WorldWideScience

Sample records for benign stab detonators

  1. Environmentally Benign Stab Detonators

    Energy Technology Data Exchange (ETDEWEB)

    Gash, A

    2005-12-21

    Many energetic systems can be activated via mechanical means. Percussion primers in small caliber ammunition and stab detonators used in medium caliber ammunition are just two examples. Current medium caliber (20-60mm) munitions are detonated through the use of impact sensitive stab detonators. Stab detonators are very sensitive and must be small, as to meet weight and size limitations. A mix of energetic powders, sensitive to mechanical stimulus, is typically used to ignite such devices. Stab detonators are mechanically activated by forcing a firing pin through the closure disc of the device and into the stab initiating mix. Rapid heating caused by mechanically driven compression and friction of the mixture results in its ignition. The rapid decomposition of these materials generates a pressure/temperature pulse that is sufficient to initiate a transfer charge, which has enough output energy to detonate the main charge. This general type of ignition mix is used in a large variety of primers, igniters, and detonators.[1] Common primer mixes, such as NOL-130, are made up of lead styphnate (basic) 40%, lead azide (dextrinated) 20%, barium nitrate 20%, antimony sulfide 15%, and tetrazene 5%.[1] These materials pose acute and chronic toxicity hazards during mixing of the composition and later in the item life cycle after the item has been field functioned. There is an established need to replace these mixes on toxicity, health, and environmental hazard grounds. This effort attempts to demonstrate that environmentally acceptable energetic solgel coated flash metal multilayer nanocomposites can be used to replace current impact initiated devices (IIDs), which have hazardous and toxic components. Successful completion of this project will result in IIDs that include innocuous compounds, have sufficient output energy for initiation, meet current military specifications, are small, cost competitive, and perform as well as or better than current devices. We expect flash

  2. Environmentally Benign Stab Detonators

    Energy Technology Data Exchange (ETDEWEB)

    Gash, A E

    2006-07-07

    The coupling of energetic metallic multilayers (a.k.a. flash metal) with energetic sol-gel synthesis and processing is an entirely new approach to forming energetic devices for several DoD and DOE needs. They are also practical and commercially viable manufacturing techniques. Improved occupational safety and health, performance, reliability, reproducibility, and environmentally acceptable processing can be achieved using these methodologies and materials. The development and fielding of this technology will enhance mission readiness and reduce the costs, environmental risks and the necessity of resolving environmental concerns related to maintaining military readiness while simultaneously enhancing safety and health. Without sacrificing current performance, we will formulate new impact initiated device (IID) compositions to replace materials from the current composition that pose significant environmental, health, and safety problems associated with functions such as synthesis, material receipt, storage, handling, processing into the composition, reaction products from testing, and safe disposal. To do this, we will advance the use of nanocomposite preparation via the use of multilayer flash metal and sol-gel technologies and apply it to new small IIDs. This work will also serve to demonstrate that these technologies and resultant materials are relevant and practical to a variety of energetic needs of DoD and DOE. The goal will be to produce an IID whose composition is acceptable by OSHA, EPA, the Clean Air Act, Clean Water Act, Resource Recovery Act, etc. standards, without sacrificing current performance. The development of environmentally benign stab detonators and igniters will result in the removal of hazardous and toxic components associated with their manufacturing, handling, and use. This will lead to improved worker safety during manufacturing as well as reduced exposure of Service personnel during their storage and or use in operations. The

  3. Stab Sensitivity of Energetic Nanolaminates

    Energy Technology Data Exchange (ETDEWEB)

    Gash, A; Barbee, T; Cervantes, O

    2006-05-22

    This work details the stab ignition, small-scale safety, and energy release characteristics of bimetallic Al/Ni(V) and Al/Monel energetic nanolaminate freestanding thin films. The influence of the engineered nanostructural features of the energetic multilayers is correlated with both stab initiation and small-scale energetic materials testing results. Structural parameters of the energetic thin films found to be important include the bi-layer period, total thickness of the film, and presence or absence of aluminum coating layers. In general the most sensitive nanolaminates were those that were relatively thick, possessed fine bi-layer periods, and were not coated. Energetic nanolaminates were tested for their stab sensitivity as freestanding continuous parts and as coarse powders. The stab sensitivity of mock M55 detonators loaded with energetic nanolaminate was found to depend strongly upon both the particle size of the material and the configuration of nanolaminate material, in the detonator cup. In these instances stab ignition was observed with input energies as low as 5 mJ for a coarse powder with an average particle dimension of 400 {micro}m. Selected experiments indicate that the reacting nanolaminate can be used to ignite other energetic materials such as sol-gel nanostructured thermite, and conventional thermite that was either coated onto the multilayer substrate or pressed on it. These results demonstrate that energetic nanolaminates can be tuned to have precise and controlled ignition thresholds and can initiate other energetic materials and therefore are viable candidates as lead-free impact initiated igniters or detonators.

  4. Detonation

    International Nuclear Information System (INIS)

    The use of high explosives to propel or compress materials leads to a particular area of the fluid mechanics characterized by non-stationary flows with shock and detonation waves. This course provides the basic concepts in physics and chemistry for engineers involved in design and development of pyrotechnic devices or military charges. (author)

  5. The imaging of stab injuries

    Energy Technology Data Exchange (ETDEWEB)

    Vries, Coert S. de; Africa, Mogoeemang; Gebremariam, Fekade A.; Rensburg, J. Janse van; Otto, Susan F.; Potgieter, Henrik F. (Dept. of Diagnostic Radiology, Faculty of Health Sciences, Univ. of the Free State and Academic Health Complex, Free State Province Dept. of Health, Bloemfontein (South Africa)), e-mail: devriesc.md@ufs.ac.za

    2010-01-15

    In the trauma unit of the Bloemfontein Academic Complex, the total number of stab wounds seen represents approximately 70.5% of penetrating injuries, which is 6.4% of 5004 trauma cases seen in a period of 1 year. The other cases are gunshot wounds and pedestrian or motor vehicle accidents. Specific guidelines and protocols are followed for penetrating trauma management. All imaging modalities are utilized, with chest radiography the mainstay of thoracic imaging in patients having sustained sharp penetrating chest injuries. Computed tomography (CT) is being used more frequently as the primary imaging modality in the evaluation of hemodynamically stable patients with penetrating injuries. The improved speed of data acquisition and superior image reconstruction of multidetector CT (MDCT) has further driven this change in imaging approach. Although digital subtraction angiography (DSA) has been the reference standard for the diagnosis of traumatic vascular injuries, it is giving way to faster, less invasive, and less personnel-intensive imaging techniques, e.g., MDCT angiography. Given the fact that we work in an academic environment and that we have a dedicated interventional unit, arteriography is still frequently performed and still has its place as the 'gold standard' in the diagnosis of vascular injuries. Penetrating chest injuries suspected of traversing the mediastinum or extending near the posterior mediastinal structures dictate esophageal and tracheal evaluation. Although radiology has a role to play, direct visualization (esophagoscopy, bronchoscopy) remains the most reliable method of excluding injuries to these structures. Transthoracic ultrasound (echocardiography) has become indispensable in helping to evaluate injuries to the heart and the ascending and descending aortas. More recent work has demonstrated that ultrasonography can also be used to detect hemothoraces and pneumothoraces with accuracy

  6. Sunflower detonation

    OpenAIRE

    Kasimov, A.; Korneev, S.

    2012-01-01

    In this fluid dynamic video we present simulations of converging two-dimensional detonation in a radially expanding supersonic flow of ideal reactive gas. The detonation is found to be unstable and leads to formation of characteristic cellular patterns. Without any obstacles in the flow, the detonation keeps expanding radially. To retain the wave within a bounded region, we place a number of rigid obstacles in the flow so that the detonation shock stands some distance toward the center from t...

  7. 17th STAB/DGLR Symposium

    CERN Document Server

    Heller, Gerd; Kreplin, Hans-Peter; Nitsche, Wolfgang; Peltzer, Inken

    2013-01-01

    This volume contains the contributions to the 17th Symposium of STAB (German Aerospace Aerodynamics Association). STAB includes German scientists and engineers from universities, research establishments and industry doing research and project work in numerical and experimental fluid mechanics and aerodynamics, mainly for aerospace but also for other applications. Many of the contributions collected in this book present results from national and European Community sponsored projects. This volume gives a broad overview of the ongoing work in this field in Germany and spans a wide range of topics: airplane aerodynamics, multidisciplinary optimization and new configurations, hypersonic flows and aerothermodynamics, flow control (drag reduction and laminar flow control), rotorcraft aerodynamics, aeroelasticity and structural dynamics, numerical simulation, experimental simulation and test techniques, aeroacoustics as well as the new fields of biomedical flows, convective flows, aerodynamics and acoustics of high-s...

  8. 18th STAB/DGLR Symposium

    CERN Document Server

    Heller, Gerd; Krämer, Ewald; Kreplin, Hans-Peter; Nitsche, Wolfgang; Rist, Ulrich

    2014-01-01

    This book presents contributions to the 18th biannual symposium of the German Aerospace Aerodynamics Association (STAB). The individual chapters reflect ongoing research conducted by the STAB members in the field of numerical and experimental fluid mechanics and aerodynamics, mainly for (but not limited to) aerospace applications, and cover both nationally and EC-funded projects. By addressing a number of essential research subjects, together with their related physical and mathematics fundamentals, the book provides readers with a comprehensive overview of the current research work in the field, as well as its main challenges and new directions. Current work on e.g. high aspect-ratio and low aspect-ratio wings, bluff bodies, laminar flow control and transition, active flow control, hypersonic flows, aeroelasticity, aeroacoustics and biofluid mechanics is exhaustively discussed here.  .

  9. Evaluation of penetrating cardiac stab wounds

    OpenAIRE

    Bamous, Mehdi; Abdessamad, Abdou; Tadili, Jawad; Kettani, Ali; Faroudy, Mamoun

    2016-01-01

    Background The purpose of this study was to identify factors associated with unfavourable outcome following stab wounds to the heart in order to improve selection of patients who may benefit from resuscitative effort. Methods From February to March, variables were collected from medical records of patients sustaining cardiac trauma. The inclusion criterion was the presence of a penetrating cardiac injury confirmed intraoperatively. Results Ninety-eight patients were admitted with penetrating ...

  10. 11th AG STAB/DGLR Symposium

    CERN Document Server

    Heinemann, Hans-Joachim; Hilbig, Reinhard

    1999-01-01

    This volume contains the papers of the 11th Symposium of the AG STAB (German Aerospace Aerodynamics Association). In this association those scientists and engineers from universities, research-establishments and industry are involved, who are doing research and project work in numerical and experimental fluid mechanics and aerodynamics for aerospace and other applications. Many of the contributions are giving results from the "Luftfahrtforschungsprogramm der Bundesregierung (German Aeronautical Research Programme). Some of the papers report on work sponsored by the Deutsche Forschungsgemeinschaft, DFG, which also was presented at the symposium. The volume gives a broad overview over the ongoing work in this field in Germany.

  11. Sunflower detonation

    CERN Document Server

    Kasimov, A

    2012-01-01

    At this fluid dynamic video we present the instability formation of converging two-dimensional detonation in a radially expanding flow of ideal gas. This unstable pattern expands in space and goes out of the calculation domain. To keep this pattern inside bounded region, we surrounded it by obstacles. The pattern and shock waves reflected from the obstacles forms the structure which we call "sunflower detonation".

  12. 76 FR 69764 - Stab-Resistant Body Armor Standard Workshop

    Science.gov (United States)

    2011-11-09

    ... of Justice Programs Stab-Resistant Body Armor Standard Workshop AGENCY: National Institute of Justice... Standards and Technology (NIST) are jointly hosting a workshop focused on the NIJ Stab-resistant Body Armor.... This workshop is being held specifically to discuss with interested parties recent progress made...

  13. Characteristics and rehabilitation for patients with spinal cord stab injury

    OpenAIRE

    Wang, Fangyong; Zhang, Junwei; Tang, Hehu; LI, XIANG; Jiang, Shudong; Lv, Zhen; Liu, Shujia; Chen, Shizheng; Liu, Jiesheng; Hong, Yi

    2015-01-01

    [Purpose] The objective of the study was to compare the incidence, diagnosis, treatment, and prognosis of patients with spinal cord stab injury to those with the more common spinal cord contusion injury. [Subjects] Of patients hospitalized in China Rehabilitation Research Center from 1994 to 2014, 40 of those having a spinal cord stab injury and 50 with spinal cord contusion were selected. [Methods] The data of all patients were analyzed retrospectively. The cases were evaluated by collecting...

  14. Mechanics of Stabbing: Biaxial Measurement of Knife Stab Penetration of Skin Simulant

    CERN Document Server

    Gilchrist, Michael D; Curtis, Michael; Cassidy, Mary; Byrne, Greg; Destrade, Michel; 10.1016/j.forsciint.2007.10.010

    2008-01-01

    In medicolegal situations, the consequences of a stabbing incident are described in terms that are qualitative without being quantitative. Here, the mechanical variables involved in knife-tissue penetration events are used to determine the parameters needed to be controlled in a measurement device. They include knife geometry, in-plane mechanical stress state of skin, angle and speed of knife penetration, and underlying fascia. Four household knives with different geometries were used. Synthetic materials were used to simulate the response of skin, fat and cartilage: polyurethane, foam, and ballistic soap, respectively. The force and energy applied by the blade and the skin displacement were used to identify skin penetration. The skin tension is shown to have a direct effect on the force and energy for knife penetration and on the depth of displacement of the simulant prior to penetration: larger levels of in-plane tension in the skin are associated with lower penetration forces, energies and displacements. L...

  15. Standing detonation wave engine

    KAUST Repository

    Kasimov, Aslan

    2015-10-08

    A detonation engine can detonate a mixture of fuel and oxidizer within a cylindrical detonation region to produce work. The detonation engine can have a first and a second inlet having ends fluidly connected from tanks to the detonation engine. The first and second inlets can be aligned along a common axis. The inlets can be connected to nozzles and a separator can be positioned between the nozzles and along the common axis.

  16. GeoStab: program for beregning av skråninsstabilitet - Versjon 1.0

    OpenAIRE

    Bruun, Hermann

    2000-01-01

    Rapporten gir veiledning i bruk av stabilitetsprogrammet GeoStab. GeoStab er et windowsbasert program som kan benytte seg av grunnlagsdata fra NovaPoint modulene GeoPlot, Veg, TMOD og VIPS. Brukergrensesnittet til GeoStab er meget fleksibelt og kan tilpasses avhengig av hvilke grunnlagsdata som er tilgjengelig.

  17. Class characteristics of serrated knife stabs to cartilage.

    Science.gov (United States)

    Pounder, Derrick J; Cormack, Lesley; Broadbent, Elizabeth; Millar, John

    2011-06-01

    A total of 136 stab wounds were made in cartilage with 8 serrated knives and 72 stabs with 4 nonserrated knives. The walls of the stab track were documented by photography, cast with dental impression material, and the casts photographed. Staining the translucent cartilage surface with blue or green food dye improved photography. Serrated blades produced striations on cartilage in all stabbings. Patterns of blade serration beyond the broad categories of coarse and fine were recognizable. The overall pattern of striations was "irregularly regular." The distance between the blade-spine wound end and the first serration striation is a class characteristic of the knife which produced the defect, as are distances to the subsequent serration striations, which become ever close together and eventually merge near the blade-edge wound end. Serrated knives may be ground (scalloped) on either the left side or the right side of the blade and this class characteristic is identifiable from the walls of the wound track, on which the scalloped blade surface produces broad ridges and narrow striation valleys, with a reverse image on the opposing wound wall. A drop point serrated blade consistently produced an additional oblique mark angled from the blade-spine wound end, accurately reflecting the shape of the blade tip, and representing a chatter mark. PMID:20407362

  18. Stab Wound of the Heart with Unusual Sequelae

    OpenAIRE

    Praeger, Peter I.; Praeger, Jonathan; Ahmed M Abdel-Razek; Elmann, Elie M.

    2013-01-01

    A 31-year-old woman was admitted to the emergency department with a stab wound to the heart. She was initially stable but rapidly developed hypotension. While the operating room and staff were in preparation, she underwent pericardiocentesis. She was then rushed to the operating room by the general surgical trauma team, who performed a bilateral anterior thoracotomy to control the bleeding. In the recovery room, the patient was still hypotensive, so cardiothoracic surgery was consulted.

  19. Detonation Wave Profile

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-14

    The Zel’dovich-von Neumann-Doering (ZND) profile of a detonation wave is derived. Two basic assumptions are required: i. An equation of state (EOS) for a partly burned explosive; P(V, e, λ). ii. A burn rate for the reaction progress variable; d/dt λ = R(V, e, λ). For a steady planar detonation wave the reactive flow PDEs can be reduced to ODEs. The detonation wave profile can be determined from an ODE plus algebraic equations for points on the partly burned detonation loci with a specified wave speed. Furthermore, for the CJ detonation speed the end of the reaction zone is sonic. A solution to the reactive flow equations can be constructed with a rarefaction wave following the detonation wave profile. This corresponds to an underdriven detonation wave, and the rarefaction is know as a Taylor wave.

  20. Isothermal Gaseous Detonation Model

    Science.gov (United States)

    Prokhorov, E. S.

    2015-05-01

    We propose an isothermal gaseous detonation model taking into account the initial pressure of the explosive mixture that permits describing in a simplified form both the self-sustaining and the supercompressed and undercompressed detonation regimes. The exactness of this model has been estimated on the basis of a comparative analysis with the results of equilibrium calculations of the gas-dynamic parameters at the front of detonation waves.

  1. Detonation command and control

    Science.gov (United States)

    Mace, Jonathan L.; Seitz, Gerald J.; Echave, John A.; Le Bas, Pierre-Yves

    2015-11-10

    The detonation of one or more explosive charges and propellant charges by a detonator in response to a fire control signal from a command and control system comprised of a command center and instrumentation center with a communications link therebetween. The fire control signal is selectively provided to the detonator from the instrumentation center if plural detonation control switches at the command center are in a fire authorization status, and instruments, and one or more interlocks, if included, are in a ready for firing status. The instrumentation and command centers are desirably mobile, such as being respective vehicles.

  2. Detonation command and control

    Energy Technology Data Exchange (ETDEWEB)

    Mace, Jonathan L.; Seitz, Gerald J.; Echave, John A.; Le Bas, Pierre-Yves

    2016-05-31

    The detonation of one or more explosive charges and propellant charges by a detonator in response to a fire control signal from a command and control system comprised of a command center and instrumentation center with a communications link there between. The fire control signal is selectively provided to the detonator from the instrumentation center if plural detonation control switches at the command center are in a fire authorization status, and instruments, and one or more interlocks, if included, are in a ready for firing status. The instrumentation and command centers are desirably mobile, such as being respective vehicles.

  3. Hydrazine vapor detonations

    Science.gov (United States)

    Pedley, M. D.; Bishop, C. V.; Benz, F. J.; Bennett, C. A.; Mcclenagan, R. D.

    1988-01-01

    The detonation velocity and cell widths for hydrazine decomposition were measured over a wide range of temperatures and pressures. The detonation velocity in pure hydrazine was within 5 percent of the calculated C-J velocity. The detonation cell width measurements were interpreted using the Zeldovich-Doering-von Neumann model with a detailed reaction mechanism for hydrazine decomposition. Excellent agreement with experimental data for pure hydrazine was obtained using the empirical relation that detonation cell width was equal to 29 times the kinetically calculated reaction zone length.

  4. Folding Detonation Waves

    Directory of Open Access Journals (Sweden)

    V. P. Singh

    1983-01-01

    Full Text Available Propagation of converging detonation waves in solid explosive is discussed. Whitham's method modified for solid explosives is used. Using folding coordinates, it is found that the strength of detonation waves increases as it moves towards the centre of implosion.

  5. Converging Spherical Detonation Waves.

    Directory of Open Access Journals (Sweden)

    Arisudan Rai

    1998-04-01

    Full Text Available The problem of converging spherical detonation waves propagating through a gas with varyingdensity is discussed. By neglecting the effect of variation of Q on the similarity exponent, both analytical and numerical solutions for motion of the detonation front have been obtained and arepresented in graphical form.

  6. Converging Spherical Detonation Waves.

    OpenAIRE

    Arisudan Rai

    1998-01-01

    The problem of converging spherical detonation waves propagating through a gas with varyingdensity is discussed. By neglecting the effect of variation of Q on the similarity exponent, both analytical and numerical solutions for motion of the detonation front have been obtained and arepresented in graphical form.

  7. Management of stab wounds to the anterior abdominal wall

    Directory of Open Access Journals (Sweden)

    João Baptista Rezende-Neto

    2014-01-01

    Full Text Available The meeting of the Publication "Evidence Based Telemedicine - Trauma and Emergency Surgery" (TBE-CiTE, through literature review, selected three recent articles on the treatment of victims stab wounds to the abdominal wall. The first study looked at the role of computed tomography (CT in the treatment of patients with stab wounds to the abdominal wall. The second examined the use of laparoscopy over serial physical examinations to evaluate patients in need of laparotomy. The third did a review of surgical exploration of the abdominal wound, use of diagnostic peritoneal lavage and CT for the early identification of significant lesions and the best time for intervention. There was consensus to laparotomy in the presence of hemodynamic instability or signs of peritonitis, or evisceration. The wound should be explored under local anesthesia and if there is no injury to the aponeurosis the patient can be discharged. In the presence of penetration into the abdominal cavity, serial abdominal examinations are safe without CT. Laparoscopy is well indicated when there is doubt about any intracavitary lesion, in centers experienced in this method.

  8. Propagation Mechanism of Cylindrical Cellular Detonation

    Science.gov (United States)

    Han, Wen-Hu; Wang, Cheng; Ning, Jian-Guo

    2012-10-01

    We investigate the evolution of cylindrical cellular detonation with different instabilities. The numerical results show that with decreasing initial temperature, detonation becomes more unstable and the cells of the cylindrical detonation tend to be irregular. For stable detonation, a divergence of cylindrical detonation cells is formed eventually due to detonation instability resulting from a curved detonation front. For mildly unstable detonation, local overdriven detonation occurs. The detonation cell diverges and its size decreases. For highly unstable detonation, locally driven detonation is more obvious and the front is highly wrinkled. As a result, the diverging cylindrical detonation cell becomes highly irregular.

  9. [Current management of stab wounds to the colon].

    Science.gov (United States)

    Peycru, T; Avaro, J P; Biance, N; Tardat, E; Balandraud, P

    2006-06-01

    Stab wounds to the colon are a frequent surgical emergency. Local wound exploration under local anaesthesia is not required systematically. We recommend surveillance based on clinical observation and laboratory testing to detect peritoneal signs. If progression of symptoms is suspected, diagnostic peritoneal lavage (DPL) should be performed. Immediate surgical exploration is indicated in two cases, i.e., generalized peritonitis and haemodynamic instability due to internal bleeding. The preferred repair technique is direct suture or resection followed by a handsewn or mechanical anastomosis. The morbidity, cost and social consequences of colostomy must be taken into account. It should be considered as a salvage procedure for patients in critical condition or extensive colonic injury. PMID:16924827

  10. An Optimal Dynamic Data Structure for Stabbing-Semigroup Queries

    DEFF Research Database (Denmark)

    Agarwal, Pankaj K.; Arge, Lars; Kaplan, Haim; Molad, Eyal; Tarjan, Robert E.; Yi, Ke

    2012-01-01

    is the first data structure that attains the optimal $O(\\log n)$ bound for all three operations. Furthermore, our structure can easily be adapted to external memory, where we obtain a linear-size structure that answers queries and supports updates in $O(\\log_B n)$ I/Os, where B is the disk block size......{R}$, the stabbing-semigroup query asks for computing $\\sum_{s \\in S(q)} \\omega(s)$. We propose a linear-size dynamic data structure, under the pointer-machine model, that answers queries in worst-case $O(\\log n)$ time and supports both insertions and deletions of intervals in amortized $O(\\log n)$ time. It...

  11. Benign positional vertigo

    Science.gov (United States)

    Vertigo - positional; Benign paroxysmal positional vertigo; BPPV: dizziness- positional ... Benign positional vertigo is also called benign paroxysmal positional vertigo (BPPV). It is caused by a problem in the inner ear. ...

  12. Detonation safety of blasting caps

    Institute of Scientific and Technical Information of China (English)

    谢兴华; 彭小圣

    2002-01-01

    By means of researching into sympathetic detonation of blasting detonators in air, the regular patterns are concluded from blasting detonators interaction with the shock loading. The aerial distribution of initiating ability of detonators looks like a butterfly. The initiating ability mainly consists of shock wave, explosive gases and fliers. But fundamental questions remain. When does shock wave take the leading role? When and how does the explosive gases or the fliers take function? For those questions, there is less quantitative research. Through the theoretic deduction of the overpressure, the energy calculation of fliers and the experiment of sympathetic detonation of detonators, we can learn the sympathetic detonation distances of several kinds of detonators and make an inquiry into the lateral initiating regulations of detonators. So, we can provide the base data for the research into no sympathetic detonation of herd blasting detonators and then control the detonation between them. Then we can make full use of detonators and reduce the frequency of accidents caused by detonators.

  13. The use of etoricoxib to treat an idiopathic stabbing headache: a case report

    Directory of Open Access Journals (Sweden)

    O'Connor Mortimer B

    2007-09-01

    Full Text Available Abstract According to the International Headache Society, idiopathic stabbing headache (ISH, an indomethacin-responsive headache syndrome, is a paroxysmal disorder of short duration manifested as head pain occurring as a single stab or a series of stabs involving the area supplied in the distribution of the first division of the trigeminal nerve. Stabs last for approximately a few seconds, occurring and recurring from once to multiple times per day in an irregular frequency, with no underlying attributable disorder. Previously indomethacin was the principle treatment option for ISH, despite therapeutic failure in up to 35% of cases, until reports showed gabapentin, melatonin and selective cyclo-oxygenase-2 (COX-2 inhibitors were also possibly effective. In this report we present the full case report of an 88 year old lady with a history of untreated ISH where etoricoxib, a selective COX-2 inhibitor, was used to effectively treat her ISH.

  14. Pushable springcoil embolization of pseudoaneurysms caused by gluteal stab injuries

    International Nuclear Information System (INIS)

    Purpose: To retrospectively review the outcomes of 21 patients with stab wounds to the gluteal region who underwent embolization for pseudoaneurysms causing active bleeding. Materials and methods: Between 1997 and 2007, 3 superior gluteal artery, 2 inferior gluteal artery and 16 deep femoral artery muscular branch pseudoaneurysms detected by digital subtraction angiography were selectively catheterized with diagnostic catheters with hydrophilic coating and embolized with pushable springcoils. 17 of the 21 pseudoaneurysms were located in a distal end of an artery where outflow vessels could not be depicted. The other 4 lesions were side wall injuries which required the placement of coils distal and proximal to the injury site. Results: Embolization was successful in controlling the bleeding in all of the patients. 16 patients required 1 or 2 coils, 4 patients required 3 coils and 1 patient required 5 coils. 2 patients had femoral puncture site hematomas which resolved spontaneously. 2 patients required surgical evacuation of large gluteal hematomas following the embolization because of symptoms second to mass effect. There were no procedure related major complications or mortality. Conclusions: Our experience demonstrates that pushable coil embolization is a relatively simple, effective and economic method for the embolization of pseudoaneurysms caused by penetrating gluteal injuries. Experimenting with other embolization materials does not seem to be justified.

  15. Imploding Detonation Waves

    Directory of Open Access Journals (Sweden)

    B. G. Verma

    1981-01-01

    Full Text Available The problem of imploding detonation waves propagating through a gas with initial density, is studied. It is shown that the consideration of varying initial density affects the problem considerably incomparison to a uniform gas at rest. An analytical expression for the pressure distribution in the neighbourhood of the centre of symmetry has been found.

  16. Imploding Detonation Waves

    OpenAIRE

    B. G. Verma; Singh, J. B.

    1981-01-01

    The problem of imploding detonation waves propagating through a gas with initial density, is studied. It is shown that the consideration of varying initial density affects the problem considerably incomparison to a uniform gas at rest. An analytical expression for the pressure distribution in the neighbourhood of the centre of symmetry has been found.

  17. STAB INJURY: RETROSPECTIVE AND PROSPECTIVE STUDY IN TERTIARY CENTRE S IN CENTRAL INDIA

    Directory of Open Access Journals (Sweden)

    Raikwar

    2015-07-01

    Full Text Available AIMS AND OBJECTIVES: The aim of this study was to , 1. E valuate the incidence of stab injuries admitting in our institute, t o know various parameter and its association with injuries such as age group, sex ratio, clinical presentation . 2. V arious surgical interventi on and conservative treatment according the nature of stab injuries and through examination. 3. M orbidity and mortality of these patients , settings and design . The study was conducted in a retrospective and prospec tive manner and included cases b etween January 2009 and September 2013. METHODS AND MATERIAL S: 424 patients admitted with stab injuries in ICU and ward . Various surgical interventions were done according to standard indication such as laparotomies , thoracotomies, vascular repair etc. , and resul ts reported. RESULTS: Out of 424 patients t here were over all 413 mal es (97.4% and 11 female s (2.6% highest number of cases (226 in the third decade(21 - 30 i.e. 53.3% maximum number of cases are from 11 - 40 yrs. Majority of the stab wounds were homicidal in nature comprising 386 cases i.e. 91 % followed by are accidental. Chaku ( knife were the most common weapon . The Chaku was used in 351 cases i.e. 82.8% maximun numbers of patients 309 were presented with localised tende r ness at site of stab injury i.e 72.87%. In the perspective of management 244 abdominal stab that there were total 189(44.6% exploratory laparotomy . In 189 laparotomies peritoneal breech in 114 patients on local examination / exploration was the major indic ation there were 114 i.e ., 60.3% CONCLUSION: Stab injuri es are becoming common now a days because people often try to settle interpersonal relationship and political problems by mean of stabbing, although its incidence more in our country as compare d to European studies because of overpopulation unemployment and poverty. Incidence of stab injury can be reduced by improving the social morale of people especially the younger generation by

  18. Benign Liver Tumors

    Science.gov (United States)

    ... Handouts Education Resources Support Services Helpful Links For Liver Health Information Call 1-800-GO-LIVER (1- ... Liver > Liver Disease Information > Benign Liver Tumors Benign Liver Tumors Explore this section to learn more about ...

  19. Benign Multicystic Peritoneal Mesothelioma

    Science.gov (United States)

    ... Center (GARD) Print friendly version Benign multicystic peritoneal mesothelioma Table of Contents Overview Treatment Prognosis Living With ... Names for this Disease BMPM Benign cystic peritoneal mesothelioma Multilocular peritoneal inclusion cysts Multilocular peritoneal cysts About ...

  20. Mesothelioma - benign-fibrous

    Science.gov (United States)

    Mesothelioma - benign; Mesothelioma - fibrous; Pleural fibroma; Solitary fibrous tumor of the pleura ... other reasons. Other tests that may show benign mesothelioma include: CT scan of the chest Open lung ...

  1. Ultrasonic flaw detecting device for welded portion of stab and flaw detecting method therefor

    International Nuclear Information System (INIS)

    In the present invention, flaws are detected efficiently only for the welded portion of a stab disposed to a lower end plate of a pressure vessel used in a nuclear power plant. Namely, the device of the present invention comprises (1) an ultrasonic probe disposed to a shaft of the stab of control rod drives (CRD), (2) a shaft for supporting the ultrasonic probe, (3) a driving mechanism for circumferentially rotating and further axially moving the shaft, and (4) a controlling device for controlling the equipments described above and processing data. The position of the supersonic probe is moved vertically in the axial direction while rotating the shaft and rotating the supersonic probe in the circumferential direction by the driving mechanism driven upon receiving signals from the controlling device. Flaws can be detected only for the welded portion of the CRD stab using the ultrasonic probe by repeating the operation. In addition, efficiency for the flaw detecting operation is improved. (I.S.)

  2. Toroidal Imploding Detonation Wave Initiator for Pulse Detonation Engines

    OpenAIRE

    Jackson, S. I.; Shepherd, J. E.

    2007-01-01

    Imploding toroidal detonation waves were used to initiate detonations in propane–air and ethylene–air mixtures inside of a tube. The imploding wave was generated by an initiator consisting of an array of channels filled with acetylene–oxygen gas and ignited with a single spark. The initiator was designed as a low-drag initiator tube for use with pulse detonation engines. To detonate hydrocarbon–air mixtures, the initiator was overfilled so that some acetylene oxygen spilled into the tube. The...

  3. ABOUT THE DETONATION ENGINE

    OpenAIRE

    Bulat Pavel Viktorovich

    2014-01-01

    The research objects of this study are new principles of gas turbine and rocket engines working process organization, based on the oscillatory motion of shock and detonation waves. Purpose is to identify the state of level technology, describe the subject area, state the direction of research and formulate the main problems hindering the implementation of wave technology into mass production. The results presented in the study can be recommended for developers of aircraft engines, power and t...

  4. ABOUT THE DETONATION ENGINE

    Directory of Open Access Journals (Sweden)

    Bulat Pavel Viktorovich

    2014-01-01

    Full Text Available The research objects of this study are new principles of gas turbine and rocket engines working process organization, based on the oscillatory motion of shock and detonation waves. Purpose is to identify the state of level technology, describe the subject area, state the direction of research and formulate the main problems hindering the implementation of wave technology into mass production. The results presented in the study can be recommended for developers of aircraft engines, power and technological turbo-machinery.

  5. Costs of gunshot and cut/stab wounds in the United States, with some Canadian comparisons.

    Science.gov (United States)

    Miller, T R; Cohen, M A

    1997-05-01

    This article estimates the costs of U.S. gunshot and cut/stab wound by intent. It also compares U.S. to Canadian gunshot experience. Incidence data are from published sources, the National Hospital Ambulatory Medical Care Survey (NHAMCS), and cause-coded emergency department discharge and hospital discharge data systems. Medical care payments and lost earnings per case come from National Crime Survey data, a literature review, and weighting of costs by diagnosis from Databook on Nonfatal Injury-Incidence. Costs, and Consequences by Miller et al. (The Urban Institute Press, Washington, DC. 1995) with the diagnosis distribution of penetrating injuries from the discharge data systems. Quality of life losses are estimated primarily from jury awards to penetrating injury victims. In 1992, gunshots killed 37,776 Americans; cut/stab wounds killed 4095. Another 134,000 gunshot survivors and 3,100,000 cut/stab wound survivors received medical treatment. Annually, gunshot wounds cost an estimated U.S. $126 billion. Cut/stab wounds cost another U.S. $51 billion. The gunshot and cut/stab totals include U.S. $40 billion and U.S. $13 billion respectively in medical, public services, and work-loss costs. Across medically treated cases, costs average U.S. $154,000 per gunshot survivor and U.S. $12,000 per cut/stab survivor. Gunshot wounds are more than three times as common in the U.S. than in Canada, which has strict handgun control. With the same quality of life loss per victim, gunshot costs per capita are an estimated U.S. $495 in the U.S. vs U.S. $180 in Canada. Per gun, however, the costs are higher in Canada, Gunshot wound rates rise linearly with gun ownership. PMID:9183471

  6. Hydrogen-air detonations

    International Nuclear Information System (INIS)

    General gaseous detonation propagation phenomena are briefly discussed. The importance of cellular structure and cell size to detonation initiation, transmission and failure is emphasized. Experimental measurements of cell size lambda for hydrogen-air-carbon dioxide mixtures are presented; the hydrogen/air volume ratios range between 0.16 and 1.5 and the carbon dioxide mole fractions are 0, 0.05, 0.10 and 0.15. Cell sizes are a minimum for both diluted and undiluted hydrogen-air mixtures near stoichiometric (i.e., hydrogen/air = 0.4). Minimum cell sizes for carbon dioxide mole fractions of 0, 0.05, 0.10 and 0.15 are 1.51, 2.05, 4.2 and 15.0 cm, respectively. Results of large- and small-scale critical tube diameter (d/sub c/) measurements are presented and show good agreement with the empirical scaling law, d/sub c/ = 13 lambda. Mean detonation velocities and pressures have been measured and compared to the theoretical Chapman-Jouguet values

  7. Detonation drive pellet injector

    International Nuclear Information System (INIS)

    Detonation drive pellet injector has been developed and tested. By this method the free piston is not necessary because the pellet accelerated the high pressure shock directly. In the experiment, the Teflon pellet (5 mm dia., 5 mm length) was accelerated by hydrogen, oxygen and dilution gas mixtured detonation. When the gas pressure was only 500 kPa and the mixture rates of hydrogen, oxygen and helium were 3:6:1 or 3:6:0, the Teflon pellet speed was up to 747 m/s. Typical experimental results over 300 kPa of the initial gas pressure range are 78--92% of the one-dimensional calculational values. It showed that the pellet could be accelerated by a relative low pressure gas. When the helium dilution rate is larger than 20%, it was often found the strong detonation of which speed is more than the Chapman-Jouguet speed. Then the pellet speed above 1,100 m/s was obtained

  8. Equation of state of HE detonation products

    OpenAIRE

    Nadykto B.A.

    2011-01-01

    Computational analysis of steady-state HE detonation parameters is possible if one knows the equation of state of detonation products and thermal energy released at the Jouget point during detonation. There are a number of equations of state of HE detonation products that result from different assumptions concerning detonated material conditions. The paper considers one more version of the equation of state for HE detonation products.

  9. Detonation Propagation Characteristics of Superposition Explosive Materials

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In order to investigate detonation propagation characteristics of different charge patterns,the detonation velocities of superposition strip-shaped charges made up of a detonating cord and explosives were measured by a detonation velocity measuring instrument under conditions of different ignition.The experimental results and theoretical analysis show that the maximum detonation propagation velocity depends on the explosive materials with the maximum velocity among all the explosive materials.Using detonating cord in a superposition charge can shorten detonation propagation time and improve the efficiency of explosive energy.The measurement method of detonation propagation velocity and experimental results are presented and investigated.

  10. Stabbing headache in an 8-year-old girl: primary or drug induced headache?

    Science.gov (United States)

    Biedroł, Agnieszka; Kaciłski, Marek; Skowronek-Bała, Barbara

    2014-04-01

    The occurrence of stabbing headaches in children requires a thorough diagnostic approach that excludes secondary headaches. The organic background should be taken into consideration when alarming symptoms occur, such as a purely 1-sided location, a change in the character of the headache, or possibly a link to physical activity. The current study describes the case of an 8-year-old girl who suffered short-lasting stabbing headache attacks. The headaches with increasing intensity and frequency started 1 month before her hospitalization and were usually preceded by physical activity (dancing, running). The pain, which was located in the right supraorbital region, lasted 1 second and occurred several times during the day. No associated symptoms were observed. In addition, the girl suffered from allergic rhinitis and was on antiallergic treatment (levocetirizine, fluticasone nasal spray). On admission she was in good general condition, and a pediatric and neurologic examination revealed no abnormalities. Her brain MRI was normal. The initial diagnosis was that the patient was suffering from primary stabbing headaches. However, during a follow-up visit 4 months later, a relationship was observed between the cessation of the headache attacks and the discontinuation of an antihistaminic drug. Six months later, the girl remained headache free. In cases involving differential diagnoses of stabbing headaches, it is important to consider the adverse reactions of the drugs used. PMID:24664098

  11. Pulse Detonation Engine Modeled

    Science.gov (United States)

    Paxson, Daniel E.

    2001-01-01

    Pulse Detonation Engine Technology is currently being investigated at Glenn for both airbreathing and rocket propulsion applications. The potential for both mechanical simplicity and high efficiency due to the inherent near-constant-volume combustion process, may make Pulse Detonation Engines (PDE's) well suited for a number of mission profiles. Assessment of PDE cycles requires a simulation capability that is both fast and accurate. It should capture the essential physics of the system, yet run at speeds that allow parametric analysis. A quasi-one-dimensional, computational-fluid-dynamics-based simulation has been developed that may meet these requirements. The Euler equations of mass, momentum, and energy have been used along with a single reactive species transport equation, and submodels to account for dominant loss mechanisms (e.g., viscous losses, heat transfer, and valving) to successfully simulate PDE cycles. A high-resolution numerical integration scheme was chosen to capture the discontinuities associated with detonation, and robust boundary condition procedures were incorporated to accommodate flow reversals that may arise during a given cycle. The accompanying graphs compare experimentally measured and computed performance over a range of operating conditions for a particular PDE. Experimental data were supplied by Fred Schauer and Jeff Stutrud from the Air Force Research Laboratory at Wright-Patterson AFB and by Royce Bradley from Innovative Scientific Solutions, Inc. The left graph shows thrust and specific impulse, Isp, as functions of equivalence ratio for a PDE cycle in which the tube is completely filled with a detonable hydrogen/air mixture. The right graph shows thrust and specific impulse as functions of the fraction of the tube that is filled with a stoichiometric mixture of hydrogen and air. For both figures, the operating frequency was 16 Hz. The agreement between measured and computed values is quite good, both in terms of trend and

  12. Planar Reflection of Gaseous Detonations

    Science.gov (United States)

    Damazo, Jason Scott

    Pipes containing flammable gaseous mixtures may be subjected to internal detonation. When the detonation normally impinges on a closed end, a reflected shock wave is created to bring the flow back to rest. This study built on the work of Karnesky (2010) and examined deformation of thin-walled stainless steel tubes subjected to internal reflected gaseous detonations. A ripple pattern was observed in the tube wall for certain fill pressures, and a criterion was developed that predicted when the ripple pattern would form. A two-dimensional finite element analysis was performed using Johnson-Cook material properties; the pressure loading created by reflected gaseous detonations was accounted for with a previously developed pressure model. The residual plastic strain between experiments and computations was in good agreement. During the examination of detonation-driven deformation, discrepancies were discovered in our understanding of reflected gaseous detonation behavior. Previous models did not accurately describe the nature of the reflected shock wave, which motivated further experiments in a detonation tube with optical access. Pressure sensors and schlieren images were used to examine reflected shock behavior, and it was determined that the discrepancies were related to the reaction zone thickness extant behind the detonation front. During these experiments reflected shock bifurcation did not appear to occur, but the unfocused visualization system made certainty impossible. This prompted construction of a focused schlieren system that investigated possible shock wave-boundary layer interaction, and heat-flux gauges analyzed the boundary layer behind the detonation front. Using these data with an analytical boundary layer solution, it was determined that the strong thermal boundary layer present behind the detonation front inhibits the development of reflected shock wave bifurcation.

  13. Detonation in supersonic radial outflow

    KAUST Repository

    Kasimov, Aslan R.

    2014-11-07

    We report on the structure and dynamics of gaseous detonation stabilized in a supersonic flow emanating radially from a central source. The steady-state solutions are computed and their range of existence is investigated. Two-dimensional simulations are carried out in order to explore the stability of the steady-state solutions. It is found that both collapsing and expanding two-dimensional cellular detonations exist. The latter can be stabilized by putting several rigid obstacles in the flow downstream of the steady-state sonic locus. The problem of initiation of standing detonation stabilized in the radial flow is also investigated numerically. © 2014 Cambridge University Press.

  14. Thermodynamic Cycle Analysis for Propagating Detonations

    OpenAIRE

    Wintenberger, E.; Shepherd, J. E.

    2006-01-01

    Propagating detonations have recently been the focus of extensive work based on their use in pulse detonation engines [1]. The entropy minimum associated with Chapman–Jouguet (CJ) detonations [2] and its potential implications on the thermal efficiency of these systems [3] has been one of the main motivations for these efforts. The notion of applying thermodynamic cycles to detonation was considered first by Zel’dovich [4], who concluded that the efficiency of the detonation cycle is slightly...

  15. Exophytic benign prostatic hyperplasia.

    Science.gov (United States)

    Blaschko, Sarah D; Eisenberg, Michael L

    2011-08-01

    A 60-year-old man had incidental finding of a multilobular 8 × 7 × 7-cm mass identified posterior to the urinary bladder in continuity with the prostate. The man's prostate-specific antigen was 1.87, and he denied any lower urinary tract symptoms. A transrectal ultrasound-guided biopsy demonstrated benign prostatic tissue. A computed tomography-guided needle aspiration demonstrated a benign epithelium-lined cyst, likely prostatic in origin. Benign prostatic hyperplasia is a proliferation of prostatic epithelial and stromal cells. Although prostatic hyperplasia is usually restricted to the prostate gland, hyperplastic nodules occasionally protrude outside the prostate and rarely form exophytic pelvic masses. PMID:20869104

  16. Applications of classical detonation theory

    Energy Technology Data Exchange (ETDEWEB)

    Davis, W.C.

    1994-09-01

    Classical detonation theory is the basis for almost all calculations of explosive systems. One common type of calculation is of the detailed behavior of inert parts driven by explosive, predicting pressures, velocities, positions, densities, energies, etc as functions of time. Another common application of the theory is predicting the detonation state and expansion isentrope of a new explosive or mixtures, perhaps an explosive that has not yet been made. Both types of calculations are discussed.

  17. STABILITY OF PLASMIDS IN 5 STRAINS OF SALMONELLA MAINTAINED IN STAB CULTURE AT DIFFERENT TEMPERATURES

    DEFF Research Database (Denmark)

    Olsen, J. E.; Brown, D. J.; Baggesen, Dorte Lau;

    1994-01-01

    Four strains of Salmonella berta and one of Salm. enteritidis were stored as stab cultures in sugar-free agar at 5 degrees, 22 degrees and 30 degrees C and in 15% glycerol at -80 degrees C. The stability of the plasmid profiles in each of the strains was monitored over a period of 2.5 years....... Plasmid profiles were stable in all strains stored at -80 degrees C, and only six of 450 colonies examined from strains kept in sugar-free agar at 5 degrees C had lost plasmid molecules. Seventy of 440 colonies from stab cultures that were kept at 22 degrees C, and 71 of 440 colonies at 30 degrees C...... showed changed plasmid profiles. The total number of plasmids lost increased with time, and occasionally, more than one plasmid molecule was lost in the same strain. The virulence associated plasmid of Salm. enteritidis was remarkably stable as it was maintained in all colonies examined at all...

  18. REVERSIBLE CORTICAL BLINDNESS FOLLOWING SUCCESSFUL SURGICAL REPAIR OF TWO STAB WOUNDS IN THE HEART

    Directory of Open Access Journals (Sweden)

    Zaiton A

    2008-01-01

    Full Text Available This report describes a case of cortical blindness that followed successful surgical repair of two stab wounds in the heart in a 29-year old Libyan man. The patient presented in a state of pre cardiac arrest (shock and low cardiac output status, following multiple chest stab wounds. Chest tube was immediately inserted. Surgery was urgently performed suturing the two wounds; in the root of the aorta and in the left ventricle, and haemostasis was secured. Cardiac arrest was successfully prevented. The patient recovered smoothly, but 24 hours later he declared total blindness. Ophtalmic and neurological examinations and investigations that included fundoscopy, Electroencephalograms (EEGs and Computed Tomography Scans revealed no abnormalities, apart from absence of alpha waves in the EEGs. We diagnosed the case as cortical blindness and continued caring for the patient conservatively. Three days later, the patient regained his vision gradually and was discharged on the 7th postoperative day without any remarks.

  19. Benign focal hepatic lesions; Benigne fokale Leberlaesionen

    Energy Technology Data Exchange (ETDEWEB)

    Baroud, S.; Bastati, N.; Prosch, H.; Ba-Ssalamah, A. [AKH, Medizinische Universitaet Wien, Universitaetsklinik fuer Radiodiagnostik, Wien (Austria); Schima, W. [Krankenhaus Goettlicher Heiland, Wien, Abteilung fuer Radiologie und Bildgebende Diagnostik, Wien (Austria)

    2011-08-15

    A profound knowledge of the various benign focal hepatic lesions and selection of the most suitable radiological examination modality is essential for achieving an accurate characterization of a hepatic lesion and in turn will determine the further patient management. This will avoid unnecessary agitation to both patient and the referring clinician and limits time-consuming, costly and risky biopsies to an absolute minimum. The following article will discuss the typical and atypical appearances of the most frequent and clinically relevant benign focal hepatic lesions with ultrasound, computed tomography and magnetic resonance imaging. (orig.) [German] Eine genaue Kenntnis des breiten Spektrums benigner fokaler Leberlaesionen und der geeigneten radiologischen Untersuchungsmethode ist essenziell, um eine sichere Diagnose bzgl. der Dignitaet und damit das weitere Vorgehen bestimmen zu koennen. Damit wird eine unnoetige Verunsicherung des Patienten und des behandelnden Arztes vermieden, und invasive, eventuell mit Komplikationen assoziierte Biopsien sowie zeit- und kostenintensive Verlaufskontrollen koennen reduziert werden. Der folgende Artikel erlaeutert die haeufigsten und klinisch wichtigsten benignen fokalen Leberlaesionen und deren typisches und atypisches Erscheinen in den 3 haeufig verwendeten bildgebenden Verfahren Sonographie, Computertomographie und Magnetresonanztomographie. (orig.)

  20. Astrocyte morphology after cortical stab wound revealed by single-cell confocal 3D morphometry

    Czech Academy of Sciences Publication Activity Database

    Chvátal, Alexandr; Anděrová, Miroslava; Petřík, David; Syková, Eva

    č. 2 (2003), s. 63. ISSN 0894-1491. [European Meeting on Glial Cell Function in Health and Disease /6./. Berlín, 03.09.2003-06.09.2003] R&D Projects: GA ČR GA305/02/1528; GA MŠk LN00A065 Institutional research plan: CEZ:AV0Z5039906; CEZ:MSM 111300004 Keywords : cortical stab wound * morphometry Subject RIV: FH - Neurology Impact factor: 4.677, year: 2003

  1. Differences between postmortem computed tomography and conventional autopsy in a stabbing murder case

    OpenAIRE

    Zerbini, Talita; da Silva, Luiz Fernando Ferraz; Ferro, Antonio Carlos Gonçalves; Kay, Fernando Uliana; Junior, Edson Amaro; Pasqualucci, Carlos Augusto Gonçalves; do Nascimento Saldiva, Paulo Hilario

    2014-01-01

    OBJECTIVE: The aim of the present work is to analyze the differences and similarities between the elements of a conventional autopsy and images obtained from postmortem computed tomography in a case of a homicide stab wound. METHOD: Comparison between the findings of different methods: autopsy and postmortem computed tomography. RESULTS: In some aspects, autopsy is still superior to imaging, especially in relation to external examination and the description of lesion vitality. However, the fi...

  2. Differences between postmortem computed tomography and conventional autopsy in a stabbing murder case

    OpenAIRE

    Talita Zerbini; Luiz Fernando Ferraz da Silva; Antonio Carlos Gonçalves Ferro; Fernando Uliana Kay; Edson Amaro Junior; Carlos Augusto Gonçalves Pasqualucci; Paulo Hilario do Nascimento Saldiva

    2014-01-01

    Objective: The aim of the present work is to analyze the differences and similarities between the elements of a conventional autopsy and images obtained from postmortem computed tomography in a case of a homicide stab wound. Method: Comparison between the findings of different methods: autopsy and postmortem computed tomography. Results: In some aspects, autopsy is still superior to imaging, especially in relation to external examination and the description of lesion vitality. However, th...

  3. Difficult Airway due to Retropharyngeal Hematoma after Stabbing to the Neck

    Directory of Open Access Journals (Sweden)

    Kouhei Iwashita

    2014-07-01

    Full Text Available Reports of retropharyngeal hematoma have been scarce in the anesthesiology literature. We report a patient whose trachea was difficult to intubate due to retropharyngeal hematoma after stabbing to the neck. A woman with a knife injury to the common carotid artery required emergency carotid arterioplasty. When tracheal intubation was attempted, marked swelling of the posterior pharyngeal wall made the vocal cords impossible to visualize. Preoperative computed tomography showed a retropharyngeal hematoma. The patient required mechanical ventilation for 2 days.

  4. IP-telefon säästab oluliselt sidekulusid / Kristjan Otsmann

    Index Scriptorium Estoniae

    Otsmann, Kristjan, 1971-

    2005-01-01

    Telekomifirma Norby Telecomi poolt pakutavast IP-telefonist ehk helistamisest läbi Interneti, millega saab vähendada sidekulusid mitmeid kordi. Erinevatest internetipõhise kõnesidelahenduse lisateenustest. Vt. samas: Saaremaa Spa Hotellid säästab tuhandeid kroone kuus [intervjuu Saaremaa Spa Hotellide IT-juhiga Andri Võrguga]; Kuus olulist tööd enne IP-lahenduse tellimist

  5. Benign positional vertigo - aftercare

    Science.gov (United States)

    Vertigo - positional - aftercare; Benign paroxysmal positional vertigo - aftercare; BPPV - aftercare ... Your doctor may have treated your vertigo with the Epley maneuver. ... ear problem that causes BPPV. It usually works quickly. For ...

  6. Point Measurement of Detonation Wave Speed

    Science.gov (United States)

    Lu, F. K.; Gupta, N. K. M.; Wilson, D. R.

    Accurate determination of the speed of a detonation wave is important for studies of detonation phenomena. Different types of sensors that measure pressure, ion and flame have been used for this purpose.

  7. NONEL High Precision MS Delay Detonator

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The NONEL high precision MS Delay Detonator (FDG-1detonator) is introduced. The main aspects about the FDG-1 detonator include the choice of structure, delay composition, control of the gas chamber, o ptimum charge and density, suitable explosives per meter in the NONEL tube, base firing charge and the main specifications. The improvement of the characteristics of FDG-1 detonator has been tested systematical ly. The testing method is reliable and its precision can meet the dema nd for usage.

  8. Benign cystic peritoneal mesothelioma

    Directory of Open Access Journals (Sweden)

    Santhosh Shetty

    2014-04-01

    Full Text Available A well-defined but rare entity of Benign Cystic Peritoneal Mesothelioma (BCPM is reported. The aetiology of this neoplasm remains obscure. The presenting features make a precise preoperative diagnosis difficult but information provided by computed tomography and cytology may help. A firm diagnosis can only come from an electronic microscopy or immunohistological examination of the tumour. Diagnostic accuracy and diligent follow up are essential because, although the tumour is considered benign, it does tend towards local recurrence. [Int J Res Med Sci 2014; 2(2.000: 762-764

  9. Stab injury and device implantation within the brain results in inversely multiphasic neuroinflammatory and neurodegenerative responses

    Science.gov (United States)

    Potter, Kelsey A.; Buck, Amy C.; Self, Wade K.; Capadona, Jeffrey R.

    2012-08-01

    An estimated 25 million people in the US alone rely on implanted medical devices, ˜2.5 million implanted within the nervous system. Even though many devices perform adequately for years, the host response to medical devices often severely limits tissue integration and long-term performance. This host response is believed to be particularly limiting in the case of intracortical microelectrodes, where it has been shown that glial cell encapsulation and localized neuronal cell loss accompany intracortical microelectrode implantation. Since neuronal ensembles must be within ˜50 µm of the electrode to obtain neuronal spikes and local field potentials, developing a better understanding of the molecular and cellular environment at the device-tissue interface has been the subject of significant research. Unfortunately, immunohistochemical studies of scar maturation in correlation to device function have been inconclusive. Therefore, here we present a detailed quantitative study of the cellular events and the stability of the blood-brain barrier (BBB) following intracortical microelectrode implantation and cortical stab injury in a chronic survival model. We found two distinctly inverse multiphasic profiles for neuronal survival in device-implanted tissue compared to stab-injured animals. For chronically implanted animals, we observed a biphasic paradigm between blood-derived/trauma-induced and CNS-derived inflammatory markers driving neurodegeneration at the interface. In contrast, stab injured animals demonstrated a CNS-mediated neurodegenerative environment. Collectively these data provide valuable insight to the possibility of multiple roles of chronic neuroinflammatory events on BBB disruption and localized neurodegeneration, while also suggesting the importance to consider multiphasic neuroinflammatory kinetics in the design of therapeutic strategies for stabilizing neural interfaces.

  10. Benign Fibrous Histiocytoma

    Directory of Open Access Journals (Sweden)

    Pushpa Varma

    2014-01-01

    Full Text Available Fibrous histiocytomas (FHs are mesenchymal tumors that may be benign or malignant. Ocular involvement by FHs is infrequent and primarily limited to the orbit. Rarely, FHs can also involve the conjunctiva and perilimbal area. We report the case of a 38-year-old male with lid, conjunctival, and neck FHs. The diagnosis was confirmed by histopathology.

  11. Benign gastric filling defect

    International Nuclear Information System (INIS)

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  12. Prehospital ultrasound detects pericardial tamponade in a pregnant victim of stabbing assault.

    Science.gov (United States)

    Byhahn, Christian; Bingold, Tobias M; Zwissler, Bernhard; Maier, Marcus; Walcher, Felix

    2008-01-01

    The development of handheld, portable ultrasound devices has enabled the use of this diagnostic tool also in the out-of-hospital environment. We report on a pregnant teenager who was found haemodynamically unstable after a stab assault. When she suffered cardiac arrest shortly thereafter, diagnosis of cardiac tamponade was made by portable ultrasound, and immediate pericardiocentesis was performed by the emergency physician. While her baby died after emergency Caesarean section, the teenager survived after thoracotomy and prolonged resuscitation without neurological sequelae. PMID:17716805

  13. Quantification of forces required for stabbing with screwdrivers and other blunter instruments.

    Science.gov (United States)

    Parmar, Kiran; Hainsworth, Sarah Victoria; Rutty, Guy Nathan

    2012-01-01

    In the UK, stabbing is the most common cause of homicide. The weapons used include knives, swords, screwdrivers and glass shards. Quantifying the exact force used in a stabbing incident is considered to be a difficult area due to the large number of variables present, such as sharpness of weapon, angle of attack and relative movements of the people involved. Having quantifiable data would allow a forensic pathologist to make a more informed decision when it comes to answering the commonly posed question in court "what was the degree of force involved in the stabbing incident?" The answer to this question is considered significant in determining an alleged assailant's intent to cause harm. This paper presents results of the first detailed study relating geometry of screwdrivers to the forces required for penetration. Additionally, a range of other blunt weapons such as pens and chisels have also been studied. A silicone rubber-foam analogue has been used as the main skin simulant owing to it having similar mechanical properties to that of human skin and giving highly repeatable results. Different screwdrivers of varying shape and size have been tested (i.e. slotted, Phillips, posidriv and Torx), along with other implements including chisels and pens. The weapon geometry was characterised and related to the peak force required for penetration. Our results show that there is a direct correlation between the cross-sectional area of a screwdriver head and the amount of force required for penetration. Screwdrivers with larger cross-sectional areas require a significantly greater force to penetrate (forces in the region of 100-120 N) but "sharper" slotted screwdrivers penetrate with much lower forces (~30 N). The forces required for penetrating the rubber-foam analogue with screwdrivers are higher than for "sharp" knives, but in some cases similar to the forces required for stabbing with "blunt" knives. For the other weapons such as chisels and biros, the force required

  14. Detonation of hydrogen-air mixtures

    International Nuclear Information System (INIS)

    The detonation of a hydrogen-air cloud subsequent to an accidental release of hydrogen into ambient surroundings cannot be totally ruled out in view of the relative sensitivity of the hydrogen-air system. The present paper investigates the key parameters involved in hydrogen-air detonations and attempts to establish quantitative correlations between those that have important practical implications. Thus, for example, the characteristic length scale lambda describing the cellular structure of a detonation front is measured for a broad range of hydrogen-air mixtures and is quantitatively correlated with the key dynamic detonation properties such as detonability, transmission and initiation

  15. Turbulent deflagrations, autoignitions, and detonations

    KAUST Repository

    Bradley, Derek

    2012-09-01

    Measurements of turbulent burning velocities in fan-stirred explosion bombs show an initial linear increase with the fan speed and RMS turbulent velocity. The line then bends over to form a plateau of high values around the maximum attainable burning velocity. A further increase in fan speed leads to the eventual complete quenching of the flame due to increasing localised extinctions because of the flame stretch rate. The greater the Markstein number, the more readily does flame quenching occur. Flame propagation along a duct closed at one end, with and without baffles to increase the turbulence, is subjected to a one-dimensional analysis. The flame, initiated at the closed end of the long duct, accelerates by the turbulent feedback mechanism, creating a shock wave ahead of it, until the maximum turbulent burning velocity for the mixture is attained. With the confining walls, the mixture is compressed between the flame and the shock plane up to the point where it might autoignite. This can be followed by a deflagration to detonation transition. The maximum shock intensity occurs with the maximum attainable turbulent burning velocity, and this defines the limit for autoignition of the mixture. For more reactive mixtures, autoignition can occur at turbulent burning velocities that are less than the maximum attainable one. Autoignition can be followed by quasi-detonation or fully developed detonation. The stability of ensuing detonations is discussed, along with the conditions that may lead to their extinction. © 2012 by Pleiades Publishing, Ltd.

  16. Initiation of detonation in supernovae

    International Nuclear Information System (INIS)

    The formation of the thermonuclear burning front is considered under the explosion of degenerate CO-star as a supernova. It is shown that the thermal instability leads to the detonation if the initial central temperature profile is isentropic one (instead of the widely accepted deflagration regime of burning)

  17. Pulse detonation engines and components thereof

    Science.gov (United States)

    Tangirala, Venkat Eswarlu (Inventor); Rasheed, Adam (Inventor); Vandervort, Christian Lee (Inventor); Dean, Anthony John (Inventor)

    2009-01-01

    A pulse detonation engine comprises a primary air inlet; a primary air plenum located in fluid communication with the primary air inlet; a secondary air inlet; a secondary air plenum located in fluid communication with the secondary air inlet, wherein the secondary air plenum is substantially isolated from the primary air plenum; a pulse detonation combustor comprising a pulse detonation chamber, wherein the pulse detonation chamber is located downstream of and in fluid communication with the primary air plenum; a coaxial liner surrounding the pulse detonation combustor defining a cooling plenum, wherein the cooling plenum is in fluid communication with the secondary air plenum; an axial turbine assembly located downstream of and in fluid communication with the pulse detonation combustor and the cooling plenum; and a housing encasing the primary air plenum, the secondary air plenum, the pulse detonation combustor, the coaxial liner, and the axial turbine assembly.

  18. Study of detonation wave contours in EFP warhead

    OpenAIRE

    Xu-dong Zu; Zheng-xiang Huang; Chuan-sheng Zhu; Qiang-qiang Xiao

    2016-01-01

    An analytical model for calculating the propagation time of shock wave in a wave shaper is presented in this study. The calculated results show that the contours of three typical detonation waves, such as conical detonation wave, spherical detonation wave, and planar detonation wave, can be formed in the main charge by changing the thickness of wave shaper. The results show that the planar detonation wave do better than the conical detonation and the spherical detonation wave in increasing...

  19. Suicide by self-inflicted stab wound to the heart: a rare case of suicide from Nepal

    OpenAIRE

    Jha, S.; SR Parajuli; ND Subedi

    2015-01-01

    Suicide, or the deliberate act of killing oneself, accounts for a substantial number of unnatural deaths each year in many countries. Though death by self-stabbing is quite uncommon, the left part of the chest represents one of the elected sites of self-inflicted wounds because of the knowledge of the situation of the heart and that the injuries to the heart are severe. We present a case of suicidal stab to the left thoracic region involving the heart.DOI: http://dx.doi.org/10.3126/jcmsn.v10i...

  20. Benign metastasizing leiomyoma

    Directory of Open Access Journals (Sweden)

    Fatima Saira

    2010-10-01

    Full Text Available Benign metastasizing leiomyoma (BML is a rare condition, affecting predominantly reproductive-age females with uterine leiomyomata and is most often associated with multiple benign-appearing smooth muscle tumors in lungs. We report herein a case of a 38-year-old woman who presented with multiple uterine fibroids for which hysterectomy was carried out on her. Postoperatively, she developed left-sided pleural effusion. Computed chest tomography (CT scan revealed multiple nodules in both lungs and pleurae. Histopathology of one of the pleura-based nodules revealed a neoplasm composed of interlacing fascicles of spindle cells with uniform nuclei. The tumor cells were positive for alpha-smooth muscle actin and negative for CD34 immunohistochemical stain.

  1. Benign metastasizing leiomyoma.

    Science.gov (United States)

    Fatima, Saira; Ahmed, Zubair; Azam, Mohammad

    2010-01-01

    Benign metastasizing leiomyoma (BML) is a rare condition, affecting predominantly reproductive-age females with uterine leiomyomata and is most often associated with multiple benign-appearing smooth muscle tumors in lungs. We report herein a case of a 38-year-old woman who presented with multiple uterine fibroids for which hysterectomy was carried out on her. Postoperatively, she developed left-sided pleural effusion. Computed chest tomography (CT) scan revealed multiple nodules in both lungs and pleurae. Histopathology of one of the pleura-based nodules revealed a neoplasm composed of interlacing fascicles of spindle cells with uniform nuclei. The tumor cells were positive for alpha-smooth muscle actin and negative for CD34 immunohistochemical stain. PMID:21045423

  2. Infantile benign subdural effusion

    International Nuclear Information System (INIS)

    Twenty cases of infants with low density area over the frontal lobes on CT scans mimicking cortical atrophy were reported. Almost all cases showed increased intracranial pressure of slight degree associated with delayed milestones. Marginal low density over the frontal lobes disappeared and the infants developed almost normally without operations in many cases. The lesion might be called ''Infantile benign subdural effusion'' and should be treated conservatively. (author)

  3. Benign pneumatosis in children

    Energy Technology Data Exchange (ETDEWEB)

    Fenton, L.Z.; Buonomo, C. [Department of Radiology, Children' s Hospital, Boston, MA (United States)

    2000-11-01

    Background. In pediatrics, pneumatosis intestinalis (PI) is usually due to necrotizing enterocolitis in premature newborns. Beyond infancy, PI is uncommon. ''Benign pneumatosis'' is PI in patients with few or no symptoms that resolves with conservative management. Objective. Our goal was to better characterize benign PI in children. Our investigation focused on identifying underlying risk factors, symptoms at time of diagnosis, management and outcome. Materials and methods. Available medical records and radiographs of children with pneumatosis intestinalis from 1990 to 1998 were reviewed for underlying conditions, symptoms at time of radiographs, management and outcome. Results. Thirty-seven children (mean age 4 years) were included. Thirty-two children had identifiable risk factors. Twenty -five children were immunocompromised by their underlying conditions or therapeutic regimen. Thirty-five children were managed conservatively with resolution of PI. Two patients, however, required surgery and one patient died. Conclusion. Benign pneumatosis does occur in children. The majority have underlying risk factors, most commonly related to immunosuppression. Clinical deterioration is the most useful indicator for surgical intervention. In most patients PI resolves with conservative management. (orig.)

  4. Detonation interaction with an interface

    OpenAIRE

    Lieberman, D. H.; Shepherd, J. E.

    2007-01-01

    Detonation interaction with an interface was investigated, where the interface separated a combustible from an oxidizing or inert mixture. The ethylene-oxygen combustible mixture had a fuel-rich composition to promote secondary combustion with the oxidizer in the turbulent mixing zone (TMZ) that resulted from the interaction. Sharp interfaces were created by using a nitro-cellulose membrane to separate the two mixtures. The membrane was mounted on a wood frame and inserted in the experimental...

  5. Transarterial coil embolization in treatment of gross hematuria following self-inflicted stab wound in a horseshoe kidney

    Institute of Scientific and Technical Information of China (English)

    Masoud Pezeshki Rad; Hassan Ahmadnia; Mahboobeh Abedi; Mohammad Sadegh Abedi

    2012-01-01

    Horseshoe kidney is an uncommon anomaly of the urinary system with an increased risk of injury during penetrating and blunt abdominal traumas.Selfinflicted abdominal stab wound,a rare type of abdominal injury,accounts for only a small percentage of suicidal attempts and may be infrequently encountered by physicians in trauma centers.Psychiatric disorders and alcohol or drug abuse are common risk factors in cases of self-stabbing.Here we report a rare case of self-stabbing of a horseshoe kidney.The case was a 19-year-old man with self-inflicted abdominal stab wound who was referred to our department of radiology due to re-occurred gross hematuria three days after exploratory laparotomy and surgical repair of injured abdominal organs.A horseshoe kidney was incidentally found in the patient's abdominal computed tomography.Renal angiography revealed active contrast extravasation from one of the segmental arteries.Selective transarterial embolization with a coil was successfully performed to control the hematuria.

  6. Radiotherapy of benign diseases

    International Nuclear Information System (INIS)

    Still today radiotherapy is of decisive relevance for several benign diseases. The following ones are briefly described in this introductory article: 1. Certain inflammatory and degenerative diseases as furuncles in the face, acute thrombophlebitis, recurrent sudoriparous abscesses, degenerative skeletal diseases, cervical syndrome and others; 2. rheumatic joint diseases; 3. Bechterew's disease; 4. primary presenile osteoporosis; 5. synringomyelia; 6. endocrine ophthalmopathy; 7. hypertrophic processes of the connective tissue; 8. hemangiomas. A detailed discussion and a profit-risk analysis is provided in the individual chapters of the magazine. (MG)

  7. Deflagrations and Detonations in Thermonuclear Supernovae

    CERN Document Server

    Gamezo, V N; Oran, E S; Gamezo, Vadim N.; Khokhlov, Alexei M.; Oran, Elaine S.

    2004-01-01

    We study a type Ia supernova explosion using three-dimensional numerical simulations based on reactive fluid dynamics. We consider a delayed-detonation model that assumes a deflagration-to-detonation transition. In contrast to the pure deflagration model, the delayed-detonation model releases enough energy to account for a healthy explosion, and does not leave carbon, oxygen, and intermediate-mass elements in central parts of a white dwarf. This removes the key disagreement between simulations and observations, and makes a delayed detonation the mostly likely mechanism for type Ia supernovae.

  8. A summary of hydrogen-air detonation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Guirao, C.M.; Knystautas, R.; Lee, J.H.

    1989-05-01

    Dynamic detonation parameters are reviewed for hydrogen-air-diluent detonations and deflagration-to-detonation transitions (DDT). These parameters include the characteristic chemical length scale, such as the detonation cell width, associated with the three-dimensional cellular structure of detonation waves, critical transmission conditions of confined detonations into unconfined environments, critical initiation energy for unconfined detonations, detonability limits, and critical conditions for DDT. The detonation cell width, which depends on hydrogen and diluent concentrations, pressure, and temperature, is an important parameter in the prediction of critical geometry-dependent conditions for the transmission of confined detonations into unconfined environments and the critical energies for the direct initiation of unconfined detonations. Detonability limits depend on both initial and boundary conditions and the limit has been defined as the onset of single head spin. Four flame propagation regimes have been identified and the criterion for DDT in a smooth tube is discussed. 108 refs., 28 figs., 5 tabs.

  9. A summary of hydrogen-air detonation experiments

    International Nuclear Information System (INIS)

    Dynamic detonation parameters are reviewed for hydrogen-air-diluent detonations and deflagration-to-detonation transitions (DDT). These parameters include the characteristic chemical length scale, such as the detonation cell width, associated with the three-dimensional cellular structure of detonation waves, critical transmission conditions of confined detonations into unconfined environments, critical initiation energy for unconfined detonations, detonability limits, and critical conditions for DDT. The detonation cell width, which depends on hydrogen and diluent concentrations, pressure, and temperature, is an important parameter in the prediction of critical geometry-dependent conditions for the transmission of confined detonations into unconfined environments and the critical energies for the direct initiation of unconfined detonations. Detonability limits depend on both initial and boundary conditions and the limit has been defined as the onset of single head spin. Four flame propagation regimes have been identified and the criterion for DDT in a smooth tube is discussed. 108 refs., 28 figs., 5 tabs

  10. Diagnosis and Treatment of Penetrating Cardiac Injury One Year after Thoracic Stab Wound

    Directory of Open Access Journals (Sweden)

    MH Soltani

    2005-10-01

    Full Text Available In any patient with a history of penetrating thoracic trauma, cardiac injury must be kept in mind. Here, we describe a 36 years-old female referred to this hospital with severe chest pain and hypotension. After primary evaluation and suggestion of AMI, streptokinase was started for the patient and because of deterioration of vital signs, cardiac surgery consultation was requested. After performing urgent echocardiography, massive pericardial tamponade was detected. Visualization of a knife blade on C.X.R and past medical history of thoracic stab injury led to a diagnosis of delayed cardiac tamponade and urgent sternotomy was performed. The blade that had penetrated the right ventricular chamber was extracted. Six days after operation, patient was discharged without any problem. This case study suggests the importance of high suspicion to cardiac injury in any patient with chest pain and a history of chest trauma.

  11. Differences between postmortem computed tomography and conventional autopsy in a stabbing murder case

    Directory of Open Access Journals (Sweden)

    Talita Zerbini

    2014-12-01

    Full Text Available Objective: The aim of the present work is to analyze the differences and similarities between the elements of a conventional autopsy and images obtained from postmortem computed tomography in a case of a homicide stab wound. Method: Comparison between the findings of different methods: autopsy and postmortem computed tomography. Results: In some aspects, autopsy is still superior to imaging, especially in relation to external examination and the description of lesion vitality. However, the findings of gas embolism, pneumothorax and pulmonary emphysema and the relationship between the internal path of the instrument of aggression and the entry wound are better demonstrated by postmortem computed tomography. Conclusions: Although multislice computed tomography has greater accuracy than autopsy, we believe that the conventional autopsy method is fundamental for providing evidence in criminal investigations.

  12. Review on Recent Advances in Pulse Detonation Engines

    OpenAIRE

    Pandey, K. M.; Pinku Debnath

    2016-01-01

    Pulse detonation engines (PDEs) are new exciting propulsion technologies for future propulsion applications. The operating cycles of PDE consist of fuel-air mixture, combustion, blowdown, and purging. The combustion process in pulse detonation engine is the most important phenomenon as it produces reliable and repeatable detonation waves. The detonation wave initiation in detonation tube in practical system is a combination of multistage combustion phenomena. Detonation combustion causes rapi...

  13. Spinal Cord Injury Caused by Stab Wounds: Incidence, Natural History, and Relevance for Future Research.

    Science.gov (United States)

    McCaughey, Euan J; Purcell, Mariel; Barnett, Susan C; Allan, David B

    2016-08-01

    Spinal cord injury caused by stab wounds (SCISW) results from a partial or complete transection of the cord, and presents opportunities for interventional research. It is recognized that there is low incidence, but little is known about the natural history or the patient's suitability for long-term clinical outcome studies. This study aims to provide population-based evidence of the demographics of SCISW, and highlight the issues regarding the potential for future research. The database of the Queen Elizabeth National Spinal Injuries Unit (QENSIU), the sole center for treating SCI in Scotland, was reviewed between 1994 and 2013 to ascertain the incidence, demographics, functional recovery, and mortality rates for new SCISW. During this 20 year period, 35 patients with SCISW were admitted (97.1% male, mean age 30.0 years); 31.4% had a cervical injury, 60.0% had a thoracic injury, and 8.6% had a lumbar injury. All had a neurological examination, with 42.9% diagnosed as motor complete on admission and 77.1% discharged as motor incomplete. A total of 70.4% of patients with an American Spinal Injury Association Impairment Scale (AIS) level of A to C on admission had an improved AIS level on discharge. Nine (25.7%) patients have died since discharge, with mean life expectancy for these patients being 9.1 years after injury (20-65 years of age). Patients had higher levels of comorbidities, substance abuse, secondary events, and poor compliance compared with the general SCI population, which may have contributed to the high mortality rate observed post-discharge. The low incidence, heterogeneous nature, spontaneous recovery rate, and problematic follow-up makes those with penetrating stab injuries of the spinal cord a challenging patient group for SCI research. PMID:26825180

  14. Detonation diffraction through different geometries

    Science.gov (United States)

    Sorin, Rémy; Zitoun, Ratiba; Khasainov, Boris; Desbordes, Daniel

    2009-04-01

    We performed the study of the diffraction of a self-sustained detonation from a cylindrical tube (of inner diameter d) through different geometric configurations in order to characterise the transmission processes and to quantify the transmission criteria to the reception chamber. For the diffraction from a tube to the open space the transmission criteria is expressed by d c = k c · λ (with λ the detonation cell size and k c depending on the mixture and on the operture configuration, classically 13 for alkane mixtures with oxygen). The studied geometries are: (a) a sharp increase of diameter ( D/ d > 1) with and without a central obstacle in the diffracting section, (b) a conical divergent with a central obstacle in the diffracting section and (c) an inversed intermediate one end closed tube insuring a double reflection before a final diffraction between the initiator tube and the reception chamber. The results for case A show that the reinitiation process depends on the ratio d/ λ. For ratios below k c the re-ignition takes place at the receptor tube wall and at a fixed distance from the step, i.e. closely after the diffracted shock reflection shows a Mach stem configuration. For ratios below a limit ratio k lim (which depends on D/ d) the re-ignition distance increases with the decrease of d/λ. For both case A and B the introduction of a central obstacle (of blockage ratio BR = 0.5) at the exit of the initiator tube decreases the critical transmission ratio k c by 50%. The results in configuration C show that the re-ignition process depends both on d/ λ and the geometric conditions. Optimal configuration is found that provides the transmission through the two successive reflections (from d = 26 mm to D ch = 200 mm) at as small d/ λ as 2.2 whatever the intermediate diameter D is. This configuration provides a significant improvement in the detonation transmission conditions.

  15. Detonation capturing for stiff combustion chemistry

    NARCIS (Netherlands)

    Berkenbosch, A.C.; Kaasschieter, E.F.; Klein, R.

    1998-01-01

    This paper contributes to the topic of unphysical one-cell-per-time-step travelling combustion wave solutions in numerical computations of detonation waves in the presence of stiff chemical source terms. These false weak detonation solutions appear when a gas-dynamics-chemistry operator-splitting te

  16. VELOCITY OF DETONATION OF LOW DENSITY

    Directory of Open Access Journals (Sweden)

    Vinko Škrlec

    2012-12-01

    Full Text Available Blasting operations in built-up areas, at short distances from structures, impose new requirements on blasting techniques and properties of explosives in order to mitigate seismic effect of blasting. Explosives for civil uses are mixtures of different chemical composition of explosive and/or non-explosive substances. Chemical and physical properties, along with means of initiation, environment and the terms of application define detonation and blasting parameters of a particular type of the explosive for civil uses. Velocity of detonation is one of the most important measurable characteristics of detonation parameters which indirectly provide information about the liberated energy, quality of explosives and applicability for certain purposes. The level of shock effect of detonated charge on the rock, and therefore the level of seismic effect in the area, depends on the velocity of detonation. Since the velocity of detonation is proportional to the density of an explosive, the described research is carried out in order to determine the borderline density of the mixture of an emulsion explosive with expanded polystyrene while achieving stable detonation, and to determine the dependency between the velocity of detonation and the density of mixture (the paper is published in Croatian.

  17. 14 CFR 33.47 - Detonation test.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Detonation test. 33.47 Section 33.47 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.47 Detonation test. Each...

  18. Pulse detonation assembly and hybrid engine

    Science.gov (United States)

    Rasheed, Adam (Inventor); Dean, Anthony John (Inventor); Vandervort, Christian Lee (Inventor)

    2010-01-01

    A pulse detonation (PD) assembly includes a number of PD chambers adapted to expel respective detonation product streams and a number of barriers disposed between respective pairs of PD chambers. The barriers define, at least in part, a number of sectors that contain at least one PD chamber. A hybrid engine includes a number of PD chambers and barriers. The hybrid engine further includes a turbine assembly having at least one turbine stage, being in flow communication with the PD chambers and being configured to be at least partially driven by the detonation product streams. A segmented hybrid engine includes a number of PD chambers and segments configured to receive and direct the detonation product streams from respective PD chambers. The segmented hybrid engine further includes a turbine assembly configured to be at least partially driven by the detonation product streams.

  19. Detonation wave initiation of ram accelerator propellants

    Science.gov (United States)

    Bauer, P.; Knowlen, C.

    The current ram accelerator operations have shown that data on the ability of the propellants to detonate are required. Previous studies examined the efficacy of initiation techniques based on piston impact. The purpose of the present work is to analyze the effects of detonation wave transmission from a detonating mixture into a low sensitivity mixture. One-dimensional modeling based on the analysis of pressure vs particle velocity for the mixtures is used to interpret experimental data. Furthermore, calculations based on chemical kinetics (CHEMKIN code) are provided. Experimental data together with the modeling of the detonation transmission provide some new insight into the limiting conditions necessary to establish a Chapman-Jouguet (CJ) wave in a detonable mixture.

  20. Molecular dynamics simulations of weak detonations.

    Science.gov (United States)

    Am-Shallem, Morag; Zeiri, Yehuda; Zybin, Sergey V; Kosloff, Ronnie

    2011-12-01

    Detonation of a three-dimensional reactive nonisotropic molecular crystal is modeled using molecular dynamics simulations. The detonation process is initiated by an impulse, followed by the creation of a stable fast reactive shock wave. The terminal shock velocity is independent of the initiation conditions. Further analysis shows supersonic propagation decoupled from the dynamics of the decomposed material left behind the shock front. The dependence of the shock velocity on crystal nonlinear compressibility resembles solitary behavior. These properties categorize the phenomena as a weak detonation. The dependence of the detonation wave on microscopic potential parameters was investigated. An increase in detonation velocity with the reaction exothermicity reaching a saturation value is observed. In all other respects the model crystal exhibits typical properties of a molecular crystal. PMID:22304055

  1. Detonation wave compression in gas turbines

    Science.gov (United States)

    Wortman, A.

    1986-01-01

    A study was made of the concept of augmenting the performance of low pressure ratio gas turbines by detonation wave compression of part of the flow. The concept exploits the constant volume heat release of detonation waves to increase the efficiency of the Brayton cycle. In the models studied, a fraction of the compressor output was channeled into detonation ducts where it was processed by transient transverse detonation waves. Gas dynamic studies determined the maximum cycling frequency of detonation ducts, proved that upstream propagation of pressure pulses represented no problems and determined the variations of detonation duct output with time. Mixing and wave compression were used to recombine the combustor and detonation duct flows and a concept for a spiral collector to further smooth the pressure and temperature pulses was presented as an optional component. The best performance was obtained with a single firing of the ducts so that the flow could be re-established before the next detonation was initiated. At the optimum conditions of maximum frequency of the detonation ducts, the gas turbine efficiency was found to be 45 percent while that of a corresponding pressure ratio 5 conventional gas turbine was only 26%. Comparable improvements in specific fuel consumption data were found for gas turbines operating as jet engines, turbofans, and shaft output machines. Direct use of the detonation duct output for jet propulsion proved unsatisfactory. Careful analysis of the models of the fluid flow phenomena led to the conclusion that even more elaborate calculations would not diminish the uncertainties in the analysis of the system. Feasibility of the concept to work as an engine now requires validation in an engineering laboratory experiment.

  2. Prognostic parameters in benign astrocytomas

    DEFF Research Database (Denmark)

    Westergaard, L; Gjerris, F; Klinken, L

    1993-01-01

    To elucidate the prognosis of different types of benign astrocytomas and to ascertain whether patients with partially resected benign astrocytomas, or any subtype of these, would benefit from postoperative radiotherapy, we studied retrospectively material comprising 300 patients with benign...... astrocytomas treated in the period 1956 to 1991. The pilocytic type of astrocytoma was found to have an outstandingly good prognosis and should be regarded as a distinct nosological entity. For the non-pilocytic supratentorial astrocytomas, a multivariate regression analysis showed that age, tumour site...... time of patients with non-pilocytic supratentorial benign astrocytomas. The study emphasizes the necessity of a prospective combined multicenter analysis of the effect of radiation on benign astrocytomas....

  3. [Benign endobronchial tumors].

    Science.gov (United States)

    Nikhtianov, Kh

    1980-01-01

    Endobronchial localizations of benign neoplasms are met with in 24.5 per cent of the cases. Right lung localizations are more frequent. More than half of them are broadly based (57.5 per cent). In most of the cases it is a matter of nonepithelial tumours of which a greater intensity is displayed by hamartomas /7/, vascular /4/ and neurogenic /3/ neoformations. The size of endobronchial tumours varies from 1 to 10 cm. Cases measuring 1-3 cm are the most numerous. Those of the "iceberg" type appear to be larger. The size per se has a relative importance for the clinical picture. Endobronchial tumours exhibit a clear cut clinical picture, and run a clinical course in three stages, determined by the degree of bronchial obturation and longstanding of the condition. The most common symptoms are coughing /80.7 per cent/, expectoration /50.0 per cent/, rales /57.6 per cent/, dullness /38.4 per cent/ and lacking respiration /38.4 per cent/. The nosological entity by itself is less conclusive for the clinical course. The X-ray data have orientation and by no means decisive significance for the diagnosis. The "crab pincers" sign in the bronchial lumen during bronchography has a definite importance. Bronchoscopy in conjunction with biopsy is a dependable method of preoperative diagnosing. It contributes greatly to the nosological diagnosis. Even nowadays, the diagnosis of endobronchial tumours is difficult. A rather exact diagnosis can be made intraoperatively, whereas the most accurate diagnosis is established only after histological study. The treatment of endobronchial benign neoplasms is operative. The number of medium /lobectomies/ and extensive /pulmonectomies/ pulmonary resections is considerable. In case of early diagnosis and intervention, sparing resection is the naturally indicated size of operation - mainly resection and plasty of the bronchi without lobectomy. The advantages of circular resection are substantial. Reconstructive operations of "clarinet" and

  4. 19th Biannual Symposium of the German Aerospace Aerodynamics Association (STAB) and the German Society for Aeronautics and Astronautics (DGLR)

    CERN Document Server

    Heller, Gerd; Krämer, Ewald; Wagner, Claus; Breitsamter, Christian

    2016-01-01

    This book presents contributions to the 19th biannual symposium of the German Aerospace Aerodynamics Association (STAB) and the German Society for Aeronautics and Astronautics (DGLR). The individual chapters reflect ongoing research conducted by the STAB members in the field of numerical and experimental fluid mechanics and aerodynamics, mainly for (but not limited to) aerospace applications, and cover both nationally and EC-funded projects. Special emphasis is given to collaborative research projects conducted by German scientists and engineers from universities, research-establishments and industries. By addressing a number of cutting-edge applications, together with the relevant physical and mathematics fundamentals, the book provides readers with a comprehensive overview of the current research work in the field. Though the book’s primary emphasis is on the aerospace context, it also addresses further important applications, e.g. in ground transportation and energy. .

  5. Suicide by self-inflicted stab wound to the heart: a rare case of suicide from Nepal

    Directory of Open Access Journals (Sweden)

    S Jha

    2015-07-01

    Full Text Available Suicide, or the deliberate act of killing oneself, accounts for a substantial number of unnatural deaths each year in many countries. Though death by self-stabbing is quite uncommon, the left part of the chest represents one of the elected sites of self-inflicted wounds because of the knowledge of the situation of the heart and that the injuries to the heart are severe. We present a case of suicidal stab to the left thoracic region involving the heart.DOI: http://dx.doi.org/10.3126/jcmsn.v10i2.12952 Journal of College of Medical Sciences-Nepal, 2014, Vol.10(2; 33-35

  6. The direct cost of traumatic secretion transfer in hermaphroditic land snails: individuals stabbed with a love dart decrease lifetime fecundity

    OpenAIRE

    Kimura, Kazuki; Chiba, Satoshi

    2015-01-01

    Several taxa of simultaneously hermaphroditic land snails exhibit a conspicuous mating behaviour, the so-called shooting of love darts. During mating, such land snail species transfer a specific secretion by stabbing a mating partner's body with the love dart. It has been shown that sperm donors benefit from this traumatic secretion transfer, because the secretions manipulate the physiology of a sperm recipient and increase the donors' fertilization success. However, it is unclear whether rec...

  7. Effect of Detonation through a Turbine Stage

    Science.gov (United States)

    Ellis, Matthew T.

    2004-01-01

    Pulse detonation engines (PDE) have been investigated as a more efficient means of propulsion due to its constant volume combustion rather than the more often used constant pressure combustion of other propulsion systems. It has been proposed that a hybrid PDE-gas turbine engine would be a feasible means of improving the efficiency of the typical constant pressure combustion gas turbine cycle. In this proposed system, multiple pulse detonation tubes would replace the conventional combustor. Also, some of the compressor stages may be removed due to the pressure rise gained across the detonation wave. The benefits of higher thermal efficiency and reduced compressor size may come at a cost. The first question that arises is the unsteadiness in the flow created by the pulse detonation tubes. A constant pressure combustor has the advantage of supplying a steady and large mass flow rate. The use of the pulse detonation tubes will create an unsteady mass flow which will have currently unknown effects on the turbine located downstream of the combustor. Using multiple pulse detonation tubes will hopefully improve the unsteadiness. The interaction between the turbine and the shock waves exiting the tubes will also have an unknown effect. Noise levels are also a concern with this hybrid system. These unknown effects are being investigated using TURBO, an unsteady turbomachinery flow simulation code developed at Mississippi State University. A baseline case corresponding to a system using a constant pressure combustor with the same mass flow rate achieved with the pulse detonation hybrid system will be investigated first.

  8. Explosion and detonation characteristics of dimethyl ether.

    Science.gov (United States)

    Mogi, Toshio; Horiguchi, Sadashige

    2009-05-15

    In this study, the explosion and detonation characteristics of dimethyl ether (DME) were experimentally investigated. A spherical pressure vessel with an internal volume of 180L was used as the explosion vessel. Therefore, tubes 10m in length with internal diameters of 25mm and 50mm were used as detonation tubes. In addition, we compared the characteristics of DME with those of propane since DME is considered as a substitute fuel for liquid petroleum gas (LPG). At room temperature and atmospheric pressure, the maximum explosive pressure increased tenfold. The explosion index (K(G) values), an indicator of the intensity of an explosion, was larger than that of propane, indicating that the explosion was intense. No experimental study has been conducted on the detonation behavior of DME so far, but this research confirmed a transition to detonation. The detonation characteristics were similar to the characteristics of the Chapman-Jouguet detonation, and the concentration range for detonation was from 5.5% to 9.0%. PMID:18774641

  9. Reinforced concrete wall under hydrogen detonation

    International Nuclear Information System (INIS)

    The structural integrity of a reinforced concrete wall in the BWR reactor building under hydrogen detonation conditions has been analysed. Of particular interest is whether the containment integrity can be jeopardised by an external hydrogen detonation. The load carrying capacity of a reinforced concrete wall was studied. The detonation pressure loads were estimated with computerised hand calculations assuming a direct initiation of detonation and applying the strong explosion theory. The results can be considered as rough and conservative estimates for the first shock pressure impact induced by a reflecting detonation wave. Structural integrity may be endangered due to slow pressurisation or dynamic impulse loads associated with local detonations. The static pressure following the passage of a shock front may be relatively high, thus this static or slowly decreasing pressure after a detonation may damage the structure severely. The mitigating effects of the opening of a door on pressure history and structural response were also studied. The non-linear behaviour of the wall was studied under detonations corresponding a detonable hydrogen mass of 0.5 kg and 1.428 kg. Non-linear finite element analyses of the reinforced concrete structure were carried out by the ABAQUS/Explicit program. The reinforcement and its non-linear material behaviour and the tensile cracking of concrete were modelled. Reinforcement was defined as layers of uniformly spaced reinforcing bars in shell elements. In these studies the surrounding structures of the non-linearly modelled reinforced concrete wall were modelled using idealised boundary conditions. Especially concrete cracking and yielding of the reinforcement was monitored during the numerical simulation. (au)

  10. Simplified calculation of detonation induced impulse

    International Nuclear Information System (INIS)

    Simplified methods of estimating the impulse generated by detonations propagating through gaseous fuel-oxidizer mixtures are developed. First the ground and dynamic impulse are defined. Self similar solutions are used to derive expressions for the ground and dynamic impulse of detonations confined clouds with plane, cylindrical, and spherical symmetry in terms of universal impulse functions which are independent of the detonation properties. A similar analysis is developed for clouds bounded by an inert gas which results in side relief. In this case the results are found to be in good agreement with experiment and with hydrocode calculations

  11. VLW equation of state of detonation products

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on the virial theory, we proposed VLW equation of state of detonation products (VLW EOS). Its basic theory and applications were described. The distinct features of the VLW EOS were:First, the detonation performance of the new high energy density materials could be predicted more reliably. Second, it had extensive application. The detonation parameters of both the condensed high energy density materials and the gaseous fuel air explosives could be calculated. Moreover, combustion performance of propellants could also be precisely calculated. The calculation results were satisfactory.

  12. Cellular Cell Bifurcation of Cylindrical Detonations

    Institute of Scientific and Technical Information of China (English)

    HAN Gui-Lai; JIANG Zong-Lin; WANG Chun; ZHANG Fan

    2008-01-01

    Cellular cell pattern evolution of cylindrically-diverging detonations is numerically simulated successfully by solving two-dimensional Euler equations implemented with an improved two-step chemical kinetic model. From the simulation, three cell bifurcation modes are observed during the evolution and referred to as concave front focusing, kinked and wrinkled wave front instability, and self-merging of cellular cells. Numerical research demonstrates that the wave front expansion resulted from detonation front diverging plays a major role in the cellular cell bifurcation, which can disturb the nonlinearly self-sustained mechanism of detonations and finally lead to cell bifurcations.

  13. Qualitative and quantitative analysis of detonation products

    International Nuclear Information System (INIS)

    Different sampling and different injection method were used during analyzing unknown detonation products in a obturator. The sample analyzed by gas chromatography and gas chromatography/mass spectrum. Qualitative analysis was used with CO, NO, C2H2, C6H6 and so on, qualitative analysis was used with C3H5N, C10H10, C8H8N2 and so on. The method used in the article is feasible. The results show that the component of detonation in the study is negative oxygen balance, there were many pollutants in the detonation products. (authors)

  14. Critical Initiation Conditions for Gaseous Diverging Spherical Detonations

    OpenAIRE

    Desbordes, D.

    1995-01-01

    The diverging spherical detonation wave in gaseous explosives is obtained either with a point source of explosion of energy E or through the transmission of a plane detonation from a cylindrical tube of diameter d into a large volume. The mechanism of detonation initiation in both cases is based on the shock to detonation transition. The experimental critical conditions lead to an initiation criterion for detonation resulting from the competition between the expansion behind the leading shock...

  15. Detonation and transition to detonation in partially water-filled pipes

    OpenAIRE

    Bitter, Neal P.; Shepherd, Joseph E.

    2012-01-01

    Detonations and deflagration-to-detonation transition (DDT) are experimentally studied in horizontal pipes which are partially filled with water. The gas layer above the water is stoichiometric hydrogen-oxygen at 1 bar. For detonation cases, ignition and transition occur outside of the water-filled section. For DDT cases, ignition and transition occur over the surface of the water. Pressure and hoop strain are measured incrementally along the pipe, with pressure transducers located both above...

  16. Double-detonation sub-Chandrasekhar supernovae: can minimum helium shell masses detonate the core?

    OpenAIRE

    Fink, M.; Roepke, F. K.; Hillebrandt, W.; Seitenzahl, I. R.; Sim, S. A.; Kromer, M.

    2010-01-01

    The explosion of sub-Chandrasekhar mass white dwarfs via the double detonation scenario is a potential explanation for type Ia supernovae. In this scenario, a surface detonation in a helium layer initiates a detonation in the underlying carbon/oxygen core leading to an explosion. For a given core mass, a lower bound has been determined on the mass of the helium shell required for dynamical burning during a helium flash, which is a necessary prerequisite for detonation. For a range of core and...

  17. Benign Myoclonus of Early Infancy

    OpenAIRE

    J Gordon Millichap

    2009-01-01

    To redefine benign myoclonus of early infancy (BMEI), clinical and neurophysiologic features in 102 infants (60 male) with brief paroxysmal abnormal movements and normal neurologic and psychomotor development were studied at one center in Argentina and two in Italy.

  18. Confined detonations with cylindrical and spherical symmetry

    International Nuclear Information System (INIS)

    An imploding spherical or cylindrical detonation, starting in the interface of the detonantion with an external inert media, used as a reflector, creates on it a strong shock wave moving outward from the interface. An initially weak shock wave appears in the detonated media that travels toward the center, and it could reach the detonation wave, enforcing it in its process of implosion. To describe the fluid field, the Euler s equations are solved by means of expansions valid for the early stages of the process. Isentropic of the type P/pγ-K for the detonated and compressed inert media are used. For liquid or solid reflectors a more appropriate equation is used. (Author) 8 refs

  19. Parametric study of double cellular detonation structure

    Science.gov (United States)

    Khasainov, B.; Virot, F.; Presles, H.-N.; Desbordes, D.

    2013-05-01

    A parametric numerical study is performed of a detonation cellular structure in a model gaseous explosive mixture whose decomposition occurs in two successive exothermic reaction steps with markedly different characteristic times. Kinetic and energetic parameters of both reactions are varied in a wide range in the case of one-dimensional steady and two-dimensional (2D) quasi-steady self-supported detonations. The range of governing parameters of both exothermic steps is defined where a "marked" double cellular structure exists. It is shown that the two-level cellular structure is completely governed by the kinetic parameters and the local overdrive ratio of the detonation front propagating inside large cells. Furthermore, since it is quite cumbersome to use detailed chemical kinetics in unsteady 2D case, the proposed work should help to identify the mixtures and the domain of their equivalence ratio where double detonation structure could be observed.

  20. Equation of state for detonation product gases

    International Nuclear Information System (INIS)

    Based on the empirical linear relationship between detonation velocity and loading density, an approximate description for the Chapman-Jouguet (CJ) state for detonation product gases has been presented. Assuming that the Grüneisen parameter is a function only of volume, we obtained the Grüneisen parameter along CJ states. Thermodynamic identity between the Grüneisen parameter and another non-dimensional material parameter R used in the Rice-Walsh type equation of state introduced by Wu and Jing can be used to derive the enthalpy-pressure-volume equation of state for detonation gases. Behavior of this parameter R as a function of pressure is calculated and revealed that their change with pressure is very gradual and seems to approach a finite value with decreasing pressure. Release isentropes from CJ states of several initial density detonation of PETN is shown.

  1. Detonation wave augmentation of gas turbines

    Science.gov (United States)

    Wortman, A.

    1984-01-01

    The results of a feasibility study that examined the effects of using detonation waves to augment the performance of gas turbines are reported. The central ideas were to reduce compressor requirements and to maintain high performance in jet engines. Gasdynamic equations were used to model the flows associated with shock waves generated by the detonation of fuel in detonator tubes. Shock wave attenuation to the level of Mach waves was found possible, thus eliminating interference with the compressor and the necessity of valves and seals. A preliminary parametric study of the performance of a compressor working at a 4:1 ratio in a conceptual design of a detonation wave augmented jet engine in subsonic flight indicated a clear superiority over conventional designs in terms of fuel efficiency and thrust.

  2. Radiation treatment of benign diseases

    International Nuclear Information System (INIS)

    The report deals with an estimation of the volume of radiation treatment of benign diseases in Norway and gives a survey of the subjective opinion of patients regarding the result of the treatment. Reported subjective recovery after radiation treatment seems to be at the same level as recovery without treatment. For an indication of the objective effect of radiation treatment of benign diseases, the subjective effect of this treatment has to be compared with objective findings

  3. Initiation and Detonation Physics on Millimeter Scales

    Energy Technology Data Exchange (ETDEWEB)

    Philllips, D F; Benterou, J J; May, C A

    2012-03-20

    The LLNL Detonation Science Project has a major interest in understanding the physics of detonation on a millimeter scale. This report summarizes the rate stick experiment results of two high explosives. The GO/NO-GO threshold between varying diameters of ultra-fine TATB (ufTATB) and LX-16 were recorded on an electronic streak camera and analyzed. This report summarizes the failure diameters of rate sticks for ufTATB and LX-16. Failure diameter for the ufTATB explosive, with densities at 1.80 g/cc, begin at 2.34 mm (not maintaining detonation velocity over the entire length of the rate stick). ufTATB rate sticks at the larger 3.18 mm diameter maintain a constant detonation velocity over the complete length. The PETN based and LLNL developed explosive, LX-16, with densities at 1.7 g/cc, shows detonation failure between 0.318 mm and 0.365 mm. Additional tests would be required to narrow this failure diameter further. Many of the tested rate sticks were machined using a femtosecond laser focused into a firing tank - in case of accidental detonation.

  4. Prechamber initiation of detonation in gaseous mixtures

    Science.gov (United States)

    Bivol, G. Yu; Golovastov, S. V.; Golub, V. V.

    2015-11-01

    A process of deflagration-to-detonation transition in propane-butane-oxygen and acetylene-oxygen mixtures, in an open channel with a circular cross section with a diameter of 3 mm, was investigated experimentally. Detonation initiation was carried out by burning the mixture in the prechamber connected to the channel. The prechamber was considered as an extended source for the initiation of the detonation of a finite volume. To measure the velocity of a flame front, photodiodes, installed along the axis of the channel, were used. To determine the boundary conditions at the entrance to the channel, a piezoelectric pressure transducer was used. The influence of the dimensions of the prechamber, equivalence ratio and fuel on the pressure profile, and evolution of the flame front along the axis of the channel are presented. It was shown that, the dynamics of the flame front and shock waves in the channel can occur in different scenarios depending on the geometry of the prechamber and equivalence ratio. Two limit effects of the prechamber detonation initiation in the channel have been analyzed. The pre-detonation distances and the minimal energy of direct initiation of the detonation were determined.

  5. Qualitative and Asymptotic Theory of Detonations

    KAUST Repository

    Faria, Luiz

    2014-11-09

    Shock waves in reactive media possess very rich dynamics: from formation of cells in multiple dimensions to oscillating shock fronts in one-dimension. Because of the extreme complexity of the equations of combustion theory, most of the current understanding of unstable detonation waves relies on extensive numerical simulations of the reactive compressible Euler/Navier-Stokes equations. Attempts at a simplified theory have been made in the past, most of which are very successful in describing steady detonation waves. In this work we focus on obtaining simplified theories capable of capturing not only the steady, but also the unsteady behavior of detonation waves. The first part of this thesis is focused on qualitative theories of detonation, where ad hoc models are proposed and analyzed. We show that equations as simple as a forced Burgers equation can capture most of the complex phenomena observed in detonations. In the second part of this thesis we focus on rational theories, and derive a weakly nonlinear model of multi-dimensional detonations. We also show, by analysis and numerical simulations, that the asymptotic equations provide good quantitative predictions.

  6. Effect of Resolution on Propagating Detonation Wave

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-10

    Simulations of the cylinder test are used to illustrate the effect of mesh resolution on a propagating detonation wave. For this study we use the xRage code with the SURF burn model for PBX 9501. The adaptive mesh capability of xRage is used to vary the resolution of the reaction zone. We focus on two key properties: the detonation speed and the cylinder wall velocity. The latter is related to the release isentrope behind the detonation wave. As the reaction zone is refined (2 to 15 cells for cell size of 62 to 8μm), both the detonation speed and final wall velocity change by a small amount; less than 1 per cent. The detonation speed decreases with coarser resolution. Even when the reaction zone is grossly under-resolved (cell size twice the reaction-zone width of the burn model) the wall velocity is within a per cent and the detonation speed is low by only 2 per cent.

  7. Radical pancreaticoduodenectomy for benign disease.

    LENUS (Irish Health Repository)

    Kavanagh, D O

    2008-01-01

    Whipple\\'s procedure is the treatment of choice for pancreatic and periampullary malignancies. Preoperative histological confirmation of malignancy is frequently unavailable and some patients will subsequently be found to have benign disease. Here, we review our experience with Whipple\\'s procedure for patients ultimately proven to have benign disease. The medical records of all patients who underwent Whipple\\'s procedure during a 15-year period (1987-2002) were reviewed; 112 patients underwent the procedure for suspected malignancy. In eight cases, the final histology was benign (7.1%). One additional patient was known to have benign disease at resection. The mean age was 50 years (range: 30-75). The major presenting features included jaundice (five), pain (two), gastric outlet obstruction (one), and recurrent gastrointestinal haemorrhage (one). Investigations included ultrasound (eight), computerised tomography (eight), endoscopic retrograde cholangiopancreatography (seven; of these, four patients had a stent inserted and three patients had sampling for cytology), and endoscopic ultrasound (two). The pathological diagnosis included benign biliary stricture (two), chronic pancreatitis (two), choledochal cyst (one), inflammatory pseudotumour (one), cystic duodenal wall dysplasia (one), duodenal angiodysplasia (one), and granular cell neoplasm (one). There was no operative mortality. Morbidity included intra-abdominal collection (one), anastomotic leak (one), liver abscess (one), and myocardial infarction (one). All patients remain alive and well at mean follow-up of 41 months. Despite recent advances in diagnostic imaging, 8% of the patients undergoing Whipple\\'s procedure had benign disease. A range of unusual pathological entities can mimic malignancy. Accurate preoperative histological diagnosis may have allowed a less radical operation to be performed. Endoscopic ultrasound-guided fine needle aspirate (EUS-FNA) may reduce the need for Whipple\\'s operation

  8. Radical Pancreaticoduodenectomy for Benign Disease

    Directory of Open Access Journals (Sweden)

    D. O. Kavanagh

    2008-01-01

    Full Text Available Whipple's procedure is the treatment of choice for pancreatic and periampullary malignancies. Preoperative histological confirmation of malignancy is frequently unavailable and some patients will subsequently be found to have benign disease. Here, we review our experience with Whipple's procedure for patients ultimately proven to have benign disease. The medical records of all patients who underwent Whipple's procedure during a 15-year period (1987–2002 were reviewed; 112 patients underwent the procedure for suspected malignancy. In eight cases, the final histology was benign (7.1%. One additional patient was known to have benign disease at resection. The mean age was 50 years (range: 30–75. The major presenting features included jaundice (five, pain (two, gastric outlet obstruction (one, and recurrent gastrointestinal haemorrhage (one. Investigations included ultrasound (eight, computerised tomography (eight, endoscopic retrograde cholangiopancreatography (seven; of these, four patients had a stent inserted and three patients had sampling for cytology, and endoscopic ultrasound (two. The pathological diagnosis included benign biliary stricture (two, chronic pancreatitis (two, choledochal cyst (one, inflammatory pseudotumour (one, cystic duodenal wall dysplasia (one, duodenal angiodysplasia (one, and granular cell neoplasm (one. There was no operative mortality. Morbidity included intra-abdominal collection (one, anastomotic leak (one, liver abscess (one, and myocardial infarction (one. All patients remain alive and well at mean follow-up of 41 months. Despite recent advances in diagnostic imaging, 8% of the patients undergoing Whipple'’s procedure had benign disease. A range of unusual pathological entities can mimic malignancy. Accurate preoperative histological diagnosis may have allowed a less radical operation to be performed. Endoscopic ultrasound–guided fine needle aspirate (EUS-FNA may reduce the need for Whipple's operation in

  9. Benign fibrous histiocytoma of the lumbar vertebrae

    Energy Technology Data Exchange (ETDEWEB)

    Demiralp, Bahtiyar; Oguz, Erbil; Sehirlioglu, Ali [Gulhane Military Medical Academy, Department of Orthopedics and Traumatology, Ankara (Turkey); Kose, Ozkan [Diyarbakir Education and Research Hospital, Department of Orthopedics and Traumatology, Diyarbakir (Turkey); Ataslar Serhat Evleri, Diclekent Bulvari, Diyarbakir (Turkey); Sanal, Tuba [Gulhane Military Medical Academy, Department of Radiology, Ankara (Turkey); Ozcan, Ayhan [Gulhane Military Medical Academy, Department of Pathology, Ankara (Turkey)

    2009-02-15

    Benign fibrous histiocytoma is an extremely rare spinal tumor with ten reported cases in the literature. Benign fibrous histiocytoma constitutes a diagnostic challenge because it shares common clinical symptoms, radiological characteristics, and histological features with other benign lesions involving the spine. We present a case of benign fibrous histiocytoma of the lumbar spine and discuss its differential diagnosis and management. (orig.)

  10. Benign mixed tumor of the lacrimal sac

    Directory of Open Access Journals (Sweden)

    Jong-Suk Lee

    2015-01-01

    Full Text Available Neoplasms of the lacrimal drainage system are uncommon, but potentially life-threatening and are often difficult to diagnose. Among primary lacrimal sac tumors, benign mixed tumors are extremely rare. Histologically, benign mixed tumors have been classified as a type of benign epithelial tumor. Here we report a case of benign mixed tumor of the lacrimal sac.

  11. Detonating Cord for Flux Compression Generation using Electrical Detonator No. 33

    Directory of Open Access Journals (Sweden)

    P B. Wagh

    2011-01-01

    Full Text Available The paper highlights the use of electrical detonators for magnetic flux compression generator applications which requires synchronisation of two events with precise time delay of tens of ms and jitter within a few ms. These requirements are generally achieved by exploding bridge wire type detonators which are difficult to develop and are not commercially available. A technique has been developed using commercially available electrical detonator no. 33 to synchronise between peak of seed current in stator coil and detonation of explosive charge in armature. In present experiments, electrical signal generated by self-shorting pin due to bursting of electrical detonator has been used to trigger the capacitor discharge and the detonating cord of known length has been used to incorporate predetermined delay to synchronise the events. It has been demonstrated that using electrical detonator and known length of detonating cord, the two events can be synchronised with predetermined delay between 31 and 251 ms with variation of ± 0.5ms. The technique developed is suitable for defence applications like generation of high power microwaves using explosive driven magnetic flux compression generators.Defence Science Journal, 2011, 61(1, pp.19-24, DOI:http://dx.doi.org/10.14429/dsj.61.30

  12. One Year Term Review as a Participating Guest in the Detonator and Detonation Physics Group

    Energy Technology Data Exchange (ETDEWEB)

    Lefrancois, A; Roeske, F; Tran, T; Lee, R S

    2006-02-06

    The one year stay was possible after a long administrative process, because of the fact that this was the first participating guest of B division as a foreign national in HEAF (High Explosives Application Facility) with the Detonator/Detonation Physics Group.

  13. Stab Incision Glaucoma Surgery: A Modified Guarded Filtration Procedure for Primary Open Angle Glaucoma

    Science.gov (United States)

    Jacob, Soosan; Figus, Michele; Ashok Kumar, Dhivya; Areeckal Incy, Saijimol

    2016-01-01

    Purpose. To describe a modified guarded filtration surgery, stab incision glaucoma surgery (SIGS), for primary open angle glaucoma (POAG). Methods. This prospective, interventional case series included patients with POAG (IOP ≥21 mmHg with glaucomatous visual field defects). After sliding superior conjunctiva down over limbus, 2.8 mm bevel-up keratome was used to create conjunctival entry and superficial corneoscleral tunnel in a single step starting 1.5 mm behind limbus. Lamellar corneoscleral tunnel was carefully dissected 0.5–1 mm into cornea and anterior chamber (AC) was entered. Kelly Descemet's punch (1 mm) was slid along the tunnel into AC to punch internal lip of the tunnel, thereby compromising it. Patency of ostium was assessed by injecting fluid in AC and visualizing leakage from tunnel. Conjunctival incision alone was sutured. Results. Mean preoperative IOP was 27.41 ± 5.54 mmHg and mean postoperative IOP was 16.47 ± 4.81 mmHg (n = 17). Mean reduction in IOP was 38.81 ± 16.55%. There was significant reduction of IOP (p < 0.000). 64.7% had IOP at final follow-up of <18 mmHg without medication and 82.35% had IOP <18 mmHg with ≤2 medications. No sight threatening complications were encountered. Conclusion. Satisfactory IOP control was noted after SIGS in interim follow-up (14.18 ± 1.88 months). PMID:27144015

  14. Gaseous detonation synthesis and characterization of nano-oxide

    Science.gov (United States)

    Yan, Honghao; Wu, Linsong; Li, Xiaojie; Wang, Xiaohong

    2015-07-01

    Gaseous detonation is a new method of heating the precursor of nanomaterials into gas, and integrating it with combustible gas as mixture to be detonated for the synthesis of nanomaterials. In this paper, the mixed gas of oxygen and hydrogen is used as the source for detonation, to synthesize nano TiO2, nano SiO2 and nano SnO2 through gaseous detonation method, characterization and analysis of the products, it was found that the products from gaseous detonation method were of high purity, good dispersion, smaller particle size and even distribution. It also shows that for the synthesis of nano-oxides, gaseous detonation is universal.

  15. Cholesterol and benign prostate disease.

    Science.gov (United States)

    Freeman, Michael R; Solomon, Keith R

    2011-01-01

    The origins of benign prostatic diseases, such as benign prostatic hyperplasia (BPH) and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), are poorly understood. Patients suffering from benign prostatic symptoms report a substantially reduced quality of life, and the relationship between benign prostate conditions and prostate cancer is uncertain. Epidemiologic data for BPH and CP/CPPS are limited, however an apparent association between BPH symptoms and cardiovascular disease (CVD) has been consistently reported. The prostate synthesizes and stores large amounts of cholesterol and prostate tissues may be particularly sensitive to perturbations in cholesterol metabolism. Hypercholesterolemia, a major risk factor for CVD, is also a risk factor for BPH. Animal model and clinical trial findings suggest that agents that inhibit cholesterol absorption from the intestine, such as the class of compounds known as polyene macrolides, can reduce prostate gland size and improve lower urinary tract symptoms (LUTS). Observational studies indicate that cholesterol-lowering drugs reduce the risk of aggressive prostate cancer, while prostate cancer cell growth and survival pathways depend in part on cholesterol-sensitive biochemical mechanisms. Here we review the evidence that cholesterol metabolism plays a role in the incidence of benign prostate disease and we highlight possible therapeutic approaches based on this concept. PMID:21862201

  16. Flaw detecting method for welded portion between lower end plate and stab tube of reactor pressure vessel and liquid medium-filling device used for the method

    International Nuclear Information System (INIS)

    The present invention provides a method of reliably performing an ultrasonic flaw detecting test for a welded portion between a lower end plate and a stab tube of a reactor pressure vessel. Namely, a liquid medium is filled into a space formed between the outer circumference of a housing of a driving device, and an inner surface of a driving device-insertion hole and the stab tube. Ultrasonic waves are appropriately transferred to the welded portion by means of the liquid medium. Accordingly, the ultrasonic test can reliably be performed for the welded portion between the lower end plate and the stab tube. In addition, the housing of the driving device is coated at a portion where it is situated to the outer side of the main body of the pressure vessel. The liquid medium is continuously supplied from a medium supply device into the inside of the main body of the filling device. The liquid medium is filled into the space formed by the outer circumference of the housing of the driving device, and the inner surface of the insertion hole of the driving device and the stab tube. Accordingly, ultrasonic test can reliably performed for the welded portion between the lower end plate and the stab tube. (I.S.)

  17. Review on Recent Advances in Pulse Detonation Engines

    Directory of Open Access Journals (Sweden)

    K. M. Pandey

    2016-01-01

    Full Text Available Pulse detonation engines (PDEs are new exciting propulsion technologies for future propulsion applications. The operating cycles of PDE consist of fuel-air mixture, combustion, blowdown, and purging. The combustion process in pulse detonation engine is the most important phenomenon as it produces reliable and repeatable detonation waves. The detonation wave initiation in detonation tube in practical system is a combination of multistage combustion phenomena. Detonation combustion causes rapid burning of fuel-air mixture, which is a thousand times faster than deflagration mode of combustion process. PDE utilizes repetitive detonation wave to produce propulsion thrust. In the present paper, detailed review of various experimental studies and computational analysis addressing the detonation mode of combustion in pulse detonation engines are discussed. The effect of different parameters on the improvement of propulsion performance of pulse detonation engine has been presented in detail in this research paper. It is observed that the design of detonation wave flow path in detonation tube, ejectors at exit section of detonation tube, and operating parameters such as Mach numbers are mainly responsible for improving the propulsion performance of PDE. In the present review work, further scope of research in this area has also been suggested.

  18. Design of environmentally benign processes

    DEFF Research Database (Denmark)

    Hostrup, Martin; Harper, Peter Mathias; Gani, Rafiqul

    1999-01-01

    This paper presents a hybrid method for design of environmentally benign processes. The hybrid method integrates mathematical modelling with heuristic approaches to solving the optimisation problems related to separation process synthesis and solvent design and selection. A structured method of...... solution, which employs thermodynamic insights to reduce the complexity and size of the mathematical problem by eliminating redundant alternatives, has been developed for the hybrid method. Separation process synthesis and design problems related to the removal of a chemical species from process streams...... mixture and the second example involves the determination of environmentally benign substitute solvents for removal of a chemical species from wastewater. (C) 1999 Elsevier Science Ltd. All rights reserved....

  19. Detonation diffraction from an annular channel

    Science.gov (United States)

    Meredith, James; Ng, Hoi Dick; Lee, John H. S.

    2010-12-01

    In this study, gaseous detonation diffraction from an annular channel was investigated with a streak camera and the critical pressure for transmission of the detonation wave was obtained. The annular channel was used to approximate an infinite slot resulting in cylindrically expanding detonation waves. Two mixtures, stoichiometric acetylene-oxygen and stoichiometric acetylene-oxygen with 70% Ar dilution, were tested in a 4.3 and 14.3 mm channel width ( W). The undiluted and diluted mixtures were found to have values of the critical channel width over the cell size around 3 and 12 respectively. Comparing these results to values of the critical diameter ( d c ), in which a spherical detonation occurs, a value of critical d c / W c near 2 is observed for the highly diluted mixture. This value corresponds to the geometrical factor of the curvature term between a spherical and cylindrical diverging wave. Hence, the result is in support of Lee's proposed mechanism [Lee in Dynamics of Exothermicity, pp. 321, Gordon and Breach, Amsterdam, 1996] for failure due to diffraction based on curvature in stable mixtures such as those highly argon diluted with very regular detonation cellular patterns.

  20. Is "Benign Childhood Epilepsy with Centrotemporal Spikes” Always Benign?

    Directory of Open Access Journals (Sweden)

    Muhammad SAEED

    2014-07-01

    Full Text Available How to Cite This Article: Saeed M, Azam M, Shabbir N, Qamar ShA. Is "Benign Childhood Epilepsy with Centrotemporal Spikes" Always Benign? Iran J Child Neurol. 2014 Summer;8(3: 39-45.AbstractObjectiveTo determine the prevalence of associated behavioral problems and prognosis with Benign Childhood Epilepsy with CentroTemporal Spikes (BCECTS.Descriptive, Cross Sectional study that was conducted from October 2009 to April 2013 in the Department of Pediatric Neurology, the Children’s Hospital Taif, KSA.Material & MethodsThis study was conducted after approval from the Ethics Committee of the Children’s Hospital Taif, Saudi Arabia. Thirty-two patients from the age of 3 to 10 years old were recruited from the pediatric neurology clinic over a period of 4 years. All the patients were selected based on history, EEGs, and neuropsychological and neurological examinations.EEGs were performed for all the patients while in awake and sleep states. Those who had centrotemporal discharges were included in the study. All the patients also underwent a brain MRI. Only two patients had mild cortical atrophy but developmentally they were normal.ResultsIn our study, prevalence of BRE is 32/430 (7.44%. Among the 32 cases, 24 were male and eight were female. Six cases out of 32 indicated a family history of BRE. Twenty-eight cases had unilateral right sided centrotemporal discharges and four had bilateral discharges.ConclusionIt is possible that for BECTS, a high number of seizures might play an important role in the development of mild cognitive impairment and/or behavior disturbances.ReferencesBradley WG, Daroff RB, Fenichel JM, Jahrovic J. Neurology of clinical practice. 5th Ed. 2009: pp. 1953-1990.Berg AT, Berkovic SF, Brodie MJ, Buchhalter J, Cross H, Van Emde Boas M, et al: Revised terminology and concepts for organization of seizures and epilepsies: Report of the ILAE Commission on Classification and Terminology, 2005–2009. Epilepsia. 2010

  1. Detailed structure of spinning detonation in a circular tube

    Energy Technology Data Exchange (ETDEWEB)

    Tsuboi, N. [Space Transportation Engineering Department, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510 (Japan); Eto, K.; Hayashi, A.K. [Department of Mechanical Engineering, Aoyama Gakuin University, Fuchinobe 5-10-1, Sagamihara, Kanagawa 229-8558 (Japan)

    2007-04-15

    A single spinning detonation wave propagating in a circular tube, discovered experimentally in 1926, is simulated three-dimensionally with a detailed chemical reaction mechanism. The detonation front obtained numerically rotates periodically with a Mach leg, whiskers, and a transverse detonation. A long pressure trail, which is distributed from the transverse detonation to downstream, was reproduced, clearly showing that the pressure trail also spins synchronously with the transverse detonation. The formation of an unburned gas pocket behind the detonation front was not observed in the present simulations because the rotating transverse detonation completely consumed the unburned gas. The calculated profiles of instantaneous OH mass fraction have a keystone shape behind the detonation front. The numerical results for pitch, track angle, Mach stem angle, and incident shock angle on the tube wall agree well with the experimental results. (author)

  2. Double detonation drivers for a shock tube/tunnel

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong; FENG Heng; YU Hongru

    2004-01-01

    Recent progress on detonation drivers is reviewed. Performances of the forward detonation driver and backward detonation driver have been observed. To eliminate occurrence of a Taylor wave following the detonation wave in the primary driver and to improve the performance of the detonation driver, an additional backward detonation driver was proposed to attach to the end of the forward detonation driver.When the ratio of the initial pressures between the additional and the primary drivers becomes larger than or equal to a critical value, the Taylor wave will disappear, and thus a homogeneous driving gas with high pressure and high temperature can be generated.Furthermore, an over-driving detonation wave will be also obtained, which can increase the driving capability.

  3. Precursor detonation wave development in ANFO due to aluminum confinement

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Scott I [Los Alamos National Laboratory; Klyanda, Charles B [Los Alamos National Laboratory; Short, Mark [Los Alamos National Laboratory

    2010-01-01

    Detonations in explosive mixtures of ammonium-nitrate-fuel-oil (ANFO) confined by aluminum allow for transport of detonation energy ahead of the detonation front due to the aluminum sound speed exceeding the detonation velocity. The net effect of this energy transport on the detonation is unclear. It could enhance the detonation by precompressing the explosive near the wall. Alternatively, it could decrease the explosive performance by crushing porosity required for initiation by shock compression or destroying confinement ahead of the detonation. At present, these phenomena are not well understood. But with slowly detonating, non-ideal high explosive (NIHE) systems becoming increasing prevalent, proper understanding and prediction of the performance of these metal-confined NIHE systems is desirable. Experiments are discussed that measured the effect of this ANFO detonation energy transported upstream of the front by a 76-mm-inner-diameter aluminum confining tube. Detonation velocity, detonation-front shape, and aluminum response are recorded as a function of confiner wall thickness and length. Detonation shape profiles display little curvature near the confining surface, which is attributed to energy transported upstream modifying the flow. Average detonation velocities were seen to increase with increasing confiner thickness, while wavefront curvature decreased due to the stiffer, subsonic confinement. Significant radial sidewall tube motion was observed immediately ahead of the detonation. Axial motion was also detected, which interfered with the front shape measurements in some cases. It was concluded that the confiner was able to transport energy ahead of the detonation and that this transport has a definite effect on the detonation by modifying its characteristic shape.

  4. Detonation Performance Testing of LX-19

    Science.gov (United States)

    Vincent, Samuel; Aslam, Tariq; Jackson, Scott

    2015-06-01

    CL-20 was developed at the Naval Surface Weapons Center at China Lake, CA in the mid 80's. Being less sensitive than PETN, but considerably more powerful than HMX, it is the highest energy and density compound known among organic chemicals. LX-19 was developed at LLNL in the early 90's. It is a high-energy plastic bonded explosive, composed of 95.8 wt% CL-20 and 4.2 wt% Estane binder, and is similar to LX-14 (composed of HMX and Estane), but with greater sensitivity characteristics with use of the more energetic CL-20 explosive. We report detonation performance results for unconfined cylindrical rate sticks of LX-19. The experimental diameter effects are shown, along with detonation front shapes, and reaction zone profiles for different test diameters. This data is critical for calibration to Detonation Shock Dynamics (DSD). LA-UR-15-20672.

  5. Multistage reaction pathways in detonating high explosives

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kalia, Rajiv K.; Nakano, Aiichiro; Nomura, Ken-ichi; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)

    2014-11-17

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N{sub 2} and H{sub 2}O within ∼10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N{sub 2} and H{sub 2}O productions.

  6. Multistage reaction pathways in detonating high explosives

    International Nuclear Information System (INIS)

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N2 and H2O within ∼10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N2 and H2O productions

  7. Detonation Properties of Ammonium Dinitramide (ADN)

    Science.gov (United States)

    Wätterstam, A.; Östmark, H.; Helte, A.; Karlsson, S.

    1999-06-01

    Ammonium Dinitramide, ADN, has a potential as an oxidizer for underwater high explosives. Pure ADN has a large reaction-zone length and shows a strong non-ideal behaviour. The work presented here is an extension of previous work.(Sensitivity and Performance Characterization of Ammonium Dinitramide (ADN). Presented at 11th International Detonation Symposium, Snowmass, CO, 1998.) Experiments for determining the detonation velocity as a function of inverse charge radius and density, reaction-zone length and curvature, and the detonation pressure are presented. Measurements of pressure indicates that no, or weak von-Neumann spike exists, suggesting an immediate chemical decomposition. Experimental data are compared with predicted using thermochemical codes and ZND-theory.

  8. Diagnosing Common Benign Skin Tumors.

    Science.gov (United States)

    Higgins, James C; Maher, Michael H; Douglas, Mark S

    2015-10-01

    Patients will experience a wide range of skin growths and changes over their lifetime. Family physicians should be able to distinguish potentially malignant from benign skin tumors. Most lesions can be diagnosed on the basis of history and clinical examination. Lesions that are suspicious for malignancy, those with changing characteristics, symptomatic lesions, and those that cause cosmetic problems may warrant medical therapy, a simple office procedure (e.g., excision, cryosurgery, laser ablation), or referral. Acrochordons are extremely common, small, and typically pedunculated benign neoplasms. Simple scissor or shave excision, electrodesiccation, or cryosurgery can be used for treatment. Sebaceous hyperplasia presents as asymptomatic, discrete, soft, pale yellow, shiny bumps on the forehead or cheeks, or near hair follicles. Except for cosmesis, they have no clinical significance. Lipomas are soft, flesh-colored nodules that are easily moveable under the overlying skin. Keratoacanthomas are rapidly growing, squamoproliferative benign tumors that resemble squamous cell carcinomas. Early simple excision is recommended. Pyogenic granuloma is a rapidly growing nodule that bleeds easily. Treatment includes laser ablation or shave excision with electrodesiccation of the base. Dermatofibromas are an idiopathic benign proliferation of fibroblasts. No treatment is required unless there is a change in size or color, bleeding, or irritation from trauma. Epidermal inclusion cysts can be treated by simple excision with removal of the cyst and cyst wall. Seborrheic keratoses and cherry angiomas generally do not require treatment. PMID:26447443

  9. Familial benign pemphigus atypical localization

    OpenAIRE

    Reyes, Maria Veronica; Halac, Sabina; Mainardi, Claudio; Kurpis, Maria; Ruiz Lascano, Alejandro

    2016-01-01

    We present an atypical case of familial benign pemphigus (Hailey-Hailey disease), which presented as crusted, annular plaques limited to the back without intertriginous involvement. We could not find in the literature another patient with plaques located solely on the back without a prior history of classical disease.

  10. Pulse Detonation Engine Test Bed Developed

    Science.gov (United States)

    Breisacher, Kevin J.

    2002-01-01

    A detonation is a supersonic combustion wave. A Pulse Detonation Engine (PDE) repetitively creates a series of detonation waves to take advantage of rapid burning and high peak pressures to efficiently produce thrust. NASA Glenn Research Center's Combustion Branch has developed a PDE test bed that can reproduce the operating conditions that might be encountered in an actual engine. It allows the rapid and cost-efficient evaluation of the technical issues and technologies associated with these engines. The test bed is modular in design. It consists of various length sections of both 2- and 2.6- in. internal-diameter combustor tubes. These tubes can be bolted together to create a variety of combustor configurations. A series of bosses allow instrumentation to be inserted on the tubes. Dynamic pressure sensors and heat flux gauges have been used to characterize the performance of the test bed. The PDE test bed is designed to utilize an existing calorimeter (for heat load measurement) and windowed (for optical access) combustor sections. It uses hydrogen as the fuel, and oxygen and nitrogen are mixed to simulate air. An electronic controller is used to open the hydrogen and air valves (or a continuous flow of air is used) and to fire the spark at the appropriate times. Scheduled tests on the test bed include an evaluation of the pumping ability of the train of detonation waves for use in an ejector and an evaluation of the pollutants formed in a PDE combustor. Glenn's Combustion Branch uses the National Combustor Code (NCC) to perform numerical analyses of PDE's as well as to evaluate alternative detonative combustion devices. Pulse Detonation Engine testbed.

  11. Small Scale Detonation Studies: Direct impulse measurements for detonations and deflagrations

    OpenAIRE

    Austin, J. M.; Cooper, M.; S. Jackson; Wintenberger, E.; Shepherd, J. E.; Sturtevant, B.

    2000-01-01

    This report is an account of research carried out from January to June 2000 on the feasibility of detonation initiation and impulse generation for small-scale pulse detonation engines. The initial work was focussed on the direct measurement of impulse using the ballistic pendulum technique for single detonations initiated in a tube with one end open to the atmosphere through a thin diaphragm. Three tubes were used: (1) 38-mm diameter by 1.5 m long. (2) 75-mm diameter by 0.6 m long. (3) 75-mm ...

  12. Linear elastic response of tubes to internal detonation loading

    NARCIS (Netherlands)

    Beltman, W.M.; Shepherd, J.E.

    2002-01-01

    This paper deals with the structural response of a tube to an internal gaseous detonation. An internal detonation produces a pressure load that propagates down the tube. Because the speed of the gaseous detonation can be comparable to the flexural wave group speed, excitation of flexural waves in th

  13. 33 CFR 154.820 - Fire, explosion, and detonation protection.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Fire, explosion, and detonation... Systems § 154.820 Fire, explosion, and detonation protection. (a) A vapor control system with a single...: (1) Have a detonation arrester located not more than 6 meters (19.7 ft.) from the facility...

  14. MC3196 Detonator Shipping Package Hazard Classification Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Jones; Robert B.

    1979-05-31

    An investigation was made to determine whether the MC3196 detonator should be assigned a DOT hazard classification of Detonating Fuze, Class C Explosives per 49 CFR 173.113. This study covers the Propagation Test and the External Heat Test as approved by DOE Albuquerque Operations Office. Test data led to the recommeded hazard classification of detonating fuze, Class C explosives.

  15. Detonation wave problems : modeling, numerical simulations and linear stability

    OpenAIRE

    Carvalho, Filipe; Soares, A. J.

    2012-01-01

    Traveling waves arising in detonation physics are described by the reactive Euler equations obtained in the fluid dynamical limit of the Boltzmann equation for a binary reactive mixture. The hydrodynamic linear stability of the detonation wave solution is investigated with a normal mode analysis. Numerical simulations are performed for both the detonation wave solution and its linear stability.

  16. Approximate modeling of chemically reacting gas mixtures of detonation products

    International Nuclear Information System (INIS)

    Based on the assumption of the existence of the partial chemical equilibrium in the detonation products, an approximate method for calculating composition of the detonation products has been developed. The method uses the assumption of the existence of extremum of Helmholtz free energy for a given density, temperature, and molecular weight of the detonation products mixture

  17. Radiation cure of detonation transfer explosive

    International Nuclear Information System (INIS)

    The radiation cured detonation transfer plastic bonded explosive (PBX) provides the potential for achieving improvements in processability, storability, cure reproducibility, physical strength, and reliability of performance over the Navy's present injectable detonation transfer communications explosive. The composition and properties of the radiation cured system will be presented. Radiation cure of energetic materials is a relatively new process. It combines the advantages of an indefinitely long pot-life and storage life for the material mix with a very rapid cure. Neither of these features is available with conventional catalyzed thermal cure reactions. (Auth.)

  18. Statistical Hot Spot Model for Explosive Detonation

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, III, A L

    2005-07-14

    The Non-local Thermodynamic Equilibrium Statistical Hot Spot Model (NLTE SHS), a new model for explosive detonation, is described. In this model, the formation, ignition, propagation, and extinction of hot spots is explicitly modeled. The equation of state of the explosive mixture is treated with a non-local equilibrium thermodynamic assumption. A methodology for developing the parameters for the model is discussed, and applied to the detonation velocity diameter effect. Examination of these results indicates where future improvements to the model can be made.

  19. Statistical Hot Spot Model for Explosive Detonation

    Energy Technology Data Exchange (ETDEWEB)

    Nichols III, A L

    2004-05-10

    The Non-local Thermodynamic Equilibrium Statistical Hot Spot Model (NLTE SHS), a new model for explosive detonation, is described. In this model, the formation, ignition, propagation, and extinction of hot spots is explicitly modeled. The equation of state of the explosive mixture is treated with a nonlocal equilibrium thermodynamic assumption. A methodology for developing the parameters for the model is discussed, and applied to the detonation velocity diameter effect. Examination of these results indicates where future improvements to the model can be made.

  20. Modeling of steady plane thermal detonations

    International Nuclear Information System (INIS)

    Steady plane thermal detonations proceeding through coarse fuel-coolant mixtures have been predicted to exhibit pressures of approximately 104 bar for UO2/Na and approximately 103 bar for Sn/H2O1. Although detailed experimental information for the crucial fragmentation step is still largely lacking, some important preliminary conclusions can nevertheless be drawn from a detailed examination of the jump balances and solution of the steady, separated-flow conservation equations in the fragmentation zone behind the shock. A few key results are presented of some parametric calculations of steady plane thermal detonations, and in addition offer some broader comments. 33 references

  1. Investigation of hydrogen-deflagration/-detonation

    International Nuclear Information System (INIS)

    The static and dynamic loads of a PWR-containment from hydrogen combustion are investigated theoretically and experimentally. The primary goal is the determination of realistic, not too conservative, upper bounds. The load data are needed to define design requirements for a core-melt resistant containment structure. The following work was performed in 1991: balloon tests; design of a medium scale detonation tube; development of a 1D detonation code; analytical study with SNL/Albuquerque, USA and documentation and presentation of results. (orig./DG)

  2. Detonation Initiation via Imploding Shock Waves

    OpenAIRE

    Jackson, S. I.; Shepherd, J. E.

    2004-01-01

    An imploding annular shock wave driven by a jet of air was used to initiate detonations inside a 76 mm diameter tube. The tube was filled with a test gas composed of either stoichiometric ethylene-oxygen or propane-oxygen diluted with nitrogen. The strength of the imploding shock wave and the sensitivity of the test gas were varied in an effort to find the minimum shock strength required for detonation of each test mixture. The results show that the minimum required shock stren...

  3. Study of the Detonation Phase in the Gravitationally Confined Detonation Model of Type Ia Supernovae

    CERN Document Server

    Meakin, Casey A; Townsley, Dean; Jordan, George C; Truran, James; Lamb, Don

    2008-01-01

    We study the gravitationally confined detonation (GCD) model of Type Ia supernovae through the detonation phase and into homologous expansion. In the GCD model, a detonation is triggered by the surface flow due to single point, off-center flame ignition in carbon-oxygen white dwarfs. The simulations are unique in terms of the degree to which non-idealized physics is used to treat the reactive flow, including weak reaction rates and a time dependent treatment of material in nuclear statistical equilibrium (NSE). Careful attention is paid to accurately calculating the final composition of material which is burned to NSE and frozen out in the rapid expansion following the passage of a detonation wave over the high density core of the white dwarf; and an efficient method for nucleosynthesis post-processing is developed which obviates the need for costly network calculations along tracer particle thermodynamic trajectories. Observational diagnostics are presented for the explosion models, including abundance strat...

  4. Detonation re-initiation mechanism following the Mach reflection of a quenched detonation

    OpenAIRE

    Bhattacharjee, Rohit; Lau-Chapdelaine, Sebastien She Ming; Maines, Geoffrey; Maley, Logan; Radulescu, Matei Ioan

    2012-01-01

    This experimental study addresses the re-initiation mechanism of detonation waves following the Mach reflection of a shock-flame complex. The detonation diffraction around a cylinder is used to reproducibly generate the shock-flame complex of interest. The experiments are performed in methane-oxygen. We use a novel experimental technique of coupling a two-in-line-spark flash system with a double-frame camera in order to obtain microsecond time resolution permitting accurate schlieren velocime...

  5. Ethylene-air detonation in water spray

    Science.gov (United States)

    Jarsalé, G.; Virot, F.; Chinnayya, A.

    2016-07-01

    Detonation experiments are conducted in a 52 mm square channel with an ethylene-air gaseous mixture with dispersed liquid water droplets. The tests were conducted with a fuel-air equivalence ratio ranging from 0.9 to 1.1 at atmospheric pressure. An ultrasonic atomizer generates a polydisperse liquid water spray with droplet diameters of 8.5-12 μm, yielding an effective density of 100-120 g/m3 . Pressure signals from seven transducers and cellular structure are recorded for each test. The detonation structure in the two-phase mixture exhibits a gaseous-like behaviour. The pressure profile in the expansion fan is not affected by the addition of water. A small detonation velocity deficit of up to 5 % was measured. However, the investigation highlights a dramatic increase in the cell size (λ ) associated with the increase in the liquid water mass fraction in the two-phase mixture. The detonation structure evolves from a multi-cell to a half-cell mode. The analysis of the decay of the post-shock pressure fluctuations reveals that the ratio of the hydrodynamic thickness over the cell size (x_{{HT}}/{λ } ) remains quite constant, between 5 and 7. A slight decrease of this ratio is observed as the liquid water mass fraction is increased, or the ethylene-air mixture is made leaner.

  6. Detonation characteristics of ammonium nitrate products

    NARCIS (Netherlands)

    Kersten, R.J.A.; Hengel, E.I.V. van den; Steen, A.C. van der

    2006-01-01

    The detonation properties of ammonium nitrate (AN) products depend on many factors and are therefore, despite the large amount of information on this topic, difficult to assess. In order to further improve the understanding of the safety properties of AN, the European Fertilizer Manufacturers Associ

  7. Formation of transverse waves in oblique detonations

    NARCIS (Netherlands)

    Verreault, J.; Higgins, A.J.; Stowe, R.A.

    2013-01-01

    The structure of oblique detonation waves stabilized on a hypersonic wedge in mixtures characterized by a large activation energy is investigated via steady method of characteristics (MoC) calculations and unsteady computational flowfield simulations. The steady MoC solutions show that, after the tr

  8. Detonation propagation in a high loss configuration

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Scott I [Los Alamos National Laboratory; Shepherd, Joseph E [CALTECH

    2009-01-01

    This work presents an experimental study of detonation wave propagation in tubes with inner diameters (ID) comparable to the mixture cell size. Propane-oxygen mixtures were used in two test section tubes with inner diameters of 1.27 mm and 6.35 mm. For both test sections, the initial pressure of stoichiometric mixtures was varied to determine the effect on detonation propagation. For the 6.35 mm tube, the equivalence ratio {phi} (where the mixture was {phi} C{sub 3}H{sub 8} + 50{sub 2}) was also varied. Detonations were found to propagate in mixtures with cell sizes as large as five times the diameter of the tube. However, under these conditions, significant losses were observed, resulting in wave propagation velocities as slow as 40% of the CJ velocity U{sub CJ}. A review of relevant literature is presented, followed by experimental details and data. Observed velocity deficits are predicted using models that account for boundary layer growth inside detonation waves.

  9. Detonation duct gas generator demonstration program

    Science.gov (United States)

    Wortman, Andrew; Brinlee, Gayl A.; Othmer, Peter; Whelan, Michael A.

    1991-01-01

    The feasibility of the generation of detonation waves moving periodically across high speed channel flow is experimentally demonstrated. Such waves are essential to the concept of compressing requirements and increasing the engine pressure compressor with the objective of reducing conventional compressor requirements and increasing the engine thermodynamic efficiency through isochoric energy addition. By generating transient transverse waves, rather than standing waves, shock wave losses are reduced by an order of magnitude. The ultimate objective is to use such detonation ducts downstream of a low pressure gas turbine compressor to produce a high overall pressure ratio thermodynamic cycle. A 4 foot long, 1 inch x 12 inch cross-section, detonation duct was operated in a blow-down mode using compressed air reservoirs. Liquid or vapor propane was injected through injectors or solenoid valves located in the plenum or the duct itself. Detonation waves were generated when the mixture was ignited by a row of spark plugs in the duct wall. Problems with fuel injection and mixing limited the air speeds to about Mach 0.5, frequencies to below 10 Hz, and measured pressure ratios of about 5 to 6. The feasibility of the gas dynamic compression was demonstrated and the critical problem areas were identified.

  10. Hydrogen detonation and detonation transition data from the High-Temperature Combustion Facility

    Energy Technology Data Exchange (ETDEWEB)

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C. [Brookhaven National Lab., Upton, NY (United States)] [and others

    1996-03-01

    The BNL High-Temperature Combustion Facility (HTCF) is an experimental research tool capable of investigating the effects of initial thermodynamic state on the high-speed combustion characteristic of reactive gas mixtures. The overall experimental program has been designed to provide data to help characterize the influence of elevated gas-mixture temperature (and pressure) on the inherent sensitivity of hydrogen-air-steam mixtures to undergo detonation, on the potential for flames accelerating in these mixtures to transition into detonations, on the effects of gas venting on the flame-accelerating process, on the phenomena of initiation of detonations in these mixtures by jets of hot reactant products, and on the capability of detonations within a confined space to transmit into another, larger confined space. This paper presents results obtained from the completion of two of the overall test series that was designed to characterize high-speed combustion phenomena in initially high-temperature gas mixtures. These two test series are the intrinsic detonability test series and the deflagration-to-detonation (DDT) test series. A brief description of the facility is provided below.

  11. Hydrogen detonation and detonation transition data from the High-Temperature Combustion Facility

    International Nuclear Information System (INIS)

    The BNL High-Temperature Combustion Facility (HTCF) is an experimental research tool capable of investigating the effects of initial thermodynamic state on the high-speed combustion characteristic of reactive gas mixtures. The overall experimental program has been designed to provide data to help characterize the influence of elevated gas-mixture temperature (and pressure) on the inherent sensitivity of hydrogen-air-steam mixtures to undergo detonation, on the potential for flames accelerating in these mixtures to transition into detonations, on the effects of gas venting on the flame-accelerating process, on the phenomena of initiation of detonations in these mixtures by jets of hot reactant products, and on the capability of detonations within a confined space to transmit into another, larger confined space. This paper presents results obtained from the completion of two of the overall test series that was designed to characterize high-speed combustion phenomena in initially high-temperature gas mixtures. These two test series are the intrinsic detonability test series and the deflagration-to-detonation (DDT) test series. A brief description of the facility is provided below

  12. Hydrogen detonation and detonation transition data from the High-Temperature Combustion Facility

    International Nuclear Information System (INIS)

    The BNL High-Temperature Combustion Facility (HTCF) is an experimental research tool capable of investigating the effects of initial thermodynamic state on the high-speed combustion characteristic of reactive gas mixtures. The overall experimental program has been designed to provide data to help characterize the influence of elevated gas-mixture temperature (and pressure) on the inherent sensitivity of hydrogen-air-steam mixtures to undergo detonation, on the potential for flames accelerating in these mixtures to transition into detonations, on the effects of gas venting on the flame-accelerating process, on the phenomena of initiation of detonations in these mixtures by jets of hot reactant product,s and on the capability of detonations within a confined space to transmit into another, larger confined space. This paper presents results obtained from the completion of two of the overall test series that was designed to characterize high-speed combustion phenomena in initially high-temperature gas mixtures. These two test series are the intrinsic detonability test series and the deflagration-to-detonation (DDT) test series. A brief description of the facility is provided below

  13. Cellular structure of detonation utilized in propulsion system

    Science.gov (United States)

    Zhang, XuDong; Fan, BaoChun; Gui, MingYue; Pan, ZhenHua

    2012-10-01

    How to confine a detonation in a combustor is a key issue of detonation applications in propulsion systems. Based on achieving schemes, detonations applied in the combustor, including pulse detonation wave (PDW), oblique detonation wave (ODW) and rotating detonation wave (RDW), are different from that described by the classic CJ theory in fine structures and its self-sustaining mechanisms. In this work, the cellular structures and flow fields of ODW and RDW were obtained numerically, and the fundamental characteristics and self-sustaining mechanisms of the detonations were analyzed and discussed. ODW front consists of three parts: the ZND-like front, the single-headed triple point front and the dual-headed triple point front. Cellular structures of RDW are heterogeneous, and the cell size near the outer wall is smaller than that near the inner wall.

  14. BENIGN PROSTATIC HYPERPLASIA: UPDATED REVIEW

    OpenAIRE

    Praveen.R

    2013-01-01

    Benign Prostatic Hyperplasia (BPH) is one of the commonest medical conditions affecting the geriatric male population. The enlargement of prostate can lead to various clinical symptoms like difficulty in voiding, urinary retention etc. The symptoms are varied depending on the size of enlargement. The International Prostatic Symptom Score (IPSS) is the gold standard and first step in understanding and diagnosing the disease clinically, but in the recent past there are various other newer tools...

  15. Benign tumours of the vulva

    International Nuclear Information System (INIS)

    Objective: To present clinicopathological analysis of benign tumours of the vulva. Patients and Methods: Thirty cases of benign tumours of vulva were studied during 2 years research period. Detailed history along with complete local and general physical examination followed by all necessary pre-operative investigations were carried out. Excision surgery was the treatment of choice in majority of cases while marsupialization was done for Bartholin's cyst. Histopathology of tumours specimen was also collected. Results: A total of 30 cases were studied. Twenty-two were cystic and 8 were solid tumours. Aggressive angiomyxoma was 10% of solid tumours and Bartholin's cyst was 46.6% of cystic tumours. Most of the patients were multipara and between 21-30 years of age. The main site of tumour was labium majus. Excision surgery for all cases and marsupialization for Bartholin's cyst was treatment of choice. Conclusion: Aggressive angiomyxoma is the commonest solid benign vulval tumour. It should be considered in the differential diagnosis of vulval mass in women of reproductive age. (author)

  16. Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power

    Science.gov (United States)

    Litchford, R. J.; Lyles, Garry M. (Technical Monitor)

    2001-01-01

    The prospects for realizing an integrated pulse detonation propulsion and magnetohydrodynamic (MHD) power system are examined. First, energy requirements for direct detonation initiation of various fuel-oxygen and fuel-air mixtures are deduced from available experimental data and theoretical models. Second, the pumping power requirements for effective chamber scavenging are examined through the introduction of a scavenging ratio parameter and a scavenging efficiency parameter. A series of laboratory experiments were carried out to investigate the basic engineering performance characteristics of a pulse detonation-driven MHD electric power generator. In these experiments, stoichiometric oxy-acetylene mixtures seeded with a cesium hydroxide/methanol spray were detonated at atmospheric pressure in a 1-m-long tube having an i.d. of 2.54 cm. Experiments with a plasma diagnostic channel attached to the end of the tube confirmed the attainment of detonation conditions (p(sub 2)/p(sub 1) approx. 34 and D approx. 2,400 m/sec) and enabled the direct measurement of current density and electrical conductivity (=6 S/m) behind the detonation wave front. In a second set of experiments, a 30-cm-long continuous electrode Faraday channel, having a height of 2.54 cm and a width of 2 cm, was attached to the end of the tube using an area transition duct. The Faraday channel was inserted in applied magnetic fields of 0.6 and 0.95 T. and the electrodes were connected to an active loading circuit to characterize power extraction dependence on load impedance while also simulating higher effective magnetic induction. The experiments indicated peak power extraction at a load impedance between 5 and 10 Ohm. The measured power density was in reasonable agreement with a simple electrodynamic model incorporating a correction for near-electrode potential losses. The time-resolved thrust characteristics of the system were also measured, and it was found that the MHD interaction exerted a

  17. Numerical simulation of spinning detonation in circular section channels

    Science.gov (United States)

    Levin, V. A.; Manuylovich, I. S.; Markov, V. V.

    2016-06-01

    Numerical simulation of three-dimensional structures of gas detonation in circular section channels that emerge due to the instability when the one-dimensional flow is initiated by energy supply at the closed end of the channel is performed. It is found that in channels with a large diameter, an irregular three-dimensional cellular detonation structure is formed. Furthermore, it is found that in channels with a small diameter circular section, the initially plane detonation wave is spontaneously transformed into a spinning detonation wave, while passing through four phases. A critical value of the channel diameter that divides the regimes with the three-dimensional cellular detonation and spinning detonation is determined. The stability of the spinning detonation wave under perturbations occurring when the wave passes into a channel with a greater (a smaller) diameter is investigated. It is found that the spin is preserved if the diameter of the next channel (into which the wave passes) is smaller (respectively, greater) than a certain critical value. The computations were performed on the Lomonosov supercomputer using from 0.1 to 10 billions of computational cells. All the computations of the cellular and spinning detonation were performed in the whole long three-dimensional channel (up to 1 m long) rather than only in its part containing the detonation wave; this made it possible to adequately simulate and investigate the features of the transformation of the detonation structure in the process of its propagation.

  18. Precursors in detonations in porous explosives

    International Nuclear Information System (INIS)

    Photographs of detonation waves in low-density HMX and PETN, made with an image-intensifier camera, show a brilliant band of light in front of the pressure jump. The radiation temperature is estimated to be 12,000 to 14,0000K. The spectrum of this light is continuous. A quartz gauge shows a gradual buildup of pressure from the material producing the light. The material has little effect on the propagation of detonation. Further observations, using pellets of plastic-bonded HMX and single crystals of PETN, show that the material thrown off the free surface is transparent, with a leading edge moving at approximately 20 mm/μs. Collision of this material with polymethyl methacrylate (PMMA) produces a brilliant light with a spectrum that is initially a narrow H/sub α/ line. Quartz gauges measure the rate of pessure buildup of this material

  19. Pulse Detonation Engines for High Speed Flight

    Science.gov (United States)

    Povinelli, Louis A.

    2002-01-01

    Revolutionary concepts in propulsion are required in order to achieve high-speed cruise capability in the atmosphere and for low cost reliable systems for earth to orbit missions. One of the advanced concepts under study is the air-breathing pulse detonation engine. Additional work remains in order to establish the role and performance of a PDE in flight applications, either as a stand-alone device or as part of a combined cycle system. In this paper, we shall offer a few remarks on some of these remaining issues, i.e., combined cycle systems, nozzles and exhaust systems and thrust per unit frontal area limitations. Currently, an intensive experimental and numerical effort is underway in order to quantify the propulsion performance characteristics of this device. In this paper, we shall highlight our recent efforts to elucidate the propulsion potential of pulse detonation engines and their possible application to high-speed or hypersonic systems.

  20. Prompt Reaction of Aluminum in Detonating Explosives

    International Nuclear Information System (INIS)

    The potential of aluminum (Al) reaction to boost detonation energy has been studied for decades, most recently spurred by the availability of nanometer-sized particles. A literature review is consistent with results from the small-scale shock reactivity test (SSRT). In this test, <1/2-g samples in confinement are shock loaded on one end, and the output at the other end dents a soft witness block. For samples in which 0.3 g of cyclotetramethylenetetranitramine (HMX) was mixed with 8 μm Al, the deepest dent occurred at 15% Al. When ammonium perchlorate (AP) was mixed with the same Al, the increased dents were consistent with changes in detonation velocity previously reported on similar mixtures. One outcome of this study is a new interpretation for the participation of Al in large scale gap tests on plastic-bonded explosives, which was discussed by Bernecker at this meeting in 1987

  1. A transient model to the thermal detonation

    International Nuclear Information System (INIS)

    The model calculates the escalation dynamics and the long time behavior of thermal detonation waves depending on the initial and boundary conditions (data of the premixture, ignition at a solid wall or at an open end, etc.). Especially, for a given mixture and a certain fragmentation behavior more than one stable steady-state cases resulted, depending on the applied ignition energy. Investigations showed a very good consistency between the transient model and a steady-state model which is based on the same physical description and includes an additional stability criterion. Also the influence of effects such as e.g. non-homogeneous coolant heating, spherical instead of plane wave propagation and inhomogeneities of the premixture on the development of the wave were investigated. Comparison calculations with large scale experiments showed that they can be well explained by means of the thermal detonation theory, especially considering the transient phase of the wave development. (orig./HP)

  2. Pulse Detonation Rocket Magnetohydrodynamic Power Experiment

    Science.gov (United States)

    Litchford, R. J.; Jones, J. E.; Dobson, C. C.; Cole, J. W.; Thompson, B. R.; Plemmons, D. H.; Turner, M. W.

    2003-01-01

    The production of onboard electrical power by pulse detonation engines is problematic in that they generate no shaft power; however, pulse detonation driven magnetohydrodynamic (MHD) power generation represents one intriguing possibility for attaining self-sustained engine operation and generating large quantities of burst power for onboard electrical systems. To examine this possibility further, a simple heat-sink apparatus was developed for experimentally investigating pulse detonation driven MHD generator concepts. The hydrogen oxygen fired driver was a 90 cm long stainless steel tube having a 4.5 cm square internal cross section and a short Schelkin spiral near the head end to promote rapid formation of a detonation wave. The tube was intermittently filled to atmospheric pressure and seeded with a CsOH/methanol prior to ignition by electrical spark. The driver exhausted through an aluminum nozzle having an area contraction ratio of A*/A(sub zeta) = 1/10 and an area expansion ratio of A(sub zeta)/A* = 3.2 (as limited by available magnet bore size). The nozzle exhausted through a 24-electrode segmented Faraday channel (30.5 cm active length), which was inserted into a 0.6 T permanent magnet assembly. Initial experiments verified proper drive operation with and without the nozzle attachment, and head end pressure and time resolved thrust measurements were acquired. The exhaust jet from the nozzle was interrogated using a polychromatic microwave interferometer yielding an electron number density on the order of 10(exp 12)/cm at the generator entrance. In this case, MHD power generation experiments suffered from severe near-electrode voltage drops and low MHD interaction; i.e., low flow velocity, due to an inherent physical constraint on expansion with the available magnet. Increased scaling, improved seeding techniques, higher magnetic fields, and higher expansion ratios are expected to greatly improve performance.

  3. Thermonuclear detonations ensuing white dwarf mergers

    OpenAIRE

    Dan, Marius; Guillochon, James; Brüggen, Marcus; Ramirez-Ruiz, Enrico; Rosswog, Stephan

    2015-01-01

    The merger of two white dwarfs (WDs) has for many years not been considered as the favoured model for the progenitor system of type Ia supernovae (SNe Ia). But recent years have seen a change of opinion as a number of studies, both observational and theoretical, have concluded that they should contribute significantly to the observed type Ia supernova rate. In this paper, we study the ignition and propagation of detonation through post-merger remnants and we follow the resulting nucleosynthes...

  4. Exergy Analysis in Hydrogen-Air Detonation

    OpenAIRE

    Abel Rouboa; Valter Silva; Nuno Couto

    2012-01-01

    The main goal of this paper is to analyze the exergy losses during the shock and rarefaction wave of hydrogen-air mixture. First, detonation parameters (pressure, temperature, density, and species mass fraction) are calculated for three cases where the hydrogen mass fraction in air is 1.5%, 2.5%, and 5%. Then, exergy efficiency is used as objective criteria of performance evaluation. A two-dimensional computational fluid dynamic code is developed using Finite volume discretization method coup...

  5. A numerical study of detonation diffraction

    OpenAIRE

    Arienti, Marco; Shepherd, J. E.

    2005-01-01

    An investigation of detonation diffraction through an abrupt area change has been carried out via a set of two-dimensional numerical simulations parameterized by the activation energy of the reactant. Our analysis is specialized to a reactive mixture with a perfect gas equation of state and a single-step reaction in the Arrhenius form. Lagrangian particles are injected into the flow as a diagnostic tool for identifying the dominant terms in the equation that describes the temperature rate of ...

  6. Stability of viscous detonations for Majda's model

    OpenAIRE

    Humpherys, Jeffrey; Lyng, Gregory; Zumbrun, Kevin

    2013-01-01

    Using analytical and numerical Evans-function techniques, we examine the spectral stability of strong-detonation-wave solutions of Majda's scalar model for a reacting gas mixture with an Arrhenius-type ignition function. We introduce an efficient energy estimate to limit possible unstable eigenvalues to a compact region in the unstable complex half plane, and we use a numerical approximation of the Evans function to search for possible unstable eigenvalues in this region. Our results show, fo...

  7. Detonation Diffraction Through a Mixture Gradient

    OpenAIRE

    Schultz, E.; Shepherd, J

    2000-01-01

    A simple one-dimensional model of a self-propagating gaseous detonation consists of a shock wave tightly coupled to a reaction zone, propagating through a combustible gas mixture as shown in Fig. 1 (Strehlow 1984). A feedback mechanism exists in that the shock wave generates the thermodynamic conditions under which the gas combusts, and the energy release from the reaction zone maintains the strength of the shock This is in contrast to a flame, or deflagrative combustion, in which thermal and...

  8. Multistage reaction pathways in detonating high explosives

    Science.gov (United States)

    Li, Ying; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya; CACS Collaboration; ALCF Team

    2015-06-01

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N2 and H2O within 10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct uni-molecular and intermolecular reaction pathways, respectively, for the rapid N2 and H2O productions. This work was supported by the Office of Naval Research Grant No. N000014-12-1-0555 and the Basic Research Program of Defense Threat Reduction Agency (DTRA) Grant No. HDTRA1-08-1-0036. All the simulations were performed at USC and Argonne LCF.

  9. A gasdynamic gun driven by gaseous detonation.

    Science.gov (United States)

    Li, Jinping; Chen, Hong; Zhang, Shizhong; Zhang, Xiaoyuan; Yu, Hongru

    2016-01-01

    A gasdynamic gun driven by gaseous detonation was developed to address the disadvantages of the insufficient driving capability of high-pressure gas and the constraints of gunpowder. The performance of this gasdynamic gun was investigated through experiments and numerical simulations. Much more powerful launching capability was achieved by this gun relative to a conventional high-pressure gas gun, owing to the use of the chemical energy of the driver gas. To achieve the same launching condition, the initial pressure required for this gun was an order of magnitude lower than that for a gun driven by high-pressure H2. Because of the presence of the detonation, however, a more complex internal ballistic process of this gun was observed. Acceleration of projectiles for this gun was accompanied by a series of impulse loads, in contrast with the smooth acceleration for a conventional one, which indicates that this gun should be used conditionally. The practical feasibility of this gun was verified by experiments. The experiments demonstrated the convenience of taking advantage of the techniques developed for detonation-driven shock tubes and tunnels. PMID:26827358

  10. The Spherical Relativistic Detonation of Scalaron Stars

    CERN Document Server

    Folomeev, V N; Usupov, R

    2000-01-01

    Now the hypothesis of existence of scalar fields of a various nature and energy density in the modern Universe is intensively explored. It can explain a nature of the dark (non- baryon) matter in the Universe and an existence of positive $\\Lambda $-term (see e.g. gr-qc/9904398). One of component of such field has a cluster nature and organizes in the closed gravitational configurations from galactic scales up to relativistic microscopic stars. In the authors paper astro-ph/0008334 the hypothesis of detonation of such fields was considered. As a result of phase transition behind the wavefront a relativistic plasma of high energy density can appear. This process is similar to a relativistic detonation and it can create macroscopic fireballs sufficient for an explanation of the phenomenon of gamma-ray bursts (see e.g. the review astro-ph/9907392). In astro-ph/0008334 it was supposed that the front of such ''detonation'' wave is entered by the flow of scalar fields with constant energy density. If the size of the...

  11. Characterizing detonator output using dynamic witness plates

    International Nuclear Information System (INIS)

    A sub-microsecond, time-resolved micro-particle-image velocimetry (PIV) system is developed to investigate the output of explosive detonators. Detonator output is directed into a transparent solid that serves as a dynamic witness plate and instantaneous shock and material velocities are measured in a two-dimensional plane cutting through the shock wave as it propagates through the solid. For the case of unloaded initiators (e.g. exploding bridge wires, exploding foil initiators, etc.) the witness plate serves as a surrogate for the explosive material that would normally be detonated. The velocity-field measurements quantify the velocity of the shocked material and visualize the geometry of the shocked region. Furthermore, the time-evolution of the velocity-field can be measured at intervals as small as 10 ns using the PIV system. Current experimental results of unloaded exploding bridge wire output in polydimethylsiloxane (PDMS) witness plates demonstrate 20 MHz velocity-field sampling just 300 ns after initiation of the wire.

  12. Plasma Sensor Measurements in Pulse Detonation Engines

    Science.gov (United States)

    Matlis, Eric; Marshall, Curtis; Corke, Thomas; Gogineni, Sivaram

    2014-11-01

    Measurements have been conducted in a pulse detonation and rotating detonation engine using a newly developed plasma sensor. This sensor relies on the novel approach of using an ac-driven, weakly-ionized electrical discharge as the main sensing element. The advantages of this approach include a native high bandwidth of 1 MHz without the need for electronic frequency compensation, a dual-mode capability that provides sensitivity to multiple flow parameters, including velocity, pressure, temperature, and gas-species, and a simple and robust design making it very cost effective. The sensor design is installation-compatible with conventional sensors commonly used in gas-turbine research such as the Kulite dynamic pressure sensor while providing much better longevity. Developmental work was performed in high temperature facilities that are relevant to the propulsion and high-speed research community. This includes tests performed in a J85 augmentor at full afterburner and pulse-detonation engines at the University of Cincinnati (UC) at temperatures approaching 2760°C (5000°F).

  13. Fragmentation requirements for detonating thermal explosions

    International Nuclear Information System (INIS)

    The mechanism of thermal explosions, which are of interest when evaluating nuclear reactor safety factors, is considered. Such explosions are caused by the contact of a hot with a cold liquid developing into a rapid thermal interaction in which a significant fraction (approaching the thermodynamic limits) of the thermal energy in the hot liquid is converted into mechanical work. Board et al (Nature; 254:319 (1975)) proposed the use of classical detonation theory in conjunction with a mechanism of pressure wave-induced fragmentation of liquid fuel drops premixed (coarsely) with the liquid coolant, the quantitative aspects of which were based on existing measurements in gas-water systems as an approach to understanding such explosions. Here, studies of fragmentation of high surface tension liquid drops (mercury) in a liquid medium (water) in which it was found that the fragmentation behaviour is considerably different from that in the gas-water system are reported. The results reveal a different behaviour than that expected from previous work and it is shown that the pressure pulse trigger requirements for the detonation model proposed by Board et al are drastically reduced compared with the original estimates of those workers. It is emphasised that fragmentation is only one aspect of the explosion process and suggestions are made of other mechanisms which must be investigated in order to assess the conditions of applicability of the detonation model. (U.K.)

  14. A gasdynamic gun driven by gaseous detonation

    Science.gov (United States)

    Li, Jinping; Chen, Hong; Zhang, Shizhong; Zhang, Xiaoyuan; Yu, Hongru

    2016-01-01

    A gasdynamic gun driven by gaseous detonation was developed to address the disadvantages of the insufficient driving capability of high-pressure gas and the constraints of gunpowder. The performance of this gasdynamic gun was investigated through experiments and numerical simulations. Much more powerful launching capability was achieved by this gun relative to a conventional high-pressure gas gun, owing to the use of the chemical energy of the driver gas. To achieve the same launching condition, the initial pressure required for this gun was an order of magnitude lower than that for a gun driven by high-pressure H2. Because of the presence of the detonation, however, a more complex internal ballistic process of this gun was observed. Acceleration of projectiles for this gun was accompanied by a series of impulse loads, in contrast with the smooth acceleration for a conventional one, which indicates that this gun should be used conditionally. The practical feasibility of this gun was verified by experiments. The experiments demonstrated the convenience of taking advantage of the techniques developed for detonation-driven shock tubes and tunnels.

  15. Transition from slow deflagration to detonation

    International Nuclear Information System (INIS)

    A literature search on the safety of nuclear power plants in the presence of external gas cloud explosions is reported. It includes literature up to the beginning of 1983. After presenting the current licensing situation in the Federal Republic of Germany, some recent work on damage analysis of real vapour cloud explosions is discussed. Experiments with real vapour clouds and free hydrogen-air clouds are reported. The transition from deflagration to detonation is discussed in several steps - the transition in long tubes when the flame is confined, in partially confined hydrogen-air clouds and the jet ignition of free gas clouds. The last two are large scale experiments done in the Prototype Nuclear Process Heat programme. The conclusions are that even partial confinement of a hydrogen-air cloud leads to pressure build-up, jet ignition of a gas cloud must be avoided, detonative ignition has to be excluded and turbulence generating structures, eg grids, only produce a local pressure build-up and do not lead to a transition from deflagration to detonation. (U.K.)

  16. Numerical simulation of spinning detonation in square tube

    Science.gov (United States)

    Tsuboi, Nobuyuki; Asahara, Makoto; Eto, Keitaro; Hayashi, A. Koichi

    2008-09-01

    A single spinning detonation wave propagating in a square tube is simulated three-dimensionally with the detailed chemical reaction mechanism for hydrogen/air mixture proposed by Petersen and Hanson. The spinning detonation is composed of a transverse detonation rotating around the wall normal to the tube axis, triple lines propagating partially out of phase, and a short pressure trail. The formation of an unburned gas pocket behind the detonation front was not observed in the present simulations because the rotating transverse detonation completely consumed the unburned gas. The calculated profiles of instantaneous OH mass fraction have a keystone shape behind the detonation front. The numerical results for the pitch and track angle on the tube wall agree well with the experimental results.

  17. Insensitive detonator apparatus for initiating large failure diameter explosives

    Science.gov (United States)

    Perry, III, William Leroy

    2015-07-28

    A munition according to a preferred embodiment can include a detonator system having a detonator that is selectively coupled to a microwave source that functions to selectively prime, activate, initiate, and/or sensitize an insensitive explosive material for detonation. The preferred detonator can include an explosive cavity having a barrier within which an insensitive explosive material is disposed and a waveguide coupled to the explosive cavity. The preferred system can further include a microwave source coupled to the waveguide such that microwaves enter the explosive cavity and impinge on the insensitive explosive material to sensitize the explosive material for detonation. In use the preferred embodiments permit the deployment and use of munitions that are maintained in an insensitive state until the actual time of use, thereby substantially preventing unauthorized or unintended detonation thereof.

  18. Future Modeling Needs in Pulse Detonation Rocket Engine Design

    Science.gov (United States)

    Meade, Brian; Talley, Doug; Mueller, Donn; Tew, Dave; Guidos, Mike; Seymour, Dave

    2001-01-01

    This paper presents a performance model rocket engine design that takes advantage of pulse detonation to generate thrust. The contents include: 1) Introduction to the Pulse Detonation Rocket Engine (PDRE); 2) PDRE modeling issues and options; 3) Discussion of the PDRE Performance Workshop held at Marshall Space Flight Center; and 4) Identify needs involving an open performance model for Pulse Detonation Rocket Engines. This paper is in viewgraph form.

  19. Combustion and Magnetohydrodynamic Processes in Advanced Pulse Detonation Rocket Engines

    OpenAIRE

    Cole, Lord Kahil

    2012-01-01

    A number of promising alternative rocket propulsion concepts have been developed over the past two decades that take advantage of unsteady combustion waves in order to produce thrust. These concepts include the Pulse Detonation Rocket Engine (PDRE), in which repetitive ignition, propagation, and reflection of detonations and shocks can create a high pressure chamber from which gases may be exhausted in a controlled manner. The Pulse Detonation Rocket Induced Magnetohydrodynamic Ejector (PDRIM...

  20. Determination of detonation wave velocity in an explosive gas mixture

    International Nuclear Information System (INIS)

    The well-known formula for the flat detonation wave velocity derived from the Hugoniot system of equations faces difficulties, if being applied to a spherical reactor. A similar formula has been obtained in the framework of the theory of explosion in reacting gas media with the use of a special model describing the transition of an explosive wave in the detonation. The derived formula is very simple, being also more suitable for studying the limiting processes of volume detonation.

  1. Detonation Initiation in a Tube via Imploding Toroidal Shock Waves

    OpenAIRE

    Jackson, S. I.; Shepherd, J. E.

    2008-01-01

    The effectiveness of imploding waves at detonation initiation of stoichiometric ethylene- and propane–oxygen– nitrogen mixtures in a tube was investigated. Implosions were driven by twice-shocked gas located at the end of a shock tube, and wave strength was varied to determine the critical conditions necessary for initiation as a function of diluent concentration for each fuel. Hydrocarbon–air mixtures were not detonated due to facility limitations, however, detonations were achie...

  2. A Novel Oblique Detonation Structure and Its Stability

    Institute of Scientific and Technical Information of China (English)

    TENG Hong-Hui; ZHAO Wei; JIANG Zong-Lin

    2007-01-01

    Oblique detonation structures induced by the wedge in the supersonic combustible gas mixtures are simulated numerically. The results show that the stationary oblique detonation structures are influenced by the gas flow Mach number, and a novel critical oblique detonation structure, which is characterized by a more complicated wave system, appears in the low Mach number cases. By introducing the inflow disturbance, its nonstationary evolution process is illustrated and its stability is verified.

  3. Research into the Detonation of Non Ideal Versus Ideal Explosives

    OpenAIRE

    Miller, R.; Goldwasser, J.

    1995-01-01

    The objectives are to determine, understand, and control the mechanisms and the rates of energy release in metallized explosive compositions during the detonation state and in the post-detonation regime. The goals of the initiative are to : (i) account for the total energy and the rates of energy release in the underwater detonation of a composite metallized explosive, (ii) establish and demonstrate concepts which can be employed to "dial" the near field pressure/time profile in order to maxi...

  4. On the Energy Evolution in Gaseous Detonation Waves

    OpenAIRE

    Borisov, A.; Mel'Nichuk, O.; Kasimov, A.; Khasainov, B.; Troshin, K.; Kosenkov, V.

    1995-01-01

    There is a definite inconsistency between the classical ZND theory of detonation and contemporary experimental observations and attempts to model real detonation waves. Nevertheless, the classical onedimensional model of detonation is still extensively used in interpreting measurements because of its simplicity and physical clarity. This naturally raises the questions, what does actually the classical model represent and how one can relate the real multidimensional wave structure to an effect...

  5. Laser driven detonation waves above a solid target

    International Nuclear Information System (INIS)

    The interaction of a TEA CO2 laser pulse with a carbon target in an argon atmosphere (p approximately mmHg) is shown to produce a double detonation wave system. The laser driven detonation wave becomes the most important as the gas pressure is increased. Calculation of the energy in the detonation waves is in good agreement with the incident laser energy at different times during the main laser pulse and the long tail. The observation of the incident laser detonation wave accounts for the anomalous energies reported previously. (Auth.)

  6. Benign Episodic Unilateral Mydriasis (Case Report

    Directory of Open Access Journals (Sweden)

    Eylem Değirmenci

    2012-09-01

    Full Text Available Benign episodic unilateral mydriasis is a descriptive situation with recurrent unilateral mydriasis in adult people especially women with migraine. A 20 year-old man who presented with paroxysmal left pupil mydriasis and diagnosed as benign episodic unilateral mydriasis after the examinations to exclude the other reasons of anisocoria was reported. In such cases to keep in mind the benign causes of mydriasis would be helpful to avoid unnecessary invasive tests.

  7. Benign Papules and Nodules of Oral Mucosa

    Directory of Open Access Journals (Sweden)

    Mehmet Salih Gürel

    2012-12-01

    Full Text Available This article reviews some of the more common benign oral papules and nodules of oral mucosa with emphasis on their etiology, epidemiology, clinical presentation, histopathology, and treatment. These lesions include mucocele, traumatic fibroma, epulis, pyogenic granuloma, oral papilloma, oral warts, lymphangioma, hemangioma, lipoma, oral nevi and some soft tissue benign tumors. These benign lesions must be separated clinically and histologically from precancerous and malign neoplastic lesions. Accurate clinico-pathological diagnosis is mandatory to insure appropriate therapy.

  8. Effect of Deflagration-to-Detonation Transition on Pulse Detonation Engine Impulse

    OpenAIRE

    Cooper, M.; S. Jackson; Shepherd, J. E.

    2000-01-01

    A detonation tube was built to study the deflagration-to-detonation transition (DDT) process and the impulse generated when combustion products exhaust into the atmosphere. The reactants used were stoichiometric ethylene and oxygen mixture with varying amounts of nitrogen present as diluent. The effects of varying the initial pressure from 30 kPa to 100 kPa were studied, as were the effects of varying the diluent concentration from 0% to 73.8% of the total mixture. Measurements were carried o...

  9. Performance characterization of swept ramp obstacle fields in pulse detonation applications

    OpenAIRE

    Dvorak, William T.

    2010-01-01

    Pulse Detonation technology offers the potential for substantial increases in thrust and fuel efficiency in subsonic and supersonic flight Mach ranges through the use of a detonative vs. deflagrative combustion process. One of the approaches to reliably obtain a fuel-air detonation is to accelerate a deflagration combustion wave to detonation through the use of turbulence devices, known as detonation-to-deflagration transition. Current geometries for deflagration-to-detonation transition sacr...

  10. Benign paroxysmal torticollis in infancy

    Directory of Open Access Journals (Sweden)

    Dimitrijević Lidija

    2006-01-01

    Full Text Available Background. Benign paroxysmal torticollis (BPT is an episodic functional disorder of unknown etiology, characterized by the periods of torticollic posturing of the head, that occurs in the early months of life in healthy children. Case report. We reported two patients with BPT. In the first patient the symptoms were observed at the age of day 20, and disappeared at the age of 3 years. There were 10 episodes, of which 2 were followed by vomiting, pallor, irritability and the abnormal trunk posture. In the second patient, a 12-month-old girl, BPT started from day 15. She had 4 episodes followed by vomiting in the first year. Both girls had the normal psychomotor development. All diagnostical tests were normal. Conclusion. The recognition of BPT, as well as its clinical course may help to avoid not only unnecessary tests and the treatment, but also the anxiety of the parents.

  11. Management of Benign Prostatic Hyperplasia.

    Science.gov (United States)

    Kim, Eric H; Larson, Jeffrey A; Andriole, Gerald L

    2016-01-01

    Benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms (LUTS) commonly affect older men. Age-related changes associated with metabolic disturbances, changes in hormone balance, and chronic inflammation may cause BPH development. The diagnosis of BPH hinges on a thorough medical history and focused physical examination, with attention to other conditions that may be causing LUTS. Digital rectal examination and urinalysis should be performed. Other testing may be considered depending on presentation of symptoms, including prostate-specific antigen, serum creatinine, urine cytology, imaging, cystourethroscopy, post-void residual, and pressure-flow studies. Many medical and surgical treatment options exist. Surgery should be reserved for patients who either have failed medical management or have complications from BPH, such as recurrent urinary tract infections, refractory urinary retention, bladder stones, or renal insufficiency as a result of obstructive uropathy. PMID:26331999

  12. Undetected Aorto-RV Fistula With Aortic Valve Injury and Delayed Cardiac Tamponade following a Chest Stab Wound: A Case Report

    Directory of Open Access Journals (Sweden)

    Jamil Esfahanizadeh

    2013-06-01

    Full Text Available Introduction: Although a few patients will survive after penetrating cardiac injuries, some of them may have unnoticeable intracardiac injuries. The combination of aorto-right ventricular fistula with aortic valve injury is rare.Case Presentation: A 19 year-old man referred with an aorto-right ventricular fistula accompanied with aortic regurgitation and delayed tamponade following a stab in the chest. The patient was scheduled for fistula repair, aortic valve replacement and pericardectomy two months after trauma.Conclusions: To prevent missing intracardiac injury and also late cardiac injury complications, in all pericordial stab wounds, serial clinical examinations and serial echocardiography should be performed. In addition, cardiac injuries should be repaired during the same hospital stay.

  13. Predicting polarization signatures for double-detonation and delayed-detonation models of Type Ia supernovae

    CERN Document Server

    Bulla, M; Kromer, M; Seitenzahl, I R; Fink, M; Ciaraldi-Schoolmann, F; Roepke, F K; Hillebrandt, W; Pakmor, R; Ruiter, A J; Taubenberger, S

    2016-01-01

    Calculations of synthetic spectropolarimetry are one means to test multi-dimensional explosion models for Type Ia supernovae. In a recent paper, we demonstrated that the violent merger of a 1.1 and 0.9 M$_{\\odot}$ white dwarf binary system is too asymmetric to explain the low polarization levels commonly observed in normal Type Ia supernovae. Here, we present polarization simulations for two alternative scenarios: the sub-Chandrasekhar mass double-detonation and the Chandrasekhar mass delayed-detonation model. Specifically, we study a two-dimensional double-detonation model and a three-dimensional delayed-detonation model, and calculate polarization spectra for multiple observer orientations in both cases. We find modest polarization levels ($<$ 1 per cent) for both explosion models. Polarization in the continuum peaks at $\\sim$ 0.1$-$0.3 per cent and decreases after maximum light, in excellent agreement with spectropolarimetric data of normal Type Ia supernovae. Higher degrees of polarization are found ac...

  14. Benign paroxysmal positional vertigo in Parkinson's disease

    NARCIS (Netherlands)

    Wensen, E. van; Leeuwen, R.B. van; Zaag-Loonen, H.J. van der; Masius-Olthof, S.; Bloem, B.R.

    2013-01-01

    BACKGROUND: Dizziness is a frequent complaint of patients with Parkinson's disease (PD), and orthostatic hypotension (OH) is often thought to be the cause. We studied whether benign paroxysmal positional vertigo (BPPV) could also be an explanation. AIM: To assess the prevalence of benign paroxysmal

  15. Deflagration to detonation transition in thermonuclear supernovae

    International Nuclear Information System (INIS)

    Type Ia supernovae are an important tool to determine the expansion history of our Universe. Thus, considerable attention has been given to both observations and models of these events. The most popular explosion model is the central ignition of a deflagration in the dense C+O interior of a Chandrasekhar mass white dwarf, followed by a transition to a detonation (TDD). We study in this thesis a new mechanism for this transition. The most robust and studied progenitor model and the postulated mechanism for the TDD, the so called 'Zel'dovich gradient mechanism', are presented. State of the art 3D simulations of such a delayed detonation, at the price of some adjustments, can indeed reproduce observables. But due to largely unresolved physical scales, such simulations cannot explain the TDD by themselves, and especially, the physical mechanism which triggers this transition - which is not yet understood, even on Earth, for unconfined media. It is then discussed why the current Zel'dovich mechanism might be too constraining for a SN Ia model, pointing to a new approach, which is the core result of this thesis.In the final part, our alternative model for DDT in supernovae, the acoustic heating of the pre-supernova envelope, is presented. A planar model first proves that small amplitude acoustic perturbations (generated by a turbulent flame) are actually amplified in a steep density gradient, up to a point where they turn into shocks able to trigger a detonation. Then, this mechanism is applied to more realistic models, taking into account, in spherical geometry, the expanding envelope. A parametric study demonstrates the validity of the model for a reasonable range of acoustic wave amplitudes and frequencies.To conclude, some exploratory 2D and 3D MHD simulations, seeking for realistic acoustic source compatible with our mechanism, are presented. (author)

  16. Comparison Of Flat-Knitted Structures Made Of Poly(P-Phenylene-2,6-Benzobisoxazole) And Para-Aramid Referring To Their Stab Resistance

    Science.gov (United States)

    Obermann, M.; Aumann, S.; Heimlich, F.; Weber, M. O.; Schwarz-Pfeiffer, A.

    2016-07-01

    In the field of protective gear, developers always aim for lighter and more flexible material in order to increase the wearing comfort. Suppliers now work on knitted garments in the sports-sector as well as in workwear and protective gear for policemen or security-agents. In a recent project different knitted structures made of a poly(p-phenylene-2,6-benzobisoxazole) (PBO)-multifilament were compared to their counterparts made of para-aramid. In focus of the comparison stood the stab-resistance linked to either the mass per unit area or the stitch density. The tested fabrics were produced on hand flat knitting machines as well as on electronical flat knitting machines of the type Stoll CMS 330TC4, in order to analyse fabrics with different tightness factor and machine gauges. The stab resistance of the different knitted fabrics was examined according to the standard of the Association of Test Laboratories for Bullet, Stab or Pike Resistant Materials and Construction Standards. The presentation includes the depiction of the results of the test series and their interpretation. Furthermore it will give an outlook on most suitable combinations of materials and structures to be used in protective gear.

  17. A note on the detonation of TNT

    Directory of Open Access Journals (Sweden)

    M. P. Murgai

    1953-01-01

    Full Text Available Whenever a non-reactive shock passes .through a system which is capable of undergoing an exothermic reaction, the high temperature and pressure in the shock front may start the chemical reaction, and it is possible that the heat evolved, under suitable conditions, map support the wave, and a self sustained stable shock propagate through the system. This shock wave maintained by the heat of the reaction constitutes a stable detonation wave. The equations of conservation of mass, momentum and energy, across the wave give the well known Rankine Huginiot equation. The formulation of an equation of state leaves the conditions behind the pure shook wave undetermined

  18. Progress of continuously rotating detonation engines

    Directory of Open Access Journals (Sweden)

    Zhou Rui

    2016-02-01

    Full Text Available Continuously rotating detonation engine (CRDE is a focus for concern in the field of aerospace propulsion. It has several advantages, including one-initiation, high thermal efficiency and simple structure. Due to these characteristics, it is expected to bring revolutionary advancements to aviation and aerospace propulsion systems and now has drawn much attention throughout the world. In this paper, an overview of the development of CRDE is given from several aspects: basic concepts, applications, experimental studies, numerical simulations, and so on. Representative results and outstanding contributions are summarized and the unresolved issues for further engineering applications of CRDE are provided.

  19. Single and multiple detonations in white dwarfs

    OpenAIRE

    García Senz, Domingo; Bravo Guil, Eduardo; Woosley, S.

    1999-01-01

    A currently favored model for Type Ia supernovae consists of a carbon-oxygen (CO) white dwarf ( 0.6–1.0 M), surrounded by a thick layer of helium ( 0.2–0.3 M), which explodes as a consequence of successive detonations in the helium layer and the CO core. Previous studies, carried out in one and two dimensions, have shown that this model is capable of providing light curves and late-time spectra in agreement with observations, though the peak light spectrum may be problematic. These same studi...

  20. Shock-to-Detonation Transition simulations

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-07-14

    Shock-to-detonation transition (SDT) experiments with embedded velocity gauges provide data that can be used for both calibration and validation of high explosive (HE) burn models. Typically, a series of experiments is performed for each HE in which the initial shock pressure is varied. Here we describe a methodology for automating a series of SDT simulations and comparing numerical tracer particle velocities with the experimental gauge data. Illustrative examples are shown for PBX 9502 using the HE models implemented in the xRage ASC code at LANL.

  1. Surface pressures from laser-supported detonations

    International Nuclear Information System (INIS)

    The surface pressures directly behind a Laser-Supported Detonation (LSD) were measured with a system of carbon piezoresistive gauges. A quartz piezoelectric gauge was also used to measure surface pressures far away from the laser spot. The small size of the carbon gauges, relative to the laser beam diameter, permitted simultaneous resolution of the surface pressure history at several locations within the laser spot. A comparison of the experimental data with recent theories indicates that the theories predict peak pressures close to those measured but overestimate the impulse intensity at the target surface

  2. DDT and detonation waves in dust-air mixtures

    Science.gov (United States)

    Zhang, F.; Grönig, H.; van de Ven, A.

    This paper summarizes the studies of DDT and stable detonation waves in dust-air mixtures at the Stosswellenlabor of RWTH Aachen. The DDT process and propagation mechanism for stable heterogeneous dust detonations in air are essentially the same as in the oxygen environment studied previously. The dust DDT process in tubes is composed of a reaction compression stage followed by a reaction shock stage as the pre-detonation process. The transverse waves that couple the shock wave and the chemical energy release are responsible for the propagation of a stable dust-air detonation. However, the transverse wave spacing of dust-air mixtures is much larger. Therefore, DDT and propagation of a stable detonation in most industrial and agricultural, combustible dust-air mixtures require a tube that has a large diameter between 0.1 m and 1 m and a sufficient length-diameter ratio beyond 100, when an appropriately strong initiation energy is used. Two dust detonation tubes, 0.14 m and 0.3 m in diameter, were used for observation of the above-mentioned results in cornstarch, anthraquinone and aluminum dust suspended in air. Smoked-foil technique was also used to measure the cellular structure of dust detonations in the 0.3 m detonation tube.

  3. Gas-phase detonation propagation in mixture composition gradients.

    Science.gov (United States)

    Kessler, D A; Gamezo, V N; Oran, E S

    2012-02-13

    The propagation of detonations through several fuel-air mixtures with spatially varying fuel concentrations is examined numerically. The detonations propagate through two-dimensional channels, inside of which the gradient of mixture composition is oriented normal to the direction of propagation. The simulations are performed using a two-component, single-step reaction model calibrated so that one-dimensional detonation properties of model low- and high-activation-energy mixtures are similar to those observed in a typical hydrocarbon-air mixture. In the low-activation-energy mixture, the reaction zone structure is complex, consisting of curved fuel-lean and fuel-rich detonations near the line of stoichiometry that transition to decoupled shocks and turbulent deflagrations near the channel walls where the mixture is extremely fuel-lean or fuel-rich. Reactants that are not consumed by the leading detonation combine downstream and burn in a diffusion flame. Detonation cells produced by the unstable reaction front vary in size across the channel, growing larger away from the line of stoichiometry. As the size of the channel decreases relative to the size of a detonation cell, the effect of the mixture composition gradient is lessened and cells of similar sizes form. In the high-activation-energy mixture, detonations propagate more slowly as the magnitude of the mixture composition gradient is increased and can be quenched in a large enough gradient. PMID:22213660

  4. Modelling of detonation cellular structure in aluminium suspensions

    Science.gov (United States)

    Briand, A.; Veyssiere, B.; Khasainov, B. A.

    2010-12-01

    Heterogeneous detonations involving aluminium suspensions have been studied for many years for industrial safety policies, and for military and propulsion applications. Owing to their weak detonability and to the lack of available experimental results on the detonation cellular structure, numerical simulations provide a convenient way to improve the knowledge of such detonations. One major difficulty arising in numerical study of heterogeneous detonations involving suspensions of aluminium particles in oxidizing atmospheres is the modelling of aluminium combustion. Our previous two-step model provided results on the effect on the detonation cellular structure of particle diameter and characteristic chemical lengths. In this study, a hybrid model is incorporated in the numerical code EFAE, combining both kinetic and diffusion regimes in parallel. This more realistic model provides good agreement with the previous two-step model and confirms the correlations found between the detonation cell width, and particle diameter and characteristic lengths. Moreover, the linear dependence found between the detonation cell width and the induction length remains valid with the hybrid model.

  5. Detonator using Nickel Hydrazine Nitrate as Primary Explosive

    Directory of Open Access Journals (Sweden)

    B. Hariharanath

    2006-07-01

    Full Text Available Nickel hydrazine nitrate is an energetic coordination compound having explosiveproperties in between that of primary and secondary. This compound was used to develop a newtype of detonator by replacing the sensitive primary explosive, lead azide in conventionaldetonators and keeping RDX (cyclotrimethylenetrinitramine as the output secondary explosive.The detonator consists of three regions, viz., initiation, deflagration-to-detonation transition(DDT, and output. The initiation and the electrical rating of 1A/1W no-fire were achieved usinga suitable squib. The DDT and the output were taken care of, by pressing requisite quantitiesof Nickel hydrazine nitrate and RDX, respectively at required densities in a stainless steel stemchannel. The detonator assembly involves crimping the squib and the stem channel in a stainlesssteel housing and applying a suitable resin at the crimped-end for leak tightness. The outputwas assessed from the dent depth on aluminium plate, volume expansion on lead block, and byachieving veloctiy of detonation of 8200 m/s in mild detonating cords, containing 0.95 g/m ofRDX, which indicates full-order detonation. The detonators were tested at system level andfound to perform satisfactorily.

  6. Half-Cell Law of Regular Cellular Detonations

    Institute of Scientific and Technical Information of China (English)

    WANG Chun; JIANG Zong-Lin; GAO Yun-Liang

    2008-01-01

    Numerical simulations illustrate the half-cell law of regular cellular detonations propagating in confined space,i.e., the number of cells always maintains an integral multiple of half cell. The cells adapt themselves larger or smaller to the size of the unconfined space by maintaining the cell scale larger or smaller than the original cells of detonation.

  7. Porosity of detonation coatings on the base of chromium carbide

    International Nuclear Information System (INIS)

    Porosity of detonation coatings on the base of chromium carbide is estimated by the hydrostatic weighing. The open porosity value dependence on the distance of spraying, depth of the charge, ratio and volume of the detonator barrie filing with gas components is established. Pore distribution in the cross section of a specimen tested for porosity is studied by the methods of metallographic analysis

  8. MRI appearances of benign uterine disease

    International Nuclear Information System (INIS)

    Benign uterine disease is a common entity affecting women of all ages. Ultrasound has historically been the predominant imaging method used in the evaluation of benign gynaecological disease, magnetic resonance imaging (MRI) being reserved for use in the staging of malignant uterine and cervical disease. MRI is now increasingly used in the diagnosis of benign uterine disease as well as a tool for problem-solving in cases of diagnostic dilemma. It allows detailed assessment of benign conditions, such as endometrial lesions, leiomyomas, and adenomyosis, and can be helpful in the stratification of patients to different treatment modalities, including surgical resection, uterine artery embolization, and medical therapies. In this article, we review the MRI findings in the common benign uterine diseases

  9. Measuring In-Situ Mdf Velocity Of Detonation

    Science.gov (United States)

    Horine, Frank M.; James, Jr., Forrest B.

    2005-10-25

    A system for determining the velocity of detonation of a mild detonation fuse mounted on the surface of a device includes placing the device in a predetermined position with respect to an apparatus that carries a couple of sensors that sense the passage of a detonation wave at first and second spaced locations along the fuse. The sensors operate a timer and the time and distance between the locations is used to determine the velocity of detonation. The sensors are preferably electrical contacts that are held spaced from but close to the fuse such that expansion of the fuse caused by detonation causes the fuse to touch the contact, causing an electrical signal to actuate the timer.

  10. Numerical investigation on evolution of cylindrical cellular detonation

    Institute of Scientific and Technical Information of China (English)

    WANG Chun; JIANG Zong-lin; HU Zong-min; HAN Gui-lai

    2008-01-01

    Cylindrical cellular detonation is numerically investigated by solving twodimensional reactive Euler equations with a finite volume method on a two-dimensional self-adaptive unstructured mesh.The one-step reversible chemical reaction model is applied to simplify the control parameters of chemical reaction.Numerical results demonstrate the evolution of cellular cell splitting of cylindrical cellular detonation explored in experimentas.Split of cellular structures shows different features in the near-field and far-field from the initiation zone.Variation of the local curvature is a key factor in the behavior of cell split of cylindrical cellular detonation in propagation.Numerical results show that split of cellular structures comes from the self-organization of transverse waves corresponding to the development of small disturbances along the detonation front related to detonation instability.

  11. A thermodynamic approach for identifying the conditions for gasless detonation

    Energy Technology Data Exchange (ETDEWEB)

    Gheribi, Aïmen E., E-mail: aimen.gheribi@polymtl.ca [Center for Research in Computational Thermochemistry, Department of Chemical Eng., École Polytechnique de Montréal, QC (Canada); Lee, Julian J. [Defence Research and Development Canada – Suffield, Suffield, AB (Canada); Thibault, Paul [TimeScales Scientific Ltd., Medicine Hat, AB (Canada)

    2015-01-15

    The present paper describes a theoretical method of examining thermodynamic equilibrium detonation states for reactions producing little or no gaseous products. Calculation of Phase Diagram (CALPHAD) techniques are used to calculate the thermodynamic states of the condensed-phase reaction at ambient conditions, and an analytical shock physics approach is used to estimate the detonation state. This method provides more accurate thermo–chemical equilibrium calculations for low-gas reactive mixtures, and can help evaluate the ability of a mixture to support a gasless detonation. A representative analysis was performed on an iron–aluminum thermite mixture and significant differences were found compared to previously published results. - Highlights: • A new CALPHAD method is used to identify optimal condition for gasless detonation. • The FactSage software and databases are used to calculate the materials properties. • The optimal detonation compositions are presented and discussed.

  12. Effect of prill structure on detonation performance of ANFO

    Energy Technology Data Exchange (ETDEWEB)

    Salyer, Terry R [Los Alamos National Laboratory; Short, Mark [Los Alamos National Laboratory; Kiyanda, Charles B [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory; Zimmerly, Tony [EMRTC NMT

    2010-01-01

    While the effects of charge diameter, fuel mix ratio, and temperature on ANFO detonation performance are substantial, the effects of prill type are considerable as well as tailorable. Engineered AN prills provide a means to improve overall performance, primarily by changing the material microstructure through the addition of features designed to enhance hot spot action. To examine the effects of prill type (along with fuel mix ratio and charge diameter) on detonation performance, a series of precision, large-scale, ANFO front-curvature rate-stick tests was performed. Each shot used standard No. 2 diesel for the fuel oil and was essentially unconfined with cardboard confinement. Detonation velocities and front curvatures were measured while actively maintaining consistent shot temperatures. Based on the experimental results, DSD calibrations were performed to model the detonation performance over a range of conditions, and the overall effects of prill microstructure were examined and correlated with detonation performance.

  13. Atomistic simulation of detonation initiation by ultra-short impact

    Science.gov (United States)

    Murzov, S. A.; Zhakhovsky, V. V.

    2015-11-01

    We present results of the classical molecular dynamics simulation of detonation initiation in simple AB model of a high explosive compressed by ultra-short shock wave (SW). The simplified reactive empirical bond order potential (REBO) defines interatomic forces in the AB model explosive made up of diatomic AB molecules. Simulation of ultra-short piston-driven compression of AB explosive with duration of picoseconds represents an indirect initiation via a thin metal foil irradiated by a femtosecond laser pulse. We studied transition of SW to a detonation wave (DW), including evolution of calculated pressure profile in a sample. A run distance to detonation of such AB explosive film, which is required for detonation initiation, was obtained. Variation of loading time and piston velocity gives a 2D region of transition from SW to DW. The influence of pores on detonation initiation threshold is discussed.

  14. Light detonation wave in a cylindrical Z-pinch

    Science.gov (United States)

    Yusupaliev, U.; Sysoev, N. N.; Shuteev, S. A.; Elenskii, V. G.

    2015-09-01

    A secondary compression wave previously observed by other researchers in a cylindrical Z-pinch has been identified in this work as a light detonation wave. It appears on the inner surface of a discharge chamber under the action of the intense ultraviolet radiation from a plasma pinch at the stage of its maximum compression. The condition of the light detonation wave has been determined experimentally. The dependence of its Mach number on a generalized dimensionless variable has been determined taking into account the conservation laws for the light detonation wave including the pressure of the gas, expenses on the formation of the surface plasma, and the energy of ionization of the gas involved in the wave. An analogy with the laser-supported detonation wave created by intense laser radiation has been revealed. The indicated dependence is within the error of measurement in agreement with the experimental data for light detonation waves created by both methods.

  15. The direct cost of traumatic secretion transfer in hermaphroditic land snails: individuals stabbed with a love dart decrease lifetime fecundity.

    Science.gov (United States)

    Kimura, Kazuki; Chiba, Satoshi

    2015-04-01

    Several taxa of simultaneously hermaphroditic land snails exhibit a conspicuous mating behaviour, the so-called shooting of love darts. During mating, such land snail species transfer a specific secretion by stabbing a mating partner's body with the love dart. It has been shown that sperm donors benefit from this traumatic secretion transfer, because the secretions manipulate the physiology of a sperm recipient and increase the donors' fertilization success. However, it is unclear whether reception of dart shooting is costly to the recipients. Therefore, the effect of sexual conflict and antagonistic arms races on the evolution of traumatic secretion transfer in land snails is still controversial. To examine this effect, we compared lifetime fecundity and longevity between the individuals that received and did not receive dart shooting from mating partners in Bradybaena pellucida. Our experiments showed that the dart-receiving snails suffered reduction in lifetime fecundity and longevity. These results suggest that the costly mating behaviour, dart shooting, generates conflict between sperm donors and recipients and that sexually antagonistic arms races have contributed to the diversification of the morphological and behavioural traits relevant to dart shooting. Our findings also support theories suggesting a violent escalation of sexual conflict in hermaphroditic animals. PMID:25761713

  16. Detonation characteristics of dimethyl ether and ethanol-air mixtures

    Science.gov (United States)

    Diakow, P.; Cross, M.; Ciccarelli, G.

    2015-05-01

    The detonation cell structure in dimethyl ether vapor and ethanol vapor-air mixtures was measured at atmospheric pressure and initial temperatures in the range of 293-373 K. Tests were carried out in a 6.2-m-long, 10-cm inner diameter tube. For more reactive mixtures, a series of orifice plates were used to promote deflagration-to-detonation transition in the first half of the tube. For less reactive mixtures prompt detonation initiation was achieved with an acetylene-oxygen driver. The soot foil technique was used to capture the detonation cell structure. The measured cell size was compared to the calculated one-dimensional detonation reaction zone length. For fuel-rich dimethyl ether mixtures the calculated reaction zone is highlighted by a temperature gradient profile with two maxima, i.e., double heat release. The detonation cell structure was interpreted as having two characteristic sizes over the full range of mixture compositions. For mixtures at the detonation propagation limits the large cellular structure approached a single-head spin, and the smaller cells approached the size of the tube diameter. There is little evidence to support the idea that the two cell sizes observed on the foils are related to the double heat release predicted for the rich mixtures. There was very little influence of initial temperature on the cell size over the temperature range investigated. A double heat release zone was not predicted for ethanol-air detonations. The detonation cell size for stoichiometric ethanol-air was found to be similar to the size of the small cells for dimethyl ether. The measured cell size for ethanol-air did not vary much with composition in the range of 30-40 mm. For mixtures near stoichiometric it was difficult to discern multiple cell sizes. However, near the detonation limits there was strong evidence of a larger cell structure similar to that observed in dimethyl ether air mixtures.

  17. On the influence of low initial pressure and detonation stochastic nature on Mach reflection of gaseous detonation waves

    Science.gov (United States)

    Wang, C. J.; Guo, C. M.

    2014-09-01

    The two-dimensional, time-dependent and reactive Navier-Stokes equations were solved to obtain an insight into Mach reflection of gaseous detonation in a stoichiometric hydrogen-oxygen mixture diluted by 25 % argon. This mixture generates a mode-7 detonation wave under an initial pressure of 8.00 kPa. Chemical kinetics was simulated by an eight-species, forty-eight-reaction mechanism. It was found that a Mach reflection mode always occurs for a planar detonation wave or planar air shock wave sweeping over wedges with apex angles ranging from to . However, for cellular detonation waves, regular reflection always occurs first, which then transforms into Mach reflection. This phenomenon is more evident for detonations ignited under low initial pressure. Low initial pressure may lead to a curved wave front, that determines the reflection mode. The stochastic nature of boundary shape and transition distance, during deflagration-to-detonation transition, leads to relative disorder of detonation cell location and cell shape. Consequently, when a detonation wave hits the wedge apex, there appears a stochastic variation of triple point origin and variation of the angle between the triple point trajectory and the wedge surface. As the wedge apex angle increases, the distance between the triple point trajectory origin and the wedge apex increases, and the angle between the triple point trajectory and the wedge surface decreases exponentially.

  18. Nocturia and benign prostatic hyperplasia

    Directory of Open Access Journals (Sweden)

    Laketić Darko

    2008-01-01

    Full Text Available Background/Aim. Nocturia often occurs in patients with benign prostate hyperplasia (BPH. The aim of the study was to investigate the frequency of nocturia in patients with BPH. Nocturia and other factors associated with it were also investigated. Methods. Forty patients with the confirmed diagnosis of BPH were studied. Transurethral and transvesical prostatectomy were performed in all the patients. Symptoms were evaluated with the International Prostate Symptom Score before, as well as three and six months after the surgery. All the results were compared with the control group. Results. There was no statistically significant difference between the patients before and after the surgery regarding nocturia. There was, however, a statistically significant difference between the operated patients and the control group regarding nocturia, as well as a statistically significant correlation between noctruia and the age of the patients in both the investigated and the control group. A correlation also existed between nocturia and the prostatic size. Conclusion. There was no statistically significant improvement in symptoms of nocturia after the surgery. It is necessary to be very careful in decision making in patients with nonabsolute indiction for surgery and isolated bothersome symptom of nocturia. Age of a patient should also be considered in the evaluation of favorable result of the surgery because of a significant correlation between noctura and the age of a patient.

  19. Thermonuclear detonations ensuing white dwarf mergers

    CERN Document Server

    Dan, Marius; Brüggen, Marcus; Ramirez-Ruiz, Enrico; Rosswog, Stephan

    2015-01-01

    The merger of two white dwarfs (WDs) has for many years not been considered as the favoured model for the progenitor system of type Ia supernovae (SNe Ia). But recent years have seen a change of opinion as a number of studies, both observational and theoretical, have concluded that they should contribute significantly to the observed type Ia supernova rate. In this paper, we study the ignition and propagation of detonation through post-merger remnants and we follow the resulting nucleosynthesis up to the point where a homologous expansion is reached. In our study we cover the entire range of WD masses and compositions. For the emergence of a detonation we study several setups, guided by both merger remnants from our own simulations and by results taken from the literature. We carefully compare the nucleosynthetic yields of successful explosions with SN Ia observations. Only three of our models are consistent with all the imposed constraints and potentially lead to a standard type Ia event. The first one, a $0...

  20. Numerical solution of under-resolved detonations

    Science.gov (United States)

    Tosatto, Luca; Vigevano, Luigi

    2008-02-01

    A new fractional-step method is proposed for the numerical solution of high speed reacting flows, where the chemical time scales are often much smaller than the fluid dynamical time scales. When the problem is stiff, because of insufficient spatial/temporal resolution, a well-known spurious numerical phenomenon occurs in standard finite volume schemes: the incorrect calculation of the speed of propagation of discontinuities. The new method is first illustrated considering a one-dimensional scalar hyperbolic advection/reaction equation with stiff source term, which may be considered as a model problem to under-resolved detonations. During the reaction step, the proposed scheme replaces the cell average representation with a two-value reconstruction, which allows us to locate the discontinuity position inside the cell during the computation of the source term. This results in the correct propagation of discontinuities even in the stiff case. The method is proved to be second-order accurate for smooth solutions of scalar equations and is applied successfully to the solution of the one-dimensional reactive Euler equations for Chapman-Jouguet detonations.

  1. Detonations in white dwarf dynamical interactions

    CERN Document Server

    Aznar-Siguán, Gabriela; Lorén-Aguilar, Pablo; José, Jordi; Isern, Jordi

    2013-01-01

    In old, dense stellar systems collisions of white dwarfs are a rather frequent phenomenon. Here we present the results of a comprehensive set of Smoothed Particle Hydrodynamics simulations of close encounters of white dwarfs aimed to explore the outcome of the interaction and the nature of the final remnants for different initial conditions. Depending on the initial conditions and the white dwarf masses, three different outcomes are possible. Specifically, the outcome of the interaction can be either a direct or a lateral collision or the interaction can result in the formation of an eccentric binary system. In those cases in which a collision occurs, the infalling material is compressed and heated such that the physical conditions for a detonation may be reached during the most violent phases of the merger. While we find that detonations occur in a significant number of our simulations, in some of them the temperature increase in the shocked region rapidly lifts degeneracy, leading to the quenching of the bu...

  2. Pulse Detonation Rocket MHD Power Experiment

    Science.gov (United States)

    Litchford, Ron J.; Cook, Stephen (Technical Monitor)

    2002-01-01

    A pulse detonation research engine (MSFC (Marshall Space Flight Center) Model PDRE (Pulse Detonation Rocket Engine) G-2) has been developed for the purpose of examining integrated propulsion and magnetohydrodynamic power generation applications. The engine is based on a rectangular cross-section tube coupled to a converging-diverging nozzle, which is in turn attached to a segmented Faraday channel. As part of the shakedown testing activity, the pressure wave was interrogated along the length of the engine while running on hydrogen/oxygen propellants. Rapid transition to detonation wave propagation was insured through the use of a short Schelkin spiral near the head of the engine. The measured detonation wave velocities were in excess of 2500 m/s in agreement with the theoretical C-J velocity. The engine was first tested in a straight tube configuration without a nozzle, and the time resolved thrust was measured simultaneously with the head-end pressure. Similar measurements were made with the converging-diverging nozzle attached. The time correlation of the thrust and head-end pressure data was found to be excellent. The major purpose of the converging-diverging nozzle was to configure the engine for driving an MHD generator for the direct production of electrical power. Additional tests were therefore necessary in which seed (cesium-hydroxide dissolved in methanol) was directly injected into the engine as a spray. The exhaust plume was then interrogated with a microwave interferometer in an attempt to characterize the plasma conditions, and emission spectroscopy measurements were also acquired. Data reduction efforts indicate that the plasma exhaust is very highly ionized, although there is some uncertainty at this time as to the relative abundance of negative OH ions. The emission spectroscopy data provided some indication of the species in the exhaust as well as a measurement of temperature. A 24-electrode-pair segmented Faraday channel and 0.6 Tesla permanent

  3. 33 CFR 154.822 - Detonation arresters, flame arresters, and flame screens.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Detonation arresters, flame... BULK Vapor Control Systems § 154.822 Detonation arresters, flame arresters, and flame screens. (a) Each detonation arrester required by this part must: (1) Be capable of arresting a detonation from either side...

  4. The stabbing of Amelia (or how was extinguished the married women discrimination from the argentinian telephone service

    Directory of Open Access Journals (Sweden)

    Dora Barrancos

    2008-04-01

    Full Text Available This paper highlights the tracks of Amelia C. Her life story as switchboard is relevant to understand the women' s discrimination in laboral market in the early twentieth century. This article will be focused on the marital satatus as pattern of female exclusion. The strategy used by Amelia against that pattern, although individual and even desperate, detonated a series of revisions of existing legislation that were supported by different groups in society. The corpus is based on records of the telephone company in which Amelia was employed for several years and the impact of their strategies in the local press.

  5. Detonation propagation in narrow gaps with various configurations

    Science.gov (United States)

    Monwar, M.; Yamamoto, Y.; Ishii, K.; Tsuboi, T.

    2007-08-01

    In general all detonation waves have cellular structure formed by the trajectory of the triple points. This paper aims to investigate experimentally the propagation of detonation in narrow gaps for hydrogen-oxygen-argon mixtures in terms of various gap heights and gap widths. The gap of total length 1500 mm was constructed by three pair of stainless plates, each of them was 500 mm in length, which were inserted in a detonation tube. The gap heights were varied from 1.2 mm to 3.0 mm while the gap widths were varied from 10 mm to 40 mm. Various argon dilution rates were tested in the present experiments to change the size of cellular structure. Attempts have been made by means of reaction front velocity, shock front velocity, and smoked foil to record variations of cellular structure inside the gaps. A combination probe composed of a pressure and an ion probe detected the arrival of the shock and the reaction front individually at one measurement point. Experimental results show that the number of the triple points contained in detonation front decreases with decrease in the gap heights and gap widths, which lead to larger cellular structures. For mixtures with low detonability, cell size is affected by a certain gap width although conversely cell size is almost independent of gap width. From the present result it was found that detonation propagation inside the gaps is strongly governed by the gap height and effects of gap width is dependent on detonability of mixtures.

  6. Development of a chemical microthruster based on pulsed detonation

    International Nuclear Information System (INIS)

    The development of a microthruster based on gaseous pulsed detonation is presented in this study. The feasibility of cyclic valveless pulsed detonation at frequencies over 100 Hz is first experimentally investigated in a microchannel with 1 mm × 0.6 mm rectangular cross-section. Highly reactive ethylene/oxygen mixtures are utilized to reduce the time and distance required for the reaction wave to run up to detonation in a smooth channel. High-speed visualizations have shown that the reaction waves reach detonative state through highly repeatable flame acceleration and deflagration-to-detonation transition processes in the channel. The validated concepts are implemented for the development of an integrated pulsed detonation microthruster. The microthruster was fabricated using low temperature co-fired ceramic tape technology. The volume of the reaction channel in the microthruster was 58 mm3. Spark electrodes and ion probes were embedded in the ceramic microthruster. The channel and via holes were fabricated using laser cutting techniques. Ion probe measurements showed that the reaction wave propagated at velocities larger than 2000 m s−1 before reaching the channel exit. The pulsed detonation microthruster has been successfully operated at frequencies as high as 200 Hz. (paper)

  7. Asbestos-related benign pleural disease review

    International Nuclear Information System (INIS)

    Benign pleural disease is the commonest manifestation of asbestos exposure encountered by radiologists. Benign pleural thickening can appear as circumscribed parietal pleural plaques or as more diffuse thickening of the visceral pleura. Benign-asbestos induced pleural effusions are a significant and under-recognized manifestation of asbestos exposure with important sequelae, such as diffuse pleural thickening which may be associated with functional impairment and for which compensation may be sought. This review concentrates on the strengths and weaknesses of chest radiography and computed tomography for the detection and characterization of benign asbestos-related pleural disease and the relevance of imaging abnormalities to compensation and functional impairment. Peacock, C. (2000). Clinical Radiology 55, 422-432

  8. Detonation re-initiation mechanism following the Mach reflection of a quenched detonation

    CERN Document Server

    Bhattacharjee, Rohit; Maines, Geoffrey; Maley, Logan; Radulescu, Matei Ioan

    2012-01-01

    This experimental study addresses the re-initiation mechanism of detonation waves following the Mach reflection of a shock-flame complex. The detonation diffraction around a cylinder is used to reproducibly generate the shock-flame complex of interest. The experiments are performed in methane-oxygen. We use a novel experimental technique of coupling a two-in-line-spark flash system with a double-frame camera in order to obtain microsecond time resolution permitting accurate schlieren velocimetry. The first series of experiments compares the non-reactive sequence of shock reflections with the reflection over a rough wall under identical conditions. It was found that the hot reaction products generated along the rough wall are entrained by the wall jet into a large vortex structure behind the Mach stem. The second series of experiments performed in more sensitive mixtures addressed the sequence of events leading to the detonation establishment along the Mach and transverse waves. Following ignition and jet entr...

  9. Cellular detonation diffraction in gas-particle mixtures

    Science.gov (United States)

    Fedorov, A. V.; Khmel, T. A.; Kratova, Y. V.

    2010-12-01

    Diffraction of cellular heterogeneous detonation out of a channel into open half-space in a mixture of aluminum particles and oxygen is investigated numerically. The flow is found to be very similar to gas detonation diffraction. The detonation weakening behind the step results in combustion front deceleration and decoupling from the leading shock wave. Subsequent re-initiation takes place in a transverse wave. New transverse waves are generated along the expanding front. The computations that were performed show that the critical number of cells is several times less than that for gases. This is confirmed by theoretical estimates based upon the Mitrofanov-Soloukhin approach.

  10. Geometry-specific scaling of detonation parameters from front curvature

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Scott I [Los Alamos National Laboratory; Short, Mark [Los Alamos National Laboratory

    2011-01-20

    It has previously been asserted that classical detonation curvature theory predicts that the critical diameter and the diameter-effect curve of a cylindrical high-explosive charge should scale with twice the thickness of an analogous two-dimensional explosive slab. The varied agreement of experimental results with this expectation have led some to question the ability of curvature-based concepts to predict detonation propagation in non-ideal explosives. This study addresses such claims by showing that the expected scaling relationship (hereafter referred to d = 2w) is not consistent with curvature-based Detonation Shock Dynamics (DSD) theory.

  11. The Physical Effects of Detonation in a Closed Cylindrical Chamber

    Science.gov (United States)

    Draper, C S

    1935-01-01

    Detonation in the internal-combustion engine is studied as a physical process. It is shown that detonation is accompanied by pressure waves within the cylinder charge. Sound theory is applied to the calculation of resonant pressure-wave frequencies. Apparatus is described for direct measurement of pressure-wave frequencies. Frequencies determined from two engines of different cylinder sizes are shown to agree with the values calculated from sound theory. An outline of the theoretically possible modes of vibration in a right circular cylinder with flat ends is included. An appendix by John P. Elting gives a method of calculating pressure in the sound wave following detonation.

  12. Numerical Modeling of Pulse Detonation Rocket Engine Gasdynamics and Performance

    Science.gov (United States)

    Morris, C. I.

    2003-01-01

    Pulse detonation engines (PDB) have generated considerable research interest in recent years as a chemical propulsion system potentially offering improved performance and reduced complexity compared to conventional gas turbines and rocket engines. The detonative mode of combustion employed by these devices offers a theoretical thermodynamic advantage over the constant-pressure deflagrative combustion mode used in conventional engines. However, the unsteady blowdown process intrinsic to all pulse detonation devices has made realistic estimates of the actual propulsive performance of PDES problematic. The recent review article by Kailasanath highlights some of the progress that has been made in comparing the available experimental measurements with analytical and numerical models.

  13. KIVA reactive hydrodynamics code applied to detonations in high vacuum

    Science.gov (United States)

    Greiner, N. Roy

    1989-08-01

    The KIVA reactive hydrodynamics code was adapted for modeling detonation hydrodynamics in a high vacuum. Adiabatic cooling rapidly freezes detonation reactions as a result of free expansion into the vacuum. After further expansion, a molecular beam of the products is admitted without disturbance into a drift tube, where the products are analyzed with a mass spectrometer. How the model is used for interpretation and design of experiments for detonation chemistry is explained. Modeling of experimental hydrodynamic characterization by laser-schlieren imaging and model-aided mapping that will link chemical composition data to particular volume elements in the explosive charge are also discussed.

  14. Some calculations of shocks and detonations for gas mixtures

    International Nuclear Information System (INIS)

    A computer code (CULDESAC) developed to model the flow of a mixture of two gases is reported. This is the first stage in the development of a code for modelling the detonation stage of vapour explosions. The equations governing this situation are described along with the numerical scheme developed to solve them. Calculations are presented for a steady-state shock, transient simulations of shock tubes (in one case containing different gases in each section) and detonations. It is concluded that the numerical scheme presented in the paper is suitable for the simulation of compressible flows encountered in the detonation stage of vapour explosions. (author)

  15. Oral benign fibrous histiocytoma: two case reports

    OpenAIRE

    Menditti, Dardo; Laino, Luigi; Mezzogiorno, Antonio; Sava, Sara; Bianchi, Alexander; Caruso, Giovanni; Di Maio, Luigi; Baldi, Alfonso

    2009-01-01

    Fibrous histiocytoma is a benign soft tissue tumour arising as a fibrous mass everywhere in the human body. The involvement of the oral cavity is rare. We report two cases of benign fibrous histiocytoma that localized in the oral cavity. The clinical and histological features of the lesion are reported. Finally, a literature revision of this pathology at the level of the oral cavity is reported.

  16. Current treatment of benign biliary strictures

    OpenAIRE

    Costamagna, Guido; Boškoski, Ivo

    2013-01-01

    Endoscopy is a widely used approach for the treatment of benign biliary strictures. Most common benign biliary strictures amandable to endoscopic treatment are post-cholecystectomy, dominant biliary strictures due to primary sclerosing cholangitis, biliary anastomotic strictures occurring after liver transplantation, and common bile duct strictures due to chronic pancreatitis. Surgery is a valid option in cases of complete transection or ligation of the common bile duct, in selected patients ...

  17. Benign Lesions of The Vocal Fold

    Directory of Open Access Journals (Sweden)

    Ozgur Surmelioglu

    2013-02-01

    Full Text Available Benign lesions of vocal folds are common disorders. Fifty percent of patients who have sound complaints are found to have these lesions after endoscopic and stroboscopic examinations. Benign vocal fold diseases are primarily caused by vibratory trauma. However they may also occur as a result of viral infections and congenital causes. These lesions are often presented with the complaints of dysphonia. [Archives Medical Review Journal 2013; 22(1.000: 86-95

  18. Computed tomographic findings of benign retroperitoneal tumors

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, Takashi; Nakata, Hajime; Nakayama, Chikashi (Univ. of Occupational and Environmental Health School of Medicine, Kitakyushu, Fukuoka (Japan)); Nishitani, Hiroshi; Matsuura, Keiichi

    1983-07-01

    We have reviewed the computed tomographic (CT) findings of 8 cases of benign retroperitoneal tumors with histological proof. Two teratomas, two schwannomas, and one each of epidermoid cyst, simple cyst, bronchogenic cyst, and cystic lymphangioma were included. The most common CT appearance of these tumors was the solitary, round, well-demarcated, relatively low density mass. Capsule or calcification was demonstrated in some. CT is a highly valuable non-invasive examination method for a diagnosis of a benign retroperitoneal tumor.

  19. Oblique detonation waves stabilized in rectangular-cross-section bent tubes

    OpenAIRE

    Kudo, Yusuke; Nagura, Yuuto; Kasahara, Jiro; Sasamoto, Yuya; Matsuo, Akiko

    2011-01-01

    Oblique detonation waves, which are generated by a fundamental detonation phenomenon occurring in bent tubes, may be applied to fuel combustion in high-efficiency engines such as a pulse detonation engine (PDE) and a rotating detonation engine (RDE). The present study has experimentally demonstrated that steady-state oblique detonation waves propagated stably through rectangular-cross-section bent tubes by visualizing these waves using a high-speed camera and the shadowgraph method. The obliq...

  20. Detonation Propagation in 180°Ribs of an Insensitive High Energy Explosive

    Institute of Scientific and Technical Information of China (English)

    S. N. Lubyatinsky; A. Yu. Garmashev; V. G. Israelyan; O. V. Kostitsin; B. G. Loboiko; V. A. Pashentsev; V. A. Sibilev; E. B. Smirnov; V. P. Filin

    2004-01-01

    @@ Steady detonation regimes, such as the detonation of explosive rate sticks, are of particular interest in studies of explosive reaction kinetics. If this is the case the detonation front shape as well as the fields of particle velocity, pressure etc. are steady in the system of coordinates linked to the detonation front. This facilitates the analysis of the experimental data obtained to verify or calibrate various detonation models.

  1. Multi-Dimensional Double Detonation of Sub-Chandrasekhar Mass White Dwarfs

    OpenAIRE

    Moll, Rainer; Woosley, Stanford E.

    2013-01-01

    Using 2D and 3D simulation, we study the "robustness" of the double detonation scenario for Type Ia supernovae, in which a detonation in the helium shell of a carbon-oxygen white dwarf induces a secondary detonation in the underlying core. We find that a helium detonation cannot easily descend into the core unless it commences (artificially) well above the hottest layer calculated for the helium shell in current presupernova models. Compressional waves induced by the sliding helium detonation...

  2. Adaptive multiresolution computations applied to detonations

    CERN Document Server

    Roussel, Olivier

    2015-01-01

    A space-time adaptive method is presented for the reactive Euler equations describing chemically reacting gas flow where a two species model is used for the chemistry. The governing equations are discretized with a finite volume method and dynamic space adaptivity is introduced using multiresolution analysis. A time splitting method of Strang is applied to be able to consider stiff problems while keeping the method explicit. For time adaptivity an improved Runge--Kutta--Fehlberg scheme is used. Applications deal with detonation problems in one and two space dimensions. A comparison of the adaptive scheme with reference computations on a regular grid allow to assess the accuracy and the computational efficiency, in terms of CPU time and memory requirements.

  3. Detonation Propagation through Nitromethane Embedded Metal Foam

    Science.gov (United States)

    Lieberthal, Brandon; Maines, Warren R.; Stewart, D. Scott

    2015-11-01

    There is considerable interest in developing a better understanding of dynamic behaviors of multicomponent systems. We report results of Eulerian hydrodynamic simulations of shock waves propagating through metal foam at approximately 20% relative density and various porosities using a reactive flow model in the ALE3D software package. We investigate the applied pressure and energy of the shock wave and its effects on the fluid and the inert material interface. By varying pore sizes, as well as metal impedance, we predict the overall effects of heterogeneous material systems at the mesoscale. In addition, we observe a radially expanding blast front in these heterogeneous models and apply the theory of Detonation Shock Dynamics to the convergence behavior of the lead shock.

  4. Programmable Electronic Delay Device for Detonator

    Directory of Open Access Journals (Sweden)

    A. Sudheer Babu

    2013-05-01

    Full Text Available Delay devices are used to perform various roles like aiding in sequential release of payload, providing safety in flight/ trajectory, enabling self-destruction of ammunitions, allowing blast of the warhead after penetration in runway/bunker, etc. The delay time is introduced to cause a series of detonation events from the explosive charge, in order to achieve desired efficiency. Inspite of many improvements performed along the years, in search of precise delay compositions, it is noticed that the obtained accuracy in chemical delay compositions is of ±4%.The present work using microcontroller gives possible accuracy of upto ±1%.This paper discusses about programmable electronic delay device, timing accuracy of electronic delay device and its merits over chemical delay devices.Defence Science Journal, 2013, 63(3, pp.305-307, DOI:http://dx.doi.org/10.14429/dsj.63.2880

  5. Stab Wound to the Face. A Case Presentation Herida facial por arma blanca. Presentación de un caso

    Directory of Open Access Journals (Sweden)

    Yordany Boza Mejias

    2012-05-01

    Full Text Available

    The case of a young male patient aged 34, brown skinned, of rural origin and with a history of good health is presented. The patient was admitted at the Emergency Room of the Dr. Gustavo Aldereguía Lima General University Hospital in Cienfuegos. As a result of a fight, he had received a stab wound to the left lower side of the face. Therefore, surgical emergency treatment was applied. The objective of this presentation is to emphasize the importance of a multifactorial attention that allows covering all vital parameters and controlling the patient's hemodynamic status as well as that of the laboratory study, as appropriate, in order to obtain a rapid and effective behavior.

    Se presenta el caso de un joven de 34 años de edad, sexo masculino, de color de piel mestiza, de procedencia rural, con antecedentes de salud, que se recibió en el área de código rojo del Cuerpo de Guardia del Hospital General Universitario Dr. Gustavo Aldereguía Lima, de Cienfuegos, con una herida por arma blanca en la región inferior izquierda de la cara, producto de una riña, por lo que se le aplicó tratamiento quirúrgico de urgencia. El objetivo de esta presentación es enfatizar en la importancia de una atención multifactorial, que permita atender los parámetros vitales y controlar el estado hemodinámico del paciente, así como de la realización del estudio de laboratorio que corresponda, para desarrollar una conducta rápida y eficaz.

  6. Spark-safe low-voltage detonator

    Science.gov (United States)

    Lieberman, M.L.

    1988-07-01

    A column of explosive in a low-voltage detonator which makes it spark-safe includes an organic secondary explosive charge of HMX in the form of a thin pad disposed in a bore of a housing of the detonator in an ignition region of the explosive column and adjacent to an electrical ignition device at one end of the bore. The pad of secondary charge has an axial thickness within the range of twenty to thirty percent of its diameter. The explosive column also includes a first explosive charge of CP disposed in the housing bore in the ignition region of the explosive column next to the secondary charge pad on a side opposite from the ignition device. The first CP charge is loaded under sufficient pressure, 25 to 40 kpsi, to provide mechanical confinement of the pad of secondary charge and physical coupling thereof with the ignition device. The explosive column further includes a second explosive charge of CP disposed in the housing bore in a transition region of the explosive column next to the first CP charge on a side opposite from the pad of secondary charge. The second CP charge is loaded under sufficient pressure, about 10 kpsi, to allow occurrence of DDT. The first explosive CP charge has an axial thickness within the range of twenty to thirty percent of its diameter, whereas the second explosive CP charge contains a series of increments (nominally 4), each of which has an axial thickness-to-diameter ratio of one to two. 2 figs.

  7. Thermonuclear detonations ensuing white dwarf mergers

    Science.gov (United States)

    Dan, M.; Guillochon, J.; Brüggen, M.; Ramirez-Ruiz, E.; Rosswog, S.

    2015-12-01

    The merger of two white dwarfs (WDs) has for many years not been considered as the favoured model for the progenitor system of Type Ia supernovae (SNe Ia). But recent years have seen a change of opinion as a number of studies, both observational and theoretical, have concluded that they should contribute significantly to the observed SN Ia rate. In this paper, we study the ignition and propagation of detonation through post-merger remnants and we follow the resulting nucleosynthesis up to the point where a homologous expansion is reached. In our study we cover the entire range of WD masses and compositions. For the emergence of a detonation we study three different setups. The first two are guided by the merger remnants from our earlier simulations, while for the third one the ignitions were set by placing hotspots with properties determined by spatially resolved calculations taken from the literature. There are some caveats to our approach which we investigate. We carefully compare the nucleosynthetic yields of successful explosions with SN Ia observations. Only three of our models are consistent with all the imposed constraints and potentially lead to a standard Type Ia event. The first one, a 0.45 M⊙ helium (He) + 0.9 M⊙ carbon-oxygen (CO) WD system produces a sub-luminous, SN 1991bg-like event while the other two, a 0.45 M⊙ He+1.1 M⊙ oxygen-neon WD system and a 1.05 + 1.05 M⊙ system with two CO WDs, are good candidates for common SNe Ia.

  8. Chapman-Jouguet deflagrations and their transition to detonation

    CERN Document Server

    Saif, Mohamed; Pekalski, Andrzej; Levin, Marc; Radulescu, Matei I

    2015-01-01

    We study experimentally fast flames and their transition to detonation in mixtures of methane, ethane, ethylene, acetylene, and propane mixtures with oxygen. Following the interaction of a detonation wave with a column of cylinders of varying blockage ratio, the experiments demonstrate that the fast flames established are Chapman-Jouguet deflagrations, in excellent agreement with the self-similar model of Radulescu et al. (2015). The experiments indicate that these Chapman-Jouguet deflagrations dynamically restructure and amplify into fewer stronger modes until the eventual transition to detonation. The transition length to a self-sustained detonation was found to correlate very well with the mixtures' sensitivity to temperature fluctuations, reflected by the $\\chi$ parameter introduced by Radulescu, which is the product of the non-dimensional activation energy $E_a/RT$ and the ratio of chemical induction to reaction time $t_i/t_r$. Correlation of the measured DDT lengths determined that the relevant characte...

  9. Numerical simulation of H2/air detonation using unstructured mesh

    Science.gov (United States)

    Togashi, Fumiya; Löhner, Rainald; Tsuboi, Nobuyuki

    2009-06-01

    To explore the capability of unstructured mesh to simulate detonation wave propagation phenomena, numerical simulation of H2/air detonation using unstructured mesh was conducted. The unstructured mesh has several adv- antages such as easy mesh adaptation and flexibility to the complicated configurations. To examine the resolution dependency of the unstructured mesh, several simulations varying the mesh size were conducted and compared with a computed result using a structured mesh. The results show that the unstructured mesh solution captures the detailed structure of detonation wave, as well as the structured mesh solution. To capture the detailed detonation cell structure, the unstructured mesh simulations required at least twice, ideally 5times the resolution of structured mesh solution.

  10. Non-ideal detonation behaviour of PBX 9502

    Science.gov (United States)

    Schoch, Stefan; Nikiforakis, Nikos

    2009-06-01

    Numerical experiments are performed investigating the non-ideal detonation behaviour of PBX 9502 in two setups. In the first setup we consider a three-dimensional rate stick experiment. A booster charge initiates a reaction front leading to a curved detonation wave. The numerical results are compared to theory and experimental evidence. The effects of weak and strong confinement are discussed. The second setup considers the so called ``hockey puck experiment.'' Experimental results show the appearance of a dead zone due to the effect of the geometry. This is captured by the numerical results, which also reveal that the initially spherical detonation is diffracted leading to local detonation failure. The numerical simulations are performed by solving a mathematical model for a three-phase medium based on the Euler equations. The numerical results are obtained using high-resolution shock-capturing methods combined with adaptive mesh refinement.

  11. Qualitative modeling of the dynamics of detonations with losses

    KAUST Repository

    Faria, Luiz

    2015-01-01

    We consider a simplified model for the dynamics of one-dimensional detonations with generic losses. It consists of a single partial differential equation that reproduces, at a qualitative level, the essential properties of unsteady detonation waves, including pulsating and chaotic solutions. In particular, we investigate the effects of shock curvature and friction losses on detonation dynamics. To calculate steady-state solutions, a novel approach to solving the detonation eigenvalue problem is introduced that avoids the well-known numerical difficulties associated with the presence of a sonic point. By using unsteady numerical simulations of the simplified model, we also explore the nonlinear stability of steady-state or quasi-steady solutions. © 2014 The Combustion Institute.

  12. Simulation Of Attenuation Regularity Of Detonation Wave In Pmma

    Science.gov (United States)

    Lan, Wei; Xiaomian, Hu

    2012-03-01

    Polymethyl methacrylate (PMMA) is often used as clapboard or protective medium in the parameter measurement of detonation wave propagation. Theoretical and experimental researches show that the pressure of shock wave in condensed material has the regularity of exponential attenuation with the distance of propagation. Simulation of detonation produced shock wave propagation in PMMA was conducted using a two-dimensional Lagrangian computational fluid dynamics program, and results were compared with the experimental data. Different charge diameters and different angles between the direction of detonation wave propagation and the normal direction of confined boundary were considered during the calculation. Results show that the detonation produced shock wave propagation in PMMA accords with the exponential regularity of shock wave attenuation in condensed material, and several factors are relevant to the attenuation coefficient, such as charge diameter and interface angle.

  13. [Detonation temperature measurement of epoxypropane using instantaneous spectrum method].

    Science.gov (United States)

    Li, Ying; Li, Ping; Xiao, Hai-Bo; Hu, Dong; Yuan, Chang-Ying

    2008-03-01

    After solving the problems of synchronization of the measuring system and the avoidance of false trigger signal, the instantaneous emission spectrum of epoxypropane with an exposure time of 2 micros and a resolution of 0.2 nm was acquired from a side window of a shock tube at the very moment when the epoxypropane transformed from deflagration to detonation. The measuring system consists of an advanced intensified charge-coupled-device spectroscopic detector, a digital delay generator DG535, an explosion shock tube and optical fibers. The DDT process was monitored by pressure transducers. After correcting the intensity of the spectrum obtained, the background curve of the heat radiation intensity of the detonation was given immediately. The detonation temperature of 2 416 K for epoxypropane was derived from fitting the curve with Planck blackbody formula by least squares principle. The detonation temperature of epoxypropane can provide an experimental datum for analyzing the microscopic mechanism of DDT process. PMID:18536396

  14. Temperature-based model for condensed-phase explosive detonation

    International Nuclear Information System (INIS)

    Simple reactive flow models for condensed explosives have four requirements: two equations of state (EOS), one for the unreacted condensed-phase explosive and one for its detonation products, a reaction rate law that converts the explosive in products and a mixture rule to compute the biphasic partially reacted states (with both unreacted explosive and products). Generally, the chemical reaction rates are governed by local temperature. Nonetheless, temperature fields are scarcely known, especially in detonating explosives. Hence this quantity is not provided by the usual unreacted explosive EOS with the required accuracy. As a consequence, for shock initiation and detonation phenomena, rate laws are based on easily measurable properties such as pressure, density, compression or particle velocity. In this work, we try to build a temperature-based reaction rate law. This model is expected to give interesting results as regards shock initiation and desensitization while remaining accurate for detonation propagation.

  15. Computations of supersonic flows: Shears, shocks, and detonations

    International Nuclear Information System (INIS)

    This paper describes some of the basic features of and physical mechanisms controlling two types of supersonic flows: detonations and supersonic shear layers. Gas-phase detonations are supersonic flows in which a leading shock is driven through an energetic material by local energy release. The material behind the leading shock front of a detonation is highly disturbed and contains many interacting shocks, shears layers, and reaction zones that produce cell-like patterns on the chamber containing the flow. Supersonic shear layers often are extremely irregular and noisy and show strong interactions between shocks and vortical structures. This paper first discusses the roll of shocks in suppressing mixing and vortex merging in shear flows, and then discusses the effects of shock interactions on pattern formation and vorticity generation behind propagating detonations

  16. Set-valued solutions for non-ideal detonation

    CERN Document Server

    Semenko, Roman; Kasimov, Aslan; Ermolaev, Boris

    2013-01-01

    The existence and structure of steady gaseous detonation propagating in a packed bed of solid inert particles are analyzed in the one-dimensional approximation by taking into consideration frictional and heat losses between the gas and the particles. A new formulation of the governing equations is introduced that eliminates the well-known difficulties with numerical integration across the sonic singularity in the reactive Euler equations. The new algorithm allows us to determine that the detonation solutions as the loss factors are varied have a set-valued nature at low detonation velocities when the sonic constraint disappears from the solutions. These set-valued solutions correspond to a continuous spectrum of the eigenvalue problem that determines the velocity of the detonation.

  17. Initiation of Detonation in Explosives by Impact of Projectiles

    OpenAIRE

    H. S. Yadav

    2006-01-01

    This paper presents a study of initiation of detonation in explosives by the impact ofprojectiles. The shock wave produced by the impact of projectiles has been considered as thestimulus for initiation of detonation. Three types of projectiles, namely (i) flyer plate, (ii) flatendedrod, and (iii) round-ended rod or a shaped charge jet, have been considered to impact andproduce a shock wave in the explosives. Deriving relations for the parameters of impact-generatedshock wave in the explosives...

  18. A kinetic approach to propagation and stability of detonation waves

    OpenAIRE

    Pandolfi, Miriam; Monaco, Roberto

    2009-01-01

    The problem of the steady propagation and linear stability of a detonation wave is formulated in the kinetic frame for a quaternary gas mixture in which a reversible bimolecular reaction takes place. The reactive Euler equations and related Rankine‐Hugoniot conditions are deduced from the mesoscopic description of the process. The steady propagation problem is solved for a Zeldovich, von Neuman and Doering (ZND) wave, providing the detonation profiles and the wave thickness for different over...

  19. The Influence of Interatomic Bonding Potentials on Detonation Properties

    OpenAIRE

    Heim, Andrew J.; Grønbech-Jensen, Niels; Germann, Timothy C.; Kober, Edward M.; Holian, Brad Lee; Lomdahl, Peter S.

    2006-01-01

    The dependence of macroscopic detonation properties of a two-dimensional diatomic (AB) molecular system on the fundamental properties of the molecule were investigated. This includes examining the detonation velocity, reaction zone thickness, and critical width as a function of the exothermicity of the gas-phase reaction and the gas-phase dissociation energy for. Following previous work, molecular dynamics (MD) simulations with a reactive empirical bond-order potential were used to characteri...

  20. Stability of viscous weak detonation waves for Majda's model

    OpenAIRE

    Hendricks, Jeffrey; Humpherys, Jeffrey; Lyng, Gregory; Zumbrun, Kevin

    2013-01-01

    Continuing the program initiated by Humpherys, Lyng, & Zumbrun [17] for strong detonation waves, we use a combination of analytical and numerical Evans-function techniques to analyze the spectral stability of weak detonation waves in a simplified model for gas-dynamical combustion. Combining these new spectral stability results with the pointwise Green function analysis of Lyng, Raoofi, Texier, & Zumbrun [22], we conclude that these waves are nonlinearly stable. The principal novelty of this ...

  1. Imaging malignant and apparent malignant transformation of benign gynaecological disease

    Energy Technology Data Exchange (ETDEWEB)

    Lee, A.Y.; Poder, L.; Qayyum, A.; Wang, Z.J.; Yeh, B.M. [Department of Radiology, University of California San Francisco, San Francisco, CA (United States); Coakley, F.V., E-mail: Fergus.Coakley@radiology.ucsf.ed [Department of Radiology, University of California San Francisco, San Francisco, CA (United States)

    2010-12-15

    Common benign gynaecological diseases, such as leiomyoma, adenomyosis, endometriosis, and mature teratoma, rarely undergo malignant transformation. Benign transformations that may mimic malignancy include benign metastasizing leiomyoma, massive ovarian oedema, decidualization of endometrioma, and rupture of mature teratoma. The aim of this review is to provide a contemporary overview of imaging findings in malignant and apparent malignant transformation of benign gynaecological disease.

  2. Imaging malignant and apparent malignant transformation of benign gynaecological disease

    International Nuclear Information System (INIS)

    Common benign gynaecological diseases, such as leiomyoma, adenomyosis, endometriosis, and mature teratoma, rarely undergo malignant transformation. Benign transformations that may mimic malignancy include benign metastasizing leiomyoma, massive ovarian oedema, decidualization of endometrioma, and rupture of mature teratoma. The aim of this review is to provide a contemporary overview of imaging findings in malignant and apparent malignant transformation of benign gynaecological disease.

  3. Minimum tube diameters for steady propagation of gaseous detonations

    Science.gov (United States)

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

    2014-07-01

    Recent experimental results on detonation limits are reported in this paper. A parametric study was carried out to determine the minimum tube diameters for steady detonation propagation in five different hydrocarbon fuel-oxygen combustible mixtures and in five polycarbonate test tube diameters ranging from 50.8 mm down to a small scale of 1.5 mm. The wave propagation in the tube was monitored by optical fibers. By decreasing the initial pressure, hence the sensitivity of the mixture, the onset of limits is indicated by an abrupt drop in the steady detonation velocity after a short distance of travel. From the measured wave velocities inside the test tube, the critical pressure corresponding to the limit and the minimum tube diameters for the propagation of the detonation can be obtained. The present experimental results are in good agreement with previous studies and show that the measured minimum tube diameters can be reasonably estimated on the basis of the /3 rule over a wide range of conditions, where is the detonation cell size. These new data shall be useful for safety assessment in process industries and in developing and validating models for detonation limits.

  4. Numerical simulation of Mach reflection of cellular detonations

    Science.gov (United States)

    Li, J.; Lee, J. H. S.

    2016-07-01

    The Mach reflection of cellular detonation waves on a wedge is investigated numerically in an attempt to elucidate the effect of cellular instabilities on Mach reflection, the dependence of self-similarity on the thickness of a detonation wave, and the initial development of the Mach stem near the wedge apex. A two-step chain-branching reaction model is used to give a thermally neutral induction zone followed by a chemical reaction zone for the detonation wave. A sufficiently large distance of travel of the Mach stem is computed to observe the asymptotic behavior in the far field. Depending on the scale at which the Mach reflection process occurs, it is found that the Mach reflection of a cellular detonation behaves essentially in the same way as a planar ZND detonation wave. The cellular instabilities, however, cause the triple-point trajectory to fluctuate. The fluctuations are due to interactions of the triple point of the Mach stem with the transverse waves of cellular instabilities. In the vicinity of the wedge apex, the Mach reflection is found to be self-similar and corresponds to that of a shock wave of the same strength, since the Mach stem is highly overdriven initially. In the far field, the triple-point trajectory approaches a straight line, indicating that the Mach reflection becomes self-similar asymptotically. The distance of the approach to self-similarity is found to decrease rapidly with decreasing thickness of the detonation front.

  5. Detonation performance of high-dense BTF charges

    Science.gov (United States)

    Dolgoborodov, Alexander; Brazhnikov, Michael; Makhov, Michael; Gubin, Sergey; Maklasova, Irina

    2013-06-01

    New experimental data on detonation wave parameters and explosive performance for benzotrifuroxan (BTF) are presented. Optical pyrometry was applied in order to measure the temperature and pressure of BTF detonation products. Chapman-Jouguet pressure and temperature were obtained as following: 33.8 GPa and 3990 K; 34.5 GPa and 4170 K (initial charge densities 1.82 and 1.84 g/cc respectively), the polytropic exponent was estimated as 2.8. The heat of explosion and acceleration ability were measured also. The results of calorimetric measurements performed in bomb calorimeter indicate that BTF slightly surpasses HMX in the heat of explosion. However BTF is inferior to HMX in the acceleration ability, measured by the method of copper casing expansion. It is also considered the hypothesis of formation of nanocarbon particles in detonation products directly behind the detonation front and influence of this processes on the temperature-time history in detonation products. The results of calculations with in view of formation of liquid nanocarbon in products of a detonation also are presented.

  6. Evaluating detonation possibilities in a Hanford radioactive waste tank

    Energy Technology Data Exchange (ETDEWEB)

    Travis, J.R.; Fujita, R.K.; Ross, M.C.; Edwards, J.N. [Los Alamos National Lab., NM (United States); Shepherd, J.E. [California Inst. of Tech., Pasadena, CA (United States)

    1994-07-01

    Since the early 1940s, radioactive wastes generated from the defense operations at the Hanford Site have been stored in underground waste storage tanks. During the intervening years, the waste products in some of these tanks have transformed into a potentially hazardous mixture of gases and solids as a result of radiolytic and thermal chemical reactions. One tank in particular, Tank 101-SY, has been periodically releasing high concentrations of a hydrogen/nitrous oxide/nitrogen/ ammonia gas mixture into the tank dome vapor space. There are concerns that under certain conditions a detonation of the flammable gas mixture may occur. There are two ways that a detonation can occur during a release of waste gases into the dome vapor splice: (1) direct initiation of detonation by a powerful ignition source, and (2) deflagration to detonation transition (DDT). The first case involves a strong ignition source of high energy, high power, or of large size (roughly 1 g of high explosive (4.6 kj) for a stoichiometric hydrogen-air mixture{sup 1}) to directly initiate a detonation by ``shock`` initiation. This strong ignition is thought to be incredible for in-tank ignition sources. The second process involves igniting the released waste gases, which results in a subsonic flame (deflagration) propagating into the unburned combustible gas. The flame accelerates to velocities that cause compression waves to form in front of the deflagration combustion wave. Shock waves may form, and the combustion process may transition to a detonation wave.

  7. Numerical investigations on reignition behavior of detonation diffraction

    Science.gov (United States)

    Wang, Cheng; Han, Wen-Hu; Bi, Yong; Ding, Jian-Xu

    2016-02-01

    In this paper, by adopting a fifth-order weighted essentially non-oscillatory (WENO) scheme with a third-order TVD Runge-Kutta time stepping method for two-dimensional reactive Euler equations, a parallel code is developed, and reignition behavior after a self-sustaining detonation from the tube into free space filled with H2/O2 mixtures is investigated. The numerical results show that the initial pressure has a great influence on the detonation cellular width, and that as the initial pressure increases, the cellular width gradually decreases and the cellular shape changes from irregular structure to regular structure, demonstrating the detonation instability to stability transition. When the initial pressure is larger than 1.2 atm, the detonation wave expands over the edge of the splitter plate, reignition can come into being because enough transverse waves collide with each other at the leading edge of the expanding front. When the initial pressure is 1.2 atm, hot spots appear on the front, and ignite the combustible gas near the hot spots after detonation diffraction. When the initial pressure is 1.0 atm, reignition fails. These findings hint that a critical initial pressure exists between 1.0-1.2 atm for direct reignition after detonation diffraction.

  8. Evaluating detonation possibilities in a Hanford radioactive waste tank

    International Nuclear Information System (INIS)

    Since the early 1940s, radioactive wastes generated from the defense operations at the Hanford Site have been stored in underground waste storage tanks. During the intervening years, the waste products in some of these tanks have transformed into a potentially hazardous mixture of gases and solids as a result of radiolytic and thermal chemical reactions. One tank in particular, Tank 101-SY, has been periodically releasing high concentrations of a hydrogen/nitrous oxide/nitrogen/ ammonia gas mixture into the tank dome vapor space. There are concerns that under certain conditions a detonation of the flammable gas mixture may occur. There are two ways that a detonation can occur during a release of waste gases into the dome vapor splice: (1) direct initiation of detonation by a powerful ignition source, and (2) deflagration to detonation transition (DDT). The first case involves a strong ignition source of high energy, high power, or of large size (roughly 1 g of high explosive (4.6 kj) for a stoichiometric hydrogen-air mixture1) to directly initiate a detonation by ''shock'' initiation. This strong ignition is thought to be incredible for in-tank ignition sources. The second process involves igniting the released waste gases, which results in a subsonic flame (deflagration) propagating into the unburned combustible gas. The flame accelerates to velocities that cause compression waves to form in front of the deflagration combustion wave. Shock waves may form, and the combustion process may transition to a detonation wave

  9. Benign fracture versus malignant vertebral body infiltration

    International Nuclear Information System (INIS)

    MR imaging capabilities in differentiating marrow signal alterations seen in benign vertebral body compression fractures from those of malignant vertebral infiltration were assessed. Thirty-six patients, including 15 with posttraumatic vertebral compression fractures of known age, and 21 with malignant bone lesions, were imaged with MR. MR spine imaging (1.5 T) was performed with routine spin-echo sequences as well as inversion recovery (STIR), gradient-echo scans (GRASS), and chemical shift images (selective saturation technique) to obtain fat and water scans. Fat/water images enhanced differentiation between benign and malignant signal alterations. In general, patients with malignancy showed abnormal diffuse low signal intensity on fat images and corresponding increased signal on water images. Benign compression fractures showed variable patterns of signal alteration on fat/water images depending on fracture age. Old fractures showed persistent fat signal. Only very acute traumatic fractures showed increased signal on water images

  10. Benign multicystic peritoneal mesothelioma: a case report

    Directory of Open Access Journals (Sweden)

    Papapaulou Leonidas

    2010-11-01

    Full Text Available Abstract Introduction We report the case of a patient with a benign multicystic peritoneal mesothelioma and describe its appearance on computed tomography scans and ultrasonography, in correlation with gross clinical and pathological findings. Case presentation A 72-year-old Caucasian woman presented to our emergency department with acute abdomen signs and symptoms. A clinical examination revealed a painful palpable mass in her left abdomen. Abdominal ultrasonography and computed tomography demonstrated the presence of a large cystic mass in her left upper abdomen, adjacent to her left hemidiaphragm. The lower border of the mass extended to the upper margin of her pelvis. A complete resection of the lesion was performed. Pathological analysis showed a benign multicystic peritoneal mesothelioma. Conclusions Benign multicystic peritoneal mesothelioma is a rare lesion with a non-specific appearance on imaging. Its diagnosis always requires pathological analysis.

  11. Pharmacological treatment of the benign prostatic hyperplasia

    International Nuclear Information System (INIS)

    Benign prostatic hyperplasia is a common disease in over 50 years-old men consisting in uncontrolled and benign growth of prostatic gland that leads to lower urinary tract symptoms. The etiology of benign prostatic hyperplasia is multifactoral involving the increased conversion of testosterone in dihydrotestosterone by the prostatic 5α-reductase action, which brought about events that encourage the prostate growth (static component) and the increase of the bladder and prostate smooth muscle tone (dynamic component) regulated by the aα1 -adrenoceptors (ADR). The pharmacological treatment of the benign prostatic hyperplasia includes the prostatic 5aα-reductase inhibitors, the aα1-adrenoreceptor blockers, their combined therapy and the phytotherapy. This paper was aimed at presenting the most relevant aspects of the pharmacology of drugs used for treating the benign prostatic hyperplasia, and providing elements to analyze their efficacy, safety and tolerability. To this end, a review was made of the different drugs for the treatment of this pathology and they were grouped according to their mechanism of action. Natural products were included as lipid extracts from Serenoa repens and Pygeum africanum as well as D-004, a lipid extract from Roystonea regia fruits, with proved beneficial effects on the main etiological factors of benign prostatic hyperplasia. D-004 is a prostatic 5a-reductase inhibitor, an aα1-adrenoceptor antagonist, aα 5-lipooxygenase inhibitor and has antioxidant action, all of which reveals a multifactoral mechanism. The results achieved till now indicate that D-004 is a safe and well-tolerated product

  12. Predicting propagation limits of laser-supported detonation by Hugoniot analysis

    Science.gov (United States)

    Shimamura, Kohei; Ofosu, Joseph A.; Komurasaki, Kimiya; Koizumi, Hiroyuki

    2015-01-01

    Termination conditions of a laser-supported detonation (LSD) wave were investigated using control volume analysis with a Shimada-Hugoniot curve and a Rayleigh line. Because the geometric configurations strongly affect the termination condition, a rectangular tube was used to create the quasi-one-dimensional configuration. The LSD wave propagation velocity and the pressure behind LSD were measured. Results reveal that the detonation states during detonation and at the propagation limit are overdriven detonation and Chapman-Jouguet detonation, respectively. The termination condition is the minimum velocity criterion for the possible detonation solution. Results were verified using pressure measurements of the stagnation pressure behind the LSD wave.

  13. The decline of hysterectomy for benign disease.

    LENUS (Irish Health Repository)

    Horgan, R P

    2012-01-31

    Hysterectomy is one of the most common gynaecological surgical procedures performed but there appears to be a decline in the performance of this procedure in Ireland in recent times. We set out to establish the extent of the decline of hysterectomy and to explore possible explanations. Data for hysterectomy for benign disease from Ireland was obtained from the Hospital In-Patient Enquiry Scheme (HIPE) section of the Economic and Social Research Institute for the years 1999 to 2006. The total number of hysterectomies performed for benign disease showed a consistent decline during this time. There was a 36% reduction in the number of abdominal hysterectomy procedures performed.

  14. Diagnostik og behandling af benigne levertumorer

    DEFF Research Database (Denmark)

    Eriksen, Peter Lykke; Schultz, Nicolai Aagaard; Larsen, Lars Peter;

    2016-01-01

    Due to the expanding use of diagnostic imaging, an increasing number of liver tumours are discovered. Benign tumours are very common; they rarely cause symptoms and often they do not require any treatment. However, because of differences in the natural history including risk of complications and...... malignant transformation exact diagnosis is important. Dedicated radiological examinations serve as important diagnostic tools reducing the need for biopsy. In this review we provide an update on the diagnosis and treatment of benign liver tumours adding to existing recommendations on hepatocellular...

  15. Reducing the Consequences of a Nuclear Detonation.

    Energy Technology Data Exchange (ETDEWEB)

    Buddemeier, B R

    2007-11-09

    The 2002 National Strategy to Combat Weapons of Mass Destruction states that 'the United States must be prepared to respond to the use of WMD against our citizens, our military forces, and those of friends and allies'. Scenario No.1 of the 15 Department of Homeland Security national planning scenarios is an improvised nuclear detonation in the national capitol region. An effective response involves managing large-scale incident response, mass casualty, mass evacuation, and mass decontamination issues. Preparedness planning activities based on this scenario provided difficult challenges in time critical decision making and managing a large number of casualties within the hazard area. Perhaps even more challenging is the need to coordinate a large scale response across multiple jurisdictions and effectively responding with limited infrastructure and resources. Federal response planning continues to make improvements in coordination and recommending protective actions, but much work remains. The most critical life-saving activity depends on actions taken in the first few minutes and hours of an event. The most effective way to reduce the enormous national and international social and economic disruptions from a domestic nuclear explosion is through planning and rapid action, from the individual to the federal response. Anticipating response resources for survivors based on predicted types and distributions of injuries needs to be addressed.

  16. Detonation Type Ram Accelerator: A Computational Investigation

    Directory of Open Access Journals (Sweden)

    Sunil Bhat

    2000-01-01

    Full Text Available An analytical model explaining the functional characteristics of detonation type ram accelerator is presented. Major flow processes, namely, (i supersonic flow over the cone of the projectile, (ii initiation ofconical shock wave and its reflection from the tube wall, (iii supersonic combustion, and (iv expansion wave and its reflection are modelled. Taylor-Maccoll approach is adopted for modellingthe flow over the cone of the projectile. Shock reflection is treated in accordance with wave angle theorytor flows over the wedge. Prandtl-Mayer analysis is used to model the expansion wave and its reflection.Steady one-dimensional flow with heat transfer along with Rayleigh line equation for perfect gases isused to model supersonic combustion. A computer code is developed to compute the thrust producedby combustion of gases. Ballistic parameters like thrust-pressure ratio and ballistic efficiency of the accelerator are evaluated and their maximum values are 0.032 and 0.068, respectively. The code indicates possibility ofachieving high velocity of 7 km/s on utilising gaseous mixture of 2H2+O2 in the operation.Velocity range suitable for operation of the accelerator lies between 3.8 - 7.0 km/s. Maximum thrust valueis 33721 N which corresponds to the projectile velocity of 5 km/s.

  17. Propagation of Axially Symmetric Detonation Waves

    Energy Technology Data Exchange (ETDEWEB)

    Druce, R L; Roeske, F; Souers, P C; Tarver, C M; Chow, C T S; Lee, R S; McGuire, E M; Overturf, G E; Vitello, P A

    2002-06-26

    We have studied the non-ideal propagation of detonation waves in LX-10 and in the insensitive explosive TATB. Explosively-driven, 5.8-mm-diameter, 0.125-mm-thick aluminum flyer plates were used to initiate 38-mm-diameter, hemispherical samples of LX-10 pressed to a density of 1.86 g/cm{sup 3} and of TATB at a density of 1.80 g/cm{sup 3}. The TATB powder was a grade called ultrafine (UFTATB), having an arithmetic mean particle diameter of about 8-10 {micro}m and a specific surface area of about 4.5 m{sup 2}/g. Using PMMA as a transducer, output pressure was measured at 5 discrete points on the booster using a Fabry-Perot velocimeter. Breakout time was measured on a line across the booster with a streak camera. Each of the experimental geometries was calculated using the Ignition and Growth Reactive Flow Model, the JWL++ Model and the Programmed Burn Model. Boosters at both ambient and cold (-20 C and -54 C) temperatures have been experimentally and computationally studied. A comparison of experimental and modeling results is presented.

  18. Efficiency of Pulsed Detonation Thermal Spraying

    Science.gov (United States)

    Cannon, Jacob E.; Alkam, Mohammad; Butler, P. Barry

    2008-12-01

    Pulsed detonation thermal spray coating is used to enhance the material properties at the surface of an object. The present research implements computational fluid dynamic modeling to identify the efficiency of energy and mass delivered to potential target locations. Six cases of a hydrogen-air mixture are used to investigate the gas flow from the instant of ignition to the instant of flow reversal at the tube exit. Flow monitors are included in the model to represent potential target locations. These monitors are placed at different axial locations in order to record mass flow rate and the flow rate of enthalpy over time. The results indicate that there exists a quasi-steady jet that is efficient and predictable in delivery of energy and mass from the tube exit to potential target locations positioned on the centerline. The duration of the quasi-steady jet is dependent on the fraction of combustible gas (i.e., % fill). Much of the initial energy and mass delivered from the jet avoids the flow monitors. This is found to be related to the evolution of the jet behind the blast wave where energy is lost in expansion and vorticity production. It is also found that nearly 11-18% of the available energy and 20-23% of the available mass remains in the tube after flow reversal.

  19. TRENDS IN THE DEVELOPMENT OF DETONATION ENGINES FOR HIGH-SPEED AEROSPACE AIRCRAFTS AND THE PROBLEM OF TRIPLE CONFIGURATIONS OF SHOCK WAVES. Part I. Research of detonation engines

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2016-01-01

    Full Text Available We consider current problems of improving propulsion systems of highly supersonic air-space vehicles. In the first part, we review historic developments and list the landmark scientific papers. Classification of detonation engines is presented with detailed consideration of rotation detonation engines and continuous detonation engines. Experimental results on detonation, which are of particular importance for the design of detonation engines, are discussed. The second part of the paper provides an overview of the development in detonation theory, mathematical modelling, and numerical simulation. We focus on the interference of shock waves with formation of triple points, regular and irregular reflection of shock waves, existence of multiple solutions and the resulting appearance of hysteresis. The relevance and importance of triple shock wave configurations for the development of new types of air intakes and detonation jet engines is demonstrated.

  20. The development of laser ignited deflagration-to-detonation transition (DDT) detonators and pyrotechnic actuators

    Energy Technology Data Exchange (ETDEWEB)

    Merson, J.A.; Salas, F.J.

    1994-05-01

    The use of laser ignited explosive components has been recognized as a safety enhancement over existing electrical explosive devices (EEDs). Sandia has been pursuing the development of optical ordnance for many years with recent emphasis on developing optical deflagration-to-detonation (DDT) detonators and pyrotechnic actuators. These low energy optical ordnance devices can be ignited with either a semiconductor diode laser, laser diode arrays or a solid state rod laser. By using a semiconductor laser diode, the safety improvement can be made without sacrificing performance since the input energy required for the laser diode and the explosive output are similar to existing electrical systems. The use of higher powered laser diode arrays or rod lasers may have advantages in fast DDT applications or lossy optical environments such as long fiber applications and applications with numerous optical connectors. Recent results from our continued study of optical ignition of explosive and pyrotechnic materials are presented. These areas of investigation can be separated into three different margin categories: (1) the margin relative to intended inputs ( i.e. powder performance as a function of laser input variation), (2) the margin relative to anticipated environments (i.e. powder performance as a function of thermal environment variation), and (3) the margin relative to unintended environments (i.e. responses to abnormal environments or safety).

  1. Three-dimensional numerical simulation of detonations in coaxial tubes

    Science.gov (United States)

    Tsuboi, Nobuyuki; Daimon, Yu; Hayashi, A. Koichi

    2008-10-01

    Three-dimensional numerical simulation of detonations in both a circular tube and a coaxial tube are simulated to reveal characteristics of single spinning and two-headed detonations. The numerical results show a feature of a single spinning detonation which was discovered in 1926. Transverse detonations are observed in both tubes, however, the single spinning mode maintains the complex Mach reflection whereas the two-headed mode develops periodically from the single Mach reflection to the complex one. The calculated cell aspect ratio for the two-headed mode changes from 1.09 to 1.34 as the radius of axial insert increases from r 1/ R = 0.1 to 0.9. The calculated cell aspect ratio for r 1/ R = 0.1 is close to the experimental results without an axial insert. The formation of an unreacted gas pocket behind the detonation front was not observed in the single spinning mode; however, the two-headed mode has unreacted gas pocket behind the front near the axial insert.

  2. Dynamics of detonations with a constant mean flow divergence

    CERN Document Server

    Borzou, Bijan

    2016-01-01

    The present work addresses the question of whether mean field macroscopic models are suitable to describe the dynamics of real cellular detonations. This question is posed in the framework of detonations with stream-tube area divergence that is kept constant, as to generate attenuated detonations in quasi-steady state. An exponential horn geometry is used, in order to keep the source term due to geometrical divergence constant in the governing equations of mean flow, and hence permit to establish steady travelling waves with constant losses. The experiments were conducted in two mixtures 2C$_2$H$_2$+5O$_2$+21Ar, characterized by a relatively weak instability, and C$_3$H$_8$+5O$_2$, characterized by a much more unstable cellular structure. The experiments demonstrated that such quasi-steady state detonations can be realized. The experiments permitted a unique detonation speed - divergence scaling laws to be developed. Quantitative comparisons were made with steady wave predictions based on the underlying chemi...

  3. Development of an Actuator for Flow Control Utilizing Detonation

    Science.gov (United States)

    Lonneman, Patrick J.; Cutler, Andrew D.

    2004-01-01

    Active flow control devices including mass injection systems and zero-net-mass flux actuators (synthetic jets) have been employed to delay flow separation. These devices are capable of interacting with low-speed, subsonic flows, but situations exist where a stronger crossflow interaction is needed. Small actuators that utilize detonation of premixed fuel and oxidizer should be capable of producing supersonic exit jet velocities. An actuator producing exit velocities of this magnitude should provide a more significant interaction with transonic and supersonic crossflows. This concept would be applicable to airfoils on high-speed aircraft as well as inlet and diffuser flow control. The present work consists of the development of a detonation actuator capable of producing a detonation in a single shot (one cycle). Multiple actuator configurations, initial fill pressures, oxidizers, equivalence ratios, ignition energies, and the addition of a turbulence generating device were considered experimentally and computationally. It was found that increased initial fill pressures and the addition of a turbulence generator aided in the detonation process. The actuators successfully produced Chapman-Jouguet detonations and wave speeds on the order of 3000 m/s.

  4. Detonation Reaction Zone Measurements of PBX 9501 and PBX 9502

    Science.gov (United States)

    Vincent, Samuel; Short, Mark; Jackson, Scott

    2013-06-01

    Explosives are often confined by inert materials. During detonation, the high pressures associated with the detonation reaction zone and expansion of products induce motion in the confiner. Classical programmed burn models for conventional high explosives (CHEs) performance do not aim to accurately capture the contribution to CHE drive from the short (100-200 micron) detonation reaction zone, as the drive is dominated by expansion of detonation products. However, the reaction zone lengths of insensitive (millimeter-scale) and non-ideal explosives (millimeter-to-centimeter-scale) are long enough that a significant contribution to the HE work on the confiner occurs within the reaction zone. Thus accurate prediction of the reaction zone flow structure and mechanical state is crucial to accurately model the motion of confiners driven by insensitive and non-ideal explosives. In this work, we have measured particle velocity profiles of detonation reaction zones in PBX 9501 and PBX 9502 slab geometries at the breakout surface using PDV imaging through LiF windows. We compare this data to model predictions in the slab geometry using the Wescott-Stewart-Davis reactive burn model and comment on the model performance.

  5. Non ideal detonation of emulsion explosives mixed with metal particles

    Science.gov (United States)

    Mendes, Ricardo; Ribeiro, José B.; Plaksin, I.; Campos, Jose

    2012-03-01

    The detonation of ammonium nitrate based compositions like emulsion explosives mixed with metal particles was experimentally investigated. Aluminum powder with a mean particle size of 6 μm was used, and the mass concentration of aluminum on the explosive charge ranged from 0 to 30% wt. The values of the detonation velocity, the pressure attenuation - P(x) - of the shock front amplitude in a standard PMMA monitor and manganin gauges pressure-time histories are shown as a function of the explosive charge porosity and specific mass. All these parameters except the pressuretimes histories have been evaluated using the multi-fiber optical probe (MFOP) method which is based on the use of an optical fiber strip, with 64 independent optical fibers. The MFOP allows a quasicontinuous evaluation of the detonation wave run propagation and the assessment of spatial resolved measurements of the shock wave induced in the PMMA barrier. Results of that characterization process are presented and discussed for aluminized and non-aluminized emulsion explosives. The experimental results have shown that the detonation velocity decreases monotonically with the increase of aluminum content. Nevertheless the peak of detonation pressure profiles presents a non-monotonic behavior increasing its value up to an Al content of 20% wt, after which it starts to decrease.

  6. Plastic deformation and tube rupture under radiolytic gas detonation loads

    International Nuclear Information System (INIS)

    Experiments on the plastic deformation of 34-mm (nominal) U-shaped pipes and their rupture have been performed in order to extend experiments on the mechanical response of pipe structures to the internal radiolytic gas detonation loads at BWR relevant conditions. Stoichiometric hydrogen-oxygen mixtures were used as a worst case of radiolytic gas composition. Austenitic stainless steel (Werkstoff Nr. 1.4435) and ferritic carbon steel (STPT 410) were used for tested tubes. The dynamic tube response was investigated under radiolytic gas detonation loads at initial pressures up to 70 bar and at room temperature. A dynamic stress-strain diagram from elastic to plastic deformations at strain rates from 100 to 2000 s-1 with subsequent rupture of the tested tubes were experimentally obtained, using direct strain measurements and high speed movies. Breaking elongations of 45 - 54% for austenitic 2-mm wall thickness tube were achieved due to radiolytic gas detonation loads at 50 and 57 bar of initial pressure. Ferritic tubes (4.5 mm nominal wall thickness) survived detonations of radiolytic gas at initial pressures of 40 and 70 bar. The maximum deformation achieved was less than 0.4% with a strain amplification factor of 1.2-2.5. The present experimental data are required to study the tube integrity under radiolytic gas detonation loads and to obtain experimental data on the dynamic strain-stress relations for computer code validation. (author)

  7. Numerical simulation of three-dimensional gas detonation

    International Nuclear Information System (INIS)

    We investigate the characteristics of the three-dimensional detonation in an argon-diluted mixture of hydrogen and oxygen. The three-dimensional Euler equations with a simple chemical reaction model are used as the governing equations for the detonation problem. The spatial derivatives are evaluated using the WENO scheme, and the temporal derivative is calculated using the TVD Runge-Kutta method. It is verified that the detonation front is composed of incident shocks and Mach stems, joined at the lines of triple points by transverse waves. And the clear cellular structure is displayed by using a three-dimensional numerical visualization. The process of generating unburned gas pockets is shown by the spatial isosurface profiles of the reaction progress parameter in the exothermic period, and it is explained that the triple lines play a role of 'shutter'. Furthermore, the rectangles, enclosed by the triple lines, vary with the movement of the triple lines. Consequently, the evolution between the diagonal detonation and the rectangular detonation is realized

  8. Gas-particle interaction in detonation spraying systems

    Science.gov (United States)

    Kadyrov, E.

    1996-06-01

    A model is developed to describe dynamic interaction of particles with the carrier gas during detonation spraying. Equations of mass, energy, and momentum conservation are integrated numerically for the two-phase particle-gas flow with the Hugoniot boundary conditions at the detonation wave front. Velocity and temperature of the sprayed powder and the gas parameters are calculated self-consistently, taking into account effects of friction and cooling of the gas in the vicinity of the gun barrel and effects of particle-gas interaction on the parameters of the gas phase. Calculations are performed for tungsten carbide particles of 30 μm diam and a 1.8 m long detonation gun using a stoichiometric mixture of oxygen and propane. Distributions of gas and particle parameters along the barrel are calculated for various moments of time. Tungsten carbide particles of 30 μm reach an exit velocity of 1278 m/s and a temperature of 1950 K. Exit particle velocity is a nonmonotonic function of the loading distance, L, with a distinct maximum at L = 75 cm. The proposed model can be applied to a broad range of problems related to detonation coating technology and allows evaluation of the effectiveness of various designs and optimization of operational parameters of detonation spraying systems.

  9. Investigations on detonation shock dynamics and related topics. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, D.S. [Univ. of Illinois, Urbana, IL (United States). Dept. of Theoretical and Applied Mechanics

    1993-11-01

    This document is a final report that summarizes the research findings and research activities supported by the subcontract DOE-LANL-9-XG8-3931P-1 between the University of Illinois (D. S. Stewart Principal Investigator) and the University of California (Los Alamos National Laboratory, M-Division). The main focus of the work has been on investigations of Detonation Shock Dynamics. A second emphasis has been on modeling compaction of energetic materials and deflagration to detonation in those materials. The work has led to a number of extensions of the theory of Detonation Shock Dynamics (DSD) and its application as an engineering design method for high explosive systems. The work also enhanced the hydrocode capabilities of researchers in M-Division by modifications to CAVEAT, an existing Los Alamos hydrocode. Linear stability studies of detonation flows were carried out for the purpose of code verification. This work also broadened the existing theory for detonation. The work in this contract has led to the development of one-phase models for dynamic compaction of porous energetic materials and laid the groundwork for subsequent studies. Some work that modeled the discrete heterogeneous behavior of propellant beds was also performed. The contract supported the efforts of D. S. Stewart and a Postdoctoral student H. I. Lee at the University of Illinois.

  10. Natural history of benign prostate hyperplasia

    Institute of Scientific and Technical Information of China (English)

    WU Shi-liang; LI Ning-chen; XIAO Yun-xiang; JIN Jie; QIU Shao-peng; YE Zhang-qun; KONG Chui-ze; SUN Guang; NA Yan-qun

    2006-01-01

    Background Benign prostate hyperplasia is one of the most common diseases affecting the health of the aging males. Watchful waiting is an acceptable management strategy for benign prostate hyperplasia in which the patient is monitored by the physician but receives no active intervention. The epidemiological data on this are lacking in China. Our study was designed to evaluate the changes of signs and symptoms of patients with benign prostate hyperplasia during management by watchful waiting in China.Methods One hundred and forty-five patients with benign prostate hyperplasia aged > 50 years were enrolled in management by watchful waiting. All the patients were visited every 6 months and were given an International Prostate Symptom Score and Quality of Life questionnaire to complete. They also had uroflowmetry and were assessed using ultrasonography to get the volume of prostate, transition zone and amount of residual urine. The Student's t test, the Chi-square test, and variance analysis were used in the statistical analysis.Results All patients were visited after 6 months, the mean volume of transitional zone was found to haveincreased by 1.6 ml (P<0.01), International Prostate Symptom Score was increased by 0.8 (P<0.01) and Quality of Life was increased by 0.2 (P<0.01), and there was no statistical change in other data. Among these patients,17.9% (26/145) visited again after 12 months when the data failed to show a statistically significant difference among the three groups (0, 6, and 12 months).Conclusions After one year's follow-up, the progression of benign prostate hyperplasia was slow and the clinical data did not undergo much change.

  11. Effect of detonation nanodiamonds on phagocyte activity.

    Science.gov (United States)

    Karpukhin, Alexey V; Avkhacheva, Nadezhda V; Yakovlev, Ruslan Yu; Kulakova, Inna I; Yashin, Valeriy A; Lisichkin, Georgiy V; Safronova, Valentina G

    2011-07-01

    Detonation ND (nanodiamond) holds much promise for biological studies and medical applications. Properties like size of particles, inclination for modification of their surface and unambiguous biocompatibility are crucial. Of prime importance is interaction between ND and immune cells, which supervise foreign intrusion into an organism and eliminate it. Neutrophils are more reactive in inflammatory response implementing cytotoxical arsenal including ROS (reactive oxygen species). The aim of the work was to estimate the ability of two ND samples (produced by Diamond Center and PlasmaChem) to keep the vitality of neutrophils from the inflammatory site. The ability of cells to generate ROS in the presence of ND particles is considered as indicating their biocompatibility. IR spectra and size of particles in the samples were characterized. Acid modification of ND was carried out to get the luminescent form. In the biological aspect, ND demonstrated up or down action, depending on the concentration, time and conditions of activation of cells. Weak action of ND in whole blood was obtained possibly owing to the ND adsorbed plasma proteins, which mask active functional groups to interact with the cell membrane. ND did not influence the viability of isolated inflammatory neutrophils in low and moderate concentrations and suppressed it in high concentrations (≥1 g/l). Addition of ND to the cell suspension initiated concentration-dependent reaction to produce ROS similar to respiratory burst. ND up-regulated response to bacterial formylpeptide, but up- and down-modified (low or high concentrations, accordingly) response to such bacterial agents as OZ (opsonized zymosan), which neutrophils swallow up by oxygen-dependent phagocytosis. Localization of the particles on the cell surface as into the cells was identified by monitoring the intrinsic fluorescence of oxidized ND. The various mechanisms that could account for penetration of ND particles into the cell are discussed

  12. Reflected Detonation Waves: Comparing Theory to Pressure and Heat Flux Measurements

    Science.gov (United States)

    Damazo, J.; Shepherd, J. E.

    Gaseous detonations are of concern to engineers designing piping systems for chemical and nuclear processing facilities. Recently, engineers have also begun to explore the possibility of harnessing the impulse created by detonations for thrust.

  13. Endo-biliary stents for benign disease: not always benign after all!

    Directory of Open Access Journals (Sweden)

    Jo-Etienne Abela

    2011-11-01

    Full Text Available This case report describes the presentation, management and treatment of a patient who suffered small bowel perforation due to the migration of his biliary stent which had been inserted for benign disease.

  14. Initiation and sustaining mechanisms of stabilized Oblique Detonation Waves around projectiles

    OpenAIRE

    Maeda, shinichi; Sumiya, Satoshi; Kasahara, Jiro; Matsuo, Akiko

    2013-01-01

    Direct initiations and stabilizations of three-dimensional conical detonation waves were attained by launching spheres with 1.06–1.31 times the C–J velocities into detonable mixtures. We conducted high time-resolution Schlieren visualizations of the whole processes over unsteady initiations to stable propagations of the stabilized Oblique Detonation Waves (ODWs) using a high-speed camera. The detonable mixtures were stoichiometric oxygen mixtures with acetylene, ethylene or hydrogen. They wer...

  15. Characterization of ethylene/JP-10 fuel injection profiles for a valveless pulse detonation engine

    OpenAIRE

    Danaher, Thomas J.

    2007-01-01

    Practical use of the pulse detonation engine as a form of propulsion for future aircraft and missile platforms depends upon the ability to reliably detonate a fuel air mixture at high frequencies in order to produce an acceptable level of thrust, and to take advantage of the higher thermodynamic efficiency available from the pulse detonation engine combustion cycle. This research thesis focused on improving and mapping fuel fraction delivery profiles for a valveless pulse detonation engine. T...

  16. A mathematical model for three dimensional detonation as pure gas-dynamic discontinuity

    OpenAIRE

    Escanciano, Jorge Yanez; Class, Andreas G.

    2012-01-01

    A model for three dimensional detonation is proposed based on the approximation that the detonation thickness is small compared to the characteristic scales of the fluid motion. In this framework detonations are treated as a modified hydrodynamic discontinuity. The altered Rankine-Hugoniot jump conditions take into account the internal structure of the detonation including the chemical reaction. The position of the discontinuity surface and the corresponding jump conditions are derived from f...

  17. Direct thrust force measurement of pulse detonation engine

    Science.gov (United States)

    Wahid, Mazlan Abdul; Faiz, M. Z. Ahmad; Saqr, Khalid M.

    2012-06-01

    In this paper we present the result of High-Speed Reacting Flow Laboratory (HiREF) pulse detonation engine (PDE) experimental study on direct thrust measurement. The thrust force generated by the repetitive detonation from a 50 mm inner diameter and 600 mm length tube was directly measured using load cell. Shchelkin spiral was used as an accelerator for the Deflagration to Detonation Transition (DDT) phenomenon. Propane-oxygen at stoichiometric condition was used as the combustible fuel-air mixture for the PDE. The PDE was operated at the operation frequency of 3Hz during the test. The amount of thrust force that was measured during the test reaching up to 70N. These values of thrust force were found to be fluctuating and its combustion phenomenon has been analyzed and discussed.

  18. Parametric Study of High Frequency Pulse Detonation Tubes

    Science.gov (United States)

    Cutler, Anderw D.

    2008-01-01

    This paper describes development of high frequency pulse detonation tubes similar to a small pulse detonation engine (PDE). A high-speed valve injects a charge of a mixture of fuel and air at rates of up to 1000 Hz into a constant area tube closed at one end. The reactants detonate in the tube and the products exit as a pulsed jet. High frequency pressure transducers are used to monitor the pressure fluctuations in the device and thrust is measured with a balance. The effects of injection frequency, fuel and air flow rates, tube length, and injection location are considered. Both H2 and C2H4 fuels are considered. Optimum (maximum specific thrust) fuel-air compositions and resonant frequencies are identified. Results are compared to PDE calculations. Design rules are postulated and applications to aerodynamic flow control and propulsion are discussed.

  19. Mathematical modeling of detonation initiation via flow cumulation effects

    Science.gov (United States)

    Semenov, I.; Utkin, P.; Akhmedyanov, I.

    2016-07-01

    The paper concerns two problems connected with the idea of gaseous detonation initiation via flow cumulation effects and convergence of relatively weak shock waves (SW). The first one is the three-dimensional (3D) numerical investigation of shock-to-detonation transition (SDT) in methane-air mixture in a tube with parabolic contraction followed by the tube section of narrow diameter and conical expansion. The second problem is the numerical study of the start-up of the model small-scale hydrogen electrochemical pulse detonation engine with the use of electrical discharge generating the toroidal SW. The investigation is performed by means of numerical simulation with the use of modern high-performance computing systems.

  20. On Possibility of Detonation Products Temperature Measurements of Emulsion Explosives

    Directory of Open Access Journals (Sweden)

    Silvestrov V. V.

    2014-10-01

    Full Text Available The new view on the structure of the radiance signal recorded by optical pyrometer and the preliminary results of brightness detonation temperature of the emulsion explosive are presented. The structure of an optical signal observed is typical for the heterogeneous explosives. First, there is the short temperature spike to 2500 ÷ 3300 K connecting with a formation of “hot spots” assembly that fire the matrix capable of exothermal reaction. Then the relaxation of radiance to equilibrium level is observed that corresponds to brightness temperature 1840 ÷ 2260 K of explosion products at detonation pressure 1 ÷ 11 GPa. Experimental results are compared with the calculations of other authors. The detonation temperature of the investigated explosive is measured for the first time.

  1. Gasdynamic characteristics of toroidal shock and detonation wave converging

    Institute of Scientific and Technical Information of China (English)

    TENG; Honghui; JIANG; Zonglin

    2005-01-01

    The modified CCW relation is applied to analyzing the shock, detonation wave converging and the role of chemical reactions in the process. Results indicate that the shock wave is strengthened faster than the detonation wave in the converging at the same initial Mach number. Euler equations implemented with a detailed chemical reaction model are solved to simulate toroidal shock and detonation wave converging. Gasdynamic characteristics of the converging are investigated, including wave interaction patterns, observable discrepancies and physical phenomena behind them. By comparing wave diffractions, converging processes and pressure evolutions in the focusing area, the different effects of chemical reactions on diffracting and converging processes are discussed and the analytic conclusion is demonstrated through the observation of numerical simulations.

  2. 33 CFR Appendix A to Part 154 - Guidelines for Detonation Flame Arresters

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Guidelines for Detonation Flame... Appendix A to Part 154—Guidelines for Detonation Flame Arresters This appendix contains the draft ASTM standard for detonation flame arresters. Devices meeting this standard will be accepted by the...

  3. Mechanisms of direct detonation initiation via thermal explosion of radiatively heated gas-particles layer

    Directory of Open Access Journals (Sweden)

    V.P. Efremov

    2015-01-01

    Full Text Available Conceptual approach of detonation wave direct initiation by external radiative heating of microparticles locally suspended in flammable gaseous mixture is proposed. Combustion waves and detonation initiation mechanisms in the congestion regions of microparticles heated by radiation are studied numerically. Necessary criteria on geometrical scales of gas-particles layer and spatial uniformity of particles distribution for successful detonation initiation are formulated.

  4. Deflagration-to-detonation transition (DDT) project. Semiannual report, June-November 1980

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, W.G. (ed.)

    1981-07-01

    Studies of the Deflagration-to-Detonation Transition (DDT) distance in detonators, performed during June through November 1980, are reported in detail. Accomplishments include development of small, safe detonators and of computer models of DDT, and development of methods to analyze impurities in CP.

  5. Numerical modeling of the combustion-detonation transition in a homogeneous combustible gas mixture

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, N.N.; Panfilov, I.I.

    1993-06-01

    A method is proposed whereby a unified model is used to study numerically the combustion and detonation in homogeneous gas mixtures, including transient processes, and to determine the conditions for the combustion-detonation transition. The method also makes it possible to investigate the unsteady regimes of detonation wave propagation. Results of calculations are presented for several examples. 34 refs.

  6. Mechanisms of direct detonation initiation via thermal explosion of radiatively heated gas-particles layer

    OpenAIRE

    V.P. Efremov; Ivanov, M. F.; Kiverin, A. D.; I.S. Yakovenko

    2015-01-01

    Conceptual approach of detonation wave direct initiation by external radiative heating of microparticles locally suspended in flammable gaseous mixture is proposed. Combustion waves and detonation initiation mechanisms in the congestion regions of microparticles heated by radiation are studied numerically. Necessary criteria on geometrical scales of gas-particles layer and spatial uniformity of particles distribution for successful detonation initiation are formulated.

  7. Benign Prostatic Hyperstatic Hyperplasia (BPH) (Beyond the Basics)

    Science.gov (United States)

    ... names for benign prostatic hyperplasia include benign prostatic hypertrophy, an enlarged prostate, and BPH. BPH occurs only ... prostatic hyperplasia" .) Alpha blockers — These medications relax the muscle of the prostate and bladder neck, which allows ...

  8. Initiation of detonation by impact on granular explosives

    International Nuclear Information System (INIS)

    A good number of experiments have shown up the particular behaviour of granular explosives when they are detonated by barrier transmitted shocks. Similar results can be obtained when the shock is induced by impact. In this case the pressure signal shape applied at the explosive is better known and both its intensity and duration can be varied. By using a mathematical model in which the law of chemical kinetics is a linear function of pressure, and different temperatures are used for solids and gases, it is possible to describe most of the behaviour of detonation initiation in solid granular explosives. (author)

  9. Estimation of the detonation cell size in gases

    Science.gov (United States)

    Kuchinskii, V. V.; Onosov, I. I.

    2011-06-01

    A simple method to calculate the parameters of a shock wave in a space between the shock wave front and the Chapman-Jouguet plane is considered. Solving a velocity equation, one can calculate the pressure, density, and temperature of the gas, as well as determine the size of a detonation region in a one-dimensional approximation. The dependences of the detonation region size on input parameters are derived. From these dependences, one can estimate the run of the same curves in the real situation.

  10. Quantification of uncertainties for application in detonation simulation

    Science.gov (United States)

    Zheng, Miao; Ma, Zhibo

    2016-06-01

    Numerical simulation has become an important means in designing detonation systems, and the quantification of its uncertainty is also necessary to reliability certification. As to quantifying the uncertainty, it is the most important to analyze how the uncertainties occur and develop, and how the simulations develop from benchmark models to new models. Based on the practical needs of engineering and the technology of verification & validation, a framework of QU(quantification of uncertainty) is brought forward in the case that simulation is used on detonation system for scientific prediction. An example is offered to describe the general idea of quantification of simulation uncertainties.

  11. Rotating Detonation Combustion: A Computational Study for Stationary Power Generation

    Science.gov (United States)

    Escobar, Sergio

    The increased availability of gaseous fossil fuels in The US has led to the substantial growth of stationary Gas Turbine (GT) usage for electrical power generation. In fact, from 2013 to 2104, out of the 11 Tera Watts-hour per day produced from fossil fuels, approximately 27% was generated through the combustion of natural gas in stationary GT. The thermodynamic efficiency for simple-cycle GT has increased from 20% to 40% during the last six decades, mainly due to research and development in the fields of combustion science, material science and machine design. However, additional improvements have become more costly and more difficult to obtain as technology is further refined. An alternative to improve GT thermal efficiency is the implementation of a combustion regime leading to pressure-gain; rather than pressure loss across the combustor. One concept being considered for such purpose is Rotating Detonation Combustion (RDC). RDC refers to a combustion regime in which a detonation wave propagates continuously in the azimuthal direction of a cylindrical annular chamber. In RDC, the fuel and oxidizer, injected from separated streams, are mixed near the injection plane and are then consumed by the detonation front traveling inside the annular gap of the combustion chamber. The detonation products then expand in the azimuthal and axial direction away from the detonation front and exit through the combustion chamber outlet. In the present study Computational Fluid Dynamics (CFD) is used to predict the performance of Rotating Detonation Combustion (RDC) at operating conditions relevant to GT applications. As part of this study, a modeling strategy for RDC simulations was developed. The validation of the model was performed using benchmark cases with different levels of complexity. First, 2D simulations of non-reactive shock tube and detonation tubes were performed. The numerical predictions that were obtained using different modeling parameters were compared with

  12. Characterization of Detonation Products of RSI-007 Explosive

    Science.gov (United States)

    Ager, Timothy; Neel, Christopher; Chhabildas, Lalit

    2011-06-01

    PDV and VISAR have been employed to characterize the detonation products of a production quality RSI-007 explosive. The explosive was part of an exploding foil initiator (EFI) detonator assembly in which the explosive was contained within a Kovar (Fe-Ni-Co alloy) cup. The free surface of the Kovar serves as the witness plate for the interferometry measurements. Detailed shock reverberations are recorded on the witness plate and the isentropic release path of the explosive is inferred though the velocity history. Two separate window materials are bonded to the Kovar cup in subsequent experiments and are used to further determine the release state in different pressure regimes. Presenter

  13. Towards Integrated Pulse Detonation Propulsion and MHD Power

    Science.gov (United States)

    Litchford, Ron J.; Thompson, Bryan R.; Lineberry, John T.

    1999-01-01

    The interest in pulse detonation engines (PDE) arises primarily from the advantages that accrue from the significant combustion pressure rise that is developed in the detonation process. Conventional rocket engines, for example, must obtain all of their compression from the turbopumps, while the PDE provides additional compression in the combustor. Thus PDE's are expected to achieve higher I(sub sp) than conventional rocket engines and to require smaller turbopumps. The increase in I(sub sp) and the decrease in turbopump capacity must be traded off against each other. Additional advantages include the ability to vary thrust level by adjusting the firing rate rather than throttling the flow through injector elements. The common conclusion derived from these aggregated performance attributes is that PDEs should result in engines which are smaller, lower in cost, and lighter in weight than conventional engines. Unfortunately, the analysis of PDEs is highly complex due to their unsteady operation and non-ideal processes. Although the feasibility of the basic PDE concept has been proven in several experimental and theoretical efforts, the implied performance improvements have yet to be convincingly demonstrated. Also, there are certain developmental issues affecting the practical application of pulse detonation propulsion systems which are yet to be fully resolved. Practical detonation combustion engines, for example, require a repetitive cycle of charge induction, mixing, initiation/propagation of the detonation wave, and expulsion/scavenging of the combustion product gases. Clearly, the performance and power density of such a device depends upon the maximum rate at which this cycle can be successfully implemented. In addition, the electrical energy required for direct detonation initiation can be significant, and a means for direct electrical power production is needed to achieve self-sustained engine operation. This work addresses the technological issues associated

  14. Single-Cycle Impulse from Detonation Tubes with Nozzles

    OpenAIRE

    Cooper, M; Shepherd, J. E.

    2008-01-01

    Experiments measuring the single-cycle impulse from detonation tubes with nozzles were conducted by hanging the tubes in a ballistic pendulum arrangement within a large tank. The detonation-tube nozzle and surrounding tank were initially filled with air between 1.4 and 100 kPa in pressure simulating high-altitude conditions. A stoichiometric ethylene–oxygen mixture at an initial pressure of 80 kPa filled the constant-diameter portion of the tube. Four diverging nozzles and six converging–dive...

  15. Process Investigation of Tube Expansion by Gas Detonation

    OpenAIRE

    Bach, F.-W.; Beerwald, C.; Brosius, A.; Gershteyn, G.; Hermes, M.; Kleiner, M.; Olivier, H.; M. Weber

    2006-01-01

    The present paper deals with the expansion of tubes by direct application of gas detonation waves, i.e. the gas is both pressure medium and energy source. After an introduction to gas detonation forming, measurements of the motion process and the internal pressures are presented. Results of free expansion and of forming into a die are thoroughly studied and compared to the results of quasi-static burst tests and hydroforming. Using pure aluminum Al99.5 and a medium strength alloy AlMgSi1, ...

  16. Vitamin D deficiency and benign paroxysmal positioning vertigo

    OpenAIRE

    Büki, Bela; Ecker, Michael; Jünger, Heinz; Lundberg, Yunxia Wang

    2012-01-01

    Benign paroxysmal positional vertigo is a common cause of disabling vertigo with a high rate of recurrence. Although connections between vitamin D deficiency and osteoporosis, as well as between osteoporosis and benign paroxysmal positional vertigo have been suggested respectively in the literature, we are not aware of any publication linking vitamin D and benign paroxysmal positional vertigo. As a hypothesis, we suggest that there is a relation between insufficient vitamin D level and benign...

  17. Benign Multicystic Mesothelioma in the Left Round Ligament: Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Bae, So Young; Yi, Boem Ha; Lee, Hae Kyung; Park, Seong Jin; Cho, Gyu Seok; Kwak, Jeong Ja [Soonchunhyang University Bucheon Hospital, Bucheon (Korea, Republic of)

    2010-02-15

    Benign multicystic mesothelioma is a rare mesothelial lesion that forms multicystic masses in the upper abdomen, pelvis, and retroperitoneum. Most cases have a benign course. We present the ultrasound and MR findings of benign multicystic mesothelioma in the left round ligament, which caused a left inguinal hernia in a 46-year-old woman.

  18. Characteristics of benign lymphoadenosis of oral mucosa

    Institute of Scientific and Technical Information of China (English)

    Shu-Xia Li; Shi-Feng Yu; Kai-Hua Sun

    2005-01-01

    AIM: To investigate the pathological characteristics and carcinogenesis mechanism of benign lymphoadenosis of oral mucosa (BLOM).METHODS: The expressions of Ki-67, CD34 and apoptosis were evaluated by immunohistochemical SP staining in 64 paraffin-embedded tissue samples. Of them, 9 were from BLOM with dysplasia, 15 from BLOM without dysplasia,15 from oral squamous cell carcinoma (OSCC), 15 from oral precancerosis, and 10 from normal tissues. Cell proliferation, apoptosis and angiogenesis of tissue samples were also analyzed.RESULTS: The expression of Ki-67 in BLOM with dysplasia,oral precancerosis and OSCC was significantly higher than in BLOM without dysplasia and normal mucosa. The microvascular density (MVD) in BLOM with and without dysplasia, oral precancerosis, and OSCC was significantly higher than in normal mucosa. Apoptosis in BLOM and oral precancerosis was significantly higher than in OSCC and normal mucosa.CONCLUSION: Benign lymphoadenosis of oral mucosa has potentialities of cancerization.

  19. Skeletal scintigraphy in benign and malignant disease

    International Nuclear Information System (INIS)

    This paper begins with a discussion of the technical factors in skeletal scintigraphy, including collimation, the use of three-phase bone scan, and single-photon emission computed tomography. Skeletal scintigraphy for benign conditions is commonly indicated for the patient presenting with pain (trauma, sports-related injury, posttraumatic pain syndrome, painful orthopedic prosthesis) and for the patient with abnormal laboratory test results (metabolic bone disease, Paget disease). For malignant conditions, the bone scan is useful in the evaluation of metastases in patients with extraosseous malignancies and primary bone tumors. The discussion addresses the various scan patterns seen in the more common tumors, such as prostate carcinoma, breast carcinoma, and lung carcinoma. Bone scintigraphy is an exquisitely sensitive modality. With some understanding of the techniques necessary for obtaining the optimal bone scan, and of the patterns that can be seen in various clinical conditions, the radiologist will find the bone scan a very specific tool for evaluating both benign and malignant diseases

  20. Benign nerve sheath tumor of stomach

    International Nuclear Information System (INIS)

    Gastrointestinal mesenchymal tumors are a group of tumors, which originate from the mesenchymal stem cells of the gastrointestinal tract. Gastric schwannoma is a very rare gastrointestinal mesenchymal tumor, which represents only 0.2% of all gastric tumors and 4% of all benign gastric neoplasms. We report a 55 years old lady who suffered from pain epigastrium, vomiting, occasionally with blood, loss of appetite and weight loss. Endoscopic examination showed a round submucosal tumor with a central ulceration along the greater curvature of the stomach. The pathological examination revealed a picture of spindle cell tumor. Immunohistochemical stain was strongly positive for S-100 protein stain, and non-reactive for CD34, CD117, consistent with benign nerve sheath tumor of stomach i.e. gastric schwannoma. (author)

  1. Benign solitary solid cold thyroid nodules

    DEFF Research Database (Denmark)

    Døssing, Helle; Bennedbaek, Finn Noe; Karstrup, Steen;

    2002-01-01

    PURPOSE: To evaluate the effects of ultrasonography (US)-guided interstitial laser photocoagulation (ILP) on the volume of benign solitary solid cold thyroid nodules and any nodule-related symptoms. MATERIALS AND METHODS: ILP was performed in 16 patients with normal thyroid function and a solid...... benign thyroid nodule. None of the patients had uptake on a radionuclide scan. Patients underwent one ILP session. A needle was positioned in the thyroid nodule with US guidance, and the laser fiber was placed in the lumen of the needle. Patients were treated for 287-1,200 seconds with an output power of...... 1-3 W. ILP was performed with continuous US guidance and terminated when the echogenic changes were stationary. Thyroid nodule volume and thyroid function were evaluated before and 1, 3, and 6 months after treatment. During the same period, 15 untreated patients (control group) were followed up to...

  2. Radiotherapy in benign uterine bleeding disorders

    International Nuclear Information System (INIS)

    Radiotherapy was earlier a method of choice for treatment of benign bleeding disorders (metropathia), especially in woman of high surgical risk. During the period 1912 to 1977 933 women with benign bleeding disorders were treated at Radiumhemmet with intracavitary brachytherapy or external irradiation or a combination of both. The result with regard to cure of the uterine bleedings was good (48%). Hormonal withdrawal symptoms after treatment were noted in 45% of the patients. In the long term follow up an increased risk of cardiovascular death was found in women treated before menopause. Malignant tumours occurred in 107 cases versus 90.2 expected. The estimated ovarian dose of ionizing radiation varied from 3.5 Gy to 6.0 Gy for the three standard techniques. Two women gave birth to a healthy child 4 and 5 years after intracavitary radium treatment. The estimated absorbed dose to the ovaries in these two women were 1 Gy and 4 Gy, respectively

  3. Endoscopic therapy of benign biliary strictures

    Institute of Scientific and Technical Information of China (English)

    Joel R Judah; Peter V Draganov

    2007-01-01

    Benign biliary strictures are being increasingly treated with endoscopic techniques. The benign nature of the stricture should be first confirmed in order to ensure appropriate therapy. Surgery has been the traditional treatment, but there is increasing desire for minimally invasive endoscopic therapy. At present, endoscopy has become the first line approach for the therapy of postliver transplant anastomotic strictures and distal (Bismuth Ⅰ and Ⅱ) post-operative strictures. Strictures related to chronic pancreatitis have proven more difficult to treat,and endoscopic therapy is reserved for patients who are not surgical candidates. The preferred endoscopic approach is aggressive treatment with gradual dilation of the stricture and insertion of multiple plastic stents. The use of uncovered self expandable metal stents should be discouraged due to poor long-term results. Treatment with covered metal stents or bioabsorbable stents warrants further evaluation. This area of therapeutic endoscopy provides an ongoing opportunity for fresh research and innovation.

  4. Stab Wound in the Skull Treated with a Medial Supraorbital Craniotomy Through an Incision in the Eyebrow-a Minimally Invasive Approach.

    Science.gov (United States)

    Araujo, João Luiz Vitorino; Ferraz, Vinicius Ricieri; Vilela, Denes; Sette, Marcelo

    2015-12-01

    The eyebrow incision associated with medial supraorbital craniotomy is a minimally invasive alternative approach to the lesions located in the medial anterior cranial fossa. The main advantages of the medial supraorbital craniotomy regarding frontolateral supraorbital craniotomy are the absence of manipulation of the temporal muscle, less risk of injury to the frontotemporal branch of the facial nerve and a more medial view of the anterior structures such as frontal sinus, olfatory groove and frontal lobe. We report a unique case of cranial stab wound in which a piece of the knife stayed in the frontal sinus and removal was performed using the medial supraorbital approach. There were no complications during surgery, the patient reported mild hypoesthesia in the left frontal region and was discharged on the 7th postoperative day. During follow-up after 2 months, good cosmetic result of the surgical wound and preserved sensitivity of the left frontal region were noted. PMID:26884664

  5. Desmoplastic infantile ganglioglioma: a questionably benign tumour

    International Nuclear Information System (INIS)

    Desmoplastic infantile ganglioglioma is a rare intracranial tumour of childhood that involves the cerebral cortex and the leptomeninges. We report two patients with desmoplastic infantile gangliogliomas and multiple cerebrospinal metastases. To our knowledge, only two similar cases have been reported in the published literature. Pathologically, this rare intracranial tumour shows glial and ganglionic differentiation, accompanied by an extreme desmoplastic reaction. These are low-grade neoplasms that are questionably benign. Copyright (2005) Blackwell Science Pty Ltd

  6. Case report: Benign porta hepatic schwannoma

    International Nuclear Information System (INIS)

    Schwannoma is a myelin sheath tumor that can occur almost anywhere in the body. The most common locations are the central nervous system, extremities, neck, mediastinum and retroperitoneum. Benign schwannomas in the porta hepatis are extremely rare and radiologically are diagnosed as either enlarged lymph nodes or bowel masses, such as gastrointestinal stromal tumors. In this location they usually produce symptoms by compressing adjacent structures and often present with obstructive jaundice. The preoperative diagnosis can be extremely difficult

  7. Benign Intracranial Hypertension: A Diagnostic Dilemma

    OpenAIRE

    Shaw, Gary Y.; Stephanie K. Million

    2012-01-01

    Benign intracranial hypertension (BIH) (also known as pseudotumor cerebri and empty sella syndrome) remains a diagnostic challenge to most physicians. The modified Dandy criteria consist of, the classic findings of headache, pulsatile tinnitus, papilledema, and elevated cerebrospinal fluid (CSF) pressure, however, these are rarely collectively present in any one patient. Furthermore, these findings can wax and wane over time. Due to the nature of this disease, both signs and symptoms may be i...

  8. Percutaneous treatment of benign bile duct strictures

    Energy Technology Data Exchange (ETDEWEB)

    Koecher, Martin [Department of Radiology, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic)]. E-mail: martin.kocher@seznam.cz; Cerna, Marie [Department of Radiology, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic); Havlik, Roman [Department of Surgery, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic); Kral, Vladimir [Department of Surgery, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic); Gryga, Adolf [Department of Surgery, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic); Duda, Miloslav [Department of Surgery, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic)

    2007-05-15

    Purpose: To evaluate long-term results of treatment of benign bile duct strictures. Materials and methods: From February 1994 to November 2005, 21 patients (9 men, 12 women) with median age of 50.6 years (range 27-77 years) were indicated to percutaneous treatment of benign bile duct stricture. Stricture of hepatic ducts junction resulting from thermic injury during laparoscopic cholecystectomy was indication for treatment in one patient, stricture of hepaticojejunostomy was indication for treatment in all other patients. Clinical symptoms (obstructive jaundice, anicteric cholestasis, cholangitis or biliary cirrhosis) have appeared from 3 months to 12 years after surgery. Results: Initial internal/external biliary drainage was successful in 20 patients out of 21. These 20 patients after successful initial drainage were treated by balloon dilatation and long-term internal/external drainage. Sixteen patients were symptoms free during the follow-up. The relapse of clinical symptoms has appeared in four patients 9, 12, 14 and 24 months after treatment. One year primary clinical success rate of treatment for benign bile duct stricture was 94%. Additional two patients are symptoms free after redilatation (15 and 45 months). One patient is still in treatment, one patient died during secondary treatment period without interrelation with biliary intervention. The secondary clinical success rate is 100%. Conclusion: Benign bile duct strictures of hepatic ducts junction or biliary-enteric anastomosis are difficult to treat surgically and endoscopically inaccessible. Percutaneous treatment by balloon dilatation and long-term internal/external drainage is feasible in the majority of these patients. It is minimally invasive, safe and effective.

  9. Large Penile Mass With Unusual Benign Histopathology.

    Science.gov (United States)

    Johnson, Nate; Voznesensky, Maria; VerLee, Graham

    2015-09-01

    Pseudoepitheliomatous hyperplasia is an extremely rare condition presenting as a lesion on the glans penis in older men. Physical exam without biopsy cannot differentiate malignant from nonmalignant growth. We report a case of large penile mass in an elderly male with a history of lichen sclerosis, highly suspicious for malignancy. Subsequent surgical removal and biopsy demonstrated pseudoepitheliomatous hyperplasia, an unusual benign histopathologic diagnosis with unclear prognosis. We review the literature and discuss options for treatment and surveillance. PMID:26793536

  10. Large Penile Mass With Unusual Benign Histopathology

    Directory of Open Access Journals (Sweden)

    Nate Johnson

    2015-09-01

    Full Text Available Pseudoepitheliomatous hyperplasia is an extremely rare condition presenting as a lesion on the glans penis in older men. Physical exam without biopsy cannot differentiate malignant from nonmalignant growth. We report a case of large penile mass in an elderly male with a history of lichen sclerosis, highly suspicious for malignancy. Subsequent surgical removal and biopsy demonstrated pseudoepitheliomatous hyperplasia, an unusual benign histopathologic diagnosis with unclear prognosis. We review the literature and discuss options for treatment and surveillance.

  11. Surgical therapy of benign pineal tumors

    International Nuclear Information System (INIS)

    Currently, there is no way that the author knows to satisfactorily distinguish the benign lesions from their malignant cousins without a shadow of doubt. This includes preoperative evaluation of the clinical history, biological markers in serum and CSF, CT scans with and without contrast in various projections including the horizontal, coronal and sagittal cuts, and arteriography. Because the author has personally encountered difficulty in precisely diagnosing these tumors at routine light microscopy, especially when fragments are small, he has a personal aversion to the technique of diagnosis which enlists the use of a stereotactically placed biopsy needle. The author feels that virtually all of the pineal tumors require surgical exposure and sufficient tissue removal to ensure an accurate histological diagnosis. With experience, the author believes the surgeon can tell as he exposes the posterior and lateral aspects of these tumors whether or not they are encapsulated and therefore potentially resectable. This anatomical variation may be identified prior to operative intervention by an arteriogram especially with injection of large quantities of dye into the carotid system. With the advent of the CUSA (Cavitron Lasersonics, Cooper Medical Device Corporation, Stamford, CT), the author has used this instrument with increased facility and benefit in the removal of benign relatively avascular tumors of the pineal region. This instrument is ideal in coring out the interior of the tumor while creating little displacement of the tumor capsule. Some of the benign tumors, especially the meningiomas may be partially or heavily calcified and this instrument exhibits particular usefulness in these cases

  12. A study of benign adnexal masses

    Directory of Open Access Journals (Sweden)

    Jayasree Manivasakan

    2012-12-01

    Full Text Available Background: To study the relationship between age, symptoms, ultrasound findings, size and histological type of benign adnexal masses. Methods: Clinical records were retrieved of women who had surgical management for adnexal tumors in the study period, i.e. from January 2007 to December 2010 at Sri Manakula Vinayagar Medical College and Hospital, Puducherry. Results: There were 112 cases of ovarian tumors and tumor like lesions. 70.5% were diagnosed as ovarian tumors, 12.5% were functional cysts, 10.7% were paraovarian and paratubal cysts, 6.25% were hemorrhagic infarct where histopathology could not be reported. The age of the patient ranged from 11 to 70 years. Most of the patients (70.5% presented with abdominal pain either acute or chronic. Serous cystadenoma was the most common reported ovarian tumor (59.5% followed by mucinous cystadenoma (20% and mature cystic teratoma (14%. The cystic tumors were either functional cysts or benign tumors. Conclusions: The commonest tumor was surface epithelial tumor. Serous cystadenoma was the most common benign tumor. Serous and mucinous tumors occurred equally on both sides. The accuracy of preoperative ultrasound was higher in dermoid cysts followed by endometriotic cysts. [Int J Reprod Contracept Obstet Gynecol 2012; 1(1.000: 12-16

  13. Environmentally benign silicon solar cell manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Tsuo, Y.S. [National Renewable Energy Lab., Golden, CO (United States); Gee, J.M. [Sandia National Labs., Albuquerque, NM (United States); Menna, P. [National Agency for New Technologies Energy and Environment, Portici (Italy); Strebkov, D.S.; Pinov, A.; Zadde, V. [Intersolarcenter, Moscow (Russian Federation)

    1998-09-01

    The manufacturing of silicon devices--from polysilicon production, crystal growth, ingot slicing, wafer cleaning, device processing, to encapsulation--requires many steps that are energy intensive and use large amounts of water and toxic chemicals. In the past two years, the silicon integrated-circuit (IC) industry has initiated several programs to promote environmentally benign manufacturing, i.e., manufacturing practices that recover, recycle, and reuse materials resources with a minimal consumption of energy. Crystalline-silicon solar photovoltaic (PV) modules, which accounted for 87% of the worldwide module shipments in 1997, are large-area devices with many manufacturing steps similar to those used in the IC industry. Obviously, there are significant opportunities for the PV industry to implement more environmentally benign manufacturing approaches. Such approaches often have the potential for significant cost reduction by reducing energy use and/or the purchase volume of new chemicals and by cutting the amount of used chemicals that must be discarded. This paper will review recent accomplishments of the IC industry initiatives and discuss new processes for environmentally benign silicon solar-cell manufacturing.

  14. Asymptotic Solutions of Detonation Propagation in a 2D Circular Arc.

    Science.gov (United States)

    Short, Mark; Meyer, Chad; Quirk, James

    2015-11-01

    The large pressure of the product gas generated by detonating high explosives causes lateral motion of the explosive at the material interface between the explosive and its confinement. In turn, this leads to streamline divergence and curvature of the detonation front (typically in a divergent fashion). The propagation of a detonation front in a given geometry depends on the amount of curvature generated. Here we describe an asymptotic analysis of detonation propagation in a 2D circular arc, examining dependencies of the motion on the size of the inner and outer arc radii, and the relation between the detonation velocity and curvature for different types of explosive.

  15. Cellular Structure and Oscillating Behavior of PBX Detonations

    Science.gov (United States)

    Plaksin, Igor; Rodrigues, Luis; Mendes, Ricardo; Plaksin, Svyatoslav; Ferreira, Claudia; Fernandes, Eduardo

    2015-06-01

    Efforts are aimed on experimental study of reaction localization/instabilities manifested in detonation reaction zone (DRZ) of PBXs at micro-, meso- and macro-scale. At micro- and meso-scale levels, leading role of kinetic nonequilibrium in reaction localizations onset was established in experiments with single beta-HMX crystals-in-binder subjected to 20 GPa-shock and PBX detonation. Reaction localizations and further ejecta formation were spatially resolved by 96-channel optical analyzer at simultaneous recording reaction light and stress field around crystal. Spatially resolved measurements reveal fundamental role of shear-strain in triggering initiation chemistry. At macro-scale level, formation of the cell-structures and oscillating detonation regimes revealed in HMX- and RDX-based PBXs at wide variation of grain-sizes, wt. % filler/binder, residual micro-voids and binder nature. Emphasizes placed on effect of DRZ-induced radiation upon oscillating regimes of detonation front motion. Work was supported by the ONR and ONR Global Grants N00014-12-1-0477 and N62909-12-1-7131 with Drs. Clifford Bedford and John Zimmerman Program Managers.

  16. Calcium-Rich Gap Transients: Tidal Detonations of White Dwarfs?

    CERN Document Server

    Sell, P H; Kotak, R; Knigge, C; Sand, D J

    2015-01-01

    We hypothesize that at least some of the recently discovered class of calcium-rich gap transients are tidal detonation events of white dwarfs (WDs) by black holes (BHs) or possibly neutron stars. We show that the properties of the calcium-rich gap transients agree well with the predictions of the tidal detonation model. Under the predictions of this model, we use a follow-up X-ray observation of one of these transients, SN 2012hn, to place weak upper limits on the detonator mass of this system that include all intermediate-mass BHs (IMBHs). As these transients are preferentially in the stellar haloes of galaxies, we discuss the possibility that these transients are tidal detonations of WDs caused by random flyby encounters with IMBHs in dwarf galaxies or globular clusters. This possibility has been already suggested in the literature but without connection to the calcium-rich gap transients. In order for the random flyby cross-section to be high enough, these events would have to be occurring inside these den...

  17. HERMES: A Model to Describe Deformation, Burning, Explosion, and Detonation

    Energy Technology Data Exchange (ETDEWEB)

    Reaugh, J E

    2011-11-22

    HERMES (High Explosive Response to MEchanical Stimulus) was developed to fill the need for a model to describe an explosive response of the type described as BVR (Burn to Violent Response) or HEVR (High Explosive Violent Response). Characteristically this response leaves a substantial amount of explosive unconsumed, the time to reaction is long, and the peak pressure developed is low. In contrast, detonations characteristically consume all explosive present, the time to reaction is short, and peak pressures are high. However, most of the previous models to describe explosive response were models for detonation. The earliest models to describe the response of explosives to mechanical stimulus in computer simulations were applied to intentional detonation (performance) of nearly ideal explosives. In this case, an ideal explosive is one with a vanishingly small reaction zone. A detonation is supersonic with respect to the undetonated explosive (reactant). The reactant cannot respond to the pressure of the detonation before the detonation front arrives, so the precise compressibility of the reactant does not matter. Further, the mesh sizes that were practical for the computer resources then available were large with respect to the reaction zone. As a result, methods then used to model detonations, known as {beta}-burn or program burn, were not intended to resolve the structure of the reaction zone. Instead, these methods spread the detonation front over a few finite-difference zones, in the same spirit that artificial viscosity is used to spread the shock front in inert materials over a few finite-difference zones. These methods are still widely used when the structure of the reaction zone and the build-up to detonation are unimportant. Later detonation models resolved the reaction zone. These models were applied both to performance, particularly as it is affected by the size of the charge, and to situations in which the stimulus was less than that needed for reliable

  18. Using embedded fibers to measure explosive detonation velocities

    Energy Technology Data Exchange (ETDEWEB)

    Podsednik, Jason W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Parks, Shawn Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Navarro, Rudolfo J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2012-07-01

    Single-mode fibers were cleverly embedded into fixtures holding nitromethane, and used in conjunction with a photonic Doppler velocimeter (PDV) to measure the associated detonation velocity. These measurements have aided us in our understanding of energetic materials and enhanced our diagnostic capabilities.

  19. Detonation and combustion of explosives: A selected bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Dobratz, B. [comp.

    1998-08-01

    This bibliography consists of citations pertinent to the subjects of combustion and detonation of energetic materials, especially, but not exclusively, of secondary solid high explosives. These references were selected from abstracting sources, conference proceedings, reviews, and also individual works. The entries are arranged alphabetically by first author and numbered sequentially. A keyword index is appended.

  20. Detonation equation of state at LLNL, 1995. Revision 3

    Energy Technology Data Exchange (ETDEWEB)

    Souers, P.C.; Wu, B.; Haselman, L.C. Jr.

    1996-02-01

    JWL`s and 1-D Look-up tables are shown to work for ``one-track`` experiments like cylinder shots and the expanding sphere. They fail for ``many-track`` experiments like the compressed sphere. As long as the one-track experiment has dimensions larger than the explosive`s reaction zone and the explosive is near-ideal, a general JWL with R{sub 1} = 4.5 and R{sub 2} = 1.5 can be constructed, with both {omega} and E{sub o} being calculated from thermochemical codes. These general JWL`s allow comparison between various explosives plus recalculation of the JWL for different densities. The Bigplate experiment complements the cylinder test by providing continuous oblique angles of shock incidence from 0{degrees} to 70{degrees}. Explosive reaction zone lengths are determined from metal plate thicknesses, extrapolated run-to-detonation distances, radius size effects and detonation front curvature. Simple theories of the cylinder test, Bigplate, the cylinder size effect and detonation front curvature are given. The detonation front lag at the cylinder edge is shown to be proportional to the half-power of the reaction zone length. By calibrating for wall blow-out, a full set of reaction zone lengths from PETN to ANFO are obtained. The 1800--2100 K freezing effect is shown to be caused by rapid cooling of the product gases. Compiled comparative data for about 80 explosives is listed. Ten Chapters plus an Appendix.

  1. Conditions For Successful Helium Detonations In Astrophysical Environments

    CERN Document Server

    Holcomb, Cole; De Colle, Fabio; Ramirez-Ruiz, Enrico

    2013-01-01

    Several models for type Ia-like supernovae events rely on the production of a self-sustained detonation powered by nuclear reactions.In the absence of hydrogen, the fuel that powers these detonations typically consists of either pure helium (He) or a mixture of carbon and oxygen (C/O). Studies that systematically determine the conditions required to initiate detonations in C/O material exist, but until now no analogous investigation of degenerate He matter has been conducted. We perform one-dimensional reactive hydrodynamical simulations at a variety of initial density and temperature combinations and find critical length scales for the initiation of He detonations that range between 1 -- $10^{10}$ cm. These sizes are consistently smaller than the corresponding Chapman-Jouguet (CJ) length scales by a factor of ~100, providing opportunities for thermonuclear explosions in a wider range of low mass white dwarfs (WDs) than previously thought possible. We find that virialized WDs with as little mass as 0.24 $M_\\o...

  2. Wave dynamic processes in cellular detonation reflection from wedges

    Institute of Scientific and Technical Information of China (English)

    Zongmin Hu; Zonglin Jiang

    2007-01-01

    When the cell width of the incident deto-nation wave (IDW) is comparable to or larger than theMach stem height,self-similarity will fail during IDWreflection from a wedge surface.In this paper,the det-onation reflection from wedges is investigated for thewave dynamic processes occurring in the wave front,including transverse shock motion and detonation cellvariations behind the Mach stem.A detailed reactionmodel is implemented to simulate two-dimensional cel-lular detonations in stoichiometric mixtures of H2/O2diluted by Argon.The numerical results show that thetransverse waves,which cross the triple point trajec-tory of Mach reflection,travel along the Mach stem andreflect back from the wedge surface,control the size ofthe cells in the region swept by the Mach stem.It is theenergy carried by these transverse waves that sustainsthe triple-wave-collision with a higher frequency withinthe over-driven Mach stem.In some cases,local wavedynamic processes and wave structures play a dominantrole in determining the pattern of cellular record,lead-ing to the fact that the cellular patterns after the Machstem exhibit some peculiar modes.

  3. Simulations of a Detonation Wave in Transverse Magnetic Fields

    Science.gov (United States)

    Cole, Lord; Karagozian, Ann; Cambier, Jean-Luc

    2010-11-01

    Numerical simulations of magneto-hydrodynamic (MHD) effects on detonation wave structures are performed, with applications to flow control and MHD power extraction in Pulse Detonation Engines (PDE) and their design variations. In contrast to prior studies of MHD interactions in PDEs,ootnotetextCambier, et al., AIAA-2008-4688 the effects of the finite relaxation length scale for ionization on the stability of the detonation wave are examined. Depending on the coupling parameters, the magnetic field can quench the detonation and effectively act as a barrier to its propagation. Conversely, an applied transient magnetic field can exert a force on a pre-ionized gas and accelerate it. The dynamics are subject to non-linear effects; a propagating transverse magnetic field will initially exert a small force if the gas has a low conductivity and the magnetic Reynolds number (Rem) is low. Nevertheless, the gas accelerated by the "piston" action of the field can pre-heat the ambient gas and increase its conductivity. As the wave progresses, Rem increases and the magnetic field becomes increasingly effective. The dynamics of this process are examined in detail with a high-order shock-capturing method and full kinetics of combustion and ionization. The complex chemical kinetics calculations are ported onto a GPU using the CUDA language, and computational performance is compared with standard CPU-based computations.

  4. Microenergetics: Combustion and Detonation at Sub-Millimeter Scales

    Science.gov (United States)

    Tappan, Alexander S.

    2007-06-01

    At Sandia National Laboratories, we have coined the term ``microenergetics'' to describe sub-millimeter energetic material studies aimed at gaining knowledge of combustion and detonation behavior at the mesoscale.[1] Our approach is to apply technologies developed by the microelectronics industry to fabricate test samples with well-defined geometries. Substrates have been fabricated from materials such as silicon and ceramics, with channels to contain the energetic material. Energetic materials have been loaded into the channels, either as powders, femtosecond laser-micromachined pellets, or as vapor-deposited films. Ignition of the samples has been achieved by simple hotwires, integrated semiconductor bridges, and also by lasers. Additionally, grain-scale patterning has been performed on explosive films using both oxygen plasma etching and femtosecond laser micromachining.[2] We have demonstrated simple work functions in microenergetic devices, such as piston motion,[1] which is also a relevant diagnostic to examine combustion properties. Detonation has been achieved in deposited explosive films, recorded by high-speed photography.[3] A review of progress on manufacturing and testing will be presented, as well as historical perspectives and future directions. [1] A. S. Tappan, et al., 12th International Detonation Symposium (San Diego, CA, 2002). [2] A. S. Tappan, et al., 36th International Annual Conference of ICT, combined with 32nd International Pyrotechnics Seminar (Karlsruhe Federal Republic of Germany, 2005). [3] A. S. Tappan, et al., 13th International Detonation Symposium (Norfolk, VA, 2006).

  5. Experimental Study of a Pulse Detonation Engine Driven Ejector

    Science.gov (United States)

    Santoro, Robert J.; Pal, Sibtosh; Shehadeh, R.; Saretto, S.; Lee, S.-Y.

    2005-01-01

    Results of an experimental effort on pulse detonation driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE)/ejector setup that was specifically designed for the study. The results of various experiments designed to probe different aspects of the PDE/ejector setup are reported. The baseline PDE was operated using ethylene (C2H4) as the fuel and an oxygen/nitrogen (O2 + N2) mixture at an equivalence ratio of one. The PDE only experiments included propellant mixture characterization using a laser absorption technique, high fidelity thrust measurements using an integrated spring-damper system, and shadowgraph imaging of the detonation/shock wave structure emanating from the tube. The baseline PDE thrust measurement results are in excellent agreement with experimental and modeling results reported in the literature. These PDE setup results were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups with constant diameter ejector tubes and various detonation tube/ejector tube overlap distances. The results show that for the geometries studied here, a maximum thrust augmentation of 24% is achieved. Further increases are possible by tailoring the ejector geometry based on CFD predictions conducted elsewhere. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

  6. Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector

    Science.gov (United States)

    Santoro, Robert J.; Pal, Sibtosh

    2005-01-01

    Results of an experimental effort on pulse detonation driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE)/ejector setup that was specifically designed for the study and operated at frequencies up to 50 Hz. The results of various experiments designed to probe different aspects of the PDE/ejector setup are reported. The baseline PDE was operated using ethylene (C2H4) as the fuel and an oxygen/nitrogen O2 + N2) mixture at an equivalence ratio of one. The PDE only experiments included propellant mixture characterization using a laser absorption technique, high fidelity thrust measurements using an integrated spring-damper system, and shadowgraph imaging of the detonation/shock wave structure emanating from the tube. The baseline PDE thrust measurement results at each desired frequency agree with experimental and modeling results reported in the literature. These PDE setup results were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups with constant diameter ejector tubes and various ejector lengths, the radius of curvature for the ejector inlets and various detonation tube/ejector tube overlap distances. For the studied experimental matrix, the results showed a maximum thrust augmentation of 106% at an operational frequency of 30 Hz. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

  7. Experimental Investigation on Performance of Pulse Detonation Rocket Engine Model

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; FAN Wei; YAN Chuan-jun; HU Cheng-qi; YE Bin

    2007-01-01

    The PDRE test model used in these experiments utilized kerosene as the fuel, oxygen as oxidizer, and nitrogen as purge gas. The solenoid valves were employed to control intermittent supplies of kerosene, oxygen and purge gas. PDRE test model was 50 mm in inner diameter by 1.2 m long. The DDT (defiagration to detonation transition) enhancement device Shchelkin spiral was used in the test model.The effects of detonation frequency on its time-averaged thrust and specific impulse were experimentally investigated. The obtained results showes that the time-averaged thrust of PDRE test model was approximately proportional to the detonation frequency. For the detonation frequency 20 Hz, the time-averaged thrust was around 107 N, and the specific impulse was around 125 s. The nozzle experiments were conducted using PDRE test model with three traditional nozzles. The experimental results obtained demonstrated that all of those nozzles could augment the thrust and specific impulse. Among those three nozzles, the convergent nozzle had the largest increased augmentation, which was approximately 18%, under the specific condition of the experiment.

  8. Project Rio Blanco: detonation related activities. Final report

    International Nuclear Information System (INIS)

    Project Rio Blanco is described in relation to detonation, its history, execution, and results. Topics discussed include generalized site activities, emplacement well, explosive services and operations, operational safety, environmental protection program, seismic effects and damage claims, and add-on programs. (U.S.)

  9. A thermochemically derived global reaction mechanism for detonation application

    Science.gov (United States)

    Zhu, Y.; Yang, J.; Sun, M.

    2012-07-01

    A 4-species 4-step global reaction mechanism for detonation calculations is derived from detailed chemistry through thermochemical approach. Reaction species involved in the mechanism and their corresponding molecular weight and enthalpy data are derived from the real equilibrium properties. By substituting these global species into the results of constant volume explosion and examining the evolution process of these global species under varied conditions, reaction paths and corresponding rates are summarized and formulated. The proposed mechanism is first validated to the original chemistry through calculations of the CJ detonation wave, adiabatic constant volume explosion, and the steady reaction structure after a strong shock wave. Good agreement in both reaction scales and averaged thermodynamic properties has been achieved. Two sets of reaction rates based on different detailed chemistry are then examined and applied for numerical simulations of two-dimensional cellular detonations. Preliminary results and a brief comparison between the two mechanisms are presented. The proposed global mechanism is found to be economic in computation and also competent in description of the overall characteristics of detonation wave. Though only stoichiometric acetylene-oxygen mixture is investigated in this study, the method to derive such a global reaction mechanism possesses a certain generality for premixed reactions of most lean hydrocarbon mixtures.

  10. Exhaust Gas Emissions from a Rotating Detonation-wave Engine

    Science.gov (United States)

    Kailasanath, Kazhikathra; Schwer, Douglas

    2015-11-01

    Rotating detonation-wave engines (RDE) are a form of continuous detonation-wave engines. They potentially provide further gains in performance than an intermittent or pulsed detonation-wave engine (PDE). The overall flow field in an idealized RDE, primarily consisting of two concentric cylinders, has been discussed in previous meetings. Because of the high pressures involved and the lack of adequate reaction mechanisms for this regime, previous simulations have typically used simplified chemistry models. However, understanding the exhaust species concentrations in propulsion devices is important for both performance considerations as well as estimating pollutant emissions. Progress towards addressing this need will be discussed in this talk. In this approach, an induction parameter model is used for simulating the detonation but a more detailed finite-chemistry model including NOx chemistry is used in the expansion flow region, where the pressures are lower and the uncertainties in the chemistry model are greatly reduced. Results show that overall radical concentrations in the exhaust flow are substantially lower than from earlier predictions with simplified models. The performance of a baseline hydrogen/air RDE increased from 4940 s to 5000 s with the expansion flow chemistry, due to recombination of radicals and more production of H2O, resulting in additional heat release. Work sponsored by the Office of Naval Research.

  11. Computer simulation of initiation of detonation by shock focusing

    International Nuclear Information System (INIS)

    Failure of containment and essential equipment due to post-accident hydrogen combustion is recognized as a potential safety concern. One of the hazards posed by hydrogen combustion is the possibility of a transition to detonation resulting from flame acceleration. It has been demonstrated that the collision of the leading shock wave associated with an accelerated flame with obstacles along its path can create local hot spots and trigger onset of detonation. The objective of this paper is, through computer simulation, to determine the critical conditions required for onset of detonation and to establish the criteria for transition to detonation in tubes filled with various types of obstacles. The simulations described in this paper model the initiation of detonation resulting from a collision of a shock wave with a hemispherical cup. Three different configurations were used to examine formation of local hot spots by shock focusing. The first configuration was a 6 cm-diameter hemispherical cup located at the closed end of the tube (also 6 cm in diameter). Hemispherical cups were used in the present study because their 3-dimensional structure produces strong shock focusing effects. This configuration also allows us to simulate a 3-D phenomenon with a 2-D computer code. The second case was similar to the first configuration except that a 2 cm shoulder was added to the side of the cup. The third configuration was a 2 cm-diameter orifice placed along the centre of the tube. This configuration represents the limiting case in which the effects created by the curvature of the cup are removed in the shock focusing process. The gas mixture used in the simulation was a stoichiometric hydrogen-oxygen mixture at an initial pressure of 13.2 kPa and a temperature of 300 K. The critical conditions in terms of incident shock Mach numbers were determined for these three configurations. These critical conditions for onset of detonation agree with experimental observations. The present

  12. Haemocompatibility Of Non-Functionalized And Plasmachemical Functionalized Detonation Nanodiamond Particles

    Directory of Open Access Journals (Sweden)

    Mitura K.

    2015-09-01

    Full Text Available The purpose of this paper is to present the innovative design of microwave plasma system for modification of detonation nanodiamond particles (DNP using a special rotating drum placed inside the reactor. Nanodiamond particles manufactured by detonation method reveal the biological activity depending on surface functionalization. Plasmachemical modification of detonation nanodiamond particles gives the possibility of controlling surface of nanodiamonds particles in biological tests. In this paper we would like to compare detonation nanodiamond (the grain sizes from 2 to 5 nm with modified detonation nanodiamond in rotary reactor chamber, by microwave plasma activated chemical vapour deposition (MW PACVD method in materials research (Raman and FT-IR spectroscopy and in vitro examinations with full of human blood. The results indicate haemocompatibility of non-modified detonation nanodiamond and modified nanodiamond by MW PACVD method in rotary reactor chamber (modified ND-3 and the presence of haemolysis in commercial detonation nanodiamond.

  13. The Initiation and Propagation of Helium Detonations in White Dwarf Envelopes

    CERN Document Server

    Shen, Ken J

    2014-01-01

    Detonations in helium-rich envelopes surrounding white dwarfs have garnered attention as triggers of faint thermonuclear ".Ia" supernovae and double detonation Type Ia supernovae. However, recent studies have found that the minimum size of a hotspot that can lead to a helium detonation is comparable to, or even larger than, the white dwarf's pressure scale height, casting doubt on the successful ignition of helium detonations in these systems. In this paper, we examine the previously neglected effects of C/O pollution and a full nuclear reaction network, and we consider hotspots with spatially constant pressure in addition to constant density hotspots. We find that the inclusion of these effects significantly decreases the minimum hotspot size for helium-rich detonation ignition, making detonations far more plausible during turbulent shell convection or during double white dwarf mergers. The increase in burning rate also decreases the minimum shell mass in which a helium detonation can successfully propagate ...

  14. Initiation of unconfined gas detonations in hydrocarbon-air mixtures by a sympathetic mechanism

    International Nuclear Information System (INIS)

    The considered investigation is concerned with the study of the factors which influence detonation propagation in a gas of heterogeneous composition. The conducted experiments assess the ability of a blast wave, emerging from a donor gas detonation and crossing an air gap, to initiate detonation in a second, similar, acceptor gas mixture. Stoichiometric mixtures of both ethylene-air and propane-air are found to exhibit 'sympathetic' gas detonation only across small air gaps. Conditions critical to sympathetic gas detonation agree with predictions of a simple theory taking account of the net shock decay occurring across two acoustic interfaces bounded by an air gap. Sympathetic detonation occurs only if the strength of the shock upon entering the acceptor exceeds a threshold value for the particular gas mixture. Reinitiation of detonation is not satisfactorily explained by planar blast wave decay and autoignition considerations

  15. Investigations of pipeline reactions to detonations of radiolysis gas

    International Nuclear Information System (INIS)

    As a case of damage in a head spray cooling piping of a boiling-water reactor showed, detonations of radiolysis gas in safety-relevant tubes of nuclear power plants cannot be excluded in all cases. Radiolysis gas is a mixture of gaseous hydrogen and oxygen in stoichiometric ratio which is generated by dissociation of water under the influence of gamma and neutron radiation. Within the scope of a research project funded by the Federal Ministry of Economics and Technology (BMWi) the basis for the assessment of the related risk potential for plant operation shall, among others, be provided. Due to the high-rate response of the pipe to the detonation, multiple longitudinal cracks and fragmentation can occur. Detonation tests and numerical evaluations are performed to simulate detonations of radiolysis gas in thin-walled pipes. The radiolysis gas is simulated by mixing hydrogen and oxygen from gas bottles. Pipes made of austenitic steel with the nominal dimensions of OD x t = 114,30 mm x 6,02 mm are used for the tests. The internal pressure is 70 bar in all cases. In different tests, which are carried out at room temperature, the ratio of radiolysis gas in the pipe is varied and for the simulation of steam nitrogen is used as another filling medium. Next to the results of three detonation tests with a radiolysis gas ratio of 60% and 80% the results of tests, carried out for the experimental evaluation of the radiolysis gas reactions, with thick-walled vessels are presented. (orig.)

  16. Three-dimensional cellular structure of detonations in suspensions of aluminium particles

    Science.gov (United States)

    Khasainov, B.; Virot, F.; Veyssière, B.

    2013-05-01

    Recently, we have used scarce available data on the detonation cell size in suspensions of aluminium particles in air and oxygen to adjust the kinetic parameters of our two-phase model of detonations in these mixtures. The calculated detonation cell width was derived by means of two-dimensional (2D) unsteady simulations using an assumption of cylindrical symmetry of the flow in the tube. However, in reality, the detonation cells are three-dimensional (3D). In this work, we have applied the same detonation model which is based on the continuous mechanics of two-phase flows, for 3D numerical simulations of cellular detonation structures in aluminium particle suspensions in oxygen. Reasonable agreement on the detonation cell width was obtained with the aforementioned 2D results. The range of tube diameters where detonations in { Al/O}_2 mixture at a given particle size and concentration would propagate in the spinning mode has been estimated (these results make a complement to our previous analysis of spinning detonations in Al/air mixtures). Coupling these results with the dependencies of detonation cell size on the mean particle diameter is of great interest for the understanding of fundamental mechanisms of detonation propagation in solid particle suspensions in gas and can help to better guide the experimental studies of detonations in aluminium suspensions. It is shown that the part of detonation wave energy used for transverse kinetic energy of both gas and particles is quite small, which explains why the propagation velocity of spinning and multi-headed detonations reasonably agrees with the ideal CJ values.

  17. The Fluidic Obstacle Technique: An Approach for Enhancing Deflagration-to-Detonation Transition in Pulsed Detonation Engines

    Science.gov (United States)

    Knox, Benjamin W.

    The current research explored the fluidic obstacle technique and obtained relative performance estimates of this new approach for enhancement of de agration-to-detonation transition. Optimization of conventional physical obstacles has comprised the majority of de agration-to-detonation enhancement research but these devices ultimately degrade the performance of a pulsed detonation engine. Therefore, a new approach has been investigated that demonstrates a fluidic obstacle has the potential to maximize turbulence production and enhance the flame acceleration process, leading to successful DDT. A fluidic obstacle is also able to reduce total pressure losses, "heat soaking", and ignition times. A reduction in these variables serves to maximize available thrust. In addition, the fluidic obstacle technique is an active combustion control method capable of adapting to off-design conditions. Steady non-reacting and unsteady reacting flow have been utilized in two facilities, namely the UB Combustion Laboratory and AFRL Detonation Engine Research facility, to provide experimental measurements and observations into the feasibility of this new approach.

  18. Benign schwannoma of the maxillary antrum.

    Science.gov (United States)

    Hegde, Oshin; Desai, Dinkar; Bhandarkar, Gowri P; Paul, Tony

    2016-01-01

    Schwannoma also known commonly as neurilemmoma and schwann cell tumor is a benign nerve sheath tumor. About 1/3(rd) cases of schwannoma arise from the head and neck region but rarely from the nasal and paranasal sinuses. The recurrence rate in these cases has reported to be very rare. We report a rare case of schwannoma in a 60-year-old woman arising from the maxillary sinus further eroding the orbital floor and nasal bone. We have also described the clinical presentation, radiological, histological findings, and management of the case. PMID:27095911

  19. Benign intracranial hypertension diagnosed with bilateral papilloedema

    Directory of Open Access Journals (Sweden)

    K. C. Phillips

    2013-12-01

    Full Text Available This article presents a case of benign intracranial hypertension (BIH diagnosed from the presence of papilloedema. This potentially sight-threatening condition particularly affects younger obese females and can be idiopathic, caused by adverse reaction to certain prescription medications or by systemic disease. Prompt treatment is essentialto avoid optic atrophy and low energy diet and exercise forms part of long-term treatment to avoid relapse. Optometrists can play a critical primary health care role in the detection of papilloedema and referring appropriately.

  20. Impact of radiation therapy for benign diseases

    International Nuclear Information System (INIS)

    Radiation therapy of benign diseases represent a wide panel of indications. Some indications are clearly identified as treatment of arteriovenous malformations (AVM), hyperthyroid ophthalmopathy, postoperative heterotopic bone formations or keloid scars. Some indications are under evaluation as complications induced by neo-vessels of age-related macular degeneration or coronary restenosis after angioplasty. Some indications remain controversial with poor evidence of efficiency as treatment of bursitis, tendinitis or Dupuytren's disease. Some indications are now obsolete such as warts, or contra-indicated as treatment of infant and children. (authors)

  1. OTC tamsulosin for benign prostatic hyperplasia.

    Science.gov (United States)

    2010-10-01

    Earlier this year, tamsulosin, an alpha blocker previously only available on prescription, became available for sale by pharmacists as a treatment for functional symptoms of benign prostatic hyperplasia (BPH) in men aged 45-75 years (Flomax Relief MR - Boehringer Ingelheim). A television advert for the over-the-counter (OTC) product claims that it is a "simple and effective" treatment that can relieve symptoms within 1 week, allowing the user to "take control of your annoying pee problems".¹ Here we review the evidence on tamsulosin and assess whether its availability as an OTC product confers worthwhile advantages. PMID:20926447

  2. A Study of Detonation Propagation and Diffraction with Compliant Confinement

    Energy Technology Data Exchange (ETDEWEB)

    Banks, J; Schwendeman, D; Kapila, A; Henshaw, W

    2007-08-13

    A previous computational study of diffracting detonations with the ignition-and-growth model demonstrated that contrary to experimental observations, the computed solution did not exhibit dead zones. For a rigidly confined explosive it was found that while diffraction past a sharp corner did lead to a temporary separation of the lead shock from the reaction zone, the detonation re-established itself in due course and no pockets of unreacted material were left behind. The present investigation continues to focus on the potential for detonation failure within the ignition-and-growth (IG) model, but now for a compliant confinement of the explosive. The aim of the present paper is two fold. First, in order to compute solutions of the governing equations for multi-material reactive flow, a numerical method of solution is developed and discussed. The method is a Godunov-type, fractional-step scheme which incorporates an energy correction to suppress numerical oscillations that would occur near the material interface separating the reactive material and the inert confiner for standard conservative schemes. The numerical method uses adaptive mesh refinement (AMR) on overlapping grids, and the accuracy of solutions is well tested using a two-dimensional rate-stick problem for both strong and weak inert confinements. The second aim of the paper is to extend the previous computational study of the IG model by considering two related problems. In the first problem, the corner-turning configuration is re-examined, and it is shown that in the matter of detonation failure, the absence of rigid confinement does not affect the outcome in a material way; sustained dead zones continue to elude the model. In the second problem, detonations propagating down a compliantly confined pencil-shaped configuration are computed for a variety of cone angles of the tapered section. It is found, in accord with experimental observation, that if the cone angle is small enough, the detonation fails

  3. Development of a Gas-Fed Pulse Detonation Research Engine

    Science.gov (United States)

    Litchford, Ron J.; Hutt, John (Technical Monitor)

    2001-01-01

    In response to the growing need for empirical data on pulse detonation engine performance and operation, NASA Marshall Space Flight Center has developed and placed into operation a low-cost gas-fed pulse detonation research engine. The guiding design strategy was to achieve a simple and flexible research apparatus, which was inexpensive to build and operate. As such, the engine was designed to operate as a heat sink device, and testing was limited to burst-mode operation with run durations of a few seconds. Wherever possible, maximum use was made of standard off-the-shelf industrial or automotive components. The 5-cm diameter primary tube is about 90-cm long and has been outfitted with a multitude of sensor and optical ports. The primary tube is fed by a coaxial injector through an initiator tube, which is inserted directly into the injector head face. Four auxiliary coaxial injectors are also integrated into the injector head assembly. All propellant flow is controlled with industrial solenoid valves. An automotive electronic ignition system was adapted for use, and spark plugs are mounted in both tubes so that a variety of ignition schemes can be examined. A microprocessor-based fiber-optic engine control system was developed to provide precise control over valve and ignition timing. Initial shakedown testing with hydrogen/oxygen mixtures verified the need for Schelkin spirals in both the initiator and primary tubes to ensure rapid development of the detonation wave. Measured pressure wave time-of-flight indicated detonation velocities of 2.4 km/sec and 2.2 km/sec in the initiator and primary tubes, respectively. These values implied a fuel-lean mixture corresponding to an H2 volume fraction near 0.5. The axial distribution for the detonation velocity was found to be essentially constant along the primary tube. Time-resolved thrust profiles were also acquired for both underfilled and overfilled tube conditions. These profiles are consistent with previous time

  4. Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

    Institute of Scientific and Technical Information of China (English)

    Xu-Dong Zhang; Bao-Chun Fan; Ming-Yue Gui; Zhen-Hua Pan; Gang Dong

    2012-01-01

    Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures.The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry.The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature.The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted.Owing to the unconfined character of detonation wavelet,a deficit of detonation parameters was observed.Due to the effects of wall geometries,the strength of the outside detonation front is stronger than that of the inside portion.The detonation thus propagates with a constant circular velocity.Numerical simulation also shows three-dimensional rotating detonation structures,which display specific feature of the detonationshock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity.It is believed that the present study could give an insight into the interesting properties of the continuously rotating detonation,and is thus beneficial to the design of continuous detonation propulsion systems.

  5. Histiocytic sarcoma that mimics benign histiocytosis.

    Science.gov (United States)

    Boisseau-Garsaud, A M; Vergier, B; Beylot-Barry, M; Nastasel-Menini, F; Dubus, P; de Mascarel, A; Eghbali, H; Beylot, C

    1996-06-01

    A 28-year-old man presented with a histiocytic sarcoma of a very uncommon origin, as it had developed for several years like a benign cutaneous histiocytosis resembling generalized eruptive histiocytoma before becoming acute, with nodal and massive pulmonary involvement. Despite various chemotherapies, the patient died within 8 months. Skin biopsies showed histiocytic proliferation in the dermis and node biopsies showed histiocytic proliferation with a sinusoidal pattern. Immunohistochemical analysis, performed on paraffin-embedded sections, demonstrated strong labeling of tumoral cells for CD68 and moderate labeling for CD3 and CD4. CD30 labeling was negative. S-100 protein was positive on a Langerhans' cell reactive subpopulation. Electron microscopy confirmed the histiocytic nature of malignant cells and showed cytoplasmic inclusions such as regularly laminated bodies, dense bodies and pleomorphic inclusions. No Birbeck granules were seen. A gene rearrangement study of T-cell receptor gamma and immunoglobulin heavy chain genes showed a germline configuration. Histiocytic sarcoma is an extremely rare true histiocytic malignancy, the existence of which has been recently debated since it has often been mistaken in the past for large cell lymphomas. Such a deceptive onset as benign cutaneous histiocytosis has not been described in the literature to our knowledge. PMID:8793665

  6. Directly thiolated modification onto the surface of detonation nanodiamonds.

    Science.gov (United States)

    Hsu, Ming-Hua; Chuang, Hong; Cheng, Fong-Yu; Huang, Ying-Pei; Han, Chien-Chung; Chen, Jiun-Yu; Huang, Su-Chin; Chen, Jen-Kun; Wu, Dian-Syue; Chu, Hsueh-Liang; Chang, Chia-Ching

    2014-05-28

    An efficient method for modifying the surface of detonation nanodiamonds (5 and 100 nm) with thiol groups (-SH) by using an organic chemistry strategy is presented herein. Thiolated nanodiamonds were characterized by spectroscopic techniques, and the atomic percentage of sulfur was analyzed by elemental analysis and X-ray photoelectron spectroscopy. The conjugation between thiolated nanodiamonds and gold nanoparticles was elucidated by transmission electron microscopy and UV-vis spectrometry. Moreover, the material did not show significant cytotoxicity to the human lung carcinoma cell line and may prospectively be applied in bioconjugated technology. The new method that we elucidated may significantly improve the approach to surface modification of detonation nanodiamonds and build up a new platform for the application of nanodiamonds. PMID:24766528

  7. Molecular dynamics simulations of detonation on the roadrunner supercomputer

    Science.gov (United States)

    Mniszewski, Susan; Cawkwell, Marc; Germann, Timothy C.

    2012-03-01

    The temporal and spatial scales intrinsic to a real detonating explosive are extremely difficult to capture using molecular dynamics (MD) simulations. Nevertheless, MD remains very attractive since it allows for the resolution of dynamic phenomena at the atomic scale. Large-scale reactive MD simulations in three dimensions require immense computational resources even when simple reactive force fields are employed. We focus on the REBO force field for 'AB' since it has been shown to support a detonation while being simple, analytic, and short-ranged. The transition from two-to three- dimensional simulations is being facilitated by the port of the REBO force field in the parallel MD code SPaSM to LANL's petaflop supercomputer 'Roadrunner'. We provide a detailed discussion of the challenges associated with computing interatomic forces on a hybrid Opteron/Cell BE computational architecture.

  8. Study of a model equation in detonation theory: multidimensional effects

    CERN Document Server

    Faria, Luiz M; Rosales, Rodolfo R

    2015-01-01

    We extend the reactive Burgers equation presented in Kasimov et al. Phys. Rev. Lett., 110 (2013) and Faria et al. SIAM J. Appl. Maths, 74 (2014), to include multidimensional effects. Furthermore, we explain how the model can be rationally justified following the ideas of the asymptotic theory developed in Faria et al. JFM (2015). The proposed model is a forced version of the unsteady small disturbance transonic flow equations. We show that for physically reasonable choices of forcing functions, traveling wave solutions akin to detonation waves exist. It is demonstrated that multidimensional effects play an important role in the stability and dynamics of the traveling waves. Numerical simulations indicate that solutions of the model tend to form multi-dimensional patterns analogous to cells in gaseous detonations.

  9. Performance Impact of Deflagration to Detonation Transition Enhancing Obstacles

    Science.gov (United States)

    Paxson, Daniel E.; Schauer, Frederick; Hopper, David

    2012-01-01

    A sub-model is developed to account for the drag and heat transfer enhancement resulting from deflagration-to-detonation (DDT) inducing obstacles commonly used in pulse detonation engines (PDE). The sub-model is incorporated as a source term in a time-accurate, quasi-onedimensional, CFD-based PDE simulation. The simulation and sub-model are then validated through comparison with a particular experiment in which limited DDT obstacle parameters were varied. The simulation is then used to examine the relative contributions from drag and heat transfer to the reduced thrust which is observed. It is found that heat transfer is far more significant than aerodynamic drag in this particular experiment.

  10. Ground-based Nuclear Detonation Detection (GNDD) Technology Roadmap

    International Nuclear Information System (INIS)

    This GNDD Technology Roadmap is intended to provide guidance to potential researchers and help management define research priorities to achieve technology advancements for ground-based nuclear explosion monitoring science being pursued by the Ground-based Nuclear Detonation Detection (GNDD) Team within the Office of Nuclear Detonation Detection in the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy (DOE). Four science-based elements were selected to encompass the entire scope of nuclear monitoring research and development (R&D) necessary to facilitate breakthrough scientific results, as well as deliver impactful products. Promising future R&D is delineated including dual use associated with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Important research themes as well as associated metrics are identified along with a progression of accomplishments, represented by a selected bibliography, that are precursors to major improvements to nuclear explosion monitoring.

  11. Study of a Model Equation in Detonation Theory

    KAUST Repository

    Faria, Luiz

    2014-04-24

    Here we analyze properties of an equation that we previously proposed to model the dynamics of unstable detonation waves [A. R. Kasimov, L. M. Faria, and R. R. Rosales, Model for shock wave chaos, Phys. Rev. Lett., 110 (2013), 104104]. The equation is ut+ 1/2 (u2-uu (0-, t))x=f (x, u (0-, t)), x > 0, t < 0. It describes a detonation shock at x = 0 with the reaction zone in x > 0. We investigate the nature of the steady-state solutions of this nonlocal hyperbolic balance law, the linear stability of these solutions, and the nonlinear dynamics. We establish the existence of instability followed by a cascade of period-doubling bifurcations leading to chaos. © 2014 Society for Industrial and Applied Mathematics.

  12. Geometry effects on detonation in vapor-deposited hexanitroazobenzene (HNAB)

    Science.gov (United States)

    Tappan, Alexander S.; Wixom, Ryan R.; Knepper, Robert

    2015-06-01

    Physical vapor deposition is a technique that can be used to produce explosive films with controlled geometry and microstructure. Films of the high explosive hexanitroazobenzene (HNAB) were deposited by vacuum thermal evaporation. HNAB deposits in an amorphous state that crystallizes over time into a polycrystalline material with high density and a consistent porosity distribution. In previous work, we have evaluated detonation critical thickness in HNAB films in an effectively infinite slab geometry with insignificant side losses. In this work, the effect of geometry on detonation failure was investigated by performing experiments on films with different thicknesses, while also changing dimensions such that side losses became significant. Films were characterized with surface profilometry and scanning electron microscopy. The results of these experiments will be discussed in the context of small sample geometry, deposited film microstructure, and density.

  13. Engineering models of deflagration-to-detonation transition

    Energy Technology Data Exchange (ETDEWEB)

    Bdzil, J.B.; Son, S.F.

    1995-07-01

    For the past two years, Los Alamos has supported research into the deflagration-to-detonation transition (DDT) in damaged energetic materials as part of the explosives safety program. This program supported both a theory/modeling group and an experimentation group. The goal of the theory/modeling group was to examine the various modeling structures (one-phase models, two-phase models, etc.) and select from these a structure suitable to model accidental initiation of detonation in damaged explosives. The experimental data on low-velocity piston supported DDT in granular explosive was to serve as a test bed to help in the selection process. Three theoretical models have been examined in the course of this study: (1) the Baer-Nunziato (BN) model, (2) the Stewart-Prasad-Asay (SPA) model and (3) the Bdzil-Kapila-Stewart model. Here we describe these models, discuss their properties, and compare their features.

  14. Application of fast infrared detectors to detonation science

    International Nuclear Information System (INIS)

    Infrared radiometers have been used to make time-resolved emission measurements of shocked explosives. Instruments of moderate time resolution were used to estimate temperatures in shocked but not detonated explosives. The heterogeneity of the shock-induced heating was discovered in pressed explosives by two-band techniques, and the time-resolved emittance or extent of hot spot coverage indicated a great dependence on shock pressures. Temperatures in moderately shocked organic liquids were also measured. Faster response radiometers with 5 ns rise times based on InSb and HgCdTe photovoltaic detectors were constructed and tested. Preliminary data on reactive shocks and detonations reveal a resolution of the heating in the shock wave and the following reaction

  15. Thrust Measurements for a Pulse Detonation Engine Driven Ejector

    Science.gov (United States)

    Santoro, Robert J.; Pak, Sibtosh; Shehadeh, R.; Saretto, S. R.; Lee, S.-Y.

    2005-01-01

    Results of an experimental effort on pulse detonation driven ejectors aimed at probing different aspects of PDE ejector processes, are presented and discussed. The PDE was operated using ethylene as the fuel and an equimolar oxygen/nitrogen mixture as the oxidizer at an equivalence ratio of one. The thrust measurements for the PDE alone are in excellent agreement with experimental and modeling results reported in the literature and serve as a Baseline for the ejector studies. These thrust measurements were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups using constant diameter ejector tubes and various detonation tube/ejector tube overlap distances. The results show that for the geometries studied here, a maximum thrust augmentation of 24% is achieved. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

  16. Mechanical effects of gaseous detonations on a flexible confinement

    International Nuclear Information System (INIS)

    A mathematical model was developed for evaluating the effect of a detonating gaseous mixture on its elastic circular confinement. The data provided by the model were compared with experimental results. The confinement materials investigated include polyvinylchloride and stainless steel. Measurements of transverse and longitudinal deformations of the confinement material at several detonation velocities and for different material properties made it possible to determine the deformation characteristics, taking into account the precursor effect, the oscillations and their frequencies, the deformation ratio, and the dynamic amplifying factors. A certain lack of agreement between the theoretical data obtained with the aid of the model and the experimental results is probably related to simplified assumptions made in the model regarding the pressure distributions and a failure to take into account viscosity effects

  17. Ground-based Nuclear Detonation Detection (GNDD) Technology Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Leslie A.

    2014-01-13

    This GNDD Technology Roadmap is intended to provide guidance to potential researchers and help management define research priorities to achieve technology advancements for ground-based nuclear explosion monitoring science being pursued by the Ground-based Nuclear Detonation Detection (GNDD) Team within the Office of Nuclear Detonation Detection in the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy (DOE). Four science-based elements were selected to encompass the entire scope of nuclear monitoring research and development (R&D) necessary to facilitate breakthrough scientific results, as well as deliver impactful products. Promising future R&D is delineated including dual use associated with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Important research themes as well as associated metrics are identified along with a progression of accomplishments, represented by a selected bibliography, that are precursors to major improvements to nuclear explosion monitoring.

  18. Far Field Modeling Methods For Characterizing Surface Detonations

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    Savannah River National Laboratory (SRNL) analyzed particle samples collected during experiments that were designed to replicate tests of nuclear weapons components that involve detonation of high explosives (HE). SRNL collected the particle samples in the HE debris cloud using innovative rocket propelled samplers. SRNL used scanning electronic microscopy to determine the elemental constituents of the particles and their size distributions. Depleted uranium composed about 7% of the particle contents. SRNL used the particle size distributions and elemental composition to perform transport calculations that indicate in many terrains and atmospheric conditions the uranium bearing particles will be transported long distances downwind. This research established that HE tests specific to nuclear proliferation should be detectable at long downwind distances by sampling airborne particles created by the test detonations.

  19. Circumstellar absorption in double detonation Type Ia supernovae

    CERN Document Server

    Shen, Ken J; Foley, Ryan J

    2013-01-01

    Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He-C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O white dwarf prior to the He core's tidal disruption. We find that this material is ejected from the binary system and sweeps up the surrounding interstellar medium hundreds to thousands of years before the SN Ia. The close match between the resulting circumstellar medium profiles and values inferred from recent observations of circumstellar absorption in SNe Ia gives further credence to the resurgent double detonation scenario.

  20. CIRCUMSTELLAR ABSORPTION IN DOUBLE DETONATION TYPE Ia SUPERNOVAE

    International Nuclear Information System (INIS)

    Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He+C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O white dwarf prior to the He core's tidal disruption. We find that this material is ejected from the binary system and sweeps up the surrounding interstellar medium hundreds to thousands of years before the SN Ia. The close match between the resulting circumstellar medium profiles and values inferred from recent observations of circumstellar absorption in SNe Ia gives further credence to the resurgent double detonation scenario.

  1. Parameters of the equilibrium gas flow in a detonation equipment

    International Nuclear Information System (INIS)

    Equipment for the detonation method of depositing coatings was designed without a detailed understanding of the process dynamics. A simplified assumption was made about the detonation products DP: that is, that it was an inert gas with a constant adiabatic parameter. Molecular dissociation was neglected, resulting in a substantial overestimate of the metal particle temperature. In this paper DP is considered as a reacting medium with an equilibrium composition. The parameters of the gas flow for a DW propagating in a tube are derived (such as the mass velocity distribution of DP behind a DW front). Experiments agree with calculations. Finally, an algorithm is devised to allow one to solve the problem of the neglected dissociation

  2. Detonation initiation developing from the Richtmyer-Meshkov instability

    Institute of Scientific and Technical Information of China (English)

    H.H.Teng; Z.L.Jiang; Z.M.Hu

    2007-01-01

    Detonation initiation resulting from theRichtmyer-Meshkov instability is investigated numericallyin the configuration of the shock/spark-induced-deflagrationinteraction in a combustive gas mixture. Two-dimensionalmulti-species Navier-Stokes equations implemented with thedetailed chemical reaction model are solved with thedispersion-controlled dissipative scheme. Numerical resultsshow that the spark can create a blast wave and ignite defla-grations. Then, the deflagration waves are enhanced due tothe Richtmyer-Meshkov instability, which provides detona-tion initiations with local environment conditions. Byexamining the deflagration fronts, two kinds of the initiationmechanisms are identified. One is referred to as the deflagra-tion front acceleration with the help of the weak shock wave,occurring on the convex surfaces, and the other is the hotspot explosion deriving from the deflagration front focusing,occurring on the concave surfaces.

  3. Effect of turbulence on deflagration to detonation transition

    International Nuclear Information System (INIS)

    The interaction of a turbulent jet and an expanding flame kernel was examined using spark-schlieren photography and piezoelectric pressure transducers. Experiments were performed in a 9 by 9 cm, 4-m-long shock channel. Results show that an expanding flame kernel can be locally, or partially, quenched by flame stretching. The mixing of the hot combustion products, containing reactive species, with the unburnt gas in the turbulent flame-jet, created pockets of sensitized mixture. The subsequent re-ignition of the sensitized mixture could result in a local explosion. In a number of experiments the blast waves produced in the local explosion developed into detonation waves. A local explosion occurred only if there was partial quenching of the flame kernel. Partial quenching occurs when the Karlovitz-Kovaszney factor approaches unity and, therefore, it is possible to establish a set of conditions in terms of turbulent parameters for the transition to detonation. (author). 16 refs., 13 figs

  4. Set-valued solutions for non-ideal detonation

    Science.gov (United States)

    Semenko, R.; Faria, L. M.; Kasimov, A. R.; Ermolaev, B. S.

    2016-03-01

    The existence and structure of a steady-state gaseous detonation propagating in a packed bed of solid inert particles are analyzed in the one-dimensional approximation by taking into consideration frictional and heat losses between the gas and the particles. A new formulation of the governing equations is introduced that eliminates the difficulties with numerical integration across the sonic singularity in the reactive Euler equations. With the new algorithm, we find that when the sonic point disappears from the flow, there exists a one-parameter family of solutions parameterized by either pressure or temperature at the end of the reaction zone. These solutions (termed "set-valued" here) correspond to a continuous spectrum of the eigenvalue problem that determines the detonation velocity as a function of a loss factor.

  5. Evaluation of the effects of detonation in a spherical bomb

    International Nuclear Information System (INIS)

    An analysis is presented of the time-dependent pressure forces and impulse loadings on the walls of the hemispherical dome of a nuclear reactor pressure vessel arising from a centrally ignited hydrogen-oxygen detonation. Investigated in this context are the effects of richness of the detonable gas mixture as well as those due to the inclusion of water vapor. In the analysis the gas mixture was treated as a perfect gas, and the partial differential equations governing the gasdynamic flow were integrated using the CLOUD CODE - a finite-difference technique set in Lagrangian coordinates and incorporating the smoothing action of artificial viscosity. The most interesting results pertain to the ringing of pressure pulses at the walls. Their frequency is quite uniform, and their pressure peaks, at levels significantly higher than that of combustion at constant volume, decay at a negligible rate

  6. Detonating Failed Deflagration Model of Thermonuclear Supernovae I. Explosion Dynamics

    CERN Document Server

    Plewa, T

    2006-01-01

    We present a detonating failed deflagration model of Type Ia supernovae. In this model, the thermonuclear explosion of a massive white dwarf follows an off-center deflagration. We conduct a survey of asymmetric ignition configurations initiated at various distances from the stellar center. In all cases studied, we find that only a small amount of stellar fuel is consumed during deflagration phase, no explosion is obtained, and the released energy is mostly wasted on expanding the progenitor. Products of the failed deflagration quickly reach the stellar surface, polluting and strongly disturbing it. These disturbances eventually evolve into small and isolated shock-dominated regions which are rich in fuel. We consider these regions as seeds capable of forming self-sustained detonations that, ultimately, result in the thermonuclear supernova explosion. Preliminary nucleosynthesis results indicate the model supernova ejecta are typically composed of about 0.1-0.25 Msun of silicon group elements, 0.9-1.2 Msun of ...

  7. Intraosseous Benign Lesions of the Jaws: A Radiographic Study

    OpenAIRE

    Javadian Langaroodi, Adineh; Lari, Sima Sadat; Shokri, Abbas; Hoseini Zarch, Seyed Hossein; Jamshidi, Shokofeh; Akbari, Peyman

    2014-01-01

    Background: Benign maxillo-mandibular tumors and cysts, which are relatively common findings on radiographs, namely the ubiquitous panoramic view, have to be dealt with by dentists on a daily basis. Objectives: The aim of this study is to evaluate the panoramic radiographic findings pertaining to benign and tumoral lesions in the maxilla and mandible. Patients and Methods: Applying a case series method, panoramic images of 61 patients with cysts, benign tumors and tumor-like lesions in the ja...

  8. Benign Paroxysmal Positional Vertigo After Nonotologic Surgery: Case Series

    OpenAIRE

    Kansu, Leyla; Aydin, Erdinc; Gulsahi, Kamran

    2012-01-01

    Benign paroxysmal positional vertigo is one of the most common types of vertigo caused by peripheral vestibular dysfunction. Although head trauma, migraine, long-term bed rest, Ménière disease, viral labyrinthitis, and upper respiratory tract infections are believed to be predisposing factors, most cases of benign paroxysmal positional vertigo are idiopathic. Ear surgery is another cause, but after non-otologic surgery, attacks of benign paroxysmal positional vertigo are rare. We describe thr...

  9. Multi-frame visualization for detonation wave diffraction

    Science.gov (United States)

    Nagura, Y.; Kasahara, J.; Matsuo, A.

    2016-05-01

    When a detonation wave emerges from a tube into unconfined space filled with a gas mixture, detonation wave diffraction occurs due to abrupt changes in the cross-sectional area. In the present study, we focused on the local explosion in reinitiation and propagation of a transverse detonation wave by performing comprehensive and direct observation with high time resolution visualization in a two-dimensional rectangular channel. Using the visualization methods of shadowgraph and multi-frame, short-time, open-shutter photography, we determined where the wall reflection point is generated, and also determined where the bright point is originated by the local explosion, and investigated the effects of the deviation angle and initial pressure of the gas mixture. We found that the reinitiation of detonation had two modes that were determined by the deviation angle of the channel. If the deviation angle was less than or equal to 30°, the local explosion of reinitiation might occur in the vicinity of the channel wall, and if the deviation angle was greater than or equal to 60°, the local explosion might originate on the upper side of the tube exit. With a deviation angle greater than 60°, the position of the wall reflection point depended on the cell width, so the radial distance of the wall reflection point from the apex of the tube exit was about 12 times the cell width. Similarly, the bright point (local explosion point) was located a distance of about 11 times the cell width from the apex of the tube exit, with a circumferential angle of 48°.

  10. Lead Shock Oscillation and Decoupling in Propagating Detonations

    OpenAIRE

    Austin, J. M.; Pintgen, F.; Shepherd, J. E.

    2005-01-01

    Experimental images of propagating detonation waves provide lead shock velocity measurements through the cell cycle. We examine the issue of local decoupling of the shock and reaction front using these data. In highly unstable mixtures with high reduced activation energy, experimental images and analysis suggest that local decoupling occurs at the end of the cell cycle. Regions of high fluorescence intensity are observed in shear layers in apparently decoupled portions...

  11. Pulse Detonation Rocket Engine Research at NASA Marshall

    Science.gov (United States)

    Morris, Christopher I.

    2003-01-01

    Pulse detonation rocket engines (PDREs) offer potential performance improvements over conventional designs, but represent a challenging modeling task. A quasi 1-D, finite-rate chemistry CFD model for a PDRE is described and implemented. A parametric study of the effect of blowdown pressure ratio on the performance of an optimized, fixed PDRE nozzle configuration is reported. The results are compared to a steady-state rocket system using similar modeling assumptions.

  12. Radiation preheating can trigger transition from deflagration to detonation

    OpenAIRE

    Karlin, Vladimir

    2010-01-01

    In this article effect of radiation preheating of unburnt mixture by propagating deflagration front is studied from the viewpoint of its ability to form a promoting temperature gradient and trigger transition to detonation. First, we investigate the effect of radiation preheating of the unburnt mixtures, when they are traveling through the wrinkles on the flame surface, in order to estimate a possibility of significant temperature rise. Subsequently, numerical simulations of a simplified math...

  13. Fuel injection strategy for a next generation pulse detonation engine

    OpenAIRE

    Robbins, Tad J.

    2006-01-01

    The Pulse Detonation Engine offers the Department of Defense a new low cost, light weight, and efficient solution to supersonic flight on many of its small airborne platforms. In the past, both liquid fuel and gaseous fuel designs have been partially developed and tested. Several aspects of these configurations have led to the need for the development of a new design, in particular the reduction of total pressure losses, and the removal of auxiliary oxygen system previously required to ini...

  14. Shock-to-detonation transition in solid heterogeneous explosives

    International Nuclear Information System (INIS)

    This paper is an overview of the studies performed during the last decades on the shock-to-detonation transition process in heterogeneous explosives. We present the experimental and theoretical approaches mentioned in the literature and/or developed at CEA/DAM. The aim is to identify which main mechanisms govern this transition process and to evaluate the relevance of the available modeling tools. (author)

  15. Design of a coaxial split flow pulse detonation engine

    OpenAIRE

    Hall, Philip D.

    2006-01-01

    Future Navy Capabilities indicate the need for a supersonic cruise missile. Thus the need exists for a low cost, light-weight, and efficient means of supersonic propulsion. NPS has been developing the Pulse Detonation Engine, which in theory has a thermodynamic efficiency greater than 50% as compared to 35% for state of the art constant-pressure cycles currently in use in gas turbines/ramjets/scramjets. Nonetheless, there are two major problems in the development of this engine. These are t...

  16. Studies of alumina coatings formation by detonation-gun spraying

    International Nuclear Information System (INIS)

    In this paper the mechanism of detonation sprayed alumina coatings formation has been described. The detonation gun DNP5M was used spray AI/sub 2/O/sub 3/ powders having rticle diameters were between 10 and 14 micro meter. The D-Gun has L A 79 a 0.8 m-length barrel with convergent variable cross-section by volume of 0.0006 m3. The rate of fire 2.1 cycle. Per second during samples spraying was used. There is strong dependence of characteristics of obtained coatings from powder cloud location in the barrel composition of gas mixture, and barrel filling factor by gas mixture. The monotone decreasing of hardness am cross-section area of solitary coatings layers was detected. The retention of fair quantity of alpha AI/sub 2/O/sub 3/ into gas detonation sprayed coatings is connected with reduced cooling rate of solitary coatings layers, as well as with possibility of coating formation from partially melted particles at high velocity collision with substrate surface. Usually for obtaining high content of corundum AI/sub 2/O/sub 3/ into gas detonation sprayed coatings, the thickness of solitary coatings layers is increasing up to 8-18 micro meter. However, the content of alpha- AI/sub 2/O/sub 3/ into coatings depends also on other factors; increase of frequency of powder particles -substrate surface collisions during formation of solitary coatings layers; additional generation of heat due to conversion of kinetic energy to thermal; essential increase of contact temperature as result of crystallization temperature increase during impact with velocity close to 500 m/sec; and corresponding decrease of time for processing of transfer gamma-AI/sub 2/O/sub 3/ alpha-AI/sub 2/O/sub 3/ with temperature increase. (author)

  17. Set-valued solutions for non-ideal detonation

    OpenAIRE

    Semenko, Roman; Faria, Luiz; Kasimov, Aslan; Ermolaev, Boris

    2013-01-01

    The existence and structure of steady gaseous detonation propagating in a packed bed of solid inert particles are analyzed in the one-dimensional approximation by taking into consideration frictional and heat losses between the gas and the particles. A new formulation of the governing equations is introduced that eliminates the well-known difficulties with numerical integration across the sonic singularity in the reactive Euler equations. The new algorithm allows us to determine that the deto...

  18. Long-term worldwide effects of multiple nuclear weapons detonations

    International Nuclear Information System (INIS)

    The NAS report, issued in 1975 shocked the scientific community by suggesting that detonation of a fraction of the world's nuclear arsenal (104 megatons) could produce a major, 30-70%, reduction in stratospheric ozone, lasting a year or more. The consequences of such a reduction in the natural barrier to solar ultraviolet radiation include the potential extinction of mammalian life. The summary section of the 1975 report is reprinted here

  19. Triple point shear-layers in gaseous detonation waves

    OpenAIRE

    Massa, L.; Austin, J. M.; Jackson, T. L.

    2006-01-01

    Recent experiments have shown intriguing regions of intense luminescence or ‘hotspots’ in the vicinity of triple-point shear layers in propagating gaseous detonation waves. Localized explosions have also been observed to develop in these fronts. These features were observed in higher effective activation energy mixtures, but not in lower effective activation energy mixtures. The increased lead shock oscillation through a cell cycle in higher activation energy mixtures may result in a signific...

  20. Benign and malignant tumors of the foot and ankle

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Adam D.; Datir, Abhijit; Langley, Travis [Emory University Hospital, Department of Radiology, Section of Musculoskeletal Imaging, Atlanta, GA (United States); Tresley, Jonathan [University of Wisconsin, Department of Radiology, Madison, WI (United States); Clifford, Paul D.; Jose, Jean; Subhawong, Ty K. [University of Miami, Department of Radiology, Miami, FL (United States)

    2016-03-15

    Pain and focal masses in the foot and ankle are frequently encountered and often initiate a workup including imaging. It is important to differentiate benign lesions from aggressive benign or malignant lesions. In this review, multiple examples of osseous and soft tissue tumors of the foot and ankle will be presented. Additionally, the compartmental anatomy of the foot and ankle will be discussed in terms of its relevance for percutaneous biopsy planning and eventual surgery. Finally, a general overview of the surgical management of benign, benign aggressive and malignant tumors of the foot and ankle will be discussed. (orig.)

  1. Benign and malignant tumors of the foot and ankle

    International Nuclear Information System (INIS)

    Pain and focal masses in the foot and ankle are frequently encountered and often initiate a workup including imaging. It is important to differentiate benign lesions from aggressive benign or malignant lesions. In this review, multiple examples of osseous and soft tissue tumors of the foot and ankle will be presented. Additionally, the compartmental anatomy of the foot and ankle will be discussed in terms of its relevance for percutaneous biopsy planning and eventual surgery. Finally, a general overview of the surgical management of benign, benign aggressive and malignant tumors of the foot and ankle will be discussed. (orig.)

  2. Linear and nonlinear effects in detonation wave structure formation

    Science.gov (United States)

    Borisov, S. P.; Kudryavtsev, A. N.

    2016-06-01

    The role of linear and nonlinear effects in the process of formation of detonation wave structure is investigated using linear stability analysis and direct numerical simulation. A simple model with a one-step irreversible chemical reaction is considered. For linear stability computations, both the local iterative shooting procedure and the global Chebyshev pseudospectral method are employed. Numerical simulations of 1D pulsating instability are performed using a shock fitting approach based on a 5th order upwind-biased compact-difference discretization and a shock acceleration equation deduced from the Rankine-Hugoniot conditions. A shock capturing WENO scheme of the 5th order is used to simulate propagation of detonation wave in a plane channel. It is shown that the linear analysis predicts correctly the mode dominating on early stages of flow evolution and the size of detonation cells which emerge during these stages. Later, however, when a developed self-reproducing cellular structure forms, the cell size is approximately doubled due to nonlinear effects.

  3. Energy Loss in Pulse Detonation Engine due to Fuel Viscosity

    Directory of Open Access Journals (Sweden)

    Weipeng Hu

    2014-01-01

    Full Text Available Fluid viscosity is a significant factor resulting in the energy loss in most fluid dynamical systems. To analyze the energy loss in the pulse detonation engine (PDE due to the viscosity of the fuel, the energy loss in the Burgers model excited by periodic impulses is investigated based on the generalized multisymplectic method in this paper. Firstly, the single detonation energy is simplified as an impulse; thus the complex detonation process is simplified. And then, the symmetry of the Burgers model excited by periodic impulses is studied in the generalized multisymplectic framework and the energy loss expression is obtained. Finally, the energy loss in the Burgers model is investigated numerically. The results in this paper can be used to explain the difference between the theoretical performance and the experimental performance of the PDE partly. In addition, the analytical approach of this paper can be extended to the analysis of the energy loss in other fluid dynamic systems due to the fluid viscosity.

  4. Shock and Detonation Physics at Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Robbins, David L [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Steve A [Los Alamos National Laboratory

    2012-08-22

    WX-9 serves the Laboratory and the Nation by delivering quality technical results, serving customers that include the Nuclear Weapons Program (DOE/NNSA), the Department of Defense, the Department of Homeland Security and other government agencies. The scientific expertise of the group encompasses equations-of-state, shock compression science, phase transformations, detonation physics including explosives initiation, detonation propagation, and reaction rates, spectroscopic methods and velocimetry, and detonation and equation-of-state theory. We are also internationally-recognized in ultra-fast laser shock methods and associated diagnostics, and are active in the area of ultra-sensitive explosives detection. The facility capital enabling the group to fulfill its missions include a number of laser systems, both for laser-driven shocks, and spectroscopic analysis, high pressure gas-driven guns and powder guns for high velocity plate impact experiments, explosively-driven techniques, static high pressure devices including diamond anvil cells and dilatometers coupled with spectroscopic probes, and machine shops and target fabrication facilities.

  5. Modification of the colony tower for the Rio Blanco detonation

    International Nuclear Information System (INIS)

    Supplemental structural bracing was designed and installed for the 180-ft-tall Colony Tower, an experimental oil shale processing retort structure, in anticipation of its lateral response to the Rio Blanco detonation. The tower is a steel structure with both horizontal and vertical diagonal bracing. Data obtained from the earlier Project Rulison detonation indicated that an evaluation study was necessary. Design criteria that would provide an adequate margin of safety were developed based on predicted Rio Blanco ground motion. The evaluation of the unmodified structure showed that several bracing members would be subjected to forces exceeding their yield strength, and some would reach a level at which failure could occur. Further analyses were made with assumed modified bracing members. A final scheme for modified vertical bracing was established and installed. After modification, the response of the tower during the Rio Blanco detonation was measured by instruments on the ground and at various locations on the tower, and no evidence of damage was discovered. The modification of the Colony Tower and the procedures used to determine these modifications show the usefulness of current ground motion and structural response prediction technology for forecasting dynamic behavior of important structures subjected to ground motion from underground nuclear explosions. (auth)

  6. Equations of state of detonation products: ammonia and methane

    Science.gov (United States)

    Lang, John; Dattelbaum, Dana; Goodwin, Peter; Garcia, Daniel; Coe, Joshua; Leiding, Jeffery; Gibson, Lloyd; Bartram, Brian

    2015-06-01

    Ammonia (NH3) and methane (CH4) are two principal product gases resulting from explosives detonation, and the decomposition of other organic materials under shockwave loading (such as foams). Accurate thermodynamic descriptions of these gases are important for understanding the detonation performance of high explosives. However, shock compression data often do not exist for molecular species in the dense gas phase, and are limited in the fluid phase. Here, we present equation of state measurements of elevated initial density ammonia and methane gases dynamically compressed in gas-gun driven plate impact experiments. Pressure and density of the shocked gases on the principal Hugoniot were determined from direct particle velocity and shock wave velocity measurements recorded using optical velocimetry (Photonic Doppler velocimetry (PDV) and VISAR (velocity interferometer system for any reflector)). Streak spectroscopy and 5-color pyrometry were further used to measure the emission from the shocked gases, from which the temperatures of the shocked gases were estimated. Up to 0.07 GPa, ammonia was not observed to ionize, with temperature remaining below 7000 K. These results provide quantitative measurements of the Hugoniot locus for improving equations of state models of detonation products.

  7. On detonation initiation by a temperature gradient for a detailed chemical reaction models

    International Nuclear Information System (INIS)

    The evolution from a temperature gradient to a detonation is investigated for combustion mixture whose chemistry is governed by a detailed chemical kinetics. We show that a detailed chemical reaction model has a profound effect on the spontaneous wave concept for detonation initiation by a gradient of reactivity. The evolution to detonation due to a temperature gradient is considered for hydrogen-oxygen and hydrogen-air mixtures at different initial pressures. It is shown that the minimal length of the temperature gradient for which a detonation can be ignited is much larger than that predicted from a one-step chemical model. - Highlights: → We study detonation initiation by temperature gradient for detailed chemical models. → Detailed chemical models have a profound effect on the spontaneous wave concept. → Initiating detonation by temperature gradient differs from one-step model. → In real fuels DDT can not be initiated by temperature gradient.

  8. Multi-Dimensional Double Detonation of Sub-Chandrasekhar Mass White Dwarfs

    CERN Document Server

    Moll, Rainer

    2013-01-01

    Using 2D and 3D simulation, we study the "robustness" of the double detonation scenario for Type Ia supernovae, in which a detonation in the helium shell of a carbon-oxygen white dwarf induces a secondary detonation in the underlying core. We find that a helium detonation cannot easily descend into the core unless it commences (artificially) well above the hottest layer calculated for the helium shell in current presupernova models. Compressional waves induced by the sliding helium detonation, however, robustly generate hot spots which trigger a detonation in the core. Our simulations show that this is true even for non-axisymmetric initial conditions. If the helium is ignited at multiple points, the internal waves can pass through one another or be reflected, but this added complexity does not defeat the generation of the hot spot. The ignition of very low-mass helium shells depends on whether a thermonuclear runaway can simultaneously commence in a sufficiently large region.

  9. Munitions having an insensitive detonator system for initiating large failure diameter explosives

    Science.gov (United States)

    Perry, III, William Leroy

    2015-08-04

    A munition according to a preferred embodiment can include a detonator system having a detonator that is selectively coupled to a microwave source that functions to selectively prime, activate, initiate, and/or sensitize an insensitive explosive material for detonation. The preferred detonator can include an explosive cavity having a barrier within which an insensitive explosive material is disposed and a waveguide coupled to the explosive cavity. The preferred system can further include a microwave source coupled to the waveguide such that microwaves enter the explosive cavity and impinge on the insensitive explosive material to sensitize the explosive material for detonation. In use the preferred embodiments permit the deployment and use of munitions that are maintained in an insensitive state until the actual time of use, thereby substantially preventing unauthorized or unintended detonation thereof.

  10. Analysis of particle dynamics and heat transfer in detonation thermal spraying systems

    Science.gov (United States)

    Ramadan, K.; Butler, P. Barry

    2004-06-01

    A computational study of pulsed detonation thermal spraying is conducted using an axisymmetric two-dimensional transient gaseous detonation model. The variations of the particle velocity and temperature at impact on the target surface with the particle initial loading location are analyzed for different conditions. The geometry of the system and the loading locations of the particulate phase are key parameters in pulsed detonation thermal spraying. Since the process is extremely transient and the gas phase experiences a wide range of transient stages all on a timescale of a millisecond, the particle characteristics are strongly dependent on the instantaneous location in the gas stream. One cycle of detonation thermal spraying occurs on a time scale on the order of a millisecond due to the high gas velocities associated with detonation. Thus, a precise control of the process variable parameters is required to have a successful detonation coating process.

  11. Management of benign prostatic hyperplasia with silodosin

    Directory of Open Access Journals (Sweden)

    Tomonori Yamanishi

    2009-08-01

    Full Text Available Tomonori Yamanishi1, Tomoya Mizuno1, Takao Kamai1, Ken-ichiro Yoshida1, Ryuji Sakakibara2, Tomoyuki Uchiyama31Department of Urology, Dokkyo Medical University, Tochigi, Japan; 2Department of Neurology, Sakura Hospital, Toho University, Toho, Japan; 3Department of Neurology, Chiba University, Chiba, JapanAbstract: It has been reported that blockade of α1A-adrenoceptor (AR relieves bladder outlet obstruction, while blockade of α1D-AR is believed to alleviate storage symptoms due to detrusor overactivity. Silodosin, (--1-(3-hydroxypropyl-5-[(2R-2-({2-[2-(2,2,2trifluoroethoxy phenoxy]ethyl}aminopropyl]-2,3-dihydro-1H-indole-7- carboxamide, is a new α1A-AR selective antagonist. Silodosin is highly selective for the α1A-AR subtype, showing an affinity for the α1A-AR that is 583- and 55.5-fold higher than its affinity for the α1B- and α1D-ARs, respectively. In randomized, double-blind, placebo-controlled phase III studies performed in Japan and the United States, silodosin has been shown to be effective for both storage and voiding symptoms associated with benign prostatic hyperplasia. Early effects of silodosin (after 2–6 hours or day 1 on lower urinary tract symptoms have also been reported. In urodynamic studies, detrusor overactivity disappeared in 40% and improved in 35% of patients after administration. In pressure flow studies, the grade of obstruction on the International Continence Society nomogram showed improvement in 56% of patients. The rate of adverse events in the silodosin, tamsulosin and placebo groups was 88.6%, 82.3%, and 71.6%, respectively. The most common adverse event was (mostly mild abnormal ejaculation (28.1%. However, few patients (2.8% discontinued silodosin because of abnormal ejaculation. Orthostatic hypotension showed a similar incidence in the silodosin (2.6% and placebo (1.5% groups. In conclusion, silodosin improves detrusor overactivity and obstruction and thus may be effective for both storage and voiding

  12. On the propagation mechanism of a detonation wave in a round tube with orifice plates

    Science.gov (United States)

    Ciccarelli, G.; Cross, M.

    2016-06-01

    This study deals with the investigation of the detonation propagation mechanism in a circular tube with orifice plates. Experiments were performed with hydrogen air in a 10-cm-inner-diameter tube with the second half of the tube filled with equally spaced orifice plates. A self-sustained Chapman-Jouguet (CJ) detonation wave was initiated in the smooth first half of the tube and transmitted into the orifice-plate-laden second half of the tube. The details of the propagation were obtained using the soot-foil technique. Two types of foils were used between obstacles, a wall-foil placed on the tube wall, and a flat-foil (sooted on both sides) placed horizontally across the diameter of the tube. When placed after the first orifice plate, the flat foil shows symmetric detonation wave diffraction and failure, while the wall foil shows re-initiation via multiple local hot spots created when the decoupled shock wave interacts with the tube wall. At the end of the tube, where the detonation propagated at an average velocity much lower than the theoretical CJ value, the detonation propagation is much more asymmetric with only a few hot spots on the tube wall leading to local detonation initiation. Consecutive foils also show that the detonation structure changes after each obstacle interaction. For a mixture near the detonation propagation limit, detonation re-initiation occurs at a single wall hot spot producing a patch of small detonation cells. The local overdriven detonation wave is short lived, but is sufficient to keep the global explosion front propagating. Results associated with the effect of orifice plate blockage and spacing on the detonation propagation mechanism are also presented.

  13. The Effects of Curvature and Expansion on Helium Detonations on White Dwarf Surfaces

    OpenAIRE

    Moore, Kevin; Townsley, Dean; Bildsten, Lars

    2013-01-01

    Accreted helium layers on white dwarfs have been highlighted for many decades as a possible site for a detonation triggered by a thermonuclear runaway. In this paper, we find the minimum helium layer thickness that will sustain a steady laterally propagating detonation and show that it depends on the density and composition of the helium layer, specifically C12 and O16. Detonations in these thin helium layers have speeds slower than the Chapman-Jouget (CJ) speed from complete helium burning, ...

  14. Radiation Injury After a Nuclear Detonation: Medical Consequences and the Need for Scarce Resources Allocation

    OpenAIRE

    DiCarlo, Andrea L.; Maher, Carmen; Hick, John L.; Hanfling, Dan; Dainiak, Nicholas; Chao, Nelson; Bader, Judith L; Coleman, C. Norman; Weinstock, David M.

    2011-01-01

    A 10-kiloton (kT) nuclear detonation within a US city could expose hundreds of thousands of people to radiation. The Scarce Resources for a Nuclear Detonation Project was undertaken to guide community planning and response in the aftermath of a nuclear detonation, when demand will greatly exceed available resources. This article reviews the pertinent literature on radiation injuries from human exposures and animal models to provide a foundation for the triage and management approaches outline...

  15. Pressure loads and structural response of the BNL high-temperature detonation tube

    OpenAIRE

    Shepherd, Joseph E.

    1992-01-01

    The high-temperature detonation tube facility being designed at Brookhaven National Laboratory must withstand dynamic pressure loads. These loads are associated with both detonations and deflagration-to-detonation transition (DDT). The present report documents the results of computations of the pressure loads and structural response. Structural response considerations indicate that radial motion of the tube is sufficiently rapid that the tube actualkly responds to the peak pressure behi...

  16. Volumetric initiation of gaseous detonation by radiant heating of suspended microparticles

    Science.gov (United States)

    Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Yakovenko, I. S.

    2016-02-01

    The concept of detonation wave initiation in the local volume of a fuel-gas mixture containing suspended chemically neutral microparticles heated by radiant energy from an external source is proposed. Mechanisms of initiation of the combustion and detonation waves in a region of accumulation of the radiation- heated microparticles have been studied by numerical simulation methods. Criteria that determine geometric dimensions of a region of the two-phase medium, which are necessary for the initiation of detonation waves, are formulated.

  17. Direct initiation of gaseous detonation via radiative heating of microparticles volumetrically suspended in the gas

    Science.gov (United States)

    Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Yakovenko, I. S.

    2015-11-01

    We propose a new conceptual approach for direct detonation initiation in the gaseous mixtures seeded with micro particles via the radiative heating from the external energy source. The basic mechanisms of energy absorption, ignition and detonation formation are analyzed numerically on the example of hydrogen-oxygen mixture. Obtained data is very promising and allows us to formulate conditions for the source power to ignite detonation in certain system geometry.

  18. Direct-connect performance evaluation of a valveless pulse detonation engine

    OpenAIRE

    Wittmers, Nicole K.

    2004-01-01

    Operational characteristics of a valveless pulse detonation engine system were characterized by experimental measurements of thrust, fuel flow, and internal gas dynamics. The multi-cycle detonation experiments were performed on an axis-symmetric engine geometry operating on an ethylene/air mixtures. The detonation diffraction process from a small 'initiator' combustor to a larger diameter main combustor in a continuous airflow configuration was evaluated during multi-cycle operation of a puls...

  19. Hydrodynamic instabilities in gaseous detonations: comparison of Euler, Navier–Stokes, and large-eddy simulation

    OpenAIRE

    Mahmoudi, Y.; Karimi, N.; Deiterding, R.; Emami, S.

    2014-01-01

    A large-eddy simulation is conducted to investigate the transient structure of an unstable detonation wave in two dimensions and the evolution of intrinsic hydrodynamic instabilities. The dependency of the detonation structure on the grid resolution is investigated, and the structures obtained by large-eddy simulation are compared with the predictions from solving the Euler and Navier–Stokes equations directly. The results indicate that to predict irregular detonation structures in agreement ...

  20. Radioiodine therapy in benign thyroid diseases

    DEFF Research Database (Denmark)

    Bonnema, Steen Joop; Hegedüs, Laszlo

    2012-01-01

    Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems...... of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131...... predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid...

  1. A rare case of benign omentum teratoma

    Directory of Open Access Journals (Sweden)

    Sforza Marcos

    2012-01-01

    Full Text Available Introduction. Mature teratomas (benign cystic teratomas or dermoid cysts are among the most common ovarian tumours; however, teratomas of the omentum and mesentery are extremely rare. Teratoma in the intraperitoneal cavity is uncommon and atypical, and it is even more uncommon in adulthood. Case Outline. An 82-year-old female was admitted to our department with clinical signs of abdominal tumour. The ultrasound scan and preoperative laboratory tests were done. Explorative laparotomy revealed tumour with torsion on its pedicle at the greater omentum. After removal of the mass and the incision a tooth and hair were found, characteristics of teratoma. Conclusion. The excision was very effective and also definitive treatment for this case. The patient recovered well and was discharged 3 days later. The patient probably carried the tumour all her life asymptomatically until admission.

  2. [Benign thyroid nodules: diagnostic and therapeutic approach].

    Science.gov (United States)

    Durante, Cosimo; Cava, Francesco; Paciaroni, Alessandra; Filetti, Sebastiano

    2008-05-01

    In the last years an increase in thyroid nodules detection has been reported from several epidemiological studies. This trend is largely due to the routine use of diagnostic sonography procedures in clinical practice. Thyroid nodules, both palpable or not palpable, rarely turn out to be malignant. Fine-needle aspiration cytology (FNAc) plays a central role in establishing the nature of the nodule. Excluded the presence of malignant lesions, which are generally treated with surgery, physicians are faced with a variety of therapeutic options, and choosing the optimal approach can be a difficult task. These include a periodic follow-up alone without treatment, the iodine supplementation, the thyroid-hormone suppressive therapy, the radioiodine administration, the percutaneous ethanol injections, and the new technique of laser photocoagulation. In all cases, decisions on the management of benign thyroid nodules should always be based on clinical target and a careful analysis of benefits and risks to the patient. PMID:18581970

  3. Climatic variations and benign paroxysmal positional vertigo

    Institute of Scientific and Technical Information of China (English)

    Basil M.N. Saeed; Alyaa Farouk Omari

    2016-01-01

    Benign paroxysmal positional vertigo (BPPV) is probably the most common diagnosis at vertigo clinics. Seasonal cycles of several human illnesses could be attributed variously to changes in atmospheric or weather conditions. In this retrospective study, patients with BPPV from January 2010 to December 2012 were studied, and their charts were reviewed. Statistical analysis revealed a statistically significant difference in patients' numbers among different months of the year. Also there is a significant statistical correlation between the numbers of patients with climatic variations especially the temperature. The present paper discusses the possible explanations for these results which confirms the seasonal variations in BPPV, together with a review of literature to view the possible associations with other disorders that causes such sea-sonality.

  4. The radiation therapy of benign diseases

    International Nuclear Information System (INIS)

    X-ray should only be applied when other forms of treatment of good-natured diseases do not provide equally good results. One should note that somatic lesion should be completely avoided and genetic lesion avoided to the greatest probability. One can distinguish according to ones aims between inflammation irradiation, pain irradiation, stimulation therapy and functional therapy. An indication for inflammation irradiation can be post-operative parotitis, furuncle in the face, mastitis puerperalis, panaritium ossale, recurrent sudoriparouns abscesses and repelling reactions after transplanting organs. Pain irradiation is indicated with degenerative diseases of the skeleton system. A further possible application is radiotherapy of hypotrophic processes and benign tumours. Functional radiotherapy is indicated with hyperendocrinism, neurovegetative disorders and allergies. (MG)

  5. Insights from radiation treatment for benign disease

    Energy Technology Data Exchange (ETDEWEB)

    Bleehen, N.M.

    1987-08-29

    This note compares mortality figures for patients treated with low dose ionizing radiation for benign conditions between the 1920's and 1950's with figures available from the Japanese A-bomb survivors. X radiation for ringworm, ankylosing spondylitis and post-partum mastitis are considered. Figures for leukemia are roughly comparable between radiotherapy groups and A-bomb survivors. Figures for the increased relative risk of breast cancer in spondylitis patients were in marked contrast to bomb survivors who received comparable doses, but compatible with the increase among women given x-rays for acute post-partum mastitis in the 1940's and 1950's. This study also suggests the possibility of different time patterns of risk between different cancers. (U.K.).

  6. Insights from radiation treatment for benign disease

    International Nuclear Information System (INIS)

    This note compares mortality figures for patients treated with low dose ionizing radiation for benign conditions between the 1920's and 1950's with figures available from the Japanese A-bomb survivors. X radiation for ringworm, ankylosing spondylitis and post-partum mastitis are considered. Figures for leukemia are roughly comparable between radiotherapy groups and A-bomb survivors. Figures for the increased relative risk of breast cancer in spondylitis patients were in marked contrast to bomb survivors who received comparable doses, but compatible with the increase among women given x-rays for acute post-partum mastitis in the 1940's and 1950's. This study also suggests the possibility of different time patterns of risk between different cancers. (U.K.)

  7. Benign Duodenocolic Fistula: a Case Report

    Directory of Open Access Journals (Sweden)

    Marzieh Soheili

    2015-10-01

    Full Text Available Benign duodenocolic fistula (DCF, known as a fistula between the duodenum and colon with orwithout cecum of nonmalignant origin, is an unusual complication of different gastrointestinal diseases. Thepresent paper records a case in which the patient presented with chronic diarrhea, abdominal pain, weight lossas well as having a history of gastric ulcer. Most frequently the condition presents with signs ofmalabsorption such as weight loss and diarrhea, but other symptoms include nausea, vomiting (sometimeswith fecal, and abdominal pain. Gastrointestinal inflammatory conditions are the usual causes. The mostcommon ones are perforated duodenal ulcer and Crohn’s disease. Barium enemas are usually diagnostic.Treatment consists of excising the fistula and repairing the duodenal and colonic defects. Closure of thefistula provides quick relief.

  8. Palladium-Catalyzed Environmentally Benign Acylation.

    Science.gov (United States)

    Suchand, Basuli; Satyanarayana, Gedu

    2016-08-01

    Recent trends in research have gained an orientation toward developing efficient strategies using innocuous reagents. The earlier reported transition-metal-catalyzed carbonylations involved either toxic carbon monoxide (CO) gas as carbonylating agent or functional-group-assisted ortho sp(2) C-H activation (i.e., ortho acylation) or carbonylation by activation of the carbonyl group (i.e., via the formation of enamines). Contradicting these methods, here we describe an environmentally benign process, [Pd]-catalyzed direct carbonylation starting from simple and commercially available iodo arenes and aldehydes, for the synthesis of a wide variety of ketones. Moreover, this method comprises direct coupling of iodoarenes with aldehydes without activation of the carbonyl and also without directing group assistance. Significantly, the strategy was successfully applied to the synthesis n-butylphthalide and pitofenone. PMID:27377566

  9. Benign meningiomas: primary treatment selection affects survival

    International Nuclear Information System (INIS)

    Purpose: To examine the effect of primary treatment selection on outcomes for benign intracranial meningiomas at the University of Florida. Methods and Materials: For 262 patients, the impact of age, Karnofsky performance status, pathologic features, tumor size, tumor location, and treatment modality on local control and cause-specific survival was analyzed (minimum potential follow-up, 2 years; median follow-up, 8.2 years). Extent of surgery was classified by Simpson grade. Treatment groups: surgery alone (n = 229), surgery and postoperative radiotherapy (RT) (n = 21), RT alone (n = 7), radiosurgery alone (n = 5). Survival analysis: Kaplan-Meier method with univariate and multivariate analysis. Results: At 15 years, local control was 76% after total excision (TE) and 87% after subtotal excision plus RT (SE+RT), both significantly better (p = 0.0001) than after SE alone (30%). Cause-specific survival at 15 years was reduced after treatment with SE alone (51%), compared with TE (88%) or SE+RT (86%) (p = 0.0003). Recurrence after primary treatment portended decreased survival, independent of initial treatment group or salvage treatment selection (p = 0.001). Atypical pathologic features predicted reduced 15-year local control (54 vs. 71%) and cause-specific survival rates (57 vs. 86%). Multivariate analysis for cause-specific survival revealed treatment group (SE vs. others; p = 0.0001), pathologic features (atypical vs. typical; p = 0.0056), and Karnofsky performance status (≥80 vs. <80; p = 0.0153) as significant variables. Conclusion: Benign meningiomas are well managed by TE or SE+RT. SE alone is inadequate therapy and adversely affects cause-specific survival. Atypical pathologic features predict a poorer outcome, suggesting possible benefit from more aggressive treatment. Because local recurrence portends lower survival rates, primary treatment choice is important

  10. Shock-to-detonation transition in solid heterogeneous explosives; La transition choc-detonation dans les explosifs solides heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Belmas, R.

    2003-07-01

    This paper is an overview of the studies performed during the last decades on the shock-to-detonation transition process in heterogeneous explosives. We present the experimental and theoretical approaches mentioned in the literature and/or developed at CEA/DAM. The aim is to identify which main mechanisms govern this transition process and to evaluate the relevance of the available modeling tools. (author)

  11. Influence of interatomic bonding potentials on detonation properties.

    Science.gov (United States)

    Heim, Andrew J; Grønbech-Jensen, Niels; Germann, Timothy C; Holian, Brad Lee; Kober, Edward M; Lomdahl, Peter S

    2007-08-01

    The dependences of the macroscopic detonation properties of a two-dimensional (2D) diatomic (AB) molecular system on the fundamental molecular properties were investigated. This includes examining the detonation velocity, reaction zone thickness, and critical width as functions of the exothermicity (Q) of the gas-phase reaction [AB --> (1/2)(A(2) + B(2))] and the gas-phase dissociation energy (D(e)(AB)) for AB --> A + B . Following previous work, molecular dynamics (MD) simulations with a reactive empirical bond-order potential were used to characterize the shock-induced response of a diatomic AB molecular solid, which exothermically reacts to produce A2 and B2 gaseous products. Nonequilibrium MD simulations reveal that there is a linear dependence between the square of the detonation velocity and both of these molecular parameters. The detonation velocities were shown to be consistent with the Chapman-Jouguet (CJ) model, demonstrating that these dependences arise from how the equation of state of the products and reactants are affected. Equilibrium MD simulations of microcanonical ensembles were used to determine the CJ states for varying Q 's, and radial distribution functions characterize the atomic structure. The character of this material near the CJ conditions was found to be somewhat unusual, consisting of polyatomic clusters rather than discrete molecular species. It was also found that there was a minimum value of Q and a maximum value of (D(e)(AB)) for which a pseudo-one-dimensional detonation could not be sustained. The reaction zone of this material was characterized under both equilibrium (CJ) and transient (underdriven) conditions. The basic structure is consistent with the Zeldovich-von Neumann-Döring model, with a sharp shock rise and a reaction zone that extends to 200-300 Angstrom. The underdriven systems show a buildup process which requires an extensive time to approach equilibrium conditions. The rate stick failure diameter (critical width in

  12. Influence of carbon monoxide additions on the sensitivity of the dry hydrogen-air mixtures to detonation

    International Nuclear Information System (INIS)

    Under severe accident conditions of water cooled nuclear reactors the hydrogen-air detonation represents one of the most hazardous events which can result in the reactor containment damage. An important factor related with the measure of gas mixture detonability is the detonation cell size which correlates with the critical tube diameter and detonation initiation energy. A numerical kinetic study is presented of the influence of carbon monoxide admixtures (from 0 vol.% to 40 vol.%) upon the sensitivity (detonation cell size) of the dry hydrogen-air gas mixtures to detonation in post-accident containment atmosphere. (author). 3 refs., 3 figs

  13. Nano-scale spinning detonation in a condensed phase energetic material

    International Nuclear Information System (INIS)

    A single-headed spinning detonation wave is observed in molecular dynamics simulations of a condensed phase detonation of an energetic material confined to a round tube. The EM is modeled using a modified AB reactive empirical bond order (REBO) potential. The simulated spinning detonation is similar to those observed in the gas phase. However, in addition to the incident, oblique, and transverse shock waves well known from gas-phase spinning detonations, a contact shock wave generated by a contact discontinuity is uncovered in our MD simulations.

  14. Unsteady self-sustained detonation waves in flake aluminum dust/air mixtures

    OpenAIRE

    Liu, Qingming; Huang, Jinxiang; Zhang, Yunming; Li, Shuzhuan

    2015-01-01

    Self-sustained detonation waves in flake aluminum dust/air mixtures have been studied in a tube of diameter 199 mm and length 32.4 m. A pressure sensor array of 32 sensors mounted around certain circumferences of the tube was used to measure the shape of the detonation front in the circumferential direction and pressure histories of the detonation wave. A two-head spin detonation wave front was observed for the aluminum dust/air mixtures, and the cellular structure resulting from the spinning...

  15. Detonation in hydrogen–nitrous oxide–diluent mixtures: An experimental and numerical study

    OpenAIRE

    Mével, Rémy; Davidenko, Dmitry; Lafosse, Fabien; Chaumeix, Nabiha; Dupré, Gabrielle; Paillard, Claude-Étienne; Shepherd, Joseph E.

    2015-01-01

    Knowledge of H_2–N_2O mixtures explosive properties is important to the safety of nuclear waste storage and semi-conductor manufacturing processes. The present study provides new experimental data on H_2–N_2O detonations, and proposes a thermochemical model which is used to numerically simulate detonation propagation. Detonation cell size has been measured in a variety of H_2–N_2O–Ar mixtures. Even at low initial pressure, these mixtures are very sensitive to detonation with cell size of few ...

  16. Hydrodynamic instabilities and transverse waves in propagation mechanism of gaseous detonations

    Science.gov (United States)

    Mahmoudi, Y.; Mazaheri, K.; Parvar, S.

    2013-10-01

    The present study examines the role of transverse waves and hydrodynamic instabilities mainly, Richtmyer-Meshkov instability (RMI) and Kelvin-Helmholtz instability (KHI) in detonation structure using two-dimensional high-resolution numerical simulations of Euler equations. To compare the numerical results with those of experiments, Navier-Stokes simulations are also performed by utilizing the effect of diffusion in highly irregular detonations. Results for both moderate and low activation energy mixtures reveal that upon collision of two triple points a pair of forward and backward facing jets is formed. As the jets spread, they undergo Richtmyer-Meshkov instability. The drastic growth of the forward jet found to have profound role in re-acceleration of the detonation wave at the end of a detonation cell cycle. For irregular detonations, the transverse waves found to have substantial role in propagation mechanism of such detonations. In regular detonations, the lead shock ignites all the gases passing through it, hence, the transverse waves and hydrodynamic instabilities do not play crucial role in propagation mechanism of such regular detonations. In comparison with previous numerical simulations present simulation using single-step kinetics shows a distinct keystone-shaped region at the end of the detonation cell.

  17. Detonation charge size versus coda magnitude relations in California and Nevada

    Science.gov (United States)

    Brocher, T.M.

    2003-01-01

    Magnitude-charge size relations have important uses in forensic seismology and are used in Comprehensive Nuclear-Test-Ban Treaty monitoring. I derive empirical magnitude versus detonation-charge-size relationships for 322 detonations located by permanent seismic networks in California and Nevada. These detonations, used in 41 different seismic refraction or network calibration experiments, ranged in yield (charge size) between 25 and 106 kg; coda magnitudes reported for them ranged from 0.5 to 3.9. Almost all represent simultaneous (single-fired) detonations of one or more boreholes. Repeated detonations at the same shotpoint suggest that the reported coda magnitudes are repeatable, on average, to within 0.1 magnitude unit. An empirical linear regression for these 322 detonations yields M = 0.31 + 0.50 log10(weight [kg]). The detonations compiled here demonstrate that the Khalturin et al. (1998) relationship, developed mainly for data from large chemical explosions but which fits data from nuclear blasts, can be used to estimate the minimum charge size for coda magnitudes between 0.5 and 3.9. Drilling, loading, and shooting logs indicate that the explosive specification, loading method, and effectiveness of tamp are the primary factors determining the efficiency of a detonation. These records indicate that locating a detonation within the water table is neither a necessary nor sufficient condition for an efficient shot.

  18. [The Diagnostics of Detonation Flow External Field Based on Multispectral Absorption Spectroscopy Technology].

    Science.gov (United States)

    Lü, Xiao-jing; Li, Ning; Weng, Chun-sheng

    2016-03-01

    Compared with traditional sampling-based sensing method, absorption spectroscopy technology is well suitable for detonation flow diagnostics, since it can provide with us fast response, nonintrusive, sensitive solution for situ measurements of multiple flow-field parameters. The temperature and concentration test results are the average values along the laser path with traditional absorption spectroscopy technology, while the boundary of detonation flow external field is unknown and it changes all the time during the detonation engine works, traditional absorption spectroscopy technology is no longer suitable for detonation diagnostics. The trend of line strength with temperature varies with different absorption lines. By increasing the number of absorption lines in the test path, more information of the non-uniform flow field can be obtained. In this paper, based on multispectral absorption technology, the reconstructed model of detonation flow external field distribution was established according to the simulation results of space-time conservation element and solution element method, and a diagnostic method of detonation flow external field was given. The model deviation and calculation error of the least squares method adopted were studied by simulation, and the maximum concentration and temperature calculation error was 20.1% and 3.2%, respectively. Four absorption lines of H2O were chosen and detonation flow was scanned at the same time. The detonation external flow testing system was set up for the valveless gas-liquid continuous pulse detonation engine with the diameter of 80 mm. Through scanning H2O absorption lines with a high frequency of 10 kHz, the on-line detection of detonation external flow was realized by direct absorption method combined with time-division multiplexing technology, and the reconstruction of dynamic temperature distribution was realized as well for the first time, both verifying the feasibility of the test method. The test results

  19. The Ignition of Carbon Detonations via Converging Shock Waves in White Dwarfs

    OpenAIRE

    Shen, Ken J.; Bildsten, Lars

    2013-01-01

    The progenitor channel responsible for the majority of Type Ia supernovae is still uncertain. One emergent scenario involves the detonation of a He-rich layer surrounding a C/O white dwarf, which sends a shock wave into the core. The quasi-spherical shock wave converges and strengthens at an off-center location, forming a second, C-burning, detonation that disrupts the whole star. In this paper, we examine this second detonation of the double detonation scenario using a combination of analyti...

  20. Dynamics of the formation of the condensed phase particles at detonation of high explosives

    International Nuclear Information System (INIS)

    The article presents the results of the experimental study SAXS on condensed carbon particles that appear at the detonation of a high explosive. It was shown that the SAXS signal rises for 1.5-4 μs after the detonation front passing. The SAXS signal in trotyl and its alloys with hexogen starts just after the compression of the material in the detonation wave. In octogen, hexogen and PETN, the SAXS signal appears in 0.5 μs and is much smaller than the signal at the detonation of trotyl and its alloys with hexogen

  1. Application of a Schlieren diagnostic to the behavior of exploding bridge wire and laser detonators

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Michael J [Los Alamos National Laboratory; Clarke, Steven A [Los Alamos National Laboratory; Munger, Alan C [Los Alamos National Laboratory; Thomas, Keith A [Los Alamos National Laboratory

    2009-01-01

    Even though the exploding bridge wire (EBW) detonator has been in use for over 60 years, there are still discussions about the mechanism for achieving detonation. Los Alamos has been developing a high-power laser detonator to function in a manner similar to an EBW. Schlieren imaging techniques are applied to laser-driven detonator output in polydimethylsiloxane (POMS) samples to investigate the time-dependent geometry of the shock wave and to obtain instantaneous measurements of shock-front velocity. Velocity Hugoniot data are used to convert measured shock velocities to corresponding particle velocities, allowing instantaneous shock pressures to be obtained via Rankine-Hugoniot relations across the shock.

  2. Preparation and characterization of nanosized TiO2 powders by gaseous detonation method

    International Nuclear Information System (INIS)

    Nanosized TiO2 powders were prepared for the first time by gaseous detonation method. The structure, composition and size distribution of the detonation product were systematically characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicate the powders are a mixed crystal of rutile and anatase exhibiting non-spherical grains, and the average size of particles was between 20 and 40 nm. The results of detonation pressure measurement show that the reaction took place under a deflagration-to-detonation transition (DDT) course

  3. Space Shuttle Main Engine fuel preburner augmented spark igniter shutdown detonations

    Science.gov (United States)

    Dexter, C. E.; Mccay, T. D.

    1986-01-01

    Detonations were experienced in the Space Shuttle Main Engine fuel preburner (FPB) augmented spark igniter (ASI) during engine cutoff. Several of these resulted in over pressures sufficient to damage the FPB ASI oxidizer system. The detonations initiated in the FPB ASI oxidizer line when residual oxidizer (oxygen) in the line mixed with backflowing fuel (hydrogen) and detonated. This paper reviews the damage history to the FPB ASI oxidizer system, an engineering assessment of the problem cause, a verification of the mechanisms, the hazards associated with the detonations, and the solution implemented.

  4. Material properties effects on the detonation spreading and propagation of diaminoazoxyfurazan (DAAF)

    Energy Technology Data Exchange (ETDEWEB)

    Francois, Elizabeth Green [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory; Novak, Alan M [Los Alamos National Laboratory; Kennedy, James E [HERE LLC

    2010-01-01

    Recent dynamic testing of Diaminoazoxyfurazan (DAAF) has focused on understanding the material properties affecting the detonation propagation, spreading, behavior and symmetry. Small scale gap testing and wedge testing focus on the sensitivity to shock with the gap test including the effects of particle size and density. Floret testing investigates the detonation spreading as it is affected by particle size, density, and binder content. The polyrho testing illustrates the effects of density and binder content on the detonation velocity. Finally the detonation spreading effect can be most dramatically seen in the Mushroom and Onionskin tests where the variations due to density gradients, pressing methods and geometry can be seen on the wave breakout behavior.

  5. Instability Criterion of One-Dimensional Detonation Wave with Three-Step Chain Branching Reaction Model

    Institute of Scientific and Technical Information of China (English)

    TENG Hong-Hui; JIANG Zong-Lin

    2011-01-01

    @@ One-dimensional detonation waves are simulated with the three-step chain branching reaction model, and the instability criterion is studied.The ratio of the induction zone length and the reaction zone length may be used to decide the instability, and the detonation becomes unstable with the high ratio.However, the ratio is not invariable with different heat release values.The critical ratio, corresponding to the transition from the stable detonation to the unstable detonation, has a negative correlation with the heat release.An empirical relation of the Chapman-Jouguet Mach number and the length ratio is proposed as the instability criterion.

  6. MRI of vertebral compression fracture: benign versus metastasis

    International Nuclear Information System (INIS)

    The study was performed to evaluate differentiating features of spinal compression fractures between benign and metastatic lesions. We reviewed MR imaging in 52 patients (benign 38, metastasis 14) with vertebral compression fracture. Signal intensity of fracture and uninvolved areas, presence of contrast enhancement fragmentation, and paravertebral mass were analyzed retrospectively. Signal intensity of fracture site was variable in benign lesions, but low signal intensity on T1-weighted image and high on T2-weighted image were seen in all cases of metastasis. Signal intensity of uninvolved area was high on T1-weighted image and low on T2-weighted image in 84% of benign lesions. On the contrary, normal marrow signal intensity was not seen in the uninvolved areas of all metastatic fractures. Contrast enhancement were observed in all cases of benign and metastatic compression fractures. Fragmentation were seen in 1 case of metastasis (7%) and in 11 cases of benign lesions (29%). Paravertebral mass were seen in 5 cases of metastasis (36%) and in 7 cases of benign lesions (18%). Presence of normal marrow signal intensity in the uninvolved area of fracture site could be the most useful sign for differentiating benign causes from metastasis

  7. [Treatment of benign laryngeal diseases using a CO2 laser].

    Science.gov (United States)

    Betka, J; Klozar, J; Kasík, P; Taudy, M; Tichý, S

    1989-05-01

    CO2 laser surgery is becoming a part of larynx surgery. The authors inform about their experience in benign larynx tumours treatment. They present analysis of concrete therapeutic procedures in individual larynx affections. They conclude that laser surgery is an advantegous method for benign larynx tumours treatment. PMID:2772545

  8. Hibernoma: imaging characteristics of a rare benign soft tissue tumor

    International Nuclear Information System (INIS)

    Hibernoma is a rare benign soft tissue tumor of brown fat. Awareness of the MR imaging appearances of this lesion may allow for improved preoperative diagnosis or at least inclusion of hibernoma as a possible benign differential diagnosis prior to surgery. (orig.)

  9. [Research on diagnosis of gas-liquid detonation exhaust based on double optical path absortion spectroscopy technique].

    Science.gov (United States)

    Lü, Xiao-Jing; Li, Ning; Weng, Chun-Sheng

    2014-03-01

    The effect detection of detonation exhaust can provide measurement data for exploring the formation mechanism of detonation, the promotion of detonation efficiency and the reduction of fuel waste. Based on tunable diode laser absorption spectroscopy technique combined with double optical path cross-correlation algorithm, the article raises the diagnosis method to realize the on-line testing of detonation exhaust velocity, temperature and H2O gas concentration. The double optical path testing system is designed and set up for the valveless pulse detonation engine with the diameter of 80 mm. By scanning H2O absorption lines of 1343nm with a high frequency of 50 kHz, the on-line detection of gas-liquid pulse detonation exhaust is realized. The results show that the optical testing system based on tunable diode laser absorption spectroscopy technique can capture the detailed characteristics of pulse detonation exhaust in the transient process of detonation. The duration of single detonation is 85 ms under laboratory conditions, among which supersonic injection time is 5.7 ms and subsonic injection time is 19.3 ms. The valveless pulse detonation engine used can work under frequency of 11 Hz. The velocity of detonation overflowing the detonation tube is 1,172 m x s(-1), the maximum temperature of detonation exhaust near the nozzle is 2 412 K. There is a transitory platform in the velocity curve as well as the temperature curve. H2O gas concentration changes between 0-7% during detonation under experimental conditions. The research can provide measurement data for the detonation process diagnosis and analysis, which is of significance to advance the detonation mechanism research and promote the research of pulse detonation engine control technology. PMID:25208369

  10. 环形爆震波聚焦起爆数值模拟%Numerical simulation of detonation initiation in a duct via imploding annular detonation

    Institute of Scientific and Technical Information of China (English)

    秦亚欣; 高歌

    2011-01-01

    Computational simulations on detonation duct with different annular pre-detonators were carried out to study the phenomena, mechanism and gas dynamics characteristic of annular detonation initiation. Two-dimensional axisymmetric and unsteady Navier-Stokes equations were numerically simulated, and detailed chemical reaction kinetics of hydrogen/air mixture was used. The results of numerical simulation show that laminar flame generated by low energy ignition in annular pre-detonator accelerates under the narrow channel, and then forms annular detonation via deflagration to detonation transition. Annular detonation detonates the combustible mixture in the main detonation chamber after reflection and imploding at the axis. Contrastive research on the distance and intensity of stable detonation was analyzed. Through calculation and analysis, it provided a deep understanding on the aerodynamics characteristic of annular detonation wave diffraction, reflection and imploding and the development of complex wave in the transitional region, laying a theory basis for detonation initiation and useful information to further experiment.%对三种带不同结构形式的环形预爆管的爆震发生器进行了数值模拟,来研究环形爆震波聚焦起爆现象及其气动特性.数值计算采用多组分理想气体详细的化学反应机理、二维轴对称非定常流动的NavierStokes方程来模拟化学动力学和流体动力学过程.研究发现用低的点火能量对环形预爆管中的燃料和氧化剂点火产生层流火焰,层流火焰在狭窄管壁的作用下完成爆燃向爆震转捩,形成环形爆震波,环形爆震波在聚焦腔经过反射、汇聚,最终引爆主爆震室中的可燃混合物;并对稳定爆震的距离和强度进行了对比研究.通过分析对环形爆震波衍射、反射、聚焦的气体动力学特性及复杂波系发展规律有了更深的认识,为进一步试验提供参考.

  11. Benign Biliary Strictures: Diagnostic Evaluation and Approaches to Percutaneous Treatment.

    Science.gov (United States)

    Fidelman, Nicholas

    2015-12-01

    Interventional radiologists are often consulted to help identify and treat biliary strictures that can result from a variety of benign etiologies. Mainstays of noninvasive imaging for benign biliary strictures include ultrasound, contrast-enhanced computed tomography and magnetic resonance imaging, magnetic resonance cholangiopancreatography, and computed tomography cholangiography. Endoscopic retrograde cholangiography is the invasive diagnostic procedure of choice, allowing both localization of a stricture and treatment. Percutaneous biliary interventions are reserved for patients who are not candidates for endoscopic retrograde cholangiography (eg, history of distal gastrectomy and biliary-enteric anastomosis to a jejunal roux limb). This review discusses the roles of percutaneous transhepatic cholangiography and biliary drainage in the diagnosis of benign biliary strictures. The methodology for crossing benign biliary strictures, approaches to balloon dilation, management of recalcitrant strictures (ie, large-bore biliary catheters and retrievable covered stents), and the expected outcomes and complications of percutaneous treatment of benign biliary strictures are also addressed. PMID:26615161

  12. Plasma-assisted ignition and deflagration-to-detonation transition.

    Science.gov (United States)

    Starikovskiy, Andrey; Aleksandrov, Nickolay; Rakitin, Aleksandr

    2012-02-13

    Non-equilibrium plasma demonstrates great potential to control ultra-lean, ultra-fast, low-temperature flames and to become an extremely promising technology for a wide range of applications, including aviation gas turbine engines, piston engines, RAMjets, SCRAMjets and detonation initiation for pulsed detonation engines. The analysis of discharge processes shows that the discharge energy can be deposited into the desired internal degrees of freedom of molecules when varying the reduced electric field, E/n, at which the discharge is maintained. The amount of deposited energy is controlled by other discharge and gas parameters, including electric pulse duration, discharge current, gas number density, gas temperature, etc. As a rule, the dominant mechanism of the effect of non-equilibrium plasma on ignition and combustion is associated with the generation of active particles in the discharge plasma. For plasma-assisted ignition and combustion in mixtures containing air, the most promising active species are O atoms and, to a smaller extent, some other neutral atoms and radicals. These active particles are efficiently produced in high-voltage, nanosecond, pulse discharges owing to electron-impact dissociation of molecules and electron-impact excitation of N(2) electronic states, followed by collisional quenching of these states to dissociate the molecules. Mechanisms of deflagration-to-detonation transition (DDT) initiation by non-equilibrium plasma were analysed. For longitudinal discharges with a high power density in a plasma channel, two fast DDT mechanisms have been observed. When initiated by a spark or a transient discharge, the mixture ignited simultaneously over the volume of the discharge channel, producing a shock wave with a Mach number greater than 2 and a flame. A gradient mechanism of DDT similar to that proposed by Zeldovich has been observed experimentally under streamer initiation. PMID:22213667

  13. Transurethral microwave thermotherapy for benign prostatic hyperplasia

    Directory of Open Access Journals (Sweden)

    Rubeinstein Jonathan N.

    2003-01-01

    Full Text Available Transurethral resection of the prostate (TURP remains the gold standard for treatment of benign prostatic hyperplasia (BPH. In general, while this procedure is safe, patients require a spinal, epidural, or general anesthesia and often several days of hospital stay; the potential morbidity and mortality limits the use of TURP in high-risk patients. Pharmacotherapy has been recommended as a first-line therapy for all patients with mild to moderate symptoms. Patients are oftentimes enthusiastic if they are offered a one-time method to treat lower urinary tract symptoms secondary to BPH, provided that the method offers reduced risk and allows an efficacy equal to that of medical therapy. One such method is transurethral microwave thermotherapy (TUMT. TUMT involves the insertion of a specially designed urinary catheter with a microwave antenna, which heats the prostate and destroys hyperplastic prostate tissue. TUMT allows the avoidance of general or regional anesthesia, and results in minimal blood loss and fluid absorption. In this review, the authors discussed the current indications and outcome of TUMT, including the history of the procedure, the mechanism of action, the indications for TUMT, the pre-operative considerations, the patient selection, the results in terms of efficacy, by comparing TUMT vs. Sham, TUMT vs. Alpha-blocker and TUMT vs. TURP. Finally, the complications are presented, as well as other uses and future directions of the procedure. The authors concluded that TUMT is a safe and effective minimally invasive alternative to treatment of symptomatic BPH.

  14. Benign disease of the common bile duct.

    Science.gov (United States)

    Saxena, R; Pradeep, R; Chander, J; Kumar, P; Wig, J D; Yadav, R V; Kaushik, S P

    1988-08-01

    The incidence of common bile duct (CBD) pathology in a group of patients with benign biliary disease (n = 505) was found to be 23.2 per cent. The spectrum included 111 patients (90.2 per cent) with CBD stones, 37 of whom (33.3 per cent) had no symptoms or findings pre-operatively indicating CBD involvement. Five patients had papillary stenosis, three had postoperative CBD strictures, one had a choledochal cyst and one had an external biliary fistula. Of the 100 CBDs measuring more than 10 mm in diameter, 90 harboured calculi. In the remaining 23 CBDs measuring less than 10 mm, calculi were present in 21. The presence of CBD calculi was demonstrated by intra-operative cholangiography in 49 patients. In the remaining patients (n = 74), the diagnosis of CBD pathology was made either by percutaneous transhepatic cholangiography, endoscopic retrograde cholangio-pancreatography, T-tube cholangiography or peroperative palpation. The surgical procedures performed included choledochotomy and T-tube drainage (n = 74), transduodenal sphincteroplasty (n = 27) and choledochoduodenostomy (n = 18). The overall mortality and morbidity of CBD exploration was 3.3 per cent and 24.4 per cent respectively, which was significantly greater than that for cholecystectomy alone (0.3 per cent and 8.6 per cent respectively). Transduodenal sphincteroplasty carried a much higher mortality (11 per cent) and morbidity (52 per cent) when compared with other procedures. PMID:3167536

  15. Benign and pathological electrocardiographic changes in athletes.

    Science.gov (United States)

    Machado, Marino; Vaz Silva, Manuel

    2015-12-01

    Sudden cardiac death is the leading cause of death in athletes during sport. It is a tragic event that generates significant media attention and discussion throughout society as to whether everything possible had been done to prevent it. Regular physical exercise causes cardiac remodeling at both the mechanical and electrical level, known as athlete's heart, resulting in an electrocardiogram (ECG) considered abnormal compared with the ECGs of the general population. Some of these electrocardiographic changes are considered normal or physiological in athletes, while others suggest underlying cardiac disease with the potential to cause sudden cardiac death. There is thus an urgent need to define the electrocardiographic patterns that allow or prohibit participation in sports, and to differentiate them in terms of gender, ethnicity and age. The purpose of this review is to present the latest data on the electrocardiographic changes considered benign or pathological that are typically found in athletes and to critically analyze the most recent criteria for classifying ECGs in this population (the Seattle criteria), comparing them with previous guidelines and with the latest studies on the subject. This article also examines the question of including ECGs in pre-participation screening programs, the US and European approaches to the subject, and the most up-to-date data on the sensitivity, specificity and cost-effectiveness of the ECG in athletes. PMID:26643438

  16. [Pharmacological treatment of benign prostatic hyperplasia].

    Science.gov (United States)

    Oelke, M; Martinelli, E

    2016-01-01

    The pharmacological treatment of benign prostatic hyperplasia (BPH) is indicated when men suffer from lower urinary tract symptoms (LUTS) but there are no absolute indications for prostate surgery or severe bladder outlet obstruction. Phytotherapy can be used in men with mild to moderate LUTS and alpha-blockers can quickly and effectively decrease the LUTS and symptomatic disease progression. Phosphodiesterase type 5 inhibitors (PDE5-I) are an alternative to alpha-blockers when men experience bothersome side effects from alpha-blockers or erectile dysfunction. If patients predominantly have bladder storage symptoms and a small prostate, muscarinic receptor antagonists are a viable treatment option. The combination of alpha-blocker plus muscarinic receptor antagonist is more efficacious in reducing LUTS than the single drugs alone. The 5 alpha-reductase inhibitors (5ARI) can significantly decrease LUTS and disease progression (e.g. acute urinary retention and need for prostate surgery) in men with larger prostates (> 30-40 ml). The combination of 5ARI plus alpha-blocker can reduce LUTS and disease progression more effectively than drug monotherapy. Combination therapy with PDE5-I (tadalafil) plus 5ARI (finasteride) reduces LUTS more substantially than 5ARI alone and, additionally, PDE5-Is reduce the sexual side effects during 5ARI treatment. PMID:26676726

  17. Balloon catheter dilatation of benign urethral strictures

    International Nuclear Information System (INIS)

    The authors report their experience of benign urethral stricture dilatation by balloon catheter in 11 male patients. Ten posterior and 2 anterior urethral strictures were treated; in 1 patients several narrowings coexisted at various levels. Etiology was inflammatory in 4 cases, iatrogen in 3, post-traumatic in 2, and equivocal in 2. The patients were studied both before and soon after dilatation by means of retrograde and voiding cystourethrogram and uroflowgraphy; the follow-up (2-14 months) was performed by urodynamic alone. In all cases, dilatation was followed by the restoration of urethral gauge, together with prompt functional improvement of urodynamic parameters. The latter result subsisted in time in 9 patients. In 2 cases recurrences were observed demonstrated at once by clinics and urodynamics. Both lesions were successfully re-treated. Neither early not late complication occurred. In spite of the limited material, the valuable results obtained, together with the absence of complications, the peculiar morphology of recurrences, and the chance of repeating it make the procedure advisable as a valid alternative to conventional techniques for these pathologies

  18. Visual laser coagulation for benign prostatic hyperplasia

    International Nuclear Information System (INIS)

    A total of 28 patients with symptomatic bladder outlet obstruction due to benign prostatic hyperplasia were treated by visual laser coagulation (VLAP) performed with the Myriadlase side-firing neodymium: YAG laser fibre at 40 watts power. The treatment was performed as an outpatient procedure using intraurethral gel anaesthesia and light intravenous sedation and analgesia. Prostatic volume was 32 g and 650 joule per gram prostatic tissue was administered. The patients were evaluated at mean 9.2 weeks. The mean operative time was 34 minutes. The procedure was very gentle, all patients tolerated it well and there was no bleeding. Most patients experienced some dysuria for three to four weeks after the procedure, two had severe symptoms. Two patients remained in retention and required transurethral resection. The rest expressed subjective satisfaction with the results. Peak urinary flow increased from mean 9.0 ml/sec preoperatively to 15.4 ml/sec; a mean increase of 78%. One patients developed clinical urinary tract infection. There were no other complications of clinical significance. 19 refs., 1 fig

  19. Perspectives of radiation therapy in benign diseases

    International Nuclear Information System (INIS)

    Purpose: the numbers of patients with nonmalignant diseases referred for radiation therapy had to be evaluated for the last 4 years. Patients and methods: in the years 2002, 2004, and 2005 radiation therapy was performed in 61, 40, and 26 patients, respectively. Regularly, more women than men were treated, median age annually was 57, 54, and 55 years, respectively (table 1). The radiotherapy scheme was not modified within the evaluated period. Results: the proportion of nonmalignant diseases among all patients treated decreased from 4.7% in 2002 to 3.3% in 2004 and 2.2% in 2005, respectively. A shift was noticed toward the treatment of four main diseases (endocrine orbitopathy, prevention of heterotopic ossification, meningeoma, tendinitis, table 2). The number of referring physicians decreased from 19 to six. Conclusion: due to administrative restrictions for treatment in hospitals, budget restrictions in private practices and lasting, insufficient revenues for radiotherapy in nonmalignant diseases, radiation therapy for the entire group of benign diseases is endangered. (orig.)

  20. Skin conditions: benign nodular skin lesions.

    Science.gov (United States)

    Nguyen, Tam; Zuniga, Ramiro

    2013-04-01

    Benign subcutaneous lesions are a common reason that patients visit family physicians. Lipomas are the most common of these lesions; they most often occur on the trunk and proximal extremities. Recent data show that as many as half of the fat cells in lipomas are atypical. Ultrasound is used increasingly to confirm lipoma diagnosis, but deep lesions should be evaluated with magnetic resonance imaging study or computed tomography scan to exclude involvement of underlying structures and/or liposarcoma. Small lesions can sometimes be managed with serial injections of midpotency steroids. Larger lesions (larger than 5 cm), those compressing other structures, or those suspicious for malignancy should be excised using standard surgical excision or, when possible, the newer minimal-scar segmental extraction technique. Ganglion cysts are another common lesion, the presence of which often is confirmed with ultrasound if the diagnosis is not clinically apparent. Management includes splinting, aspiration, and/or injection of steroids, with or without hyaluronidase. Epidermal inclusion cysts, also called sebaceous cysts, typically are asymptomatic unless they become infected. Ultrasound can aid in diagnosis. The only definitive management is surgical excision with complete removal of the cyst wall or capsule, using minimal-scar segmental extraction or conventional surgical removal. PMID:23600336

  1. Smoking habit and benign breast disease

    International Nuclear Information System (INIS)

    The possible association between cigarette smoking and the risk of benign breast disease (BBD) was assessed in a case-control study conducted in Gdansk, Poland, between 1990 and 1994. The study compared 160 women with newly diagnosed BBD admitted to the Gdansk Cancer Outpatients Clinic and 160 controls, women from outpatients clinics at the Medical University of Gdansk. There was no convincing evidence of an association, either positive or negative, between various indicators of smoking habit (smoking status, number of cigarettes smoked per day, duration of smoking) and the risk of BBD. Slightly lower relative risk (RRs) of BBD in ex-smokers of 10 or more cigarettes per day (RR = 0.9; 95% confidence interval, CI: 0.4-2.2), and with duration of smoking >= (RR = 0.1-3.4), were also observed in current smokers (RR = 0.8; 95% CI: 0.4-1.5), and (RR = 0.8; 95% CI: 0.1-3.4), but these findings were not statistically significant. (author)

  2. Geometric Scaling for a Detonation Wave Governed by a Pressure-Dependent Reaction Rate and Yielding Confinement

    OpenAIRE

    Li, Jianling; Mi, XiaoCheng; Higgins, Andrew J.

    2014-01-01

    The propagation of detonation waves in reactive media bounded by an inert, compressible layer is examined via computational simulations in two different geometries, axisymmetric cylinders and two dimensional, planar slabs. For simplicity, an ideal gas equation of state is used with a pressure-dependent reaction rate that results in a stable detonation wave structure. The detonation is initiated as an ideal Chapman-Jouguet (CJ) detonation with a one-dimensional structure, and then allowed to p...

  3. Double-detonation explosions as progenitors of type Iax supernovae

    OpenAIRE

    Wang, Bo; Justham, Stephen; Han, Zhanwen

    2013-01-01

    It has recently been proposed that one sub-class of type Ia supernovae (SNe Ia) is sufficiently both distinct and common to be classified separately from the bulk of SNe Ia, with a suggested class name of "type Iax supernovae" (SNe Iax), after SN 2002cx. We show that the population properties of this class can be understood if the events originate from helium double-detonation sub-Chandrasekhar mass explosions, in which a carbon--oxygen white dwarf (CO WD) accumulates a helium layer from a no...

  4. Deflagration-to-Detonation Transition in Unconfined Media

    Science.gov (United States)

    Poludnenko, Alexei; Gardiner, Thomas; Oran, Elaine

    2011-11-01

    Deflagration-to-detonation transition (DDT) can occur in environments ranging from experimental and industrial systems on Earth to astrophysical thermonuclear supernovae explosions. In recent years, substantial progress has been made in elucidating the nature of this process in confined systems with walls, obstacles, etc. It remains unclear, however, whether a subsonic turbulent flame in an unconfined environment can undergo a DDT. We present simulations of premixed flames in stoichiometric H2-air and CH4-air mixtures interacting with high-intensity turbulence. These calculations demonstrate the DDT in unconfined systems unassisted by shocks or obstacles. We discuss the mechanism of this process and its implications.

  5. Introduction to Physics and Chemistry of Combustion Explosion, Flame, Detonation

    CERN Document Server

    Liberman, Michael A

    2008-01-01

    Most of the material covered in this book deals with the fundamentals of chemistry and physics of key processes and fundamental mechanisms for various combustion and combustion related phenomena in gaseous combustible mixture. It provides the reader with basic knowledge of burning processes and mechanisms of reaction wave propagation. The combustion of a gas mixture (flame, explosion, detonation) is necessarily accompanied by motion of the gas. The process of combustion is therefore not only a chemical phenomenon but also one of gas dynamics. The material selection focuses on the gas phase and

  6. Effects of hypothetical improvised nuclear detonation on the electrical infrastructure

    International Nuclear Information System (INIS)

    We study the impacts of a hypothetical improvised nuclear detonation (IND) on the electrical infrastructure and its cascading effects on other urban inter-dependent infrastructures of a major metropolitan area in the US. We synthesize open source information, expert knowledge, commercial software and Google Earth data to derive a realistic electrical transmission and distribution network spanning the region. A dynamic analysis of the geo-located grid is carried out to determine the cause of malfunction of components, and their short-term and long-term effect on the stability of the grid. Finally a detailed estimate of the cost of damage to the major components of the infrastructure is provided.

  7. Circumstellar absorption in double detonation Type Ia supernovae

    OpenAIRE

    Shen, Ken J.; Guillochon, James; Foley, Ryan J.

    2013-01-01

    Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He+C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O wh...

  8. Detonation Initiation by Annular Jets and Shock Waves

    OpenAIRE

    Shepherd, Joseph E.

    2005-01-01

    The objective of this research is to experimentally determine the feasibility of initiating detonation in fuel-air mixtures using only the energy in hot, compressed air. The existing 6-inch shock tube at Caltech was used to create hot, high-pressure air behind a reflected shock wave. The hot air created an imploding annular shock wave when it jetted through an annular orifice into a 76-mm-diameter, 1-m-long tube attached to the end of the shock tube. A special test section with an annular ...

  9. 30 CFR 75.1312 - Explosives and detonators in underground magazines.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Explosives and detonators in underground... LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1312 Explosives and detonators in underground magazines. (a) The quantity of explosives...

  10. Numerical study of detonation wave propagation in a confined supersonic flow

    Science.gov (United States)

    Yi, T. H.; Lu, F. K.; Wilson, D. R.; Emanuel, G.

    2016-07-01

    The dynamics of detonation waves propagating in a confined supersonic flow is numerically investigated to understand the effects of incoming flow velocity in a combustion chamber on detonation properties and structure. The computational code is based on the Euler equations with detailed chemistry. The detonation is directly initiated with high pressure and temperature at a given region inside a straight tube and then propagates both upstream and downstream. The study shows that as the incoming flow velocity increases, the properties of the detonation wave moving upstream and downstream are significantly changed. This leads to an increase or decrease in the velocity and strength of the detonation wave, and a change in smoked foil cellular pattern. It was found that the strength of the upstream-moving detonation becomes higher and the propagation velocity decreases as the incoming velocity increases. These factors result in a change of the smoked foil pattern such as the cell length, width, and track angle. Moreover, the time in stabilizing the detonations moving in opposite directions is significantly changed with a supersonic incoming flow. An initiation delay occurs on the downstream-moving detonation since it is weakened in a supersonic flow.

  11. Effect of the initial pressure of multicomponent bubble media on the characteristics of detonation waves

    Science.gov (United States)

    Sychev, A. I.

    2016-05-01

    The effect of the initial pressure of multicomponent bubble media on the conditions of initiation, the structure, the velocity, and the pressure of detonation waves is experimentally studied. The variation of the initial pressure of a bubble medium is found to be an effective method to control the parameters of bubble detonation waves.

  12. The Los Alamos detonating pellet test (DPT): PBX 9501 evaluation tests

    International Nuclear Information System (INIS)

    High explosive (HE) Velocity of Detonation (VOD) measurements are usually conducted using rate-stick-type tests. This method is highly accurate if carefully implemented, but is relatively costly and may require kilograms or more of HE depending on its sensitivity. We present a novel technique for inferring VOD using a single HE pellet, which for Conventional High Explosives (CHEs) can use 10 gm of HE or even less. This attribute makes the Detonating Pellet Test (DPT) ideal for the preliminary performance characterization of newly synthesized HE materials. On the other end of the size spectrum, the DPT can be scaled to very large dimensions so as to minimize the HE load necessary to characterize highly insensitive HEs such as ANFO. The DPT exploits the fact that the detonation emerging from the pellet face can be made highly spherical over some central region. Spherical detonation breakout on the Sample Pellet (SP) face is described by a simple analytic equation, which depends on the VOD and the Center Of Initiation (COI). The latter is determined by separate characterization of the detonator, with a wave refraction correction at the detonator/SP interface. The SP VOD is then determined by fitting the ideal breakout equation, with specified detonator COI, to detonation breakout data obtained via streak camera. We develop the DPT method and appraise it using sample PBX 9501 data in particular, while discussing its benefits and limitations in general.

  13. THE EFFECTS OF CURVATURE AND EXPANSION ON HELIUM DETONATIONS ON WHITE DWARF SURFACES

    International Nuclear Information System (INIS)

    Accreted helium layers on white dwarfs have been highlighted for many decades as a possible site for a detonation triggered by a thermonuclear runaway. In this paper, we find the minimum helium layer thickness that will sustain a steady laterally propagating detonation and show that it depends on the density and composition of the helium layer, specifically 12C and 16O. Detonations in these thin helium layers have speeds slower than the Chapman-Jouget (CJ) speed from complete helium burning, vCJ = 1.5 × 109 cm s–1. Though gravitationally unbound, the ashes still have unburned helium (≈80% in the thinnest cases) and only reach up to heavy elements such as 40Ca, 44Ti, 48Cr, and 52Fe. It is rare for these thin shells to generate large amounts of 56Ni. We also find a new set of solutions that can propagate in even thinner helium layers when 16O is present at a minimum mass fraction of ≈0.07. Driven by energy release from α captures on 16O and subsequent elements, these slow detonations only create ashes up to 28Si in the outer detonated He shell. We close by discussing how the unbound helium burning ashes may create faint and fast 'Ia' supernovae as well as events with virtually no radioactivity, and speculate on how the slower helium detonation velocities impact the off-center ignition of a carbon detonation that could cause a Type Ia supernova in the double detonation scenario

  14. Heat flows to the combustion chamber walls in detonation and turbulent combustion regimes

    Science.gov (United States)

    Bykovskii, F. A.

    1991-02-01

    Measuremens of heat flows to the walls of an annular combustion chamber under conditions of combustion and continuous detonation are reported for a propane-oxygen mixture. It is shown that specific heat flows to the chamber walls under conditions of detonation are significantly lower than those observed during ordinary combustion. The experimental equipment and details of the experimental procedure are described.

  15. The Los Alamos detonating pellet test (DPT): PBX 9501 evaluation tests

    Science.gov (United States)

    Preston, D. N.; Hill, L. G.; Tappan, B. C.

    2014-05-01

    High explosive (HE) Velocity of Detonation (VOD) measurements are usually conducted using rate-stick-type tests. This method is highly accurate if carefully implemented, but is relatively costly and may require kilograms or more of HE depending on its sensitivity. We present a novel technique for inferring VOD using a single HE pellet, which for Conventional High Explosives (CHEs) can use 10 gm of HE or even less. This attribute makes the Detonating Pellet Test (DPT) ideal for the preliminary performance characterization of newly synthesized HE materials. On the other end of the size spectrum, the DPT can be scaled to very large dimensions so as to minimize the HE load necessary to characterize highly insensitive HEs such as ANFO. The DPT exploits the fact that the detonation emerging from the pellet face can be made highly spherical over some central region. Spherical detonation breakout on the Sample Pellet (SP) face is described by a simple analytic equation, which depends on the VOD and the Center Of Initiation (COI). The latter is determined by separate characterization of the detonator, with a wave refraction correction at the detonator/SP interface. The SP VOD is then determined by fitting the ideal breakout equation, with specified detonator COI, to detonation breakout data obtained via streak camera. We develop the DPT method and appraise it using sample PBX 9501 data in particular, while discussing its benefits and limitations in general.

  16. Characterization of Detonation Soot Produced During Steady and Overdriven Conditions for Three High Explosive Formulations

    Science.gov (United States)

    Podlesak, David; Amato, Ronald; Dattelbaum, Dana; Firestone, Millicent; Gustavsen, Richard; Huber, Rachel; Ringstrand, Bryan

    2015-06-01

    The detonation of high explosives (HE) produces a dense fluid of molecular gases and solid carbon. The solid detonation carbon contains various carbon allotropes such as detonation nanodiamonds, ``onion-like'' carbon, graphite and amorphous carbon, with the formation of the different forms dependent upon pressure, temperature and the environmental conditions of the detonation. We have collected solid carbon residues from controlled detonations of three HE formulations (Composition B-3, PBX 9501, and PBX 9502). Soot was collected from experiments designed to produce both steady and overdriven conditions, and from detonations in both an ambient (air) atmosphere and in an inert Ar atmosphere. Structural studies to glean the features of the solid carbon products have been performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Raman spectroscopy, small-angle X-ray scattering (SAXS), and X-Ray Pair Distribution Function measurements (PDF). Bulk soot was also analyzed for elemental and isotopic compositions. We will discuss differences in the structure and composition of the detonation carbon as a function of formulation, detonation conditions, and the surrounding atmosphere.

  17. Impact of Dissociation and Sensible Heat Release on Pulse Detonation and Gas Turbine Engine Performance

    Science.gov (United States)

    Povinelli, Louis A.

    2001-01-01

    A thermodynamic cycle analysis of the effect of sensible heat release on the relative performance of pulse detonation and gas turbine engines is presented. Dissociation losses in the PDE (Pulse Detonation Engine) are found to cause a substantial decrease in engine performance parameters.

  18. Modeling Detonation of Heterogeneous Explosives with Embedded Inert Particles Using Detonation Shock Dynamics: Normal and Divergent Propagation in Regular and Simplified Microstructure

    Science.gov (United States)

    Stewart, Scott

    2012-11-01

    We use a detonation shock propagation model, Detonation Shock Dynamics (DSD) to compute the interaction of a detonation shock wave that passes over a series of inert spherical particles embedded in a high explosive material. DSD provides an efficient means to study the dynamics of lead shock waves without the necessity of simulating the entire multi-material, reactive flow field. We derive partial differential equations for the motion of a detonation shock that obeys a linear shock normal velocity-curvature relation in a cylindrical coordinate system and in a moving, shock-attached coordinate system. The shock dynamics equations are solved numerically, in a unit-cell configuration. We describe the short-term and long-term behavior of the shock wave as it passes over the particles. We describe both the averages and character of the stochastic behavior that affects long-term average properties for microstructure in which the inert particles are periodically and randomly spaced.

  19. Head-on Collision of a Detonation with a Planar Shock Wave

    Science.gov (United States)

    Ng, H. D.; Botros, B. B.; Chao, J.; Yang, J. M.; Nikiforakis, N.; Lee, J. H. S.

    2006-09-01

    The phenomenon that occurs when a Chapman Jouguet (CJ) detonation collides with a shock wave is discussed. Assuming a one-dimensional steady wave configuration analogous to a planar shock shock frontal interaction, analytical solutions of the Rankine Hugoniot relationships for the transmitted detonation and the transmitted shock are obtained by matching the pressure and particle velocity at the contact surface. The analytical results indicate that there exist three possible regions of solutions, i.e. the transmitted detonation can have either strong, weak or CJ solution, depending on the incident detonation and shock strengths. On the other hand, if we impose the transmitted detonation to have a CJ solution followed by a rarefaction fan, the boundary conditions are also satisfied at the contact surface. The existence of these multiple solutions is verified by an experimental investigation. It is found that the experimental results agree well with those predicted by the second wave interaction model and that the transmitted detonation is a CJ detonation. Unsteady numerical simulations of the reactive Euler equations with both simple one-step Arrhenius kinetic and chain-branching kinetic models are also carried out to look at the transient phenomena and at the influence of a finite reaction thickness of a detonation wave on the problem of head-on collision with a shock. From all the computational results, a relaxation process consisting of a quasi-steady period and an overshoot for the transmitted detonation subsequent to the head-on collisions can be observed, followed by the asymptotic decay to a CJ detonation as predicted theoretically. For unstable pulsating detonations, it is found that, due to the increase in the thermodynamic state of the reactive mixture caused by the shock, the transmitted pulsating detonation can become more stable with smaller amplitude and period oscillation. These observations are in good agreement with experimental evidence obtained

  20. Numerical investigation on detonation cell evolution in a channel with area-changing cross section

    Institute of Scientific and Technical Information of China (English)

    DENG; Bo

    2007-01-01

    The two-dimensional cellular detonation propagating in a channel with area- changing cross section was numerically simulated with the dispersion-controlled dissipative scheme and a detailed chemical reaction model. Effects of the flow expansion and compression on the cellular detonation cell were investigated to illustrate the mechanism of the transverse wave development and the cellular detonation cell evolution. By examining gas composition variations behind the leading shock, the chemical reaction rate, the reaction zone length, and thermodynamic parameters, two kinds of the abnormal detonation waves were identified. To explore their development mechanism, chemical reactions, reflected shocks and rarefaction waves were discussed, which interact with each other and affect the cellular detonation in different ways.  ……