WorldWideScience

Sample records for non-magnetic scuba cylinder

  1. Scuba Club

    CERN Multimedia

    Club subaquatique

    2011-01-01

    Free Trial Dive Ever thought of exploring the surrealistic world of scuba diving? Well, now you can start by joining the CERN Scuba Diving Club. A big activity of the club is to provide training, within the French Federation system, for beginners right through to monitor level. The level 1 course starts this Autumn in the Varembé swimming pool in Geneva. Curious? Then why not come along for a free trial dive in Varembé swimming pool on the 12th or 19th of October 2011. Just bring your swim wear and we will provide the rest. Offer open to adults, minimum age limit 14 years. To sign up, send an email to subaqua@cern.ch

  2. Scuba club

    CERN Multimedia

    Scuba club

    2015-01-01

    The CERN Scuba club will be offering a free trail scuba dive sessions for anyone interested in trying this passionate activity. You don't have to be a daredevil or a great swimmer. Anyone curious to try can have a go. So don't miss the golden opportunity to discover a whole new fascinating world, taking your first breaths underwater! Two separate sessions will be help on Wednesday 7th October and Wednesday 14th October, both starting at 19:00 at the Varembe Swimming pool, 46 Avenue Giuseppe-Motta, 1202 Geneva. To sign up send an email to: subaqua@cern.ch (please indicate which date you wish to attend. You may only attend one). This event is open to adults and young people 14+. Minors must be accompanied by a parent. More information will soon be made available at the club website https://subaqua.web.cern.ch/subaqua/

  3. Scuba club

    CERN Multimedia

    Scuba club

    2014-01-01

    The CERN Scuba club will be offering a free trail scuba dive sessions for anyone interested in trying this passionate activity. You don't have to be a daredevil or a great swimmer. Anyone curious to try can have a go. So don't miss the golden opportunity to discover a whole new fascinating world, taking your first breaths underwater! Two separate sessions will be help on Wednesday 24th September and Wednesday 1st October, both starting at 19:00 at the Varembe Swimming pool, 46 Avenue Giuseppe-Motta, 1202 Geneva. To sign up send an email to: subaqua@cern.ch (please indicate which date you wish to attend. You may only attend one). This event is open to adults and young people 14+. Minors must be accompanied by a parent. More information will soon be made available at the club website https://subaqua.web.cern.ch/subaqua/.

  4. Scuba Club

    CERN Multimedia

    Club subaquatique

    2011-01-01

    Ever thought of exploring the surrealistic world of scuba diving? Well, now you can start by joining the CERN Scuba Diving Club. Since 1963, the CSC has been organising diving trips, lessons and much more to thousands of divers. The main activity of the club is providing training, within the French Federation system, for beginners right through to monitor level. The level 1 course starts this autumn in the Varembé swimming pool in Geneva. Twice a year, the CSC organizes an outing to the Mediterranean. Open to all, the first is usually held in May to finalise the level 1 training while the second, more of a family event, is in the autumn. An excellent atmosphere is guaranteed! Other activities include an underwater photography and video section as well as an underwater biology section. The two are complementary and are animated by qualified and experienced teachers. Curious? Then why not come along for a free trial dive in Varembé swimming pool on the 12th and 19th of October 2011....

  5. Travelers' Health: Scuba Diving

    Science.gov (United States)

    ... 2 - Environmental Hazards Chapter 2 - Medical Tourism Scuba Diving Daniel A. Nord Published estimates report anywhere from ... may include an electrocardiogram and exercise treadmill test. DIVING DISORDERS Barotrauma Ear and sinus Ear barotrauma is ...

  6. CERN Scuba Diving Club

    CERN Multimedia

    Club Subaquatique du CERN

    2017-01-01

    Interested in scuba diving? Fancy a fun trial dive? Like every year, the CERN Scuba Diving Club is organizing two free trial dive sessions. Where? Varembé Swimming Pool, Avenue Giuseppe Motta 46, 1202 Genève When? 25th October and 1st November at 19:15 (one session per participant) Price? Trial dives are FREE! Swimming pool entrance 5,40 CHF. What to bring? Swimwear, towel, shower necessities and a padlock – diving equipment will be provided by the CSC. For more information and to subscribe, follow the link below: http://cern.ch/csc-baptemes-2017 Looking forward to meeting you!

  7. 46 CFR 197.430 - SCUBA diving.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false SCUBA diving. 197.430 Section 197.430 Shipping COAST... GENERAL PROVISIONS Commercial Diving Operations Specific Diving Mode Procedures § 197.430 SCUBA diving. The diving supervisor shall insure that— (a) SCUBA diving is not conducted— (1) Outside the...

  8. 29 CFR 1910.424 - SCUBA diving.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false SCUBA diving. 1910.424 Section 1910.424 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Commercial Diving Operations Specific Operations Procedures § 1910.424 SCUBA diving. (a) General. Employers engaged in SCUBA diving shall comply with the...

  9. 29 CFR 1926.1084 - SCUBA diving.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false SCUBA diving. 1926.1084 Section 1926.1084 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Diving Specific Operations Procedures § 1926.1084 SCUBA diving. Note: The requirements applicable to construction work under this section are identical to...

  10. Introduction to Scuba Diving. Diver Education Series.

    Science.gov (United States)

    Somers, Lee H.

    Scuba diving is often referred to as a "recreational sport." However, the term "sport" sometimes implies erroneous connotations and limits understanding. Scuba diving can be an avocation or a vocation. It is a pastime, a pursuit, or even a lifestyle, that can be as limited or extensive as one makes it. A persons level of commitment, degree of…

  11. Teaching Persons with Disabilities to SCUBA Diving.

    Science.gov (United States)

    Jankowski, Louis W.

    This booklet is designed to sensitize and inform the scuba diving instructor on appropriate attitudes and successful methods for teaching scuba diving to persons with physical disability. It addresses misconceptions about people with disabilities and the importance of effective two-way communication and mutual respect between instructors and…

  12. Ear Disorders in Scuba Divers

    Directory of Open Access Journals (Sweden)

    MH Azizi

    2010-12-01

    Full Text Available History of underwater diving dates back to antiquity. Breath-hold technique in diving was known to the ancient nations. However, deep diving progressed only in the early decades of the 19th century as the result of advancements in efficient underwater technologies which subsequently led to invention of sophisticated sets of scuba diving in the 20th century. Currently, diving is performed for various purposes including commercial, recreational, military, underwater construction, oil industry, underwater archeology and scientific assessment of marine life. By increasing popularity of underwater diving, dive-related medical conditions gradually became more evident and created a new challenge for the health care professionals, so that eventually, a specialty the so-called “diving medicine” was established. Most of the diving-associated disorders appear in the head and neck. The most common of all occupational disorders associated with diving are otologic diseases. External otitis has been reported as the most common otolaryngologic problem in underwater divers. Exostosis of the external ear canal may be formed in divers as the result of prolonged diving in cold waters. Other disorders of the ear and paranasal sinuses in underwater divers are caused by barometric pressure change (i.e., barotraumas, and to a lesser extent by decompression sickness. Barotrauma of the middle ear is the most prevalent barotrauma in divers. The inner ear barotraumas, though important, is less common. The present paper is a brief overview of diving-related ear disorders particularly in scuba divers.

  13. Reducing and Calibrating SCUBA Data on Demand

    Science.gov (United States)

    Jenness, Tim; Bohlender, David A.; Gaudet, Séverin J.; Economou, Frossie; Tilanus, Remo P. J.; Durand, Daniel; Hill, Norman R.

    One of the most important aspects of the new GRID and virtual observatory initiatives is the production of reliably calibrated data from telescope archives. The archive for the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope is small enough (about 100 GB) to allow it to be on-line and for it to be processed in a reasonable amount of time. This makes it possible to address the important issues of calibration and source identification in a dataset that is tractable with reasonable computer hardware. This paper will focus on the JAC's and CADC's experience of automating the processing of SCUBA data, the difficulties and the successes, culminating in the ability of the SCUBA archive at the CADC to serve reduced images on demand.

  14. Scuba Search : when selection meets innovation

    CERN Document Server

    Verel, Sébastien; Clergue, Manuel

    2007-01-01

    We proposed a new search heuristic using the scuba diving metaphor. This approach is based on the concept of evolvability and tends to exploit neutrality in fitness landscape. Despite the fact that natural evolution does not directly select for evolvability, the basic idea behind the scuba search heuristic is to explicitly push the evolvability to increase. The search process switches between two phases: Conquest-of-the-Waters and Invasion-of-the-Land. A comparative study of the new algorithm and standard local search heuristics on the NKq-landscapes has shown advantage and limit of the scuba search. To enlighten qualitative differences between neutral search processes, the space is changed into a connected graph to visualize the pathways that the search is likely to follow.

  15. The evolution of scuba divers pulmonary edema.

    Science.gov (United States)

    Edmonds, Carl

    2016-01-01

    The evolution of scuba divers pulmonary edema is described. When discovered in 1981, it was believed to be a cold-induced response in a submerged, otherwise healthy, scuba diver. The clinical features are described and discussed, as are the demographics. An alleged prevalence of 1.1% was complicated by problematic statistics and an apparent increase in reported cases. Recurrences both while diving and swimming or snorkeling were common. More recent case reports and surveys are described, identifying predisposing factors and associations, including cardiac pathology. Stress cardiomyopathies, reversible myocardial disorder or Takotsubo cardiomyopathy, may complicate the presentation, especially in older females. Relevant cardiac investigations and autopsy findings are reviewed. Disease severity and potential lethality of scuba divers pulmonary edema became more apparent early this century, and these influence our current recommendations to survivors. First aid and treatment are also discussed.

  16. Submillimetre source counts first results from SCUBA

    CERN Document Server

    Mann, R G

    1999-01-01

    The SCUBA submillimetre camera has opened up new possibilities for tracing the evolution of active star formation in dusty galaxies to high redshift, with profound implications for our understanding of the star formation history of the Universe and the contribution from galaxies to the anisotropy of the microwave sky. We review results from several submillimetre surveys started during SCUBA's first year of operation, and discuss their future development, together with other projects that will greatly improve our understanding of the extragalactic point source contribution to the submillimetre sky in the era of MAP and Planck.

  17. Optimized cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials

    Energy Technology Data Exchange (ETDEWEB)

    Yu Zhenzhong; Feng Yijun; Xu Xiaofei; Zhao Junming; Jiang Tian, E-mail: yjfeng@nju.edu.cn [Department of Electronic Engineering, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 (China)

    2011-05-11

    We present optimized design of cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials. Through an optimization procedure based on genetic algorithm, simpler cloak structure and more realizable material parameters can be achieved with better cloak performance than that of an ideal non-magnetic cloak with a reduced set of parameters. We demonstrate that a cloak shell with only five layers of two normal materials can result in an average 20 dB reduction in the scattering width for all directions when covering the inner conducting cylinder with the cloak. The optimized design can substantially simplify the realization of the invisibility cloak, especially in the optical range.

  18. Predictors for the development of temporomandibular disorders in scuba divers

    NARCIS (Netherlands)

    Lobbezoo, F.; van Wijk, A.J.; Klinger, M.C.; Ruiz Vicente, E.; van Dijk, C.J.; Eijkman, M.A.J.

    2014-01-01

    The aim was to determine predictors for the development of complaints of temporomandibular disorders (TMD) in a large sample of Dutch scuba divers who were free of any TMD complaints before they started diving actively. Five-hundred and thirty-six scuba divers (mean ± SD age = 40·4 ± 11·9 years; 34·

  19. [Scuba diving in children: Physiology, risks and recommendations].

    Science.gov (United States)

    Cilveti, R; Osona, B; Peña, J A; Moreno, L; Asensio, O

    2015-12-01

    The increase in recreational scuba diving in recent years, including children, involves risks and the possibility of accidents. While legislation, conditions and risks of scuba diving are well documented in adults, scientific evidence in scuba diving by children and adolescents is sparse and isolated. Furthermore, existing guidelines and recommendations for adults cannot be transferred directly to children. These circumstances have led to the Group on Techniques of the Spanish Society of Pediatric Pulmonology (SENP) to perform a literature search to review and update the knowledge about scuba diving in children. Physiological adaptations of the body are examined during the dive, as well as the anatomical and physiological characteristics of children that should be taken into account in scuba diving. The most common types of accidents and its causes, as well as the risks of scuba diving practice in children with previous diseases are discussed, along with details of the medical and psychological requirements for scuba diving to be considered in the assessment of child and adolescent. A list of recommendations for scuba diving with compressed air in children is presented by a group of experts. Copyright © 2015 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

  20. Scuba Diving and Kinesiology: Development of an Academic Program

    Science.gov (United States)

    Kovacs, Christopher R.; Walter, Daniel

    2015-01-01

    The use of scuba diving as a recreational activity within traditional university instructional programs has been well established. Departments focusing on kinesiology, physical education, or exercise science have often provided scuba diving lessons as part of their activity-based course offerings. However, few departments have developed an…

  1. Scuba Diving and Kinesiology: Development of an Academic Program

    Science.gov (United States)

    Kovacs, Christopher R.; Walter, Daniel

    2015-01-01

    The use of scuba diving as a recreational activity within traditional university instructional programs has been well established. Departments focusing on kinesiology, physical education, or exercise science have often provided scuba diving lessons as part of their activity-based course offerings. However, few departments have developed an…

  2. Scuba diving activates vascular antioxidant system.

    Science.gov (United States)

    Sureda, A; Batle, J M; Ferrer, M D; Mestre-Alfaro, A; Tur, J A; Pons, A

    2012-07-01

    The aim was to study the effects of scuba diving immersion on plasma antioxidant defenses, nitric oxide production, endothelin-1 and vascular endothelial growth factor levels. 9 male divers performed an immersion at 50 m depth for a total time of 35 min. Blood samples were obtained before diving at rest, immediately after diving, and 3 h after the diving session. Leukocyte counts, plasma 8oxoHG, malondialdehyde and nitrite levels significantly increased after recovery. Activities of lactate dehydrogenase, creatine kinase, catalase and superoxide significantly increased immediately after diving and these activities remained high after recovery. Plasma myeloperoxidase activity and protein levels and extracellular superoxide dismutase protein levels increased after 3 h. Endothelin-1 concentration significantly decreased after diving and after recovery. Vascular endothelial growth factor concentration significantly increased after diving when compared to pre-diving values, returning to initial values after recovery. Scuba diving at great depth activated the plasma antioxidant system against the oxidative stress induced by elevated pO₂ oxygen associated with hyperbaria. The decrease in endothelin-1 levels and the increase in nitric oxide synthesis could be factors that contribute to post-diving vasodilation. Diving increases vascular endothelial growth factor plasma levels which can contribute to the stimulation of tissue resistance to diving-derived oxidative damage.

  3. The SCUBA-2 "All-Sky" Survey

    CERN Document Server

    Thompson, M A; Jenness, T; Scott, D; Ashdown, M; Brunt, C; Butner, H; Chapin, E; Chrysostomou, A C; Clark, J S; Clements, D; Collett, J L; Coppin, K; Coulson, I M; Dent, W R F; Economou, F; Evans, A; Friberg, P; Fuller, G A; Gibb, A G; Greaves, J; Hatchell, J; Holland, W S; Hudson, M; Ivison, R J; Jaffe, A; Joncas, G; Jones, H R A; Knapen, J H; Leech, J; Mann, R; Matthews, H E; Moore, T J T; Mortier, A; Negrello, M; Nutter, D; Pestalozzi, M P; Pope, A; Richer, J; Shipman, R; Urquhart, J S; Vaccari, M; Van Waerbeke, L; Viti, S; Weferling, B; White, G J; Wouterloot, J; Zhu, M

    2007-01-01

    The sub-millimetre wavelength regime is perhaps the most poorly explored over large areas of the sky, despite the considerable effort that has been expended in making deep maps over small regions. As a consequence the properties of the sub-millimetre sky as a whole, and of rare bright objects in particular, remains largely unknown. Here we describe a forthcoming survey (the SCUBA-2 ``All-Sky'' Survey, or SASSy) designed to address this issue by making a large-area map of approximately one-fifth of the sky visible from the JCMT (4800 square degrees) down to a 1 sigma noise level of 30 mJy/beam. This map forms the pilot for a much larger survey, which will potentially map the remaining sky visible from the JCMT, with the region also visible to ALMA as a priority. SASSy has been awarded 500 hours for the 4800 square degree pilot phase and will commence after the commissioning of SCUBA-2, expected in early 2008.

  4. Orbital subperiosteal hematoma from scuba diving.

    Science.gov (United States)

    Rosenberry, Clark; Angelidis, Matthew; Devita, Diane

    2010-09-01

    Only a few cases of nontraumatic orbital subperiosteal hematoma due to scuba diving have been reported, and this is the first of such cases that underwent surgical intervention. This injury results from negative pressure within the face mask, suctioning orbital tissues into the mask after incomplete equilibration of pressure on descent. Valsalva maneuver is a second mechanism implicated in the etiology of this injury. Recognition of this injury is of the utmost importance because vision loss is a possible complication if there is compression of the optic nerve or increased intraocular pressure. In many cases of nontraumatic orbital hematoma, conservative management is adequate; however, this case was an exception due to worsening exam findings. Divers may be able to prevent this injury by frequent and gentle equilibration of mask pressure on descent.

  5. B-type natriuretic peptide secretion following scuba diving

    DEFF Research Database (Denmark)

    Passino, Claudio; Franzino, Enrico; Giannoni, Alberto;

    2011-01-01

    To examine the neurohormonal effects of a scuba dive, focusing on the acute changes in the plasma concentrations of the different peptide fragments from the B-type natriuretic peptide (BNP) precursor....

  6. Should children be SCUBA diving?: Cerebral arterial gas embolism in a swimming pool.

    Science.gov (United States)

    Johnson, Valerie; Adkinson, Cheryl; Bowen, Mariya; Ortega, Henry

    2012-04-01

    Cerebral arterial gas embolism (CAGE) is a well-known serious complication of self-contained breathing apparatus (SCUBA) diving. Most serious complications of SCUBA diving occur in adults because most of SCUBA divers are adults. However, young age is an independent risk factor for injury in SCUBA diving and shallow-water SCUBA diving is the riskiest environment for CAGE. We present a case of a 10-year-old boy who developed CAGE while taking SCUBA diving lessons in a university swimming pool. This case illustrates the potential danger of SCUBA diving for children who lack understanding of the physics of diving as well as the often unappreciated risk of shallow-water SCUBA diving. Our intent is to educate providers of primary care to children, so that they may appropriately advise parents about SCUBA diving, and to educate providers of emergency care to children, so that they will recognize this uncommon but serious emergency condition.

  7. The diversity of SCUBA-selected galaxies

    CERN Document Server

    Ivison, R J; Barger, A J; Kneib, J P; Blain, A W; Owen, F; Kerr, T H; Cowie, L L; Ivison, Rob; Smail, Ian; Barger, Amy; Kneib, Jean-Paul; Blain, Andrew; Owen, Frazer; Kerr, Tom; Cowie, Len

    1999-01-01

    We present extensive observations of a sample of distant, submm galaxies detected in the field of the massive cluster lens, A1835, using SCUBA. Taken in conjunction with earlier observations of other submm-selected sources (Ivison et al. 1998; Smail et al. 1999; Soucail et al. 1999) we now have detailed, multi-wavelength observations of 7 examples of the submm population, having exploited the combination of achromatic amplification by cluster lenses and lavish archival datasets. These sources, all clearly at z > 1, illustrate the wide range in the radio and optical properties of distant submm-selected galaxies. We include detailed observations of the first candidate `pure' starburst submm galaxy at high redshift, a z=2.56 interacting galaxy which shows no obvious sign of hosting an AGN. The remaining sources have varying degrees of inferred AGN activity (3 from 7 of the most luminous show some evidence of the presence of an AGN) although even when an AGN is obviously present it is still not apparent if reproc...

  8. UXC55 Non-Magnetic Robot

    CERN Document Server

    Najjar, Tony

    2017-01-01

    As part of the collaboration between CMS and the Lebanese American University, we are looking into building a non-magnetic inspection rover capable of roaming around UXC55 and specifically under the detector. The robot should be specifically tailored and engineered to cope with the strong magnetic field in the cavern (300 G on average with peaks up to 1500 G) as well as other constraints such as flammability and geometry. Moreover, we are also taking part in the development of the instrumentation and wireless communication of the rover. The biggest challenge in setting up a non-magnetic rover lies in the actuation mechanism, in other words, getting it to move; motors are rotary actuators that rely on the concept of a rotor “trying to catch up” to a rotating magnetic field. We quickly realize the complication with using this popular technology; the strong field created by the CMS magnet greatly interferes with the motor, rendering it utterly stalled. Our approach, on the other hand, consists of using compl...

  9. Electrically-Generated Spin Polarization in Non-Magnetic Semiconductors

    Science.gov (United States)

    2016-03-31

    AFRL-AFOSR-VA-TR-2016-0143 Electrically -generated spin polarization in non-magnetic semiconductors Vanessa Sih UNIVERSITY OF MICHIGAN Final Report 03...SUBTITLE (YIP) - Electrically -generated spin polarization in non-magnetic semiconductors 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-12-1-0258 5c...that produced electrically -generated electron spin polarization in non-magnetic semiconductor heterostructures. Electrically -generated electron spin

  10. Predictors for the development of temporomandibular disorders in scuba divers.

    Science.gov (United States)

    Lobbezoo, F; van Wijk, A J; Klingler, M C; Ruiz Vicente, E; van Dijk, C J; Eijkman, M A J

    2014-08-01

    The aim was to determine predictors for the development of complaints of temporomandibular disorders (TMD) in a large sample of Dutch scuba divers who were free of any TMD complaints before they started diving actively. Five-hundred and thirty-six scuba divers (mean ± SD age = 40.4 ± 11.9 years; 34.1% women) completed a specifically developed questionnaire, either online or on paper. Stepwise forward logistic regression analysis was performed to predict the presence of TMD pain, with several potential risk factors as predictors. Four hundred and eighty-five of the 536 respondents were free of any TMD pain before they started diving actively. In this sample, TMD pain was present in 214 persons (44.1%). Four predictors contributed significantly to the presence of TMD pain, viz., clenching (OR = 2.466), warm water (OR = 1.685), biting on the mouthpiece (OR = 1.598), and the quality rating of the mouthpiece (OR = 0.887, that is, a higher rating means a smaller odds of having TMD pain). TMD pain is a common complaint among scuba divers who were free of such complaints before they started diving actively. Clenching, biting on the mouthpiece, and a low rating of the mouthpiece are predictors for the presence of TMD pain in scuba divers, while diving in cold water serves as a protective factor for TMD pain.

  11. Partial dereverberation used to characterize open circuit scuba diver signatures.

    Science.gov (United States)

    Gemba, Kay L; Nosal, Eva-Marie; Reed, Todd R

    2014-08-01

    The use of passive acoustics to detect self-contained underwater breathing apparatus (SCUBA) divers is useful for nearshore and port security applications. While the performance of a detector can be optimized by understanding the signal's spectral characteristics, anechoic recording environments are generally not available or are cost prohibitive. A practical solution is to obtain the source spectra by equalizing the recording with the inverse of the channel's impulse response. This paper presents a dereverberation method for signal characterization that is subsequently applied to four recorded SCUBA configurations. The inverse impulse response is computed in the least-square sense, and partial dereverberation of SCUBA is performed over the 6-18 kHz band. Results indicate that early reflections and late reverberation added as much as 6.8 dB of energy. Mean unadjusted sound pressure levels computed over the 0.3-80 kHz band were 130 ± 5.9 dB re 1 μPa at 1 m. Bubble noise carries a significant amount of the total energy and masks the regulator signatures from 1.3 to 6 kHz, depending on the regulator configuration. While the dereverberation method is applied here to SCUBA signals, it is generally applicable to other sources if the impulse response of the recording environment can be obtained separately.

  12. Nitrogen narcosis and alcohol consumption--a scuba diving fatality.

    Science.gov (United States)

    Michalodimitrakis, E; Patsalis, A

    1987-07-01

    Nitrogen narcosis can cause death among experienced scuba divers. Nitrogen under pressure affects the brain by acting as an anesthetic agent. Furthermore, the consumption of ethanol along with diving will cause the symptoms of nitrogen narcosis to occur at depths less than 30 m. Our case deals with an experienced diver who drank alcoholic beverages before diving and developed symptoms of nitrogen narcosis at a shallow depth. These two conditions contributed to his death by drowning.

  13. How non-magnetic are "non-magnetic" Herbig Ae/Be stars?

    CERN Document Server

    Wade, G A; Catala, C; Bagnulo, S; Landstreet, J D; Flood, J; Böhm, T; Bouret, J -C; Donati, J -F; Folsom, C P; Grunhut, J; Silvester, J

    2007-01-01

    Our recent discovery of magnetic fields in a small number of Herbig Ae/Be stars has required that we survey a much larger sample of stars. From our FORS1 and ESPaDOnS surveys, we have acquired about 125 observations of some 70 stars in which no magnetic fields are detected. Using a Monte Carlo approach, we have performed statistical comparisons of the observed longitudinal fields and LSD Stokes V profiles of these apparently non-magnetic stars with a variety of field models. This has allowed us to derive general upper limits on the presence of dipolar fields in the sample, and to place realistic upper limits on undetected dipole fields which may be present in individual stars. This paper briefly reports the results of the statistical modeling, as well as field upper limits for individual stars of particular interest.

  14. Cylinder monitoring program

    Energy Technology Data Exchange (ETDEWEB)

    Alderson, J.H. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Cylinders containing depleted uranium hexafluoride (UF{sub 6}) in storage at the Department of Energy (DOE) gaseous diffusion plants, managed by Martin Marietta Energy Systems, Inc., are being evaluated to determine their expected storage life. Cylinders evaluated recently have been in storage service for 30 to 40 years. In the present environment, the remaining life for these storage cylinders is estimated to be 30 years or greater. The group of cylinders involved in recent tests will continue to be monitored on a periodic basis, and other storage cylinders will be observed as on a statistical sample population. The program has been extended to all types of large capacity UF{sub 6} cylinders.

  15. Identification of bacteria in scuba divers' rinse tanks.

    Science.gov (United States)

    Washburn, Brian K; Levin, Andrew E; Hennessy, Kristen; Miller, Michael R

    2010-01-01

    Scuba divers typically rinse equipment in communal tanks. Studies show these tanks are contaminated with bacteria, but the types of bacteria have not been studied. We sought to identify bacteria in rinse tanks at a dive facility at San Pedro, Belize, to determine the origin of the bacteria and determine whether the bacteria represented potential threats to human health. The identity of bacteria was investigated using reverse line blot (RLB) assays based on 28 different rDNA probes designed to detect known pathogens of sepsis, as well as by sequencing 23S rDNA from isolates and performing VITEK identification of several isolates. Based on the identities of bacteria in divers' rinse tanks, many likely originate from the ocean, and others likely originate from the divers themselves. None of the bacteria identified would be considered overt human pathogens. However, some of the bacteria found in the tanks are known to be associated with unsanitary conditions and can cause opportunistic infections, which may pose health problems to some individuals. Rinsing scuba equipment in communal tanks has the potential to transmit disease among some divers. Equipment, especially regulators and masks, should be rinsed/cleaned individually and not be placed in communal tanks.

  16. Delamination of Composite Cylinders

    Science.gov (United States)

    Davies, Peter; Carlsson, Leif A.

    The delamination resistance of filament wound glass/epoxy cylinders has been characterized for a range of winding angles and fracture mode ratios using beam fracture specimens. The results reveal that the delamination fracture resistance increases with increasing winding angle and mode II (shear) fraction (GΠ/G). It was also found that interlaced fiber bundles in the filament wound cylinder wall acted as effective crack arresters in mode I loading. To examine the sensitivity of delamina-tion damage on the strength of the cylinders, external pressure tests were performed on filament-wound glass/epoxy composite cylinders with artificial defects and impact damage. The results revealed that the cylinder strength was insensitive to the presence of single delaminations but impact damage caused reductions in failure pressure. The insensitivity of the failure pressure to a single delamination is attributed to the absence of buckling of the delaminated sublaminates before the cylinder wall collapsed. The impacted cylinders contained multiple delaminations, which caused local reduction in the compressive load capability and reduction in failure pressure. The response of glass/epoxy cylinders was compared to impacted carbon reinforced cylinders. Carbon/epoxy is more sensitive to damage but retains higher implosion resistance while carbon/PEEK shows the opposite trend.

  17. Depth refuge and the impacts of SCUBA spearfishing on coral reef fishes.

    Directory of Open Access Journals (Sweden)

    Steven J Lindfield

    Full Text Available In recent decades, spearfishing with SCUBA has emerged as an efficient method for targeting reef fish in deeper waters. However, deeper waters are increasingly recognised as a potential source of refuge that may help sustain fishery resources. We used a combination of historical catch data over a 20-year time period and fishery-independent surveys to investigate the effects of SCUBA spearfishing on coral reef fish populations in the southern Mariana Islands. Two jurisdictions were studied; Guam, where SCUBA spearfishing is practiced, and the nearby Commonwealth of Northern Mariana Islands (CNMI, where SCUBA spearfishing has been banned since 2003. Fishery-independent data were collected using baited remote underwater stereo-video systems (stereo-BRUVs stratified by depth, marine protected area status and jurisdiction. Herbivores (primary consumers dominated spearfishing catches, with parrotfish (scarines and surgeonfish/unicornfish (acanthurids the main groups harvested. However, the large, endangered humphead wrasse (Cheilinus undulatus was the main species by weight landed by SCUBA spearfishers. SCUBA spearfishing was associated with declining size of scarines over time and catches shifting from a dominance of large parrotfishes to a mixed assemblage with increasing proportions of acanthurids. Comparisons between Guam and the nearby CNMI revealed differences in the assemblage of fished species and also greater size of scarines and acanthurids in deep water where SCUBA fishing is banned. These results suggest that SCUBA spearfishing impacts reef fish populations and that the restriction of this fishing method will ensure refuge for fish populations in deeper waters. We recommend a ban on SCUBA spearfishing to preserve or aid the recovery of large, functionally important coral reef species and to improve the sustainability of coral reef fisheries.

  18. Approximation by Cylinder Surfaces

    DEFF Research Database (Denmark)

    Randrup, Thomas

    1997-01-01

    We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...

  19. Barotrauma with extreme pressures in sport: from scuba to skydiving.

    Science.gov (United States)

    Lynch, James H; Deaton, Travis G

    2014-01-01

    The human body is well adapted to dealing with small variations in atmospheric pressure. However when our pursuit of sport and recreation takes us to extreme altitudes or ocean depths, the change in surrounding pressure has the potential to cause significant morbidity. Sports with more extreme changes in atmospheric pressure such as skydiving and scuba diving commonly place the athlete at risk for barotrauma injuries, especially in the middle ear and sinuses. Middle ear barotrauma occurs when a pressure differential develops between the middle ear and the pressure outside of the tympanic membrane. Early symptoms include ear pain, dizziness, and muffled hearing. When extreme pressure gradients are not relieved, middle ear effusions and rupture of the tympanic membrane can occur. A similar mechanism and injury pattern occurs in the sinuses as well. With proper training and prevention strategies, athletes in these sports can protect themselves from most barotrauma injuries.

  20. Are recreational SCUBA divers with asthma at increased risk?

    DEFF Research Database (Denmark)

    Ustrup, Amalie; Ulrik, Charlotte Suppli

    2016-01-01

    in divers suffering from asthma, obtained from anonymous questionnaires in diving magazines, reported no diving-related injuries among respondents. CONCLUSION: Due to limited evidence difficult to draw valid conclusions, but there are indications that recreational divers with asthma may be at increased risk......BACKGROUND AND OBJECTIVE: Asthma has traditionally been regarded as a contraindication to Self-Contained Underwater Breathing Apparatus (SCUBA) diving, although large numbers of patients with asthma dive. The aim of the present review is to provide an update on current knowledge on potential...... disease-related hazards in SUBA-divers with asthma. METHODS: Systematic literature review based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. RESULTS: Seven studies met the criteria for inclusion in the present review (comprising a total of 560 subjects...

  1. A SCUBA survey of the NGC 2068/2071 protoclusters

    CERN Document Server

    Motte, F; Ward-Thompson, D; Bontemps, S

    2001-01-01

    We report the results of a submillimeter dust continuum survey of the protoclusters NGC 2068 and NGC 2071 in Orion B carried out at 850 microns and 450 microns with SCUBA on JCMT. The mapped region is ~ 32' x 18' in size (~ 4 pc x 2 pc) and consists of filamentary dense cores which break up into small-scale (~ 5000 AU) fragments, including 70 starless condensations and 5 circumstellar envelopes/disks. The starless condensations, seen on the same spatial scales as protostellar envelopes, are likely to be gravitationally bound and pre-stellar in nature. Their mass spectrum, ranging from ~ 0.3 Msun to ~ 5 Msun, is reminiscent of the stellar initial mass function (IMF). Their mass-size relation suggests that they originate from gravitationally-driven fragmentation. We thus argue that pre-collapse cloud fragmentation plays a major role in shaping the IMF.

  2. Estimating the risk of a scuba diving fatality in Australia.

    Science.gov (United States)

    Lippmann, John; Stevenson, Christopher; McD Taylor, David; Williams, Jo

    2016-12-01

    There are few data available on which to estimate the risk of death for Australian divers. This report estimates the risk of a scuba diving fatality for Australian residents, international tourists diving in Queensland, and clients of a large Victorian dive operator. Numerators for the estimates were obtained from the Divers Alert Network Asia-Pacific dive fatality database. Denominators were derived from three sources: Participation in Exercise, Recreation and Sport Surveys, 2001-2010 (Australian resident diving activity data); Tourism Research Australia surveys of international visitors to Queensland 2006-2014 and a dive operator in Victoria 2007-2014. Annual fatality rates (AFR) and 95% confidence intervals (95% CI) were calculated using an exact binomial test. Estimated AFRs were: 0.48 (0.37-0.59) deaths per 100,000 dives, or 8.73 (6.85-10.96) deaths per 100,000 divers for Australian residents; 0.12 (0.05-0.25) deaths per 100,000 dives, or 0.46 (0.20-0.91) deaths per 100,000 divers for international visitors to Queensland; and 1.64 (0.20-5.93) deaths per 100,000 dives for the dive operator in Victoria. On a per diver basis, Australian residents are estimated to be almost twenty times more likely to die whilst scuba diving than are international visitors to Queensland, or to lower than fourfold on a per dive basis. On a per dive basis, divers in Victoria are fourteen times more likely to die than are Queensland international tourists. Although some of the estimates are based on potentially unreliable denominator data extrapolated from surveys, the diving fatality rates in Australia appear to vary by State, being considerably lower in Queensland than in Victoria. These estimates are similar to or lower than comparable overseas estimates, although reliability of all such measurements varies with study size and accuracy of the data available.

  3. Tandem Cylinder Noise Predictions

    Science.gov (United States)

    Lockhard, David P.; Khorrami, Mehdi R.; CHoudhari, Meelan M.; Hutcheson, Florence V.; Brooks, Thomas F.; Stead, Daniel J.

    2007-01-01

    In an effort to better understand landing-gear noise sources, we have been examining a simplified configuration that still maintains some of the salient features of landing-gear flow fields. In particular, tandem cylinders have been studied because they model a variety of component level interactions. The present effort is directed at the case of two identical cylinders spatially separated in the streamwise direction by 3.7 diameters. Experimental measurements from the Basic Aerodynamic Research Tunnel (BART) and Quiet Flow Facility (QFF) at NASA Langley Research Center (LaRC) have provided steady surface pressures, detailed off-surface measurements of the flow field using Particle Image Velocimetry (PIV), hot-wire measurements in the wake of the rear cylinder, unsteady surface pressure data, and the radiated noise. The experiments were conducted at a Reynolds number of 166 105 based on the cylinder diameter. A trip was used on the upstream cylinder to insure a fully turbulent shedding process and simulate the effects of a high Reynolds number flow. The parallel computational effort uses the three-dimensional Navier-Stokes solver CFL3D with a hybrid, zonal turbulence model that turns off the turbulence production term everywhere except in a narrow ring surrounding solid surfaces. The current calculations further explore the influence of the grid resolution and spanwise extent on the flow and associated radiated noise. Extensive comparisons with the experimental data are used to assess the ability of the computations to simulate the details of the flow. The results show that the pressure fluctuations on the upstream cylinder, caused by vortex shedding, are smaller than those generated on the downstream cylinder by wake interaction. Consequently, the downstream cylinder dominates the noise radiation, producing an overall directivity pattern that is similar to that of an isolated cylinder. Only calculations based on the full length of the model span were able to

  4. Beneath the surface : towards improved management of the scuba diving tourism system in Tofo, Mozambique

    OpenAIRE

    2016-01-01

    Natural resource management is essential in areas where livelihoods depend on them. Scuba diving tourism has become one of the fastest growing markets for special interest tourism in the world. Coral degradation and species disappearance poses a great risk for livelihoods in areas where SCUBA diving tourism is the main economic driver. Praia do Tofo emerged as a diving destination thanks to the year round presence of captivating marine mega fauna species: manta rays and whale sharks. Concerns...

  5. Antennas on circular cylinders

    DEFF Research Database (Denmark)

    Knudsen, H. L.

    1959-01-01

    antenna in a circular cylinder. By a procedure similar to the one used by Silver and Saunders, expressions have been derived for the field radiated from an arbitrary surface current distribution on a cylinder surface coaxial with a perfectly conducting cylinder. The cases where the space between the two...... cylindrical surfaces have the sane characteristic constants and different constants are treated separately. Extensive numerical computations of the field radiated from the slot antennas described here are being carried out, but no numerical results are yet available...

  6. Recreational scuba diving: negative or positive effects of oxidative and cardiovascular stress?

    Science.gov (United States)

    Perovic, Antonija; Unic, Adriana; Dumic, Jerka

    2014-01-01

    Environmental conditions and increased physical activity during scuba diving are followed by increased production of free radicals and disturbed redox balance. Redox balance disorder is associated with damage of cellular components, changes of cellular signaling pathways and alterations of gene expression. Oxidative stress leads to increased expression of sirtuins (SIRTs), molecules which play an important role in the antioxidant defense, due to their sensitivity to the changes in the redox status and their ability to regulate redox homeostasis. These facts make SIRTs interesting to be considered as molecules affected by scuba diving and in that sense, as potential biomarkers of oxidative status or possible drug targets in reduction of reactive oxygen species (ROS) accumulation. In addition, SIRTs effects through currently known targets make them intriguing molecules which can act positively on health in general and whose expression can be induced by scuba diving.A demanding physical activity, as well as other circumstances present in scuba diving, has the greatest load on the cardiovascular function (CV). The mechanisms of CV response during scuba diving are still unclear, but diving-induced oxidative stress and the increase in SIRTs expression could be an important factor in CV adaptation. This review summarizes current knowledge on scuba diving-induced oxidative and CV stress and describes the important roles of SIRTs in the (patho)physiological processes caused by the redox balance disorder.

  7. Approximation by Cylinder Surfaces

    DEFF Research Database (Denmark)

    Randrup, Thomas

    1997-01-01

    We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...... projection of the surface onto this plane, a reference curve is determined by use of methods for thinning of binary images. Finally, the cylinder surface is constructed as follows: the directrix of the cylinder surface is determined by a least squares method minimizing the distance to the points...... in the projection within a tolerance given by the reference curve, and the rulings are lines perpendicular to the projection plane. Application of the method in ship design is given....

  8. Underwater Acoustic Source Localisation Among Blind and Sighted Scuba Divers

    Science.gov (United States)

    Cambi, Jacopo; Livi, Ludovica; Livi, Walter

    2017-01-01

    Objectives Many blind individuals demonstrate enhanced auditory spatial discrimination or localisation of sound sources in comparison to sighted subjects. However, this hypothesis has not yet been confirmed with regards to underwater spatial localisation. This study therefore aimed to investigate underwater acoustic source localisation among blind and sighted scuba divers. Methods This study took place between February and June 2015 in Elba, Italy, and involved two experimental groups of divers with either acquired (n = 20) or congenital (n = 10) blindness and a control group of 30 sighted divers. Each subject took part in five attempts at an under-water acoustic source localisation task, in which the divers were requested to swim to the source of a sound originating from one of 24 potential locations. The control group had their sight obscured during the task. Results The congenitally blind divers demonstrated significantly better underwater sound localisation compared to the control group or those with acquired blindness (P = 0.0007). In addition, there was a significant correlation between years of blindness and underwater sound localisation (P sound in an underwater environment. As the correct localisation of sounds underwater may help individuals to avoid imminent danger, divers should perform sound localisation tests during training sessions. PMID:28690888

  9. Nuclear conversion theory: molecular hydrogen in non-magnetic insulators

    Science.gov (United States)

    Ilisca, Ernest; Ghiglieno, Filippo

    2016-09-01

    The hydrogen conversion patterns on non-magnetic solids sensitively depend upon the degree of singlet/triplet mixing in the intermediates of the catalytic reaction. Three main `symmetry-breaking' interactions are brought together. In a typical channel, the electron spin-orbit (SO) couplings introduce some magnetic excitations in the non-magnetic solid ground state. The electron spin is exchanged with a molecular one by the electric molecule-solid electron repulsion, mixing the bonding and antibonding states and affecting the molecule rotation. Finally, the magnetic hyperfine contact transfers the electron spin angular momentum to the nuclei. Two families of channels are considered and a simple criterion based on the SO coupling strength is proposed to select the most efficient one. The denoted `electronic' conversion path involves an emission of excitons that propagate and disintegrate in the bulk. In the other denoted `nuclear', the excited electron states are transients of a loop, and the electron system returns to its fundamental ground state. The described model enlarges previous studies by extending the electron basis to charge-transfer states and `continui' of band states, and focuses on the broadening of the antibonding molecular excited state by the solid conduction band that provides efficient tunnelling paths for the hydrogen conversion. After working out the general conversion algebra, the conversion rates of hydrogen on insulating and semiconductor solids are related to a few molecule-solid parameters (gap width, ionization and affinity potentials) and compared with experimental measures.

  10. SCUBA-2: The 10000 pixel bolometer camera on the James Clerk Maxwell Telescope

    CERN Document Server

    Holland, W S; Chapin, E L; Chrysostomou, A; Davis, G R; Dempsey, J T; Duncan, W D; Fich, M; Friberg, P; Halpern, M; Irwin, K D; Jenness, T; Kelly, B D; MacIntosh, M J; Robson, E I; Scott, D; Ade, P A R; Atad-Ettedgui, E; Berry, D S; Craig, S C; Gao, X; Gibb, A G; Hilton, G C; Hollister, M I; Kycia, J B; Lunney, D W; McGregor, H; Montgomery, D; Parkes, W; Tilanus, R P J; Ullom, J N; Walther, C A; Walton, A J; Woodcraft, A L; Amiri, M; Atkinson, D; Burger, B; Chuter, T; Coulson, I M; Doriese, W B; Dunare, C; Economou, F; Niemack, M D; Parsons, H A L; Reintsema, C D; Sibthorpe, B; Smail, I; Sudiwala, R; Thomas, H S

    2013-01-01

    SCUBA-2 is an innovative 10000 pixel bolometer camera operating at submillimetre wavelengths on the James Clerk Maxwell Telescope (JCMT). The camera has the capability to carry out wide-field surveys to unprecedented depths, addressing key questions relating to the origins of galaxies, stars and planets. With two imaging arrays working simultaneously in the atmospheric windows at 450 and 850 microns, the vast increase in pixel count means that SCUBA-2 maps the sky 100-150 times faster than the previous SCUBA instrument. In this paper we present an overview of the instrument, discuss the physical characteristics of the superconducting detector arrays, outline the observing modes and data acquisition, and present the early performance figures on the telescope. We also showcase the capabilities of the instrument via some early examples of the science SCUBA-2 has already undertaken. In February 2012, SCUBA-2 began a series of unique legacy surveys for the JCMT community. These surveys will take 2.5 years and the ...

  11. A rare case of a scuba diver's death due to propeller injuries of a desalination pump.

    Science.gov (United States)

    Perilli, G; Di Battista, B; Montana, A; Pavia, J; Cauchi, S; Zerafa, N M; Pomara, C

    2015-05-01

    Water skiing, boat racing, skin and scuba diving, as well as pleasure boat cruising are becoming increasingly popular hobbies. As a result, the incidence of injuries secondary to motor propellers is becoming more frequent. Injuries by propellers, amputation, death by drowning, and bleeding are rare reported events in forensic literature. The most common circumstances surrounding boat-propeller-related injuries are concerned with getting into or out of the boat, personal watercraft use or water skiing, and falling or being thrown from the boat. A case of a scuba diver's death that occurred during an illegal scuba fishing trip around a desalination plant is presented. A complete autopsy and histological study of all organs and surfaces of dismembered cadaveric sections, performed in order to determine the phases of death, are reported. An underwater scene investigation was conducted by an engineering team studying the mouth of the pump and the dynamic characteristic of rotating propeller blades.

  12. A case of anterior cerebral artery dissection caused by scuba diving.

    Science.gov (United States)

    Fukuoka, Takuya; Kato, Yuji; Ohe, Yasuko; Deguchi, Ichiro; Maruyama, Hajime; Hayashi, Takeshi; Tanahashi, Norio

    2014-08-01

    A 51-year-old man was admitted with right hemiparesis during scuba diving, without headache. Brain magnetic resonance (MR) imaging depicted high-intensity areas in the left superior frontal and cingulate gyri on diffusion-weighted imaging. Dissection of the anterior cerebral artery (ACA) was detected using axial MR angiography and 3-dimensional MR cisternography. Dissection of the ACA during and after scuba diving has not been reported before. Dissection of the arteries should be included in the differential diagnosis when neurologic symptoms occur both during and after scuba diving, even if the patient does not experience headache. Furthermore, the combination of MR cisternography and MR angiography is useful to detect ACA dissection.

  13. SCUBA A submillimetre camera operating on the James Clerk Maxwell Telescope

    CERN Document Server

    Holland, W S; Gear, W K; Jenness, T; Laidlaw, K; Lightfoot, J F; Robson, E I; Holland, Wayne S.; Cunningham, Colin R.; Gear, Walter K.; Jenness, Tim; Laidlaw, Ken; Lightfoot, John F.

    1998-01-01

    The Submillimetre Common-User Bolometer Array (SCUBA) is one of a new generation of cameras designed to operate in the submillimetre waveband. The instrument has a wide wavelength range covering all the atmospheric transmission windows between 300 and 2000 microns. In the heart of the instrument are two arrays of bolometers optimised for the short (350/450 microns) and long (750/850 microns) wavelength ends of the submillimetre spectrum. The two arrays can be used simultaneously, giving a unique dual-wavelength capability, and have a 2.3 arc-minute field of view on the sky. Background-limited performance is achieved by cooling the arrays to below 100 mK. SCUBA has now been in active service for over a year, and has already made substantial breakthroughs in many areas of astronomy. In this paper we present an overview of the performance of SCUBA during the commissioning phase on the James Clerk Maxwell Telescope (JCMT).

  14. Sphenoidal sinus mucocele presenting with acute visual loss in a scuba diver

    Science.gov (United States)

    Mowatt, Lizette; Foster, Tecah

    2013-01-01

    A 43-year-old male scuba diver presented with an acute history of painful unilateral visual loss after scuba diving. He had right-sided retrobulbar pain and headache. He was known to have sinusitis and had transient visual loss in two previous episodes after scuba diving. His visual acuity was hand motions and 20/20 in the right and left eye, respectively. There was no proptosis. He had a right relative afferent pupillary defect. Colour vision was normal in the left eye and absent in the right eye. Fundal examination revealed healthy discs and macula bilaterally. He was assessed as a right optic neuropathy, possibly secondary to compression. An MRI of the brain revealed a large sphenoidal mucocele extending into the right optic foramen. He was treated with oral steroids, antibiotics and nasal decongestants. He underwent endoscopic intranasal sphenoidectomy and marsupialisation with return of his visual acuity to 20/25 in that eye. PMID:23964041

  15. Rolling Cylinder Phase 1

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Taraborrelli, Valeria Taraborrelli

    Margheritini and Valeria Taraborrelli(valeria.taraborrelli@hotmail.it) with a total of 3 day visit from the developers. Laboratory tests in irregular waves will be performed by Lucia Margheritini. The report is aimed at the first stage testing of the Rolling Cylinder wave energy device. This phase includes...

  16. EPO modulation in a 14-days undersea scuba dive.

    Science.gov (United States)

    Revelli, L; Vagnoni, S; D'Amore, A; Di Stasio, E; Lombardi, C P; Storti, G; Proietti, R; Balestra, C; Ricerca, B M

    2013-10-01

    Erythropoiesis is affected during deep saturation dives. The mechanism should be related to a downregulation of serum Erythropoietin (s-EPO) concentration or to a toxic effect of the hyperbaric hyperoxia. We evaluated s-EPO and other haematological parameters in 6 scuba divers before, during and after a 14-days guinness saturation dive (8-10 m). Athletes were breathing air at 1.8-2 ATA, under the control of a team of physicians. Serum parameters were measured before diving (T0) and: 7 days (T1), 14 days (T2) after the beginning of the dive and 2 h (T3) and 24 h (T4) after resurfacing. Hgb, and many other haematological parameters did not change whereas Ht, s-EPO, the ratio between s-EPO predicted and that observed and reticulocytes (absolute, percent) declined progressively from T0 to T3. At T4 a significant rise in s-EPO was observed. Hgb did not vary but erythropoiesis seemed to be affected as s-EPO and reticulocyte counts showed. All these changes were statistically significant. The experiment, conducted in realistic conditions of dive length, oxygen concentration and pressure, allows us to formulate some hypotheses about the role of prolonged hyperbarism on erythropoiesis. The s-EPO rise, 24 h after resurfacing, is clearly documented and related to the "Normobaric Oxygen Paradox". This evidence suggests interesting hypotheses for new clinical applications such as modulation of s-EPO production and Hgb content triggered by appropriate O₂ administration in pre-surgical patients or in some anemic disease.

  17. Magnetic Nanoparticles in Non-magnetic CNTs and Graphene

    Science.gov (United States)

    Kayondo, Moses; Seifu, Dereje

    Magnetic nanoparticles were embedded in non-magnetic CNTs and graphene matrix to incorporate all the advantages and the unique properties of CNTs and graphene. Composites of CNTs and graphene with magnetic nanoparticles may offer new opportunities for a wide variety of potential applications such as magnetic data storage, magnetic force microscopy tip, electromagnetic interference shields, thermally conductive films, reinforced polymer composites, transparent electrodes for displays, solar cells, gas sensors, magnetic nanofluids, and magnetically guided drug delivery systems. Magnetic nanoparticles coated CNTs can also be used as an electrode in lithium ion battery to replace graphite because of the higher theoretical capacity. Graphene nanocomposites, coated with magnetic sensitive nanoparticles, have demonstrated enhanced magnetic property. We would like to acknowledge support by NSF-MRI-DMR-1337339.

  18. THE EXPERIMENT WITH FARADAY CYLINDER

    Institute of Scientific and Technical Information of China (English)

    薛英

    2004-01-01

    Suppose there are two electricity testers, A and B(Figure A) . And a metal cylinder C which is almost closed (called Faraday Cylinder)is fixed to tester B, making both tester B and cylinder C charged. As a result, the aluminium foil on tester B opens.

  19. Akari, SCUBA2 and Herschel data of pre-stellar cores

    CERN Document Server

    Ward-Thompson, Derek; Kirk, Jason Matthew; André, Philippe; Di Francesco, James

    2015-01-01

    We show Akari data, Herschel data and data from the SCUBA2 camera on JCMT, of molecular clouds. We focus on pre-stellar cores within the clouds. We present Akari data of the L1147-1157 ring in Cepheus and show how the data indicate that the cores are being externally heated. We present SCUBA2 and Herschel data of the Ophiuchus region and show how the environment is also affecting core evolution in this region. We discuss the effects of the magnetic field in the Lupus I region, and how this lends support to a model for the formation and evolution of cores in filamentary molecular clouds.

  20. A new era of wide-field submillimetre imaging: on-sky performance of SCUBA-2

    OpenAIRE

    Dempsey, Jessica T.; Holland, Wayne S.; Chrysostomou, Antonio; Berry, David S.; Bintley, Daniel; Chapin, Edward L.; Craig, Simon C.; Coulson, Iain M.; Davis, Gary R.; Friberg, Per; Jenness, Tim; Gibb, Andy G.; Parsons, Harriet A. L.; Scott, Douglas; Thomas, Holly S.

    2012-01-01

    SCUBA-2 is the largest submillimetre wide-field bolometric camera ever built. This 43 square arc-minute field-of-view instrument operates at two wavelengths (850 and 450 microns) and has been installed on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. SCUBA-2 has been successfully commissioned and operational for general science since October 2011. This paper presents an overview of the on-sky performance of the instrument during and since commissioning in mid-2011. The on-sky noise ...

  1. Dropwise Condensation on Hydrophobic Cylinders

    CERN Document Server

    Park, Kyoo-Chul; Hoang, Michelle; McManus, Brendan; Aizenberg, Joanna

    2016-01-01

    In this work, we studied the effect of the diameter of horizontal hydrophobic cylinders on droplet growth. We postulate that the concentration gradient created by natural convection around a horizontal circular cylinder is related to the droplet growth on the cylinder by condensation. We derive a simple scaling law of droplet growth and compare it with experimental results. The predicted negative exponent of drop diameter (d) as a function of cylinder diameter (D) at different time points is similar to the general trend of experimental data. Further, this effect of cylinder diameter on droplet growth is observed to be stronger than the supersaturation conditions created by different surface temperatures.

  2. Performance of the SCUBA-2 dry dilution refrigerator: 4 years of operation at the JCMT

    Science.gov (United States)

    Bintley, Dan; Kuroda, John T.; Starman, Erik G.; Craig, Simon; Holland, Wayne S.

    2012-09-01

    Cryogen free or ‘dry’ dilution refrigerators that integrate a cryocooler such as a two stage pulse tube to replace the conventional liquid helium bath and 1K pot, have become a practical alternative for cooling astronomical detectors to mK temperatures and offer many advantages. SCUBA-2, the new submillimetre camera in operation at the JCMT, on the summit of Mauna Kea, Hawaii, was one of the first instruments to use such a fridge design. The dry dilution fridge for SCUBA-2 has now been in service for almost 4 years during commissioning at JCMT. In the most recent astronomical commissioning phase, the dilution fridge was in continuous operation for 10 months with no loss of base temperature or cooling power, cooling the SCUBA-2 detector arrays to below 100mK while maintaining a further 100Kg of enclosure, shields and SQUID amplifiers at 1K. In this paper we review some of the lessons from operating a dry dilution fridge at the JCMT and the necessary changes that have been incorporated. We present the performance of the fridge and discus its role in ensuring the success of SCUBA-2.

  3. Temporomandibular disorders in scuba divers-an increased risk during diving certification training.

    Science.gov (United States)

    Oztürk, Ozmen; Tek, Mustafa; Seven, Hüseyin

    2012-11-01

    The design of a diving regulator's mouthpiece increases the risk of a temporomandibular disorder (TMD) in scuba divers. The total weight of a diving regulator is reflected directly on the temporomandibular joint, causing articular and periarticular disorders. In the current study, the prevalence of TMD in scuba divers triggered during diving certification training is investigated. We also aimed to determine the factors that lead to TMD during diving training and clarify the observation that there is an increased incidence of TMD in inexperienced divers. The study was held between 2006 and 2011. Ninety-seven divers were referred with the complaint of pain around temporomandibular area. The divers were classified according to their diving experience. Symptoms and signs of TMD were graded. Fourteen divers were diagnosed with TMD. Temporomandibular disorder was seen more frequently in inexperienced divers than in experienced divers (P = 0.0434). The most prevalent symptom was an increased effort for mouthpiece gripping. Temporomandibular joint tenderness and trigger point activation were the mostly seen physical signs. Thirteen divers had an improvement with therapy. The increased effort for stabilizing the mouthpiece is a recognized factor in TMD development. Attention must be paid to an association of scuba diving with TMDs, especially in inexperienced divers having a scuba certification training.

  4. Construction of Tests in the Cognitive and Psychomotor Domains for Skin and Scuba Diving.

    Science.gov (United States)

    McCarthy, Jean

    The fundamental purposes of this study were to develop mastery tests in the cognitive and psychomotor domains for skin and scuba diving and to establish validity and reliability for the tests. A table of specifications was developed for each domain, and a pilot study refined the initial test batteries into their final form. In the main study,…

  5. Giant spin Seebeck effect in a non-magnetic material.

    Science.gov (United States)

    Jaworski, C M; Myers, R C; Johnston-Halperin, E; Heremans, J P

    2012-07-11

    The spin Seebeck effect is observed when a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material, where it gets converted into a measurable voltage. It has been previously observed with a magnitude of microvolts per kelvin in magnetically ordered materials, ferromagnetic metals, semiconductors and insulators. Here we describe a signal in a non-magnetic semiconductor (InSb) that has the hallmarks of being produced by the spin Seebeck effect, but is three orders of magnitude larger (millivolts per kelvin). We refer to the phenomenon that produces it as the giant spin Seebeck effect. Quantizing magnetic fields spin-polarize conduction electrons in semiconductors by means of Zeeman splitting, which spin-orbit coupling amplifies by a factor of ∼25 in InSb. We propose that the giant spin Seebeck effect is mediated by phonon-electron drag, which changes the electrons' momentum and directly modifies the spin-splitting energy through spin-orbit interactions. Owing to the simultaneously strong phonon-electron drag and spin-orbit coupling in InSb, the magnitude of the giant spin Seebeck voltage is comparable to the largest known classical thermopower values.

  6. A PORTABLE DENTAL STERILIZING CYLINDER

    Science.gov (United States)

    The report describes an aluminum cylinder in which dental instruments could be sterilized under emergency field conditions and at the same time be...protected against corrosion. The procedure involves loading the cylinder with dental instruments, flushing it with ethylene oxide-Freon gas, closing it...and then immersing it in boiling water for l hour. In preliminary experiments with a prototype of the sterilizing cylinder, dental instruments were

  7. Brain magnetic resonance imaging, aerobic power, and metabolic parameters among 30 asymptomatic scuba divers.

    Science.gov (United States)

    Tripodi, D; Dupas, B; Potiron, M; Louvet, S; Geraut, C

    2004-11-01

    The aim of the study was to evaluate the presence of cerebral lesions in asymptomatic scuba divers and explain the causes of them: potential risk factors associating cardiovascular risk factors, low aerobic capacity, or characteristics of diving (maximum depth, ascent rate). Experienced scuba divers, over 40 years of age, without any decompression sickness (DCS) history were included. We studied 30 scuba divers (instructors) without any clinical symptoms. For all of them, we carried out a clinical examination with fatty body mass determination and we questioned them about their diving habits. A brain Magnetic Resonance imaging (MRI), an assessment of maximal oxygen uptake, glycemia, triglyceridemia, and cholesterolemia were systematically carried out. Cerebral spots of high intensity were found at 33 % in the scuba diving group and 30 % in the control group. In the diving group, abnormalities were related to unsafe scuba-diving or metabolic abnormalities. In our study, we did not find a significant relationship between the lesions of the central nervous system, and the age, depth of the dives, number of dives, and ergometric performances (maximal oxygen uptake, V.O (2max), serum level of blood lactate). Nevertheless, we found a significant relationship between the lesions of the central nervous system and ascent rate faster than 10 meters per minute (r = 0.57; p = 0.003) or presence of high level of cholesterolemia (r = 0.6; p = 0.001). We found concordant results using the Cochran's Test: meaningful link between the number of brain lesions and the speed of decompression (Uexp = 14 < Utable = 43; alpha = 0.05, p < 0.01). We concluded that hyperintensities can be explained by preformed nitrogen gas microbubbles and particularly in presence of cholesterol, when the ascent rate is up to 10 meters per minute. So, it was remarkable to note that asymptomatic patients practicing scuba diving either professionally or recreationally, presented lesions of the central nervous

  8. Rolling Cylinder Phase 1bis

    DEFF Research Database (Denmark)

    Margheritini, Lucia

    Cylinder Phase 1: proof of concept and first optimization”, DCE report 115, ISSN 1901-726X, and it is recommended that the two are consulted together as they were firstly agreed to be in one document. The present report aims at estimate the efficiency of the Rolling Cylinder long model (previously...

  9. Natural convection from circular cylinders

    CERN Document Server

    Boetcher, Sandra K S

    2014-01-01

    This book presents a concise, yet thorough, reference for all heat transfer coefficient correlations and data for all types of cylinders: vertical, horizontal, and inclined. This book covers all natural convection heat transfer laws for vertical and inclined cylinders and is an excellent resource for engineers working in the area of heat transfer engineering.

  10. Approximation of Surfaces by Cylinders

    DEFF Research Database (Denmark)

    Randrup, Thomas

    1998-01-01

    We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...

  11. Funding conservation through use and potentials for price discrimination among scuba divers at Sipadan, Malaysia.

    Science.gov (United States)

    Emang, Diana; Lundhede, Thomas Hedemark; Thorsen, Bo Jellesmark

    2016-11-01

    The protected coral reefs off the coast of Malaysia receive numerous tourists, while also being as fishing grounds. These joint environmental pressures raise the need for additional costly conservation measures. It is natural to consider the potential for expanding the 'user pays' principle, already implemented in the form of various user fees. This study explores the potential for price discrimination among scuba divers at Sipadan in Malaysia. The study applies a choice experiment to estimate scuba divers willingness to pay higher user fees for avoiding decreases of or getting improvements in environmental and recreational aspects of the diving experience. We investigate how sensitivity to fee size and hence willingness to pay vary with suitable selected characteristics of divers. We find potentials for a third degree price discrimination strategy exploiting higher willingness to pay among foreign divers (45%), male divers (16%) and people who has visited Sipadan several times (25%). Thus, revised pricing structures could significantly increase funds for the preservation of Sipadan.

  12. The Effects of Teaching Coping Strategies on the Performance of Beginning Scuba Divers.

    Science.gov (United States)

    1983-04-07

    biofeedback group, a .- • o . , .- - , ,, • - , -- - - . - • , . - r -, , - 3 meditation group, and a control group. Diver’s performance was...randomly assigned to a bio-feedback group, a meditation group, or a control group. The STAI was administered, and some physiological measures were taken...scuba diving classes to one of three groups (a bio-feedback group, a meditation group, or a control group). They administered the STAI to gain baseline

  13. Effects of recreational scuba diving on Mediterranean fishes: evidence of involuntary feeding?

    Directory of Open Access Journals (Sweden)

    A. DI FRANCO

    2013-04-01

    Full Text Available Despite a large body of literature assessing the impacts of recreational scuba diving on marine habitats, little attention has been paid to the potentially harmful effects this has on fishes. The aim of this study was the assessment of the immediate response of different fish species to divers’ activities. A decrease of fishes’ natural diffidence towards divers is shown, probably due to an enhanced availability of their prey as a result of divers’ contacts with the substrate.

  14. Scalar cylinder-plate and cylinder-cylinder Casimir interaction in higher dimensional spacetime

    CERN Document Server

    Teo, L P

    2015-01-01

    We study the cylinder-plate and the cylinder-cylinder Casimir interaction in the $(D+1)$-dimensional Minkowski spacetime due to the vacuum fluctuations of massless scalar fields. Different combinations of Dirichlet (D) and Neumann (N) boundary conditions are imposed on the two interacting objects. For the cylinder-cylinder interaction, we consider the case where one cylinder is inside the other, and the case where the two cylinders are outside each other. By computing the transition matrices of the objects and the translation matrices that relate different coordinate systems, the explicit formulas for the Casimir interaction energies are derived. Using perturbation technique, we compute the small separation asymptotic expansions of the Casimir interaction energies up to the next-to-leading order terms. The leading terms coincide with the respective results obtained using proximity force approximation, which is of order $d^{-D+1/2}$, where $d$ is the distance between the two objects. The results on the next-to...

  15. Approximation of Surfaces by Cylinders

    DEFF Research Database (Denmark)

    Randrup, Thomas

    1998-01-01

    We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...... projection of the surface onto this plane, a reference curve is determined by use of methods for thinning of binary images. Finally, the cylinder surface is constructed as follows: the directrix of the cylinder surface is determined by a least squares method minimizing the distance to the points...... in the projection within a tolerance given by the reference curve, and the rulings are lines perpendicular to the projection plane. Application of the method in ship design is given....

  16. Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors.

    Science.gov (United States)

    Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V

    2015-07-03

    The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm(2) cross-section. The impurities suppress superconductivity in a three-dimensional 'Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.

  17. SCUBA-2 instrument: an application of large-format superconducting bolometer arrays for submillimetre astronomy

    Science.gov (United States)

    Hollister, Matthew Ian

    2009-01-01

    This thesis concerns technical aspects related to the design and operation of the submillimetre common-user bolometer array 2 (SCUBA-2) instrument, a new wide-field camera for submillimetre astronomy currently undergoing commissioning on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. Offering unprecedented sensitivity and mapping capabilities, SCUBA-2 is expected to make a major impact in surveys of the sky at submillimetre wavelengths, a largely unexplored part of the electromagnetic spectrum, and provide better understanding of the formation and evolution of galaxies, stars and planets by providing large, unbiased samples of such objects. SCUBA-2 uses large arrays of bolometers, with superconducting transition edge sensors (TESs) as the temperature-sensitive element. TES devices are a relatively new technology, utilising the sharp resistance change between the normal and superconducting states to make a sensitive thermistor. Kilopixel arrays of such devices are multiplexed using superconducting quantum interference devices (SQUIDs). This thesis derives the key detector performance parameters, and presents analysis of engineering data to confirm the detector performance on array scales. A key issue for bolometric instruments for far infrared and submillimetre astronomy is the need to operate at extremely low temperatures in the sub-kelvin and millikelvin ranges to achieve the necessary detector sensitivity. This work describes the design, testing and performance of the liquid cryogen-free millikelvin cryostat, the first such instrument to be deployed for astronomy. Subsequent chapters detail the design and testing of a magnetic shielding scheme for the instrument, an important aspect of the operation of superconducting devices. Based on experience with the construction and testing of this instrument, a number of potential improvements for future instruments are presented and discussed.

  18. Does recreational scuba diving have clinically significant effect on routine haematological parameters?

    Science.gov (United States)

    Perovic, Antonija; Nikolac, Nora; Braticevic, Marina Njire; Milcic, Ana; Sobocanec, Sandra; Balog, Tihomir; Dabelic, Sanja; Dumic, Jerka

    2017-06-15

    Scuba diving represents a combination of exercise and changes in environmental conditions. This study aimed to evaluate changes in haematological parameters after recreational scuba diving in order to identify clinically significant changes. The study included males, 17 recreational divers, median age (range) 41 (30-52) years. Blood samples were taken before diving, immediately after diving to 30 meters for 30 minutes, 3 hours and 6 hours after diving. Complete blood counts were analyzed on the Cell Dyn Ruby haematology analyzer. Statistical significance between successive measurements was tested using Friedman test. The difference between the two measurements was judged against desirable bias (DSB) derived from biological variation and calculated reference change values (RCV). The difference higher than RCV was considered clinically significant. A statistically significant increase and difference judging against DSB was observed: for neutrophils immediately, 3 and 6 hours after diving (18%, 34% and 36%, respectively), for white blood cells (WBCs) 3 and 6 hours after diving (20% and 25%, respectively), for lymphocytes (20%) and monocytes (23%) 6 hours after diving. A statistically significant decrease and difference judging against DSB was found: immediately after diving for monocytes (- 15%), 3 and 6 hours after diving for red blood cells (RBCs) (- 2.6% and -2.9%, respectively), haemoglobin (- 2.1% and - 2.8%, respectively) and haematocrit (- 2.4% and - 3.2%, respectively). A clinically significant change was not found for any of the test parameters when compared to RCV. Observed statistically significant changes after recreational scuba diving; WBCs, neutrophils, lymphocytes, monocytes increase and RBCs, haemoglobin, haematocrit decrease, probably will not affect clinical decision.

  19. Mobility, expansion and management of a multi-species scuba diving fishery in East Africa.

    Directory of Open Access Journals (Sweden)

    Hampus Eriksson

    Full Text Available BACKGROUND: Scuba diving fishing, predominantly targeting sea cucumbers, has been documented to occur in an uncontrolled manner in the Western Indian Ocean and in other tropical regions. Although this type of fishing generally indicates a destructive activity, little attention has been directed towards this category of fishery, a major knowledge gap and barrier to management. METHODOLOGY AND PRINCIPAL FINDINGS: With the aim to capture geographic scales, fishing processes and social aspects the scuba diving fishery that operate out of Zanzibar was studied using interviews, discussions, participant observations and catch monitoring. The diving fishery was resilient to resource declines and had expanded to new species, new depths and new fishing grounds, sometimes operating approximately 250 km away from Zanzibar at depths down to 50 meters, as a result of depleted easy-access stock. The diving operations were embedded in a regional and global trade network, and its actors operated in a roving manner on multiple spatial levels, taking advantage of unfair patron-client relationships and of the insufficient management in Zanzibar. CONCLUSIONS AND SIGNIFICANCE: This study illustrates that roving dynamics in fisheries, which have been predominantly addressed on a global scale, also take place at a considerably smaller spatial scale. Importantly, while proposed management of the sea cucumber fishery is often generic to a simplified fishery situation, this study illustrates a multifaceted fishery with diverse management requirements. The documented spatial scales and processes in the scuba diving fishery emphasize the need for increased regional governance partnerships to implement management that fit the spatial scales and processes of the operation.

  20. Pressure cylinders under fire condition

    Directory of Open Access Journals (Sweden)

    Jan Hora

    2016-03-01

    Full Text Available The presence of pressure cylinders under fire conditions significantly increases the risk rate for the intervening persons. It is considerably problematic to predict the pressure cylinders behaviour during heat exposition, its destruction progress and possible following explosion of the produced air–gas mixture because pressure cylinders and its environment generate a highly complicated dynamic system during an uncontrolled destruction. The large scale tests carried out by the Pilsen Fire and Rescue Department and the Rapid Response Unit of the Czech Republic Police in October 2012 and in May 2014 in the Military area Brdy and in the area of the former Lachema factory in Kaznějov had several objectives, namely, to record, qualify and quantify some of the aspects of an uncontrolled heat destruction procedure of an exposed pressure cylinder in an enclosed space and to qualify and describe the process of a controlled destruction of a pressure cylinder by shooting through it including basic tactical concepts. The article describes the experiments that were carried out.

  1. Magnetofluidic concentration and separation of non-magnetic particles using two magnet arrays.

    Science.gov (United States)

    Hejazian, Majid; Nguyen, Nam-Trung

    2016-07-01

    The present paper reports the use of diluted ferrofluid and two arrays of permanent magnets for the size-selective concentration of non-magnetic particles. The micro magnetofluidic device consists of a straight channels sandwiched between two arrays of permanent magnets. The permanent magnets create multiple capture zones with minimum magnetic field strength along the channel. The complex interaction between magnetic forces and hydrodynamic force allows the device to operate in different regimes suitable for concentration of non-magnetic particles with small difference in size. Our experimental results show that non-magnetic particles with diameters of 3.1 μm and 4.8 μm can be discriminated and separated with this method. The results from this study could be used as a guide for the design of size-sensitive separation devices for particle and cell based on negative magnetophoresis.

  2. Scuba diving, patent foramen ovale and heart rhythm disturbances: The role of underwater Holter monitoring-Case report.

    Science.gov (United States)

    Olędzki, Szymon; Wojtarowicz, Andrzej; Płońska-Gościniak, Edyta; Lewandowski, Maciej; Gorący, Jarosław

    2017-09-01

    Patent foramen ovale (PFO) is thought to be a risk factor for decompression illness (DCI). Catheter-based closure procedure reduces the risk of DCI in selected scuba divers with PFO. Major complication of invasive approach are rare, minor, especially heart rhythm disturbances are reported relatively often. We describe a case of 41-year-old diver, who underwent PFO closure due to recurrent DCI events. Afterward, he experienced no DCI symptoms; however, he complained about feeling of the heart beating during a submersion. Arrhythmia should be considered as a life-threatening for scuba diver, thus we performed underwater ECG monitoring and exclude the arrhythmia. © 2017 Wiley Periodicals, Inc.

  3. Blower Cooling of Finned Cylinders

    Science.gov (United States)

    Schey, Oscar W; Ellerbrock, Herman H , Jr

    1937-01-01

    Several electrically heated finned steel cylinders enclosed in jackets were cooled by air from a blower. The effect of the air conditions and fin dimensions on the average surface heat-transfer coefficient q and the power required to force the air around the cylinders were determined. Tests were conducted at air velocities between the fins from 10 to 130 miles per hour and at specific weights of the air varying from 0.046 to 0.074 pound per cubic foot. The fin dimensions of the cylinders covered a range in pitches from 0.057 to 0.25 inch average fin thicknesses from 0.035 to 0.04 inch, and fin widths from 0.67 to 1.22 inches.

  4. Filament winding cylinders. I - Process model

    Science.gov (United States)

    Lee, Soo-Yong; Springer, George S.

    1990-01-01

    A model was developed which describes the filament winding process of composite cylinders. The model relates the significant process variables such as winding speed, fiber tension, and applied temperature to the thermal, chemical and mechanical behavior of the composite cylinder and the mandrel. Based on the model, a user friendly code was written which can be used to calculate (1) the temperature in the cylinder and the mandrel, (2) the degree of cure and viscosity in the cylinder, (3) the fiber tensions and fiber positions, (4) the stresses and strains in the cylinder and in the mandrel, and (5) the void diameters in the cylinder.

  5. PERCOLATION OF RANDOM CYLINDER AGGREGATES

    Directory of Open Access Journals (Sweden)

    Dominique Jeulin

    2011-05-01

    Full Text Available The percolation threshold ρc of Boolean models of cylinders with their axis parallel to a given direction is studied by means of simulations. An efficient method of construction of percolating connected components was developed, and is applied to one or two scales Boolean model, in order to simulate the presence of aggregates. The invariance of the percolation threshold with respect to affine transformations in the common direction of the axis of cylinders is approximately satisfied on simulations. The prediction of the model (ρc close to 0.16 is consistent with experimental measurements on plasma spray coatings, which motivated this study.

  6. The JCMT Gould Belt Survey: First results from SCUBA-2 observations of the Cepheus Flare Region

    CERN Document Server

    Pattle, Kate; Kirk, Jason M; Di Francesco, James; Kirk, Helen; Mottram, Joseph C; Keown, Jared; Buckle, Jane; Beaulieu, Sylvie F; Berry, David S; Broekhoven-Fiene, Hannah; Currie, Malcolm J; Fich, Michel; Hatchell, Jenny; Jenness, Tim; Johnstone, Doug; Nutter, David; Pineda, Jaime E; Quinn, Ciera; Salji, Carl; Tisi, Sam; Walker-Smith, Samantha; Hogerheijde, Michiel R; Bastien, Pierre; Bresnahan, David; Butner, Harold; Chen, Mike; Chrysostomou, Antonio; Coudé, Simon; Davis, Chris J; Drabek-Maunder, Emily; Duarte-Cabral, Ana; Fiege, Jason; Friberg, Per; Friesen, Rachel; Fuller, Gary A; Graves, Sarah; Greaves, Jane; Gregson, Jonathan; Holland, Wayne; Joncas, Gilles; Knee, Lewis B G; Mairs, Steve; Marsh, Ken; Matthews, Brenda C; Moriarty-Schieven, Gerald; Mowat, Chris; Rawlings, Jonathan; Richer, John; Robertson, Damien; Rosolowsky, Erik; Rumble, Damian; Sadavoy, Sarah; Thomas, Holly; Tothill, Nick; Viti, Serena; White, Glenn J; Wouterloot, Jan; Yates, Jeremy; Zhu, Ming

    2016-01-01

    We present observations of the Cepheus Flare obtained as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Legacy Survey (GBLS) with the SCUBA-2 instrument. We produce a catalogue of sources found by SCUBA-2, and separate these into starless cores and protostars. We determine masses and densities for each of our sources, using source temperatures determined by the Herschel Gould Belt Survey. We compare the properties of starless cores in four different molecular clouds: L1147/58, L1172/74, L1251 and L1228. We find that the core mass functions for each region typically show shallower-than-Salpeter behaviour. We find that L1147/58 and L1228 have a high ratio of starless cores to Class II protostars, while L1251 and L1174 have a low ratio, consistent with the latter regions being more active sites of current star formation, while the former are forming stars less actively. We determine that, if modelled as thermally-supported Bonnor-Ebert spheres, most of our cores have stable configurations accessible...

  7. SCUBA-2: iterative map-making with the Sub-Millimetre User Reduction Facility

    CERN Document Server

    Chapin, Edward L; Gibb, Andrew G; Jenness, Tim; Scott, Douglas; Tilanus, Remo P J; Economou, Frossie; Holland, Wayne S

    2013-01-01

    The Submillimetre Common User Bolometer Array 2 (SCUBA-2) is an instrument operating on the 15-m James Clerk Maxwell Telescope, nominally consisting of 5120 bolometers in each of two simultaneous imaging bands centred over 450 and 850 um. The camera is operated by scanning across the sky and recording data at a rate of 200 Hz. As the largest of a new generation of multiplexed kilopixel bolometer cameras operating in the (sub)millimetre, SCUBA-2 data analysis represents a significant challenge. We describe the production of maps using the Sub-Millimetre User Reduction Facility (SMURF) in which we have adopted a fast, iterative approach to map-making that enables data reduction on single, modern, high-end desktop computers, with execution times that are typically shorter than the observing times. SMURF is used in an automated setting, both at the telescope for real-time feedback to observers, as well as for the production of science products for the JCMT Science Archive at the Canadian Astronomy Data Centre. Th...

  8. Prevalence of dental problems in recreational SCUBA divers: a pilot survey.

    Science.gov (United States)

    Ranna, V; Malmstrom, H; Yunker, M; Feng, C; Gajendra, S

    2016-11-04

    Objective To determine the prevalence of dental symptoms in recreational scuba divers and describe the distribution of these symptoms on the basis of diver demographics, diving qualifications and dive conditions during the episode of dental pain.Design A survey was designed and distributed through online social media platforms dedicated to scuba diving. A convenience sample of 100 recreational divers was obtained by this method.Main outcome measures The outcome measures of interest were: diver demographics, diving characteristics (level of certification, number of dives completed), occurrence of dental problems during a dive, and details of the episode.Results Forty-one percent of the respondents experienced dental symptoms during a dive. Barodontalgia was the most frequently experienced dental symptom during a dive.Conclusion Within the limits of the small sample size and online method of recruitment, the findings of this study suggest that a high proportion of recreational divers may experience dental symptoms during a dive. It would be meaningful to ensure that dental decay and damaged restorations are addressed before a dive and that the mouthpiece design be evaluated in case of complaints of temporomandibular discomfort during a dive.

  9. Acute ischemic colitis during scuba diving:Report of a unique case

    Institute of Scientific and Technical Information of China (English)

    Konstantinos Goumas; Androniki Poulou; Ioannis Tyrmpas; Dimitrios Dandakis; Stavros Bartzokis; Magdalini Tsamouri; Kalipso Barbati; Dimitrios Soutos

    2008-01-01

    The presentation of clinical symptoms due to decompression during diving,varies significantly,as mainly minor disturbances for the gastrointestinal tract in particular have been reported.The following case debates whether diving can cause severe symptoms from the gastrointestinal system.We describe a clinical case of ischemic colitis presented in a 27-year-old male,who manifested abdominal pain while in the process of scuba diving 20 meters undersea,followed by bloody diarrhoea as soon as he ascended to sea level.Taking into account his past medical history,the thorough,impeccable clinical and laboratory examinations and presence of no other factors predisposing to ischemia of the colon,we assume that a possible relationship between diving conditions and the pathogenesis of ischemic colitis may exist.This unusual case might represent a hematologic manifestation of decompression sickness,due to increased coagulability and/or transient air emboli,occurring during a routine scuba diving ascent to sea level.

  10. A SCUBA-2 850 micron Survey of Protoplanetary Discs in the IC 348 Cluster

    CERN Document Server

    Cieza, L; Kourkchi, E; Andrews, S; Casassus, S; Graves, S; Schreiber, M

    2015-01-01

    We present 850 micron observations of the 2-3 Myr cluster IC 348 in the Perseus molecular cloud using the SCUBA-2 camera on the James Clerk Maxwell Telescope. Our SCUBA-2 map has a diameter of 30 arcmin and contains ~370 cluster members, including ~200 objects with IR excesses. We detect a total of 13 discs. Assuming standard dust properties and a gas to dust mass ratio of 100, we derive disc masses ranging from 1.5 to 16 M_JUP . We also detect 8 Class 0/I protostars. We find that the most massive discs (M_Disc > 3 MJUP ; 850 micron fux > 10 mJy) in IC 348 tend to be transition objects according to the characteristic "dip" in their infrared Spectral Energy Distributions (SEDs). This trend is also seen in other regions. We speculate that this could be an initial conditions effect (e.g., more massive discs tend to form giant planets that result in transition disc SEDs) and/or a disc evolution effect (the formation of one or more massive planets results in both a transition disc SED and a reduction of the accret...

  11. A new era of wide-field submillimetre imaging: on-sky performance of SCUBA-2

    CERN Document Server

    Dempsey, Jessica T; Chrysostomou, Antonio; Berry, David S; Bintley, Daniel; Chapin, Edward L; Craig, Simon C; Coulson, Iain M; Davis, Gary R; Friberg, Per; Jenness, Tim; Gibb, Andy G; Parsons, Harriet A L; Scott, Douglas; Thomas, Holly S; Tilanus, Remo P J; Robson, Ian; Walther, Craig A

    2012-01-01

    SCUBA-2 is the largest submillimetre wide-field bolometric camera ever built. This 43 square arc-minute field-of-view instrument operates at two wavelengths (850 and 450 microns) and has been installed on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. SCUBA-2 has been successfully commissioned and operational for general science since October 2011. This paper presents an overview of the on-sky performance of the instrument during and since commissioning in mid-2011. The on-sky noise characteristics and NEPs of the 450 and 850 micron arrays, with average yields of approximately 3400 bolometers at each wavelength, will be shown. The observing modes of the instrument and the on-sky calibration techniques are described. The culmination of these efforts has resulted in a scientifically powerful mapping camera with sensitivities that allow a square degree of sky to be mapped to 10 mJy/beam rms at 850 micron in 2 hours and 60 mJy/beam rms at 450 micron in 5 hours in the best weather.

  12. A Pilot Study for the SCUBA-2 'All-Sky' Survey

    CERN Document Server

    Mackenzie, Todd; Gibb, Andy G; Scott, Douglas; Jenness, Tim; Serjeant, Stephen; Thompson, Mark; Berry, David; Brunt, Christopher M; Chapin, Edward; Chrysostomou, Antonio; Clements, Dave; Coppin, Kristen; Economou, Frossie; Evans, A; Friberg, Per; Greaves, Jane; Hill, T; Holland, Wayne; Ivison, R J; Knapen, Johan H; Jackson, Neal; Joncas, Gilles; Morgan, Larry; Pearson, Chris; Pestalozzi, Michele; Pope, Alexandra; Richer, John; Urquhart, J S; Vaccari, Mattia; Weferling, Bernd; White, Glenn; Zhu, Ming

    2010-01-01

    We have carried out a pilot study for the SCUBA-2 'All-Sky' Survey, SASSy, a wide and shallow mapping project at 850 microns, designed to find rare objects, both Galactic and extragalactic. Two distinct sets of exploratory observations were undertaken, and used to test the SASSy approach and data reduction pipeline. The first was a 0.5 by 0.5 degrees map around the nearby galaxy NGC 2559. The galaxy was easily detected at 156 mJy, but no other convincing sources are present in the map. Comparison with other galaxies with similar wavelength coverage indicates that NGC 2559 has relatively warm dust. The second observations cover 1 square degree around the W5-E HII region. As well as diffuse structure in the map, a filtering approach was able to extract 27 compact sources with signal-to-noise greater than 6. By matching with data at other wavelengths we can see that the SCUBA-2 data can be used to discriminate the colder cores. Together these observations show that the SASSy project will be able to meet its orig...

  13. The SCUBA-2 Cosmology Legacy Survey: 850um maps, catalogues and number counts

    CERN Document Server

    Geach, J E; Halpern, M; Smail, Ian; van der Werf, P; Alexander, D M; Almaini, O; Aretxaga, I; Arumugam, V; Asboth, V; Banerji, M; Beanlands, J; Best, P N; Blain, A W; Birkinshaw, M; Chapin, E L; Chapman, S C; Chen, C-C; Chrysostomou, A; Clarke, C; Clements, D L; Conselice, C; Coppin, K E K; Cowley, W I; Danielson, A L R; Eales, S; Edge, A C; Farrah, D; Gibb, A; Harrison, C M; Hine, N K; Hughes, D; Ivison, R J; Jarvis, M; Jenness, T; Jones, S F; Karim, A; Koprowski, M; Knudsen, K K; Lacey, C G; Mackenzie, T; Marsden, G; McAlpine, K; McMahon, R; Meijerink, R; Michalowski, M J; Oliver, S J; Page, M J; Peacock, J A; Rigopoulou, D; Robson, E I; Roseboom, I; Rotermund, K; Scott, Douglas; Serjeant, S; Simpson, C; Simpson, J M; Smith, D J B; Spaans, M; Stanley, F; Stevens, J A; Swinbank, A M; Targett, T; Thomson, A P; Valiante, E; Webb, T M A; Willott, C; Zavala, J A; Zemcov, M

    2016-01-01

    We present a catalogue of nearly 3,000 submillimetre sources detected at 850um over ~5 square degrees surveyed as part of the James Clerk Maxwell Telescope (JCMT) SCUBA-2 Cosmology Legacy Survey (S2CLS). This is the largest survey of its kind at 850um, probing a meaningful cosmic volume at the peak of star formation activity and increasing the sample size of submillimetre galaxies selected at 850um by an order of magnitude. We describe the wide 850um survey component of S2CLS, which covers the key extragalactic survey fields: UKIDSS-UDS, COSMOS, Akari-NEP, Extended Groth Strip, Lockman Hole North, SSA22 and GOODS-North. The average 1-sigma depth of S2CLS is 1.2 mJy/beam, approaching the SCUBA-2 850um confusion limit, which we determine to be ~0.8 mJy/beam. We measure the single dish 850um number counts to unprecedented accuracy, reducing the Poisson errors on the differential counts to approximately 4% at S_850~3mJy. With several independent fields, we investigate field-to-field variance, finding that the num...

  14. Diving dentistry: a review of the dental implications of scuba diving.

    Science.gov (United States)

    Zadik, Y; Drucker, S

    2011-09-01

    In light of the overwhelming popularity of self-contained underwater breathing apparatus (SCUBA) diving, general dental practitioners should be prepared to address complications arising as a result of diving and to provide patients with accurate information. The aim of this article was to introduce the concepts of diving medicine and dentistry to the dentist, and to supply the dental practitioner with some diagnostic tools as well as treatment guidelines. The literature was reviewed to address diving barotrauma (pressure-induced injury related to an air space) to the head, face and oral regions, as well as scuba mouthpiece-related oral conditions. The relevant conditions for dentists who treat divers include diving-associated headache (migraine, tension-type headache), barosinusitis and barotitis-media (sinus and middle ear barotrauma, respectively), neuropathy, trigeminal (CN V) or facial (CN VII) nerve baroparesis (pressure-induced palsy), dental barotrauma (barometric-related tooth injury), barodontalgia (barometric-related dental pain), mouthpiece-associated herpes infection, pharyngeal gag reflex and temporomandibular joint disorder (dysfunction). For each condition, a theoretical description is followed by practical recommendations for the dental practitioner for the prevention and management of the condition.

  15. Non-magnetic negative-refraction systems for terahertz and far-infrared frequencies

    CERN Document Server

    Alekseyev, Leonid V; Narimanov, Evgenii E

    2012-01-01

    We demonstrate that homogeneous naturally-occurring materials can form non-magnetic negative refractive index systems, and present specific realizations of the proposed approach for the THz and far-IR frequencies. The proposed structure operates away from resonance, thereby promising the capacity for low-loss devices.

  16. Nurse Outcomes in Magnet® and Non-Magnet Hospitals

    Science.gov (United States)

    Kelly, Lesly A.; McHugh, Matthew D.; Aiken, Linda H.

    2017-01-01

    The important goals of Magnet® hospitals are to create supportive professional nursing care environments. A recently published paper found little difference in work environments between Magnet and non-Magnet hospitals. The aim of this study was to determine whether work environments, staffing, and nurse outcomes differ between Magnet and non-Magnet hospitals. A secondary analysis of data from a 4-state survey of 26,276 nurses in 567 acute care hospitals to evaluate differences in work environments and nurse outcomes in Magnet and non-Magnet hospitals was conducted. Magnet hospitals had significantly better work environments (t = −5.29, P < .001) and more highly educated nurses (t = −2.27, P < .001). Magnet hospital nurses were 18% less likely to be dissatisfied with their job (P < .05) and 13% less likely to report high burnout (P < .05). Magnet hospitals have significantly better work environments than non-Magnet hospitals. The better work environments of Magnet hospitals are associated with lower levels of nurse job dissatisfaction and burnout. PMID:22976894

  17. Pulsed remote field eddy current technique applied to non-magnetic flat conductive plates

    Science.gov (United States)

    Yang, Binfeng; Zhang, Hui; Zhang, Chao; Zhang, Zhanbin

    2013-12-01

    Non-magnetic metal plates are widely used in aviation and industrial applications. The detection of cracks in thick plate structures, such as multilayered structures of aircraft fuselage, has been challenging in nondestructive evaluation societies. The remote field eddy current (RFEC) technique has shown advantages of deep penetration and high sensitivity to deeply buried anomalies. However, the RFEC technique is mainly used to evaluate ferromagnetic tubes. There are many problems that should be fixed before the expansion and application of this technique for the inspection of non-magnetic conductive plates. In this article, the pulsed remote field eddy current (PRFEC) technique for the detection of defects in non-magnetic conducting plates was investigated. First, the principle of the PRFEC technique was analysed, followed by the analysis of the differences between the detection of defects in ferromagnetic and non-magnetic plain structures. Three different models of the PRFEC probe were simulated using ANSYS. The location of the transition zone, defect detection sensitivity and the ability to detect defects in thick plates using three probes were analysed and compared. The simulation results showed that the probe with a ferrite core had the highest detecting ability. The conclusions derived from the simulation study were also validated by conducting experiments.

  18. On certain geodesic conjugacies of flat cylinders

    Indian Academy of Sciences (India)

    C S ARAVINDA; H A GURURAJA

    2017-06-01

    We prove $C^0$-conjugacy rigidity of any flat cylinder among two different classes of metrics on the cylinder, namely among the class of rotationally symmetric metrics and among the class of metrics without conjugate points.

  19. Anisotropic Poisson Processes of Cylinders

    CERN Document Server

    Spiess, Malte

    2010-01-01

    Main characteristics of stationary anisotropic Poisson processes of cylinders (dilated k-dimensional flats) in d-dimensional Euclidean space are studied. Explicit formulae for the capacity functional, the covariance function, the contact distribution function, the volume fraction, and the intensity of the surface area measure are given which can be used directly in applications.

  20. The JCMT and Herschel Gould Belt Surveys: A comparison of SCUBA-2 and Herschel data of dense cores in the Taurus dark cloud L1495

    CERN Document Server

    Ward-Thompson, Derek; Kirk, Jason; Marsh, Ken; Buckle, Jane; Hatchell, Jennifer; Nutter, David; Griffin, Matt; Di Francesco, James; André, Philippe; Beaulieu, Sylvie; Berry, David; Broekhoven-Fiene, Hannah; Currie, Malcolm; Fich, Michel; Jenness, Timothy; Johnstone, Doug; Kirk, Helen; Mottram, Joseph; Pineda, Jaime; Quinn, Ciera; Sadavoy, Sarah; Salji, Carl; Tisi, Sam; Walker-Smith, Sarah; White, Glenn; Hill, Tracey; Könyves, Vera; Palmeirim, Pedro; Pezzuto, Stefano

    2016-01-01

    We present a comparison of SCUBA-2 850-$\\mu$m and Herschel 70--500-$\\mu$m observations of the L1495 filament in the Taurus Molecular Cloud with the goal of characterising the SCUBA-2 Gould Belt Survey (GBS) data set. We identify and characterise starless cores in three data sets: SCUBA-2 850-$\\mu$m, Herschel 250-$\\mu$m, and Herschel 250-$\\mu$m spatially filtered to mimic the SCUBA-2 data. SCUBA-2 detects only the highest-surface-brightness sources, principally detecting protostellar sources and starless cores embedded in filaments, while Herschel is sensitive to most of the cloud structure, including extended low-surface-brightness emission. Herschel detects considerably more sources than SCUBA-2 even after spatial filtering. We investigate which properties of a starless core detected by Herschel determine its detectability by SCUBA-2, and find that they are the core's temperature and column density (for given dust properties). For similar-temperature cores, such as those seen in L1495, the surface brightness...

  1. Natural convective heat transfer from square cylinder

    Science.gov (United States)

    Novomestský, Marcel; Smatanová, Helena; Kapjor, Andrej

    2016-06-01

    This article is concerned with natural convective heat transfer from square cylinder mounted on a plane adiabatic base, the cylinders having an exposed cylinder surface according to different horizontal angle. The cylinder receives heat from a radiating heater which results in a buoyant flow. There are many industrial applications, including refrigeration, ventilation and the cooling of electrical components, for which the present study may be applicable

  2. Sensation Seeking: A Potential Factor Influencing Perceived Risk and Perceived Competence in an Introductory Scuba Diving Course

    Science.gov (United States)

    Morgan, Cass

    2009-01-01

    This study examined the relationship between the sensation-seeking personality trait to changes in perceived risk and perceived competence during an adventure experience. Participants (n = 57) were enrolled in a 14-week introductory scuba diving course offered at a university in eastern North Carolina in 2006. The data was analyzed using a…

  3. Comparison of aerodynamic noise from three nose-cylinder combinations

    Science.gov (United States)

    Guenther, R. A.; Reding, M. P.

    1970-01-01

    Results of experiments with three different cylinder and blunted nose combinations are discussed. Combinations include smooth cylinder with single 15 deg cone, smooth cylinder with double cone of 25 and 10 deg, and longitudinally corrugated cylinder with similar double cone.

  4. Wake-induced vibrations in Tandem Cylinders

    Science.gov (United States)

    Mysa, Ravi Chaithanya; Jaiman, Rajeev Kumar

    2015-11-01

    The upstream cylinder is fixed in the tandem cylinders arrangement. The downstream cylinder is placed at a distance of four diameters from the upstream cylinder in the free stream direction and is mounted on a spring. The dynamic response of the downstream cylinder is studied at Reynolds number of 10,000. The transverse displacement amplitude of the downstream cylinder is larger compared to that of single cylinder in the post-lock-in region. The transverse dynamic response of the downstream cylinder in the post-lock-in region is characterized by a dominant low frequency component compared to shed frequency, which is nearer to the structural natural frequency. The interaction of upstream wake with the downstream cylinder is carefully analyzed to understand the introduction of low frequency component in the transverse load along with the shed frequency. We found that the stagnation point moves in proportional to the velocity of the cylinder and is in-phase with the velocity. The low frequency component in the stagnation point movement on the downstream cylinder is sustained by the interaction of upstream wake. The frequencies in the movement of the stagnation point is reflected in the transverse load resulting in large deformation of the cylinder. The authors wish to acknowledge support from A*STAR- SERC and Singapore Maritime Institute.

  5. EOWD-Eco Open Water Diver- New Divers License needed? Effect of Intensive SCUBA Diving on Fringing Reefs of the Northern Red Sea

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald

    2006-01-01

    Intensive recreational SCUBA diving threatens coral reef diversity and health [1]. Two anthropogenic factors contributing to coral reef decline are sedimentation [4] and damage from snorklers and SCUBA divers [1]. Physical contact of divers (fins, hands, equipment) and increased sedimentation...... are two major effects diredtly caused by SCUBA diving. Diver damage varies depending on the growth form of corals present. Branching corals appear to sustain most of the breaks although they are most affected [5]. As coral reef tourism continues to grow, the need to quantify, manage and mitigate...

  6. Design and Validation of a Breathing Detection System for Scuba Divers

    Directory of Open Access Journals (Sweden)

    Corentin Altepe

    2017-06-01

    Full Text Available Drowning is the major cause of death in self-contained underwater breathing apparatus (SCUBA diving. This study proposes an embedded system with a live and light-weight algorithm which detects the breathing of divers through the analysis of the intermediate pressure (IP signal of the SCUBA regulator. A system composed mainly of two pressure sensors and a low-power microcontroller was designed and programmed to record the pressure sensors signals and provide alarms in absence of breathing. An algorithm was developed to analyze the signals and identify inhalation events of the diver. A waterproof case was built to accommodate the system and was tested up to a depth of 25 m in a pressure chamber. To validate the system in the real environment, a series of dives with two different types of workload requiring different ranges of breathing frequencies were planned. Eight professional SCUBA divers volunteered to dive with the system to collect their IP data in order to participate to validation trials. The subjects underwent two dives, each of 52 min on average and a maximum depth of 7 m. The algorithm was optimized for the collected dataset and proved a sensitivity of inhalation detection of 97.5% and a total number of 275 false positives (FP over a total recording time of 13.9 h. The detection algorithm presents a maximum delay of 5.2 s and requires only 800 bytes of random-access memory (RAM. The results were compared against the analysis of video records of the dives by two blinded observers and proved a sensitivity of 97.6% on the data set. The design includes a buzzer to provide audible alarms to accompanying dive buddies which will be triggered in case of degraded health conditions such as near drowning (absence of breathing, hyperventilation (breathing frequency too high and skip-breathing (breathing frequency too low measured by the improper breathing frequency. The system also measures the IP at rest before the dive and indicates with

  7. Generalized Bistability in Origami Cylinders

    Science.gov (United States)

    Reid, Austin; Adda-Bedia, Mokhtar; Lechenault, Frederic

    Origami folded cylinders (origami bellows) have found increasingly sophisticated applications in space flight, medicine, and even experimental nuclear physics. In spite of this interest, a general understanding of the dynamics of an origami folded cylinder has been elusive. By solving the fully constrained behavior of a periodic fundamental origami cell defined by unit vectors, we have found an analytic solution for all possible rigid-face states accessible from a cylindrical Miura-ori pattern. Although an idealized bellows has two rigid-face configurations over a well-defined region, a physical device, limited by nonzero material thickness and forced to balance hinge with plate-bending energy, often cannot stably maintain a stowed configuration. We have identified and measured the parameters which control this emergent bistability, and have demonstrated the ability to fabricate bellows with tunable deployability.

  8. Cylinder components properties, applications, materials

    CERN Document Server

    2016-01-01

    Owing to the ever-increasing requirements to be met by gasoline and diesel engines in terms of CO2 reduction, emission behavior, weight, and service life, a comprehensive understanding of combustion engine components is essential today. It is no longer possible for professionals in automotive engineering to manage without the corresponding expertise, whether they work in the field of design, development, testing, or maintenance. This technical book provides in-depth answers to questions about design, production, and machining of cylinder components. In this second edition, every section has been revised and expanded to include the latest developments in the combustion engine. Content Piston rings Piston pins and piston pin circlips Bearings Connecting rods Crankcase and cylinder liners Target audience Engineers in the field of engine development and maintenanceLecturers and students in the areas of mechanical engineering, engine technology, and vehicle constructionAnyone interested in technology Publisher MAH...

  9. The JCMT Gould Belt Survey: A First Look at Southern Orion A with SCUBA-2

    CERN Document Server

    Mairs, Steve; Kirk, H; Buckle, J; Berry, D S; Broekhoven-Fiene, H; Currie, M J; Fich, M; Graves, S; Hatchell, J; Jenness, T; Mottram, J C; Nutter, D; Pattle, K; Pineda, J E; Salji, C; Di Francesco, J; Hogerheijde, M R; Ward-Thompson, D; Bastien, P; Bresnahan, D; Butner, H; Chen, M; Chrysostomou, A; Coudé, S; Davis, C J; Drabek-Maunder, E; Duarte-Cabral, A; Fiege, J; Friberg, P; Friesen, R; Fuller, G A; Greaves, J; Gregson, J; Holland, W; Joncas, G; Kirk, J M; Knee, L B G; Marsh, K; Matthews, B C; Moriarty-Schieven, G; Mowat, C; Rawlings, J; Richer, J; Robertson, D; Rosolowsky, E; Rumble, D; Sadavoy, S; Thomas, H; Tothill, N; Viti, S; White, G J; Wouterloot, J; Yates, J; Zhu, M

    2016-01-01

    We present the JCMT Gould Belt Survey's first look results of the southern extent of the Orion A Molecular Cloud ($\\delta \\leq -5\\mathrm{:}31\\mathrm{:}27.5$). Employing a two-step structure identification process, we construct individual catalogues for large-scale regions of significant emission labelled as islands and smaller-scale subregions called fragments using the 850 $\\mu$m continuum maps obtained using SCUBA-2. We calculate object masses, sizes, column densities, and concentrations. We discuss fragmentation in terms of a Jeans instability analysis and highlight interesting structures as candidates for follow-up studies. Furthermore, we associate the detected emission with young stellar objects (YSOs) identified by Spitzer and Herschel. We find that although the population of active star-forming regions contains a wide variety of sizes and morphologies, there is a strong positive correlation between the concentration of an emission region and its calculated Jeans instability. There are, however, a numb...

  10. A Review of SCUBA Diving Impacts and Implication for Coral Reefs Conservation and Tourism Management

    Directory of Open Access Journals (Sweden)

    Zainal Abidin Siti Zulaiha

    2014-01-01

    Full Text Available Dive tourism has become important in term of magnitude and significantly contributes to regional economies. Nevertheless, in the absence of proper controls and enforcement, unplanned tourism growth has caused environmental degradation which undermines the long-term sustainability of the tourism industry. The purpose of this paper is to explore factors that contribute to the SCUBA diving impacts on coral and fish communities. This paper explains the causes of a certain event, validating the problem of impacts, defining the core issues and identifies possible causes leading to an effect. The phenomenon of diving impacts on coral reefs is a result of intensive use of dive site over the long-term. The divers can reduce their impacts towards coral reefs through responsible diving behaviors. The causes of cumulative diver’s contacts are more complicated than it seems. In response, this paper proposes the best mitigation strategies that need to be considered for future dive tourism management.

  11. Bonding durability of custom-made mouthpiece for scuba diving after water storage under pressure.

    Science.gov (United States)

    Ihara, Chie; Takahashi, Hidekazu; Matsui, Ryosuke; Yamanaka, Takuto; Ueno, Toshiaki

    2009-07-01

    The purpose of this study was to assess the behavior of laminated thermoforming materials in an underwater environment to understand the durability of mouthpieces for scuba diving. Two thermoforming materials, polyolefin (PO) and ethylene-vinyl acetate copolymer (EV), were laminated and stored in air, 37 degrees C water, and 37 degrees C water under 0.2-MPa pressure for 1 and 4 weeks . The load/ bonding width (bonding strength: BS) and displacement at the start of delamination (SD) and fracture (FR) were analyzed with 3-way ANOVA. BS values at SD and FR in air were significantly greater than those under the other conditions, and the BS at SD of EV was significantly greater than that of PO, though the effects of materials, duration and their interactions were not significantly different. The displacements at SD and FR were significantly influenced by the material. These results suggest that both materials can be employed for making a diving custom mouthpiece.

  12. Counting Polyominoes on Twisted Cylinders

    OpenAIRE

    Barequet, Gill; Moffie, Micha; Ribó, Ares; Rote, Günter

    2005-01-01

    International audience; We improve the lower bounds on Klarner's constant, which describes the exponential growth rate of the number of polyominoes (connected subsets of grid squares) with a given number of squares. We achieve this by analyzing polyominoes on a different surface, a so-called $\\textit{twisted cylinder}$ by the transfer matrix method. A bijective representation of the "states'' of partial solutions is crucial for allowing a compact representation of the successive iteration vec...

  13. Imaging the environment of a z = 6.3 submillimeter galaxy with SCUBA-2

    Energy Technology Data Exchange (ETDEWEB)

    Robson, E. I.; Holland, W. S. [United Kingdom Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Ivison, R. J. [European Space Observatory, Karl Schwarzschild Strasse 2, D-85748 Garching (Germany); Smail, Ian [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Geach, J. E. [Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Gibb, A. G. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Riechers, D. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Ade, P. A. R. [Astronomy and Instrumentation Group, Cardiff University, Cardiff, Wales CF10 3XQ (United Kingdom); Bintley, D. [Joint Astronomy Centre, 660 North Ahoku Place, University Park, Hilo, HI 96720 (United States); Bock, J. [Jet Propulsion Laboratory, National Aeronautics and Space Administration, Pasadena, CA 91109 (United States); Chapin, E. L. [XMM-Newton Science Operations Centre, European Space Astronomy Centre, Apartado 79, E-28691 Villaneueva de la Canada, Madrid (Spain); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, Coburg Road, Halifax B3H 1A6 (Canada); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Conley, A. [Center for Astrophysics and Space Astronomy, 389 UCB, University of Colorado, Boulder, CO 80309 (United States); Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Dunlop, J. S. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Farrah, D., E-mail: rob.ivison@gmail.com [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); and others

    2014-09-20

    We describe a search for submillimeter emission in the vicinity of one of the most distant, luminous galaxies known, HerMES FLS3, at z = 6.34, exploiting it as a signpost to a potentially biased region of the early universe, as might be expected in hierarchical structure formation models. Imaging to the confusion limit with the innovative, wide-field submillimeter bolometer camera, SCUBA-2, we are sensitive to colder and/or less luminous galaxies in the surroundings of HFLS3. We use the Millennium Simulation to illustrate that HFLS3 may be expected to have companions if it is as massive as claimed, but find no significant evidence from the surface density of SCUBA-2 galaxies in its vicinity, or their colors, that HFLS3 marks an overdensity of dusty, star-forming galaxies. We cannot rule out the presence of dusty neighbors with confidence, but deeper 450 μm imaging has the potential to more tightly constrain the redshifts of nearby galaxies, at least one of which likely lies at z ≳ 5. If associations with HFLS3 can be ruled out, this could be taken as evidence that HFLS3 is less biased than a simple extrapolation of the Millennium Simulation may imply. This could suggest either that it represents a rare short-lived, but highly luminous, phase in the evolution of an otherwise typical galaxy, or that this system has suffered amplification due to a foreground gravitational lens and so is not as intrinsically luminous as claimed.

  14. The circumstellar environment of IRAS 16293-2422. ISO-LWS and SCUBA observations

    Science.gov (United States)

    Correia, J. C.; Griffin, M.; Saraceno, P.

    2004-05-01

    We present far-infrared (FIR) continuum observations of the deeply embedded source IRAS 16293-2422 performed with the Long Wavelength Spectrometer (LWS) on-board the Infrared Space Observatory (ISO). We also report 450 and 850 μm mapping observations done with the Submillimetre Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope (JCMT). We combined these observations with IRAS and other JCMT data available in the literature to construct a complete spectral energy distribution (SED) of the source. A spherically symmetric dusty envelope model was used to reproduce the SED and to characterize the circumstellar matter around the object. We call attention to the fact that when using models such as the one presented here, one needs spatial information about the object to distinguish between different possible fits to the SED. A comparison between the intensity profiles at 450 and 850 μm obtained from the SCUBA observations and the profiles predicted by the model allowed us to constrain the size of the envelope and its density distribution. The SED and the 850 μm intensity profile of the source are consistent with a centrally peaked power law dust density distribution of the form ρ(r) ∝ r-p with p = 1.5-2, with a radius Renv = 3000-3250 AU, defining a very compact circumstellar envelope. We estimate a bolometric luminosity Lbol = 36 L⊙, an envelope mass Menv = 3.4 M⊙, and a submillimetre to bolometric luminosity ratio Lsubmm/Lbol = 1.9%, confirming that the source shows a submillimetre excess characteristic of Class 0 sources.

  15. The JCMT Gould Belt Survey: first results from SCUBA-2 observations of the Cepheus Flare region

    Science.gov (United States)

    Pattle, K.; Ward-Thompson, D.; Kirk, J. M.; Di Francesco, J.; Kirk, H.; Mottram, J. C.; Keown, J.; Buckle, J.; Beaulieu, S. F.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Hatchell, J.; Jenness, T.; Johnstone, D.; Nutter, D.; Pineda, J. E.; Quinn, C.; Salji, C.; Tisi, S.; Walker-Smith, S.; Hogerheijde, M. R.; Bastien, P.; Bresnahan, D.; Butner, H.; Chen, M.; Chrysostomou, A.; Coudé, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Mowat, C.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Rumble, D.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wouterloot, J.; Yates, J.; Zhu, M.

    2017-02-01

    We present observations of the Cepheus Flare obtained as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Legacy Survey (GBLS) with the SCUBA-2 instrument. We produce a catalogue of sources found by SCUBA-2, and separate these into starless cores and protostars. We determine masses and densities for each of our sources, using source temperatures determined by the Herschel Gould Belt Survey. We compare the properties of starless cores in four different molecular clouds: L1147/58, L1172/74, L1251 and L1228. We find that the core mass functions for each region typically show shallower-than-Salpeter behaviour. We find that L1147/58 and L1228 have a high ratio of starless cores to Class II protostars, while L1251 and L1174 have a low ratio, consistent with the latter regions being more active sites of current star formation, while the former are forming stars less actively. We determine that if modelled as thermally supported Bonnor-Ebert spheres, most of our cores have stable configurations accessible to them. We estimate the external pressures on our cores using archival 13CO velocity dispersion measurements and find that our cores are typically pressure confined, rather than gravitationally bound. We perform a virial analysis on our cores, and find that they typically cannot be supported against collapse by internal thermal energy alone, due primarily to the measured external pressures. This suggests that the dominant mode of internal support in starless cores in the Cepheus Flare is either non-thermal motions or internal magnetic fields.

  16. Microparticle production, neutrophil activation, and intravascular bubbles following open-water SCUBA diving.

    Science.gov (United States)

    Thom, Stephen R; Milovanova, Tatyana N; Bogush, Marina; Bhopale, Veena M; Yang, Ming; Bushmann, Kim; Pollock, Neal W; Ljubkovic, Marko; Denoble, Petar; Dujic, Zeljko

    2012-04-01

    The goal of this study was to evaluate annexin V-positive microparticles (MPs) and neutrophil activation in humans following decompression from open-water SCUBA diving with the hypothesis that changes are related to intravascular bubble formation. Sixteen male volunteer divers followed a uniform profile of four daily SCUBA dives to 18 m of sea water for 47 min. Blood was obtained prior to and at 80 min following the first and fourth dives to evaluate the impact of repetitive diving, and intravascular bubbles were quantified by trans-thoracic echocardiography carried out at 20-min intervals for 2 h after each dive. MPs increased by 3.4-fold after each dive, neutrophil activation occurred as assessed by surface expression of myeloperoxidase and the CD18 component of β(2)-integrins, and there was an increased presence of the platelet-derived CD41 protein on the neutrophil surface indicating interactions with platelet membranes. Intravascular bubbles were detected in all divers. Surprisingly, significant inverse correlations were found among postdiving bubble scores and MPs, most consistently at 80 min or more after the dive on the fourth day. There were significant positive correlations between MPs and platelet-neutrophil interactions after the first dive and between platelet-neutrophil interactions and neutrophil activation documented as an elevation in β(2)-integrin expression after the fourth dive. We conclude that MPs- and neutrophil-related events in humans are consistent with findings in an animal decompression model. Whether there are causal relationships among bubbles, MPs, platelet-neutrophil interactions, and neutrophil activation remains obscure and requires additional study.

  17. The SCUBA-2 Cosmology Legacy Survey: 850 μm maps, catalogues and number counts

    Science.gov (United States)

    Geach, J. E.; Dunlop, J. S.; Halpern, M.; Smail, Ian; van der Werf, P.; Alexander, D. M.; Almaini, O.; Aretxaga, I.; Arumugam, V.; Asboth, V.; Banerji, M.; Beanlands, J.; Best, P. N.; Blain, A. W.; Birkinshaw, M.; Chapin, E. L.; Chapman, S. C.; Chen, C.-C.; Chrysostomou, A.; Clarke, C.; Clements, D. L.; Conselice, C.; Coppin, K. E. K.; Cowley, W. I.; Danielson, A. L. R.; Eales, S.; Edge, A. C.; Farrah, D.; Gibb, A.; Harrison, C. M.; Hine, N. K.; Hughes, D.; Ivison, R. J.; Jarvis, M.; Jenness, T.; Jones, S. F.; Karim, A.; Koprowski, M.; Knudsen, K. K.; Lacey, C. G.; Mackenzie, T.; Marsden, G.; McAlpine, K.; McMahon, R.; Meijerink, R.; Michałowski, M. J.; Oliver, S. J.; Page, M. J.; Peacock, J. A.; Rigopoulou, D.; Robson, E. I.; Roseboom, I.; Rotermund, K.; Scott, Douglas; Serjeant, S.; Simpson, C.; Simpson, J. M.; Smith, D. J. B.; Spaans, M.; Stanley, F.; Stevens, J. A.; Swinbank, A. M.; Targett, T.; Thomson, A. P.; Valiante, E.; Wake, D. A.; Webb, T. M. A.; Willott, C.; Zavala, J. A.; Zemcov, M.

    2017-02-01

    We present a catalogue of ˜3000 submillimetre sources detected (≥3.5σ) at 850 μm over ˜5 deg2 surveyed as part of the James Clerk Maxwell Telescope (JCMT) SCUBA-2 Cosmology Legacy Survey (S2CLS). This is the largest survey of its kind at 850 μm, increasing the sample size of 850 μm selected submillimetre galaxies by an order of magnitude. The wide 850 μm survey component of S2CLS covers the extragalactic fields: UKIDSS-UDS, COSMOS, Akari-NEP, Extended Groth Strip, Lockman Hole North, SSA22 and GOODS-North. The average 1σ depth of S2CLS is 1.2 mJy beam-1, approaching the SCUBA-2 850 μm confusion limit, which we determine to be σc ≈ 0.8 mJy beam-1. We measure the 850 μm number counts, reducing the Poisson errors on the differential counts to approximately 4 per cent at S850 ≈ 3 mJy. With several independent fields, we investigate field-to-field variance, finding that the number counts on 0.5°-1° scales are generally within 50 per cent of the S2CLS mean for S850 > 3 mJy, with scatter consistent with the Poisson and estimated cosmic variance uncertainties, although there is a marginal (2σ) density enhancement in GOODS-North. The observed counts are in reasonable agreement with recent phenomenological and semi-analytic models, although determining the shape of the faint-end slope (S850 10 mJy there are approximately 10 sources per square degree, and we detect the distinctive up-turn in the number counts indicative of the detection of local sources of 850 μm emission, and strongly lensed high-redshift galaxies. All calibrated maps and the catalogue are made publicly available.

  18. Recreational SCUBA divers' willingness to pay for marine biodiversity in Barbados.

    Science.gov (United States)

    Schuhmann, Peter W; Casey, James F; Horrocks, Julia A; Oxenford, Hazel A

    2013-05-30

    The use of natural resources and the services they provide often do not have an explicit price and are therefore undervalued in decision-making, leading to environmental degradation. To 'monetize' the benefits from these services requires the use of non-market valuation techniques. Using a stated preference survey of recreational divers in Barbados conducted between 2007 and 2009, the economic value of marine biodiversity to recreational SCUBA divers in Barbados was estimated. In addition to a variety of demographic variables, divers were asked about their level of experience, expenditures related to travel and diving, and encounters with fish and sea turtles. Divers then completed a choice experiment, selecting between alternative dives with varying characteristics including price, crowding, fish diversity, encounters with sea turtles, and coral cover. Results indicate that divers in Barbados have a clear appreciation of reef quality variables. Willingness to pay for good coral cover, fish diversity and presence of sea turtles is significantly higher than prices paid for dives. In general, divers valued reef attributes similarly, although their appreciation of low density of divers at a site and high coral cover varied with prior diving experience. The results of this study demonstrate the economic value generated in Barbados by the recreational SCUBA diving industry and highlight the potential for substantial additional economic contributions with improvements to the quality of a variety of reef attributes. These results could inform management decisions regarding reef use and sea turtle conservation, and could aid in the development of informed 'win-win' policies aimed at maximizing returns from diving while reducing negative impacts often associated with tourism activities. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Design and Analysis of Cylinder and Cylinder head of 4-stroke SI Engine for weight reduction

    Directory of Open Access Journals (Sweden)

    Ravindra R. Navthar

    2012-03-01

    Full Text Available The present paper deals with design of cylinder & cylinder head with air cooling system for 4 strokes 4 cylinder SI engine. The main objective of design is to reduce weight to power ratio & will result in producing high specific power. The authors have proposed preliminary design cylinder & cylinder head of a horizontallyopposed SI engine, which develops 120 BHP and posses the maximum rotational speed of 6000rpm. Four stroke opposed engine is inherently well balanced due to opposite location of moving masses and also it provides efficient air cooling. For the requirement of weight reduction the material selected for design of cylinder and cylinder head is Aluminum alloy that is LM-13. The cylinder bore coating using NIKASIL coating was done to improve strength of cylinder with minimum weight..

  20. Lingcod (Ophiodon elongatus) egg mass and reef fish density SCUBA survey in the Strait of Georgia, February 15-22, 2012

    National Research Council Canada - National Science Library

    by R.P. McPhie and J.R. King

    2012-01-01

    ...) egg mass density estimates. Previous lingcod egg mass SCUBA surveys involving egg mass counts were conducted at this index site in 1990, 1991, 1994, 2001, 2002, 2004, 2005, 2007, 2010, and 2011...

  1. SCAV2OBS -- Assorted visual observations of benthic habitat from ROV and SCUBA dives in the Channel Islands National Marine Sanctuary. (UTM 10N, NAD83)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Point based visual observations of benthic habitat from a variety of SCUBA and ROV dives. Unknown postitional accuracy. Some video data maintained by Russ Vetter,...

  2. Temperature profile along an induction heated, moving non-magnetic charge

    Energy Technology Data Exchange (ETDEWEB)

    Januszkiewicz, K.

    1984-01-01

    Induction heating system, comprising three sections of a heating coil connected in series and supplied from one source, will be discussed. The charge to be heated is a non-magnetic pipe moving with steady speed. The heating coil is water cooled. Digital methods are used to compute temperature variations along the charge from start up to steady state temperature and also to determine power development in the heating circuit. Cooling zones between the heating coil sections are taken into account.

  3. The Effectof Insert of WC Powder on the Surface Hardening of Non Magnetic Foundry Materials

    OpenAIRE

    Ike, Hiroyuki; Shobuzawa, Yoshiyuki; Goto, Shoji; Aso, Setsuo; Konishi, Nobuo

    2002-01-01

    Non magnetic foundry materials such as the austenitic stainless cast steel had not been used for abrasion resistant materials, because their hardnesses were very low. Usually, ceramics, cermets and cemented carbides are used for the abrasion resistant materials even though they are expensive compared with foundry materials. In this study, WC powder were inserted by using the austenitic stainless cast steel (JIS SCS13A) and the austenitic cast iron (JIS FCA-NiCr202) for producing surface ha...

  4. The space density and X-ray luminosity function of non-magnetic cataclysmic variables

    CERN Document Server

    Pretorius, Magaretha L

    2011-01-01

    We combine two complete, X-ray flux-limited surveys, the ROSAT Bright Survey (RBS) and the ROSAT North Ecliptic Pole (NEP) survey, to measure the space density (\\rho) and X-ray luminosity function (\\Phi) of non-magnetic CVs. The combined survey has a flux limit of F_X \\ga 1.1 \\times 10^{-12} erg cm^{-2}s^{-1} over most of its solid angle of just over 2\\pi, but is as deep as \\simeq 10^{-14} erg cm^{-2}s^{-1} over a small area. The CV sample that we construct from these two surveys contains 20 non-magnetic systems. We carefully include all sources of statistical error in calculating \\rho and \\Phi by using Monte Carlo simulations; the most important uncertainty proves to be the often large errors in distances estimates. If we assume that the 20 CVs in the combined RBS and NEP survey sample are representative of the intrinsic population, the space density of non-magnetic CVs is 4^{+6}_{-2} \\times 10^{-6} pc^{-3}. We discuss the difficulty in measuring \\Phi in some detail---in order to account for biases in the me...

  5. The Synergy between Scuba Diving and Household Behaviour: Testing Plastic and Food Waste "The use of natural habitats for tourism education"

    OpenAIRE

    Soares Mota, Luís Cândido

    2014-01-01

    The activity of scuba diving is used for studying behaviours of U.S. visitors to a popular tourist destination in Mexico. The impact created by human activity can produce marine debris and therefore affect the marine environment. The subpopulation of 181 divers was tested for their current household practices regarding discarding plastic and food waste, providing quantitative statistics for divers’ referential behaviour. Prior to partaking in scuba diving, certified, trainee, and “one-day-exp...

  6. Fire testing of bare uranium hexafluoride cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Pryor, W.A. [PAI Corp., Oak Rige, TN (United States)

    1991-12-31

    In 1965, the Oak Ridge Gaseous Diffusion Plant (ORGDP), now the K-25 Site, conducted a series of tests in which bare cylinders of uranium hexafluoride (UF{sub 6}) were exposed to engulfing oil fires for the US Atomic Energy Commission (AEC), now the US Department of Energy (DOE). The tests are described and the results, conclusions, and observations are presented. Two each of the following types of cylinders were tested: 3.5-in.-diam {times} 7.5-in.-long cylinders of Monel (Harshaw), 5.0-in.-diam {times} 30-in.-long cylinders of Monel, and 8-in.-diam {times} 48-in.-long cylinders of nickel. The cylinders were filled approximately to the standard UF{sub 6} fill limits of 5, 55, and 250 lb, respectively, with a U-235 content of 0.22%. The 5-in.- and 8-in.-diam cylinders were tested individually with and without their metal valve covers. For the 3.5-in.-diam Harshaw cylinders and the 5.0-in.-diam cylinder without a valve cover the valves failed and UF{sub 6} was released. The remaining cylinders ruptured explosively in time intervals ranging from about 8.5 to 11 min.

  7. Fire testing of bare uranium hexafluoride cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Pryor, W.A. [PAI Corp., Oak Ridge, TN (United States)

    1991-12-31

    In 1965, the Oak Ridge Gaseous Diffusion Plant (ORGDP), now the K-25 Site, conducted a series of tests in which bare cylinders of uranium hexafluoride (UF{sub 6}) were exposed to engulfing oil fires for the US Atomic Energy Commission (AEC), now the US Department of Energy (DOE). The tests are described and the results, conclusions, and observations are presented. Two each of the following types of cylinders were tested: 3.5-in.-diam {times} 7.5-in.-long cylinders of Monel (Harshaw), 5.0-in.-diam {times} x 30-in.-long cylinders of Monel, and 8-in.-diam {times} 48-in.-long cylinders of nickel. The cylinders were filled approximately to the standard UF{sub 6} fill limits of 5, 55, and 250 lb, respectively, with a U-235 content of 0.22%. The 5-in.- and 8-in.-diam cylinders were tested individually with and without their metal valve covers. For the 3.5-in.-diam Harshaw cylinders and the 5.0-in.-diam cylinder without a valve cover, the valves failed and UF{sub 6} was released. The remaining 6 cylinders ruptured explosively in time intervals ranging from about 8.5 to 11 min.

  8. Detection of cylinder pressure in diesel engines using cylinder head vibration and time series methods

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper investigates the vibration characteristics of diesel engine cylinder heads by means of the time series method.With the concept of "Assumed System", the vibration transfer function of real cylinder head structures is established using the autoregressive-moving average models (ARMA models) of cylinder head surface vibration signals.Then this transfer function is successfully used to reconstruct the gas pressure trace inside the cylinder from measured cylinder head vibration signals.This offers an effective means for diesel engine cylinder pressure detection and condition monitoring.

  9. Fatigue Tests with Densit Cylinders - D4

    DEFF Research Database (Denmark)

    Ellegaard, Peter

    This report contains descriptions and results of a series of fatigue tests performed during the autumn of 2005 at the Stuctural Research Laboratory, Aalborg University. Cylinders with a diameter of 45 mm and a height of 90 mm were used as test specimens; the material was Densit Ducorit D4. Four...... cylinders were tested statically under compression and the rest of the cylinders (30) were tested under fatigue conditions with a load varying sinusoidally....

  10. Rarita-Schwinger Type operators on Cylinders

    OpenAIRE

    2011-01-01

    Here we define Rarita-Schwinger operators on cylinders and construct their fundamental solutions. Further the fundamental solutions to the cylindrical Rarita-Schwinger type operators are achieved by applying translation groups. In turn, a Borel-Pompeiu Formula, Cauchy Integral Formula and a Cauchy Transform are presented for the cylinders. Moreover we show a construction of a number of conformally inequivalent spinor bundles on these cylinders. Again we construct Rarita-Schwinger operators an...

  11. Two interacting cylinders in cross flow

    Science.gov (United States)

    Alam, Md. Mahbub; Meyer, J. P.

    2011-11-01

    Cylindrical structures in a group are frequently seen on land and in the ocean. Mutual flow interaction between the structures makes the wake very excited or tranquil depending on the spacing between the structures. The excited wake-enhancing forces in some cases cause a catastrophic failure of the structures. This paper presents results of an experimental investigation of Strouhal number (St), time-mean, and fluctuating forces on, and flow structures around, two identical circular cylinders at stagger angle α = 0 °-180 ° and gap-spacing ratio T/D=0.1-5, where T is the gap width between the cylinders, and D is the diameter of a cylinder. While forces were measured using a load cell, St was from spectral analysis of fluctuating pressures measured on the side surfaces of the cylinders. A flow visualization test was conducted to observe flow structures around the cylinders. Based on forces, St, and flow structures, 19 distinct flow categories in the ranges of α and T/D investigated are observed, including one quadristable flow, three kinds of tristable flows, and four kinds of bistable flows. The quadristable, tristable, and bistable flows ensue from instabilities of the gap flow, shear layers, vortices, separation bubbles, and wakes, engendering a strong jump or drop in forces and St of the cylinders. The two cylinders interact with each other in six different mechanisms, namely interaction between boundary layer and cylinder, shear layer or wake and cylinder, shear layer and shear layer, vortex and cylinder, vortex and shear layer, and vortex and vortex. While the interaction between vortex and cylinder results in a very high fluctuating drag, that between vortex and shear layer results in a high fluctuating lift. On the other hand, the interaction between shear layer or wake and cylinder weakens mean and fluctuating forces and flow unsteadiness. A mutual discussion of forces, St, and flow structures is presented in this paper.

  12. Cylinder valve packing nut studies

    Energy Technology Data Exchange (ETDEWEB)

    Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

  13. Quantum Mechanics on the cylinder

    CERN Document Server

    González, J A; Tosiek, J

    2003-01-01

    A new approach to deformation quantization on the cylinder considered as phase space is presented. The method is based on the standard Moyal formalism for R^2 adapted to (S^1 x R) by the Weil--Brezin--Zak transformation. The results are compared with other solutions of this problem presented by Kasperkovitz and Peev (Ann. Phys. vol. 230, 21 (1994)0 and by Plebanski and collaborators (Acta Phys. Pol. vol. B 31}, 561 (2000)). The equivalence of these three methods is proved.

  14. INTERACTION OF A FLOATING ELLIPTIC CYLINDER WITH A VIBRATING CIRCULAR CYLINDER

    Institute of Scientific and Technical Information of China (English)

    SUN Ren; CHWANG Allen T.

    2006-01-01

    The nonlinear hydrodynamic interaction between a floating elliptic cylinder and a vibrating circular cylinder immersed in an infinite fluid was investigated. By taking the added masses of the two-cylinder system into account, the dynamical equations of motion were formulated from the Lagrange equations of motion. The dynamical behaviors of these two cylinders were analyzed numerically for some typical situations, and the results show that the presence of a vibrating circular cylinder has a significant influence on the planar motion of a floating elliptic cylinder. The hydrodynamic interaction between them results in complicated nonlinear behaviors of the floating cylinder. It is found that oscillatory motion of the elliptic cylinder takes place in response to the vibrating mode of the circular one.

  15. Comparative analysis of free and scuba diving for benthopelagic and cryptic fish species associated with rocky reefs

    Directory of Open Access Journals (Sweden)

    Rodolfo Gutterres Giordano

    2014-05-01

    Full Text Available This work aimed to assess, through experimental comparisons between free and scuba diving performed in Arraial do Cabo city, RJ, Brazil, the abundances of Scartella cristata e Chaetodon striatus -two reef fish species of contrasting behaviors- in different depth layers of sheltered and exposed rocky reefs. C. striatus was homogeneously distributed through all the depth strata (0-10 m and scuba diving should be preferred over free diving to assess the abundance of this species at exposed rocky shores, undergoing continuous effects of waves and winds. Both free and scuba diving can be used indistinctly and with no data biases to appraise the abundances of C. striatus in non-turbulent reefs or in shallow zones (i.e., ≤ 5 m of exposed reefs, and, for S. cristata, in all depth layers (i.e., up to 10 m of both sheltered and exposed reefs. Although the abundances of S. cristata did not significantly differ between free and scuba diving, contrasting with most previous studies that stressed the risk of the first method to underestimate the abundance of small and cryptic species, it should be considered that the previous experience of the diver and the nature of our study (i.e., focused specifically on a cryptic species may have contributed to our findings. Further studies are, however, necessary to test our findings in different conditions (i.e., depths, hydrodynamic characteristics, and habitat complexity and for other tropical reef fish species, in order to increase the truthfulness of underwater visual census and reduce the risk of failure of fish conservation and management programs potentially based on biased data.

  16. Inner cylinder of the CMS vacuum tank.

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    The vacuum tank of the CMS magnet system consists of inner and outer stainless-steel cylinders and houses the superconducting coil. The inner cylinder contains all the barrel sub-detectors, which it supports via a system of horizontal rails. The cylinder is pictured here in the vertical position on a yellow platform mounted on the ferris-wheel support structure. This will allow it to be pivoted and inserted into the outer cylinder already attached to the innermost ring of the barrel yoke.

  17. Fire exposure of empty 30B cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Ziehlke, K.T. [MJB Technical Associates, Inc., Knoxville, TN (United States)

    1991-12-31

    Cylinders for UF{sub 6} handling, transport, and storage are designed and built as unfired pressure vessels under ASME Boiler and Pressure Vessel Code criteria and standards. They are normally filled and emptied while UF{sub 6} is in its liquid phase. Transport cylinders such as the Model 30B are designed for service at 200 psi and 250{degrees}F, to sustain the process conditions which prevail during filling or emptying operations. While in transport, however, at ambient temperature the UF{sub 6} is solid, and the cylinder interior is well below atmospheric pressure. When the cylinders contain isotopically enriched product (above 1.0 percent U-235), they are transported in protective overpacks which function to guard the cylinders and their contents against thermal or mechanical damage in the event of possible transport accidents. Two bare Model 30B cylinders were accidentally exposed to a storage warehouse fire in which a considerable amount of damage was sustained by stored materials and the building structure, as well as by the cylinder valves and valve protectors. The cylinders were about six years old, and had been cleaned, inspected, hydrotested, and re-certified for service, but were still empty at the time of the fire. The privately-owned cylinders were transferred to DOE for testing and evaluation of the fire damage.

  18. Overseas shipments of 48Y cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, R.T.; Furlan, A.S. [Cameco Corp., Port Hope, Ontario (Canada)

    1991-12-31

    This paper describes experiences with two incidents of overseas shipments of uranium hexafluoride (UF{sub 6}) cylinders. The first incident involved nine empty UF{sub 6} cylinders in enclosed sea containers. Three UF{sub 6} cylinders broke free from their tie-downs and damaged and contaminated several sea containers. This paper describes briefly how decontamination was carried out. The second incident involved a shipment of 14 full UF{sub 6} cylinders. Although the incident did not cause an accident, the potential hazard was significant. The investigation of the cause of the near accident is recounted. Recommendations to alleviate future similar incidents for both cases are presented.

  19. Optimization and improvement of Halbach cylinder design

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders;

    2008-01-01

    that this parameter was optimal for long Halbach cylinders with small rex. Using the previously mentioned additional blocks of magnets can improve the parameter by as much as 15% as well as improve the homogeneity of the field in the cylinder bore. ©2008 American Institute of Physics......In this paper we describe the results of a parameter survey of a 16 segmented Halbach cylinder in three dimensions in which the parameters internal radius, rin, external radius, rex, and length, L, have been varied. Optimal values of rex and L were found for a Halbach cylinder with the least...

  20. The SCUBA-2 Cosmology Legacy Survey: the nature of bright submm galaxies from 2 deg2 of 850-um imaging

    CERN Document Server

    Michałowski, Michał J; Koprowski, M P; Cirasuolo, M; Geach, J E; Bowler, R A A; Mortlock, A; Caputi, K I; Aretxaga, I; Arumugam, V; Chen, Chian-Chou; McLure, R J; Birkinshaw, M; Bourne, N; Farrah, D; Ibar, E; van der Werf, P; Zemcov, M

    2016-01-01

    We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses (Mstar)] of nearly 2000 bright (S850 > 4 mJy) submm galaxies in the ~2 deg2 COSMOS and UDS fields selected with SCUBA-2 on the JCMT, representing the largest homogeneous sample of 850-um-selected sources to date. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up. Considering > 4 mJy ALMA sources, our identification method has a completeness of ~86 per cent with a reliability of ~92 per cent, and only ~15-20 per cent of sources are significantly affected by multiplicity (when a secondary component is brighter than a third of the primary one). The impact of source blending on the 850-um source counts as determined with SCUBA-2 is modest; scaling the single-dish fluxes by ~0.9 reproduces the ALMA source counts. We find median values of z = 2.40+0.10-0.04, SFR = 287+-6 Mo yr-1, and log(Mstar/Mo) = 11.12+-0.02. These properties clearly locate ...

  1. Flow control behind a circular cylinder via a porous cylinder in deep water

    Directory of Open Access Journals (Sweden)

    Akilli H.

    2013-04-01

    Full Text Available In this present work, the effects of surrounding outer porous cylinder on vortex structure downstream of a circular inner cylinder are investigated experimentally in deep water flow. The porosity of outer cylinder were selected as β = 0.4, 0.5, 0.6, 0.65, 0.7, 0.75, 0.8 and 0.85. Porosity is defined as the ratio of the gap area on the body to the whole body surface area. The ratio of outer cylinder diameter to inner cylinder diameter, Do/Di was selected as 2.0, i.e. the inner cylinder diameter is Di = 30 mm where the outer cylinder diameter is Do = 60 mm. All experiments were carried out above a platform. The water height between the base of the platform and the free surface was adjusted as 340 mm. Free stream velocity is U = 156 mm/s, which corresponds to the Reynolds number of Rei = 5,000 based on the inner cylinder diameter. It has been observed that the outer porous cylinders have influence on the attenuation of vortex shedding in the wake region for all porosities. The turbulent intensity of the flow is reduced at least 45% by the presence of outer porous cylinder compared to the bare cylinder case. The porosities β = 0.4 and 0.5 are most suitable cases to control the flow downstream of the circular cylinder.

  2. Hard sphere packings within cylinders.

    Science.gov (United States)

    Fu, Lin; Steinhardt, William; Zhao, Hao; Socolar, Joshua E S; Charbonneau, Patrick

    2016-03-07

    Arrangements of identical hard spheres confined to a cylinder with hard walls have been used to model experimental systems, such as fullerenes in nanotubes and colloidal wire assembly. Finding the densest configurations, called close packings, of hard spheres of diameter σ in a cylinder of diameter D is a purely geometric problem that grows increasingly complex as D/σ increases, and little is thus known about the regime for D > 2.873σ. In this work, we extend the identification of close packings up to D = 4.00σ by adapting Torquato-Jiao's adaptive-shrinking-cell formulation and sequential-linear-programming (SLP) technique. We identify 17 new structures, almost all of them chiral. Beyond D ≈ 2.85σ, most of the structures consist of an outer shell and an inner core that compete for being close packed. In some cases, the shell adopts its own maximum density configuration, and the stacking of core spheres within it is quasiperiodic. In other cases, an interplay between the two components is observed, which may result in simple periodic structures. In yet other cases, the very distinction between the core and shell vanishes, resulting in more exotic packing geometries, including some that are three-dimensional extensions of structures obtained from packing hard disks in a circle.

  3. Development of a Non-Magnetic Inertial Sensor for Vibration Stabilization in a Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Frisch, Josef; Decker, Valentin; Doyle, Eric; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas; Seryi, Andrei; /SLAC; Chang, Allison; Partridge, Richard; /Brown U.

    2006-09-01

    One of the options for controlling vibration of the final focus magnets in a linear collider is to use active feedback based on accelerometers. While commercial geophysics sensors have noise performance that substantially exceeds the requirements for a linear collider, they are physically large, and cannot operate in the strong magnetic field of the detector. Conventional nonmagnetic sensors have excessive noise for this application. We report on the development of a non-magnetic inertial sensor, and on a novel commercial sensor both of which have demonstrated the required noise levels for this application.

  4. Non-magnetic simplified cylindrical cloak with suppressed zero-th order scattering

    CERN Document Server

    Yan, Wei; Qiu, Min

    2008-01-01

    A new type of simplified cloaks with matched exterior boundaries is proposed. The cloak uses non-magnetic material for the TM polarization and can function with a relatively thin thickness. It is shown that the $zero^{th}$ order scattering of such cloak is dominant among all cylindrical scattering terms. A gap is added at the cloak's inner surface to eliminate the zero-th order scattering, through the mechanism of scattering resonance. The reduction in scattering is relatively smooth, indicating that the proposed scattering reduction method has good tolerance to perturbations. Numerical simulations also confirm that the proposed structure has very low scattering.

  5. Magnetism of Rare-Earth Compounds with Non-Magnetic Crystal-Field Ground Levels

    Institute of Scientific and Technical Information of China (English)

    LIU Zhao-Sen

    2007-01-01

    @@ Among rare-earth compounds, there are many materials having non-magnetic crystal-field (CF) ground levels.To understand their magnetic behaviour at low temperatures, we study the effects of the CF levels and the Heisenberg-like coupling on the magnetic process of such a crystalline with mean-field and CF theory. It is found that the material can be magnetically ordered if the Heisenberg exchange is sufficiently strong. Additionally we obtain a condition for initial magnetic ordering, and derive a formula for estimating the Curie temperature if the ordering occurs.

  6. The space density and X-ray luminosity function of non-magnetic cataclysmic variables

    Science.gov (United States)

    Pretorius, Magaretha L.; Knigge, Christian

    2012-01-01

    We combine two complete, X-ray flux-limited surveys, the ROSAT Bright Survey (RBS) and the ROSAT North Ecliptic Pole (NEP) survey, to measure the space density (ρ) and X-ray luminosity function (Φ) of non-magnetic cataclysmic variables (CVs). The combined survey has a flux limit of FX≳ 1.1 × 10-12 erg cm-2 s-1 over most of its solid angle of just over ?, but is as deep as ≃10-14 erg cm-2 s-1 over a small area. The CV sample that we construct from these two surveys contains 20 non-magnetic systems. We carefully include all sources of statistical error in calculating ρ and Φ by using Monte Carlo simulations; the most important uncertainty proves to be the often large errors in distances estimates. If we assume that the 20 CVs in the combined RBS and NEP survey sample are representative of the intrinsic population, the space density of non-magnetic CVs is ?. We discuss the difficulty in measuring Φ in some detail - in order to account for biases in the measurement, we have to adopt a functional form for Φ. Assuming that the X-ray luminosity function of non-magnetic CVs is a truncated power law, we constrain the power-law index to -0.80 ± 0.05. It seems likely that the two surveys have failed to detect a large, faint population of short-period CVs, and that the true space density may well be a factor of 2 or 3 larger than what we have measured; this is possible, even if we only allow for undetected CVs to have X-ray luminosities in the narrow range 28.7 log(LX/erg s-1) < 29.7. However, ρ as high as 2 × 10-4 pc-3 would require that the majority of CVs has X-ray luminosities below LX= 4 × 1028 erg s-1 in the 0.5-2.0 keV band.

  7. Implementation of Cavity Perturbation Method for Determining Relative Permittivity of Non Magnetic Materials

    Directory of Open Access Journals (Sweden)

    FAHIM GOHARAWAN

    2017-04-01

    Full Text Available Techniques for the cavity measurement of the electrical characteristics of the materials are well established using the approximate method due to its simplicity in material insertion and fabrication. However, the exact method which requires more comprehensive mathematical analysis as well, owing to the practical difficulties for the material insertion, is not mostly used while performing the measurements as compared to approximate method in most of the works. In this work the comparative analysis of both the approximate as well as Exact method is performed and accuracy of the Exact method is established by performing the measurements of non-magnetic material Teflon within the cavity.

  8. A Convenient Storage Rack for Graduated Cylinders

    Science.gov (United States)

    Love, Brian

    2004-01-01

    An attempt is made to find a solution to the occasional problem of a need for storing large numbers of graduated cylinders in many teaching and research laboratories. A design, which involves the creation of a series of parallel channels that are used to suspend inverted graduated cylinders by their bases, is proposed.

  9. Optimization and improvement of Halbach cylinder design

    CERN Document Server

    Bjørk, R; Smith, A; Pryds, N

    2014-01-01

    In this paper we describe the results of a parameter survey of a 16 segmented Halbach cylinder in three dimensions in which the parameters internal radius, $r_{\\mathrm{\\scriptsize{in}}}$, external radius, $r_{\\mathrm{\\scriptsize{ex}}}$, and length, $L$, have been varied. Optimal values of $r_{\\mathrm{\\scriptsize{ex}}}$ and $L$ were found for a Halbach cylinder with the least possible volume of magnets with a given mean flux density in the cylinder bore. The volume of the cylinder bore could also be significantly increase by only slightly increasing the volume of the magnets, for a fixed mean flux density. Placing additional blocks of magnets on the end faces of the Halbach cylinder also improved the mean flux density in the cylinder bore, especially so for short Halbach cylinders with large $r_{\\mathrm{\\scriptsize{ex}}}$. Moreover magnetic cooling as an application for Halbach cylinders was considered. A magnetic cooling quality parameter, $\\Lambda_{\\mathrm{cool}}$, was introduced and results showed that this...

  10. NUMERICAL STUDY OF NATURAL CONVECTION FROM TWO PARALLEL HORIZONTAL CYLINDERS ENCLOSED BY CIRCULAR CYLINDER

    Directory of Open Access Journals (Sweden)

    Mahmood Husain Ali

    2013-05-01

    Full Text Available In this paper, numerical solution is presented for the steady state, two dimensional natural convection heat transfer from two parallel horizontal cylinders enclosed by circular cylinder. The inner cylinders are heated and maintained at constant surface temperature, while the outer cylinder is cooled at constant surface temperature. Boundary fitted coordinate system is used to solve governing equations. The vorticity-stream function and energy equations is solved using explicit finite deference method and stream function equation solved by successive iteration method. (20Deferent cases are studied cover rang of Rayleigh number from (1,000 to (25,000 based on the inner cylinder diameter. These cases study the effect of the  varying inner cylinders position horizontally and vertically within outer cylinder on the heat transfer and buoyancy that causes the flow. Outputs are displayed in terms of streamline, isothermal contours and local and average Nusselt number. The results showed that the position of the inner cylinders highly affects the heat transfer and flow movements in the gap. At low Rayleigh numbers the average Nusselt number increases with increase of horizontal distance between inner cylinders but the state is reversed at high Rayleigh numbers, while the average Nusselt number is increases with inner cylinder moving down at all Rayleigh numbers. The optimal position of inner cylinders for maximum and minimum heat transfer is located at each Rayleigh number so can be employed in isolation process or cooling process.

  11. The development of glossopharyngeal breathing and palatal myoclonus in a 29 year old after scuba diving

    Directory of Open Access Journals (Sweden)

    Thomas AR

    2011-02-01

    Full Text Available Palatal myoclonus is a rare movement disorder characterized by brief, rhythmic involuntary movements of the soft palate. Palatal myoclonus is further subdivided into “essential palatal tremor” (EPT and “symptomatic palatal tremor” (SPT. EPT is characterized by involvement of the tensor veli palatini, myoclonus that might persist during sleep, as well as ear clicks, usually the patient’s presenting complaint. The MRI and neurological exam are normal in EPT. SPT is characterized by involvement of the levator veli palatini and myoclonus which consistently perseveres during sleep. The MRI shows olivary hypertrophy and clinical features may include ataxia, dysarthria and nystagmus, depending on the size of the lesion1. Glossopharyngeal breathing is a technique used by deep-sea divers to increase lung vital capacity, which is also useful in patients with ventilator dependence from poliomyelitis and Duchenne muscular dystrophy. To date there have been no reported cases of palatal myoclonus and glossopharyngeal breathing occurring simultaneously. We present the case of a 29 year-old female with palatal myoclonus and glossopharyngeal breathing after scuba-diving.

  12. The Hawaii SCUBA-2 Lensing Cluster Survey: Number Counts and Submillimeter Flux Ratios

    CERN Document Server

    Hsu, Li-Yen; Chen, Chian-Chou; Barger, Amy; Wang, Wei-Hao

    2016-01-01

    We present deep number counts at 450 $\\mu$m and 850 $\\mu$m using the SCUBA-2 camera on the James Clerk Maxwell Telescope. We combine data for six lensing cluster fields and three blank fields to measure the counts over a wide flux range at each wavelength. Thanks to the lensing magnification, our measurements extends to fluxes fainter than 1 mJy and 0.2 mJy at 450 $\\mu$m and 850 $\\mu$m, respectively. Our combined data highly constrain the faint end of the number counts. Integrating our counts shows that the majority of the extragalactic background light (EBL) at each wavelength is contributed by faint sources with $L_{\\rm IR} < 10^{12} L_{\\odot }$, corresponding to luminous infrared galaxies (LIRGs) or normal galaxies. By comparing our result with the 500 $\\mu$m stacking of $K$-selected sources from the literature, we conclude that the $K$-selected LIRGs and normal galaxies still cannot fully account for the EBL that originates from sources with $L_{\\rm IR} < 10^{12} L_{\\odot }$. This suggests that many...

  13. The JCMT Gould Belt Survey: A Quantitative Comparison Between SCUBA-2 Data Reduction Methods

    CERN Document Server

    Mairs, S; Kirk, H; Graves, S; Buckle, J; Beaulieu, S F; Berry, D S; Broekhoven-Fiene, H; Currie, M J; Fich, M; Hatchell, J; Jenness, T; Mottram, J C; Nutter, D; Pattle, K; Pineda, J E; Salji, C; Di Francesco, J; Hogerheijde, M R; Ward-Thompson, D

    2015-01-01

    Performing ground-based submillimetre observations is a difficult task as the measurements are subject to absorption and emission from water vapour in the Earth's atmosphere and time variation in weather and instrument stability. Removing these features and other artifacts from the data is a vital process which affects the characteristics of the recovered astronomical structure we seek to study. In this paper, we explore two data reduction methods for data taken with the Submillimetre Common-User Bolometer Array-2 (SCUBA-2) at the James Clerk Maxwell Telescope (JCMT). The JCMT Legacy Reduction 1 (JCMT LR1) and The Gould Belt Legacy Survey Legacy Release 1 (GBS LR1) reduction both use the same software, Starlink, but differ in their choice of data reduction parameters. We find that the JCMT LR1 reduction is suitable for determining whether or not compact emission is present in a given region and the GBS LR1 reduction is tuned in a robust way to uncover more extended emission, which better serves more in-depth ...

  14. A SCUBA survey of Orion, the low-mass end of the core mass function

    CERN Document Server

    Nutter, D

    2006-01-01

    We have re-analysed all of the SCUBA archive data of the Orion star-forming regions. We have put together all of the data taken at different times by different groups. Consequently we have constructed the deepest submillimetre maps of these regions ever made. There are four regions that have been mapped: Orion A North & South, and Orion B North & South. We find that two of the regions, Orion A North and Orion B North, have deeper sensitivity and completeness limits, and contain a larger number of sources, so we concentrate on these two. We compare the data with archive data from the Spitzer Space Telescope to determine whether or not a core detected in the submillimetre is pre-stellar in nature. We extract all of the pre-stellar cores from the data and make a histogram of the core masses. This can be compared to the stellar initial mass function (IMF). We find the high-mass core mass function follows a roughly Salpeter-like slope, just like the IMF, as seen in previous work. Our deeper maps allow us t...

  15. The SCUBA-2 Cosmology Legacy Survey: the clustering of submillimetre galaxies in the UKIDSS UDS field

    Science.gov (United States)

    Wilkinson, Aaron; Almaini, Omar; Chen, Chian-Chou; Smail, Ian; Arumugam, Vinodiran; Blain, Andrew; Chapin, Edward L.; Chapman, Scott C.; Conselice, Christopher J.; Cowley, William I.; Dunlop, James S.; Farrah, Duncan; Geach, James; Hartley, William G.; Ivison, Rob J.; Maltby, David T.; Michałowski, Michał J.; Mortlock, Alice; Scott, Douglas; Simpson, Chris; Simpson, James M.; van der Werf, Paul; Wild, Vivienne

    2017-01-01

    Submillimetre galaxies (SMGs) are among the most luminous dusty galaxies in the Universe, but their true nature remains unclear; are SMGs the progenitors of the massive elliptical galaxies we see in the local Universe, or are they just a short-lived phase among more typical star-forming galaxies? To explore this problem further, we investigate the clustering of SMGs identified in the SCUBA-2 Cosmology Legacy Survey. We use a catalogue of submillimetre (850 μm) source identifications derived using a combination of radio counterparts and colour/infrared selection to analyse a sample of 610 SMG counterparts in the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Survey (UKIDSS) Ultra Deep Survey (UDS), making this the largest high-redshift sample of these galaxies to date. Using angular cross-correlation techniques, we estimate the halo masses for this large sample of SMGs and compare them with passive and star-forming galaxies selected in the same field. We find that SMGs, on average, occupy high-mass dark matter haloes (Mhalo > 1013 M⊙) at redshifts z > 2.5, consistent with being the progenitors of massive quiescent galaxies in present-day galaxy clusters. We also find evidence of downsizing, in which SMG activity shifts to lower mass haloes at lower redshifts. In terms of their clustering and halo masses, SMGs appear to be consistent with other star-forming galaxies at a given redshift.

  16. The SCUBA-2 Cosmology Legacy Survey: The clustering of submillimetre galaxies in the UKIDSS UDS field

    CERN Document Server

    Wilkinson, Aaron; Chen, Chian-Chou; Smail, Ian; Arumugam, Vinodiran; Blain, Andrew; Chapin, Edward L; Chapman, Scott C; Conselice, Christopher J; Cowley, William I; Dunlop, James S; Farrah, Duncan; Geach, James; Hartley, William G; Ivison, Rob J; Maltby, David T; Michałowski, Michał J; Mortlock, Alice; Scott, Douglas; Simpson, Chris; Simpson, James M; van der Werf, Paul; Wild, Vivienne

    2016-01-01

    Submillimetre galaxies (SMGs) are among the most luminous dusty galaxies in the Universe, but their true nature remains unclear; are SMGs the progenitors of the massive elliptical galaxies we see in the local Universe, or are they just a short-lived phase among more typical star-forming galaxies? To explore this problem further, we investigate the clustering of SMGs identified in the SCUBA-2 Cosmology Legacy Survey. We use a catalogue of submillimetre ($850\\mu$m) source identifications derived using a combination of radio counterparts and colour/IR selection to analyse a sample of 914 SMGs in the UKIDSS Ultra Deep Survey (UDS), making this the largest high redshift sample of these galaxies to date. Using angular cross-correlation techniques, we estimate the halo masses for this large sample of SMGs and compare them with passive and star-forming galaxies selected in the same field. We find that SMGs, on average, occupy high-mass dark matter halos (M$_{\\text{halo}} >10^{13}$M$_{\\odot}$) at redshifts $z > 2.5$, ...

  17. Epilepsy, scuba diving and risk assessment. Near misses and the need for ongoing vigilance.

    Science.gov (United States)

    Smart, David; Lippmann, John

    2013-03-01

    There is ongoing debate about the safety of scuba diving for individuals with a history of epilepsy. An in-water seizure is highly likely to be fatal. Recommendations for fitness to dive vary with some regarding epilepsy as an absolute contraindication to diving (South Pacific Underwater Medicine Society) and others permitting diving under strict criteria (United Kingdom Sport Diving Medical Committee) with diving to be postponed for a period of three to five years without seizures. Long-term follow up of people with epilepsy shows that at least one-third will have a recurrence and that the risk remains elevated for many years. We present three cases where individuals with a history of epilepsy (or likely epilepsy) almost fell through the cracks of health risk assessment, two with near-fatal consequences. These cases inform the on-going debate about fitness to dive for those with current or past epilepsy, and highlight the importance of education for doctors, dive professionals and divers about the risks associated with epilepsy and diving.

  18. The SCUBA 8-mJy survey - I Sub-millimetre maps, sources and number counts

    CERN Document Server

    Scott, S; Dunlop, J; Serjeant, S; Peacock, J; Ivison, R J; Oliver, S; Mann, R; Lawrence, A; Efstathiou, A; Rowan-Robinson, M; Hughes, D; Archibald, E; Blain, A W; Longair, M

    2002-01-01

    We present maps, source lists, and number counts from the largest, unbiassed, extragalactic sub-mm survey so far undertaken with the SCUBA camera on the JCMT. Our maps cover 260 sq. arcmin, to a noise level S(850)=2.5 mJy/beam. We have reduced the data using both SURF, and our own pipeline which produces zero-footprint maps and noise images. The uncorrelated noise maps produced by the latter approach have allowed application of a maximum-likelihood method to measure the statistical significance of each peak, leading to properly quantified flux-density errors for all potential sources. We detect 19 sources with S/N > 4, 38 with S/N > 3.5, and 72 with S/N > 3. To assess completeness and the impact of source confusion we have applied our source extraction algorithm to a series of simulated images. The result is a new estimate of the sub-mm source counts in the flux-density range S(850)=5-15mJy, which we compare with other estimates, and with model predictions. Our estimate of the cumulative source count at S(850...

  19. A SCUBA-2 850-$\\mu$m survey of circumstellar disks in the $\\lambda$ Orionis cluster

    CERN Document Server

    Ansdell, Megan; Cieza, Lucas A

    2015-01-01

    We present results from an 850-$\\mu$m survey of the $\\sim$ 5 Myr old $\\lambda$ Orionis star-forming region. We used the SCUBA-2 camera on the James Clerk Maxwell Telescope to survey a $\\sim$0.5-diameter circular region containing 36 (out of 59) cluster members with infrared excesses indicative of circumstellar disks. We detected only one object at $>3\\sigma$ significance, the Herbig Ae star HD 245185, with a flux density of $\\sim74$ mJy beam$^{-1}$ corresponding to a dust mass of $\\sim150$ M$_{\\oplus}$. Stacking the individually undetected sources did not produce a significant mean signal but gives an upper limit on the average dust mass for $\\lambda$ Orionis disks of $\\sim3$ M$_{\\oplus}$. Our follow-up observations of HD 245185 with the Submillimeter Array found weak CO 2--1 line emission with an integrated flux of $\\sim170$ mJy km s$^{-1}$ but no $^{13}$CO or C$^{18}$O isotopologue emission at 30 mJy km s$^{-1}$ sensitivity, suggesting a gas mass of $\\lesssim1$ M$_{\\rm Jup}$. The implied gas-to-dust ratio i...

  20. Underwater Acoustic Source Localisation Among Blind and Sighted Scuba Divers: Comparative study

    Directory of Open Access Journals (Sweden)

    Jacopo Cambi

    2017-06-01

    Full Text Available Objectives: Many blind individuals demonstrate enhanced auditory spatial discrimination or localisation of sound sources in comparison to sighted subjects. However, this hypothesis has not yet been confirmed with regards to underwater spatial localisation. This study therefore aimed to investigate underwater acoustic source localisation among blind and sighted scuba divers. Methods: This study took place between February and June 2015 in Elba, Italy, and involved two experimental groups of divers with either acquired (n = 20 or congenital (n = 10 blindness and a control group of 30 sighted divers. Each subject took part in five attempts at an under-water acoustic source localisation task, in which the divers were requested to swim to the source of a sound originating from one of 24 potential locations. The control group had their sight obscured during the task. Results: The congenitally blind divers demonstrated significantly better underwater sound localisation compared to the control group or those with acquired blindness (P = 0.0007. In addition, there was a significant correlation between years of blindness and underwater sound localisation (P <0.0001. Conclusion: Congenital blindness was found to positively affect the ability of a diver to recognise the source of a sound in an underwater environment. As the correct localisation of sounds underwater may help individuals to avoid imminent danger, divers should perform sound localisation tests during training sessions.

  1. The JCMT Gould Belt Survey: SCUBA-2 observations of circumstellar disks in L 1495

    CERN Document Server

    Buckle, J V; Greaves, J; Richer, J S; Matthews, B C; Johnstone, D; Kirk, H; Beaulieu, S F; Berry, D S; Broekhoven-Fiene, H; Currie, M J; Fich, M; Hatchell, J; Jenness, T; Mottram, J C; Nutter, D; Pattle, K; Pineda, J E; Salji, C; Tisi, S; Di Francesco, J; Hogerheijde, M R; Ward-Thompson, D; Bastien, P; Butner, H; Chen, M; Chrysostomou, A; Coude, S; Davis, C J; Duarte-Cabral, A; Friberg, P; Friesen, R; Fuller, G A; Graves, S; Gregson, J; Holland, W; Joncas, G; Kirk, J M; Knee, L B G; Mairs, S; Marsh, K; Moriarty-Schieven, G; Rawlings, J; Rosolowsky, E; Rumble, D; Sadavoy, S; Thomas, H; Tothill, N; Viti, S; White, G J; Wilson, C D; Wouterloot, J; Yates, J; Zhu, M

    2015-01-01

    We present 850$\\mu$m and 450$\\mu$m data from the JCMT Gould Belt Survey obtained with SCUBA-2 and characterise the dust attributes of Class I, Class II and Class III disk sources in L1495. We detect 23% of the sample at both wavelengths, with the detection rate decreasing through the Classes from I--III. The median disk mask is 1.6$\\times 10^{-3}$M$_{\\odot}$, and only 7% of Class II sources have disk masses larger than 20 Jupiter masses. We detect a higher proportion of disks towards sources with stellar hosts of spectral type K than spectral type M. Class II disks with single stellar hosts of spectral type K have higher masses than those of spectral type M, supporting the hypothesis that higher mass stars have more massive disks. Variations in disk masses calculated at the two wavelengths suggests there may be differences in dust opacity and/or dust temperature between disks with hosts of spectral types K to those with spectral type M.

  2. Quantum walk on a cylinder

    CERN Document Server

    Bru, Luis A; Di Molfetta, Giuseppe; Pérez, Armando; Roldán, Eugenio; Silva, Fernando

    2016-01-01

    We consider the 2D alternate quantum walk on a cylinder. We concentrate on the study of the motion along the open dimension, in the spirit of looking at the closed coordinate as a small or "hidden" extra dimension. If one starts from localized initial conditions on the lattice, the dynamics of the quantum walk that is obtained after tracing out the small dimension shows the contribution of several components, which can be understood from the study of the dispersion relations for this problem. In fact, these components originate from the contribution of the possible values of the quasi-momentum in the closed dimension. In the continuous space-time limit, the different components manifest as a set of Dirac equations, with each quasi-momentum providing the value of the corresponding mass. We briefly discuss the possible link of these ideas to the simulation of high energy physical theories that include extra dimensions.

  3. Quantifying absolute spin polarization with non-magnetic contacts in FM/ n-GaAs heterostructures

    Science.gov (United States)

    Geppert, Chad; Wienkes, Lee; Christie, Kevin; Patel, Sahil; Palmstrøm, Chris; Crowell, Paul

    2014-03-01

    We report on a novel method of quantifying spin accumulation in Co2MnSi/ n-GaAs and Fe/ n-GaAs heterostructures using a non-magnetic probe. The presence of a non-equilibrium spin polarization generates a large electrostatic potential shift relative to the equilibrium state. This is due to the combination of (1) the parabolic (non-constant) density of states and (2) the population imbalance between the two spin sub-bands. We observe this shift as a Hanle effect in a non-local, non-magnetic semiconducting contact. Since this signal depends only on experimentally accessible parameters of the bulk semiconductor, its magnitude may be used to quantify the injected spin polarization in absolute terms. By comparison with the (smaller) spin-valve signal observed with a second ferromagnetic contact, we demonstrate that this electrostatic shift scales quadratically with spin polarization, dephases in the presence of both applied and hyperfine fields, and is observable to higher temperatures than traditional non-local measurements. Quantitative modeling allows extraction of absolute polarizations in excess of 50 % at low temperatures, and further indicates that this contribution constitutes a large fraction of the three-terminal signal observed in these devices. Supported by NSF DMR-1104951; by STARnet, a SRC program sponsored by MARCO and DARPA; and by the NSF MRSEC program.

  4. Kramers non-magnetic superconductivity in LnNiAsO superconductors.

    Science.gov (United States)

    Li, Yuke; Luo, Yongkang; Li, Lin; Chen, Bin; Xu, Xiaofeng; Dai, Jianhui; Yang, Xiaojun; Zhang, Li; Cao, Guanghan; Xu, Zhu-an

    2014-10-22

    We investigated a series of nickel-based oxyarsenides LnNiAsO (Ln=La, Ce, Pr, Nd, Sm) compounds. CeNiAsO undergoes two successive anti-ferromagnetic transitions at TN1=9.3 K and TN2=7.3 K; SmNiAsO becomes an anti-ferromagnet below TN≃3.5 K; NdNiAsO keeps paramagnetic down to 2 K but orders anti-ferromagnetically below TN≃1.3 K. Superconductivity was observed only in Kramers non-magnetic LaNiAsO and PrNiAsO with Tc=2.7 K and 0.93 K, respectively. The superconductivity of PrNiAsO is further studied by upper critical field and specific heat measurements, which reveal that PrNiAsO is a weakly coupled Kramers non-magnetic superconductor. Our work confirms that the nickel-based oxyarsenide superconductors are substantially different in mechanism to iron-based ones, and are likely to be described by the conventional superconductivity theory.

  5. Component masses of young, wide, non-magnetic white dwarf binaries in the SDSS DR7

    CERN Document Server

    Baxter, R B; Parker, Q A; Casewell, S L; Lodieu, N; Burleigh, M R; Lawrie, K A; Kulebi, B; Koester, D; Holland, B R

    2014-01-01

    We present a spectroscopic component analysis of 18 candidate young, wide, non-magnetic, double-degenerate binaries identified from a search of the Sloan Digital Sky Survey Data Release 7 (DR7). All but two pairings are likely to be physical systems. We show SDSS J084952.47+471247.7 + SDSS J084952.87+471249.4 to be a wide DA+DB binary, only the second identified to date. Combining our measurements for the components of 16 new binaries with results for three similar, previously known systems within the DR7, we have constructed a mass distribution for the largest sample to date (38) of white dwarfs in young, wide, non-magnetic, double-degenerate pairings. This is broadly similar in form to that of the isolated field population with a substantial peak around M~0.6 Msun. We identify an excess of ultra-massive white dwarfs and attribute this to the primordial separation distribution of their progenitor systems peaking at relatively larger values and the greater expansion of their binary orbits during the final sta...

  6. Non-magnetic impurity effects in LiFeAs studied by STM/STS

    Science.gov (United States)

    Hanaguri, T.; Khim, Seung Hyun; Lee, Bumsung; Kim, Kee Hoon; Kitagawa, K.; Matsubayashi, K.; Mazaki, Y.; Uwatoko, Y.; Takigawa, M.; Takagi, H.

    2012-02-01

    Detecting the possible sign reversal of the superconducting gap in iron-based superconductors is highly non-trivial. Here we use non-magnetic impurity as a sign indicator. If the sign of the superconducting gap is positive everywhere in momentum space, in-gap bound state should not be observed near the impurity site unless it is magnetic. On the other hand, if there is a sign-reversal in the gap, even non-magnetic impurity may create in-gap bound state [1]. We performed STM/STS experiments on self-flux and Sn-flux grown LiFeAs crystals and examined the effects of Sn impurity. In STM images of Sn-flux grown samples, we found a ring-like object which may represent Sn. Tunneling spectrum taken at this defect site exhibits in-gap bound state. Together with flat-bottom superconducting gap observed far from the defects, sign-reversing s-wave gap is the most plausible gap structure in LiFeAs. [1] T. Kariyado and M. Ogata, JPSJ 79, 083704 (2010).

  7. VORTEX INDUCED VIBRATIONS OF FINNED CYLINDERS

    Institute of Scientific and Technical Information of China (English)

    SHA Yong; WANG Yong-xue

    2008-01-01

    This article presents the results of a numerical simulation on the vortex induced vibration of various finned cylinders at low Reynolds number. The non-dimensional, incompressible Navier-Stokes equations and continuity equation were adopted to simulate the fluid around the cylinder. The cylinder (with or without fins) in fluid flow was approximated as a mass-spring system. The fluid-body interaction of the cylinder with fins and uniform flow was numerically simulated by applying the displacement and stress iterative computation on the fluid-body interfaces. Both vortex structures and response amplitudes of cylinders with various arrangements of fins were analyzed and discussed. The remarkable decrease of response amplitude for the additions of Triangle60 fins and Quadrangle45 fins was found to be comparable with that of bare cylinder. However, the additions of Triangle00 fins and Quadrangle00 fins enhance the response amplitude greatly. Despite the assumption of two-dimensional laminar flow, the present study can give a good insight into the phenomena of cylinders with various arrangements of fins.

  8. Expansion of Metallic Cylinders under Explosive Loading

    Directory of Open Access Journals (Sweden)

    M.S. Bola

    1992-07-01

    Full Text Available The behaviour of expanding metallic cylinders under explosive loading was studied. Using ultra high speed photography, the expansion characteristics of aluminium and copper metallic cylinders have been evaluated with different c/m ratio, and by changing the nature of high explosive. The results obtained are comparable to those predicted by the Gurney's energy and momentum balance equations. A cylinder test has been established for comparative to the metal by octol, TNT, PEK-1, baratol and composition B are calculated. The results are in close agreement with those calculated by Kury et al.

  9. A Submillimeter Perspective on the GOODS Fields (SUPER GOODS). I. An Ultradeep SCUBA-2 Survey of the GOODS-N

    Science.gov (United States)

    Cowie, L. L.; Barger, A. J.; Hsu, L.-Y.; Chen, Chian-Chou; Owen, F. N.; Wang, W.-H.

    2017-03-01

    In this first paper in the SUPER GOODS series on powerfully star-forming galaxies in the two GOODS fields, we present a deep SCUBA-2 survey of the GOODS-N at both 850 and 450 μm (central rms noise of 0.28 mJy and 2.6 mJy, respectively). In the central region, the 850 μm observations cover the GOODS-N to near the confusion limit of ∼1.65 mJy, while over a wider 450 arcmin2 region—well complemented by Herschel far-infrared imaging—they have a median 4σ limit of 3.5 mJy. We present ≥slant 4σ catalogs of 186 850 μm and 31 450 μm selected sources. We use interferometric observations from the Submillimeter Array (SMA) and the Karl G. Jansky Very Large Array (VLA) to obtain precise positions for 114 SCUBA-2 sources (28 from the SMA, all of which are also VLA sources). We present new spectroscopic redshifts and include all existing spectroscopic or photometric redshifts. We also compare redshifts estimated using the 20 cm/850 μm and the 250 cm/850 μm flux ratios. We show that the redshift distribution increases with increasing flux, and we parameterize the dependence. We compute the star formation history and the star formation rate (SFR) density distribution functions in various redshift intervals, finding that they reach a peak at z=2{--}3 before dropping to higher redshifts. We show that the number density per unit volume of {SFR} ≳ 500 {M}ȯ {{yr}}-1 galaxies measured from the SCUBA-2 sample does not change much relative to that of lower SFR galaxies from UV selected samples over z=2{--}5, suggesting that, apart from changes in the normalization, the shape in the number density as a function of SFR is invariant over this redshift interval.

  10. The JCMT Gould Belt Survey: a first look at Southern Orion A with SCUBA-2

    Science.gov (United States)

    Mairs, S.; Johnstone, D.; Kirk, H.; Buckle, J.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Graves, S.; Hatchell, J.; Jenness, T.; Mottram, J. C.; Nutter, D.; Pattle, K.; Pineda, J. E.; Salji, C.; Di Francesco, J.; Hogerheijde, M. R.; Ward-Thompson, D.; Bastien, P.; Bresnahan, D.; Butner, H.; Chen, M.; Chrysostomou, A.; Coudé, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Mowat, C.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Rumble, D.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wouterloot, J.; Yates, J.; Zhu, M.

    2016-10-01

    We present the JCMT Gould Belt Survey's first look results of the southern extent of the Orion A Molecular Cloud (δ ≤ -5:31:27.5). Employing a two-step structure identification process, we construct individual catalogues for large-scale regions of significant emission labelled as islands and smaller-scale subregions called fragments using the 850 μm continuum maps obtained using SCUBA-2. We calculate object masses, sizes, column densities, and concentrations. We discuss fragmentation in terms of a Jeans instability analysis and highlight interesting structures as candidates for follow-up studies. Furthermore, we associate the detected emission with young stellar objects (YSOs) identified by Spitzer and Herschel. We find that although the population of active star-forming regions contains a wide variety of sizes and morphologies, there is a strong positive correlation between the concentration of an emission region and its calculated Jeans instability. There are, however, a number of highly unstable subregions in dense areas of the map that show no evidence of star formation. We find that only ˜72 per cent of the YSOs defined as Class 0+I and flat-spectrum protostars coincide with dense 850 μm emission structures (column densities >3.7 × 1021 cm-2). The remaining 28 per cent of these objects, which are expected to be embedded in dust and gas, may be misclassified. Finally, we suggest that there is an evolution in the velocity dispersion of YSOs such that sources which are more evolved are associated with higher velocities.

  11. Properties of the Scuba-2 850 μm Sources in the XMM-LSS Field

    Science.gov (United States)

    Seo, Hyunjong; Jeong, Woong-Seob; Kim, Seong Jin; Pyo, Jeonghyun; Kim, Min Gyu; Ko, Jongwan; Kim, Minjin; Kim, Sam

    2017-02-01

    We carry out the study of 850 μm sources in a part of the XMM-LSS field. The 850 μm imaging data were obtained by the SCUBA-2 on the James Clerk Maxwell Telescope(JCMT) for three days in July 2015 with an integration time of 6.1 hours, covering a circular area with a radius of 15'. We choose the central area up to a radius of 9.15 arcmin for the study, where the noise distribution is relatively uniform. The root mean square (rms) noise at the center is 2.7 mJy. We identify 17 sources with S/N > 3.5. Differential number count is estimated in flux range between 3.5 and 9.0 mJy after applying various corrections derived by imaging simulations, which is consistent with previous studies. For detailed study on the individual sources, we select three sources with more reliable measurements (S/N > 4.5), and construct their spectral energy distributions (SEDs) from optical to far-infrared band. Redshift distribution of the sources ranges from 0.36 to 3.28, and their physical parameters are extracted using MAGPHYS model, which yield infrared luminosity L_{IR}= 10^{11.3}-10^{13.4} L_{⊙}, star formation rate SFR = 10^{1.3}-10^{3.2} M_{⊙}yr^{-1} and dust temperature T_{D} = 30-53 K. We investigate the correlation between L_{IR} and T_{D}, which appears to be consistent with previous studies.}

  12. Designing the coordinate transformation function for non-magnetic invisibility cloaking

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xiaofei; Feng Yijun; Zhao Lin; Jiang Tian [Department of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 (China); Lu Chunhua; Xu Zhongzi [College of Materials Science and Engineering, Nanjing University of Technology, Nanjing, 210009 (China)], E-mail: yjfeng@nju.edu.cn

    2008-11-07

    An optical invisibility cloak based on a transformation approach has recently been proposed by a reduced set of material properties due to their easier implementation in reality and little need for an inhomogeneous permeability distribution, but the drawback of undesired scattering caused by the impedance mismatching at the outer boundary is unavoidable in such a cloak. By properly designing the coordinate transformation function to ensure impedance matching at the outer surface, we show that the performance of a nonmagnetic cylindrical cloak could be improved with minimized scattering fields. Using either a single high order power function or an optimized piecewise continuous power function, a cylindrical non-magnetic cloak has been designed with nearly perfect cloaking performance, which is better than those generated with a linear or a quadratic function. Due to the monotonicity of the designed power functions, the resulting cloak has no restriction on the size of the cloaking shell, therefore is suitable for both thick and thin cloaking structures.

  13. Can reef conservation programmes help reducing SCUBA diving damage to coral reefs? A case study in Thailand

    OpenAIRE

    Mendes, Bruno Miguel Silvestre

    2008-01-01

    Dissertação de mestrado, Biologia Marinha (Ecologia e Conservação Marinha), Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2008 Coral reefs are under threat all over the world. Coastal human activities are not always sustainable in this vulnerable ecosystem and may produce continual and cumulative damage. At the present, Thailand is a main tourist destination for SCUBA divers from all around the world and this industry is having a big expansion in recent year...

  14. Non-magnetic photospheric bright points in 3D simulations of the solar atmosphere

    Science.gov (United States)

    Calvo, F.; Steiner, O.; Freytag, B.

    2016-11-01

    Context. Small-scale bright features in the photosphere of the Sun, such as faculae or G-band bright points, appear in connection with small-scale magnetic flux concentrations. Aims: Here we report on a new class of photospheric bright points that are free of magnetic fields. So far, these are visible in numerical simulations only. We explore conditions required for their observational detection. Methods: Numerical radiation (magneto-)hydrodynamic simulations of the near-surface layers of the Sun were carried out. The magnetic field-free simulations show tiny bright points, reminiscent of magnetic bright points, only smaller. A simple toy model for these non-magnetic bright points (nMBPs) was established that serves as a base for the development of an algorithm for their automatic detection. Basic physical properties of 357 detected nMBPs were extracted and statistically evaluated. We produced synthetic intensity maps that mimic observations with various solar telescopes to obtain hints on their detectability. Results: The nMBPs of the simulations show a mean bolometric intensity contrast with respect to their intergranular surroundings of approximately 20%, a size of 60-80 km, and the isosurface of optical depth unity is at their location depressed by 80-100 km. They are caused by swirling downdrafts that provide, by means of the centripetal force, the necessary pressure gradient for the formation of a funnel of reduced mass density that reaches from the subsurface layers into the photosphere. Similar, frequently occurring funnels that do not reach into the photosphere, do not produce bright points. Conclusions: Non-magnetic bright points are the observable manifestation of vertically extending vortices (vortex tubes) in the photosphere. The resolving power of 4-m-class telescopes, such as the DKIST, is needed for an unambiguous detection of them. The movie associated to Fig. 1 is available at http://www.aanda.org

  15. Invariance of the magnetic behavior and AMI in ferromagnetic biphase films with distinct non-magnetic metallic spacers

    Energy Technology Data Exchange (ETDEWEB)

    Silva, E.F. [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Gamino, M. [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Instituto de Física, Universidade Federal do Rio Grande de Sul, 91501-970 Porto Alegre, RS (Brazil); Andrade, A.M.H. de [Instituto de Física, Universidade Federal do Rio Grande de Sul, 91501-970 Porto Alegre, RS (Brazil); Vázquez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid (Spain); Correa, M.A. [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Bohn, F., E-mail: felipebohn@fisica.ufrn.br [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil)

    2017-02-01

    We investigate the quasi-static magnetic, magnetotransport, and dynamic magnetic properties in ferromagnetic biphase films with distinct non-magnetic metallic spacer layers. We observe that the nature of the non-magnetic metallic spacer material does not have significant influence on the overall biphase magnetic behavior, and, consequently, on the magnetotransport and dynamic magnetic responses. We focus on the magnetoimpedance effect and verify that the films present asymmetric magnetoimpedance effect. Moreover, we explore the possibility of tuning the linear region of the magnetoimpedance curves around zero magnetic field by varying the probe current frequency in order to achieve higher sensitivity values. The invariance of the magnetic behavior and the asymmetric magnetoimpedance effect in ferromagnetic biphase films with distinct non-magnetic metallic spacers place them as promising candidates for probe element and open possibilities to the development of lower-cost high sensitivity linear magnetic field sensor devices.

  16. Invariance of the magnetic behavior and AMI in ferromagnetic biphase films with distinct non-magnetic metallic spacers

    Science.gov (United States)

    Silva, E. F.; Gamino, M.; Andrade, A. M. H. de; Vázquez, M.; Correa, M. A.; Bohn, F.

    2017-02-01

    We investigate the quasi-static magnetic, magnetotransport, and dynamic magnetic properties in ferromagnetic biphase films with distinct non-magnetic metallic spacer layers. We observe that the nature of the non-magnetic metallic spacer material does not have significant influence on the overall biphase magnetic behavior, and, consequently, on the magnetotransport and dynamic magnetic responses. We focus on the magnetoimpedance effect and verify that the films present asymmetric magnetoimpedance effect. Moreover, we explore the possibility of tuning the linear region of the magnetoimpedance curves around zero magnetic field by varying the probe current frequency in order to achieve higher sensitivity values. The invariance of the magnetic behavior and the asymmetric magnetoimpedance effect in ferromagnetic biphase films with distinct non-magnetic metallic spacers place them as promising candidates for probe element and open possibilities to the development of lower-cost high sensitivity linear magnetic field sensor devices.

  17. Magnetohydrodynamic Flow Between Concentric Rotating Porous Cylinders

    Directory of Open Access Journals (Sweden)

    S. N. Dube

    1971-10-01

    Full Text Available An attempt has been made to study the steady laminar flow of a incompressible electrically conducting fluid between infinitely long concentric rotating porous cylinders under the influence of radial magnetic field. A solution has been obtained under the assumption of uniform conditions along the axis of the cylinders. The cylinders being porous, a hyperbolic radial velocity distribution has been superimposed over the circumferential velocity produced due to rotation. There is a Bernoulli type pressure variation in the radial in the direction. When the inner cylinder is at rest the shearing stress at it and the torque transmitted to it decrease as R (=v/Sub/1y/Sub1/v= v/Sub2y/Sub2/v increases and the magnetic parameter lambda (=4sigma mue/sube/sup2A/Sup2/Mue will further decrease them.

  18. Theory of interacting dislocations on cylinders.

    Science.gov (United States)

    Amir, Ariel; Paulose, Jayson; Nelson, David R

    2013-04-01

    We study the mechanics and statistical physics of dislocations interacting on cylinders, motivated by the elongation of rod-shaped bacterial cell walls and cylindrical assemblies of colloidal particles subject to external stresses. The interaction energy and forces between dislocations are solved analytically, and analyzed asymptotically. The results of continuum elastic theory agree well with numerical simulations on finite lattices even for relatively small systems. Isolated dislocations on a cylinder act like grain boundaries. With colloidal crystals in mind, we show that saddle points are created by a Peach-Koehler force on the dislocations in the circumferential direction, causing dislocation pairs to unbind. The thermal nucleation rate of dislocation unbinding is calculated, for an arbitrary mobility tensor and external stress, including the case of a twist-induced Peach-Koehler force along the cylinder axis. Surprisingly rich phenomena arise for dislocations on cylinders, despite their vanishing Gaussian curvature.

  19. Suppression of Brazier Effect in Multilayered Cylinders

    Directory of Open Access Journals (Sweden)

    Hiroyuki Shima

    2014-01-01

    Full Text Available When a straight hollow tube having circular cross-section is bent uniformly into an arc, the cross-section tends to ovalize or flatten due to the in-plane stresses induced by bending; this ovalization phenomenon is called the Brazier effect. The present paper is aimed at theoretical formulation of the Brazier effect observed in multilayered cylinders, in which a set of thin hollow cylinders are stacked concentrically about the common axis. The results indicate that mechanical couplings between stacked cylinders are found to yield pronounced suppression of the cross-sectional ovalization. Numerical computations have been performed to measure the degree of suppression in a quantitative manner and to explore how it is affected by the variations in the bending curvature, the number of stacked cylinders, and the interlayer coupling strength.

  20. Sub-wavelength resonances in polygonal metamaterial cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2008-01-01

    It has been shown that the sub-wavelength resonances of circular MTM cylinders also occur for polygonal MTM cylinders. This is the case for lossless and non-dispersive cylinders as well as lossy and dispersive cylinders. The sub-wavelength resonances are thus not limited to structures of canonical...

  1. Dynamic Fracture Simulations of Explosively Loaded Cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, Carly W. [Univ. of California, Davis, CA (United States). Dept. of Civil and Environmental Engineering; Goto, D. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-11-30

    This report documents the modeling results of high explosive experiments investigating dynamic fracture of steel (AerMet® 100 alloy) cylinders. The experiments were conducted at Lawrence Livermore National Laboratory (LLNL) during 2007 to 2008 [10]. A principal objective of this study was to gain an understanding of dynamic material failure through the analysis of hydrodynamic computer code simulations. Two-dimensional and three-dimensional computational cylinder models were analyzed using the ALE3D multi-physics computer code.

  2. W-76 PBX 9501 cylinder tests

    Energy Technology Data Exchange (ETDEWEB)

    Hill, L.G.; Catanach, R.A.

    1998-07-01

    Five 1-inch diameter cylinder tests were fired in support of the W-76 high explosive surveillance program. Three of the tests used baseline material, and two used stockpile return material. The diagnostics were electrical pins to measure detonation velocity and a streak camera to measure wall motion. The data was analyzed for cylinder energy, Gurney energy, and detonation velocity. The results of all three measures were consistent for all five tests, to within the experimental accuracy.

  3. Study of Multi-Cylinder Engine Manifolds

    Science.gov (United States)

    1944-10-31

    were developed so that mnifolds for any number of cylinders could be analyzed for max- I= zm volumetrie efficiency. Eletricaleebanioal analoCies can be...deceleration of the air& The vibrations are almot Identical to thse In single cylinder intake pipes. The mmi- a= volumetrie efficiency bould be...pipe 14 in. total volume 7- In- 3 area of pipew 0.86 in 2 Table I gives the actual and calculated speeds for peak volumetri efficiencies for a sIngle

  4. Statistical analyses of a screen cylinder wake

    Science.gov (United States)

    Mohd Azmi, Azlin; Zhou, Tongming; Zhou, Yu; Cheng, Liang

    2017-02-01

    The evolution of a screen cylinder wake was studied by analysing its statistical properties over a streamwise range of x/d={10-60}. The screen cylinder was made of a stainless steel screen mesh of 67% porosity. The experiments were conducted in a wind tunnel at a Reynolds number of 7000 using an X-probe. The results were compared with those obtained in the wake generated by a solid cylinder. It was observed that the evolution of the statistics in the wake of the screen cylinder was different from that of a solid cylinder, reflecting the differences in the formation of the organized large-scale vortices in both wakes. The streamwise evolution of the Reynolds stresses, energy spectra and cross-correlation coefficients indicated that there exists a critical location that differentiates the screen cylinder wake into two regions over the measured streamwise range. The formation of the fully formed large-scale vortices was delayed until this critical location. Comparison with existing results for screen strips showed that although the near-wake characteristics and the vortex formation mechanism were similar between the two wake generators, variation in the Strouhal frequencies was observed and the self-preservation states were non-universal, reconfirming the dependence of a wake on its initial condition.

  5. RESULTS RESULTING FROM AUTOFRETTAGE OF CYLINDER

    Institute of Scientific and Technical Information of China (English)

    ZHU Ruilin

    2008-01-01

    Autofrettage is used to introduce advantageous residual stresses into wall of a cylinder and to even distributions of total stresses. Basic theory on autofrettage has been functioning for several decades. It is necessary to reveal profound relations between parameters in the theory. Therefore, based on the 3rd strength theory, δei/δy, δei/δy, δei′/δy, δei′/δy and their relations, as well as p/δy, are studied under ideal conditions, where δei/δy is equivalent stress of total stresses at elastoplastic juncture/yield strength, δei/δy is equivalent stress of total stresses at inside surface/yield strength, δei′/δy is equivalent stress of residual stresses at elastoplastic juncture/yield strength, δei′/δy is equivalent stress of residual stresses at inside surface/yield strength, p/δy is load-bearing capacity of an autofrettaged cylinder/yield strength. Theoretical study on the parameters results in noticeable results and laws. The main idea is: to satisfy |δei′|=δy, the relation between kj and k is , where k is outside/inside radius ratio of a cylinder, kj is ratio of elastoplastic juncture radius to inside radius of a cylinder; when the plastic region covers the whole wall of a cylinder, for compressive yield not to occur after removing autofrettage pressure, the ultimate k is k=2.218 46, with k=2.218 46, a cylinder's ultimate load-bearing capacity equals its entire yield pressure, or =lnk; when kj≤=1.648 72, no matter how great k is, compressive yield never occurs after removing pa; the maximum and optimum load-bearing capacity of an autofrettaged cylinder is just two times the loading which an unautofrettaged cylinder can bear elastically, or , thus the limit of the load-bearing capacity of an autofrettaged cylinder is also just 2 times that of an unautofrettaged cylinder.

  6. The SCUBA-2 Cosmology Legacy Survey: Multi-wavelength Properties of ALMA-identified Submillimeter Galaxies in UKIDSS-UDS

    CERN Document Server

    Simpson, J M; Swinbank, A M; Ivison, R J; Dunlop, J S; Geach, J E; Almaini, O; Arumugam, V; Bremer, M N; Chen, Chian-Chou; Conselice, C; Coppin, K E K; Farrah, D; Ibar, E; Hartley, W G; Ma, C J; Michalowski, M J; Spaans, M; Thomson, A P; van der Werf, P P

    2016-01-01

    We present a multi-wavelength analysis of 52 sub-millimeter galaxies (SMGs), identified using ALMA 870$\\mu$m continuum imaging in a pilot program to precisely locate bright SCUBA2-selected sub-mm sources in the UKIDSS Ultra Deep Survey (UDS) field. Using the available deep (especially near-infrared), panoramic imaging of the UDS field at optical-to-radio wavelengths we characterize key properties of the SMG population. The median photometric redshift of the bright ALMA/SCUBA-2 UDS (AS2UDS) SMGs that are detected in a sufficient number of wavebands to derive a robust photometric redshift is $z$=2.65$\\pm$0.13. However, similar to previous studies, 27% of the SMGs are too faint at optical-to-near-infrared wavelengths to derive a reliable photometric redshift. Assuming that these SMGs lie at z$\\gtrsim$3 raises the median redshift of the full sample to $z$=2.9$\\pm$0.2. A subset of 23, unlensed, bright AS2UDS SMGs have sizes measured from resolved imaging of their rest-frame far-infrared emission. We show that the ...

  7. The SCUBA-2 Cosmology Legacy Survey: ALMA resolves the bright-end of the sub-millimeter number counts

    CERN Document Server

    Simpson, James; Swinbank, Mark; Chapman, Scott; Geach, James; Ivison, Rob; Thomson, Alasdair; Aretxaga, Itziar; Blain, Andrew; Cowley, Will; Chen, Chian-Chou; Coppin, Kristen; Dunlop, Jim; Edge, Alastair; Farrah, Duncan; Ibar, Edo; Karim, Alex; Knudsen, Kirsten; Meijerink, Rowin; Michalowski, Michal; Scott, Douglas; Spanns, Marco; van der Werf, Paul

    2015-01-01

    We present high-resolution 870-um ALMA continuum maps of 30 bright sub-millimeter sources in the UKIDSS UDS field. These sources are selected from deep, 1-square degrees 850-um maps from the SCUBA--2 Cosmology Legacy Survey, and are representative of the brightest sources in the field (median SCUBA2 flux S_850=8.7+/-0.4 mJy). We detect 52 sub-millimeter galaxies (SMGs) at >4-sigma significance in our 30 ALMA maps. In 61+/-17% of the ALMA maps the single-dish source comprises a blend of >=2 SMGs, where the secondary SMGs are Ultra--Luminous Infrared Galaxies (ULIRGs) with L_IR>10^12 Lo. The brightest SMG contributes on average 80+/-4% of the single-dish flux density, and in the ALMA maps containing >=2 SMGs the secondary SMG contributes 25+/-3% of the integrated ALMA flux. We construct source counts and show that multiplicity boosts the apparent single-dish cumulative counts by 20% at S_870>7.5mJy, and by 60% at S_870>12mJy. We combine our sample with previous ALMA studies of fainter SMGs and show that the cou...

  8. The JCMT Gould Belt Survey: the effect of molecular contamination in SCUBA-2 observations of Orion A

    CERN Document Server

    Coudé, S; Kirk, H; Johnstone, D; Drabek-Maunder, E; Graves, S; Hatchell, J; Chapin, E L; Gibb, A G; Matthews, B

    2016-01-01

    Thermal emission from cold dust grains in giant molecular clouds can be used to probe the physical properties, such as density, temperature and emissivity in star-forming regions. We present the SCUBA-2 shared-risk observations at 450 $\\mu$m and 850 $\\mu$m of the Orion A molecular cloud complex taken at the James Clerk Maxwell Telescope (JCMT). Previous studies showed that molecular emission lines can contribute significantly to the measured fluxes in those continuum bands. We use the HARP $^{12}$CO J=3-2 integrated intensity map for Orion A in order to evaluate the molecular line contamination and its effects on the SCUBA-2 maps. With the corrected fluxes, we have obtained a new spectral index $\\alpha$ map for the thermal emission of dust in the well-known integral-shaped filament. Furthermore, we compare a sample of 33 sources, selected over the Orion A molecular cloud complex for their high $^{12}$CO J=3-2 line contamination, to 27 previously identified clumps in OMC-4. This allows us to quantify the effec...

  9. Giant magneto-optical response in non-magnetic semiconductor BiTeI driven by bulk Rashba spin splitting

    OpenAIRE

    Demkó, L.; Schober, G. A. H.; Kocsis, V.; Bahramy, M.S.; Murakawa, H.; Lee, J. S.; Kézsmárki, I.; Arita, R.; Nagaosa, N.; Tokura, Y.

    2012-01-01

    We study the magneto-optical (MO) response of polar semiconductor BiTeI with giant bulk Rashba spin splitting at various carrier densities. Despite being non-magnetic, the material is found to yield a huge MO activity in the infrared region under moderate magnetic fields (

  10. Fabrication of a Textured Non-Magnetic Ni-12at.%V Alloy Substrate for Coated Conductors

    DEFF Research Database (Denmark)

    Gao, M. M.; Grivel, Jean-Claude; Suo, H. L.;

    2011-01-01

    Ni-12at.%V alloy is a promising candidate for non-magnetic cube textured metallic substrates used for high temperature coated conductors. In this work, a textured Ni-12at.%V substrate has been fabricated by powder metallurgy route. After cold rolling and recrystallization annealing, a cube texture...

  11. THE HERSCHEL AND JCMT GOULD BELT SURVEYS: CONSTRAINING DUST PROPERTIES IN THE PERSEUS B1 CLUMP WITH PACS, SPIRE, AND SCUBA-2

    Energy Technology Data Exchange (ETDEWEB)

    Sadavoy, S. I.; Di Francesco, J.; Johnstone, D.; Fallscheer, C.; Matthews, B. [Department of Physics and Astronomy, University of Victoria, P.O. Box 355, STN CSC, Victoria, BC V8W 3P6 (Canada); Currie, M. J.; Jenness, T. [Joint Astronomy Centre, 660 N. A' ohoku Place, University Park, Hilo, HI 96720 (United States); Drabek, E.; Hatchell, J. [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Nutter, D. [School of Physics and Astronomy, Cardiff University, Queen' s Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Andre, Ph.; Hennemann, M.; Hill, T.; Koenyves, V. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d' Astrophysique, Saclay, F-91191 Gif-sur-Yvette (France); Arzoumanian, D. [IAS, CNRS (UMR 8617), Universite Paris-Sud 11, Batiment 121, F-91400 Orsay (France); Benedettini, M. [Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, I-00133 Rome (Italy); Bernard, J.-P. [CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Duarte-Cabral, A. [Universite de Bordeaux, LAB, UMR 5804, F-33270 Floirac (France); Friesen, R. [Dunlap Institute, University of Toronto, Toronto, ON M5S 3H8 (Canada); Greaves, J. [School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS (United Kingdom); Collaboration: JCMT and Herschel Gould Belt Survey teams; and others

    2013-04-20

    We present Herschel observations from the Herschel Gould Belt Survey and SCUBA-2 science verification observations from the JCMT Gould Belt Survey of the B1 clump in the Perseus molecular cloud. We determined the dust emissivity index using four different techniques to combine the Herschel PACS+SPIRE data at 160-500 {mu}m with the SCUBA-2 data at 450 {mu}m and 850 {mu}m. Of our four techniques, we found that the most robust method was filtering out the large-scale emission in the Herschel bands to match the spatial scales recovered by the SCUBA-2 reduction pipeline. Using this method, we find {beta} Almost-Equal-To 2 toward the filament region and moderately dense material and lower {beta} values ({beta} {approx}> 1.6) toward the dense protostellar cores, possibly due to dust grain growth. We find that {beta} and temperature are more robust with the inclusion of the SCUBA-2 data, improving estimates from Herschel data alone by factors of {approx}2 for {beta} and by {approx}40% for temperature. Furthermore, we find core mass differences of {approx}< 30% compared to Herschel-only estimates with an adopted {beta} = 2, highlighting the necessity of long-wavelength submillimeter data for deriving accurate masses of prestellar and protostellar cores.

  12. Guided Circumferential Waves in Layered Poroelastic Cylinders

    Directory of Open Access Journals (Sweden)

    Shah S.A.

    2016-12-01

    Full Text Available The present paper investigates the propagation of time harmonic circumferential waves in a two-dimensional hollow poroelastic cylinder with an inner shaft (shaft-bearing assembly. The hollow poroelastic cylinder and inner shaft are assumed to be infinite in axial direction. The outer surface of the cylinder is stress free and at the interface, between the inner shaft and the outer cylinder, it is assumed to be free sliding and the interfacial shear stresses are zero, also the normal stress and radial displacements are continuous. The frequency equation of guided circumferential waves for a permeable and an impermeable surface is obtained. When the angular wave number vanish the frequency equation of guided circumferential waves for a permeable and an impermeable surface degenerates and the dilatational and shear waves are uncoupled. Shear waves are independent of the nature of surface. The frequency equation of a permeable and an impermeable surface for bore-piston assembly is obtained as a particular case of the model under consideration when the outer radius of the hollow poroelastic cylinder tends to infinity. Results of previous studies are obtained as a particular case of the present study. Nondimensional frequency as a function of wave number is presented graphically for two types of models and discussed. Numerical results show that, in general, the first modes are linear for permeable and impermeable surfaces and the frequency of a permeable surface is more than that of an impermeable surface.

  13. UF{sub 6} cylinder fire test

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.H. [Oak Ridge K-25 Site, Oak Ridge, TN (United States)

    1991-12-31

    With the increasing number of nuclear reactors for power generation, there is a comparable increase in the amount of UF{sub 6} being transported. Likewise, the probability of having an accident involving UF{sub 6}-filled cylinders also increases. Accident scenarios which have been difficult to assess are those involving a filled UF{sub 6} cylinder subjected to fire. A study is underway at the Oak Ridge K-25 Site, as part of the US DOE Enrichment Program, to provide empirical data and a computer model that can be used to evaluate various cylinder-in-fire scenarios. It is expected that the results will provide information leading to better handling of possible fire accidents as well as show whether changes should be made to provide different physical protection during shipment. The computer model being developed will be capable of predicting the rupture of various cylinder sizes and designs as well as the amount of UF{sub 6}, its distribution in the cylinder, and the conditions of the fire.

  14. Dynamic Simulation of the Harvester Boom Cylinder

    Directory of Open Access Journals (Sweden)

    Rongfeng Shen

    2017-04-01

    Full Text Available Based on the complete dynamic calculation method, the layout, force, and strength of harvester boom cylinders were designed and calculated. Closed simulations for the determination of the dynamic responses of the harvester boom during luffing motion considering the cylinder drive system and luffing angle position control have been realized. Using the ADAMS mechanical system dynamics analysis software, six different arm poses were selected and simulated based on the cylinder as the analysis object. A flexible model of the harvester boom luffing motion has been established. The movement of the oil cylinder under different conditions were analyzed, and the main operation dimensions of the harvester boom and the force condition of the oil cylinder were obtained. The calculation results show that the dynamic responses of the boom are more sensitive to the luffing acceleration, in comparison with the luffing velocity. It is seen that this method is very effective and convenient for boom luffing simulation. It is also reasonable to see that the extension of the distance of the bottom of the boom is shortened by adjusting the initial state of the boom in the working process, which can also effectively reduce the workload of the boom—thus improving the mechanical efficiency.

  15. Flexural vibrations of finite composite poroelastic cylinders

    Indian Academy of Sciences (India)

    Sandhya Rani Bandari; Srisailam Aleti; Malla Reddy Perati

    2015-04-01

    This paper deals with the flexural vibrations of composite poroelastic solid cylinder consisting of two cylinders that are bonded end to end. Poroelastic materials of the two cylinders are different. The frequency equations for pervious and impervious surfaces are obtained in the framework of Biot’s theory of wave propagation in poroelastic solids. The gauge invariance property is used to eliminate one arbitrary constant in the solution of the problem. This would lower the number of boundary conditions actually required. If the wavelength is infinite, frequency equations are degenerated as product of two determinants pertaining to extensional vibrations and shear vibrations. In this case, it is seen that the nature of the surface does not have any influence over shear vibrations unlike in the case of extensional vibrations. For illustration purpose, three composite cylinders are considered and then discussed. Of the three, two are sandstone cylinders and the third one is resulted when a cylindrical bone is implanted with Titanium. In either case, phase velocity is computed against aspect ratios.

  16. Base Stress of the Opened Bottom Cylinder Structures

    Institute of Scientific and Technical Information of China (English)

    刘建起; 孟晓娟

    2004-01-01

    The base stress of the opened bottom cylinder structure differs greatly from that of the structure with a closed bottom. By investigating the inner soil pressure on the cylinder wall and the base stress of the cylinder base, which were obtained from the model experiments, the interactions among the filler inside the cylinder,subsoil and cylinder are analyzed. The adjusting mechanism of frictional resistance between the inner filler and the wall of the cylinder during the overturning of the cylinder is discussed. Based on the experimental study, a method for calculating the base stress of the opened bottom cylinder structure is proposed. Meanwhile, the formulas for calculating the effective anti-overturning ratio of the opened bottom cylinder are derived.

  17. Chelating capture and magnetic removal of non-magnetic heavy metal substances from soil

    Science.gov (United States)

    Fan, Liren; Song, Jiqing; Bai, Wenbo; Wang, Shengping; Zeng, Ming; Li, Xiaoming; Zhou, Yang; Li, Haifeng; Lu, Haiwei

    2016-02-01

    A soil remediation method based on magnetic beneficiation is reported. A new magnetic solid chelator powder, FS@IDA (core-shell Fe3O4@SiO2 nanoparticles coated with iminodiacetic acid chelators), was used as a reactive magnetic carrier to selectively capture non-magnetic heavy metals in soil by chelation and removal by magnetic separation. FS@IDA was prepared via inorganic-organic and organic synthesis reactions that generated chelating groups on the surface of magnetic, multi-core, core-shell Fe3O4@SiO2 (FS) nanoparticles. These reactions used a silane coupling agent and sodium chloroacetate. The results show that FS@IDA could chelate the heavy metal component of Cd, Zn, Pb, Cu and Ni carbonates, lead sulfate and lead chloride in water-insoluble salt systems. The resulting FS@IDA-Cd and FS@IDA-Pb chelates could be magnetically separated, resulting in removal rates of approximately 84.9% and 72.2% for Cd and Pb, respectively. FS@IDA could not remove the residual heavy metals and those bound to organic matter in the soil. FS@IDA did not significantly alter the chemical composition of the soil, and it allowed for fast chelating capture, simple magnetic separation and facilitated heavy metal elution. FS@IDA could also be easily prepared and reprocessed.

  18. Are non-magnetic mechanisms such as temporal solar diameter variations conceivable for an irradiance variability?

    CERN Document Server

    Rozelot, J P; Pireaux, S; Ajabshirizadeh, A

    2004-01-01

    Irradiance variability has been monitored from space for more than two decades. Even if data are coming from different sources, it is well established that a temporal variability exists which can be set to as approximately 0.1%, in phase with the solar cycle. Today, one of the best explanation for such an irradiance variability is provided by the evolution of the solar surface magnetic fields. But if some 90 to 95% can be reproduced, what would be the origin of the 10 to 5% left? Non magnetic effects are conceivable. In this paper we will consider temporal variations of the diameter of the Sun as a possible contributor for the remaining part. Such an approach imposes strong constraints on the solar radius variability. We will show that over a solar cycle, variations of no more than 20 mas of amplitude can be considered. Such a variability (far from what is reported by observers conducting measurements by means of ground-based solar astrolabes) may explain a little part of the irradiance changes not explained ...

  19. Controlling magnetism on metal surfaces with non-magnetic means: electric fields and surface charging.

    Science.gov (United States)

    Brovko, Oleg O; Ruiz-Díaz, Pedro; Dasa, Tamene R; Stepanyuk, Valeri S

    2014-03-01

    We review the state of the art of surface magnetic property control with non-magnetic means, concentrating on metallic surfaces and techniques such as charge-doping or external electric field (EEF) application. Magneto-electric coupling via EEF-based charge manipulation is discussed as a way to tailor single adatom spins, exchange interaction between adsorbates or anisotropies of layered systems. The mechanisms of paramagnetic and spin-dependent electric field screening and the effect thereof on surface magnetism are discussed in the framework of theoretical and experimental studies. The possibility to enhance the effect of EEF by immersing the target system into an electrolyte or ionic liquid is discussed by the example of substitutional impurities and metallic alloy multilayers. A similar physics is pointed out for the case of charge traps, metallic systems decoupled from a bulk electron bath. In that case the charging provides the charge carrier density changes necessary to affect the magnetic moments and anisotropies in the system. Finally, the option of using quasi-free electrons rather than localized atomic spins for surface magnetism control is discussed with the example of Shockley-type metallic surface states confined to magnetic nanoislands.

  20. Flow interaction between a streamwise oscillating cylinder and a downstream stationary cylinder

    Science.gov (United States)

    Xu, S. J.; Gan, L.; Zhou, Y.

    2016-11-01

    In this paper, we present some experimental results about the physical effects of a cylinder's streamwise oscillation motion on a downstream one in a tandem arrangement. The upstream cylinder undergoes a controlled simple harmonic oscillation at amplitudes A/ d = 0.2-0.8, where d is the cylinder diameter, and the frequency ratio of f_e/f_s = 0-3.0, where f_e is the cylinder oscillation frequency and f_s is the natural frequency of vortex shedding from a single stationary cylinder. Under these conditions, the vortex shedding is locked to the controlled oscillation motion. Flow visualisation using the planar laser-induced fluorescence and qualitative measurements using hot-wire anemometry reveal three distinct flow regimes behind the downstream cylinder. For f_e/f_s > (f_e/f_s)_c, where (f_e/f_s)_c is a critical frequency ratio which depends on A/ d and Reynolds number Re, a so-called SA-mode occurs. The upstream oscillating cylinder generates binary vortices symmetrically arranged about the centreline, each containing a pair of counter-rotating vortices, and the downstream cylinder sheds vortices alternately at 0.5f_e. For 0.7-1.0 < f_e/f_s < (f_e/f_s)_c a complex vortex street that consists of two outer rows of vortices generated by the oscillating cylinder and two inner rows of vortices shed from the downstream stationary cylinder, which is referred to as AA-mode. For 0.3-0.6 < f_e/f_s< 0.8-1.0, one single staggered vortex street (A-mode) is observed. It is also found that, when f_e/f_s is near unity, the streamwise interaction of the two cylinders gives rise to the most energetic wake in the cross-stream direction, in terms of its maximum width, and the wake is AA-mode-like. The effects of other parameters such as the spacing between the two cylinders, Re and A/ d on the flow pattern are also discussed in details. The observations are further compared to the stationary tandem cylinder cases.

  1. Vortex noise from nonrotating cylinders and airfoils

    Science.gov (United States)

    Schlinker, R. H.; Amiet, R. K.; Fink, M. R.

    1976-01-01

    An experimental study of vortex-shedding noise was conducted in an acoustic research tunnel over a Reynolds-number range applicable to full-scale helicopter tail-rotor blades. Two-dimensional tapered-chord nonrotating models were tested to simulate the effect of spanwise frequency variation on the vortex-shedding mechanism. Both a tapered circular cylinder and tapered airfoils were investigated. The results were compared with data for constant-diameter cylinder and constant-chord airfoil models also tested during this study. Far-field noise, surface pressure fluctuations, and spanwise correlation lengths were measured for each configuration. Vortex-shedding noise for tapered cylinders and airfoils was found to contain many narrowband-random peaks which occurred within a range of frequencies corresponding to a predictable Strouhal number referenced to the maximum and minimum chord. The noise was observed to depend on surface roughness and Reynolds number.

  2. Sky reconstruction for the Tianlai cylinder array

    Science.gov (United States)

    Zhang, Jiao; Zuo, Shi-Fan; Ansari, Reza; Chen, Xuelei; Li, Yi-Chao; Wu, Feng-Quan; Campagne, Jean-Eric; Magneville, Christophe

    2016-10-01

    We apply our sky map reconstruction method for transit type interferometers to the Tianlai cylinder array. The method is based on spherical harmonic decomposition, and can be applied to a cylindrical array as well as dish arrays and we can compute the instrument response, synthesized beam, transfer function and noise power spectrum. We consider cylinder arrays with feed spacing larger than half a wavelength and, as expected, we find that the arrays with regular spacing have grating lobes which produce spurious images in the reconstructed maps. We show that this problem can be overcome using arrays with a different feed spacing on each cylinder. We present the reconstructed maps, and study the performance in terms of noise power spectrum, transfer function and beams for both regular and irregular feed spacing configurations.

  3. UF{sub 6} cylinder inspections at PGDP

    Energy Technology Data Exchange (ETDEWEB)

    Lamb, G.W.; Whinnery, W.N. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Routine inspections of all UF{sub 6} cylinders at the Paducah Gaseous Diffusion Plant have been mandated by the Department of Energy. A specific UF{sub 6} cylinder inspection procedure for what items to inspect and training for the operators prior to inspection duty are described. The layout of the cylinder yards and the forms used in the inspections are shown. The large number of cylinders (>30,000) to inspect and the schedule for completion on the mandated time table are discussed. Results of the inspections and the actions to correct the deficiencies are explained. Future inspections and movement of cylinders for relocation of certain cylinder yards are defined.

  4. Flow over an inline oscillating circular cylinder in the wake of a stationary circular cylinder

    Science.gov (United States)

    Zhang, Yang; Zhu, Keqiang

    2017-02-01

    Flow interference between an upstream stationary cylinder and an inline oscillating cylinder is studied with the lattice Boltzmann method. With a fixed Reynolds number Re = 100 and pitch ratio L/D = 4, the effects of oscillation amplitude A/D = [0.25, 1] and frequency f e/f s = [0.5, 2] are investigated. The wake response state is categorized into lock-in and non-lock-in. The lock-in zone in the bifurcation diagram of amplitude versus frequency is discontinuous. Response states of upstream and downstream wakes are similar under the conditions of small amplitude or low frequency. However, with large oscillating parameters, the two wakes are prone to be in different states as the flow field becomes irregular. Two distinct flow regimes have been identified, i.e., single-cylinder and two-cylinder shedding regimes. The presence of single-cylinder shedding regime is attributed to the low shedding frequency of the downstream cylinder at large amplitude. Hydrodynamic forces of the oscillating tandem system are discussed. The results reveal that forces on the two cylinders behave differently and that the absence of vortices in the gap flow significantly reduces the forces exerting on the tandem system.

  5. Casimir Energy for a Dielectric Cylinder

    CERN Document Server

    Cavero-Pelaez, I; Cavero-Pelaez, Ines; Milton, Kimball A.

    2004-01-01

    In this paper we calculate the Casimir energy for a dielectric-diamagnetic cylinder with the speed of light differing on the inside and outside. Although the result is in general divergent, special cases are meaningful. The well-known results for a uniform speed of light are reproduced. The self-stress on a purely dielectric cylinder is shown to vanish through second order in the deviation of the permittivity from its vacuum value, in agreement with the result calculated from the sum of van der Waals forces.

  6. Electromagnetic Invisibility of Elliptic Cylinder Cloaks

    Institute of Scientific and Technical Information of China (English)

    YAO Kan; LI Chao; LI Fang

    2008-01-01

    Structures with unique electromagnetic properties are designed based on the approach of spatial coordinate transformations of Maxwell's equations.This approach is applied to scheme out invisible elliptic cylinder cloaks,which provide more feasibility for cloaking arbitrarily shaped objects.The transformation expressions for the anisotropic material parameters and the field distribution are derived.The cloaking performances of ideal and lossy elliptic cylinder cloaks are investigated by finite element simulations. It is found that the cloaking performance will degrade in the forward direction with increasing loss.

  7. Stress tests on cylinders and aluminum panels

    Science.gov (United States)

    Sobel, L. H.; Agarwal, B. L.

    1974-01-01

    An optimization study of composite stiffened cylinders is discussed. The mathematical model for the buckling has been coupled successfully with the optimization program AESOP. The buckling analysis is based on the use of the smeared theory for the buckling of stiffened orthotropic cylindrical shells. The loading, radius, and length of the cylinder are assumed to be known parameters. An optimum solution gives the value of cross-sectional dimensions and laminate orientations. The different types of buckling modes are identified. Mathematical models are developed to show the relationships of the parameters.

  8. A Hybrid Approach To Tandem Cylinder Noise

    Science.gov (United States)

    Lockard, David P.

    2004-01-01

    Aeolian tone generation from tandem cylinders is predicted using a hybrid approach. A standard computational fluid dynamics (CFD) code is used to compute the unsteady flow around the cylinders, and the acoustics are calculated using the acoustic analogy. The CFD code is nominally second order in space and time and includes several turbulence models, but the SST k - omega model is used for most of the calculations. Significant variation is observed between laminar and turbulent cases, and with changes in the turbulence model. A two-dimensional implementation of the Ffowcs Williams-Hawkings (FW-H) equation is used to predict the far-field noise.

  9. EC Hidraulic Drive Cylinder Relief Vlave Test

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.; /Fermilab

    1991-04-03

    This engineering note documents the testing of the set pressure of the EC hydraulic drive cylinder relief valve. The purpose of the relief valve is to provide a safety measure in the event that oil becomes trapped in the rod side of the cylinder and pressure is applied to the cap side. The note includes an explanation of the procedure used and a summary of the result of the testing done on February 14, 1991 by Gary Trotter. The result was that the cylinder relief valve relieved at the correct set pressure of 10,500 psig. The basic concern is for the protection of the cylinder. The pump is capable of providing up to 10,500 psi of pressure to either side of the cylinder. The cylinder is rated for 10,500 psi. Under normal operating conditions, the valves would be open, and the pumping pressure would automatically flow oil into one side, and remove oil from the other side. If, however, the valve for the other side was closed, so that oil could not be removed, then the pressure would build in that side. If the rod side is pressurized to the maximum pump pressure of 10,500 psi, the cross sectional area ratio of 2.29 results in a pressure of approximately 4600 psi in the cap side, which is well under the rated pressure. If, however, the cap side is pressurized to 10,500 psi, the cross sectional area would produce a pressure of approximately 24,000 psi in the rod side, which could damage the cylinder. Therefore, the pressure on the rod side must be limited to the rated pressure of 10,500 psi. In reality, the maximum operating force on the piston would be under 11,000 Ibs., which would result in the maximum cylinder pressure being under 8000 psi to the rod side, and under 3500 psi to the cap side. Therefore, the relief is only needed as a safety precaution in the case that oil becomes trapped.

  10. Controllable parabolic-cylinder optical rogue wave.

    Science.gov (United States)

    Zhong, Wei-Ping; Chen, Lang; Belić, Milivoj; Petrović, Nikola

    2014-10-01

    We demonstrate controllable parabolic-cylinder optical rogue waves in certain inhomogeneous media. An analytical rogue wave solution of the generalized nonlinear Schrödinger equation with spatially modulated coefficients and an external potential in the form of modulated quadratic potential is obtained by the similarity transformation. Numerical simulations are performed for comparison with the analytical solutions and to confirm the stability of the rogue wave solution obtained. These optical rogue waves are built by the products of parabolic-cylinder functions and the basic rogue wave solution of the standard nonlinear Schrödinger equation. Such rogue waves may appear in different forms, as the hump and paw profiles.

  11. Steady viscous flows in an annulus between two cylinders produced by vibrations of the inner cylinder

    CERN Document Server

    Ilin, K

    2010-01-01

    We study the steady streaming between two infinitely long circular cylinders produced by small amplitude transverse vibrations of the inner cylinder about the axis of the outer cylinder. The Vishik-Lyusternik method is employed to construct an asymptotic expansion of the solution of the Navier-Stokes equations in the limit of high-frequency vibrations for Reynolds numbers of order of unity. The effect of the Stokes drift of fluid particles is also studied. It is shown that it is nonzero not only within the boundary layers but also in higher order terms of the expansion of the averaged outer flow.

  12. Design and testing of piezo motors for non-magnetic and/or fine positioning applications

    Science.gov (United States)

    Six, M. F.; Le Letty, R.; Seiler, R.; Coste, P.

    2005-07-01

    Piezoelectric motors offer several outstanding characteristics that may be very interesting for new scientific instruments in space applications. Piezo motors use a combination of electro-mechanical and frictional forces for generating a progressive motion; they are well suited for positioning applications because they exhibit a large force at rest without any power supply, and they often do not require any reduction gear. They are increasingly used in optical applications. Using piezo motors in space applications may become more and more relevant because of the continuous trend towards adaptive optics in future scientific payloads. In general, piezoelectric actuators are more and more used in space. Piezoelectric motors exhibit a number of advantages compared to conventional electromagnetic (stepping) motors, e.g. superior force/mass ratio, improved direct drive capability, no power supply to maintain a position, feasibility of a fully non-magnetic motor design. In this context, two complementary concepts have been designed and evaluated in the frame of ESA funded research and development activities: a resonant concept, called Rotary Piezo Actuator (RPA), a quasi-static concept, called Rotary Piezo Motor for High Precision Pointing (RPMHPP). The developed Rotary Piezo Actuator (RPA) is based on a Ultrasonic Piezo Drive (UPD) unit that drives a friction ring on the rotor part supported by a ball bearing assembly. This new motorization principle offers excellent motion dynamics and positioning accuracy combined with a high un-powered torque at standstill, and it does not rely on any magnetic features. A rotary piezo motor compliant with the requirements of a reference space application has been designed and tested. The technology remains challenging to be mastered, since the interdisciplinary aspects of the concept include, among others, drive electronics and controller design, piezo-electricity, contact mechanics and tribology. The conceptual design has lead to a

  13. Effect of stellar wind induced magnetic fields on planetary obstacles of non-magnetized hot Jupiters

    Science.gov (United States)

    Erkaev, N. V.; Odert, P.; Lammer, H.; Kislyakova, K. G.; Fossati, L.; Mezentsev, A. V.; Johnstone, C. P.; Kubyshkina, D. I.; Shaikhislamov, I. F.; Khodachenko, M. L.

    2017-10-01

    We investigate the interaction between the magnetized stellar wind plasma and the partially ionized hydrodynamic hydrogen outflow from the escaping upper atmosphere of non-magnetized or weakly magnetized hot Jupiters. We use the well-studied hot Jupiter HD 209458b as an example for similar exoplanets, assuming a negligible intrinsic magnetic moment. For this planet, the stellar wind plasma interaction forms an obstacle in the planet's upper atmosphere, in which the position of the magnetopause is determined by the condition of pressure balance between the stellar wind and the expanded atmosphere, heated by the stellar extreme ultraviolet radiation. We show that the neutral atmospheric atoms penetrate into the region dominated by the stellar wind, where they are ionized by photoionization and charge exchange, and then mixed with the stellar wind flow. Using a 3D magnetohydrodynamic (MHD) model, we show that an induced magnetic field forms in front of the planetary obstacle, which appears to be much stronger compared to those produced by the solar wind interaction with Venus and Mars. Depending on the stellar wind parameters, because of the induced magnetic field, the planetary obstacle can move up to ≈0.5-1 planetary radii closer to the planet. Finally, we discuss how estimations of the intrinsic magnetic moment of hot Jupiters can be inferred by coupling hydrodynamic upper planetary atmosphere and MHD stellar wind interaction models together with UV observations. In particular, we find that HD 209458b should likely have an intrinsic magnetic moment of 10-20 per cent that of Jupiter.

  14. A scuba diving direct sediment sampling methodology on benthic transects in glacial lakes: procedure description, safety measures, and tests results.

    Science.gov (United States)

    Pardo, Alfonso

    2014-11-01

    This work presents an in situ sediment sampling method on benthic transects, specifically intended for scientific scuba diver teams. It was originally designed and developed to sample benthic surface and subsurface sediments and subaqueous soils in glacial lakes up to a maximum depth of 25 m. Tests were conducted on the Sabocos and Baños tarns (i.e., cirque glacial lakes) in the Spanish Pyrenees. Two 100 m transects, ranging from 24.5 to 0 m of depth in Sabocos and 14 m to 0 m deep in Baños, were conducted. In each test, 10 sediment samples of 1 kg each were successfully collected and transported to the surface. This sampling method proved operative even in low visibility conditions (sampling tests were conducted in Sabocos and Truchas tarns. This sampling methodology can be easily adapted to accomplish underwater sampling campaigns in nonglacial lakes and other continental water or marine environments.

  15. Flow mediated interactions between two cylinders at finite Re numbers

    Science.gov (United States)

    Gazzola, Mattia; Mimeau, Chloe; Tchieu, Andrew A.; Koumoutsakos, Petros

    2012-04-01

    We present simulations of two interacting moving cylinders immersed in a two-dimensional incompressible, viscous flow. Simulations are performed by coupling a wavelet-adapted, remeshed vortex method with the Brinkman penalization and projection approach. This method is validated on benchmark problems and applied to simulations of a master-slave pair of cylinders. The master cylinder's motion is imposed and the slave cylinder is let free to respond to the flow. We study the relative role of viscous and inertia effects in the cylinders interactions and identify related sharp transitions in the response of the slave. The observed differences in the behavior of cylinders with respect to corresponding potential flow simulations are discussed. In addition, it is observed that in certain situations the finite size of the slave cylinders enhances the transport so that the cylinders are advected more effectively than passive tracers placed, respectively, at the same starting position.

  16. The ideal dimensions of a Halbach cylinder of finite length

    CERN Document Server

    Bjørk, R

    2014-01-01

    In this paper the smallest or optimal dimensions of a Halbach cylinder of a finite length for a given sample volume and desired flux density are determined using numerical modeling and parameter variation. A sample volume that is centered in and shaped as the Halbach cylinder bore but with a possible shorter length is considered. The external radius and the length of the Halbach cylinder with the smallest possible dimensions are found as a function of a desired internal radius, length of the sample volume and mean flux density. It is shown that the optimal ratio between the outer and inner radius of the Halbach cylinder does not depend on the length of the sample volume. Finally, the efficiency of a finite length Halbach cylinder is considered and compared with the case of a cylinder of infinite length. The most efficient dimensions for a Halbach cylinder are found and it is shown that the efficiency increases slowly with the length of the cylinder.

  17. Breached cylinder incident at the Portsmouth gaseous diffusion plant

    Energy Technology Data Exchange (ETDEWEB)

    Boelens, R.A. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    On June 16, 1990, during an inspection of valves on partially depleted product storage cylinders, a 14-ton partially depleted product cylinder was discovered breached. The cylinder had been placed in long-term storage in 1977 on the top row of Portsmouth`s (two rows high) storage area. The breach was observed when an inspector noticed a pile of green material along side of the cylinder. The breach was estimated to be approximately 8- inches wide and 16-inches long, and ran under the first stiffening ring of the cylinder. During the continuing inspection of the storage area, a second 14-ton product cylinder was discovered breached. This cylinder was stacked on the bottom row in the storage area in 1986. This breach was also located adjacent to a stiffening ring. This paper will discuss the contributing factors of the breaching of the cylinders, the immediate response, subsequent actions in support of the investigation, and corrective actions.

  18. The JCMT Gould Belt Survey: the effect of molecular contamination in SCUBA-2 observations of Orion A

    Science.gov (United States)

    Coudé, S.; Bastien, P.; Kirk, H.; Johnstone, D.; Drabek-Maunder, E.; Graves, S.; Hatchell, J.; Chapin, E. L.; Gibb, A. G.; Matthews, B.; JCMT Gould Belt Survey Team

    2016-04-01

    Thermal emission from cold dust grains in giant molecular clouds can be used to probe the physical properties, such as density, temperature and emissivity in star-forming regions. We present the Submillimetre Common-User Bolometer Array (SCUBA-2) shared-risk observations at 450 and 850 μm of the Orion A molecular cloud complex taken at the James Clerk Maxwell Telescope (JCMT). Previous studies showed that molecular emission lines can contribute significantly to the measured fluxes in those continuum bands. We use the Heterodyne Array Receiver Programme 12CO J = 3-2 integrated intensity map for Orion A in order to evaluate the molecular line contamination and its effects on the SCUBA-2 maps. With the corrected fluxes, we have obtained a new spectral index α map for the thermal emission of dust in the well-known integral-shaped filament. Furthermore, we compare a sample of 33 sources, selected over the Orion A molecular cloud complex for their high 12CO J = 3-2 line contamination, to 27 previously identified clumps in OMC 4. This allows us to quantify the effect of line contamination on the ratio of 850-450 μm flux densities and how it modifies the deduced spectral index of emissivity β for the dust grains. We also show that at least one Spitzer-identified protostellar core in OMC 5 has a 12CO J = 3-2 contamination level of 16 per cent. Furthermore, we find the strongest contamination level (44 per cent) towards a young star with disc near OMC 2. This work is part of the JCMT Gould Belt Legacy Survey.

  19. The JCMT Gould Belt Survey: A First Look at SCUBA-2 Observations of the Lupus I Molecular Cloud

    Science.gov (United States)

    Mowat, C.; Hatchell, J.; Rumble, D.; Kirk, H.; Buckle, J.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Jenness, T.; Johnstone, D.; Mottram, J. C.; Pattle, K.; Tisi, S.; Francesco, J. Di; Hogerheijde, M. R.; Ward-Thompson, D.; Bastien, P.; Bresnahan, D.; Butner, H.; Chen, M.; Chrysostomou, A.; Coudé, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fich, M.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Rawlings, J.; Retter, B.; Richer, J.; Robertson, D.; Rosolowsky, E.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wouterloot, J.; Yates, J.; Zhu, M.

    2017-01-01

    This paper presents observations of the Lupus I molecular cloud at 450 and 850 µm with SCUBA-2 as part of the James Clerk Maxwell Telescope Gould Belt Survey (JCMT GBS). Nine compact sources, assumed to be the disks of young stellar objects (YSOs), twelve extended protostellar, pre-stellar and starless cores, and one isolated, low luminosity protostar, are detected in the region. Spectral Energy Distributions (SEDs), including submillimetre fluxes, are produced for 15 YSOs, and each is fitted with the models of Robitaille et al. (2006). The proportion of Class 0 / I protostars is higher than that seen in other Gould Belt regions such as Ophiuchus and Serpens. Circumstellar disk masses are calculated for more evolved sources, while protostellar envelope masses are calculated for protostars. Up to four Very Low Luminosity Objects are found, a large fraction when compared to other Spitzer c2d regions. One YSO has a disk mass greater than the minimum mass solar nebula (MMSN). Twelve starless / protostellar cores are detected by SCUBA-2, and their masses are calculated. The stability of these cores is examined using both the thermal Jeans mass and a turbulent virial mass when possible. Two cores in Lupus I are super-Jeans and contain no known YSOs. One of these cores has a virial parameter of 1.1 ± 0.4, and could therefore be prestellar. The high ratio of Class 0 / I to Class III YSOs (1:1), and the presence of a prestellar core candidate, provides support for the hypothesis that a shock recently triggered star formation in Lupus I.

  20. The JCMT Gould Belt Survey: A First Look at SCUBA-2 Observations of the Lupus I Molecular Cloud

    Science.gov (United States)

    Mowat, C.; Hatchell, J.; Rumble, D.; Kirk, H.; Buckle, J.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Jenness, T.; Johnstone, D.; Mottram, J. C.; Pattle, K.; Tisi, S.; Di Francesco, J.; Hogerheijde, M. R.; Ward-Thompson, D.; Bastien, P.; Bresnahan, D.; Butner, H.; Chen, M.; Chrysostomou, A.; Coudé, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fich, M.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Rawlings, J.; Retter, B.; Richer, J.; Robertson, D.; Rosolowsky, E.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wouterloot, J.; Yates, J.; Zhu, M.

    2017-05-01

    This paper presents observations of the Lupus I molecular cloud at 450 and 850 μm with Submillimetre Common User Bolometer Array (SCUBA-2) as part of the James Clerk Maxwell Telescope Gould Belt Survey (JCMT GBS). Nine compact sources, assumed to be the discs of young stellar objects (YSOs), 12 extended protostellar, pre-stellar and starless cores, and one isolated, low-luminosity protostar, are detected in the region. Spectral energy distributions, including submillimetre fluxes, are produced for 15 YSOs, and each is fitted with the models of Robitaille et al. The proportion of Class 0/I protostars is higher than that seen in other Gould Belt regions such as Ophiuchus and Serpens. Circumstellar disc masses are calculated for more evolved sources, while protostellar envelope masses are calculated for protostars. Up to four very low luminosity objects are found; a large fraction when compared to other Spitzer c2d regions. One YSO has a disc mass greater than the minimum mass solar nebula. 12 starless/protostellar cores are detected by SCUBA-2 and their masses are calculated. The stability of these cores is examined using both the thermal Jeans mass and a turbulent virial mass when possible. Two cores in Lupus I are super-Jeans and contain no known YSOs. One of these cores has a virial parameter of 1.1 ± 0.4, and could therefore be pre-stellar. The high ratio of Class 0/I to Class III YSOs (1:1), and the presence of a pre-stellar core candidate, provides support for the hypothesis that a shock recently triggered star formation in Lupus I.

  1. Drag Coefficient of Thin Flexible Cylinder

    Science.gov (United States)

    Subramanian, Chelakara; Gurram, Harika

    2015-11-01

    Measurements of drag coefficients of thin flexible cylindrical wires are described for the Reynolds number range between 250 - 1000. Results indicate that the coefficient values are about 20 to 30 percent lower than the reported laminar flow values for rigid cylinders. Possible fluid dynamics mechanism causing the reduction in drag will be discussed.

  2. Frequency spectra of laminated piezoelectric cylinders

    Science.gov (United States)

    Siao, J. C.-T.; Dong, S. B.; Song, J.

    1994-07-01

    A finite-element method is presented for determining the vibrational characteristics of a circular cylinder composed of bonded piezoelectric layers. Finite-element modeling occurs in the radial direction only using quadratic polynomials and the variationally derived partial differential equations are functions of the hoop and axial coordinates (theta, z) and time t. Using solution form Q exp (i(xi(z) + n(theta) + (omega)t)), with Q as the nodal amplitudes, leads to an algebraic eigensystem where any one of the three parameters (n, xi, omega), the circumferential or axial wave number or natural frequency, can act as the eigenvalue. Integer values always are assigned to n, leaving two possible eigenvalue problems. With omega as the eigenvalue and real values assigned to xi, the solutions represent propagating waves or harmonic standing vibrations in an infinite cylinder. When xi is the eigenvalue and real values assigned to omega, this eigensystem admits both real and complex eigendata. Real xi's represent propagating waves or harmonic standing vibrations as noted before. Complex conjugate pairs of xi 's describe end vibrations, which arise when an incident wave impinges upon a free end of a cylindrical bar. They are standing waves whose amplitudes decay sinusoidally or exponentially from the free end into the interior. Two examples are given to illustrate the method of analysis, viz., a solid piezoelectric cylinder of PZT-4 ceramic material and a two-layer cylinder of PZT-4 covering an isotropic material.

  3. In-Cylinder Heat Transfer Modelling

    Directory of Open Access Journals (Sweden)

    Žák Zdeněk

    2016-12-01

    Full Text Available The goal of the paper is to discuss specific features of the in-cylinder heat transfer calculation based on widely used empirical formulas. The potential of in-house codes compared with commercially available software packages is presented. The principles of user models in the GT-SUITE environment are also explained. The results of calibrated models are briefly discussed.

  4. Acoustic signal analysis of underwater elastic cylinder

    Institute of Scientific and Technical Information of China (English)

    LI Xiukun; YANG Shi'e

    2001-01-01

    The echoes of underwater elastic cylinder comprise two types of acoustic components: Geometrical scattering waves and elastic scattering waves. The transfer function is appropriate to characterize the echo of targets. And the discrete wavelet transform of amplitude spectrum is presented and used to identify the resonant components of underwater targets.PACS numbers: 43.30, 43.60

  5. The Experience Cylinder, an immersive interactive platform

    DEFF Research Database (Denmark)

    Andreasen, Troels; Gallagher, John Patrick; Møbius, Nikolaj

    2011-01-01

    This paper describes the development of an experimental interactive installation, a so-called "experience cylinder", intended as a travelogue and developed specifically to provide a narrative about the Viking ship Sea Stallion’s (Havhingst) voyage from Roskilde to Dublin and back. The installatio...

  6. Spin-Up in a Rectangular Cylinder

    Science.gov (United States)

    1993-12-01

    cylinder by scaling as follows: I I IElt , and p = E’,X, 3.22 where we have scaled the radial and vertical flow to be higher order in Ekman number than the...two flow visualization systems, and the rectangular tank with prepared water. Fig- ure 4.1 is a schematic of this system, which we describe below.I I

  7. Inner and outer cylinders of the CMS vacuum tank.

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    The vacuum tank of the CMS magnet system consists of inner and outer stainless-steel cylinders and houses the superconducting coil. The inner cylinder contains all the barrel sub-detectors, which it supports via a system of horizontal rails. The cylinder is pictured here in the vertical position on a yellow platform mounted on the ferris-wheel support structure. This will allow it to be pivoted and inserted into the already installed outer cylinder, through which this photo was taken.

  8. Dependence of the magnetization on the interface morphology in ultra-thin magnetic/non-magnetic films: Monte Carlo approach

    Energy Technology Data Exchange (ETDEWEB)

    Razouk, A. [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco); Sahlaoui, M., E-mail: msahlaoui@yahoo.fr [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco); Sajieddine, M. [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco)

    2009-07-30

    Using Monte Carlo simulations, we have studied the dependence of magnetic properties on interface morphology in magnetic/non-magnetic (M/NM) multilayers. Our aim is to relate macroscopic magnetic properties of the multilayers to their concentration profile at the interface. Our model consists of an alternate staking of magnetic and non-magnetic layers with disordered interfaces. We have considered different concentration and the existence of local magnetic domains at the interface. The results indicate the crucial dependence of magnetization amplitude with interface multilayers atomic composition and the spatial arrangement of magnetic atoms. In particular, we show that isolated islands at the interface leads to the apparition of super-paramagnetic behavior.

  9. Design of Matched Zero-Index Metamaterials Using Non-Magnetic Inclusions in Epsilon-Near-Zero (ENZ) Media

    OpenAIRE

    Silveirinha, Mario; Engheta, Nader

    2006-01-01

    In this work, we study the electrodynamics of metamaterials that consist of resonant non-magnetic inclusions embedded in an epsilon-near-zero (ENZ) host medium. It is shown that the inclusions can be designed in such a way that both the effective permittivity and permeability of the composite structure are simultaneously zero. Two different metamaterial configurations are studied and analyzed in detail. For a particular class of problems, it is analytically proven that such matched zero-index...

  10. AN INVESTIGATION ON SOFT MAGNETIC AND NON-MAGNETIC MATERIALS UNDER LOW FREQUENCY FOR BIOMEDICAL SENSOR APPLICATION

    Directory of Open Access Journals (Sweden)

    Sheroz Khan

    2012-02-01

    Full Text Available In consequence of the recent development of magnetic sensors in biomedical sector, the investigation of magneticmaterials has been a contributing factor in application stage. This paper proposes a novel technique to investigate materials by obtaining unique distinctive impedance peaks with unique impedance values. A magneto-inductive sensoris used to measure the induction of magnetic and non-magnetic impedance peaks related to the change in permeability, thus characterizing the materials under low frequency.

  11. INDUCTION HEATING OF NON-MAGNETIC SHEET METALS IN THE FIELD OF A FLAT CIRCULAR MULTITURN SOLENOID

    Directory of Open Access Journals (Sweden)

    Y. Batygin

    2016-06-01

    Full Text Available The theoretical analysis of electromagnetic processes in the system for induction heating presented by a flat circular multiturn solenoid positioned above a plane of thin sheet non-magnetic metal has been conducted. The calculated dependences for the current induced in a metal sheet blank and ratio of transformation determined have been obtained. The maximal value of the transformation ratio with regard to spreading the eddy-currents over the whole area of the sheet metal has been determined.

  12. 49 CFR 173.316 - Cryogenic liquids in cylinders.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Cryogenic liquids in cylinders. 173.316 Section... REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.316 Cryogenic liquids in cylinders. (a) General requirements. (1) A cylinder may not be loaded with a cryogenic liquid colder than...

  13. Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders

    NARCIS (Netherlands)

    De Kanter, J.L.C.G.

    2006-01-01

    Summary accompanying the thesis: Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders by Jens de Kanter This thesis presents the investigation of the crush behaviour of both monolithic aluminium cylinders and externally fibre reinforced aluminium cylinders. The research is based

  14. Electromagnetic Wave Scattering By the Coated Impedance Cylinder

    Directory of Open Access Journals (Sweden)

    V.I. Vyunnik

    2010-01-01

    Full Text Available In this work the boundary conditions for the impedance circular cylinder coated by a low contrast dielectric thin layer are derived. Expression for the reduced impedance of the cylinder is obtained. Conditions and applicability limits of the proposed approach are defined. Influence of the coating impedance on the reduced impedance of the cylinder is investigated.

  15. Turbulent Taylor–Couette flow with stationary inner cylinder

    NARCIS (Netherlands)

    Ostilla-Monico, R.; Verzicco, Roberto; Lohse, Detlef

    2016-01-01

    A series of direct numerical simulations were performed of Taylor–Couette (TC) flow, the flow between two coaxial cylinders, with the outer cylinder rotating and the inner one fixed. Three cases were considered, where the Reynolds number of the outer cylinder was $Re_{o}=5.5\\times 10^{4}$Reo=5.5×104

  16. Investigation of breached depleted UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    DeVan, J.H. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States)

    1991-12-31

    In June 1990, during a three-site inspection of cylinders being used for long-term storage of solid depleted UF{sub 6}, two 14-ton cylinders at Portsmouth, Ohio, were discovered with holes in the barrel section of the cylinders. An investigation team was immediately formed to determine the cause of the failures and their impact on future storage procedures and to recommend corrective actions. Subsequent investigation showed that the failures most probably resulted from mechanical damage that occurred at the time that the cylinders had been placed in the storage yard. In both cylinders evidence pointed to the impact of a lifting lug of an adjacent cylinder near the front stiffening ring, where deflection of the cylinder could occur only by tearing the cylinder. The impacts appear to have punctured the cylinders and thereby set up corrosion processes that greatly extended the openings in the wall and obliterated the original crack. Fortunately, the reaction products formed by this process were relatively protective and prevented any large-scale loss of uranium. The main factors that precipitated the failures were inadequate spacing between cylinders and deviations in the orientations of lifting lugs from their intended horizontal position. After reviewing the causes and effects of the failures, the team`s principal recommendation for remedial action concerned improved cylinder handling and inspection procedures. Design modifications and supplementary mechanical tests were also recommended to improve the cylinder containment integrity during the stacking operation.

  17. Sub-wavelength metamaterial cylinders with multiple dipole resonances

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2009-01-01

    It has been shown that the sub-wavelength resonances of the individual MTM cylinders also occur for electrically small configurations combining 2 or 4 cylinders. For the 2-and 4-cylinder configurations the overall size is 1/20 and 1/12.5 of the smallest wavelength, respectively. These MTM...... configuration thus offer the possibility for multi-resonant electrically small configurations....

  18. Controlling a negative loaded hydraulic cylinder using pressure feedback

    DEFF Research Database (Denmark)

    Hansen, M.R.; Andersen, T.O.

    2010-01-01

    showing that without extra measures such a system will be unstable in a substantial part of the cylinder stroke. The stability criterion is expressed in hard quantities: Cylinder volumes, cylinder area ratio and overcenter valve pilot area ratio. A pressure feed back scheme that has as target to maintain...

  19. Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders

    NARCIS (Netherlands)

    De Kanter, J.L.C.G.

    2006-01-01

    Summary accompanying the thesis: Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders by Jens de Kanter This thesis presents the investigation of the crush behaviour of both monolithic aluminium cylinders and externally fibre reinforced aluminium cylinders. The research is based

  20. Turbulent Taylor–Couette flow with stationary inner cylinder

    NARCIS (Netherlands)

    Ostilla-Monico, R.; Verzicco, R.; Lohse, D.

    2016-01-01

    A series of direct numerical simulations were performed of Taylor–Couette (TC) flow, the flow between two coaxial cylinders, with the outer cylinder rotating and the inner one fixed. Three cases were considered, where the Reynolds number of the outer cylinder was $Re_{o}=5.5\\times 10^{4}$Reo=5.5×104

  1. The ideal dimensions of a Halbach cylinder of finite length

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2011-01-01

    but with a possible shorter length is considered. The external radius and the length of the Halbach cylinder with the smallest possible dimensions are found as a function of a desired internal radius, length of the sample volume and mean flux density. It is shown that the optimal ratio between the outer and inner...... radius of the Halbach cylinder does not depend on the length of the sample volume. Finally, the efficiency of a finite length Halbach cylinder is considered and compared with the case of a cylinder of infinite length. The most efficient dimensions for a Halbach cylinder are found and it is shown...

  2. Performance of Air-cooled Engine Cylinders Using Blower Cooling

    Science.gov (United States)

    Schey, Oscar W; Ellerbrock, Herman H , Jr

    1936-01-01

    An investigation was made to obtain information on the minimum quantity of air and power required to cool conventional air cooled cylinders at various operating conditions when using a blower. The results of these tests show that the minimum power required for satisfactory cooling with an overall blower efficiency of 100 percent varied from 2 to 6 percent of the engine power depending on the operating conditions. The shape of the jacket had a large effect on the cylinder temperatures. Increasing the air speed over the front of the cylinder by keeping the greater part of the circumference of the cylinder covered by the jacket reduced the temperatures over the entire cylinder.

  3. Using underwater cameras to assess the effects of snorkeler and SCUBA diver presence on coral reef fish abundance, family richness, and species composition.

    Science.gov (United States)

    Dearden, P; Theberge, M; Yasué, M

    2010-04-01

    The results of underwater visual fish censuses (UVC) could be affected by fish changing their behavior in response to the snorkeler or diver conducting the survey. We used an underwater video camera to assess how fish abundance, family richness, and community composition were affected by the presence of snorkelers (n = 12) and self-contained underwater breathing apparatus (SCUBA) divers (n = 6) on a coral reef in Thailand. The total number of families, abundance of some fish families, and overall species composition showed significant differences before and during snorkeling disturbances. We did not detect significant and consistent changes to these parameters in the presence of a SCUBA diver; however, this could be a result of lower statistical power. We suggest that the use of a stationary video camera may help cross-check data that is collected through UVC to assess the true family composition and document the presence of rare and easily disturbed species.

  4. Radiation levels on empty cylinders containing heel material

    Energy Technology Data Exchange (ETDEWEB)

    Shockley, C.W. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Empty UF{sub 6} cylinders containing heel material were found to emit radiation levels in excess of 200 mr/hr, the maximum amount stated in ORO-651. The radiation levels were as high as 335 mr/hr for thick wall (48X and 48Y) cylinders and 1050 mr/hr for thin wall (48G and 48H) cylinders. The high readings were found only on the bottom of the cylinders. These radiation levels exceeded the maximum levels established in DOT 49 CFR, Part 173.441 for shipment of cylinders. Holding periods of four weeks for thick-wall cylinders and ten weeks for thin-wall cylinders were established to allow the radiation levels to decay prior to shipment.

  5. Evaluation of Concrete Cylinder Tests Using Finite Elements

    DEFF Research Database (Denmark)

    Saabye Ottosen, Niels

    1984-01-01

    Nonlinear axisymmetric finite element analyses are performed on the uniaxial compressive test of concrete cylinders. The models include thick steel loading plates, and cylinders with height‐to‐diameter ratios (h/d) ranging from 1‐3 are treated. A simple constitutive model of the concrete...... is employed, which accounts for the strain hardening and softening in the pre‐ and postfailure regions, respectively. When h/d  =  2, the failure mode is found to consist of undisturbed end cones and the occurrence of strain softening, especially in the outer region of the cylinder middle. For shorter...... cylinders the strain softening is more pronounced along the surface of the cylinder middle, whereas longer cylinders exhibit a more uniform distribution of strain softening. The failure modes for force and displacement controlled tests are found to be similar. If long cylinders are to provide the true...

  6. Features of Flow Past Square Cylinder with a Perforated Plate

    Institute of Scientific and Technical Information of China (English)

    汪健生; 徐亚坤; 程浩杰

    2016-01-01

    A numerical investigation was performed on the reduction of the fluid forces acting on the square cylin-der in the laminar flow regime with a perforated plate. The effects of geometric parameters such as the distance between the square cylinder and the perforated plate on the wake of the square cylinder were discussed. Further-more, the flow characteristics such as the drag coefficient, lift coefficient, Strouhal number and flow pattern were obtained. It can be concluded that the drag force of the square cylinder reduces to some extent due to the addition of the perforated plate. The flow structure varies when the perforated plate is located behind the square cylinder. Moreover, the recirculation zone augments with the increase ofL/D, and the vortex trace on the upper and lower surface of the square cylinder moves gradually backwards until a stable recirculation zone formed between the square cylinder and the perforated plate.

  7. Upgraded Analytical Model of the Cylinder Test

    Energy Technology Data Exchange (ETDEWEB)

    Souers, P. Clark; Lauderbach, Lisa; Garza, Raul; Ferranti, Louis; Vitello, Peter

    2013-03-15

    A Gurney-type equation was previously corrected for wall thinning and angle of tilt, and now we have added shock wave attenuation in the copper wall and air gap energy loss. Extensive calculations were undertaken to calibrate the two new energy loss mechanisms across all explosives. The corrected Gurney equation is recommended for cylinder use over the original 1943 form. The effect of these corrections is to add more energy to the adiabat values from a relative volume of 2 to 7, with low energy explosives having the largest correction. The data was pushed up to a relative volume of about 15 and the JWL parameter ω was obtained directly. The total detonation energy density was locked to the v=7 adiabat energy density, so that the Cylinder test gives all necessary values needed to make a JWL.

  8. Locomotion gaits of a rotating cylinder pair

    Science.gov (United States)

    van Rees, Wim M.; Novati, Guido; Koumoutsakos, Petros; Mahadevan, L.

    2015-11-01

    Using 2D numerical simulations of the Navier-Stokes equations, we demonstrate that a simple pair of rotating cylinders can display a range of locomotion patterns of biological and engineering interest. Steadily counter-rotating the cylinders causes the pair to move akin to a vortex dipole for low rotation rates, but as the rotational velocity is increased the direction of motion reverses. Unsteady rotations lead to different locomotion gaits that resemble jellyfish (for in-phase rotations) and undulating swimmers (for out-of-phase rotations). The small number of parameters for this simple system allows us to systematically map the phase space of these gaits, and allows us to understand the underlying physical mechanisms using a minimal model with implications for biological locomotion and engineered analogs.

  9. Intergalactic Filaments as Isothermal Gas Cylinders

    CERN Document Server

    Harford, A Gayler

    2010-01-01

    Using a cosmological simulation at redshift 5, we find that the baryon-rich cores of intergalactic filaments radiating from galaxies commonly form isothermal gas cylinders. The central gas density is typically about 500 times the cosmic mean total density, and the temperature is typically 1-2 times 10^4 K, just above the Lyman alpha cooling floor. These findings argue that the hydrodynamic properties of the gas are more important than the dark matter in determining the structure. Filaments form a major pipeline for the transport of gas into the centers of galaxies. Since the temperature and ionization state of the gas completely determine the mass per unit length of an isothermal gas cylinder, our findings suggest a constraint upon gas transport into galaxies by this mechanism.

  10. Anomalous magnetoresistance in magnetized topological insulator cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Siu, Zhuo Bin, E-mail: a0018876@nus.edu.sg [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore); Data Storage Institute, Agency for Science, Technology and Research, Singapore 117608 (Singapore); Jalil, Mansoor B. A. [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore)

    2015-05-07

    The close coupling between the spin and momentum degrees of freedom in topological insulators (TIs) presents the opportunity for the control of one to manipulate the other. The momentum can, for example, be confined on a curved surface and the spin influenced by applying a magnetic field. In this work, we study the surface states of a cylindrical TI magnetized in the x direction perpendicular to the cylindrical axis lying along the z direction. We show that a large magnetization leads to an upwards bending of the energy bands at small |k{sub z}|. The bending leads to an anomalous magnetoresistance where the transmission between two cylinders magnetized in opposite directions is higher than when the cylinders are magnetized at intermediate angles with respect to each other.

  11. Upgraded Analytical Model of the Cylinder Test

    Energy Technology Data Exchange (ETDEWEB)

    Souers, P. Clark [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center; Lauderbach, Lisa [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center; Garza, Raul [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center; Ferranti, Louis [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center; Vitello, Peter [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center

    2013-03-15

    A Gurney-type equation was previously corrected for wall thinning and angle of tilt, and now we have added shock wave attenuation in the copper wall and air gap energy loss. Extensive calculations were undertaken to calibrate the two new energy loss mechanisms across all explosives. The corrected Gurney equation is recommended for cylinder use over the original 1943 form. The effect of these corrections is to add more energy to the adiabat values from a relative volume of 2 to 7, with low energy explosives having the largest correction. The data was pushed up to a relative volume of about 15 and the JWL parameter ω was obtained directly. Finally, the total detonation energy density was locked to the v = 7 adiabat energy density, so that the Cylinder test gives all necessary values needed to make a JWL.

  12. Do reef fish habituate to diver presence? Evidence from two reef sites with contrasting historical levels of SCUBA intensity in the Bay Islands, Honduras.

    Science.gov (United States)

    Titus, Benjamin M; Daly, Marymegan; Exton, Dan A

    2015-01-01

    Contact between humans and the marine environment is increasing, but the capacity of communities to adapt to human presence remains largely unknown. The popularization of SCUBA diving has added a new dimension to human impacts in aquatic systems and, although individual-level impacts have been identified, cumulative effects on ecosystem function and community-wide responses are unclear. In principle, habituation may mitigate the consequences of human presence on the biology of an individual and allow the quick resumption of its ecological roles, but this has not been documented in aquatic systems. Here, we investigate the short-term impact of human presence and the long-term habituation potential of reef-fish communities to recreational SCUBA divers by studying symbiotic cleaning interactions on coral reefs with differing levels of historical contact with divers. We show that incidences of human contact result in a smaller decline in ecosystem function and more rapid resumption of baseline services on a reef in Utila, Honduras that has heavy historical levels of SCUBA diver presence, compared to an un-dived reef site in the Cayos Cochinos Marine Protected Area (CCMPA). Nonetheless, despite the generally smaller change in ecosystem function and decades of regular contact with divers, cleaning behavior is suppressed by >50% at Utila when divers are present. We hypothesize that community-wide habituation of reef fish is not fully achievable and may be biologically restricted to only partial habituation. Differential responses to human presence impacts the interpretation and execution of behavioral research where SCUBA is the predominant means of data collection, and provides an important rationale for future research investigating the interplay between human presence, ecosystem function, and community structure on coral reefs.

  13. Parabolic cylinder functions of large order

    Science.gov (United States)

    Jones, D. S.

    2006-06-01

    The asymptotic behaviour of parabolic cylinder functions of large real order is considered. Various expansions in terms of elementary functions are derived. They hold uniformly for the variable in appropriate parts of the complex plane. Some of the expansions are doubly asymptotic with respect to the order and the complex variable which is an advantage for computational purposes. Error bounds are determined for the truncated versions of the asymptotic series.

  14. Four-Cylinder Stirling Engine Control Simulation

    Science.gov (United States)

    Daniele, C. J.; Lorenzo, C. F.

    1986-01-01

    Four-cylinder, Stirling-engine, transient-engine-simulation computer program developed. Program intended for control analysis. Associated engine model simplified to shorten computer calculation time. Model includes engine mechanical-drive dynamics and vehicle-load effects. Computer program also includes subroutines that allow acceleration of engine by addition of hydrogen to system and braking of engine by short circuiting of working spaces.

  15. The JCMT Gould Belt Survey: First results from the SCUBA-2 observations of the Ophiuchus molecular cloud and a virial analysis of its prestellar core population

    CERN Document Server

    Pattle, K; Kirk, J M; White, G J; Drabek-Maunder, E; Buckle, J; Beaulieu, S F; Berry, D S; Broekhoven-Fiene, H; Currie, M J; Fich, M; Hatchell, J; Kirk, H; Jenness, T; Johnstone, D; Mottram, J C; Nutter, D; Pineda, J E; Quinn, C; Salji, C; Tisi, S; Walker-Smith, S; Di Francesco, J; Hogerheijde, M R; André, Ph; Bastien, P; Bresnahan, D; Butner, H; Chen, M; Chrysostomou, A; Coude, S; Davis, C J; Duarte-Cabral, A; Fiege, J; Friberg, P; Friesen, R; Fuller, G A; Graves, S; Greaves, J; Gregson, J; Griffin, M J; Holland, W; Joncas, G; Knee, L B G; Könyves, V; Mairs, S; Marsh, K; Matthews, B C; Moriarty-Schieven, G; Rawlings, J; Richer, J; Robertson, D; Rosolowsky, E; Rumble, D; Sadavoy, S; Spinoglio, L; Thomas, H; Tothill, N; Viti, S; Wouterloot, J; Yates, J; Zhu, M

    2015-01-01

    In this paper we present the first observations of the Ophiuchus molecular cloud performed as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) with the SCUBA-2 instrument. We demonstrate methods for combining these data with previous HARP CO, Herschel, and IRAM N$_{2}$H$^{+}$ observations in order to accurately quantify the properties of the SCUBA-2 sources in Ophiuchus. We produce a catalogue of all of the sources found by SCUBA-2. We separate these into protostars and starless cores. We list all of the starless cores and perform a full virial analysis, including external pressure. This is the first time that external pressure has been included in this level of detail. We find that the majority of our cores are either bound or virialised. Gravitational energy and external pressure are on average of a similar order of magnitude, but with some variation from region to region. We find that cores in the Oph A region are gravitationally bound prestellar cores, while cores in the Oph C and ...

  16. Axisymmetric planar cracks in finite hollow cylinders of transversely isotropic material: Part II—cutting method for finite cylinders

    Science.gov (United States)

    Pourseifi, M.; Faal, R. T.; Asadi, E.

    2017-06-01

    This paper is the outcome of a companion part I paper allocated to finite hollow cylinders of transversely isotropic material. The paper provides the solution for the crack tip stress intensity factors of a system of coaxial axisymmetric planar cracks in a transversely isotropic finite hollow cylinder. The lateral surfaces of the hollow cylinder are under two inner and outer self-equilibrating distributed shear loadings. First, the stress fields due to these loadings are given for both infinite and finite cylinders. In the next step, the state of stress in an infinite hollow cylinder with transversely isotropic material containing axisymmetric prismatic and radial dislocations is extracted from part I paper. Next, using the distributed dislocation technique, the mixed mode crack problem in finite cylinder is reduced to Cauchy-type singular integral equations for dislocation densities on the surfaces of the cracks. The problem of a cracked finite hollow cylinder is treated by cutting method; i.e., the infinite cylinder is cut to a finite one by slicing it using two annular axisymmetric cracks at its ends. The cutting method is validated by comparing the state of stress of a sliced intact infinite cylinder with that of an intact finite cylinder. The paper is furnished to several examples to study the effect of crack type and location in finite cylinders on the ensuing stress intensity factors of the cracks and the interaction between the cracks.

  17. MHD boundary layer slip flow and heat transfer of ferrofluid along a stretching cylinder with prescribed heat flux.

    Science.gov (United States)

    Qasim, Muhammad; Khan, Zafar Hayat; Khan, Waqar Ahmad; Ali Shah, Inayat

    2014-01-01

    This study investigates the magnetohydrodynamic (MHD) flow of ferrofluid along a stretching cylinder. The velocity slip and prescribed surface heat flux boundary conditions are employed on the cylinder surface. Water as conventional base fluid containing nanoparticles of magnetite (Fe3O4) is used. Comparison between magnetic (Fe3O4) and non-magnetic (Al2O3) nanoparticles is also made. The governing non-linear partial differential equations are reduced to non-linear ordinary differential equations and then solved numerically using shooting method. Present results are compared with the available data in the limiting cases. The present results are found to be in an excellent agreement. It is observed that with an increase in the magnetic field strength, the percent difference in the heat transfer rate of magnetic nanoparticles with Al2O3 decreases. Surface shear stress and the heat transfer rate at the surface increase as the curvature parameter increases, i.e curvature helps to enhance the heat transfer.

  18. Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites

    Science.gov (United States)

    Hoffman, Douglas C.; Potter, Benjamin

    2013-01-01

    Quality knives are typically fabricated from high-strength steel alloys. Depending on the application, there are different requirements for mechanical and physical properties that cause problems for steel alloys. For example, diver's knives are generally used in salt water, which causes rust in steel knives. Titanium diver's knives are a popular alternative due to their salt water corrosion resistance, but are too soft to maintain a sharp cutting edge. Steel knives are also magnetic, which is undesirable for military applications where the knives are used as a tactical tool for diffusing magnetic mines. Steel is also significantly denser than titanium (8 g/cu cm vs. 4.5 g/cu cm), which results in heavier knives for the same size. Steel is hard and wear-resistant, compared with titanium, and can keep a sharp edge during service. A major drawback of both steel and titanium knives is that they must be ground or machined into the final knife shape from a billet. Since most knives have a mirrored surface and a complex shape, manufacturing them is complex. It would be more desirable if the knife could be cast into a net or near-net shape in a single step. The solution to the deficiencies of titanium, steel, and ceramic knives is to fabricate them using bulk metallic glasses (or composites). These alloys can be cast into net or near-net shaped knives with a combination of properties that exceed both titanium and steel. A commercially viable BMG (bulk metallic glass) or composite knife is one that exhibits one or all of the following properties: It is based on titanium, has a self-sharpening edge, can retain an edge during service, is hard, is non-magnetic, is corrosion-resistant against a variety of corrosive environments, is tough (to allow for prying), can be cast into a net-shape with a mirror finish and a complex shape, has excellent wear resistance, and is low-density. These properties can be achieved in BMG and composites through alloy chemistry and processing. For

  19. Tricritical wetting in the two-dimensional Ising magnet due to the presence of localized non-magnetic impurities.

    Science.gov (United States)

    Trobo, Marta L; Albano, Ezequiel V

    2016-03-31

    Fixed vacancies (non-magnetic impurities) are placed along the centre of Ising strips in order to study the wetting behaviour in this confined system, by means of numerical simulations analysed with the aid of finite size scaling and thermodynamic integration methods. By considering strips of size L × M (L interface between magnetic domains of different orientation (driven by the corresponding surface fields), which are the precursors of the wetting transitions that occur in the thermodynamic limit. By placing vacancies or equivalently non-magnetic impurities along the centre of the sample, we found that for low vacancy densities the wetting transitions are of second order, while by increasing the concentration of vacancies the transitions become of first order. Second- and first-order lines meet in tricritical wetting points (H(tric)(SW), T(tric)(W)), where H(tric)(SW) and T(Tric)(W) are the magnitude of the surface field and the temperature, respectively. In the phase diagram, tricritical points shift from the high temperature and weak surface field regime at large vacancy densities to the T --> 0, H(tric)(SW) --> 1 limit for low vacancy densities. By comparing the locations of the tricritical points with those corresponding to the case of mobile impurities, we conclude that in order to observe similar effects, in the latter the required density of impurities is much smaller (e.g. by a factor 3-5). Furthermore, a proper density of non magnetic impurities placed along the centre of a strip can effectively pin rather flat magnetic interfaces for suitable values of the competing surface fields and temperature.

  20. Dilution Effects on Two-Dimensional Heisenberg Antiferromagnets with Non-Magnetic Spin-Gapped Ground State

    OpenAIRE

    Yasuda, Chitoshi; Todo, Synge; Matsumoto, Munehisa; Takayama, Hajime

    2002-01-01

    Dilution effects on spin-1/2 quantum Heisenberg antiferromagnets with a non-magnetic spin-gapped ground state are studied by means of the qunatum Monte Carlo simulation. In the site-diluted system, an antiferromagnetic long-range order (AF-LRO) is induced at an infinitesimal concentration of dilution due to an effective coupling $\\tilde{J}_{mn}$ between induced magnetic moments. In the bond-diluted case, on the other hand, the AF-LRO is not induced up to a certain concentration of dilution du...

  1. Influence of Non-Magnetic Substitutional Atoms on Spontaneous Moment and Curie Temperature of Ce2Co17 Compounds

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The structure and magnetic properties of Ce2Co17-xMx(M=Ga,Al and Si) compounds for M concentrations up to x=5 were studied by means of X-ray diffraction and magnetic measurements. The experimental results show that the Curie temperatures and Co spontaneous magnetization decrease significantly with increasing the addition of non-magnetic substitutional atoms, and that Si which has a minimum solid solubility in Ce2Co17 causes a largest reduction of Curie temperature, spontaneous magnetization and moment per Co atom compared with Ga and Al.

  2. Differences in scour around a single surface-piercing cylinder and a submerged cylinder

    Science.gov (United States)

    Beninati, M. L.; Volpe, M. A.; Riley, D. R.; Krane, M.

    2011-12-01

    The equilibrium state of scour for a single surface piercing cylinder and a submerged cylinder of specific aspect ratio are presented. The equilibrium state is defined by a scour depth and associated time interval for a given set of flow conditions. Control variables such as sediment coarseness (or grain size) and cylinder size are held constant, while the flow intensity is varied. Sediment bed form topology is characterized with a series of two-dimensional slices across the bed for both the surface-piercing and submerged cylinder cases. Test results will help identify the geometry and pattern of the scour around the cylinders to aid in the optimal design of marine hydrokinetic (MHK) support structures in an effort to help minimize the deleterious impact of these devices on the local substrate. This study is performed in the small-scale testing platform in the hydraulic flume facility (32 ft long, 4 ft wide and 1.25 ft deep) in the Environmental Fluid Mechanics and Hydraulics Laboratory (EFM&H) at Bucknell University. The cylinders, of the same material and diameter, are placed centrally in the sediment filled test section (2.5 ft long, 2 ft wide and 0.75 ft deep) of the platform. Flow field measurements are taken with a 16-MHz Micro Acoustic Doppler Velocimeter while water depth is acquired using an ultrasonic distance sensor. These devices are attached to a gantry system that can be accurately positioned anywhere in the test section. Clear-water conditions (in the absence of live-bed scour) are maintained to study the effect of the horseshoe and wake vortices on the displacement of sediment around the cylinder as well as downstream of the device. Bed form topology is measured using an HR Wallingford 2D Sediment Bed Profiler with a low-powered laser distance sensor to accurately characterize changes in bed form around the cylinders. Additionally, specifications for testing such as operational procedures for start-up and shut-down of the facility are given.

  3. The JCMT Gould Belt Survey: low-mass proto-planetary discs from a SCUBA-2 census of NGC1333

    CERN Document Server

    Dodds, P; Scholz, A; Hatchell, J; Holland, W S

    2014-01-01

    NGC1333 is a 1-2 Myr old cluster of stars in the Perseus molecular cloud. We used 850mu data from the Gould Belt Survey with SCUBA-2 on the JCMT to measure or place limits on disc masses for 82 Class II sources in this cluster. Eight disc-candidates were detected; one is estimated to have mass of about 9 Jupiter masses in dust plus gas, while the others host only 2-4 Jupiter masses of circumstellar material. None of these discs exceeds the threshold for the 'Minimum Mass Solar Nebula' (MMSN). This reinforces previous claims that only a small fraction of Class II sources at an age of 1-2 Myr has discs exceeding the MMSN threshold and thus can form a planetary system like our own. However, other regions with similarly low fractions of MMSN discs (IC348, UpSco, SigmaOri) are thought to be older than NGC1333. Compared with coeval regions, the exceptionally low fraction of massive discs in NGC1333 cannot easily be explained by the effects of UV radiation or stellar encounters. Our results indicate that additional ...

  4. Herschel and SCUBA-2 imaging and spectroscopy of a bright, lensed submillimetre galaxy at z = 2.3

    CERN Document Server

    Ivison, R J; Swinyard, B; Smail, Ian; Pearson, C P; Rigopoulou, D; Polehampton, E; Baluteau, J -P; Barlow, M J; Blain, A W; Bock, J; Clements, D L; Coppin, K; Cooray, A; Danielson, A; Dwek, E; Edge, A C; Franceschini, A; Fulton, T; Glenn, J; Griffin, M; Isaak, K; Leeks, S; Lim, T; Naylor, D; Oliver, S J; Page, M J; Perez-Fournon, I; Rowan-Robinson, M; Savini, G; Scott, D; Spencer, L; Valtchanov, I; Vigroux, L; Wright, G S

    2010-01-01

    We present a detailed analysis of the far-IR properties of the bright, lensed, z = 2.3, SMG, SMM J2135-0102, using new observations with Herschel, SCUBA-2 and the VLA. These data allow us to constrain the galaxy's SED and show that it has an intrinsic rest-frame 8-1000um luminosity, L(bol), of (2.3 +/- 0.2) x 10^12 L(sun) and a likely SFR of ~400 M(sun)/yr. The galaxy sits on the far-IR/radio correlation for far-IR-selected galaxies. At ~>70um, the SED can be described adequately by dust components with T(d) ~ 30 and 60K. Using SPIRE's Fourier Transform Spectrometer we report a detection of the [CII] 158um cooling line. If the [CII], CO and far-IR continuum arise in photo-dissociation regions, we derive a characteristic gas density, n ~ 10^3 cm^-3, and a far-UV radiation field, G_0, 10^3x stronger than the Milky Way. L([CII])/L(bol) is significantly higher than in local ULIRGs but similar to the values found in local star-forming galaxies and starburst nuclei. This is consistent with SMM J2135-0102 being powe...

  5. Optical and Near-Infrared Integral Field Spectroscopy of the SCUBA Galaxy N2-850.4

    CERN Document Server

    Swinbank, M; Borys, C; Bower, R; Bunker, A; Chapman, S; Ivison, R; Keel, W; Ramsay-Howat, S; Smail, I; Swinbank, Mark; Smail, Ian; Bower, Richard; Borys, Colin; Chapman, Scott; Blain, Andrew; Ivison, Rob; Ramsay-Howat, Suzie; Keel, William

    2005-01-01

    We present optical and near-infrared integral field spectroscopy of the SCUBA galaxy SMM J163650.43+405734.5 (ELAIS N2 850.4) at z=2.385. We combine Ly-alpha and H-alpha emission line maps and velocity structure with high resolution HST ACS and NICMOS imaging to probe the complex dynamics of this vigorous star-burst galaxy. The imaging data shows a complex morphology, consisting of at least three components separated by ~1'' (8kpc) in projection. When combined with the H-alpha velocity field from UKIRT UIST IFU observations we identify two components whose redshifts are coincident with the systemic redshift, measured from previous CO observations, one of which shows signs of AGN activity. A third component is offset by 220+/-50km/s from the systemic velocity. The total star formation rate of the whole system (estimated from the narrow-line H-alpha and uncorrected for reddening) is 340+/-50Mo/yr. The Ly-alpha emission mapped by the GMOS IFU covers the complete galaxy and is offset by +270+/-40km/s from the sys...

  6. The SCUBA-2 Cosmology Legacy Survey: the submillimetre properties of Lyman break galaxies at z=3-5

    CERN Document Server

    Coppin, K E K; Almaini, O; Arumugam, V; Dunlop, J S; Hartley, W G; Ivison, R J; Simpson, C J; Smith, D J B; Swinbank, A M; Blain, A W; Bourne, N; Bremer, M; Conselice, C; Harrison, C M; Mortlock, A; Chapman, S C; Davies, L J M; Farrah, D; Gibb, A; Jenness, T; Karim, A; Knudsen, K K; Ibar, E; Michałowski, M J; Peacock, J A; Rigopoulou, D; Robson, E I; Scott, D; Stevens, J; van der Werf, P P

    2014-01-01

    We present statistically significant detections at 850um of the Lyman Break Galaxy (LBG) population at z=3, 4, and 5 using data from the Submillimetre Common User Bolometer Array 2 (SCUBA-2) Cosmology Legacy Survey (S2CLS) in the United Kingdom Infrared Deep Sky Survey Ultra Deep Survey (UKIDSS-UDS) field. We employ a stacking technique to probe beneath the survey limit to measure the average 850um flux density of LBGs at z=3, 4, and 5 with typical ultraviolet luminosities of L(1700A)~10^29 erg/s/Hz. We measure 850um flux densities of (0.25 +/- 0.03, (0.41 +/- 0.06), and (0.88 +/- 0.23) mJy respectively, and find that they contribute at most 20 per cent to the cosmic far-infrared background at 850um. Fitting an appropriate range of spectral energy distributions to the z=3, 4, and 5 LBG stacked 24-850um fluxes, we derive infrared (IR) luminosities of L(8-1000um)~3.2, 5.5, and 11.0x10^11 Lsun (corresponding to star formation rates of ~50-200 Msun/yr) respectively. We find that the evolution in the IR luminosity...

  7. Molecular line contamination in the SCUBA-2 450 {\\mu}m and 850 {\\mu}m continuum data

    CERN Document Server

    Drabek, E; Friberg, P; Richer, J; Graves, S; Buckle, J V; Nutter, D; Johnstone, D; Di Francesco, J

    2012-01-01

    Observations of the dust emission using millimetre/submillimetre bolometer arrays can be contaminated by molecular line flux, such as flux from 12CO. As the brightest molecular line in the submillimetre, it is important to quantify the contribution of CO flux to the dust continuum bands. Conversion factors were used to convert molecular line integrated intensities to flux detected by bolometer arrays in mJy per beam. These factors were calculated for 12CO line integrated intensities to the SCUBA-2 850 {\\mu}m and 450 {\\mu}m bands. The conversion factors were then applied to HARP 12CO 3-2 maps of NGC 1333 in the Perseus complex and NGC 2071 and NGC 2024 in the Orion B molecular cloud complex to quantify the respective 12CO flux contribution to the 850 {\\mu}m dust continuum emission. Sources with high molecular line contamination were analysed in further detail for molecular outflows and heating by nearby stars to determine the cause of the 12CO contribution. The majority of sources had a 12CO 3-2 flux contribut...

  8. Bubbles, microparticles, and neutrophil activation: changes with exercise level and breathing gas during open-water SCUBA diving.

    Science.gov (United States)

    Thom, Stephen R; Milovanova, Tatyana N; Bogush, Marina; Yang, Ming; Bhopale, Veena M; Pollock, Neal W; Ljubkovic, Marko; Denoble, Petar; Madden, Dennis; Lozo, Mislav; Dujic, Zeljko

    2013-05-15

    The study goal was to evaluate responses in humans following decompression from open-water SCUBA diving with the hypothesis that exertion underwater and use of a breathing mixture containing more oxygen and less nitrogen (enriched air nitrox) would alter annexin V-positive microparticle (MP) production and size changes and neutrophil activation, as well as their relationships to intravascular bubble formation. Twenty-four divers followed a uniform dive profile to 18 m of sea water breathing air or 22.5 m breathing 32% oxygen/68% nitrogen for 47 min, either swimming with moderately heavy exertion underwater or remaining stationary at depth. Blood was obtained pre- and at 15 and 120 min postdive. Intravascular bubbles were quantified by transthoracic echocardiography postdive at 20-min intervals for 2 h. There were no significant differences in maximum bubble scores among the dives. MP number increased 2.7-fold, on average, within 15 min after each dive; only the air-exertion dive resulted in a significant further increase to 5-fold over baseline at 2 h postdive. Neutrophil activation occurred after all dives. For the enriched air nitrox stationary at depth dive, but not for other conditions, the numbers of postdive annexin V-positive particles above 1 μm in diameter were correlated with intravascular bubble scores (correlation coefficients ∼0.9, P bubbles, MPs, platelet-neutrophil interactions, and neutrophil activation appear to exist, but more study is required to improve confidence in the associations.

  9. Thermal shock in a circumferentially cracked hollow cylinder with cladding

    Science.gov (United States)

    Nied, H. F.

    1984-01-01

    An theoretical analysis is presented which demonstrates the effect of cladding on the thermal resistance of a circumferentially cracked hollow cylinder. The cladding is assumed to be bonded to the inner wall of the hollow cylinder. The axisymmetric circumferential crack may be either embedded in the cylinder wall or may be an edge crack which passes through the clad and opens into the inner wall of the hollow cylinder. The problem is formulated mathematically and a solution is found which is in the form of a single integral equation. The integral equation is solved numerically and yields estimates of transient temperature distributions, thermal stresses in the uncracked cylinder, and stress intensity factors as a function of time for various cladding thickness to cylinder wall thickness ratios. It is shown that yielding of the clad under certain conditions can result in a reduction in the magnitude of the stress intensity factor for the crack tip in the elastic base material.

  10. Effect of Surface Coatings on Cylinders Exposed to Underwater Shock

    Directory of Open Access Journals (Sweden)

    Y.W. Kwon

    1994-01-01

    Full Text Available The response of a coated cylinder (metallic cylinder coated with a rubber material subjected to an underwater explosion is analyzed numerically. The dynamic response of the coated cylinder appears to be adversely affected when impacted by an underwater shock wave under certain conditions of geometry and material properties of the coating. When adversely affected, significant deviations in values of axial stress, hoop stress, and strain are observed. The coated cylinder exhibits a larger deformation and higher internal energy in the metallic material. Rubber coatings appeared to inhibit energy dissipation from the metallic material to the surrounding water medium. A parametric study of various coatings was performed on both aluminum and steel cylinders. The adverse effect of the coating decreased when the stiffness of the rubber layer increased, indicating the existence of a threshold value. The results of this study indicate that the stiffness of the coating is a critical factor to the shock hardening of the coated cylinder.

  11. Adaptronic tools for superfinishing of cylinder bores

    Science.gov (United States)

    Roscher, Hans-Jürgen; Hochmuth, Carsten; Hoffmann, Michael; Praedicow, Michael

    2012-04-01

    Today in the production of internal combustion engines it is possible to make pistons as well as cylinders, for all practical purposes, perfectly round. The negative consequences of the subsequent assembly processes and operation of the engine is that the cylinders and pistons are deformed, resulting in a loss of power and an increase in fuel consumption. This problem can be solved by using an adaptronic tool, which can machine the cylinder to a predetermined nonround geometry, which will deform to the required geometry during assembly and operation of the engine. The article describes the actuatory effect of the tool in conjunction with its measuring and controlling algorithms. The adaptronic tool consists out the basic tool body and three axially-staggered floating cutter groups, these cutter groups consist out of guides, actuators and honing stones. The selective expansion of the tool is realised by 3 piezoelectric multilayer-actuators deployed in a series - parallel arrangement. It is also possible to superimpose actuator expansion on the conventional expansion. A process matrix is created during the processing of the required and actual contour data in a technology module. This is then transferred over an interface to the machine controller where it is finally processed and the setting values for the piezoelectric actuators are derived, after which an amplifier generates the appropriate actuator voltages. A slip ring system on the driveshaft is used to transfer the electricity to the actuators in the machining head. The functioning of the adaptronic form-honing tool and process were demonstrated with numerous experiments. The tool provides the required degrees of freedom to generate a contour that correspond to the inverse compound contour of assembled and operational engines.

  12. Vortex shedding noise of a cylinder with hairy flaps

    OpenAIRE

    Kamps, L.; Geyer, T. F.; Sarradj, E.; Brücker, C.

    2017-01-01

    This study describes the modification of acoustic noise emitted from cylinders in a stationary subsonic flow for a cylinder equipped with flexible hairy flaps at the aft part as a passive way to manipulate the flow and acoustics. The study was motivated by the results from previous water tunnel measurements, which demonstrated that hairy flaps can modify the shedding cycle behind the cylinder and can reduce the wake deficit. In the present study, wind tunnel experiments were conducted on such...

  13. Analysis of a functionally graded piezothermoelastic hollow cylinder

    Institute of Scientific and Technical Information of China (English)

    CHEN Ying; SHI Zhi-fei

    2005-01-01

    A long thick-walled hollow cylinder ofpiezothermoelastic materials was studied in this work. The gradient property of the piezoelectric parameter g31 was taken into account. The theory of elasticity was applied to obtain the exact solutions of the cylinder subjected simultaneously to thermal and electric loadings. As an application, these solutions have been successfully used to study the inverse problems of the material. For comparison, numerical results have been carried out for both graded and double-layered cylinders.

  14. Component masses of young, wide, non-magnetic white dwarf binaries in the Sloan Digital Sky Survey Data Release 7

    Science.gov (United States)

    Baxter, R. B.; Dobbie, P. D.; Parker, Q. A.; Casewell, S. L.; Lodieu, N.; Burleigh, M. R.; Lawrie, K. A.; Külebi, B.; Koester, D.; Holland, B. R.

    2014-06-01

    We present a spectroscopic component analysis of 18 candidate young, wide, non-magnetic, double-degenerate binaries identified from a search of the Sloan Digital Sky Survey Data Release 7 (DR7). All but two pairings are likely to be physical systems. We show SDSS J084952.47+471247.7 + SDSS J084952.87+471249.4 to be a wide DA + DB binary, only the second identified to date. Combining our measurements for the components of 16 new binaries with results for three similar, previously known systems within the DR7, we have constructed a mass distribution for the largest sample to date (38) of white dwarfs in young, wide, non-magnetic, double-degenerate pairings. This is broadly similar in form to that of the isolated field population with a substantial peak around M ˜ 0.6 M⊙. We identify an excess of ultramassive white dwarfs and attribute this to the primordial separation distribution of their progenitor systems peaking at relatively larger values and the greater expansion of their binary orbits during the final stages of stellar evolution. We exploit this mass distribution to probe the origins of unusual types of degenerates, confirming a mild preference for the progenitor systems of high-field-magnetic white dwarfs, at least within these binaries, to be associated with early-type stars. Additionally, we consider the 19 systems in the context of the stellar initial mass-final mass relation. None appear to be strongly discordant with current understanding of this relationship.

  15. Recording Rapidly Changing Cylinder-wall Temperatures

    Science.gov (United States)

    Meier, Adolph

    1942-01-01

    The present report deals with the design and testing of a measuring plug suggested by H. Pfriem for recording quasi-stationary cylinder wall temperatures. The new device is a resistance thermometer, the temperature-susceptible part of which consists of a gold coating applied by evaporation under high vacuum and electrolytically strengthened. After overcoming initial difficulties, calibration of plugs up to and beyond 400 degrees C was possible. The measurements were made on high-speed internal combustion engines. The increasing effect of carbon deposit at the wall surface with increasing operating period is indicated by means of charts.

  16. Cylinder Imbalance Detection of Six Cylinder DI Diesel Engine Using Pressure Variation

    Directory of Open Access Journals (Sweden)

    S.H.Gawande

    2010-04-01

    Full Text Available In this research paper a simplified methodology is presented to detect cylinder imbalance in operating sixcylinder DI diesel engine. The detailed torsional vibration analysis helps to find vibratory frequencies, mode shapes, and vibratory stresses to provide constraints on critical speed in operating engine. The crank shaft is considered to be a rigid body so that the variation of the angular speed could be directly correlated to the cylinder pressure. Actuallythe variation of crank shaft speed has a complex function being influence by torsional stiffness of crank shaft, the mass moment of inertia of reciprocating and rotating masses and the average speed and load on the engine. The information carried by the harmonic order permits to established correlation between measurement and average gaspressure of the engine and to detect torque imbalance and identify faulty cylinder. In this work the detail pressure variation study is carried out on operating six cylinder engine of type SL90 Engine-SL8800TA model manufactured by Kirloskar Oil Engine Pune.

  17. Medical Gas Cylinder with Mismatched Colour and Pin Index

    Directory of Open Access Journals (Sweden)

    Mukherjee S

    2014-08-01

    Full Text Available The medical gas cylinders have various safety features to prevent the administration of wrong gas to the patient. Most of the features have visual impact (colour, label, markings on the cylinder body except pin index system on the cylinder valve, so error in this feature is difficult to analyze and is highly unpredictable. We had received one such cylinder in our institution where all other features (label, colour, marking pointed to nitrous oxide except the pin index which resembled with that of oxygen

  18. Experimental free convection heat transfer from inclined square cylinders

    Science.gov (United States)

    Ali, Mohamed

    2016-10-01

    Natural convection from axisymmetric objects such as vertical or horizontal cylinders and spheres are two dimensional. However, for inclined circular or noncircular cylinders the flow and heat transfer is three dimensional and hence more complex and needs more attention. This study investigates the steady state mechanism of natural convection from inclined square cylinders in air. Five different cylinders of 1 m length, 8 × 8, 7 × 7, 6 × 6, 4 × 4 and 2.5 × 2.5 cm2 cross sections are used. The cylinders are heated using inserted heating element of 6 mm in diameter. Self-adhesive thermocouples are used at the upper, bottom and at one side of the cylinders for temperature measurement. Three inclination angles to the horizontal 30, 45 and 60o are used for each cylinder with uniform heat flux boundary conditions. For each cylinder, about ten heat fluxes are used to generate the heat transfer data. Local and average heat transfer coefficient is determined for each cylinder at each inclination angle for each uniform heat flux. Laminar and transition to turbulent regimes are obtained and characterized. Local critical axial distance where heat transfer coefficient changes the mode is obtained for each heat flux. Local and averaged Nusselt numbers are correlated with the modified Rayleigh numbers for all angles.

  19. Clinical implementation of MR‐guided vaginal cylinder brachytherapy

    National Research Council Canada - National Science Library

    Owrangi, Amir M; Jolly, Shruti; Balter, James M; Cao, Yue; Maturen, Katherine E; Young, Lisa; Zhu, Tong; Prisciandaro, Joann I

    2015-01-01

    ...)‐guided vaginal brachytherapy using commercially available solid applicator models. To test the fidelity of solid applicator models to digitize vaginal cylinder applicators, three datasets were evaluated...

  20. Quantum phase transition in ultra small doubly connected superconducting cylinders

    Science.gov (United States)

    Sternfeld, I.; Koret, R.; Shtrikman, H.; Tsukernik, A.; Karpovski, M.; Palevski, A.

    2008-02-01

    The kinetic energy of Cooper pairs, in doubly connected superconducting cylinders, is a function of the applied flux and the ratio between the diameter of the cylinder and the zero temperature coherence length d/ ξ(0). If d >ξ(0) the known Little-Parks oscillations are observed. On the other hand if d ξ(0), we observed the LP oscillations. In the Al cylinders we did not observe a transition to the superconducting state due to the proximity effect, resulted from an Au layer coating the Al. However, we did observe Altshuler-Aronov-Spivak (h/2e) oscillations in these cylinders.

  1. Stability of Flow around a Cylinder in Plane Poiseuille Flow

    Science.gov (United States)

    Dou, Hua-Shu; Ben, An-Qing; Fluid Mechanics Research Team

    2013-11-01

    Simulation of Navier-Stokes equations is carried out to study the stability of flow around a cylinder in plane Poiseuille flow. The energy gradient method is employed to analyze the mechanism of instability of cylinder wake. The ratio of the channel width to the cylinder diameter is 30, and the Reynolds number based on the cylinder diameter and incoming centerline velocity is 26 and 100, respectively. The incoming flow is given as being laminar. It is found that the instability of the cylinder wake, starting near the front stagnation point upstream. The recirculation zone behind the cylinder has no effect on the stability of the wake. In the wake behind the recirculation zone, the flow stability is controlled by the energy gradient in the shear layer along the two sides of the wake. At high Re, the energy gradient of averaged flow in the channel interacts with the wake vortex, strengthening the wake vortex structure. Due to the large ratio of the channel width to the cylinder diameter, the disturbance caused by the cylinder mainly occurs in the vicinity of the centerline and has little effect on the flow near the wall. The velocity profile on the two sides of the cylinder wake in the downstream channel remains laminar (parabolic profile). Professor in Fluid Mechanics; AIAA Associate Fellow.

  2. Pareter Study of Some Key Structures for Cylinder Head

    Institute of Scientific and Technical Information of China (English)

    张儒华; 左正兴; 曹丽亚; 廖日东

    2004-01-01

    Using the method of the pareter study, some important dimensions of the cylinder head of an internal-combustion engine are analyzed. Under the mechanical load, the variational rules of the von Mises maximum stress on cylinder head are obtained, which are influenced by the thickness of the floor plate, head plate, jobbing sheet, standing partition board, and side plate of inlet port and exhaust port. A hypothesis is verified that there is an ideal matching point ong those above-mentioned main pareters. The quantificational proportion relations, between these key structural pareters and von Mises maximum stress of cylinder head, can provide a good help for the cylinder head's structural design.

  3. An update on corrosion monitoring in cylinder storage yards

    Energy Technology Data Exchange (ETDEWEB)

    Henson, H.M.; Newman, V.S.; Frazier, J.L. [Oak Ridge K-25 Site, TN (United States)

    1991-12-31

    Depleted uranium, from US uranium isotope enrichment activities, is stored in the form of solid uranium hexafluoride (UF{sub 6}) in A285 and A516 steel cylinders designed and manufactured to ASME Boiler and Pressure Vessel Code criteria. In general, storage facilities are open areas adjacent to the enrichment plants where the cylinders are exposed to weather. This paper describes the Oak Ridge program to determine the general corrosion behavior of UF{sub 6} cylinders, to determine cylinder yard conditions which are likely to affect long term storage of this material, and to assess cylinder storage yards against these criteria. This program is targeted at conditions specific to the Oak Ridge cylinder yards. Based on (a) determination of the current cylinder yard conditions, (b) determination of rusting behavior in regions of the cylinders showing accelerated attack, (c) monitoring of corrosion rates through periodic measurement of test coupons placed within the cylinder yards, and (d) establishment of a computer base to incorporate and retain these data, the technical division is working with the enrichment sites to implement an upgraded system for storage of this material until such time as it is used or converted.

  4. Inflation of polymer melts into elliptic and circular cylinders

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Christensen, Jens Horslund; Gøttsche, Søren

    2000-01-01

    A thin sheet (membrane) of the polymeric material is clamped between a Teflon-coated thermostated plate and a thermostated aluminium cylinder. By applying thermostated air through the plate, the polymer membrane deforms into an elliptic or a circular cylinder. The position of the top of the infla......A thin sheet (membrane) of the polymeric material is clamped between a Teflon-coated thermostated plate and a thermostated aluminium cylinder. By applying thermostated air through the plate, the polymer membrane deforms into an elliptic or a circular cylinder. The position of the top...

  5. ANALYTICAL AND MATHCAD INTERSECTION BETWEEN TWO PERPENDICULAR AXES CYLINDERS

    Directory of Open Access Journals (Sweden)

    PETRESCU Ligia

    2015-06-01

    Full Text Available The intersection of two surfaces is a common line to both surfaces. This line is often called transition line. The authors propose an analytical and a computer graphics intersection between two perpendicular axes cylinders. The analytical expression of such intersection will be obtained and transposed on the development of one cylinder. The distance between the two cylinders axes is essential in the aspect of the transition line. This transition line can be also obtained, using the computer, by the MathCAD programme. Some samples are relevant in this subject, according to the distance between the cylinders.

  6. Prediction of External Corrosion for Steel Cylinders--2007 Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmoyer, Richard L [ORNL

    2008-01-01

    Depleted uranium hexafluoride (DUF{sub 6}) is stored in over 62,000 containment cylinders at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and at the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. Over 4,800 of the cylinders at Portsmouth were recently moved there from the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. The cylinders range in age up to 56 years and come in various models, but most are 48-inch diameter 'thin-wall'(312.5 mil) and 'thick-wall' (625 mil) cylinders and 30-inch diameter '30A' (including '30B') cylinders with 1/2-inch (500 mil) walls. Most of the cylinders are carbon steel, and they are subject to corrosion. The United States Department of Energy (DOE) manages the cylinders to maintain them and the DUF{sub 6} they contain. Cylinder management requirements are specified in the System Requirements Document (LMES 1997a), and the activities to fulfill them are specified in the System Engineering Management Plan (LMES 1997b). This report documents activities that address DUF{sub 6} cylinder management requirements involving measuring and forecasting cylinder wall thicknesses. As part of these activities, ultrasonic thickness (UT) measurements are made on samples of cylinders. For each sampled cylinder, multiple measurements are made in an attempt to find, approximately, the minimum wall thickness. Some cylinders have a skirt, which is an extension of the cylinder wall to protect the head (end) and valve. The head/skirt interface crevice is thought to be particularly vulnerable to corrosion, and for some skirted cylinders, in addition to the main body UT measurements, a separate suite of measurements is also made at the head/skirt interface. The main-body and head/skirt minimum thickness data are used to fit models relating minimum thickness to cylinder age, nominal thicknesses, and cylinder functional groups defined in terms of plant site, storage yard

  7. Improvement on Cylinder-to-Cylinder Variation in PCCI Engines Using Variable Start of Injection and Exhaust Valve Closing Timings

    OpenAIRE

    Axelsson, Aðalsteinn; Shaver, Greg

    2013-01-01

    Premixed charge compression ignition (PCCI) is widely considered to be a possible method of meeting increasingly strict emissions regulations in internal combustion engines. PCCI can reduce harmful emissions substantially and at the same time increase efficiency relative to conventional combustion modes. Because of the nature of PCCI, changes in in-cylinder conditions have a greater impact than in conventional diesel engines. Therefore cylinder to cylinder variations are amplified which leads...

  8. The capillary interaction between two vertical cylinders

    KAUST Repository

    Cooray, Himantha

    2012-06-27

    Particles floating at the surface of a liquid generally deform the liquid surface. Minimizing the energetic cost of these deformations results in an inter-particle force which is usually attractive and causes floating particles to aggregate and form surface clusters. Here we present a numerical method for determining the three-dimensional meniscus around a pair of vertical circular cylinders. This involves the numerical solution of the fully nonlinear Laplace-Young equation using a mesh-free finite difference method. Inter-particle force-separation curves for pairs of vertical cylinders are then calculated for different radii and contact angles. These results are compared with previously published asymptotic and experimental results. For large inter-particle separations and conditions such that the meniscus slope remains small everywhere, good agreement is found between all three approaches (numerical, asymptotic and experimental). This is as expected since the asymptotic results were derived using the linearized Laplace-Young equation. For steeper menisci and smaller inter-particle separations, however, the numerical simulation resolves discrepancies between existing asymptotic and experimental results, demonstrating that this discrepancy was due to the nonlinearity of the Laplace-Young equation. © 2012 IOP Publishing Ltd.

  9. CYLINDER LENS ALIGNMENT IN THE LTP

    Energy Technology Data Exchange (ETDEWEB)

    TAKACS, P.Z.

    2005-07-26

    The Long Trace Profiler (LTP), is well-suited for the measurement of the axial figure of cylindrical mirrors that usually have a long radius of curvature in the axial direction but have a short radius of curvature in the sagittal direction. The sagittal curvature causes the probe beam to diverge in the transverse direction without coming to a focus on the detector, resulting in a very weak signal. It is useful to place a cylinder lens into the optical system above the mirror under test to refocus the sagittal divergence and increase the signal level. A positive cylinder lens can be placed at two positions above the surface: the Cat's Eye reflection position and the Wavefront-Matching position. The Cat's Eye position, is very tolerant to mirror misalignment, which is not good if absolute axial radius of curvature is to be measured. Lateral positioning and rotational misalignments of lens and the mirror combine to produce unusual profile results. This paper looks at various alignment issues with measurements and by raytrace simulations to determine the best strategy to minimize radius of curvature errors in the measurement of cylindrical aspheres.

  10. Effects of Cylinder Radius, Setover and Heel-Toe Difference on Cylinder-Flat Gauge of a Card

    Institute of Scientific and Technical Information of China (English)

    SUN peng-zi; JU Yan-qing; ZHANG Ming-guang

    2007-01-01

    In order to provide manufacturers of carding machines and relevant accessories with theoretical references, how cylinder radius, setover and heel-toe difference affect cylinder-flat gauge of a carding machine was theoretically studied. The relationship between cylinder-flat gauge and cylinder radius, setover and heel-toe difference was geometrically discussed. Numerical calculation and illustration about the relationship were made with MATLAB in accordance with practical settings. A general formula about the relationship is derived. A concept, the small-gauge zone length, has been defined for the first time, and some relevant results thus obtained. Given setover and heel-toe difference, the greater the cylinder radius, the greater the average gauge. If a smaller overall cylinder-flat gauge is desirable, it is not necessary to emphasize the tangential direction of the heel of clothed surface to the cylinder. Their intersection within a small zone is acceptable. In many cases, small-gauge zone can reduce average gauge which may be helpful to the carding action; given cylinder radius and setover, the smaller the heel-toe difference, the more helpful to reduce the overall gauge; given cylinder radius and heel-toe difference, the small-gauge zone length will increase with the increase of setover, so does the difference between the smallest gauge and outlet gauge.

  11. Prediction of External Corrosion for Steel Cylinders--2004 Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmoyer, RLS

    2004-07-07

    Depleted uranium hexafluoride (UF{sub 6}) is stored in over 60,000 steel cylinders at the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee, at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and at the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The cylinders range in age from 4 to 53 years. Although when new the cylinders had wall thicknesses specified to within manufacturing tolerances, over the years corrosion has reduced their actual wall thicknesses. The UF{sub 6} Cylinder Project is managed by the United States Department of Energy (DOE) to safely maintain the UF{sub 6} and the cylinders containing it. This report documents activities that address UF{sub 6} Cylinder Project requirements and actions involving forecasting cylinder wall thicknesses. These requirements are delineated in the System Requirements Document (LMES 1997a), and the actions needed to fulfill them are specified in the System Engineering Management Plan (LMES 1997b). The report documents cylinder wall thickness projections based on models fit to ultrasonic thickness (UT) measurement data. UT data is collected at various locations on randomly sampled cylinders. For each cylinder sampled, the minimum UT measurement approximates the actual minimum thickness of the cylinder. Projections of numbers of cylinders expected to fail various thickness criteria are computed from corrosion models relating minimum wall thickness to cylinder age, initial thickness estimates, and cylinder subpopulations defined in terms of plant site, yard, top or bottom storage positions, nominal thickness, etc. In this report, UT data collected during FY03 is combined with UT data collected in earlier years (FY94-FY02), and all of the data is inventoried chronologically and by various subpopulations. The UT data is used to fit models of maximum pit depth and minimum thickness, and the fitted models are used to extrapolate minimum thickness estimates into the future and in

  12. UF{sub 6} pressure excursions during cylinder heating

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.G. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    As liquid UF{sub 6} inside a cylinder changes from a liquid to a solid, it forms a porous solid which occupies approximately the same volume as that of the liquid before cooling. Simultaneously as the liquid cools, UF{sub 6} vapor in the cylinder ullage above the liquid desublimes on the upper region of the inner cylinder wall. This solid is a dense, glass-like material which can accumulate to a significant thickness. The thickness of the solid coating on the upper cylinder wall and directly behind the cylinder valve area will vary depending on the conditions during the cooling stage. The amount of time lapsed between UF{sub 6} solidification and UF{sub 6} liquefaction can also affect the UF{sub 6} coating. This is due to the daily ambient heat cycle causing the coating to sublime from the cylinder wall to cooler areas, thus decreasing the thickness. Structural weakening of the dense UF{sub 6} layer also occurs due to cylinder transport vibration and thermal expansion. During cylinder heating, the UF{sub 6} nearest the cylinder wall will liquefy first. As the solid coating behind the cylinder valve begins to liquefy, it results in increased pressure depending upon the available volume for expansion. At the Paducah Gaseous Diffusion Plant (PGDP) during the liquefaction of the UF{sub 6} in cylinders in the UF{sub 6} feed and sampling autoclaves, this pressure increase has resulted in the activation of the systems rupture discs which are rated at 100 pounds per square inch differential.

  13. Critical point drying: contamination in transitional fluid supply cylinders.

    Science.gov (United States)

    Hoagland, K D; Rosowski, J R; Cohen, A L

    1980-01-01

    We call attention to the occurrence of an oily residue in the CPD bomb after critical point drying, as well as the presence of rust, dirt, and an oily residue in CO2 and Freon supply cylinders. Bottled gas is often tested for purity once after manufacturing and then is pumped and stored, perhaps several times, before the consumer's cylinders are filled. The cylinders may be in use for over 40 years, and may never be chemically cleaned, although they are hydrostatically pressure tested every five years, with the date of each test stamped on the cylinder. To the bottled gas industry we recommend regular inspection of tanks for bottom contamination, and vacuum and chemical cleaning when contamination is found. To users of bottled gas for critical point drying, we recommend becoming aware of the procedures of cylinder inspection, cleaning, and circulation among users. We suggest reporting to the gas supplier any contamination produced by inadvertently backfilling the supply cylinder. Although a common awareness of the problem of supply cylinder residues should lead to failures, the best assurance of clean, oil-free, dry liquid CO2 and other transitional fluids may be in the development of in-line filters which would remove particles, oil and moisture between the supply cylinder and the CPD bomb. We also suggest the use of gas grades higher than commercial, such as welding anhydrous (CO2) or specialty gases.

  14. Turbulent Taylor-Couette flow with stationary inner cylinder

    CERN Document Server

    Ostilla-Monico, Rodolfo; Lohse, Detlef

    2016-01-01

    A series of direct numerical simulations of Taylor-Couette (TC) flow, the flow between two coaxial cylinders, with the outer cylinder rotating and the inner one fixed, were performed. Three cases, with outer cylinder Reynolds numbers $Re_o$ of $Re_o=5.5\\cdot10^4$, $Re_o=1.1\\cdot10^5$ and $Re_o=2.2\\cdot10^5$ were considered. The radius ratio $\\eta=r_i/r_o$ was fixed to $\\eta=0.909$ to mitigate the effects of curvature. The vertical aspect ratio $\\Gamma$ was fixed to $\\Gamma=2.09$. Being linearly stable, outer cylinder rotation TC flow is known to have very different behavior than pure inner cylinder rotation TC flow. Here, we find that the flow nonetheless becomes turbulent, but the torque required to drive the cylinders and level of velocity fluctuations was found to be smaller than those for pure inner cylinder rotation at comparable Reynolds numbers. The mean angular momentum profiles showed a large gradient in the bulk, instead of the constant angular momentum profiles of pure inner cylinder rotation. The ...

  15. Prediction of External Corrosion for Steel Cylinders - 1998 Report

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, B.F.

    1998-01-01

    The United States Department of Energy (DOE) currently manages the UF, Cylinder Project. The project was formed to maintain and safely manage depleted uranium hexafluoride (UF{sub 6}) stored in approximately 50,000 carbon steel cylinders. The cylinders located at three DOE sites: the K-25 site at Oak Ridge, Tennessee (K-25); the Paducah Gaseous Diffusion Plant in Paducah, Kentucky (PGDP), and the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The System Requirements Document (SRD) (LMES 1997a) delineates the requirements of the project. The appropriate actions needed to fulfill these requirements are then specified within the System Engineering Management Plan (SEMP) (LMES 1997b). The report presented herein documents activities that in whole or in part satisfy specific requirements and actions stated in the UF{sub 6} Cylinder Project SRD and SEMP with respect to forecasting cylinder conditions. The wall thickness projections made in this report are based on the assumption that the corrosion trends noted will continue. Some activities planned may substantially reduce the rate of corrosion, in which case the results presented here are conservative. The results presented here are intended to supercede and enlarge the scope of those presented previously (Lyon 1995,1996, 1997). In particular, projections are made for thin-walled cylinders (nominal initial thickness 312.5 mils) and thick-walled cylinders (nominal initial thickness 625 mils). In addition, a preliminary analysis is conducted for the minimum thickness at the head/skirt interface for skirted cylinders.

  16. 76 FR 38697 - High Pressure Steel Cylinders From China

    Science.gov (United States)

    2011-07-01

    ..., 2011 (76 FR 28807). The conference was held in Washington, DC, on June 1, 2011, and all persons who... COMMISSION High Pressure Steel Cylinders From China Determinations On the basis of the record \\1\\ developed... injured by reason of imports from China of high pressure steel cylinders, provided for in subheading...

  17. 77 FR 37712 - High Pressure Steel Cylinders From China

    Science.gov (United States)

    2012-06-22

    ... Commission, Washington, DC, and by publishing the notice in the Federal Register on January 23, 2012 (77 FR... COMMISSION High Pressure Steel Cylinders From China Determinations On the basis of the record \\1\\ developed... imports of high pressure steel cylinders from China, provided for in subheading 7311.00.00 of...

  18. 30 CFR 56.16006 - Protection of gas cylinder valves.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Protection of gas cylinder valves. 56.16006 Section 56.16006 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Storage and Handling § 56.16006 Protection of gas cylinder valves. Valves on compressed gas...

  19. 30 CFR 57.16006 - Protection of gas cylinder valves.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Protection of gas cylinder valves. 57.16006 Section 57.16006 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Storage and Handling § 57.16006 Protection of gas cylinder valves. Valves on compressed gas...

  20. Temperature Profile of a Fluid between Two Rotating Porous Cylinders

    Directory of Open Access Journals (Sweden)

    Bal Krishan

    1970-07-01

    Full Text Available An exact expression for the temperature profile between two concentric rotating porous cylinders has been obtained. The results are presented graphically. For the wide gap, there is a sharp rise in temperature when the ratio between the angular velocities of the outer and the inner cylinders tends to zero.

  1. Modeling Heat and Mass Transfer from Fabric-Covered Cylinders

    Directory of Open Access Journals (Sweden)

    Phillip Gibson

    2009-03-01

    Full Text Available Fabric-covered cylinders are convenient analogs forclothing systems. The geometry is well defined andincludes many of the effects that are important ingarments. Fabric-covered cylinder models are usedin conjunction with laboratory measurements ofmaterial properties to calculate heat and mass transferproperties of clothing under specific conditions ofenvironmental wind speed, temperature, and relativehumidity.

  2. Unsteady Viscous Flow over an Expanding Stretching Cylinder

    Institute of Scientific and Technical Information of China (English)

    方铁钢; 章骥; 钟永芳; 陶华

    2011-01-01

    We study the viscous How over an expanding stretching cylinder. The solution is exact to the Navier-Stokes equations. The stretching velocity of the cylinder is proportional to the axial distance from the origin and decreases with time. There exists a unique solution for the How with all the studied values of Reynolds number and the unsteadiness parameter. Reversal Hows exist for an expanding stretching cylinder. The velocity decays faster for a larger Reynolds number and a more rapidly expanding cylinder.%We study the viscous flow over an expanding stretching cylinder.The solution is exact to the Navier-Stokes equations.The stretching velocity of the cylinder is proportional to the axial distance from the origin and decreases with time.There exists a unique solution for the flow with all the studied values of Reynolds number and the unsteadiness parameter.Reversal flows exist for an expanding stretching cylinder.The velocity decays faster for a larger Reynolds number and a more rapidly expanding cylinder.

  3. Mobile Robot Localization by Remote Viewing of a Colored Cylinder

    Science.gov (United States)

    Volpe, R.; Litwin, T.; Matthies, L.

    1995-01-01

    A system was developed for the Mars Pathfinder rover in which the rover checks its position by viewing the angle back to a colored cylinder with different colors for different angles. The rover determines distance by the apparent size of the cylinder.

  4. Poiseuille flow-induced vibrations of two cylinders in tandem

    Science.gov (United States)

    Lin, Jianzhong; Jiang, Renjie; Chen, Zhongli; Ku, Xiaoke

    2013-07-01

    Laminar flows past two tandem cylinders which are free to move transversely in a parallel-wall channel were studied numerically by the lattice Boltzmann method. With fixed Reynolds number Re=100, blockage ratio β=1/4 and structural damping ξ=0, the effect of streamwise separation between two cylinders at a range of S/D=[1.1, 10] on the motions of cylinders and fluids was studied for both mass ratios of m(*)=1 and m(*)=0.1. A variety of distinct vibration regimes involving periodic, quasi-periodic and non-periodic vibrations with corresponding flow patterns were observed. A detailed analysis of the vibration amplitudes, vibration frequencies and relative equilibrium positions for both mass ratios demonstrated that as S/D increases, the interaction of the two cylinders first enhances and then reduces. In the strong coupling regime, both cylinders oscillate periodically around the centerline of the channel with large vibration amplitudes and high vibration frequencies. By comparing with the case of an isolated cylinder, a further study indicated that the gap flow plays an important role in such a dynamic system, and the vortex cores formation behind the front cylinder causes the interaction of the cylinders decouple rapidly. Based on the present observations, such a dynamic model system can be considered as a novel type of vortex-induced vibrations (VIV) and is expected to find applications in fluid mixing and heat transfer.

  5. Curing A Large Composite Cylinder Without An Autoclave

    Science.gov (United States)

    Frazer, Robert E.

    1992-01-01

    Proposed technique provides application of heat and pressure to cure fiber-wound composite cylinder too large to fit in autoclave. Tube wound around cylinder applies pressure. Blanket distributes pressure. Pressure expels gas bubbles from material. Heat applied by conventional methods.

  6. 76 FR 77964 - High Pressure Steel Cylinders From the People's Republic of China: Preliminary Determination of...

    Science.gov (United States)

    2011-12-15

    ...'' or ``affiliated persons'': (A) Members of a family, including brothers and sisters (whether by the... International Trade Administration High Pressure Steel Cylinders From the People's Republic of China... Commerce (``Department'') preliminarily determines that high pressure steel cylinders (``steel cylinders...

  7. Effect of constant heat flux at outer cylinder on stability of viscous ...

    African Journals Online (AJOL)

    DR OKE

    dimensional linear stability analysis of the Couette flow between two axial cylinders for ... variable or constant heat flux at the inner cylinder while the outer cylinder is ... differential equations have been obtained to govern the stability of the ...

  8. Imaging of room-temperature ferromagnetic nano-domains at the surface of a non-magnetic oxide

    Science.gov (United States)

    Taniuchi, T.; Motoyui, Y.; Morozumi, K.; Rödel, T. C.; Fortuna, F.; Santander-Syro, A. F.; Shin, S.

    2016-06-01

    Two-dimensional electron gases at oxide surfaces or interfaces show exotic ordered states of matter, like superconductivity, magnetism or spin-polarized states, and are a promising platform for alternative oxide-based electronics. Here we directly image a dense population of randomly distributed ferromagnetic domains of ~40 nm typical sizes at room temperature at the oxygen-deficient surface of SrTiO3, a non-magnetic transparent insulator in the bulk. We use laser-based photoemission electron microscopy, an experimental technique that gives selective spin detection of the surface carriers, even in bulk insulators, with a high spatial resolution of 2.6 nm. We furthermore find that the Curie temperature in this system is as high as 900 K. These findings open perspectives for applications in nano-domain magnetism and spintronics using oxide-based devices, for instance through the nano-engineering of oxygen vacancies at surfaces or interfaces of transition-metal oxides.

  9. Non-Equilibrium Chemistry of Dynamically Evolving Prestellar Cores: I. Basic Magnetic and Non-Magnetic Models and Parameter Studies

    CERN Document Server

    Tassis, Konstantinos; Yorke, Harold W; Turner, Neal

    2011-01-01

    We combine dynamical and non-equilibrium chemical modeling of evolving prestellar molecular cloud cores, and explore the evolution of molecular abundances in the contracting core. We model both magnetic cores, with varying degrees of initial magnetic support, and non-magnetic cores, with varying collapse delay times. We explore, through a parameter study, the competing effects of various model parameters in the evolving molecular abundances, including the elemental C/O ratio, the temperature, and the cosmic-ray ionization rate. We find that different models show their largest quantitative differences at the center of the core, whereas the outer layers, which evolve slower, have abundances which are severely degenerate among different dynamical models. There is a large range of possible abundance values for different models at a fixed evolutionary stage (central density), which demonstrates the large potential of chemical differentiation in prestellar cores. However, degeneracies among different models, compou...

  10. The non-magnetic collapsed tetragonal phase of CaFe2As2 and superconductivity in the iron pnictides

    Science.gov (United States)

    Soh, J. H.; Tucker, G. S.; Pratt, D. K.; Abernathy, D. L.; Stone, M. B.; Ran, S.; Bud'Ko, S. L.; Canfield, P. C.; Kreyssig, A.; McQueeney, R. J.; Goldman, A. I.

    2014-03-01

    The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the non-superconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is non-magnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds. Work at the Ames Laboratory was supported by the Department of Energy, Basic Energy Sciences. Work at ORNL's Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences.

  11. Rotating cylinder drag balance with application to riblets

    Science.gov (United States)

    Hall, T.; Joseph, D.

    2000-12-01

    Experimental results are reported and discussed for a rotating cylinder drag balance designed to predict drag reduction by surfaces like riblets. The apparatus functions by measuring the torque applied to the inner cylinder by a fluid, such as water, that is set in motion by the controlled rotation of the outer cylinder. The instrument was validated by calibration for laminar flow and comparison of turbulent flow results to the those of G. I. Taylor. The ability to predict drag reduction was demonstrated by testing 114 m symmetric sawtooth riblets, which gave a maximum reduction of about 5% and an overall drag reduction range of 5cylinder surface and to use cylinders for which the curvature of the flow is minimized.

  12. ``Reverse'' Lock-in Regime on a Freely Oscillating Cylinder

    Science.gov (United States)

    Atsavapranee, P.; Voorhees, A. V.; Benaroya, H.; Wei, T.

    1998-11-01

    DPIV and flow visualizations were used to characterize the flow in the near wake of a freely oscillating cylinder. A rigid cylinder with a low mass ratio was fixed at one end to a leaf spring and free to oscillate, pendulum-like, at the other end in the cross stream plane. It was found that only a subset of the synchronization range follows the behavior of a ``classical'' lock-in, i.e., when the difference between the natural Strouhal frequency and the natural frequency of the cylinder is small enough, vortex shedding frequency deviates from the linear Strouhal dependence and follows instead the cylinder natural frequency. However, over a range of flow speed in which the response amplitude of the cylinder is significant, it was found that the frequency of oscillation and of vortex shedding follow instead the natural Strouhal frequency, instead of the mechanical natural frequency.

  13. Acoustic resonances in cylinder bundles oscillating in a compressibile fluid

    Energy Technology Data Exchange (ETDEWEB)

    Lin, W.H.; Raptis, A.C.

    1984-12-01

    This paper deals with an analytical study on acoustic resonances of elastic oscillations of a group of parallel, circular, thin cylinders in an unbounded volume of barotropic, compressible, inviscid fluid. The perturbed motion of the fluid is assumed due entirely to the flexural oscillations of the cylinders. The motion of the fluid disturbances is first formulated in a three-dimensional wave form and then casted into a two-dimensional Helmholtz equation for the harmonic motion in time and in axial space. The acoustic motion in the fluid and the elastic motion in the cylinders are solved simultaneously. Acoustic resonances were approximately determined from the secular (eigenvalue) equation by the method of successive iteration with the use of digital computers for a given set of the fluid properties and the cylinders' geometry and properties. Effects of the flexural wavenumber and the configuration of and the spacing between the cylinders on the acoustic resonances were thoroughly investigated.

  14. The Characteristic of Thermoelastic Waves in Transversely Isotropic Finite Cylinders

    Directory of Open Access Journals (Sweden)

    Bai Hao

    2017-01-01

    Full Text Available A theoretical as well as a numerical investigation of the propagation of thermoelastic waves and vibration of transversely isotropic cylinders of finite length is discussed. Lord-Shulman theory is adopted here to model the thermoelastic deformation of cylinders. A semi analytical finite element (SAFE method is employed to study dispersion of thermoelastic waves and natural frequencies of vibration of finite cylinders with traction free curved surfaces having both ends insulated and constrained by frictionless rigid walls. Numerical results obtained by the SAFE method for the frequencies of vibration of a sapphire rod are found to be in excellent agreement with published results. Natural frequencies of vibration for first three axisymmetric and asymmetric modes are presented graphically for a silicon nitride thermoelastic cylinder. Also, numerical results showing dispersion of both propagating and evanescent circumferential waves in infinite and finite cylinders are presented also.

  15. Investigation of breached depleted UF sub 6 cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Barber, E.J.; Butler, T.R.; DeVan, J.H.; Googin, J.M.; Taylor, M.S.; Dyer, R.H.; Russell, J.R.

    1991-09-01

    In June 1990, during a three-site inspection of cylinders being used for long-term storage of solid depleted UF{sub 6}, two 14-ton steel cylinders at Portsmouth, Ohio, were discovered with holes in the barrel section of the cylinders. Both holes, concealed by UF{sub 4} reaction products identical in color to the cylinder coating, were similarly located near the front stiffening ring. The UF{sub 4} appeared to have self-sealed the holes, thus containing nearly all of the uranium contents. Martin Marietta Energy Systems, Inc., Vice President K.W. Sommerfeld immediately formed an investigation team to: (1) identify the most likely cause of failure for the two breached cylinders, (2) determine the impact of these incidents on the three-site inventory, and (3) provide recommendations and preventive measures. This document discusses the results of this investigation.

  16. Investigation of breached depleted UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Barber, E.J.; Butler, T.R.; DeVan, J.H.; Googin, J.M.; Taylor, M.S.; Dyer, R.H.; Russell, J.R.

    1991-09-01

    In June 1990, during a three-site inspection of cylinders being used for long-term storage of solid depleted UF{sub 6}, two 14-ton steel cylinders at Portsmouth, Ohio, were discovered with holes in the barrel section of the cylinders. Both holes, concealed by UF{sub 4} reaction products identical in color to the cylinder coating, were similarly located near the front stiffening ring. The UF{sub 4} appeared to have self-sealed the holes, thus containing nearly all of the uranium contents. Martin Marietta Energy Systems, Inc., Vice President K.W. Sommerfeld immediately formed an investigation team to: (1) identify the most likely cause of failure for the two breached cylinders, (2) determine the impact of these incidents on the three-site inventory, and (3) provide recommendations and preventive measures. This document discusses the results of this investigation.

  17. Scattering characteristics of conducting cylinder coated with nonuniform magnetized ferrite

    Institute of Scientific and Technical Information of China (English)

    Hu Bin-Jie; Edward Yung Kai-Ning; Zhang Jun; Toutain Serge

    2005-01-01

    An analytical technique, referred to as the scattering matrix method (SMM), is developed to analyse the scattering of a planar wave from a conducting cylinder coated with nonuniform magnetized ferrite. The SMM solution for the nonuniform ferrite coating can be reduced to the expressions for the scattering and penetrated coefficients in four particular cases: nonuniform magnetized ferrite cylinder, uniform magnetized ferrite-coated conducting cylinder, uniform ferrite cylinder as well as homogeneous dielectric-coated conducting cylinder. The resonant condition for the nonuniform ferrite coating is obtained. The distinctive differences in scattering between the nonuniform ferrite coating and the nonuniform dielectric coating are demonstrated. The effects of applied magnetic fields and wave frequencies on the scattering characteristics for two types of the linear profiles are revealed.

  18. Magnetic properties and the effect of non-magnetic impurities in the quasi-2D quantum magnet

    Science.gov (United States)

    Khuntia, P.; Dey, T.; Mahajan, A. V.

    2016-09-01

    We present synthesis, x-ray diffraction, magnetisation and specific heat studies on the quasi-two-dimensional (2D) S = 1/2 antiferromagnet (CuCl)LaNb2O7 and its doping analogues (Cu1-x Zn x Cl)LaNb2O7 (0 ≤ x ≤ 0.05), (Cu0.95Mg0.05Cl)LaNb2O7, and (CuCl)La1-y Ba y Nb2O7 (0 ≤ y ≤ 0.10). The magnetic susceptibility and specific heat of the parent compound and its isovalent or hetereovalent counterparts do not display any signature of magnetic ordering down to 1.8 K. The parent compound and its doping variants exhibit spin-singlet behaviour with a finite gap in the spin excitation spectrum due to dimerisation of the dominant intradimer interactions as evidenced from our magnetic susceptibility and specific heat data. The systematic increase of magnetic susceptibility at low temperature with non-magnetic Zn2+ and Mg2+ (S = 0) substitution at the Cu2+ site reflect that impurities induce local moments around the non-magnetic sites. While heterovalent Ba2+ substitution at the La3+ site do not result in mobile holes but rather give rise to a Curie term in the susceptibility due to localisation. The low value of spin S = 1/2, and absence of long range ordering or spin freezing, and the presence of competing exchange interactions hold special significance in hosting novel magnetic properties in this class of quasi-2D quantum material.

  19. Fluid flows in a librating cylinder

    CERN Document Server

    Sauret, Alban; Bars, Michael Le; Dizès, Stéphane Le; 10.1063/1.3680874

    2012-01-01

    The flow in a cylinder driven by time harmonic oscillations of the rotation rate, called longitudinal librations, is investigated. Using a theoretical approach and axisymmetric numerical simulations, we study two distinct phenomena appearing in this librating flow. First, we investigate the occurrence of a centrifugal instability near the oscillating boundary, leading to the so-called Taylor-G\\"ortler vortices. A viscous stability criterion is derived and compared to numerical results obtained for various libration frequencies and Ekman numbers. The strongly nonlinear regime well above the instability threshold is also documented. We show that a new mechanism of spontaneous generation of inertial waves in the bulk could exist when the sidewall boundary layer becomes turbulent. Then, we analyse the librating flow below the instability threshold and characterize the mean zonal flow correction induced by the nonlinear interaction of the boundary layer flow with itself. In the frequency regime where inertial mode...

  20. Material point method simulations of fragmenting cylinders

    CERN Document Server

    Banerjee, Biswajit

    2012-01-01

    Most research on the simulation of deformation and failure of metals has been and continues to be performed using the finite element method. However, the issues of mesh entanglement under large deformation, considerable complexity in handling contact, and difficulties encountered while solving large deformation fluid-structure interaction problems have led to the exploration of alternative approaches. The material point method uses Lagrangian solid particles embedded in an Eulerian grid. Particles interact via the grid with other particles in the same body, with other solid bodies, and with fluids. Thus, the three issues mentioned in the context of finite element analysis are circumvented. In this paper, we present simulations of cylinders which fragment due to explosively expanding gases generated by reactions in a high energy material contained inside. The material point method is the numerical method chosen for these simulations discussed in this paper. The plastic deformation of metals is simulated using ...

  1. Network design for cylinder gas distribution

    Directory of Open Access Journals (Sweden)

    Tejinder Pal Singh

    2015-01-01

    Full Text Available Purpose: Network design of the supply chain is an important and strategic aspect of logistics management. In this paper, we address the network design problem specific to packaged gases (cylinder supply chain. We propose an integrated framework that allows for the determination of the optimal facility locations, the filling plant production capacities, the inventory at plants and hubs, and the number of packages to be routed in primary and secondary transportation. Design/methodology/approach: We formulate the problem as a mixed integer program and then develop a decomposition approach to solve it. We illustrate the proposed framework with numerical examples from real-life packaged gases supply chain. The results show that the decomposition approach is effective in solving a broad range of problem sizes. Findings: The main finding of this paper is that decomposing the network design problem into two sub-problems is very effective to tackle the real-life large scale network design problems occurring in cylinder gas distribution by optimizing strategic and tactical decisions and approximating the operational decisions. We also benchmark the results from the decomposition approach by solving the complete packaged gases network design model for smaller test cases. Originality/value: The main contribution of our work is that it integrates supply chain network design decisions without fixing the fillings plant locations with inventory and resource allocation decisions required at the plants. We also consider the transportation costs for the entire supply chain including the transhipment costs among different facilities by deciding the replenishment frequency.

  2. The Federal Cylinder Project: A Guide to Field Cylinder Collections in Federal Agencies. Volume 8, Early Anthologies.

    Science.gov (United States)

    Lee, Dorothy Sara, Ed; And Others

    This catalog describes wax cylinder recordings of music collected by two pioneers in ethnomusicology. The 101 cylinders in the Benjamin Ives Gilman Collection recorded at the 1893 World's Columbian Exposition in Chicago contain Fijian, Samoan, Uvean, Javanese, Turkish, and Kwakiutl or Vancouver Island Indian music. The Gilman Collection is…

  3. Formation of whispering gallery modes by scattering of an electromagnetic plane wave by two cylinders

    Science.gov (United States)

    Abramov, Arnold; Kostikov, Alexander

    2017-03-01

    We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder.

  4. FORCE REDUCTION OF FLOW AROUND A SINUSOIDAL WAVY CYLINDER

    Institute of Scientific and Technical Information of China (English)

    ZOU Lin; LIN Yu-feng

    2009-01-01

    A large eddy simulation of cross-flow around a sinusoidal wavy cylinder at Re=3000 was performed and the load cell measurement was introduced for the validation test. The mean flow field and the near wake flow structures were presented and compared with those for a circular cylinder at the same Reynolds number. The mean drag coefficient for the wavy cylinder is smaller than that for a corresponding circular cylinder due to the formation of a longer wake vortex generated by the wavy cylinder. The fluctuating lift coefficient of the wavy cylinder is also greatly reduced. This kind of wavy surface leads to the formation of 3-D free shear layers which are more stable than purely 2-D free shear layers. Such free shear layers only roll up into mature vortices at further downstream position and significantly modify the near wake structures and the pressure distributions around the wavy cylinder. Moreover, the simulations in laminar flow condition were also performed to investigate the effect of Reynolds number on force reduction control.

  5. The SCUBA-2 Cosmology Legacy Survey: blank-field number counts of 450um-selected galaxies and their contribution to the cosmic infrared background

    CERN Document Server

    Geach, J E; Coppin, K E K; Dunlop, J S; Halpern, M; Smail, Ian; van der Werf, P; Serjeant, S; Farrah, D; Roseboom, I; Targett, T; Arumugam, V; Asboth, V; Blain, A; Chrysostomou, A; Clarke, C; Ivison, R J; Jones, S L; Karim, A; Mackenzie, T; Meijerink, R; Michalowski, M J; Scott, D; Simpson, J; Swinbank, A M; Alexander, D; Almaini, O; Aretxaga, I; Best, P; Chapman, S; Clements, D L; Conselice, C; Danielson, A L R; Eales, S; Edge, A C; Gibb, A; Hughes, D; Jenness, T; Knudsen, K K; Lacey, C; Marsden, G; McMahon, R; Oliver, S; Page, M J; Peacock, J A; Rigopoulou, D; Robson, E I; Spaans, M; Stevens, J; Webb, T M A; Willott, C; Wilson, C D; Zemcov, M

    2012-01-01

    The first deep blank-field 450um map (1-sigma~1.3mJy) from the SCUBA-2 Cosmology Legacy Survey (S2CLS), conducted with the James Clerk Maxwell Telescope (JCMT) is presented. Our map covers 140 arcmin^2 of the COSMOS field, in the footprint of the HST CANDELS area. Using 60 submillimetre galaxies (SMGs) detected at >3.75-sigma, we evaluate the number counts of 450um-selected galaxies with flux densities S_450>5mJy. The 8-arcsec JCMT beam and high sensitivity of SCUBA-2 now make it possible to directly resolve a larger fraction of the cosmic infrared background (CIB, peaking at ~200um) into the individual galaxies responsible for its emission than has previously been possible at this wavelength. At S_450>5mJy we resolve (7.4[+/-]0.7)x10^-2 MJy/sr of the CIB at 450um (equivalent to 16[+/-]7% of the absolute brightness measured by COBE at this wavelength) into point sources. A further ~40% of the CIB can be recovered through a statistical stack of 24um emitters in this field, indicating that the majority (~60%) o...

  6. Wake flow behind two side-by-side square cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Yen, Shun C., E-mail: scyen@mail.ntou.edu.t [Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung 202, Taiwan (China); Liu, Jung H. [Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung 202, Taiwan (China)

    2011-02-15

    This study investigates the flow structures, form drag coefficients and vortex-shedding characteristics behind a single-square cylinder and two side-by-side cylinders in an open-loop wind tunnel. The Reynolds number (Re) and gap ratio (g*) are 2262 < Re < 28,000 and 0 {<=} g* {<=} 12, respectively. The flow patterns around the square cylinders are determined using the smoke-wire scheme. Experimental results indicate that the flow structures behind two side-by-side square cylinders are classified into three modes -single mode, gap-flow mode and couple vortex-shedding. The gap-flow mode displays anti-phase vortex shedding induced from the interference between the two square cylinders. However, the couple vortex-shedding mode exhibits in-phase vortex shedding that is caused by the independent flow behavior behind each square cylinder. The surface-pressure profile, form drag coefficient for each square cylinder (C{sub D}-bar) and vortex-shedding frequency were measured and calculated using a pressure transducer and a hot-wire anemometer. For two side-by-side cylinder configurations, the maximum C{sub D}-bar of 2.24 occurs in the single mode, while the minimum C{sub D}-bar of 1.68 occurs in the gap-flow mode. Additionally, the C{sub D}-bar in the coupled vortex-shedding mode is intermediate and approximately equal to that of a single (isolated) square cylinder. Moreover, the single mode has the highest Strouhal number (St) and the gap-flow mode has the lowest St.

  7. Adaptive individual-cylinder thermal state control using intake air heating for a GDCI engine

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Gregory T.; Sellnau, Mark C.

    2016-08-09

    A system for a multi-cylinder compression ignition engine includes a plurality of heaters, at least one heater per cylinder, with each heater configured to heat air introduced into a cylinder. Independent control of the heaters is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the heater for that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder compression ignition engine, including determining a combustion parameter for combustion taking place in a cylinder of the engine and controlling a heater configured to heat air introduced into that cylinder, is also provided.

  8. The Interaction Vortex Flow Around Two Bluff Cylinders

    OpenAIRE

    Hirao K.; Yokoi Y.

    2013-01-01

    In this study, the interaction vortex flow features around a pair of parallel arranged bluff cylinders were observed by visualizing water flow experiment at the range of the gap ratio G/d=0~3. It was obtained that the result of established wind tunnel test and the result of this water tank test agreed about the characteristics of vortex shedding when varying the distance of circular cylinder gap. The flow pattern and vortex shedding frequency of another type bluff cylinder (triangular and squ...

  9. Characteristics of Electrorheological Fluid Flow Between Two Concentric Cylinders

    Institute of Scientific and Technical Information of China (English)

    PENG Jie; ZHU Ke-Qin; XI Bao-Shu

    2000-01-01

    The characteristics of Couette flow of electrorheological fluid (ERF) between concentric cylinders is dependent on the parameter β, which is in the yield stress formula of ERF. In the case of β > 2, the yield region locates between the yield surface and the outer cylinder. In the case of β < 2, the yield region locates between the yield surface and the inner cylinder. When β=2, there is no yield surface. Steady and time dependent numerical results in relation to different β are presented and discussed.

  10. Numerical simulation of VAWT on the effects of rotation cylinder

    Science.gov (United States)

    Xing, Shuda; Cao, Yang; Ren, Fuji

    2017-06-01

    Based on Finite Element Analysis Method, studying on Vertical Axis Wind Turbine (VAWT) which is added rotating cylinder in front of its air foils, especially focusing on the analysis of NACA6 series air foils about variation of lift to drag ratio. Choosing the most suitable blades with rotary cylinder added on leading edge. Analysis indicates that the front rotating cylinders on the VAWT is benefit to lift rise and drag fall. The most suitable air foil whose design lift coefficient is 0.8, the blades relative thickness is 20%, and the optimistic tip speed ratio is about 7.

  11. Viscous Swirling Flow over a Stretching Cylinder

    Institute of Scientific and Technical Information of China (English)

    Tiegang FANG; ShanshanYAO

    2011-01-01

    We investigate a viscous How over a cylinder with stretching and torsional motion. There is an exact solution to the Navier-Stokes equations and there exists a unique solution for all the given values of the flow Reynolds number. The results show that velocity decays faster for a higher Reynolds number and the How penetrates shallower into the ambient Huid. All the velocity proHles decay algebraically to the ambient zero velocity.%We investigate a viscous flow over a cylinder with stretching and torsional motion.There is an exact solution to the Navier-Stokes equations and there exists a unique solution for all the given values of the flow Reynolds number.The results show that velocity decays faster for a higher Reynolds number and the flow penetrates shallower into the ambient fluid.All the velocity profiles decay algebraically to the ambient zero velocity.Exact solutions of the Navier-Stokes (NS) equations play important roles in the development of fluid mechanics.In the review articles,[1,2] Wang summarized the available exact solutions of the unsteady state and of the steady-state NS equations.Swirl flows have important engineering applications in many fields such as the cyclone for separation of solid,liquid and gas,swirl atomizers,swirl combustion devices,heat transfer enhancement and others.[3,4] A famous example of flows involving rotation or swirl is the rotating disk problem studied by von Karman.[5-8] The flow induced by a stretching boundary is also important in the extrusion processes in plastic and metal industries.[9-11] Crane[12] presented an exact solution of the two-dimensional NS equations for a stretching sheet problem with a closed analytical form.The stretching wall problem was extended by Wang[13]to a three-dimensional setting.The flow between two stretching disks was studied by Fang and Zhang recently.[14] The combined effects of disk stretching and rotation on the von Karman flow was investigated by Fang.[15] The flow inside a channel or a

  12. Reluctance Machine for a Hollow Cylinder Flywheel

    Directory of Open Access Journals (Sweden)

    Magnus Hedlund

    2017-03-01

    Full Text Available A hollow cylinder flywheel rotor with a novel outer rotor switched reluctance machine (SRM mounted on the interior rim is presented, with measurements, numerical analysis and analytical models. Practical experiences from the construction process are also discussed. The flywheel rotor does not have a shaft and spokes and is predicted to store 181 Wh / kg at ultimate tensile strength (UTS according to simulations. The novel SRM is an axial flux machine, chosen due to its robustness and tolerance for high strain. The computed maximum tip speed of the motor at UTS is 1050 m / s . A small-scale proof-of-concept electric machine prototype has been constructed, and the machine inductance has been estimated from measurements of voltage and current and compared against results from analytical models and finite element analysis (FEA. The prototype measurements were used to simulate operation during maximal speed for a comparison towards other high-speed electric machines, in terms of tip speed and power. The mechanical design of the flywheel was performed with an analytical formulation assuming planar stress in concentric shells of orthotropic (unidirectionally circumferentially wound carbon composites. The analytical approach was verified with 3D FEA in terms of stress and strain.

  13. Cylinder Block Fixture for Mistake Proofing.

    Directory of Open Access Journals (Sweden)

    L.B.Raut

    2014-10-01

    Full Text Available The project idea basically developed from trunnion tables which are one type of fixture having ability to rotate about its axis and able to fix the component at any angle, so there is no requirement of angle plate and sine plates, drilling process is also computer controlled so no guide bush is required, So robust design for extra rigidity, flexibility and simple to use. In this project task is difficult as design rotary cage type fixture for component like cylinder block, which is heavy of 76 kg. it is not possible to rotate or handle component manually and proceed on them to make this process accident proof and automated for this purpose we are designing a rotary cage which rotate 360 degree and allow indexing to process on the component. Processes are to be operated on the component are drilling tapping and air blow washing ,Since drilling don’t need clamping here components self weight will enough to carry drilling force and tapping force coming through power tools. Therefore, rotary cage type fixture is critical importance.

  14. Flow past rotating and stationary circular cylinders near a plane screen. II - Characteristics of flow past a stationary cylinder

    Science.gov (United States)

    Kovalenko, V. M.; Byehkov, N. M.; Kisel, G. A.; Dikovskaia, N. D.

    1984-03-01

    Measurements have been made of pressure distributions and pulsations in a cross flow past a circular cylinder placed near a plane screen of finite length. The experiments reported here have been carried out under low turbulence conditions over a range of Reynolds numbers that includes the critical values. The boundary layer separation points and the evolution of the front critical point and other characteristic zones with the distance to the screen are determined. The components of the aerodynamic force acting on the cylinder and the Strouhal number are calculated on the basis of the predominant pulsation frequencies on the cylinder.

  15. Erosion patterns on a granular bed around a vertical cylinder

    Directory of Open Access Journals (Sweden)

    Lachaussée Florent

    2017-01-01

    Full Text Available We report on two different patterns that can be observed at the bed surface close to a vertical cylinder when submitted to a strong enough steady water flow. The classical scour pattern observed at the cylinder foot and due to the “horseshoe” vortex around occurs at a critical velocity Uc1 below the critical velocity Uc0 for erosion without any cylinder, thus under clear-water conditions. But we observe also another pattern downstream the cylinder which consists of two symmetrical ovoid holes that look like “bunny ears”. This new scour pattern referred as BES can be observed at lower velocities that the horseshoe scour (HSS, above a critical velocity Uc2 < Uc1 , with a timescale formation much higher that the one of HSS.

  16. Controlling a negative loaded hydraulic cylinder using pressure feedback

    DEFF Research Database (Denmark)

    Hansen, M.R.; Andersen, T.O.

    2010-01-01

    the high pass filtered pressure gradient equal tozero is introduced. It yields lead compensation with a markedly improved performance. The sizing of the filter is described taking into account the bandwidth of the directional control valve. The suggested control scheme is implemented and examined......This paper is concerned with the inherent oscillatory nature of pressure compensated velocity control of a hydraulic cylinder subjected to a negative load and suspended by means of an over-center valve. Initially, a linearized stability analysis of such a hydraulic circuit is carried out clearly...... showing that without extra measures such a system will be unstable in a substantial part of the cylinder stroke. The stability criterion is expressed in hard quantities: Cylinder volumes, cylinder area ratio and overcenter valve pilot area ratio. A pressure feed back scheme that has as target to maintain...

  17. Wave propagation in coated cylinders with reference to fretting fatigue

    Indian Academy of Sciences (India)

    M Ramesh; Satish V Kailas; K R Y Simha

    2008-06-01

    Fretting fatigue is the phenomenon of crack initiation due to dynamic contact loading, a situation which is commonly encountered in mechanical couplings subjected to vibration. The study of fretting fatigue in high frequency regime has gained importance in recent years. However the stress wave effects at high frequency y loading is scanty in the literature. The objective of present investigation is to study stress wave propagation in cylinders with reference to high frequency fretting. The case of a coated cylinder is considered since coating is often provided to improve tribological properties of the component. Rule of mixtures is proposed to understand the dispersion phenomenon in coated or layered cylinder knowing the dispersion relation for the cases of homogeneous cylinders made of coating and substrate materials separately. The possibility of stress wave propagation at the interface with a particular phase velocity without dispersion is also discussed. Results are given for two different thicknesses of coating.

  18. Grinding efficiency improvement of hydraulic cylinders parts for mining equipment

    National Research Council Canada - National Science Library

    Aleksandr Korotkov; Vitaliy Korotkov; Leonid Mametyev; Lidia Korotkova; Tatiana Terjaeva

    2017-01-01

    The aim of the article is to find out ways to improve parts treatment and components of mining equipment on the example of hydraulic cylinders parts, used as pillars for mine roof supports, and other actuator mechanisms...

  19. Motion by Volume Preserving Mean Curvature Flow Near Cylinders

    CERN Document Server

    Hartley, David

    2012-01-01

    Center manifold analysis can be used in order to investigate the stability of the stationary solutions of various PDEs. This can be done by considering the PDE as an ODE between certain Banach spaces and linearising about the stationary solution. Here we investigate the volume preserving mean curvature flow using such a technique. We will consider surfaces with boundary contained within two parallel planes such that the surface meets these planes orthogonally. With this set up the stationary solution is a cylinder. We will find that for initial surfaces that are sufficiently close to a cylinder the flow will exist for all time and converge to a cylinder exponentially. In particular, we show that there exists global solutions to the flow that converge to a cylinder, which are initially non-axially symmetric. A similar case where the initial surfaces are compact without boundary has previously been investigated by Escher and Simonett (1998).

  20. Theoretical investigation of noise transmission into a finite cylinder

    Science.gov (United States)

    Li, Deyu; Vipperman, Jeffrey S.

    2004-05-01

    A new mathematical model for characterizing noise transmission into a finite elastic cylindrical structure with application to a ChamberCore composite cylinder is presented. A plane wave obliquely impinges on the structure, the external sound field is approximated by the solution for an infinite cylinder, and the internal sound field is solved with the structural and acoustic modal interaction method. The noise reduction spectrum for characterizing noise transmission into the cylinder is defined, and the analytical model for the calculation of the noise reduction spectrum is developed. The analytical results show that the cavity resonances dominate the noise transmission into the finite cylinder, and the longitudinal acoustic modes play an important role in the noise transmission at the low frequencies. These results are matched with experimental results.

  1. NONLINEAR FREE SURFACE ACTION WITH AN ARRAY OF VERTICAL CYLINDERS

    Institute of Scientific and Technical Information of China (English)

    HUANG J. B.

    2004-01-01

    Nonlinear diffraction of regular waves by an array of bottom-seated circular cylinders is investigated in frequency domain, based on a Stokes expansion approach. A complete semi-analytical solution is developed which allows an efficient evaluation of the second-order potentials in the entire fluid domain, and the wave forces on the structure. Expressions are derived for the second-order potential in the vicinity of individual cylinders. These expressions have a simple form, thus providing an effective means for investigating the wave enhancement due to nonlinear interactions with multiple cylinders. Based on the present method, the wave run-up and free-surface elevations around an array of two, three and four cylinders are investigated numerically.

  2. Prediction of External Corrosion for Steel Cylinders 2003 Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmoyer, RLS

    2003-09-24

    Depleted uranium hexafluoride (UF{sub 6}) is stored in over 60,000 steel cylinders at the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee, at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and at the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The cylinders range in age from six to 52 years. Although when new the cylinders had wall thicknesses specified to within manufacturing tolerances, over the years corrosion has reduced their actual wall thicknesses. The UF{sub 6} Cylinder Project is managed by the United States Department of Energy (DOE) to safely maintain the UF{sub 6} and the cylinders containing it. The requirements of the Project are delineated in the System Requirements Document (LMES 1997a), and the actions needed to fulfill those requirements are specified in the System Engineering Management Plan (LMES 1997b). This report documents activities that address requirements and actions involving forecasting cylinder wall thicknesses. Wall thickness forecasts are based on models fit to ultrasonic thickness (UT) measurement data. First, UT data collected during FY02 is combined with UT data collected in earlier years (FY92-FY01), and all of the data is inventoried chronologically and by various subpopulations. Next, the data is used to model either maximum pit depth or minimum thickness as a function of cylinder age, subpopulation (e.g., PGDP G-yard, bottom-row cylinders), and initial thickness estimates. The fitted models are then used to extrapolate minimum thickness estimates into the future and to compute estimates of numbers of cylinders expected to fail various thickness criteria. A model evaluation is performed comparing UT measurements made in FY02 with model-fitted projections based only on data collected before FY02. The FY02 UT data, entered into the corrosion model database and not available for the previous edition of this report (Schmoyer and Lyon 2002), consists of thickness measurements of 48

  3. On the flow in an annulus surrounding a whirling cylinder

    Science.gov (United States)

    Brennen, C.

    1976-01-01

    When fluid in an annulus between two cylinders is set in motion by whirling movements of one or both of the cylinders, dynamic forces are imposed by the fluid on the cylinders. Knowledge of these forces is frequently important, indeed often critical, to the engineer designing rotor systems or journal bearings. Quite general solutions of the Navier-Stokes equations are presented for this problem and are limited only by restrictions on the amplitude of the whirl motion. From these solutions, the forces are derived under a wide variety of circumstances, including large and small annular widths, high and low Reynolds numbers, and the presence and absence of a mean flow created by additional net rotation of one or both of the cylinders.

  4. LOW VELOCITY INDICATOR USING SHED VORTICITY FREQUENCY OF CYLINDER.

    Science.gov (United States)

    of accurately determining the velocity of a fluid and its rate of change . Static pressure variations across the top and bottom of the cylinder...instrument is highly feasible for determining velocity and its rate of change . (Author)

  5. 49 CFR 178.38 - Specification 3B seamless steel cylinders.

    Science.gov (United States)

    2010-10-01

    ... cylinders welded or formed by spinning is, under no condition, to be less than two times the minimum wall...-pressure parts, and only to the tops and bottoms of cylinders having a service pressure of 500 psig or less... wall thickness. (m) Leakage test. All spun cylinders and plugged cylinders must be tested for leakage...

  6. Effect of Backpacking and Internal Pressurization on Stresses Transmitted to Buried Cylinders.

    Science.gov (United States)

    Various aspects of the behavior of buried cylinders associated with backpacking , internal pressurization, and slippage at the interface are...considered. Parametric curves are presented for horizontally and vertically buried cylinders with and without backpacking . Four configurations of statically...loaded, horizontally buried cylinders were considered: no backpacking , rectangular backpacking placed above the cylinder, backpacking placed around

  7. Two-Fluid Couette Flow between Concentric Cylinders.

    Science.gov (United States)

    1984-01-01

    CONCENTRIC CYLINDERS Yuriko Renardy and Daniel D. Joseph* Technical Summary Report #2622 January 1984 ABSTRACT -1W considers,he flow of two immiscible...CYLINDERS Yuriko Renardy and Daniel D. Joseph* Introduction We consider linear stability of the flow of two immiscible fluids separated by an interface...AUTiOR(,) 8. CONTRACT OR GRANT NUMBER(@) Yuriko Renardy and Daniel D. Joseph DAAGZ9-80-C-0041 11. PERFORMING ORGANIZATION NAME AND ADDRESS 10

  8. ROBUST CYLINDER FITTING IN THREE-DIMENSIONAL POINT CLOUD DATA

    Directory of Open Access Journals (Sweden)

    A. Nurunnabi

    2017-05-01

    Full Text Available This paper investigates the problems of cylinder fitting in laser scanning three-dimensional Point Cloud Data (PCD. Most existing methods require full cylinder data, do not study the presence of outliers, and are not statistically robust. But especially mobile laser scanning often has incomplete data, as street poles for example are only scanned from the road. Moreover, existence of outliers is common. Outliers may occur as random or systematic errors, and may be scattered and/or clustered. In this paper, we present a statistically robust cylinder fitting algorithm for PCD that combines Robust Principal Component Analysis (RPCA with robust regression. Robust principal components as obtained by RPCA allow estimating cylinder directions more accurately, and an existing efficient circle fitting algorithm following robust regression principles, properly fit cylinder. We demonstrate the performance of the proposed method on artificial and real PCD. Results show that the proposed method provides more accurate and robust results: (i in the presence of noise and high percentage of outliers, (ii for incomplete as well as complete data, (iii for small and large number of points, and (iv for different sizes of radius. On 1000 simulated quarter cylinders of 1m radius with 10% outliers a PCA based method fit cylinders with a radius of on average 3.63 meter (m; the proposed method on the other hand fit cylinders of on average 1.02 m radius. The algorithm has potential in applications such as fitting cylindrical (e.g., light and traffic poles, diameter at breast height estimation for trees, and building and bridge information modelling.

  9. MATHEMATICAL METHODS TO DETERMINE THE INTERSECTION CURVES OF THE CYLINDERS

    Directory of Open Access Journals (Sweden)

    POPA Carmen

    2010-07-01

    Full Text Available The aim of this paper is to establish the intersection curves between cylinders, by using the Mathematica program. This thing can be obtained by introducing the curves equations, which are inferred, in Mathematica program. This paper take into discussion three right cylinders and another inclined to 45 degrees. The intersection curves can also be obtained by using the classical methods of the descriptive geometry.

  10. Mathematic modelling of circular cylinder deformation under inner grouwth

    Directory of Open Access Journals (Sweden)

    A. V. Siasiev

    2009-09-01

    Full Text Available A task on the intensive deformed state (IDS of a viscoelastic declivous cylinder, which is grown under the action of inner pressure, is considered. The process of continuous increase takes a place on an internal radius so, that a radius and pressure change on set to the given law. The special case of linear law of creeping is considered, and also numeral results are presented as the graphs of temporal dependence of tensions and moving for different points of cylinder.

  11. Mechanisms of active control for noise inside a vibrating cylinder

    Science.gov (United States)

    Lester, Harold C.; Fuller, Chris R.

    1987-01-01

    The active control of propeller-induced noise fields inside a flexible cylinder is studied with attention given to the noise reduction mechanisms inherent in the present coupled acoustic shell model. The active noise control model consists of an infinitely long aluminum cylinder with a radius of 0.4 m and a thickness of 0.001 m. Pressure maps are shown when the two external sources are driven in-phase at a frequency corresponding to Omega = 0.22.

  12. Radiation dose rates from UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Friend, P.J. [Urenco, Capenhurst (United Kingdom)

    1991-12-31

    This paper describes the results of many studies, both theoretical and experimental, which have been carried out by Urenco over the last 15 years into radiation dose rates from uranium hexafluoride (UF{sub 6}) cylinders. The contents of the cylinder, its history, and the geometry all affect the radiation dose rate. These factors are all examined in detail. Actual and predicted dose rates are compared with levels permitted by IAEA transport regulations.

  13. Vertical force acting on partly submerged spindly cylinders

    Directory of Open Access Journals (Sweden)

    Xinbin Zhang

    2014-04-01

    Full Text Available When an object is placed on a water surface, the air-water interface deforms and a meniscus arises due to surface tension effects, which in turn produces a lift force or drag force on the partly submerged object. This study aims to investigate the underlying mechanism of the vertical force acting on spindly cylinders in contact with a water surface. A simplified 2-D model is presented, and the profile of the curved air-water interface and the vertical force are computed using a numerical method. A parametric study is performed to determine the effects of the cylinder center distance, inclined angle, static contact angle, and radius on the vertical force. Several key conclusions are derived from the study: (1 Although the lift force increases with the cylinder center distance, cylinders with smaller center distances can penetrate deeper below the water surface before sinking, thereby obtaining a larger maximum lift force; (2 An increase in the inclined angle reduces the lift force, which can enable the lower cylinders fall more deeply before sinking; (3 While the effect of static contact angle is limited for angles greater than 90°, hydrophobicity allows cylinders to obtain a larger lift force and load capacity on water; (4 The lift force increases rapidly with cylinder radius, but an increase in radius also increases the overall size and weight of cylinders and decreases the proportion of the surface tension force. These findings may prove helpful in the design of supporting legs of biologically-inspired miniature aquatic devices, such as water strider robots.

  14. Primary instabilities and bicriticality in fiber suspensions between rotating cylinders

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The linear stability of fiber suspensions between two concentric cylinders rotating independently is studied. The modified stability equation is obtained based on the fiber orientation model and Hinch-Leal closure approximation. The primary instabilities and bicritical curves have been calculated numerically. The critical Reynolds number, wavenumber and wave speeds of fiber suspensions as functions of the aspect ratio, volume concentration of the fibers and the gap width of cylinders are obtained.

  15. Simulation of Flow Around Cylinder Actuated by DBD Plasma

    Science.gov (United States)

    Wang, Yuling; Gao, Chao; Wu, Bin; Hu, Xu

    2016-07-01

    The electric-static body force model is obtained by solving Maxwell's electromagnetic equations. Based on the electro-static model, numerical modeling of flow around a cylinder with a dielectric barrier discharge (DBD) plasma effect is also presented. The flow streamlines between the numerical simulation and the particle image velocimetry (PIV) experiment are consistent. According to the numerical simulation, DBD plasma can reduce the drag coefficient and change the vortex shedding frequencies of flow around the cylinder.

  16. Cylinder expansion test and gas gun experiment comparison

    Energy Technology Data Exchange (ETDEWEB)

    Harrier, Danielle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-30

    This is a summer internship presentation by the Hydro Working Group at Los Alamos National Laboratory (LANL) and goes into detail about their cylinder expansion test and gas gun experiment comparison. Specifically, the gas gun experiment is detailed along with applications, the cylinder expansion test is detailed along with applications, there is a comparison of the methods with pros and cons and limitations listed, the summer project is detailed, and future work is talked about.

  17. Negative refractive index metamaterials from inherently non-magnetic materials for deep infrared to terahertz frequency ranges.

    Science.gov (United States)

    Yannopapas, Vassilios; Moroz, Alexander

    2005-06-29

    We present a new set of artificial structures which can exhibit a negative refractive index band in excess of 6% in a broad frequency range from the deep infrared to the terahertz region. The structures are composites of two different kinds of non-overlapping spheres, one made from inherently non-magnetic polaritonic and the other from a Drude-like material. The polaritonic spheres are responsible for the existence of negative effective magnetic permeability whilst the Drude-like spheres are responsible for negative effective electric permittivity. The resulting negative refractive index structures are truly subwavelength structures with wavelength-to-structure ratio 14:1, which is almost 50% higher than has been previously achieved. Our results are explained in the context of the extended Maxwell-Garnett theory and are reproduced by calculations based on the layer Korringa-Kohn-Rostoker method, an ab initio multiple scattering theory. The role of absorption in the constituent materials is discussed. Effective medium computer F77 code is freely available at http://www.wave-scattering.com.

  18. Comparison of the enrollment percentages of magnet and non-magnet schools in a large urban school district.

    Directory of Open Access Journals (Sweden)

    Emily Arcia

    2006-12-01

    Full Text Available Are magnet schools in a position to meet diversity ideals? As districts are declared unitary and released from court ordered desegregation, many are framing their commitments to fairness and equity in terms of diversity˜i.e., comparable rates of participation and comparable educational outcomes in all segments the student population. In this study, the enrollment statistics for magnet and contiguous non-magnet public schools in Miami-Dade County Public Schools, a large, urban district that had been released from court ordered desegregation, were compared to each other and to district enrollment averages at two time points: the year the district was declared unitary and four years hence. Findings indicated that within four years of being declared unitary, the gains that the magnet schools had made with regards to Black/non-Black desegregation had eroded substantially. Also, in the four year span, magnet schools had not made significant strides in meeting the diversity ideals adopted by the district at being released from supervision by the court. These findings highlight the difficulty of attaining diversity in student enrollment characteristics when quotas are not used and suggest that recruitment and enrollment policies must be crafted with care if districts are to achieve diversity goals.

  19. A photometric study of chemically peculiar stars with the STEREO satellites. II. Non-magnetic chemically peculiar stars

    CERN Document Server

    Paunzen, E; Fossati, L; Netopil, M; White, G J; Bewsher, D

    2012-01-01

    We have analysed the photometric data obtained with the STEREO spacecraft for 558 non-magnetic chemically peculiar (CP) stars to search for rotational and pulsational variability. Applying the Lomb-Scargle and the phase dispersion minimisation methods, we have detected photometric variability for 44 objects from which 35 were previously unknown. The new objects are all bright stars on the Ecliptic Plane (magnitude range 4.7 < V < 11.7) and will therefore be of great interest to studies of stellar structure and evolution. In particular, several show multiple signals consistent with hybrid delta Scuti and gamma Doradus pulsation, with different periodicities allowing very different regions of the stellar interior to be studied. There are two subgroups of stars in our sample: the cool metallic line Am (CP1) and the hot HgMn (CP3) stars. These objects fall well inside the classical instability strip where delta Scuti, gamma Doradus and slowly pulsating B-type stars are located. We also expect to find period...

  20. Flow induced vibrations in arrays of irregularly spaced cylinders

    Science.gov (United States)

    Taub, Gordon; Michelin, Sébastien

    2014-11-01

    Historically the main industrial applications of cylinder arrays in cross flows favored regular arrangements of cylinders. For this reason, most past studies of Flow Induced Vibrations (FIV) in large cylinder arrays have focused on such arrangements. Recently there has been some interest in generating renewable energy using FIV of bluff bodies. In such applications it will likely be beneficial to enhance, rather than suppress FIV. It is not known a priori if regular or irregularly spaced arrays are most adequate for this type of application. In this study, wind tunnel experiments were conducted on one regularly spaced array and four different irregularly spaced arrays of cylinders in a cross flow. Each arrangement of cylinders was examined under eight different orientations to a cross flow ranging between 10 m/s and 17 m/s. The average amplitude of vibration of the cylinders was found to highly depend on arrangement and orientation. The typical amplitude of vibration of the rods in the irregular arrangements were found to be an order of magnitude larger than that of the regular array. A simple model was proposed in order to predict if a given arrangement was likely to produce large oscillations, and the validity of the model was examined. This research was supported by a Marie Curie International Reintegration Grant within the 7th European Community Framework Program (Grant PIRG08-GA-2010-276762).

  1. Wave Run-up on A Coaxial Perforated Circular Cylinder

    Institute of Scientific and Technical Information of China (English)

    ZHU Da-tong

    2011-01-01

    This paper describes a plane regular wave interaction with a combined cylinder which consists of a solid inner column and a coaxial perforated outer cylinder. The outer perforated surface is a thin porous cylinder with an annular gap between it and the inner cylinder. The non-linear boundary condition at the perforated wall is a prime focus in the study;energy dissipation at the perforated wall occurs through the resistance to the fluid across the perforated wall. Explicit analytical formulae are presented to calculate the wave run-up on the outer and inner surfaces of the perforated cylinderand the surface of the inner column. The theoretical results of the wave run-up are compared with previous experimental data. Numerical results have also been obtained: when the ratio of the annular gap between the two cylinders to incidentwavelength (b-a)/L≤0.1, the wave run-up on the inner surface of the perforated cylinder and the surface of inner column can partially or completely exceed the incident wave height.

  2. Kinematics investigations of cylinders rolling down a ramp using tracker

    Science.gov (United States)

    Prima, Eka Cahya; Mawaddah, Menurseto; Winarno, Nanang; Sriwulan, Wiwin

    2016-02-01

    Nowadays, students' exploration as well as students' interaction in the application stage of learning cycle can be improved by directly model real-world objects based on Newton's Law using Open Source Physics (OSP) computer-modeling tools. In a case of studying an object rolling down a ramp, a traditional experiment method commonly uses a ticker tape sliding through a ticker timer. However, some kinematics parameters such as the instantaneous acceleration and the instantaneous speed of object cannot be investigated directly. By using the Tracker video analysis method, all kinematics parameters of cylinders rolling down a ramp can be investigated by direct visual inspection. The result shows that (1) there are no relations of cylinders' mass as well as cylinders' radius towards their kinetics parameters. (2) Excluding acceleration data, the speed and position as function of time follow the theory. (3) The acceleration data are in the random order, but their trend-lines closely fit the theory with 0.15% error. (4) The decrease of acceleration implicitly occurs due to the air friction acting on the cylinder during rolling down. (5) The cylinder's inertial moment constant has been obtained experimentally with 3.00% error. (6) The ramp angle linearly influences the cylinders' acceleration with 2.36% error. This research implied that the program can be further applied to physics educational purposes.

  3. A characteristic analysis of the fluidic muscle cylinder

    Science.gov (United States)

    Kim, Dong-Soo; Bae, Sang-Kyu; Hong, Sung-In

    2005-12-01

    The fluidic muscle cylinder consists of an air bellows tube, flanges and lock nuts. It's features are softness of material and motion, simplicity of structure, low production cost and high power efficiency. Recently, unlikely the pneumatic cylinder, the fluidic muscle cylinder without air leakage, stick slip, friction, and seal was developed as a new concept actuator. It has the characteristics such as light weight, low price, high response, durable design, long life, high power, high contraction, which is innovative product fulfilling RT(Robot Technology) which is one of the nation-leading next generation strategy technologies 6T as well as cleanness technology. The application fields of the fluidic muscle cylinder are so various like fatigue tester, brake, accelerator, high technology testing device such as driving simulator, precise position, velocity, intelligent servo actuator under special environment such as load controlling system, and intelligent robot. In this study, we carried out the finite element modeling and analysis about the main design variables such as contraction ration and force, diameter increment of fluidic muscle cylinder. On the basis of finite element analysis, the prototype of fluidic muscle cylinder was manufactured and tested. Finally, we compared the results between the test and the finite element analysis.

  4. Characteristic analysis and experimental evaluation of artificial pneumatic cylinder

    Science.gov (United States)

    Kim, Dong-Soo; Bae, Sang-Kyu; Choi, Kyung-Hyun

    2005-12-01

    The fluidic muscle cylinder consists of an air bellows tube, flanges and lock nuts. Its features are softness of material and motion, simplicity of structure, low production cost and high power efficiency. Recently, unlikely the pneumatic cylinder, the fluidic muscle cylinder without air leakage, stick slip, friction, and seal was developed as a new concept actuator. It has the characteristics such as light weight, low price, high response, durable design, long life, high power, high contraction, which is innovative product fulfilling RT(Robot Technology) which is one of the nation-leading next generation strategy technologies 6T as well as cleanness technology. The application fields of the fluidic muscle cylinder are so various like fatigue tester, brake, accelerator, high technology testing device such as driving simulator, precise position, velocity, intelligent servo actuator under special environment such as load controlling system, and intelligent robot. In this study, we carried out the finite element modeling and analysis about the main design variables such as contraction ration and force, diameter increment of fluidic muscle cylinder. On the basis of finite element analysis, the prototype of fluidic muscle cylinder was fabricated and tested. Finally, we compared the results between the test and the finite element analysis.

  5. Laminar vortex shedding behind a cooled circular cylinder

    Science.gov (United States)

    Trávníček, Zdeněk; Wang, An-Bang; Tu, Wen-Yun

    2014-02-01

    This paper addresses the functional demonstration of a hot air flow generator driven by convective heat transfer and the airflow behind a cooled circular cylinder in cross flow in the low velocity range. The wake flow was investigated experimentally using flow visualization, hot-wire anemometry, and laser Doppler anemometry. An evaluation of the free-stream velocity from the vortex shedding frequency was derived for the isothermal and non-isothermal cases and demonstrated using simple stroboscope measurements. The results confirm that cylinder cooling destabilizes the wake flow in air, i.e., the laminar steady regime can be changed into the vortex shedding regime, and the vortex shedding frequency increases as the cylinder temperature decreases. This thermal effect of cylinder cooling is consistent with its counterpart, the known effect of flow stabilization by cylinder heating. The effective temperature and effective Reynolds number concept have been further quantitatively evaluated, and the extension of their validity to the case of cooled cylinders has been confirmed.

  6. The Interaction Vortex Flow Around Two Bluff Cylinders

    Directory of Open Access Journals (Sweden)

    Hirao K.

    2013-04-01

    Full Text Available In this study, the interaction vortex flow features around a pair of parallel arranged bluff cylinders were observed by visualizing water flow experiment at the range of the gap ratio G/d=0~3. It was obtained that the result of established wind tunnel test and the result of this water tank test agreed about the characteristics of vortex shedding when varying the distance of circular cylinder gap. The flow pattern and vortex shedding frequency of another type bluff cylinder (triangular and square cylinder were also investigated. As a result of the experiment, it was shown that the flow pattern of wake flow was divided into three kinds (coupled vortex streets, biased gap flow and single vortex street regardless of the cylinder section shape and cylinder size. Then, the region of the appearance of flow pattern was shown about each case. In the case where two each other independent vortex streets were formed, three typical flow patterns of vortex formation (in-phase coupled vortex streets, out-of-phase coupled vortex streets and complication coupled vortex streets were observed. It was known that three configuration of vortex formation appear intermittently and alternatively.

  7. Vortex Shedding in the Wake of a Dual Step Cylinder

    CERN Document Server

    Morton, Chris

    2012-01-01

    A dual-step cylinder is comprised of a large diameter cylinder (D) with low aspect ratio (L/D) attached co-axially to the mid-span of a small diameter cylinder (d). The fluid dynamics video presented in this investigation is used to illustrate the effect of aspect ratio on dual step cylinder wake development for Re = 2100, D/d = 2, and 0.2 < L/D < 3. In addition, the video provides visualization of such flow phenomena as interaction of spanwise vortices, development of streamwise vortex filaments, and formation of Kelvin-Helmholtz rollers. The experiments were performed in a water flume at the University of Waterloo. A hydrogen bubble flow visualization technique was employed to visualize vortical structures downstream of each cylinder model. High-resolution images of the flow were obtained with a high speed Photron camera and post-processed using Adobe Photoshop CS4. The results show a plethora of vortices developing in the wake of the dual step cylinder. For 1 < L/D < 3, spanwise vortex shedding...

  8. Regimes of flow induced vibration for tandem, tethered cylinders

    Science.gov (United States)

    Nave, Gary; Stremler, Mark

    2015-11-01

    In the wake of a bluff body, there are a number of dynamic response regimes that exist for a trailing bluff body depending on spacing, structural restoring forces, and the mass-damping parameter m* ζ . For tandem cylinders with low values of m* ζ , two such regimes of motion are Gap Flow Switching and Wake Induced Vibration. In this study, we consider the dynamics of a single degree-of-freedom rigid cylinder in the wake of another in these regimes for a variety of center-to-center cylinder spacings (3-5 diameters) and Reynolds numbers (4,000-11,000). The system consists of a trailing cylinder constrained to a circular arc around a fixed leading cylinder, which, for small angle displacements, bears a close resemblance to the transversely oscillating cylinders found more commonly in existing literature. From experiments on this system, we compare and contrast the dynamic response within these two regimes. Our results show sustained oscillations in the absence of a structural restoring force in all cases, providing experimental support for the wake stiffness assumption, which is based on the mean lift toward the center line of flow.

  9. The Interaction Vortex Flow Around Two Bluff Cylinders

    Science.gov (United States)

    Yokoi, Y.; Hirao, K.

    2013-04-01

    In this study, the interaction vortex flow features around a pair of parallel arranged bluff cylinders were observed by visualizing water flow experiment at the range of the gap ratio G/d=0~3. It was obtained that the result of established wind tunnel test and the result of this water tank test agreed about the characteristics of vortex shedding when varying the distance of circular cylinder gap. The flow pattern and vortex shedding frequency of another type bluff cylinder (triangular and square cylinder) were also investigated. As a result of the experiment, it was shown that the flow pattern of wake flow was divided into three kinds (coupled vortex streets, biased gap flow and single vortex street) regardless of the cylinder section shape and cylinder size. Then, the region of the appearance of flow pattern was shown about each case. In the case where two each other independent vortex streets were formed, three typical flow patterns of vortex formation (in-phase coupled vortex streets, out-of-phase coupled vortex streets and complication coupled vortex streets) were observed. It was known that three configuration of vortex formation appear intermittently and alternatively.

  10. Quantum phase transition in ultra small doubly connected superconducting cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Sternfeld, I. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)], E-mail: itayst@post.tau.ac.il; Koret, R. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Shtrikman, H. [Department of Condensed Matter, Weizmann Institute of Science, Rehovot 76100 (Israel); Tsukernik, A. [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv 69978 (Israel); Karpovski, M.; Palevski, A. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

    2008-02-15

    The kinetic energy of Cooper pairs, in doubly connected superconducting cylinders, is a function of the applied flux and the ratio between the diameter of the cylinder and the zero temperature coherence length d/{xi}(0). If d >{xi}(0) the known Little-Parks oscillations are observed. On the other hand if d <{xi}(0), the superconducting state is energetically not favored around odd multiples of half flux quanta even at T{approx}0, resulting in the so called destructive regime [Y. Liu, et al., Science 294 (2001) 2332]. We developed a novel technique to fabricate superconducting doubly connected nanocylinders with both diameter and thickness less than 100 nm, and performed magnetoresistance measurements on such Nb and Al cylinders. In the Nb cylinders, where d >{xi}(0), we observed the LP oscillations. In the Al cylinders we did not observe a transition to the superconducting state due to the proximity effect, resulted from an Au layer coating the Al. However, we did observe Altshuler-Aronov-Spivak (h/2e) oscillations in these cylinders.

  11. The Jackson Cross-Cylinder. Part 1: Properties

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2007-01-01

    Full Text Available The Jackson cross-cylinder is a lens of fundamental importance in optometry with a key role in the refraction routine.  And yet it appears not to be as well understood as perhaps it should be.  The purpose of this paper is to examine the linear optical character of the Jackson cross-cylinder and, in particular, those properties associated with the operations performed on the lens in the refraction routine, namely flipping and turning.  Corresponding to these operations in physical space are steps in an abstract space, symmetric dioptric power space.  The powers of all Jackson cross-cylinders lie in the plane of antistigmatic powers in the abstract space.  In particular the powers of an F Jackson cross-cylinder (for example, a 0.5-D Jackson cross-cylinder has  5 . 0 = F  D lie on a circle of radius F centred onnull power.  Flipping the lens takes one diametrically across the circle; turning the lens takes one around the circle at twice the rate.  A subsequent paper shows how these operations work in defining the cylinder in the refraction routine.

  12. Supercritical flows past a square cylinder with rounded corners

    Science.gov (United States)

    Cao, Yong; Tamura, Tetsuro

    2017-08-01

    Large-eddy simulations were used to investigate the supercritical aerodynamics of a square cylinder with rounded corners in comparison with those in the subcritical regime. First, the numerical methods, especially the dynamic mixed model, were validated on the basis of their prediction of supercritical flows past a circular cylinder. Then, the supercritical flows past a rounded-corner square cylinder were simulated and systematically clarified. Strong Reynolds number (Re) effects existed in the forces and local pressures as Re increased from o(104) to o(106). Changeover of flow patterns occurred as Re increased. At the supercritical Re, the free stream overall flowed along the cross sections of the cylinder, separated from the leeward corners and generated Karman vortices behind the cylinder. This pattern resulted in a much smaller recirculation region behind the cylinder compared with the subcritical flow. At the micro level, the flow experienced laminar separation and flow reattachment near the frontal corners, followed by the spatial development of turbulent boundary layers (TBLs) on the side faces and turbulent separation near the leeward corners. The feedback by large-scale primary vortex shedding and the small-scale turbulent motions in the high-frequency region with a slope of -5/3 were detected in the TBL. Their interaction affected the spanwise correlations of wall pressure fluctuations. The TBL on the side face differed from the zero-pressure-gradient flat-plate one; it was subjected to pressure gradients varying in space and time.

  13. Flow-induced vibrations of two tandem cylinders in a channel

    Directory of Open Access Journals (Sweden)

    Jiang Ren-Jie

    2012-01-01

    Full Text Available We numerically studied flow-induced vibrations of two tandem cylinders in transverse direction between two parallel walls. The effect of the horizontal separation between two cylinders, ranging from 1.1 to 10, on the motions of the cylinders and the flow structures were investigated and a variety of periodic and non-periodic vibration regimes were observed. The results show that when two cylinders are placed in close proximity to each other, compared with the case of an isolated cylinder, the gap flow plays an important role. As the separation ratio is increased, the fluid-structure interaction decouples and the cylinders behave as two isolated cylinders.

  14. Frictional properties of lubrication greases with the addition of nickel nanoparticles in pneumatic cylinder

    Science.gov (United States)

    Chang, Ho; Lan, Chou-Wei; Guo, Jia-Bin

    2011-12-01

    This paper studies the influence of addition of 100 nm diameter nickel nano-particles on the friction properties of synthetic grease (Li base, VG100) in pneumatic cylinder. The friction force test of pneumatic cylinder equipment measures the frictional force between seal and cylinder bore in pneumatic cylinders. The lubricants with addition of nickel nano-particles were used for lubricating the contact interface between seal and cylinder bore. The friction force test equipment employ a load cell force sensor to measure the friction force between seals and cylinder bores. Results obtained from experimental tests are compared to determine the friction force between seals and cylinder bore in pneumatic cylinders. The study leads to the conclusion that the addition of nickel nano-particles to synthetic grease results in a decrease in friction force between seals and cylinder bores in pneumatic cylinder. This tribological behavior is closely related to the deposition of nano-particles on the rubbing surfaces

  15. Adaptive individual-cylinder thermal state control using piston cooling for a GDCI engine

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Gregory T; Husted, Harry L; Sellnau, Mark C

    2015-04-07

    A system for a multi-cylinder compression ignition engine includes a plurality of nozzles, at least one nozzle per cylinder, with each nozzle configured to spray oil onto the bottom side of a piston of the engine to cool that piston. Independent control of the oil spray from the nozzles is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the oil spray onto the piston in that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder engine, including determining a combustion parameter for combustion taking place in in a cylinder of the engine and controlling an oil spray targeted onto the bottom of a piston disposed in that cylinder is also presented.

  16. Improvement of cylinder block line for high productivity. Koseisansei cylinder block seizo line no kakuritsu

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, M. (Aisin Takaoka Co. Ltd., Tokyo (Japan)); Ito, M. (Toyota Motor Corp., Aichi (Japan))

    1991-05-25

    This paper is a technical report of improvig manufacturing line in an automotive cylinder block casting factory, and enhancing the productivity. Gists of the improvement can be summarized in the following three items: Standardization of the production corresponding to product acceptance condition by the subsequent process; elimination of waste in time by means of establishing production framework, including material handling; and accumulation of small scale automations. The result was the productivity in 1989 increased by 1.2 times that in around 1975 as a result of improved rate of operation, and number of workers reduced to half, supported particularly by manpower saving in core making and finishing processes. For instance, core making machines were given size reduction in the facility and die, and multiple core making function, in which one die makes different cores for the same part. The multiple core making function, which can reduce number of machines necessary to make one cylinder block, has a large advantage not only facilitating arrangemets for small quantity production parts, but also dealing with stepwise capacity increase and eliminating the necessity of keeping spare dies. 16 figs., 1 tab.

  17. Locating Ectopic Foci on a Cylinder

    Science.gov (United States)

    Kuklik, Pawel; Zebrowski, Jan J.

    2003-07-01

    Arrhythmia is a condition in which an additional ectopic pacemaker is present in the tissue of the heart. Localization of ectopic foci is essential for successful radio-frequency ablation, an important surgical way of treating arrhythmia. In one of the possible mechanisms, arrhythmia induced by an ectopic foci located in one of the main blood vessels leading out or onto the heart. The therapeutic procedure in this case is usually ablation of the whole junction of the blood vessel with heart wall. In this way, whatever excitation occurs inside the vessel, it cannot penetrate the ventricles perturbing their contraction cycle. Such an ablation procedure is long and burdened with the risk of the perforation. A more safe method would involve the localization of the source of the excitation (i.e. the ectopic foci) and its ablation. The methods used in cardiology at present involve complicated localization systems and are time-consuming with the patient spending a long time on the operating table. Recently, Hall and Glass have developed numerical methods which allow to quickly to model the localization of the ectopic foci in a flat, square sample of an inhomogeneous medium. Here, we demonstrate an extension of this model for the case of a cylinder containing an ectopic foci, that can be a model of a blood vessel with the source of the ectopic beat inside it. Three methods of localization are implemented. Standard electrodes containing several active tips are used to stimulate the medium locally and locate the foci judging from the reaction of the system. The first one uses electrode activation times to compute the location of the ectopic site. The second one localizes it by measuring the resetting response of the foci, and the third one, uses wavefront curvature. Specifically for the cylindrical geometry of the blood vessel, we developed a localization procedure that allows to quickly localize the pacemaker.

  18. Experimental investigation of the interaction of two cylinders in the flow pattern

    Directory of Open Access Journals (Sweden)

    Vitkovičová Rut

    2015-01-01

    Full Text Available This article discusses the behaviour and interaction of two circular cylinders in the flow pattern when one of the cylinders affects wake of the second cylinder. The wake behind the cylinder was investigated experimentally by using a time resolved PIV and CTA method. Velocity fields were obtained for several regimes of Reynolds numbers and several positions of the second cylinder. A frequency of vortex shedding was gained from the acquired images.

  19. Fish survey, fishing duration and other data from otter trawls and scuba observations from NOAA Ship MILLER FREEMAN and other platforms as part of Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 1977-11-04 to 1979-11-26 (NODC Accession 8100532)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fish survey, fishing duration, and other data were collected from otter trawls and scuba diver observations from NOAA Ship MILLER FREEMAN and other platforms from 04...

  20. Structural and electronic properties of non-magnetic intermetallic YAuX (X = Ge and Si) in hexagonal and cubic phases

    Indian Academy of Sciences (India)

    A Lekhal; F Z Benkhelifa; S Méçabih; B Abbar; B Bouhafs

    2016-02-01

    The structural and electronic properties of non-magnetic intermetallic YAuX (X = Ge and Si) crystallized in hexagonal phase have been investigated using the full potential linearized augmented-plane wave (FPLAPW) method based on the density functional theory (DFT), within the generalized gradient approximation (GGA). The calculated lattice parameters were in good agreement with experiment. Also, the structural and electronic properties of the non-magnetic half-Heusler YAuPb compound including the artificial YAuX (X = Ge and Si) calculated in cubic phase were determined. It was found that the half-Heusler YAuPb compound presented metallic character. The results showed that YAuGe in cubic phase is a semiconductor whereas the cubic YAuSi is an isolator.

  1. The impulsive motion of a small cylinder at an interface

    Science.gov (United States)

    Vella, Dominic; Li, Jie

    2010-05-01

    We study the unsteady motion caused by an impulse acting at time t =0 on a small cylinder floating horizontally at a liquid-gas interface. This is a model for the impact of a cylinder onto a liquid surface after the initial splash. Following the impulse, the motion of the cylinder is determined by its weight per unit length (pulling it into the bulk liquid) and resistance from the liquid, which acts to keep the cylinder at the interface. The range of cylinder radii r and impact speeds U considered is such that the resistance from the liquid comes from both the interfacial tension and hydrodynamic pressures. We use two theoretical approaches to investigate this problem. In the first, we apply the arbitrary Lagrangian Eulerian (ALE) method developed by Li et al. ["An arbitrary Lagrangian Eulerian method for moving-boundary problems and its application to jumping over water," J. Comput. Phys. 208, 289 (2005)] to compute the fluid flow caused by the impulse and the (coupled) motion of the cylinder. We show that at early times the interfacial deformation is given by a family of shapes parametrized by r /t2/3. We also find that for a given density and radius there is a critical impulse speed below which the cylinder is captured by the interface and floats but above which it pierces the interface and sinks. Our second theoretical approach is a simplified one in which we assume that the interface is in equilibrium and derive an ordinary differential equation for the motion of the cylinder. Solving this we again find the existence of a critical impulse speed for sinking giving us some quantitative understanding of the results from the ALE simulations. Finally, we compare our theoretical predictions with the results of experiments for cylinder impacts by Vella and Metcalfe ["Surface tension dominated impact," Phys. Fluids 19, 072108 (2007)]. This comparison suggests that the influence of contact line effects, neglected here, may be important in the transition from floating

  2. Composite reinforced metallic cylinder for? high-speed rotation

    Science.gov (United States)

    Pradhan, Sahadev, , Dr.

    2017-01-01

    The objective of the present study is to design and development of the composite reinforced thin metallic cylinder to increase the peripheral speed significantly and thereby? improve the separation performance in a centrifugal gas separation processes through? proper optimization of the internal parameters. According to Dirac equation (Cohen? (1951)), the maximum separative work for a centrifugal gas separation process increase? with 4th power of the peripheral speed. Therefore, it has been intended to reinforce the? metallic cylinder with composites (carbon fibers: T-700 and T- 1000 grade with suitable? epoxy resin) to increase the stiffness and hoop stress so that the peripheral speed can? be increased significantly, and thereby enhance the separative output. Here, we have developed the mathematical model to investigate the elastic stresses of? a laminated cylinder subjected to mechanical, thermal and thermo-mechanical loading? A detailed analysis is carried out to underline the basic hypothesis of each formulation? Further, we evaluate the steady state creep response of the rotating cylinder and analyze? the stresses and strain rates in the cylinder.

  3. Analysis of Aerodynamic Noise Generated from Inclined Circular Cylinder

    Institute of Scientific and Technical Information of China (English)

    YasutakeHaramoto; ShoujiYasuda; 等

    2000-01-01

    Making clear the generation mechanism of fluid dynamic noise is essential to reduce noise deriving from turbomachinery.The analysis of the aerodynamic noise generated from circular cylinder is carried out numerically and experimentally in a low noise wind tunnel.in this study,aerodynamic sound radiated from a circular cylinder in uniform flow is predicted numericaslly by the following two step method,First,the three-dimensional unsteady incompressible Navier-Stokes equation is solved using the high order accurate upwind scheme.Next.the sound pressure level at the observed point is calculated from the fluctuating surface pressure on the cylinder.based on modified Lighthill-Curl's equation.It is worth to note that the noise generated from the model is reduced rapidly when it is inclined against the mean flow.In other works,the Peak level of the radiated noise decreases apidly with inclination of the circular cylinder.The simulated SPL for the inclined circular cylinder is compared with the measured value .and good agreement is obtained for the peak spectrum fequency of the sound pressue level and tendency of noise reduction,So we expect that the change of flow structures makes reduction of the aerodynamic noise from the inclined models.

  4. Analysis of aerodynamic noise generated from inclined circular cylinder

    Science.gov (United States)

    Haramoto, Yasutake; Yasuda, Shouji; Matsuzaki, Kazuyoshi; Munekata, Mizue; Ohba, Hideki

    2000-06-01

    Making clear the generation mechanism of fluid dynamic noise is essential to reduce noise deriving from turbomachinery. The analysis of the aerodynamic noise generated from circular cylinder is carried out numerically and experimentally in a low noise wind tunnel. In this study, aerodynamic sound radiated from a circular cylinder in uniform flow is predicted numerically by the following two step method. First, the three-dimensional unsteady incompressible Navier-Stokes equation is solved using the high order accurate upwind scheme. Next, the sound pressure level at the observed point is calculated from the fluctuating surface pressure on the cylinder, based on modified Lighthill-Curl’s equation. It is worth to note that the noise generated from the model is reduced rapidly when it is inclined against the mean flow. In other words, the peak level of the radiated noise decreases rapidly with inclination of the circular cylinder. The simulated SPL for the inclined circular cylinder is compared with the measured value, and good agreement is obtained for the peak spectrum frequency of the sound pressure level and tendency of noise reduction. So we expect that the change of flow structures makes reduction of the aerodynamic noise from the inclined models.

  5. Modeling flow for modified concentric cylinder rheometer geometry

    Science.gov (United States)

    Ekeruche, Karen; Connelly, Kelly; Kavehpour, H. Pirouz

    2016-11-01

    Rheology experiments on biological fluids can be difficult when samples are limited in volume, sensitive to degradation, and delicate to extract from tissues. A probe-like geometry has been developed to perform shear creep experiments on biological fluids and to use the creep response to characterize fluid material properties. This probe geometry is a modified concentric cylinder setup, where the gap is large and we assume the inner cylinder rotates in an infinite fluid. To validate this assumption we perform shear creep tests with the designed probe on Newtonian and non-Newtonian fluids and vary the outer cylinder container diameter. We have also created a numerical model based on the probe geometry setup to compare with experimental results at different outer cylinder diameters. A creep test is modeled by applying rotation to the inner cylinder and solving for the deformation of the fluid throughout the gap. Steady state viscosity values are calculated from creep compliance curves and compared between experimental and numerical results.

  6. Prediction of External Corrosion for Steel Cylinders 2001 Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmoyer, RLS

    2001-09-17

    The United States Department of Energy (DOE) currently manages the UF{sub 6} Cylinder Project. The project was formed to maintain and safely manage the depleted uranium hexafluoride (UF{sub 6}) stored in approximately 50,000 carbon steel cylinders. The cylinders are located at three DOE sites: the ETTP site (K-25) at Oak Ridge, Tennessee; the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The System Requirements Document (SRD) (LMES 1997a) delineates the requirements of the project. The appropriate actions needed to fulfill these requirements are then specified within the System Engineering Management Plan (SEMP) (LMES 1997b). This report documents activities that in whole or in part satisfy specific requirements and actions stated in the UF{sub 6} Cylinder Project SRD and SEMP with respect to forecasting cylinder conditions. The results presented here supercede those presented previously (Lyon 1995, 1996, 1997, 1998, 2000). Many of the wall thickness projections made in this report are conservative, because they are based on the assumption that corrosion trends will continue, despite activities such as improved monitoring, relocations to better storage, and painting.

  7. Flow around a semicircular cylinder with passive flow control mechanisms

    Science.gov (United States)

    Hamed, A. M.; Vega, J.; Liu, B.; Chamorro, L. P.

    2017-03-01

    Wind tunnel experiments were performed to study the effect of passive flow control strategies on the wake and drag of a semicircular cylinder of infinite aspect ratio. High-resolution planar particle image velocimetry was used to obtain flow statistics around the semicircular cylinder at Reynolds number Re≈ 3.2× 10^4 based on the cylinder diameter. The control mechanisms under consideration include rigid flaps of various lengths placed at the edges of the structure and a small slot along the symmetry plane of the cylinder. Mean velocity fields reveal the distinctive effects of each passive mechanism on the flow, such as velocity recovery, size of the recirculation bubble and location of the reattachment point. The distributions of turbulence kinetic energy and kinematic shear stress show the modulation of each passive control mechanism on the wake, including the onset and location of the maximum turbulence levels. Instantaneous and mean fields of swirling strength further highlight the role of the passive mechanisms in the vortex dynamics. Drag coefficient for the various cases was estimated indirectly from the flow measurements using a momentum balance. This approach shows that long flaps and slot were able to reduce drag with respect to the base case. The rigid flaps with length coincident with the diameter of the cylinder offered the best performance with drag reduction of ˜25%.

  8. Performance of a Horizontal Triple Cylinder Type Pulping Machine

    Directory of Open Access Journals (Sweden)

    Sukrisno Widyotomo

    2011-05-01

    Full Text Available Pulping is one important step in wet coffee processing method. Pulping process usually uses a machine which constructed by wood or metal materials. A horizontal single cylinder type of fresh coffee cherries pulping machine is the most popular machine in coffee processing. One of the weaknesses of a horizontal single cylinder type of fresh coffee cherries pulping machine is higher in broken beans. Broken bean is one of mayor aspects in defect system that contribute to low quality. Indonesian Coffee and Cocoa Research Institute has designed and tested a horizontal double cylinder type of fresh coffee cherries pulping machine which resulted in 12.6—21.4% of broken beans. To reduce percentage of broken beans, Indonesian Coffee and Cocoa Research Institute has developed and tested a horizontal triple cylinder type of fresh coffee cherries pulping machine. Material tested was fresh mature Robusta coffee cherries, 60—65% (wet basis moisture content; has classified on 3 levels i.e. unsorted, small and medium, and clean from metal and foreign materials. The result showed that the machine produced 6,340 kg/h in optimal capacity for operational conditions, 1400 rpm rotor rotation speed for unsorted coffee cherries with composition 55.5% whole parchment coffee, 3.66% broken beans, and 1% beans in wet skin.Key words : coffee, pulp, pulper, cylinder, quality.

  9. Mechanism of Secondary Instability of Flow around a Circular Cylinder

    Science.gov (United States)

    Dou, Hua-Shu; Ben, An-Qing; Fluid Mechanics Research Team Team

    2016-11-01

    Flow around a circular cylinder in infinite domain is simulated with large eddy simulation at Re =200, and the mechanism of the origin of secondary vortex street is analyzed. The simulation results show that the vortex street generated in the cylinder near wake disappears as the flow moving downstream. Secondary instability occurs in far wake of the cylinder after the primary vortex street dying away. The processes of first instability and secondary instability in the cylinder wake are recorded in the simulation. The instability of the entire flow field is studied with the energy gradient theory. It is found that it is the high value of the energy gradient function generated by the zero velocity gradients that leads to the instability. As the vortex developing at rear of the cylinder, the value of the energy gradient function becomes low downstream, which leads to the vortex dying away. At further downstream, the value of the energy gradient function is enlarged again because of the role of perturbation, which leads to the secondary instability. It can be concluded that the interaction of the variation of the value of the energy gradient function and the perturbation leads to the occurrence of secondary instability.

  10. Study of the wake flow around a circular cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Sung; Kim, Sang Il; Seung, Sam Sun [Kangwon National University, Chuncheon (Korea, Republic of)

    2015-11-15

    This experimental study investigated the wake flow around an elastically supported circular cylinder. In this study, the Reynolds numbers are varied in the region of 1.4x10{sup 4}≤Re≤3.2x10{sup 4}. Under these conditions, we have captured the process of the wake mechanism and the moving path of the vortex by measuring the velocity at each position in the wake around the cylinder. Further, these facts from the wind tunnel test are proved by a flow visualization test through a water channel. From the result, we have arrived at the following conclusions : i) The process (formationgrowthcollapse) of vortex is observed in the wake around the cylinder, ii) The vortex efflux angle is approximately 16 degrees⁓17 degrees under the experimental conditions. These angles have no relationship with the velocity change and the existence of flow-induced vibrations of the cylinder, and iii) The moving path of the vortex center is obtained by spectrum analysis of the fluctuating velocity behind the cylinder. These are confirmed by conducting visualization tests.

  11. Spatial damping of propagating sausage waves in coronal cylinders

    Science.gov (United States)

    Guo, Ming-Zhe; Chen, Shao-Xia; Li, Bo; Xia, Li-Dong; Yu, Hui

    2015-09-01

    Context. Sausage modes are important in coronal seismology. Spatially damped propagating sausage waves were recently observed in the solar atmosphere. Aims: We examine how wave leakage influences the spatial damping of sausage waves propagating along coronal structures modeled by a cylindrical density enhancement embedded in a uniform magnetic field. Methods: Working in the framework of cold magnetohydrodynamics, we solve the dispersion relation (DR) governing sausage waves for complex-valued, longitudinal wavenumber k at given real angular frequencies ω. For validation purposes, we also provide analytical approximations to the DR in the low-frequency limit and in the vicinity of ωc, the critical angular frequency separating trapped from leaky waves. Results: In contrast to the standing case, propagating sausage waves are allowed for ω much lower than ωc. However, while able to direct their energy upward, these low-frequency waves are subject to substantial spatial attenuation. The spatial damping length shows little dependence on the density contrast between the cylinder and its surroundings, and depends only weakly on frequency. This spatial damping length is of the order of the cylinder radius for ω ≲ 1.5vAi/a, where a and vAi are the cylinder radius and the Alfvén speed in the cylinder, respectively. Conclusions: If a coronal cylinder is perturbed by symmetric boundary drivers (e.g., granular motions) with a broadband spectrum, wave leakage efficiently filters out the low-frequency components.

  12. Hydrogen Bubbles as a Visualization Tool for Cylinder Shedding

    Science.gov (United States)

    Sigurdson, Lorenz; Gilbert, Stuart

    2004-11-01

    We examine the behavior of hydrogen bubbles formed by electrolysis of water on a 2.54 mm cylindrical electrode in a water tunnel. The Reynolds Number based on cylinder diameter varies from 400 to 1100, and tunnel velocities range from 17 to 50 cm/s. At the lowest velocity buoyancy is a strong effect which inhibits accurate flow tracking by the bubbles. This effect largely disappears by 25 cm/s. As the tunnel velocity increases, bubble size decreases, reflected light for photography is reduced, and bubbles begin to track the von Karman vortex street vortex cores near the cylinder. The vortex cores have a sufficiently low pressure to capture the bubbles. Vortex street wavelength is seen to discretely increase as vortices proceed downstream. The location of this scale-change becomes nearer the cylinder as Re increases. Voids of bubbles occur in continuous linear downstream segments originating near the cylinder. They seem to be due to vortex modification in the wake similar to what other cylinder shedding researchers have found.

  13. Numerical simulation of low-Reynolds number flows past two tandem cylinders of different diameters

    Directory of Open Access Journals (Sweden)

    Yong-tao WANG

    2013-10-01

    Full Text Available The flow past two tandem circular cylinders of different diameters was simulated using the ?nite volume method. The diameter of the downstream main cylinder (D was kept constant, and the diameter of the upstream control cylinder (d varied from 0.1D to D. The studied Reynolds numbers based on the diameter of the downstream main cylinder were 100 and 150. The gap between the control cylinder and the main cylinder (G ranged from 0.1D to 4D. It is concluded that the gap-to-diameter ratio (G/D and the diameter ratio between the two cylinders (d/D have important effects on the drag and lift coef?cients, pressure distributions around the cylinders, vortex shedding frequencies from the two cylinders, and ?ow characteristics.

  14. Electromagnetic Casimir Forces of Parabolic Cylinder and Knife-Edge Geometries

    CERN Document Server

    Graham, Noah; Emig, Thorsten; Rahi, Sahand Jamal; Jaffe, Robert L; Kardar, Mehran

    2011-01-01

    An exact calculation of electromagnetic scattering from a perfectly conducting parabolic cylinder is employed to compute Casimir forces in several configurations. These include interactions between a parabolic cylinder and a plane, two parabolic cylinders, and a parabolic cylinder and an ordinary cylinder. To elucidate the effect of boundaries, special attention is focused on the "knife-edge" limit in which the parabolic cylinder becomes a half-plane. Geometrical effects are illustrated by considering arbitrary rotations of a parabolic cylinder around its focal axis, and arbitrary translations perpendicular to this axis. A quite different geometrical arrangement is explored for the case of an ordinary cylinder placed in the interior of a parabolic cylinder. All of these results extend simply to nonzero temperatures.

  15. Numerical and Experimental Investigation of Circulation in Short Cylinders

    CERN Document Server

    Kageyama, A; Goodman, J; Chen, F; Shoshan, E; Kageyama, Akira; Ji, Hantao; Goodman, Jeremy; Chen, Fei; Shoshan, Ethan

    2004-01-01

    In preparation for an experimental study of magnetorotational instability (MRI) in liquid metal, we explore Couette flows having height comparable to the gap between cylinders, centrifugally stable rotation, and high Reynolds number. Experiments in water are compared with numerical simulations. Simulations show that endcaps corotating with the outer cylinder drive a strong poloidal circulation that redistributes angular momentum. Predicted azimuthal flow profiles agree well with experimental measurements. Spin-down times scale with Reynolds number as expected for laminar Ekman circulation; extrapolation from two-dimensional simulations at $Re\\le 3200$ agrees remarkably well with experiment at $Re\\sim 10^6$. This suggests that turbulence does not dominate the effective viscosity. Further detailed numerical studies reveal a strong radially inward flow near both endcaps. After turning vertically along the inner cylinder, these flows converge at the midplane and depart the boundary in a radial jet. To minimize th...

  16. Actuator placement for active sound and vibration control of cylinders

    Science.gov (United States)

    Kincaid, Rex K.

    1995-01-01

    Active structural acoustic control is a method in which the control inputs (used to reduce interior noise) are applied directly to a vibrating structural acoustic system. The control concept modeled in this work is the application of in-plane force inputs to piezoceramic patches bonded to the wall of a vibrating cylinder. The cylinder is excited by an exterior noise source -- an acoustic monopole -- located near the outside of the cylinder wall. The goal is to determine the force inputs and sites for the piezoelectric actuators so that (1) the interior noise is effectively damped; (2) the level of vibration of the cylinder shell is not increased; and (3) the power requirements needed to drive the actuators are not excessive. We studied external monopole excitations at two frequencies. A cylinder resonance of 100 Hz, where the interior acoustic field is driven in multiple, off-resonance cylinder cavity modes, and a cylinder resonance of 200 Hz are characterized by both near and off-resonance cylinder vibration modes which couple effectively with a single, dominant, low-order acoustic cavity mode at resonance. Previous work has focused almost exclusively on meeting objective (1) and solving a complex least-squares problem to arrive at an optimal force vector for a given set of actuator sites. In addition, it has been noted that when the cavity mode couples with cylinder vibration modes (our 200 Hz case) control spillover may occur in higher order cylinder shell vibrational modes. How to determine the best set of actuator sites to meet objectives (1)-(3) is the main contribution of our research effort. The selection of the best set of actuator sites from a set of potential sites is done via two metaheuristics -- simulated annealing and tabu search. Each of these metaheuristics partitions the set of potential actuator sites into two disjoint sets: those that are selected to control the noise (on) and those that are not (off). Next, each metaheuristic attempts to

  17. Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

    Science.gov (United States)

    Johnson, Arthur R.; Chen, Tzi-Kang

    2002-01-01

    Thick rubber components are employed by the Army to carry large loads. In tanks, rubber covers road wheels and track systems to protect roadways. It is difficult for design engineers to simulate the details of the hysteretic heating for large strain viscoelastic deformations. In this study, an approximation to the viscoelastic energy dissipated per unit time is investigated for use in estimating mechanically induced viscoelastic heating. Coupled thermo-mechanical simulations of large cyclic deformations of rubber cylinders are presented. The cylinders are first compressed axially and then cyclically loaded about the compressed state. Details of the algorithm and some computational issues are discussed. The coupled analyses are conducted for tall and short rubber cylinders both with and without imbedded metal disks.

  18. Stirring by multi-cylinder in potential flow

    CERN Document Server

    Zhang, Yuanzhao

    2014-01-01

    We analyze the mixing efficiency of multiple-cylinder in potential flow to assess the effect of schooling in ocean-biomixing. The model is a generalization of Thiffeault & Childress's work [Physics Letters A 374, 3487 (2010)], where fluid particle displacements due to a single inviscid swimmer were analyzed to produce an effective diffusivity. Here we climb the population ladder to see how the interaction among swimmers would influence the motion of particles in the flow. Two cylinders moving synchronously through the flow in various angles and separations were studied, with several important patterns revealed---when the separation is small (less than $\\frac{1}{3}$ body length), two cylinders moving side-by-side ($\\theta=\\pi/2$) has the highest mixing efficiency, while the chasing configuration ($\\theta=0$) takes over for larger separations. But regardless of the angle and separation, the normalized effective diffusivity is constantly higher than single-swimmer value, which indicates schooling effect as a...

  19. Casimir effect at nonzero temperature for wedges and cylinders

    CERN Document Server

    Ellingsen, Simen Å; Milton, Kimball A

    2010-01-01

    We consider the Casimir-Helmholtz free energy at nonzero temperature $T$ for a circular cylinder and perfectly conducting wedge closed by a cylindrical arc, either perfectly conducting or isorefractive. The energy expression at nonzero temperature may be regularized to obtain a finite value, except for a singular corner term in the case of the wedge which is present also at zero temperature. Assuming the medium in the interior of the cylinder or wedge be nondispersive with refractive index $n$, the temperature dependence enters only through the non-dimensional parameter $2\\pi naT$, $a$ being the radius of the cylinder or cylindrical arc. We show explicitly that the known zero temperature result is regained in the limit $aT\\to 0$ and that previously derived high temperature asymptotics for the cylindrical shell are reproduced exactly.

  20. Chaos Control in the Wake of an Oscillating Cylinder

    Science.gov (United States)

    Balasubramanian, Ganapathi R.; Olinger, David J.

    1997-11-01

    The nonlinear dynamics of vortex shedding behind circular cylinders are investigated using a previously developed spatial-temporal map lattice. The map studied consists of a series of circle map oscillators placed along the cylinder span coupled with a simple diffusion model. Chaotic states associated with disordered vortex shedding patterns are observed when forcing the cylinder outside the classical lock-on region. These are controlled through application of a small-amplitude periodic perturbation of a system parameter, as proposed by Ott, Grebogi, and Yorke. Periodic lace-like structures and parallel shedding patterns are realized by driving the chaotic system to the desired target state. A wide range of forcing frequency-amplitude combinations are studied along with manipulation of vortex lock-on region extents. Preliminary extensions of these chaos control techniques to a two-dimensional wake flow using finite element techniques are also discussed.

  1. Instability of Taylor-Couette Flow between Concentric Rotating Cylinders

    CERN Document Server

    Dou, H S; Phan-Thien, N; Yeo, K S; Dou, Hua-Shu; Khoo, Boo Cheong; Phan-Thien, Nhan; Yeo, Koon Seng

    2005-01-01

    The energy gradient theory is used to study the instability of Taylor-Couette flow between concentric rotating cylinders. In our previous studies, the energy gradient theory was demonstrated to be applicable for wall bounded parallel flows. It was found that the critical value of the energy gradient parameter K at subcritical transition is about 370-389 for wall bounded parallel flows (which include plane Poiseuille flow, pipe Poiseuille flow and plane Couette flow) below which no turbulence occurs. In this paper, the detailed derivation for the calculation of the energy gradient parameter in the flow between concentric rotating cylinders is provided. The theoretical results for the critical condition of primary instability obtained are in very good agreement with the experiments found in literature. The mechanism of spiral vortices generation for counter-rotating of two cylinders is also explained using the energy gradient theory. The energy gradient theory can also serve to relate the condition of flow tran...

  2. Stitching interferometry of a full cylinder without using overlap areas

    Science.gov (United States)

    Peng, Junzheng; Chen, Dingfu; Yu, Yingjie

    2017-08-01

    Traditional stitching interferometry requires finding out the overlap correspondence and computing the discrepancies in the overlap regions, which makes it complex and time-consuming to obtain the 360° form map of a cylinder. In this paper, we develop a cylinder stitching model based on a new set of orthogonal polynomials, termed Legendre Fourier (LF) polynomials. With these polynomials, individual subaperture data can be expanded as a composition of the inherent form of a partial cylinder surface and additional misalignment parameters. Then the 360° form map can be acquired by simultaneously fitting all subaperture data with the LF polynomials. A metal shaft was measured to experimentally verify the proposed method. In contrast to traditional stitching interferometry, our technique does not require overlapping of adjacent subapertures, thus significantly reducing the measurement time and making the stitching algorithm simple.

  3. Image analysis of moving seeds in an indented cylinder

    DEFF Research Database (Denmark)

    Buus, Ole; Jørgensen, Johannes Ravn

    2010-01-01

    -Spline surfaces. Using image analysis, the seeds will be tracked using a kalman filter and the 2D trajectory, length, velocity, weight, and rotation will be sampled. We expect a high correspondence between seed length and certain spatially optimal seed trajectories. This work is done in collaboration with Westrup...... threshold. The threshold is dependent on a number of different parameters. Besides the seed length, the rotation, general size, shape, and surface texture of each seed, are also known to influence the final sorting result. Such knowledge comes from previous experimentation with the indented cylinder. In our...... work we will seek to understand more about the internal dynamics of the indented cylinder. We will apply image analysis to observe the movement of seeds in the indented cylinder. This work is laying the groundwork for future studies into the application of image analysis as a tool for autonomous...

  4. Heat of detonation, the cylinder test, and performance munitions

    Energy Technology Data Exchange (ETDEWEB)

    Akst, I.B.

    1989-01-01

    Heats of detonation of CHNO explosives correlate well with copper cylinder test expansion data. The detonation products/calorimetry data can be used to estimate performance in the cylinder test, in munitions, and for new molecules or mixtures of explosives before these are made. Confidence in the accuracy of the performance estimates is presently limited by large deviations of a few materials from the regression predictions; but these same deviations, as in the insensitive explosive DINGU and the low carbon systems, appear to be sources of information useful for detonation and explosives research. The performance correlations are functions more of the detonation products and thermochemical energy than they are of the familiar parameters of detonation pressure and velocity, and the predictions are closer to a regression line on average than are those provided by CJ calculations. The prediction computations are simple but the measurements (detonation calorimetry/products and cylinder experiments) are not. 17 refs., 5 tabs.

  5. Filament winding cylinders. II - Validation of the process model

    Science.gov (United States)

    Calius, Emilio P.; Lee, Soo-Yong; Springer, George S.

    1990-01-01

    Analytical and experimental studies were performed to validate the model developed by Lee and Springer for simulating the manufacturing process of filament wound composite cylinders. First, results calculated by the Lee-Springer model were compared to results of the Calius-Springer thin cylinder model. Second, temperatures and strains calculated by the Lee-Springer model were compared to data. The data used in these comparisons were generated during the course of this investigation with cylinders made of Hercules IM-6G/HBRF-55 and Fiberite T-300/976 graphite-epoxy tows. Good agreement was found between the calculated and measured stresses and strains, indicating that the model is a useful representation of the winding and curing processes.

  6. Heat transfer in a conical porous cylinder with partial heating

    Science.gov (United States)

    Yunus Khan, T. M.; Anjum Badruddin, Irfan; Quadir, G. A.

    2016-09-01

    The current work simulates the heat transfer across a porous medium fixed in an annular conical cylinder. The geometry is such that the lower part is conical annulus supporting a regular annular cylinder. The porous medium is fixed between inner and outer radius of conical annular cylinder. The inner radius until conical section is heated with constant temperature Th whereas the outer radius is cooled to isothermal temperature Tc such that Th>Tc . The heat transfer phenomenon in this case can be described by two coupled partial differential equations which are solved using finite element method by using 3-node triangular elements. The heat transfer characteristics in this case are quite different from other geometries being discussed in the literature. It is observed that the fluid flow is stronger in the conical section as compared to the cylindrical part of porous geometry. A very few isothermal lines penetrate into the cylindrical porous region as compared to that of conical section.

  7. Sensitivity analysis of small circular cylinders as wake control

    Science.gov (United States)

    Meneghini, Julio; Patino, Gustavo; Gioria, Rafael

    2016-11-01

    We apply a sensitivity analysis to a steady external force regarding control vortex shedding from a circular cylinder using active and passive small control cylinders. We evaluate the changes on the flow produced by the device on the flow near the primary instability, transition to wake. We numerically predict by means of sensitivity analysis the effective regions to place the control devices. The quantitative effect of the hydrodynamic forces produced by the control devices is also obtained by a sensitivity analysis supporting the prediction of minimum rotation rate. These results are extrapolated for higher Reynolds. Also, the analysis provided the positions of combined passive control cylinders that suppress the wake. The latter shows that these particular positions for the devices are adequate to suppress the wake unsteadiness. In both cases the results agree very well with experimental cases of control devices previously published.

  8. Optimal control of circular cylinder wakes using long control horizons

    CERN Document Server

    Flinois, Thibault L B

    2015-01-01

    The classical problem of minimizing the drag of a circular cylinder by using body rotation is revisited in an adjoint-based optimal control framework. The cylinder's unsteady and fully unconstrained rotation rate is optimized at Reynolds numbers of 100 and 200 and over horizons that are longer than in previous studies, where they are typically of the order of a vortex shedding period or shorter. In the best configuration, the drag is reduced by $19\\%$, the vortex shedding is effectively suppressed, and this low drag state is maintained with minimal cylinder rotation after transients. Without closed-loop control, which maintains a specific phase relationship between the actuation and the shedding, the wake is not stabilized. A comparison is also given between the performance of optimizations for different horizon lengths and cost functions. It is shown that the long horizons used are necessary in order to stabilize the vortex shedding efficiently.

  9. Efficient manipulation of graphene absorption by a simple dielectric cylinder.

    Science.gov (United States)

    Xiao, Ting-Hui; Gan, Lin; Li, Zhi-Yuan

    2015-07-27

    We theoretically study the absorption property of graphene manipulated by a dielectric cylinder through an analytical method. The distinctive absorption properties of incident waves with different polarizations (TM and TE) are analyzed and they are strongly correlated with the structure resonance and material dispersion. Besides, the characteristics of graphene absorption tuned by the cylinder radius and refractive index as well as the chemical potential of graphene are systematically investigated. It is found that enhancement and continuous tunability of graphene absorption can be achieved by utilizing the whispering gallery mode produced in the dielectric cylinder and harnessing the graphene optical conductivity via tuning its chemical potential by exterior electrical grating. The theoretical studies open up a simple while efficient means to manipulate the absorption of graphene in a broad frequency range via the geometric and physical configuration of hybrid graphene-microstructures.

  10. Fast transforms for rapid isolation of misfiring cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Rizzoni, G.

    1987-01-01

    This paper presents a method for the isolation of misfiring cylinders in an internal combustion engine. The method is based on the measurement of the extrema of engine angular velocity. It has been shown that a number of indices can be derived from such a measurement, to provide an indication of engine performance degradation. In this study, an onboard microprocessor-based instrument samples the extrema of the engine velocity waveform in real time, generating an N or 2N vector representing each engine cycle, where N is the number of cylinders. The system is capable of detecting individual or multiple cylinder misfires, both complete and partial. Experimental verification has been carried out in a passenger vehicle. The intent of this paper is to outline the theory underlying the method, and to demonstrate its feasibility by performing some simple experiments on a production engine.

  11. Measurement of the flow past a cactus-inspired cylinder

    Science.gov (United States)

    Oweis, Ghanem F.; El-Makdah, Adnan M.

    2012-11-01

    Desert cacti are tall cylindrical plants characterized by longitudinal u- or v-shaped grooves that run parallel to the plant axis, covering its surface area. We study the wake flow modifications resulting from the introduction of cactus-inspired surface grooves to a circular cylinder. Particle image velocimetry PIV is implemented in a wind tunnel to visualize and quantify the wake flow from a cactus cylinder in cross wind and an equivalent circular cylinder at Re O(1E5). The cactus wake exhibits superior behavior over its circular counterpart as seen from the mean and turbulent velocity profiles. The surface flow within the grooves is also probed to elucidate the origins of the wake alterations. Lastly, we use simple statistical analysis based only on the wake velocity fields, under the assumption of periodicity of the shedding, to recover the time varying flow from the randomly acquired PIV snapshots.

  12. The Working Mechanism and An Analytic Method of the Deep Embedded Large Cylinder Structure

    Institute of Scientific and Technical Information of China (English)

    孙克俐; 周锡礽; 钱荣

    2004-01-01

    The large cylinder is a new-type structure that has been applied to harbor and offshore engineering. An analytic method of the relationship between loads and the structure displacement is developed based on the failure mode of deep embedded large cylinder structures. It can be used to calculate directly the soil resistance and the ultimate bearing capacity of the structure under usage. A new criterion of the large cylinder structure, which discriminates the deep embedded cylinder from the shallow embedded cylinder, is defined. Model tests prove that the proposed method is feasible for the analysis of deep embedded large cylinder structures.

  13. Pulsatility role in cylinder flow dynamics at low Reynolds number

    KAUST Repository

    Qamar, Adnan

    2012-01-01

    We present dynamics of pulsatile flow past a stationary cylinder characterized by three non-dimensional parameters: the Reynolds number (Re), non-dimensional amplitude (A) of the pulsatile flow velocity, and Keulegan-Carpenter number (KC = Uo/Dωc). This work is motivated by the development of total artificial lungs (TAL) device, which is envisioned to provide ambulatory support to patients. Results are presented for 0.2 ≤ A ≤ 0.6 and 0.57 ≤ KC ≤ 2 at Re = 5 and 10, which correspond to the operating range of TAL. Two distinct fluid regimes are identified. In both regimes, the size of the separated zone is much greater than the uniform flow case, the onset of separation is function of KC, and the separation vortex collapses rapidly during the last fraction of the pulsatile cycle. The vortex size is independent of KC, but with an exponential dependency on A. In regime I, the separation point remains attached to the cylinder surface. In regime II, the separation point migrates upstream of the cylinder. Two distinct vortex collapse mechanisms are observed. For A < 0.4 and all KC and Re values, collapse occurs on the cylinder surface, whereas for A > 0.4 the separation vortex detaches from the cylinder surface and collapses at a certain distance downstream of the cylinder. The average drag coefficient is found to be independent of A and KC, and depends only on Re. However, for A > 0.4, for a fraction of the pulsatile cycle, the instantaneous drag coefficient is negative indicating a thrust production. © 2012 American Institute of Physics.

  14. Vortex shedding noise of a cylinder with hairy flaps

    Science.gov (United States)

    Kamps, Laura; Geyer, Thomas F.; Sarradj, Ennes; Brücker, Christoph

    2017-02-01

    This study describes the modification of acoustic noise emitted from cylinders in a stationary subsonic flow for a cylinder equipped with flexible hairy flaps at the aft part as a passive way to manipulate the flow and acoustics. The study was motivated by the results from previous water tunnel measurements, which demonstrated that hairy flaps can modify the shedding cycle behind the cylinder and can reduce the wake deficit. In the present study, wind tunnel experiments were conducted on such a modified cylinder and the results were compared to the reference case of a plain cylinder. The acoustic spectrum was measured using two microphones while simultaneously recording the flap motion. To further examine the flow structures in the downstream vicinity of the cylinder, constant temperature anemometry measurements as well as flow visualizations were also performed. The results show that, above a certain Reynolds number, the hairy flaps lead to a jump in the vortex shedding frequency. This phenomenon is similarly observed in the water flow experiments as a jump in the non-dimensional Strouhal number that is related to the change of the shedding cycle. This jump appears to be coupled to a resonant excitation of the flaps. The specific Reynolds number at which the jump occurs is higher in the present case, which is attributed to the lower added mass in air as compared with the one in water. The flow visualizations confirmed that such action of the flaps lead to a more slender elongated shape of the time-averaged separation bubble. In addition, the hairy flaps induce a noticeable reduction of the tonal noise as well as broadband noise as long as the flaps do not touch each other.

  15. Stratified spin-up in a sliced, square cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Munro, R. J. [Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Foster, M. R. [Department of Mathematical Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2014-02-15

    We previously reported experimental and theoretical results on the linear spin-up of a linearly stratified, rotating fluid in a uniform-depth square cylinder [M. R. Foster and R. J. Munro, “The linear spin-up of a stratified, rotating fluid in a square cylinder,” J. Fluid Mech. 712, 7–40 (2012)]. Here we extend that analysis to a “sliced” square cylinder, which has a base-plane inclined at a shallow angle α. Asymptotic results are derived that show the spin-up phase is achieved by a combination of the Ekman-layer eruptions (from the perimeter region of the cylinder's lid and base) and cross-slope-propagating stratified Rossby waves. The final, steady state limit for this spin-up phase is identical to that found previously for the uniform depth cylinder, but is reached somewhat more rapidly on a time scale of order E{sup −1/2}Ω{sup −1}/log (α/E{sup 1/2}) (compared to E{sup −1/2}Ω{sup −1} for the uniform-depth cylinder), where Ω is the rotation rate and E the Ekman number. Experiments were performed for Burger numbers, S, between 0.4 and 16, and showed that for S≳O(1), the Rossby modes are severely damped, and it is only at small S, and during the early stages, that the presence of these wave modes was evident. These observations are supported by the theory, which shows the damping factors increase with S and are numerically large for S≳O(1)

  16. Assembly for electrical conductivity measurements in the piston cylinder device

    Science.gov (United States)

    Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  17. Image analysis of moving seeds in an indented cylinder

    DEFF Research Database (Denmark)

    Buus, Ole; Jørgensen, Johannes Ravn

    2010-01-01

    -Spline surfaces. Using image analysis, the seeds will be tracked using a kalman filter and the 2D trajectory, length, velocity, weight, and rotation will be sampled. We expect a high correspondence between seed length and certain spatially optimal seed trajectories. This work is done in collaboration with Westrup...... work we will seek to understand more about the internal dynamics of the indented cylinder. We will apply image analysis to observe the movement of seeds in the indented cylinder. This work is laying the groundwork for future studies into the application of image analysis as a tool for autonomous...

  18. Nonlinear Fracture Mechanics and Plasticity of the Split Cylinder Test

    DEFF Research Database (Denmark)

    Olesen, John Forbes; Østergaard, Lennart; Stang, Henrik

    2006-01-01

    demonstrates the influence of varying geometry or constitutive properties. For a split cylinder test in load control it is shown how the ultimate load is either plasticity dominated or fracture mechanics dominated. The transition between the two modes is related to changes in geometry or constitutive......The split cylinder testis subjected to an analysis combining nonlinear fracture mechanics and plasticity. The fictitious crack model is applied for the analysis of splitting tensile fracture, and the Mohr-Coulomb yield criterion is adopted for modelling the compressive crushing/sliding failure. Two...

  19. Topology of vortex creation in the cylinder wake

    DEFF Research Database (Denmark)

    Brøns, Morten; Bisgaard, Anders Villefrance

    2010-01-01

    We analyze the topology of the two-dimensional flow around a circular cylinder at moderate Reynolds numbers in the regime where the vortex wake is created. A normal form for the stream function close to the cylinder is presented and used to predict the streamline pattern both in the steady...... and the periodic regime, where two different vortex shedding scenarios are identified. The theoretical predictions are verified numerically. For the vorticity, a very different topology occurs with infinite nested sequences of iso-curves moving downstream. General equations of motion for critical points...

  20. Design guide for single circular cylinder in turbulent crossflow. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Mulcahy, T.M.

    1982-03-01

    A design procedure is proposed for predicting the dynamic structural response of a circular cylinder in turbulent crossflow. The procedure is based on recently obtained data for a stationary, rigid cylinder and on existing information. The procedure is not applicable to conditions where the wake vortex shedding frequency locks into a structural natural frequency. This report is self-contained in that all the information and structural analysis methods employed in the procedure are reviewed and developed. Also, an example is given to illustrate the use of the method for a typical reactor component. The calculated responses are found to be very small.

  1. Four-Cylinder Stirling-Engine Computer Program

    Science.gov (United States)

    Daniele, C. J.; Lorenzo, C. F.

    1986-01-01

    Computer program developed for simulating steady-state and transient performance of four-cylinder Stirling engine. In model, four cylinders interconnected by four working spaces. Each working space contains seven volumes: one for expansion space, heater, cooler, and compression space and three for regenerator. Thermal time constant for regenerator mass associated with each regenator gas volume. Former code generates results very quickly, since it has only 14 state variables with no energy equation. Current code then used to study various aspects of Stirling engine in much more detail. Program written in FORTRAN IV for use on IBM 370 computer.

  2. Plasmonic modes and extinction properties of a random nanocomposite cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Basic Sciences, Kermanshah University of Technology, Kermanshah, Iran and Department of Nano Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of)

    2014-04-15

    We study the properties of surface plasmon-polariton waves of a random metal-dielectric nanocomposite cylinder, consisting of bulk metal embedded with dielectric nanoparticles. We use the Maxwell-Garnett formulation to model the effective dielectric function of the composite medium and show that there exist two surface mode bands. We investigate the extinction properties of the system, and obtain the dependence of the extinction spectrum on the nanoparticles’ shape and concentration as well as the cylinder radius and the incidence angle for both TE and TM polarization.

  3. An experiment in heat conduction using hollow cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Ortuno, M; Marquez, A; Gallego, S; Neipp, C; Belendez, A, E-mail: a.belendez@ua.es [Departamento de Fisica, IngenierIa de Sistemas y TeorIa de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)

    2011-07-15

    An experimental apparatus was designed and built to allow students to carry out heat conduction experiments in hollow cylinders made of different materials, as well as to determine the thermal conductivity of these materials. The evolution of the temperature difference between the inner and outer walls of the cylinder as a function of time is analysed, and when the process reaches the steady state regime the thermal conductivity can be easily calculated. Several materials such as wood, plastic and metals are considered and the values of their thermal conductivities, obtained experimentally, are compared with those given in the reference list.

  4. Effect of High Porosity Screen on the Near Wake of a Circular Cylinder

    Directory of Open Access Journals (Sweden)

    Sahin B.

    2013-04-01

    Full Text Available The change in flow characteristics downstream of a circular cylinder (inner cylinder surrounded by a permeable cylinder (outer cylinder made of a high porosity screen was investigated in shallow water using Particle Image Velocimetry (PIV technique. The diameter of the inner cylinder, outer cylinder and the water height were kept constant during the experiments as d = 50 mm, D = 100 mm and hw = 50 mm, respectively. The depth-averaged free stream velocity was also kept constant as U = 180 mm/s which corresponded to a Reynolds number of Red = 9000 based on the inner cylinder diameter. It was shown that the outer permeable cylinder had a substantialeffect on the vortex formation and consequent vortex shedding downstream of the circular cylinder, especially in the near wake. The time averaged vorticity layers, streamlines and velocity vector field depict that the location of the interaction of vortices considerably changed by the presence of the outer cylinder. Turbulent statistics clearly demonstrated that in comparison to the natural cylinder, turbulent kinetic energy and Reynolds stresses decreased remarkably downstream of the inner cylinder. Moreover, spectra of streamwise velocity fluctuations showed that the vortex shedding frequency significantly reduced compared to the natural cylinder case.

  5. Refractive cylinder outcomes after calculating toric intraocular lens cylinder power using total corneal refractive power

    Directory of Open Access Journals (Sweden)

    Davison JA

    2015-08-01

    Full Text Available James A Davison,1 Richard Potvin21Wolfe Eye Clinic, Marshalltown, IA, USA; 2Science in Vision, Akron, NY, USAPurpose: To determine whether the total corneal refractive power (TCRP value, which is based on measurement of both anterior and posterior corneal astigmatism, is effective for toric intraocular lens (IOL calculation with AcrySof® Toric IOLsPatients and methods: A consecutive series of cataract surgery cases with AcrySof toric IOL implantation was studied retrospectively. The IOLMaster® was used for calculation of IOL sphere, the Pentacam® TCRP 3.0 mm apex/ring value was used as the keratometry input to the AcrySof Toric IOL Calculator and the VERION™ Digital Marker for surgical orientation. The keratometry readings from the VERION reference unit were recorded but not used in the actual calculation. Vector differences between expected and actual residual refractive cylinder were calculated and compared to simulated vector errors using the collected VERION keratometry data.Results: In total, 83 eyes of 56 patients were analyzed. Residual refractive cylinder was 0.25 D or lower in 58% of eyes and 0.5 D or lower in 80% of eyes. The TCRP-based calculation resulted in a statistically significantly lower vector error (P<0.01 and significantly more eyes with a vector error ≤0.5 D relative to the VERION-based calculation (P=0.02. The TCRP and VERION keratometry readings suggested a different IOL toric power in 53/83 eyes. In these 53 eyes the TCRP vector error was lower in 28 cases, the VERION error was lower in five cases, and the error was equal in 20 cases. When the anterior cornea had with-the-rule astigmatism, the VERION was more likely to suggest a higher toric power and when the anterior cornea had against-the-rule astigmatism, the VERION was less likely to suggest a higher toric power.Conclusion: Using the TCRP keratometry measurement in the AcrySof toric calculator may improve overall postoperative refractive results

  6. Elastic and viscoelastic solutions to rotating functionally graded hollow and solid cylinders

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Analytical solutions to rotating functionally graded hollow and solid long cylinders are developed. Young's modulus and material density of the cylinder are as* sumed to vary exponentially in the radial direction, and Poisson's ratio is assumed to be constant. A unified governing equation is derived from the equilibrium equations, compat-ibility equation, deformation theory of elasticity and the stress-strain relationship. The governing second-order differential equation is solved in terms of a hypergeometric func-tion for the elastic deformation of rotating functionally graded cylinders. Dependence of stresses in the cylinder on the inhomogeneous parameters, geometry and boundary conditions is examined and discussed. The proposed solution is validated by comparing the results for rotating functionally graded hollow and solid cylinders with the results for rotating homogeneous isotropic cylinders. In addition, a viscoelastic solution to the rotating viscoelastic cylinder is presented, and dependence of stresses in hollow and solid cylinders on the time parameter is examined.

  7. 49 CFR 178.39 - Specification 3BN seamless nickel cylinders.

    Science.gov (United States)

    2010-10-01

    .... A reasonably smooth and uniform surface finish is required. Cylinders closed in by spinning process... nonpressure parts, and only to the tops and bottoms of cylinders. Neckrings and footrings must be of weldable...

  8. A Clustering Genetic Algorithm for Cylinder Drag Optimization

    Science.gov (United States)

    Milano, Michele; Koumoutsakos, Petros

    2002-01-01

    A real coded genetic algorithm is implemented for the optimization of actuator parameters for cylinder drag minimization. We consider two types of idealized actuators that are allowed either to move steadily and tangentially to the cylinder surface (“belts”) or to steadily blow/suck with a zero net mass constraint. The genetic algorithm we implement has the property of identifying minima basins, rather than single optimum points. The knowledge of the shape of the minimum basin enables further insights into the system properties and provides a sensitivity analysis in a fully automated way. The drag minimization problem is formulated as an optimal regulation problem. By means of the clustering property of the present genetic algorithm, a set of solutions producing drag reduction of up to 50% is identified. A comparison between the two types of actuators, based on the clustering property of the algorithm, indicates that blowing/suction actuation parameters are associated with larger tolerances when compared to optimal parameters for the belt actuators. The possibility of using a few strategically placed actuators to obtain a significant drag reduction is explored using the clustering diagnostics of this method. The optimal belt-actuator parameters obtained by optimizing the two-dimensional case is employed in three-dimensional simulations, by extending the actuators across the span of the cylinder surface. The three-dimensional controlled flow exhibits a strong two-dimensional character near the cylinder surface, resulting in significant drag reduction.

  9. Convection from a Slender Cylinder in a Ventilated Room

    DEFF Research Database (Denmark)

    Heiselberg, Per; Sandberg, Mats

    In this paper the equations, based on integral formulation, for the boundary layer flow in the constant heat flux case and in the constant temperature case have been solved, and both a flat plate and a cylinder solution are presented. Results are compared with measurements carried out in the turb...

  10. Properties of Sub-wavelength Resonances in Metamaterial Cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Clausen, N.C.J.; Pedersen, R.R.;

    2008-01-01

    The analytical solution for the canonical configuration with electric line source illumination of concentric metamaterial cylinders is employed to study the properties of the observed sub-wavelength resonances. The near- and far-field distributions, the frequency and geometry bandwidths...

  11. Design of nested Halbach cylinder arrays for magnetic refrigeration applications

    Energy Technology Data Exchange (ETDEWEB)

    Trevizoli, Paulo V., E-mail: trevizoli@polo.ufsc.br; Lozano, Jaime A.; Peixer, Guilherme F.; Barbosa Jr, Jader R.

    2015-12-01

    We present an experimentally validated analytical procedure to design nested Halbach cylinder arrays for magnetic cooling applications. The procedure aims at maximizing the magnetic flux density variation in the core of the array for a given set of design parameters, namely the inner diameter of the internal magnet, the air gap between the magnet cylinders, the number of segments of each magnet and the remanent flux density of the Nd{sub 2}Fe{sub 14}B magnet grade. The design procedure was assisted and verified by 3-D numerical modeling using a commercial software package. An important aspect of the optimal design is to maintain an uniform axial distribution of the magnetic flux density in the region of the inner gap occupied by the active magnetocaloric regenerator. An optimal nested Halbach cylinder array was manufactured and experimentally evaluated for the magnetic flux density in the inner gap. The analytically calculated magnetic flux density variation agreed to within 5.6% with the experimental value for the center point of the magnet gap. - Highlights: • An analytical procedure to design nested Halbach cylinder arrays is proposed. • An optimal magnet configuration was built based on the analytical procedure. • The procedure was validated with 3D COMSOL simulations and experimental data.

  12. Rainbow technique for multi-parameter measurement of absorbing cylinder

    Institute of Scientific and Technical Information of China (English)

    Feihu Song; Chuanlong Xu; Shimin Wang

    2013-01-01

    Rainbow refractometry is widely used to measure the radius and real part of refractive index of a cylinder.However,studies on the detection of imaginary part of the refractive index with rainbow technique were scarce.This paper presents a new method for simultaneously measuring the radius,real and imaginary part of the refractive index of a cylinder,on the basis of the Airy theory and the Bouguer theory.The rainbows produced by the illuminated cylinder at a capillary exit are captured by a CCD camera in a labscale system,and then processed by the proposed method.Experimental results showed that the radius,real and imaginary part of the refractive index can be accurately determined when the SNR (signal to noise ratio) of the ripple structure is sufficiently high.However,the SNR of the ripple structure gradually decreases with decreasing scattering intensity of the cylinder,leading to larger measurement errors of the radius and real part of the refractive index.The relative error of the imaginary part of the refractive index derived from the measurement errors of the radius and real part of the refractive index,is less than 3.4%.

  13. DNS of 2D turbulent flow around a square cylinder

    NARCIS (Netherlands)

    Wissink, JG

    1997-01-01

    Two-dimensional 'turbulent' flow around a rectangular cylinder has been simulated at Re = 10,000 using a sixth-order-accurate finite volume method for the discretization of convection and diffusion. The spatial discretization consists of a combination of a seventh-order upwind-biased method for the

  14. Oscillation of cylinders of rectangular cross section immersed in fluid

    Science.gov (United States)

    Brumley, Douglas R.; Willcox, Michelle; Sader, John E.

    2010-05-01

    The ability to calculate flows generated by oscillating cylinders immersed in fluid is a cornerstone in micro- and nanodevice development. In this article, we present a detailed theoretical analysis of the hydrodynamic load experienced by an oscillating rigid cylinder, of arbitrary rectangular cross section, that is immersed in an unbounded viscous fluid. We also consider the formal limit of inviscid flow for which exact analytical and asymptotic solutions are derived. Due to its practical importance in application to the atomic force microscope and nanoelectromechanical systems, we conduct a detailed assessment of the dependence of this load on the cylinder thickness-to-width ratio. We also assess the validity and accuracy of the widely used infinitely-thin blade approximation. For thin rectangular cylinders of finite thickness, this approximation is found to be excellent for out-of-plane motion, whereas for in-plane oscillations it can exhibit significant error. A database of accurate numerical results for the hydrodynamic load as a function of the thickness-to-width ratio and normalized frequency is also presented, which is expected to be of value in practical application and numerical benchmarking.

  15. Resonances and dipole moments in dielectric, magnetic, and magnetodielectric cylinders

    DEFF Research Database (Denmark)

    Dirksen, A.; Arslanagic, Samel; Breinbjerg, Olav

    2011-01-01

    An eigenfunction solution to the problem of plane wave scattering by dielectric, magnetic, and magnetodielectric cylinders is used for a systematic investigation of their resonances. An overview of the resonances with electric and magnetic dipole moments, needed in, e.g., the synthesis...... of metamaterials, is given with an emphasis on their strength, bandwidth, and isolation....

  16. Mechanisms of noise control inside a finite cylinder

    Science.gov (United States)

    Lester, H. C.

    1988-01-01

    Preliminary results are presented for a simple elastic cylinder/acoustic cavity model. The validity of the mode matching method, which was used to couple the shell vibrations to the interior acoustic response, has been validated by comparison with Junger's (1985) method. In addition, the importance of both structural and acoustic damping in the medium response was shown to be dramatic.

  17. Experimental Thermal Analysis of Diesel Engine Piston and Cylinder Wall

    Directory of Open Access Journals (Sweden)

    Subodh Kumar Sharma

    2015-01-01

    Full Text Available Knowledge of piston and cylinder wall temperature is necessary to estimate the thermal stresses at different points; this gives an idea to the designer to take care of weaker cross section area. Along with that, this temperature also allows the calculation of heat losses through piston and cylinder wall. The proposed methodology has been successfully applied to a water-cooled four-stroke direct-injection diesel engine and it allows the estimation of the piston and cylinder wall temperature. The methodology described here combines numerical simulations based on FEM models and experimental procedures based on the use of thermocouples. Purposes of this investigation are to measure the distortion in the piston, temperature, and radial thermal stresses after thermal loading. To check the validity of the heat transfer model, measure the temperature through direct measurement using thermocouple wire at several points on the piston and cylinder wall. In order to prevent thermocouple wire entanglement, a suitable pathway was designed. Appropriate averaged thermal boundary conditions such as heat transfer coefficients were set on different surfaces for FE model. The study includes the effects of the thermal conductivity of the material of piston, piston rings, and combustion chamber wall. Results show variation of temperature, stresses, and deformation at various points on the piston.

  18. Tests of the CMS Phase 1 Upgrade FPIX Half Cylinders

    Science.gov (United States)

    Chen, Xuan; CMS Collaboration

    2017-01-01

    The pixel detector is an integral part of the CMS silicon tracker, designed to measure the position and momentum of charged particles produced in high-energy collisions at the Large Hadron Collider (LHC). The phase 1 upgrade of the CMS forward pixel detector will replace the existing forward pixel detector at the end of 2016. This upgrade will include three forward disks on each end, and is organized in four mechanical support structures, called half-cylinders. Each half-cylinder contains frontend readout electronic boards, power regulators, cables and fibers in addition to the three half disks with the active pixel modules. Full system tests are being performed on the half cylinders after each step of assembly and after its completion. I will describe the various steps of the testing and qualification procedure, focusing on the final assembly and the full system test for the integrated half-cylinder. I will also discuss the results obtained for the completed detector before its shipment to CERN.

  19. Bubbly flows around a two-dimensional circular cylinder

    Science.gov (United States)

    Lee, Jubeom; Park, Hyungmin

    2016-11-01

    Two-phase cross flows around a bluff body occur in many thermal-fluid systems like steam generators, heat exchangers and nuclear reactors. However, our current knowledge on the interactions among bubbles, bubble-induced flows and the bluff body are limited. In the present study, the gas-liquid bubbly flows around a solid circular cylinder are experimentally investigated while varying the mean void fraction from 5 to 27%. The surrounding liquid (water) is initially static and the liquid flow is only induced by the air bubbles. For the measurements, we use the high-speed two-phase particle image velocimetry techniques. First, depending on the mean void fraction, two regimes are classified with different preferential concentration of bubbles in the cylinder wake, which are explained in terms of hydrodynamic force balances acting on rising bubbles. Second, the differences between the two-phase and single-phase flows (while matching their Reynolds numbers) around a circular cylinder will be discussed in relation to effects of bubble dynamics and the bubble-induced turbulence on the cylinder wake. Supported by a Grant (MPSS-CG-2016-02) through the Disaster and Safety Management Institute funded by Ministry of Public Safety and Security of Korean government.

  20. Buckling Experiment on Anisotropic Long and Short Cylinders

    Directory of Open Access Journals (Sweden)

    Atsushi Takano

    2016-07-01

    Full Text Available A buckling experiment was performed on anisotropic, long and short cylinders with various radius-to-thickness ratios. The 13 cylinders had symmetric and anti-symmetric layups, were between 2 and 6 in terms of the length-to-radius ratio, between 154 and 647 in radius-to-thickness ratio, and made of two kinds of carbon fiber reinforced plastic (CFRP prepreg with high or low fiber modulus. The theoretical buckling loads for the cylinders were calculated from the previously published solution by using linear bifurcation theory considering layup anisotropy and transverse shear deformation and by using deep shell theory to account for the effect of length and compared with the test results. The theoretical buckling loads for the cylinders were calculated from the previously published solution by using linear bifurcation theory considering layup anisotropy and transverse shear deformation and by using deep shell theory to account for the effect of length. The knockdown factor, defined as the ratio of the experimental value to the theoretical value, was found to be between 0.451 and 0.877. The test results indicated that a large length-to-radius ratio reduces the knockdown factor, but the radius-to-thickness ratio and other factors do not affect it.

  1. Prediction of External Corrosion for Steel Cylinders--2002 Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmoyer, RLS

    2002-07-31

    The United States Department of Energy (DOE) manages the UF{sub 6} Cylinder Project. The project was formed to maintain and safely manage the depleted uranium hexafluoride (UF{sub 6}) stored in approximately 50,000 carbon steel cylinders. The cylinders are located at three DOE sites: the East Tennessee Technology Park (ETTP) site in Oak Ridge, Tennessee; the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The System Requirements Document (SRD) (LMES 1997a) delineates the requirements of the project, and the actions needed to fulfill these requirements are specified in the System Engineering Management Plan (SEMP) (LMES 1997b). This report documents activities that in whole or part satisfy specific requirements and actions stated in the UF{sub 6} Cylinder Project SRD and SEMP with respect to forecasting cylinder conditions. The results presented here supercede those presented by Lyon (1995, 1996, 1997, 1998, 2000), and Schmoyer and Lyon (2001). Many of the wall thickness projections made in this report are conservative, because they are based on the assumption that corrosion trends will continue, despite activities such as improved monitoring, relocations to better storage, painting, and other improvements in storage conditions relative to the conditions at the times most of the wall thickness measurements were made. For thin-wall cylinders (design nominal wall thickness 312.5 mils), the critical minimum wall thicknesses criteria used in this report are 0 (breach), 62.5 mils, and 250 mils (1 mil = 0.001 in.). For thick-wall cylinders (design nominal wall thickness 625 mils), the thickness criteria used in this report are 0, 62.5 mils, and 500 mils. The criteria triples are preliminary boundaries identified within the project that indicate (1) loss of material (UF{sub 6}), (2) safe handling and stacking operations, and (3) standards for off-site transport and contents transfer

  2. Coriolis effects on nonlinear oscillations of rotating cylinders and rings

    Science.gov (United States)

    Padovan, J.

    1976-01-01

    The effects which moderately large deflections have on the frequency spectrum of rotating rings and cylinders are considered. To develop the requisite solution, a variationally constrained version of the Lindstedt-Poincare procedure is employed. Based on the solution developed, in addition to considering the effects of displacement induced nonlinearity, the role of Coriolis forces is also given special consideration.

  3. 49 CFR 178.35 - General requirements for specification cylinders.

    Science.gov (United States)

    2010-10-01

    ...) The word “spun” or “plug” must be placed near the DOT specification marking when an end closure in the finished cylinder has been welded by the spinning process, or effected by plugging. (ii) As prescribed in... shoulder, top head, or neck. (5) The size of each marking must be at least 0.25 inch or as space permits...

  4. UF{sub 6} cylinder lifting equipment enhancements

    Energy Technology Data Exchange (ETDEWEB)

    Hortel, J.M. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    This paper presents numerous enhancements that have been made to the Portsmouth lifting equipment to ensure the safe handling of cylinders containing liquid uranium hexafluoride (UF{sub 6}). The basic approach has been to provide redundancy to all components of the lift path so that any one component failure would not cause the load to drop or cause any undesirable movement.

  5. Temporary patching of damaged UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas, A.L. [Martin Marietta Energy Systems, Inc., OH (United States)

    1991-12-31

    Patching techniques based on application of epoxy resins have been developed for temporarily repairing UF{sub 6} cylinders which have sustained relatively minor damage and must be safely emptied. The method is considerably faster and simpler than metallurgical weld repairs. Laboratory tests, detailed operational procedures, and case histories of experience at the Portsmouth Gaseous Diffusion Plant are described.

  6. Alternative method of retesting UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Christ, R. [Nuclear Crago + Service GmbH, Hanau (Germany)

    1991-12-31

    The paper describes an alternative method to perform the periodic inspection of UF{sub 6} cylinders. The hydraulic test is replaced by ultrasonic checking of wall thickness and by magnetic particle testing of all the weld seams. Information about the legal background, the air leak test and the qualification of inspectors is also given.

  7. Viscoelastic flow simulations through an array of cylinders

    NARCIS (Netherlands)

    Gillissen, J.J.J.

    2013-01-01

    Polymer solution flow is studied numerically in a periodic, hexagonal array of cylinders as a model for a porous medium. We use a lattice Boltzmann method supplemented by a polymer stress, where the polymers are modeled as finitely extensible, nonlinear, elastic dumbbells. The simulated, nonmonotoni

  8. Large eight.cylinder Stirling engine for biofuels

    DEFF Research Database (Denmark)

    Carlsen, Henrik; Biedermann, F.; Bovin, Jonas Kabell

    2003-01-01

    A large Stirling engine with an electric power output of 70 kW has been developed for small-scale CHP using wood chips and other sorts of biomass as fuel. The development of the engine is based on the results from the development of a four-cylinder Stirling engine with a power output of 35 kW, wh...

  9. Imperfection effects on the buckling of hydrostatically loaded cylinders

    DEFF Research Database (Denmark)

    Pinna, Rodney; Madsen, Søren

    2015-01-01

    The presence of geometric and other imperfections in cylinders has been known to result in collapse loads well below those predicted from eigenvalue analysis for a long time. As the designer's ability to routinely employ non-linear FEA has increased, the importance of modelling such imperfections...

  10. Numerical and asymptotic aspects of parabolic cylinder functions

    NARCIS (Netherlands)

    Temme, N.M.

    2000-01-01

    Several uniform asymptotics expansions of the Weber parabolic cylinder functions are considered, one group in terms of elementary functions, another group in terms of Airy functions. Starting point for the discussion are asymptotic expansions given earlier by F.W.J. Olver. Some of his results are

  11. Integral representations for computing real parabolic cylinder functions

    NARCIS (Netherlands)

    Gil, A.; Segura, J.; Temme, N.M.

    2005-01-01

    Integral representations are derived for the parabolic cylinder functions U(a,x), V(a,x) and W(a,x) and their derivatives. The new integrals will be used in numerical algorithms based on quadrature. They follow from contour integrals in the complex plane, by using methods from asymptotic analysis (s

  12. Representing plants as rigid cylinders in experiments and models

    Science.gov (United States)

    Vargas-Luna, Andrés; Crosato, Alessandra; Calvani, Giulio; Uijttewaal, Wim S. J.

    2016-07-01

    Simulating the morphological adaptation of water systems often requires including the effects of plants on water and sediment dynamics. Physical and numerical models need representing vegetation in a schematic easily-quantifiable way despite the variety of sizes, shapes and flexibility of real plants. Common approaches represent plants as rigid cylinders, but the ability of these schematizations to reproduce the effects of vegetation on morphodynamic processes has never been analyzed systematically. This work focuses on the consequences of representing plants as rigid cylinders in laboratory tests and numerical simulations. New experiments show that the flow resistance decreases for increasing element Reynolds numbers for both plants and rigid cylinders. Cylinders on river banks can qualitatively reproduce vegetation effects on channel width and bank-related processes. A comparative review of numerical simulations shows that Baptist's method that sums the contribution of bed shear stress and vegetation drag, underestimates bed erosion within sparse vegetation in real rivers and overestimates the mean flow velocity in laboratory experiments. This is due to assuming uniform flow among plants and to an overestimation of the role of the submergence ratio.

  13. The SCUBA-2 Cosmology Legacy Survey: The EGS deep field I - Deep number counts and the redshift distribution of the recovered Cosmic Infrared Background at 450 and 850 um

    CERN Document Server

    Zavala, J A; Geach, J E; Hughes, D H; Birkinshaw, M; Chapin, E; Chapman, S; Chen, Chian-Chou; Clements, D L; Dunlop, J S; Farrah, D; Ivison, R J; Jenness, T; Michałowski, M J; Robson, E I; Scott, Douglas; Simpson, J; Spaans, M; van der Werf, P

    2016-01-01

    We present deep observations at 450 um and 850 um in the Extended Groth Strip field taken with the SCUBA-2 camera mounted on the James Clerk Maxwell Telescope as part of the deep SCUBA-2 Cosmology Legacy Survey (S2CLS), achieving a central instrumental depth of $\\sigma_{450}=1.2$ mJy/beam and $\\sigma_{850}=0.2$ mJy/beam. We detect 57 sources at 450 um and 90 at 850 um with S/N > 3.5 over ~70 sq. arcmin. From these detections we derive the number counts at flux densities $S_{450}>4.0$ mJy and $S_{850}>0.9$ mJy, which represent the deepest number counts at these wavelengths derived using directly extracted sources from only blank-field observations with a single-dish telescope. Our measurements smoothly connect the gap between previous shallower blank-field single-dish observations and deep interferometric ALMA results. We estimate the contribution of our SCUBA-2 detected galaxies to the cosmic infrared background (CIB), as well as the contribution of 24 um-selected galaxies through a stacking technique, which ...

  14. Effects of GFF Bands on Normal and High Strength Concrete Cylinders

    OpenAIRE

    Jayaprakash, J; Abdul Aziz Abdul Samad; Noridah Mohamad; K.K. Choong; M.J. Megat Azmi; H.A.B. Badorul

    2010-01-01

    This paper exemplifies the effects of externally confined Glass Fibre Fabric (GFF) bands on normal and high strength concrete cylinders. Twelve normal and high strength concrete cylinders were cast and tested in the laboratory environment under axial compression to failure. The experimental results show that the degree of confinement of discrete GFF confined high strength concrete cylinders was significantly better than normal strength concrete cylinders with GFF bands, however...

  15. RELIABILITY ANALYSIS OF THE PRIMARY CYLINDER OF THE 10 MN HYDRAULIC PRESS

    Institute of Scientific and Technical Information of China (English)

    Zhao Jingyi; Zhuoru; Wang Yiqun

    2000-01-01

    According to the demand of high reliability of the primary cylinder of the hydraulic press,the reliability model of the primary cylinder is built after its reliability analysis.The stress of the primary cylinder is analyzed by finite element software-MARC,and the structure reliability of the cylinder based on stress-strength model is predicted,which would provide the reference to the design.

  16. Optimization Study on a Single-cylinder Compressed Air Engine

    Institute of Scientific and Technical Information of China (English)

    YU Qihui; CAI Maolin; SHI Yan; XU Qiyue

    2015-01-01

    The current research of compressed air engine (CAE) mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popularization. In this paper, the working principles of CAE are briefly introduced. To set a foundation for the study on the optimization of the CAE, the basic mathematical model of working processes is set up. A pressure-compensated valve which can reduce the inertia force of the valve is proposed. To verify the mathematical model, the prototype with the newly designed pressure-compensated intake valve is built and the experiment is carried out, simulation and experimental results of the CAE are conducted, and pressures inside the cylinder and output torque of the CAE are obtained. Orthogonal design and grey relation analysis are utilized to optimize structural parameters. The experimental and optimized results show that, first of all, pressure inside the cylinder has the same changing tendency in both simulation curve and experimental curve. Secondly, the highest average output torque is obtained at the highest intake pressure and the lowest rotate speed. Thirdly, the optimization of the single-cylinder CAE can improve the working efficiency from an original 21.95% to 50.1%, an overall increase of 28.15%, and the average output torque increases also increases from 22.047 5 N • m to 22.439 N • m. This research designs a single-cylinder CAE with pressure-compensated intake valve, and proposes a structural parameters design method which improves the single-cylinder CAE performance.

  17. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Science.gov (United States)

    2010-10-01

    ...) Type, size, and service pressure. A DOT 3T cylinder is a seamless steel cylinder with a minimum water... eliminate these defects provided the minimum wall thickness is maintained. (5) Welding or brazing on a cylinder is not permitted. (d) Wall thickness. The minimum wall thickness must be such that the wall...

  18. SOME OBSERVATIONS OF TWO INTERFERING VIV CIRCULAR CYLINDERS OF UNEQUAL DIAMETERS IN TANDEM

    Institute of Scientific and Technical Information of China (English)

    HUANG Shan; SWORN Andy

    2011-01-01

    Analysis of model test results was carried out to investigate the hydrodynamic interaction between a pair of elastically-supported rigid cylinders of dissimilar diameters in a water flume.The two cylinders are placed in tandem with one situated in the wake of the other.The diameter of the upstream cylinder is twice as large as that of the downstream cylinder.The spacing between the two cylinders ranges from 1 to 10 times the larger cylinder diameter.The Reynolds numbers are within the sub-critical range.The cylinders are free to oscillate in both the in-line and the cross-flow directions.The reduced velocity ranges from 1 to 10 and the low damping ratio of the model test set-up at 0.006 gives a combined m.ass-damping parameter of 0.02.It is found that the lift on and the cross-flow motion of the downstream cylinder have the frequency components derived from the upstream cylinder's vortex shedding as well as from its own vortex shedding,and the relative importance of the two sources of excitation is influenced by the spacing between the two cylinders.The downstream cylinder's VIV response appears to be largely dependent upon the actual reduced velocity of the cylinder.

  19. Formation of whispering gallery modes by scattering of an electromagnetic plane wave by two cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, Arnold, E-mail: qulaser@gmail.com [Kuang-Chi Institute of Advanced Technology, Shenzhen, 518057 (China); Kostikov, Alexander [Donbass State Engineering Academy, 84303, Kramatorsk, Donetsk (Ukraine)

    2017-03-26

    We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder. - Highlights: • We consider scattering of electromagnetic plane waves by two cylinders. • WGMs occur because of the presence of additional cylinder at specific location. • The accuracy for the locations is much less than required for specific values of single cylinder. • The interference of waves scattered by additional cylinders and incident on the main is responsible for the effect.

  20. On Uniform Motion of a Periodic System of Absolutely Rigid Stamps, in the Hollow Cylinder

    Directory of Open Access Journals (Sweden)

    Amirjanyan H. A.

    2011-03-01

    Full Text Available Axissymetric stress state of the infinite hollow cylinder when on the inner surface of the cylinder acts a periodic system of uniformly moving circular stamps and the outer surface is free of loads or rigidly clamped is considered The behavior of the contact stresses, acting under the stamp, in dependence on the physical and geometrical parameters of the cylinder is studied.

  1. 49 CFR 178.68 - Specification 4E welded aluminum cylinders.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Specification 4E welded aluminum cylinders. 178.68 Section 178.68 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... FOR PACKAGINGS Specifications for Cylinders § 178.68 Specification 4E welded aluminum cylinders....

  2. 49 CFR 178.50 - Specification 4B welded or brazed steel cylinders.

    Science.gov (United States)

    2010-10-01

    ... and a service pressure of at least 150 but not over 500 psig. Cylinders closed in by spinning process..., and valve protection rings to the tops and bottoms of cylinders by welding or brazing is authorized... permanently in any of the following locations on the cylinder: (1) On shoulders and top heads when they are...

  3. 49 CFR 178.36 - Specification 3A and 3AX seamless steel cylinders.

    Science.gov (United States)

    2010-10-01

    ... these defects. The thickness of the bottoms of cylinders welded or formed by spinning is, under no... the attachment of neckrings and footrings which are non-pressure parts and only to the tops and... test. All spun cylinders and plugged cylinders must be tested for leakage by gas or air pressure after...

  4. 49 CFR 178.37 - Specification 3AA and 3AAX seamless steel cylinders.

    Science.gov (United States)

    2010-10-01

    ... cylinders welded or formed by spinning is, under no condition, to be less than two times the minimum wall... which are non-pressure parts, and only to the tops and bottoms of cylinders having a service pressure of... required, without cracking, to 6 times the wall thickness of the cylinder. (m) Leakage test. All spun...

  5. 49 CFR 173.40 - General packaging requirements for toxic materials packaged in cylinders.

    Science.gov (United States)

    2010-10-01

    ... concrete or steel, impacting at an orientation most likely to cause damage. “Deformation”means a cylinder... packaged in cylinders. 173.40 Section 173.40 Transportation Other Regulations Relating to Transportation... Transportation § 173.40 General packaging requirements for toxic materials packaged in cylinders. When this...

  6. 49 CFR 178.59 - Specification 8 steel cylinders with porous fillings for acetylene.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Specification 8 steel cylinders with porous fillings for acetylene. 178.59 Section 178.59 Transportation Other Regulations Relating to Transportation... cylinders with porous fillings for acetylene. (a) Type and service pressure. A DOT 8 cylinder is a...

  7. 49 CFR 178.60 - Specification 8AL steel cylinders with porous fillings for acetylene.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Specification 8AL steel cylinders with porous fillings for acetylene. 178.60 Section 178.60 Transportation Other Regulations Relating to Transportation... cylinders with porous fillings for acetylene. (a) Type and service pressure. A DOT 8AL cylinder is...

  8. A numerical investigation of sub-wavelength resonances in polygonal metamaterial cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2009-01-01

    of polygonal cylinders excited by a nearby electric line current is analyzed numerically and it is shown, through detailed analysis of the near-field distribution and radiation resistance, that these polygonal cylinders do indeed support sub-wavelength resonances similar to those of the circular cylinders...

  9. Antiferromagnetic vs. non-magnetic ε phase of solid oxygen. Periodic density functional theory studies using a localized atomic basis set and the role of exact exchange.

    Science.gov (United States)

    Ramírez-Solís, A; Zicovich-Wilson, C M; Hernández-Lamoneda, R; Ochoa-Calle, A J

    2017-01-25

    The question of the non-magnetic (NM) vs. antiferromagnetic (AF) nature of the ε phase of solid oxygen is a matter of great interest and continuing debate. In particular, it has been proposed that the ε phase is actually composed of two phases, a low-pressure AF ε1 phase and a higher pressure NM ε0 phase [Crespo et al., Proc. Natl. Acad. Sci. U. S. A., 2014, 111, 10427]. We address this problem through periodic spin-restricted and spin-polarized Kohn-Sham density functional theory calculations at pressures from 10 to 50 GPa using calibrated GGA and hybrid exchange-correlation functionals with Gaussian atomic basis sets. The two possible configurations for the antiferromagnetic (AF1 and AF2) coupling of the 0 ≤ S ≤ 1 O2 molecules in the (O2)4 unit cell were studied. Full enthalpy-driven geometry optimizations of the (O2)4 unit cells were done to study the pressure evolution of the enthalpy difference between the non-magnetic and both antiferromagnetic structures. We also address the evolution of structural parameters and the spin-per-molecule vs. pressure. We find that the spin-less solution becomes more stable than both AF structures above 50 GPa and, crucially, the spin-less solution yields lattice parameters in much better agreement with experimental data at all pressures than the AF structures. The optimized AF2 broken-symmetry structures lead to large errors of the a and b lattice parameters when compared with experiments. The results for the NM model are in much better agreement with the experimental data than those found for both AF models and are consistent with a completely non-magnetic (O2)4 unit cell for the low-pressure regime of the ε phase.

  10. Experiments on Sphere Cylinder Geometry Dependence in the Electromagnetic Casimir Effect

    Science.gov (United States)

    Mukhopadhyay, Shomeek; Noruzifar, Ehsan; Wagner, Jeffrey; Zandi, Roya; Mohideen, Umar

    2013-03-01

    We report on ongoing experimental investigations on the geometry dependence of the electromagnetic Casimir force in the sphere-cylinder configuration. A gold coated hollow glass sphere which forms one surface is attached to a Silicon AFM cantilever. The cylinder, which is constructed from tapered optical fiber is also gold coated. The resonance frequency shift of the cantilever is measured as a function of the sphere-cylinder surface separation. The sphere-cylinder electrostatic force is used for alignment of the sphere and the cylinder and also for calibrating the system. The results are compared to numerical simulations in the framework of the Proximity Force Approximation (PFA).

  11. Influence of ventilated shrouds on the convective heat transfer to a circular cylinder

    Science.gov (United States)

    Daryabeigi, Kamran; Ash, Robert L.; Dillon-Townes, Lawrence A.

    1987-01-01

    Convective heat transfer to shrouded cylinders in transverse flow has been studied over the Reynolds number range 2000-20,000. The influence of shroud ventilation, relative shroud diameters, and orientation of the ventilation holes was studied. In some cases, average inner-cylinder Nusselt numbers were found to exceed the comparable bare-cylinder values by as much as 50 percent. Cylinder heat convection was influenced more by the degree of ventilation and shroud diameter than by hole orientation. An equivalent inner bare cylinder diameter, based on degree of shroud ventilation and shroud diameter, was developed which can be useful in shroud design studies.

  12. The SCUBA Half-Degree Extragalactic Survey (SHADES) - VIII. The Nature of Faint Submm Galaxies in SHADES, SWIRE and SXDF Surveys

    CERN Document Server

    Clements, D L; Babbedge, T; Oliver, S; Rowan-Robinson, M; Davoodi, P; Ivison, R; Farrah, D; Dunlop, J; Shupe, Dave; Waddington, I; Simpson, C; Furusawa, H; Serjeant, S; Afonso-Luis, A; Alexander, D M; Aretxaga, I; Blain, A; Borys, C; Chapman, S; Coppin, K; Dunne, L; Dye, S; Eales, S A; Evans, T; Fang, F; Frayer, D; Fox, M; Gear, W K; Greve, T R; Halpern, M; Hughes, D H; Jenness, T; Lonsdale, C J; Mortier, A M J; Page, M J; Pope, A; Priddey, R S; Rawlings, S; Savage, R S; Scott, D; Scott, S E; Sekiguchi, K; Smail, I; Smith, H E; Stevens, J A; Surace, J; Takagi, T; Van Kampen, E

    2008-01-01

    We present the optical-to-submm spectral energy distributions for 33 radio & mid-IR identified submillimetre galaxies discovered via the SHADES 850 micron SCUBA imaging in the Subaru-XMM Deep Field (SXDF). Optical data for the sources comes from the Subaru-XMM Deep Field (SXDF) and mid- and far-IR fluxes from SWIRE. We obtain photometric redshift estimates for our sources using optical and IRAC 3.6 and 4.5 micron fluxes. We then fit spectral energy distribution (SED) templates to the longer wavelength data to determine the nature of the far-IR emission that dominates the bolometric luminosity of these sources. The infrared template fits are also used to resolve ambiguous identifications and cases of redshift aliasing. The redshift distribution obtained broadly matches previous results for submm sources and on the SHADES SXDF field. Our template fitting finds that AGN, present in about 10% of sources, do not contribute significantly to their bolometric luminosity. Dust heating by starbursts, with either Ar...

  13. A SCUBA-2 survey of FeLoBAL QSOs: Are FeLoBALs in a `transition phase' between ULIRGs and QSOs?

    CERN Document Server

    Violino, Giulio; Stevens, Jason A; Farrah, Duncan; Geach, James E; Alexander, Dave M; Hickox, Ryan; Smith, Daniel J B; Wardlow, Julie L

    2015-01-01

    It is thought that a class of broad absorption line (BAL) QSOs, characterised by Fe absorption features in their UV spectra (called `FeLoBALs'), could mark a transition stage between the end of an obscured starburst event and a youthful QSO beginning to shed its dust cocoon, where Fe has been injected into the interstellar medium by the starburst. To test this hypothesis we have undertaken deep SCUBA-2 850 $\\mu$m observations of a sample of 17 FeLoBAL QSOs with 0.89 $\\leq$ z $\\leq$ 2.78 and -23.31 $\\leq$ M$_{B}$ $\\leq$-28.50 to directly detect an excess in the thermal emission of the dust which would probe enhanced star-formation activity. We find that FeLoBALs are not luminous sources in the submillimetre, none of them are individually detected at 850 $\\mu$m, nor as a population through stacking ($F_{s}=1.14\\pm0.58$ mJy). Statistical and survival analyses reveal that FeLoBALs have sub-mm properties consistent with BAL and non-BAL QSOs with matched redshifts and magnitudes. An SED fitting analysis shows that ...

  14. Cold Dust Emission from X-ray AGN in the SCUBA-2 Cosmology Legacy Survey: Dependence on Luminosity, Obscuration & AGN Activity

    CERN Document Server

    Banerji, Manda; Willott, C J; Geach, J E; Harrison, C M; Alaghband-Zadeh, S; Alexander, D M; Bourne, N; Coppin, K E K; Dunlop, J S; Farrah, D; Jarvis, M; Michalowski, M J; Page, M; Smith, D J B; Swinbank, A M; Symeonidis, M; Van der Werf, P P

    2015-01-01

    We study the 850um emission in X-ray selected AGN in the 2 sq-deg COSMOS field using new data from the SCUBA-2 Cosmology Legacy Survey. We find 19 850um bright X-ray AGN in a high-sensitivity region covering 0.89 sq-deg with flux densities of S850=4-10 mJy. The 19 AGN span the full range in redshift and hard X-ray luminosity covered by the sample - 0.71 X-ray AGN - S850=0.71+/-0.08mJy. We explore trends in the stacked 850um flux densities with redshift, finding no evolution in the average cold dust emission over the redshift range probed. For Type 1 AGN, there is no significant correlation between the stacked 850um flux and hard X-ray luminosity. However, in Type 2 AGN the stacked submm flux is a factor of 2 higher at high luminosities. When averaging over all X-ray luminosities, no significant differences are found in the stacked submm fluxes of Type 1 and Type 2 AGN as well as AGN separated on the basis of X-ray hardness ratios and optical-to-infrared colours. However, at log10(LX) >44.4, dependences in ave...

  15. An Approach to Stability Analysis of Embedded Large-Diameter Cylinder Quay

    Institute of Scientific and Technical Information of China (English)

    王元战; 祝振宇

    2002-01-01

    The large-diameter cylinder structure, which is made of large successive bottomless cylinders placed on foundationbed or partly driven into soil, is a recently developed retaining structure in China. It can be used in port, coastal and off-shore works. The method for stability analysis of the large-diameter cylinder structure, especially for stability analysis ofthe embedded large-diameter cylinder structure, is an important issue. In this paper, an idea is presented that is, em-bedded large-diameter cylinder quays can be divided into two types, i.e. the gravity wall type and the cylinder pile walltype. A method for stability analysis of the large-diameter cylinder quay of the cylinder pile wall type is developed and amethod for stability analysis of the large-diameter cylinder quay of the gravity wall type is also proposed. The effect of sig-nificant parameters on the stability of the large-dianeter cylinder quay of the cylinder pile wall type is investigated throughnumerical calculation.

  16. Acoustic band gaps in two-dimensional square arrays of semi-hollow circular cylinders

    Institute of Scientific and Technical Information of China (English)

    T.; Kim

    2009-01-01

    Concave surfaces focus sound while convex surfaces disperse sound. It is therefore interesting to know if it is possible to make use of these two opposite characteristics to enhance the band gap performance of periodic arrays of solid cylinders in air. In this paper, the band gap characteristics of a 2-D square array of semi-hollow circular cylinders embedded in air are investigated, both experimentally and theoretically. In comparison with the types of inclusion studied by previous researchers, a semi-hollow circular cylinder is unique in the sense that it has concave inner surfaces and convex outer surfaces. The finite difference time domain (FDTD) method is employed to study the propagation behavior of sound across the new phononic crystal of finite extent, and the influences of sample size and inclusion orientation on band gap characteristics are quantified in order to obtain the maximum band gap. For reference, the band gap behaviors of solid circular cylinder/air and hollow circular cylinder/air systems are considered and compared with those of semi-hollow circular cylinder/air systems. In addition to semi-hollow circular cylinders, other inclusion topologies such as semi-hollow triangular and square cylinders are also investigated. To validate the theoretical predictions, experimental measurements on square arrays of hollow Al cylinders in air and semi-hollow Al cylinders in air are carried out. The results demonstrate that the semi-hollow circular cylinder/air system has the best overall band gap performance.

  17. Flow characteristics of the two tandem wavy cylinders and drag reduction phe-nomenon

    Institute of Scientific and Technical Information of China (English)

    邹琳; 郭丛波; 熊灿

    2013-01-01

    This paper presents an extensive numerical study of 3-D laminar flow around two wavy cylinders in the tandem arrangement for spacing ratios (L/Dm ) ranging from 1.5 to 5.5 at a low Reynolds number of 100. The investigation focuses on the effects of spacing ratio (L/Dm ) and wavy surface on the 3-D near wake flow patterns, the force and pressure coefficients and the vortex shedding frequency for the two tandem wavy cylinders. Flows around the two tandem circular cylinders are also obtained for comparison. With the spacing ratio in the range of L/Dm=1.5-5.5 , unlike two tandem circular cylinders, the wavy cylinders in the tandem arrangement do not have the wake interference behaviour of three basic types. The vortex shedding behind the upstream wavy cylinder occurs at a further downstream position as compared with that of the upstream circular cylinder. This leads to the weakening of the effect of the vibration of the cylinders as well as a distinct drag reduction. The effects of the drag reduction and the control of the vibration of the two wavy cylinders in tandem become more and more evident when L/Dm³4.0, with a distinct vortex shedding in the upstream cylinder regime for the two circular cylinders in tandem.

  18. Control of mean and fluctuating forces on a circular cylinder at high Reynolds numbers

    Institute of Scientific and Technical Information of China (English)

    Chuanping Shao; Jianming Wang

    2007-01-01

    A narrow strip is used to control mean and fluctuating forces on a circular cylinder at Reynolds numbers from 2.0 x 104 to 1.0 x 105. The axes of the strip and cylinder are parallel. The control parameters are strip width ratio and strip position characterized by angle of attack and distance from the cylinder. Wind tunnel tests show that the vortex shedding from both sides of the cylinder can be suppressed, and mean drag and fluctuating lift on the cylinder can be reduced if the strip is installed in an effective zone downstream of the cylinder. A phenomenon of mono-side vortex shedding is found. The strip-induced local changes of velocity profiles in the near wake of the cylinder are measured, and the relation between base suction and peak value in the power spectrum of fluctuating lift is studied. The control mechanism is then discussed from different points of view.

  19. Effect of Catalytic Cylinders on Autothermal Reforming of Methane for Hydrogen Production in a Microchamber Reactor

    Directory of Open Access Journals (Sweden)

    Yunfei Yan

    2014-01-01

    Full Text Available A new multicylinder microchamber reactor is designed on autothermal reforming of methane for hydrogen production, and its performance and thermal behavior, that is, based on the reaction mechanism, is numerically investigated by varying the cylinder radius, cylinder spacing, and cylinder layout. The results show that larger cylinder radius can promote reforming reaction; the mass fraction of methane decreased from 26% to 21% with cylinder radius from 0.25 mm to 0.75 mm; compact cylinder spacing corresponds to more catalytic surface and the time to steady state is decreased from 40 s to 20 s; alteration of staggered and aligned cylinder layout at constant inlet flow rates does not result in significant difference in reactor performance and it can be neglected. The results provide an indication and optimize performance of reactor; it achieves higher conversion compared with other reforming reactors.

  20. Effect of catalytic cylinders on autothermal reforming of methane for hydrogen production in a microchamber reactor.

    Science.gov (United States)

    Yan, Yunfei; Guo, Hongliang; Zhang, Li; Zhu, Junchen; Yang, Zhongqing; Tang, Qiang; Ji, Xin

    2014-01-01

    A new multicylinder microchamber reactor is designed on autothermal reforming of methane for hydrogen production, and its performance and thermal behavior, that is, based on the reaction mechanism, is numerically investigated by varying the cylinder radius, cylinder spacing, and cylinder layout. The results show that larger cylinder radius can promote reforming reaction; the mass fraction of methane decreased from 26% to 21% with cylinder radius from 0.25 mm to 0.75 mm; compact cylinder spacing corresponds to more catalytic surface and the time to steady state is decreased from 40 s to 20 s; alteration of staggered and aligned cylinder layout at constant inlet flow rates does not result in significant difference in reactor performance and it can be neglected. The results provide an indication and optimize performance of reactor; it achieves higher conversion compared with other reforming reactors.

  1. Cracked lifting lug welds on ten-ton UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Dorning, R.E. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    Ten-ton, Type 48X, UF{sub 6} cylinders are used at the Portsmouth Gaseous Diffusion Plant to withdraw enriched uranium hexafluoride from the cascade, transfer enriched uranium hexafluoride to customer cylinders, and feed enriched product to the cascade. To accomplish these activities, the cylinders are lifted by cranes and straddle carriers which engage the cylinder lifting lugs. In August of 1988, weld cracks on two lifting lugs were discovered during preparation to lift a cylinder. The cylinder was rejected and tagged out, and an investigating committee formed to determine the cause of cracking and recommend remedial actions. Further investigation revealed the problem may be general to this class of cylinder in this use cycle. This paper discusses the actions taken at the Portsmouth site to deal with the cracked lifting lug weld problem. The actions include inspection activities, interim corrective actions, metallurgical evaluation of cracked welds, weld repairs, and current monitoring/inspection program.

  2. Flow Features of Three Side-by-side Circular Cylinders at Low Reynolds Number

    Directory of Open Access Journals (Sweden)

    Liu Junkao

    2016-01-01

    Full Text Available In order to study the fluctuation of kinetic parameter of cylinder matrix in incompressible stationary flow, the flow fluid around three side-by-side circular cylinders are simulated using Immersed Boundary–Lattice Boltzmann method (IB-LBM. Drag and lift force of the three cylinders are investigated as the interval between each cylinder varied from zero to five times of the cylinder diameter. Five flow patterns are defined according to the vortices structure in the downstream of the cylinders. Power spectrum analysis of lift force is developed to explain the vortex patterns. Through the research, we find the strength and phase of the gap flow play an important role in the vortex formatting process. The vortices shedding from different cylinders neutralize and combine in the near wake, contributing a lot to the variation of forces.

  3. Numerical simulation of design for cylinder wall considering of scavenging efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, S.; Ezumi, T.; Satoh, K. [Dept. of Mechanical Eng., Shibaura Inst. of Tech., Tokyo (Japan)

    2004-07-01

    The transformation of the cylinder is examined and analyzed the pressure and the temperature by means of the numerical analysis under the change of the scavenging efficiency. The change of the scavenging efficiency makes the temperature and the pressure change. The combustion temperature of the 2-cycle internal combustion engine that a lot of fuels may burn in the cylinder when the scavenging efficiency goes up. According to the scavenging efficiency, the temperature and the pressure is getting high. So the cylinder is transformed under the high temperature and the high pressure. The authors simulated the change of the temperature and the pressure in the cylinder. When the cylinder is designed, the engineer must know the change of the state in the cylinder. Then the change of the scavenging efficiency was simulated and examined. At the same time, the NO gas generated. The authors examined the transformation of the cylinder and simulated the NO generation. (orig.)

  4. Induced charge electrophoresis of a conducting cylinder in a nonconducting cylindrical pore and its micromotoring application

    Science.gov (United States)

    Feng, Huicheng; Wong, Teck Neng; Che, Zhizhao

    2016-08-01

    Induced charge electrophoresis of a conducting cylinder suspended in a nonconducting cylindrical pore is theoretically analyzed and a micromotor is proposed that utilizes the cylinder rotation. The cylinder velocities are analytically obtained in the Dirichlet and the Neumann boundary conditions of the electric field on the cylindrical pore. The results show that the cylinder not only translates but also rotates when it is eccentric with respect to the cylindrical pore. The influences of a number of parameters on the cylinder velocities are characterized in detail. The cylinder trajectories show that the cylinder approaches and becomes stationary at certain positions within the cylindrical pore. The proposed micromotor is capable of working under a heavy load with a high rotational velocity when the eccentricity is large and the applied electric field is strong.

  5. Wave Diffraction from A Vertical Cylinder with Two Uniform Columns and Porous Outer Wall

    Institute of Scientific and Technical Information of China (English)

    TFNG Rin; HAN Ling; LI Yucheng

    2000-01-01

    Based on a linear model of the pressure difference between two sides of a porous wall and the fluid velocity inside it, an analytic solution is established for wave diffraction from a cylinder with an outer porous column and an inner solid column. Numerical experiments are carried out to examine the effects of the wave force on a porous tow-column cylinder and the wave elevations outside and inside the cylinder due to the porous character of the outer column and the ratio between the radii of the inner and outer columns. The numerical results show that the increase in the coefficient of porosity of the outer column of a double column cylinder will reduce the wave elevation around the cylinder and the wave load on it. The radius of the inner column does not affect too much the wave elevation around the cylinder and the total force on the cylinder.

  6. Effect of plasma actuator and splitter plate on drag coefficient of a circular cylinder

    Directory of Open Access Journals (Sweden)

    Akbıyık Hürrem

    2016-01-01

    Full Text Available In this paper, an experimental study on flow control around a circular cylinder with splitter plate and plasma actuator is investigated. The study is performed in wind tunnel for Reynolds numbers at 4000 and 8000. The wake region of circular cylinder with a splitter plate is analyzed at different angles between 0 and 180 degrees. In this the study, not only plasma actuators are activated but also splitter plate is placed behind the cylinder. A couple electrodes are mounted on circular cylinder at ±90 degrees. Also, flow visualization is achieved by using smoke wire method. Drag coefficient of the circular cylinder with splitter plate and the plasma actuator are obtained for different angles and compared with the plain circular cylinder. While attack angle is 0 degree, drag coefficient is decreased about 20% by using the splitter plate behind the circular cylinder. However, when the plasma actuators are activated, the improvement of the drag reduction is measured to be 50%.

  7. Proposal for the award of a contract for the supply of austenitic steel strips for non-magnetic laminations of the LHC superconducting dipole magnets

    CERN Document Server

    1999-01-01

    This document concerns the award of a contract for the supply of 2 400 tonnes of cold-rolled austenitic steel strips for non-magnetic laminations of the cold mass of the LHC superconducting dipole magnets. Following a market survey carried out among 32 firms in fourteen Member States and two firms in Japan, a call for tenders (IT-2617/LHC/LHC) was sent on 3 June 1999 to three firms in two Member States and two firms in Japan. The Council agreed to the Management?s proposal to invite Japanese industry to participate, where appropriate, in calls for tenders for supplies for the LHC Project (CERN/CC/2110). By the closing date, CERN had received four tenders. The Finance Committee is invited to approve the negotiation of a contract with the firm KAWASAKI STEEL (JP), the lowest bidder complying with the technical specification, for the supply of 2 400 tonnes of cold-rolled austenitic steel for non-magnetic laminations of the cold mass of the LHC superconducting dipole magnets for a total amount of 1 277 856 000 Ja...

  8. Magnetism without magnetic ions in non-magnetic perovskites SrTiO 3, SrZrO 3 and SrSnO 3

    Science.gov (United States)

    Bannikov, V. V.; Shein, I. R.; Kozhevnikov, V. L.; Ivanovskii, A. L.

    Using the full-potential linearized augmented plane-wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential, we studied spin polarization induced by replacement of oxygen atoms by non-magnetic 2p impurities (B, C and N) in non-magnetic cubic SrMO 3 perovskites, where M=Ti, Zr and Sn. The results show that the magnetization may appear because of the spin-split impurity bands inside the energy gap of the insulating SrMO 3 matrix. Large magnetic moments are found for the impurity centers. Smaller magnetic moments are induced on the oxygen atoms around impurities. It is shown that SrTiO 3:C and SrSnO 3:C should be magnetic semiconductors while other compounds in this series (SrTiO 3:B, SrTiO 3:N and SrZrO 3:C) are expected to exhibit magnetic half-metallic or pseudo-half-metallic properties.

  9. Magnetism without magnetic ions in non-magnetic perovskites SrTiO{sub 3}, SrZrO{sub 3} and SrSnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bannikov, V.V.; Shein, I.R.; Kozhevnikov, V.L. [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620041 Ekaterinburg (Russian Federation); Ivanovskii, A.L. [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620041 Ekaterinburg (Russian Federation)], E-mail: ivanovskii@ihim.uran.ru

    2008-03-15

    Using the full-potential linearized augmented plane-wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential, we studied spin polarization induced by replacement of oxygen atoms by non-magnetic 2p impurities (B, C and N) in non-magnetic cubic SrMO{sub 3} perovskites, where M=Ti, Zr and Sn. The results show that the magnetization may appear because of the spin-split impurity bands inside the energy gap of the insulating SrMO{sub 3} matrix. Large magnetic moments are found for the impurity centers. Smaller magnetic moments are induced on the oxygen atoms around impurities. It is shown that SrTiO{sub 3}:C and SrSnO{sub 3}:C should be magnetic semiconductors while other compounds in this series (SrTiO{sub 3}:B, SrTiO{sub 3}:N and SrZrO{sub 3}:C) are expected to exhibit magnetic half-metallic or pseudo-half-metallic properties.

  10. Casimir Energy of a Semi-Circular Infinite Cylinder

    CERN Document Server

    Nesterenko, V V; Scarpetta, G

    2001-01-01

    The Casimir energy of a semi-circular cylindrical shell is calculated by making use of the zeta function technique. This shell is obtained by crossing an infinite circular cylindrical shell by a plane passing through the symmetry axes of the cylinder and by considering only a half of this configuration. All the surfaces, including the cutting plane, are assumed to be perfectly conducting. The zeta functions for scalar massless fields obeying the Dirichlet and Neumann boundary conditions on the semi-circular cylinder are constructed exactly. The sum of these zeta functions gives the zeta function for electromagnetic field in question. The relevant plane problem is considered also. In all the cases the final expressions for the corresponding Casimir energies contain the pole contributions. This implies that further renormalization is needed in order for the finite physical values for vacuum energy to be obtained for given boundary conditions.

  11. Casimir energy of a semi-circular infinite cylinder

    Science.gov (United States)

    Nesterenko, V. V.; Lambiase, G.; Scarpetta, G.

    2001-05-01

    The Casimir energy of a semi-circular cylindrical shell is calculated by making use of the zeta function technique. This shell is obtained by crossing an infinite circular cylindrical shell by a plane passing through the symmetry axes of the cylinder and by considering only half of this configuration. All the surfaces, including the cutting plane, are assumed to be perfectly conducting. The zeta functions for scalar massless fields obeying the Dirichlet and Neumann boundary conditions on the semi-circular cylinder are constructed exactly. The sum of these zeta functions gives the zeta function for the electromagnetic field in question. The relevant plane problem is considered also. In all the cases the final expressions for the corresponding Casimir energies contain the pole contributions which are the consequence of the edges or corners in the boundaries. This implies that further renormalization is needed in order for the finite physical values for vacuum energy to be obtained for given boundary conditions.

  12. Integrated two-cylinder liquid piston Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd, E-mail: todd.sulchek@me.gatech.edu [George W. Woodruff School of Mechanical Engineering and Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2014-10-06

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  13. Broadband computation of the scattering coefficients of infinite arbitrary cylinders.

    Science.gov (United States)

    Blanchard, Cédric; Guizal, Brahim; Felbacq, Didier

    2012-07-01

    We employ a time-domain method to compute the near field on a contour enclosing infinitely long cylinders of arbitrary cross section and constitution. We therefore recover the cylindrical Hankel coefficients of the expansion of the field outside the circumscribed circle of the structure. The recovered coefficients enable the wideband analysis of complex systems, e.g., the determination of the radar cross section becomes straightforward. The prescription for constructing such a numerical tool is provided in great detail. The method is validated by computing the scattering coefficients for a homogeneous circular cylinder illuminated by a plane wave, a problem for which an analytical solution exists. Finally, some radiation properties of an optical antenna are examined by employing the proposed technique.

  14. Buckling analysis of a ring stiffened hybrid composite cylinder

    Science.gov (United States)

    Potluri, Rakesh; Eswara Kumar, A.; Navuri, Karteek; Nagaraju, M.; Mojeswara Rao, Duduku

    2016-09-01

    This study aims to understand the response of the ring stiffened cylinders made up of hybrid composites subjected to buckling loads by using the concepts of Design of Experiments (DOE) and optimization by using Finite Element Method (FEM) simulation software Ansys workbench V15. Carbon epoxy and E-glass epoxy composites were used in the hybrid composite. This hybrid composite was analyzed by using different layup angles. Central composite design (CCD) was used to perform design of experiments (D.O.E) and kriging method was used to generate a response surface. The response surface optimization (RSO) was performed by using the method of the multi-objective genetic algorithm (MOGA). After optimization, the best candidate was chosen and applied to the ring stiffened cylinder and eigenvalue buckling analysis was performed to understand the buckling behavior. Best laminate candidates with high buckling strength have been identified. A generalized procedure of the laminate optimization and analysis have been shown.

  15. Two cylinder permanent magnet stirrer for liquid metals

    Science.gov (United States)

    Bojarevičs, A.; Baranovskis, R.; Kaldre, I.; Milgrāvis, M.; Beinerts, T.

    2017-07-01

    To achieve a uniform liquid metal composition and temperature distribution, stirring is often necessary for industrial processes. Here, a novel permanent magnet system for liquid melt stirring is proposed. It promises very low energy consumption and options for multiple different flow types compared to traditional travelling magnetic field inductors or mechanical stirrers. The proposed system has a simple design: it consists of two rotating permanent magnet cylinders, which are magnetized transversely to the axis of the cylinders. The experimental device was developed and tested under various regimes using GaInSn alloy in a cylindrical crucible. Aluminum stirring by permanent magnets in laboratory scale is tested, and stirring impact on directional solidification of metallic alloys is experimentally investigated.

  16. OPAL Forward Calorimeter (half cylinder with lead scintillator)

    CERN Multimedia

    1 half cylinder piece is available for loan. The OPAL forward Detector Calorimeter was made in 4 half cylindrical pieces. Two full cylinders were placed round the LEP beam pipe about 3m downstream of the interaction point. The detector was used primarily to measure the luminosity of LEP (rate of interactions) and also to trigger on 2-photon events. In addition it formed an essential part of the detector coverage which OPAL needed to carry out searches for new particles such as the Higgs boson. The detector is made of scintillators sandwiched between lead sheets. The light from the scintillators passes via bars of wavelength shifter and light guides on its way to be measured by photomultipliers. There is a layer of gas filled tube chambers within the calorimeter. These provide a measure of the position of the particles interacting in the calorimeter.

  17. Triadic instability of a non-resonant precessing fluid cylinder

    CERN Document Server

    Lagrange, R; Eloy, C

    2015-01-01

    Flows forced by a precessional motion can exhibit instabilities of crucial importance, whether they concern the fuel of a flying object or the liquid core of a telluric planet. So far, stability analyses of these flows have focused on the special case of a resonant forcing. Here, we address the instability of the flow inside a precessing cylinder in the general case. We first show that the base flow forced by the cylinder precession is a superposition of a vertical or horizontal shear flow and an infinite sum of forced modes. We then perform a linear stability analysis of this base flow by considering its triadic resonance with two free Kelvin modes. Finally, we derive the amplitude equations of the free Kelvin modes and obtain an expression of the instability threshold and growth rate.

  18. Electromagnetoelastic behaviors of functionally graded piezoelectric solid cylinder and sphere

    Institute of Scientific and Technical Information of China (English)

    H.L.Dai; Y.M.Fu; J.H.Yang

    2007-01-01

    Analytical studies on electromagnetoelasticbehaviors are presented for the functionally graded pie-zoelectric material (FGPM) solid cylinder and sphereplaced in a uniform magnetic field and subjected tothe external pressure and electric loading.When themechanical,electric and magnetic properties of thematerial obey an identical power law in the radial direc-tion,the exact displacements,stresses,electric potentialsand perturbations of magnetic field vector in the FGPMsolid cylinder and sphere are obtained by using the infin-itesimal theory of electromagnetoelasticity.Numericalexamples also show the significant influence of materialinhomogeneity.It is interesting to note that selecting aspecific value of inhomogeneity parameter β can opti-mize the electromagnetoelastic responses,which willbe of particular importance in modern engineering designs.

  19. Circular cylinders and pressure vessels stress analysis and design

    CERN Document Server

    Vullo, Vincenzo

    2014-01-01

    This book provides comprehensive coverage of stress and strain analysis of circular cylinders and pressure vessels, one of the classic topics of machine design theory and methodology. Whereas other books offer only a partial treatment of the subject and frequently consider stress analysis solely in the elastic field, Circular Cylinders and Pressure Vessels broadens the design horizons, analyzing theoretically what happens at pressures that stress the material beyond its yield point and at thermal loads that give rise to creep. The consideration of both traditional and advanced topics ensures that the book will be of value for a broad spectrum of readers, including students in postgraduate, and doctoral programs and established researchers and design engineers. The relations provided will serve as a sound basis for the design of products that are safe, technologically sophisticated, and compliant with standards and codes and for the development of innovative applications.

  20. Experimental investigation of axially aligned flow past spinning cylinders

    Science.gov (United States)

    Carlucci, Pasquale; Buckley, Liam; Mehmedagic, Igbal; Carlucci, Donald; Thangam, Siva

    2016-11-01

    Experimental and numerical results of ongoing subsonic investigations of the flow field about axially aligned spinning cylinders with variable inter-cylinder spacing are presented. The experimental design is capable of investigating wake dynamics of the modeled system up to a Reynolds Number of 300,000 and rotation numbers up to 2. The experimental results are used to validate and confirm numerical simulations with and without the effects of swirl. The focus of the overall effort is an understanding of the dynamics of multi-body problems in a flow field, as such we relate the ongoing effort to previous studies by both the authors and the community at large and our ongoing work in developing accurate plant models for use in engineering analysis and design. Funded in part by U. S. Army ARDEC, Picatinny Arsenal, NJ.