WorldWideScience

Sample records for spiral corrugated culvert

  1. Swimming behaviour and ascent paths of brook trout in a corrugated culvert

    Science.gov (United States)

    Goerig, Elsa; Bergeron, Normand E.; Castro-Santos, Theodore R.

    2017-01-01

    Culverts may restrict fish movements under some hydraulic conditions such as shallow flow depths or high velocities. Although swimming capacity imposes limits to passage performance, behaviour also plays an important role in the ability of fish to overcome velocity barriers. Corrugated metal culverts are characterized by unsteady flow and existence of low‐velocity zones, which can improve passage success. Here, we describe swimming behaviour and ascent paths of 148 wild brook trout in a 1.5‐m section of a corrugated metal culvert located in Raquette Stream, Québec, Canada. Five passage trials were conducted in mid‐August, corresponding to specific mean cross‐sectional flow velocities ranging from 0.30 to 0.63 m/s. Fish were individually introduced to the culvert and their movements recorded with a camera located above the water. Lateral and longitudinal positions were recorded at a rate of 3 Hz in order to identify ascent paths. These positions were related to the distribution of flow depths and velocities in the culvert. Brook trout selected flow velocities from 0.2 to 0.5 m/s during their ascents, which corresponded to the available flow velocities in the culvert at the low‐flow conditions. This however resulted in the use of low‐velocity zones at higher flows, mainly located along the walls of the culvert. Some fish also used the corrugations for sheltering, although the behaviour was marginal and did not occur at the highest flow condition. This study improves knowledge on fish behaviour during culvert ascents, which is an important aspect for developing reliable and accurate estimates of fish passage ability.

  2. Corrosion of Spiral Rib Aluminized Pipe : [Summary

    Science.gov (United States)

    2012-01-01

    Large diameter, corrugated steel pipes are a common sight in the culverts that run alongside many Florida roads. Spiral-ribbed aluminized pipe (SRAP) has been widely specified by the Florida Department of Transportation (FDOT) for runoff drainage. Th...

  3. Corrosion of Spiral Rib Aluminized Pipe

    Science.gov (United States)

    2012-08-01

    Large diameter, corrugated steel pipes are a common sight in the culverts that run alongside many Florida roads. Spiral-ribbed aluminized pipe (SRAP) has been widely specified by the Florida Department of Transportation (FDOT) for runoff drainage. Th...

  4. On the Fully-Developed Heat Transfer Enhancing Flow Field in Sinusoidally, Spirally Corrugated Tubes Using Computational Fluid Dynamics

    DEFF Research Database (Denmark)

    Hærvig, Jakob; Sørensen, Kim; Condra, Thomas Joseph

    2017-01-01

    A numerical study has been carried out to investigate heat transfer enhancing flow field in 28 geometrically different sinusoidally, spirally corrugated tubes. To vary the corrugation, the height of corrugation e/D and the length between two successive corrugated sections p/D are varied in the ra...

  5. Pressure drop and stability of flow in Archimedean spiral tube with transverse corrugations

    Directory of Open Access Journals (Sweden)

    Đorđević Milan

    2016-01-01

    Full Text Available Isothermal pressure drop experiments were carried out for the steady Newtonian fluid flow in Archimedean spiral tube with transverse corrugations. Pressure drop correlations and stability criteria for distinguishing the flow regimes have been obtained in a continuous Reynolds number range from 150 to 15 000. The characterizing geometrical groups which take into account all the geometrical parameters of Archimedean spiral and corrugated pipe has been acquired. Before performing experiments over the Archimedean spiral, the corrugated straight pipe having high relative roughness e/d = 0.129 of approximately sinusoidal type was tested in order to obtain correlations for the Darcy friction factor. Insight into the magnitude of pressure loss in the proposed geometry of spiral solar receiver for different flow rates is important because of its effect upon the efficiency of the receiver. Although flow in spiral and corrugated geometries has the advantages of compactness and high heat transfer rates, the disadvantage of greater pressure drops makes hydrodynamic studies relevant. [Projekat Ministarstva nauke Republike Srbije, br. III 42006 i br. TR 33015

  6. Numerical Investigation of the Fully-Developed Periodic Flow Field for Optimal Heat Transfer in Spirally Corrugated Tubes

    DEFF Research Database (Denmark)

    Hærvig, Jakob; Condra, Thomas Joseph; Sørensen, Kim

    Even though the corrugated tube is a widely used technique to enhance transfer heat, the exact heat transfer enhancing mechanism remains relatively un-documented. Most studies attribute the favourable heat transfer characteristics to a swirling flow being present at higher corrugation....... In this study, a systematic approach relying on Computational Fluid Dynamics (CFD) is used to study and compare the heat transfer characteristics with the detailed flow field in the spirally corrugated tubes. By comparing the flow in 12 different spirally corrugated tubes at a fixed Reynolds number of 5000......, this study compares the flow field with the surface averaged Nusselt number to gain valuable insight into which flow phenomena causes favourable heat transfer characteristics. While the flow at low corrugations approximates the non-corrugated tube, higher corrugations of h/D creates a significant tangential...

  7. EXPERIMENTAL INVESTIGATION OF THE CONVECTIVE HEAT TRANSFER IN A SPIRALLY COILED CORRUGATED TUBE WITH RADIANT HEATING

    Directory of Open Access Journals (Sweden)

    Milan Đorđević

    2017-12-01

    Full Text Available The Archimedean spiral coil made of a transversely corrugated tube was exposed to radiant heating in order to represent a heat absorber of the parabolic dish solar concentrator. The main advantage of the considered innovative design solution is a coupling effect of the two passive methods for heat transfer enhancement - coiling of the flow channel and changes in surface roughness. The curvature ratio of the spiral coil varies from 0.029 to 0.234, while water and a mixture of propylene glycol and water are used as heat transfer fluids. The unique focus of this study is on specific boundary conditions since the heat flux upon the tube external surfaces varies not only in the circumferential direction, but in the axial direction as well. Instrumentation of the laboratory model of the heat absorber mounted in the radiation field includes measurement of inlet fluid flow rate, pressure drop, inlet and outlet fluid temperature and 35 type K thermocouples welded to the coil surface. A thermal analysis of the experimentally obtained data implies taking into consideration the externally applied radiation field, convective and radiative heat losses, conduction through the tube wall and convection to the internal fluid. The experimental results have shown significant enhancement of the heat transfer rate compared to spirally coiled smooth tubes, up to 240% in the turbulent flow regime.

  8. VTrans Small Culvert Inventory - Culverts

    Data.gov (United States)

    Vermont Center for Geographic Information — Vermont Agency of Transportation Small Culvert Inventory: Culverts. This data contains small culverts locations along VTrans maintained roadways. The data was...

  9. Heat transfer and pressure drop studies of TiO2/DI water nanofluids in helically corrugated tubes using spiraled rod inserts

    Science.gov (United States)

    Anbu, S.; Venkatachalapathy, S.; Suresh, S.

    2018-05-01

    An experimental study on the convective heat transfer and friction factor characteristics of TiO2/DI water nanofluids in uniformly heated plain and helically corrugated tubes (HCT) with and without spiraled rod inserts (SRI) under laminar flow regime is presented in this paper. TiO2 nanoparticles with an average size of 32 nm are dispersed in deionized (DI) water to form stable suspensions containing 0.1, 0.15, 0.2, and 0.25% volume concentrations of nanoparticles. It is found that the inclusion of nanoparticles to DI water ameliorated Nusselt number which increased with nanoparticles concentration upto 0.2%. Two spiraled rod inserts made of copper with different pitches (pi = 50 mm and 30 mm) are inserted in both plain and corrugated tubes and it is found that the addition of these inserts increased the Nusselt number substantially. For Helically corrugated tube with lower pitch and maximum height of corrugation (pc = 8 mm, hc = 1 mm) with 0.2% volume concentration of nanoparticles, a maximum enhancement of 15% in Nusselt number is found without insert and with insert having lower pitch (pi = 30 mm) the enhancement is 34% when compared to DI water in plain tube. The results on friction factor show a maximum penalty of about 53.56% for the above HCT.

  10. Brook trout passage performance through culverts

    Science.gov (United States)

    Goerig, Elsa; Castro-Santos, Theodore R.; Bergeron, Normand

    2016-01-01

    Culverts can restrict access to habitat for stream-dwelling fishes. We used passive integrated transponder telemetry to quantify passage performance of >1000 wild brook trout (Salvelinus fontinalis) attempting to pass 13 culverts in Quebec under a range of hydraulic and environmental conditions. Several variables influenced passage success, including complex interactions between physiology and behavior, hydraulics, and structural characteristics. The probability of successful passage was greater through corrugated metal culverts than through smooth ones, particularly among smaller fish. Trout were also more likely to pass at warmer temperatures, but this effect diminished above 15 °C. Passage was impeded at higher flows, through culverts with steep slopes, and those with deep downstream pools. This study provides insight on factors influencing brook trout capacity to pass culverts as well as a model to estimate passage success under various conditions, with an improved resolution and accuracy over existing approaches. It also presents methods that could be used to investigate passage success of other species, with implications for connectivity of the riverscape.

  11. Radiant absorption characteristics of corrugated curved tubes

    Directory of Open Access Journals (Sweden)

    Đorđević Milan Lj.

    2017-01-01

    Full Text Available The utilization of modern paraboloidal concentrators for conversion of solar radiation into heat energy requires the development and implementation of compact and efficient heat absorbers. Accurate estimation of geometry influence on absorption characteristics of receiver tubes is an important step in this process. This paper deals with absorption characteristics of heat absorber made of spirally coiled tubes with transverse circular corrugations. Detailed 3-D surface-to-surface Hemicube method was applied to compare radiation performances of corrugated and smooth curved tubes. The numerical results were obtained by varying the tube curvature ratio and incident radiant heat flux intensity. The details of absorption efficiency of corrugated tubes and the effect of curvature on absorption properties for both corrugated and smooth tubes were presented. The results may have significance to further analysis of highly efficient heat absorbers exposed to concentrated radiant heating. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 42006

  12. Computation of peak discharge at culverts

    Science.gov (United States)

    Carter, Rolland William

    1957-01-01

    Methods for computing peak flood flow through culverts on the basis of a field survey of highwater marks and culvert geometry are presented. These methods are derived from investigations of culvert flow as reported in the literature and on extensive laboratory studies of culvert flow. For convenience in computation, culvert flow has been classified into six types, according to the location of the control section and the relative heights of the head-water and tail-water levels. The type of flow which occurred at any site can be determined from the field data and the criteria given in this report. A discharge equation has been developed for each flow type by combining the energy and continuity equations for the distance between an approach section upstream from the culvert and a terminal section within the culvert barrel. The discharge coefficient applicable to each flow type is listed for the more common entrance geometries. Procedures for computing peak discharge through culverts are outlined in detail for each of the six flow types.

  13. Culvert Length and Interior Lighting Impacts to Topeka Shiner Passage

    Science.gov (United States)

    2017-11-01

    Culverts can act as barriers to fish passage for a number of reasons including insufficient water depth or excess velocity. In addition, concern is being raised over behavioral barriers where culvert conditions elicit an avoidance response that deter...

  14. Anatomy of the Corrugator Muscle.

    Science.gov (United States)

    Hwang, Kun; Lee, Jung Hun; Lim, Hee Joong

    2017-03-01

    The aim of this article is to systematically review the anatomy and action of the corrugator muscle. PubMed and Scopus were searched using the terms "corrugator" AND "anatomy." Among the 60 full texts from the 145 relevant abstracts, 34 articles without sufficient content were excluded and 4 articles drawn from the reference lists were added. Among the 30 articles analyzed (721 hemifaces), 28% classified by oblique head and transverse head, and 72% did not. Corrugator originated mostly from the medial supraorbital rim (45%), followed by the medial frontal bone (31%), the medial infraorbital rim (17%), and the upper nasal process (7%). Corrugator extended through the frontalis and orbicularis oculi (41%), only the frontalis (41%), or only the orbicularis oculi (18%). Corrugator ran superolaterally (59%), or laterally (41%). Corrugators inserted mostly to the middle of the eyebrow (57%), or the medial half of the eyebrow (36%), but also to the glabella region (7%). The length of the corrugator ranged 38 to 53 mm. The transverse head (23.38 mm) was longer than the oblique head (19.75 mm). Corrugator was thicker at the medial canthus than at the midpupillary line. Corrugator was innervated by the temporal branch of the facial nerve (66%), the zygomatic branch (17%), or the angular nerve (zygomatic branch and buccal branch, 17%). Supraorbital nerve (60%) or supratrochlear nerve (40%) penetrated the corrugator. The action was depressing, pulling the eyebrow medially (91%), or with medial eyebrow elevation and lateral eyebrow depression (9%). Surgeons must keep this anatomy in mind during surgical procedures.

  15. Road Bridges and Culverts, MDTA Culverts, Culverts on John F. Kennedy Highway (I95), Baltimore Harbor Tunnel Throughway, Francis Scott Key Bridge, Bay bridge, Nice Bridge, Published in 2010, 1:1200 (1in=100ft) scale, Maryland Transportation Authority.

    Data.gov (United States)

    NSGIC State | GIS Inventory — Road Bridges and Culverts dataset current as of 2010. MDTA Culverts, Culverts on John F. Kennedy Highway (I95), Baltimore Harbor Tunnel Throughway, Francis Scott Key...

  16. Logarithmic Spiral

    Indian Academy of Sciences (India)

    Switzerland) even today can see the. Archimedian spiral and the inscription under it on the tombstone of Jacob Bernoulli 1. Logarithmic Spiral in Nature. Apart from logarithmic spiral no other curve seems to have attracted the attention of scientists, ...

  17. Experimental studies of Steel Corrugated Constructions

    Directory of Open Access Journals (Sweden)

    Lazarev Yuriy

    2016-01-01

    Full Text Available The purpose of this particular article is to assess existing calculations of steel corrugated constructions. Steel Corrugated Construction is a perspective type of constructions, which is exhibiting numerous advantages in comparison with one that currently applied in automobile and railroad networks (reinforced concrete water-throughput pipes, reinforced concrete frame bridges. The evaluation of experimental data on models of constructions of this particular type has been carried out in order to improve calculations of Steel Corrugated Constructions.

  18. Spiral symmetry

    CERN Document Server

    Hargittai, Istvan

    1992-01-01

    From the tiny twisted biological molecules to the gargantuan curling arms of many galaxies, the physical world contains a startling repetition of spiral patterns. Today, researchers have a keen interest in identifying, measuring, and defining these patterns in scientific terms. Spirals play an important role in the growth processes of many biological forms and organisms. Also, through time, humans have imitated spiral motifs in their art forms, and invented new and unusual spirals which have no counterparts in the natural world. Therefore, one goal of this multiauthored book is to stress the c

  19. Culvert information management system : demonstration project, final report, August 2009.

    Science.gov (United States)

    2009-08-01

    The overall objective of the research was to develop a pilot scale Culvert Information Management System (CIMS) that will : comply with both requirements stipulated by the Governmental Accounting Standards Board (GASB-34) and new federal : storm wate...

  20. Nonlinear finite element modeling of corrugated board

    Science.gov (United States)

    A. C. Gilchrist; J. C. Suhling; T. J. Urbanik

    1999-01-01

    In this research, an investigation on the mechanical behavior of corrugated board has been performed using finite element analysis. Numerical finite element models for corrugated board geometries have been created and executed. Both geometric (large deformation) and material nonlinearities were included in the models. The analyses were performed using the commercial...

  1. Flow induced pulsations caused by corrugated tubes

    NARCIS (Netherlands)

    Shatto, D.P.; Belfroid, S.P.C.; Peters, M.C.A.M.

    2007-01-01

    Corrugated tubes can produce a tonal noise when used for gas transport, for instance in the case of flexible risers. The whistling sound is generated by shear layer instability due to the boundary layer separation at each corrugation. This whistling is examined by investigating the frequency,

  2. Flow induced pulsations generated in corrugated tubes

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Swindell, R.; Tummers, R.

    2008-01-01

    Corrugated tubes can produce a tonal noise when used for gas transport, for instance in the case of flexible risers. The whistling sound is generated by shear layer instability due to the boundary layer separation at each corrugation. This whistling is examined by investigating the frequency,

  3. Corrugated megathrust revealed offshore from Costa Rica

    Science.gov (United States)

    Edwards, Joel H.; Kluesner, Jared; Silver, Eli A.; Brodsky, Emily E.; Brothers, Daniel; Bangs, Nathan L.; Kirkpatrick, James D.; Wood, Ruby; Okamato, Kristina

    2018-01-01

    Exhumed faults are rough, often exhibiting topographic corrugations oriented in the direction of slip; such features are fundamental to mechanical processes that drive earthquakes and fault evolution. However, our understanding of corrugation genesis remains limited due to a lack of in situ observations at depth, especially at subducting plate boundaries. Here we present three-dimensional seismic reflection data of the Costa Rica subduction zone that image a shallow megathrust fault characterized by corrugated, and chaotic and weakly corrugated topographies. The corrugated surfaces extend from near the trench to several kilometres down-dip, exhibit high reflection amplitudes (consistent with high fluid content/pressure) and trend 11–18° oblique to subduction, suggesting 15 to 25 mm yr−1 of trench-parallel slip partitioning across the plate boundary. The corrugations form along portions of the megathrust with greater cumulative slip and may act as fluid conduits. In contrast, weakly corrugated areas occur adjacent to active plate bending faults where the megathrust has migrated up-section, forming a nascent fault surface. The variations in megathrust roughness imaged here suggest that abandonment and then reestablishment of the megathrust up-section transiently increases fault roughness. Analogous corrugations may exist along significant portions of subduction megathrusts globally.

  4. Electromagnetic radiation of electrons in corrugated graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ktitorov, S. A., E-mail: ktitorov@mail.ioffe.ru; Myhamadiarov, R. I. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2016-08-15

    Bremsstrahlung in corrugated single-layer graphene in the presence of a ballistic transport current is analyzed. Radiation of a similar nature is observed in undulators and wigglers. Regular and chaotic corrugations (ripples) are considered. It is shown that the quadratic relation between the Monge membrane function and the synthetic calibration field leads to the appearance of a central peak in the radiation spectral density. Possible formation mechanisms of single-layer graphene corrugation are proposed. In one case, the corrugation is considered as an incommensurate superstructure in a two-dimensional crystal, resulting from instability developing in the optical phonon subsystem with the formation of a periodic soliton train. Corrugation results from the interaction of subsystems. Another possible mechanism consists in instability of the membrane flat state due to strong fluctuations characteristic of two-dimensional systems.

  5. Frequency spirals

    International Nuclear Information System (INIS)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.

    2016-01-01

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call “frequency spirals.” These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  6. Frequency spirals

    Energy Technology Data Exchange (ETDEWEB)

    Ottino-Löffler, Bertrand; Strogatz, Steven H., E-mail: strogatz@cornell.edu [Center for Applied Mathematics, Cornell University, Ithaca, New York 14853 (United States)

    2016-09-15

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call “frequency spirals.” These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  7. Water quality implications of culvert repair options : cementitious and polyurea spray-on liners.

    Science.gov (United States)

    2012-11-01

    Many commonly used culvert rehabilitation technologies entail the use of a resin or coating that cures to form a rigid : liner within the damaged culvert. However, the potential environmental impacts of leaching or release of contaminants during : no...

  8. Longitudinal habitat disruption in Neotropical streams: fish assemblages under the influence of culverts

    Directory of Open Access Journals (Sweden)

    José Roberto Mariano

    Full Text Available This study assessed differences in fish assemblages existing upstream and downstream two types of culverts, one on each of two different Neotropical streams. We analyzed the composition and structure of the ichthyofauna and tested for spatial patterns. Fish sampling was carried out monthly between November 2009 and October 2010 using different fishing gears. We collected 2,220 fish of 33 species; 901 in stretches of the Lopeí stream - circular culvert and 1,310 in stretches of the Pindorama stream - box culvert. Fish abundance was similar in upstream and downstream stretches of the circular culvert, whereas it was slightly higher in the upstream than downstream stretch for the box culvert. Characiformes predominated in the upstream stretch of both culverts. On the other hand, Siluriformes was abundant in the downstream stretch of the circular culvert, with similar abundance in the stretches of the box culvert. Species richness and diversity (Shannon-Weiner Index were higher in the downstream stretch of the circular culvert, but they were similar in both stretches of the box culvert. The most abundant species were Astyanax altiparanae, A. paranae, A. fasciatus, Ancistrus sp., and Hypostomus sp. The last two species were more abundant in the downstream stretch of the circular culvert, and similar in stretches of the box culvert. Our study indicated variations in the species abundance, richness, and diversity between upstream and downstream stretches in particular of the circular culvert in the Lopeí stream, suggesting that fish movements are restrained more intensively in this culvert, especially for Siluriformes. The drop in the circular culvert outlet probably created passage barriers especially for those fish that has no ability to jump, where downstream erosion could lead to culvert perching. Studies on appropriate road crossing design or installation are fundamental whereas improvements in these structures can restore the connectivity of

  9. Corrugated Membrane Nonlinear Deformation Process Calculation

    OpenAIRE

    A. S. Nikolaeva; S. A. Podkopaev

    2015-01-01

    Elastic elements are widely used in instrumentation. They are used to create a particular interference between the parts, for accumulating mechanical energy, as the motion transmission elements, elastic supports, and sensing elements of measuring devices. Device reliability and quality depend on the calculation accuracy of the elastic elements. A corrugated membrane is rather common embodiment of the elastic element.The corrugated membrane properties depend largely on its profile i.e. a gener...

  10. Is motivation important to brook trout passage through culverts?

    Science.gov (United States)

    Goerig, Elsa; Castro-Santos, Theodore R.

    2017-01-01

    Culverts can restrict movement of stream-dwelling fish. Motivation to enter and ascend these structures is an essential precursor for successful passage. However, motivation is challenging to quantify. Here, we use attempt rate to assess motivation of 447 brook trout (Salvelinus fontinalis) entering three culverts under a range of hydraulic, environmental, and biological conditions. A passive integrated transponder system allowed for the identification of passage attempts and success of individual fish. Attempt rate was quantified using time-to-event analysis allowing for time-varying covariates and recurrent events. Attempt rate was greatest during the spawning period, at elevated discharge, at dusk, and for longer fish. It decreased during the day and with increasing number of conspecifics downstream of the culvert. Results also show a positive correlation between elevated motivation and successful passage. This study enhances understanding of factors influencing brook trout motivation to ascend culverts and shows that attempt rate is a dynamic phenomenon, variable over time and among individuals. It also presents methods that could be used to investigate other species’ motivation to pass natural or anthropogenic barriers.

  11. Cells on corrugations for pollution control

    International Nuclear Information System (INIS)

    Clyde, R.

    1993-01-01

    Old cardboard boxes constitute 12% of landfills. White rot fungus can be grown on the boxes and buried in contaminated soil. The fungus needs air which is entrapped in the corrugations. The fungus is sensitive to large amounts of TNT but it is protected when inside the corrugations. Fast food containers are filling landfills. Lactic acid production needs air and the polymers are biodegradable. When corrugations are put in a half full rotary unit, holes in the valleys make drops, and mass transfer to drops is much higher than to a flat surface. A lab corrugator has been made from an old washing machine wringer, so other fibers can be corrugated. When the bacterium, Zymomonas mobilis is grown on Tyvek fiber, lead and six valent chromium are removed from wastewater in a few seconds. Zymomonas on rotating fibers converts sugar to alcohol in 10--15 minutes and when a light is shown into flat rotating discs, it hits a thin moving film to destroy dioxin. Salt on roads causes millions of dollars damage to bridges and cars but calcium magnesium acetate is not corrosive and can be made with cells on rotating fibers

  12. Turtles and culverts, and alternative energy development: an unreported but potentially significant mortality threat to the desert tortoise (Gopherus agassizii)

    Science.gov (United States)

    Lovich, J.E.; Ennen, J.R.; Madrak, S.; Grover, B.

    2011-01-01

    Culverts are often used to increase the permeability of roaded landscapes for wildlife, including turtles. Although the benefits of culverts as safe passages for turtles are well documented, under some conditions culverts can entrap them and cause mortality. Here we report a culvert-related mortality in the federally threatened desert tortoise (Gopherus agassizii) at a wind energy facility in California and offer simple recommendations to mitigate the negative effects of culverts for wildlife in general.

  13. Assessment of rail long-pitch corrugation

    Science.gov (United States)

    Valehrach, Jan; Guziur, Petr; Riha, Tomas; Plasek, Otto

    2017-09-01

    The paper focuses on defects of the running surface of the rail, namely the rail corrugation defect and specifically long-pitch corrugation in curves of small radii. These defects cause a shorter life of the rails, greater maintenance costs and increase the noise and vibration pollution. Therefore, it is very important to understand the formation and development of the imperfection of the rails. In the paper, various sections of railway tracks in the Czech Republic are listed, each of them completed with comparison of defect development, the particular track superstructure, rolling stock, axle load, traffic load etc. Based on performed measurements, defect development has been proved as different on sections with similar (or even same) parameters. The paper assumes that a train velocity is the significant circumstance for defect development rates. Assessment of track section with under sleeper pads, which are expected to be the one of the possible ways to suppress the corrugation defect development, is included in evaluation.

  14. Culvert Analysis Program Graphical User Interface 1.0--A preprocessing and postprocessing tool for estimating flow through culvert

    Science.gov (United States)

    Bradley, D. Nathan

    2013-01-01

    The peak discharge of a flood can be estimated from the elevation of high-water marks near the inlet and outlet of a culvert after the flood has occurred. This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks on trees or buildings. When combined with the cross-sectional geometry of the channel upstream from the culvert and the culvert size, shape, roughness, and orientation, the high-water marks define a water-surface profile that can be used to estimate the peak discharge by using the methods described by Bodhaine (1968). This type of measurement is in contrast to a “direct” measurement of discharge made during the flood where cross-sectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a streamgage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the high-flow section of the stage-discharge relation (rating curve) at the streamgage, resulting in more accurate computation of high flows. The Culvert Analysis Program (CAP) (Fulford, 1998) is a command-line program written in Fortran for computing peak discharges and culvert rating surfaces or curves. CAP reads input data from a formatted text file and prints results to another formatted text file. Preparing and correctly formatting the input file may be time-consuming and prone to errors. This document describes the CAP graphical user interface (GUI)—a modern, cross-platform, menu-driven application that prepares the CAP input file, executes the program, and helps the user interpret the output

  15. Corrugated Membrane Nonlinear Deformation Process Calculation

    Directory of Open Access Journals (Sweden)

    A. S. Nikolaeva

    2015-01-01

    Full Text Available Elastic elements are widely used in instrumentation. They are used to create a particular interference between the parts, for accumulating mechanical energy, as the motion transmission elements, elastic supports, and sensing elements of measuring devices. Device reliability and quality depend on the calculation accuracy of the elastic elements. A corrugated membrane is rather common embodiment of the elastic element.The corrugated membrane properties depend largely on its profile i.e. a generatrix of the meridian surface.Unlike other types of pressure elastic members (bellows, tube spring, the elastic characteristics of which are close to linear, an elastic characteristic of the corrugated membrane (typical movement versus external load is nonlinear. Therefore, the corrugated membranes can be used to measure quantities, nonlinearly related to the pressure (e.g., aircraft air speed, its altitude, pipeline fluid or gas flow rate. Another feature of the corrugated membrane is that significant movements are possible within the elastic material state. However, a significant non-linearity of membrane characteristics leads to severe complicated calculation.This article is aimed at calculating the corrugated membrane to obtain the elastic characteristics and the deformed shape of the membrane meridian, as well as at investigating the processes of buckling. As the calculation model, a thin-walled axisymmetric shell rotation is assumed. The material properties are linearly elastic. We consider a corrugated membrane of sinusoidal profile. The membrane load is a uniform pressure.The algorithm for calculating the mathematical model of an axisymmetric corrugated membrane of constant thickness, based on the Reissner’s theory of elastic thin shells, was realized as the author's program in C language. To solve the nonlinear problem were used a method of changing the subspace of control parameters, developed by S.S., Gavriushin, and a parameter marching method

  16. The spiral

    DEFF Research Database (Denmark)

    Bibace, Roger; Kharlamov, Nikita

    2013-01-01

    ’s work with Bernard Kaplan on symbol formation is a primer on this idea. This paper examines the idea of spirality and develops the notion of dynamic coexistence that can clarify the issue of directionality of development; that is, what is the general trajectory or ground plan that development assumes...... and the environment. The idea of dynamic coexistence is developed on this foundation. In the context of Werner and Kaplan’s work, dynamic coexistence represents the syncretic nature of processes and levels of organization: they are neither innately fused nor organized. Instead, the antithesis between fusion...

  17. Optimum fiber distribution in singlewall corrugated fiberboard

    Science.gov (United States)

    Millard W. Johnson; Thomas J. Urbanik; William E. Denniston

    1979-01-01

    Determining optimum distribution of fiber through rational design of corrugated fiberboard could result in significant reductions in fiber required to meet end-use conditions, with subsequent reductions in price pressure and extension of the softwood timber supply. A theory of thin plates under large deformations is developed that is both kinematically and physically...

  18. Stability evaluation of modernized bank protections in a culvert construction

    Science.gov (United States)

    Cholewa, Mariusz; Plesiński, Karol; Kamińska, Katarzyna; Wójcik, Izabela

    2018-02-01

    The paper presents stability evaluation of the banks of the Wilga River on a chosen stretch in Koźmice Wielkie, Małopolska Province. The examined stretch included the river bed upstream from the culvert on a district road. The culvert construction, built over four decades ago, was disassembled in 2014. The former construction, two pipes that were 1.4 m in diameter, was entirely removed. The investor decided to build a new construction in the form of insitu poured reinforced concrete with a 4 x 2 m cross section. Change of geometry and different location in relation to the river current caused increase in the flow velocity and, as a consequence, erosion of both protected and natural banks. Groundwater conditions were determined based on the geotechnical tests that were carried out on soil samples taken from the banks and the river bed. Stability calculations of natural slopes of the Wilga River and the ones protected with riprap indicate mistakes in the design project concerning construction of the river banks. The purpose of the study was to determine the stability of the Wilga River banks on a selected section adjacent to the rebuilt culvert. Stability of a chosen cross section was analysed in the paper. Presented conclusions are based on the results of geotechnical tests and numerical calculations.

  19. Stiffness Matrices and Anisotropy in the Trapezoidal Corrugated Composite Sheets

    Directory of Open Access Journals (Sweden)

    Mohammad Golzar

    2013-10-01

    Full Text Available In the some applications like as morphing technology, high strain and anisotropic behavior are essential design requirements. The corrugated composite sheets due to their special geometries have potential to high deflection under axial loading through longitudinal direction of corrugation. In this research, the strain and the anisotropic behavior of corrugated composite sheets are investigated by fabricating glass/epoxy samples with trapezoidal geometries. For evaluation of the mechanical behavior of the composites the samples were subjected to tension and flexural tests in the longitudinal and transverse directions of corrugation. In order to determine anisotropic behavior of the corrugated sheets, two approaches were introduced: (1 tensile anisotropic (E* and (2 flexural anisotropic (D*. The anisotropic behavior and ultimate deflections were investigated theoretically and experimentally. In this paper, mechanical behaviors based on theoretical and experimental analysis including the elastic constants and stiffness matrices of trapezoidal corrugated composite sheets were studied and the results were verified by finite element method. The results of the numerical and analytical solutions were compared with those of experimental tests. Finally, the load-displacement curves of tensile tests in longitudinal direction of corrugation, the ultimate deflection and anisotropy behavior of these exclusive composite sheets in the corrugated composite sheets were studied experimentally. The experimental results of the trapezoidal corrugated sheets showed that one of the most important parameters in the ultimate strain was amplitude of the corrugation elements. Generally, increasing the amplitude and element per length unit of trapezoidal corrugated specimen led to higher ultimate strain.

  20. Passive heat transfer enhancement in 3D corrugated tube

    DEFF Research Database (Denmark)

    Navickaité, Kristina; Engelbrecht, Kurt; Bahl, Christian

    transfer and fluid flow with a constant wall temperature and total pressure drop. The governing equations for these problems were solved using the Finite Element Method. The results of numerical modelling show significant increase in NTU for double corrugated tubes compared to a circular tube. The friction......An innovative hydraulic design was studied for corrugated tube geometry for a heat exchanger. An ellipse based double corrugation was used as a concept of the geometry. The hydraulic diameter (Dh) is maintained over the tube length while the shape of the cross section varies continuously along...... the flow direction. 38 corrugated tubes with a Dh of 5 mm were studied numerically with corrugation heights from 0.23 to 0.69 mm and corrugation periods from 5 to 50 mm for laminar flow with water. Computational fluid dynamics (CFD) is used as a tool to study the effect of corrugation geometry on heat...

  1. Do culverts impact the movements of the endangered white-clawed crayfish?

    Directory of Open Access Journals (Sweden)

    Louca V.

    2014-01-01

    Full Text Available Culverts can impact the migration and dispersal of aquatic animals and result in population fragmentation, increasing the risk of local extinction for endangered species such as the white-clawed crayfish Austropotamobius pallipes. This study used radio telemetry and passive integrated transponder (PIT telemetry to determine whether existing and experimental covered culverts affect the upstream and downstream movements of adult white-clawed crayfish. Daily crayfish movement rates did not differ significantly between an unlit 363-m long culvert and open stream channel sections. Crayfish moved into dark, covered sections volitionally. However, limited upstream movement occurred at sudden transitions of bed height or smooth-concrete box culvert sections with fast flow, suggesting partial barrier effects. In the 20-m long experimental in-stream culvert, also dark, but with natural stream bed, 70% of radio-tagged crayfish released downstream entered the culvert, as did 60% of those released upstream. Overall 35% passed through, with similar numbers in each direction. We conclude that dark culverts up to several hundred metres do not inhibit dispersal of white-clawed crayfish, provided stream slope, bed type and water velocity are amenable for movement and refuge. Care is required to ensure that culverts are bioengineered to ensure that average water velocity is sufficiently low and local hydraulic variation high, the bed and/or sidewalls contain refuge structures, and there are no cross-channel steps in bed level. Smooth-bedded box culverts are unlikely to be suitable for white-clawed crayfish.

  2. Spiral tectonics

    Science.gov (United States)

    Hassan Asadiyan, Mohammad

    2014-05-01

    Spiral Tectonics (ST) is a new window to global tectonics introduced as alternative model for Plate Tectonics (PT). ST based upon Dahw(rolling) and Tahw(spreading) dynamics. Analogues to electric and magnetic components in the electromagnetic theory we could consider Dahw and Tahw as components of geodynamics, when one component increases the other decreases and vice versa. They are changed to each other during geological history. D-component represents continental crust and T-component represents oceanic crust. D and T are two arm of spiral-cell. T-arm 180 degree lags behind D-arm so named Retard-arm with respect to D or Forward-arm. It seems primary cell injected several billions years ago from Earth's center therefore the Earth's core was built up first then mantel and finally the crust was build up. Crust building initiate from Arabia (Mecca). As the universe extended gravitation wave swirled the earth fractaly along cycloid path from big to small scale. In global scale (order-0) ST collect continents in one side and abandoned Pacific Ocean in the other side. Recent researches also show two mantels upwelling in opposite side of the Earth: one under Africa (tectonic pose) and the other under Pacific Ocean (tectonic tail). In higher order (order-1) ST build up Africa in one side and S.America in the other side therefore left Atlantic Ocean meandered in between. In order-n e.g. Khoor Musa and Bandar-Deylam bay are seen meandered easterly in the Iranian part but Khoor Abdullah and Kuwait bay meandered westerly in the Arabian part, they are distributed symmetrically with respect to axis of Persian Gulf(PG), these two are fractal components of easterly Caspian-wing and westerly Black Sea-wing which split up from Anatoly. Caspian Sea and Black Sea make two legs of Y-like structure, this shape completely fitted with GPS-velocity map which start from PG and split up in the Catastrophic Point(Anatoly). We could consider PG as remnants of Ancient Ocean which spent up

  3. Water quality implications of culvert repair options : vinyl ester based and ultraviolet cured-in-place pipe liners.

    Science.gov (United States)

    2012-11-01

    Specifications of the Virginia Department of Transportation (VDOT) allow for the use of several trenchless pipe or : culvert repair technologies whereby existing underground culverts are repaired in place rather than by the use of the conventio...

  4. Culvert flow in small drainages in montane tropical forests: observations from the Luquillo Experimental Forest of Puerto Rico.

    Science.gov (United States)

    F. N. Scatena

    1990-01-01

    This paper describe the hydraulics of unsubmerged flow for 5 culverts in the Luiquillo Esperimental Forest of Puerto Rico. A General equation based on empirical data is presented to estimate culvert discharge during unsubmerged conditions. Large culverts are needed in humid tropical montane areas than in humid temperatute watersheds and are usually appropriate only...

  5. High resolution gamma-ray spectrometry of culverts containing transuranic waste at the Savannah River Site

    International Nuclear Information System (INIS)

    Hofstetter, K.J.; Sigg, R.

    1990-01-01

    A number of concrete culverts used to retrievably store drummed, dry, radioactive waste at the Savannah River Site (SRS), were suspected of containing ambiguous quantities of transuranic (TRU) nuclides. These culverts were assayed in place for Pu-239 content using thermal and fast neutron counting techniques. High resolution gamma-ray spectroscopy on 17 culverts, having neutron emission rates several times higher than expected, showed characteristic gamma-ray signatures of neutron emitters other than Pu-239 (e.g., Pu-238, Pu/Be, or Am/Be neutron sources). This study confirmed the Pu-239 content of the culverts with anomalous neutron rates and established limits on the Pu-239 mass in each of the 17 suspect culverts by in-field, non-intrusive gamma-ray measurements

  6. Silicon Carbide Corrugated Mirrors for Space Telescopes, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Trex Enterprises Corporation (Trex) proposes technology development to manufacture monolithic, lightweight silicon carbide corrugated mirrors (SCCM) suitable for...

  7. Electromagnetohydrodynamic flow through a microparallel channel with corrugated walls

    International Nuclear Information System (INIS)

    Buren, Mandula; Jian, Yongjun; Chang, Long

    2014-01-01

    In this paper a perturbation method is introduced to study the electromagnetohydrodynamic (EMHD) flow in a microparallel channel with slightly corrugated walls. The corrugations of the two walls are periodic sinusoidal waves of small amplitude either in phase or half-period out of phase, and the perturbation solutions of velocity and volume flow rate are obtained. Using numerical computation the effects of the corrugations on the flow are graphically analysed. The results show that the influence of corrugation on the flow decreases with Hartmann number. The phase difference of wall corrugations becomes unimportant when the wavenumber is greater than 3 or when the Hartmann number is greater than 4. With the increase in wavenumber, the decreasing effects of corrugations on the flow increase. When the wavenumber is smaller than the threshold wavenumber (it is a function of Hartmann number) and the wall corrugations are half-period out of phase, the corrugations can enhance the mean velocity of EMHD flow. However, the mean velocity is always decreased when the corrugations are in phase. (paper)

  8. Application of a multistate model to estimate culvert effects on movement of small fishes

    Science.gov (United States)

    Norman, J.R.; Hagler, M.M.; Freeman, Mary C.; Freeman, B.J.

    2009-01-01

    While it is widely acknowledged that culverted road-stream crossings may impede fish passage, effects of culverts on movement of nongame and small-bodied fishes have not been extensively studied and studies generally have not accounted for spatial variation in capture probabilities. We estimated probabilities for upstream and downstream movement of small (30-120 mm standard length) benthic and water column fishes across stream reaches with and without culverts at four road-stream crossings over a 4-6-week period. Movement and reach-specific capture probabilities were estimated using multistate capture-recapture models. Although none of the culverts were complete barriers to passage, only a bottomless-box culvert appeared to permit unrestricted upstream and downstream movements by benthic fishes based on model estimates of movement probabilities. At two box culverts that were perched above the water surface at base flow, observed movements were limited to water column fishes and to intervals when runoff from storm events raised water levels above the perched level. Only a single fish was observed to move through a partially embedded pipe culvert. Estimates for probabilities of movement over distances equal to at least the length of one culvert were low (e.g., generally ???0.03, estimated for 1-2-week intervals) and had wide 95% confidence intervals as a consequence of few observed movements to nonadjacent reaches. Estimates of capture probabilities varied among reaches by a factor of 2 to over 10, illustrating the importance of accounting for spatially variable capture rates when estimating movement probabilities with capture-recapture data. Longer-term studies are needed to evaluate temporal variability in stream fish passage at culverts (e.g., in relation to streamflow variability) and to thereby better quantify the degree of population fragmentation caused by road-stream crossings with culverts. ?? American Fisheries Society 2009.

  9. Observations of barred spirals

    International Nuclear Information System (INIS)

    Elmegreen, D.M.

    1990-01-01

    Observations of barred spiral galaxies are discussed which show that the presence of a bar increases the likelihood for grand design spiral structure only in early Hubble types. This result is contrary to the more common notion that grand design spiral structure generally accompanies bars in galaxies. Enhanced deprojected color images are shown which reveal that a secondary set of spiral arms commonly occurs in barred galaxies and also occasionally in ovally distorted galaxies. 6 refs

  10. On the whistling of corrugated pipes with narrow cavities

    NARCIS (Netherlands)

    Golliard, J.; Belfroid, S.P.C.; González Diez, N.; Bendiksen, E.; Frimodt, C.

    2013-01-01

    Pipes with a corrugated inner surface, as used inflexible pipes for gas production and transport, can be subject to Flow-Induced Pulsations when the flow velocities are higher than a certain onset velocity. The onset velocity for classical corrugated pipes can be predicted on basis of the geometry

  11. Dynamic tension testing equipment for paperboard and corrugated fiberboard

    Science.gov (United States)

    W. D. Godshall

    1965-01-01

    The objective of this work was to develop a method, the testing equipment, and the instrumentation with which dynamic stress-strain information may be obtained for paperboards and built-up corrugated fiberboards as used in corrugated fiberboard containers. Much information is available on the properties of these materials when subjected to static or low rates of...

  12. Numerical Investigation of Corrugated Wire Mesh Laminate

    Directory of Open Access Journals (Sweden)

    Jeongho Choi

    2013-01-01

    Full Text Available The aim of this work is to develop a numerical model of Corrugated Wire Mesh Laminate (CWML capturing all its complexities such as nonlinear material properties, nonlinear geometry and large deformation behaviour, and frictional behaviour. Development of such a model will facilitate numerical simulation of the mechanical behaviour of the wire mesh structure under various types of loading as well as the variation of the CWML configuration parameters to tailor its mechanical properties to suit the intended application. Starting with a single strand truss model consisting of four waves with a bilinear stress-strain model to represent the plastic behaviour of stainless steel, the finite element model is gradually built up to study single-layer structures with 18 strands of corrugated wire meshes consistency and double- and quadruple-layered laminates with alternating crossply orientations. The compressive behaviour of the CWML model is simulated using contact elements to model friction and is compared to the load-deflection behaviour determined experimentally in uniaxial compression tests. The numerical model of the CWML is then employed to conduct the aim of establishing the upper and lower bounds of stiffness and load capacity achievable by such structures.

  13. Thermal performance of a spirally coiled finned tube heat exchanger under wet-surface conditions

    International Nuclear Information System (INIS)

    Wongwises, Somchai; Naphon, Paisarn

    2006-01-01

    This paper is a continuation of the author's previous work on spiral coil heat exchangers. In the present study, the heat transfer characteristics and the performance of a spirally coiled finned tube heat exchanger under wet-surface conditions are theoretically and experimentally investigated. The test section is a spiral-coil heat exchanger which consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled finned tubes. Each tube is fabricated by bending a 9.6 mm diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium crimped spiral fins with thickness of 0.6 mm and outer diameter of 28.4 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Air and water are used as working fluids in shell side and tube side, respectively. The experiments are done under dehumidifying conditions. A mathematical model based on the conservation of mass and energy is developed to simulate the flow and heat transfer characteristics of working fluids flowing through the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data

  14. Determination of entrance loss coefficients for pre-cast reinforced concrete box culverts.

    Science.gov (United States)

    2012-12-01

    There is an increased interest in constructing Pre-Cast (PC) Twin and Triple Reinforced Concrete Box (RCB) culverts : in Iowa due to the efficiency associated with their production in controlled environment and decrease of the construction : time at ...

  15. Software development to implement the TxDOT culvert rating guide.

    Science.gov (United States)

    2013-05-01

    This implementation project created CULVLR: Culvert Load Rating, Version 1.0.0, a Windows-based : desktop application software package that automates the process by which Texas Department of Transportation : (TxDOT) engineers and their consultants ...

  16. Composite corrugated structures for morphing wing skin applications

    International Nuclear Information System (INIS)

    Thill, C; Etches, J A; Bond, I P; Potter, K D; Weaver, P M

    2010-01-01

    Composite corrugated structures are known for their anisotropic properties. They exhibit relatively high stiffness parallel (longitudinal) to the corrugation direction and are relatively compliant in the direction perpendicular (transverse) to the corrugation. Thus, they offer a potential solution for morphing skin panels (MSPs) in the trailing edge region of a wing as a morphing control surface. In this paper, an overview of the work carried out by the present authors over the last few years on corrugated structures for morphing skin applications is first given. The second part of the paper presents recent work on the application of corrugated sandwich structures. Panels made from multiple unit cells of corrugated sandwich structures are used as MSPs in the trailing edge region of a scaled morphing aerofoil section. The aerofoil section features an internal actuation mechanism that allows chordwise length and camber change of the trailing edge region (aft 35% chord). Wind tunnel testing was carried out to demonstrate the MSP concept but also to explore its limitations. Suggestions for improvements arising from this study were deduced, one of which includes an investigation of a segmented skin. The overall results of this study show that the MSP concept exploiting corrugated sandwich structures offers a potential solution for local morphing wing skins for low speed and small air vehicles

  17. Mussel Spat Ropes Assist Redfin Bully Gobiomorphus huttoni Passage through Experimental Culverts with Velocity Barriers

    Directory of Open Access Journals (Sweden)

    Jonathan D. Tonkin

    2012-09-01

    Full Text Available The application of mussel spat rope for enabling the passage of redfin bully Gobiomorphus huttoni through culverts, which create velocity barriers, was trialled in the laboratory. No fish were able to access the un-roped control pipes whereas 52% successfully negotiated the pipes in the rope treatments. The success of fish ascending treatment pipes suggests mussel spat rope may be effective for enabling the passage of this and other similar fish species through otherwise impassable culverts with velocity barriers.

  18. Mathematical Model for Thin-walled Corrugated Tube under Axial Compression

    Directory of Open Access Journals (Sweden)

    Eyvazian Arameh

    2016-01-01

    Full Text Available In this research, theoretical investigation of corrugated aluminum tubes is performed to predicting the energy absorption characteristics. Aim to deform plastic tubes in predetermined intervals, corrugations are introduced on its surface. Theoretical relations are presented for predicting the energy absorption and mean crushing load of corrugated tubes. Other than that, corrugation helps to control the failure mode.

  19. CONTRIBUTIONS ON THE DESIGN OF UNCONVENTIONAL CORRUGATED BOARD STRUCTURES

    Directory of Open Access Journals (Sweden)

    NEIDONI Nadina

    2015-06-01

    Full Text Available The paper depicts a few contributions on the design of several unconventional corrugated board structures. In general, cardboard and corrugated cardboard is strongly linked to packaging. However, limiting these materials to their primary use does nothing else but to restrict the possibilities of using them in other interesting areas. Consequently, new structures built from cardboard have been imagined and in the paper there are presented a few unconventional uses of the corrugated fiberboard, namely as furniture elements, along with the technology used in the design and the manufacturing process.

  20. Where have all the caddis gone? The role of culverts, and spiders

    Science.gov (United States)

    Harding, J. S.; Neumegen, R. E.; van den Braak, I. L.

    2005-05-01

    Restoration of a 1.5 km urban stream over the past five years has led to surprisingly slow improvement in benthic communities. Analysis of benthic invertebrates at six sites longitudinally showed a marked decline in caddisfly diversity and abundance upstream. This decline could not be adequately explained by changes in water quality, or in-stream physical conditions. Extensive adult trapping on multiple sites on three urban streams has shown that main roads with culverts act as barriers to the upstream flight of adult caddisflies. When adult caddis encounter a road culvert, some are distracted by the surrounding urban conditions (e.g. street lights), and only 30-50% enter the culvert. Of these, about 10-30% do not reach the upstream exit falling prey to spiders or distracted by confounding flight cues. Experimental removal of spiders and webs from three culverts showed an increase in the proportion of caddis exiting upstream. Other confounding effects on caddisflies within the culvert might include light, humidity and temperature gradients. Our results indicate that barriers to adult dispersal and colonisation, such as road culverts and confusing urban habitats, may markedly limit the recovery of urban stream communities.

  1. Electromechanics of graphene spirals

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, Topi; Koskinen, Pekka, E-mail: pekka.koskinen@iki.fi [NanoScience Center, Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland)

    2014-12-15

    Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.

  2. Optical properties of nonimaging concentrators with corrugated reflectors

    Science.gov (United States)

    Roennelid, Mats; Perers, Bengt; Karlsson, Bjorn

    1994-09-01

    A ray tracing study has been performed on the optical properties of cylindrical nonimaging concentrators with linear corrugated reflectors. The corrugations are assumed to be V-formed and to have an extension parallel to the meridian plane of the concentrators. It is shown that the acceptance angle for radiation incident in the meridian plane can be increased for moderate corrugations. This increased acceptance is balanced by a decreased acceptance of radiation from other directions. Calculations of angular acceptance for a 2X compound parabolic concentrator is presented. It is shown that the annual irradiation on a solar collector with booster reflector can be increased if corrugated reflectors are used instead of smooth reflectors.

  3. Theoretical prediction on corrugated sandwich panels under bending loads

    Science.gov (United States)

    Shu, Chengfu; Hou, Shujuan

    2018-05-01

    In this paper, an aluminum corrugated sandwich panel with triangular core under bending loads was investigated. Firstly, the equivalent material parameters of the triangular corrugated core layer, which could be considered as an orthotropic panel, were obtained by using Castigliano's theorem and equivalent homogeneous model. Secondly, contributions of the corrugated core layer and two face panels were both considered to compute the equivalent material parameters of the whole structure through the classical lamination theory, and these equivalent material parameters were compared with finite element analysis solutions. Then, based on the Mindlin orthotropic plate theory, this study obtain the closed-form solutions of the displacement for a corrugated sandwich panel under bending loads in specified boundary conditions, and parameters study and comparison by the finite element method were executed simultaneously.

  4. Stylus type MEMS texture sensor covered with corrugated diaphragm

    Science.gov (United States)

    Tsukamoto, Takashiro; Asao, Hideaki; Tanaka, Shuji

    2017-09-01

    In this paper, a stylus type MEMS texture sensor covered with a corrugated palylene diaphragm, which prevent debris from jamming into the sensor without significant degradation of sensitivity and bandwidth, was reported. A new fabrication process using a lost-foil method to make the corrugated diaphragm on a 3-axis piezoresistive force sensor at wafer level has been developed. The texture sensor could detect the surface microstructure as small as about 10 \

  5. Bandwidth Study of the Microwave Reflectors with Rectangular Corrugations

    Science.gov (United States)

    Zhang, Liang; He, Wenlong; Donaldson, Craig R.; Cross, Adrian W.

    2016-09-01

    The mode-selective microwave reflector with periodic rectangular corrugations in the inner surface of a circular metallic waveguide is studied in this paper. The relations between the bandwidth and reflection coefficient for different numbers of corrugation sections were studied through a global optimization method. Two types of reflectors were investigated. One does not consider the phase response and the other does. Both types of broadband reflectors operating at W-band were machined and measured to verify the numerical simulations.

  6. Impact of Corrugated Paperboard Structure on Puncture Resistance

    Directory of Open Access Journals (Sweden)

    Vaidas Bivainis

    2015-03-01

    Full Text Available Thanks to its excellentprotective properties, lightness, a reasonable price, and ecology, corrugated paperboardis one of the most popular materials used in the production of packaging for variousproducts. During transportation or storage, packaging with goods can be exposedto the mass of other commodities, dropping from heights and transportationshock loads, which can lead to their puncture damage. Depending on the purposeand size of the packaging, the thickness, grammage, constituent paper layers,numbers of layers and type of fluting of corrugated paperboard used in itsproduction differ. A standard triangular prism, corrugated paperboard fixationplates and a universal tension-compression machine were used to investigate theimpact of corrugated paperboard structure and other parameters on the punctureresistance of the material. The investigation determines the maximum punctureload and estimates energy required to penetrate the corrugated paperboard. Itwas found that the greatest puncture resistance is demonstrated by paperboardwith a larger number of corrugating flutings and the board produced from harderpaper with a smaller amount of recycled paper. It was established that thegrammage of three-layered paperboard with two different fluting profiles has thegreatest impact on the level of static puncture energy.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5713

  7. Triangular spiral tilings

    International Nuclear Information System (INIS)

    Sushida, Takamichi; Hizume, Akio; Yamagishi, Yoshikazu

    2012-01-01

    The topology of spiral tilings is intimately related to phyllotaxis theory and continued fractions. A quadrilateral spiral tiling is determined by a suitable chosen triple (ζ, m, n), where ζ element of D/R, and m and n are relatively prime integers. We give a simple characterization when (ζ, m, n) produce a triangular spiral tiling. When m and n are fixed, the admissible generators ζ form a curve in the unit disk. The family of triangular spiral tilings with opposed parastichy pairs (m, n) is parameterized by the divergence angle arg (ζ), while triangular spiral tilings with non-opposed parastichy pairs are parameterized by the plastochrone ratio 1/|ζ|. The generators for triangular spiral tilings with opposed parastichy pairs are not dense in the complex parameter space, while those with non-opposed parastichy pairs are dense. The proofs will be given in a general setting of spiral multiple tilings. We present paper-folding (origami) sheets that build spiral towers whose top-down views are triangular tilings. (paper)

  8. Spiral Countercurrent Chromatography

    Science.gov (United States)

    Ito, Yoichiro; Knight, Martha; Finn, Thomas M.

    2013-01-01

    For many years, high-speed countercurrent chromatography conducted in open tubing coils has been widely used for the separation of natural and synthetic compounds. In this method, the retention of the stationary phase is solely provided by the Archimedean screw effect by rotating the coiled column in the centrifugal force field. However, the system fails to retain enough of the stationary phase for polar solvent systems such as the aqueous–aqueous polymer phase systems. To address this problem, the geometry of the coiled channel was modified to a spiral configuration so that the system could utilize the radially acting centrifugal force. This successfully improved the retention of the stationary phase. Two different types of spiral columns were fabricated: the spiral disk assembly, made by stacking multiple plastic disks with single or four interwoven spiral channels connected in series, and the spiral tube assembly, made by inserting the tetrafluoroethylene tubing into a spiral frame (spiral tube support). The capabilities of these column assemblies were successfully demonstrated by separations of peptides and proteins with polar two-phase solvent systems whose stationary phases had not been well retained in the earlier multilayer coil separation column for high-speed countercurrent chromatography. PMID:23833207

  9. Spirals on the sea

    Directory of Open Access Journals (Sweden)

    Walter Munk

    2001-12-01

    Full Text Available Spiral eddies were first seen in the sun glitter on the Apollo Mission 30 years ago; they have since been recorded on SAR missions and in the infrared. The spirals are globally distributed, 10-25 km in size and overwhelmingly cyclonic. They have not been explained. Under light winds favorable to visualization, linear surface features with high surfactant density and low surface roughness are of common occurrence. We have proposed that frontal formations concentrate the ambient shear and prevailing surfactants. Horizontal shear instabilities ensue when the shear becomes comparable to the coriolis frequency. The resulting vortices wind the liner features into spirals. The hypothesis needs to be tested by prolonged measurements and surface truth. Spiral eddies are a manifestation of a sub-mesoscale oceanography associated with upper ocean stirring; dimensional considerations suggest a horizontal diffusivity of order 103 m2 s-1.

  10. Spiral 2 Week

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The main goal of this meeting is to present and discuss the current status of the Spiral-2 project at GANIL in front of a large community of scientists and engineers. Different issues have been tackled particularly the equipment around Spiral-2 like injectors, cryo-modules or beam diagnostics, a workshop was devoted to other facilities dedicated to radioactive ion beam production. This document gathers only the slides of the presentations.

  11. Stacking the Equiangular Spiral

    OpenAIRE

    Agrawal, A.; Azabi, Y. O.; Rahman, B. M.

    2013-01-01

    We present an algorithm that adapts the mature Stack and Draw (SaD) methodology for fabricating the exotic Equiangular Spiral Photonic Crystal Fiber. (ES-PCF) The principle of Steiner chains and circle packing is exploited to obtain a non-hexagonal design using a stacking procedure based on Hexagonal Close Packing. The optical properties of the proposed structure are promising for SuperContinuum Generation. This approach could make accessible not only the equiangular spiral but also other qua...

  12. Spiral 2 Week

    International Nuclear Information System (INIS)

    2007-01-01

    The main goal of this meeting is to present and discuss the current status of the Spiral-2 project at GANIL in front of a large community of scientists and engineers. Different issues have been tackled particularly the equipment around Spiral-2 like injectors, cryo-modules or beam diagnostics, a workshop was devoted to other facilities dedicated to radioactive ion beam production. This document gathers only the slides of the presentations

  13. High-Assurance Spiral

    Science.gov (United States)

    2017-11-01

    HIGH-ASSURANCE SPIRAL CARNEGIE MELLON UNIVERSITY NOVEMBER 2017 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED STINFO...MU 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Carnegie Mellon University 5000 Forbes Ave Pittsburgh, PA 15217 8. PERFORMING ORGANIZATION...Approved for Public Release; Distribution Unlimited. Carnegie Mellon Carnegie Mellon HA SPIRAL Code Synthesis KeYmaera X Hybrid Theorem Prover

  14. High assurance SPIRAL

    Science.gov (United States)

    Franchetti, Franz; Sandryhaila, Aliaksei; Johnson, Jeremy R.

    2014-06-01

    In this paper we introduce High Assurance SPIRAL to solve the last mile problem for the synthesis of high assurance implementations of controllers for vehicular systems that are executed in today's and future embedded and high performance embedded system processors. High Assurance SPIRAL is a scalable methodology to translate a high level specification of a high assurance controller into a highly resource-efficient, platform-adapted, verified control software implementation for a given platform in a language like C or C++. High Assurance SPIRAL proves that the implementation is equivalent to the specification written in the control engineer's domain language. Our approach scales to problems involving floating-point calculations and provides highly optimized synthesized code. It is possible to estimate the available headroom to enable assurance/performance trade-offs under real-time constraints, and enables the synthesis of multiple implementation variants to make attacks harder. At the core of High Assurance SPIRAL is the Hybrid Control Operator Language (HCOL) that leverages advanced mathematical constructs expressing the controller specification to provide high quality translation capabilities. Combined with a verified/certified compiler, High Assurance SPIRAL provides a comprehensive complete solution to the efficient synthesis of verifiable high assurance controllers. We demonstrate High Assurance SPIRALs capability by co-synthesizing proofs and implementations for attack detection and sensor spoofing algorithms and deploy the code as ROS nodes on the Landshark unmanned ground vehicle and on a Synthetic Car in a real-time simulator.

  15. Spiral silicon drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Lutz, G.; Kemmer, J.; Prechtel, U.; Ziemann, T.

    1988-01-01

    An advanced large area silicon photodiode (and x-ray detector), called Spiral Drift Detector, was designed, produced and tested. The Spiral Detector belongs to the family of silicon drift detectors and is an improvement of the well known Cylindrical Drift Detector. In both detectors, signal electrons created in silicon by fast charged particles or photons are drifting toward a practically point-like collection anode. The capacitance of the anode is therefore kept at the minimum (0.1pF). The concentric rings of the cylindrical detector are replaced by a continuous spiral in the new detector. The spiral geometry detector design leads to a decrease of the detector leakage current. In the spiral detector all electrons generated at the silicon-silicon oxide interface are collected on a guard sink rather than contributing to the detector leakage current. The decrease of the leakage current reduces the parallel noise of the detector. This decrease of the leakage current and the very small capacities of the detector anode with a capacitively matched preamplifier may improve the energy resolution of Spiral Drift Detectors operating at room temperature down to about 50 electrons rms. This resolution is in the range attainable at present only by cooled semiconductor detectors. 5 refs., 10 figs

  16. Numerical analysis of beam with sinusoidally corrugated webs

    Science.gov (United States)

    Górecki, Marcin; Pieńko, Michał; Łagoda, GraŻyna

    2018-01-01

    The paper presents numerical tests results of the steel beam with sinusoidally corrugated web, which were performed in the Autodesk Algor Simulation Professional 2010. The analysis was preceded by laboratory tests including the beam's work under the influence of the four point bending as well as the study of material characteristics. Significant web's thickness and use of tools available in the software allowed to analyze the behavior of the plate girder as beam, and also to observe the occurrence of stresses in the characteristic element - the corrugated web. The stress distribution observed on the both web's surfaces was analyzed.

  17. Mass transfer in corrugated-plate membrane modules. I. Hyperfiltration experiments

    NARCIS (Netherlands)

    van der Waal, M.J.; Racz, I.G.

    1989-01-01

    The application of corrugations as turbulence promoters in membrane filtration was studied. This study showed that it is possible to deform an originally flat membrane to a corrugated shape without damaging it. In hyperfiltration experiments using corrugated cellulose acetate membranes it was found

  18. Plasma Generator Using Spiral Conductors

    Science.gov (United States)

    Szatkowski, George N. (Inventor); Dudley, Kenneth L. (Inventor); Ticatch, Larry A. (Inventor); Smith, Laura J. (Inventor); Koppen, Sandra V. (Inventor); Nguyen, Truong X. (Inventor); Ely, Jay J. (Inventor)

    2016-01-01

    A plasma generator includes a pair of identical spiraled electrical conductors separated by dielectric material. Both spiraled conductors have inductance and capacitance wherein, in the presence of a time-varying electromagnetic field, the spiraled conductors resonate to generate a harmonic electromagnetic field response. The spiraled conductors lie in parallel planes and partially overlap one another in a direction perpendicular to the parallel planes. The geometric centers of the spiraled conductors define endpoints of a line that is non-perpendicular with respect to the parallel planes. A voltage source coupled across the spiraled conductors applies a voltage sufficient to generate a plasma in at least a portion of the dielectric material.

  19. Barred spiral structure of galaxies

    International Nuclear Information System (INIS)

    Chen, Z.; Weng, s.; Xu, M.

    1982-01-01

    Observational data indicate the grand design of spiral or barred spiral structure in disk galaxies. The problem of spiral structure has been thoroughly investigated by C. C. Lin and his collaborators, but yet the problem of barred spiral structure has not been investigated systematically, although much work has been done, such as in Ref. 3--7. Using the gasdynamic model for galaxies and a method of integral transform presented in Ref. 1, we investigated the barred spiral structure and obtained an analytical solution. It gives the large-scale pattern of barred-spirals, which is in fairly good agreement with observational data

  20. Aeroacoustics of the swinging corrugated tube: Voice of the Dragon

    NARCIS (Netherlands)

    Nakiboglu, G.; Rudenko, O.; Hirschberg, Abraham

    2012-01-01

    When one swings a short corrugated pipe segment around one’s head, it produces a musically interesting whistling sound. As a musical toy it is called a “Hummer” and as a musical instrument, the “Voice of the Dragon.” The fluid dynamics aspects of the instrument are addressed, corresponding to the

  1. Aeroacoustics of the swinging corrugated tube : voice of the dragon

    NARCIS (Netherlands)

    Nakiboglu, G.; Rudenko, O.; Hirschberg, A.

    2012-01-01

    When one swings a short corrugated pipe segment around one’s head, it produces a musically interesting whistling sound. As a musical toy it is called a "Hummer" and as a musical instrument, the "Voice of the Dragon." The fluid dynamics aspects of the instrument are addressed, corresponding to the

  2. Chiral Magnetic Spirals

    International Nuclear Information System (INIS)

    Basar, Goekce; Dunne, Gerald V.; Kharzeev, Dmitri E.

    2010-01-01

    We argue that the presence of a very strong magnetic field in the chirally broken phase induces inhomogeneous expectation values, of a spiral nature along the magnetic field axis, for the currents of charge and chirality, when there is finite baryon density or an imbalance between left and right chiralities. This 'chiral magnetic spiral' is a gapless excitation transporting the currents of (i) charge (at finite chirality), and (ii) chirality (at finite baryon density) along the direction of the magnetic field. In both cases it also induces in the transverse directions oscillating currents of charge and chirality. In heavy ion collisions, the chiral magnetic spiral possibly provides contributions both to the out-of-plane and the in-plane dynamical charge fluctuations recently observed at BNL RHIC.

  3. The Spiral of Euroscepticism

    DEFF Research Database (Denmark)

    Galpin, Charlotte; Trenz, Hans-Jörg

    2017-01-01

    of Euroscepticism’, taking media autonomy seriously to understand how media logics and selective devices contribute to the shaping of public discourse about the EU. We review the literature on the media and EU legitimacy to show how media frames and their amplification on social media can account for the salience......Media scholars have increasingly examined the effects of a negativity bias that applies to political news. In the ‘spiral of cynicism’, journalist preferences for negative news correspond to public demands for sensational news. We argue that this spiral of cynicism in EU news results in a ‘spiral...... of Eurosceptic opinions in the public sphere that then push parties to contest the EU in predominantly negative terms....

  4. Embracing the Spiral

    Directory of Open Access Journals (Sweden)

    Li Mao

    2016-12-01

    Full Text Available Critical research demands that we interrogate our own positionality and social location. Critical reflexivity is a form of researcher critical consciousness that is constant and dynamic in a complex spiral-like process starting within our own experiences as racialized, gendered, and classed beings embedded in particular sociopolitical contexts. Across diverse critical methodologies, a group of graduate students and their supervisor explored their own conceptualization of the reflexivity spiral by reflecting on how their research motivations and methodologies emerged from their racializing, colonizing, language-learning, parenting, and identity negotiating experiences. In this article, they present a spiral model of the critical reflexivity process, review the literature on reflexivity, and conclude with a description of critical reflexivity as a social practice within a supportive and collaborative graduate school experience.

  5. Heat shrink formation of a corrugated thin film thermoelectric generator

    International Nuclear Information System (INIS)

    Sun, Tianlei; Peavey, Jennifer L.; David Shelby, M.; Ferguson, Scott; O’Connor, Brendan T.

    2015-01-01

    Highlights: • Demonstrate and characterize a thermoelectric generator with a corrugated geometry. • Employ a novel heat shrink fabrication approach compatible with low-cost processing. • Use thermal impedance modeling to explore design potential. • Corrugated design shown to be advantageous for low heat-flux density applications. - Abstract: A thin film thermoelectric (TE) generator with a corrugated architecture is demonstrated formed using a heat-shrink fabrication approach. Fabrication of the corrugated TE structure consists of depositing thin film thermoelectric elements onto a planar non-shrink polyimide substrate that is then sandwiched between two uniaxial stretch-oriented co-polyester (PET) films. The heat shrink PET films are adhered to the polyimide in select locations, such that when the structure is placed in a high temperature environment, the outer films shrink resulting in a corrugated core film and thermoelectric elements spanning between the outer PET films. The module has a cross-plane heat transfer architecture similar to a conventional bulk TE module, but with heat transfer in the plane of the thin film thermoelectric elements, which assists in maintaining a significant temperature difference across the thermoelectric junctions. In this demonstration, Ag and Ni films are used as the thermoelectric elements and a Seebeck coefficient of 14 μV K −1 is measured with a maximum power output of 0.22 nW per couple at a temperature difference of 7.0 K. We then theoretically consider the performance of this device architecture with high performance thermoelectric materials in the heat sink limited regime. The results show that the heat-shrink approach is a simple fabrication method that may be advantageous in large-area, low power density applications. The fabrication method is also compatible with simple geometric modification to achieve various form factors and power densities to customize the TE generator for a range of applications

  6. The spinning ball spiral

    International Nuclear Information System (INIS)

    Dupeux, Guillaume; Le Goff, Anne; Quere, David; Clanet, Christophe

    2010-01-01

    We discuss the trajectory of a fast revolving solid ball moving in a fluid of comparable density. As the ball slows down owing to drag, its trajectory follows an exponential spiral as long as the rotation speed remains constant: at the characteristic distance L where the ball speed is significantly affected by the drag, the bending of the trajectory increases, surprisingly. Later, the rotation speed decreases, which makes the ball follow a second kind of spiral, also described in the paper. Finally, the use of these highly curved trajectories is shown to be relevant to sports.

  7. Shear Behavior of Corrugated Steel Webs in H Shape Bridge Girders

    Directory of Open Access Journals (Sweden)

    Qi Cao

    2015-01-01

    Full Text Available In bridge engineering, girders with corrugated steel webs have shown good mechanical properties. With the promotion of composite bridge with corrugated steel webs, in particular steel-concrete composite girder bridge with corrugated steel webs, it is necessary to study the shear performance and buckling of the corrugated webs. In this research, by conducting experiment incorporated with finite element analysis, the stability of H shape beam welded with corrugated webs was tested and three failure modes were observed. Structural data including load-deflection, load-strain, and shear capacity of tested beam specimens were collected and compared with FEM analytical results by ANSYS software. The effects of web thickness, corrugation, and stiffening on shear capacity of corrugated webs were further discussed.

  8. Are spiral galaxies heavy smokers?

    International Nuclear Information System (INIS)

    Davies, J.; Disney, M.; Phillipps, S

    1990-01-01

    The dustiness of spiral galaxies is discussed. Starburst galaxies and the shortage of truly bright spiral galaxies is cited as evidence that spiral galaxies are far dustier than has been thought. The possibility is considered that the dust may be hiding missing mass

  9. Properties of spiral resonators

    International Nuclear Information System (INIS)

    Haeuser, J.

    1989-10-01

    The present thesis deals with the calculation and the study of the application possibilities of single and double spiral resonators. The main aim was the development and the construction of reliable and effective high-power spiral resonators for the UNILAC of the GSI in Darmstadt and the H - -injector for the storage ring HERA of DESY in Hamburg. After the presentation of the construction and the properties of spiral resonators and their description by oscillating-circuit models the theoretical foundations of the bunching are presented and some examples of a rebuncher and debuncher and their influence on the longitudinal particle dynamics are shown. After the description of the characteristic accelerator quantities by means of an oscillating-circuit model and the theory of an inhomogeneous λ/4 line it is shown, how the resonance frequency and the efficiency of single and double spiral resonators can be calculated from the geometrical quantities of the structure. In the following the dependence of the maximal reachable resonator voltage in dependence on the gap width and the surface of the drift tubes is studied. Furthermore the high-power resonators are presented, which were built for the different applications for the GSI in Darmstadt, DESY in Hamburg, and for the FOM Institute in Amsterdam. (orig./HSI) [de

  10. Tracking Target and Spiral Waves

    DEFF Research Database (Denmark)

    Jensen, Flemming G.; Sporring, Jon; Nielsen, Mads

    2002-01-01

    A new algorithm for analyzing the evolution of patterns of spiral and target waves in large aspect ratio chemical systems is introduced. The algorithm does not depend on finding the spiral tip but locates the center of the pattern by a new concept, called the spiral focus, which is defined...... by the evolutes of the actual spiral or target wave. With the use of Gaussian smoothing, a robust method is developed that permits the identification of targets and spirals foci independently of the wave profile. Examples of an analysis of long image sequences from experiments with the Belousov......–Zhabotinsky reaction catalyzed by ruthenium-tris-bipyridyl are presented. Moving target and spiral foci are found, and the speed and direction of movement of single as well as double spiral foci are investigated. For the experiments analyzed in this paper it is found that the movement of a focus correlates with foci...

  11. The mechanism of selective corrugation removal by KOH anisotropic wet etching

    International Nuclear Information System (INIS)

    Shikida, M; Inagaki, N; Sasaki, H; Amakawa, H; Fukuzawa, K; Sato, K

    2010-01-01

    The mechanism of selective corrugation removal by anisotropic wet etching—which reduces a periodic corrugation, called 'scalloping', formed on the sidewalls of microstructures by the Bosch process in deep reactive-ion etching (D-RIE)—was investigated. In particular, the corrugation-removal mechanism was analyzed by using the etching rate distribution pattern, and two equations for predicting the corrugation-removal time by the etching were derived. A Si{1 0 0} wafer was first etched by D-RIE at a depth of 29.4 µm (60 cycles) to form the corrugation on the sidewall surface. The height and pitch of the corrugation were 196 and 494 nm, respectively. Selective removal of the corrugation by using 50% KOH (40 °C) was experimentally tried. The corrugation formed on Si{1 0 0} sidewall surfaces was gradually reduced in size as the etching progressed, and it was completely removed after 5 min of etching. Similarly, the corrugation formed on a Si{1 1 0} sidewall surface was also selectively removed by KOH etching (etching time: 3 min). The roughness value of the sidewall surface was reduced from 17.6 nm to a few nanometers by the etching. These results confirm that the corrugation-removal mechanism using anisotropic wet etching can be explained in terms of the distribution pattern of etching rate

  12. Design and manufacturing of skins based on composite corrugated laminates for morphing aerodynamic surfaces

    Science.gov (United States)

    Airoldi, Alessandro; Fournier, Stephane; Borlandelli, Elena; Bettini, Paolo; Sala, Giuseppe

    2017-04-01

    The paper discusses the approaches for the design and manufacturing of morphing skins based on rectangular-shaped composite corrugated laminates and proposes a novel solution to prevent detrimental effects of corrugation on aerodynamic performances. Additionally, more complex corrugated shapes are presented and analysed. The manufacturing issues related to the production of corrugated laminates are discussed and tests are performed to compare different solutions and to assess the validity of analytical and numerical predictions. The solution presented to develop an aerodynamically efficient skin consists in the integration of an elastomeric cover in the corrugated laminate. The related manufacturing process is presented and assessed, and a fully nonlinear numerical model is developed and characterized to study the behaviour of this skin concept in different load conditions. Finally, configurations based on combinations of individual rectangular-shaped corrugated panels are considered. Their structural properties are numerically investigated by varying geometrical parameters. Performance indices are defined to compare structural stiffness contributions in non-morphing directions with the ones of conventional panels of the same weight. Numerical studies also show that the extension of the concept to complex corrugated shapes may improve both the design flexibility and some specific performances with respect to rectangular shaped corrugations. The overall results validate the design approaches and manufacturing processes to produce corrugated laminates and indicate that the solution for the integration of an elastomeric cover is a feasible and promising method to enhance the aerodynamic efficiency of corrugated skins.

  13. Measuring autogenous strain of concrete with corrugated moulds

    DEFF Research Database (Denmark)

    Tian, Qian; Jensen, Ole Mejlhede

    2008-01-01

    A reliable technique to quantify autogenous strain is a prerequisite to numerical modeling in stress calculations for high performance concrete. The introducing of a special kind of corrugated tube mould helps to transforming volume strain measurement into liner strain measurement in horizontal...... direction for fluid concrete, which not only realizes the continuous monitoring of the autogenous shrinkage since casting, but also effectively eliminates the disturbance resulting from gravity, temperature variation and mould restraint on measuring results. Based on this measuring technique, this paper...

  14. Dispersion of helically corrugated waveguides: Analytical, numerical, and experimental study

    International Nuclear Information System (INIS)

    Burt, G.; Ronald, K.; Young, A.R.; Phelps, A.D.R.; Cross, A.W.; Konoplev, I.V.; He, W.; Thomson, J.; Whyte, C.G.; Samsonov, S.V.; Denisov, G.G.; Bratman, V.L.

    2004-01-01

    Helically corrugated waveguides have recently been studied for use in various applications such as interaction regions in gyrotron traveling-wave tubes and gyrotron backward-wave oscillators and as a dispersive medium for passive microwave pulse compression. The paper presents a summary of various methods that can be used for analysis of the wave dispersion of such waveguides. The results obtained from an analytical approach, simulations with the three-dimensional numerical code MAGIC, and cold microwave measurements are analyzed and compared

  15. LABORATORY EVALUATION ON PERFORMANCE OF GLASS FIBER REINFORCED PLASTIC MORTAR PIPE CULVERTS

    Directory of Open Access Journals (Sweden)

    Huawang Shi

    2018-04-01

    Full Text Available This paper investigated the performance and behaviour of glass fiber reinforced plastic mortar (FRPM pipes under different loading conditions. FRPM pipes with inner diameter of 1500 mm were prefabricated in factory. Mechanics performance testing (ring and axial compressive strength and elastic modulus, stiffness and fatigue test were carried out in laboratory. Ring stiffness test provided pipe stiffness (PS which is a function of geometry and material type of pipe through parallel plate loading test (PPLT. The fatigue test and micro-structure measure method were used to evaluate the durability effects of FRPM under repeated compression load. Results indicated that FRPM pipes had better mechanic performances as the road culverts under soils. It may be helpful for the design and construction of FRPM culverts.

  16. Fast rail corrugation detection based on texture filtering

    Science.gov (United States)

    Xiao, Jie; Lu, Kaixia

    2018-02-01

    The condition detection of rails in high-speed railway is one of the important means to ensure the safety of railway transportation. In order to replace the traditional manual inspection, save manpower and material resources, and improve the detection speed and accuracy, it is of great significance to develop a machine vision system for locating and identifying defects on rails automatically. Rail defects exhibit different properties and are divided into various categories related to the type and position of flaws on the rail. Several kinds of interrelated factors cause rail defects such as type of rail, construction conditions, and speed and/or frequency of trains using the rail. Rail corrugation is a particular kind of defects that produce an undulatory deformation on the rail heads. In high speed train, the corrugation induces harmful vibrations on wheels and its components and reduces the lifetime of rails. This type of defects should be detected to avoid rail fractures. In this paper, a novel method for fast rail corrugation detection based on texture filtering was proposed.

  17. Theory of static friction: temperature and corrugation effects

    International Nuclear Information System (INIS)

    Franchini, A; Brigazzi, M; Santoro, G; Bortolani, V

    2008-01-01

    We present a study of the static friction, as a function of temperature, between two thick solid slabs. The upper one is formed of light particles and the substrate of heavy particles. We focus our attention on the interaction between the phonon fields of the two blocks and on the interface corrugation, among the various mechanisms responsible for the friction. To give evidence of the role played by the dynamical interaction of the substrate with the upper block, we consider both a substrate formed by fixed atoms and a substrate formed by mobile atoms. To study the effect of the corrugation, we model it by changing the range parameter σ in the Lennard-Jones interaction potential. We found that in the case of the mobile substrate there is a large momentum transfer from the substrate to the upper block. This momentum transfer increases on increasing the temperature and produces a large disorder in the upper block favouring a decrease of the static friction with respect to the case for a rigid substrate. Reducing the corrugation, we found that with a rigid substrate the upper block becomes nearly commensurate, producing an enhancement of the static friction with respect to that with a mobile substrate

  18. Forming Spirals From Shadows

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    What causes the large-scale spiral structures found in some protoplanetary disks? Most models assume theyre created by newly-forming planets, but a new study suggests that planets might have nothing to do with it.Perturbations from Planets?In some transition disks protoplanetary disks with gaps in their inner regions weve directly imaged large-scale spiral arms. Many theories currently attribute the formation of these structures to young planets: either the direct perturbations of a planet embedded in the disk cause the spirals, or theyre indirectly caused by the orbit of a planetary body outside of the arms.Another example of spiral arms detected in a protoplanetary disk, MWC 758. [NASA/ESA/ESO/M. Benisty et al.]But what if you could get spirals without any planets? A team of scientists led by Matas Montesinos (University of Chile) have recently published a study in which they examine what happens to a shadowed protoplanetary disk.Casting Shadows with WarpsIn the teams setup, they envision a protoplanetary disk that is warped: the inner region is slightly tilted relative to the outer region. As the central star casts light out over its protoplanetary disk, this disk warping would cause some regions of the disk to be shaded in a way that isnt axially symmetric with potentially interesting implications.Montesinos and collaborators ran 2D hydrodynamics simulations to determine what happens to the motion of particles within the disk when they pass in and out of the shadowed regions. Since the shadowed regions are significantly colder than the illuminated disk, the pressure in these regions is much lower. Particles are therefore accelerated and decelerated as they pass through these regions, and the lack of axial symmetry causes spiral density waves to form in the disk as a result.Initial profile for the stellar heating rate per unit area for one of the authors simulations. The regions shadowed as a result of the disk warp subtend 0.5 radians each (shown on the left

  19. Theory of spiral structure

    International Nuclear Information System (INIS)

    Lin, C.C.

    1977-01-01

    The density wave theory of galactic spirals has now developed into a form suitable for consideration by experts in Applied Mechanics. On the one hand, comparison of theoretical deductions with observational data has convinced astrophysicists of the validity of the basic physical picture and the calculated results. On the other hand, the dynamical problems of a stellar system, such as those concerning the origin of spiral structure in galaxies, have not been completely solved. This paper reviews the current status of such developments, including a brief summary of comparison with observations. A particularly important mechanism, currently called the mechanism of energy exchange, is described in some detail. The mathematical problems and the physical processes involved are similar to those occurring in certain instability mechanisms in the 'magnetic bottle' designed for plasma containment. Speculations are given on the future developments of the theory and on observational programs. (Auth.)

  20. Spiral 2 workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop.

  1. Spiral nonimaging optical designs

    Science.gov (United States)

    Zamora, Pablo; Benítez, Pablo; Miñano, Juan C.; Vilaplana, Juan

    2011-10-01

    Manufacturing technologies as injection molding or embossing specify their production limits for minimum radii of the vertices or draft angle for demolding, for instance. In some demanding nonimaging applications, these restrictions may limit the system optical efficiency or affect the generation of undesired artifacts on the illumination pattern. A novel manufacturing concept is presented here, in which the optical surfaces are not obtained from the usual revolution symmetry with respect to a central axis (z axis), but they are calculated as free-form surfaces describing a spiral trajectory around z axis. The main advantage of this new concept lies in the manufacturing process: a molded piece can be easily separated from its mold just by applying a combination of rotational movement around axis z and linear movement along axis z, even for negative draft angles. Some of these spiral symmetry examples will be shown here, as well as their simulated results.

  2. Spiral 2 workshop

    International Nuclear Information System (INIS)

    2004-01-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop

  3. Holographic Chiral Magnetic Spiral

    International Nuclear Information System (INIS)

    Kim, Keun-Young; Sahoo, Bindusar; Yee, Ho-Ung

    2010-06-01

    We study the ground state of baryonic/axial matter at zero temperature chiral-symmetry broken phase under a large magnetic field, in the framework of holographic QCD by Sakai-Sugimoto. Our study is motivated by a recent proposal of chiral magnetic spiral phase that has been argued to be favored against previously studied phase of homogeneous distribution of axial/baryonic currents in terms of meson super-currents dictated by triangle anomalies in QCD. Our results provide an existence proof of chiral magnetic spiral in strong coupling regime via holography, at least for large axial chemical potentials, whereas we don't find the phenomenon in the case of purely baryonic chemical potential. (author)

  4. Numerical study on shear resisting mechanism for corroded RC box culverts

    International Nuclear Information System (INIS)

    Matsuo, Toyofumi; Matsumura, Takuro; Iwamori, Akiyuki

    2013-01-01

    This paper discusses the effects of reinforcing steel corrosion on the shear resisting mechanism of RC box culverts and the applicability of the material degradation model in a finite element method. First, in FEM analyses, loss of reinforcement section area and initial tension strain due to reinforcement corrosion, and deteriorated bond characteristics between reinforcement and concrete, were considered. Second, cyclic loading tests using full-scale corroded specimens were numerically analyzed. The analyzed crack patterns and load-displacement relationships up to the maximum load were observed to be in close agreement with the experiment results within the average corrosion ratio of 10% of primary reinforcement. The fact that corrosion cracks can importantly affect the progression of shear cracks and shear strength of RC beams was also found. On the other hand, we established that RC box culverts being statically indeterminate structures, sectional forces are redistributed after cracking damage, and local material deterioration has a minor effect on shear capacity. Furthermore, a parametric study was carried out for corroded RC box culverts using parameters such as size, steel corrosion location, and corrosion level. (author)

  5. Band-notched spiral antenna

    Science.gov (United States)

    Jeon, Jae; Chang, John

    2018-03-13

    A band-notched spiral antenna having one or more spiral arms extending from a radially inner end to a radially outer end for transmitting or receiving electromagnetic radiation over a frequency range, and one or more resonance structures positioned adjacent one or more segments of the spiral arm associated with a notch frequency band or bands of the frequency range so as to resonate and suppress the transmission or reception of electromagnetic radiation over said notch frequency band or bands.

  6. Nature of galaxy spiral arms

    International Nuclear Information System (INIS)

    Efremov, Yu.N.

    1984-01-01

    The nature of galaxy spiral arms is discussed in a popular form. Two approaches in the theory of spiral arms are considered; they are related to the problem of differential galaxy rotation and the spiral structure wave theory. The example of Galaxy M31 is considered to compare the structural peculiarity of its spiral arms with the wave theory predictions. The situation in the central and south-eastern part of arm S4 in Galaxy M31 noted to be completely explained by the wave theory and modern concepts on the origin of massive stars

  7. Measuring nutrient spiralling in streams

    Energy Technology Data Exchange (ETDEWEB)

    Newbold, J D; Elwood, J W; O' Neill, R V; Van Winkle, W

    1981-01-01

    Nutrient cycling in streams involves some downstream transport before the cycle is completed. Thus, the path traveled by a nutrient atom in passing through the cycle can be visualized as a spiral. As an index of the spiralling process, we introduce spiralling length, defined as the average distance associated with one complete cycle of a nutrient atom. This index provides a measure of the utilization of nutrients relative to the available supply from upstream. Using /sup 32/p as a tracer, we estimated a spiralling length of 193 m for phosphorus in a small woodland stream.

  8. Three phase spiral liver Scanning

    International Nuclear Information System (INIS)

    Kanyanja, T.A.

    2006-01-01

    The ability to perform rapid back-to-back spiral acquisitions is an important recent technical advantage of spiral CT. this allows imaging of the upper abdomen (liver) during peak arterial enhancement (arterial phase) and during peak hepatic parenchymal enhancement (portal venous phase). Breatheld spiral CT has completely replaced dynamic incremental CT for evaluation of the liver. in selected patients with hyper vascular metastasis (hepatoma, neuroendocrine tumors, renal cell carcinoma, etc.) a biphasic examination is performed with one spiral acquisition obtained during the hepatic arterial phase and a second acquisition during the portal venous phase

  9. The subtropical nutrient spiral

    Science.gov (United States)

    Jenkins, William J.; Doney, Scott C.

    2003-12-01

    We present an extended series of observations and more comprehensive analysis of a tracer-based measure of new production in the Sargasso Sea near Bermuda using the 3He flux gauge technique. The estimated annually averaged nitrate flux of 0.84 ± 0.26 mol m-2 yr-1 constitutes only that nitrate physically transported to the euphotic zone, not nitrogen from biological sources (e.g., nitrogen fixation or zooplankton migration). We show that the flux estimate is quantitatively consistent with other observations, including decade timescale evolution of the 3H + 3He inventory in the main thermocline and export production estimates. However, we argue that the flux cannot be supplied in the long term by local diapycnal or isopycnal processes. These considerations lead us to propose a three-dimensional pathway whereby nutrients remineralized within the main thermocline are returned to the seasonally accessible layers within the subtropical gyre. We describe this mechanism, which we call "the nutrient spiral," as a sequence of steps where (1) nutrient-rich thermocline waters are entrained into the Gulf Stream, (2) enhanced diapycnal mixing moves nutrients upward onto lighter densities, (3) detrainment and enhanced isopycnal mixing injects these waters into the seasonally accessible layer of the gyre recirculation region, and (4) the nutrients become available to biota via eddy heaving and wintertime convection. The spiral is closed when nutrients are utilized, exported, and then remineralized within the thermocline. We present evidence regarding the characteristics of the spiral and discuss some implications of its operation within the biogeochemical cycle of the subtropical ocean.

  10. Rebuilding Spiral Galaxies

    Science.gov (United States)

    2005-01-01

    Major Observing Programme Leads to New Theory of Galaxy Formation Summary Most present-day large galaxies are spirals, presenting a disc surrounding a central bulge. Famous examples are our own Milky Way or the Andromeda Galaxy. When and how did these spiral galaxies form? Why do a great majority of them present a massive central bulge? An international team of astronomers [1] presents new convincing answers to these fundamental questions. For this, they rely on an extensive dataset of observations of galaxies taken with several space- and ground-based telescopes. In particular, they used over a two-year period, several instruments on ESO's Very Large Telescope. Among others, their observations reveal that roughly half of the present-day stars were formed in the period between 8,000 million and 4,000 million years ago, mostly in episodic burst of intense star formation occurring in Luminous Infrared Galaxies. From this and other evidence, the astronomers devised an innovative scenario, dubbed the "spiral rebuilding". They claim that most present-day spiral galaxies are the results of one or several merger events. If confirmed, this new scenario could revolutionise the way astronomers think galaxies formed. PR Photo 02a/05: Luminosity - Oxygen Abundance Relation for Galaxies (VLT) PR Photo 02b/05: The Spiral Rebuilding Scenario A fleet of instruments How and when did galaxies form? How and when did stars form in these island universes? These questions are still posing a considerable challenge to present-day astronomers. Front-line observational results obtained with a fleet of ground- and space-based telescopes by an international team of astronomers [1] provide new insights into these fundamental issues. For this, they embarked on an ambitious long-term study at various wavelengths of 195 galaxies with a redshift [2] greater than 0.4, i.e. located more than 4000 million light-years away. These galaxies were studied using ESO's Very Large Telescope, as well as the

  11. Spoof surface plasmons propagating along a periodically corrugated coaxial waveguide

    International Nuclear Information System (INIS)

    Talebi, Nahid; Shahabadi, Mahmoud

    2010-01-01

    Using the rigorous mode-matching technique, we have investigated a periodically corrugated perfectly conducting coaxial waveguide for the possibility of propagation of localized spoof surface plasmons. To verify our results, the computed band diagram of the structure has been compared with the one obtained using the body-of-revolution finite-difference time-domain method. The obtained spoof surface plasmon modes have been shown to be highly localized and slowly propagating. Variations of the obtained modal frequencies and mode profiles as a function of the depth and width of the grooves have also been investigated.

  12. Spoof surface plasmons propagating along a periodically corrugated coaxial waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Talebi, Nahid; Shahabadi, Mahmoud, E-mail: n.talebi@ece.ut.ac.i [Photonics Research Laboratory, Center of Excellence for Applied Electromagnetic Systems, School of Electrical and Computer Engineering, University of Tehran, North Kargar Ave., Tehran (Iran, Islamic Republic of)

    2010-04-07

    Using the rigorous mode-matching technique, we have investigated a periodically corrugated perfectly conducting coaxial waveguide for the possibility of propagation of localized spoof surface plasmons. To verify our results, the computed band diagram of the structure has been compared with the one obtained using the body-of-revolution finite-difference time-domain method. The obtained spoof surface plasmon modes have been shown to be highly localized and slowly propagating. Variations of the obtained modal frequencies and mode profiles as a function of the depth and width of the grooves have also been investigated.

  13. Spiral branches and star formation

    International Nuclear Information System (INIS)

    Zasov, A.V.

    1974-01-01

    Origin of spiral branches of galaxies and formation of stars in them are considered from the point of view of the theory of the gravitational gas condensation, one of comparatively young theories. Arguments are presented in favour of the stellar condensation theory. The concept of the star formation of gas is no longer a speculative hypothesis. This is a theory which assumes quantitative verification and explains qualitatively many facts observed. And still our knowledge on the nature of spiral branches is very poor. It still remains vague what processes give origin to spiral branches, why some galaxies have spirals and others have none. And shapes of spiral branches are diverse. Some cases are known when spiral branches spread outside boundaries of galaxies themselves. Such spirals arise exclusively in the region where there are two or some interacting galaxies. Only first steps have been made in the explanation of the galaxy spiral branches, and it is necessary to carry out new observations and new theoretical calculations

  14. Global extinction in spiral galaxies

    NARCIS (Netherlands)

    Tully, RB; Pierce, MJ; Saunders, W; Verheijen, MAW; Witchalls, PL

    Magnitude-limited samples of spiral galaxies drawn from the Ursa Major and Pisces Clusters are used to determine their extinction properties as a function of inclination. Imaging photometry is available for 87 spirals in the B, R, I, and K' bands. Extinction causes systematic scatter in

  15. The perfect shape spiral stories

    CERN Document Server

    Hammer, Øyvind

    2016-01-01

    This book uses the spiral shape as a key to a multitude of strange and seemingly disparate stories about art, nature, science, mathematics, and the human endeavour. In a way, the book is itself organized as a spiral, with almost disconnected chapters circling around and closing in on the common theme. A particular strength of the book is its extremely cross-disciplinary nature - everything is fun, and everything is connected! At the same time, the author puts great emphasis on mathematical and scientific correctness, in contrast, perhaps, with some earlier books on spirals. Subjects include the mathematical properties of spirals, sea shells, sun flowers, Greek architecture, air ships, the history of mathematics, spiral galaxies, the anatomy of the human hand, the art of prehistoric Europe, Alfred Hitchcock, and spider webs, to name a few.

  16. Mass transfer in corrugated-plate membrane modules. II. Ultrafiltration experiments

    NARCIS (Netherlands)

    van der Waal, M.J.; Stevanovic, S.; Racz, I.G.

    1989-01-01

    The application of corrugations as turbulence promoters in membrane filtration was studied. In ultrafiltration experiments with polysulfone membranes using Dextran T70 as solute, it was found that the corrugations result in reduced energy consumption or pressure drop compared with flat membranes at

  17. Direct measurements of acoustic damping and sound amplification in corrugated pipes with flow

    NARCIS (Netherlands)

    Golliard, J.; Belfroid, S.P.C.; Vijlbrief, O.; Lunde, K.

    2015-01-01

    The flow-induced pulsations in corrugated pipes result from a feedback loop between an acoustic resonator and the noise amplification at each shear layer in the axisymmetric cavities forming the corrugations. The quality factor of the resonator is determined by the reflection coefficients at the

  18. Whistling of pipes with narrow corrugations: scale model tests and consequences for carcass design

    NARCIS (Netherlands)

    Golliard, J.; Belfroid, S.P.C.; Bendiksen, E.; Frimodt, C.

    2013-01-01

    Pipes for gas production and transport with a corrugated inner surface, as used in flexible pipes, can be subject to Flow-Induced Pulsations when the flow velocity is larger than a certain velocity. This onset velocity is dependent on the geometry of the corrugations, the operational conditions and

  19. Fish movement ecology in high gradient headwater streams: Its relevance to fish passage restoration through stream culvert barriers

    Science.gov (United States)

    Hoffman, Robert L.; Dunham, Jason B.

    2007-01-01

    Restoration of fish passage through culvert barriers has emerged as a major issue in the Pacific Northwest and nationwide, in part, because of their potential influence on fish movement. Movement is an essential mechanism by which mobile animals acquire the resources necessary for the successful completion of their life-cycles. In this report, we provide a brief review of some essential characteristics of animal movement and examples from a focal group of fishes in Washington State: salmon, trout, and char. We begin by outlining some basic characteristics of animal movement and then apply that foundation to the case of salmonid fishes. Next we consider the consequences of disrupting fish movement with human-constructed barriers, such as culverts. Finally, this body of evidence is summarized, and we propose a short list of what we view as high priority information needs to support more effective restoration of fish passage through culverts.

  20. User’s Guide: Computer Program for Design or Investigation of Orthogonal Culverts (CORTCUL).

    Science.gov (United States)

    1981-03-01

    This report is divided into the following parts: a. Part II describes the general culvert and soil system to be designed or investigated by the...Note that cover dimensions do not affect internal forces calculated by the program. 119. Attention is directed to the reinfor-t ismnt informat ion j...h iug the distribution of special loads. T. ft Waiter Loads a..’ia I water loads are permitted only i n the I NV11S’l IGATIN mode wi th Stanidard

  1. Determination of transfer parameters in corrugated plates exchangers

    International Nuclear Information System (INIS)

    Silva Lima Filho, S. da.

    1984-01-01

    In this work is presented a experimental study about the forced convenction problem in vee-corrugated exchangers, with flow in the transversal sense, and parallel plates exchangers in which the isotermal plate is equivalent to the absobing one and the other plate is adiabatic. Global values of the transfer coefficients were experimentally obtained by application of the Naphthalene Sublimation Technique in accordance with the analogy between heat and mass transfer. The results were expressed in terms of Sh sup(-) /Sc sup(0,4) that according to the analogy is equal the Nu sup(-) / Pr sup(0,4) in function of the Reynolds number. The ratio between the lenght of the channel and the average spacing between plates L/2a was ranged in all the exchangers. Parameters of transfer to angles of 45 0 and 31 0 were determined in the corrugated plates exchangers. The experimental results obtained were analyzed and compared among them. Finally practical applications of these results are presented to heat exchangers with similars geometric characteristics. (Author) [pt

  2. Transfer of hydrogen and helium through corrugated, flexible tubes

    International Nuclear Information System (INIS)

    Schippl, K.

    2001-01-01

    The transfer of liquid gas or cold gas through corrugated tubes is an alternative to rigid systems for the use in reactor technique. Advantages: flexibility for easy installation; these tubes together with their associated terminations and hardware are assembled, leak-tested and evacuated at the factory. This permits simple and cost saving installation on site. All tubes are helium leak-tested with a sensitivity of 10E -9 mbar 1/sec. Following the leak test, the vacuum space is pumped down to the operation vacuum level and properly sealed. The vacuum integrity is guaranteed as a result of the high degree of cleanliness observed during production and from the use of a specially selected better material inside the vacuum space. Disadvantage: pressure is limited to 20 bar. To fulfil all rules of the reactor safety, different tests have to be done. Because of the longitudinal weld of the corrugated tube, a bursting test of different sizes gives the best information of the liability of this kind of tube. It can be shown that the bursting pressure of such a tube is more than 5 times higher than the max. working pressure

  3. Role of Bénard-Marangoni instabilities during solvent evaporation in polymer surface corrugations.

    Science.gov (United States)

    Bassou, N; Rharbi, Y

    2009-01-06

    Film formation through the drying of polymer solutions is a widely used process in laboratories and in many industrial applications such as coatings. One of the main goals of these applications is to control the film surface morphology. In many cases, evaporation has been found to yield corrugated patterns on the free surface of films. This has been interpreted in terms of either mechanical or hydrodynamic instabilities. In this article, we present experimental results where mesoscale 2D well-ordered surface corrugation patterns are formed during solvent evaporation from polystyrene/toluene solutions. The transformation of Benard-Marangoni instabilities into surface corrugation is studied during the entire drying process using particle tracking, 3D morphology analyses, etc. We show that the corrugation wavelength is controlled by the Benard-Marangoni instability, whereas the corrugation amplitude is controlled by a mechanism that involves a high evaporation rate.

  4. Mussel Spat Ropes Assist Redfin Bully Gobiomorphus huttoni Passage through Experimental Culverts with Velocity Barriers

    Directory of Open Access Journals (Sweden)

    Liam A.H. Wright

    2012-09-01

    Full Text Available The application of mussel spat rope for enabling the passage of redfin bully Gobiomorphus huttoni through culverts, which create velocity barriers, was trialled in the laboratory. No fish were able to access the un-roped control pipes whereas 52% successfully negotiated the pipes in the rope treatments. The success of fish ascending treatment pipes suggests mussel spat rope may be effective for enabling the passage of this and other similar fish species through otherwise impassable culverts with velocity barriers.

  5. Lopsided spiral galaxies

    International Nuclear Information System (INIS)

    Jog, Chanda J.; Combes, Francoise

    2009-01-01

    The light distribution in the disks of many galaxies is 'lopsided' with a spatial extent much larger along one half of a galaxy than the other, as seen in M101. Recent observations show that the stellar disk in a typical spiral galaxy is significantly lopsided, indicating asymmetry in the disk mass distribution. The mean amplitude of lopsidedness is 0.1, measured as the Fourier amplitude of the m=1 component normalized to the average value. Thus, lopsidedness is common, and hence it is important to understand its origin and dynamics. This is a new and exciting area in galactic structure and dynamics, in contrast to the topic of bars and two-armed spirals (m=2) which has been extensively studied in the literature. Lopsidedness is ubiquitous and occurs in a variety of settings and tracers. It is seen in both stars and gas, in the outer disk and the central region, in the field and the group galaxies. The lopsided amplitude is higher by a factor of two for galaxies in a group. The lopsidedness has a strong impact on the dynamics of the galaxy, its evolution, the star formation in it, and on the growth of the central black hole and on the nuclear fuelling. We present here an overview of the observations that measure the lopsided distribution, as well as the theoretical progress made so far to understand its origin and properties. The physical mechanisms studied for its origin include tidal encounters, gas accretion and a global gravitational instability. The related open, challenging problems in this emerging area are discussed

  6. Arsia Mons Spiral Cloud

    Science.gov (United States)

    2002-01-01

    One of the benefits of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission is the opportunity to observe how the planet's weather changes during a second full martian year. This picture of Arsia Mons was taken June 19, 2001; southern spring equinox occurred the same day. Arsia Mons is a volcano nearly large enough to cover the state of New Mexico. On this particular day (the first day of Spring), the MOC wide angle cameras documented an unusual spiral-shaped cloud within the 110 km (68 mi) diameter caldera--the summit crater--of the giant volcano. Because the cloud is bright both in the red and blue images acquired by the wide angle cameras, it probably consisted mostly of fine dust grains. The cloud's spin may have been induced by winds off the inner slopes of the volcano's caldera walls resulting from the temperature differences between the walls and the caldera floor, or by a vortex as winds blew up and over the caldera. Similar spiral clouds were seen inside the caldera for several days; we don't know if this was a single cloud that persisted throughout that time or one that regenerated each afternoon. Sunlight illuminates this scene from the left/upper left.Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  7. Polarization study of spiral galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Ward-Thompson, D

    1987-01-01

    Optical polarimetry results are presented for four spiral galaxies: NGC 5194 (M51), NGC 1068, NGC 4565 and NGC 4594 (M104). M51 and NGC 1068 show spiral polarization patterns interpreted as indicating a spiral magnetic field in each case. NGC 4565 and M104 show polarizations in their dust lanes which are parallel to their galactic planes, and which are interpreted in terms of a magnetic field in the plane of each. It is hypothesized that the observed magnetic fields may be linked to galactic shocks. A discussion of the origin of galactic magnetic fields concludes that there is not evidence that necessitates a primordial magnetic field.

  8. Spiral phases of doped antiferromagnets

    International Nuclear Information System (INIS)

    Shraiman, B.I.; Siggia, E.D.

    1990-01-01

    The dipole density field describing the holls in a doped antiferromagnet is considered for law hole density in the semiclassical limit. This yields a phase in which the order parameter is planar and spirals round a fixed direction. The single spiral state breaks the continuous spin rotational symmetry and exhibits long-range order at zero temperature. In it there is a global spin direction as rotation axis. The double spiral state, in which there are two perpendicular directions, is isotropic in both spin and real space. Several results of microscopic calculations, carried out to understand the electronic states, quantum fluctuations, lattice effects and normal mode dynamics, are recapitulated. 8 refs

  9. Flow around a corrugated wing over the range of dragonfly flight

    Science.gov (United States)

    Padinjattayil, Sooraj; Agrawal, Amit

    2017-11-01

    The dragonfly flight is very much affected by the corrugations on their wings. A PIV based study is conducted on a rigid corrugated wing for a range of Reynolds number 300-12000 and three different angles of attack (5°-15°) to understand the mechanism of dragonfly flight better. The study revealed that the shape of the corrugation plays a key role in generating vortices. The vortices trapped in the valleys of corrugation dictates the shape of a virtual airfoil around the corrugated wing. A fluid roller bearing effect is created over the virtual airfoil when the trapped vortices merge with each other. A travelling wave produced by the moving virtual boundary around the fluid roller bearings avoids the formation of boundary layer on the virtual surface, thereby leading to high aerodynamic performance. It is found that the lift coefficient increases as the number of vortices increases on the suction surface. Also, it is shown that the partially merged co- rotating vortices give higher lift as compared to fully merged vortices. Further, the virtual airfoil formed around the corrugated wing is compared with a superhydrophobic airfoil which exhibits slip on its surface; several similarities in their flow characteristics are observed. The corrugated airfoil performs superior to the superhydrophobic airfoil in the aerodynamic efficiency due to the virtual slip caused by the travelling wave.

  10. Spiral-shaped disinfection reactors

    KAUST Repository

    Ghaffour, NorEddine; Ait-Djoudi, Fariza; Naceur, Wahib Mohamed; Soukane, Sofiane

    2015-01-01

    This disclosure includes disinfection reactors and processes for the disinfection of water. Some disinfection reactors include a body that defines an inlet, an outlet, and a spiral flow path between the inlet and the outlet, in which the body

  11. Modeling noncontact atomic force microscopy resolution on corrugated surfaces

    Directory of Open Access Journals (Sweden)

    Kristen M. Burson

    2012-03-01

    Full Text Available Key developments in NC-AFM have generally involved atomically flat crystalline surfaces. However, many surfaces of technological interest are not atomically flat. We discuss the experimental difficulties in obtaining high-resolution images of rough surfaces, with amorphous SiO2 as a specific case. We develop a quasi-1-D minimal model for noncontact atomic force microscopy, based on van der Waals interactions between a spherical tip and the surface, explicitly accounting for the corrugated substrate (modeled as a sinusoid. The model results show an attenuation of the topographic contours by ~30% for tip distances within 5 Å of the surface. Results also indicate a deviation from the Hamaker force law for a sphere interacting with a flat surface.

  12. Thin polymer films on chemically patterned, corrugated substrates

    International Nuclear Information System (INIS)

    Geoghegan, Mark; Wang Chun; Rehse, Nicolaus; Magerle, Robert; Krausch, Georg

    2005-01-01

    We study the effect of a chemical pattern on the wetting and dewetting behaviour of thin polystyrene (PS) films on regularly corrugated silicon substrates. Our results reveal that the film preparation, annealing method, and confinement play a critical role in the final film structure. On evaporating gold on both sides of the facets (such that it covered the crests of the facets, and not the troughs), we observed dewetting, which proceeded to the gold, demonstrating an enthalpic effect contrary to the outcome previously observed when gold was only evaporated on one side of the facet. We also coated the substrate with octadecyltrichlorosilane (OTS); this led to a gold and OTS striped structure. PS films several nanometres thick dewet such substrates, with a preferential direction for dewetting in the direction of the stripes forming droplets of a considerably larger size than the stripes

  13. Numerical investigation of the aerodynamic and structural characteristics of a corrugated wing

    Science.gov (United States)

    Hord, Kyle

    Previous experimental studies on static, bio-inspired corrugated wings have shown that they produce favorable aerodynamic properties such as delayed stall compared to streamlined wings and flat plates at high Reynolds numbers (Re ≥ 4x104). The majority of studies have been carried out with scaled models of dragonfly forewings from the Aeshna Cyanea in either wind tunnels or water channels. In this thesis, the aerodynamics of a corrugated airfoil was studied using computational fluid dynamics methods at a low Reynolds number of 1000. Structural analysis was also performed using the commercial software SolidWorks 2009. The flow field is described by solving the incompressible Navier-Stokes equations on an overlapping grid using the pressure-Poisson method. The equations are discretized in space with second-order accurate central differences. Time integration is achieved through the second-order Crank-Nicolson implicit method. The complex vortex structures that form in the corrugated airfoil valleys and around the corrugated airfoil are studied in detail. Comparisons are made with experimental measurements from corrugated wings and also with simulations of a flat plate. Contrary to the studies at high Reynolds numbers, our study shows that at low Reynolds numbers the wing corrugation does not provide any aerodynamic benefit compared to a smoothed flat plate. Instead, the corrugated profile generates more pressure drag which is only partially offset by the reduction of friction drag, leading to more total drag than the flat plate. Structural analysis shows that the wing corrugation can increase the resistance to bending moments on the wing structure. A smoothed structure has to be three times thicker to provide the same stiffness. It was concluded the corrugated wing has the structural benefit to provide the same resistance to bending moments with a much reduced weight.

  14. Spiral-shaped disinfection reactors

    KAUST Repository

    Ghaffour, Noreddine

    2015-08-20

    This disclosure includes disinfection reactors and processes for the disinfection of water. Some disinfection reactors include a body that defines an inlet, an outlet, and a spiral flow path between the inlet and the outlet, in which the body is configured to receive water and a disinfectant at the inlet such that the water is exposed to the disinfectant as the water flows through the spiral flow path. Also disclosed are processes for disinfecting water in such disinfection reactors.

  15. Geometrical properties of turbulent premixed flames and other corrugated interfaces

    Science.gov (United States)

    Thiesset, F.; Maurice, G.; Halter, F.; Mazellier, N.; Chauveau, C.; Gökalp, I.

    2016-01-01

    This study focuses on the geometrical properties of turbulent flame fronts and other interfaces. Toward that end, we use an original tool based on proper orthogonal decomposition (POD), which is applied to the interface spatial coordinates. The focus is mainly on the degree of roughness of the flame front, which is quantified through the scale dependence of its coverage arclength. POD is first validated by comparing with the caliper technique. Fractal characteristics are extracted in an unambiguous fashion using a parametric expression which appears to be impressively well suited for representing Richardson plots. Then it is shown that, for the range of Reynolds numbers investigated here, the scale-by-scale contribution to the arclength does not comply with scale similarity, irrespectively of the type of similarity which is invoked. The finite ratios between large and small scales, referred to as finite Reynolds number effects, are likely to explain this observation. In this context, the Reynolds number that ought to be achieved for a proper inertial range to be discernible, and for scale similarity to be likely to apply, is calculated. Fractal characteristics of flame folding are compared to available predictions. It is confirmed that the inner cutoff satisfactorily correlates with the Kolmogorov scale while the outer cutoff appears to be proportional to the integral length scale. However, the scaling for the fractal dimension is much less obvious. It is argued that much higher Reynolds numbers have to be reached for drawing firm statements about the evolution (or constancy) of the fractal dimension with respect to flame and flow parameters. Finally, a heuristic phenomenology of corrugated interfaces is highlighted. The degree of generality of the latter phenomenology is confirmed by comparing the folding of different interfaces including a turbulent-nonturbulent interface, a liquid jet destabilized by a surrounding air jet, a cavitating flow, and an isoscalar

  16. 49 CFR 1242.15 - Roadway, tunnels and subways, bridges and culverts, ties, rails, other track material, ballast...

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Roadway, tunnels and subways, bridges and culverts, ties, rails, other track material, ballast, track laying and surfacing, and road property damaged... RAILROADS 1 Operating Expenses-Way and Structures § 1242.15 Roadway, tunnels and subways, bridges and...

  17. Beam Expansion of Blind Spot Detection Radar Antennas Using a Radome with Defected Corrugated Inner Wall

    Directory of Open Access Journals (Sweden)

    Hayeon Kim

    2017-01-01

    Full Text Available A beam expanding radome for 76.5 GHz automotive radar antennas is presented whose inner surface is engraved with corrugations. The radar used for blind spot detection (BSD requires a very wide beam width to ensure longer time for tracking out-of-sight objects. It is found that the corrugations modulate the phase velocities of the waves along the surface, which increases beam width in the far field. In addition, defects in the corrugation increase beam width even further. The presented structure satisfies the beam width requirement while keeping a low profile.

  18. Application of the method of integral equations to calculating the electrodynamic characteristics of periodically corrugated waveguides

    International Nuclear Information System (INIS)

    Belov, V.E.; Rodygin, L.V.; Fil'chenko, S.E.; Yunakovskii, A.D.

    1988-01-01

    A method is described for calculating the electrodynamic characteristics of periodically corrugated waveguide systems. This method is based on representing the field as the solution of the Helmholtz vector equation in the form of a simple layer potential, transformed with the use of the Floquet conditions. Systems of compound integral equations based on a weighted vector function of the simple layer potential are derived for waveguides with azimuthally symmetric and helical corrugations. A numerical realization of the Fourier method is cited for seeking the dispersion relation of azimuthally symmetric waves of a circular corrugated waveguide

  19. A corrugated perfect magnetic conductor surface supporting spoof surface magnon polaritons.

    Science.gov (United States)

    Liu, Liang-liang; Li, Zhuo; Gu, Chang-qing; Ning, Ping-ping; Xu, Bing-zheng; Niu, Zhen-yi; Zhao, Yong-jiu

    2014-05-05

    In this paper, we demonstrate that spoof surface magnon polaritons (SSMPs) can propagate along a corrugated perfect magnetic conductor (PMC) surface. From duality theorem, the existence of surface electromagnetic modes on corrugated PMC surfaces are manifest to be transverse electric (TE) mode compared with the transverse magnetic (TM) mode of spoof surface plasmon plaritons (SSPPs) excited on corrugated perfect electric conductor surfaces. Theoretical deduction through modal expansion method and simulation results clearly verify that SSMPs share the same dispersion relationship with the SSPPs. It is worth noting that this metamaterial will have more similar properties and potential applications as the SSPPs in large number of areas.

  20. Modeling of the plastic flow kinematics in the forming process of the lightweight flange corrugation

    Directory of Open Access Journals (Sweden)

    I. V. Fomenko

    2012-01-01

    Full Text Available The determination of the forming maximum possibilities of the flange corrugation by stretching with a free movement of the billets end in the rigid sectional matrices detachable by the flexible filler.

  1. Axial Crushing Behaviors of Thin-Walled Corrugated and Circular Tubes - A Comparative Study

    Science.gov (United States)

    Reyaz-Ur-Rahim, Mohd.; Bharti, P. K.; Umer, Afaque

    2017-10-01

    With the help of finite element analysis, this research paper deals with the energy absorption and collapse behavior with different corrugated section geometries of hollow tubes made of aluminum alloy 6060-T4. Literature available experimental data were used to validate the numerical models of the structures investigated. Based on the results available for symmetric crushing of circular tubes, models were developed to investigate corrugated thin-walled structures behavior. To study the collapse mechanism and energy absorbing ability in axial compression, the simulation was carried in ABAQUS /EXPLICIT code. In the simulation part, specimens were prepared and axially crushed to one-fourth length of the tube and the energy diagram of crushing force versus axial displacement is shown. The effect of various parameters such as pitch, mean diameter, corrugation, amplitude, the thickness is demonstrated with the help of diagrams. The overall result shows that the corrugated section geometry could be a good alternative to the conventional tubes.

  2. Atom chips in the real world: the effects of wire corrugation

    Science.gov (United States)

    Schumm, T.; Estève, J.; Figl, C.; Trebbia, J.-B.; Aussibal, C.; Nguyen, H.; Mailly, D.; Bouchoule, I.; Westbrook, C. I.; Aspect, A.

    2005-02-01

    We present a detailed model describing the effects of wire corrugation on the trapping potential experienced by a cloud of atoms above a current carrying micro wire. We calculate the distortion of the current distribution due to corrugation and then derive the corresponding roughness in the magnetic field above the wire. Scaling laws are derived for the roughness as a function of height above a ribbon shaped wire. We also present experimental data on micro wire traps using cold atoms which complement some previously published measurements [CITE] and which demonstrate that wire corrugation can satisfactorily explain our observations of atom cloud fragmentation above electroplated gold wires. Finally, we present measurements of the corrugation of new wires fabricated by electron beam lithography and evaporation of gold. These wires appear to be substantially smoother than electroplated wires.

  3. Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

    Science.gov (United States)

    Aravind, N.; Samanta, Amiya K.; Roy, Dilip Kr. Singha; Thanikal, Joseph V.

    2015-01-01

    Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

  4. Influence of presence of inclined centered baffle and corrugation frequency on natural convection heat transfer flow of air inside a square enclosure with corrugated side walls

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Salam Hadi; Jabbar, Mohammed Yousif; Mohamad, Ahmad Saddy [Mechanical Engineering Department, College of Engineering, Babylon University, Babylon Province (Iraq)

    2011-09-15

    The main objective of this study is to investigate the effect of presence of insulated inclined centered baffle and corrugation frequency on the steady natural convection in a sinusoidal corrugated enclosure. The present study is based on such a configuration where the two vertical sinusoidal walls are maintained at constant low temperature whereas a constant heat flux source whose length is 80% of the width of the enclosure is discretely embedded in the bottom wall. The remaining parts of the bottom wall and the top wall are adiabatic. The finite volume method has been used to solve the governing Navier-Stokes and the energy conservation equations of the fluid medium in the enclosure in order to investigate the effects of baffle inclination angles, corrugation frequencies and Grashof numbers on the fluid flow and heat transfer in the enclosure. The values of the governing parameters are the Grashof number Gr (10{sup 3}-10{sup 6}), the corrugation frequencies CF (1, 2 and 3), baffle inclination angles (0 deg. {<=} {phi} {<=} 150 deg.) and Prandtl number Pr (0.71). Results are presented in the form of streamline and isotherm plots. The results of this investigation are illustrated that the average Nusselt number increases with increase in both the Grashof number and corrugation frequency for different baffle inclination angles and the presence of inclined baffle and increasing the corrugation frequency have significant effects on the average Nusselt numbers, streamlines and isotherms inside the enclosure. The obtained numerical results have been compared with literature ones, and it gives a reliable agreement. (authors)

  5. Exergy Based Performance Analysis of Double Flow Solar Air Heater with Corrugated Absorber

    OpenAIRE

    S. P. Sharma; Som Nath Saha

    2017-01-01

    This paper presents the performance, based on exergy analysis of double flow solar air heaters with corrugated and flat plate absorber. A mathematical model of double flow solar air heater based on energy balance equations has been presented and the results obtained have been compared with that of a conventional flat-plate solar air heater. The double flow corrugated absorber solar air heater performs thermally better than the flat plate double flow and conventional flat-plate solar air heate...

  6. Numerical analysis of sandwich beam with corrugated core under three-point bending

    Energy Technology Data Exchange (ETDEWEB)

    Wittenbeck, Leszek [Poznan University of Technology, Institute of Mathematics Piotrowo Street No. 5, 60-965 Poznan (Poland); Grygorowicz, Magdalena; Paczos, Piotr [Poznan University of Technology, Institute of Applied Mechanics Jana Pawla IIStreet No. 24, 60-965 Poznan (Poland)

    2015-03-10

    The strength problem of sandwich beam with corrugated core under three-point bending is presented.The beam are made of steel and formed by three mutually orthogonal corrugated layers. The finite element analysis (FEA) of the sandwich beam is performed with the use of the FEM system - ABAQUS. The relationship between the applied load and deflection in three-point bending is considered.

  7. Atom chips in the real world: the effects of wire corrugation

    OpenAIRE

    Schumm , Thorsten; Estève , Jérôme; Aussibal , Christine; Figl , Cristina; Trebbia , Jean-Baptiste; Nguyen , Hai; Mailly , Dominique; Bouchoule , Isabelle; Westbrook , Christoph I; Aspect , Alain

    2005-01-01

    International audience; We present a detailed model describing the effects of wire corrugation on the trapping potential experienced by a cloud of atoms above a current carrying micro wire. We calculate the distortion of the current distribution due to corrugation and then derive the corresponding roughness in the magnetic field above the wire. Scaling laws are derived for the roughness as a function of height above a ribbon shaped wire. We also present experimental data on micro wire traps u...

  8. Numerical and Experimental Investigations on Mechanical Behavior of Composite Corrugated Core

    Science.gov (United States)

    Dayyani, Iman; Ziaei-Rad, Saeed; Salehi, Hamid

    2012-06-01

    Tensile and flexural characteristics of corrugated laminate panels were studied using numerical and analytical methods and compared with experimental data. Prepreg laminates of glass fiber plain woven cloth were hand-laid by use of a heat gun to ease the creation of the panel. The corrugated panels were then manufactured by using a trapezoidal machined aluminium mould. First, a series of simple tension tests were performed on standard samples to evaluate the material characteristics. Next, the corrugated panels were subjected to tensile and three-point bending tests. The force-displacement graphs were recorded. Numerical and analytical solutions were proposed to simulate the mechanical behavior of the panels. In order to model the energy dissipation due to delamination phenomenon observed in tensile tests in all members of corrugated core, plastic behavior was assigned to the whole geometry, not only to the corner regions. Contrary to the literature, it is shown that the three-stage mechanical behavior of composite corrugated core is not confined to aramid reinforced corrugated laminates and can be observed in other types such as fiber glass. The results reveal that the mechanical behavior of the core in tension is sensitive to the variation of core height. In addition, for the first time, the behavior of composite corrugated core was studied and verified in bending. Finally, the analytical and numerical results were validated by comparing them with experimental data. A good degree of correlation was observed which showed the suitability of the finite element model for predicting the mechanical behavior of corrugated laminate panels.

  9. Plasma influence on the dispersion properties of finite-length, corrugated waveguides

    OpenAIRE

    Shkvarunets, A.; Kobayashi, S.; Weaver, J.; Carmel, Y.; Rodgers, J.; Antonsen, T.; Granatstein, V.L.; Destler, W.W.; Ogura, K.; Minami, K.

    1996-01-01

    We present an experimental study of the electromagnetic properties of transverse magnetic modes in a corrugated-wall cavity filled with a radially inhomogeneous plasma. The shifts of the .resonant frequencies of a finite-length, corrugated cavity were measured as a function of the background plasma density and the dispersion diagram was reconstructed up to a peak plasma density of 1012 em - 3. Good agreement with a calculated dispersion diagram is obtained for plasma densities below 5 X 1011 ...

  10. Plasma influence on the dispersion properties of finite-length, corrugated waveguides

    Science.gov (United States)

    Shkvarunets, A.; Kobayashi, S.; Weaver, J.; Carmel, Y.; Rodgers, J.; Antonsen, T. M., Jr.; Granatstein, V. L.; Destler, W. W.; Ogura, K.; Minami, K.

    1996-03-01

    We present an experimental study of the electromagnetic properties of transverse magnetic modes in a corrugated-wall cavity filled with a radially inhomogeneous plasma. The shifts of the resonant frequencies of a finite-length, corrugated cavity were measured as a function of the background plasma density and the dispersion diagram was reconstructed up to a peak plasma density of 1012 cm-3. Good agreement with a calculated dispersion diagram is obtained for plasma densities below 5×1011 cm-3.

  11. Orientation decoding: Sense in spirals?

    Science.gov (United States)

    Clifford, Colin W G; Mannion, Damien J

    2015-04-15

    The orientation of a visual stimulus can be successfully decoded from the multivariate pattern of fMRI activity in human visual cortex. Whether this capacity requires coarse-scale orientation biases is controversial. We and others have advocated the use of spiral stimuli to eliminate a potential coarse-scale bias-the radial bias toward local orientations that are collinear with the centre of gaze-and hence narrow down the potential coarse-scale biases that could contribute to orientation decoding. The usefulness of this strategy is challenged by the computational simulations of Carlson (2014), who reported the ability to successfully decode spirals of opposite sense (opening clockwise or counter-clockwise) from the pooled output of purportedly unbiased orientation filters. Here, we elaborate the mathematical relationship between spirals of opposite sense to confirm that they cannot be discriminated on the basis of the pooled output of unbiased or radially biased orientation filters. We then demonstrate that Carlson's (2014) reported decoding ability is consistent with the presence of inadvertent biases in the set of orientation filters; biases introduced by their digital implementation and unrelated to the brain's processing of orientation. These analyses demonstrate that spirals must be processed with an orientation bias other than the radial bias for successful decoding of spiral sense. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Road Bridges and Culverts, Bridge dataset only includes bridges maintained by Johnson County Public Works in the unincorporated areas, Published in Not Provided, Johnson County Government.

    Data.gov (United States)

    NSGIC Local Govt | GIS Inventory — Road Bridges and Culverts dataset current as of unknown. Bridge dataset only includes bridges maintained by Johnson County Public Works in the unincorporated areas.

  13. Origins of galactic spiral structures

    International Nuclear Information System (INIS)

    Piddington, J.H.

    1978-01-01

    Theories of galactic structure are reviewed briefly before comparing them with recent observations. Also reviewed is the evidence for an intergalactic magnetic field and its possible effects on gas concentrations and patterns of star creation, including spiral arms. It is then shown that normal spiral galaxies may be divided into the M51-type and others. The rare M51-type have H I gas arms coincident with unusually filamentary and luminous optical arms; they also have a companion galaxy. The remaining great majority of spirals have no well-defined gas arms and their optical arms are irregular, broader and less luminous; they have no companion galaxy. It appears that without exception the half-dozen or so galaxies whose structures appear to support the density-wave theory show one or more of the characteristics of the rare type of spiral, and that 'the three principal confirmations of the spiral-wave idea' (M51, M81, M101) have companions which may account for their arms. Toomre has rejected this idea on the grounds that his models do not agree with the observed structures. It is shown that these models are inadequate in two major respects, and when replaced by magneto-tidal models using non-uniform gas disks one might expect agreement. The original hydromagnetic model of spiral arms is now reserved for non-interacting galaxies, of which M33 might be taken as a prototype. The model predicts broad or 'massive' optical arms and no corresponding arms of neutral hydrogen, as observed. (Auth.)

  14. Dark matter in spiral galaxies

    International Nuclear Information System (INIS)

    Persic, M.; Salucci, P.

    1990-01-01

    The Tully-Fisher relation is used to probe dark matter (DM) in the optical regions of spiral galaxies. By establishing it at several different isophotal radii in an appropriate sample of 58 galaxies with good B-band photometry and rotation curves, it is shown that some of its attributes (such as scatter, residuals, nonlinearity, and bias) dramatically decrease moving from the disk edge inward. This behavior challenges any mass model which assumes no DM or a luminosity-independent DM mass fraction interior to the optical radius of spiral galaxies. 58 refs

  15. Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results

    Science.gov (United States)

    Goldberg, A.; Choi, K. K.; Das, N. C.; La, A.; Jhabvala, M.

    1999-01-01

    The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.

  16. Corrugator Activity Confirms Immediate Negative Affect in Surprise

    Directory of Open Access Journals (Sweden)

    Sascha eTopolinski

    2015-02-01

    Full Text Available The emotion of surprise entails a complex of immediate responses, such as cognitive interruption, attention allocation to, and more systematic processing of the surprising stimulus. All these processes serve the ultimate function to increase processing depth and thus cognitively master the surprising stimulus. The present account introduces phasic negative affect as the underlying mechanism responsible for these consequences. Surprising stimuli are schema-discrepant and thus entail cognitive disfluency, which elicits immediate negative affect. This affect in turn works like a phasic cognitive tuning switching the current processing mode from more automatic and heuristic to more systematic and reflective processing. Directly testing the initial elicitation of negative affect by suprising events, the present experiment presented high and low surprising neutral trivia statements to N = 28 participants while assessing their spontaneous facial expressions via facial electromyography. High compared to low suprising trivia elicited higher corrugator activity, indicative of negative affect and mental effort, while leaving zygomaticus (positive affect and frontalis (cultural surprise expression activity unaffected. Future research shall investigate the mediating role of negative affect in eliciting surprise-related outcomes.

  17. Quasicrystallography on the spiral of Archimedes

    International Nuclear Information System (INIS)

    Bursill, L.A.

    1990-01-01

    The concept of a spiral lattice is discussed. Some examples of known mineral structures, namely clino asbestos, halloysite and cylindrite, are then interpreted in terms of this structural principle. An example of a synthetic sulphide catalyst spiral structure having atomic dimensions is also described. All of these inorganic spiral structures are based on the sprial of Archimedes. The principles for a new type of crystallography, based on the Archimedian spiral, are then presented. 45 refs., 8 figs

  18. Waste paper recycling opportunities for government action. Vol. 4, corrugated waste. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, J.; Love, P.

    1978-01-01

    This study analyzes current and expected corrugated waste market conditions in Canada, with the objective of identifying government initiatives which could permanently increase recovery levels. Short-term, practical measures are featured. National and regional demand, generation and recovery levels are examined, along with imports and exports to the USA. Over 70% of corrugated waste is consumed in Ontario and Quebec, and most of this waste is generated in those two provinces. Average recovery rates in most major urban areas are estimated at 30-40%. Future demand, generation, and recovery are estimated, and it is suggested that there will be enough domestic demand to permit reclamation of nearly 35% of Canada's total corrugated wastes. This potential level is not expected to change significantly, and new demand opportunities appear minimal. Examination of the potential for future imports from the USA indicates that availability will tighten over the medium term, necessitating a search for new corrugated waste supply sources. Possible sources include supermakets, retail chains and large assembly manufacturing establishments; one of the most promising of these sources is shopping malls, and a study is appended which examines the feasibility of a corrugated waste source separation program within a hypothetical mall. Possible government actions are outlined to improve reclamation and recycling of corrugated waste in Canada, including the improvement of local recovery capabilities in British Columbia, Ontario and Quebec, and the reduction of freight costs for moving corrugated waste from low-recovery areas to high-demand areas. 26 refs., 9 figs., 31 tabs.

  19. Heat transfer enhancement and pumping power optimization using CuO-water nanofluid through rectangular corrugated pipe

    Science.gov (United States)

    Salehin, Musfequs; Ehsan, Mohammad Monjurul; Islam, A. K. M. Sadrul

    2017-06-01

    Heat transfer enhancement by corrugation in fluid domain is a popular method. The rate of improvement is more when it is used highly thermal conductive fluid as heating or cooling medium. In this present study, heat transfer augmentation was investigated numerically by implementing corrugation in the fluid domain and nanofluid as the base fluid in the turbulent forced convection regime. Finite volume method (FVM) was applied to solve the continuity, momentum and energy equations. All the numerical simulations were considered for single phase flow. A rectangle corrugated pipe with 5000 W/m2 constant heat flux subjected to the corrugated wall was considered as the fluid domain. In the range of Reynolds number 15000 to 40000, thermo-physical and hydrodynamic behavior was investigated by using CuO-water nanofluid from 1% to 5% volume fraction as the base fluid through the corrugated fluid domain. Corrugation justification was performed by changing the amplitude of the corrugation and the corrugation wave length for obtaining the increased heat transfer rate with minimum pumping power. For using CuO-water nanofluid, augmentation was also found more in the rectangle corrugated pipe both in heat transfer and pumping power requirement with the increase of Reynolds number and the volume fraction of nanofluid. For the increased pumping power, optimization of pumping power by using nanofluid was also performed for economic finding.

  20. A study of spiral galaxies

    International Nuclear Information System (INIS)

    Wevers, B.M.H.R.

    1984-01-01

    Attempts have been made to look for possible correlations between integral properties of spiral galaxies as a function of morphological type. To investigate this problem, one needs the detailed distribution of both the gaseous and the stellar components for a well-defined sample of spiral galaxies. A sample of about 20 spiral galaxies was therefore defined; these galaxies were observed in the 21 cm neutral hydrogen line with the Westerbork Synthesis Radio Telescope and in three broad-band optical colours with the 48-inch Palomar Smidt Telescope. First, an atlas of the combined radio and optical observations of 16 nearby northern-hemisphere spiral galaxies is presented. Luminosity profiles are discussed and the scale lengths of the exponential disks and extrapolated central surface brightnesses are derived, as well as radial color distributions; azimuthal surface brightness distributions and rotation curves. Possible correlations with optical features are investigated. It is found that 20 to 50 per cent of the total mass is in the disk. (Auth.)

  1. The Spiral Pattern During Development*

    African Journals Online (AJOL)

    1971-08-07

    Aug 7, 1971 ... which are destined to become the limb areas bud out laterally. Fig. 8. The early cells, which are destined to develop into the upper and the lower limbs, after lateral budding has occurred. Fig. 11 demonstrates the human embryo of about 5 mm. CR length and age of about 32 days. The spiral pattern is.

  2. TESTING THEORIES IN BARRED-SPIRAL GALAXIES

    International Nuclear Information System (INIS)

    Martínez-García, Eric E.

    2012-01-01

    According to one version of the recently proposed 'manifold' theory that explains the origin of spirals and rings in relation to chaotic orbits, galaxies with stronger bars should have a higher spiral arms pitch angle when compared to galaxies with weaker bars. A subsample of barred-spiral galaxies in the Ohio State University Bright Galaxy Survey was used to analyze the spiral arms pitch angle. These were compared with bar strengths taken from the literature. It was found that the galaxies in which the spiral arms maintain a logarithmic shape for more than 70° seem to corroborate the predicted trend.

  3. Efficiency enhancement of flexible OLEDs by using nano-corrugated substrates and conformal Ag transparent anodes

    Science.gov (United States)

    Wang, Li; Luo, Yu; Feng, Xueming; Pei, Yuechen; Lu, Bingheng; Cheng, Shenggui

    2018-05-01

    In flexible OLEDs (FOLEDs), the traditional ITO anode has disadvantages such as refractive-index mismatches among substrate and other functional layers, leads to light loss of nearly 80%, meanwhile, its brittle nature and lack in raw materials hinder its further applications. We investigated an efficient FOLED using a semi-transparent silver (Ag) anode, whereas the device was built on a nano-corrugated flexible polycarbonate (PC) substrate prepared by thermal nanoimprint lithography. The corrugations were well preserved on each layer of the device, both the micro-cavity effect and surface plasmon polariton (SPP) modes of light loss were effectively suppressed. As a result, the current efficiency of the FOLED using a conformal corrugated Ag anode enhanced by 100% compared with a planar Ag anode device, and enhanced by 13% with conventional ITO device. In addition, owing to the quasi-periodical arrangements of the corrugations, the device achieved broad spectra and Lambertian angular emission. The Ag anode significantly improved the bending properties of the OLED as compared to the conventional ITO device, leading to a longer lifetime in practical use. The proposed manufacturing strategy will be useful for fabricating nano corrugations on plastic substrate of FOLED in a cost-effective and convenient manner.

  4. Constructive fire protection of steel corrugated beams of buildings and other structures

    Directory of Open Access Journals (Sweden)

    Ilyin Nikolay

    2017-01-01

    Full Text Available The research introduces a methodology of establishing indicators of fire safety of a building in relation to a guaranteed duration of steel fire-proof corrugated beams resistance in conditions of standard fire tests. Indicators of fire safety are also established in the assessment of design limits of steel fire-proof corrugated beams during design process, construction or maintenance of the building as well as in reducing economic costs when testing steel structures for fire resisting property. The suggested methodology introduces the system of actions aimed to design constructive fire protection of steel corrugated beams of buildings. Technological effect is achieved by conducting firing tests of steel construction by non-destructive methods; the evaluation of fire resistance of fire-proof elements of corrugated beams (corrugated web, upper and lower shelves is identified by the least fire-proof element of a welded I-beam. In this methodology fire resistance duration of the constituent elements of a welded I-beam with account of its fire protection ability is described with an analytic function taken as variables. These variables are intensity strength of stresses and the degree of fire protection of a compound element.

  5. Fracture Behaviours in Compression-loaded Triangular Corrugated Core Sandwich Panels

    Directory of Open Access Journals (Sweden)

    Zaid N.Z.M.

    2016-01-01

    Full Text Available The failure modes occurring in sandwich panels based on the corrugations of aluminium alloy, carbon fibre-reinforced plastic (CFRP and glass fibre-reinforced plastic (GFRP are analysed in this work. The fracture behaviour of these sandwich panels under compressive stresses is determined through a series of uniform lateral compression performed on samples with different cell wall thicknesses. Compression test on the corrugated-core sandwich panels were conducted using an Instron series 4505 testing machine. The post-failure examinations of the corrugated-core in different cell wall thickness were conducted using optical microscope. Load-displacement graphs of aluminium alloy, GFRP and CFRP specimens were plotted to show progressive damage development with five unit cells. Four modes of failure were described in the results: buckling, hinges, delamination and debonding. Each of these failure modes may dominate under different cell wall thickness or loading condition, and they may act in combination. The results indicate that thicker composites corrugated-core panels tend can recover more stress and retain more stiffness. This analysis provides a valuable insight into the mechanical behaviour of corrugated-core sandwich panels for use in lightweight engineering applications.

  6. Efficiency enhancement of flexible OLEDs by using nano-corrugated substrates and conformal Ag transparent anodes

    Directory of Open Access Journals (Sweden)

    Li Wang

    2018-05-01

    Full Text Available In flexible OLEDs (FOLEDs, the traditional ITO anode has disadvantages such as refractive-index mismatches among substrate and other functional layers, leads to light loss of nearly 80%, meanwhile, its brittle nature and lack in raw materials hinder its further applications. We investigated an efficient FOLED using a semi-transparent silver (Ag anode, whereas the device was built on a nano-corrugated flexible polycarbonate (PC substrate prepared by thermal nanoimprint lithography. The corrugations were well preserved on each layer of the device, both the micro-cavity effect and surface plasmon polariton (SPP modes of light loss were effectively suppressed. As a result, the current efficiency of the FOLED using a conformal corrugated Ag anode enhanced by 100% compared with a planar Ag anode device, and enhanced by 13% with conventional ITO device. In addition, owing to the quasi-periodical arrangements of the corrugations, the device achieved broad spectra and Lambertian angular emission. The Ag anode significantly improved the bending properties of the OLED as compared to the conventional ITO device, leading to a longer lifetime in practical use. The proposed manufacturing strategy will be useful for fabricating nano corrugations on plastic substrate of FOLED in a cost-effective and convenient manner.

  7. Interaction of multiarmed spirals in bistable media.

    Science.gov (United States)

    He, Ya-feng; Ai, Bao-quan; Liu, Fu-cheng

    2013-05-01

    We study the interaction of both dense and sparse multiarmed spirals in bistable media modeled by equations of the FitzHugh-Nagumo type. A dense one-armed spiral is characterized by its fixed tip. For dense multiarmed spirals, when the initial distance between tips is less than a critical value, the arms collide, connect, and disconnect continuously as the spirals rotate. The continuous reconstruction between the front and the back drives the tips to corotate along a rough circle and to meander zigzaggedly. The rotation frequency of tip, the frequency of zigzagged displacement, the frequency of spiral, the oscillation frequency of media, and the number of arms satisfy certain relations as long as the control parameters of the model are fixed. When the initial distance between tips is larger than the critical value, the behaviors of individual arms within either dense or sparse multiarmed spirals are identical to that of corresponding one-armed spirals.

  8. Experimental study on the heat transfer characteristics in corrugated and flat plate type heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Hun; Jeong, Yong Ki; Jeon, Chung Hwan; Chang, Young June [Busan National Univ., Busan (Korea, Republic of); Lim, Hyeok [DHT, Busan (Korea, Republic of)

    2003-07-01

    An experiment was performed to study heat transfer characteristics between corrugated heat exchanger and flat plate type one. While heat capacity(13.86kW) was provided constantly and the flow speed was varied from 2.8 to 17.9m/s, the temperature and the pressure drop were measured. Furthermore, heat transfer coefficient, Colburn factor and Nusselt number were calculated using them. With increase of the flow speed for both exchangers, the coefficient and the pressure drop increased, but Colburn factor decreased. The coefficient, pressure drop and Colburn factor of the corrugated type were all higher than those of the flat one, which is due to the flow interruption with recirculation and reattachment of the corrugated type. The empirical correlations of Nusselt number were suggested for the tested two heat exchangers.

  9. Effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure

    Directory of Open Access Journals (Sweden)

    Zaid N.Z.M.

    2017-01-01

    Full Text Available Sandwich structure is an attractive alternative that increasingly used in the transportation and aerospace industry. Corrugated-core with trapezoidal shape allows enhancing the damage resistance to the sandwich structure, but on the other hand, it changes the structural response of the sandwich structure. The aim of this paper is to study the effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure under compression loading. The corrugated-core specimen was fabricated using press technique, following the shape of trapezoidal shape. Two different materials were used in the study, glass fibre reinforced plastic (GFRP and carbon fibre reinforced plastic (CFRP. The result shows that the mechanical properties of the core in compression loading are sensitive to the variation of a number of unit cells and the core thickness.

  10. A magnetically tunable non-Bragg defect mode in a corrugated waveguide filled with liquid crystals

    Science.gov (United States)

    Zhang, Lu; Fan, Ya-Xian; Liu, Huan; Han, Xu; Lu, Wen-Qiang; Tao, Zhi-Yong

    2018-04-01

    A magnetically tunable, non-Bragg defect mode (NBDM) was created in the terahertz frequency range by inserting a defect in the middle of a periodically corrugated waveguide filled with liquid crystals (LCs). In the periodic waveguide, non-Bragg gaps beyond the Bragg ones, which appear in the transmission spectra, are created by different transverse mode resonances. The transmission spectra of the waveguide containing a defect showed that a defect mode was present inside the non-Bragg gap. The NBDM has quite different features compared to the Bragg defect mode, which includes more complex, high-order guided wave modes. In our study, we filled the corrugated waveguide with LCs to realize the tunability of the NBDM. The simulated results showed that the NBDM in a corrugated waveguide filled with LCs can be used in filters, sensors, switches, and other terahertz integrated devices.

  11. Low surface brightness spiral galaxies

    International Nuclear Information System (INIS)

    Romanishin, W.

    1980-01-01

    This dissertation presents an observational overview of a sample of low surface brightness (LSB) spiral galaxies. The sample galaxies were chosen to have low surface brightness disks and indications of spiral structure visible on the Palomar Sky Survey. They are of sufficient angular size (diameter > 2.5 arcmin), to allow detailed surface photometry using Mayall 4-m prime focus plates. The major findings of this dissertation are: (1) The average disk central surface brightness of the LSB galaxies is 22.88 magnitude/arcsec 2 in the B passband. (2) From broadband color measurements of the old stellar population, we infer a low average stellar metallicity, on the order of 1/5 solar. (3) The spectra and optical colors of the HII regions in the LSB galaxies indicate a lack of hot ionizing stars compared to HII regions in other late-type galaxies. (4) The average surface mass density, measured within the radius containing half the total mass, is less than half that of a sample of normal late-type spirals. (5) The average LSB galaxy neutral hydrogen mass to blue luminosity ratio is about 0.6, significantly higher than in a sample of normal late-type galaxies. (6) We find no conclusive evidence of an abnormal mass-to-light ratio in the LSB galaxies. (7) Some of the LSB galaxies exhibit well-developed density wave patterns. (8) A very crude calculation shows the lower metallicity of the LSB galaxies compared with normal late-type spirals might be explained simply by the deficiency of massive stars in the LSB galaxies

  12. Dynamical models of spiral galaxies

    International Nuclear Information System (INIS)

    Grosbol, P.

    1990-01-01

    The effects of changing the basic parameters of rotation curve steepness, amount of bulge, and pitch angle of the imposed spiral pattern in the galactic model of Contoupolos and Grosbel (1986) are investigated. The general conclusions of the model are confirmed and shown to be insensitive to the specific choice of parameters for the galactic potential. The exact amplitude at which the nonlinear effects at the 4:1 resonance become important do, however, depend on the model

  13. Enhanced heat transfer with corrugated flow channel in anode side of direct methanol fuel cells

    International Nuclear Information System (INIS)

    Heidary, H.; Abbassi, A.; Kermani, M.J.

    2013-01-01

    Highlights: • Effect of corrugated flow channel on the heat exchange of DMFC is studied. • Corrugated boundary (except rectangular type) increase heat transfer up to 90%. • Average heat transfer in rectangular-corrugated boundary is less than straight one. • In Re > 60, wavy shape boundary has highest heat transfer. • In Re < 60, triangular shape boundary has highest heat transfer. - Abstract: In this paper, heat transfer and flow field analysis in anode side of direct methanol fuel cells (DMFCs) is numerically studied. To enhance the heat exchange between bottom cold wall and core flow, bottom wall of fluid delivery channel is considered as corrugated boundary instead of straight (flat) one. Four different shapes of corrugated boundary are recommended here: rectangular shape, trapezoidal shape, triangular shape and wavy (sinusoidal) shape. The top wall of the channel (catalyst layer boundary) is taken as hot boundary, because reaction occurs in catalyst layer and the bottom wall of the channel is considered as cold boundary due to coolant existence. The governing equations are numerically solved in the domain by the control volume approach based on the SIMPLE technique (1972). A wide spectrum of numerical studies is performed over a range of various shape boundaries, Reynolds number, triangle block number, and the triangle block amplitude. The performed parametric studies show that corrugated channel with trapezoidal, triangular and wavy shape enhances the heat exchange up to 90%. With these boundaries, cooling purpose of reacting flow in anode side of DMFCs would be better than straight one. Also, from the analogy between the heat and mass transfer problems, it is expected that the consumption of reacting species within the catalyst layer of DMFCs enhance. The present work provides helpful guidelines to the bipolar plate manufacturers of DMFCs to considerably enhance heat transfer and performance of the anode side of DMFC

  14. [Progressive damage monitoring of corrugated composite skins by the FBG spectral characteristics].

    Science.gov (United States)

    Zhang, Yong; Wang, Bang-Feng; Lu, Ji-Yun; Gu, Li-Li; Su, Yong-Gang

    2014-03-01

    In the present paper, a method of monitoring progressive damage of composite structures by non-uniform fiber Bragg grating (FBG) reflection spectrum is proposed. Due to the finite element analysis of corrugated composite skins specimens, the failure process under tensile load and corresponding critical failure loads of corrugated composite skin was predicated. Then, the non-uniform reflection spectrum of FBG sensor could be reconstructed and the corresponding relationship between layer failure order sequence of corrugated composite skin and FBG sensor reflection spectrums was acquired. A monitoring system based on FBG non-uniform reflection spectrum, which can be used to monitor progressive damage of corrugated composite skins, was built. The corrugated composite skins were stretched under this FBG non-uniform reflection spectrum monitoring system. The results indicate that real-time spectrums acquired by FBG non-uniform reflection spectrum monitoring system show the same trend with the reconstruction reflection spectrums. The maximum error between the corresponding failure and the predictive value is 8.6%, which proves the feasibility of using FBG sensor to monitor progressive damage of corrugated composite skin. In this method, the real-time changes in the FBG non-uniform reflection spectrum within the scope of failure were acquired through the way of monitoring and predicating, and at the same time, the progressive damage extent and layer failure sequence of corru- gated composite skin was estimated, and without destroying the structure of the specimen, the method is easy and simple to operate. The measurement and transmission section of the system are completely composed of optical fiber, which provides new ideas and experimental reference for the field of dynamic monitoring of smart skin.

  15. Multiple mechanisms quench passive spiral galaxies

    Science.gov (United States)

    Fraser-McKelvie, Amelia; Brown, Michael J. I.; Pimbblet, Kevin; Dolley, Tim; Bonne, Nicolas J.

    2018-02-01

    We examine the properties of a sample of 35 nearby passive spiral galaxies in order to determine their dominant quenching mechanism(s). All five low-mass (M⋆ environments. We postulate that cluster-scale gas stripping and heating mechanisms operating only in rich clusters are required to quench low-mass passive spirals, and ram-pressure stripping and strangulation are obvious candidates. For higher mass passive spirals, while trends are present, the story is less clear. The passive spiral bar fraction is high: 74 ± 15 per cent, compared with 36 ± 5 per cent for a mass, redshift and T-type matched comparison sample of star-forming spiral galaxies. The high mass passive spirals occur mostly, but not exclusively, in groups, and can be central or satellite galaxies. The passive spiral group fraction of 74 ± 15 per cent is similar to that of the comparison sample of star-forming galaxies at 61 ± 7 per cent. We find evidence for both quenching via internal structure and environment in our passive spiral sample, though some galaxies have evidence of neither. From this, we conclude no one mechanism is responsible for quenching star formation in passive spiral galaxies - rather, a mixture of mechanisms is required to produce the passive spiral distribution we see today.

  16. Comparison of heat transfer in straight and corrugated minichannels with two-phase flow

    Directory of Open Access Journals (Sweden)

    Peukert P.

    2014-03-01

    Full Text Available Measurements of heat transfer rates performed with an experimental condensation heat exchanger are reported for a corrugated minichannel tube and for a straight minichannel tube. The two cases were compared at same flow regimes. The corrugation appears advantageous for relatively low steam pressures and flow rates where much higher heat transfer rates were observed close to the steam entrance, thus allowing shortening the heat exchanger with the associated advantages of costs lowering and smaller built-up space. At high steam pressures and high flow rates both tubes performed similarly.

  17. Graphene-assisted near-field radiative heat transfer between corrugated polar materials

    International Nuclear Information System (INIS)

    Liu, X. L.; Zhang, Z. M.

    2014-01-01

    Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

  18. Numerical Investigation of Structural Response of Corrugated Blast Wall Depending on Blast Load Pulse Shapes

    Directory of Open Access Journals (Sweden)

    Jung Min Sohn

    Full Text Available Abstract Hydrocarbon explosions are one of most hazardous events for workers on offshore platforms. To protect structures against explosion loads, corrugated blast walls are typically installed. However, the profiles of real explosion loads are quite different depending on the congestion and confinement of Topside structures. As the level of congestion and confinement increases, the explosion load increases by up to 8 bar, and the rising time of the load decreases. This study primarily aims to investigate the structural behavior characteristics of corrugated blast walls under different types of explosion loadings. Four loading shapes were applied in the structural response analysis, which utilized a dynamic nonlinear finite element method.

  19. Corrugated thimble tube for controlling control rod descent in nuclear reactor

    International Nuclear Information System (INIS)

    Luetzow, H.J.

    1981-01-01

    A thimble tube construction is described which will provide a controlled descent for a control rod while minimizing the reaction forces which must be absorbed by the thimble tube and reducing the possibility that a foreign particle could interfere with the free descent of a control rod. A thimble tube is formed with helically-corrugate internal walls which cooperate with a control rod contained in the tube in an emergency situation to provide a progressively-increasing hydraulic restraining force as each adjacent corrugation is encountered

  20. Squeezed-light generation in a nonlinear planar waveguide with a periodic corrugation

    International Nuclear Information System (INIS)

    Perina, Jan Jr.; Haderka, Ondrej; Sibilia, Concita; Bertolotti, Mario; Scalora, Michael

    2007-01-01

    Two-mode nonlinear interaction (second-harmonic and second-subharmonic generation) in a planar waveguide with a small periodic corrugation at the surface is studied. Scattering of the interacting fields on the corrugation leads to constructive interference that enhances the nonlinear process provided that all the interactions are phase matched. Conditions for the overall phase matching are found. Compared with a perfectly quasi-phase-matched waveguide, better values of squeezing as well as higher intensities are reached under these conditions. Procedure for finding optimum values of parameters for squeezed-light generation is described

  1. Characterisation of Beaver Habitat Parameters That Promote the Use of Culverts as Dam Construction Sites: Can We Limit the Damage to Forest Roads?

    Directory of Open Access Journals (Sweden)

    Geneviève Tremblay

    2017-12-01

    Full Text Available The use of forest roads as foundations for dam construction by beavers is a recurrent problem in the management of forest road networks. In order to limit the damage to forest roads, our goal was to calculate the probability of beaver dam installation on culverts, according to surrounding habitat parameters, which could allow for improvement in the spatial design of new roads that minimise conflicts with beavers. Comparisons of culverts with (n = 77 and without (n = 51 dams in northwestern Quebec showed that catchment surface, cumulate length of all local streams within a 2-km radius, and road embankment height had a negative effect on the probability of dam construction on culverts, while flow level and culvert diameter ratio had a positive effect. Nevertheless, predicted probabilities of dam construction on culverts generally exceeded 50%, even on sites that were less favourable to beavers. We suggest that it would be more reasonable to take their probable subsequent presence into account at the earliest steps of road conception. Installing mitigation measures such as pre-dams during road construction would probably reduce the occurrence of conflicts with beavers and thus reduce the maintenance costs of forest roads.

  2. Collective excitations in itinerant spiral magnets

    International Nuclear Information System (INIS)

    Kampf, A.P.

    1996-01-01

    We investigate the coupled charge and spin collective excitations in the spiral phases of the two-dimensional Hubbard model using a generalized random-phase approximation. Already for small doping the spin-wave excitations are strongly renormalized due to low-energy particle-hole excitations. Besides the three Goldstone modes of the spiral state the dynamical susceptibility reveals an extra zero mode for low doping and strong coupling values signaling an intrinsic instability of the homogeneous spiral state. In addition, near-zero modes are found in the vicinity of the spiral pitch wave number for out-of-plane spin fluctuations. Their origin is found to be the near degeneracy with staggered noncoplanar spiral states which, however, are not the lowest energy Hartree-Fock solutions among the homogeneous spiral states. copyright 1996 The American Physical Society

  3. Analisa Kekuatan Spiral Bevel Gear Dengan Variasi Sudut Spiral Menggunakan Metode Elemen Hingga

    OpenAIRE

    Deta Rachmat Andika; Agus Sigit Pramono

    2017-01-01

    Seiring perkembangan zaman,  teknologi roda gigi dituntut untuk mampu mentransmisikan daya yang besar dengan efisiensi yang besar pula. Pada jenis intersecting shaft gear, tipe roda gigi payung spiral (spiral bevel gear)  merupakan perkembangan dari roda gigi payung bergigi lurus (straight bevel gear). Kelebihan dari spiral bevel gear antara  lain adalah kemampuan transmisi daya dan efisiensi yang lebih besar pada geometri yang sama serta tidak terlalu berisik. Akan tetapi spiral bevel gear j...

  4. Solvable model of spiral wave chimeras.

    Science.gov (United States)

    Martens, Erik A; Laing, Carlo R; Strogatz, Steven H

    2010-01-29

    Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core.

  5. Evolutionary Acquisition and Spiral Development Tutorial

    National Research Council Canada - National Science Library

    Hantos, P

    2005-01-01

    .... NSS Acquisition Policy 03-01 provided some space-oriented customization and, similarly to the original DOD directives, also positioned Evolutionary Acquisition and Spiral Development as preferred...

  6. Solvable Model of Spiral Wave Chimeras

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Laing, Carlo R.; Strogatz, Steven H.

    2010-01-01

    Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral...... can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core....

  7. Monotron and azimuthally corrugated: application to the high power microwaves generation

    International Nuclear Information System (INIS)

    Castro, Pedro Jose de

    2003-01-01

    The present document reports the activity of construction and initial operation of 6.7 GHz operation for high power microwave generation, the study on cylindrical resonators with azimuthally corrugated cross section, the determination of electrical conductivity of metallic materials and development of dielectric resonators for telecommunication applications

  8. Hydraulic and thermal behaviour of a corrugated plane canal. Application to plate-based heat exchangers

    International Nuclear Information System (INIS)

    Amblard, Alain

    1986-01-01

    As corrugations are often used in heat exchangers in order to promote heat exchange mechanisms through a reduction of boundary layer thickness, an increase of turbulence within the boundary layer, and an increase of exchange surface, the objectives of this research thesis are, on the one hand, to determine the influence of corrugation geometry on heat exchange and friction laws, and, on the other hand, to develop a computing software to describe the flow and heat exchange in the elementary canal. This study is limited to the case of single-phase forced convection in water. After a bibliographical overview on the hydraulic and thermal behaviour of corrugated surfaces used in heat exchangers, the author presents the different studied geometries, and the experimental installation used to determine the friction and exchange coefficient in a vertical duct formed by two corrugated plates. Experimental results are presented and compared with respect to the shape of exchange surfaces. The author then reports the use of two-dimensional code used to describe the flow in an exchanger duct [fr

  9. Quantifying wave propagation over a corrugated metal using 5 dBi antennas

    CSIR Research Space (South Africa)

    Nkosi, MC

    2015-09-01

    Full Text Available corrugated metal of a shipping container and also in a free space. The free space measurement is used as a reference point to study the influence of the metal on the wave propagation. The transmission coefficient measured over the shipping container...

  10. Design of Ultra-Wideband Tapered Slot Antenna by Using Binomial Transformer with Corrugation

    Science.gov (United States)

    Chareonsiri, Yosita; Thaiwirot, Wanwisa; Akkaraekthalin, Prayoot

    2017-05-01

    In this paper, the tapered slot antenna (TSA) with corrugation is proposed for UWB applications. The multi-section binomial transformer is used to design taper profile of the proposed TSA that does not involve using time consuming optimization. A step-by-step procedure for synthesis of the step impedance values related with step slot widths of taper profile is presented. The smooth taper can be achieved by fitting the smoothing curve to the entire step slot. The design of TSA based on this method yields results with a quite flat gain and wide impedance bandwidth covering UWB spectrum from 3.1 GHz to 10.6 GHz. To further improve the radiation characteristics, the corrugation is added on the both edges of the proposed TSA. The effects of different corrugation shapes on the improvement of antenna gain and front-to-back ratio (F-to-B ratio) are investigated. To demonstrate the validity of the design, the prototypes of TSA without and with corrugation are fabricated and measured. The results show good agreement between simulation and measurement.

  11. Evaluation of Steel Shear Walls Behavior with Sinusoidal and Trapezoidal Corrugated Plates

    Directory of Open Access Journals (Sweden)

    Emad Hosseinpour

    2015-01-01

    Full Text Available Reinforcement of structures aims to control the input energy of unnatural and natural forces. In the past four decades, steel shear walls are utilized in huge constructions in some seismic countries such as Japan, United States, and Canada to lessen the risk of destructive forces. The steel shear walls are divided into two types: unstiffened and stiffened. In the former, a series of plates (sinusoidal and trapezoidal corrugated with light thickness are used that have the postbuckling field property under overall buckling. In the latter, steel profile belt series are employed as stiffeners with different arrangement: horizontal, vertical, or diagonal in one side or both sides of wall. In the unstiffened walls, increasing the thickness causes an increase in the wall capacity under large forces in tall structures. In the stiffened walls, joining the stiffeners to the wall is costly and time consuming. The ANSYS software was used to analyze the different models of unstiffened one-story steel walls with sinusoidal and trapezoidal corrugated plates under lateral load. The obtained results demonstrated that, in the walls with the same dimensions, the trapezoidal corrugated plates showed higher ductility and ultimate bearing compared to the sinusoidal corrugated plates.

  12. Measurement with corrugated tubes of early-age autogenous shrinkage of cement-based material

    DEFF Research Database (Denmark)

    Tian, Qian; Jensen, Ole Mejlhede

    2009-01-01

    The use of a special corrugated mould enables transformation of volume strain into horizontal, linear strain measurement in the fluid stage. This allows continuous measurement of the autogenous shrinkage of cement-based materials since casting, and also effectively eliminates unwanted influence...

  13. Design and Realization Aspects of 1-THz Cascade Backward Wave Amplifier Based on Double Corrugated Waveguide

    DEFF Research Database (Denmark)

    Paoloni, Claudio; Di Carlo, Aldo; Bouamrane, Fayçal

    2013-01-01

    The design and fabrication challenges in the first ever attempt to realize a 1-THz vacuum tube amplifier are described. Implementation of innovative solutions including a slow-wave structure in the form of a double corrugated waveguide, lateral tapered input and output couplers, deep X-ray LIGA f...

  14. Self-standing corrugated Ag and Au-nanorods for plasmonic applications

    DEFF Research Database (Denmark)

    Habouti, S.; Mátéfi-Tempfli, M.; Solterbeck, C.-H.

    2011-01-01

    We use home-made Si-supported anodized alumina thin film templates for the electrodeposition of large area self-standing Ag- and Au-nanorod (Au-NR) arrays. The deposition conditions chosen, i.e. electrolyte composition and deposition voltage, lead to a corrugated rod morphology, particularly for Au...

  15. Squeezing Molecularly thin Lubricant Films between curved Corrugated Surfaces with long range Elasticity

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    2010-01-01

    3H8, C4H10, C8H18, C9H20, C10H22, C14H30 and C16H34, confined between corrugated gold surfaces. Well defined molecular layers develop in the lubricant film when the width is of the order of a few atomic diameters. An external squeezing pressure induces discontinuous, thermally activated changes...

  16. Corrugation in the nitrogen-graphite potential probed by inelastic neutron scattering

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Frank, V. L. P.; Taub, H.

    1990-01-01

    -center energy gap of ∼0.4 THz in the acoustic-phonon branches is a factor of 2 larger than calculated from central atom-atom potentials. We conclude that current models of the corrugation in the adatom substrate potential greatly underestimate the lateral restoring forces in this relatively simple molecular...

  17. Spiral 2 the scientific objectives

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-06-15

    The French ministry of research took the decision to build Spiral-2 in May 2005. Its construction costs are estimated to 130 million euros while its operating costs will near 8.5 million euros per year. The construction works will last 5 years. The Spiral-2 facility is based on a high power, superconducting driver Linac, which will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equal to 3 and energy up to 14.5 MeV/nucleon. Using a carbon converter, fast neutrons from the breakup of the 5 mA of deuterons impinging on a uranium carbide target will induce a rate of up to 10{sup 14} fissions/s. The radioactive ion beam intensities in the mass range from A = 60 to 140 will be of the order of 10{sup 6} to 10{sup 11} particles/s surpassing by one or two orders-of-magnitude any existing facility in the world. A direct irradiation of the UC{sub 2} target with {sup 3,4}He, {sup 6,7}Li or {sup 12}C may also be used. Different production targets will be used to produce high-intensity beams of light radioactive species with the Isol technique. The extracted radioactive ion beam will be accelerated to energies up to 20 MeV/nucleons by the existing Cime cyclotron. One of the most important features of the future Ganil accelerator complex will be the capability of delivering up to 5 stable or radioactive beams simultaneously in the energy range from the keV to several tens of MeV/nucleons. The document details also the future contribution of Spiral-2 concerning the structure of exotic nuclei, the thermodynamical aspects of nuclear matter, nucleosynthesis, the fundamental basic interactions, and the use of neutrons. (A.C.)

  18. Spiral 2 the scientific objectives

    International Nuclear Information System (INIS)

    2006-06-01

    The French ministry of research took the decision to build Spiral-2 in May 2005. Its construction costs are estimated to 130 million euros while its operating costs will near 8.5 million euros per year. The construction works will last 5 years. The Spiral-2 facility is based on a high power, superconducting driver Linac, which will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equal to 3 and energy up to 14.5 MeV/nucleon. Using a carbon converter, fast neutrons from the breakup of the 5 mA of deuterons impinging on a uranium carbide target will induce a rate of up to 10 14 fissions/s. The radioactive ion beam intensities in the mass range from A = 60 to 140 will be of the order of 10 6 to 10 11 particles/s surpassing by one or two orders-of-magnitude any existing facility in the world. A direct irradiation of the UC 2 target with 3,4 He, 6,7 Li or 12 C may also be used. Different production targets will be used to produce high-intensity beams of light radioactive species with the Isol technique. The extracted radioactive ion beam will be accelerated to energies up to 20 MeV/nucleons by the existing Cime cyclotron. One of the most important features of the future Ganil accelerator complex will be the capability of delivering up to 5 stable or radioactive beams simultaneously in the energy range from the keV to several tens of MeV/nucleons. The document details also the future contribution of Spiral-2 concerning the structure of exotic nuclei, the thermodynamical aspects of nuclear matter, nucleosynthesis, the fundamental basic interactions, and the use of neutrons. (A.C.)

  19. The rotation of spiral galaxies.

    Science.gov (United States)

    Rubin, V C

    1983-06-24

    There is accumulating evidence that as much as 90 percent of the mass of the universe is nonluminous and is clumped, halo-like, around individual galaxies. The gravitational force of this dark matter is presumed to be responsible for the high rotational velocities of stars and gas in the disks of spiral galaxie. At present, the form of the dark matter is unknown. Possible candidates span a range in mass of 10(70), from non-zero-mass neutrinos to massive black holes.

  20. Numerical study on the flow and heat transfer characteristics of slush nitrogen in a corrugated pipe

    Science.gov (United States)

    Li, Y. J.; Wu, S. Q.; Jin, T.

    2017-12-01

    Slush nitrogen has lower temperature, higher density and higher heat capacity than that of liquid nitrogen at normal boiling point. It is considered to be a potential coolant for high-temperature superconductive cables (HTS) that would decrease nitrogen consumption and storage cost. The corrugated pipe can help with the enhancement of heat transfer and flexibility of the coolants for HTS cables. In this paper, a 3-D Euler-Euler two-fluid model has been developed to study the flow and heat transfer characteristics of slush nitrogen in a horizontal helically corrugated pipe. By comparing with the empirical formula for pressure drop, the numerical model is confirmed to be effective for the prediction of slush nitrogen flow in corrugated pipes. The flow and heat transfer characteristics of slush nitrogen in a horizontal pipe at various working conditions (inlet solid fraction of 0-20%, inlet velocity of 0-3 m/s, heat flux of 0-12 kW/m2) have been analyzed. The friction factor of slush nitrogen is lower than that of subcooled liquid nitrogen when the slush Reynolds number is higher than 4.2×104. Moreover, the heat transfer coefficient of slush nitrogen flow in the corrugated pipe is higher than that of subcooled liquid nitrogen at velocities which is higher than that 1.76 m/s, 0.91 m/s and 0.55 m/s for slush nitrogen with solid fraction of 5%, 10% and 20%, respectively. The slush nitrogen has been confirmed to have better heat transfer performance and lower pressure drop instead of using liquid nitrogen flowing through a helically corrugated pipe.

  1. Spiral density waves in M81. I. Stellar spiral density waves

    International Nuclear Information System (INIS)

    Feng, Chien-Chang; Lin, Lien-Hsuan; Wang, Hsiang-Hsu; Taam, Ronald E.

    2014-01-01

    Aside from the grand-design stellar spirals appearing in the disk of M81, a pair of stellar spiral arms situated well inside the bright bulge of M81 has been recently discovered by Kendall et al. The seemingly unrelated pairs of spirals pose a challenge to the theory of spiral density waves. To address this problem, we have constructed a three-component model for M81, including the contributions from a stellar disk, a bulge, and a dark matter halo subject to observational constraints. Given this basic state for M81, a modal approach is applied to search for the discrete unstable spiral modes that may provide an understanding for the existence of both spiral arms. It is found that the apparently separated inner and outer spirals can be interpreted as a single trailing spiral mode. In particular, these spirals share the same pattern speed 25.5 km s –1 kpc –1 with a corotation radius of 9.03 kpc. In addition to the good agreement between the calculated and the observed spiral pattern, the variation of the spiral amplitude can also be naturally reproduced.

  2. QS Spiral: Visualizing Periodic Quantified Self Data

    DEFF Research Database (Denmark)

    Larsen, Jakob Eg; Cuttone, Andrea; Jørgensen, Sune Lehmann

    2013-01-01

    In this paper we propose an interactive visualization technique QS Spiral that aims to capture the periodic properties of quantified self data and let the user explore those recurring patterns. The approach is based on time-series data visualized as a spiral structure. The interactivity includes ...

  3. Spiral modes in cold cylindrical systems

    International Nuclear Information System (INIS)

    Robe, H.

    1975-01-01

    The linearized hydrodynamical equations governing the non-axisymmetric free modes of oscillation of cold cylindrical stellar systems are separated in cylindrical coordinates and solved numerically for two models. Short-wavelength unstable modes corresponding to tight spirals do not exist; but there exists an unstable growing mode which has the form of trailing spirals which are quite open. (orig.) [de

  4. Spiral groove seal. [for rotating shaft

    Science.gov (United States)

    Ludwig, L. P.; Strom, T. N. (Inventor)

    1974-01-01

    Mating flat surfaces inhibit leakage of a fluid around a stationary shaft. A spiral groove produces a pumping action toward the fluid when the shaft rotates. This prevents leakage while a generated hydraulic lifting force separates the mating surfaces to minimize wear. Provision is made for placing these spiral grooves in communication with the fluid to accelerate the generation of the hydraulic lifting force.

  5. ANGULAR-MOMENTUM IN BINARY SPIRAL GALAXIES

    NARCIS (Netherlands)

    OOSTERLOO, T

    In order to investigate the relative orientations of spiral galaxies in pairs, the distribution of the angle between the spin-vectors for a new sample of 40 binary spiral galaxies is determined. From this distribution it is found, contrary to an earlier result obtained by Helou (1984), that there is

  6. Colours and morphology of spiral galaxies

    International Nuclear Information System (INIS)

    Wyse, R.F.G.

    1981-01-01

    Tinsley has proposed that late-type spirals have relatively more non-luminous material than early-type spirals. A re-examination of the data indicates that this proposal is equally consistent with dark matter being more dominant in barred galaxies than in unbarred galaxies. Neither conclusion can be firm, since the dataset is far from ideal. (author)

  7. Scaling effects in spiral capsule robots.

    Science.gov (United States)

    Liang, Liang; Hu, Rong; Chen, Bai; Tang, Yong; Xu, Yan

    2017-04-01

    Spiral capsule robots can be applied to human gastrointestinal tracts and blood vessels. Because of significant variations in the sizes of the inner diameters of the intestines as well as blood vessels, this research has been unable to meet the requirements for medical applications. By applying the fluid dynamic equations, using the computational fluid dynamics method, to a robot axial length ranging from 10 -5 to 10 -2  m, the operational performance indicators (axial driving force, load torque, and maximum fluid pressure on the pipe wall) of the spiral capsule robot and the fluid turbulent intensity around the robot spiral surfaces was numerically calculated in a straight rigid pipe filled with fluid. The reasonableness and validity of the calculation method adopted in this study were verified by the consistency of the calculated values by the computational fluid dynamics method and the experimental values from a relevant literature. The results show that the greater the fluid turbulent intensity, the greater the impact of the fluid turbulence on the driving performance of the spiral capsule robot and the higher the energy consumption of the robot. For the same level of size of the robot, the axial driving force, the load torque, and the maximum fluid pressure on the pipe wall of the outer spiral robot were larger than those of the inner spiral robot. For different requirements of the operating environment, we can choose a certain kind of spiral capsule robot. This study provides a theoretical foundation for spiral capsule robots.

  8. Improved reconstruction for IDEAL spiral CSI

    DEFF Research Database (Denmark)

    Hansen, Rie Beck; Mariager, Christian; Laustsen, Christoffer

    2017-01-01

    In this study we demonstrate how reconstruction for IDEAL spiral CSI (spectroscopic imaging scheme developed for hyperpolarized dynamic metabolic MR imaging) can be improved by using regularization with a sparsity constraint. By exploiting sparsity of the spectral domain, IDEAL spiral CSI can...

  9. Research on a 170 GHz, 2 MW coaxial cavity gyrotron with inner-outer corrugation

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Shenyong, E-mail: houshenyong@sohu.com [Yangtze Normal University, Chongqing, 408001 (China); Yu, Sheng; Li, Hongfu [University of Electronics Science and Technology of China, Chengdu 610054 (China)

    2015-03-15

    In this paper, a coaxial cavity gyrotron with inner-outer corrugation is researched. The electron kineto-equations and the first order transmission line equations of the gyrotron are derived from Lorentz force equation and the transmission line theory, respectively. And then, a 2 MW, 170 GHz coaxial cavity gyrotron with inner-outer corrugation is designed. By means of numerical calculation, the beam-wave interaction of the coaxial cavity gyrotron with inner-outer corrugation is investigated. Results show that the efficient and the outpower of the gyrotron are 42.3% and 2.38 MW, respectively.

  10. Mass of the spirals galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Maupome, L; Pismis, P; Aguilar, L [Universidad Nacional Autonoma de Mexico, Mexico City. Inst. de Astronomia

    1981-01-01

    In an earlier paper we have found that the total mass of galaxies-especially of the spirals-based on values published until 1975, decreased as the Hubble type varied from Sa through Sc and Irregulars. It was also pointed out that masses determined from the hydrogen 21-cm line were higher than the optically determined masses. To investigate the cause of these tendencies we have estimated the masses using an analytic rotation curve of Brandt adjusted to the optical observations in order to include all the mass of a galaxy up to the last observed point. Although the masses computed in this manner were found to be larger, as expected, the decrease of mass with Hubble type found earlier is confirmed. However, there is a discrepancy in the earlier types (Sa, Sab) in that their radio-masses are smaller than the optically determined ones. At present, the cause of this is not clear.

  11. Effects of die profile on grain refinement in Al–Mg alloy processed by repetitive corrugation and straightening

    Energy Technology Data Exchange (ETDEWEB)

    Thangapandian, N., E-mail: erpandian@gmail.com [Department of Mechanical Engineering, College of Engineering Guindy, Anna University, Chennai 600025 (India); Balasivanandha Prabu, S. [Department of Mechanical Engineering, College of Engineering Guindy, Anna University, Chennai 600025 (India); Padmanabhan, K.A. [Centre for Nanotechnology, University of Hyderabad, Hyderabad 500046 (India)

    2016-01-01

    It is shown that a proper selection of corrugation die profile and die parameters is essential for achieving homogeneous grain refinement in materials subjected to repetitive corrugation and straightening (RCS). An Al–Mg (AA 5083) alloy was subjected to the RCS process using three different corrugation die profiles (V-groove, Flat groove, and Semi-circular groove), followed by straightening to determine the allowable maximum number of passes prior to surface cracking/fracture. Mechanical properties, i.e., hardness and tensile strength of the RCS samples were measured and compared as functions of corrugation die profiles and number of passes and the changes in microstructure. Grain refinement was studied using Electron Back Scattered Diffraction (EBSD) analysis and Transmission Electron Microscopy (TEM).

  12. IMRT delivery verification using a spiral phantom

    International Nuclear Information System (INIS)

    Richardson, Susan L.; Tome, Wolfgang A.; Orton, Nigel P.; McNutt, Todd R.; Paliwal, Bhudatt R.

    2003-01-01

    In this paper we report on the testing and verification of a system for IMRT delivery quality assurance that uses a cylindrical solid water phantom with a spiral trajectory for radiographic film placement. This spiral film technique provides more complete dosimetric verification of the entire IMRT treatment than perpendicular film methods, since it samples a three-dimensional dose subspace rather than using measurements at only one or two depths. As an example, the complete analysis of the predicted and measured spiral films is described for an intracranial IMRT treatment case. The results of this analysis are compared to those of a single field perpendicular film technique that is typically used for IMRT QA. The comparison demonstrates that both methods result in a dosimetric error within a clinical tolerance of 5%, however the spiral phantom QA technique provides a more complete dosimetric verification while being less time consuming. To independently verify the dosimetry obtained with the spiral film, the same IMRT treatment was delivered to a similar phantom in which LiF thermoluminescent dosimeters were arranged along the spiral trajectory. The maximum difference between the predicted and measured TLD data for the 1.8 Gy fraction was 0.06 Gy for a TLD located in a high dose gradient region. This further validates the ability of the spiral phantom QA process to accurately verify delivery of an IMRT plan

  13. Shear evaluation of tapered bridge girder panels with steel corrugated webs near the supports of continuous bridges

    OpenAIRE

    Zevallos, E.; Hassanein, M.F.; Real Saladrigas, Esther; Mirambell Arrizabalaga, Enrique

    2016-01-01

    Because of public construction budgets were cut over the last few years, new bridge girders with corrugated webs to reduce the construction costs have become more widely studied and used. In spite that tapered bridge girders with corrugated webs (BGCWs) are used in modern bridges, their shear strength and behaviour rarely exists in literature. Based on available literature, the web of the linearly tapered BGCWs may be divided into three typologies with different structural response to shear f...

  14. Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

    Energy Technology Data Exchange (ETDEWEB)

    Qingbang, Han; Ling, Chen; Changping, Zhu [Changzhou Key Laboratory of Sensor Networks and Environmental Sensing, College of IOT, Hohai University Changzhou, Jiangsu, 213022 (China)

    2014-02-18

    The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain, the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency.

  15. Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

    International Nuclear Information System (INIS)

    Qingbang, Han; Ling, Chen; Changping, Zhu

    2014-01-01

    The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain, the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency

  16. A technology to improve formability for aluminum alloy thin-wall corrugated sheet component hydroforming

    Directory of Open Access Journals (Sweden)

    Lang Lihui

    2015-01-01

    Full Text Available The explosively forming projectile (EFP had been traditional adopted for the aluminum thin-walled corrugated sheet, whose deformation range is large but the formability is poor, and this process usually has problems of poor surface quality, long manufacturing cycle and high cost. The active hydroforming process was suggested to solve these issues during EFP. A new technology named as blank bulging by turning the upside down active hydroforming technology was proposed to overcome difficulties in non-uniform thickness distribution and cracking failure of corrugated sheet during the conventional hydroforming process. Both numerical simulations and experiments were conducted for this new technology. The result show that the deformation capacity of aluminum alloys can be improved effectively, and the more uniform distribution of wall thickness was obtained by this new method. It is conducted that the new method is universal for thin-walled, shallow drawing parts with complex section.

  17. Impact of substrate corrugation on the sliding friction levels of adsorbed films.

    Science.gov (United States)

    Coffey, T; Krim, J

    2005-08-12

    We report a quartz crystal microbalance (QCM) study of sliding friction for solid xenon monolayers at 77 K on Cu(111), Ni(111), graphene/Ni(111), and C(60) substrates. Simulations have predicted a strong dependence of phononic friction coefficient (eta) on surface corrugation in systems with similar lattice spacing, eta approximately U(2)(0), but this has never before been shown experimentally. In order to make direct comparisons with theory, substrates with similar lattice spacing but varying amplitudes of surface corrugation were studied. QCM data reveal friction levels proportional to U(2)(0), validating current theoretical and numerical predictions. Measurements of Xe/C(60) are also included for comparison purposes.

  18. Stark effect of excitons in corrugated lateral surface superlattices: effect of centre-of-mass quantization

    International Nuclear Information System (INIS)

    Hong Sun

    1998-11-01

    The quantum confined Stark effect (QCSE) of excitons in GaAs/AlAs corrugated lateral surface superlattices (CLSSLs) is calculated. Blue and red shifts in the exciton energies are predicted for the heavy- and light-excitons in the CLSSLs, respectively, comparing with those in the unmodulated quantum well due to the different effective hole masses in the parallel direction. Sensitive dependence of the QCSE on the hole effective mass in the parallel direction is expected because of the ''centre-of-mass'' quantization (CMQ) induced by the periodic corrugated interfaces of the CLSSLs. The effect of the CMQ on the exciton mini-bands and the localization of the excitons in the CLSSLs is discussed. (author)

  19. SELF-TRAPPING OF DISKOSEISMIC CORRUGATION MODES IN NEUTRON STAR SPACETIMES

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, David [Center for Theory and Computation, Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Pappas, George [Department of Physics and Astronomy, The University of Mississippi, University, MS 38677 (United States)

    2016-02-10

    We examine the effects of higher-order multipole contributions of rotating neutron star (NS) spacetimes on the propagation of corrugation (c-)modes within a thin accretion disk. We find that the Lense–Thirring precession frequency, which determines the propagation region of the low-frequency fundamental corrugation modes, can experience a turnover allowing for c-modes to become self-trapped for sufficiently high dimensionless spin j and quadrupole rotational deformability α. If such self-trapping c-modes can be detected, e.g., through phase-resolved spectroscopy of the iron line for a high-spin low-mass accreting neutron star, this could potentially constrain the spin-induced NS quadrupole and the NS equation of state.

  20. Self-Trapping of Diskoseismic Corrugation Modes in Neutron Star Spacetimes

    Science.gov (United States)

    Tsang, David; Pappas, George

    2016-02-01

    We examine the effects of higher-order multipole contributions of rotating neutron star (NS) spacetimes on the propagation of corrugation (c-)modes within a thin accretion disk. We find that the Lense-Thirring precession frequency, which determines the propagation region of the low-frequency fundamental corrugation modes, can experience a turnover allowing for c-modes to become self-trapped for sufficiently high dimensionless spin j and quadrupole rotational deformability α. If such self-trapping c-modes can be detected, e.g., through phase-resolved spectroscopy of the iron line for a high-spin low-mass accreting neutron star, this could potentially constrain the spin-induced NS quadrupole and the NS equation of state.

  1. Corrugated structure insertion for extending the SASE bandwidth up to 3% at the European XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Zagorodnov, I.; Feng, G.; Limberg, T.

    2016-07-15

    The usage of X-ray free electron laser (XFEL) in femtosecond nanocrystallography involves sequential illumination of many small crystals of arbitrary orientation. Hence a wide radiation bandwidth will be useful in order to obtain and to index a larger number of Bragg peaks used for determination of the crystal orientation. Considering the baseline configuration of the European XFEL in Hamburg, and based on beam dynamics simulations, we demonstrate here that the usage of corrugated structures allows for a considerable increase in radiation bandwidth. Data collection with a 3% bandwidth, a few microjoule radiation pulse energy, a few femtosecond pulse duration, and a photon energy of 5.4 keV is possible. For this study we have developed an analytical modal representation of the short-range wake function of the flat corrugated structures for arbitrary offsets of the source and the witness particles.

  2. Two-phase flow patterns in adiabatic and diabatic corrugated plate gaps

    Science.gov (United States)

    Polzin, A.-E.; Kabelac, S.; de Vries, B.

    2016-09-01

    Correlations for two-phase heat transfer and pressure drop can be improved considerably, when they are adapted to specific flow patterns. As plate heat exchangers find increasing application as evaporators and condensers, there is a need for flow pattern maps for corrugated plate gaps. This contribution presents experimental results on flow pattern investigations for such a plate heat exchanger background, using an adiabatic visualisation setup as well as a diabatic setup. Three characteristic flow patterns were observed in the considered range of two-phase flow: bubbly flow, film flow and slug flow. The occurrence of these flow patterns is a function of mass flux, void fraction, fluid properties and plate geometry. Two different plate geometries having a corrugation angle of 27° and 63°, respectively and two different fluids (water/air and R365mfc liquid/vapor) have been analysed. A flow pattern map using the momentum flux is presented.

  3. Corrugated structure insertion for extending the SASE bandwidth up to 3% at the European XFEL

    International Nuclear Information System (INIS)

    Zagorodnov, I.; Feng, G.; Limberg, T.

    2016-07-01

    The usage of X-ray free electron laser (XFEL) in femtosecond nanocrystallography involves sequential illumination of many small crystals of arbitrary orientation. Hence a wide radiation bandwidth will be useful in order to obtain and to index a larger number of Bragg peaks used for determination of the crystal orientation. Considering the baseline configuration of the European XFEL in Hamburg, and based on beam dynamics simulations, we demonstrate here that the usage of corrugated structures allows for a considerable increase in radiation bandwidth. Data collection with a 3% bandwidth, a few microjoule radiation pulse energy, a few femtosecond pulse duration, and a photon energy of 5.4 keV is possible. For this study we have developed an analytical modal representation of the short-range wake function of the flat corrugated structures for arbitrary offsets of the source and the witness particles.

  4. Coupled-Mode Theory for Complex-Index, Corrugated Multilayer Stacks

    DEFF Research Database (Denmark)

    Lüder, Hannes; Gerken, Martina; Adam, Jost

    , and by choosing a bi-orthogonal basis, obtained by solving the corresponding adjoint problem. With the once found modal solutions of the unperturbed waveguide, we can calculate the coupling coefficients, which describe the mode coupling caused by the introduced periodic corrugation. [1] C. Kluge et al., Opt......We present a coupled-mode theory (CMT) approach for modelling the modal behaviour of multi- layer thinfilm devices with complex material parameters and periodic corrugations. Our method provides fast computation and extended physical insight as compared to standard numerical methods...... to be non-Hermitian, introducing two major consequences. First, the eigenvalues (i. e. the mode neff) have to be found in the complex plane (Fig. 2). Second, the classical mode orthogonality is no longer valid. We address both challenges by a combination of three complex-root solving algorithms...

  5. Lamb wave band gaps in one-dimensional radial phononic crystal plates with periodic double-sided corrugations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yinggang [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, 710049 (China); School of Transportation, Wuhan University of Technology, Wuhan 430070 (China); Chen, Tianning [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, 710049 (China); Wang, Xiaopeng, E-mail: xpwang@mail.xjtu.edu.cn [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, 710049 (China); Li, Suobin [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, 710049 (China)

    2015-11-01

    In this paper, we present the theoretical investigation of Lamb wave propagation in one-dimensional radial phononic crystal (RPC) plates with periodic double-sided corrugations. The dispersion relations, the power transmission spectra, and the displacement fields of the eigenmodes are studied by using the finite element method based on two-dimensional axial symmetry models in cylindrical coordinates. Numerical results show that the proposed RPC plates with periodic double-sided corrugations can yield several band gaps with a variable bandwidth for Lamb waves. The formation mechanism of band gaps in the double-sided RPC plates is attributed to the coupling between the Lamb modes and the in-phase and out-phases resonant eigenmodes of the double-sided corrugations. We investigate the evolution of band gaps in the double-sided RPC plates with the corrugation heights on both sides arranged from an asymmetrical distribution to a symmetrical distribution gradually. Significantly, with the introduction of symmetric double-sided corrugations, the antisymmetric Lamb mode is suppressed by the in-phase resonant eigenmodes of the double-sided corrugations, resulting in the disappearance of the lowest band gap. Furthermore, the effects of the geometrical parameters on the band gaps are further explored numerically.

  6. Variable stiffness corrugated composite structure with shape memory polymer for morphing skin applications

    Science.gov (United States)

    Gong, Xiaobo; Liu, Liwu; Scarpa, Fabrizio; Leng, Jinsong; Liu, Yanju

    2017-03-01

    This work presents a variable stiffness corrugated structure based on a shape memory polymer (SMP) composite with corrugated laminates as reinforcement that shows smooth aerodynamic surface, extreme mechanical anisotropy and variable stiffness for potential morphing skin applications. The smart composite corrugated structure shows a low in-plane stiffness to minimize the actuation energy, but also possess high out-of-plane stiffness to transfer the aerodynamic pressure load. The skin provides an external smooth aerodynamic surface because of the one-sided filling with the SMP. Due to variable stiffness of the shape memory polymer the morphing skin exhibits a variable stiffness with a change of temperature, which can help the skin adjust its stiffness according different service environments and also lock the temporary shape without external force. Analytical models related to the transverse and bending stiffness are derived and validated using finite element techniques. The stiffness of the morphing skin is further investigated by performing a parametric analysis against the geometry of the corrugation and various sets of SMP fillers. The theoretical and numerical models show a good agreement and demonstrate the potential of this morphing skin concept for morphing aircraft applications. We also perform a feasibility study of the use of this morphing skin in a variable camber morphing wing baseline. The results show that the morphing skin concept exhibits sufficient bending stiffness to withstand the aerodynamic load at low speed (less than 0.3 Ma), while demonstrating a large transverse stiffness variation (up to 191 times) that helps to create a maximum mechanical efficiency of the structure under varying external conditions.

  7. Uses of four-fold coaxial corrugated piping in low temperature technology

    Energy Technology Data Exchange (ETDEWEB)

    Beck, A; Rohner, P [Kabel- und Metallwerke Gutehoffnungshuette A.G., Hannover (Germany, F.R.)

    1978-06-01

    The increasing uses of superconducting equipment in various areas of research and technology, including even medicine, create an increasing demand for suitable transfer lines for liquid helium which still remains practically the only suitable coolant. This paper reports on flexible four-fold coaxial corrugated piping lines which can combine a forword flow and a return flow channel for the coolant and which can be designed for various operating conditions. The mechanical and thermal properties of such piping lines are discussed.

  8. Measuring the height-to-height correlation function of corrugation in suspended graphene

    International Nuclear Information System (INIS)

    Kirilenko, D.A.; Brunkov, P.N.

    2016-01-01

    Nanocorrugation of 2D crystals is an important phenomenon since it affects their electronic and mechanical properties. The corrugation may have various sources; one of them is flexural phonons that, in particular, are responsible for the thermal conductivity of graphene. A study of corrugation of just the suspended graphene can reveal much of valuable information on the physics of this complicated phenomenon. At the same time, the suspended crystal nanorelief can hardly be measured directly because of high flexibility of the 2D crystal. Moreover, the relief portion related to rapid out-of-plane oscillations (flexural phonons) is also inaccessible by such measurements. Here we present a technique for measuring the Fourier components of the height–height correlation function H(q) of suspended graphene which includes the effect of flexural phonons. The technique is based on the analysis of electron diffraction patterns. The H(q) is measured in the range of wavevectors q≈0.4–4.5 nm"−"1. At the upper limit of this range H(q) does follow the T/κq"4 law. So, we measured the value of suspended graphene bending rigidity κ=1.2±0.4 eV at ambient temperature T≈300 K. At intermediate wave vectors, H(q) follows a slightly weaker exponent than theoretically predicted q"−"3"."1"5 but is closer to the results of the molecular dynamics simulation. At low wave vectors, the dependence becomes even weaker, which may be a sign of influence of charge carriers on the dynamics of undulations longer than 10 nm. The technique presented can be used for studying physics of flexural phonons in other 2D materials. - Highlights: • A technique for measuring free-standing 2D crystal corrugation is proposed. • The height-to-height correlation function of the suspended graphene corrugation is measured. • Various parameters of the intrinsic graphene properties are experimentally determined.

  9. Psychometric properties of startle and corrugator response in NPU, affective picture viewing, and resting state tasks.

    Science.gov (United States)

    Kaye, Jesse T; Bradford, Daniel E; Curtin, John J

    2016-08-01

    The current study provides a comprehensive evaluation of critical psychometric properties of commonly used psychophysiology laboratory tasks/measures within the NIMH RDoC. Participants (N = 128) completed the no-shock, predictable shock, unpredictable shock (NPU) task, affective picture viewing task, and resting state task at two study visits separated by 1 week. We examined potentiation/modulation scores in NPU (predictable or unpredictable shock vs. no-shock) and affective picture viewing tasks (pleasant or unpleasant vs. neutral pictures) for startle and corrugator responses with two commonly used quantification methods. We quantified startle potentiation/modulation scores with raw and standardized responses. We quantified corrugator potentiation/modulation in the time and frequency domains. We quantified general startle reactivity in the resting state task as the mean raw startle response during the task. For these three tasks, two measures, and two quantification methods, we evaluated effect size robustness and stability, internal consistency (i.e., split-half reliability), and 1-week temporal stability. The psychometric properties of startle potentiation in the NPU task were good, but concerns were noted for corrugator potentiation in this task. Some concerns also were noted for the psychometric properties of both startle and corrugator modulation in the affective picture viewing task, in particular, for pleasant picture modulation. Psychometric properties of general startle reactivity in the resting state task were good. Some salient differences in the psychometric properties of the NPU and affective picture viewing tasks were observed within and across quantification methods. © 2016 The Authors. Psychophysiology published by Wiley Periodicals, Inc. on behalf of Society for Psychophysiological Research.

  10. Evaluation of Thermo-Fluid Performance of Compact Heat Exchanger with Corrugated Wall Channels

    International Nuclear Information System (INIS)

    Tak, Nam Il; Lee, Won Jae

    2006-01-01

    One of the key components of an indirect nuclear hydrogen production system is an intermediate heat exchanger (IHX). For the IHX, a printed circuit heat exchanger (PCHE) is known as one of the promising types due to its compactness and ability to operate at high temperatures and under high pressures. The PCHE is a relatively new heat exchanger. It has been commercially manufactured only since 1985 and solely by one British vendor, HeatricTM. Due to its short history and limited production, sufficient information about the PCHE is not available for the design of the IHX in open literatures. The predominant shape of flow channels of the PCHE is laterally corrugated. The flow in a corrugated wall channel is very interesting since a variety of flow phenomena can be considered by changing the amplitude-to-wavelength ratio. In the present paper, thermo-fluid performance of a heat exchanger with a typical PCHE geometry has been evaluated. Computational fluid dynamics (CFD) analysis was performed to analyze a gas flow behavior in a corrugated wall channel

  11. Flow Regimes of Air-Water Counterflow Through Cross Corrugated Parallel Plates

    Energy Technology Data Exchange (ETDEWEB)

    de Almeida, V.F.

    2000-06-07

    Heretofore unknown flow regimes of air-water counterflow through a pair of transparent vertical parallel cross corrugated plates were observed via high-speed video. Air flows upward driven by pressure gradient and water, downward driven by gravity. The crimp geometry of the corrugations was drawn from typical corrugated sheets used as filling material in modern structured packed towers. Four regimes were featured, namely, rivulet, bicontinuous, flooding fronts, and flooding waves. It is conceivable that the regimes observed might constitute the basis for understanding how gas and liquid phases contend for available space in the interstices of structured packings in packed towers. Flow regime transitions were expressed in terms of liquid load (liquid superficial velocity) and gas flow factor parameters commonly used in pressure drop and capacity curves. We have carefully examined the range of parameters equivalent to the ill-understood high-liquid-flow operation in packed towers. More importantly, our findings should prove valuable in validating improved first-principles modeling of gas-liquid flows in these industrially important devices.

  12. Improvement of formability for fabricating thin continuously corrugated structures in sheet metal forming process

    International Nuclear Information System (INIS)

    Choi, Sung Woo; Park, Sang Hu; Park, Seong Hun; Ha, Man Yeong; Jeong, Ho Seung; Cho, Jong Rae

    2012-01-01

    A stamping process is widely used for fabricating various sheet metal parts for vehicles, airplanes, and electronic devices by the merit of low processing cost and high productivity. Recently, the use of thin sheets with a corrugated structure for sheet metal parts has rapidly increased for use in energy management devices, such as heat exchangers, separators in fuel cells, and many others. However, it is not easy to make thin corrugated structures directly using a single step stamping process due to their geometrical complexity and very thin thickness. To solve this problem, a multi step stamping (MSS) process that includes a heat treatment process to improve formability is proposed in this work: the sequential process is the initial stamping, heat treatment, and final shaping. By the proposed method, we achieved successful results in fabricating thin corrugated structures with an average thickness of 75μm and increased formability of about 31% compared to the single step stamping process. Such structures can be used in a plate-type heat exchanger requiring low weight and a compact shape

  13. Corrugation Architecture Enabled Ultraflexible Wafer-Scale High-Efficiency Monocrystalline Silicon Solar Cell

    KAUST Repository

    Bahabry, Rabab R.

    2018-01-02

    Advanced classes of modern application require new generation of versatile solar cells showcasing extreme mechanical resilience, large-scale, low cost, and excellent power conversion efficiency. Conventional crystalline silicon-based solar cells offer one of the most highly efficient power sources, but a key challenge remains to attain mechanical resilience while preserving electrical performance. A complementary metal oxide semiconductor-based integration strategy where corrugation architecture enables ultraflexible and low-cost solar cell modules from bulk monocrystalline large-scale (127 × 127 cm) silicon solar wafers with a 17% power conversion efficiency. This periodic corrugated array benefits from an interchangeable solar cell segmentation scheme which preserves the active silicon thickness of 240 μm and achieves flexibility via interdigitated back contacts. These cells can reversibly withstand high mechanical stress and can be deformed to zigzag and bifacial modules. These corrugation silicon-based solar cells offer ultraflexibility with high stability over 1000 bending cycles including convex and concave bending to broaden the application spectrum. Finally, the smallest bending radius of curvature lower than 140 μm of the back contacts is shown that carries the solar cells segments.

  14. Soda-Anthraquinone Durian (Durio Zibethinus Murr.) Rind Linerboard and Corrugated Medium Paper: A Preliminary Test

    Science.gov (United States)

    Rizal Masrol, Shaiful; Irwan Ibrahim, Mohd Halim; Adnan, Sharmiza; Mubarak Sa'adon, Amir; Ika Sukarno, Khairil; Fadrol Hisham Yusoff, Mohd

    2017-08-01

    A preliminary test was conducted to investigate the characteristics of linerboard and corrugated medium paper made from durian rind waste. Naturally dried durian rinds were pulped according to Soda-Anthraquinone (Soda-AQ) pulping process with a condition of 20% active alkali, 0.1% AQ, 7:1 liquor to material ratio, 120 minutes cooking time and 170°C cooking temperature. The linerboard and corrugated medium paper with a basis weight of 120 gsm were prepared and evaluated according to Malaysian International Organization for Standardization (MS ISO) and Technical Association of the Pulp and Paper Industry (TAPPI). The results indicate that the characteristics of durian rind linerboard are comparable with other wood or non-wood based paper and current commercial paper. However, low CMT value for corrugated medium and water absorptiveness quality for linerboard could be improved in future. Based on the bulk density (0.672 g/cm3), burst index (3.12 kPa.m2/g) and RCT (2.00 N.m2/g), the durian rind has shown a good potential and suitable as an alternative raw material source for linerboard industry.

  15. Corrugation Architecture Enabled Ultraflexible Wafer-Scale High-Efficiency Monocrystalline Silicon Solar Cell

    KAUST Repository

    Bahabry, Rabab R.; Kutbee, Arwa T.; Khan, Sherjeel M.; Sepulveda, Adrian C.; Wicaksono, Irmandy; Nour, Maha A.; Wehbe, Nimer; Almislem, Amani Saleh Saad; Ghoneim, Mohamed T.; Sevilla, Galo T.; Syed, Ahad; Shaikh, Sohail F.; Hussain, Muhammad Mustafa

    2018-01-01

    Advanced classes of modern application require new generation of versatile solar cells showcasing extreme mechanical resilience, large-scale, low cost, and excellent power conversion efficiency. Conventional crystalline silicon-based solar cells offer one of the most highly efficient power sources, but a key challenge remains to attain mechanical resilience while preserving electrical performance. A complementary metal oxide semiconductor-based integration strategy where corrugation architecture enables ultraflexible and low-cost solar cell modules from bulk monocrystalline large-scale (127 × 127 cm) silicon solar wafers with a 17% power conversion efficiency. This periodic corrugated array benefits from an interchangeable solar cell segmentation scheme which preserves the active silicon thickness of 240 μm and achieves flexibility via interdigitated back contacts. These cells can reversibly withstand high mechanical stress and can be deformed to zigzag and bifacial modules. These corrugation silicon-based solar cells offer ultraflexibility with high stability over 1000 bending cycles including convex and concave bending to broaden the application spectrum. Finally, the smallest bending radius of curvature lower than 140 μm of the back contacts is shown that carries the solar cells segments.

  16. Compact Elliptically Tapered Slot Antenna with Non-uniform Corrugations for Ultra-wideband Applications

    Directory of Open Access Journals (Sweden)

    F. G. Zhu

    2013-04-01

    Full Text Available A small size elliptically tapered slot antenna (ETSA fed by coplanar waveguide (CPW for ultra-wideband (UWB applications is proposed. It is printed on an FR4 substrate and occupies a size of 37×34×0.8 mm^3. A pair of quarter circular shapes is etched on the radiator to reduce the size. To overcome the limitation of uniform corrugation, non-uniform corrugation is utilized to reduce the cross-polarization level. A parametric study is carried out to investigate the effects of circular cut and corrugations. In order to validate the design, a prototype is fabricated and measured. Both simulated and measured results confirm that the proposed antenna achieves a good performance of a reflection coefficient below -10 dB from 3.1 GHz to 10.6 GHz, including a maximum antenna gain of 8.1dBi, directional patterns in the end-fire direction, low cross-polarization level below -20 dB and linear phase response. The antenna is promising for applications in UWB impulse radar imaging.

  17. Echo-Interleaved-Spiral MR Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Rosenthal, Shirrie; Azhari, Haim [Department of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa 32000 (Israel); Montag, Avram [Elscint Ltd., MRI division, Haifa (Israel)

    1999-12-31

    Interleaved-Spiral imaging is an efficient method for MRI fast scans. However, images suffer from blurring and artifacts due to field inhomogeneities and the long readout times. In this paper, we combine interleaved-spirals with spin-echo for 3D scans. The refocusing RF-pulses (echoes) refocus off-resonance spins, thus allowing longer acquisition times per excitation, by limiting inhomogeneity effects. The total number of excitations for a 3D scan is reduced by half. The 3D Fourier transform of an object is divided into pairs of slices, one slice is scanned in an outgoing interleaved-spiral, initiated after a 90 degree pulse has been applied. The second slice is scanned in an ingoing interleaved-spiral, after a 180 degree pulse has been applied, thus reaching the slice origin at the echo time. (authors) 4 refs., 3 figs.

  18. Echo-Interleaved-Spiral MR Imaging

    International Nuclear Information System (INIS)

    Rosenthal, Shirrie; Azhari, Haim; Montag, Avram

    1998-01-01

    Interleaved-Spiral imaging is an efficient method for MRI fast scans. However, images suffer from blurring and artifacts due to field inhomogeneities and the long readout times. In this paper, we combine interleaved-spirals with spin-echo for 3D scans. The refocusing RF-pulses (echoes) refocus off-resonance spins, thus allowing longer acquisition times per excitation, by limiting inhomogeneity effects. The total number of excitations for a 3D scan is reduced by half. The 3D Fourier transform of an object is divided into pairs of slices, one slice is scanned in an outgoing interleaved-spiral, initiated after a 90 degree pulse has been applied. The second slice is scanned in an ingoing interleaved-spiral, after a 180 degree pulse has been applied, thus reaching the slice origin at the echo time. (authors)

  19. Pulsatile spiral blood flow through arterial stenosis.

    Science.gov (United States)

    Linge, Fabian; Hye, Md Abdul; Paul, Manosh C

    2014-11-01

    Pulsatile spiral blood flow in a modelled three-dimensional arterial stenosis, with a 75% cross-sectional area reduction, is investigated by using numerical fluid dynamics. Two-equation k-ω model is used for the simulation of the transitional flow with Reynolds numbers 500 and 1000. It is found that the spiral component increases the static pressure in the vessel during the deceleration phase of the flow pulse. In addition, the spiral component reduces the turbulence intensity and wall shear stress found in the post-stenosis region of the vessel in the early stages of the flow pulse. Hence, the findings agree with the results of Stonebridge et al. (2004). In addition, the results of the effects of a spiral component on time-varying flow are presented and discussed along with the relevant pathological issues.

  20. Magnetic spiral arms in galaxy haloes

    Science.gov (United States)

    Henriksen, R. N.

    2017-08-01

    We seek the conditions for a steady mean field galactic dynamo. The parameter set is reduced to those appearing in the α2 and α/ω dynamo, namely velocity amplitudes, and the ratio of sub-scale helicity to diffusivity. The parameters can be allowed to vary on conical spirals. We analyse the mean field dynamo equations in terms of scale invariant logarithmic spiral modes and special exact solutions. Compatible scale invariant gravitational spiral arms are introduced and illustrated in an appendix, but the detailed dynamical interaction with the magnetic field is left for another work. As a result of planar magnetic spirals `lifting' into the halo, multiple sign changes in average rotation measures forming a regular pattern on each side of the galactic minor axis, are predicted. Such changes have recently been detected in the Continuum Halos in Nearby Galaxies-an EVLA Survey (CHANG-ES) survey.

  1. Statistical analysis of metallicity in spiral galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Galeotti, P [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Turin Univ. (Italy). Ist. di Fisica Generale)

    1981-04-01

    A principal component analysis of metallicity and other integral properties of 33 spiral galaxies is presented; the involved parameters are: morphological type, diameter, luminosity and metallicity. From the statistical analysis it is concluded that the sample has only two significant dimensions and additonal tests, involving different parameters, show similar results. Thus it seems that only type and luminosity are independent variables, being the other integral properties of spiral galaxies correlated with them.

  2. Galactic models with variable spiral structure

    International Nuclear Information System (INIS)

    James, R.A.; Sellwood, J.A.

    1978-01-01

    A series of three-dimensional computer simulations of disc galaxies has been run in which the self-consistent potential of the disc stars is supplemented by that arising from a small uniform Population II sphere. The models show variable spiral structure, which is more pronounced for thin discs. In addition, the thin discs form weak bars. In one case variable spiral structure associated with this bar has been seen. The relaxed discs are cool outside resonance regions. (author)

  3. SIGNATURES OF LONG-LIVED SPIRAL PATTERNS

    International Nuclear Information System (INIS)

    Martínez-García, Eric E.; González-Lópezlira, Rosa A.

    2013-01-01

    Azimuthal age/color gradients across spiral arms are a signature of long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where we have previously found azimuthal age/color gradient candidates, 13 objects were further selected if a two-armed grand-design pattern survived in a surface density stellar mass map. Mass maps were obtained from optical and near-infrared imaging, by comparison with a Monte Carlo library of stellar population synthesis models that allowed us to obtain the mass-to-light ratio in the J band, (M/L) J , as a function of (g – i) versus (i – J) color. The selected spirals were analyzed with Fourier methods in search of other signatures of long-lived modes related to the gradients, such as the gradient divergence toward corotation, and the behavior of the phase angle of the two-armed spiral in different wavebands, as expected from theory. The results show additional signatures of long-lived spirals in at least 50% of the objects.

  4. Chiralities of spiral waves and their transitions.

    Science.gov (United States)

    Pan, Jun-ting; Cai, Mei-chun; Li, Bing-wei; Zhang, Hong

    2013-06-01

    The chiralities of spiral waves usually refer to their rotation directions (the turning orientations of the spiral temporal movements as time elapses) and their curl directions (the winding orientations of the spiral spatial geometrical structures themselves). Traditionally, they are the same as each other. Namely, they are both clockwise or both counterclockwise. Moreover, the chiralities are determined by the topological charges of spiral waves, and thus they are conserved quantities. After the inwardly propagating spirals were experimentally observed, the relationship between the chiralities and the one between the chiralities and the topological charges are no longer preserved. The chiralities thus become more complex than ever before. As a result, there is now a desire to further study them. In this paper, the chiralities and their transition properties for all kinds of spiral waves are systemically studied in the framework of the complex Ginzburg-Landau equation, and the general relationships both between the chiralities and between the chiralities and the topological charges are obtained. The investigation of some other models, such as the FitzHugh-Nagumo model, the nonuniform Oregonator model, the modified standard model, etc., is also discussed for comparison.

  5. Spiral 2: preliminary design study

    International Nuclear Information System (INIS)

    2001-11-01

    The scientific council of GANIL asked to perform a comparative study on the production methods based on gamma induced fission and rapid-neutron induced fission concerning the nature and the intensity of the neutron-rich products. The production rate expected should be around 10 13 fissions per second. The study should include the implantation and the costs of the concerned accelerators. The scientific committee recommended also to study the possibility to re-inject the radioactive beams of SPIRAL-II in the cyclotrons available at GANIL in order to give access to an energy range from 1.7 to 100 MeV/nucleon. For that purpose, some study groups have been formed to evaluate the possibility of such a project in the different components: physics case, target-ion sources, drivers, post-acceleration and general infrastructure. The organization of the project study is given at the end of this report. The following report presents an overview of the study. Particularly the total costs have been assessed according to 3 options for the driver: 38.0*10 6 euros for a 40 MeV deuteron linac, 18.7*10 6 euros for a 45 MeV electron linac, and 29.1*10 6 euros for a 80 MeV deuteron cyclotron

  6. Spiral 2: preliminary design study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-11-15

    The scientific council of GANIL asked to perform a comparative study on the production methods based on gamma induced fission and rapid-neutron induced fission concerning the nature and the intensity of the neutron-rich products. The production rate expected should be around 10{sup 13} fissions per second. The study should include the implantation and the costs of the concerned accelerators. The scientific committee recommended also to study the possibility to re-inject the radioactive beams of SPIRAL-II in the cyclotrons available at GANIL in order to give access to an energy range from 1.7 to 100 MeV/nucleon. For that purpose, some study groups have been formed to evaluate the possibility of such a project in the different components: physics case, target-ion sources, drivers, post-acceleration and general infrastructure. The organization of the project study is given at the end of this report. The following report presents an overview of the study. Particularly the total costs have been assessed according to 3 options for the driver: 38.0*10{sup 6} euros for a 40 MeV deuteron linac, 18.7*10{sup 6} euros for a 45 MeV electron linac, and 29.1*10{sup 6} euros for a 80 MeV deuteron cyclotron.

  7. Dark matter in spiral galaxies

    International Nuclear Information System (INIS)

    Albada, T.S. van; Sancisi, R.

    1986-01-01

    Mass models of spiral galaxies based on the observed light distribution, assuming constant M/L for bulge and disc, are able to reproduce the observed rotation curves in the inner regions, but fail to do so increasingly towards and beyond the edge of the visible material. The discrepancy in the outer region can be accounted for by invoking dark matter; some galaxies require at least four times as much dark matter as luminous matter. There is no evidence for a dependence on galaxy luminosity or morphological type. Various arguments support the idea that a distribution of visible matter with constant M/L is responsible for the circular velocity in the inner region, i.e. inside approximately 2.5 disc scalelengths. Luminous matter and dark matter seem to 'conspire' to produce the flat observed rotation curves in the outer region. It seems unlikely that this coupling between disc and halo results from the large-scale gravitational interaction between the two components. Attempts to determine the shape of dark halos have not yet produced convincing results. (author)

  8. Modeling and experimental study of a corrugated wick type solar still: Comparative study with a simple basin type

    International Nuclear Information System (INIS)

    Matrawy, K.K.; Alosaimy, A.S.; Mahrous, A.-F.

    2015-01-01

    Highlights: • Performance of corrugated wick type solar still is compared with simple type. • Corrugated porous surface contributes by about 75% of the total productivity. • Productivity of corrugated solar still was 34% more than that for simple type. - Abstract: In the present work, the productivity of a solar still is modified by forming the evaporative surface as a corrugated shape as well as by decreasing the heat capacity with the use of a porous material. This target has been achieved by using black clothes in a corrugated shape that are immersed in water where the clothes absorbs water and get saturated by capillary effect. Along with the proposed corrugated wick type solar still, a simple basin still type was fabricated and tested to compare the enhancement accomplished by the developed solar still. Inclined reflectors were used to augment the solar radiation incident on the plane of the developed solar stills. The energy balance in the developed mathematical models takes into consideration the glass covers, the porous material, along with the portion of water exposed to the transmitted solar radiation as well as the portion of water shaded by the corrugated surface. The developed mathematical model was validated by fabricating and testing two models for the proposed and simple basin solar stills under the same conditions. Good agreement between the simulated and experimental results has been detected. It has been found that an improvement of about 34% in the productivity for the proposed wick type solar still is gained as compared to the simple basin case. Also, the best tilt angle for the inclined reflector has been found to be about 30° with respect to the vertical direction of the setup under consideration.

  9. Six Decades of Spiral Density Wave Theory

    Science.gov (United States)

    Shu, Frank H.

    2016-09-01

    The theory of spiral density waves had its origin approximately six decades ago in an attempt to reconcile the winding dilemma of material spiral arms in flattened disk galaxies. We begin with the earliest calculations of linear and nonlinear spiral density waves in disk galaxies, in which the hypothesis of quasi-stationary spiral structure (QSSS) plays a central role. The earliest success was the prediction of the nonlinear compression of the interstellar medium and its embedded magnetic field; the earliest failure, seemingly, was not detecting color gradients associated with the migration of OB stars whose formation is triggered downstream from the spiral shock front. We give the reasons for this apparent failure with an update on the current status of the problem of OB star formation, including its relationship to the feathering substructure of galactic spiral arms. Infrared images can show two-armed, grand design spirals, even when the optical and UV images show flocculent structures. We suggest how the nonlinear response of the interstellar gas, coupled with overlapping subharmonic resonances, might introduce chaotic behavior in the dynamics of the interstellar medium and Population I objects, even though the underlying forces to which they are subject are regular. We then move to a discussion of resonantly forced spiral density waves in a planetary ring and their relationship to the ideas of disk truncation, and the shepherding of narrow rings by satellites orbiting nearby. The back reaction of the rings on the satellites led to the prediction of planet migration in protoplanetary disks, which has had widespread application in the exploding data sets concerning hot Jupiters and extrasolar planetary systems. We then return to the issue of global normal modes in the stellar disk of spiral galaxies and its relationship to the QSSS hypothesis, where the central theoretical concepts involve waves with negative and positive surface densities of energy and angular

  10. Ditches and Drainage Structures, Culverts - cross drains were collected using a GPS for drainage basin project. Ditches are planned for the future., Published in 2005, 1:2400 (1in=200ft) scale, Effingham County Government.

    Data.gov (United States)

    NSGIC Local Govt | GIS Inventory — Ditches and Drainage Structures dataset current as of 2005. Culverts - cross drains were collected using a GPS for drainage basin project. Ditches are planned for...

  11. Multi-objective shape optimization of double pipe heat exchanger with inner corrugated tube using RSM method

    International Nuclear Information System (INIS)

    Han, Huai-Zhi; Li, Bing-Xi; Wu, Hao; Shao, Wei

    2015-01-01

    Integrated a fully developing three-dimensional heat transfer and flow model, a multi-objective optimization aims to fulfill the geometric design for double-tube heat exchangers with inner corrugated tube is investigated in this work with RSM. Dimensionless corrugation pitch (p/D), dimensionless corrugation height (H/D), dimensionless corrugation radius (r/D) and Reynolds number (Re) are considered as four design parameters. Considering the process parameters, the characteristic numbers involving heat transfer characteristic, resistance characteristic and overall heat transfer performance calculated by CFD, and are served as objective functions to the RSM (Nu c , f c , Nu c /Nu s , f c /f s and h in this paper). The results of optimal designs are a set of multiple optimum solutions, called 'Pareto optimal solutions'. It reveals the identical tendency of Nu c /Nu s and f c /f s reflecting the conflict between them that means augmenting the heat transfer performance with various design parameters in the optimal situation inevitably sacrificed the increase of flow resistance. According to the Pareto optimal curves, the optimum designing parameters of double pipe heat exchanger with inner corrugated tube under the constrains of Nu c /Nu s ≥1.2 are found to be P/D = 0.82, H/D = 0.22, r/D = 0.23, Re = 26,263, corresponding to the maximum value of η = 1.12. (authors)

  12. Investigation of logarithmic spiral nanoantennas at optical frequencies

    Science.gov (United States)

    Verma, Anamika; Pandey, Awanish; Mishra, Vigyanshu; Singh, Ten; Alam, Aftab; Dinesh Kumar, V.

    2013-12-01

    The first study is reported of a logarithmic spiral antenna in the optical frequency range. Using the finite integration technique, we investigated the spectral and radiation properties of a logarithmic spiral nanoantenna and a complementary structure made of thin gold film. A comparison is made with results for an Archimedean spiral nanoantenna. Such nanoantennas can exhibit broadband behavior that is independent of polarization. Two prominent features of logarithmic spiral nanoantennas are highly directional far field emission and perfectly circularly polarized radiation when excited by a linearly polarized source. The logarithmic spiral nanoantenna promises potential advantages over Archimedean spirals and could be harnessed for several applications in nanophotonics and allied areas.

  13. Galaxy Zoo: dust in spiral galaxies

    Science.gov (United States)

    Masters, Karen L.; Nichol, Robert; Bamford, Steven; Mosleh, Moein; Lintott, Chris J.; Andreescu, Dan; Edmondson, Edward M.; Keel, William C.; Murray, Phil; Raddick, M. Jordan; Schawinski, Kevin; Slosar, Anže; Szalay, Alexander S.; Thomas, Daniel; Vandenberg, Jan

    2010-05-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination dependence of optical colours for 24276 well-resolved Sloan Digital Sky Survey (SDSS) galaxies visually classified via the Galaxy Zoo project. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4mag for the ugri passbands (estimating 0.3mag of extinction in z band). We split the sample into `bulgy' (early-type) and `discy' (late-type) spirals using the SDSS fracdeV (or fDeV) parameter and show that the average face-on colour of `bulgy' spirals is redder than the average edge-on colour of `discy' spirals. This shows that the observed optical colour of a spiral galaxy is determined almost equally by the spiral type (via the bulge-disc ratio and stellar populations), and reddening due to dust. We find that both luminosity and spiral type affect the total amount of extinction, with discy spirals at Mr ~ -21.5mag having the most reddening - more than twice as much as both the lowest luminosity and most massive, bulge-dominated spirals. An increase in dust content is well known for more luminous galaxies, but the decrease of the trend for the most luminous has not been observed before and may be related to their lower levels of recent star formation. We compare our results with the latest dust attenuation models of Tuffs et al. We find that the model reproduces the observed trends reasonably well but overpredicts the amount of u-band attenuation in edge-on galaxies. This could be an inadequacy in the Milky Way extinction law (when applied to external galaxies), but more likely indicates the need for a wider range of dust-star geometries. We end by discussing the effects of dust on large galaxy surveys and emphasize that these effects will become important as we push to higher precision measurements of galaxy properties and their clustering. This publication has been made possible by the participation of more than

  14. Analysis of spiral components in 16 galaxies

    International Nuclear Information System (INIS)

    Considere, S.; Athanassoula, E.

    1988-01-01

    A Fourier analysis of the intensity distributions in the plane of 16 spiral galaxies of morphological types from 1 to 7 is performed. The galaxies processed are NGC 300,598,628,2403,2841,3031,3198,3344,5033,5055,5194,5247,6946,7096,7217, and 7331. The method, mathematically based upon a decomposition of a distribution into a superposition of individual logarithmic spiral components, is first used to determine for each galaxy the position angle PA and the inclination ω of the galaxy plane onto the sky plane. Our results, in good agreement with those issued from different usual methods in the literature, are discussed. The decomposition of the deprojected galaxies into individual spiral components reveals that the two-armed component is everywhere dominant. Our pitch angles are then compared to the previously published ones and their quality is checked by drawing each individual logarithmic spiral on the actual deprojected galaxy images. Finally, the surface intensities for angular periodicities of interest are calculated. A choice of a few of the most important ones is used to elaborate a composite image well representing the main spiral features observed in the deprojected galaxies

  15. Improving indoor air quality by using the new generation of corrugated cardboard-based filters.

    Science.gov (United States)

    Candiani, Gabriele; Del Curto, Barbara; Cigada, Alberto

    2012-09-27

    Indoor Air Quality (IAQ) is strictly affected by the concentration of total suspended particulate matter (TSP). Air filtration is by far the most feasible suggestion to improve IAQ. Unfortunately, highly effective HEPA filters also have a few major weaknesses that have hindered their widespread use. There is therefore a renewed interest in developing novel, cost-effective filtration systems. We have recently reported the development of cardboard-based filters for bacterial removal that were further implemented and tested herein. A parallelepiped filter manufactured by aligning strips of corrugated cardboard and surrounded by a cardboard frame was specifically designed with an internal pocket holding a partially cut antistatic pleated fabric (HP). This filter, together with its parent version (CTRL) and a commercially sourced specimen (CAF), were assessed comparatively in a long-time test to assess their effectiveness on TSP removal. We found that the TSP abatement efficiency (E%) of the HP filter was relatively high and invariable over the 93 days of test and the pressure drop (PD%) decrease because of filter clogging was moderate. Most important, the HP filter was the most effective if assessed in terms of overall yield (Y%) and its performance was quite constant over the entire period considered. This work disclosed this novel class of corrugated cardboard-based filters as promising tools to ameliorate IAQ in light of their good TSP removal properties that endure over time. Moreover, cardboard is a lightweight, inexpensive, and eco-friendly material and corrugated cardboard-based air filters are very easy to shape and mount on and/or replace in existing ventilation systems.

  16. Spoof surface plasmon modes on doubly corrugated metal surfaces at terahertz frequencies

    International Nuclear Information System (INIS)

    Liu, Yong-Qiang; Kong, Ling-Bao; Du, Chao-Hai; Liu, Pu-Kun

    2016-01-01

    Spoof surface plasmons (SSPs) have many potential applications such as imaging and sensing, communications, innovative leaky wave antenna and many other passive devices in the microwave and terahertz (THz) spectrum. The extraordinary properties of SSPs (e.g. extremely strong near field, enhanced beam–wave interaction) make them especially attractive for developing novel THz electronic sources. SSP modes on doubly corrugated metal surfaces are investigated and analyzed both theoretically and numerically in this paper. The analytical SSP dispersion expressions of symmetric and anti-symmetric modes are obtained with a simplified modal field expansion method; the results are also verified by the finite integration method. Additionally, the propagation losses are also considered for real copper surfaces with a limited constant conductivity in a THz regime. It is shown that the asymptotical frequency of the symmetric mode at the Brillouin boundary decreases along with the decreased gap size between these two corrugated metal surfaces while the asymptotical frequency increases for the anti-symmetric mode. The anti-symmetric mode demonstrates larger propagation losses than the symmetric mode. Further, the losses for both symmetric and anti-symmetric modes decrease when this gap size enlarges. By decreasing groove depth, the asymptotical frequency increases for both the symmetric and the anti-symmetric mode, but the variation of propagation losses is more complicated. Propagation losses increase along with the increased period. Our studies on the dispersion characteristics and propagation losses of SSP modes on this doubly corrugated metallic structure with various parameters is instructive for numerous applications such as waveguides, circuitry systems with high integration, filters and powerful electronic sources in the THz regime. (paper)

  17. Long-Term Performance of Primary and Secondary Electroactive Biofilms Using Layered Corrugated Carbon Electrodes

    International Nuclear Information System (INIS)

    Baudler, André; Riedl, Sebastian; Schröder, Uwe

    2014-01-01

    The performance of primary and secondary electroactive biofilms grown on layered corrugated carbon (LCC) electrodes was studied over a period of several months. With an average projected current density of 6.7 mA cm −2 , the studied secondary electroactive biofilms outperformed the primary biofilms (3.0 mA cm −2 ) over the entire experimental period. At the same time, both, primary and secondary biofilms, exhibited a constant Coulomb efficiency of about 89%. The study further illustrates that three-dimensional electrodes such as LCC allow a sustained long-term performance without significant decrease in electrode performance.

  18. Ohmic losses in coaxial resonators with longitudinal inner-outer corrugation

    Energy Technology Data Exchange (ETDEWEB)

    Shenyong Hou, A. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Yangtze Normal University, Chongqing 408001 (China); Sheng Yu, B.; Hongfu Li, C.; Qixiang Zhao, D. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Xiang Li, E. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Queen Mary University of London, London E1 4NS (United Kingdom)

    2013-05-15

    In this paper, a coaxial resonator with longitudinal inner-outer corrugation is introduced. Its eigen-equation and expression of ohmic losses are derived. Ohmic losses in the cavity are investigated. Results show that ohmic losses in the outer and inner conductors share a similar variation trend, while the former is larger than the later. What's more, changes of the inner and outer slot depth and width induce different variations of ohmic losses on the surface of the inner and outer conductors.

  19. Thermal-Hydraulic Performance of a Corrugated Cooling Fin with Louvered Surfaces

    DEFF Research Database (Denmark)

    Sønderby, Simon Kaltoft; Hosseini, Seyed Mojtaba Mir; Rezaniakolaei, Alireza

    2017-01-01

    The main objective of the article is to investigate thermal-hydraulic performance of a corrugated cooling fin with louvered surfaces. The investigation is carried out using the fin geometry of one most commonly used liquid-to-air heat exchangers. The investigation was carried out by numerically...... simulating the airflow with louvered fin geometry. The simulation model was verified by comparing simulated j- and f-factors with the corresponding values of several experimental correlations. The j-factors deviated less than 10.7 % from two of the experimental correlations, whereas deviations ranging...

  20. Theory and Monte-Carlo simulation of adsorbates on corrugated surfaces

    DEFF Research Database (Denmark)

    Vives, E.; Lindgård, P.-A.

    1993-01-01

    -phase between the commensurate and incommensurate phase stabilized by defects. Special attention has been given to the study of the epitaxial rotation angles of the different phases. Available experimental data is in agreement with the simulations and with a general theory for the epitaxial rotation which takes......Phase transitions in systems of adsorbed molecules on corrugated surfaces are studied by means of Monte Carlo simulation. Particularly, we have studied the phase diagram of D2 on graphite as a function of coverage and temperature. We have demonstrated the existence of an intermediate gamma...

  1. Numerical simulation study of gas-liquid reactive mass transfer along corrugated sheets with interface tracking

    International Nuclear Information System (INIS)

    Haroun, Y.

    2008-11-01

    This work is done within the framework of gas treatment and CO 2 capture process development. The main objective of the present work is to fill the gap between classical experiments and industrial conditions by the use of Computational Fluid Dynamics (CFD). The physical problem considered corresponds to the liquid film flow down a corrugate surface under gravity in present of a gas phase. The chemical species in the gas phase absorb in the liquid phase and react. Numerical calculations are carried out in order to determine the impact of physical and geometrical properties on reactive mass transfer in industrial operating conditions. (author)

  2. Optimization of a Conical Corrugated Antenna Using Multiobjective Heuristics for Radio-Astronomy Applications

    OpenAIRE

    López-Ruiz, S.; Sánchez Montero, R.; Tercero-Martínez, F.; López-Espí, P. L.; López-Fernandez, J. A.

    2016-01-01

    This paper presents the design of a tree sections corrugated horn antenna with a modified linear profile, using NURBS, suitable for radio-astronomy applications. The operating band ranges from 4.5 to 8.8 GHz. The aperture efficiency is higher than 84% and the return losses are greater than 20 dB in the whole bandwidth. The antenna optimization has been carried out with multiobjective versions of an evolutionary algorithm (EA) and a particle swarm optimization (PSO) algorithm. We show that bot...

  3. Long-Term Performance of Primary and Secondary Electroactive Biofilms Using Layered Corrugated Carbon Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Baudler, André; Riedl, Sebastian; Schröder, Uwe, E-mail: uwe.schroeder@tu-bs.de [Institute of Environmental and Sustainable Chemistry, Technische Universität Braunschweig, Braunschweig (Germany)

    2014-07-30

    The performance of primary and secondary electroactive biofilms grown on layered corrugated carbon (LCC) electrodes was studied over a period of several months. With an average projected current density of 6.7 mA cm{sup −2}, the studied secondary electroactive biofilms outperformed the primary biofilms (3.0 mA cm{sup −2}) over the entire experimental period. At the same time, both, primary and secondary biofilms, exhibited a constant Coulomb efficiency of about 89%. The study further illustrates that three-dimensional electrodes such as LCC allow a sustained long-term performance without significant decrease in electrode performance.

  4. Analytical and Numerical Study of Foam-Filled Corrugated Core Sandwich Panels under Low Velocity Impact

    Directory of Open Access Journals (Sweden)

    Mohammad Nouri Damghani

    2016-05-01

    Full Text Available Analytical and finite element simulations are used to predict the effect of core density on the energy absorption of composite sandwich panels under low-velocity impact. The composite sandwich panel contains two facesheets and a foam-filled corrugated core. Analytical model is defined as a two degree-of-freedom system based on equivalent mass, spring, and dashpot to predict the local and global deformation response of a simply supported panel. The results signify a good agreement between analytical and numerical predictions.

  5. Dual nature of localization in guiding systems with randomly corrugated boundaries: Anderson-type versus entropic

    International Nuclear Information System (INIS)

    Tarasov, Yu.V.; Shostenko, L.D.

    2015-01-01

    A unified theory for the conductance of an infinitely long multimode quantum wire whose finite segment has randomly rough lateral boundaries is developed. It enables one to rigorously take account of all feasible mechanisms of wave scattering, both related to boundary roughness and to contacts between the wire rough section and the perfect leads within the same technical frameworks. The rough part of the conducting wire is shown to act as a mode-specific randomly modulated effective potential barrier whose height is governed essentially by the asperity slope. The mean height of the barrier, which is proportional to the average slope squared, specifies the number of conducting channels. Under relatively small asperity amplitude this number can take on arbitrary small, up to zero, values if the asperities are sufficiently sharp. The consecutive channel cut-off that arises when the asperity sharpness increases can be regarded as a kind of localization, which is not related to the disorder per se but rather is of entropic or (equivalently) geometric origin. The fluctuating part of the effective barrier results in two fundamentally different types of guided wave scattering, viz., inter- and intramode scattering. The intermode scattering is shown to be for the most part very strong except in the cases of (a) extremely smooth asperities, (b) excessively small length of the corrugated segment, and (c) the asperities sharp enough for only one conducting channel to remain in the wire. Under strong intermode scattering, a new set of conducting channels develops in the corrugated waveguide, which have the form of asymptotically decoupled extended modes subject to individual solely intramode random potentials. In view of this fact, two transport regimes only are realizable in randomly corrugated multimode waveguides, specifically, the ballistic and the localized regime, the latter characteristic of one-dimensional random systems. Two kinds of localization are thus shown to

  6. Sharp corners as sources of spiral pairs

    International Nuclear Information System (INIS)

    Biton, Y.; Rabinovitch, A.; Braunstein, D.; Friedman, M.; Aviram, I.

    2010-01-01

    It is demonstrated that using the FitzHugh-Nagumo model, stimulation of excitable media inside a region possessing sharp corners, can lead to the appearance of sources of spiral-pairs of sustained activity. The two conditions for such source creation are: The corners should be less than 120 deg. and the range of stimulating amplitudes should be small, occurring just above the threshold value and decreasing with the corner angle. The basic mechanisms driving the phenomenon are discussed. These include: A. If the corner angle is below 120 deg., the wave generated inside cannot emerge at the corner tip, resulting in the creation of two free edges which start spiraling towards each other. B. Spiraling must be strong enough; otherwise annihilation of the rotating arms would occur too soon to create a viable source. C. The intricacies of the different radii involved are elucidated. Possible applications in heart stimulation and in chemical reactions are considered.

  7. Principles of spiral CT: III. Quality assurance

    International Nuclear Information System (INIS)

    Suess, C.; Kalender, W.A.

    1998-01-01

    Since its introduction in 1989 spiral CT has gained wide clinical acceptance and meanwhile it covers a large range of CT applications. This new technology, however, has not yet been recognized and acknowledged in the national or international regulations on scanner quality assurance (QA) programs. The conventional QA procedures should be extended to check the distribution of resolution and noise within the image plane. Imaging performance in the axial direction constitutes one of the major advantages of spiral scanning. Therefore, the slice sensitivity profiles and the spatial and low-contrast resolution along the z-axis have to be assessed. The high demands on table feed accuracy require additional tests. We suggest phantoms and procedures to check and quantify these parameters. Thereby, we hope to support the ongoing discussion about spiral CT quality assurance. (orig.) [de

  8. Spiral loaded cavities for heavy ion acceleration

    International Nuclear Information System (INIS)

    Schempp, A.; Klein, H.

    1976-01-01

    A transmission line theory of the spiral resonator has been performed and the calculated and measured properties will be compared. Shunt impedances up to 50 MΩ/m have been measured. In a number of high power tests the structure has been tested and its electrical and mechanical stability has been investigated. The static frequency shift due to ponderomotoric forces was between 0.2 and 50 kHz/kW dependent on the geometrical parameters of the spirals. The maximum field strength obtained on the axis was 16 MV/m in pulsed operation and 9.2 MV/m in cw, corresponding to a voltage gain per cavity of up to 0.96 MV. The results show that spiral resonators are well suited as heavy ion accelerator cavities. (author)

  9. Organic carbon spiralling in stream ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Newbold, J D; Mulholland, P J; Elwood, J W; O' Neill, R V

    1982-01-01

    The term spiralling has been used to describe the combined processes of cycling and longitudinal transport in streams. As a measure or organic carbon spiralling, we introduced organic carbon turnover length, S, defined as the average or expected downstream distance travelled by a carbon atom between its entry or fixation in the stream and its oxidation. Using a simple model for organic carbon dynamics in a stream, we show that S is closely related to fisher and Likens' ecosystem efficiency. Unlike efficiency, however, S is independent of the length of the study reach, and values of S determined in streams of differing lengths can be compared. Using data from three different streams, we found the relationship between S and efficiency to agree closely with the model prediction. Hypotheses of stream functioning are discussed in the context of organic carbeon spiralling theory.

  10. Spiral arms, comets and terrestrial catastrophism

    International Nuclear Information System (INIS)

    Clube, S.V.M.; Napier, W.M.

    1982-01-01

    A review is presented of an hypothesis of terrestrial catastrophism in which comets grow in molecular clouds and are captured by the Sun as it passes through the spiral arms of the Galaxy. Assuming that comets are a major supplier of the Earth-crossing (Appollo) asteroid population, the latter fluctuates correspondingly and leads to episodes of terrestrial bombardment. Changes in the rotational momentum of core and mantle, generated by impacts, lead to episodes of magnetic field reversal and tectonic activity, while surface phenomena lead to ice-ages and mass extinctions. An episodic geophysical history with an interstellar connection is thus implied. If comets in spiral arms are necessary intermediaries in the process of star formation, the theory also has implications relating to early solar system history and galactic chemistry. These aspects are briefly discussed with special reference to the nature of spiral arms. (author)

  11. Considerations of an oscillating spiral universe cosmology

    International Nuclear Information System (INIS)

    Sachs, M.

    1989-01-01

    It is proposed that if the spiral configuration of galaxies is explicable in terms of the equations of motion of its constituent stars, as an expression of global laws of nature, then the universe as a whole may be similarly described in terms of the motions of its constituent galaxies with a similar spiral dynamics. With the functional form of the spiral paths in terms of Fresnel integrals, taken from solutions of equations in general relativity (from previous analyses of galactic configurations) the density of the universe at the big bang stage is determined. It is found to depend, numerically, on the neutron lifetime and the period of oscillation of the universe as a whole. There is some concluding discussion of the implications of this analysis of the matter of the universe at the big bang stage vis a vis the black hole state of matter

  12. Molecular clouds and galactic spiral structure

    International Nuclear Information System (INIS)

    Dame, T.M.

    1984-02-01

    Galactic CO line emission at 115 GHz was surveyed in order to study the distribution of molecular clouds in the inner galaxy. Comparison of this survey with similar H1 data reveals a detailed correlation with the most intense 21 cm features. To each of the classical 21 cm H1 spiral arms of the inner galaxy there corresponds a CO molecular arm which is generally more clearly defined and of higher contrast. A simple model is devised for the galactic distribution of molecular clouds. The modeling results suggest that molecular clouds are essentially transient objects, existing for 15 to 40 million years after their formation in a spiral arm, and are largely confined to spiral features about 300 pc wide

  13. Spiral CT manifestations of spherical pneumonia

    International Nuclear Information System (INIS)

    Li Xiaohong; Yang Hongwei; Xu Chunmin; Qin Xiu

    2008-01-01

    Objective: To explore the Spiral CT manifestations and differential diagnosis of spherical pneumonia. Methods: 18 cases of spherical pneumonia and 20 cases of peripheral pulmonary carcinoma were selected, both of them were confirmed by clinic and/or pathology. The SCT findings of both groups were compared retrospectively. Results: Main spiral CT findings of spherical pneumonia were showed as followings: square or triangular lesions adjacent to pleura; with irregular shape, blurry, slightly lobulated margin, sometimes with halo sign. Small inflammatory patches and intensified vascular markings around the lesions were seen. Lesions became smaller or vanished after short-term anti-inflammatory treatment. Conclusion: Spherical pneumonia showed some characteristics on Spiral CT scan, which are helpful in diagnosis and differential diagnosis of this disease. (authors)

  14. Spiral CT for evaluation of chest trauma

    International Nuclear Information System (INIS)

    Roehnert, W.; Weise, R.

    1997-01-01

    After implementation of spiral CT in our department, we carried out an analysis for determining anew the value of CT as a modality of chest trauma diagnosis in the emergency department. The retrospective study covers a period of 10 months and all emergency patients with chest trauma exmined by spiral CT. The major lesions of varying seriousness covered by this study are: pneumothorax, hematothorax, pulmonary contusion or laceration, mediastinal hematoma, rupture of a vessel, injury of the heart and pericardium. The various fractures are not included in this study. In many cases, spiral CT within relatively short time yields significant diagnostic findings, frequently saving additional angiography. A rigid diagnostic procedure cannot be formulated. Plain-film chest radiography still remains a diagnostic modality of high value. (Orig.) [de

  15. Simulations of the flocculent spiral M33: what drives the spiral structure?

    Science.gov (United States)

    Dobbs, C. L.; Pettitt, A. R.; Corbelli, E.; Pringle, J. E.

    2018-05-01

    We perform simulations of isolated galaxies in order to investigate the likely origin of the spiral structure in M33. In our models, we find that gravitational instabilities in the stars and gas are able to reproduce the observed spiral pattern and velocity field of M33, as seen in HI, and no interaction is required. We also find that the optimum models have high levels of stellar feedback which create large holes similar to those observed in M33, whilst lower levels of feedback tend to produce a large amount of small scale structure, and undisturbed long filaments of high surface density gas, hardly detected in the M33 disc. The gas component appears to have a significant role in producing the structure, so if there is little feedback, both the gas and stars organise into clear spiral arms, likely due to a lower combined Q (using gas and stars), and the ready ability of cold gas to undergo spiral shocks. By contrast models with higher feedback have weaker spiral structure, especially in the stellar component, compared to grand design galaxies. We did not see a large difference in the behaviour of Qstars with most of these models, however, because Qstars stayed relatively constant unless the disc was more strongly unstable. Our models suggest that although the stars produce some underlying spiral structure, this is relatively weak, and the gas physics has a considerable role in producing the large scale structure of the ISM in flocculent spirals.

  16. Neutrons for science (NFS) at spiral-2

    International Nuclear Information System (INIS)

    Ridikas, D.

    2005-01-01

    Both cross section measurements and various applications could be realised successfully using the high energy neutrons that will be produced at SPIRAL-2. Two particular cases were examined in more detail, namely: (a) neutron time-of-flight (nToF) measurements with pulsed neutron beams, and (b) material activation-irradiation with high-energy high-intensity neutron fluxes. Thanks to the high energy and high intensity neutron flux available, SPIRAL-2 offers a unique opportunity for material irradiations both for fission and fusion related research, tests of various detection systems and of resistance of electronics components to irradiations, etc. SPIRAL-2 also could be considered as an intermediate step towards new generation dedicated irradiation facilities as IFMIF previewed only beyond 2015. Equally, the interval from 0.1 MeV to 40 MeV for neutron cross section measurements is an energy range that is of particular importance for energy applications, notably accelerator driven systems (ADS) and Gen-IV fast reactors, as well as for fusion related devices. It is also the region where pre-equilibrium approaches are often used to link the low (evaporation) and high energy (intra-nuclear cascade) reaction models. With very intense neutron beams of SPIRAL-2 measurements of very low mass (often radioactive) targets and small cross sections become feasible in short experimental campaigns. Production of radioactive targets for dedicated physics experiments is also an attractive feature of SPIRAL-2. In brief, it was shown that SPIRAL-2 has got a remarkable potential for neutron based research both for fundamental physics and various applications. In addition, in the neutron energy range from a few MeV to, say, 35 MeV this research would have a leading position for the next 10-15 years if compared to other neutron facilities in operation or under construction worldwide. (author)

  17. Kidney spiral CT, indications, realization, results

    International Nuclear Information System (INIS)

    Braunschweig, R.; Beilicke, M.; Hundt, W.; Breiteneder, T.; Reiser, M.

    1999-01-01

    The introduction of spiral computed tomography (spiral CT) has vastly enriched the methodologically diversity of computer-tomographic scans. It allows for the recording of different perfusion or excretion stages of the kidney parenchyma of the urine draining paths by carrying out long-distance, phase-identical multiple examinations of the retroperitoneum. The description of the findings which are characterized by their local and contrasts behavior is possible. The following report describes the indications and technological process of kidney spiral CT using kidney-typical intravenous contrast media. Special emphasis is put on the advantages and limits of multiple phase spiral CT. Decisive preconditions are: 1. Specific clinical query, 2. selection of the corresponding phase contrasts of the kidneys and uretra or bladder, 3. exact technical and temporal adjustment of the acquisition parameters. Scanning times are in the range of seconds. The overall examination can be carried out quick and without any major strain on the part of the patient. A sound proof and a general differentiation of focal kideny lesions can be derived from the acquired data. This is also true for kidneys and ureters findings. Bladder findings can be localized and differentiated according to stage. More than two 'spiral acquisitions' should be carried out with restraint taking exposure to radiation into account. Due to the sound registration of focal lesions, its capability of reproduction and its short-time examination, the spiral CT of the kidneys can be said to be the most effective current scanning method of the retroperitoneum following clinical examinations and sonography. (orig.) [de

  18. Graphite target for the spiral project

    International Nuclear Information System (INIS)

    Putaux, J.C.; Ducourtieux, M.; Ferro, A.; Foury, P.; Kotfila, L.; Mueller, A.C.; Obert, J.; Pauwels, N.; Potier, J.C.; Proust, J.; Loiselet, M.

    1996-01-01

    A study of the thermal and physical properties of graphite targets for the SPIRAL project is presented. The main objective is to develop an optimized set-up both mechanically and thermally resistant, presenting good release properties (hot targets with thin slices). The results of irradiation tests concerning the mechanical and thermal resistance of the first prototype of SPIRAL target with conical geometry are presented. The micro-structural properties of the graphite target is also studied, in order to check that the release properties are not deteriorated by the irradiation. Finally, the results concerning the latest pilot target internally heated by an electrical current are shown. (author)

  19. Packing of equal discs on a parabolic spiral lattice

    International Nuclear Information System (INIS)

    Xudong, F.; Bursill, L.A.; Julin, P.

    1989-01-01

    A contact disc model is investigated to determine the most closely-packed parabolic spiral lattice. The most space-efficient packings have divergence angles in agreement with the priority ranking of natural spiral structures

  20. Inkjet printing of UHF antennas on corrugated cardboards for packaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Sowade, Enrico, E-mail: enrico.sowade@mb.tu-chemnitz.de [Digital Printing and Imaging Technology, Technische Universität Chemnitz, Chemnitz (Germany); Göthel, Frank [Digital Printing and Imaging Technology, Technische Universität Chemnitz, Chemnitz (Germany); Zichner, Ralf [Department Printed Functionalities, Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz (Germany); Baumann, Reinhard R. [Digital Printing and Imaging Technology, Technische Universität Chemnitz, Chemnitz (Germany); Department Printed Functionalities, Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz (Germany)

    2015-03-30

    Highlights: • Inkjet printing of UHF antennas on cardboard substrates. • Development of primer layer to compensate the absorptiveness of the cardboard and the rough surface. • Manufacturing of UHF antennas in a fully digital manner for packaging applications. - Abstract: In this study, a method based on inkjet printing has been established to develop UHF antennas on a corrugated cardboard for packaging applications. The use of such a standardized, paper-based packaging substrate as material for printing electronics is challenging in terms of its high surface roughness and high ink absorption rate, especially when depositing very thin films with inkjet printing technology. However, we could obtain well-defined silver layers on the cardboard substrates due to a primer layer approach. The primer layer is based on a UV-curable ink formulation and deposited as well as the silver ink with inkjet printing technology. Industrial relevant printheads were chosen for the deposition of the materials. The usage of inkjet printing allows highest flexibility in terms of pattern design. The primer layer was proven to optimize the surface characteristics of the substrate, mainly reducing the surface roughness and water absorptiveness. Thanks to the primer layer approach, ultra-high-frequency (UHF) radio-frequency identification (RFID) antennas were deposited by inkjet printing on the corrugated cardboards. Along with the characterization and interpretation of electrical properties of the established conductive antenna patterns, the performance of the printed antennas were analyzed in detail by measuring the scattering parameter S{sub 11} and the antenna gain.

  1. Numerical Simulation of Turbulent Half-corrugated Channel Flow by Hydrophilic and Hydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    M. R. Rastan

    2018-03-01

    Full Text Available In the first part of the present study, a two dimensional half-corrugated channel flow is simulated at Reynolds number of 104, in no-slip condition (hydrophilic surfaces( using various low Reynolds turbulence models as well as standard k-ε model; and an appropriate turbulence model (k-ω 1998 model( is proposed. Then, in order to evaluate the proposed solution method in simulation of flow adjacent to hydrophobic surfaces, turbulent flow is simulated in simple channel and the results are compared with the literature. Finally, two dimensional half-corrugated channel flow at Reynolds number of 104 is simulated again in vicinity of hydrophobic surfaces for varoius slip lengths. The results show that this method is capable of drag reduction in such a way that an increase of 200 μm in slip length leads to a massive drag reduction up to 38%. In addition, to access a significant drag reduction in turbulent flows, the non-dimensionalized slip length should be larger than the minimum.

  2. Performance analysis of solar air heater with jet impingement on corrugated absorber plate

    Directory of Open Access Journals (Sweden)

    Alsanossi M. Aboghrara

    2017-09-01

    Full Text Available This paper deals with the experimental investigation outlet temperature and efficiency, of Solar Air heater (SAH. The experimental test set up designed and fabricated to study the effect of jet impingement on the corrugated absorber plate, through circular jets in a duct flow of solar air heater, and compared with conventional solar air heater on flat plat absorber. Under effect of mass flow rate (ṁ of air and solar radiation on outlet air temperature, and efficiency, are analyzed. Results show the flow jet impingement on corrugated plat absorber is a strong function of heat transfer enhancement. The present investigation concludes that the mass flow rate of air substantially influences the heat transfer on solar air heaters. And the thermal efficiency of proposed design duct is observed almost 14% more as compare to the smooth duct. At solar radiation 500–1000 (W/M2, 308 K ambient temperature and 0.01–0.03 (Kg/S mass flow rate

  3. Removal of VOCs from air stream with corrugated sheet as adsorbent

    Directory of Open Access Journals (Sweden)

    Rabia Arshad

    2016-10-01

    Full Text Available A large proportional of volatile organic compounds (VOCs are released into the environment from various industrial processes. The current study elucidates an application of a simple adsorption phenomenon for removal of three main types of VOCs, i.e., benzene, xylene and toluene, from an air stream. Two kinds of adsorbents namely acid digested adsorbent and activated carbon are prepared to assess the removal efficiency of each adsorbent in the indoor workplace environment. The results illustrate that the adsorbents prepared from corrugated sheets were remarkably effective for the removal of each pollutant type. Nevertheless, activated carbon showed high potential of adsorbing the targeted VOC compared to the acid digested adsorbent. The uptake by the adsorbents was in the following order: benzene > xylene > toluene. Moreover, maximum adsorption of benzene, toluene and xylene occurred at 20 °C and 1.5 cm/s for both adsorbents whereas minimum success was attained at 30 °C and 1.0 cm/s. However, adsorption pattern are found to be similar for each of the the three aromatic hydrocarbons. It is concluded that the corrugated sheets waste can be a considered as a successful and cost-effective solution towards effective removal of targeted pollutants in the air stream.

  4. Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Goksu, E I; Nellis, B A; Lin, W; Satcher Jr., J H; Groves, J T; Risbud, S H; Longo, M L

    2008-10-30

    Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g. porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, diffusion, and lipid density in comparison to mica-supported lipid bilayers were characterized by AFM, FRAP, FCS, and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of lipids on xerogel ({approx}1.7 {micro}m{sup 2}/s) is predictably lower than on mica ({approx}4.1 {micro}m{sup 2}/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase bilayer that penetrates approximately midway into the first layer of {approx}50 nm xerogel beads.

  5. Mass transport enhancement in redox flow batteries with corrugated fluidic networks

    Science.gov (United States)

    Lisboa, Kleber Marques; Marschewski, Julian; Ebejer, Neil; Ruch, Patrick; Cotta, Renato Machado; Michel, Bruno; Poulikakos, Dimos

    2017-08-01

    We propose a facile, novel concept of mass transfer enhancement in flow batteries based on electrolyte guidance in rationally designed corrugated channel systems. The proposed fluidic networks employ periodic throttling of the flow to optimally deflect the electrolytes into the porous electrode, targeting enhancement of the electrolyte-electrode interaction. Theoretical analysis is conducted with channels in the form of trapezoidal waves, confirming and detailing the mass transport enhancement mechanism. In dilute concentration experiments with an alkaline quinone redox chemistry, a scaling of the limiting current with Re0.74 is identified, which compares favourably against the Re0.33 scaling typical of diffusion-limited laminar processes. Experimental IR-corrected polarization curves are presented for high concentration conditions, and a significant performance improvement is observed with the narrowing of the nozzles. The adverse effects of periodic throttling on the pumping power are compared with the benefits in terms of power density, and an improvement of up to 102% in net power density is obtained in comparison with the flow-by case employing straight parallel channels. The proposed novel concept of corrugated fluidic networks comes with facile fabrication and contributes to the improvement of the transport characteristics and overall performance of redox flow battery systems.

  6. Characterization of low-frequency acoustic wave propagation through a periodic corrugated waveguide

    Science.gov (United States)

    Jiang, Changyong; Huang, Lixi

    2018-03-01

    In this paper, a periodic corrugated waveguide structure is proposed, and its unit-cell is analyzed by the wave finite element method. In low-frequency range, the unit-cell is treated as an equivalent fluid through a homogenization process, and the equivalent acoustic parameters are obtained, which are validated by finite structure simulations and experiments. The proposed structure is shown to add tortuosity to the waveguide, hence higher equivalent fluid density is achieved, while the system elastic modulus remains unchanged. As a result, the equivalent speed of sound is smaller than normal air. The application of such change of speed of sound is demonstrated in the classic quarter-wavelength resonator based on the corrugated waveguide, which gives a lower resonance frequency with the same side branch length. When the waveguide is filled with porous materials, the added tortuosity enhances the broadband, low-frequency sound absorption by increasing the equivalent mass without bringing in excess damping, the latter being partly responsible for the poor performance of usual porous materials in the low-frequency region. Therefore, the proposed structure provides another dimension for the design and optimization of porous sound absorption materials.

  7. Hierarchical synthesis of corrugated photocatalytic TiO{sub 2} microsphere architectures on natural pollen surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Erdogan, Deniz Altunoz; Ozensoy, Emrah, E-mail: ozensoy@fen.bilkent.edu.tr

    2017-05-01

    Highlights: • Biotemplate-based photocatalytic material was synthesized in the form of corrugated TiO{sub 2} microspheres. • Characterization of photocatalysts as a function of temperature. • Photocatalytic activities studied in the gas and solution phases. - Abstract: Biomaterials are challenging, yet vastly promising templates for engineering unusual inorganic materials with unprecedented surface and structural properties. In the current work, a novel biotemplate-based photocatalytic material was synthesized in the form of corrugated TiO{sub 2} microspheres by utilizing a sol-gel methodology where Ambrosia trifida (Ab, Giant ragweed) pollen was exploited as the initial biological support surface. Hierarchically synthesized TiO{sub 2} microspheres were structurally characterized in detail via SEM-EDX, Raman spectroscopy, XRD and BET techniques in order to shed light on the surface chemistry, crystal structure, chemical composition and morphology of these novel material architectures. Photocatalytic functionality of the synthesized materials was demonstrated both in gas phase as well as in liquid phase. Along these lines, air and water purification capabilities of the synthesized TiO{sub 2} microspheres were established by performing photocatalytic oxidative NOx(g) storage and Rhodamine B(aq) degradation experiments; respectively. The synthetic approach presented herein offers new opportunities to design and create sophisticated functional materials that can be used in micro reactor systems, adsorbents, drug delivery systems, catalytic processes, and sensor technologies.

  8. The dynamics of the spiral galaxy M81

    International Nuclear Information System (INIS)

    Visser, H.C.D.

    1978-01-01

    A detailed comparison of the observations of the spiral galaxy M81 with the density-wave theory for tightly-wound spirals is presented. In particular, hydrogen-line observations are compared with the nonlinear density-wave theory for the gas with the aim of constructing a density-wave model for the spiral galaxy M81

  9. Adaptation of the control system in view of SPIRAL integration

    International Nuclear Information System (INIS)

    Lecorche, E.

    1998-01-01

    As soon as the collaboration between the SPIRAL project and the Control Group has been defined, the first implementation of the SPIRAL control system started following various directions. Both the global hardware and software architectures has been specified and some practical works have been undertaken such as the Ethernet network installation or the first SPIRAL oriented software design and coding. (authors)

  10. Spiral kicker for the beam abort system

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.L.

    1983-01-01

    A brief study was carried out to determine the feasibility of a special kicker to produce a damped spiral beam at the beam dump for the beam abort system. There appears to be no problem with realizing this concept at a reasonably low cost.

  11. Spiral kicker for the beam abort system

    International Nuclear Information System (INIS)

    Martin, R.L.

    1983-01-01

    A brief study was carried out to determine the feasibility of a special kicker to produce a damped spiral beam at the beam dump for the beam abort system. There appears to be no problem with realizing this concept at a reasonably low cost

  12. Irrational Numbers Can "In-Spiral" You

    Science.gov (United States)

    Lewis, Leslie D.

    2007-01-01

    This article describes the instructional process of helping students visualize irrational numbers. Students learn to create a spiral, called "the wheel of Theodorus," which demonstrates irrational and rational lengths. Examples of student work help the reader appreciate the delightful possibilities of this project. (Contains 4 figures.)

  13. Importance of packing in spiral defect chaos

    Indian Academy of Sciences (India)

    We develop two measures to characterize the geometry of patterns exhibited by the state of spiral defect chaos, a weakly turbulent regime of Rayleigh-Bénard convection. These describe the packing of contiguous stripes within the pattern by quantifying their length and nearest-neighbor distributions. The distributions ...

  14. Spiral CT-angiography of the aorta

    NARCIS (Netherlands)

    Balm, R.; Eikelboom, B. C.; van Leeuwen, M. S.; Noordzij, J.

    1994-01-01

    AIMS: To determine whether the new technique of CT-angiography was accurate in displaying the complex anatomy of the aorta and its major branches. METHODS: Seventeen patients with a variety of aortic pathology were examined. Using a spiral CT-scanner a volumetric scan was made during injection of

  15. STRUCTURED MOLECULAR GAS REVEALS GALACTIC SPIRAL ARMS

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, Tsuyoshi [Joint ALMA Office, Alonso de Cordova 3107, Vitacura, Santiago 763-0355 (Chile); Hasegawa, Tetsuo [NAOJ Chile Observatory, Joaquin Montero 3000 Oficina 702, Vitacura, Santiago 763-0409 (Chile); Koda, Jin, E-mail: sawada.tsuyoshi@nao.ac.jp [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)

    2012-11-01

    We explore the development of structures in molecular gas in the Milky Way by applying the analysis of the brightness distribution function and the brightness distribution index (BDI) in the archival data from the Boston University-Five College Radio Astronomy Observatory {sup 13}CO J = 1-0 Galactic Ring Survey. The BDI measures the fractional contribution of spatially confined bright molecular emission over faint emission extended over large areas. This relative quantity is largely independent of the amount of molecular gas and of any conventional, pre-conceived structures, such as cores, clumps, or giant molecular clouds. The structured molecular gas traced by higher BDI is located continuously along the spiral arms in the Milky Way in the longitude-velocity diagram. This clearly indicates that molecular gas changes its structure as it flows through the spiral arms. Although the high-BDI gas generally coincides with H II regions, there is also some high-BDI gas with no/little signature of ongoing star formation. These results support a possible evolutionary sequence in which unstructured, diffuse gas transforms itself into a structured state on encountering the spiral arms, followed by star formation and an eventual return to the unstructured state after the spiral arm passage.

  16. Investigation of Spiral and Sweeping Holes

    Science.gov (United States)

    Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram

    2015-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.

  17. High-displacement spiral piezoelectric actuators

    Science.gov (United States)

    Mohammadi, F.; Kholkin, A. L.; Jadidian, B.; Safari, A.

    1999-10-01

    A high-displacement piezoelectric actuator, employing spiral geometry of a curved piezoelectric strip is described. The monolithic actuators are fabricated using a layered manufacturing technique, fused deposition of ceramics, which is capable of prototyping electroceramic components with complex shapes. The spiral actuators (2-3 cm in diameter) consisted of 4-5 turns of a lead zirconate titanate ceramic strip with an effective length up to 28 cm. The width was varied from 0.9 to 1.75 mm with a height of 3 mm. When driven by the electric field applied across the width of the spiral wall, the tip of the actuator was found to displace in both radial and tangential directions. The tangential displacement of the tip was about 210 μm under the field of 5 kV/cm. Both the displacement and resonant frequency of the spirals could be tailored by changing the effective length and wall width. The blocking force of the actuator in tangential direction was about 1 N under the field of 5 kV/cm. These properties are advantageous for high-displacement low-force applications where bimorph or monomorph actuators are currently employed.

  18. Biofouling of spiral wound membrane systems

    NARCIS (Netherlands)

    Vrouwenvelder, J.S.

    2009-01-01

    Biofouling of spiral wound membrane systems High quality drinking water can be produced with membrane filtration processes like reverse osmosis (RO) and nanofiltration (NF). Because the global demand for fresh clean water is increasing, these membrane technologies will increase in importance in the

  19. Space charge effect in the spiral inflector

    International Nuclear Information System (INIS)

    Toprek, Dragan

    2000-01-01

    This paper presents the analytical and numerical theory of the space charge effects in the beam in the spiral inflector. It considers a simplified model of a 'straight' cylindrical beam by using a uniform particle distribution. Numerical results represented in this paper are obtained by using a modified version of the program CASINO

  20. Some optical properties of the spiral inflector

    International Nuclear Information System (INIS)

    Toprek, Dragan; Subotic, Krunoslav

    1999-01-01

    This paper compares some optical properties of different spiral inflectors using the program CASINO. The electric field distribution in the inflectors has been numerically calculated from an electric potential map produced by the program RELAX3D. The magnetic field is assumed to be constant. We have also made an effort to minimize the inflector fringe field using the RELAX3D program. (author)

  1. A nutrient’s downstream spiral

    Science.gov (United States)

    Indicators of a stream’s ability to remove nutrients provide insights on watershed integrity and stream habitat characteristics that are needed to help managers to restore stream ecosystem services. We used the Tracer Additon Spiraling Characterization Curve (TASCC) to mea...

  2. Spiral groove seal. [for hydraulic rotating shaft

    Science.gov (United States)

    Ludwig, L. P. (Inventor)

    1973-01-01

    Mating flat surfaces inhibit leakage of a fluid around a stationary shaft. A spiral groove pattern produces a pumping action toward the fluid when the shaft rotates which prevents leakage while a generated hydraulic lifting force separates the mating surfaces to minimize wear.

  3. Logarithmic spiral trajectories generated by Solar sails

    Science.gov (United States)

    Bassetto, Marco; Niccolai, Lorenzo; Quarta, Alessandro A.; Mengali, Giovanni

    2018-02-01

    Analytic solutions to continuous thrust-propelled trajectories are available in a few cases only. An interesting case is offered by the logarithmic spiral, that is, a trajectory characterized by a constant flight path angle and a fixed thrust vector direction in an orbital reference frame. The logarithmic spiral is important from a practical point of view, because it may be passively maintained by a Solar sail-based spacecraft. The aim of this paper is to provide a systematic study concerning the possibility of inserting a Solar sail-based spacecraft into a heliocentric logarithmic spiral trajectory without using any impulsive maneuver. The required conditions to be met by the sail in terms of attitude angle, propulsive performance, parking orbit characteristics, and initial position are thoroughly investigated. The closed-form variations of the osculating orbital parameters are analyzed, and the obtained analytical results are used for investigating the phasing maneuver of a Solar sail along an elliptic heliocentric orbit. In this mission scenario, the phasing orbit is composed of two symmetric logarithmic spiral trajectories connected with a coasting arc.

  4. The Spiral Curriculum. Research into Practice

    Science.gov (United States)

    Johnston, Howard

    2012-01-01

    The Spiral Curriculum is predicated on cognitive theory advanced by Jerome Bruner (1960), who wrote, "We begin with the hypothesis that any subject can be taught in some intellectually honest form to any child at any stage of development." In other words, even the most complex material, if properly structured and presented, can be understood by…

  5. Spiral Growth in Plants: Models and Simulations

    Science.gov (United States)

    Allen, Bradford D.

    2004-01-01

    The analysis and simulation of spiral growth in plants integrates algebra and trigonometry in a botanical setting. When the ideas presented here are used in a mathematics classroom/computer lab, students can better understand how basic assumptions about plant growth lead to the golden ratio and how the use of circular functions leads to accurate…

  6. The Spiral-Interactive Program Evaluation Model.

    Science.gov (United States)

    Khaleel, Ibrahim Adamu

    1988-01-01

    Describes the spiral interactive program evaluation model, which is designed to evaluate vocational-technical education programs in secondary schools in Nigeria. Program evaluation is defined; utility oriented and process oriented models for evaluation are described; and internal and external evaluative factors and variables that define each…

  7. The handedness of historiated spiral columns.

    Science.gov (United States)

    Couzin, Robert

    2017-09-01

    Trajan's Column in Rome (AD 113) was the model for a modest number of other spiral columns decorated with figural, narrative imagery from antiquity to the present day. Most of these wind upwards to the right, often with a congruent spiral staircase within. A brief introductory consideration of antique screw direction in mechanical devices and fluted columns suggests that the former may have been affected by the handedness of designers and the latter by a preference for symmetry. However, for the historiated columns that are the main focus of this article, the determining factor was likely script direction. The manner in which this operated is considered, as well as competing mechanisms that might explain exceptions. A related phenomenon is the reversal of the spiral in a non-trivial number of reproductions of the antique columns, from Roman coinage to Renaissance and baroque drawings and engravings. Finally, the consistent inattention in academic literature to the spiral direction of historiated columns and the repeated publication of erroneous earlier reproductions warrants further consideration.

  8. Nobeyama CO Atlas of Nearby Spiral Galaxies

    Science.gov (United States)

    Kuno, N.; Nakai, N.; Sorai, K.; Sato, N..; Yamauchi, A.; Tosaki, T.; Shioya, Y.; Vila-Vilaró, B.; Nishiyama, K.; Ishihara, Y.; Cepa, J.

    BEARS is a 25-beam focal plane array receiver mounted on the Nobeyama 45-m telescope. The combination of the large dish size of the telescope with the excellent performance of this receiver makes it an ideal tool for mapping observations of extended regions of the sky. We present here one of its current applications in a CO mapping survey of nearby spiral galaxies.

  9. Predicting Vulnerability of the Integrity and Connectivity Associated with Culverts in Low Order Streams of Northern Michigan

    Science.gov (United States)

    King, C. H.; Wagenbrenner, J.; Fedora, M.; Watkins, D.; Watkins, M. K.; Huckins, C.

    2017-12-01

    The Great Lakes Region of North America has experienced more frequent extreme precipitation events in recent decades, resulting in a large number of stream crossing failures. While there are accepted methods for designing stream crossings to accommodate peak storm discharges, less attention has been paid to assessing the risk of failure. To evaluate failure risk and potential impacts, coarse-resolution stream crossing surveys were completed on 51 stream crossings and dams in the North Branch Paint River watershed in Michigan's Upper Peninsula. These inventories determined stream crossing dimensions along with stream and watershed characteristics. Eleven culverts were selected from the coarse surveys for high resolution hydraulic analysis to estimate discharge conditions expected at crossing failure. Watershed attributes upstream of the crossing, including area, slope, and storage, were acquired. Sediment discharge and the economic impact associated with a failure event were also estimated for each stream crossing. Impacts to stream connectivity and fish passability were assessed from the coarse-level surveys. Using information from both the coarse and high-resolution surveys, we also developed indicators to predict failure risk without the need for complex hydraulic modeling. These passability scores and failure risk indicators will help to prioritize infrastructure replacement and improve the overall connectivity of river systems throughout the upper Great Lakes Region.

  10. Spiral CT for evaluation of chest trauma; Spiral-CT beim Thoraxtrauma

    Energy Technology Data Exchange (ETDEWEB)

    Roehnert, W. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik; Weise, R. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik

    1997-07-01

    After implementation of spiral CT in our department, we carried out an analysis for determining anew the value of CT as a modality of chest trauma diagnosis in the emergency department. The retrospective study covers a period of 10 months and all emergency patients with chest trauma exmined by spiral CT. The major lesions of varying seriousness covered by this study are: pneumothorax, hematothorax, pulmonary contusion or laceration, mediastinal hematoma, rupture of a vessel, injury of the heart and pericardium. The various fractures are not included in this study. In many cases, spiral CT within relatively short time yields significant diagnostic findings, frequently saving additional angiography. A rigid diagnostic procedure cannot be formulated. Plain-film chest radiography still remains a diagnostic modality of high value. (Orig.) [Deutsch] Nach Einfuehrung der Spiral-CT in unserer Einrichtung versuchten wir, den Stellenwert der Computertomographie in der Notfalldiagnostik des Thoraxtraumas neu zu bestimmen. Dazu wurden retrospektiv ueber einen Zeitraum von 10 Monaten alle mittels Spiral-CT untersuchten Notfallpatienten mit Thoraxverletzungen ausgewertet. Im Vordergrund standen folgende Befunde unterschiedlichen Schweregrades: Pneumothorax, Haematothorax, Lungenkontusion/-lazeration, Mediastinalhaematom, Gefaessruptur, Herz- und Herzbeutelverletzung. Auf die unterschiedlichen Frakturen wird bewusst nicht naeher eingegangen. In vielen Faellen liefert die Spiral-CT mit relativ geringem Zeitaufwand wesentliche diagnostische Aussagen. Haeufig kann auf eine Angiographie verzichtet werden. Ein starres diagnostisches Stufenschema laesst sich nicht definieren. Die Thoraxuebersichtsaufnahme besitzt einen unveraendert hohen Stellenwert. (orig.)

  11. Nutrient spiraling in streams and river networks

    Science.gov (United States)

    Ensign, Scott H.; Doyle, Martin W.

    2006-12-01

    Over the past 3 decades, nutrient spiraling has become a unifying paradigm for stream biogeochemical research. This paper presents (1) a quantitative synthesis of the nutrient spiraling literature and (2) application of these data to elucidate trends in nutrient spiraling within stream networks. Results are based on 404 individual experiments on ammonium (NH4), nitrate (NO3), and phosphate (PO4) from 52 published studies. Sixty-nine percent of the experiments were performed in first- and second-order streams, and 31% were performed in third- to fifth-order streams. Uptake lengths, Sw, of NH4 (median = 86 m) and PO4 (median = 96 m) were significantly different (α = 0.05) than NO3 (median = 236 m). Areal uptake rates of NH4 (median = 28 μg m-2 min-1) were significantly different than NO3 and PO4 (median = 15 and 14 μg m-2 min-1, respectively). There were significant differences among NH4, NO3, and PO4 uptake velocity (median = 5, 1, and 2 mm min-1, respectively). Correlation analysis results were equivocal on the effect of transient storage on nutrient spiraling. Application of these data to a stream network model showed that recycling (defined here as stream length ÷ Sw) of NH4 and NO3 generally increased with stream order, while PO4 recycling remained constant along a first- to fifth-order stream gradient. Within this hypothetical stream network, cumulative NH4 uptake decreased slightly with stream order, while cumulative NO3 and PO4 uptake increased with stream order. These data suggest the importance of larger rivers to nutrient spiraling and the need to consider how stream networks affect nutrient flux between terrestrial and marine ecosystems.

  12. Utilization of the ion traps by SPIRAL

    International Nuclear Information System (INIS)

    Le Brun, C.; Lienard, E.; Mauger, F.; Tamain, B.

    1997-01-01

    An ion trap is a device capable of confine particles, ions or atoms in a well-controlled environment isolated from any exterior perturbations. There are different traps. They are utilized to collect or stock ions, to cool them after in order to subject them to high precision measurement of masses, magnetic moments, hyperfine properties, beta decay properties, etc. Some dozen of traps are currently used all over the world to study stable or radioactive ions.. SPIRAL has been designed and built to produce radioactive ions starting from various heavy ion beams. SPIRAL has the advantage that the projectile parameters, the target and the energy can be chosen to optimize the production in various regions of the nuclear chart. Also, in SPIRAL it is possible to extract more rapidly the radioactive ions formed in the targets. In addition, in SPIRAL the multicharged ion production in a ECR source is possible. The utilization of multicharged ions is indeed very useful for fast mass measurements or for the study of the interaction between the nucleus and the electronic cloud. Finally, utilization of a ion trap on SPIRAL can be designed first at the level of production target by installing a low energy output line. Than, the trap system could be up-graded and brought to its full utilization behind of the recoil spectrometer. It must be capable of selecting and slowing down the ions produced in the reactions (fusion transfer, very inelastic collisions, etc.) induced by the radioactive ions accelerated in CIME. At present, the collaboration is debating on the most favored subject to study and the most suited experimental setups. The following subjects were selected: ion capture, purification and manipulation; isomers (separation and utilization); mass measurements; hyperfine interactions; lifetimes, nuclear electric cloud; β decays; study of the N = Z nuclei close to the proton drip line; physical and chemical properties of transuranium systems

  13. Molecular clouds and galactic spiral structure

    International Nuclear Information System (INIS)

    Dame, T.M.

    1983-01-01

    Galactic CO line emission at 115 GHz has been surveyed in the region 12 0 less than or equal to l less than or equal to 60 0 and -1 0 less than or equal to b less than or equal to 1 0 in order to study the distribution of molecular clouds in the inner galaxy; an inner strip 0 0 .5 wide has been sampled every beamwidth (0 0 .125), the rest every two beamwidths. Comparison of the survey with similar HI data reveals a detailed correlation with the most intense 21-cm features, implying that the CO and HI trace the same galactic features and have the same large-scale kinematics. To each of the classical 21-cm (HI) spiral arms of the inner galaxy there corresponds a CO molecular arm which is generally more clearly defined and of higher contrast. A simple model is developed in which all of the CO emission from the inner galaxy arises from spiral arms. The modeling results suggest that molecular clouds are essentially transient objects, existing for 15 to 40 million years after their formation in a spiral arm, and are largely confined to spiral features about 300 pc wide. A variety of methods are employed to estimate distances and masses for the largest clouds detected by the inner-galaxy survey and a catalogue is compiled. The catalogued clouds, the largest of which have masses of several 10 6 M/sub sunmass/ and linear dimensions in excess of 100 pc, are found to be excellent spiral-arm tracers. One of the nearest of the clouds, that associated with the supernova remnant W44, is fully mapped in both CO and 13 CO and is discussed in detail

  14. Safe Control for Spiral Recovery of Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Chang-Jian Ru

    2014-01-01

    Full Text Available With unmanned aerial vehicles (UAVs widely used in both military and civilian fields, many events affecting their safe flying have emerged. That UAV’s entering into the spiral is such a typical safety issue. To solve this safety problem, a novel recovery control approach is proposed. First, the factors of spiral are analyzed. Then, based on control scheduling of state variables and nonlinear dynamic inversion control laws, the spiral recovery controller is designed to accomplish guidance and control of spiral recovery. Finally, the simulation results have illustrated that the proposed control method can ensure the UAV autonomous recovery from spiral effectively.

  15. U-rans model for the prediction of the acoustic sound power generated in a whistling corrugated pipe

    NARCIS (Netherlands)

    Golliard, J.; González Díez, N.; Belfroid, S.P.C.; Nakiboǧlu, G.; Hirschberg, A.

    2013-01-01

    Corrugated pipes, as used in flexible risers for gas production or in domestic appliances, can whistle when a flow is imposed through the pipe. Nakiboglu et al [1, 2] have developed a method to compute the acoustic source term for axi-symmetric cavities. The method is based on the resolution of

  16. Impact of interfacial imperfection on transverse wave in a functionally graded piezoelectric material structure with corrugated boundaries

    Science.gov (United States)

    Kumar Singh, Abhishek; Kumar, Santan; Kumari, Richa

    2018-03-01

    The propagation behavior of Love-type wave in a corrugated functionally graded piezoelectric material layered structure has been taken into account. Concretely, the layered structure incorporates a corrugated functionally graded piezoelectric material layer imperfectly bonded to a functionally graded piezoelectric material half-space. An analytical treatment has been employed to determine the dispersion relation for both cases of electrically open condition and electrically short condition. The phase velocity of the Love-type wave has been computed numerically and its dependence on the wave number has been depicted graphically for a specific type of corrugated boundary surfaces for both said conditions. The crux of the study lies in the fact that the imperfect bonding of the interface, the corrugated boundaries present in the layer, and the material properties of the layer and the half-space strongly influence the phase velocity of the Love-type wave. It can be remarkably noted that the imperfect bonding of the interface reduces the phase velocity of the Love-type wave significantly. As a special case of the problem, it is noticed that the procured dispersion relation for both cases of electrically open and electrically short conditions is in accordance with the classical Love wave equation.

  17. How does a planet excite multiple spiral arms?

    Science.gov (United States)

    Bae, Jaehan; Zhu, Zhaohuan

    2018-01-01

    Protoplanetary disk simulations show that a single planet excites multiple spiral arms in the background disk, potentially supported by the multi-armed spirals revealed with recent high-resolution observations in some disks. The existence of multiple spiral arms is of importance in many aspects. It is empirically found that the arm-to-arm separation increases as a function of the planetary mass, so one can use the morphology of observed spiral arms to infer the mass of unseen planets. In addition, a spiral arm opens a radial gap as it steepens into a shock, so when a planet excites multiple spiral arms it can open multiple gaps in the disk. Despite the important implications, however, the formation mechanism of multiple spiral arms has not been fully understood by far.In this talk, we explain how a planet excites multiple spiral arms. The gravitational potential of a planet can be decomposed into a Fourier series, a sum of individual azimuthal modes having different azimuthal wavenumbers. Using a linear wave theory, we first demonstrate that appropriate sets of Fourier decomposed waves can be in phase, raising a possibility that constructive interference among the waves can produce coherent structures - spiral arms. More than one spiral arm can form since such constructive interference can occur at different positions in the disk for different sets of waves. We then verify this hypothesis using a suite of two-dimensional hydrodynamic simulations. Finally, we present non-linear behavior in the formation of multiple spiral arms.

  18. Model for the local spiral structure of the galaxy

    International Nuclear Information System (INIS)

    Humphreys, R.M.

    1976-01-01

    The spatial distribution of the most luminous stars, associations, clusters, and H II regions in the region l = 270 0 to 30 0 reveal a major spiral arm, Sagittarius-Carina, which can be observed to 9 or 10 kpc from the sun in the direction l = 290 0 to 305 0 . Evidence is also presented for a spur at l = 305 0 to 310 0 on the inner side of the Saggitarius-Carina arm. The noncircular motions observed in the Carina and Sagittarius spiral features agree in both magnitude and direction and support the suggestion that Sagittarius-Carina is a major spiral arm. A model is presented for the local spiral structure with wide, massive, spiral arms which show fragmentation in our region of the Galaxy. On the basis of the optical spiral structure, the Milky Way is an Sc type spiral galaxy, perhaps of the M 101 type

  19. Mechanism of spiral formation in heterogeneous discretized excitable media.

    Science.gov (United States)

    Kinoshita, Shu-ichi; Iwamoto, Mayuko; Tateishi, Keita; Suematsu, Nobuhiko J; Ueyama, Daishin

    2013-06-01

    Spiral waves on excitable media strongly influence the functions of living systems in both a positive and negative way. The spiral formation mechanism has thus been one of the major themes in the field of reaction-diffusion systems. Although the widely believed origin of spiral waves is the interaction of traveling waves, the heterogeneity of an excitable medium has recently been suggested as a probable cause. We suggest one possible origin of spiral waves using a Belousov-Zhabotinsky reaction and a discretized FitzHugh-Nagumo model. The heterogeneity of the reaction field is shown to stochastically generate unidirectional sites, which can induce spiral waves. Furthermore, we found that the spiral wave vanished with only a small reduction in the excitability of the reaction field. These results reveal a gentle approach for controlling the appearance of a spiral wave on an excitable medium.

  20. Growth of InP directly on Si by corrugated epitaxial lateral overgrowth

    International Nuclear Information System (INIS)

    Metaferia, Wondwosen; Kataria, Himanshu; Sun, Yan-Ting; Lourdudoss, Sebastian

    2015-01-01

    In an attempt to achieve an InP–Si heterointerface, a new and generic method, the corrugated epitaxial lateral overgrowth (CELOG) technique in a hydride vapor phase epitaxy reactor, was studied. An InP seed layer on Si (0 0 1) was patterned into closely spaced etched mesa stripes, revealing the Si surface in between them. The surface with the mesa stripes resembles a corrugated surface. The top and sidewalls of the mesa stripes were then covered by a SiO 2 mask after which the line openings on top of the mesa stripes were patterned. Growth of InP was performed on this corrugated surface. It is shown that growth of InP emerges selectively from the openings and not on the exposed silicon surface, but gradually spreads laterally to create a direct interface with the silicon, hence the name CELOG. We study the growth behavior using growth parameters. The lateral growth is bounded by high index boundary planes of {3 3 1} and {2 1 1}. The atomic arrangement of these planes, crystallographic orientation dependent dopant incorporation and gas phase supersaturation are shown to affect the extent of lateral growth. A lateral to vertical growth rate ratio as large as 3.6 is achieved. X-ray diffraction studies confirm substantial crystalline quality improvement of the CELOG InP compared to the InP seed layer. Transmission electron microscopy studies reveal the formation of a direct InP–Si heterointerface by CELOG without threading dislocations. While CELOG is shown to avoid dislocations that could arise due to the large lattice mismatch (8%) between InP and Si, staking faults could be seen in the layer. These are probably created by the surface roughness of the Si surface or SiO 2 mask which in turn would have been a consequence of the initial process treatments. The direct InP–Si heterointerface can find applications in high efficiency and cost-effective Si based III–V semiconductor multijunction solar cells and optoelectronics integration. (paper)

  1. Effects of carbon coating and pore corrugation on capillary condensation of nitrogen in SBA-15 mesoporous silica.

    Science.gov (United States)

    Morishige, Kunimitsu

    2013-09-24

    To examine the origin of an ink-bottle-like structure in SBA-15 formed by carbon coating and the effects of pore corrugation on capillary condensation and evaporation of a vapor in the cylindrical pores, we measured the adsorption isotherms of nitrogen at 77 K on 10 kinds of SBA-15 samples before and after a carbon coating process by the exposure to acetylene at 1073 K, as well as desorption scanning curves and subloops on the untreated samples. These SBA-15 samples were synthesized under the different conditions of initial SiO2/P123 ratio and hydrothermal treatment. SBA-15 with relatively large microporosity tends to form easily constrictions inside the main channels by the carbon coating. This strongly suggests that the rough pore walls of SBA-15 may induce the incomplete wetting of carbon layers on the pore walls to form the constrictions inside the cylindrical pores. A comparison of two subloops implies that the pores of SBA-15 synthesized with a SiO2/P123 ratio of 75 consist of an assembly of connecting domains of different diameters; that is, the pores are highly corrugated. For SBA-15 synthesized with a SiO2/P123 ratio of 60, the amplitude of the pore corrugation is significantly decreased by the prolonged hydrothermal treatment at 373 K. On the other hand, for SBA-15 synthesized with a SiO2/P123 ratio of 45, the amplitude of the corrugation is negligibly small, although the cylindrical pores are interconnected through narrow necks with each other. It is found that the smaller the amplitude of the pore corrugation, the smaller the width of the hysteresis loop.

  2. Fabrication of 20 nm half-pitch gratings by corrugation-directed self-assembly

    International Nuclear Information System (INIS)

    Kim, Ho-Cheol; Rettner, Charles T; Sundstroem, Linnea

    2008-01-01

    The evolution of the scaling of modern semiconductor devices is governed by the ability to create scalable high-resolution patterns on substrates. Since it is becoming increasingly difficult and expensive to extend to smaller dimensions using optical lithography, there is a great deal of interest in alternative patterning methods. The self-assembly of block copolymers in thin films, which provides periodic patterns of 10-50 nm length scales, has been recognized as a promising candidate for such patterning. To be practical, however, this approach must provide control over the orientation and lateral placement of the microdomains. We report here our discovery of the controlled alignment of the lamellar microdomains of a block copolymer containing hybrid material using topographic pre-patterns on substrates. We find that this hybrid material forms lamellae with a half-pitch of approximately 20 nm perpendicular to the lines of a surface corrugation

  3. Particular treatments in Eddy current technique. Application to the control of corrugated tubes

    International Nuclear Information System (INIS)

    1982-11-01

    When the testing of a given product shows that, owing to a particular shape of this product or to its environment, disturbing effects can hide the presence of harmful defects, use must be made of testing artifices or particular treatments enabling an efficient examination to be made. On this score, many eddy current problems are solved by means of the following processes: - use of specific sensors adapted to the geometry of the product, - spectral analysis of the analog results of analyses, - combination of the results of analyses obtained simultaneously at different frequencies (multifrequency techniques). An example of an application is given for corrugated tubes achieved by hollow and helical milling of smooth tubes [fr

  4. Dynamical back-action at 5.5 GHz in a corrugated optomechanical beam

    Energy Technology Data Exchange (ETDEWEB)

    Navarro-Urrios, D., E-mail: daniel.navarrourrios@nano.cnr.it [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); NEST, Istituto Nanoscienze – CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, I-56127 (Italy); Gomis-Bresco, J.; Alzina, F. [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); El-Jallal, S. [IEMN, Universite de Lille 1, Villeneuve d’Ascq (France); PRILM, Université Moulay Ismail, Faculté des sciences, Meknès (Morocco); Oudich, M.; Pennec, Y.; Djafari-Rouhani, B. [IEMN, Universite de Lille 1, Villeneuve d’Ascq (France); Pitanti, A. [NEST, Istituto Nanoscienze – CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, I-56127 (Italy); Capuj, N. [Depto. Física, Universidad de la Laguna, 38206 (Spain); Tredicucci, A. [NEST, Istituto Nanoscienze – CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, I-56127 (Italy); Dipartimento di Fisica, Universita di Pisa, Largo Pontecorvo 3, I-56127 Pisa (Italy); Griol, A.; Martínez, A. [Nanophotonics Technology Center, Universitat Politècnica de València, Valencia (Spain); Sotomayor Torres, C. M. [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); Catalan Institution for Research and Advanced Studies (ICREA), 08010 Barcelona (Spain)

    2014-12-15

    We report on the optomechanical properties of a breathing mechanical mode oscillating at 5.5 GHz in a 1D corrugated Si nanobeam. This mode has an experimental single-particle optomechanical coupling rate of |g{sub o,OM}| = 1.8 MHz (|g{sub o,OM}|/2π = 0.3 MHz) and shows strong dynamical back-action effects at room temperature. The geometrical flexibility of the unit-cell would lend itself to further engineering of the cavity region to localize the mode within the full phononic band-gap present at 4 GHz while keeping high g{sub o,OM} values. This would lead to longer lifetimes at cryogenic temperatures, due to the suppression of acoustic leakage.

  5. SPREADING OF A FLUID JET ON THE CORRUGATED SURFACE OF THE STRUCTURED PACKING OF WET SCRUBBERS

    Directory of Open Access Journals (Sweden)

    Gorodilov A.A.

    2014-08-01

    Full Text Available The new packing for wet scrubbers for cooling exhaust gases of furnaces is presented. Spreading features of the fluid jet on the corrugated surface of the proposed packing have been studied. Flow rate of the liquid flowing through slits to the opposite side of the packing element was determined. Several regimes of a fluid flow on the surface of the proposed structured packing were determined. An optimal range of rational flow rates for more intense cooling of exhaust gases is proposed. It was discovered that the range of optimum flow rates may be extended if the surface of the packing element is pre-wetted. The way of increasing the rate of effective interfacial surface area for gas-liquid contact per unit volume of the packing of the scrubber is presented.

  6. Flows of Newtonian and Power-Law Fluids in Symmetrically Corrugated Cappilary Fissures and Tubes

    Science.gov (United States)

    Walicka, A.

    2018-02-01

    In this paper, an analytical method for deriving the relationships between the pressure drop and the volumetric flow rate in laminar flow regimes of Newtonian and power-law fluids through symmetrically corrugated capillary fissures and tubes is presented. This method, which is general with regard to fluid and capillary shape, can also be used as a foundation for different fluids, fissures and tubes. It can also be a good base for numerical integration when analytical expressions are hard to obtain due to mathematical complexities. Five converging-diverging or diverging-converging geometrics, viz. wedge and cone, parabolic, hyperbolic, hyperbolic cosine and cosine curve, are used as examples to illustrate the application of this method. For the wedge and cone geometry the present results for the power-law fluid were compared with the results obtained by another method; this comparison indicates a good compatibility between both the results.

  7. Distributed feedback interband cascade lasers with top grating and corrugated sidewalls

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Feng [Thorlabs Quantum Electronics, 10335 Guilford Rd, Jessup, Maryland 20794, USA; Stocker, Michael [Thorlabs Quantum Electronics, 10335 Guilford Rd, Jessup, Maryland 20794, USA; Pham, John [Thorlabs Quantum Electronics, 10335 Guilford Rd, Jessup, Maryland 20794, USA; Towner, Frederick [Thorlabs Quantum Electronics, 10335 Guilford Rd, Jessup, Maryland 20794, USA; Shen, Kun [Thorlabs Quantum Electronics, 10335 Guilford Rd, Jessup, Maryland 20794, USA; Wang, Jie [Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, USA; Lascola, Kevin [Thorlabs Quantum Electronics, 10335 Guilford Rd, Jessup, Maryland 20794, USA

    2018-03-26

    Distributed feedback (DFB) interband cascade lasers (ICLs) with a 1st order top surface grating were designed and fabricated. Partially corrugated sidewalls were implemented to suppress high order lateral modes. The DFB ICLs have 4 mm long and 4.5 mu m wide ridge waveguides and are mounted epi-up on AlN submounts. We demonstrated a continuous-wave (CW) DFB ICL, from a first wafer which has a large detuning of the gain peak from the DFB wavelength, with a side mode suppression ratio of 30 dB. With proper matching of grating feedback and the gain peak wavelength for the second wafer, a DFB ICL was demonstrated with a maximum CW output power and a maximum wall plug efficiency reaching 42 mW and 2%, respectively, at 25 degrees C. The lasing wavelengths of both lasers are around 3.3 mu m at 25 degrees C. Published by AIP Publishing.

  8. Asymptotic freeze-out of the perturbations generated inside a corrugated rarefaction wave

    International Nuclear Information System (INIS)

    Wouchuk, J.G.; Serrano Rodrigo, A.D.

    2004-01-01

    Based on previous work [J. G. Wouchuk and R. Carretero, Phys. Plasmas 10, 4237 (2003)], the conditions of asymptotic freeze-out of the ripples at the tail of a corrugated rarefaction wave are analyzed. The precise location of the freezing-out regions in the space of preshock parameters is tried, and an efficient algorithm for their determination is given. It is seen that asymptotic freeze-out can only happen for gases that have an isentropic exponent γ cr ≅2.2913hellip. It is shown that the late time freeze-out of the ripple perturbations is correlated to the initial tangential velocity profile (at t=0+) inside the expansion fan

  9. Optimization of a Conical Corrugated Antenna Using Multiobjective Heuristics for Radio-Astronomy Applications

    Directory of Open Access Journals (Sweden)

    S. López-Ruiz

    2016-01-01

    Full Text Available This paper presents the design of a tree sections corrugated horn antenna with a modified linear profile, using NURBS, suitable for radio-astronomy applications. The operating band ranges from 4.5 to 8.8 GHz. The aperture efficiency is higher than 84% and the return losses are greater than 20 dB in the whole bandwidth. The antenna optimization has been carried out with multiobjective versions of an evolutionary algorithm (EA and a particle swarm optimization (PSO algorithm. We show that both techniques provide good antenna design, but the experience carried out shows that the results of the evolutionary algorithm outperform the particle swarm results.

  10. ANALYSIS OF LOGISTICS AND SUPPLY CHAIN MANAGEMENT AGILITY IN CORRUGATED BOX INDUSTRY

    Directory of Open Access Journals (Sweden)

    Yosef Daryanto

    2016-04-01

    Full Text Available Several analyses were performed in this case study including the analysis of the business environments and the current supply chain system, which than followed by measurement and comparison of supply chain agility performance indicator. As corrugated box industry work in make/engineer to order system and by considering their competitive situation and uncertain business environment it was concluded that they need agility in their supply chain. The main problem was the unbalance power position with paper supplier that resulting low inbound inventory turns. Focusing on this weakness, two solutions were proposed; those are building higher collaboration with paper suppliers and performing better inventory management by set different inventory control and policy for each inventory class

  11. Flows of Newtonian and Power-Law Fluids in Symmetrically Corrugated Cappilary Fissures and Tubes

    Directory of Open Access Journals (Sweden)

    Walicka A.

    2018-02-01

    Full Text Available In this paper, an analytical method for deriving the relationships between the pressure drop and the volumetric flow rate in laminar flow regimes of Newtonian and power-law fluids through symmetrically corrugated capillary fissures and tubes is presented. This method, which is general with regard to fluid and capillary shape, can also be used as a foundation for different fluids, fissures and tubes. It can also be a good base for numerical integration when analytical expressions are hard to obtain due to mathematical complexities. Five converging-diverging or diverging-converging geometrics, viz. wedge and cone, parabolic, hyperbolic, hyperbolic cosine and cosine curve, are used as examples to illustrate the application of this method. For the wedge and cone geometry the present results for the power-law fluid were compared with the results obtained by another method; this comparison indicates a good compatibility between both the results.

  12. Using pipe with corrugated walls for a subterahertz free electron laser

    Directory of Open Access Journals (Sweden)

    Gennady Stupakov

    2015-03-01

    Full Text Available A metallic pipe with corrugated walls supports propagation of a high-frequency mode that is in resonance with a relativistic beam propagating along the axis of the pipe. This mode can be excited by a beam whose length is a fraction of the wavelength. In this paper, we study another option of excitation of the resonant mode—via the mechanism of the free electron laser instability. This mechanism works if the bunch length is much longer than the wavelength of the radiation and, hence, does not require bunch compression. It provides an alternative to excitation by short bunches that can be realized with relatively low energy and low peak-current electron beams.

  13. Theory of the corrugation instability of a piston-driven shock wave.

    Science.gov (United States)

    Bates, J W

    2015-01-01

    We analyze the two-dimensional stability of a shock wave driven by a steadily moving corrugated piston in an inviscid fluid with an arbitrary equation of state. For h≤-1 or h>h(c), where h is the D'yakov parameter and h(c) is the Kontorovich limit, we find that small perturbations on the shock front are unstable and grow--at first quadratically and later linearly--with time. Such instabilities are associated with nonequilibrium fluid states and imply a nonunique solution to the hydrodynamic equations. The above criteria are consistent with instability limits observed in shock-tube experiments involving ionizing and dissociating gases and may have important implications for driven shocks in laser-fusion, astrophysical, and/or detonation studies.

  14. The peeling behaviour of a graphene sheet on a nano-scale corrugated surface

    International Nuclear Information System (INIS)

    Chen, Hao; Chen, Shaohua

    2013-01-01

    The peeling process and average peeling force of a graphene (GE) sheet on a corrugated surface are investigated using molecular dynamics simulation. It is found that the peeling behaviour varies with the substrate surface roughness and the peeling angle. Three kinds of typically peeling behaviours include (a) GE sheet directly passing the valley of the substrate roughness; (b) bouncing off from the substrate; and (c) continuously peeling off similarly to that on a flat substrate. As a result, the average peeling force is strongly dependent of the peeling behaviours. Furthermore, some interesting phenomena are caught, such as partial detaching and partial sliding of GE sheet in the valley of the substrate roughness, which are mainly due to the effects of pre-tension in GE sheet and the reduction of friction resistance. The results in this paper should be useful for the design of nano-film/substrate systems. (paper)

  15. Thermo-hydraulic characterization of a self-pumping corrugated wall heat exchanger

    International Nuclear Information System (INIS)

    Schmidmayer, Kevin; Kumar, Prashant; Lavieille, Pascal; Miscevic, Marc; Topin, Frédéric

    2017-01-01

    Compactness, efficiency and thermal control of the heat exchanger are of critical significance for many electronic industry applications. In this view, a new concept of heat exchanger at millimeter scale is proposed and numerically studied. It consists in dynamically deforming at least one of its walls by a progressive wave in order to create an active corrugated channel. Systematic studies were performed in single-phase flow on the different deformation parameters that allow obtaining the thermo-hydraulic characteristics of the system. It has been observed the dynamic wall deformation induces a significant pumping effect. Intensification of heat transfer remains very important even for highly degraded waveforms although the pumping efficiency is reduced in this case. The mechanical power applied on the upper wall to deform it dynamically is linked to the wave shape, amplitude, frequency and outlet-inlet pressure difference. The overall performance of the proposed system has been evaluated and compared to existing static channels. The performance of the proposed heat exchanger evolved in two steps for a given wall deformation. It declines slightly up to a critical value of mechanical power applied on the wall. When this critical value is exceeded, it deteriorates significantly, reaching the performance of existing conventional systems. - Highlights: • A new concept of heat exchanger within channel at millimeter scale is proposed. • Upper wall is deformed dynamically by applying external mechanical power. • Pumping effect is observed and is linked to the wave shape, amplitude and frequency. • Efficient proposed system in low Reynolds number range. • Overall performance is significantly high compared to static corrugated and straight channels.

  16. Radial distributions of arm-gas offsets as an observational test of spiral theories

    OpenAIRE

    Baba, Junichi; Morokuma-Matsui, Kana; Egusa, Fumi

    2015-01-01

    Theories of stellar spiral arms in disk galaxies can be grouped into two classes based on the longevity of a spiral arm. Although the quasi-stationary density wave theory supposes that spirals are rigidly-rotating, long-lived patterns, the dynamic spiral theory predicts that spirals are differentially-rotating, transient, recurrent patterns. In order to distinguish between the two spiral models from observations, we performed hydrodynamic simulations with steady and dynamic spiral models. Hyd...

  17. Spiral optical designs for nonimaging applications

    Science.gov (United States)

    Zamora, Pablo; Benítez, Pablo; Miñano, Juan C.; Vilaplana, Juan; Buljan, Marina

    2011-10-01

    Manufacturing technologies as injection molding or embossing specify their production limits for minimum radii of the vertices or draft angle for demolding, for instance. In some demanding nonimaging applications, these restrictions may limit the system optical efficiency or affect the generation of undesired artifacts on the illumination pattern. A novel manufacturing concept is presented here, in which the optical surfaces are not obtained from the usual revolution symmetry with respect to a central axis (z axis), but they are calculated as free-form surfaces describing a spiral trajectory around z axis. The main advantage of this new concept lies in the manufacturing process: a molded piece can be easily separated from its mold just by applying a combination of rotational movement around axis z and linear movement along axis z, even for negative draft angles. Some of these spiral symmetry examples will be shown here, as well as their simulated results.

  18. Diagnosing extracranial atherosclerotic diseases with spiral CT

    International Nuclear Information System (INIS)

    Moran, C.J.; Vannier, M.W.; Erickson, K.K.; Broderick, D.F.; Kido, D.K.; Yoffie, R.L.

    1991-01-01

    This paper reports that this discovery study was performed to determine whether extracranial carotid artery plaques could be diagnosed with a new CT technique (spiral CT) that allows nondistorted three-dimensional (3D) reconstructions in the z axis. Twenty carotid arteries were examined with spiral CT in normal volunteers and in patients suspected of having atherosclerotic plaques in the extracranial carotid arteries. The Somatom Plus CT table was advanced at a constant rate, the x-ray tube was continuously rotated, and 3D data were continuously acquired. Sixty milliliters of nonionic contrast medium was injected intravenously previous to and during the acquisition of data. The carotid bifurcations were identified in all patients. Planar images, similar to conventional intraarterial angiograms, were routinely produced from the volumetric CT data

  19. Status of the SPIRAL2 injector commissioning

    Energy Technology Data Exchange (ETDEWEB)

    Thuillier, T., E-mail: thuillier@lpsc.in2p3.fr; Angot, J.; Jacob, J.; Lamy, T.; Sole, P. [LPSC, Université Grenoble Alpes, CNRS/IN2P3, 53 rue des Martyrs, 38026 Grenoble Cedex (France); Barué, C.; Bertrand, P.; Canet, C.; Ferdinand, R.; Flambard, J.-L.; Jardin, P.; Lemagnen, F.; Maunoury, L.; Osmond, B. [GANIL, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, 14076 Caen Cedex 5 (France); Biarrotte, J. L. [IPN Orsay, Université Paris Sud, CNRS/IN2P3, 15 rue Georges Clémenceau, 91406 Orsay Cedex (France); Denis, J.-F.; Roger, A.; Touzery, R.; Tuske, O.; Uriot, D. [Irfu, CEA Saclay, DSM/Irfu/SACM, 91191 Gif Sur Yvette (France); and others

    2016-02-15

    The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ∼50. A status of its assembly is proposed.

  20. Rolling motions in an inner spiral arm

    International Nuclear Information System (INIS)

    Strauss, F.M.; Poeppel, W.

    1976-01-01

    Hydrogen line observations made at low galactic latitudes for l=318degree, 326degree, 334degree, and 337degree show the presence of velocity gradients in latitude in the nearest inner spiral arm, similar to those found by other observations in different regions. Maximum velocity change is about 10 km s -1 for l=337degree. By generating synthetic line profiles constructed from a model spiral arm, several possible causes of these ''rolling motions'' were studied, such as a vertical displacement or a tilt of the arm (which failed to account for the observations) and rotation or shearing in the arm. It was futher shown that a typical arm can maintain such a motion (approx. =75 km s -1 kpc -1 ) with its own gravitational potential. The results are used to study the origin and tilt of Gould's Belt

  1. Stationary spiral flow in polytropic stellar models

    Science.gov (United States)

    Pekeris, C. L.

    1980-01-01

    It is shown that, in addition to the static Emden solution, a self-gravitating polytropic gas has a dynamic option in which there is stationary flow along spiral trajectories wound around the surfaces of concentric tori. The motion is obtained as a solution of a partial differential equation which is satisfied by the meridional stream function, coupled with Poisson's equation and a Bernoulli-type equation for the pressure (density). The pressure is affected by the whole of the Bernoulli term rather than by the centrifugal part only, which acts for a rotating model, and it may be reduced down to zero at the center. The spiral type of flow is illustrated for an incompressible fluid (n = 0), for which an exact solution is obtained. The features of the dynamic constant-density model are discussed as a basis for future comparison with the solution for compressible models. PMID:16592825

  2. Gastric spiral bacteria in small felids.

    Science.gov (United States)

    Kinsel, M J; Kovarik, P; Murnane, R D

    1998-06-01

    Nine small cats, including one bobcat (Felis rufus), one Pallas cat (F. manul), one Canada lynx (F. lynx canadensis), two fishing cats (F. viverrina), two margays (F. wiedii), and two sand cats (F. margarita), necropsied between June 1995 and March 1997 had large numbers of gastric spiral bacteria, whereas five large cats, including one African lion (Panthera leo), two snow leopards (P. uncia), one Siberian tiger (P. tigris altaica), and one jaguar (P. onca), necropsied during the same period had none. All of the spiral organisms from the nine small cats were histologically and ultrastructurally similar. Histologically, the spiral bacteria were 5-14 microm long with five to nine coils per organism and were located both extracellularly within gastric glands and surface mucus, and intracellularly in parietal cells. Spiral bacteria in gastric mucosal scrapings from the Canada lynx, one fishing cat, and the two sand cats were gram negative and had corkscrewlike to tumbling motility when viewed with phase contrast microscopy. The bacteria were 0.5-0.7 microm wide, with a periodicity of 0.65-1.1 microm in all cats. Bipolar sheathed flagella were occasionally observed, and no periplasmic fibrils were seen. The bacteria were extracellular in parietal cell canaliculi and intracellular within parietal cells. Culture of mucosal scrapings from the Canada lynx and sand cats was unsuccessful. Based on morphology, motility, and cellular tropism, the bacteria were probably Helicobacter-like organisms. Although the two margays had moderate lymphoplasmacytic gastritis, the other cats lacked or had only mild gastric lymphoid infiltrates, suggesting that these organisms are either commensals or opportunistic pathogens.

  3. Star distribution in the Orion spiral arm

    International Nuclear Information System (INIS)

    Basharina, T.S.; Pavlovskaya, E.D.; Filippova, A.A.

    1985-01-01

    The structure of the Orion spiral arm is studied by numerical experiments, assuming that in each direction considered the star distribution along the line of sight is a combination of two Gaussian laws. The corresponding parameters are evaluated for four Milky Way fields; the bimodal laws now fit the observations by the chi 2 criterion. In the Orion arm the line-of-sight star densities follow asymmetric curves, steeper at the outer edge of the arm

  4. The surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.

    1983-01-01

    It is proposed that Freeman's discovery that the extrapolated central surface brightness of spiral galaxies is approximately constant can be simply explained if the galaxies contain a spheroidal component which dominates the light in their outer isophotes. Calculations of an effective central surface brightness indicate a wide spread of values. This requires either a wide spread in disc properties or significant spheroidal components or, most probably, both. (author)

  5. A Fermat's spiral multifilament-core fiber

    Science.gov (United States)

    Tartara, L.; Codemard, C.

    2013-02-01

    A multifilament-core optical fiber where the microstructure is arranged in a Fermat's spiral is presented. The properties of such a fiber to be exploited for laser light amplification are numerically investigated by means of a full-vectorial finite-element method. Thanks to this peculiar microstructure, the fiber is shown to have an increased Brillouin threshold power and very low bending losses, while preserving a very good beam spatial quality.

  6. Spiral-arm instability: giant clump formation via fragmentation of a galactic spiral arm

    Science.gov (United States)

    Inoue, Shigeki; Yoshida, Naoki

    2018-03-01

    Fragmentation of a spiral arm is thought to drive the formation of giant clumps in galaxies. Using linear perturbation analysis for self-gravitating spiral arms, we derive an instability parameter and define the conditions for clump formation. We extend our analysis to multicomponent systems that consist of gas and stars in an external potential. We then perform numerical simulations of isolated disc galaxies with isothermal gas, and compare the results with the prediction of our analytic model. Our model describes accurately the evolution of the spiral arms in our simulations, even when spiral arms dynamically interact with one another. We show that most of the giant clumps formed in the simulated disc galaxies satisfy the instability condition. The clump masses predicted by our model are in agreement with the simulation results, but the growth time-scale of unstable perturbations is overestimated by a factor of a few. We also apply our instability analysis to derive scaling relations of clump properties. The expected scaling relation between the clump size, velocity dispersion, and circular velocity is slightly different from that given by the Toomre instability analyses, but neither is inconsistent with currently available observations. We argue that the spiral-arm instability is a viable formation mechanism of giant clumps in gas-rich disc galaxies.

  7. Incorporating hydrologic variability into nutrient spiraling

    Science.gov (United States)

    Doyle, Martin W.

    2005-09-01

    Nutrient spiraling describes the path of a nutrient molecule within a stream ecosystem, combining the biochemical cycling processes with the downstream driving force of stream discharge. To date, nutrient spiraling approaches have been hampered by their inability to deal with fluctuating flows, as most studies have characterized nutrient retention within only a small range of discharges near base flow. Here hydrologic variability is incorporated into nutrient spiraling theory by drawing on the fluvial geomorphic concept of effective discharge. The effective discharge for nutrient retention is proposed to be that discharge which, over long periods of time, is responsible for the greatest portion of nutrient retention. A developed analytical model predicts that the effective discharge for nutrient retention will equal the modal discharge for small streams or those with little discharge variability. As modal discharge increases or discharge variability increases, the effective discharge becomes increasingly less than the modal discharge. In addition to the effective discharge, a new metric is proposed, the functionally equivalent discharge, which is the single discharge that will reproduce the magnitude of nutrient retention generated by the full hydrologic frequency distribution when all discharge takes place at that rate. The functionally equivalent discharge was found to be the same as the modal discharge at low hydrologic variability, but increasingly different from the modal discharge at large hydrologic variability. The functionally equivalent discharge provides a simple quantitative means of incorporating hydrologic variability into long-term nutrient budgets.

  8. Rarefied, rotational gas flows in spiral galaxies

    International Nuclear Information System (INIS)

    Roberts, W.W. Jr.; Hausman, M.A.

    1983-01-01

    We develop a computational model of a rotating, rarefied gas in which the individual molecules collide inelastically and are subject to circularly asymmetric external forces and internal heating sources. This model is applied to the interstellar medium (ISM) of spiral galaxies, in which most of the matter is confined to discrete gas clouds separated by a tenuous intercloud medium. We identify inelastically-colliding gas molecules with interstellar clouds which orbit ballistically in the galactic gravitational field and are perturbed by expanding shells surrounding supernovae. When a small, spiral perturbation is added to the gravitational force to mimic a spiral galaxy, the cloud distribution responds with a strong, global shock. In the model, stars are formed from the gas when clouds collide or are perturbed by supernovae; these stars are the internal heating sources for the gas cloud system. We determine the morphologies (evolution, distribution) of the two components, gas and stars, in the model as functions of varying input physics. Variation of the cloud system's collisional mean free path (over physically-realistic ranges) has remarkably little influence on the computed shock structure

  9. The 1+/n+ solution for SPIRAL ?

    International Nuclear Information System (INIS)

    Villari, A.C.C.; Bruandet, J.S.; Chauvin, N.; Curdy, J.C.; Gaubert, G.; Lamy, T.; Maunoury, L.; Sole, J.P.; Sortais, P.; Vieux-Rochaz, J.L.

    1997-01-01

    The use of a primary ion source for the production of 1+ ions in the production cave of SPIRAL with subsequent injection in an ECRIS (Electron Cyclotron Resonance Ion Source) for charge multiplication is discussed. The first results obtained at ISN Grenoble for the production of Rb (9+) and Ar (8+) stable beams are presented. The overall efficiency of this system for the production of the Ar beams is compared with the present situation where the ECRIS is placed inside the cave of SPIRAL. An important gain in the reliability and reduction of functioning costs would be obtained in the case of the implementation of the 1+/n+ mode in the SPIRAL project at GANIL. A reduction of overall efficiency of a factor 1.5 to 3 with respect to the present NANOGAN-II ensemble is expected for light noble gas radioactive ion beams. This factor can be reduced depending on the choice of the ECRIS for a particular multicharged ion production. Finally, important R and D is needed for extending the range of elements to be produced in the 1+/n+ mode and to define 'good' ion sources with small energy dispersion for 1+ production. (authors)

  10. Transitions between Taylor vortices and spirals via wavy Taylor vortices and wavy spirals

    International Nuclear Information System (INIS)

    Hoffmann, Ch; Altmeyer, S; Pinter, A; Luecke, M

    2009-01-01

    We present numerical simulations of closed wavy Taylor vortices and of helicoidal wavy spirals in the Taylor-Couette system. These wavy structures appearing via a secondary bifurcation out of Taylor vortex flow and out of spiral vortex flow, respectively, mediate transitions between Taylor and spiral vortices and vice versa. Structure, dynamics, stability and bifurcation behaviour are investigated in quantitative detail as a function of Reynolds numbers and wave numbers for counter-rotating as well as corotating cylinders. These results are obtained by solving the Navier-Stokes equations subject to axial periodicity for a radius ratio η=0.5 with a combination of a finite differences method and a Galerkin method.

  11. Ablation acceleration of macroparticle in spiral magnetic fields

    International Nuclear Information System (INIS)

    Ikuta, Kazunari.

    1981-05-01

    The rocket motion of macroparticles heated by energetic pulses in a spiral magnetic field was studied. The purpose of the present work is to study the ablation acceleration of a macroparticle in a spiral magnetic field with the help of the law of conservation of angular momentum. The basic equation of motion of ablatively accelerated projectile in a spiral magnetic field was derived. Any rocket which is ejecting fully ionized plasma in an intense magnetic field with rotational transform is able to have spin by the law of conservation of momentum. The effect of spiral magnetic field on macroparticle acceleration is discussed. The necessary mass ratio increase exponentially with respect to the field parameter. The spiral field should be employed with care to have only to stabilize the position of macroparticles. As conclusion, it can be said that the ablation acceleration of the projectile in a spiral field can give the accelerated body spin quite easily. (Kato, T.)

  12. Mechanical response of spiral interconnect arrays for highly stretchable electronics

    KAUST Repository

    Qaiser, Nadeem

    2017-11-21

    A spiral interconnect array is a commonly used architecture for stretchable electronics, which accommodates large deformations during stretching. Here, we show the effect of different geometrical morphologies on the deformation behavior of the spiral island network. We use numerical modeling to calculate the stresses and strains in the spiral interconnects under the prescribed displacement of 1000 μm. Our result shows that spiral arm elongation depends on the angular position of that particular spiral in the array. We also introduce the concept of a unit-cell, which fairly replicates the deformation mechanism for full complex hexagon, diamond, and square shaped arrays. The spiral interconnects which are axially connected between displaced and fixed islands attain higher stretchability and thus experience the maximum deformations. We perform tensile testing of 3D printed replica and find that experimental observations corroborate with theoretical study.

  13. Optical and theoretical studies of giant clouds in spiral galaxies

    International Nuclear Information System (INIS)

    Elmegreen, B.G.; Elmegreen, D.M.

    1980-01-01

    An optical study of four spiral galaxies, combined with radiative transfer models for transmitted and scattered light, has led to a determination of the opacities and masses of numerous dark patches and dust lanes that outline spiral structure. The observed compression factors for the spiral-like dust lanes are in accord with expectations from the theory of gas flow in spiral density waves. Several low density (10 2 cm -3 ) clouds containing 10 6 to 10 7 solar masses were also studied. These results are discussed in terms of recent theoretical models of cloud and star formation in spiral galaxies. The long-term evolution of giant molecular clouds is shown to have important consequences for the positions and ages of star formation sites in spiral arms. (Auth.)

  14. Wave-particle dualism of spiral waves dynamics.

    Science.gov (United States)

    Biktasheva, I V; Biktashev, V N

    2003-02-01

    We demonstrate and explain a wave-particle dualism of such classical macroscopic phenomena as spiral waves in active media. That means although spiral waves appear as nonlocal processes involving the whole medium, they respond to small perturbations as effectively localized entities. The dualism appears as an emergent property of a nonlinear field and is mathematically expressed in terms of the spiral waves response functions, which are essentially nonzero only in the vicinity of the spiral wave core. Knowledge of the response functions allows quantitatively accurate prediction of the spiral wave drift due to small perturbations of any nature, which makes them as fundamental characteristics for spiral waves as mass is for the condensed matter.

  15. Mechanical response of spiral interconnect arrays for highly stretchable electronics

    KAUST Repository

    Qaiser, Nadeem; Khan, S. M.; Nour, Maha A.; Rehman, M. U.; Rojas, J. P.; Hussain, Muhammad Mustafa

    2017-01-01

    A spiral interconnect array is a commonly used architecture for stretchable electronics, which accommodates large deformations during stretching. Here, we show the effect of different geometrical morphologies on the deformation behavior of the spiral island network. We use numerical modeling to calculate the stresses and strains in the spiral interconnects under the prescribed displacement of 1000 μm. Our result shows that spiral arm elongation depends on the angular position of that particular spiral in the array. We also introduce the concept of a unit-cell, which fairly replicates the deformation mechanism for full complex hexagon, diamond, and square shaped arrays. The spiral interconnects which are axially connected between displaced and fixed islands attain higher stretchability and thus experience the maximum deformations. We perform tensile testing of 3D printed replica and find that experimental observations corroborate with theoretical study.

  16. Spiral: a new equipment for exotic nuclei; Spiral: un nouvel equipement pour les noyaux exotiques

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    This document presents the GANIL activities and more specially the SPIRAL project. The missions of the GANIL are to allow scientists fundamental researches in Nuclear Physics and to develop applications for heavy ions in other domains. Spiral is an european project, decided by NuPECC (NUclear Physics European Collaboration Committee). It is a first generation equipment allowing the production and the acceleration of light and moderately heavy nuclei at energy range of 2 to 25 MeV/nucleus. (A.L.B.)

  17. Nonlinear dynamics of breathers in the spiral structures of magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, V. V., E-mail: kiselev@imp.uran.ru; Raskovalov, A. A. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-06-15

    The structure and properties of pulsating solitons (breathers) in the spiral structures of magnets are analyzed within the sine-Gordon model. The breather core pulsations are shown to be accompanied by local shifts and oscillations of the spiral structure with the formation of “precursors” and “tails” in the moving soliton. The possibilities for the observation and excitation of breathers in the spiral structures of magnets and multiferroics are discussed.

  18. Compression of interstellar clouds in spiral density-wave shocks

    International Nuclear Information System (INIS)

    Woodward, P.R.

    1979-01-01

    A mechanism of triggering star formation by galactic shocks is discussed. The possibilty that shocks may form along spiral arms in the gaseous component of a galactic disk is by now a familiar feature of spiral wave theory. It was suggested by Roberts (1969) that these shocks could trigger star formation in narrow bands forming a coherent spiral pattern over most of the disk of a galaxy. Some results of computer simulations of such a triggering process for star formation are reported. (Auth.)

  19. Cochlea and other spiral forms in nature and art.

    Science.gov (United States)

    Marinković, Slobodan; Stanković, Predrag; Štrbac, Mile; Tomić, Irina; Ćetković, Mila

    2012-01-01

    The original appearance of the cochlea and the specific shape of a spiral are interesting for both the scientists and artists. Yet, a correlation between the cochlea and the spiral forms in nature and art has been very rarely mentioned. The aim of this study was to investigate the possible correlation between the cochlea and the other spiral objects in nature, as well as the artistic presentation of the spiral forms. We explored data related to many natural objects and examined 13,625 artworks created by 2049 artists. We also dissected 2 human cochleas and prepared histologic slices of a rat cochlea. The cochlea is a spiral, cone-shaped osseous structure that resembles certain other spiral forms in nature. It was noticed that parts of some plants are arranged in a spiral manner, often according to Fibonacci numbers. Certain animals, their parts, or their products also represent various types of spirals. Many of them, including the cochlea, belong to the logarithmic type. Nature created spiral forms in the living world to pack a larger number of structures in a limited space and also to improve their function. Because the cochlea and other spiral forms have a certain aesthetic value, many artists presented them in their works of art. There is a mathematical and geometric correlation between the cochlea and natural spiral objects, and the same functional reason for their formation. The artists' imagery added a new aspect to those domains. Obviously, the creativity of nature and Homo sapiens has no limits--like the infinite distal part of the spiral. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Diagnosis of pancreatic tumors by spiral angio CT

    International Nuclear Information System (INIS)

    Miura, Kohi; Nakao, Norio; Takayasu, Yukio; Okawa, Tomohisa

    1995-01-01

    Spiral angio were performed with injection of 30 ml of contrast material at a rate of 1 ml/sec with a scan delay of 6 sec through catheter into the celiac artery while the blood flow of the superior mesenteric artery (SMA) was occluded by the inflated balloon catheter. Spiral CT scans were obtained using Somatom Plus (Siemens). Parameter for spiral CT were 24-sec acquisition time, 5 mm collimation, 5 mm/sec table incrementation. Reconstructions were performed every 5 mm. Pancreatic cancers were characteristically depicted with spiral angio CT as hypodensity relative to normal enhanced pancreatic parenchyma. On dynamic angio CT studies performed in pancreatic cancers, the area of cancer and normal parenchyma had maximum level of enhancement at 10-15 sec after injection of contrast material via catheter into the celiac, and there was no difference in enhancement between tumor and normal parenchyma. On the other hand, the lesions of cancer were revealed as hypodensity with spiral angio CT. In case of chronic pancreatitis, the enhancement of the entire pancreas obtained with spiral angio CT was homogeneous. Insulinoma in the tail of pancreas was detected by spiral angio CT but was not detected by both selective angiography and conventional CT. Three-dimensional (3-D) rendering spiral angio CT data shows the extent of vascular involvement by pancreatic cancer and provides useful information for surgical planning. Spiral angio CT is the most useful procedure for diagnosis of pancreatic tumor. (author)

  1. SPIRAL2 Week 2012 - Slides of the presentations

    International Nuclear Information System (INIS)

    Staley, F.; Jacquemet, M.; Lewitowicz, M.; Bertrand, P.; Tuske, O.; Caruso, A.; Leyge, J.F.; Perrot, L.; Di Giacomo, M.; Ausset, P.; Moscatello, M.H.; Savalle, A.; Rannou, B.; Lambert, M.; Petit, E.; Hulin, X.; Barre-Boscher, N.; Tusseau-Nenez, S.; Tecchio, L.B.

    2013-01-01

    The main goal of the 5. edition of the SPIRAL2 Week is to present and discuss the current status of the SPIRAL2 project in front of a large community of scientists and engineers. The program of the meeting will include presentations on scientific and technical developments related to the baseline project, experiments and theory. The main topics to be discussed at the conference are: -) physics and detectors at SPIRAL2, -) driver accelerators, -) production of radioactive ion beams (RIB), -) safety, -) buildings and infrastructure, -) RIB facilities worldwide, and -) SPIRAL2 preparatory phase. This document is made up of the slides of the presentations

  2. Algorithms for computing efficient, electric-propulsion, spiralling trajectories

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop techniques for rapidly designing many-revolution, electric-propulsion, spiralling trajectories, including the effects of shadowing, gravity harmonics, and...

  3. On the nature of the ramified spiral structure of galaxies

    International Nuclear Information System (INIS)

    Mishurov, Yu.N.; Suchkov, A.A.

    1976-01-01

    The nature of large-scale branching of spiral arms observed in a number of galaxies has been explained in the framework of the density wave theory. The solutions of the dispersion equation of spiral waves of density relative to the wave number k(r) in the models of galaxies in the form of two discs rotating with different angular velocities have been shown to be branching functions of the parameter r (r is the galacto-centric distance) under definite conditions; it corresponds to the branching of spiral arms. Hydrodynamic and kinetic considerations are also presented. The last one makes possible the understanding several other structural properties of spiral galaxies

  4. Influence of excitability on unpinning and termination of spiral waves.

    Science.gov (United States)

    Luengviriya, Jiraporn; Sutthiopad, Malee; Phantu, Metinee; Porjai, Porramain; Kanchanawarin, Jarin; Müller, Stefan C; Luengviriya, Chaiya

    2014-11-01

    Application of electrical forcing to release pinned spiral waves from unexcitable obstacles and to terminate the rotation of free spiral waves at the boundary of excitable media has been investigated in thin layers of the Belousov-Zhabotinsky (BZ) reaction, prepared with different initial concentrations of H_{2}SO_{4}. Increasing [H_{2}SO_{4}] raises the excitability of the reaction and reduces the core diameter of free spiral waves as well as the wave period. An electric current with density stronger than a critical value Junpin causes a pinned spiral wave to drift away from the obstacle. For a given obstacle size, Junpin increases with [H_{2}SO_{4}]. Under an applied electrical current, the rotation center of a free spiral wave drifts along a straight path to the boundary. When the current density is stronger than a critical value Jterm, the spiral tip is forced to hit the boundary, where the spiral wave is terminated. Similar to Junpin for releasing a pinned spiral wave, Jterm also increases with [H_{2}SO_{4}]. These experimental findings were confirmed by numerical simulations using the Oregonator model, in which the excitability was adjusted via the ratio of the excitation rate to the recovery rate of the BZ reaction. Therefore, our investigation shows that decreasing the excitability can facilitate elimination of spiral waves by electrical forcing, either in the presence of obstacles or not.

  5. Emission Characteristics of Organic Light-Emitting Diodes and Organic Thin-Films with Planar and Corrugated Structures

    Directory of Open Access Journals (Sweden)

    Mao-Kuo Wei

    2010-04-01

    Full Text Available In this paper, we review the emission characteristics from organic light-emitting diodes (OLEDs and organic molecular thin films with planar and corrugated structures. In a planar thin film structure, light emission from OLEDs was strongly influenced by the interference effect. With suitable design of microcavity structure and layer thicknesses adjustment, optical characteristics can be engineered to achieve high optical intensity, suitable emission wavelength, and broad viewing angles. To increase the extraction efficiency from OLEDs and organic thin-films, corrugated structure with micro- and nano-scale were applied. Microstructures can effectively redirects the waveguiding light in the substrate outside the device. For nanostructures, it is also possible to couple out the organic and plasmonic modes, not only the substrate mode.

  6. Effects of corrugation shape on frequency band-gaps for longitudinal wave motion in a periodic elastic layer

    DEFF Research Database (Denmark)

    Sorokin, Vladislav

    2016-01-01

    The paper concerns determining frequency band-gaps for longitudinal wave motion in a periodic waveguide. The waveguide may be considered either as an elastic layer with variable thickness or as a rod with variable cross section. As a result, widths and locations of all frequency band-gaps are det......The paper concerns determining frequency band-gaps for longitudinal wave motion in a periodic waveguide. The waveguide may be considered either as an elastic layer with variable thickness or as a rod with variable cross section. As a result, widths and locations of all frequency band......, harmonic in the corrugation series. The revealed insights into the mechanism of band-gap formation can be used to predict locations and widths of all frequency band-gaps featured by any corrugation shape. These insights are general and can be valid also for other types of wave motion in periodic structures...

  7. An Experimental Study on the Shear Hysteresis and Energy Dissipation of the Steel Frame with a Trapezoidal-Corrugated Steel Plate.

    Science.gov (United States)

    Shon, Sudeok; Yoo, Mina; Lee, Seungjae

    2017-03-06

    The steel frame reinforced with steel shear wall is a lateral load resisting system and has higher strength and shear performance than the concrete shear wall system. Especially, using corrugated steel plates in these shear wall systems improves out-of-plane stiffness and flexibility in the deformation along the corrugation. In this paper, a cyclic loading test of this steel frame reinforced with trapezoidal-corrugated steel plate was performed to evaluate the structural performance. The hysteresis behavior and the energy dissipation capacity of the steel frame were also compared according to the corrugated direction of the plate. For the test, one simple frame model without the wall and two frame models reinforced with the plate are considered and designed. The test results showed that the model reinforced with the corrugated steel plate had a greater accumulated energy dissipation capacity than the experimental result of the non-reinforced model. Furthermore, the energy dissipation curves of two reinforced frame models, which have different corrugated directions, produced similar results.

  8. Three dimensional corrugated organic photovoltaics for building integration; improving the efficiency, oblique angle and diffuse performance of solar cells

    OpenAIRE

    Kettle, Jeff; Bristow, Noel; Sweet, Tracy K. N.; Jenkins, Nick; Benatto, Gisele Alves dos Reis; Jørgensen, Mikkel; Krebs, Frederik C

    2015-01-01

    The lamination of OPV modules to corrugated roof cladding has been undertaken. The 3-dimensional form of the cladding provides three advantages for outdoor OPV deployment; firstly the ‘footprint’ of the solar cell is reduced, which leads to B10% improved power conversion (PCE) efficiency per unit area. Secondly, the oblique angle performance is enhanced, leading to increased output in the early morning and evening. Indoor characterisation showed a 9-fold enhancement in efficiency was obtainab...

  9. A Unified Scaling Law in Spiral Galaxies.

    Science.gov (United States)

    Koda; Sofue; Wada

    2000-03-01

    We investigate the origin of a unified scaling relation in spiral galaxies. Observed spiral galaxies are spread on a plane in the three-dimensional logarithmic space of luminosity L, radius R, and rotation velocity V. The plane is expressed as L~&parl0;VR&parr0;alpha in the I passband, where alpha is a constant. On the plane, observed galaxies are distributed in an elongated region which looks like the shape of a surfboard. The well-known scaling relations L-V (Tully-Fisher [TF] relation), V-R (also the TF relation), and R-L (Freeman's law) can be understood as oblique projections of the surfboard-like plane into two-dimensional spaces. This unified interpretation of the known scaling relations should be a clue to understand the physical origin of all the relations consistently. Furthermore, this interpretation can also explain why previous studies could not find any correlation between TF residuals and radius. In order to clarify the origin of this plane, we simulate formation and evolution of spiral galaxies with the N-body/smoothed particle hydrodynamics method, including cooling, star formation, and stellar feedback. Initial conditions are set to 14 isolated spheres with two free parameters, such as mass and angular momentum. The cold dark matter (h=0.5, Omega0=1) cosmology is considered as a test case. The simulations provide the following two conclusions: (1) The slope of the plane is well reproduced but the zero point is not. This zero-point discrepancy could be solved in a low-density (Omega00.5) cosmology. (2) The surfboard-shaped plane can be explained by the control of galactic mass and angular momentum.

  10. New compact cyclotron design for SPIRAL

    International Nuclear Information System (INIS)

    Duval, M.; Bourgarel, M.P.; Ripouteau, F.

    1995-01-01

    The SPIRAL project whose purpose is the production and the acceleration of radioactive nuclei is under realization at GANIL. The new facility uses a cyclotron as post accelerator taking place behind the present machine. The magnet structure is made of 4 independent return yokes and a common circular pole piece (3.5 m in diameter) with 4 sectors. The average induction needed is 1.56 Tesla with hill and valley gaps of respectively 0.12 and 0.3 m. The required field patterns are adjusted by means of circular trim coils located between the sectors and the pole piece. (author)

  11. Spiral Light Beams and Contour Image Processing

    Science.gov (United States)

    Kishkin, Sergey A.; Kotova, Svetlana P.; Volostnikov, Vladimir G.

    Spiral beams of light are characterized by their ability to remain structurally unchanged at propagation. They may have the shape of any closed curve. In the present paper a new approach is proposed within the framework of the contour analysis based on a close cooperation of modern coherent optics, theory of functions and numerical methods. An algorithm for comparing contours is presented and theoretically justified, which allows convincing of whether two contours are similar or not to within the scale factor and/or rotation. The advantages and disadvantages of the proposed approach are considered; the results of numerical modeling are presented.

  12. Controls and automation in the SPIRAL project

    International Nuclear Information System (INIS)

    Bothner, U.; Boulot, A.; Maherault, J.; Martial, L.

    1999-01-01

    The control and automation team of the R and D of Accelerator-Exotic Beam Department has had in the framework of SPIRAL collaboration the following tasks: 1. automation of the resonator high frequency equipment of the CIME cyclotron; 2. automation of the vacuum equipment, i.e. the low energy line (TBE), the CIME cyclotron, the low energy line (BE); 3. automation of load safety for power supply; 4. for each of these tasks a circuitry file based on the SCHEMA software has been worked out. The programs required in the automation of load safety for power supply (STEP5, PROTOOL, DESIGNER 4.1) were developed and implemented for PC

  13. Production and post acceleration scheme for spiral

    International Nuclear Information System (INIS)

    Bibet, D.

    2001-01-01

    SPIRAL, the R.I.B. facility of GANIL uses heavy ion beams to produce radioactive atoms inside a thick target. Atoms are ionised in a compact permanent magnet ECR ion source. The compact cyclotron CIME accelerates the radioactive ions in an energy range from 1.7 to 25 MeV/u. The cyclotron acts as a mass separator with resolving power of 2500. Plastic scintillator and silicon detectors are used to tune the machine at a very low intensity. An overview of the facility, stable beam tests results and the R and D program will be presented. (authors)

  14. SPIRAL2/DESIR high resolution mass separator

    Energy Technology Data Exchange (ETDEWEB)

    Kurtukian-Nieto, T., E-mail: kurtukia@cenbg.in2p3.fr [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Baartman, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver B.C., V6T 2A3 (Canada); Blank, B.; Chiron, T. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Davids, C. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Delalee, F. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Duval, M. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); El Abbeir, S.; Fournier, A. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Lunney, D. [CSNSM-IN2P3-CNRS, Université de Paris Sud, F-91405 Orsay (France); Méot, F. [BNL, Upton, Long Island, New York (United States); Serani, L. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Stodel, M.-H.; Varenne, F. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); and others

    2013-12-15

    DESIR is the low-energy part of the SPIRAL2 ISOL facility under construction at GANIL. DESIR includes a high-resolution mass separator (HRS) with a designed resolving power m/Δm of 31,000 for a 1 π-mm-mrad beam emittance, obtained using a high-intensity beam cooling device. The proposed design consists of two 90-degree magnetic dipoles, complemented by electrostatic quadrupoles, sextupoles, and a multipole, arranged in a symmetric configuration to minimize aberrations. A detailed description of the design and results of extensive simulations are given.

  15. Temperature simulations for the SPIRAL ISOL target

    International Nuclear Information System (INIS)

    Maunoury, L.; Bajeat, O.; Lichtenthaler, R.; Villari, A.C.C.

    2001-01-01

    Simulations of the power deposition and target temperature distributions in the SPIRAL ISOL target are presented. These simulations consider different heavy-ion beams with intensities corresponding to 2 and 6 kW on a carbon target. A new solutions, which corresponds to the splitting of the production target into two parts, where the first is cooled and the second is heated, allows keeping the overall size of the target ensemble relatively small. An extrapolation of the considered target geometry to primary beam intensities up to 1 MW is also presented. (authors)

  16. Galaxy Zoo: dust in spiral galaxies star

    OpenAIRE

    Masters, Karen L.; Nichol, Robert; Bamford, Steven; Mosleh, Moein; Lintott, Chris J.; Andreescu, Dan; Edmondson, Edward M.; Keel, William C.; Murray, Phil; Raddick, M. Jordan; Schawinski, Kevin; Slosar, Anze; Szalay, Alexander S.; Thomas, Daniel; Vandenberg, Jan

    2010-01-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination dependence of optical colours for 24 276 well-resolved Sloan Digital Sky Survey (SDSS) galaxies visually classified via the Galaxy Zoo project. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4 mag for the ugri passbands (estimating 0.3 mag of extinction in z band). We split the sample into ‘bulgy’ (early-type) and ‘discy’ (late-typ...

  17. Experimental evaluation of the performances of cellulosic pads made out of Kraft and NSSC corrugated papers as evaporative media

    International Nuclear Information System (INIS)

    Barzegar, Mahsa; Layeghi, Mohammad; Ebrahimi, Ghanbar; Hamzeh, Yahya; Khorasani, Manouchehr

    2012-01-01

    Highlights: ► We experimentally evaluated the performances of cellulosic pads. ► A number of experiments have been done in a wind tunnel. ► The results showed that cooling efficiency improves with decrease of air velocity and flute size. ► Water consumption increases with the increase of air velocity. ► Cooling efficiency of various pads was also compared. - Abstract: The purpose of this study was to evaluate the performances of cellulosic pads made out of Kraft and NSSC corrugated papers in three flute sizes, experimentally. A number of experiments have been done in a wind tunnel in order to evaluate the cooling efficiency and water consumption as a function of air velocity. The tests were carried out at three levels of air velocity (1.8, 2.25, and 2.67 ms −1 ) for three flute sizes of Kraft and NSSC corrugated papers (2.5, 3.5, and 4.5 mm). Analysis of the results indicated that cooling efficiency improves with decrease of air velocity and flute size of corrugated papers; however, water consumption increases with the increase of air velocity. The results were compared with each other and it was shown that the cellulosic pad made out of Kraft paper with 2.5 mm flute size has the highest performance (92%) at 1.8 ms −1 air velocity in comparison with the other cellulosic pads.

  18. Trend extraction of rail corrugation measured dynamically based on the relevant low-frequency principal components reconstruction

    International Nuclear Information System (INIS)

    Li, Yanfu; Liu, Hongli; Ma, Ziji

    2016-01-01

    Rail corrugation dynamic measurement techniques are critical to guarantee transport security and guide rail maintenance. During the inspection process, low-frequency trends caused by rail fluctuation are usually superimposed on rail corrugation and seriously affect the assessment of rail maintenance quality. In order to extract and remove the nonlinear and non-stationary trends from original mixed signals, a hybrid model based ensemble empirical mode decomposition (EEMD) and modified principal component analysis (MPCA) is proposed in this paper. Compared with the existing de-trending methods based on EMD, this method first considers low-frequency intrinsic mode functions (IMFs) thought to be underlying trend components that maybe contain some unrelated components, such as white noise and low-frequency signal itself, and proposes to use PCA to accurately extract the pure trends from the IMFs containing multiple components. On the other hand, due to the energy contribution ratio between trends and mixed signals is prior unknown, and the principal components (PCs) decomposed by PCA are arranged in order of energy reduction without considering frequency distribution, the proposed method modifies traditional PCA and just selects relevant low-frequency PCs to reconstruct the trends based on the zero-crossing numbers (ZCN) of each PC. Extensive tests are presented to illustrate the effectiveness of the proposed method. The results show the proposed EEMD-PCA-ZCN is an effective tool for trend extraction of rail corrugation measured dynamically. (paper)

  19. Planet-driven Spiral Arms in Protoplanetary Disks. II. Implications

    Science.gov (United States)

    Bae, Jaehan; Zhu, Zhaohuan

    2018-06-01

    We examine whether various characteristics of planet-driven spiral arms can be used to constrain the masses of unseen planets and their positions within their disks. By carrying out two-dimensional hydrodynamic simulations varying planet mass and disk gas temperature, we find that a larger number of spiral arms form with a smaller planet mass and a lower disk temperature. A planet excites two or more spiral arms interior to its orbit for a range of disk temperatures characterized by the disk aspect ratio 0.04≤slant {(h/r)}p≤slant 0.15, whereas exterior to a planet’s orbit multiple spiral arms can form only in cold disks with {(h/r)}p≲ 0.06. Constraining the planet mass with the pitch angle of spiral arms requires accurate disk temperature measurements that might be challenging even with ALMA. However, the property that the pitch angle of planet-driven spiral arms decreases away from the planet can be a powerful diagnostic to determine whether the planet is located interior or exterior to the observed spirals. The arm-to-arm separations increase as a function of planet mass, consistent with previous studies; however, the exact slope depends on disk temperature as well as the radial location where the arm-to-arm separations are measured. We apply these diagnostics to the spiral arms seen in MWC 758 and Elias 2–27. As shown in Bae et al., planet-driven spiral arms can create concentric rings and gaps, which can produce a more dominant observable signature than spiral arms under certain circumstances. We discuss the observability of planet-driven spiral arms versus rings and gaps.

  20. SELF-DESTRUCTING SPIRAL WAVES: GLOBAL SIMULATIONS OF A SPIRAL-WAVE INSTABILITY IN ACCRETION DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jaehan; Hartmann, Lee [Department of Astronomy, University of Michigan, 1085 S. University Ave., Ann Arbor, MI 48109 (United States); Nelson, Richard P.; Richard, Samuel, E-mail: jaehbae@umich.edu, E-mail: lhartm@umich.edu, E-mail: r.p.nelson@qmul.ac.uk, E-mail: samuel.richard@qmul.ac.uk [Astronomy Unit, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2016-09-20

    We present results from a suite of three-dimensional global hydrodynamic simulations that shows that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport and vertical mixing at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter α ∼ 5 × 10{sup −4} in our reference model). The instability is found to operate in a wide range of disk models, including those with isothermal or adiabatic equations of state, and in viscous disks where the dimensionless kinematic viscosity ν ≤ 10{sup −5}. This robustness suggests that the instability will have applications to a broad range of astrophysical disk-related phenomena, including those in close binary systems, planets embedded in protoplanetary disks (including Jupiter in our own solar system) and FU Orionis outburst models. Further work is required to determine the nature of the instability and to evaluate its observational consequences in physically more complete disk models than we have considered in this paper.

  1. SELF-DESTRUCTING SPIRAL WAVES: GLOBAL SIMULATIONS OF A SPIRAL-WAVE INSTABILITY IN ACCRETION DISKS

    International Nuclear Information System (INIS)

    Bae, Jaehan; Hartmann, Lee; Nelson, Richard P.; Richard, Samuel

    2016-01-01

    We present results from a suite of three-dimensional global hydrodynamic simulations that shows that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport and vertical mixing at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter α ∼ 5 × 10 −4 in our reference model). The instability is found to operate in a wide range of disk models, including those with isothermal or adiabatic equations of state, and in viscous disks where the dimensionless kinematic viscosity ν ≤ 10 −5 . This robustness suggests that the instability will have applications to a broad range of astrophysical disk-related phenomena, including those in close binary systems, planets embedded in protoplanetary disks (including Jupiter in our own solar system) and FU Orionis outburst models. Further work is required to determine the nature of the instability and to evaluate its observational consequences in physically more complete disk models than we have considered in this paper.

  2. Sound Transmission Loss Through a Corrugated-Core Sandwich Panel with Integrated Acoustic Resonators

    Science.gov (United States)

    Schiller, Noah H.; Allen, Albert R.; Zalewski, Bart F; Beck, Benjamin S.

    2014-01-01

    The goal of this study is to better understand the effect of structurally integrated resonators on the transmission loss of a sandwich panel. The sandwich panel has facesheets over a corrugated core, which creates long aligned chambers that run parallel to the facesheets. When ports are introduced through the facesheet, the long chambers within the core can be used as low-frequency acoustic resonators. By integrating the resonators within the structure they contribute to the static load bearing capability of the panel while also attenuating noise. An analytical model of a panel with embedded resonators is derived and compared with numerical simulations. Predictions show that acoustic resonators can significantly improve the transmission loss of the sandwich panel around the natural frequency of the resonators. In one configuration with 0.813 m long internal chambers, the diffuse field transmission loss is improved by more than 22 dB around 104 Hz. The benefit is achieved with no added mass or volume relative to the baseline structure. The embedded resonators are effective because they radiate sound out-of-phase with the structure. This results in destructive interference, which leads to less transmitted sound power.

  3. Material selection for elastic energy absorption in origami-inspired compliant corrugations

    International Nuclear Information System (INIS)

    Tolman, Sean S; Delimont, Isaac L; Howell, Larry L; Fullwood, David T

    2014-01-01

    Elastic absorption of kinetic energy and distribution of impact forces are required in many applications. Recent attention to the potential for using origami in engineering may provide new methods for energy absorption and force distribution. A three-stage strategy is presented for selecting materials for such origami-inspired designs that can deform to achieve a desired motion without yielding, absorb elastic strain energy, and be lightweight or cost effective. Two material indices are derived to meet these requirements based on compliant mechanism theory. Finite element analysis is used to investigate the effects of the material stiffness in the Miura-ori tessellation on its energy absorption and force distribution characteristics compared with a triangular wave corrugation. An example is presented of how the method can be used to select a material for a general energy absorption application of the Miura-ori. Whereas the focus of this study is the Miura-ori tessellation, the methods developed can be applied to other tessellated patterns used in energy absorbing or force distribution applications. (paper)

  4. Disinfection of corrugated tubing by ozone and ultrasound in mechanically ventilated tracheostomized patients.

    Science.gov (United States)

    Lopes, M S; Ferreira, J R F; da Silva, K B; de Oliveira Bacelar Simplício, I; de Lima, C J; Fernandes, A B

    2015-08-01

    Medical equipment coming into contact with non-intact skin or mucous membranes is classified as semi-critical material. This equipment requires at least high-level disinfection, as the major risk in all invasive procedures is the introduction of pathogenic microbes causing hospital-associated infections. To evaluate the capacity of ozone gas and ultrasound to disinfect semi-critical, thermally sensitive material. Used corrugated tubing from mechanically ventilated tracheostomized patients in the intensive care unit was obtained. Enzymatic detergent was applied for 15min before different disinfection techniques were evaluated as follows: Group A (0.2% peracetic acid); Group B (ultrasound for 60min); Group C (application of ozone gas at a concentration of 33mg/L for 15min); Group D (ultrasound for 30min and ozone for 15min); Group E (ultrasound for 60min and ozone for 15min). Application of ultrasound for 60min reduced the level of microbial contamination by 4 log10, whereas ozone alone and the other two combined techniques (ultrasound and ozone) and the peracetic acid reduced the level of microbial contamination by 5 log10. Ozone was the most advantageous technique taking into consideration processing time, ease of use, effectiveness, and cost. The use of ozone gas to disinfect semi-critical material proved to be technically feasible and extremely promising. Copyright © 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  5. Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

    International Nuclear Information System (INIS)

    Ginzburg, N. S.; Zaslavsky, V. Yu.; Zotova, I. V.; Sergeev, A. S.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V.

    2015-01-01

    A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by “fresh” electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam

  6. High-power corrugates waveguide components for mm-wave fusion heating systems

    International Nuclear Information System (INIS)

    Olstad, R.A.; Doane, J.L.; Moeller, C.P.; O'Neill, R.C.; Di Martino, M.

    1996-10-01

    Considerable progress has been made over the last year in the U.S., Japan, Russia, and Europe in developing high power long pulse gyrotrons for fusion plasma heating and current drive. These advanced gyrotrons typically operate at a frequency in the range 82 GHz to 170 GHz at nearly megawatt power levels for pulse lengths up to 5 s. To take advantage of these new microwave sources for fusion research, new and improved transmission line components are needed to reliably transmit microwave power to plasmas with minimal losses. Over the last year, General Atomics and collaborating companies (Spinner GmbH in Europe and Toshiba Corporation in Japan) have developed a wide variety of new components which meet the demanding power, pulse length, frequency, and vacuum requirements for effective utilization of the new generation of gyrotrons. These components include low-loss straight corrugated waveguides, miter bends, miter bend polarizers, power monitors, waveguide bellows, de breaks, waveguide switches, dummy loads, and distributed windows. These components have been developed with several different waveguide diameters (32, 64, and 89 mm) and frequency ranges (82 GHz to 170 GHz). This paper describes the design requirements of selected components and their calculated and measured performance characteristics

  7. Spontaneous acoustic emission of a corrugated shock wave in the presence of a reflecting surface

    International Nuclear Information System (INIS)

    Wouchuk, J.G.; Lopez Cavada, J.

    2004-01-01

    An analytic model to study perturbation evolution in the space between a corrugated shock and a piston surface is presented. The conditions for stable oscillation patterns are obtained by looking at the poles of the exact Laplace transform. It is seen that besides the standard D'yakov-Kontorovich (DK) mode of oscillation, the shock surface can exhibit an additional finite set of discrete frequencies, due to the interaction with the piston which reflects sound waves from behind. The additional eigenmodes are excited when the shock is launched at t=0 + . The first eigenmode (the DK mode) is always present, if the Hugoniot curve has the correct slope in the V-p plane. However, the additional frequencies could be excited for strong enough shocks. The predictions of the model are verified for particular cases by studying a van der Waals gas, as in the work of Bates and Montgomery [Phys. Fluids 11, 462 (1999); Phys. Rev. Lett. 84, 1180 (2000)]. Only acoustic emission modes are considered

  8. The Fluid-Solid Interaction Dynamics between Underwater Explosion Bubble and Corrugated Sandwich Plate

    Directory of Open Access Journals (Sweden)

    Hao Wang

    2016-01-01

    Full Text Available Lightweight sandwich structures with highly porous 2D cores or 3D (three-dimensional periodic cores can effectively withstand underwater explosion load. In most of the previous studies of sandwich structure antiblast dynamics, the underwater explosion (UNDEX bubble phase was neglected. As the UNDEX bubble load is one of the severest damage sources that may lead to structure large plastic deformation and crevasses failure, the failure mechanisms of sandwich structures might not be accurate if only shock wave is considered. In this paper, detailed 3D finite element (FE numerical models of UNDEX bubble-LCSP (lightweight corrugated sandwich plates interaction are developed by using MSC.Dytran. Upon the validated FE model, the bubble shape, impact pressure, and fluid field velocities for different stand-off distances are studied. Based on numerical results, the failure modes of LCSP and the whole damage process are obtained. It is demonstrated that the UNDEX bubble collapse jet local load plays a more significant role than the UNDEX shock wave load especially in near-field underwater explosion.

  9. Quasi-phase-matched acceleration of electrons in a corrugated plasma channel

    Directory of Open Access Journals (Sweden)

    S. J. Yoon

    2012-08-01

    Full Text Available A laser pulse propagating in a corrugated plasma channel is composed of spatial harmonics whose phase velocities can be subluminal. The phase velocity of a spatial harmonic can be matched to the speed of a relativistic electron resulting in direct acceleration by the guided laser field in a plasma waveguide and linear energy gain over the interaction length. Here we examine the fully self-consistent interaction of the laser pulse and electron beam using particle-in-cell (PIC simulations. For low electron beam densities, we find that the ponderomotive force of the laser pulse pushes plasma channel electrons towards the propagation axis, which deflects the beam electrons. When the beam density is high, the space charge force of the beam drives the channel electrons off axis, providing collimation of the beam. In addition, we consider a ramped density profile for lowering the threshold energy for trapping in a subluminal spatial harmonic. By using a density ramp, the trapping energy for a normalized vector potential of a_{0}=0.1 is reduced from a relativistic factor γ_{0}=170 to γ_{0}=20.

  10. Natural Fiber Reinforced Composites: A Review on Potential for Corrugated Core of Sandwich Structures

    Directory of Open Access Journals (Sweden)

    Jusoh A.F.

    2016-01-01

    Full Text Available Natural fibers, characterized by sustainability, have gained a considerable attention in recent years, due to their advantages of environmental acceptability and commercial viability. In this paper, the characterization of natural fibers including the mechanical properties and alkalization of fibers is presented. Most recent study had gone through the mercerization process to improve the toughness of natural fibers; which is a well-known hydrophilic material. Traditional reinforcement method was commonly used to fabricate a natural fiber composite such as hand lay-up and mold press due to its convenience in terms of time and cost. Also, different kind of matrix material used in different kind of natural fibers gave high impact on the tensile and flexural test result. By selecting appropriate chemical treatment, matrix material and fabrication method, the tensile and flexural test gives different results and findings. As most researchers tend to use metals to create corrugated cores for sandwich structure, it is possible to develop this structure using natural fibers such as kenaf, wood dust, and other natural fibers.

  11. Corrugated paraffin nanocomposite films as large stroke thermal actuators and self-activating thermal interfaces.

    Science.gov (United States)

    Copic, Davor; Hart, A John

    2015-04-22

    High performance active materials are of rapidly growing interest for applications including soft robotics, microfluidic systems, and morphing composites. In particular, paraffin wax has been used to actuate miniature pumps, solenoid valves, and composite fibers, yet its deployment is typically limited by the need for external volume constraint. We demonstrate that compact, high-performance paraffin actuators can be made by confining paraffin within vertically aligned carbon nanotube (CNT) films. This large-stroke vertical actuation is enabled by strong capillary interaction between paraffin and CNTs and by engineering the CNT morphology by mechanical compression before capillary-driven infiltration of the molten paraffin. The maximum actuation strain of the corrugated CNT-paraffin films (∼0.02-0.2) is comparable to natural muscle, yet the maximum stress is limited to ∼10 kPa by collapse of the CNT network. We also show how a CNT-paraffin film can serve as a self-activating thermal interface that closes a gap when it is heated. These new CNT-paraffin film actuators could be produced by large-area CNT growth, infiltration, and lamination methods, and are attractive for use in miniature systems due to their self-contained design.

  12. Propulsion using the electron spiral toroid

    International Nuclear Information System (INIS)

    Seward, Clint

    1998-01-01

    A new propulsion method is proposed which could potentially reduce propellant needed for space travel by three orders of magnitude. It uses the newly patented electron spiral toroid (EST), which stores energy as magnetic field energy. The EST is a hollow toroid of electrons, all spiraling in parallel paths in a thin outer shell. The electrons satisfy the coupling condition, forming an electron matrix. Stability is assured as long as the coupling condition is satisfied. The EST is held in place with a small external electric field; without an external magnetic field. The EST system is contained in a vacuum chamber. The EST can be thought of as an energetic entity, with electrons at 10,000 electron volts. Propulsion would not use combustion, but would heat propellant through elastic collisions with the EST surface and eject them for thrust. Chemical rocket combustion heats propellant to 4000 deg. C; an EST will potentially heat the propellant 29,000 times as much, reducing propellant needs accordingly. The thrust can be turned ON and OFF. The EST can be recharged as needed

  13. Optimising imaging parameters in experimental spiral CT

    International Nuclear Information System (INIS)

    Tiitola, M.; Vehmas, T.; Kivisaari, R.P.; Kivisaari, L.

    1997-01-01

    Purpose: This in vitro study was conducted to analyse lesion detection and relative radiation exposure in different CT techniques. Material and Methods: We used a plastic phantom (12 x 8 x 2 cm) containing holes filled with air or fluid of varying densities to simulate lesions. This was imaged with Siemens Somatom Plus S and GE High Speed Advantage units. We varied table feeds (3 and 6 mm/s in Siemens and 3 and 4.5 mm/s in GE) and increments (2 mm and 4 mm) while keeping collimation at 3 mm. The SmartScan program of GE and the reformating algorithm of Siemens were also analysed. To evaluate the different methods, the phatnom lesions were counted by 3 observers. Radiation exposures associated with each technique were also measured. Results: The images reformatted to a coronal direction were significantly inferior (p<0.01) to those in other techniques. The use of SmartScan did not influence lesion detection, nor did changes in pitch or increment. Spiral and non-spiral techniques proved to be equal. Radiation exposure was lowest when a greater pitch or the SmartScan program was used. Conclusion: Radiation exposure in CT can be limited without significantly impairing the image quality by using low-dose techniques. Reformatting to a coronal direction should be used with care as it debases the image quality. (orig.)

  14. Spiral-shaped reactor for water disinfection

    KAUST Repository

    Soukane, Sofiane

    2016-04-20

    Chlorine-based processes are still widely used for water disinfection. The disinfection process for municipal water consumption is usually carried out in large tanks, specifically designed to verify several hydraulic and disinfection criteria. The hydrodynamic behavior of contact tanks of different shapes, each with an approximate total volume of 50,000 m3, was analyzed by solving turbulent momentum transport equations with a computational fluid dynamics code, namely ANSYS fluent. Numerical experiments of a tracer pulse were performed for each design to generate flow through curves and investigate species residence time distribution for different inlet flow rates, ranging from 3 to 12 m3 s−1. A new nature-inspired Conch tank design whose shape follows an Archimedean spiral was then developed. The spiral design is shown to strongly outperform the other tanks’ designs for all the selected plug flow criteria with an enhancement in efficiency, less short circuiting, and an order of magnitude improvement in mixing and dispersion. Moreover, following the intensification philosophy, after 50% reduction in its size, the new design retains its properties and still gives far better results than the classical shapes.

  15. Model for Spiral Galaxys Rotation Curves

    Science.gov (United States)

    Hodge, John

    2003-11-01

    A model of spiral galaxy dynamics is proposed. An expression describing the rotation velocity of particles v in a galaxy as a function of the distance from the center r (RC) is developed. The resulting, intrinsic RC of a galaxy is Keplerian in the inner bulge and rising in the disk region without modifying the Newtonian gravitational potential (MOND) and without unknown dark matter. The v^2 is linearly related to r of the galaxy in part of the rapidly rising region of the HI RC (RRRC) and to r^2 in another part of the RRRC. The r to discontinuities in the surface brightness versus r curve is related to the 21 cm line width, the measured mass of the central supermassive black hole (SBH), and the maximum v^2 in the RRRC. The distance to spiral galaxies can be calculated from these relationships that tightly correlates with the distance calculated using Cepheid variables. Differing results in measuring the mass of the SBH from differing measurement procedures are explained. This model is consistent with previously unexplained data, has predicted new relationships, and suggests a new model of the universe. Full text: http://web.infoave.net/ ˜scjh.

  16. Stellar complexes in spiral arms of galaxies

    Science.gov (United States)

    Efremov, Yu. N.

    The history of the introduction and development of the star complexes conception is briefly described. These large groups of stars were picked out and named as such ones in our Galaxy with argumentation and evidence for their physical unity (using the Cepheid variables the distances and ages of which are easy determined from their periods); anyway earlier the complexes were noted along the spiral arms of the Andromeda galaxy, but were not recognized as a new kind of star group. The chains of complexes along the spiral arms are observed quite rarely; their origin is explained by magneto- gravitational or purely gravitational instability developing along the arm. It is not clear why these chains are quite a rare phenomenon - and more so why sometimes the regular chain of complexes are observed in one arm only. Probably intergalactic magnetic field participated in formation of such chains. Apart from the complexes located along the arms, there are isolated giant complexes known (up to 700 pc in diameter) which look like super-gigantic but rather rarefied globular clusters. Until now only two of these formations are studied, in NGC 6946 and M51.

  17. Spiral blood flow in aorta-renal bifurcation models.

    Science.gov (United States)

    Javadzadegan, Ashkan; Simmons, Anne; Barber, Tracie

    2016-01-01

    The presence of a spiral arterial blood flow pattern in humans has been widely accepted. It is believed that this spiral component of the blood flow alters arterial haemodynamics in both positive and negative ways. The purpose of this study was to determine the effect of spiral flow on haemodynamic changes in aorta-renal bifurcations. In this regard, a computational fluid dynamics analysis of pulsatile blood flow was performed in two idealised models of aorta-renal bifurcations with and without flow diverter. The results show that the spirality effect causes a substantial variation in blood velocity distribution, while causing only slight changes in fluid shear stress patterns. The dominant observed effect of spiral flow is on turbulent kinetic energy and flow recirculation zones. As spiral flow intensity increases, the rate of turbulent kinetic energy production decreases, reducing the region of potential damage to red blood cells and endothelial cells. Furthermore, the recirculation zones which form on the cranial sides of the aorta and renal artery shrink in size in the presence of spirality effect; this may lower the rate of atherosclerosis development and progression in the aorta-renal bifurcation. These results indicate that the spiral nature of blood flow has atheroprotective effects in renal arteries and should be taken into consideration in analyses of the aorta and renal arteries.

  18. A comment on spiral motions in projective relativity

    International Nuclear Information System (INIS)

    Muzzio, J.C.; Lousto, C.O.; Instituto de Astronomia y Fisica del Espacio de la Republica Argentina)

    1985-01-01

    Astronomical evidence has been inadequately invoked to support projective relativity. The spiral structure cannot be explained just by the existence of spiral orbits, and the use of Oort's constant to support the theory is also a misunderstanding. Besides, some mathematical inaccuracies make the application invalid. (author)

  19. Drift of Spiral Waves in Complex Ginzburg-Landau Equation

    International Nuclear Information System (INIS)

    Yang Junzhong; Zhang Mei

    2006-01-01

    The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg-Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomenological theory to explain the observations.

  20. Strained spiral vortex model for turbulent fine structure

    Science.gov (United States)

    Lundgren, T. S.

    1982-01-01

    A model for the intermittent fine structure of high Reynolds number turbulence is proposed. The model consists of slender axially strained spiral vortex solutions of the Navier-Stokes equation. The tightening of the spiral turns by the differential rotation of the induced swirling velocity produces a cascade of velocity fluctuations to smaller scale. The Kolmogorov energy spectrum is a result of this model.

  1. Nonuniqueness of self-propagating spiral galaxy models

    International Nuclear Information System (INIS)

    Freedman, W.L.; Madore, B.F.

    1984-01-01

    We demonstrate the nonuniqueness of the basic assumptions leading to spiral structure in self-propagating star formation models. Even in the case where star formation occurs purely spontaneously and does not propagate, we have generated spiral structure by adopting the radically different assumption where star formation is systematically inhibited

  2. A Fundamental Plane of Spiral Structure in Disk Galaxies

    NARCIS (Netherlands)

    Davis, Benjamin L.; Kennefick, Daniel; Kennefick, Julia; Westfall, Kyle B.; Shields, Douglas W.; Flatman, Russell; Hartley, Matthew T.; Berrier, Joel C.; Martinsson, Thomas P. K.; Swaters, Rob A.

    Spiral structure is the most distinctive feature of disk galaxies and yet debate persists about which theory of spiral structure is correct. Many versions of the density wave theory demand that the pitch angle be uniquely determined by the distribution of mass in the bulge and disk of the galaxy. We

  3. Profiles of the stochastic star formation process in spiral galaxies

    International Nuclear Information System (INIS)

    Comins, N.

    1981-01-01

    The formation of spiral arms in disc galaxies is generally attributed to the effects of spiral density waves. These relatively small (i.e. 5 per cent) non-axisymmetric perturbations of the interstellar medium cause spiral arms highlighted by O and B type stars to be created. In this paper another mechanism for spiral arm formation, the stochastic self-propagating star formation (SSPSF) process is examined. The SSPSF process combines the theory that shock waves from supernovae will compress the interstellar medium to create new stars, some of which will be massive enough to also supernova, with a disc galaxy's differential rotation to create spiral arms. The present work extends this process to the case where the probability of star formation from supernova shocks decreases with galactic radius. Where this work and previous investigations overlap (namely the uniform probability case), the agreement is very good, pretty spirals with various numbers of arms are generated. The decreasing probability cases, taken to vary as rsup(-j), still form spiral arms for 0 1.5 the spiral structure is essentially non-existent. (author)

  4. The cold interstellar medium - An HI view of spiral galaxies

    NARCIS (Netherlands)

    Sancisi, R; Bender, R; Davies, RL

    1996-01-01

    An HI view of spiral galaxies is presented. In the first part the standard picture of isolated, normal spiral galaxies is briefly reviewed. In the second part attention is drawn to all those phenomena, such as tidal interactions, accretion and mergers, that depend on the galaxy environment and seem

  5. Star formation and the surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.

    1985-01-01

    The (blue) surface brightness of spiral galaxies is significantly correlated with their Hα linewidth. This can be most plausibly interpreted as a correlation of surface brightness with star formation rate. There is also a significant difference in surface brightness between galaxies forming stars in a grand design spiral pattern and those with floc star formation regions. (author)

  6. Up the Down Spiral with English: Guidelines, Project Insight.

    Science.gov (United States)

    Catholic Board of Education, Diocese of Cleveland, OH.

    This curriculum guide presents the philosophy, objectives, and processes which unify a student-centered English program based on Jerome Bruner's concept of the spiral curriculum. To illustrate the spiraling of the learning process (i.e., engagement, perception, interpretation, evaluation, and personal integration), the theme of "hero" is traced…

  7. Topographic Beta Spiral and Onshore Intrusion of the Kuroshio Current

    Science.gov (United States)

    Yang, De-Zhou; Huang, Rui Xin; Yin, Bao-shu; Feng, Xing-Ru; Chen, Hai-ying; Qi, Ji-Feng; Xu, Ling-jing; Shi, Yun-long; Cui, Xuan; Gao, Guan-Dong; Benthuysen, Jessica A.

    2018-01-01

    The Kuroshio intrusion plays a vitally important role in carrying nutrients to marginal seas. However, the key mechanism leading to the Kuroshio intrusion remains unclear. In this study we postulate a mechanism: when the Kuroshio runs onto steep topography northeast of Taiwan, the strong inertia gives rise to upwelling over topography, leading to a left-hand spiral in the stratified ocean. This is called the topographic beta spiral, which is a major player regulating the Kuroshio intrusion; this spiral can be inferred from hydrographic surveys. In the world oceans, the topographic beta spirals can be induced by upwelling generated by strong currents running onto steep topography. This is a vital mechanism regulating onshore intruding flow and the cross-shelf transport of energy and nutrients from the Kuroshio Current to the East China Sea. This topographic beta spiral reveals a long-term missing link between the oceanic general circulation theory and shelf dynamic theory.

  8. Spatial and mass distributions of molecular clouds and spiral structure

    International Nuclear Information System (INIS)

    Kwan, J.; Valdes, F.; National Optical Astronomy Observatories, Tucson, AZ)

    1987-01-01

    The growth of molecular clouds resulting from cloud-cloud collisions and coalescence in the Galactic ring between 4 and 8 kpc are modeled, taking into account the presence of a spiral potential and the mutual cloud-cloud gravitational attraction. The mean lifetime of molecular clouds is determined to be about 200 million years. The clouds are present in both spiral arm and interarm regions, but a spiral pattern in their spatial distribution is clearly discernible, with the more massive clouds showing a stronger correlation with the spiral arms. As viewed from within the Galactic disk, however, it is very difficult to ascertain that the molecular cloud distribution in longitude-velocity space has a spiral pattern. 19 references

  9. Suppression of Spiral Wave in Modified Orengonator Model

    International Nuclear Information System (INIS)

    Ma Jun; Wang Chunni; Jin Wuyin; Yi Ming

    2008-01-01

    In this paper, a spatial perturbation scheme is proposed to suppress the spiral wave in the modified Orengonator model, which is used to describe the chemical reaction in the light-sensitive media. The controllable external illumination Φ is perturbed with a spatial linear function. In our numerical simulation, the scheme is investigated by imposing the external controllable illumination on the space continuously and/or intermittently. The numerical simulation results confirm that the stable rotating spiral wave still can be removed with the scheme proposed in this paper even if the controllable Φ changed vs. time and space synchronously. Then the scheme is also used to control the spiral wave and turbulence in the modified Fitzhugh-Nagumo model. It is found that the scheme is effective to remove the sable rotating and meandering spiral wave but it costs long transient period and intensity of the gradient parameter to eliminate the spiral turbulence

  10. Neutral hydrogen and spiral structure in M33

    International Nuclear Information System (INIS)

    Newton, K.

    1980-01-01

    Observations of neutral hydrogen (H I) in the galaxy M33 are presented which have sufficient angular resolution (47 x 93 arcsec) to distinguish detailed H I spiral structure for the first time. H I spiral features extend over the entire disc; the pattern is broken and multi-armed with the best-defined arms lying at radii outside the brightest optical features. Several very narrow spiral 'filaments' are unresolved by the beam, implying true widths -1 , is perturbed near the inner spiral arms. These perturbations agree with the predictions of density-wave theory but may simply arise from the self-gravity of massive arms whether or not they are a quasi-stationary wave phenomenon. If the outer spiral features form a rigidly rotating density-wave pattern, the absence of large radial streaming motions along the features implies a small pattern speed ( -1 kpc -1 ), with corotation in the outer parts of the disc. (author)

  11. A FUNDAMENTAL PLANE OF SPIRAL STRUCTURE IN DISK GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Benjamin L.; Kennefick, Daniel; Kennefick, Julia; Shields, Douglas W. [Arkansas Center for Space and Planetary Sciences, University of Arkansas, 346 1/2 North Arkansas Avenue, Fayetteville, AR 72701 (United States); Westfall, Kyle B. [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, NL-9700 AV Groningen (Netherlands); Flatman, Russell [School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332 (United States); Hartley, Matthew T. [Department of Physics, University of Arkansas, 226 Physics Building, 835 West Dickson Street, Fayetteville, AR 72701 (United States); Berrier, Joel C. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Martinsson, Thomas P. K. [Leiden Observatory, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Swaters, Rob A., E-mail: bld002@email.uark.edu [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

    2015-03-20

    Spiral structure is the most distinctive feature of disk galaxies and yet debate persists about which theory of spiral structure is correct. Many versions of the density wave theory demand that the pitch angle be uniquely determined by the distribution of mass in the bulge and disk of the galaxy. We present evidence that the tangent of the pitch angle of logarithmic spiral arms in disk galaxies correlates strongly with the density of neutral atomic hydrogen in the disk and with the central stellar bulge mass of the galaxy. These three quantities, when plotted against each other, form a planar relationship that we argue should be fundamental to our understanding of spiral structure in disk galaxies. We further argue that any successful theory of spiral structure must be able to explain this relationship.

  12. Imaging of head and neck tumors -- methods: CT, spiral-CT, multislice-spiral-CT

    International Nuclear Information System (INIS)

    Baum, Ulrich; Greess, Holger; Lell, Michael; Noemayr, Anton; Lenz, Martin

    2000-01-01

    Spiral-CT is standard for imaging neck tumors. In correspondence with other groups we routinely use spiral-CT with thin slices (3 mm), a pitch of 1.3-1.5 and an overlapping reconstruction increment (2-3 mm). In patients with dental fillings a short additional spiral parallel to the corpus of the mandible reduces artifacts behind the dental arches and improves the diagnostic value of CT. For the assessment of the base of the skull, the orbital floor, the palate and paranasal sinuses an additional examination in the coronal plane is helpful. Secondary coronal reconstructions of axial scans are helpful in the evaluation of the crossing of the midline by small tumors of the tongue base or palate. For an optimal vascular or tissue contrast a sufficient volume of contrast medium and a start delay greater than 70-80 s are necessary. In our opinion the best results can be achieved with a volume of 150 ml, a flow of 2.5 ml/s and a start delay of 80 s. Dynamic enhanced CT is only necessary in some special cases. There is clear indication for dynamic enhanced CT where a glomus tumor is suspected. Additional functional CT imaging during i-phonation and/or Valsalva's maneuver are of great importance to prove vocal cords mobility. Therefore, imaging during i-phonation is an elemental part of every thorough examination of the hypopharynx and larynx region. Multislice-spiral-CT allows almost isotropic imaging of the head and neck region and improves the assessment of tumor spread and lymph node metastases in arbitrary oblique planes. Thin structures (the base of the skull, the orbital floor, the hard palate) as well as the floor of the mouth can be evaluated sufficiently with multiplanar reformations. Usually, additional coronal scanning is not necessary with multislice-spiral-CT. Multislice-spiral-CT is especially advantageous in defining the critical relationships of tumor and lymph node metastases and for functional imaging of the hypopharynx and larynx not only in the

  13. Pathomorphism of spiral tibial fractures in computed tomography imaging.

    Science.gov (United States)

    Guzik, Grzegorz

    2011-01-01

    Spiral fractures of the tibia are virtually homogeneous with regard to their pathomorphism. The differences that are seen concern the level of fracture of the fibula, and, to a lesser extent, the level of fracture of the tibia, the length of fracture cleft, and limb shortening following the trauma. While conventional radiographs provide sufficient information about the pathomorphism of fractures, computed tomography can be useful in demonstrating the spatial arrangement of bone fragments and topography of soft tissues surrounding the fracture site. Multiple cross-sectional computed tomography views of spiral fractures of the tibia show the details of the alignment of bone chips at the fracture site, axis of the tibial fracture cleft, and topography of soft tissues that are not visible on standard radiographs. A model of a spiral tibial fracture reveals periosteal stretching with increasing spiral and longitudinal displacement. The cleft in tibial fractures has a spiral shape and its line is invariable. Every spiral fracture of both crural bones results in extensive damage to the periosteum and may damage bellies of the long flexor muscle of toes, flexor hallucis longus as well as the posterior tibial muscle. Computed tomography images of spiral fractures of the tibia show details of damage that are otherwise invisible on standard radiographs. Moreover, CT images provide useful information about the spatial location of the bone chips as well as possible threats to soft tissues that surround the fracture site. Every spiral fracture of the tibia is associated with disruption of the periosteum. 1. Computed tomography images of spiral fractures of the tibia show details of damage otherwise invisible on standard radiographs, 2. The sharp end of the distal tibial chip can damage the tibialis posterior muscle, long flexor muscles of the toes and the flexor hallucis longus, 3. Every spiral fracture of the tibia is associated with disruption of the periosteum.

  14. Spiral model pilot project information model

    Science.gov (United States)

    1991-01-01

    The objective was an evaluation of the Spiral Model (SM) development approach to allow NASA Marshall to develop an experience base of that software management methodology. A discussion is presented of the Information Model (IM) that was used as part of the SM methodology. A key concept of the SM is the establishment of an IM to be used by management to track the progress of a project. The IM is the set of metrics that is to be measured and reported throughout the life of the project. These metrics measure both the product and the process to ensure the quality of the final delivery item and to ensure the project met programmatic guidelines. The beauty of the SM, along with the IM, is the ability to measure not only the correctness of the specification and implementation of the requirements but to also obtain a measure of customer satisfaction.

  15. SPIRAL 2 RFQ Prototype First Tests

    CERN Document Server

    Ferdinand, Robin; Congretel, G; Curtoni, Aline; Delferriere, Olivier; Di Giacomo, Marco; France, Alain; Leboeuf, Didier; Thinel, Jean; Toussaint, Jean-Christian

    2005-01-01

    The SPIRAL2 RFQ is designed to accelerate at 88MHz two kinds of charge-over-mass ratio, Q/A, particles. The proposed injector can accelerate a 5 mA deuteron beam (Q/A=1/2) or a 1 mA particles beam with q/A=1/3 up to 0.75 MeV/A. It is a CW machine which has to show stable operation, provide the request availability, have the minimum losses in order to minimize the activation constraints and show the best quality/cost ratio. The prototype of this 4-vane RFQ has been built and tested. It allowed to verify the mechanical assembly concept (RFQ without any brazing step). The full power was easily injected in the cavity, with no concerns for the RF joints. The paper describes the different achievements.

  16. Fluid flow in a spiral microfluidic duct

    Science.gov (United States)

    Harding, Brendan; Stokes, Yvonne

    2018-04-01

    We consider the steady, pressure driven flow of a viscous fluid through a microfluidic device having the geometry of a planar spiral duct with a slowly varying curvature and height smaller than width. For this problem, it is convenient to express the Navier-Stokes equations in terms of a non-orthogonal coordinate system. Then, after applying appropriate scalings, the leading order equations admit a relatively simple solution in the central region of the duct cross section. First-order corrections with respect to the duct curvature and aspect ratio parameters are also obtained for this region. Additional correction terms are needed to ensure that no slip and no penetration conditions are satisfied on the side walls. Our solutions allow for a top wall shape that varies with respect to the radial coordinate which allows us to study the flow in a variety of cross-sectional shapes, including trapezoidal-shaped ducts that have been studied experimentally. At leading order, the flow is found to depend on the local height and slope of the top wall within the central region. The solutions are compared with numerical approximations of a classical Dean flow and are found to be in good agreement for a small duct aspect ratio and a slowly varying and small curvature. We conclude that the slowly varying curvature typical of spiral microfluidic devices has a negligible impact on the flow in the sense that locally the flow does not differ significantly from the classical Dean flow through a duct having the same curvature.

  17. An air-based corrugated cavity-receiver for solar parabolic trough concentrators

    International Nuclear Information System (INIS)

    Bader, Roman; Pedretti, Andrea; Barbato, Maurizio; Steinfeld, Aldo

    2015-01-01

    Highlights: • We analyze a novel tubular cavity-receiver for solar parabolic trough collectors. • Four-fold solar concentration ratio is reached compared to conventional receivers. • Efficient operation at up to 500 °C is possible. • The pumping power requirement is found to be acceptably low. - Abstract: A tubular cavity-receiver that uses air as the heat transfer fluid is evaluated numerically using a validated heat transfer model. The receiver is designed for use on a large-span (9 m net concentrator aperture width) solar parabolic trough concentrator. Through the combination of a parabolic primary concentrator with a nonimaging secondary concentrator, the collector reaches a solar concentration ratio of 97.5. Four different receiver configurations are considered, with smooth or V-corrugated absorber tube and single- or double-glazed aperture window. The collector’s performance is characterized by its optical efficiency and heat loss. The optical efficiency is determined with the Monte Carlo ray-tracing method. Radiative heat exchange inside the receiver is calculated with the net radiation method. The 2D steady-state energy equation, which couples conductive, convective, and radiative heat transfer, is solved for the solid domains of the receiver cross-section, using finite-volume techniques. Simulations for Sevilla/Spain at the summer solstice at solar noon (direct normal solar irradiance: 847 W m −2 , solar incidence angle: 13.9°) yield collector efficiencies between 60% and 65% at a heat transfer fluid temperature of 125 °C and between 37% and 42% at 500 °C, depending on the receiver configuration. The optical losses amount to more than 30% of the incident solar radiation and constitute the largest source of energy loss. For a 200 m long collector module operated between 300 and 500 °C, the isentropic pumping power required to pump the HTF through the receiver is between 11 and 17 kW

  18. An InP/Si heterojunction photodiode fabricated by self-aligned corrugated epitaxial lateral overgrowth

    International Nuclear Information System (INIS)

    Sun, Y. T.; Omanakuttan, G.; Lourdudoss, S.

    2015-01-01

    An n-InP/p-Si heterojunction photodiode fabricated by corrugated epitaxial lateral overgrowth (CELOG) method is presented. N-InP/p-Si heterojunction has been achieved from a suitable pattern containing circular shaped openings in a triangular lattice on the InP seed layer on p-Si substrate and subsequent CELOG of completely coalesced n-InP. To avoid current path through the seed layer in the final photodiode, semi-insulating InP:Fe was grown with adequate thickness prior to n-InP growth in a low pressure hydride vapor phase epitaxy reactor. The n-InP/p-Si heterointerface was analyzed by scanning electron microscopy and Raman spectroscopy. Room temperature cross-sectional photoluminescence (PL) mapping illustrates the defect reduction effect in InP grown on Si by CELOG method. The InP PL intensity measured above the InP/Si heterojunction is comparable to that of InP grown on a native planar substrate indicating low interface defect density of CELOG InP despite of 8% lattice mismatch with Si. The processed n-InP/p-Si heterojunction photodiodes show diode characteristics from the current-voltage (I-V) measurements with a dark current density of 0.324 mA/cm 2 at a reverse voltage of −1 V. Under the illumination of AM1.5 conditions, the InP/Si heterojunction photodiode exhibited photovoltaic effect with an open circuit voltage of 180 mV, a short circuit current density of 1.89 mA/cm 2 , an external quantum efficiency of 4.3%, and an internal quantum efficiency of 6.4%. This demonstration of epitaxially grown InP/Si heterojunction photodiode will open the door for low cost and high efficiency solar cells and photonic integration of III-Vs on silicon

  19. White-Light Emission and Structural Distortion in New Corrugated Two-Dimensional Lead Bromide Perovskites.

    Science.gov (United States)

    Mao, Lingling; Wu, Yilei; Stoumpos, Constantinos C; Wasielewski, Michael R; Kanatzidis, Mercouri G

    2017-03-29

    Hybrid inorganic-organic perovskites are developing rapidly as high performance semiconductors. Recently, two-dimensional (2D) perovskites were found to have white-light, broadband emission in the visible range that was attributed mainly to the role of self-trapped excitons (STEs). Here, we describe three new 2D lead bromide perovskites incorporating a series of bifunctional ammonium dications as templates which also emit white light: (1) α-(DMEN)PbBr 4 (DMEN = 2-(dimethylamino)ethylamine), which adopts a unique corrugated layered structure in space group Pbca with unit cell a = 18.901(4) Å, b = 11.782(2) Å, and c = 23.680(5) Å; (2) (DMAPA)PbBr 4 (DMAPA = 3-(dimethylamino)-1-propylamine), which crystallizes in P2 1 /c with a = 10.717(2) Å, b = 11.735(2) Å, c = 12.127(2) Å, and β = 111.53(3)°; and (3) (DMABA)PbBr 4 (DMABA = 4-dimethylaminobutylamine), which adopts Aba2 with a = 41.685(8) Å, b = 23.962(5) Å, and c = 12.000(2) Å. Photoluminescence (PL) studies show a correlation between the distortion of the "PbBr 6 " octahedron in the 2D layer and the broadening of PL emission, with the most distorted structure having the broadest emission (183 nm full width at half-maximum) and longest lifetime (τ avg = 1.39 ns). The most distorted member α-(DMEN)PbBr 4 exhibits white-light emission with a color rendering index (CRI) of 73 which is similar to a fluorescent light source and correlated color temperature (CCT) of 7863 K, producing "cold" white light.

  20. Theory of potentiostatic current transients for coupled catalytic reaction at random corrugated fractal electrode

    International Nuclear Information System (INIS)

    Jha, Shailendra K.; Kant, Rama

    2010-01-01

    We developed a mathematical model for the first order homogeneous catalytic chemical reaction coupled with an electron transfer (EC') on a rough working electrode. Results are obtained for the various roughness models of electrode corrugations, viz., (i) roughness as an exact periodic function, (ii) roughness as a random function with known statistical properties, and (iii) roughness as a random function with statistical self-affine fractality over a finite range of length scales. Method of Green's function is used in the formulation to obtain second-order perturbation (in roughness profile) expressions for the concentration, the local current density and the current transients. A general operator structure between these quantities and arbitrary roughness profile is emphasized. The statistically averaged (randomly rough) electrode response is obtained by an ensemble averaging over all possible surface configurations. An elegant mathematical formula between the average electrochemical current transient and surface structure factor or power-spectrum of roughness is obtained. This formula is used to obtain an explicit equation for the current on an approximately self-affine (or realistic) fractal electrode with a limited range of length scales of irregularities. This description of realistic fractal is obtained by cutoff power law power-spectrum of roughness. The realistic fractal power-spectrum consists of four physical characteristics, viz., the fractal dimension (D H ), lower (l) and upper (L) cutoff length scales of fractality and a proportionality factor (μ), which is related to the topothesy or strength of fractality. Numerical calculations are performed on final results to understand the effect of catalytic reaction and fractal morphological characteristics on potentiostatic current transients.

  1. Reversal of neuromuscular block with sugammadex: a comparison of the corrugator supercilii and adductor pollicis muscles in a randomized dose-response study.

    Science.gov (United States)

    Yamamoto, S; Yamamoto, Y; Kitajima, O; Maeda, T; Suzuki, T

    2015-08-01

    Neuromuscular monitoring using the corrugator supercilii muscle is associated with a number of challenges. The aim of this study was to assess reversal of a rocuronium-induced neuromuscular blockade with sugammadex according to monitoring either using the corrugator supercilii muscle or the adductor pollicis muscle. We hypothesized that a larger dose of sugammadex would be required to obtain a train-of-four (TOF) ratio of 1.0 with the corrugator supercilii muscle than with the adductor pollicis muscle. Forty patients aged 20-60 years and 40 patients aged ≥ 70 years were enrolled. After induction of anesthesia, we recorded the corrugator supercilii muscle response to facial nerve stimulation and the adductor pollicis muscle response to ulnar nerve stimulation using acceleromyography. All patients received 1 mg/kg rocuronium. When the first twitch (T1) of TOF recovered to 10% of control values at the corrugator supercilii, rocuronium infusion was commenced to maintain a T1 of 10% of the control at the corrugator supercilii. Immediately after discontinuation of rocuronium infusion, 2 mg/kg or 4 mg/kg of sugammadex was administered. The time for recovery to a TOF ratio of 1.0 and the number of patients not reaching a TOF ratio of 1.0 by 5 min at each dose and muscle was recorded. When neuromuscular block at the corrugator supercilii was maintained at a T1 of 10% of control, that at the adductor pollicis was deep (post-tetanic count ≤ 5). Sugammadex 4 mg/kg completely antagonized neuromuscular block at both muscles within 5 min. The time to a TOF ratio of 1.0 at the adductor pollicis was significantly longer in the group ≥ 70 years than the group 20-60 years (mean (SD): 178 (42.8) s vs. 120 (9.4) s, P sugammadex reversed neuromuscular blockade at the corrugator supercilii but not at the adductor pollicis, with 10 patients in the group 20-60 years and 8 patients in the group ≥ 70 years requiring an additional sugammadex (P

  2. Magnetization reversal in ferromagnetic spirals via domain wall motion

    Science.gov (United States)

    Schumm, Ryan D.; Kunz, Andrew

    2016-11-01

    Domain wall dynamics have been investigated in a variety of ferromagnetic nanostructures for potential applications in logic, sensing, and recording. We present a combination of analytic and simulated results describing the reliable field driven motion of a domain wall through the arms of a ferromagnetic spiral nanowire. The spiral geometry is capable of taking advantage of the benefits of both straight and circular wires. Measurements of the in-plane components of the spirals' magnetization can be used to determine the angular location of the domain wall, impacting the magnetoresistive applications dependent on the domain wall location. The spirals' magnetization components are found to depend on the spiral parameters: the initial radius and spacing between spiral arms, along with the domain wall location. The magnetization is independent of the parameters of the rotating field used to move the domain wall, and therefore the model is valid for current induced domain wall motion as well. The speed of the domain wall is found to depend on the frequency of the rotating driving field, and the domain wall speeds can be reliably varied over several orders of magnitude. We further demonstrate a technique capable of injecting multiple domain walls and show the reliable and unidirectional motion of domain walls through the arms of the spiral.

  3. Galaxy Zoo: constraining the origin of spiral arms

    Science.gov (United States)

    Hart, Ross E.; Bamford, Steven P.; Keel, William C.; Kruk, Sandor J.; Masters, Karen L.; Simmons, Brooke D.; Smethurst, Rebecca J.

    2018-05-01

    Since the discovery that the majority of low-redshift galaxies exhibit some level of spiral structure, a number of theories have been proposed as to why these patterns exist. A popular explanation is a process known as swing amplification, yet there is no observational evidence to prove that such a mechanism is at play. By using a number of measured properties of galaxies, and scaling relations where there are no direct measurements, we model samples of SDSS and S4G spiral galaxies in terms of their relative halo, bulge and disc mass and size. Using these models, we test predictions of swing amplification theory with respect to directly measured spiral arm numbers from Galaxy Zoo 2. We find that neither a universal cored or cuspy inner dark matter profile can correctly predict observed numbers of arms in galaxies. However, by invoking a halo contraction/expansion model, a clear bimodality in the spiral galaxy population emerges. Approximately 40 per cent of unbarred spiral galaxies at z ≲ 0.1 and M* ≳ 1010M⊙ have spiral arms that can be modelled by swing amplification. This population display a significant correlation between predicted and observed spiral arm numbers, evidence that they are swing amplified modes. The remainder are dominated by two-arm systems for which the model predicts significantly higher arm numbers. These are likely driven by tidal interactions or other mechanisms.

  4. Propagation of spiral waves pinned to circular and rectangular obstacles.

    Science.gov (United States)

    Sutthiopad, Malee; Luengviriya, Jiraporn; Porjai, Porramain; Phantu, Metinee; Kanchanawarin, Jarin; Müller, Stefan C; Luengviriya, Chaiya

    2015-05-01

    We present an investigation of spiral waves pinned to circular and rectangular obstacles with different circumferences in both thin layers of the Belousov-Zhabotinsky reaction and numerical simulations with the Oregonator model. For circular objects, the area always increases with the circumference. In contrast, we varied the circumference of rectangles with equal areas by adjusting their width w and height h. For both obstacle forms, the propagating parameters (i.e., wavelength, wave period, and velocity of pinned spiral waves) increase with the circumference, regardless of the obstacle area. Despite these common features of the parameters, the forms of pinned spiral waves depend on the obstacle shapes. The structures of spiral waves pinned to circles as well as rectangles with the ratio w/h∼1 are similar to Archimedean spirals. When w/h increases, deformations of the spiral shapes are observed. For extremely thin rectangles with w/h≫1, these shapes can be constructed by employing semicircles with different radii which relate to the obstacle width and the core diameter of free spirals.

  5. KEMAMPUAN GENTENG PLASTIK BERGELOMBANG (CORRUGATED PLASTIC SEBAGAI BIOFILTER PARTIKEL AMONIAK DAN BAHAN ORGANIK DI MEDIA BUDIDAYA DAN LIMBAH CAIR BUDIDAYA IKAN (Performance of Corrugated Plastic as Biofilter of Ammonia Particle and Organic Material

    Directory of Open Access Journals (Sweden)

    Muslim Muslim

    2010-07-01

    Full Text Available ABSTRAK Pertumbuhan budidaya ikan dalam beberapa dekade ini berkembang sangat pesat, hal ini karena permintaan akan ikan meningkat. Meningkatnya kegiatan budidaya ikan selalu diiringi dengan meningkatnya limbah yang dihasilkan. Hal ini akan sangat cepat berpengaruh bila sistem budidaya yang dipakai adalah semi intesif atau intensif. Limbah tersebut harus segera dihilangkan atau dikurangi, karena akan berdampak pada ikan yang dibudidaya dan lingkungan seperti sungai dan laut. Tujuan penelitian ini adalah ingin mengetahui kemampuan genteng plastik bergelombang mengurangi limbah yang dihasilkan budidaya ikan yaitu Total Suspended Sediment (TSS, Suspended Sediment (SS, amoniak dan bahan organik (COD. Dari hasil penelitian diperoleh bahwa air limbah budidaya ikan yang mengandung TSS, SS, amoniak dan bahan organik setelah dilewatkan dengan genteng plastik bergelombang konsentrasinya menurun dengan tingkat efisiensi pengurangan yang terjadi di dalam kolam ikan dan di luar kolam ikan adalah sebagai berikut: 74,51% dan 54,42% (TSS; 39,20% dan 49,12% (SS; 19,82% dan 14,2% (amoniak; dan 24,82% dan 22,47% (COD. Ternyata genteng plastik bergelombang mempunyai tingkat pengurangan (g/m3/hr dan tingkat pengurangan spesifik (mg/m2/hr terhadap kandungan amoniak lebih efektif bila dibandingkan dengan material lain seperti plastic rolls, scrub pads, pipa PVC dan lain sebagainya.   ABSTRACT Aquaculture has been developing rapidly during the last few decades; it is due to the increase of fish demand. Increasing aquaculture activities especially with semi-intensive and intensive system have significant effect on waste production, which has to be removed or to be reduced quickly because will effect on fish in rearing tank and environment when through away to environment such as river and sea. The objectives of this study were to know the capability of corrugated plastic to remove or to reduce wastes content produced by aquaculture activities, i.e, Total Suspended

  6. The effect of pitch in multislice spiral/helical CT

    International Nuclear Information System (INIS)

    Wang, G.; Vannier, M.W.

    2000-01-01

    The purpose of this study is to understand the effect of pitch on raw data interpolation in multislice spiral/helical computed tomography (CT) and provide guidelines for scanner design and protocol optimization. Multislice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the detector collimation, and the table increment per x-ray source rotation. The pitch in multislice spiral CT is defined as the ratio of the table increment over the detector collimation in this study. In parallel to the current framework for studying longitudinal image resolution, the central fan-beam rays of direct and opposite directions are considered, assuming a narrow cone-beam angle. Generally speaking, sampling in the Radon domain by the direct and opposite central rays is nonuniform along the longitudinal axis. Using a recently developed methodology for quantifying the sensibility of signal reconstruction from non-uniformly sampled finite points, the effect of pitch on raw data interpolation is analyzed in multislice spiral CT. Unlike single-slice spiral CT, in which image quality decreases monotonically as the pitch increases, the sensibility of raw data interpolation in multislice spiral CT increases, suggesting that image quality does not decrease monotonically in this case. The most favorable pitch can be found from the sensitivity-slice spiral CT is provided. The study on the effect of pitch using the sensitivity analysis approach reveals the fundamental characteristics of raw data interpolation in multislice spiral CT, and gives insights into interaction between pitch and image quality. These results may be valuable for design of multislice spiral CT scanners and imaging protocol optimization in clinical applications. (authors)

  7. Fabrication techniques of X-ray spiral zone plates

    International Nuclear Information System (INIS)

    Gao Nan; Zhu Xiaoli; Li Hailiang; Xie Changqing

    2010-01-01

    The techniques to make X-ray spiral zone plates using electron beam and X-ray lithography were studied. A master mask was fabricated on polyimide membrane by E-beam lithography and micro-electroplating. Spiral zone plates were efficiently replicated by X-ray lithography and micro-electroplating. By combining the techniques, spiral zone plates at 1 keV were successfully fabricate. With an outermost zone width of the 200 nm, and the gold absorbers thickness of 700 nm, the high quality zone plates can be used for X-ray phase contrast microscopy.(authors)

  8. Comments on H. Arp 'The persistent problem of spiral galaxies'

    International Nuclear Information System (INIS)

    Alfven, H.

    1987-04-01

    In his paper 'The persistent problem of Spiral Galaxies' H. Arp criticises the standard theory of spiral galaxies and demonstrates that introduction of plasma theory is necessary in order to understand the structure of spiral galaxies. In the present paper arguments are given in support of Arp's theory and suggestions are made how Arp's ideas should be developed. An important result of Arp's new approach is that there is no convincing argument for the belief that there is a 'missing mass'. This is important from a cosmological point of view. (author)

  9. A Software Development Simulation Model of a Spiral Process

    Science.gov (United States)

    Mizell, Carolyn; Malone, Linda

    2007-01-01

    There is a need for simulation models of software development processes other than the waterfall because processes such as spiral development are becoming more and more popular. The use of a spiral process can make the inherently difficult job of cost and schedule estimation even more challenging due to its evolutionary nature, but this allows for a more flexible process that can better meet customers' needs. This paper will present a discrete event simulation model of spiral development that can be used to analyze cost and schedule effects of using such a process in comparison to a waterfall process.

  10. Investigation on filter method for smoothing spiral phase plate

    Science.gov (United States)

    Zhang, Yuanhang; Wen, Shenglin; Luo, Zijian; Tang, Caixue; Yan, Hao; Yang, Chunlin; Liu, Mincai; Zhang, Qinghua; Wang, Jian

    2018-03-01

    Spiral phase plate (SPP) for generating vortex hollow beams has high efficiency in various applications. However, it is difficult to obtain an ideal spiral phase plate because of its continuous-varying helical phase and discontinued phase step. This paper describes the demonstration of continuous spiral phase plate using filter methods. The numerical simulations indicate that different filter method including spatial domain filter, frequency domain filter has unique impact on surface topography of SPP and optical vortex characteristics. The experimental results reveal that the spatial Gaussian filter method for smoothing SPP is suitable for Computer Controlled Optical Surfacing (CCOS) technique and obtains good optical properties.

  11. Flexible Engineering Structures from the Corrugated Metal Sheets - Comparison of Costs of Solutions used in the Road Building

    Science.gov (United States)

    Ołdakowska, E.

    2017-11-01

    The flexible structures from the corrugated metal sheets are used in particular in the road building, especially as passages for animals. Easy and quick assembly, as well as lower realization costs when compared to the traditional solutions increase interest in such structures. Availability and variety of systems allows for searching for solutions which are the best and optimal in the economical range. The article presents the comparison of costs of the basic materials used in various systems of flexible structures from the corrugated metal sheets. In order to determine the costs of the material solutions the data for two systems used in Poland (for construction of the upper passages for animals) since 2008 have been used. The cost estimation for the basic materials required for realization of 1 m2 of the flexible structure from the corrugated steel sheets have been prepared with use of prices obtained directly from the Polish contractors and manufacturers, as well as process included in the quarterly information (Sekocenbud). The difference of prices of materials available on the market allows the investor for selecting the structure depending on the needs and financial possibilities, as well as for achieving some savings. The savings in case of purchasing sheets of identical parameters (thickness, profile characteristics) are from approx. 4% to 8% per 1 m2 of sheet. The connectors in form of bolts M20 cl. 8.8 of various lengths are an expense from 3.00 PLN to 3.50 PLN. Those values may seem low, but taking into consideration amounts connected with construction of many square meters of structure they may become very important factor in the total investment costs.

  12. Elimination of spiral chaos by periodic force for the Aliev-Panfilov model

    OpenAIRE

    Sakaguchi, Hidetsugu; Fujimoto, Takefumi

    2003-01-01

    Spiral chaos appears in the two dimensional Aliev-Panfilov model. The generation mechanism of the spiral chaos is related to the breathing instability of pulse trains. The spiral chaos can be eliminated by applying periodic force uniformly. The elimination of spiral chaos is most effective, when the frequency of the periodic force is close to that of the breathing motion.

  13. Software trends for both the GANIL and spiral control

    International Nuclear Information System (INIS)

    David, L.; Lecorche, E.

    1999-01-01

    The Ganil facility has been running with a new control system since 1993. Many improvements have been done since that time to bring new capabilities to the system. So, in February 1996, when the Spiral control system was designed, it was mainly considered as an extension of the Ganil control system. This paper briefly recalls the basic architecture of the whole control system and the main choices upon which it relies. Then it presents the new software trends, to show how the Spiral control system has been integrated alongside the existing one. The last part describe the new developments and the most significant functionalities it brings as seen from the operator point of view, with some emphasis about the application programs for beam tuning. Indeed, these new programs have to be provided both for the spiral tuning with exotic ions beams and for the coupling of the Spiral and older Ganil facilities. (authors)

  14. Density wave theory and the classification of spiral galaxies

    International Nuclear Information System (INIS)

    Roberts, W.W. Jr.; Roberts, M.S.; Shu, F.H.

    1975-01-01

    Axisymmetric models of disk galaxies taken together with the density wave theory allow us to distinguish and categorize spiral galaxies by means of two fundamental galactic parameters: the total mass of the galaxy, divided by a characteristic dimension; and the degree of concentration of mass toward the galactic center. These two parameters govern the strength of the galactic shocks in the interstellar gas and the geometry of the spiral wave pattern. In turn, the shock strength and the theoretical pitch angle of the spiral arms play a major role in determining the degree of development of spiral structure in a galaxy and its Hubble type. The application of these results to 24 external galaxies demonstrates that the categorization of galaxies according to this theoretical framework correlates well with the accepted classification of these galaxies within the observed sequences of luminosity class and Hubble type

  15. The Clinical Learning Spiral: A Model to Develop Reflective Practitioners.

    Science.gov (United States)

    Stockhausen, Lynette

    1994-01-01

    The Clinical Learning Spiral incorporates reflective processes into undergraduate nursing education. It entails successive cycles of four phases: preparative (briefing, planning), constructive (practice development), reflective (debriefing), and reconstructive (planning for change and commitment to action). (SK)

  16. A model of the formation of spiral galaxies

    International Nuclear Information System (INIS)

    Brown, W.K.; Gritzo, L.A.

    1980-01-01

    It has been verified that the analytical results in a previous article for elliptical galaxies may also be used to describe spiral galaxies. Exploration of the model for small values of the principal parameter THETA yields surface mass density distributions as functions of radius which, while always displaying the exponential disk, describe both of the subcategories of spiral galaxies. Within the constraints of the model, the two main questions concerning spirals posed some years ago by Freeman appear to be successfully addressed. An intrinsic model mechanism has been identified that could account for the extended state of elliptical galaxies, as opposed to the flat disks of spirals. In general, the model correctly describes the relative sizes of the various types of galaxies. (orig.)

  17. Origin choice and petal loss in the flower garden of spiral wave tip trajectories

    OpenAIRE

    Gray, Richard A.; Wikswo, John P.; Otani, Niels F.

    2009-01-01

    Rotating spiral waves have been observed in numerous biological and physical systems. These spiral waves can be stationary, meander, or even degenerate into multiple unstable rotating waves. The spatiotemporal behavior of spiral waves has been extensively quantified by tracking spiral wave tip trajectories. However, the precise methodology of identifying the spiral wave tip and its influence on the specific patterns of behavior remains a largely unexplored topic of research. Here we use a two...

  18. Scintigraphic diagnosis of spiral fracture in young children

    International Nuclear Information System (INIS)

    Hossein-Foucher, C.; Venel, H.; Lecouffe, P.; Ythier, H.; Legghe, R.; Marchandise, X.

    1988-01-01

    8 cases of unsuspected bone fracture in children, identified at bone scan are reported. Common features were the children's young age (1 to 3 years), the absence of clinical suspicion, the initially normal X-rays, the fracture type (spiral fracture of the tibia undisplaced), and the uniform appearance of the bone scan. These data confim the value of bone scan in limping children and suggest that spiral fracture of the tibia is a frequent and underdiagnosed condition in children [fr

  19. Observational effects of explosions in the nuclei of spiral galaxies

    International Nuclear Information System (INIS)

    Sanders, R.H.; Bania, T.M.

    1976-01-01

    We conclude that an explosive event will produce a distinct observational signature evidenced by an inner ringlike structure of the principal spiral tracers, conspicuous dips in the gas rotation curve at the locus of this ring, and a ringlike or double radio structure in the plane of the galaxy. Evidence is presented supporting the suggestion that one particular spiral galaxy, NGC 4736, exhibits this characteristic signature and therefore is a galaxy which may have undergone a recent explosive event in its nucleus

  20. Digitized Spiral Drawing: A Possible Biomarker for Early Parkinson's Disease.

    Science.gov (United States)

    San Luciano, Marta; Wang, Cuiling; Ortega, Roberto A; Yu, Qiping; Boschung, Sarah; Soto-Valencia, Jeannie; Bressman, Susan B; Lipton, Richard B; Pullman, Seth; Saunders-Pullman, Rachel

    2016-01-01

    Pre-clinical markers of Parkinson's Disease (PD) are needed, and to be relevant in pre-clinical disease, they should be quantifiably abnormal in early disease as well. Handwriting is impaired early in PD and can be evaluated using computerized analysis of drawn spirals, capturing kinematic, dynamic, and spatial abnormalities and calculating indices that quantify motor performance and disability. Digitized spiral drawing correlates with motor scores and may be more sensitive in detecting early changes than subjective ratings. However, whether changes in spiral drawing are abnormal compared with controls and whether changes are detected in early PD are unknown. 138 PD subjects (50 with early PD) and 150 controls drew spirals on a digitizing tablet, generating x, y, z (pressure) data-coordinates and time. Derived indices corresponded to overall spiral execution (severity), shape and kinematic irregularity (second order smoothness, first order zero-crossing), tightness, mean speed and variability of spiral width. Linear mixed effect adjusted models comparing these indices and cross-validation were performed. Receiver operating characteristic analysis was applied to examine discriminative validity of combined indices. All indices were significantly different between PD cases and controls, except for zero-crossing. A model using all indices had high discriminative validity (sensitivity = 0.86, specificity = 0.81). Discriminative validity was maintained in patients with early PD. Spiral analysis accurately discriminates subjects with PD and early PD from controls supporting a role as a promising quantitative biomarker. Further assessment is needed to determine whether spiral changes are PD specific compared with other disorders and if present in pre-clinical PD.

  1. A Software Development Simulation Model of a Spiral Process

    OpenAIRE

    Carolyn Mizell; Linda Malone

    2009-01-01

    This paper will present a discrete event simulation model of a spiral development lifecycle that can be used to analyze cost and schedule effects of using such a process in comparison to a waterfall process. There is a need for simulation models of software development processes other than the waterfall due to new processes becoming more widely used in order to overcome the limitations of the traditional waterfall lifecycle. The use of a spiral process can make the inherently difficult job of...

  2. The accelerated ISOL technique and the SPIRAL project

    International Nuclear Information System (INIS)

    Villari, A.C.C.

    2001-01-01

    The accelerated ISOL technique is presented as an introduction to the present status of the SPIRAL facility. SPIRAL is based on the very high intensity light and heavy ion beams available at GANIL. The facility will deliver radioactive beams with energies in the range between 1.7 A and 25 A MeV. The presently target-ion source production system, as well the new developments undertaken by the target ion-source group at GANIL are presented. (authors)

  3. Lung studies with spiral CT. pitch 1 versus pitch 2

    International Nuclear Information System (INIS)

    Sartoni Galloni, S.; Miceli, M.; Lipparino, M.; Burzi, M.; Gigli, F.; Rossi, M.S.; Santoli, G.; Guidarelli, G.

    1999-01-01

    In Spiral CT, the pitch is the ratio of the distance to tabletop travels per 360 degrees rotation to nominal slice width, expressed in mm. Performing Spiral CT examination with pitch 2 allows to reduce examination time, exposure and contrast dose, and X-ray tube overload. The authors investigated the yield of pitch 2 in lung parenchyma studies, particular relative to diagnostic image quality [it

  4. Synchronizing spiral waves in a coupled Rössler system

    International Nuclear Information System (INIS)

    Gao Jia-Zhen; Yang Shu-Xin; Xie Ling-Ling; Gao Ji-Hua

    2011-01-01

    The synchronisation of spiral patterns in a drive-response Rössler system is studied. The existence of three types of synchronisation is revealed by inspecting the coupling parameter space. Two transient stages of phase synchronisation and partial synchronisation are observed in a comparatively weak feedback coupling parameter regime, whilst complete synchronisation of spirals is found with strong negative couplings. Detailed observations of the synchronous process, such as oscillatory frequencies, parameters mismatches and amplitude variations, etc, are investigated via numerical simulations. (general)

  5. Experimental investigation of laminar flow of viscous oil through a circular tube having integral axial corrugation roughness and fitted with twisted tapes with oblique teeth

    Science.gov (United States)

    Pal, Sagnik; Saha, Sujoy Kumar

    2015-08-01

    The experimental friction factor and Nusselt number data for laminar flow of viscous oil through a circular duct having integral axial corrugation roughness and fitted with twisted tapes with oblique teeth have been presented. Predictive friction factor and Nusselt number correlations have also been presented. The thermohydraulic performance has been evaluated. The major findings of this experimental investigation are that the twisted tapes with oblique teeth in combination with integral axial corrugation roughness perform significantly better than the individual enhancement technique acting alone for laminar flow through a circular duct up to a certain value of fin parameter.

  6. CHARACTERISTICS OF SPIRAL ARMS IN LATE-TYPE GALAXIES

    International Nuclear Information System (INIS)

    Honig, Z. N.; Reid, M. J.

    2015-01-01

    We have measured the positions of large numbers of H II regions in four nearly face-on, late-type, spiral galaxies: NGC 628 (M74), NGC 1232, NGC 3184, and NGC 5194 (M51). Fitting log-periodic spiral models to segments of each arm yields local estimates of spiral pitch angle and arm width. While pitch angles vary considerably along individual arms, among arms within a galaxy, and among galaxies, we find no systematic trend with galactocentric distance. We estimate the widths of the arm segments from the scatter in the distances of the H II regions from the spiral model. All major arms in these galaxies show spiral arm width increasing with distance from the galactic center, similar to the trend seen in the Milky Way. However, in the outermost parts of the galaxies, where massive star formation declines, some arms reverse this trend and narrow. We find that spiral arms often appear to be composed of segments of ∼5 kpc length, which join to form kinks and abrupt changes in pitch angle and arm width; these characteristics are consistent with properties seen in the large N-body simulations of D'Onghia et al. and others

  7. High-Tc Superconducting Thick-Film Spiral Magnet: Development and Characterization of a Single Spiral Module

    National Research Council Canada - National Science Library

    McGinnis, W

    1997-01-01

    The objective of this project was to make characterized and numerically model prototype modules of a new type of superconducting electromagnet based on stacked spirals of superconducting thick films...

  8. Reflection and refraction of elastic waves at a corrugated interface in a bi-material transversely isotropic full-space

    International Nuclear Information System (INIS)

    Shad-Manamen, N.; Eskandari-Ghadi, M.

    2008-01-01

    The existing theory for wave propagation through a soil layer are not compatible with the real soil layers because in the theory the layers are flat and the sub-layers are parallel, while in real the soil layers are not flat and they may not be parallel. Thus, wave propagations through a corrugated interface are so important. In this paper, a two dimensional SH-wave propagation through a corrugated interface between two linear transversely isotropic half-spaces is assessed. In order to do this, Lord Rayleigh's method is accepted to express the non-flat surface by a Fourier series. In this way, the amplitude of the reflected and transmitted waves is analytically determined in terms of the incident SH-wave amplitude. It is shown that except for the regular reflected and refracted waves, some irregular reflected and refracted waves are exist, and the amplitudes of these waves vary in terms of the angle and frequency of incident wave, equation of surface, and the material properties of the domains. The numerical computations for some cases of different amplitude/wave-length ratio of the interface are done. This work is an extension of Asano's paper (1960) for a more complicated interface, where more non-zero coefficients are considered in expressing the equation of surface in the form of Fourier series. The analytical results for some simpler case of isotropic domain are collapsed on Asano's results (1960). In addition, the numerical evaluation is in good agreement with Asano's.

  9. Evaluation of Fatigue Strength Improvement by CFRP Laminates and Shot Peening onto the Tension Flanges Joining Corrugated SteelWebs

    Directory of Open Access Journals (Sweden)

    Zhi-Yu Wang

    2015-08-01

    Full Text Available Corrugated steel web with inherent high out-of-plane stiffness has a promising application in configuring large span highway bridge girders. Due to the irregularity of the configuration details, the local stress concentration poses a major fatigue problem for the welded flange plates of high strength low alloy structural steels. In this work, the methods of applying CFRP laminate and shot peening onto the surfaces of the tension flanges were employed with the purpose of improving the fatigue strength of such configuration details. The effectiveness of this method in the improvement of fatigue strength has been examined experimentally. Test results show that the shot peening significantly increases hardness and roughness in contrast to these without treatment. Also, it has beneficial effects on the fatigue strength enhancement when compared against the test data of the joints with CFRP strengthening. The stiffness degradation during the loading progress is compared with each treatment. Incorporating the stress acting on the constituent parts of the CFRP laminates, a discussion is made regarding the mechanism of the retrofit and related influencing factors such as corrosion and economic cost. This work could enhance the understanding of the CFRP and shot peening in repairing such welded details and shed light on the reinforcement design of welded joints between corrugated steel webs and flange plates.

  10. A neutron beam facility at Spiral-2

    Energy Technology Data Exchange (ETDEWEB)

    Ledoux, X.; Bauge, E.; Belier, G.; Ethvignot, T.; Taieb, J.; Varignon, C. [CEA Bruyeres-le-Chatel, DIF, 91 (France); Andriamonje, S.; Dore, D.; Dupont, E.; Gunsing, F.; Ridikas, D.; Takibayev, A. [CEA Saclay, DSM/IRFU/SPhN, 91 - Gif-sur-Yvette (France); Blideanu, V. [CEA Saclay, DSM/IRFU/Senac, 91 - Gif-sur-Yvette (France); Aiche, M.; Barreau, G.; Czajkowski, S.; Jurado, B. [Centre d' Etudes Nucleaires de Bordeaux Gradignan, 33 (France); Ban, G.; Lecolley, F.R.; Lecolley, J.F.; Lecouey, J.L.; Marie, N.; Steckmeyer, J.C. [LPC, 14 - Caen (France); Dessagne, P.; Kerveno, M.; Rudolf, G. [IPHC, 57 - Strasbourg (France); Bem, P.; Mrazek, J.; Novak, J. [NPI, Rez (Czech Republic); Blomgren, J.; Pomp, S. [Uppsala Univ., Dept. of Physics and Astronomy (Sweden); Fischer, U.; Herber, S.; Simakov, S.P. [FZK, Karlsruhe (Germany); Jacquot, B.; Rejmund, F. [GANIL, 14 - Caen (France); Avrigeanu, M.; Avrigeanu, V.; Borcea, C.; Negoita, F.; Petrascu, M. [NIPNE, Bucharest (Romania); Oberstedt, S.; Plompen, A.J.M. [JRC/IRMM, Geel (Belgium); Shcherbakov, O. [PNPI, Gatchina (Russian Federation); Fallot, M. [Subatech, 44 - Nantes (France); Smith, A.G.; Tsekhanovich, I. [Manchester Univ., Dept. of Physics and Astronomy (United Kingdom); Serot, O.; Sublet, J.C. [CEA Cadarache, DEN, 13 - Saint-Paul-lez-Durance (France); Perrot, L.; Tassan-Got, L. [IPNO, 91 - Orsay (France); Caillaud, T.; Giot, L.; Landoas, O.; Ramillon, J.M.; Rosse, B.; Thfoin, I. [CIMAP, 14 - Caen (France); Balanzat, E.; Bouffard, S.; Guillous, S.; Oberstedt, A. [Orebro Univ. (Sweden)

    2009-07-01

    The future Spiral-2 facility, dedicated to the production of intense radioactive ion beams, is based on a high-power superconducting driver Linac, delivering high-intensity deuteron, proton and heavy ion beams. These beams are particularly well suited to the production of neutrons in the 100 keV- 40 MeV energy range, a facility called 'Neutrons for Science' (NFS) will be built in the LINAG Experimental Area (LEA). NFS, operational in 2012, will be composed of a pulsed neutron beam for in-flight measurements and irradiation stations for activation measurements and material studies. Thick C and Be converters and a deuteron beam will produce an intense continuous neutron spectrum, while a thin {sup 7}Li target and a proton beam allow to generate quasi-mono-energetic neutrons. In the present work we show how the primary ion beam characteristics (energy, time resolution and intensity) are adequate to create a neutron time-of-flight facility delivering intense neutron fluxes in the 100 keV-40 MeV energy range. Irradiation stations for neutron, proton and deuteron reactions will also allow to perform cross-section measurements by means of the activation technique. Light-ion beams will be used to study radiation damage effects on materials for the nuclear industry. (authors)

  11. Galactic spiral arms formed by central explosions

    International Nuclear Information System (INIS)

    Havnes, O.

    1978-01-01

    Calculations have been made of spiral arm formation due to central explosions in a nucleus surrounded by a disc containing most of the galactic mass with the purpose of obtaining estimates on lifetimes of arms and the requirements on the energy involved in the process. The ejected gas is taken to be a few percent, or less, of the central nucleus and is ejected with velocities of the order of 1000 km s -1 . The gas, considered to be in forms of blobs, moves under the gravitational force from the disc and the nucleus and the drag force by the gas in the disc. The orbits of the blobs evolve towards the circular orbits of the disc due to this drag force and the velocities in the arms will therefore, after some time, approach those of a normal rotation curve. A relatively open structure will last 8 years. Stable ring structures with longer lifetimes may be formed by some explosions. With an energy of approximately 5 x 10 57 erg in the initial gas-blob motion and a duration of the explosion of approximately 10 7 years, the energy output in such explosions has to be > 10 43 erg s -1 . (Auth.)

  12. Flocculent and grand design spiral galaxies in groups: time scales for the persistence of grand design spiral structures

    International Nuclear Information System (INIS)

    Elmegreen, B.G.; Elmegreen, D.M.

    1983-01-01

    Spiral arm classifications were made for 261 low-inclination galaxies in groups listed by Huchra and Geller. The fractional occurrence of grand design spiral structure in nonbarred galaxies was found to increase from approx.0.1 to approx.0.6 and then level off as the group crossing rate or galaxy collision rate in a group increases. A simple model is discussed where the random encounters between galaxies of any type and flocculent galaxies induce transient grand design spirals in the flocculent galaxies. If this grand-design stimulation occurs for binary collisions with impact parameters less than αR 25 , were R 25 is the galactic radius at 25 mag arcsec - 2 , and if the induced grand design spirals persist for an average time equal to #betta# galactic rotations, then the quantity α 2 #betta# equals approximately 3 x 10 4 . If binary collisions are responsible for grand design spirals, then this result implies either that the induced spirals last for many galactic rotations (#betta#>15), or that they can be stimulated by very remote encounters (α>45.) Alternatively, grand design spirals may be stimulated by multiple galaxy encounters, which would be the case for such large α, or by interactions with the potential well of the associated group, rather than by simple binary encounters. Weak correlations between the grand design fraction and the galaxy size, or between this fraction and the total number of galaxies in a group, were also found. Spiral structures of barred galaxies show no correlations with group environment

  13. SPIRAL COUNTER-CURRENT CHROMATOGRAPHY OF SMALL MOLECULES, PEPTIDES AND PROTEINS USING THE SPIRAL TUBING SUPPORT ROTOR

    OpenAIRE

    Knight, Martha; Finn, Thomas M.; Zehmer, John; Clayton, Adam; Pilon, Aprile

    2011-01-01

    An important advance in countercurrent chromatography (CCC) carried out in open flow-tubing coils, rotated in planetary centrifuges, is the new design to spread out the tubing in spirals. More spacing between the tubing was found to significantly increase the stationary phase retention, such that now all types of two-phase solvent systems can be used for liquid-liquid partition chromatography in the J-type planetary centrifuges. A spiral tubing support (STS) frame with circular channels was c...

  14. Liquid Metal Droplet and Micro Corrugated Diaphragm RF-MEMS for reconfigurable RF filters

    Science.gov (United States)

    Irshad, Wasim

    detail and have proved pivotal to this work. The second part of the dissertation focuses on the Liquid Metal Droplet RF-MEMS. A novel tunable RF MEMS resonator that is based upon electrostatic control over the morphology of a liquid metal droplet (LMD) is conceived. We demonstrate an LMD evanescent-mode cavity resonator that simultaneously achieves wide analog tuning from 12 to 18 GHz with a measured quality factor of 1400-1840. A droplet of 250-mum diameter is utilized and the applied bias is limited to 100 V. This device operates on a principle called Electro-Wetting On Dielectric (EWOD). The liquid metal employed is a non-toxic eutectic alloy of Gallium, Indium and Tin known as Galinstan. This device also exploits interfacial surface energy and viscous body forces that dominate at nanoliter scale. We then apply our Liquid Metal Droplet (LMD) RF-MEMS architecture to demonstrate a continuously tunable electrostatic Ku-Band Filter. A 2-pole bandpass filter with measured insertion loss of less than 0.4dB and 3dB FBW of 3.4% is achieved using a Galinstan droplet of 250mum diameter and bias limited to 100V. We demonstrate that the LMD is insensitive to gravity by performing inversion and tilt experiments. In addition, we study its thermal tolerance by subjecting the LMD up to 150° C. The third part of the dissertation is dedicated to the Micro-Corrugated Diaphragm (MCD) RF-MEMS. We present an evanescent-mode cavity bandpass filter with state-of-the-art RF performance metrics like 4:1 tuning ratio from 5 to 20 GHz with less than 2dB insertion loss and 2-6% 3dB bandwidth. Micro-Corrugated Diaphragm (MCD) is a novel electrostatic MEMS design specifically engineered to provide large-scale analog deflections necessary for such continuous and wide tunable filtering with very high quality factor. We demonstrate a 1.25mm radius and 2mum thick Gold MCD which provides 30mum total deflection with nearly 60% analog range. We also present a detailed and systematic MCD design

  15. ESTABILIDADE DE CANAIS FLUVIAIS EM TORNO DE PONTES E BUEIROS NA BACIA HIDROGRÁFICA DO PARANÁ III, OESTE DO PARANÁ - EVALUATION OF THE CHANNEL STABILITY IN BRIDGES AND CULVERTS IN PARANÁ III WATERSHED, WESTERN PARANÁ STATE, BRAZIL

    Directory of Open Access Journals (Sweden)

    Leandro Neri Bortoluzzi

    2017-04-01

    The bridges and culverts alter the natural conditions of rivers, causing changes in fluvial processes. The level of stability of river banks and beds around crossing structures was evaluated in the Paraná III watershed, Western region of Paraná State (Brazil, adopting the methodology of FHWA (2006. A watershed has an area of 7,979.4 Km2 and it predominantly basaltic rocks of the Serra Geral Formation (Cretaceous that make up the basalt plateau with altitudes ranging between 220 and 725 m. The degree of channel stability was analyzed at 46 structures (18 bridges, 15 culverts box, 7 culverts pipe and 6 small bridges. We selected all crossings structures located in the Paraná III watershed along paved roads, positioned outside the urban area. Among the crossings structure, 13 were classified as excellent level of stability and 33 as good level. It was not registered any points with regular or poor stability. The prevalence of high levels of stability is credited to the outcrop of basalt substrate in bed and the low erodibility of the banks soils (Oxisols and Ultisols providing greater stability to the channel in the vicinity of the structures.

  16. Research on performance of upstream pumping mechanical seal with different deep spiral groove

    International Nuclear Information System (INIS)

    Wang, Q; Chen, H L; Liu, T; Liu, Y H; Liu, Z B; Liu, D H

    2012-01-01

    As one new type of mechanical seal, Upstream Pumping Mechanical Seal has been widely used in fluid machinery. In this paper, structure of spiral groove is innovatively optimized to improve performance of Upstream Pumping Mechanical Seal with Spiral Groove: keeping the dam zone and the weir zone not changed, changing the bottom shape of spiral groove only, substituting different deep spiral groove for equal deep spiral groove. The simulation on Upstream Pumping Mechanical Seal with different deep spiral grooves is done using FVM method. According to calculation, the performances of opening force and pressure distribution on seals face are obtained. Five types of spiral grooves are analyzed, namely equal deep spiral groove, circumferential convergent ladder-like different deep spiral groove, circumferential divergent ladder-like different deep spiral groove, radial convergent ladder-like different deep spiral groove and radial divergent ladder-like different deep spiral groove. This paper works on twenty-five working conditions. The results indicate the performances of circumferential divergent 2-ladder different deep spiral groove are better than the others, with more opening force and better stabilization, while with the same leakage. The outcome provides theoretical support for application of Upstream Pumping Mechanical Seal with circumferential convergent ladder-like different deep spiral groove.

  17. Research on performance of upstream pumping mechanical seal with different deep spiral groove

    Science.gov (United States)

    Wang, Q.; Chen, H. L.; Liu, T.; Liu, Y. H.; Liu, Z. B.; Liu, D. H.

    2012-11-01

    As one new type of mechanical seal, Upstream Pumping Mechanical Seal has been widely used in fluid machinery. In this paper, structure of spiral groove is innovatively optimized to improve performance of Upstream Pumping Mechanical Seal with Spiral Groove: keeping the dam zone and the weir zone not changed, changing the bottom shape of spiral groove only, substituting different deep spiral groove for equal deep spiral groove. The simulation on Upstream Pumping Mechanical Seal with different deep spiral grooves is done using FVM method. According to calculation, the performances of opening force and pressure distribution on seals face are obtained. Five types of spiral grooves are analyzed, namely equal deep spiral groove, circumferential convergent ladder-like different deep spiral groove, circumferential divergent ladder-like different deep spiral groove, radial convergent ladder-like different deep spiral groove and radial divergent ladder-like different deep spiral groove. This paper works on twenty-five working conditions. The results indicate the performances of circumferential divergent 2-ladder different deep spiral groove are better than the others, with more opening force and better stabilization, while with the same leakage. The outcome provides theoretical support for application of Upstream Pumping Mechanical Seal with circumferential convergent ladder-like different deep spiral groove.

  18. Multiple spiral patterns in the transitional disk of HD 100546

    Science.gov (United States)

    Boccaletti, A.; Pantin, E.; Lagrange, A.-M.; Augereau, J.-C.; Meheut, H.; Quanz, S. P.

    2013-12-01

    Context. Protoplanetary disks around young stars harbor many structures related to planetary formation. Of particular interest, spiral patterns were discovered among several of these disks and are expected to be the sign of gravitational instabilities leading to giant planet formation or gravitational perturbations caused by already existing planets. In this context, the star HD 100546 presents some specific characteristics with a complex gaseous and dusty disk that includes spirals, as well as a possible planet in formation. Aims: The objective of this study is to analyze high-contrast and high angular resolution images of this emblematic system to shed light on critical steps in planet formation. Methods: We retrieved archival images obtained at Gemini in the near IR (Ks band) with the instrument NICI and processed the data using an advanced high contrast imaging technique that takes advantage of the angular differential imaging. Results: These new images reveal the spiral pattern previously identified with Hubble Space Telescope (HST) with an unprecedented resolution, while the large-scale structure of the disk is mostly cancelled by the data processing. The single pattern to the southeast in HST images is now resolved into a multi-armed spiral pattern. Using two models of a gravitational perturber orbiting in a gaseous disk, we attempted to constrain the characteristics of this perturber, assuming that each spiral is independent, and drew qualitative conclusions. The non-detection of the northeast spiral pattern observed in HST allows putting a lower limit on the intensity ratio between the two sides of the disk, which if interpreted as forward scattering, yields a larger anisotropic scattering than is derived in the visible. Also, we find that the spirals are likely to be spatially resolved with a thickness of about 5-10 AU. Finally, we did not detect the candidate planet in formation recently discovered in the Lp band, with a mass upper limit of 16-18 MJ

  19. Single-shot spiral imaging at 7 T.

    Science.gov (United States)

    Engel, Maria; Kasper, Lars; Barmet, Christoph; Schmid, Thomas; Vionnet, Laetitia; Wilm, Bertram; Pruessmann, Klaas P

    2018-03-25

    The purpose of this work is to explore the feasibility and performance of single-shot spiral MRI at 7 T, using an expanded signal model for reconstruction. Gradient-echo brain imaging is performed on a 7 T system using high-resolution single-shot spiral readouts and half-shot spirals that perform dual-image acquisition after a single excitation. Image reconstruction is based on an expanded signal model including the encoding effects of coil sensitivity, static off-resonance, and magnetic field dynamics. The latter are recorded concurrently with image acquisition, using NMR field probes. The resulting image resolution is assessed by point spread function analysis. Single-shot spiral imaging is achieved at a nominal resolution of 0.8 mm, using spiral-out readouts of 53-ms duration. High depiction fidelity is achieved without conspicuous blurring or distortion. Effective resolutions are assessed as 0.8, 0.94, and 0.98 mm in CSF, gray matter and white matter, respectively. High image quality is also achieved with half-shot acquisition yielding image pairs at 1.5-mm resolution. Use of an expanded signal model enables single-shot spiral imaging at 7 T with unprecedented image quality. Single-shot and half-shot spiral readouts deploy the sensitivity benefit of high field for rapid high-resolution imaging, particularly for functional MRI and arterial spin labeling. © 2018 International Society for Magnetic Resonance in Medicine.

  20. Spiral waves characterization: Implications for an automated cardiodynamic tissue characterization.

    Science.gov (United States)

    Alagoz, Celal; Cohen, Andrew R; Frisch, Daniel R; Tunç, Birkan; Phatharodom, Saran; Guez, Allon

    2018-07-01

    Spiral waves are phenomena observed in cardiac tissue especially during fibrillatory activities. Spiral waves are revealed through in-vivo and in-vitro studies using high density mapping that requires special experimental setup. Also, in-silico spiral wave analysis and classification is performed using membrane potentials from entire tissue. In this study, we report a characterization approach that identifies spiral wave behaviors using intracardiac electrogram (EGM) readings obtained with commonly used multipolar diagnostic catheters that perform localized but high-resolution readings. Specifically, the algorithm is designed to distinguish between stationary, meandering, and break-up rotors. The clustering and classification algorithms are tested on simulated data produced using a phenomenological 2D model of cardiac propagation. For EGM measurements, unipolar-bipolar EGM readings from various locations on tissue using two catheter types are modeled. The distance measure between spiral behaviors are assessed using normalized compression distance (NCD), an information theoretical distance. NCD is a universal metric in the sense it is solely based on compressibility of dataset and not requiring feature extraction. We also introduce normalized FFT distance (NFFTD) where compressibility is replaced with a FFT parameter. Overall, outstanding clustering performance was achieved across varying EGM reading configurations. We found that effectiveness in distinguishing was superior in case of NCD than NFFTD. We demonstrated that distinct spiral activity identification on a behaviorally heterogeneous tissue is also possible. This report demonstrates a theoretical validation of clustering and classification approaches that provide an automated mapping from EGM signals to assessment of spiral wave behaviors and hence offers a potential mapping and analysis framework for cardiac tissue wavefront propagation patterns. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Negative spiral CT in acute pulmonary embolism

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, T.; Olausson, A. [Karolinska Hospital, Stockholm (Sweden). Dept. of Thoracic Radiology; Johnsson, H. [Karolinska Hospital, Stockholm (Sweden). Dept. of Internal Medicine; Nyman, U. [County Hospital, Trelleborg (Sweden). Dept. of Radiology; Aspelin, P. [Huddinge Univ. Hospital (Sweden). Dept. of Radiology

    2002-09-01

    Purpose: To retrospectively evaluate the clinical outcome of non-anticoagulated patients with clinically suspected acute pulmonary embolism (PE) and no symptoms or signs of deep venous thrombosis (DVT) following a negative contrast medium-enhanced spiral CT of the pulmonary arteries (s-CTPA). Material and Methods: During a 24-month period, 739 of 751 patients underwent s-CTPA with acceptable diagnostic quality for clinically suspected acute PE. All patients who had a CT study not positive for PE were followed up with a questionnaire, a telephone interview and review of all medical reports, including autopsies and death certificates for any episodes of venous thromboembolism (VTE) during a 3-month period. Results: PE was diagnosed in 158 patients. Of the remaining 581 patients with a negative s-CTPA, 45 patients were lost to follow-up. 88 patients were excluded because of anticoagulation treatment (cardiac disorder n=32, chronic VTE or acute symptomatic DVT n=31, PE diagnosed at pulmonary angiography n=1, thrombus prophylaxis during diagnostic work-up or other reasons than VTE n=24) and 7 patients undergoing lower extremity venous studies because of symptoms of DVT (all negative). Thus, 441 patients with a negative s-CTPA and no DVT symptoms, venous studies or anticoagulant treatment constituted the follow-up cohort. Four of these patients had proven VTE (all PE) during the 3-month follow-up period. Two of the PE episodes contributed to the patient's death. Conclusion: Patients with clinically suspected acute PE, no symptoms or signs of DVT and a negative single slice s-CTPA using 3-5 mm collimation, may safely be left without anticoagulation treatment unless they are critically ill, have a limited cardiopulmonary reserve and/or if a high clinical suspicion remains.

  2. CHARACTERIZING SPIRAL ARM AND INTERARM STAR FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Kreckel, K.; Schinnerer, E.; Meidt, S. [Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Blanc, G. A. [Departamento de Astronomía, Universidad de Chile, Camino del Observatorio 1515, Las Condes, Santiago (Chile); Groves, B. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Adamo, A. [Department of Astronomy, The Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Hughes, A., E-mail: kreckel@mpia.de [CNRS, IRAP, 9 Av. du Colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France)

    2016-08-20

    Interarm star formation contributes significantly to a galaxy’s star formation budget and provides an opportunity to study stellar birthplaces unperturbed by spiral arm dynamics. Using optical integral field spectroscopy of the nearby galaxy NGC 628 with VLT/MUSE, we construct H α maps including detailed corrections for dust extinction and stellar absorption to identify 391 H ii regions at 35 pc resolution over 12 kpc{sup 2}. Using tracers sensitive to the underlying gravitational potential, we associate H ii regions with either arm (271) or interarm (120) environments. Using our full spectral coverage of each region, we find that most physical properties (luminosity, size, metallicity, ionization parameter) of H ii regions are independent of environment. We calculate the fraction of H α luminosity due to the background of diffuse ionized gas (DIG) contaminating each H ii region, and find the DIG surface brightness to be higher within H ii regions than in the surroundings, and slightly higher within arm H ii regions. Use of the temperature-sensitive [S ii]/H α line ratio instead of the H α surface brightness to identify the boundaries of H ii regions does not change this result. Using the dust attenuation as a tracer of the gas, we find depletion times consistent with previous work (2 × 10{sup 9} yr) with no differences between the arm and interarm, but this is very sensitive to the DIG correction. Unlike molecular clouds, which can be dynamically affected by the galactic environment, we see fairly consistent properties of H ii regions in both arm and interarm environments. This suggests either a difference in star formation and feedback in arms or a decoupling of dense star-forming clumps from the more extended surrounding molecular gas.

  3. Formation of polymeric toroidal-spiral particles.

    Science.gov (United States)

    Sharma, Vishal; Szymusiak, Magdalena; Shen, Hao; Nitsche, Ludwig C; Liu, Ying

    2012-01-10

    Compared to spherical matrices, particles with well-defined internal structure provide large surface to volume ratio and predictable release kinetics for the encapsulated payloads. We describe self-assembly of polymeric particles, whereby competitive kinetics of viscous sedimentation, diffusion, and cross-linking yield a controllable toroidal-spiral (T-S) structure. Precursor polymeric droplets are splashed through the surface of a less dense, miscible solution, after which viscous forces entrain the surrounding bulk solution into the sedimenting polymer drop to form T-S channels. The intricate structure forms because low interfacial tension between the two miscible solutions is dominated by viscous forces. The biocompatible polymer, poly(ethylene glycol) diacrylate (PEG-DA), is used to demonstrate the solidification of the T-S shapes at various configurational stages by UV-triggered cross-linking. The dimensions of the channels are controlled by Weber number during impact on the surface, and Reynolds number and viscosity ratio during subsequent sedimentation. We anticipate applications of the T-S particle in drug delivery, wherein diffusion through these T-S channels and the polymer matrix would offer parallel release pathways for molecules of different sizes. Polyphosphate, as a model macromolecule, is entrained in T-S particles during their formation. The in vitro release kinetics of polyphosphate from the T-S particles with various channel length and width is reported. In addition, self-assembly of T-S particles occurs in a single step under benign conditions for delicate macromolecules, and appears conducive to scaleup.

  4. Development of ideal solution and validation of stiffness and strength by finite element method for truss-wall corrugated cellular solids

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeong Ho [Samjung E and W, Changwon (Korea, Republic of); Lee, Jung Hwan [Korea Institute of Materials Science,Changwon (Korea, Republic of); Lee, Je Hyun [Changwon National University, Changwon (Korea, Republic of)

    2014-05-15

    The objective of this study is to find the density, stiffness, and strength of truss-wall unit cell models. The diamond-corrugation, triangular-corrugation, and Navtruss-corrugation models are used for the unit cell. The ideal solutions derived for these are based on solid wall unit cell models and are developed using the Gibson-Ashby theory. To verify the ideal solutions of the models, the density, strength, and stiffness are simulated using ABAQUS software and compared with the ideal solutions on a log-log scale. The material properties of stainless steel 304 are applied. The diameter is 0.5 mm; the opening width is 0.5 mm; and the corrugation angle is 45 .deg. . Consequently, the relative Young's modulus and relative yield strength of the truss-wall unit models are good matches for the ideal expectations. It may be possible to apply a truss-wall model to diverse fields such as transportation or biomedical applications as one of the open-cell cellular solids.

  5. Monotron and azimuthally corrugated: application to the high power microwaves generation; Monotron e cavidades azimutalmente corrugadas: aplicacao a geracao de microondas de alta potencia

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Pedro Jose de

    2003-07-01

    The present document reports the activity of construction and initial operation of 6.7 GHz operation for high power microwave generation, the study on cylindrical resonators with azimuthally corrugated cross section, the determination of electrical conductivity of metallic materials and development of dielectric resonators for telecommunication applications.

  6. Development of ideal solution and validation of stiffness and strength by finite element method for truss-wall corrugated cellular solids

    International Nuclear Information System (INIS)

    Choi, Jeong Ho; Lee, Jung Hwan; Lee, Je Hyun

    2014-01-01

    The objective of this study is to find the density, stiffness, and strength of truss-wall unit cell models. The diamond-corrugation, triangular-corrugation, and Navtruss-corrugation models are used for the unit cell. The ideal solutions derived for these are based on solid wall unit cell models and are developed using the Gibson-Ashby theory. To verify the ideal solutions of the models, the density, strength, and stiffness are simulated using ABAQUS software and compared with the ideal solutions on a log-log scale. The material properties of stainless steel 304 are applied. The diameter is 0.5 mm; the opening width is 0.5 mm; and the corrugation angle is 45 .deg. . Consequently, the relative Young's modulus and relative yield strength of the truss-wall unit models are good matches for the ideal expectations. It may be possible to apply a truss-wall model to diverse fields such as transportation or biomedical applications as one of the open-cell cellular solids.

  7. New insights into the short pitch corrugation development enigma based on 3D-FE dynamic vehicle-track coupled modelling in frictional rolling contact

    NARCIS (Netherlands)

    Li, S.; Li, Z.; Nunez Vicencio, Alfredo; Dollevoet, R.P.B.J.

    2017-01-01

    A three-dimensional (3D) finite element (FE) dynamic frictional rolling contact model is presented for the study of short pitch corrugation that considers direct and instantaneous coupling between the contact mechanics and the structural dynamics in a vehicle-track system. In this study, we examine

  8. Stabilization of spiral wave and turbulence in the excitable media using parameter perturbation scheme

    International Nuclear Information System (INIS)

    Ma Jun; Wang Chunni; Li Yanlong; Pu Zhongsheng; Jin Wuyin

    2008-01-01

    This paper proposes a scheme of parameter perturbation to suppress the stable rotating spiral wave, meandering spiral wave and turbulence in the excitable media, which is described by the modified Fitzhugh–Nagumo (MFHN) model. The controllable parameter in the MFHN model is perturbed with a weak pulse and the pulse period is decided by the rotating period of the spiral wave approximatively. It is confirmed that the spiral wave and spiral turbulence can be suppressed greatly. Drift and instability of spiral wave can be observed in the numerical simulation tests before the whole media become homogeneous finally. (general)

  9. Can cluster environment modify the dynamical evolution of spiral galaxies?

    Science.gov (United States)

    Amram, P.; Balkowski, C.; Cayatte, V.; Marcelin, M.; Sullivan, W. T., III

    1993-01-01

    Over the past decade many effects of the cluster environment on member galaxies have been established. These effects are manifest in the amount and distribution of gas in cluster spirals, the luminosity and light distributions within galaxies, and the segregation of morphological types. All these effects could indicate a specific dynamical evolution for galaxies in clusters. Nevertheless, a more direct evidence, such as a different mass distribution for spiral galaxies in clusters and in the field, is not yet clearly established. Indeed, Rubin, Whitmore, and Ford (1988) and Whitmore, Forbes, and Rubin (1988) (referred to as RWF) presented evidence that inner cluster spirals have falling rotation curves, unlike those of outer cluster spirals or the great majority of field spirals. If falling rotation curves exist in centers of clusters, as argued by RWF, it would suggest that dark matter halos were absent from cluster spirals, either because the halos had become stripped by interactions with other galaxies or with an intracluster medium, or because the halos had never formed in the first place. Even if they didn't disagree with RWF, other researchers pointed out that the behaviour of the slope of the rotation curves of spiral galaxies (in Virgo) is not so clear. Amram, using a different sample of spiral galaxies in clusters, found only 10% of declining rotation curves (2 declining vs 17 flat or rising) in opposition to RWF who find about 40% of declining rotation curves in their sample (6 declining vs 10 flat or rising), we will hereafter briefly discuss the Amram data paper and compare it to the results of RWF. We have measured the rotation curves for a sample of 21 spiral galaxies in 5 nearby clusters. These rotation curves have been constructed from detailed two-dimensional maps of each galaxy's velocity field as traced by emission from the Ha line. This complete mapping, combined with the sensitivity of our CFHT 3.60 m. + Perot-Fabry + CCD observations, allows

  10. On wave dark matter in spiral and barred galaxies

    International Nuclear Information System (INIS)

    Martinez-Medina, Luis A.; Matos, Tonatiuh; Bray, Hubert L.

    2015-01-01

    We recover spiral and barred spiral patterns in disk galaxy simulations with a Wave Dark Matter (WDM) background (also known as Scalar Field Dark Matter (SFDM), Ultra-Light Axion (ULA) dark matter, and Bose-Einstein Condensate (BEC) dark matter). Here we show how the interaction between a baryonic disk and its Dark Matter Halo triggers the formation of spiral structures when the halo is allowed to have a triaxial shape and angular momentum. This is a more realistic picture within the WDM model since a non-spherical rotating halo seems to be more natural. By performing hydrodynamic simulations, along with earlier test particles simulations, we demonstrate another important way in which wave dark matter is consistent with observations. The common existence of bars in these simulations is particularly noteworthy. This may have consequences when trying to obtain information about the dark matter distribution in a galaxy, the mere presence of spiral arms or a bar usually indicates that baryonic matter dominates the central region and therefore observations, like rotation curves, may not tell us what the DM distribution is at the halo center. But here we show that spiral arms and bars can develop in DM dominated galaxies with a central density core without supposing its origin on mechanisms intrinsic to the baryonic matter

  11. Spiral CT findings of inflammatory pseudotumor of the liver

    International Nuclear Information System (INIS)

    Lee, Ha Jong; Nam, Kyung Jin; Lee, Ki Nam; Park, Byeong Ho; Choi, Jong Cheol; Koo, Bong Sik; Nam, Ki Dong; Kim, Chan Seong

    1998-01-01

    To assess the spiral CT findings of inflammatory pseudotumor of the liver(IPTL), in order to distinguish this tumor from hepatocellular carcinoma, hepatic abscess or other space occupying liver lesions. The spiral CT findings of IPTL were retrospectively evaluated in six patients. All cases were confirmed by ultrasonography-guided gun biopsy. Four patients were men and two were women, and they were aged between 37 and 74 (mean, 49) years. The site, size, and number of IPTL were assessed, and their enhancement patterns were evaluated during the arterial, portal and delayed phases of spiral CT. Five cases involved a solitary mass and in one there were multiple masses with surrounding small nodules. Four cases occurred in the right lobe and two in the left lobe. Four of five surrounding nodules were in the left lobe. During the arterial phase of spiral CT scanning, three layers were separated from four of five cases of solitary mass;they were composed of central and peripheral portions of low attenuation, and an intermediate portion of isoattenuation. Delayed enhancement of the peripheral portion was prominent during the delayed phase. In the case involving multiple masses three layers were not seen during the arterial phase, but during the delayed phase enhancement was noted. The features of three layers, as seen on spiral CT, is considered to be very specific for distinguishing IPTL from other hepatic focal lesions.=20

  12. A spiral-based volumetric acquisition for MR temperature imaging.

    Science.gov (United States)

    Fielden, Samuel W; Feng, Xue; Zhao, Li; Miller, G Wilson; Geeslin, Matthew; Dallapiazza, Robert F; Elias, W Jeffrey; Wintermark, Max; Butts Pauly, Kim; Meyer, Craig H

    2018-06-01

    To develop a rapid pulse sequence for volumetric MR thermometry. Simulations were carried out to assess temperature deviation, focal spot distortion/blurring, and focal spot shift across a range of readout durations and maximum temperatures for Cartesian, spiral-out, and retraced spiral-in/out (RIO) trajectories. The RIO trajectory was applied for stack-of-spirals 3D imaging on a real-time imaging platform and preliminary evaluation was carried out compared to a standard 2D sequence in vivo using a swine brain model, comparing maximum and mean temperatures measured between the two methods, as well as the temporal standard deviation measured by the two methods. In simulations, low-bandwidth Cartesian trajectories showed substantial shift of the focal spot, whereas both spiral trajectories showed no shift while maintaining focal spot geometry. In vivo, the 3D sequence achieved real-time 4D monitoring of thermometry, with an update time of 2.9-3.3 s. Spiral imaging, and RIO imaging in particular, is an effective way to speed up volumetric MR thermometry. Magn Reson Med 79:3122-3127, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  13. Propagating star formation and irregular structure in spiral galaxies

    International Nuclear Information System (INIS)

    Mueller, M.W.; Arnett, W.D.

    1976-01-01

    A simple model is proposed which describes the irregular optical appearance often seen in late-type spiral galaxies. If high-mass stars produce spherical shock waves which induce star formation, new high-mass stars will be born which, in turn, produce new shock waves. When this process operates in a differentially rotating disk, our numerical model shows that large-scale spiral-shaped regions of star formation are built up. The structure is seen to be most sensitive to a parameter which governs how often a region of the interstellar medium can undergo star formation. For a proper choice of this parameter, large-scale features disappear before differential rotation winds them up. New spiral features continuously form, so some spiral structure is seen indefinitely. The structure is not the classical two-armed symmetric spiral pattern which the density-wave theory attempts to explain, but it is asymmetric and disorderly.The mechanism of propagating star formation used in our model is consistent with observations which connect young OB associations with expanding shells of gas. We discuss the possible interaction of this mechanism with density waves

  14. Spiral scan long object reconstruction through PI line reconstruction

    International Nuclear Information System (INIS)

    Tam, K C; Hu, J; Sourbelle, K

    2004-01-01

    The response of a point object in a cone beam (CB) spiral scan is analysed. Based on the result, a reconstruction algorithm for long object imaging in spiral scan cone beam CT is developed. A region-of-interest (ROI) of the long object is scanned with a detector smaller than the ROI, and a portion of it can be reconstructed without contamination from overlaying materials. The top and bottom surfaces of the ROI are defined by two sets of PI lines near the two ends of the spiral path. With this novel definition of the top and bottom ROI surfaces and through the use of projective geometry, it is straightforward to partition the cone beam image into regions corresponding to projections of the ROI, the overlaying objects or both. This also simplifies computation at source positions near the spiral ends, and makes it possible to reduce radiation exposure near the spiral ends substantially through simple hardware collimation. Simulation results to validate the algorithm are presented

  15. Continuing research on the classical spiraling photon model

    Science.gov (United States)

    Li, Hongrui

    2014-11-01

    Based no the classical spiraling photon model proposed by Hongrui Li, the laws of reflection, refraction of a single photon can be derived. Moreover, the polarization, total reflection, evanescent wave and Goos-Hanchen shift of a single photon can be elucidated. However, this photon model is still unfinished. Especially, the spiraling diameter of a photon is not definite. In this paper, the continuous research works on this new theory are reported. According to the facts that the diffraction limit of light and the smallest diameter of the focal spot of lenses are all equal to the wavelength λ of the light, we can get that the spiraling diameter of a photon equals to the wavelength λ, so we gain that the angle between the linear velocity of the spiraling photon υ and the component of the linear velocity in the forward direction υb is 45°, and the energy of a classical spiraling photon E = (1/2)mυ2 = (1/2)m2c2 = mc2. This coincides with Einstein's mass-energy relation. While it is obtained that the velocity of the evanescent wave in the vacuum is slower than the velocity of light in glass in straight line. In such a way, the optical fiber can slow the light down. In addition, the force analysis of a single photon in optical tweezers system is discussed. And the reason that the laser beam can capture the particle slightly downstream from the focal point can be explained.

  16. Three dimensional corrugated organic photovoltaics for building integration; improving the efficiency, oblique angle and diffuse performance of solar cells

    DEFF Research Database (Denmark)

    Kettle, Jeff; Bristow, Noel; Sweet, Tracy K. N.

    2015-01-01

    The lamination of OPV modules to corrugated roof cladding has been undertaken. The 3-dimensional form of the cladding provides three advantages for outdoor OPV deployment; firstly the ‘footprint’ of the solar cell is reduced, which leads to B10% improved power conversion (PCE) efficiency per unit...... area. Secondly, the oblique angle performance is enhanced, leading to increased output in the early morning and evening. Indoor characterisation showed a 9-fold enhancement in efficiency was obtainable, when compared to a flat module. Thirdly, an improvement in performance under diffuse lighting...... conditions was measured, when compared to a flat module. The average daily yield of the 3D module was 17–29% higher than a flat module, with higher relative enhancements observed on cloudier days. Geographically, the 3D module appears to be well-suited to countries with a high latitude, due to the enhanced...

  17. Alkali reduction of graphene oxide in molten halide salts: production of corrugated graphene derivatives for high-performance supercapacitors.

    Science.gov (United States)

    Abdelkader, Amr M; Vallés, Cristina; Cooper, Adam J; Kinloch, Ian A; Dryfe, Robert A W

    2014-11-25

    Herein we present a green and facile approach to the successful reduction of graphene oxide (GO) materials using molten halide flux at 370 °C. GO materials have been synthesized using a modified Hummers method and subsequently reduced for periods of up to 8 h. Reduced GO (rGO) flakes have been characterized using X-ray-diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR), all indicating a significantly reduced amount of oxygen-containing functionalities on the rGO materials. Furthermore, impressive electrical conductivities and electrochemical capacitances have been measured for the rGO flakes, which, along with the morphology determined from scanning electron microscopy, highlight the role of surface corrugation in these rGO materials.

  18. Methods to introduce sub-micrometer, symmetry-breaking surface corrugation to silicon substrates to increase light trapping

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sang Eon; Hoard, Brittany R.; Han, Sang M.; Ghosh, Swapnadip

    2018-04-10

    Provided is a method for fabricating a nanopatterned surface. The method includes forming a mask on a substrate, patterning the substrate to include a plurality of symmetry-breaking surface corrugations, and removing the mask. The mask includes a pattern defined by mask material portions that cover first surface portions of the substrate and a plurality of mask space portions that expose second surface portions of the substrate, wherein the plurality of mask space portions are arranged in a lattice arrangement having a row and column, and the row is not oriented parallel to a [110] direction of the substrate. The patterning the substrate includes anisotropically removing portions of the substrate exposed by the plurality of spaces.

  19. Broadband Amplification of Low-Terahertz Signals Using Axis-Encircling Electrons in a Helically Corrugated Interaction Region

    Science.gov (United States)

    He, W.; Donaldson, C. R.; Zhang, L.; Ronald, K.; Phelps, A. D. R.; Cross, A. W.

    2017-11-01

    Experimental results are presented of a broadband, high power, gyrotron traveling wave amplifier (gyro-TWA) operating in the (75-110)-GHz frequency band and based on a helically corrugated interaction region. The second harmonic cyclotron mode of a 55-keV, 1.5-A, axis-encircling electron beam is used to resonantly interact with a traveling TE21 -like eigenwave achieving broadband amplification. The gyro-TWA demonstrates a 3-dB gain bandwidth of at least 5.5 GHz in the experimental measurement with 9 GHz predicted for a wideband drive source with a measured unsaturated output power of 3.4 kW and gain of 36-38 dB. The approach may allow a gyro-TWA to operate at 1 THz.

  20. A Comparative Study of Dispersion Characteristics Determination of a Trapezoidally Corrugated Slow Wave Structure Using Different Techniques

    International Nuclear Information System (INIS)

    Saber, Md. Ghulam; Sagor, Rakibul Hasan; Amin, Md. Ruhul

    2016-01-01

    The linear dispersion relation of a trapezoidally corrugated slow wave structure (TCSWS) is analyzed and presented. The size parameters of the TCSWS are chosen in such a way that they operate in the x-band frequency range. The dispersion relation is solved by utilizing the Rayleigh–Fourier method by expressing the radial function in terms of the Fourier series. A highly accurate synthetic technique is also applied to determine the complete dispersion characteristics from experimentally measured resonances (cold test). Periodic structures resonate at specific frequencies when the terminals are shorted appropriately. The dispersion characteristics obtained from numerical calculation, synthetic technique and cold test are compared, and an excellent agreement is achieved. (paper)

  1. Geometrical study of phyllotactic patterns by Bernoulli spiral lattices.

    Science.gov (United States)

    Sushida, Takamichi; Yamagishi, Yoshikazu

    2017-06-01

    Geometrical studies of phyllotactic patterns deal with the centric or cylindrical models produced by ideal lattices. van Iterson (Mathematische und mikroskopisch - anatomische Studien über Blattstellungen nebst Betrachtungen über den Schalenbau der Miliolinen, Verlag von Gustav Fischer, Jena, 1907) suggested a centric model representing ideal phyllotactic patterns as disk packings of Bernoulli spiral lattices and presented a phase diagram now called Van Iterson's diagram explaining the bifurcation processes of their combinatorial structures. Geometrical properties on disk packings were shown by Rothen & Koch (J. Phys France, 50(13), 1603-1621, 1989). In contrast, as another centric model, we organized a mathematical framework of Voronoi tilings of Bernoulli spiral lattices and showed mathematically that the phase diagram of a Voronoi tiling is graph-theoretically dual to Van Iterson's diagram. This paper gives a review of two centric models for disk packings and Voronoi tilings of Bernoulli spiral lattices. © 2017 Japanese Society of Developmental Biologists.

  2. Extending the GANIL control system for the SPIRAL project

    International Nuclear Information System (INIS)

    Lecorche, E.

    1997-01-01

    The SPIRAL project under construction at GANIL aims to deliver radioactive ion beams to the physicists by the end of 1998. In 1996, it has been proposed to achieve most of the SPIRAL control system as an extension of the system currently in use at GANIL. Therefore the main features of the GANIL control system design are first recalled. Then the paper shows how the GANIL control system should have been upgraded and extended to integrate the SPIRAL project. This evolution had to cope with the specific needs brought by the new machine and to consider the size of the project which is around one third of the GANIL control system volume. Lastly current status of the system is given. (author)

  3. Kinematical and dynamical models for barred spiral galaxies

    International Nuclear Information System (INIS)

    Davoust, E.

    1983-01-01

    This is a review of published works on the kinematics and dynamics of stellar bars and barred spiral galaxies. The periodic orbits of stars are elongated along the bar and enhance it out to a certain distance from the center. The important role of the interstellar gas is pointed out by the models of gas clouds and flows: the trajectories are also along the bar, but shock waves arise in front of the bar and transient spiral structures appear at its ends. These models reproduce the observed velocity fields fairly well. The investigations of the stability of axisymmetric galactic disks show that they are very unstable with respect to bar shaped perturbations and might explain why two thirds of the known spiral galaxies are barred [fr

  4. Vascular imaging with spiral CT. The way to CY angiography

    International Nuclear Information System (INIS)

    Prokop, M.; Schaefer, C.; Kalender, W.A.; Polacin, A.; Galanski, M.

    1993-01-01

    Spiral CT is a technique that allows for high-quality two-dimensional angiographic projections and 3D imaging of vascular structures. The authors present the technical and methodological principles of the technique, including scan parameters and parameters of contrast application for various clinical imaging tasks. They present their experience with over 150 clinical cases using spiral CT angiography. Suitable applications of this technique include cogenital anomalies, aneurysms, dissections, stenoses, thrombi and vascular tumor involvement. Given a problem-adapted examination technique, pathologic changes in vessels of as little as 2 mm can be visualized. In some cases with complex vascular anatomy, spiral CT angiography can be superior to arterial angiography. (orig.) [de

  5. Extending the GANIL control system for the SPIRAL project

    Energy Technology Data Exchange (ETDEWEB)

    Lecorche, E

    1997-12-31

    The SPIRAL project under construction at GANIL aims to deliver radioactive ion beams to the physicists by the end of 1998. In 1996, it has been proposed to achieve most of the SPIRAL control system as an extension of the system currently in use at GANIL. Therefore the main features of the GANIL control system design are first recalled. Then the paper shows how the GANIL control system should have been upgraded and extended to integrate the SPIRAL project. This evolution had to cope with the specific needs brought by the new machine and to consider the size of the project which is around one third of the GANIL control system volume. Lastly current status of the system is given. (author) 5 refs.

  6. Auditory Mechanics of the Tectorial Membrane and the Cochlear Spiral

    Science.gov (United States)

    Gavara, Núria; Manoussaki, Daphne; Chadwick, Richard S.

    2012-01-01

    Purpose of review This review is timely and relevant since new experimental and theoretical findings suggest that cochlear mechanics from the nanoscale to the macroscale are affected by mechanical properties of the tectorial membrane and the spiral shape. Recent findings Main tectorial membrane themes covered are i) composition and morphology, ii) nanoscale mechanical interactions with the outer hair cell bundle, iii) macroscale longitudinal coupling, iv) fluid interaction with inner hair cell bundles, v) macroscale dynamics and waves. Main cochlear spiral themes are macroscale low-frequency energy focusing and microscale organ of Corti shear gain. Implications Findings from new experimental and theoretical models reveal exquisite sensitivity of cochlear mechanical performance to tectorial membrane structural organization, mechanics, and its positioning with respect to hair bundles. The cochlear spiral geometry is a major determinant of low frequency hearing. Suggestions are made for future research directions. PMID:21785353

  7. Visibility in a pure model of golden spiral phyllotaxis.

    Science.gov (United States)

    Herrmann, Burghard

    2018-07-01

    This paper considers the geometry of plants with golden spiral phyllotaxis, i.e. growing leaf by leaf on a spiral with golden divergence angle, via the simplest mathematical model, a cylinder with regular arrangement of points on its surface. As is well-known, Fibonacci numbers appear by means of the order of parastichies. This fact is shown to be a straightforward application of logical consequences to a particular model with respect to pure visibility. This notion is very similar to that of contact parastichies. The 3-D cylindrical model of golden spiral phyllotaxis abstracts from the form of leaves and identifies them with points. Pure visibility is specified in the 2-D representation so that common sense parastichies can be scrutinized. The main Theorem states that the orders of the purely most visible parastichies are Fibonacci numbers. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Shunt impedance of spiral loaded resonant rf cavities

    International Nuclear Information System (INIS)

    Peebles, P.Z. Jr.; Parvarandeh, M.

    1975-01-01

    Based upon a treatment of the spiral loaded resonant radio frequency cavity as a shorted quarter-wave transmission line, a model for shunt impedance is developed. The model is applicable to loosely wound spirals in large diameter containers. Theoretical shunt impedance is given for spirals wound from tubing of circular or rectangular cross section. The former produces higher shunt impedance. Measurements made at Oak Ridge National Laboratory on 17 copper cavities are described which support the theoretical results. Theoretical results are also compared to data from twenty-three additional cavities measured at Los Alamos Scientific Laboratory. It is shown that the theoretical function forms a useful means of interpreting the quality of constructed cavities. (author)

  9. Global spiral structure of M81 - radio continuum maps

    International Nuclear Information System (INIS)

    Bash, F.N.; Kaufman, M.; Ohio State Univ., Columbus)

    1986-01-01

    VLA observations of the radio continuum emission from M81 at 6 and 20 cm are presented and used to check the predictions of density-wave theories. Both thermal and nonthermal radiation from the spiral arms are detected. Most of the bright knots along the radio arms are giant radio H II regions. The nonthermal emission defines spiral arms that are patchy and well-resolved, with a width of 1-2 kpc. The observed nonthermal arms are too broad to agree with the continuum gasdynamical calculations of Roberts (1969), Shu et al. (1972), and Visser (1978, 1980) for a classical density wave model. The observed arm widths appear consistent with the predictions of density-wave models that emphasize the clumpy nature of the ISM. The 20 cm arms appear to spiral outward from a faint inner H I ring, suggesting that the ring is produced by the inner Lindblad resonance. 36 references

  10. Simulation algorithm for spiral case structure in hydropower station

    Directory of Open Access Journals (Sweden)

    Xin-yong Xu

    2013-04-01

    Full Text Available In this study, the damage-plasticity model for concrete that was verified by the model experiment was used to calculate the damage to a spiral case structure based on the damage mechanics theory. The concrete structure surrounding the spiral case was simulated with a three-dimensional finite element model. Then, the distribution and evolution of the structural damage were studied. Based on investigation of the change of gap openings between the steel liner and concrete structure, the impact of the non-uniform variation of gaps on the load-bearing ratio between the steel liner and concrete structure was analyzed. The comparison of calculated results of the simplified and simulation algorithms shows that the simulation algorithm is a feasible option for the calculation of spiral case structures. In addition, the shell-spring model was introduced for optimization analysis, and the results were reasonable.

  11. The scientific objectives of the SPIRAL 2 Project

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, D.; Adoui, L.; Angelis, G. de [GANIL, Grand Accelerateur National d' Ions Lourds, BP 55027, 14076 Caen cedex 5 (France)] (and others)

    2006-06-15

    The construction of SPIRAL 2 at GANIL will open completely new possibilities for parallel beam operation of the whole facility. The whole GANIL/SPIRAL/SPIRAL2 accelerator complex will allow for the simultaneous use of up to 5 different radioactive and stable beams. Several combinations of different beams delivered in parallel for experiments at low (keV/u), medium (few MeV/u) and high (up to 100 MeV/u) energies will be possible. Presently the GANIL/SPIRAL facility delivers about 60 weeks per year of stable and radioactive beams (up to 3 simultaneous beams). Thanks to SPIRAL 2 and the construction of a new beam line connecting the CIME cyclotron and the G1 and G2 experimental rooms the available beam time for experiments may be extended up to about 120 (up to 5 simultaneous beams) weeks per year. The chapters which follow a general introduction deal with the detailed questions to be addressed by experiments with the beams from SPIRAL2. In chapter 2 the many unanswered questions related to the structure of exotic nuclei are posed and the role of SPIRAL2 in answering them outlined. Chapter 3 deals with the dynamics and thermodynamics of asymmetric nuclear systems. Chapter 4 is concerned with questions of nuclear astrophysics which are intimately related to the properties of exotic nuclei. Chapter 5 indicates how the atomic nucleus can act as a laboratory for tests of the Standard model of Particle Physics and Chapter 6 shows how the production of intense fluxes of neutrons at SPIRAL2 make it an excellent tool to address both questions related to damage in materials of importance in nuclear installations and to the s- and r-processes of nucleosynthesis. In chapter 7 we turn to the application, of the radioactive beams from SPIRAL2 and the radionuclides produced by it, to study condensed matter and radiobiology. Finally in the eight and last chapter the reader can find an account of the historical development of the SPIRAL2 facility and this is followed by an outline of

  12. Flocculent and grand design spiral arm structure in cluster galaxies

    International Nuclear Information System (INIS)

    Elmegreen, D.M.

    1982-01-01

    A total of 829 spiral galaxies in 22 clusters having redshifts between z = 0.02 and 0.06 were classified according to the appearance of their spiral arm structures. The fraction of galaxies that have a grand design spiral structure was found to be higher among barred galaxies than among non-barred galaxies (at z = 0.02, 95 per cent of strongly barred galaxies have a grand design, compared with 67 per cent of non-barred or weakly barred galaxies). Cluster galaxies and distant non-cluster galaxies have the same fraction of grand design galaxies when resolution effects are considered. The grand design fraction among cluster galaxies is also similar to the fraction observed among nearby galaxies in binary systems and in groups. (author)

  13. New developments in the theory of spiral galaxies

    International Nuclear Information System (INIS)

    Thielheim, K.O.

    1982-01-01

    About 30% of all galaxies exhibit spiral forms, 60% are elliptical and 10% irregular. It is the objective of galactic dynamics to explain these structural features. A first generation of self-consistent N-body simulations indicates that ellipticals are equilibrium configurations of gravitationally interacting multi-particle systems for which unfortunately a theory does not yet exist. Recent progress has been made on the modal analysis of Freeman disks. In a second generation of N-body simulations spiral density waves have been reproduced in disk configurations. As an alternative to the Lin-Shu conjecture based on the QSSS-hypothesis the author considers a mechanism by which spiral density waves are produced in the surrounding disk as a consequence of the slow increase of the quadrupole moment of a central oval shaped equilibrium configuration immersed in the disk. (Auth.)

  14. The scientific objectives of the SPIRAL 2 Project

    International Nuclear Information System (INIS)

    Ackermann, D.; Adoui, L.; Angelis, G. de

    2006-06-01

    The construction of SPIRAL 2 at GANIL will open completely new possibilities for parallel beam operation of the whole facility. The whole GANIL/SPIRAL/SPIRAL2 accelerator complex will allow for the simultaneous use of up to 5 different radioactive and stable beams. Several combinations of different beams delivered in parallel for experiments at low (keV/u), medium (few MeV/u) and high (up to 100 MeV/u) energies will be possible. Presently the GANIL/SPIRAL facility delivers about 60 weeks per year of stable and radioactive beams (up to 3 simultaneous beams). Thanks to SPIRAL 2 and the construction of a new beam line connecting the CIME cyclotron and the G1 and G2 experimental rooms the available beam time for experiments may be extended up to about 120 (up to 5 simultaneous beams) weeks per year. The chapters which follow a general introduction deal with the detailed questions to be addressed by experiments with the beams from SPIRAL2. In chapter 2 the many unanswered questions related to the structure of exotic nuclei are posed and the role of SPIRAL2 in answering them outlined. Chapter 3 deals with the dynamics and thermodynamics of asymmetric nuclear systems. Chapter 4 is concerned with questions of nuclear astrophysics which are intimately related to the properties of exotic nuclei. Chapter 5 indicates how the atomic nucleus can act as a laboratory for tests of the Standard model of Particle Physics and Chapter 6 shows how the production of intense fluxes of neutrons at SPIRAL2 make it an excellent tool to address both questions related to damage in materials of importance in nuclear installations and to the s- and r-processes of nucleosynthesis. In chapter 7 we turn to the application, of the radioactive beams from SPIRAL2 and the radionuclides produced by it, to study condensed matter and radiobiology. Finally in the eight and last chapter the reader can find an account of the historical development of the SPIRAL2 facility and this is followed by an outline of

  15. A Twin Spiral Planar Antenna for UWB Medical Radars

    Directory of Open Access Journals (Sweden)

    Giuseppe A. Zito

    2013-01-01

    Full Text Available A planar-spiral antenna to be used in an ultrawideband (UWB radar system for heart activity monitoring is presented. The antenna, named “twin,” is constituted by two spiral dipoles in a compact structure. The reflection coefficient at the feed point of the dipoles is lower than −8 dB over the 3–12 GHz band, while the two-dipoles coupling is about −20 dB. The radiated beam is perpendicular to the plane of the spiral, so the antenna is wearable and it may be an optimal radiator for a medical UWB radar for heart rate detection. The designed antenna has been also used to check some hypotheses about the UWB radar heart activity detection mechanism. The radiation impedance variation, caused by the thorax vibrations associated with heart activity, seems to be the most likely explanation of the UWB radar operation.

  16. The potentials of spiral CT for detection of focal liver lesions; Moeglichkeiten der Spiral-CT zur Diagnostik fokaler Leberlaesionen

    Energy Technology Data Exchange (ETDEWEB)

    Helmberger, H. [Technische Univ. Muenchen, Klinikum rechts der Iser, Inst. fuer Roentgendiagnostik (Germany); Kersting-Sommerhoff, B. [Technische Univ. Muenchen, Klinikum rechts der Iser, Inst. fuer Roentgendiagnostik (Germany); Lenz, M. [Technische Univ. Muenchen, Klinikum rechts der Iser, Inst. fuer Roentgendiagnostik (Germany); Kirsten, R. [Technische Univ. Muenchen, Klinikum rechts der Iser, Inst. fuer Roentgendiagnostik (Germany); Bautz, W. [Technische Univ. Muenchen, Klinikum rechts der Iser, Inst. fuer Roentgendiagnostik (Germany)

    1996-03-01

    Spiral CT currently is the modality of choice for all aspects of diagnostic evaluation of the liver. Optimal selection of treatment should be based inter alia on the findings obtained by spiral CT with arterial application of contrast medium, as for example S-CTA (primary liver tumors), or S-CTAP (secondary liver tumors). Ultrasonography is the major supplementing modality. In the near future, MR imaging applying liver-specific contrast-enhancing agents is expected to become an important competing technique, and further developments of interest in diagnostic imaging of the liver are in the offing: it is not yet known which technique will be the modality of choice at the onset of the 21st century. (orig.) [Deutsch] Die Spiral-CT ist zur Zeit das empfehlenswerte Verfahren fuer alle Fragen der Leberdiagnostik. Zur optimalen praetherapeutischen Beurteilung der Leber sollte die Spiral-CT mit arterieller Kontrastmittelapplikation als S-CTA (primaere Lebertumoren) bzw. S-CTAP (sekundaere Lebertumoren) durchgefuehrt werden. Der US kommt ein Stellenwert als ergaenzende Methode zu. In Zukunft wird die MRT mit leberspezifischen Kontrastmitteln ein konkurrierendes Verfahren zur Spiral-CT darstellen, wobei eine weitere interessante Entwicklung auf dem Gebiet der hepatischen Bildgebung zu erwarten ist: Das diagnostische Verfahren der Wahl fuer die Leber zu Beginn des 21. Jahrhunderts ist noch nicht definiert. (orig.)

  17. Post-Hartree-Fock studies of the He/Mg(0001) interaction: Anti-corrugation, screening, and pairwise additivity

    Energy Technology Data Exchange (ETDEWEB)

    Lara-Castells, María Pilar de, E-mail: Pilar.deLara.Castells@csic.es [Instituto de Física Fundamental (CSIC), Serrano 123, E-28006 Madrid (Spain); Fernández-Perea, Ricardo [Instituto de Estructura de la Materia (CSIC), Serrano 123, E-28006 Madrid (Spain); Madzharova, Fani; Voloshina, Elena, E-mail: elena.voloshina@hu-berlin.de [Humboldt-Universität zu Berlin, Institut für Chemie, Unter den Linden 6, 10099 Berlin (Germany)

    2016-06-28

    The adsorption of noble gases on metallic surfaces represents a paradigmatic case of van-der-Waals (vdW) interaction due to the role of screening effects on the corrugation of the interaction potential [J. L. F. Da Silva et al., Phys. Rev. Lett. 90, 066104 (2003)]. The extremely small adsorption energy of He atoms on the Mg(0001) surface (below 3 meV) and the delocalized nature and mobility of the surface electrons make the He/Mg(0001) system particularly challenging, even for state-of-the-art vdW-corrected density functional-based (vdW-DFT) approaches [M. P. de Lara-Castells et al., J. Chem. Phys. 143, 194701 (2015)]. In this work, we meet this challenge by applying two different procedures. First, the dispersion-corrected second-order Möller-Plesset perturbation theory (MP2C) approach is adopted, using bare metal clusters of increasing size. Second, the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)] is applied at coupled cluster singles and doubles and perturbative triples level, using embedded cluster models of the metal surface. Both approaches provide clear evidences of the anti-corrugation of the interaction potential: the He atom prefers on-top sites, instead of the expected hollow sites. This is interpreted as a signature of the screening of the He atom by the metal for the on-top configuration. The strong screening in the metal is clearly reflected in the relative contribution of successively deeper surface layers to the main dispersion contribution. Aimed to assist future dynamical simulations, a pairwise potential model for the He/surface interaction as a sum of effective He–Mg pair potentials is also presented, as an improvement of the approximation using isolated He–Mg pairs.

  18. PROTOPLANETARY DISK HEATING AND EVOLUTION DRIVEN BY SPIRAL DENSITY WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Rafikov, Roman R., E-mail: rrr@ias.edu [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)

    2016-11-10

    Scattered light imaging of protoplanetary disks often reveals prominent spiral arms, likely excited by massive planets or stellar companions. Assuming that these arms are density waves, evolving into spiral shocks, we assess their effect on the thermodynamics, accretion, and global evolution of the disk. We derive analytical expressions for the direct (irreversible) heating, angular momentum transport, and mass accretion rate induced by disk shocks of arbitrary amplitude. These processes are very sensitive to the shock strength. We show that waves of moderate strength (density jump at the shock ΔΣ/Σ ∼ 1) result in negligible disk heating (contributing at the ∼1% level to the energy budget) in passive, irradiated protoplanetary disks on ∼100 au scales, but become important within several au. However, shock heating is a significant (or even dominant) energy source in disks of cataclysmic variables, stellar X-ray binaries, and supermassive black hole binaries, heated mainly by viscous dissipation. Mass accretion induced by the spiral shocks is comparable to (or exceeds) the mass inflow due to viscous stresses. Protoplanetary disks featuring prominent global spirals must be evolving rapidly, in ≲0.5 Myr at ∼100 au. A direct upper limit on the evolution timescale can be established by measuring the gravitational torque due to the spiral arms from the imaging data. We find that, regardless of their origin, global spiral waves must be important agents of the protoplanetary disk evolution. They may serve as an effective mechanism of disk dispersal and could be related to the phenomenon of transitional disks.

  19. PROTOPLANETARY DISK HEATING AND EVOLUTION DRIVEN BY SPIRAL DENSITY WAVES

    International Nuclear Information System (INIS)

    Rafikov, Roman R.

    2016-01-01

    Scattered light imaging of protoplanetary disks often reveals prominent spiral arms, likely excited by massive planets or stellar companions. Assuming that these arms are density waves, evolving into spiral shocks, we assess their effect on the thermodynamics, accretion, and global evolution of the disk. We derive analytical expressions for the direct (irreversible) heating, angular momentum transport, and mass accretion rate induced by disk shocks of arbitrary amplitude. These processes are very sensitive to the shock strength. We show that waves of moderate strength (density jump at the shock ΔΣ/Σ ∼ 1) result in negligible disk heating (contributing at the ∼1% level to the energy budget) in passive, irradiated protoplanetary disks on ∼100 au scales, but become important within several au. However, shock heating is a significant (or even dominant) energy source in disks of cataclysmic variables, stellar X-ray binaries, and supermassive black hole binaries, heated mainly by viscous dissipation. Mass accretion induced by the spiral shocks is comparable to (or exceeds) the mass inflow due to viscous stresses. Protoplanetary disks featuring prominent global spirals must be evolving rapidly, in ≲0.5 Myr at ∼100 au. A direct upper limit on the evolution timescale can be established by measuring the gravitational torque due to the spiral arms from the imaging data. We find that, regardless of their origin, global spiral waves must be important agents of the protoplanetary disk evolution. They may serve as an effective mechanism of disk dispersal and could be related to the phenomenon of transitional disks.

  20. Initial clinical experience with spiral CT angiography in the abdomen

    International Nuclear Information System (INIS)

    Gaa, J.; Stehling, M.K.; Costello, P.

    1993-01-01

    The latest developments in modern CT instruments, offering scanning times of a second, opened up new possibilities in CT imaging in combination with the spiral technique. The data set normally taken with single-breath-hold technique is free of respiratory artefacts and thus is a good basis for accurate 3D image reconstruction. Spiral CTA allows a non-invasive 3D imaging of various blood vessels. Patients with abdominal aortic aneurysms of aorto-iliac bypass can be examined as outpatients within 15 minutes. (orig.) [de