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.
Kusaka, Yasuyuki; Duval, Jérome F L; Adachi, Yasuhisa
2010-12-15
We report an analysis for the morphology and breaking behavior of deposits of spherical latex particles (1 and 3.6 μm in diameter) at a cylindrical collector in a microfluidic channel fabricated by soft-lithography. In-situ observation of particle deposition over a large range of flow rate conditions evidence the relationship between deposit morphology and mode of particle transport toward the collector. For low Péclet number (Pe), particle deposits are nearly uniform all over the collector surface except at the rear where particles do not attach. Upon increase of Pe, deposits gradually adopt a columnar morphology at the collector stagnation point. These results are qualitatively consistent with previously reported Monte Carlo simulations of deposits formation in stagnation point flow systems. However, these simulations fail to quantitatively predict the observed deposition at the rear of the collector for sufficiently high flow rate. Additional deposit breaking experiments together with numerical evaluations of particle flux around the collector suggest that such "anomalous" deposition at large Pe is significantly governed by concomitant detachment of deposited particles at the stagnation point and the presence of recirculation flow at the collector rear. Finally, kinetics of deposition are discussed in connection with particle size-dependence of deposit breaking features.
Morphological stability of a solid-liquid interface growing in a cylindrical mold
NASA Astrophysics Data System (ADS)
Kato, Hiroshi
2016-12-01
The morphological stability of the planar interface of dilute alloys solidifying in a cylindrical mold is analyzed based on the perturbation model presented by Mullins and Sekerka under the assumption that the interface crosses the mold wall at right angles, to examine the effect of the inside diameter of the mold. When the interface grows in a mold of a larger inside diameter, the stability-instability criterion of the planar interface is coincident with the MS criterion. On the other hand, in a mold of a smaller diameter, the rippled interface is permitted to take a frequency of discrete values (the permitted frequency), and the planar interface grows stably under thermal conditions slightly exceeding the MS criterion. Also, there exists a minimum permitted frequency ωmin, and the critical inside diameter dc is derived from ωmin. When the alloy solidifies in a mold of an inside diameter less than dc, the interface grows stably under thermal conditions in which the MS model predicts unstable growth of the interface. Moreover, there is a lower limit dG in dc, and when the alloy solidifies in a mold of an inside diameter less than dG, the interface grows stably even at a zero temperature gradient in the liquid.
NASA Astrophysics Data System (ADS)
Zhang, Haobin; Xu, Jingjiang; Liu, Yu; Huang, Hui; Sun, Jie
2013-09-01
Three kinds of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) cylinders compacted with TATB raw materials, recrystallized near-spherical and platy TATB crystals are compared to investigate the effects of crystal quality and preferred orientation on their irreversible growth. The results show that the higher the crystal quality, the lower the irreversible volume growth. The compacted cylinders of raw material TATB, with the poorest crystal quality, possess more irreversible growth than those with recrystallized high quality TATB crystals. Irreversible growth of TATB cylinders are also affected by crystal preferred orientation. With the same crystal quality, crystal preferred orientation leads to anisotropic irreversible dimension growth, but has no effect on the volume expansion of TATB cylinders. By changing the crystal quality and preferred orientation, the deformation problem of TATB-based PBX explosives may be restricted.
Men's preferences for women's breast morphology in New Zealand, Samoa, and Papua New Guinea.
Dixson, Barnaby J; Vasey, Paul L; Sagata, Katayo; Sibanda, Nokuthaba; Linklater, Wayne L; Dixson, Alan F
2011-12-01
Sexual selection via mate choice may have influenced the evolution of women's breast morphology. We conducted an image-based questionnaire quantifying and comparing the preferences of men from Papua New Guinea (PNG), Samoa, and New Zealand (NZ) for images of women's breast size, breast symmetry, areola size, and areolar pigmentation. Results showed that men from PNG preferred larger breasts to a greater extent than men from Samoa and NZ, providing some support for the hypothesis that men from subsistence living cultures have a greater preference for morphological cues indicative of caloric reserves. Symmetrical breasts were most attractive to men in each culture. However, preferences were highest among NZ men, followed by men from Samoa, and were lowest among men from PNG. These results did not support the hypothesis that people living in higher pathogen environments have a greater preference for traits indicative of pathogen resistance and developmental stability. Large areolae were preferred among men from PNG, and to a lesser extent in Samoa, while in NZ men preferred medium-sized areolae. Thus, men's preferences for women's areolar size appear to be highly culturally specific. Darkly pigmented areolae were most attractive to men from Samoa and PNG, whereas men from NZ preferred areolae with medium pigmentation. These findings suggest that areolar pigmentation indicative of sexual maturity is preferred by men rather than lighter pigmentation, which may signal that a woman is in the early years of reproductive maturity. This study highlights the importance of cross-cultural research when testing the role of morphological cues in mate choice.
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.
Monai, Hiromu; Omori, Toshiaki; Okada, Masato; Inoue, Masashi; Miyakawa, Hiroyoshi; Aonishi, Toru
2010-01-01
Abstract Under physiological and artificial conditions, the dendrites of neurons can be exposed to electric fields. Recent experimental studies suggested that the membrane resistivity of the distal apical dendrites of cortical and hippocampal pyramidal neurons may be significantly lower than that of the proximal dendrites and the soma. To understand the behavior of dendrites in time-varying extracellular electric fields, we analytically solved cable equations for finite cylindrical cables with and without a leak conductance attached to one end by employing the Green's function method. The solution for a cable with a leak at one end for direct-current step electric fields shows a reversal in polarization at the leaky end, as has been previously shown by employing the separation of variables method and Fourier series expansion. The solution for a cable with a leak at one end for alternating-current electric fields reveals that the leaky end shows frequency preference in the response amplitude. Our results predict that a passive dendrite with low resistivity at the distal end would show frequency preference in response to sinusoidal extracellular local field potentials. The Green's function obtained in our study can be used to calculate response for any extracellular electric field. PMID:20159148
Prokop, Pavol; Fedor, Peter
2013-01-01
Human body morphology is thought to be correlated with sexual behaviour and sociosexuality (defined as an increased willingness to engage in sex without commitment) influences the perception of certain cues of physical attractiveness. Based on a sample of Slovak university students, we investigated relationships between 1) male and female mating success and reported body morphology (body mass index, BMI and waist-to-hip ratio, WHR) and 2) mate preference characteristics and mating success. Both males and females reported a similar number of long-term sexual partners and frequency of engaging in extra-pair copulation (EPC). The mating success of both sexes was positively mediated by self-perceived attractiveness. However, female BMI was inversely associated with mating success whereas increasing BMI was positively associated with male mating success (the total number of lifetime sexual partners) as well as with the likelihood of engaging in EPC. Unrestricted sociosexuality positively correlated with direct and indirect benefits from mating and negatively with the religious/political background of a potential mate and with the desire for a home/ children. These results confirm the hypothesis that human body morphology is associated with sexual behaviour and that cues of direct/indirect benefits in a potential mate positively correlate with sociosexuality.
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.
NASA Astrophysics Data System (ADS)
Lappa, Marcello
2016-10-01
The present analysis extends the author's earlier work [Lappa, Phys. Fluids 26, 093301 (2014), 10.1063/1.4893078] on the properties of patterns formed by the spontaneous accumulation and ordering of solid particles in certain types of flow. It is shown that under certain conditions, when subjected to vibrations to induce natural flow, nonisothermal fluids with dispersed solid particles are characterized by intervals of solid-pattern-forming behavior due to particle rearrangements preceded by intervals in which no recognizable structures of solid matter can be detected. The dynamics of these systems are highly nonlinear in nature. Because this family of particle attractors is known to exhibit strong sensitivity to the symmetry properties of the considered vibrated system and related geometrical constraints, the present study attempts to clarify the related dynamics in a geometry with curved walls (cylindrical enclosure). In particular, by assuming vibrations always directed perpendicularly to the imposed temperature gradient, we show that the morphology, spatial extension (percentage of physical volume occupied), separation (spatial distance), and mechanisms responsible for the formation of the resulting particle structures change significantly according to whether the temperature gradient is parallel or perpendicular to the symmetry axis of the cylinder. This indicates that the physics is not invariant with respect to 90° rotations in space of the specific forcing considered (direction of the imposed temperature gradient and associated perpendicular vibrations). Additional insights into the problem are obtained by assessing separately the influence played by the time-averaged (mean) and oscillatory effects. According to the numerical results, the intriguing diversity of particle agglomerates results from the different role or importance played by (curved or straight) boundaries in constraining particles and from the different structure and topology of the
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.
Gasparini, Clelia; Pilastro, Andrea; Evans, Jonathan P
2011-01-01
In internally fertilizing species male genitalia often show a higher degree of elaboration than required for simply transferring sperm to females. Among the hypotheses proposed to explain such diversity, sexual selection has received the most empirical support, with studies revealing that genital morphology can be targeted by both pre-and postcopulatory sexual selection. Until now, most studies have focused on these two episodes of selection independently. Here, we take an alternative approach by considering both components simultaneously in the livebearing fish, Poecilia reticulata. We allowed females to mate successively (and cooperatively) with two males and determined whether male genital length influenced the female's propensity to mate with a male (precopulatory selection, via female choice) and whether male genital size and shape predicted the relative paternity share of subsequent broods (postcopulatory selection, via sperm competition/cryptic female choice). We found no evidence that either episode of sexual selection targets male genital size or shape. These findings, in conjunction with our recent work exposing a role of genital morphology in mediating unsolicited (forced) matings in guppies, further supports our prior speculation that sexual conflict may be an important broker of genital evolution in this species.
Chen, Rongsheng; Hu, Liangsheng; Huo, Kaifu; Fu, Jijiang; Ni, Hongwei; Tang, Yan; Chu, Paul K
2011-12-16
Quasi-aligned cylindrical and conical core-shell nanofibers consisting of carbon shells and TiO(2) nanowire cores are produced in situ on Ti foils without using a foreign metallic catalyst and template. A cylindrical nanofiber has a TiO(2) nanowire core 30-50 nm in diameter and a 5-10 nm-thick cylindrical carbon shell, while in the conical nanostructure the TiO(2) nanowire core has a diameter of 20-40 nm and the thickness of the carbon shell varies from about 200 nm at the bottom to about 5 nm at the tip. Electrochemical analysis reveals well-defined redox peaks of the [Fe(CN)(6)](3-/4-) redox couple and heterogeneous charge-transfer rate constants of 0.010 and 0.062 cm s(-1) for the cylindrical and conical nanofibers, respectively. The coverage of exposed edge planes on the cylindrical and conical carbon shells is estimated to be 2.5 and 15.5 % respectively. The more abundant exposed edge planes on the conical nanofiber decrease the overpotential and increase the voltammetric resolution during electrochemical detection of uric acid and ascorbic acid. Our results suggest that the density of edge-plane sites estimated from Raman scattering is not necessarily equal to the density of exposed edge-plane sites, and only carbon electrodes with a large density of exposed edge planes or free graphene sheet ends exhibit better electrochemical performance.
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.
Peng, Wei-Hau; Chau, Yat-Pang; Lu, Kuo-Shyan; Kung, Hsiu-Ni
2016-01-01
Arecoline, a major alkaloid in areca nuts, is involved in the pathogenesis of oral diseases. Mammalian taste buds are the structural unit for detecting taste stimuli in the oral cavity. The effects of arecoline on taste bud morphology are poorly understood. Arecoline was injected intraperitoneally (IP) into C57BL/6 mice twice daily for 1-4 weeks. After arecoline treatment, the vallate papillae were processed for electron microscopy and immunohistochemistry analysis of taste receptor proteins (T1R2, T1R3, T1R1, and T2R) and taste associated proteins (α-gustducin, PLCβ2, and SNAP25). Body weight, food intake and water consumption were recorded. A 2-bottle preference test was also performed. The results demonstrated that 1) arecoline treatment didn't change the number and size of the taste buds or taste bud cells, 2) electron microscopy revealed the change of organelles and the accumulation of autophagosomes in type II cells, 3) immunohistochemistry demonstrated a decrease of taste receptor T1R2- and T1R3-expressing cells, 4) the body weight and food intake were markedly reduced, and 5) the sweet preference behavior was reduced. We concluded that the long-term injection of arecoline alters the morphology of type II taste bud cells, retards the growth of mice, and affects discrimination competencies for sweet tastants.
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
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.
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.
Leung, Ka-Ngo [Hercules, CA
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.
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.
Cylindrically symmetric wormholes
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.
Abadias, G.; Tse, Y.Y.; Guerin, Ph.; Pelosin, V.
2006-06-01
To clarify the underlying mechanisms that cause the preferred orientation in TiN films, we investigated the evolution with the thickness of the texture, surface morphology, and residual stress in TiN thin films deposited by dual ion beam sputtering. The films, with thickness h ranging from 50 to 300 nm, were grown on oxidized Si substrates using a primary Ar ion beam accelerated under 1.2 kV and different voltages V{sub a} of the (Ar+N{sub 2}) assistance beam: 25, 50, and 150 V. The influence of temperature was also investigated by varying the substrate temperature T{sub s} (25-300 deg. C) during growth or by performing a postdeposition annealing. X-ray diffraction (XRD) as well as transmission electron microscopy were used to study the microstructure and changes of texture with thickness h, while x-ray reflectivity and atomic force microscopy measurements were performed to determine the surface roughness. Residual stresses were measured by XRD and analyzed using a triaxial stress model. The crystallite group method was used for a strain determination of crystallites having different fiber axis directions, i.e., when a mixed texture exists. The surface roughness is found to increase with V{sub a} and T{sub s} due to the resputtering effect of the film surface. XRD reveals that for a small thickness (h{approx}50 nm) the TiN films exhibit a strong (002) texture independent of V{sub a}. For a larger thickness (100
NASA Astrophysics Data System (ADS)
Abadias, G.; Tse, Y. Y.; Guérin, Ph.; Pelosin, V.
2006-06-01
To clarify the underlying mechanisms that cause the preferred orientation in TiN films, we investigated the evolution with the thickness of the texture, surface morphology, and residual stress in TiN thin films deposited by dual ion beam sputtering. The films, with thickness h ranging from 50 to 300 nm, were grown on oxidized Si substrates using a primary Ar ion beam accelerated under 1.2 kV and different voltages Va of the (Ar+N2) assistance beam: 25, 50, and 150 V. The influence of temperature was also investigated by varying the substrate temperature Ts (25-300 °C) during growth or by performing a postdeposition annealing. X-ray diffraction (XRD) as well as transmission electron microscopy were used to study the microstructure and changes of texture with thickness h, while x-ray reflectivity and atomic force microscopy measurements were performed to determine the surface roughness. Residual stresses were measured by XRD and analyzed using a triaxial stress model. The crystallite group method was used for a strain determination of crystallites having different fiber axis directions, i.e., when a mixed texture exists. The surface roughness is found to increase with Va and Ts due to the resputtering effect of the film surface. XRD reveals that for a small thickness (h~50 nm) the TiN films exhibit a strong (002) texture independent of Va. For a larger thickness (100
Superhydrophobic cylindrical nanoshell array.
Park, Yong-Bum; Im, Maesoon; Im, Hwon; Choi, Yang-Kyu
2010-06-01
A superhydrophobic property was demonstrated on a cylindrical poly crystalline silicon nanoshell array due to its geometrical properties, even without a hydrophobic coating. The proposed structure showed superior water-repellency compared to a conventional pillar structure with an identical structural dimension. This superhydrophobic property is attributed to an air pillar that exists in the nanoshell. Through the calculation of capillary pressure, the stability of the air pillar was confirmed. Furthermore, a droplet impinging test was conducted on the fabricated cylindrical nanoshell array to verify the robust Cassie state of the proposed structure under a dynamic condition.
Static cylindrical matter shells
NASA Astrophysics Data System (ADS)
Arık, Metin; Delice, Özgür
2005-08-01
Static cylindrical shells composed of massive particles arising from matching of two different Levi-Civita space-times are studied for the shell satisfying either an isotropic or an anisotropic equation of state. We find that these solutions satisfy the energy conditions for certain ranges of the parameters.
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.…
Microfabricated cylindrical ion trap
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.
Abumandour, Mohamed M A; El-Bakary, Neveen E R
2017-06-01
The aim of this investigation was to describe the morphological characters of the tongue of two predatory birds with similar feeding preferences, i.e. the common kestrel and Hume's tawny owl. Descriptive information on the lingual morphology of these two birds, particularly Hume's tawny owl, is incomplete. We found that the lingual apex of the owl has an oval, concave, shovel-like form with a bifid lingual tip, while that of the kestrel has the shape of a horny tip-like spoon with a central process in addition to there being several filiform-like papillae on the dorsal surface of the apex and body. In the owl, the dorsal surface of the apex and body is subdivided into four U-shaped regions: lingual tip, two lateral regions and a median region. The two lateral regions are characterized by the presence of papillae and several openings of lingual glands, while the median region carries filiform-like papillae. In both birds, the papillary crest is located between the body and root. In the kestrel, there is an additional row of papillae rostral to crest, while in the owl there is a rostral lateral extension of papillae on the lateral lingual surface so the distribution pattern has a W-shape. In the kestrel, the posterior part of lingual body has several openings of glands, while the root lacks glands completely, although it has many taste buds. In the owl, the lingual root is folded and has a large number of gland openings. In the kestrel caudally to the glottis, there are two paramedian transverse rows of pharyngeal papillae with a pair of median huge papillae, while in the owl, there is only one transverse row of papillae. The dorsal and ventral lingual surfaces of both birds are lined with non-keratinized stratified squamous epithelium.
Cylindrical Mixing Layer Model in Stellar Jet
NASA Astrophysics Data System (ADS)
Choe, Seung-Urn; Yu, Kyoung Hee
1994-12-01
We have developed a cylindrical mixing layer model of a stellar jet including cooling effect in order to understand an optical emission mechanism along collimated high velocity stellar jets associated with young stellar objects. The cylindrical results have been calculated to be the same as the 2D ones presented by Canto & Raga(1991) because the entrainment efficiency in our cylindrical model has been obtained to be the same value as the 2D model has given. We have discussed the morphological and physical characteristics of the mixing layers by the cooling effect. As the jet Mach number increases, the initial temperature of the mixing layer goes high because the kinetic energy of the jet partly converts to the thermal energy of the mixing layer. The initial cooling of the mixing layer is very severe, changing its outer boundary radius. A subsequent change becomes adiabatic. The number of the Mach disks in the stellar jet and the total radiative luminosity of the mixing layer, based on our cylindrical calculation, have quite agreed with the observation.
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.
'Endurance' All Around (cylindrical)
NASA Technical Reports Server (NTRS)
2004-01-01
This 360-degree view of the terrain surrounding NASA's Mars Exploration Rover Opportunity was taken on the rover's 171st sol on Mars (July 17, 2004). It was assembled from images taken by the rover's navigation camera at a position referred to as 'site 33.' Opportunity had driven 11 meters (36 feet) into 'Endurance Crater.' The view is a cylindrical projection with geometrical seam correction.
Hilly Surroundings (cylindrical)
NASA Technical Reports Server (NTRS)
2004-01-01
This 360-degree view of the terrain surrounding NASA's Mars Exploration Rover Spirit was taken on the rover's 189th sol on Mars (July 15, 2004). It was assembled from images taken by the rover's navigation camera at a position referred to as Site 72, which is at the base of the 'West Spur' portion of the 'Columbia Hills.' The view is presented in a cylindrical projection with geometrical seam correction.
Gibert, Olivier; Dufour, Dominique; Giraldo, Andrés; Sánchez, Teresa; Reynes, Max; Pain, Jean-Pierre; González, Alonso; Fernández, Alejandro; Díaz, Alberto
2009-09-09
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
Cylindrical holographic radar camera
NASA Astrophysics Data System (ADS)
McMakin, Douglas L.; Sheen, David M.; Hall, Thomas E.; Severtsen, Ronald H.
1998-12-01
A novel personnel surveillance system has been developed to rapidly obtain 360 degree, full-body images of humans for the detection and identification of concealed threats. Detectable threats include weapons fabricated with metal, plastic, and ceramic, as well as explosive solids and liquids. This new system uses a cylindrical mechanical scanner to move a seven-foot, 384 element, Ka band (26 - 30 GHz) array circumferentially around a person in four to seven seconds. Low power millimeter-waves, which are nonionizing and not harmful to humans, are employed because they readily penetrate clothing barriers and reflect from concealed threats. The reflected waves provide information that is reconstructed into 3-D cylindrical holographic images with high-speed, digital signal processing (DSP) boards. This system is capable of displaying in an animation format eight, sixteen, thirty-two or sixty-four image frames at various aspect angles around the person under surveillance. This new prototype surveillance system is operational and is presently under laboratory testing and evaluation.
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).
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.
Cylindrical geometry hall thruster
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.
Lateral Ordering of Cylindrical Microdomains Under Solvent Vapor
Park, S.; Kim, B; Xu, J; Hofmann, T; Ocko, B; Russell, T
2009-01-01
The development of the morphology in asymmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) thin films in tetrahydrofuran (THF) vapor, a selective solvent for majority PS block, as a function of time was investigated by scanning force microscopy (SFM) and grazing incidence small-angle X-ray scattering (GISAXS). When the PS-b-P4VP films were spin-coated from a toluene/THF mixture onto a silicon substrate, cylindrical microdomains were found to be oriented normal to the surface. By annealing under the THF solvent vapor, the distribution of the size and center-to-center distance between the cylindrical microdomains were significantly narrowed. The orientation and grain size of the cylindrical microdomains in the annealed films were characterized using Moire analysis obtained from SFM scan. GISAXS was used to characterize the morphology of the entire film.
Lateral Ordering of Cylindrical Microdomains Under Solvent Vapor
Hofmann,T.; Ocko,B.; Park, S.; Kim, B.; Xu, J.; and Russell, T.P.
2009-01-28
The development of the morphology in asymmetric polystyrene-block-poly(4-vinylpyridine) (PSb- P4VP) thin films in tetrahydrofuran (THF) vapor, a selective solvent for majority PS block, as a function of time was investigated by scanning force microscopy (SFM) and grazing incidence small-angle X-ray scattering (GISAXS). When the PS-b-P4VP films were spin-coated from a toluene/THF mixture onto a silicon substrate, cylindrical microdomains were found to be oriented normal to the surface. By annealing under the THF solvent vapor, the distribution of the size and center-to-center distance between the cylindrical microdomains were significantly narrowed. The orientation and grain size of the cylindrical microdomains in the annealed films were characterized using Moire´ analysis obtained from SFM scan. GISAXS was used to characterize the morphology of the entire film.
Cylindrical quasi-Gaussian beams.
Mitri, F G
2013-11-15
Making use of the complex-source-point method in cylindrical coordinates, an exact solution representing a cylindrical quasi-Gaussian beam of arbitrary waist w(0) satisfying both the Helmholtz and Maxwell's equations is introduced. The Cartesian components of the electromagnetic field are derived stemming from different polarizations of the magnetic and electric vector potentials based on Maxwell's vectorial equations and Lorenz's gauge condition, without any approximations. Computations illustrate the theory for tightly focused and quasi-collimated cylindrical beams. The results are particularly useful in beam-forming design using high-aperture or collimated cylindrical laser beams in imaging microscopy, particle manipulation, optical tweezers, and the study of scattering, radiation forces, and torque on cylindrical structures.
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
Exact solutions for laminated composite cylindrical shells in cylindrical bending
NASA Technical Reports Server (NTRS)
Yuan, F. G.
1992-01-01
Analytic elasticity solutions for laminated composite cylindrical shells under cylindrical bending are presented. The material of the shell is assumed to be general cylindrically anisotropic. Based on the theory of cylindrical anisotropic elasticity, coupled governing partial differential equations are developed. The general expressions for the stresses and displacements in the laminated composite cylinders are discussed. The closed form solutions based on Classical Shell Theory (CST) and Donnell's (1933) theory are also derived for comparison purposes. Three examples illustrate the effect of radius-to-thickness ratio, coupling and stacking sequence. The results show that, in general, CST yields poor stress and displacement distributions for thick-section composite shells, but converges to the exact elasticity solution as the radius-to-thickness ratio increases. It is also shown that Donnell's theory significantly underestimates the stress and displacement response.
Shearfree cylindrical gravitational collapse
NASA Astrophysics Data System (ADS)
di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.
2009-09-01
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.
Cylindrical rotating triboelectric nanogenerator.
Bai, Peng; Zhu, Guang; Liu, Ying; Chen, Jun; Jing, Qingshen; Yang, Weiqing; Ma, Jusheng; Zhang, Gong; Wang, Zhong Lin
2013-07-23
We demonstrate a cylindrical rotating triboelectric nanogenerator (TENG) based on sliding electrification for harvesting mechanical energy from rotational motion. The rotating TENG is based on a core-shell structure that is made of distinctly different triboelectric materials with alternative strip structures on the surface. The charge transfer is strengthened with the formation of polymer nanoparticles on surfaces. During coaxial rotation, a contact-induced electrification and the relative sliding between the contact surfaces of the core and the shell result in an "in-plane" lateral polarization, which drives the flow of electrons in the external load. A power density of 36.9 W/m(2) (short-circuit current of 90 μA and open-circuit voltage of 410 V) has been achieved by a rotating TENG with 8 strip units at a linear rotational velocity of 1.33 m/s (a rotation rate of 1000 r/min). The output can be further enhanced by integrating more strip units and/or applying larger linear rotational velocity. This rotating TENG can be used as a direct power source to drive small electronics, such as LED bulbs. This study proves the possibility to harvest mechanical energy by TENGs from rotational motion, demonstrating its potential for harvesting the flow energy of air or water for applications such as self-powered environmental sensors and wildlife tracking devices.
Shearfree cylindrical gravitational collapse
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.
Cylindrically symmetric dust spacetime
NASA Astrophysics Data System (ADS)
Senovilla, José M. M.
2000-07-01
We present an explicit exact solution of Einstein's equations for an inhomogeneous dust universe with cylindrical symmetry. The spacetime is extremely simple but nonetheless it has surprising new features. The universe is `closed' in the sense that the dust expands from a big-bang singularity but recollapses to a big-crunch singularity. In fact, both singularities are connected so that the whole spacetime is `enclosed' within a single singularity of general character. The big-bang is not simultaneous for the dust, and in fact the age of the universe as measured by the dust particles depends on the spatial position, an effect due to the inhomogeneity, and their total lifetime has no non-zero lower limit. Part of the big-crunch singularity is naked. The metric depends on a parameter and contains flat spacetime as a non-singular particular case. For appropriate values of the parameter the spacetime is a small perturbation of Minkowski spacetime. This seems to indicate that flat spacetime may be unstable against some global non-vacuum perturbations.
Morphology selection via geometric frustration in chiral filament bundles.
Hall, Douglas M; Bruss, Isaac R; Barone, Justin R; Grason, Gregory M
2016-07-01
In assemblies, the geometric frustration of a locally preferred packing motif leads to anomalous behaviours, from self-limiting growth to defects in the ground state. Here, we demonstrate that geometric frustration selects the equilibrium morphology of cohesive bundles of chiral filaments, an assembly motif critical to a broad range of biological and synthetic nanomaterials. Frustration of inter-filament spacing leads to optimal shapes of self-twisting bundles that break the symmetries of packing and of the underlying inter-filament forces, paralleling a morphological instability in spherical two-dimensional crystals. Equilibrium bundle morphology is controlled by a parameter that characterizes the relative costs of filament bending and the straining of cohesive bonds between filaments. This parameter delineates the boundaries between stable, isotropic cylindrical bundles and anisotropic, twisted-tape bundles. We also show how the mechanical and interaction properties of constituent amyloid fibrils may be extracted from the mesoscale dimensions of the anisotropic bundles that they form.
Electron diffraction from cylindrical nanotubes
Qin, L.C. )
1994-09-01
Electron diffraction intensities from cylindrical objects can be conveniently analyzed using Bessel functions. Analytic formulas and geometry of the diffraction patterns from cylindrical carbon nanotubes are presented in general forms in terms of structural parameters, such as the pitch angle and the radius of a tubule. As an example the Fraunhofer diffraction pattern from a graphitic tubule of structure [18,2] has been simulated to illustrate the characteristics of such diffraction patterns. The validity of the projection approximation is also discussed.
Optimization of Cylindrical Hall Thrusters
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.
Optimization of Cylindrical Hall Thrusters
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. __________________________________________________
Optical inspection system for cylindrical objects
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.
Generalized offset surfaces of cylindrical surfaces
NASA Astrophysics Data System (ADS)
Georgiev, Georgi Hristov
2016-12-01
Cylindrical surfaces play an important role in geometric modeling and architecture. In this paper, we describe a way for constructing a new cylindrical surface from a given cylindrical surface. Our approach is based on the differential geometry of cylindrical surfaces and a generalization of the notion of offset surface. We examine the case of a similarity offset of an arbitrary cylindrical surface which is closely related to direct similarities of Euclidean 3-space. Some illustrative examples are included.
Cylindrical acoustic levitator/concentrator
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.
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.
Blast waves from cylindrical charges
NASA Astrophysics Data System (ADS)
Knock, C.; Davies, N.
2013-07-01
Comparisons of explosives are often carried out using TNT equivalency which is based on data for spherical charges, despite the fact that many explosive charges are not spherical in shape, but cylindrical. Previous work has shown that it is possible to predict the over pressure and impulse from the curved surface of cylindrical charges using simple empirical formulae for the case when the length-to-diameter ( L/ D) ratio is greater or equal to 2/1. In this paper, by examining data for all length-to-diameter ratios, it is shown that it is possible to predict the peak over pressure, P, for any length-to-diameter ratio from the curved side of a bare cylindrical charge of explosive using the equation P=K_PM(L/D)^{1/3}/R^3, where M is the mass of explosive, R the distance from the charge and K_P is an explosive-dependent constant. Further out where the cylindrical blast wave `heals' into a spherical one, the more complex equation P=C_1(Z^' ' })^{-3}+C_2(Z^' ' })^{-2}+C_3(Z^' ' })^{-1} gives a better fit to experimental data, where Z^' ' } = M^{1/3}(L/D)^{1/9}/D and C_1, C_2 and C_3 are explosive-dependent constants. The impulse is found to be independent of the L/ D ratio.
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…
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…
Hedrén, Mikael; Nordström, Sofie
2009-08-01
Organisms may be polymorphic within natural populations, but often the significance and genetic background to such polymorphism is not known. To understand the colour polymorphism expressed in the diploid marsh-orchids Dactylorhiza incarnata, morphological, habitat and genetic differentiation was studied in mixed populations on the island of Gotland, supplemented with genetic marker data from adjacent areas. A total of 398 accessions was investigated for plastid haplotype and three nuclear microsatellites. Morphometric data and vegetation data were obtained from a subset of 104 plants. No clear pattern of habitat differentiation was found among the colour morphs. Within sites, the yellow-flowered morph (ochroleuca) was slightly larger than the others in some flower characters, whereas the purple-flowered morph with spotted leaves (cruenta) was on average smaller. However, populations of the same colour morph differed considerably between sites, and there was also considerable overlap between morphs. Morphs were often genetically differentiated but imperfectly separated within sites. Most populations were characterized by significant levels of inbreeding. The ochroleuca morph constitutes a coherent, highly homozygous sublineage, although introgression from purple-flowered morphs occurs at some sites. The cruenta morph was genetically variable, although Gotland populations formed a coherent group. Purple-flowered plants with unspotted leaves (incarnata in the strict sense) were even more variable and spanned the entire genetic diversity seen in the other morphs. Colour polymorphism in D. incarnata is maintained by inbreeding, but possibly also by other ecological factors. The yellow-flowered morph may best be recognized as a variety of D. incarnata, var. ochroleuca, and the lack of anthocyanins is probably due to a particular recessive allele in homozygous form. Presence of spotted leaves is an uncertain taxonomic character, and genetic differentiation within D
Improved cylindrical mirror energy analyzer
NASA Astrophysics Data System (ADS)
Baranova, L. A.
2017-03-01
A study has been carried out of the electron-optical properties of improved design of the cylindrical mirror energy analyzer. Both external and internal electrodes of the analyzer are divided into three isolated parts, whereby the potentials on the individual parts can be regulated independently from each other. In symmetric operating mode at identical potentials on the side parts of the electrodes, a significant increase has been obtained in resolving power and light-gathering power of the analyzer compared to the standard design of the cylindrical mirror. In asymmetric operating mode, which is implemented in a linear potential distribution on the external electrode, the conditions have been found under which the linear dispersion of the analyzer increases several times.
Plastic buckling of cylindrical shells
Bandyopadhyay, K.; Xu, J.; Shteyngart, S.; Eckert, H.
1994-05-01
Cylindrical shells exhibit buckling under axial loads at stresses much less than the respective theoretical critical stresses. This is due primarily to the presence of geometrical imperfections even through such imperfections could be very small (e.g., comparable to thickness). Under internal pressure, the shell regains some of its buckling strength. For a relatively large radius-to-tickness ratio and low internal pressure, the effect can be reasonably estimated by an elastic analysis. However, for low radius-to-thickness ratios and greater pressures, the elastic-plastic collapse controls the failure load. In order to quantify the elastic-plastic buckling capacity of cylindrical shells, an analysis program was carried out by use of the computer code BOSOR5 developed by Bushnell of Lockheed Missiles and Space company. The analysis was performed for various radius-to- thickness ratios and imperfection amplitudes. The analysis results are presented in this paper.
Bremsstrahlung from cylindrical beta sources.
NASA Technical Reports Server (NTRS)
Harris, D. W.; Silverman, J.
1972-01-01
Refined experimental measurements of the bremsstrahlung number and energy fluxes from thick cylindrical sources of several nuclides are presented, dose rates calculated from experimental energy fluxes are compared with theoretical results based on Wyard's thick-target approximation, and experiments are correlated with both thick- and thin-target bremsstrahlung theory to obtain accurate values of bremsstrahlung yields. The data presented should prove useful for the design of radioisotope power supplies, particularly those used in spacecraft and in biological applications.
GRIPPING DEVICE FOR CYLINDRICAL OBJECTS
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)
Solutions of the cylindrical nonlinear Maxwell equations.
Xiong, Hao; Si, Liu-Gang; Ding, Chunling; Lü, Xin-You; Yang, Xiaoxue; Wu, Ying
2012-01-01
Cylindrical nonlinear optics is a burgeoning research area which describes cylindrical electromagnetic wave propagation in nonlinear media. Finding new exact solutions for different types of nonlinearity and inhomogeneity to describe cylindrical electromagnetic wave propagation is of great interest and meaningful for theory and application. This paper gives exact solutions for the cylindrical nonlinear Maxwell equations and presents an interesting connection between the exact solutions for different cylindrical nonlinear Maxwell equations. We also provide some examples and discussion to show the application of the results we obtained. Our results provide the basis for solving complex systems of nonlinearity and inhomogeneity with simple systems.
ERIC Educational Resources Information Center
National Commission on the Observance of International Women's Year, Washington, DC.
This document considers sexual preference as it specifically relates to women. Divided into two parts, the document presents a fact sheet about lesbianism and contains a workshop resource guide on sexual preference. The fact sheet, arranged in a question-answer format, focuses on the following concerns: (1) lesbianism as a woman's issue; (2) legal…
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.
Loads for pulsed power cylindrical implosion experiments
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.
Evaluation of transmitting performance of cylindrical polycapillary
NASA Astrophysics Data System (ADS)
Xiaoyan, Lin; Yude, Li; Guotai, Tan; Tianxi, Sun
2007-03-01
Based on a detailed ray-tracing code for capillary optics, a MATLAB program for the simulation of X-ray transmission in a cylindrical polycapillary is described. The simulated and experimental results for the spatial distributions and power density gain of the X-rays in the beam guided through a cylindrical polycapillary are in good agreement, and the results show that the spatial distribution of the X-rays in the beam guided through a cylindrical polycapillary is uneven.
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.
Chiral structures from achiral liquid crystals in cylindrical capillaries
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
Models of cylindrical bubble pulsation
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
Ingestion of cylindrical batteries and its management.
Tien, Tony; Tanwar, Sudeep
2017-01-17
In contrast to the ingestion of coin batteries, the ingestion of cylindrical batteries is an uncommon medical presentation. Owing to their larger size, cylindrical battery ingestion can lead to serious complications including intestinal haemorrhage, bowel obstruction, bowel perforation, peritonitis and even death. We discuss the case of a 17-year-old girl who presented after swallowing three cylindrical batteries. Her medical history included depression and previous battery ingestion that required surgical removal. During this presentation however, these ingested batteries were removed endoscopically at oesophagogastroduodenoscopy and ileocolonoscopy. The patient was subsequently discharged without complication. This paper discusses the complications and management of cylindrical battery ingestion. 2017 BMJ Publishing Group Ltd.
Casimir torque on a cylindrical gear
NASA Astrophysics Data System (ADS)
Vaidya, Varun
2014-08-01
I utilize effective field theory(EFT) techniques to calculate the Casimir torque on a cylindrical gear in the presence of a polarizable but neutral object and present results for the energy and torque as a function of angle for a gear with multiple cogs, as well as for the case of a concentric cylindrical gear.
Sequential effects in preference decision: Prior preference assimilates current preference.
Chang, Seah; Kim, Chai-Youn; Cho, Yang Seok
2017-01-01
An important factor affecting preference formation is the context in which that preference decision takes place. The current research examined whether one's preference formed for a previously presented stimulus influences the processing of a subsequent preference decision, henceforth referred to as the preference sequence effect. Using a novel sequential rating/judgment paradigm, the present study demonstrated the presence of a preference sequence effect using artistic photographs and face stimuli: A neutral stimulus was preferred more following a preferable stimulus than a less preferable stimulus. Furthermore, a similar trend was found even when the potential influence of response bias was controlled. These results suggest that an assimilative sequential effect exists even when sequential judgments are made solely based on one's subjective feeling; preference formed for a preceding stimulus modulates preference for a subsequent stimulus. This implies the need for a consideration of trial sequence as a factor creating a psychological context affecting the subsequent preference decisions.
Sequential effects in preference decision: Prior preference assimilates current preference
Chang, Seah; Kim, Chai-Youn
2017-01-01
An important factor affecting preference formation is the context in which that preference decision takes place. The current research examined whether one’s preference formed for a previously presented stimulus influences the processing of a subsequent preference decision, henceforth referred to as the preference sequence effect. Using a novel sequential rating/judgment paradigm, the present study demonstrated the presence of a preference sequence effect using artistic photographs and face stimuli: A neutral stimulus was preferred more following a preferable stimulus than a less preferable stimulus. Furthermore, a similar trend was found even when the potential influence of response bias was controlled. These results suggest that an assimilative sequential effect exists even when sequential judgments are made solely based on one’s subjective feeling; preference formed for a preceding stimulus modulates preference for a subsequent stimulus. This implies the need for a consideration of trial sequence as a factor creating a psychological context affecting the subsequent preference decisions. PMID:28817619
Sympatric speciation: perfume preferences of orchid bee lineages.
Jackson, Duncan E
2008-12-09
Female attraction to an environmentally derived mating signal released by male orchid bees may be tightly linked to shared olfactory preferences of both sexes. A change in perfume preference may have led to divergence of two morphologically distinct lineages.
Radially sandwiched cylindrical piezoelectric transducer
NASA Astrophysics Data System (ADS)
Lin, Shuyu; Fu, Zhiqiang; Zhang, Xiaoli; Wang, Yong; Hu, Jing
2013-01-01
A new type of radially sandwiched piezoelectric short cylindrical transducer is developed and its radial vibration is studied. The transducer is composed of a solid metal disk, a radially polarized piezoelectric ceramic short tube and a metal tube. The radial vibrations of the solid metal disk, the radially polarized piezoelectric tube and the metal tube are analyzed and their electromechanical equivalent circuits are introduced. Based on the mechanical boundary conditions among the metal disk, the piezoelectric tube and the metal tube, a three-port electromechanical equivalent circuit for the radially sandwiched transducer is obtained and the frequency equation is given. The theoretical relationship of the resonance and anti-resonance frequencies and the effective electromechanical coupling coefficient with the geometrical dimensions is analyzed. The radial vibration of the sandwiched transducer is simulated by using two different numerical methods. It is shown that the analytical resonance and anti-resonance frequencies are in good agreement with the numerically simulated results. The transducer is expected to be used in piezoelectric resonators, actuators and ultrasonic radiators in ultrasonic and underwater sound applications.
Thin cylindrical sheets of air
NASA Astrophysics Data System (ADS)
Thoroddsen, Sigurdur; Beilharz, Daniel; Guyon, Axel; Li, Er Qiang; Thoraval, Marie-Jean
2014-11-01
Drops impacting at low velocities onto a pool surface can stretch out thin hemispheric sheets of air. These air sheets can remain intact until they reach submicron thicknesses, whereby they rupture to form myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air-layers which can wrap around the entire drop to form anti-bubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread from the pinch-off from the nozzle. The air sheet can also wrap around these treads and remain stable over extended time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these air cylinders is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer.
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.
Spontaneous transition from flat to cylindrical solitons
Frycz, P.; Infeld, E. )
1989-07-24
Flat, cylindrical, and spherical soliton solutions to various model equations are known. Many of these exact solutions have been seen in numerical simulations. However, there are few simulations that actually show that exact flat solitons can break up into an array of exact cylindrical or spherical solitons and follow this on a step by step basis. This Letter presents the first of these two kinds of transition for the Zakharov-Kuznetsov equation governing ion acoustic solitons in strongly magnetized plasmas.
Object recognition using cylindrical harmonic filter.
Guerrero Bermúdez, Jáder
2004-06-28
We present the cylindrical harmonic filter for three-dimensional (3D) discrete correlation between range data. The filter guarantees invariance of the correlation peak intensity under target rotation around z-axis. It can be considered a harmonic decomposition, in cylindrical coordinates, of the 3D Fourier spectrum of the target. Some simulation results confirm the in-plane rotation invariance and the discrimination of the filter.
Damage experiments in cylindrical geometry update
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.
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.
NASA Astrophysics Data System (ADS)
Zhong, Sheng
uniform structural parameters, including the width of the micelles, width of the helix, and the pitch distance. There is no preference to the handedness, and both handednesses are observed, which is understandable since there are no chiral molecules or specific binding effects applied during the assembly. The helical structure is a product of kinetic process. Cryogenic transmission electron microscopy has been employed to monitor the morphological transformation. The study indicates there are two complicated but reproducible kinetic pathways to form the helices. One pathway involves the stacks of bended cylinders at early stages and the subsequent interconnection of these bended cylinders. Spherical micelles bud off of the interconnected nanostructure as the final step towards a defect-free helix. Another kinetic pathway shows very short helices are formed at first and aligned via head-to-tail style in the solution, and the subsequent sequential addition of these short helices results in prolonged mature helices. By using a ninhydrin-staining technique, amine molecules within the micellar corona are visualized and confirmed to preferentially locate in the inner side of the helical turns. The aggregation of amine molecules provides a strong attraction force due to electrostatic association between oppositely charged amine and acid groups and accumulation of hydrogen bonding among amine molecules to coil the cylindrical micelles into helical twisting features which are stabilized by the repulsion forces due to the chain packing frustration within the hydrophobic core, steric hindrance of amine molecules as well as the Coulomb repulsion of the excess charged amine groups. The formation mechanism of the helix offers the feasibility to manipulate the helical pitch distance and formation kinetics. The helical pitch distance can be enlarged or shrunk by varying the type and amount of amine molecules used in assembly, introducing inorganic salts, and changing pH. Luckily, the
NASA Astrophysics Data System (ADS)
Zitouni, Gley
1992-09-01
The propagation and stability of converging cylindrical shocks produced in an annular shock tube equipped with a three increment area contraction were investigated for various cylindrical chamber widths and two annular shock Mach numbers of 1.26 and 1.44. The method of characteristics, integrated using the Hartree scheme, was employed to determine the shock Mach number and pressure-time variations in the cylindrical chamber. These numerical values were verified experimentally by employing a set of piezoelectric pressure transducers placed at five different locations. In narrow cylindrical chambers, a new test section was used to determine the boundary layer effect on the shock strength. For a cylindrical chamber width of 2.5 mm, experimental results were found to be in excellent agreement with the inviscid numerical solution. For smaller widths, an empirical equation of the shock Mach number variation was developed. Stability of the converging shocks was examined from the series of spark shadowgraphs taken near the geometric center.
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.
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.
Design of tunable cylindrical dielectric nanoantenna
NASA Astrophysics Data System (ADS)
Devi, Inder; Reena; Kalra, Yogita; Sinha, R. K.
2016-09-01
A tunable cylindrical all dielectric optical nanoantenna has been proposed. A silicon nanocylinder of radius 60 nm and height 150 nm has been considered. The azimuthally symmetric, complete forward scattering at first Kerker's condition and backward scattering with minimum forward scattering at second generalized Kerker's condition in near infra-red region has been observed for the proposed design which makes silicon nanocylinder a promising candidate for optical nanoantenna applications. The effect of the dimensions of the dielectric nanocylinder on the scattering properties of the cylindrical nanoantenna has been analyzed using finite element method. We have analyzed that the variation in diameter of nanocylinder has great influence on the strength of interference of electric and magnetic dipolar resonances. Further, we have observed tuning ability of the cylindrical nanoantenna with respect to the variation in its radius.
Laser diode assembly including a cylindrical lens
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.
Cylindrical polarization symmetry for nondestructive nanocharacterization
NASA Astrophysics Data System (ADS)
Zhan, Qiwen
2003-07-01
Recently there is an increasing interest in laser beams with radial symmetry in polarization. Due to the cylindrical symmetry in polarization, these beams have unique focusing properties, which may find wide applications in a variety of nanometer scale applications, including high-resolution metrology, high-density data storage, and multi-functional optical microtool. In this paper, simple method of generating cylindrically polarized beams is presented and their potential applications to nondestructive nano-characterization are discussed. A high resolution surface plasmon microscope and a surface plasmon enhanced apertureless near-field scanning optical microscope are proposed. An automatic scanning microellipsometer that uses the cylindrical symmetry to enhance the signal-to-noise-ratio in high-spatial-resolution ellipsometric measurement will also be presented.
Beamtracking in cylindrical and cartesian coordinates
Schillinger, B.; Weiland, T.
1997-02-01
For the design of devices with circular optical axes, e.g. bending magnets or spectrometers, the use of cylindrical coordinates for field calculations could be favourable. Additionally, in case of applications like bending systems with nonorthogonal entry and exit faces, the coupling of cylindrical and cartesian coordinates improves the simulation of fringe fields. In this context we have implemented a consistent coupling between the two coordinate systems and have extended the tracking code of the electromagnetic simulator MAFIA to cylindrical coordinates. This extensions could be of interest for the calculation of transfer maps of ionoptical devices using the tracked particle orbit as reference trajectory and including fringe field effects in a more general manner. We will give a short introduction to the extensions and show some examples for bending systems with nonorthogonal entries. {copyright} {ital 1997 American Institute of Physics.}
Beamtracking in cylindrical and cartesian coordinates
Schillinger, B.; Weiland, T.
1997-02-01
For the design of devices with circular optical axes, e.g. bending magnets or spectrometers, the use of cylindrical coordinates for field calculations could be favourable. Additionally, in case of applications like bending systems with nonorthogonal entry and exit faces, the coupling of cylindrical and cartesian coordinates improves the simulation of fringe fields. In this context we have implemented a consistent coupling between the two coordinate systems and have extended the tracking code of the electromagnetic simulator MAFIA to cylindrical coordinates. This extensions could be of interest for the calculation of transfer maps of ionoptical devices using the tracked particle orbit as reference trajectory and including fringe field effects in a more general manner. We will give a short introduction to the extensions and show some examples for bending systems with nonorthogonal entries.
Dewetting processes in a cylindrical geometry.
Callegari, G; Calvo, A; Hulin, J P
2005-03-01
Dewetting of liquid films of water-glycerol solutions of different viscosities has been studied experimentally in PVC cylindrical tubes. In contrast with plane surfaces, the dewetting capillary number Ca(vd) increases with the film thickness ho over a large part of the experimental range and follows a same global trend independent of viscosity as a function of ho. This increase is only partly explained by variations of the capillary driving force predicted in a recent theoretical work for a cylindrical geometry. An additional explanation is suggested, based on different spatial distributions of the viscous dissipation in the dewetting bump in the planar and cylindrical geometries. This mechanism is investigated for films of different thicknesses in a numerical model assuming a polynomial variation of the liquid thickness with distance in the bump region.
Cylindrical Pulsons in Nonlinear Relativistic Wave Equations
NASA Astrophysics Data System (ADS)
Geicke, J.
1984-05-01
Numerical results to the Higgs scalar equation and the sine-Gordon equation with cylindrical symmetry are reported. Two separated energy regions are found where a Higgs kink develops into pulsons when reaching the origin r = 0, while only for higher energies a reflection is observed. The pulsons to both equations are studied in detail by modifying the initial kink shapes. In comparison with the spherical pulsons the cylindrical ones are extremely long-lived. For amplitudes slightly below half the distance between two (neighboured) vacua of the theories no decrease of the amplitudes and no perceivable radiation have been obtained by the numerical solution, examined during a time of order 1000. On the other hand, "heavy" sine-Gordon pulsons (with amplitudes 3π ~ 4π) are found to decay fast during a time t approx 100 in cylindrical symmetry.
Thermomechanical fracture on pressurized cylindrical vessels
NASA Astrophysics Data System (ADS)
Tzou, Robert D. Y.; Chiu, Kwong S.; Beraun, Jorge E.; Chen, Jinn Kuen
1998-09-01
This work studies the rapid fracture developed on the surface of a pressurized cylindrical vessel when heated by an intensified energy source. The primary concerns are the interactions between the rapid thermal expansion and the internal pressure that exerts on the interior surface. From a mechanical point of view, the thermal loading tends to develop a crack along the circumferential direction of the cylindrical vessel. The excessive internal pressure established within the cylindrical vessel, on the other hand, tends to develop a crack in the axial direction. Combination of the two mechanisms results in a capricious pattern of rapid fracture that needs to be fully understood in thermal processing. Special features in this work include the dynamics plasticity induced by the combined thermomechanical loading at short times, as well as the temperature-dependent thermomechanical properties that evolve in the load-time history.
Laser diode assembly including a cylindrical lens
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.
Current pulse effects on cylindrical damage experiments
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.
Self-referenced interferometer for cylindrical surfaces.
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.
Minerva: Cylindrical coordinate extension for Athena
NASA Astrophysics Data System (ADS)
Skinner, M. Aaron; Ostriker, Eve C.
2013-02-01
Minerva is a cylindrical coordinate extension of the Athena astrophysical MHD code of Stone, Gardiner, Teuben, and Hawley. 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.
Cylindrical roller bearings with profiled contacting surfaces
NASA Astrophysics Data System (ADS)
Creţu, S. S.
2017-02-01
An initial loading of cylindrical roller bearings in the elastic-plastic domain was performed to induce elastic shakedown phenomena able to change the basic profiles of both, rollers and raceways, which endorses a different value for the basic reference rating life. Fatigue life tests carried out on four lots of NJ206 cylindrical roller bearings revealed much higher values of L10 and Lm criteria for the bearings lots which experienced a suitable initial loading operation in the elastic-plastic domain. The reference rating lives, evaluated by using the lamina technique, confirmed the superiority of bearings lots which undergone an appropriate primary loading in the elastic-plastic domain.
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.
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.
Matching a static cylindrically symmetric elastic spacetime
NASA Astrophysics Data System (ADS)
Brito, I.; Carot, J.; Mena, F. C.; Vaz, E. G. L. R.
2012-07-01
We consider a static cylindrically symmetric spacetime with elastic matter and study the matching problem of this spacetime with a suitable exterior. For the exterior, we take the Levi-Civita spacetime and its generalization including a cosmological constant, the Linet-Tian spacetime. We show that the matching is only possible with the Linet-Tian solution.
Cylindrical Induction Melter Modicon Control System
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).
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.
High-energy-density cylindrical capacitors
NASA Technical Reports Server (NTRS)
Parker, R. D.; Zelik, J. A.
1979-01-01
Manufacturing technique produces high quality metalized-film cylindrical capacitors of energy density greater than 0.1 J/g uncased, using either 24-gage polyvinylidene flouride or 14-gage polycarbonate film. Components are wound wrinkle-free on hollow PTFE cores, using winding machine that applies constant dynamically controlled tension to film during winding operation.
Stationary convection in a cylindrical plasma
Gomberoff, L.; Hernandez, M.
1983-02-01
It is shown that viscosity and thermal conductivity leads to large-scale steady convection in a cylindrical current-carrying plasma, under the influence of a magnetic field satisfying (B/sub theta//B/sub z/)>>1. This state is the analog in a plasma of stationary convection in ordinary hydrodynamics.
Cylindrical coordinate representation for multiband Hamiltonians
NASA Astrophysics Data System (ADS)
Takhtamirov, Eduard
2012-10-01
Rotationally invariant combinations of the Brillouin zone-center Bloch functions are used as basis function to express in cylindrical coordinates the valence-band and Kane envelope-function Hamiltonians for wurtzite and zinc-blende semiconductor heterostructures. For cylindrically symmetric systems, this basis allows to treat the envelope functions as eigenstates of the operator of projection of total angular momentum on the symmetry axis, with the operator's eigenvalue conventionally entering the Hamiltonians as a parameter. Complementing the Hamiltonians with boundary conditions for the envelope functions on the symmetry axis, we present for the first time a complete formalism for efficient modeling and description of multiband electron states in low-dimensional semiconductor structures with cylindrical symmetry. To demonstrate the potency of the cylindrical symmetry approximation and establish a criterion of its applicability for actual structures, we map the ground and several excited valence-band states in an isolated wurtzite GaN quantum wire of a hexagonal cross-section to the states in an equivalent quantum wire of a circular cross-section.
Cylindrical plasmonic microcavity and its excitation
NASA Astrophysics Data System (ADS)
Haroyan, Hovhannes
2015-09-01
Cylindrical plasmonic microcavity structure is considered. The system consists of a cylindrically curved metallic structure placed above the flat metallic surface, supporting Surface Plasmon Polariton (SPP) propagation, and they are separated by dielectric gap. The active coupling between SPP resonant modes and SPP modes propagating over the flat metallic surface is demonstrated. The excitation efficiency dependence on structure's geometric and electrodynamics parameters of plasmonic microcavity is investigated. The possibility of controlling (or modulating) resonant SPP modes by varying different parameters such as minimal distance between cylindrical metallic and flat surfaces, relative permittivity of the dielectric gap, as well as working wavelengths are shown. The quality factor of metallic (as the metal is chosen gold: Au) cylindrical plasmonic microcavity is estimated Q ≍ 90, for fixed values of working wavelength: λ0=690 nm, relative permittivity of the dielectric media ɛd =3, and the radius of cylinder R=2.5 μm. Considered structure shows strong dependence on the relative permittivity of the dielectric media, the change of third decimal of ɛd brings to the significant change (up to three times) of microcavity excitation efficiency. Such phenomena can be successfully used for sensors construction based on plasmonic structures.
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
The sound field in a finite cylindrical shell
NASA Technical Reports Server (NTRS)
Junger, M. C.
1985-01-01
The sound field excited by vibrating boundaries in a finite cylindrical space, e.g., in a cylindrical shell, differs from the pressure distribution in an infinite cylindrical shell of comparable structural wavelength by the pressure diffracted by the end caps. The latter pressure component is comparable in magnitude to the pressure generated by the vibrating cylindrical boundary, but does not introduce additional resonances or antiresonances. Finally, a third pressure component associated with end cap vibrations is formulated.
Biomimetic surface structuring using cylindrical vector femtosecond laser beams
NASA Astrophysics Data System (ADS)
Skoulas, Evangelos; Manousaki, Alexandra; Fotakis, Costas; Stratakis, Emmanuel
2017-03-01
We report on a new, single-step and scalable method to fabricate highly ordered, multi-directional and complex surface structures that mimic the unique morphological features of certain species found in nature. Biomimetic surface structuring was realized by exploiting the unique and versatile angular profile and the electric field symmetry of cylindrical vector (CV) femtosecond (fs) laser beams. It is shown that, highly controllable, periodic structures exhibiting sizes at nano-, micro- and dual- micro/nano scales can be directly written on Ni upon line and large area scanning with radial and azimuthal polarization beams. Depending on the irradiation conditions, new complex multi-directional nanostructures, inspired by the Shark’s skin morphology, as well as superhydrophobic dual-scale structures mimicking the Lotus’ leaf water repellent properties can be attained. It is concluded that the versatility and features variations of structures formed is by far superior to those obtained via laser processing with linearly polarized beams. More important, by exploiting the capabilities offered by fs CV fields, the present technique can be further extended to fabricate even more complex and unconventional structures. We believe that our approach provides a new concept in laser materials processing, which can be further exploited for expanding the breadth and novelty of applications.
Biomimetic surface structuring using cylindrical vector femtosecond laser beams
Skoulas, Evangelos; Manousaki, Alexandra; Fotakis, Costas; Stratakis, Emmanuel
2017-01-01
We report on a new, single-step and scalable method to fabricate highly ordered, multi-directional and complex surface structures that mimic the unique morphological features of certain species found in nature. Biomimetic surface structuring was realized by exploiting the unique and versatile angular profile and the electric field symmetry of cylindrical vector (CV) femtosecond (fs) laser beams. It is shown that, highly controllable, periodic structures exhibiting sizes at nano-, micro- and dual- micro/nano scales can be directly written on Ni upon line and large area scanning with radial and azimuthal polarization beams. Depending on the irradiation conditions, new complex multi-directional nanostructures, inspired by the Shark’s skin morphology, as well as superhydrophobic dual-scale structures mimicking the Lotus’ leaf water repellent properties can be attained. It is concluded that the versatility and features variations of structures formed is by far superior to those obtained via laser processing with linearly polarized beams. More important, by exploiting the capabilities offered by fs CV fields, the present technique can be further extended to fabricate even more complex and unconventional structures. We believe that our approach provides a new concept in laser materials processing, which can be further exploited for expanding the breadth and novelty of applications. PMID:28327611
Self-Assembly of Supramolecular Composites under Cylindrical Confinement
NASA Astrophysics Data System (ADS)
Bai, Peter; Thorkelsson, Kari; Ercius, Peter; Xu, Ting
2014-03-01
Block copolymer (BCP) or BCP-based supramolecules are useful platforms to direct nanoparticle (NP) assemblies. However, the variety of NP assemblies is rather limited in comparison to those shown by DNA-guided approach. By subjecting supramolecular nanocomposites to 2-D cylindrical confinement afforded by anodic aluminum oxide membranes, a range of new NP assemblies such as stacked rings, and single and double helices can be readily obtained, as confirmed by TEM and TEM tomography. At low NP loadings (3 v%), the nanostructure conforms to the supramolecule morphology. However, at higher NP loadings (6-9 v%), the nanostructure deviates significantly from the morphology of supramolecular nanocomposites in bulk or in thin film, suggesting that frustrated NP packing, in addition to simple supramolecule templating, may play a significant role in the self-assembly process. The present studies demonstrate that 2-D confinement can be an effective means to tailor self-assembled NP structures and may open further opportunities to manipulate the macroscopic properties of NP assemblies.
Biomimetic surface structuring using cylindrical vector femtosecond laser beams.
Skoulas, Evangelos; Manousaki, Alexandra; Fotakis, Costas; Stratakis, Emmanuel
2017-03-22
We report on a new, single-step and scalable method to fabricate highly ordered, multi-directional and complex surface structures that mimic the unique morphological features of certain species found in nature. Biomimetic surface structuring was realized by exploiting the unique and versatile angular profile and the electric field symmetry of cylindrical vector (CV) femtosecond (fs) laser beams. It is shown that, highly controllable, periodic structures exhibiting sizes at nano-, micro- and dual- micro/nano scales can be directly written on Ni upon line and large area scanning with radial and azimuthal polarization beams. Depending on the irradiation conditions, new complex multi-directional nanostructures, inspired by the Shark's skin morphology, as well as superhydrophobic dual-scale structures mimicking the Lotus' leaf water repellent properties can be attained. It is concluded that the versatility and features variations of structures formed is by far superior to those obtained via laser processing with linearly polarized beams. More important, by exploiting the capabilities offered by fs CV fields, the present technique can be further extended to fabricate even more complex and unconventional structures. We believe that our approach provides a new concept in laser materials processing, which can be further exploited for expanding the breadth and novelty of applications.
Cylindrically converging shock and detonation waves
NASA Astrophysics Data System (ADS)
Matsuo, H.
1983-07-01
The non-self-similar implosion of cylindrical shock and detonation waves generated by an instantaneous energy release at a cylindrical wall is analyzed theoretically by the method of integral relations. The analysis shows that as the wave propagates towards the axis, the solutions tend to approach but never reach the self-similar implosion limit. The rate of approach appears to be slower than expected, and the region of applicability of the self-similar solution appears to be restricted to a very small region behind the front. This tendency is more pronounced for the detonation case. It is also demonstrated that for detonations where the initiation energy is negligible in comparison with the chemical energy, the Chapman-Jouguet detonation jump conditions apply at the front except near the axis and near the outer wall. The chemical heating in the detonation process increases the pressure and the temperature but considerably reduces the density near the front.
Damage experiments in a cylindrical geometry
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.
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.
Dynamic Buckling of Composite Cylindrical Shells
NASA Astrophysics Data System (ADS)
Cheng, Sai-Wei; Wang, Xiao-Jun
2016-05-01
Considering the effect of stress wave, the dynamic buckling governing equations and boundary conditions of composite cylindrical shells under axial step load are derived based on the Hamilton principle. The expression of radial displacement function along the circumferential direction is assumed since the cylindrical shell is closed. The solutions of the governing equations are obtained by the state-space technique. The determinant of the coefficient matrix must be equal to zero if the linear equations have a non-trivial solution. The relationship between the critical load and length and the influences of boundary conditions, modes, etc. on critical load are obtained by programming with MATLAB software before and after the reflection of stress wave.
Gravitational radiation from a cylindrical naked singularity
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.
Surface superconductivity in thin cylindrical Bi nanowire.
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.
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.
Investigation on Surface Roughness in Cylindrical Grinding
NASA Astrophysics Data System (ADS)
Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar
2011-01-01
Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.
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.
Experimental study of cylindrical air electrodes
NASA Astrophysics Data System (ADS)
Viitanen, M.; Lamminen, J.; Lampinen, M. J.
1991-11-01
The electrodes studied here are cylindrical and prepared to be placed inside the inner surface of a sintered brass tube, which is nickel-plated. Previously we have reported on the preparation of flat air electrodes and also on long run tests carried out with these electrodes. The electrode material was prepared by the so-called wet method to obtain a carbon dough which is easy to handle. The material preparation remains the same, but owing to the different geometrical shape, the preparation of the electrode itself is quite different. We have studied here the long-term performance of these new cylindrical air electrodes and at the same time measured the carbonate content of the electrolyte. We have also analyzed by comparative methods which property of the electrode lowers the performance after a fairly long period.
Variable-focus cylindrical liquid lens array
NASA Astrophysics Data System (ADS)
Zhao, Wu-xiang; Liang, Dong; Zhang, Jie; Liu, Chao; Zang, Shang-fei; Wang, Qiong-hua
2013-06-01
A variable-focus cylindrical liquid lens array based on two transparent liquids of different refractive index is demonstrated. An elastic membrane divides a transparent reservoir into two chambers. The two chambers are filled with liquid 1 and liquid 2, respectively, which are of different refractive index. The micro-clapboards help liquid 1, liquid 2 and the elastic membrane form a cylindrical lens array. Driving these two liquids to flow can change the shape of the elastic membrane as well as the focal length. In this design, the gravity effect of liquid can be overcome. A demo lens array of positive optical power is developed and tested. Moreover, a potential application of the proposed lens array for autostereoscopic 3D displays is emphasized.
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…
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…
Mixed FE analysis of viscoelastic cylindrical helixes
NASA Astrophysics Data System (ADS)
Arıbaş, Ü. N.; Omurtag, M. H.
2012-09-01
In this study, analysis of viscoelastic cylindrical helixes with circular and square cross section is investigated by using the mixed FEM based on Timoshenko beam theory. The Kelvin model is used for the viscoelastic behavior. The analysis is performed in the Laplace domain and the results are transformed back to time domain numerically by Modified Durbin algorithm. The outcome is quite satisfactory besides the necessary engineering precision.
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.
Aberrations of sphero-cylindrical ophthalmic lenses.
Malacara, Z; Malacara, D
1990-04-01
The authors have presented in two previous articles the graphic solutions resembling Tscherning ellipses, for spherical as well as for aspherical ophthalmic lenses free of astigmatism or power error. These solutions were exact, inasmuch as they were based on exact ray tracing, and not third-order theory as frequently done. In this paper sphero-cylindrical lenses are now analyzed, also using exact ray tracing. The functional dependence of the astigmatism and the power error for these lenses is described extensively.
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.
Spallation Damage Experiments in Cylindrical Geometry
2005-06-01
calculation after the onset of damage suspect. Figure 3. Calculated velocity (m/s) of liner to target impact as a function of radius (m). Figure...SPALLATION DAMAGE EXPERIMENTS IN CYLINDRICAL GEOMETRY Ann M. Kaul Los Alamos National Laboratory, P.O. Box 1663, MS-B259 Los Alamos, NM 87544...USA) Abstract Spallation damage is the process of damage in a ductile material caused by void nucleation, growth and coalescence due to
Cylindrical nonlinear Schroedinger equation versus cylindrical Korteweg-de Vries equation
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.
Jensen, Grethe V; Lund, Reidar; Narayanan, Theyencheri; Pedersen, Jan Skov
2016-06-02
Transformations between different micellar morphologies in solution induced by changes in composition, salt, or temperature are well-known phenomena; however, the understanding of the associated kinetic pathways is still limited. Especially for mixed surfactant systems, the micelles can take a very wide range of structures, depending on the surfactant packing parameter and other thermodynamic conditions. Synchrotron-based small-angle X-ray scattering (SAXS) in combination with fast mixing using a stopped-flow apparatus can give direct access to the structural kinetics on a millisecond time scale. Here, this approach is used to study the formation of cylindrical micelles after mixing two solutions with globular micelles of the nonionic surfactant dodecyl maltoside (DDM) and the anionic surfactant sodium dodecyl sulfate (SDS), respectively. Two separate processes were identified: (i) a transition in micellar shell structure, interpreted as exchange of surfactant molecules resulting in mixed globular micelles, and subsequently, (ii) fusion into larger, cylindrical structures.
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.
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.
Digital Perspective Correction For Cylindrical Holographic Stereograms
NASA Astrophysics Data System (ADS)
Jaffey, Stephen M.; Dutta, Kalyan
1983-04-01
This paper discusses digital perspective correction in the multiplex hologram,also known as Cross hologram or white light cylindrical holographic stereogram. It presents digital analogues of previously reported optical methods, and demonstrates the digital implementation of Benton's method. It introduces a non-linear remapping of the input views to compensate for a non-uniform color viewing position. Simulation results are included on the relative accuracy of different algorithms. Digital correction can be applied to both real and artificial objects such as computed tomography (CT) data.
High convergence implosion symmetry in cylindrical hohlraums
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.
Cullet Manufacture Using the Cylindrical Induction Melter
Miller, D. H.
2000-01-20
The base process for vitrification of the Am/Cm solution stored in F-canyon uses 25SrABS cullet as the glass former. A small portion of the cullet used in the SRTC development work was purchased from Corning while the majority was made in the 5 inch Cylindrical Induction Melter (CIM5). Task 1.01 of TTR-NMSS/SE-006, Additional Am-Cm Process Development Studies, requested that a process for the glass former (cullet) fabrication be specified. This report provides the process details for 25SrAB cullet production thereby satisfying Task 1.01.
Single-mode cylindrical graphene plasmon waveguide
NASA Astrophysics Data System (ADS)
Yang, Jianfeng; Yang, Jingjing; Huang, Ming
2016-08-01
A cylindrical graphene plasmon waveguide (CGPW) which consists of two rolled graphene ribbons, a dielectric core and a dielectric interlayer is proposed. An analytical model for the single-mode condition and cutoff frequency of high-order graphene surface plasmon (GSP) modes is presented and verified by finite element method (FEM) simulations. Single-mode operation region of CGPW is identified in the frequency-radius space. By varying the separation between two graphene sheets and the Fermi level of graphene, a large tunability of the mode behavior is also demonstrated. The proposed structure may provide a new freedom to manipulate GSPs, and would lead to novel applications in optics.
Enhanced Performance of Cylindrical Hall Thrusters
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.
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…
Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte
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.
On the computation of fundamental measure theory in pores with cylindrical symmetry
NASA Astrophysics Data System (ADS)
Mariani, Néstor J.; Mocciaro, Clarisa; Campesi, María A.; Barreto, Guillermo F.
2010-05-01
Classical density functional theories usually separate the formulation of the excess Helmholtz free energy in hard-body and energetic contributions. Fundamental measure theories (FMTs) have emerged as the preferred choice to account for the former contribution. The evaluation of geometrically weighted densities (convolutions) arisen in FMT for hard spheres in long cylindrical cavities is addressed in this paper. Previously, Malijevský [J. Chem. Phys. 126, 134710 (2007)] reported expressions containing elliptic integrals for the kernels of the convolutions involving scalar and vectorial weights. Here, the set of kernels is extended to second and third order tensorial weights that introduce desirable dimensional crossover properties to the evaluation of the excess free energy. An alternative formulation for the convolutions, which greatly facilitates their computation, is also proposed. Integrals of the original kernels arise in this way and a set of expressions for them, again expressed in terms of elliptic integrals, is presented here. With the aim of providing a computationally simple framework to evaluate equilibrium density profile with cylindrical symmetry, a procedure based on direct minimization of the discretized grand potential energy, rather than employing the Euler-Lagrange equilibrium conditions, is discussed and used to identify differences between two FMT formulations, including or not second order tensorial kernels in very narrow cylindrical pores.
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.
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).
Polymer Melt Diffusion inside Nanoscale Cylindrical Pores
NASA Astrophysics Data System (ADS)
Winey, Karen
Polymers in composites and inside porous media are frequently confined to spaces that are comparable to or even smaller than their mean end-to-end distances in the unconfined bulk state. Understanding the impact of nanoscale confinement on both polymer structure and dynamics is critical during processing and in applications. Anodized aluminum oxide (AAO) membranes with uniform cylindrical pores (diameters 18, 35, 55 or 80 nm) were filled with polystyrene (200 kDa) and then a thin layer of deuterated polystyrene was deposited on top. After annealing the concentration profile of the deuterated polymer was measured using elastic recoil detection and the center-of-mass polymer diffusion coefficient was determined. Melt diffusion is faster in AAO membranes with smaller pore diameters. This experimental finding is corroborated by coarse grain simulations with neutral interactions with the pore walls, although the increase is more pronounced in the simulations. Our simulations previously found that chain conformations slightly elongated parallel to the cylinder axis and compressed perpendicular to the cylinder and the number of entanglements per chain decreases as the cylinder diameter decreases. It is primarily the reduction in polymer entanglements that allows polymers to diffuse faster when the pore diameter is smaller in an athermal or weakly interacting system. Segmental dynamics have been measured using quasielastic neutron scattering. Polymer diffusion is cylindrical pores is now being studied at a fixed pore diameter as a function of molecular weight.
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.
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.
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.
Mantle flow reversals in cylindrical Earth models
NASA Astrophysics Data System (ADS)
Ghias, Sanaz R.; Jarvis, Gary T.
2007-12-01
We employ a two-dimensional model of mantle convection in a cylindrical shell to study the influence of curvature on the phenomenon of spontaneous flow reversal, which has been found previously only in plane layer models in Cartesian geometry. Our model includes rigidly moving plates, with weak zones at each end, and uniformly distributed internal heat sources. Surface plates in this model are passive in that their lateral velocities reflect the overall buoyancy in the underlying mantle and, at each time step, match the average surface velocity that would occur in the absence of plates. Our principal finding is that flow reversals, similar to those in plane layers, are also found in our cylindrical shell models, thereby attesting to the robustness of this feature. We conduct systematic investigations of the impact on the flow reversal behavior of varying degree of curvature, plate thickness, internal heating rate and aspect ratio of the convection cells. Flow reversals are driven by a build-up of internally heated material adjacent to a major mantle downwelling. When thermal instabilities develop in the upper boundary layer they develop into intermediate sinking plumes which disrupt the build-up of hot material near sinking plumes. Accordingly, parameter values which tend to stabilize the upper thermal boundary layer (low degree of curvature, high plate thickness, small aspect ratio and intermediate internal heating rate) favor regular flow reversals.
Low distortion laser welding of cylindrical components
NASA Astrophysics Data System (ADS)
Kittel, Sonja
2011-02-01
Automotive components are for the most part cylindrical and thus the weld seams are of radial shape. Radial weld seams are usually produced by starting at a point on the component's surface rotating the component resulting in an overlap zone at the start/end of the weld. In this research, it is shown that the component's distortion strongly depends on the overlap of weld start and end. A correlation between overlap zone and distortion is verified by an experimental study. In order to reduce distortion generated by the overlap zone a special optics is used which allows shaping the laser beam into a ring shape which is then focused on the cylindrical surface and produces a radial ring weld seam simultaneously by one laser pulse. In doing this, the overlap zone is eliminated and distortion can be reduced. Radial weld seams are applied on precision samples and distortion is measured after welding. The distortion of the precision samples is measured by a tactile measuring method and a comparison of the results of welding with the ring optics to reference welds is done.
Low distortion laser welding of cylindrical components
NASA Astrophysics Data System (ADS)
Kittel, Sonja
2010-09-01
Automotive components are for the most part cylindrical and thus the weld seams are of radial shape. Radial weld seams are usually produced by starting at a point on the component's surface rotating the component resulting in an overlap zone at the start/end of the weld. In this research, it is shown that the component's distortion strongly depends on the overlap of weld start and end. A correlation between overlap zone and distortion is verified by an experimental study. In order to reduce distortion generated by the overlap zone a special optics is used which allows shaping the laser beam into a ring shape which is then focused on the cylindrical surface and produces a radial ring weld seam simultaneously by one laser pulse. In doing this, the overlap zone is eliminated and distortion can be reduced. Radial weld seams are applied on precision samples and distortion is measured after welding. The distortion of the precision samples is measured by a tactile measuring method and a comparison of the results of welding with the ring optics to reference welds is done.
Motion of a Cylindrical Dielectric Boundary
Cheng, Li-Tien; Li, Bo; White, Michael; Zhou, Shenggao
2013-01-01
The interplay between geometry and electrostatics contributes significantly to hydrophobic interactions of biomolecules in an aqueous solution. With an implicit solvent, such a system can be described macroscopically by the dielectric boundary that separates the high-dielectric solvent from low-dielectric solutes. This work concerns the motion of a model cylindrical dielectric boundary as the steepest descent of a free-energy functional that consists of both the surface and electrostatic energies. The effective dielectric boundary force is defined and an explicit formula of the force is obtained. It is found that such a force always points from the solvent region to solute region. In the case that the interior of a cylinder is of a lower dielectric, the motion of the dielectric boundary is initially driven dominantly by the surface force but is then driven inward quickly to the cylindrical axis by both the surface and electrostatic forces. In the case that the interior of a cylinder is of a higher dielectric, the competition between the geometrical and electrostatic contributions leads to the existence of equilibrium boundaries that are circular cylinders. Linear stability analysis is presented to show that such an equilibrium is only stable for a perturbation with a wavenumber larger than a critical value. Numerical simulations are reported for both of the cases, confirming the analysis on the role of each component of the driving force. Implications of the mathematical findings to the understanding of charged molecular systems are discussed. PMID:23885130
Diagonal piezoelectric sensors on cylindrical shells
NASA Astrophysics Data System (ADS)
Li, Hua; Zhang, Xufang; Tzou, Hornsen
2017-07-01
Piezoelectric sensors are effective for distributed health monitoring and sensing of structures. The signals of piezoelectric sensors are related to the orientation of the sensors. In this study, a diagonal piezoelectric sensor is proposed for cylindrical shells. The sensor is made of a rectangular piezoelectric patch and diagonally attached on the shell surface; and piezoelectric actuators are used for excitation. An analytical model of the sensor is derived based on thin shell assumption with simply-supported boundary conditions. The orientation angle of the piezoelectric sensor is introduced as an independent variable. The proposed model consists of an integral term over the electrode area, which is divided into three regions for calculation. The sensing signal is decomposed into six components to evaluate the contributions of the strain components. Case studies on signals with respect to the orientation and aspect ratios are accomplished. The cylindrical shell with piezoelectric actuators and diagonal sensors is fabricated and tested under laboratory condition. Comparison of theoretical results with experimental data is conducted, and the model of the diagonal sensors is validated. The errors between the predictions and experimental results are less than 10% for all evaluated modes.
Scattering and radiation from cylindrically conformal antennas
NASA Astrophysics Data System (ADS)
Kempel, Leo Charles
Microstrip patch antennas offer considerable advantages in terms of weight, aerodynamic drag, cost, flexibility, and observability over more conventional protruding antennas. Two hybrid finite element methods are presented and are used to examine the scattering and radiation behavior of cylindrically conformal patches. In conjunction with a new divergence-free cylindrical shell element, the finite element-boundary integral method is shown to have low computational and memory requirements when compared with competing approaches. This method uses an efficient creeping wave series for the computation of the dyadic Green's function and a uniform surface mesh so that a fast Fourier transform may be used to reduce the computational and memory burden of the method. An alternative finite element-absorbing boundary condition approach incorporates a new conformal vector condition which minimizes the computational domain. The latter method is more flexible than the former because it can incorporate surface coatings and protruding antennas. Guidelines are established for minimal ABC displacement from the aperture. These two hybrid finite element methods are used to study the scattering, radiation, and input impedance of typical conformal antenna arrays. In particular, the effect of curvature and cavity size is examined for both discrete and wraparound antenna arrays.
Vibration analysis of bimodulus laminated cylindrical panels
NASA Astrophysics Data System (ADS)
Khan, K.; Patel, B. P.; Nath, Y.
2009-03-01
This paper deals with the flexural vibration behavior of bimodular laminated composite cylindrical panels with various boundary conditions. The formulation is based on first order shear deformation theory and Bert's constitutive model. The governing equations are derived using finite element method and Lagrange's equation of motion. An iterative eigenvalue approach is employed to obtain the positive and negative half cycle free vibration frequencies and corresponding mode shapes. A detailed parametric study is carried out to study the influences of thickness ratio, aspect ratio, lamination scheme, edge conditions and bimodularity ratio on the free vibration characteristics of bimodulus angle- and cross-ply composite laminated cylindrical panels. It is interesting to observe that there is a significant difference between the frequencies of positive and negative half cycles depending on the panel parameters. Through the thickness distribution of modal stresses for positive half cycle is significantly different from that for negative half cycle unlike unimodular case wherein the stresses at a particular location in negative half cycle would be of same magnitude but of opposite sign of those corresponding to positive half cycle. Finally, the effect of bimodularity on the steady state response versus forcing frequency relation is studied for a typical case.
Static, cylindrically symmetric strings in general relativity with cosmological constant
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.
Order-order transitions of diblock copolymer melts under cylindrical confinement
NASA Astrophysics Data System (ADS)
Liu, Meijiao; Li, Weihua; Wang, Xinping
2017-09-01
The self-assembly behavior of AB diblock copolymers under cylindrical confinement is investigated using the self-consistent field theory. We focus on the impact of the confinement on the order-order transitions of three-dimensional morphologies by constructing two types of phase diagrams with continuously varying block compositions. One type is with respect to the block composition and the immiscibility parameter for various pore sizes, in which the order-order transitions are shown to be strongly impacted by the pore curvature and thus largely different from the bulk ones. Note that the morphologies are categorized by the intrinsical geometry of their domains, i.e., that helical morphologies are regarded as one type of cylindrical phase. Another type of phase diagram is with respect to the block composition and the pore diameter, which exhibits a number of interesting order-order transitions, especially the transition sequence from a straight line of spheres, to one straight cylinder and stacked disks as the pore diameter increases. A critical point is observed at which the stability region of the straight cylinder vanishes and thereby the spheres transform into the stacked disks continuously. The mechanism of these phase transitions is rationalized in the context of the bulk factors as well as an additional factor, i.e., the competition between the spontaneous curvature of the copolymer and the imposed curvature by the nanopore.
Order-order transitions of diblock copolymer melts under cylindrical confinement.
Liu, Meijiao; Li, Weihua; Wang, Xinping
2017-09-21
The self-assembly behavior of AB diblock copolymers under cylindrical confinement is investigated using the self-consistent field theory. We focus on the impact of the confinement on the order-order transitions of three-dimensional morphologies by constructing two types of phase diagrams with continuously varying block compositions. One type is with respect to the block composition and the immiscibility parameter for various pore sizes, in which the order-order transitions are shown to be strongly impacted by the pore curvature and thus largely different from the bulk ones. Note that the morphologies are categorized by the intrinsical geometry of their domains, i.e., that helical morphologies are regarded as one type of cylindrical phase. Another type of phase diagram is with respect to the block composition and the pore diameter, which exhibits a number of interesting order-order transitions, especially the transition sequence from a straight line of spheres, to one straight cylinder and stacked disks as the pore diameter increases. A critical point is observed at which the stability region of the straight cylinder vanishes and thereby the spheres transform into the stacked disks continuously. The mechanism of these phase transitions is rationalized in the context of the bulk factors as well as an additional factor, i.e., the competition between the spontaneous curvature of the copolymer and the imposed curvature by the nanopore.
Performance of a hybrid cylindrical roller bearing
NASA Astrophysics Data System (ADS)
Schrader, Stephen M.
1992-08-01
A 206-size hybrid (ceramic/steel) cylindrical roller bearing was tested in MIL-L-23699 C oil at several speeds and loads. Heat-generation data was collected and subsequently correlated with bearing-analysis software. Bearing-cage slip data was also collected at various oil-flow rates, oil temperatures, and with both MIL-L-7808 J and MIL-L-23699 C oils. The hybrid bearing was tested in MIL-L-23699 C oil for for 25 hours at 2220 N radial load and 1.08 MDN shaft speed. The hybrid bearing technology demonstrated in the report is applicable to the Integrated High Performance Turbine Engine Technology Initiative.
Cathode Effects in Cylindrical Hall Thrusters
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.
Method for making generally cylindrical underground openings
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.
Naked singularity resolution in cylindrical collapse
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.
Electrochemical cell having cylindrical electrode elements
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.
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.
Scattering characteristics of simplified cylindrical invisibility cloaks.
Yan, Min; Ruan, Zhichao; Qiu, Min
2007-12-24
The previously reported simplified cylindrical linear cloak is improved so that the cloak's outer surface is impedance-matched to free space. The scattering characteristics of the improved linear cloak is compared to the previous counterpart as well as the recently proposed simplified quadratic cloak derived from quadratic coordinate transformation. Significant improvement in invisibility performance is noticed for the improved linear cloak with respect to the previously proposed linear one. The improved linear cloak and the simplified quadratic cloak have comparable invisibility performances, except that the latter however has to fulfill a minimum shell thickness requirement (i.e. outer radius must be larger than twice of inner radius). When a thin cloak shell is desired, the improved linear cloak is much more superior than the other two versions of simplified cloaks.
Asymptotic analysis of loaded, unstable, cylindrical resonators
Chitanvis, S.M. )
1991-09-01
I show that the solution of the electromagnetic equations for a loaded cavity with a large Fresnel number {ital F} ({ital F}{gt}100) can be obtained analytically. This asymptotic solution is obtained as a perturbation of the geometrical-optics solution, with edge-diffraction effects appearing as ripples of order 1/({ital F}){sup 1/2}. The basic technique is to obtain a series expansion of the relevant integrals in powers of 1/({ital F}){sup 1/2}. This scheme works even better if the laser is operating in the saturated regime. This method of solution represents an extension of the method of Butts and Avizonis (J. Opt. Soc. Am. {bold 68}, 1072 (1978)), which is applicable to empty, cylindrical, unstable resonators.
Cylindrical spreading due to downwind refraction.
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.
Cylindrical wormholes with positive cosmological constant
NASA Astrophysics Data System (ADS)
Richarte, Martín G.
2013-07-01
We construct cylindrical, traversable wormholes with finite radii by taking into account the cut-and-paste procedure for the case of cosmic string manifolds with a positive cosmological constant. Under reasonable assumptions about the equation of state of the matter located at the shell, we find that the wormhole throat undergoes a monotonous evolution provided it moves at a constant velocity. In order to explore the dynamical nonlinear behavior of the wormhole throat, we consider that the matter of the shell is supported by anisotropic Chaplygin gas, anti-Chaplygin gas, or a mixture of Chaplygin and anti-Chaplygin gases, implying that wormholes could suffer an accelerated expansion or contraction, but that oscillatory behavior seems to be forbidden.
Space charge emission in cylindrical diode
Torres-Córdoba, Rafael; Martínez-García, Edgar
2014-02-15
In this paper, a mathematical model to describe cylindrical electron current emissions through a physics approximation method is presented. The proposed mathematical approximation consists of analyzing and solving the nonlinear Poisson's equation, with some determined mathematical restrictions. Our findings tackle the problem when charge-space creates potential barrier that disable the steady-state of the beam propagation. In this problem, the potential barrier effects of electron's speed with zero velocity emitted through the virtual cathode happens. The interaction between particles and the virtual cathode have been to find the inter-atomic potentials as boundary conditions from a quantum mechanics perspective. Furthermore, a non-stationary spatial solution of the electrical potential between anode and cathode is presented. The proposed solution is a 2D differential equation that was linearized from the generalized Poisson equation. A single condition was used solely, throughout the radial boundary conditions of the current density formation.
MIRW properties of cylindrical holes array nanostructure
NASA Astrophysics Data System (ADS)
Wen, Chunchao; Fu, Yuegang; Dong, Tingting; Zhou, Jianhong; Guo, Xudong
2017-03-01
To improve mediate infrared wavelength (MIRW) light energy transferring efficiency, the optical properties of antireflection micro/nanostructure with cylindrical holes periodic array on incident angle, wavelength, polarized angle and azimuth orientation was researched based on finite time-domain difference (FDTD) method. Results shows that the antireflection characteristics can be promised in wider spectral range and lager incident angles. Reflectivity function also presents different features as polarization and azimuth angles changed. These structure parameters were optimized to be period of 1 µm, duty cycle of 0.85 and erosion height of 0.5 µm. Samples of the structure were fabricated by electron beam exposure and reaction ion etch technology on silicon substrate. Finally, the diverse shape effect of bionic moth-eye was explored to give respective ideal parameters suitable for MIRW.
Polymer translocation through a cylindrical channel
NASA Astrophysics Data System (ADS)
Wong, Chiu Tai Andrew; Muthukumar, M.
2008-04-01
A formalism of polymer translocation through a cylindrical channel of finite diameter and length between two spherical compartments is developed. Unlike previous simplified systems, the finite diameter of the channel allows the number of polymer segments inside the channel to be adjusted during translocation according to the free energy of possible conformations. The translocation process of a Gaussian chain without excluded volume and hydrodynamic interactions is studied using exact formulas of confinement free energy under this formalism. The free energy landscape for the translocation process, the distribution of the translocation time, and the average translocation time are presented. The complex dependencies of the average translocation time on the length and diameter of the channel, the sizes of the donor and receptor compartments, and the chain length are illustrated.
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.
Buckling of cylindrical panels under axial compression
NASA Technical Reports Server (NTRS)
Sobel, L. H.; Weller, T.; Agarwal, B. L.
1976-01-01
This paper investigates the effects of boundary conditions and panel width on the axially compressive buckling behavior of unstiffened, isotropic, circular cylindrical panels. Numerical results are presented for eight different sets of boundary conditions along the straight edges of the panels. For all sets of boundary conditions except one (SS1), the results show that the panel buckling loads monotonically approach the complete cylinder buckling load from above as the panel width is increased. Low buckling loads, sometimes less than half the complete cylinder buckling load, are found for simply supported panels with free in-plane edge displacements (SS1). It is observed that the prevention of circumferential edge displacement is the most important in-plane boundary condition from the point of view of increasing the buckling load; and that the prevention of edge rotation in the circumferential direction also significantly increases the buckling load.
Stresses in rotating composite cylindrical shells
NASA Astrophysics Data System (ADS)
Wang, James T.-S.; Lin, Chien-Chang
Stresses in composite cylindrical shells rotating with a constant speed about their longitudinal axis are analyzed. Each ply or ply group is treated as a separate thin layer of homogeneous and orthotropic material under the interfacial stresses as surface loading. There is no limitation on the total thickness of the shell. The circumferential stress, motivated by the conventional thin shell theory, is assumed to vary linearly through the thickness of the layer. The radial stress is determined in terms of the circumferential stress through the equilibrium condition, and an average compatibility condition through the thickness of the thin layer is used. Numerical results using the present analysis show nearly perfect agreement with the exact solution for homogeneous and isotropic cylinders. Some results for cylinders having orthotropic layers are presented for illustrative purposes.
Assaud, Loïc; Bochmann, Sebastian; Christiansen, Silke; Bachmann, Julien
2015-07-01
A new electrochemical setup and the associated procedures for growing ordered anodic aluminum oxide pore arrays on large surfaces are presented. The typical size of the samples is 14 × 14 cm(2). The most crucial experimental parameters that allow for the stabilization of the high-field procedures are a very efficient cooling of sample and electrolyte, as well as the initial ramping up of the voltage at an accurately defined rate. The morphology of the cylindrical, parallel alumina pores is similar to those obtained on smaller scales with standard setups. Our setup facilitates the availability of porous anodic alumina as a template system for a number of applications.
Hou, Zongyu; Wang, Zhe; Liu, Jianmin; Ni, Weidou; Li, Zheng
2014-06-02
Spark discharge has been proved to be an effective way to enhance the LIBS signal while moderate cylindrical confinement is able to increase the signal repeatability with limited signal enhancement effects. In the present work, these two methods were combined together not only to improve the pulse-to-pulse signal repeatability but also to simultaneously and significantly enhance the signal as well as SNR. Plasma images showed that the confinement stabilized the morphology of the plasma, especially for the discharge assisted process, which explained the improvement of the signal repeatability.
Wang, Fei; Gong, Haoran; Chen, Xi; Chen, C Q
2016-09-14
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.
NASA Astrophysics Data System (ADS)
Wang, Fei; Gong, Haoran; Chen, Xi; Chen, C. Q.
2016-09-01
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.
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
Iwaki, Takafumi; Shew, Chwen-Yang; Gumbs, Godfrey
2005-09-22
The structure of two-dimensional (2D) hard-sphere fluids on a cylindrical surface is investigated by means of the Ornstein-Zernike integral equation with the Percus-Yevick and the hypernetted-chain approximation. The 2D cylindrical coordinate breaks the spherical symmetry. Hence, the pair-correlation function is reformulated as a two-variable function to account for the packing along and around the cylinder. Detailed pair-correlation function calculations based on the two integral equation theories are compared with Monte Carlo simulations. In general, the Percus-Yevick theory is more accurate than the hypernetted-chain theory, but exceptions are observed for smaller cylinders. Moreover, analysis of the angular-dependent contact values shows that particles are preferentially packed anisotropically. The origin of such an anisotropic packing is driven by the entropic effect because the energy of all the possible system configurations of a dense hard-sphere fluid is the same. In addition, the anisotropic packing observed in our model studies serves as a basis for linking the close packing with the morphology of an ordered structure for particles adsorbed onto a cylindrical nanotube.
Cylindrical thin-shell wormholes supported by phantom energy
NASA Astrophysics Data System (ADS)
Eid, A.
2016-09-01
In the framework of Darmois-Israel formalism, the general equations describing the motion of cylindrical thin-shell wormholes supported by equation of state of phantom energy are derived. The linear perturbation approach is used to investigate the stability of a cylindrical thin-shell wormhole of a static solution.
Development of the Cylindrical Wire Electrical Discharge Machining Process.
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.
Fast calculation method for computer-generated cylindrical holograms.
Yamaguchi, Takeshi; Fujii, Tomohiko; Yoshikawa, Hiroshi
2008-07-01
Since a general flat hologram has a limited viewable area, we usually cannot see the other side of a reconstructed object. There are some holograms that can solve this problem. A cylindrical hologram is well known to be viewable in 360 deg. Most cylindrical holograms are optical holograms, but there are few reports of computer-generated cylindrical holograms. The lack of computer-generated cylindrical holograms is because the spatial resolution of output devices is not great enough; therefore, we have to make a large hologram or use a small object to fulfill the sampling theorem. In addition, in calculating the large fringe, the calculation amount increases in proportion to the hologram size. Therefore, we propose what we believe to be a new calculation method for fast calculation. Then, we print these fringes with our prototype fringe printer. As a result, we obtain a good reconstructed image from a computer-generated cylindrical hologram.
Cylindrical mirror multipass Lissajous system for laser photoacoustic spectroscopy
NASA Astrophysics Data System (ADS)
Hao, Lu-yuan; Qiang, Shi; Wu, Guo-rong; Qi, Li; Feng, Dang; Zhu, Qing-shi; Hong, Zhang
2002-05-01
A simple optical multiple reflection system is developed with two cylindrical concave mirrors at an appropriate spacing. The two cylindrical mirrors have different focal lengths and their principal sections are orthogonal. The alternate focusing of the two cylindrical mirrors at different direction keep the reflecting spots small. The reflecting spots fall on Lissajous patterns on the cylindrical mirrors. The mathematics for this optical system is described and the calculated coordinates of beam spots are very close matches of the experimental observations. The cylindrical mirror optical system is easy to construct and align, with a suitable method for obtaining long optical paths and a large number of passes in small volumes. In a photoacoustic spectrometer the beam family enhance the effective power in the photoacoustic cell and thus the signal-to-noise ratio of photoacoustic signal. An experimental result for photoacoustic spectrum of HDSe gas is given.
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.
Preferred Orientation in Polymer Fiber Scattering
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.
Order, topology and preference
NASA Technical Reports Server (NTRS)
Sertel, M. R.
1971-01-01
Some standard order-related and topological notions, facts, and methods are brought to bear on central topics in the theory of preference and the theory of optimization. Consequences of connectivity are considered, especially from the viewpoint of normally preordered spaces. Examples are given showing how the theory of preference, or utility theory, can be applied to social analysis.
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
Converging cylindrical shocks in ideal magnetohydrodynamics
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
Surface tension and long range corrections of cylindrical interfaces.
Bourasseau, E; Malfreyt, P; 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.
Surface tension and long range corrections of cylindrical interfaces
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.
Cylindrical shell buckling through strain hardening
Bandyopadhyay, K.; Xu, J.; Shteyngart, S.; Gupta, D.
1995-04-01
Recently, the authors published results of plastic buckling analysis of cylindrical shells. Ideal elastic-plastic material behavior was used for the analysis. Subsequently, the buckling analysis program was continued with the realistic stress-strain relationship of a stainless steel alloy which does not exhibit a clear yield point. The plastic buckling analysis was carried out through the initial stages of strain hardening for various internal pressure values. The computer program BOSOR5 was used for this purpose. Results were compared with those obtained from the idealized elastic-plastic relationship using the offset stress level at 0.2% strain as the yield stress. For moderate hoop stress values, the realistic stress-grain case shows a slight reduction of the buckling strength. But, a substantial gain in the buckling strength is observed as the hoop stress approaches the yield strength. Most importantly, the shell retains a residual strength to carry a small amount of axial compressive load even when the hoop stress has exceeded the offset yield strength.
Cylindrical gate valve apparatus and method
Hynes, J. H.; Morrill, C. D.
1985-04-30
A safety valve is disclosed which may be installed on an offshore wellhead above the tubing head and below the Christmas tree. The valve has a housing with upper and lower vertical passages and a lateral housing passage. A cylindrical gate is disposed within the lateral passage and includes a ''T'' shaped passage therein. The gate may be moved laterally and angularly within the lateral passage. During completion or workover of the well, the gate is moved laterally until the upper and lower vertical passages are in full open communication to run drills, hangers or other large diameter devices into the well via a BOP which may be attached to the top of the housing. During normal production, the gate may be laterally moved into the intersection of the vertical and lateral passages and the small through head part of the ''T'' passage serves to provide a vertical flow path through the production bore which is sealed off from the larger upper and lower vertical passages. Flow through side outlets in the housing is possible through the base of the ''T'' passage. The gate may be angularly moved to have production to the lateral outlets via the head part of the ''T'' when the base part of the ''T'' is aligned with production tubing. Should the need arise, the valve may be angularly rotated to a position where the fluid flow path of the production tubing is completely shut in.
Simulations of Indirectly Driven Cylindrical Implosions
NASA Astrophysics Data System (ADS)
Scott, J. M.; Beck, J. B.
1999-11-01
The growth of perturbations via the ablative Rayleigh-Taylor (ART) instability plays a significant role in the efficiency of ICF implosions. Experiments of radiation-driven cylindrical implosions have been performed to investigate the effects of the ablative Rayleigh-Taylor and Bell-Plesset instabilities in a convergent geometry [W. W. Hsing and N. M. Hoffman, Phys. Rev. Lett., 78, 3876 (1997)]. The ART instability at the ablation front of an ICF capsule is a dominant effect which degrades the implosion efficiency. Additionally, the Bell-Plesset effect, growth of a perturbation due to convergent geometry, further enhances implosion non-uniformity. New physics simulation codes are presently being developed at Los Alamos National Laboratory as part of ASCI (Advanced Super Computing Initiative). Importance is being placed upon validation of these computational codes with relevant Inertial Confinement Fusion (ICF) experiments. One of these codes, RAGE [Baltrusaitis, R.M., et al, Phys. Fluids 8, 2471 (1996)], an Eulerian based hydrodynamics code, utilizes adaptive mesh refinement (AMR) to resolve regions of physical interest in the computational domain. We will present comparisons of the perturbation growth from the RAGE code to the experimental data. This work was performed under the auspices of the U. S. Department of Energy by the Los Alamos National Laboratory under contract No. W-7405-Eng-36.
RAGE Simulations of Indirectly Driven Cylindrical Implosions
NASA Astrophysics Data System (ADS)
Scott, John; Beck, J. Bradley
2000-10-01
New physics simulation codes are being developed at Los Alamos National Laboratory as part of ASCI (Accelerated Strategic Computing Initiative). Importance is being placed upon validation of these computational codes with relevant inertial confinement fusion experiments. One of these codes, RAGE [Baltrusaitis, R.M., et al, Phys. Fluids 8, 2471 (1996)], an Eulerian based hydrodynamics code, utilizes adaptive mesh refinement (AMR) to resolve regions of physical interest in the computational domain. A recent addition to RAGE is a multi-group radiation-diffusion transport package. We performed simulations of indirectly-driven cylindrical implosion experiments measuring the effects of the ablative Rayleigh-Taylor and Bell-Plesset instabilities in a convergent geometry [W. W. Hsing and N. M. Hoffman, Phys. Rev. Lett., 78, 3876 (1997)]. In these experiments, the radiation drive contained a distinct M-shell component from the gold hohlraum that preheats the imploding cylinder, a difficult to simulate effect without multi-group radiation transport. Preheat places the target implosion on a higher adiabat reducing convergence and perturbation growth due to the Bell-Plesset effect. We compare the implosion trajectories and perturbation growth from the RAGE code to the experimental data. This work was performed under the auspices of the U. S. Department of Energy by the Los Alamos National Laboratory under contract No. W-7405-Eng-36.
Cylindrical Hall thrusters with permanent magnets
NASA Astrophysics Data System (ADS)
Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.
2010-11-01
The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction in 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 50-300 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.
Cylindrical Hall Thrusters with Permanent Magnets
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. __________________________________________________
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.
Cylindrical gravity currents in a rotating system
NASA Astrophysics Data System (ADS)
Wu, Ching-Sen; Dai, Albert
2016-11-01
This study aims at investigating the dynamical processes in the formation of stable cylindrical gravity currents, by a full-depth lock release, in a rotating system conducted by direct numerical simulations. The simulations reproduce the major features observed in the laboratory and provide more detailed flow information. Both the qualitative and quantitative measures are provided through the flow patterns and the predicted energy budgets. At the initial stage, during tenth of a revolution of the system, the Kelvin-Helmholtz vortices form and the flow structure maintain nearly axisymmetric. Afterwards, three-dimensionality of flow quickly develops and the outer rim of current breaks away from the body, which gives rise to the maximum dissipation rate in the system. The detached outer rim continues to propagate outward until a maximum radius of propagation is attained. Then the body of current exhibits a regularly contraction-relaxation motion in a period, the energy is transformed back and forth between potential energy and kinetic energy. With the use of high-resolution of numerical computations, the formation of lobe-and-cleft structure and swirling strength for the rotating gravity currents are clearly observed.
Technology Selections for Cylindrical Compact Fabrication
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.
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.
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.
Plasmons in topological insulator cylindrical nanowires
NASA Astrophysics Data System (ADS)
Iorio, P.; Perroni, C. A.; Cataudella, V.
2017-06-01
We present a theoretical analysis of Dirac magnetoplasmons in topological insulator nanowires. We discuss a cylindrical geometry where Berry phase effects induce the opening of a gap at the neutrality point. By taking into account surface electron wave functions introduced in previous papers and within the random phase approximation, we provide an analytical form of the dynamic structure factor. Dispersions and spectral weights of Dirac plasmons are studied with varying the radius of the cylinder, the surface doping, and the strength of an external magnetic field. We show that, at zero surface doping, interband damped plasmonlike excitations form at the surface and survive at low electron surface dopings (˜1010cm-2 ). Then, we point out that the plasmon excitations are sensitive to the Berry phase gap closure when an external magnetic field close to half quantum flux is introduced. Indeed, a well-defined magnetoplasmon peak is observed at lower energies upon the application of the magnetic field. Finally, the increase of the surface doping induces a crossover from damped interband to sharp intraband magnetoplasmons, which, as expected for large radii and dopings (˜1012cm-2 ), approach the proper limit of a two-dimensional surface.
Cylindrical array luminescent solar concentrators: performance boosts by geometric effects.
Videira, Jose J H; Bilotti, Emiliano; Chatten, Amanda J
2016-07-11
This paper presents an investigation of the geometric effects within a cylindrical array luminescent solar concentrator (LSC). Photon concentration of a cylindrical LSC increases linearly with cylinder length up to 2 metres. Raytrace modelling on the shading effects of circles on their neighbours demonstrates effective incident light trapping in a cylindrical LSC array at angles of incidence between 60-70 degrees. Raytrace modelling with real-world lighting conditions shows optical efficiency boosts when the suns angle of incidence is within this angle range. On certain days, 2 separate times of peak optical efficiency can be attained over the course of sunrise-solar noon.
Ultrafocused Electromagnetic Field Pulses with a Hollow Cylindrical Waveguide
NASA Astrophysics Data System (ADS)
Maurer, P.; Prat-Camps, J.; Cirac, J. I.; Hänsch, T. W.; Romero-Isart, O.
2017-07-01
We theoretically show that a dipole externally driven by a pulse with a lower-bounded temporal width, and placed inside a cylindrical hollow waveguide, can generate a train of arbitrarily short and focused electromagnetic pulses. The waveguide encloses vacuum with perfect electric conducting walls. A dipole driven by a single short pulse, which is properly engineered to exploit the linear spectral filtering of the cylindrical hollow waveguide, excites longitudinal waveguide modes that are coherently refocused at some particular instances of time, thereby producing arbitrarily short and focused electromagnetic pulses. We numerically show that such ultrafocused pulses persist outside the cylindrical waveguide at distances comparable to its radius.
Performance Characteristics of Cylindrical Target-type Thrust Reversers
NASA Technical Reports Server (NTRS)
Steffen, Fred W; Mcardle, Jack G
1956-01-01
From tests on cylindrical target-type thrust reversers, it was found that the reverser frontal area, lip angle, end-plate angle, and end-plate depth had important effects on reverse-thrust performance. Frontal area, reverser depth, lip angle, and end-plate angele had important effects on the spacing required for unrestricted nozzle flow. For reverse-thrust ratios greater than 64 percent, the reversed flow attached to the 7 degree cowl in quiescent air. Swept-type cylindrical reversers were generally unstable. The thrust-modulation characteristics of a cylindrical target-type thrust reverser were found to be satisfactory.
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.
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
2013-01-01
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
Cognitive impairment and preferences for current health
King, Joseph T; Tsevat, Joel; Roberts, Mark S
2009-01-01
Background We assessed preferences for current health using the visual analogue scale (VAS), standard gamble (SG), time trade-off (TTO), and willingness to pay (WTP) in patients with cerebral aneurysms, a population vulnerable to cognitive deficits related to aneurysm bleeding or treatment. Methods We measured VAS, SG, TTO, and WTP values for current health in 165 outpatients with cerebral aneurysms. We assessed cognitive impairment with the Mini Mental State Examination (MMSE; scores < 24 = cognitive impairment). We examined the distributions of preference responses stratified by cognitive status, and the relationship between preferences and cognitive impairment, patient characteristics, and aneurysm history. Results Eleven patients (7%) had MMSE scores < 24. The distribution of preferences responses from patients with cognitive impairment had greater variance (SG, 0.39 vs. 0.21, P = 0.001; TTO, 0.36 vs. 0.24, P = 0.017) and altered morphology (VAS, P = 0.012; SG, P = 0.023) compared to the responses of unimpaired patients. There was good correlation between most preference measures for unimpaired patients (VAS:TTO, rho = 0.19, P = 0.018; SG:TTO, rho = 0.36, P < 0.001; SG:WTP, rho = -0.33, P < 0.001) and a trend towards significance with another pairing (VAS:WTP, rho = 0.16, P = 0.054). In subjects with cognitive impairment, there was a significant correlation only between VAS and TTO scores (rho = 0.76, P = 0.023). Separate regression models showed that cognitive impairment was associated with lower preferences on the VAS (β = -0.12, P = 0.048), SG (β = -0.23, P = 0.002), and TTO (β = -0.17, P = 0.035). Conclusion Cognitive impairment is associated with lower preferences for current health in patients with cerebral aneurysms. Cognitively impaired patients have poor inter-preference test correlations and different response distributions compared to unimpaired patients. PMID:19134191
Multianode cylindrical proportional counter for high count rates
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.
Analysis of cylindrical thermo-acoustic radiation in gas
NASA Astrophysics Data System (ADS)
Yin, Yaping; Hu, Hanping
2017-04-01
During the past years, many experiments and theoretical studies on TA emission in flat and sphere have been carried out,but little attention is given to cylinder. In this work, by using a fully thermally-mechanically coupled TA model,the general expression for the cylindrical thermally-acoustic radiation in gas is derived to study the characteristics and regularities of cylindrical TA emission in detail. The flat amplitude -frequency response still exists for the TA emission on cylinder,and changes with the cylindrical radius as well as the distance from surface. Through the study of the cylindrical thermo-acoustic emission, we can get a better understanding of TA emission.
Multianode cylindrical proportional counter for high count rates
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.
Effect of Cellular Instability on the Initiation of Cylindrical Detonations
NASA Astrophysics Data System (ADS)
Han, Wen-Hu; Huang, Jin; Du, Ning; Liu, Zai-Gang; Kong, Wen-Jun; Wang, Cheng
2017-05-01
The direct initiation of detonations in one-dimensional (1D) and two-dimensional (2D) cylindrical geometries is investigated through numerical simulations. In comparison of 1D and 2D simulations, it is found that cellular instability has a negative effect on the 2D initiation and makes it more difficult to initiate a sustaining 2D cylindrical detonation. This effect associates closely with the activation energy. For the lower activation energy, the 2D initiation of cylindrical detonations can be achieved through a subcritical initiation way. With increasing the activation energy, the 2D cylindrical detonation has increased difficulty in its initiation due to the presence of unreacted pockets behind the detonation front and usually requires rather larger source energy. Supported by the National Natural Science Foundation of China under Grant Nos 91541206 and 91441131.
Mathematical model for characterizing noise transmission into finite cylindrical structures
NASA Astrophysics Data System (ADS)
Li, Deyu; Vipperman, Jeffrey S.
2005-02-01
This work presents a theoretical study of the sound transmission into a finite cylinder under coupled structural and acoustic vibration. Particular attention of this study is focused on evaluating a dimensionless quantity, ``noise reduction,'' for characterizing noise transmission into a small cylindrical enclosure. An analytical expression of the exterior sound pressure resulting from an oblique plane wave impinging upon the cylindrical shell is first presented, which is approximated from the exterior sound pressure for an infinite cylindrical structure. Next, the analytical solution of the interior sound pressure is computed using modal-interaction theory for the coupled structural acoustic system. These results are then used to derive the analytical formula for the noise reduction. Finally, the model is used to predict and characterize the sound transmission into a ChamberCore cylindrical structure, and the results are compared with experimental data. The effects of incidence angle and internal acoustic damping on the sound transmission into the cylinder are also parametrically studied. .
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.
Electron acceleration by a tightly focused cylindrical vector Gaussian beam
NASA Astrophysics Data System (ADS)
Xu, Jian; Yang, Zhen-Jun; Li, Jian-Xing; Zang, Wei-Ping
2017-02-01
We have studied the electron acceleration by a tightly focused cylindrical vector Gaussian beam. Different from the Lax series field, cylindrical vector Gaussian beams are vector-beam solutions of Maxwell’s equations and its focusing property can be numerically analyzed by the Richards-Wolf vectorial diffraction theory. Field differences exist between the cylindrical vector Gaussian beam and the Lax series field. The cylindrical vector Gaussian beam increases the asymmetry of the electromagnetic fields, which is more beneficial to the electron acceleration. When the beam waist falls down to the order of the wavelength, the high laser intensity zone is more proper to define the reflection, capture and transmission conditions of the electrons. The injection energy and the injected angle of the electron and the initial phase of the laser beam play important roles for the electron to enter and be trapped by the high laser intensity zone.
Cylindrical invisibility cloak with simplified material parameters is inherently visible.
Yan, Min; Ruan, Zhichao; Qiu, Min
2007-12-07
It was proposed that perfect invisibility cloaks can be constructed for hiding objects from electromagnetic illumination [J. B. Pendry, D. Schurig, and D. R. Smith, Science 312, 1780 (2006)10.1126/science.1125907]. The cylindrical cloaks experimentally demonstrated [D. Schurig, Science 314, 977 (2006)10.1126/science.1133628] and theoretically proposed [W. Cai, Nat. Photon. 1, 224 (2007)10.1038/nphoton.2007.28] have however simplified material parameters in order to facilitate easier realization as well as to avoid infinities in optical constants. Here we show that the cylindrical cloaks with simplified material parameters inherently allow the zeroth-order cylindrical wave to pass through the cloak as if the cloak is made of a homogeneous isotropic medium, and thus visible. To all high-order cylindrical waves, our numerical simulation suggests that the simplified cloak inherits some properties of the ideal cloak, but finite scatterings exist.
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)
16. DETAIL OF SOUTH ABUTMENT, SHOWING GIRDER, CYLINDRICAL FIXED BEARING ...
16. DETAIL OF SOUTH ABUTMENT, SHOWING GIRDER, CYLINDRICAL FIXED BEARING SHOE AND LATERAL BRACING. VIEW TO SOUTHWEST. - Rio Puerco Bridge, Mainline Road, spanning Rio Puerco, Holbrook, Navajo County, AZ
20. OBLIQUE VIEW, VANE LINE RELAY, CYLINDRICAL HOUSING, NEW HAVEN ...
20. OBLIQUE VIEW, VANE LINE RELAY, CYLINDRICAL HOUSING, NEW HAVEN SIGNAL SHOP - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT
19. FRONT VIEW, VALVE LINE RELAY, CYLINDRICAL HOUSING, NEW HAVEN ...
19. FRONT VIEW, VALVE LINE RELAY, CYLINDRICAL HOUSING, NEW HAVEN SIGNAL SHOP - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT
Patient preferences for dentists.
Furnham, Adrian; Swami, Viren
2009-03-01
A representative British sample of 257 adults completed a questionnaire in which they indicated their preference for eight dentists stratified by sex, age, and training location. These data were analysed in relation to participants' own sex and age, the latter stratified by a median split. A mixed analysis of variance indicated two main effects: a preference for younger (rather than older) dentists and dentists trained in Britain (rather than in Asia). There were also a significant two-way interaction between dentist age and training location: for the British-trained there was a preference for younger dentists, whereas for the Asian-trained there was a preference for older dentists. Limitations of the study design are discussed in conclusion.
Student Preferences in Typography.
ERIC Educational Resources Information Center
Bell, Richard C.; Sullivan, James L. F.
1981-01-01
Describes a study in which 245 university students ranked their preferences among typographical variants of typeface, size, emphasis, and interline space in 16 paragraphs. Six references are listed. (CHC)
High speed cylindrical rolling element bearing analysis 'CYBEAN' - Analytic formulation
NASA Technical Reports Server (NTRS)
Kleckner, R. J.; Pirvics, J.; Castelli, V.
1979-01-01
This paper documents the analytic foundation and software architecture for the computerized mathematical simulation of high speed cylindrical rolling element bearing behavior. The software, CYBEAN (CYlindrical BEaring ANalysis), considers a flexible, variable geometry outer ring, EHD films, roller centrifugal and quasidynamic loads, roller tilt and skew, mounting fits, cage and flange interactions. The representation includes both steady state and time transient simulation of thermal interactions internal to and coupled with the surroundings of the bearing. A sample problem illustrating program use is presented.
The DART Cylindrical, Infrared, 1 Meter Membrane Reflector
NASA Technical Reports Server (NTRS)
Morgan, Rhonda M.; Agnes, Greg S.; Barber, Dan; Dooley, Jennifer; Dragovan, Mark; Hatheway, Al E.; Marcin, Marty
2004-01-01
The Dual Anamorphic Reflector Telescopes (DART) is an architecture for large aperture space telescopes that enables the use of membranes. A membrane can be readily shaped in one direction of curvature using a combination of boundary control and tensioning, yielding a cylindrical reflector. Two cylindrical reflectors (orthogonal and confocal) comprise the 'primary mirror' of the telescope system. The aperture is completely unobstructed and ideal for infrared and high contrast observations.
The DART Cylindrical, Infrared, 1 Meter Membrane Reflector
NASA Technical Reports Server (NTRS)
Morgan, Rhonda M.; Agnes, Greg S.; Barber, Dan; Dooley, Jennifer; Dragovan, Mark; Hatheway, Al E.; Marcin, Marty
2004-01-01
The Dual Anamorphic Reflector Telescopes (DART) is an architecture for large aperture space telescopes that enables the use of membranes. A membrane can be readily shaped in one direction of curvature using a combination of boundary control and tensioning, yielding a cylindrical reflector. Two cylindrical reflectors (orthogonal and confocal) comprise the 'primary mirror' of the telescope system. The aperture is completely unobstructed and ideal for infrared and high contrast observations.
Preference for newspaper size.
Tsang, Steve N H; Hoffmann, Errol R; Chan, Alan H S
2014-05-01
The past few years has seen a change in the size of newspapers, with publishers moving to a smaller size format. Five 'standard' newspaper sizes are used in different countries: Broadsheet, Rhensch, Tabloid, Tall Tabloid and Berliner. These papers vary in both width and height of pages and hence there are implications for human reading comfort, which may be dependent on reading location such as on a lounge chair or on a train. Experiments were carried out to determine preferences for the different sizes and to relate these preferences to the geometric characteristics of the newspapers. For both comfortable and cramped/uncomfortable reading conditions, the rank order of preference for paper types was, from least to most-preferred, Broadsheet, Rhensch, Berliner, Tall Tabloid and Tabloid. Preferences were much stronger when determined in cramped/uncomfortable reading conditions, where most comparisons were significantly different. There was good correlation between participant ratings on several scales and preference, where most factors were related to comfort of holding and controlling the paper. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.
Quantification of the geometrical parameters of non-cylindrical folds
NASA Astrophysics Data System (ADS)
Zulauf, G.; Zulauf, J.; Maul, H.
2017-07-01
The geometrical parameters of natural folds are used by structural geologists to estimate finite strain and rheological properties of deformed rocks. The relation between geometry and rheology is well understood in cases of cylindrical folds, but is still limited for non-cylindrical folds, although the latter are frequent in nature. The sparsity of quantitative geometrical data of non-cylindrical folds can be explained by the small number of 3D exposures and by the lack of robust methods to quantify their geometrical parameters in 3D space. We present a new workflow, which can be used to quantify geometrical parameters of non-cylindrical folds. 3D fold geometry is described using fold wavelength, λ, arc-length, L, and amplitude, A. As most natural folds do not show ideal shapes, but are affected by various types of discontinuities, the new procedure is not fully automatic, but requires the manual selection of measuring profiles along which the geometrical parameters are constrained. The new workflow is tested using natural and experimentally produced non-cylindrical folds. The geometric parameters obtained can be used to improve our understanding of fold kinematics and fold mechanics and should assist the quantitative analysis of non-cylindrical folds present in gneiss and salt domes and in rocks containing reservoirs of hydrocarbons and minerals deposits.
Morphology of nematic and smectic vesicles
Xing, Xiangjun; Shin, Homin; Bowick, Mark J.; Yao, Zhenwei; Jia, Lin; Li, Min-Hui
2012-01-01
Recent experiments on vesicles formed from block copolymers with liquid-crystalline side chains reveal a rich variety of vesicle morphologies. The additional internal order (“structure”) developed by these self-assembled block copolymer vesicles can lead to significantly deformed vesicles as a result of the delicate interplay between two-dimensional ordering and vesicle shape. The inevitable topological defects in structured vesicles of spherical topology also play an essential role in controlling the final vesicle morphology. Here we develop a minimal theoretical model for the morphology of the membrane structure with internal nematic/smectic order. Using both analytic and numerical approaches, we show that the possible low free energy morphologies include nano-size cylindrical micelles (nano-fibers), faceted tetrahedral vesicles, and ellipsoidal vesicles, as well as cylindrical vesicles. The tetrahedral vesicle is a particularly fascinating example of a faceted liquid-crystalline membrane. Faceted liquid vesicles may lead to the design of supramolecular structures with tetrahedral symmetry and new classes of nano-carriers. PMID:22431595
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 ...
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 ...
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
Labbé-Laurent, M; Tröndle, M; Harnau, L; Dietrich, S
2014-04-07
Recent experiments have demonstrated a fluctuation-induced lateral trapping of spherical colloidal particles immersed in a binary liquid mixture near its critical demixing point and exposed to chemically patterned substrates. Inspired by these experiments, we study this kind of effective interaction, known as the critical Casimir effect, for elongated colloids of cylindrical shape. This adds orientational degrees of freedom. When the colloidal particles are close to a chemically structured substrate, a critical Casimir torque acting on the colloids emerges. We calculate this torque on the basis of the Derjaguin approximation. The range of validity of the latter is assessed via mean-field theory. This assessment shows that the Derjaguin approximation is reliable in experimentally relevant regimes, so that we extend it to Janus particles endowed with opposing adsorption preferences. Our analysis indicates that critical Casimir interactions are capable of achieving well-defined, reversible alignments both of chemically homogeneous and of Janus cylinders.
NASA Astrophysics Data System (ADS)
Cheng, Dajun
1997-01-01
Uniaxial bianisotropic-semiconductor material is a generalization of the well-studied semiconductor material and uniaxial medium. It could be realized by arranging chiral objects in a host semiconductor medium, with a preferred direction. This class of material probably opens up the opportunity to realize artificial intelligence in living organisms. In the present study, based on the concept of characteristic waves and the method of angular spectral expansion, electromagnetic field representations in this class of materials are developed. The analysis indicates that solutions of source-free Maxwell equations for uniaxial bianisotropic-semiconductor material can be represented in sum-integral forms of cylindrical vector wave functions. Addition theorem of vector wave functions for uniaxial bianisotropic-semiconductor material can be straightforwardly derived from that of vector wave functions for isotropic medium. An application of the proposed theory in scattering is presented to show how to use these formulations in a practical way.
Nicols, R.O.
1985-08-15
A 2-D optical analysis is described that allows determination of the intensity distribution on a circular cylinder located in the focal zone of nonperfect concentrators. We call nonperfect concentrators those in which the normal to each differential element of the specular surface departs from its correct position by an angle epsilon, the possible values of which follow a Gaussian distribution of mean value epsilon-bar and standard deviation sigma. The analysis is based on a previous one developed to calculate the intensity distribution at the receiver plane of nonperfect cylindrical concentrators. The analysis permits the consideration of circular receivers displaced from the focus by distance delta/sub f/ in any direction and directions of the incident rays nonparallel to the parabola's symmetry plane. Results for different sets of parameters characterizing the behavior of a given concentrator are shown and compared.
Patients' preferences for information
Kindelan, K.; Kent, G.
1986-01-01
In a study of patients' views of the type of information they would like to receive from the doctor 265 patients from four general practices were given a list of five areas of information — diagnosis, prognosis, treatment, aetiology and social effects of their illness — and asked to rank these in order of importance for that visit. In general, information on diagnosis and prognosis was the most highly valued, while the ways the illness would affect daily activities was the least preferred. Although information on treatment was rarely selected as the first preference it was often the second or third preference. Conversely, diagnosis was the first choice of the largest proportion of patients and the least valued information for 26%. PMID:3440990
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.
Metal Preferences and Metallation*
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
Monolithic Cylindrical Fused Silica Resonators with High Q Factors
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
Novel spherical hohlraum with cylindrical laser entrance holes and shields
NASA Astrophysics Data System (ADS)
Lan, Ke; Zheng, Wudi
2014-09-01
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.
Fast rendering scheme for 3D cylindrical ultrasound data
NASA Astrophysics Data System (ADS)
Choi, Jung Pill; Ra, Jong Beom
2000-04-01
3D ultrasound imaging is an emerging and prospective modality in the ultrasound scanning area. Since 3D ultrasound dat are often acquired by translation or rotation of 2D data acquisition systems, the data can be directly sampled on cylindrical or spherical structured girds rather tan on rectilinear grids. However, visualization of cylindrical or spherical data is more complex than that of rectilinear grids. Therefore, conventional rendering methods resample the grids into rectilinear grids and visualize the resampled rectilinear dat. However, resampling introduces an undesired resolution loss. In this paper a direct rendering scheme of cylindrical ultrasound data is considered. Even though cell sin cylindrical grids have different sizes, they are very similar in shape and contain some regularity. We use this similarity and regularity of cells to reduce rendering time in a projection-based rendering method. To achieve high sped rendering, we prose a simple projection ordering method and a fast projection method using a common edge table. And also, to produce good rendering results, an efficient bilinear interpolation scheme is prosed for the hexahedral projection. In this scheme, since weighting coefficients are calculated in the image plane, we can avoid calculating crossing point sin the object space. Based on the proposed techniques above, we can produce high resolution rendered images directly form a cylindrical 3D ultrasound data set.
Change in electromyographic activity of wrist extensor by cylindrical brace.
Yoon, Jung Joong; Bae, Hasuk
2013-01-01
To verify the effect of a newly-developed cylindrical type forearm brace, which was designed to give focal counterforce perpendicularly on the muscle belly of the wrist extensor. The dominant hands of 24 (12 males, 12 females) healthy subjects were tested. Two types of forearm braces (focal cylindrical type and broad pneumatic type) were examined. The braces were applied at the extensor carpi radialis brevis, 5 to 7 cm distal to the lateral epicondyle. Two surface electrodes were attached to the proximal and distal parts of the brace. By quantitative electromyography, the mean amplitudes of voluntary extensor carpi radialis brevis contraction before and after applying each brace were recorded and analyzed. The mean amplitudes of the focal cylindrical brace and broad pneumatic brace were reduced significantly compared to no brace (p<0.05), with a larger reduction for the cylindrical brace than the pneumatic brace (p<0.05). There was no significant difference between the proximal and distal mean amplitudes with each brace. A cylindrical type brace decreased electromyographic activity in the wrist extensor more effectively than did the pneumatic type brace.
Change in Electromyographic Activity of Wrist Extensor by Cylindrical Brace
Yoon, Jung Joong
2013-01-01
Purpose To verify the effect of a newly-developed cylindrical type forearm brace, which was designed to give focal counterforce perpendicularly on the muscle belly of the wrist extensor. Materials and Methods The dominant hands of 24 (12 males, 12 females) healthy subjects were tested. Two types of forearm braces (focal cylindrical type and broad pneumatic type) were examined. The braces were applied at the extensor carpi radialis brevis, 5 to 7 cm distal to the lateral epicondyle. Two surface electrodes were attached to the proximal and distal parts of the brace. By quantitative electromyography, the mean amplitudes of voluntary extensor carpi radialis brevis contraction before and after applying each brace were recorded and analyzed. Results The mean amplitudes of the focal cylindrical brace and broad pneumatic brace were reduced significantly compared to no brace (p<0.05), with a larger reduction for the cylindrical brace than the pneumatic brace (p<0.05). There was no significant difference between the proximal and distal mean amplitudes with each brace. Conclusion A cylindrical type brace decreased electromyographic activity in the wrist extensor more effectively than did the pneumatic type brace. PMID:23225823
Posatskiy, A O; Chau, T
2012-10-01
Mechanomyography has recently been proposed as a control modality for alternative access technologies for individuals with disabilities. However, MMG recordings are highly susceptible to contamination from limb movements. Pressure-based transducers are touted to be the most robust to external movement although there is some debate about their optimal chamber geometry, in terms of low frequency gain and spectral flatness. To investigate the question of preferred geometry, transducers with cylindrical and conical chambers of varying dimensions were designed, manufactured and tested. Using a computer-controlled electrodynamic shaker, the frequency response of each chamber geometry was empirically derived. Of the cylindrical chambers, the highest gain and the flattest frequency response was exhibited by a chamber 10 mm in diameter and 5-7 mm in height. However, conical chambers offered an average rise in gain of 6.79 ± 1.06 dB/Hz over that achievable with cylindrical geometries. The highest gain and flattest response was achieved with a transducer consisting of a low-frequency MEMS microphone, a 4 μm aluminized mylar membrane and a rigid conical chamber 7 mm in diameter and 5mm in height. This design is recommended for MMG applications where limb movement is prevalent.
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)
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)
Numerical simulation of hydrate formation morphology in cylindrical experimental sand columns
NASA Astrophysics Data System (ADS)
Seol, Y.; Kneafsey, T. J.; Moridis, G. M.
2007-12-01
Using X-ray computed tomography (CT), formation of methane hydrate in columns of moist sand was observed under various conditions of initial water saturation, porosity, pressure, and temperature. Contrary to many studies in porous media that assumed methane hydrate forms uniformly throughout the media, x-ray CT observations of laboratory studies involving hydrate formation showed nonuniform patterns that included circular bands, centered around the core axis, locally concentrations, or uniformly disseminations. Nucleation and accumulation of methane hydrate in porous media can be affected by many factors such as porosity, water saturation, relative permeability, heat conductivity, and inhibiting salts. However, there is no clear explanation on how or why these various patterns of heterogeneous distribution of hydrate formation take place. We conducted numerical simulations using TOUGH+Hydrate to investigate the nonuniform hydrate formation in moist sand, and compared the numerical predictions to the experiment results. The simulations were able to generate the various patterns of hydrate formation and to provide an understanding of the dynamic processes governing the hydrate formation. We conducted sensitivity analyses with respect to the initial water saturation, inhibitor concentration, and porosity, and we evaluated the impact of those parameters on the hydrate formation patterns.
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.
Encoding high-order cylindrically polarized light beams.
Moreno, Ignacio; Davis, Jeffrey A; Cottrell, Don M; Donoso, Ramiro
2014-08-20
In this work we present a setup for the experimental production of cylindrically polarized beams, as well as other variations of polarized light beams. The optical system uses a single transmissive phase-only spatial light modulator, which is used to apply different spatial phase modulation to two output collinear R and L circularly polarized components. Different cylindrically polarized light beams can be obtained by applying different phase shifts to these two circularly polarized components. The system is very efficient since modulation is directly applied to the light beam (as opposed to other common methods operating in the first order of encoded diffraction gratings). Different variations to the cylindrically polarized light beams are also reported, obtained by adding linear or quadratic relative phase shifts between the two circular polarization components of the light beam. Experimental results are provided in all cases.
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.
Determination of thermal diffusivities of cylindrical bodies being cooled
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.
Arbitrarily laminated, anisotropic cylindrical shell under internal pressure
NASA Technical Reports Server (NTRS)
Chaudhuri, Reaz Z.; Balaraman, K.; Kunukkasseril, Vincent X.
1986-01-01
An arbitrarily laminated, anisotropic cylindrical shell of finite length, under uniform internal pressure, is analyzed using Love-Timoshenko's kinematic relations and under the framework of classical lamination theory. The previously obtained solutions for asymmetrically laminated orthotropic (cross-ply) as well as unbalanced-symmetric and balanced-unsymmetric (angle-ply) cylindrical shells under the same loading conditions have been shown to be special cases of the present closed-form solution. Numerical results have been presented for a two-layer cylindrical shell and compared with those obtained using finite element solutions based on the layerwise constant shear-angle theory. These are expected to serve as benchmark solutions for future comparisons and to facilitate the use of unsymmetric lamination in design.
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.
Experimental and numerical analysis of cylindrical straw drying
NASA Astrophysics Data System (ADS)
Goryl, Wojciech; Filipowicz, Mariusz
The paper presents experimental and numerical results of the heat and mass transfer in a cylindrical bale of straw. The experimental measurements were made in a specialized stand of straw driers. Flue gasses, comes from straw combustion in the biomass boiler, are used as a drying medium. There were made measurements of humidity and temperature inside the cylindrical straw bale during the drying process. The results were used to prepare the drying rate curve. Moreover, data were used to validate the numerical model of straw drying. The numerical model was performed to depict the heat and mass transfer inside the straw bale. Furthermore, the model was used to optimize the drying process. The paper presents result of experimental and numerical drying rates of cylindrical straw bale and heat and mass transfer in its interior. As a result of the work numerical model was obtained. It satisfactorily describes the mechanisms inside the drying straw bale.
The cylindrical GEM detector of the KLOE-2 experiment
NASA Astrophysics Data System (ADS)
Bencivenni, G.; Branchini, P.; Ciambrone, P.; Czerwinski, E.; De Lucia, E.; Di Cicco, A.; Domenici, D.; Felici, G.; Fermani, P.; Morello, G.
2017-07-01
The KLOE-2 experiment started its data taking campaign in November 2014 with an upgraded tracking system at the DAΦNE electron-positron collider at the Frascati National Laboratory of INFN. The new tracking device, the Inner Tracker, operated together with the KLOE-2 Drift Chamber, has been installed to improve track and vertex reconstruction capabilities of the experimental apparatus. The Inner Tracker is a cylindrical GEM detector composed of four cylindrical triple-GEM detectors, each provided with an X-V strips-pads stereo readout. Although GEM detectors are already used in high energy physics experiments, this device is considered a frontier detector due to its fully-cylindrical geometry: KLOE-2 is the first experiment benefiting of this novel detector technology. Alignment and calibration of this detector will be presented together with its operating performance and reconstruction capabilities.
Design of elliptic cylindrical thermal cloak with layered structure
NASA Astrophysics Data System (ADS)
Yuan, Xuebo; Lin, Guochang; Wang, Youshan
2017-01-01
Thermal cloak has potential applications in thermal protection and sensing. Based on the theories of spatial transformation and effective medium, layered structure of elliptic cylindrical thermal cloak was designed. According to theoretical analysis and numerical simulation, the layered structure has typical characteristics of perfect thermal cloak. The external temperature field remains unchanged, while the internal temperature gradient decreases obviously. Meanwhile, the cloaking effect is stable in any direction. The cloaking effect can be improved by increasing the number of discretization layers or reducing the cloak thickness. The elliptic cylindrical cloak can be considered as cylindrical cloak when the focal distance is close to zero. This study has provided an effective way for realizing thermal cloak with more complex shapes.
Arbitrarily laminated, anisotropic cylindrical shell under internal pressure
NASA Technical Reports Server (NTRS)
Chaudhuri, Reaz Z.; Balaraman, K.; Kunukkasseril, Vincent X.
1986-01-01
An arbitrarily laminated, anisotropic cylindrical shell of finite length, under uniform internal pressure, is analyzed using Love-Timoshenko's kinematic relations and under the framework of classical lamination theory. The previously obtained solutions for asymmetrically laminated orthotropic (cross-ply) as well as unbalanced-symmetric and balanced-unsymmetric (angle-ply) cylindrical shells under the same loading conditions have been shown to be special cases of the present closed-form solution. Numerical results have been presented for a two-layer cylindrical shell and compared with those obtained using finite element solutions based on the layerwise constant shear-angle theory. These are expected to serve as benchmark solutions for future comparisons and to facilitate the use of unsymmetric lamination in design.
A cylindrical converging shock tube for shock-interface studies.
Luo, Xisheng; Si, Ting; Yang, Jiming; Zhai, Zhigang
2014-01-01
A shock tube facility for generating a cylindrical converging shock wave is developed in this work. Based on the shock dynamics theory, a specific wall profile is designed for the test section of the shock tube to transfer a planar shock into a cylindrical one. The shock front in the converging part obtained from experiment presents a perfect circular shape, which proves the feasibility and reliability of the method. The time variations of the shock strength obtained from numerical simulation, experiment, and theoretical estimation show the desired converging effect in the shock tube test section. Particular emphasis is then placed on the problem of shock-interface interaction induced by cylindrical converging shock waves. For this purpose, membrane-less gas cylinder is adopted to form the interface between two different fluids while the laser sheet technique to visualize the flow field. The result shows that it is convenient to perform such experiments in this facility.
Absolute test for cylindrical surfaces using the conjugate differential method
NASA Astrophysics Data System (ADS)
Huang, Ya; Ma, Jun; Yuan, Caojin; Pruss, Christof; Sun, Weiyuan; Liu, Mincai; Zhu, Rihong; Gao, Zhishan; Osten, Wolfgang
2016-11-01
An absolute testing method for cylindrical surfaces is presented in a null test setup with a computer-generated hologram. The absolute test exploits the symmetry of cylinders, which allows us to introduce a certain shift of the test surface both parallel to and rotated about the centerline while the null test condition is still maintained. With two shifts of the cylindrical surface, four measurements belonging to two groups in conjugate positions can be accomplished to obtain the absolute differential map with the interferometer and null optics errors removed. The absolute surface can be obtained by wavefront reconstruction from local differential data. A simulation of the method is presented to estimate the error propagation. Experimental absolute test results of a concave cylindrical surface with 100-mm radius are given. The measured profiles are compared with those obtained from a commercial profiler, showing a difference of less than 15 nm (root-mean-square).
Modeling oxygen transport in a cylindrical bioartificial pancreas.
Thrash, Marvin
2010-01-01
Encapsulated pancreatic islets in a cylindrical hollow fiber have been reported to reverse diabetes in test animals; however, for many of these animals, the effects have only been temporary. Oxygen deficiency within the fiber has been proposed as a cause of the observed loss of islet viability. A mathematical model of transport and reaction kinetics in a bioartificial pancreas (BAP) has been developed to calculate the oxygen concentration profiles in a cylindrical BAP. Simulation results indicate that hypoxic conditions will exist in large diameter fibers or fibers with islet concentrations >20,000 islets/ml. Moreover, our results show that a significant amount of oxygen is consumed in the tissue region surrounding the cylindrical BAP. Even if the islet survives in a low-oxygen environment, the insulin productivity will likely be reduced.
Bidirectional surface wave splitters excited by a cylindrical wire.
Zhou, Yong Jin; Jiang, Quan; Cui, Tie Jun
2011-03-14
Bidirectional surface wave splitters excited by a cylindrical wire in the microwave frequency have been proposed and fabricated. Compared to the bidirectional subwavelength-slit splitter, the novelty of the proposed structure is the coupling mechanism from the cylindrical wire to the surface gratings. By designing the grating structures with different depths and the feeding wire, electromagnetic waves at the designed frequencies will be confined and guided in the predetermined opposite directions. The finite integral time-domain method is used to model the splitters. Experimental results are presented in the microwave frequencies to verify the new structure, which have very good agreements to the simulated results. Based on the same coupling mechanism, a bidirectional surface wave splitter excited by a cylindrical wire in the terahertz (THz) frequencies is further been proposed and modeled. The simulation results demonstrate the validity of the THz splitter.
Simple model of capillary condensation in cylindrical pores.
Szybisz, Leszek; Urrutia, Ignacio
2002-11-01
A simple model based on an approximation of the dropletlike model is formulated for studying adsorption of fluids into cylindrical pores. This model yields a nearly universal description of capillary condensation transitions for noble gases confined by alkali metals. The system's thermodynamical behavior is predicted from the values of two dimensionless parameters: D* (the reduced asymptotic strength of the fluid-adsorber interaction, a function of temperature) and R* (the reduced radius of the pore). The phenomenon of hysteresis inherently related to capillary condensation is discussed. The connection to a previously proposed universality for cylindrical pores is also established.
Simple model of capillary condensation in cylindrical pores
NASA Astrophysics Data System (ADS)
Szybisz, Leszek; Urrutia, Ignacio
2002-11-01
A simple model based on an approximation of the dropletlike model is formulated for studying adsorption of fluids into cylindrical pores. This model yields a nearly universal description of capillary condensation transitions for noble gases confined by alkali metals. The system's thermodynamical behavior is predicted from the values of two dimensionless parameters: D* (the reduced asymptotic strength of the fluid-adsorber interaction, a function of temperature) and R* (the reduced radius of the pore). The phenomenon of hysteresis inherently related to capillary condensation is discussed. The connection to a previously proposed universality for cylindrical pores is also established.
Non-modal analysis of the diocotron instability: Cylindrical geometry
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.
Microwave guiding in air by a cylindrical filament array waveguide
Chateauneuf, M.; Dubois, J.; Payeur, S.; Kieffer, J.-C.
2008-03-03
Microwave guiding was demonstrated over 16 cm in air using a large diameter hollow plasma waveguide. The waveguide was generated with the 100 TW femtosecond laser system at the Advanced Laser Light Source facility. A deformable mirror was used to spatially shape the intense laser pulses in order to generate hundreds of filaments judiciously distributed in a cylindrical shape, creating a cylindrical plasma wall that acts as a microwave waveguide. The microwaves were confined for about 10 ns, which corresponds to the free electron plasma wall recombination time. The characteristics of the plasma waveguide and the results of microwave guiding are presented.
Real-time wideband cylindrical holographic surveillance system
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.
Real-time wideband cylindrical holographic surveillance system
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.
Broadband sound absorption by lattices of microperforated cylindrical shells
NASA Astrophysics Data System (ADS)
García-Chocano, Victor M.; Cabrera, Suitberto; Sánchez-Dehesa, José
2012-10-01
Absorption of broadband noise by sonic crystals consisting of microperforated cylindrical shells is proposed and experimentally demonstrated. The theoretical study has been performed in the framework of multiple scattering method, where a model for the T matrix of the microperforated shells has been developed. It has been predicted an extraordinary broadband sound absorption that is explained in terms of the multiple scattering phenomena occurring at the surfaces of the absorptive units—the microperforated panels. Our proposal has been supported by experiments performed on a structure consisting of 3 rows of cylindrical shells 3 meters height.
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.
Active Constrained Layer Damping of Thin Cylindrical Shells
NASA Astrophysics Data System (ADS)
RAY, M. C.; OH, J.; BAZ, A.
2001-03-01
The effectiveness of the active constrained layer damping (ACLD) treatments in enhancing the damping characteristics of thin cylindrical shells is presented. A finite element model (FEM) is developed to describe the dynamic interaction between the shells and the ACLD treatments. Experiments are performed to verify the numerical predictions. 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.
Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium
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
The evanescent wavefield part of a cylindrical vector beam
Chen, Rui-Pin; Li, Guoqiang
2013-01-01
The evanescent wave of the cylindrical vector field is analyzed using the vector angular spectrum of the electromagnetic beam. Comparison between the contributions of the TE and TM terms of both the propagating and the evanescent waves associated with the cylindrical vector field in free space is demonstrated. The physical pictures of the evanescent wave and the propagating wave are well illustrated from the vectorial structure, which provides a new approach to manipulating laser beams by choosing the states of polarization in the cross-section of the field. PMID:24104116
Orbital trajectory of an acoustic bubble in a cylindrical resonator.
Desjouy, Cyril; Labelle, Pauline; Gilles, Bruno; Bera, Jean-Christophe; Inserra, Claude
2013-09-01
Acoustic cavitation-induced microbubbles in a cylindrical resonator filled with water tend to concentrate into ring patterns due to the cylindrical geometry of the system. The shape of these ring patterns is directly linked to the Bjerknes force distribution in the resonator. Experimental observations showed that cavitation bubbles located in the vicinity of this ring may exhibit a spiraling behavior around the pressure nodal line. This spiraling phenomenon is numerically studied, the conditions for which a single cavitation bubble follows an orbital trajectory are established, and the influences of the acoustic pressure amplitude and the initial bubble radius are investigated.
Liquid bridge as a tunable-focus cylindrical liquid lens
NASA Astrophysics Data System (ADS)
Chen, H.; Tabatabaei, N.; Amirfazli, A.
2017-01-01
We proposed a method to create a tunable-focus cylindrical liquid lens using a liquid bridge between two narrow surfaces. Due to the surface edge effect, the interface of the liquid bridge (on the long side) was shown to be able to serve as a tunable-focus cylindrical liquid lens. The working distance of the lens can be adjusted by changing either or both of the height of the bridge (H) and the volume of the liquid (V). By varying H and V, the lens can serve as either diverging or converging lens, with a minimum working distance of 2.11 mm.
Ideal cylindrical cloak: perfect but sensitive to tiny perturbations.
Ruan, Zhichao; Yan, Min; Neff, Curtis W; Qiu, Min
2007-09-14
A cylindrical wave expansion method is developed to obtain the scattering field for an ideal two-dimensional cylindrical invisibility cloak. A near-ideal model of the invisibility cloak is set up to solve the boundary problem at the inner boundary of the cloak shell. We confirm that a cloak with the ideal material parameters is a perfect invisibility cloak by systematically studying the change of the scattering coefficients from the near-ideal case to the ideal one. However, because of the slow convergence of the zeroth-order scattering coefficients, a tiny perturbation on the cloak would induce a noticeable field scattering and penetration.
Incorrectness of the usual gyrokinetic treatment in cylindrically symmetric systems
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.
Transverse Vibrations of Hollow Thin-Walled Cylindrical Beams
1953-01-01
REPORT 1129 TRANSVERSE VIBRATIONS OF HOLLOW THIN-WALLED CYLINDRICAL BEAMS By BERNARD 3UDIANSKY and EDWIN T. KRUSZEWSKI Lankly Aetenudea Labsntory...iangey Flew, Va. acea n 4. j ’tifitl Distribution AvailabilitYC04eS I /or fteci0 National Advisory Committee for Aeronautics Hmd piarters, 1714 F Sweet ...fundmenta pr*oWxe ffJlight •[0 REPORT 1129 TRANSVERSE VIBRATIONS OF HOLLOW THIN-WALLED CYLINDRICAL BEAMS’ By BERNARD BuDIANSKY and EDWIN T. Ktuszowiat
Metallurgical Evaluation of the Five-Inch Cylindrical Induction Melter
Imrich, K.J.
2000-08-15
A metallurgical evaluation of the 5-inch cylindrical induction melter (CIM) vessel was performed by the Materials Technology Section to evaluate the metallurgical condition after operating for approximately 375 hours at 1400 to 1500 Degrees Celsius during a 2 year period. Results indicate that wall thinning and significant grain growth occurred in the lower portion of the conical section and the drain tube. No through-wall penetrations were found in the cylindrical and conical sections of the CIM vessel and only one leak site was identified in the drain tube. Failure of the drain tube was associated with a localized over heating and intercrystalline fracture.
Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium.
Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying
2015-06-15
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.
Image effects of cylindrical pipes on continuous beams
Allen, C.K.; Reiser, M.
1996-09-01
We analyze the image effects of a cylindrical pipe on continuous beams with elliptical symmetry. Differential equations involving the second-order spatial moments of a particle distribution are given. From the moment equations, a set of Kapchinskij-Vladimirskij-type equations is developed, which include the image effects of a cylindrical beam pipe. These equations are used to analyze the image effects for focusing, drift, defocusing, drift channels, sheet beams, and a magnetic quadrupole matching section. {copyright} {ital 1996 The American Physical Society.}
The magnetic properties of the hollow cylindrical ideal remanence magnet
NASA Astrophysics Data System (ADS)
Bjørk, R.
2016-10-01
We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived and the generated field is compared to that of a Halbach cylinder of equal dimensions. The ideal remanence magnet is shown in most cases to generate a significantly lower field than the equivalent Halbach cylinder, although the field is generated with higher efficiency. The most efficient Halbach cylinder is shown to generate a field exactly twice as large as the equivalent ideal remanence magnet.
Cylindrical chains of water drops condensing on microstructured lubricant-infused surfaces.
Kajiya, Tadashi; Wooh, Sanghyuk; Lee, Yunchan; Char, Kookheon; Vollmer, Doris; Butt, Hans-Jürgen
2016-11-23
We studied the condensation of water drops on a micro-structured lubricant-infused surfaces. Hierarchical micro-prism surfaces were fabricated by soft imprinting with wet TiO2 nanoparticle paste. After hydrophobization, the patterned surfaces were infused with silicone oil as a lubricant. When cooling at high humidity (over 80%), water drops nucleate and start growing on the surface. Once they have reached a certain size, the drops at neighboring channels of the micro-prisms attract each other and spontaneously form cylindrical chains. These chains of drops align perpendicular to the prism array. The morphology and the length-to-width ratio of the chains of drops depend on the thickness of the lubricant layer. This new concept of water drop alignment on lubricant-infused surfaces offers a new route for pattern formation with condensed drops.
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.
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.
Coaching preferences of athletes.
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.
The Vocational Preference Inventory Scores and Environmental Preferences
ERIC Educational Resources Information Center
Kunce, Joseph T.; Kappes, Bruno Maurice
1976-01-01
This study investigated the relationship between vocational interest measured by the Vocational Preference Inventory (VPI) and preferences of 175 undergraduates for structured or unstructured environments. Males having clear-cut preferences for structured situations had significantly higher Realistic-Conventional scores than those without…
QUASI-PML FOR WAVES IN CYLINDRICAL COORDINATES. (R825225)
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...
Capillary condensation of 4He in cylindrical pores
NASA Astrophysics Data System (ADS)
Urrutia, Ignacio; Szybisz, Leszek
2004-10-01
The adsorption of superfluid 4He confined into cylindrical pores of alkali metals is illustrated by looking at the case of Na. A density functional formalism is utilized for the theoretical description. The energetics and density profiles are determined as a function of the radius of cylinders and the filling fraction. These results are compared with those provided by a simple model recently proposed.
The cylindrical or tubiliform glands of Nephila clavipes.
Candelas, G C; Ortiz, A; Molina, C
1986-02-01
The cylindrical or tubiliform glands of the spider Nephila clavipes have been studied and compared to the large ampullates on which we have previously reported. The three pairs of cylindrical or tubiliform glands secrete the fibroin for the organism's egg case. Their solubilized luminar contents migrate as a homogeneous band in Sodium dodecyl sulfate polyacrylamide gel electrophoresis and turn out to be a larger protein than that produced by the large ampullates. The excised cylindrical glands remain metabolically active for several hours in a simple culture medium, where fibroin synthesis can be monitored through the incorporation of 14C alanine. The glands' response to a fibroin production stimulus does not reach the magnitude displayed by the large ampullates, but this is to be expected since their products supply different functions in this organism. This fibroin also seems to be elongated discontinuously. Translational pauses have been detected in the secretory epithelium of cylindrical and large ampullate glands of Nephila as well as in the silk glands of Bombyx mori. Since these glands produce the fibroin for the females egg case, they should prove to be an interesting model system.
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.
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.
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.
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…
The CEUS automated fiber placement cylindrical manufacturing tool
2015-09-23
MATERIALS ENGINEER LARRY PELHAM OF NASA’S MARSHALL SPACE FLIGHT CENTER IN HUNTSVILLE, ALABAMA, OPERATES THE CEUS AUTOMATED FIBER PLACEMENT CYLINDRICAL MANUFACTURING TOOL IN BUILDING 4707. THE TOOL WILL BE USED BY THE COMPOSITES FOR EXPLORATION UPPER STAGE PROJECT AT MARSHALL, WHICH IS ANALYZING COMPOSITE MATERIALS TO SUPPORT FUTURE HARDWARE FOR NASA’S SPACE LAUNCH SYSTEM AND OTHER NEXT-GENERATION SPACECRAFT…
Simultaneous and Running Impulsive Loading of Cylindrical Shells
1975-06-01
the cylindrical tesi fixture at one of its ends, and the load would run longitiiri-;: nally in the axial direction of the cylinder for those areas...LEAD CYLINDER - TEST 26 DAMAGE "RODUCED BY A SASH LOAD OF 4. S8 KILOTAPS ALMIU CYLINDER- TS :--j2 7~ DAMAG PR DU E BYASS O DOF44 ,LT 12
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.
Two-fluid tearing mode instability in cylindrical geometry
NASA Astrophysics Data System (ADS)
Ito, Atsushi; Ramos, Jesús J.
2017-07-01
This paper investigates the linear stability of a force-free equilibrium in a plasma cylinder of finite aspect ratio, against the two-fluid resistive tearing mode. An analytic dispersion relation is derived by extending to cylindrical geometry the slab geometry boundary layer theory applicable to two-fluid tearing modes for high beta and general ion skin depths [E. Ahedo and J. J. Ramos, Plasma Phys. Controlled Fusion 51, 055018 (2009)]. The cylindrical dispersion relation shows the dependence of the mode growth rate and real frequency on the ion skin depth, through different regimes that range from the single-fluid MHD limit to the electron MHD limit. It also shows that the non-zero real frequency of the mode arises due to the combination of two-fluid and cylindrical effects. A numerical solution of the complete set of normal-mode equations that resolves the fine-scale singular layer is carried out, for a wide range of resistivity and ion skin depth values. The numerically obtained eigenvalues agree very well with the analytic dispersion relation and the agreement improves the smaller the resistivity and the larger the ion skin depth are. Comparison between the numerical eigenfunctions and the inner solutions of the boundary layer theory shows that the eigenfunctions develop imaginary parts within the resonant layer, also due to the combination of two-fluid and cylindrical effects.
On Ideal Stability of Cylindrical Localized Interchange Modes
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.
PCM thermal energy storage in cylindrical containers of various configurations
Mujumdar, A.S.; Ali Ashraf, F.; Menon, A.S.; Weber, M.E.
1981-01-01
Experimental measurements are reported for the time variation of surface-averaged rate of heat storage during melting in single, thin-walled cylindrical containers of copper filled with a commercially available paraffin wax. For the wax used the enthalpy-temperature curve was obtained using a differential scanning calorimeter according to the ASTM method. 12 refs.
QUASI-PML FOR WAVES IN CYLINDRICAL COORDINATES. (R825225)
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...
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.
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.
Calibrated cylindrical Mach probe in a plasma wind tunnel
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.
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…
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.
Theory of precipitation effects on dead cylindrical fuels
Michael A. Fosberg
1972-01-01
Numerical and analytical solutions of the Fickian diffusion equation were used to determine the effects of precipitation on dead cylindrical forest fuels. The analytical solution provided a physical framework. The numerical solutions were then used to refine the analytical solution through a similarity argument. The theoretical solutions predicted realistic rates of...
Strength reliability analysis of stiffened cylindrical shells considering failure correlation
NASA Astrophysics Data System (ADS)
Bai, Xu; Sun, Liping; Qin, Wei; Lv, Yongkun
2014-03-01
The stiffened cylindrical shell is commonly used for the pressure hull of submersibles and the legs of offshore platforms. There are various failure modes because of uncertainty with the structural size and material properties, uncertainty of the calculation model and machining errors. Correlations among failure modes must be considered with the structural reliability of stiffened cylindrical shells. However, the traditional method cannot consider the correlations effectively. The aim of this study is to present a method of reliability analysis for stiffened cylindrical shells which considers the correlations among failure modes. Firstly, the joint failure probability calculation formula of two related failure modes is derived through use of the 2D joint probability density function. Secondly, the full probability formula of the tandem structural system is given with consideration to the correlations among failure modes. At last, the accuracy of the system reliability calculation is verified through use of the Monte Carlo simulation. Result of the analysis shows the failure probability of stiffened cylindrical shells can be gained through adding the failure probability of each mode.
Analysis of cylindrical Langmuir probe using experiment and different theories
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.
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…
Resistive and viscous convection in a cylindrical plasma
Gomberoff, L.
1983-11-01
It is shown that the combined effect of resistivity, viscosity, and thermal conductivity leads to large-scale stationary convection. This is done for a cylindrical current-carrying plasma in a shearless magnetic field. Convection is shown to take place for large wave numbers and B/sub theta//B/sub z/>>1.
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…
Loss Processes of Metastable Molecules in Cylindrical Cavity
NASA Astrophysics Data System (ADS)
Suzuki, Susumu; Itoh, Haruo
2000-10-01
Assuming a closed cylindrical volume, the spatiotemporal variation of the density distribution of the metastable molecules N_2(A^3Σ_u^+) in the cylindrical volume are calculated from the diffusion equation analysis under the different reflection coefficients at the flat electrode surfaces and at the cylindrical wall.(S.Suzuki, H.Itoh, N.Ikuta and H.Sekizawa:Jpn. J. Appl. Phys., 39, 1333, 2000)(S. Suzuki, H. Itoh, H. Sekizawa and N. Ikuta: Papers of Technical Meeting on Electrical Discharges, ED-98-128, 17, 1998 (in Japanese)) We solve the diffusion equation by separation of variables using the boundary condition of the third kind that is taken account of the reflection at the electrode surfaces.(S. Suzuki, H. Itoh, N. Ikuta and H. Sekizawa: J. Phys. D : Appl. Phys., 25, 1568, 1992) The obtained solution of the diffusion equation are possible to describe the density profiles along the longitudinal and the radial directions. The influence of the density distribution by the different reflection coefficient at each of electrodes and at the cylindrical wall is investigated. Furthermore, the effective lifetime of the diffusing metastable molecules is also discussed under different reflection coefficients.
Applications of bent cylindrical mirrors to x-ray beamlines
Heald, S.M.
1981-07-01
Bent cylindrical mirrors are considered as substitutes for paraboloidal and ellipsoidal mirrors in x-ray beamlines. Analytic and raytracing studies are used to compare their optical performance with the corresponding ideal elements. Particular emphasis is placed on obtaining the practical limitations in the application of bent cylinders to typical beamline configurations.
Optical scanning apparatus for indicia imprinted about a cylindrical axis
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.
Wave propagation in laminated orthotropic circular cylindrical shells
NASA Technical Reports Server (NTRS)
Srinivas, S.
1976-01-01
An exact three-dimensional analysis of wave propagation in laminated orthotropic circular cylindrical-shells is developed. Numerical results are presented for three-ply shells, and for various axial wave lengths, circumferential wave numbers, and thicknesses. Results from a thin shell theory and a refined approximate theory are compared with the exact results.
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…
15. CYLINDRICAL FISH SCALER Remnants of the wire screen remain, ...
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
Constitutive sensitivity of the oscillatory behaviour of hyperelastic cylindrical shells
NASA Astrophysics Data System (ADS)
Aranda-Iglesias, D.; Vadillo, G.; Rodríguez-Martínez, J. A.
2015-12-01
Free and forced nonlinear radial oscillations of a thick-walled cylindrical shell are investigated. The shell material is taken to be incompressible and isotropic within the framework of finite nonlinear elasticity. In comparison with previous seminal works dealing with the dynamic behaviour of hyperelastic cylindrical tubes, in this paper we have developed a broader analysis on the constitutive sensitivity of the oscillatory response of the shell. In this regard, our investigation is inspired by the recent works of Bucchi and Hearn (2013) [28,29], who carried out a constitutive sensitivity analysis of similar problem with hyperelastic cylindrical membranes subjected to static inflation. In the present paper we consider two different Helmholtz free-energy functions to describe the material behaviour: Mooney-Rivlin and Yeoh constitutive models. We carry out a systematic comparison of the results obtained by application of both constitutive models, paying specific attention to the critical initial and loading conditions which preclude the oscillatory response of the cylindrical tube. It has been found that these critical conditions are strongly dependent on the specific constitutive model selected, even though both Helmholtz free-energy functions were calibrated using the same experimental data.
Thermal runaway and microwave heating in thin cylindrical domains
NASA Astrophysics Data System (ADS)
Ward, Michael J.
2002-04-01
The behaviour of the solution to two nonlinear heating problems in a thin cylinder of revolution of variable cross-sectional area is analysed using asymptotic and numerical methods. The first problem is to calculate the fold point, corresponding to the onset of thermal runaway, for a steady-state nonlinear elliptic equation that arises in combustion theory. In the limit of thin cylindrical domains, it is shown that the onset of thermal runaway can be delayed when a circular cylindrical domain is perturbed into a dumbell shape. Numerical values for the fold point for different domain shapes are obtained asymptotically and numerically. The second problem that is analysed is a nonlinear parabolic equation modelling the microwave heating of a ceramic cylinder by a known electric field. The basic model in a thin circular cylindrical domain was analysed in Booty & Kriegsmann (Meth. Appl. Anal. 4 (1994) p. 403). Their analysis is extended to treat thin cylindrical domains of variable cross-section. It is shown that the steady-state and dynamic behaviours of localized regions of high temperature, called hot-spots, depend on a competition between the maxima of the electric field and the maximum deformation of the circular cylinder. For a dumbell-shaped region it is shown that two disconnected hot-spot regions can occur. Depending on the parameters in the model, these regions, ultimately, either merge as time increases or else remain as disconnected regions for all time.
Cylindrical Millemeter-Wave Imaging Technique and Applications
Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.
2006-08-01
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 measurements 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 is 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.
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 %.
Spherical coordinate descriptions of cylindrical and spherical Bessel beams.
Poletti, M A
2017-03-01
This paper derives a generalized spherical harmonic description of Bessel beams. The spherical harmonic description of the well-known cylindrical Bessel beams is reviewed and a family of spherical Bessel beams are introduced which can provide a number of azimuthal phase variations for a single beam radial amplitude. The results are verified by numerical simulations.
Simulated, Theoretical and Experimental Shock Trajectories in Cylindrical Geometry
NASA Astrophysics Data System (ADS)
Kanzleiter, Randall; Atchison, Walter; Bowers, Richard; Guzik, Joyce
2001-06-01
The current work compares computations and similarity relations for convergent shocks with experimental data from cylindrical implosions on the Shiva Star capacitor bank at AFRL. These experiments consisted of a solid cylindrical aluminum liner that is magnetically imploded onto a central target. The central target consists of an inner Lucite cylinder surrounded by an outer Sn layer. Shock propagation within the Lucite is measured to provide comparisons between simulations and theory of convergent shocks. Target design utilized the adaptive mesh refinement (AMR) Eulerian hydrodynamics code RAGE in 2- and 3D. 1D models of the solid liner utilizing the RAVEN MHD code set initial liner/target interaction parameters, which are then used as initial conditions for the RAGE calculations. At liner/target impact, a convergent shock is generated that drives subsequent hydrodynamics experiments. In concentric targets, shocks will converge on axis, characterizing the symmetry of the liner driver. By shifting the Lucite target center away from the liner symmetry axis, variations in shock propagation velocity generate off-center shock convergence. Comparison of experimentally measured and simulated shock trajectories will be discussed as will convergence effects associated with cylindrical geometry. Efforts are currently underway to compare equation-of-state effects by utilizing a Gruneisen EOS instead of the original SESAME tables. Radial convergence is examined through comparisons with similarity solutions in cylindrical geometry.
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.
Development of chemically vapor deposited rhenium emitters of (0001) preferred crystal orientation
NASA Technical Reports Server (NTRS)
Yang, L.; Hudson, R. G.
1973-01-01
Rhenium thermionic emitters were prepared by the pyrolysis of rhenium chlorides formed by the chlorination of rhenium pellets. The impurity contents, microstructures, degrees of (0001) preferred crystal orientation, and vacuum electron work functions of these emitters were determined as a function of deposition parameters, such as substrate temperature, rhenium pellet temperature and chlorine flow rate. A correlation between vacuum electron work function and degree of (0001) preferred crystal orientation was established. Conditions for depositing porosity-free rhenium emitters of high vacuum electron work functions were defined. Finally, three cylindrical rhenium emitters were prepared under the optimum deposition conditions.
Female Career Preference and Androgyny.
ERIC Educational Resources Information Center
Clarey, Joanne H.; Sanford, Alpheus
1982-01-01
Investigated the traditional or nontraditional orientation of the career preferences of androgynous and traditional females (N=62). Administered the Bem Sex Role Inventory and a career preference scale. Results indicated that androgynous females explore wider ranges of occupational choices. (RC)
Cylindrical dielectric elastomer actuators reinforced with inextensible fibers
NASA Astrophysics Data System (ADS)
Goulbourne, Nakhiah C. S.
2006-03-01
Novel actuator configurations for various applications can be obtained using cylindrical dielectric elastomer actuators. A new configuration for a contractile electro-elastomer is presented here for the first time. A cylindrical or tubular configuration is used to realize simultaneous axial shortening and radial expansion when a voltage is applied across the thickness of the hollow cylinder. In this configuration, the inner and outer surfaces of a cylindrical dielectric elastomer are coated with compliant electrodes. The outer cylindrical surface is then enclosed by a network of helical fibers that are very thin, very flexible and inextensible. Fiber networks or cord families are commonly used in many different materials and for a variety of applications. The primary purpose of these networks is structural, that is to say, for reinforcement. The composite active structure proposed here is reminiscent of the McKibben actuator, a pneumatically actuated cylindrical construct consisting of a flexible rubber bladder sheathed in a fiber network, which garners its impressive contracting force from the inextensible fibers that prevent axial extension when an inflation pressure is applied to the internal bladder [1]. The system is modeled using an electro- elastic formulation derived from the large deformation theory of reinforced cylinders [2]. The model combines Maxwell-Faraday electrostatics and nonlinear elasticity theory [3]. Illustratively, solutions are obtained assuming a Mooney-Rivlin material model for a silicone actuator. The results indicate that the relationship between the axial contraction force and the axial shortening is linear for the voltage range considered. The importance of other system parameters such as the fiber angle and the applied constant pressure is also reported.
Therapeutic Recreation Majors' Work Preference.
ERIC Educational Resources Information Center
Barber, Elizabeth H.; Magafas, Anita
1992-01-01
Investigates the client age/disability work preference of 76 therapeutic recreation undergraduate students at 3 universities. Results indicate a preference to work with younger clients, disability groups, and physically impaired clients. Chronically ill clients were last in work preference. Students need exposure to the benefits of working with…
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)
Shaping of parabolic cylindrical membrane reflectors for the DART precision test bed
NASA Technical Reports Server (NTRS)
White, C.; Salama, M.; Dragovan, M.; Schroeder, J.; Barber, D.; Dooley, J.
2003-01-01
The DART is a new telescope architecture consisting of two cylindrical parabolic reflectors. The system is ideally suited to using tensioned membranes for the reflective surfaces, owing to the zero Gaussian curvature of a cylindrical parabola.
Morphological Consequences of Frustration in ABC Triblock Polymers
Radlauer, Madalyn R.; Sinturel, Christophe; Asai, Yusuke; Arora, Akash; Bates, Frank S.; Dorfman, Kevin D.; Hillmyer, Marc A.
2016-12-19
Three poly(styrene)-block-poly(isoprene)-block-poly(lactide) (PS-b-PI-b-PLA, SIL) triblock terpolymers were synthesized and characterized in the bulk and as thin films. The pronounced incompatibility of the covalently connected PI and PLA led to significant frustration and the tendency to minimize their intermaterial dividing surface area. This resulted in the formation of a core–shell cylinder morphology with exaggerated nonconstant mean curvature from triblock polymers with equal block volume fractions rather than the more typical lamellar morphology. The effect of frustration was magnified in thin films by both confinement and interfacial interactions such that the PI domains became discontinuous. Self-consistent field theory (SCFT) calculations emphasize that the marked difference in the PS/PI and PI/PLA interaction parameters promotes the formation of nonlamellar morphologies. However, SCFT predicts that lamellar morphology is more stable than the observed cylindrical morphology, demonstrating a limitation that arises from the underlying assumptions.
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…
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…
Collective preferences in strategic decisions.
Rose, Jo; Colman, Andrew M
2007-12-01
In the theories of team reasoning of Sugden and Bacharach, players are assumed to be motivated in some circumstances to maximize collective rather than individual utilities. An experiment was performed to assess whether preferences underlying such collective payoff maximization occur. An opportunistic sample of 50 undergraduate and graduate students, 7 men and 43 women ages 19 to 42 years (M= 23.0, SD=5.4), expressed preferences among the outcomes of strategic decisions presented in vignettes designed to engage social value orientations of individualism, altruism, competitiveness, equality seeking, or collective preferences. In the vignettes designed to engage collective preferences, and significantly less frequently in the other vignettes, preferences were biased toward outcomes maximizing collective payoffs, and respondents invariably gave team-reasoning explanations for their preferences. These results provide evidence for collective preferences according to theories of team reasoning and empirical support for one of the essential assumptions of these theories.
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.
Stable plasma configurations in a cylindrical magnetron discharge
Levchenko, I.; Romanov, M.; Keidar, M.; Beilis, I. I.
2004-09-20
Transition between different plasma configurations is studied in a system with negative biased cylindrical target in crossed ExB fields. It was found that the diffuse plasma torus formed around the cylindrical target in relatively small magnetic field (0.02 T on target surface) changes the shape with magnetic field to form a thin disk with a width lower than 1 cm when target voltage is less than -400 V. The target current decreases sharply when the magnetic field reaches some critical value. When the target voltage exceeds 400 V, the target current increases with the magnetic field and the plasma has always toroidal shape. The plasma behavior can be understood taking in account the interaction of the drift currents and the magnetic field.
Cylindrical luminescent solar concentrators with near-infrared quantum dots.
Inman, R H; Shcherbatyuk, G V; Medvedko, D; Gopinathan, A; Ghosh, S
2011-11-21
We investigate the performance of cylindrical luminescent solar concentrators (CLSCs) with near-infrared lead sulfide quantum dots (QDs) in the active region. We fabricate solid and hollow cylinders from a composite of QDs in polymethylmethacrylate, prepared by radical polymerization, and characterize sample homogeneity and optical properties using spectroscopic techniques. We additionally measure photo-stability and photocurrent outputs under both laboratory and external ambient conditions. The experimental results are in good agreement with theoretical calculations which demonstrate that the hollow CLSCs have higher absorption of incident radiation and lower self-absorption compared to solid cylindrical and planar geometries with similar geometric factors, resulting in a higher optical efficiency. © 2011 Optical Society of America
Nonlinear dynamo action in a cylindrical container driven by precession
NASA Astrophysics Data System (ADS)
Nore, C.; Léorat, J.; Guermond, J.-L.; Luddens, F.
2011-12-01
Precession, which results simply from the composition of two rotations with distinct axes, is an efficient way to drive a 3D flow in a closed rigid container. Are such flows relevant to dynamo action in some astrophysical bodies? Positive answers are available for a spherical and a spheroidal containers, using parameters which are, however, not realistic. An experimental approach could be relevant to natural dynamos and seems within reach using a cylindrical container (cf. the experiment now planned at the DREsden Sodium facility for DYNamo and thermohydraulic studies in Germany (DRESDYN), F. Stefani, personal communication, 2011). Using a nonlinear magnetohydrodynamics (MHD) code (SFEMaNS), we numerically demonstrate that precession is able to drive a cylindrical dynamo.
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.
Optimization of direct drive irradiation uniformity of cylindrical target
NASA Astrophysics Data System (ADS)
Tian, Chao; Shan, Lianqiang; Zhou, Weimin; Liu, Dongxiao; Bi, Bi; Zhang, Feng; Wang, Weiwu; Yuan, Zongqiang; Yang, Lei; Gu, Yuqiu; Zhang, Baohan
2017-07-01
The irradiation uniformity of a cylindrical target directly driven by laser beams has been considered, which is relevant for fast ignition electron-transport experiments. The laser intensity distribution on the cylindrical target surface is analyzed and optimized by applying the polar direct drive technique and adjusting the laser beam parameters. Moreover, the rotation of laser spot around its propagation axis is taken into consideration. A case study based on the SG-III prototype laser configuration is presented to demonstrate the optimization approach. The irradiation uniformity is reduced from 10% to 1.6% for perfectly balanced beams, and the effects of uncertainties in beam errors (power imbalance and pointing error) are also studied. Furthermore, differences in laser absorption with different incident angles are taken into account and the results show that highly uniform energy deposition can be achieved.
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.
Single-file diffusion of protein drugs through cylindrical nanochannels.
Yang, Seung Yun; Yang, Jeong-A; Kim, Eung-Sam; Jeon, Gumhye; Oh, Eun Ju; Choi, Kwan Yong; Hahn, Sei Kwang; Kim, Jin Kon
2010-07-27
A new drug delivery device using cylindrical block copolymer nanochannels was successfully developed for controlled protein drug delivery applications. Depending on the hydrodynamic diameter of the protein drugs, the pore size in cylindrical nanochannels could be controlled precisely down to 6 nm by Au deposition. Zero-order release of bovine serum albumin (BSA) and human growth hormone (hGH) by single-file diffusion, which has been observed for gas diffusion through zeolite pores, was realized up to 2 months without protein denaturation. Furthermore, a nearly constant in vivo release of hGH from the drug delivery nanodevice implanted to Sprague-Dawley (SD) rats was continued up to 3 weeks, demonstrating the feasibility for long-term controlled delivery of therapeutic protein drugs.
Coupled domain wall oscillations in magnetic cylindrical nanowires
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.
Air-coupled ultrasonic investigation of stacked cylindrical rods.
Liu, Jingfei; Declercq, Nico F
2012-06-01
Measurement of the periodicities of diffraction gratings composed of stacked cylindrical rods is explored using an air-coupled ultrasonic technique. Acoustic Bragg scattering from three periodic structures is investigated by means of a polar scan. Consequently, Bragg angles and corresponding frequencies are obtained from angular spectrograms, using two different data acquisition approaches. According to the principle of Bragg scattering, the periodicities of the three periodic structures, which are equal to the diameter of the cylindrical rods, are determined. In order to evaluate the reliability of the technique and its accuracy, the obtained diameters are compared with those directly measured with a digital caliber. To show the robustness of the technique measurements are done with transducers of different quality.
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.
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.
An unnoticed property of the cylindrical relativistic Brillouin flow
NASA Astrophysics Data System (ADS)
Simon, D. H.; Lau, Y. Y.; Luginsland, J. W.; Gilgenbach, R. M.
2012-04-01
It is shown that the vector potential and the scalar potential satisfy a Buneman-Hartree like (BHL) condition and a Hull-cutoff like (HCL) condition everywhere within the Brillouin flow of a cylindrical, relativistic magnetron, when the phase velocity in the Buneman-Hartree condition is replaced by the laminar, local flow velocity of the Brillouin flow. The vector potential and the scalar potentials include the Brillouin flow's self magnetic field and the self electric fields. The HCL condition reduces to the conventional Hull cutoff condition derived from single particle orbit theory when the Brillouin hub extends to the anode. However, the BHL condition reduces to the conventional Buneman-Hartree condition only in the planar magnetron limit but may be substantially different for a cylindrical magnetron, as demonstrated recently [Lau et al., Phys. Plasmas 17, 033102 (2010)]. These conclusions apply also to the inverted magnetron configuration. The effects of ions are discussed.
Precession of cylindrical dust particles in the plasma sheath
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.
Enhanced converse magnetoelectric effect in cylindrical piezoelectric-magnetostrictive composites
NASA Astrophysics Data System (ADS)
Wu, Gaojian; Zhang, Ru; Zhang, Ning
2016-10-01
Enhanced converse magnetoelectric (ME) effect has been experimentally observed in cylindrical PZT-Terfenol-D piezoelectric-magnetostrictive bilayered composites, where the piezoelectric and magnetostrictive components are coupled through normal stresses instead of shear stresses that act in most of previous multiferroic composites. A theoretical model based on elastodynamics analysis has been proposed to describe the frequency response of converse ME effect for axial and radial modes in the bilayered cylindrical composites. The theory shows good agreement with the experimental results. The different variation tendency of resonant converse ME coefficient, as well as different variation rate of resonance frequency with bias magnetic field for axial and radial modes is interpreted in terms of demagnetizing effect. This work is of theoretical and technological significance for the application of converse ME effect as magnetic sensor, transducers, coil-free flux switch, etc.
Fem Formulation of Heat Transfer in Cylindrical Porous Medium
NASA Astrophysics Data System (ADS)
Azeem; Khaleed, H. M. T.; Soudagar, Manzoor Elahi M.
2017-08-01
Heat transfer in porous medium can be derived from the fundamental laws of flow in porous region ass given by Henry Darcy. The fluid flow and energy transport inside the porous medium can be described with the help of momentum and energy equations. The heat transfer in cylindrical porous medium differs from its counterpart in radial and axial coordinates. The present work is focused to discuss the finite element formulation of heat transfer in cylindrical porous medium. The basic partial differential equations are derived using Darcy law which is the converted into a set of algebraic equations with the help of finite element method. The resulting equations are solved by matrix method for two solution variables involved in the coupled equations.
Optimization of the Performance of Cylindrical Hall Thrusters
NASA Astrophysics Data System (ADS)
Smirnov, Artem; Raitses, Yevgeny; Fisch, Nathaniel J.
2006-10-01
Cylindrical Hall thrusters have lower surface-to-volume ratio than conventional (annular) design Hall thrusters and, thus, seem to be more promising for scaling down. We present the results of the performance study of the cylindrical Hall thrusters with channel outer diameters of 2.6 cm and 3 cm. The effect of the magnetic field distribution and segmented electrodes on the thruster discharge characteristics and efficiency is investigated. The experimental results demonstrate a substantial flexibility in the thruster magnetic field configuration, which is a key tool in achieving the high-efficiency operation. The electron confinement and ion acceleration can be optimized over a family of realizable magnetic field distributions. Y. Raitses and N.J. Fisch, Phys. Plasmas 8, 2579 (2001). Artem Smirnov, invited talk, this conference.
Resonance in a cylindrical wraparound microstrip structure with superstrate
NASA Astrophysics Data System (ADS)
Wong, Kin-Lu; Tsai, Ruenn-Bo; Row, Jeen-Sheen
1994-06-01
Analysis of the resonance problem of a cylindrical wrap-around microstrip structure with superstrate is presented. In this study the rigorous full-wave formulation and Galerkin's method are used. The numerical convergence for the selected sinusoidal basis functions with edge singularity is also discussed. Numerical results of the superstrate loading effects on the real and imaginary parts of complex resonant frequency of the structures as a radiator and as a resonator are calculated and analyzed.
Liquid-drop-like model for cylindrical helium systems
NASA Astrophysics Data System (ADS)
Szybisz, Leszek
2000-08-01
Free liquid 4He at T=0 K with cylindrical symmetry is studied. The ground-state energy and chemical potential are computed by using a density functional approach. A liquid-drop-like model is formulated for analyzing the behavior of these observables as a function of the size of the systems. It is shown that such a model allows to get precise information about the asymptotic values of the energy per particle and surface tension.
Transition in Electron Transport in a Cylindrical Hall Thruster
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.
A tool for installation and removal of cylindrical baffles
NASA Technical Reports Server (NTRS)
Pessin, R.
1980-01-01
Simple tool based on principle of automobile oil wrench slips over cylindrical thread-on baffle to install or remove it from baffle assembly. Tool consists of curled metal sheet brazed onto handgrip. Handgrip is adapted to be driven by wrench, ratchet, extension, torque wrench, or some other convenient tool. Clockwise twist of handgrip, tightens metal sheet around baffle to advance it into threaded joint. Counterclockwise twist loosens sheet for repositioning or tool removal.
Evolution of bulk strain solitons in cylindrical inhomogeneous shells
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.
Analysis of cylindrical arrays of microstrip rectangular patches
NASA Astrophysics Data System (ADS)
da Silva, C. M.; Lumini, F.; Lacava, J. C. D.; Richards, F. P.
1991-04-01
A model for analysis of the radiation characteristics of cylindrical arrays of microstrip rectangular patches is presented. The model is based on the Green function for the multilayered structure calculated in the Fourier domain. The fields radiated by the array are calculated through an asymptotic expression obtained by the application of the stationary phase method. Radiation characteristics such as the directivity function, the ripple and the crosspolarization level are discussed for arrays excited in the TM(01) mode.
Theory of semicollisional drift-interchange modes in cylindrical plasmas
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.
Evaluation of direct-exchange areas for a cylindrical enclosure
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.
The geometric factor of a cylindrical plate electrostatic analyzer
NASA Technical Reports Server (NTRS)
Johnstone, A. D.
1971-01-01
A method for calculating the geometric factor of cylindrical plate electrostatic energy analyzers with various detector geometries is described. The effects of the fringe-field are estimated. For a special simple case an exact geometric factor is calculated enabling an estimate of the inaccuracies of the approximations used in other cases. The results of some calculations are presented and a simple approximate expression for the geometric factor is deduced.
The geometric factor of a cylindrical plate electrostatic analyzer.
NASA Technical Reports Server (NTRS)
Johnstone, A. D.
1972-01-01
A method for calculating the geometric factor of cylindrical plate electrostatic energy analyzers with various detector geometries is described. The effects of the fringe field are estimated. For a special simple case an exact geometric factor is calculated, enabling an estimate to be made of the inaccuracies of the approximations used in other cases. The results of some calculations are presented, and a simple approximate expression for the geometric factor is deduced.
Characteristic impedances in output cylindrical coaxial cavity resonator of klystron
Dong, Yuhe; Xie, Xingjuan; Huang, Chuanlu
2011-07-01
Cylindrical coaxial cavity resonator with shift-tubes coupled with rectangular waveguide is designed. The gap characteristic impedance and external quality factor of higher order transverse magnetic mode TM{sub 310} in the cavity are simulated with high frequency electromagnetic simulator ISFEL-3D. The ununiformity of the characteristic impedance resulted from the coupling aperture is reduced through introduction of concave delves on peripheral wall of the cavity. (author)
Development of cylindrical secondary lithium/polyaniline batteries
NASA Astrophysics Data System (ADS)
Changzhi, Li; Borong, Zhang; Baochen, Wang
1993-04-01
The cylindrical 'D'-size batteries were fabricated by polyaniline paste cathode and lithium foil anode sandwiched with microporous polypropylene separator. The electrolyte used was LiClO 4 dissolved in a mixed solvent of propylene carbonate and dimethoxyethane. The results of charge/discharge curves, charge/discharge cycles, the short-circuit current, the open-circuit voltage storage and the change of discharge capacity with temperature, discharge current are reported.
Operating Characteristics of Cylindrical and Annular Helicon Sources (Preprint)
2007-09-22
2007 IEPC), Florence Italy, 17-20 Sep 2007. IEPC-2007-71. 14. ABSTRACT The power required to create an ionized plasma is a significant energy...strengths up to 1.6 kG for both cylindrical and annular configurations. Measurements of the resultant plasma load impedance have revealed distinct...an ionized plasma is a significant energy loss mechanism in typical electric propulsion systems. The use of wave-driven helicon sources is one
Cylindrical Panel Interior Noise Control Using a Pair of Piezoelectric Actuator and Sensor
NASA Astrophysics Data System (ADS)
LIN, O. R.; LIU, Z.-X.; WANG, Z.-L.
2001-09-01
Active control of acoustic pressure in a cylindrical cavity with a flexible cylindrical panel using a pair of piezoelectric actuator and sensor, which is one part of the cylindrical panel, is simulated. Model expansion method is used in the establishment of the state equation of the system. The active vibration control of the cylindrical panel and the interior noise reduction are performed by applying the linear quadratic Gaussian (LQG) control theory to the structural acoustic coupled system. Two cases of different external forces acting on the cylindrical panel are illustrated. The results demonstrate that such a control system can efficiently reduce the structural-borne noise.
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.
Operational characteristics and plasma measurements in cylindrical Hall thrusters
NASA Astrophysics Data System (ADS)
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.
Method for fabrication of cylindrical microlenses of selected shape
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.
Rayleigh-Taylor instability experiments in a cylindrically convergent geometry
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.
Chain-Based Communication in Cylindrical Underwater Wireless Sensor Networks
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
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.
THE ATHENA ASTROPHYSICAL MAGNETOHYDRODYNAMICS CODE IN CYLINDRICAL GEOMETRY
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.
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.
Characteristics of Cylindrical Microwave Plasma Source at Low Pressure
NASA Astrophysics Data System (ADS)
Park, Seungil; Youn, S.; Kim, S. B.; Yoo, S. J.
2016-10-01
A microwave plasma source with a cylindrical resonance cavity has been proposed to generate the plasma at low pressure. This plasma source consists of magnetron, waveguide, antenna, and cavity. The microwave generating device is a commercial magnetron with 1 kW output power at the frequency of 2.45 GHz. The microwave is transmitted through the rectangular waveguide with the whistle shape, and coupled to the cavity by the slot antenna. The resonant mode of the cylindrical cavity is the TE111 mode. The operating pressure is between 0.1 Torr and 0.3 Torr with the Argon and nitrogen gas. The electron temperature and electron number density of argon plasma were measured with the optical emission spectroscopy measurement. And Ar1s5 metastable density was measured using tunable diode laser absorption spectroscopy (TDLAS). The plasma diagnostic results of a cylindrical microwave plasma source would be described in this study. This work was supported by R&D Program of ``Plasma Advanced Technology for Agriculture and Food (Plasma Farming)'' through the National Fusion Research Institute of Korea (NFRI) funded by the Government funds.
Chain-based communication in cylindrical underwater wireless sensor networks.
Javaid, Nadeem; Jafri, Mohsin Raza; Khan, Zahoor Ali; Alrajeh, Nabil; Imran, Muhammad; Vasilakos, Athanasios
2015-02-04
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.
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.
Method for fabrication of cylindrical microlenses of selected shape
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.
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.
Method for fabrication of cylindrical microlenses of selected shape
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.
Experimental and numerical investigation of cylindrical and hemispherical jet formation
NASA Astrophysics Data System (ADS)
Betney, Matthew; Foster, Peta; Ringrose, Tim; Edwards, Thomas; Tully, Brett; Doyle, Hugo; Hawker, Nicholas; First Light Fusion Ltd. Team
2016-11-01
This paper presents a detailed investigation of the formation of jets in cylindrical and spherical cavities, when impacted by shocks at extreme pressures. As the shock pressure increases the effects of material strength lessen in proportion. Beyond a certain magnitude the behaviour is referred to as "hydrodynamic". In this domain both cylindrical and spherical cavities involute to form jets, which go on to strike the leeward cavity wall, compressing the cavity contents to high pressures and temperatures. In this study, the jet formation process is isolated by cutting hemispherical and half-cylindrical cavities from the rear side of PMMA and copper blocks. This allows direct measurement of the jet speed and shape using high speed imaging, providing data against which numerical models may be compared. Shock waves at pressures of up to 30 GPa are formed in the targets by the impact of projectiles from a two-stage light gas gun, at velocities of up to 7 km/s. Numerically, the jet formation process is modelled using our in-house front-tracking code. This code uses Lagrangian hypersurfaces to model the interfaces between different media, with an underlying Eulerian mesh used to model the bulk flow. Detailed comparisons between numerical and experimental results are presented.
Macrophage uptake of cylindrical microparticles investigated with correlative microscopy.
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. Copyright © 2015 Elsevier B.V. All rights reserved.
A mathematical model of microalgae growth in cylindrical photobioreactor
NASA Astrophysics Data System (ADS)
Bakeri, Noorhadila Mohd; Jamaian, Siti Suhana
2017-08-01
Microalgae are unicellular organisms, which exist individually or in chains or groups but can be utilized in many applications. Researchers have done various efforts in order to increase the growth rate of microalgae. Microalgae have a potential as an effective tool for wastewater treatment, besides as a replacement for natural fuel such as coal and biodiesel. The growth of microalgae can be estimated by using Geider model, which this model is based on photosynthesis irradiance curve (PI-curve) and focused on flat panel photobioreactor. Therefore, in this study a mathematical model for microalgae growth in cylindrical photobioreactor is proposed based on the Geider model. The light irradiance is the crucial part that affects the growth rate of microalgae. The absorbed photon flux will be determined by calculating the average light irradiance in a cylindrical system illuminated by unidirectional parallel flux and considering the cylinder as a collection of differential parallelepipeds. Results from this study showed that the specific growth rate of microalgae increases until the constant level is achieved. Therefore, the proposed mathematical model can be used to estimate the rate of microalgae growth in cylindrical photobioreactor.
Cylindrical Effects on Magneto-Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
Weis, Matthew; Lau, Yue Ying; Gilgenbach, Ronald; Jennings, Christopher; Hess, Mark
2012-10-01
This paper concentrates on the effects of cylindrical geometry on the magneto-Rayleigh-Taylor instability (MRT), a major concern in the magnetized liner inertial fusion concept (MagLIF) [1]. Several issues are being studied, such as the Bell-Plesset effect [2], the effects of magnetic shear and feedthrough [3], and the nonzero MRT growth rate that remains (but was hardly noticed) in the k = m = 0 limit in Harris' seminal paper on a cylindrical liner [4], where k and m are respectively the azimuthal and axial wavenumber. We shall use simulation and direct integration of the eigenvalue equation to investigate the importance of the cylindrical geometry, which is particularly relevant in the final stage of compression in the MagLIF concept. [4pt] [1] S. A. Slutz, et. al, Phys. Plasmas 17, 056303 (2010). [0pt] [2] G. I. Bell, Los Alamos Scientific Laboratory, Report LA-1321 (1951); M. S. Plesset, J. Appl. Phys. 25, 96 (1954).[0pt] [3] P. Zhang et al., Phys. Plasmas 19, 200703 (2012); Y. Y. Lau et al., Phys. Rev. E 83, 006405 (2011). [0pt] [4] E. G. Harris, Phys. Fluids 5, 1057 (1962).
Microfluidic step-emulsification in a cylindrical geometry
NASA Astrophysics Data System (ADS)
Chakraborty, Indrajit; Leshansky, Alexander M.
2016-11-01
The model microfluidic device for high-throughput droplet generation in a confined cylindrical geometry is investigated numerically. The device comprises of core-annular pressure-driven flow of two immiscible viscous liquids through a cylindrical capillary connected co-axially to a tube of a larger diameter through a sudden expansion, mimicking the microfluidic step-emulsifier (1). To study this problem, the numerical simulations of axisymmetric Navier-Stokes equations have been carried out using an interface capturing procedure based on coupled level set and volume-of-fluid (CLSVOF) methods. The accuracy of the numerical method was favorably tested vs. the predictions of the linear stability analysis of core-annular two-phase flow in a cylindrical capillary. Three distinct flow regimes can be identified: the dripping (D) instability near the entrance to the capillary, the step- (S) and the balloon- (B) emulsification at the step-like expansion. Based on the simulation results we present the phase diagram quantifying transitions between various regimes in plane of the capillary number and the flow-rate ratio. MICROFLUSA EU H2020 project.
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.
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.
NASA Astrophysics Data System (ADS)
Hao, Xiuqing; Wang, Li; Lv, Danhui; Wang, Quandai; Li, Liang; He, Ning; Lu, Bingheng
2015-01-01
Recently, the construction of stable superhydrophobicity on metallic wetting surfaces has gained increasing attention due to its potential wide applications. In this paper, we propose an economic fabricating method, which not only is suitable for metallic planar surfaces, but also could be applied onto cylindrical inner surfaces. It mainly involves two steps: etching micro-concaves by a movable mask electrochemical micromachining (EMM) technique and fabricating nanopillars of ZnO by a hydrothermal method. Then the influences of surface morphology on the static and dynamic behaviors of water droplets are investigated. The energy loss during impact on the surfaces is quantified in terms of the restitution coefficient for droplets bouncing off the surfaces. For hierarchical structures with excellent superhydrophobicity (contact angle ≈180° and sliding angle ≤1°), the droplet bounces off the surface several times, superior to the droplet's response on single nanopillars (contact angle ≈165.8° and sliding angle ≈6.29°) where droplet bounces off only for limited a number of times, and even far better than the dynamics of a liquid droplet impinging on microstructures (contact angle ≈132.1° and sliding angle >90°) where droplet does not rebound and remains pinned. The highest elasticity is obtained on the hierarchical surface, where the restitution coefficient can be as large as 0.94. The fabricating method is then applied onto the cylindrical inner surface and the wetting behavior is confirmed to be consistent with the planar surface. This method, which can be generalized to any kind of solid electroconductive metal or other surfaces with different shapes, could find wide practical applications in self-cleaning surfaces, chemical industry, microfluidic devices, mechanical engineering and aviation.
Sub-aperture stitching test of a cylindrical mirror with large aperture
NASA Astrophysics Data System (ADS)
Xue, Shuai; Chen, Shanyong; Shi, Feng; Lu, Jinfeng
2016-09-01
Cylindrical mirrors are key optics of high-end equipment of national defense and scientific research such as high energy laser weapons, synchrotron radiation system, etc. However, its surface error test technology develops slowly. As a result, its optical processing quality can not meet the requirements, and the developing of the associated equipment is hindered. Computer Generated-Hologram (CGH) is commonly utilized as null for testing cylindrical optics. However, since the fabrication process of CGH with large aperture is not sophisticated yet, the null test of cylindrical optics with large aperture is limited by the aperture of the CGH. Hence CGH null test combined with sub-aperture stitching method is proposed to break the limit of the aperture of CGH for testing cylindrical optics, and the design of CGH for testing cylindrical surfaces is analyzed. Besides, the misalignment aberration of cylindrical surfaces is different from that of the rotational symmetric surfaces since the special shape of cylindrical surfaces, and the existing stitching algorithm of rotational symmetric surfaces can not meet the requirements of stitching cylindrical surfaces. We therefore analyze the misalignment aberrations of cylindrical surfaces, and study the stitching algorithm for measuring cylindrical optics with large aperture. Finally we test a cylindrical mirror with large aperture to verify the validity of the proposed method.
Sackaloo, Kareisha; Strouse, Emily; Rice, Martin S
2015-04-01
The objective of this study was to determine whether reaching for objects with varying levels of preference associated with them elicited influenced motor control in a reaching task. Forty healthy adults were asked to reach for seven different types of candy, which they ranked by personal preference from being the most preferred to the least preferred. In this repeated measures design, data were analyzed on 39 participants who tended to demonstrate greater movement efficiency in movement time and movement units when reaching for candy in which they associated with greater preference (p < .0 167). Although no differences were found between conditions with peak velocity and percentage of movement time to peak velocity (p > .0167), these dependent variables appeared to trend in the direction of similar movement efficiency. Therapists can use this knowledge to help guide clinical reasoning when designing treatment plans and approaches. Future research is needed to further examine intensity along the continuum of preference and its implications for occupational therapy practice.
Circadian preference in bipolar disorder.
Giglio, Larriany Maria Falsin; Magalhães, Pedro V S; Andersen, Mônica Levy; Walz, Julio Cesar; Jakobson, Lourenço; Kapczinski, Flávio
2010-06-01
A role for circadian rhythm abnormalities in the pathogenesis of bipolar disorder (BD) has been suggested. The present study assessed circadian preference, a subjective preference for activities in the morning or evening related to chronotype. The sample was comprised of 81 outpatients with BD in remission and 79 control subjects. Circadian preference was derived from an interview evaluating biological rhythms and sleep pattern from the Pittsburgh Sleep Quality Index. Patients were significantly more likely to have an evening preference than control subjects. Circadian preference was also associated with sleep latency. The association of evening preference and longer sleep latency may be related to the frequent clinical observation of a sleep/wake cycle reversal in bipolar disorder.
Heightened sour preferences during childhood.
Liem, Djin Gie; Mennella, Julie A
2003-02-01
Basic research has revealed that the chemical sensory world of children is different from that of adults, as evidenced by their heightened preferences for sweet and salty tastes. However, little is known about the ontogeny of sour taste preferences, despite the growing market of extreme sour candies. The present study investigated whether the level of sourness most preferred in a food matrix and the ability to discriminate differences in sour intensity differed between 5- to 9-year-old children and their mothers, by using a rank-by-elimination procedure embedded in the context of a game. Mothers also completed a variety of questionnaires and children were asked several questions to assess whether children's temperament and food preferences and habits related to sour preferences. The results indicated that, although every mother and all but two of the children (92%) were able to rank the gelatins from most to least sour, more than one-third (35%) of the children, but virtually none of the adults, preferred the high levels of sour taste (0.25 M citric acid) in gelatin. Those children who preferred the extreme sour tastes were significantly less food neophobic (P < 0.05) and tended to experience a greater variety of fruits when compared with the remaining children (P = 0.11). Moreover, the children's preference for sour tastes generalized to other foods, such as candies and lemons, as reported by both children and mothers. These findings are the first experimental evidence to demonstrate that sour taste preferences are heightened during childhood and that such preferences are related to children's food habits and preferences. Further research is needed to unfold the relationship between the level of sour taste preferred and the actual consumption of sour-tasting foods and flavors in children.
Heightened Sour Preferences During Childhood
Liem, Djin Gie; Mennella, Julie A.
2009-01-01
Basic research has revealed that the chemical sensory world of children is different from that of adults, as evidenced by their heightened preferences for sweet and salty tastes. However, little is known about the ontogeny of sour taste preferences, despite the growing market of extreme sour candies. The present study investigated whether the level of sourness most preferred in a food matrix and the ability to discriminate differences in sour intensity differed between 5- to 9-year-old children and their mothers, by using a rank-by-elimination procedure embedded in the context of a game. Mothers also completed a variety of questionnaires and children were asked several questions to assess whether children’s temperament and food preferences and habits related to sour preferences. The results indicated that, although every mother and all but two of the children (92%) were able to rank the gelatins from most to least sour, more than one-third (35%) of the children, but virtually none of the adults, preferred the high levels of sour taste (0.25 M citric acid) in gelatin. Those children who preferred the extreme sour tastes were significantly less food neophobic (P < 0.05) and tended to experience a greater variety of fruits when compared with the remaining children (P = 0.11). Moreover, the children’s preference for sour tastes generalized to other foods, such as candies and lemons, as reported by both children and mothers. These findings are the first experimental evidence to demonstrate that sour taste preferences are heightened during childhood and that such preferences are related to children’s food habits and preferences. Further research is needed to unfold the relationship between the level of sour taste preferred and the actual consumption of sour-tasting foods and flavors in children. PMID:12588738
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
Stress analysis in cylindrical composition-gradient electrodes of lithium-ion battery
NASA Astrophysics Data System (ADS)
Zhong, Yaotian; Liu, Yulan; Wang, B.
2017-07-01
In recent years, the composition-gradient electrode material has been verified to be one of the most promising materials in lithium-ion battery. To investigate diffusion-induced stresses (DIS) generated in a cylindrical composition-gradient electrode, the finite deformation theory and the stress-induced diffusion hypothesis are adopted to establish the constitutive equations. Compared with stress distributions in a homogeneous electrode, the increasing forms of Young's modulus E(R) and partial molar volume Ω(R) from the electrode center to the surface along the radial direction drastically increase the maximal magnitudes of hoop and axial stresses, while both of the decreasing forms are able to make the stress fields smaller and flatter. Also, it is found that the slope of -1 for E(R) with that of -0.5 for Ω(R) is a preferable strategy to prevent the inhomogeneous electrode from cracking, while for the sake of protecting the electrode from compression failure, the optimal slope for inhomogeneous E(R) and the preferential one for Ω(R) are both -0.5. The results provide a theoretical guidance for the design of composition-gradient electrode materials.
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…
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…
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…
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…
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…
Aesthetic Preference for Human Figures.
ERIC Educational Resources Information Center
McWhinnie, H. J.
This study reports descriptive and correlational data relative to the aesthetic preferences for the human figure on the Salkind Art Preference Test (SAPT). The study is an example of the descriptive aesthetic method in which methods, descriptive statistics, and factor analysis are employed to explore the relationships among specific works of art…
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.
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…
Children's Reading Preferences in Fiction.
ERIC Educational Resources Information Center
Norris, Rob; And Others
1979-01-01
Children, ages 8-9 and 11-12, rated fiction they had just read. Boys preferred supernatural, adventure and mystery stories while girls rated fairy and pony stories highly. Both preferred characters of their own sex. Sex differences were smaller in the 11-12 age group (f=fiche number). (CP)
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…
Parent Preference of Preschool Children
ERIC Educational Resources Information Center
Lynn, David B.; Cross, Amy De Palma
1974-01-01
In individual sessions with 150 preschool children aged two through four, youngsters were asked to choose which parent (in the next room) they wanted to participate with them in each of seven play activities. Boys showed a strong father preference. Girls showed no parent preference when age groups were combined, but younger girls preferred…
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.
Interaction of cylindrically converging diffracted shock with uniform interface
NASA Astrophysics Data System (ADS)
Liang, Yu; Ding, Juchun; Zhai, Zhigang; Si, Ting; Luo, Xisheng
2017-08-01
The Richtmyer-Meshkov instability of an unperturbed air/SF6 interface subjected to a diffracted shock is experimentally studied by high-speed schlieren photography under cylindrical circumstances. The cylindrically converging diffracted shock (CCDS) is produced by a cylindrically uniform shock diffracting around a rigid cylinder(s), and the unperturbed interface is created by a soap film technique. The effects of coupling of multiple rigid cylinders and diverse spacings from the cylinder to interface on a flow field are highlighted. Schlieren images indicate that the amplitude of disturbances on the CCDS increases compared with the local shock radius. After the CCDS impact, a bulge is derived from the interface due to the shock-shock interaction inside the interface, and the number of bulges depends upon the number of cylinders. As the number of cylinders increases, the bulge becomes less pronounced, which is ascribed to additional shock-shock interactions inside the volume. As the distance between the cylinder and interface increases, an air cavity is first observed before the formation of a bulge. The amplitude of perturbation on the interface is found to reduce before the central reflected shock arrival because of the Rayleigh-Taylor stabilization effect. Through equating the pre-interface disturbance of the CCDS to the pre-shock perturbation of the perturbed interface, the initially linear growth rate is theoretically computed based on the impulsive model considering the Bell-Plesset effect. The theoretical results are found to deviate greatly from the experimental counterparts. Instead, taking the post-shock interface amplitude as an initial interface amplitude, the model works well. Therefore, the interface perturbations produced are notably smaller than the disturbances causing them. Moreover, the nonlinear behavior of perturbation growth is estimated by the model considering the Rayleigh-Taylor effect.
Experimental Determination of Stress Intensity in a Cracked Cylindrical Specimen,
1980-05-01
ADA098 336 MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA) F/O 20/11 A9 7 EPERIMENTAL DETERMINATION OF STRESS INTENSITY IN A CRACKED CYL-ETC(fl...DETERMINATION OF STRESS INTENSITY IN A CRACKED CYLINDRICAL SPECIMEN Graham Clark Approved for Public Release L9 R’ROD.CE A~j SELL ?H!S nEPOR I ©COMMONWEALTH...OF AUSTRALIA 1980 MAY, 1980 DEPARTMENT OF DEFENCE MATERIALS RESEARCH LABORATORIES REPORT LIMRL-R-77k _EXERMENALDETERMINATION OF STRESS INTENSITY: ON A
3D impurity inspection of cylindrical transparent containers
NASA Astrophysics Data System (ADS)
Kragh, Mikkel; Bjerge, Kim; Ahrendt, Peter
2017-01-01
This paper presents a method for automatically detecting and three-dimensionally positioning particles based on sequences of 2D images of rotating cylindrical transparent containers. The method can be used in the manufacturing industry by distinguishing between particles residing inside or outside a closed container. A foreign particle on the inside is a cause of rejection, whereas a particle on the outside might represent harmless dirt. The proposed method detects, tracks and positions particles and classifies containers accordingly as either rejected or accepted. Experimental results have shown an accuracy of 85% on a test set of 20 containers and an average execution time per container of 1 s.
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.
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.
Controlling the Plasma Flow in the Miniaturized Cylindrical Hall Thruster
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.
Buckling of circular cylindrical shells under axial compression.
NASA Technical Reports Server (NTRS)
Budiansky, B.; Hutchinson, J. W.
1972-01-01
The infinitely long cylindrical shell under axial compression with axisymmetric sinusoidal imperfections is considered. The bifurcation problem is formulated exactly, and a complete family of buckling modes is identified. Koiter's (1963) upper bound pertains to the critical stress associated with one restricted set of modes, and the critical stress for a set of long wavelength modes reproduces some numerical results obtained by Almroth (1966). The initial postbuckling analysis is also formulated exactly. An exact analytical solution is obtained for the limiting case of modes with infinitely long wavelengths, and numerical analysis is used to solve the equations for the other cases. An appendix gives the details of the analysis.
Cylindrical plasmas generated by an annular beam of ultraviolet light
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.
Improved approximate formulas for flux from cylindrical and rectangular sources
Wallace, O.J.; Bokharee, S.A.
1993-03-01
This report provides two new approximate formulas for the flux at detector points outside the radial and axial extensions of a homogeneous cylindrical source and improved approximate formulas for the flux at points opposite rectangular surface sources. These formulas extend the range of geometries for which analytic approximations may be used by shield design engineers to make rapid scoping studies and check more extensive calculations for reasonableness. These formulas can be used to support skeptical, independent evaluations and are also valuable teaching tools for introducing shield designers to complex shield analyses.
Experimental comparison of symmetry in rugby and cylindrical holhraums
NASA Astrophysics Data System (ADS)
Philippe, Franck; Tassin, Veronique; Laffite, Stephane; Monteil, Marie-Christine; Bastian, Josiane; Lours, Laurence; Villette, Bruno; Stemmler, Philippe; Bednarczyk, Sophie; Reneaume, Benoit; di Nicola, Pascale; Raffin, Vincent
2007-11-01
Recently, holhraum shape optimization has been investigated as a practical way to achieve ignition at lower energy [1][2]. Rugby shaped holhraums theoretically allow better energetic coupling and symmetry control than classical cylinders. As a first step toward an experimental validation of this design, this talk presents the results of experiments on the OMEGA laser facility dedicated to the comparison of symmetry in cylindrical and rugby holhraums. Foamball radiographs and Symcaps emission contours for both type of holhraums are compared to numerical simulation results. [1] M. Vandenboomgaerde et al., accepted by Phys. Rev. Lett. [2] P. Amendt et al., Phys. Plasmas 14, 056312 (2007)
Self shielding in cylindrical fissile sources in the APNea system
Hensley, D.
1997-02-01
In order for a source of fissile material to be useful as a calibration instrument, it is necessary to know not only how much fissile material is in the source but also what the effective fissile content is. Because uranium and plutonium absorb thermal neutrons so Efficiently, material in the center of a sample is shielded from the external thermal flux by the surface layers of the material. Differential dieaway measurements in the APNea System of five different sets of cylindrical fissile sources show the various self shielding effects that are routinely encountered. A method for calculating the self shielding effect is presented and its predictions are compared with the experimental results.
Bifurcation of solutions of a field-reversed cylindrical model
Lara, L.; Fontan, C.F.; Gratton, F.T.
1986-07-01
It is shown that the self-consistent solutions of Vlasov steady states for the double delta distribution model of cylindrical field-reversed configurations, generated by large ion orbits, have bifurcations within a definite interval of values for the total number of ions. The conjugate states have the same number of particles and the same radius of confinement but different azimuthal canonical momentum, orbit patterns, and magnetic fields. It is also shown that the states with a lower canonical momentum have a smaller energy content.
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.
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.
Infrared cylindrical cloak in nanosphere dispersed liquid crystal metamaterial.
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.
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.
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.
Application of cylindrical Langmuir probes to streaming plasma diagnostics.
NASA Technical Reports Server (NTRS)
Segall, S. B.; Koopman, D. W.
1973-01-01
The current-voltage characteristics of cylindrical probes in a high velocity collisionless plasma flow have been investigated experimentally and theoretically. The plasma was generated by a focused laser pulse incident on a metallic target in vacuum. An analysis, developed from a stationary plasma analog to the flowing case, demonstrated a failure of plasma shielding of probe potential in the electron attracting region. Modifications of relatively simple previous treatments were found to be valid for computing electron current to a probe. The electron characteristics derived from the present analysis agree well with experimental results. The ion and electron portions of the characteristics are consistent with each other and with independent diagnostic measurements.
Thermo-elastoviscoplastic snapthrough behavior of cylindrical panels
NASA Technical Reports Server (NTRS)
Song, Y.; Simitses, G. J.
1992-01-01
The thermo-elastoviscoplastic snapthrough behavior of simply supported cylindrical panels is investigated. The analysis is based on nonlinear kinematic relations and nonlinear rate-dependent unified constitutive equations which include both Bodner-Partom's and Walker's material models. A finite element approach is employed to predict the inelastic buckling behavior. Numerical examples are given to demonstrate the effects of several parameters which include the temperature, thickness and flatness of the panel. Comparisons of buckling responses between Bodner-Partom's model and Walker's model are given. The creep buckling behavior, as an example of time-dependent inelastic deformation, is also presented.
Experimental Investigations of Compressed Sandwich Composite/Honeycomb Cylindrical Shells
NASA Astrophysics Data System (ADS)
Muc, A.; Stawiarski, A.; Romanowicz, P.
2017-06-01
This article explains in some details the behaviour of thick, deep cylindrical sandwich panels subjected to compressive loads. In general, experimental results indicated that two different forms of failure have been observed - the first corresponds to the overall buckling and the second to the facesheet wrinkling. The obtained experimentally damages of shells are verified and validated with the use of the FE analysis, 2-D and 3-D both in the linear and non-linear approach. The unidirectional strain gauges were applied to detect the initiation of the overall buckling mode.
Liquid inflow to initially empty cylindrical tanks in low gravity
NASA Technical Reports Server (NTRS)
Spuckler, C. M.
1972-01-01
An experimental investigation was performed to determine the characteristics of liquid inflow to initially empty cylindrical tanks in a low gravity environment. The acceleration was varied so that Bond numbers based on the inlet radius varied from 0.059 to 2.80. The liquid entered the tank as a jet that grew to a maximum height and then decreased in height with respect to the bottom of the tank, with the liquid from the jet collecting in the bottom of the tank. The maximum jet heights were correlated in terms of the Weber number and the Bond number.
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.
WSRC Am/Cm Stabilization Program - Cylindrical Induction Melter Studies
Henderson, W.A.
1999-02-17
1.1.1 Kilogram quantities of Americium and Curium isotopes (Am/Cm) have been produced at the U.S. Department of Energy (DOE), Savannah River Site (SRS), Aiken, South Carolina. These highly radioactive isotopes have both government and commercial value and are currently stored as a nitric acid solution at the Savannah River Site. The material represents the largest source term in the F canyon at SRS. It is proposed that the Am/Cm material be vitrified to stabilize the material for long term, recoverable storage. This paper reviews the progress made during the process development phase of this program using the Cylindrical Induction Melter.
The RT Instability in Cylindrical Implosion of A Jelly Ring
NASA Astrophysics Data System (ADS)
Libing, Yang; Haidong, Liao; Chengwei, Sun; Kai, Ouyang; Jun, Li; Xianbin, Huang
2002-12-01
The interfacial RT instability experiments on imploding jelly liners in cylindrically convergent geometry have been performed. The liner's instability growth was observed clearly with a high-speed framing camera. Jelly liners had different initial perturbation forms on their inner and outer interfaces, smooth one or sinusoidal one. The initial perturbations also had different magnitude and spatial frequency ( for example, mode n=5, 10, 20 ). The experimental results show that the growth and coupling of perturbations on inner and outer surface are remarkably different. Meanwhile, the relevant 2D numerical simulation of hydrodynamics combined with Level Set method has been performed.
Stability analysis of doubly regenerative cylindrical grinding process
NASA Astrophysics Data System (ADS)
Liu, Zhaoheng; Payre, Guy
2007-04-01
In this paper, we investigate the stability properties of a cylindrical grinding process. The dynamical model of the process includes two inherent delayed forcing terms, one from workpiece regeneration and the other from grinding wheel regeneration. The prediction of chatter onset is carried out by computing the spectrum of the doubly delayed differential equations for any set of physical and operational parameters. Stability diagrams are plotted in parameter space. The stability behavior obtained from this analysis is verified to be consistent with direct simulation results. A sensitivity analysis approach is also proposed, and can be used to lead an unstable process to a stable state by optimally varying one of the operational parameters.
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.
Formation of prominences by condensation modes in magnetized cylindrical plasmas
NASA Technical Reports Server (NTRS)
An, C.-H.
1985-01-01
Condensation modes in a magnetized cylindrical plasma are studied to shed light on the formation and stability of solar prominences. A rigorous mathematical derivation of the perturbation equation is developed, and the effect of field twist on the stability is studied for an equilibrium with uniform field twist, in which temperature increases, but density does not, as pressure increases. The results imply that prominences may form in globally magnetohydrodynamic-stable magnetic loops with very low field twist. Also, prominences are more likely to form in a region of weaker area-averaged magnetic field.
Radiation from a charge rotating inside a cylindrical grating
NASA Astrophysics Data System (ADS)
Kotanjyan, A. S.; Mkrtchyan, A. R.; Saharian, A. A.
2017-07-01
We investigate the spectral-angular distribution for the radiation emitted by a point charge moving along a helical trajectory inside a cylindrical grating with conducting strips. Two types of the radiation processes are realized: undulator and Smith-Purcell radiations. Their relative contributions to the total radiation intensity are discussed in various asymptotic regions of the parameters describing the diffraction grating and for large harmonics. The region of the parameters is specified for which the interference effects between the undulator and Smith-Purcell radiations are essential.
Polar POLICRYPS diffractive structures generate cylindrical vector beams
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.
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.
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.
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.
An experimental investigation of flame behavior during cylindrical vessel explosions
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.
Asymptotic approximations for pure bending of thin cylindrical shells
NASA Astrophysics Data System (ADS)
Coman, Ciprian D.
2017-08-01
A simplified partial wrinkling scenario for in-plane bending of thin cylindrical shells is explored by using several asymptotic strategies. The eighth-order boundary eigenvalue problem investigated here originates in the Donnel-Mushtari-Vlasov shallow shell theory coupled with a linear membrane pre-bifurcation state. It is shown that the corresponding neutral stability curve is amenable to a detailed asymptotic analysis based on the method of multiple scales. This is further complemented by an alternative WKB approximation that provides comparable information with significantly less effort.
Preliminary analysis techniques for ring and stringer stiffened cylindrical shells
NASA Astrophysics Data System (ADS)
Graham, J.
1993-03-01
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.
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.
Optical trapping of nanotubes with cylindrical vector beams.
Donato, M G; Vasi, S; Sayed, R; Jones, P H; Bonaccorso, F; Ferrari, A C; Gucciardi, P G; Maragò, O M
2012-08-15
We use laser beams with radial and azimuthal polarization to optically trap carbon nanotubes. We measure force constants and trap parameters as a function of power showing improved axial trapping efficiency with respect to linearly polarized beams. The analysis of the thermal fluctuations highlights a significant change in the optical trapping potential when using cylindrical vector beams. This enables the use of polarization states to shape optical traps according to the particle geometry, as well as paving the way to nanoprobe-based photonic force microscopy with increased performance compared to a standard linearly polarized configuration.
Light sheet based on one-dimensional Airy beam generated by single cylindrical lens
NASA Astrophysics Data System (ADS)
Cao, Zhaolou; Zhai, Chunjie; Li, Jinhua; Xian, Fenglin; Pei, Shixin
2017-06-01
We report on a novel method of generating light sheet with extended depth of field based on one-dimensional Airy beam by the use of single cylindrical lens. In the method, coma is intentionally introduced into the system by oblique illumination to approximate a cubic phase mask. Experimental studies were presented to validate this method. This technique can be easily applied to current light sheet generators where cylindrical lens is used, as only tilt of the cylindrical lens is needed.
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.
Progress on Diamond-Based Cylindrical Dielectric Accelerating Structures
Kanareykin, A.; Schoessow, P.; Conde, M.; Gai, W.
2006-11-27
The development of a high gradient diamond-based cylindrical dielectric loaded accelerator (DLA) is presented. A diamond-loaded DLA can potentially sustain accelerating gradients far in excess of the limits experimentally observed for conventional metallic accelerating structures. The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerators: high rf breakdown level, extremely low dielectric losses and the highest available thermoconductive coefficient. We used the hot-filament Chemical Vapor Deposition (CVD) process to produce high quality 5-10 cm long cylindrical diamond layers. Our collaboration has also been developing a new method of CVD diamond surface preparation that reduces the secondary electron emission coefficient below unity. Special attention was paid to the numerical optimization of the waveguide to structure rf coupling section, where the surface magnetic and electric fields were minimized relative to the accelerating gradient and within known metal surface breakdown limits. We conclude with a brief overview of the use of diamond microstructures for use in compact rf sources.
An evaluation of active noise control in a cylindrical shell
NASA Technical Reports Server (NTRS)
Silcox, R. J.; Lester, H. C.; Abler, S. B.
1989-01-01
The physical mechanisms governing the use of active noise control in an extended volume of a cylindrical shell are discussed. Measured data was compared with computer results from a previously derived analytical model based on an infinite shell theory. For both the analytical model and experiment, the radiation of the external monopoles is coupled to the internal acoustic field through the radial displacement of the thin, elastic cylindrical shell. An active noise control system was implemented in the cylinder using a fixed array of discrete monopole sources, all of which lie in the plane of the exterior noise sources. Good agreement between measurement and prediction was obtained for both internal pressure response and overall noise reduction. Attenuations in the source plane greater than 15 dB were recorded along with a uniformly quieted noise environment over the entire length of the experimental model. Results indicate that for extended axial forcing distributions or very low shell damping, axial arrays of control sources may be required. Finally, the Nyquist criteria for the number of azimuthal control sources is shown to provide for effective control over the full cylinder cross section.
An evaluation of active noise control in a cylindrical shell
NASA Technical Reports Server (NTRS)
Silcox, R. J.; Lester, H. C.; Abler, S. B.
1987-01-01
The physical mechanisms governing the use of active noise control in an extended volume of a cylindrical shell are discussed. Measured data was compared with computer results from a previously derived analytical model based on an infinite shell theory. For both the analytical model and experiment, the radiation of the external monopoles is coupled to the internal acoustic field through the radial displacement of the thin, elastic cylindrical shell. An active noise control system was implemented in the cylinder using a fixed array of discrete monopole sources, all of which lie in the plane of the exterior noise sources. Good agreement between measurement and prediction was obtained for both internal pressure response and overall noise reduction. Attenuations in the source plane greater than 15 dB were recorded along with a uniformly quieted noise environment over the entire length of the experimental model. Results indicate that for extended axial forcing distributions or very low shell damping, axial arrays of control sources may be required. Finally, the Nyquist criteria for the number of azimuthal control sources is shown to provide for effective control over the full cylinder cross section.
Ultrasound cylindrical phased array for transoesophageal thermal therapy: initial studies.
Melodelima, David; Lafon, Cyril; Prat, Frederic; Birer, Alain; Cathignol, Dominique
2002-12-07
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.
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.
Liquid bridging of cylindrical colloids in near-critical solvents
NASA Astrophysics Data System (ADS)
Labbé-Laurent, M.; Law, A. D.; Dietrich, S.
2017-09-01
Within mean field theory, we investigate the bridging transition between a pair of parallel cylindrical colloids immersed in a binary liquid mixture as a solvent that is close to its critical consolute point Tc. We determine the universal scaling functions of the effective potential and of the force between the colloids. For a solvent that is at the critical concentration and close to Tc, we find that the critical Casimir force is the dominant interaction at close separations. This agrees very well with the corresponding Derjaguin approximation for the effective interaction between the two cylinders, while capillary forces originating from the extension of the liquid bridge turn out to be more important at large separations. In addition, we are able to infer from the wetting characteristics of the individual colloids the first-order transition of the liquid bridge connecting two colloidal particles to the ruptured state. While specific to cylindrical colloids, the results presented here also provide an outline for identifying critical Casimir forces acting on bridged colloidal particles as such and for analyzing the bridging transition between them.
On the optimal pretensioning of cylindrical and spherical pressure vessels
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.
The magnetic field of a permanent hollow cylindrical magnet
NASA Astrophysics Data System (ADS)
Reich, Felix A.; Stahn, Oliver; Müller, Wolfgang H.
2016-09-01
Based on the rational version of M AXWELL's equations according to T RUESDELL and T 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 M 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.
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.
On Sector Magnets or Transverse Electromagnetic Fields in Cylindrical Coordinates
Zolkin, Timofey
2016-03-10
The Laplace's equations for the scalar and vector potentials describing electric or magnetic fields in cylindrical coordinates with translational invariance along azimuthal coordinate are considered. The series of special functions which, when expanded in power series in radial and vertical coordinates, in lowest order replicate the harmonic homogeneous polynomials of two variables are found. These functions are based on radial harmonics found by Edwin~M.~McMillan in his more-than-40-years "forgotten" article, which will be discussed. In addition to McMillan's harmonics, second family of adjoint radial harmonics is introduced, in order to provide symmetric description between electric and magnetic fields and to describe fields and potentials in terms of same special functions. Formulas to relate any transverse fields specified by the coefficients in the power series expansion in radial or vertical planes in cylindrical coordinates with the set of new functions are provided. This result is no doubt important for potential theory while also critical for theoretical studies, design and proper modeling of sector dipoles, combined function dipoles and any general sector element for accelerator physics. All results are presented in connection with these problems.
Array gain for a cylindrical array with baffle scatter effects.
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.
Investigation of a scanned cylindrical ultrasound system for breast hyperthermia.
Ju, Kuen-Cheng; Tseng, Li-Te; Chen, Yung-Yaw; Lin, Win-Li
2006-02-07
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.
Parity violating cylindrical shell in the framework of QED
NASA Astrophysics Data System (ADS)
Fialkovsky, I. V.; Markov, V. N.; Pis'mak, Yu M.
2008-02-01
We present calculations of Casimir energy (CE) in a system of quantized electromagnetic (EM) field interacting with an infinite circular cylindrical shell (which we call 'the defect'). Interaction is described in the only QFT-consistent way by Chern-Simon action concentrated on the defect, with a single coupling constant a. For the regularization of UV divergencies of the theory, we use the Pauli-Villars regularization of the free-EM action. The divergencies are extracted as a polynomial in the regularization mass M, and they renormalize the classical part of the surface action. We reveal the dependence of CE on the coupling constant a. Corresponding Casimir force is attractive for all values of a. For a → ∞, we reproduce the known results for CE for perfectly conducting cylindrical shell first obtained by DeRaad and Milton. As a future task for solving existing arguments on observational status of (rigid) self-pressure of a single object, we propose for investigation a system which we call 'Casimir drum'.
Experimental study on vibrations of a nonwoven fabric cylindrical filter
NASA Astrophysics Data System (ADS)
Chiba, M.; Kawahara, T.; Michiue, S.; Shintani, Y.
2011-11-01
Unexpected vibrations on a cylindrical filter made of nonwoven fabrics were clarified experimentally. Two types of filter with length L=1.8 m and 3.7 m, both 45 cm in diameter and 1.08 mm in thickness, were used. This is a new type of aeroelastic vibration phenomenon because the filter is a closed cylindrical vessel. In addition, the flow velocity of inner air was very slow and inner air flowed out slowly from the filter surface. The velocity distribution of air flow from a fan duct as well as the frequency and amplitude of the filter vibration were measured for two types of filter. By setting up a roll core panel at the outlet of the fan duct, we could rectify the outflow and suppressed the vibration of the shorter filter with L=1.8 m. However, this method was not adequate for the longer filter with L=3.7 m, and we could suppress the vibration by shielding the inner surface of the filter at the top region.
Double layer in a cylindrical hollow-cathode discharge
Abu-Hashem, A.; Abd Al-Halim, M. A. Hassouba, M. A.; Masoud, M. M.
2010-03-15
A dc cylindrical coaxial glow discharge with an inner grid anode has been studied. The region between the two electrodes is seen dark, while a brightly glowing region forms inside the grid anode up to the center. The current-voltage characteristic of a dc cylindrical glow discharge in nitrogen is similar to that of a normal glow discharge, while the normal glow discharge voltage decreases with increasing pressure. The minimum plasma potentials are observed in the hollow cathode region due to the accumulation of electrons at the back of the grid anode. At the center, some of the passed electrons are converged, so their potential is decreased. These electrons have a sufficient time to be redistributed to form one group with a Maxwellian electron energy distribution function. The electron temperature measured by electric probes varies from 1.6 to 3.6 eV, while the plasma density varies from 3.9 x 10{sup 16} to 7 x 10{sup 13} m{sup -3}, depending on the discharge current and probe position. The plasma density increases as the electrons move radially from the grid toward the central region, while their temperature decreases.
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.
Acoustic mode coupling of two facing, shallow cylindrical cavities
NASA Astrophysics Data System (ADS)
McCarthy, Philip; Ekmekci, Alis
2016-11-01
Cavity mode excitation by grazing flows is a well-documented source for noise generation. Similarly to their rectangular equivalents, single cylindrical cavities have been shown to exhibit velocity dependent self-sustaining feedback mechanisms that produce significant tonal noise. The present work investigates the effect of cavity mode coupling on the tonal noise generation for two facing, shallow cylindrical cavities. This geometric arrangement may occur for constrained flows, such as those within ducts, silencers or between aircraft landing gear wheels. For the latter configuration, the present study has observed that the tonal frequency dependence upon the freestream Mach number, associated with the single cavity feedback mechanism, no longer holds true. Instead, two simultaneously present and distinct large amplitude tones that are independent (in frequency) of speed, propagate to the far field. These two, fixed frequency tones are attributable to the first order transverse mode, and the first order transverse and azimuthal modes for the two combined cavities and the volume between them. Altering either the cavity aspect ratio or the inter-cavity spacing thus changes the acoustic resonant volume and translates the centre frequencies of the observed tones correspondingly. The authors would like to thank Bombardier and Messier-Bugatti-Dowty for their continued support.
Spherical/cylindrical laser scanner for geometric reverse engineering
NASA Astrophysics Data System (ADS)
Chan, Vincent H.; Samaan, Medhat
2004-04-01
Laser scanners are often used in geometric reverse engineering to generate a CAD drawing out of an existing physical part. This often requires careful path planning to ensure the correct stand-off distance of the sensor, to prevent any collisions of the sensor with the target object and to prevent any scan occlusions in the resulting data. A dedicated system was constructed to collect data using a 3-axis cylindrical/prismatic device. The benefit of this scanning system is the ability to scan completely around the target object, including the bottom of the object. A stripe-type laser diode is used along with a CCD camera. The target object sits on a transparent plexi-glass table, which can be rotated 360 degrees. Both the laser and the CCD are mounted on an arm, such that they can be traversed along a linear path, as well as being rotated 360° around the table. This permits the device to scan in either spherical or cylindrical paths with 360° rotation around the target object. This system allows for the quick scanning of any object while minimizing the number of occlusions in the resulting scan data.
A portable cylindrical electrostatic fusion device for neutronic tomography
Gu, Y.B.; Javedani, J.B.; Miley, G.H.
1994-11-01
A portable cylindrical electrostatic fusion device (C-device) was developed. Earlier studies have focused on spherical geometry. Here the authors discuss a related, but radically different cylindrical version which offers great promise for application requiring that geometry. The C-device, operating in a plasma glow discharge mode, has produced neutrons at 106 neutrons/sec for D-D fusion (equivalent to 10{sup 8} neutrons/sec for D-T fusion). When used as a neutron generator, the C-device is well suited for tomographic diagnosis. Such a neutron generator would have advantages over both a beam-solid target generator and a neutron-emanating isotope. Advantages over a beam-solid target include lower estimated capital cost, longer life expectancy; over an isotope are an on/off capability, minimal radioactive inventory, variable source strength, self-calibrating capability, no storage shield. A detailed description of the device along with preliminary experimental data and an analysis of neutron yield vs. different operating parameters will be presented.
Orbital motion theory and operational regimes for cylindrical emissive probes
NASA Astrophysics Data System (ADS)
Chen, Xin; Sanchez-Arriaga, G.
2017-02-01
A full-kinetic model based on the orbital-motion theory for cylindrical emissive probes (EPs) is presented. The conservation of the distribution function, the energy, and the angular momentum for cylindrical probes immersed in collisionless and stationary plasmas is used to write the Vlasov-Poisson system as a single integro-differential equation. It describes self-consistently the electrostatic potential profile and, consequently, the current-voltage (I-V) probe characteristics. Its numerical solutions are used to identify different EP operational regimes, including orbital-motion-limited (OML)/non-OML current collection and monotonic/non-monotonic potential, in the parametric domain of probe bias and emission level. The most important features of the potential and density profiles are presented and compared with common approximations in the literature. Conventional methods to measure plasma potential with EPs are briefly revisited. A direct application of the model is to estimate plasma parameters by fitting I-V measurements to the theoretical results.
Implosion of Cylindrical Cavities via Short Duration Impulsive Loading
NASA Astrophysics Data System (ADS)
Huneault, Justin; Higgins, Andrew
2014-11-01
An apparatus has been developed to study the collapse of a cylindrical cavity in gelatin subjected to a symmetric impact-driven impulsive loading. A gas-driven annular projectile is accelerated to approximately 50 m/s, at which point it impacts a gelatin casting confined by curved steel surfaces that allow a transition from an annular geometry to a cylindrically imploding motion. The implosion is visualized by a high-speed camera through a window which forms the top confining wall of the implosion cavity. The initial size of the cavity is such that the gelatin wall is two to five times thicker than the impacting projectile. Thus, during impact the compression wave which travels towards the cavity is closely followed by a rarefaction resulting from the free surface reflection of the compression wave in the projectile. As the compression wave in the gelatin reaches the inner surface, it will also reflect as a rarefaction wave. The interaction between the rarefaction waves from the gelatin and projectile free surfaces leads to large tensile stresses resulting in the spallation of a relatively thin shell. The study focuses on the effect of impact parameters on the thickness and uniformity of the imploding shell formed by the cavitation in the imploding gelatin cylinder.
Liquid bridging of cylindrical colloids in near-critical solvents.
Labbé-Laurent, M; Law, A D; Dietrich, S
2017-09-14
Within mean field theory, we investigate the bridging transition between a pair of parallel cylindrical colloids immersed in a binary liquid mixture as a solvent that is close to its critical consolute point Tc. We determine the universal scaling functions of the effective potential and of the force between the colloids. For a solvent that is at the critical concentration and close to Tc, we find that the critical Casimir force is the dominant interaction at close separations. This agrees very well with the corresponding Derjaguin approximation for the effective interaction between the two cylinders, while capillary forces originating from the extension of the liquid bridge turn out to be more important at large separations. In addition, we are able to infer from the wetting characteristics of the individual colloids the first-order transition of the liquid bridge connecting two colloidal particles to the ruptured state. While specific to cylindrical colloids, the results presented here also provide an outline for identifying critical Casimir forces acting on bridged colloidal particles as such and for analyzing the bridging transition between them.
Vibration of in-vacuo elliptic cylindrical shells
NASA Astrophysics Data System (ADS)
Boisvert, Jeffrey E.; Hayek, Sabih I.
2003-10-01
The equations of motion for the vibration of elliptic cylindrical shells of constant thickness were derived using a Galerkin approach. The elastic strain energy density used in this derivation has seven independent kinematic variables: three displacements, two thickness-shear, and two thickness-stretch. The resulting seven coupled algebraic equations are symmetric and positive definite. The shell has a constant thickness, h, finite length, L, and is simply supported at its ends, (z=0,L), where z is the axial coordinate. The elliptic cross-section is defined by the shape parameter, a, and the half-length of the major axis, l. The modal solutions are expanded in a doubly infinite series of comparison functions in terms of circular functions in the angular and axial coordinates. The natural frequencies and the mode shapes were obtained by the Galerkin method. Numerical results were obtained for several h/l and L/l ratios, and various shape parameters, including the limiting case of a simply supported cylindrical shell (a=100). [Work supported by ONR and the Navy/ASEE Summer Faculty Program.
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.
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.
Tunable cylindrical shell as an element in acoustic metamaterial.
Titovich, Alexey S; Norris, Andrew N
2014-10-01
Elastic cylindrical shells are fitted with an internal mechanism which is optimized so that, in the quasi-static regime, the combined system exhibits prescribed effective acoustic properties. The mechanism consists of a central mass supported by an axisymmetric distribution of elastic stiffeners. By appropriate selection of the mass and stiffness of the internal mechanism, the shell's effective acoustic properties (bulk modulus and density) can be tuned as desired. Subsonic flexural waves excited in the shell by the attachment of stiffeners are suppressed by including a sufficiently large number of such stiffeners. The effectiveness of the proposed metamaterial is demonstrated by matching the properties of a thin aluminum shell with a polymer insert to those of water. The scattering cross section in water is nearly zero over a broad range of frequencies at the lower end of the spectrum. By arranging the tuned shells in an array the resulting acoustic metamaterial is capable of steering waves. As an example, a cylindrical-to-plane wave lens is designed by varying the bulk modulus in the array according to the conformal mapping of a unit circle to a square.
An evaluation of active noise control in a cylindrical shell
NASA Technical Reports Server (NTRS)
Silcox, R. J.; Lester, H. C.; Abler, S. B.
1989-01-01
The physical mechanisms governing the use of active noise control in an extended volume of a cylindrical shell are discussed. Measured data was compared with computer results from a previously derived analytical model based on an infinite shell theory. For both the analytical model and experiment, the radiation of the external monopoles is coupled to the internal acoustic field through the radial displacement of the thin, elastic cylindrical shell. An active noise control system was implemented in the cylinder using a fixed array of discrete monopole sources, all of which lie in the plane of the exterior noise sources. Good agreement between measurement and prediction was obtained for both internal pressure response and overall noise reduction. Attenuations in the source plane greater than 15 dB were recorded along with a uniformly quieted noise environment over the entire length of the experimental model. Results indicate that for extended axial forcing distributions or very low shell damping, axial arrays of control sources may be required. Finally, the Nyquist criteria for the number of azimuthal control sources is shown to provide for effective control over the full cylinder cross section.
Development of a collapsible reinforced cylindrical space observation window
NASA Technical Reports Server (NTRS)
Khan, A. Q.
1971-01-01
Existing material technology was applied to the development of a collapsible transparent window suitable for manned spacecraft structures. The effort reported encompasses the evaluation of flame retardants intended for use in the window matrix polymer, evaluation of reinforcement angle which would allow for a twisting pantographing motion as the cylindrical window is mechanically collapsed upon itself, and evaluation of several reinforcement embedment methods. A fabrication technique was developed to produce a reinforced cylindrical space window of 45.7 cm diameter and 61.0 cm length. The basic technique involved the application of a clear film on a male-section mold; winding axial and girth reinforcements and vacuum casting the outer layer. The high-strength transparent window composite consisted of a polyether urethane matrix reinforced with an orthogonal pattern of black-coated carbon steel wire cable. A thin film of RTV silicone rubber was applied to both surfaces of the urethane. The flexibility, retraction system, and installation system are described.
Machine Tool User Cylindrical Die Rolling Performance Support System
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.
Three-dimensional nanocomposite scaffolds with ordered cylindrical orthogonal pores.
Rodríguez Hernández, José Carlos; Serrano Aroca, Angel; Gómez Ribelles, José Luis; Pradas, Manuel Monleón
2008-02-01
A silica reinforcement can improve the mechanical properties of hydrogels in the rubbery state. A method to prepare a scaffold with a well-ordered array of cylindrical pores is presented in this work, which yields a scaffold with a biphasic matrix of a hybrid nanocomposite: the hydrogel poly(2-hydroxyethyl acrylate) (PHEA) and a silica network obtained by an acid catalyzed sol-gel process of tetraethoxysilane (TEOS). As porogenic template of the scaffold stacked layers of commercial polyamide 6 fabrics were used, which were compressed and sintered. Porosity and dynamic mechanical response of the resulting scaffolds were measured and compared with the bulk properties. Removal of the organic polymer phase of the scaffold by pyrolysis revealed the overall continuity of the silica network; the residue maintained the original cylindrical pore structure of the scaffolds, though slightly shrunk. Atomic force microscopy topography measurements of these pyrolysed residues revealed a silica structure with particle aggregates having sizes around tens of nanometers. The silica distribution was assessed by X-ray microanalysis mapping, showing homogeneity at a micrometer scale. (c) 2007 Wiley Periodicals, Inc.
Sector magnets or transverse electromagnetic fields in cylindrical coordinates
Zolkin, T.
2017-04-10
Laplace’s equation is considered for scalar and vector potentials describing electric or magnetic fields in cylindrical coordinates, with invariance along the azimuthal coordinate. In a series, we found special functions which, when expanded to lowest order in power series in radial and vertical coordinates, replicate harmonic polynomials in two variables. These functions are based on radial harmonics found by Edwin M. McMillan forty years ago. In addition to McMillan’s harmonics, a second family of radial harmonics is introduced to provide a symmetric description between electric and magnetic fields and to describe fields and potentials in terms of the same functions.more » Formulas are provided which relate any transverse fields specified by the coefficients in the power series expansion in radial or vertical planes in cylindrical coordinates with the set of new functions. Our result is important for potential theory and for theoretical study, design and proper modeling of sector dipoles, combined function dipoles and any general sector element for accelerator physics. All results are presented in connection with these problems.« less
Shock interaction behind a pair of cylindrical obstacles
NASA Astrophysics Data System (ADS)
Liu, Heng; Mazumdar, Raoul; Eliasson, Veronica
2014-11-01
The body of work focuses on two-dimensional numerical simulations of shock interaction with a pair of cylindrical obstacles, varying the obstacle separation and incident shock strength. With the shock waves propagating parallel to the center-line between the two cylindrical obstacles, the shock strengths simulated vary from a Mach of 1.4 to a Mach of 2.4, against a wide range of obstacle separation distance to their diameters. These cases are simulated via a software package called Overture, which is used to solve the inviscid Euler equations of gas dynamics on overlapping grids with adaptive mesh refinement. The goal of these cases is to find a so-called ``safe'' region for obstacle spacing and varying shock Mach numbers, such that the pressure in the ``safe'' region is reduced downstream of the obstacles. The benefits apply to both building and armor design for the purpose of shock wave mitigation to keep humans and equipment safe. The results obtained from the simulations confirm that the length of the ``safe'' region and the degree of shock wave attenuation depend on the ratio of obstacle separation distance to obstacle diameter. The influence of various Mach number is also discussed.
A cylindrical specimen holder for electron cryo-tomography
Palmer, Colin M.; Löwe, Jan
2014-01-01
The use of slab-like flat specimens for electron cryo-tomography restricts the range of viewing angles that can be used. This leads to the “missing wedge” problem, which causes artefacts and anisotropic resolution in reconstructed tomograms. Cylindrical specimens provide a way to eliminate the problem, since they allow imaging from a full range of viewing angles around the tilt axis. Such specimens have been used before for tomography of radiation-insensitive samples at room temperature, but never for frozen-hydrated specimens. Here, we demonstrate the use of thin-walled carbon tubes as specimen holders, allowing the preparation of cylindrical frozen-hydrated samples of ribosomes, liposomes and whole bacterial cells. Images acquired from these cylinders have equal quality at all viewing angles, and the accessible tilt range is restricted only by the physical limits of the microscope. Tomographic reconstructions of these specimens demonstrate that the effects of the missing wedge are substantially reduced, and could be completely eliminated if a full tilt range was used. The overall quality of these tomograms is still lower than that obtained by existing methods, but improvements are likely in future. PMID:24275523
An experimental study on compressible cylindrical cavity flows
NASA Astrophysics Data System (ADS)
Chung, Kung-Ming; Lee, Kuan-Huang; Lebiga, Vadim; Zinoviev, Vitali
2016-10-01
Experiments were performed to study the characteristics of compressible cylindrical cavity flows. The diameter-to-depth ratio is an important parameter in determining the characteristics inside a cylindrical cavity and its vicinity. Closed-type cavity flow has lower amplitude of mean surface pressure behind the front wall and higher one ahead of the rear wall of the cavity. The amplitude of surface pressure fluctuations increases toward the rear face for an open-type cavity, whereas an additional peak near the middle of cavity floor is observed for a closed-type cavity. The diameter-to-depth ratio affects the characteristics of pressure distribution of a cavity, while the freestream Mach number effect is less significant. By taking Fourier transform analysis of the data near the trailing edge of a cavity, resonant modes are observed in open- and transitional-cavity flows. These modes are well-predicted by the Rossiter's empirical equation developed for rectangular cavities. Furthermore, the dominant mode switches to a higher mode as Mach number increases.
Sector magnets or transverse electromagnetic fields in cylindrical coordinates
NASA Astrophysics Data System (ADS)
Zolkin, T.
2017-04-01
Laplace's equation is considered for scalar and vector potentials describing electric or magnetic fields in cylindrical coordinates, with invariance along the azimuthal coordinate. A series of special functions are found which, when expanded to lowest order in power series in radial and vertical coordinates, replicate harmonic polynomials in two variables. These functions are based on radial harmonics found by Edwin M. McMillan forty years ago. In addition to McMillan's harmonics, a second family of radial harmonics is introduced to provide a symmetric description between electric and magnetic fields and to describe fields and potentials in terms of the same functions. Formulas are provided which relate any transverse fields specified by the coefficients in the power series expansion in radial or vertical planes in cylindrical coordinates with the set of new functions. This result is important for potential theory and for theoretical study, design and proper modeling of sector dipoles, combined function dipoles and any general sector element for accelerator physics. All results are presented in connection with these problems.
Research on a lubricating grease print process for cylindrical cylinder
NASA Astrophysics Data System (ADS)
Yang, Liu; Zhang, Xuan; Wang, XianYan; Tan, XiaoYan
2017-09-01
In vehicle braking system and clutch system of transmission, there is always a kind of cylindrical component dose reciprocating motion. The main working method is the reciprocating motion between the rubber sealing parts and cylindrical parts, the main factor affects the service life of the product is the lubricating performance of the moving parts. So the lubricating performance between cylinders and rubber sealing rings is particularly important, same as the quality of the grease applies on the surface of the surface of cylinder. Traditional method of manually applying grease has some defects such as applying unevenly, applying tools like brush and cloth easily falls off and affect the cleanness of products, contact skin easily cause allergy, waste grease due to the uncontrollable of grease quantity using in applying, low efficiency of manual operation. An automatic, quantitative and high pressure applying equipment is introduced in this document to replace the traditional manually applying method, which can guarantee the applying quality of the grease which are painted on the surface of cylinder and bring economic benefits to the company.
X-ray Spectroscopy of Directly Driven Cylindrical Implosions
NASA Astrophysics Data System (ADS)
Haynes, D.; Hooper, C.; Delamater, N.; Barnes, C.; Oertel, J.; Pollak, G.; Tubbs, D.; Watt, R.; Boehly, T.; Bradley, D.; Jaanimagi, P.; Knauer, J.
1998-11-01
X-ray spectra from a chlorinated polystyrene marker layer in a series of directly driven cylindrical implosions are presented and analyzed. The 4μm thick, 500μm long C_8H_6Cl2 (1.42g/cc) annular spectroscopic tracer layer is centrally located on the interior surface of the 20μm thick, 2250μm long polystyrene (1.044g/cc) 860μ m inner diameter cylindrical shell. The shell is filled with polystyrene foam (60mg/cc).(Barnes, C. W., et al.) 1998, to be published in Rev. Sci. Instrum., Tubbs, D. L., et al. 1998, to be published in Lasers and Particle Beams The implosions are driven by 50 beams of the OMEGA Laser facility. The temperature and density sensitive K-shell Cl spectra are recorded by a time-resolved spectrograph, and compared to calculated spectra in order to infer the evolution of electron temperature and density in the marker layer.(This work was performed under the auspices of the U. S. Department of Energy by the Los Alamos National Laboratory under contract No. W-7405-Eng-36)
Micro-photonic cylindrical waveguide based protein biosensor
NASA Astrophysics Data System (ADS)
Padigi, Sudhaprasanna Kumar; Asante, Kofi; Sekhar Reddy Kovvuri, Vijay; Kiran Kondama Reddy, Ravi; La Rosa, Andres; Prasad, Shalini
2006-09-01
In this paper we experimentally demonstrate the fabrication and operation of a rapidly prototyped optical cylindrical micro-waveguide based biosensor. This device works on the principle of variation to the light intensity and path of coupled input light due to the binding of protein bio-molecules onto the micro-waveguide surface as a method of physical transduction. The variation to the coupled light intensity and path is dependent on the nature of the bio-molecule and the density of the bio-molecules. This technique has been used to identify protein biomarkers for inflammation and thrombosis, namely myeloperoxidase (MPO) and C-reactive protein (CRP). The detection limit that has been demonstrated is pg ml-1. The detection speed is of the order of seconds from the time of injection of the bio-molecule. The optical signature that is obtained to identify a protein bio-molecule is entirely dependent on the nature of adsorption of the bio-molecule on to the cylindrical cavity surfaces. This in turn is dependent on the protein conformation and the surface charge of the bio-molecules. Hence a specific protein bio-molecule generates a unique optical identifier based on the nature of binding/adsorption to the cavity surface. This physical phenomenon is exploited to identify individual proteins. This technique is a demonstration of detection of nano-scale protein bio-molecules using the optical biosensor technique with unprecedented sensitivity.
Employing a cylindrical single crystal in gas-surface dynamics.
Hahn, Christine; Shan, Junjun; Liu, Ying; Berg, Otto; Kleijn, Aart W; Juurlink, Ludo B F
2012-03-21
We describe the use of a polished, hollow cylindrical nickel single crystal to study effects of step edges on adsorption and desorption of gas phase molecules. The crystal is held in an ultra-high vacuum apparatus by a crystal holder that provides axial rotation about a [100] direction, and a crystal temperature range of 89 to 1100 K. A microchannel plate-based low energy electron diffraction/retarding field Auger electron spectrometer (AES) apparatus identifies surface structures present on the outer surface of the cylinder, while a separate double pass cylindrical mirror analyzer AES verifies surface cleanliness. A supersonic molecular beam, skimmed by a rectangular slot, impinges molecules on a narrow longitudinal strip of the surface. Here, we use the King and Wells technique to demonstrate how surface structure influences the dissociation probability of deuterium at various kinetic energies. Finally, we introduce spatially-resolved temperature programmed desorption from areas exposed to the supersonic molecular beam to show how surface structures influence desorption features.
Residual Stress Measurements of Explosively Clad Cylindrical Pressure Vessels
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.
On the physics of propagating Bessel modes in cylindrical waveguides
NASA Astrophysics Data System (ADS)
Gómez-Correa, J. E.; Balderas-Mata, S. E.; Coello, V.; Puente, N. P.; Rogel-Salazar, J.; Chávez-Cerda, S.
2017-05-01
In this paper, we demonstrate that by using a mathematical physics approach—focusing attention on the physics and using mathematics as a tool—it is possible to visualize the formation of the transverse modes inside a cylindrical waveguide. The opposite (physical mathematics) approach looks at the mathematical problem and then tries to impose a physical interpretation. For cylindrical waveguides, the physical mathematics route leads to the Bessel differential equation, and it is argued that in the core of the waveguide there are only Bessel functions of the first kind in the description of the transverse modes. The Neumann functions are deemed non-physical due to their singularity at the origin and are eliminated from the final description of the solution. In this paper, by combining geometric optics and wave optics concepts, we show that the inclusion of the Neumann function is physically necessary to describe fully and properly the formation of the propagating transverse modes. With this approach, we also show that the field outside a dielectric waveguide arises in a natural way.
Gas Temperature Effects on Electrical Breakdown in Cylindrical Electrodes
NASA Astrophysics Data System (ADS)
Uhm, Han; Jung, She
2002-11-01
One of the most important applications of atmospheric pressure plasma is in the corona discharge system, for the potential reduction of NOx and SOx gas emissions from diesel engines. However, the conventional corona discharge system for the emission control application requires a high electrical voltage (typically 45 kV or higher), making its high voltage modulator heavy and bulky with insulating material. We, therefore, investigate the influence of the gas temperature on the electrical breakdown properties in the cylindrical electrode system. A theoretical model of the electrical breakdown in a cylindrical electrode system is briefly summarized, by making use of Paschen¡¯s law. The breakdown voltage increases, reaches its peak and decreases, as the aspect ratio a/b increases from 0.01 to unity, where a and b are radii of the inner and outer electrodes, respectively. The experimental data agree remarkably well with the theoretical predictions. The breakdown voltage V in a high gas temperature Tg is given by V = (Tr/Tg)V0, where V0 is the breakdown voltage at the room temperature Tr. Obviously, the breakdown voltage decreases as the gas temperature Tg increases. The experimental data agree well with the theoretical values. It is, therefore, concluded that the breakdown voltage is inversely proportional to the gas temperature Tg as predicted from the theoretical analysis.
Simulated, Theoretical and Experimental Shock Trajectories in Cylindrical Geometry
NASA Astrophysics Data System (ADS)
Kanzleiter, R.; Atchison, W.; Bowers, R.; Guzik, J.
2002-07-01
The current work compares computations and similarity relations for convergent shocks with experimental data from cylindrical implosions on the Shiva Star capacitor bank at AFRL (Air Force Research Laboratory). The experiment consisted of a 1 mm thick cylindrical aluminum liner that is magnetically imploded onto a central target. The central target contains an inner Lucite cylinder surrounded by an outer Sn layer. The target was designed using the Eulerian hydrodynamics code RAGE in 2- and 3D. One-dimensional models of the liner driver utilizing the RAVEN MHD code set the initial liner/target interaction parameters for the RAGE simulations. Shock breakout from the Sn/Lucite interface and subsequent propagation within the Lucite are measured to provide experimental data for code validation. Radial convergence is examined through comparisons with similarity solutions. Comparison of experimentally measured timing data and simulated shock trajectories will be discussed. Further efforts compare equation-of-state effects by utilizing an analytic Grueneisen EOS instead of the original SESAME tables.
Progress on Diamond-Based Cylindrical Dielectric Accelerating Structures
NASA Astrophysics Data System (ADS)
Kanareykin, A.; Schoessow, P.; Conde, M.; Gai, W.
2006-11-01
The development of a high gradient diamond-based cylindrical dielectric loaded accelerator (DLA) is presented. A diamond-loaded DLA can potentially sustain accelerating gradients far in excess of the limits experimentally observed for conventional metallic accelerating structures. The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerators: high rf breakdown level, extremely low dielectric losses and the highest available thermoconductive coefficient. We used the hot-filament Chemical Vapor Deposition (CVD) process to produce high quality 5-10 cm long cylindrical diamond layers. Our collaboration has also been developing a new method of CVD diamond surface preparation that reduces the secondary electron emission coefficient below unity. Special attention was paid to the numerical optimization of the waveguide to structure rf coupling section, where the surface magnetic and electric fields were minimized relative to the accelerating gradient and within known metal surface breakdown limits. We conclude with a brief overview of the use of diamond microstructures for use in compact rf sources.
Observation of Compressible Plasma Mix in Cylindrically Convergent Implosions
NASA Astrophysics Data System (ADS)
Barnes, Cris W.; Batha, Steven H.; Lanier, Nicholas E.; Magelssen, Glenn R.; Tubbs, David L.; Dunne, A. M.; Rothman, Steven R.; Youngs, David L.
2000-10-01
An understanding of hydrodynamic mix in convergent geometry will be of key importance in the development of a robust ignition/burn capability on NIF, LMJ and future pulsed power machines. We have made use of the OMEGA laser facility at the University of Rochester to investigate directly the mix evolution in a convergent geometry, compressible plasma regime. The experiments comprise a plastic cylindrical shell imploded by direct laser irradiation. The cylindrical shell surrounds a lower density plastic foam which provides sufficient back pressure to allow the implosion to stagnate at a sufficiently high radius to permit quantitative radiographic diagnosis of the interface evolution near turnaround. The susceptibility to mix of the shell-foam interface is varied by choosing different density material for the inner shell surface (thus varying the Atwood number). This allows the study of shock-induced Richtmyer-Meshkov growth during the coasting phase, and Rayleigh-Taylor growth during the stagnation phase. The experimental results will be described along with calculational predictions using various radiation hydrodynamics codes and turbulent mix models.
Finite deformations of an electroelastic circular cylindrical tube
NASA Astrophysics Data System (ADS)
Melnikov, Andrey; Ogden, Ray W.
2016-12-01
In this paper the theory of nonlinear electroelasticity is used to examine deformations of a pressurized thick-walled circular cylindrical tube of soft dielectric material with closed ends and compliant electrodes on its curved boundaries. Expressions for the dependence of the pressure and reduced axial load on the deformation and a potential difference between, or uniform surface charge distributions on, the electrodes are obtained in respect of a general isotropic electroelastic energy function. To illustrate the behaviour of the tube, specific forms of energy functions accounting for different mechanical properties coupled with a deformation independent quadratic dependence on the electric field are used for numerical purposes, for a given potential difference and separately for a given charge distribution. Numerical dependences of the non-dimensional pressure and reduced axial load on the deformation are obtained for the considered energy functions. Results are then given for the thin-walled approximation as a limiting case of a thick-walled cylindrical tube without restriction on the energy function. The theory described herein provides a general basis for the detailed analysis of the electroelastic response of tubular dielectric elastomer actuators, which is illustrated for a fixed axial load in the absence of internal pressure and fixed internal pressure in the absence of an applied axial load.
Cylindrical acoustical holography applied to full-scale jet noise.
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.
Cylindrical electron acoustic solitons for modified time-fractional nonlinear equation
NASA Astrophysics Data System (ADS)
Abdelwahed, H. G.; El-Shewy, E. K.; Mahmoud, Abeer A.
2017-08-01
The modulation of cylindrical electron acoustic characteristics using a time fractal modified nonlinear equation has been investigated in nonisothermal plasmas. The time fractional cylindrical modified-Korteweg-de Vries equation has been obtained by Agrawal's analysis. A cylindrical localized soliton has been obtained via the Adomian decomposition method. The pressure term and cylindrical time fractional effects on the modulated wave properties have been investigated with comparative auroral observations. It is established that the presence of the fractional order factor not only significantly modifies the solitary characteristics but also varies the profile polarity.
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.
76 FR 53631 - BioPreferred Program
Federal Register 2010, 2011, 2012, 2013, 2014
2011-08-29
... biobased preferred procurement program (one part of the BioPreferred Program) is available on the Internet... Rule The USDA BioPreferred Program provides for the preferred procurement of biobased products by Federal agencies as well as a voluntary labeling program for biobased products. The BioPreferred Program...
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.
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.
A bio-inspired microstructure induced by slow injection moulding of cylindrical block copolymers.
Stasiak, Joanna; Brubert, Jacob; Serrani, Marta; Nair, Sukumaran; de Gaetano, Francesco; Costantino, Maria Laura; Moggridge, Geoff D
2014-08-28
It is well known that block copolymers with cylindrical morphology show alignment with shear, resulting in anisotropic mechanical properties. Here we show that well-ordered bi-directional orientation can be achieved in such materials by slow injection moulding. This results in a microstructure, and anisotropic mechanical properties, similar to many natural tissues, making this method attractive for engineering prosthetic fibrous tissues. An application of particular interest to us is prosthetic polymeric heart valve leaflets, mimicking the shape, microstructure and hence performance of the native valve. Anisotropic layers have been observed for cylinder-forming block copolymers centrally injected into thin circular discs. The skin layers exhibit orientation parallel to the flow direction, whilst the core layer shows perpendicularly oriented domains; the balance of skin to core layers can be controlled by processing parameters such as temperature and injection rate. Heart valve leaflets with a similar layered structure have been prepared by injection moulding. Numerical modelling demonstrates that such complex orientation can be explained and predicted by the balance of shear and extensional flow.