with Solar Activity

NASA Astrophysics Data System (ADS)

Yamaguchi, Y. T.; Yokoyama, Y.; Miyahara, H.; Nakatsuka, T.

2008-12-01

The Maunder Minimum (AD1645-1715), when sunspots became exceedingly rare, is known to coincide with the coldest period during the Little Ice Age. This is a useful period to investigate possible linkage between solar activity and climate because variation in solar activity was different from that of today. The solar cycle length was longer (14 and 28 years) than that of today (11 and 22 years) hence any climate archives that have similar periodic changes could be separated from other internal climate forcing. We have reported that Greenland temperature variations coincided with decadal-scale variability in solar activity during the Maunder Minimum (Miyahara et al. 2008). Here we report interannual and intra-annual relative humidity (RH) variations in central Japan during that period, using tree ring cellulose d18O in a 382-year-old Japanese cedar tree (Cryptomeria japonica). The isotopic composition of tree rings can be a powerful tool to study the relationship between solar activity and climate, because we can directly compare solar activity (D14C) and climate (d18O) with little dating error. The climate proxy obtained using tree ring cellulose d18O is correlated both negatively and positively with RH and d18O in precipitation, respectively. Since d18O in precipitation is negatively correlated with the amount of precipitation in the monsoon area, tree ring cellulose d18O can be a reliable proxy for past RH and/or amount of precipitation in the area of the interest. Tree ring cellulose d18O of the cedar tree during AD1938-1998 in fact correlates significantly with the mean RH in June in central Japan. Tree ring d18O inferred RH variability during the Maunder Minimum shows distinct high RH spikes with an approximate 14-year quasiperiodicity. All nine solar minima during AD1640-1756 deduced from tree ring D14C coincided with high RH spikes, and seven of which coincided within 1-year. Interannual RH variations also coincided with Greenland temperature during this

Underwater localization of pure tones by harbor seals (Phoca vitulina).

PubMed

Bodson, Anaïs; Miersch, Lars; Dehnhardt, Guido

2007-10-01

The underwater sound localization acuity of harbor seals (Phoca vitulina) was measured in the horizontal plane. Minimum audible angles (MAAs) of pure tones were determined as a function of frequency from 0.2 to 16 kHz for two seals. Testing was conducted in a 10-m-diam underwater half circle using a right/left psychophysical procedure. The results indicate that for both harbor seals, MAAs were large at high frequencies (13.5 degrees and 17.4 degrees at 16 kHz), transitional at intermediate frequencies (9.6 degrees and 10.1 degrees at 4 kHz), and particularly small at low frequencies (3.2 degrees and 3.1 degrees at 0.2 kHz). Harbor seals seem to be able to utilize both binaural cues, interaural time differences (ITDs) and interaural intensity differences (IIDs), but a significant decrease in the sound localization acuity with increasing frequency suggests that IID cues may not be as robust as ITD cues under water. These results suggest that the harbor seal can be regarded as a low-frequency specialist. Additionally, to obtain a MAA more representative of the species, the horizontal underwater MAA of six adult harbor seals was measured at 2 kHz under identical conditions. The MAAs of the six animals ranged from 8.8 degrees to 11.7 degrees , resulting in a mean MAA of 10.3 degrees .

Design of micro-ring optical sensors and circuits for integration on optical printed circuit boards (O-PCBs)

NASA Astrophysics Data System (ADS)

Lee, El-Hang; Lee, Hyun S.; Lee, S. G.; O, B. H.; Park, S. G.; Kim, K. H.

2007-05-01

We report on the design of micro-ring resonator optical sensors for integration on what we call optical printed circuit boards (O-PCBs). The objective is to realize application-specific O-PCBs, either on hard board or on flexible board, by integrating micro/nano-scale optical sensors for compact, light-weight, low-energy, high-speed, intelligent, and environmentally friendly processing of information. The O-PCBs consist of two-dimensional planar arrays of micro/nano-scale optical wires, circuits and devices that are interconnected and integrated to perform the functions of sensing and then storing, transporting, processing, switching, routing and distributing optical signals that have been collected by means of sensors. For fabrication, the polymer and organic optical wires and waveguides are first fabricated on a board and are used to interconnect and integrate sensors and other micro/ nano-scale photonic devices. Here, in our study, we focus on the sensors based on the micro-ring structures. We designed bio-sensors using silicon based micro-ring resonator. We investigate the characteristics such as sensitivity and selectivity (or quality factor) of micro-ring resonator for their use in bio-sensing application. We performed simulation studies on the quality factor of micro-ring resonators by varying the radius of the ring resonators and the separation between adjacent waveguides. We introduce the effective coupling coefficient as a realistic value to describe the strength of the coupling in micro-ring resonators.

The chemistry of (ring)Ru sup 2+ (ring = tetramethylthiophene, p-cymene)

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

Ganja, E.A.; Rauchfuss, T.B.; Stern, C.L.

1991-01-01

Described are the compounds ((ring)Ru(OTf){sub 2}){sub x}, where ring = 2,3,4,5-tetramethylthiophene (TMT, 1), and p-cymene (2). These electrophilic reagents serve as precursors to ((ring)RuL{sub 3}){sup 2+}, where L{sub 3} = (H{sub 2}O){sub 3}, (NH{sub 3}){sub 3}, and (PH{sub 3}){sub 3}. Solutions of 1 and 2 react with carbon monoxide to give (ring)Ru(CO)(OTf){sub 2}. The addition of thiophenes to CH{sub 2}Cl{sub 2} solutions of 1 or 2 leads to the precipitation of the sandwich compounds ((ring)(SC{sub 4}R{sub 4})Ru)(OTf){sub 2}, where SC{sub 4}R{sub 4} = thiophene, 2,5-dimethylthiophene, and TMT. ((TMT)Ru(H{sub 2}O){sub 3})(OTf){sub 2} was characterized by single-crystal X-ray crystallography, which established amore » piano-stool geometry with a planar TMT ligand. ((TMT)Ru(D{sub 2}O){sub 3})(OTf){sub 2} decomposes in D{sub 2}O solution at 150C to give ((TMT){sub 2}Ru){sup 2+}, which undergoes selective deuteration at the 2,5-methyl groups. D{sub 2}O solutions of ((TMT){sub 2}Ru){sup 2+} undergo photochemical loss of one TMT ligand in water to give ((TMT)Ru(H{sub 2}O){sub 3}){sup 2+}. A procedure is described for the reversible loading of 1 onto {gamma}-alumina, which in turn was characterized by {sup 13}C CP-MAS NMR spectroscopy.« less

Dynamic analysis of the mechanical seals of the rotor of the labyrinth screw pump

NASA Astrophysics Data System (ADS)

Lebedev, A. Y.; Andrenko, P. M.; Grigoriev, A. L.

2017-08-01

A mathematical model of the work of the mechanical seal with smooth rings made from cast tungsten carbide in the condition of liquid friction is drawn up. A special feature of this model is the allowance for the thermal expansion of a liquid in the gap between the rings; this effect acting in the conjunction with the frictional forces creates additional pressure and lift which in its turn depends on the width of the gap and the speed of sliding. The developed model displays the processes of separation, transportation and heat removal in the compaction elements and also the resistance to axial movement of the ring arising in the gap caused by the pumping effect and the friction in the flowing liquid; the inertia of this fluid is taken into account by the mass reduction method. The linearization of the model is performed and the dynamic characteristics of the transient processes and the forced oscillations of the device are obtained. The conditions imposed on the parameters of the mechanical seal are formulated to provide a regime of the liquid friction, which minimizes the wear.

STS-88 in-flight crew portrait

NASA Image and Video Library

1998-12-14

S88-E-5169 (12-14-98) --- A pre-set electronic still camera (ESC) was used to take one of the traditional in-flight crew portraits for the STS-88 members on Endeavour's mid deck. From the left are Jerry L. Ross, James H. Newman, Robert D. Cabana, Frederick W. (Rick) Sturckow, Nancy J. Currie and Sergei K. Krikalev. Krikalev, representing the Russian Space Agency (RSA), has been assigned as one of the crew members for the first ISS crew. A banner representing the participating countries for ISS and a model of the connected Unity-Zarya modules are in the background. The photo was taken at 23:41:40, Dec. 14.

Fault seal analysis of Okan and Meren fields, Nigeria

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

Eisenberg, R.A.; Brenneman, R.J.; Adeogba, A.A.

The sealing capacity and the dynamic seal behavior of faults between juxtaposed reservoirs were analyzed for Okan and Meren fields, offshore Nigeria. In both fields correlations were found between reservoir performance, juxtaposed fluid types, oil geochemistry, interpreted fluid contact relationships, fault sealing/leaking condition, and calculated smear gouge ratios. Integration of these data has been invaluable in quantifying fault seal risk and may effect depletion strategies for fault-juxtaposed reservoirs within these fields. Fault plane sections defined reservoir juxtapositions and aided visualization of potential cross-fault spill points. Smear gouge ratios calculated from E-logs were used to estimate the composition of fault-gouge materialsmore » between the juxtaposed reservoirs. These tools augmented interpretation of seal/nonseal character based on fluid contact relationships in proved reservoirs and, in addition, were used to quantify fault seal risk of untested fault-dependent closures in Okan. The results of these analyses were then used to interpret production-induced fault seal breakdown within the G-sands and also to risk seal integrity of fault dependent closures within the untested O-sands in an adjacent, upthrown fault block. Within this fault block the presence of potential fault intersection leak points and large areas of sand/sand juxtaposition with high smear gouge ratios (low sealing potential) limits potential reserves within the O-sand package. In Meren Field the E- and G-sands are juxtaposed, on different pressure decline, geochemically distinct, and are characterized by low smear gouge ratios. In contrast, specific G- and H-sands, juxtaposed across the same fault, contain similar OOWCs and are characterized by high smear gouge ratios. The cross-sealing and/or cross-leaking nature of compartment boundaries at Meren is related to fault displacement variation and the composition of displaced stratigraphy.« less

Structures for attaching or sealing a space between components having different coefficients or rates of thermal expansion

DOEpatents

Corman, Gregory Scot; Dean, Anthony John; Tognarelli, Leonardo; Pecchioli, Mario

2005-06-28

A structure for attaching together or sealing a space between a first component and a second component that have different rates or amounts of dimensional change upon being exposed to temperatures other than ambient temperature. The structure comprises a first attachment structure associated with the first component that slidably engages a second attachment structure associated with the second component, thereby allowing for an independent floating movement of the second component relative to the first component. The structure can comprise split rings, laminar rings, or multiple split rings.

Transposon elements in maize white seedling 3, allele w3-8686, w3-kermicle-1 and w3-88-89-3563-33

USDA-ARS?s Scientific Manuscript database

Maize white seedling 3 (w3) has served as a model albino-seedling mutant since its discovery in 1923. We show that the w3 phenotype is caused by disruptions in homogentisate solanesyl transferase (HST), an enzyme that catalyzes the committed step in plastoquinone-9 (PQ9) biosynthesis. This reaction ...

High expansion, lithium corrosion resistant sealing glasses

DOEpatents

Brow, Richard K.; Watkins, Randall D.

1991-01-01

Glass compositions containing CaO, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, SrO and BaO in various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with pin materials of 446 Stainless Steel and Alloy-52 rather than molybdenum, for use in harsh chemical environments, specifically in lithium batteries.

High expansion, lithium corrosion resistant sealing glasses

DOEpatents

Brow, R.K.; Watkins, R.D.

1991-06-04

Glass compositions containing CaO, Al[sub 2]O[sub 3], B[sub 2]O[sub 3], SrO and BaO in various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with pin materials of 446 Stainless Steel and Alloy-52 rather than molybdenum, for use in harsh chemical environments, specifically in lithium batteries.

Plasmonic resonance in planer split ring trimer

NASA Astrophysics Data System (ADS)

Xu, Haiqing; Li, Hongjian; Xiao, Gang

2014-12-01

We have numerically investigated the plasmon properties supported by asymmetry planer split ring trimer structures. We investigate the modification of gap distance, thickness and gap width on the transmission properties of the weak coupling model (g is larger than or equal to 120 nm, d=48 nm, t is larger than 30 nm, w1=200 nm, and w2=40 nm), as the coupling becomes weaker, the first peak sharply attenuates, the second peak slightly decreases, the transmission dip in the near-infrared region becomes shallow, and they are very sensitive to the gap distance between two small split ring pairs and the thickness and gap width of the big split ring. We also study the change of gap distance on the strong coupling model (g is smaller than or equal to 40 nm, d=24 nm, t=10 nm, w1=80 nm, and w2=20 nm), there exists a new Fano resonance peak, the strongest peak in visible region becomes symmetry, while the peak in near-infrared region becomes asymmetry. The resonator design strategy opens up a rich pathway for the implementation of optimized optical properties for specific applications.

Sealing device for providing a seal in a turbomachine

DOEpatents

Lacy, Benjamin Paul; Kottilingam, Srikanth Chandrudu; Porter, Christopher Donald; Schick, David Edward; Weber, David Wayne

2016-08-16

Sealing device for providing seals between adjacent components, and turbomachines utilizing such sealing devices, are provided. A sealing device includes a seal plate insertable between the adjacent components, the seal plate comprising a first face and an opposing second face. The sealing device further includes a plurality of pins extending from one of the first face or the second face, the plurality of pins configured to space the one of the first face or the second face from contact surfaces of the adjacent components.

Seal assembly

DOEpatents

Johnson, Roger Neal; Longfritz, William David

2001-01-01

A seal assembly that seals a gap formed by a groove comprises a seal body, a biasing element, and a connection that connects the seal body to the biasing element to form the seal assembly. The seal assembly further comprises a concave-shaped center section and convex-shaped contact portions at each end of the seal body. The biasing element is formed from an elastic material and comprises a convex-shaped center section and concave-shaped biasing zones that are opposed to the convex-shaped contact portions. The biasing element is adapted to be compressed to change a width of the seal assembly from a first width to a second width that is smaller than the first width. In the compressed state, the seal assembly can be disposed in the groove. After release of the compressing force, the seal assembly expands. The contact portions will move toward a surface of the groove and the biasing zones will move into contact with another surface of the groove. The biasing zones will bias the contact portions of the seal body against the surface of the groove.

Modeling Saturnshine in Cassini Images of the Rings

NASA Astrophysics Data System (ADS)

Dones, Henry C.; Weiss, J. W.; Porco, C. C.; DiNino, D.; Skinner, R.

2013-10-01

In some viewing geometries, such as large solar phase angles or small solar elevation angles, the light reflected by or transmitted through Saturn's rings can be dominated by Saturnshine, i.e., illumination of the rings by the planet. Saturnshine results in longitudinal variations in the reflectivity of the rings. In addition, Saturn's A Ring and, to a lesser extent, B Ring, show intrinsic longitudinal variations ("azimuthal asymmetry") due to self-gravity wakes. Any attempt to infer physical properties of ring particles and their spatial distribution using ring photometry must consider both Saturnshine and self-gravity wakes. "Ringshine," in turn, complicates photometry of Saturn itself [1]. We have improved the Saturnshine model in [2], which applies a ray-tracing code to N-body simulations of a patch of Saturn's rings, by incorporating measurements of the planet's reflectivity in Cassini images taken in a range of viewing geometries through a number of broadband filters. We will compare the results of our photometric model with measurements of the I/F of the main rings, and will attempt to constrain the intrinsic properties of ring particles, such as their coefficients of restitution in collisions and internal densities. We thank the Cassini project for support. [1] Skinner, R.W., and Weiss, J.W. (2011). http://serc.carleton.edu/cismi/undergrad_research/posters/52679.html [2] Porco, C.C., et al. (2008). Astron J. 136, 2172-2200

Potential utility of tree ring δ18O series for reconstructing precipitation records from the lower reaches of the Yangtze River, southeast China

NASA Astrophysics Data System (ADS)

Xu, Chenxi; Ge, Junyi; Nakatsuka, Takeshi; Yi, Liang; Zheng, Huaizhou; Sano, Masaki

2016-04-01

In this study, we investigated the interannual and intraannual variabilities in the oxygen isotope composition (δ18O) preserved in the tree ring cellulose of Pinus taiwanensis in the lower reaches of the Yangtze River, southeast China, to explore its potential utility for precipitation reconstruction over the period of 1855-2013. Intraannual variations of tree ring cellulose δ18O show distinct annual cycles that are characterized by δ18O maxima in the early growth near the ring boundary and δ18O minima in the middle and late portions of the ring. Seasonal patterns of tree ring δ18O were influenced by August-October typhoons. The tree ring cellulose δ18O was measured in both young and old trees to test for the juvenile effect. The results revealed no significant differences in the mean values and long-term trends in δ18O in the old and young trees. A response analysis indicated that tree ring δ18O correlated significantly with precipitation and relative humidity between May and October, and the δ18O chronology accounted for 37.4% of the actual variation in the May-October precipitation between 1951 and 2013. The extremely dry and wet years revealed by the tree ring δ18O-based reconstructed precipitation also corresponded to actual local drought and flood events from the documentary records. Reconstructed precipitation showed significant relationship with central tropical Pacific sea surface temperature, which indicated that El Niño-Southern Oscillation (ENSO) exerted influences on May-October precipitation in the lower reaches of the Yangtze River. In addition, the relationship between ENSO and precipitation weakened between 1920 and 1940, and low variance of ENSO from 1920 to 1940 may result in the damped ENSO's influences on precipitation in southeast China.

Burn rates of TiH2/KClO4/Viton and output testing of NASA SKD26100098-301 pressure cartridges

NASA Technical Reports Server (NTRS)

Holy, John A.

1993-01-01

The burn rates of the pyrotechnic TiH2/KClO4/Viton with a mass ratio of 30/65/5 have been measured as a function of pressure in nitrogen up to 312 MPa(45 Kpsi). The burn rates were fit to R = a pn, with a = 2.055 cm/sec/MPan and n = 0.472 between 0.15 MPa (22 psi) and 21.6 MPa (3.13 Kpsi) and a = 4.38 cm/sec/MPan and n = 0.266 between 70 MPa (10.15 Kpsi) and 312 MPa (45.25 Kpsi). The decrease in slope at the higher pressures is attributed to a diffusion limited reaction. No acoustically driven flame instabilities or large conductive-to-convective burn transitions were observed. Solid reaction products were analyzed by x-ray diffraction and scanning electron microscopy (SEM). X-ray diffraction detected only TiO2 and KC1. SEM showed that the particle size of the reaction products increased as the nitrogen pressure increased. There were no anomalous characteristics of the burn of this pyrotechnic that could be interpreted as a cause of the o-ring blow-by problem in the forward shear bolt assembly. Three NASA SKD26100098-301 pressure cartridges were fired into a fixed volume vessel that was sealed with an O-ring. A maximum pressure of 181.7 MPa(26,350 psi) was reached in around 100 ,mu sec for two shots fired into a volume of 16.3 cm3(0.996 in3). A maximum pressure of 33,460 psi was reached for one shot fired into a volume of 9.55 cm3(0.583 in3). The O-ring burned through on one shot in the larger volume and leaked on the other two thereby simulating the effects of an O-ring leak. The results imply that the piston in the shear bolt assembly would receive a large impulse even if there was a leak in an O-ring seal.

Fukushima derived radiocesium in subsistence-consumed northern fur seal and wild celery

DOE PAGES

Ruedig, Elizabeth; Duncan, Colleen; Dickerson, Bobette; ...

2015-11-28

In July 2014, our investigative team traveled to St. Paul Island, Alaska to measure concentrations of radiocesium in wild-caught food products, primarily northern fur seal (Callorhinus ursinus). The 2011 Fukushima Daiichi Nuclear Power Plant accident released radiocesium into the atmosphere and into the western Pacific Ocean; other investigators have detected Fukushima-derived radionuclides in a variety of marine products harvested off the western coast of North America. We tested two subsistence-consumed food products from St. Paul Island, Alaska for Fukushima-derived radionuclides: 54 northern fur seal, and nine putchki (wild celery, Angelica lucida) plants. Individual northern fur seal samples were below minimummore » detectable activity concentrations of 137Cs and 134Cs, but when composited, northern fur seal tissues tested positive for trace quantities of both isotopes. Radiocesium was detected at an activity concentration of 37.2 mBq 134Cs kg -1 f.w. (95% CI: 35.9–38.5) and 141.2 mBq 137Cs kg -1f.w. (95% CI: 135.5–146.8). The measured isotopic ratio, decay-corrected to the date of harvest, was 0.26 (95% CI: 0.25–0.28). The Fukushima nuclear accident released 134Cs and 137Cs in roughly equal quantities, but by the date of harvest in July 2014, this ratio was 0.2774, indicating that this population of seals has been exposed to small quantities of Fukushima-derived radiocesium. Activity concentrations of both 134Cs and 137Cs in putchki were below detection limits, even for composited samples. Northern fur seal is known to migrate between coastal Alaska and Japan and the trace 134Cs in northern fur seal tissue suggests that the population under study had been minimally exposed Fukushima-derived radionuclides. Despite this inference, the radionuclide quantities detected are small and no impact is expected as a result of the measured radiation exposure, either in northern fur seal or human populations consuming this species.« less

Fukushima derived radiocesium in subsistence-consumed northern fur seal and wild celery

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

Ruedig, Elizabeth; Duncan, Colleen; Dickerson, Bobette

In July 2014, our investigative team traveled to St. Paul Island, Alaska to measure concentrations of radiocesium in wild-caught food products, primarily northern fur seal (Callorhinus ursinus). The 2011 Fukushima Daiichi Nuclear Power Plant accident released radiocesium into the atmosphere and into the western Pacific Ocean; other investigators have detected Fukushima-derived radionuclides in a variety of marine products harvested off the western coast of North America. We tested two subsistence-consumed food products from St. Paul Island, Alaska for Fukushima-derived radionuclides: 54 northern fur seal, and nine putchki (wild celery, Angelica lucida) plants. Individual northern fur seal samples were below minimummore » detectable activity concentrations of 137Cs and 134Cs, but when composited, northern fur seal tissues tested positive for trace quantities of both isotopes. Radiocesium was detected at an activity concentration of 37.2 mBq 134Cs kg -1 f.w. (95% CI: 35.9–38.5) and 141.2 mBq 137Cs kg -1f.w. (95% CI: 135.5–146.8). The measured isotopic ratio, decay-corrected to the date of harvest, was 0.26 (95% CI: 0.25–0.28). The Fukushima nuclear accident released 134Cs and 137Cs in roughly equal quantities, but by the date of harvest in July 2014, this ratio was 0.2774, indicating that this population of seals has been exposed to small quantities of Fukushima-derived radiocesium. Activity concentrations of both 134Cs and 137Cs in putchki were below detection limits, even for composited samples. Northern fur seal is known to migrate between coastal Alaska and Japan and the trace 134Cs in northern fur seal tissue suggests that the population under study had been minimally exposed Fukushima-derived radionuclides. Despite this inference, the radionuclide quantities detected are small and no impact is expected as a result of the measured radiation exposure, either in northern fur seal or human populations consuming this species.« less

Fukushima derived radiocesium in subsistence-consumed northern fur seal and wild celery.

PubMed

Ruedig, Elizabeth; Duncan, Colleen; Dickerson, Bobette; Williams, Michael; Gelatt, Thomas; Bell, Justin; Johnson, Thomas E

2016-02-01

In July 2014, our investigative team traveled to St. Paul Island, Alaska to measure concentrations of radiocesium in wild-caught food products, primarily northern fur seal (Callorhinus ursinus). The 2011 Fukushima Daiichi Nuclear Power Plant accident released radiocesium into the atmosphere and into the western Pacific Ocean; other investigators have detected Fukushima-derived radionuclides in a variety of marine products harvested off the western coast of North America. We tested two subsistence-consumed food products from St. Paul Island, Alaska for Fukushima-derived radionuclides: 54 northern fur seal, and nine putchki (wild celery, Angelica lucida) plants. Individual northern fur seal samples were below minimum detectable activity concentrations of (137)Cs and (134)Cs, but when composited, northern fur seal tissues tested positive for trace quantities of both isotopes. Radiocesium was detected at an activity concentration of 37.2 mBq (134)Cs kg(-1) f.w. (95% CI: 35.9-38.5) and 141.2 mBq (137)Cs kg(-1) f.w. (95% CI: 135.5-146.8). The measured isotopic ratio, decay-corrected to the date of harvest, was 0.26 (95% CI: 0.25-0.28). The Fukushima nuclear accident released (134)Cs and (137)Cs in roughly equal quantities, but by the date of harvest in July 2014, this ratio was 0.2774, indicating that this population of seals has been exposed to small quantities of Fukushima-derived radiocesium. Activity concentrations of both (134)Cs and (137)Cs in putchki were below detection limits, even for composited samples. Northern fur seal is known to migrate between coastal Alaska and Japan and the trace (134)Cs in northern fur seal tissue suggests that the population under study had been minimally exposed Fukushima-derived radionuclides. Despite this inference, the radionuclide quantities detected are small and no impact is expected as a result of the measured radiation exposure, either in northern fur seal or human populations consuming this species. Published by Elsevier

An Annular Mechanical Temperature Compensation Structure for Gas-Sealed Capacitive Pressure Sensor

PubMed Central

Hao, Xiuchun; Jiang, Yonggang; Takao, Hidekuni; Maenaka, Kazusuke; Higuchi, Kohei

2012-01-01

A novel gas-sealed capacitive pressure sensor with a temperature compensation structure is reported. The pressure sensor is sealed by Au-Au diffusion bonding under a nitrogen ambient with a pressure of 100 kPa and integrated with a platinum resistor-based temperature sensor for human activity monitoring applications. The capacitance-pressure and capacitance-temperature characteristics of the gas-sealed capacitive pressure sensor without temperature compensation structure are calculated. It is found by simulation that a ring-shaped structure on the diaphragm of the pressure sensor can mechanically suppress the thermal expansion effect of the sealed gas in the cavity. Pressure sensors without/with temperature compensation structures are fabricated and measured. Through measured results, it is verified that the calculation model is accurate. Using the compensation structures with a 900 μm inner radius, the measured temperature coefficient is much reduced as compared to that of the pressure sensor without compensation. The sensitivities of the pressure sensor before and after compensation are almost the same in the pressure range from 80 kPa to 100 kPa. PMID:22969385

Low Leakage Turbine Shaft Seals for Advanced Combined Cycle Systems.

DTIC Science & Technology

1984-11-01

Both used feedwater -supplied buffer water as required by advanced combined cycle steam turbomachinery. It was shown to be advantageous, at least from...RD-fi149 372 LOW LEAKAGE’TURBINE SHAFT SEALS FOR ADVANCED COMBINED 1/2- CYCLE SYSTEMS(U) SOLAR TURBINES INC SAN DIEGO CA G W HOSANG NOV 84 SR84-R...4622-36 N88824-7B-C-5345 UNCLASSIFIED F/1 i/i NL AIONA L RUEA OF B 20NADS16 Final Report N 4 <Low Leakage Turbine Shaft Seals for Advanced Combined Cycle

Development of new sealed bipolar lead-acid battery

NASA Technical Reports Server (NTRS)

Attia, Alan I.; Rowlette, J. J.

1987-01-01

New light weight composite bipolar plates which can withstand the corrosive environment of the lead acid battery have made possible the construction of a sealed bipolar lead acid battery that promises to achieve very high specific power levels and substantially higher energy densities than conventional lead acid batteries. Performance projections based on preliminary experimental results show that the peak specific power of the battery can be as high as 90 kW/kg, and that a specific power of 5 kW/kg can be sustained over several thousand pulses.

Aspirating Seal Development: Analytical Modeling and Seal Test Rig

NASA Technical Reports Server (NTRS)

Bagepalli, Bharat

1996-01-01

This effort is to develop large diameter (22 - 36 inch) Aspirating Seals for application in aircraft engines. Stein Seal Co. will be fabricating the 36-inch seal(s) for testing. GE's task is to establish a thorough understanding of the operation of Aspirating Seals through analytical modeling and full-scale testing. The two primary objectives of this project are to develop the analytical models of the aspirating seal system, to upgrade using GE's funds, GE's 50-inch seal test rig for testing the Aspirating Seal (back-to-back with a corresponding brush seal), test the aspirating seal(s) for seal closure, tracking and maneuver transients (tilt) at operating pressures and temperatures, and validate the analytical model. The objective of the analytical model development is to evaluate the transient and steady-state dynamic performance characteristics of the seal designed by Stein. The transient dynamic model uses a multi-body system approach: the Stator, Seal face and the rotor are treated as individual bodies with relative degrees of freedom. Initially, the thirty-six springs are represented as a single one trying to keep open the aspirating face. Stops (Contact elements) are provided between the stator and the seal (to compensate the preload in the fully-open position) and between the rotor face and Seal face (to detect rub). The secondary seal is considered as part of the stator. The film's load, damping and stiffness characteristics as functions of pressure and clearance are evaluated using a separate (NASA) code GFACE. Initially, a laminar flow theory is used. Special two-dimensional interpolation routines are written to establish exact film load and damping values at each integration time step. Additionally, other user-routines are written to read-in actual pressure, rpm, stator-growth and rotor growth data and, later, to transfer these as appropriate loads/motions in the system-dynamic model. The transient dynamic model evaluates the various motions, clearances