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Sample records for prefer cylindrical morphology

  1. Quantitative study of temperature-dependent order in thin films of cylindrical morphology block copolymer

    NASA Astrophysics Data System (ADS)

    Mishra, Vindhya; Kramer, Edward

    2010-03-01

    Disordering and defect generation in block copolymer systems at high temperatures is of significance to get a better understanding of the physics governing these systems, which can also direct efforts to minimize them. We have studied the smectic-nematic-isotropic transition in confined monolayers and bilayers of cylindrical morphology poly (styrene-b-2vinyl pyridine) diblock copolymer. Previous studies of melting phenomena in block copolymer thin films have relied on quantitative AFM studies alone. We have supplemented AFM studies with grazing incidence small angle X-ray diffraction lineshape analysis to quantify the decay of translational and orientational order with increasing temperature. The results have been interpreted in the context of the Toner-Nelson theory of melting for layered systems.

  2. Social Preference in Preschoolers: Effects of Morphological Self-Similarity and Familiarity.

    PubMed

    Richter, Nadja; Tiddeman, Bernard; Haun, Daniel B M

    2016-01-01

    Adults prefer to interact with others that are similar to themselves. Even slight facial self-resemblance can elicit trust towards strangers. Here we investigate if preschoolers at the age of 5 years already use facial self-resemblance when they make social judgments about others. We found that, in the absence of any additional knowledge about prospective peers, children preferred those who look subtly like themselves over complete strangers. Thus, subtle morphological similarities trigger social preferences well before adulthood. PMID:26727132

  3. Social Preference in Preschoolers: Effects of Morphological Self-Similarity and Familiarity

    PubMed Central

    Richter, Nadja; Tiddeman, Bernard; Haun, Daniel B. M.

    2016-01-01

    Adults prefer to interact with others that are similar to themselves. Even slight facial self-resemblance can elicit trust towards strangers. Here we investigate if preschoolers at the age of 5 years already use facial self-resemblance when they make social judgments about others. We found that, in the absence of any additional knowledge about prospective peers, children preferred those who look subtly like themselves over complete strangers. Thus, subtle morphological similarities trigger social preferences well before adulthood. PMID:26727132

  4. Effect of Film Thickness and Domain Spacing on Defect Densities in Directed Self-Assembly of Cylindrical Morphology Block Copolymers

    SciTech Connect

    Mishra, Vindhya; Fredrickson, Glenn H.; Kramer, Edward J.

    2012-04-30

    Directed assembly of block copolymer thin films is recognized as a high-throughput, low-cost complement to optical lithography with the ability to overcome the 32 nm natural resolution limit of conventional lithographic techniques. For bulk block copolymer systems, desired feature sizes ranging from 5 to 100 nm can be obtained by controlling the molecular weight and composition of a block copolymer, as long as the bulk order-disorder temperature (ODT) is such that the copolymer is well-segregated at the processing conditions. However, our studies on graphoepitaxially aligned cylindrical morphology block copolymer monolayer and bilayer films demonstrate that, as domain sizes are reduced, the block copolymer becomes increasingly susceptible to an unacceptably high density of thermally generated defects, resulting in a significant reduction of the ODT. Thus, in thin films, the minimum feature spacing accessible is limited by thermal defect generation and not by the bulk ODT. Our experimental studies on monolayer films of cylindrical morphology polystyrene-b-poly(2-vinyl pyridine) with microdomain spacings approaching 20 nm reveal that defect densities and the ODT are surprisingly sensitive to variations as small as 2 nm in the microdomain spacing. Additionally, the monolayer and bilayer ODT differ by nearly 100 C when the monolayer domain spacing is 20 nm, while the difference is only 20 C when the monolayer domain spacing is 22 nm. We explain this behavior using a quantitative estimation of the energetic cost of defect production in terms of the domain spacing, {chi}N, and block copolymer composition. These studies reveal unexpected consequences on the equilibrium defect densities of thin film block copolymers which must be accounted for when designing a block-copolymer-based directed-assembly process.

  5. A high-accuracy roundness measurement for cylindrical components by a morphological filter considering eccentricity, probe offset, tip head radius and tilt error

    NASA Astrophysics Data System (ADS)

    Sun, Chuanzhi; Wang, Lei; Tan, Jiubin; Zhao, Bo; Zhou, Tong; Kuang, Ye

    2016-08-01

    A morphological filter is proposed to obtain a high-accuracy roundness measurement based on the four-parameter roundness measurement model, which takes into account eccentricity, probe offset, probe tip head radius and tilt error. This paper analyses the sample angle deviations caused by the four systematic errors to design a morphological filter based on the distribution of the sample angle. The effectiveness of the proposed method is verified through simulations and experiments performed with a roundness measuring machine. Compared to the morphological filter with the uniform sample angle, the accuracy of the roundness measurement can be increased by approximately 0.09 μm using the morphological filter with a non-uniform sample angle based on the four-parameter roundness measurement model, when eccentricity is above 16 μm, probe offset is approximately 1000 μm, tilt error is approximately 1″, the probe tip head radius is 1 mm and the cylindrical component radius is approximately 37 mm. The accuracy and reliability of roundness measurements are improved by using the proposed method for cylindrical components with a small radius, especially if the eccentricity and probe offset are large, and the tilt error and probe tip head radius are small. The proposed morphological filter method can be used for precision and ultra-precision roundness measurements, especially for functional assessments of roundness profiles.

  6. Morphology, dimension, and composition dependence of thermodynamically preferred atomic arrangements in Ag-Pt nanoalloys.

    PubMed

    Deng, Lei; Deng, Huiqiu; Xiao, Shifang; Tang, Jianfeng; Hu, Wangyu

    2013-01-01

    The present article is on Metropolis Monte Carlo simulations coupled with semiempirical potentials to obtain the thermodynamically preferred configurations of Ag-Pt nanoalloys. The effects of particle size, morphology or alloy composition on the surface segregation and the chemical ordering patterns were investigated. Surface segregation of Ag is observed in all Ag-Pt nanoalloys. Such segregation develops quickly as the increase of particle sizes or global Ag composition. Generally, Ag surface enrichment is more apparent for more open particles except for large sized icosahedron (ICO) nanoalloys. The most energetically favorable chemical ordering patterns gradually evolve from Pt-core/Ag-shell to onion-like structures when the global Ag composition increases. Due to the site preference of Ag segregation, the presence of partly alloyed facets and Ag blocked vertices or edges at low global Ag compositions can modify the electronic and geometric structures on the nanoalloys' surface. The coupling between Pt and Ag sites is a topic of particular interest for catalysis. The detailed atomistic understanding of atomic arrangements in Ag-Pt nanoalloys is essential to intelligently design robust and active nanocatalysts with a low cost. PMID:24015590

  7. Incompatibility and preferred morphology in the self-accommodation microstructure of β-titanium shape memory alloy

    NASA Astrophysics Data System (ADS)

    Inamura, T.; Hosoda, H.; Miyazaki, S.

    2013-02-01

    The frequency distribution of habit plane variant (HPV) clusters and the deviation from twin orientation relationships (ORs) at the junction plane (JP) are investigated by transmission electron microscopy together with theoretical evaluation of the kinematic compatibility (KC) at the JP in a β-titanium shape memory alloy. Even though there are more than 10 types of possible HPV clusters, only three types are formed. V-shaped couplings of HPVs by {111} type I twins (VI: 49%) and by ⟨211⟩ type II twins (VII: 42%) are the predominant types. A triangular morphology due to coupling of {111} type I twins is observed with a frequency of only 9%. These preferred morphologies are well explained by the degree of incompatibility (the rotation necessary for compatible connection of HPVs). The exact twin OR and KC are maintained at the JP in a VI cluster instead of KC at the habit plane (HP), whereas the JP in a VII cluster is incompatible and the ⟨211⟩ type II twin OR shows slight deviation at the JP by about 0.4°. The competition between KC at the JP and KC at the HP (invariant plane) is responsible for the frequency distribution of HPV clusters and the character of the interfaces in the self-accommodation microstructure.

  8. Cylindrical wormholes

    SciTech Connect

    Bronnikov, K. A.; Lemos, Jose P. S.

    2009-05-15

    It is shown that the existence of static, cylindrically symmetric wormholes does not require violation of the weak or null energy conditions near the throat, and cylindrically symmetric wormhole geometries can appear with less exotic sources than wormholes whose throats have a spherical topology. Examples of exact wormhole solutions are given with scalar, spinor and electromagnetic fields as sources, and these fields are not necessarily phantom. In particular, there are wormhole solutions for a massless, minimally coupled scalar field in the presence of a negative cosmological constant, and for an azimuthal Maxwell electromagnetic field. All these solutions are not asymptotically flat. A no-go theorem is proved, according to which a flat (or string) asymptotic behavior on both sides of a cylindrical wormhole throat is impossible if the energy density of matter is everywhere nonnegative.

  9. Cylindrical Scanner

    Energy Science and Technology Software Center (ESTSC)

    1999-04-29

    The CS system is designed to provide a very fast imaging system in order to search for weapons on persons in an airport environment. The Cylindrical Scanner moves a vertical transceiver array rapidly around a person standing stationary. The software can be segmented in to three specific tasks. The first task is data acquisition and scanner control. At the operator's request, this task commands the scanner to move and the radar transceiver array to sendmore » data to the computer system in a known and well-ordered manner. The array is moved over the complete aperture in 10 to 12 seconds. At the completion of the array movement the second software task automatically reconstructs the high-resolution image from the radar data utilizing the integrated DSP boards. The third task displays the resulting images, as they become available, to the computer screen for user review and analysis.« less

  10. Cylindrical Scanner

    SciTech Connect

    Hall, Thomas E.

    1999-04-29

    The CS system is designed to provide a very fast imaging system in order to search for weapons on persons in an airport environment. The Cylindrical Scanner moves a vertical transceiver array rapidly around a person standing stationary. The software can be segmented in to three specific tasks. The first task is data acquisition and scanner control. At the operator's request, this task commands the scanner to move and the radar transceiver array to send data to the computer system in a known and well-ordered manner. The array is moved over the complete aperture in 10 to 12 seconds. At the completion of the array movement the second software task automatically reconstructs the high-resolution image from the radar data utilizing the integrated DSP boards. The third task displays the resulting images, as they become available, to the computer screen for user review and analysis.

  11. Leaf Morphological Characters Can Be a Factor for Intra-Varietal Preference of Whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) among Eggplant Varieties.

    PubMed

    Hasanuzzaman, Abu Tayeb Mohammad; Islam, Md Nazrul; Zhang, Yi; Zhang, Chen-Yang; Liu, Tong-Xian

    2016-01-01

    The sweetpotato whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae) MEAM1, is considered a serious pest of horticultural and many other crops. While eggplant (Solanum melongena) is one of the most favored host plants, the whiteflies exhibit preferences among different varieties. We hypothesized that certain morphological leaf characteristics of different varieties, like leaf trichome density, trichome length, leaf lamina thickness and leaf color, may affect whitefly landing, feeding and oviposition. In this study, we investigated the variation in leaf morphological characters among selected eggplant varieties and evaluated the effect of these leaf characteristics in rendering eggplant varieties either susceptible or resistant to B. tabaci. We evaluated eight eggplant varieties in choice feeding tests, and we found that the varieties JinSheng Zilongchangqie (JSZ) and H149 were the highly preferred varieties with the highest numbers of whitefly adults and eggs. Significantly lower numbers of whitefly adult eggs were found on the resistant variety Tuo Lu Bamu (TLB). The varieties JinGuangbo Luqie (JGL), JinGuangbo Ziquanqie (JGZ), DaYang Ziguanqie (DYZ), QinXing Ziguanqie (QXZ), and QinXing Niuxinqie (QXN) were moderately favored by B. tabaci. Leaf trichome density, trichome length and leaf lamina thickness were positively correlated with numbers of whitefly adults and eggs. B. tabaci was less attracted to the leaves that reflect long and middle wavelength light (higher R and G values) than to the bright green leaves (medium G value), but the short wavelength light (higher B value) had no significant effect on whitefly preference. The degree of hue had a positive effect, and saturation and brightness had a negative effect on whitefly attraction. PMID:27081849

  12. Leaf Morphological Characters Can Be a Factor for Intra-Varietal Preference of Whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) among Eggplant Varieties

    PubMed Central

    Zhang, Yi; Zhang, Chen-Yang; Liu, Tong-Xian

    2016-01-01

    The sweetpotato whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae) MEAM1, is considered a serious pest of horticultural and many other crops. While eggplant (Solanum melongena) is one of the most favored host plants, the whiteflies exhibit preferences among different varieties. We hypothesized that certain morphological leaf characteristics of different varieties, like leaf trichome density, trichome length, leaf lamina thickness and leaf color, may affect whitefly landing, feeding and oviposition. In this study, we investigated the variation in leaf morphological characters among selected eggplant varieties and evaluated the effect of these leaf characteristics in rendering eggplant varieties either susceptible or resistant to B. tabaci. We evaluated eight eggplant varieties in choice feeding tests, and we found that the varieties JinSheng Zilongchangqie (JSZ) and H149 were the highly preferred varieties with the highest numbers of whitefly adults and eggs. Significantly lower numbers of whitefly adult eggs were found on the resistant variety Tuo Lu Bamu (TLB). The varieties JinGuangbo Luqie (JGL), JinGuangbo Ziquanqie (JGZ), DaYang Ziguanqie (DYZ), QinXing Ziguanqie (QXZ), and QinXing Niuxinqie (QXN) were moderately favored by B. tabaci. Leaf trichome density, trichome length and leaf lamina thickness were positively correlated with numbers of whitefly adults and eggs. B. tabaci was less attracted to the leaves that reflect long and middle wavelength light (higher R and G values) than to the bright green leaves (medium G value), but the short wavelength light (higher B value) had no significant effect on whitefly preference. The degree of hue had a positive effect, and saturation and brightness had a negative effect on whitefly attraction. PMID:27081849

  13. Contrasting shell morphology, ingestion and grazing preferences in the neritid gastropod Smaragdia viridis (L.) on two seagrass species

    NASA Astrophysics Data System (ADS)

    Rueda, José L.; Salas, Carmen; Gofas, Serge

    2011-10-01

    The neritid Smaragdia viridis represents the only known native marine mollusc that feeds on seagrass tissues in the European coasts, displaying a strong association with the seagrasses Cymodocea nodosa and Zostera marina in southern Spain. Seasonal dynamics, shell and radular morphology, growth and feeding of this gastropod have been studied in relation to each seagrass species for contrasting trends resulting from a different type of substrate and food source. In both seagrass species, stable populations of this gastropod occur at similar densities and displaying similar growth rates. Nevertheless shells of individuals from C. nodosa are narrower than those from Z. marina and some differences, possibly a consequence of increased wearing on C. nodosa, were noted amongst the radulae. In C. nodosa, a pre-ingestive selection for young epidermal tissues occurs as it was previously observed in Z. marina. The ingestion rate is higher in C. nodosa than in Z. marina but the absorption of ingested tissues is lower in the former. If both seagrasses are present, most individuals ingested preferentially Z. marina rather than C. nodosa, probably due to the lower digestibility of the epidermal tissues in the latter. Seagrass beds, especially those of Z. marina, are suffering a strong regression in southern Spain and the presence of stable populations of this neritid may be restricted to other declining seagrass species in the area.

  14. Differentiation between cooking bananas and dessert bananas. 1. Morphological and compositional characterization of cultivated Colombian Musaceae (Musa sp.) in relation to consumer preferences.

    PubMed

    Gibert, Olivier; Dufour, Dominique; Giraldo, Andrés; Sánchez, Teresa; Reynes, Max; Pain, Jean-Pierre; González, Alonso; Fernández, Alejandro; Díaz, Alberto

    2009-09-01

    The morphological, physical, and chemical characteristics of 23 unripe cultivated varieties of Colombian Musaceae were assessed. Fresh pulp dry matter helped to discriminate the following consumption subgroups: FHIA dessert hybrids (hydes: 24.6%) < dessert bananas (des: 29.4%) < nonplantain cooking bananas (cook: 32.0%) < FHIA cooking hybrids (hycook: 34.2%) < plantains (pl: 41.1%). Banana flour starch content on dry basis (db) varied from 74.2 to 88.2% among the varieties, with: pl: 86.5% > cook and hycook: 84% > des: 81.9% > hydes: 79.7% (p preferences. PMID:19691321

  15. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2009-12-29

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  16. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2008-04-22

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  17. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2005-06-14

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  18. Cylindrically symmetric wormholes

    SciTech Connect

    Kuhfittig, Peter K.F.

    2005-05-15

    This paper discusses traversable wormholes that differ slightly but significantly from those of the Morris-Thorne type under the assumption of cylindrical symmetry. The throat is a piecewise smooth cylindrical surface resulting in a shape function that is not differentiable at some value. It is proposed that the regular derivative be replaced by a one-sided derivative at this value. The resulting wormhole geometry satisfies the weak energy condition.

  19. Microfabricated cylindrical ion trap

    DOEpatents

    Blain, Matthew G.

    2005-03-22

    A microscale cylindrical ion trap, having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale cylindrical ion trap to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The microscale CIT has a reduced ion mean free path, allowing operation at higher pressures with less expensive and less bulky vacuum pumping system, and with lower battery power than conventional- and miniature-sized ion traps. The reduced electrode voltage enables integration of the microscale cylindrical ion trap with on-chip integrated circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of microscale cylindrical ion traps can be realized in truly field portable, handheld microanalysis systems.

  20. Examining Cylindrical Dice

    ERIC Educational Resources Information Center

    Jones, Dustin L.

    2009-01-01

    The author describes an activity where prospective mathematics teachers made hypotheses about the dimensions of a fair cylindrical die and conducted experiments with different cylinders. He also provides a model that estimates the probability that a cylinder would land on the lateral surface, depending on the height and diameter of the cylinder.…

  1. Cylindrically symmetric electrohydrodynamic patterning.

    PubMed

    Deshpande, Paru; Pease, Leonard F; Chen, Lei; Chou, Stephen Y; Russel, William B

    2004-10-01

    Cylindrically symmetric structures such as concentric rings and rosettes arise out of thin polymeric films subjected to strong electric fields. Experiments that formed concentric rings and theory capable of explaining these and other cylindrical structures are presented. These rings represent an additional member of a class of structures, including pillars and holes, formed by electrohydrodynamic patterning of thin films, occasionally referred to as lithographically induced self-assembly. Fabrication of a set of concentric rings begins by spin coating a thin poly(methyl methacrylate) film onto a silicon wafer. A mask is superimposed parallel to the film leaving a similarly thin air gap. Electric fields, acting in opposition to surface tension, destabilize the free interface when raised above the glass transition temperature. Central pillars nucleate under small cylindrical protrusions patterned on the mask. Rings then emerge sequentially, with larger systems having as many as 10 fully formed rings. Ring-to-ring spacings and annular widths, typically on the order of a micron, are approximately constant within a concentric cluster. The formation rate is proportional to the viscosity and, consequently, has the expected Williams-Landel-Ferry dependence on temperature. In light of these developments we have undertaken a linear stability analysis in cylindrical coordinates to describe these rings and ringlike structures. The salient feature of this analysis is the use of perturbations that incorporate their radial dependence in terms of Bessel functions as opposed to the traditional sinusoids of Cartesian coordinates. The theory predicts approximately constant ring-to-ring spacings, constant annular widths, and growth rates that agree with experiment. A secondary instability is observed at higher temperatures, which causes the rings to segment into arcs or pillar arrays. The cylindrical theory may be generalized to describe hexagonal pillar/hole packing, gratings, and

  2. Cylindrically polarized nondiffracting optical pulses

    NASA Astrophysics Data System (ADS)

    Ornigotti, Marco; Conti, Claudio; Szameit, Alexander

    2016-07-01

    We extend the concept of radially and azimuthally polarized optical beams to the polychromatic domain by introducing cylindrically polarized nondiffracting optical pulses. In particular, we discuss in detail the case of cylindrically polarized X-waves, both in the paraxial and nonparaxial regime. The explicit expressions for the electric and magnetic fields of cylindrically polarized X-waves are also reported.

  3. Static cylindrically symmetric spacetimes

    NASA Astrophysics Data System (ADS)

    Fjällborg, Mikael

    2007-05-01

    We prove the existence of static solutions to the cylindrically symmetric Einstein Vlasov system, and we show that the matter cylinder has finite extension in two of the three spatial dimensions. The same results are also proved for a quite general class of equations of state for perfect fluids coupled to the Einstein equations, extending the class of equations of state considered by Bicak et al (2004 Class. Quantum Grav.21 1583). We also obtain this result for the Vlasov Poisson system.

  4. Conformal approach to cylindrical DLA

    NASA Astrophysics Data System (ADS)

    Taloni, A.; Caglioti, E.; Loreto, V.; Pietronero, L.

    2006-09-01

    We extend the conformal mapping approach elaborated for the radial diffusion limited aggregation model (DLA) to cylindrical geometry. We introduce in particular a complex function which allows a cylindrical cluster to be grown using as an intermediate step a radial aggregate. The aggregate grown exhibits the same self-affine features as the original cylindrical DLA. The specific choice of the transformation allows us to study the relationship between the radial and the cylindrical geometry. In particular the cylindrical aggregate can be seen as a radial aggregate with particles of size increasing with the radius. On the other hand, the radial aggregate can be seen as a cylindrical aggregate with particles of size decreasing with the height. This framework, which shifts the point of view from the geometry to the size of the particles, can open the way to more quantitative studies on the relationship between radial and cylindrical DLA.

  5. Measurement of cylindrical parts

    NASA Astrophysics Data System (ADS)

    Knight, Paul Douglas, Jr.

    The form of cylindrical parts has been traditionally evaluated using stylus-based mechanical instruments. The Tropel Corporation has developed a grazing incidence interferometer (GII) for the measurement of cylindrical parts. The repeatability of this instrument due to various instrument uncertainties was measured. Differing instrument configurations that produce the same systematic error were determined to produce a zonal calibration method for determining systematic error over the full range of the instrument, given knowledge of the error in a single zone. The effect of the aperture stop on the response of the imaging system to axially sinusoidal artifacts was simulated. Diamond-turned axially sinusoidal artifacts, with amplitude of order1 um and spatial wavelength of order10 mm, were measured to test the axial response of the interferometer. The modulation transfer function of the instrument's imaging system, measured using a knife edge test, predicts the response observed with the sinusoidal artifacts. A diffraction analysis predicts that the measured axial form is modified by a second order envelope function with phase that varies with the relative position of the imaging system focal plane and part position. A compensation method is proposed for this effect. A comparison of roundness measurements by both a traditional stylus-based instrument and the GII was performed demonstrating that the roundness measurements of the two instruments are equivalent when the measurements are properly corrected for the differing effects of surface finish.

  6. Cylindrical laser welder

    NASA Astrophysics Data System (ADS)

    Honeycutt, T. E.; Roberts, T. G.

    1986-05-01

    Brass retainer rings are currently fastened to artillery shells by spinning each shell at a high rate and then jamming the ring on it so that it is fastened or welded by friction between the two objects. This is an energy-inefficient process which heats and weakens more material than is desirable. The shell spinning at a high rate is also potentially dangerous. A laser welder is provided that generates output energy focused on a circular or cylindrical shape for simultaneously welding around a 360 degs circumference without unnecessarily heating large amounts of material. The welder may be used to fasten cylindrical shaped objects, gears and shafts together, which is difficult to do by conventional means. The welder may also be used to fasten one cylinder to another. To accomplish the welding, a laser has an unstable optical cavity arranged with its feedback mirror centered to generate a circular output beam having an obscuration in the center. A circularly-symmetric, off-axis concave mirror focuses the output beam onto the objects being fastened and away from the center line or axis of the circular beam.

  7. Cup Cylindrical Waveguide Antenna

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.; Darby, William G.; Kory, Carol L.; Lambert, Kevin M.; Breen, Daniel P.

    2008-01-01

    The cup cylindrical waveguide antenna (CCWA) is a short backfire microwave antenna capable of simultaneously supporting the transmission or reception of two distinct signals having opposite circular polarizations. Short backfire antennas are widely used in mobile/satellite communications, tracking, telemetry, and wireless local area networks because of their compactness and excellent radiation characteristics. A typical prior short backfire antenna contains a half-wavelength dipole excitation element for linear polarization or crossed half-wavelength dipole elements for circular polarization. In order to achieve simultaneous dual circular polarization, it would be necessary to integrate, into the antenna feed structure, a network of hybrid components, which would introduce significant losses. The CCWA embodies an alternate approach that entails relatively low losses and affords the additional advantage of compactness. The CCWA includes a circular cylindrical cup, a circular disk subreflector, and a circular waveguide that serves as the excitation element. The components that make it possible to obtain simultaneous dual circular polarization are integrated into the circular waveguide. These components are a sixpost polarizer and an orthomode transducer (OMT) with two orthogonal coaxial ports. The overall length of the OMT and polarizer (for the nominal middle design frequency of 2.25 GHz) is about 11 in. (approximately equal to 28 cm), whereas the length of a commercially available OMT and polarizer for the same frequency is about 32 in. (approximately equal to 81 cm).

  8. Cylindrical geometry hall thruster

    DOEpatents

    Raitses, Yevgeny; Fisch, Nathaniel J.

    2002-01-01

    An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.

  9. Stage Cylindrical Immersive Display

    NASA Technical Reports Server (NTRS)

    Abramyan, Lucy; Norris, Jeffrey S.; Powell, Mark W.; Mittman, David S.; Shams, Khawaja S.

    2011-01-01

    Panoramic images with a wide field of view intend to provide a better understanding of an environment by placing objects of the environment on one seamless image. However, understanding the sizes and relative positions of the objects in a panorama is not intuitive and prone to errors because the field of view is unnatural to human perception. Scientists are often faced with the difficult task of interpreting the sizes and relative positions of objects in an environment when viewing an image of the environment on computer monitors or prints. A panorama can display an object that appears to be to the right of the viewer when it is, in fact, behind the viewer. This misinterpretation can be very costly, especially when the environment is remote and/or only accessible by unmanned vehicles. A 270 cylindrical display has been developed that surrounds the viewer with carefully calibrated panoramic imagery that correctly engages their natural kinesthetic senses and provides a more accurate awareness of the environment. The cylindrical immersive display offers a more natural window to the environment than a standard cubic CAVE (Cave Automatic Virtual Environment), and the geometry allows multiple collocated users to simultaneously view data and share important decision-making tasks. A CAVE is an immersive virtual reality environment that allows one or more users to absorb themselves in a virtual environment. A common CAVE setup is a room-sized cube where the cube sides act as projection planes. By nature, all cubic CAVEs face a problem with edge matching at edges and corners of the display. Modern immersive displays have found ways to minimize seams by creating very tight edges, and rely on the user to ignore the seam. One significant deficiency of flat-walled CAVEs is that the sense of orientation and perspective within the scene is broken across adjacent walls. On any single wall, parallel lines properly converge at their vanishing point as they should, and the sense of

  10. New optical cylindrical microresonators

    NASA Astrophysics Data System (ADS)

    Gun'ko, Yurii K.; Balakrishnan, Sivakumar; McCarthy, Joseph E.; Rakovich, Yuri P.; Donegan, John F.; Perova, Tatiana S.; Melnikov, Vasily

    2007-10-01

    In this paper we describe a novel technique for the fabrication of aluminosilicate microfibres and microtubes which are shown to act as optical cylindrical microresonators. The alumosilicate microfibres and microtubes were fabricated by using vacuum-assisted wetting and filtration of silica gel through a microchannel glass matrix. The microfibres and microtubes were studied using Scanning Electron Microscopy (SEM), micro-photoluminescence spectroscopy and fluorescence lifetime imaging confocal microscopy. In the emission spectra of the micro-resonators we find very narrow periodic peaks corresponding to the whispering gallery modes of two orthogonal polarizations with quality factors up to 3200. A strong enhancement in photoluminescence decay rates at high excitation power demonstrates the occurrence of amplified spontaneous emission from a single microtube. These microtubes show a large evanescent field extending many microns beyond the tube radius. Potential applications for these novel microresonators will be in the area of optical microsensors for a single molecule detection of biological and chemical species, including anti-terrorism and defense sectors.

  11. Shearfree cylindrical gravitational collapse

    SciTech Connect

    Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.

    2009-09-15

    We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.

  12. Cylindrical Projection of Jupiter

    NASA Technical Reports Server (NTRS)

    1979-01-01

    This computer generated map of Jupiter was made from 10 color images of Jupiter taken Feb. 1, 1979, by Voyager 1, during a single, 10 hour rotation of the planet. Computers at Jet Propulsion Laboratory's Image Processing Lab then turned the photos into this cylindrical projection. Such a projection is invaluable as an instantaneous view of the entire planet. Along the northern edge of the north equatorial belt (NEB) are four dark brown, oblong regions believed by some scientists to be openings in the more colorful upper cloud decks, allowing the darker clouds beneath to be seen. The broad equatorial zone (EZ) is dominated by a series of plumes, possibly regions of intense convective activity, encircling the entire planet. In the southern hemisphere the Great Red Spot is located at about 75 degrees longitude. South of the Great Red Spot in the south temperate zone (STeZ) three large white ovals, seen from Earth-based observatories for the past few decades, are located at 5 degrees, 85 degrees and 170 degrees longitude. Resolution in this map is 375 miles (600 kilometers). Since Jupiter's atmospheric features drift around the planet, longitude is based on the orientation of the planet's magnetic field. Symbols at right edge of photo denote major atmospheric features (dark belts and light zones): NTeZ - north temperate zone; NTrZ - north tropical zone; NEB - north equatorial belt; EZ - equatorial zone; SEB - south equatorial belt; STrZ - south tropical zone; and STeZ - south temperate zone. Voyager belt; EZ - equatorial zone; SEB - south tropical zone; Voyager is managed for NASA's Office of Space Science by Jet Propulsion Laboratory.

  13. Optimization of Cylindrical Hall Thrusters

    SciTech Connect

    Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fi

    2007-07-24

    The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation. __________________________________________________

  14. Optimization of Cylindrical Hall Thrusters

    SciTech Connect

    Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fisch

    2007-11-27

    The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation.

  15. Optical inspection system for cylindrical objects

    DOEpatents

    Brenden, Byron B.; Peters, Timothy J.

    1989-01-01

    In the inspection of cylindrical objects, particularly O-rings, the object is translated through a field of view and a linear light trace is projected on its surface. An image of the light trace is projected on a mask, which has a size and shape corresponding to the size and shape which the image would have if the surface of the object were perfect. If there is a defect, light will pass the mask and be sensed by a detector positioned behind the mask. Preferably, two masks and associated detectors are used, one mask being convex to pass light when the light trace falls on a projection from the surface and the other concave, to pass light when the light trace falls on a depression in the surface. The light trace may be either dynamic, formed by a scanned laser beam, or static, formed by such a beam focussed by a cylindrical lens. Means are provided to automatically keep the illuminating receiving systems properly aligned.

  16. Cylindrical acoustic levitator/concentrator

    DOEpatents

    Kaduchak, Gregory; Sinha, Dipen N.

    2002-01-01

    A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.

  17. Telescoping cylindrical piezoelectric fiber composite actuator assemblies

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

    2010-01-01

    A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

  18. JKR adhesion in cylindrical contacts

    NASA Astrophysics Data System (ADS)

    Sundaram, Narayan; Farris, T. N.; Chandrasekar, S.

    2012-01-01

    Planar JKR adhesive solutions use the half-plane assumption and do not permit calculation of indenter approach or visualization of adhesive force-displacement curves unless the contact is periodic. By considering a conforming cylindrical contact and using an arc crack analogy, we obtain closed-form indenter approach and load-contact size relations for a planar adhesive problem. The contact pressure distribution is also obtained in closed-form. The solutions reduce to known cases in both the adhesion-free and small-contact solution ( Barquins, 1988) limits. The cylindrical system shows two distinct regimes of adhesive behavior; in particular, contact sizes exceeding the critical (maximum) size seen in adhesionless contacts are possible. The effects of contact confinement on adhesive behavior are investigated. Some special cases are considered, including contact with an initial neat-fit and the detachment of a rubbery cylinder from a rigid cradle. A comparison of the cylindrical solution with the half-plane adhesive solution is carried out, and it indicates that the latter typically underestimates the adherence force. The cylindrical adhesive system is novel in that it possesses stable contact states that may not be attained even on applying an infinite load in the absence of adhesion.

  19. Optics Demonstrations Using Cylindrical Lenses

    ERIC Educational Resources Information Center

    Ivanov, Dragia; Nikolov, Stefan

    2015-01-01

    In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…

  20. Vibration of perforated cylindrical shells

    NASA Astrophysics Data System (ADS)

    Cousseau, Peter L.

    For a credible design of an inertial confinement fusion (ICF) target chamber, the vibration characteristics of the chamber must be completely understood. Target chambers are usually cylindrical or spherical in shape and contain hundreds of perforations (called ports) to allow access to the inside of the chamber. The fusion reaction within the chamber creates a uniform impulsive loading, which the chamber walls must be designed to contain. Also prior to an implosion, a delicate alignment process of the drivers and diagnostics takes place. The vibration of the chamber from rotating machinery, e.g., vacuum pumps, and ambient sources must be completely understood and accounted for during these alignment procedures. This dissertation examines the vibration characteristics of perforated cylindrical shells. Because the target chambers' thickness-to-radius ratio is small, such chambers can be modeled as thin shells. Included in the text is a literature review of perforated plates and shells and examples of the use of perforated structures in constructed and proposed ICF target chambers. The natural frequencies and corresponding mode shapes of perforated and unperforated cylindrical shells are studied analytically, numerically (via finite elements) and experimentally. Conclusions and comparisons between the different solution methods are made for both the perforated and unperforated cases. In addition, the dynamic response of perforated cylindrical shells to an axisymmetric impulsive loading has been identified. A demonstration showing how the convolution integral can be used to determine the response of a cylinder to a non-impulsive loading is presented.

  1. Cylindrical magnets and ideal solenoids

    NASA Astrophysics Data System (ADS)

    Derby, Norman; Olbert, Stanislaw

    2010-03-01

    Both wire-wound solenoids and cylindrical magnets can be approximated as ideal azimuthally symmetric solenoids. We present an exact solution for the magnetic field of an ideal solenoid in an easy to use form. The field is expressed in terms of a single function that can be rapidly computed by means of a compact efficient algorithm, which can be coded as an add-in function to a spreadsheet, making field calculations accessible to introductory students. These expressions are not only accurate but are also as fast as most approximate expressions. We demonstrate their utility by simulating the dropping of a cylindrical magnet through a nonmagnetic conducting tube and comparing the calculation with data obtained from experiments suitable for an undergraduate laboratory.

  2. GRIPPING DEVICE FOR CYLINDRICAL OBJECTS

    DOEpatents

    Pilger, J.P.

    1964-01-21

    A gripping device is designed for fragile cylindrical objects such as for drawing thin-walled tubes. The gripping is done by multiple jaw members held in position by two sets of slots, one defined by keystone-shaped extensions of the outer shell of the device and the other in a movable sleeve held slidably by the extensions. Forward movement oi the sleeve advances the jaws, thereby exerting a controlled, radial pressure on the object being gripped. (AEC)

  3. Dynamics of tilted cylindrical geometry

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Sadiq, Sobia

    2016-09-01

    In this paper, we study the dynamics of tilted cylindrical model with imperfect matter distribution. We formulate the field equations and develop relations between tilted and non-tilted variables. We evaluate kinematical as well as dynamical quantities and discuss the inhomogeneity factor. We also obtain the Raychaudhuri equation to study evolution of expansion scalar. The solutions of field equations are also investigated for static cylinder under isotropy and conformally flat condition. Finally, we analyze some thermoinertial aspects of the system.

  4. Cylindrical solutions in mimetic gravity

    NASA Astrophysics Data System (ADS)

    Momeni, Davood; Myrzakulov, Kairat; Myrzakulov, Ratbay; Raza, Muhammad

    2016-06-01

    This paper is devoted to investigate cylindrical solutions in mimetic gravity. The explicit forms of the metric of this theory, namely mimetic-Kasner (say) have been obtained. In this study we have noticed that the Kasner's family of exact solutions needs to be reconsidered under this type of modified gravity. A no-go theorem is proposed for the exact solutions in the presence of a cosmological constant.

  5. Cylindrical solutions in braneworld gravity

    SciTech Connect

    Khoeini-Moghaddam, S.; Nouri-Zonoz, M.

    2005-09-15

    In this article we investigate exact cylindrically symmetric solutions to the modified Einstein field equations in the braneworld gravity scenarios. It is shown that for the special choice of the equation of state 2U+P=0 for the dark energy and dark pressure, the solutions found could be considered formally as solutions of the Einstein-Maxwell equations in 4-D general relativity.

  6. Cylindrical Piezoelectric Fiber Composite Actuators

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

  7. Supercooling Water in Cylindrical Capsules

    NASA Astrophysics Data System (ADS)

    Guzman, J. J. Milón; Braga, S. L.

    2005-11-01

    An experimental apparatus was developed to investigate the supercooling phenomenon of water inside cylindrical capsules used for a cold storage process. The coolant is a water-alcohol mixture controlled by a constant temperature bath (CTB). Temperatures varying with time are measured inside and outside the capsule. Cylinders with an internal diameter and thickness of 45 and 1.5 mm, respectively, were made from four different materials: acrylic, PVC, brass, and aluminum. The supercooling period of the water and the nucleation temperature were investigated for different coolant temperatures. The supercooling and nucleation probabilities are shown as a function of the coolant temperature for the four different materials.

  8. Multi-stable cylindrical lattices

    NASA Astrophysics Data System (ADS)

    Pirrera, Alberto; Lachenal, Xavier; Daynes, Stephen; Weaver, Paul M.; Chenchiah, Isaac V.

    2013-11-01

    We present a cylindrical lattice structure that mimics the behaviour of the virus bacteriophage T4 in having two (or more) stable states which differ in their radii and length. While the virus achieves bistability through molecular mechanisms we use composite materials to exploit the interplay between pre-stress, material properties and structural geometry. We demonstrate (computationally) that multi-stability is a robust phenomenon. We also show (analytically) that it is possible to choose the design variables so that the energy is independent of the radius, thus resulting in every state of the structure being stable.

  9. Chiral structures from achiral liquid crystals in cylindrical capillaries

    PubMed Central

    Jeong, Joonwoo; Kang, Louis; Davidson, Zoey S.; Collings, Peter J.; Lubensky, Tom C.; Yodh, A. G.

    2015-01-01

    We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects. PMID:25825733

  10. Chiral structures from achiral liquid crystals in cylindrical capillaries.

    PubMed

    Jeong, Joonwoo; Kang, Louis; Davidson, Zoey S; Collings, Peter J; Lubensky, Tom C; Yodh, A G

    2015-04-14

    We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects. PMID:25825733

  11. Chiral structures from achiral liquid crystals in cylindrical capillaries

    NASA Astrophysics Data System (ADS)

    Jeong, Joonwoo; Kang, Louis; Davidson, Zoey S.; Collings, Peter J.; Lubensky, Tom C.; Yodh, A. G.

    2015-04-01

    We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects.

  12. Models of cylindrical bubble pulsation

    PubMed Central

    Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hay, Todd A.; Hamilton, Mark F.

    2012-01-01

    Three models are considered for describing the dynamics of a pulsating cylindrical bubble. A linear solution is derived for a cylindrical bubble in an infinite compressible liquid. The solution accounts for losses due to viscosity, heat conduction, and acoustic radiation. It reveals that radiation is the dominant loss mechanism, and that it is 22 times greater than for a spherical bubble of the same radius. The predicted resonance frequency provides a basis of comparison for limiting forms of other models. The second model considered is a commonly used equation in Rayleigh-Plesset form that requires an incompressible liquid to be finite in extent in order for bubble pulsation to occur. The radial extent of the liquid becomes a fitting parameter, and it is found that considerably different values of the parameter are required for modeling inertial motion versus acoustical oscillations. The third model was developed by V. K. Kedrinskii [Hydrodynamics of Explosion (Springer, New York, 2005), pp. 23–26] in the form of the Gilmore equation for compressible liquids of infinite extent. While the correct resonance frequency and loss factor are not recovered from this model in the linear approximation, it provides reasonable agreement with observations of inertial motion. PMID:22978863

  13. Loads for pulsed power cylindrical implosion experiments

    SciTech Connect

    Anderson, W.E.; Armijo, E.V.; Barthell, B.L.; Bartos, J.J.; Bush, H.; Foreman, L.R.; Garcia, F.P.; Gobby, P.L.; Gomez, V.M.; Gurule, V.A.

    1994-07-01

    Pulse power can be used to generate high energy density conditions in convergent hollow cylindrical geometry through the use of appropriate electrode configuration and cylindrical loads. Cylindrically symmetric experiments are conducted with the Pegasus-H inductive store, capacitor energized pulse power facility at Los Alamos using both precision machined cylindrical liner loads and low mass vapor deposited cylindrical foil loads. The liner experiments investigate solid density hydrodynamic topics. Foil loads vaporize from Joule heating to generate an imploding cylindrical plasma which can be used to simulate some fluxes associated with fusion energy processes. Similar experiments are conducted with {open_quotes}Procyon{close_quotes} inductive store pulse power assemblies energized by explosively driven magnetic flux compression.

  14. Propagation Mechanism of Cylindrical Cellular Detonation

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  15. How Are Preferences Revealed?

    PubMed Central

    Beshears, John; Choi, James J.; Laibson, David; Madrian, Brigitte C.

    2009-01-01

    Revealed preferences are tastes that rationalize an economic agent’s observed actions. Normative preferences represent the agent’s actual interests. It sometimes makes sense to assume that revealed preferences are identical to normative preferences. But there are many cases where this assumption is violated. We identify five factors that increase the likelihood of a disparity between revealed preferences and normative preferences: passive choice, complexity, limited personal experience, third-party marketing, and intertemporal choice. We then discuss six approaches that jointly contribute to the identification of normative preferences: structural estimation, active decisions, asymptotic choice, aggregated revealed preferences, reported preferences, and informed preferences. Each of these approaches uses consumer behavior to infer some property of normative preferences without equating revealed and normative preferences. We illustrate these issues with evidence from savings and investment outcomes. PMID:24761048

  16. Observations of ion-acoustic cylindrical solitons

    NASA Technical Reports Server (NTRS)

    Hershkowitz, N.; Romesser, T.

    1974-01-01

    Experimental observations of cylindrical solitons in a collisionless plasma are presented. The data obtained show that cylindrical solitonlike objects exist and that their properties are consistent with those of one- and three-dimensional solitons. It is found that compressive density perturbations evolve into solitons. The number of the solitons is determined by the width and amplitude of the applied pulse.

  17. Transitivity of Preferences

    ERIC Educational Resources Information Center

    Regenwetter, Michel; Dana, Jason; Davis-Stober, Clintin P.

    2011-01-01

    Transitivity of preferences is a fundamental principle shared by most major contemporary rational, prescriptive, and descriptive models of decision making. To have transitive preferences, a person, group, or society that prefers choice option "x" to "y" and "y" to "z" must prefer "x" to "z". Any claim of empirical violations of transitivity by…

  18. Growing Yeast into Cylindrical Colonies

    PubMed Central

    Vulin, Clément; Di Meglio, Jean-Marc; Lindner, Ariel B.; Daerr, Adrian; Murray, Andrew; Hersen, Pascal

    2014-01-01

    Microorganisms often form complex multicellular assemblies such as biofilms and colonies. Understanding the interplay between assembly expansion, metabolic yield, and nutrient diffusion within a freely growing colony remains a challenge. Most available data on microorganisms are from planktonic cultures, due to the lack of experimental tools to control the growth of multicellular assemblies. Here, we propose a method to constrain the growth of yeast colonies into simple geometric shapes such as cylinders. To this end, we designed a simple, versatile culture system to control the location of nutrient delivery below a growing colony. Under such culture conditions, yeast colonies grow vertically and only at the locations where nutrients are delivered. Colonies increase in height at a steady growth rate that is inversely proportional to the cylinder radius. We show that the vertical growth rate of cylindrical colonies is not defined by the single-cell division rate, but rather by the colony metabolic yield. This contrasts with cells in liquid culture, in which the single-cell division rate is the only parameter that defines the population growth rate. This method also provides a direct, simple method to estimate the metabolic yield of a colony. Our study further demonstrates the importance of the shape of colonies on setting their expansion. We anticipate that our approach will be a starting point for elaborate studies of the population dynamics, evolution, and ecology of microbial colonies in complex landscapes. PMID:24853750

  19. Filling of charged cylindrical capillaries.

    PubMed

    Das, Siddhartha; Chanda, Sourayon; Eijkel, J C T; Tas, N R; Chakraborty, Suman; Mitra, Sushanta K

    2014-10-01

    We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because of decreased velocity gradients at the wall. Both these effects essentially stem from the spontaneous formation of an electric double layer (EDL) and the resulting streaming potential caused by the net capillary-flow-driven advection of ionic species within the EDL. Our results demonstrate that filling of charged capillaries also exhibits the well-known linear and Washburn regimes witnessed for uncharged capillaries, although the filling rate is always lower than that of the uncharged capillary. We attribute this to a competitive success of the lowering of the driving forces (because of electroviscous effects), in comparison to the effect of weaker drag forces. We further reveal that the time at which the transition between the linear and the Washburn regime occurs may become significantly altered with the introduction of surface charges, thereby altering the resultant capillary dynamics in a rather intricate manner. PMID:25375597

  20. Intrinsic cylindrical and spherical waves

    NASA Astrophysics Data System (ADS)

    Ludlow, I. K.

    2008-02-01

    Intrinsic waveforms associated with cylindrical and spherical Bessel functions are obtained by eliminating the factors responsible for the inverse radius and inverse square radius laws of wave power per unit area of wavefront. The resulting expressions are Riccati-Bessel functions for both cases and these can be written in terms of amplitude and phase functions of order v and wave variable z. When z is real, it is shown that a spatial phase angle of the intrinsic wave can be defined and this, together with its amplitude function, is systematically investigated for a range of fixed orders and varying z. The derivatives of Riccati-Bessel functions are also examined. All the component functions exhibit different behaviour in the near field depending on the order being less than, equal to or greater than 1/2. Plots of the phase angle can be used to display the locations of the zeros of the general Riccati-Bessel functions and lead to new relations concerning the ordering of the real zeros of Bessel functions and the occurrence of multiple zeros when the argument of the Bessel function is fixed.

  1. Crack problems in cylindrical and spherical shells

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1976-01-01

    Standard plate or shell theories were used as a starting point to study the fracture problems in thin-walled cylindrical and spherical shells, assuming that the plane of the crack is perpendicular to the surface of the sheet. Since recent studies have shown that local shell curvatures may have a rather considerable effect on the stress intensity factor, the crack problem was considered in conjunction with a shell rather than a plate theory. The material was assumed to be isotropic and homogeneous, so that approximate solutions may be obtained by approximating the local shell crack geometry with an ideal shell which has a solution, namely a spherical shell with a meridional crack, a cylindrical shell with a circumferential crack, or a cylindrical shell with an axial crack. A method of solution for the specially orthotropic shells containing a crack was described; symmetric and skew-symmetric problems are considered in cylindrical shells with an axial crack.

  2. Rotational preference in gymnastics.

    PubMed

    Heinen, Thomas; Jeraj, Damian; Vinken, Pia M; Velentzas, Konstantinos

    2012-06-01

    In gymnastics, most skills incorporate rotations about one or more body axes. At present, the question remains open if factors such as lateral preference and/or vestibulo-spinal asymmetry are related to gymnast's rotational preference. Therefore, we sought to explore relationships in gymnast's rotation direction between different gymnastic skills. Furthermore, we sought to explore relationships between rotational preference, lateral preference, and vestibulo-spinal asymmetry. In the experiment n = 30 non-experts, n = 30 near-experts and n = 30 experts completed a rotational preference questionnaire, a lateral preference inventory, and the Unterberger-Fukuda Stepping Test. The results revealed, that near-experts and experts more often rotate rightward in the straight jump with a full turn when rotating leftward in the round-off and vice versa. The same relationship was found for experts when relating the rotation preference in the handstand with a full turn to the rotation preference in the straight jump with a full turn. Lateral preference was positively related to rotational preference in non-expert gymnasts, and vestibulo-spinal asymmetry was positively related to rotational preference in experts. We suggest, that gymnasts should explore their individual rotational preference by systematically practicing different skills with a different rotation direction, bearing in mind that a clearly developed structure in rotational preference between different skills may be appropriate to develop more complex skills in gymnastics. PMID:23486362

  3. Rotational Preference in Gymnastics

    PubMed Central

    Heinen, Thomas; Jeraj, Damian; Vinken, Pia M.; Velentzas, Konstantinos

    2012-01-01

    In gymnastics, most skills incorporate rotations about one or more body axes. At present, the question remains open if factors such as lateral preference and/or vestibulo-spinal asymmetry are related to gymnast’s rotational preference. Therefore, we sought to explore relationships in gymnast’s rotation direction between different gymnastic skills. Furthermore, we sought to explore relationships between rotational preference, lateral preference, and vestibulo-spinal asymmetry. In the experiment n = 30 non-experts, n = 30 near-experts and n = 30 experts completed a rotational preference questionnaire, a lateral preference inventory, and the Unterberger-Fukuda Stepping Test. The results revealed, that near-experts and experts more often rotate rightward in the straight jump with a full turn when rotating leftward in the round-off and vice versa. The same relationship was found for experts when relating the rotation preference in the handstand with a full turn to the rotation preference in the straight jump with a full turn. Lateral preference was positively related to rotational preference in non-expert gymnasts, and vestibulo-spinal asymmetry was positively related to rotational preference in experts. We suggest, that gymnasts should explore their individual rotational preference by systematically practicing different skills with a different rotation direction, bearing in mind that a clearly developed structure in rotational preference between different skills may be appropriate to develop more complex skills in gymnastics. PMID:23486362

  4. View factors of cylindrical spiral surfaces

    NASA Astrophysics Data System (ADS)

    Lebedev, Vladimir A.; Solovjov, Vladimir P.

    2016-03-01

    Analytical expressions are presented for the view factors (radiative configuration factors) associated with the flat right cylindrical spiral surface. Such cylindrical spiral systems are widely applied as electrical resistance heating elements for lighting devices, electronic radio tubes, high-speed gas flow heaters, and other appliances used for scientific, industrial and domestic purposes. Derivation of the view factors is based on the invariant principles and the results presented in Lebedev (2000, 2003,1988) [1-3].

  5. Damage experiments in cylindrical geometry update

    SciTech Connect

    Kaul, Anne; Holtkamp, David; Rodriguez, George

    2009-01-01

    Using a cylindrical configuration to study spallation damage allows for a natural recollection of the damaged material under proper driving conditions. Previous experiments provided data about failure initiation in aluminum in a cylindrical geometry and the behavior of material recollected after damage from pressures in the damage initiation regime. The current series of experiments studied the behavior of material recollected after complete failure. Results from the current experiments will be presented.

  6. Smectic-A structures in submicrometer cylindrical cavities

    NASA Astrophysics Data System (ADS)

    Kralj, S.; Žumer, S.

    1996-08-01

    Model structures of a smectic-A liquid crystal confined to a long cylindrical cavity enforcing homeotropic surface anchoring are studied theoretically. The structures are obtained numerically through minimization of the Landau-de Gennes type free energy. We limit our discussion to cylinders with submicrometer radia. Five qualitatively different smectic-A configurations are proposed: the smectic-planar-radial, smectic-escaped-radial, chevron, bookshelf, and hybrid structures. Our analysis suggests that in the strong anchoring regime the smectic-escaped-radial structure is the most stable. For this structure relatively large temperature shifts of the nematic-smectic-A phase transition are expected. In the weak anchoring regime the chevron and bookshelf structures are found to be the most stable. We demonstrate that smectic elasticity can cause strong deviations from the preferred surface anchoring direction.

  7. Simulating flow and segregation of cylindrical particles

    NASA Astrophysics Data System (ADS)

    Zhao, Yongzhi; Umbanhowar, Paul B.; Lueptow, Richard M.

    2015-11-01

    Efficient and accurate simulation of cylindrical particles using discrete element method (DEM) is a challenge. Typical approaches to simulating cylindrical particle systems are based on the glued spheres method, which has low accuracy, or real shape models, which have high computational cost. In this work we utilize super-ellipsoids, which belong to super-quadrics, to model cylindrical particles in DEM simulations. Simulations of a single cylinder impacting a flat wall indicate that super-ellipsoids provide the same accuracy as real shape models and much better accuracy than the glued sphere method. Simulations of super-ellipsoid cylindrical particles in rotating tumblers result in nearly the same angle of repose as experiments and real shape simulations, demonstrating the accuracy of super-ellipsoid DEM simulations for multi-particle systems. The segregation of bidisperse cylindrical particles differing in length in a bounded heap was simulated by super-ellipsoid DEM, and the results are similar to the experiment. In spite of these advantages of using super-ellipsoid cylindrical particles, simulations of filling a box with particles indicate that the simulation times for super-ellipsoid cylinders is about an order of magnitude longer than that for the same number of spherical particles.

  8. Measuring Children's Food Preferences.

    ERIC Educational Resources Information Center

    Birch, Leann L.; Sullivan, Susan A.

    1991-01-01

    Measures of preference are useful predictors of children's food consumption patterns. The paper discusses children's affective response to food and describes the preference assessment procedure which obtains information on children's likes and dislikes. The methodology helps investigate factors influencing development of preferences and food…

  9. Solid particle impingement erosion characteristics of cylindrical surfaces, pre-existing holes and slits

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Buckley, D. H.

    1983-01-01

    The erosion characteristics of aluminum cylinders sand-blasted with both spherical and angular erodent particles were studied and compared with results from previously studied flat surfaces. The cylindrical results are discussed with respect to impact conditions. The relationship between erosion rate and pit morphology (width, depth, and width to depth ratio) is established. The aspects of (1) erosion rate versus time curves on cylindrical surfaces; (2) long-term exposures; and (3) erosion rate versus time curves with spherical and angular particles are presented. The erosion morphology and characteristics of aluminum surfaces with pre-existing circular cylindrical and conical holes of different sizes were examined using weight loss measurements, scanning electron microscopy, a profilometer, and a depth gage. The morphological features (radial and concentric rings) are discussed with reference to flat surfaces, and the erosion features with spherical microglass beads. The similarities and differences of erosion and morphological features are highlighted. The erosion versus time curves of various shapes of holes are discussed and are compared with those of a flat surface. The erosion process at slits is considered.

  10. The Dizzying Depths of the Cylindrical Mirror

    NASA Astrophysics Data System (ADS)

    DeWeerd, Alan J.; Hill, S. Eric

    2005-02-01

    A typical introduction to geometrical optics treats plane and spherical mirrors. At first glance, it may be surprising that texts seldom mention the cylindrical mirror, except for the occasional reference to use in fun houses and to viewing anamorphic art.1,2 However, even a cursory treatment reveals its complexity. Holzberlein used an extended object to qualitatively illustrate that images are produced both before and behind a concave cylindrical mirror.3 He also speculated on how this extreme astigmatism results in an observer's dizziness. By considering a simple point object, we make a more detailed analysis of the cylindrical mirror and the dizziness it induces. First, we illustrate how rays from a point object reflect to form not one point image but two line images. Next, we describe how an observer perceives a likeness of the object. Finally, we suggest how confusing depth cues induce dizziness. Although we focus on the concave cylindrical mirror, the discussion is easy to generalize to the convex cylindrical mirror.

  11. Thin Film Instabilities in Blends under Cylindrical Confinement.

    PubMed

    Chen, Dian; Chen, Jiun-Tai; Glogowski, Elizabeth; Emrick, Todd; Russell, Thomas P

    2009-02-18

    Rayleigh instabilities in bilayers of poly(methyl methacrylate) (PMMA) and polystyrene (PS) confined within the cylindrical nanoporous anodic aluminum oxide (AAO) membranes were investigated. The bilayered nanotubes were thermally annealed to induce phase separation and instabilities in the confined films. For short annealing times, the nanotubes were transformed into nanorods with periodic encapsulated air pockets. With longer annealing times, the air-pockets coalesced to form columns of air. Small air inclusions encased in periodic domains of PS were, in turn, incorporated within PMMA nanorods. Selectively removing the PMMA by exposure to UV radiation and washing with acetic acid, left PS nanospheres with an air inclusion. Gold nanoparticles having PS ligands were also incorporated within the PS phase, generating novel composite morphologies. PMID:21706613

  12. Laser diode assembly including a cylindrical lens

    DOEpatents

    Snyder, J.J.; Reichert, P.

    1992-01-14

    The present invention provides a diffraction limited, high numerical aperture (fast) cylindrical microlens. The method for making the microlens is adaptable to produce a cylindrical lens that has almost any shape on its optical surfaces. The cylindrical lens may have a shape, such as elliptical or hyperbolic, designed to transform some particular given input light distribution into some desired output light distribution. In the method, the desired shape is first formed in a glass preform. Then, the preform is heated to the minimum drawing temperature and a fiber is drawn from it. The cross-sectional shape of the fiber bears a direct relation to the shape of the preform from which it was drawn. During the drawing process, the surfaces become optically smooth due to fire polishing. 11 figs.

  13. Laser diode assembly including a cylindrical lens

    DOEpatents

    Snyder, James J.; Reichert, Patrick

    1992-01-01

    The present invention provides a diffraction limited, high numerical aperture (fast) cylindrical microlens. The method for making the microlens is adaptable to produce a cylindrical lens that has almost any shape on its optical surfaces. The cylindrical lens may have a shape, such as elliptical or hyperbolic, designed to transform some particular given input light distribution into some desired output light distribution. In the method, the desired shape is first formed in a glass preform. Then, the preform is heated to the minimum drawing temperature and a fiber is drawn from it. The cross-sectional shape of the fiber bears a direct relation to the shape of the preform from which it was drawn. During the drawing process, the surfaces become optically smooth due to fire polishing.

  14. Current pulse effects on cylindrical damage experiments

    SciTech Connect

    Kaul, Ann M; Rousculp, Christopher L

    2009-01-01

    A series of joint experiments between LANL and VNIIEF use a VNIIEF-designed helical generator to provide currents for driving a LANL-designed cylindrical spallation experimental load. Under proper driving conditions, a cylindrical configuration allows for a natural recollection of the damaged material. In addition, the damaged material is able to come to a complete stop due to its strength, avoiding application of further forces. Thus far, experiments have provided data about failure initiation of a well-characterized material (aluminum) in a cylindrical geometry, behavior of material recollected after damage from pressures in the damage initiation regime, and behavior of material recollected after complete failure. In addition to post-shot collection of the damaged target material for subsequent metallographic analysis, dynamic in-situ experimental diagnostics include velocimetry and transverse radial radiography. This paper will focus on the effects of tailoring the driving current pulse to obtain the desired data.

  15. Light scattering from cylindrical structures on surfaces.

    PubMed

    Taubenblatt, M A

    1990-03-01

    Light scattering from a dielectric cylindrical structure on a surface by a plane wave with field vector along the cylinder axis is calculated with a modification of the coupled-dipole method. The interaction matrix is calculated with the use of both the direct contribution of a polarization current filament and its reflection from the surface. The reflected cylindrical waves are computed with the use of the Sommerfeld-type integral expression. Light scattering from structures of arbitrary cross section and the size of the order of a wavelength can be quickly determined with this method. PMID:19759774

  16. Self-referenced interferometer for cylindrical surfaces.

    PubMed

    Šarbort, Martin; Řeřucha, Šimon; Holá, Miroslava; Buchta, Zdeněk; Lazar, Josef

    2015-11-20

    We present a new interferometric method for shape measurement of hollow cylindrical tubes. We propose a simple and robust self-referenced interferometer where the reference and object waves are represented by the central and peripheral parts, respectively, of the conical wave generated by a single axicon lens. The interferogram detected by a digital camera is characterized by a closed-fringe pattern with a circular carrier. The interference phase is demodulated using spatial synchronous detection. The capabilities of the interferometer are experimentally tested for various hollow cylindrical tubes with lengths up to 600 mm. PMID:26836560

  17. Roots of sex preference.

    PubMed

    Lee H-t; Choe, E H

    1982-12-01

    This paper provides a brief overview of not yet fully analyzed 1974 World Fertility Survey for Korea data on sex preference, and also parental gender role stereotyping and gender preference, as they relate to sex preference and fertility behavior of the individual parents of childbearing age. The data includes the mother's background and numbers of children desired. Fertility preferences reflect sociocultural, economic and psychological aspects of individual parents' habits and perceptions of the world. Attitude, which is difficult to measure, is often connected to and can predict behavior. Age, residence, educational level, and spouse's occupation are related. Sex preference for sons is affected by how many parents hope to send a son to college (75.2%), compared to those hoping to send a daughter to college (52%). Parents under 25 also prefer boys. Gender preference is the pattern of sociocultural behavior associated with the awareness of being masculine or feminine. Sex preference is the patterns arising from the biological fact of being male or female. A 1981 son preference survey covered the province of Kyongbuk, conservative in gender preference, polling 832 women, ages 15 to 49. The survey covered questions about gender associated activities, occupations and personality traits. These items were divided into 4 gender role discriminant scales, covering most and least masculine or feminine degrees within each category. Respondents with less extreme gender role stereotyping are less sex biased; extreme sex preference is closely related to the respondents' extreme gender role stereotypic traits. Korean society has conferred differential value upon gender specific work and the main criterion for the division of labor is gender, not biological sex. This contributes to a parent's sex preferential attitude, which is unlikely to change without a modification of premodern neoconfucian gender based behaviors. PMID:12264918

  18. Optical methods for cylindrical rough surface testing

    NASA Astrophysics Data System (ADS)

    Perez Quintian, F.; Rebollo, Maria A.; Gaggioli, Nestor G.; Raffo, C. A.

    1999-07-01

    This work studies theoretically the scattering of light from cylindrical rough surfaces. It is shown, for the conical diffraction configuration, that the mean intensity on an observation plane perpendicular to the cylinder longitudinal axis, is related to the statistical parameters that characterize the surface: the roughness (sigma) and the correlation length T.

  19. Distributed neural signals on parabolic cylindrical shells

    NASA Astrophysics Data System (ADS)

    Hu, S. D.; Li, H.; Tzou, H. S.

    2013-06-01

    Parabolic cylindrical shells are commonly used as key components in communication antennas, space telescopes, solar collectors, etc. This study focuses on distributed modal neural sensing signals on a flexible simply-supported parabolic cylindrical shell panel. The parabolic cylindrical shell is fully laminated with a piezoelectric layer on its outer surface and the piezoelectric layer is segmented into infinitesimal elements (neurons) to investigate the microscopic distributed neural sensing signals. Since the dominant vibration component of the shell is usually the transverse oscillation, a new transverse mode shape function is defined. Two shell cases, i.e., the ratio of the meridian height to the half span distance of a parabola at 1:4 (shallow) and 1:1 (deep), are studied to reveal the curvature effect to the neural sensing signals. Studies suggest that the membrane signal component dominates for lower natural modes and the bending signal component dominates for higher natural modes. The meridional membrane and bending signal components are mostly concentrated on the high-curvature areas, while the longitudinal bending component is mostly concentrated on the relatively flat areas. The concentration behavior becomes more prominent as the parabolic cylindrical shell deepens, primarily resulting from the enhanced membrane effect due to the increased curvature.

  20. Conformal cylindrically symmetric spacetimes in modified gravity

    NASA Astrophysics Data System (ADS)

    Türkog˜lu, Murat Metehan; Dog˜ru, Melis Ulu

    2015-11-01

    We investigate cylindrically symmetric spacetimes in the context of f(R) gravity. We firstly attain conformal symmetry of the cylindrically symmetric spacetime. We obtain solutions to use features of the conformal symmetry, field equations and their solutions for cylindrically symmetric spacetime filled with various cosmic matters such as vacuum state, perfect fluid, anisotropic fluid, massive scalar field and their combinations. With the vacuum state solutions, we show that source of the spacetime curvature is considered as Casimir effect. Casimir force for given spacetime is found using Wald’s axiomatic analysis. We expose that the Casimir force for Boulware, Hartle-Hawking and Unruh vacuum states could have attractive, repulsive and ineffective features. In the perfect fluid state, we show that matter form of the perfect fluid in given spacetime must only be dark energy. Also, we offer that potential of massive and massless scalar field are developed as an exact solution from the modified field equations. All solutions of field equations for vacuum case, perfect fluid and scalar field give a special f(R) function convenient to Λ-CDM model. In addition to these solutions, we introduce conformal cylindrical symmetric solutions in the cases of different f(R) models. Finally, geometrical and physical results of the solutions are discussed.

  1. Light Transmission Through Reflecting Cylindrical Tubes

    ERIC Educational Resources Information Center

    Cohen, D. K.; Potts, J. E.

    1978-01-01

    Describes an experiment in which a point source of light, when viewed through a cylindrical tube having reflecting inner walls, appears as a series of sharply defined rings, due to the multiple reflections from the inner walls of the tube. ( GA)

  2. Cylindrical Induction Melter Modicon Control System

    SciTech Connect

    Weeks, G.E.

    1998-04-01

    In the last several years an extensive R{ampersand}D program has been underway to develop a vitrification system to stabilize Americium (Am) and Curium (Cm) inventories at SRS. This report documents the Modicon control system designed for the 3 inch Cylindrical Induction Melter (CIM).

  3. Tamm plasmon polaritons in multilayered cylindrical structures

    NASA Astrophysics Data System (ADS)

    Little, C. E.; Anufriev, R.; Iorsh, I.; Kaliteevski, M. A.; Abram, R. A.; Brand, S.

    2012-12-01

    It is shown that cylindrical Bragg reflector structures with either a metal core, a metal cladding, or both can support Tamm plasmon polaritons (TPPs) that can propagate axially along the interface between the metallic layer and the adjacent dielectric. A transfer matrix formalism for cylindrical multilayered structures is used in association with cavity phase matching considerations to design structures that support Tamm plasmon polaritons at specified frequencies, and to explore the field distributions and the dispersion relations of the excitations. The cylindrical TPPs can exist in both the TE and TM polarizations for the special cases of modes with either azimuthal isotropy or zero axial propagation constant and also as hybrid cylindrical modes when neither of those conditions applies. In the cases considered the TPPs have low effective masses and low group velocities. Also, when there is both metallic core and cladding, near degenerate modes localized at each metallic interface can couple to produce symmetric and antisymmetric combinations whose frequency difference is in the terahertz regime.

  4. Class Scheduling Preferences.

    ERIC Educational Resources Information Center

    Richards, Irving E.; And Others

    In order to ascertain students' preferences for the number of times a class should meet each week, 375 questionnaires administered to students during the 1989 summer session at Cuyahoga Community College, Western Campus (Ohio) were evaluated. Results indicated that 49% of respondents preferred classes meeting twice each week, and 29% preferred…

  5. The Learning Preference Inventory.

    ERIC Educational Resources Information Center

    Rezler, Agnes G.; Rezmovic, Victor

    1981-01-01

    Describes the development, validity, and reliability of the Learning Preference Inventory (LPI) and its use with health professions students and practitioners. Use of the LPI allows identification of individual learning preferences with a fair degree of accuracy. Ways to improve motivation for learning are suggested. (JOW)

  6. Synthetic aperture imaging for multilayer cylindrical object using an exterior rotating transducer

    NASA Astrophysics Data System (ADS)

    Wu, Shiwei; Skjelvareid, Martin H.; Yang, Keji; Chen, Jian

    2015-08-01

    The synthetic aperture focusing technique (SAFT) with significant improvements in lateral resolution has been adapted for ultrasound imaging of multilayer objects. To apply SAFT to imaging of cylindrical objects such as solid axles or pipes with small diameter, exterior cylindrical scan is much preferred. In this paper, a frequency-domain algorithm is proposed for such cylindrical scan performed with an exterior rotating transducer. The algorithm is derived from Fourier-domain solutions to the waveequation in cylindrical coordinates, and then extended to the multilayer case. A simulation model for multilayer structure is established, and the algorithm is demonstrated for both simulated and experimental data. Compared with the raw images, the reconstructed images with proposed algorithm attain better lateral resolution for multilayer objects. It is shown that the attainable angular resolution for each layer is approximately consistent with that achieved in the single-layer case, as long as the transmission factors are approximately uniform within the divergence angle of the transducer. The performance of proposed algorithm is verified with experimental C-scan image and demonstrates that it is capable of improving the lateral resolution in both scanning directions.

  7. Synthetic aperture imaging for multilayer cylindrical object using an exterior rotating transducer.

    PubMed

    Wu, Shiwei; Skjelvareid, Martin H; Yang, Keji; Chen, Jian

    2015-08-01

    The synthetic aperture focusing technique (SAFT) with significant improvements in lateral resolution has been adapted for ultrasound imaging of multilayer objects. To apply SAFT to imaging of cylindrical objects such as solid axles or pipes with small diameter, exterior cylindrical scan is much preferred. In this paper, a frequency-domain algorithm is proposed for such cylindrical scan performed with an exterior rotating transducer. The algorithm is derived from Fourier-domain solutions to the waveequation in cylindrical coordinates, and then extended to the multilayer case. A simulation model for multilayer structure is established, and the algorithm is demonstrated for both simulated and experimental data. Compared with the raw images, the reconstructed images with proposed algorithm attain better lateral resolution for multilayer objects. It is shown that the attainable angular resolution for each layer is approximately consistent with that achieved in the single-layer case, as long as the transmission factors are approximately uniform within the divergence angle of the transducer. The performance of proposed algorithm is verified with experimental C-scan image and demonstrates that it is capable of improving the lateral resolution in both scanning directions. PMID:26329199

  8. Musical morphology.

    PubMed

    Chakravarty, M Mallar; Vuust, Peter

    2009-07-01

    Morphologic measures have long been used to determine the patho-anatomical signature of different neurologic disorders. However, these measures can also be used to determine effects of specific learning tasks and quantifiable human abilities on cerebral structure. Musicians provide interesting opportunities for this type of analysis as their various skills, such as rhythmic ability and pitch and harmony discrimination (acquired through years of practicing and playing) can be quantified and compared using distinct morphologic analyses. Here, we review magnetic resonance imaging-based morphologic analyses in the music and neuroscience literature and provide some results from our own analysis of rhythmic ability in a cohort of musicians. PMID:19673757

  9. Gravitational radiation from a cylindrical naked singularity

    SciTech Connect

    Nakao, Ken-ichi; Morisawa, Yoshiyuki

    2005-06-15

    We construct an approximate solution which describes the gravitational emission from a naked singularity formed by the gravitational collapse of a cylindrical thick shell composed of dust. The assumed situation is that the collapsing speed of the dust is very large. In this situation, the metric variables are obtained approximately by a kind of linear perturbation analysis in the background Morgan solution which describes the motion of cylindrical null dust. The most important problem in this study is what boundary conditions for metric and matter variables should be imposed at the naked singularity. We find a boundary condition that all the metric and matter variables are everywhere finite at least up to the first order approximation. This implies that the spacetime singularity formed by this high-speed dust collapse is very similar to that formed by the null dust and the final singularity will be a conical one. Weyl curvature is completely released from the collapsed dust.

  10. Quantum Cylindrical Waves and Parametrized Field Theory

    NASA Astrophysics Data System (ADS)

    Varadarajan, Madhavan

    In this article, we review some illustrative results in the study of two related toy models for quantum gravity, namely cylindrical waves (which are cylindrically symmetric gravitational fields)and parametrized field theory (which is just free scalar field theory on a flat space-time in generally covariant disguise). In the former, we focus on the phenomenon of unexpected large quantum gravity effects in regions of weak classical gravitational fields and on an analysis of causality in a quantum geometry. In the latter, we focus on Dirac quantization, argue that this is related to the unitary implementability of free scalar field evolution along curved foliations of the flat space-time and review the relevant results for unitary implementability.

  11. Nonaxisymmetric radiative transfer in cylindrical enclosures

    SciTech Connect

    Moder, J.P.; Lee, H.S.; Chai, J.C.; Parthasarathy, G.; Patankar, S.V.

    1996-12-31

    A finite-volume method for radiative transfer in cylindrical enclosures is presented. Angular redistribution terms in the equation of transfer are avoided by defining radiation directions in terms of angular coordinates measured with respect to Cartesian base vectors; this definition of radiation directions can result in control angles which overlap control-volume faces, depending on the type of spatial and angular grids used in the azimuthal direction. A simple treatment for such control-angle overlaps is presented which is also applicable to nonorthogonal curvilinear spatial-coordinates. A comparison of the present procedure with other similar methods is given. Solutions are presented for axisymmetric transfer through a cylinder and nonaxisymmetric transfer through two- and three-dimensional annular sectors. Results show that the procedure produces reasonable solutions for transparent and participating media in axisymmetric and nonaxisymmetric cylindrical enclosures.

  12. Surface superconductivity in thin cylindrical Bi nanowire.

    PubMed

    Tian, Mingliang; Wang, Jian; Ning, Wei; Mallouk, Thomas E; Chan, Moses H W

    2015-03-11

    The physical origin and the nature of superconductivity in nanostructured Bi remains puzzling. Here, we report transport measurements of individual cylindrical single-crystal Bi nanowires, 20 and 32 nm in diameter. In contrast to nonsuperconducting Bi nanoribbons with two flat surfaces, cylindrical Bi nanowires show superconductivity below 1.3 K. However, their superconducting critical magnetic fields decrease with their diameter, which is the opposite of the expected behavior for thin superconducting wires. Quasiperiodic oscillations of magnetoresistance were observed in perpendicular fields but were not seen in the parallel orientation. These results can be understood by a model of surface superconductivity with an enhanced surface-to-bulk volume in small diameter wires, where the superconductivity originates from the strained surface states of the nanowires due to the surface curvature-induced stress. PMID:25658139

  13. Damage experiments in a cylindrical geometry

    SciTech Connect

    Kaul, Ann M

    2010-09-21

    Studying spallation damage with a cylindrical configuration allows for a natural recollection of the damaged material under proper driving conditions. Additionally, the damaged material can come to a complete rest without the application of further stopping forces. Specific areas of research include the damage initiation regime in convergent geometry, behavior of material recollected after damage, and effects of convergent geometry on the material response. Such experiments produce unique strain and shear stress states, motivating improvements in existing computational material models and increasing the predictive capabilities of codes. A LANL/VNIIEF joint experimental series has produced cylindrical aluminum failure initiation data and studied the behavior of material recollected after damage initiation and after complete failure. In addition to post-shot collection of the damaged target material for subsequent metallographic analysis, dynamic in-situ experimental diagnostics include velocimetry and transverse radial radiography. This paper will discuss the current experimental status.

  14. Jamming of Cylindrical Grains in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; Spier, Gregory; Barr, Nicholas; Steel, Fiona

    2012-02-01

    We study jamming of low aspect-ratio cylindrical Delrin grains in a vertical channel. These cylindrical grains resemble antacid tablets, poker chips, or coins since their height is less than their diameter. Grains are allowed to fall through a vertical channel with a square cross section where the channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. Within this channel, grains are sometimes observed to form jams, stable structures supported by the channel walls with no support beneath them. The probability of jam occurrence and the strength or robustness of a jam is effected by the grain dimensions and channel size. We will present experimental measurements of the jamming probability and jam strength in this system and discuss the relationship of these results to other experiments and theories.

  15. Multiple Bifurcations of a Cylindrical Dynamical System

    NASA Astrophysics Data System (ADS)

    Han, Ning; Cao, Qingjie

    2016-03-01

    This paper focuses on multiple bifurcations of a cylindrical dynamical system, which is evolved from a rotating pendulum with SD oscillator. The rotating pendulum system exhibits the coupling dynamics property of the bistable state and conventional pendulum with the ho- moclinic orbits of the first and second type. A double Andronov-Hopf bifurcation, two saddle-node bifurcations of periodic orbits and a pair of homoclinic bifurcations are detected by using analytical analysis and nu- merical calculation. It is found that the homoclinic orbits of the second type can bifurcate into a pair of rotational limit cycles, coexisting with the oscillating limit cycle. Additionally, the results obtained herein, are helpful to explore different types of limit cycles and the complex dynamic bifurcation of cylindrical dynamical system.

  16. Omnidirectional, circularly polarized, cylindrical microstrip antenna

    NASA Technical Reports Server (NTRS)

    Stanton, Philip H. (Inventor)

    1985-01-01

    A microstrip cylindrical antenna comprised of two concentric subelements on a ground cylinder, a vertically polarized (E-field parallel to the axis of the antenna cylinder) subelement on the inside and a horizontally polarized (E-field perpendicular to the axis) subelement on the outside. The vertical subelement is a wraparound microstrip radiator. A Y-shaped microstrip patch configuration is used for the horizontally polarized radiator that is wrapped 1.5 times to provide radiating edges on opposite sides of the cylindrical antenna for improved azimuthal pattern uniformity. When these subelements are so fed that their far fields are equal in amplitude and phased 90.degree. from each other, a circularly polarized EM wave results. By stacking a plurality of like antenna elements on the ground cylinder, a linear phased array antenna is provided that can be beam steered to the desired elevation angle.

  17. Buckling optimisation of sandwich cylindrical panels

    NASA Astrophysics Data System (ADS)

    Abouhamzeh, M.; Sadighi, M.

    2016-06-01

    In this paper, the buckling load optimisation is performed on sandwich cylindrical panels. A finite element program is developed in MATLAB to solve the governing differential equations of the global buckling of the structure. In order to find the optimal solution, the genetic algorithm Toolbox in MATLAB is implemented. Verifications are made for both the buckling finite element code and also the results from the genetic algorithm by comparisons to the results available in literature. Sandwich cylindrical panels are optimised for the buckling strength with isotropic or orthotropic cores with different boundary conditions. Results are presented in terms of stacking sequence of fibers in the face sheets and core to face sheet thickness ratio.

  18. Cylindrically converging blast waves in air

    NASA Astrophysics Data System (ADS)

    Matsuo, H.; Nakamura, Y.

    1981-07-01

    Cylindrically converging shock waves are produced by utilizing the detonation of cylindrical explosive shells. The production and the propagation of shock waves are observed by framing and streak camera photographs, and the trajectory of shock propagations is determined by using an electrical ionization probing system. The effect of the quantity of explosives on the stability, or the axial symmetry, of shock fronts and on the strength of shocks produced is investigated. It has been shown that, for practical purposes, the approximation of shock trajectories by Guderley's formulas would be sufficiently acceptable in an unexpectedly wide region near the implosion center, and that the axial symmetry of the shock front is improved by increasing the quantity of explosives, and thus, strong shocks are produced by merely increasing the quantity of explosives. The reflected diverging shock seems to be very stable. Piezoelectric elements have also been used to detect reflected diverging waves.

  19. Nanolaminate Membranes as Cylindrical Telescope Reflectors

    NASA Technical Reports Server (NTRS)

    Dooley, Jennifer; Dragovan, Mark; Hickey, Gregory; Lih, Shyh-Shiu Lih

    2010-01-01

    A document discusses a proposal to use axially stretched metal nanolaminate membranes as lightweight parabolic cylindrical reflectors in the Dual Anamorphic Reflector Telescope (DART) - a planned spaceborne telescope in which the cylindrical reflectors would be arranged to obtain a point focus. The discussion brings together a combination of concepts reported separately in several prior NASA Tech Briefs articles, the most relevant being "Nanolaminate Mirrors With Integral Figure-Control Actuators" NPO -30221, Vol. 26, No. 5 (May 2002), page 90; and "Reflectors Made From Membranes Stretched Between Beams" NPO -30571, Vol. 33, No. 10 (October 2009), page 11a. The engineering issues receiving the greatest emphasis in the instant document are (1) the change in curvature associated with the Poisson contraction of a stretched nanolaminate reflector membrane and (2) the feasibility of using patches of poly(vinylidene fluoride) on the rear membrane surface as piezoelectric actuators to correct the surface figure for the effect of Poisson contraction and other shape errors.

  20. Preferred Orientation in Polymer Fiber Scattering

    SciTech Connect

    Burger, C.; Hsiao , B; Chu, B

    2010-01-01

    Fiber symmetry is one of the most important sample geometries encountered in both wide-angle x-ray scattering (WAXS) and small-angle x-ray scattering (SAXS) of polymers, applicable both to natural polymers like collagen or cellulose and to many synthetic polymers that come in fiber form or otherwise exhibit cylindrical rotational symmetry. The structural information to be determined in scattering experiments from such fiber systems includes both the structure of the individual structural unit and qualitative and quantitative information about the preferred orientation state of the ensemble. Existing approaches and new developments to analyze fiber scattering patterns are rigorously reviewed. Special emphasis is placed on the calculation of complete SAXS and WAXS fiber scattering patterns, and various practical examples including collagen and cellulose fibers as well as fibers based on copolymers of polyethylene and polypropylene are discussed.

  1. Machining Thin-Walled Cylindrical Parts

    NASA Technical Reports Server (NTRS)

    Cimbak, Joe; Spagnolo, Jim; Kraus, Dan

    1988-01-01

    Cylindrical walls only few thousandths of inch thick machined accurately and without tears or punctures with aid of beryllium copper mandrel. Chilled so it contracts, then inserted in cylinder. As comes to room temperature, mandrel expands and fits snugly inside cylinder. Will not allow part to slide and provides solid backup to prevent deflection when part machined by grinding wheel. When machining finished, cylinder-and-mandrel assembly inserted in dry ice, mandrel contracts and removed from part.

  2. Domain wall dynamics in cylindrical nanomagnet

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Soumik; Singh, Amrita; Ghosh, Arindam

    2011-06-01

    The stochasticity associated with domain wall nucleation and propagation in a cylinderical nanowire has been studied using time resolved resistance measurement in presence of magnetic field. We have shown that the propagation stochasticity of domain wall in a cylindrical nanowire is reflected in the magnetic field dependent velocity distribution whereas the stochasticity involved in the domain wall nucleation can be effectively tuned by varying the angle between the direction of applied magnetic field and the long axis of the cylinder.

  3. Moiré effect in cylindrical objects

    NASA Astrophysics Data System (ADS)

    Saveljev, Vladimir

    2016-05-01

    The moiré effect in single-walled cylindrical objects (gridshells) is investigated. The surface of such an object is a rolled-up periodic grating (mesh). Analytical formulae are obtained for the period of the moiré patterns, which depends particularly on the direction of the wavevector of the grating. The experiments confirm the theory. The results can be applied to nanoparticles and to three-dimensional autostereoscopic displays.

  4. Numerical dynamo action in cylindrical containers

    NASA Astrophysics Data System (ADS)

    Nore, Caroline; Castanon Quiroz, Daniel; Guermond, Jean-Luc; Léorat, Jacques; Luddens, Francky

    2015-06-01

    The purpose of this paper is to present results from numerical simulations of dynamo action in relation with two magnetohydrodynamics (MHD) experiments using liquid sodium in cylindrical containers. The first one is the von Kármán sodium (VKS) experiment from Cadarache (France), the second one is a precession-driven dynamo experiment from the DREsden sodium facility for DYNamo and thermohydraulic studies (DRESDYN). Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014) - Elected submissions", edited by Adel Razek

  5. Electronic quantum confinement in cylindrical potential well

    NASA Astrophysics Data System (ADS)

    Baltenkov, Arkadiy S.; Msezane, Alfred Z.

    2016-04-01

    The effects of quantum confinement on the momentum distribution of electrons confined within a cylindrical potential well have been analyzed. The motivation is to understand specific features of the momentum distribution of electrons when the electron behavior is completely controlled by the parameters of a non-isotropic potential cavity. It is shown that studying the solutions of the wave equation for an electron confined in a cylindrical potential well offers the possibility to analyze the confinement behavior of an electron executing one- or two-dimensional motion in the three-dimensional space within the framework of the same mathematical model. Some low-lying electronic states with different symmetries have been considered and the corresponding wave functions have been calculated; the behavior of their nodes and their peak positions with respect to the parameters of the cylindrical well has been analyzed. Additionally, the momentum distributions of electrons in these states have been calculated. The limiting cases of the ratio of the cylinder length H and its radius R0 have been considered; when the cylinder length H significantly exceeds its radius R0 and when the cylinder radius is much greater than its length. The cylindrical quantum confinement effects on the momentum distribution of electrons in these potential wells have been analyzed. The possible application of the results obtained here for the description of the general features in the behavior of electrons in nanowires with metallic type of conductivity (or nanotubes) and ultrathin epitaxial films (or graphene sheets) are discussed. Possible experiments are suggested where the quantum confinement can be manifested. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by Gerardo Delgado Barrio, Andrey Solov'Yov, Pablo Villarreal, Rita Prosmiti.

  6. Cylindrical multilayer metal-dielectric structures

    NASA Astrophysics Data System (ADS)

    Sasin, M. E.; Il'inskaya, N. D.; Zadiranov, Yu. M.; Kaliteevskaya, N. A.; Lazarenko, A. A.; Mazlin, V. A.; Brunkov, P. N.; Pavlov, S. I.; Kaliteevski, M. A.

    2015-11-01

    A method of creating a cylindrical structures consisting of thin metallic layer and dielectric multilayer Bragg reflector is described. Formation of the structures is observed experimentally as a result of separation and twisting away from the substrate a thin layer of gold coated with a multilayer SiO2/TiO2 Bragg reflector. It is suggested that such structures may be of interest for the creation of novel optoelectronic devices.

  7. A printed circuit cylindrical array antenna

    NASA Astrophysics Data System (ADS)

    Agrawal, Ashok K.; Powell, Walter E.

    1986-11-01

    The design and performance of a Ku-band cylindrical antenna are described. The antenna is designed to provide a 360-deg azimuth coverage with 20-dB sidelobes and an operating bandwidth of 1 GHz (16.0-17.0 GHz). The antenna consists of 16 facets of 2 x 4 dipole arrays. The 360-deg coverage is obtained with a switch matrix network. The antenna elements and the feeding switch matrix network are printed on a single printed circuit board.

  8. Mach disc formation in cylindrical recovery systems

    SciTech Connect

    Morris, C.E.; McQueen, R.G.; Marsh, S.P.

    1983-01-01

    Cylindrical recovery systems have been used to shock-load polymers to pressures exceeding 50 GPa. In order to determine the pressures generated in these recovery systems the formation of the Mach disc on axis and its approach to steady state was monitored. The relation of the Mach disc diameter to the lateral dimension of the high explosive used to compress the polymer samples was also investigated.

  9. Effectiveness of the magnetostatic shielding by the cylindrical shells

    NASA Astrophysics Data System (ADS)

    Grabchikov, S. S.; Trukhanov, A. V.; Trukhanov, S. V.; Kazakevich, I. S.; Solobay, A. A.; Erofeenko, V. T.; Vasilenkov, N. A.; Volkova, O. S.; Shakin, A.

    2016-01-01

    The experimental research of the magnetostatic shielding effectiveness and the analytical calculations of the average magnetic permeability of single-layer cylindrical sample of the shields based on electrolytically deposited Ni80Fe20 alloy are carried out. The locations of maxima on the Ef(H) and μ(H) curves do not match each other, which is difficult to interpret in terms of the shunting model. The results are explained by the non-linear distribution of the magnetic permeability through the thickness of the shield. It has been shown that in the magnetic fields range from 100 A/m up to 2700 A/m, the shields based on the Ni80Fe20 alloy are preferred over ones based on the 84KHSR amorphous ribbon. It is concluded that at the selection of shield materials it should take into account not only the main magnetic characteristics - μ; Hs; Hc but also Hmax parameter, which is important to evaluate the effectiveness of magnetic shielding.

  10. Fabrication Studies for a Cylindrical DDS Structure at 90 GHz

    SciTech Connect

    Bowden, G.B.; Chou, P.J.; Kirby, R.E.; Menegat, A.; Siemann, R.H.; Spencer, J.E.; Wang, J.W.; /SLAC

    2011-08-26

    A natural extension of work on the next generation of high power RF sources and accelerating cavities for Linear Colliders implies cylindrical, damped, detuned structures for millimeter wavelengths. Commercial availability of WR-10 waveguides and other components in the 75-110 GHz range provides a practical goal. Fabrication methods are surveyed, compared and, in some cases, tested to determine whether they can provide the imposed tolerances. Different techniques and tolerances are compared to previous methods at longer wavelengths. The higher gradients and corresponding surface fields indicate that a better understanding of the surface physics is required as well as how the different fabrication steps influence those surface characteristics that impact the final operation. We consider existing systems at SLAC and elsewhere as a function of frequency to determine what is desirable to measure and control for all phases of the fabrication, testing, conditioning and use of these systems. For example, the importance of crystal structure to the different steps is discussed. The preferred method allows a variety of design alternatives to be pursued simultaneously and extends to shorter wavelengths as well as provides possibilities for embedded test and control elements.

  11. The preference for potential.

    PubMed

    Tormala, Zakary L; Jia, Jayson S; Norton, Michael I

    2012-10-01

    When people seek to impress others, they often do so by highlighting individual achievements. Despite the intuitive appeal of this strategy, we demonstrate that people often prefer potential rather than achievement when evaluating others. Indeed, compared with references to achievement (e.g., "this person has won an award for his work"), references to potential (e.g., "this person could win an award for his work") appear to stimulate greater interest and processing, which can translate into more favorable reactions. This tendency creates a phenomenon whereby the potential to be good at something can be preferred over actually being good at that very same thing. We document this preference for potential in laboratory and field experiments, using targets ranging from athletes to comedians to graduate school applicants and measures ranging from salary allocations to online ad clicks to admission decisions. PMID:22775472

  12. [Food preferences among students].

    PubMed

    Maldonado, R; Villalbí, J R

    1993-07-01

    The results of a food preference survey using a questionnaire on 2,567 schoolchildren of sixth, seventh and eighth grade (11 to 14 years of age) from 26 public schools in the city of Barcelona (Spain) are presented. Foods based on potatoes and cereals have the maximum acceptability, followed by dairy and meat products. Chicken is the meat with highest acceptance. Fish has a medium acceptance, and preference for dry beans and peas, fruits and vegetables is lower, although it is high for some specific foods. Important differences among sexes are observed. Boys have higher preference for meat, milk and yogurt, and girls for fish and some vegetables. Differences among genders increase with increasing age. These results are relevant for planning interventions on diet in schools from a health promotion perspective, and for the planning of school lunch programs. PMID:8363142

  13. Cylindrical nonlinear Schroedinger equation versus cylindrical Korteweg-de Vries equation

    SciTech Connect

    Fedele, Renato; De Nicola, Sergio; Grecu, Dan; Visinescu, Anca; Shukla, Padma K.

    2008-10-15

    A correspondence between the family of cylindrical nonlinear Schroedinger (cNLS) equations and the one of cylindrical Korteweg-de Vries (cKdV) equations is constructed. It associates non stationary solutions of the first family with the ones of the second family. This is done by using a correspondence, recently found, between the families of generalized NLS equation and generalized KdV equation, and their solutions in the form of travelling waves, respectively. In particular, non-stationary soliton-like solutions of the cNLS equation can be associated with non-stationary soliton-like solutions of cKdV equation.

  14. Metal Preferences and Metallation*

    PubMed Central

    Foster, Andrew W.; Osman, Deenah; Robinson, Nigel J.

    2014-01-01

    The metal binding preferences of most metalloproteins do not match their metal requirements. Thus, metallation of an estimated 30% of metalloenzymes is aided by metal delivery systems, with ∼25% acquiring preassembled metal cofactors. The remaining ∼70% are presumed to compete for metals from buffered metal pools. Metallation is further aided by maintaining the relative concentrations of these pools as an inverse function of the stabilities of the respective metal complexes. For example, magnesium enzymes always prefer to bind zinc, and these metals dominate the metalloenzymes without metal delivery systems. Therefore, the buffered concentration of zinc is held at least a million-fold below magnesium inside most cells. PMID:25160626

  15. Motion parallax in immersive cylindrical display systems

    NASA Astrophysics Data System (ADS)

    Filliard, N.; Reymond, G.; Kemeny, A.; Berthoz, A.

    2012-03-01

    Motion parallax is a crucial visual cue produced by translations of the observer for the perception of depth and selfmotion. Therefore, tracking the observer viewpoint has become inevitable in immersive virtual (VR) reality systems (cylindrical screens, CAVE, head mounted displays) used e.g. in automotive industry (style reviews, architecture design, ergonomics studies) or in scientific studies of visual perception. The perception of a stable and rigid world requires that this visual cue be coherent with other extra-retinal (e.g. vestibular, kinesthetic) cues signaling ego-motion. Although world stability is never questioned in real world, rendering head coupled viewpoint in VR can lead to the perception of an illusory perception of unstable environments, unless a non-unity scale factor is applied on recorded head movements. Besides, cylindrical screens are usually used with static observers due to image distortions when rendering image for viewpoints different from a sweet spot. We developed a technique to compensate in real-time these non-linear visual distortions, in an industrial VR setup, based on a cylindrical screen projection system. Additionally, to evaluate the amount of discrepancies tolerated without perceptual distortions between visual and extraretinal cues, a "motion parallax gain" between the velocity of the observer's head and that of the virtual camera was introduced in this system. The influence of this artificial gain was measured on the gait stability of free-standing participants. Results indicate that, below unity, gains significantly alter postural control. Conversely, the influence of higher gains remains limited, suggesting a certain tolerance of observers to these conditions. Parallax gain amplification is therefore proposed as a possible solution to provide a wider exploration of space to users of immersive virtual reality systems.

  16. Radiation of sound from unflanged cylindrical ducts

    NASA Technical Reports Server (NTRS)

    Hartharan, S. L.; Bayliss, A.

    1983-01-01

    Calculations of sound radiated from unflanged cylindrical ducts are presented. The numerical simulation models the problem of an aero-engine inlet. The time dependent linearized Euler equations are solved from a state of rest until a harmonic solution is attained. A fourth order accurate finite difference scheme is used and solutions are obtained from a fully vectorized Cyber-203 computer program. Cases of both plane waves and spin modes are treated. Spin modes model the sound generated by a turbofan engine. Boundary conditions for both plane waves and spin modes are treated. Solutions obtained are compared with experiments conducted at NASA Langley Research Center.

  17. High convergence implosion symmetry in cylindrical hohlraums

    SciTech Connect

    Amendt, P A; Bradley, D K; Hammel, B A; Landen, O L; Suter, L J; Turner, R E; Wallace, R J

    1999-09-01

    High convergence, hohlraum-driven implosions will require control of time-integrated drive asymmetries to 1% levels for ignition to succeed on the NIF. We review how core imaging provides such asymmetry measurement accuracy for the lowest order asymmetry modes, and describe recent improvements in imaging techniques that should allow detection of higher order asymmetry modes. We also present a simple analytic model explaining how the sensitivity of symmetry control to beam pointing scales as we progress from single ring per side Nova cylindrical hohlraum illumination geometries to NIF-like multiple rings per side Omega hohlraum illumination geometries and ultimately to NIF-scale hohlraums.

  18. Enhanced Performance of Cylindrical Hall Thrusters

    SciTech Connect

    Y. Raitses, A. Smirnov, and N.J. Fisch

    2007-05-14

    The cylindrical thruster differs significantly in its underlying physical mechanisms from the conventional annular Hall thruster. It features high ionization efficiency, quiet operation, ion acceleration in a large volume-to-surface ratio channel, and performance comparable with the state-of-the-art conventional Hall thrusters. Very significant plume narrowing, accompanied by the increase of the energetic ion fraction and improvement of ion focusing, led to 50%–60% increase of the thruster anode efficiency. These improvements were achieved by overrunning the discharge current in the magnetized thruster plasma.

  19. Enhanced performance of cylindrical Hall thrusters

    SciTech Connect

    Raitses, Y.; Smirnov, A.; Fisch, N. J.

    2007-05-28

    The cylindrical thruster differs significantly in its underlying physical mechanisms from the conventional annular Hall thruster. It features high ionization efficiency, quiet operation, ion acceleration in a large volume-to-surface ratio channel, and performance comparable with the state-of-the-art conventional Hall thrusters. Very significant plume narrowing, accompanied by the increase of the energetic ion fraction and improvement of ion focusing, led to 50%-60% increase of the thruster anode efficiency. These improvements were achieved by overrunning the discharge current in the magnetized thruster plasma.

  20. Liquid crystal alignment in cylindrical microcapillaries

    NASA Astrophysics Data System (ADS)

    Chychłowski, M.; Yaroshchuk, O.; Kravchuk, R.; Woliński, T.

    2011-09-01

    A variety of alignment configurations of liquid crystals (LCs) inside the glassy cylindrical capillaries is realized by using alignment materials providing different anchoring. The radial configuration with central disclination line is obtained for homeotropic boundary conditions. In turn, the axial, transversal and tilted alignment structures are realized by using materials for planar anchoring. The uniformity and controlling of the latter structures were provided by photoalignment method. This approach can be further used to control LC alignment in the photonic crystal fibers recognized as advanced elements for different optical devices.

  1. Liquid crystal alignment in cylindrical microcapillaries

    NASA Astrophysics Data System (ADS)

    Chychłowski, M.; Yaroshchuk, O.; Kravchuk, R.; Woliński, T.

    2012-03-01

    A variety of alignment configurations of liquid crystals (LCs) inside the glassy cylindrical capillaries is realized by using alignment materials providing different anchoring. The radial configuration with central disclination line is obtained for homeotropic boundary conditions. In turn, the axial, transversal and tilted alignment structures are realized by using materials for planar anchoring. The uniformity and controlling of the latter structures were provided by photoalignment method. This approach can be further used to control LC alignment in the photonic crystal fibers recognized as advanced elements for different optical devices.

  2. Preferring the Contemporary Look.

    ERIC Educational Resources Information Center

    Springer, Marc

    1980-01-01

    Describes a study that indicated that readers of college newspapers prefer a front page style that is contemporary and emphasizes a horizontal layout to either an avant-garde style that features an entirely horizontal layout or a traditional layout having a vertical page. (TJ)

  3. Cognitive Preferences and Ethnicity.

    ERIC Educational Resources Information Center

    O'Donnell, William J.; O'Donnell, Teresa Flores

    This document reports on a study into the relationships between cognitive preferences, achievement, and ethnicity of first year algebra students. The sample consisted of 175 students from two high schools in the Denver (Colorado) metropolitan area. The two schools were chosen because of the diversity of ethnic groups in the student populations.…

  4. QUANTITATIVE MORPHOLOGY

    EPA Science Inventory

    Abstract: In toxicology, the role of quantitative assessment of brain morphology can be understood in the context of two types of treatment-related alterations. One type of alteration is specifically associated with treatment and is not observed in control animals. Measurement ...

  5. Thermal stress in high temperature cylindrical fasteners

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.

    1988-01-01

    Uninsulated structures fabricated from carbon or silicon-based materials, which are allowed to become hot during flight, are attractive for the design of some components of hypersonic vehicles. They have the potential to reduce weight and increase vehicle efficiency. Because of manufacturing contraints, these structures will consist of parts which must be fastened together. The thermal expansion mismatch between conventional metal fasteners and carbon or silicon-based structural materials may make it difficult to design a structural joint which is tight over the operational temperature range without exceeding allowable stress limits. In this study, algebraic, closed-form solutions for calculating the thermal stresses resulting from radial thermal expansion mismatch around a cylindrical fastener are developed. These solutions permit a designer to quickly evaluate many combinations of materials for the fastener and the structure. Using the algebraic equations developed, material properties and joint geometry were varied to determine their effect on thermal stresses. Finite element analyses were used to verify that the closed-form solutions derived give the correct thermal stress distribution around a cylindrical fastener and to investigate the effect of some of the simplifying assumptions made in developing the closed-form solutions for thermal stresses.

  6. Design parameters for rotating cylindrical filtration

    NASA Technical Reports Server (NTRS)

    Schwille, John A.; Mitra, Deepanjan; Lueptow, Richard M.

    2002-01-01

    Rotating cylindrical filtration displays significantly reduced plugging of filter pores and build-up of a cake layer, but the number and range of parameters that can be adjusted complicates the design of these devices. Twelve individual parameters were investigated experimentally by measuring the build-up of particles on the rotating cylindrical filter after a fixed time of operation. The build-up of particles on the filter depends on the rotational speed, the radial filtrate flow, the particle size and the gap width. Other parameters, such as suspension concentration and total flow rate are less important. Of the four mechanisms present in rotating filters to reduce pore plugging and cake build-up, axial shear, rotational shear, centrifugal sedimentation and vortical motion, the evidence suggests rotational shear is the dominant mechanism, although the other mechanisms still play minor roles. The ratio of the shear force acting parallel to the filter surface on a particle to the Stokes drag acting normal to the filter surface on the particle due to the difference between particle motion and filtrate flow can be used as a non-dimensional parameter that predicts the degree of particle build-up on the filter surface for a wide variety of filtration conditions. c2002 Elsevier Science B.V. All rights reserved.

  7. Data fusion for cylindrical form measurements

    NASA Astrophysics Data System (ADS)

    Liu, Pei; Jusko, Otto; Tutsch, Rainer

    2015-12-01

    For high-precision form measurements of cylindrical workpieces form profiles such as roundness and straightness profiles are independently acquired via a bird-cage strategy. The 3D point cloud reconstructed by fusing these intersected profiles is meaningful in dimension and form assessment for cylinder, since enhanced accuracy can be achieved by fusion results. Moreover, it plays an important role as the input to other calculations. However, these data cannot be accurately aligned in form reconstruction, due to random absolute offsets in profiles and a lack of absolute positions. Therefore, we propose an approach to data fusion of these profiles to reconstruct cylindrical form. The uncertainties of the fused profile are evaluated, taking an individual contribution of a single profile and a global contribution of all profiles into account. The associated uncertainties are propagated using the Monte Carlo method. Experimental study results indicate that the data fusion procedure improves the accuracy of available datasets. After fusion, all available data points are capable of being used in the form assessment.

  8. Electron Confinement in Cylindrical Potential Well

    NASA Astrophysics Data System (ADS)

    Baltenkov, A. S.; Msezane, A. Z.

    2016-05-01

    We show that studying the solutions of the wave equation for an electron confined in a cylindrical potential well offers the possibility to analyze the confinement behavior of an electron executing one- or two-dimensional motion in the remaining three-dimensional space within the framework of the same mathematical model of the potential well. Some low-lying electronic states with different symmetries are considered and the corresponding wave functions are calculated. The behavior of their nodes and their peak positions with respect to the parameters of the cylindrical well is analyzed. Additionally, the momentum distributions of electrons in these states are calculated. The limiting cases of the ratio of the cylinder length H to its radius R0 are considered; when H significantly exceeds R0 and when R0 is much greater than H. The possible application of the results obtained here for the description of the general features in the behavior of electrons in nanowires with metallic type of conductivity (or nanotubes) and ultrathin epitaxial films (or graphene sheets) are discussed. Possible experiments are suggested as well where the quantum confinement can be manifested. Work supported by the Uzbek Foundation (ASB) and by the U.S. DOE, Division of Chemical Sciences, Geosciences and Biosciences, Office of Basic Energy Sciences, Office of Energy Research (AZM).

  9. Statistics properties of a cylindrical vector partially coherent beam.

    PubMed

    Dong, Yiming; Cai, Yangjian; Zhao, Chengliang; Yao, Min

    2011-03-28

    Cylindrical vector partially coherent beam is introduced as a natural extension of cylindrical vector coherent beam based on the unified theory of coherence and polarization. Analytical propagation formula for the cross-spectral density matrix of a cylindrical vector partially coherent beam passing through paraxial ABCD optical system is derived based on the generalized Collins integral formula. As an application example, the statistics properties, such as the average intensity, spreading and the degree of polarization, of a cylindrical vector partially coherent beam propagating in free space are studied in detail. It is found that the statistics properties of a cylindrical vector partially coherent beam are much different from a cylindrical vector coherent beam. Our results may find applications in connection with laser beam shaping and optical trapping. PMID:21451623

  10. Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte

    SciTech Connect

    Wang, Yufeng; Zeng, Yongbin Qu, Ningsong; Zhu, Di

    2015-07-15

    An electrochemical etching process using a vibrating electrolyte of potassium hydroxide to prepare tungsten cylindrical nanotips is developed. The vibrating electrolyte eases the effects of a diffusion layer and extends the etching area, which aid in the production of cylindrical nanotips. Larger amplitudes and a vibration frequency of 35 Hz are recommended for producing cylindrical nanotips. Nanotips with a tip radius of approximately 43 nm and a conical angle of arctan 0.0216 are obtained.

  11. Static, cylindrically symmetric strings in general relativity with cosmological constant

    SciTech Connect

    Linet, B.

    1986-07-01

    The static, cylindrically symmetric solutions to Einstein's equations with a cosmological term describing cosmic strings are determined. The discussion depends on the sign of the cosmological constant.

  12. Preferences, needs and QALYs.

    PubMed Central

    Cohen, J

    1996-01-01

    Quality Adjusted Life Years (QALYs) have become a household word among health economists. Their use as a means of comparing the value of health programmes and medical interventions has stirred up controversy in the medical profession and the academic community. In this paper, I argue that QALY analysis does not adequately take into account the differentiated nature of the health state values it measures. Specifically, it does not distinguish between needs and preferences with respect to its valuation of health states. I defend the view that needs and preferences are clearly distinguishable, and that the concept of needs cannot be dispensed with, as many health economists suggest. It is argued that the scale along which health states are measured in QALY analysis is not a continuous interval scale, but one which concerns two distinctly different value dimensions. Measuring the values of health state intervals may reveal the weighting attached to the different value dimensions. PMID:8910777

  13. Son preference in Vietnam.

    PubMed

    Haughton, J; Haughton, D

    1995-01-01

    This article assesses the strength of son preference in Vietnam, as reflected in fertility behavior. It formulates and estimates a proportional hazards model applied to birth intervals, and a contraceptive prevalence model, using household survey data from 2,636 ever-married women aged 15-49 with at least one living child who were interviewed for the Vietnam Living Standards Survey 1992-1993. Son preference is found to be strong by world standards, but nevertheless, it has a minor effect on fertility; in its absence, the total fertility rate would fall by roughly 10 percent from the current level of about 3.2 children per woman of reproductive age. PMID:8826072

  14. Second-harmonic generation imaging of metal nano-objects with cylindrical vector beams.

    PubMed

    Bautista, Godofredo; Huttunen, Mikko J; Mäkitalo, Jouni; Kontio, Juha M; Simonen, Janne; Kauranen, Martti

    2012-06-13

    We introduce an imaging technique based on second-harmonic generation with cylindrical vector beams that is extremely sensitive to three-dimensional orientation and nanoscale morphology of metal nano-objects. Our experiments and second-harmonic field calculations based on frequency-domain boundary element method are in very good agreement. The technique provides contrast for structural features that cannot be resolved by linear techniques or conventional states of polarization and shows great potential for simple and cost-effective far-field optical imaging in plasmonics. PMID:22587307

  15. Coaching preferences of athletes.

    PubMed

    Terry, P C; Howe, B L

    1984-12-01

    The study examined the coaching preferences of 80 male and 80 female athletes, as measured by the Leadership Scale for Sports (Chelladurai and Saleh, 1978, 1980). In addition, it attempted to assess the applicability to sport of the Life-cycle and Path-goal theories of leadership. Comparisons between groups were made on the basis of sex, age, and type of sport. A MANOVA indicated that athletes in independent sports preferred more democratic behaviour (p less than .001) and less autocratic behaviour (p = .028) than athletes in interdependent sports. No differences in coaching preferences were found which could be attributed to the age or sex of the athlete, or the variability of the sports task. These results partially supported the Path-goal theory, but did not support the Life-cycle theory. Athletes of all groups tended to favour coaches who displayed training behaviour and rewarding behaviour "often", democratic behaviour and social support behaviour "occasionally", and autocratic behaviour "seldom". This consistency may be a useful finding for those organizations and institutions interested in preparing coaches. PMID:6525751

  16. Perspectives on Preference Aggregation.

    PubMed

    Regenwetter, Michel

    2009-07-01

    For centuries, the mathematical aggregation of preferences by groups, organizations, or society itself has received keen interdisciplinary attention. Extensive theoretical work in economics and political science throughout the second half of the 20th century has highlighted the idea that competing notions of rational social choice intrinsically contradict each other. This has led some researchers to consider coherent democratic decision making to be a mathematical impossibility. Recent empirical work in psychology qualifies that view. This nontechnical review sketches a quantitative research paradigm for the behavioral investigation of mathematical social choice rules on real ballots, experimental choices, or attitudinal survey data. The article poses a series of open questions. Some classical work sometimes makes assumptions about voter preferences that are descriptively invalid. Do such technical assumptions lead the theory astray? How can empirical work inform the formulation of meaningful theoretical primitives? Classical "impossibility results" leverage the fact that certain desirable mathematical properties logically cannot hold in all conceivable electorates. Do these properties nonetheless hold true in empirical distributions of preferences? Will future behavioral analyses continue to contradict the expectations of established theory? Under what conditions do competing consensus methods yield identical outcomes and why do they do so? PMID:26158988

  17. Clay Mineral Preferred Orientation

    NASA Astrophysics Data System (ADS)

    Day-Stirrat, R. J.

    2014-12-01

    Anisotropy of the orientation of clay minerals, often referred to as texture, may be unique to sediments' deposition, composition, deformation or diagenetic history. The literature is rich with studies that include preferred orientation generation in fault gouge, low-grade metamorphic rocks, sediments with variable clay content and during the smectite-to-illite transformation. Untangling the interplay between many competing factors in any one geologic situation has proven a significant challenge over many years. Understanding how, where and when clay minerals develop a preferred orientation has significant implications for permeability anisotropy in shallow burial, the way mechanical properties are projected from shallower to deeper settings in basin modeling packages and the way velocity anisotropy is accounted for in seismic data processing. The assessment of the anisotropic properties of fine-grained siliciclastic rocks is gaining significant momentum in rock physics research. Therefore, a fundamental understanding of how clay minerals develop a preferred orientation in space and time is crucial to the understanding of anisotropy of physical properties. The current study brings together a wealth of data that may be used in a predictive sense to account for fabric anisotropy that may impact any number of rock properties.

  18. Electrochemical cell having cylindrical electrode elements

    DOEpatents

    Nelson, Paul A.; Shimotake, Hiroshi

    1982-01-01

    A secondary, high temperature electrochemical cell especially adapted for lithium alloy negative electrodes, transition metal chalcogenide positive electrodes and alkali metal halide or alkaline earth metal halide electrolyte is disclosed. The cell is held within an elongated cylindrical container in which one of the active materials is filled around the outside surfaces of a plurality of perforate tubular current collectors along the length of the container. Each of the current collector tubes contain a concentric tubular layer of electrically insulative ceramic as an interelectrode separator. The active material of opposite polarity in elongated pin shape is positioned longitudinally within the separator layer. A second electrically conductive tube with perforate walls can be swagged or otherwise bonded to the outer surface of the pin as a current collector and the electrically insulative ceramic layer can be coated or otherwise layered onto the outer surface of this second current collector. Alternatively, the central pin electrode can include an axial core as a current collector.

  19. Premixed flames in closed cylindrical tubes

    NASA Astrophysics Data System (ADS)

    Metzener, Philippe; Matalon, Moshe

    2001-09-01

    We consider the propagation of a premixed flame, as a two-dimensional sheet separating unburned gas from burned products, in a closed cylindrical tube. A nonlinear evolution equation, that describes the motion of the flame front as a function of its mean position, is derived. The equation contains a destabilizing term that results from the gas motion induced by thermal expansion and has a memory term associated with vorticity generation. Numerical solutions of this equation indicate that, when diffusion is stabilizing, the flame evolves into a non-planar form whose shape, and its associated symmetry properties, are determined by the Markstein parameter, and by the initial data. In particular, we observe the development of convex axisymmetric or non-axisymmetric flames, tulip flames and cellular flames.

  20. Naked singularity resolution in cylindrical collapse

    SciTech Connect

    Kurita, Yasunari; Nakao, Ken-ichi

    2006-03-15

    In this paper, we study the gravitational collapse of null dust in cylindrically symmetric spacetime. The naked singularity necessarily forms at the symmetry axis. We consider the situation in which null dust is emitted again from the naked singularity formed by the collapsed null dust and investigate the backreaction by this emission for the naked singularity. We show a very peculiar but physically important case in which the same amount of null dust as that of the collapsed one is emitted from the naked singularity as soon as the ingoing null dust hits the symmetry axis and forms the naked singularity. In this case, although this naked singularity satisfies the strong curvature condition by Krolak (limiting focusing condition), geodesics which hit the singularity can be extended uniquely across the singularity. Therefore, we may say that the collapsing null dust passes through the singularity formed by itself and then leaves for infinity. Finally, the singularity completely disappears and the flat spacetime remains.

  1. Cylindrical spreading due to downwind refraction.

    PubMed

    Makarewicz, Rufin

    2016-04-01

    Downwind propagation is analyzed for a low level jet (LLJ). The LLJ is characterized by a wind speed maximum (at least 10-20 m/s with peak speeds up to 30 m/s) a few hundred meters above the ground. Close to an elevated point source, such as a wind turbine or an aircraft, spherical spreading results in a 6 dB decrease in sound level per doubling of the distance. Wind turbine noise measurements show that at a transition distance, the downwind propagation changes the spherical spreading into a cylindrical spreading with a 3 dB decrease. It is shown how the transition distance and sound intensity depend on the LLJ parameters. The pivotal phenomenon is the non-coherent superposition of ground reflected rays in the turbulent atmosphere. PMID:27106309

  2. Dispersive cylindrical cloaks under nonmonochromatic illumination

    NASA Astrophysics Data System (ADS)

    Argyropoulos, Christos; Kallos, Efthymios; Hao, Yang

    2010-01-01

    Transformation-based cylindrical cloaks and concentrators are illuminated with nonmonochromatic waves and unusual effects are observed with interesting potential applications. The transient responses of the devices are studied numerically with the finite-difference time-domain method and the results are verified with analytical formulas. We compute the effective bandwidth of several cloaking schemes as well as the effect of losses on the performance of the structures. We also find that narrowband behavior, frequency shift effects, time delays, and spatial disturbances of the incoming waves are dominant due to the inherently dispersive nature of the devices. These effects are important and should be taken into account when designing metamaterial-based devices.

  3. Cathode Effects in Cylindrical Hall Thrusters

    SciTech Connect

    Granstedt, E.M.; Raitses, Y.; Fisch, N. J.

    2008-09-12

    Stable operation of a cylindrical Hall thruster (CHT) has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode-neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.

  4. Cathode effects in cylindrical Hall thrusters

    SciTech Connect

    Granstedt, E. M.; Raitses, Y.; Fisch, N. J.

    2008-11-15

    Stable operation of a cylindrical Hall thruster has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.

  5. Plasmonic oligomers in cylindrical vector light beams

    PubMed Central

    Hentschel, Mario; Dorfmüller, Jens; Jäger, Sebastian; Kern, Andreas M; Braun, Kai; Zhang, Dai; Meixner, Alfred J

    2013-01-01

    Summary We investigate the excitation as well as propagation of magnetic modes in plasmonic nanostructures. Such structures are particularly suited for excitation with cylindrical vector beams. We study magneto-inductive coupling between adjacent nanostructures. We utilize high-resolution lithographic techniques for the preparation of complex nanostructures consisting of gold as well as aluminium. These structures are subsequently characterized by linear optical spectroscopy. The well characterized and designed structures are afterwards studied in depth by exciting them with radial and azimuthally polarized light and simultaneously measuring their plasmonic near-field behavior. Additionally, we attempt to model and simulate our results, a project which has, to the best of our knowledge, not been attempted so far. PMID:23400561

  6. Method for making generally cylindrical underground openings

    DOEpatents

    Routh, J.W.

    1983-05-26

    A rapid, economical and safe method for making a generally cylindrical underground opening such as a shaft or a tunnel is described. A borehole is formed along the approximate center line of where it is desired to make the underground opening. The borehole is loaded with an explodable material and the explodable material is detonated. An enlarged cavity is formed by the explosive action of the detonated explodable material forcing outward and compacting the original walls of the borehole. The enlarged cavity may be increased in size by loading it with a second explodable material, and detonating the second explodable material. The process may be repeated as required until the desired underground opening is made. The explodable material used in the method may be free-flowing, and it may be contained in a pipe.

  7. Ion orbits in a cylindrical Langmuir probe

    SciTech Connect

    Taccogna, Francesco; Longo, Savino; Capitelli, Mario

    2006-04-15

    It has been suggested that in weakly collisional sheaths, potential wells and barriers could appear due to ion-neutral momentum and charge transfer collisions. These can cause the presence of repulsed and trapped ions in the region surrounding a negatively biased Langmuir probe, invalidating the commonly used orbital-motion-limited theory of ion current. This is still an open question concerning also the charging and shielding of dust grains, and at present, no fully self-consistent treatment exists. For this reason, a particle-in-cell/test-particle Monte Carlo simulation of the dynamics of an argon plasma in the region surrounding an attracting cylindrical probe at medium gas pressure has been developed. The results of the present simulation for different probe potentials and discharge pressures demonstrate the complex structure of electric potential around the probe and the failure of collisionless theories.

  8. Potential flow inside an evaporating cylindrical line.

    PubMed

    Petsi, A J; Burganos, V N

    2005-10-01

    An analytical solution to the problem of potential flow inside an evaporating line is obtained. The line is shaped as a half-cylinder lying on a substrate, and evaporates with either pinned or depinned contact lines. The solution is provided through the technique of separation of variables in the velocity potential and stream function formulations. Based on the flow field calculations, it is estimated that the coffee-stain phenomenon should be expected even for uniform evaporation flux throughout the cylindrical surface, provided that the contact lines remain anchored. A simple expression for the velocity potential is also suggested, which reproduces the local velocity vector with excellent accuracy. The vertically averaged velocity is calculated also for other contact line values, revealing for any value an outward liquid flow for pinned lines as opposed to inward flow for depinned lines. PMID:16383581

  9. SPSM and its application in cylindrical shells

    NASA Astrophysics Data System (ADS)

    Nie, Wu; Zhou, Su-Lian; Peng, Hui

    2008-03-01

    In naval architectures, the structure of prismatic shell is used widely. But there is no suitable method to analyze this kind of structure. Stiffened prismatic shell method (SPSM) presented in this paper, is one of the harmonic semi-analytic methods. Theoretically, strong stiffened structure can be analyzed economically and accurately. SPSM is based on the analytical solution of the governing differential equations for orthotropic cylindrical shells. In these differential equations, the torsional stiffness, bending stiffness and the exact position of each stiffener are taken into account with the Heaviside singular function. An algorithm is introduced, in which the actions of stiffeners on shells are replaced by external loads at each stiffener position. Stiffened shells can be computed as non-stiffened shells. Eventually, the displacement solution of the equations is acquired by the introduction of Green function. The stresses in a corrugated transverse bulkhead without pier base of an oil tanker are computed by using SPSM.

  10. Concentration profiles in drying cylindrical filaments

    NASA Astrophysics Data System (ADS)

    Czaputa, Klaus; Brenn, Günter; Meile, Walter

    2008-12-01

    We analyze theoretically the drying of cylindrical filaments. For modelling the mass transfer on the gas side of the liquid-gas interface of the shrinking circular cylindrical filament, we apply the model of Abramzon and Sirignano, which was originally developed for spherical geometry. As a consequence of mass transfer at constant Sherwood number, we obtain a d2-law for the shrinkage of the cylinder as in the case of the spherical geometry, which expresses that the cross-sectional area of the cylinder shrinks at a constant rate with time. For this situation, the diffusion equation for the liquid phase mixture components becomes separable upon transformation into similarity coordinates and is solved analytically to obtain the concentration profiles inside the filament as functions of time. The dependency of the profiles on the radial coordinate is determined by a series of Kummer’s functions. Applying this result, we study the evolution of the concentration profiles in the liquid phase with time as dependent on a parameter given as the ratio of rate of shrinkage of the cross-sectional area of the cylinder to liquid-phase diffusion coefficient, which was identified as relevant for the shape of the concentration profiles formed in the liquid during the drying process. As an example, we present computed results for the constant evaporation rate regime in the dry-spinning process of a polyvinyl-alcohol (PVA)-water system. Comparison of our analytical results with full numerical solutions of the diffusion equation from the literature, achieved with concentration-dependent diffusion coefficient, reveals very good agreement.

  11. Folding to Curved Surfaces: A Generalized Design Method and Mechanics of Origami-based Cylindrical Structures.

    PubMed

    Wang, Fei; Gong, Haoran; Chen, Xi; Chen, C Q

    2016-01-01

    Origami structures enrich the field of mechanical metamaterials with the ability to convert morphologically and systematically between two-dimensional (2D) thin sheets and three-dimensional (3D) spatial structures. In this study, an in-plane design method is proposed to approximate curved surfaces of interest with generalized Miura-ori units. Using this method, two combination types of crease lines are unified in one reprogrammable procedure, generating multiple types of cylindrical structures. Structural completeness conditions of the finite-thickness counterparts to the two types are also proposed. As an example of the design method, the kinematics and elastic properties of an origami-based circular cylindrical shell are analysed. The concept of Poisson's ratio is extended to the cylindrical structures, demonstrating their auxetic property. An analytical model of rigid plates linked by elastic hinges, consistent with numerical simulations, is employed to describe the mechanical response of the structures. Under particular load patterns, the circular shells display novel mechanical behaviour such as snap-through and limiting folding positions. By analysing the geometry and mechanics of the origami structures, we extend the design space of mechanical metamaterials and provide a basis for their practical applications in science and engineering. PMID:27624892

  12. Development of the Cylindrical Wire Electrical Discharge Machining Process.

    SciTech Connect

    McSpadden, SB

    2002-01-22

    Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. A precise, flexible, and corrosion-resistant underwater rotary spindle was designed and added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometries. A detailed spindle error analysis identifies the major source of error at different frequency. The mathematical model for the material removal of cylindrical wire EDM process is derived. Experiments were conducted to explore the maximum material removal rate for cylindrical and 2D wire EDM of carbide and brass work-materials. Compared to the 2D wire EDM, higher maximum material removal rates may be achieved in the cylindrical wire EDM. This study also investigates the surface integrity and roundness of parts created by the cylindrical wire EDM process. For carbide parts, an arithmetic average surface roughness and roundness as low as 0.68 and 1.7 {micro}m, respectively, can be achieved. Surfaces of the cylindrical EDM parts were examined using Scanning Electron Microscopy (SEM) to identify the craters, sub-surface recast layers and heat-affected zones under various process parameters. This study has demonstrated that the cylindrical wire EDM process parameters can be adjusted to achieve either high material removal rate or good surface integrity.

  13. Technical Note: Experimental determination of the effective point of measurement of two cylindrical ionization chambers in a clinical proton beam

    SciTech Connect

    Sugama, Yuya; Nishio, Teiji; Onishi, Hiroshi

    2015-07-15

    Purpose: IAEA TRS-398 notes that cylindrical ionization chambers are preferred for reference proton dosimetry. If a cylindrical ionization chamber is used in a phantom to measure the dose as a function of depth, the effective point of measurement (EPOM) must be taken into account. IAEA TRS-398 recommends a displacement of 0.75 times the inner cavity radius (0.75R) for heavy ion beams. Theoretical models by Palmans and by Bhullar and Watchman confirmed this value. However, the experimental results vary from author to author. The purpose of this study is to accurately measure the displacement and explain the past experimental discrepancies. Methods: In this work, we measured the EPOM of cylindrical ionization chambers with high accuracy by comparing the Bragg-peak position obtained with cylindrical ionization chambers (PTW 30013, PTW 31016) to that obtained using a plane-parallel ionization chamber (PTW 34045). Results: The EPOMs of PTW 30013 and 31016 were shifted by 0.92 ± 0.07 R with R = 3.05 mm and 0.90 ± 0.14 R with R = 1.45 mm, respectively, from the reference point toward the source. Conclusions: The EPOMs obtained were greater than the value of 0.75R proposed by the IAEA TRS-398 and the analytical results.

  14. Shifting Preferences in Pornography Consumption.

    ERIC Educational Resources Information Center

    Zillmann, Dolf; Bryant, Jennings

    1986-01-01

    Concludes that subjects with considerable prior exposure to common, nonviolent pornography preferred to watch uncommon pornography. Male nonstudents preferred it almost exclusively, as did male students to a lesser extent. Females also exhibited this consumption preference, though it was far less pronounced, especially in female students. (JD)

  15. Micelle Morphology and Mechanical Response of Triblock Gels

    SciTech Connect

    Seitz, Michelle E.; Burghardt, Wesley R.; Shull, Kenneth R.

    2010-01-12

    The effect of polymer concentration on mechanical response and micelle morphology of ABA and AB copolymers in B-selective solvents has been systematically studied. Micelle morphology was determined using a combination of small-angle X-ray scattering, shear, and birefringence while mechanical response at low and high strains was determined using indentation techniques. Self-consistent field theory calculations were used to determine micelle volume fraction profiles and to construct an equilibrium phase map. The transition from spherical to cylindrical micelles increases the triblock gel modulus and energy dissipation. Combining knowledge of gel relaxation time, which determines the rate at which the gel can equilibrate its micelle structure, with the equilibrium phase map allows estimation of the experimental temperatures and time scales over which kinetic trapping will arrest micelle structure evolution. Kinetic trapping enables cylindrical morphologies to be obtained at significantly lower polymer fractions than is possible in equilibrated systems.

  16. Cylindrical Implosion Experiments using Laser Direct Drive

    NASA Astrophysics Data System (ADS)

    Tubbs, David

    1998-11-01

    Development of high-gain targets for the National Ignition Facility relies considerably on computational modeling, and it is important that our codes are validated against relevant experimental data in convergent geometry.(W. J. Krauser et al., Phys. Plasmas 3, 2084 (1996); D. C. Wilson et al., Phys. Plasmas 5, 1953 (1998)) In collaboration with the University of Rochester, we have begun a campaign of hydrodynamic instability experiments in cylindrical geometry using direct drive,(D. L. Tubbs et al., submitted to Laser and Particle Beams (1998); C. W. Barnes et al., submitted to Rev. Sci. Instrm. (1998)) building on our success in indirect drive.( W. W. Hsing et al., Phys. Plasmas 5, 1832 (1997); W. W. Hsing and N. M. Hoffman, Phys. Rev. Lett., 3876 (1997)) Cylindrical targets facilitate direct diagnostic access to the convergent, hydrodynamic flow. The energy advantage of direct drive and its excellent target-illumination symmetry (achieved at OMEGA through use of Distributed Phase Plates and SSD) permit more energetic implosions, larger target scale (hence greater diagnostic resolution), longer acceleration timescales, and higher convergence than were possible using indirect drive. We estimate that specific laser energy delivered to the target for direct drive at OMEGA is roughly 4 times that achieved for indirect drive at Nova. Our first experiments (January 1998) yield excellent data for the first highly symmetrical direct-drive implosions, with which we benchmark zeroth-order hydrodynamic simulations. Two-dimensional (2-D) LASNEX calculations, using as-shot laser power histories and no further physics adjustments, match measured target-implosion data within theoretical and experimental errors. In addition, 2-D LASNEX simulations of single-mode (m=28, azimuthally symmetric) perturbation growth agree well with data obtained during our first week of experiments. For 1.5-micron initial perturbation amplitude, we observe Rayleigh-Taylor growth factors of order 10

  17. Converging cylindrical shocks in ideal magnetohydrodynamics

    SciTech Connect

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-09-15

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ{sub 0}/p{sub 0}) I/(2 π) where I is the current, μ{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The

  18. Converging cylindrical shocks in ideal magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-09-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=sqrt{μ _0/p_0} I/(2 π ) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field

  19. Patient Preferences for OCD treatment

    PubMed Central

    Patel, Sapana R.; Simpson, Helen Blair

    2011-01-01

    Objective To explore preferences for the treatment of obsessive compulsive disorder (OCD). We hypothesized that OCD patients will select a combination of medication and psychotherapy as their most preferred choice overall. Methods The authors designed a treatment preference survey using two health economics methods, forced choice and contingent ranking methods, to elicit preferences for OCD treatment available in mainstream care (Serotonin Reuptake Inhibitors [SRIs]), Exposure and Ritual Prevention [EX/RP], and their combination), and for novel treatments under development at OCD research clinics. This survey was given by telephone to 89 individuals with OCD who called the OCD research clinic at the New York State Psychiatric Institute between July 2008 and January 2009. Results Most participants chose combination treatment (43%) or EX/RP (42%) over SRI medication (16%). Participants ranked investigational psychotherapy as their most preferred novel treatment (endorsed by 48% of participants) and deep brain stimulation as their least preferred novel treatment (endorsed by 77% of participants). Qualitative data suggest that prior treatment experience, concerns about medications, and logistical and practical concerns about treatment regimens affect preferences. Conclusions Patients with OCD have identifiable treatment preferences. In this sample of convenience, most preferred either combination treatment or psychotherapy. Future studies should investigate prospectively what modifies these preferences and how these preferences affect treatment outcome. PMID:21114948

  20. Combining symmetry-separated and bent-bond spin-coupled models of cylindrically symmetric multiple bonding

    NASA Astrophysics Data System (ADS)

    Penotti, Fabio E.; Cooper, David L.

    2015-07-01

    We examine the symmetry properties of spin-coupled (or full generalised valence bond) wavefunctions for C2H2 and N2. The symmetry-separated (σ,π) and bent-bond (ω) solutions are totally symmetric only in the D4h and D3h subgroups of D∞h, respectively. Two fairly different strategies are explored for imposing full cylindrical symmetry, with one of them (small nonorthogonal configuration interaction calculations involving rotated versions of the wavefunction) turning out to be somewhat preferable on energetic grounds to the other one (application of additional spin constraints to a single spatial configuration). It is also shown that mixing together the cylindrically symmetric symmetry-separated and bent-bond spin-coupled models leads to relatively small energy improvements unless the valence orbitals in each type of configuration are reoptimised.

  1. Rotating cylindrical wormholes and energy conditions

    NASA Astrophysics Data System (ADS)

    Bronnikov, K. A.; Krechet, V. G.

    2016-01-01

    We seek wormholes among rotating cylindrically symmetric configurations in general relativity. Exact wormhole solutions are presented with such sources of gravity as a massless scalar field, a cosmological constant, and a scalar field with an exponential potential. However, none of these solutions are asymptotically flat, which excludes the existence of wormhole entrances as local objects in our Universe. To overcome this difficulty, we try to build configurations with flat asymptotic regions using the cut-and-paste procedure: on both sides of the throat, a wormhole solution is matched to a properly chosen region of flat space-time at some surfaces Σ- and Σ+. It is shown, however, that if the source of gravity in the throat region is a scalar field with an arbitrary potential, then one or both thin shells appearing on Σ- and Σ+ inevitably violate the null energy condition. Thus, although rotating wormhole solutions are easily found without exotic matter, such matter is still necessary for obtaining asymptotic flatness.

  2. Jet mixing in a reacting cylindrical crossflow

    NASA Technical Reports Server (NTRS)

    Leong, M. Y.; Samuelsen, G. S.; Holdeman, J. D.

    1995-01-01

    This paper addresses the mixing of air jets into the hot, fuel-rich products of a gas turbine primary zone. The mixing, as a result, occurs in a reacting environment with chemical conversion and substantial heat release. The geometry is a crossflow confined in a cylindrical duct with side-wall injection of jets issuing from round orifices. A specially designed reactor, operating on propane, presents a uniform mixture without swirl to mixing modules consisting of 8, 9, 10, and 12 holes at a momentum-flux ratio of 57 and a jet-to-mainstream mass-flow ratio of 2.5. Concentrations of O2, CO2, CO, and HC are obtained upstream, downstream, and within the orifice plane. O2 profiles indicate jet penetration while CO2, CO, and HC profiles depict the extent of reaction. Jet penetration is observed to be a function of the number of orifices and is found to affect the mixing in the reacting system. The results demonstrate that one module (the 12-hole) produces near-optimal penetration defined here as a jet penetration closest to the module half-radius, and hence the best uniform mixture at a plane one duct radius from the orifice leading edge.

  3. Capillary effects on floating cylindrical particles

    NASA Astrophysics Data System (ADS)

    Dixit, Harish N.; Homsy, G. M.

    2012-12-01

    In this study, we develop a systematic perturbation procedure in the small parameter, B1/2, where B is the Bond number, to study capillary effects on small cylindrical particles at interfaces. Such a framework allows us to address many problems involving particles on flat and curved interfaces. In particular, we address four specific problems: (i) capillary attraction between cylinders on flat interface, in which we recover the classical approximate result of Nicolson ["The interaction between floating particles," Proc. Cambridge Philos. Soc. 45, 288-295 (1949), 10.1017/S0305004100024841], thus putting it on a rational basis; (ii) capillary attraction and aggregation for an infinite array of cylinders arranged on a periodic lattice, where we show that the resulting Gibbs elasticity obtained for an array can be significantly larger than the two cylinder case; (iii) capillary force on a cylinder floating on an arbitrary curved interface, where we show that in the absence of gravity, the cylinder experiences a lateral force which is proportional to the gradient of curvature; and (iv) capillary attraction between two cylinders floating on an arbitrary curved interface. The present perturbation procedure does not require any restrictions on the nature of curvature of the background interface and can be extended to other geometries.

  4. Buckling analysis of cylindrical shells with cracks

    SciTech Connect

    Limam, A.; Jullien, J.F.; Ouayou, B.S.

    1995-12-31

    In many areas of aeronautical nuclear and civil engineering practice, large thin-walled structural panels are increasingly becoming characteristic architectural features. Indeed, nuclear reactor vessels and cryogenic tanks of a launcher, for instance, are made up of several thin-walled panels welded together. Instability and buckling phenomenon present over-riding constraints on the design process. In addition, the presence of joints which are very often the origin of surface fissures poses increasing dangers on the overall stability of these structures. This research deals with the analysis of the effects of cracks on the behavior of cylindrical shells subject to external pressure. The study was divided into two major parts. In the first part, experiments were carried out with shells without cracks, in order to obtain reference data. A numerical study of various models explains the experimental results and shows the combined effect of the geometric imperfections and boundary conditions on the critical load. The second part focused on several experimental tests and numerical simulations on shells with in- depth fissures as a function of their population, orientation, length and position with respect to the welds or joints. The agreement between numerical and experimental results confirms the new possibility to design with the aid of the finite element program under the condition that the calculations are carried out by means of an appropriate numerical method.

  5. Technology Selections for Cylindrical Compact Fabrication

    SciTech Connect

    Jeffrey A. Phillips

    2010-10-01

    A variety of process approaches are available and have been used historically for manufacture of cylindrical fuel compacts. The jet milling, fluid bed overcoating, and hot press compacting approach being adopted in the U.S. AGR Fuel Development Program for scale-up of the compacting process involves significant paradigm shifts from historical approaches. New methods are being pursued because of distinct advantages in simplicity, yield, and elimination of process mixed waste. Recent advances in jet milling technology allow simplified dry matrix powder preparation. The matrix preparation method is well matched with patented fluid bed powder overcoating technology recently developed for the pharmaceutical industry and directly usable for high density fuel particle matrix overcoating. High density overcoating places fuel particles as close as possible to their final position in the compact and is matched with hot press compacting which fully fluidizes matrix resin to achieve die fill at low compacting pressures and without matrix end caps. Overall the revised methodology provides a simpler process that should provide very high yields, improve homogeneity, further reduce defect fractions, eliminate intermediate grading and QC steps, and allow further increases in fuel packing fractions.

  6. Force balances in systems of cylindrical polyelectrolytes.

    PubMed

    Brenner, S L; McQuarrie, D A

    1973-04-01

    A detailed analysis is made of the model system of two parallel cylindrical polyelectrolytes which contain ionizable groups on their surfaces and are immersed in an ionic bathing medium. The interaction between the cylinders is examined by considering the interplay between repulsive electrostatic forces and attractive forces of electrodynamic origin. The repulsive force arises from the screened coulomb interaction between the surface charge distributions on the cylinders and has been treated by developing a solution to the linearized Poisson-Boltzmann equation. The boundary condition at the cylinder surfaces is determined as a self-consistent functional of the potential, with the input consisting of the density of ionizable groups and their dissociation constants. It is suggested that a reasonably accurate representation for the form of the attractive force can be obtained by performing a pairwise summation of the individual interatomic forces. A quantitative estimate is obtained using a Hamaker constant chosen on the basis of rigorous calculations on simpler systems. It is found that a balance exists between these repulsive and attractive forces at separations in good agreement with those observed in arrays of tobacco mosaic virus and in the A band myosin lattice in striated muscle. The behavior of the balance point as a function of the pH and ionic strength of the bathing medium closely parallels that seen experimentally. PMID:4696760

  7. Cylindrical converging shock initiation of reactive materials

    NASA Astrophysics Data System (ADS)

    Jenkins, Charles M.; Horie, Yasuyuki; Lindsay, Christopher Michael; Butler, George C.; Lambert, David; Welle, Eric

    2012-03-01

    Recent research has been conducted that builds on the Forbes et al. (1997) study of inducing a rapid solid state reaction in a highly porous core using a converging cylindrical shock driven by a high explosive. The high explosive annular charge used in this research to compress the center reactive core was comparable to PBXN-110. Some modifications were made on the physical configuration of the test item for scale-up and ease of production. The reactive materials (I2O5/Al and I2O5/Al/Teflon) were hand mixed and packed to a tap density of about 32 percent. Data provided by a Cordon 114 high speed framing camera and a Photon Doppler Velocimetry instrument provided exit gas expansion, core particle and cylinder wall velocities. Analysis indicates that the case expansion velocity differs according to the core formulation and behaved similar to the baseline high explosive core with the exit gas of the reactive materials producing comparable velocities. Results from CTH hydrocode used to model the test item compares favorably to the experimental results.

  8. Cylindrical optic figuring dwell time optimization

    NASA Astrophysics Data System (ADS)

    Waluschka, Eugene

    2000-11-01

    The Constellation-X, grazing incidence, x-ray telescope may be fabricated from replicated segments. A series of mandrels will serve as the 'masters' in the replication processes. Diamond turning (milling) followed by abrasive figuring followed by a super polishing are the steps currently envisioned in making just one (of many) mandrel. The abrasive figuring of a mandrel is accomplished by moving a grinding tool along a helical path on this almost cylindrical surface. The measurement of the surface is, however, performed along 'axial' scan lines which intercept this helical path. This approach to figuring and measuring permits a relatively simple scheme to be implemented for the determination of the optimal dwell times of the figuring tool. These optimal dwell times are determined by a deconvolution which approaches the problem in a linear programming context and uses the Simplex Method. The approach maximizes the amount of material removed at any point subject to inequality constraints. The effects of using these 'optimum' dwell times is to significantly improve the tools effectiveness at removing the higher spatial frequencies while staying (strictly) within the bounds and constraints imposed by the hardware. In addition, the ringing at the edges of the optic, frequently present in deconvolution problems, is completely eliminated.

  9. Cylindrical Hall Thrusters with Permanent Magnets

    SciTech Connect

    Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.

    2010-10-18

    The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT. __________________________________________________

  10. Surface tension and long range corrections of cylindrical interfaces

    SciTech Connect

    Bourasseau, E.; Ghoufi, A.

    2015-12-21

    The calculation of the surface tension of curved interfaces has been deeply investigated from molecular simulation during this last past decade. Recently, the thermodynamic Test-Area (TA) approach has been extended to the calculation of surface tension of curved interfaces. In the case of the cylindrical vapour-liquid interfaces of water and Lennard-Jones fluids, it was shown that the surface tension was independent of the curvature of the interface. In addition, the surface tension of the cylindrical interface is higher than that of the planar interface. Molecular simulations of cylindrical interfaces have been so far performed (i) by using a shifted potential, (ii) by means of large cutoff without periodic boundary conditions, or (iii) by ignoring the long range corrections to the surface tension due to the difficulty to estimate them. Indeed, unlike the planar interfaces there are no available operational expressions to consider the tail corrections to the surface tension of cylindrical interfaces. We propose here to develop the long range corrections of the surface tension for cylindrical interfaces by using the non-exponential TA (TA2) method. We also extend the formulation of the Mecke-Winkelmann corrections initially developed for planar surfaces to cylindrical interfaces. We complete this study by the calculation of the surface tension of cylindrical surfaces of liquid tin and copper using the embedded atom model potentials.

  11. Limit of concentration for cylindrical concentrators under extended light sources.

    PubMed

    Miñano, J C; Luque, A

    1983-08-15

    Cylindrical concentrators illuminated by an extended source with an arbitrary distribution of radiance are analyzed taking into account basic properties derived from the Fermat principle and not from the specific concentrator shape. The upper limit of concentration achievable with this type of concentrator is obtained and it is found to be lower than that of general (3-D) concentrators. Cylindrical compound parabolic concentrators are analyzed in the light of this theory, and it is shown that they achieve the highest optical concentration possible for a cylindrical concentrator. PMID:18196152

  12. Mice overexpressing CD97 in intestinal epithelial cells provide a unique model for mammalian postnatal intestinal cylindrical growth.

    PubMed

    Aust, Gabriela; Kerner, Christiane; Gonsior, Susann; Sittig, Doreen; Schneider, Hartmut; Buske, Peter; Scholz, Markus; Dietrich, Norman; Oldenburg, Sindy; Karpus, Olga N; Galle, Jörg; Amasheh, Salah; Hamann, Jörg

    2013-07-01

    Postnatal enlargement of the mammalian intestine comprises cylindrical and luminal growth, associated with crypt fission and crypt/villus hyperplasia, respectively, which subsequently predominate before and after weaning. The bipartite adhesion G protein-coupled receptor CD97 shows an expression gradient along the crypt-villus axis in the normal human intestine. We here report that transgenic mice overexpressing CD97 in intestinal epithelial cells develop an upper megaintestine. Intestinal enlargement involves an increase in length and diameter but does not affect microscopic morphology, as typical for cylindrical growth. The megaintestine is acquired after birth and before weaning, independent of the genotype of the mother, excluding altered availability of milk constituents as driving factor. CD97 overexpression does not regulate intestinal growth factors, stem cell markers, and Wnt signaling, which contribute to epithelial differentiation and renewal, nor does it affect suckling-to-weaning transition. Consistent with augmented cylindrical growth, suckling but not adult transgenic mice show enlarged crypts and thus more crypt fissions caused by a transient increase of the crypt transit-amplifying zone. Intestinal enlargement by CD97 requires its seven-span transmembrane/cytoplasmic C-terminal fragment but not the N-terminal fragment binding partner CD55. In summary, ectopic expression of CD97 in intestinal epithelial cells provides a unique model for intestinal cylindrical growth occurring in breast-fed infants. PMID:23676664

  13. Velocity Inversion In Cylindrical Couette Gas Flows

    NASA Astrophysics Data System (ADS)

    Dongari, Nishanth; Barber, Robert W.; Emerson, David R.; Zhang, Yonghao; Reese, Jason M.

    2012-05-01

    We investigate a power-law probability distribution function to describe the mean free path of rarefied gas molecules in non-planar geometries. A new curvature-dependent model is derived by taking into account the boundary-limiting effects on the molecular mean free path for surfaces with both convex and concave curvatures. In comparison to a planar wall, we find that the mean free path for a convex surface is higher at the wall and exhibits a sharper gradient within the Knudsen layer. In contrast, a concave wall exhibits a lower mean free path near the surface and the gradients in the Knudsen layer are shallower. The Navier-Stokes constitutive relations and velocity-slip boundary conditions are modified based on a power-law scaling to describe the mean free path, in accordance with the kinetic theory of gases, i.e. transport properties can be described in terms of the mean free path. Velocity profiles for isothermal cylindrical Couette flow are obtained using the power-law model. We demonstrate that our model is more accurate than the classical slip solution, especially in the transition regime, and we are able to capture important non-linear trends associated with the non-equilibrium physics of the Knudsen layer. In addition, we establish a new criterion for the critical accommodation coefficient that leads to the non-intuitive phenomena of velocity-inversion. Our results are compared with conventional hydrodynamic models and direct simulation Monte Carlo data. The power-law model predicts that the critical accommodation coefficient is significantly lower than that calculated using the classical slip solution and is in good agreement with available DSMC data. Our proposed constitutive scaling for non-planar surfaces is based on simple physical arguments and can be readily implemented in conventional fluid dynamics codes for arbitrary geometric configurations.

  14. Investigation of HE driven cylindrical liner

    SciTech Connect

    Tan, Tai-Ho

    1995-03-01

    We developed a technique that can compress most materials to densities much higher than their original values and shock them hard enough to undergo phase changes to various partially ionized states. The process involves using high explosives to drive a thin cylindrical liner so that it will progressively implode and converge along the axis at very high velocity. The device is simple yet versatile. Its configuration is ideally suited as a compact laboratory for the investigation of the behavior of dense media under extreme conditions. Code simulations show that liners made from most metals can be successfully imploded to converge on axis, producing over 10 MB pressure. For example, a 2D hydrocode calculation predicts that in a simple configuration where a hollow core PBX-9501 explosive cylinder is corner initiated to drive a thin seamless 304 SS tubing, the final convergence velocity can exceed 1 cm/[Ls to produce a 15 MB pressure at impact as the density increases to 19.5 g/cc. The temperature from shock heating rises rapidly above 8 eV, and the result is a combination of radiation and plasma emissions. We have carried out several experiments with a wide array of diagnostics to investigate the implosion dynamics and final state interaction phenomena, and the results are compared with the code predictions. Radiographs of the liner implosion strongly indicate that the hydrodynamic processes are well behaved and calculable. Temperature measurement from the optical radiation is generally consistent with the code prediction. The velocity of the plasma front is measured by using optical pins and fast framing photography, and is found to lie between 11--17 cm/{mu}s. Fast framing photographs were taken with the aid of self luminous light to observe the evacuated chamber inside the imploding liner. The experimental results and their comparison with the calculation are discussed.

  15. 108. Cylindrical chamber where gas exits stove to below ground ...

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

    108. Cylindrical chamber where gas exits stove to below ground flue that leads to stack. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

  16. Drag coefficient and settling velocity for particles of cylindrical shape

    SciTech Connect

    Gabitto, Jorge; Tsouris, Costas

    2008-01-01

    Solid particles of cylindrical shape play a significant role in many separations processes. Explicit equations for the drag coefficient and the terminal velocity of free-falling cylindrical particles have been developed in this work. The developed equations are based on available experimental data for falling cylindrical particles in all flow regimes. The aspect ratio (i.e., length-over-diameter ratio) has been used to account for the particle shape. Comparisons with correlations proposed by other researchers using different parameters to account for the geometry are presented. Good agreement is found for small aspect ratios, and increasing differences appear when the aspect ratio increases. The aspect ratio of cylindrical particles satisfactorily accounts for the geometrical influence on fluid flow of settling particles.

  17. Speckle size of light scattered from slightly rough cylindrical surfaces

    NASA Astrophysics Data System (ADS)

    Berlasso, Ricardo G.; Quintian, Fernando Perez; Rebollo, Maria A.; Gaggioli, Nestor G.; Brea, Luis Miguel Sanchez; Martinez, Eusebio Bernabeu

    2002-04-01

    This research is an extension of the optical method of quality control presented in a previous paper [Appl. Opt. 39, 5811 (2000)] to the case of slightly rough cylindrical surfaces. Applying the Kirchhoff scalar diffraction theory yields an analytical expression of the autocorrelation function of the intensity scattered from slightly rough cylindrical surfaces. This function, which is related to speckle size and shape, is shown to depend on the surface correlation length, unlike for plane surfaces for which the speckle depends on the illuminated area only. The theoretical expression is compared with that for the speckle produced by the light scattered from a cylindrical bearing and from various high-quality wires, showing that the method allows the correlation lengths of high-quality cylindrical surfaces to be determined.

  18. Effects of vortex generator on cylindrical protrusion aerodynamics

    NASA Astrophysics Data System (ADS)

    Vignesh Ram, P. S.; Setoguchi, Toshiaki; Kim, Heuy Dong

    2016-02-01

    Experimental and numerical studies were carried out to evaluate the effect of vortex generator on a small cylindrical protrusion at Mach number 2.0. The experiments were performed using the supersonic blow down wind tunnel on different heights of cylindrical protrusion with vortex generator placed ahead of them. The upstream and downstream flow around the cylindrical protrusion is influenced by vortex generator as is observed using both visualization and pressure measurement techniques. Numerical studies using three dimensional steady implicit formulations with standard k-ω turbulence model was performed. Results obtained through the present computation are compared with the experimental results at Mach 2.0. Good agreements between computation and experimental results have been achieved. The results indicate that the aerodynamic drag acting on cylindrical protrusion can be reduced by adopting vortex generator.

  19. Multianode cylindrical proportional counter for high count rates

    DOEpatents

    Hanson, James A.; Kopp, Manfred K.

    1981-01-01

    A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (<60 keV) at count rates of greater than 10.sup.5 counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

  20. Numerical analysis of cocurrent conical and cylindrical axial cyclone separators

    NASA Astrophysics Data System (ADS)

    Nor, M. A. M.; Al-Kayiem, H. H.; Lemma, T. A.

    2015-12-01

    Axial concurrent liquid-liquid separator is seen as an alternative unit to the traditional tangential counter current cyclone due to lower droplet break ups, turbulence and pressure drop. This paper presents the numerical analysis of a new conical axial cocurrent design along with a comparison to the cylindrical axial cocurrent type. The simulation was carried out using CFD technique in ANSYS-FLUENT software. The simulation results were validated by comparison with experimental data from literature, and mesh independency and quality were performed. The analysis indicates that the conical version achieves better separation performance compared to the cylindrical type. Simulation results indicate tangential velocity with 8% higher and axial velocity with 80% lower recirculation compared to the cylindrical type. Also, the flow visualization counters shows smaller recirculation region relative to the cylindrical unit. The proposed conical design seems more efficient and suits the crude/water separation in O&G industry.

  1. Multianode cylindrical proportional counter for high count rates

    DOEpatents

    Hanson, J.A.; Kopp, M.K.

    1980-05-23

    A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (< 60 keV) at count rates of greater than 10/sup 5/ counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

  2. 109. Detail view of structural frame supporting torch arm; cylindrical ...

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

    109. Detail view of structural frame supporting torch arm; cylindrical object in foreground is part of ventilating system. February 1984. - Statue of Liberty, Liberty Island, Manhattan, New York County, NY

  3. Theory and modeling of cylindrical thermo-acoustic transduction

    NASA Astrophysics Data System (ADS)

    Tong, Lihong; Lim, C. W.; Zhao, Xiushao; Geng, Daxing

    2016-06-01

    Models both for solid and thinfilm-solid cylindrical thermo-acoustic transductions are proposed and the corresponding acoustic pressure solutions are obtained. The acoustic pressure for an individual carbon nanotube (CNT) as a function of input power is investigated analytically and it is verified by comparing with the published experimental data. Further numerical analysis on the acoustic pressure response and characteristics for varying input frequency and distance are also examined both for solid and thinfilm-solid cylindrical thermo-acoustic transductions. Through detailed theoretical and numerical studies on the acoustic pressure solution for thinfilm-solid cylindrical transduction, it is concluded that a solid with smaller thermal conductivity favors to improve the acoustic performance. In general, the proposed models are applicable to a variety of cylindrical thermo-acoustic devices performing in different gaseous media.

  4. Effect of SAR on human head modeling inside cylindrical enclosures.

    PubMed

    Mary, T Anita Jones; Ravichandran, C S

    2013-09-01

    This study intends to discuss enclosed a realistic approach to determine and analyze the effects of radio frequency on human exposure inside a cylindrical enclosure. A scenario in which a mobile phone with inverted-F antenna (IFA) operating in the Global System for Mobile Communication (GSM) band (900 MHz) is used inside a cylindrical enclosure. Metallic enclosures are known to have resonance and reflection effects, thereby increasing electric field strength and hence resulting in a change of the human exposure to electromagnetic absorptions. So, this study examines and compares the levels of absorption in terms of specific absorption rate (SAR) values under various conditions. In this study, a human phantom with dielectric properties is designed and its interaction is studied with IFA inside fully enclosed cylindrical enclosures. The results show that SAR values are increased inside cylindrical enclosures compared with those in free space. The method of computation uses method of moments. Simulations are done in FEKO software. PMID:23323517

  5. Cylindrical Cardboard Model for a Rotating System in Special Relativity.

    ERIC Educational Resources Information Center

    Noerdlinger, Peter D.

    1979-01-01

    Presents a cylindrical cardboard model that helps students at the graduate or undergraduate level to visualize the nature of simultaneity and the propagation of light in a rotating coordinate system. (HM)

  6. Eye preferences in captive chimpanzees.

    PubMed

    Braccini, Stephanie N; Lambeth, Susan P; Schapiro, Steven J; Fitch, W Tecumseh

    2012-09-01

    Over the last century, the issue of brain lateralization in primates has been extensively investigated and debated, yet no previous study has reported eye preference in great apes. This study examined eye preference in 45 captive chimpanzees (Pan troglodytes) in response to various stimuli. Eye preference was assessed when animals looked through a hole that only accommodated one eye at an empty box, a mirror, a picture of a dog, a rubber snake, food biscuits, bananas, a rubber duck, and a video camera. Main effects of stimulus type were found for direction of eye preference, number of looks, and looking duration, but not for strength of eye preference. A left-eye bias was found for viewing the rubber snake and a right-eye bias was found for viewing the bananas, supporting theories that emotional valence may affect lateralized behaviors. In addition, a significant shift in eye preference took place from the initial look to subsequent looks when viewing the snake. These results are not consistent with previous reports of human eye preference and may reflect lateralization differences for emotional processing. No relationship between eye preference and previously recorded hand preference was found. PMID:22733385

  7. On burner-stabilized cylindrical premixed flames in microgravity

    NASA Technical Reports Server (NTRS)

    Eng, James A.; Zhu, Delin; Law, Chung K.

    1995-01-01

    An experimental and theoretical program on cylindrical and spherical premixed flames in microgravity has been initiated. We are especially interested in: (1) assessing heat loss versus flow divergence as the dominant stabilization mechanism; (2) understanding the effects of flame curvature on the burning intensity; and (3) determining the laminar burning velocity by using this configuration. In the present study we have performed analytical, computational, and mu g-experimental investigations of the cylindrical flame. The results are presented.

  8. Cylindrical bubbles and blobs from a Class II Hydrophobin

    NASA Astrophysics Data System (ADS)

    Russo, Paul; Pham, Michael; Blalock, Brad

    2012-02-01

    Cerato ulmin is a class II hydrophobin. In aqueous suspensions, it easily forms cylindrical air bubbles and cylindrical oil blobs. The conditions for formation of these unusual structures will be discussed, along with scattering and microscopic investigations of their remarkable stability. Possible applications in diverse fields including polymer synthesis and oil spill remediation will be considered. Acknowledgment is made to Dr. Wayne C. Richards of the Canadian Forest Service for the gift of Cerato ulmin.

  9. On cylindrically converging shock waves shaped by obstacles

    SciTech Connect

    Eliasson, V; Henshaw, W D; Appelo, D

    2007-07-16

    Motivated by recent experiments, numerical simulations were performed of cylindrically converging shock waves. The converging shocks impinged upon a set of zero to sixteen regularly space obstacles. For more than two obstacles the resulting diffracted shock fronts formed polygonal shaped patterns near the point of focus. The maximum pressure and temperature as a function of number of obstacles were studied. The self-similar behavior of cylindrical, triangular and square-shaped shocks were also investigated.

  10. Developing a reversible rapid coordinate transformation model for the cylindrical projection

    NASA Astrophysics Data System (ADS)

    Ye, Si-jing; Yan, Tai-lai; Yue, Yan-li; Lin, Wei-yan; Li, Lin; Yao, Xiao-chuang; Mu, Qin-yun; Li, Yong-qin; Zhu, De-hai

    2016-04-01

    Numerical models are widely used for coordinate transformations. However, in most numerical models, polynomials are generated to approximate "true" geographic coordinates or plane coordinates, and one polynomial is hard to make simultaneously appropriate for both forward and inverse transformations. As there is a transformation rule between geographic coordinates and plane coordinates, how accurate and efficient is the calculation of the coordinate transformation if we construct polynomials to approximate the transformation rule instead of "true" coordinates? In addition, is it preferable to compare models using such polynomials with traditional numerical models with even higher exponents? Focusing on cylindrical projection, this paper reports on a grid-based rapid numerical transformation model - a linear rule approximation model (LRA-model) that constructs linear polynomials to approximate the transformation rule and uses a graticule to alleviate error propagation. Our experiments on cylindrical projection transformation between the WGS 84 Geographic Coordinate System (EPSG 4326) and the WGS 84 UTM ZONE 50N Plane Coordinate System (EPSG 32650) with simulated data demonstrate that the LRA-model exhibits high efficiency, high accuracy, and high stability; is simple and easy to use for both forward and inverse transformations; and can be applied to the transformation of a large amount of data with a requirement of high calculation efficiency. Furthermore, the LRA-model exhibits advantages in terms of calculation efficiency, accuracy and stability for coordinate transformations, compared to the widely used hyperbolic transformation model.

  11. Flow morphologies after oblique shock acceelration of a cylindrical density interface

    NASA Astrophysics Data System (ADS)

    Wayne, Patrick; Simons, Dylan; Olmstead, Dell; Truman, C. Randall; Vorobieff, Peter; Kumar, Sanjay

    2015-11-01

    We present an experimental study of instabilities developing after an oblique shock interaction with a heavy gas column. The heavy gas in our experiments is sulfur hexafluoride infused with 11% acetone by mass. A misalignment of the pressure and density gradients results in three-dimensional vorticity deposition on the gaseous interface, dtriggering the onset of Richtmyer-Meshkov instability (RMI). Shortly thereafter, other instabilities develop along the interface, including a shear-driven instability that presents itself on the leading (with respect to the shock) and trailing edges of the column. This leads to the development of rows of co-rotating ``cat's eye'' vortices, characteristic of Kelvin-Helmholtz instability (KHI). Characteristics of the KHI, such as growth rate and wavelength, depend on several factors including the Mach number of the shock, the shock tube angle of inclination α (equal to the angle between the axis of the column and the plane of the shock), and the Atwood number. This work is supported by the US National Nuclear Security Agency (NNSA) via grant DE-NA0002913.

  12. Linac mechanic QA using a cylindrical phantom

    NASA Astrophysics Data System (ADS)

    Mamalui-Hunter, Maria; Li, Harold; Low, Daniel A.

    2008-09-01

    Precise mechanical operation of a linear accelerator (linac) is critical for accurate radiation therapy dose delivery. Quantitative procedures for linac mechanical quality assurance (QA) used in the standard of care are time consuming and therefore conducted on a relatively infrequent basis. We present a method for evaluating the mechanical performance of a linac based on a series of projection portal images of a prototype cylindrical phantom with embedded radiopaque fiducial markers. The marker autodetection process included modeling imager response to the radiation beam where the projected cylinder attenuation yielded a non-uniform image background. The linac mechanical characteristics were estimated based on nonlinear multi-objective optimization of the projected marker locations. The estimated geometry parameters for the tested commercial model were gantry angle deviation 0.075 ± 0.076° (1 SD), gantry sag 0.026 ± 0.02°, source-to-axis distance SAD 998.3 ± 1.7 mm, source-to-detector distance SDD 1493 ± 5.0 mm, couch vertical motion 0.6 ± 0.45 mm, couch rotation 0.154 ± 0.1° and average linac rotation center (1.02, -0.27, -0.37) ± (0.36,0.333,1.20) mm relative to the laser intersection. The imager shift was [-0.44, 2.6] ± [0.20, 1.1] mm and the imager orientation was in-plane rotation 0.05 ± 0.03°, roll -0.14 ± 0.09° and pitch -0.9 ± 0.604°. The performance of this procedure concerning marker detection and optimization was examined by comparing the detected set of marker coordinates to its back-calculated counterpart for three subgroups of markers: central, wall and intermediate relative to the center of the phantom. The maximum difference was less than 0.25 mm with a mean of 0.146 mm and a standard deviation of 0.07 mm. The clinical use of this automated procedure will allow more efficient, more thorough, and more frequent mechanical linac QA.

  13. Linac mechanic QA using a cylindrical phantom.

    PubMed

    Mamalui-Hunter, Maria; Li, Harold; Low, Daniel A

    2008-09-21

    Precise mechanical operation of a linear accelerator (linac) is critical for accurate radiation therapy dose delivery. Quantitative procedures for linac mechanical quality assurance (QA) used in the standard of care are time consuming and therefore conducted on a relatively infrequent basis. We present a method for evaluating the mechanical performance of a linac based on a series of projection portal images of a prototype cylindrical phantom with embedded radiopaque fiducial markers. The marker autodetection process included modeling imager response to the radiation beam where the projected cylinder attenuation yielded a non-uniform image background. The linac mechanical characteristics were estimated based on nonlinear multi-objective optimization of the projected marker locations. The estimated geometry parameters for the tested commercial model were gantry angle deviation 0.075 +/- 0.076 degrees (1 SD), gantry sag 0.026 +/- 0.02 degrees , source-to-axis distance SAD 998.3 +/- 1.7 mm, source-to-detector distance SDD 1493 +/- 5.0 mm, couch vertical motion 0.6 +/- 0.45 mm, couch rotation 0.154 +/- 0.1 degrees and average linac rotation center (1.02, -0.27, -0.37) +/- (0.36,0.333,1.20) mm relative to the laser intersection. The imager shift was [-0.44, 2.6] +/- [0.20, 1.1] mm and the imager orientation was in-plane rotation 0.05 +/- 0.03 degrees , roll -0.14 +/- 0.09 degrees and pitch -0.9 +/- 0.604 degrees . The performance of this procedure concerning marker detection and optimization was examined by comparing the detected set of marker coordinates to its back-calculated counterpart for three subgroups of markers: central, wall and intermediate relative to the center of the phantom. The maximum difference was less than 0.25 mm with a mean of 0.146 mm and a standard deviation of 0.07 mm. The clinical use of this automated procedure will allow more efficient, more thorough, and more frequent mechanical linac QA. PMID:18723927

  14. Asymmetric Bulkheads for Cylindrical Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Ford, Donald B.

    2007-01-01

    Asymmetric bulkheads are proposed for the ends of vertically oriented cylindrical pressure vessels. These bulkheads, which would feature both convex and concave contours, would offer advantages over purely convex, purely concave, and flat bulkheads (see figure). Intended originally to be applied to large tanks that hold propellant liquids for launching spacecraft, the asymmetric-bulkhead concept may also be attractive for terrestrial pressure vessels for which there are requirements to maximize volumetric and mass efficiencies. A description of the relative advantages and disadvantages of prior symmetric bulkhead configurations is prerequisite to understanding the advantages of the proposed asymmetric configuration: In order to obtain adequate strength, flat bulkheads must be made thicker, relative to concave and convex bulkheads; the difference in thickness is such that, other things being equal, pressure vessels with flat bulkheads must be made heavier than ones with concave or convex bulkheads. Convex bulkhead designs increase overall tank lengths, thereby necessitating additional supporting structure for keeping tanks vertical. Concave bulkhead configurations increase tank lengths and detract from volumetric efficiency, even though they do not necessitate additional supporting structure. The shape of a bulkhead affects the proportion of residual fluid in a tank that is, the portion of fluid that unavoidably remains in the tank during outflow and hence cannot be used. In this regard, a flat bulkhead is disadvantageous in two respects: (1) It lacks a single low point for optimum placement of an outlet and (2) a vortex that forms at the outlet during outflow prevents a relatively large amount of fluid from leaving the tank. A concave bulkhead also lacks a single low point for optimum placement of an outlet. Like purely concave and purely convex bulkhead configurations, the proposed asymmetric bulkhead configurations would be more mass-efficient than is the flat

  15. Voter-Weighted Environmental Preferences

    ERIC Educational Resources Information Center

    Bell, Jason; Huber, Joel; Viscusi, W. Kip

    2009-01-01

    This article examines the political economy of preferences with respect to the environment using a new stated preference survey that presents the first benefit values for national water quality levels. The mean valuation greatly exceeds the median value, as the distribution of valuations is highly skewed. The study couples the survey valuations…

  16. Music, Hemisphere Preference and Imagery.

    ERIC Educational Resources Information Center

    Stratton, Valerie N.; Zalanowski, Annette H.

    Two experiments were conducted to determine a possible relationship between the right hemisphere, music perception, and mental imagery. The first experiment compared two groups of college students, one of which showed a preference for left hemisphere thinking (n=22) and the other a preference for right hemisphere thinking (n=20), in order to test…

  17. Preferences for Academic Advising Styles

    ERIC Educational Resources Information Center

    Weir, Susan B.; Dickman, Marcia M.; Fuqua, Dale R.

    2005-01-01

    This psychometric study was designed to test the feasibility of measuring college students' preferences for developmental and prescriptive advising styles as separate constructs. Part 5 of the Academic Advising Inventory (Winston & Sandor, 1984b) was revised into two independent scales, one for measuring preferences for developmental advising and…

  18. Squirrel Foraging Preferences: Gone Nuts?

    ERIC Educational Resources Information Center

    Darling, Randi A.

    2007-01-01

    This field exercise examines the feeding preferences of Gray Squirrels ("Sciurus carolinensis"). Students present squirrels with a variety of food types in a cafeteria-style arrangement in order to test hypotheses about foraging preferences. This exercise, which is appropriate for introductory biology, ecology, and animal behavior classes, is…

  19. Assessing Preference for Social Interactions

    ERIC Educational Resources Information Center

    Clay, Casey J.; Samaha, Andrew L.; Bloom, Sarah E.; Bogoev, Bistra K.; Boyle, Megan A.

    2013-01-01

    We examined a procedure to assess preference for social interactions in individuals with intellectual and developmental disabilities. Preferences were identified in five individuals using a paired-choice procedure in which participants approached therapists who provided different forms of social interactions. A subsequent tracking test showed that…

  20. Gender Preferences in Learning Science.

    ERIC Educational Resources Information Center

    Stark, Rae; Gray, Donald

    1999-01-01

    Reports on preference patterns among gender and age groups for school-science topics and learning experiences among respondents chosen to be nationally representative of Scottish primary and secondary pupils. Finds that girls have a stronger preference for biological topics than boys. Concludes that much of what goes on in science classrooms is…

  1. Children Reason about Shared Preferences

    ERIC Educational Resources Information Center

    Fawcett, Christine A.; Markson, Lori

    2010-01-01

    Two-year-old children's reasoning about the relation between their own and others' preferences was investigated across two studies. In Experiment 1, children first observed 2 actors display their individual preferences for various toys. Children were then asked to make inferences about new, visually inaccessible toys and books that were described…

  2. Temporal Constraint Reasoning With Preferences

    NASA Technical Reports Server (NTRS)

    Khatib, Lina; Morris, Paul; Morris, Robert; Rossi, Francesca

    2001-01-01

    A number of reasoning problems involving the manipulation of temporal information can naturally be viewed as implicitly inducing an ordering of potential local decisions involving time (specifically, associated with durations or orderings of events) on the basis of preferences. For example. a pair of events might be constrained to occur in a certain order, and, in addition. it might be preferable that the delay between them be as large, or as small, as possible. This paper explores problems in which a set of temporal constraints is specified, where each constraint is associated with preference criteria for making local decisions about the events involved in the constraint, and a reasoner must infer a complete solution to the problem such that, to the extent possible, these local preferences are met in the best way. A constraint framework for reasoning about time is generalized to allow for preferences over event distances and durations, and we study the complexity of solving problems in the resulting formalism. It is shown that while in general such problems are NP-hard, some restrictions on the shape of the preference functions, and on the structure of the preference set, can be enforced to achieve tractability. In these cases, a simple generalization of a single-source shortest path algorithm can be used to compute a globally preferred solution in polynomial time.

  3. Scattering of cylindrical electric field waves from an elliptical dielectric cylindrical shell

    NASA Astrophysics Data System (ADS)

    Urbanik, E. A.

    1982-12-01

    This thesis examines the scattering of cylindrical waves by large dielectric scatterers of elliptic cross section. The solution method was the method of moments using a Galerkin approach. Sinusoidal basis and testing functions were used resulting in a higher convergence rate. The higher rate of convergence made it possible for the program to run on the Aeronautical Systems Division's CYBER computers without any special storage methods. This report includes discussion on moment methods, solution of integral equations, and the relationship between the electric field and the source region or self cell singularity. Since the program produced unacceptable run times, no results are contained herein. The importance of this work is the evaluation of the practicality of moment methods using standard techniques. The long run times for a mid-sized scatterer demonstrate the impracticality of moment methods for dielectrics using standard techniques.

  4. The Speed of Axial Propagation of a Cylindrical Bubble Through a Cylindrical Vortex

    NASA Technical Reports Server (NTRS)

    Shariff, Karim; Mansour, Nagi N. (Technical Monitor)

    2002-01-01

    Inspired by the rapid elongation of air columns injected into vortices by dolphins, we present an exact inviscid solution for the axial speed (assumed steady) of propagation of the tip of a semi-infinite cylindrical bubble along the axis of a cylindrical vortex. The bubble is assumed to be held at constant pressure by being connected to a reservoir, the lungs of the dolphin, say. For a given bubble pressure, there is a modest critical rotation rate above which steadily propagating bubbles exist. For a bubble at ambient pressure, the propagation speed of the bubble (relative to axial velocity within the vortex) varies between 0.5 and 0.6 of the maximum rotational speed of the vortex. Surprisingly, the bubble tip can propagate (almost as rapidly) even when the pressure minimum in the vortex core is greater than the bubble pressure; in this case, solutions exhibit a dimple on the nose of the bubble. A situation important for incipient vortex cavitation, and one which dolphins also demonstrate, is elongation of a free bubble, i.e., one whose internal pressure may vary. Under the assumption that the acceleration term is small (checked a posteriori), the steady solution is applied at each instant during the elongation. Three types of behavior are then possible depending on physical parameters and initial conditions: (A) Unabated elongation with slowly increasing bubble pressure, and nearly constant volume. Volume begins to decrease in the late stages. (B1) Elongation with decreasing bubble pressure. A limit point of the steady solution is encountered at a finite bubble length. (B2) Unabated elongation with decreasing bubble pressure and indefinite creation of volume. This is made possible by the existence of propagating solutions at bubble pressures below the minimum vortex pressure. As the bubble stretches, its radius initially decreases but then becomes constant; this is also observed in experiments on incipient vortex cavitation.

  5. Preferences in Data Production Planning

    NASA Technical Reports Server (NTRS)

    Golden, Keith; Brafman, Ronen; Pang, Wanlin

    2005-01-01

    This paper discusses the data production problem, which consists of transforming a set of (initial) input data into a set of (goal) output data. There are typically many choices among input data and processing algorithms, each leading to significantly different end products. To discriminate among these choices, the planner supports an input language that provides a number of constructs for specifying user preferences over data (and plan) properties. We discuss these preference constructs, how we handle them to guide search, and additional challenges in the area of preference management that this important application domain offers.

  6. Optical testing of cylindrical surfaces with computer-generated holograms

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Guo, Pei-ji

    2013-08-01

    Increasing demands for highly accurate cylinders require more high-precision testing techniques. The existing methods of testing cylindrical surfaces can not ensure the highly-accuracy, efficiency, convenience and the overall cost. In order to acquire highly accurate cylindrical surfaces conveniently at a low cost, a new Fizeau interferometric optical testing utilizing CGH which is fabricated onto a wedge-shaped substrate is designed. In this test, a slit filter is placed in the center of the cylindrical curvature to filter out the undesired diffraction orders which occur when the beam hits the CGH. Meanwhile, the front side of the wedge-shaped substrate is as the reference flat, and the CGH is written onto the inclined surface, so that the real fringe pattern can not be affected by its reflected beam. Moreover, the design of cylindrical surfaces under test tilting and off-center relative to the diffraction surface of the CGH results that the required rays for interference can be obtained effectively from the pinhole filter in the interferometer. Furthermore, high-accuracy CGH in this test can be processed by conventional microlithography equipments. Corresponding to a cylindrical surface with 60mm in diameter and f-number of 1/7, the test has been successfully designed and optimized in Zemax whose testing accuracy is prior to 0.0019λ. Better interference pattern can be obtained because all the other disturbing rays image outside of aperture in a radius of 2mm. Experiment shows the method is efficient and predominant.

  7. Novel spherical hohlraum with cylindrical laser entrance holes and shields

    SciTech Connect

    Lan, Ke; Zheng, Wudi

    2014-09-15

    Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles > 45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums.

  8. Monolithic Cylindrical Fused Silica Resonators with High Q Factors.

    PubMed

    Pan, Yao; Wang, Dongya; Wang, Yanyan; Liu, Jianping; Wu, Suyong; Qu, Tianliang; Yang, Kaiyong; Luo, Hui

    2016-01-01

    The cylindrical resonator gyroscope (CRG) is a typical Coriolis vibratory gyroscope whose performance is determined by the Q factor and frequency mismatch of the cylindrical resonator. Enhancing the Q factor is crucial for improving the rate sensitivity and noise performance of the CRG. In this paper, for the first time, a monolithic cylindrical fused silica resonator with a Q factor approaching 8 × 10⁵ (ring-down time over 1 min) is reported. The resonator is made of fused silica with low internal friction and high isotropy, with a diameter of 25 mm and a center frequency of 3974.35 Hz. The structure of the resonator is first briefly introduced, and then the experimental non-contact characterization method is presented. In addition, the post-fabrication experimental procedure of Q factor improvement, including chemical and thermal treatment, is demonstrated. The Q factor improvement by both treatments is compared and the primary loss mechanism is analyzed. To the best of our knowledge, the work presented in this paper represents the highest reported Q factor for a cylindrical resonator. The proposed monolithic cylindrical fused silica resonator may enable high performance inertial sensing with standard manufacturing process and simple post-fabrication treatment. PMID:27483263

  9. Elliptic cylindrical silicon nanowire hybrid surface plasmon polariton waveguide.

    PubMed

    Zhang, Li; Xiong, Qiulin; Li, Xiaopeng; Ma, Junxian

    2015-08-10

    We researched an elliptic cylindrical silicon nanowire hybrid surface plasmon polariton waveguide and evaluated its mode characteristics using the finite element method software COMSOL. The waveguide consists of three parts: an elliptic cylindrical silicon nanowire, a silver film layer, and a silica covering layer between them. All of the components are surrounded by air. After optimizing the geometrical parameters of the waveguide, we can achieve the waveguide's strong field confinement (ranging from λ2/270 to λ2/27) and long propagation distances (119-485 μm). In order to further understand the impact of the waveguide's architecture on its performance, we also studied the ridge hybrid waveguide. The results show that the ridge waveguide has moderate local field confinement ranging from λ2/190 to λ2/20 and its maximum propagation distance is about 340 μm. We compared the elliptic cylindrical and ridge nanowire hybrid waveguides with the cylindrical hybrid waveguide that we studied before. The elliptic cylindrical waveguide achieves a better trade-off between reasonable mode confinement and maximum propagation length in the three waveguides. The researched hybrid surface plasmon polaritons waveguides are useful to construct devices such as a directional coupler and may find potential applications in photonic integrated circuits or other novel SPP devices. PMID:26368373

  10. Effect of cylindrical confinement on the determination of laminar flame speeds using outwardly propagating flames

    SciTech Connect

    Burke, Michael P.; Chen, Zheng; Ju, Yiguang; Dryer, Frederick L.

    2009-04-15

    elevated pressures. Flow-corrected flame speeds in the small cylindrical chamber used here agree well with previously reported flame speeds from large spherical chambers. Previous papers presenting burning velocities from cylindrical chambers report performing data analysis on flame radii less than 0.5 or 0.6 times the wall radius, where the flame speed calculated neglecting confinement effects may be low by {proportional_to}15 or 20%, respectively. For cylindrical chambers, data analysis should be restricted to flame radii less than 0.3 times the wall radius or a flow correction should be employed to account for the burned gas motions. With regard to the design of future vessels, larger vessels that minimize the flow aberrations for the same flame radius are preferred. Larger vessels maximize the relatively unaffected region of data allowing for a more straightforward approach to interpret the experimental data. (author)

  11. There is more to the picture than meets the rat: a study on rodent geometric shape and proportion preferences.

    PubMed

    Winne, Jéssica; Teixeira, Leslie; de Andrade Pessoa, Jéssica; Gavioli, Elaine Cristina; Soares-Rachetti, Vanessa; André, Eunice; Lobão-Soares, Bruno

    2015-05-01

    In rodents, the novel object preference test has been used as a behavioral parameter for evaluation of neotic exploratory behavior, and also for memory consolidation tasks. Geometric patterns of this preference are poorly understood, and may vary among species. We evaluated in Wistar rats (Rattus norvergicus) a possible exploration preference considering aluminum tripartite rounded and cylindrical objects of different proportions: 1.2; 1.618; 1.8. At the first day, animals were exposed to 1.2; 1.6 and 1.8 rounded objects. At 24h after, these animals were exposed to the same objects, together with three new steel cylindrical objects (same proportions). ANOVA and T tests were used to quantify object exploration for each animal (p<0.05). Data analysis pointed to a longer exploration time of the object 1.2 at the three different protocols indicating a preference pattern on the first day exposition. On the second day the exploration was similar in both familiar and unfamiliar objects, revealing no novel object preference for cylinders. However, we found an object preference related to the 1.2 proportion (balls plus cylinders), in two of three position protocols. In addition, on a single exposition with both cylinders and rounded objects, rats revealed a rounded object preference. The 1.2 preference disclosed by rats also reflected the proportion of their body. From nine main measures of body ratios, seven were close to 1.2 ratio. The correspondence between body ratios and object preference may be explained by habituation learning and by sexual selection, and highlight innate factors regarding aesthetic preferences among species. PMID:25698599

  12. Centimeter to Decimeter Size Spherical and Cylindrical Features in Gale Crater Sediments

    NASA Technical Reports Server (NTRS)

    Wiens, R. C.; Maurice, S.; Gasnault, O.; Clegg, S.; Fabre, C.; Nachon, M.; Rubin, D.; Goetz, W.; Mangold, N.; Schroeder, S.; Rapin, W.; Milliken, R.; Fairen, A. G.; Oehler, D.; Forni, O.; Sautter, V.; Blaney, D.; Le Moulelic, S.; Anderson, R. B.; Cousin, A.; Vasavada, A.; Grotzinger, J.

    2015-01-01

    The Curiosity rover traverse in Gale crater has explored a large series of sedimentary deposits in an ancient lake on Mars. Over the nine kilometers of traverse a recurrent observation has been southward-dipping sedimentary strata, from Shaler at the edge of Yellowknife Bay to the striated units near the Kimberley. Within the sedimentary strata cm- to decimeter- size hollow spheroidal objects and some apparent cylindrical objects have been observed. These features have not been seen by previous landed missions. The first of these were observed on sol 122 in the Gillespie Lake member at Yellowknife Bay. Additional hollow features were observed in the Point Lake outcrop in the same area. More recently a spherical and apparently hollow object, Winnipesaukee, was observed by ChemCam and Mastcam on sol 653. Here we describe the settings, morphology, and associated compositions, and we discuss possible origins of these objects.

  13. A method based on IHS cylindrical transform model for quality assessment of image fusion

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaokun; Jia, Yonghong

    2005-10-01

    Image fusion technique has been widely applied to remote sensing image analysis and processing, and methods for quality assessment of image fusion in remote sensing have also become the research issues at home and abroad. Traditional assessment methods combine calculation of quantitative indexes and visual interpretation to compare fused images quantificationally and qualitatively. However, in the existing assessment methods, there are two defects: on one hand, most imdexes lack the theoretic support to compare different fusion methods. On the hand, there is not a uniform preference for most of the quantitative assessment indexes when they are applied to estimate the fusion effects. That is, the spatial resolution and spectral feature could not be analyzed synchronously by these indexes and there is not a general method to unify the spatial and spectral feature assessment. So in this paper, on the basis of the approximate general model of four traditional fusion methods, including Intensity Hue Saturation(IHS) triangle transform fusion, High Pass Filter(HPF) fusion, Principal Component Analysis(PCA) fusion, Wavelet Transform(WT) fusion, a correlation coefficient assessment method based on IHS cylindrical transform is proposed. By experiments, this method can not only get the evaluation results of spatial and spectral features on the basis of uniform preference, but also can acquire the comparison between fusion image sources and fused images, and acquire differences among fusion methods. Compared with the traditional assessment methods, the new methods is more intuitionistic, and in accord with subjective estimation.

  14. Radiation and scattering from printed antennas on cylindrically conformal platforms

    NASA Technical Reports Server (NTRS)

    Kempel, Leo C.; Volakis, John L.; Bindiganavale, Sunil

    1994-01-01

    The goal was to develop suitable methods and software for the analysis of antennas on cylindrical coated and uncoated platforms. Specifically, the finite element boundary integral and finite element ABC methods were employed successfully and associated software were developed for the analysis and design of wraparound and discrete cavity-backed arrays situated on cylindrical platforms. This work led to the successful implementation of analysis software for such antennas. Developments which played a role in this respect are the efficient implementation of the 3D Green's function for a metallic cylinder, the incorporation of the fast Fourier transform in computing the matrix-vector products executed in the solver of the finite element-boundary integral system, and the development of a new absorbing boundary condition for terminating the finite element mesh on cylindrical surfaces.

  15. Optimization of electrodynamic acceleration regimes for cylindrical conductors

    NASA Astrophysics Data System (ADS)

    Kalikhman, S. A.

    1985-11-01

    At the present time electromagnetic accelerators which use the action of an impulsive electromagnetic field on a current-carrying conductor appear to be promising devices for the study of high-speed collisions. In the regime using separate sources for the accelerating magnetic field and the current in the conductor being accelerated it is possible to bring cylindrical conductors up to velocities exceeding 12 km/sec [1]. Acceleration regimes have been calculated previously [2] assuming independence of the current density in the conductor from the accelerating magnetic field. However, as analysis of transient electromagnetic processes occurring in the interaction of an impulsive electromagnetic field with a cylindrical conductor shows [3], the maximum current density, limited by heating conditions, depends significantly on the induction of the accelerating magnetic field. In the present study we will analyze regimes for electrodynamic acceleration of cylindrical conductors with consideration of diffusion of both the intrinsic and the external impulsive magnetic field within the conductor.

  16. Determination of thermal diffusivities of cylindrical bodies being cooled

    SciTech Connect

    Dincer, I.

    1996-09-01

    This paper deals with the development of an analytical model for determining the thermal diffusivities of the individual solid cylindrical bodies subjected to cooling is presented. Applications of this model were made using the experimental center temperature data obtained from the cylindrical products (e.g., cucumber and grape) during air cooling at the flow velocity of 2 m/s. As an experimental result, the thermal diffusivities of products were found to be 1.45{times}10{sup {minus}7} m{sup 2}/s for cucumber and 1.68{times}10{sup {minus}7} m{sup 2}/s for grape. It can be concluded that the present model is capable of determining the thermal diffusivities of cylindrical bodies during cooling in a simple and effective form.

  17. Experiments of cylindrical isentropic compression by ultrahigh magnetic field

    NASA Astrophysics Data System (ADS)

    Gu, Zhuowei; Zhou, Zhongyu; Zhang, Chunbo; Tang, Xiaosong; Tong, Yanjin; Zhao, Jianheng; Sun, Chengwei

    2015-09-01

    The high Explosive Magnetic Flux Implosion Compression Generator (EMFICG) is a kind of unique high energy density dynamic technique with characters like ultrahigh pressure and low temperature rising and could be suitable as a tool of cylindrical isentropic compression. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) have developed EMFICG technique and realized cylindrical isentropic compression. In the experiments, a seed magnetic field of 5-6 Tesla were built first and compressed by a stainless steel liner which is driven by high explosive. The inner free surface velocity of sample was measured by PDV. The isentropic compression of a copper sample was verified and the isentropic pressure is over 100 GPa. The cylindrical isentropic compression process has been numerical simulated by 1D MHD code and the simulation results were compared with the experiments. Compared with the transitional X-ray flash radiograph measurement, this method will probably promote the data accuracy.

  18. Resonance in cylindrical-rectangular and wraparound microstrip structures

    NASA Technical Reports Server (NTRS)

    Ali, Sami M.; Kong, Jin AU; Habashy, Tarek M.; Kiang, Jean-Fu

    1989-01-01

    A rigorous analysis of the resonance frequency problem of both the cylindrical-rectangular and the wraparound microstrip structure is presented. The problem is formulated in terms of a set of vector integral equations. Using Galerkin's method to solve the integral equations, the complex resonance frequencies are studied with sinusoidal basis functions which incorporate the edge singularity. The complex resonance frequencies are computed using a perturbation approach. Modes suitable for resonator or antenna applications are investigated. The edge singularity of the patch current is shown to have no significant effect on the accuracy of the results. It is shown that the HE10 modes of the cylindrical-rectangular and wraparound patches are more appropriate for resonator applications. The HE01 and TE01 modes of the cylindrical-rectangular and wraparound patches, respectively, are efficient radiating modes.

  19. Rotating cylindrical magnetron sputtering: Simulation of the reactive process

    SciTech Connect

    Depla, D.; Mahieu, S.; Van Aeken, K.; Leroy, W. P.; Haemers, J.; De Gryse, R.; Li, X. Y.; Bogaerts, A.

    2010-06-15

    A rotating cylindrical magnetron consists of a cylindrical tube, functioning as the cathode, which rotates around a stationary magnet assembly. In stationary mode, the cylindrical magnetron behaves similar to a planar magnetron with respect to the influence of reactive gas addition to the plasma. However, the transition from metallic mode to poisoned mode and vice versa depends on the rotation speed. An existing model has been modified to simulate the influence of target rotation on the well known hysteresis behavior during reactive magnetron sputtering. The model shows that the existing poisoning mechanisms, i.e., chemisorption, direct reactive ion implantation and knock on implantation, are insufficient to describe the poisoning behavior of the rotating target. A better description of the process is only possible by including the deposition of sputtered material on the target.

  20. Alcohol demand and risk preference

    PubMed Central

    Dave, Dhaval; Saffer, Henry

    2008-01-01

    Both economists and psychologists have studied the concept of risk preference. Economists categorize individuals as more or less risk-tolerant based on the marginal utility of income. Psychologists categorize individuals' propensity towards risk based on harm avoidance, novelty seeking and reward dependence traits. The two concepts of risk are related, although the instruments used for empirical measurement are quite different. Psychologists have found risk preference to be an important determinant of alcohol consumption; however economists have not included risk preference in studies of alcohol demand. This is the first study to examine the effect of risk preference on alcohol consumption in the context of a demand function. The specifications employ multiple waves from the Panel Study of Income Dynamics (PSID) and the Health and Retirement Study (HRS), which permit the estimation of age-specific models based on nationally representative samples. Both of these data sets include a unique and consistent survey instrument designed to directly measure risk preference in accordance with the economist's definition. This study estimates the direct impact of risk preference on alcohol demand and also explores how risk preference affects the price elasticity of demand. The empirical results indicate that risk preference has a significant negative effect on alcohol consumption, with the prevalence and consumption among risk-tolerant individuals being 6–8% higher. Furthermore, the tax elasticity is similar across both risk-averse and risk-tolerant individuals. This suggests that tax policies are as equally effective in deterring alcohol consumption among those who have a higher versus a lower propensity for alcohol use. PMID:19956353

  1. Alcohol demand and risk preference.

    PubMed

    Dave, Dhaval; Saffer, Henry

    2008-12-01

    Both economists and psychologists have studied the concept of risk preference. Economists categorize individuals as more or less risk-tolerant based on the marginal utility of income. Psychologists categorize individuals' propensity towards risk based on harm avoidance, novelty seeking and reward dependence traits. The two concepts of risk are related, although the instruments used for empirical measurement are quite different. Psychologists have found risk preference to be an important determinant of alcohol consumption; however economists have not included risk preference in studies of alcohol demand. This is the first study to examine the effect of risk preference on alcohol consumption in the context of a demand function. The specifications employ multiple waves from the Panel Study of Income Dynamics (PSID) and the Health and Retirement Study (HRS), which permit the estimation of age-specific models based on nationally representative samples. Both of these data sets include a unique and consistent survey instrument designed to directly measure risk preference in accordance with the economist's definition. This study estimates the direct impact of risk preference on alcohol demand and also explores how risk preference affects the price elasticity of demand. The empirical results indicate that risk preference has a significant negative effect on alcohol consumption, with the prevalence and consumption among risk-tolerant individuals being 6-8% higher. Furthermore, the tax elasticity is similar across both risk-averse and risk-tolerant individuals. This suggests that tax policies are as equally effective in deterring alcohol consumption among those who have a higher versus a lower propensity for alcohol use. PMID:19956353

  2. Human preference for individual colors

    NASA Astrophysics Data System (ADS)

    Palmer, Stephen E.; Schloss, Karen B.

    2010-02-01

    Color preference is an important aspect of human behavior, but little is known about why people like some colors more than others. Recent results from the Berkeley Color Project (BCP) provide detailed measurements of preferences among 32 chromatic colors as well as other relevant aspects of color perception. We describe the fit of several color preference models, including ones based on cone outputs, color-emotion associations, and Palmer and Schloss's ecological valence theory. The ecological valence theory postulates that color serves an adaptive "steering' function, analogous to taste preferences, biasing organisms to approach advantageous objects and avoid disadvantageous ones. It predicts that people will tend to like colors to the extent that they like the objects that are characteristically that color, averaged over all such objects. The ecological valence theory predicts 80% of the variance in average color preference ratings from the Weighted Affective Valence Estimates (WAVEs) of correspondingly colored objects, much more variance than any of the other models. We also describe how hue preferences for single colors differ as a function of gender, expertise, culture, social institutions, and perceptual experience.

  3. Parametric Investigations of Miniaturized Cylindrical and Annular Hall Thrusters

    SciTech Connect

    A. Smirnov; Y. Raitses; N.J. Fisch

    2001-10-16

    A cylindrical geometry Hall thruster may overcome certain physical and technological limitations in scaling down of Hall thrusters to miniature sizes. The absence of the inner wall and use of the cusp magnetic field can potentially reduce heating of the thruster parts and erosion of the channel. A 2.6 cm miniaturized Hall thruster of a flexible design was built and successfully operated in the power range of 50-300 W. Comparison of preliminary results obtained for cylindrical and annular thruster configurations is presented.

  4. Cylindrical diffuser axial detection profile is dependent on fiber design

    PubMed Central

    Baran, Timothy M.

    2015-01-01

    Abstract. The axial emission and detection profiles of 1- and 2-cm cylindrical diffusing fibers based on concentration gradients of scatterers were measured. Based on these measurements, we describe a method for determination of the scatterer concentration gradient within the diffusers. Using a Monte Carlo model incorporating these concentrations, detection was simulated and found to agree with measurements. The measured and simulated detection profiles for these diffusers were found to be drastically different from those previously measured in an alternative diffuser design incorporating an end reflector. When using cylindrical diffusers as detection fibers, it is, therefore, important to understand the design of the fiber and characterize the detection behavior. PMID:25839428

  5. Non-modal analysis of the diocotron instability: Cylindrical geometry

    SciTech Connect

    Mikhailenko, V. V.; Lee, Hae June; Mikhailenko, V. S.; Azarenkov, N. A.

    2013-04-15

    The temporal evolution of the linear diocotron instability of the cylindrical annular plasma column is investigated by employing the extension of the shearing modes methodology to the cylindrical geometry. It was obtained that the spatial time-dependent distortion of the electron density initial perturbations by shear flows leads to the non-modal evolution of the potential, which was referred to as the manifestation of the continuous spectrum. The evolution process leads toward the convergence to the phase-locking configuration of the mutually growing normal modes.

  6. Stabilization Mechanisms and Burning Rates of Cylindrical Burner Flames

    NASA Technical Reports Server (NTRS)

    Eng, J. A.; Law, C. K.; Zhu, D. L.

    1994-01-01

    A study is conducted of the structure and response of curved (but unstretched), cylindrically-symmetric 1D premixed flames from a cylindrical porous burner. The study has employed (1) activation-energy asymptotics with one-step reaction constant and constant properties; (2) a numerical computation which encompassed detailed chemistry and transport behavior, and (3) drop-tower microgravity tests. Attention was given to the relative importance of heat loss vs. flow divergence as the dominant mechanism for flame stabilization; the results show that, with increasing flow discharge rate, the dominant flame stabilization mechanism changes from heat loss to flow divergence.

  7. 2DEG on a cylindrical shell with a screw dislocation

    NASA Astrophysics Data System (ADS)

    Filgueiras, Cleverson; Silva, Edilberto O.

    2015-09-01

    A two dimensional electron gas on a cylindrical surface with a screw dislocation is considered. More precisely, we investigate how both the geometry and the deformed potential due to a lattice distortion affect the Landau levels of such system. The case showing the deformed potential can be thought in the context of 3D common semiconductors where the electrons are confined on a cylindrical shell. We will show that important quantitative differences exist due to this lattice distortion. For instance, the effective cyclotron frequency is diminished by the deformed potential, which in turn enhances the Hall conductivity.

  8. Postbuckling analysis of composite laminated cylindrical panels under axial compression

    NASA Astrophysics Data System (ADS)

    Kweon, J. H.; Hong, C. S.

    1993-08-01

    The nonlinear finite element method is used to analyze the postbuckling behavior of composite laminated cylindrical panels with various stacking sequences under compression. The analysis is based on the updated Lagrangian formulation, an eight-node degenerated shell element, and an improved load-increment method based on the arc-length scheme. Results reveal that the postbuckling loads carrying capacities of laminated cylindrical panels under compression are largely dependent on the bending stiffness component. Not only the buckling loads but also the postbuckling load-carrying capacities should be considered in designing the structure.

  9. Aerodynamic sound generation induced by flow over small, cylindrical cavities

    NASA Technical Reports Server (NTRS)

    Parthasarathy, S. P.; Cho, Y. I.; Back, L. H.

    1984-01-01

    An experimental investigation has been conducted on the production of high intensity tones by small cylindrical cavities in a flat surface. The application of such a mechanism is to the acoustic coding of moving objects containing drilled holes. The sound intensity and frequency have been determined as functions of flow velocity, diameter and depth of the cavities. As a practical matter, it is possible to produce a whistle producing 106 dB at 30.5 cm distance from a cylindrical hole of 0.5 cm diameter and 1.2 cm deep with an airflow of 60 m/s past the hole.

  10. Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium

    PubMed Central

    Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying

    2015-01-01

    A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium. PMID:26073066

  11. Incorrectness of the usual gyrokinetic treatment in cylindrically symmetric systems

    SciTech Connect

    Linsker, R.

    1980-07-01

    It is shown that the usual gyrokinetic theory does not consistently retain all terms of leading order in the expansion parameter epsilon = gyroradius/equilibrium scale length. This is illustrated for cylindrically symmetric systems by comparing the perturbed distribution function calculated by the gyrokinetic method with that obtained by explicitly integrating the Vlasov equation over the unperturbed orbit. The integral equation used in some recent treatments of drift waves in sheared-slab geometry is shown to be incorrect. The correct calculation of the ion density perturbation for a collisionless ..beta.. = 0 plasma with cylindrical symmetry is presented.

  12. Azimuthally-dependent Finite Element Solution to the Cylindrical Resonator

    NASA Technical Reports Server (NTRS)

    Osegueda, R.; Pierluissi, J.; Gil, L.; Revilla, A.; Villalva, G.; Dick, G.; Wang, D. SantiagoR.

    1994-01-01

    The cylindrical cavity resonator loaded with an anisotropic dielectric is analyzed as a two-dimensional problem using a finite element approach that assumes sinusoidal dependence in azimuth. This methodology allows the first finite element treatment of the technically important case of a resonator containing a sapphire element with a cylindrically aligned c axis. Second order trial functions together with quadrilateral elements are adopted in the calculations. The method was validated through comparisons with the analytical solutions for the hollow metal cavity and a coaxial cavity, as well as through measurements on a shielded sapphire resonator.

  13. Trapping of Microparticles in Cylindrical Standing Wave Fields

    NASA Astrophysics Data System (ADS)

    Yang, Jeongwon; Hwang, Haerang; Bae, Young Min; Kim, Moojoon; Ha, Kanglyeol

    2013-07-01

    In this study, in order to determine the positions where microparticles are trapped in a cylindrical standing wave field, we derived equations giving the radiation force and potential energy distribution. Then, the trapped pattern and its variation with time in a hollow cylindrical transducer were simulated. The simulation results showed that polystyrene particles moved to and aggregated near positions corresponding to pressure nodes, which were estimated from the derived equations. These were confirmed by measurement. In addition, it was demonstrated that biological particles of the green algae chlorella show similar trapping phenomena to polystyrene particles.

  14. Experiments on cylindrically converging blast waves in atmospheric air

    NASA Astrophysics Data System (ADS)

    Matsuo, Hideo; Nakamura, Yuichi

    1980-06-01

    Cylindrically converging blast waves have been produced in normal atmospheric conditions by the detonation of the explosives, pentaerythritoltetranitrate, (PETN), over cylindrical surfaces. The shocks generated in this way are so strong that the fronts propagating through the air become luminous of themselves. The production and the propagation of the shocks have been monitored with a framing camera and a streak camera, and the time-space relations of the shock propagations have been determined using an electrical ionization probing system. The results have shown that the trajectory of the shock fronts near the axis of the cylinder can be approximately represented by the Guderley's formula.

  15. Real-time wideband cylindrical holographic surveillance system

    DOEpatents

    Sheen, D.M.; McMakin, D.L.; Hall, T.E.; Severtsen, R.H.

    1999-01-12

    A wideband holographic cylindrical surveillance system is disclosed including a transceiver for generating a plurality of electromagnetic waves; antenna for transmitting the electromagnetic waves toward a target at a plurality of predetermined positions in space; the transceiver also receiving and converting electromagnetic waves reflected from the target to electrical signals at a plurality of predetermined positions in space; a computer for processing the electrical signals to obtain signals corresponding to a holographic reconstruction of the target; and a display for displaying the processed information to determine nature of the target. The computer has instructions to apply Fast Fourier Transforms and obtain a three dimensional cylindrical image. 13 figs.

  16. Real-time wideband cylindrical holographic surveillance system

    DOEpatents

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.; Severtsen, Ronald H.

    1999-01-01

    A wideband holographic cylindrical surveillance system including a transceiver for generating a plurality of electromagnetic waves; antenna for transmitting the electromagnetic waves toward a target at a plurality of predetermined positions in space; the transceiver also receiving and converting electromagnetic waves reflected from the target to electrical signals at a plurality of predetermined positions in space; a computer for processing the electrical signals to obtain signals corresponding to a holographic reconstruction of the target; and a display for displaying the processed information to determine nature of the target. The computer has instructions to apply Fast Fourier Transforms and obtain a three dimensional cylindrical image.

  17. Morphological instability of whiskers, pores, and tubules

    NASA Astrophysics Data System (ADS)

    Kirill, Dimitri Jay

    1999-11-01

    A thin, stressed solid cylinder, a whisker, is subject to mass transport by curvature and elastic-stress-driven surface diffusion. The stability of the cylindrical surface is examined using linear stability theory. It is found that the applied stress leads to a greater range of unstable wavenumbers, and hence is destabilizing. The presence of elastic strains can excite non-axisymmetric modes, which, under certain conditions, are preferred and can give rise to helical surfaces. In addition, asymptotic formulas for growth rate in the limit of long and short wavelengths are found. A possible experiment is proposed which, if undertaken, should reveal the helical instability. The linear stability analysis is then extended to the case of cylindrical pore channels and hollow cylindrical tubules. In both cases, results similar to the whisker are found---increased applied stress leads to a greater range of unstable wavenumbers. For both the pore and tubule geometries, the dominant modes are axisymmetric for any value of applied stress; this contrasts with the solid whisker results. Since the tubule geometry consists of an inner and outer surface, there is a phase relationship between the two surface perturbations. The most dangerous eigenmode can exhibit either in-phase (sinuous) or 180° out-of-phase (varicose) perturbations, depending on the value of applied stress. Furthermore, there is a critical value of applied stress below which the most dangerous mode is varicose, and above which it is sinuous. Lastly, asymptotic formulas for growth rate are obtained in the limit of a thin-walled tubule. These results compare favorably to work done on stressed lamellar composites.

  18. Challenges in Fabrication of Mesoporous Carbon Films with Ordered Cylindrical Pores via Phenolic Oligomer Self-Assembly with Triblock Copolymers

    SciTech Connect

    Song, Lingyan; Feng, Dan; Fredin, Nathaniel J.; Yager, Kevin G.; Jones, Ronald L.; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D.

    2010-06-22

    Mesoporous phenol formaldehyde (PF) polymer resin and carbon films are prepared by a solution self-assembly of PF oligomers with amphiphilic triblock copolymers. After thermopolymerization of the PF to cross-link the network, the films show an ordered morphology as determined by X-ray diffraction and grazing incidence small-angle X-ray scattering (GISAXS). Our results show that the amphiphilic triblock copolymer template greatly influences the stability of the final porous mesostructures. The pyrolysis of the two-dimensional (2-D) hexagonal films with p6mm symmetry templated by Pluronic F127 yields a disordered porous structure following the template removal. Conversely, films templated by Pluronic P123 can exhibit well-ordered cylindrical pores after the template removal, but the solution composition range to yield ordered cylindrical mesopores is significantly reduced (nearly 70%) for thin films in comparison to bulk powders. We propose two dominant difficulties in fabricating well-ordered cylindrical mesopores in films: first, the stress from contraction during the pyrolysis can lead to a collapse of the mesostructure if the wall thickness is insufficient, and second, the surface wetting behavior in thin films leads to a small compositional range.

  19. Patient Admission Preferences and Perceptions

    PubMed Central

    Wu, Clayton; Melnikow, Joy; Dinh, Tu; Holmes, James F.; Gaona, Samuel D.; Bottyan, Thomas; Paterniti, Debora; Nishijima, Daniel K.

    2015-01-01

    Introduction Understanding patient perceptions and preferences of hospital care is important to improve patients’ hospitalization experiences and satisfaction. The objective of this study was to investigate patient preferences and perceptions of hospital care, specifically differences between intensive care unit (ICU) and hospital floor admissions. Methods This was a cross-sectional survey of emergency department (ED) patients who were presented with a hypothetical scenario of a patient with mild traumatic brain injury (TBI). We surveyed their preferences and perceptions of hospital care related to this scenario. A closed-ended questionnaire provided quantitative data on patient preferences and perceptions of hospital care and an open-ended questionnaire evaluated factors that may not have been captured with the closed-ended questionnaire. Results Out of 302 study patients, the ability for family and friends to visit (83%), nurse availability (80%), and physician availability (79%) were the factors most commonly rated “very important,” while the cost of hospitalization (62%) and length of hospitalization (59%) were the factors least commonly rated “very important.” When asked to choose between the ICU and the floor if they were the patient in the scenario, 33 patients (10.9%) choose the ICU, 133 chose the floor (44.0%), and 136 (45.0%) had no preference. Conclusion Based on a hypothetical scenario of mild TBI, the majority of patients preferred admission to the floor or had no preference compared to admission to the ICU. Humanistic factors such as the availability of doctors and nurses and the ability to interact with family appear to have a greater priority than systematic factors of hospitalization, such as length and cost of hospitalization or length of time in the ED waiting for an in-patient bed. PMID:26587095

  20. The Allometry of Prey Preferences

    PubMed Central

    Kalinkat, Gregor; Rall, Björn Christian; Vucic-Pestic, Olivera; Brose, Ulrich

    2011-01-01

    The distribution of weak and strong non-linear feeding interactions (i.e., functional responses) across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles) simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses) as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems. PMID:21998724

  1. Exact Faraday rotation in the cylindrical Einstein-Maxwell waves

    SciTech Connect

    Arafah, M.R.; Fakioglu, S.; Halilsoy, M. )

    1990-07-15

    We obtain the exact behavior of the cross-polarized cylindrical Einstein-Maxwell waves that generalizes the well-known Einstein-Rosen waves. In the presence of the second mode of polarization the outgoing waves interact with the incoming ones to exhibit an analogous effect of the Faraday rotation.

  2. A circumferential crack in a cylindrical shell under tension.

    NASA Technical Reports Server (NTRS)

    Duncan-Fama, M. E.; Sanders, J. L., Jr.

    1972-01-01

    A closed cylindrical shell under uniform internal pressure has a slit around a portion of its circumference. Linear shallow shell theory predicts inverse square-root-type singularities in certain of the stresses at the crack tips. This paper reports the computed strength of these singularities for different values of a dimensionless parameter based on crack length, shell radius and shell thickness.

  3. Cylindrical surface profile and diameter measuring tool and method

    NASA Technical Reports Server (NTRS)

    Currie, James R. (Inventor); Kissel, Ralph R. (Inventor); Smith, Earnest C. (Inventor); Oliver, Charles E. (Inventor); Redmon, John W., Sr. (Inventor); Wallace, Charles C. (Inventor); Swanson, Charles P. (Inventor)

    1987-01-01

    A tool is shown having a cross beam assembly made of beams joined by a center box structure. The assembly is adapted to be mounted by brackets to the outer end of a cylindrical case. The center box structure has a vertical shaft rotatably mounted therein and extending beneath the assembly. Secured to the vertical shaft is a radius arm which is adapted to rotate with the shaft. On the longer end of the radius arm is a measuring tip which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm. An electric servomotor rotates the vertical shaft and an electronic resolver provides an electric signal representing the angle of rotation of the shaft. The electric signals are provided to a computer station which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle.

  4. Buckling of angle-ply laminated circular cylindrical shells

    NASA Technical Reports Server (NTRS)

    Hirano, Y.

    1979-01-01

    This note presents closed-form solutions for axisymmetrical and axially unsymmetrical buckling of angle-ply laminated circular cylindrical shells under axial compression. The axisymmetrical and axially unsymmetrical buckling stress are found to be different from each other, and the best lamination angles which give the highest buckling stress are obtained.

  5. Radiation of electromagnetic waves by cylindrical ring antennas

    NASA Astrophysics Data System (ADS)

    Dubrovka, F. F.; Pantov, V. S.

    1991-05-01

    The radiation characteristics of cylindrical ring antennas are studied theoretically and experimentally. The internal and external boundary value problems of electrodynamics are solved using the variational method of partial regions and the Fourier transformation method, respectively. The adequacy of the theoretical model is demonstrated experimentally.

  6. Analysis of cylindrical Langmuir probe using experiment and different theories

    SciTech Connect

    Hassouba, M. A.; Galaly, A. R.; Rashed, U. M.

    2013-03-15

    Cylindrical probe data have been analyzed using different theories in order to determine some plasma parameters (electron temperature and electron and ion densities). Langmuir probe data are obtained in a cylindrical DC glow discharge in the positive column plasma at argon gas pressures varied from 0.5 to 6 Torr and at constant discharge current equal to 10 mA. The electron density has calculated from the electron current at the space potential and from Orbital Motion Limited (OML) collisionless theory. Ion density has obtained from the OML analysis of the ion saturation currents. In addition, the electron temperature has measured by three different methods using probe and electrons currents. The electron temperature T{sub e}, plasma density n{sub e}, and space potential V{sub s}, have been obtained from the measured single cylindrical probe I-V characteristic curves. The radial distribution of the electron temperature and plasma density along the glow discharge are measured and discussed. Using the collisionless theories by Langmuir cylindrical probe and up to several Torr argon gas pressures the differences between the values of electron temperature and electron and ion densities stay within reasonable error limits.

  7. Calibrated cylindrical Mach probe in a plasma wind tunnel

    SciTech Connect

    Zhang, X.; Dandurand, D.; Gray, T.; Brown, M. R.; Lukin, V. S.

    2011-03-15

    A simple cylindrical Mach probe is described along with an independent calibration procedure in a magnetized plasma wind tunnel. A particle orbit calculation corroborates our model. The probe operates in the weakly magnetized regime in which probe dimension and ion orbit are of the same scale. Analytical and simulation models are favorably compared with experimental calibration.

  8. Screen of cylindrical lenses produces stereoscopic television pictures

    NASA Technical Reports Server (NTRS)

    Nork, C. L.

    1966-01-01

    Stereoscopic television pictures are produced by placing a colorless, transparent screen of adjacent parallel cylindrical lenses before a raster from two synchronized TV cameras. Alternate frames from alternate cameras are displayed. The viewers sensory perception fuses the two images into one three-dimensional picture.

  9. Cylindrical millimeter-wave imaging technique and applications

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    2006-05-01

    The wideband microwave or millimeter-wave cylindrical imaging technique has been developed at Pacific Northwest National Laboratory (PNNL) for several applications including concealed weapon detection and automated body measurement for apparel fitting. This technique forms a fully-focused, diffraction-limited, three-dimensional image of the person or imaging target by scanning an inward-directed vertical array around the person or imaging target. The array is switched electronically to sequence across the array at high-speed, so that a full 360 degree mechanical scan over the cylindrical aperture can occur in 2-10 seconds. Wideband, coherent reflection data from each antenna position are recorded in a computer and subsequently reconstructed using an FFT-based image reconstruction algorithm developed at PNNL. The cylindrical scanning configuration is designed to optimize the illumination of the target and minimize non-returns due to specular reflection of the illumination away from the array. In this paper, simulated modeling data are used to explore imaging issues that affect the cylindrical imaging technique. Physical optics scattering simulations are used to model realistic returns from curved surfaces to determine the extent to which specular reflection affects the signal return and subsequent image reconstruction from these surfaces. This is a particularly important issue for the body measurement application. Also, an artifact in the imaging technique, referred to as "circular convolution aliasing" is discussed including methods to reduce or eliminate it. Numerous simulated and laboratory measured imaging results are presented.

  10. Electron beam current in high power cylindrical diode

    SciTech Connect

    Roy, Amitava; Menon, R.; Mitra, S.; Sharma, Vishnu; Singh, S. K.; Nagesh, K. V.; Chakravarthy, D. P.

    2010-01-15

    Intense electron beam generation studies were carried out in high power cylindrical diode to investigate the effect of the accelerating gap and diode voltage on the electron beam current. The diode voltage has been varied from 130 to 356 kV, whereas the current density has been varied from 87 to 391 A/cm{sup 2} with 100 ns pulse duration. The experimentally obtained electron beam current in the cylindrical diode has been compared with the Langmuir-Blodgett law. It was found that the diode current can be explained by a model of anode and cathode plasma expanding toward each other. However, the diode voltage and current do not follow the bipolar space-charge limited flow model. It was also found that initially only a part of the cathode take part in the emission process. The plasma expands at 4.2 cm/mus for 1.7 cm anode-cathode gap and the plasma velocity decreases for smaller gaps. The electrode plasma expansion velocity of the cylindrical diode is much smaller as compared with the planar diode for the same accelerating gap and diode voltage. Therefore, much higher voltage can be obtained for the cylindrical diodes as compared with the planar diodes for the same accelerating gap.

  11. Optical scanning apparatus for indicia imprinted about a cylindrical axis

    DOEpatents

    Villarreal, Richard A.

    1987-01-01

    An optical scanner employed in a radioactive environment for reading indicia imprinted about a cylindrical surface of an article by means of an optical system including metallic reflective and mirror surfaces resistant to degradation and discoloration otherwise imparted to glass surfaces exposed to radiation.

  12. Cylindrical surface profile and diameter measuring tool and method

    NASA Technical Reports Server (NTRS)

    Currie, James R. (Inventor); Kissel, Ralph R. (Inventor); Oliver, Charles E. (Inventor); Smith, Earnest C. (Inventor); Redmon, John W. (Inventor); Wallace, Charles C. (Inventor); Swanson, Charles P. (Inventor)

    1989-01-01

    A tool is shown having a cross beam assembly (15) made of beams (18, 19, 20, 21) joined by a center box structure (23). The assembly (15) is adapted to be mounted by brackets (16) to the outer end of a cylindrical case (11). The center box structure (23) has a vertical shaft (25) rotatably mounted therein and extending beneath the assembly (15). Secured to the vertical shaft (25) is a radius arm (28) which is adapted to rotate with shaft (25). On the longer end of the radius arm (28) is a measuring tip (30) which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm (28). An electric servomotor (49) rotates the vertical shaft (25) and an electronic resolver (61) provides an electric signal representing the angle of rotation of the shaft (25). The electric signals are provided to a computer station (73) which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle.

  13. Hypersonic, nonequilibrium flow over a cylindrically blunted 6 deg wedge

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.

    1993-01-01

    The numerical simulation of hypersonic flow in chemical nonequilibrium over cylindrically blunted 6 degree wedge is described. The simulation was executed on a Cray C-90 with Program LAURA 92-vl. Code setup procedures and sample results, including grid refinement studies and variations of species number are discussed. This simulation relates to a study of wing leading edge heating on transatmospheric vehicles.

  14. Static Solutions of Einstein's Equations with Cylindrical Symmetry

    ERIC Educational Resources Information Center

    Trendafilova, C. S.; Fulling, S. A.

    2011-01-01

    In analogy with the standard derivation of the Schwarzschild solution, we find all static, cylindrically symmetric solutions of the Einstein field equations for vacuum. These include not only the well-known cone solution, which is locally flat, but others in which the metric coefficients are powers of the radial coordinate and the spacetime is…

  15. Hypersonic Magneto-Fluid-Dynamic Compression in Cylindrical Inlet

    NASA Technical Reports Server (NTRS)

    Shang, Joseph S.; Chang, Chau-Lyan

    2007-01-01

    Hypersonic magneto-fluid-dynamic interaction has been successfully performed as a virtual leading-edge strake and a virtual cowl of a cylindrical inlet. In a side-by-side experimental and computational study, the magnitude of the induced compression was found to be depended on configuration and electrode placement. To better understand the interacting phenomenon the present investigation is focused on a direct current discharge at the leading edge of a cylindrical inlet for which validating experimental data is available. The present computational result is obtained by solving the magneto-fluid-dynamics equations at the low magnetic Reynolds number limit and using a nonequilibrium weakly ionized gas model based on the drift-diffusion theory. The numerical simulation provides a detailed description of the intriguing physics. After validation with experimental measurements, the computed results further quantify the effectiveness of a magnet-fluid-dynamic compression for a hypersonic cylindrical inlet. At a minuscule power input to a direct current surface discharge of 8.14 watts per square centimeter of electrode area produces an additional compression of 6.7 percent for a constant cross-section cylindrical inlet.

  16. The Volume of a Torus Using Cylindrical and Spherical Coordinates

    ERIC Educational Resources Information Center

    Farmer, Jim

    2005-01-01

    The author of this article, while recently working through some problem sets on determining volumes by triple integrals in cylindrical and spherical coordinate systems, realized that, although the textbook he was using included many interesting problems involving spheres, cylinders and cones and the increasingly complex solids that arose from the…

  17. Optical nonuniformities in nuclear-pumped cylindrical lasers

    SciTech Connect

    Mat'ev, V Yu; Borovkov, V V; Mel'nikov, S P

    2000-03-31

    The optical nonuniformities, formed as a result of the effect of the inhomogeneous energy deposition by the fission fragments irradiating the laser-active gas from thin uranium-containing layers, were calculated for cylindrical nuclear-pumped gas lasers. The results of the calculations agree with the experiment. (active media. lasers)

  18. 15. CYLINDRICAL FISH SCALER Remnants of the wire screen remain, ...

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

    15. CYLINDRICAL FISH SCALER Remnants of the wire screen remain, through which the fish tumbled as the cylinder revolved. Note geared ring around cylinder, and the small drive shaft by which it was driven. - Hovden Cannery, 886 Cannery Row, Monterey, Monterey County, CA

  19. On Ideal Stability of Cylindrical Localized Interchange Modes

    SciTech Connect

    Umansky, M V

    2007-05-15

    Stability of cylindrical localized ideal pressure-driven interchange plasma modes is revisited. Converting the underlying eigenvalue problem into the form of the Schroedinger equation gives a new simple way of deriving the Suydam stability criterion and calculating the growth rates of unstable modes. Near the marginal stability limit the growth rate is exponentially small and the mode has a double-peak structure.

  20. Double focusing ion mass spectrometer of cylindrical symmetry

    NASA Technical Reports Server (NTRS)

    Coplan, M. A.; Moore, J. H.; Hoffman, R. A.

    1984-01-01

    A mass spectrometer consisting of an electric sector followed by a magnetic sector is described. The geometry is a cylindrically symmetric generalization of the Mattauch-Herzog spectrometer (1934). With its large annular entrance aperture and a position-sensitive detector, the instrument provides a large geometric factor and 100-percent duty factor, making it appropriate for spacecraft experiments.

  1. QUASI-PML FOR WAVES IN CYLINDRICAL COORDINATES. (R825225)

    EPA Science Inventory

    We prove that the straightforward extension of Berenger's original perfectly matched layer (PML) is not reflectionless at a cylindrical interface in the continuum limit. A quasi-PLM is developed as an absorbing boundary condition (ABC) for the finite-difference time-domain method...

  2. Dynamics of a Liquid Dielectric Attracted by a Cylindrical Capacitor

    ERIC Educational Resources Information Center

    Nardi, Rafael; Lemos, Nivaldo A.

    2007-01-01

    The dynamics of a liquid dielectric attracted by a vertical cylindrical capacitor are studied. Contrary to what might be expected from the standard calculation of the force exerted by the capacitor, the motion of the dielectric is different depending on whether the charge or the voltage of the capacitor is held constant. The problem turns out to…

  3. Efficient Generation of Truncated Bessel Beams using Cylindrical Waveguides

    NASA Technical Reports Server (NTRS)

    Ilchenko, Vladimir S.; Mohageg, Makan; Savchenkov, Anatoliy A.; Matsko, Andrey B.; Maleki, Lute

    2007-01-01

    In this paper we address efficient conversion between a Gaussian beam (a truncated plane wave) and a truncated Bessel beam of agiven order, using cylindrical optical waveguides and whispering gallery mode resonators. Utilizing a generator based on waveguides combined with whispering gallery mode resonators, we have realized Bessel beams of the order of 200 with a conversion efficiency exceeding 10 %.

  4. Diblock copolymers in bulk and in thin films: Morphology and kinetics

    NASA Astrophysics Data System (ADS)

    Podariu, Iulia Anca

    In this thesis I numerically study the phase diagram and kinetics of a diblock copolymers melt in both bulk and thin films in the strong segregation limit. I probe various values of the volume fraction, f, of the shorter block of the copolymer chains, spanning the bulk phase diagram for the diblock copolymers from a spherical body-centered cubic (BCC) phase to a hexagonally packed cylindrical (HCP) phase, to a bicontinuous gyroid phase (G), to finally a lamellar phase(L). Finite size and wetting properties of the substrate modify the film morphology by shifting the effective value of the composition in the film. For neutral substrates, the film morphology is shifted toward a smaller relative composition f, while for substrates which prefer the longer blocks of the copolymers, the film morphology is shifted toward a large value of f. A dramatic change in thin film morphology takes place for a small change in external parameters if one chooses the composition f to be at the borderline between two different bulk phases. The next question addressed is that of the control over the thin film structure in the case of a symmetric diblock copolymer films with a thickness smaller than the bulk equilibrium period. These films are cast on either flat or corrugated substrates. The results show that the formation of uniformly sized lateral domains that appear randomly on a flat surface can be controlled by using topographically patterned substrates. Control of lateral pattern fails if the distance between steps is smaller than the lamellar wavelength or the lateral size of the corrugation is larger than the bulk lamellar wavelength. For thin block copolymer (BCP) films on a homogeneous substrate, a fast domain growth exponent has recently been observed in experiments. I have carried out numerical simulations of ordering and domain growth in a two-dimensional system of BCP melts. The model calculations explicitly include viscous, hydrodynamic flow and provide a scaling

  5. Student selection and preference types.

    PubMed

    Gaskey, N J

    1982-02-01

    The use of paper and pencil tests for the selection of candidates and to identify individual differences should be approached cautiously because the interpretations of the tests can be very subjective. Although personal preferences do tend to become more stable as we grow older, they may vary from one day to the next. No one is an absolute extrovert or introvert; we all have tendencies toward one or the other depending on the particular situation and the mitigating circumstances. The preference type indicator is not recommended for use in selecting candidates for entrance into a nurse anesthesia program; but, rather, to make members of the department aware of the similarities and differences among people. It is helpful in making individuals aware of the other person's preferences. It is also useful in making them aware of the need to examine their own areas of weakness and to improve them before attempting to change someone else. PMID:7072461

  6. [Ovipositional preference of Grapholitha molesta].

    PubMed

    Gong, Qing-Tao; Li, Su-Hong; Zhang, Kun-Peng; Wu, Hai-Bin; Liu, Wei; Zhang, Xue-Ping; Sun, Rui-Hong

    2014-09-01

    In order to gain better understanding of the oviposition preference of Grapholitha molesta, we studied the ovipositional preference on different host fruit leaves, different parts of peach bran- ches and different varieties of peach in simulated outdoor conditions. The adult ovipositional preference on the host fruit leaves was in descending order, i. e. peach > cherry > apple > plum > pear > crabapple > apricot, and 33.5% of eggs were laid on the peach leaves with the average number of egg on one peach leaf being 8.3. There were differences in egg distribution on both sides of the leaves in different hosts. The number of egg laid on the positive surface was more than on the reverse surface of apple and crabapple leaves, and vice versus for peach, plum, pear and apricot leaves, and 3.3 times more eggs were laid on the reverse surface of peach leaves than on the positive surface. The egg distribution had no significant difference on both sides of cherry leaves. The adult ovipositional preference on peach branches was in descending order of leaf > stipule > petiole > branch. The leaves were the major ovipositonal places with 88.7% of total eggs on. 72.5% of eggs were laid on the 10 leaves near the top unexpanded leaflets, and the maximum number was on the 3rd leaf accounting for 9.3%, while only 1.1% of eggs were laid on the peach leaves after 25th. The ovipositional preference on different peach fruits was in descending order of nectarine > flat peach > prunus persica. The density and characteristics of the hair on host fruits and leaves were the primary factors affecting the ovipositional preference. PMID:25757320

  7. The value of customer preference

    SciTech Connect

    Herig, C.; Houston, A.

    1996-05-01

    Customer preference (CP), or green pricing, may be the financial hedge for electric supply industry integration of photovoltaics. CP is currently defined as a voluntary contribution for energy generated with renewable resources. Several utilities have examined the CP financing of renewables through experimental or implemented programs and market research. This paper first expands the concept of customer preference to include both voluntary and involuntary customer contributions. It then categorizes the features of existing and proposed CP programs. The connections between these features and market research and marketing strategies for new product development from a competitive industry are analyzed.

  8. Distributional preferences and competitive behavior☆

    PubMed Central

    Balafoutas, Loukas; Kerschbamer, Rudolf; Sutter, Matthias

    2012-01-01

    We study experimentally the relationship between distributional preferences and competitive behavior. We find that spiteful subjects react strongest to competitive pressure and win in a tournament significantly more often than efficiency-minded and inequality averse subjects. However, when given the choice between a tournament and a piece rate scheme, efficiency-minded subjects choose the tournament most often, while spiteful and inequality averse subjects avoid it. When controlling for distributional preferences, risk attitudes and past performance, the gender gap in the willingness to compete is no longer significant, indicating that gender-related variables explain why twice as many men as women self-select into competition. PMID:23576829

  9. An Interactive Point Kernel Program For Photon Dose Rate Prediction of Cylindrical Source/Shield Arrangements.

    Energy Science and Technology Software Center (ESTSC)

    1990-10-26

    Version 00 The program ZYLIND is an interactive point kernel program for photon dose rate prediction of a homogeneous cylindrical source shielded by cylindrical (radial) or plane (axial) layered shields.

  10. 4 CFR 2.6 - Veterans' preference.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 4 Accounts 1 2011-01-01 2011-01-01 false Veterans' preference. 2.6 Section 2.6 Accounts GOVERNMENT ACCOUNTABILITY OFFICE PERSONNEL SYSTEM PURPOSE AND GENERAL PROVISION § 2.6 Veterans' preference. (a) GAO will provide preference, for any individual who would be a preference eligible in the executive branch, in...

  11. 5 CFR 337.304 - Veterans' preference.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Veterans' preference. 337.304 Section 337... Alternative Rating and Selection Procedures § 337.304 Veterans' preference. In this subpart: (a) Veterans' preference must be applied as prescribed in 5 U.S.C. 3319(b) and (c)(2); (b) Veterans' preference points...

  12. 5 CFR 337.304 - Veterans' preference.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 1 2012-01-01 2012-01-01 false Veterans' preference. 337.304 Section 337... Alternative Rating and Selection Procedures § 337.304 Veterans' preference. In this subpart: (a) Veterans' preference must be applied as prescribed in 5 U.S.C. 3319(b) and (c)(2); (b) Veterans' preference points...

  13. 4 CFR 2.6 - Veterans' preference.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 4 Accounts 1 2013-01-01 2013-01-01 false Veterans' preference. 2.6 Section 2.6 Accounts GOVERNMENT ACCOUNTABILITY OFFICE PERSONNEL SYSTEM PURPOSE AND GENERAL PROVISION § 2.6 Veterans' preference. (a) GAO will provide preference, for any individual who would be a preference eligible in the executive branch, in...

  14. 4 CFR 2.6 - Veterans' preference.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 4 Accounts 1 2014-01-01 2013-01-01 true Veterans' preference. 2.6 Section 2.6 Accounts GOVERNMENT ACCOUNTABILITY OFFICE PERSONNEL SYSTEM PURPOSE AND GENERAL PROVISION § 2.6 Veterans' preference. (a) GAO will provide preference, for any individual who would be a preference eligible in the executive branch, in...

  15. 5 CFR 337.304 - Veterans' preference.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 1 2014-01-01 2014-01-01 false Veterans' preference. 337.304 Section 337... Alternative Rating and Selection Procedures § 337.304 Veterans' preference. In this subpart: (a) Veterans' preference must be applied as prescribed in 5 U.S.C. 3319(b) and (c)(2); (b) Veterans' preference points...

  16. 5 CFR 337.304 - Veterans' preference.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Veterans' preference. 337.304 Section 337... Alternative Rating and Selection Procedures § 337.304 Veterans' preference. In this subpart: (a) Veterans' preference must be applied as prescribed in 5 U.S.C. 3319(b) and (c)(2); (b) Veterans' preference points...

  17. 5 CFR 337.304 - Veterans' preference.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 1 2013-01-01 2013-01-01 false Veterans' preference. 337.304 Section 337... Alternative Rating and Selection Procedures § 337.304 Veterans' preference. In this subpart: (a) Veterans' preference must be applied as prescribed in 5 U.S.C. 3319(b) and (c)(2); (b) Veterans' preference points...

  18. 4 CFR 2.6 - Veterans' preference.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 4 Accounts 1 2012-01-01 2012-01-01 false Veterans' preference. 2.6 Section 2.6 Accounts GOVERNMENT ACCOUNTABILITY OFFICE PERSONNEL SYSTEM PURPOSE AND GENERAL PROVISION § 2.6 Veterans' preference. (a) GAO will provide preference, for any individual who would be a preference eligible in the executive branch, in...

  19. Preference Reversal in Multiattribute Choice

    ERIC Educational Resources Information Center

    Tsetsos, Konstantinos; Usher, Marius; Chater, Nick

    2010-01-01

    A central puzzle for theories of choice is that people's preferences between options can be reversed by the presence of decoy options (that are not chosen) or by the presence of other irrelevant options added to the choice set. Three types of reversal effect reported in the decision-making literature, the attraction, compromise, and similarity…

  20. Student Teachers' Classroom Management Preferences.

    ERIC Educational Resources Information Center

    Osborne, John W.; Boisvert, Gloria

    1989-01-01

    Investigated student teachers' preferences for several methods of classroom management. Fourth-year education students (N=70) were presented with four typical classroom problem behavior scenarios and were offered a choice of four approaches to manage problem. Results revealed that subjects strongly favored humanistic approaches to classroom…

  1. Cortisol shifts financial risk preferences.

    PubMed

    Kandasamy, Narayanan; Hardy, Ben; Page, Lionel; Schaffner, Markus; Graggaber, Johann; Powlson, Andrew S; Fletcher, Paul C; Gurnell, Mark; Coates, John

    2014-03-01

    Risk taking is central to human activity. Consequently, it lies at the focal point of behavioral sciences such as neuroscience, economics, and finance. Many influential models from these sciences assume that financial risk preferences form a stable trait. Is this assumption justified and, if not, what causes the appetite for risk to fluctuate? We have previously found that traders experience a sustained increase in the stress hormone cortisol when the amount of uncertainty, in the form of market volatility, increases. Here we ask whether these elevated cortisol levels shift risk preferences. Using a double-blind, placebo-controlled, cross-over protocol we raised cortisol levels in volunteers over 8 d to the same extent previously observed in traders. We then tested for the utility and probability weighting functions underlying their risk taking and found that participants became more risk-averse. We also observed that the weighting of probabilities became more distorted among men relative to women. These results suggest that risk preferences are highly dynamic. Specifically, the stress response calibrates risk taking to our circumstances, reducing it in times of prolonged uncertainty, such as a financial crisis. Physiology-induced shifts in risk preferences may thus be an underappreciated cause of market instability. PMID:24550472

  2. Bad Arguments Defending Racial Preference

    ERIC Educational Resources Information Center

    Cohen, Carl

    2008-01-01

    Professor Cohen describes the arduous path to the passage of Proposition 2 in Michigan in 2006. In considering the reasons for its victory, he shows how claims (sometimes well-intended) "for" preferences rest on truly bad arguments. (Contains 8 footnotes.)

  3. Parent Preference Study. Final Report.

    ERIC Educational Resources Information Center

    Baratz-Snowden, Joan; And Others

    A national survey of parents of school aged Asian, Puerto Rican, Mexican American, and Cuban students was conducted to examine what educational preferences language minority parents have regarding the role of English and non-English (home) language in the instructional process. A second purpose of the survey was to determine what factors are…

  4. Ethnicity and Children's TV Preferences.

    ERIC Educational Resources Information Center

    Eastman, Harvey A.; Liss, Marsha B.

    1980-01-01

    A survey of California intermediate-grade children revealed that Anglo and Hispanic children showed a strong preference for action/adventure shows, while Black children chose situation comedies at more than twice the rate of the other ethnic groups. Other differences were observed between ethnic groups and between sexes within ethnic groups. (GT)

  5. Personality Preferences of Outdoor Participants.

    ERIC Educational Resources Information Center

    Cashel, Christine; Montgomery, Diane; Lane, Suzie

    A study investigated the personality type preferences of people who voluntarily chose to participate in a structured, field-based, outdoor education program. The Myers-Briggs Type Indicator (MBTI) was administered to 87 participants prior to beginning a 10-day Wilderness Education Association outdoor leadership trip. Participants were 18-46 years…

  6. A Method to Calculate the Surface Tension of a Cylindrical Droplet

    ERIC Educational Resources Information Center

    Wang, Xiaosong; Zhu, Ruzeng

    2010-01-01

    The history of Laplace's equations for spherical and cylindrical droplets and the concept of dividing surface in Gibbs' thermodynamic theory of capillary phenomena are briefly reviewed. The existing theories of surface tensions of cylindrical droplets are briefly reviewed too. For cylindrical droplets, a new method to calculate the radius and the…

  7. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles

    NASA Astrophysics Data System (ADS)

    Qiu, Huibin; Hudson, Zachary M.; Winnik, Mitchell A.; Manners, Ian

    2015-03-01

    Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials.

  8. Precession of cylindrical dust particles in the plasma sheath

    SciTech Connect

    Banu, N.; Ticoş, C. M.

    2015-10-15

    The vertical precession of cylindrical dust particles levitated in the sheath of an rf plasma is experimentally investigated. Typically, the dust particles have two equilibrium positions depending on the orientation of their longitudinal axis: horizontal and vertical. A transition between these two states is induced by rapidly increasing the neutral gas pressure in the plasma chamber. During this transition, the cylindrical dust particles make an angle with the horizontal and rotate about their center of mass. The rotation speed increases as the dust rods aligned with the vertical axis. All dust particles will eventually end up in the vertical state while spinning fast about their longitudinal axis. Dust-dust interaction and the attracting ion wakes are possible mechanisms for inducing the observed dust precession.

  9. Magnetically induced cylindrical stress waves in a thermoelastic conductor

    NASA Technical Reports Server (NTRS)

    Chian, C. T.; Moon, F. C.

    1981-01-01

    The problem of stress wave generation in a linear thermoelastic solid by a pulsed magnetic field is investigated both analytically and experimentally for a cylindrically symmetric conducting solid. A dynamic response analysis is developed to correlate magnetic, thermal, and stress fields in the solid with the time history of the electric current. In the experiment, a transient magnetic field was applied normal to a large conducting plate with a circular hole. Initially the field was confined to the interior of the circular hole. The field was generated by discharging a large capacitor bank through a solenoidal coil. The plane-stress cylindrical stress waves are 1-D in nature. The relative effects of the magnetic body force and thermoelastic stresses, both generated by the electromagnetic field, are assessed.

  10. Support structure for a prestressed cylindrical pressure vessel

    SciTech Connect

    Schoening, J.; Schwiers, H.-G.

    1984-10-02

    A support structure for a nuclear power station having a prestressed cylindrical vessel comprising an annular ring of supports on a support wall and foundation wherein the prestressed cylindrical vessel rests on the ring of supports is disclosed. The supports, through their defined distances from each other, provide a constant cooling flow of the supports and a constant temperature over the entire operating period of the power station. This results in supports that are maintenance-free. The supports are constructed of plastic washers with steel inserts and are of sufficient height such that in the case of earthquakes, maximum vibrations of the reinforced concrete pressure vessel may be absorbed within an accurately set terminal boundary of the annular support wall.

  11. Thermal contact conductance for cylindrical and spherical contacts

    NASA Astrophysics Data System (ADS)

    Sunil Kumar, S.; Abilash, P. M.; Ramamurthi, K.

    A prediction methodology based on Monte-Carlo simulation model, developed for flat conforming surfaces in contact, is modified and extended to predict contact conductance between curvilinear surfaces like cylinders and spheres. Experiments are also conducted in vacuum for the measurement of contact conductance between stainless steel and aluminium cylindrical contacts and stainless steel spherical contacts over a range of contact pressures. The contact conductance between cylindrical and spherical bodies is, in general, about an order of magnitude lower than for flat surfaces in contact. Increase of surface roughness and decrease in contact pressure lowers the contact conductance. However, the influence of these parameters is larger than those obtained for flat surfaces. The prediction for different parametric conditions agree closely with those measured in the experiments.

  12. Reflection of solar radiation by a cylindrical cloud

    NASA Technical Reports Server (NTRS)

    Smith, G. L.

    1989-01-01

    Potential applications of an analytic method for computing the solar radiation reflected by a cylindrical cloud are discussed, including studies of radiative transfer within finite clouds and evaluations of these effects on other clouds and on remote sensing problems involving finite clouds. The pattern of reflected sunlight from a cylindrical cloud as seen at a large distance has been considered and described by the bidirectional function method for finite cloud analysis, as previously studied theoretically for plane-parallel atmospheres by McKee and Cox (1974); Schmetz and Raschke (1981); and Stuhlmann et al. (1985). However, the lack of three-dimensional radiative transfer solutions for anisotropic scattering media have hampered theoretical investigations of bidirectional functions for finite clouds. The present approach permits expression of the directional variation of the radiation field as a spherical harmonic series to any desired degree and order.

  13. Generating a cylindrical vector beam interferometrically for ellipsometric measurement

    NASA Astrophysics Data System (ADS)

    Chen, Jing-Heng; Chang, Ruey-Shyan; Han, Chien-Yuan

    2016-02-01

    Cylindrical vector beams have been widely used in material processing, lithography, optical trapping and manipulating. However, few works discussed their application in polarization metrology. A cylindrical vector beam generated by a concrete interferometer setup is employed to determine the ellipsometric parameters of thin films, which was discussed in this work. A TEM01 mode beam was applied as the light source impinging into a modified Michelson interferometer with contiguous optical elements. The mode of light beam was transformed and the polarization states were coordinated with the optical configuration that made the output beam a doughnut-shaped axially symmetric polarized beam. In addition, the output beam plays the same role as rotating polarization element configuration of an ellipsometer. However, the polarization modulation was in spatial domain instead of temporal domain. By making use of this configuration, ellipsometric parameters of thin films were deduced and the results were very close to theoretical values.

  14. Flow-induced vibration of an array of cylindrical pendulums

    NASA Astrophysics Data System (ADS)

    Kim, Junyoung; Kim, Hyeonseong; Kim, Daegyoum

    2015-11-01

    We investigated experimentally self-excited vibration of an array of cylindrical pendulums in a uniform flow in order to find its potential application to energy harvesting. A cylindrical pendulum is fixed to a rigid upper plate via a thin elastic sheet so that it can swing perpendicularly to the free stream. Although this type of model has been studied for electrical energy generation, few studies have been conducted in order to understand the detailed physics of fluid-structure interaction. In this study, the flow pattern and dynamics of pendulums were examined by varying distance among the pendulums, free-stream fluid velocity, density ratio of the fluid and the pendulums. The interaction of an upstream bluff body and pendulums was also considered to investigate how the wake of the bluff body affects the oscillations of cylinders. With this experimental setup, the pendulums show various patterns such as stationary mode and out-of-phase oscillation mode.

  15. Nonlinear dynamo action in a precessing cylindrical container.

    PubMed

    Nore, C; Léorat, J; Guermond, J-L; Luddens, F

    2011-07-01

    It is numerically demonstrated by means of a magnetohydrodynamics code that precession can trigger the dynamo effect in a cylindrical container. When the Reynolds number, based on the radius of the cylinder and its angular velocity, increases, the flow, which is initially centrosymmetric, loses its stability and bifurcates to a quasiperiodic motion. This unsteady and asymmetric flow is shown to be capable of sustaining dynamo action in the linear and nonlinear regimes. The magnetic field thus generated is unsteady and quadrupolar. These numerical evidences of dynamo action in a precessing cylindrical container may be useful for an experiment now planned at the Dresden sodium facility for dynamo and thermohydraulic studies in Germany. PMID:21867314

  16. Plasmon modes of circular cylindrical double-layer graphene.

    PubMed

    Zhao, Tao; Hu, Min; Zhong, Renbin; Chen, Xiaoxing; Zhang, Ping; Gong, Sen; Zhang, Chao; Liu, Shenggang

    2016-09-01

    In this paper, a theoretical investigation on plasmon modes in a circular cylindrical double-layer graphene structure is presented. Due to the interlayer electromagnetic interaction, there exist two branches of plasmon modes, the optical plasmon mode and the acoustic plasmon mode. The characteristics of these two modes, such as mode pattern, effective mode index and propagation loss, are analyzed. The modal behaviors can be effectively tuned by changing the distance between two graphene layers, the chemical potential of graphene and the permittivity of interlayer dielectric. Importantly, the breakup of tradeoff between mode confinement and propagation loss is discovered in the distance-dependent modal behavior, which originates from the unique dispersion properties of a double-layer graphene system. As a consequence, both strong mode confinement and longer propagation length can be achieved. Our results may provide good opportunities for developing applications based on graphene plasmonics in circular cylindrical structure. PMID:27607651

  17. Vortex-Driven Sound in a Cylindrical Cavity.

    NASA Astrophysics Data System (ADS)

    Flatau, Alison

    1990-08-01

    An experimental investigation of the flow induced acoustic response of a cylindrical cavity to variations in the stiffness of baffles that cause flow separation and vortex shedding is presented. Vortex shedding in the Space Shuttle solid rocket motors (SRMs) contributes to undesirable combustion instabilities or oscillations in the propellant burn rate that can introduce detrimental vibratory loads to the shuttle and its cargo, including astronauts who complain of a "rough ride." This study presents a cold flow simulation of the conditions that produce vortex shedding in the SRMs using a cylindrical cavity with annular protrusions or baffles extending from the cavity walls into the flow path. This work provides quantification of the frequency and relative amplitude of this flow induced acoustic response, called a hole tone response. Specifically investigated are the effects of variable baffle stiffness and of baffle resonance excitation on the acoustic frequency and amplitude of the cavity response.

  18. Slow viscous flow of two particles in a cylindrical tube

    NASA Astrophysics Data System (ADS)

    Yao, Xin; Wong, Teck Neng; Marcos, -

    2015-11-01

    The slow viscous flow around two particles in a cylindrical tube is obtained theoretically. We employ the Lamb's general solution based on spherical harmonics and cylindrical harmonics to solve the flow field around the particles and the flow within the tube, respectively. We compute the drag and torque coefficients of the particles which are dependent on the distance among the cylinder wall and the two particles. The hydrodynamic forces are also a function of particle velocities and background velocity. Our results are in agreement with the existing theory of a single particle traveling in the tube when the distance between the two particles increases. We found that particle-particle interactions can be neglected when the separation distance is three times larger than the sum of particles radii. Furthermore, such analysis can give us insights to understand the mechanisms of collision and aggregation of particles.

  19. Development of ultrasonic cylindrical cells for trapping of oil droplets

    NASA Astrophysics Data System (ADS)

    Andrade, M. A. B.; Junior, A. M. S.; Buiochi, F.; Adamowski, J. C.

    2012-05-01

    This work describes the development of ultrasonic cylindrical cells in the frequency range between 20 and 60 kHz for trapping of oil droplets in water. Each cell consists of a Langevin-type ultrasonic transducer and a cylindrical glass tube. The dimensions of each cell are determined by conducting simulations with the Finite Element Method (FEM). After determine the optimal dimensions, the cells were fabricated, and the pressure field predicted by the FEM were compared with that obtained experimentally by using a hydrophone (8103, Brüel & Kjaer). The comparison between both results shows good agreement when the transducer is excited with a low voltage signal. When the excitation voltage is increased, acoustic cavitation occurs and the signal measured by the hydrophone has many harmonics of the fundamental frequency, which are associated with the nonlinear radial oscillations of air microbubbles.

  20. Liquid inflow to a baffled cylindrical tank during weightlessness

    NASA Technical Reports Server (NTRS)

    Staskus, J. V.

    1972-01-01

    An experimental investigation was conducted in which the behavior of liquid inflow to a cylindrical tank containing inlet baffles was observed during weightlessness. A single tank radius (2 cm), inlet radius (0.2 cm), and liquid (ethanol)were used. The inlet end of the tank was hemispherical with a 30 deg convergent inlet. All the baffle configurations tested were cylindrically symmetric and mounted coaxially with the tank within the hemispherical end. Both stable and unstable inflow behavior were observed using each baffle. It was found that, depending on which of the baffles was used, the critical inflow velocity at which a transition to unstable inflow began was from 2.5 to 12 times greater than the corresponding velocity in an unbaffled tank.

  1. Sound Transmission through a Cylindrical Sandwich Shell with Honeycomb Core

    NASA Technical Reports Server (NTRS)

    Tang, Yvette Y.; Robinson, Jay H.; Silcox, Richard J.

    1996-01-01

    Sound transmission through an infinite cylindrical sandwich shell is studied in the context of the transmission of airborne sound into aircraft interiors. The cylindrical shell is immersed in fluid media and excited by an oblique incident plane sound wave. The internal and external fluids are different and there is uniform airflow in the external fluid medium. An explicit expression of transmission loss is derived in terms of modal impedance of the fluids and the shell. The results show the effects of (a) the incident angles of the plane wave; (b) the flight conditions of Mach number and altitude of the aircraft; (c) the ratios between the core thickness and the total thickness of the shell; and (d) the structural loss factors on the transmission loss. Comparisons of the transmission loss are made among different shell constructions and different shell theories.

  2. Precise DOA Estimation Using SAGE Algorithm with a Cylindrical Array

    NASA Astrophysics Data System (ADS)

    Takanashi, Masaki; Nishimura, Toshihiko; Ogawa, Yasutaka; Ohgane, Takeo

    A uniform circular array (UCA) is a well-known array configuration which can accomplish estimation of 360° field of view with identical accuracy. However, a UCA cannot estimate coherent signals because we cannot apply the SSP owing to the structure of UCA. Although a variety of studies on UCA in coherent multipath environments have been done, it is impossible to estimate the DOA of coherent signals with different incident polar angles. Then, we have proposed Root-MUSIC algorithm with a cylindrical array. However, the estimation performance is degraded when incident signals arrive with close polar angles. To solve this problem, in the letter, we propose to use SAGE algorithm with a cylindrical array. Here, we adopt a CLA Root-MUSIC for the initial estimation and decompose two-dimensional search to double one-dimensional search to reduce the calculation load. The results show that the proposal achieves high resolution with low complexity.

  3. Selective formation of turbulent structures in magnetized cylindrical plasmas

    SciTech Connect

    Kasuya, Naohiro; Itoh, Kimitaka; Yagi, Masatoshi; Itoh, Sanae-I

    2008-05-15

    The mechanism of nonlinear structural formation has been studied with a three-field reduced fluid model, which is extended to describe the resistive drift wave turbulence in magnetized cylindrical plasmas. In this model, ion-neutral collisions strongly stabilize the resistive drift wave, and the formed structure depends on the collision frequency. If the collision frequency is small, modulational coupling of unstable modes generates a zonal flow. On the other hand, if the collision frequency is large, a streamer, which is a localized vortex in the azimuthal direction, is formed. The structure is generated by nonlinear wave coupling and is sustained for a much longer duration than the drift wave oscillation period. This is a minimal model for analyzing the turbulent structural formation mechanism by mode coupling in cylindrical plasmas, and the competitive nature of structural formation is revealed. These turbulent structures affect particle transport.

  4. Selective decay in a long cylindrical geometry in SSX

    NASA Astrophysics Data System (ADS)

    Gray, T.; Brown, M.; Dandurand, D.; Zhang, X.

    2010-11-01

    A helical, minimum-energy relaxed plasma state has been observed in a long cylindrical volume. The cylinder is long enough (L/R = 13) so that the predicted minimum energy state is a close approximation to the infinite cylinder solution. The plasma is injected at v >=50 km/s by a coaxial magnetized plasma gun located at one end of the cylindrical volume. The relaxed state is rapidly attained in 1--2 axial Alfvén times after initiation of the plasma. Magnetic data is favorably compared with an analytical model. Magnetic data exhibits broadband fluctuations of the measured axial modes during the formation period. The broadband activity rapidly decays as the energy condenses into the lowest energy mode, which is in agreement to the minimum energy eigenstate of ∇xB = λB. Merging experiments are planned and additional data will be presented if available.

  5. Coupled domain wall oscillations in magnetic cylindrical nanowires

    SciTech Connect

    Murapaka, Chandrasekhar; Goolaup, S.; Purnama, I.; Lew, W. S.

    2015-02-07

    We report on transverse domain wall (DW) dynamics in two closely spaced cylindrical nanowires. The magnetostatically coupled DWs are shown to undergo an intrinsic oscillatory motion along the nanowire length in addition to their default rotational motion. In the absence of external forces, the amplitude of the DW oscillation is governed by the change in the frequency of the DW rotation. It is possible to sustain the DW oscillations by applying spin-polarized current to the nanowires to balance the repulsive magnetostatic coupling. The current density required to sustain the DW oscillation is found to be in the order of 10{sup 5 }A/cm{sup 2}. Morover, our analysis of the oscillation reveals that the DWs in cylindrical nanowires possess a finite mass.

  6. Inverse radiation problem in axisymmetric cylindrical scattering media

    NASA Astrophysics Data System (ADS)

    Menguc, M. P.; Manickavasagam, S.

    1993-09-01

    A semianalytical technique has been developed to solve the inverse radiation problem in absorbing and scattering cylindrical media. The radiative properties in the medium are allowed to vary radially. Isotropic, linearly anisotropic, and Rayleigh scattering phase functions are considered, and both the first- and second-order scattering of radiation are accounted for in the analysis. The angular radiosity distribution obtained from the solution of the forward problem is employed as input to the inverse analysis. A numerical inversion scheme is followed to determine the profiles of extinction coefficient and the single-scattering albedo. For an anisotropically scattering medium, the asymmetry factor is also recovered. It is shown that the method is simple and accurate, even though the inversion is limited to three- or four-layer media. This inversion procedure can easily be used in experiments to determine the effective radiative property distributions in cylindrical systems.

  7. Spinor Condensates on a Cylindrical Surface in Synthetic Gauge Fields.

    PubMed

    Ho, Tin-Lun; Huang, Biao

    2015-10-01

    We show that by modifying the setup of the recent experiment that creates a "Dirac string" one can engineer a quasi-2D spinor Bose-Einstein condensate on a cylindrical surface, with a synthetic magnetic field normal to the surface. Because of the muticonnectivity of the surface, there are two types of vortices (called A and B) with the same vorticity. This is very different from the planar case, which only has one kind of vortex for fixed circulation. As the strength of the synthetic gauge field increases, the ground states will form a necklace of alternating AB vortices surrounding the lateral midpoint of the cylinder, and will split into two A and B necklaces at higher synthetic gauge fields. The fact that even the basic vortex structure of a Bose-Einstein condensate is altered in a cylindrical surface implies that richer phenomena are in store for quantum gases in other curved surfaces. PMID:26550734

  8. Morphologies of poly(cyclohexadiene) diblock copolymers

    SciTech Connect

    Kumar, Rajeev; Mays, Jimmy; Sides, Scott; Goswami, Monojoy; Sumpter, Bobby G; Hong, Kunlun; Avgeropoulos, Apostolos; Russell, Thomas P; Gido, Samuel; Tsoukatos, Thodoris; Beyer, Fredrick

    2012-01-01

    Concerted experimental and theoretical investigations have been carried out to understand the micro-phase separation in diblock copolymer melts containing poly (1,3-cyclohexadiene), PCHD, as one of the constituents. In particular, we have studied diblock copolymer melts containing polystyrene (PS), polybutadiene (PB), and polyisoprene (PI) as the second block. We have systematically varied the ratio of 1,2- /1,4-microstructures of poly (1,3-cyclohexadiene) to tune the conformational asymmetry between the two blocks and characterized the effects of these changes on the morphologies using transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Our experimental investigations reveal that the melts of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing nearly equal fractions of each component and high percentage of 1,4-microstructures in the PCHD block form cylindrical rather than lamellar morphologies as expected in symmetric diblock copolymers. In contrast, the morphologies of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing PCHD block with higher 1,2-microstructure are found to be disordered at 110 C. The change in the morphological behavior is in good agreement with our numerical calculations using the random phase approximation and self-consistent field theory for conformationally asymmetric diblock copolymer melts. Also, the effects of composition fluctuations are studied by extending the Brazovskii-Leibler-Fredrickson-Helfand (J. Chem. Phys. 87, 697 (1987)) theory to conformationally asymmetric diblock copolymer melts. These results allow the understanding of the underlying self-assembly process that highlights the importance of the conformational asymmetry in tuning the morphologies in block copolymers.

  9. Four-Sector Cylindrical Radio-Frequency Ion Trap

    NASA Technical Reports Server (NTRS)

    Melbourne, Ruthann K.; Prestage, John D.; Maleki, Lutfollah

    1992-01-01

    Proposed linear radio-frequency ion trap consists of closed metal cylinder partitioned into four equal cylindrical-sector electrodes and two circular end electrodes. Features include relatively large ion-storage capacity and shielding against external fields. Used in frequency-standard laboratories to confine 199Hg+ ions electrodynamically in isolation from external environment. Similar to device described in "Linear Ion Trap for Atomic Clock" (NPO-17758).

  10. Depolarization of Light Scattered from Rough Cylindrical Surfaces

    NASA Astrophysics Data System (ADS)

    Aparicio, R.; Quintián, F. Perez; Rebollo, M. A.

    2008-04-01

    In this work we study the state of polarization of light scattered from rough cylindrical surfaces. The experimental results show that the amount of cross-polarized light at a particular observation angle is correlated with the roughness of the cylinders. We compare these results with those obtained using the Kirchhoff's vector theory and analyze if the differences can be modeled on multiple-scattering effects.

  11. Transition in electron transport in a cylindrical Hall thruster

    SciTech Connect

    Parker, J. B.; Raitses, Y.; Fisch, N. J.

    2010-08-30

    Through the use of high-speed camera and Langmuir probe measurements in a cylindrical Hall thruster, we report the discovery of a rotating spoke of increased plasma density and light emission which correlates with increased electron transport across the magnetic field. As cathode electron emission is increased, a sharp transition occurs where the spoke disappears and electron transport decreases. This suggests that a significant fraction of the electron current might be directed through the spoke.

  12. Transition in Electron Transport in a Cylindrical Hall Thruster

    SciTech Connect

    J.B. Parker, Y. Raitses, and N.J. Fisch

    2010-06-02

    Through the use of high-speed camera and Langmuir probe measurements in a cylindrical Hall thruster, we report the discovery of a rotating spoke of increased plasma density and light emission which correlates with increased electron transport across the magnetic field. As cathode electron emission is increased, a sharp transition occurs where the spoke disappears and electron transport decreases. This suggests that a significant fraction of the electron current might be directed through the spoke.

  13. Evolution of bulk strain solitons in cylindrical inhomogeneous shells

    SciTech Connect

    Shvartz, A. Samsonov, A.; Dreiden, G.; Semenova, I.

    2015-10-28

    Bulk strain solitary waves in nonlinearly elastic thin-walled cylindrical shells with variable geometrical and physical parameters are studied, and equation for the longitudinal strain component with the variable coefficients is derived. A conservative finite difference scheme is proposed, and the results of numerical simulation of the strain soliton evolution in a shell with the abrupt variations of cross section and physical properties of the material are presented.

  14. Nonstationary Mass Transfer Near the Surface of a Cylindrical Body

    NASA Astrophysics Data System (ADS)

    Rudobashta, S. P.; Kosheleva, M. K.; Kartashov, É. M.

    2015-11-01

    The problem of nonstationary diffusion of the target component to a phase that is external relative to the surface of a cylindrical body has been formulated and solved analytically. From the found solution the dependences have been obtained for calculating the instantaneous mass transfer coefficient and the phase-contact-time mean mass transfer coefficient, on the basis of which the process of extraction of technological pollutants from fibrous materials has been analyzed.

  15. Cylindrical cloaking at oblique incidence with optimized finite multilayer parameters.

    PubMed

    Zhang, Baile; Wu, Bae-Ian

    2010-08-15

    We propose multilayer cylindrical invisibility cloaks that are optimized for oblique incidences through a combination of analytic formalism of scattering and genetic optimization. We show that by using only four layers of homogeneous and anisotropic metamaterials without large values of constitutive parameters, the scattering for oblique incidences can be reduced by 2 orders. Although the optimization is done at a single incident angle, the cloak provides reduced scattering over a large range of incident angles. PMID:20717422

  16. Evaluation of direct-exchange areas for a cylindrical enclosure

    SciTech Connect

    Sika, J. )

    1991-11-01

    This paper reports on a method for calculating the radiative heat transfer direct-exchange areas for surface-to-surface, volume-to-surface, and volume-to-volume pairs of zones in axisymmetric cylindrical geometries. With this method the calculation of the direct-exchange areas can be transformed from the original four-, five-, and sixfold integrals in the defining relations to just single and/or double integrals. Gray gas with absorption coefficient K is assumed.

  17. Evolution of bulk strain solitons in cylindrical inhomogeneous shells

    NASA Astrophysics Data System (ADS)

    Shvartz, A.; Samsonov, A.; Dreiden, G.; Semenova, I.

    2015-10-01

    Bulk strain solitary waves in nonlinearly elastic thin-walled cylindrical shells with variable geometrical and physical parameters are studied, and equation for the longitudinal strain component with the variable coefficients is derived. A conservative finite difference scheme is proposed, and the results of numerical simulation of the strain soliton evolution in a shell with the abrupt variations of cross section and physical properties of the material are presented.

  18. Ideal internal kink modes in a differentially rotating cylindrical plasma

    SciTech Connect

    Mikhailovskii, A. B.; Lominadze, J. G.; Galvao, R. M. O.; Churikov, A. P.; Erokhin, N. N.; Pustovitov, V. D.; Konovalov, S. V.; Smolyakov, A. I.; Tsypin, V. S.

    2008-07-15

    The Velikhov effect leading to magnetorotational instability (MRI) is incorporated into the theory of ideal internal kink modes in a differentially rotating cylindrical plasma column. It is shown that this effect can play a stabilizing role for suitably organized plasma rotation profiles, leading to suppression of MHD (magnetohydrodynamic) instabilities in magnetic confinement systems. The role of this effect in the problem of the Suydam and the m = 1 internal kink modes is elucidated, where m is the poloidal mode number.

  19. Theory of semicollisional drift-interchange modes in cylindrical plasmas

    SciTech Connect

    Hahm, T.S.; Chen, L.

    1985-01-01

    Resistive interchange instabilities in cylindrical plasmas are studied, including the effects of electron diamagnetic drift, perpendicular resistivity, and plasma compression. The analyses are pertinent to the semicollisional regime where the effective ion gyro-radius is larger than the resistive layer width. Both analytical and numerical results show that the modes can be completely stabilized by the perpendicular plasma transport. Ion sound effects, meanwhile, are found to be negligible in the semicollisional regime.

  20. DNA barcoding to identify leaf preference of leafcutting bees

    PubMed Central

    2016-01-01

    Leafcutting bees (Megachile: Megachilidae) cut leaves from various trees, shrubs, wildflowers and grasses to partition and encase brood cells in hollow plant stems, decaying logs or in the ground. The identification of preferred plant species via morphological characters of the leaf fragments is challenging and direct observation of bees cutting leaves from certain plant species are difficult. As such, data are poor on leaf preference of leafcutting bees. In this study, I use DNA barcoding of the rcbL and ITS2 regions to identify and compare leaf preference of three Megachile bee species widespread in Toronto, Canada. Nests were opened and one leaf piece from one cell per nest of the native M. pugnata Say (N=45 leaf pieces), and the introduced M. rotundata Fabricius (N=64) and M. centuncularis (L.) (N=65) were analysed. From 174 individual DNA sequences, 54 plant species were identified. Preference by M. rotundata was most diverse (36 leaf species, H′=3.08, phylogenetic diversity (pd)=2.97), followed by M. centuncularis (23 species, H′=2.38, pd=1.51) then M. pugnata (18 species, H′=1.87, pd=1.22). Cluster analysis revealed significant overlap in leaf choice of M. rotundata and M. centuncularis. There was no significant preference for native leaves, and only M. centuncularis showed preference for leaves of woody plants over perennials. Interestingly, antimicrobial properties were present in all but six plants collected; all these were exotic plants and none were collected by the native bee, M. pugnata. These missing details in interpreting what bees need offers valuable information for conservation by accounting for necessary (and potentially limiting) nesting materials. PMID:27069650

  1. Cylindrical millimeter-wave imaging technique for concealed weapon detection

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    1998-03-01

    A novel cylindrical millimeter-wave imaging technique has been developed at the Pacific Northwest National Laboratory for the detection of metallic and non-metallic concealed weapons. This technique uses a vertical array of millimeter- wave antennas which is mechanically swept around a person in a cylindrical fashion. The wideband millimeter-wave data is mathematically reconstructed into a series of high- resolution images of the person being screened. Clothing is relatively transparent to millimeter-wave illumination,whereas the human body and concealed items are reflective at millimeter wavelengths. Differences in shape and reflectivity are revealed in the images and allow a human operator to detect and identify concealed weapons. A full 360 degree scan is necessary to fully inspect a person for concealed items. The millimeter-wave images can be formed into a video animation sequence in which the person appears to rotate in front of a fixed illumination source.This is s convenient method for presenting the 3D image data for analysis. This work has been fully sponsored by the FAA. An engineering prototype based on the cylindrical imaging technique is presently under development. The FAA is currently opposed to presenting the image data directly to the operator due to personal privacy concerns. A computer automated system is desired to address this problem by eliminating operator viewing of the imagery.

  2. A Novel Automated Method for Analyzing Cylindrical Computed Tomography Data

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Burke, E. R.; Rauser, R. W.; Martin, R. E.

    2011-01-01

    A novel software method is presented that is applicable for analyzing cylindrical and partially cylindrical objects inspected using computed tomography. This method involves unwrapping and re-slicing data so that the CT data from the cylindrical object can be viewed as a series of 2-D sheets in the vertical direction in addition to volume rendering and normal plane views provided by traditional CT software. The method is based on interior and exterior surface edge detection and under proper conditions, is FULLY AUTOMATED and requires no input from the user except the correct voxel dimension from the CT scan. The software is available from NASA in 32- and 64-bit versions that can be applied to gigabyte-sized data sets, processing data either in random access memory or primarily on the computer hard drive. Please inquire with the presenting author if further interested. This software differentiates itself in total from other possible re-slicing software solutions due to complete automation and advanced processing and analysis capabilities.

  3. The Athena Astrophysical MHD Code in Cylindrical Geometry

    NASA Astrophysics Data System (ADS)

    Skinner, M. A.; Ostriker, E. C.

    2011-10-01

    We have developed a method for implementing cylindrical coordinates in the Athena MHD code (Skinner & Ostriker 2010). The extension has been designed to alter the existing Cartesian-coordinates code (Stone et al. 2008) as minimally and transparently as possible. The numerical equations in cylindrical coordinates are formulated to maintain consistency with constrained transport, a central feature of the Athena algorithm, while making use of previously implemented code modules such as the eigensystems and Riemann solvers. Angular-momentum transport, which is critical in astrophysical disk systems dominated by rotation, is treated carefully. We describe modifications for cylindrical coordinates of the higher-order spatial reconstruction and characteristic evolution steps as well as the finite-volume and constrained transport updates. Finally, we have developed a test suite of standard and novel problems in one-, two-, and three-dimensions designed to validate our algorithms and implementation and to be of use to other code developers. The code is suitable for use in a wide variety of astrophysical applications and is freely available for download on the web.

  4. Finite and infinite wavelength elastocapillary instabilities with cylindrical geometry

    NASA Astrophysics Data System (ADS)

    Biggins, John; Xuan, Chen

    In an elastic cylinder with shear modulus μ, radius R0 and surface tension γ we can define an emergent elastocapillary length l = γ / μ . When this length becomes comparable to R0 the cylinder becomes undergoes a Rayleigh-Plateaux type instability, but surprisingly, with infinite wavelength λ rather than with wavelength λ ~R0 ~ l . Here we take advantage of this infinite wavelength behaviour to construct a simple 1-D model of the elastocapillary instability in a cylindrical gel which permits a high-amplitude fully non-linear treatment. In particular, we show that the instability is sub-critical and entirely dependent on the elastic cylinder being subject to tension. We also discuss elastocapillary instabilities in a range of other cylindrical geometries, such a cylindrical cavities through a bulk elastic solid, or a solid cylinder embedded in a bulk elastic solid, and show that in these cases instability has finite wavelength. Thus infinite wavelength behaviour is a curiosity of elastic cylinders rather than the generic behaviour or elasto-capiliarity. Also Fudan University Shanghai.

  5. The Destructive High Pressure Tests of Cylindrical Shells

    SciTech Connect

    Yasumi Kitajima; Satoru Shibata

    2002-07-01

    We conducted the limit state tests of cylindrical shells to establish criteria for the occurrence of steel wall/liner tearing in the reactor containment vessels (such as Steel Containment Vessels (SCV), Prestressed Concrete Containment Vessels (PCCV) and Reinforced Concrete Containment Vessels (RCCV)) under the limit state pressure. In the tests, precisely manufactured cylindrical shell vessels (about 800 mm in height and 300 mm in diameter) were pressurized to the failure using water. We also conducted the finite element analyses. The conclusions are as follows: 1. We obtained good agreement (within 2-3%) between the tests and the analyses in structural behavior such as internal pressure loading vs. displacement and strain to the failure. However, in the case of the test piece which included weld line on the cylindrical wall, the difference between the tests and the analyses was larger (about 1.5 times) than the rest. 2. The localized strains began to increase when radial strains in general structure reached 5-10%. We are intended to apply these results to the finite element analyses and the integrity evaluation of containment vessels (SCV, PCCV and RCCV). (authors)

  6. Method for fabrication of cylindrical microlenses of selected shape

    DOEpatents

    Snyder, James J.; Baer, Thomas M.

    1992-01-01

    The present invention provides a diffraction limited, high numerical aperture (fast) cylindrical microlens. The method for making the microlens is adaptable to produce a cylindrical lens that has almost any shape on its optical surfaces. The cylindrical lens may have a shape, such as elliptical or hyperbolic, designed to transform some particular given input light distribution into some desired output light distribution. In the method, the desired shape is first formed in a glass preform. Then, the preform is heated to the minimum drawing temperature and a fiber is drawn from it. The cross-sectional shape of the fiber bears a direct relation to the shape of the preform from which it was drawn. During the drawing process, the surfaces become optically smooth due to fire polishing. The present invention has many applications, such as integrated optics, optical detectors and laser diodes. The lens, when connected to a laser diode bar, can provide a high intensity source of laser radiation for pumping a high average power solid state laser. In integrated optics, a lens can be used to couple light into and out of apertures such as waveguides. The lens can also be used to collect light, and focus it on a detector.

  7. Cylindrical effects in weakly nonlinear Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Liu, Wan-Hai; Ma, Wen-Fang; Wang, Xu-Lin

    2015-01-01

    The classical Rayleigh-Taylor instability (RTI) at the interface between two variable density fluids in the cylindrical geometry is explicitly investigated by the formal perturbation method up to the second order. Two styles of RTI, convergent (i.e., gravity pointing inward) and divergent (i.e., gravity pointing outwards) configurations, compared with RTI in Cartesian geometry, are taken into account. Our explicit results show that the interface function in the cylindrical geometry consists of two parts: oscillatory part similar to the result of the Cartesian geometry, and non-oscillatory one contributing nothing to the result of the Cartesian geometry. The velocity resulting only from the non-oscillatory term is followed with interest in this paper. It is found that both the convergent and the divergent configurations have the same zeroth-order velocity, whose magnitude increases with the Atwood number, while decreases with the initial radius of the interface or mode number. The occurrence of non-oscillation terms is an essential character of the RTI in the cylindrical geometry different from Cartesian one. Project supported by the National Basic Research Program of China (Grant No. 10835003), the National Natural Science Foundation of China (Grant No. 11274026), the Scientific Research Foundation of Mianyang Normal University, China (Grant Nos. QD2014A009 and 2014A02), and the National High-Tech ICF Committee.

  8. Chain-based communication in cylindrical underwater wireless sensor networks.

    PubMed

    Javaid, Nadeem; Jafri, Mohsin Raza; Khan, Zahoor Ali; Alrajeh, Nabil; Imran, Muhammad; Vasilakos, Athanasios

    2015-01-01

    Appropriate network design is very significant for Underwater Wireless Sensor Networks (UWSNs). Application-oriented UWSNs are planned to achieve certain objectives. Therefore, there is always a demand for efficient data routing schemes, which can fulfill certain requirements of application-oriented UWSNs. These networks can be of any shape, i.e., rectangular, cylindrical or square. In this paper, we propose chain-based routing schemes for application-oriented cylindrical networks and also formulate mathematical models to find a global optimum path for data transmission. In the first scheme, we devise four interconnected chains of sensor nodes to perform data communication. In the second scheme, we propose routing scheme in which two chains of sensor nodes are interconnected, whereas in third scheme single-chain based routing is done in cylindrical networks. After finding local optimum paths in separate chains, we find global optimum paths through their interconnection. Moreover, we develop a computational model for the analysis of end-to-end delay. We compare the performance of the above three proposed schemes with that of Power Efficient Gathering System in Sensor Information Systems (PEGASIS) and Congestion adjusted PEGASIS (C-PEGASIS). Simulation results show that our proposed 4-chain based scheme performs better than the other selected schemes in terms of network lifetime, end-to-end delay, path loss, transmission loss, and packet sending rate. PMID:25658394

  9. Switching Shape of Cylindrical Brush Molecules at Interfaces

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; da Silva, Marcelo; Prokhorova, Svetlana; Beers, Kathryn; Boerner, Hans; Matyjaszewski, Krzysztof

    2002-03-01

    Significant progress in polymer synthesis has been made towards preparation of three-dimensional macromolecules with well-defined shapes, interiors, and surface structures. The most prominent examples are dendrimers and cylindrical brushes. In contrast to solid particles, hyperbranched macromolecules retain flexibility of chain segments and demonstrate significant density fluctuations. They can be regarded as soft molecular particles, which can change their shape in response to changes in the surrounding environment. The conformational changes are particularly subtle for cylindrical brushes adsorbed to an interface. The surface breaks the molecular symmetry due to partial desorption of the side chains and due to uneven distribution of the side chains with respect to the backbone. The constraints imposed by the branching topology result in a number of distinct conformations and transitions between them. Recently, we have succeeded in monitoring of the conformational changes and motion of individual brush molecules using scanning force microscopy. The most peculiar properties of cylindrical brushes, namely axial contraction, conformational transitions, and persistent motion will be discussed.

  10. Operational characteristics and plasma measurements in cylindrical Hall thrusters

    SciTech Connect

    Shirasaki, Atsushi; Tahara, Hirokazu

    2007-04-01

    The cylindrical Hall thruster (CHT) is an attractive approach to achieve a long lifetime thruster operation especially in low power space applications. Because of the larger volume-to-surface ratio than conventional coaxial Hall thrusters, the cylindrical Hall thrusters are characterized by a reduced heating of the thruster parts and potential lower erosion. Existing CHTs can feature a short coaxial channel in order to sustain a high ionization in the thruster discharge. A 5.6 cm diameter cylindrical Hall thruster was developed and operated with and without a short coaxial region of the thruster channel, in the power range of 70-300 W. It is shown that the CHT without coaxial region can operate stable and achieve higher thrust efficiency, 22%-32% more than that with a coaxial region. Plasma probe measurements inside the thruster channel and ion energy measurements in the plasma plume suggest that the ionization/acceleration region in the CHT is located near the anode region where a radial magnetic field is stronger.

  11. Rayleigh-Taylor instability experiments in a cylindrically convergent geometry

    SciTech Connect

    Goodwin, B.; Weir, S.

    1995-08-25

    Due to the sensitivity of Rayleigh-Taylor instabilities to initial conditions and due to the difficulty of forming well controlled cylindrical or spherical fluid interfaces, Rayleigh-Taylor experiments are often performed with simple, planar interfaces. Rayleigh-Taylor instability phenomena of practical interest, however, (e.g., underwater explosions, supernova core collapses, and inertial confinement fusion capsule implosions) are typically associated with cylindrical or spherical interfaces in which convergent flow effects have an important influence on the dynamics of instability growth. Recently, Meshkov et.al. have developed a novel technique for studying Rayleigh-Taylor instability growth in a cylindrically convergent geometry. Their experiments utilized low-strength gelatin rings which are imploded by a detonating gas mixture of oxygen and acetylene. Since the gelatin itself has sufficient strength to resist significant deformation by gravity, no membranes are needed to define the ring shape. This experimental technique is attractive because it offers a high degree of control over the interfacial geometry and over the material`s strength and rigidity, which can be varied by adjusting the gelatin concentration. Finally, since both the gelatin and the explosive product gases are transparent, optical diagnostics can be used.

  12. Vibration control of cylindrical shells using active constrained layer damping

    NASA Astrophysics Data System (ADS)

    Ray, Manas C.; Chen, Tung-Huei; Baz, Amr M.

    1997-05-01

    The fundamentals of controlling the structural vibration of cylindrical shells treated with active constrained layer damping (ACLD) treatments are presented. The effectiveness of the ACLD treatments in enhancing the damping characteristics of thin cylindrical shells is demonstrated theoretically and experimentally. A finite element model (FEM) is developed to describe the dynamic interaction between the shells and the ACLD treatments. The FEM is used to predict the natural frequencies and the modal loss factors of shells which are partially treated with patches of the ACLD treatments. The predictions of the FEM are validated experimentally using stainless steel cylinders which are 20.32 cm in diameter, 30.4 cm in length and 0.05 cm in thickness. The cylinders are treated with ACLD patches of different configurations in order to target single or multi-modes of lobar vibrations. The ACLD patches used are made of DYAD 606 visco-elastic layer which is sandwiched between two layers of PVDF piezo-electric films. Vibration attenuations of 85% are obtained with maximum control voltage of 40 volts. Such attenuations are attributed to the effectiveness of the ACLD treatment in increasing the modal damping ratios by about a factor of four over those of conventional passive constrained layer damping (PCLD) treatments. The obtained results suggest the potential of the ACLD treatments in controlling the vibration of cylindrical shells which constitute the major building block of many critical structures such as cabins of aircrafts, hulls of submarines and bodies of rockets and missiles.

  13. Electromagnetic field and cylindrical compact objects in modified gravity

    NASA Astrophysics Data System (ADS)

    Yousaf, Z.; Bhatti, M. Zaeem ul Haq

    2016-05-01

    In this paper, we have investigated the role of different fluid parameters particularly electromagnetic field and f(R) corrections on the evolution of cylindrical compact object. We have explored the modified field equations, kinematical quantities and dynamical equations. An expression for the mass function has been found in comparison with the Misner-Sharp formalism in modified gravity, after which different mass-radius diagrams are drawn. The coupled dynamical transport equation have been formulated to discuss the role of thermoinertial effects on the inertial mass density of the cylindrical relativistic interior. Finally, we have presented a framework, according to which all possible solutions of the metric f(R)-Maxwell field equations coupled with static fluid can be written through set of scalar functions. It is found that modified gravity induced by Lagrangians f(R) = αR2, f(R) = αR2 - βR and f(R)=α R^2-β R/1+γ R are likely to host more massive cylindrical compact objects with smaller radii as compared to general relativity.

  14. Determining the axis orientation of cylindrical magnetic flux rope

    NASA Astrophysics Data System (ADS)

    Rong, Zhaojin; Wan, Weixing; Shen, Chao; Zhang, Tielong; Lui, Anthony; Wang, Yuming; Dunlop, malcolm; Zhang, Yongcun; Zong, Qiugang

    2013-04-01

    We develop a new simple method for inferring the orientation of a magnetic flux rope, which is assumed to be a time-independent cylindrically symmetric structure via the direct single-point analysis of magnetic field structure. The model tests demonstrate that, for the cylindrical flux rope regardless of whether it is force-free or not, the method can consistently yield the axis orientation of the flux rope with higher accuracy and stability than the minimum variance analysis of the magnetic field and the Grad-Shafranov reconstruction technique. Moreover, the radial distance to the axis center and the current density can also be estimated consistently. Application to two actual flux transfer events observed by the four satellites of the Cluster mission demonstrates that the method is more appropriate to be used for the inner part of flux rope, which might be closer to the cylindrical structure, showing good agreement with the results obtained from the optimal Grad-Shafranov reconstruction and the least squares technique of Faraday's law, but fails to produce such agreement for the outer satellite that grazes the flux rope. Therefore, the method must be used with caution.

  15. Inflation of stressed cylindrical tubes: an experimental study

    NASA Astrophysics Data System (ADS)

    Guo, Zhiming; Wang, Shibin; Li, Linan; Ji, Hongwei; Wang, Zhiyong; Cai, Songbao

    2014-06-01

    The inflation of an initially stressed cylindrical shell provides a good illustration of the phenomenon of the initiation and propagation of an instability, which shares the same mathematical and mechanical features with a variety of other strain localization phenomena in engineering structures and materials. The high speed CCD camera and digital image processing system were used to measure the 3D shape of the inflated cylindrical tube. The localized bulge of a cylindrical tube with closed ends forms when the internal pressure reaches a critical value Pcr. As more air is filled into the tube, the pressure drops but the radius at the centre of the bulge will increase until it reaches a maximum value rmax. With continued inflation, the pressure stays at a constant value Pp. The purpose of this study is to investigate the critical and propagation pressures in the tubes and the profile outside when the shells under axial tension and internal pressure were inflating. We focus on the influence of the axial tension on the critical pressure. In this paper the problem is explored through experimental efforts. A series of experiments were conducted on commercially available natural rubber latex tubes involving different geometries and initial axial tensions, which were regarded as isotropic, homogeneous, incompressible and hyper-elastic materials.

  16. Chain-Based Communication in Cylindrical Underwater Wireless Sensor Networks

    PubMed Central

    Javaid, Nadeem; Jafri, Mohsin Raza; Khan, Zahoor Ali; Alrajeh, Nabil; Imran, Muhammad; Vasilakos, Athanasios

    2015-01-01

    Appropriate network design is very significant for Underwater Wireless Sensor Networks (UWSNs). Application-oriented UWSNs are planned to achieve certain objectives. Therefore, there is always a demand for efficient data routing schemes, which can fulfill certain requirements of application-oriented UWSNs. These networks can be of any shape, i.e., rectangular, cylindrical or square. In this paper, we propose chain-based routing schemes for application-oriented cylindrical networks and also formulate mathematical models to find a global optimum path for data transmission. In the first scheme, we devise four interconnected chains of sensor nodes to perform data communication. In the second scheme, we propose routing scheme in which two chains of sensor nodes are interconnected, whereas in third scheme single-chain based routing is done in cylindrical networks. After finding local optimum paths in separate chains, we find global optimum paths through their interconnection. Moreover, we develop a computational model for the analysis of end-to-end delay. We compare the performance of the above three proposed schemes with that of Power Efficient Gathering System in Sensor Information Systems (PEGASIS) and Congestion adjusted PEGASIS (C-PEGASIS). Simulation results show that our proposed 4-chain based scheme performs better than the other selected schemes in terms of network lifetime, end-to-end delay, path loss, transmission loss, and packet sending rate. PMID:25658394

  17. THE ATHENA ASTROPHYSICAL MAGNETOHYDRODYNAMICS CODE IN CYLINDRICAL GEOMETRY

    SciTech Connect

    Skinner, M. Aaron; Ostriker, Eve C. E-mail: ostriker@astro.umd.ed

    2010-05-15

    A method for implementing cylindrical coordinates in the Athena magnetohydrodynamics (MHD) code is described. The extension follows the approach of Athena's original developers and has been designed to alter the existing Cartesian-coordinates code as minimally and transparently as possible. The numerical equations in cylindrical coordinates are formulated to maintain consistency with constrained transport (CT), a central feature of the Athena algorithm, while making use of previously implemented code modules such as the Riemann solvers. Angular momentum transport, which is critical in astrophysical disk systems dominated by rotation, is treated carefully. We describe modifications for cylindrical coordinates of the higher-order spatial reconstruction and characteristic evolution steps as well as the finite-volume and CT updates. Finally, we present a test suite of standard and novel problems in one, two, and three dimensions designed to validate our algorithms and implementation and to be of use to other code developers. The code is suitable for use in a wide variety of astrophysical applications and is freely available for download on the Web.

  18. Method for fabrication of cylindrical microlenses of selected shape

    DOEpatents

    Snyder, J.J.; Baer, T.M.

    1992-01-14

    The present invention provides a diffraction limited, high numerical aperture (fast) cylindrical microlens. The method for making the microlens is adaptable to produce a cylindrical lens that has almost any shape on its optical surfaces. The cylindrical lens may have a shape, such as elliptical or hyperbolic, designed to transform some particular given input light distribution into some desired output light distribution. In the method, the desired shape is first formed in a glass preform. Then, the preform is heated to the minimum drawing temperature and a fiber is drawn from it. The cross-sectional shape of the fiber bears a direct relation to the shape of the preform from which it was drawn. During the drawing process, the surfaces become optically smooth due to fire polishing. The present invention has many applications, such as integrated optics, optical detectors and laser diodes. The lens, when connected to a laser diode bar, can provide a high intensity source of laser radiation for pumping a high average power solid state laser. In integrated optics, a lens can be used to couple light into and out of apertures such as waveguides. The lens can also be used to collect light, and focus it on a detector. 11 figs.

  19. Tunnel Point Cloud Filtering Method Based on Elliptic Cylindrical Model

    NASA Astrophysics Data System (ADS)

    Zhua, Ningning; Jiaa, Yonghong; Luo, Lun

    2016-06-01

    The large number of bolts and screws that attached to the subway shield ring plates, along with the great amount of accessories of metal stents and electrical equipments mounted on the tunnel walls, make the laser point cloud data include lots of non-tunnel section points (hereinafter referred to as non-points), therefore affecting the accuracy for modeling and deformation monitoring. This paper proposed a filtering method for the point cloud based on the elliptic cylindrical model. The original laser point cloud data was firstly projected onto a horizontal plane, and a searching algorithm was given to extract the edging points of both sides, which were used further to fit the tunnel central axis. Along the axis the point cloud was segmented regionally, and then fitted as smooth elliptic cylindrical surface by means of iteration. This processing enabled the automatic filtering of those inner wall non-points. Experiments of two groups showed coincident results, that the elliptic cylindrical model based method could effectively filter out the non-points, and meet the accuracy requirements for subway deformation monitoring. The method provides a new mode for the periodic monitoring of tunnel sections all-around deformation in subways routine operation and maintenance.

  20. Macrophage uptake of cylindrical microparticles investigated with correlative microscopy.

    PubMed

    Tscheka, Clemens; Hittinger, Marius; Lehr, Claus-Michael; Schneider-Daum, Nicole; Schneider, Marc

    2015-09-01

    Cylindrical particles offer the opportunity to develop controlled and sustained release systems for the respiratory tract. One reason is that macrophages can phagocyte such particles only from either of the two ends. We investigated the uptake behaviour of murine alveolar macrophages incubated with elongated submicron-structured particles. For that purpose, fluorescent model silica nanoparticles were interconnected with the biocompatible polysaccharide agarose, building up cylindrical particles within the pores of track-etched membranes. In contrast to common approaches we determined the uptake at different time points with scanning electron microscopy, fluorescence microscopy, and the combination of both techniques - correlative microscopy (CLEM). As a consequence, we could securely identify uptake events and observe in detail the engulfment of particles and confirm, that phagocytosis could only be observed from the tips of the cylinders. CLEM allowed a comparison of the uptake measured with different techniques at identical macrophages. Qualitative and quantitative evaluation of this cylindrical particle uptake showed substantial differences between fluorescence microscopy, electron microscopy and the combination of both (CLEM) within 24h. PMID:25779350

  1. Assortative mating without assortative preference

    PubMed Central

    Xie, Yu; Cheng, Siwei; Zhou, Xiang

    2015-01-01

    Assortative mating—marriage of a man and a woman with similar social characteristics—is a commonly observed phenomenon. In the existing literature in both sociology and economics, this phenomenon has mainly been attributed to individuals’ conscious preferences for assortative mating. In this paper, we show that patterns of assortative mating may arise from another structural source even if individuals do not have assortative preferences or possess complementary attributes: dynamic processes of marriages in a closed system. For a given cohort of youth in a finite population, as the percentage of married persons increases, unmarried persons who newly enter marriage are systematically different from those who married earlier, giving rise to the phenomenon of assortative mating. We use microsimulation methods to illustrate this dynamic process, using first the conventional deterministic Gale–Shapley model, then a probabilistic Gale–Shapley model, and then two versions of the encounter mating model. PMID:25918366

  2. Review: Thermal preference in Drosophila

    PubMed Central

    Dillon, Michael E.; Wang, George; Garrity, Paul A.; Huey, Raymond B.

    2009-01-01

    Environmental temperature strongly affects physiology of ectotherms. Small ectotherms, like Drosophila, cannot endogenously regulate body temperature so must rely on behavior to maintain body temperature within a physiologically permissive range. Here we review what is known about Drosophila thermal preference. Work on thermal behavior in this group is particularly exciting because it provides the opportunity to connect genes to neuromolecular mechanisms to behavior to fitness in the wild. PMID:20161211

  3. Where Would Refinancing Preferences Go?

    NASA Astrophysics Data System (ADS)

    Chai, Yajun; Liu, Bo

    We study the relation between the non-tradable shares reform and the refinancing preferences. From the viewpoints of change in market and policy environments led by the reform, we find that right issues dominate before the reform, however, public offerings (including private placement) dominate after reform, which could be attributed to more money encirclement induced by the shift of the public offering mechanism from in discount to in premium after reform and no requirements for large shareholders' participation commitments in public offerings.

  4. Preferred and actual relative height among homosexual male partners vary with preferred dominance and sex role.

    PubMed

    Valentova, Jaroslava Varella; Stulp, Gert; Třebický, Vít; Havlíček, Jan

    2014-01-01

    Previous research has shown repeatedly that human stature influences mate preferences and mate choice in heterosexuals. In general, it has been shown that tall men and average height women are most preferred by the opposite sex, and that both sexes prefer to be in a relationship where the man is taller than the woman. However, little is known about such partner preferences in homosexual individuals. Based on an online survey of a large sample of non-heterosexual men (N = 541), we found that the majority of men prefer a partner slightly taller than themselves. However, these preferences were dependent on the participant's own height, such that taller men preferred shorter partners, whereas shorter men preferred taller partners. We also examined whether height preferences predicted the preference for dominance and the adoption of particular sexual roles within a couple. Although a large proportion of men preferred to be in an egalitarian relationship with respect to preferred dominance (although not with respect to preferred sexual role), men that preferred a more dominant and more "active" sexual role preferred shorter partners, whereas those that preferred a more submissive and more "passive" sexual role preferred taller partners. Our results indicate that preferences for relative height in homosexual men are modulated by own height, preferred dominance and sex role, and do not simply resemble those of heterosexual women or men. PMID:24466136

  5. Preferred and Actual Relative Height among Homosexual Male Partners Vary with Preferred Dominance and Sex Role

    PubMed Central

    Valentova, Jaroslava Varella; Stulp, Gert; Třebický, Vít; Havlíček, Jan

    2014-01-01

    Previous research has shown repeatedly that human stature influences mate preferences and mate choice in heterosexuals. In general, it has been shown that tall men and average height women are most preferred by the opposite sex, and that both sexes prefer to be in a relationship where the man is taller than the woman. However, little is known about such partner preferences in homosexual individuals. Based on an online survey of a large sample of non-heterosexual men (N = 541), we found that the majority of men prefer a partner slightly taller than themselves. However, these preferences were dependent on the participant’s own height, such that taller men preferred shorter partners, whereas shorter men preferred taller partners. We also examined whether height preferences predicted the preference for dominance and the adoption of particular sexual roles within a couple. Although a large proportion of men preferred to be in an egalitarian relationship with respect to preferred dominance (although not with respect to preferred sexual role), men that preferred a more dominant and more “active” sexual role preferred shorter partners, whereas those that preferred a more submissive and more “passive” sexual role preferred taller partners. Our results indicate that preferences for relative height in homosexual men are modulated by own height, preferred dominance and sex role, and do not simply resemble those of heterosexual women or men. PMID:24466136

  6. A Solid Core Heatpipe Reactor with Cylindrical Thermoelectric Converter Modules

    SciTech Connect

    Sayre, Edwin D.; Vaidyanathan, Sam

    2006-01-20

    A nuclear space power system that consists of a solid metal nuclear reactor core with heat pipes carrying energy to a cylindrical thermoelectric converter surrounding each of the heat pipes with a heat pipe radiator surrounding the thermoelectric converter is the most simple and reliable space power system. This means no single point of failure since each heat pipe and cylindrical converter is a separate power system and if one fails it will not affect the others. The heat pipe array in the solid core is designed so that if an isolated heat pipe or even two adjacent heat pipes fail, the remaining heat pipes will still transport the core heat without undue overheating of the uranium nitride fuel. The primary emphasis in this paper is on simplicity, reliability and fabricability of such a space nuclear power source. The core and heat pipes are made of Niobium 1% Zirconium alloy (Nb1Zr), with rhenium lined fuel tubes, bonded together by hot isostatic pressure (HIPing) and with sodium as the heat pipe working fluid, can be operated up to 1250K. The cylindrical thermoelectric converter is made by depositing the constituents of the converter around a Nb1%Zr tube and encasing it in a Nb 1% Zr alloy tube and HIPing the structure to get final bonding and to produce residual compressive stresses in all brittle materials in the converter. A radiator heat pipe filled with potassium that operates at 850K is bonded to the outside of the cylindrical converter for cooling. The solid core heat pipe and cylindrical converter are mated by welding during the final assembly. A solid core reactor with 150 heat pipes with a 0.650-inch (1.65 cm) ID and a 30-inch (76.2 cm) length with an output of 8 Watts per square inch as demonstrated by the SP100 PD2 cell tests will produce about 80 KW of electrical power. An advanced solid core reactor made with molybdenum 47% rhenium alloy, with lithium heat pipes and the PD2 theoretical output of 11 watts per square inch or advanced higher

  7. A Solid Core Heatpipe Reactor with Cylindrical Thermoelectric Converter Modules

    NASA Astrophysics Data System (ADS)

    Sayre, Edwin D.; Vaidyanathan, Sam

    2006-01-01

    A nuclear space power system that consists of a solid metal nuclear reactor core with heat pipes carrying energy to a cylindrical thermoelectric converter surrounding each of the heat pipes with a heat pipe radiator surrounding the thermoelectric converter is the most simple and reliable space power system. This means no single point of failure since each heat pipe and cylindrical converter is a separate power system and if one fails it will not affect the others. The heat pipe array in the solid core is designed so that if an isolated heat pipe or even two adjacent heat pipes fail, the remaining heat pipes will still transport the core heat without undue overheating of the uranium nitride fuel. The primary emphasis in this paper is on simplicity, reliability and fabricability of such a space nuclear power source. The core and heat pipes are made of Niobium 1% Zirconium alloy (Nb1Zr), with rhenium lined fuel tubes, bonded together by hot isostatic pressure, (HIPing) and with sodium as the heat pipe working fluid, can be operated up to 1250K. The cylindrical thermoelectric converter is made by depositing the constituents of the converter around a Nb1%Zr tube and encasing it in a Nb 1% Zr alloy tube and HIPing the structure to get final bonding and to produce residual compressive stresses in all brittle materials in the converter. A radiator heat pipe filled with potassium that operates at 850K is bonded to the outside of the cylindrical converter for cooling. The solid core heat pipe and cylindrical converter are mated by welding during the final assembly. A solid core reactor with 150 heat pipes with a 0.650-inch (1.65 cm) ID and a 30-inch (76.2 cm) length with an output of 8 Watts per square inch as demonstrated by the SP100 PD2 cell tests will produce about 80 KW of electrical power. An advanced solid core reactor made with molybdenum 47% rhenium alloy, with lithium heat pipes and the PD2 theoretical output of 11 watts per square inch or advanced higher

  8. Human Preferences for Conformation Attributes and Head-And-Neck Positions in Horses.

    PubMed

    Caspar, Georgina L; Dhand, Navneet K; McGreevy, Paul D

    2015-01-01

    Human preferences for certain morphological attributes among domestic animals may be entirely individual or, more generally, may reflect evolutionary pressures that favor certain conformation. Artificial selection for attributes, such as short heads and crested necks of horses, may have functional and welfare implications because there is evidence from other species that skull shape co-varies with behaviour. Crested necks can be accentuated by flexion of the neck, a quality that is often manipulated in photographs vendors use when selling horses. Equine head-and-neck positions acquired through rein tension can compromise welfare. Our investigation was designed to identify conformations and postures that people are attracted to when choosing their 'ideal' horse. Participants of an internet survey were asked to rate their preference for horse silhouettes that illustrated three gradations of five variables: facial shape, crest height, ear length, ear position and head-and-neck carriage. There were 1,234 usable responses. The results show that overall preferences are for the intermediate, rather than extreme, morphological choices (p=<0.001). They also indicate that males are 2.5 times less likely to prefer thicker necks rather than the intermediate shape, and 4 times more likely to prefer the thinner neck shape. When compared to the novice participants, experienced participants were 1.9 times more likely to prefer a thicker neck shape than the intermediate neck shape and 2.8 times less likely to prefer a thinner neck shape than the intermediate neck shape. There was overall preference of 93% (n=939) for the category of head carriage 'In front of the vertical'. However, novice participants were 1.8 times more likely to choose 'behind the vertical' than 'in front of the vertical'. Our results suggest that people prefer a natural head carriage, concave facial profile (dished face), larger ears and thicker necks. From these survey data, it seems that some innate

  9. Apparatus For Converging Cylindrical Shock Wave In Water Generated By Pulsed Multi-Streamer Discharge At One Cylindrical Electrode

    SciTech Connect

    Vaclav, Prukner; Karel, Kolacek; Jiri, Schmidt; Jaroslav, Straus; Oleksandr, Frolov; Martinkova, Michaela

    2006-01-15

    The paper reports on set-up of the apparatus for converging cylindrical shock wave in water and its first test experiments. The first part of this paper describes set-up of the apparatus. In the second part there are reported the first experiment results. The experiment is aimed at obtaining evidence of shock wave and its localization. As a prove that the shock wave is generated the disintegration of cellular tissue in its focus was used.

  10. Electromagnetic response of buried cylindrical structures for line current excitation

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Ponti, Cristina

    2013-04-01

    The Cylindrical-Wave Approach (CWA) rigorously solves, in the spectral domain, the electromagnetic forward scattering by a finite set of buried two-dimensional perfectly-conducting or dielectric objects [1]-[2]. In this technique, the field scattered by underground objects is represented in terms of a superposition of cylindrical waves. Use is made of the plane-wave spectrum [1] to take into account the interaction of such waves with the planar interface between air and soil, and between different layers eventually present in the ground [3]. Obstacles of general shape can be simulated through the CWA with good results, by using a suitable set of small circular-section cylinders [4]. Recently, we improved the CWA by facing the fundamental problem of losses in the ground [5]: this is of significant importance in remote-sensing applications, since real soils often have complex permittivity and conductivity, and sometimes also a complex permeability. While in previous works concerning the CWA a monochromatic or pulsed plane-wave incident field was considered, in the present work a different source of scattering is present: a cylindrical wave radiated by a line source. Such a source is more suitable to model the practical illumination field used in GPR surveys. The electric field radiated by the line current is expressed by means of a first-kind Hankel function of 0-th order. The theoretical solution to the scattering problem is developed for both dielectric and perfectly-conducting cylinders buried in a dielectric half-space. The approach is implemented in a Fortran code; an accurate numerical evaluation of the involved spectral integrals is performed, the highly-oscillating behavior of the homogeneous waves is correctly followed and evanescent contributions are taken into account. The electromagnetic field scattered in both air and ground can be obtained, in near- and far-field regions, for arbitrary radii and permittivity of the buried cylinders, as well as for

  11. Chaotic Energy Exchange Through Auto-Parametric Resonance in Cylindrical Shells

    NASA Astrophysics Data System (ADS)

    POPOV, A. A.; THOMPSON, J. M. T.; MCROBIE, F. A.

    2001-11-01

    Internal auto-parametric instabilities in the free non-linear vibrations of a cylindrical shell are studied numerically, focusing on two modes (a concertina mode and a chequerboard mode) whose non-linear interaction breaks the in-out symmetry of the linear vibration theory. The two-mode interaction leads to preferred vibration patterns with larger deflection inwards than outwards, and at internal resonance, significant energy transfer occurs between the modes. This has regular and chaotic features. Here, direct numerical integration is employed to examine chaotic motions. Using a set of 2-D Poincaré sections, each valid for a fixed level of the Hamiltonian, H, the instability under increasing H appears, as a supercritical period-doubling pitchfork bifurcation. Chaotic motions near a homoclinic separatrix appear immediately after the bifurcation, giving an irregular exchange of energy. This chaos occurs at arbitrarily low amplitude as perfect tuning is approached. The instability manifests itself as repeating excursions around the separatrix, and a number of practical predictions can be made. These include the magnitude of the excursion, the time taken to reach this magnitude and the degree of chaos and unpredictability in the outcome. The effect of small damping is to pull the motion away from what was the chaotic separatrix, giving a response that resembles, for a while, the lower-energy quasi-periodic orbits of the underlying Hamiltonian system.

  12. A cylindrical model for rotational MHD instabilities in aluminum reduction cells

    NASA Astrophysics Data System (ADS)

    Munger, David; Vincent, Alain

    2008-08-01

    Large-scale horizontal vortices associated with deformations of the aluminum-electrolyte interface have been observed in operating aluminum reduction cells as well as in physical and numerical models. To expose their importance, we analyze a particular class of magnetohydrodynamic (MHD) interfacial instabilities which are induced by rotation. As we focus on a single vortex, a cylindrical geometry is preferred. Two analytical models are proposed. In a first model based on the MHD shallow-water approximation, we consider a vortex that has a solid rotation profile to obtain a wave equation and a dispersion relation. A more realistic second model includes a viscous rotation profile and the treatment of the base-state interface deformation. Energetics of the flow gives further insight on how an initial perturbation evolves as an oscillatory or a non-oscillatory instability, depending on the direction of rotation. We find that the mechanism at the very origin of these instabilities is neither due to a shear between the two layers—and are therefore not Kelvin Helmholtz instabilities—nor simply due to magnetic force alone, but rather to the indirect action of the centripetal pressure due to the rotation induced by magnetic force.

  13. Minimum weight design of ring and stringer stiffeners for axially compressed cylindrical shells with and without internal pressure

    NASA Technical Reports Server (NTRS)

    Block, D. L.

    1972-01-01

    Results of analytical study to determine desirable ring and stringer stiffener parameters and proportions for axially compressed stiffened isotropic cylinders with and without internal pressure are presented. This investigation examines the panel and general instability buckling modes of a stiffened cylindrical shell and from this determines desirable stiffener parameters and proportions. Classical buckling equations are used which retain the important effects of the stiffeners. The results determined by using the simpler classical buckling equations are then spot checked and verified using buckling equations which considered discrete ring stiffeners and nonlinear prebuckling deformations. For both rings and stringers, T-shaped stiffeners are preferable and the effects to stiffener shape are much more pronounced at low or zero values of the internal pressure parameter. Simple analytical expressions are developed and presented which express the stiffener area parameter, the ratio of stiffener area and elastics to shell wall area and elastic modulus, in terms of the cylinder geometry and internal pressure parameter.

  14. Dimensions of Preschool Children's Food Preferences.

    ERIC Educational Resources Information Center

    Birch, Leann Lipps

    1979-01-01

    Describes four assessments which preschool children were given to indicate preference for a set of fruits. The research demonstrates the feasibility of obtaining preference data directly from young children. (Author/SA)

  15. Rat preference for food-related odors.

    PubMed

    Tabuchi, E; Ono, T; Uwano, T; Takashima, Y; Kawasaki, M

    1991-01-01

    Preferences for food-related odors and the effects of fasting on those preferences were investigated during rat bar pressing for brief odor presentation. A rat was housed in an equilateral octagonal cage and had free access to food and water, except during fasting. Among 8 food-related odor substances (black pepper, cheese, coffee, milk, nut, peppermint, plum and orange), black pepper, milk and coffee were most preferred, and cheese was least preferred, but even the bar pressing rate for cheese was above the operant level. This data indicates that all 8 odors were preferred by rats, although there were different degrees of preference in individual animals. Fasting substantially increased the rate of bar pressing for odors and changed the odors preferences. This result was probably due to increased search for food and water. Since bar pressing was reinforced by nothing other than odor presentation, the results reveal inherent odor preferences of rats. PMID:1959035

  16. Teacher Preferences for Various Positive Reinforcements.

    ERIC Educational Resources Information Center

    Derevensky, Jeffrey L.; Rose, Malcolm I.

    1978-01-01

    Investigated the relationship between applied behavioral training and reinforcement preferences of classroom teachers. Data obtained from the Positive Reinforcement Observation Schedule, a paired comparison task, indicated minimal differential reinforcement preferences for classroom teachers with no training, limited training, or extensive…

  17. The shy prefer familiar congeners.

    PubMed

    Benhaïm, David; Ferrari, Sébastien; Chatain, Béatrice; Bégout, Marie-Laure

    2016-05-01

    The shy-bold continuum is both a fundamental aspect of human behavior and a relatively stable behavioral trait for many other species. Here we assessed whether shy individuals prefer familiar congeners, taking the European sea bass, a recently domesticated fish showing similar behavioral responses to wild fish, as a model to better understand the inter-individual variability in social behavior previously observed in this species. In the wild, the link between familiarity i.e., the preference of fish for familiar congeners and boldness could be part of the mechanism underlying shoaling formation in fish. Thirty fish were individually tested in a device designed to assess the preference for a familiar vs. an unfamiliar congener on the basis of visual cues only. An open field test (OFT) with shelter was performed on the same fish 32 days later to assess the boldness of each individual. Variables of interest included the proportion of time spent in the shelter, border and center zone of the arena and variables of activity. Variables measured in OFT were collapsed into first principal component scores using Principal Components Analysis (PCA) which allowed characterizing a shy-bold continuum. Time spent near the familiar congener was negatively correlated with boldness i.e., shy individuals spent most of the time near the familiar congener. We discuss the relevance of these findings to the understanding of the behavior of European sea bass and suggest that the link between familiarity and shyness is a general aspect of both animal and human behavior. PMID:26995491

  18. Intergenerational transfer of time and risk preferences

    PubMed Central

    Brown, Heather; van der Pol, Marjon

    2015-01-01

    There is a growing interest in individual time and risk preferences. Little is known about how these preferences are formed. It is hypothesised that parents may transmit their preferences to their offspring. This paper examines the correlation in offspring and parental time and risk preferences using data from an annual household survey in Australia (the HILDA survey). Both time and risk preferences are examined and we explored whether the correlation in time and risk preferences varies across the distribution of preferences and across the across the four parent–child dyads (mother/daughter, mother/son, father/daughter, father/son). The results show that there is a significant relationship between parents and their young adult offspring risk and time preference measures. The correlation varies across the distribution of time preferences. The correlation was largest for longer planning horizons. Risk averse parents are more likely to have risk averse children. Except for the father/daughter dyad risk seeking parents are more likely to have risk seeking offspring. Some gender differences were found. The association in parental and offspring time preference was larger for mothers than fathers. Daughters are more likely to be influenced by their mother’s risk preferences, however, sons are equally influenced by both parents. The results of this study suggest that the transmission in preferences is more nuanced than previously thought and parental gender may be important. PMID:26412913

  19. 4 CFR 2.6 - Veterans' preference.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 4 Accounts 1 2010-01-01 2010-01-01 false Veterans' preference. 2.6 Section 2.6 Accounts GOVERNMENT ACCOUNTABILITY OFFICE PERSONNEL SYSTEM PURPOSE AND GENERAL PROVISION § 2.6 Veterans' preference. (a) GAO will... preference decisions will be heard by the GAO Personnel Appeals Board....

  20. Business Education Students' Preferred Learning Styles.

    ERIC Educational Resources Information Center

    Stitt-Gohdes, Wanda L.

    2001-01-01

    Results of the Canfield Learning Styles Inventory, completed by 212 secondary business students, showed that most preferred direct experience--hands-on learning. Least preferred was reading, including textbook assignments. Nearly half (98) clustered around applied and independent learning preferences. (SK)

  1. Preschoolers Use Speakers' Preferences to Learn Words

    ERIC Educational Resources Information Center

    Saylor, Megan M.; Sabbagh, Mark A.; Fortuna, Alexandra; Troseth, Georgene

    2009-01-01

    In two studies, we investigated preschoolers' ability to use others' preferences to learn names for things. Two studies demonstrated that preschool children make smart use of others' preferences. In the first study, preschool children only used information about others' preferences when they were clearly linked to referential intentions. The…

  2. Generalization of a Modified Food Preference.

    ERIC Educational Resources Information Center

    Birch, Leann Lipps

    1981-01-01

    Assesses preschool children's preferences for eight snack foods and tests procedures to modify preferences for certain foods by having children sort foods according to self-determined categories. Enhanced preferences for target foods generalized to other foods in the same category only for children using semantic sorting categories. (Author/DB)

  3. Vision and the End of Racial Preferences

    ERIC Educational Resources Information Center

    Clegg, Roger

    2008-01-01

    Are we facing the end of racial preferences in America? Mr. Clegg thinks we probably are, and examines the role demographics, law, attraction, and vision may play in their demise. What makes preferences still attractive to so many people? Do most Americans share a vision that includes the continued use of racial preferences? Mr. Clegg offers a…

  4. Minimal Mimicry: Mere Effector Matching Induces Preference

    ERIC Educational Resources Information Center

    Sparenberg, Peggy; Topolinski, Sascha; Springer, Anne; Prinz, Wolfgang

    2012-01-01

    Both mimicking and being mimicked induces preference for a target. The present experiments investigate the minimal sufficient conditions for this mimicry-preference link to occur. We argue that mere effector matching between one's own and the other person's movement is sufficient to induce preference, independent of which movement is actually…

  5. Tempo Preferences of Different Age Music Listeners.

    ERIC Educational Resources Information Center

    LeBlanc, Albert; And Others

    1988-01-01

    Measures the effect of four levels of tempo on the self-reported preferences of six different age-groups for traditional jazz music listening examples. Stated that listener age exerted a strong influence on overall preference scores. Reported an analysis of variance showing that there is a significant preference for increasingly faster tempo at…

  6. Subject Preference Regarding Three Psychotherapy Orientations.

    ERIC Educational Resources Information Center

    Hollis, Thomas G.

    Research has shown that therapy preference affects both the quality of the initial therapy session and treatment outcome. To determine personality characteristics which would affect subjects' preference of therapeutic orientation and to obtain qualitative information about subjects' therapy preferences, 203 community college students indicated…

  7. Preferred Attachment in Affiliation Networks

    NASA Astrophysics Data System (ADS)

    Bloznelis, Mindaugas; Götze, Friedrich

    2014-08-01

    Vertices of an affiliation network are linked to attributes and two vertices are declared adjacent whenever they share a common attribute. For example, two customers of an internet shop (or video-sharing website) are called adjacent if they have purchased (or downloaded) the same or similar items. Assuming that each newly arrived customer is linked preferentially to already popular items we obtain a preferred attachment affiliation network that evolves in time. We show that the fraction of customers having neighbours scales as for large . Here is the ratio between the two intensities: intensity of the flow of customers and that of the newly arriving items.

  8. Kinematics of preferred and non-preferred handballing in Australian football.

    PubMed

    Parrington, Lucy; Ball, Kevin; MacMahon, Clare

    2015-01-01

    In Australian football (AF), handballing proficiently with both the preferred and non-preferred arm is important at elite levels; yet, little information is available for handballing on the non-preferred arm. This study compared preferred and non-preferred arm handballing techniques. Optotrak Certus (100 Hz) collected three-dimensional data for 19 elite AF players performing handballs with the preferred and non-preferred arms. Position data, range of motion (ROM), and linear and angular velocities were collected and compared between preferred and non-preferred arms using dependent t-tests. The preferred arm exhibited significantly greater forearm and humerus ROM and angular velocity and significantly greater shoulder angular velocity at ball contact compared to the non-preferred arm. In addition, the preferred arm produced a significantly greater range of lateral bend and maximum lower-trunk speed, maximum strike-side hip speed and hand speed at ball contact than the non-preferred arm. The non-preferred arm exhibited a significantly greater shoulder angle and lower- and upper-trunk orientation angle, but significantly lower support-elbow angle, trunk ROM, and trunk rotation velocity compared to the preferred arm. Reduced ROM and angular velocities found in non-preferred arm handballs indicates a reduction in the degrees of freedom and a less developed skill. Findings have implication for development of handballing on the non-preferred arm. PMID:24863906

  9. Three-step cylindrical seal for high-performance turbomachines

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.

    1987-01-01

    A three-step cylindrical seal configuration representing the seal for a high performance turbopump (e.g., the space shuttle main engine fuel pump) was tested under static (nonrotating) conditions. The test data included critical mass flux and pressure profiles over a wide range of inlet temperatures and pressures for fluid nitrogen and fluid hydrogen with the seal in concentric and fully eccentric positions. The critical mass flux (leakage rate) was 70% that of an equivalent straight cylindrical seal with a correspondingly higher pressure drop based on the same flow areas of 0.3569 sq cm but 85% that of the straight seal based on the third-step flow area of 0.3044 sq cm. The mass flow rates for the three step cylindrical seal in the fully eccentric and concentric positions were essentially the same, and the trends in flow coefficient followed those of a simple axisymmetric inlet configuration. However, for inlet stagnation temperatures less than the thermodynamic critical temperature the pressure profiles exhibited a flat region throughout the third step of the seal, with the pressure magnitude dependent on the inlet stagnation temperature. Such profiles represent an extreme positive direct stiffness. These conditions engendered a crossover in the pressure profile upstream of the postulated choke that resulted in a local negative stiffness. Flat and crossover profiles resulting from choking within the seal are practically unknown to the seal designer. However, they are of critical importance to turbomachine stability and must be integrated into any dynamic analysis of a seal of this configuration. In addition, choking is highly dependent on geometry, inlet-to-backpressure ratio, and inlet temperature and can occur within the seal even though the backpressure is above the critical pressure.

  10. Three-step cylindrical seal for high-performance turbomachines

    NASA Astrophysics Data System (ADS)

    Hendricks, Robert C.

    1987-06-01

    A three-step cylindrical seal configuration representing the seal for a high performance turbopump (e.g., the space shuttle main engine fuel pump) was tested under static (nonrotating) conditions. The test data included critical mass flux and pressure profiles over a wide range of inlet temperatures and pressures for fluid nitrogen and fluid hydrogen with the seal in concentric and fully eccentric positions. The critical mass flux (leakage rate) was 70% that of an equivalent straight cylindrical seal with a correspondingly higher pressure drop based on the same flow areas of 0.3569 sq cm but 85% that of the straight seal based on the third-step flow area of 0.3044 sq cm. The mass flow rates for the three step cylindrical seal in the fully eccentric and concentric positions were essentially the same, and the trends in flow coefficient followed those of a simple axisymmetric inlet configuration. However, for inlet stagnation temperatures less than the thermodynamic critical temperature the pressure profiles exhibited a flat region throughout the third step of the seal, with the pressure magnitude dependent on the inlet stagnation temperature. Such profiles represent an extreme positive direct stiffness. These conditions engendered a crossover in the pressure profile upstream of the postulated choke that resulted in a local negative stiffness. Flat and crossover profiles resulting from choking within the seal are practically unknown to the seal designer. However, they are of critical importance to turbomachine stability and must be integrated into any dynamic analysis of a seal of this configuration. In addition, choking is highly dependent on geometry, inlet-to-backpressure ratio, and inlet temperature and can occur within the seal even though the backpressure is above the critical pressure.

  11. Preference of the herbivorous marine teleost Siganus canaliculatus for different macroalgae

    NASA Astrophysics Data System (ADS)

    You, Cuihong; Zeng, Fangui; Wang, Shuqi; Li, Yuanyou

    2014-06-01

    The decomposition of a large amount of unexploited macroalgal resource along the coast of China often results in heavy environmental pollution. In order to pave a way of using macroalgae as the dietary ingredient of rabbitfish Siganus canaliculatus, one of a few farmed herbivorous marine teleosts in China, its preference (feeding selectivity) for different macroalgae was determined in this study. Seven seaweed species abundantly inhabiting the coast of east Guangdong Province were exposed simultaneously to rabbitfish juveniles in laboratory (multiple-choice feeding) with their content and absolute intake assayed. It was found that the most preferred algae were Ulva prolifera, Gracilaria lemaneiformis and Chaetomorpha linum, less preferred algae were U. pertusa and Porphyra haitanensis, and least preferred ones were Sargassum fusiforme and Corallina sessilis. Such an order did not change when one to four relatively preferred seaweeds were removed. The preferred seaweeds were richer in protein and soluble sugar thus higher in energy than the least preferred. In addition, this fish was found to favor filamentous and flat algae rather than calcified ones. Accordingly, the richness of nutrients and morphological characteristics determined the preference of S. canaliculatus for tested macroalgae.

  12. Load Tests on a Stiffened Circular Cylindrical Shell

    NASA Technical Reports Server (NTRS)

    Schapitz, E; Krumling, G

    1938-01-01

    The present report describes tests in which the stress distribution may be determined in a stiffened circular cylindrical shell loaded longitudinally at four symmetrically situated points. As being of particular importance are the cases investigated of groups of bending and arching or convexing forces, respectively. From the stress measurements on the longitudinal stiffeners, the shear stresses and the bulkhead ring stresses in the skin could be evaluated. These measurements showed that the "simple shear field" used in theoretical computations in which all normal stresses in the skin are neglected, must be extended by the addition of the transverse or circumferential stresses if the bulkhead rings are not riveted to the skin.

  13. An experimental investigation of flame behavior during cylindrical vessel explosions

    NASA Astrophysics Data System (ADS)

    Starke, R.; Roth, P.

    1986-12-01

    The propagation of premixed flames centrally ignited at one of the end flanges of a closed cylindrical vessel and the flame-induced flow have been investigated. Photographic records show that under specific geometrical conditions the flame exhibits a cone form with a backward directed top, called tulip-shaped. This appears after the flame has lost a main part of its area by side wall quenching. The instantaneous flow velocity during the short explosion process was measured, together with pressure records, with an LDV. An analogy to the experiments of Markstein (1964), is shown, and the explanations of several authors for the 'tulip' formation are given.

  14. An experimental investigation of flame behavior during cylindrical vessel explosions

    SciTech Connect

    Starke, R.; Roth, P.

    1986-12-01

    The propagation of premixed flames centrally ignited at one of the end flanges of a closed cylindrical vessel and the flame-induced fluid flow have been investigated in the present study. Photographic records show that under specific geometrical conditions the flame exhibits a cone form with a backward directed top, called ''tulip'' -shaped. This appears after the flame has lost a main part of its area by side wall quenching. With a laser-Doppler anemometer the instantaneous flow velocity during the short explosion process was measured together with pressure records.

  15. A new cylindrical drift chamber for the MEG II experiment

    NASA Astrophysics Data System (ADS)

    Baldini, A. M.; Baracchini, E.; Berretta, L.; Bianucci, S.; Cavoto, G.; Chiarello, G.; Chiri, C.; Cei, F.; Corvaglia, A.; Dussoni, S.; Fahrni, D.; Galli, L.; Grancagnolo, F.; Grassi, M.; Hofer, A.; Hildebrandt, M.; Ignatov, F.; Miccoli, A.; Nicolò, D.; Orsini, A.; Panareo, M.; Pepino, A.; Pinto, C.; Piredda, G.; Signorelli, G.; Raffaelli, F.; Recchia, L.; Renga, F.; Ripiccini, E.; Tassielli, G.; Tazzioli, A.; Tenchini, F.; Venturini, M.; Voena, C.; Zullo, A.

    2016-07-01

    A new cylindrical drift chamber is currently under construction for the MEG II experiment. The chamber is meant to track low momentum positrons from μ+ decays to search for μ+ →e+ γ events. The detector is segmented in very small drift cells, placed in stereo configuration and operated in a helium-isobutane gas mixture. The use of thin aluminium wires and light gas mixture set the total radiation length of the chamber to only 1.6 ×10-3X0 per track turn allowing for a momentum resolution of ~120 keV/c.

  16. Results from the E835 cylindrical scintillating-fiber tracker

    SciTech Connect

    Ambrogiani, M.; Baldini, W.; Bettoni, D.; Calabrese, R.; Luppi, E.; Mussa, R.; Stancari, G. |

    1998-11-01

    A cylindrical 860-channel scintillating-fiber tracker for the measurement of the polar coordinate {theta} has been built for experiment 835 at Fermi National Accelerator Laboratory; it was used during the data-taking period, from October 1996 through September 1997. The high granularity, flexibility and fast response of the scintillating fibers are combined with the high quantum efficiency of the Visible-Light Photon Counters. From this combination, a new kind of detector arises, capable of high-resolution tracking, fast first-level kinematical triggering and single/double-track discrimination. Results of the tracker performance are presented. {copyright} {ital 1998 American Institute of Physics.}

  17. Two-dimensional magnetohydrodynamic turbulence - Cylindrical, non-dissipative model

    NASA Technical Reports Server (NTRS)

    Montgomery, D.; Vahala, G.

    1979-01-01

    Incompressible magnetohydrodynamic turbulence is treated in the presence of cylindrical boundaries which are perfectly conducting and rigidly smooth. The model treated is non-dissipative and two-dimensional, the variation of all quantities in the axial direction being ignored. Equilibrium Gibbs ensemble predictions are explored assuming the constraint of constant axial current (appropriate to tokamak operation). No small-amplitude approximations are made. The expectation value of the turbulent kinetic energy is found to approach zero for the state of maximum mean-square vector potential to energy ratio. These are the only states for which large velocity fluctuations are not expected.

  18. Preliminary analysis techniques for ring and stringer stiffened cylindrical shells

    NASA Technical Reports Server (NTRS)

    Graham, J.

    1993-01-01

    This report outlines methods of analysis for the buckling of thin-walled circumferentially and longitudinally stiffened cylindrical shells. Methods of analysis for the various failure modes are presented in one cohesive package. Where applicable, more than one method of analysis for a failure mode is presented along with standard practices. The results of this report are primarily intended for use in launch vehicle design in the elastic range. A Microsoft Excel worksheet with accompanying macros has been developed to automate the analysis procedures.

  19. Controlling the Plasma Flow in the Miniaturized Cylindrical Hall Thruster

    SciTech Connect

    A. Smirnov, Y. Raitses and N.J. Fisch

    2008-03-04

    A substantial narrowmg of the plume of the cylindrical RaIl thruster (CRT) was observed upon the enhancement of the electron emission from the hollow cathode discharge, which implies the possibility for the thruster efficiency increase due to the ion beam focusing. It is demonstrated that the miniaturized CRT can be operated in the non-self-sustained regime, with the discharge current limited by the cathode electron emission. The thruster operation in this mode greatly expands the range of the plasma and discharge parameters normally accessible for the CRT.

  20. A higher order theory of laminated composite cylindrical shells

    NASA Technical Reports Server (NTRS)

    Krishna Murthy, A. V.; Reddy, T. S. R.

    1986-01-01

    A new higher order theory has been proposed for the analysis of composite cylindrical shells. The formulation allows for arbitrary variation of inplane displacements. Governing equations are presented in the form of a hierarchy of sets of partial differential equations. Each set describes the shell behavior to a certain degree of approximation. The natural frequencies of simply-supported isotropic and laminated shells and stresses in a ring loaded composite shell have been determined to various orders of approximation and compared with three dimensional solutions. These numerical studies indicate the improvements achievable in estimating the natural frequencies and the interlaminar shear stresses in laminated composite cylinders.

  1. Sound transmission into a laminated composite cylindrical shell

    NASA Technical Reports Server (NTRS)

    Koval, L. R.

    1980-01-01

    In the context of the transmission of airborne noise into an aircraft fuselage, a mathematical model is presented for the transmission of an oblique plane sound wave into a laminated composite circular cylindrical shell. Numerical results are obtained for geometry typical of a narrow-bodied jet transport. Results indicate that from the viewpoint of noise attenuation on laminated composite shell does not appear to offer any significant advantage over an aluminum shell. However, the transmission loss of a laminated composite shell is sensitive to the orientation of the fibers and this suggests the possibility of using a laminated composite shell to tailor the noise attenuation characteristics to meet a specific need.

  2. The cylindrical δ-potential and the Dirac equation

    NASA Astrophysics Data System (ADS)

    Loewe, M.; Marquez, F.; Zamora, R.

    2012-11-01

    In this paper, we discuss the Dirac equation in the presence of an attractive cylindrical δ-shell potential V(ρ) = -aδ(ρ - ρ0), where ρ is the radial coordinate and a > 0. We present a detailed discussion on the boundary conditions the wavefunction has to satisfy when crossing the support of the potential, proceeding then to explore the dependence of the ground state on the parameter a, analyzing the occurrence of supercritical effects. We also apply the Foldy-Wouthuysen transformation, discussing the non-relativistic limit of this problem.

  3. Buckling of circular cylindrical shells under dynamically applied axial loads

    NASA Technical Reports Server (NTRS)

    Tulk, J. D.

    1972-01-01

    A theoretical and experimental study was made of the buckling characteristics of perfect and imperfect circular cylindrical shells subjected to dynamic axial loading. Experimental data included dynamic buckling loads (124 data points), high speed photographs of buckling mode shapes and observations of the dynamic stability of shells subjected to rapidly applied sub-critical loads. A mathematical model was developed to describe the dynamic behavior of perfect and imperfect shells. This model was based on the Donnell-Von Karman compatibility and equilibrium equations and had a wall deflection function incorporating five separate modes of deflection. Close agreement between theory and experiment was found for both dynamic buckling strength and buckling mode shapes.

  4. Rotating cylindrical wormholes: a no-go theorem

    NASA Astrophysics Data System (ADS)

    Bronnikov, K. A.

    2016-02-01

    The existing solutions to the Einstein equations describing rotating cylindrical wormholes are not asymptotically flat and therefore cannot describe wormhole entrances as local objects in our Universe. To overcome this difficulty, flat asymptotic regions are added to wormhole solutions by matching them at some surfaces ∑- and ∑+. It is shown, however, that if the wormhole solution is obtained for scalar fields with arbitrary potentials, possibly interacting with an azimuthal electric or magnetic field, then the matter content of one or both thin shells appearing on ∑- and ∑+ violate the Null Energy Condition. Thus exotic matter is still necessary for obtaining a twice asymptotically flat wormhole.

  5. Finite-amplitude waves in cylindrical lined ducts

    NASA Technical Reports Server (NTRS)

    Nayfeh, A. H.; Tsai, M.-S.

    1974-01-01

    A second-order uniformly valid expansion is obtained for nonlinear waves propagating in a cylindrical duct lined with a point-reacting acoustic material that consists of a porous sheet followed by honey-comb cavities and backed by the impervious walls of the duct. The effect of the liner is taken into account by coupling the waves in the duct with those in the liner. As in the two-dimensional case, the nonlinearity increases the attenuation rate at all frequencies except in narrow bandwidths around the resonant frequencies, irrespective of the geometrical dimensions of the liner or the acoustic properties of the porous sheet.

  6. Infrared cylindrical cloak in nanosphere dispersed liquid crystal metamaterial.

    PubMed

    Pawlik, G; Tarnowski, K; Walasik, W; Mitus, A C; Khoo, I C

    2012-06-01

    We present a design of an infrared cylindrical cloak using nanosphere dispersed nematic liquid crystal (NLC) metamaterial following the approach of Smith's group [Science 314, 977 (2006)]. Cloaking conditions require spatial distribution of liquid crystal birefringence with constant extraordinary index of refraction and radially dependent ordinary index of refraction. An approximate analytical formula for the latter is derived. Finite element (FE) simulations confirm the cloaking effect. Owing to the tunable birefringence of the liquid crystal component, such cloaking material offers the interesting possibilities of real-time control of invisibility. The possibility of experimental realization is briefly discussed. PMID:22660049

  7. Axial jet mixing of ethanol in cylindrical containers during weightlessness

    NASA Technical Reports Server (NTRS)

    Aydelott, J. C.

    1979-01-01

    An experimental program was conducted to examine the liquid flow patterns that result from the axial jet mixing of ethanol in 10-centimeter-diameter cylindrical tanks in weightlessness. A convex hemispherically ended tank and two Centaur liquid-hydrogen-tank models were used for the study. Four distinct liquid flow patterns were observed to be a function of the tank geometry, the liquid-jet velocity, the volume of liquid in the tank, and the location of the tube from which the liquid jet exited.

  8. Apparatus for scanning the surface of a cylindrical body

    NASA Technical Reports Server (NTRS)

    Nakich, R. B.; Woodbury, R. C. (Inventor)

    1974-01-01

    A laser scanning system for providing a two-dimensional display of a cylindrical surface, such as to display striae of a fired bullet is described. The cylinder is scanned along its axis by vibrating one mirror in the laser beam path, and is scanned in a direction normal to its axis by vibrating a second mirror in a direction normal to the first or by rotating the bullet. Scan control signals are adjusted in phase to produce a synchronized display of a video signal obtained from detection of scattered light from the surface thus scanned by a laser beam.

  9. Infinitesimal structure of inverse pinch effect cylindrical MHD shocks

    SciTech Connect

    Baty, Roy S; Stanescu, Dan; Tucker, Don H

    2008-01-01

    Nonstandard analysis is used to derive the relationships between the jump functions for density, pressure, velocity and magnetic field within a diverging cylindrical magnetohydrodynamic shock caused by the inverse pinch effect. The shock is assumed to have infinitesimal thickness. The obtained relationships allow explicit numerical constructions of the shock structure once the variation in one variable, here chosen to be the density, is specified. The shapes thus constructed offer additional insight into the physics of such shock waves from a perspective which would be extremely difficult to investigate experimentally.

  10. Three-Dimensional Prints with Pinned Cylindrical Lens Arrays

    NASA Astrophysics Data System (ADS)

    Yasuda, Shin; Shimizu, Keishi

    2013-09-01

    An application of pinned cylindrical lens arrays (CLAs) reported in Opt. Rev. 19 (2012) 287 to three-dimensional prints is presented for the first time. This lens fabrication method features the easy control of the pitch and radius of curvature of the lens arrays by taking advantage of the pinning effect that the partition walls created on a polymeric substrate by scratching with a cutter blade prevent the ultraviolet curable polymer dispensed between the walls from spreading. It is demonstrated in this paper that a three-dimensional print was realized successfully with the pinned CLA fabricated with our method.

  11. Cylindrical plasmas generated by an annular beam of ultraviolet light

    SciTech Connect

    Thomas, D. M.; Allen, J. E.

    2015-07-15

    We investigate a cylindrical plasma system with ionization, by an annular beam of ultraviolet light, taking place only in the cylinder's outer region. In the steady state, both the outer and inner regions contain a plasma, with that in the inner region being uniform and field-free. At the interface between the two regions, there is an infinitesimal jump in ion density, the magnitude approaching zero in the quasi-neutral (λ{sub D} → 0) limit. The system offers the possibility of producing a uniform stationary plasma in the laboratory, hitherto obtained only with thermally produced alkali plasmas.

  12. Optimization of multilayer cylindrical cloaks using genetic algorithms and NEWUOA

    NASA Astrophysics Data System (ADS)

    Sakr, Ahmed A.; Abdelmageed, Alaa K.

    2016-06-01

    The problem of minimizing the scattering from a multilayer cylindrical cloak is studied. Both TM and TE polarizations are considered. A two-stage optimization procedure using genetic algorithms and NEWUOA (new unconstrained optimization algorithm) is adopted for realizing the cloak using homogeneous isotropic layers. The layers are arranged such that they follow a repeated pattern of alternating DPS and DNG materials. The results show that a good level of invisibility can be realized using a reasonable number of layers. Maintaining the cloak performance over a finite range of frequencies without sacrificing the level of invisibility is achieved.

  13. Spectrum of resistive MHD modes in cylindrical plasmas

    SciTech Connect

    Ryu, C.M.; Grimm, R.C.

    1983-07-01

    A numerical study of the normal modes of a compressible resistive MHD fluid in cylindrical geometry is presented. Resistivity resolves the shear Alfven and slow magnetosonic continua of ideal MHD into discrete spectra and gives rise to heavily damped modes whose frequencies lie on specific lines in the complex plane. Fast magnetosonic waves are less affected but are also damped. Overstable modes arise from the shear Alfven spectrum. The stabilizing effect of favorable average curvature is shown. Eigenfunctions illustrating the nature of typical normal modes are displayed.

  14. Polar POLICRYPS diffractive structures generate cylindrical vector beams

    SciTech Connect

    Alj, Domenico; Caputo, Roberto Umeton, Cesare; Paladugu, Sathyanarayana; Volpe, Giovanni

    2015-11-16

    Local shaping of the polarization state of a light beam is appealing for a number of applications. This can be achieved by employing devices containing birefringent materials. In this article, we present one such enables converting a uniformly circularly polarized beam into a cylindrical vector beam (CVB). This device has been fabricated by exploiting the POLICRYPS (POlymer-LIquid CRYstals-Polymer-Slices) photocuring technique. It is a liquid-crystal-based optical diffraction grating featuring polar symmetry of the director alignment. We have characterized the resulting CVB profile and polarization for the cases of left and right circularly polarized incoming beams.

  15. Color preference in red-green dichromats.

    PubMed

    Álvaro, Leticia; Moreira, Humberto; Lillo, Julio; Franklin, Anna

    2015-07-28

    Around 2% of males have red-green dichromacy, which is a genetic disorder of color vision where one type of cone photoreceptor is missing. Here we investigate the color preferences of dichromats. We aim (i) to establish whether the systematic and reliable color preferences of normal trichromatic observers (e.g., preference maximum at blue, minimum at yellow-green) are affected by dichromacy and (ii) to test theories of color preference with a dichromatic sample. Dichromat and normal trichromat observers named and rated how much they liked saturated, light, dark, and focal colors twice. Trichromats had the expected pattern of preference. Dichromats had a reliable pattern of preference that was different to trichromats, with a preference maximum rather than minimum at yellow and a much weaker preference for blue than trichromats. Color preference was more affected in observers who lacked the cone type sensitive to long wavelengths (protanopes) than in those who lacked the cone type sensitive to medium wavelengths (deuteranopes). Trichromats' preferences were summarized effectively in terms of cone-contrast between color and background, and yellow-blue cone-contrast could account for dichromats' pattern of preference, with some evidence for residual red-green activity in deuteranopes' preference. Dichromats' color naming also could account for their color preferences, with colors named more accurately and quickly being more preferred. This relationship between color naming and preference also was present for trichromat males but not females. Overall, the findings provide novel evidence on how dichromats experience color, advance the understanding of why humans like some colors more than others, and have implications for general theories of aesthetics. PMID:26170287

  16. Color preference in red–green dichromats

    PubMed Central

    Álvaro, Leticia; Moreira, Humberto; Lillo, Julio; Franklin, Anna

    2015-01-01

    Around 2% of males have red–green dichromacy, which is a genetic disorder of color vision where one type of cone photoreceptor is missing. Here we investigate the color preferences of dichromats. We aim (i) to establish whether the systematic and reliable color preferences of normal trichromatic observers (e.g., preference maximum at blue, minimum at yellow-green) are affected by dichromacy and (ii) to test theories of color preference with a dichromatic sample. Dichromat and normal trichromat observers named and rated how much they liked saturated, light, dark, and focal colors twice. Trichromats had the expected pattern of preference. Dichromats had a reliable pattern of preference that was different to trichromats, with a preference maximum rather than minimum at yellow and a much weaker preference for blue than trichromats. Color preference was more affected in observers who lacked the cone type sensitive to long wavelengths (protanopes) than in those who lacked the cone type sensitive to medium wavelengths (deuteranopes). Trichromats’ preferences were summarized effectively in terms of cone-contrast between color and background, and yellow-blue cone-contrast could account for dichromats’ pattern of preference, with some evidence for residual red–green activity in deuteranopes’ preference. Dichromats’ color naming also could account for their color preferences, with colors named more accurately and quickly being more preferred. This relationship between color naming and preference also was present for trichromat males but not females. Overall, the findings provide novel evidence on how dichromats experience color, advance the understanding of why humans like some colors more than others, and have implications for general theories of aesthetics. PMID:26170287

  17. Bumblebee preference for symmetrical flowers.

    PubMed

    Møller, A P

    1995-03-14

    Fluctuating asymmetry, which represents small random deviations from otherwise bilateral symmetry, is a measure of the phenotypic quality of individuals indicating the ability of controlled development under given environmental and genetic conditions. I tested whether floral symmetry reliably reflects phenotypic quality measured in terms of pollinator rewards and whether pollinators respond to floral symmetry in a series of observations and experiments on Epilobium angustifolium (Onagraceae). Lower petal asymmetry was negatively related to mean lower petal length, whereas asymmetry in leaf width was positively related to mean leaf width. Flowers visited by bumblebees were larger and more symmetrical than the nearest neighboring flower. This relationship between pollinator preference for large and symmetrical flowers was demonstrated to be causal in experiments in which the lower petals were manipulated symmetrically or asymmetrically. Nectar production was larger in symmetrical flowers, and this may explain the bumblebee preference for flower symmetry. Floral symmetry therefore reliably reflects nectar production and hence enhances pollen transport. Extensive embryo abortion has been documented in E. angustifolium and other outcrossing plant species. Floral fluctuating asymmetry, which reflects general developmental homeostasis, may explain such developmental selection in these plants. PMID:11607519

  18. The shape of female mating preferences

    PubMed Central

    Ritchie, Michael G.

    1996-01-01

    The “shape” of a female mating preference is the relationship between a male trait and the probability of acceptance as a mating partner. The shape of preferences is important in many models of sexual selection, mate recognition, communication, and speciation, yet it has rarely been measured precisely. Here I examine preference shape for male calling song in a bushcricket (katydid). Preferences change dramatically between races of a species, from strongly directional to broadly stabilizing (but with a net directional effect). Preference shape generally matches the distribution of the male trait. This is compatible with a coevolutionary model of signal-preference evolution, although it does not rule out an alternative model, sensory exploitation. Preference shapes are shown to be genetic in origin. PMID:8962104

  19. A Molecular and Morphological Reassessment of Diademaceae

    PubMed Central

    Ariyawansa, Hiran A.; Tibpromma, Saowaluck; Kang, Ji-Chuan; Hyde, Kevin D.

    2014-01-01

    We revisit the family Diademaceae based on available sequence data and morphology. Diademaceae is characterized by ascomata opening with a flat circular lid and fissitunicate, short orbicular frequently cylindrical, pedicellate asci. Ascospores are frequently circular in section but narrowing to one end with three or more transverse septa, without longitudinal septa, and mostly with a thick sheath. In recent treatments Clathrospora, Comoclathris, Diadema, Diademosa, and Graphyllium were placed in the family. Following molecular and morphological study, Clathrospora, Comoclathris, and Diademosa, are excluded from the family and referred to Pleosporaceae. Graphyllium is excluded from Diademaceae, based on hysterothecium-like ascomata with a longitudinal opening, and tentatively placed in Hysteriaceae with uncertainty; species with hysterothecia have now been accommodated in at least five families. The study accepts only Diadema in the family. The status of Diademaceae as a distinct family, based on the ascomata opening by a flat circular lid, is thought to be doubtful. Fresh collections of Diadema are needed for epitypification and to obtain sequence data to establish if this is a well-resolved family. PMID:24526916

  20. A molecular and morphological reassessment of Diademaceae.

    PubMed

    Ariyawansa, Hiran A; Phookamsak, Rungtiwa; Tibpromma, Saowaluck; Kang, Ji-Chuan; Hyde, Kevin D

    2014-01-01

    We revisit the family Diademaceae based on available sequence data and morphology. Diademaceae is characterized by ascomata opening with a flat circular lid and fissitunicate, short orbicular frequently cylindrical, pedicellate asci. Ascospores are frequently circular in section but narrowing to one end with three or more transverse septa, without longitudinal septa, and mostly with a thick sheath. In recent treatments Clathrospora, Comoclathris, Diadema, Diademosa, and Graphyllium were placed in the family. Following molecular and morphological study, Clathrospora, Comoclathris, and Diademosa, are excluded from the family and referred to Pleosporaceae. Graphyllium is excluded from Diademaceae, based on hysterothecium-like ascomata with a longitudinal opening, and tentatively placed in Hysteriaceae with uncertainty; species with hysterothecia have now been accommodated in at least five families. The study accepts only Diadema in the family. The status of Diademaceae as a distinct family, based on the ascomata opening by a flat circular lid, is thought to be doubtful. Fresh collections of Diadema are needed for epitypification and to obtain sequence data to establish if this is a well-resolved family. PMID:24526916

  1. Pathways of cylindrical orientations in PS-b-P4VP diblock copolymer thin films upon solvent vapor annealing.

    PubMed

    Gowd, E Bhoje; Koga, Tadanori; Endoh, Maya K; Kumar, Kamlesh; Stamm, Manfred

    2014-10-21

    The orientation changes of perpendicular cylindrical microdomains in polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) thin films upon annealing in different solvent vapors were investigated by in situ grazing incidence small-angle X-ray scattering (GISAXS) and ex situ scanning force microscopy (SFM). The swelling of P4VP perpendicular cylinders (C⊥) in chloroform, a non-selective solvent vapor, leads to the reorientation to in-plane cylinders through a disordered state in a particular kinetic pathway in the phase diagram upon drying. On the other hand, the swelling of the P4VP perpendicular cylinders in a selective solvent vapor (i.e., 1,4-dioxane) induces a morphological transition from cylindrical to ellipsoidal as a transient structure to spherical microdomains; subsequent solvent evaporation resulted in shrinkage of the matrix in the vertical direction, merging the ellipsoidal domains into the perpendicularly aligned cylinders. In this paper, we have discussed the mechanism based on the selectivity of the solvent to the constituting blocks that is mainly responsible for the orientation changes. PMID:25142254

  2. Stabilizing Surfactant Templated Cylindrical Mesopores in Polymer and Carbon Films through Composite Formation with Silica Reinforcement

    SciTech Connect

    Song, Lingyan; Feng, Dan; Lee, Hae-Jeong; Wang, Chengqing; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D.

    2010-10-22

    A facile approach to maintain the periodic mesostructure of cylindrical pores in polymer-resin and carbon films after thermal template removal is explored through the reactive coassembly of resol (carbon precursor) and tetraethylorthosilicate (silica precursor) with triblock copolymer Pluronic F127. Without silica, a low porosity, disordered film is formed after pyrolysis despite the presence of an ordered mesostructure prior to template removal. However for silica concentration greater than 25 wt %, pyrolysis at 350 C yields a mesoporous silica-polymer film with well-defined pore mesostructure. These films remain well ordered upon carbonization at 800 C. In addition to the mesostructural stability, the addition of silica to the matrix impacts other morphological characteristics. For example, the average pore size and porosity of the films increase from 3.2 to 7.5 nm and 12 to 45%, respectively, as the concentration of silica in the wall matrix increases from 0 to 32 wt %. The improved thermal stability of the ordered mesostructure with the addition of silica to the matrix is attributed to the reinforcement of the mechanical properties leading to resistance to stress induced collapse of the mesostructure during template removal.

  3. Global optimization method for combined spherical-cylindrical wrapping in musculoskeletal upper limb modelling.

    PubMed

    Audenaert, A; Audenaert, E

    2008-10-01

    In musculoskeletal modelling, many muscles cannot be represented as straight lines from origin to insertion because the bony and musculotendinous morphology of neighboring structures causes them to wrap. The majority of these passive structures can be adequately described as simple geometric shapes such as spheres and cylinders. Techniques for describing smooth muscle paths around multiple obstacles have been developed for modelling use. Until now obstacle-set methods have combined the path of single structures. This does not analytically define the shortest smooth path around multiple objects. When a sphere is included in a multiple-object wrapping algorithm, muscle paths around that sphere are restricted to a bundle of planes containing the sphere center. This assumed restriction can compromise the iterative process for finding the true shortest muscle path that satisfies all restrictions of a smooth path. This can cause model instability. The new method involves the determination of the shortest smooth muscle path in a spherical and cylindrical wrapping algorithm. A typical example is musculoskeletal modelling of the upper limb, where the muscle fibers have to wrap over this combination of obstacles. PMID:18606476

  4. Topography-Correlated Confocal Raman Microscopy with Cylindrical Vector Beams for Probing Nanoscale Structural Order.

    PubMed

    Wang, Xiao; Broch, Katharina; Scholz, Reinhard; Schreiber, Frank; Meixner, Alfred J; Zhang, Dai

    2014-04-01

    Cylindrical vector beams, such as radially or azimuthally polarized doughnut beams, are combined with topography studies of pentacene thin films, allowing us to correlate Raman spectroscopy with intermolecular interactions depending on the particular pentacene polymorph. Polarization-dependent Raman spectra of the C-H bending vibrations are resolved layer by layer within a thin film of ∼20 nm thickness. The variation of the Raman peak positions indicates changes in the molecular orientation and in the local environment at different heights of the pentacene film. With the assistance of a theoretical model based on harmonic oscillator and perturbation theory, our method reveals the local structural order and the polymorph at different locations within the same pentacene thin film, depending mainly on its thickness. In good agreement with the crystallographic structures reported in the literature, our observations demonstrate that the first few monolayers grown in a structure are closer to the thin-film phase, but for larger film thicknesses, the morphology evolves toward the crystal-bulk phase with a larger tilting angle of the pentacene molecules against the substrate normal. PMID:26274447

  5. Heat transfer during quenching of modified and unmodified gravity die-cast A357 cylindrical bars

    NASA Astrophysics Data System (ADS)

    Prabhu, K. N.; Hemanna, P.

    2006-06-01

    Heat transfer during quenching of chill-cast modified and unmodified A357 Al-Si alloy was examined using a computer-aided cooling curve analysis. Water at 60 °C and a vegetable oil (palm oil) were used as quench media. The measured temperatures inside cylindrical probes of the A357 alloy were used as inputs in an inverse heat-conduction model to estimate heat flux transients at the probe/quenchant interface and the surface temperature of the probe in contact with the quench medium. It was observed that modified alloy probes yielded higher cooling rates and heat flux transients. The investigation clearly showed that the heat transfer during quenching depends on the casting history. The increase in the cooling rate and peak heat flux was attributed to the increase in the thermal conductivity of the material on modification melt treatment owing to the change in silicon morphology. Fine and fibrous silicon particles in modified A357 probes increase the conductance of the probe resulting in higher heat transfer rates. This was confirmed by measuring the electrical conductivity of modified samples, which were found to be higher than those of unmodified samples. The ultrasound velocity in the probes decreased on modification.

  6. Musical Preferences are Linked to Cognitive Styles

    PubMed Central

    Greenberg, David M.; Baron-Cohen, Simon; Stillwell, David J.; Kosinski, Michal; Rentfrow, Peter J.

    2015-01-01

    Why do we like the music we do? Research has shown that musical preferences and personality are linked, yet little is known about other influences on preferences such as cognitive styles. To address this gap, we investigated how individual differences in musical preferences are explained by the empathizing-systemizing (E-S) theory. Study 1 examined the links between empathy and musical preferences across four samples. By reporting their preferential reactions to musical stimuli, samples 1 and 2 (Ns = 2,178 and 891) indicated their preferences for music from 26 different genres, and samples 3 and 4 (Ns = 747 and 320) indicated their preferences for music from only a single genre (rock or jazz). Results across samples showed that empathy levels are linked to preferences even within genres and account for significant proportions of variance in preferences over and above personality traits for various music-preference dimensions. Study 2 (N = 353) replicated and extended these findings by investigating how musical preferences are differentiated by E-S cognitive styles (i.e., ‘brain types’). Those who are type E (bias towards empathizing) preferred music on the Mellow dimension (R&B/soul, adult contemporary, soft rock genres) compared to type S (bias towards systemizing) who preferred music on the Intense dimension (punk, heavy metal, and hard rock). Analyses of fine-grained psychological and sonic attributes in the music revealed that type E individuals preferred music that featured low arousal (gentle, warm, and sensual attributes), negative valence (depressing and sad), and emotional depth (poetic, relaxing, and thoughtful), while type S preferred music that featured high arousal (strong, tense, and thrilling), and aspects of positive valence (animated) and cerebral depth (complexity). The application of these findings for clinicians, interventions, and those on the autism spectrum (largely type S or extreme type S) are discussed. PMID:26200656

  7. Musical Preferences are Linked to Cognitive Styles.

    PubMed

    Greenberg, David M; Baron-Cohen, Simon; Stillwell, David J; Kosinski, Michal; Rentfrow, Peter J

    2015-01-01

    Why do we like the music we do? Research has shown that musical preferences and personality are linked, yet little is known about other influences on preferences such as cognitive styles. To address this gap, we investigated how individual differences in musical preferences are explained by the empathizing-systemizing (E-S) theory. Study 1 examined the links between empathy and musical preferences across four samples. By reporting their preferential reactions to musical stimuli, samples 1 and 2 (Ns = 2,178 and 891) indicated their preferences for music from 26 different genres, and samples 3 and 4 (Ns = 747 and 320) indicated their preferences for music from only a single genre (rock or jazz). Results across samples showed that empathy levels are linked to preferences even within genres and account for significant proportions of variance in preferences over and above personality traits for various music-preference dimensions. Study 2 (N = 353) replicated and extended these findings by investigating how musical preferences are differentiated by E-S cognitive styles (i.e., 'brain types'). Those who are type E (bias towards empathizing) preferred music on the Mellow dimension (R&B/soul, adult contemporary, soft rock genres) compared to type S (bias towards systemizing) who preferred music on the Intense dimension (punk, heavy metal, and hard rock). Analyses of fine-grained psychological and sonic attributes in the music revealed that type E individuals preferred music that featured low arousal (gentle, warm, and sensual attributes), negative valence (depressing and sad), and emotional depth (poetic, relaxing, and thoughtful), while type S preferred music that featured high arousal (strong, tense, and thrilling), and aspects of positive valence (animated) and cerebral depth (complexity). The application of these findings for clinicians, interventions, and those on the autism spectrum (largely type S or extreme type S) are discussed. PMID:26200656

  8. Ultrasound cylindrical phased array for transoesophageal thermal therapy: initial studies

    NASA Astrophysics Data System (ADS)

    Melodelima, David; Lafon, Cyril; Prat, Frederic; Birer, Alain; Cathignol, Dominique

    2002-12-01

    This work was undertaken to investigate the feasibility of constructing a cylindrical phased array composed of 64 elements spread around the periphery (OD 10.6 mm) for transoesophageal ultrasound thermotherapy. The underlying operating principle of this applicator is to rotate a plane ultrasound beam electronically. For this purpose, eight adjacent transducers were successively excited with appropriate delay times so as to generate a plane wave. The exposure direction was changed by exciting a different set of eight elements. For these feasibility studies, we used a cylindrical prototype (OD 10.6 mm) composed of 16 elementary transducers distributed over a quarter of the cylinder, all operating at 4.55 MHz. The active part was mechanically reinforced by a rigid damper structure behind the transducers. It was shown that an ultrasound field similar to that emitted by a plane transducer could be generated. Ex vivo experiments on pig's liver demonstrated that the ultrasound beam could be accurately rotated to generate sector-based lesions to a suitable depth (up to 19 mm). Throughout these experiments, exposures lasting 20 s were delivered at an acoustic intensity of 17 W cm-2. By varying the power from exposure to exposure, the depth of the lesion at different angles could be controlled.

  9. Cylindrical acoustical holography applied to full-scale jet noise.

    PubMed

    Wall, Alan T; Gee, Kent L; Neilsen, Tracianne B; Krueger, David W; James, Michael M

    2014-09-01

    Near-field acoustical holography methods are used to predict sound radiation from an engine installed on a high-performance military fighter aircraft. Cylindrical holography techniques are an efficient approach to measure the large and complex sound fields produced by full-scale jets. It is shown that a ground-based, one-dimensional array of microphones can be used in conjunction with a cylindrical wave function field representation to provide a holographic reconstruction of the radiated sound field at low frequencies. In the current work, partial field decomposition methods and numerical extrapolation of data beyond the boundaries of the hologram aperture are required prior to holographic projection. Predicted jet noise source distributions and directionality are shown for four frequencies between 63 and 250 Hz. It is shown that the source distribution narrows and moves upstream, and that radiation directionality shifts toward the forward direction, with increasing frequency. A double-lobe feature of full-scale jet radiation is also demonstrated. PMID:25190387

  10. Experimental fatigue life investigation of cylindrical thrust chambers

    NASA Technical Reports Server (NTRS)

    Quentmeyer, R. J.

    1977-01-01

    Twenty-two cylindrical test sections of a cylindrical rocket thrust chamber were fabricated and 21 of them were cycled to failure to explore the failure mechanisms, determine the effects of wall temperature on cyclic life, and to rank the material life characteristics for comparison with results from isothermal tests of 12 alloys at 538 C. Cylinder liners were fabricated from OFHC copper, Amzirc, and NAR1loy-Z. Tests were conducted at a chamber pressure of 4.14 MW/sq m using hydrogen-oxygen propellants at an oxidant-fuel ratio of 6.0, which resulted in an average throat heat flux of 54 MW/sq m. The cylinders were cooled with liquid hydrogen at an average rate of 0.91 Kg/sec. All failures were characterized by a thinning of the cooling channel wall at the centerline and eventual failure by tensile rupture. Cyclic life rankings of the materials based on temperature do not agree with published rankings based on uniaxial, isothermal strain tests.

  11. High-speed cylindrical collapse of two perfect fluids

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Ahmad, Zahid

    2007-09-01

    In this paper, the study of the gravitational collapse of cylindrically distributed two perfect fluid system has been carried out. It is assumed that the collapsing speeds of the two fluids are very large. We explore this condition by using the high-speed approximation scheme. There arise two cases, i.e., bounded and vanishing of the ratios of the pressures with densities of two fluids given by c s , d s . It is shown that the high-speed approximation scheme breaks down by non-zero pressures p 1, p 2 when c s , d s are bounded below by some positive constants. The failure of the high-speed approximation scheme at some particular time of the gravitational collapse suggests the uncertainty on the evolution at and after this time. In the bounded case, the naked singularity formation seems to be impossible for the cylindrical two perfect fluids. For the vanishing case, if a linear equation of state is used, the high-speed collapse does not break down by the effects of the pressures and consequently a naked singularity forms. This work provides the generalisation of the results already given by Nakao and Morisawa (Prog Theor Phys 113:73, 2005) for the perfect fluid.

  12. Transient Eddy Current Response Due to a Conductive Cylindrical Rod

    NASA Astrophysics Data System (ADS)

    Fu, Fangwei; Bowler, J. R.

    2007-03-01

    Transient eddy current test systems have been developed for the inspection of aircraft structures and for oil and gas pipelines. This work is supported by theoretical developments in which transient fields and time domain signals are determined for the geometry of interest. However most of the models to date have been aimed at structures that are planar, relatively little attention being paid to the corresponding problems in cylindrical geometries. In order to rectify this deficiency, we have examined theoretically the transient probe signal response due to a cylindrical conductive rod excited by an encircling coil. The transient fields can be calculated from a Fourier transform of the frequency domain solutions for infinite rods or tubes but, as with planar structures, we have found that it is better to use series solutions in the time domain since these provide more accurate and flexible representations of transient fields. Two types of series are used; one which converges faster at short times and one which converges faster at longer times. Calculations using these series show that they are in mutual agreement and agree with results computed using the fast Fourier transform.

  13. Coulomb Crystals in Cylindrical Dusty Plasmas under Gravity/Microgravity

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazuo; Totsuji, Hiroo; Adachi, Satoshi

    2014-10-01

    Coulomb crystals of dusty plasmas have been studied under microgravity with utilities boarding on the International Space Station in a joint Russian/German research project. Dynamics of the Coulomb crystals in cylindrical plasmas is investigated with the apparatus of PK-4 being launched till the end of 2014. A science team in Japan studied the cylindrical dusty plasmas to contribute to the project with the PK-4J modified original for microgravity experiments of parabolic flights in Japan. In the experiments, the dust particles distributed at the off-centered position close to the bottom in balancing of gravity. Under microgravity, they changed the distribution and formed a Coulomb crystal around the center axis in the plasmas. Several particles arranged in a line parallel to the axis, and the lines piled up to a bundle. Spatial distribution of the dust particles affects on plasma parameters of ion density and electron temperature. Structures of the Coulomb crystals connected to the parameters are discussed. The present study were supported by JAXA and Diamond Air Service.

  14. On the optimal pretensioning of cylindrical and spherical pressure vessels

    SciTech Connect

    Kalamkarov, A.L.; Drozdov, A.D.

    1995-11-01

    Filament winding of pressure vessels and pipes is always realized with some pretensioning, and some external loads may be applied. It is important to determine such an optimal preload regime that ensures the maximum load-carrying capacity of the vessel subject to internal pressure. In the present study, the optimal preload distribution is analyzed in the filament winding fabrication of the cylindrical or spherical pressure vessels that are treated as growing elastic solids subjected to aging. In the case of cylindrical vessels, the dependence of the optimal preload intensity versus the polar radius is obtained for both nonaging and aging material of the fibers. In the case of spherical pressure vessels, the optimal regime of internal pressure applied during the winding process is obtained. The optimal loading of a spherical vessel at both infinitesimal and finite strains is analyzed. The new solutions obtained and the recommendations formulated are of a special practical importance for the optimal design and fabrication of the composite pressure vessels and pipes.

  15. Residual Stress Measurements of Explosively Clad Cylindrical Pressure Vessels

    SciTech Connect

    Taylor, Douglas J; Watkins, Thomas R; Hubbard, Camden R; Hill, M. R.; Meith, W. A.

    2012-01-01

    Tantalum refractory liners were explosively clad into cylindrical pressure vessels, some of which had been previously autofrettaged. Using explosive cladding, the refractory liner formed a metallurgical bond with the steel of the pressure vessel at a cost of induced strain. Two techniques were employed to determine the residual stress state of the clad steel cylinders: neutron diffraction and mechanical slitting. Neutron diffraction is typically nondestructive; however, due to attenuation along the beam path, the cylinders had to be sectioned into rings that were nominally 25 mm thick. Slitting is a destructive method, requiring the sectioning of the cylindrical samples. Both techniques provided triaxial stress data and useful information on the effects of explosive cladding. The stress profiles in the hoop and radial directions were similar for an autofrettaged, nonclad vessel and a clad, nonautofrettaged vessel. The stress profiles in the axial direction appeared to be different. Further, the data suggested that residual stresses from the autofrettage and explosive cladding processes were not additive, in part due to evidence of reverse yielding. The residual stress data are presented, compared and discussed.

  16. The magnetic field of a permanent hollow cylindrical magnet

    NASA Astrophysics Data System (ADS)

    Reich, Felix A.; Stahn, Oliver; Müller, Wolfgang H.

    2015-12-01

    Based on the rational version of Muc(AXWELL)'s equations according to Tuc(RUESDELL) and Tuc(OUPIN) or KOVETZ, cf. (Kovetz in Electromagnetic theory, Oxford University Press, Oxford, 2000; Truesdell and Toupin in Handbuch der Physik, Bd. III/1, Springer, Berlin, pp 226-793; appendix, pp 794-858, 2000), we present, for stationary processes, a closed-form solution for the magnetic flux density of a hollow cylindrical magnet. Its magnetization is constant in axial direction. We consider Muc(AXWELL)'s equations in regular and singular points that are obtained by rational electrodynamics, adapted to stationary processes. The magnetic flux density is calculated analytically by means of a vector potential. We obtain a solution in terms of complete elliptic integrals. Therefore, numerical evaluation can be performed in a computationally efficient manner. The solution is written in dimensionless form and can easily be applied to cylinders of arbitrary shape. The relation between the magnetic flux density and the magnetic field is linear, and an explicit relation for the field is presented. With a slight modification the result can be used to obtain the field of a solid cylindrical magnet. The mathematical structure of the solution and, in particular, singularities are discussed.

  17. Free Vibration Analysis of Cylindrical Tanks Partially Filled with Liquid

    NASA Astrophysics Data System (ADS)

    Gonçalves, P. B.; Ramos, N. R. S. S.

    1996-08-01

    A simple but effective modal solution based on the underlying ideas of the hierarchical finite element method is presented for evaluating the free vibration characteristics of vertical, thin, circular, cylindrical shells, partially or completely filled with liquid and subjected to any variationally consistent set of boundary conditions on the lower and upper boundaries. Effects of static liquid pressure, in-plane inertias and liquid free surface motions are taken into account. The solution of the shell problem is obtained through a procedure in which Sander's shell equations are transformed into a new system of first order ordinary differential equations which are solved by the Galerkin error-minimization procedure. The system variables are those quantities which appear in the boundary conditions on a rotationally symmetric edge of a cylindrical shell. The liquid is taken as non-viscous and incompressible, and the coupling between the deformable shell and this medium is taken into account. The solution for the liquid velocity potential is assumed as a sum of two sets of linear combinations of suitable harmonic functions which satisfy Laplace equation and the relevant boundary conditions. This procedure leads to a determinantal equation for the determination of the shell and liquid natural frequencies and the associated mode shapes. Application of the method to a few selected cases and comparisons of the numerical results with those obtained by other theories and from experiments are found to be good and demonstrate the effectiveness and accuracy of the present methodology.

  18. Array gain for a cylindrical array with baffle scatter effects.

    PubMed

    Bertilone, Derek C; Killeen, Damien S; Bao, Chaoying

    2007-11-01

    Cylindrical arrays used in sonar for passive underwater surveillance often have sensors surrounding a cylindrical metal baffle. In some operational sonars, the phones in each stave (i.e., each line of phones aligned with the cylinder axis) are hardwired together so that the array is equivalent to a baffled circular array of directional elements, where each element corresponds to a line array of omnidirectional phones steered to broadside. In this paper a model is introduced for computing the array gain of such an array at high frequencies, which incorporates baffle scatter using infinite, rigid cylinder scattering theory, and with ambient noise described by an angular spectral density function. In practice the phones are often offset from the baffle surface, and the acoustic field sampled by the staves is distorted at high frequencies due to interference between the incident and scattered fields. Examples are given to illustrate the resulting array gain degradation, using three noise distributions that are frequently used in sonar performance modeling: three-dimensional isotropic, two-dimensional isotropic, and surface dipole noise. PMID:18189560

  19. Experimental study of fluid flows in a precessing cylindrical annulus

    NASA Astrophysics Data System (ADS)

    Lin, Yufeng; Noir, Jerome; Jackson, Andrew

    2014-04-01

    The flow inside a precessing fluid cavity has been given particular attention since the end of the 19th century in geophysical and industrial contexts. The present study aims at shedding light on the underlying mechanism by which the flow inside a precessing cylindrical annulus transitions from laminar to multiple scale complex structures. We address this problem experimentally using ultrasonic Doppler velocimetry to diagnose the fluid velocity in a rotating and precessing cylindrical annulus. When precession is weak, the flow can be described as a superposition of forced inertial modes. Above a critical value of the precession rate, the forced flow couples with two free inertial modes satisfying triadic resonance conditions, leading to the classical growth and collapse. Using a Bayesian approach, we extract the wavenumber, frequency, growth rate, and amplitude of each mode involved in the instability. In some cases, we observe for the first time ever experimentally two pairs of free modes coexisting with the forced flow. At larger precession rates, we do not observe triadic resonance any more, instead we observe several harmonics whose frequencies are integer multiples of the rotation frequency.

  20. Explosion-Induced Implosions of Cylindrical Shell Structures

    NASA Astrophysics Data System (ADS)

    Ikeda, C. M.; Duncan, J. H.

    2010-11-01

    An experimental study of the explosion-induced implosion of cylindrical shell structures in a high-pressure water environment was performed. The shell structures are filled with air at atmospheric pressure and are placed in a large water-filled pressure vessel. The vessel is then pressurized to various levels P∞=αPc, where Pc is the natural implosion pressure of the model and α is a factor that ranges from 0.1 to 0.9. An explosive is then set off at various standoff distances, d, from the model center line, where d varies from R to 10R and R is the maximum radius of the explosion bubble. High-speed photography (27,000 fps) was used to observe the explosion and resulting shell structure implosion. High-frequency underwater blast sensors recorded dynamic pressure waves at 6 positions. The cylindrical models were made from aluminum (diameter D = 39.1 mm, wall thickness t = 0.89 mm, length L = 240 mm) and brass (D = 16.7 mm, t = 0.36 mm, L=152 mm) tubes. The pressure records are interpreted in light of the high-speed movies. It is found that the implosion is induced by two mechanisms: the shockwave generated by the explosion and the jet formed during the explosion-bubble collapse. Whether an implosion is caused by the shockwave or the jet depends on the maximum bubble diameter and the standoff distance.

  1. Cylindrical Liner Z-pinch Experiments on the MAGPIE Generator

    NASA Astrophysics Data System (ADS)

    Burdiak, Guy; Lebedev, Sergey V.; Harvey-Thompson, Adam J.; Swadling, George F.; Suzuki-Vidal, Francisco; Skidmore, Jonathan; Suttle, Lee; Khoory, Essa; Pickworth, Louisa; de Grouchy, Philip; Hall, Gareth N.; Bland, Simon N.; Weinwurm, Marcus; Chittenden, Jeremy P.

    2012-10-01

    Experimental data from gas-filled cylindrical liner z-pinch experiments is presented. The MAGPIE current (1.4 MA, 240 ns) is applied to a thin walled (80um) Al tube with a static gas-fill inside. The system is diagnosed axially using interferometry, optical streak photography and optical spectroscopy. We observe a series of cylindrically converging shock waves driven into the gas-fill from the inside liner surface. No bulk motion of the liner occurs. The timing of the shocks and their trajectories provide information on the shock launching mechanisms. This in turn allows a study of the response of the liner to the current pulse. Shock wave timing is compared to measurements of the liner resistance and optical images of the liner's outside surface. The system provides a useful, essentially 1D problem for testing MagLIF relevant MHD codes, particularly with regards to EOS, strength and resistivity models. This work may also be relevant to the study of shocks in astrophysical plasmas. The shocks launched into the gas radiatiate strongly; spatially resolved optical spectroscopy data and radial electron density profiles from interferometry images provide evidence for a radiative precursor ahead of the first shock. Instabilities are seen to develop in the downstream regions.

  2. Investigation of a scanned cylindrical ultrasound system for breast hyperthermia

    NASA Astrophysics Data System (ADS)

    Ju, Kuen-Cheng; Tseng, Li-Te; Chen, Yung-Yaw; Lin, Win-Li

    2006-02-01

    This paper investigates the feasibility of a scanned cylindrical ultrasound system for producing uniform heating from the central to the superficial portions of the breast or localized heating within the breast at a specific location. The proposed system consists of plane ultrasound transducer(s) mounted on a scanned cylindrical support. The breast was immersed in water and surrounded by this system during the treatment. The control parameters considered are the size of the transducer, the ultrasound frequency, the scan angle and the shifting distance between the axes of the breast and the system. Three-dimensional acoustical and thermal models were used to calculate the temperature distribution. Non-perfused phantom experiments were performed to verify the simulation results. Simulation results indicate that high frequency ultrasound could be used for the superficial heating, and the scan angle of the transducer could be varied to obtain an appropriate high temperature region to cover the desired treatment region. Low frequency ultrasound could be used for deep heating and the high temperature region could be moved by shifting the system. In addition, a combination of low and high frequency ultrasound could result in a portion treatment from the central to the superficial breast or an entire breast treatment. Good agreement was obtained between non-perfused experiments and simulation results. The findings of this study can be used to determine the effects of the control parameters of this system, as well as to select the optimal parameters for a specific treatment.

  3. Machine Tool User Cylindrical Die Rolling Performance Support System

    SciTech Connect

    Bohley, M.C.; Grothe, V.D.

    1998-08-06

    This project was initiated to provide the machine tool industry and the DOE a method for evaluating educating potential users about various aspects of the cylindrical die rolling process including: characteristics of the cylindrical die rolling processes, major productivity and material savings benefits, advantages for use in the fastener industry, production capabilities based on part parameters, and production capabilities based on machine specifications. AlliedSignal Federal Manufacturing and Technologies (ASFM and T) utilized data provided by Kinefac Corporation to develop an interactive performance support system. AlliedSignal developed one complete branch of the program and Kinefac will develop the remaining two branches. Macromedia Authorware version 3.5 and Microsoft Access version 7.0 were selected for development tools. These software tools maximize continued program development ease and program management with future machine technology advancements. Using this authoring tool and the external database resulted in development of a product that has many potential uses within the manufacturing industry. Source code for the product can be used as a template for other applications is reusable and can provide potential solutions to non-manufacturing needs. The final product will be released on CD-ROM.

  4. Cylindrical diffractive lenses recorded on PVA/AA photopolymers

    NASA Astrophysics Data System (ADS)

    Fernández, R.; Gallego, S.; Márquez, A.; Navarro-Fuster, V.; Francés, J.; Neipp, C.; Beléndez, A.; Pascual, I.

    2016-04-01

    Photopolymers are optical recording materials appealing for many different applications such as holography, data storage, interconnectors, solar concentrations, or wave-guides fabrication. Recently the capacity of photopolymers to record diffractive optical elements (DOE's) has been investigated. Different authors have reported proposes to record DOE like fork gratings, photonics structures, lenses, sinusoidal, blazed or fork gratings. In these experiments there are different experimental set-ups and different photopolymers. In this work due to the improvement in the spatial light modulation technology together with the photopolymer science we propose a recording experimental system of DOE using a Liquid Cristal based on Silicon (LCoS) display as a master to store complex DOE like cylindrical lenses. This technology permits us an accurate control of the phase and the amplitude of the recording beam, with a very small pixel size. The main advantage of this display is that permit us to modify the DOE automatically, we use the software of the LCoS to send the voltage to each pixel In this work we use a photopolymer composed by acrylamide (AA) as polymerizable monomer and polyvinyl alcohol (PVA). We use a coverplated and index matched photopolymer to avoid the influence of the thickness variation on the transmitted light. In order to reproduce the material behaviour during polymerization, we have designed our model to simulate cylindrical lenses and used Fresnel propagation to simulate the light propagation through the DOE and analyze the focal plane and the properties of the recorded lenses.

  5. Cylindrical boiloff calorimeters for testing of thermal insulation systems

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.; Johnson, W. L.; Meneghelli, B. J.; Coffman, B. E.

    2015-12-01

    Cryostats have been developed and standardized for laboratory testing of thermal insulation systems in a cylindrical configuration. Boiloff calorimetry is the measurement principle for determining the effective thermal conductivity (ke) and heat flux (q) of a test specimen at a fixed environmental condition (boundary temperatures, cold vacuum pressure, and residual gas composition). Through its heat of vaporization, liquid nitrogen serves as the energy meter, but the design is adaptable for various cryogens. The main instrument, Cryostat-100, is thermally guarded and directly measures absolute thermal performance. A cold mass assembly and all fluid and instrumentation feedthroughs are suspended from a lid of the vacuum canister; and a custom lifting mechanism allows the assembly and specimen to be manipulated easily. Each of three chambers is filled and vented through a single feedthrough for minimum overall heat leakage. The cold mass design precludes direct, solid-conduction heat transfer (other than through the vessel's outer wall itself) from one liquid volume to another, which is critical for achieving very low heat measurements. The cryostat system design details and test methods are discussed, as well as results for select thermal insulation materials. Additional cylindrical boiloff calorimeters and progress toward a liquid hydrogen apparatus are also discussed.

  6. Finite-amplitude dynamics of coupled cylindrical menisci.

    PubMed

    Cox, B L; Steen, P H

    2011-10-01

    The cylindrical meniscus is a liquid/gas interface of circular-cap cross-section constrained along its axis and bounded by end-planes. The inviscid motions of coupled cylindrical menisci are studied here. Motions result from the competition between inertia and surface tension forces. Restriction to shapes that are of circular-cap cross-section leads to an ordinary differential equation (ode) model, with the advantage that finite-amplitude stability can be examined. The second-order nonlinear ode model has a Hamiltonian structure, showing dynamical behavior like the Duffing-oscillator. The energy landscape has either a single- or double-welled potential depending on the extent of volume overfill. Total liquid volume is a bifurcation parameter, as in the corresponding problem for coupled spherical-cap droplets. Unlike the spherical-cap problem, however, axial disturbances can also destabilize, depending on overfill. For large volumes, previously known axial stability results are applied to find the limit at which axial symmetry is lost and comparison is made to the Plateau-Rayleigh limit. PMID:21723560

  7. Acoustic Microscope Inspection of Cylindrical Butt Laser Welds

    NASA Astrophysics Data System (ADS)

    Maev, R. Gr.; Severin, F.

    Presented work was made in order to develop the ultrasound technique for quality control of critical butt laser welds in automotive production. The set of powertrain assemblies was tested by high resolution acoustic microscopy method. The pulse-echo Tessonics AM 1102 scanning acoustic microscope was modified to accommodate cylindrical configuration of the parts. The spherically focused transducers with frequencies 15, 25 and 50 MHz were used; ultrasonic beam was focused on the joint area. Three-dimensional acoustic images were obtained and analyzed. The clear distinction between weld seam and remaining gap was demonstrated on the B- and C-scans representation. Seam depth varying from 0 up to 3.2 mm was measured along the weld. Different types of defects (porosity, cracks, lack of fusion) were detected and classified. The optimized analytical procedures for signal processing and advanced seam visualization were determined. The results were used as a basis for development of specialized instrumentation for inspection of this kind of parts in industrial environment. The technical requirements were established and the general design of new cylindrical acoustical scanner was made.

  8. An Experimental Investigation of the Implosion of Cylindrical Shell Structures

    NASA Astrophysics Data System (ADS)

    Ikeda, C. M.; Wilkerling, J.; Duncan, J. H.

    2009-11-01

    An experimental study of the physics of the implosion of cylindrical shell structures in a high-pressure water environment was performed. The shell structures are filled with air at atmospheric pressure and the implosions occur when the water pressure is raised above the shell buckling stability limit. High-speed photography (27,000 fps) was used to observe and measure the motion of the structure during its implosion. High-frequency underwater blast sensors recorded dynamic pressure waves at 13 positions in the tank. The cylindrical models are made from various aluminum alloys (diameter D = 39.1 mm, wall thickness t = 0.89 mm) and brass (D = 16.7 to 25.4 mm, t = 0.33 to 0.36 mm). The ends of the tubes were sealed with Aluminum caps. The pressure records are interpreted in light of the high-speed movies. Cylinder length-to-diameter (L/D) ratios between 6 and 10 were examined; in this range the cylinders implode in a mode 2 cross-sectional shape at pressures between 6.9 and 28.7 bar. It is found that the pressure versus time records from sensors placed at the same dimensionless radial position (r/D) from the cylinder surface scale well with time and pressure scales from cavitation bubble collapse theory.

  9. A cylindrical SPECT camera with de-centralized readout scheme

    NASA Astrophysics Data System (ADS)

    Habte, F.; Stenström, P.; Rillbert, A.; Bousselham, A.; Bohm, C.; Larsson, S. A.

    2001-09-01

    An optimized brain single photon emission computed tomograph (SPECT) camera is being designed at Stockholm University and Karolinska Hospital. The design goal is to achieve high sensitivity, high-count rate and high spatial resolution. The sensitivity is achieved by using a cylindrical crystal, which gives a closed geometry with large solid angles. A de-centralized readout scheme where only a local environment around the light excitation is readout supports high-count rates. The high resolution is achieved by using an optimized crystal configuration. A 12 mm crystal plus 12 mm light guide combination gave an intrinsic spatial resolution better than 3.5 mm (140 keV) in a prototype system. Simulations show that a modified configuration can improve this value. A cylindrical configuration with a rotating collimator significantly simplifies the mechanical design of the gantry. The data acquisition and control system uses early digitization and subsequent digital signal processing to extract timing and amplitude information, and monitors the position of the collimator. The readout system consists of 12 or more modules each based on programmable logic and a digital signal processor. The modules send data to a PC file server-reconstruction engine via a Firewire (IEEE-1394) network.

  10. Transurethral canine prostatectomy with a cylindrically diffusing fiber

    NASA Astrophysics Data System (ADS)

    Cromeens, Douglas M.; Johnson, Douglas E.; Price, Roger E.

    1994-09-01

    In this study, visual laser ablation of the prostate (VLAP) was performed on eight mongrel dogs utilizing a cylindrically diffusing fiber attached to a 1.06 neodymium:YAG (Nd:YAG) laser. All dogs received one continuous dose totaling 15,000 J (25 W for 10 min) applied from the vesical neck to the colliculus seminalis. There was no visible hemorrhage from the lasing intraoperatively in any dog. Postoperative recovery was uneventful with no dog experiencing urinary incontinence and only one incident of dysuria with urinary retention during their observation period. Gross and histopathologic examinations of serial sections of the prostate were performed from 2 hours to 7 weeks postoperatively and demonstrated a consistent spherical zone of destruction 2.9 cm (average) in diameter. We believe the simplified fiber placement and complete lack of postoperative complications in this small group of dogs suggest that the cylindrically diffusing fiber offers significant advantage over laterally deflecting fibers for transurethral prostatectomies in the dog.

  11. A torquing shearing interferometer for cylindrical wire array experiments

    SciTech Connect

    Pikuz, S. A.; Schrafel, P. C.; Shelkovenko, T. A.; Kusse, B. R.

    2008-10-15

    In standard shearing interferometry, a single probing beam passes through a perturbing medium and is then split into two beams. A linear shift results in an overlap, an interference, and a fringe pattern yielding the perturbing medium density profile. The probing beam usually needs to be larger than the perturbing medium so that part of it passes through a well separated low density region. During early time axial (end-on) views of imploding cylindrical wire arrays low density regions lie in between the high density regions that are near the initial wire positions. In addition, for end-on viewing, the probing beam diameter is limited by electrodes and is comparable to the array diameter. In this case a linear translation will not work but the overlap can be accomplished by an azimuthal rotation of one beam with respect to the other. Such a torquing shearing interferometer has been set up on the COBRA experiment to give time resolved, radial, and azimuthal electron density profiles during early time cylindrical wire array implosions.

  12. Microwave Plasma Excitation Using Cylindrical Cavity with Dual Injection

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yuichi; Nakamura, Keiji; Park, Soonam; Kobayashi, Satoru; Sugai, Hideo; Chubu University Team; Applied Materials Team; Nagoya Industrial Science Research Institute Team

    2015-09-01

    Large high-density plasmas have been generated by injecting magnetron-based microwaves radiated from slots cut on a wall of a rectangular or coaxial waveguide. However, a standing structural microwave in the waveguide often causes non-uniformity of plasma density. To minimize such inhomogeneity excited by the conventional waveguide, we adopt a resonant cylindrical cavity combined with a solid-state microwave amplifier. Microwave is injected into the cavity from two ports azimuthally apart by 90 degrees to each other (dual injection). FDTD simulations are performed for a TE111 mode resonant cavity excited by single or dual microwave injection. In the case of the dual injection with a phase difference of π/2, the wave field azimuthally rotates in the cavity, and hence the slots cut on a cavity bottom wall launch travelling waves, thus minimizing the azimuthal inhomogeneity of the resultant plasma. 40-cm-diameter plasmas are experimentally generated in argon at 0.1 ~ 5 Torr with microwaves of 2.4-2.5GHz and 400W. Threshold powers for plasma ignition are much less in dual injection than those in single injection. Optical emission images of the cylindrical plasmas show that the plasma uniformity is considerably improved in dual injection, particularly at high-pressure and low-power.

  13. Propagating Properties of Cylindrical Rayleigh Waves Generated by a Pulsed Laser Line Source

    NASA Astrophysics Data System (ADS)

    Hu, Wen-Xiang; Qian, Meng-Lu

    2004-07-01

    A two-dimensional theoretical model is used to analyse the acoustic field of cylindrical surface waves generated by a pulsed laser line source in the ablation regime. The complete dispersive curves for cylindrical Rayleigh wave are presented. The laser-generated transient acoustic field of cylindrical Rayleigh waves is calculated and the corresponding laser ultrasonic experiments are carried out. Both the numerical and experimental results are in good agreement.

  14. Why mercury prefers soft ligands

    SciTech Connect

    Riccardi, Demian M; Guo, Hao-Bo; Gu, Baohua; Parks, Jerry M; Summers, Anne; Miller, S; Liang, Liyuan; Smith, Jeremy C

    2013-01-01

    Mercury (Hg) is a major global pollutant arising from both natural and anthropogenic sources. Defining the factors that determine the relative affinities of different ligands for the mercuric ion, Hg2+, is critical to understanding its speciation, transformation, and bioaccumulation in the environment. Here, we use quantum chemistry to dissect the relative binding free energies for a series of inorganic anion complexes of Hg2+. Comparison of Hg2+ ligand interactions in the gaseous and aqueous phases shows that differences in interactions with a few, local water molecules led to a clear periodic trend within the chalcogenide and halide groups and resulted in the well-known experimentally observed preference of Hg2+ for soft ligands such as thiols. Our approach establishes a basis for understanding Hg speciation in the biosphere.

  15. Unique features of cylindrical type solar-module contrasted with plane or conventional type ones

    NASA Astrophysics Data System (ADS)

    Hiraki, Hirohisa; Hiraki, Akio; Maeda, Masakatsu; Takahashi, Yasuo

    2012-08-01

    Due to their shape and construction, Cu(In,Ga)Se2 [CIGS] cylindrical photovoltaic [PV] panels have unique features that planar or conventional PV panels do not have. For example, a) they capture sunlight over an angular range of 360°, b) they are self-ballasting (no roof penetrations, no attachments required) and c) they are high-reliability hermetically sealed cylindrical packages. In field tests in Japan, cylindrical PV panels have proven their durability against typhoons, and also their excellent electrical properties. Finally, as a new application of cylindrical PV panels, we suggest the new concept of fusion or combination of PV generation and agriculture.

  16. Discrete-ordinates solution of radiative transfer equation in nonaxisymmetric cylindrical enclosures

    SciTech Connect

    Jamaluddin, A.S.; Smith, P.J. Utah, University, Salt Lake City )

    1992-06-01

    The S4 discrete-ordinates approximation is used to solve the radiative transfer equation in nonasymmetric (i.e., three-dimensional) cylindrical enclosures containing absorbing-emitting and scattering media, with and without the temperature profile known a priori. Because neither detailed experimental data nor predictions from a zone or Monte-Carlo model for three-dimensional cylindrical enclosures are available, cylindrical equivalents of three-dimensional rectangular enclosures, for which zone model predictions of radiative transfer are available, are used in model evaluation. Limited evaluation of the model shows that the discrete-ordinates method provides acceptable predictions of radiative transfer in nonaxisymmetric cylindrical enclosures. 12 refs.

  17. Evidence for Differential Assortative Female Preference in Association with Refugial Isolation of Rainbow Skinks in Australia's Tropical Rainforests

    PubMed Central

    Dolman, Gaynor

    2008-01-01

    Background Divergence driven by female preference can give rise to pre-mating isolation more rapidly than post-mating isolation can evolve through the accumulation of allelic incompatibilities. Moreover pre-mating isolation may be more effective at maintaining morphological differentiation between divergent populations. In the context of Australian rainforest endemic skinks that were historically subjected to refugial isolation, this study examined the following predictions: 1) that assortative female preference is associated with more recent divergence of southern C. rubrigularis (S-RED) and C. rhomboidalis (BLUE), but not with deeply divergent S-RED and northern C. rubrigularis (N-RED); and 2) that upon secondary contact, morphological differentiation is maintained between S-RED and BLUE, whereas N-RED and S-RED remain morphogically indistinguishable. Principal Findings Female preference trials found no evidence for assortative female preference between N-RED and S-RED, supporting a previous genetic hybrid zone study which inferred post-mating but no pre-mating isolation. In contrast there is evidence for assortative female preference between S-RED and BLUE, with BLUE females preferring to associate with BLUE males, but S-RED females showing no preference. Multi-locus coalescent analyses, used to estimate post-divergence gene-flow between proximally located S-RED and BLUE populations, rejected zero gene-flow from BLUE to S-RED and thus RED and BLUE have maintained morphological differentiation despite secondary contact. Morphometric analyses confirmed a lack of morphological divergence between N-RED and S-RED and established that BLUE is morphologically divergent from RED in traits other than throat colour. Conclusions/Significance Long-term isolation has been sufficient to generate post-mating isolation but no morphological divergence between N-RED and S-RED. In contrast, greater morphological differentiation is associated with evidence for assortative female

  18. Directed self-assembly of diblock copolymers in cylindrical confinement: effect of underfilling and air-polymer interactions on configurations

    NASA Astrophysics Data System (ADS)

    Carpenter, Corinne L.; Delaney, Kris T.; Laachi, Nabil; Fredrickson, Glenn H.

    2015-03-01

    Directed self-assembly (DSA) of block copolymers has attracted attention for its use as a simple, cost- effective patterning tool for creating vertical interconnect access (VIA) channels in nanoelectronic devices.1, 2 This technique supplements existing lithographic technologies to allow for the creation of high-resolution cylindrical holes whose diameter and placement can be precisely controlled. In this study, we use self-consistent field theory (SCFT) simulations to investigate the equilibrium configurations of under-filled DSA systems with air-polymer interactions. We report on a series of SCFT simulations of our three species (PMMA-b-PS diblock and air) model in cylindrical confinement to explore the role of template diameter, under-fill fraction (i.e. volume fraction of air), air-polymer surface interaction and polymer-side wall/substrate interactions on equilibrium morphologies in an under-filled template with a free top surface. We identify parameters and system configurations where a meniscus appears and explore cases with PMMA-attractive, PS-attractive, and all-neutral walls to understand the effects of wall properties on meniscus geometry and DSA morphology. An important outcome is an understanding of the parameters that control the contact angle of the meniscus with the wall, as it is one of the simplest quantitative measures of the meniscus shape. Ultimately, we seek to identify DSA formulations, templates, and surface treatments with predictable central cylinder diameter and a shallow contact angle, as these factors would facilitate broad process windows and ease of manufacturing.

  19. Morphological neural networks

    SciTech Connect

    Ritter, G.X.; Sussner, P.

    1996-12-31

    The theory of artificial neural networks has been successfully applied to a wide variety of pattern recognition problems. In this theory, the first step in computing the next state of a neuron or in performing the next layer neural network computation involves the linear operation of multiplying neural values by their synaptic strengths and adding the results. Thresholding usually follows the linear operation in order to provide for nonlinearity of the network. In this paper we introduce a novel class of neural networks, called morphological neural networks, in which the operations of multiplication and addition are replaced by addition and maximum (or minimum), respectively. By taking the maximum (or minimum) of sums instead of the sum of products, morphological network computation is nonlinear before thresholding. As a consequence, the properties of morphological neural networks are drastically different than those of traditional neural network models. In this paper we consider some of these differences and provide some particular examples of morphological neural network.

  20. Filament identification through mathematical morphology

    NASA Astrophysics Data System (ADS)

    Koch, Eric W.; Rosolowsky, Erik W.

    2015-10-01

    We present a new algorithm for detecting filamentary structure FILFINDER. The algorithm uses the techniques of mathematical morphology for filament identification, presenting a complementary approach to current algorithms which use matched filtering or critical manifolds. Unlike other methods, FILFINDER identifies filaments over a wide dynamic range in brightness. We apply the new algorithm to far-infrared imaging data of dust emission released by the Herschel Gould Belt Survey team. Our preliminary analysis characterizes both filaments and fainter striations. We find a typical filament width of 0.09 pc across the sample, but the brightness varies from cloud to cloud. Several regions show a bimodal filament brightness distribution, with the bright mode (filaments) being an order of magnitude brighter than the faint mode (striations). Using the Rolling Hough Transform, we characterize the orientations of the striations in the data, finding preferred directions that agree with magnetic field direction where data are available. There is a suggestive but noisy correlation between typical filament brightness and literature values of the star formation rates for clouds in the Gould Belt.

  1. Absolute magnetic helicity and the cylindrical magnetic field

    NASA Astrophysics Data System (ADS)

    Low, B. C.

    2011-05-01

    The different magnetic helicities conserved under conditions of perfect electrical conductivity are expressions of the fundamental property that every evolving fluid surface conserves its net magnetic flux. This basic hydromagnetic point unifies the well known Eulerian helicities with the Lagrangian helicity defined by the conserved fluxes frozen into a prescribed set of disjoint toroidal tubes of fluid flowing as a permanent partition of the entire fluid [B. C. Low, Astrophys. J. 649, 1064 (2006)]. This unifying theory is constructed from first principles, beginning with an analysis of the Eulerian and Lagrangian descriptions of fluids, separating the ideas of fluid and magnetic-flux tubes and removing the complication of the magnetic vector potential's free gauge from the concept of helicity. The analysis prepares for the construction of a conserved Eulerian helicity, without that gauge complication, to describe a 3D anchored flux in an upright cylindrical domain, this helicity called absolute to distinguish it from the well known relative helicity. In a version of the Chandrasekhar-Kendall representation, the evolving field at any instant is a unique superposition of a writhed, untwisted axial flux with a circulating flux of field lines all closed and unlinked within the cylindrical domain. The absolute helicity is then a flux-weighted sum of the writhe of that axial flux and its mutual linkage with the circulating flux. The absolute helicity is also conserved if the frozen-in field and its domain are continuously deformed by changing the separation between the rigid cylinder-ends with no change of cylinder radius. This hitherto intractable cylindrical construction closes a crucial conceptual gap for the fundamentals to be complete at last. The concluding discussion shows the impact of this development on our understanding of helicity, covering (i) the helicities of wholly contained and anchored fields; (ii) the Eulerian and Lagrangian descriptions of field

  2. Octopamine influences honey bee foraging preference.

    PubMed

    Giray, Tugrul; Galindo-Cardona, Alberto; Oskay, Devrim

    2007-07-01

    Colony condition and differences in individual preferences influence forage type collected by bees. Physiological bases for the changing preferences of individual foragers are just beginning to be examined. Recently, for honey bees octopamine is shown to influence age at onset of foraging and probability of dance for rewards. However, octopamine has not been causally linked with foraging preference in the field. We tested the hypothesis that changes in octopamine may alter forage type (preference hypothesis). We treated identified foragers orally with octopamine or its immediate precursor, tyramine, or sucrose syrup (control). Octopamine-treated foragers switched type of material collected; control bees did not. Tyramine group results were not different from the control group. In addition, sugar concentrations of nectar collected by foragers after octopamine treatment were lower than before treatment, indicating change in preference. In contrast, before and after nectar concentrations for bees in the control group were similar. These results, taken together, support the preference hypothesis. PMID:17574568

  3. Octopamine influences honey bee foraging preference

    PubMed Central

    Giray, Tugrul; Galindo, Alberto; Oskay, Devrim

    2010-01-01

    Colony condition and differences in individual preferences influence forage type collected by bees. Physiological bases for the changing preferences of individual foragers are just beginning to be examined. Recently, for honey bees octopamine is shown to influence age at onset of foraging and probability of dance for rewards. However, octopamine has not been causally linked with foraging preference in the field. We tested the hypothesis that changes in octopamine may alter forage type (preference hypothesis). We treated identified foragers orally with octopamine or its immediate precursor, tyramine, or sucrose syrup (control). Octopamine treated foragers switched type of material collected, control bees did not. Tyramine group results were not different from the control group. In addition, sugar concentrations of nectar collected by foragers after octopamine treatment were lower than before treatment, indicating change in preference. In contrast, before and after nectar concentrations for bees in the control group were similar. These results, taken together, support the preference hypothesis. PMID:17574568

  4. Strategies for Global Optimization of Temporal Preferences

    NASA Technical Reports Server (NTRS)

    Morris, Paul; Morris, Robert; Khatib, Lina; Ramakrishnan, Sailesh

    2004-01-01

    A temporal reasoning problem can often be naturally characterized as a collection of constraints with associated local preferences for times that make up the admissible values for those constraints. Globally preferred solutions to such problems emerge as a result of well-defined operations that compose and order temporal assignments. The overall objective of this work is a characterization of different notions of global preference, and to identify tractable sub-classes of temporal reasoning problems incorporating these notions. This paper extends previous results by refining the class of useful notions of global temporal preference that are associated with problems that admit of tractable solution techniques. This paper also answers the hitherto open question of whether problems that seek solutions that are globally preferred from a Utilitarian criterion for global preference can be found tractably.

  5. MHC-assortative facial preferences in humans

    PubMed Central

    Roberts, S. Craig; Little, Anthony C; Gosling, L. Morris; Jones, Benedict C; Perrett, David I; Carter, Vaughan; Petrie, Marion

    2005-01-01

    Individuals tend to choose mates who are sufficiently genetically dissimilar to avoid inbreeding. As facial attractiveness is a key factor in human mate preference, we investigated whether facial preferences were related to genetic dissimilarity. We asked female volunteers to rate the attractiveness of men from photographs and compared these results with individual genotypes at the major histocompatibility complex (MHC). In contrast to previously reported preferences based on odour, we found a non-significant tendency for women to rate MHC-similar faces as more attractive, suggesting a preference for cues to a self-similar MHC in faces. Further analysis revealed that male faces received higher attractiveness scores when rated by women who were MHC-similar than by MHC-dissimilar women. Although unexpected, this MHC-similar facial preference is consistent with other studies documenting assortative preferences in humans, including for facial phenotype. PMID:17148217

  6. Candidate preferences and expectations of election outcomes

    PubMed Central

    Delavande, Adeline; Manski, Charles F.

    2012-01-01

    Analysis of data from the American Life Panel shows that in the presidential election of 2008 and in multiple statewide elections in 2010, citizens exhibited large differences in their expectations of election outcomes. Expectations were strongly positively associated with candidate preferences, persons tending to believe that their preferred candidate is more likely to win the election. Committed supporters of opposing candidates regularly differed by 20–30% in their assessments of the likelihood that each candidate would win. These findings contribute evidence on the false consensus effect, the empirical regularity that own preferences tend to be positively associated with perceptions of social preferences. We used unique measures of preferences and perceptions that enabled respondents to express uncertainty flexibly. We studied a setting that would a priori seem inhospitable to false consensus—one where persons have little private information on social preferences but substantial common knowledge provided by media reports of election polls. PMID:22355121

  7. Fin-mutant female zebrafish (Danio rerio) exhibit differences in association preferences for male fin length

    PubMed Central

    Gumm, Jennifer M.; Snekser, Jennifer L.; Iovine, M. Kathryn

    2009-01-01

    Females often choose to associate with males that have exaggerated traits. In fishes, this may reflect an overall preference for larger size in a potential mate. Female zebrafish (Danio rerio) prefer males with larger bodies but not longer fins. The availability of mutant and transgenic strains of zebrafish make this a unique model system in which to study the role of phenotypic variation in social and sexual behavior. We used mutant strains of zebrafish with truncated (short fin) and exaggerated (long fin) fins to further examine female preferences for fin length in dichotomous association tests. Wild type females showed no preferences between wild type males and short fin mutant males or between wild type males and long fin mutant males. short fin females also showed no preference for short fin males or wild type males while long fin females preferred to associate with long fin males over wild type males. These results suggest that the single gene long fin mutation that results in altered fin morphological may also be involved in a related female association preference. PMID:18848866

  8. Do plant mites commonly prefer the underside of leaves?

    PubMed

    Sudo, Masaaki; Osakabe, Masahiro

    2011-09-01

    The adaxial (upper) and abaxial (lower) surfaces of a plant leaf provide heterogeneous habitats for small arthropods with different environmental conditions, such as light, humidity, and surface morphology. As for plant mites, some agricultural pest species and their natural enemies have been observed to favor the abaxial leaf surface, which is considered an adaptation to avoid rain or solar ultraviolet radiation. However, whether such a preference for the leaf underside is a common behavioral trait in mites on wild vegetation remains unknown. The authors conducted a 2-year survey on the foliar mite assemblage found on Viburnum erosum var. punctatum, a deciduous shrub on which several mite taxa occur throughout the seasons, and 14 sympatric tree or shrub species in secondary broadleaf-forest sites in Kyoto, west-central Japan. We compared adaxial-abaxial surface distributions of mites among mite taxa, seasons, and morphology of host leaves (presence/absence of hairs and domatia). On V. erosum var. punctatum, seven of 11 distinguished mite taxa were significantly distributed in favor of abaxial leaf surfaces and the trend was seasonally stable, except for Eriophyoidea. Mite assemblages on 15 plant species were significantly biased towards the abaxial leaf surfaces, regardless of surface morphology. Our data suggest that many mite taxa commonly prefer to stay on abaxial leaf surfaces in wild vegetation. Oribatida displayed a relatively neutral distribution, and in Tenuipalpidae, the ratio of eggs collected from the adaxial versus the abaxial side was significantly higher than the ratio of the motile individuals, implying that some mite taxa exploit adaxial leaf surfaces as habitat. PMID:21472503

  9. Working with clients by incorporating their preferences.

    PubMed

    Tompkins, Kelley A; Swift, Joshua K; Callahan, Jennifer L

    2013-09-01

    Working with clients by integrating their therapy preferences into the treatment decision-making process has been identified as an important part of evidence-based practice in psychology. Accommodating client preferences has also been demonstrated to lead to fewer treatment dropouts and improved therapy outcomes. In this article, we present a number of clinical interventions or techniques for addressing client preferences in psychotherapy. Clinical examples demonstrating the techniques are also provided. PMID:24000835

  10. Technical Note: Algebraic iterative image reconstruction using a cylindrical image grid for tetrahedron beam computed tomography

    PubMed Central

    Kim, Joshua; Ionascu, Dan; Zhang, Tiezhi

    2013-01-01

    Purpose: To accelerate iterative algebraic reconstruction algorithms using a cylindrical image grid. Methods: Tetrahedron beam computed tomography (TBCT) is designed to overcome the scatter and detector problems of cone beam computed tomography (CBCT). Iterative algebraic reconstruction algorithms have been shown to mitigate approximate reconstruction artifacts that appear at large cone angles, but clinical implementation is limited by their high computational cost. In this study, a cylindrical voxelization method on a cylindrical grid is developed in order to take advantage of the symmetries of the cylindrical geometry. The cylindrical geometry is a natural fit for the circular scanning trajectory employed in volumetric CT methods such as CBCT and TBCT. This method was implemented in combination with the simultaneous algebraic reconstruction technique (SART). Both two- and three-dimensional numerical phantoms as well as a patient CT image were utilized to generate the projection sets used for reconstruction. The reconstructed images were compared to the original phantoms using a set of three figures of merit (FOM). Results: The cylindrical voxelization on a cylindrical reconstruction grid was successfully implemented in combination with the SART reconstruction algorithm. The FOM results showed that the cylindrical reconstructions were able to maintain the accuracy of the Cartesian reconstructions. In three dimensions, the cylindrical method provided better accuracy than the Cartesian methods. At the same time, the cylindrical method was able to provide a speedup factor of approximately 40 while also reducing the system matrix storage size by 2 orders of magnitude. Conclusions: TBCT image reconstruction using a cylindrical image grid was able to provide a significant improvement in the reconstruction time and a more compact system matrix for storage on the hard drive and in memory while maintaining the image quality provided by the Cartesian voxelization on a

  11. Analog model for thermoviscous propagation in a cylindrical tube.

    PubMed

    Thompson, Stephen C; Gabrielson, Thomas B; Warren, Daniel M

    2014-02-01

    Modeling acoustic propagation in tubes including the effects of thermoviscous losses at the tube walls is important in applications such as thermoacoustics, hearing aids, and wind musical instruments. Frequency dependent impedances for a tube transmission line model in terms of the so-called thermal and viscous functions are well established, and form the basis for frequency domain analysis of systems that include tubes. However, frequency domain models cannot be used for systems in which significant nonlinearities are important, as is the case with the pressure-flow relationship through the reed in a woodwind instrument. This paper describes a cylindrical tube model based on a continued fraction expansion of the thermal and viscous functions. The model can be represented as an analog circuit model which allows its use in time domain system modeling. This model avoids problems with fractional derivatives in the time domain. PMID:25234868

  12. Global modes of flute instability of a rotating cylindrical plasma

    SciTech Connect

    Sorokina, E. A.

    2009-05-15

    The influence of rotation on the flute instability of a cylindrical gravitating plasma in a straight inhomogeneous magnetic field is studied in the framework of one-fluid magnetohydrodynamics. The dispersion relation and integral expression for the instability growth rate of eigenmodes are derived. It is shown that, in the framework of the given problem, rotation is a destabilizing factor, and the corresponding theorem is proved for the general case. For a linear radial profile of the rotation frequency, the structure of eigenmodes is calculated. The growth rate of these modes is shown to increase with increasing rotation velocity and azimuthal mode number. It is found that plasma rotation in the eigenmode localization region leads to the displacement of perturbation from the rotation region, which results in a decrease in the instability growth rate. The absence of eigenmodes (i.e., exponential instability of the system) for certain profiles of the density and rotation frequency is demonstrated.

  13. Ductile fracture of cylindrical vessels containing a large flaw

    NASA Technical Reports Server (NTRS)

    Erdogan, F.; Irwin, G. R.; Ratwani, M.

    1976-01-01

    The fracture process in pressurized cylindrical vessels containing a relatively large flaw is considered. The flaw is assumed to be a part-through or through meridional crack. The flaw geometry, the yield behavior of the material, and the internal pressure are assumed to be such that in the neighborhood of the flaw the cylinder wall undergoes large-scale plastic deformations. Thus, the problem falls outside the range of applicability of conventional brittle fracture theories. To study the problem, plasticity considerations are introduced into the shell theory through the assumptions of fully-yielded net ligaments using a plastic strip model. Then a ductile fracture criterion is developed which is based on the concept of net ligament plastic instability. A limited verification is attempted by comparing the theoretical predictions with some existing experimental results.

  14. Nonlinear effects for a cylindrical gravitational two-soliton

    NASA Astrophysics Data System (ADS)

    Tomizawa, Shinya; Mishima, Takashi

    2015-06-01

    Using a cylindrical soliton solution to the four-dimensional vacuum Einstein equation, we study the nonlinear effects of gravitational waves, such as Faraday rotation and the time-shift phenomenon. In a previous work, we analyzed the single-soliton solution constructed using Pomeransky's improved inverse scattering method. In this work, we construct a new two-soliton solution with complex-conjugate poles, by which we can avoid the light-cone singularities that are unavoidable in a single-soliton case. In particular, we compute the amplitudes of nonlinear gravitational waves and the time dependence of the polarizations. Furthermore, we consider the time-shift phenomenon for soliton waves, which means that a wave packet can propagate at a velocity slower than light.

  15. Performance of a Low-Power Cylindrical Hall Thruster

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Markusic, Thomas E.; Stanojev, Boris J.; Dehoyos, Amado; Raitses, Yevgeny; Smirnov, Artem; Fisch, Nathaniel J.

    2007-01-01

    Recent mission studies have shown that a Hall thruster which operates at relatively constant thrust efficiency (45-55%) over a broad power range (300W - 3kW) is enabling for deep space science missions when compared with slate-of-the-art ion thrusters. While conventional (annular) Hall thrusters can operate at high thrust efficiency at kW power levels, it is difficult to construct one that operates over a broad power envelope down to 0 (100 W) while maintaining relatively high efficiency. In this note we report the measured performance (I(sub sp), thrust and efficiency) of a cylindrical Hall thruster operating at 0 (100 W) input power.

  16. Planar and cylindrical active microwave temperature imaging: numerical simulations.

    PubMed

    Rius, J M; Pichot, C; Jofre, L; Bolomey, J C; Joachimowicz, N; Broquetas, A; Ferrando, M

    1992-01-01

    A comparative study at 2.45 GHz concerning both measurement and reconstruction parameters for planar and cylindrical configurations is presented. For the sake of comparison, a numerical model consisting of two nonconcentric cylinders is considered and reconstructed using both geometries from simulated experimental data. The scattered fields and reconstructed images permit extraction of very useful information about dynamic range, sensitivity, resolution, and quantitative image accuracy for the choice of the configuration in a particular application. Both geometries can measure forward and backward scattered fields. The backscattering measurement improves the image resolution and reconstruction in lossy mediums, but, on the other hand, has several dynamic range difficulties. This tradeoff between forward only and forward-backward field measurement is analyzed. As differential temperature imaging is a weakly scattering problem, Born approximation algorithms can be used. The simplicity of Born reconstruction algorithms and the use of FFT make them very attractive for real-time biomedical imaging systems. PMID:18222887

  17. Venus - Simple Cylindrical Map of Surface (Eastern Half)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The eastern half of the planet is displayed in this simple cylindrical map of the surface of Venus. The left edge of the image is at 52.5 degrees east longitude, the right edge at 240 degrees east longitude. The top and bottom of the image are at 90 degrees north latitude and 90 degrees south latitude, respectively. Magellan synthetic aperture radar mosaics from the first cycle of Magellan mapping are mapped onto a rectangular latitude-longitude grid to create this image. Data gaps are filled with Pioneer Venus Orbiter altimetric data, or a constant mid-range value. Simulated color is used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced by the Solar System Visualization project and the Magellan science team at the JPL Multimission Image Processing Laboratory.

  18. Venus - Simple Cylindrical Map of Surface (Western Half)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The western half of Venus is displayed in this simple cylindrical map of the planet's surface. The left edge of the image is at 240 degrees east longitude, the right edge at 67.5 degrees east longitude. The top and bottom of the image are at 90 degrees north latitude and 90 degrees south latitude, respectively. Magellan synthetic aperture radar mosaics from the first cycle of Magellan mapping are mapped onto a rectangular latitude-longitude grid to create this image. Data gaps are filled with Pioneer-Venus Orbiter altimetric data, or a constant mid-range value. Simulated color is used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced by the Solar System Visualization project and the Magellan science team at the JPL Multimission Image Processing Laboratory.

  19. An experimental study of oscillatory thermocapillary convection in cylindrical containers

    NASA Technical Reports Server (NTRS)

    Kamotani, Y.; Lee, J. H.; Ostrach, S.; Pline, A.

    1992-01-01

    An experimental study of oscillatory thermocapillary in small cylindrical containers with a heating wire placed along the center axis is performed by investigating the flow structures and temperature distributions under various conditions. To supplement the flow visualization the surface is scanned using an infrared imager. Here, 2 cS viscosity (Pr = 27) silicone oil is used as the test fluid. It is observed that beyond a certain temperature difference between the container wall and the heating wire, a distinctive unsteady flow pattern appears. This unsteady phenomenon is identified as oscillatory thermocapillary. After the onset of oscillations the flow structure becomes nonaxisymmetric and wave motion is observed at the free surface. It is shown that the critical temperature difference is independent of container dimensions if the aspect ratio is fixed.

  20. Large Deformation Behavior of Long Shallow Cylindrical Composite Panels

    NASA Technical Reports Server (NTRS)

    Carper, Douglas M.; Hyer, Michael W.; Johnson, Eric R.

    1991-01-01

    An exact solution is presented for the large deformation response of a simply supported orthotropic cylindrical panel subjected to a uniform line load along a cylinder generator. The cross section of the cylinder is circular and deformations up to the fully snapped through position are investigated. The orthotropic axes are parallel to the generator and circumferential directions. The governing equations are derived using laminated plate theory, nonlinear strain-displacement relations, and applying variational principles. The response is investigated for the case of a panel loaded exactly at midspan and for a panel with the load offset from midspan. The mathematical formulation is one dimensional in the circumferential coordinate. Solutions are obtained in closed-form. An experimental apparatus was designed to load the panels. Experimental results of displacement controlled tests performed on graphite-epoxy curved panels are compared with analytical predictions.

  1. Response of long shallow cylindrical panels to radial line loads

    NASA Technical Reports Server (NTRS)

    Johnson, E. R.; Hyer, M. W.; Carper, D. M.

    1984-01-01

    The large displacement static response of shallow orthotropic panels subjected to lateral loading is examined both theoretically and experimentally. The panels are circular cylindrical open shells which are also thin and long. The straight edges are simply supported at a fixed distance apart, and the curved edges are free. The lateral load is a spatially uniform line load acting along the generator direction of the cylinder, and is directed radially inward toward the center of curvature. The load induces a circumferential thrust, and the panel can, and does, snap-through to an inverted configuration at the buckling load. The effect of load position on the response is also examined. The test panels discussed in the paper are /(90/0)3/S graphite-epoxy laminates. Nominal dimensions are a radius of 60 in., a thickness of 0.060 in., and an arc length of 12 in. Very good agreement between theory and experiment is achieved.

  2. Transverse shear effect in a circumferentially cracked cylindrical shell

    NASA Technical Reports Server (NTRS)

    Delale, F.; Erdogan, F.

    1979-01-01

    The objectives of the paper are to solve the problem of a circumferentially-cracked cylindrical shell by taking into account the effect of transverse shear, and to obtain the stress intensity factors for the bending moment as well as the membrane force as the external load. The formulation of the problem is given for a specially orthotropic material within the framework of a linearized shallow shell theory. The particular theory used permits the consideration of all five boundary conditions as to moment and stress resultants on the crack surface. The effect of Poisson's ratio on the stress intensity factors and the nature of the out-of-plane displacement along the edges of the crack, i.e., bulging, are also studied.

  3. Vibrations of cantilevered shallow cylindrical shells of rectangular planform

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-01-01

    A cantilevered, shallow shell of circular cylindrical curvature and rectangular planform exhibits free vibration behavior which differs considerably from that of a cantilevered beam or of a flat plate. Some numerical results can be found for the problem in the previously published literature, mainly obtained by using various finite element methods. The present paper is the first definitive study of the problem, presenting accurate non-dimensional frequency parameters for wide ranges of aspect ratio, shallowness ratio and thickness ratio. The analysis is based upon shallow shell theory. Numerical results are obtained by using the Ritz method, with algebraic polynomial trial functions for the displacements. Convergence is investigated, with attention being given both to the number of terms taken for each co-ordinate direction and for each of the three components of displacement. Accuracy of the results is also established by comparison with finite element results for shallow shells and with other accurate flat plate solutions.

  4. Nonlinear saturation amplitude of cylindrical Rayleigh—Taylor instability

    NASA Astrophysics Data System (ADS)

    Liu, Wan-Hai; Yu, Chang-Ping; Ye, Wen-Hua; Wang, Li-Feng

    2014-09-01

    The nonlinear saturation amplitude (NSA) of the fundamental mode in the classical Rayleigh—Taylor instability with a cylindrical geometry for an arbitrary Atwood number is analytically investigated by considering the nonlinear corrections up to the third order. The analytic results indicate that the effects of the initial radius of the interface (r0) and the Atwood number (A) play an important role in the NSA of the fundamental mode. The NSA of the fundamental mode first increases gently and then decreases quickly with increasing A. For a given A, the smaller the r0/λ (λ is the perturbation wavelength), the larger the NSA of the fundamental mode. When r0/λ is large enough (r0 ≫ λ), the NSA of the fundamental mode is reduced to the prediction in the previous literatures within the framework of the third-order perturbation theory.

  5. Shear stabilization of the capillary breakup of a cylindrical interface

    NASA Technical Reports Server (NTRS)

    Russo, Mathew J.; Steen, Paul H.

    1989-01-01

    A cylindrical interface containing a viscous liquid set into axial motion is subject to a capillary and to a surface-wave instability. Clues from previous studies suggest that, even though both mechanisms separately are destabilizing, under certain circumstances their mutual interaction can lead to a stable interface; shear can stabilize capillary breakup. Here, an axial flow through an annular cross section bounded on the inside by a rigid rod and on the outside by a deformable interface is considered. The competition between the two mechanisms is studied through the temporal growth of infinitesimal axisymmetric and nonaxisymmetric disturbances. This examination of temporal stability shows that, indeed, for geometries corresponding to thin annular layers both instabilities can be completely suppressed (disturbances of all wavelengths decay).

  6. First and Second Sound in Cylindrically Trapped Gases

    SciTech Connect

    Bertaina, G.; Stringari, S.; Pitaevskii, L.

    2010-10-08

    We investigate the propagation of density and temperature waves in a cylindrically trapped gas with radial harmonic confinement. Starting from two-fluid hydrodynamic theory we derive effective 1D equations for the chemical potential and the temperature which explicitly account for the effects of viscosity and thermal conductivity. Differently from quantum fluids confined by rigid walls, the harmonic confinement allows for the propagation of both first and second sound in the long wavelength limit. We provide quantitative predictions for the two sound velocities of a superfluid Fermi gas at unitarity. For shorter wavelengths we discover a new surprising class of excitations continuously spread over a finite interval of frequencies. This results in a nondissipative damping in the response function which is analytically calculated in the limiting case of a classical ideal gas.

  7. Rigid-drift magnetohydrodynamic equilibria for cylindrical screw pinches

    NASA Technical Reports Server (NTRS)

    Turner, L.

    1979-01-01

    The rigid-drift equations of MHD equilibria in cylindrical geometry are solved analytically in terms of an infinite series of hypergeometric functions for the case where the pressure is proportional to the square of number density and the current density is arbitrarily pitched. Solutions are obtained for a pure Z pinch, a pure theta pinch, and a general screw pinch. It is found that the shapes of the pressure and magnetic-field profiles are completely determined by the model once two parameters are specified: the local plasma beta on the axis and a quantity related to the pitch of the current density. A set of profiles that resemble those observed experimentally in reversed-field pinches is presented. The results also indicate that hollow pressure profiles and reversed Bz profiles can occur either simultaneously or independently and that the pressure always falls to zero at a finite value of the radius.

  8. Reversed Field Pinch Dynamics in Toroidal and Cylindrical Geometries

    NASA Astrophysics Data System (ADS)

    Morales, Jorge A.; Bos, Wouter J. T.; Schneider, Kai; Montgomery, David C.

    2014-10-01

    The effect of the curvature of the imposed magnetic field on Reversed Field Pinch dynamics is investigated by comparing the flow of a magnetofluid in a torus with aspect ratio 1.83, with the flow in a periodic cylinder. It is found that an axisymmetric toroidal mode is always present in the toroidal, but absent in the cylindrical configuration. In particular, in contrast to the cylinder, the toroidal case presents a double poloidal recirculation cell with a shear localized at the plasma edge. Quasi-single-helicity states are found to be more persistent in toroidal than in periodic cylinder geometry. This work was supported by the contract SiCoMHD (ANR-Blanc 2011-045), computing time was supplied by IDRIS, project 22206.

  9. Fiber grating systems used to measure strain in cylindrical structures

    NASA Astrophysics Data System (ADS)

    Udd, Eric; Corona-Bittick, Kelli; Slattery, Kerry T.; Dorr, Donald J.; Crowe, C. Robert; Vandiver, Terry L.; Evans, Robert N.

    1997-07-01

    Fiber optic grating systems are described that have been used to measure strain in cylindrical structures. The applications of these systems to a composite utility pole and to a composite missile body are described. Composite utility poles have significant advantages with respect to wooden utility poles that include superior strength and uniformity; light weight for ease of deployment; the ability to be recycled, reducing hazardous waste associated with chemically treated wooden poles; and compatibility with embedded fiber optic sensors, allowing structural loads to be monitored. Tests conducted of fiber optic grating sensors in combination with an overcoupled coupler demodulation system to support structural testing of a 22-ft composite pole are reported. Monitoring strain in composite missile bodies has the potential to improve the quality of manufactured parts, support performance testing, and enhance safety during long periods of storage. Strain measurements made with fiber optic grating and electrical strain gauges are described.

  10. A cylindrical shell with an arbitrarily oriented crack

    NASA Technical Reports Server (NTRS)

    Yahsi, O. S.; Erdogan, F.

    1982-01-01

    The general problem of a shallow shell with constant curvatures is considered. It is assumed that the shell contains an arbitrarily oriented through crack and the material is specially orthotropic. The nonsymmetric problem is solved for arbitrary self equilibrating crack surface tractions, which, added to an appropriate solution for an uncracked shell, would give the result for a cracked shell under most general loading conditions. The problem is reduced to a system of five singular integral equations in a set of unknown functions representing relative displacements and rotations on the crack surfaces. The stress state around the crack tip is asymptotically analyzed and it is shown that the results are identical to those obtained from the two dimensional in plane and antiplane elasticity solutions. The numerical results are given for a cylindrical shell containing an arbitrarily oriented through crack. Some sample results showing the effect of the Poisson's ratio and the material orthotropy are also presented.

  11. Ingested cylindrical batteries in an incarcerated male: a caustic tale!

    PubMed

    Dunphy, Louise; Maatouk, Mohamed; Raja, Mazhar; O'Hara, Richard

    2015-01-01

    A 37-year-old incarcerated man presented to the accident and emergency department following the deliberate ingestion of eight cylindrical batteries. He also admitted to inserting a razor blade wrapped in cling-film into his rectum; in addition, he sustained a self-inflicted laceration to his left antecubital fossa, using the metal casing from a battery. His medical history included a borderline and emotionally unstable personality disorder. He had ingested several batteries 12 months previously and required an emergency laparotomy to retrieve them. On the present admission, as there was no clinical evidence of small bowel obstruction, he was treated conservatively with serial radiographs. Following conservative management, the batteries failed to progress through the gastrointestinal tract, hence a laparotomy was performed and all the batteries were extricated. This paper discusses the management and associated sequelae of patients presenting following the intentional ingestion of a battery. PMID:26420691

  12. Vibrations of cantilevered shallow cylindrical shells of rectangular planform

    NASA Astrophysics Data System (ADS)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-10-01

    A cantilevered, shallow shell of circular cylindrical curvature and rectangular planform exhibits free vibration behavior which differs considerably from that of a cantilevered beam or of a flat plate. Some numerical results can be found for the problem in the previously published literature, mainly obtained by using various finite element methods. The present paper is the first definitive study of the problem, presenting accurate non-dimensional frequency parameters for wide ranges of aspect ratio, shallowness ratio and thickness ratio. The analysis is based upon shallow shell theory. Numerical results are obtained by using the Ritz method, with algebraic polynomial trial functions for the displacements. Convergence is investigated, with attention being given both to the number of terms taken for each co-ordinate direction and for each of the three components of displacement. Accuracy of the results is also established by comparison with finite element results for shallow shells and with other accurate flat plate solutions.

  13. Vibration of cylindrical shells of bimodulus composite materials

    NASA Astrophysics Data System (ADS)

    Bert, C. W.; Kumar, M.

    1982-03-01

    A theory is formulated for the small amplitude free vibration of thick, circular cylindrical shells laminated of bimodulus composite materials, which have different elastic properties depending upon whether the fiber-direction strain is tensile or compressive. The theory used is the dynamic, shear deformable (moderately thick shell) analog of the Sanders best first approximation thin shell theory. By means of tracers, the analysis can be reduced to that of various simpler shell theories, namely Love's first approximation, and Donnell's shallow shell theory. As an example of the application of the theory, a closed form solution is presented for a freely supported panel or complete shell. To validate the analysis, numerical results are compared with existing results for various special cases. Also, the effects of the various shell theories, thickness shear flexibility, and bimodulus action are investigated.

  14. Magnetic stress anisotropy field in plated cylindrical Permalloy films.

    NASA Technical Reports Server (NTRS)

    Lutes, O. S.

    1971-01-01

    An analysis is made of the magnetic stress anisotropy field (Hks) arising from internal and external stress sources in plated-wire memory elements. The analysis takes into consideration circumferential composition variation and cylindrical geometry of the Permalloy film. Expressions are derived relating Hks to uniaxial film stress, average composition, and amplitude of composition variation. A result of particular importance is that even for average zeromagnetostrictive composition (ZMC) films, Hks may still make an appreciable contribution to the total anisotropy field if the composition is not uniform. Calculated Hks characteristics are shown to correlate with anisotropy field changes observed in annealing experiments. Examples are given to show the importance of composition uniformity in determining the stability of the anisotropy field. The utility of the analysis is extended by the inclusion of data expressing the inverse relation between anisotropy field and easy-axis dispersion in the film.

  15. Au cylindrical nanocup: A geometrically, tunable optical nanoresonator

    NASA Astrophysics Data System (ADS)

    Kovylina, M.; Alayo, N.; Conde-Rubio, A.; Borrisé, X.; Hibbard, G.; Labarta, A.; Batlle, X.; Pérez-Murano, F.

    2015-07-01

    The optical response of Au cylindrical metallic nanostructures (nanocups) with very thin walls is studied by means of finite difference time domain simulations. The simulations predict that, by changing the geometry of the nanocups, they behave as tunable optical nanoresonators with strong near-field enhancement. This opens up the possibility to use them simultaneously as container and field enhancer. Nanocups have been produced by an on-purpose designed fabrication route that combines nanoimprint lithography, definition of an intermediate hard mask, and metal lift-off. The fabrication route offers a manifold of supplementary advantages: thorough control of geometrical parameters; versatility of compositional design, including multishell nanocups; precise positioning of nanocups over the substrate; and low-cost and fast manufacturing of large areas of desirable density without loss of resolution, all processes being compatible with high throughput, low cost production, thus enabling future commercial applications.

  16. Light detonation wave in a cylindrical Z-pinch

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  17. Scaling Instability in Buckling of Axially Compressed Cylindrical Shells

    NASA Astrophysics Data System (ADS)

    Grabovsky, Yury; Harutyunyan, Davit

    2016-02-01

    In this paper, we continue the development of mathematically rigorous theory of "near-flip" buckling of slender bodies of arbitrary geometry, based on hyperelasticity. In order to showcase the capabilities of this theory, we apply it to buckling of axially compressed circular cylindrical shells. The theory confirms the classical formula for the buckling load, whereby the perfect structure buckles at the stress that scales as the first power of shell's thickness. However, in the case of imperfections of load, the theory predicts scaling instability of the buckling stress. Depending on the type of load imperfections, buckling may occur at stresses that scale as thickness to the power 1.5 or 1.25, corresponding to the lower and upper ends, respectively, of the historically accumulated experimental data.

  18. Processing of cylindrical hollow parts: piercing vs. extrusion

    NASA Astrophysics Data System (ADS)

    Comăneci, R.; Zaharia, L.; Nedelcu, D.; Bujoreanu, L. G.

    2015-11-01

    As work principle, piercing (P) and backward extrusion (BE) are similar deforming processes. However, working-load, strain and material flow are quiet different depending on real conditions. Since punch diameter d and workpiece diameter D are the defining parameters for both P and BE, there is a critical d/D ratio separating them as distinctive operations. To have a complete description of P and BE in terms of working load and yield pressure as function of d/D ratio, experimental tests and numerical predictions were conducted. Tridimensional finite element analysis (FEA) for different process designs (i.e. different d/D ratios) revealed distinctive evolutions of the material flow establishing the effective limits of P and BE respectively. Experimental and numerical results can be used in practice to provide estimates of working-load, critical yield pressure and tool dimensions for optimal P and BE in processing of cylindrical hollow parts.

  19. Apparatus and methods for determining balance of a cylindrical vehicle

    NASA Astrophysics Data System (ADS)

    Nugent, David M.

    1992-12-01

    Apparatus and methods for determining balance of a cylindrical vehicle are presented. The apparatus comprises a frame adapted for horizontal disposition, first and second support assemblies mounted on the frame for receiving the vehicle, first and second load cells mounted, respectively, on the first and second support assemblies. Upon placement of the vehicle on the support assemblies, the load cells are adapted to provide readings indicative of the weight of the vehicle. From these readings, the center of gravity of the vehicle may be determined . A torsion cell assembly is mounted on the frame and adapted for connection to the vehicle and for providing indications of righting moment and static heel of the vehicle.

  20. On the question of instabilities upstream of cylindrical bodies

    NASA Technical Reports Server (NTRS)

    Morkovin, M. V.

    1979-01-01

    In an attempt to understand the unsteady vortical phenomena in perturbed stagnation regions of cylindrical bodies, a critical review of the theoretical and experimental evidence was made. Current theory is revealed to be incomplete, incorrect, or inapplicable to the phenomena observed experimentally. The formalistic approach via the principle of exchange of instabilities should most likely be replaced by a forced-disturbance approach. Also, many false conclusions were reached by ignoring that treatment of the base and perturbed flows in Hiemenz coordinate eta is asymptotic in nature. Almost surely the techniques of matched asymptotic expansions are expected to be used to capture correctly the diffusive and vorticity amplifying processes of the disturbances regarding the mean-flow boundary layer and outer potential field as eta and y/diameter approach infinity. The serious uncertainties in the experiments are discussed in detail.

  1. The cylindrical magnetic Rayleigh-Taylor instability for viscous fluids

    SciTech Connect

    Chambers, K.; Forbes, L. K.

    2012-10-15

    This paper considers a cylindrical Rayleigh-Taylor instability, in which a heavy fluid surrounds a light fluid, and gravity is directed radially inwards. A massive object is located at the centre of the light fluid, and it behaves like a line dipole both for fluid flow and magnetic field strength. The initially circular interface between the two conducting fluids evolves into plumes, dependent on the magnetic and fluid dipole strengths and the nature of the initial disturbance to the interface. A spectral method is presented to solve the time-dependent interface shapes, and results are presented and discussed. Bipolar solutions are possible, and these are of particular relevance to astrophysics. The solutions obtained resemble structures of some HII regions and nebulae.

  2. Acoustics of a flanged cylindrical pipe using singular basis functions

    PubMed

    Amir; Matzner; Shtrikman

    2000-02-01

    The problem of acoustic radiation from a cylindrical pipe with an infinite flange has been discussed in a number of papers. The most common approach is to decompose the field inside the pipe over a basis of Bessel functions. A very large number of basis functions is usually required, with a large degree of ripple appearing as an artifact in the solution. In this paper it is shown that a close analysis of the velocity field near the corner yields a new family of functions, which are called "edge functions." Using this set of functions as test functions and applying the moment method on the boundary between the waveguide and free space, a solution is obtained with greatly improved convergence properties and no ripple. PMID:10687680

  3. Centrifugally driven thermal convection in a rotating porous cylindrical annulus

    NASA Astrophysics Data System (ADS)

    Kang, Jianhong; Chen, Xi; Fu, Ceji; Tan, Wenchang

    2013-04-01

    Thermal convection driven by centrifugal buoyancy in a rotating porous cylindrical annulus with conical end boundaries is investigated. The Darcy-Brinkman model with the addition of the time-derivative and Coriolis terms in a rotating frame of reference is applied to characterize the flow in porous media. The effects of the Darcy number and the Coriolis parameter on the thermal convective instability are analyzed by conducting linear stability analysis. Based on weakly nonlinear analysis, the Nusselt number is analytically determined in the neighborhood of onset points. The time evolution of convection patterns and the Nusselt number at high Rayleigh numbers are numerically simulated with the Galerkin method. Especially, the Nusselt number in the stage of stationary, time-periodic, and chaotic convection is obtained in our numerical simulation.

  4. Cylindrical microlasers and light emitting devices from conducting polymers

    SciTech Connect

    Frolov, S.V.; Fujii, A.; Chinn, D.; Vardeny, Z.V.; Yoshino, K.; Gregory, R.V.

    1998-06-01

    Substantially improved, photopumped polymer lasers are demonstrated using microrings and microdisks of various diameters D ranging from 5 to 200 {mu}m. Various cavity-dependent laser modes were observed, which for D{lt}10{mu}m were dominated by a single longitudinal mode with linewidth of less than 1 {Angstrom}. These microlasers were also characterized by Q of order 5000, low threshold excitation energy of order 100 pJ/pulse for pulse duration ranging from 100 ps to sub-{mu}s, and an abrupt increase in the emission directionality and polarization degree. Light emitting diodes with cylindrical geometry, fully compatible with these microlasers are also demonstrated. {copyright} {ital 1998 American Institute of Physics.}

  5. High-speed velocimetry inside imploding cylindrical liners

    NASA Astrophysics Data System (ADS)

    Dolan, Daniel; Lemke, Ray; Dalton, Devon; Harding, Eric; McBride, Ryan; Martin, Matthew; Blue, Brent; Walker, Scott

    2014-03-01

    Dynamic planar compression is conceptually simple but difficult to maintain at extreme pressure (>5 Mbar). Higher pressures are attainable with imploding cylindrical liners, using Photonic Doppler velocimetry (PDV) to track the liner interior. PDV measures Doppler shift directly--1 GHz of beat frequency for every 1 km/s of velocity--requiring a special ``leapfrog'' approach for liners traveling in excess of 20 km/s. Single-point and multi-point PDV measurements have been performed in aluminum, beryllium, and tantalum liners under ramp compression, and the technique can readily applied to other implosion experiments. Combined with electrical current diagnostics, these measurements test thermodynamic equations of state at pressures up to 10 MBar and beyond. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85.

  6. Multipactor Modeling in Cylindrical Dielectric-Loaded Accelerators

    SciTech Connect

    Power, John G.; Gold, Steven H.

    2006-11-27

    The observation of strong multipactor loading of a cylindrical dielectric-loaded accelerator (DLA) structure with an alumina liner was previously reported. Conventional multipactor loading of dielectric rf windows is due to a tangential rf electric field and generally saturates at a few percent power loss. However, this resonant single-surface multipactor is driven by a combination of normal and tangential rf electric fields, is a strong function of the incident power, and is capable of absorbing a large fraction (over 1/2) of the incident rf power. Since the initial report, several additional structures have been tested, fabricated from a variety of materials, some with low secondary-emission surface coatings, and having different physical dimensions. In this paper, we summarize the results of these tests and analyze the results in terms of a physical model of the multipactor phenomenon.

  7. Viscoplastic analysis of an experimental cylindrical thrust chamber liner

    NASA Technical Reports Server (NTRS)

    Arya, Vinod K.; Arnold, Steven M.

    1991-01-01

    A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5 sec. duration that corresponded to the experiments, and an extended loading cycle of 485.1 sec. duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

  8. Viscoplastic analysis of an experimental cylindrical thrust chamber liner

    NASA Technical Reports Server (NTRS)

    Arya, Vinod K.; Arnold, Steven M.

    1992-01-01

    A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5-s duration that corresponded to the experiments, and an extended loading cycle of 485.1 s duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location of failure in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

  9. Hydrodynamic stability of high-viscosity cylindrical liquid bridges

    NASA Astrophysics Data System (ADS)

    Nicolas, J. A.

    1992-08-01

    The hydrodynamic stability of cylindrical liquid bridges is studied in the asymptotic limit when viscosity is paramount. The problem has been solved analytically in terms of a series of biorthogonal eigenfunctions (the Papkovich-Fadle functions), by using an orthogonalization method devised by Smith (1952) for solving elasticity problems. It is found that the growth factor is real for all the values of the slenderness, leading to pure damping or growing motions for the stable or the unstable modes, respectively. This analysis is also valid when the viscous to capillary forces ratio is of order unity and the slenderness is close to the static stability limit. The results are compared with previous ones obtained from Rayleigh's viscous model for jets or from Cosserat's one-dimensional model, showing a very good agreement for long columns.

  10. Hydrodynamic stability of high-viscosity cylindrical liquid bridges

    NASA Astrophysics Data System (ADS)

    Nicolás, J. A.

    1992-08-01

    The hydrodynamic stability of cylindrical liquid bridges is studied in the asymptotic limit when viscosity is paramount. The problem has been solved analytically in terms of a series of biorthogonal eigenfunctions (the Papkovich-Fadle functions), by using an orthogonalization method devised by Smith [Aust. J. Sci. Res. 5, 227 (1952)] for solving elasticity problems. It is found that the growth factor is real for all the values of the slenderness, leading to pure damping or growing motions for the stable or the unstable modes, respectively. This analysis is also valid when the viscous to capillary forces ratio is of order unity and the slenderness is close to the static stability limit. The results are compared with previous ones obtained from Rayleigh's viscous model for jets or from Cosserat's one-dimensional model, showing a very good agreement for long columns.

  11. Photoacoustic section imaging with an integrating cylindrical detector

    NASA Astrophysics Data System (ADS)

    Gratt, Sibylle; Passler, Klaus; Nuster, Robert; Paltauf, Guenther

    2011-07-01

    A piezoelectric detector with cylindrical shape for photoacoustic section imaging is characterized. This detector is larger than the imaging object in direction of the cylinder axis, giving rise to its integrating properties. Its focal volume has the shape of a slice and the acquisition of signals for one section image requires rotation of an object about an axis perpendicular to this slice. Image reconstruction from the signals requires the application of the inverse Radon transform. It is shown that implementing the Abel transform is a suitable step in data processing, allowing speeding up the data acquisition since the scanning angle can be reduced. The resolution of the detector was estimated in directions perpendicular and parallel to the detection plane. An upper limit for the out of plane resolution is given and section images of a zebra fish are shown.

  12. Fast-electron transport in cylindrically laser-compressed matter

    NASA Astrophysics Data System (ADS)

    Perez, F.; Koenig, M.; Batani, D.; Baton, S. D.; Beg, F. N.; Benedetti, C.; Brambrink, E.; Chawla, S.; Dorchies, F.; Fourment, C.; Galimberti, M.; Gizzi, L. A.; Heathcote, R.; Higginson, D. P.; Hulin, S.; Jafer, R.; Koester, P.; Labate, L.; Lancaster, K.; Mac Kinnon, A. J.; McPhee, A. G.; Nazarov, W.; Nicolai, P.; Pasley, J.; Ravasio, A.; Richetta, M.; Santos, J. J.; Sgattoni, A.; Spindloe, C.; Vauzour, B.; Volpe, L.

    2009-12-01

    Experimental and theoretical results of relativistic electron transport in cylindrically compressed matter are presented. This experiment, which is a part of the HiPER roadmap, was achieved on the VULCAN laser facility (UK) using four long pulses beams (~4 × 50 J, 1 ns, at 0.53 µm) to compress a hollow plastic cylinder filled with plastic foam of three different densities (0.1, 0.3 and 1 g cm-3). 2D simulations predict a density of 2-5 g cm-3 and a plasma temperature up to 100 eV at maximum compression. A short pulse (10 ps, 160 J) beam generated fast electrons that propagate through the compressed matter by irradiating a nickel foil at an intensity of 5 × 1018 W cm-2. X-ray spectrometer and imagers were implemented in order to estimate the compressed plasma conditions and to infer the hot electron characteristics. Results are discussed and compared with simulations.

  13. Traveling circumferential unstable wave of cylindrical flame front

    NASA Astrophysics Data System (ADS)

    Trilis, A. V.; Vasiliev, A. A.; Sukhinin, S. V.

    2016-06-01

    The researches of stability of cylindrical front of deflagration combustion in an annular combustion chamber were made using phenomenological model. The flame front is described as discontinuity of gasdynamic parameters. It is considered that the combustion products are under chemical equilibrium. The combustible mixture and the combustion products are ideal gases. The velocity of deflagration combustion is determined using the Chapman-Jouget theory. It depends on the temperature of combustible mixture only. It is found that the combustible flame front is unstable for several types of small disturbances in the system Mechanics of instabilities are examined using both the numeric and analytical methods. The cases of evolution of the unstable waves rotating in circular channel are presented.

  14. Stress singularities at the vertex of a cylindrically anisotropic wedge

    NASA Technical Reports Server (NTRS)

    Delale, F.; Erdogan, F.; Boduroglu, H.

    1980-01-01

    The plane elasticity problem for a cylindrically anisotropic solid is formulated. The form of the solution for an infinite wedge shaped domain with various homogeneous boundary conditions is derived and the nature of the stress singularity at the vertex of the wedge is studied. The characteristic equations giving the stress singularity and the angular distribution of the stresses around the vertex of the wedge are obtained for three standard homogeneous boundary conditions. The numerical examples show that the singular behavior of the stresses around the vertex of an anisotropic wedge may be significantly different from that of the isotropic material. Some of the results which may be of practical importance are that for a half plane the stress state at r = 0 may be singular and for a crack the power of stress singularity may be greater or less than 1/2.

  15. Non-linear dynamic analysis of anisotropic cylindrical shells

    SciTech Connect

    Lakis, A.A.; Selmane, A.; Toledano, A.

    1996-12-01

    A theory to predict the influence of geometric non-linearities on the natural frequencies of an empty anisotropic cylindrical shell is presented in this paper. It is a hybrid of finite element and classical thin shell theories. Sanders-Koiter non-linear and strain-displacement relations are used. Displacement functions are evaluated using linearized equations of motion. Modal coefficients are then obtained for these displacement functions. Expressions for the mass, linear and non-linear stiffness matrices are derived through the finite element method. The uncoupled equations are solved with the help of elliptic functions. The period and frequency variations are first determined as a function of shell amplitudes and then compared with the results in the literature.

  16. The Moduli Space of Asymptotically Cylindrical Calabi-Yau Manifolds

    NASA Astrophysics Data System (ADS)

    Conlon, Ronan J.; Mazzeo, Rafe; Rochon, Frédéric

    2015-09-01

    We prove that the deformation theory of compactifiable asymptotically cylindrical Calabi-Yau manifolds is unobstructed. This relies on a detailed study of the Dolbeault-Hodge theory and its description in terms of the cohomology of the compactification. We also show that these Calabi-Yau metrics admit a polyhomogeneous expansion at infinity, a result that we extend to asymptotically conical Calabi-Yau metrics as well. We then study the moduli space of Calabi-Yau deformations that fix the complex structure at infinity. There is a Weil-Petersson metric on this space, which we show is Kähler. By proving a local families L 2-index theorem, we exhibit its Kähler form as a multiple of the curvature of a certain determinant line bundle.

  17. Potential of an emissive cylindrical probe in plasma

    NASA Astrophysics Data System (ADS)

    Fruchtman, A.; Zoler, D.; Makrinich, G.

    2011-08-01

    The floating potential of an emissive cylindrical probe in a plasma is calculated for an arbitrary ratio of Debye length to probe radius and for an arbitrary ion composition. In their motion to the probe the ions are assumed to be collisionless. For a small Debye length, a two-scale analysis for the quasineutral plasma and for the sheath provides analytical expressions for the emitted and collected currents and for the potential as functions of a generalized mass ratio. For a Debye length that is not small, it is demonstrated that, as the Debye length becomes larger, the probe potential approaches the plasma potential and that the ion density near the probe is not smaller but rather is larger than it is in the plasma bulk.

  18. Iterative Calculation of Plasma Density from a Cylindrical Probe Characteristic

    NASA Astrophysics Data System (ADS)

    Xu, Zhenfeng; Lu, Wenqi

    2013-08-01

    A novel method is proposed for treating cylindrical probe characteristics to obtain plasma density. The method consists of exponential extrapolation of the transitional part of the I-V curve to the floating potential for the ion saturation current, other than the existing theories which use the ion branch, and an iterative sheath thickness correction procedure for improved accuracy. The method was tested by treating Langmuir probe I-V characteristics obtained from inductively coupled Ar discharges at various pressures, and comparing the present results with those deduced by existing theories. It was shown that the plasma densities obtained by the present method are in good agreement with those calculated by the Allen-Boyd-Reynolds (ABR) theory, suggesting the effectiveness of the proposed method. Without need of manual setting and adjustment of fitting parameters, the method may be suitable for automatic and real time processing of probe characteristics.

  19. Attitude motion of a non-attitude-controlled cylindrical satellite

    NASA Technical Reports Server (NTRS)

    Wilkinson, C. K.

    1988-01-01

    In 1985, two non-attitude-controlled satellites were each placed in a low earth orbit by the Scout Launch Vehicle. The satellites were cylindrical in shape and contained reservoirs of hydrazine fuel. Three-axis magnetometer measurements, telemetered in real time, were used to derive the attitude motion of each satellite. Algorithms are generated to deduce possible orientations (and magnitudes) of each vehicle's angular momentum for each telemetry contact. To resolve ambiguities at each contact, a force model was derived to simulate the significant long-term effects of magnetic, gravity gradient, and aerodynamic torques on the angular momentum of the vehicles. The histories of the orientation and magnitude of the angular momentum are illustrated.

  20. The converging shock wave from a spherical or cylindrical piston

    NASA Astrophysics Data System (ADS)

    van Dyke, M.; Guttmann, A. J.

    1982-07-01

    A spherical or cylindrical cavity containing quiescent gas begins to contract at high constant radial speed, driving an axisymmetric shock wave inward to collapse at the center. We analyze the flow field by expanding the solution in powers of time, and calculate 40 terms by delegating the arithmetic to a computer. Analysis of the series for the radius of the shock wave confirms Guderley's local self-similar solution for the focusing, including recent refined values for his similarity exponent, and yields higher terms in his local expansion. In the range of adiabatic exponent where the Guderley solution has been shown not to be unique we find, in accord with a conjecture of Gel'fand, that the smallest admissible similarity exponent is realized.