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Sample records for annuloplasty rings experience

  1. 21 CFR 870.3800 - Annuloplasty ring.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Annuloplasty ring. 870.3800 Section 870.3800 Food... DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3800 Annuloplasty ring. (a) Identification. An annuloplasty ring is a rigid or flexible ring implanted around the mitral or tricuspid...

  2. 21 CFR 870.3800 - Annuloplasty ring.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Annuloplasty ring. 870.3800 Section 870.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Identification. An annuloplasty ring is a rigid or flexible ring implanted around the mitral or tricuspid...

  3. 21 CFR 870.3800 - Annuloplasty ring.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Annuloplasty ring. 870.3800 Section 870.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Identification. An annuloplasty ring is a rigid or flexible ring implanted around the mitral or tricuspid...

  4. 21 CFR 870.3800 - Annuloplasty ring.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Annuloplasty ring. 870.3800 Section 870.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3800 Annuloplasty ring....

  5. 21 CFR 870.3800 - Annuloplasty ring.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Annuloplasty ring. 870.3800 Section 870.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3800 Annuloplasty ring....

  6. Development of personalized annuloplasty rings: combination of CT images and CAD-CAM tools.

    PubMed

    Díaz Lantada, Andrés; Valle-Fernández, Raquel Del; Morgado, Pilar Lafont; Muñoz-García, Julio; Muñoz Sanz, José Luis; Munoz-Guijosa, Juan Manuel; Otero, Javier Echávarri

    2010-02-01

    Although the use of personalized annuloplasty rings manufactured for each patient according to the size and morphology of their valve complex could be beneficial for the treatment of mitral insufficiency, this possibility has been limited for reasons of time-lines and costs as well as for design and manufacturing difficulties, as has been the case with other personalized implant and prosthetic developments. However, the present quality of medical image capture equipment together with the benefits to be had from computer-aided design and manufacturing technologies (CAD-CAM) and the capabilities furnished by rapid prototyping technologies, present new opportunities for a personalized response to the development of implants and prostheses, the social impact of which could turn out to be highly positive. This paper sets out a personalized development of an annuloplasty ring based on the combined use of information from medical imaging, from CAD-CAM design programs and prototype manufacture using rapid prototyping technologies.

  7. Development of personalized annuloplasty rings: combination of CT images and CAD-CAM tools.

    PubMed

    Díaz Lantada, Andrés; Valle-Fernández, Raquel Del; Morgado, Pilar Lafont; Muñoz-García, Julio; Muñoz Sanz, José Luis; Munoz-Guijosa, Juan Manuel; Otero, Javier Echávarri

    2010-02-01

    Although the use of personalized annuloplasty rings manufactured for each patient according to the size and morphology of their valve complex could be beneficial for the treatment of mitral insufficiency, this possibility has been limited for reasons of time-lines and costs as well as for design and manufacturing difficulties, as has been the case with other personalized implant and prosthetic developments. However, the present quality of medical image capture equipment together with the benefits to be had from computer-aided design and manufacturing technologies (CAD-CAM) and the capabilities furnished by rapid prototyping technologies, present new opportunities for a personalized response to the development of implants and prostheses, the social impact of which could turn out to be highly positive. This paper sets out a personalized development of an annuloplasty ring based on the combined use of information from medical imaging, from CAD-CAM design programs and prototype manufacture using rapid prototyping technologies. PMID:19826955

  8. Biocompatibility and Systemic Safety of a Novel Implantable Annuloplasty Ring for the Treatment of Mitral Regurgitation in a Minipig Model.

    PubMed

    Ramot, Yuval; Rousselle, Serge D; Yellin, Nadav; Willenz, Udi; Sabag, Itai; Avner, Avi; Nyska, Abraham

    2016-07-01

    Prosthetic annuloplasty rings are a common treatment modality for mitral regurgitation, and recently, percutaneous implantation techniques have gained popularity due to their favorable safety profile. Although in common use, biocompatibility of annuloplasty rings has been reported only sparsely in the literature, and none of these reports used the percutaneous technique of implantation. We report on the biocompatibility and the systemic safety of a novel transcatheter mitral valve annuloplasty ring (AMEND™) in 6 minipigs. This device is composed of a nitinol tube surrounded by a braided polyethylene terephthalate fabric tube. The device produced no adverse inflammatory response, showing gradual integration between the metal ring and the fabric by normal host fibrocellular response, leading to complete neoendocardium coverage. There was no evidence for adverse reactions, rejection, or intolerance in the valvular structure. In 2 animals, hemopericardium resulted from the implantation procedure, leading to right-sided cardiac insufficiency with pulmonary edema and liver congestion. The findings reported herein can serve as a case study for the expected healing pathology reactions after implantation of transcatheter mitral valve annuloplasty rings.

  9. Development and experimental evaluation of a novel annuloplasty ring with a shape memory alloy core

    NASA Astrophysics Data System (ADS)

    Purser, Molly Ferris

    A novel annuloplasty ring with a shape memory alloy core has been developed to facilitate minimally invasive mitral valve repair. In its activated (austenitic) phase, this prototype ring provides comparable mechanical properties as commercial semi-rigid rings. In its pre-activated (martensitic) phase, this ring is flexible enough to be introduced through an 8 mm trocar and easily manipulated with robotic instruments within the confines of a left atrial model. The core is constructed of 0.508 mm diameter NiTi, which is maintained below its M s temperature (24°C) during deployment and suturing. After suturing, the stiffener is heated to its Af temperature (37°C, normal human body temperature) enabling the NiTi to retain its optimal geometry and stiffness characteristics indefinitely. The NiTi core is shape set in a furnace to the appropriate size and optimal geometry during fabrication. The ring is cooled in a saline bath prior to surgery, making it compliant and easy to manipulate. Evaluation of the ring included mechanical testing, robotic evaluation, static pressure testing, dynamic flow testing and fatigue testing. Experimental results suggest that the NiTi core ring could be a viable alternative to flexible bands in robot-assisted mitral valve repair.

  10. A Novel Shape Memory Alloy Annuloplasty Ring for Minimally Invasive Surgery: Design, Fabrication, and Evaluation

    PubMed Central

    Purser, Molly F.; Richards, Andrew L.; Cook, Richard C.; Osborne, Jason A.; Cormier, Denis R.; Buckner, Gregory D.

    2013-01-01

    A novel annuloplasty ring with a shape memory alloy core has been developed to facilitate minimally invasive mitral valve repair. In its activated (austenitic) phase, this prototype ring has comparable mechanical properties to commercial semi-rigid rings. In its pre-activated (martensitic) phase, this ring is flexible enough to be introduced through an 8-mm trocar and easily manipulated with robotic instruments within the confines of a left atrial model. The core is constructed of 0.50 mm diameter NiTi, which is maintained below its martensitic transition temperature (24 °C) during deployment and suturing. After suturing, the ring is heated above its austenitic transition temperature (37 °C, normal human body temperature) enabling the NiTi core to attain its optimal geometry and stiffness characteristics indefinitely. This article summarizes the design, fabrication, and evaluation of this prototype ring. Experimental results suggest that the NiTi core ring could be a viable alternative to flexible bands in robot-assisted minimally invasive mitral valve repair. PMID:20652747

  11. Comparison of the novel Medtentia double helix mitral annuloplasty system with the Carpentier-Edwards Physio annuloplasty ring: morphological and functional long-term outcome in a mitral valve insufficiency sheep model

    PubMed Central

    2013-01-01

    Background The prevalence of mitral regurgitation in cardiac diseases requires annuloplasty systems that can be implanted without excessive patient burden. This study was designed to examine the morphological and functional outcome of a new double helix mitral annuloplasty ring in an ovine model in comparison to the classical Carpentier-Edwards (CE) annuloplasty ring as measured by reduction of mitral regurgitation and tissue integration. The Medtentia annuloplasty ring (MAR) is a helical device that is rotated into the annulus self-restoring the valve geometry, enabling a faster fixation without the need of elaborate repair of the valve geometry. The ventricular part of the helical ring encircles the valve chords. Methods Twenty adult sheep were overpaced until 2+ level mitral valve regurgitation was achieved. Seven animals per group received either the MAR or the CE ring. Implantation was performed on-pump in a beating heart through the left atrial appendix. The animals were sacrificed 3.6 ± 0.3 months after surgery following an echocardiography for assessing mitral regurgitation as primary endpoint. The annuloplasty rings with surrounding tissue were harvested for histological analyses as secondary endpoints. The remaining six sheep received the MAR system and were sampled seven, nine or 12 months after surgery. Results Implantation time (p < 0.01) and perfusion time (p < 0.001) as clinical secondary endpoints were significantly shorter in the MAR group. Echocardiography follow-ups showed sufficient valve function repair in nearly all animals with a normalization of the ventricle diameters in both groups (group difference: p = 0.147). The weights of the hearts did not differ significantly. Histology revealed adequately covered atrial annuloplasty rings with functional endothelium and lack of excessive granulation tissue or fibrosis in all specimens. The ventricular projections of the MAR systems encircling the chordae tendineae were not

  12. Safety and feasibility of a novel adjustable mitral annuloplasty ring: a multicentre European experience†

    PubMed Central

    Andreas, Martin; Doll, Nicolas; Livesey, Steve; Castella, Manuel; Kocher, Alfred; Casselman, Filip; Voth, Vladimir; Bannister, Christina; Encalada Palacios, Juan F.; Pereda, Daniel; Laufer, Guenther; Czesla, Markus

    2016-01-01

    OBJECTIVES Recurrent mitral regurgitation is a significant problem after mitral valve repair in patients with functional valve disease. We report the safety and feasibility of a novel adjustable mitral annuloplasty device that permits downsizing of the anterior–posterior diameter late after initial surgery. METHODS In this multicentre, non-randomized, observational register, patients with moderate or severe mitral regurgitation undergoing surgical mitral valve repair with the MiCardia EnCorSQ™ Mitral Valve Repair system were evaluated. Patient characteristics, operative specifications and results as well as postoperative follow-up were collected for all five centres. RESULTS Ninety-four patients with a median age of 71 (64–75) years (EuroSCORE II 6.7 ± 6.3; 66% male, 48% ischaemic MR, 37% dilated cardiomyopathy and 15% degenerative disease) were included. Operative mortality was 1% and the 1-year survival was 93%. Ring adjustment was attempted in 12 patients at a mean interval of 9 ± 6 months after surgery. In three of these attempts, a technical failure occurred. In 1 patient, mitral regurgitation was reduced two grades, in 2 patients mitral regurgitation was reduced one grade and in 6 patients, mitral regurgitation did not change significantly. The mean grade of mitral regurgitation changed from 2.9 ± 0.9 to 2.1 ± 0.7 (P = 0.02). Five patients were reoperated after 11 ± 9 months (Ring dehiscence: 2; failed adjustment: 3). CONCLUSION We conclude that this device may provide an additional treatment option in patients with functional mitral regurgitation, who are at risk for reoperation due to recurrent mitral regurgitation. Clinical results in this complex disease were ambiguous and patient selection seems to be a crucial step for this device. Further trials are required to estimate the clinical value of this therapeutic concept. PMID:25694471

  13. Mitral Valve Annuloplasty

    PubMed Central

    Rausch, Manuel K.; Bothe, Wolfgang; Kvitting, John-Peder Escobar; Swanson, Julia C.; Miller, D. Craig; Kuhl, Ellen

    2012-01-01

    Mitral valve annuloplasty is a common surgical technique used in the repair of a leaking valve by implanting an annuloplasty device. To enhance repair durability, these devices are designed to increase leaflet coaptation, while preserving the native annular shape and motion; however, the precise impact of device implantation on annular deformation, strain, and curvature is unknown. Here we quantify how three frequently used devices significantly impair native annular dynamics. In controlled in vivo experiments, we surgically implanted eleven flexible-incomplete, eleven semi-rigid-complete, and twelve rigid-complete devices around the mitral annuli of 34 sheep, each tagged with 16 equally-spaced tantalum markers. We recorded four-dimensional marker coordinates using biplane videofluoroscopy, first with device and then without, which were used to create mathematical models using piecewise cubic splines. Clinical metrics (characteristic anatomical distances) revealed significant global reduction in annular dynamics upon device implantation. Mechanical metrics (strain and curvature fields) explained this reduction via a local loss of anterior dilation and posterior contraction. Overall, all three devices unfavorably reduced annular dynamics. The flexible-incomplete device, however, preserved native annular dynamics to a larger extent than the complete devices. Heterogeneous strain and curvature profiles suggest the need for heterogeneous support, which may spawn more rational design of annuloplasty devices using design concepts of functionally graded materials. PMID:22037916

  14. The Jumping Ring Experiment

    ERIC Educational Resources Information Center

    Baylie, M.; Ford, P. J.; Mathlin, G. P.; Palmer, C.

    2009-01-01

    The jumping ring experiment has become central to liquid nitrogen shows given as part of the outreach and open day activities carried out within the University of Bath. The basic principles of the experiment are described as well as the effect of changing the geometry of the rings and their metallurgical state. In general, aluminium rings are…

  15. Transatrial Intrapericardial Tricuspid Annuloplasty

    PubMed Central

    Rogers, Toby; Ratnayaka, Kanishka; Sonmez, Merdim; Franson, Dominique N.; Schenke, William H.; Mazal, Jonathan R.; Kocaturk, Ozgur; Chen, Marcus Y.; Faranesh, Anthony Z.; Lederman, Robert J.

    2015-01-01

    OBJECTIVES This study sought to demonstrate transcatheter deployment of a circumferential device within the pericardial space to modify tricuspid annular dimensions interactively and to reduce functional tricuspid regurgitation (TR) in swine. BACKGROUND Functional TR is common and is associated with increased morbidity and mortality. There are no reported transcatheter tricuspid valve repairs. We describe a transcatheter extracardiac tricuspid annuloplasty device positioned in the pericardial space and delivered by puncture through the right atrial appendage. We demonstrate acute and chronic feasibility in swine. METHODS Transatrial intrapericardial tricuspid annuloplasty (TRAIPTA) was performed in 16 Yorkshire swine, including 4 with functional TR. Invasive hemodynamics and cardiac magnetic resonance imaging (MRI) were performed at baseline, immediately after annuloplasty and at follow-up. RESULTS Pericardial access via a right atrial appendage puncture was uncomplicated. In 9 naïve animals, tricuspid septal-lateral and anteroposterior dimensions, the annular area and perimeter, were reduced by 49%, 31%, 59%, and 24% (p < 0.001), respectively. Tricuspid leaflet coaptation length was increased by 53% (p < 0.001). Tricuspid geometric changes were maintained after 9.7 days (range, 7 to 14 days). Small effusions (mean, 46 ml) were observed immediately post-procedure but resolved completely at follow-up. In 4 animals with functional TR, severity of regurgitation by intracardiac echocardiography was reduced. CONCLUSIONS Transatrial intrapericardial tricuspid annuloplasty is a transcatheter extracardiac tricuspid valve repair performed by exiting the heart from within via a transatrial puncture. The geometry of the tricuspid annulus can interactively be modified to reduce severity of functional TR in an animal model. PMID:25703872

  16. Storage Ring EDM Experiments

    NASA Astrophysics Data System (ADS)

    Semertzidis, Yannis K.

    2016-04-01

    Dedicated storage ring electric dipole moment (EDM) methods show great promise advancing the sensitivity level by a couple orders of magnitude over currently planned hadronic EDM experiments. We describe the present status and recent updates of the field.

  17. Suture Forces in Undersized Mitral Annuloplasty: Novel Device and Measurements

    PubMed Central

    Siefert, Andrew; Pierce, Eric; Lee, Madonna; Jensen, Morten; Aoki, Chikashi; Takebayashi, Satoshi; Gorman, Robert; Gorman, Joseph; Yoganathan, Ajit

    2014-01-01

    Purpose: Demonstrate the first use of a novel technology for quantifying suture forces on annuloplasty rings to better understand the mechanisms of ring dehiscence. Description: Force transducers were developed, attached to a size 24 Physio™ ring, and implanted in the mitral annulus of an ovine animal. Ring suture forces were measured after implantation and for cardiac cycles reaching peak left ventricular pressures (LVP) of 100, 125, and 150 mmHg. Evaluation: After implanting the undersized ring to the flaccid annulus, the mean suture force was 2.0±0.6 N. During cyclic contraction, anterior ring suture forces were greater than posterior ring suture forces at peak LVPs of 100 mmHg (4.9±2.0 N vs. 2.1±1.1 N), 125 mmHg (5.4±2.3 N vs. 2.3±1.2 N), and 150 mmHg (5.7±2.4 N vs. 2.4±1.1 N). The largest force was 7.4 N at 150 mmHg. Conclusions: Preliminary results demonstrate trends in annuloplasty suture forces and their variation with location and LVP. Future studies will significantly contribute to clinical knowledge by elucidating the mechanisms of ring dehiscence while improving annuloplasty ring design and surgical repair techniques. PMID:24996707

  18. Saturn-Ring Simulation Experiment

    NASA Astrophysics Data System (ADS)

    Yokota, T.

    2005-05-01

    We were able to generate the ring form in the laboratory by using two components fine particle plasmas (Dust Plasmas). This experiment will show one of the mechanisms of outer planets rings. The missions of Pioneer-10, 11, Voyager 1 and 2 revealed that micron and sub-micron size grains distribute spatially and that the Saturn rings were composed of small size dust particles. Dust particles are always charged by the influences of surrounding gaseous plasmas and UV radiations from the sun, so these particles are in the state of fine particle plasmas (dust plasmas). These particles prevail not only the influence of gravitational force only but the influence of electric and/or magnetic fields. This situation is believed and Mendis, Goertz et. al. investigated the dynamics of particles by introducing the gravitation and electrodynamics (gravito-electrodynamics). The gravitational force affects the influences charged and uncharged particles, equally. Charged particles (electric charge Q) are affected by F=Q(E+VXB), where V is particle velocity. Outer planets such as Saturn have magnetic fields like as earth, and these magnetized planets rotate around axis. The electric fields appear near a rotating magnetized sphere by an unipolar induction. Unipolar induction field E is given by E= -(wXr)XB using magnetic moment M of magnetized sphere at angular velocity w in a conducting medium (plasma). Within equatorial plane, B= - M/r3 and B=B0R3/r3, where R is the radius of planet and r is the distance from the center of the planet. This fields can be written as E=Pm/2r2T, by using Pm=4pr3B and T=2pw. The simulating condition can write as follows; where suffix S and M mean Saturn and miniature sphere, respectively. The created ring was located in the outskirts of the point from two to three times of sphere radius, and its thickness was very thin, and fine particle seem to rotate slowly around the sphere in same direction as rotation of sphere. The condition for creation was best

  19. Revascularization alone or combined with suture annuloplasty for ischemic mitral regurgitation. Evaluation by color Doppler echocardiography.

    PubMed Central

    Czer, L S; Maurer, G; Bolger, A F; DeRobertis, M; Chaux, A; Matloff, J M

    1996-01-01

    To determine the effectiveness of revascularization alone or combined with mitral valve repair for ischemic mitral regurgitation, we performed color Doppler echocardiography intraoperatively before and after cardiopulmonary bypass in 49 patients (mean age, 70 +/- 9 years) with concomitant mitral regurgitation and coronary artery disease (triple vessel or left main in 88%; prior infarction in 90%). After revascularization alone (n = 25), the mitral annulus diameter (2.88 +/- 0.44 cm vs 2.88 +/- 0.44 cm), leaflet-to-annulus ratio (1.44 +/- 0.30 vs 1.44 +/- 0.29), and mitral regurgitation grade (1.7 +/- 0.9 vs 1.8 +/- 0.7) remained unchanged (p = NS, postpump vs prepump); mitral regurgitation decreased by 2 grades in only 1 patient (4%). After combined revascularization and mitral valve suture annuloplasty (Kay-Zubiate; n = 24), the annulus diameter decreased (to 2.57 +/- 0.45 cm from 3.11 +/- 0.43 cm), the leaflet-to-annulus ratio increased (to 1.46 +/- 0.25 from 1.20 +/- 0.21), and the mitral regurgitation grade decreased significantly (to 0.9 +/- 0.9 from 2.8 +/- 1.0) (p < 0.01); mitral regurgitation decreased by 2 grades or more (successful repair) in 75%. The origin of the jet correlated with the site of prior infarction (p < 0.05), being inferior in cases of posterior or inferior infarction (67%), and central or broad in cases of combined anterior and inferior infarction (70%). Despite a slightly higher 30-day mortality in the repair group (p = 0.10), there was no significant difference in survival between the 2 surgical groups at 5 years or 8 years. Therefore, in this study of patients with mitral regurgitation and coronary artery disease, reduction in regurgitation grade with revascularization alone was infrequent. Concomitant suture annuloplasty significantly reduced regurgitation by reestablishing a more normal relationship between the leaflet and annulus sizes. The failure rate after suture annuloplasty was 25%; alternative repair techniques such as ring

  20. Ringing load models verified against experiments

    SciTech Connect

    Krokstad, J.R.; Stansberg, C.T.

    1995-12-31

    What is believed to be the main reason for discrepancies between measured and simulated loads in previous studies has been assessed. One has focused on the balance between second- and third-order load components in relation to what is called ``fat body`` load correction. It is important to understand that the use of Morison strip theory in combination with second-order wave theory give rise to second- as well as third-order components in the horizontal force. A proper balance between second- and third-order components in horizontal force is regarded as the most central requirements for a sufficient accurate ringing load model in irregular sea. It is also verified that simulated second-order components are largely overpredicted both in regular and irregular seas. Nonslender diffraction effects are important to incorporate in the FNV formulation in order to reduce the simulated second-order component and to match experiments more closely. A sufficient accurate ringing simulation model with the use of simplified methods is shown to be within close reach. Some further development and experimental verification must however be performed in order to take non-slender effects into account.

  1. Efficacy of Coblation Annuloplasty in Discogenic Low Back Pain

    PubMed Central

    He, Liangliang; Hu, Xiangyu; Tang, Yuanzhang; Li, Xiuhua; Zheng, Shuyue; Ni, Jiaxiang

    2015-01-01

    Abstract In degenerative disc, the innervated outer annulus is confirmed to the major origin resulted in discogenic pain. To alleviate the discogenic pain, annuloplasty with electrothermal technology was proved to be effective, which mainly involves the thermal heating of the annulus to denature collagen fibers and denervate posterior annular nerve fibers. However, little is known that efficacy of annuloplasty with coblation technology in treating discogenic pain through directly interrupting nerves in outer annulus. The purpose of this study was to evaluate the clinical outcomes of coblation annuloplasty for the treatment of discogenic low back pain. In a clinical prospective observational study, 17 consecutive patients with discogenic low back pain underwent coblation annuloplasty under local anesthesia. Pain visual analogue scale (VAS) scores, patient responses stating significant (≥50%) pain relief, and modified MacNab criteria were adopted to evaluate the pain intensity, degree of pain relief, and functional status after 6 months of follow-up. The preoperative pain VAS score was 6.5 ± 0.8(95% confidence interval [CI] 6.1–6.9) and the pain VAS score decreased to 2.9 ± 1.6 (95% CI 2.1–3.8), 2.9 ± 1.7 (95% CI 2.1–3.8), 3.2 ± 1.6 (95% CI 2.4–4.1), 3.2 ± 1.7 (95% CI 2.4–4.2) at 1 week and 1, 3 and 6 month postoperatively, respectively. 12 (70.6%), 11 (64.7%), 10 (58.8%) and 10 (58.8%) of patients reported significant pain relief at 1 week and 1, 3 and 6 months postoperatively. At 1, 3, and 6 months postoperatively, the numbers of patients with “excellent” or “good” ratings were 13 (76.5%), 11 (64.7%), and 10 (58.8%) according to the modified MacNab criteria. No serious complications were observed. The finds show that coblation annuloplasty is an effective, safe, and less uncomfortable procedure in managing discogenic low back pain. PMID:25984672

  2. A Safe and Effective Modification of Thomson's Jumping Ring Experiment

    ERIC Educational Resources Information Center

    Waschke, Felix; Strunz, Andreas; Meyn, Jan-Peter

    2012-01-01

    The electrical circuit of the jumping ring experiment based on discharging a capacitor is optimized. The setup is scoop proof at 46 V and yet the ring jumps more than 9 m high. The setup is suitable for both lectures and student laboratory work in higher education. (Contains 1 table, 8 figures and 3 footnotes.)

  3. Slip ring experience in long duration space applications

    NASA Technical Reports Server (NTRS)

    Phinney, Damon D.

    1986-01-01

    Ball Aerospace experience with slip rings in space extends back to 1962. Over 40 multi-ring assemblies have been flown and continuous operating lifetimes greater than 8 years at up to 60 rpm have been demonstrated. Slip rings provide multi-channel transfer of electrical power and signals in assemblies that are small in size and weight, and low in cost. By use of multiple brushes and sufficient copper within the assembly, power transfer efficiency better than 99.95 percent for high voltage circuits can be achieved. A low slip ring failure rate based on actual space operation totalling billions of ring revolutions has been established. Well qualified suppliers who have been making slip rings for space use for over 25 years are available. It is hoped that the suspected problem in SEASAT will not be allowed to prejudice space system designer against these very useful mechanisms.

  4. Hemodynamics and annuloplasty in isolated mitral regurgitation in children.

    PubMed

    Sulayman, R; Mathew, R; Thilenius, O G; Replogle, R; Arcilla, R A

    1975-12-01

    Isolated mitral insufficiency in children is quantitated angiographically by comparing the stroke volumes of the right ventricle and left ventricle. The disease results in greater enlargement of the left atrium than of the left ventricle and is accompanied by a significant increase in left atrial "distensibility." Right and left heart pressures may be normal or may be increased; they tend to be elevated in the group with regurgitant fractions of over 50%. Annuloplasty results in marked clinical and hemodynamic improvement and may even be corrective.

  5. Technology and experiments of 42CrMo bearing ring forming based on casting ring blank

    NASA Astrophysics Data System (ADS)

    Li, Yongtang; Ju, Li; Qi, Huiping; Zhang, Feng; Chen, Guozhen; Wang, Mingli

    2014-03-01

    Bearing ring is the crucial component of bearing. With regard to such problems as material waste, low efficiency and high energy consumption in current process of producing large bearing ring, a new process named "casting-rolling compound forming technology" is researched by taking the typical 42CrMo slew bearing as object. Through theoretical analysis, the design criteria of the main casting-rolling forming parameters are put forward at first. Then the constitutive relationship model of as-cast 42CrMo steel and its mathematical model of dynamic recrystallization are obtained according to the results of the hot compression experiment. By a coupled thermal-mechanical finite element model for radial-axial rolling of bearing ring, the fraction of dynamic recrystallization is calculated and recrystallized grains size are predicated. Meanwhile, the effects of the initial rolling temperature and feed rate of idle roll on material microstructure evolution are analyzed. Finally, the industrial rolling experiment is designed and performed, based on the simulation results. In addition, mechanical and metallographic tests are conducted on rolled bearing ring to get the mechanical parameters and metallographic structure. The experimental data and results show that the mechanical properties of bearing ring produced by casting-rolling compound forming technology are up to industrial standard, and a qualified bearing ring can be successfully formed by employing this new technology. Through the study, a process of forming large bearing ring directly by using casting ring blank is obtained, which could provide an effective theoretical guidance for manufacturing large ring parts. It also has an edge in saving material, lowering energy and improving efficiency.

  6. Adjustable mitral annuloplasty for the surgical treatment of ischaemic mitral insufficiency.

    PubMed

    Czesla, Markus; Götte, Julia; Doll, Nicolas

    2013-01-01

    Presentation of the MiCardia enCorSQ annuloplasty device implantation technique for ischaemic mitral regurgitation including late-stage activation: exposure of mitral valve using video-assisted right lateral mini-thoracotomy, annuloplasty, tunnelling of permanently attached lead through the left atrial wall and subcutaneous implantation; and late activation: minor cut-down procedure for lead exposure, connection to proprietary energy source (MC-100 RF generator), echocardiography and fluoroscopy guidance, anterior-posterior diameter reduction of memory-shape alloy core annuloplasty device by raising the temperature a few degrees above body temperature. PMID:24413004

  7. Characterization of a new electrostatic storage ring for photofragmentation experiments

    SciTech Connect

    Pedersen, H. B. Svendsen, A.; Harbo, L. S.; Kiefer, H. V.; Kjeldsen, H.; Lammich, L.; Andersen, L. H.; Toker, Y.

    2015-06-15

    We describe the design of and the first commissioning experiments with a newly constructed electrostatic storage ring named SAPHIRA (Storage Ring in Aarhus for PHoton-Ion Reaction Analysis). With an intense beam of Cu{sup −} at 4 keV, the storage ring is characterized in terms of the stored ion beam decay rate, the longitudinal spreading of an injected ion bunch, as well as the direct measurements of the transverse spatial distributions under different conditions of storage. The ion storage stability in SAPHIRA was investigated systematically in a selected region of its electrical configuration space.

  8. Pion Production and Entropy Experiments at Storage Rings

    SciTech Connect

    Jakobsson, B.; CHIC Collaboration

    2000-12-31

    The perspective for future experiments with large detector systems at storage rings, operating in slow ramping mode, is discussed. Data from slow ramping proton-nucleus and heavy ion collision experiments with more modest detector systems, on entropy estimation and charged pion emission from the absolute threshold to the energy region dominated by delta production, are presented and discussed.

  9. The liquid metal slip ring experiment for the communications technology satellite

    NASA Technical Reports Server (NTRS)

    Lovell, R. R.

    1972-01-01

    The experiment is designed to demonstrate liquid metal slip ring (LMSR) performance in a space environment. An evaluation was made of the features of the LMSR where improvement in performance over conventional slip rings was expected. The primary measurements to be made in the experiment will allow a determination of the slip ring electrical resistance, between ring insulation and ring cleanliness.

  10. Cavity Ring down Spectroscopy Experiment for an Advanced Undergraduate Laboratory

    ERIC Educational Resources Information Center

    Stacewicz, T.; Wasylczyk, P.; Kowalczyk, P.; Semczuk, M.

    2007-01-01

    A simple experiment is described that permits advanced undergraduates to learn the principles and applications of the cavity ring down spectroscopy technique. The apparatus is used for measurements of low concentrations of NO[subscript 2] produced in air by an electric discharge. We present the setup, experimental procedure, data analysis and some…

  11. The status of the Storage Ring EDM experiment

    SciTech Connect

    Semertzidis, Yannis K.

    2009-12-17

    The status of the storage ring experiment capable of probing the proton and deuteron EDM at the 10{sup -29} e.cm level is presented here. At this level it will be sensitive to a new physics mass scale of {approx}300 TeV. If there is new physics at the LHC, it will be sensitive to 10{mu}rad CP-violating phase level making it the most sensitive experiment for CP-violation beyond the SM.

  12. Experiments on Diffusion Flame Structure of a Laminar Vortex Ring

    NASA Technical Reports Server (NTRS)

    Chen, Shin-Juh; Dahm, Werner J. A.

    1999-01-01

    The study of flame-vortex interactions provides one of the means to better understand turbulent combustion, and allows for canonical configurations that contain the fundamental elements found in turbulent flames, These include concentrated vorticity, entrainment and mixing, strain and nonequilibrium phenomena, diffusion and differential diffusion, partial premixing and diluent effects, and heat release effects. In flame- vortex configurations, these fundamental elements can be studied under more controlled conditions than is possible in direct investigations of turbulent flames. Since the paper of Marble, the problem of the flame-vortex interaction has received considerable attention theoretically, numerically and experimentally. Several configurations exist for study of the premixed flame/vortex ring interaction but more limited results have been obtained to date for the diffusion flame/vortex ring case. The setup of Chen and Dahm, which is conceptually similar to that of Karagozian and Manda and Karagozian, Suganuma and Strom where the ring is composed of fuel and air and combustion begins during the ring formation process, is used in the current study. However, it is essential to conduct the experiments in microgravity to remove the asymmetries caused by buoyancy and thus obtain highly symmetric and repeatable interactions. In previous studies it was found that the flame structure of the vortex ring was similar to that obtained analytically by Karagozian and Manda. Dilution of propane with nitrogen led mainly to a reduction in flame luminosities, flame burnout times were affected by both fuel volumes and amount of dilution, and a simple model of the burnout times was developed. In this paper, a discussion on reacting ring displacement and flame burnout time will be given, and the flame structures of vortex rings containing ethane and air will be compared to those of propane reacting in air.

  13. Thomson’s ring experiment with resonant LC circuit

    NASA Astrophysics Data System (ADS)

    Haidar, Sajjad

    2016-01-01

    Thomson’s jumping ring experiment is conducted using a low voltage (24 V) electronic circuit. A coil (L) is connected with a capacitor (C) in parallel and is driven at its resonant frequency to obtain a high current in the coil. A circuit sends current pulses to the LC tank circuit at around its resonant frequency. The oscillating current in the coil induces a voltage in a copper-loop on top of it. The induced current interacts with the radial part of the coil-magnetic field; the resulting force levitates the loop. In a separate coil, a ferrite core and a copper ring are used to demonstrate the jumping-ring effect. The levitation and the jumping effect can be controlled by changing the duty cycle and frequency. In this report simple formulae and approximations are used to calculate the levitating force on the loop.

  14. Recent experiments with ring Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Eckel, S.; Kumar, A.; Anderson, N. W.; Campbell, G. K.

    2016-05-01

    Here, we present three recent results of our experiments with ring-shaped 23 Na Bose-Einstein condensates. First, we present results of the effect of temperature on the decay of persistent currents in the presence of a local, stationary perturbation, or weak link. When the weak link rotates, it can drive transitions between quantized persistent current states in the ring, that form hysteresis loops whose size depends strongly on temperature. We find that our data does not fit with a simple model of thermal activation. Second, we present a new method to measure the quantized persistent current state of the ring in a minimally-destructive way. This technique uses phonons as probes of the background flow through the Doppler effect. Finally, we present a set of experiments designed to reproduce the horizon problem in the early universe. Supersonic expansion of the ring creates causally-disconnected regions of BEC whose phase evolves at different rates. When the expansion stops and these regions are allowed to recombine, they form topological excitations. These excitations can be predicted using a simple theory that shows excellent agreement with the data.

  15. Lifting posterior mitral annuloplasty for enhancing leaflet coaptation in mitral valve repair: midterm outcomes

    PubMed Central

    Song, Meong Gun; Shin, Je Kyoun; Chee, Hyun Keun; Kim, Jun Seok; Yang, Hyun Suk

    2015-01-01

    Background We evaluated the midterm outcomes of lifting posterior mitral annuloplasty for enhancing leaflet coaptation in mitral valve repair. Methods Between October 2007 and December 2012, 341 consecutive patients with significant mitral regurgitation underwent lifting posterior mitral annuloplasty using a specially designed fabric annuloplasty strip that lifts the middle portion of the posterior annulus. Associated procedures for mitral valve repairs, such as patch valvuloplasty for posterior leaflet prolapse (n=80), new chord placement for anterior leaflet prolapse (n=33), commissurotomy (n=29), and posterior leaflet extension (n=23), were performed in 141 patients (41.3%). Results Thirty-day mortality was 0.9%. Nine late deaths (2.6%) occurred. Mean overall survival at 5 years was 96.0%±1.1%. During the mean follow-up period of 38±17 months, six patients (1.8%) underwent valve-related reoperation (5-year freedom from valve-related reoperation, 98.1%±0.8%). At 5 years, mean freedom from recurrence of mitral regurgitation grade 3+ to 4+ (moderate to severe) was 95.1%±1.6%. The mean valve pressure gradient (PG) was 3.2±1.5 mmHg across all strip sizes at the time of follow-up. Conclusions Lifting posterior mitral annuloplasty using an innovative annuloplasty strip in mitral valve repair has a low rate of recurrent regurgitation or valve-related reoperation with rare relevant complications. PMID:26309826

  16. Ion ring experiments with applications to the compact toroid program

    SciTech Connect

    Schamiloglu, E.; Greenly, J.B.; Hammer, D.A.; Pedrow, P.D.; Sudan, R.N.

    1985-05-01

    We report here the status of the ion ring experimental program at Cornell. Ion rings having 3 x 10/sup 15/. 430 keV protons have been trapped in the Ion Ring Experiment (IREX) in a 0.8 T magnetic field. Trapping was achieved using a static downstream mirror and a fast (1.7 ..mu..sec rise time) gated upstream mirror. Ring protons were detectable for up to 4 ..mu..sec (about 50 times both the ion cyclotron period and the injection pulse duration). On LONGSHOT II, up to 1 kJ of less than or equal to 150 keV ions has been produced in 0.4 to 0.9 ..mu..sec pulses using an active anode plasma source as well as the standard surface flashover source. The LONGSHOT II beam will shortly be formed into a rotating proton layer and injected into a preformed (0.3 m diameter and 2.5 m long) Z-discharge plasma to study axial energy dissipation processes. This proton layer ultimately is to be combined with a compact toroid plasma.

  17. The VOrtex Ring Transit EXperiment (VORTEX) GAS project

    NASA Technical Reports Server (NTRS)

    Bilen, Sven G.; Langenderfer, Lynn S.; Jardon, Rebecca D.; Cutlip, Hansford H.; Kazerooni, Alexander C.; Thweatt, Amber L.; Lester, Joseph L.; Bernal, Luis P.

    1995-01-01

    Get Away Special (GAS) payload G-093, also called VORTEX (VOrtex Ring Transit EXperiment), is an investigation of the propagation of a vortex ring through a liquid-gas interface in microgravity. This process results in the formation of one or more liquid droplets similar to earth based liquid atomization systems. In the absence of gravity, surface tension effects dominate the drop formation process. The Shuttle's microgravity environment allows the study of the same fluid atomization processes as using a larger drop size than is possible on Earth. This enables detailed experimental studies of the complex flow processes encountered in liquid atomization systems. With VORTEX, deformations in both the vortex ring and the fluid surface will be measured closely for the first time in a parameters range that accurately resembles liquid atomization. The experimental apparatus will record images of the interactions for analysis after the payload has been returned to earth. The current design of the VORTEX payload consists of a fluid test cell with a vortex ring generator, digital imaging system, laser illumination system, computer based controller, batteries for payload power, and an array of housekeeping and payload monitoring sensors. It is a self-contained experiment and will be flown on board the Space Shuttle in a 5 cubic feet GAS canister. The VORTEX Project is entirely run by students at the University of Michigan but is overseen by a faculty advisor acting as the payload customer and the contact person with NASA. This paper summarizes both the technical and programmatic aspects of the VORTEX Project.

  18. Experiments on cauldron formation: A polygonal cauldron and ring fractures

    NASA Astrophysics Data System (ADS)

    Komuro, Hiroaki

    1987-03-01

    The sequence of formation of the Motojuku-type cauldron (Fujita et al., 1970) is summarized as follows: (1) doming due to ascent of a magma body; (2) development of normal faults which produce a polygonal cauldron; and (3) eruption of acidic to intermediate pyroclastic material. Model experiments on a scale of 1/200,000 reveal that ascent of the magma body, which was imitated by a ball of hardened putty, produced a polygonal cauldron composed of radial and concentrically arranged short fractures on the roof of a dome. No ring fractures were formed. This type of cauldron develops near the surface. On the other hand, emission of magma which was imitated by evaporation of a ball of dry ice in brittle powdered material, caused ring faults dipping outward and a circular cauldron without up- or downwarping. This type of cauldron develops upward from the magma body. The former model is equated to the Motojuku-type cauldron, and the latter model to the other types of cauldrons with ring fractures.

  19. SNS Ring Operational Experience and Power Ramp Up Status

    SciTech Connect

    Plum, Michael A

    2009-01-01

    The SNS Ring has now been operating for about 3.5 years, and our march continues to increase the beam power to the full design value of 1.4 MW. The Ring is a loss-limited machine, and in general the radioactivation levels are good, but there are some unanticipated hot spots that we are working to improve. High intensity collective effects such as space-charge and beam instability have had minimal impact on beam operations to date. The cross plane coupling issue in the ring to target beam transport line has been solved. We will also discuss the status of equipment upgrades in the high-energy beam transport beam line, the injection-dump beam transport line, the ring, and the ring-to-target beam transport line.

  20. Numerical experiments in ringing of offshore systems under viscous loads

    SciTech Connect

    Gurley, K.R.; Kareem, A.

    1996-12-31

    A phenomenon which has recently received much attention in offshore engineering is the ringing response of structures. This high frequency transient type response has been observed in nature, particularly in tension leg platforms (TLPs). Given the implications of this behavior on the fatigue life of tendons, it is important that it be considered for response analysis. Significant progress has been made in recent years in identifying the nonlinear mechanisms that induce ringing in complex offshore structural systems. This introductory study-uses a simple model to numerically demonstrates several of the more salient features that are commonly cited in current literature, and shows that viscous loads may result in inducing ringing type response of members under certain conditions. Ringing response in pitch due to viscous loading is simulated on a column piercing the surface, and the significant contributing force mechanisms are identified. System characteristics are altered to ameliorate the performance of these systems.

  1. Splendor in the Rings...as Seen by the Cassini Imaging Science Experiment

    NASA Astrophysics Data System (ADS)

    Porco, C.; Brahic, A.; Burns, J.; Dones, L.; Murray, C.; Spitale, J.; Tiscareno, M.; Charnoz, S.; Beurle, K.; Evans, M.

    2004-12-01

    Since Cassini's approach to Saturn began in early February 2004, the Imaging Science experiment has collected multi-spectral observations of Saturn's rings at intermediate phase angles, images designed to search for previously unseen satellites near and within the ring system, images of known ring-region satellites for the purposes of orbit refinement, and a striking set of images acquired immediately after Cassini was placed in orbit, as the spacecraft flew across the unilluminated side of the rings, and then again, after it crossed the ring plane onto the illuminated side. New ring structures and objects have been found in the vicinity of the F ring, orbits for these objects as well as the F ring have been determined, the phase/color behavior of the rings has been extended into new geometries, and the highest resolution images have revealed a variety of features -- some brand new, and some previously known but seen now in greater two-dimensional detail -- all created by the perturbations of moons, both external and internal to the rings. Some of these features indicate the presence of unseen moons in ring gaps; analysis of others will allow reliable measures of ring viscosity and masses for the perturbing bodies. These new results and others, as well as their implications, will be discussed.

  2. Efficacy of coblation annuloplasty in discogenic low back pain: a prospective observational study.

    PubMed

    He, Liangliang; Hu, Xiangyu; Tang, Yuanzhang; Li, Xiuhua; Zheng, Shuyue; Ni, Jiaxiang

    2015-05-01

    In degenerative disc, the innervated outer annulus is confirmed to the major origin resulted in discogenic pain. To alleviate the discogenic pain, annuloplasty with electrothermal technology was proved to be effective, which mainly involves the thermal heating of the annulus to denature collagen fibers and denervate posterior annular nerve fibers. However, little is known that efficacy of annuloplasty with coblation technology in treating discogenic pain through directly interrupting nerves in outer annulus.The purpose of this study was to evaluate the clinical outcomes of coblation annuloplasty for the treatment of discogenic low back pain.In a clinical prospective observational study, 17 consecutive patients with discogenic low back pain underwent coblation annuloplasty under local anesthesia. Pain visual analogue scale (VAS) scores, patient responses stating significant (≥50%) pain relief, and modified MacNab criteria were adopted to evaluate the pain intensity, degree of pain relief, and functional status after 6 months of follow-up.The preoperative pain VAS score was 6.5 ± 0.8(95% confidence interval [CI] 6.1-6.9) and the pain VAS score decreased to 2.9 ± 1.6 (95% CI 2.1-3.8), 2.9 ± 1.7 (95% CI 2.1-3.8), 3.2 ± 1.6 (95% CI 2.4-4.1), 3.2 ± 1.7 (95% CI 2.4-4.2) at 1 week and 1, 3 and 6 month postoperatively, respectively. 12 (70.6%), 11 (64.7%), 10 (58.8%) and 10 (58.8%) of patients reported significant pain relief at 1 week and 1, 3 and 6 months postoperatively. At 1, 3, and 6 months postoperatively, the numbers of patients with "excellent" or "good" ratings were 13 (76.5%), 11 (64.7%), and 10 (58.8%) according to the modified MacNab criteria. No serious complications were observed.The finds show that coblation annuloplasty is an effective, safe, and less uncomfortable procedure in managing discogenic low back pain.

  3. Experience with a high-brightness storage ring: the NSLS 750 MeV vuv ring

    SciTech Connect

    Galayda, J.

    1984-01-01

    The NSLS vuv ring is the first implementation of the proposals of R. Chasman and G.K. Green for a synchrotron radiation source with enhanced brightness: its lattice is a series of achromatic bends with two zero-gradient dipoles each, giving small damped emittance; and these bends are connected by straight sections with zero dispersion to accommodate wigglers and undulators without degrading the radiation damping properties of the ring. The virtues of the Chasman-Green lattice, its small betatron and synchrotron emittances, may be understood with some generality; e.g. the electron ..gamma..m/sub 0/c/sup 2/ energy and the number of achromatic bends M sets a lower limit on the betatron emittance of e/sub x/ > 7.7 x 10/sup -13/ ..gamma../sup 2//M meter-radians. There is strong interest in extrapolation of this type of lattice to 6 GeV and to 32 achromatic bends. The subject of this report is the progress toward achieving performance in the vuv ring limited by the radiation damping parameters optimized in its design. 14 refs., 4 figs., 1 tab.

  4. The liquid metal slip ring experiment for the Communications Technology Satellite.

    NASA Technical Reports Server (NTRS)

    Lovell, R. R.

    1972-01-01

    Description of an experiment designed to demonstrate liquid metal slip ring (LMSR) performance in a space environment. The experiment, based on currently developed LMSR technology, is to make possible an evaluation of those features of a LMSR where improvement in performance over conventional slip rings might be feasible. The experiment-prompting, potential LMSR advantages include: lower electrical noise, higher current capability, higher voltage capability, longer life, and small variation in friction torque.

  5. Right heart chamber geometry and tricuspid annulus morphology in patients undergoing mitral valve repair with and without tricuspid valve annuloplasty.

    PubMed

    Tamborini, Gloria; Fusini, Laura; Muratori, Manuela; Gripari, Paola; Ghulam Ali, Sarah; Fiorentini, Cesare; Pepi, Mauro

    2016-06-01

    According to current recommendations, patients could benefit from tricuspid valve (TV) annuloplasty at the time mitral valve (MV) surgery if tricuspid regurgitation is severe or if tricuspid annulus (TA) dilatation is present. Therefore, an accurate pre-operative echocardiographic study is mandatory for left but also for right cardiac structures. Aims of this study are to assess right atrial (RA), right ventricular (RV) and TA geometry and function in patients undergoing MV repair without or with TV annuloplasty. We studied 103 patients undergoing MV surgery without (G1: 54 cases) or with (G2: 49 cases) concomitant TV annuloplasty and 40 healthy subjects (NL) as controls. RA, RV and TA were evaluated by three-dimensional (3D) transthoracic echocardiography. Comparing the pathological to the NL group, TA parameters and 3D right chamber volumes were significantly larger. RA and RV ejection fraction and TA% reduction were lower in pathological versus NL, and in G2 versus G1. In pathological patients, TA area positively correlated to systolic pulmonary pressure and negatively with RV and RA ejection fraction. Patients undergoing MV surgery and TV annuloplasty had an increased TA dimensions and a more advanced remodeling of right heart chambers probably reflecting an advanced stage of the disease. PMID:26820739

  6. Dissociative recombination of ammonia clusters studied by storage ring experiments

    SciTech Connect

    Oejekull, J.; Andersson, P. U.; Naagaard, M. B.; Pettersson, J. B. C.; Neau, A.; Rosen, S.; Thomas, R. D.; Larsson, M.; Semaniak, J.; Oesterdahl, F.; Danared, H.; Kaellberg, A.; Ugglas, M. af.

    2006-11-21

    Dissociative recombination of ammonia cluster ions with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). The absolute cross sections for dissociative recombination of H{sup +}(NH{sub 3}){sub 2}, H{sup +}(NH{sub 3}){sub 3}, D{sup +}(ND{sub 3}){sub 2}, and D{sup +}(ND{sub 3}){sub 3} in the collision energy range of 0.001-27 eV are reported, and thermal rate coefficients for the temperature interval from 10 to 1000 K are calculated from the experimental data and compared with earlier results. The fragmentation patterns for the two ions H{sup +}(NH{sub 3}){sub 2} and D{sup +}(ND{sub 3}){sub 2} show no clear isotope effect. Dissociative recombination of X{sup +}(NX{sub 3}){sub 2} (X=H or D) is dominated by the product channels 2NX{sub 3}+X [0.95{+-}0.02 for H{sup +}(NH{sub 3}){sub 2} and 1.00{+-}0.02 for D{sup +}(ND{sub 3}){sub 2}]. Dissociative recombination of D{sup +}(ND{sub 3}){sub 3} is dominated by the channels yielding three N-containing fragments (0.95{+-}0.05)

  7. Ring-Closing Metathesis: An Advanced Guided-Inquiry Experiment for the Organic Laboratory

    ERIC Educational Resources Information Center

    Schepmann, Hala G.; Mynderse, Michelle

    2010-01-01

    The design and implementation of an advanced guided-inquiry experiment for the organic laboratory is described. Grubbs's second-generation catalyst is used to effect the ring-closing metathesis of diethyl diallylmalonate. The reaction is carried out under an inert atmosphere at room temperature and monitored by argentic TLC. The crude reaction is…

  8. The double electrostatic ion ring experiment: a unique cryogenic electrostatic storage ring for merged ion-beams studies.

    PubMed

    Thomas, R D; Schmidt, H T; Andler, G; Björkhage, M; Blom, M; Brännholm, L; Bäckström, E; Danared, H; Das, S; Haag, N; Halldén, P; Hellberg, F; Holm, A I S; Johansson, H A B; Källberg, A; Källersjö, G; Larsson, M; Leontein, S; Liljeby, L; Löfgren, P; Malm, B; Mannervik, S; Masuda, M; Misra, D; Orbán, A; Paál, A; Reinhed, P; Rensfelt, K-G; Rosén, S; Schmidt, K; Seitz, F; Simonsson, A; Weimer, J; Zettergren, H; Cederquist, H

    2011-06-01

    We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate "rings" and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology.

  9. Treatment of functional mitral regurgitation by percutaneous annuloplasty: results of the TITAN Trial

    PubMed Central

    Siminiak, Tomasz; Wu, Justina C.; Haude, Michael; Hoppe, Uta C.; Sadowski, Jerzy; Lipiecki, Janusz; Fajadet, Jean; Shah, Amil M.; Feldman, Ted; Kaye, David M.; Goldberg, Steven L.; Levy, Wayne C.; Solomon, Scott D.; Reuter, David G.

    2012-01-01

    Aims Functional mitral regurgitation (FMR) contributes to morbidity and mortality in heart failure (HF) patients. The aim of this study was to determine whether percutaneous mitral annuloplasty could safely and effectively reduce FMR and yield durable long-term clinical benefit. Methods and results The impact of mitral annuloplasty (Carillon Mitral Contour System) was evaluated in HF patients with at least moderate FMR. Patients in whom the device was placed then acutely recaptured for clinical reasons served as a comparator group. Quantitative measures of FMR, left ventricular (LV) dimensions, New York Heart Association (NYHA) class, 6 min walk distance (6MWD), and quality of life were assessed in both groups up to 12 months. Safety and key functional data were assessed in the implanted cohort up to 24 months. Thirty-six patients received a permanent implant; 17 had the device recaptured. The 30-day major adverse event rate was 1.9%. In contrast to the comparison group, the implanted cohort demonstrated significant reductions in FMR as represented by regurgitant volume [baseline 34.5 ±11.5 mL to 17.4 ±12.4 mL at 12 months (P < 0.001)]. There was a corresponding reduction in LV diastolic volume [baseline 208.5 ±62.0 mL to 178.9 ±48.0 mL at 12 months (P =0.015)] and systolic volume [baseline 151.8 ±57.1 mL to 120.7 ±43.2 mL at 12 months (P =0.015)], compared with progressive LV dilation in the comparator. The 6MWD markedly improved for the implanted patients by 102.5 ±164 m at 12 months (P =0.014) and 131.9 ±80 m at 24 months (P < 0.001). Conclusion Percutaneous reduction of FMR using a coronary sinus approach is associated with reverse LV remodelling. Significant clinical improvements persisted up to 24 months. PMID:22613584

  10. On the Absorber Thickness of Microcalorimetric Detectors in Experiments at Nuclear Storage Rings

    NASA Astrophysics Data System (ADS)

    Andrianov, V. A.; Kraft-Bermuth, S.; Scholz, P.

    2016-07-01

    Low-temperature calorimetric detectors are now successfully used in experiments on Lamb-Shift measurements at experimental storage rings. Strong Doppler broadening of the detected X-ray lines is a prominent feature of these experiments. Accordingly, an optimization procedure for the absorber thickness is proposed that considers the self-width of the X-ray detector line, the Doppler broadening, and the absorption efficiency, taking into account the possibility of the escape of secondary radiation. The optimum thickness for Sn-absorbers in this type of experiments is determined as 0.17 mm.

  11. Protonation energies of 1-5-ring polycyclic aromatic nitrogen heterocyclics: comparing experiment and theory.

    PubMed

    Wiseman, Alexander; Sims, Lacey A; Snead, Russell; Gronert, Scott; Maclagan, Robert G A R; Meot-Ner Mautner, Michael

    2015-01-01

    Polycyclic nitrogen heterocyclic compounds (PANHs) can be protonated in the gas phase in mass spectrometry, in solution in acidic and biological environments, and if present, in interstellar clouds. Intrinsic molecular effects on PANH basicities can be observed by their gas phase protonation thermochemistry. We determined the gas phase basicities/proton affinities (GBs/PAs) of prototype one-nitrogen, 3-5-ring PANH compounds of increasing sizes and polarizabilities by kinetic bracketing, using proton transfer reactions to reference bases. The experimental proton affinities increase from 1-ring (pyridine, 222.2); to 2-ring (quinoline, 227.8); to 3-5-ring compounds, 227-234 kcal mol(-1). We also calculated the GB/PA values at the M06-2X/6-311+G**//B3LYP/6-31g* level. The computed PAs agree, within the experimental uncertainty, with the experimental values anchored to the upper range of the NIST GB/PA database. Specifically, the computed PAs are smaller than the experimental values by 1.4 ± 0.9 kcal/mol for nonaromatic nitrogen reference bases and for 1-5-ring PANHs, independently of the number of rings, aromaticity, and molecular size. Therefore, a useful method to calculate proton affinities of PANH compounds can use M06-2X/6-311+G**//B3LYP/6-31g* computational PAs + 1.4 ± 0.9 kcal mol(-1). The agreement with experiment supports the NIST database within this accuracy, in the upper range up to 235 kcal mol(-1), even though there are no direct absolute experimental anchor points in this range. For astrochemical applications, the measured PAs allow calculating the energies of the (PANH)(+•) + H2 → (PANH)H(+) + H(•) reactions that may convert the radical ions to less reactive 11-electron ions. The reactions are endothermic or nearly thermoneutral for the 3-5-ring ions and would be very slow at low temperatures, allowing reactive (PANH)(+•) radical ions to persist in interstellar clouds.

  12. High Ringxiety: Attachment Anxiety Predicts Experiences of Phantom Cell Phone Ringing.

    PubMed

    Kruger, Daniel J; Djerf, Jaikob M

    2016-01-01

    Mobile cell phone users have reported experiencing ringing and/or vibrations associated with incoming calls and messages, only to find that no call or message had actually registered. We believe this phenomenon can be understood as a human signal detection issue, with potentially important influences from psychological attributes. We hypothesized that individuals higher in attachment anxiety would report more frequent phantom cell phone experiences, whereas individuals higher in attachment avoidance would report less frequent experiences. If these experiences are primarily psychologically related to attributes of interpersonal relationships, associations with attachment style should be stronger than for general sensation seeking. We also predicted that certain contexts would interact with attachment style to increase or decrease the likelihood of experiencing phantom cell phone calls and messages. Attachment anxiety directly predicted the frequency of phantom ringing and notification experiences, whereas attachment avoidance and sensation seeking did not directly predict frequency. Attachment anxiety and attachment avoidance interacted with contextual factors (expectations for a call or message and concerned about an issue that one may be contacted about) in the expected directions for predicting phantom cell phone experiences. PMID:26701188

  13. High Ringxiety: Attachment Anxiety Predicts Experiences of Phantom Cell Phone Ringing.

    PubMed

    Kruger, Daniel J; Djerf, Jaikob M

    2016-01-01

    Mobile cell phone users have reported experiencing ringing and/or vibrations associated with incoming calls and messages, only to find that no call or message had actually registered. We believe this phenomenon can be understood as a human signal detection issue, with potentially important influences from psychological attributes. We hypothesized that individuals higher in attachment anxiety would report more frequent phantom cell phone experiences, whereas individuals higher in attachment avoidance would report less frequent experiences. If these experiences are primarily psychologically related to attributes of interpersonal relationships, associations with attachment style should be stronger than for general sensation seeking. We also predicted that certain contexts would interact with attachment style to increase or decrease the likelihood of experiencing phantom cell phone calls and messages. Attachment anxiety directly predicted the frequency of phantom ringing and notification experiences, whereas attachment avoidance and sensation seeking did not directly predict frequency. Attachment anxiety and attachment avoidance interacted with contextual factors (expectations for a call or message and concerned about an issue that one may be contacted about) in the expected directions for predicting phantom cell phone experiences.

  14. Storage-ring experiments on dielectronic recombination at the interface of atomic and nuclear physics

    NASA Astrophysics Data System (ADS)

    Brandau, Carsten; Kozhuharov, Christophor; Lestinsky, Michael; Müller, Alfred; Schippers, Stefan; Stöhlker, Thomas

    2015-11-01

    A brief review about topical developments in the exploitation of the resonant electron-ion collision process of dielectronic recombination (DR) as a sensitive spectroscopic tool is given. The focus will be on DR storage-ring experiments of few-electron highly charged ions. Among others, the questions addressed in these studies cover diverse topics from the areas of strong-field quantum electrodynamics, of lifetime studies using DR resonances, and of nuclear physics. Examples from the storage rings CRYRING in Stockholm, TSR in Heidelberg, and ESR in Darmstadt are given. In addition, an overview is provided about the ongoing developments and future perspectives of DR collision spectroscopy at the upcoming Facility for Antiproton and Ion Research in Darmstadt, Germany.

  15. Commissioning and Early Operation Experience of the NSLS-II Storage Ring RF System

    SciTech Connect

    Gao, F.; Rose, J.; Cupolo, J.; Dilgen, T.; Rose, B.; Gash, W.; Ravindranath, V.; Yeddulla, M.; Papu, J.; Davila, P.; Holub, B.; Tagger, J.; Sikora, R.; Ramirez, G.; Kulpin, J.

    2015-05-03

    The National Synchrotron Light Source II (NSLS-II) is a 3 GeV electron X-ray user facility commissioned in 2014. The storage ring RF system, essential for replenishing energy loss per turn of the electrons, consists of digital low level RF controllers, 310 kW CW klystron transmitters, CESR-B type superconducting cavities, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system for beam current up to 200mA.

  16. Should Tricuspid Annuloplasty be Performed With Pulmonary Valve Replacement for Pulmonary Regurgitation in Repaired Tetralogy of Fallot?

    PubMed

    Kurkluoglu, Mustafa; John, Anitha S; Cross, Russell; Chung, David; Yerebakan, Can; Zurakowski, David; Jonas, Richard A; Sinha, Pranava

    2015-01-01

    Indications for prophylactic tricuspid annuloplasty in patients with pulmonary regurgitation (PR) after tetralogy of Fallot (TOF) repair are unclear and often extrapolated from acquired functional tricuspid regurgitation (TR) data in adults, where despite correction of primary left heart pathology, progressive tricuspid annular dilation is noted beyond a threshold diameter >4 cm (21 mm/m(2)). We hypothesized that unlike in adult functional TR, in pure volume-overload conditions such as patients with PR after TOF, the tricuspid valve size is likely to regress after pulmonary valve replacement (PVR). A total of 43 consecutive patients who underwent PVR from 2005 until 2012 at a single institution were retrospectively reviewed. Absolute and indexed tricuspid annulus diameters (TADs), tricuspid annulus Z-scores, grade of TR along with right ventricular size, and function indices were recorded before and after PVR. Preoperative and postoperative echocardiographic data were available in all patients. A higher tricuspid valve Z-score correlated with greater TR both preoperatively (P = 0.005) and postoperatively (P = 0.02). Overall reductions in the absolute and indexed TAD and tricuspid valve Z-scores were seen postoperatively, with greater absolute as well as percentage reduction seen with larger preoperative TAD index (P = 0.007) and higher tricuspid annulus Z-scores (P = 0.06). In pure volume-overload conditions such as patients with PR after TOF, reduction in the tricuspid valve size is seen after PVR. Concomitant tricuspid annuloplasty should not be considered based on tricuspid annular dilation alone. PMID:26686442

  17. Estimating the hydraulic conductivity of slowly permeable and swelling materials from single-ring experiments

    NASA Astrophysics Data System (ADS)

    GéRard-Marchant, P.; Angulo-Jaramillo, R.; Haverkamp, R.; Vauclin, M.; Groenevelt, P.; Elrick, D. E.

    1997-06-01

    The in situ determination of the field-saturated hydraulic conductivity of low-permeability porous materials is a major concern for both geotechnics and soil physics with regards to environmental protection or water resources management. Recent early-time single-ring infiltration experiments, involving sequential constant head and falling head conditions, allow its efficient estimation. Nevertheless, the theory on which the interpretation was based was still strictly valid to nondeformable soils and implicity relied on a particular form of the hydraulic conductivity-soil water pressure head relationship. This theory is now extended to deformable materials, without any restrictive hypothesis. A new concept, bulk sorptivity, which characterizes the solid phase movement, is introduced. Field experiments, conducted on two liners of swelling and slowly permeable materials, revealed that neglecting the soil deformation induces an underestimation of the actual coefficient of permeability of the soil.

  18. The soil apparent infiltrability observed with ponded infiltration experiment in a permanent grid of infiltration rings

    NASA Astrophysics Data System (ADS)

    Votrubova, Jana; Jelinkova, Vladimira; Nemcova, Renata; Tesar, Miroslav; Vogel, Tomas; Cislerova, Milena

    2010-05-01

    Since 2003, a study of spatial and temporal variability of the soil infiltration properties has been in progress at the experimental site Liz (Volynka headwater catchment, Sumava Mountains, southern Bohemia). For the soil type of the study area (sandy loam developed upon gneiss bedrock), a large spatial variability of soil hydraulic properties had been observed. Moreover, the infiltration process is strongly dominated by preferential flow, as demonstrated by the results of a dye-tracer experiment conducted in 2005. The present study is focused primarily on the temporal variability of the soil hydraulic conductivity. Additionally, the influence of the initial soil moisture conditions on the soil infiltrability is examined. For this purpose, 18 permanent infiltration rings were installed at a gently sloped grass-covered experimental plot (300 sq m). Using this set-up, the single-ring ponded infiltration experiments have been conducted annually. Since 2005, a procedure of repeating the same ponded infiltration experiments in two successive days has been implemented. As expected, the observed quasi-steady-state infiltration rates varied much among the infiltration points (the coefficient of variation of values measured in one set of experiments was typically between 0,5 and 1). Regarding the temporal development, independent variations at separate measuring points were overridden by a huge overall increase of the observed infiltration rates (the average detected steady-state infiltration rate changed from 600 cm/day in 2003 to 2300 cm/day in 2009). With regard to the impact of the initial soil moisture conditions, general decrease of the observed infiltration rates for the repeated infiltration was detected.

  19. The trigger system for the external target experiment in the HIRFL cooling storage ring

    NASA Astrophysics Data System (ADS)

    Li, Min; Zhao, Lei; Liu, Jin-Xin; Lu, Yi-Ming; Liu, Shu-Bin; An, Qi

    2016-08-01

    A trigger system was designed for the external target experiment in the Cooling Storage Ring (CSR) of the Heavy Ion Research Facility in Lanzhou (HIRFL). Considering that different detectors are scattered over a large area, the trigger system is designed based on a master-slave structure and fiber-based serial data transmission technique. The trigger logic is organized in hierarchies, and flexible reconfiguration of the trigger function is achieved based on command register access or overall field-programmable gate array (FPGA) logic on-line reconfiguration controlled by remote computers. We also conducted tests to confirm the function of the trigger electronics, and the results indicate that this trigger system works well. Supported by the National Natural Science Foundation of China (11079003), the Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N27), and the CAS Center for Excellence in Particle Physics (CCEPP).

  20. Beam dynamics in an ultra-low energy storage rings (review of existing facilities and feasibility studies for future experiments)

    NASA Astrophysics Data System (ADS)

    Papash, A. I.; Smirnov, A. V.; Welsch, C. P.

    2014-03-01

    Storage rings operating at ultra-low energies and in particular electrostatic storage rings have proven to be invaluable tools for atomic and molecular physics. Due to the mass independence of the electrostatic rigidity, these machines are able to store a wide range of different particles, from light ions to heavy singly charged bio-molecules. However, earlier measurements showed strong limitations on beam intensity, fast decay of ion current, reduced life time etc. The nature of these effects was not fully understood. Also a large variety of experiments in future generation ultra-low energy storage and decelerator facilities including in-ring collision studies with a reaction microscope require a comprehensive investigation of the physical processes involved into the operation of such rings. In this paper, we present review of non-linear and long term beam dynamics studies on example of the ELISA, AD Recycler, TSR and USR rings using the computer codes BETACOOL, OPERA-3D and MAD-X. The results from simulations were benchmarked against experimental data of beam losses in the ELISA storage ring. We showed that decay of beam intensity in ultra-low energy rings is mainly caused by ion losses on ring aperture due to multiple scattering on residual gas. Beam is lost on ring aperture due to small ring acceptance. Rate of beam losses increases at high intensities because of the intra-beam scattering effect adds to vacuum losses. Detailed investigations into the ion kinetics under consideration of the effects from electron cooling and multiple scattering of the beam on a supersonic gas jet target have been carried out as well. The life time, equilibrium momentum spread and equilibrium lateral spread during collisions with this internal gas jet target were estimated. In addition, the results from experiments at the TSR ring, where low intensity beam of CF+ ions at 93 keV/u has been shrunk to extremely small dimensions have been reproduced. Based on these simulations

  1. Early experience with reduction of displaced disruption of the pelvic ring using a pelvic reduction frame.

    PubMed

    Lefaivre, K A; Starr, A J; Barker, B P; Overturf, S; Reinert, C M

    2009-09-01

    We describe our early operative experience with a new pelvic reduction frame and the standard of reduction of fractures of the pelvic ring which we achieved in the first 35 consecutive patients, with 34 acute fractures and one nonunion. The pre-operative and immediate post-operative radiographs were measured, using two methods, to find the maximum radiological displacement of the fracture and the quality of the reduction according to the criteria of Tornetta and Matta. There were 19 vertical shear fractures and 16 compression injuries. The mean age of the patients was 33.5 years (10 to 59) and mean delay to surgery was 4.6 days (0 to 16) in the 34 acute injuries. The mean operative time in isolated procedures was 103.4 minutes (SD 6.5). All but one patient had iliosacral screws implanted, 18 had screws in the anterior column, six had plates at the symphysis pubis and 12 had anterior external fixators. The mean maximum horizontal or vertical displacement was improved from 30.8 mm (SD 2.7) to a mean of 7.1 mm (SD 0.7). The reduction was assessed as excellent in ten patients, good in 18, and fair in the remainder. There was no significant influence on the quality of the reduction caused by obesity (p = 0.34), the type of fracture (p = 0.41) or delay to surgery (p = 0.83). The frame was shown to be effective, allowing the surgeon to obtain a satisfactory reduction and fixation of acute displaced disruptions of the pelvic ring.

  2. Effect of Transcatheter Mitral Annuloplasty With the Cardioband Device on 3-Dimensional Geometry of the Mitral Annulus.

    PubMed

    Arsalan, Mani; Agricola, Eustachio; Alfieri, Ottavio; Baldus, Stephan; Colombo, Antonio; Filardo, Giovanni; Hammerstingl, Christophe; Huntgeburth, Michael; Kreidel, Felix; Kuck, Karl-Heinz; LaCanna, Giovanni; Messika-Zeitoun, David; Maisano, Francesco; Nickenig, Georg; Pollock, Benjamin D; Roberts, Bradley J; Vahanian, Alec; Grayburn, Paul A

    2016-09-01

    This study was performed to assess the acute intraprocedural effects of transcatheter direct mitral annuloplasty using the Cardioband device on 3-dimensional (3D) anatomy of the mitral annulus. Of 45 patients with functional mitral regurgitation (MR) enrolled in a single arm, multicenter, prospective trial, 22 had complete pre- and post-implant 3D transesophageal echocardiography (TEE) images stored in native data format that allowed off-line 3D reconstruction. Images with the highest volume rate and best image quality were selected for analysis. Multiple measurements of annular geometry were compared from baseline to post-implant using paired t tests with Bonferroni correction to account for multiple comparisons. The device was successfully implanted in all patients, and MR was reduced to moderate in 2 patients, mild in 17 patients, and trace in 3 patients after final device cinching. Compared with preprocedural TEE, postprocedural TEE showed statistically significantly reductions in annular circumference (137 ± 15 vs 128 ± 17 mm; p = 0.042), intercommissural distance (42.4 ± 4.3 vs 38.6 ± 4.4 mm; p = 0.029), anteroposterior distance (40.0 ± 5.4 vs 37.0 ± 5.7 mm; p = 0.025), and aortic-mitral angle (117 ± 8° vs 112 ± 8°; p = 0.032). This study demonstrates that transcatheter direct mitral annuloplasty with the Cardioband device results in acute remodeling of the mitral annulus with successful reduction of functional MR.

  3. Effects of soil aggregates on debris-flow mobilization: Results from ring-shear experiments

    USGS Publications Warehouse

    Iverson, Neal R.; Mann, Janet E.; Iverson, Richard M.

    2010-01-01

    Rates and styles of landslide motion are sensitive to pore-water pressure changes caused by changes in soil porosity accompanying shear deformation. Soil may either contract or dilate upon shearing, depending upon whether its initial porosity is greater or less, respectively, than a critical-state porosity attained after sufficiently high strain. We observed complications in this behavior, however, during rate-controlled (0.02 m s−1) ring-shear experiments conducted on naturally aggregated dense loamy sand at low confining stresses (10.6 and 40 kPa). The aggregated soil first dilated and then contracted to porosities less than initial values, whereas the same soil with its aggregates destroyed monotonically dilated. We infer that aggregates persisted initially during shear and caused dilation before their eventual breakdown enabled net contraction. An implication of this contraction, demonstrated in experiments in which initial soil porosity was varied, is that the value of porosity distinguishing initially contractive from dilative behavior can be significantly larger than the critical-state porosity, which develops only after disaggregation ceases at high strains. In addition, post-dilative contraction may produce excess pore pressures, thereby reducing frictional strength and facilitating debris-flow mobilization. We infer that results of triaxial tests, which generally produce strains at least a factor of ∼ 4 smaller than those we observed at the inception of post-dilative contraction, do not allow soil contraction to be ruled out as a mechanism for debris-flow mobilization in dense soils containing aggregates.

  4. An improved technique of expanding metal ring experiment under high explosive loading.

    PubMed

    Tang, Tiegang; Ren, Guowu; Guo, Zhaoliang; Li, Qingzhong

    2013-04-01

    An experimental technique for metal expanding ring subjected to high explosive loading is conducted to significantly improve the loading stability compared with the traditional setup of two-end detonator initiation. Aspects of the circuit design, experimental arrangement, and initiation principle are illustrated in great detail. In terms of this experimental platform, we examine the velocity response of an individual ring, which demonstrates the experimental reproducibility. Moreover, fragmentation of multiple rings stacked on a metal driver is discussed.

  5. Testing a new automated single ring infiltrometer for Beerkan infiltration experiments

    NASA Astrophysics Data System (ADS)

    Di Prima, Simone; Lassabatère, Laurent; Angulo-Jaramillo, Rafael; Bagarello, Vincenzo; Iovino, Massimo

    2015-04-01

    The Beerkan method along with BEST algorithms is an alternative technique to conventional laboratory or field measurements for rapid and low-cost estimation of soil hydraulic properties. The Beerkan method is simple to conduct but requires an operator to pour known volumes of water through the ring and can be time-consuming. To alleviate this need, a new cheap infiltrometer equipped with a data acquisition system, allowing automation of Beerkan infiltration experiments, was recently designed and is presented in a companion paper. Yet, it has never been tested against a wide range of experimental conditions (soils, initial water saturation, etc.). In this paper, we tested the automated infiltrometer with the aim to validate its applicability to the Beerkan infiltration experiment under several experimental circumstances. In addition, we assessed the accuracy of BEST methods on the data obtained with the infiltrometer for the estimation of saturated soil hydraulic conductivity and sorptivity. For this purpose, we used both analytically generated and real experimental data. The analytically generated data simulate infiltration experiments carried out with the infiltrometer on five contrasting soils from UNSODA database and different initial water contents. The total volume of water to be infiltrated and the volume increments are fixed by the infiltrometer characteristics. Then, inverse analysis of the analytically generated data was performed using the three available BEST algorithms to derive saturated soil hydraulic conductivity and sorptivity that were compared to the reference values. The results of the analytical assessment showed that the infiltrometer along with BEST methods could lead to accurate estimates in most cases thus validating the design of the studied infiltrometer and its combination with BEST algorithms. Some soils (mostly loam) and some hydric conditions (high initial water contents) may lead to misestimate soil properties or failure of BEST

  6. Recent results from the internal polarized deuterium target experiment at the electron storage ring VEPP-3

    SciTech Connect

    Rachek, I.A.; Arenhoevel, H.; Barkov, L.M.; Dmitriev, V.F.; Dyug, M.V.; Belostotsky, S.L.; Gilman, R.; Holt, R.J.; Isaeva, L.G.; de Jager, C.W.; Kinney, E.R.; Kowalczyk, R.S.; Lazarenko, B.A.; Loginov, A.Yu.; Mishnev, S.I.; Nelyubin, V.V.; Nikolenko, D.M.; Osipov, A.V.; Potterveld, D.H.; Shestakov, Yu.V.; Sidorov, A.A.; Stibunov, V.N.; Toporkov, D.K.; Vesnovsky, D.K.; Vikhrov, V.V.; de Vries, H.; Zevakov, S.A.

    2000-12-31

    The simplest nucleus, the deuteron, is being studied at the 2-GeV electron storage ring VEPP-3. The storage ring itself, the polarized atomic beam source, the storage cell, and the particle detectors (segmented CsI + NaI electron calorimeters and hadron scintillator hodoscopes) are briefly described. Preliminary results on T{sub 20} in elastic ed scattering are given.

  7. [Experiences with a Token Ring Network in blood bank administration of the Hannover medical university].

    PubMed

    Raufmann, W; Stangel, W

    1991-01-01

    The Token Ring Network is a Local Area Network of IBM. It is a very helpful tool for modulating working processes by personal computers. The Token Ring is a network of the third generation and constructed like a star net. The blood bank of the Medical University of Hannover (MHH) is using the Token Ring for the administration of blood storage and donors. Medical data of foreign laboratories are transmitted into the blood bank computer. During the last year, we had no difficulties working with this software tool in response time and data security and it seemed to us a very cheap opportunity for data integration and data collection on decentralized systems.

  8. NanoRocks: A Long-Term Microgravity Experiment to Stydy Planet Formation and Planetary Ring Particles

    NASA Astrophysics Data System (ADS)

    Brisset, J.; Colwell, J. E.; Dove, A.; Maukonen, D.; Brown, N.; Lai, K.; Hoover, B.

    2015-12-01

    We report on the results of the NanoRocks experiment on the International Space Station (ISS), which simulates collisions that occur in protoplanetary disks and planetary ring systems. A critical stage of the process of early planet formation is the growth of solid bodies from mm-sized chondrules and aggregates to km-sized planetesimals. To characterize the collision behavior of dust in protoplanetary conditions, experimental data is required, working hand in hand with models and numerical simulations. In addition, the collisional evolution of planetary rings takes place in the same collisional regime. The objective of the NanoRocks experiment is to study low-energy collisions of mm-sized particles of different shapes and materials. An aluminum tray (~8x8x2cm) divided into eight sample cells holding different types of particles gets shaken every 60 s providing particles with initial velocities of a few cm/s. In September 2014, NanoRocks reached ISS and 220 video files, each covering one shaking cycle, have already been downloaded from Station. The data analysis is focused on the dynamical evolution of the multi-particle systems and on the formation of cluster. We track the particles down to mean relative velocities less than 1 mm/s where we observe cluster formation. The mean velocity evolution after each shaking event allows for a determination of the mean coefficient of restitution for each particle set. These values can be used as input into protoplanetary disk and planetary rings simulations. In addition, the cluster analysis allows for a determination of the mean final cluster size and the average particle velocity of clustering onset. The size and shape of these particle clumps is crucial to understand the first stages of planet formation inside protoplanetary disks as well as many a feature of Saturn's rings. We report on the results from the ensemble of these collision experiments and discuss applications to planetesimal formation and planetary ring

  9. Facies distribution of ejecta in analog tephra rings from experiments with single and multiple subsurface explosions

    NASA Astrophysics Data System (ADS)

    Graettinger, A. H.; Valentine, G. A.; Sonder, I.; Ross, P.-S.; White, J. D. L.

    2015-08-01

    The volume, grain size, and depositional facies of material deposited outside an explosion crater, ejecta, are sensitive to the depth of the explosion, the explosion energy, and the presence or absence of a crater before the explosion. We detonate buried chemical explosives as an analog for discrete volcanic explosions in experiments to identify unique characteristics of proximal, medial, and distal ejecta facies and their distribution from a range of scaled depths in undisturbed and cratered ground. Ejecta are here discussed in terms of three facies: (1) proximal ejecta, which form a constructional landform around a crater; (2) medial ejecta, which form a continuous sheet deposit that thins much more gradually with distance; and (3) distal ejecta that are deposited as isolated clasts. The extent of proximal ejecta away from the crater, relative to crater size, is not sensitive to scaled depth, but the volume proportion of proximal ejecta to the total ejecta deposit is sensitive to the presence of a crater and scaled depth. Medial ejecta distribution and volume contributions are both sensitive to the presence of a crater and to scaled depth. Distal ejecta distance is dependent on scaled depth and the presence of a crater, while the volume proportion of distal ejecta is less sensitive to scaled depth or presence of a crater. Experimental facies and deposit structures inferred from observations of jet dynamics are used to suggest facies associations anticipated from eruptions dominated by explosions of different scaled depth configurations. We emphasize that significant differences in tephra ring deposits can result from the effects of scaled depth and preexisting craters on ejecta dynamics, and are not necessarily related to fundamental differences in explosion mechanisms or degree of magma fragmentation.

  10. Two-dimensional finite-element analyses of simulated rotor-fragment impacts against rings and beams compared with experiments

    NASA Technical Reports Server (NTRS)

    Stagliano, T. R.; Witmer, E. A.; Rodal, J. J. A.

    1979-01-01

    Finite element modeling alternatives as well as the utility and limitations of the two dimensional structural response computer code CIVM-JET 4B for predicting the transient, large deflection, elastic plastic, structural responses of two dimensional beam and/or ring structures which are subjected to rigid fragment impact were investigated. The applicability of the CIVM-JET 4B analysis and code for the prediction of steel containment ring response to impact by complex deformable fragments from a trihub burst of a T58 turbine rotor was studied. Dimensional analysis considerations were used in a parametric examination of data from engine rotor burst containment experiments and data from sphere beam impact experiments. The use of the CIVM-JET 4B computer code for making parametric structural response studies on both fragment-containment structure and fragment-deflector structure was illustrated. Modifications to the analysis/computation procedure were developed to alleviate restrictions.

  11. Initial report on stress-corrosion-cracking experiments using Zircaloy-4 spent fuel cladding C-rings

    SciTech Connect

    Smith, H.D.

    1988-09-01

    The Nevada Nuclear Waste Storage Investigations (NNWSI) Project is sponsoring C-ring stress corrosion cracking scoping experiments as a first step in evaluating the potential for stress corrosion cracking of spent fuel cladding in a potential tuff repository environment. The objective is to scope the approximate behavior so that more precise pressurized tube testing can be performed over an appropriate range of stress, without expanding the long-term effort needlessly. The experiment consists of stressing, by compression with a dead weight load, C-rings fabricated from spent fuel cladding exposed to an environment of Well J-13 water held at 90{degree}C. The results indicate that stress corrosion cracking occurs at the high stress levels employed in the experiments. The cladding C-rings, tested at 90% of the stress at which elastic behavior is obtained in these specimens, broke in 25 to 64 d when tested in water. This was about one third of the time required for control tests to break in air. This is apparently the first observation of stress corrosion under the test conditions of relatively low temperature, benign environment but very high stress. The 150 ksi test stress could be applied as a result of the particular specimen geometry. By comparison, the uniaxial tensile yield stress is about 100 to 120 ksi and the ultimate stress is about 150 ksi. When a general model that fits the high stress results is extrapolated to lower stress levels, it indicates that the C-rings in experiments now running at {approximately}80% of the yield strength should take 200 to 225 d to break. 21 refs., 24 figs., 5 tabs.

  12. Electron-ion merged-beam experiments at heavy-ion storage rings

    NASA Astrophysics Data System (ADS)

    Schippers, Stefan

    2015-05-01

    In the past two decades, the electron-ion merged-beams technique has extensively been exploited at heavy-ion storage rings equipped with electron coolers for spectroscopic studies of highly charged ions as well as for measuring absolute cross sections and rate coefficients for electron-ion recombination and electron-impact ionization of multiply charged atoms ions. Some recent results are highlighted and future perspectives are pointed out, in particular, in view of novel experimental possibilities at the FAIR facility in Darmstadt and at the Cryogenic Storage Ring at the Max-Planck-Institute for Nuclear Physics in Heidelberg.

  13. Bunch coalescing and bunch rotation in the Fermilab Main Ring: Operational experience and comparison with simulations

    SciTech Connect

    Martin, P.S.; Wildman, D.W.

    1988-07-01

    The Fermilab Tevatron I proton-antiproton collider project requires that the Fermilab Main Ring produce intense bunches of protons and antiprotons for injection into the Tevatron. The process of coalescing a small number of harmonic number h=1113 bunches into a single bunch by bunch-rotating in a lower harmonic rf system is described.The Main Ring is also required to extract onto the antiproton production target bunches with as narrow a time spread as possible. This operation is also discussed. The operation of the bunch coalescing and bunch rotation are compared with simulations using the computer program ESME. 2 refs., 8 figs.

  14. Early experience of the compression anastomosis ring (CARTM 27) in left-sided colon resection

    PubMed Central

    Lee, Jung-Yeon; Woo, Jin-Hee; Choi, Hong-Jo; Park, Ki-Jae; Roh, Young-Hoon; Kim, Ki-Han; Lee, Hak-Yoon

    2011-01-01

    AIM: To evaluate clinical validity of the compression anastomosis ring (CAR™ 27) anastomosis in left-sided colonic resection. METHODS: A non-randomized prospective data collection was performed for patients undergoing an elective left-sided colon resection, followed by an anastomosis using the CAR™ 27 between November 2009 and January 2011. Eligibility criteria of the use of the CAR™ 27 were anastomoses between the colon and at or above the intraperitoneal rectum. The primary short-term clinical endpoint, rate of anastomotic leakage, and other clinical outcomes, including intra- and postoperative complications, length of operation time and hospital stay, and the ring elimination time were evaluated. RESULTS: A total of 79 patients (male, 43; median age, 64 years) underwent an elective left-sided colon resection, followed by an anastomosis using the CAR™ 27. Colectomy was performed laparoscopically in 70 patients, in whom two patients converted to open procedure (2.9%). There was no surgical mortality. As an intraoperative complication, total disruption of the anastomosis occurred by premature enforced tension on the proximal segment of the anastomosis in one patient. The ring was removed and another new CAR™ 27 anastomosis was constructed. One patient with sigmoid colon cancer showed postoperative anastomotic leakage after 6 d postoperatively and temporary diverting ileostomy was performed. Exact date of expulsion of the ring could not be recorded because most patients were not aware that the ring had been expelled. No patients manifested clinical symptoms of anastomotic stricture. CONCLUSION: Short-term evaluation of the CAR™ 27 anastomosis in elective left colectomy suggested it to be a safe and efficacious alternative to the standard hand-sewn or stapling technique. PMID:22147979

  15. First atomic physics experiments with cooled stored ion beams at the Heidelberg heavy-ion ring TSR

    SciTech Connect

    Wolf, A.; Balykin, V.; Baumann, W.; Berger, J.; Bisoffi, G.; Blatt, P.; Blum, M.; Faulstich, A.; Friedrich, A.; Gerhard, M.; Geyer, C.; Grieser, M.; Grieser, R.; Habs, D.; Heyng, H.W.; Hochadel, B.; Holzer, B.; Huber, G.; Jaeschke, E.; Jung, M.; Karafillidis, A.; Kilgus, G.; Klein, R.; Kraemer, D.; Krause, P.; Krieg, M.; Kuehl, T.; Matl, K.; Mueller, A.; Music, M.; Neumann, R.; Neureither, G.; Ott, W.; Petrich, W.; Povh, B.; Repnow, R.; Schroeder, S.; Schuch, R.; Schwalm, D.; Sigray, P.; Steck, M.; Stokstad, R.; Szmola, E.; Wagner, M.; Wanner, B.; Welti, K.; Zwickler, S. Max-Planck-Institut fuer Kernphysik, Heidelberg Manne Siegbahn Institute , Stockholm Institut fuer Kernphysik, Universitaet Giessen, Institut fuer Physik, Universitaet Mainz Gesellschaft fuer Schwerionenforschung , Darmstadt (Fed

    1990-06-01

    An overview of atomic physics experiments at the heavy ion Test Storage Ring (TSR) is given. Highly charged ions up to fully stripped silicon have been stored at energies between 4 and 12 MeV/u. The enhancement of the beam intensity by stacking, the beam lifetime, and electron cooling of these ion beams are discussed. Radiative and state-selective dielectronic recombination rates of hydrogen-like oxygen ions with free electrons from the electron cooler were measured. Beam noise spectra are being investigated with regard to collective effects caused by the Coulomb interaction in the cold ion beams. Resonance fluorescence from stored single-charged ions was observed using tunable narrow-band lasers. First indications of laser cooling in a storage ring were seen.

  16. Using split-ring resonators to measure the electromagnetic properties of materials: An experiment for senior physics undergraduates

    NASA Astrophysics Data System (ADS)

    Bobowski, J. S.

    2013-12-01

    A spilt-ring resonator experiment suitable for senior physics undergraduates is described and demonstrated in detail. The apparatus consists of a conducting hollow cylinder with a narrow slit along its length and can be accurately modelled as a series LRC circuit. The resonance frequency and quality factor of the split-ring resonator are measured when the apparatus is suspended in air, submerged in water, and submerged in an aqueous solution of various concentrations of NaCl. The experimental results are used to extract the dielectric constant of water and to investigate the dependence of the resonator quality factor on the conductivity of the NaCl solution. The apparatus provides opportunities to experimentally examine radiative losses, complex permittivity, the electromagnetic skin depth, and cutoff frequencies of rf propagation in cylindrical waveguides, which are all concepts introduced in an undergraduate course in electrodynamics. To connect with current research, the use of split-ring resonators as a tool to precisely measure the electromagnetic properties of materials is emphasized.

  17. Finite element analysis of the biomechanical interaction between coronary sinus and proximal anchoring stent in coronary sinus annuloplasty

    PubMed Central

    Pham, Thuy; Deherrera, Milton; Sun, Wei

    2013-01-01

    Recent clinical studies of the percutaneous transvenous mitral annuloplasty (PTMA) devices have shown a short-term reduction of mitral regurgitation (MR) after implantation. However, adverse events associated with the devices such as compression and perforation of vessel branches, device migration and fracture were reported. In this study, a finite element analysis was performed to investigate the biomechanical interaction between the proximal anchor stent of a PTMA device and the coronary sinus (CS) vessel in three steps including i) the stent release and contact with the CS wall, ii) the axial pull at the stent connector and iii) the pressure inflation of the vessel wall. To investigate the impact of the material properties of tissues and stents on the interactive responses, the CS vessel was modeled with human and porcine material properties, and the proximal stent was modeled with two different Nitinol materials with one being stiffer than the other. The results indicated that the vessel wall stresses and contact forces imposed by the stents were much higher in human than porcine models. However, the mechanical differences induced by the two stent types were relatively small. The softer stent exhibited a better fatigue safety factor when deployed in the human model than in the porcine model. These results underscored the importance of the CS tissue mechanical properties. Higher vessel wall stress and stent radial force were obtained in human model than those in porcine model, which also brought up questions as to the validity of using porcine model to assess device mechanical function. The quantification of these biomechanical interactions can offer scientific insight into the development and optimization of PTMA device design. PMID:23405942

  18. [First experience of intrastromal ring segments insertion for correction of posttraumatic cicatricial corneal astigmatism].

    PubMed

    Neroev, V V; Gundorova, R A; Beliaev, D S; Petukhova, A B; Oganesian, O G; Penkina, A V

    2013-01-01

    The potential of MAGELLAN MAPPER corneal topographer in evaluation of corneal refraction in the early postoperative period after surgical debrigement of scleral and corneal penetrating wounds is shown. The accuracy of corneal topography is satisfactory and its results reproducible what makes the method suitable for evaluation of corneal refraction and follow-up in patients with penetrating wounds and scarring of sclera and cornea. The possibility of posttraumatic cicatricial astigmatism correction by insertion of Keraring intrastromal corneal ring segments (ICRS) using femtosecond surgical laser FEMTO LDV were studied. Results of cicatricial corneal astigmatism correction in early posttraumatic period are encouraging.

  19. Operating experience with high beam currents and transient beam loading in the SLC damping rings

    SciTech Connect

    Minty, M.G.; Akre, R.; Krejcik, P.; Siemann, R.H.

    1995-06-01

    During the 1994 SLC run the nominal operating intensity in the damping rings was raised from 3.5 {times} 10{sup 10} to greater than 4 {times} 10{sup 10} particles per bunch (ppb). Stricter regulation of rf system parameters was required to maintain stability of the rf system and particle beam. Improvements were made in the feedback loops which control the cavity amplitude and loading angles. Compensation for beam loading was also required to prevent klystron saturation during repetition rate changes. To minimize the effects of transient loading on the rf system, the gain of the direct rf feedback loop and the loading angles were optimized.

  20. Experiments with longitudinally polarized electrons in a storage ring using a siberian snake

    PubMed

    Poolman; Boersma; Harvey; Higinbotham; Passchier; Six; Alarcon; van Amersfoort PW; Bauer; Boer Rookhuizen H; van Den Brand JF; van Buuren LD; Bulten; Ent; Ferro-Luzzi; Geurts; Heimberg; de Jager CW; Klimin; Koop; Kroes; van Der Laan J; Luijckx; Lysenko; Militsyn; Nesterenko

    2000-04-24

    We report on first measurements with polarized electrons stored in a medium-energy ring and with a polarized internal target. Polarized electrons were injected at 442 MeV (653 MeV), and a partial (full) Siberian snake was employed to preserve the polarization. Longitudinal polarization at the interaction point and polarization lifetime of the stored electrons were determined with laser backscattering. Spin observables were measured for electrodisintegration of polarized 3He, with simultaneous detection of scattered electrons, protons, neutrons, deuterons, and 3He nuclei, over a large phase space. PMID:11019223

  1. Measurement of Ring Strain Using Butanols: A Physical Chemistry Lab Experiment

    ERIC Educational Resources Information Center

    Martin, William R.; Davidson, Ada S.; Ball, David W.

    2016-01-01

    In this article, a bomb calorimeter experiment and subsequent calculations aimed at determining the strain energy of the cyclobutane backbone are described. Students use several butanol isomers instead of the parent hydrocarbons, and they manipulate liquids instead of gases, which makes the experiment much easier to perform. Experiments show that…

  2. Recent experience with inductive insert at the proton storage ring (PSR)

    SciTech Connect

    Ng, K.-Y; Griffin, J. E.; Wildman, D.; Popovic, M.; Browman, A. A.; Fitzgerald, D. H.; Macek, R. J.; Plum, M. A.; Spickermann, T. J.

    2001-01-01

    In a Fermilab-Los Alamos collaboration, inductances constructed of ferrite cores sufficient to cancel a large fraction of the space charge potential-well distortion were installed in the Los Alamos Proton Storage Ring (PSR) as one means of raising the threshold for the two-stream e-p instability. When operating at higher intensities and with sufficient inductance added for full space-charge compensation, an unacceptable longitudinal self-bunching, microwavelike, instability was encountered. Heating the cores to N 130 C proved to be an effective cure, and was found to be a means for tuning the inductance over a limited but useful range. The heated inductors were an essential ingredient in achieving a record accumulation of 9.7 pC/pulse. An engineered version of the inductors is now installed for routine operation of the PSR. A summary of the inductor characteristics, theory of operation, experimental results, and interpretation will be presented.

  3. Assessing the role of oxygen on ring current formation and evolution through numerical experiments

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Liemohn, M. W.; Toth, G.; Yu Ganushkina, N.; Daldorff, L. K. S.

    2015-06-01

    We address the effect of ionospheric outflow and magnetospheric ion composition on the physical processes that control the development of the 5 August 2011 magnetic storm. Simulations with the Space Weather Modeling Framework are used to investigate the global dynamics and energization of ions throughout the magnetosphere during storm time, with a focus on the formation and evolution of the ring current. Simulations involving multifluid (with variable H+/O+ ratio in the inner magnetosphere) and single-fluid (with constant H+/O+ ratio in the inner magnetosphere) MHD for the global magnetosphere with inner boundary conditions set either by specifying a constant ion density or by physics-based calculations of the ion fluxes reveal that dynamical changes of the ion composition in the inner magnetosphere alter the total energy density of the magnetosphere, leading to variations in the magnetic field as well as particle drifts throughout the simulated domain. A low oxygen to hydrogen ratio and outflow resulting from a constant ion density boundary produced the most disturbed magnetosphere, leading to a stronger ring current but misses the timing of the storm development. Conversely, including a physics-based solution for the ionospheric outflow to the magnetosphere system leads to a reduction in the cross-polar cap potential (CPCP). The increased presence of oxygen in the inner magnetosphere affects the global magnetospheric structure and dynamics and brings the nightside reconnection point closer to the Earth. The combination of reduced CPCP together with the formation of the reconnection line closer to the Earth yields less adiabatic heating in the magnetotail and reduces the amount of energetic plasma that has access to the inner magnetosphere.

  4. Laparoscopic inguinal hernia repair in children using the percutaneous internal ring suturing technique – own experience

    PubMed Central

    Patkowski, Dariusz

    2014-01-01

    Introduction Percutaneous internal ring suturing (PIRS) is a method of laparoscopic herniorrhaphy, i.e. percutaneous closure of the internal inguinal ring under the control of a telescope placed in the umbilicus. Aim To evaluate the usefulness of the PIRS technique. Material and methods Fifty-five children (39 girls and 16 boys) underwent surgery using this method in our institution between 2008 and 2010. Results In 10 cases the presence of an open inguinal canal on the opposite side was also noted during surgery, and umbilical hernia was recognized in 2 patients. In 5 cases it was necessary to convert to the open surgery because of the inability to continue the laparoscopic procedure. In 1 case, male pseudohermaphroditism was diagnosed during surgery. Recurrent inguinal hernia required a conventional method of surgery in 1 child. Other children did not exhibit the characteristics of hernia recurrence. The inguinal canals were followed up with postoperative ultrasound examination in 29 children. In 23 children, the ultrasound examination showed no dilatation of the inguinal canal. In the other 6 children dilatation of the inguinal canal or the presence of fluid within the inguinal canal was observed during ultrasound. In 6 children symptoms such as swelling and soreness around the inguinal canal developed within 3 to 6 months after surgery. Conclusions Inguinal hernia surgery using the PIRS procedure is an alternative, effective, minimally invasive method of surgery. Visualization of the peritoneal cavity allows for detection of other abnormalities, as well as for performing other procedures during the same session (such as closing the contralateral inguinal canal or umbilical hernia surgery). PMID:24729810

  5. Experience with the biofragmentable anastomotic ring (BAR) in bowel preoperatively irradiated with 6000 rad

    SciTech Connect

    Croston, J.K.; Jacobs, D.M.; Kelly, P.H.; Feeney, D.A.; Johnston, G.R.; Strom, R.L.; Bubrick, M.P. )

    1990-03-01

    Previous studies from the authors' laboratory using the biodegradable anastomotic ring (BAR) have demonstrated the safety of this device in animals irradiated preoperatively with the equivalent of 5000 rad; sutured, stapled, and BAR anastomoses all had leak rates of 10 percent or less in this setting. This study was undertaken to assess the safety of the BAR after irradiation with the equivalent of 6000 rad. Thirteen mongrel dogs underwent preoperative irradiation to the rectum and rectosigmoid, receiving 6000 rad according to the nominal standard dose equation. After a three-week rest period, each dog underwent anterior resection of the rectosigmoid and anastomosis with the BAR. The anastomoses were evaluated for early and late healing and anastomotic leaks. The results were compared with previous data from the authors' laboratory using an identical model. Radiographic leaks were found in 7 of 10 sutured anastomoses, 8 of 10 stapled anastomoses, and 3 of 13 BAR anastomoses (P less than 0.01). Comparative clinical leaks were 5 of 10 for sutured, 5 of 10 for stapled, and 3 of 13 for BAR anastomoses. These data suggest that the BAR may offer added safety to an anastomosis after preoperative irradiation. Whether this effect is due to the atraumatic technique of placing the device, improved blood flow to the anastomotic margins, or other factors, is still underdetermined.

  6. The Analog Ring Sampler: a 1 GHz signal sampling for the DVCS experiment in Hall A at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Muñoz Camacho, Carlos

    2003-10-01

    The Deeply Virtual Compton Scattering (DVCS) experiment in Hall A at Jefferson Lab uses a 132-block PbF2 electromagnetic calorimeter to detect a high energy photon ( ˜1.5-3.5 GeV). In order to cope with pile-up events coming from a high rate background, a new acquisition system based on the Analog Ring Sampler (ARS) chip has been developed. It continuously samples a signal at 1 GHz in a ring of 128 capacitors. When validated by an external trigger, every sample is digitalized by 12-bit flash-ADCs. In order to reduce the amount of data to record, 128×12 bits per sampled signal (waveform), as well as the acquisition dead time, a dedicated calorimeter trigger module has been developed. The electronics logic of both ARS and trigger modules will be detailed and their performances discussed. A waveform reconstruction algorithm to recognize several pulses in the 128 ns time window will also be presented.

  7. Ring of Silence: African American Women's Experiences Related to Their Breasts and Breast Cancer Screening

    ERIC Educational Resources Information Center

    Thomas, Eileen

    2006-01-01

    The purpose of this study was to explore women's memories and feelings concerning their breasts and breast cancer screening experiences in relation to their current breast cancer screening behaviors. Twelve African American women shared stories that were generated in written narratives and individual interviews. Two core themes emerged from the…

  8. Quantitative two-dimensional measurement of oil-film thickness by laser-induced fluorescence in a piston-ring model experiment.

    PubMed

    Wigger, Stefan; Füßer, Hans-Jürgen; Fuhrmann, Daniel; Schulz, Christof; Kaiser, Sebastian A

    2016-01-10

    This paper describes advances in using laser-induced fluorescence of dyes for imaging the thickness of oil films in a rotating ring tribometer with optical access, an experiment representing a sliding piston ring in an internal combustion engine. A method for quantitative imaging of the oil-film thickness is developed that overcomes the main challenge, the accurate calibration of the detected fluorescence signal for film thicknesses in the micrometer range. The influence of the background material and its surface roughness is examined, and a method for flat-field correction is introduced. Experiments in the tribometer show that the method yields quantitative, physically plausible results, visualizing features with submicrometer thickness.

  9. Planetary rings

    SciTech Connect

    Greenberg, R.; Brahic, A.

    1984-01-01

    Among the topics discussed are the development history of planetary ring research, the view of planetary rings in astronomy and cosmology over the period 1600-1900, the characteristics of the ring systems of Saturn and Uranus, the ethereal rings of Jupiter and Saturn, dust-magnetosphere interactions, the effects of radiation forces on dust particles, the collisional interactions and physical nature of ring particles, transport effects due to particle erosion mechanisms, and collision-induced transport processes in planetary rings. Also discussed are planetary ring waves, ring particle dynamics in resonances, the dynamics of narrow rings, the origin and evolution of planetary rings, the solar nebula and planetary disk, future studies of the planetary rings by space probes, ground-based observatories and earth-orbiting satellites, and unsolved problems in planetary ring dynamics.

  10. Nobel Chemistry in the Laboratory: Synthesis of a Ruthenium Catalyst for Ring-Closing Olefin Metathesis--An Experiment for the Advanced Inorganic or Organic Laboratory

    ERIC Educational Resources Information Center

    Greco, George E.

    2007-01-01

    An experiment for the upper-level undergraduate laboratory is described in which students synthesize a ruthenium olefin metathesis catalyst, then use the catalyst to carry out the ring-closing metathesis of diethyl diallylmalonate. The olefin metathesis reaction was the subject of the 2005 Nobel Prize in chemistry. The catalyst chosen for this…

  11. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  12. Planetary rings

    NASA Technical Reports Server (NTRS)

    Cook, A. F.

    1980-01-01

    Observations of the Rings of Saturn from the Pioneer spacecraft, discovery of the Ring of Jupiter, ground based polarimetry of the Rings of Saturn and some theoretical studies may be combined to markedly advance our understanding of the Rings of Jupiter, Saturn and Uranus. In particular, narrow rings can be self-gravitatingly stable inside Roche's limit and outside another closer limit. They can be created from a satellite which evolves across its Roche limit either by inward tidal drift or by growth of the planet by accretion. These considerations suggest that Neptune may well be surrounded by one or more narrow rings like those of Uranus.

  13. Design, fabrication and characterization of multi-guard-ring furnished p+n-n+ silicon strip detectors for future HEP experiments

    NASA Astrophysics Data System (ADS)

    Lalwani, Kavita; Jain, Geetika; Dalal, Ranjeet; Ranjan, Kirti; Bhardwaj, Ashutosh

    2016-07-01

    Si detectors, in various configurations (strips and pixels), have been playing a key role in High Energy Physics (HEP) experiments due to their excellent vertexing and high precision tracking information. In future HEP experiments like upgrade of the Compact Muon Solenoid experiment (CMS) at the Large Hadron Collider (LHC), CERN and the proposed International Linear Collider (ILC), the Si tracking detectors will be operated in a very harsh radiation environment, which leads to both surface and bulk damage in Si detectors which in turn changes their electrical properties, i.e. change in the full depletion voltage, increase in the leakage current and decrease in the charge collection efficiency. In order to achieve the long term durability of Si-detectors in future HEP experiments, it is required to operate these detectors at very high reverse biases, beyond the full depletion voltage, thus requiring higher detector breakdown voltage. Delhi University (DU) is involved in the design, fabrication and characterization of multi-guard-ring furnished ac-coupled, single sided, p+n-n+ Si strip detectors for future HEP experiments. The design has been optimized using a two-dimensional numerical device simulation program (TCAD-Silvaco). The Si strip detectors are fabricated with eight-layers mask process using the planar fabrication technology by Bharat Electronic Lab (BEL), India. Further an electrical characterization set-up is established at DU to ensure the quality performance of fabricated Si strip detectors and test structures. In this work measurement results on non irradiated Si Strip detectors and test structures with multi-guard-rings using Current Voltage (IV) and Capacitance Voltage (CV) characterization set-ups are discussed. The effect of various design parameters, for example guard-ring spacing, number of guard-rings and metal overhang on breakdown voltage of test structures have been studied.

  14. Neptune's rings

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

  15. Vascular ring

    MedlinePlus

    ... with aberrant subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... accounts for less than 1% of all congenital heart problems. The condition occurs as often in males ...

  16. Quantitative two-dimensional measurement of oil-film thickness by laser-induced fluorescence in a piston-ring model experiment.

    PubMed

    Wigger, Stefan; Füßer, Hans-Jürgen; Fuhrmann, Daniel; Schulz, Christof; Kaiser, Sebastian A

    2016-01-10

    This paper describes advances in using laser-induced fluorescence of dyes for imaging the thickness of oil films in a rotating ring tribometer with optical access, an experiment representing a sliding piston ring in an internal combustion engine. A method for quantitative imaging of the oil-film thickness is developed that overcomes the main challenge, the accurate calibration of the detected fluorescence signal for film thicknesses in the micrometer range. The influence of the background material and its surface roughness is examined, and a method for flat-field correction is introduced. Experiments in the tribometer show that the method yields quantitative, physically plausible results, visualizing features with submicrometer thickness. PMID:26835762

  17. Analyses, simulations, and experiments on the performance of the token-based optical burst transport ring networks

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Wen, Gan; Wang, Hongxiang; Bai, Lin; Ji, Yuefeng

    2007-11-01

    In this paper, both numerical and simulated modeling techniques were applied to analyze the influence on the performance of the token-based Optical Burst Transport (OBT) ring networks caused by the parameters, such as the minimum and maximum burst length, the circumference of the ring, and so on. We first analyze the issue by numerical analysis in the case that each node has only one token. After that, we confirm the analytical results and made further researches in the case that each node has multiple tokens by simulated analysis. All the results show that to design a high-performance token-based OBT ring network, not only the common parameters, such as the number of nodes and wavelengths, and the circumference of the ring, but also the special parameters, such as the minimum and maximum burst length, and the offset time should be taken into account. Furthermore, a testbed of Three-node Token-based OBT ring network Using Fixed Transmitter and Tuneable Receiver (FTTR) is constructed. With it, the variations of the network performance caused by the maximum burst length are investigated.1

  18. Calculation of flow in the piston-cylinder-ring crevices of a homogeneous-charge engine and comparison with experiment

    SciTech Connect

    Kuo, T.W.; Sellnau, M.C.; Theobald, M.A.; Jones, J.D.

    1989-01-01

    A crevice-flow model that had been published in the literature was reconstructed and used to calculate flow in the crevices between the piston, the cylinder, and the rings in a homogeneous-charge engine. The code was then modified to run interactively with a more sophisticated ring-friction model developed previously for calculation of the film thickness of lubricating oil on the cylinder liner. This paper discusses the accuracy of this crevice-flow model evaluated with engine-blowby data taken from tests on a multicylinder engine.

  19. DC-Powered Jumping Ring

    ERIC Educational Resources Information Center

    Jeffery, Rondo N.; Farhang, Amiri

    2016-01-01

    The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant…

  20. [Experience of the Pharmacotherapy against Appendix and Sigmoid Colon Signet Ring Cell Carcinoma with the Peritoneal Dissemination].

    PubMed

    Harada, Shingo; Tsuchida, Kazuhito; Shibuya, Taisuke; Doi, Yuki; Kikuchi, Akitomo; Mori, Koichi; Yabushita, Yasuhiro; Watanabe, Takuo; Murakami, Hitoshi; Hasegawa, Seiji; Fukushima, Tadao; Ike, Hideyuki; Nakayama, Takashi

    2015-10-01

    We report 2 cases of signet ring cell carcinoma of the appendix and colon. Case 1: A 61-year-old man was admitted for lower abdominal pain. Colonoscopy revealed an elevated lesion in the orifice of the appendix. Signet ring cell carcinoma was diagnosed on biopsy. The surgical findings showed multiple peritoneal dissemination nodules, while the primary tumor was unresectable owing to extensive invasion into the retroperitoneum. The histopathological findings were signet ring cell carcinoma, T4b (retroperitoneum), NX, P3, Stage Ⅳ. Although the patient received 14 courses of treatment with S-1 as postoperative chemotherapy, he died of his illness at 32 postoperative months. Case 2: A 76-year-old man was admitted for abdominal pain. Perforation of the lower gastrointestinal tract was diagnosed on abdominal CT, and an emergency operation was performed. The surgical findings demonstrated a large number of peritoneal dissemination nodules, cecal invasion of a sigmoid tumor, and perforation of the ascending colon. The primary tumor was thought to be unresectable, and the perforated segment was resected. The histopathological findings were signet ring cell carcinoma, T4b (cecum), NX, P3, Stage Ⅳ. Although 11 courses of treatment using FOLFIRI+Bev were administered as postoperative chemotherapy, the patient died of his illness at 26 postoperative months.

  1. Aromatic Ring Currents Illustrated--NMR Spectra of Tin(IV) Porphyrin Complexes. An Advanced Undergraduate Experiment.

    ERIC Educational Resources Information Center

    Arnold, Dennis P.

    1988-01-01

    Attempts to show that in the closed loops of cyclic structures the protons situated in conic regions above and below the ring will be shielded. Uses the diamagnetic and air stable octahedral tin(IV) complexes of porphyrins for study. Notes complexes crystallize easily and offer spectacular purple colors. (MVL)

  2. Frequency translation of light waves by propagation around an optical ring circuit containing a frequency shifter: I. Experiment.

    PubMed

    Shimizu, K; Horiguchi, T; Koyamada, Y

    1993-11-20

    A technique for the external frequency translation of light waves is reported. The technique permits the stepwise sweeping of an optical frequency over a wide range with high linearity with respect to time. The frequency translator is composed of an optical pulse modulator and an optical ring circuit containing an acousto-optic frequency shifter and an optical amplifier. The pulse launched into the ring circuit undergoes a constant frequency shift for each circulation around the circuit and the frequency can be translated to a considerable degree from that of the original input pulse. We report a stepwise frequency translation over approximately 68 GHz for a 1.5-µm light wave with a strictly constant frequency-sweep rate and an approximately constant intensity.

  3. Study of Mn dissolution from LiMn{sub 2}O{sub 4} spinel electrodes using rotating ring-disk collection experiments

    SciTech Connect

    Wang, Li-Fang; Ou, Chin-Ching; Striebel, Kathryn A.; Chen, Jenn-Shing

    2003-07-01

    The goal of this research was to measure Mn dissolution from a thin porous spinel LiMn{sub 2}O{sub 4} electrode by rotating ring-disk collection experiments. The amount of Mn dissolution from the spinel LiMn{sub 2}O{sub 4} electrode under various conditions was detected by potential step chronoamperometry. The concentration of dissolved Mn was found to increase with increasing cycle numbers and elevated temperature. The dissolved Mn was not dependent on disk rotation speed, which indicated that the Mn dissolution from the disk was under reaction control. The in situ monitoring of Mn dissolution from the spinel was carried out under various conditions. The ring currents exhibited maxima corresponding to the end-of-charge (EOC) and end-of-discharge (EOD), with the largest peak at EOC. The results suggest that the dissolution of Mn from spinel LiMn{sub 2}O{sub 4} occurs during charge/discharge cycling, especially in a charged state (at >4.1 V) and in a discharged state (at <3.1 V). The largest peak at EOC demonstrated that Mn dissolution took place mainly at the top of charge. At elevated temperatures, the ring cathodic currents were larger due to the increase of Mn dissolution rate.

  4. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  5. New Method for a Continuous Determination of the Spin Tune in Storage Rings and Implications for Precision Experiments

    NASA Astrophysics Data System (ADS)

    Eversmann, D.; Hejny, V.; Hinder, F.; Kacharava, A.; Pretz, J.; Rathmann, F.; Rosenthal, M.; Trinkel, F.; Andrianov, S.; Augustyniak, W.; Bagdasarian, Z.; Bai, M.; Bernreuther, W.; Bertelli, S.; Berz, M.; Bsaisou, J.; Chekmenev, S.; Chiladze, D.; Ciullo, G.; Contalbrigo, M.; de Vries, J.; Dymov, S.; Engels, R.; Esser, F. M.; Felden, O.; Gaisser, M.; Gebel, R.; Glückler, H.; Goldenbaum, F.; Grigoryev, K.; Grzonka, D.; Guidoboni, G.; Hanhart, C.; Heberling, D.; Hempelmann, N.; Hetzel, J.; Hipple, R.; Hölscher, D.; Ivanov, A.; Kamerdzhiev, V.; Kamys, B.; Keshelashvili, I.; Khoukaz, A.; Koop, I.; Krause, H.-J.; Krewald, S.; Kulikov, A.; Lehrach, A.; Lenisa, P.; Lomidze, N.; Lorentz, B.; Maanen, P.; Macharashvili, G.; Magiera, A.; Maier, R.; Makino, K.; Mariański, B.; Mchedlishvili, D.; Meißner, Ulf-G.; Mey, S.; Nass, A.; Natour, G.; Nikolaev, N.; Nioradze, M.; Nogga, A.; Nowakowski, K.; Pesce, A.; Prasuhn, D.; Ritman, J.; Rudy, Z.; Saleev, A.; Semertzidis, Y.; Senichev, Y.; Shmakova, V.; Silenko, A.; Slim, J.; Soltner, H.; Stahl, A.; Stassen, R.; Statera, M.; Stephenson, E.; Stockhorst, H.; Straatmann, H.; Ströher, H.; Tabidze, M.; Talman, R.; Thörngren Engblom, P.; Trzciński, A.; Uzikov, Yu.; Valdau, Yu.; Valetov, E.; Vassiliev, A.; Weidemann, C.; Wilkin, C.; Wirzba, A.; Wrońska, A.; Wüstner, P.; Zakrzewska, M.; Zuprański, P.; Zyuzin, D.; JEDI Collaboration

    2015-08-01

    A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune—defined as the number of spin precessions per turn—is given by νs=γ G (γ is the Lorentz factor, G the gyromagnetic anomaly). At 970 MeV /c , the deuteron spins coherently precess at a frequency of ≈120 kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the order 10-8, and to 1 ×10-10 for a continuous 100 s accelerator cycle. This renders the presented method a new precision tool for accelerator physics; controlling the spin motion of particles to high precision is mandatory, in particular, for the measurement of electric dipole moments of charged particles in a storage ring.

  6. New Method for a Continuous Determination of the Spin Tune in Storage Rings and Implications for Precision Experiments.

    PubMed

    Eversmann, D; Hejny, V; Hinder, F; Kacharava, A; Pretz, J; Rathmann, F; Rosenthal, M; Trinkel, F; Andrianov, S; Augustyniak, W; Bagdasarian, Z; Bai, M; Bernreuther, W; Bertelli, S; Berz, M; Bsaisou, J; Chekmenev, S; Chiladze, D; Ciullo, G; Contalbrigo, M; de Vries, J; Dymov, S; Engels, R; Esser, F M; Felden, O; Gaisser, M; Gebel, R; Glückler, H; Goldenbaum, F; Grigoryev, K; Grzonka, D; Guidoboni, G; Hanhart, C; Heberling, D; Hempelmann, N; Hetzel, J; Hipple, R; Hölscher, D; Ivanov, A; Kamerdzhiev, V; Kamys, B; Keshelashvili, I; Khoukaz, A; Koop, I; Krause, H-J; Krewald, S; Kulikov, A; Lehrach, A; Lenisa, P; Lomidze, N; Lorentz, B; Maanen, P; Macharashvili, G; Magiera, A; Maier, R; Makino, K; Mariański, B; Mchedlishvili, D; Meißner, Ulf-G; Mey, S; Nass, A; Natour, G; Nikolaev, N; Nioradze, M; Nogga, A; Nowakowski, K; Pesce, A; Prasuhn, D; Ritman, J; Rudy, Z; Saleev, A; Semertzidis, Y; Senichev, Y; Shmakova, V; Silenko, A; Slim, J; Soltner, H; Stahl, A; Stassen, R; Statera, M; Stephenson, E; Stockhorst, H; Straatmann, H; Ströher, H; Tabidze, M; Talman, R; Thörngren Engblom, P; Trzciński, A; Uzikov, Yu; Valdau, Yu; Valetov, E; Vassiliev, A; Weidemann, C; Wilkin, C; Wirzba, A; Wrońska, A; Wüstner, P; Zakrzewska, M; Zuprański, P; Zyuzin, D

    2015-08-28

    A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune-defined as the number of spin precessions per turn-is given by ν(s)=γG (γ is the Lorentz factor, G the gyromagnetic anomaly). At 970  MeV/c, the deuteron spins coherently precess at a frequency of ≈120  kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the order 10^{-8}, and to 1×10^{-10} for a continuous 100 s accelerator cycle. This renders the presented method a new precision tool for accelerator physics; controlling the spin motion of particles to high precision is mandatory, in particular, for the measurement of electric dipole moments of charged particles in a storage ring. PMID:26371657

  7. Jupiter's ring

    NASA Technical Reports Server (NTRS)

    1979-01-01

    First evidence of a ring around the planet Jupiter is seen in this photograph taken by Voyager 1 on March 4, 1979. The multiple exposure of the extremely thin faint ring appears as a broad light band crossing the center of the picture. The edge of the ring is 1,212,000 km from the spacecraft and 57,000 km from the visible cloud deck of Jupiter. The background stars look like broken hair pins because of spacecraft motion during the 11 minute 12 second exposure. The wavy motion of the star trails is due to the ultra-slow natural oscillation of the spacecraft (with a period of 78 seconds). The black dots are geometric calibration points in the camera. The ring thickness is estimated to be 30 km or less. The photograph was part of a sequence planned to search for such rings in Jupiter's equatorial plane. The ring has been invisible from Earth because of its thinness and its transparency when viewed at any angle except straight on. JPL manages and controls the Voyager Project for NASA's Office of Space Science.

  8. Development and construction of low-cracking high-performance concrete (LC-HPC) bridge decks: Free shrinkage tests, restrained ring tests, construction experience, and crack survey results

    NASA Astrophysics Data System (ADS)

    Yuan, Jiqiu

    2011-12-01

    The development, construction, and evaluation of low-cracking high-performance concrete (LC-HPC) bridge decks are described based on laboratory test results and experiences gained during the construction of 13 LC-HPC bridge decks in Kansas, along with another deck bid under the LC-HPC specifications but for which the owner did not enforce the specification. This study is divided into four parts covering (1) an evaluation of the free shrinkage properties of LC-HPC candidate mixtures, (2) an investigation of the relationship between the evaporable water content in the cement paste and the free shrinkage of concrete, (3) a study of the restrained shrinkage performance of concrete using restrained ring tests, and (4) a description of the construction and preliminary evaluation of LC-HPC and control bridge decks constructed in Kansas. The first portion of the study involves evaluating the effects of the duration of curing, fly ash, and a shrinkage reducing admixture (SRA) on the free-shrinkage characteristics of concrete mixtures. The results indicate that an increase of curing period reduces free shrinkage. With 7 days of curing, concretes containing fly ash as a partial replacement for cement exhibit higher free shrinkage than concretes with 100% portland cement. When the curing period is increased to 14, 28, and 56 days, the adverse effect of adding fly ash on free shrinkage is minimized and finally reversed. The addition of an SRA significantly reduces free shrinkage for both the 100% portland cement mixture and the mixture containing fly ash. The second portion of the study investigates the relationship between the evaporable water content in the cement paste and the free shrinkage of concrete. A linear relationship between free shrinkage and evaporable water content in the cement paste is observed. For a given mixture, specimens cured for a longer period contain less evaporable water and exhibit lower free shrinkage and less weight loss in the free shrinkage

  9. Ghostly Ring

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for poster version

    This image shows a ghostly ring extending seven light-years across around the corpse of a massive star. The collapsed star, called a magnetar, is located at the exact center of this image. NASA's Spitzer Space Telescope imaged the mysterious ring around magnetar SGR 1900+14 in infrared light. The magnetar itself is not visible in this image, as it has not been detected at infrared wavelengths (it has been seen in X-ray light).

    Magnetars are formed when a massive giant star ends its life in a supernova explosion, leaving behind a super dense neutron star with an incredibly strong magnetic field. The ring seen by Spitzer could not have formed during the original explosion, as any material as close to the star as the ring would have been disrupted by the supernova shock wave. Scientists suspect that the ring my actually be the edges of a bubble that was hollowed out by an explosive burst from the magnetar in 1998. The very bright region near the center of the image is a cluster of young stars, which may be illuminating the inner edge of the bubble, making it look like a ring in projection.

    This composite image was taken using all three of Spitzer's science instruments. The blue color represents 8-micron infrared light taken by the infrared array camera, green is 16-micron light from the infrared spectograph, and red is 24-micron radiation from the multiband imaging photometer.

  10. Making Molecular Borromean Rings

    ERIC Educational Resources Information Center

    Pentecost, Cari D.; Tangchaivang, Nichol; Cantrill, Stuart J.; Chichak, Kelly S.; Peters, Andrea J.; Stoddart, Fraser J.

    2007-01-01

    A procedure that requires seven 4-hour blocks of time to allow undergraduate students to prepare the molecular Borromean rings (BRs) on a gram-scale in 90% yield is described. The experiment would serve as a nice capstone project to culminate any comprehensive organic laboratory course and expose students to fundamental concepts, symmetry point…

  11. Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion.

    PubMed

    Cornejo, J M; Colombano, M; Doménech, J; Block, M; Delahaye, P; Rodríguez, D

    2015-10-01

    A special ion trap was initially built up to perform β-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single (40)Ca(+) ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on (40)Ca(+) ions, starting from large clouds and reaching single ion sensitivity. This new feature of the trap might be important also for other experiments with ions produced at radioactive ion beam facilities. In this publication, the trap and the laser system will be described, together with their performance with respect to laser cooling applied to large ion clouds down to a single ion.

  12. A season in Saturn's rings: Cycling, recycling and ring history

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Meinke, B. K.; Albers, N.; Sremcevic, M.

    2012-04-01

    Cassini experiments have watched Saturn's ring system evolve before our eyes. Images and occultations show changes and transient events. The rings are a dynamic and complex geophysical system, incompletely modeled as a single-phase fluid. Key Cassini observations: High resolution images show straw, propellers, embedded moonlets, and F ring objects. Multiple UVIS, RSS and VIMS occutlations indicate multimodal ringlet and edge structure, including free and forced modes along with stochastic perturbations that are most likely caused by nearby mass concentrations. Vertical excursions are evident at ring edges and in other perturbed regions. The rings are occasionally hit by meteorites that leave a signature that may last centuries; meteoritic dust pollutes the rings. Temperature, reflectance and transmission spectra are influenced by the dynamical state of the ring particles. Saturn's Equinox 2009: Oblique lighting exposed vertical structure and embedded objects. The rings were the coldest ever. Images inspired new occultation and spectral analysis that show abundant structure in the perturbed regions. The rings are more variable and complex than we had expected prior to this seasonal viewing geometry. Sub-kilometer structure in power spectral analysis: Wavelet analysis shows features in the strongest density waves and at the shepherded outer edge of the B ring. Edges are variable as shown by multiple occultations and occultations of double stars. F ring kittens: 25 features seen in the first 102 occultations show a weak correlation with Prometheus location. We interpret these features as temporary aggregations. Simulation results indicate that accretion must be enhanced to match the kittens' size distribution. Images show that Prometheus triggers the formation of transient objects. Propellers and ghosts: Occulations and images provide evidence for small moonlets in the A, B and C rings. These indicate accretion occurs inside the classical Roche limit. Implications

  13. Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion

    SciTech Connect

    Cornejo, J. M.; Colombano, M.; Doménech, J.; Rodríguez, D.; Block, M.; Delahaye, P.

    2015-10-15

    A special ion trap was initially built up to perform β-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single {sup 40}Ca{sup +} ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on {sup 40}Ca{sup +} ions, starting from large clouds and reaching single ion sensitivity. This new feature of the trap might be important also for other experiments with ions produced at radioactive ion beam facilities. In this publication, the trap and the laser system will be described, together with their performance with respect to laser cooling applied to large ion clouds down to a single ion.

  14. Measurement of the ratio of C3+ and O4+ ions produced by ECRIS to prepare a laser cooling experiment at storage rings

    NASA Astrophysics Data System (ADS)

    Zhu, X. L.; Wen, W. Q.; Ma, X.; Li, J. Y.; Feng, W. T.; Zhang, R. T.; Wang, Enliang; Yan, S.; Guo, D. L.; Hai, B.; Qian, D. B.; Zhang, P.; Xu, S.; Zhao, D. M.; Yang, J.; Zhang, D. C.; Li, B.; Gao, Y.; Huang, Z. K.; Wang, H. B.

    2014-11-01

    To prepare the upcoming laser cooling of relativistic C3+ ion beams at the experimental Cooler Storage Ring (CSRe), a novel experiment was performed using a reaction microscope to determine the ratio of C3+ ions in mixed ion beams of C3+ and O4+ that are produced by an Electron Cyclotron Resonance Ion Source (ECRIS). The mixed ion beams at an energy of 4 keV/u were directed to collide on a supersonic helium gas target. Using the single-electron capture channel and the coincidence technique, the fractions of C3+ and O4+ ions in the primary beam were obtained. Using different injection gases for ECRIS, including O2, CO, CO2, and CH4, at a fixed radio-frequency power of 300 W, the measured results showed that the fraction of C3+ ions was greater than 70% for the injection gases of CO and CO2. These measured results are very important and helpful for the upcoming laser cooling experiments.

  15. Ground Movement in SSRL Ring

    SciTech Connect

    Sunikumar, Nikita; /UCLA /SLAC

    2011-08-25

    Users of the Stanford Synchrotron Radiation Lightsource (SSRL) are being affected by diurnal motion of the synchrotron's storage ring, which undergoes structural changes due to outdoor temperature fluctuations. In order to minimize the effects of diurnal temperature fluctuations, especially on the vertical motion of the ring floor, scientists at SSRL tried three approaches: painting the storage ring white, covering the asphalt in the middle of the ring with highly reflective Mylar and installing Mylar on a portion of the ring roof and walls. Vertical motion in the storage ring is measured by a Hydrostatic Leveling System (HLS), which calculates the relative height of water in a pipe that extends around the ring. The 24-hr amplitude of the floor motion was determined using spectral analysis of HLS data, and the ratio of this amplitude before and after each experiment was used to quantitatively determine the efficacy of each approach. The results of this analysis showed that the Mylar did not have any significant effect on floor motion, although the whitewash project did yield a reduction in overall HLS variation of 15 percent. However, further analysis showed that the reduction can largely be attributed to a few local changes rather than an overall reduction in floor motion around the ring. Future work will consist of identifying and selectively insulating these local regions in order to find the driving force behind diurnal floor motion in the storage ring.

  16. The Phase Shift in the Jumping Ring

    ERIC Educational Resources Information Center

    Jeffery, Rondo N.; Amiri, Farhang

    2008-01-01

    The popular physics demonstration experiment known as Thomson's Jumping Ring (JR) has been variously explained as a simple example of Lenz's law, or as the result of a phase shift of the ring current relative to the induced emf. The failure of the first-quadrant Lenz's law explanation is shown by the time the ring takes to jump and by levitation.…

  17. Propellers in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Sremcevic, M.; Stewart, G. R.; Albers, N.; Esposito, L. W.

    2013-12-01

    Theoretical studies and simulations have demonstrated the effects caused by objects embedded in planetary rings. Even if the objects are too small to be directly observed, each creates a much larger gravitational imprint on the surrounding ring material. These strongly depend on the mass of the object and range from "S" like propeller-shaped structures for about 100m-sized icy bodies to the opening of circumferential gaps as in the case of the embedded moons Pan and Daphnis and their corresponding Encke and Keeler Gaps. Since the beginning of the Cassini mission many of these smaller objects (~<500m in size) have been indirectly identified in Saturn's A ring through their propeller signature in the images. Furthermore, recent Cassini observations indicate the possible existence of objects embedded even in Saturn's B and C ring. In this paper we present evidence for the existence of propellers in Saturn's B ring by combining data from Cassini Ultraviolet Imaging Spectrograph (UVIS) and Imaging Science Subsystem (ISS) experiments. We show evidence that B ring seems to harbor two distinct populations of propellers: "big" propellers covering tens of degrees in azimuth situated in the densest part of B ring, and "small" propellers in less dense inner B ring that are similar in size and shape to known A ring propellers. The population of "big" propellers is exemplified with a single object which is observed for 5 years of Cassini data. The object is seen as a very elongated bright stripe (40 degrees wide) in unlit Cassini images, and dark stripe in lit geometries. In total we report observing the feature in images at 18 different epochs between 2005 and 2010. In UVIS occultations we observe this feature as an optical depth depletion in 14 out of 93 occultation cuts at corrotating longitudes compatible with imaging data. Combining the available Cassini data we infer that the object is a partial gap located at r=112,921km embedded in the high optical depth region of the B

  18. Ringing wormholes

    SciTech Connect

    Konoplya, R.A.; Molina, C.

    2005-06-15

    We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (ringing) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.

  19. Computation and Experiment Reveal that the Ring-Rearrangement Metathesis of Himbert Cycloadducts Can Be Subject to Kinetic or Thermodynamic Control

    PubMed Central

    Lam, Jonathan K.; Pham, Hung V.; Houk, K. N.; Vanderwal, Christopher D.

    2013-01-01

    Unusual observations in the ring-rearrangement metathesis (RRM) of Himbert arene/allene cycloadducts to form fused polycylic lactams led to a more in-depth experimental study that yielded conflicting results. Differences in reactivity within related systems and unexpected changes in diastereoselectivity among other similar substrates were not readily explained on the basis of the experimental results. Computational investigations demonstrated substrate-dependent changes in reaction pathways (ring-opening metathesis/ring-closing metathesis [ROM/RCM] cascade vs. ring-closing metathesis/ring-opening metathesis [RCM/ROM] cascade). Furthermore, some reactions were judged to be under thermodynamic control, and others under kinetic control. The greater understanding of the most likely reaction pathways and their energetics provided a reasonable explanation for the previously irreconcilable results. PMID:24111571

  20. Reversible Seeding in Storage Rings

    SciTech Connect

    Ratner, Daniel; Chao, Alex; /SLAC

    2011-12-14

    We propose to generate steady-state microbunching in a storage ring with a reversible seeding scheme. High gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) are two promising methods for microbunching linac electron beams. Because both schemes increase the energy spread of the seeded beam, they cannot drive a coherent radiator turn-by-turn in a storage ring. However, reversing the seeding process following the radiator minimizes the impact on the electron beam and may allow coherent radiation at or near the storage ring repetition rate. In this paper we describe the general idea and outline a proof-of-principle experiment. Electron storage rings can drive high average power light sources, and free-electron lasers (FELs) are now producing coherent light sources of unprecedented peak brightness While there is active research towards high repetition rate FELs (for example, using energy recovery linacs), at present there are still no convenient accelerator-based sources of high repetition rate, coherent radiation. As an alternative avenue, we recently proposed to establish steady-state microbunching (SSMB) in a storage ring. By maintaining steady-state coherent microbunching at one point in the storage ring, the beam generates coherent radiation at or close to the repetition rate of the storage ring. In this paper, we propose a method of generating a microbunched beam in a storage ring by using reversible versions of linac seeding schemes.

  1. Rings from Close Encounters

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    Weve recently discovered narrow sets of rings around two minor planets orbiting in our solar system. How did these rings form? A new study shows that they could be a result of close encounters between the minor planets and giants like Jupiter or Neptune.Unexpected Ring SystemsPositions of the centaurs in our solar system (green). Giant planets (red), Jupiter trojans (grey), scattered disk objects (tan) and Kuiper belt objects (blue) are also shown. [WilyD]Centaurs are minor planets in our solar system that orbit between Jupiter and Neptune. These bodies of which there are roughly 44,000 with diameters larger than 1 km have dynamically unstable orbits that cross paths with those of one or more giant planets.Recent occultation observations of two centaurs, 10199 Chariklo and 2060 Chiron, revealed that these bodies both host narrow ring systems. Besides our four giant planets, Chariklo and Chiron are the only other bodies in the solar system known to have rings. But how did these rings form?Scientists have proposed several models, implicating collisions, disruption of a primordial satellite, or dusty outgassing. But a team of scientists led by Ryuki Hyodo (Paris Institute of Earth Physics, Kobe University) has recently proposed an alternative scenario: what if the rings were formed from partial disruption of the centaur itself, after it crossed just a little too close to a giant planet?Tidal Forces from a GiantHyodo and collaborators first used past studies of centaur orbits to estimate that roughly 10% of centaurs experience close encounters (passing within a distance of ~2x the planetary radius) with a giant planet during their million-year lifetime. The team then performed a series of simulations of close encounters between a giant planet and a differentiated centaur a body in which the rocky material has sunk to form a dense silicate core, surrounded by an icy mantle.Some snapshots of simulation outcomes (click for a closer look!) for different initial states of

  2. Water-rock interactions at >100°C in Enceladus inferred from hydrothermal experiments and silica particles in E-ring grains

    NASA Astrophysics Data System (ADS)

    Sekine, Y.; Shibuya, T.; Postberg, F.; Hsu, S.; Suzuki, K.; Kuwatani, T.; Masaki, Y.; Tachibana, S.

    2013-12-01

    A plume of vapour and water ice particles rich in sodium salts erupting from warm fractures near the south pole of Saturn's icy moon Enceladus suggest the presence of a liquid-water reservoir in the interior (Porco et al., 2005; Postberg et al., 2009; 2011). Cassini's findings of silica nanoparticles in the E-ring originating from the plumes imply active geochemistry involving hydrothermal water-rock interactions in Enceladus' interior (Hsu et al., 2013). However, the particular conditions of temperature and mineral compositions that can sustain the formation of silica inside Enceladus are yet unconstrained. In the present study, we conducted laboratory experiments and numerical calculations of hydrothermal reactions to understand the conditions of water-rock interactions occurring in Enceladus. In the experiments, we used aqueous solution of NH3 and NaHCO3 as starting solution to simulate Enceladus' ocean (Waite et al., 2009; Postberg et al., 2009; 2011). Olivine and orthopyroxene were used as starting minerals. The temperature and pressure conditions were 200-400°C and 400 bar, respectively. Our experimental results suggest that to achieve silica concentrations in the fluids sufficient for the formation of colloidal silica nanoparticles, hydrous silicates of Enceladus' core would be composed mainly of serpentine and saponite/talc, consistent with a chondritic composition of its rocky core. Fluid temperature needs to reach ≥ ~100°C. Our experimental results also suggest that decomposition of primordial NH3 to N2 would have been kinetically inhibited even at high temperatures. These results support the idea that deep hydrothermal circulation in a warm core drives hotspots in the ice mantle, possibly causing large tidal dissipation and melting beneath the south-pole region (Collins et al., 2007; Tobie et al., 2008). Furthermore, to achieve such high temperatures in Enceladus in geologically recent past, Enceladus might have formed in ~3-5 Myrs after the CAIs

  3. Interactions between unidirectional quantized vortex rings

    NASA Astrophysics Data System (ADS)

    Zhu, T.; Evans, M. L.; Brown, R. A.; Walmsley, P. M.; Golov, A. I.

    2016-08-01

    We have used the vortex filament method to numerically investigate the interactions between pairs of quantized vortex rings that are initially traveling in the same direction but with their axes offset by a variable impact parameter. The interaction of two circular rings of comparable radii produces outcomes that can be categorized into four regimes, dependent only on the impact parameter; the two rings can either miss each other on the inside or outside or reconnect leading to final states consisting of either one or two deformed rings. The fraction of energy that went into ring deformations and the transverse component of velocity of the rings are analyzed for each regime. We find that rings of very similar radius only reconnect for a very narrow range of the impact parameter, much smaller than would be expected from the geometrical cross-section alone. In contrast, when the radii of the rings are very different, the range of impact parameters producing a reconnection is close to the geometrical value. A second type of interaction considered is the collision of circular rings with a highly deformed ring. This type of interaction appears to be a productive mechanism for creating small vortex rings. The simulations are discussed in the context of experiments on colliding vortex rings and quantum turbulence in superfluid helium in the zero-temperature limit.

  4. Asymmetric dipolar ring

    DOEpatents

    Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

    2010-11-16

    A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

  5. Ion Rings for Magnetic Fusion

    SciTech Connect

    Greenly, John, B.

    2005-07-31

    This Final Technical Report presents the results of the program, Ion Rings for Magnetic Fusion, which was carried out under Department of Energy funding during the period August, 1993 to January, 2005. The central objective of the program was to study the properties of field-reversed configurations formed by ion rings. In order to reach this objective, our experimental program, called the Field-reversed Ion Ring Experiment, FIREX, undertook to develop an efficient, economical technology for the production of field-reversed ion rings. A field-reversed configuration (FRC) in which the azimuthal (field-reversing) current is carried by ions with gyro-radius comparable to the magnetic separatrix radius is called a field-reversed ion ring. A background plasma is required for charge neutralization of the ring, and this plasma will be confined within the ring's closed magnetic flux. Ion rings have long been of interest as the basis of compact magnetic fusion reactors, as the basis for a high-power accelerator for an inertial fusion driver, and for other applications of high power ion beams or plasmas of high energy density. Specifically, the FIREX program was intended to address the longstanding question of the contribution of large-orbit ions to the observed stability of experimental FRCs to the MHD tilt mode. Typical experimental FRCs with s {approx} 2-4, where s is the ratio of separatrix radius to ion gyro-radius, have been stable to tilting, but desired values for a fusion reactor, s > 20, should be unstable. The FIREX ring would consist of a plasma with large s for the background ions, but with s {approx} 1 for the ring ions. By varying the proportions of these two populations, the minimum proportion of large-orbit ions necessary for stability could be determined. The incorporation of large-orbit ions, perhaps by neutral-beam injection, into an FRC has been advanced for the purpose of stabilizing, heating, controlling angular momentum, and aiding the formation of a

  6. Growth Rings.

    ERIC Educational Resources Information Center

    Garmston, Robert J.

    1999-01-01

    In adaptive schools, working groups grow, develop, and learn from experience, becoming more effective as they go. Three premises about group development include the following: each group is unique, some groups mature, and attrition need not block development. Four guidelines for successful group meetings include decide who decides, define the…

  7. Researches on the Piston Ring

    NASA Technical Reports Server (NTRS)

    Ehihara, Keikiti

    1944-01-01

    In internal combustion engines, steam engines, air compressors, and so forth, the piston ring plays an important role. Especially, the recent development of Diesel engines which require a high compression pressure for their working, makes, nowadays, the packing action of the piston ring far more important than ever. Though a number of papers have been published in regard to researches on the problem of the piston ring, none has yet dealt with an exact measurement of pressure exerted on the cylinder wall at any given point of the ring. The only paper that can be traced on this subject so far is Mr. Nakagawa's report on the determination of the relative distribution of pressure on the cylinder wall, but the measuring method adopted therein appears to need further consideration. No exact idea has yet been obtained as to how the obturation of gas between the piston and cylinder, the frictional resistance of the piston, and the wear of the cylinder wall are affected by the intensity and the distribution of the radial pressure of the piston ring. Consequently, the author has endeavored, by employing an apparatus of his own invention, to get an exact determination of the pressure distribution of the piston ring. By means of a newly devised ring tester, to which piezoelectricity of quartz was applied, the distribution of the radial pressure of many sample rings on the market was accurately determined. Since many famous piston rings show very irregular pressure distribution, the author investigated and achieved a manufacturing process of the piston ring which will exert uniform pressure on the cylinder wall. Temperature effects on the configuration and on the mean spring power have also been studied. Further, the tests were performed to ascertain how the gas tightness of the piston ring may be affected by the number or spring power. The researches as to the frictional resistance between the piston ring and the cylinder wall were carried out, too. The procedure of study, and

  8. Future plans for the small isochronous ring

    SciTech Connect

    Eduard Pozdeyev

    2005-05-01

    The Small Isochronous Ring (SIR) has been operational at Michigan State University since December 2003. It has been used for experimental studies of the beam dynamics in high-intensity isochronous cyclotrons and synchrotrons at the transition energy. Operational experience with SIR has demonstrated that the ring can be successfully used to study space charge effects in accelerators. The low velocity of beam particles in the ring allowed longitudinal profile measurements with an accuracy that would be difficult to achieve in full-size accelerators. The experimental data obtained in the ring was used for validation of the multi-particle, space-charge codes CYCO and WARP3D. Encouraged by the success of SIR in the isochronous regime, we consider options for expanding the scope of the beam physics studied in the ring. In this paper, we outline possible future experiments and discuss required modifications of the ring optics and hardware.

  9. Stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  10. Actin Rings of Power.

    PubMed

    Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp

    2016-06-20

    Circular or ring-like actin structures play important roles in various developmental and physiological processes. Commonly, these rings are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger ring constriction. Actomyosin ring constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin ring-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin ring-like structures in various morphogenetic processes, shedding light on how those different rings have been adapted to fulfill their specific roles. PMID:27326928

  11. The rings of Saturn

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1978-01-01

    Consideration is given to the development of theories concerning the rings of Saturn. Particular attention is given to ring structure, noting its thinness, the separations between rings, and observed variations in brightness. Data gathered via infrared, radio and radar techniques are described in terms of ring particle composition and size. Hypotheses about ring origin and evolution are outlined, including the tidal disruption model, calculations of Saturn's gravitational contraction history, grazing, and meteoroid bombardment. Prospects for future observations of Saturn's rings are reviewed, such as the variation in their radar reflectivity as a function of the tilt of the ring plane.

  12. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    SciTech Connect

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  13. Radar Imaging of Saturn's Rings.

    NASA Astrophysics Data System (ADS)

    Nicholson, P. D.; Campbell, D. B.; French, R. G.; Margot, J.-L.; Black, G. J.; Nolan, M.

    2002-09-01

    The first radar echoes from Saturn's rings were obtained at a wavelength of 12.6 cm by Goldstein and Morris (1973). In October 1999 we used a frequency-stepped technique similar to that used in the mid-70s by Ostro etal. (1982) to make the first true radar images of the rings. In November 2000 and again in December 2001 we repeated this experiment, using the Arecibo S-band radar. With a pulse length of 70 msec, the range resolution of these data is 10,000 km; the Doppler spectra were processed to a frequency resolution of 2 kHz, corresponding to a radial resolution at the ring ansae of 2000 km. To date we have obtained images at ring opening angles B of -19.9, -23.6 and -25.9 deg. Images from all three years show a pronounced azimuthal asymmetry in the ring reflectivity, which is seen in both circular polarizations. The analogous phenomenon at visual wavelengths is ascribed to gravitational `wakes' generated by individual large ring particles, which are distorted by keplerian shear into elongated structures trailing at angles of 70 deg from the radial direction (Franklin and Colombo 1978). Such wakes are diagnostic of the rings' gravitational stability parameter, Q, and are expected to have characteristic length scales of 30-100 m in the A ring. To the radar, the rings appear brighter when the wakes are seen sideways, and fainter when they are viewed end-on. Fits of a numerical model by Salo and Karjalainen (1999) to our data show that the asymmetry is concentrated in the A ring, where its amplitude is 25% of the average reflectivity. This is twice the model prediction --- which is based on a dynamical simulation employing a realistic ring particle size distribution used as input to a Monte Carlo light scattering code --- and about three times the amplitude measured in HST images obtained at a wavelength of 439 nm and the same opening angle. The large amplitude of the radar asymmetry is difficult to reproduce with current models, although the phase of the asymmetry

  14. Design and experiment of 4H-SiC JBS diodes achieving a near-theoretical breakdown voltage with non-uniform floating limiting rings terminal

    NASA Astrophysics Data System (ADS)

    Yuan, Hao; Song, Qingwen; Tang, Xiaoyan; Zhang, Yimeng; Zhang, Yimen; Zhang, Yuming

    2016-09-01

    In this paper, a 4H-SiC Junction Barrier Schottky diode (JBS) with non-uniform floating limiting rings (FLRs) has been investigated and fabricated using n type 4H-SiC epitaxial layer with thickness of 31 μm and doping concentration of 3.3 × 1015 cm-3. According to the simulated results, the key parameters of a FLRs design to achieve a high voltage are the minimum space between two adjacent doped rings, spacing growth step and number of rings. The experimental results also show a great agreement with simulated results. Meanwhile, a near-ideal breakdown voltage of 3.7 kV was achieved, which yield around 95% of the parallel-plane breakdown voltage. The forward characteristics show that the fabricated JBS diodes have a forward current density of 210 A/cm2 at 3 V and a specific on-resistance (Rsp-on) of 7.58 mΩ cm2. Different FLRs parameters have no effect on the forward device performance.

  15. Optimizing Thomson's jumping ring

    NASA Astrophysics Data System (ADS)

    Tjossem, Paul J. H.; Brost, Elizabeth C.

    2011-04-01

    The height to which rings will jump in a Thomson jumping ring apparatus is the central question posed by this popular lecture demonstration. We develop a simple time-averaged inductive-phase-lag model for the dependence of the jump height on the ring material, its mass, and temperature and apply it to measurements of the jump height for a set of rings made by slicing copper and aluminum alloy pipe into varying lengths. The data confirm a peak jump height that grows, narrows, and shifts to smaller optimal mass when the rings are cooled to 77 K. The model explains the ratio of the cooled/warm jump heights for a given ring, the reduction in optimal mass as the ring is cooled, and the shape of the mass resonance. The ring that jumps the highest is found to have a characteristic resistance equal to the inductive reactance of the set of rings.

  16. Present and future of scientific bird ringing

    USGS Publications Warehouse

    Spina, F.; Tautin, J.; Adams, N.J.; Slotow, R.H.

    1999-01-01

    In 1999 scientific bird ringing will celebrate its first century of existence. Started mainly to investigate bird movements, bird ringing has become a much more flexible method to study different aspects of bird biology. Bird ringing can only be properly organised if an effective international co-operation exists. In Europe, this co-ordination is ensured by EURING, made of 35 national ringing centres; sister organisations exist in other parts of the world (like Africa, Australia, U.S. and Canada), sharing the same aims and problems. This RTD is mainly targeted to ornithologists involved with the co-ordination of bird ringing stations and national centres world-wide. Common aspects of the organisation of ringing activities, as well as of the potential ringing has and will have in the future in addressing major scientific questions in Ornithology will be taken into account. The advisability of setting up a standing committee on bird ringing within the IOC will be discussed, and the project of creating a world-wide organisation of ringing schemes in order to further improve communication and exchange of experiences will also be addressed. This new organisation would be formally founded in 1999, when an international conference organised by EURING to celebrate the first 100 years of bird ringing will be held in Denmark.

  17. Present and future of scientific bird ringing

    USGS Publications Warehouse

    Spina, F.; Tautin, J.; Adams, N.J.; Slotow, R.H.

    1998-01-01

    In 1999 scientific bird ringing will celebrate its first century of existence. Started mainly to investigate bird movements, bird ringing has become a much more flexible method to study different aspects of bird biology. Bird ringing can only be properly organised if an effective international co-operation exists. In Europe, this co-ordination is ensured by EURING, made of 35 national ringing centres; sister organisations exist in other parts of the world (like Africa, Australia, U.S. and Canada), sharing the same aims and problems. This RTD is mainly targeted to ornithologists involved with the co-ordination of bird ringing stations and national centres world-wide. Common aspects of the organisation of ringing activities, as well as of the potential ringing has and will have in the future in addressing major scientific questions in Ornithology will be taken into account. The advisability of setting up a standing committee on bird ringing within the IOC will be discussed, and the project of creating a world-wide organisation of ringing schemes in order to further improve communication and exchange of experiences will also be addressed. This new organisation would be formally founded in 1999, when an international conference organised by EURING to celebrate the first 100 years of bird ringing will be held in Denmark.

  18. Vascular ring (image)

    MedlinePlus

    Vascular ring is a term used to describe a number of abnormal formations of the aorta, the large artery ... the pulmonary artery. The abnormal vessel(s) forms a ring, which encircles and may press down on the ...

  19. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings. PMID:16601188

  20. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings.

  1. Saturn's F-Ring

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 6.9 million km from Saturn on 8 November 1980. The brightness variations of this tightly-constrained ring shown here indicate that the ring is less uniform in makeup than the larger rings. JPL managed the Voyager Project for NASA's Office of Space Science

  2. Rings Around Uranus

    ERIC Educational Resources Information Center

    Maran, Stephen P.

    1977-01-01

    Events leading up to the discovery of the rings of Uranus are described. The methods used and the logic behind the methods are explained. Data collected to prove the existence of the rings are outlined and theories concerning the presence of planetary rings are presented. (AJ)

  3. Transport from the Recycler Ring to the Antiproton Source Beamlines

    SciTech Connect

    Xiao, M.; /Fermilab

    2012-05-14

    In the post-NOvA era, the protons are directly transported from the Booster ring to the Recycler ring rather than the Main Injector. For Mu2e and g-2 project, the Debuncher ring will be modified into a Delivery ring to deliver the protons to both Mu2e and g-2 experiments. Therefore, it requires the transport of protons from the Recycler Ring to the Delivery ring. A new transfer line from the Recycler ring to the P1 beamline will be constructed to transport proton beam from the Recycler Ring to existing Antiproton Source beamlines. This new beamline provides a way to deliver 8 GeV kinetic energy protons from the Booster to the Delivery ring, via the Recycler, using existing beam transport lines, and without the need for new civil construction. This paper presents the Conceptual Design of this new beamline.

  4. Thermal Studies of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Pilorz, S.; Altobelli, N.; Leyrat, C.; Spilker, L.

    2007-12-01

    The observed thermal emission from Saturn's rings has a locational and directional variation that ultimately results from the time dependent response of individual ring particles to the quasi-periodic radiation forcing they experience as they orbit Saturn. The observed thermal emission from any radial region of the rings is representative of a large ensemble of particles or structures which are subject to statistically similar conditions as they orbit. Near any particular radius, the thermal forcing and response are quasi-periodic around an orbit, varying secularly with Saturn's twenty-nine year seasonal cycle. This talk will discuss the coupled thermal and radiative transfer processes within the rings as determined by the interplay between individual particle properties and those of the ensemble (i.e., the ring structure), and the constraints that are placed on those by the most comprehensive thermal observations of the rings to date, taken with the Cassini Infrared Spectrometer (CIRS). Over one hundred thousand thermal-infrared spectra of the rings, between 10 and 500 cm-1, have been taken with the CIRS Focal Plane 1 (FP1) detector since Cassini orbit insertion in July, 2004. They resemble scaled Planck functions with well resolved peaks indicative of temperatures between approximately 60 and 120 K. We investigate the properties of a mapping from a space of physical parameters describing ring particles and their distribution onto predicted time-dependent spectral thermal emission. Ring emission is modeled using a radiative transfer code augmented with ray tracing calculations; a thermal model is embedded within the calculation to model the particles as a thermal source, and statistical averaging is incorporated. The model is specified by a vector of parameters describing a vertically varying particle size distribution, spin distribution, thermal inertia, albedo and optical depth, and when driven by radiation calculated from ephemeris parameters it produces a self

  5. Unveiling the physics of the Thomson jumping ring

    NASA Astrophysics Data System (ADS)

    Ladera, Celso L.; Donoso, Guillermo

    2015-04-01

    We present a new theoretical model and validating experiments that unveil the rich physics behind the flight of the conductive ring in the Thomson experiment—physics that is hard to see because of the rapid motion. The electrodynamics of the flying ring exhibits interesting features, e.g., varying mutual inductance between the ring and the electromagnet. The dependences of the ring electrodynamics upon time and position as the ring travels upward are conveniently separated and determined to obtain a comprehensive view of the ring motion. We introduce a low-cost jumping ring setup that incorporates pickup coils connected in opposition, allowing us to scrutinize the ring electrodynamics and confirm our theoretical model with good accuracy. This work is within the reach of senior students of science or engineering, and it can be implemented either as a teaching laboratory experiment or as an open-ended project.

  6. Saturn's largest ring.

    PubMed

    Verbiscer, Anne J; Skrutskie, Michael F; Hamilton, Douglas P

    2009-10-22

    Most planetary rings in the Solar System lie within a few radii of their host body, because at these distances gravitational accelerations inhibit satellite formation. The best known exceptions are Jupiter's gossamer rings and Saturn's E ring, broad sheets of dust that extend outward until they fade from view at five to ten planetary radii. Source satellites continuously supply the dust, which is subsequently lost in collisions or by radial transport. Here we report that Saturn has an enormous ring associated with its outer moon Phoebe, extending from at least 128R(S) to 207R(S) (Saturn's radius R(S) is 60,330 km). The ring's vertical thickness of 40R(S) matches the range of vertical motion of Phoebe along its orbit. Dynamical considerations argue that these ring particles span the Saturnian system from the main rings to the edges of interplanetary space. The ring's normal optical depth of approximately 2 x 10(-8) is comparable to that of Jupiter's faintest gossamer ring, although its particle number density is several hundred times smaller. Repeated impacts on Phoebe, from both interplanetary and circumplanetary particle populations, probably keep the ring populated with material. Ring particles smaller than centimetres in size slowly migrate inward and many of them ultimately strike the dark leading face of Iapetus.

  7. Men's Understanding of and Experiences During the Postcircumcision Abstinence Period: Results From a Field Study of ShangRing Circumcision During Routine Clinical Services in Kenya and Zambia

    PubMed Central

    Li, Philip S.; Zulu, Robert; Awori, Quentin D.; Agot, Kawango; Combes, Stephanie; Simba, Raymond O.; Lee, Richard K.; Hart, Catherine; Lai, Jaim Jou; Zyambo, Zude; Goldstein, Marc; Feldblum, Paul J.; Sokal, David C.

    2016-01-01

    Background: Men's understanding of counseling messages after voluntary medical male circumcision (VMMC) plays an important role in whether they follow them. Data on triggers for early resumption of sex may be useful as scale-up of VMMC for HIV prevention continues in sub-Saharan Africa. Methods: Data on understanding of post-VMMC abstinence recommendations, resumption of sex, condom use, and triggers for resuming sex were collected from participants during a follow-up interview 35–42 days after ShangRing circumcision in Kenya and Zambia. Results: Of 1149 men who had ShangRing circumcision, 1096 (95.4%) completed follow-up. Nearly all (99.2%) reported being counseled to abstain from sex post-VMMC; among those, most (92.2%) recalled the recommended abstinence period was 6 weeks. Most men (94.1%) reported that the counselor gave reasons for post-VMMC abstinence and recalled appropriate reasons. Few (13.4%) men reported resuming sex at 35–42 days' follow-up. Among those, 54.8% reported never using a condom post-VMMC. Younger participants (odds ratio 0.3, 95% confidence interval: 0.2 to 0.5, P < 0.0001) and those reporting at least some condom use at baseline (odds ratio 0.5, 95% confidence interval: 0.3 to 0.7, P = 0.0003) were less likely to report resuming sex. Among men who reported some condom use, most (71.5%) said condoms were much easier or easier to use after circumcision. Men reported various reasons for early resumption of sex, primarily strong sexual desire (76.4%). Conclusions: Most men reported awareness of and adherence to the counseling recommendations for post-VMMC abstinence. A minority reported early resumption of sex, and, among those, condom use was low. Results could be used to improve post-VMMC counseling. PMID:27331585

  8. Dust and Planetary Rings

    NASA Astrophysics Data System (ADS)

    Siddiqui, Muddassir

    ABSTRACT Space is not empty it has comic radiations (CMBR), dust etc. Cosmic dust is that type of dust which is composed of particles in space which vary from few molecules to 0.1micro metres in size. This type of dust is made up of heavier atoms born in the heart of stars and supernova. Mainly it contains dust grains and when these dust grains starts compacting then it turns to dense clouds, planetary ring dust and circumstellar dust. Dust grains are mainly silicate particles. Dust plays a major role in our solar system, for example in zodiacal light, Saturn's B ring spokes, planetary rings at Jovian planets and comets. Observations and measurements of cosmic dust in different regions of universe provide an important insight into the Universe's recycling processes. Astronomers consider dust in its most recycled state. Cosmic dust have radiative properties by which they can be detected. Cosmic dusts are classified as intergalactic dusts, interstellar dusts and planetary rings. A planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in flat disc shape. All of the Jovian planets in our solar system have rings. But the most notable one is the Saturn's ring which is the brightest one. In March 2008 a report suggested that the Saturn's moon Rhea may have its own tenuous ring system. The ring swirling around Saturn consists of chunks of ice and dust. Most rings were thought to be unstable and to dissipate over course of tens or hundreds of millions of years but it now appears that Saturn's rings might be older than that. The dust particles in the ring collide with each other and are subjected to forces other than gravity of its own planet. Such collisions and extra forces tend to spread out the rings. Pluto is not known to have any ring system but some Astronomers believe that New Horizons probe might find a ring system when it visits in 2015.It is also predicted that Phobos, a moon of Mars will break up and form into a planetary ring

  9. Powder-lubricated piston ring development

    NASA Astrophysics Data System (ADS)

    Heshmat, H.

    1991-06-01

    The overall objective of this program was to demonstrate the feasibility of a new particulate lubrication concept for reducing piston ring/cylinder liner wear in coal-water slurry-fueled diesels by replacing the present oil-lubricated system with powder lubrication that would utilize coal ash, either alone or in combination with another powder. The feasibility of this particular lubrication concept for reducing ring/liner wear was demonstrated in a series of experiments utilizing redesigned and properly selected components. Wear performance for suitable ring/liner materials lubricated with a powder that incorporates the abrasive ash particles was evaluated in terms of load capacity, friction, and rate of wear for the best combination of ring design, ring and liner materials, and powder constituents. In addition, the use of a powder-lubricated system in the upper portion of the cylinder isolated the particulates from the lower portions of the engine, thus further reducing engine wear.

  10. Powder-lubricated piston ring development

    SciTech Connect

    Heshmat, H.

    1991-06-01

    The overall objective of this program was to demonstrate the feasibility of a new particulate lubrication concept for reducing piston ring/cylinder liner wear in coal-water slurry-fueled diesels by replacing the present oil-lubricated system with powder lubrication that would utilize coal ash, either alone or in combination with another powder. The feasibility of this particular lubrication concept for reducing ring/liner wear was demonstrated in a series of experiments utilizing redesigned and properly selected components. Wear performance for suitable ring/liner materials lubricated with a powder that incorporates the abrasive ash particles was evaluated in terms of load capacity, friction, and rate of wear for the best combination of ring design, ring and liner materials, and powder constituents. In addition, the use of a powder-lubricated system in the upper portion of the cylinder isolated the particulates from the lower portions of the engine, thus further reducing engine wear. (VC)

  11. On multiple Einstein rings

    NASA Astrophysics Data System (ADS)

    Werner, M. C.; An, J.; Evans, N. W.

    2008-12-01

    A number of recent surveys for gravitational lenses have found examples of double Einstein rings. Here, we analytically investigate the occurrence of multiple Einstein rings. We prove, under very general assumptions, that at the most one Einstein ring can arise from a mass distribution in a single plane lensing a single background source. Two or more Einstein rings can therefore only occur in multiplane lensing. Surprisingly, we show that it is possible for a single source to produce more than one Einstein ring. If two point masses, or two isothermal spheres, in different planes are aligned with observer and source on the optical axis, we show that there are up to three Einstein rings. We also discuss the image morphologies for these two models if axisymmetry is broken, and give the first instances of magnification invariants in the case of two-lens planes.

  12. Radioactive gold ring dermatitis

    SciTech Connect

    Miller, R.A.; Aldrich, J.E. )

    1990-08-01

    A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy.

  13. Temperatures of Saturn's rings.

    NASA Technical Reports Server (NTRS)

    Murphy, R. E.

    1973-01-01

    The 20-micron brightness temperatures of the rings were determined using the 224-cm telescope of the Mauna Kea Observatory, and the standard University of Hawaii radiometer with a 17- to 25-micron filter. The observations were made on the nights of Aug. 20 and 21, and Sept. 26 and 27, 1972. The brightness temperatures of the A, B, and C rings are, respectively, 89 plus or minus 3 K, 94 plus or minus 2 K, and 89 plus or minus 4 K. A possible explanation of the relatively high temperature of the C ring is that Saturn has radiation belts and the inner ring is heated by particle bombardment.

  14. Ring Around a Galaxy

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Space Telescope Science Institute astronomers are giving the public chances to decide where to aim NASA's Hubble Space Telescope. Guided by 8,000 Internet voters, Hubble has already been used to take a close-up, multi-color picture of the most popular object from a list of candidates, the extraordinary 'polar-ring' galaxy NGC 4650A. Located about 130 million light-years away, NGC 4650A is one of only 100 known polar-ring galaxies. Their unusual disk-ring structure is not yet understood fully. One possibility is that polar rings are the remnants of colossal collisions between two galaxies sometime in the distant past, probably at least 1 billion years ago. What is left of one galaxy has become the rotating inner disk of old red stars in the center. Meanwhile, another smaller galaxy which ventured too close was probably severely damaged or destroyed. The bright bluish clumps, which are especially prominent in the outer parts of the ring, are regions containing luminous young stars, examples of stellar rebirth from the remnants of an ancient galactic disaster. The polar ring appears to be highly distorted. No regular spiral pattern stands out in the main part of the ring, and the presence of young stars below the main ring on one side and above on the other shows that the ring is warped and does not lie in one plane. Determining the typical ages of the stars in the polar ring is an initial goal of our Polar Ring Science Team that can provide a clue to the evolution of this unusual galaxy. The HST exposures were acquired by the Hubble Heritage Team, consisting of Keith Noll, Howard Bond, Carol Christian, Jayanne English, Lisa Frattare, Forrest Hamilton, Anne Kinney and Zolt Levay, and guest collaborators Jay Gallagher (University of Wisconsin-Madison), Lynn Matthews (National Radio Astronomy Observatory-Charlottesville), and Linda Sparke (University of Wisconsin-Madison).

  15. Smoke Ring Physics

    ERIC Educational Resources Information Center

    Huggins, Elisha

    2011-01-01

    The behavior of smoke rings, tornados, and quantized vortex rings in superfluid helium has many features in common. These features can be described by the same mathematics we use when introducing Ampere's law in an introductory physics course. We discuss these common features. (Contains 7 figures.)

  16. Lower esophageal ring (Schatzki)

    MedlinePlus

    ... narrowed area to stretch the ring. Sometimes, a balloon is placed in the area and inflated, to help widen the ring. Outlook (Prognosis) Swallowing problems may return. You may need repeat treatment. When to Contact a Medical Professional Call your health care provider if you ...

  17. EBT ring physics

    SciTech Connect

    Uckan, N.A.

    1980-04-01

    This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers. (MOW)

  18. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki (Inventor); Deardon, Joe D. (Inventor)

    1997-01-01

    A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.

  19. Smoke Ring Physics

    NASA Astrophysics Data System (ADS)

    Huggins, Elisha

    2011-11-01

    The behavior of smoke rings, tornados, and quantized vortex rings in superfluid helium has many features in common. These features can be described by the same mathematics we use when introducing Ampère's law in an introductory physics course. We discuss these common features.

  20. Jupiter's Gossamer Rings Explained.

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.

    2003-05-01

    Over the past several years, Galileo measurements and groundbased imaging have drastically improved our knowledge of Jupiter's faint ring system. We now recognize that the ring consists of four components: a main ring 7000km wide, whose inner edge blossoms into a vertically-extended halo, and a pair of more tenuous Gossamer rings, one associated with each of the small moons Thebe and Amalthea. When viewed edge on, the Gossamer rings appear as diaphanous disks whose thicknesses agree with the vertical excursions of the inclined satellites from the equatorial plane. In addition, the brightness of each Gossamer ring drops off sharply outside the satellite orbits. These correlations allowed Burns etal (1999, Science, 284, 1146) to argue convincingly that the satellites act as sources of the dusty ring material. In addition, since most material is seen inside the orbits of the source satellites, an inwardly-acting dissipative force such as Poynting-Robertson drag is implicated. The most serious problem with this simple and elegant picture is that it is unable to explain the existence of a faint swath of material that extends half a jovian radius outward from Thebe. A key constraint is that this material has the same thickness as the rest of the Thebe ring. In this work, we identify the mechanism responsible for the outward extension: it is a shadow resonance, first investigated by Horanyi and Burns (1991, JGR, 96, 19283). When a dust grain enters Jupiter's shadow, photoelectric processes shut down and the grain's electric charge becomes more negative. The electromagnetic forces associated with the varying charge cause periodic oscillations in the orbital eccentricity and semimajor axis as the orbital pericenter precesses. This results in a ring which spreads both inward and outward of its source satellite while preserving its vertical thickness - just as is observed for the Thebe ring. Predictions of the model are: i) gaps of micron-sized material interior to Thebe and

  1. Jupiter's Rings: Sharpest View

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The New Horizons spacecraft took the best images of Jupiter's charcoal-black rings as it approached and then looked back at Jupiter. The top image was taken on approach, showing three well-defined lanes of gravel- to boulder-sized material composing the bulk of the rings, as well as lesser amounts of material between the rings. New Horizons snapped the lower image after it had passed Jupiter on February 28, 2007, and looked back in a direction toward the sun. The image is sharply focused, though it appears fuzzy due to the cloud of dust-sized particles enveloping the rings. The dust is brightly illuminated in the same way the dust on a dirty windshield lights up when you drive toward a 'low' sun. The narrow rings are confined in their orbits by small 'shepherding' moons.

  2. STEEL TRUSS TENSION RING SUPPORTING DOME ROOF. TENSION RING COVERED ...

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

    STEEL TRUSS TENSION RING SUPPORTING DOME ROOF. TENSION RING COVERED BY ARCHITECTURAL FINISH. TENSION RING ROLLER SUPPORT AT COLUMN OBSCURED BY COLUMN COVERINGS. - Houston Astrodome, 8400 Kirby Drive, Houston, Harris County, TX

  3. News from the CSR storage ring

    NASA Astrophysics Data System (ADS)

    Ma, X.; Xu, H. S.; Xia, J. W.; Yang, X. D.; Meng, L. J.; Wang, M.; Tu, X. L.; Liu, H. P.; Hu, Z. G.; Zhu, X. L.; Mao, R. S.; Zhang, D. C.; Mao, L. J.; Li, J.; Li, G. H.; Liu, Y.; Yang, J. C.; Yuan, Y. J.; Cai, X. H.; Zheng, J. H.; Yang, X. T.; Xiao, G. Q.; Zhan, W. L.

    2009-11-01

    Testing runs of experiments were performed at the Cooler Storage Ring in Lanzhou. The recombination of bare argon ions and electron was observed at the electron. The masses of radioactive nuclei produced by projectile fragmentation were measured in isochronous mode. An overview of the most recent experiments will be presented.

  4. The Enceladus Ring

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] The Enceladus Ring (labeled)

    This excellent view of the faint E ring -- a ring feature now known to be created by Enceladus -- also shows two of Saturn's small moons that orbit within the ring, among a field of stars in the background.

    The E ring extends from three to eight Saturn radii -- about 180,000 kilometers (118,000 miles) to 482,000 kilometers (300,000 miles). Its full extent is not visible in this view.

    Calypso (22 kilometers, or 14 miles across) and Helene (32 kilometers, or 20 miles across) orbit within the E ring's expanse. Helene skirts the outer parts of the E ring, but here it is projected in front of a region deeper within the ring.

    Calypso and Helene are trojan satellites, or moons that orbit 60 degrees in front or behind a larger moon. Calypso is a Tethys trojan and Helene is a trojan of Dione.

    An interesting feature of note in this image is the double-banded appearance of the E-ring, which is created because the ring is somewhat fainter in the ringplane than it is 500-1,000 kilometers (300-600 miles) above and below the ringplane. This appearance implies that the particles in this part of the ring have nonzero inclinations (a similar affect is seen in Jupiter's gossamer ring). An object with a nonzero inclination does not orbit exactly at Saturn's ringplane. Instead, its orbit takes it above and below the ringplane. Scientists are not entirely sure why the particles should have such inclinations, but they are fairly certain that the reason involves Enceladus.

    One possible explanation is that all the E ring particles come from the plume of icy material that is shooting due south out of the moon's pole. This means all of the particles are created with a certain velocity out of the ringplane, and then they orbit above and below that plane.

    Another possible explanation is that Enceladus produces particles with a range of speeds, but the moon gravitationally

  5. Piston ring conformability in a distorted bore

    SciTech Connect

    Tomanik, E.

    1996-09-01

    Some different equations to calculate the maximum deformation that a given ring can conform to, are found in the bibliography. These equations do not consider the ring end gap and ovality, gas pressure acting on it, nor the actual bore shape, but only the maximum amplitude for a given term (from a fourier Series that describes the bore shape). A more exact prediction can be done with Finite Element tools or specific codes for piston ring simulation; those approaches are not usually carried out, except in special cases or in more fundamental studies. Experimental measurements were carried out to verify the simple conformability criteria. Deformed shapes were produced in a static jig and areas of non contact, between ring and the deformed bore shapes, were measured. Based on these measurements, a semi-empirical equation is proposed to calculate the limit of piston ring conformability. The proposed equation is simple enough to be calculated in the initial engine design phases (where the required inputs to more detailed methods are not available) or on a day-by-day basis. If bore deformation surpasses the ring conformability, the percentage of ring periphery contacting the bore can be estimated, in a first approximation, by the linear regression empirically found in the experiments.

  6. Earth: A Ringed Planet?

    NASA Astrophysics Data System (ADS)

    Hancock, L. O.; Povenmire, H.

    2010-12-01

    Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

  7. Hot piston ring tests

    NASA Astrophysics Data System (ADS)

    Allen, David J.; Tomazic, William A.

    1987-12-01

    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.

  8. Dynamics of narrow rings

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.

    1984-01-01

    The ring models described here were developed to account for the dynamical problems posed by the narrow rings of Uranus. Some of these rings are now known to be eccentric, inclined, nonuniform in width, optically thick, and narrow, with very sharp edges. The eccentric rings have common pericenters and large, positive eccentricity gradients. The theory of shepherding satellites successfully accounts for most of these features and can also account for some features of the narrow Saturnian rings, in particular, waves, kinks, and periodic variations in brightness. Outstanding problems include the putative relation between eccentricity and inclination displayed by eight of the nine Uranian rings, and the magnitudes of the tidal torques acting on the shepherding satellites. The horseshoe-orbit model, although viable, probably has more application to the narrow rings from which the Saturnian coorbital satellites formed. The angular momentum flow rate due to particle collisions is a minimum at the Lagrangian equilibrium points L(4) and L(5), and one can expect accretion to be rapid at these points.

  9. 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.

  10. Dynamics of the Uranian Rings

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.

    1984-01-01

    Some of the problems of the shepherding satellite model of Goldreich ant tremaine are discussed. The following topics are studied: (1) optical depths of the all the observed narrow rings; (2) satellite and ring separation timescales; (3) ring edge sharpness; (4) shock formation in narrow rings; (5) the existence of small satellites near the Uranian rings; and (6) the apse and node alignments of the eccentric and inclined rings.

  11. Theodolite Ring Lights

    NASA Technical Reports Server (NTRS)

    Clark, David

    2006-01-01

    Theodolite ring lights have been invented to ease a difficulty encountered in the well-established optical-metrology practice of using highly reflective spherical tooling balls as position references. A theodolite ring light produces a more easily visible reflection and eliminates the need for an autocollimating device. A theodolite ring light is a very bright light source that is well centered on the optical axis of the instrument. It can be fabricated, easily and inexpensively, for use on a theodolite or telescope of any diameter.

  12. Alternative parallel ring protocols

    NASA Technical Reports Server (NTRS)

    Mukkamala, R.; Foudriat, E. C.; Maly, Kurt J.; Kale, V.

    1990-01-01

    Communication protocols are know to influence the utilization and performance of communication network. The effect of two token ring protocols on a gigabit network with multiple ring structure is investigated. In the first protocol, a mode sends at most one message on receiving a token. In the second protocol, a mode sends all the waiting messages when a token is received. The behavior of these protocols is shown to be highly dependent on the number of rings as well as the load in the network.

  13. The Brookhaven muon storage ring magnet

    NASA Astrophysics Data System (ADS)

    Danby, G. T.; Addessi, L.; Armoza, Z.; Benante, J.; Brown, H. N.; Bunce, G.; Cottingham, J. C.; Cullen, J.; Geller, J.; Hseuh, H.; Jackson, J. W.; Jia, L.; Kochis, S.; Koniczny, D.; Larsen, R.; Lee, Y. Y.; Mapes, M.; Meier, R. E.; Meng, W.; Morse, W. M.; O'Toole, M.; Pai, C.; Polk, I.; Prigl, R.; Semertzidis, Y. K.; Shutt, R.; Snydstrup, L.; Soukas, A.; Tallerico, T.; Toldo, F.; Von Lintig, D.; Woodle, K.; Carey, R. M.; Earle, W.; Hazen, E. S.; Krienen, F.; Miller, J. P.; Ouyang, J.; Roberts, B. L.; Sulak, L. R.; Worstell, W. A.; Orlov, Y.; Winn, D.; Grossmann, A.; Jungmann, K.; zu Putlitz, G.; von Walter, P.; Debevec, P. T.; Deninger, W. J.; Hertzog, D. W.; Sedykh, S.; Urner, D.; Green, M. A.; Haeberlen, U.; Cushman, P.; Giron, S.; Kindem, J.; Miller, D.; Timmermans, C.; Zimmerman, D.; Druzhinin, V. P.; Fedotovich, G. V.; Grigorev, D. N.; Khazin, B. I.; Ryskulov, N. M.; Serednyakov, S.; Shatunov, Yu. M.; Solodov, E.; Endo, K.; Hirabayashi, H.; Mizumachi, Y.; Yamamoto, A.; Dhawan, S. K.; Disco, A.; Farley, F. J. M.; Fei, X.; Grosse-Perdekamp, M.; Hughes, V. W.; Kawall, D.; Redin, S. I.

    2001-01-01

    The muon g-2 experiment at Brookhaven National Laboratory has the goal of determining the muon anomalous g-value a μ (=(g-2)/2) to the very high precision of 0.35 parts per million and thus requires a storage ring magnet with great stability and homogeniety. A superferric storage ring with a radius of 7.11 m and a magnetic field of 1.45 T has been constructed in which the field quality is largely determined by the iron, and the excitation is provided by superconducting coils operating at a current of 5200 A. The storage ring has been constructed with maximum attention to azimuthal symmetry and to tight mechanical tolerances and with many features to allow obtaining a homogenous magnetic field. The fabrication of the storage ring, its cryogenics and quench protection systems, and its initial testing and operation are described.

  14. Vortex ring impingement and particle suspension

    NASA Astrophysics Data System (ADS)

    Staymates, Matthew

    2005-11-01

    Previous research has shown that the impact of a vortex ring with a solid surface can dislodge particles attached to that surface and suspend them in the surrounding fluid. A possible use for this phenomenon arises in the detection of trace explosives on clothing and belongings: Once liberated from the surface, suspended particles can be collected and interrogated. The current technology successfully uses round turbulent jets for this purpose, but also generates a large concomitant airflow due to entrainment. Here we present the results of initial experiments to construct vortex-ring generators producing a similar particle release from surfaces with much less entrainment than jets. A discussion of vortex-ring-generator design issues and semi-quantitative flow visualization results will be presented. Both normal and oblique vortex-ring impacts are considered.

  15. Dedicated storage rings for nuclear physics

    SciTech Connect

    Jackson, H.E.

    1984-01-01

    The use of internal targets in circulating beams of electron storage and stretcher rings has been widely discussed recently as a method of achieving high luminosity under conditions of low background, and good energy resolution, with minimal demands for beam from an injecting accelerator. In the two critical areas of the technology, ring design and target development, research is very active, and the prospects for major advances are very bright. Reasonable extrapolations of the current state of the art suggest for many problems in nuclear physics, particularly polarization physics of the nucleon and few body nuclei, internal target measurement may be the optimum experimental technique. This paper, discusses the comparative merit of internal target rings and external beam experiments, reviews briefly current research efforts in the critical areas of the technology, and establishes one goal for the discussions at the workshop. It appears that storage rings dedicated to internal target physics may offer a powerful option for future advances in nuclear physics.

  16. Reflex ring laser amplifier system

    SciTech Connect

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  17. Highlights in planetary rings

    NASA Astrophysics Data System (ADS)

    Porco, Carolyn C.

    1995-07-01

    There is a rich phenomenology within the planetary rings surrounding the giant planets, most of it discovered by the Voyagers during their historic tours of t he outer solar system in the 1980s. In the last decade, there have been two detailed IUGG reviews of planetary rings. Cuzzi [1983] covered the time period from 1979-1983 which included the Pioneer 11 encounter with Saturn (1979), the Voyager 1 and 2 encounters with Jupiter (1979) and with Saturn (1980 and 1981). Nicholson and Dones [1991] reviewed the developments in the field between 1984 and 1991, a period of time which included the Voyager 2 Uranus (1986) and Neptune (1989) encounters. (References t o additional reviews of planetary rings and related fields can be found in Nicholson and Dones [1991].) Rather than being comprehensive in nature, this review will concentrate on only those areas of ring research in which particularly promising developments have occurred in the last half decade.

  18. Heating Saturn's Clumpy Rings

    NASA Astrophysics Data System (ADS)

    Turner, Neal J.; Morishima, Ryuji; Spilker, Linda J.

    2015-11-01

    We model Cassini CIRS data using a Monte Carlo radiative transfer -- thermal balance technique first developed for protostellar disks, with the goals of:1. Exploring whether the A- and B-ring temperatures' variation with viewing angle is consistent with the wake structures suggested by the observed azimuthal asymmetry in optical depth, by analytic arguments, and by numerical N-body modeling.2. Better constraining the shape, size, spacing and optical depths of substructure in the A-ring, using the unexpectedly high temperatures observed at equinox. If the wake features have high enough contrast, Saturn-shine may penetrate the gaps between the wakes and heat thering particles both top and bottom.3. Determining how much of the heating of the A- and B-rings' unlit sides is due to radiative transport and how much is due to particle motions, especially vertical motions. This will help in constraining the rings' surface densities and masses.

  19. Saturn's dynamic D ring

    USGS Publications Warehouse

    Hedman, M.M.; Burns, J.A.; Showalter, M.R.; Porco, C.C.; Nicholson, P.D.; Bosh, A.S.; Tiscareno, M.S.; Brown, R.H.; Buratti, B.J.; Baines, K.H.; Clark, R.

    2007-01-01

    The Cassini spacecraft has provided the first clear images of the D ring since the Voyager missions. These observations show that the structure of the D ring has undergone significant changes over the last 25 years. The brightest of the three ringlets seen in the Voyager images (named D72), has transformed from a narrow, <40-km wide ringlet to a much broader and more diffuse 250-km wide feature. In addition, its center of light has shifted inwards by over 200 km relative to other features in the D ring. Cassini also finds that the locations of other narrow features in the D ring and the structure of the diffuse material in the D ring differ from those measured by Voyager. Furthermore, Cassini has detected additional ringlets and structures in the D ring that were not observed by Voyager. These include a sheet of material just interior to the inner edge of the C ring that is only observable at phase angles below about 60??. New photometric and spectroscopic data from the ISS (Imaging Science Subsystem) and VIMS (Visual and Infrared Mapping Spectrometer) instruments onboard Cassini show the D ring contains a variety of different particle populations with typical particle sizes ranging from 1 to 100 microns. High-resolution images reveal fine-scale structures in the D ring that appear to be variable in time and/or longitude. Particularly interesting is a remarkably regular, periodic structure with a wavelength of ??? 30 ?? km extending between orbital radii of 73,200 and 74,000 km. A similar structure was previously observed in 1995 during the occultation of the star GSC5249-01240, at which time it had a wavelength of ??? 60 ?? km. We interpret this structure as a periodic vertical corrugation in the D ring produced by differential nodal regression of an initially inclined ring. We speculate that this structure may have formed in response to an impact with a comet or meteoroid in early 1984. ?? 2006 Elsevier Inc. All rights reserved.

  20. Observations of A Young Agulhas Ring, During Mare

    NASA Astrophysics Data System (ADS)

    van Veldhoven, A. K.; van Aken, H. M.; Veth, C.

    The MARE (Mixing of Agulhas Rings Experiment) project studies the effects of inter- ocean exchange between the Indian and Atlantic Ocean, via Agulhas rings, on the Atlantic meridional overturning circulation. This presentation is about the field pro- gramme of MARE which concentrates on the study of the decay and modification of a single Agulhas ring named Astrid, formed in January 2000. The ring was first iden- tified by an analysis of satellite altimetry data. During a detailed survey of this two months old ring in March 2000 it appeared that the ring had a significant barotropic component, additional to the baroclinic flow around its warm centre. The influence of the present topography, the Agulhas Ridge, on this ring may therefore be important. The observed fine-structure near its boundary suggested that exchange of water with its surroundings already had started. During this presentation some highlights of the results will be presented.

  1. Ultrasonic Newton's rings

    SciTech Connect

    Hsu, D.K. ); Dayal, V. )

    1992-03-09

    Interference fringes due to bondline thickness variation were observed in ultrasonic scans of the reflected echo amplitude from the bondline of adhesively joined aluminum skins. To demonstrate that full-field interference patterns are observable in point-by-point ultrasonic scans, an optical setup for Newton's rings was scanned ultrasonically in a water immersion tank. The ultrasonic scan showed distinct Newton's rings whose radii were in excellent agreement with the prediction.

  2. Nardo Ring, Italy

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Nardo Ring is a striking visual feature from space, and astronauts have photographed it several times. The Ring is a race car test track; it is 12.5 kilometers long and steeply banked to reduce the amount of active steering needed by drivers. The Nardo Ring lies in a remote area on the heel of Italy's 'boot,' 50 kilometers east of the naval port of Taranto. The Ring encompasses a number of active (green) and fallow (brown to dark brown) agricultural fields. In this zone of intensive agriculture, farmers gain access to their fields through the Ring via a series of underpasses. Winding features within the southern section of the Ring appear to be smaller, unused race tracks.

    The image covers an area of 18.8 x 16.4 km, was acquired on August 17. 2007, and is located at 49.3 degrees north latitude, 17.8 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  3. Nanofiber-segment ring resonator

    NASA Astrophysics Data System (ADS)

    Jones, D. E.; Hickman, G. T.; Franson, J. D.; Pittman, T. B.

    2016-08-01

    We describe a fiber ring resonator comprised of a relatively long loop of standard single-mode fiber with a short nanofiber segment. The evanescent mode of the nanofiber segment allows the cavity-enhanced field to interact with atoms in close proximity to the nanofiber surface. We report on an experiment using a warm atomic vapor and low-finesse cavity, and briefly discuss the potential for reaching the strong coupling regime of cavity QED by using trapped atoms and a high-finesse cavity of this kind.

  4. Stability of equilibrium of a superconducting ring that levitates in the field of a fixed ring with constant current

    NASA Astrophysics Data System (ADS)

    Bishaev, A. M.; Bush, A. A.; Gavrikov, M. B.; Kamentsev, K. E.; Kozintseva, M. V.; Savel'ev, V. V.; Sigov, A. S.

    2015-11-01

    In order to develop a plasma trap with levitating superconducting magnetic coils, it is necessary to search for their stable levitating states. An analytical expression for the potential energy of a single superconducting ring that captures a fixed magnetic flux in the field of a fixed ring with constant current versus the coordinate of the free ring on the axis of the system, deviation angle of its axis from the axis of the system, and radial displacement of its plane is derived for uniform gravity field in the thin ring approximation. The calculated stable levitation states of the superconducting ring in the field of the ring with constant current are proven in experiments. The generalization of such an approach to the levitation of several rings makes it possible to search for stable levitation states of several coils that form a magnetic system of a multipole trap.

  5. Propellers in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Sremcevic, M.; Stewart, G. R.; Albers, N.; Esposito, L. W.

    2014-04-01

    Theoretical studies and simulations have demonstrated the effects caused by objects embedded in planetary rings [5, 8]. Even if the objects are too small to be directly observed, each creates a much larger gravitational imprint on the surrounding ring material. These strongly depend on the mass of the object and range from "S" like propeller-shaped structures for about 100m-sized icy bodies to the opening of circumferential gaps as in the case of the embedded moons Pan and Daphnis and their corresponding Encke and Keeler Gaps. Since the beginning of the Cassini mission many of these smaller objects (~ 100m in size) have been identified in Saturn's A ring through their propeller signature in the images [10, 7, 9, 11]. Furthermore, recent Cassini observations indicate the possible existence of objects embedded even in Saturn's B and C ring [6, 2]. In this paper we present our new results about by now classical A ring propellers and more enigmatic B ring population. Due to the presence of self-gravity wakes the analysis of propeller brightness in ISS images always bears some ambiguity [7, 9] and consequently the exact morphology of propellers is not a settled issue. In 2008 we obtained a fortunate Cassini Ultraviolet Imaging Spectrograph (UVIS) occultation of the largest A ring propeller Bleriot. Utilizing Cassini ISS images we obtain Bleriot orbit and demonstrate that UVIS Persei Rev42 occultation did cut across Bleriot about 100km downstream from the center. The occultation itself shows a prominent partial gap and higher density outer flanking wakes, while their orientation is consistent with a downstream cut. While in the UVIS occultation the partial gap is more prominent than the flanking wakes, the features mostly seen in Bleriot images are actually flanking wakes. One of the most interesting aspects of the A ring propellers are their wanderings, or longitudinal deviations from a pure circular orbit [11]. We numerically investigated the possibility of simple moon

  6. Retaining-Ring Installation Tool

    NASA Technical Reports Server (NTRS)

    Christian, S.

    1983-01-01

    New tool eliminates damage to ring through improper tool use. Tool installs spiral-wound retaining rings quickly, reliably, and safely. Tool inserts rings in splined or irregularly shaped bores, bores at bottom of deep ring and slides it along bore until it nests in groove. Pistons are moved by variety of linkages.

  7. PREFACE: Special section on vortex rings Special section on vortex rings

    NASA Astrophysics Data System (ADS)

    Fukumoto, Yasuhide

    2009-10-01

    This special section of Fluid Dynamics Research includes five articles on vortex rings in both classical and quantum fluids. The leading scientists of the field describe the trends in and the state-of-the-art development of experiments, theories and numerical simulations of vortex rings. The year 2008 was the 150th anniversary of 'vortex motion' since Hermann von Helmholtz opened up this field. In 1858, Helmholtz published a paper in Crelle's Journal which put forward the concept of 'vorticity' and made the first analysis of vortex motion. Fluid mechanics before that was limited to irrotational motion. In the absence of vorticity, the motion of an incompressible homogeneous fluid is virtually equivalent to a rigid-body motion in the sense that the fluid motion is determined once the boundary configuration is specified. Helmholtz proved, among other things, that, without viscosity, a vortex line is frozen into the fluid. This Helmholtz's law immediately implies the preservation of knots and links of vortex lines and its implication is enormous. One of the major trends of fluid mechanics since the latter half of the 20th century is to clarify the topological meaning of Helmholtz's law and to exploit it to develop theoretical and numerical methods to find the solutions of the Euler equations and to develop experimental techniques to gain an insight into fluid motion. Vortex rings are prominent coherent structures in a variety of fluid motions from the microscopic scale, through human and mesoscale to astrophysical scales, and have attracted people's interest. The late professor Philip G Saffman (1981) emphasized the significance of studies on vortex rings. One particular motion exemplifies the whole range of problems of vortex motion and is also a commonly known phenomenon, namely the vortex ring or smoke ring. Vortex rings are easily produced by dropping drops of one liquid into another, or by puffing fluid out of a hole, or by exhaling smoke if one has the skill

  8. Thermodynamic black di-rings

    SciTech Connect

    Iguchi, Hideo; Mishima, Takashi

    2010-10-15

    Previously the five dimensional S{sup 1}-rotating black rings have been superposed in a concentric way by some solitonic methods, and regular systems of two S{sup 1}-rotating black rings were constructed by the authors and then Evslin and Krishnan (we called these solutions 'black di-rings'). In this place we show some characteristics of the solutions of five dimensional black di-rings, especially in thermodynamic equilibrium. After the summary of the di-ring expressions and their physical quantities, first we comment on the equivalence of the two different solution sets of the black di-rings. Then the existence of thermodynamic black di-rings is shown, in which both isothermality and isorotation between the inner black ring and the outer black ring are realized. We also give detailed analysis of peculiar properties of the thermodynamic black di-ring including discussion about a certain kind of thermodynamic stability (instability) of the system.

  9. Mapping Ring Particle Cooling across Saturn's Rings with Cassini CIRS

    NASA Astrophysics Data System (ADS)

    Brooks, Shawn M.; Spilker, L. J.; Edgington, S. G.; Pilorz, S. H.; Deau, E.

    2010-10-01

    Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and quick temperature responses are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent particles can be expected to have higher thermal inertias (Ferrari et al. 2005). Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communication, M. Segura). CIRS records far infrared radiation between 10 and 600 cm-1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn's rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The thermal budget of the rings is dominated by the solar radiation absorbed by its constituent particles. When ring particles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring particles cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

  10. Saturn's Other Ring Current

    NASA Astrophysics Data System (ADS)

    Crary, F. J.

    2014-04-01

    Saturn's main rings orbit the planet within an atmosphere and ionosphere of water, oxygen and hydrogen, produced by meteoritic impacts on and ultraviolet photodesorbtion of the ring particles [Johnson et al., 2006; Luhmann et al., 2006; Tseng et al., 2010]. The neutral atmosphere itself has only been tentatively detected through ultraviolet fluorescents of OH [Hall et al., 1996] while the ionosphere was observed in situ by the Cassini spacecraft shortly after orbital insertion [Coates et al.,2005; Tokar et al. 2005, Waite et al. 2005]. Although the plasma flow velocity of this ionosphere is not well-constrained, but the close association with the rings suggests that its speed would be couppled to the keplarian velocity of the rings themselves. As a result, the motion of the plasma through Saturn's magnetic field would produce an induced voltage, oriented away from the planet outside synchronous orbit and towards the planet inside synchronous orbit. Such a potential could result in currents flowing across the ring plane and closeing along magnetic field lines and through Saturn's ionosphere at latitudes between 36o and 48o. Cassini observations of whistler-mode plasma wave emissions [Xin et al.,2006] centered on synchronous orbit (1.76 Rs, mapping to 41o latitude) have been interpreted as a product of field-aligned electron beams associated with such a current. This presentation will investigate the magnitude of these currents and the resulting Joule heating of the ionosphere. An important constraint is that no auroral ultraviolet emissions have been observed at the relevant latitudes. In contrast, Joule heating could affect infrared emissions from H3+. Variations in H3+ emission associated with Saturn's rings have been reported by O'Donoghue et al., 2013, and interpreted as a result of ring "rain", i.e. precipitating water group species from the rings which alter ionosphereic chemistry and H3+ densities. As noted by O'Donoghue et al., this interpretation may be

  11. Piston Ring Pressure Distribution

    NASA Technical Reports Server (NTRS)

    Kuhn, M.

    1943-01-01

    The discovery and introduction of the internal combustion engine has resulted in a very rapid development in machines utilizing the action of a piston. Design has been limited by the internal components of the engine, which has been subjected to ever increasing thermal and mechanical stresses, Of these internal engine components, the piston and piston rings are of particular importance and the momentary position of engine development is not seldom dependent upon the development of both of the components, The piston ring is a well-known component and has been used in its present shape in the steam engine of the last century, Corresponding to its importance, the piston ring has been a rich field for creative activity and it is noteworthy that in spite of this the ring has maintained its shape through the many years. From the many and complicated designs which have been suggested as a packing between piston and cylinder wall hardly one suggestion has remained which does not resemble the original design of cast iron rectangular ring.

  12. Stacked Corrugated Horn Rings

    NASA Technical Reports Server (NTRS)

    Sosnowski, John B.

    2010-01-01

    This Brief describes a method of machining and assembly when the depth of corrugations far exceeds the width and conventional machining is not practical. The horn is divided into easily machined, individual rings with shoulders to control the depth. In this specific instance, each of the corrugations is identical in profile, and only differs in diameter and outer profile. The horn is segmented into rings that are cut with an interference fit (zero clearance with all machining errors biased toward contact). The interference faces can be cut with a reverse taper to increase the holding strength of the joint. The taper is a compromise between the interference fit and the clearance of the two faces during assembly. Each internal ring is dipped in liquid nitrogen, then nested in the previous, larger ring. The ring is rotated in the nest until the temperature of the two parts equalizes and the pieces lock together. The resulting assay is stable, strong, and has an internal finish that cannot be achieved through other methods.

  13. Two F Ring Views

    NASA Technical Reports Server (NTRS)

    2005-01-01

    These views, taken two hours apart, demonstrate the dramatic variability in the structure of Saturn's intriguing F ring.

    In the image at the left, ringlets in the F ring and Encke Gap display distinctive kinks, and there is a bright patch of material on the F ring's inner edge. Saturn's moon Janus (181 kilometers, or 113 miles across) is shown here, partly illuminated by reflected light from the planet.

    At the right, Prometheus (102 kilometers, or 63 miles across) orbits ahead of the radial striations in the F ring, called 'drapes' by scientists. The drapes appear to be caused by successive passes of Prometheus as it reaches the greatest distance (apoapse) in its orbit of Saturn. Also in this image, the outermost ringlet visible in the Encke Gap displays distinctive bright patches.

    These views were obtained from about three degrees below the ring plane.

    The images were taken in visible light with the Cassini spacecraft narrow-angle camera on June 29, 2005, when Cassini was about 1.5 million kilometers (900,000 miles) from Saturn. The image scale is about 9 kilometers (6 miles) per pixel.

  14. Rings in the solar system

    SciTech Connect

    Pollack, J.B.; Cuzzi, J.N.

    1981-11-01

    Saturn, Jupiter, and Uranus have rings with different structure and composition. The rings consist of tiny masses in independent orbits. Photographs and data obtained by the Voyager project have aided in the understanding of Saturn's rings. Spokes have been found in B ring and boards, knots, and twist in F ring. Particles on the order of a micrometer in size are believed to occur in F, B, and A rings. The dominant component is water ice. The rings of Uranus are narrow and separated by broad empty regions. The technique used to study them has been stellar occulation. Nothing is known of particle size. The dominant component is believed to be silicates rich in compounds that absorb sunlight. Jupiter's rings consist of 3 main parts: a bright ring, a diffuse disk, and a halo. Use of Pioneer 10 data and other techniques have indicated particle sizes on the order of several micrometers and some at least a centimeter in diameter. The architecture of the ring system results from the interplay of a number of forces. These include gravitational forces due to moons outside the rings and moonlets embedded in them, electromagnetic forces due to the planet's rotating magnetic field, and even the gentle forces exerted by the dilute gaseous medium in which the rings rotate. Each of these forces is discussed. Several alternative explanations of how the rings arose are considered. The primary difference in these hypotheses is the account of the relationship between the ring particles of today and the primordial ring material. (SC)

  15. Physics of planetary rings

    NASA Astrophysics Data System (ADS)

    Gorkavyi, N.

    2007-08-01

    It is difficult to enumerate all the surprises presented by the planetary rings. The Saturnian rings are stratified into thousands of ringlets and the Uranian rings are compressed into narrow streams, which for some reason or other differ from circular orbits like the wheel of an old bicycle. The edge of the rings is jagged and the rings themselves are pegged down under the gravitational pressure of the satellites, bending like a ship's wake. There are spiral waves, elliptical rings, strange interlacing of narrow ringlets, and to cap it all one has observed in the Neptunian ring system three dense, bright arcs - like bunches of sausages on a transparent string. For celestial mechanics this is a spectacle as unnatural as a bear's tooth in the necklace of the English queen. In the dynamics of planetary rings the physics of collective interaction was supplemented by taking collisions between particles into account. One was led to study a kinetic equation with a rather complex collision integral - because the collisions are inelastic - which later on made it possible, both by using the Chapman-Enskog method and by using the solution of the kinetic equation for a plasma in a magnetic field, to reduce it to a closed set of (hydrodynamical) moment equations [1]. The hydrodynamical instabilities lead to the growth of short-wavelength waves and large-scale structures of the Saturnian rings [1]. We have shown that the formation of the existing dense Uranian rings is connected with the capture of positively drifting ring particles in inner Lindblad resonances which arrest this drift [1]. After the formation of dense rings at the positions of satellite resonances the collective interaction between resonant particles is amplified and the rings can leave the resonance and drift away from the planet and the parent resonance. We can expect in the C ring an appreciable positive ballistic particle drift caused by the erosion of the B ring by micrometeorites. It is therefore natural

  16. Double Ring Craters

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A faint double ring crater is seen at upper right in this picture of Mercury (FDS 166601) taken one hour and 40 minutes before Mariner 10's second rendezvous with the planet September 21. Located 35 degrees S. Lat. The outer ring is 170 kilometers (10 miles) across. Double ring craters are common features on Mercury. This particular feature and the bright rayed crater to its left were seen from a different viewing angle in pictures taken by Mariner 10 during its first Mercury flyby last March 29.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    Image Credit: NASA/JPL/Northwestern University

  17. Deployable Fresnel Rings

    NASA Technical Reports Server (NTRS)

    Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.; Lin, Gregory Y.

    2014-01-01

    Deployable Fresnel rings (DFRs) significantly enhance the realizable gain of an antenna. This innovation is intended to be used in combination with another antenna element, as the DFR itself acts as a focusing or microwave lens element for a primary antenna. This method is completely passive, and is also completely wireless in that it requires neither a cable, nor a connector from the antenna port of the primary antenna to the DFR. The technology improves upon the previous NASA technology called a Tri-Sector Deployable Array Antenna in at least three critical aspects. In contrast to the previous technology, this innovation requires no connector, cable, or other physical interface to the primary communication radio or sensor device. The achievable improvement in terms of antenna gain is significantly higher than has been achieved with the previous technology. Also, where previous embodiments of the Tri-Sector antenna have been constructed with combinations of conventional (e.g., printed circuit board) and conductive fabric materials, this innovation is realized using only conductive and non-conductive fabric (i.e., "e-textile") materials, with the possible exception of a spring-like deployment ring. Conceptually, a DFR operates by canceling the out-of-phase radiation at a plane by insertion of a conducting ring or rings of a specific size and distance from the source antenna, defined by Fresnel zones. Design of DFRs follow similar procedures to those outlined for conventional Fresnel zone rings. Gain enhancement using a single ring is verified experimentally and through computational simulation. The experimental test setup involves a microstrip patch antenna that is directly behind a single-ring DFR and is radiating towards a second microstrip patch antenna. The first patch antenna and DFR are shown. At 2.42 GHz, the DFR improves the transmit antenna gain by 8.6 dB, as shown in Figure 2, relative to the wireless link without the DFR. A figure illustrates the

  18. Oligomeric ferrocene rings

    NASA Astrophysics Data System (ADS)

    Inkpen, Michael S.; Scheerer, Stefan; Linseis, Michael; White, Andrew J. P.; Winter, Rainer F.; Albrecht, Tim; Long, Nicholas J.

    2016-09-01

    Cyclic oligomers comprising strongly interacting redox-active monomer units represent an unknown, yet highly desirable class of nanoscale materials. Here we describe the synthesis and properties of the first family of molecules belonging to this compound category—differently sized rings comprising only 1,1‧-disubstituted ferrocene units (cyclo[n], n = 5-7, 9). Due to the close proximity and connectivity of centres (covalent Cp-Cp linkages; Cp = cyclopentadienyl) solution voltammograms exhibit well-resolved, separated 1e- waves. Theoretical interrogations into correlations based on ring size and charge state are facilitated using values of the equilibrium potentials of these transitions, as well as their relative spacing. As the interaction free energies between the redox centres scale linearly with overall ring charge and in conjunction with fast intramolecular electron transfer (˜107 s-1), these molecules can be considered as uniformly charged nanorings (diameter ˜1-2 nm).

  19. Oligomeric ferrocene rings

    NASA Astrophysics Data System (ADS)

    Inkpen, Michael S.; Scheerer, Stefan; Linseis, Michael; White, Andrew J. P.; Winter, Rainer F.; Albrecht, Tim; Long, Nicholas J.

    2016-09-01

    Cyclic oligomers comprising strongly interacting redox-active monomer units represent an unknown, yet highly desirable class of nanoscale materials. Here we describe the synthesis and properties of the first family of molecules belonging to this compound category—differently sized rings comprising only 1,1‧-disubstituted ferrocene units (cyclo[n], n = 5–7, 9). Due to the close proximity and connectivity of centres (covalent Cp–Cp linkages; Cp = cyclopentadienyl) solution voltammograms exhibit well-resolved, separated 1e– waves. Theoretical interrogations into correlations based on ring size and charge state are facilitated using values of the equilibrium potentials of these transitions, as well as their relative spacing. As the interaction free energies between the redox centres scale linearly with overall ring charge and in conjunction with fast intramolecular electron transfer (∼107 s‑1), these molecules can be considered as uniformly charged nanorings (diameter ∼1–2 nm).

  20. Child sex rings.

    PubMed

    Wild, N J; Wynne, J M

    1986-07-19

    Details of 11 child sex rings identified in one working class community were obtained by interviewing investigating police officers and examining health and social services records. The rings contained 14 adult male perpetrators and 175 children aged 6-15 years. Most perpetrators used child ringleaders to recruit victims; others became a "family friend" or obtained a position of authority over children. Secrecy was encouraged and bribery, threats, and peer pressure used to induce participation in sexual activities. Offences reported included fondling, masturbation, pornography, and oral, vaginal, and anal intercourse. Eleven perpetrators were successfully prosecuted; all but one received a sentence of three years or less. Behavioural problems were common among those children who had participated for a long time. Child sex rings are difficult to detect and may be common. Many children are seriously abused as a consequence of them. PMID:3730803

  1. Rings dominate western Gulf

    NASA Astrophysics Data System (ADS)

    Vidal L., Francisco V.; Vidal L., Victor M. V.; Molero, José María Pérez

    Surface and deep circulation of the central and western Gulf of Mexico is controlled by interactions of rings of water pinched from the gulf's Loop Current. The discovery was made by Mexican oceanographers who are preparing a full-color, 8-volume oceanographic atlas of the gulf.Anticyclonic warm-core rings pinch off the Loop Current at a rate of about one to two per year, the scientists of the Grupo de Estudios Oceanográficos of the Instituto de Investigaciones Eléctricas (GEO-IIE) found. The rings migrate west until they collide with the continental shelf break of the western gulf, almost always between 22° and 23°N latitude. On their westward travel they transfer angular momentum and vorticity to the surrounding water, generating cyclonic circulations and vortex pairs that completely dominate the entire surface and deep circulation of the central and western gulf.

  2. Stable CSR in storage rings: A model

    SciTech Connect

    Sannibale, Fernando; Byrd, John M.; Loftsdottir, Agusta; Venturini, Marco; Abo-Bakr, Michael; Feikes, Jorge; Holldack, Karsten; Kuske, Peter; Wustefeld, Godehart; Hubers, Heinz-Willerm; Warnock, Robert

    2005-01-03

    A comprehensive historical view of the work done on coherent synchrotron radiation (CSR) in storage rings is given in reference [1]. Here we want just to point out that even if the issue of CSR in storage rings was already discussed over 50 years ago, it is only recently that a considerable number of observations have been reported. In fact, intense bursts of coherent synchrotron radiation with a stochastic character were measured in the terahertz frequency range, at several synchrotron light source storage rings [2-8]. It has been shown [8-11], that this bursting emission of CSR is associated with a single bunch instability, usually referred as microbunching instability (MBI), driven by the fields of the synchrotron radiation emitted by the bunch itself. Of remarkably different characteristics was the CSR emission observed at BESSY II in Berlin, when the storage ring was tuned into a special low momentum compaction mode [12, 13]. In fact, the emitted radiation was not the quasi-random bursting observed in the other machines, but a powerful and stable flux of broadband CSR in the terahertz range. This was an important result, because it experimentally demonstrated the concrete possibility of constructing a stable broadband source with extremely high power in the terahertz region. Since the publication of the first successful experiment using the ring as a CSR source [14], BESSY II has regular scheduled user s shifts dedicated to CSR experiments. At the present time, several other laboratories are investigating the possibility of a CSR mode of operation [15-17] and a design for a new ring optimized for CSR is at an advanced stage [18]. In what follows, we describe a model that first accounts for the BESSY II observations and then indicates that the special case of BESSY II is actually quite general and typical when relativistic electron storage rings are tuned for short bunches. The model provides a scheme for predicting and optimizing the performance of ring

  3. Trials point to effectiveness of new vaginal ring.

    PubMed

    1982-02-01

    Results of a large multicentered clinical trial of a new contraceptive vaginal ring show that the new ring may be about as effective as oral contraceptives but with fewer side effects. The ring, which is a little smaller than a 75 mm diaphragm and has a Silastic inner core and outer tubing, is avilable in 2 sizes (50 mm or 58 mm) and contains a middle layer with a steroid mixture of estrogen and progestin. Both types of ring contain about 100 mg levonorgestrel and 50 mg estradiol. Ovulation is suppressed by the steroids in the ring. The ring is placed in the vagina for about 3 weeks and then removed for 1 week. Withdrawal bleeding occurs when the ring is removed. Comparative studies of the effectiveness of the ring and a pill (Nordette, which contains 150 mcg levonorgestrel and 30 mcg estradiol) show that after a year's use, both type of contraceptives had a pregnancy rate of about 3 pregnancies per 100 users. Ring users had higher continuation rates than pill users (50/100 women for the ring vs. 30/100 for the pill). Reasons for discontinuation for the ring include occurrence of vaginal discharge, vaginitis, and menstrual problems. Ring users had lesser incidence of nausea and headache compared to pill users; they also did not experience an increase in angiotensinogen levels or blood pressure. Another advantage of the ring is its once-a-month administration. Investigators are still testing the best method for using the ring. However, as testing is not yet complete, application for approval by the Food and Drug Administration may take quite some time.

  4. Sliding-Ring Catenanes.

    PubMed

    Fernando, Isurika R; Frasconi, Marco; Wu, Yilei; Liu, Wei-Guang; Wasielewski, Michael R; Goddard, William A; Stoddart, J Fraser

    2016-08-17

    Template-directed protocols provide a routine approach to the synthesis of mechanically interlocked molecules (MIMs), in which the mechanical bonds are stabilized by a wide variety of weak interactions. In this Article, we describe a strategy for the preparation of neutral [2]catenanes with sliding interlocked electron-rich rings, starting from two degenerate donor-acceptor [2]catenanes, consisting of a tetracationic cyclobis(paraquat-p-phenylene) cyclophane (CBPQT(4+)) and crown ethers containing either (i) hydroquinone (HQ) or (ii) 1,5-dioxynaphthalene (DNP) recognition units and carrying out four-electron reductions of the cyclophane components to their neutral forms. The donor-acceptor interactions between the CBPQT(4+) ring and both HQ and DNP units present in the crown ethers that stabilize the [2]catenanes are weakened upon reduction of the cyclophane components to their radical cationic states and are all but absent in their fully reduced states. Characterization in solution performed by UV-vis, EPR, and NMR spectroscopic probes reveals that changes in the redox properties of the [2]catenanes result in a substantial decrease of the energy barriers for the circumrotation and pirouetting motions of the interlocked rings, which glide freely through one another in the neutral states. The solid-state structures of the fully reduced catenanes reveal profound changes in the relative dispositions of the interlocked rings, with the glycol chains of the crown ethers residing in the cavities of the neutral CBPQT(0) rings. Quantum mechanical investigations of the energy levels associated with the four different oxidation states of the catenanes support this interpretation. Catenanes and rotaxanes with sliding rings are expected to display unique properties. PMID:27398609

  5. Reaction Studies with Exotic Nuclei in Storage Rings

    SciTech Connect

    Muenzenberg, Gottfried; Schrieder, Gerhard

    2000-12-31

    The first experiments to explore nuclear ground-state properties of exotic nuclei with heavy-ion storage rings have already proved the research potential of precision experiments with the new experimental technique. In this contribution the perspectives for reaction studies in storage rings with energetic exotic nuclei at internal targets and in a small electron -- heavy ion collider are addressed. The feasibility of such experiments is discussed.

  6. Ring laser gyroscope anode

    SciTech Connect

    Ljung, B.H.

    1981-03-17

    An anode for a ring laser gyroscope which provides improved current stability in the glow discharge path is disclosed. The anode of this invention permits operation at lower currents thereby allowing a reduction of heat dissipation in the ring laser gyroscope. The anode of one embodiment of this invention is characterized by a thumbtack appearance with a spherical end where the normal sharp end of the thumbtack would be located. The stem of the anode extends from the outside of the gyroscope structure to the interior of the structure such that the spherical end is substantially adjacent to the laser beam.

  7. The covariant chiral ring

    NASA Astrophysics Data System (ADS)

    Bourget, Antoine; Troost, Jan

    2016-03-01

    We construct a covariant generating function for the spectrum of chiral primaries of symmetric orbifold conformal field theories with N = (4 , 4) supersymmetry in two dimensions. For seed target spaces K3 and T 4, the generating functions capture the SO(21) and SO(5) representation theoretic content of the chiral ring respectively. Via string dualities, we relate the transformation properties of the chiral ring under these isometries of the moduli space to the Lorentz covariance of perturbative string partition functions in flat space.

  8. GUARD RING SEMICONDUCTOR JUNCTION

    DOEpatents

    Goulding, F.S.; Hansen, W.L.

    1963-12-01

    A semiconductor diode having a very low noise characteristic when used under reverse bias is described. Surface leakage currents, which in conventional diodes greatly contribute to noise, are prevented from mixing with the desired signal currents. A p-n junction is formed with a thin layer of heavily doped semiconductor material disposed on a lightly doped, physically thick base material. An annular groove cuts through the thin layer and into the base for a short distance, dividing the thin layer into a peripheral guard ring that encircles the central region. Noise signal currents are shunted through the guard ring, leaving the central region free from such currents. (AEC)

  9. Unidirectional ring lasers

    DOEpatents

    Hohimer, John P.; Craft, David C.

    1994-01-01

    Unidirectional ring lasers formed by integrating nonreciprocal optical elements into the resonant ring cavity. These optical elements either attenuate light traveling in a nonpreferred direction or amplify light traveling in a preferred direction. In one preferred embodiment the resonant cavity takes the form of a circle with an S-shaped crossover waveguide connected to two points on the interior of the cavity such that light traveling in a nonpreferred direction is diverted from the cavity into the crossover waveguide and reinjected out of the other end of the crossover waveguide into the cavity as light traveling in the preferred direction.

  10. Unidirectional ring lasers

    DOEpatents

    Hohimer, J.P.; Craft, D.C.

    1994-09-20

    Unidirectional ring lasers formed by integrating nonreciprocal optical elements into the resonant ring cavity is disclosed. These optical elements either attenuate light traveling in a nonpreferred direction or amplify light traveling in a preferred direction. In one preferred embodiment the resonant cavity takes the form of a circle with an S-shaped crossover waveguide connected to two points on the interior of the cavity such that light traveling in a nonpreferred direction is diverted from the cavity into the crossover waveguide and reinjected out of the other end of the crossover waveguide into the cavity as light traveling in the preferred direction. 21 figs.

  11. Saturn's Rings, the Yarkovsky Effects, and the Ring of Fire

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    2004-01-01

    The dimensions of Saturn's A and B rings may be determined by the seasonal Yarkovsky effect and the Yarkovsky-Schach effect; the two effects confine the rings between approximately 1.68 and approximately 2.23 Saturn radii, in reasonable agreement with the observed values of 1.525 and 2.267. The C ring may be sparsely populated because its particles are transients on their way to Saturn; the infall may create a luminous Ring of Fire around Saturn's equator. The ring system may be young: in the past heat flow from Saturn's interior much above its present value would not permit rings to exist.

  12. The endcap Cherenkov ring imaging detector at SLD

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hawegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dolinsky, S.

    1995-05-01

    The authors present the Cherenkov Ring Imaging Detector in the endcap regions of the SLD detector and report initial performance. The endcap CRID was completed and commissioned in 1993 and is fully operational for the 1994 run. First Cherenkov rings have been observed. The endcap CRID detectors and fluid systems are described and initial operational experience is discussed.

  13. Prediscovery evidence of planetary rings

    NASA Technical Reports Server (NTRS)

    Mclaughlin, W. I.

    1980-01-01

    The discoveries of the Uranian and Jovian ring systems were surprising events to most of the scientific community. However, as far back as 1787 reports of observations of rings about a planet other than Saturn were made; Herschel, the discoverer of Uranus, thought he had detected rings about that planet on several occasions. Although Herschel's observations were almost certainly due to defects in the optical system of his telescope, several valid observations and predictions have been made in the last two hundred years. This paper focuses on such prediscovery evidence for the Uranian and Jovian rings and for the newly designated F ring of Saturn. Some new work of the author on the structure of the Saturnian rings is included which is relevant to the F ring. The prospects for rings about Neptune and Pluto and a ring close to the Sun are also reviewed. The relevance of the prediscovery evidence to aspects of scientific methodology is discussed.

  14. Storage ring mass spectrometry for nuclear structure and astrophysics research

    NASA Astrophysics Data System (ADS)

    Zhang, Y. H.; Litvinov, Yu A.; Uesaka, T.; Xu, H. S.

    2016-07-01

    In the last two and a half decades ion storage rings have proven to be powerful tools for precision experiments with unstable nuclides in the realm of nuclear structure and astrophysics. There are presently three storage ring facilities in the world at which experiments with stored radioactive ions are possible. These are the ESR in GSI, Darmstadt/Germany, the CSRe in IMP, Lanzhou/China, and the R3 storage ring in RIKEN, Saitama/Japan. In this work, an introduction to the facilities is given. Selected characteristic experimental results and their impact in nuclear physics and astrophysics are presented. Planned technical developments and the envisioned future experiments are outlined.

  15. On the evolution of vortex rings with swirl

    SciTech Connect

    Naitoh, Takashi; Okura, Nobuyuki; Gotoh, Toshiyuki; Kato, Yusuke

    2014-06-15

    A laminar vortex ring with swirl, which has the meridional velocity component inside the vortex core, was experimentally generated by the brief fluid ejection from a rotating outlet. The evolution of the vortex ring was investigated with flow visualizations and particle image velocimetry measurements in order to find the influence of swirling flow in particular upon the transition to turbulence. Immediately after the formation of a vortex ring with swirl, a columnar strong vortex along the symmetric axis is observed in all cases of the present experiment. Then the characteristic fluid discharging from a vortex ring with swirl referred to as “peeling off” appears. The amount of discharging fluid due to the “peeling off” increases with the angular velocity of the rotating outlet. We conjectured that the mechanism generating the “peeling off” is related to the columnar strong vortex by close observations of the spatio-temporal development of the vorticity distribution and the cutting 3D images constructed from the successive cross sections of a vortex ring. While a laminar vortex ring without swirl may develop azimuthal waves around its circumference at some later time and the ring structure subsequently breaks, the swirling flow in a vortex ring core reduces the amplification rate of the azimuthal wavy deformation and preserved its ring structure. Then the traveling distance of a vortex ring can be extended using the swirl flow under certain conditions.

  16. Flushing Ring for EDM

    NASA Technical Reports Server (NTRS)

    Earwood, L.

    1985-01-01

    Removing debris more quickly lowers cutting time. Operation, cutting oil and pressurized air supplied to ring placed around workpiece. Air forces oil through small holes and agitates oil as it flows over workpiece. High flow rate and agitation dislodge and remove debris. Electrical discharge removes material from workpiece faster.

  17. Ring of Stellar Death

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This false-color image from NASA's Spitzer Space Telescope shows a dying star (center) surrounded by a cloud of glowing gas and dust. Thanks to Spitzer's dust-piercing infrared eyes, the new image also highlights a never-before-seen feature -- a giant ring of material (red) slightly offset from the cloud's core. This clumpy ring consists of material that was expelled from the aging star.

    The star and its cloud halo constitute a 'planetary nebula' called NGC 246. When a star like our own Sun begins to run out of fuel, its core shrinks and heats up, boiling off the star's outer layers. Leftover material shoots outward, expanding in shells around the star. This ejected material is then bombarded with ultraviolet light from the central star's fiery surface, producing huge, glowing clouds -- planetary nebulas -- that look like giant jellyfish in space.

    In this image, the expelled gases appear green, and the ring of expelled material appears red. Astronomers believe the ring is likely made of hydrogen molecules that were ejected from the star in the form of atoms, then cooled to make hydrogen pairs. The new data will help explain how planetary nebulas take shape, and how they nourish future generations of stars.

    This image composite was taken on Dec. 6, 2003, by Spitzer's infrared array camera, and is composed of images obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

  18. Reading, Writing, and Rings!

    ERIC Educational Resources Information Center

    Aschbacher, Pamela; Li, Erika; Hammon, Art

    2008-01-01

    "Reading, Writing, and Rings!" was created by a team of elementary teachers, literacy experts, and scientists in order to integrate science and literacy. These free units bring students inside NASA's Cassini-Huygens mission to Saturn. The authors--a science teacher and education outreach specialist and two evaluators of educational programs--have…

  19. Ring laser scatterometer

    SciTech Connect

    Ackermann, Mark; Diels, Jean-Claude

    2005-06-28

    A scatterometer utilizes the dead zone resulting from lockup caused by scatter from a sample located in the optical path of a ring laser at a location where counter-rotating pulses cross. The frequency of one pulse relative to the other is varied across the lockup dead zone.

  20. Design Considerations for High Energy Electron -- Positron Storage Rings

    DOE R&D Accomplishments Database

    Richter, B.

    1966-11-01

    High energy electron-positron storage rings give a way of making a new attack on the most important problems of elementary particle physics. All of us who have worked in the storage ring field designing, building, or using storage rings know this. The importance of that part of storage ring work concerning tests of quantum electrodynamics and mu meson physics is also generally appreciated by the larger physics community. However, I do not think that most of the physicists working tin the elementary particle physics field realize the importance of the contribution that storage ring experiments can make to our understanding of the strongly interacting particles. I would therefore like to spend the next few minutes discussing the sort of things that one can do with storage rings in the strongly interacting particle field.

  1. Neptune may have polar rings

    NASA Astrophysics Data System (ADS)

    Dobrovolskis, A. R.; Steiman-Cameron, T. Y.; Borderies, N. J.

    1989-08-01

    Perturbations from Neptune's highly inclined satellite Triton can maintain rings passing nearly over Neptune's poles. These hypothetical polar rings are nearly perpendicular to Triton's orbit as well, and lie within several degrees of the plane of Voyager II's trajectory through the Neptunian system. Polar rings can coexist with equatorial rings at different radii. A randomly oriented torus of debris around Neptune has a probability of several percent to settle into a polar ring. Voyager II stands a significant chance of encountering a polar ring.

  2. Narrow rings - Observations and theory

    NASA Astrophysics Data System (ADS)

    Porco, C. C.

    Voyager 1 and 2 observations have revealed that within the rings of Saturn lies a set of narrow, eccentric rings resembling those of Uranus. Voyager 2 observations have proven crucial in refining the Uranian ring orbit models to a remarkable level of precision. All these rings share some common structural and kinematical characteristics, such as spatially variable radial widths and uniform precession; however, interesting differences exist which provoke attention and may be related to the differing dynamical environments in which these rings dwell. The current state of the knowledge of the shape, behavior, and confinement of narrow rings is discussed.

  3. Bunch coalescing in the Fermilab Main Ring

    SciTech Connect

    Wildman, D.; Martin, P.; Meisner, K.; Miller, H.W.

    1987-03-01

    A new rf system has been installed in the Fermilab Main Ring to coalesce up to 13 individual bunches of protons or antiprotons into a single high-intensity bunch. The coalescing process consists of adiabatically reducing the h = 1113 Main Ring rf voltage from 1 MV to less than 1 kV, capturing the debunched beam in a linearized h = 53 and h = 106 bucket, rotating for a quarter of a synchrotron oscillation period, and then recapturing the beam in a single h = 1113 bucket. The new system will be described and the results of recent coalescing experiments will be compared with computer-generated particle tracking simulations.

  4. Prospect of polarized targets in electron rings

    SciTech Connect

    Holt, R.J.

    1984-01-01

    The feasibility of performing electron scattering experiments with polarized targets in electron storage rings is discussed. Three examples of the physics which would be accessible with this novel method are given. It is noted that this new method is compatible with recent proposals for linac-stretcher-ring accelerator designs. A new method for producing a polarized hydrogen or deuterium target is proposed and some preliminary results are described. A brief summary of laser-driven polarized targets as well as conventionally-produced polarized atomic beams is included.

  5. Wall reflection of a viscous vortex ring

    NASA Technical Reports Server (NTRS)

    Sa, J. Y.; Chang, K. S.; Liu, C. H.

    1986-01-01

    The behavior of a viscous axisymmetric vortex ring being reflected from a wall is investigated. The incompressible Navier-Stokes equations formulated in terms of the vorticity function and vector potential are numerically integrated by implicit finite difference methods. To specify the vector potential at a far boundary from the wall, the existing integral method used so far only for an unbounded domain is modified by a kind of image method. The trajectory of the vortex ring calcualted as a result closely resembles that observable from the experiment.

  6. The BRAHMS ring imaging Cherenkov detector

    NASA Astrophysics Data System (ADS)

    Debbe, R.; Jørgensen, C. E.; Olness, J.; Yin, Z.

    2007-01-01

    A Ring Imaging Cherenkov detector built for the BRAHMS experiment at the Brookhaven RHIC is described. This detector has a high index of refraction gas radiator. Cherenkov light is focused on a photo-multiplier based photon detector with a large spherical mirror. The combination of momentum and ring radius measurement provides particle identification from 2.5 to 35 GeV/ c for pions and kaons and well above 40 GeV/ c for protons during runs that had the radiator index of refraction set at n-1=1700×10-6.

  7. Status of the Mini-Ring project: a compact electrostatic storage ring

    SciTech Connect

    Bernard, J.; Montagne, G.; Ales, J.; Bredy, R.; Chen, L.; Martin, S.; Cederquist, H.; Schmidt, H.

    2008-12-08

    The idea of building a small, cheap and transportable electrostatic storage ring emerged in the Lyon and Stockholm groups as a collaborative work in the framework of the ITS-LEIF European network. Such a ring could be devoted to experiments where the ring needs to be transported to different facilities that can deliver exotic particles or means of excitation (e.-g. highly charged ions, X--ray synchrotron...). The design of the so-called Mini-Ring and ion trajectory simulations will be presented. First preliminary results have demonstrated the storage of stable Ar{sup +} ion beams in the millisecond time range. The storage time is presently limited by the poor vacuum conditions (P = 2x10{sup -7} mbar) in the chamber, a feature that is going to be improved in the future.

  8. Ring Bubbles of Dolphins

    NASA Technical Reports Server (NTRS)

    Shariff, Karim; Marten, Ken; Psarakos, Suchi; White, Don J.; Merriam, Marshal (Technical Monitor)

    1996-01-01

    The article discusses how dolphins create and play with three types of air-filled vortices. The underlying physics is discussed. Photographs and sketches illustrating the dolphin's actions and physics are presented. The dolphins engage in this behavior on their own initiative without food reward. These behaviors are done repeatedly and with singleminded effort. The first type is the ejection of bubbles which, after some practice on the part of the dolphin, turn into toroidal vortex ring bubbles by the mechanism of baroclinic torque. These bubbles grow in radius and become thinner as they rise vertically to the surface. One dolphin would blow two in succession and guide them to fuse into one. Physicists call this a vortex reconnection. In the second type, the dolphins first create an invisible vortex ring in the water by swimming on their side and waving their tail fin (also called flukes) vigorously. This vortex ring travels horizontally in the water. The dolphin then turns around, finds the vortex and injects a stream of air into it from its blowhole. The air "fills-out" the core of the vortex ring. Often, the dolphin would knock-off a smaller ring bubble from the larger ring (this also involves vortex reconnection) and steer the smaller ring around the tank. One other dolphin employed a few other techniques for planting air into the fluke vortex. One technique included standing vertically in the water with tail-up, head-down and tail piercing the free surface. As the fluke is waved to create the vortex ring, air is entrained from above the surface. Another technique was gulping air in the mouth, diving down, releasing air bubbles from the mouth and curling them into a ring when they rose to the level of the fluke. In the third type, demonstrated by only one dolphin, the longitudinal vortex created by the dorsal fin on the back is used to produce 10-15 foot long helical bubbles. In one technique she swims in a curved path. This creates a dorsal fin vortex since

  9. Noncircular features in Saturn's rings II: The C ring

    NASA Astrophysics Data System (ADS)

    Nicholson, Philip D.; French, Richard G.; McGhee-French, Colleen A.; Hedman, Matthew M.; Marouf, Essam A.; Colwell, Joshua E.; Lonergan, Katherine; Sepersky, Talia

    2014-10-01

    We present a comprehensive survey of sharp-edged features in Saturn's C ring, using data from radio and stellar occultation experiments carried out by the Cassini spacecraft over a period of more than five years. Over 100 occultations are included in the combined data set, enabling us to identify systematic radial perturbations as small as 200 m on the edges of ringlets and gaps. We systematically examine all of the noncircular features in the C ring, refine the eccentricities, precession rates and width variations of the known eccentric ringlets, identify connections between several noncircular gap and ringlet edges and nearby satellite resonances, and report the discovery of a host of free normal modes on ring and gap edges. We confirm a close association between the Titan (or Colombo) ringlet (a = 77878.7 km) and the Titan 1:0 apsidal resonance: the apoapse of the ringlet is nearly aligned with Titan's mean longitude, and the pattern speed closely matches Titan's mean motion. Similar forced perturbations associated with the Titan resonance are detectable in more than two dozen other features located throughout the inner C ring as far as 3500 km from the Titan resonance. The inner edge of the Titan ringlet exhibits several strong outer Lindblad resonance (OLR-type) normal modes, and scans of the outer edge reveal inner Lindblad resonance (ILR-type) normal modes. The Maxwell ringlet (a = 87,510 km), in contrast, appears to be a freely-precessing eccentric ringlet, with post-fit RMS residuals for the inner and outer edges of only 0.23 and 0.16 km, respectively. The best-fitting edge precession rates differ by over 10 times the estimated uncertainty in the rate of the inner edge, consistent with a slow libration about an equilibrium configuration on a decadal timescale. Using self-gravity models for ringlet apse alignment, we estimate the masses and surface densities of the Titan and Maxwell ringlets. The Bond ringlet (a = 88,710 km), about 17 km wide, shows no free

  10. Saturn ring temperature changes before and after ring equinox

    NASA Astrophysics Data System (ADS)

    Spilker, Linda; Flandes, Alberto; Morishima, Ryuji; Leyrat, Cedric; Altobelli, Nicolas; Ferrari, Cecile; Brooks, Shawn; Pilorz, Stu

    2010-05-01

    The Cassini Composite infrared spectrometer (CIRS) retrieved the temperatures of Saturn's main rings at solar elevations ranging from 24 degrees to zero degrees at equinox (August 2009) as the sun traversed from the south to north side of the rings. Over this broad range of solar elevation the CIRS data show that the ring temperatures vary as much as 29K- 38K for the A ring, 22K-34K for the B ring and 18K-23K for the C ring. Interestingly the unlit sides of the rings show a similar decrease in temperature with the decreasing solar elevation. As equinox approached, the main rings cooled to their lowest temperatures measured to date. At equinox the solar input is very small and the primary heat sources for the rings are Saturn thermal and visible energy. Temperatures are almost identical for similar geometries on the north and south sides of the rings. The ring temperatures at equinox were: C ring, 55-75 K; B ring, 45-60 K; Cassini Division, 45 - 58 K; and A ring, 43 - 52 K. After Saturn equinox the solar elevation angle began to increase again and the temperatures on both the lit (north) and unlit (south) sides of the rings have begun to increase as well. Ring thermal models developed by Flandes and Morishima are able to reproduce most of the equinox temperatures observed by CIRS. Results before and after equinox will be presented. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA and at CEA Saclay supported by the "Programme National de Planetologie". Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

  11. On the propagation and decay of North Brazil Current rings

    NASA Astrophysics Data System (ADS)

    Jochumsen, Kerstin; Rhein, Monika; Hüttl-Kabus, Sabine; BöNing, Claus W.

    2010-10-01

    Near the western boundary of the tropical North Atlantic, where the North Brazil Current (NBC) retroflects into the North Equatorial Countercurrent, large anticyclonic rings are shed. After separating from the retroflection region, the so-called NBC rings travel northwestward along the Brazilian coast, until they reach the island chain of the Lesser Antilles and disintegrate. These rings contribute substantially to the upper limb return flow of the Atlantic Meridional Overturning Circulation by carrying South Atlantic Water into the northern subtropical gyre. Their relevance for the northward transport of South Atlantic Water depends on the frequency of their generation as well as on their horizontal and vertical structure. The ring shedding and propagation and the complex interaction of the rings with the Lesser Antilles are investigated in the ? Family of Linked Atlantic Model Experiments (FLAME) model. The ring properties simulated in FLAME reach the upper limit of the observed rings in diameter and agree with recent observations on seasonal variability, which indicates a maximum shedding during the first half of the year. When the rings reach the shallow topography of the Lesser Antilles, they are trapped by the island triangle of St. Lucia, Barbados and Tobago and interact with the island chain. The model provides a resolution that is capable of resolving the complex topographic conditions at the islands and illuminates various possible fates for the water contained in the rings. It also reproduces laboratory experiments that indicate that both cyclones and anticyclones are formed after a ring passes through a topographic gap. Trajectories of artificial floats, which were inserted into the modeled velocity field, are used to investigate the pathways of the ring cores and their fate after they encounter the Lesser Antilles. The majority of the floats entered the Caribbean, while the northward Atlantic pathway was found to be of minor importance. No prominent

  12. Cassini First Diametric Radio Occultation of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Marouf, E.; French, R.; Rappaport, N.; Kliore, A.; Flasar, M.; Nagy, A.; Ambrosini, R.; McGhee, C.; Schinder, P.; Anabtawi, A.; Barbinis, E.; Goltz, G.; Thomson, F.; Wong, K.

    2005-05-01

    We present preliminary results expected from the first planned Cassini radio occultation observation of Saturn's rings, to be conducted on May 3rd, 2005. The path of Cassini as seen from Earth (the occultation track) has been designed to cross the rings from the west to the east ansa almost diametrically, allowing for occultation of all major ring features at two widely separated longitudes (about 180 deg apart). The duration of the geometric occultation is about 1.5 hours on each side. During the occultation, Cassini transmits through the rings three coherent monochromatic radio signals of wavelength 0.94, 3.6, and 13 cm (Ka-, X-, and S-band respectively), a capability unique to Cassini. The perturbed signals received at the Earth are recorded at the NASA DSN complexes at Goldstone and Canberra. Both direct and forward-scattered components of the signal may be identified in spectrograms of the received signals. The time history of the extinction of the direct signal is expected to yield high-spatial-resolution optical depth and phase shift profiles of ring structure. The timing of the occultation was optimized to allow probing the rings when the ring-opening-angle B (the angle between the line-of-sight and the ring plane) is relatively large (B = 23 deg), hence maximizing chances of measuring for the first time the structure of the relatively optically thick Ring B. In a similar experiment by Voyager in 1980, excessive signal attenuation along the long path within the nearly closed rings (B = 5.9 deg) limited the utility of the observations in relatively thick ring regions, in particular the main Ring B. For the Cassini optimized occultation geometry, a large B, slow radial velocity along the occultation track, and much improved phase stability of the reference ultrastable oscillator (USO) on board Cassini combine to promise achievable radial resolution approaching 100 m over a good fraction of the rings. Measurement of the amplitude and phase of the diffracted

  13. Beam Diagnostics of the Small Isochronous Ring

    SciTech Connect

    Felix Marti; Eduard Pozdeyev

    2004-07-01

    The purpose of this paper is to describe the beam diagnostic systems in the Small Isochronous Ring (SIR) developed and built at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). SIR is a small-scale experiment that simulates the dynamics of intense beams in large accelerators. A 20 to 30 keV hydrogen or deuterium ion bunch is injected in the ring, extracted after a variable number of turns and its longitudinal profile is studied. Some of the diagnostic tools available in SIR include an emittance measurement system in the injection line, scanning wires in different sections of the ring, phosphor screens at the injection and extraction points and a fast Faraday cup in the extraction line. The design of these systems and the kind of beam information they provide are discussed in detail.

  14. Control System of the Small Isochronous ring

    SciTech Connect

    Felix Marti; Eduard Pozdeyev

    2004-07-01

    The purpose of this paper is to describe the control system of the Small Isochronous Ring (SIR) developed and built at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). SIR is a small-scale experiment that simulates the dynamics of intense beams in large accelerators. A 20 to 30 keV hydrogen or deuterium ion bunch is injected in the ring, extracted after a variable number of turns and its longitudinal profile is studied. Information about the electronics used and software written to control different injection line, ring and extraction line elements is included. Some of these elements are magnets, electrostatic quadrupoles, electric and magnetic correctors, scanning wires, emittance measurement system, chopper and a fast Faraday cup.

  15. The cryogenic storage ring CSR.

    PubMed

    von Hahn, R; Becker, A; Berg, F; Blaum, K; Breitenfeldt, C; Fadil, H; Fellenberger, F; Froese, M; George, S; Göck, J; Grieser, M; Grussie, F; Guerin, E A; Heber, O; Herwig, P; Karthein, J; Krantz, C; Kreckel, H; Lange, M; Laux, F; Lohmann, S; Menk, S; Meyer, C; Mishra, P M; Novotný, O; O'Connor, A P; Orlov, D A; Rappaport, M L; Repnow, R; Saurabh, S; Schippers, S; Schröter, C D; Schwalm, D; Schweikhard, L; Sieber, T; Shornikov, A; Spruck, K; Sunil Kumar, S; Ullrich, J; Urbain, X; Vogel, S; Wilhelm, P; Wolf, A; Zajfman, D

    2016-06-01

    An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm(-3) is derived, equivalent to a room-temperature pressure below 10(-14) mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams.

  16. The cryogenic storage ring CSR

    NASA Astrophysics Data System (ADS)

    von Hahn, R.; Becker, A.; Berg, F.; Blaum, K.; Breitenfeldt, C.; Fadil, H.; Fellenberger, F.; Froese, M.; George, S.; Göck, J.; Grieser, M.; Grussie, F.; Guerin, E. A.; Heber, O.; Herwig, P.; Karthein, J.; Krantz, C.; Kreckel, H.; Lange, M.; Laux, F.; Lohmann, S.; Menk, S.; Meyer, C.; Mishra, P. M.; Novotný, O.; O'Connor, A. P.; Orlov, D. A.; Rappaport, M. L.; Repnow, R.; Saurabh, S.; Schippers, S.; Schröter, C. D.; Schwalm, D.; Schweikhard, L.; Sieber, T.; Shornikov, A.; Spruck, K.; Sunil Kumar, S.; Ullrich, J.; Urbain, X.; Vogel, S.; Wilhelm, P.; Wolf, A.; Zajfman, D.

    2016-06-01

    An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm-3 is derived, equivalent to a room-temperature pressure below 10-14 mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams.

  17. The cryogenic storage ring CSR.

    PubMed

    von Hahn, R; Becker, A; Berg, F; Blaum, K; Breitenfeldt, C; Fadil, H; Fellenberger, F; Froese, M; George, S; Göck, J; Grieser, M; Grussie, F; Guerin, E A; Heber, O; Herwig, P; Karthein, J; Krantz, C; Kreckel, H; Lange, M; Laux, F; Lohmann, S; Menk, S; Meyer, C; Mishra, P M; Novotný, O; O'Connor, A P; Orlov, D A; Rappaport, M L; Repnow, R; Saurabh, S; Schippers, S; Schröter, C D; Schwalm, D; Schweikhard, L; Sieber, T; Shornikov, A; Spruck, K; Sunil Kumar, S; Ullrich, J; Urbain, X; Vogel, S; Wilhelm, P; Wolf, A; Zajfman, D

    2016-06-01

    An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm(-3) is derived, equivalent to a room-temperature pressure below 10(-14) mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams. PMID:27370434

  18. Inorganic glass ceramic slip rings

    NASA Technical Reports Server (NTRS)

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  19. Analysis of ionic photofragments stored in an electrostatic storage ring.

    PubMed

    Svendsen, Annette; Teiwes, Ricky; Kiefer, Hjalte V; Andersen, Lars H; Pedersen, Henrik B

    2016-01-01

    A new method to analyze the properties of fragment ions created in storage ring experiments is presented. The technique relies on an acceleration of ionic fragments immediately after production whereby the fragments are stored in the storage ring. To obtain a fragment mass spectrum, the storage ring is exploited as an electrostatic analyzer (ESA) in which case the number of stored fragment ions is recorded as a function of the applied acceleration potential. However, the storage ring can additionally be employed as a time-of-flight (TOF) instrument by registering the temporal distribution of fragment ions. It is demonstrated that the combined ESA-TOF operation of the ring allows not only to determine fragment masses with much better resolution compared to the ESA mode alone but also enables the extraction of detailed information on the fragmentation dynamics. The method is described analytically and verified with photodissociation experiments on stored Cl2 (-) at an excitation wavelength of 530 nm. PMID:26827313

  20. Analysis of ionic photofragments stored in an electrostatic storage ring

    NASA Astrophysics Data System (ADS)

    Svendsen, Annette; Teiwes, Ricky; Kiefer, Hjalte V.; Andersen, Lars H.; Pedersen, Henrik B.

    2016-01-01

    A new method to analyze the properties of fragment ions created in storage ring experiments is presented. The technique relies on an acceleration of ionic fragments immediately after production whereby the fragments are stored in the storage ring. To obtain a fragment mass spectrum, the storage ring is exploited as an electrostatic analyzer (ESA) in which case the number of stored fragment ions is recorded as a function of the applied acceleration potential. However, the storage ring can additionally be employed as a time-of-flight (TOF) instrument by registering the temporal distribution of fragment ions. It is demonstrated that the combined ESA-TOF operation of the ring allows not only to determine fragment masses with much better resolution compared to the ESA mode alone but also enables the extraction of detailed information on the fragmentation dynamics. The method is described analytically and verified with photodissociation experiments on stored Cl 2- at an excitation wavelength of 530 nm.

  1. Oscillating pendulum decay by emission of vortex rings.

    PubMed

    Bolster, Diogo; Hershberger, Robert E; Donnelly, Russell J

    2010-04-01

    We have studied oscillation of a pendulum in water using spherical bobs. By measuring the loss in potential energy, we estimate the drag coefficient on the sphere and compare to data from liquid-helium experiments. The drag coefficients compare very favorably illustrating the true scaling behavior of this phenomenon. We also studied the decay of amplitude of the pendulum over time. As observed previously, at small amplitudes, the drag on the bob is given by the linear Stokes drag and the decay is exponential. For larger amplitudes, the pendulum bob sheds vortex rings as it reverses direction. The momentum imparted to these vortex rings results in an additional discrete drag on the bob. We present experiments and a theoretical estimate of this vortex-ring-induced drag. We analytically derive an estimate for a critical amplitude beyond which vortex ring shedding will occur as well as an estimate of the radius of the ring as a function of amplitude.

  2. Oscillating pendulum decay by emission of vortex rings

    NASA Astrophysics Data System (ADS)

    Bolster, Diogo; Hershberger, Robert E.; Donnelly, Russell J.

    2010-04-01

    We have studied oscillation of a pendulum in water using spherical bobs. By measuring the loss in potential energy, we estimate the drag coefficient on the sphere and compare to data from liquid-helium experiments. The drag coefficients compare very favorably illustrating the true scaling behavior of this phenomenon. We also studied the decay of amplitude of the pendulum over time. As observed previously, at small amplitudes, the drag on the bob is given by the linear Stokes drag and the decay is exponential. For larger amplitudes, the pendulum bob sheds vortex rings as it reverses direction. The momentum imparted to these vortex rings results in an additional discrete drag on the bob. We present experiments and a theoretical estimate of this vortex-ring-induced drag. We analytically derive an estimate for a critical amplitude beyond which vortex ring shedding will occur as well as an estimate of the radius of the ring as a function of amplitude.

  3. O-Ring-Testing Fixture

    NASA Technical Reports Server (NTRS)

    Turner, James E.; Mccluney, D. Scott

    1990-01-01

    Fixture used to evalute properties of O-rings of various materials. Hydraulic actuator positions plug in housing, creating controlled, variable gap in O-ring glands formed by grooves in plug and by inner wall of housing. Creates controlled axial and radial gaps between sealing surfaces around ring so effectiveness of material in maintaining seal determined under dynamic conditions.

  4. RINGED ACCRETION DISKS: EQUILIBRIUM CONFIGURATIONS

    SciTech Connect

    Pugliese, D.; Stuchlík, Z. E-mail: zdenek.stuchlik@physics.cz

    2015-12-15

    We investigate a model of a ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the general relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can then be determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We present also a perturbation analysis based on evolution of the oscillating components of the ringed disk. The dynamics of the unstable phases of the ringed disk evolution seems to be promising in relation to high-energy phenomena demonstrated in active galactic nuclei.

  5. Vortex Rings in Superfluid Helium

    NASA Astrophysics Data System (ADS)

    Alamri, Sultan Z.; Barenghi, Carlo F.

    2008-11-01

    We present results of numerical simulations of large-scale vortex rings in superfluid helium. These large-scale vortex rings consists of many discrete (quantized) vortex filaments which interact with each other moving according to the Biot-Savart law. Lifetime, structural stability and speed of large-scale vortex rings will be discussed and compared to experimental results.

  6. Uranus: the rings are black.

    PubMed

    Sinton, W M

    1977-11-01

    An upper limit of 0.05 is established for the geometric albedo of the newly discovered rings of Uranus. In view of this very low albedo, the particles of the rings cannot be ice-covered as are those of rings A and B of Saturn.

  7. Satellite Rings Movie

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This brief movie clip (of which the release image is a still frame), taken by NASA's Cassini spacecraft as it approached Jupiter, shows the motions, over a 16 hour-period, of two satellites embedded in Jupiter's ring. The moon Adrastea is the fainter of the two, and Metis the brighter. Images such as these will be used to refine the orbits of the two bodies.

    The movie was made from images taken during a 40-hour sequence of the Jovian ring on December 11, 2000.

    Cassini is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages Cassini for NASA's Office of Space Science, Washington, D.C.

  8. Oligomeric ferrocene rings.

    PubMed

    Inkpen, Michael S; Scheerer, Stefan; Linseis, Michael; White, Andrew J P; Winter, Rainer F; Albrecht, Tim; Long, Nicholas J

    2016-09-01

    Cyclic oligomers comprising strongly interacting redox-active monomer units represent an unknown, yet highly desirable class of nanoscale materials. Here we describe the synthesis and properties of the first family of molecules belonging to this compound category-differently sized rings comprising only 1,1'-disubstituted ferrocene units (cyclo[n], n = 5-7, 9). Due to the close proximity and connectivity of centres (covalent Cp-Cp linkages; Cp = cyclopentadienyl) solution voltammograms exhibit well-resolved, separated 1e(-) waves. Theoretical interrogations into correlations based on ring size and charge state are facilitated using values of the equilibrium potentials of these transitions, as well as their relative spacing. As the interaction free energies between the redox centres scale linearly with overall ring charge and in conjunction with fast intramolecular electron transfer (∼10(7) s(-1)), these molecules can be considered as uniformly charged nanorings (diameter ∼1-2 nm). PMID:27554408

  9. Which Ringed Planet...!?

    NASA Astrophysics Data System (ADS)

    2002-12-01

    Don't worry - you are not the only one who thought this was a nice amateur photo of planet Saturn, Lord of the Rings in our Solar System! But then the relative brightness and positions of the moons may appear somewhat unfamiliar... and the ring system does look unusually bright when compared to the planetary disk...?? Well, it is not Saturn, but Uranus , the next giant planet further out, located at a distance of about 3,000 million km, or 20 times the distance between the Sun and the Earth. The photo shows Uranus surrounded by its rings and some of the moons, as they appear on a near-infrared image that was obtained in the K s -band (at wavelength 2.2 µm) with the ISAAC multi-mode instrument on the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory (Chile) . The exposure was made on November 19, 2002 (03:00 hrs UT) during a planetary research programme. The observing conditions were excellent (seeing 0.5 arcsec) and the exposure lasted 5 min. The angular diameter of Uranus is about 3.5 arcsec. The observers at ISAAC were Emmanuel Lellouch and Thérése Encrenaz of the Observatoire de Paris (France) and Jean-Gabriel Cuby and Andreas Jaunsen (both ESO-Chile). The rings The rings of Uranus were discovered in 1977, from observations during a stellar occultation event by astronomer teams at the Kuiper Airborne Observatory (KAO) and the Perth Observatory (Australia). Just before and after the planet moved in front of the (occulted) star, the surrounding rings caused the starlight to dim for short intervals of time. Photos obtained from the Voyager-2 spacecraft in 1986 showed a multitude of very tenuous rings. These rings are almost undetectable from the Earth in visible light. However, on the present VLT near-infrared picture, the contrast between the rings and the planet is strongly enhanced. At the particular wavelength at which this observation was made, the infalling sunlight is almost completely absorbed by gaseous methane present in the planetary atmosphere

  10. Video-Assisted Thoracoscopic Division of Vascular Rings

    PubMed Central

    Lee, Jung Hee; Yang, Ji-Hyuk; Jun, Tae-Gook

    2015-01-01

    This study reports our early experience with thoracoscopic division of vascular rings. Three patients were reviewed; their ages at surgery were 25 months, 4 years, and 57 years. All patients were suffering from complete vascular rings involving combinations of the right aortic arch, left ligamentum arteriosum, Kommerell’s diverticulum, and retroesophageal left subclavian artery. The median surgical time was 180.5 minutes, and the patients showed immediate recovery. Three complications, namely chylothorax, transient supraventricular tachycardia, and left vocal cord palsy, were observed. Our early experience indicates that thoracoscopic division of a vascular ring may provide early recovery and could be a promising operative choice. PMID:25705605

  11. Uranus rings and two moons

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Voyager 2 has discovered two 'shepherd' satellites associated with the rings of Uranus. The two moons -- designated 1986U7 and 1986U8 -- are seen here on either side of the bright epsilon ring; all nine of the known Uranian rings are visible. The image was taken Jan. 21, 1986, at a distance of 4.1 million kilometers (2.5 million miles) and resolution of about 36 km (22 mi). The image was processed to enhance narrow features. The epsilon ring appears surrounded by a dark halo as a result of this processing; occasional blips seen on the ring are also artifacts. Lying inward from the epsilon ring are the delta, gamma and eta rings; then the beta and alpha rings; and finally the barely visible 4, 5 and 6 rings. The rings have been studied since their discovery in 1977, through observations of how they diminish the light of stars they pass in front of. This image is the first direct observation of all nine rings in reflected sunlight. They range in width from about 100 km (60 mi) at the widest part of the epsilon ring to only a few kilometers for most of the others. The discovery of the two ring moons 1986U7 and 1986U8 is a major advance in our understanding of the structure of the Uranian rings and is in good agreement with theoretical predictions of how these narrow rings are kept from spreading out. Based on likely surface brightness properties, the moons are of roughly 2O- and 3O-km diameter, respectively. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

  12. 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.

  13. Dynamics of non Newtonian vortex rings

    NASA Astrophysics Data System (ADS)

    Palacios-Morales, C. A.; Barbosa, C.; Zenit, R.

    2012-11-01

    The dynamics of formation and evolution of non-Newtonian vortex rings generated in a piston-cylinder arrangement are studied. The ratio of the piston displacement Lm to the internal cylinder diameter D0, the piston velocity Up and fluid properties determine the vortex properties and evolution. Measurements of the 2D velocity field were obtained with a PIV technique. The vortex circulation Γ was computed considering a vortex identification scheme (Q criterion). Experiments with fluids with different rheological properties (shear thinning and viscoelastic) are presented. Our Newtonian experiments agree with previous investigations. For shear-thinning liquids, we observed that the final vortex circulation decreases with the fluid power index, n. We show that the total circulation ejected from the cylinder is reduced when the thinning property of the liquid increases; thus, the circulation confined inside the vortex ring, is reduced too. For vortex rings in a viscoelastic liquid, the formation of a `negative wake' (returning flow) and a second vortex ring with opposite whirl are observed. We show that the negative wake results from the high extension rates produced during the vortex formation.

  14. Ideals of generalized matrix rings

    SciTech Connect

    Budanov, Aleksandr V

    2011-01-31

    Let R and S be rings, and {sub R}M{sub S} and {sub S}N{sub R} bimodules. In the paper, in terms of isomorphisms of lattices, relationships between the lattices of one-sided and two-sided ideals of the generalized matrix ring and the corresponding lattices of ideals of the rings R and S are described. Necessary and sufficient conditions for a pair of ideals I, J of rings R and S, respectively, to be the main diagonal of some ideal of the ring K are also obtained. Bibliography: 8 titles.

  15. O-Ring-Testing Fixture

    NASA Technical Reports Server (NTRS)

    Turner, James E.; Mccluney, D. Scott

    1991-01-01

    Fixture tests O-rings for sealing ability under dynamic conditions after extended periods of compression. Hydraulic cylinder moves plug in housing. Taper of 15 degrees on plug and cavity of housing ensures that gap created between O-ring under test and wall of cavity. Secondary O-rings above and below test ring maintain pressure applied to test ring. Evaluates effects of variety of parameters, including temperature, pressure, rate of pressurization, rate and magnitude of radial gap movement, and pretest compression time.

  16. New instability of Saturn's ring

    SciTech Connect

    Goertz, C.K.; Morfill, G.

    1988-05-01

    Perturbations in the Saturn ring's mass density are noted to be prone to instabilities through the sporadic elevation of submicron-size dust particles above the rings, which furnishes an effective angular momentum exchange between the rings and Saturn. The dust thus elevated from the ring settles back onto it at a different radial distance. The range of wavelength instability is determinable in light of the dust charge, the average radial displacement of the dust, and the fluctuation of these quantities. It is suggested that at least some of the B-ring's ringlets may arise from the instability.

  17. Helmet latching and attaching ring

    NASA Technical Reports Server (NTRS)

    Chase, E. W.; Viikinsalo, S. J. (Inventor)

    1970-01-01

    A neck ring releasably secured to a pressurized garment carries an open-ended ring normally in the engagement position fitted into an annular groove and adapted to fit into a complementary annular groove formed in a helmet. Camming means formed on the inner surface at the end of the helmet engages the open-ended ring to retract the same and allow for one motion donning even when the garment is pressurized. A projection on the end of the split ring is engageable to physically retract the split ring.

  18. Experimental observation of the collision of three vortex rings

    NASA Astrophysics Data System (ADS)

    Hernández, R. H.; Monsalve, E.

    2015-06-01

    We investigate for the first time the motion, interaction and simultaneous collision between three initially stable vortex rings arranged symmetrically, making an angle of 120 degrees between their straight path lines. We report results with laminar vortex rings in air and water obtained through measurements of the ring velocity field with a hot-wire anemometer, both in free flight and during the entire collision. In the air experiment, our flow visualizations allowed us to identify two main collision stages. A first ring-dominated stage where the rings slowdown progressively, increasing their diameter rapidly, followed by secondary vortex structures resulting after the rings make contact. Local portions of the vortex tubes of opposite circulation are coupled together thus creating local arm-like vortex structures moving radially in outward directions, rapidly dissipating kinetic energy. From a similar water experiment, we provide detailed shadowgraph visualizations of both the ring bubble and the full size collision, showing clearly the final expanding vortex structure. It is accurately resolved that the physical contact between vortex ring tubes gives rise to three symmetric expanding vortex arms but also the vortex reconnection of the top and lower vortex tubes. The central collision zone was found to have the lowest kinetic energy during the entire collision and therefore it can be identified as a safe zone. The preserved collision symmetries leading to the weak kinematic activity in the safe zone is the first step into the development of an intermittent hydrodynamic trap for small and lightweight particles.

  19. Continuous ring furnaces

    SciTech Connect

    De Stefani, G.; Genevois, J.L.; Paolo, P.

    1981-01-06

    A smoke conducting apparatus for use particularly with continuous ring furnaces (e.g., Hoffman furnaces) wherein each furnace chamber is connected to the smoke channel, the latter being a metal pipe inclined slightly from horizontal and provided with one or more traps along the length of its bottom surface, each trap containing a removable receptacle, and heating means being disposed along the bottom of the channel to fluidize tarry deposits of combustion products so that such deposits will flow by gravity into the removable receptacle.

  20. Two rings too tight: sequential emergency PCI for hemodynamic and arrhythmic complications of mitral and tricuspid valve repair.

    PubMed

    Patel, Niket; Cuculi, Florim; Banning, Adrian P

    2014-01-01

    New intra-operative mitral regurgitation is an unusual complication of tricuspid annuloplasty and maybe ischemic in etiology as a consequence of right coronary artery distortion. We report the case of a woman in whom this was treated by mitral valve annuloplasty with ensuing hemodynamic instability and ventricular arrhythmia secondary to a new left circumflex occlusion. Injury/distortion to either of the coronary arteries running in the atrio-ventricular groove is rare, and described only several times. To our knowledge, concurrent right coronary artery and circumflex artery injury/distortion has not been reported previously.

  1. Planetary Rings: Statistical Description of Fragmentation of Ring-agglomerates

    NASA Astrophysics Data System (ADS)

    Spahn, Frank; Vieira Neto, E.; Guimaraes, A. H. F.; Brilliantov, N. V.; Gorban, A. N.

    2009-09-01

    We study the fragmentation dynamics of a two-dimensional agglomerate, hold together by adhesive bonds, caused by an impacting projectile of given mass and impact speed/energy. The agglomerate is made of identical adhering spheres (constituents) forming a regular cubic lattice. A rather simple "random walk model" of a crack propagation has been studied numerically and analytically, where subsequent breaking of adhesive bonds (defining the crack path) is organized randomly and the breakage continues until the impact energy of the projectile is exhausted. A large number of repeated numerical breakage experiments have yielded a surprising agreement with egg-shell crushing experiments (Hermann et al., Physica A 371 (2006), 59) - i.e. the size distribution of the fragments obeys a power law, p(s) sa with a = -3/2. This distribution can theoretically described by a one-dimensional random walk model to mimick the propagation of the crack. With this prerequisite the fragment sizes can be mapped to the mean time of two distant cracks to meet (mean free passage time) in this way justifying the above distribution. These studies will serve as an input for a kinetic description (Spahn et al. 2004, Europhys. Lett. 67 (2004), 545) of a balance between coagulation and fragmentation to describe the "meso-scopic" dynamics of dense planetary rings.

  2. Saturn ring temperature variations with approaching ring equinox

    NASA Astrophysics Data System (ADS)

    Spilker, L.; Leyrat, C.; Flandes, A.; Altobelli, N.; Pilorz, S.; Ferrari, C.; Edgington, S.

    2009-04-01

    Cassini's Composite Infrared Spectrometer (CIRS) has acquired a wide-ranging set of thermal measurements of Saturn's main rings (A, B, C and Cassini Division) at solar elevations ranging from less than one degree to 24 degrees. At Saturn equinox in August the solar elevation angle will reach zero as the sun traverses from the south to north side of the rings. For the data acquired to date, temperatures were retrieved for the lit and unlit rings over a variety of ring geometries that include solar elevation, as well as spacecraft elevation, phase angle and local hour angle. To first order, the largest temperature changes on the lit face of the rings are driven by variations in phase angle while differences in temperature with changing spacecraft elevation and local time are a secondary effect. Decreasing ring temperature with decreasing solar elevation are observed for both the lit and unlit faces of the rings after phase angle and local time effects are taken into account. As the solar elevation continues to decrease, the ring temperatures are decreasing in a non-linear fashion. The difference in temperature between the lit and unlit sides of the rings is decreasing also with decreasing solar elevation. Using ring thermal models developed by Leyrat we extrapolate to the expected minimum ring temperatures at equinox for our planned CIRS ring observations. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA and at CEA Saclay supported by the "Programme National de Planetologie". Copyright 2009 California Institute of Technology. Government sponsorship acknowledged.

  3. Powder-lubricated piston ring development. Final report

    SciTech Connect

    Heshmat, H.

    1991-06-01

    The overall objective of this program was to demonstrate the feasibility of a new particulate lubrication concept for reducing piston ring/cylinder liner wear in coal-water slurry-fueled diesels by replacing the present oil-lubricated system with powder lubrication that would utilize coal ash, either alone or in combination with another powder. The feasibility of this particular lubrication concept for reducing ring/liner wear was demonstrated in a series of experiments utilizing redesigned and properly selected components. Wear performance for suitable ring/liner materials lubricated with a powder that incorporates the abrasive ash particles was evaluated in terms of load capacity, friction, and rate of wear for the best combination of ring design, ring and liner materials, and powder constituents. In addition, the use of a powder-lubricated system in the upper portion of the cylinder isolated the particulates from the lower portions of the engine, thus further reducing engine wear. (VC)

  4. Kinematics and dynamics of vortex rings in a tube

    NASA Technical Reports Server (NTRS)

    Brasseur, J. G.

    1979-01-01

    Kinematic theory and flow visualization experiments were combined to examine the dynamic processes which control the evolution of vortex rings from very low to very high Reynolds numbers, and to assess the effects of the wall as a vortex ring travels up a tube. The kinematic relationships among the size, shape, speed, and strength of vortex rings in a tube were computed from the theory. Relatively simple flow visualization measurements were used to calculate the total circulation of a vortex rings at a given time. Using this method, the strength was computated and plotted as a function of time for experimentally produced vortex rings. Reynolds number relationships are established and quantitative differences among the three Reynolds number groups are discussed.

  5. Where are the spokes in Saturn's B ring?

    NASA Astrophysics Data System (ADS)

    Mitchell, C. J.; Mihaly Horanyi, M.

    2005-08-01

    The spokes in Saturn's B ring are radial features which appear dark in backscattered light but bright in forward scattered light, indicating that they are composed of small dust particles. First observed by the Voyager imaging experiment, they were also observed during the last ring plane crossing by McGhee et al. (2005) using the Hubble Space Telescope, but they have yet to be observed by Cassini. In order to explain the lack of spokes, we expand on the work of Nitter et al. (1998) where the plasma environment and electric field immediately above the ring affects the motion of the spoke particles due to their charge. As the charging conditions change due to variations in the ambient plasma environment and the solar elevation angle, spoke particles which would survive above the ring for several hours during the Voyager flybys are very rapidly pulled back down onto the ring under the current conditions, preventing spoke formation.

  6. Ring Image Analyzer

    NASA Technical Reports Server (NTRS)

    Strekalov, Dmitry V.

    2012-01-01

    Ring Image Analyzer software analyzes images to recognize elliptical patterns. It determines the ellipse parameters (axes ratio, centroid coordinate, tilt angle). The program attempts to recognize elliptical fringes (e.g., Newton Rings) on a photograph and determine their centroid position, the short-to-long-axis ratio, and the angle of rotation of the long axis relative to the horizontal direction on the photograph. These capabilities are important in interferometric imaging and control of surfaces. In particular, this program has been developed and applied for determining the rim shape of precision-machined optical whispering gallery mode resonators. The program relies on a unique image recognition algorithm aimed at recognizing elliptical shapes, but can be easily adapted to other geometric shapes. It is robust against non-elliptical details of the image and against noise. Interferometric analysis of precision-machined surfaces remains an important technological instrument in hardware development and quality analysis. This software automates and increases the accuracy of this technique. The software has been developed for the needs of an R&TD-funded project and has become an important asset for the future research proposal to NASA as well as other agencies.

  7. Experimental results from the small isochronous ring

    SciTech Connect

    Eduard Pozdeyev

    2005-05-01

    The Small Isochronous Ring (SIR) is a compact, low-energy storage ring designed to investigate the beam dynamics of high-intensity isochronous cyclotrons and synchrotrons at the transition energy. The ring was developed at Michigan State University (MSU) and has been operational since December 2003. It stores 20 keV hydrogen beams with a peak current of 10-20 microamps for up to 200 turns. The transverse and longitudinal profiles of extracted bunches are measured with an accuracy of approximately 1 mm. The high accuracy of the measurements makes the experimental data attractive for validation of multi-particle space charge codes. The results obtained in the ring show a fast growth of the energy spread induced by the space charge forces. The energy spread growth is accompanied by a breakup of the beam bunches into separated clusters that are involved in the vortex motion specific to the isochronous regime. The experimental results presented in the paper show a remarkable agreement with simulations performed with the code CYCO. In this paper, we discuss specifics of space charge effects in the isochronous regime, present results of experiments in SIR, and conduct a detailed comparison of the experimental data with results of simulations.

  8. Intraocular Radio-Opaque Ring.

    PubMed

    Shieh, Christine; Folz, Emily; Fekrat, Sharon

    2015-01-01

    A radiologist noted a radio-opaque object in the eye of a woman undergoing X-ray examination to determine the safety of magnetic resonance imaging (MRI). Water's X-ray shows the titanium locking c-ring of a type 1 Boston keratoprosthesis. This ring was added in 2004 to prevent intraocular disassembly of the device. The nonmagnetic ring does not prevent MRI imaging. The titanium locking c-ring and the titanium or polymethyl methacrylate back plate of the Boston keratoprosthesis are safe for MRI imaging. PMID:26271082

  9. Saturn's Rings Edge-on

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In one of nature's most dramatic examples of 'now-you see-them, now-you-don't', NASA's Hubble Space Telescope captured Saturn on May 22, 1995 as the planet's magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn's ring plane.

    For comparison, the top picture was taken by Hubble on December 1, 1994 and shows the rings in a more familiar configuration for Earth observers.

    The bottom picture was taken shortly before the ring plane crossing. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn's atmosphere. Two of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are, from left to right, Tethys (slightly above the ring plane) and Dione.

    This observation will be used to determine the time of ring-plane crossing and the thickness of the main rings and to search for as yet undiscovered satellites. Knowledge of the exact time of ring-plane crossing will lead to an improved determination of the rate at which Saturn 'wobbles' about its axis (polar precession).

    Both pictures were taken with Hubble's Wide Field Planetary Camera 2. The top image was taken in visible light. Saturn's disk appears different in the bottom image because a narrowband filter (which only lets through light that is not absorbed by methane gas in Saturn's atmosphere) was used to reduce the bright glare of the planet. Though Saturn is approximately 900 million miles away, Hubble can see details as small as 450 miles across.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science

  10. Split ring containment attachment device

    DOEpatents

    Sammel, Alfred G.

    1996-01-01

    A containment attachment device 10 for operatively connecting a glovebag 200 to plastic sheeting 100 covering hazardous material. The device 10 includes an inner split ring member 20 connected on one end 22 to a middle ring member 30 wherein the free end 21 of the split ring member 20 is inserted through a slit 101 in the plastic sheeting 100 to captively engage a generally circular portion of the plastic sheeting 100. A collar potion 41 having an outer ring portion 42 is provided with fastening means 51 for securing the device 10 together wherein the glovebag 200 is operatively connected to the collar portion 41.

  11. Statistical ring current of Saturn

    NASA Astrophysics Data System (ADS)

    Carbary, J. F.; Achilleos, N.; Arridge, C. S.

    2012-06-01

    The statistical ring current of Saturn has been determined from the curl of the median magnetic field derived from over 5 years of observations of the Cassini magnetometer. The main issue addressed here is the calculation of the statistical ring current of Saturn by directly computing, for the first time, the symmetrical part of the ring current J from the Maxwell equation ∇ × B = μ0J from assembling the perturbation magnetic field B from 2004 through 2010. This study validates previous studies, based on fewer data and not using ∇ × B, and shows that the ring current flows eastward (in the +ϕ or corotation direction) and extends from ˜3 RS to at least ˜20 RS (1 RS = 60,268 km), which is the vicinity of the dayside magnetopause; that the ring current has a peak strength of ˜75 pA/m2 at ˜9.5 RS; and that the ring current has a half-width of ˜1.5 RS. Two outcomes of this study are that the ring current bends northward, as suggested by the “bowl” model of Saturn's plasma sheet, and that the total ring current is 9.2 ± 1.0 MA. In the context of future endeavors, the statistical ring current presented here can be used for calculations of the magnetic field of Saturn for particle drifts, field line mapping, and J × B force.

  12. Formation of lunar basin rings

    USGS Publications Warehouse

    Hodges, C.A.; Wilhelms, D.E.

    1978-01-01

    The origin of the multiple concentric rings that characterize lunar impact basins, and the probable depth and diameter of the transient crater have been widely debated. As an alternative to prevailing "megaterrace" hypotheses, we propose that the outer scarps or mountain rings that delineate the topographic rims of basins-the Cordilleran at Orientale, the Apennine at Imbrium, and the Altai at Nectaris-define the transient cavities, enlarged relatively little by slumping, and thus are analogous to the rim crests of craters like Copernicus; inner rings are uplifted rims of craters nested within the transient cavity. The magnitude of slumping that occurs on all scarps is insufficient to produce major inner rings from the outer. These conclusions are based largely on the observed gradational sequence in lunar central uplifts:. from simple peaks through somewhat annular clusters of peaks, peak and ring combinations and double ring basins, culminating in multiring structures that may also include peaks. In contrast, belts of slump terraces are not gradational with inner rings. Terrestrial analogs suggest two possible mechanisms for producing rings. In some cases, peaks may expand into rings as material is ejected from their cores, as apparently occurred at Gosses Bluff, Australia. A second process, differential excavation of lithologically diverse layers, has produced nested experimental craters and is, we suspect, instrumental in the formation of terrestrial ringed impact craters. Peak expansion could produce double-ring structures in homogeneous materials, but differential excavation is probably required to produce multiring and peak-in-ring configurations in large lunar impact structures. Our interpretation of the representative lunar multiring basin Orientale is consistent with formation of three rings in three layers detected seismically in part of the Moon-the Cordillera (basin-bounding) ring in the upper crust, the composite Montes Rook ring in the underlying

  13. Structural basis for role of ring finger protein RNF168 RING domain

    PubMed Central

    Zhang, Xiaoqin; Chen, Jie; Wu, Minhao; Wu, Huakai; Arokiaraj, Aloysius Wilfred; Wang, Chengliang; Zhang, Weichang; Tao, Yue; Huen, Michael S.Y.; Zang, Jianye

    2013-01-01

    Ubiquitin adducts surrounding DNA double-strand breaks (DSBs) have emerged as molecular platforms important for the assembly of DNA damage mediator and repair proteins. Central to these chromatin modifications lies the E2 UBC13, which has been implicated in a bipartite role in priming and amplifying lys63-linked ubiquitin chains on histone molecules through coupling with the E3 RNF8 and RNF168. However, unlike the RNF8-UBC13 holoenyzme, exactly how RNF168 work in concert with UBC13 remains obscure. To provide a structural perspective for the RNF168-UBC13 complex, we solved the crystal structure of the RNF168 RING domain. Interestingly, while the RNF168 RING adopts a typical RING finger fold with two zinc ions coordinated by several conserved cystine and histine residues arranged in a C3HC4 “cross-brace” manner, structural superimposition of RNF168 RING with other UBC13-binding E3 ubiquitin ligases revealed substantial differences at its corresponding UBC13-binding interface. Consistently, and in stark contrast to that between RNF8 and UBC13, RNF168 did not stably associate with UBC13 in vitro or in vivo. Moreover, domain-swapping experiments indicated that the RNF8 and RNF168 RING domains are not functionally interchangeable. We propose that RNF8 and RNF168 operate in different modes with their cognate E2 UBC13 at DSBs. PMID:23255131

  14. Effect of a ground plane on a turbulent vortex ring trajectory

    NASA Astrophysics Data System (ADS)

    Beninati, Maria-Laura; McErlean, Michael; Krane, Michael; Fontaine, Arnold

    2010-11-01

    Experiments were conducted to assess how a turbulent (Re=20000) vortex ring's trajectory is affected by a ground plane parallel to its initial trajectory. This study, part of a larger effort in vortex-particle interaction, aims to characterize the vortex ring flow disturbance that interacts with a particle. Vortex ring motion was characterized for four distances between the initial vortex ring axis and the ground plane. Characterization included vortex centroid motion and diameter from high-speed video, vortex ring circulation from DPIV, and the wall pressure disturbance time traces. It was observed that in all cases the vortex ring trajectory is deflected toward the plane, ending in a collision. As plate height is decreased, the collision occurs closer to the ring generator, the wall pressure signature is also more intense, and the symmetry of the ring is affected more strongly.

  15. Origin of outer rings in lunar multi-ringed basins - Evidence from morphology and ring spacing

    NASA Technical Reports Server (NTRS)

    Head, J. W.

    1977-01-01

    The reported investigation has the objective to examine both the morphology and morphometry of several of the freshest lunar basins including Orientale, Imbrium, Nectaris, Crisium, and Humorum, and to compare the characteristics of their three most prominent rings to features in smaller craters. On the basis of comparisons it is concluded that the outer basin ring forms within the region where significant structural uplift of the basin rim is to be expected. Therefore the formation of the outer ring scarp may be closely associated with structural uplift of the inner portion of the crater rim flank. According to a model suggested for the origin of the outer two rings, the cratering event formed two inner rings, a central peak ring, and an uplifted crater rim crest, with deposition of ejecta during the process.

  16. Status of the Frankfurt low energy electrostatic storage ring (FLSR)

    NASA Astrophysics Data System (ADS)

    King, F.; Kruppi, T.; Müller, J.; Dörner, R.; Schmidt, L. Ph H.; Schmidt-Böcking, H.; Stiebing, K. E.

    2015-11-01

    Frankfurt low-energy storage ring (FLSR) is an electrostatic storage ring for low-energy ions up to q · 80 keV (q being the ion charge state) at Institut für Kernphysik der Goethe-Universität, Frankfurt am Main, Germany. It has especially been designed to provide a basis for experiments on the dynamics of ionic and molecular collisions in complete kinematics, as well as for high precision and time resolved laser spectroscopy. The ring has ‘racetrack’ geometry with a circumference of 14.23 m. It comprises four experimental/diagnostic sections with regions of enhanced ion density (interaction regions). First beam has successfully been stored in FLSR in summer 2013. Since then the performance of the ring has continuously been improved and an electron target for experiments on dissociative recombination has been installed in one of the experimental sections.

  17. Black ring deconstruction

    SciTech Connect

    Gimon, Eric; Gimon, Eric G.; Levi, Thomas S.

    2007-06-22

    We present a sample microstate for a black ring in four and five dimensional language. The microstate consists of a black string microstate with an additional D6-brane. We show that with an appropriate choice of parameters the piece involving the black string microstate falls down a long AdS throat, whose M-theory lift is AdS_3 x S2. We wrap a spinning dipole M2-brane on the S2 in the probe approximation. In IIA, this corresponds to a dielectric D2-brane carrying only D0-charge. We conjecture this is the firstapproximation to a cloud of D0-branes blowing up due to their non-abelian degrees of freedom and the Myers effect.

  18. The Saturn Ring Observer: In situ studies of planetary rings

    NASA Astrophysics Data System (ADS)

    Nicholson, P. D.; Tiscareno, M. S.; Spilker, L. J.

    2010-12-01

    As part of the Planetary Science Decadal Survey recently undertaken by the NRC's Space Studies Board for the National Academy of Sciences, studies were commissioned for a number of potential missions to outer planet targets. One of these studies examined the technological feasibility of a mission to carry out in situ studies of Saturn's rings, from a spacecraft placed in a circular orbit above the ring plane: the Saturn Ring Observer. The technical findings and background are discussed in a companion poster by T. R. Spilker et al. Here we outline the science goals of such a mission. Most of the fundamental interactions in planetary rings occur on spatial scales that are unresolved by flyby or orbiter spacecraft. Typical particle sizes in the rings of Saturn are in the 1 cm - 10 m range, and average interparticle spacings are a few meters. Indirect evidence indicates that the vertical thickness of the rings is as little as 5 - 10 m, which implies a velocity dispersion of only a few mm/sec. Theories of ring structure and evolution depend on the unknown characteristics of interparticle collisions and on the size distribution of the ring particles. The SRO could provide direct measurements of both the coefficient of restitution -- by monitoring individual collisions -- and the particles’ velocity dispersion. High-resolution observations of individual ring particles should also permit estimates of their spin states. Numerical simulations of Saturn’s rings incorporating both collisions and self-gravity predict that the ring particles are not uniformly distributed, but are instead clustered into elongated structures referred to as “self-gravity wakes”, which are continually created and destroyed on an orbital timescale. Theory indicates that the average separation between wakes in the A ring is of order 30-100 m. Direct imaging of self-gravity wakes, including their formation and subsequent dissolution, would provide critical validation of these models. Other

  19. Magnetic fields in ring galaxies

    NASA Astrophysics Data System (ADS)

    Moss, D.; Mikhailov, E.; Silchenko, O.; Sokoloff, D.; Horellou, C.; Beck, R.

    2016-07-01

    Context. Many galaxies contain magnetic fields supported by galactic dynamo action. The investigation of these magnetic fields can be helpful for understanding galactic evolution; however, nothing definitive is known about magnetic fields in ring galaxies. Aims: Here we investigate large-scale magnetic fields in a previously unexplored context, namely ring galaxies, and concentrate our efforts on the structures that appear most promising for galactic dynamo action, i.e. outer star-forming rings in visually unbarred galaxies. Methods: We use tested methods for modelling α-Ω galactic dynamos, taking into account the available observational information concerning ionized interstellar matter in ring galaxies. Results: Our main result is that dynamo drivers in ring galaxies are strong enough to excite large-scale magnetic fields in the ring galaxies studied. The variety of dynamo driven magnetic configurations in ring galaxies obtained in our modelling is much richer than that found in classical spiral galaxies. In particular, various long-lived transients are possible. An especially interesting case is that of NGC 4513, where the ring counter-rotates with respect to the disc. Strong shear in the region between the disc and the ring is associated with unusually strong dynamo drivers in such counter-rotators. The effect of the strong drivers is found to be unexpectedly moderate. With counter-rotation in the disc, a generic model shows that a steady mixed parity magnetic configuration that is unknown for classical spiral galaxies, may be excited, although we do not specifically model NGC 4513. Conclusions: We deduce that ring galaxies constitute a morphological class of galaxies in which identification of large-scale magnetic fields from observations of polarized radio emission, as well as dynamo modelling, may be possible. Such studies have the potential to throw additional light on the physical nature of rings, their lifetimes, and evolution.

  20. Biomechanics of Corneal Ring Implants

    PubMed Central

    2015-01-01

    Purpose: To evaluate the biomechanics of corneal ring implants by providing a related mathematical theory and biomechanical model for the treatment of myopia and keratoconus. Methods: The spherical dome model considers the inhomogeneity of the tunica of the eye, dimensions of the cornea, lamellar structure of the corneal stroma, and asphericity of the cornea. It is used in this study for calculating a strengthening factor sf for the characterization of different ring-shaped corneal implant designs. The strengthening factor is a measure of the amount of strengthening of the cornea induced by the implant. Results: For ring segments and incomplete rings, sf = 1.0, which indicates that these implants are not able to strengthen the cornea. The intracorneal continuous complete ring (MyoRing) has a strengthening factor of up to sf = 3.2. The MyoRing is, therefore, able to strengthen the cornea significantly. Conclusions: The result of the presented biomechanical analysis of different ring-shaped corneal implant designs can explain the different postoperative clinical results of different implant types in myopia and keratoconus. PMID:26312619

  1. Running Rings Around the Web.

    ERIC Educational Resources Information Center

    McDermott, Irene E.

    1999-01-01

    Describes the development and current status of WebRing, a service that links related Web sites into a central hub. Discusses it as a viable alternative to other search engines and examines issues of free speech, use by the business sector, and implications for WebRing after its purchase by Yahoo! (LRW)

  2. How Jupiter's Ring Was Discovered.

    ERIC Educational Resources Information Center

    Elliot, James; Kerr, Richard

    1985-01-01

    "Rings" (by astronomer James Elliot and science writer Richard Kerr) is a nontechnical book about the discovery and exploration of ring systems from the time of Galileo to the era of the Voyager spacecraft. One of this book's chapters is presented. (JN)

  3. Fibre ring cavity semiconductor laser

    SciTech Connect

    Duraev, V P; Medvedev, S V

    2013-10-31

    This paper presents a study of semiconductor lasers having a polarisation maintaining fibre ring cavity. We examine the operating principle and report main characteristics of a semiconductor ring laser, in particular in single- and multiple-frequency regimes, and discuss its application areas. (lasers)

  4. The rare-RI ring

    NASA Astrophysics Data System (ADS)

    Ozawa, A.; Uesaka, T.; Wakasugi, M.; Rare-RI Ring Collaboration

    2012-12-01

    We describe the rare-RI (radioactive isotope) ring at the RI Beam Factory (RIBF). The main purpose of the rare-RI ring is to measure the mass of very neutron-rich nuclei, the production rates of which are very small (hence ‘rare RI’) and the lifetimes of which are predicted to be very short. In the rare-RI ring, there are two innovative pieces of apparatus: individual injection, which can realize the injection of 200 A MeV rare RIs one by one, and a cyclotron-like storage ring, which allows high isochronous magnetic fields with large angular and momentum acceptances. With these devices, we will achieve a 10-6 mass resolution, and will be able to access rare RIs, the production rate of which is down to 1 event/day/pnA. Construction of the rare-RI ring started in fiscal year 2012.

  5. 21 CFR 880.6200 - Ring cutter.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ring cutter. 880.6200 Section 880.6200 Food and....6200 Ring cutter. (a) Identification. A ring cutter is a device intended for medical purposes that is used to cut a ring on a patient's finger so that the ring can be removed. The device incorporates...

  6. 21 CFR 880.6200 - Ring cutter.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ring cutter. 880.6200 Section 880.6200 Food and....6200 Ring cutter. (a) Identification. A ring cutter is a device intended for medical purposes that is used to cut a ring on a patient's finger so that the ring can be removed. The device incorporates...

  7. 21 CFR 880.6200 - Ring cutter.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ring cutter. 880.6200 Section 880.6200 Food and....6200 Ring cutter. (a) Identification. A ring cutter is a device intended for medical purposes that is used to cut a ring on a patient's finger so that the ring can be removed. The device incorporates...

  8. 21 CFR 880.6200 - Ring cutter.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ring cutter. 880.6200 Section 880.6200 Food and....6200 Ring cutter. (a) Identification. A ring cutter is a device intended for medical purposes that is used to cut a ring on a patient's finger so that the ring can be removed. The device incorporates...

  9. 21 CFR 880.6200 - Ring cutter.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ring cutter. 880.6200 Section 880.6200 Food and....6200 Ring cutter. (a) Identification. A ring cutter is a device intended for medical purposes that is used to cut a ring on a patient's finger so that the ring can be removed. The device incorporates...

  10. Ring Buffered Network Bus

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This report describes the research effort to demonstrate the integration of a data sharing technology, Ring Buffered Network Bus, in development by Dryden Flight Research Center, with an engine simulation application, the Java Gas Turbine Simulator, in development at the University of Toledo under a grant from the Glenn Research Center. The objective of this task was to examine the application of the RBNB technologies as a key component in the data sharing, health monitoring and system wide modeling elements of the NASA Aviation Safety Program (AVSP) [Golding, 1997]. System-wide monitoring and modeling of aircraft and air safety systems will require access to all data sources which are relative factors when monitoring or modeling the national airspace such as radar, weather, aircraft performance, engine performance, schedule and planning, airport configuration, flight operations, etc. The data sharing portion of the overall AVSP program is responsible for providing the hardware and software architecture to access and distribute data, including real-time flight operations data, among all of the AVSP elements. The integration of an engine code capable of numerically "flying" through recorded flight paths and weather data using a software tool that allows for distributed access of data to this engine code demonstrates initial steps toward building a system capable of monitoring and modeling the National Airspace.

  11. DETECTION OF LOW-VELOCITY COLLISIONS IN SATURN'S F RING

    SciTech Connect

    Attree, N. O.; Murray, C. D.; Cooper, N. J.; Williams, G. A.

    2012-08-20

    Jets of material extending several hundred kilometers from Saturn's F ring are thought to be caused by collisions at speeds of several tens of ms{sup -1} between {approx}10 km diameter objects such as S/2004 S 6 and the core of the ring. The subsequent effects of Keplerian shear give rise to the multi-stranded nature of the F ring. Observations of the ring by the Imaging Science Subsystem experiment on the Cassini spacecraft have provided evidence that some smaller protrusions from the ring's core are the result of low-velocity collisions with nearby objects. We refer to these protrusions as 'mini-jets' and one such feature has been observed for {approx}7.5 hr as its length changed from {approx}75 km to {approx}250 km while it simultaneously appeared to collapse into the core. Orbit determinations suggest that such mini-jets consist of ring material displaced by a {approx}1 ms{sup -1} collision with a nearby moonlet, resulting in paths relative to the core that are due to a combination of Keplerian shear and epicyclic motion. Detections of mini-jets in the Cassini images suggest that it may now be possible to understand most small-scale F ring structure as the result of such collisions. A study of these mini-jets will therefore put constraints on the properties of the colliding population as well as improve our understanding of low-velocity collisions between icy objects.

  12. Particle properties and processes in Uranus' rings

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.; Brahic, A.; Burns, J. A.; Marouf, Essam A.

    1991-01-01

    The particle properties and processes in the Uranian rings are analyzed from Voyager observations and ground-based data. Occultation observations of the epsilon ring are interpreted to yield an effective size of the ring particles that exceeds 70 cm, a surface mass density that exceeds 80 g/sq cm, and a ring vertical thickness greater than tens of meters for solid ice particles. The particles forming the classic rings are dark and gray, with albedo of 0.014 +/-0.004. It is argued that the small amount of dust that exists in the classical rings and between the rings in bands is created by erosion of ring particles and unseen satellites resulting from collisions and micrometeoroid bombardment. As proposed for regions of the other known ring systems, new ring material can be continually created by the destruction of small moons near the rings, which may explain the youthful appearance of the Uranian rings.

  13. Entrainment in interacting vortex rings

    NASA Astrophysics Data System (ADS)

    Shami, Rammah; Ganapathisubramani, Bharathram

    2014-11-01

    The efficiency of entrainment in single vortex rings has been examined by various studies in the literature. These studies have shown that this efficiency is greatly increased for smaller stroke-time to nozzle-diameter ratios, L/D. However, no clear consensus exists regarding the effect on the entrainment process for the sectioned delivery of the vortex forming impulse. In the present work the entrainment mechanism associated with the interaction between two co-axially separated vortex rings is explored. Planar, time-resolved particle image velocimetry (PIV) measurements are taken of a interacting vortex flow field. Lagrangian coherent structures (LCS) extracted from the finite-time Lyapunov exponent (FTLE) fields are employed to determine the vortex boundaries of the interacting rings and is then used to measure entrainment. Preliminary results indicate that whilst the most efficient entrainment of ambient fluid by the ring pairs occurs at larger separations, the rate and overall mass transport increase can be controlled by altering the spatial/temporal separation between successive rings and is higher at smaller ring spacing. Variation in mass transport behaviour for different ring strengths (L/D) and Reynolds numbers will also be discussed.

  14. Modeling piston-ring dynamics, blowby, and ring-twist effects

    SciTech Connect

    Tian, T.; Noordzij, L.B.; Wong, V.W.; Heywood, J.B.

    1996-12-31

    A ring-dynamics and gas-flow model has been developed to study ring/groove contact, blowby, and the influence of ring static twist, keystone ring/groove configurations, and other piston and ring parameters. The model is developed for a ring pack with three rings. The dynamics of the top two rings and the gas pressures in the regions above the oil control ring are simulated. Distributions of oil film thickness and surface roughness on the groove and ring surfaces are assumed in the model to calculate the forces generated by the ring/groove contact. Ring static and dynamic twists are considered as well as different keystone ring/groove configurations. Ring dynamics and gas flows are coupled in the formulation and an implicit scheme is implemented, enabling the model to resolve detailed events such as ring flutter. Studies on a spark ignition engine found that static twist or, more generally speaking, the relative angle between rings and their grooves, has great influence on ring/groove contact characteristics, ring stability, and blowby. Ring flutter is found to occur for the second ring with a negative static twist under normal operating conditions and for the top ring with a negative static twist under high-speed/low-load operating conditions. Studies on a diesel engine show that different keystone ring/groove configurations result in different twist behaviors of the ring that may affect the wear pattern of the keystone ring running surfaces.

  15. Comments on collision mechanics in ring systems. [planetary rings

    NASA Technical Reports Server (NTRS)

    Hartmann, W. K.

    1982-01-01

    Collisions within planetary ring systems, especially Saturn's, are discussed. The particles may have coherent icy cores and less coherent granular or frosty surface layers, consistent with thermal eclipse observations. Collisions do not cause catastrophic fragmentation of the particles, although minor surface erosion and reaccretion is possible. Evolution by collisional fragmentation is thus not as important as in the asteroid belt. Models suggest that the fractional number of projectile masses dislodged when solid (or solid-core) projectiles strike solid ice or granular surface layers does not exceed the order of 10 to the minus 7th to minus 9th power. Even at this rate, the half life of ring particles would be less than the age of the solar system in crowded ring regions unless there was very efficient reaccretion. A plausible ring particle model involves solid ice cores with granular surface layers that exchange material by slow erosion and efficient reaccretion; the granular layers protect the cores from rapid erosion.

  16. Voyager 2 and the Uranian rings

    SciTech Connect

    Porco, C.C.

    1986-12-01

    Voyager 2 data on the Uranian disk system are presented and examined. The disk system consists of nine narrow rings, ranging in width from a few km to about 100 km. The Uranian rings are eccentric, inclined to the planet's equatorial plane, and precessing. The Uranian ring characteristics detected in the Voyager data are described and compared with those of the Saturn rings. The origin and maintenance of the rings are discussed, and the particle distribution in the ring system is studied.

  17. The role of resonances in planetary rings

    NASA Technical Reports Server (NTRS)

    Borderies, N.

    1987-01-01

    The new observations of planetary rings, including those acquired during the encounters of Voyager with Jupiter, Saturn, and Uranus, and the discovery of incomplete rings around Neptune, reveal the great importance of resonances in determining the dynamics and the shape of planetary rings. Several types of resonances play a part in planetary rings. Current questions of interest are related to the nonlinear theory of density waves, the confinement of the Uranian rings, and the arcs of rings around Neptune.

  18. Soft Congruence Relations over Rings

    PubMed Central

    Xin, Xiaolong; Li, Wenting

    2014-01-01

    Molodtsov introduced the concept of soft sets, which can be seen as a new mathematical tool for dealing with uncertainty. In this paper, we initiate the study of soft congruence relations by using the soft set theory. The notions of soft quotient rings, generalized soft ideals and generalized soft quotient rings, are introduced, and several related properties are investigated. Also, we obtain a one-to-one correspondence between soft congruence relations and idealistic soft rings and a one-to-one correspondence between soft congruence relations and soft ideals. In particular, the first, second, and third soft isomorphism theorems are established, respectively. PMID:24949493

  19. Reflex ring laser amplifier system

    DOEpatents

    Summers, Mark A.

    1985-01-01

    A laser pulse is injected into an unstable ring resonator-amplifier structure. Inside this resonator the laser pulse is amplified, spatially filtered and magnified. The laser pulse is recirculated in the resonator, being amplified, filtered and magnified on each pass. The magnification is chosen so that the beam passes through the amplifier in concentric non-overlapping regions similar to a single pass MOPA. After a number of passes around the ring resonator the laser pulse is spatially large enough to exit the ring resonator system by passing around an output mirror.

  20. Electromagnetic effects on planetary rings

    SciTech Connect

    Morfill, G.E.

    1983-01-01

    The role of electromagnetic effects in planetary rings is reviewed. The rings consist of a collection of solid particles with a size spectrum ranging from submicron to 10's of meters (at least in the case of Saturn's rings). Due to the interaction with the ambient plasma, and solar UV radiation, the particles carry electrical charges. Interactions of particles with the planetary electromagnetic field, both singly and collectively, are described, as well as the reactions and influence on plasma transients. The latter leads to a theory for the formation of Saturn's spokes, which is briefly reviewed.

  1. Codes over infinite family of rings : Equivalence and invariant ring

    NASA Astrophysics Data System (ADS)

    Irwansyah, Muchtadi-Alamsyah, Intan; Muchlis, Ahmad; Barra, Aleams; Suprijanto, Djoko

    2016-02-01

    In this paper, we study codes over the ring Bk=𝔽pr[v1,…,vk]/(vi2=vi,∀i =1 ,…,k ) . For instance, we focus on two topics, i.e. characterization of the equivalent condition between two codes over Bk using a Gray map into codes over finite field 𝔽pr, and finding generators for invariant ring of Hamming weight enumerator for Euclidean self-dual codes over Bk.

  2. Progress Report on the g-2 Storage Ring Magnet System

    SciTech Connect

    Bunce, G.A.; Cullen, J.; Danby, G.; Green, M.A.; Jackson, J.; Jia, L.; Krienen, F.; Meier, R.; Meng, W.; Morse, W.; Pai, C.; Polk, I.; Prodell, A.; Shutt, R.; Snydstrup, L.; Yamamoto, A.

    1995-06-01

    The 3.1 GeV muon storage ring for the g-2 experiment at Brookhaven National Laboratory has three large solenoid magnets that form a continuous 1.451 tesla storage ring dipole with an average beam bend radius of 7.1 meters. In addition to the three storage ring solenoids, there is an inflector dipole with nested dipole coils that create very little stray magnetic field. A superconducting shield on the inflector gets rid of most of the remaining stray flux. This paper reports on the progress made on the storage ring solenoid magnet system and the inflector as of June 1995. The results of cryogenic system tests are briefly reported.

  3. Of Rings and Volcanoes

    NASA Astrophysics Data System (ADS)

    2002-01-01

    Office National d'Etudes et de Recherches Aérospatiales (ONERA) , Laboratoire d'Astrophysique de Grenoble (LAOG) and the DESPA and DASGAL laboratories of the Observatoire de Paris in France, in collaboration with ESO. The CONICA infra-red camera was built, under an ESO contract, by the Max-Planck-Institut für Astronomie (MPIA) (Heidelberg) and the Max-Planck Institut für Extraterrestrische Physik (MPE) (Garching) in Germany, in collaboration with ESO. Saturn - Lord of the rings ESO PR Photo 04a/02 ESO PR Photo 04a/02 [Preview - JPEG: 460 x 400 pix - 54k] [Normal - JPEG: 1034 x 800 pix - 200k] Caption : PR Photo 04a/02 shows the giant planet Saturn, as observed with the VLT NAOS-CONICA Adaptive Optics instrument on December 8, 2001; the distance was 1209 million km. It is a composite of exposures in two near-infrared wavebands (H and K) and displays well the intricate, banded structure of the planetary atmosphere and the rings. Note also the dark spot at the south pole at the bottom of the image. One of the moons, Tethys, is visible as a small point of light below the planet. It was used to guide the telescope and to perform the adaptive optics "refocussing" for this observation. More details in the text. Technical information about this photo is available below. This NAOS/CONICA image of Saturn ( PR Photo 04a/02 ), the second-largest planet in the solar system, was obtained at a time when Saturn was close to summer solstice in the southern hemisphere. At this moment, the tilt of the rings was about as large as it can be, allowing the best possible view of the planet's South Pole. That area was on Saturn's night side in 1982 and could therefore not be photographed during the Voyager encounter. The dark spot close to the South Pole is a remarkable structure that measures approximately 300 km across. It was only recently observed in visible light from the ground with a telescope at the Pic du Midi Observatory in the Pyrenees (France) - this is the first infrared image to

  4. Stability of Moonlets Embedded in Rings

    NASA Astrophysics Data System (ADS)

    Lewis, Mark C.; Burdon, C.

    2011-04-01

    Previous work on moonlets assumed that they were just a single indestructible spherical particle and focused primarily on the effects such a body would have on the surrounding ring material (Lewis and Stewart 2009, Icarus 199:387-412; Sremcevic et al. 2007, Nature 449:1019-1021). Both observations and numerical simulations of Saturn's small inner moons show them as very low density rubble piles (Porco et al. 2007, Science 318:1602). Unlike the small moons, moonlets embedded in the ring material will experience regular collisions with self gravity wakes tens of meters across. Even with a single spherical core, these collisions can lead to the shedding of significant amounts of accreted material. We describe numerical simulations in which we explore the parameters required for stability of moonlets embedded in the ring material. Because of their location well inside the Roche limit, these bodies require either higher densities or some internal strength in order to stay together. We explore how much strength is required for these moonlets to be stable against the regular impacts they sustain in that environment. This work was funded by NSF AAG award number 0907972.

  5. Molecular ring rotation in solid ferrocene revisited

    NASA Astrophysics Data System (ADS)

    Appel, Markus; Frick, Bernhard; Spehr, Tinka Luise; Stühn, Bernd

    2015-03-01

    We report on quasielastic neutron spectroscopy experiments on ferrocene (bis(η5-cyclopentadienyl)iron) in its three different crystalline phases: the disordered monoclinic crystalline phase (T > 164 K), the metastable triclinic phase (T < 164 K), and the stable orthorhombic phase (T < 250 K). The cyclopentadienyl rings in ferrocene are known to undergo rotational reorientations for which the analysis of our large data set suggests partially a revision of the known picture of the dynamics and allows for an extension and completion of previous studies. In the monoclinic phase, guided by structural information, we propose a model for rotational jumps among non-equivalent sites in contrast to the established 5-fold jump rotation model. The new model takes the dynamical disorder into account and allows the cyclopentadienyl rings to reside in two different configurations which are found to be twisted by an angle of approximately 30°. In the triclinic phase, our analysis demands the use of a 2-ring model accounting for crystallographically independent sites with different barriers to rotation. For the orthorhombic phase of ferrocene, we confirm a significantly increased barrier of rotation using neutron backscattering spectroscopy. Our data analysis includes multiple scattering corrections and presents a novel approach of simultaneous analysis of different neutron scattering data by combining elastic and inelastic fixed window temperature scans with energy spectra, providing a very robust and reliable mean of extracting the individual activation energies of overlapping processes.

  6. Molecular ring rotation in solid ferrocene revisited

    SciTech Connect

    Appel, Markus; Frick, Bernhard; Spehr, Tinka Luise; Stühn, Bernd

    2015-03-21

    We report on quasielastic neutron spectroscopy experiments on ferrocene (bis(η{sup 5}-cyclopentadienyl)iron) in its three different crystalline phases: the disordered monoclinic crystalline phase (T > 164 K), the metastable triclinic phase (T < 164 K), and the stable orthorhombic phase (T < 250 K). The cyclopentadienyl rings in ferrocene are known to undergo rotational reorientations for which the analysis of our large data set suggests partially a revision of the known picture of the dynamics and allows for an extension and completion of previous studies. In the monoclinic phase, guided by structural information, we propose a model for rotational jumps among non-equivalent sites in contrast to the established 5-fold jump rotation model. The new model takes the dynamical disorder into account and allows the cyclopentadienyl rings to reside in two different configurations which are found to be twisted by an angle of approximately 30°. In the triclinic phase, our analysis demands the use of a 2-ring model accounting for crystallographically independent sites with different barriers to rotation. For the orthorhombic phase of ferrocene, we confirm a significantly increased barrier of rotation using neutron backscattering spectroscopy. Our data analysis includes multiple scattering corrections and presents a novel approach of simultaneous analysis of different neutron scattering data by combining elastic and inelastic fixed window temperature scans with energy spectra, providing a very robust and reliable mean of extracting the individual activation energies of overlapping processes.

  7. Black rings at large D

    NASA Astrophysics Data System (ADS)

    Tanabe, Kentaro

    2016-02-01

    We study the effective theory of slowly rotating black holes at the infinite limit of the spacetime dimension D. This large D effective theory is obtained by integrating the Einstein equation with respect to the radial direction. The effective theory gives equations for non-linear dynamical deformations of a slowly rotating black hole by effective equations. The effective equations contain the slowly rotating Myers-Perry black hole, slowly boosted black string, non-uniform black string and black ring as stationary solutions. We obtain the analytic solution of the black ring by solving effective equations. Furthermore, by perturbation analysis of effective equations, we find a quasinormal mode condition of the black ring in analytic way. As a result we confirm that thin black ring is unstable against non-axisymmetric perturbations. We also include 1 /D corrections to the effective equations and discuss the effects by 1 /D corrections.

  8. Perturbations of vortex ring pairs

    NASA Astrophysics Data System (ADS)

    Gubser, Steven S.; Horn, Bart; Parikh, Sarthak

    2016-02-01

    We study pairs of coaxial vortex rings starting from the action for a classical bosonic string in a three-form background. We complete earlier work on the phase diagram of classical orbits by explicitly considering the case where the circulations of the two vortex rings are equal and opposite. We then go on to study perturbations, focusing on cases where the relevant four-dimensional transfer matrix splits into two-dimensional blocks. When the circulations of the rings have the same sign, instabilities are mostly limited to wavelengths smaller than a dynamically generated length scale at which single-ring instabilities occur. When the circulations have the opposite sign, larger wavelength instabilities can occur.

  9. Ring resonant cavities for spectroscopy

    DOEpatents

    Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.; Xie, Jinchun

    1999-01-01

    Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS).

  10. MUON STORAGE RINGS - NEUTRINO FACTORIES

    SciTech Connect

    PARSA,Z.

    2000-05-30

    The concept of a muon storage ring based Neutrino Source (Neutrino Factory) has sparked considerable interest in the High Energy Physics community. Besides providing a first phase of a muon collider facility, it would generate more intense and well collimated neutrino beams than currently available. The BNL-AGS or some other proton driver would provide an intense proton beam that hits a target, produces pions that decay into muons. The muons must be cooled, accelerated and injected into a storage ring with a long straight section where they decay. The decays occurring in the straight sections of the ring would generate neutrino beams that could be directed to detectors located thousands of kilometers away, allowing studies of neutrino oscillations with precisions not currently accessible. For example, with the neutrino source at BNL, detectors at Soudan, Minnesota (1,715 km), and Gran Sasso, Italy (6,527 km) become very interesting possibilities. The feasibility of constructing and operating such a muon-storage-ring based Neutrino-Factory, including geotechnical questions related to building non-planar storage rings (e.g. at 8{degree} angle for BNL-Soudan, and 3{degree} angle for BNL-Gran Sasso) along with the design of the muon capture, cooling, acceleration, and storage ring for such a facility is being explored by the growing Neutrino Factory and Muon Collider Collaboration (NFMCC). The authors present overview of Neutrino Factory concept based on a muon storage ring, its components, physics opportunities, possible upgrade to a full muon collider, latest simulations of front-end, and a new bowtie-muon storage ring design.

  11. Ring resonant cavities for spectroscopy

    DOEpatents

    Zare, R.N.; Martin, J.; Paldus, B.A.; Xie, J.

    1999-06-15

    Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS). 6 figs.

  12. Resonance capture and Saturn's rings

    SciTech Connect

    Patterson, C.W.

    1986-05-01

    We have assigned the resonances apparently responsible for the stabilization of the Saturn's shepherd satellites and for the substructure seen in the F-ring and the ringlets in the C-ring. We show that Saturn's narrow ringlets have a substructure determined by three-body resonances with Saturn's ringmoons and the sun. We believe such resonances have important implications to satellite formation. 17 refs., 1 fig., 1 tab.

  13. Collector ring project at FAIR

    NASA Astrophysics Data System (ADS)

    Dolinskii, A.; Berkaev, D.; Blell, U.; Dimopoulou, C.; Gorda, O.; Leibrock, H.; Litvinov, S.; Laier, U.; Koop, I.; Schurig, I.; Starostenko, A.; Shatunov, P.; Weinrich, U.

    2015-11-01

    The collector ring is a dedicated ring for fast cooling of ions coming from separators at the FAIR project. To accommodate optimal technical solutions, a structure of a magnet lattice was recently reviewed and modified. Consequently, more appropriate technical solutions for the main magnets could be adopted. A general layout and design of the present machine is shown. The demanding extraction schemes have been detailed and open design issues were completed.

  14. Density waves in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.; Lissauer, J. J.; Shu, F. H.

    1981-08-01

    Certain radial brightness variations in the outer Cassini division of Saturn's rings may be spiral density waves driven by Saturn's large moon Iapetus, in which case a value of approximately 16 g/sq cm for the surface density is calculated in the region where the waves are seen. The kinematic viscosity in the same region is approximately 170 sq cm/s and the vertical scale height of the ring is estimated to be a maximum of approximately 40 m.

  15. Compound fiber ring resonator: Theory

    SciTech Connect

    Zhang, J.; Lit, J.W.Y.

    1994-06-01

    A compound fiber ring resonator is made with a Fabry-Perot etalon built inside a fiber ring that is fed through a 2 x 2 directional single-mode fiber coupler. It is theoretically analyzed by an unfolded equivalent model and a transfer-matrix method. The output intensities are presented, and four cases are discussed. The results may be useful in applications such as fiber spectrum analyzers, sensors, and lasers. 25 refs., 9 figs.

  16. Chordal Reconstruction versus Leaflet Resection for Repair of Degenerative Posterior Mitral Leaflet Prolapse

    PubMed Central

    Chua, Yeow Leng; Yap, Yen Ping; Salam, Zakir Hussain Abdul; Chen, Yang Tian

    2015-01-01

    Objective: To review our experience of mitral valve repair for degenerative posterior mitral leaflet prolapse, comparing the outcomes of chordal reconstruction and leaflet resection. Methods: From 2000 to 2014, 205 patients underwent successful repair for degenerative posterior mitral leaflet prolapse. One hundred and four (51.5%) underwent leaflet resection (group R) and 98 (48.5%) underwent chordal reconstruction (group C). Follow-up was 96.5% complete with a mean follow-up of 6.1 ± 4.0 years. Results: Mean age was 57.0 ± 11.0 years. Males accounted for 73.8%. Ring annuloplasty was performed in 195 (96.5%). There were no operative mortalities within 30 days. Overall survival was 97.8% ± 1.3% at 7 years. Outcomes at 6 years: freedom from severe mitral regurgitation (group R 97.1% ± 2.0%, group C 100%, P = 0.288), freedom from moderate or severe mitral regurgitation (group R 97.1% ± 2.0%, group C 94.4% ± 5.4%, P = 0.541). Group C patients received larger annuloplasty rings and had significantly lower postoperative transmitral gradients. Conclusions: Leaflet resection and chordal reconstruction are effective techniques for repair of degenerative posterior mitral leaflet prolapse. Both techniques result in a low incidence of recurrent mitral regurgitation. Chordal reconstruction accommodates larger annuloplasty rings and is associated with lower transmitral gradients. PMID:26727025

  17. An integrated model of ring pack performance

    NASA Technical Reports Server (NTRS)

    Keribar, R.; Dursunkaya, Z.; Flemming, M. F.

    1991-01-01

    This paper describes an integrated model developed for the detailed characterization and simulation of piston ring pack behavior in internal combustion engines and the prediction of ring pack performance. The model includes comprehensive and coupled treatments of (1) ring-liner hydrodynamic and boundary lubrication and friction; (2) ring axial, radial, and (toroidal) twist dynamics; (3) inter-ring gas dynamics and blowby. The physics of each of these highly inter-related phenomena are represented by submodels, which are intimately coupled to form a design-oriented predictive tool aimed at the calculation of ring film thicknesses, ring motions, land pressures, engine friction, and blowby. The paper also describes the results of a series of analytical studies investigating effects of engine speed and load and ring pack design parameters, on ring motions, film thicknesses, and inter-ring pressures, as well as ring friction and blowby.

  18. 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.

  19. Physics of Jupiter's Gossamer Rings

    NASA Astrophysics Data System (ADS)

    Hamilton, Douglas P.; Krueger, H.

    2007-10-01

    Thebe's gossamer ring, the outermost and faintest of Jupiter's rings, has an outward extension that we have previously argued is due to a shadow resonance (Hamilton 2003, DPS meeting #35, #11.09). A shadow resonance arises from the abrupt shutoff of photoelectric charging when a dust particle enters Jupiter's shadow which, in turn, affects the strength of the electromagnetic perturbation from the planet's intense magnetic field. The result is a coupled oscillation between a particle's orbital eccentricity and its semimajor axis. Ring material spreads outward from Thebe while maintaining its vertical thickness just as observed by Galileo imaging. In addition to cameras, the Galileo spacecraft was also equipped with dust and plasma detectors. The spacecraft made two passes through the ring and its dust detector found that 1) dust fluxes drop immediately interior to Thebe's orbit, 2) some grains have inclinations in excess of 20 degrees and 3) submicron particles are present in the Amalthea ring in much greater numbers than in the Thebe ring. These findings can all be explained in the context of our shadow resonance model: the inner boundary is a direct consequence of the conservation of the Electromagnetic Jacobi Constant, the high inclinations are forced by a vertical resonance, and the excess submicron particles are a consequence of the weakening of electromagnetic forces in the vicinity of synchronous orbit. In this talk, we will present the data sets as well as detailed numerical simulations that back up these claims.

  20. First Evidence of Jupiter Ring

    NASA Technical Reports Server (NTRS)

    1979-01-01

    First evidence of a ring around the planet Jupiter is seen in this photograph taken by Voyager 1 on March 4, 1979. The multiple exposure of the extremely thin faint ring appears as a broad light band crossing the center of the picture. The edge of the ring is 1,212,000 km from the spacecraft and 57,000 km from the visible cloud deck of Jupiter. The background stars look like broken hair pins because of spacecraft motion during the 11 minute 12 second exposure. The wavy motion of the star trails is due to the ultra-slow natural oscillation of the spacecraft (with a period of 78 seconds). The black dots are geometric calibration points in the camera. The ring thickness is estimated to be 30 km or less. The photograph was part of a sequence planned to search for such rings in Jupiter's equatorial plane. The ring has been invisible from Earth because of its thinness and its transparency when viewed at any angle except straight on. JPL manages and controls the Voyager Project for NASA's Office of Space Science.

  1. Of Rings and Volcanoes

    NASA Astrophysics Data System (ADS)

    2002-01-01

    Office National d'Etudes et de Recherches Aérospatiales (ONERA) , Laboratoire d'Astrophysique de Grenoble (LAOG) and the DESPA and DASGAL laboratories of the Observatoire de Paris in France, in collaboration with ESO. The CONICA infra-red camera was built, under an ESO contract, by the Max-Planck-Institut für Astronomie (MPIA) (Heidelberg) and the Max-Planck Institut für Extraterrestrische Physik (MPE) (Garching) in Germany, in collaboration with ESO. Saturn - Lord of the rings ESO PR Photo 04a/02 ESO PR Photo 04a/02 [Preview - JPEG: 460 x 400 pix - 54k] [Normal - JPEG: 1034 x 800 pix - 200k] Caption : PR Photo 04a/02 shows the giant planet Saturn, as observed with the VLT NAOS-CONICA Adaptive Optics instrument on December 8, 2001; the distance was 1209 million km. It is a composite of exposures in two near-infrared wavebands (H and K) and displays well the intricate, banded structure of the planetary atmosphere and the rings. Note also the dark spot at the south pole at the bottom of the image. One of the moons, Tethys, is visible as a small point of light below the planet. It was used to guide the telescope and to perform the adaptive optics "refocussing" for this observation. More details in the text. Technical information about this photo is available below. This NAOS/CONICA image of Saturn ( PR Photo 04a/02 ), the second-largest planet in the solar system, was obtained at a time when Saturn was close to summer solstice in the southern hemisphere. At this moment, the tilt of the rings was about as large as it can be, allowing the best possible view of the planet's South Pole. That area was on Saturn's night side in 1982 and could therefore not be photographed during the Voyager encounter. The dark spot close to the South Pole is a remarkable structure that measures approximately 300 km across. It was only recently observed in visible light from the ground with a telescope at the Pic du Midi Observatory in the Pyrenees (France) - this is the first infrared image to

  2. APS Storage Ring vacuum chamber fabrication

    SciTech Connect

    Goeppner, G.A.

    1990-01-01

    The 1104-m circumference Advanced Photon Source Storage Ring Vacuum System is composed of 240 individual sections, which are fabricated from a combination of aluminum extrusions and machined components. The vacuum chambers will have 3800 weld joints, each subject to strict vacuum requirements, as well as a variety of related design criteria. The vacuum criteria and chamber design are reviewed, including a discussion of the weld joint geometries. The critical fabrication process parameters for meeting the design requirements are discussed. The experiences of the prototype chamber fabrication program are presented. Finally, the required facilities preparation for construction activity is briefly described. 6 refs., 6 figs., 1 tab.

  3. Cerenkov ring imaging detector development: Progress report

    SciTech Connect

    Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.; Ratcliff, B.

    1988-10-01

    We present recent progress on the construction and testing of the first drift boxes and single electron detectors as they come from the production line. These detectors will be used for particle identification using the Ring Imaging technique in the SLD experiment at SLAC. Various experimental results are presented, including single electron pulse height measurements as a function of gas gain, detector gating capability, uniformity of response across the wire plane, charge division performance of a single electron signal, average pulse shape and its comparison with predicted shape, and cross-talk. 14 refs., 11 figs.

  4. FLSR - The Frankfurt low energy storage ring

    NASA Astrophysics Data System (ADS)

    Stiebing, K. E.; Alexandrov, V.; Dörner, R.; Enz, S.; Kazarinov, N. Yu.; Kruppi, T.; Schempp, A.; Schmidt Böcking, H.; Völp, M.; Ziel, P.; Dworak, M.; Dilfer, W.

    2010-02-01

    An electrostatic storage ring for low-energy ions with a design energy of 50 keV is presently being set up at the Institut für Kernphysik der Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany (IKF). This new device will provide a basis for new experiments on the dynamics of ionic and molecular collisions, as well as for high precision and time resolved laser spectroscopy. In this article, the design parameters of this instrument are reported.

  5. Accretion in Saturn's F Ring

    NASA Astrophysics Data System (ADS)

    Meinke, B. K.; Esposito, L. W.; Stewart, G.

    2012-12-01

    Saturn's F ring is the solar system's principal natural laboratory for direct observation of accretion and disruption processes. The ring resides in the Roche zone, where tidal disruption competes with self-gravity, which allows us to observe the lifecycle of moonlets. Just as nearby moons create structure at the B ring edge (Esposito et al. 2012) and the Keeler gap (Murray 2007), the F ring "shepherding" moons Prometheus and Pandora stir up ring material and create observably changing structures on timescales of days to decades. In fact, Beurle et al (2010) show that Prometheus makes it possible for "distended, yet gravitationally coherent clumps" to form in the F ring, and Barbara and Esposito (2002) predicted a population of ~1 km bodies in the ring. In addition to the observations over the last three decades, the Cassini Ultraviolet Imaging Spectrograph (UVIS) has detected 27 statistically significant features in 101 occultations by Saturn's F ring since July 2004. Seventeen of those 27 features are associated with clumps of ring material. Two features are opaque in occultation, which makes them candidates for solid objects, which we refer to as Moonlets. The 15 other features partially block stellar signal for 22 m to just over 3.7 km along the radial expanse of the occultation. Upon visual inspection of the occultation profile, these features resemble Icicles, thus we will refer to them as such here. The density enhancements responsible for such signal attenuations are likely due to transient clumping of material, evidence that aggregations of material are ubiquitous in the F ring. Our lengthy observing campaign reveals that Icicles are likely transient clumps, while Moonlets are possible solid objects. Optical depth is an indicator of clumping because more-densely aggregated material blocks more light; therefore, it is natural to imagine moonlets as later evolutionary stage of icicle, when looser clumps of material compact to form a feature that appears

  6. Interaction of multiple co-axial co-rotating vortex rings

    NASA Astrophysics Data System (ADS)

    Qin, Suyang; Liu, Hong; Liu, Xiaoyu; Xiang, Yang

    2015-11-01

    Fish and birds gain hydrodynamic force from a wake of discrete or linked vortex chain, which is the existence form of vortex rings in nature. Vortex rings with the same formation time are generated successively with different time interval by a piston-cylinder arrangement, and the velocity fields are measured using DPIV. The motion of multiple interacting vortex rings is first reported in laboratorial experiments. Besides the most attracting leapfrogging phenomenon, two other phenomena, suction and weak influence, are also clearly presented using the method of Lagrangian coherent structures. Due to the induced effect of wake vortex rings, the formation process of the forming vortex rings is different from that of a single isolated vortex ring, indicating that another distinct timescale exists, together with formation number proposed by Gharib (1998 JFM), determining the mechanisms of vortex rings. When the rear vortex ring leapfrogs, the limiting case is that the rear contracting ring is axis-touching. If an axis-touching ring is further squeezed by the wake vortex, the vortex structure will collapse, which can be explained by Kelvin-Benjamin variational principle. According to this principle, it is impossible for two optimal formed vortex rings to leapfrog. Financial support from the State Key Development Program of Basic Research of China (2014CB744802) is gratefully acknowledged.

  7. 21 CFR 872.5550 - Teething ring.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Teething ring. 872.5550 Section 872.5550 Food and... DENTAL DEVICES Therapeutic Devices § 872.5550 Teething ring. (a) Identification. A teething ring is a...) Classification. Class I if the teething ring does not contain a fluid, such as water. The device is exempt...

  8. 21 CFR 872.5550 - Teething ring.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Teething ring. 872.5550 Section 872.5550 Food and... DENTAL DEVICES Therapeutic Devices § 872.5550 Teething ring. (a) Identification. A teething ring is a...) Classification. Class I if the teething ring does not contain a fluid, such as water. The device is exempt...

  9. 21 CFR 872.5550 - Teething ring.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Teething ring. 872.5550 Section 872.5550 Food and... DENTAL DEVICES Therapeutic Devices § 872.5550 Teething ring. (a) Identification. A teething ring is a...) Classification. Class I if the teething ring does not contain a fluid, such as water. The device is exempt...

  10. 21 CFR 872.5550 - Teething ring.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Teething ring. 872.5550 Section 872.5550 Food and... DENTAL DEVICES Therapeutic Devices § 872.5550 Teething ring. (a) Identification. A teething ring is a...) Classification. Class I if the teething ring does not contain a fluid, such as water. The device is exempt...

  11. Reinforcement core facilitates O-ring installation

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Reinforcement core holds O-ring in place within a structure while adjacent parts are being assembled. The core in the O-ring adds circumferential rigidity to the O-ring material. This inner core does not appreciably affect the sectional elasticity or gland-sealing characteristics of the O-ring.

  12. Plasma deposited rider rings for hot displacer

    DOEpatents

    Kroebig, Helmut L.

    1976-01-01

    A hot cylinder for a cryogenic refrigerator having two plasma spray deposited rider rings of a corrosion and abrasion resistant material provided in the rider ring grooves, wherein the rider rings are machined to the desired diameter and width after deposition. The rider rings have gas flow flats machined on their outer surface.

  13. Double acting stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1986-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  14. Planetary Rings: Circular and Non-circular

    NASA Astrophysics Data System (ADS)

    French, R. G.; Nicholson, P. D.; Colwell, J.; Marouf, E. A.; Rappaport, N. J.; Hedman, M. M.; McGhee, C.; Lonergan, K.; Sepersky, T.

    2011-12-01

    Although Saturn's rings appear at first glance to be axisymmetric, more precise measurements reveal that many of the gap edges and narrow ringlets within the rings are noncircular, a characteristic they share with the narrow uranian rings. A careful study of these features is of interest for several reasons: (i) resonantly-forced perturbations are believed to prevent the rings from spreading under the influence of collisions, (ii) unforced distortions, mostly eccentricities, can lead to estimates of the surface mass density and viscosity of the rings, and (iii) accurately-measured apsidal precession rates provide information on Saturn's zonal gravity harmonics. We present preliminary results from a comprehensive study of noncircular features in the Cassini Division and in the C ring. The data used in this study come from three Cassini experiments, and cover the period from May 2005 to September 2010. Over 120 stellar occultations have been observed by the Ultraviolet Imaging Spectrometer (UVIS) and by the Visual and Infrared Imaging Spectrometer (VIMS). In addition, we include 12 occultations of the spacecraft's radio Radio Science Subsystem (RSS) by the rings observed on Earth in May-September 2005. The simplest noncircular features can be modeled as inclined Keplerian ellipses, freely precessing under the influence of Saturn's oblate gravity field. In agreement with similar fits to the VIMS occultation data alone, we find that the inner edges of 7 of the 8 gaps within the Cassini Division are eccentric, with amplitudes ranging from 0.9 km to 28.3 km. In contrast, most of the outer gap edges are near-circular. We also find a rich assortment of normal modes on the edges of both ringlets and gaps. We have searched for modes with wavenumber m as high as 8, and find convincing evidence for modes with m = 0, 2, 3, 4 and 5, all with amplitudes of 1 km or greater. In some cases, as many as 3 or 4 normal modes coexist at a single edge with comparable amplitudes. Our fits

  15. Concentric ring flywheel without expansion separators

    DOEpatents

    Kuklo, T.C.

    1999-08-24

    A concentric ring flywheel wherein the adjacent rings are configured to eliminate the need for differential expansion separators between the adjacent rings. This is accomplished by forming a circumferential step on an outer surface of an inner concentric ring and forming a matching circumferential step on the inner surface of an adjacent outer concentric ring. During operation the circumferential steps allow the rings to differentially expand due to the difference in the radius of the rings without the formation of gaps therebetween, thereby eliminating the need for expansion separators to take up the gaps formed by differential expansion. 3 figs.

  16. Concentric ring flywheel without expansion separators

    DOEpatents

    Kuklo, Thomas C.

    1999-01-01

    A concentric ring flywheel wherein the adjacent rings are configured to eliminate the need for differential expansion separators between the adjacent rings. This is accomplished by forming a circumferential step on an outer surface of an inner concentric ring and forming a matching circumferential step on the inner surface of an adjacent outer concentric ring. During operation the circumferential steps allow the rings to differentially expand due to the difference in the radius of the rings without the formation of gaps therebetween, thereby eliminating the need for expansion separators to take up the gaps formed by differential expansion.

  17. ELISA - an electrostatic storage ring for low-energy ions

    NASA Astrophysics Data System (ADS)

    Pape Moeller, Soeren

    1997-05-01

    The design of a new type of storage ring for low-energy ions using electrostatic deflection and focusing devices is described. Electrostatic bends and quadrupoles are used since they are more efficient than magnetic ones for low-velocity heavy ions. Furthermore, electrostatic devices are more compact and easier to construct than magnetic devices. In comparison to an electromagnetic trap, one important advantage of the elecrostatic ring is the easy access to the circulating beam and its decay products. These and other features, e.g. no magnetic fields, makes such storage devices attractive for many atomic-physics experiments. Also neigboring fields as chemistry and biology might benefit from such an relatively inexpensive device. One important difference between an electrostatic and a magnetic ring is, that the longitudinal energy is not conserved for the electrostatic ring. The actual ring will have a race-track shape as defined by two straight sections each with two quadrupole doublets connected by 180-degrees bends. The bends will consist of 160-degrees spherical deflection plates surrounded by two parallel plate 10-degrees bends. The storage ring ELISA, currently being built, will have a circumference of 6 meters. The first beam tests will take place during summer 1996.

  18. Interaction of a vortex ring with a natural convective layer

    NASA Astrophysics Data System (ADS)

    Palacios-Morales, C. A.; Salinas, M.; Solorio-Ordaz, F. J.; Zenit, R.

    2013-11-01

    We study the dynamics and heat transfer resulting from the impact of a vortex ring with a vertical heated wall. Laminar vortex rings were generated in water with a piston- cylinder arrangement. The vertical wall is heated by a thermal bath which is held at constant temperature producing a laminar and stable thermal boundary layer. Measurements of the 2D velocity field were obtained with a TR-PIV technique and the scalar temperature field is obtained by the PLIF technique. To avoid azimuthal instabilities, we conducted experiments for small stroke rations and Re of O(1000). The initial circular shape evolves to an asymmetric shape after reaching the wall. The lower ring section thickens and separates from the wall while the upper part thins and is dragged by the thermal layer. On the sides, the vortex ring is stretched. The rate of change of circulation is small at the lower section of the ring indicating that the momentum transport and heat transfer is more significant in this region. The instantaneous heat transfer coefficient was obtained; as expected, when the vortex approaches the wall, the heat transfer increases mainly at the lower part of the ring.

  19. TSR: A storage and cooling ring for HIE-ISOLDE

    NASA Astrophysics Data System (ADS)

    Butler, P. A.; Blaum, K.; Davinson, T.; Flanagan, K.; Freeman, S. J.; Grieser, M.; Lazarus, I. H.; Litvinov, Yu. A.; Lotay, G.; Page, R. D.; Raabe, R.; Siesling, E.; Wenander, F.; Woods, P. J.

    2016-06-01

    It is planned to install the heavy-ion, low-energy ring TSR, currently at the Max-Planck-Institute for Nuclear Physics in Heidelberg, at the HIE-ISOLDE facility in CERN, Geneva. Such a facility will provide a capability for experiments with stored, cooled secondary beams that is rich and varied, spanning from studies of nuclear ground-state properties and reaction studies of astrophysical relevance, to investigations with highly-charged ions and pure isomeric beams. In addition to experiments performed using beams recirculating within the ring, the cooled beams can be extracted and exploited by external spectrometers for high-precision measurements. The capabilities of the ring facility as well as some physics cases will be presented, together with a brief report on the status of the project.

  20. Magnetic response measurements of mesoscopic superconducting and normal metal rings

    NASA Astrophysics Data System (ADS)

    Bluhm, Hendrik

    The main part of this thesis reports three experiments on the magnetic response of mesoscopic superconducting and normal metal rings using a scanning SQUID microscope. The first experiment explores the magnetic response and fluxoid transitions of superconducting, mesoscopic bilayer aluminum rings in the presence of two coupled order parameters arising from the layered structure. For intermediate couplings, metastable states that have different phase winding numbers around the ring in each of the two order parameters were observed. Larger coupling locks the relative phase, so that the two order parameters are only manifest in the temperature dependence of the response. With increasing proximitization, this signature gradually disappears. The data can be described with a two-order-parameter Ginzburg-Landau theory. The second experiment concentrates on fluxoid transitions in similar, but single-layer rings. Near the critical temperature, the transitions, which are induced by applying a flux to the ring, only admit a single fluxoid at a time. At lower temperatures, several fluxoids enter or leave at once, and the final state approaches the ground state. Currently available theoretical frameworks cannot quantitatively explain the data. Heating and quasiparticle diffusion are likely important for a quantitative understanding of this experiment, which could provide a model system for studying the nonlinear dynamics of superconductors far from equilibrium. The third and most important scanning SQUID study concerns 33 individual mesoscopic gold rings. All measured rings show a paramagnetic linear susceptibility and a poorly understood anomaly around zero field, both of which are likely due to unpaired defect spins. The response of sufficiently small rings also has a component that is periodic in the flux through the ring, with a period close to h/e. Its amplitude varies in sign and magnitude from ring to ring, and its typical value and temperature dependence agree with

  1. Numerical simulations supporting the process design of ring rolling processes

    NASA Astrophysics Data System (ADS)

    Jenkouk, V.; Hirt, G.; Seitz, J.

    2013-05-01

    In conventional Finite Element Analysis (FEA) of radial-axial ring rolling (RAR) the motions of all tools are usually defined prior to simulation in the preprocessing step. However, the real process holds up to 8 degrees of freedom (DOF) that are controlled by industrial control systems according to actual sensor values and preselected control strategies. Since the histories of the motions are unknown before the experiment and are dependent on sensor data, the conventional FEA cannot represent the process before experiment. In order to enable the usage of FEA in the process design stage, this approach integrates the industrially applied control algorithms of the real process including all relevant sensors and actuators into the FE model of ring rolling. Additionally, the process design of a novel process 'the axial profiling', in which a profiled roll is used for rolling axially profiled rings, is supported by FEA. Using this approach suitable control strategies can be tested in virtual environment before processing.

  2. Intrinsic structure in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Albers, N.

    2015-10-01

    Saturn's rings are the most prominent in our Solar system and one example of granular matter in space. Dominated by tides and inelastic collisions the system is highly flattened being almost 300000km wide while only tens of meters thick. Individual particles are composed of primarily water ice and range from microns to few tens of meters in size. Apparent patterns comprise ringlets, gaps, kinematic wakes, propellers, bending waves, and the winding spiral arms of density waves. These large-scale structures are perturbations foremost created by external as well as embedded moons. Observations made by the Cassini spacecraft currently in orbit around Saturn show these structures in unprecedented detail. But high-resolution measurements reveal the presence of small-scale structures throughout the system. These include self-gravity wakes (50-100m), overstable waves (100-300m), subkm structure at the A and B ring edges, "straw" and "ropy" structures (1-3km), and the C ring "ghosts". Most of these had not been anticipated and are found in perturbed regions, driven by resonances with external moons, where the system undergoes periodic phases of compression and relaxation that correlate with the presence of structure. High velocity dispersion and the presence of large clumps imply structure formation on time scales as short as one orbit (about 10 hours). The presence of these intrinsic structures is seemingly the response to varying local conditions such as internal density, optical depth, underlying particle size distribution, granular temperature, and distance from the central planet. Their abundance provides evidence for an active and dynamic ring system where aggregation and fragmentation are ongoing on orbital timescales. Thus a kinetic description of the rings may be more appropriate than the fluid one. I will present Cassini Ultraviolet Spectrometer (UVIS) High Speed Photometer (HSP) occultations, Voyager 1 and 2 Imaging Science Subsystem (ISS), and high

  3. Archiving of Planetary Ring Data

    NASA Technical Reports Server (NTRS)

    Elliot, James L.

    2001-01-01

    Stellar occultation data provide our only Earth-based means of probing planetary rings at kilometer spatial resolution. The occultation data archive at MIT contains original data and analysis products of stellar occultations by the ring systems of the planets Jupiter, Saturn, Uranus, and Neptune observed by members of the group (and other groups) from 1977 to the present. During this time period, several media have been used to record and store the original and processed data: (1) chart records; (2) printed output, (3) audio reel tape; (4) audio cassette tape; (5) 7-track, 1/2-inch computer tape; (6) 9-track, 1/2-inch computer tape at 800, 1600, and 6250 bpi; (7) NOVA disk platters (2.5 and 5.0 Mbyte); (8) write once optical disks; (9) punched cards; and (10) read-write optical disks. With the rapid change of computer technology over this time period, some of these media have become not only obsolete, but nearly extinct. In particular, it has become nearly impossible to find any facilities that can still read 800 bpi tapes, which contain the only copies of several important data sets for the ring system of Uranus. In particular, we have an extensive ring data collection that includes data sets for the following Uranian ring occultations: U0, U11, U12, U13, U14, U25, U17, and U36.

  4. Split ring containment attachment device

    SciTech Connect

    Sammel, A.G.

    1995-12-31

    A containment attachment device is described for operatively connecting a glovebag to plastic sheeting covering hazardous material. The device includes an inner split ring member connected on one end to a middle ring member wherein the free end of the split ring member is inserted through a slit in the plastic sheeting to captively engage a generally circular portion of the plastic sheeting. A collar portion having an outer ring portion is provided with fastening means for securing the device together wherein the glovebag is operatively connected to the collar portion. Hazardous material such as radioactive waste may be sealed in plastic bags for small items or wrapped in plastic sheeting for large items. Occasionally the need arises to access the hazardous material in a controlled manner, that is, while maintaining total containment. Small items could be placed entirely inside a containment glovebag. However, it may not be possible or practical to place large items inside a containment; instead, one or more glovebags could be attached to the plastic sheeting covering the hazardous material. It is this latter application for which the split ring containment attachment device is intended.

  5. Ring wormholes via duality rotations

    NASA Astrophysics Data System (ADS)

    Gibbons, Gary W.; Volkov, Mikhail S.

    2016-09-01

    We apply duality rotations and complex transformations to the Schwarzschild metric to obtain wormhole geometries with two asymptotically flat regions connected by a throat. In the simplest case these are the well-known wormholes supported by phantom scalar field. Further duality rotations remove the scalar field to yield less well known vacuum metrics of the oblate Zipoy-Voorhees-Weyl class, which describe ring wormholes. The ring encircles the wormhole throat and can have any radius, whereas its tension is always negative and should be less than -c4 / 4 G. If the tension reaches the maximal value, the geometry becomes exactly flat, but the topology remains non-trivial and corresponds to two copies of Minkowski space glued together along the disk encircled by the ring. The geodesics are straight lines, and those which traverse the ring get to the other universe. The ring therefore literally produces a hole in space. Such wormholes could perhaps be created by negative energies concentrated in toroidal volumes, for example by vacuum fluctuations.

  6. Ring Beholds a Delicate Flower

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Spitzer Space Telescope finds a delicate flower in the Ring Nebula, as shown in this image. The outer shell of this planetary nebula looks surprisingly similar to the delicate petals of a camellia blossom. A planetary nebula is a shell of material ejected from a dying star. Located about 2,000 light years from Earth in the constellation Lyra, the Ring Nebula is also known as Messier Object 57 and NGC 6720. It is one of the best examples of a planetary nebula and a favorite target of amateur astronomers.

    The 'ring' is a thick cylinder of glowing gas and dust around the doomed star. As the star begins to run out of fuel, its core becomes smaller and hotter, boiling off its outer layers. The telescope's infrared array camera detected this material expelled from the withering star. Previous images of the Ring Nebula taken by visible-light telescopes usually showed just the inner glowing loop of gas around the star. The outer regions are especially prominent in this new image because Spitzer sees the infrared light from hydrogen molecules. The molecules emit infrared light because they have absorbed ultraviolet radiation from the star or have been heated by the wind from the star.

    Download the QuickTime movie for the animated version of this Ring Nebula image.

  7. Softened-Stainless-Steel O-Rings

    NASA Technical Reports Server (NTRS)

    Marquis, G. A.; Waters, William I.

    1993-01-01

    In fabrication of O-ring of new type, tube of 304 stainless steel bent around mandril into circle and welded closed into ring. Ring annealed in furnace to make it soft and highly ductile. In this condition, used as crushable, deformable O-ring seal. O-ring replacements used in variety of atmospheres and temperatures, relatively inexpensive, fabricated with minimum amount of work, amenable to one-of-a-kind production, reusable, and environmentally benign.

  8. Remote Sensing of Dipole Rings

    NASA Technical Reports Server (NTRS)

    Hooker, Stanford B.; Mied, Richard P.; Brown, James W.; Kirwan, A. D., Jr.

    1997-01-01

    Historical satellite-derived sea surface temperature (SST) data are reanalyzed with a zebra color palette and a thermal separatrix method. The new results from this reanalysis are as follows: (a) Thirteen observational sequences of six rings from the Gulf Stream and the Brazil Current, which have historically been interpreted as solitary vortices or monopoles are shown to have a dipolar character; (b) some of these dipole rings have been observed in the open ocean, thereby eliminating the possibility that they are sustained by topographic interactions with the continental slope; (c) whether interacting with other features or evolving as isolated circulations, dipoles are seen to rotate within a relatively narrow range of approximately 4-8 deg/day (interacting) and 10-11 deg/day (isolated); and (d) feature tracking delineates energetic fluid in both vortices and eliminates the possibility of interpreting dipole rings as transient features produced by active monopoles and patches of entrained fluid.

  9. New Main Ring control system

    SciTech Connect

    Seino, K.; Anderson, L.; Ducar, R.; Franck, A.; Gomilar, J.; Hendricks, B.; Smedinghoff, J.

    1990-03-01

    The Fermilab Main Ring control system has been operational for over sixteen years. Aging and obsolescence of the equipment make the maintenance difficult. Since the advent of the Tevatron, considerable upgrades have been made to the controls of all the Fermilab accelerators except the Main Ring. Modernization of the equipment and standardization of the hardware and software have thus become inevitable. The Tevatron CAMAC serial system has been chosen as a basic foundation in order to make the Main Ring control system compatible with the rest of the accelerator complex. New hardware pieces including intelligent CAMAC modules have been designed to satisfy unique requirements. Fiber optic cable and repeaters have been installed in order to accommodate new channel requirements onto the already saturated communication medium system. 8 refs., 2 figs.

  10. Physics of Jupiter's Gossamer Rings

    NASA Astrophysics Data System (ADS)

    Hamilton, Douglas P.; Krueger, H.

    2008-05-01

    Thebe's gossamer ring, the outermost and faintest of Jupiter's rings, extends outward by at least half a jovian radius from its source satellite while maintaining a constant vertical thickness. This structure is created by an electromagnetic perturbation known as a shadow resonance (Hamilton 2003, DPS meeting #35, #11.09). A shadow resonance arises from the abrupt shutoff of photoelectric charging when a dust particle enters Jupiter's shadow which, in turn, affects the strength of the electromagnetic perturbation from the planet's intense magnetic field. The result is a coupled oscillation between a particle's orbital eccentricity and its semimajor axis. Ring material spreads outward from Thebe while maintaining its vertical thickness just as observed by Galileo imaging. In addition to cameras, the Galileo spacecraft was also equipped with dust and plasma detectors. The spacecraft made two passes through the ring and its dust detector found that 1) dust fluxes drop immediately interior to Thebe's orbit, 2) some grains have inclinations in excess of 20 degrees and 3) submicron particles are present in the Amalthea ring in much greater numbers than in the Thebe ring. These findings can all be explained in the context of our shadow resonance model: the inner boundary is a direct consequence of the conservation of the Electromagnetic Jacobi Constant, the high inclinations are forced by a vertical version of the shadow resonance, and the excess submicron particles are a consequence of the weakening of electromagnetic forces in the vicinity of synchronous orbit. In this talk, we will present the data sets as well as detailed numerical simulations that back up these claims.

  11. Ynamides in Ring Forming Transformations

    PubMed Central

    WANG, XIAO-NA; YEOM, HYUN-SUK; FANG, LI-CHAO; HE, SHUZHONG; MA, ZHI-XIONG; KEDROWSKI, BRANT L.; HSUNG, RICHARD P.

    2013-01-01

    Conspectus The ynamide functional group activates carbon-carbon triple bonds through an attached nitrogen atom that bears an electron-withdrawing group. As a result, the alkyne has both electrophilic and nucleophilic properties. Through the selection of the electron-withdrawing group attached to nitrogen chemists can modulate the electronic properties and reactivity of ynamides, making these groups versatile synthetic building blocks. The reactions of ynamides also lead directly to nitrogen-containing products, which provides access to important structural motifs found in natural products and molecules of medicinal interest. Therefore, researchers have invested increasing time and research in the chemistry of ynamides in recent years. This Account surveys and assesses new organic transformations involving ynamides developed in our laboratory and in others around the world. We showcase the synthetic power of ynamides for rapid assembly of complex molecular structures. Among the recent reports of ynamide transformations, ring-forming reactions provide a powerful tool for generating molecular complexity quickly. In addition to their synthetic utility, such reactions are mechanistically interesting. Therefore, we focus primarily on the cyclization chemistry of ynamides. This Account highlights ynamide reactions that are useful in the rapid synthesis of cyclic and polycyclic structural manifolds. We discuss the mechanisms active in the ring formations and describe representative examples that demonstrate the scope of these reactions and provide mechanistic insights. In this discussion we feature examples of ynamide reactions involving radical cyclizations, ring-closing metathesis, transition metal and non-transition metal mediated cyclizations, cycloaddition reactions, and rearrangements. The transformations presented rapidly introduce structural complexity and include nitrogen within, or in close proximity to, a newly formed ring (or rings). Thus, ynamides have emerged

  12. Power Supplies for Precooler Ring

    SciTech Connect

    Fuja, Raymond; Praeg, Walter

    1980-12-12

    Eight power supplies will energize the antiproton Precooler ring. there will be two series connected supplies per quadrant. These supplies will power 32 dipole and 19 quadrupole magnets. The resistance and inductance per quadrant is R = 1.4045 Ohms and L = 0.466. Each powr supply will have 12-phase series bridge rectifiers and will be energized from the 480 V 3-phase grid. The total of eight power supplies are numbered IA, IIA, IIIA, IVA, and IB, IIB, IIIB, and IVB. Each quadrant will contain one A and one B supply. A block diagram of the Precooler ring with its power supplies is shown in Figure 1.

  13. Adult presentation with vascular ring due to double aortic arch.

    PubMed

    Kafka, Henryk; Uebing, Anselm; Mohiaddin, Raad

    2006-11-01

    This is a case report on the use of cardiovascular magnetic resonance imaging to diagnose vascular ring due to double aortic arch in an adult presenting with an abnormal chest X-ray. The experience in this case and the literature review identify the benefits of using cardiovascular magnetic resonance imaging to clarify complex aortic arch anatomy.

  14. Multiple Coulomb ordered strings of ions in a storage ring.

    PubMed

    Hasse, R W

    2001-04-01

    We explain that the anomalous frequency shifts of very close masses obtained in the high precision mass measurement experiments in the ESR storage ring result from the locking of Coulomb interacting strings of ions. Here two concentric strings which run horizontally close to each other are captured into a single string if their thermal clouds overlap and give up their identity.

  15. Rings Around the Sun and Moon: Coronae and Diffraction

    ERIC Educational Resources Information Center

    Cowley, Les; Laven, Philip; Vollmer, Michael

    2005-01-01

    Atmospheric optical effects can teach much about physics and especially optics. Coronae--coloured rings around the sun or moon--are large-scale consequences of diffraction, which is often thought of as only a small effect confined to the laboratory. We describe coronae, how they are formed and experiments that can be conducted on ones in the sky.…

  16. Electromagnetic ring expansion as a high-rate test: Experimental development

    SciTech Connect

    Gourdin, W.H.; Weinland, S.L.; Boling, R.M.

    1987-07-07

    We describe improvements to the electromagnetically launched expanding ring experiment that makes it reproducible, analyzable, and amenable to the rapid testing of many specimens. Primary concerns are the design and containment of the solenoid, high-voltage switching of the capacitor, and electromagnetic and expansion-speed diagnostics. We demonstrate the reproducibility of the technique on carefully processed OFHC copper rings.

  17. Acousto-optic modulator as an electronically selectable unidirectional device in a ring laser

    SciTech Connect

    Roy, R.; Schulz, P.A.; Walther, A.

    1987-09-01

    An acousto-optic modulator causes undirectional operation of dye and Ti:sapphire ring lasers. The modulator has a low insertion loss in the cavity and can be used to switch the direction of the beam electronically. The ring laser performance is characterized, and experiments to probe the origin of the unidirectional operation are described.

  18. A Experimental Study of Viscous Vortex Rings.

    NASA Astrophysics Data System (ADS)

    Dziedzic, Mauricio

    Motivated by the role played by vortex rings in the process of turbulent mixing, the work is focused on the problem of stability and viscous decay of a single vortex ring. A new classification is proposed for vortex rings which is based on extensive hot-wire measurements of velocity in the ring core and wake and flow visualization. Vortex rings can be classified as laminar, wavy, turbulence-producing, and turbulent. Prediction of vortex ring type is shown to be possible based on the vortex ring Reynolds number. Linear growth rates of ring diameter with time are observed for all types of vortex rings, with different growth rates occurring for laminar and turbulent vortex rings. Data on the viscous decay of vortex rings are used to provide experimental confirmation of the accuracy of Saffman's equation for the velocity of propagation of a vortex ring. Experimental data indicate that instability of the vortex ring strongly depends on the mode of generation and can be delayed by properly adjusting the generation parameters. A systematic review of the literature on vortex-ring interactions is presented in the form of an appendix, which helps identify areas in which further research may be fruitful.

  19. The Promise of Intravaginal Rings for Prevention: User Perceptions of Biomechanical Properties and Implications for Prevention Product Development.

    PubMed

    Morrow Guthrie, Kate; Vargas, Sara; Shaw, Julia G; Rosen, Rochelle K; van den Berg, Jacob J; Kiser, Patrick F; Buckheit, Karen; Bregman, Dana; Thompson, Lara; Jensen, Kathleen; Johnson, Todd; Buckheit, Robert W

    2015-01-01

    Intravaginal rings (IVRs) are currently under investigation as devices for the delivery of agents to protect against the sexual transmission of HIV and STIs, as well as pregnancy. To assist product developers in creating highly acceptable rings, we sought to identify characteristics that intravaginal ring users consider when making decisions about ring use or non-use. We conducted four semi-structured focus groups with 21 women (aged 18-45) who reported using an IVR in the past 12 months. Participants manipulated four prototype rings in their hands, discussed ring materials, dimensionality, and "behavior," and shared perceptions and appraisals. Five salient ring characteristics were identified: 1) appearance of the rings' surfaces, 2) tactile sensations of the cylinder material, 3) materials properties, 4) diameter of the cylinder, and 5) ring circumference. Pliability (or flexibility) was generally considered the most important mechanical property. Several ring properties (e.g., porousness, dimensionality) were associated with perceptions of efficacy. Women also revealed user behaviors that may impact the effectiveness of certain drugs, such as removing, rinsing and re-inserting the ring while bathing, and removing the ring during sexual encounters. As product developers explore IVRs as prevention delivery systems, it is critical to balance product materials and dimensions with use parameters to optimize drug delivery and the user experience. It is also critical to consider how user behaviors (e.g., removing the ring) might impact drug delivery. PMID:26695431

  20. Impact of a vortex ring on a wall with a circular cutout

    NASA Astrophysics Data System (ADS)

    Hu, Jiacheng; Peterson, Sean D.

    2015-11-01

    The rising interests in the development of small-scale energy harvesters have prompted research efforts into fluid interactions with highly deformable materials, with a few studies utilizing vortex rings as the energy source. In particular, Hu et al. (JIMSS, 2014) investigated a vortex ring impacting a concentric deformable annulus and found that a smaller ring appears and propagates away post impact. However, due to the fixture of the structure, the interaction process was not captured. The present study is a follow-up experiment to elucidate the smaller ring formation using a rigid wall with a circular cutout. We observe that the smaller ring is formed out of the induced vorticity at the cutout tip. Furthermore, despite the cutout, the classical vortex ring - wall interaction still occurs, wherein the induced boundary layer on the impact side of the wall ejects secondary and tertiary rings near the wall. Interestingly, when the cutout is shifted off-center, the wall splits the original ring into two portions. The portion that passes through the hole connects with the induced vorticity at the cutout tip, forms a new ring, and propagates away at an angle; the blocked portion follows the classical vortex ring - wall interaction.

  1. Conical O-ring seal

    DOEpatents

    Chalfant, Jr., Gordon G.

    1984-01-01

    A shipping container for radioactive or other hazardous materials which has a conical-shaped closure containing grooves in the conical surface thereof and an O-ring seal incorporated in each of such grooves. The closure and seal provide a much stronger, tighter and compact containment than with a conventional flanged joint.

  2. Ring Network with VLAN Tag

    NASA Astrophysics Data System (ADS)

    Shimizu, Hiroshi

    The proposed Ring Network with VLAN Tag offers the features of wrapping/steering control functions and 1+1 path protection function, keeping the compatibility with Ethernet media access control scheme. The key technology for “Path concept” is VLAN tag swapping operation. A set of primary and back-up paths is defined between ring nodes, which are distinguished by a flag bit in VLAN tag field. On failure detection, the path is switched within the path set by the tag swapping. Tag swapping at the failure detection node, while tag swapping at the source node achieves staring operation, achieves Wrapping operation. The restoration behavior is almost the same as that of Resilient Packet Ring (RPR). Since the tag swapping control is based on hardware processing, high-speed operation is also expected. Furthermore, because the paths are independently designed from the physical topology, the scheme can be applied to other networks than physical ring networks. The proposed scheme will fit to the path control for next generation Ethernet over WDM system.

  3. Conical O-ring seal

    DOEpatents

    Chalfant, G.G. Jr.

    A shipping container for radioactive or other hazardous materials has a conical-shaped closure containing grooves in the conical surface thereof and an O-ring seal incorporated in each of such grooves. The closure and seal provide a much stronger, tighter and compact containment than with a conventional flanged joint.

  4. The composition and structure of planetary rings

    NASA Technical Reports Server (NTRS)

    Burns, J. A.

    1985-01-01

    The properties of planetary ring systems are summarized herein; emphasis is given to the available evidence on their compositions and to their dynamical attributes. Somewhat contaminated water ice makes up the vast expanse of Saturn's rings. Modified methane ice may comprise Uranus' rings while silicates are the likely material of the Jovian ring. Saturn's rings form an elaborate system whose characteristics are still being documented and whose nature is being unravelled following the Voyager flybys. Uranus' nine narrow bands display an intriguing dynamical structure thought to be caused by unseen shephard satellites. Jupiter's ring system is a mere wisp, probably derived as ejecta off hidden parent bodies.

  5. Cavity-locked ring down spectroscopy

    DOEpatents

    Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

    2000-01-01

    Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

  6. The formation of Jupiter's faint rings

    PubMed

    Burns; Showalter; Hamilton; Nicholson; de Pater I; Ockert-Bell; Thomas

    1999-05-14

    Observations by the Galileo spacecraft and the Keck telescope showed that Jupiter's outermost (gossamer) ring is actually two rings circumscribed by the orbits of the small satellites Amalthea and Thebe. The gossamer rings' unique morphology-especially the rectangular end profiles at the satellite's orbit and the enhanced intensities along the top and bottom edges of the rings-can be explained by collisional ejecta lost from the inclined satellites. The ejecta evolves inward under Poynting-Robertson drag. This mechanism may also explain the origin of Jupiter's main ring and suggests that faint rings may accompany all small inner satellites of the other jovian planets.

  7. The formation of Jupiter's faint rings

    PubMed

    Burns; Showalter; Hamilton; Nicholson; de Pater I; Ockert-Bell; Thomas

    1999-05-14

    Observations by the Galileo spacecraft and the Keck telescope showed that Jupiter's outermost (gossamer) ring is actually two rings circumscribed by the orbits of the small satellites Amalthea and Thebe. The gossamer rings' unique morphology-especially the rectangular end profiles at the satellite's orbit and the enhanced intensities along the top and bottom edges of the rings-can be explained by collisional ejecta lost from the inclined satellites. The ejecta evolves inward under Poynting-Robertson drag. This mechanism may also explain the origin of Jupiter's main ring and suggests that faint rings may accompany all small inner satellites of the other jovian planets. PMID:10325220

  8. Multiwavelength studies of Saturn's rings

    NASA Astrophysics Data System (ADS)

    Spilker, L. J.; Deau, E.; Filacchione, G.; Morishima, R.; Hedman, M. M.; Nicholson, D.; Colwell, J. E.

    2013-12-01

    Modeling the changes in brightness, color, temperature and spectral parameters, significant progress can be made in understanding the character of Saturn's ring particles and their regoliths with changing viewing geometry. We are studying Saturn's rings over a wide range of wavelengths, from ultraviolet through the thermal infrared. Data from Cassini's Composite Infrared Spectrometer (CIRS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS) and Ultraviolet Imaging Spectrograph (UVIS) are jointly being studied using scans of the lit and unlit main rings (A, B, C and Cassini Division) at multiple geometries and solar elevations. Phase curves are also being generated for different ring regions. Using multi-wavelength data sets allows us to test different thermal models by combining effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, and particle spin rate and spin axis orientation. With the high spatial resolution of the Cassini data it is now possible to analyze these effects at smaller spatial scales and characterize regions such as the C ring plateaus and ringlets, where albedo differences may be present. The CIRS temperature and ISS color variations are confined primarily to phase angle over a range of solar elevations with only small differences from changing spacecraft elevation. Color and temperature dependence with varying solar elevation angle are also observed. Brightness dependence with changing solar elevation angle and phase angle is observed with UVIS. VIMS observations show that IR water ice absorption band depths are a very weak function of phase angle, out to ~140 deg phase, suggesting that interparticle light scattering is relatively unimportant except at very high phase angles. These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The

  9. The axial motion of a piston ring in the piston ring groove

    SciTech Connect

    Brownawell, M E

    1983-06-01

    The piston ring axial motion model developed by Furuhama, Dowson and Hoult was modified using the parallel plate squeeze equation to account for oil in the ring grooves. The improved model was used to predict ring motion and the ring transition time from one ring land to the other. The ring axial motion was measured in detail on an engine with a clear plexiglas cylinder using a high-speed motion picture camera. The observed ring motion and transit times were compared to those predicted by the new model. The model was found to correctly predict the motion of the rings and the scaling with lubricant viscosity and engine speed.

  10. High-Speed Ring Bus

    NASA Technical Reports Server (NTRS)

    Wysocky, Terry; Kopf, Edward, Jr.; Katanyoutananti, Sunant; Steiner, Carl; Balian, Harry

    2010-01-01

    The high-speed ring bus at the Jet Propulsion Laboratory (JPL) allows for future growth trends in spacecraft seen with future scientific missions. This innovation constitutes an enhancement of the 1393 bus as documented in the Institute of Electrical and Electronics Engineers (IEEE) 1393-1999 standard for a spaceborne fiber-optic data bus. It allows for high-bandwidth and time synchronization of all nodes on the ring. The JPL ring bus allows for interconnection of active units with autonomous operation and increased fault handling at high bandwidths. It minimizes the flight software interface with an intelligent physical layer design that has few states to manage as well as simplified testability. The design will soon be documented in the AS-1393 standard (Serial Hi-Rel Ring Network for Aerospace Applications). The framework is designed for "Class A" spacecraft operation and provides redundant data paths. It is based on "fault containment regions" and "redundant functional regions (RFR)" and has a method for allocating cables that completely supports the redundancy in spacecraft design, allowing for a complete RFR to fail. This design reduces the mass of the bus by incorporating both the Control Unit and the Data Unit in the same hardware. The standard uses ATM (asynchronous transfer mode) packets, standardized by ITU-T, ANSI, ETSI, and the ATM Forum. The IEEE-1393 standard uses the UNI form of the packet and provides no protection for the data portion of the cell. The JPL design adds optional formatting to this data portion. This design extends fault protection beyond that of the interconnect. This includes adding protection to the data portion that is contained within the Bus Interface Units (BIUs) and by adding to the signal interface between the Data Host and the JPL 1393 Ring Bus. Data transfer on the ring bus does not involve a master or initiator. Following bus protocol, any BIU may transmit data on the ring whenever it has data received from its host. There

  11. A new method for beam stacking in storage rings

    SciTech Connect

    Bhat, C.M.; /Fermilab

    2008-06-01

    Recently, I developed a new beam stacking scheme for synchrotron storage rings called 'longitudinal phase-space coating' (LPSC). This scheme has been convincingly validated by multi-particle beam dynamics simulations and has been demonstrated with beam experiments at the Fermilab Recycler. Here, I present the results from both simulations and experiments. The beam stacking scheme presented here is the first of its kind.

  12. Secular instability of Saturn's rings.

    NASA Astrophysics Data System (ADS)

    Griv, E.; Chiueh, T.

    1996-07-01

    Kinetic theory with the Boltzmann and Poisson's equations is used to determine the stability and oscillations of the two-dimensional collisional system of identical particles of Saturn's rings. The effects of physical collisions between particles are taken into account by using in the Bolztmann kinetic equation a phenomenological Bhatnagar-Gross-Krook collisional integral (Bhatnagar et al. 1954). This model collisional integral was modified following Shu & Stewart (1985) to allow collisions to be inelastic. The dynamics of a system with rare collisions is considered, that is, {OMEGA}^2^>>ν_c_^2^, with {OMEGA} being the orbital angular frequency and ν_c_ the collision frequency. It is shown that in a Jeans-stable system the simultaneous action of self-gravity and collisions leads to a secular dissipative type instability. It is also shown that generally the growth rate of this aperiodic instability is small, Im ω_*_~ν_c_. However, in the marginally Jeans-stable gravitationally parts of the disk, the growth rate is a maximum, and may become a large, Im ω_*_=~(ν_cOMEGA^2^)^1/3^>>ν_c_. In such parts of the Saturn's system the instability will develop on the time scale only of several revolutions even at moderately low values of the local optical depth, τ=~ν_c_/{OMEGA}~0.1. The radial wavelength of the most unstable oscillations is of the order λ=~2πρ, where ρ=~c/{OMEGA} is the epicyclic radius and c is the mean dispersion of random velocities of particles. The secular instability may be suggested as the cause of much of the irregular, narrow ~2πρ~100m structure in low optical depth regions of Saturn's rings. Cassini spacecraft high-resolution images may resolve such hyperfine structure in the C ring, the inner B ring and the A ring.

  13. F Ring Mini-Jets

    NASA Astrophysics Data System (ADS)

    Attree, N.; Murray, C.; Cooper, N. J.; Williams, G.

    2012-12-01

    Mini-jets are small, (~50 km) linear features observed in Cassini images to be emanating from Saturn's F ring; they are believed to be produced by collisions with a local population of moonlets. An analysis of one such feature, observed over the course of a ~7.5 h sequence as its length changed from ~75 km to ~250 km while it simultaneously appeared to collapse back into the core, supports the collisional theory of their origin [1]. Orbit determination suggests that this mini-jet consisted of ring material displaced by a ~1 m/s collision with a nearby object, resulting in paths relative to the core that are due to a combination of keplerian shear and epicyclic motion. The colliding object itself is likely to be too small to resolve in these images but represents just one member of a population of F ring moonlets. Such a population has been investigated by UVIS occultations [2], and other methods, but generally remains unresolved in Cassini images. Collisional features such as this mini-jet therefore provide an additional tracer for the region's moonlet population. In this talk we will present the results of recent work in measuring and describing a subset of ~350 catalogued mini-jets, applying knowledge gained from the original mini-jet feature. Their distribution in space and time, proximity to Prometheus and evolution are all examined in an effort to place constraints on the properties of the underlying population of colliding objects. References [1] N. O. Attree, C. D. Murray, N. J. Cooper, and G. A. Williams. Detection of low velocity collisions in Saturn's F ring. Ap. J. Lett. (In press). [1] B. K. Meinke, L. W. Esposito, N. Albers, and M. Sremevi. Classification of F ring features observed in cassini UVIS occultations. Icarus, 218(1):545 - 554, 2012.

  14. A secure WDM ring access network employing silicon micro-ring based remote node

    NASA Astrophysics Data System (ADS)

    Sung, Jiun-Yu; Chow, Chi-Wai; Yeh, Chien-Hung; Xu, Ke; Hsu, Chin-Wei; Su, Hong-Quan; Tsang, Hon-Ki

    2014-08-01

    A secure and scalable wavelength-division-multiplexing (WDM) ring-based access network is proposed and demonstrated using proof-of-concept experiments. In the remote node (RN), wavelength hopping for specific optical networking unit (ONU) is deployed by using silicon micro-ring resonators (SMR). Using silicon-based devices could be cost-effective for the cost-sensitive access network. Hence the optical physical layer security is introduced. The issues of denial of service (DOS) attacks, eavesdropping and masquerading can be made more difficult in the proposed WDM ring-based access network. Besides, the SMRs with different dropped wavelengths can be cascaded, such that the signals pass through the preceding SMRs can be dropped by a succeeding SMR. This can increase the scalability of the RN for supporting more ONUs for future upgrade. Here, error-free 10 Gb/s downlink and 1.25 Gb/s uplink transmission are demonstrated to show the feasibility of the proposed network.

  15. Wear reduction systems liquid piston ring

    SciTech Connect

    Raymond, R.J.; Chen, T.N.; DiNanno, L.

    1990-09-01

    The overall objective of the program was to demonstrate the technical feasibility of achieving an acceptable wear rate for the cylinder liner, piston, and piston rings in a coal/water-slurry-fueled engine that utilized the concept of a liquid piston ring above the conventional piston rings and to identify technical barriers and required research and development. The study included analytical modeling of the system, a bench study of the fluid motion in the liquid piston ring, and a single-cylinder test rig for wear comparison. A system analysis made on the different variations of the liquid supply system showed the desirability of the once-through version from the standpoint of system simplicity. The dynamics of the liquid ring were modeled to determine the important design parameters that influence the pressure fluctuation in the liquid ring during a complete engine cycle and the integrity of the liquid ring. This analysis indicated the importance of controlling heat transfer to the liquid ring through piston and liner to avoid boiling the liquid. A conceptual piston design for minimizing heat transfer is presented in this report. Results showed that the liquid piston ring effectively reduced the solid particles on the wall by scrubbing, especially in the case where a surfactant was added to the water. The wear rates were reduced by a factor of 2 with the liquid ring. However, leakage of the contaminated liquid ring material past the top ring limited the effectiveness of the liquid ring concept. 8 refs., 33 figs., 1 tab.

  16. An Energy Recovery Electron Linac On Ring Collider

    SciTech Connect

    Nikolitsa Merminga; Geoffrey Krafft; Valeri Lebedev; Ilan Ben-Zvi

    2001-09-01

    Electron-proton/ion colliders with center of mass energies between 14 GeV and 100 GeV (protons) or 63 GeV/A (ions) and luminosities at the 10{sup 33} (per nucleon) level have been proposed recently as a means for studying hadronic structure. Electron beam polarization appears to be crucial for many of the experiments. Two accelerator design scenarios have been examined in detail: colliding rings and recirculating linac-on-ring. Although the linac-on-ring scenario is not as well developed as the ring-ring scenario, comparable luminosities appear feasible. The linac-on-ring option presents significant advantages with respect to: (1) spin manipulations; (2) reduction of the synchrotron radiation load in the detectors; (3) a wide range of continuous energy variability. Rf power and beam dump considerations require that the electron linac recover the beam energy. This technology has been demonstrated at Jefferson Lab's IR FEL with cw current up to 5 mA and beam energy up to 50 MeV. Based on extrapolations from actual measurements and calculations, energy recovery is expected to be feasible at higher currents (a few hundred mA) and higher energies (a few GeV) as well. The report begins with a brief overview of Jefferson Lab's experience with energy recovery and summarize its benefits. Luminosity projections for the linac-ring scenario based on fundamental limitations are presented next. The feasibility of an energy recovery electron linac-on-proton ring collider is investigated and four conceptual point designs are shown corresponding to electron to proton energies of: 3 GeV on 15 GeV, 5 GeV on 50 GeV and 10 GeV on 250 GeV, and for gold ions with 100 GeV/A. The last two designs assume that the protons or ions are stored in the existing RHIC accelerator. Accelerator physics issues relevant to proton rings and energy recovery linacs are discussed next and a list of required R and D for the realization of such a design is presented.

  17. Evaluation of ring capacitor plates for regional deep heating.

    PubMed

    Van Rhoon, G C; Visser, A G; Van den Berg, P M; Reinhold, H S

    1988-01-01

    Based upon a capacitive system a quasi-microwave cavity operating at a frequency of 13.56 or 27.12 MHz has been developed. The prototype consisted of two capacitive plates with a circular aperture at the centre of each plate in which a cylindrically shaped tissue volume can be placed. Phantom measurements showed that a second-generation applicator, consisting of two narrow rings with equal inner and outer diameter, gave identical results. Due to the positioning of the rings along the enclosed tissue cylinder, the electrical field is mainly parallel to the body axis. SAR distributions were measured by infrared thermography in cylindrical, muscle equivalent phantoms enclosed in PVC-tubes using the 'split phantom' technique. For phantom diameters up to 13.5 cm a homogeneous heating, SAR 70-100 per cent of the maximum SAR, has been obtained over the tissue volume between the inner edges of the two rings. For these measurements the non-isolated ring electrodes are placed directly onto the PVC cover. When the phantom diameter, excluding PVC cover, is increased to 22.5 cm the SAR values at the centre vary from 30 to 40 per cent of the maximum SAR value which is located near the inner edge of the rings. In this case a 1 cm gap between the rings and the PVC cover was used in order to reduce the intensity of the hot spots. In all experiments no cooling of the phantom surface or ring electrodes has been used. The results from this initiating study indicate the feasibility of this type of applicator for regional deep heating, although more experimental work is needed when the applicator is used to heat tissue bodies with a diameter larger than 13.5 cm. Already, the applicator in its most simple design may be of clinical value for hyperthermic treatment of tumors in arms or legs.

  18. The Canarias Einstein ring: a newly discovered optical Einstein ring

    NASA Astrophysics Data System (ADS)

    Bettinelli, M.; Simioni, M.; Aparicio, A.; Hidalgo, S. L.; Cassisi, S.; Walker, A. R.; Piotto, G.; Valdes, F.

    2016-09-01

    We report the discovery of an optical Einstein ring in the Sculptor constellation, IAC J010127-334319, in the vicinity of the Sculptor dwarf spheroidal galaxy. It is an almost complete ring (˜300°) with a diameter of ˜4.5 arcsec. The discovery was made serendipitously from inspecting Dark Energy Camera (DECam) archive imaging data. Confirmation of the object nature has been obtained by deriving spectroscopic redshifts for both components, lens and source, from observations at the 10.4 m Gran Telescopio CANARIAS (GTC) with the spectrograph OSIRIS. The lens, a massive early-type galaxy, has a redshift of z = 0.581, while the source is a starburst galaxy with redshift of z = 1.165. The total enclosed mass that produces the lensing effect has been estimated to be Mtot = (1.86 ± 0.23) × 1012 M⊙.

  19. Mass production of shaped particles through vortex ring freezing

    NASA Astrophysics Data System (ADS)

    An, Duo; Warning, Alex; Yancey, Kenneth G.; Chang, Chun-Ti; Kern, Vanessa R.; Datta, Ashim K.; Steen, Paul H.; Luo, Dan; Ma, Minglin

    2016-08-01

    A vortex ring is a torus-shaped fluidic vortex. During its formation, the fluid experiences a rich variety of intriguing geometrical intermediates from spherical to toroidal. Here we show that these constantly changing intermediates can be `frozen' at controlled time points into particles with various unusual and unprecedented shapes. These novel vortex ring-derived particles, are mass-produced by employing a simple and inexpensive electrospraying technique, with their sizes well controlled from hundreds of microns to millimetres. Guided further by theoretical analyses and a laminar multiphase fluid flow simulation, we show that this freezing approach is applicable to a broad range of materials from organic polysaccharides to inorganic nanoparticles. We demonstrate the unique advantages of these vortex ring-derived particles in several applications including cell encapsulation, three-dimensional cell culture, and cell-free protein production. Moreover, compartmentalization and ordered-structures composed of these novel particles are all achieved, creating opportunities to engineer more sophisticated hierarchical materials.

  20. Experimental measurement of noncovalent interactions between halogens and aromatic rings.

    PubMed

    Adams, Harry; Cockroft, Scott L; Guardigli, Claudio; Hunter, Christopher A; Lawson, Kevin R; Perkins, Julie; Spey, Sharon E; Urch, Christopher J; Ford, Rhonan

    2004-05-01

    Chemical double mutant cycles have been used to quantify the interactions of halogens with the faces of aromatic rings in chloroform. The halogens are forced over the face of an aromatic ring by an array of hydrogen-bonding interactions that lock the complexes in a single, well-defined conformation. These interactions can also be engineered into the crystal structures of simpler model compounds, but experiments in solution show that the halogen-aromatic interactions observed in the solid state are all unfavourable, regardless of whether the aromatic rings contain electron-withdrawing or electron-donating substituents. The halogen-aromatic interactions are repulsive by 1-3 kJ mol(-1). The interactions with fluorine are slightly less favourable than with chlorine and bromine.

  1. Mass production of shaped particles through vortex ring freezing.

    PubMed

    An, Duo; Warning, Alex; Yancey, Kenneth G; Chang, Chun-Ti; Kern, Vanessa R; Datta, Ashim K; Steen, Paul H; Luo, Dan; Ma, Minglin

    2016-01-01

    A vortex ring is a torus-shaped fluidic vortex. During its formation, the fluid experiences a rich variety of intriguing geometrical intermediates from spherical to toroidal. Here we show that these constantly changing intermediates can be 'frozen' at controlled time points into particles with various unusual and unprecedented shapes. These novel vortex ring-derived particles, are mass-produced by employing a simple and inexpensive electrospraying technique, with their sizes well controlled from hundreds of microns to millimetres. Guided further by theoretical analyses and a laminar multiphase fluid flow simulation, we show that this freezing approach is applicable to a broad range of materials from organic polysaccharides to inorganic nanoparticles. We demonstrate the unique advantages of these vortex ring-derived particles in several applications including cell encapsulation, three-dimensional cell culture, and cell-free protein production. Moreover, compartmentalization and ordered-structures composed of these novel particles are all achieved, creating opportunities to engineer more sophisticated hierarchical materials.

  2. SRB O-ring free response analysis

    NASA Technical Reports Server (NTRS)

    Moore, Carleton J.

    1986-01-01

    The free response of viton O-rings were investigated. Two different response mechanisms of viton O-rings are identified and a theoretical representation of the two mechanisms is compared with experimental results for various temperatures.

  3. How to Remove a Stuck Ring Safely

    MedlinePlus

    ... Fireworks Safety Lawnmower Safety Snowblower safety Pumpkin Carving Gardening Safety Turkey Carving Removing a Ring Español Artritis ... Fireworks Safety Lawnmower Safety Snowblower safety Pumpkin Carving Gardening Safety Turkey Carving Removing a Ring Español Artritis ...

  4. Planetary science: Shepherds of Saturn's ring

    NASA Astrophysics Data System (ADS)

    Crida, Aurélien

    2015-09-01

    Saturn's F ring is chaperoned on both sides by the tiny moons Prometheus and Pandora. Numerical simulations show that this celestial ballet can result from the collision of two aggregates that evolved out of Saturn's main rings.

  5. Thermally activated phase slips from metastable states in mesoscopic superconducting rings

    NASA Astrophysics Data System (ADS)

    Petkovic, Ivana; Lollo, Anthony; Harris, Jack

    In equilibrium, a flux-biased superconducting ring at low temperature can occupy any of several metastable states. The particular state that the ring occupies depends on the history of the applied flux, as different states are separated from each other by flux-dependent energy barriers. There is a critical value of the applied flux at which a given barrier goes to zero, the state becomes unstable, and the system transition into another state. In recent experiments performed on arrays of rings we showed that this transition occurs close to the critical flux predicted by Ginzburg-Landau theory. Here, we will describe experiments in which we have extended these measurements to an individual ring in order to study the thermal activation of the ring over a barrier that has been tuned close to zero. We measure the statistics of transitions as function of temperature and ramp rate.

  6. Temperature variation of Saturn's Rings with Solar Elevation

    NASA Astrophysics Data System (ADS)

    Flandes, A.; Spilker, L.; Altobelli, N.; Leyrat, C.; Pilorz, S.; Edgington, S. G.

    2008-12-01

    In its four-year orbit around Saturn, the spacecraft Cassini has achieved a large number of infrared observations of Saturn's main rings through the CIRS experiment (Cassini Composite Infrared Spectrometer). We analyze the change of temperature in the main rings (A, B and C) as function of the solar elevation with respect to the plane of the rings at very low (<6°) and high (>120°) phase angles. Specific regions of every ring were chosen in every case to rule out other effects that may produce variations in temperature as well and to account only effects due to the solar latitudinal variations. For solar elevations that cover a range from -10.1° to -23.5°, in average, the temperature variations of the A, B and C rings are around ~{8 K}, near ~{12 K} and barely ~{3 K} respectively. Simple analytical functions which depend on the solar elevation angle and the heliocentric distance are used to fit the trends observed in the data assuming either a continuous slab or idependent particle models. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA and at CEA Saclay supported by the "Programme National de Planetologie". Copyright 2008 California Institute of Technology. Government sponsorship acknowledged.

  7. Wireless optics protection of fiber via SONET ring closure

    NASA Astrophysics Data System (ADS)

    Mullen, Ruth Ann; Celmer, Ken T.; Foster, Michael; Wooten, Jimmie; Miller, Jared; Kean, John C.; Carter, Doug; Kefauver, Michael; Singh, Bhupendra; Achour, Maha; Willebrand, Heinz A.

    2001-02-01

    12 A free-space laser link closes an otherwise all-fiber SONET ring, demonstrating for the first time the feasibility of using wireless optics as a back-up to fiber in an application demanding the highest levels of statistical availability and sub-50-ms protection-restoral times. This experiment demonstrates that protocol-transparent wireless optical links can be readily internetworked with industry- standard fiber-based protection protocols to achieve SONET restoral times in the event of a fiber cut. By using the wireless optics as a back-up to fiber rather than as the primary link, end-users are normally protected from the unavoidable burst errors and outages that can arise on a wireless optical link in the event of anomalously poor atmospheric visibility or unanticipated line-of-sight obstructions. While an all-fiber SONET ring operating over physically diverse paths is generally preferred, hybrid fiber/air rings operating over physically-diverse paths (fiber as one path and air as the other) will easily meet or exceed existing Bellcore availability standards for SONET rings. The hybrid part-fiber, part-air ring advantageously protects customers from fiber cuts (a.k.a. `backhoe fade') and may be preferable to over service via either an unprotected fiber spur or over a `collapsed' fiber ring made up of fiber segments sharing a common conduit. The experiment is performed at an OC-12 (622 Mbps) data rate in a point-to-consecutive point configuration which demonstrates the use of a relay site to work-around a line- of-sight obstruction.

  8. Optical fiber having wave-guiding rings

    DOEpatents

    Messerly, Michael J.; Dawson, Jay W.; Beach, Raymond J.; Barty, Christopher P. J.

    2011-03-15

    A waveguide includes a cladding region that has a refractive index that is substantially uniform and surrounds a wave-guiding region that has an average index that is close to the index of the cladding. The wave-guiding region also contains a thin ring or series of rings that have an index or indices that differ significantly from the index of the cladding. The ring or rings enable the structure to guide light.

  9. An Instability in Narrow Planetary Rings

    NASA Astrophysics Data System (ADS)

    Weiss, J. W.; Stewart, G. R.

    2003-08-01

    We will present our work investigating the behavior of narrow planetary rings with low dispersion velocities. Such narrow a ring will be initially unstable to self-gravitational collapse. After the collapse, the ring is collisionally very dense. At this stage, it is subject to a new instability. Waves appear on the inner and outer edges of the ring within half of an orbital period. The ring then breaks apart radially, taking approximately a quarter of an orbital period of do so. As clumps of ring particles expand radially away from the dense ring, Kepler shear causes these clumps to stretch out azimuthally, and eventually collapse into a new set of dense rings. Small-scale repetitions of the original instability in these new rings eventually leads to a stabilized broad ring with higher dispersion velocities than the initial ring. Preliminary results indicate that this instability may be operating on small scales in broad rings in the wake-like features seen by Salo and others. Some intriguing properties have been observed during this instability. The most significant is a coherence in the epicyclic phases of the particles. Both self-gravity and collisions in the ring operated to create and enforce this coherence. The coherence might also be responsible for the instability to radial expansion. We also observe that guiding centers of the particles do not migrate to the center of the ring during the collapse phase of the ring. In fact, guiding centers move radially away from the core of the ring during this phase, consistent with global conservation of angular momentum. We will show the results of our simulations to date, including movies of the evolution of various parameters. (Audiences members wanting popcorn are advised to bring their own.) This work is supported by a NASA Graduate Student Research Program grant and by the Cassini mission.

  10. Random Implantation of Asymmetric Intracorneal Rings

    PubMed Central

    Peris-Martínez, Cristina; Gregori Gisbert, Irene

    2014-01-01

    Intracorneal ring employment for treating ectasia is widespread. Although the mechanism of action of intracorneal rings in the regularization of the corneal surface after its implantation is well known in most cases, there are still many doubts. We present a case of implanted intracorneal rings, where, despite the peculiar position of the rings, the patient gains lines of visual acuity and keratoconus remains stable. PMID:24711941

  11. Measuring Gaps In O-Ring Seals

    NASA Technical Reports Server (NTRS)

    Johnson, Scott E.

    1990-01-01

    Technique enables measurement of leakage areas created by small obstructions in O-ring seals. With simple fixture, gaps measured directly. Compresses piece of O-ring by amount determined by spacers. Camera aimed through clear plastic top plate records depression made in O-ring by obstruction. Faster, easier, more accurate than conventional estimation.

  12. 21 CFR 872.5550 - Teething ring.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DENTAL DEVICES Therapeutic Devices § 872.5550 Teething ring. (a) Identification. A teething ring is a...) Classification. Class I if the teething ring does not contain a fluid, such as water. The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter. (2) Class II if...

  13. Ring Equinox Temperature Variations from Cassini CIRS

    NASA Astrophysics Data System (ADS)

    Spilker, Linda J.; Ferrari, C.; Morishima, R.; Flandes, A.; Altobelli, N.; Leyrat, C.; Pilorz, S.; Edgington, S.

    2010-10-01

    Cassini's Composite infrared spectrometer (CIRS) retrieved the temperatures of Saturn's main rings at equinox as the sun traversed from the south to north side of the rings. At equinox the solar input is very small and the primary heat sources for the rings are Saturn thermal and visible energy. The main rings cooled to their lowest temperatures measured to date. The ring temperatures at equinox were: C ring, 55-75 K; B ring, 45-60 K; Cassini Division, 45 - 58 K; and A ring, 43 - 52 K. The equinox geometry is unique because Saturn heating dominates, contrasted to earlier in the mission when the primary heat source is light from the sun. Equinox temperatures are almost identical for similar geometries on the north and south sides of the main rings. Overall, the temperatures decrease with increasing distance from the planet as expected but each ring displays a slightly different behavior. For the C ring the temperature varies slightly with the Saturn local time on the particle while the temperature for the densest part of the B ring does not vary with changing geometry. Equinox results will be presented. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA and at CEA Saclay supported by the CNES and CEA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

  14. A Ring Construction Using Finite Directed Graphs

    ERIC Educational Resources Information Center

    Bardzell, Michael

    2012-01-01

    In this paper we discuss an interesting class of noncommutative rings which can be constructed using finite directed graphs. This construction also creates a vector space. These structures provide undergraduate students connections between ring theory and graph theory and, among other things, allow them to see a ring unity element that looks quite…

  15. Stable bound orbits around black rings

    SciTech Connect

    Igata, Takahisa; Ishihara, Hideki; Takamori, Yohsuke

    2010-11-15

    We examine bound orbits of particles around singly rotating black rings. We show that there exist stable bound orbits in toroidal spiral shape near the 'axis' of the ring, and also stable circular orbits on the axis as special cases. The stable bound orbits can have arbitrary large size if the thickness of the ring is less than a critical value.

  16. Rings of uranus: invisible and impossible?

    PubMed

    VAN Flandern, T C

    1979-06-01

    Neither the dynamical nor the optical properties of the rings of Uranus are easily understood, unless it is assumed that they are not rings in the ordinary sense but simply volatile material in the orbits of several individual small satellites. It is possible that other natural satellites may also leave such rings in their wakes.

  17. O-ring gasket test fixture

    NASA Technical Reports Server (NTRS)

    Turner, James Eric (Inventor); Mccluney, Donald Scott (Inventor)

    1991-01-01

    An apparatus is presented for testing O-ring gaskets under a variety of temperature, pressure, and dynamic loading conditions. Specifically, this apparatus has the ability to simulate a dynamic loading condition where the sealing surface in contact with the O-ring moves both away from and axially along the face of the O-ring.

  18. Improved piston rings for a stirling engine

    NASA Technical Reports Server (NTRS)

    Mcdougal, A. R.

    1980-01-01

    Cast-iron piston rings coated with commercially-available antifriction materials improves cylinder life of high-performance Stirling engine. Ring is efficient heat conductor between piston and cylinder. Device has low thermal expansion which maintains minimum gap in ring, good radial force characteristics, and essentially indefinite life.

  19. The Promise of Intravaginal Rings for Prevention: User Perceptions of Biomechanical Properties and Implications for Prevention Product Development

    PubMed Central

    Kiser, Patrick F.; Buckheit, Karen; Bregman, Dana; Thompson, Lara; Jensen, Kathleen; Johnson, Todd; Buckheit, Robert W.

    2015-01-01

    Intravaginal rings (IVRs) are currently under investigation as devices for the delivery of agents to protect against the sexual transmission of HIV and STIs, as well as pregnancy. To assist product developers in creating highly acceptable rings, we sought to identify characteristics that intravaginal ring users consider when making decisions about ring use or non-use. We conducted four semi-structured focus groups with 21 women (aged 18–45) who reported using an IVR in the past 12 months. Participants manipulated four prototype rings in their hands, discussed ring materials, dimensionality, and “behavior,” and shared perceptions and appraisals. Five salient ring characteristics were identified: 1) appearance of the rings’ surfaces, 2) tactile sensations of the cylinder material, 3) materials properties, 4) diameter of the cylinder, and 5) ring circumference. Pliability (or flexibility) was generally considered the most important mechanical property. Several ring properties (e.g., porousness, dimensionality) were associated with perceptions of efficacy. Women also revealed user behaviors that may impact the effectiveness of certain drugs, such as removing, rinsing and re-inserting the ring while bathing, and removing the ring during sexual encounters. As product developers explore IVRs as prevention delivery systems, it is critical to balance product materials and dimensions with use parameters to optimize drug delivery and the user experience. It is also critical to consider how user behaviors (e.g., removing the ring) might impact drug delivery. PMID:26695431

  20. Drag of buoyant vortex rings

    NASA Astrophysics Data System (ADS)

    Vasel-Be-Hagh, Ahmadreza; Carriveau, Rupp; Ting, David S.-K.; Turner, John Stewart

    2015-10-01

    Extending from the model proposed by Vasel-Be-Hagh et al. [J. Fluid Mech. 769, 522 (2015), 10.1017/jfm.2015.126], a perturbation analysis is performed to modify Turner's radius by taking into account the viscous effect. The modified radius includes two terms; the zeroth-order solution representing the effect of buoyancy, and the first-order perturbation correction describing the influence of viscosity. The zeroth-order solution is explicit Turner's radius; the first-order perturbation modification, however, includes the drag coefficient, which is unknown and of interest. Fitting the photographically measured radius into the modified equation yields the time history of the drag coefficient of the corresponding buoyant vortex ring. To give further clarification, the proposed model is applied to calculate the drag coefficient of a buoyant vortex ring at a Bond number of approximately 85; a similar procedure can be applied at other Bond numbers.

  1. Fiber Ring Optical Gyroscope (FROG)

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The design, construction, and testing of a one meter diameter fiber ring optical gyro, using 1.57 kilometers of single mode fiber, are described. The various noise components: electronic, thermal, mechanical, and optical, were evaluated. Both dc and ac methods were used. An attempt was made to measure the Earth rotation rate; however, the results were questionable because of the optical and electronic noise present. It was concluded that fiber ring optical gyroscopes using all discrete components have many serious problems that can only be overcome by discarding the discrete approach and adapting an all integrated optic technique that has the laser source, modulator, detector, beamsplitters, and bias element on a single chip.

  2. Drag of buoyant vortex rings.

    PubMed

    Vasel-Be-Hagh, Ahmadreza; Carriveau, Rupp; Ting, David S-K; Turner, John Stewart

    2015-10-01

    Extending from the model proposed by Vasel-Be-Hagh et al. [J. Fluid Mech. 769, 522 (2015)], a perturbation analysis is performed to modify Turner's radius by taking into account the viscous effect. The modified radius includes two terms; the zeroth-order solution representing the effect of buoyancy, and the first-order perturbation correction describing the influence of viscosity. The zeroth-order solution is explicit Turner's radius; the first-order perturbation modification, however, includes the drag coefficient, which is unknown and of interest. Fitting the photographically measured radius into the modified equation yields the time history of the drag coefficient of the corresponding buoyant vortex ring. To give further clarification, the proposed model is applied to calculate the drag coefficient of a buoyant vortex ring at a Bond number of approximately 85; a similar procedure can be applied at other Bond numbers.

  3. Behavioral Mapless Navigation Using Rings

    NASA Technical Reports Server (NTRS)

    Monroe, Randall P.; Miller, Samuel A.; Bradley, Arthur T.

    2012-01-01

    This paper presents work on the development and implementation of a novel approach to robotic navigation. In this system, map-building and localization for obstacle avoidance are discarded in favor of moment-by-moment behavioral processing of the sonar sensor data. To accomplish this, we developed a network of behaviors that communicate through the passing of rings, data structures that are similar in form to the sonar data itself and express the decisions of each behavior. Through the use of these rings, behaviors can moderate each other, conflicting impulses can be mediated, and designers can easily connect modules to create complex emergent navigational techniques. We discuss the development of a number of these modules and their successful use as a navigation system in the Trinity omnidirectional robot.

  4. APS storage ring vacuum system

    SciTech Connect

    Niemann, R.C.; Benaroya, R.; Choi, M.; Dortwegt, R.J.; Goeppner, G.A.; Gonczy, J.; Krieger, C.; Howell, J.; Nielsen, R.W.; Roop, B.; Wehrle, R.B.

    1990-01-01

    The Advanced Photon Source synchrotron radiation facility, under construction at the Argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's experimental program. The Storage Ring's 1104 m circumference is divided into 40 functional sectors. The sectors include vacuum, beam transport, control, acceleration and insertion device components. The vacuum system, which is designed to operate at a pressure of 1 n Torr, consists of 240 connected sections, the majority of which are fabricated from an aluminum alloy extrusion. The sections are equipped with distributed NeG pumping, photon absorbers with lumped pumping, beam position monitors, vacuum diagnostics and valving. The details of the vacuum system design, selected results of the development program and general construction plans are presented. 11 refs., 6 figs., 3 tabs.

  5. The Distracting Effects of a Ringing Cell Phone: An Investigation of the Laboratory and the Classroom Setting

    PubMed Central

    Shelton, Jill T.; Elliott, Emily M.; Lynn, Sharon D.; Exner, Amanda L.

    2010-01-01

    The detrimental effects of a ringing phone on cognitive performance were investigated in four experiments. In Experiments 1 and 2, the effects of different types of sounds (a standard cell phone ring, irrelevant tones and an instrumental song commonly encountered by participants) on performance were examined. In Experiment 1, slower responses were observed in all auditory groups relative to a silence condition, but participants in the ring and song conditions recovered more slowly. In Experiment 2, participants who were warned about the potential for distraction recovered more quickly, suggesting a benefit of this prior knowledge. This investigation continued in a college classroom setting (Experiments 3a and 3b); students were exposed to a ringing cell phone during the lecture. Performance on a surprise quiz revealed low accuracy rates on material presented while the phone was ringing. These findings offer insight into top-down cognitive processes that moderate involuntary orienting responses associated with a common stimulus encountered in the environment. PMID:21234286

  6. Centric rings, acentric rings and excess acentric fragments based on a random-walk interphase chromosome model

    NASA Technical Reports Server (NTRS)

    Wu, H.; Durante, M.; Sachs, R. K.; Yang, T. C.

    1997-01-01

    Excess acentric fragments, consisting of acentric rings and acentric linear fragments, are among the most frequent kinds of chromosome-type aberrations produced by radiation. The frequency of acentric rings cannot be obtained directly by experiment but is estimated here from the ratio of acentric to centric rings, evaluated using a random-walk model for the organization of chromatin during interphase and an assumption that the probability of an exchange formation is proportional to the rate of collision between two DSB. This ratio is calculated to be 2.5 in low-LET irradiated human fibroblasts, significantly greater than the ratio if proximity effects are not considered. The calculated frequency of acentric rings is insufficient to account for all the observed excess acentric fragments. Assuming that the rest of the excess acentric fragments are due to incomplete exchanges, all possible recombinations between two DSB that result in acentric rings and acentric linear fragments have been identified. From the chromosome aberration data, the incompleteness parameter has been estimated. Intra-arm chromosome exchanges, either complete or incomplete, were estimated to account for more than 50% of the excess acentric fragments in human fibroblasts.

  7. A study on the development of loading device of photoelastic stress freezing method for O-ring stress analysis

    NASA Astrophysics Data System (ADS)

    Hawong, Jai-Sug; Nam, Jeong-Hwan; Han, Song-Ling; Kwon, O.-Sung; Park, Sung-Han

    2008-11-01

    There are O-rings for movement and for airtight in O-rings. O-ring for movement is used to protect to penetrate the dust or the alien substance into cylinder. O-ring for airtight is used to maintain airtight. Airtight of O-ring is controlled by squeeze rate and the gap between external diameter of groove and internal diameter of cylinder. Squeeze rate of O-ring is controlled by internal diameter of groove. Gap between external diameter of groove and internal diameter of cylinder is controlled by the external diameter of groove. Stresses of O-ring are depended on the squeeze rate, gap and internal pressure. O-ring for airtight is under uniform squeeze rate and internal pressure with constant gap. And then stress distributions are very complicated. Therefore stresses of O-ring are almost analyzed by experiment. To study the stress distributions of O-ring by experiment, 3-dimensional photoelastic experiment had better be used. To study stress distributions of O-ring by 3-dimensional photoelastic experiment, loading device is very important. Loading device should are functions, which uniform squeeze rate and internal pressure etc, can be applied, and the uniform squeeze rate can be controlled. Therefore, in this research, the loading device with functions explained above was developed. The validity of the loading device was confirmed by the stress distributions of O-ring, the configuration change of O-ring and the contact length of O-ring etc.. When squeeze rate is constant, the contact length of upper of the deformed O-ring is almost equal to that of lower of the deformed O-ring. When the internal pressure is applied to O-ring under uniform squeeze rate, the contact length of upper of O-ring is increased with the increment of the internal pressure by little. The contact length of lower of O-ring is constant irrespective of the increment of the internal pressure.

  8. The Friction of Piston Rings

    NASA Technical Reports Server (NTRS)

    Tischbein, Hans W

    1945-01-01

    The coefficient of friction between piston ring and cylinder liner was measured in relation to gliding acceleration, pressure, temperature, quantity of oil and quality of oil. Comparing former lubrication-technical tests, conclusions were drawn as to the state of friction. The coefficients of friction as figured out according to the hydrodynamic theory were compared with those measured by tests. Special tests were made on "oiliness." The highest permissible pressure was measured and the ratio of pressure discussed.

  9. Ball-joint grounding ring

    NASA Technical Reports Server (NTRS)

    Aperlo, P. J. A.; Buck, P. A.; Weldon, V. A.

    1981-01-01

    In ball and socket joint where electrical insulator such as polytetrafluoroethylene is used as line to minimize friction, good electrical contact across joint may be needed for lightning protection or to prevent static-charge build-up. Electrical contact is maintained by ring of spring-loaded fingers mounted in socket. It may be useful in industry for cranes, trailers, and other applications requiring ball and socket joint.

  10. Sweden's Siljan ring well evaluated

    SciTech Connect

    Gold, T.

    1991-01-14

    The final results are in from the first major drilling operation undertaken to explore the deeper levels of the Siljan ring impactor crater in Central Sweden. The results demonstrate that hydrocarbon gases from methane to pentane-as well as a light, largely saturated oil-are present deep in the granitic rock. The impact crater, generated 360 million year ago by a major meteorite, is now a circular area about 44 km across.

  11. Spontaneous currents in mesoscopic rings

    SciTech Connect

    Wohleben, D.; Freche, P.; Esser, M. ); Zipper, E.; Szopa, M. )

    1992-10-20

    In this paper, in a system of mesoscopic rings, the influence of orbital magnetic interaction between the electrons is investigated. At a critical temperature T[sub c] the system undergoes a phase transition into a current carrying state. T[sub c] depends strongly on geometry of the system and/or its Fermi-surface, and on the quantum size gap at the Fermi level. Elastic scattering reduces T[sub c] and eventually suppresses the transition.

  12. Lattice of the NICA Collider Rings

    SciTech Connect

    Sidorin, Anatoly; Kozlov, Oleg; Meshkov, Igor; Mikhaylov, Vladimir; Trubnikov, Grigoriy; Lebedev, Valeri Nagaitsev, Sergei; Senichev, Yurij; /Julich, Forschungszentrum

    2010-05-01

    The Nuclotron-based Ion Collider fAcility (NICA) is a new accelerator complex being constructed at JINR. It is designed for collider experiments with ions and protons and has to provide ion-ion (Au{sup 79+}) and ion-proton collisions in the energy range 1 {divided_by} 4.5 GeV/n and collisions of polarized proton-proton and deuteron-deuteron beams. Collider conceptions with constant {gamma}{sub tr} and with possibility of its variation are considered. The ring has the racetrack shape with two arcs and two long straight sections. Its circumference is about 450m. The straight sections are optimized to have {beta}* {approx} 35cm in two IPs and a possibility of final betatron tune adjustment.

  13. Accelerator physics measurements at the damping ring

    NASA Astrophysics Data System (ADS)

    Rivkin, L.; Delahaye, J. P.; Wille, K.; Allen, M. A.; Bane, K.; Fieguth, T.; Hofmann, A.; Button, A.; Lee, M.; Linebarger, W.

    1985-05-01

    Besides the optics measurements described elsewhere, machine experiments were done at the Stanford Linear Collider (SLC) damping ring to determine some of its parameters. The synchrotron radiation energy loss which gives the damping rates was measured by observing the RF-voltage dependence of the synchronous phase angle. The emittance was obtained from the synchrotron light monitor, scraper measurements and by extracting the beam through a doublet and measuring its size for different quadrupole settings. Current dependent effects such as parasitic mode losses, head tail instabilities, synchrotron and betatron frequency shifts were measured to estimate the impedance. RF-cavity beam loading and its compensation were also studied and ion collection was investigated. All results agree reasonably well with expectations and indicate no limitations to the design performance.

  14. Gibbs Ringing in Diffusion MRI

    PubMed Central

    Veraart, Jelle; Fieremans, Els; Jelescu, Ileana O.; Knoll, Florian; Novikov, Dmitry S.

    2016-01-01

    Purpose To study and reduce the effect of Gibbs ringing artifact on computed diffusion parameters. Methods We reduce the ringing by extrapolating the k-space of each diffusion weighted image beyond the measured part by selecting an adequate regularization term. We evaluate several regularization terms and tune the regularization parameter to find the best compromise between anatomical accuracy of the reconstructed image and suppression of the Gibbs artifact. Results We demonstrate empirically and analytically that the Gibbs artifact, which is typically observed near sharp edges in magnetic resonance images, has a significant impact on the quantification of diffusion model parameters, even for infinitesimal diffusion weighting. We find the second order total generalized variation to be a good choice for the penalty term to regularize the extrapolation of the k-space, as it provides a parsimonious representation of images, a practically full suppression of Gibbs ringing, and the absence of staircasing artifacts typical for total variation methods. Conclusions Regularized extrapolation of the k-space data significantly reduces truncation artifacts without compromising spatial resolution in comparison to the default option of window filtering. In particular, accuracy of estimating diffusion tensor imaging and diffusion kurtosis imaging parameters improves so much that unconstrained fits become possible. PMID:26257388

  15. The Rings of Chariklo under Close Encounters with the Giant Planets

    NASA Astrophysics Data System (ADS)

    Araujo, R. A. N.; Sfair, R.; Winter, O. C.

    2016-06-01

    The Centaur population is composed of minor bodies wandering between the giant planets that frequently perform close gravitational encounters with these planets, leading to a chaotic orbital evolution. Recently, the discovery of two well-defined narrow rings was announced around the Centaur 10199 Chariklo. The rings are assumed to be in the equatorial plane of Chariklo and to have circular orbits. The existence of a well-defined system of rings around a body in such a perturbed orbital region poses an interesting new problem. Are the rings of Chariklo stable when perturbed by close gravitational encounters with the giant planets? Our approach to address this question consisted of forward and backward numerical simulations of 729 clones of Chariklo, with similar initial orbits, for a period of 100 Myr. We found, on average, that each clone experiences during its lifetime more than 150 close encounters with the giant planets within one Hill radius of the planet in question. We identified some extreme close encounters that were able to significantly disrupt or disturb the rings of Chariklo. About 3% of the clones lose their rings and about 4% of the clones have their rings significantly disturbed. Therefore, our results show that in most cases (more than 90%), the close encounters with the giant planets do not affect the stability of the rings in Chariklo-like systems. Thus, if there is an efficient mechanism that creates the rings, then these structures may be common among these kinds of Centaurs.

  16. Interaction of Vortex Rings and Steady Jets with Permeable Screens of Varied Porosity

    NASA Astrophysics Data System (ADS)

    Musta, Mustafa

    2013-11-01

    Vortex ring and steady jet interaction with a porous matrix formed from several parallel, transparent permeable screens with the same grid geometry for open area ratios (φ) 49.5% - 83.8% was studied previously using digital particle image velocimetry (DPIV) at jet Reynolds number (Re) of 1000-3000. Vortex ring results showed that unlike the experiments with thin screens, a transmitted vortex ring, which has a similar diameter to the primary one, wasn't formed. Instead a centerline vortex ring like structure formed and its diameter, circulation, and dissipation time decreased as φ decreased. However, for the case of screens φ = 55.7% with large screen spacing, reformation of large scale weak vortex rings was observed downstream of the first screen. The present work experimentally investigates the interaction of vortex rings and steady jets with screens of decreasing φ (83.8%-49.5%) in the flow direction. A piston type vortex ring generator was used and measurements were made using DPIV. The vortex ring results show that the size and circulation of the vortex ring like flow structure was changed based on the screen φ within the permeable screen matrix. Similarly, steady jet flow structure and the local turbulent kinetic energy was changed based on the local screen φ.

  17. Beam Measurements in Storage Rings

    NASA Astrophysics Data System (ADS)

    Hofmann, Albert

    1996-05-01

    Beam measurements in storage rings are made to diagnose performance limitations and to gain knowledge of the beam behavior in view of improvements and to the benefit for other machines. In beam optics the measurement of the orbit or the trajectory with beam position monitors distributed around the ring reveals deflection errors. The overall focusing is checked by measuring the betatron frequency (tune) using a pulse or continuous excitation of the oscillation. Observing this oscillation with all the beam position monitors around the ring the beta function and the betatron phase advance are obtained. This measurement done for different momenta, i.e. RF-frequencies, gives the local chromaticity and its correction. The tune dependence on quadrupole strength gives the value of the local beta function. Synchrotron radiation is a powerful diagnostics tool and can give the beam cross section. Beam instabilities are investigated with similar methods. The growth or damping rates and frequencies of betatron and synchrotron oscillations, observed as a function of intensity, give a convolution of the resistive and reactive part of the transverse and longitudinal impedance with the spectrum of the oscillation mode. Coupled bunch instabilities are caused by narrow band impedances at particular frequencies while single traversal effects, including energy loss and bunch lengthening, are due to a broad band impedance. A model of the impedance can be constructed from such measurements done with different bunch lengths, tunes and other parameters. In some cases the element causing an instability can be identified. The dependence of the orbit and phase advance around the ring on intensity can give the location of impedances. To probe the impedance at very high frequencies the effects on very short bunches or the energy loss of a continuous beam due to its Schottky noise are measured. The beam energy, usually known from magnetic measurements, can be obtained directly with high

  18. The making of ring currents.

    PubMed

    Monaco, Guglielmo; Zanasi, Riccardo

    2016-04-28

    Benzene, planar cyclooctatetraene, and borazine have been taken into account as archetypal aromatic, anti-aromatic, and non-aromatic systems. Then, the making of the π-electron diatropic ring current of benzene, huge paratropic ring current of planar cyclooctatetraene, and weak diatropic ring current of borazine, has been monitored by means of DFT calculations of current density maps and bond current strengths along a concerted, highly symmetric reaction pathway for the trimerization and tetramerization of acetylene to benzene and planar cyclooctatetraene and the trimerization of the simplest iminoborane (BH2N) to borazine. Besides, a simple model is presented that permits to infer the presence of a ring current only on account of the sum of homotropic local vortices. The model works satisfactorily for borazine and surely as well for benzene with a substantial difference. On the one hand, for borazine, the evolution of the current density along the formation reaction can be recast summing three virtually unchanged diatropic current loops with respect to parent iminoborane molecules. On the other hand, the benzene ring current is an emerging property that can be re-elaborated as the sum of three diatropic current loops of increased diatropicity with respect to parent acetylene molecules, i.e., the radius of the maximum current increases form 0.76 to 0.97 Å and the current strength increases from 3.6 to 6.7 nA T(-1). In these terms, the difference between the aromatic benzene and non-aromatic borazine can be understood as the attitude of the acetylene molecules to form always wider and stronger current loops as they get closer, a behavior not shared by the iminoborane molecules. For planar cyclooctatetraene, the paratropic circulation arising from the HOMO-LUMO transition makes the model inapplicable, since the initial hypothesis of homotropic circulations over the reaction coordinate is violated. In a sense, the fact that the model works only for a bit of the

  19. Wavelength-tunable optical ring resonators

    DOEpatents

    Watts, Michael R.; Trotter, Douglas C.; Young, Ralph W.; Nielson, Gregory N.

    2009-11-10

    Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

  20. Wavelength-tunable optical ring resonators

    DOEpatents

    Watts, Michael R.; Trotter, Douglas C.; Young, Ralph W.; Nielson, Gregory N.

    2011-07-19

    Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

  1. Modeling equinox temperature variations in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Spilker, L. J.; Ferrari, C. C.; Morishima, R.

    2011-12-01

    For a few days around Saturn ring equinox, the Cassini Composite Infrared Spectrometer (CIRS) obtained data on Saturn's rings at different local times and phase angles. We examine results from 15 scans taken near equinox. The sun was shining on the south side of the rings prior to the equinox crossing. The solar elevation angle in the 15 scans varied between -0.00007 degrees and 0.036 degrees and the phase angle ranged from 30 degrees to 147 degrees. The equinox geometry is unique because the sun is edge-on to the rings. Saturn heating dominates while solar heating is at a minimum. The ring temperature varies between the lit and unlit sides of the A and B rings when the sun is the dominant heat source. With the sun shining on the rings the temperature of the lit rings decreases with increasing phase angle and the ring temperature in the shadow is less than the ring temperature at noon. At equinox the ring temperature does not decrease with increasing phase angle and the temperature at noon is no longer greater than the temperature in the shadow. As the solar elevation angle decreased the last few degrees, the ring temperatures on the lit and unlit sides rapidly decreased to the coldest temperatures observed thus far. At equinox radial and longitudinal temperature variations are observed in the A, B and C rings and the Cassini Division. The radial temperature variations result both from the decreasing Saturn solid angle with increasing distance from the planet and varying optical depth as the screening effect of optically thicker rings limits the heat contribution to primarily one hemisphere of Saturn. Both monolayer and multilayer models can explain the radial variations in ring temperature except for the A ring. A ring model fits produce temperatures that are lower than observed temperatures perhaps because of the effects from gravitational wakes, density waves and bending waves that are not included in the models. Saturn ring temperatures near equinox also vary

  2. Fluorescent hydroxyl emissions from Saturn's ring atmosphere.

    PubMed

    Hall, D T; Feldman, P D; Holberg, J B; McGrath, M A

    1996-04-26

    Just before earth passed through Saturn's ring plane on 10 August 1995, the Hubble Space Telescope Faint Object Spectrograph detected ultraviolet fluorescent emissions from a tenuous atmosphere of OH molecules enveloping the rings. Brightnesses decrease with increasing distance above the rings, implying a scale height of about 0.45 Saturn radii (Rs). A spatial scan 0.28Rs above the A and B rings indicates OH column densities of about 10(13) cm(-2) and number densities of up to 700 cm(-3). Saturn's rings must produce roughly 10(25) to 10(29) OH molecules per second to maintain the observed OH distribution.

  3. Oxygen ions observed near Saturn's A ring.

    PubMed

    Waite, J H; Cravens, T E; Ip, W-H; Kasprzak, W T; Luhmann, J G; McNutt, R L; Niemann, H B; Yelle, R V; Mueller-Wodarg, I; Ledvina, S A; Scherer, S

    2005-02-25

    Ions were detected in the vicinity of Saturn's A ring by the Ion and Neutral Mass Spectrometer (INMS) instrument onboard the Cassini Orbiter during the spacecraft's passage over the rings. The INMS saw signatures of molecular and atomic oxygen ions and of protons, thus demonstrating the existence of an ionosphere associated with the A ring. A likely explanation for these ions is photoionization by solar ultraviolet radiation of neutral O2 molecules associated with a tenuous ring atmosphere. INMS neutral measurements made during the ring encounter are dominated by a background signal.

  4. Piston ring designs for reduced friction

    SciTech Connect

    Hill, S.H.; Newman, B.A.

    1984-01-01

    To reduce parasitic losses, a project was initiated to design, develop and bring to production a piston ring set which reduces engine friction while maintaining ring performance. In this paper, theoretical considerations affecting piston ring friction, and their implication in ring design, are discussed. An estimate of friction reduction and fuel economy improvement which can be achieved is calculated. Features of the resulting designs are reviewed, and friction, dynamometer, and vehicle test results are presented. Future ring design changes for reduced friction are reviewed.

  5. Signal and power roll ring testing update

    NASA Technical Reports Server (NTRS)

    Smith, Dennis W.

    1989-01-01

    The development of the roll ring as a long-life, low-torque alternative to the slip ring is discussed. A roll ring consists of one or more circular flexures captured by their own spring force in the annular space between two concentric conductors or contact rings. The advantages of roll rings over other types of electrical transfer devices are: extremely low drag torque, high transfer efficiencies in high-power configurations, extremely low wear debris generation, long life, and low weight for high-power applications.

  6. Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Baker, D. N.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.; Larsen, B. A.; Skoug, R. M.; Funsten, H. O.; Friedel, R. H. W.; Reeves, G. D.; Spence, H. E.; Mitchell, D. G.; Lanzerotti, L. J.

    2016-04-01

    Based on comprehensive measurements from Helium, Oxygen, Proton, and Electron Mass Spectrometer Ion Spectrometer, Relativistic Electron-Proton Telescope, and Radiation Belt Storm Probes Ion Composition Experiment instruments on the Van Allen Probes, comparative studies of ring current electrons and ions are performed and the role of energetic electrons in the ring current dynamics is investigated. The deep injections of tens to hundreds of keV electrons and tens of keV protons into the inner magnetosphere occur frequently; after the injections the electrons decay slowly in the inner belt but protons in the low L region decay very fast. Intriguing similarities between lower energy protons and higher-energy electrons are also found. The evolution of ring current electron and ion energy densities and energy content are examined in detail during two geomagnetic storms, one moderate and one intense. The results show that the contribution of ring current electrons to the ring current energy content is much smaller than that of ring current ions (up to ~12% for the moderate storm and ~7% for the intense storm), and <35 keV electrons dominate the ring current electron energy content at the storm main phases. Though the electron energy content is usually much smaller than that of ions, the enhancement of ring current electron energy content during the moderate storm can get to ~30% of that of ring current ions, indicating a more dynamic feature of ring current electrons and important role of electrons in the ring current buildup. The ring current electron energy density is also shown to be higher at midnight and dawn while lower at noon and dusk.

  7. Nuclear Rings in Galaxies - A Kinematic Perspective

    NASA Technical Reports Server (NTRS)

    Mazzuca, Lisa M.; Swaters, Robert A.; Knapen, Johan H.; Veilleux, Sylvain

    2011-01-01

    We combine DensePak integral field unit and TAURUS Fabry-Perot observations of 13 nuclear rings to show an interconnection between the kinematic properties of the rings and their resonant origin. The nuclear rings have regular and symmetric kinematics, and lack strong non-circular motions. This symmetry, coupled with a direct relationship between the position angles and ellipticities of the rings and those of their host galaxies, indicate the rings are in the same plane as the disc and are circular. From the rotation curves derived, we have estimated the compactness (v(sup 2)/r) up to the turnover radius, which is where the nuclear rings reside. We find that there is evidence of a correlation between compactness and ring width and size. Radially wide rings are less compact, and thus have lower mass concentration. The compactness increases as the ring width decreases. We also find that the nuclear ring size is dependent on the bar strength, with weaker bars allowing rings of any size to form.

  8. Leapfrogging of multiple coaxial viscous vortex rings

    SciTech Connect

    Cheng, M. Lou, J.; Lim, T. T.

    2015-03-15

    A recent theoretical study [Borisov, Kilin, and Mamaev, “The dynamics of vortex rings: Leapfrogging, choreographies and the stability problem,” Regular Chaotic Dyn. 18, 33 (2013); Borisov et al., “The dynamics of vortex rings: Leapfrogging in an ideal and viscous fluid,” Fluid Dyn. Res. 46, 031415 (2014)] shows that when three coaxial vortex rings travel in the same direction in an incompressible ideal fluid, each of the vortex rings alternately slips through (or leapfrogs) the other two ahead. Here, we use a lattice Boltzmann method to simulate viscous vortex rings with an identical initial circulation, radius, and separation distance with the aim of studying how viscous effect influences the outcomes of the leapfrogging process. For the case of two identical vortex rings, our computation shows that leapfrogging can be achieved only under certain favorable conditions, which depend on Reynolds number, vortex core size, and initial separation distance between the two rings. For the case of three coaxial vortex rings, the result differs from the inviscid model and shows that the second vortex ring always slips through the leading ring first, followed by the third ring slipping through the other two ahead. A simple physical model is proposed to explain the observed behavior.

  9. Double acting stirling engine piston ring

    SciTech Connect

    Howarth, R.B.

    1986-04-15

    A pressure balanced piston ring is described for limiting the leakage of a high pressure region on one side of the piston ring to a region of low pressure on the opposite side of the piston ring along a cylinder wall. The piston ring apparatus consists of: a piston ring of low elastic modulus material maintained in a circumferential groove in the reciprocating piston; two elastomeric seals, positioned on opposite axial sides of the piston ring so as to isolate an inner surface from the high and low pressure regions; means for balancing the pressure on the inner surface of the piston ring with the average pressure in a leak path between the piston ring and the cylinder wall, thereby rendering friction and wear of the piston ring independent of the high and low pressures; and means for exerting a predetermined force on the piston ring to maintain contact with the cylinder wall and control the friction between the piston ring and the cylinder wall and leakage between the high and low pressure regions.

  10. Multi-wavelength Studies Of Saturn's Rings To Constrain Ring Particle Properties And Ring Structure

    NASA Astrophysics Data System (ADS)

    Spilker, Linda J.; Deau, E.; Morishima, R.; Filacchione, G.; Hedman, M. M.; Nicholson, P.; Bradley, T.; Colwell, J.

    2012-10-01

    The characteristics of Saturn’s ring particles and their regoliths are examined by modeling variations in brightness, color, temperature and spectral parameters with changing viewing geometry over a wide range of wavelengths. Data from Cassini CIRS, ISS, VIMS and UVIS scans of the lit and unlit main rings at multiple geometries and solar elevations are used. Using multi-wavelength data sets allows us to test different thermal models by combining effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, and particle spin rate and spin axis orientation. Over a range of solar elevations the CIRS temperature and ISS color variations are confined primarily to phase angle with only small differences from changing spacecraft elevation. Color and temperature dependence with varying solar elevation angle are also observed. Brightness dependence with changing solar elevation angle and phase angle is observed with UVIS. VIMS observations show that IR water ice absorption band depths are a very weak function of phase angle, out to 140 deg phase, suggesting that interparticle light scattering is relatively unimportant except at very high phase angles. These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The temperature and color variation with phase angle may be a result of scattering within the regolith and on possibly rough surfaces of the clumps, as well as a contribution from scattering between individual particles in a many-particle-thick layer. Preliminary results from our joint studies will be presented. This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2012 California Institute of Technology. Government sponsorship is acknowledged.

  11. A search for cold water rings

    NASA Technical Reports Server (NTRS)

    Cheney, R. E.

    1981-01-01

    SAR imagery obtained by Seasat in the Sargasso Sea during 1978 is examined for cold ring signatures. One orbit on August 26 is thought to have imaged the edge of a cold ring, although the ring's position was not well known at the time. During another orbit on September 23, drifting buoy and expendable bathythermography data furnished conclusive evidence that the ring was centered directly in the SAR swath. Although some suggestive patterns are visible in the images, it is not clear that cold rings can be identified by SAR, even though dynamically similar features, such as the Gulf Stream and warm rings, can be accurately detected. The suggestion is made that cold rings may be imaged inadequately because of their lack of surface temperature gradient.

  12. On the Janus-Epimetheus Ring

    NASA Astrophysics Data System (ADS)

    Winter, Othon; Souza, Alexandre; Sfait, Rafael; Giuliatti Winter, Silvia; Mourão, Decio; Foryta, Dietmar

    2016-10-01

    Cassini spacecraft found a new and unique ring to share a trajectory with Janus and Epimetheus, co-orbital satellites of Saturn. Analyzing Cassini images, we found that the Janus-Epimetheus ring is a continuous and smooth ring, which can only be seen by Cassini's camera at very high phase angles, not being observed at other geometries, as a `firefly' behavior. We also found a very short mean lifetime for the ring particles, less than a couple of decades. Consequently, the ring needs to be constantly replenished. Using a collisional model of micrometeoroids on the satellites' surfaces we found that it produces a faint ring that is fully compatible with the Janus-Epimitheus ring. We also verified that the steady state of the generated particles distribution corresponds to that of the light scattering regime responsible for the `firefly' behavior.

  13. Feasibility of a ring FEL at low emittance storage rings

    NASA Astrophysics Data System (ADS)

    Agapov, I.

    2015-09-01

    A scheme for generating coherent radiation at latest generation low emittance storage rings such as PETRA III at DESY (Balewski et al., 2004 [1]) is proposed. The scheme is based on focusing and subsequent defocusing of the electron beam in the longitudinal phase space at the undulator location. The expected performance characteristics are estimated for radiation in the wavelength range of 500-1500 eV. It is shown that the average brightness is increased by several orders of magnitude compared to spontaneous undulator radiation, which can open new perspectives for photon-hungry soft X-ray spectroscopy techniques.

  14. Stirling engine with improved piston ring assembly

    SciTech Connect

    Meijer, R.J.

    1986-10-07

    This patent describes an engine having a reciprocating piston axially stroking within a walled cylinder by a pressure differential acting on opposite axial sides of the piston and an annular piston ring disposed in an annular piston ring groove around the piston for sealing between the piston and the wall of the cylinder to resist leakage past the piston. The improvement described here is in the piston ring. This piston ring is endowed with a flat radially outwardly facing annular axial surface confronting the cylinder wall, temperature responsive means arranged within the groove for coaction with the piston ring to forcefully urge the piston ring radially outwardly when the engine is cold such that the flat radially outwardly facing annular axial surface of the piston ring is urged flat against the cylinder wall but to relax from urging the piston ring outwardly when the engine becomes warm. The piston ring groove has two contiguous axial portions one of which extends radially deeper into the piston than the other, the piston ring being of generally L-shape in cross section so that it has two leg portions consisting of a radially extending leg portion and an axially extending leg portion. The radially extended leg portion is disposed in cooperative association with the one axial portion of the groove and the axially extending leg portion being disposed in cooperative association with the other axial portion of the groove. The temperature responsive means is disposed within the one axial portion of the piston ring groove to be coactive on the radially extending leg portion of the piston ring, and annular sealing means disposed within the groove for sealing between the piston ring and piston to resist leakage between the piston ring and piston.

  15. Einstein Ring in Distant Universe

    NASA Astrophysics Data System (ADS)

    2005-06-01

    Using ESO's Very Large Telescope, Rémi Cabanac and his European colleagues have discovered an amazing cosmic mirage, known to scientists as an Einstein Ring. This cosmic mirage, dubbed FOR J0332-3557, is seen towards the southern constellation Fornax (the Furnace), and is remarkable on at least two counts. First, it is a bright, almost complete Einstein ring. Second, it is the farthest ever found. ESO PR Photo 20a/05 ESO PR Photo 20a/05 Deep Image of a Region in Fornax (FORS/VLT) [Preview - JPEG: 400 x 434 pix - 60k] [Normal - JPEG: 800 x 867 pix - 276k] [Full Res - JPEG: 1859 x 2015 pix - 3.8M] ESO PR Photo 20b/05 ESO PR Photo 20b/05 Zoom-in on the Newly Found Einstein Ring (FORS/VLT) [Preview - JPEG: 400 x 575 pix - 168k] [Normal - JPEG: 630 x 906 pix - 880k] Caption: ESO PR Photo 20a/05 is a composite image taken in two bands (B and R) with VLT/FORS1 of a small portion of the sky (field-of-view 7x7' or 1/15th of the area of the full moon). The faintest object seen in the image has a magnitude 26, that is, it is 100 million times fainter than what can be observed with the unaided eye. The bright elliptical galaxy on the lower-left quadrant is a dwarf galaxy part of a large nearby cluster in the Fornax constellation. As for all deep images of the sky, this field shows a variety of objects, the brightest ponctual sources being stars from our Galaxy. By far the field is dominated by thousands of faint background galaxies the colours of which are related to the age of their dominant stellar population, their dust content and their distance. The newly found Einstein ring is visible in the top right part of the image. ESO PR Photo 20b/05 zooms-in on the position of the newly found cosmic mirage. ESO PR Photo 20c/05 ESO PR Photo 20c/05 Einstein Ring in Distant Universe (FORS/VLT) [Preview - JPEG: 400 x 584 pix - 104k] [Normal - JPEG: 800 x 1168 pix - 292k] [Full Res - JPEG: 1502 x 2192 pix - 684k] Caption of ESO PR Photo 20c/05: The left image is magnified and centred

  16. DESIGN OF VISIBLE DIAGNOSTIC BEAMLINE FOR NSLS2 STORAGE RING

    SciTech Connect

    Cheng, W.; Fernandes, H.; Hseuh, H.; Kosciuk, B.; Krinsky, S.; Singh, O.

    2011-03-28

    A visible synchrotron light monitor (SLM) beam line has been designed at the NSLS2 storage ring, using the bending magnet radiation. A retractable thin absorber will be placed in front of the first mirror to block the central x-rays. The first mirror will reflect the visible light through a vacuum window. The light is guided by three 6-inch diameter mirrors into the experiment hutch. In this paper, we will describe design work on various optical components in the beamline. The ultra high brightness NSLS-II storage ring is under construction at Brookhaven National Laboratory. It will have 3GeV, 500mA electron beam circulating in the 792m ring, with very low emittance (0.9nm.rad horizontal and 8pm.rad vertical). The ring is composed of 30 DBA cells with 15 fold symmetry. Three damping wigglers will be installed in long straight sections 8, 18 and 28 to lower the emittance. While electrons pass through the bending magnet, synchrotron radiation will be generated covering a wide spectrum. There are other insertion devices in the storage ring which will generate shorter wavelength radiation as well. Synchrotron radiation has been widely used as diagnostic tool to measure the transverse and longitudinal profile. Three synchrotron light beam lines dedicated for diagnostics are under design and construction for the NSLS-II storage ring: two x-ray beam lines (pinhole and CRL) with the source points from Cell 22 BM{_}A (first bending in the DBA cell) and Cell22 three-pole wiggler; the third beam line is using visible part of radiation from Cell 30 BM{_}B (second bending magnet from the cell). Our paper focuses on the design of the visible beam line - SLM.

  17. Prevalent Hallucinations during Medical Internships: Phantom Vibration and Ringing Syndromes

    PubMed Central

    Lin, Yu-Hsuan; Lin, Sheng-Hsuan; Li, Peng; Huang, Wei-Lieh; Chen, Ching-Yen

    2013-01-01

    Background Phantom vibration syndrome is a type of hallucination reported among mobile phone users in the general population. Another similar perception, phantom ringing syndrome, has not been previously described in the medical literature. Methods A prospective longitudinal study of 74 medical interns (46 males, 28 females; mean age, 24.8±1.2 years) was conducted using repeated investigations of the prevalence and associated factors of phantom vibration and ringing. The accompanying symptoms of anxiety and depression were evaluated with the Beck Anxiety and Depression Inventories before the internship began, and again at the third, sixth, and twelfth internship months, and two weeks after the internship ended. Results The baseline prevalence of phantom vibration was 78.1%, which increased to 95.9% and 93.2% in the third and sixth internship months. The prevalence returned to 80.8% at the twelfth month and decreased to 50.0% 2 weeks after the internship ended. The baseline prevalence of phantom ringing was 27.4%, which increased to 84.9%, 87.7%, and 86.3% in the third, sixth, and twelfth internship months, respectively. This returned to 54.2% two weeks after the internship ended. The anxiety and depression scores also increased during the internship, and returned to baseline two weeks after the internship. There was no significant correlation between phantom vibration/ringing and symptoms of anxiety or depression. The incidence of both phantom vibration and ringing syndromes significantly increased during the internship, and subsequent recovery. Conclusion This study suggests that phantom vibration and ringing might be entities that are independent of anxiety or depression during evaluation of stress-associated experiences during medical internships. PMID:23762302

  18. Interaction of a vortex ring with a natural convective layer

    NASA Astrophysics Data System (ADS)

    Palacios-Morales, C.; Gelderblom, G.; Solorio, F.; Salinas-Vázquez, M.; Zenit, R.

    2014-08-01

    We study the dynamics of the interaction of a vortex ring with a shear flow, generated by a natural convective layer. Laminar vortex rings were generated in water with a piston-cylinder arrangement. To generate the shear flow, a vertical wall was heated by a thermal bath held at constant temperature to produce a laminar and stable thermal boundary layer with a Grashof number of O(108). Measurements of the two-dimensional velocity field were obtained with a time resolved particle image velocimetry technique. Additionally, a 3D numerical model was used to simulate the experimental conditions. We mainly conducted experiments for the piston stroke L/D0 = 1 and Re of O(1000). The velocity ratio r = Uvi/Ush (where Uvi is the initial vortex velocity and Ush is the maximum velocity of the shear layer) was in the range 2.2 ⩽ r ⩽ 3.6. The results show that as the vortex approaches the shear layer, the ring expands and stretches mainly in the vertical direction and tilts slightly forming an angle between the wall and the ring plane which increases to about 3°. The rate of reduction of circulation is slower at the lower section of the vortex ring indicating that the momentum transport is more significant in this region. Moreover, the vortex circulation at the lower section increases to about 20% compared to the isothermal case. An analysis of the different mechanisms leading to this ring-shear layer interaction is presented and comparisons with reported data are discussed.

  19. Multi-wavelength studies of Saturn's rings to constrain ring particle properties and ring structure

    NASA Astrophysics Data System (ADS)

    Spilker, L.; Deau, E.; Morishima, R.; Filacchione, G.; Hedman, M.; Nicholson, P.; Colwell, J.; Bradley, T.

    2012-04-01

    A great deal can be learned about the nature of Saturn's ring particles and their regoliths by modeling the changes in brightness, color and temperature with changing viewing geometry over a wide range of wavelengths, from ultraviolet through the thermal infrared. Data from Cassini's Composite Infrared Spectrometer (CIRS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS) and Ultraviolet Imaging Spectrograph (UVIS) are jointly being studied using scans of the lit and unlit main rings (A, B, C and Cassini Division) at multiple geometries and solar elevations. Using multi-wavelength data sets allow us to test different thermal models by combining the effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, particle spin rate and spin axis orientation. With the high spatial resolution of the Cassini data it is now possible to analyze these effects at smaller spatial scales and characterize regions such as the C ring plateaus and ringlets, where albedo differences may be present. In the CIRS data, over a range of solar elevations from -23 degrees to -8 degrees, the bulk of the temperature variations are confined primarily to phase angle. Only small temperature differences are observed with changing spacecraft elevation. Similar behavior is seen in the ISS color data. Color and temperature dependence with changing solar elevation angle are also observed. VIMS observations show that the IR ice absorption band depths are (almost) independent of phase angle, out to ~140 deg phase, suggesting that interparticle light scattering is relatively unimportant except at very high phase angles. These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The temperature and color variation with phase angle may be a result of scattering within the regolith and on possibly rough surfaces

  20. Variations in Ring Particle Cooling across Saturn's Rings with Cassini CIRS

    NASA Astrophysics Data System (ADS)

    Brooks, S. M.; Spilker, L. J.; Pilorz, S.; Edgington, S. G.; Déau, E.; Altobelli, N.

    2010-12-01

    Cassini's Composite Infrared Spectrometer has recorded over two million of spectra of Saturn's rings in the far infrared since arriving at Saturn in 2004. CIRS records far infrared radiation between 10 and 600 cm-1 ( 16.7 and 1000 μ {m} ) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn’s rings peaks in this wavelength range. Ring temperatures can be inferred from FP1 data. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and rapidly changing temperatures are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid particles can be expected to have higher thermal inertias. Ferrari et al. (2005) fit thermal inertia values of 5218 {Jm)-2 {K}-1 {s}-1/2 to their B ring data and 6412 {Jm)-2 {K}-1 {s}-1/2 to their C ring data. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The rings’ thermal budget is dominated by its absorption of solar radiation. As a result, ring particles abruptly cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

  1. Geometric phase of atoms in a magnetic storage ring

    SciTech Connect

    Zhang, P.; You, L.

    2006-12-15

    A magnetically trapped atom experiences an adiabatic geometric (Berry's) phase due to changing field direction. We investigate theoretically such an Aharonov-Bohm-like geometric phase for atoms adiabatically moving inside a storage ring as demonstrated in several recent experiments. Our result shows that this phase shift is easily observable in a closed-loop interference experiment, and thus the shift has to be accounted for in the proposed inertial sensing applications. The spread in phase shift due to the atom transverse distribution is quantified through numerical simulations.

  2. HUBBLE REVEALS ULTRAVIOLET GALACTIC RING

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The appearance of a galaxy can depend strongly on the color of the light with which it is viewed. The Hubble Heritage image of NGC 6782 illustrates a pronounced example of this effect. This spiral galaxy, when seen in visible light, exhibits tightly wound spiral arms that give it a pinwheel shape similar to that of many other spirals. However, when the galaxy is viewed in ultraviolet light with NASA's Hubble Space Telescope, its shape is startlingly different. Ultraviolet light has a shorter wavelength than ordinary visible light, and is emitted from stars that are much hotter than the Sun. At ultraviolet wavelengths, which are rendered as blue in the Hubble image, NGC 6782 shows a spectacular, nearly circular bright ring surrounding its nucleus. The ring marks the presence of many recently formed hot stars. Two faint, dusty spiral arms emerge from the outer edge of the blue ring and are seen silhouetted against the golden light of older and fainter stars. A scattering of blue stars at the outer edge of NGC 6782 in the shape of two dim spiral arms shows that some star formation is occurring there too. The inner ring surrounds a small central bulge and a bar of stars, dust, and gas. This ring is itself part of a larger dim bar that ends in these two outer spiral arms. Astronomers are trying to understand the relationship between the star formation seen in the ultraviolet light and how the bars may help localize the star formation into a ring. NGC 6782 is a relatively nearby galaxy, residing about 183 million light-years from Earth. The light from galaxies at much larger distances is stretched to longer, redder wavelengths ['redshifted'], due to the expansion of the universe. This means that if astronomers want to compare visible-light images of very distant galaxies with galaxies in our own neighborhood, they should use ultraviolet images of the nearby ones. Astronomers find that the distant galaxies tend to have different structures than nearby ones, even when they

  3. Charged doubly spinning black ring

    SciTech Connect

    Hoskisson, James

    2009-05-15

    This paper devises a procedure for adding fundamental and momentum charges to a neutral 5d solution of Einstein's vacuum equations, when the solution has three Killing vectors. This procedure uses the standard method of boosting and T-dualising a generic metric to give a new two-charge 5d solution to Einstein's vacuum equations. The physical properties of the charged solution are derived and their implications for the solution are then examined, with the two-charge dual spinning black ring being used as an example.

  4. Ring magnet firing angle control

    DOEpatents

    Knott, M.J.; Lewis, L.G.; Rabe, H.H.

    1975-10-21

    A device is provided for controlling the firing angles of thyratrons (rectifiers) in a ring magnet power supply. A phase lock loop develops a smooth ac signal of frequency equal to and in phase with the frequency of the voltage wave developed by the main generator of the power supply. A counter that counts from zero to a particular number each cycle of the main generator voltage wave is synchronized with the smooth AC signal of the phase lock loop. Gates compare the number in the counter with predetermined desired firing angles for each thyratron and with coincidence the proper thyratron is fired at the predetermined firing angle.

  5. Longitudinal dynamics in storage rings

    SciTech Connect

    Colton, E.P.

    1986-01-01

    The single-particle equations of motion are derived for charged particles in a storage ring. Longitudinal space charge is included in the potential assuming an infinitely conducting circular beam pipe with a distributed inductance. The framework uses Hamilton's equations with the canonical variables phi and W. The Twiss parameters for longitudinal motion are also defined for the small amplitude synchrotron oscillations. The space-charge Hamiltonian is calculated for both parabolic bunches and ''matched'' bunches. A brief analysis including second-harmonic rf contributions is also given. The final sections supply calculations of dynamical quantities and particle simulations with the space-charge effects neglected.

  6. Ion trapping in Recycler Ring

    SciTech Connect

    K.Y. Ng

    2004-06-28

    Transverse instabilities have been observed in the antiproton beam stored in the Fermilab Recycler Ring, resulting in a sudden increase in the transverse emittances and a small beam loss. The instabilities appear to occur a few hours after a change in the ramping pattern of the Main Injector which shares the same tunnel. The phenomena have been studied by inducing similar instabilities. However, the mechanism is still unknown. A possible explanation is that the ions trapped in the beam reach such an intensity that collective coupled transverse oscillation occurs. However, there is no direct evidence of the trapped ions at this moment.

  7. Dynamics of dust in Jupiter's gossamer rings

    NASA Astrophysics Data System (ADS)

    Hamilton, D.; Burns, J.; Krueger, H.; Showalter, M.

    2003-04-01

    Over the past several years, the Galileo spacecraft has drastically improved our knowledge of Jupiter's faint rings. We now know the system to be composed of a main ring 7000km wide whose inner edge blossoms into a vertically-extended halo, and a pair of gossamer rings, each one extending inward from a small moon. These moonlets, Thebe and Amalthea, have large orbital tilts and resulting vertical excursions of 1150km and 4300km, respectively. The vertical thicknesses of the two Gossamer rings accurately match these values, providing compelling evidence that the two small satellites act as the dominant sources of ring material. Ring Material is born during high speed impacts onto the moonlet surfaces, after which the material evolves inward under the action of a dissipative force, either Poynting-Robertson Drag or Resonant Charge Variations. The basic framework for the origin and evolution of the Gossamer Rings is well understood, but there are a few loose ends that are not so easily explained: i) an outward extension of the Thebe Ring, ii) the nature of the dissipative force. In this talk I will report my latest dynamical modeling of the Gossamer rings associated with Thebe and Amalthea, and will discuss how in-situ impact data collected by the Galileo dust detector during the first ever ring "fly-through" may help to resolve some of these and other outstanding issues.

  8. Interaction of Vortex Ring with Cutting Plate

    NASA Astrophysics Data System (ADS)

    Musta, Mustafa

    2015-11-01

    The interaction of a vortex ring impinging on a thin cutting plate was made experimentally using Volumetric 3-component Velocitmetry (v3v) technique. The vortex rings were generated with piston-cylinder vortex ring generator using piston stroke-to-diameter ratios and Re at 2-3 and 1500 - 3000, respectively. The cutting of vortex rings below center line leads to the formation of secondary vortices on each side of the plate which is look like two vortex rings, and a third vortex ring propagates further downstream in the direction of the initial vortex ring, which is previously showed by flow visualization study of Weigand (1993) and called ``trifurcation''. Trifurcation is very sensitive to the initial Reynolds number and the position of the plate with respect to the vortex ring generator pipe. The present work seeks more detailed investigation on the trifurcation using V3V technique. Conditions for the formation of trifurcation is analyzed and compared with Weigand (1993). The formed secondary vortex rings and the propagation of initial vortex ring in the downstream of the plate are analyzed by calculating their circulation, energy and trajectories.

  9. Boom and Bust Cycles in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.; Meinke, B. K.; Sremcevic, M.; Albers, N.

    2010-10-01

    7/16/10 12:23 PM UVIS occultation data show clumping in Saturn's F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations perturbed by Mimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by π in the forcing frame. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the aggregate mean size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realistic values of the parameters this creates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag consistent with the UVIS occultation measurements. We conclude that the agitation by the moons at both these locations in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material allows fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would then orbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regions and allow for rare events to aggregate ring particles into solid objects, recycling the ring material and extending the ring lifetime. 7/16/10 12:23 PM 7/16/10 12:23 PM

  10. Boom and Bust Cycles in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Meinke, B. K.; Sremcevic, M.; Albers, N.

    2010-12-01

    Cassini UVIS occultation data show clumping in Saturn’s F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations perturbed by Mimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by roughly π in the forcing frame. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the aggregate mean size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realistic values of the parameters this creates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag roughly consistent with the UVIS occultation measurements. We conclude that the agitation by the moons at both these locations in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material allows fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would then orbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regions and allow for rare events to aggregate ring particles into solid objects, recycling the ring material and extending the ring lifetime.

  11. Saturn's E Ring in Ultraviolet Light

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Visible from Earth only at times of ring plane crossing, Saturn's tenuous E Ring was discovered during the 1966 crossings and imaged again in 1980. From these observations, its color is known to be distinctively blue. The E Ring was captured in ultraviolet light for the first time in this image taken with HST's Wide Field and Planetary Camera on 9 August 1995. Five individual images taken with a broadband 3000 A filter were combined, amounting to a total exposure time of 2200 sec. Shorter exposure images were also obtained with blue, red and infrared filters in order to characterize the ring's color. The peak brightness of the E Ring occurs at 3.9 Saturn radii (235,000 km), coinciding with the orbit of Enceladus. In the HST images it can be traced out to a maximum distance of approximately 8 Rs (480,000 km). The vertical thickness of the ring, on the other hand, is smallest at Enceladus' orbit, with the ring puffing up noticeably at larger distances to 15,000 km or more thick. Also visible in this image, between the E Ring and the overexposed outermost part of the main rings near the lower edge of the frame, is the tenuous, thin, 6000 km-wide G Ring at 2.8 Rs (170,000 km). This is among the first earth-based observations of the G Ring, which was discovered by the Pioneer 11 spacecraft in 1979. Noticeably thinner than the E Ring and more neutral in color, the G Ring is thought to be composed of larger, macroscopic particles, and to pose a significant hazard to spacecraft. The faint diagonal band in the lower right part of the image is due to diffracted light from the heavily-overexposed planet. Credit: Phil Nicholson (Cornell University), Mark Showalter (NASA-Ames/Stanford) and NASA

  12. Perturbations to Saturn's F-ring strands at their closest approach to Prometheus

    USGS Publications Warehouse

    Giuliatti, Winter S.M.; Murray, C.D.; Gordon, M.

    2000-01-01

    The strange morphology of the F ring of Saturn is thought to be caused by the perturbing effects of two close satellites, Prometheus and Pandora. The F ring and the satellites also experience periodic close encounters as a result of differential precession arising from Saturn's oblateness. Using the orbits of the F-ring strands derived by Murray et al. (1997, Icarus 129, 304-316) the behaviour of the ring particles at their closest approach to Prometheus is analysed using numerical simulations. The results show that a gap and a wave are formed in the ring at each encounter with the satellite. However, the gap is expected to have a short lifetime due to keplerian shear. ?? 2000 Elsevier Science Ltd. All rights reserved.

  13. Multi-wavelength studies of Saturn's rings to constrain ring particle properties and ring structure: the VIMS perspective

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Ciarniello, M.; Nicholson, P. D.; Hedmann, M. M.; Clark, R. N.; Cerroni, P.; Spilker, L. J.; Colwell, J.; Bradley, T.

    2012-04-01

    Saturn has the most prominent and complex ring system in our solar system, extending along radial axis from 74658 km (inner C ring edge) to 136780 km (outer A). The physical and dynamical properties of ring particles can be fully understood only using a broad spectral range, which allow us to recognize very different processes. In this context, the scientific goal of our investigation is the study of Saturn's rings particle properties using combined datasets returned from different instruments aboard the Cassini mission. We are merging rings observations and compare results collected by Cassini's UV Imaging Spectrometer (UVIS), Imaging Science Subsystem (ISS), Visual and Infrared Mapping Spectrometer (VIMS) and Composite Infrared Spectrometer (CIRS). Merging multi-wavelength data sets allow us to test different thermal models, combining the effects of particle albedo, regolith composition, grain size and thermal properties with the ring structure. In this work we report about the VIMS contributions to this investigation, coming from the analysis of 0.35-5.1 µm spectra of A, B, C rings and Cassini Division. VIMS, in fact, has the capabilities to determine ring particles composition (water ice vs. chromophores mixed within ice), surface regolith grain size and particle albedo. After having described the dataset considered in this work (several rings radial mosaics taken at 12° ≤ phase ≤ 136° and -21° ≤ opening angle ≤ +5°) and the method to reduce data to spectrograms, we explain how the spectral indicators we have selected (slopes and band parameters) allow us to infer ring particle properties across different regions. Specifically, we report about: 1) the variations induced by illumination phase on visible reddening and water ice bands depth; 2) the average composition and regolith grain size of ring particles in A, B, C rings and CD; 3) an application of Hapke's model to compare VIMS data with synthetic spectra.

  14. Protein Sensors Based on Optical Ring Resonators

    NASA Technical Reports Server (NTRS)

    Lin, Ying; Ksendzov, Alexander

    2006-01-01

    Prototype transducers based on integrated optical ring resonators have been demonstrated to be useful for detecting the protein avidin in extremely dilute solutions. In an experiment, one of the transducers proved to be capable of indicating the presence of avidin at a concentration of as little as 300 pM in a buffer solution a detection sensitivity comparable to that achievable by previously reported protein-detection techniques. These transducers are serving as models for the further development of integrated-optics sensors for detecting small quantities of other proteins and protein-like substances. The basic principle of these transducers was described in Chemical Sensors Based on Optical Ring Resonators (NPO-40601), NASA Tech Briefs, Vol. 29, No. 10 (October 2005), page 32. The differences between the present transducers and the ones described in the cited prior article lie in details of implementation of the basic principle. As before, the resonator in a transducer of the present type is a closed-circuit dielectric optical waveguide. The outermost layer of this waveguide, analogous to the optical cladding layer on an optical fiber, consists of a layer comprising sublayers having indices of refraction lower than that of the waveguide core. The outermost sublayer absorbs the chemical of interest (in this case, avidin). The index of refraction of the outermost sublayer changes with the concentration of absorbed avidin. The resonator is designed to operate with relatively strong evanescent-wave coupling between the outer sublayer and the electromagnetic field propagating along the waveguide core. By virtue of this coupling, the chemically induced change in the index of refraction of the outermost sublayer causes a measurable change in the spectrum of the resonator output.

  15. Flow control of a circular cylinder with O-rings

    NASA Astrophysics Data System (ADS)

    Lim, Hee-Chang; Lee, Sang-Joon

    2004-08-01

    The flow around a circular cylinder is controlled by attaching O-rings to reduce drag force acting on the cylinder. Wind tunnel experiments on the flow around a circular cylinder with and without ring type surface protrusions are carried out to investigate the flow characteristics of the controlled wake. Four experimental models are tested in this study; one smooth cylinder of diameter D (60 mm) and three cylinders fitted with longitudinal O-rings of diameters d=0.0167D, 0.05D and 0.067 D with various pitches. The drag force, mean velocity and turbulence intensity profiles in the near wake behind the cylinders are measured for Reynolds numbers based on the cylinder diameter in the range of ReD=7.8×10 3˜1.2×10 5. Flow field around the cylinders is visualized using a smoke-wire technique to see the flow structure qualitatively. The results are compared with those for a smooth cylinder having the same diameter. At ReD=1.2×10 5, the cylinder fitted with O-rings of d=0.0167 D in a pitch interval of 0.165 D shows the maximum drag reduction of about 9%, compared with the smooth cylinder. The drag reduction effect of O-rings of d=0.067 D is not so high and it has nearly the same value as that of the smooth cylinder. For the O-ring circular, as the Reynolds number increases, the location of peak turbulence intensity shifts downstream and the peak magnitude is decreased. In addition, the vortex shedding frequency has nearly same value as that of the smooth cylinder up to a Reynolds number of 3.2×10 4. Thereafter, the shedding frequency increases and finally disappears as the Reynolds number increases. The visualized flow for the smooth cylinder does not show distinct spanwise variation of flow pattern. However, the size of vortices and vortex formation region formed behind the O-ring cylinder are smaller, compared with the smooth cylinder. In addition, the instantaneous topological flow image shows spanwise variation of V-shaped flow pattern. Consequently, the simple

  16. Ring-type multisoliton dynamics in shallow water.

    PubMed

    Mannan, Abdul; Fedele, Renato; Onorato, Miguel; De Nicola, Sergio; Jovanović, Dušan

    2015-01-01

    The propagation, in a shallow water, of nonlinear ring waves in the form of multisolitons is investigated theoretically. This is done by solving both analytically and numerically the cylindrical (also referred to as concentric) Korteweg-de Vries equation (cKdVE). The latter describes the propagation of weakly nonlinear and weakly dispersive ring waves in an incompressible, inviscid, and irrotational fluid. The spatiotemporal evolution is determined for a cylindrically symmetric response to the free fall of an initially given multisoliton ring. Analytically, localized solutions in the form of tilted solitons are found. They can be thought as single- or multiring solitons formed on a conic-modulated water surface, with an oblique asymptote in arbitrary radial direction (tilted boundary condition). Conversely, the ring solitons obtained from numerical solutions are localized single- or multiring structures (standard solitons), whose wings vanish along all radial directions (standard boundary conditions). It is found that the wave dynamics of these standard ring-type localized structures differs substantially from that of the tilted structures. A detailed analysis is performed to determine the main features of both multiring localized structures, particularly their break-up, multiplet formation, overlapping of pulses, overcoming of one pulse by another, "amplitude-width" complementarity, etc., that are typically ascribed to a solitonlike behavior. For all the localized structures investigated, the solitonlike character of the rings is found to be preserved during (almost) entire temporal evolution. Due to their cylindrical character, each ring belonging to one of these multiring localized structures experiences the physiological decay of the peak and the physiological increase of the width, respectively, while propagating ("amplitude-width" complementarity). As in the planar geometry, i.e., planar Korteweg-de Vries equation (pKdVE), we show that, in the case of the

  17. Construction and testing of the SLD Cerenkov ring imaging detector

    SciTech Connect

    Cavalli-Sforza, M.; Coyle, P.; Coyne, D.; Gagnon, P.; Williams, D.A. . Inst. for Particle Physics); Zucchelli, P. . Ist. di Fisica); Jacques, P.; Piano, R.; Stamer, P. . Serin Physics Lab.); Whitaker, J.S.; Wilson, R.J. . Dept. of Physics); Bean, A.; Caldwell, D.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; HcHugh, S.; Morrison, R.; Witherell, M.; Yellin, S. . Dept. of Physics); Antiligus, P.; Aston, D.; Bienz, T.; Bird, F.; Dosu, S.; Dunwoodie, W.; Hallewell, B.; Kawahara, H.; Kwon, Y.; Leith, D.; Muller, D.; Nagamine, T.; Pavel, T.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Toge, N.; Valvre, J.; Williams, S. ); Abe, K.; Hasegawa, K.; Suekane, F.; Yuta, H. . Dept. of Physics)

    1990-06-01

    The authors report on the construction of the Cherenkov Ring Imaging Detector (CRID) for the SLD experiment at the SLAC Linear Collider and the testing of its components. The authors include results from testing the drift boxes, liquid radiator trays, and mirrors for the barrel CRID. The authors also discuss development of the support systems essential for the operation of the CRID: gas and liquid recirculator systems and monitoring.

  18. Construction and testing of the SLD Cerenkov Ring Imaging Detector

    SciTech Connect

    Cavalli-Sforza, M.; Coyle, P.; Coyne, D.; Gagnon, P.; Williams, D.A.; Zucchelli, P. . Inst. for Particle Physics); Whitaker, J.S.; Wilson, R.J. . Dept. of Physics); Bean, A.; Caldwell, D.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; McHugh, S.; Morrison, R.; Witherell, M.; Yellin, S. . Dept. of Physics); Johns

    1990-01-01

    We report on the construction of the Cerenkov Ring Imaging Detector (CRID) for the SLD experiment at the SLAC Linear Collider and the testing of its components. We include results from testing the drift boxes, liquid radiator trays, and mirrors for the barrel CRID. We also discuss development of the support systems essential for the operation of the CRID: gas and liquid recirculator systems and monitoring. 15 refs., 9 figs.

  19. Reoperation after vascular ring repair.

    PubMed

    Backer, Carl L; Mongé, Michael C; Russell, Hyde M; Popescu, Andrada R; Rastatter, Jeffrey C; Costello, John M

    2014-01-01

    The majority of patients having surgical intervention for a vascular ring have resolution of their symptoms. However, 5% to 10% of these patients develop recurrent symptoms related either to airway or esophageal compression and may require reoperation. In our series of 300 patients with vascular rings, we performed a reoperation on 26 patients, not all of whom were originally operated on at our institution. The four primary indications for reoperation were Kommerell diverticulum (n = 18), circumflex aorta (n = 2), residual scarring (n = 2), and tracheobronchomalacia requiring aortopexy (n = 4). All patients undergoing reoperation have had preoperative evaluation with bronchoscopy and computed tomographic scanning (CT) with 3-dimensional reconstruction. Patients with dysphagia have had a barium esophagram and esophagoscopy. Patients with a Kommerell diverticulum have undergone resection of the diverticulum and transfer of the left subclavian artery to the left carotid artery. The aortic uncrossing procedure has been used in patients with a circumflex aorta. Aortopexy has been used to treat anterior compression of the trachea by the aorta. Results of these reinterventions have been successful in nearly all cases. Lessons learned from these reoperations can be applied to prevent the need for reoperation by properly selecting the correct initial operation. A dedicated team caring for these children consisting of medical imaging, otolaryngology, cardiovascular-thoracic surgery, and critical care is imperative.

  20. Cooling system for three hook ring segment

    SciTech Connect

    Campbell, Christian X.; Eng, Darryl; Lee, Ching-Pang; Patat, Harry

    2014-08-26

    A triple hook ring segment including forward, midsection and aft mounting hooks for engagement with respective hangers formed on a ring segment carrier for supporting a ring segment panel, and defining a forward high pressure chamber and an aft low pressure chamber on opposing sides of the midsection mounting hook. An isolation plate is provided on the aft side of the midsection mounting hook to form an isolation chamber between the aft low pressure chamber and the ring segment panel. High pressure air is supplied to the forward chamber and flows to the isolation chamber through crossover passages in the midsection hook. The isolation chamber provides convection cooling air to an aft portion of the ring segment panel and enables a reduction of air pressure in the aft low pressure chamber to reduce leakage flow of cooling air from the ring segment.

  1. Aqueous Polymer in water alter the Coffee-ring effect

    NASA Astrophysics Data System (ADS)

    Seo, Changdeok; Jang, Daeho; Na, Wonhwi; Park, Sera; Shin, Sehyun

    2015-11-01

    When evaporating in droplet system, small particles move toward an edge by outward capillary flow. This phenomenon is known as coffee-ring effect. In experiments that are required to uniformly accumulate particles, this effect can be fatal. In spite of recent challenges for suppressing the coffee-ring effect, it is still insufficiently controlled in film and droplet with various solutions. For deliberate applications, various materials should be out of influence of coffee-ring effect. In this research, we used a bio-compatible and aqueous polymer, polyethylene glycol (PEG) for altering the coffee-ring effect. The influence of PEG on the evaporation of drying colloidal droplets is examined in a wide range of initial concentrations. Adding PEG to water causes a strong vortex flow near the edge of droplet and subsequently leads to significantly uniform patterns of colloidal particle deposition after evaporation. We found the vortex phenomenon by combination of radially outward capillary flow and radially inward Marangoni flows are induced by the radial variation of polymer concentration along the air?water interface. Furthermore, increasing polymer concentration significantly alters the characteristic of ``Marangoni Vortex'' and leads to reproducible patterning of conical structures.

  2. Ring-Constraint High-Pressure Torsion Process

    NASA Astrophysics Data System (ADS)

    Joo, Soo-Hyun; Kim, Hyoung Seop

    2016-07-01

    In this study, a constraint ring around a workpiece was employed in order to develop back pressure in addition to a compressive die pressure in high-pressure torsion (HPT) process. The influence of the constraint ring during the HPT process was analyzed using the finite element method and experimental analyses. Greater back pressure was developed when a ring of a stronger material enveloped the workpiece. In the experiments, fracture of a brittle material [ e.g., La-based bulk metallic glass (BMG)], was limited even at large shear strain (~315) during the ring-constraint HPT (RC-HPT) process due to reduced tensile stress at the edge of the deforming BMG workpiece. Furthermore, the RC-HPT process had beneficial effects on powder consolidation and bonding. The RC-HPT process exhibited smaller loss of material than did the conventional semi-constrained HPT process. The Cu disk produced by the powder RC-HPT had smaller grain sizes because back pressure generated more dislocations and finer grain size in the Cu workpiece.

  3. A Model For the Limiting Time in Vortex Ring Formation

    NASA Technical Reports Server (NTRS)

    Shariff, Karim; Gharib, Morteza; Rambod, Edmond; Merriam, Marshal (Technical Monitor)

    1997-01-01

    In another presentation, Gharib et at provide experimental results to show that when a vortex ring is created from a pipe by a piston, there is a limiting time or piston stroke length beyond which multiple rings appear. This time appeared to be insensitive to piston velocity history and Reynolds number. Nature might exploit such a. limit in different contexts to coherently deliver mass or momentum flux with the least number of strokes. Here, a simple hypothesis is considered: the limiting time occurs when the apparatus is no longer able to deliver energy at a rate compatible with the requirement, due to Kelvin, that a steady vortex ring have maximum energy given circulation and impulse. More specifically, the limit is expected to occur when the quantity alpha = E/square root of Gamma(sup 3)I delivered by the piston drops below the value, alpha(sub lim) for a limiting steady vortex ring solution. The resulting predictions agree very well with the experiments (after using alpha(sub lim) measured using the experimental flow fields). The insensitivity to piston history also emerges from the model. Finally, piston histories are designed that may extend the limiting time somewhat.

  4. Saturn Ring Data Analysis and Thermal Modeling

    NASA Technical Reports Server (NTRS)

    Dobson, Coleman

    2011-01-01

    CIRS, VIMS, UVIS, and ISS (Cassini's Composite Infrared Specrtometer, Visual and Infrared Mapping Spectrometer, Ultra Violet Imaging Spectrometer and Imaging Science Subsystem, respectively), have each operated in a multidimensional observation space and have acquired scans of the lit and unlit rings at multiple phase angles. To better understand physical and dynamical ring particle parametric dependence, we co-registered profiles from these three instruments, taken at a wide range of wavelengths, from ultraviolet through the thermal infrared, to associate changes in ring particle temperature with changes in observed brightness, specifically with albedos inferred by ISS, UVIS and VIMS. We work in a parameter space where the solar elevation range is constrained to 12 deg - 14 deg and the chosen radial region is the B3 region of the B ring; this region is the most optically thick region in Saturn's rings. From this compilation of multiple wavelength data, we construct and fit phase curves and color ratios using independent dynamical thermal models for ring structure and overplot Saturn, Saturn ring, and Solar spectra. Analysis of phase curve construction and color ratios reveals thermal emission to fall within the extrema of the ISS bandwidth and a geometrical dependence of reddening on phase angle, respectively. Analysis of spectra reveals Cassini CIRS Saturn spectra dominate Cassini CIRS B3 Ring Spectra from 19 to 1000 microns, while Earth-based B Ring Spectrum dominates Earth-based Saturn Spectrum from 0.4 to 4 microns. From our fits we test out dynamical thermal models; from the phase curves we derive ring albedos and non-lambertian properties of the ring particle surfaces; and from the color ratios we examine multiple scattering within the regolith of ring particles.

  5. Interferometric ring lasers and optical devices

    DOEpatents

    Hohimer, J.P.; Craft, D.C.

    1995-03-14

    Two ring diode lasers are optically coupled together to produce tunable, stable output through a Y-junction output coupler which may also be a laser diode or can be an active waveguide. These devices demonstrate a sharp peak in light output with an excellent side-mode-rejection ratio. The rings can also be made of passive or active waveguide material. With additional rings the device is a tunable optical multiplexer/demultiplexer. 11 figs.

  6. Boundary value problem for black rings

    SciTech Connect

    Morisawa, Yoshiyuki; Tomizawa, Shinya; Yasui, Yukinori

    2008-03-15

    We study the boundary value problem for asymptotically flat stationary black ring solutions to the five-dimensional vacuum Einstein equations. Assuming the existence of two additional commuting axial Killing vector fields and the horizon topology of S{sup 1}xS{sup 2}, we show that the only asymptotically flat black ring solution with a regular horizon is the Pomeransky-Sen'kov black ring solution.

  7. Interferometric ring lasers and optical devices

    DOEpatents

    Hohimer, John P.; Craft, David C.

    1995-01-01

    Two ring diode lasers are optically coupled together to produce tunable, stable output through a Y-junction output coupler which may also be a laser diode or can be an active waveguide. These devices demonstrate a sharp peak in light output with an excellent side-mode-rejection ratio. The rings can also be made of passive or active waveguide material. With additional rings the device is a tunable optical multiplexer/demultiplexer.

  8. Keck infrared observations of Saturn's main rings bracketing Earth's August 1995 ring plane crossing

    NASA Astrophysics Data System (ADS)

    Verbanac, Giuli; de Pater, Imke; Showalter, Mark R.; Lissauer, Jack J.

    2005-03-01

    We present results of near-infrared (2.26 μm) observations of Saturn's main rings taken with the W.M. Keck telescope during August 8-11, 1995, surrounding the time that Earth crossed Saturn's ring plane. These observations provide a unique opportunity to study the evolution of the ring brightness in detail, and by combining our data with Hubble Space Telescope (HST) results (Nicholson et al., 1996, Science 272, 453-616), we extend the 12-hour HST time span to several days around the time of ring plane crossing (RPX). In this paper, we focus on the temporal evolution of the brightness in Saturn's main rings. We examine both edge-on ring profiles and radial profiles obtained by "onion-peeling" the edge-on data. Before RPX, when the dark (unlit) face of the rings was observed, the inner C ring (including the Colombo gap), the Maxwell gap, Cassini Division and F ring region were very bright in transmitted light. After RPX, the main rings brighten rapidly, as expected. The profiles show east-west asymmetries both before and after RPX. Prior to RPX, the evolution in ring brightness of the Keck and HST data match one another quite well. The west side of the rings showed a nonlinear variation in brightness during the last hours before ring plane crossing, suggestive of clumping and longitudinal asymmetries in the F ring. Immediately after RPX, the east side of the rings brightened more rapidly than the west. A quantitative comparison of the Keck and HST data reveals that the rings were redder before RPX than after; we ascribe this difference to the enhanced multiple scattering of photons passing through to the unlit side of the rings.

  9. Celebrating Soft Matter's 10th Anniversary: Topology matters: structure and dynamics of ring polymers.

    PubMed

    Richter, D; Goossen, S; Wischnewski, A

    2015-11-28

    Considering topology among all polymer architectures polymer rings are unique, as they are the simplest closed structures without ends. In this review we present recent experimental advances addressing the structure and dynamics of rings. We focus mainly on neutron scattering results that reveal experimental insight on a molecular scale. We first briefly reflect on the progress in ring chemistry that made the experimental access possible. Structural investigations characterizing rings as compact objects in the melts are put into theoretical context. In contrast to the plateau regime common for all other high molecular weight polymer systems, the dynamic modulus of pure ring systems is characterized by a power law decay, while the viscosity displays a much weaker molecular weight dependence as a corresponding linear melt. The dynamics of ring melts is uniquely addressed by neutron spin-echo spectroscopy. The sub-diffusive center of mass motion at short times agrees well with simulation as well as theoretical concepts. In the internal dynamics the basic length scale of the ring molecule, the loop size, manifests itself clearly. The experiments reveal strong evidence for loop motions and call for further theoretical work describing them. Finally, small fractions of ring molecules in linear melts turn out to be very sensitive probes in order to scrutinize the dynamics of the host with the potential to reveal fundamental aspects of the dynamics of branched polymer systems. PMID:26406787

  10. Celebrating Soft Matter's 10th Anniversary: Topology matters: structure and dynamics of ring polymers.

    PubMed

    Richter, D; Goossen, S; Wischnewski, A

    2015-11-28

    Considering topology among all polymer architectures polymer rings are unique, as they are the simplest closed structures without ends. In this review we present recent experimental advances addressing the structure and dynamics of rings. We focus mainly on neutron scattering results that reveal experimental insight on a molecular scale. We first briefly reflect on the progress in ring chemistry that made the experimental access possible. Structural investigations characterizing rings as compact objects in the melts are put into theoretical context. In contrast to the plateau regime common for all other high molecular weight polymer systems, the dynamic modulus of pure ring systems is characterized by a power law decay, while the viscosity displays a much weaker molecular weight dependence as a corresponding linear melt. The dynamics of ring melts is uniquely addressed by neutron spin-echo spectroscopy. The sub-diffusive center of mass motion at short times agrees well with simulation as well as theoretical concepts. In the internal dynamics the basic length scale of the ring molecule, the loop size, manifests itself clearly. The experiments reveal strong evidence for loop motions and call for further theoretical work describing them. Finally, small fractions of ring molecules in linear melts turn out to be very sensitive probes in order to scrutinize the dynamics of the host with the potential to reveal fundamental aspects of the dynamics of branched polymer systems.

  11. Passive Vibration Control of Airborne Equipment using a Circular Steel Ring

    NASA Technical Reports Server (NTRS)

    Ellison, Joseph; Ahmadi, Goodarz; Kehoe, Mike

    1997-01-01

    Vibration isolation is needed to protect avionics equipment from adverse aircraft vibration environments. Passive isolation is the simplest means to achieve this goal. The system used here consists of a circular steel ring with a lump mass on top and exposed to base excitation. Sinusoidal and filtered zero-mean Gaussian white noise are used to excite the structure and the acceleration response spectra at the top of the ring are computed. An experiment is performed to identify the natural frequencies and modal damping of the circular ring. Comparison is made between the analytical and experimental results and good agreement is observed. The ring response is also evaluated with a concentrated mass attached to the top of the ring. The effectiveness of the ring in isolating the equipment from base excitation is studied. The acceleration response spectra of a single degree of freedom system attached to the top of the ring are evaluated and the results are compared with those exposed directly to the base excitation. It is shown that a properly designed ring could effectively protect the avionics from possible damaging excitation levels.

  12. Report of the eRHIC Ring-Ring Working Group

    SciTech Connect

    Aschenauer, E. C.; Berg, S.; Blaskiewicz, M.; Brennan, M.; Fedotov, A.; Fischer, W.; Litvinenko, V.; Montag, C.; Palmer, R.; Parker, B.; Peggs, S.; Ptitsyn, V.; Ranjbar, V.; Tepikian, S.; Trbojevic, D.; Willeke, F.

    2015-10-13

    This report evaluates the ring-ring option for eRHIC as a lower risk alternative to the linac-ring option. The reduced risk goes along with a reduced initial luminosity performance. However, a luminosity upgrade path is kept open. This upgrade path consists of two branches, with the ultimate upgrade being either a ring-ring or a linac-ring scheme. The linac-ring upgrade could be almost identical to the proposed linac-ring scheme, which is based on an ERL in the RHIC tunnel. This linac-ring version has been studied in great detail over the past ten years, and its significant risks are known. On the other hand, no detailed work on an ultimate performance ring-ring scenario has been performed yet, other than the development of a consistent parameter set. Pursuing the ring-ring upgrade path introduces high risks and requires significant design work that is beyond the scope of this report.

  13. Cassini Radio Occultation Results for Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Marouf, E.; French, R.; Rappaport, N.; McGhee, C.; Wong, K.; Thomson, F.

    2005-12-01

    The Cassini spacecraft completed a set of eight radio occultation observations of Saturn's rings during the period May 2 to September 5, 2005. The observation geometry was optimized to provide multiple ring longitude measurements at three radio wavelengths (0.94, 3.6, 13 cm; Ka-, X-, and S-band, respectively). A normal optical depth profile, a phase shift profile, as well as spectrogram of the near-forward scattered signal are constructed at each observation longitude and wavelength. High spatial resolution X-band optical depth profiles (up to 400 m so far) reveal for the first time detailed structure of Ring B, Saturn's most massive ring feature, as well as structure of many dynamical ring features including density and bending waves driven by exterior satellites, wakes due to embedded satellites, ring gaps, narrow eccentric gap-embedded ringlets, sharp ring edges, among others. Remarkable variability of ring structure with longitude is observed, including prominent asymmetry in Ring A. The Ka/X/S optical depth observations are used to characterize variability in the abundance of particle sizes that populate observed structure over the millimeters to centimeters radius range. Combined, the Ka/X/S optical depth and spectrograms of the near-forward scattered signal provide complementary information about the abundance of the meters size particles and their spatial distribution, including potential crowding, clustering, and preferred orientations.

  14. Apse-Alignment of the Uranian Rings

    NASA Technical Reports Server (NTRS)

    Mosqueira, I.; Estrada, P. R.

    2000-01-01

    An explanation of the dynamical mechanism for apse-alignment of the eccentric Uranian rings is necessary before observations can be used to determine properties such as ring masses, particle sizes, and elasticities. The leading model relies on the ring self-gravity to accomplish this task, yet it yields equilibrium masses which are not in accord with Voyager radio measurements. We explore possible solutions such that the self-gravity and the collisional terms are both involved in the process of apse-alignment. We consider limits that correspond to a hot and a cold ring, and show that pressure terms may play a significant role in the equilibrium conditions for the narrow Uranian rings. In the cold ring case, where the scale height of the ring near periapse is comparable to the ring particle size, we introduce a new pressure correction pertaining to a region of the ring where the particles are locked in their relative positions and jammed against their neighbors, and the velocity dispersion is so low that the collisions are nearly elastic. In this case, we find a solution such that the ring self-gravity maintains apse-alignment against both differential precession (m = 1 mode) and the fluid pressure. We apply this model to the Uranian alpha ring, and show that, compared to the previous self-gravity model, the mass estimate for this ring increases by an order of magnitude. In the case of a hot ring, where the scale height can reach a value as much as fifty times larger than a particle size, we find velocity dispersion profiles that result in pressure forces which act in such a way as to alter the ring equilibrium conditions, again leading to a ring mass increase of an order of magnitude; however, such a velocity dispersion profile would require a different mechanism than is currently envisioned for establishing heating/cooling balance in a finite-sized, inelastic particle ring. Finally, we introduce an important correction to the model of Chiang and Goldreich.

  15. Condenser for illuminating a ring field

    DOEpatents

    Sweatt, W.C.

    1994-11-01

    A series of segments of a parent aspheric mirror having one foci at a point source of radiation and the other foci at the radius of a ring field have all but one or all of their beams translated and rotated by sets of mirrors such that all of the beams pass through the real entrance pupil of a ring field camera about one of the beams and fall onto the ring field radius as a coincident image as an arc of the ring field. 5 figs.

  16. Condenser for illuminating a ring field

    DOEpatents

    Sweatt, William C.

    1994-01-01

    A series of segments of a parent aspheric mirror having one foci at at a si-point source of radiation and the other foci at the radius of a ring field have all but one or all of their beams translated and rotated by sets of mirrors such that all of the beams pass through the real entrance pupil of a ring field camera about one of the beams and fall onto the ring field radius as a coincident image as an arc of the ring field.

  17. Simulation of Rings about Ellipsoidal Bodies

    NASA Astrophysics Data System (ADS)

    Gupta, Akash; Nadkarni-Ghosh, Sharvari; Sharma, Ishan

    2016-10-01

    Recent discovery of rings around Chariklo, a centaur orbiting the Sun (F. Braga-Ribas et al., 2014) and speculations of rings around minor planet, Chiron (Ortiz et al., 2015), Saturn's satellites, Rhea (Jones et al., 2008; Schenk et al., 2011), Iapetus (Ip, 2006) or exoplanets, suggest that rings about non-spherical bodies is perhaps a more general phenomenon than anticipated. As a first step towards understanding such systems, we examine the dynamical behavior of rings around similar bodies using N-body simulations. Our code employs the `local simulation method' (Wisdom & Tremaine, 1988; Salo, 1995) and accounts for particle interactions via collisions using Discrete Element Method (Cundall & Strack, 1978; Bhateja et al., 2016) and mutual gravitation. The central body has been modeled as an axisymmetric ellipsoid characterized by its axis ratio, or defined via characteristic frequencies (circular, vertical and epicyclic frequency) representing the gravitational field of an axisymmetric body. We vary the central body's characterizing parameter and observe the change in various ring properties like the granular temperature, impact frequency, radial width and vertical thickness. We also look into the effect on ring properties upon variation in the size of the central body-ring system. Further, we investigate the role of characteristic frequencies in dictating the ring dynamics, and how this could help in qualitatively estimating the ring dynamics about any arbitrary central body with symmetry about the equatorial plane and the axis normal to it.

  18. Dynamical and photometric studies of Saturn's rings

    SciTech Connect

    Dones, H.C. Jr.

    1987-01-01

    Imaging and occultation data returned by the two Voyager spacecraft have deepened understanding of dynamical processes operating in Saturn's rings. Saturn's outermost, or A, ring was investigated here in light of this data. Most structure seen in the A ring is caused by spiral density waves, which are regular oscillations in the optical depth of the rings. Density waves are excited at horizontal resonances with the inner satellites of Saturn. Most waves are weakly nonlinear and propagate for only a few wavelengths before they damp. The damping length is somewhat longer in regions of high optical depth. A theory of the viscous damping of nonlinear density waves in the rings is formulated. The energy input by the wave must be offset, in a steady state, by dissipation through inelastic collisions between ring particles. Voyage images of the A ring are analyzed to determine how the brightness of different regions varies with illumination and viewing geometry. The data are modeled with a radiative-transfer code that includes the illumination of the rings by the Sun and Saturn. Finally, the azimuthally asymmetric reflectivity of the A ring seen in Voyager images taken in backscatter is characterized.

  19. What Perturbs the ggrdgr Rings of Uranus?

    PubMed

    French, R G; Kangas, J A; Elliot, J L

    1986-01-31

    The gamma and delta rings have by far the largest radial perturbations of any of the nine known Uranian rings. These two rings deviate from Keplerian orbits, having typical root-mean-square residuals of about 3 kilometers (compared to a few hundred meters for the other seven known rings). Possible causes for the perturbations include nearby shepherd satellites and Lindblad resonances. If shepherd satellites are responsible, they could be as large as several tens of kilometers in diameter. The perturbation patterns of the gamma and delta rings have been examined for evidence of Lindblad resonances of azimuthal wave number m = 0, 1, 2, 3, and 4. The beta ring radial residuals are well matched by a 2:1 Lindblad resonance. If this represents a real physical phenomenon and is not an artifact of undersampling, then the most plausible interpretation is that there is an undiscovered satellite orbiting 76,522 +/- 8 kilometers from Uranus, with an orbital period of 15.3595 +/- 0.0001 hours and a radius of 75 to 100 kilometers. Such a satellite would be easily detected by the Voyager spacecraft when it encounters Uranus. The 2:1 resonance location is 41 +/- 9 kilometers inside the delta ring, which makes it unlikely that the resonance is due to a viscous instability within the ring. In contrast, no low-order Lindblad resonance matches the gamma ring perturbations, which are probably caused by one or more shepherd satellites large enough to be clearly visible in Voyager images. PMID:17776019

  20. What Perturbs the ggrdgr Rings of Uranus?

    PubMed

    French, R G; Kangas, J A; Elliot, J L

    1986-01-31

    The gamma and delta rings have by far the largest radial perturbations of any of the nine known Uranian rings. These two rings deviate from Keplerian orbits, having typical root-mean-square residuals of about 3 kilometers (compared to a few hundred meters for the other seven known rings). Possible causes for the perturbations include nearby shepherd satellites and Lindblad resonances. If shepherd satellites are responsible, they could be as large as several tens of kilometers in diameter. The perturbation patterns of the gamma and delta rings have been examined for evidence of Lindblad resonances of azimuthal wave number m = 0, 1, 2, 3, and 4. The beta ring radial residuals are well matched by a 2:1 Lindblad resonance. If this represents a real physical phenomenon and is not an artifact of undersampling, then the most plausible interpretation is that there is an undiscovered satellite orbiting 76,522 +/- 8 kilometers from Uranus, with an orbital period of 15.3595 +/- 0.0001 hours and a radius of 75 to 100 kilometers. Such a satellite would be easily detected by the Voyager spacecraft when it encounters Uranus. The 2:1 resonance location is 41 +/- 9 kilometers inside the delta ring, which makes it unlikely that the resonance is due to a viscous instability within the ring. In contrast, no low-order Lindblad resonance matches the gamma ring perturbations, which are probably caused by one or more shepherd satellites large enough to be clearly visible in Voyager images.

  1. Development of a liquid metal slip ring

    NASA Technical Reports Server (NTRS)

    Weinberger, S. M.

    1972-01-01

    A liquid metal slip ring/solar orientation mechanism was designed and a model tested. This was a follow-up of previous efforts for the development of a gallium liquid metal slip ring in which the major problem was the formation and ejection of debris. A number of slip ring design approaches were studied. The probe design concept was fully implemented with detail drawings and a model was successfully tested for dielectric strength, shock vibration, acceleration and operation. The conclusions are that a gallium liquid metal slip ring/solar orientation mechanism is feasible and that the problem of debris formation and ejection has been successfully solved.

  2. FIFTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

    SciTech Connect

    Daugherty, W.; Hoffman, E.

    2010-11-01

    A series of experiments to monitor the aging performance of Viton{sup reg.} GLT O-rings used in the Model 9975 package has been ongoing for six years at the Savannah River National Laboratory. Sixty-seven 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 at nominal six month intervals to determine if they meet the criterion of leaktightness 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 for 36 GLT O-ring fixtures at 200--350 F. Room temperature leak test failures have been experienced in 5 of the GLT O-ring fixtures aging at 300 and 350 F, and in all 3 of the GLT O-ring fixtures aging at higher temperatures. No failures have yet been observed in GLT O-ring fixtures aging at 200 F for 30--48 months, which is still bounding to O-ring temperatures during storage in KAMS. 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 or 300 F for 19 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--95%. This is significantly greater than seen to date for packages inspected during KAMS field surveillance (23% average). For GLT O-rings, service life based on the room temperature leak rate criterion is comparable to that predicted by compression stress relaxation (CSR) data at higher temperatures (350--400 F). While there are no comparable failure data yet at aging temperatures below 300 F, extrapolations of the data for GLT O-rings suggests that CSR model predictions provide a conservative prediction of

  3. The Conversion and operation of the Cornell electron storage ring as a test accelerator (cesrta) for damping rings research and development

    SciTech Connect

    Palmer, M.A.; Alexander, J.; Byrd, J.; Celata, C.M.; Corlett, J.; De Santis, S.; Furman, M.; Jackson, A.; Kraft, R.; Munson, D.; Penn, G.; Plate, D.; Rawlins, A.; Venturini, M.; Zisman, M.; Billing, M.; Calvey, J.; Chapman, S.; Codner, G.; Conolly, C.; Crittenden, J.; Dobbins, J.; Dugan, G.; Fontes, E.; Forster, M.; Gallagher, R.; Gray, S.; Greenwald, S.; Hartill, D.; Hopkins, W.; Kandaswamy, J.; Kreinick, D.; Li, Y.; Liu, X.; Livezey, J.; Lyndaker, A.; Medjidzade, V.; Meller, R.; Peck, S.; Peterson, D.; Rendina, M.; Revesz, P.; Rice, D.; Rider, N.; Rubin, D.; Sagan, D.; Savino, J.; Seeley, R.; Sexton, J.; Shanks, J.; Sikora, J.; Smolenski, K.; Strohman, C.; Temnykh, A.; tigner, M.; Whitney, W.; Williams, H.; Vishniakou, S.; Wilkens, T.; Harkay, K.; Holtzapple, R.; Smith, E.; Jones, J.; Wolski, A.; He, Y.; Ross, M.; Tan, C.Y.; Zwaska, R.; Flanagan, J.; Jain, P.; Kanazawa, K.; Ohmi, K.; Sakai, H.; Shibata, K.; Suetsugu, Y.; Kharakh, D.; Pivi, M.; Wang, L.

    2009-05-01

    In March of 2008, the Cornell Electron Storage Ring (CESR) concluded twenty eight years of colliding beam operations for the CLEO high energy physics experiment. We have reconfigured CESR as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. The primary goals of the CesrTA program are to achieve a beam emittance approaching that of the ILC Damping Rings with a positron beam, to investigate the interaction of the electron cloud with both low emittance positron and electron beams, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies (in particular a fast x-ray beam size monitor capable of single pass measurements of individual bunches). We report on progress with the CESR conversion activities, the status and schedule for the experimental program, and the first experimental results that have been obtained.

  4. Concentric ring flywheel with hooked ring carbon fiber separator/torque coupler

    DOEpatents

    Kuklo, Thomas C.

    1999-01-01

    A concentric ring flywheel with expandable separators, which function as torque couplers, between the rings to take up the gap formed between adjacent rings due to differential expansion between different radius rings during rotation of the flywheel. The expandable separators or torque couplers include a hook-like section at an upper end which is positioned over an inner ring and a shelf-like or flange section at a lower end onto which the next adjacent outer ring is positioned. As the concentric rings are rotated the gap formed by the differential expansion there between is partially taken up by the expandable separators or torque couplers to maintain torque and centering attachment of the concentric rings.

  5. Concentric ring flywheel with hooked ring carbon fiber separator/torque coupler

    DOEpatents

    Kuklo, T.C.

    1999-07-20

    A concentric ring flywheel with expandable separators, which function as torque couplers, between the rings to take up the gap formed between adjacent rings due to differential expansion between different radius rings during rotation of the flywheel. The expandable separators or torque couplers include a hook-like section at an upper end which is positioned over an inner ring and a shelf-like or flange section at a lower end onto which the next adjacent outer ring is positioned. As the concentric rings are rotated the gap formed by the differential expansion there between is partially taken up by the expandable separators or torque couplers to maintain torque and centering attachment of the concentric rings. 2 figs.

  6. Mechanical support of a ceramic gas turbine vane ring

    DOEpatents

    Shi, Jun; Green, Kevin E.; Mosher, Daniel A.; Holowczak, John E.; Reinhardt, Gregory E.

    2010-07-27

    An assembly for mounting a ceramic turbine vane ring onto a turbine support casing comprises a first metal clamping ring and a second metal clamping ring. The first metal clamping ring is configured to engage with a first side of a tab member of the ceramic turbine vane ring. The second metal clamping ring is configured to engage with a second side of the tab member such that the tab member is disposed between the first and second metal clamping rings.

  7. The eddy-current technique for nondestructive evaluation of generator retaining rings: Feasibility study: Interim report

    SciTech Connect

    Elmo, P.M.; Nottingham, L.D.

    1988-05-01

    An evaluation of the feasibility of using eddy current nondestructive inspection techniques to detect intergranular stress corrosion in generator rotor retaining rings was conducted by the EPRI NDE Center. Experiments were conducted using a bend-bar containing representative stress corrosion damage, a calibration block containing electrical discharge machined (EDM) notches, and four retired retaining rings containing EDM notches and stress corrosion damage. An eddy current transducer transport was designed and fabricated to interface with an existing computer-controlled, two-axis positioner and digital eddy current data acquisition system. Test results of experiments performed with this equipment on the retaining ring test-bed provided experimental validation of the eddy current method's feasibility as a retaining ring inspection method. Details are given of the system and its performance under laboratory and simulated service-inspection conditions. 9 refs., 47 figs.

  8. DEVELOPMENT OF A HYDROGEN AND DEUTERIUM POLARIZED GAS TARGET FOR APPLICATION IN STORAGE RINGS

    SciTech Connect

    Willy Haeberli

    2009-06-18

    The exploration of spin degrees of freedom in nuclear and high-energy interactions requires the use of spin-polarized projectiles and/or spin-polarized targets. During the last two decades, the use of external beams from cyclotrons has to a large extent been supplanted by use of circulating beams stored in storage rings. In these experiments, the circulating particles pass millions of times through targets internal to the ring. Thus the targets need to be very thin to avoid beam loss by scattering out of the acceptance aperture of the ring.

  9. The heavy ion cooler-storage-ring project (HIRFL-CSR) at Lanzhou

    NASA Astrophysics Data System (ADS)

    Xia, J. W.; Zhan, W. L.; Wei, B. W.; Yuan, Y. J.; Song, M. T.; Zhang, W. Z.; Yang, X. D.; Yuan, P.; Gao, D. Q.; Zhao, H. W.; Yang, X. T.; Xiao, G. Q.; Man, K. T.; Dang, J. R.; Cai, X. H.; Wang, Y. F.; Tang, J. Y.; Qiao, W. M.; Rao, Y. N.; He, Y.; Mao, L. Z.; Zhou, Z. Z.

    2002-08-01

    HIRFL-CSR, a new ion Cooler-Storage-Ring (CSR) project, is the post-acceleration system of the Heavy Ion Research Facility in Lanzhou (HIRFL). It consists of a main ring (CSRm) and an experimental ring (CSRe). From the HIRFL cyclotron system the heavy ions will be accumulated, cooled and accelerated in the CSRm, then extracted fast to produce radioactive ion beams (RIB) or highly charged heavy ions. Those secondary beams will be accepted and stored by the CSRe for many internal-target experiments with electron cooling.

  10. Experimental determination of gravitomagnetic effects by means of ring lasers

    NASA Astrophysics Data System (ADS)

    Tartaglia, Angelo

    2013-08-01

    A new experiment aimed to the detection of the gravito-magnetic Lense-Thirring effect at the surface of the Earth will be presented; the name of the experiment is GINGER. The proposed technique is based on the behavior of light beams in ring-lasers, also known as gyrolasers. A three-dimensional array of ringlasers will be attached to a rigid "monument"; each ring will have a different orientation in space. Within the space-time of a rotating mass the propagation of light is indeed anisotropic; part of the anisotropy is purely kinematical (Sagnac effect), part is due to the interaction between the gravito-electric field of the source and the kinematical motion of the observer (de Sitter effect), finally there is a contribution from the gravito-magnetic component of the Earth (gravito-magnetic frame dragging or Lense-Thirring effect). In a ring-laser a light beam traveling counterclockwise is superposed to another beam traveling in the opposite sense. The anisotropy in the propagation leads to standing waves with slightly different frequencies in the two directions; the final effect is a beat frequency proportional to the size of the instrument and its effective rotation rate in space, including the gravito-magnetic drag. Current laser techniques and the performances of the best existing ring-lasers allow at the moment a sensitivity within one order of magnitude of the required accuracy for the detection of gravito-magnetic effects, so that the objective of GINGER is in the range of feasibility and aims to improve the sensitivity of a couple of orders of magnitude with respect to present. The experiment will be underground, probably in the Gran Sasso National Laboratories in Italy, and is based on an international collaboration among four Italian groups, the Technische Universität München and the University of Canterbury in Christchurch (NZ).

  11. Microfabricated optofluidic ring resonator structures

    PubMed Central

    Scholten, Kee; Fan, Xudong; Zellers, Edward. T.

    2011-01-01

    We describe the fabrication and preliminary optical characterization of rugged, Si-micromachined optofluidic ring resonator (μOFRR) structures consisting of thin-walled SiOx cylinders with expanded midsections designed to enhance the three-dimensional confinement of whispering gallery modes (WGMs). These μOFRR structures were grown thermally at wafer scale on the interior of Si molds defined by deep-reactive-ion etching and pre-treated to reduce surface roughness. Devices 85-μm tall with 2-μm thick walls and inner diameters ranging from 50 to 200 μm supported pure-mode WGMs with Q-factors >104 near 985 nm. Advantages for eventual vapor detection in gas chromatographic microsystems are highlighted. PMID:22053110

  12. Formation dynamics in geostationary ring

    NASA Astrophysics Data System (ADS)

    Spiridonova, Sofya

    2016-08-01

    A relative motion model for a satellite formation composed of two Earth-orbiting spacecraft located in the geostationary ring is developed taking into account major gravitational and non-gravitational forces. A previously existing model featuring perturbation due to J_2 is enhanced by the perturbations due to solar radiation pressure arising from unequal area-to-mass ratios, as well as the secular and long-periodic gravitational perturbations due to the Sun and the Moon. The extended relative motion model is validated using several typical formation geometries against a reference generated by numerical integration of the absolute orbits of the two spacecraft. The results of this work can find application in future on-orbit servicing and formation flying missions in near-geostationary orbit.

  13. Human Arterial Ring Angiogenesis Assay.

    PubMed

    Seano, Giorgio; Primo, Luca

    2016-01-01

    In this chapter we describe a model of human angiogenesis where artery explants from umbilical cords are embedded in gel matrices and subsequently produce capillary-like structures. The human arterial ring (hAR) assay is an innovative system that enables three-dimensional (3D) and live studies of human angiogenesis. This ex vivo model has the advantage of recapitulating several steps of angiogenesis, including endothelial sprouting, migration, and differentiation into capillaries. Furthermore, it can be exploited for (1) identification of new genes regulating sprouting angiogenesis, (2) screening for pro- or anti-angiogenic drugs, (3) identification of biomarkers to monitor the efficacy of anti-angiogenic regimens, and (4) dynamic analysis of tumor microenvironmental effects on vessel formation. PMID:27172955

  14. Size distribution of ring polymers

    NASA Astrophysics Data System (ADS)

    Medalion, Shlomi; Aghion, Erez; Meirovitch, Hagai; Barkai, Eli; Kessler, David A.

    2016-06-01

    We present an exact solution for the distribution of sample averaged monomer to monomer distance of ring polymers. For non-interacting and local-interaction models these distributions correspond to the distribution of the area under the reflected Bessel bridge and the Bessel excursion respectively, and are shown to be identical in dimension d ≥ 2, albeit with pronounced finite size effects at the critical dimension, d = 2. A symmetry of the problem reveals that dimension d and 4 - d are equivalent, thus the celebrated Airy distribution describing the areal distribution of the d = 1 Brownian excursion describes also a polymer in three dimensions. For a self-avoiding polymer in dimension d we find numerically that the fluctuations of the scaled averaged distance are nearly identical in dimension d = 2, 3 and are well described to a first approximation by the non-interacting excursion model in dimension 5.

  15. VUV optical ring resonator for Duke storage ring free electron laser

    SciTech Connect

    Park, S.H.; Litvinenko, V.N.; Madey, J.M.J.

    1995-12-31

    The conceptual design of the multifaceted-mirror ring resonator for Duke storage ring VUV FEL is presented. The expected performance of the OK-4 FEL with ring resonator is described. We discuss in this paper our plans to study reflectivity of VUV mirrors and their resistivity to soft X-ray spontaneous radiation from OK-4 undulator.

  16. Signals from Microwave Unstable Beams in the SLC Damping Rings

    SciTech Connect

    Podobedev, Boris

    1999-04-05

    The longitudinal microwave instability is present in the SLC damping rings during routine operations. Experimental studies of the instability at nominal conditions have been reported previously. To complement those studies and better understand the properties of the instability a series of dedicated experiments were performed under a broad range of operating parameters. These experiments included spectral measurements of BPM signals as well as time domain diagnostics using a custom detecting circuit. This paper describes the techniques, the results and discusses possible interpretations of these measurements.

  17. MeV proton flux predictions near Saturn's D ring

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Roussos, E.; Kotova, A.; Cooper, J. F.; Mitchell, D. G.; Krupp, N.; Paranicas, C.

    2015-10-01

    Radiation belts of MeV protons have been observed just outward of Saturn's main rings. During the final stages of the mission, the Cassini spacecraft will pass through the gap between the main rings and the planet. Based on how the known radiation belts of Saturn are formed, it is expected that MeV protons will be present in this gap and also bounce through the tenuous D ring right outside the gap. At least one model has suggested that the intensity of MeV protons near the planet could be much larger than in the known belts. We model this inner radiation belt using a technique developed earlier to understand Saturn's known radiation belts. We find that the inner belt is very different from the outer belts in the sense that its intensity is limited by the densities of the D ring and Saturn's upper atmosphere, not by radial diffusion and satellite absorption. The atmospheric density is relatively well constrained by EUV occultations. Based on that we predict an intensity in the gap region that is well below that of the known belts. It is more difficult to do the same for the region magnetically connected to the D ring since its density is poorly constrained. We find that the intensity in this region can be comparable to the known belts. Such intensities pose no hazard to the mission since Cassini would only experience these fluxes on timescales of minutes but might affect scientific measurements by decreasing the signal-to-contamination ratio of instruments.

  18. Decay of equatorial ring current ions and associated aeronomical consequences

    NASA Technical Reports Server (NTRS)

    Fok, M.-C.; Kozyra, J. U.; Nagy, A. F.; Rasmussen, C. E.; Khazanov, G. V.

    1993-01-01

    The decay of the major ion species which constitute the ring current is studied by solving the time evolution of their distribution functions during the recovery phase of a moderate geomagnetic storm. In this work, only equatorially mirroring particles are considered. Particles are assumed to move subject to E x B and gradient drifts. They also experience loses along their drift paths. Two loss mechanisms are considered: charge exchange with neutral hydrogen atoms and Coulomb collisions with thermal plasma in the plasmasphere. Thermal plasma densities are calculated with a plasmaspheric model employing a time-dependent convection electric field model. The drift-loss model successfully reproduces a number of important and observable features in the distribution function. Charge exchange is found to be the major loss mechanism for the ring current ions; however the important effects of Coulomb collisions on both the ring current and thermal populations are also presented. The model predicts the formation of a low-energy (less than 500 eV) ion population as a result of energy degradation caused by Coulomb collision of the ring current ions with the plasmaspheric electrons; this population may be one source of the low-energy ions observed during active and quiet periods in the inner magnetosphere. The energy transferred to plasmaspheric electrons through Coulomb collisions with ring current ions is believed to be the energy source for the electron temperature enhancement and the associated 6300 A (stable auroral red (SAR) arc) emission in the subauroral region. The calculated energy deposition rate is sufficient to produce a subauroral electron temperature enhancement and SAR arc emissions that are consistent with observations of these quantities during moderate magnetic activity levels.

  19. Assembling a ring-shaped crystal in a microfabricated surface ion trap

    DOE PAGES

    Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco; Blain, Matthew; Clark, Craig R.; Clark, Susan; Haltli, Raymond A.; Maunz, Peter; Sterk, Jonathan D.; Tigges, Chris

    2015-09-01

    We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca+ ions with an average separation of 9 μm comprise the ion crystal.

  20. Development of the electromagnetically launched expanding ring as a high-strain-rate test technique

    SciTech Connect

    Gourdin, W.H.; Weinland, S.L.; Boling, R.M.

    1989-03-01

    Improvements to the electromagnetically launched expanding ring experiment that make the technique more reproducible, analyzable, and amenable to the rapid testing of many specimens are presented. Aspects of the design and containment of the primary solenoid, high-voltage switching, and electromagnetic diagnostics are discussed, and a new method for launching specimens of low conductivity is described. The reproducibility of the method is demonstrated for oxygen-free electronic (OFE)copper and tantalum rings.