Experimental investigation of the Peregrine Breather of gravity waves on finite water depth

NASA Astrophysics Data System (ADS)

Dong, G.; Liao, B.; Ma, Y.; Perlin, M.

2018-06-01

A series of laboratory experiments were performed to study the Peregrine Breather (PB) evolution in a wave flume of finite depth and deep water. Experimental cases were selected with water depths k0h (k0 is the wave number and h is the water depth) varying from 3.11 to 8.17 and initial steepness k0a0 (a0 is the background wave amplitude) in the range 0.06 to 0.12, and the corresponding initial Ursell number in the range 0.03 to 0.061. Experimental results indicate that the water depth plays an important role in the formation of the extreme waves in finite depth; the maximum wave amplification of the PB packets is also strongly dependent on the initial Ursell number. For experimental cases with the initial Ursell number larger than 0.05, the maximum crest amplification can exceed three. If the initial Ursell number is nearly 0.05, a shorter propagation distance is needed for maximum amplification of the height in deeper water. A time-frequency analysis using the wavelet transform reveals that the energy of the higher harmonics is almost in-phase with the carrier wave. The contribution of the higher harmonics to the extreme wave is significant for the cases with initial Ursell number larger than 0.05 in water depth k0h < 5.0. Additionally, the experimental results are compared with computations based on both the nonlinear Schrödinger (NLS) equation and the Dysthe equation, both with a dissipation term. It is found that both models with a dissipation term can predict the maximum amplitude amplification of the primary waves. However, the Dysthe equation also can predict the group horizontal asymmetry.

National Dam Safety Program. Ursel Gingerich Dam (MO 10393), Mississippi - Salt - Quincy River Basin, Schuyler County, Missouri. Phase I Inspection Report.

DTIC Science & Technology

1979-12-01

34 which identifies the program element, project, task area, and work unit or equivalent under which the work was authorized. Block 11. Controlling ...Dam Inventory and Inspection Section, LMSED-PD ULSF 210 Tucker Blvd., North, St. Louis, Mo. 63101D C O 11. CONTROLLING OFFICE NAME AND ADDRESS 12m...under the National Program of Inspection of Non -Federal Dams. This report assesses the general condition of the dam with a respect to safety, based on

Recurrence in truncated Boussinesq models for nonlinear waves in shallow water

NASA Technical Reports Server (NTRS)

Elgar, Steve; Freilich, M. H.; Guza, R. T.

1990-01-01

The rapid spatial recurrence of weakly nonlinear and weakly dispersive progressive shallow-water waves is examined using a numerical integration technique on the discretized and truncated form of the Boussinesq equations. This study primarily examines recurrence in wave fields with Ursell number O(1) and characterizes the sensitivity of recurrence to initial spectral shape and number of allowed frequency modes. It is shown that the rapid spatial recurrence is not an inherent property of the considered Boussinesq systems for evolution distances of 10-50 wavelengths. The main result of the study is that highly truncated Boussinesq models of resonant shallow-water ocean surface gravity waves predict rapid multiple recurrence cycles, but that this is an artifact dependent on the number of allowed modes. For initial conditions consisting of essentially all energy concentrated in a single mode, damping of the recurrence cycles increases as the number of low-power background modes increases. When more than 32 modes are allowed, the recurrence behavior is relatively insensitive to the number of allowed modes.

Self-organising of wave and beach relief in storm: field experiments

NASA Astrophysics Data System (ADS)

Kuznetsova, Olga; Saprykina, Yana; Kuznetsov, Sergey; Stremel, Margarita; Korsinin, Dmitry; Trifonova, Ekaterina; Andreeva, Natalia

2017-04-01

This paper presents results of waves and morfodynamics observation carried out in frame of complex field experiments "Shkorpilowtsy-2016" and "Shkorpilowtsy-2007", which were made in order to understand how bottom deformations depend on wave parameters and how wave-bottom self-organisation process runs during storm events. Sediment transport and profile deformations were analysed taking into account the presence of underwater bar (data 2007) and without it (data 2016). Experiments were made on field base of Institute of Oceanology "Fridtjof Nansen" (Bulgarian Academy of Sciences) in Shkorpilowtsy settlement, that is locates on Black Sea coast, 40 km from Varna. The base is equipped with 253 m research pier that provide measuring until 5 m depth on distance 200 m from shore. During filed works synchronous observations on wave parameters and bottom changes were made on average three times a day for one month: 18.09-08.10.2007 and 07.10-02.11.2016. Morphological observations involved cross-shore beach profile deformations measuring along the scientific pier from shore to sea through each 2 m using metal pole in 2007 and metal or rope lot in 2016. Wave measurements included visual observations of breaking and surf zones location, wave type (wind or swell wave) and direction as well as free surface deviation (wave chronogram) registrations using high-frequency capacitive or resistance sensors mounted along the pier. In 2007 registration of free surface elevation was carried out with 7 capacitance and 8 resistant wire gauges, in 2016 - with 18 capacitance wire gauges. Sampling frequency was 5 Hz in 2007 and 20 Hz in 2016, duration of the records varied from 20 min up to one hour in 2007 and between 10 min and one hour in 2016. Wave spectra computed from chronogram allowed to estimate wave spectral (significant wave height, spectral peak and mean periods and complex) and integral parameters (Irribaren and Ursell numbers) to analyse dependence bottom deformations on it. Self-organising of bottom relief and waves were studied on a scale of several storms. Results of investigations show that increase of significant wave height and spectral peak period of wave entering in coastal zone as well as Ursell number lead to erosion, which was localised in first 100 m near on barred profile and covered whole observed profile in case without bar. Features of sediment transport by forming a mobile temporal underwater bar were examined for cases of flat sloping and barred underwater beach profiles. On timescale of one storm type of wave breaking affect sediment transport: plunging wave breaking is responsible for formation and evolution of underwater sand bar as well as decreasing of sediment amount in upper part of beach profile and shoreline regression, while spilling do not lead to significant bottom deformations. The work was supported by Russian Foundation of Basic Research (grants 16-55-76002 (ERA-a), 16-35-00542 (mol_a), 15-05-08239, 15-05-04669).

Owen Martin Phillips (1930-2010)

NASA Astrophysics Data System (ADS)

Olson, Peter

2011-02-01

Owen Martin Phillips, a pioneer in geophysical fluid dynamics, died at home on 13 October 2010 in Chestertown, Md., at the age of 79. To his many friends and colleagues, Phillips was an inspirational and gracious person who combined a deep intellect, a lively spirit, and a generous heart that matched his passionate interest in the geophysical sciences. Phillips was born on 30 December 1930 in Parramatta, N. S. W., Australia. In 1948 he enrolled in the University of Sydney, where he earned a B.S. in applied mathematics in 1952. That same year, he joined the Cavendish Laboratory at Cambridge University as a research student, where he began to apply to the ocean concepts in turbulent flow recently developed by Andrei Kolmogorov, G. I. Taylor, and George Batchelor. While attending the 1956 celebration of Taylor's seventieth birthday, Phillips heard Fritz Ursell declare that “the process by which ocean waves are generated by the wind cannot be regarded as known.” In 1957 the Journal of Fluid Mechanics contained two remarkable papers offering contrasting theories for ocean wave generation. One paper, by the applied mathematician John Miles (J. Fluid Mech., 2(5), 417-445, 1957), proposed that energy transfer from the air to the sea occurs at a critical layer in the atmosphere boundary layer. The other paper, by Phillips, then 26 years old (J. Fluid Mech., 3(2), 185-204, 1957), proposed that turbulent pressure fluctuations in the wind resonate with propagating ocean waves, forcing them to grow. Together these became known as the Phillips-Miles process, and it was the opening salvo in Phillips's 50-year career of innovative contributions to geophysics through fluid mechanics.

Experimental Study of Large-Amplitude Faraday Waves in Rectangular Cylinders

NASA Technical Reports Server (NTRS)

Iek, Chanthy; Alexander, Iwan J.; Tin, Padetha; Adamovsky, Gregory

2005-01-01

Experiment on single-mode Faraday waves having two, thee, and four wavelengths across a rectangular cylinder of high aspect ratio is the subject of discussion. Previous experiments recently done by Henderson & Miles (1989) and by Lei Jiang et. a1 (1996) focused on Faraday waves with one and two wavelengths across rectangular cylinders. In this experimental study the waves steepness ranges from small at threshold levels to a large amplitude which according to Penny & Price theory (1952) approaches the maximum sustainable amplitude for a standing wave. The waves characteristics for small amplitudes are evaluated against an existing well known linear theory by Benjamin & Ursell (l954) and against a weakly nonlinear theory by J. Miles (1984) which includes the effect of viscous damping. The evaluation includes the wave neutral stability and damping rate. In addition, a wave amplitude differential equation of a linear theory including viscous effect by Cerda & Tirapegui (1998) is solved numerically to yield prediction of temporal profiles of both wave damping and wave formation at the threshold. An interesting finding from this exercise is that the fluid kinematic viscosity needs to increase ten times in order to obtain good agreement between the theoretical prediction and the experimental data for both wave damping and wave starting. For large amplitude waves, the experimental data are evaluated against the theory of Penny & Price which predicts wave characteristics of any amplitude up to the point at which the wave reaches its maximum amplitude attainable for a standing wave. The theory yields two criteria to show the maximum wave steepness, the vertical acceleration at the wave crest of half the earth gravity field acceleration and the including angle at the crest of 90 degrees. Comparison with experimental data shows close agreement for the wave crest acceleration but a large discrepancy for the including angle. Additional information is included in the original extended abstract.

Training Guidelines for Endovascular Ischemic Stroke Intervention: An International multi-society consensus document

PubMed Central

2016-01-01

Contributors American Academy of Neurological Surgeons/ Congress of Neurological Surgeons (AANS/CNS): S.D. Lavine, K Cockroft, B Hoh, N Bambakidis, AA Khalessi, H Woo, H Riina. A. Siddiqui American Society of Neuroradiology (ASNR): J. A. Hirsch Asian Australasian Federation of Interventional and Therapeutic Neuroradiology (AAFITN): W. Chong Australian and New Zealand Society of Neuroradiology - Conjoint Committee for Recognition of Training in Interventional Neuroradiology (CCINR) representing the RANZCR (ANZSNR), ANZAN and NSA: H. Rice, J Wenderoth, P Mitchell, A Coulthard, TJ Signh, C Phatorous, M Khangure Canadian Interventional Neuro Group (CING): P. Klurfan, K. Terbrugge, D Iancu, T. Gunnarsson European Society of Neuroradiology (ESNR); O. Jansen, M. Muto European Society of Minimally Invasive Neurologic Therapy (ESMINT): I. Szikora L. Pierot P. Brouwer J. Gralla, S. Renowden, T. Andersson, J. Fiehler, F. Turjman, P. White, AC Januel, L Spelle, Z Kulcsar, R Chapot, L Spelle, A Biondi, S Dima, C Taschner, M Szajner, A Krajina Japanese Society for Neuroendovascular therapy (JSNET): N.Sakai, Y. Matsumaru, S. Yoshimura Sociedad Ibero Latino Americana de Neuroradiologica (SILAN): O.Diaz, P.Lylyk Society of NeuroInterventional Surgery (SNIS): M.V. Jayaraman, A. Patsalides, C. D. Gandhi, S.K.Lee, T. Abruzzo, B. Albani, S. A. Ansari, A.S. Arthur, B.W. Baxter, K.R.Bulsara, M. Chen, J.E.Delgado-Almandoz, J.F.Fraser, D.V. Heck, S.W. Hetts, M.S.Hussain, R.P. Klucznik, T.M. Leslie-Mawzi, W.J.Mack, R.A.McTaggart, P.M.Meyers, J. Mocco, C.J.Prestigiacomo, G.L.Pride, P.A.Rasmussen, R.M.Starke, P.J.Sunenshine, R.W.Tarr, D.F.Frei Society of Vascular and Interventional Neurology (SVIN): M.Ribo, R.G.Nogeuira, O.O. Zaidat, T. Jovin, I. Linfante, D. Yavagal, D. Liebeskind, R. Novakovic World Federation of Interventional and Therapeutic Neuroradiology (WFITN): S. Pongpech, G Rodesch, M Soderman, K ter Brugge, A. Taylor, T Krings, D Orbach, A. Biondi, L Picard, D C Suh, M. Tanaka, HQ Zhang PMID:26957547

EDITORIAL: Deep brain stimulation, deontology and duty: the moral obligation of non-abandonment at the neural interface Deep brain stimulation, deontology and duty: the moral obligation of non-abandonment at the neural interface

NASA Astrophysics Data System (ADS)

Fins, Joseph J.; MD; FACP

2009-10-01

At the height of the psychosurgery debate the editors of The Lancet referenced the popular hesitancy to intervene surgically with the workings of the brain. They wrote that to do so `carries a peculiar penumbra of sacrilege' [1, 2]. Penumbra of sacrilege is a memorable, even strange phrase. It is one worth unpacking as we embark on an era which will see ever more border crossings at the blood-brain barrier. By invoking popular beliefs about a penumbra of sacrilege, the editors were suggesting that psychosurgery represented a gray zone in the shadows, a desecration or violation of a sacred space, the seat of the soul, the self. And as such, they were reflecting a cultural hesitancy, a lay reluctance to pursue this work. Fortunately for those with intractable neuropsychiatric disorders, neuromodulation has evolved beyond the primitive—and barbaric—sweep of the lobotomy, and with this advance, categorical resistance to this work has dissipated. And that is all to the good. But as the field progresses, and we implant more and more devices for therapeutic and investigational purposes, we must not let the placement of electrodes become too easy. It is a decision that should be made with full awareness of its implications for patients and families. Recently, I spoke to a friend who appeared to have early essential tremor. (Some non-essential aspects of this story have been changed to protect confidentiality.) He asked me, `Do you know anything about deep brain stimulation?' I indicated that I did. `Really?', he asked, seemingly unaware of my scholarly interest in the topic [3, 4, 5, 6] and involvement as a co-investigator in the use of deep brain stimulation in the minimally conscious state [7, 8, 9]. Satisfied that I might be a credible source for some free advice, he told me that his neurologist had sent him to a neurosurgeon to see about a stimulator. I asked him how disabling his condition was. As he competently drank a cup of soda, he told me it was a bit of a nuisance but nothing worse. As I recall the conversation, he was not receiving much more than a low-dose beta-blocker by way of medical management. Although I am an internist, and neither a neurologist nor neurosurgeon, it struck me as a bit premature to shuttle my friend off for an implant. It just should not be so easy. I asked myself: where had that penumbra of sacrilege gone? At some level, has this gotten too easy, too routine? Although this is but an anecdote, it is a disturbing one. My friend's referral was outside coverage norms established by the Centers for Medicare & Medicaid Services (CMS). Their 2003 national coverage determination for thalamic ventralis intemedius nucleus (VIM) deep brain stimulation (DBS) in essential tremor requires `marked disabling tremor of at least level 3 or 4 on the Fahn-Tolosa-Marin tremor rating scale (or equivalent scale) in the extremity intended for treatment, causing significant limitation in daily activities despite optimal medical therapy' [10, 11]. As best as I could tell, my friend met neither criteria for symptom severity nor adequate medical treatment. Even more striking was the casualness with which he told me about his neurologist's referral. One would think that he was being sent for the simplest of procedures, without any risks or long-term sequelae, notwithstanding specific complications associated with thalamic DBS for essential tremor [12]. It is a tribute to the nascent field of neuromodulation that, in the twenty years since Professor Alim Benabid's pioneering work heralded these new treatment modalities [13], stimulator placement has been analogized to the insertion of a heart pacemaker. But is the insertion of a cerebral pacemaker as routine as its cardiac counterpart? At this juncture I would venture to say it is not. While the acute surgical risks are slim, the longitudinal challenge for competent on-going care is high. Simply put, the community-based infrastructure to follow and support the growing number of patients with deep brain stimulators does not exist. Most patients go to highly specialized centers that have interdisciplinary teams able to assess, implant and support patients. But after surgery they return to their communities only to find a paucity of qualified neurologists and neurosurgeons able to provide on-going care. Even for rather routine matters like battery replacement or the adjustment of stimulation parameters, they need to return to the centers that performed the surgery. Follow-up there is all the more necessary for hardware failures, which still occur at non-trivial rates [14, 15]. This dependence on the mother ship is not the same for cardiac pacemakers. Any community hospital with a cardiology service can handle most complications and provide routine maintenance. Until a comparable neuromodulation infrastructure is in place, we need to be more prudent in determining who gets a stimulator. The prospects are even worse for those who are enrolled in clinical trials for new indications or have an innovative investigational device. What is their fate? What happens to these patients when the trial ends? Who provides on-going care? Who pays for battery replacement? Who removes a broken device? Who adjusts stimulation parameters ... in perpetuity? Because there is still virtually no group to take on these tasks, it is critically important that the neuromodulation community collectively affirm our on-going ethical obligation to these subjects once they leave trials and become patients. Our professional norms should reflect adherence to the ethical principle of non-abandonment. This duty is grounded in a deontological respect for persons. In the context of a neuromodulation trial, this means that once a subject is enrolled in a trial or under our care, we have a longitudinal fiduciary obligation to provide them with support. After a subject is implanted, the investigative team—and its sponsors—incur a clinical responsibility to provide on-going care and a fiscal responsibility for any associated costs. It is a breach of professional ethics to do otherwise. Such enduring covenants must be articulated in clinical protocols and be determinative in regulatory decisions by local Institutional Review Boards (IRBs) to reject or approve investigative protocols. The articulation of such `after-care' provisions should also be expected in any new IDE application to the Food and Drug Administration. To sustain clinical progress and investigative momentum, the neuromodulation community must embrace its ethical responsibility for comprehensive and on-going follow-up care. We need to populate a clinical infrastructure that can support patients and research subjects in their communities, especially as their conditions deteriorate and travel becomes more difficult. We need to disseminate our sequestered expertise more widely to primary care specialties. This ethical mandate transcends the clinical assessors, operators, and sponsors of clinical trials. It also applies to engineers who are well-positioned to help lessen the burden for patients and subjects. On the engineering side of this equation, innovation is the key. The development of better batteries with longer shelf lives or power management systems that optimize utilization of available capacitance will be a tremendous boon in streamlining follow-up care. So too will be the development of simplified device control systems to manipulate basic functions that would be operable by generalist physicians. Imagine a universal wand that could deactivate a device, and perform some rudimentary functions, that every Emergency Department could stock. Making such a basic parallel low-tech system universal amongst many device manufacturers would provide additional access to care in the community and a degree of safety in an emergency. Engineers might also work towards the development of mechanisms to give patients and subjects greater control over their devices, which are after all extrinsic intrusions on their bodies and their selves. Previously, I suggested that stimulation parameters for the treatment of neuropsychiatric disorders might be manipulated by patients one day. I envisioned a degree of patient discretion, within a pre-set safe range determined by physicians, much like patient-controlled analgesia (PCA) pumps give patients control over the dosing of opioid analgesia [3]. I am glad that such an advance is evolving as a means to preserve batteries in the treatment of motor disorders [16]. I would encourage the neural engineers to embrace the ethical mandate to develop additional platforms that might enhance patient self-determination and foster a greater degree of functional independence. While the neuromodulation community has every reason to celebrate its accomplishments, it would be better served by appreciating that the insertion of a device into the human brain comes with, if not the penumbra of sacrilege, a moral obligation to step out of the shadows and remain clearly available to patients and families over the long haul. Although neuromodulation has liberated many patients from the shackles of disease, we need to appreciate that the hardware that has made this possible can remain tethering. The challenge for the next generation of innovators is to minimize these burdens at this neural interface. By reducing barriers to care that exist in an unprepared health care system and developing more user-friendly technology, the neuromodulation community can expand its reach and broaden the relief provided by these neuro-palliative interventions [17]. Acknowledgements and Disclosures Dr Fins is the recipient of an Investigator Award in Health Policy Research (Minds Apart: Severe Brain Injury and Health Policy) from The Robert Wood Johnson Foundation. He also gratefully acknowledges grant support from the Buster Foundation (Neuroethics and Disorders of Consciousness). He is an unfunded co-investigator of a study of deep brain stimulation in the minimally conscious state, funded by Intelect Medical Inc. References [1] 1972 Editorial: Psychosurgery Lancet 7767 69-70 [2] Fins J J 2002 The ethical limits of neuroscience The Lancet Neurology 1 213 [3] Fins J J 2003 From psychosurgery to neuromodulation and palliation: history's lessons for the ethical conduct and regulation of neuropsychiatric research Neurosurgery Clinics of North America 14 303-19 [4] Fins J J 2004 Deep brain stimulation Encyclopedia of Bioethics, Vol 2 3rd edn, ed S G Post (New York: MacMillan Reference) pp 629-34 [5] Fins J J 2004 Neuromodulation, free will and determinism: lessons from the psychosurgery debate Clinical Neuroscience Research 4 113-18 [6] Fins J J 2009 Deep brain stimulation: ethical issues in clinical practice and neurosurgical research Neuromodulation eds E Krames, P H Peckham and A Rezai (London: Elsevier) pp 81-91 [7] Schiff N D, Giacino J T, Kalmar K, Victor J D, Baker K, Gerber M, Fritz B, Eisenberg B, O'Connor J, Kobylarz E J, Farris S, Machado A, McCagg C, Plum F, Fins J J, Rezai A R 2007 Behavioral improvements with thalamic stimulation after severe traumatic brain injury Nature 448 600-3 [8] Schiff N D and Fins J J 2007 Deep brain stimulation and cognition: moving from animal to patient Current Opinion in Neurology 20 638-42 [9] Schiff N D, Giacino J T and Fins J J 2009 Deep brain stimulation, neuroethics and the minimally conscious state: moving beyond proof of principle Arch. Neurology 66 697-702 [10] CMS 160.24 NCD for deep brain stimulation for essential tremor and Parkinson's disease, 1~April~2003 [11] CMS Manual System 100-04 Medicare claims processing, transmittal 128, 26 March 2004 http://www.cms.hhs.gov/Transmittals/Downloads/R128CP.pdf [12] Schwalb J M, Riina H A, Skolnick B, Jaggi J L, Simuni T and Baltuch G H 2001 Revision of deep brain stimulator for tremor: technical note J. Neurosurg. 94 1010-12 [13] Speelman J D and Bosch D A 1998 Resurgence of functional neurosurgery for Parkinson's disease: a historical perspective Movement Disorders 13 582-8 [14] Kondziolka D, Whiting D, Germanwala A and Oh M 2002 Hardware-related complications after placemen of thalamic deep brain stimulator systems Stereotact. Funct. Neurosurg. 79 228-33 [15] Okun M S, Tagliati M, Pourfar M, Fernandez H H, Rodriguez R L, Alterman R L and Foote K~D 2005 Management of referred deep brain stimulation failures: a retrospective analysis from movement disorders centers Arch. Neurology 62 1250-5 [16] Kronenbuerger M, Fromm C, Block F, Coenen V A, Rohde I, Rohde V and Noth J 2006 On-demand deep brain stimulation for essential tremor: a report on four cases Movement Disorders 21 401-5 [17] Fins J J 2008 Neuroethics and disorders of consciousness: a pragmatic approach to neuro-palliative care The Neurology of Consciousness, Cognitive Neuroscience and Neuropathology eds S Laureys and G Tononi (New York: Academic-Elsevier) pp 234-44