Microvolume index of refraction determinations by interferometric backscatter

NASA Astrophysics Data System (ADS)

Bornhop, Darryl J.

1995-06-01

A new method has been applied to the determination of fluid bulk properties in small detection volumes. Through the use of an unfocused He-Ne laser beam and a cylindrical tube of capillary dimensions, relative refractive-index measurements are possible. The backscattered light from the illumination of a tube of capillary dimensions produces an interference pattern that is spatially defined and that contains information related to the bulk properties of the fluid contained in the tube. Positional changes in the intensity-modulated beam profile (interference fringes) are directly related to the refractive index of the fluid in the tube. The determination of dn/n at the 10-7 level is possible in probe volumes of 350 pL. The technique has been applied to tubes as small as 75 mu m inner diameter and as large as 1.0 mm inner diameter. No modification of the simple optical bench is required for facilitating the determination of refractive index for the complete range of tube diameters.

Electroform replication of grazing incidence X-ray optics. [spaceborne telescopes

NASA Technical Reports Server (NTRS)

Ulmer, M. P.; Purcell, W. R.; Bedford, D.; Simnett, G. R.

1985-01-01

Work to produce mirrors via electroform replication is reported. Work on small (6 cm by 9 cm) cylindrical pieces and on 40 cm long by 12 cm wide Wolter shaped mirrors is summarized. It is shown that electroforming is a viable technique for producing relatively inexpensive grazing incidence X-ray optics, as long as modest resolution (1 min of arc) and size (12 cm diameter by 40 cm long) are specified.

Cylindrical micelles of a POSS amphiphilic dendrimer as nano-reactors for polymerization.

PubMed

Weng, Jing-Ting; Yeh, Tso-Fan; Samuel, Ashok Zachariah; Huang, Yi-Fan; Sie, Jyun-Hao; Wu, Kuan-Yi; Peng, Chi-How; Hamaguchi, Hiro-O; Wang, Chien-Lung

2018-02-15

A low generation amphiphilic dendrimer, POSS-AD, which has a POSS core and eight amphiphilic arms, was synthesized and used as a nano-reactor to produce well-defined polymer nano-cylinders. Confirmed by small-angle X-ray scattering (SAXS), Raman and NMR spectrometry, monodispersed cylindrical micelles that contain a hydrophilic cavity with a diameter of 2.09 nm and a length of 4.26 nm were produced via co-assembling POSS-AD with hydrophilic liquids, such as H 2 O and HEMA in hydrophobic solvents. Taking the HEMA/POSS-AD cylindrical micelles as nano-reactors, polymerization of HEMA within the micelles results in polymer nano-cylinders (POSS-ADNPs) with a diameter of 2.24 nm and a length of 5.02 nm. The study confirmed that despite the inability to maintain specific shape in solution, low generation dendrimers form well-defined nano-containers or nano-reactors, which relies on co-assembling with hydrophilic guest molecules. These nano-reactors are robust enough to maintain their shape during the polymerization of the guest molecules. Polymer nano-cylinders with dimensions less than 10 nm can thus be produced from the HEMA/POSS-AD micelles. Since the chemical structure of low-generation dendrimers and the contents of the co-assembled nano-reactors can be easily adjusted, the concept holds the potential for the further developments of low-generation amphiphilic dendrimers.

Numerical and experimental study on buckling and postbuckling behavior of cracked cylindrical shells

NASA Astrophysics Data System (ADS)

Saemi, J.; Sedighi, M.; Shariati, M.

2015-09-01

The effect of crack on load-bearing capacity and buckling behavior of cylindrical shells is an essential consideration in their design. In this paper, experimental and numerical buckling analysis of steel cylindrical shells of various lengths and diameters with cracks have been studied using the finite element method, and the effect of crack position, crack orientation and the crack length-to-cylindrical shell perimeter ( λ = a/(2 πr)) and shell length-to-diameter ( L/ D) ratios on the buckling and post-buckling behavior of cylindrical shells has been investigated. For several specimens, buckling test was performed using an INSTRON 8802 servo hydraulic machine, and the results of experimental tests were compared to numerical results. A very good correlation was observed between numerical simulation and experimental results. Finally, based on the experimental and numerical results, sensitivity of the buckling load to the shell length, crack length and orientation has also been investigated.

Lateral mode coupling to reduce the electrical impedance of small elements required for high power ultrasound therapy phased arrays.

PubMed

Hynynen, Kullervo; Yin, Jianhua

2009-03-01

A method that uses lateral coupling to reduce the electrical impedance of small transducer elements in generating ultrasound waves was tested. Cylindrical, radially polled transducer elements were driven at their length resonance frequency. Computer simulation and experimental studies showed that the electrical impedance of the transducer element could be controlled by the cylinder wall thickness, while the operation frequency was determined by the cylinder length. Acoustic intensity (averaged over the cylinder diameter) over 10 W / cm(2) (a therapeutically relevant intensity) was measured from these elements.

Transurethral canine prostatectomy with a cylindrically diffusing fiber

NASA Astrophysics Data System (ADS)

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

1994-09-01

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

Flow rate of some pharmaceutical diluents through die-orifices relevant to mini-tableting.

PubMed

Kachrimanis, K; Petrides, M; Malamataris, S

2005-10-13

The effects of cylindrical orifice length and diameter on the flow rate of three commonly used pharmaceutical direct compression diluents (lactose, dibasic calcium phosphate dihydrate and pregelatinised starch) were investigated, besides the powder particle characteristics (particle size, aspect ratio, roundness and convexity) and the packing properties (true, bulk and tapped density). Flow rate was determined for three different sieve fractions through a series of miniature tableting dies of different orifice diameter (0.4, 0.3 and 0.2 cm) and thickness (1.5, 1.0 and 0.5 cm). It was found that flow rate decreased with the increase of the orifice length for the small diameter (0.2 cm) but for the large diameter (0.4 cm) was increased with the orifice length (die thickness). Flow rate changes with the orifice length are attributed to the flow regime (transitional arch formation) and possible alterations in the position of the free flowing zone caused by pressure gradients arising from the flow of self-entrained air, both above the entrance in the die orifice and across it. Modelling by the conventional Jones-Pilpel non-linear equation and by two machine learning algorithms (lazy learning, LL, and feed-forward back-propagation, FBP) was applied and predictive performance of the fitted models was compared. It was found that both FBP and LL algorithms have significantly higher predictive performance than the Jones-Pilpel non-linear equation, because they account both dimensions of the cylindrical die opening (diameter and length). The automatic relevance determination for FBP revealed that orifice length is the third most influential variable after the orifice diameter and particle size, followed by the bulk density, the difference between bulk and tapped densities and the particle convexity.

Inertial migrations of cylindrical particles in rectangular microchannels: Variations of equilibrium positions and equivalent diameters

NASA Astrophysics Data System (ADS)

Su, Jinghong; Chen, Xiaodong; Hu, Guoqing

2018-03-01

Inertial migration has emerged as an efficient tool for manipulating both biological and engineered particles that commonly exist with non-spherical shapes in microfluidic devices. There have been numerous studies on the inertial migration of spherical particles, whereas the non-spherical particles are still largely unexplored. Here, we conduct three-dimensional direct numerical simulations to study the inertial migration of rigid cylindrical particles in rectangular microchannels with different width/height ratios under the channel Reynolds numbers (Re) varying from 50 to 400. Cylindrical particles with different length/diameter ratios and blockage ratios are also concerned. Distributions of surface force with the change of rotation angle show that surface stresses acting on the particle end near the wall are the major contributors to the particle rotation. We obtain lift forces experienced by cylindrical particles at different lateral positions on cross sections of two types of microchannels at various Re. It is found that there are always four stable equilibrium positions on the cross section of a square channel, while the stable positions are two or four in a rectangular channel, depending on Re. By comparing the equilibrium positions of cylindrical particles and spherical particles, we demonstrate that the equivalent diameter of cylindrical particles monotonously increases with Re. Our work indicates the influence of a non-spherical shape on the inertial migration and can be useful for the precise manipulation of non-spherical particles.

A gilled mushroom, Gerontomyces lepidotus gen. et sp. nov. (Basidiomycota: Agaricales), in Baltic amber.

PubMed

Poinar, George

2016-09-01

A densely scaled small mushroom in Baltic amber is described as Gerontomyces lepidotus gen. et sp. nov. and is characterized by a convex pileus 1.0 mm in diameter, distant to subdistant lamellae with smooth margins and a centrally inserted cylindrical, solid stipe. Its taxonomic placement is uncertain. This is the first mushroom described from Baltic amber. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Photo-multiplier Tube Based Hybrid MRI and Frequency Domain Fluorescence Tomography System for Small Animal Imaging

PubMed Central

Lin, Y; Ghijsen, M T; Gao, H; Liu, N; Nalcioglu, O; Gulsen, G

2014-01-01

Fluorescence tomography (FT) is a promising molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. However, recovered fluorophore parameters highly depend on the size and depth of the object due to the ill-posedness of the FT inverse problem. Structural a priori information from another high spatial resolution imaging modality has been demonstrated to significantly improve FT reconstruction accuracy. In this study, we have constructed a combined magnetic resonance imaging (MRI) and FT system for small animal imaging. A photo-multiplier tube (PMT) is used as the detector to acquire frequency domain FT measurements. This is the first MR-compatible time-resolved FT system that can reconstruct both fluorescence concentration and lifetime maps simultaneously. The performance of the hybrid system is evaluated with phantom studies. Two different fluorophores, Indocyanine Green (ICG) and 3-3′ Diethylthiatricarbocyanine Iodide (DTTCI), which have similar excitation and emission spectra but different lifetimes, are utilized. The fluorescence concentration and lifetime maps are both reconstructed with and without the structural a priori information obtained from MRI for comparison. We show that the hybrid system can accurately recover both fluorescence intensity and lifetime within 10% error for two 4.2 mm-diameter cylindrical objects embedded in a 38 mm-diameter cylindrical phantom when MRI structural a priori information is utilized. PMID:21753235

Effect of Processing Pressure on Isolated Pore Formation during Controlled Directional Solidification in Small Channels

NASA Technical Reports Server (NTRS)

Cox, Matthew C.; Anilkumar, Amrutur V.; Grugel, RIchard N.; Lee, Chun P.

2008-01-01

Directional solidification experiments were performed, using succinonitrile saturated with nitrogen gas, to examine the effects of in-situ processing pressure changes on the formation growth, and evolution of an isolated, cylindrical gaseous pore. A novel solidification facility, capable of processing thin cylindrical samples (I.D. < 1.0 mm), under controlled pressure conditions, was used for the experiments. A new experimental method for growing the isolated pore from a seed bubble is introduced. The experimental results indicate that an in-situ processing pressure change will result in either a transient change in pore diameter or a complete termination of pore growth, indicating that pressure changes can be used as a control parameter to terminate bubble growth. A simple analytical model has been introduced to explain the experimental observations.

Photogrammetry experiments with a model eye.

PubMed Central

Rosenthal, A R; Falconer, D G; Pieper, I

1980-01-01

Digital photogrammetry was performed on stereophotographs of the optic nerve head of a modified Zeiss model eye in which optic cups of varying depths could be simulated. Experiments were undertaken to determine the impact of both photographic and ocular variables on the photogrammetric measurements of cup depth. The photogrammetric procedure tolerates refocusing, repositioning, and realignment as well as small variations in the geometric position of the camera. Progressive underestimation of cup depth was observed with increasing myopia, while progressive overestimation was noted with increasing hyperopia. High cylindrical errors at axis 90 degrees led to significant errors in cup depth estimates, while high cylindrical errors at axis 180 degrees did not materially affect the accuracy of the analysis. Finally, cup depths were seriously underestimated when the pupil diameter was less than 5.0 mm. Images PMID:7448139

Effect of the nozzle tip’s geometrical shape on electrospray deposition of organic thin films

NASA Astrophysics Data System (ADS)

Ueda, Hiroyuki; Takeuchi, Keita; Kikuchi, Akihiko

2017-04-01

Electrospray deposition (ESD) is a favorable wet fabrication technique for organic thin films. We investigated the effects of the nozzle tip’s geometrical shape on the spraying properties of an organic solution used for ESD. Five types of cylindrical metal nozzles with zero (flat end) to four protrusions at the tips were prepared for depositing a solution of a small-molecule compound, tris(8-hydroxyquinolinato)aluminum (Alq3) solution. We confirmed that the diameter of the deposited droplets and their size dispersion decreased with an increase in the number of protrusions. The area occupation ratio of small droplets with a diameter smaller than 2 µm increased from 21 to 83% as the number of protrusions was increased from zero to four. The surface roughness root mean square of 60-nm-thick Alq3 films substantially improved from 32.5 to 6.8 nm with increasing number of protrusions.

A Comparison of Four-Image Reconstruction Algorithms for 3-D PET Imaging of MDAPET Camera Using Phantom Data

NASA Astrophysics Data System (ADS)

Baghaei, H.; Wong, Wai-Hoi; Uribe, J.; Li, Hongdi; Wang, Yu; Liu, Yaqiang; Xing, Tao; Ramirez, R.; Xie, Shuping; Kim, Soonseok

2004-10-01

We compared two fully three-dimensional (3-D) image reconstruction algorithms and two 3-D rebinning algorithms followed by reconstruction with a two-dimensional (2-D) filtered-backprojection algorithm for 3-D positron emission tomography (PET) imaging. The two 3-D image reconstruction algorithms were ordered-subsets expectation-maximization (3D-OSEM) and 3-D reprojection (3DRP) algorithms. The two rebinning algorithms were Fourier rebinning (FORE) and single slice rebinning (SSRB). The 3-D projection data used for this work were acquired with a high-resolution PET scanner (MDAPET) with an intrinsic transaxial resolution of 2.8 mm. The scanner has 14 detector rings covering an axial field-of-view of 38.5 mm. We scanned three phantoms: 1) a uniform cylindrical phantom with inner diameter of 21.5 cm; 2) a uniform 11.5-cm cylindrical phantom with four embedded small hot lesions with diameters of 3, 4, 5, and 6 mm; and 3) the 3-D Hoffman brain phantom with three embedded small hot lesion phantoms with diameters of 3, 5, and 8.6 mm in a warm background. Lesions were placed at different radial and axial distances. We evaluated the different reconstruction methods for MDAPET camera by comparing the noise level of images, contrast recovery, and hot lesion detection, and visually compared images. We found that overall the 3D-OSEM algorithm, especially when images post filtered with the Metz filter, produced the best results in terms of contrast-noise tradeoff, and detection of hot spots, and reproduction of brain phantom structures. Even though the MDAPET camera has a relatively small maximum axial acceptance (/spl plusmn/5 deg), images produced with the 3DRP algorithm had slightly better contrast recovery and reproduced the structures of the brain phantom slightly better than the faster 2-D rebinning methods.

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.

Pressurized water nuclear reactor system with hot leg vortex mitigator

DOEpatents

Lau, Louis K. S.

1990-01-01

A pressurized water nuclear reactor system includes a vortex mitigator in the form of a cylindrical conduit between the hot leg conduit and a first section of residual heat removal conduit, which conduit leads to a pump and a second section of residual heat removal conduit leading back to the reactor pressure vessel. The cylindrical conduit is of such a size that where the hot leg has an inner diameter D.sub.1, the first section has an inner diameter D.sub.2, and the cylindrical conduit or step nozzle has a length L and an inner diameter of D.sub.3 ; D.sub.3 /D.sub.1 is at least 0.55, D.sub.2 is at least 1.9, and L/D.sub.3 is at least 1.44, whereby cavitation of the pump by a vortex formed in the hot leg is prevented.

Breakdown of hierarchical architecture in cellulose during dilute acid pretreatments.

PubMed

Zhang, Yan; Inouye, Hideyo; Yang, Lin; Himmel, Michael E; Tucker, Melvin; Makowski, Lee

Cellulose is an attractive candidate as a feedstock for sustainable bioenergy because of its global abundance. Pretreatment of biomass has significant influence on the chemical availability of cellulose locked in recalcitrant microfibrils. Optimizing pretreatment depends on an understanding of its impact on the microscale and nanoscale molecular architecture. X-ray scattering experiments have been performed on native and pre-treated maize stover and models of cellulose architecture have been derived from these data. Ultra small-angle, very small-angle and small-angle X-ray scattering (USAXS, VSAXS and SAXS) probe three different levels of architectural scale. USAXS and SAXS have been used to study cellulose at two distinct length scales, modeling the fibrils as ~30 Å diameter rods packed into ~0.14 μm diameter bundles. VSAXS is sensitive to structural features at length scales between these two extremes. Detailed analysis of diffraction patterns from untreated and pretreated maize using cylindrical Guinier plots and the derivatives of these plots reveals the presence of substructures within the ~0.14 μm diameter bundles that correspond to grouping of cellulose approximately 30 nm in diameter. These sub-structures are resilient to dilute acid pretreatments but are sensitive to pretreatment when iron sulfate is added. These results provide evidence of the hierarchical arrangement of cellulose at three length scales and the evolution of these arrangements during pre-treatments.

Breakdown of hierarchical architecture in cellulose during dilute acid pretreatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yan; Inouye, Hideyo; Yang, Lin

2015-02-28

Cellulose can work as a feedstock for sustainable bioenergy because of its global abundance. Pretreatment of biomass has significant influence on the chemical availability of cellulose locked in recalcitrant microfibrils. Optimizing pretreatment depends on an understanding of its impact on the microscale and nanoscale molecular architecture. X-ray scattering experiments have been performed on native and pre-treated maize stover and models of cellulose architecture have been derived from these data. Ultra small-angle, very small-angle and small-angle X-ray scattering (USAXS, VSAXS and SAXS) probe three different levels of architectural scale. USAXS and SAXS have been used to study cellulose at two distinctmore » length scales, modeling the fibrils as ~30 Å diameter rods packed into ~0.14 μm diameter bundles. VSAXS is sensitive to structural features at length scales between these two extremes. Detailed analysis of diffraction patterns from untreated and pretreated maize using cylindrical Guinier plots and the derivatives of these plots reveals the presence of substructures within the ~0.14 μm diameter bundles that correspond to grouping of cellulose approximately 30 nm in diameter. These sub-structures are resilient to dilute acid pretreatments but are sensitive to pretreatment when iron sulfate is added. Our results provide evidence of the hierarchical arrangement of cellulose at three length scales and the evolution of these arrangements during pre-treatments.« less

Breakdown of hierarchical architecture in cellulose during dilute acid pretreatments

DOE PAGES

Zhang, Yan; Inouye, Hideyo; Yang, Lin; ...

2015-02-28

Cellulose is an attractive candidate as a feedstock for sustainable bioenergy because of its global abundance. Pretreatment of biomass has significant influence on the chemical availability of cellulose locked in recalcitrant microfibrils. Optimizing pretreatment depends on an understanding of its impact on the microscale and nanoscale molecular architecture. X-ray scattering experiments have been performed on native and pre-treated maize stover and models of cellulose architecture have been derived from these data. Ultra small-angle, very small-angle and small-angle X-ray scattering (USAXS, VSAXS and SAXS) probe three different levels of architectural scale. USAXS and SAXS have been used to study cellulose atmore » two distinct length scales, modeling the fibrils as ~30 Å diameter rods packed into ~0.14 μm diameter bundles. VSAXS is sensitive to structural features at length scales between these two extremes. Detailed analysis of diffraction patterns from untreated and pretreated maize using cylindrical Guinier plots and the derivatives of these plots reveals the presence of substructures within the ~0.14 μm diameter bundles that correspond to grouping of cellulose approximately 30 nm in diameter. These sub-structures are resilient to dilute acid pretreatments but are sensitive to pretreatment when iron sulfate is added. Lastly, these results provide evidence of the hierarchical arrangement of cellulose at three length scales and the evolution of these arrangements during pre-treatments.« less

Continuous-Flow Electrophoresis of DNA and Proteins in a Two-Dimensional Capillary-Well Sieve.

PubMed

Duan, Lian; Cao, Zhen; Yobas, Levent

2017-09-19

Continuous-flow electrophoresis of macromolecules is demonstrated using an integrated capillary-well sieve arranged into a two-dimensional anisotropic array on silicon. The periodic array features thousands of entropic barriers, each resulting from an abrupt interface between a 2 μm deep well (channel) and a 70 nm capillary. These entropic barriers owing to two-dimensional confinement within the capillaries are vastly steep in relation to those arising from slits featuring one-dimensional confinement. Thus, the sieving mechanisms can sustain relatively large electric field strengths over a relatively small array area. The sieve rapidly sorts anionic macromolecules, including DNA chains and proteins in native or denatured states, into distinct trajectories according to size or charge under electric field vectors orthogonally applied. The baseline separation is achieved in less than 1 min within a horizontal migration length of ∼1.5 mm. The capillaries are self-enclosed conduits in cylindrical profile featuring a uniform diameter and realized through an approach that avoids advanced patterning techniques. The approach exploits a thermal reflow of a layer of doped glass for shape transformation into cylindrical capillaries and for controllably shrinking the capillary diameter. Lastly, atomic layer deposition of alumina is introduced for the first time to fine-tune the capillary diameter as well as to neutralize the surface charge, thereby suppressing undesired electroosmotic flows.

An experimental study of the reflection from spherical and flat ended cylindrical targets suitable for fetal Doppler performance assessment.

PubMed

Preston, R C; Bond, A D

1997-01-01

The performance of small-diameter targets suitable for use as oscillating targets for testing the sensitivity of Doppler fetal heartbeat detectors has been systematically studied. Experimental results are presented in the 1.6-3.0 MHz frequency range for the plane-wave reflection loss for a total of 16 targets: spherical balls made of stainless steel; hemispherical-ended rods made of PTFE; and flat-ended rods made of stainless steel, PTFE, polycarbonate, and tungsten carbide. Results show that the fine-structure variation of reflection loss with frequency is greatest in the case of spherical ball targets and least for flat-ended targets. It has been shown that, providing care is taken during manufacture, the reflection loss from a flat-ended target can be predicted using a simple theory based on a plane disc reflector. Tungsten carbide targets consisting of a long rod with a diameter of 1.6 mm tapered down to a cylindrical flat end with a diameter of 0.4, 0.5, and 0.6 mm have been shown to provide reflection losses of between 60 and 40 dB, and to have a smooth variation of reflection loss with frequency. They can also be manufactured in a form that allows no significant interference from the supporting structure and, therefore, are ideal targets to meet the requirements of International Electrotechnical Commission 1266:1995.

Laboratory simulation of cratering on small bodies

NASA Technical Reports Server (NTRS)

Schmidt, Robert M.

1991-01-01

A new technique using external pressure was developed to simulate the lithostatic pressure due to self-gravity of small bodies. A 13-in. diameter cylindrical test chamber with L/D of 1 was fabricated to accommodate firing explosive charges with gas overpressures of up to 6000 psi. The chamber was hydrotested to 9000 psi. The method allows much larger scale factors that can be obtained with existing centrifuges and has the correct spherical geometry of self gravity. A simulant for jointed rock to be used in this fixture was developed using weakly cemented basalt. Various strength/pressure scaling theories can now be examined and tested.

Conformal SiO2 coating of sub-100 nm diameter channels of polycarbonate etched ion-track channels by atomic layer deposition

PubMed Central

Sobel, Nicolas; Lukas, Manuela; Spende, Anne; Stühn, Bernd; Trautmann, Christina

2015-01-01

Summary Polycarbonate etched ion-track membranes with about 30 µm long and 50 nm wide cylindrical channels were conformally coated with SiO2 by atomic layer deposition (ALD). The process was performed at 50 °C to avoid thermal damage to the polymer membrane. Analysis of the coated membranes by small angle X-ray scattering (SAXS) reveals a homogeneous, conformal layer of SiO2 in the channels at a deposition rate of 1.7–1.8 Å per ALD cycle. Characterization by infrared and X-ray photoelectron spectroscopy (XPS) confirms the stoichiometric composition of the SiO2 films. Detailed XPS analysis reveals that the mechanism of SiO2 formation is based on subsurface crystal growth. By dissolving the polymer, the silica nanotubes are released from the ion-track membrane. The thickness of the tube wall is well controlled by the ALD process. Because the track-etched channels exhibited diameters in the range of nanometres and lengths in the range of micrometres, cylindrical tubes with an aspect ratio as large as 3000 have been produced. PMID:25821688

Aspherical bubble dynamics and oscillation times

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godwin, R.P.; Chapyak, E.J.; Noack, J.

1999-03-01

The cavitation bubbles common in laser medicine are rarely perfectly spherical and are often located near tissue boundaries, in vessels, etc., which introduce aspherical dynamics. Here, novel features of aspherical bubble dynamics are explored. Time-resolved experimental photographs and simulations of large aspect ratio (length:diameter {approximately}20) cylindrical bubble dynamics are presented. The experiments and calculations exhibit similar dynamics. A small high-pressure cylindrical bubble initially expands radially with hardly any axial motion. Then, after reaching its maximum volume, a cylindrical bubble collapses along its long axis with relatively little radial motion. The growth-collapse period of these very aspherical bubbles differs only sightlymore » from twice the Rayleigh collapse time for a spherical bubble with an equivalent maximum volume. This fact justifies using the temporal interval between the acoustic signals emitted upon bubble creation and collapse to estimate the maximum bubble volume. As a result, hydrophone measurements can provide an estimate of the bubble energy even for aspherical bubbles. The prolongation of the oscillation period of bubbles near solid boundaries relative to that of isolated spherical bubbles is also discussed.« less

The influence of the blood vessel diameter on the full scattering profile from cylindrical tissues: experimental evidence for the shielding effect.

PubMed

Feder, Idit; Duadi, Hamootal; Dreifuss, Tamar; Fixler, Dror

2016-10-01

Optical methods for detecting physiological state based on light-tissue interaction are noninvasive, inexpensive, simplistic, and thus very useful. The blood vessels in human tissue are the main cause of light absorbing and scattering. Therefore, the effect of blood vessels on light-tissue interactions is essential for optically detecting physiological tissue state, such as oxygen saturation, blood perfusion and blood pressure. We have previously suggested a new theoretical and experimental method for measuring the full scattering profile, which is the angular distribution of light intensity, of cylindrical tissues. In this work we will present experimental measurements of the full scattering profile of heterogenic cylindrical phantoms that include blood vessels. We show, for the first time that the vessel diameter influences the full scattering profile, and found higher reflection intensity for larger vessel diameters accordance to the shielding effect. For an increase of 60% in the vessel diameter the light intensity in the full scattering profile above 90° is between 9% to 40% higher, depending on the angle. By these results we claim that during respiration, when the blood-vessel diameter changes, it is essential to consider the blood-vessel diameter distribution in order to determine the optical path in tissues. A CT scan of the measured silicon-based phantoms. The phantoms contain the same blood volume in different blood-vessel diameters. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stress Analysis of Bolted, Segmented Cylindrical Shells Exhibiting Flange Mating-Surface Waviness

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.; Phillips, Dawn R.; Raju, Ivatury S.

2009-01-01

Bolted, segmented cylindrical shells are a common structural component in many engineering systems especially for aerospace launch vehicles. Segmented shells are often needed due to limitations of manufacturing capabilities or transportation issues related to very long, large-diameter cylindrical shells. These cylindrical shells typically have a flange or ring welded to opposite ends so that shell segments can be mated together and bolted to form a larger structural system. As the diameter of these shells increases, maintaining strict fabrication tolerances for the flanges to be flat and parallel on a welded structure is an extreme challenge. Local fit-up stresses develop in the structure due to flange mating-surface mismatch (flange waviness). These local stresses need to be considered when predicting a critical initial flaw size. Flange waviness is one contributor to the fit-up stress state. The present paper describes the modeling and analysis effort to simulate fit-up stresses due to flange waviness in a typical bolted, segmented cylindrical shell. Results from parametric studies are presented for various flange mating-surface waviness distributions and amplitudes.

Preparation and magnetic properties of cylindrical NiFe films and antidot arrays.

PubMed

Sanz, R; Navas, D; Vazquez, M; Hernández-Vélez, M; Ross, C A

2010-10-01

Continuous NiFe (Permalloy) cylindrical films and arrays of cylindrical NiFe antidots 7 nm thick have been prepared by sputtering onto cylindrical aluminum wires and onto wires anodized to form a porous anodic alumina layer. The antidots are arranged in a close-packed pattern determined by the hexagonal pore arrangement in the porous alumina, with period 103 nm and diameter 42 nm. Hysteresis loops were measured at different angles with respect to the cylinder axis and indicate an easy plane normal to the radius of the wire. The antidots enhance the coercivity compared to the continuous cylindrical film.

Estimation of Flow Channel Parameters for Flowing Gas Mixed with Air in Atmospheric-pressure Plasma Jets

NASA Astrophysics Data System (ADS)

Yambe, Kiyoyuki; Saito, Hidetoshi

2017-12-01

When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working gas flows into the atmosphere from the inside of a quartz tube, the gas mixes with air. The molar ratio of the working gas and air is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.

Characterization of the exradin W1 plastic scintillation detector for small field applications in proton therapy.

PubMed

Hoehr, C; Lindsay, C; Beaudry, J; Penner, C; Strgar, V; Lee, R; Duzenli, C

2018-05-04

Accurate dosimetry in small field proton therapy is challenging, particularly for applications such as ocular therapy, and suitable detectors for this purpose are sought. The Exradin W1 plastic scintillating fibre detector is known to out-perform most other detectors for determining relative dose factors for small megavoltage photon beams used in radiotherapy but its potential in small proton beams has been relatively unexplored in the literature. The 1 mm diameter cylindrical geometry and near water equivalence of the W1 makes it an attractive alternative to other detectors. This study examines the dosimetric performance of the W1 in a 74 MeV proton therapy beam with particular focus on detector response characteristics relevant to relative dose measurement in small fields suitable for ocular therapy. Quenching of the scintillation signal is characterized and demonstrated not to impede relative dose measurements at a fixed depth. The background cable-only (Čerenkov and radio-fluorescence) signal is 4 orders of magnitude less than the scintillation signal, greatly simplifying relative dose measurements. Comparison with other detectors and Monte Carlo simulations indicate that the W1 is useful for measuring relative dose factors for field sizes down to 5 mm diameter and shallow spread out Bragg peaks down to 6 mm in depth.

Characterization of the exradin W1 plastic scintillation detector for small field applications in proton therapy

NASA Astrophysics Data System (ADS)

Hoehr, C.; Lindsay, C.; Beaudry, J.; Penner, C.; Strgar, V.; Lee, R.; Duzenli, C.

2018-05-01

Accurate dosimetry in small field proton therapy is challenging, particularly for applications such as ocular therapy, and suitable detectors for this purpose are sought. The Exradin W1 plastic scintillating fibre detector is known to out-perform most other detectors for determining relative dose factors for small megavoltage photon beams used in radiotherapy but its potential in small proton beams has been relatively unexplored in the literature. The 1 mm diameter cylindrical geometry and near water equivalence of the W1 makes it an attractive alternative to other detectors. This study examines the dosimetric performance of the W1 in a 74 MeV proton therapy beam with particular focus on detector response characteristics relevant to relative dose measurement in small fields suitable for ocular therapy. Quenching of the scintillation signal is characterized and demonstrated not to impede relative dose measurements at a fixed depth. The background cable-only (Čerenkov and radio-fluorescence) signal is 4 orders of magnitude less than the scintillation signal, greatly simplifying relative dose measurements. Comparison with other detectors and Monte Carlo simulations indicate that the W1 is useful for measuring relative dose factors for field sizes down to 5 mm diameter and shallow spread out Bragg peaks down to 6 mm in depth.

Inward electrostatic precipitation of interplanetary particles

NASA Technical Reports Server (NTRS)

Rulison, Aaron J.; Flagan, Richard C.; Ahrens, Thomas J.

1993-01-01

An inward precipitator collects particles initially dispersed in a gas throughout either a cylindrical or spherical chamber onto a small central planchet. The instrument is effective for particle diameters greater than about 1 micron. One use is the collection of interplanetary dust particles (IDPs) which are stopped in a noble gas (xenon) by drag and ablation after perforating the wall of a thin-walled spacecraft-mounted chamber. First, the particles are positively charged for several seconds by the corona production of positive xenon ions from inward facing needles placed on the chamber wall. Then an electric field causes the particles to migrate toward the center of the instrument and onto the planchet. The collection time (on the order of hours for a 1 m radius spherical chamber) is greatly reduced by the use of optimally located screens which reapportion the electric field. Some of the electric field lines terminate on the wires of the screens so a fraction of the total number of particles in the chamber is lost. The operation of the instrument is demonstrated by experiments which show the migration of carbon soot particles with radius of approximately 1 micron in a 5 cm diameter cylindrical chamber with a single field enhancing screen toward a 3.2 mm central collection rod.

Alining Large Cylinders for Welding

NASA Technical Reports Server (NTRS)

Ehl, J. H.

1985-01-01

Special tooling alines and holds internally-stiffened large-diameter cylindrical parts for welding. Alinement brackets attached to strengthening fins on insides of cylindrical tank sections. Jackscrews on brackets raised or lowered to eliminate mismatches between adjacent sections. Tooling substantially reduces costs while allowing more precise control and improved quality.

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.

Transition Induced by a Streamwise Array of Roughness Elements on a Supersonic Flat Plate

NASA Technical Reports Server (NTRS)

Chou, Amanda; Kegerise, Michael A.

2017-01-01

Roughness is unavoidable on practical high-speed vehicles, so it is critical to determine its impact on boundary layer transition. The flow field downstream of a streamwise array of cylindrical roughness elements is probed with hot-wire anemometry in this experiment. Mean flow distortion is examined in several measurement planes in the wake of the cylindrical roughness using the streak strength profiles and contour plots of the mass flux and total temperature. The roughness element heights and spacings were varied and their instability modes were examined. Cylindrical roughness elements approximately 140 micron tall produce an odd instability mode that grows weakly with downstream distance in the measurement range of this experiment. Cylindrical roughness elements approximately 280 micron tall produce an even instability mode that grows, becomes nonlinear, and then breaks down. Transition onset remains constant relative to the most downstream roughness in the streamwise array when the 280 micron roughness elements are spaced 2 diameters apart. Transition onset occurs at an earlier upstream location relative to the most downstream roughness in the streamwise array when the roughness elements are spaced 4 diameters appear to recover before the next downstream roughness element, so the location of transition shifts with the location of the most downstream roughness element in the array. When the rough- apart. The wake behind roughness elements spaced 2 diameters apart do not ness elements are spaced 4 diameters apart, the flow behind the first roughness element has enough space to recover before feeding into the second roughness element, and thus, moves transition forward.

Detection efficiency vs. cathode and anode separation in cylindrical vacuum photodiodes used for measuring x-rays from plasma focus device.

PubMed

Borthakur, T K; Talukdar, N; Neog, N K; Rao, C V S; Shyam, A

2011-10-01

A qualitative study on the performance of cylindrical vacuum photodiodes (VPDs) for x-ray detection in plasma focus device has been carried out. Various parameters of VPD such as electrode's diameter, electrode's separation, and its sensitivity are experimentally tested in plasma focus environment. For the first time it is found experimentally that the electrode-separation in the lateral direction of the two coaxial electrodes of cylindrical VPD also plays an important role to increase the efficiency of the detector. The efficiency is found to be highest for the detector with smaller cathode-anode lateral gap (1.5 mm) with smaller photo cathode diameter (10 mm). A comparison between our VPD with PIN (BPX-65) diode as an x-ray detector has also been made.

Pipe support for use in a nuclear system

DOEpatents

Pollono, Louis P.; Mello, Raymond M.

1977-01-01

A pipe support for high temperature, thin-walled vertical piping runs used in a nuclear system. A cylindrical pipe transition member, having the same inside diameter as the thin-walled piping, replaces a portion of the piping where support is desired. The outside diameter of the pipe transition member varies axially along its vertical dimension. For a section of the axial length adjacent the upper and lower terminations of the pipe transition member, the outside diameter is the same as the outside diameter of the thin-walled piping to which it is affixed. Intermediate of the termination sections, the outside diameter increases from the top of the member to the bottom. Adjacent the lower termination section, the diameter abruptly becomes the same as the piping. Thus, the cylindrical transition member is formed to have a generally triangular shaped cross-section along the axial dimension. Load-bearing insulation is installed next to the periphery of the member and is kept in place by an outer ring clamp. The outer ring clamp is connected to pipe hangers, which provide the desired support for the vertical thin-walled piping runs.

Gate simulation of Compton Ar-Xe gamma-camera for radionuclide imaging in nuclear medicine

NASA Astrophysics Data System (ADS)

Dubov, L. Yu; Belyaev, V. N.; Berdnikova, A. K.; Bolozdynia, A. I.; Akmalova, Yu A.; Shtotsky, Yu V.

2017-01-01

Computer simulations of cylindrical Compton Ar-Xe gamma camera are described in the current report. Detection efficiency of cylindrical Ar-Xe Compton camera with internal diameter of 40 cm is estimated as1-3%that is 10-100 times higher than collimated Anger’s camera. It is shown that cylindrical Compton camera can image Tc-99m radiotracer distribution with uniform spatial resolution of 20 mm through the whole field of view.

Heat transfer to small horizontal cylinders immersed in a fluidized bed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, J.; Koundakjian, P.; Naylor, D.

2006-10-15

Heat transfer to horizontal cylinders immersed in fluidized beds has been extensively studied, but mainly in the context of heat transfer to boiler tubes in coal-fired beds. As a result, most correlations in the literature have been derived for cylinders of 25-50 mm diameter in vigorously fluidizing beds. In recent years, fluidized bed heat treating furnaces fired by natural gas have become increasingly popular, particularly in the steel wire manufacturing industry. These fluidized beds typically operate at relatively low fluidizing rates and with small diameter wires (1-6 mm). Nusselt number correlations developed based on boiler tube studies do not extrapolatemore » down to these small size ranges and low fluidizing rates. In order to obtain reliable Nusselt number data for these size ranges, an experimental investigation has been undertaken using two heat treating fluidized beds; one a pilot-scale industrial unit and the other a lab-scale (300 mm diameter) unit. Heat transfer measurements were obtained using resistively heated cylindrical samples ranging from 1.3 to 9.5 mm in diameter at fluidizing rates ranging from approximately 0.5 x G{sub mf} (packed bed condition) to over 10 x G{sub mf} using aluminum oxide sand particles ranging from d{sub p}=145-330 {mu}m (50-90 grit). It has been found that for all cylinder sizes tested, the Nusselt number reaches a maximum near 2 x G{sub mf}, then remains relatively steady ({+-}5-10%) to the maximum fluidizing rate tested, typically 8-12xG{sub mf}. A correlation for maximum Nusselt number is developed.« less

Recirculation cells for granular flow in cylindrical rotating tumblers

NASA Astrophysics Data System (ADS)

D'Ortona, Umberto; Thomas, Nathalie; Lueptow, Richard M.

2018-05-01

To better understand the velocity field and flowing layer structure, we have performed a detailed discrete element method study of the flow of monodisperse particles in a partially filled three-dimensional cylindrical rotating tumblers. Similar to what occurs near the poles in spherical and conical tumblers, recirculation cells (secondary flows) develop near the flat endwalls of a cylindrical tumbler in which particles near the surface drift axially toward the endwall, while particles deeper in the flowing layer drift axially toward the midlength of the tumbler. Another recirculation cell with the opposite sense develops next to each endwall recirculation cell, extending to the midlength of the tumbler. For a long enough tumbler, each endwall cell is about one quarter of the tumbler diameter in length. Endwall cells are insensitive to tumbler length and relatively insensitive to rotation speed (so long as the flowing layer remains flat and continuously flowing) or fill level (from 25% to 50% full). However, for shorter tumblers (0.5 to 1.0 length/diameter aspect ratio) the endwall cell size does not change much, while center cells reduce their size and eventually disappear for the shortest tumblers. For longer tumblers (length/diameter aspect ratio larger than 2), a stagnation zone appears in between the central cells. These results provide insight into the mixing of monodisperse particles in rotating cylindrical tumblers as well as the frictional effects of the tumbler endwalls.

Thrust and pumping characteristics of cylindrical ejectors using afterburning turbojet gas generator

NASA Technical Reports Server (NTRS)

Samanich, N. E.; Huntley, S. C.

1969-01-01

Static tests of cylindrical ejectors having ejector to primary diameter ratios from 1.1 to 1.6 and ejector length to primary nozzle diameter ratios from 0.9 to 2.1 are reported. Power setting of the J85-13 turbojet engine was varied from part power to maximum afterburning. Corrected secondary weight flow ratio was varied from 0.02 to 0.08 over a range of exhaust nozzle pressure ratios from 2.0 to 9.0. Secondary flow temperature rise and pressure drop characteristics through the nacelle secondary flow passage were also obtained.

Operating characteristics of tube-current-modulation techniques when scanning simple-shaped phantoms

NASA Astrophysics Data System (ADS)

Matsubara, Kosuke; Koshida, Kichiro; Lin, Pei-Jan Paul; Fukuda, Atsushi

2015-07-01

Our objective was to investigate the operating characteristics of tube current modulation (TCM) in computed tomography (CT) when scanning two types of simple-shaped phantoms. A tissueequivalent elliptical phantom and a homogeneous cylindrical step phantom comprising 16-, 24-, and 32-cm-diameter polymethyl methacrylate (PMMA) phantoms were scanned by using an automatic exposure control system with longitudinal (z-) and angular-longitudinal (xyz-) TCM and with a fixed tube current. The axial dose distribution throughout the elliptical phantom and the longitudinal dose distribution at the center of the cylindrical step phantom were measured by using a solid-state detector. Image noise was quantitatively measured at eight regions in the elliptical phantom and at 90 central regions in contiguous images over the full z extent of the cylindrical step phantom. The mean absorbed doses and the standard deviations in the elliptical phantom with z- and xyz-TCM were 12.3' 3.7 and 11.3' 3.5 mGy, respectively. When TCM was activated, some differences were observed in the absorbed doses of the left and the right measurement points. The average image noises in Hounsfield units (HU) and the standard deviations were 15.2' 2.4 and 15.9' 2.4 HU when using z- and xyz-TCM, respectively. With respect to the cylindrical step phantom under z-TCM, there were sudden decreases followed by increases in image noise at the interfaces with the 24- and 16-cm-diameter phantoms. The image noise of the 24-cm-diameter phantom was, relatively speaking, higher than those of the 16- and 32-cm-diameter phantoms. The simple-shaped phantoms used in this study can be employed to investigate the operating characteristics of automatic exposure control systems when specialized phantoms designed for that purpose are not available.

Effect of implant macro-design on primary stability: A prospective clinical study

PubMed Central

Lozano-Carrascal, Naroa; Salomó-Coll, Oscar; Gilabert-Cerdà, Marta; Farré-Pagés, Nuria; Hernández-Alfaro, Federico

2016-01-01

Background Implant restorations have become a high predictable treatment option. Several caracteristics such as surgical technique and implant design can influence the treatment outcomes. The aim of the present study was to evaluate the influence of implant macro-design on primary stability measured with resonance frequency analysis (RFA) and insertion torque (IT). Material and Methods A total of 47 implants divided in two groups: Test group (TI): 22 Tapered MIS® Seven implants; Control group (CI): 25 cylindrical Astra® Osseospeed implants. All implants were inserted following the manufacturers’ standard protocols. Implant primary stability was measured at the moment of implant placement by registering insertion torque values (ITv) and ISQ values by means of Osstell™ Mentor (ISQv) (Integration Diagnostic Ltd., Goteborg, Sweden). Results In the mandible, mean ISQv for tapered implants (TI) was 71.67±5.16 and for cylindrical implants (CI) 57.15±4.83 (p=0.01). Mean insertion torque was 46.67±6.85 Ncm for TI and 35.77±6.72 Ncm for CI (p=0.01). In the maxilla, mean ISQ was 67.2±4.42 for tapered implants and 49.17±15.30 for cylindrical implants (p=0.01). Mean insertion torque for TI was 41.5±6.26 Ncm and for CI 39.17±6.34 Ncm (p>0.05). For tapered implants, no correlation could be found between implant diameter and primary stability. But for cylindrical implants there was a statistically significant correlation between implant diameter and primary stability: ITv (p=0.03); ISQv (p=0.04). Conclusions Within the limits of the present study, tapered shaped implants achieve higher primary stability measured through ISQ and insertion torque values. Moreover, for cylindrical implants positive correlation has been established between implant diameter and primary stability. Key words:Primary stability, tapered, cylindrical, conical, implant macro-design. PMID:26827067

Growth of modern branched columnar stromatolites in Lake Joyce, Antarctica.

PubMed

Mackey, T J; Sumner, D Y; Hawes, I; Jungblut, A D; Andersen, D T

2015-07-01

Modern decimeter-scale columnar stromatolites from Lake Joyce, Antarctica, show a change in branching pattern during a period of lake level rise. Branching patterns correspond to a change in cyanobacterial community composition as preserved in authigenic calcite crystals. The transition in stromatolite morphology is preserved by mineralized layers that contain microfossils and cylindrical molds of cyanobacterial filaments. The molds are composed of two populations with different diameters. Large diameter molds (>2.8 μm) are abundant in calcite forming the oldest stromatolite layers, but are absent from younger layers. In contrast, <2.3 μm diameter molds are common in all stromatolites layers. Loss of large diameter molds corresponds to the transition from smooth-sided stromatolitic columns to branched and irregular columns. Mold diameters are similar to trichome diameters of the four most abundant living cyanobacteria morphotypes in Lake Joyce: Phormidium autumnale morphotypes have trichome diameters >3.5 μm, whereas Leptolyngbya antarctica, L. fragilis, and Pseudanabaena frigida morphotypes have diameters <2.3 μm. P. autumnale morphotypes were only common in mats at <12 m depth. Mats containing abundant P. autumnale morphotypes were smooth, whereas mats with few P. autumnale morphotypes contained small peaks and protruding bundles of filaments, suggesting that the absence of P. autumnale morphotypes allowed small-scale topography to develop on mats. Comparisons of living filaments and mold diameters suggest that P. autumnale morphotypes were present early in stromatolite growth, but disappeared from the community through time. We hypothesize that the mat-smoothing behavior of P. autumnale morphotypes inhibited nucleation of stromatolite branches. When P. autumnale morphotypes were excluded from the community, potentially reflecting a rise in lake level, short-wavelength roughness provided nuclei for stromatolite branches. This growth history provides a conceptual model for initiation of branched stromatolite growth resulting from a change in microbial community composition. © 2015 John Wiley & Sons Ltd.

Effect of implant macro-design on primary stability: A prospective clinical study.

PubMed

Lozano-Carrascal, Naroa; Salomó-Coll, Oscar; Gilabert-Cerdà, Marta; Farré-Pagés, Nuria; Gargallo-Albiol, Jordi; Hernández-Alfaro, Federico

2016-03-01

Implant restorations have become a high predictable treatment option. Several caracteristics such as surgical technique and implant design can influence the treatment outcomes. The aim of the present study was to evaluate the influence of implant macro-design on primary stability measured with resonance frequency analysis (RFA) and insertion torque (IT). Material and Mehods: A total of 47 implants divided in two groups: Test group (TI): 22 Tapered MIS® Seven implants; Control group (CI): 25 cylindrical Astra® Osseospeed implants. All implants were inserted following the manufacturers' standard protocols. Implant primary stability was measured at the moment of implant placement by registering insertion torque values (ITv) and ISQ values by means of Osstell™ Mentor (ISQv) (Integration Diagnostic Ltd., Goteborg, Sweden). In the mandible, mean ISQv for tapered implants (TI) was 71.67±5.16 and for cylindrical implants (CI) 57.15±4.83 (p=0.01). Mean insertion torque was 46.67±6.85 Ncm for TI and 35.77±6.72 Ncm for CI (p=0.01). In the maxilla, mean ISQ was 67.2±4.42 for tapered implants and 49.17±15.30 for cylindrical implants (p=0.01). Mean insertion torque for TI was 41.5±6.26 Ncm and for CI 39.17±6.34 Ncm (p>0.05). For tapered implants, no correlation could be found between implant diameter and primary stability. But for cylindrical implants there was a statistically significant correlation between implant diameter and primary stability: ITv (p=0.03); ISQv (p=0.04). Within the limits of the present study, tapered shaped implants achieve higher primary stability measured through ISQ and insertion torque values. Moreover, for cylindrical implants positive correlation has been established between implant diameter and primary stability.

Macromolecular shape and interactions in layer-by-layer assemblies within cylindrical nanopores.

PubMed

Lazzara, Thomas D; Lau, K H Aaron; Knoll, Wolfgang; Janshoff, Andreas; Steinem, Claudia

2012-01-01

Layer-by-layer (LbL) deposition of polyelectrolytes and proteins within the cylindrical nanopores of anodic aluminum oxide (AAO) membranes was studied by optical waveguide spectroscopy (OWS). AAO has aligned cylindrical, nonintersecting pores with a defined pore diameter d(0) and functions as a planar optical waveguide so as to monitor, in situ, the LbL process by OWS. The LbL deposition of globular proteins, i.e., avidin and biotinylated bovine serum albumin was compared with that of linear polyelectrolytes (linear-PEs), both species being of similar molecular weight. LbL deposition within the cylindrical AAO geometry for different pore diameters (d(0) = 25-80 nm) for the various macromolecular species, showed that the multilayer film growth was inhibited at different maximum numbers of LbL steps (n(max)). The value of n(max) was greatest for linear-PEs, while proteins had a lower value. The cylindrical pore geometry imposes a physical limit to LbL growth such that n(max) is strongly dependent on the overall internal structure of the LbL film. For all macromolecular species, deposition was inhibited in native AAO, having pores of d(0) = 25-30 nm. Both, OWS and scanning electron microscopy showed that LbL growth in larger AAO pores (d(0) > 25-30 nm) became inhibited when approaching a pore diameter of d(eff,n_max) = 25-35 nm, a similar size to that of native AAO pores, with d(0) = 25-30 nm. For a reasonable estimation of d(eff,n_max), the actual volume occupied by a macromolecular assembly must be taken into consideration. The results clearly show that electrostatic LbL allowed for compact macromolecular layers, whereas proteins formed loosely packed multilayers.

Controlled motion of domain walls in submicron amorphous wires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ţibu, Mihai; Lostun, Mihaela; Rotărescu, Cristian

Results on the control of the domain wall displacement in cylindrical Fe{sub 77.5}Si{sub 7.5}B{sub 15} amorphous glass-coated submicron wires prepared by rapid quenching from the melt are reported. The control methods have relied on conical notches with various depths, up to a few tens of nm, made in the glass coating and in the metallic nucleus using a focused ion beam (FIB) system, and on the use of small nucleation coils at one of the sample ends in order to apply magnetic field pulses aimed to enhance the nucleation of reverse domains. The notch-based method is used for the firstmore » time in the case of cylindrical ultrathin wires. The results show that the most efficient technique of controlling the domain wall motion in this type of samples is the simultaneous use of notches and nucleation coils. Their effect depends on wire diameter, notch depth, its position on the wire length, and characteristics of the applied pulse.« less

Process for sensing defects on a smooth cylindrical interior surface in tubing

DOEpatents

Dutton, G. Wayne

1987-11-17

The cylindrical interior surface of small diameter metal tubing is optically inspected to determine surface roughness by passing a slightly divergent light beam to illuminate the entire interior surface of the tubing. Impingement of the input light beam components on any rough spots on the interior surface generates forward and backward scattered radiation components. The forward scattered components can be measured by blocking direct and specular radiation components exiting the tubing while allowing the forward scattered radiation to travel past the blocking location. Collecting optics are employed to converge the forward scattered radiation onto a photodetector generating a signal indicative of surface roughness. In the back scattered mode, back scattered radiation exiting the tubing through the entrance opening is reflected 90.degree. by a beam splitter towards collecting optics and a photodetector. Alternatively, back scattered radiation can be transmitted through a fiber optic bundle towards the collecting optics. The input light beam can be supplied through a white light fiber optic bundle mounted coaxial with the first bundle.

Process for sensing defects on a smooth cylindrical interior surface in tubing

DOEpatents

Dutton, G.W.

1987-11-17

The cylindrical interior surface of small diameter metal tubing is optically inspected to determine surface roughness by passing a slightly divergent light beam to illuminate the entire interior surface of the tubing. Impingement of the input light beam components on any rough spots on the interior surface generates forward and backward scattered radiation components. The forward scattered components can be measured by blocking direct and specular radiation components exiting the tubing while allowing the forward scattered radiation to travel past the blocking location. Collecting optics are employed to converge the forward scattered radiation onto a photodetector generating a signal indicative of surface roughness. In the back scattered mode, back scattered radiation exiting the tubing through the entrance opening is reflected 90[degree] by a beam splitter towards collecting optics and a photodetector. Alternatively, back scattered radiation can be transmitted through a fiber optic bundle towards the collecting optics. The input light beam can be supplied through a white light fiber optic bundle mounted coaxial with the first bundle. 6 figs.

Process and apparatus for sensing defects on a smooth cylindrical surface in tubing

DOEpatents

Dutton, G.W.

1985-08-05

The cylindrical interior surface of small diameter metal tubing is optically inspected to determine surface roughness by passing a slightly divergent light beam to illuminate the entire interior surface of the tubing. Impingement of the input light beam components on any rough spots on the interior surface generates forward and backward scattered radiation components. The forward scattered components can be measured by blocking direct and specular radiation components exiting the tubing while allowing the forward scattered radiation to travel past the blocking location. Collecting optics are employed to converge the forward scattered radiation onto a photodetector generating a signal indicative of surface roughness. In the back scattered mode, back scattered radiation exiting the tubing through the entrance opening is reflected 90/sup 0/ by a beam splitter towards collecting optics and a photodetector. Alternatively, back scattered radiation can be transmitted through a fiber optic bundle towards the collecting optics. The input light beam can be supplied through a white light fiber optic bundle mounted coaxial with the first bundle.

Preliminary Study of Radioactive Waste Package Made of High-Strength and Ultra Low-Permeability Concrete for Geological Disposal of TRU Wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuo, T.; Kawasaki, T.; Sakamoto, H.

2003-02-27

We have been developing a radioactive waste package made of high-strength and ultra low-permeability concrete (HSULPC) for geological disposal of TRU wastes, which is expected to be much more impervious to water than conventional concrete. In this study, basic data for the HSULPC regarding its the impervious character and the thermodynamics during cement hydration were obtained through water permeability measurements using cold isostatic pressing (CIP) and adiabatic concrete hydration experiments, respectively. Then, a prediction tool to find concrete package construction conditions to avoid thermal cracking was developed, which could deal with coupled calculations of cement hydration, heat transfer, stress, andmore » cracking. The developed tool was applied to HSULPC hydration on a small-scale cylindrical model to examine whether there was any effect on cracking which depended on the ratio of concrete cylinder thickness to its inner diameter. The results were compared to experiments. For concrete with a compressive strength of 200MPa, the water permeability coefficient was 4 x 10{sup 19} m/s. Dependences of activation energy and frequency factor on degree of cement hydration had a sharp peaking due to the nucleation rate-determining step, and a gradual increase region due to the diffusion rate-determining step. From analyses of the small-scale cylindrical model, dependences of the maximum principal stress on the radius were obtained. When the ratio of the concrete thickness to the heater diameter was around 1, the risk of cracking was predicted to be minimized. These numerical predictions from the developed tool were verified by experiments.« less

Echocolor Doppler morpho-functional study of the jugulo-subclavian confluence in chronic cerebro-spinal venous insufficiency and multiple sclerosis patients.

PubMed

Mandolesi, Sandro; d'Alessandro, Aldo; Desogus, Antonello Ignazio; Ciccone, Marco Matteo; Zito, Annapaola; Stammegna, Immacolata; Niglio, Tarcisio; Orsini, Augusto; Mandolesi, Dimitri; d'Alessandro, Alessandro; Revelli, Luca

2017-01-01

The aim of this work is to measure the mean diameter of the confluence jugulo- subclavian, the impact of different types of jugular confluences and the correlation between the types of confluences and the Valsalva maneuver (jugular reflux) in subjects with Chronic Cerebro-Spinal Venous Insufficiency (CCSVI) and Multiple Sclerosis. We investigated by Echo-Color-Doppler (ECD) 103 subjects (67 F 36M) of mean age 45 ± 12 years (a minimum of 22 to a maximum of 79 years, with a median of 44 and a modal value 42 years), mean EDSS of 4.7 and average disease duration of 12 years. The 103 right jugular veins investigated had an average diameter of 8.4 ± 2.4 mm (minimum 4.0, maximum 14.9 mm; median 7.9; modal value 7.6 mm). Three form types were found: 56 cylindrical, 29 conical and 18 funnel. Valsalva maneuver was positive in 30 patients. The 103 left jugular investigated had an average diameter of 8.9 ± 2.4 mm (minimum 2.8, maximum 14.4 mm; median of 8.8; modal value 8.7 mm). The form types were found: 42 cylindrical, 45 conical and 16 funnel. Valsalva maneuver was positive in 30 patients. The mean diameter of the jugular veins was 8.7 mm. Internal jugular veins with cylindrical morphology have a diameter smaller than other forms; this difference is statistically significant. The different morphology of the jugular vein confluence does not increase the possibility of a reflux because the positive Valsalva maneuvers are not statistically significant when compared to the various types. CCSVI, EchoColorDoppler Map, Jugulo-Subclavian Confluence Diameter.

Winding for linear pump

DOEpatents

Kliman, G.B.; Brynsvold, G.V.; Jahns, T.M.

1989-08-22

A winding and method of winding for a submersible linear pump for pumping liquid sodium are disclosed. The pump includes a stator having a central cylindrical duct preferably vertically aligned. The central vertical duct is surrounded by a system of coils in slots. These slots are interleaved with magnetic flux conducting elements, these magnetic flux conducting elements forming a continuous magnetic field conduction path along the stator. The central duct has placed therein a cylindrical magnetic conducting core, this core having a cylindrical diameter less than the diameter of the cylindrical duct. The core once placed to the duct defines a cylindrical interstitial pumping volume of the pump. This cylindrical interstitial pumping volume preferably defines an inlet at the bottom of the pump, and an outlet at the top of the pump. Pump operation occurs by static windings in the outer stator sequentially conveying toroidal fields from the pump inlet at the bottom of the pump to the pump outlet at the top of the pump. The winding apparatus and method of winding disclosed uses multiple slots per pole per phase with parallel winding legs on each phase equal to or less than the number of slots per pole per phase. The slot sequence per pole per phase is chosen to equalize the variations in flux density of the pump sodium as it passes into the pump at the pump inlet with little or no flux and acquires magnetic flux in passage through the pump to the pump outlet. 4 figs.

Winding for linear pump

DOEpatents

Kliman, Gerald B.; Brynsvold, Glen V.; Jahns, Thomas M.

1989-01-01

A winding and method of winding for a submersible linear pump for pumping liquid sodium is disclosed. The pump includes a stator having a central cylindrical duct preferably vertically aligned. The central vertical duct is surrounded by a system of coils in slots. These slots are interleaved with magnetic flux conducting elements, these magnetic flux conducting elements forming a continuous magnetic field conduction path along the stator. The central duct has placed therein a cylindrical magnetic conducting core, this core having a cylindrical diameter less than the diameter of the cylindrical duct. The core once placed to the duct defines a cylindrical interstitial pumping volume of the pump. This cylindrical interstitial pumping volume preferably defines an inlet at the bottom of the pump, and an outlet at the top of the pump. Pump operation occurs by static windings in the outer stator sequentially conveying toroidal fields from the pump inlet at the bottom of the pump to the pump outlet at the top of the pump. The winding apparatus and method of winding disclosed uses multiple slots per pole per phase with parallel winding legs on each phase equal to or less than the number of slots per pole per phase. The slot sequence per pole per phase is chosen to equalize the variations in flux density of the pump sodium as it passes into the pump at the pump inlet with little or no flux and acquires magnetic flux in passage through the pump to the pump outlet.

Multiple scattering by infinitely long cylindrical glass inclusions in a saturated Biot porous medium of glass beads.

PubMed

Trabelsi, W; Franklin, H; Tinel, A

2016-05-01

The resonance spectrum of sets of two to five infinitely long parallel cylindrical glass inclusions in a fluid saturated porous matrix of unconsolidated glass beads is investigated. The ratio of bead diameters to inclusion diameters is 1/5. The far field form functions and the related phase derivatives are calculated by using an exact multiple scattering formalism and by assuming that the porous medium obeys Biot's model. In order to validate this hypothesis, comparisons between theory and experiments are done in the special case of a fast incident wave on a set of two and three inclusions.

Simulation study of poled low-water ionomers with different architectures

NASA Astrophysics Data System (ADS)

Allahyarov, Elshad; Taylor, Philip L.; Löwen, Hartmut

2011-11-01

The role of the ionomer architecture in the formation of ordered structures in poled membranes is investigated by molecular dynamics computer simulations. It is shown that the length of the sidechain Ls controls both the areal density of cylindrical aggregates Nc and the diameter of these cylinders in the poled membrane. The backbone segment length Lb tunes the average diameter Ds of cylindrical clusters and the average number of sulfonates Ns in each cluster. A simple empirical formula is noted for the dependence of the number density of induced rod-like aggregates on the sidechain length Ls within the parameter range considered in this study.

Shear localization and effective wall friction in a wall bounded granular flow

NASA Astrophysics Data System (ADS)

Artoni, Riccardo; Richard, Patrick

2017-06-01

In this work, granular flow rheology is investigated by means of discrete numerical simulations of a torsional, cylindrical shear cell. Firstly, we focus on azimuthal velocity profiles and study the effect of (i) the confining pressure, (ii) the particle-wall friction coefficient, (iii) the rotating velocity of the bottom wall and (iv) the cell diameter. For small cell diameters, azimuthal velocity profiles are nearly auto-similar, i.e. they are almost linear with the radial coordinate. Different strain localization regimes are observed : shear can be localized at the bottom, at the top of the shear cell, or it can be even quite distributed. This behavior originates from the competition between dissipation at the sidewalls and dissipation in the bulk of the system. Then we study the effective friction at the cylindrical wall, and point out the strong link between wall friction, slip and fluctuations of forces and velocities. Even if the system is globally below the sliding threshold, force fluctuations trigger slip events, leading to a nonzero wall slip velocity and an effective wall friction coefficient different from the particle-wall one. A scaling law was found linking slip velocity, granular temperature in the main flow direction and effective friction. Our results suggest that fluctuations are an important ingredient for theories aiming to capture the interface rheology of granular materials.

Effect of Stepwise Pressure Change on Porosity Evolution during Directional Solidification in Small Cylindrical Channels

NASA Technical Reports Server (NTRS)

Grugel, R.N.; Lee, C.P.; Cox, M.C.; Blandford, B.T.; Anilkumar, A.V.

2008-01-01

Controlled directional solidification experiments were performed in capillary channels, using nitrogen-saturated succinonitrile, to examine the effect of an in-situ stepwise processing pressure increase on an isolated pore evolution. Two experiments were performed using different processing pressure input profiles. The results indicate that a processing pressure increase has a transient effect on pore growth geometry characterized by an initial phase of decreasing pore diameter, followed by a recovery phase of increasing pore diameter. The experimental results also show that processing pressure can be used as a control parameter to either increase or terminate porosity formation. A theoretical model is introduced which indicates that the pore formation process is limited by the diffusion of solute-gas through the melt, and that the observed response toa pressure increase is attributed to the re-equilibration of solute concentration in the melt associated with the increased melt pressure.

Comparisons of Force Measurement Methods for DBD Plasma Actuators in Quiescent Air

NASA Technical Reports Server (NTRS)

Hoskinson, Alan R.; Hershkowitz, Noah; Ashpis, David E.

2009-01-01

We have performed measurements of the force induced by both single (one electrode insulated) and double (both electrodes insulated) dielectric barrier discharge plasma actuators in quiescent air. We have shown that, for single barrier actuators with cylindrical exposed electrodes, as the electrode diameter decrease the force efficiencies increase much faster than a previously reported linear trend. This behavior has been experimentally verified using two different measurement techniques: stagnation probe measurements of the induced flow velocity and direct measurement of the force using an electronic balance. Actuators with rectangular cross-section exposed electrodes do not show the same rapid increase at small thicknesses. We have also shown that the induced force is independent of the material used for the exposed electrode. The same techniques have shown that the induced force of a double barrier actuator increases with decreasing narrow electrode diameter.

Magnetic properties of cylindrical diameter modulated Ni80Fe20 nanowires: interaction and coercive fields

NASA Astrophysics Data System (ADS)

Salem, Mohamed Shaker; Sergelius, Philip; Corona, Rosa M.; Escrig, Juan; Görlitz, Detlef; Nielsch, Kornelius

2013-04-01

Magnetic properties of cylindrical Ni80Fe20 nanowires with modulated diameters are investigated theoretically as a function of their geometrical parameters and compared with those produced inside the pores of anodic alumina membranes by pulsed electrodeposition. We observe that the Ni80Fe20 nanowires with modulated diameters reverse their magnetization via the nucleation and propagation of a vortex domain wall. The system begins generating vortex domains in the nanowire ends and in the transition region between the two segments to minimize magnetostatic energy generated by surfaces perpendicular to the initial magnetization of the sample. Besides, we observed an increase of the coercivity for the sample with equal volumes in relation to the sample with equal lengths. Finally, the interaction field is stronger in the case of constant volume segments. These structures could be used to control the motions of magnetic domain walls. In this way, these nanowires with modulated diameters can be an alternative to store information or even perform logic functions.

Measurement of the photoneutron flux density distribution from cylindrical targets

NASA Astrophysics Data System (ADS)

Golovkov, V. M.; Basina, T. N.; Yakovlev, M. R.

1989-09-01

Measurements are performed of the density of photoneutron fluxes from cylindrical targets of2H2O (diameter 64 and height 86 mm), Be (outer diameter 70, inner diameter 40, height 100mm), and238U (diameter 44.5 mm, height 50 mm) under the action of braking radiation from electrons with energies of 4 to 8 MeV in order to determine the effect of target form and orientation relative to the detector upon the recorded photoneutron level. The fluxes were measured by an “all-wave” neutron detector based on an SNM-11 counter in a paraffin retarder at an angle of 90‡ to the axis of the braking radiation beam for various target orientations relative to the detector. Measurement results are compared to calculations. Photoneutron fluxes from heavy water and beryllium targets of the indicated dimensions were also measured for angles of 90, 135, and 167‡. An isotropic nature was noted in the photoneutron fluxes from both targets.

An automated inner dimensional measurement system based on a laser displacement sensor for long-stepped pipes.

PubMed

Zhang, Fumin; Qu, Xinghua; Ouyang, Jianfei

2012-01-01

A novel measurement prototype based on a mobile vehicle that carries a laser scanning sensor is proposed. The prototype is intended for the automated measurement of the interior 3D geometry of large-diameter long-stepped pipes. The laser displacement sensor, which has a small measurement range, is mounted on an extended arm of known length. It is scanned to improve the measurement accuracy for large-sized pipes. A fixing mechanism based on two sections is designed to ensure that the stepped pipe is concentric with the axis of rotation of the system. Data are acquired in a cylindrical coordinate system and fitted in a circle to determine diameter. Systematic errors covering arm length, tilt, and offset errors are analyzed and calibrated. The proposed system is applied to sample parts and the results are discussed to verify its effectiveness. This technique measures a diameter of 600 mm with an uncertainty of 0.02 mm at a 95% confidence probability. A repeatability test is performed to examine precision, which is 1.1 μm. A laser tracker is used to verify the measurement accuracy of the system, which is evaluated as 9 μm within a diameter of 600 mm.

Cylindrical fabric-confined soil structures

NASA Astrophysics Data System (ADS)

Harrison, Richard A.

A cylindrical fabric-soil structural concept for implementation on the moon and Mars which provides many advantages is proposed. The most efficient use of fabric is to fashion it into cylindrical tubes, creating cylindrical fabric-confined soil structures. The length, diameter, and curvature of the tubes will depend on the intended application. The cylindrical hoop forces provide radial confinement while end caps provide axial confinement. One of the ends is designed to allow passage of the soil into the fabric tube before sealing. Transportation requirements are reduced due to the low mass and volume of the fabric. Construction requirements are reduced due to the self-erection capability via the pneumatic exoskeleton. Maintenance requirements are reduced due to the passive nature of the concept. The structure's natural ductility is well suited for any seismic activity.

Heat transfer studies on the liquid droplet radiator

NASA Technical Reports Server (NTRS)

Mattick, A. T.; Nelson, M.

1987-01-01

This paper examines radiation transfer in the droplet sheet of a liquid droplet radiator including non-isotropic scattering by the droplets. Non-isotropic scattering becomes significant for small droplets (diameter less than 0.1 mm) and for low emissivity liquids. For droplets with an emittance of 0.1 and for a droplet sheet optical depth or 5, the radiated power varies by about 12 percent, depending on whether scattering is predominantly forward or backward. An experimental measurement of the power emitted by a cylindrical cloud of heated droplets of silicone fluid is also reported. The measured cloud emissivity correlates, within experimental error, with the analytical model.

The sizing of hamstring grafts for anterior cruciate reconstruction: intra- and inter-observer reliability.

PubMed

Dwyer, Tim; Whelan, Daniel B; Khoshbin, Amir; Wasserstein, David; Dold, Andrew; Chahal, Jaskarndip; Nauth, Aaron; Murnaghan, M Lucas; Ogilvie-Harris, Darrell J; Theodoropoulos, John S

2015-04-01

The objective of this study was to establish the intra- and inter-observer reliability of hamstring graft measurement using cylindrical sizing tubes. Hamstring tendons (gracilis and semitendinosus) were harvested from ten cadavers by a single surgeon and whip stitched together to create ten 4-strand hamstring grafts. Ten sports medicine surgeons and fellows sized each graft independently using either hollow cylindrical sizers or block sizers in 0.5-mm increments—the sizing technique used was applied consistently to each graft. Surgeons moved sequentially from graft to graft and measured each hamstring graft twice. Surgeons were asked to state the measured proximal (femoral) and distal (tibial) diameter of each graft, as well as the diameter of the tibial and femoral tunnels that they would drill if performing an anterior cruciate ligament (ACL) reconstruction using that graft. Reliability was established using intra-class correlation coefficients. Overall, both the inter-observer and intra-observer agreement were >0.9, demonstrating excellent reliability. The inter-observer reliability for drill sizes was also excellent (>0.9). Excellent correlation was seen between cylindrical sizing, and drill sizes (>0.9). Sizing of hamstring grafts by multiple surgeons demonstrated excellent intra-observer and intra-observer reliability, potentially validating clinical studies exploring ACL reconstruction outcomes by hamstring graft diameter when standard techniques are used. III.

The incidence and effect of noncylindrical neck morphology on outcomes after endovascular aortic aneurysm repair in the Global Registry for Endovascular Aortic Treatment.

PubMed

Shutze, William; Suominem, Velipekka; Jordan, William; Cao, Piergiorgio; Oweida, Steven; Milner, Ross

2018-05-23

The Gore Global Registry for Endovascular Aortic Treatment (GREAT) was designed to evaluate real-world outcomes after treatment with Gore aortic endografts used in a real-world, global setting. We retrospectively analyzed the GREAT data to evaluate the incidence and effects of noncylindrical neck anatomy in patients undergoing endovascular aortic aneurysm repair. The present analysis included patients with data in the GREAT who had been treated with the EXCLUDER endograft from August 2010 to October 2016. A noncylindrical neck was defined when the proximal aortic landing zone diameter had changed ≥2 mm over the first 15 mm of the proximal landing zone, indicating a tapered, conical, or hourglass morphology. Cox multivariate regression analyses were performed for any reintervention (including reinterventions on aortic branch vessels), device-related reinterventions, and reintervention specifically for endoleak. Independent binary (cylindrical vs noncylindrical necks) and continuous (percentage of neck diameter change) variables were assessed. The abdominal aortic aneurysm (AAA) diameter, proximal neck length, maximal infrarenal neck angle, gender, and use of aortic extender cuffs were also assessed. Of 3077 GREAT patients with available proximal aortic landing zone diameter measurements available, 1765 were found to have cylindrical necks and 1312 had noncylindrical necks. The noncylindrical neck cohort had a significantly greater proportion of women (17.4% vs 12.6%; P < .001) and more severe infrarenal angulation (33.8° vs 28.4°; P < .001). A total 14.7% of noncylindrical neck patients and 11.2% cylindrical neck patients underwent implantation outside of the EXCLUDER instructions for use regarding the anatomic inclusion criteria (P = .004). The procedural characteristics were similar between the two cohorts; however, noncylindrical neck patients required significantly more aortic extender cuffs (P = .004). The average follow-up was 21.2 ± 17.5 months and 17.8 ± 15.8 months for the cylindrical and noncylindrical cohorts, respectively (P < .001). The Cox multivariate regression models demonstrated female gender and maximum AAA diameter were significant risk factors for subsequent reintervention (overall, device-related, and endoleak-specific). Women were 2.2 times as likely to require device-related intervention during the follow-up period compared with men (P < .001). Neck shape morphology was not a significant predictor, except for device-related intervention, for which cylindrical necks (binary definition) resulted in a slightly elevated risk (1.5 times; P = .03). Noncylindrical neck morphology was more common in women and was associated with an increased use of aortic extender cuffs but did not increase the risk of intervention. Female gender and AAA diameter were associated with an increased need for reintervention. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Stretch-induced contraction in pulmonary arteries.

PubMed

Kulik, T J; Evans, J N; Gamble, W J

1988-12-01

Stretch stimulates contraction of systemic blood vessels, but the response has not been described in pulmonary vessels. To determine whether pulmonary arteries contract when stretched, isolated cylindrical segments of pulmonary arteries were suspended between two parallel wires, stretched, and the active force was generated in response to stretch measured. Eighty-nine percent of segments from small (in situ diameter less than 1,000 microns) feline pulmonary arteries contracted when stretched, and in 65% of these the magnitude of stretch was related to the magnitude of contraction. Large (in situ diameter greater than or equal to 1,000 microns) feline pulmonary arteries did not contract with stretch. Multiple, rapidly repeated stretches resulted in a diminution of active force development. Stretch-induced contraction required external Ca2+ and was abolished by diltiazem (10 microns), but it was not affected by phenoxybenzamine, phentolamine, diethylcarbamazine, or mechanical removal of endothelium. Indomethacin blunted but did not abolish stretch-induced contraction, an effect that may have been nonspecific. This study suggests that stretch can act, probably directly, on smooth muscle in small feline pulmonary arteries to elicit contraction and that it may be a determinant of pulmonary vascular tone. In addition, feline pulmonary arteries are suitable for the in vitro study of stretch-induced contraction.

Development of a radial-torsional vibration hybrid type ultrasonic motor with a hollow and short cylindrical structure.

PubMed

Wang, Jian; Guo, Jifeng

2009-05-01

A longitudinal-torsional hybrid-type ultrasonic motor has larger torque and lower revolution speed compared with other kinds of ultrasonic motors. It drives devices directly and precisely, so it is adaptable to many fields, especially aeronautics and astronautics, as a servo actuator. Due to the different sound propagation speeds of longitudinal and torsional vibrations in the stator, it is difficult to match resonant frequencies of longitudinal and torsional vibrations. In this paper, a new radial-torsional vibration hybrid-type ultrasonic motor is put forward, which utilizes longitudinal vibration derived from radial vibration by the Poisson effect. The short, hollow cylindrical structure easily makes resonant frequencies of first-order radial and torsional vibrations into degeneracy. First, the new structure of the motor is presented. Second, the principle of matching the resonant frequencies is developed, and the motor geometry is optimized by ANSYS software. Finally, a 60-mm diameter prototype is fabricated, which performs well. The no-load velocity and maximum torque are 25 r/min and 5 N x m, respectively. This kind of motor is small, light, and noiseless.

Microcalcification detectability using a bench-top prototype photon-counting breast CT based on a Si strip detector.

PubMed

Cho, Hyo-Min; Ding, Huanjun; Barber, William C; Iwanczyk, Jan S; Molloi, Sabee

2015-07-01

To investigate the feasibility of detecting breast microcalcification (μCa) with a dedicated breast computed tomography (CT) system based on energy-resolved photon-counting silicon (Si) strip detectors. The proposed photon-counting breast CT system and a bench-top prototype photon-counting breast CT system were simulated using a simulation package written in matlab to determine the smallest detectable μCa. A 14 cm diameter cylindrical phantom made of breast tissue with 20% glandularity was used to simulate an average-sized breast. Five different size groups of calcium carbonate grains, from 100 to 180 μm in diameter, were simulated inside of the cylindrical phantom. The images were acquired with a mean glandular dose (MGD) in the range of 0.7-8 mGy. A total of 400 images was used to perform a reader study. Another simulation study was performed using a 1.6 cm diameter cylindrical phantom to validate the experimental results from a bench-top prototype breast CT system. In the experimental study, a bench-top prototype CT system was constructed using a tungsten anode x-ray source and a single line 256-pixels Si strip photon-counting detector with a pixel pitch of 100 μm. Calcium carbonate grains, with diameter in the range of 105-215 μm, were embedded in a cylindrical plastic resin phantom to simulate μCas. The physical phantoms were imaged at 65 kVp with an entrance exposure in the range of 0.6-8 mGy. A total of 500 images was used to perform another reader study. The images were displayed in random order to three blinded observers, who were asked to give a 4-point confidence rating on each image regarding the presence of μCa. The μCa detectability for each image was evaluated by using the average area under the receiver operating characteristic curve (AUC) across the readers. The simulation results using a 14 cm diameter breast phantom showed that the proposed photon-counting breast CT system can achieve high detection accuracy with an average AUC greater than 0.89 ± 0.07 for μCas larger than 120 μm in diameter at a MGD of 3 mGy. The experimental results using a 1.6 cm diameter breast phantom showed that the prototype system can achieve an average AUC greater than 0.98 ± 0.01 for μCas larger than 140 μm in diameter using an entrance exposure of 1.2 mGy. The proposed photon-counting breast CT system based on a Si strip detector can potentially offer superior image quality to detect μCa with a lower dose level than a standard two-view mammography.

An Automated Inner Dimensional Measurement System Based on a Laser Displacement Sensor for Long-Stepped Pipes

PubMed Central

Zhang, Fumin; Qu, Xinghua; Ouyang, Jianfei

2012-01-01

A novel measurement prototype based on a mobile vehicle that carries a laser scanning sensor is proposed. The prototype is intended for the automated measurement of the interior 3D geometry of large-diameter long-stepped pipes. The laser displacement sensor, which has a small measurement range, is mounted on an extended arm of known length. It is scanned to improve the measurement accuracy for large-sized pipes. A fixing mechanism based on two sections is designed to ensure that the stepped pipe is concentric with the axis of rotation of the system. Data are acquired in a cylindrical coordinate system and fitted in a circle to determine diameter. Systematic errors covering arm length, tilt, and offset errors are analyzed and calibrated. The proposed system is applied to sample parts and the results are discussed to verify its effectiveness. This technique measures a diameter of 600 mm with an uncertainty of 0.02 mm at a 95% confidence probability. A repeatability test is performed to examine precision, which is 1.1 μm. A laser tracker is used to verify the measurement accuracy of the system, which is evaluated as 9 μm within a diameter of 600 mm. PMID:22778615

Scale interaction and arrangement in a turbulent boundary layer perturbed by a wall-mounted cylindrical element

NASA Astrophysics Data System (ADS)

Tang, Zhanqi; Jiang, Nan

2018-05-01

This study reports the modifications of scale interaction and arrangement in a turbulent boundary layer perturbed by a wall-mounted circular cylinder. Hot-wire measurements were executed at multiple streamwise and wall-normal wise locations downstream of the cylindrical element. The streamwise fluctuating signals were decomposed into large-, small-, and dissipative-scale signatures by corresponding cutoff filters. The scale interaction under the cylindrical perturbation was elaborated by comparing the small- and dissipative-scale amplitude/frequency modulation effects downstream of the cylinder element with the results observed in the unperturbed case. It was obtained that the large-scale fluctuations perform a stronger amplitude modulation on both the small and dissipative scales in the near-wall region. At the wall-normal positions of the cylinder height, the small-scale amplitude modulation coefficients are redistributed by the cylinder wake. The similar observation was noted in small-scale frequency modulation; however, the dissipative-scale frequency modulation seems to be independent of the cylindrical perturbation. The phase-relationship observation indicated that the cylindrical perturbation shortens the time shifts between both the small- and dissipative-scale variations (amplitude and frequency) and large-scale fluctuations. Then, the integral time scale dependence of the phase-relationship between the small/dissipative scales and large scales was also discussed. Furthermore, the discrepancy of small- and dissipative-scale time shifts relative to the large-scale motions was examined, which indicates that the small-scale amplitude/frequency leads the dissipative scales.

Ionization assisted self-guiding of femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Morozov, A.; Goltsov, A.; Chen, Q.; Scully, M.; Suckewer, S.

2018-05-01

We propose a new mechanism for the self-guiding of ultra-intense sub-picosecond laser pulses in gaseous media. It can be realized via optical field ionization by a laser pulse as it propagates inside an expanding cylindrical shock wave launched into ambient gas by a decayed plasma filament. In experiments, the filament was created in a hydrogen jet by a low energy femtosecond laser pre-pulse line focused with axicon lens. We demonstrated ionization-assisted guiding in structures with diameter as small as 14 μm and up to 3.5 mm long. The intensity reached 5 × 1017 W/cm2 in a single mode propagating for more than 100 Rayleigh lengths.

The shape of ion tracks in natural apatite

NASA Astrophysics Data System (ADS)

Schauries, D.; Afra, B.; Bierschenk, T.; Lang, M.; Rodriguez, M. D.; Trautmann, C.; Li, W.; Ewing, R. C.; Kluth, P.

2014-05-01

Small angle X-ray scattering measurements were performed on natural apatite of different thickness irradiated with 2.2 GeV Au swift heavy ions. The evolution of the track radius along the full ion track length was estimated by considering the electronic energy loss and the velocity of the ions. The shape of the track is nearly cylindrical, slightly widening with a maximum diameter approximately 30 μm before the ions come to rest, followed by a rapid narrowing towards the end within a cigar-like contour. Measurements of average ion track radii in samples of different thicknesses, i.e. containing different sections of the tracks are in good agreement with the shape estimate.

Helical Turing patterns in the Lengyel-Epstein model in thin cylindrical layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bánsági, T.; Taylor, A. F., E-mail: A.F.Taylor@sheffield.ac.uk

2015-06-15

The formation of Turing patterns was investigated in thin cylindrical layers using the Lengyel-Epstein model of the chlorine dioxide-iodine-malonic acid reaction. The influence of the width of the layer W and the diameter D of the inner cylinder on the pattern with intrinsic wavelength l were determined in simulations with initial random noise perturbations to the uniform state for W < l/2 and D ∼ l or lower. We show that the geometric constraints of the reaction domain may result in the formation of helical Turing patterns with parameters that give stripes (b = 0.2) or spots (b = 0.37) in two dimensions. For b = 0.2, the helices weremore » composed of lamellae and defects were likely as the diameter of the cylinder increased. With b = 0.37, the helices consisted of semi-cylinders and the orientation of stripes on the outer surface (and hence winding number) increased with increasing diameter until a new stripe appeared.« less

Interaction of Highly Underexpanded Jets with Simulated Lunar Surfaces

NASA Technical Reports Server (NTRS)

Stitt, Leonard E.

1961-01-01

Pressure distributions and erosion patterns on simulated lunar surfaces (hard and soft) and interference effects between the surface and two representative lunar vehicles (cylindrical and spherical) were obtained with cold-air jets at various descent heights and nozzle total-pressure ratios up to 288,000. Surface pressure distributions were dependent on both nozzle area ratio and, nozzle contour. Peak pressures obtained with a sonic nozzle agreed closely with those predicted theoretically for a near-sonic jet expanding into a vacuum. Short bell-shaped nozzles gave annular pressure distributions; the low center pressure resulted from the coalescence of shocks that originated within the nozzle. The high surface pressures were contained within a circle whose diameter was about 16 throat diameters, regardless of nozzle area ratio or contour. The peak pressure increased rapidly as the vehicle approached the surface; for example, at a descent height of 40 throat diameters the peak pressure was 0.4 percent of the chamber pressure, but increased to 6 percent at 13 throat diameters. The exhaust jet eroded a circular concave hole in white sand at descent heights from about 200 to 600 throat diameters. The hole diameter was about 225 throat diameters, while the depth was approximately 60 throat diameters. The sand particles, which formed a conical sheet at a semivertex angle of 50 deg, appeared to follow a ballistic trajectory and at no time struck the vehicle. An increase in pressure was measured on the base of the cylindrical lunar vehicle when it approached to within 14 throat diameters of the hard, flat surface. No interference effects were noted between the spherical model and the surface to descent heights as low as 8 throat diameters.

Apparatus and method for plasma processing of SRF cavities

NASA Astrophysics Data System (ADS)

Upadhyay, J.; Im, Do; Peshl, J.; Bašović, M.; Popović, S.; Valente-Feliciano, A.-M.; Phillips, L.; Vušković, L.

2016-05-01

An apparatus and a method are described for plasma etching of the inner surface of superconducting radio frequency (SRF) cavities. Accelerator SRF cavities are formed into a variable-diameter cylindrical structure made of bulk niobium, for resonant generation of the particle accelerating field. The etch rate non-uniformity due to depletion of the radicals has been overcome by the simultaneous movement of the gas flow inlet and the inner electrode. An effective shape of the inner electrode to reduce the plasma asymmetry for the coaxial cylindrical rf plasma reactor is determined and implemented in the cavity processing method. The processing was accomplished by moving axially the inner electrode and the gas flow inlet in a step-wise way to establish segmented plasma columns. The test structure was a pillbox cavity made of steel of similar dimension to the standard SRF cavity. This was adopted to experimentally verify the plasma surface reaction on cylindrical structures with variable diameter using the segmented plasma generation approach. The pill box cavity is filled with niobium ring- and disk-type samples and the etch rate of these samples was measured.

Test and Analysis of a Buckling-Critical Large-Scale Sandwich Composite Cylinder

NASA Technical Reports Server (NTRS)

Schultz, Marc R.; Sleight, David W.; Gardner, Nathaniel W.; Rudd, Michelle T.; Hilburger, Mark W.; Palm, Tod E.; Oldfield, Nathan J.

2018-01-01

Structural stability is an important design consideration for launch-vehicle shell structures and it is well known that the buckling response of such shell structures can be very sensitive to small geometric imperfections. As part of an effort to develop new buckling design guidelines for sandwich composite cylindrical shells, an 8-ft-diameter honeycomb-core sandwich composite cylinder was tested under pure axial compression to failure. The results from this test are compared with finite-element-analysis predictions and overall agreement was very good. In particular, the predicted buckling load was within 1% of the test and the character of the response matched well. However, it was found that the agreement could be improved by including composite material nonlinearity in the analysis, and that the predicted buckling initiation site was sensitive to the addition of small bending loads to the primary axial load in analyses.

Mechanical properties of friction stir welded butt joint of steel/aluminium alloys: effect of tool geometry

NASA Astrophysics Data System (ADS)

Syafiq, W. M.; Afendi, M.; Daud, R.; Mazlee, M. N.; Majid, M. S. Abdul; Lee, Y. S.

2017-10-01

This paper described the mechanical properties from hardness testing and tensile testing of Friction Stir Welded (FSW) materials. In this project, two materials of aluminium and steel are welded using conventional milling machine and tool designed with different profile and shoulder size. During welding the temperature along the weld line is collected using thermocouples. Threaded pins was found to produce stronger joints than cylindrical pins. 20 mm diameter shoulder tool welded a slightly stronger joint than 18 mm diameter one, as well as softer nugget zone due to higher heat input. Threaded pins also contributed to higher weld temperature than cylindrical pins due to increase in pin contact surface. Generally, higher temperatures were recorded in aluminium side due to pin offset away from steel.

Thermal neutron flux mapping in a head phantom

NASA Astrophysics Data System (ADS)

Lee, C. L.; Zhou, X.-L.; Harmon, J. F.; Bartholomay, R. W.; Harker, Y. D.; Kudchadker, R. J.

1999-02-01

Boron neutron capture therapy (BNCT) is a binary cancer treatment modality in which a boron-containing compound is preferentially loaded into a tumor, followed by irradiation by thermal neutrons. In accelerator-based BNCT, neutrons are produced by charged particle-induced reactions such as 7Li(p, n) 7Be. For deeply seated brain tumors, epithermal (1 eV to 10 kev) neutrons are needed to penetrate the skull cap and subsequently thermalize at the tumor location. Cell damage in BNCT is caused by the high linear energy transfer (LET) products from the 10B(n, α) 7Li reaction. Because the cross section for this reaction is of 1/ v character, the dose due to 10B has essentially the same spatial distribution as the thermal neutron flux. A cylindrical acrylic head phantom (15.24 cm diameter by 21.59 cm length) has been constructed to simulate the patient's head and neck, and acrylic spacers of varying width allow placement of small (active sizes: 0.635 cm diameter by 1.27 cm length and 1.5875 cm diameter by 2.54 cm length) BF 3 proportional counters at nearly all radial and axial locations. Measurements of the thermal flux have also been benchmarked with gold and indium foils (bare and cadmium covered), as well as MCNP simulations. Measurement of the thermal neutron flux using these small BF 3 counters is shown to be adequate for experimentally determining the spatial variation of the 10B dose in head phantoms for accelerator-based BNCT.

Two-point method uncertainty during control and measurement of cylindrical element diameters

NASA Astrophysics Data System (ADS)

Glukhov, V. I.; Shalay, V. V.; Radev, H.

2018-04-01

The topic of the article is devoted to the urgent problem of the reliability of technical products geometric specifications measurements. The purpose of the article is to improve the quality of parts linear sizes control by the two-point measurement method. The article task is to investigate methodical extended uncertainties in measuring cylindrical element linear sizes. The investigation method is a geometric modeling of the element surfaces shape and location deviations in a rectangular coordinate system. The studies were carried out for elements of various service use, taking into account their informativeness, corresponding to the kinematic pairs classes in theoretical mechanics and the number of constrained degrees of freedom in the datum element function. Cylindrical elements with informativity of 4, 2, 1 and θ (zero) were investigated. The uncertainties estimation of in two-point measurements was made by comparing the results of of linear dimensions measurements with the functional diameters maximum and minimum of the element material. Methodical uncertainty is formed when cylindrical elements with maximum informativeness have shape deviations of the cut and the curvature types. Methodical uncertainty is formed by measuring the element average size for all types of shape deviations. The two-point measurement method cannot take into account the location deviations of a dimensional element, so its use for elements with informativeness less than the maximum creates unacceptable methodical uncertainties in measurements of the maximum, minimum and medium linear dimensions. Similar methodical uncertainties also exist in the arbitration control of the linear dimensions of the cylindrical elements by limiting two-point gauges.

Reaction of Titanium and Zirconium Particles in Cylindrical Explosive Charges

NASA Astrophysics Data System (ADS)

Frost, David; Cairns, Malcolm; Goroshin, Samuel; Zhang, Fan

2007-06-01

The critical conditions for the reaction of high melting-point metallic particles (Ti, Zr) dispersed during the detonation of long cylindrical explosive charges have been investigated experimentally. The charges consisted of packed beds of either spherical titanium particles (with diameters of 35, 90, or 215 μm; AP&C, Inc.) or nonspherical zirconium particles (250 -- 500 μm or 500 -- 600 μm, Atlantic Equipment Eng., NJ) saturated with sensitized liquid nitromethane. For the titanium particles, a threshold particle diameter exists, above which self-sustained particle reaction is not observed, although some particle reaction occurs immediately behind the detonation front then rapidly quenches. For the smallest particles, the proportion of the conical particle cloud that reacts increases with charge diameter, suggesting that the reaction initiation is a competition between particle heating and expansion cooling of the products. For zirconium particles, no critical conditions exist; particle ignition was observed for all particle and charge diameters tested. In this case, interaction of the high pressure detonation wave with the particles is sufficient to initiate reaction at the particle surface after a delay time (˜ 10's μs), which is much less than the time required for thermal equilibration of the particles.

Development of a small single-ring OpenPET prototype with a novel transformable architecture.

PubMed

Tashima, Hideaki; Yoshida, Eiji; Inadama, Naoko; Nishikido, Fumihiko; Nakajima, Yasunori; Wakizaka, Hidekatsu; Shinaji, Tetsuya; Nitta, Munetaka; Kinouchi, Shoko; Suga, Mikio; Haneishi, Hideaki; Inaniwa, Taku; Yamaya, Taiga

2016-02-21

The single-ring OpenPET (SROP), for which the detector arrangement has a cylinder shape cut by two parallel planes at a slant angle to form an open space, is our original proposal for in-beam PET. In this study, we developed a small prototype of an axial-shift type SROP (AS-SROP) with a novel transformable architecture for a proof-of-concept. In the AS-SROP, detectors originally forming a cylindrical PET are axially shifted little by little. We designed the small AS-SROP prototype for 4-layer depth-of-interaction detectors arranged in a ring diameter of 250 mm. The prototype had two modes: open and closed. The open mode formed the SROP with the open space of 139 mm and the closed mode formed a conventional cylindrical PET. The detectors were simultaneously moved by a rotation handle allowing them to be transformed between the two modes. We evaluated the basic performance of the developed prototype and carried out in-beam imaging tests in the HIMAC using (11)C radioactive beam irradiation. As a result, we found the open mode enabled in-beam PET imaging at a slight cost of imaging performance; the spatial resolution and sensitivity were 2.6 mm and 5.1% for the open mode and 2.1 mm and 7.3% for the closed mode. We concluded that the AS-SROP can minimize the decrease of resolution and sensitivity, for example, by transforming into the closed mode immediately after the irradiation while maintaining the open space only for the in-beam PET measurement.

Feasibility of Using Lateral Mode Coupling Method for a Large Scale Ultrasound Phased Array for Noninvasive Transcranial Therapy

PubMed Central

Song, Junho; Hynynen, Kullervo

2009-01-01

A hemispherical-focused, ultrasound phased array was designed and fabricated using 1372 cylindrical piezoelectric transducers that utilize lateral coupling for noninvasive transcranial therapy. The cylindrical transducers allowed the electrical impedance to be reduced by at least an order of magnitude, such that effective operation could be achieved without electronic matching circuits. In addition, the transducer elements generated the maximum acoustic average surface intensity of 27 W/cm2. The array, driven at the low (306 kHz) or high frequency (840 kHz), achieved excellent focusing through an ex vivo human skull and an adequate beam steering range for clinical brain treatments. It could electronically steer the ultrasound beam over cylindrical volumes of 100 mm in diameter and 60 mm in height at 306 kHz, and 30-mm in diameter and 30-mm in height at 840 kHz. A scanning laser vibrometer was used to investigate the radial and length mode vibrations of the element. The maximum pressure amplitudes through the skull at the geometric focus were predicted to be 5.5 MPa at 306 kHz and 3.7 MPa at 840 kHz for RF power of 1 W on each element. This is the first study demonstrating the feasibility of using cylindrical transducer elements and lateral coupling in construction of ultrasound phased arrays. PMID:19695987

Effect of tracheal tube cuff shape on fluid leakage across the cuff: an in vitro study.

PubMed

Dave, M H; Frotzler, A; Spielmann, N; Madjdpour, C; Weiss, M

2010-10-01

This study compared the fluid leakage in the new 'tapered' shaped against the classic 'cylindrical' shaped tracheal tube cuffs when placed in different sized tracheas. The 7.5 mm internal diameter (ID) tracheal tube cuffs-Tapered Seal Guard (TSG), Standard Seal Guard (SSG), Hi-Lo, Microcuff, Ruesch, and Portex Profile-were compared in an in vitro apparatus. Vertical artificial tracheas with 16, 20, and 22 mm ID were intubated, 5 ml clear water was applied above the unlubricated tube cuffs, and fluid leakage was measured up to 60 min. Data of tapered vs non-tapered tube cuffs (16 observations) were compared for each tracheal diameter using the Mann-Whitney test. Median (range) fluid leakage (ml) at 60 min was 2.14 (0.05-4.88), 1.14 (0.00-4.84), and 0.13 (0.00-1.32), respectively, for 16, 20, and 22 mm tracheas in the TSG tube studies when compared with 4.58 (0.44-4.88), 2.21 (0.00-4.81), and 0.00 (0.00-4.81) in the SSG tube and 4.54 (1.54-4.82), 0.90 (0.00-4.49), and 4.85 (4.40-4.99) in the Microcuff tube studies. Leakage in all polyvinylchloride (PVC) tube cuffs was almost complete (5 ml) within 5 min (P<0.001). The tapered PU tube cuff was as effective as the cylindrical PU cuffs in smaller tracheal diameters and was more efficient than the cylindrical Microcuff PU tube cuff in larger tracheal diameter in preventing subglottic fluid leakage across the tube cuff tested in this in vitro study. PVC tube cuffs leaked much more and faster than PU cuffs.

The effect of geometry and operation conditions on the performance of a gas-liquid cylindrical cyclone separator with new structure

NASA Astrophysics Data System (ADS)

Han, Qing; Zhang, Chi; Xu, Bo; Chen, Jiangping

2013-07-01

The hydrodynamic flow behavior, effects of geometry and working conditions of a gas-liquid cylindrical cyclone separator with a new structure are investigated by computational fluid dynamic and experiment. Gas liquid cylindrical cyclone separator is widely used in oil industry, refrigeration system because of its simple structure, high separating efficiency, little maintenance and no moving parts nor internal devices. In this work, a gas liquid cylindrical cyclone separator with new structure used before evaporator in refrigeration system can remove the vapor from the mixture and make evaporator compact by improving its heat exchange efficiency with the lower inlet quality. It also decreases evaporator pressure drop and reduces compressor work. The two pipes are placed symmetrically which makes each of them can be treated as inlet. It means when the fluids flow reverse, the separator performance will not be influence. Four samples with different geometry parameters are tested by experiment with different inlet quality (0.18-0.33), inlet mass flow rate (65-100kg/h). Compared with the experimental data, CFD simulation results show a good agreement. Eulerian multiphase model and Reynolds Stress Turbulence model are applied in the CFD simulation and obtained the inner flow field such as phase path lines, tangential velocity profiles and pressure and volume of fraction distribution contours. The separator body diameter (24, 36, 48mm) and inlet diameter (3.84, 4.8, 5.76mm) decide the maximum tangential velocity which results in the centrifugal force. The tangential velocity profiles are simulated and compared among different models. The higher tangential velocity makes higher quality of gas outlet but high pressure drop at the same time. Decreasing the inlet diameter increases quality of gas outlet pipe and pressure drop. High gas outlet quality is cost at high pressure drop. Increasing of separator diameter makes gas outlet quality increase first and then decrease but the pressure drop decreases all the way. The offset (0, 2.4, 3.6mm) of gas outlet is an insensitive factor which influences the quality and pressure drop little.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brualla, Lorenzo, E-mail: lorenzo.brualla@uni-due.de; Zaragoza, Francisco J.; Sempau, Josep

Purpose: External beam radiotherapy is the only conservative curative approach for Stage I non-Hodgkin lymphomas of the conjunctiva. The target volume is geometrically complex because it includes the eyeball and lid conjunctiva. Furthermore, the target volume is adjacent to radiosensitive structures, including the lens, lacrimal glands, cornea, retina, and papilla. The radiotherapy planning and optimization requires accurate calculation of the dose in these anatomical structures that are much smaller than the structures traditionally considered in radiotherapy. Neither conventional treatment planning systems nor dosimetric measurements can reliably determine the dose distribution in these small irradiated volumes. Methods and Materials: The Montemore » Carlo simulations of a Varian Clinac 2100 C/D and human eye were performed using the PENELOPE and PENEASYLINAC codes. Dose distributions and dose volume histograms were calculated for the bulbar conjunctiva, cornea, lens, retina, papilla, lacrimal gland, and anterior and posterior hemispheres. Results: The simulated results allow choosing the most adequate treatment setup configuration, which is an electron beam energy of 6 MeV with additional bolus and collimation by a cerrobend block with a central cylindrical hole of 3.0 cm diameter and central cylindrical rod of 1.0 cm diameter. Conclusions: Monte Carlo simulation is a useful method to calculate the minute dose distribution in ocular tissue and to optimize the electron irradiation technique in highly critical structures. Using a voxelized eye phantom based on patient computed tomography images, the dose distribution can be estimated with a standard statistical uncertainty of less than 2.4% in 3 min using a computing cluster with 30 cores, which makes this planning technique clinically relevant.« less

A 2D analytical cylindrical gate tunnel FET (CG-TFET) model: impact of shortest tunneling distance

NASA Astrophysics Data System (ADS)

Dash, S.; Mishra, G. P.

2015-09-01

A 2D analytical tunnel field-effect transistor (FET) potential model with cylindrical gate (CG-TFET) based on the solution of Laplace’s equation is proposed. The band-to-band tunneling (BTBT) current is derived by the help of lateral electric field and the shortest tunneling distance. However, the analysis is extended to obtain the subthreshold swing (SS) and transfer characteristics of the device. The dependency of drain current, SS and transconductance on gate voltage and shortest tunneling distance is discussed. Also, the effect of scaling the gate oxide thickness and the cylindrical body diameter on the electrical parameters of the device is analyzed.

Monolithic integration of fine cylindrical glass microcapillaries on silicon for electrophoretic separation of biomolecules

PubMed Central

Cao, Zhen; Ren, Kangning; Wu, Hongkai; Yobas, Levent

2012-01-01

We demonstrate monolithic integration of fine cylindrical glass microcapillaries (diameter ∼1 μm) on silicon and evaluate their performance for electrophoretic separation of biomolecules. Such microcapillaries are achieved through thermal reflow of a glass layer on microstructured silicon whereby slender voids are moulded into cylindrical tubes. The process allows self-enclosed microcapillaries with a uniform profile. A simplified method is also described to integrate the microcapillaries with a sample-injection cross without the requirement of glass etching. The 10-mm-long microcapillaries sustain field intensities up to 90 kV/m and limit the temperature excursions due to Joule heating to a few degrees Celsius only. PMID:23874369

Integrated heat exchanger design for a cryogenic storage tank

NASA Astrophysics Data System (ADS)

Fesmire, J. E.; Tomsik, T. M.; Bonner, T.; Oliveira, J. M.; Conyers, H. J.; Johnson, W. L.; Notardonato, W. U.

2014-01-01

Field demonstrations of liquid hydrogen technology will be undertaken for the proliferation of advanced methods and applications in the use of cryofuels. Advancements in the use of cryofuels for transportation on Earth, from Earth, or in space are envisioned for automobiles, aircraft, rockets, and spacecraft. These advancements rely on practical ways of storage, transfer, and handling of liquid hydrogen. Focusing on storage, an integrated heat exchanger system has been designed for incorporation with an existing storage tank and a reverse Brayton cycle helium refrigerator of capacity 850 watts at 20 K. The storage tank is a 125,000-liter capacity horizontal cylindrical tank, with vacuum jacket and multilayer insulation, and a small 0.6-meter diameter manway opening. Addressed are the specific design challenges associated with the small opening, complete modularity, pressure systems re-certification for lower temperature and pressure service associated with hydrogen densification, and a large 8:1 length-to-diameter ratio for distribution of the cryogenic refrigeration. The approach, problem solving, and system design and analysis for integrated heat exchanger are detailed and discussed. Implications for future space launch facilities are also identified. The objective of the field demonstration will be to test various zero-loss and densified cryofuel handling concepts for future transportation applications.

A simple on-line arterial time-activity curve detector for [O-15] water PET studies

NASA Astrophysics Data System (ADS)

Wollenweber, S. D.; Hichwa, R. D.; Ponto, L. L. B.

1997-08-01

A simple, automated on-line detector system has been fabricated and implemented to detect the arterial time-activity curve (TAG) for bolus-injection [O-15] water PET studies. This system offers two significant improvements over existing systems: a pump mechanism is not required to control arterial blood flow through the detector and dispersion correction of the time-activity curve for dispersion in external tubing is unnecessary. The [O-15] positrons emanating from blood within a thin-walled, 0.134 cm inner-diameter plastic tube are detected by a 0.5 cm wide by 1.0 cm long by 0.1 cm thick plastic scintillator mounted to a miniature PMT. Photon background is reduced to insignificant levels by a 2.0 cm thick cylindrical lead shield. Mean cerebral blood flow (mCBF) determined from an autoradiographic model and from the TAC measured by 1-second automated sampling was compared to that calculated from a TAC acquired using 5-second integrated manual samples. Improvements in timing resolution (1-sec vs. 5-sec) cause small but significant differences between the two sampling methods. Dispersion is minimized due to small tubing diameters, short lengths of tubing between the radial arterial sampling site and the detector and the presence of a 3-way valve 10 cm proximal to the detector.

Track membranes with open pores used as diffractive filters for space-based x-ray and EUV solar observations.

PubMed

Dominique, Marie; Mitrofanov, A V; Hochedez, J-F; Apel, P Yu; Schühle, U; Pudonin, F A; Orelovich, O L; Zuev, S Yu; Bolsée, D; Hermans, C; BenMoussa, A

2009-02-10

We describe the fabrication and performance of diffractive filters designed for space-based x-ray and EUV solar observations. Unlike traditional thin film filters, diffractive filters can be made to have a high resistance against the destructive mechanical and acoustic loads of a satellite launch. The filters studied are made of plastic track-etched membranes that are metal-coated on one side only. They have all-through open cylindrical pores with diameters as small as 500 nm, limiting their transmittance to very short wavelengths. The spectral transmittance of various diffractive filters with different pore parameters was measured from the soft x-ray to the near IR range (namely, from 1-1100 nm).

J-PET: A New Technology for the Whole-body PET Imaging

NASA Astrophysics Data System (ADS)

Niedźwiecki, S.; Białas, P.; Curceanu, C.; Czerwiński, E.; Dulski, K.; Gajos, A.; Głowacz, B.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Kapłon, Ł.; Kisielewska-Kamińska, D.; Korcyl, G.; Kowalski, P.; Kozik, T.; Krawczyk, N.; Krzemień, W.; Kubicz, E.; Mohammed, M.; Pawlik-Niedźwiecka, M.; Pałka, M.; Raczyński, L.; Rudy, Z.; Sharma, N. G.; Sharma, S.; Shopa, R. Y.; Silarski, M.; Skurzok, M.; Wieczorek, A.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

The Jagiellonian Positron Emission Tomograph (J-PET) is the first PET built from plastic scintillators. J-PET prototype consists of 192 detection modules arranged axially in three layers forming a cylindrical diagnostic chamber with the inner diameter of 85 cm and the axial field-of-view of 50 cm. An axial arrangement of long strips of plastic scintillators, their small light attenuation, superior timing properties, and relative ease of the increase of the axial field-of-view opens promising perspectives for the cost effective construction of the whole-body PET scanner, as well as construction of MR and CT compatible PET inserts. Present status of the development of the J-PET tomograph will be presented and discussed.

Effects of tool handle dimension and workpiece orientation and size on wrist ulnar/radial torque strength, usability and discomfort in a wrench task.

PubMed

Dianat, Iman; Rahimi, Soleyman; Nedaei, Moein; Asghari Jafarabadi, Mohammad; Oskouei, Ali E

2017-03-01

The effects of tool handle dimension (three modified designs of wrenches with 30-50 mm diameter cylindrical handles and traditional design with rectangular cross-sectional (5 mm × 25 mm) handle), workpiece orientation (vertical/horizontal) and workpiece size (small/large) as well as user's hand size on wrist ulnar/radial (U/R) torque strength, usability and discomfort, and also the relationship between these variables were evaluated in a maximum torque task using wrenches. The highest and lowest levels of maximal wrist U/R torque strength were recorded for the 30 mm diameter handle and traditional wrench design, respectively. The prototype handle with 30 mm diameter, together with 40 mm diameter handle, was also better than other designs as they received higher usability ratings and caused less discomfort. The mean wrist torque strength exerted on a vertically oriented workpiece (in the sagittal plane) was 23.8% higher than that exerted on a horizontally oriented one (in the transverse plane). The user's hand size had no effect on torque exertions. The wrist torque strength and usability were negatively correlated with hand and finger discomfort ratings. The results are also discussed in terms of their implications for hand tool and workstation configuration in torque tasks involving wrenches. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measurements of Surfactant Squeeze-out Using Magnetically-Levitated Liquid Bridges

NASA Technical Reports Server (NTRS)

Rosenblatt, Charles

2004-01-01

Liquid bridges: Columns of liquid supported by two solid surfaces. These are generally opposing right circular cylinders in 0g. For a cylindrical bridge of length L and diameter d, in zero g, the maximum slenderness ratio Lambda [L/d] = pi [Rayleigh]. In the presence of gravity the cylindrical shape of an axisymmetric bridge tends to deform. Fluid has a volumetric magnetic susceptibility X. Magnetic levitation has numerous applications in studies of fluids, "soft" and "hard" condensed matter physics, and biophysics

DIFFUSION PUMP

DOEpatents

Levenson, L.

1963-09-01

A high-vacuum diffusion pump is described, featuring a novel housing geometry for enhancing pumping speed. An upright, cylindrical lower housing portion is surmounted by a concentric, upright, cylindrical upper housing portion of substantially larger diameter; an uppermost nozzle, disposed concentrically within the upper portion, is adapted to eject downwardly a conical sheet of liquid outwardly to impinge upon the uppermost extremity of the interior wall of the lower portion. Preferably this nozzle is mounted upon a pedestal rising coaxially from within the lower portion and projecting up into said upper portion. (AEC)

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.

Leakage effect analysis on the performance of a cylindrical adjustable inertance tube

NASA Astrophysics Data System (ADS)

Zhou, Wenjie; Pfotenhauer, John M.; Zhi, Xiaoqin

2018-04-01

The inertance tube plays a significant role in improving the performance of the Stirling type pulse tube cryocooler by providing the desired phase angle between the mass flow and pressure wave. The phase angle is highly depended on the inertance tube geometry, such as diameter and length. A cylindrical threaded root device with variable thread depth on the outer screw and inner screw creates an adjustable inertance tube whose diameter and length can be adjusted in the real time. However, due to its geometry imperfectness, the performance of this threaded inertance tube is reduced by the leaks through the roots between the two screws. Its phase angle shift ability is decreased by 30% with the leakage clearance thickness of 15.5 μm according to both the theoretical prediction and the experimental verification.

Composite drill pipe and method for forming same

DOEpatents

Leslie, James C; Leslie, II, James C; Heard, James; Truong, Liem; Josephson, Marvin

2014-04-15

Metal inner and outer fittings configured, the inner fitting configured proximally with an external flange and projecting distally to form a cylindrical barrel and stepped down-in-diameter to form an abutment shoulder and then projecting further distally to form a radially inwardly angled and distally extending tapered inner sleeve. An outer sleeve defining a torque tube is configured with a cylindrical collar to fit over the barrel and is formed to be stepped up in diameter in alignment with the first abutment shoulder to then project distally forming a radially outwardly tapered and distally extending bonding surface to cooperate with the inner sleeve to cooperate with the inner sleeve in forming a annular diverging bonding cavity to receive the extremity of a composite pipe to abut against the abutment shoulders and to be bonded to the respective bonding surfaces by a bond.

Directed self-assembly of diblock copolymers in cylindrical confinement: effect of underfilling and air-polymer interactions on configurations

NASA Astrophysics Data System (ADS)

Carpenter, Corinne L.; Delaney, Kris T.; Laachi, Nabil; Fredrickson, Glenn H.

2015-03-01

Directed self-assembly (DSA) of block copolymers has attracted attention for its use as a simple, cost- effective patterning tool for creating vertical interconnect access (VIA) channels in nanoelectronic devices.1, 2 This technique supplements existing lithographic technologies to allow for the creation of high-resolution cylindrical holes whose diameter and placement can be precisely controlled. In this study, we use self-consistent field theory (SCFT) simulations to investigate the equilibrium configurations of under-filled DSA systems with air-polymer interactions. We report on a series of SCFT simulations of our three species (PMMA-b-PS diblock and air) model in cylindrical confinement to explore the role of template diameter, under-fill fraction (i.e. volume fraction of air), air-polymer surface interaction and polymer-side wall/substrate interactions on equilibrium morphologies in an under-filled template with a free top surface. We identify parameters and system configurations where a meniscus appears and explore cases with PMMA-attractive, PS-attractive, and all-neutral walls to understand the effects of wall properties on meniscus geometry and DSA morphology. An important outcome is an understanding of the parameters that control the contact angle of the meniscus with the wall, as it is one of the simplest quantitative measures of the meniscus shape. Ultimately, we seek to identify DSA formulations, templates, and surface treatments with predictable central cylinder diameter and a shallow contact angle, as these factors would facilitate broad process windows and ease of manufacturing.

Fast DNA sieving through submicrometer cylindrical glass capillary matrix.

PubMed

Cao, Zhen; Yobas, Levent

2014-01-07

Here, we report on DNA electrophoresis through a novel artificial sieving matrix based on the highly regular submicrometer cylindrical glass capillary segments alternatingly arranged with wells. Such round capillaries pose a higher-order confinement resulting in a lower partition coefficient and greater entropic energy barrier while limiting the driving field strength to a small fraction of the applied electric field. In return, the separation can be performed at high average field strengths (up to 1.6 kV/cm) without encountering the field-dependent loss of resolving power. This leads to fast DNA sieving as demonstrated here on the capillaries of 750 nm in diameter. The 600 bp to 21 kbp long chains are shown to resolve within 4 min after having undergone a fairly limited number of entropic barriers (128 in total). The capillary matrix also exhibits a critical field threshold below which DNA bands fail to launch, and this occurs at a considerably greater magnitude than in other matrixes. The submicrometer capillaries are batch-fabricated on silicon through a fabrication process that does not require high-resolution advanced lithography or well-controlled wafer bonding techniques to define their critical dimension.

The conical stent in coronary artery improves hemodynamics compared with the traditional cylindrical stent.

PubMed

Yu, Yi; Zhou, Yujie; Ma, Qian; Jia, Shuo; Wu, Sijing; Sun, Yan; Liu, Xiaoli; Zhao, Yingxin; Liu, Yuyang; Shi, Dongmei

2017-01-15

This study sought to explore the efficacy of the conical stent implantation in the coronary artery by comparing the effects of cylindrical and conical stents on wall shear stress (WSS) and velocity of flow and fractional flow reserve (FFR). The traditional cylindrical stent currently used in the percutaneous coronary intervention (PCI) has a consistent diameter, which does not match the physiological change of the coronary artery. On the contrary, as a new patent, the conical stent with tapering lumen is consistent with the physiological change of vascular diameter. However, the effect of the conical stent implantation on the coronary hemodynamics remains unclear. The coronary artery, artery stenosis and two stent models were established by Solidworks software. All models were imported into the computational fluid dynamics (CFD) software ANSYS ICEM-CFD to establish the fluid model. After the boundary conditions were set, CFD analysis was proceeded to compare the effects of two stent implantation on the change of WSS, velocity of flow and FFR. Hemodynamic indexes including FFR, blood flow velocity distribution (BVD) and WSS were improved by either the cylindrical or the conical stent implantation. However, after the conical stent implantation, the change of FFR seemed to be slower and more homogenous; the blood flow velocity was more appropriate without any obvious blood stagnation and direction changes; the WSS after the conical stent implantation was uniform from the proximal to distal side of the stent. Compared with the cylindrical stent, the conical stent implantation in the coronary artery can make the changes of vascular hemodynamic more closer to the physiological condition, which can reduce the incidence of intra-stent restenosis and thrombosis, thus making it more suitable for PCI therapy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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.

Microstructure and properties of aluminium-aluminium oxide graded composite materials

NASA Astrophysics Data System (ADS)

Kamaruzaman, F. F.; Nuruzzaman, D. M.; Ismail, N. M.; Hamedon, Z.; Iqbal, A. K. M. A.; Azhari, A.

2018-03-01

In this research works, four-layered aluminium-aluminium oxide (Al-Al2O3) graded composite materials were fabricated using powder metallurgy (PM) method. In processing, metal-ceramic graded composite materials of 0%, 10%, 20% and 30% weight percentage of ceramic concentration were prepared under 30 ton compaction load using a cylindrical die-punch set made of steel. After that, two-step pressureless sintering was carried out at sintering temperature and time 600°C and 3 hours respectively. It was observed that the sintered cylindrical specimens of 30 mm diameter were prepared successfully. The graded composite specimens were analysed and the properties such as density, microstructure and hardness were measured. It was found that after sintering process, the diameter of the graded cylindrical structure was decreased. Using both Archimedes method and rule of mixture (ROM), he density of structure was measured. The obtained results revealed that the microvickers hardness was increased as the ceramic component increases in the graded layer. Moreover, it was observed that the interface of the graded structure is clearly distinguished within the multilayer stack and the ceramic particles are almost uniformly distributed in the Al matrix.

Monolithic Cylindrical Fused Silica Resonators with High Q Factors

PubMed Central

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

Longitudinally Controlled Modification of Cylindrical and Conical Track-Etched Poly(ethylene terephthalate) Pores Using an Electrochemically Assisted Click Reaction

DOE PAGES

Coceancigh, Herman; Tran-Ba, Khanh-Hoa; Siepser, Natasha; ...

2017-09-27

Here in this study, the longitudinally controlled modification of the inner surfaces of poly(ethylene terephthalate) (PET) track-etched pores was explored using an electrochemically assisted Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) click reaction. Cylindrical or conical PET track-etched pores were first decorated with ethynyl groups via the amidation of surface -COOH groups, filled with a solution containing Cu(II) and azide-tagged fluorescent dye, and then sandwiched between comb-shaped and planar gold electrodes. Cu(I) was produced at the comb-shaped working electrode by the reduction of Cu(II); it diffused along the pores toward the other electrode and catalyzed CuAAC between an azide-tagged fluorescent dye and amore » pore-tethered ethynyl group. The modification efficiency of cylindrical pores (ca. 1 μm in diameter) was assessed from planar and cross-sectional fluorescence microscope images of modified membranes. Planar images showed that pore modification took place only above the teeth of the comb-shaped electrode with a higher reaction yield for longer Cu(II) reduction times. Cross-sectional images revealed micrometer-scale gradient modification along the pore axis, which reflected a Cu(I) concentration profile within the pores, as supported by finite-element computer simulations. The reported approach was applicable to the asymmetric modification of cylindrical pores with two different fluorescent dyes in the opposite directions and also for the selective visualization of the tip and base openings of conical pores (ca. 3.5 μm in base diameter and ca. 1 μm in tip diameter). Lastly, the method based on electrochemically assisted CuAAC provides a controlled means to fabricate asymmetrically modified nanoporous membranes and, in the future, will be applicable for chemical separations and the development of sequential catalytic reactors.« less

Longitudinally Controlled Modification of Cylindrical and Conical Track-Etched Poly(ethylene terephthalate) Pores Using an Electrochemically Assisted Click Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coceancigh, Herman; Tran-Ba, Khanh-Hoa; Siepser, Natasha

Here in this study, the longitudinally controlled modification of the inner surfaces of poly(ethylene terephthalate) (PET) track-etched pores was explored using an electrochemically assisted Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) click reaction. Cylindrical or conical PET track-etched pores were first decorated with ethynyl groups via the amidation of surface -COOH groups, filled with a solution containing Cu(II) and azide-tagged fluorescent dye, and then sandwiched between comb-shaped and planar gold electrodes. Cu(I) was produced at the comb-shaped working electrode by the reduction of Cu(II); it diffused along the pores toward the other electrode and catalyzed CuAAC between an azide-tagged fluorescent dye and amore » pore-tethered ethynyl group. The modification efficiency of cylindrical pores (ca. 1 μm in diameter) was assessed from planar and cross-sectional fluorescence microscope images of modified membranes. Planar images showed that pore modification took place only above the teeth of the comb-shaped electrode with a higher reaction yield for longer Cu(II) reduction times. Cross-sectional images revealed micrometer-scale gradient modification along the pore axis, which reflected a Cu(I) concentration profile within the pores, as supported by finite-element computer simulations. The reported approach was applicable to the asymmetric modification of cylindrical pores with two different fluorescent dyes in the opposite directions and also for the selective visualization of the tip and base openings of conical pores (ca. 3.5 μm in base diameter and ca. 1 μm in tip diameter). Lastly, the method based on electrochemically assisted CuAAC provides a controlled means to fabricate asymmetrically modified nanoporous membranes and, in the future, will be applicable for chemical separations and the development of sequential catalytic reactors.« less

Heat Transfer to 36.75 and 45 degree Swept Blunt Leading Edges in Free Flight at Mach Numbers from 1.70 to 2.99 and From 2.50 to 4.05

NASA Technical Reports Server (NTRS)

ONeal, Robert L.

1960-01-01

A flight investigation has been conducted to study the heat transfer to swept-wing leading edges. A rocket-powered model was used for the investigation and provided data for Mach number ranges of 1.78 to 2.99 and 2.50 to 4.05 with corresponding free-stream Reynolds number per foot ranges of 13.32 x 10(exp 6) to 19.90 x 10(exp 6) and 2.85 x 10(exp 6) to 4.55 x 10(exp 6). The leading edges employed were cylindrically blunted wedges ', three of which were swept 450 with leading-edge diameters of 1/4, 1/2, and 3/4 inch and one swept 36-750 with a leading-edge diameter of 1/2 inch. In the high Reynolds number range, measured values of heat transfer were found to be much higher than those predicted by laminar theory and at the larger values of leading-edge diameter were approaching the values predicted by turbulent theory. For the low Reynolds number range a comparison between measured and theoretical heat transfer showed that increasing the leading-edge diameter resulted in turbulent flow on the cylindrical portion of the leading edge.

Formation of hexagonal boron nitride nanoscrolls induced by inclusion and exclusion of self-assembling molecules in solution process

NASA Astrophysics Data System (ADS)

Hwang, Da Young; Suh, Dong Hack

2014-05-01

Unlike nanoscrolls of 2D graphene, those of 2D h-BN have not been demonstrated, except for only a few experimental reports. Nanoscrolls of h-BN with high yields and reproducibility are first synthesized by a simple solution process. Inner-tube diameters of BNSs including LCAs, N-(2-aminoethyl)-3α-hydroxy-5β-cholan-24-amide, a bile acid derivative and self-assembling material, can be controlled by adjusting the diameter of the LCA fiber which is grown by self-assembly. TEM and SEM images show that BNSs have a tube-like morphology and the inner-tube diameter of BNSs can be controlled in the range from 20 to 60 nm for a smaller diameter, up to 300 nm for a larger diameter by LCA fiber growth inside the BNSs. Finally, open cylindrical BNSs with hollow cores were obtained by dissolving LCAs inside BNSs.Unlike nanoscrolls of 2D graphene, those of 2D h-BN have not been demonstrated, except for only a few experimental reports. Nanoscrolls of h-BN with high yields and reproducibility are first synthesized by a simple solution process. Inner-tube diameters of BNSs including LCAs, N-(2-aminoethyl)-3α-hydroxy-5β-cholan-24-amide, a bile acid derivative and self-assembling material, can be controlled by adjusting the diameter of the LCA fiber which is grown by self-assembly. TEM and SEM images show that BNSs have a tube-like morphology and the inner-tube diameter of BNSs can be controlled in the range from 20 to 60 nm for a smaller diameter, up to 300 nm for a larger diameter by LCA fiber growth inside the BNSs. Finally, open cylindrical BNSs with hollow cores were obtained by dissolving LCAs inside BNSs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00897a

Experimental constraints on the outgassing dynamics of basaltic magmas

NASA Astrophysics Data System (ADS)

Pioli, L.; Bonadonna, C.; Azzopardi, B. J.; Phillips, J. C.; Ripepe, M.

2012-03-01

The dynamics of separated two-phase flow of basaltic magmas in cylindrical conduits has been explored combining large-scale experiments and theoretical studies. Experiments consisted of the continuous injection of air into water or glucose syrup in a 0.24 m diameter, 6.5 m long bubble column. The model calculates vesicularity and pressure gradient for a range of gas superficial velocities (volume flow rates/pipe area, 10-2-102 m/s), conduit diameters (100-2 m), and magma viscosities (3-300 Pa s). The model is calibrated with the experimental results to extrapolate key flow parameters such as Co (distribution parameter) and Froude number, which control the maximum vesicularity of the magma in the column, and the gas rise speed of gas slugs. It predicts that magma vesicularity increases with increasing gas volume flow rate and decreases with increasing conduit diameter, until a threshold value (45 vol.%), which characterizes churn and annular flow regimes. Transition to annular flow regimes is expected to occur at minimum gas volume flow rates of 103-104 m3/s. The vertical pressure gradient decreases with increasing gas flow rates and is controlled by magma vesicularity (in bubbly flows) or the length and spacing of gas slugs. This study also shows that until conditions for separated flow are met, increases in magma viscosity favor stability of slug flow over bubbly flow but suggests coexistence between gas slugs and small bubbles, which contribute to a small fraction of the total gas outflux. Gas flow promotes effective convection of the liquid, favoring magma homogeneity and stable conditions.

Evaluation of static resistance of deep foundation [project summary].

DOT National Transportation Integrated Search

2017-06-01

Various types of deep foundations were investigated including steel H-piles, pre-stressed concrete piles, open cylindrical steel and concrete piles with diameters greater than 36 inches, and drilled shafts with partial length permanent casing. : The ...

Development of a miniature double-pass cylindrical mirror electron energy analyzer (DPCMA), and its application to Auger photoelectron coincidence spectroscopy (APECS)

NASA Astrophysics Data System (ADS)

Kobayashi, Eiichi; Seo, Junya; Nambu, Akira; Mase, Kazuhiko

2007-09-01

We have developed a miniature double-pass cylindrical mirror electron energy analyzer (DPCMA) with an outer diameter of 26 mm. The DPCMA consists of a shield for the electric field, inner and outer cylinders, two pinholes with a diameter of 2.0 mm, and an electron multiplier. By assembling the DPCMA in a coaxially symmetric mirror electron energy analyzer (ASMA) coaxially and confocally we developed an analyzer for Auger photoelectron coincidence spectroscopy (APECS). The performance was estimated by measuring the Si-LVV-Auger Si-1s-photoelectron coincidence spectra of clean Si(1 1 1). The electron-energy resolution of the DPCMA was estimated to be E/Δ E = 20. This value is better than that of the miniature single-pass CMA ( E/Δ E = 12) that was used in the previous APECS analyzer.

Detonation corner turning in vapor-deposited explosives using the micromushroom test

NASA Astrophysics Data System (ADS)

Tappan, Alexander S.; Yarrington, Cole D.; Knepper, Robert

2017-06-01

Detonation corner turning describes the ability of a detonation wave to propagate into unreacted explosive that is not immediately in the path normal to the wave. The classic example of corner turning is cylindrical and involves a small diameter explosive propagating into a larger diameter explosive as described by Los Alamos' Mushroom test (e.g. (Hill, Seitz et al. 1998)), where corner turning is inferred from optical breakout of the detonation wave. We present a complimentary method to study corner turning in millimeter-scale explosives through the use of vapor deposition to prepare the slab (quasi-2D) analog of the axisymmetric mushroom test. Because the samples are in a slab configuration, optical access to the explosive is excellent and direct imaging of the detonation wave and ``dead zone'' that results during corner turning is possible. Results are compared for explosives that demonstrate a range of behaviors, from pentaerythritol tetranitrate (PETN), which has corner turning properties that are nearly ideal; to HNAB (hexanitroazobenzene), which has corner turning properties that reveal a substantial dead zone. Results are discussed in the context of microstructure and detonation failure thickness.

Size Effect and Cylinder test on Several Commercial Explosives

NASA Astrophysics Data System (ADS)

Lauderbach, Lisa; Moua, Kou; Garza, Raul; Souers, Clark

2011-06-01

The size (diameter) effect and the Cylinder test results for ammonium nitrate/nitromethane, some ammonium nitrate/fuel oil mixes, Red Dot shotgun powder, Semtex 1A and Semtex H will be presented. A generalized detonation velocity format, valid for all detonation rates, will be discussed. A shot in cylindrical symmetry will be compared with the 1-D cylindrical size effect data. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Water-mediated interactions between hydrophobic and ionic species in cylindrical nanopores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaitheeswaran, S.; Reddy, G.; Thirumalai, D.

2009-03-07

We use Metropolis Monte Carlo and umbrella sampling to calculate the free energies of interaction of two methane molecules and their charged derivatives in cylindrical water-filled pores. Confinement strongly alters the interactions between the nonpolar solutes and completely eliminates the solvent separated minimum (SSM) that is seen in bulk water. The free energy profiles show that the methane molecules are either in contact or at separations corresponding to the diameter and the length of the cylindrical pore. Analytic calculations that estimate the entropy of the solutes, which are solvated at the pore surface, qualitatively explain the shape of the freemore » energy profiles. Adding charges of opposite sign and magnitude 0.4e or e (where e is the electronic charge) to the methane molecules decreases their tendency for surface solvation and restores the SSM. We show that confinement induced ion-pair formation occurs whenever l{sub B}/D{approx}O(1), where l{sub B} is the Bjerrum length and D is the pore diameter. The extent of stabilization of the SSM increases with ion charge density as long as l{sub B}/D<1. In pores with D{<=}1.2 nm, in which the water is strongly layered, increasing the charge magnitude from 0.4e to e reduces the stability of the SSM. As a result, ion-pair formation that occurs with negligible probability in the bulk is promoted. In larger diameter pores that can accommodate a complete hydration layer around the solutes, the stability of the SSM is enhanced.« less

Effect of rotor configuration on guyed tower and foundation designs and estimated costs for intermediate site horizontal axis wind turbines

NASA Technical Reports Server (NTRS)

Frederick, G. R.; Winemiller, J. R.; Savino, J. M.

1982-01-01

Three designs of a guyed cylindrical tower and its foundation for an intermediate size horizontal axis wind turbine generator are discussed. The primary difference in the three designs is the configuration of the rotor. Two configurations are two-blade rotors with teetering hubs - one with full span pitchable blades, the other with fixed pitch blades. The third configuration is a three-bladed rotor with a rigid hub and fixed pitch blades. In all configurations the diameter of the rotor is 38 meters and the axis of rotation is 30.4 meters above grade, and the power output is 200 kW and 400 kW. For each configuration the design is based upon for the most severe loading condition either operating wind or hurricane conditions. The diameter of the tower is selected to be 1.5 meters (since it was determined that this would provide sufficient space for access ladders within the tower) with guy rods attached at 10.7 meters above grade. Completing a design requires selecting the required thicknesses of the various cylindrical segments, the number and diameter of the guy rods, the number and size of soil anchors, and the size of the central foundation. The lower natural frequencies of vibration are determined for each design to ensure that operation near resonance does not occur. Finally, a cost estimate is prepared for each design. A preliminary design and cost estimate of a cantilever tower (cylindrical and not guyed) and its foundation is also presented for each of the three configurations.

Focused beams of fast neutral atoms in glow discharge plasma

NASA Astrophysics Data System (ADS)

Grigoriev, S. N.; Melnik, Yu. A.; Metel, A. S.; Volosova, M. A.

2017-06-01

Glow discharge with electrostatic confinement of electrons in a vacuum chamber allows plasma processing of conductive products in a wide pressure range of p = 0.01 - 5 Pa. To assist processing of a small dielectric product with a concentrated on its surface beam of fast neutral atoms, which do not cause charge effects, ions from the discharge plasma are accelerated towards the product and transformed into fast atoms. The beam is produced using a negatively biased cylindrical or a spherical grid immersed in the plasma. Ions accelerated by the grid turn into fast neutral atoms at p > 0.1 Pa due to charge exchange collisions with gas atoms in the space charge sheaths adjoining the grid. The atoms form a diverging neutral beam and a converging beam propagating from the grid in opposite directions. The beam propagating from the concave surface of a 0.24-m-wide cylindrical grid is focused on a target within a 10-mm-wide stripe, and the beam from the 0.24-m-diameter spherical grid is focused within a 10-mm-diameter circle. At the bias voltage U = 5 kV and p ˜ 0.1 Pa, the energy of fast argon atoms is distributed continuously from zero to eU ˜ 5 keV. The pressure increase to 1 Pa results in the tenfold growth of their equivalent current and a decrease in the mean energy by an order of magnitude, which substantially raises the efficiency of material etching. Sharpening by the beam of ceramic knife-blades proved that the new method for the generation of concentrated fast atom beams can be effectively used for the processing of dielectric materials in vacuum.

Polyelectrolyte layer-by-layer deposition in cylindrical nanopores.

PubMed

Lazzara, Thomas D; Lau, K H Aaron; Abou-Kandil, Ahmed I; Caminade, Anne-Marie; Majoral, Jean-Pierre; Knoll, Wolfgang

2010-07-27

Layer-by-layer (LbL) deposition of polyelectrolytes within nanopores in terms of the pore size and the ionic strength was experimentally studied. Anodic aluminum oxide (AAO) membranes, which have aligned, cylindrical, nonintersecting pores, were used as a model nanoporous system. Furthermore, the AAO membranes were also employed as planar optical waveguides to enable in situ monitoring of the LbL process within the nanopores by optical waveguide spectroscopy (OWS). Structurally well-defined N,N-disubstituted hydrazine phosphorus-containing dendrimers of the fourth generation, with peripherally charged groups and diameters of approximately 7 nm, were used as the model polyelectrolytes. The pore diameter of the AAO was varied between 30-116 nm and the ionic strength was varied over 3 orders of magnitude. The dependence of the deposited layer thickness on ionic strength within the nanopores is found to be significantly stronger than LbL deposition on a planar surface. Furthermore, deposition within the nanopores can become inhibited even if the pore diameter is much larger than the diameter of the G4-polyelectrolyte, or if the screening length is insignificant relative to the dendrimer diameter at high ionic strengths. Our results will aid in the template preparation of polyelectrolyte multilayer nanotubes, and our experimental approach may be useful for investigating theories regarding the partitioning of nano-objects within nanopores where electrostatic interactions are dominant. Furthermore, we show that the enhanced ionic strength dependence of polyelectrolyte transport within the nanopores can be used to selectively deposit a LbL multilayer atop a nanoporous substrate.

Shockwave Interaction with a Cylindrical Structure

NASA Astrophysics Data System (ADS)

Mulligan, Phillip

2017-06-01

An increased understanding of the shockwave interaction with a cylindrical structure is the foundation for developing a method to explosively seal a pipe similar to the Deepwater Horizon accident in the Gulf of Mexico. Shockwave interactions with a cylindrical structure have been a reoccurring focus of energetics research. Some of the most notable contributions of non-destructive tests are described in ``The Effects of Nuclear Weapons'' (Glasstone, 1962). The work presented by Glasstone examines shockwave interaction from a 20-megaton bomb with a cylindrical structure. However, the data is limited to a peak overpressure of less than 25 psi, requiring several miles between the structure and the charge. The research presented in the following paper expands on the work Glasstone described by examining the shockwaves from 90, 180, and 270-gram C-4 charges interacting with a 6-inch diameter cylindrical structure positioned 52-inches from the center of the charge. The three charge weights that were tested in this research generated a peak overpressures of approximately 15, 25, and 40 psi, respectively. This research examines the peak pressure and total impulse from each charge acting on the cylindrical structure as well as the formation of vortices on the ``backside'' of the cylinder surface. This paper describes the methodology and findings of this study as well as examines the causality and implications of its results on our understanding of the shockwave interaction with a cylindrical structure.

Multi-MA reflex triode research.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swanekamp, Stephen Brian; Commisso, Robert J.; Weber, Bruce V.

The Reflex Triode can efficiently produce and transmit medium energy (10-100 keV) x-rays. Perfect reflexing through thin converter can increase transmission of 10-100 keV x-rays. Gamble II experiment at 1 MV, 1 MA, 60 ns - maximum dose with 25 micron tantalum. Electron orbits depend on the foil thickness. Electron orbits from LSP used to calculate path length inside tantalum. A simple formula predicts the optimum foil thickness for reflexing converters. The I(V) characteristics of the diode can be understood using simple models. Critical current dominates high voltage triodes, bipolar current is more important at low voltage. Higher current (2.5more » MA), lower voltage (250 kV) triodes are being tested on Saturn at Sandia. Small, precise, anode-cathode gaps enable low impedance operation. Sample Saturn results at 2.5 MA, 250 kV. Saturn dose rate could be about two times greater. Cylindrical triode may improve x-ray transmission. Cylindrical triode design will be tested at 1/2 scale on Gamble II. For higher current on Saturn, could use two cylindrical triodes in parallel. 3 triodes in parallel require positive polarity operation. 'Triodes in series' would improve matching low impedance triodes to generator. Conclusions of this presentation are: (1) Physics of reflex triodes from Gamble II experiments (1 MA, 1 MV) - (a) Converter thickness 1/20 of CSDA range optimizes x-ray dose; (b) Simple model based on electron orbits predicts optimum thickness from LSP/ITS calculations and experiment; (c) I(V) analysis: beam dynamics different between 1 MV and 250 kV; (2) Multi-MA triode experiments on Saturn (2.5 MA, 250 kV) - (a) Polarity inversion in vacuum, (b) No-convolute configuration, accurate gap settings, (c) About half of current produces useful x-rays, (d) Cylindrical triode one option to increase x-ray transmission; and (3) Potential to increase Saturn current toward 10 MA, maintaining voltage and outer diameter - (a) 2 (or 3) cylindrical triodes in parallel, (b) Triodes in series to improve matching, (c) These concepts will be tested first on Gamble II.« less

In vitro optical quality of monofocal aspheric toric intraocular lenses: effect of cylindrical power.

PubMed

Ferrer-Blasco, Teresa; Domínguez-Vicent, Alberto; García-Lázaro, Santiago; Diez, María Amparo; Alfonso, José F; Esteve-Taboada, José J

2018-06-01

To assess the in vitro optical quality of monofocal aspheric toric intraocular lenses (IOLs) as a function of the cylindrical power. The in vitro optical quality of the AcrySof IQ Toric IOLs SN6AT2, SN6AT3, SN6AT4, SN6AT5 and SN6AT6 (Alcon Laboratories Inc., Forth Worth, TX, USA) was assessed with an instrument conceived for measuring Zernike's coefficients at 3.0- and 5.0-mm apertures. As a reference, the aspheric monofocal lens AcrySof IQ Aspheric SN60WF (Alcon Laboratories Inc., Forth Worth, TX, USA) was also measured. The area of visibility and cut-off frequency were used to describe the modulation transfer function (MTF) of each lens; meanwhile, the light in the bucket and the diameter of a circular area centred on the point-spread function (PSF) peak that captures 50% of the light energy were used to describe the PSF of each lens. Finally, an image simulation was computed from the Zernike values with reference purposes. Small differences were found on the metrics used for describing the MTF and PSF of the lenses at both tested apertures, but these were not statistically significant (p > 0.05). Furthermore, the image simulation showed that these differences would not have clinical relevance at all. The optical performance of the AcrySof IQ toric IOLs in terms of MTF and PSF is good and seems to be independent of the cylindrical power and similar to a non-toric aspheric lens.

Fabrication of cylindrical micro-parts using synchronous rotary scan-projection lithography and chemical etching

NASA Astrophysics Data System (ADS)

Ito, Kaiki; Suzuki, Yuta; Horiuchi, Toshiyuki

2017-07-01

Lithographical patterning on the surface of a fine pipe with a thin wall is required for fabricating three-dimensional micro-parts. For this reason, a new exposure system for printing patterns on a cylindrical pipe by synchronous rotary scan-projection exposure was developed. Using the exposure system, stent-like resist patterns with a width of 251 μm were printed on a surface of stainless-steel pipe with an outer diameter of 2 mm. The exposure time was 30 s. Next, the patterned pipe was chemically etched. As a result, a stent-like mesh pipe with a line width of 230 μm was fabricated. It was demonstrated that the new method had a potential to be applied to fabrications of stent and other cylindrical micro-parts.

Plasma rotation in the Peking University Plasma Test device.

PubMed

Xiao, Chijie; Chen, Yihang; Yang, Xiaoyi; Xu, Tianchao; Wang, Long; Xu, Min; Guo, Dong; Yu, Yi; Lin, Chen

2016-11-01

Some preliminary results of plasma rotations in a linear plasma experiment device, Peking University Plasma Test (PPT) device, are reported in this paper. PPT has a cylindrical vacuum chamber with 500 mm diameter and 1000 mm length, and a pair of Helmholtz coils which can generate cylindrical or cusp magnetic geometry with magnitude from 0 to 2000 G. Plasma was generated by a helicon source and the typical density is about 10 13 cm -3 for the argon plasma. Some Langmuir probes, magnetic probes, and one high-speed camera are set up to diagnose the rotational plasmas. The preliminary results show that magnetic fluctuations exist during some plasma rotation processes with both cylindrical and cusp magnetic geometries, which might be related to some electromagnetic processes and need further studies.

The sagitta and lens thickness: the exact solution and a matrix approximation for lenses with toric, spherical, and cylindrical surfaces.

PubMed

Harris, W F

1989-03-01

The exact equation for sagitta of spherical surfaces is generalized to toric surfaces which include spherical and cylindrical surfaces as special cases. Lens thickness, therefore, can be calculated accurately anywhere on a lens even in cases of extreme spherical and cylindrical powers and large diameters. The sagittae of tire- and barrel-form toric surfaces differ off the principal meridians, as is shown by a numerical example. The same holds for pulley- and capstan-form toric surfaces. A general expression is given for thickness at an arbitrary point on a toric lens. Approximate expressions are derived and re-expressed in terms of matrices. The matrix provides an elegant means of generalizing equations for spherical surfaces and lenses to toric surfaces and lenses.

Nanoscale Capillary Flows in Alumina: Testing the Limits of Classical Theory.

PubMed

Lei, Wenwen; McKenzie, David R

2016-07-21

Anodic aluminum oxide (AAO) membranes have well-formed cylindrical channels, as small as 10 nm in diameter, in a close packed hexagonal array. The channels in AAO membranes simulate very small leaks that may be present for example in an aluminum oxide device encapsulation. The 10 nm alumina channel is the smallest that has been studied to date for its moisture flow properties and provides a stringent test of classical capillary theory. We measure the rate at which moisture penetrates channels with diameters in the range of 10 to 120 nm with moist air present at 1 atm on one side and dry air at the same total pressure on the other. We extend classical theory for water leak rates at high humidities by allowing for variable meniscus curvature at the entrance and show that the extended theory explains why the flow increases greatly when capillary filling occurs and enables the contact angle to be determined. At low humidities our measurements for air-filled channels agree well with theory for the interdiffusive flow of water vapor in air. The flow rate of water-filled channels is one order of magnitude less than expected from classical capillary filling theory and is coincidentally equal to the helium flow rate, validating the use of helium leak testing for evaluating moisture flows in aluminum oxide leaks.

Compensating for Attenuation Differences in Ultrasonic Inspections of Titanium-Alloy Billets

NASA Astrophysics Data System (ADS)

Margetan, F. J.; Thompson, R. B.; Keller, Michael; Hassan, Waled

2004-02-01

Cylindrical billets of Titanium alloy are ultrasonically inspected prior to use in fabricating rotating jet-engine components. Although each billet has a cylindrical geometry, its ultrasonic properties are not cylindrically symmetric due to asymmetries in the process used to produce the billet from the original cast ingot. In the inspection process, a calibration standard of the same diameter containing flat-bottomed hole (FBH) reflectors is used to set the initial inspection gain (i.e., the signal amplification level). If the ultrasonic attenuation of the billet to be inspected differs significantly from that of the calibration standard, the inspection gain must be adjusted to maintain the desired defect detection sensitivity. In this paper we investigate several schemes for attenuation compensation. The gain adjustments fall into two broad categories: "global" adjustments (in dB/inch units), which are applied uniformly throughout the billet under inspection; and "local adjustments", which vary with axial and circumferential position. The schemes make use of the patterns of reflected back-wall amplitude and backscattered grain noise seen in the calibration standard and test billet. The various compensation schemes are tested using specimens of 6″-diameter Ti-6A1-4V billet into which many FBH targets were drilled. Results are summarized and tentative recommendations for improving billet inspection practices are offered.

Analysis of dry friction damping characteristics for short cylindrical shell structures

NASA Astrophysics Data System (ADS)

Wang, Nengmao; Wang, Yanrong

2018-05-01

An efficient mathematical model to describe the friction of short cylindrical shell structures with a dry friction damping sleeve is proposed. The frictional force in the circumference and axial direction is caused by the opposing bending strains at the interface. Slipping will occur at part region of the interface and the mathematic model of the slipping region is established. Ignoring the effect of contact stiffness on the vibration analysis, the friction energy dissipation capability of damping sleeve would be calculated. Structural vibration mode, positive pressure at the interface and vibration stress of the short cylindrical shell structures is analyzed as influence factors to the critical damping ratio. The results show that the circumferential friction energy dissipation is more sensitive to the number of nodal diameter, and the circumferential friction damping ratio increases rapidly with the number of nodal diameter. The slipping frictional force would increase along with the positive pressure, but the slipping region would decrease with it. The peak damping ratio keeps nearly constant. But the vibration stress corresponding to peak damping ratio would increases with the positive pressure. The dry friction damping ratio of damping sleeve contains the effect of frictional force in the circumference and axial direction, and the axial friction plays a major role.

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.

Development of a superconducting bulk magnet for NMR and MRI.

PubMed

Nakamura, Takashi; Tamada, Daiki; Yanagi, Yousuke; Itoh, Yoshitaka; Nemoto, Takahiro; Utumi, Hiroaki; Kose, Katsumi

2015-10-01

A superconducting bulk magnet composed of six vertically stacked annular single-domain c-axis-oriented Eu-Ba-Cu-O crystals was energized to 4.74 T using a conventional superconducting magnet for high-resolution NMR spectroscopy. Shim coils, gradient coils, and radio frequency coils for high resolution NMR and MRI were installed in the 23 mm-diameter room-temperature bore of the bulk magnet. A 6.9 ppm peak-to-peak homogeneous region suitable for MRI was achieved in the central cylindrical region (6.2 mm diameter, 9.1 mm length) of the bulk magnet by using a single layer shim coil. A 21 Hz spectral resolution that can be used for high resolution NMR spectroscopy was obtained in the central cylindrical region (1.3 mm diameter, 4 mm length) of the bulk magnet by using a multichannel shim coil. A clear 3D MR image dataset of a chemically fixed mouse fetus with (50 μm)(3) voxel resolution was obtained in 5.5 h. We therefore concluded that the cryogen-free superconducting bulk magnet developed in this study is useful for high-resolution desktop NMR, MRI and mobile NMR device. Copyright © 2015 Elsevier Inc. All rights reserved.

Development of Ordered, Porous (Sub-25 nm Dimensions) Surface Membrane Structures Using a Block Copolymer Approach.

PubMed

Ghoshal, Tandra; Holmes, Justin D; Morris, Michael A

2018-05-08

In an effort to develop block copolymer lithography to create high aspect vertical pore arrangements in a substrate surface we have used a microphase separated poly(ethylene oxide) -b- polystyrene (PEO-b-PS) block copolymer (BCP) thin film where (and most unusually) PS not PEO is the cylinder forming phase and PEO is the majority block. Compared to previous work, we can amplify etch contrast by inclusion of hard mask material into the matrix block allowing the cylinder polymer to be removed and the exposed substrate subject to deep etching thereby generating uniform, arranged, sub-25 nm cylindrical nanopore arrays. Briefly, selective metal ion inclusion into the PEO matrix and subsequent processing (etch/modification) was applied for creating iron oxide nanohole arrays. The oxide nanoholes (22 nm diameter) were cylindrical, uniform diameter and mimics the original BCP nanopatterns. The oxide nanohole network is demonstrated as a resistant mask to fabricate ultra dense, well ordered, good sidewall profile silicon nanopore arrays on substrate surface through the pattern transfer approach. The Si nanopores have uniform diameter and smooth sidewalls throughout their depth. The depth of the porous structure can be controlled via the etch process.

Reaction of Titanium and Zirconium Particles in Cylindrical Explosive Charges

NASA Astrophysics Data System (ADS)

Frost, David L.; Cairns, Malcolm; Goroshin, Samuel; Zhang, Fan

2007-12-01

The critical conditions for the reaction of particles of the transition metals titanium (Ti) and zirconium (Zr) dispersed during the detonation of long cylindrical explosive charges have been investigated experimentally. The charges consisted of packed beds of either spherical Ti particles or irregularly shaped Zr particles saturated with sensitized liquid nitromethane. For the Ti particles, a threshold particle diameter exists of 65±25 μm, above which self-sustained particle reaction is not observed for charge diameters up to 49 mm, although some particle reaction occurs immediately behind the detonation front then rapidly quenches. For the smallest particles (40 μm), the proportion of the conical particle cloud that reacts increases with charge diameter, suggesting that the reaction is a competition between particle heating and expansion cooling of the products. For 375 and 550 μm Zr particles, particle ignition was observed for 19 and 41 mm dia charges. In this case, interaction of the detonation wave with the particles is sufficient to initiate reaction at the particle surface after a delay time (˜5 μs), which is much less than the time required for thermal equilibration of the particles.

Liquid oxygen dicting cleaned by falling film method

NASA Technical Reports Server (NTRS)

Paul, H. I.

1967-01-01

Principle of a vertical falling film is used to clean contaminated large diameter and length liquid oxygen /LOX/ cylindrical ducting. The cleaning cycle is performed by flowing trichloroethylene in a falling film down a vertically mounted duct for approximately one hour.

Overview of demonstrator program of Japanese Smart Materials and Structure System project

NASA Astrophysics Data System (ADS)

Tajima, Naoyuki; Sakurai, Tateo; Sasajima, Mikio; Takeda, Nobuo; Kishi, Teruo

2003-08-01

The Japanese Smart Material and Structure System Project started in 1998 as five years' program that funded by METI (Ministry of Economy, Trade and Industry) and supported by NEDO (New Energy and Industrial Technology Development Organization). Total budget of five years was finally about 3.8 billion Japanese yen. This project has been conducted as the Academic Institutions Centered Program, namely, one of collaborated research and development among seven universities (include one foreign university), seventeen Industries (include two foreign companies), and three national laboratories. At first, this project consisted of four research groups that were structural health monitoring, smart manufacturing, active/adaptive structures, and actuator material/devices. Two years later, we decided that two demonstrator programs should be added in order to integrate the developed sensor and actuator element into the smart structure system and verify the research and development results of above four research groups. The application target of these demonstrators was focused to the airplane, and two demonstrators that these shapes simulate to the fuselage of small commercial airplane (for example, Boeing B737) had been established. Both demonstrators are cylindrical structures with 1.5 m in diameter and 3 m in length that the first demonstrator has CFRP skin-stringer and the second one has CFRP skin. The first demonstrator integrates the following six innovative techniques: (1) impact monitoring using embedded small diameter optical fiber sensors newly developed in this program, (2) impact monitoring using the integrated acoustic emission (AE) systems, (3) whole-field strain mapping using the BOTDR/FBG integrated system, (4) damage suppression using embedded shape memory alloy (SMA) films, (5) maximum and cyclic strain sensing using smart composite patches, and (6) smart manufacturing using the integrated sensing system. The second one is for demonstrating the suppression of vibration and acoustic noise generated in the composite cylindrical structure. In this program, High-performance PZT actuators/sensors developed in this program are also installed. The whole tests and evaluations have now been finished. This paper presents the outline of demonstrator programs, followed by six presentations that show the detail verification results of industrial demonstration themes.

Validation of a Hartmann-Moiré wavefront sensor with large dynamic range.

PubMed

Wei, Xin; Van Heugten, Tony; Thibos, Larry

2009-08-03

Our goal was to validate the accuracy, repeatability, sensitivity, and dynamic range of a Hartmann-Moiré (HM) wavefront sensor (PixelOptics, Inc.) designed for ophthalmic applications. Testing apparatus injected a 4 mm diameter monochromatic (532 nm) beam of light into the wavefront sensor for measurement. Controlled amounts of defocus and astigmatism were introduced into the beam with calibrated spherical (-20D to + 18D) and cylindrical (-8D to + 8D) lenses. Repeatability was assessed with three repeated measurements within a 2-minute period. Correlation coefficients between mean wavefront measurements (n = 3) and expected wavefront vergence for both sphere and cylinder lenses were >0.999. For spherical lenses, the sensor was accurate to within 0.1D over the range from -20D to + 18D. For cylindrical lenses, the sensor was accurate to within 0.1D over the range from -8D to + 8D. The primary limitation to demonstrating an even larger dynamic range was the increasingly critical requirements for optical alignment. Sensitivity to small changes of vergence was constant over the instrument's full dynamic range. Repeatability of measurements for fixed condition was within 0.01D. The Hartmann-Moiré wavefront sensor measures defocus and astigmatism accurately and repeatedly with good sensitivity over a large dynamic range required for ophthalmic applications.

Real-time direct measurement of liquid (water) evaporation by simple disturbance inhibited interfometry technique

NASA Astrophysics Data System (ADS)

Kim, Yong Gi

2017-11-01

A real-time in-situ interferometry method was proposed to measure water (liquid) evaporation directly over the liquid surface inside the reservoir. The direct evaporation measurement relied on the counting the number of sinusoidal fringes. As the water inside reservoir evaporated, the depth of the water decreases a little thus the optical path length changes. Evaporation signals have been determined as a function of the focusing beam position of the signal beam over the liquid surface. In interferometry technique, the most limiting factors are surface disturbances and vibrations over the liquid surface. This limiting factor was simply inhibited by placing a long cylindrical aluminum tube around the signal beam of the interferometer over the liquid surface. A small diameter cylindrical Al tube diminished vibrations and wind induced surface ripples more effectively than that of the larger one. Water evaporation was successfully measured in real-time with a warm water and cold water even under windy condition with an electric fan. The experimental results demonstrated that the interferometry technique allows determining of liquid evaporation in real-time. Interferometric technique opens up a new possibility of methodology for liquid evaporation measurement even in several environmental disturbances, such as, vibration, surface disturbance, temperature change and windy environments.

Compressible sleeve provides automatic centering for grinding or turning of cylinders

NASA Technical Reports Server (NTRS)

Rohrer, J. A.

1968-01-01

Elastomeric sleeve supported on a threaded mandrel automatically centers cylindrical castings for grinding or turning. By expanding the diameter of the sleeve with pressure against the ends, the casting becomes rigidly supported and the surfacing operation can be completed.

Phospholipid Nonwoven Electrospun Membranes

NASA Astrophysics Data System (ADS)

McKee, Matthew G.; Layman, John M.; Cashion, Matthew P.; Long, Timothy E.

2006-01-01

Nonwoven fibrous membranes were formed from electrospinning lecithin solutions in a single processing step. As the concentration of lecithin increased, the micellar morphology evolved from spherical to cylindrical, and at higher concentrations the cylindrical micelles overlapped and entangled in a fashion similar to polymers in semi-dilute or concentrated solutions. At concentrations above the onset of entanglements of the wormlike micelles, electrospun fibers were fabricated with diameters on the order of 1 to 5 micrometers. The electrospun phospholipid fibers offer the potential for direct fabrication of biologically based, high-surface-area membranes without the use of multiple synthetic steps, complicated electrospinning designs, or postprocessing surface treatments.

Supercooling Water in Cylindrical Capsules

NASA Astrophysics Data System (ADS)

Guzman, J. J. Milón; Braga, S. L.

2005-11-01

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

Investigation of Perforated Convergent-divergent Diffusers with Initial Boundary Layer

NASA Technical Reports Server (NTRS)

Weinstein, Maynard I

1950-01-01

An experimental investigation was made at Mach number 1.90 of the performance of a series of perforated convergent-divergent supersonic diffusers operating with initial boundary layer, which was induced and controlled by lengths of cylindrical inlets affixed to the diffusers. Supercritical mass-flow and peak total-pressure recoveries were decreased slightly by use of the longest inlets (4 inlet diameters in length). Combinations of cylindrical inlets, perforated diffusers, and subsonic diffuser were evaluated as simulated wind tunnels having second throats. Comparisons with noncontracted configurations of similar scale indicated conservatively computed power reductions of 25 percent.

A Study of the Electrostatic Interaction Between Insulators and Martian/Lunar Soil Simulants

NASA Technical Reports Server (NTRS)

Mantovani, James G.

2001-01-01

Using our previous experience with the Mars Environmental Compatibility Assessment (MECA) electrometer, we have designed a new type of aerodynamic electrometer. The goal of the research was to measure the buildup of electrostatic surface charge on a stationary cylindrical insulator after windborne granular particles have collided with the insulator surface in a simulated dust storm. The experiments are performed inside a vacuum chamber. This allows the atmospheric composition and pressure to be controlled in order to simulate the atmospheric conditions near the equator on the Martian surface. An impeller fan was used to propel the dust particles at a cylindrically shaped insulator under low vacuum conditions. We tested the new electrometer in a 10 mbar CO2 atmosphere by exposing two types of cylindrical insulators, Teflon (1.9 cm diameter) and Fiberglass (2.5 cm diameter), to a variety of windborne granular particulate materials. The granular materials tested were JSC Mars-1 simulant, which is a mixture of coarse and fine (<5microns diameter) particle sizes, and some of the major mineral constituents of the Martian soil. The minerals included Ottawa sand (SiO2), iron oxide (Fe2O3), aluminum oxide (Al2O3) and magnesium oxide (MgO). We also constructed a MECA-like electrometer that contained an insulator capped planar electrode for measuring the amount of electrostatic charge produced by rubbing an insulator surface over Martian and lunar soil simulants. The results of this study indicate that it is possible to detect triboelectric charging of insulator surfaces by windborne Martian soil simulant, and by individual mineral constituents of the soil simulant. We have also found that Teflon and Fiberglass insulator surfaces respond in different ways by developing opposite polarity surface charge, which decays at different rates after the particle impacts cease.

Optical distortion correction of a liquid-gas interface and contact angle in cylindrical tubes

NASA Astrophysics Data System (ADS)

Darzi, Milad; Park, Chanwoo

2017-05-01

Objects inside cylindrical tubes appear distorted as seen outside the tube due to the refraction of the light passing through different media. Such an optical distortion may cause significant errors in geometrical measurements using optical observations of objects (e.g., liquid-gas interfaces, solid particles, gas bubbles) inside the tubes. In this study, an analytical method using a point-by-point correction of the optical distortion was developed. For an experimental validation, the method was used to correct the apparent profiles of the water-air interfaces (menisci) in cylindrical glass tubes with different tube diameters and wall thicknesses. Then, the corrected meniscus profiles were used to calculate the corrected static contact angles. The corrected contact angle shows an excellent agreement with the reference contact angles as compared to the conventional contact angle measurement using apparent meniscus profiles.

Influence of detector pixel size, TOF resolution and DOI on image quality in MR-compatible whole-body PET.

PubMed

Thoen, Hendrik; Keereman, Vincent; Mollet, Pieter; Van Holen, Roel; Vandenberghe, Stefaan

2013-09-21

The optimization of a whole-body PET system remains a challenging task, as the imaging performance is influenced by a complex interaction of different design parameters. However, it is not always clear which parameters have the largest impact on image quality and are most eligible for optimization. To determine this, we need to be able to assess their influence on image quality. We performed Monte-Carlo simulations of a whole-body PET scanner to predict the influence on image quality of three detector parameters: the TOF resolution, the transverse pixel size and depth-of-interaction (DOI)-correction. The inner diameter of the PET scanner was 65 cm, small enough to allow physical integration into a simultaneous PET-MR system. Point sources were used to evaluate the influence of transverse pixel size and DOI-correction on spatial resolution as function of radial distance. To evaluate the influence on contrast recovery and pixel noise a cylindrical phantom of 35 cm diameter was used, representing a large patient. The phantom contained multiple hot lesions with 5 mm diameter. These lesions were placed at radial distances of 50, 100 and 150 mm from the center of the field-of-view, to be able to study the effects at different radial positions. The non-prewhitening (NPW) observer was used for objective analysis of the detectability of the hot lesions in the cylindrical phantom. Based on this analysis the NPW-SNR was used to quantify the relative improvements in image quality due to changes of the variable detector parameters. The image quality of a whole-body PET scanner can be improved significantly by reducing the transverse pixel size from 4 to 2.6 mm and improving the TOF resolution from 600 to 400 ps and further from 400 to 200 ps. Compared to pixel size, the TOF resolution has the larger potential to increase image quality for the simulated phantom. The introduction of two layer DOI-correction only leads to a modest improvement for the spheres at radial distance of 150 mm from the center of the transaxial FOV.

Reaction Rate of Small Diffusing Molecules on a Cylindrical Membrane

NASA Astrophysics Data System (ADS)

Straube, Ronny; Ward, Michael J.; Falcke, Martin

2007-10-01

Biomembranes consist of a lipid bi-layer into which proteins are embedded to fulfill numerous tasks in localized regions of the membrane. Often, the proteins have to reach these regions by simple diffusion. Motivated by the observation that IP3 receptor channels (IP3R) form clusters on the surface of the endoplasmic reticulum (ER) during ATP-induced calcium release, the reaction rate of small diffusing molecules on a cylindrical membrane is calculated based on the Smoluchowski approach. In this way, the cylindrical topology of the tubular ER is explicitly taken into account. The problem can be reduced to the solution of the diffusion equation on a finite cylindrical surface containing a small absorbing hole. The solution is constructed by matching appropriate `inner' and `outer' asymptotic expansions. The asymptotic results are compared with those from numerical simulations and excellent agreement is obtained. For realistic parameter sets, we find reaction rates in the range of experimentally measured clustering rates of IP3R. This supports the idea that clusters are formed by a purely diffusion limited process.

Connector tube for a turbine rotor cooling circuit

DOEpatents

Li, Ming Cheng

2003-06-24

A tubular connector adapted to extend between two tubular components comprising a tubular body having an internal diameter, a first free end including an annular radial flange having a tapered surface adapted to engage a complementary seating surface on a first of the two tubular components, the internal diameter remaining constant through the first free end; and a second free end having an annular bulbous shape adapted to seat within a cylindrical end of a second of the two tubular components.

Connector tube for a turbine rotor cooling circuit

DOEpatents

Li, Ming Cheng

2002-01-01

A tubular connector adapted to extend between two tubular components comprising a tubular body having an internal diameter, a first free end including an annular radial flange having a tapered surface adapted to engage a complementary seating surface on a first of the two tubular components, the internal diameter remaining constant through the first free end; and a second free end having an annular bulbous shape adapted to seat within a cylindrical end of a second of the two tubular components.

23RD International Conference on Phenomena in Ionized Gases, Volume 5

DTIC Science & Technology

1998-12-01

eNm.f, generated within the plasma is given by section with a 5-cm diameter. The magnetic field was Vof = wh Bt p i vn provided by an iron- core ...cylindrical tungsten probes, of 0.038cm. as impurities can be centrifuged as reported by diameter, insulated by thin glass tube except their tips Bonnevier...Norfolk, VA 213529 1. Discharge modes discharge begins, at several hundred Torr, to change from a hollow cathode discharge into what we Experimental

Geometry effects on cooling in a standing wave cylindrical thermoacousic resonator

NASA Astrophysics Data System (ADS)

Mohd-Ghazali, Normah; Ghazali, Ahmad Dairobi; Ali, Irwan Shah; Rahman, Muhammad Aminullah A.

2012-06-01

Numerous reports have established the refrigeration applications of thermoacoustic cooling without compressors and refrigerants. Significant cooling effects can be obtained in a thermoacoustic resonator fitted with a heat exchanging stack and operated at resonance frequency. Past studies, however, have hardly referred to the fundamental relationship between resonant frequency and the resonator geometry. This paper reports the thermoacoustic cooling effects at resonance obtained by changing the diameter of the resonator while holding the length constant and vice versa. Experiments were completed at atmospheric pressure with air as the working fluid using a number of pvc tubes having parallel plate stack from Mylar. The temperature difference measured across the stack showed that a volume increase in the working fluid in general increases the temperature gradient for the quarter-and half-wavelength resonators. Doubling the diameter from 30 mm to 60 mm produced the highest temperature difference due to the greater number of stack plates resulting in a higher overall thermoacaoustic cooling. Increasing the resonator length only produced a small increase in temperature gradient since the resonant frequency at operation is only slightly changed. Investigation on the aspect ratio exhibits no influence on the temperature difference across the stack. This study have shown that the resonator length and diameter do affect the temperature difference across the thermoacoustic stack, and further research should be done to consider the contribution of the stack mass on the overall desired thermoacoustic cooling.

Micro pulling down growth of very thin shape memory alloys single crystals

NASA Astrophysics Data System (ADS)

López-Ferreño, I.; Juan, J. San; Breczewski, T.; López, G. A.; Nó, M. L.

Shape memory alloys (SMAs) have attracted much attention in the last decades due to their thermo-mechanical properties such as superelasticity and shape memory effect. Among the different families of SMAs, Cu-Al-Ni alloys exhibit these properties in a wide range of temperatures including the temperature range of 100-200∘C, where there is a technological demand of these functional materials, and exhibit excellent behavior at small scale making them more competitive for applications in Micro Electro-Mechanical Systems (MEMS). However, polycrystalline alloys of Cu-based SMAs are very brittle so that they show their best thermo-mechanical properties in single-crystal state. Nowadays, conventional Bridgman and Czochralski methods are being applied to elaborate single-crystal rods up to a minimum diameter of 1mm, but no works have been reported for smaller diameters. With the aim of synthesizing very thin single-crystals, the Micro-Pulling Down (μ-PD) technique has been applied, for which the capillarity and surface tension between crucible and the melt play a critical role. The μ-PD method has been successfully applied to elaborate several cylindrical shape thin single-crystals down to 200μm in diameter. Finally, the martensitic transformation, which is responsible for the shape memory properties of these alloys, has been characterized for different single-crystals. The experimental results evidence the good quality of the grown single-crystals.

Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller Bearings

NASA Technical Reports Server (NTRS)

Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

2012-01-01

The effect of internal clearance on radially loaded deepgroove ball and cylindrical roller bearing load distribution and fatigue life was determined for four clearance groups defined in the bearing standards. The analysis was extended to negative clearance (interference) conditions to produce a curve of life factor versus internal clearance. Rolling-element loads can be optimized and bearing life maximized for a small negative operating clearance. Life declines gradually with positive clearance and rapidly with increasing negative clearance. Relationships were found between bearing life and internal clearance as a function of ball or roller diameter, adjusted for load. Results are presented as life factors for radially loaded bearings independent of bearing size or applied load. In addition, a modified Stribeck Equation is presented that relates the maximum rolling-element load to internal bearing clearance.

Compact low power infrared tube furnace for in situ X-ray powder diffraction

NASA Astrophysics Data System (ADS)

Doran, A.; Schlicker, L.; Beavers, C. M.; Bhat, S.; Bekheet, M. F.; Gurlo, A.

2017-01-01

We describe the development and implementation of a compact, low power, infrared heated tube furnace for in situ powder X-ray diffraction experiments. Our silicon carbide (SiC) based furnace design exhibits outstanding thermal performance in terms of accuracy control and temperature ramping rates while simultaneously being easy to use, robust to abuse and, due to its small size and low power, producing minimal impact on surrounding equipment. Temperatures in air in excess of 1100 °C can be controlled at an accuracy of better than 1%, with temperature ramping rates up to 100 °C/s. The complete "add-in" device, minus power supply, fits in a cylindrical volume approximately 15 cm long and 6 cm in diameter and resides as close as 1 cm from other sensitive components of our experimental synchrotron endstation without adverse effects.

High-Temperature Helical-Tube Solar Receiver

NASA Technical Reports Server (NTRS)

Robertson, C. S., Jr.; Mccreight, L.

1984-01-01

Solar-thermal receiver used with circular parabolic concentrator to supply about 58 kW thermal power to Brayton engine or industrial process. Solar radiation focused into open end of cylindrical ceramic thermal inertial sleeve 8 in. in diameter that reradiates energy to helical heatexchanger tube surrounding sleeve.

Wetting, meniscus structure, and capillary interactions of microspheres bound to a cylindrical liquid interface.

PubMed

Kim, Paul Y; Dinsmore, Anthony D; Hoagland, David A; Russell, Thomas P

2018-03-14

Wetting, meniscus structure, and capillary interactions for polystyrene microspheres deposited on constant curvature cylindrical liquid interfaces, constructed from nonvolatile ionic or oligomeric liquids, were studied by optical interferometry and optical microscopy. The liquid interface curvature resulted from the preferential wetting of finite width lines patterned onto planar silicon substrates. Key variables included sphere diameter, nominal (or average) contact angle, and deviatoric interfacial curvature. Menisci adopted the quadrupolar symmetry anticipated by theory, with interfacial deformation closely following predicted dependences on sphere diameter and nominal contact angle. Unexpectedly, the contact angle was not constant locally around the contact line, the nominal contact angle varied among seemingly identical spheres, and the maximum interface deviation did not follow the predicted dependence on deviatoric interfacial curvature. Instead, this deviation was up to an order-of-magnitude larger than predicted. Trajectories of neighboring microspheres visually manifested quadrupole-quadrupole interactions, eventually producing square sphere packings that foreshadow interfacial assembly as a potential route to hierarchical 2D particle structures.

Microcrystalline diamond cylindrical resonators with quality-factor up to 0.5 million

NASA Astrophysics Data System (ADS)

Saito, Daisuke; Yang, Chen; Heidari, Amir; Najar, Hadi; Lin, Liwei; Horsley, David A.

2016-02-01

We demonstrate high quality-factor 1.5 mm diameter batch-fabricated microcrystalline diamond cylindrical resonators (CR) with quality-factors limited by thermoelastic damping (TED) and surface loss. Resonators were fabricated 2.6 and 5.3 μm thick in-situ boron-doped microcrystalline diamond films deposited using hot filament chemical vapor deposition. The quality-factor (Q) of as-fabricated CR's was found to increase with the resonator diameter and diamond thickness. Annealing the CRs at 700 °C in a nitrogen atmosphere led to a three-fold increase in Q, a result we attribute to thinning of the diamond layer via reaction with residual O2 in the annealing furnace. Post-anneal Q exceeding 0.5 million (528 000) was measured at the 19 kHz elliptical wineglass modes, producing a ring-down time of 8.9 s. A model for Q versus diamond thickness and resonance frequency is developed including the effects of TED and surface loss. Measured quality factors are shown to agree with the predictions of this model.

Experimental study on acoustic subwavelength imaging of holey-structured metamaterials by resonant tunneling.

PubMed

Su, Haijing; Zhou, Xiaoming; Xu, Xianchen; Hu, Gengkai

2014-04-01

A holey-structured metamaterial is proposed for near-field acoustic imaging beyond the diffraction limit. The structured lens consists of a rigid slab perforated with an array of cylindrical holes with periodically modulated diameters. Based on the effective medium approach, the structured lens is characterized by multilayered metamaterials with anisotropic dynamic mass, and an analytic model is proposed to evaluate the transmission properties of incident evanescent waves. The condition is derived for the resonant tunneling, by which evanescent waves can completely transmit through the structured lens without decaying. As an advantage of the proposed lens, the imaging frequency can be modified by the diameter modulation of internal holes without the change of the lens thickness in contrast to the lens due to the Fabry-Pérot resonant mechanism. In this experiment, the lens is assembled by aluminum plates drilled with cylindrical holes. The imaging experiment demonstrates that the designed lens can clearly distinguish two sources separated in the distance below the diffraction limit at the tunneling frequency.

Jamming of Cylindrical Grains in Featureless Vertical Channels

NASA Astrophysics Data System (ADS)

Baxter, G. William; Barr, Nicholas; Weible, Seth; Friedl, Nicholas

2013-03-01

We study jamming of low aspect-ratio cylindrical Delrin grains falling through a featureless vertical channel. With a grain height less than the grain diameter, these grains resemble aspirin tablets, poker chips, or coins. Unidisperse grains are allowed to fall under the influence of gravity through a uniform channel of square cross-section where the channel width is greater than the grain size and constant along the length of the channel. Channel widths are chosen so that no combination of grain heights and diameters is equal to the channel width. Collections of grains sometimes form jams, stable structures in which the grains are supported by the channel walls and not by grains or walls beneath them. The probability of a jam occurring and the jam's strength are influenced by the grain dimensions and channel width. We will present experimental measurements of the jamming probability and jam strength and discuss the relationship of these results to other experiments and theories. Supported by an Undergraduate Research Grant from Penn State Erie, The Behrend College

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazalova, M; Ahmad, M; Fahrig, R

Purpose: To evaluate x-ray fluorescence computed tomography induced with proton beams (pXFCT) for imaging of gold contrast agent. Methods: Proton-induced x-ray fluorescence was studied by means of Monte Carlo (MC) simulations using TOPAS, a MC code based on GEANT4. First, proton-induced K-shell and L-shell fluorescence was studied as a function of proton beam energy and 1) depth in water and 2) size of contrast object. Second, pXFCT images of a 2-cm diameter cylindrical phantom with four 5- mm diameter contrast vials and of a 20-cm diameter phantom with 1-cm diameter vials were simulated. Contrast vials were filled with water andmore » water solutions with 1-5% gold per weight. Proton beam energies were varied from 70-250MeV. pXFCT sinograms were generated based on the net number of gold K-shell or L-shell x-rays determined by interpolations from the neighboring 0.5keV energy bins of spectra collected with an idealized 4π detector. pXFCT images were reconstructed with filtered-back projection, and no attenuation correction was applied. Results: Proton induced x-ray fluorescence spectra showed very low background compared to x-ray induced fluorescence. Proton induced L-shell fluorescence had a higher cross-section compared to K-shell fluorescence. Excitation of L-shell fluorescence was most efficient for low-energy protons, i.e. at the Bragg peak. K-shell fluorescence increased with increasing proton beam energy and object size. The 2% and 5% gold contrast vials were accurately reconstructed in K-shell pXFCT images of both the 2-cm and 20-cm diameter phantoms. Small phantom L-shell pXFCT image required attenuation correction and had a higher sensitivity for 70MeV protons compared to 250MeV protons. With attenuation correction, L-shell pXFCT might be a feasible option for imaging of small size (∼2cm) objects. Imaging doses for all simulations were 5-30cGy. Conclusion: Proton induced x-ray fluorescence CT promises to be an alternative quantitative imaging technique to the commonly considered XFCT imaging with x-ray beams.« less

Launch and Functional Considerations Guiding the Scaling and Design of Rigid Inflatable Habitat Modules

NASA Astrophysics Data System (ADS)

Bell, L.

2002-01-01

The Sasakawa International Center for Space Architecture (SICSA) has a long history of projects that involve design of space structures, including habitats for low-Earth orbit (LEO) and planetary applications. Most of these facilities and component systems are planned to comply with size, geometry and mass restrictions imposed by the Space Shuttle Orbiter's payload and lift/landing abort restrictions. These constraints limit launch elements to approximately 15 ft. diameter, 40 ft. long cylindrical dimensions weighing no more than approximately 25 metric tons. It is clear that future success of commercial space programs such as tourism will hinge upon the availability of bigger and more efficient Earth to LEO launch vehicles which can greatly reduce transportation and operational costs. This will enable development and utilization of larger habitat modules and other infrastructure elements which can be deployed with fewer launches and on-orbit assembly procedures. The sizing of these new heavy lift launchers should be scaled to optimize habitat functionality and efficiency, just as the habitat designs must consider optimization of launch vehicle economy. SICSA's planning studies address these vehicle and habitat optimization priorities as parallel and interdependent considerations. The allowable diameter of habitat modules established by launch vehicle capacity dictates functionally acceptable internal configuration options. Analyses of these options relative to practical dimensions for Earth-to-orbit launch vehicle scaling were conducted for two general schemes. The "bologna slice" configuration stacks the floors within a predominately cylindrical or spherical envelope, producing circular areas. The "banana split" approach divides a cylindrical module longitudinally, creating floors that are generally rectangular in shape. The assessments established minimum sizes for reasonable utility and efficiency. The bologna slice option. This configuration is only acceptable for modules with diameters of approximately 45 ft. or more. Smaller dimensions will severely limit maximum sight lines, creating claustrophobic conditions. Equipment racks and other elements typically located around internal parameters will further reduce open areas, and vertical circulation access ways between floor levels will diminish usable space even more. However this scheme can work very well for larger diameter habitats, particularly for surface applications where a relatively wide-based/low height module is to be landed vertically. The banana split option. A longitudinal floor orientation can serve very satisfactorily for modules with diameters of 15 ft. or more. Unlike the bologna slice's circular floors, the rectangular spaces offer considerable versatility to accommodate diverse equipment and functional arrangements. Modules smaller than 15 ft. in diameter (the International Space Station standard) will be incompatible with efficient equipment rack design and layouts due to tight-radius wall curvatures. Beyond the 15 ft. diameters, it is logical to scale the modules at dimensional increments based upon the number of desired floors, allowing approximately 8-9 ft. of height/level. Current SICSA Mars mission planning advocates development of new launchers with payload accommodations for 45 ft. diameter, 200 metric ton cargo elements. This large booster will offer launch economies along with habitat scaling advantages. Launch system design efficiencies are influenced by the amount of functional drag that results as the vehicle passes through the Earth's atmosphere. These drag losses are subject to a "cubed-squared law". As the launchcraft's external dimensions increase, its surface area increases with the square of the dimension, while the volume increases with the cube. Since drag is a function of surface, not volume, increasing the vehicle size will reduce proportional drag losses. For this reason, the huge Saturn V Moon rocket experienced relatively low drag. Module pressure envelope geometries also influence internal layout versatility and functionality. SICSA examined cylindrical and spherical envelope approaches for habitat module application, exploring special advantages and disadvantages each presented. The 45 ft. diameter sphere constrained functional volumes and layouts around the upper level perimeter. A modified scheme was selected which reshaped and expanded the height of that area. SICSA's final plan proposes 45 ft. diameter modules of modified spherical form.

Bias of cylinder diameter estimation from ground-based laser scanners with different beam widths: A simulation study

NASA Astrophysics Data System (ADS)

Forsman, Mona; Börlin, Niclas; Olofsson, Kenneth; Reese, Heather; Holmgren, Johan

2018-01-01

In this study we have investigated why diameters of tree stems, which are approximately cylindrical, are often overestimated by mobile laser scanning. This paper analyzes the physical processes when using ground-based laser scanning that may contribute to a bias when estimating cylinder diameters using circle-fit methods. A laser scanner simulator was implemented and used to evaluate various properties, such as distance, cylinder diameter, and beam width of a laser scanner-cylinder system to find critical conditions. The simulation results suggest that a positive bias of the diameter estimation is expected. Furthermore, the bias follows a quadratic function of one parameter - the relative footprint, i.e., the fraction of the cylinder width illuminated by the laser beam. The quadratic signature opens up a possibility to construct a compensation model for the bias.

Wavelength dependence of the apparent diameter of retinal blood vessels

NASA Astrophysics Data System (ADS)

Park, Robert; Twietmeyer, Karen; Chipman, Russell; Beaudry, Neil; Salyer, David

2005-04-01

Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column.

Optical properties of carbon nanotubes

NASA Astrophysics Data System (ADS)

Chen, Gugang

This thesis addresses the optical properties of novel carbon filamentary nanomaterials: single-walled carbon nanotubes (SWNTs), double-walled carbon nanotubes (DWNTs), and SWNTs with interior C60 molecules ("peapods"). Optical reflectance spectra of bundled SWNTs are discussed in terms of their electronic energy band structure. An Effective Medium Model for a composite material was found to provide a reasonable description of the spectra. Furthermore, we have learned from optical absorption studies of DWNTs and C60-peapods that the host tube and the encapsulant interact weakly; small shifts in interband absorption structure were observed. Resonant Raman scattering studies on SWNTs synthesized via the HiPCO process show that the "zone-folding" approximation for phonons and electrons works reasonably well, even for small diameter (d < 1 nm) tubes. The energy of optical transitions between van Hove singularities in the electronic density of states computed from the "zone-folding" model (with gamma0 = 2.9 eV) agree well with the resonant conditions for Raman scattering. Small diameter tubes were found to exhibit additional sharp Raman bands in the frequency range 500-1200 cm-1 with an, as yet, undetermined origin. The Raman spectrum of a DWNT was found to be well described by a superposition of the Raman spectra expected for inner and outer tubes, i.e., no charge transfer occurs and the weak van der Waals (vdW) interaction between tubes does not have significant impact on the phonons. A ˜7 cm-1 downshift of the small diameter, inner-tube tangential mode frequency was observed, however, but attributed to a tube wall curvature effect, rather than the vdW interaction. Finally, we studied the chemical doping of DWNTs, where the dopant (Br anions) is chemically bound to the outside of the outer tube. The doped DWNT system is a model for a cylindrical molecular capacitor. We found experimentally that 90% of the positive charge resides on the outer tube, so that most of electric field on the inner tube is screened, i.e., we have observed a molecular Faraday cage effect. A self-consistent theoretical model in the tight-binding approximation with a classical electrostatic energy term is in good agreement with our experimental results.

Characteristics of Air Core and Surface Velocity for Water Flow in a Vortex Sediment-Extraction Chamber Measured by Using Photo Images and PTV Technique.

NASA Astrophysics Data System (ADS)

Yao, Hou Chang; Chyan Deng, Jan; Chao, Hsu Yu; Chih Yuan, Yang

2017-04-01

A vortex sediment-extraction chamber, consisted of cylindrical chamber, inflow system, bottom orifice and overflow weir, is used to separate sediment from sediment-laden water flow. A tangential inflow is introduced into a cylindrical chamber with a bottom orifice; thus, a strong vortex flow is produced there. Under actions of gravity and centrifugal force, heavier sediment particles are forced to move towards the bottom orifice, and relatively clear water flows over through the top overflow weir. The flow field in the cylindrical chamber consists of forced vortex and free vortex. When the bottom orifice is opened during the sediment-extraction process, an air core appears and changes with different settings. In this study, the air core and water surface velocity in the cylindrical chamber were measured by using a photo image process and particle tracking velocimetry (PTV), as well as numerically simulated by using a commercial software, Flow-3D.Laboratory experiments were conducted in a vortex chamber, having height of 130 cm and diameter of 48 cm. Five kinds of bottom orifice size from 1.0 cm to 3.0 cm and four kinds of inflow water discharge from 1,300cm3/s to 1,700 cm3/s were used while the inflow pipe of 3 cm in diameter was kept the same for all experiments. The characteristics of the air core and water surface velocity, and the inflow and outflow ratios under different experimental arrangements were observed and discussed so as to provide a better design and application for a vortex sediment-extraction chamber in the future.

Design of a radiation facility for very small specimens used in radiobiology studies

NASA Astrophysics Data System (ADS)

Rodriguez, Manuel; Jeraj, Robert

2008-06-01

A design of a radiation facility for very small specimens used in radiobiology is presented. This micro-irradiator has been primarily designed to irradiate partial bodies in zebrafish embryos 3-4 mm in length. A miniature x-ray, 50 kV photon beam, is used as a radiation source. The source is inserted in a cylindrical brass collimator that has a pinhole of 1.0 mm in diameter along the central axis to produce a pencil photon beam. The collimator with the source is attached underneath a computer-controlled movable table which holds the specimens. Using a 45° tilted mirror, a digital camera, connected to the computer, takes pictures of the specimen and the pinhole collimator. From the image provided by the camera, the relative distance from the specimen to the pinhole axis is calculated and coordinates are sent to the movable table to properly position the samples in the beam path. Due to its monitoring system, characteristic of the radiation beam, accuracy and precision of specimen positioning, and automatic image-based specimen recognition, this radiation facility is a suitable tool to irradiate partial bodies in zebrafish embryos, cell cultures or any other small specimen used in radiobiology research.

Self-folding polymeric containers for encapsulation and delivery of drugs

PubMed Central

Fernandes, Rohan; Gracias, David H.

2012-01-01

Self-folding broadly refers to self-assembly processes wherein thin films or interconnected planar templates curve, roll-up or fold into three dimensional (3D) structures such as cylindrical tubes, spirals, corrugated sheets or polyhedra. The process has been demonstrated with metallic, semiconducting and polymeric films and has been used to curve tubes with diameters as small as 2 nm and fold polyhedra as small as 100 nm, with a surface patterning resolution of 15 nm. Self-folding methods are important for drug delivery applications since they provide a means to realize 3D, biocompatible, all-polymeric containers with well-tailored composition, size, shape, wall thickness, porosity, surface patterns and chemistry. Self-folding is also a highly parallel process, and it is possible to encapsulate or self-load therapeutic cargo during assembly. A variety of therapeutic cargos such as small molecules, peptides, proteins, bacteria, fungi and mammalian cells have been encapsulated in self-folded polymeric containers. In this review, we focus on self-folding of all-polymeric containers. We discuss the mechanistic aspects of self-folding of polymeric containers driven by differential stresses or surface tension forces, the applications of self-folding polymers in drug delivery and we outline future challenges. PMID:22425612

Novel cryogenic sources for liquid droplet and solid filament beams

NASA Astrophysics Data System (ADS)

Grams, Michael P.

Two novel atomic and molecular beam sources have been created and tested consisting first of a superfluid helium liquid jet, and secondly a solid filament of argon. The superfluid helium apparatus is the second of its kind in the world and uses a modified liquid helium cryostat to inject a cylindrical stream of superfluid helium into vacuum through glass capillary nozzles with diameters on the order of one micron created on-site at Arizona State University. The superfluid beam is an entirely new way to study superfluid behavior, and has many new applications such as superfluid beam-surface scattering, beam-beam scattering, and boundary-free study of superfluidity. The solid beam of argon is another novel beam source created by flowing argon gas through a capillary 50 microns in diameter which is clamped by a small copper plate to a copper block kept at liquid nitrogen temperature. The gas subsequently cools and solidifies plugging the capillary. Upon heating, the solid plug melts and liquid argon exits the capillary and immediately freezes by evaporative cooling. The solid filaments may find application as wall-less cryogenic matrices, or targets for laser plasma sources of extreme UV and soft x-ray sources.

How They (Should Have) Built the Pyramids

NASA Astrophysics Data System (ADS)

Gallagher, Gregory; West, Joseph; Waters, Kevin

2014-03-01

A novel ``polygon method'' is proposed for moving large stone blocks. The method is implemented by the attachment of rods of analytically chosen radii to the block by means of rope. The chosen rods are placed on each side of the square-prism block in order to transform the square prism into a prism of higher order polygon, i.e. octagon, dodecagon etc. Experimental results are presented and compared to other methods proposed by the authors, including a dragging method and a rail method which includes the idea of dragging the block on rails made from arbitrarily chosen rod-shaped ``tracks,'' and to independent work by another group which utilized wooden attachments providing a cylindrical shape. It is found that the polygon method when used on small scale stone blocks across level open ground has an equivalent of a coefficient of friction order of 0.1. For full scale pyramid blocks, the wooden ``rods'' would need to be of order 30 cm in diameter, certainly within reason, given the diameter of wooden masts used on ships in that region during the relevant time period in Egypt. This project also inspired a ``spin-off'' project in which the behavior or rolling polygons is investigated and preliminary data is presented.

Pressure-assisted melt-filling and optical characterization of Au nano-wires in microstructured fibers.

PubMed

Lee, H W; Schmidt, M A; Russell, R F; Joly, N Y; Tyagi, H K; Uebel, P; Russell, P St J

2011-06-20

We report a novel splicing-based pressure-assisted melt-filling technique for creating metallic nanowires in hollow channels in microstructured silica fibers. Wires with diameters as small as 120 nm (typical aspect ration 50:1) could be realized at a filling pressure of 300 bar. As an example we investigate a conventional single-mode step-index fiber with a parallel gold nanowire (wire diameter 510 nm) running next to the core. Optical transmission spectra show dips at wavelengths where guided surface plasmon modes on the nanowire phase match to the glass core mode. By monitoring the side-scattered light at narrow breaks in the nanowire, the loss could be estimated. Values as low as 0.7 dB/mm were measured at resonance, corresponding to those of an ultra-long-range eigenmode of the glass-core/nanowire system. By thermal treatment the hollow channel could be collapsed controllably, permitting creation of a conical gold nanowire, the optical properties of which could be monitored by side-scattering. The reproducibility of the technique and the high optical quality of the wires suggest applications in fields such as nonlinear plasmonics, near-field scanning optical microscope tips, cylindrical polarizers, optical sensing and telecommunications.

Axially uniform resonant cavity modes for potential use in electron paramagnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Mett, Richard R.; Froncisz, Wojciech; Hyde, James S.

2001-11-01

This article is concerned with cylindrical transverse electric TE011 and rectangular TE102 microwave cavity resonators commonly used in electron paramagnetic resonance (EPR) spectroscopy. In the cylindrical mode geometry considered here, the sample is along the z axis of the cylinder, dielectric disks of 1/4 wavelength thickness are placed at each end wall, and the diameter of the cylinder is set at the cutoff condition for propagation of microwave energy in a cylindrical waveguide at the desired microwave frequency. The microwave magnetic field is exactly uniform along the sample in the region between the dielectric disks and the resonant frequency is independent of the length of the cylinder without limit. The rectangular TE102 geometry is analogous, but here the microwave magnetic field is exactly uniform in a plane. A uniform microwave field along a line sample is highly advantageous in EPR spectroscopy compared with the usual sinusoidal variation, and these geometries are called "uniform field" modes. Extensive theoretical analysis as well as finite element calculation of field patterns are presented. The perturbation of field patterns caused by sample insertion as functions of the overall length of the resonator and diameter of the sample is analyzed. The article is intended to provide a basis for design of practical structures in the range of 10 to 100 GHz.

Analysis of lunar regolith thermal energy storage

NASA Technical Reports Server (NTRS)

Colozza, Anthony J.

1991-01-01

The concept of using lunar regolith as a thermal energy storage medium was evaluated. The concept was examined by mathematically modeling the absorption and transfer of heat by the lunar regolith. Regolith thermal and physical properties were established through various sources as functions of temperature. Two cases were considered: a semi-infinite, constant temperature, cylindrical heat source embedded in a continuum of lunar regolith and a spherically shaped molten zone of lunar regolith set with an initial temperature profile. The cylindrical analysis was performed in order to examine the amount of energy which can be stored in the regolith during the day. At night, the cylinder acted as a perfect insulator. This cycling was performed until a steady state situation was reached in the surrounding regolith. It was determined that a cycling steady state occurs after approximately 15 day/night cycles. Results were obtained for cylinders of various diameters. The spherical molten zone analysis was performed to establish the amount of thermal energy, within the regolith, necessary to maintain some molten material throughout a nighttime period. This surrounding temperature profile was modeled after the cycling steady state temperature profile established by the cylindrical analysis. It was determined that a molten sphere diameter of 4.76 m is needed to maintain a core temperature near the low end of the melting temperature range throughout one nighttime period.

Explosion-Induced Implosions of Cylindrical Shell Structures

NASA Astrophysics Data System (ADS)

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

2010-11-01

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

Minimization of the hole overcut and cylindricity errors during rotary ultrasonic drilling of Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Nasr, M.; Anwar, S.; El-Tamimi, A.; Pervaiz, S.

2018-04-01

Titanium and its alloys e.g. Ti6Al4V have widespread applications in aerospace, automotive and medical industry. At the same time titanium and its alloys are regarded as difficult to machine materials due to their high strength and low thermal conductivity. Significant efforts have been dispensed to improve the accuracy of the machining processes for Ti6Al4V. The current study present the use of the rotary ultrasonic drilling (RUD) process for machining high quality holes in Ti6Al4V. The study takes into account the effects of the main RUD input parameters including spindle speed, ultrasonic power, feed rate and tool diameter on the key output responses related to the accuracy of the drilled holes including cylindricity and overcut errors. Analysis of variance (ANOVA) was employed to study the influence of the input parameters on cylindricity and overcut error. Later, regression models were developed to find the optimal set of input parameters to minimize the cylindricity and overcut errors.

Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

NASA Technical Reports Server (NTRS)

Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

2010-01-01

The future X-ray observatory missions, such as International X-ray Observatory, require grazing incidence replicated optics of extremely large collecting area (3 m2) in combination with angular resolution of less than 5 arcsec half-power diameter. The resolution of a mirror shell depends ultimately on the quality of the cylindrical mandrels from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation studies have been performed to optimize the operational parameters as well as the polishing lap configuration. Furthermore, depending upon the surface error profile, a model for localized polishing based on dwell time approach is developed. Using the inputs from the mathematical model, a mandrel, having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. We report our first experimental results and discuss plans for further improvements in the polishing process.

Optimal condition for employing an axicon-generated Bessel beam to fabricate cylindrical microlens arrays

NASA Astrophysics Data System (ADS)

Luo, Zhi; Yin, Kai; Dong, Xinran; Duan, Ji’an

2018-05-01

A numerical algorithm, modelling the transformation from a Gaussian beam to a Bessel beam, is presented for the purpose to study the optimal condition for employing an axicon-generated Bessel beam to fabricate cylindrical microlens arrays (CMLAs). By applying the numerical algorithm to simulate the spatial intensity distribution behind the axicon under different defects of a rotund-apex and different diameter ratios of an incident beam to the axicon, we find that the diffraction effects formed by the axicon edge can be almost eliminated when the diameter ratio is less than 1:2, but the spatial intensity distribution is disturbed dramatically even a few tens of microns deviation of the apex, especially for the front part of the axicon-generated Bessel beam. Fortunately, the lateral intensity profile in the rear part still maintains a desirable Bessel curve. Therefore, the rear part of the Bessel area and the less than 1:2 diameter ratio are the optimal choice for employing an axicon-generated Bessel beam to implement surface microstructures fabrication. Furthermore, by applying the optimal conditions to direct writing microstructures on fused silica with a femtosecond (fs) laser, a large area close-packed CMLA is fabricated. The CMLA presents high quality and uniformity and its optical performance is also demonstrated.

Structure and Dynamics of Polymers in Cylindrical Nanoconfinement: A Molecular Dynamics Study

NASA Astrophysics Data System (ADS)

Pressly, James; Riggleman, Robert; Winey, Karen

The structure and dynamics of polymers under nanoconfinement is critical for understanding how polymers behave in applications from hydraulic fracking to fabricating integrated circuits. We previously used simulations to explore the effect of the diameter of cylindrical pores (d = 10-40 σ, where σ is the unit length in reduced units) on polymer end-to-end distance (Ree,perp, Ree,par) , entanglement density, melt diffusion coefficient (D), and local relaxation time (τperp, τpar) at fixed polymer chain length (N = 350). These studies found D, Ree,par, and τperp increased with increasing confinement while entanglement density, Ree,perp, and τpar decreased. Experiments also found that D increased but to a lesser extent. Here, we examine the molecular weight dependence of these properties using N = 25, 50, 100, 200, 350, and 500 confined to pores of diameter 14 σ to examine a range of confinements. Our preliminary results show that as N increases D and Ree,par, increase as well, relative to the unconfined state, while entanglement density and Ree,perp decrease, consistent with our previous work. Interestingly, τ is shown to be independent of chain length indicating the impact of confinement imposed by reducing pore diameter is distinct from that imposed by increasing chain length.

Procedure for detecting underground utilities with specific shape

NASA Astrophysics Data System (ADS)

Ristic, Aleksandar; Vrtunski, Milan; Govedarica, Miro; Bugarinovic, Zeljko

2016-04-01

Nowadays GPR technology is acknowledged as a reliable, fast, non-destructive remote sensing technology whose area of applications is wider every day. One of its most common applications is underground utility detection. Not only it is possible to detect the utility in the field, but using certain algorithms utilities which haven't been detected in the field can be detected in radargrams. There is a number of procedures for automated detection of utility in the radargrams. Further, there are procedures that can estimate certain parameters such as propagation velocity, diameter or even characteristics of the material. However, the majority of these procedures is designed to detect cylindrical shape utilities, which, in a radargram, are represented with hyperbolic reflection. According to geometry of hyperbola, utility parameters can be estimated. In this paper we present a procedure that is designed to estimate characteristics of non-cylindrical utilities. It is worth mentioning that these utilities are not so rare. Some underground tanks and sewage collectors are among them. Heat line is consisted of two insulated pipes of the same diameter, often placed in a concrete channel and covered with plates made from reinforced concrete. Therefore, it can be considered as non-cylindrical utility and such structure has characteristic signature in a radargram. The main idea of the proposed procedure is to detect this signature, and then, based on standardized parameters for the heat lines, to estimate the diameter of the pipes. The proposed procedure is based on artificial neural network. As a training set we made a number of radargrams collected on different locations which contain heat lines of various dimensions. Pipe diameters were in a range from 65 to 250 mm. 400MHz antenna was used since the depth hasn't exceeded 2m. After the network is trained it is validated using radargrams that haven't been used in the training set. Further tests were done with radargrams that contained none, one or several heat lines. Experiments showed that it is possible to automatically detect heating lines in a radargram and later, based on detection results, to estimate the diameter of the pipes using standard heat line dimensions. This paper is a contribution to the 2016 EGU GA Session GI3.1 "Civil Engineering Applications of Ground Penetrating Radar," organized by the COST Action TU1208

TU-CD-207-10: Dedicated Cone-Beam Breast CT: Design of a 3-D Beam-Shaping Filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vedantham, S; Shi, L; Karellas, A

2015-06-15

Purpose: To design a 3 -D beam-shaping filter for cone-beam breast CT for equalizing x-ray photon fluence incident on the detector along both fan and cone angle directions. Methods: The 3-D beam-shaping filter was designed as the sum of two filters: a bow-tie filter assuming cylindrical breast and a 3D difference filter equivalent to the difference in projected thickness between the cylinder and the real breast. Both filters were designed with breast-equivalent material and converted to Al for the targeted x-ray spectrum. The bow-tie was designed for the largest diameter cylindrical breast by determining the fan-angle dependent path-length and themore » filter thickness needed to equalize the fluence. A total of 23,760 projections (180 projections of 132 binary breast CT volumes) were averaged, scaled for the largest breast, and subtracted from the projection of the largest diameter cylindrical breast to provide the 3D difference filter. The 3 -D beam shaping filter was obtained by summing the two filters. Numerical simulations with semi-ellipsoidal breasts of 10–18 cm diameter (chest-wall to nipple length=0.75 x diameter) were conducted to evaluate beam equalization. Results: The proposed 3-D beam-shaping filter showed a 140% -300% improvement in equalizing the photon fluence along the chest-wall to nipple (cone-angle) direction compared to a bow-tie filter. The improvement over bow-tie filter was larger for breasts with longer chest-wall to nipple length. Along the radial (fan-angle) direction, the performance of the 3-D beam shaping filter was marginally better than the bow-tie filter, with 4%-10% improvement in equalizing the photon fluence. For a ray traversing the chest-wall diameter of the breast, the filter transmission ratio was >0.95. Conclusion: The 3-D beam shaping filter provided substantial advantage over bow-tie filter in equalizing the photon fluence along the cone-angle direction. In conjunction with a 2-axis positioner, the filter can accommodate breasts of varying dimensions and chest-wall inclusion. Supported in part by NIH R01 CA128906 and R21 CA134128. The contents are solely the responsibility of the authors and do not reflect the official views of the NIH or NCI.« less

Preliminary results from the Small Negative Ion Facility (SNIF) at CCFE

NASA Astrophysics Data System (ADS)

Zacks, J.; McAdams, R.; Booth, J.; Flinders, K.; Holmes, A. J. T.; Simmonds, M.; Stevens, B.; Stevenson, P.; Surrey, E.; Warder, S.; Whitehead, A.; Young, D.

2013-02-01

At Culham Centre for Fusion Energy, a new beam extraction test facility has been built with the purpose of studying and enhancing negative ion beam production and transport. The multipole hydrogen ion source is based on a RF generated plasma using a continuous 5kW power supply operating at the industrial standard frequency of 13.56MHz. The cylindrical source has a diameter of 30cm and a depth of 20cm, with a flat spiral antenna driving the source through a quartz window. The magnet configuration is arranged to produce a dipole filter field across the ion source close to the plasma grid. The plasma load is matched to the RF generator using a Pi matching network. The accelerator uses a single extraction aperture of 14mm diameter, with a biased insert for electron suppression. The accelerator is a triode design with a beam energy of up to 30kV. The beamline consists of a turbomolecular pumped vacuum tank with an instrumented beam dump and ports for additional diagnostics. The ITER Neutral Beam source operates with the enhancement of caesium, which, when scaled up to a reactor, will be heavily consumed. The small size of SNIF allows for fast turn around of modifications and alternative materials to caesium can be tested. A full description of the facility and planned diagnostics is given. Initial results are presented, including measurements and calculations of the plasma load on the RF generator, and beam extraction measurements.

Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT-CT scanners

PubMed Central

DiFilippo, Frank P.

2008-01-01

A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners. PMID:18635899

Fluidic assembly for an ultra-high-speed chromosome flow sorter

DOEpatents

Gray, Joe W.; Alger, Terry W.; Lord, David E.

1982-01-01

A fluidic assembly for an ultra-high-speed chromosome flow sorter using a fluid drive system, a nozzle with an orifice having a small ratio of length to diameter, and mechanism for vibrating the nozzle along its axis at high frequencies. The orifice is provided with a sharp edge at its inlet, and a conical section at its outlet for a transition from a short cylindrical aperture of small length to diameter ratio to free space. Sample and sheath fluids in separate low pressure reservoirs are transferred into separate high pressure buffer reservoirs through a valve arrangement which first permit the fluids to be loaded into the buffer reservoirs under low pressure. Once loaded, the buffer reservoirs are subjected to high pressure and valves are operated to permit the buffer reservoirs to be emptied through the nozzle under high pressure. A sensor and decision logic is positioned at the exit of the nozzle, and a charging pulse is applied to the jet when a particle reaches a position further downstream where the droplets are formed. In order to adjust the timing of charge pulses, the distance between the sensing station at the outlet of the nozzle and the droplet breakoff point is determined by stroboscopic illumination of the droplet breakoff region using a laser and a revolving lucite cylinder, and a beam on/off modulator. The breakoff point in the region thus illuminated may then be viewed, using a television monitor.

Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT CT scanners

NASA Astrophysics Data System (ADS)

Di Filippo, Frank P.

2008-08-01

A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high-resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners.

Masses of Fluid for Cylindrical Tanks in Rock With Partial Uplift of Bottom Plate

PubMed Central

Taniguchi, Tomoyo; Katayama, Yukihiro

2016-01-01

This study proposes the use of a slice model consisting of a set of thin rectangular tanks for evaluating the masses of fluid contributing to the rocking motion of cylindrical tanks; the effective mass of fluid for rocking motion, that for rocking–bulging interaction, effective moment inertia of fluid for rocking motion and its centroid. They are mathematically or numerically quantified, normalized, tabulated, and depicted as functions of the aspect of tanks for different values of the ratio of the uplift width of the tank bottom plate to the diameter of tank for the designer's convenience. PMID:27303110

Effect of multiply charged ions on the performance and beam characteristics in annular and cylindrical type Hall thruster plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Holak; Lim, Youbong; Choe, Wonho, E-mail: wchoe@kaist.ac.kr

2014-10-06

Plasma plume and thruster performance characteristics associated with multiply charged ions in a cylindrical type Hall thruster (CHT) and an annular type Hall thruster are compared under identical conditions such as channel diameter, channel depth, propellant mass flow rate. A high propellant utilization in a CHT is caused by a high ionization rate, which brings about large multiply charged ions. Ion currents and utilizations are much different due to the presence of multiply charged ions. A high multiply charged ion fraction and a high ionization rate in the CHT result in a higher specific impulse, thrust, and discharge current.

A 6-GW NEODYMIUM GLASS LASER,

DTIC Science & Technology

A 6-GW neodymium glass laser with a simple phototropic Q-switch is described. The laser consists of three cylindrical rods in series, each 250 mm...operation (50-80 microsec. repetition frequency), the total output was 200 j. The use of a phototropic liquid switch and large-diameter neodymium glass

Analytical model for vibration prediction of two parallel tunnels in a full-space

NASA Astrophysics Data System (ADS)

He, Chao; Zhou, Shunhua; Guo, Peijun; Di, Honggui; Zhang, Xiaohui

2018-06-01

This paper presents a three-dimensional analytical model for the prediction of ground vibrations from two parallel tunnels embedded in a full-space. The two tunnels are modelled as cylindrical shells of infinite length, and the surrounding soil is modelled as a full-space with two cylindrical cavities. A virtual interface is introduced to divide the soil into the right layer and the left layer. By transforming the cylindrical waves into the plane waves, the solution of wave propagation in the full-space with two cylindrical cavities is obtained. The transformations from the plane waves to cylindrical waves are then used to satisfy the boundary conditions on the tunnel-soil interfaces. The proposed model provides a highly efficient tool to predict the ground vibration induced by the underground railway, which accounts for the dynamic interaction between neighbouring tunnels. Analysis of the vibration fields produced over a range of frequencies and soil properties is conducted. When the distance between the two tunnels is smaller than three times the tunnel diameter, the interaction between neighbouring tunnels is highly significant, at times in the order of 20 dB. It is necessary to consider the interaction between neighbouring tunnels for the prediction of ground vibrations induced underground railways.

Study of the turbocharger shaft motion by means of infrared sensors

NASA Astrophysics Data System (ADS)

Serrano, J. R.; Guardiola, C.; Dolz, V.; López, M. A.; Bouffaud, F.

2015-05-01

This work describes a technique for measuring the precession movement of the shaft of small automotive turbochargers. The main novelty is that the technique is based on infrared light diode sensors. With presented technique it is possible to perform secure mounting of electronics and also to measure, with good accuracy, far enough from the turbocharger shaft. Both advantages allow applying it even in critical lubrication conditions and when blade contact occurs. The technique's main difficulties arise from the small size of the turbocharger shaft and the high precession movement in critical conditions. In order to generate the optimum albedo reflection for infrared measurement, a special cylindrical nut with larger diameter than the original one is assembled at the shaft tip in the compressor side. Following, shaft balancing, the calibration of the sensors and the compensation of errors from different sources are needed steps before the method is able to identify the main frequencies of shaft motion. Once synchronous and sub-synchronous frequencies have been obtained it is possible to reconstruct the instantaneous position of the shaft to determine its precession movement.

Determination by Small-angle X-ray Scattering of Pore Size Distribution in Nanoporous Track-etched Polycarbonate Membranes

NASA Astrophysics Data System (ADS)

Jonas, A. M.; Legras, R.; Ferain, E.

1998-03-01

Nanoporous track-etched membranes with narrow pore size distributions and average pore size diameters tunable from 100 to 1000 Åare produced by the chemical etching of latent tracks in polymer films after irradiation by a beam of accelerated heavy ions. Nanoporous membranes are used for highly demanding filtration purposes, or as templates to obtain metallic or polymeric nanowires (L. Piraux et al., Nucl. Instr. Meth. Phys. Res. 1997, B131, 357). Such applications call for developments in nanopore size characterization techniques. In this respect, we report on the characterization by small-angle X-ray scattering (SAXS) of nanopore size distribution (nPSD) in polycarbonate track-etched membranes. The obtention of nPSD requires inverting an ill-conditioned inhomogeneous equation. We present different numerical routes to overcome the amplification of experimental errors in the resulting solutions, including a regularization technique allowing to obtain the nPSD without a priori knowledge of its shape. The effect of deviations from cylindrical pore shape on the resulting distributions are analyzed. Finally, SAXS results are compared to results obtained by electron microscopy and conductometry.

Weakly nonlinear incompressible Rayleigh-Taylor instability growth at cylindrically convergent interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, L. F.; He, X. T.; HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871

2013-04-15

A weakly nonlinear (WN) model has been developed for the incompressible Rayleigh-Taylor instability (RTI) in cylindrical geometry. The transition from linear to nonlinear growth is analytically investigated via a third-order solutions for the cylindrical RTI initiated by a single-mode velocity perturbation. The third-order solutions can depict the early stage of the interface asymmetry due to the bubble-spike formation, as well as the saturation of the linear (exponential) growth of the fundamental mode. The WN results in planar RTI [Wang et al., Phys. Plasmas 19, 112706 (2012)] are recovered in the limit of high-mode number perturbations. The difference between the WNmore » growth of the RTI in cylindrical geometry and in planar geometry is discussed. It is found that the interface of the inward (outward) development spike/bubble is extruded (stretched) by the additional inertial force in cylindrical geometry compared with that in planar geometry. For interfaces with small density ratios, the inward growth bubble can grow fast than the outward growth spike in cylindrical RTI. Moreover, a reduced formula is proposed to describe the WN growth of the RTI in cylindrical geometry with an acceptable precision, especially for small-amplitude perturbations. Using the reduced formula, the nonlinear saturation amplitude of the fundamental mode and the phases of the Fourier harmonics are studied. Thus, it should be included in applications where converging geometry effects play an important role, such as the supernova explosions and inertial confinement fusion implosions.« less

SU-F-18C-11: Diameter Dependency of the Radial Dose Distribution in a Long Polyethylene Cylinder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakalyar, D; McKenney, S; Feng, W

Purpose: The radial dose distribution in the central plane of a long cylinder following a long CT scan depends upon the diameter and composition of the cylinder. An understanding of this behavior is required for determining the spatial average of the dose in the central plane. Polyethylene, the material for construction of the TG200/ICRU phantom (30 cm in diameter) was used for this study. Size effects are germane to the principles incorporated in size specific dose estimates (SSDE); thus diameter dependency was explored as well. Method: ssuming a uniform cylinder and cylindrically symmetric conditions of irradiation, the dose distribution canmore » be described using a radial function. This function must be an even function of the radial distance due to the conditions of symmetry. Two effects are accounted for: The direct beam makes its weakest contribution at the center while the contribution due to scatter is strongest at the center and drops off abruptly at the outer radius. An analytic function incorporating these features was fit to Monte Carlo results determined for infinite polyethylene cylinders of various diameters. A further feature of this function is that it is integrable. Results: Symmetry and continuity dictate a local extremum at the center which is a minimum for the larger sizes. The competing effects described above can Resultin an absolute maximum occurring between the center and outer edge of the cylinders. For the smallest cylinders, the maximum dose may occur at the center. Conclusion: An integrable, analytic function can be used to characterize the radial dependency of dose for cylindrical CT phantoms of various sizes. One use for this is to help determine average dose distribution over the central cylinder plane when equilibrium dose has been reached.« less

Two dimensional cylindrical fast magnetoacoustic solitary waves in a dust plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Haifeng; Wang Shiqing; Engineering and Technical College of Chengdu University of Technology, Leshan 614000

2011-04-15

The nonlinear fast magnetoacoustic solitary waves in a dust plasma with the combined effects of bounded cylindrical geometry and transverse perturbation are investigated in a new equation. In this regard, cylindrical Kadomtsev-Petviashvili (CKP) equation is derived using the small amplitude perturbation expansion method. Under a suitable coordinate transformation, the CKP equation can be solved analytically. It is shown that the dust cylindrical fast magnetoacoustic solitary waves can exist in the CKP equation. The present investigation may have relevance in the study of nonlinear electromagnetic soliton waves both in laboratory and astrophysical plasmas.

Formation of hexagonal boron nitride nanoscrolls induced by inclusion and exclusion of self-assembling molecules in solution process.

PubMed

Hwang, Da Young; Suh, Dong Hack

2014-06-07

Unlike nanoscrolls of 2D graphene, those of 2D h-BN have not been demonstrated, except for only a few experimental reports. Nanoscrolls of h-BN with high yields and reproducibility are first synthesized by a simple solution process. Inner-tube diameters of BNSs including LCAs, N-(2-aminoethyl)-3α-hydroxy-5β-cholan-24-amide, a bile acid derivative and self-assembling material, can be controlled by adjusting the diameter of the LCA fiber which is grown by self-assembly. TEM and SEM images show that BNSs have a tube-like morphology and the inner-tube diameter of BNSs can be controlled in the range from 20 to 60 nm for a smaller diameter, up to 300 nm for a larger diameter by LCA fiber growth inside the BNSs. Finally, open cylindrical BNSs with hollow cores were obtained by dissolving LCAs inside BNSs.

Design And Commissioning Status Of New Cylindrical HiPIMS Nb Coating System for SRF Cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, H. Lawrence; Macha, Kurt M.; Valente-Feliciano, Anne-Marie

2014-02-01

For the past 19 years Jefferson Lab has sustained a program studying niobium films deposited on small samples in order to develop an understanding of the correlation between deposition parameters, film micro-structure, and RF performance. A new cavity deposition system employing a cylindrical cathode using the HiPIMS technique has been developed to apply this work to cylindrical cavities. The status of this system will be presented.

Elasto-plastic impact of hemispherical shell impacting on hard rigid sphere

NASA Technical Reports Server (NTRS)

Raftopoulos, D. D.; Spicer, A. L.

1976-01-01

An analysis of plastic stress waves for cylindrical metallic projectile in impact is extended to an analysis of a hemispherical shell suffereing plastic deformation during the process of impact. It is assumed that the hemispherical shell with a prescribed launch velocity impinges a fixed rigid sphere of diameter equal to the internal diameter of the shell. The dynamic biaxial state of stress present in the shell during deformation is investigated. The analysis is valuable for studying the state of stress during large plastic deformation of a hemispherical shell.

JACKETED FISSIONABLE MEMBER

DOEpatents

Boller, E.R.; Robinson, J.W.

1960-09-13

A fuel element design for a nuclear reactor is presented. The fuel element comprises a cylindrical fuel body having a portion of smaller diameter at each end thereof with an annular flange at the extreme ends of these portions of smaller diameter. An end cap fits over the ends of the fuel body and has an internal annular groove adapted to receive the flange. The fuel body and end caps are disposed in a cup-shaped jacket, a closure disc completing the enclosure of the fuel body, and tht caps are bonded over their entire periphery to the jacket.

Transgressive reef sequences of the Devonian Devils Gate Limestone, Red Hill, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shapiro, R.; Dehler, C.; Flynn, J.

The Devils Gate Limestone at Red Hill, Simpson Park Range, Eureka Co., Nevada is composed of several conformable transgressive sequences cropping out in a series of step-like cliffs 1--5 m high. The general sequence is as follows: (1) a 1--4 m thick in situ boundstone dominated by large, period rugosans, domical and stratiform stromatoporids and rare, 1--3 cm diameter oncolites. Most of the boundstone is composed of small, cylindrical fossils. Petrographic observation revealed them to be mostly Amphipora and Cladopora. The upper portions of these units are packstones composed of Amphipora/Cladopora and, to a lesser degree, small favositids, round stromatoporoidsmore » (3--4 cm diameter), and rip-up clasts. (2) These beds grade upward into a thinly laminated and/or cross-bedded unfossiliferous mudstone. (3) Stratigraphically above the mudstone or in contact with the packstone, is a cross-bedded and/or bioturbated wackestone containing fossils no greater than 2 mm. In thin section, the mottled reddish-grey wackestone is pelletal, with rare lenses of small crinoid columnals. Disarticulated brachiopod shells of low diversity are found near the tops of some of these layers. Community dominance in the reefal units alternates between Amphipora/Cladopora, colonial rugose, and stromatoporoids. Oncolite mounds are common in the uppermost unit. The typical reef succession consists of domical and digitate stromatoporoids growing on the upper surfaces of in place or disturbed, large rugosans, though the reverse has been noted. Tabulate corals encrusted by stromatoporoids are often found in the packstone. It is important to note that often these successions' can be attributed to juxtaposition along styolites.« less

Thermal convection of liquid metal in a long inclined cylinder

NASA Astrophysics Data System (ADS)

Teimurazov, Andrei; Frick, Peter

2017-11-01

The turbulent convection of low-Prandtl-number fluids (Pr=0.0083 ) in a long cylindrical cell, heated at one end face and cooled at the other, inclined to the vertical at angle β , 0 ≤β ≤π /2 with step π /20 , is studied numerically by solving the Oberbeck-Boussinesq equations with the large-eddy-simulation approach for small-scale turbulence. The cylinder length is L =5 D , where D is the diameter. The Rayleigh number, determined by the cylinder diameter, is of the order of 5 ×106 . We show that the structure of the flow strongly depends on the inclination angle. A stable large-scale circulation (LSC) slightly disturbed by small-scale turbulence exists in the horizontal cylinder. The deviation from a horizontal position provides strong amplification of both LSC and small-scale turbulence. The energy of turbulent pulsations increases monotonically with decreasing inclination angle β , matching the energy of the LSC at β ≈π /5 . The intensity of the LSC has a wide, almost flat, maximum for an inclined cylinder and slumps approaching the vertical position, in which the LSC vanishes. The dependence of the Nusselt number on the inclination angle has a maximum at β ≈7 π /20 and generally follows the dependence of the intensity of LSC on the inclination. This indicates that the total heat transport is highly determined by LSC. We examine the applicability of idealized thermal boundary conditions (BCs) for modeling a real experiment with liquid sodium flows. Therefore, the simulations are done with two types of temperature BCs: fixed face temperature and fixed heat flux. The intensity of the LSC is slightly higher in the latter case and leads to a corresponding increase of the Nusselt number and enhancement of temperature pulsations.

SMALL-ANGLE NEUTRON SCATTERING CHARACTERIZATION OF THE STRUCTURE OF NANOPOROUS CARBONS FOR ENERGY-RELATED APPLICATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Lilin; Mavila Chathoth, Suresh; Melnichenko, Yuri B

2011-01-01

We used small-angle neutron scattering (SANS) and neutron contrast variation to study the structure of four nanoporouscarbons prepared by thermo-chemical etching of titanium carbide TiC in chlorine at 300, 400, 600, and 800 C with pore diameters ranging between -4 and -11 {angstrom}. SANS patterns were obtained from dry samples and samples saturated with deuterium oxide (D{sub 2}O) in order to delineate origin of the power law scattering in the low Q domain as well as to evaluate pore accessibility for D{sub 2}O molecules. SANS cross section of all samples was fitted to Debye-Anderson-Brumberger (DAB), DAB-Kirste-Porod models as well asmore » to the Guinier and modified Guinier formulae for cylindrical objects, which allowed for evaluating the radii of gyration as well as the radii and lengths of the pores under cylindrical shape approximation. SANS data from D{sub 2}O-saturated samples indicate that strong upturn in the low Q limit usually observed in the scattering patterns from microporous carbon powders is due to the scattering from outer surface of the powder particles. Micropores are only partially filled with D{sub 2}O molecules due to geometrical constraints and or partial hydrophobicity of the carbon matrix. Structural parameters of the dry carbons obtained using SANS are compared with the results of the gas sorption measurements and the values agree for carbide-derived carbons (CDCs) obtained at high chlorination temperatures (>600 C). For lower chlorination temperatures, pore radii obtained from gas sorption overestimate the actual pore size as calculated from SANS for two reasons: inaccessible small pores are present and the model-dependent fitting based on density functional theory models assumes non-spherical pores, whereas SANS clearly indicates that the pore shape in microporous CDC obtained at low chlorination temperatures is nearly spherical.« less

Bifurcation parameters of a reflected shock wave in cylindrical channels of different roughnesses

NASA Astrophysics Data System (ADS)

Penyazkov, O.; Skilandz, A.

2018-03-01

To investigate the effect of bifurcation on the induction time in cylindrical shock tubes used for chemical kinetic experiments, one should know the parameters of the bifurcation structure of a reflected shock wave. The dynamics and parameters of the shock wave bifurcation, which are caused by reflected shock wave-boundary layer interactions, are studied experimentally in argon, in air, and in a hydrogen-nitrogen mixture for Mach numbers M = 1.3-3.5 in a 76-mm-diameter shock tube without any ramp. Measurements were taken at a constant gas density behind the reflected shock wave. Over a wide range of experimental conditions, we studied the axial projection of the oblique shock wave and the pressure distribution in the vicinity of the triple Mach configuration at 50, 150, and 250 mm from the endwall, using side-wall schlieren and pressure measurements. Experiments on a polished shock tube and a shock tube with a surface roughness of 20 {μ }m Ra were carried out. The surface roughness was used for initiating small-scale turbulence in the boundary layer behind the incident shock wave. The effect of small-scale turbulence on the homogenization of the transition zone from the laminar to turbulent boundary layer along the shock tube perimeter was assessed, assuming its influence on a subsequent stabilization of the bifurcation structure size versus incident shock wave Mach number, as well as local flow parameters behind the reflected shock wave. The influence of surface roughness on the bifurcation development and pressure fluctuations near the wall, as well as on the Mach number, at which the bifurcation first develops, was analyzed. It was found that even small additional surface roughness can lead to an overshoot in pressure growth by a factor of two, but it can stabilize the bifurcation structure along the shock tube perimeter.

Using the DP-190 glue for adhesive attachment of a large space mirror and its rim

NASA Astrophysics Data System (ADS)

Vlasenko, Oleg; Zverev, Alexey; Sachkov, Mikhail

2014-07-01

The glue DP-190 is widely used for adhesive attachment of astrositall (zerodur) lightweight large-size space astronomical mirrors (diameter of 1.7 m and more) with elements of their frames of invar. Peculiarities of physicalmechanical behavior of the glue DP-190 when exposed to the environment during the ground operation and in orbit cause instability of the reflective surface quality of mirrors. In this report we show that even a small (around 1%-5%) volumetric deformation of a cylindrical adhesive layer with a thickness of 0.8 mm between the mirror and the rim element causes significant mirrors deformation. We propose to use adhesive layer of special form that allows to reduce volumetric deformations of the glue DP-190 up to three times. Here we present results based on primary mirror tests of the WSO-UV project.

Development of a vector-tensor system to measure the absolute magnetic flux density and its gradient in magnetically shielded rooms.

PubMed

Voigt, J; Knappe-Grüneberg, S; Gutkelch, D; Haueisen, J; Neuber, S; Schnabel, A; Burghoff, M

2015-05-01

Several experiments in fundamental physics demand an environment of very low, homogeneous, and stable magnetic fields. For the magnetic characterization of such environments, we present a portable SQUID system that measures the absolute magnetic flux density vector and the gradient tensor. This vector-tensor system contains 13 integrated low-critical temperature (LTc) superconducting quantum interference devices (SQUIDs) inside a small cylindrical liquid helium Dewar with a height of 31 cm and 37 cm in diameter. The achievable resolution depends on the flux density of the field under investigation and its temporal drift. Inside a seven-layer mu-metal shield, an accuracy better than ±23 pT for the components of the static magnetic field vector and ±2 pT/cm for each of the nine components of the gradient tensor is reached by using the shifting method.

Development of a vector-tensor system to measure the absolute magnetic flux density and its gradient in magnetically shielded rooms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voigt, J.; Knappe-Grüneberg, S.; Gutkelch, D.

2015-05-15

Several experiments in fundamental physics demand an environment of very low, homogeneous, and stable magnetic fields. For the magnetic characterization of such environments, we present a portable SQUID system that measures the absolute magnetic flux density vector and the gradient tensor. This vector-tensor system contains 13 integrated low-critical temperature (LTc) superconducting quantum interference devices (SQUIDs) inside a small cylindrical liquid helium Dewar with a height of 31 cm and 37 cm in diameter. The achievable resolution depends on the flux density of the field under investigation and its temporal drift. Inside a seven-layer mu-metal shield, an accuracy better than ±23more » pT for the components of the static magnetic field vector and ±2 pT/cm for each of the nine components of the gradient tensor is reached by using the shifting method.« less

LSSA large area silicon sheet task continuous Czochralski process development

NASA Technical Reports Server (NTRS)

Rea, S. N.

1978-01-01

A Czochralski crystal growing furnace was converted to a continuous growth facility by installation of a premelter to provide molten silicon flow into the primary crucible. The basic furnace is operational and several trial crystals were grown in the batch mode. Numerous premelter configurations were tested both in laboratory-scale equipment as well as in the actual furnace. The best arrangement tested to date is a vertical, cylindrical graphite heater containing small fused silicon test tube liner in which the incoming silicon is melted and flows into the primary crucible. Economic modeling of the continuous Czochralski process indicates that for 10 cm diameter crystal, 100 kg furnace runs of four or five crystals each are near-optimal. Costs tend to asymptote at the 100 kg level so little additional cost improvement occurs at larger runs. For these conditions, crystal cost in equivalent wafer area of around $20/sq m exclusive of polysilicon and slicing was obtained.

Hugoniot Measurements at Low Pressures in Tin Using 800 MeV proton Radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, Cynthia; Hogan, Gary E; King, Nicholas S. P.

2009-08-05

A 2cm long 8 mm diameter cylindrical tin target has been shocked to a pressure in the region of the {beta} {yields} {gamma} phase change using a small, low density PETN charge mounted on the opposite side of a stainless steel diaphragm. The density jump and shock velocity were measured radiographically as the shock wave moved through the sample and the pressure dropped, using the proton radiography facility at LANL. This provided a quasi-continuous record of the equations of state along the Hugoniot for the P1 wave from a shock velocity of 3.25 km/sec down to near the sound speed.more » Edge release effects were removed from the data using tomographic techniques. The data show evidence for a phase transition that extends over a broad pressure range. The data and analysis will be presented.« less

Design, fabrication, and test of lightweight shell structure, phase 2

NASA Technical Reports Server (NTRS)

1974-01-01

A cylindrical shell skirt structure 4.57 m (180 in.) in diameter and 3.66 m (144 in.) high was subjected to a design and analysis study using a wide variety of structural materials and concepts. The design loading of 1225.8 N/cm (700 lb/in.) axial compression and 245.2 N/cm (140 lb/in.) torsion is representative of that expected on a typical space tug skirt section. Structural concepts evaluated included honeycomb sandwich, truss, isogrid, and skin/stringer/frame. The materials considered included a wide variety of structural metals as well as glass, graphite, and boron-reinforced composites. The most unique characteristic of the candidate designs is that they involve the use of very thin-gage material. Fabrication and structural test of small panels and components representative of many of the candidate designs served to demonstrate proposed fabrication techniques and to verify design and analysis methods.

An experimental study of the transient regime to fluidized chimney in a granular medium

NASA Astrophysics Data System (ADS)

Philippe, Pierre; Mena, Sarah; Brunier-Coulin, Florian; Curtis, Jennifer

2017-06-01

Localized fluidization within a granular packing along an almost cylindrical chimney is observed when an upward fluid-flow, injected through a small port diameter, exceeds a critical flow-rate. Once this threshold reached, a fluidized area is first initiated in the close vicinity of the injection hole before gradually growing upward to the top surface of the granular layer. In this work, we present an experimental investigation specifically dedicated to the kinetics of chimney fluidization in an immersed granular bed. Two different transient regimes are identified depending on wether the expansion of the fluidized area is rather fast and regular, reaching the final chimney state typically in less than 10 seconds, or, on the contrary, slow and very progressively accelerated, giving rise to transient duration up to 1 hour or even more. Some systematic investigations allow to propose several empirical scaling relations for the kinetics of chimney fluidization in the fast regular regime.

TECHNICAL NOTE: High-speed grinding using thin abrasive disks for microcomponents

NASA Astrophysics Data System (ADS)

Yeo, S. H.; Balon, S. A. P.

2002-01-01

This paper introduces the development of a high-speed grinding device for cylindrical grinding of microcomponents made of hard and brittle materials. The study made use of an ultraprecision diamond turning machine tool as a basic platform. The novelty of the device is based on the high-speed air bearing spindle with a thin grinding wheel, similar to the dicing technology for silicon wafer fabrication. The spindle attachment is inclined at an angle to the main spindle which holds the precision fixture mechanism via the vacuum chuck. Experiments have been conducted to verify the design and implementation of the grinding methodology. A feature size as small as 31 μm in diameter and average surface roughness of 98 nm were obtained in the experimental work. It is found that the work done is capable of manufacturing miniature components, such as microcylindrical stepped shafts.

Design and fabrication of 55-gallon drum shuffler standards

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, S.M.; Hsue, F.; Hoth, C.

1994-08-01

To analyze waste with varying levels of nuclear material, suitable standards are needed to calibrate analytical instrumentation. At the Los Alamos Plutonium Facility, the authors have designed and fabricated a single drum standard for a passive-active neutron counter (shuffler). The standard is modified simply by adding or subtracting plutonium of uranium cylinders to adapt to a range of nuclear material. The plutonium or uranium oxide was placed into small cylindrical containers (1-in. diameter by 5-in. long) and diluted with diatomaceous earth. The cylinders were welded closed and removed from the glove box environment without any external contamination. The containers weremore » leak tested and then placed on a segmented gamma scanner to assure homogeneous distribution of the nuclear material. The cylinders are now placed into the drum to achieve the needed ranges for calibration of the instruments.« less

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

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

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

Improvement of film cooling effectiveness with a small downstream block body

NASA Astrophysics Data System (ADS)

Khorsi, A.; Guelailia, A.; Hamidou, M. K.

2016-07-01

The aim of this study is to predict the improvement in film cooling performance over a flat plate through a single row of cylindrical holes with different streamwise angles by using the Ansys CFX software package. In order to improve the film cooling effectiveness, a short crescent-shaped block is placed downstream of a cylindrical cooling hole. The numerical results of the cylindrical hole without the downstream short crescent-shaped block are compared with experimental data.

Experimental investigation of the effect of air cavity size in cylindrical ionization chambers on the measurements in 60Co radiotherapy beams

NASA Astrophysics Data System (ADS)

Swanpalmer, John; Johansson, Karl-Axel

2011-11-01

In the late 1970s, Johansson et al (1978 Int. Symp. National and International Standardization of Radiation Dosimetry (Atlanta 1977) vol 2 (Vienna: IAEA) pp 243-70) reported experimentally determined displacement correction factors (pdis) for cylindrical ionization chamber dosimetry in 60Co and high-energy photon beams. These pdis factors have been implemented and are currently in use in a number of dosimetry protocols. However, the accuracy of these factors has recently been questioned by Wang and Rogers (2009a Phys. Med. Biol. 54 1609-20), who performed Monte Carlo simulations of the experiments performed by Johansson et al. They reported that the inaccuracy of the pdis factors originated from the normalization procedure used by Johansson et al. In their experiments, Johansson et al normalized the measured depth-ionization curves at the depth of maximum ionization for each of the different ionization chambers. In this study, we experimentally investigated the effect of air cavity size of cylindrical ionization chambers in a PMMA phantom and 60Co γ-beam. Two different pairs of air-filled cylindrical ionization chambers were used. The chambers in each pair had identical construction and materials but different air cavity volume (diameter). A 20 MeV electron beam was utilized to determine the ratio of the mass of air in the cavity of the two chambers in each pair. This ratio of the mass of air in each pair was then used to compare the ratios of the ionizations obtained at different depths in the PMMA phantom and 60Co γ-beam using the two pairs of chambers. The diameter of the air cavity of cylindrical ionization chambers influences both the depth at which the maximum ionization is observed and the ionization per unit mass of air at this depth. The correction determined at depths of 50 mm and 100 mm is smaller than the correction currently used in many dosimetry protocols. The results presented here agree with the findings of Wang and Rogers' Monte Carlo simulations and show that the normalization procedure employed by Johansson et al is not correct.

Propagation properties of cylindrical sinc Gaussian beam

NASA Astrophysics Data System (ADS)

Eyyuboğlu, Halil T.; Bayraktar, Mert

2016-09-01

We investigate the propagation properties of cylindrical sinc Gaussian beam in turbulent atmosphere. Since an analytic solution is hardly derivable, the study is carried out with the aid of random phase screens. Evolutions of the beam intensity profile, beam size and kurtosis parameter are analysed. It is found that on the source plane, cylindrical sinc Gaussian beam has a dark hollow appearance, where the side lobes also start to emerge with increase in width parameter and Gaussian source size. During propagation, beams with small width and Gaussian source size exhibit off-axis behaviour, losing the dark hollow shape, accumulating the intensity asymmetrically on one side, whereas those with large width and Gaussian source size retain dark hollow appearance even at long propagation distances. It is seen that the beams with large widths expand more in beam size than the ones with small widths. The structure constant values chosen do not seem to alter this situation. The kurtosis parameters of the beams having small widths are seen to be larger than the ones with the small widths. Again the choice of the structure constant does not change this trend.

Fast calculation method for computer-generated cylindrical holograms.

PubMed

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.

Microcrystalline diamond cylindrical resonators with quality-factor up to 0.5 million

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saito, Daisuke; Yang, Chen; Lin, Liwei

2016-02-01

We demonstrate high quality-factor 1.5 mm diameter batch-fabricated microcrystalline diamond cylindrical resonators (CR) with quality-factors limited by thermoelastic damping (TED) and surface loss. Resonators were fabricated 2.6 and 5.3 μm thick in-situ boron-doped microcrystalline diamond films deposited using hot filament chemical vapor deposition. The quality-factor (Q) of as-fabricated CR's was found to increase with the resonator diameter and diamond thickness. Annealing the CRs at 700 °C in a nitrogen atmosphere led to a three-fold increase in Q, a result we attribute to thinning of the diamond layer via reaction with residual O{sub 2} in the annealing furnace. Post-anneal Q exceeding 0.5 million (528 000)more » was measured at the 19 kHz elliptical wineglass modes, producing a ring-down time of 8.9 s. A model for Q versus diamond thickness and resonance frequency is developed including the effects of TED and surface loss. Measured quality factors are shown to agree with the predictions of this model.« less

Novel cylindrical illuminator tip for ultraviolet light delivery

NASA Astrophysics Data System (ADS)

Shangguan, HanQun; Haw, Thomas E.; Gregory, Kenton W.; Casperson, Lee W.

1993-06-01

The design, processing, and sequential testing of a novel cylindrical diffusing optical fiber tip for ultraviolet light delivery is described. This device has been shown to uniformly (+/- 15%) illuminate angioplasty balloons, 20 mm in length, that are used in an experimental photochemotherapeutic treatment of swine intimal hyperplasia. Our experiments show that uniform diffusing tips of < 400 micron diameter can be reliably constructed for this and other interstitial applications. Modeling results indicate that this design is scalable to smaller diameters. The diffusing tips are made by stripping the protective buffer and etching away the cladding over a length of 20 mm from the fiber tip and replacing it with a thin layer of optical epoxy mixed with Al2O3 powder. To improve the uniformity and ease of fabrication, we have evaluated a new device configuration where the tip is etched into a modified conical shape, and the distal end face is polished and then coated with an optically opaque epoxy. This is shown to uniformly scatter approximately 70% of the light launched into the fiber without forward transmission.

Correlation between mass transfer coefficient kLa and relevant operating parameters in cylindrical disposable shaken bioreactors on a bench-to-pilot scale

PubMed Central

2013-01-01

Background Among disposable bioreactor systems, cylindrical orbitally shaken bioreactors show important advantages. They provide a well-defined hydrodynamic flow combined with excellent mixing and oxygen transfer for mammalian and plant cell cultivations. Since there is no known universal correlation between the volumetric mass transfer coefficient for oxygen kLa and relevant operating parameters in such bioreactor systems, the aim of this current study is to experimentally determine a universal kLa correlation. Results A Respiration Activity Monitoring System (RAMOS) was used to measure kLa values in cylindrical disposable shaken bioreactors and Buckingham’s π-Theorem was applied to define a dimensionless equation for kLa. In this way, a scale- and volume-independent kLa correlation was developed and validated in bioreactors with volumes from 2 L to 200 L. The final correlation was used to calculate cultivation parameters at different scales to allow a sufficient oxygen supply of tobacco BY-2 cell suspension cultures. Conclusion The resulting equation can be universally applied to calculate the mass transfer coefficient for any of seven relevant cultivation parameters such as the reactor diameter, the shaking frequency, the filling volume, the viscosity, the oxygen diffusion coefficient, the gravitational acceleration or the shaking diameter within an accuracy range of +/− 30%. To our knowledge, this is the first kLa correlation that has been defined and validated for the cited bioreactor system on a bench-to-pilot scale. PMID:24289110

Modelling of heat transfer during torrefaction of large lignocellulosic biomass

NASA Astrophysics Data System (ADS)

Regmi, Bharat; Arku, Precious; Tasnim, Syeda Humaira; Mahmud, Shohel; Dutta, Animesh

2018-02-01

Preparation of feedstock is a major energy intensive process for the thermochemical conversion of biomass into fuel. By eliminating the need to grind biomass prior to the torrefaction process, there would be a potential gain in the energy requirements as the entire step would be eliminated. In regards to a commercialization of torrefaction technology, this study has examined heat transfer inside large cylindrical biomass both numerically and experimentally during torrefaction. A numerical axis-symmetrical 2-D model for heat transfer during torrefaction at 270°C for 1 h was created in COMSOL Multiphysics 5.1 considering heat generation evaluated from the experiment. The model analyzed the temperature distribution within the core and on the surface of biomass during torrefaction for various sizes. The model results showed similarities with experimental results. The effect of L/D ratio on temperature distribution within biomass was observed by varying length and diameter and compared with experiments in literature to find out an optimal range of cylindrical biomass size suitable for torrefaction. The research demonstrated that a cylindrical biomass sample of 50 mm length with L/D ratio of 2 can be torrefied with a core-surface temperature difference of less than 30 °C. The research also demonstrated that sample length has a negligible effect on core-surface temperature difference during torrefaction when the diameter is fixed at 25 mm. This information will help to design a torrefaction processing system and develop a value chain for biomass supply without using an energy-intensive grinding process.

Modelling of heat transfer during torrefaction of large lignocellulosic biomass

NASA Astrophysics Data System (ADS)

Regmi, Bharat; Arku, Precious; Tasnim, Syeda Humaira; Mahmud, Shohel; Dutta, Animesh

2018-07-01

Preparation of feedstock is a major energy intensive process for the thermochemical conversion of biomass into fuel. By eliminating the need to grind biomass prior to the torrefaction process, there would be a potential gain in the energy requirements as the entire step would be eliminated. In regards to a commercialization of torrefaction technology, this study has examined heat transfer inside large cylindrical biomass both numerically and experimentally during torrefaction. A numerical axis-symmetrical 2-D model for heat transfer during torrefaction at 270°C for 1 h was created in COMSOL Multiphysics 5.1 considering heat generation evaluated from the experiment. The model analyzed the temperature distribution within the core and on the surface of biomass during torrefaction for various sizes. The model results showed similarities with experimental results. The effect of L/D ratio on temperature distribution within biomass was observed by varying length and diameter and compared with experiments in literature to find out an optimal range of cylindrical biomass size suitable for torrefaction. The research demonstrated that a cylindrical biomass sample of 50 mm length with L/D ratio of 2 can be torrefied with a core-surface temperature difference of less than 30 °C. The research also demonstrated that sample length has a negligible effect on core-surface temperature difference during torrefaction when the diameter is fixed at 25 mm. This information will help to design a torrefaction processing system and develop a value chain for biomass supply without using an energy-intensive grinding process.

Correlation between mass transfer coefficient kLa and relevant operating parameters in cylindrical disposable shaken bioreactors on a bench-to-pilot scale.

PubMed

Klöckner, Wolf; Gacem, Riad; Anderlei, Tibor; Raven, Nicole; Schillberg, Stefan; Lattermann, Clemens; Büchs, Jochen

2013-12-02

Among disposable bioreactor systems, cylindrical orbitally shaken bioreactors show important advantages. They provide a well-defined hydrodynamic flow combined with excellent mixing and oxygen transfer for mammalian and plant cell cultivations. Since there is no known universal correlation between the volumetric mass transfer coefficient for oxygen kLa and relevant operating parameters in such bioreactor systems, the aim of this current study is to experimentally determine a universal kLa correlation. A Respiration Activity Monitoring System (RAMOS) was used to measure kLa values in cylindrical disposable shaken bioreactors and Buckingham's π-Theorem was applied to define a dimensionless equation for kLa. In this way, a scale- and volume-independent kLa correlation was developed and validated in bioreactors with volumes from 2 L to 200 L. The final correlation was used to calculate cultivation parameters at different scales to allow a sufficient oxygen supply of tobacco BY-2 cell suspension cultures. The resulting equation can be universally applied to calculate the mass transfer coefficient for any of seven relevant cultivation parameters such as the reactor diameter, the shaking frequency, the filling volume, the viscosity, the oxygen diffusion coefficient, the gravitational acceleration or the shaking diameter within an accuracy range of +/- 30%. To our knowledge, this is the first kLa correlation that has been defined and validated for the cited bioreactor system on a bench-to-pilot scale.

Paramagnetic Liquid Bridge in a Gravity-Compensating Magnetic Field

NASA Technical Reports Server (NTRS)

Mahajan, Milind P.; Tsige, Mesfin; Taylor, P. L.; Rosenblatt, Charles

1999-01-01

Magnetic levitation was used to stabilize cylindrical columns of a paramagnetic liquid in air between two solid supports. The maximum achievable length to diameter ratio R(sub max) was approx. (3.10 +/- 0.07), very close to the Rayleigh-Plateau limit of pi. For smaller R, the stability of the column was measured as a function of the Bond number, which could be continuously varied by adjusting the strength of the magnetic field. Liquid bridges supported by two solid surfaces have been attracting scientific attention since the time of Rayleigh and Plateau. For a cylindrical bridge of length L and diameter d, it was shown theoretically that in zero gravity the maximum slenderness ratio R (identically = L/d) is pi. The stability and ultimate collapse of such bridges is of interest because of their importance in a number of industrial processes and their potential for low gravity applications. In the presence of gravity, however, the cylindrical shape of an axisymmetric bridge tends to deform, limiting its stability and decreasing the maximum achievable value of R. Theoretical studies have discussed the stability and possible shapes of axisymmetric bridges. Experiments typically are performed in either a Plateau tank, in which the bridge is surrounded by a density-matched immiscible fluid, or in a space-borne microgravity environment. It has been shown, for example, that the stability limit R can be pushed beyond pi by using flow stabilization, by acoustic radiation pressure, or by forming columns in the presence of an axial electric field. In this work, magnetic levitation was used to simulate a low gravity environment and create quasi-cylindrical liquid columns in air. Use of a magnetic field permits us to continuously vary the Bond number B identically equal to (g)(rho)d(exp 2)/4(sigma), where g is the gravitational acceleration, rho is the density of the liquid, and sigma is the surface tension of the liquid in air. The dimensionless Bond number represents the relative importance of external forces acting on the liquid column to those due to surface tension. Our central result is that in a large magnetic field gradient we could create and stabilize columns of mixtures of water and paramagnetic manganese chloride tetrahydrate (MnCl2.4H2O), achieving a length to diameter ratio very close to pi.

Theoretical analysis of swelling characteristics of cylindrical uranium dioxide fuel pins with a niobium - 1-percent-zirconium clad

NASA Technical Reports Server (NTRS)

Saltsman, J. F.

1973-01-01

The relations between clad creep strain and fuel volume swelling are shown for cylindrical UO2 fuel pins with a Nb-1Zr clad. These relations were obtained by using the computer code CYGRO-2. These clad-strain - fuel-volume-swelling relations may be used with any fuel-volume-swelling model, provided the fuel volume swelling is isotropic and independent of the clad restraints. The effects of clad temperature (over a range from 118 to 1642 K (2010 to 2960 R)), pin diameter, clad thickness and central hole size in the fuel have been investigated. In all calculations the irradiation time was 500 hours. The burnup rate was varied.

Reactor design for uniform chemical vapor deposition-grown films without substrate rotation

DOEpatents

Wanlass, M.

1985-02-19

A quartz reactor vessel for growth of uniform semiconductor films includes a vertical, cylindrical reaction chamber in which a substrate-supporting pedestal provides a horizontal substrate-supporting surface spaced on its perimeter from the chamber wall. A cylindrical confinement chamber of smaller diameter is disposed coaxially above the reaction chamber and receives reaction gas injected at a tangent to the inside chamber wall, forming a helical gas stream that descends into the reaction chamber. In the reaction chamber, the edge of the substrate-supporting pedestal is a separation point for the helical flow, diverting part of the flow over the horizontal surface of the substrate in an inwardly spiraling vortex.

Reactor design for uniform chemical vapor deposition-grown films without substrate rotation

DOEpatents

Wanlass, Mark

1987-01-01

A quartz reactor vessel for growth of uniform semiconductor films includes a vertical, cylindrical reaction chamber in which a substrate-supporting pedestal provides a horizontal substrate-supporting surface spaced on its perimeter from the chamber wall. A cylindrical confinement chamber of smaller diameter is disposed coaxially above the reaction chamber and receives reaction gas injected at a tangent to the inside chamber wall, forming a helical gas stream that descends into the reaction chamber. In the reaction chamber, the edge of the substrate-supporting pedestal is a separation point for the helical flow, diverting part of the flow over the horizontal surface of the substrate in an inwardly spiraling vortex.

Function of membrane protein in silica nanopores: incorporation of photosynthetic light-harvesting protein LH2 into FSM.

PubMed

Oda, Ippei; Hirata, Kotaro; Watanabe, Syoko; Shibata, Yutaka; Kajino, Tsutomu; Fukushima, Yoshiaki; Iwai, Satoshi; Itoh, Shigeru

2006-01-26

A high amount of functional membrane protein complex was introduced into a folded-sheet silica mesoporous material (FSM) that has nanometer-size pores of honeycomb-like hexagonal cylindrical structure inside. The photosynthetic light-harvesting complex LH2, which is a typical membrane protein, has a cylindrical structure of 7.3 nm diameter and contains 27 bacteriochlorophyll a and nine carotenoid molecules. The complex captures light energy in the anoxygenic thermophilic purple photosynthetic bacterium Thermochromatium tepidum. The amount of LH2 adsorbed to FSM was determined optically and by the adsorption isotherms of N2. The FSM compounds with internal pore diameters of 7.9 and 2.7 nm adsorbed LH2 at 1.11 and 0.24 mg/mg FSM, respectively, suggesting the high specific affinity of LH2 to the interior of the hydrophobic nanopores with a diameter of 7.9 nm. The LH2 adsorbed to FSM showed almost intact absorption bands of bacteriochlorophylls, and was fully active in the capture and transfer of excitation energy. The LH2 complex inside the FSM showed increased heat stability of the exciton-type absorption band of bacteriochlorophylls (B850), suggesting higher circular symmetry. The environment inside the hydrophobic silica nanopores can be a new matrix for the membrane proteins to reveal their functions. The silica-membrane protein adduct will be useful for the construction of new probes and reaction systems.

Automated Figuring and Polishing of Replication Mandrels for X-Ray Telescopes

NASA Technical Reports Server (NTRS)

Krebs, Carolyn (Technical Monitor); Content, David; Fleetwood, Charles; Wright, Geraldine; Arsenovic, Petar; Collela, David; Kolos, Linette

2003-01-01

In support of the Constellation X mission the Optics Branch at Goddard Space Flight Center is developing technology for precision figuring and polishing of mandrels used to produce replicated mirrors that will be used in X-Ray telescopes. Employing a specially built machine controlled in 2 axes by a computer, we are doing automated polishing/figuring of 15 cm long, 20 cm diameter cylindrical, conical and Wolter mandrels. A battery of tests allow us to fully characterize all important aspects of the mandrels, including surface figure and finish, mid-frequency errors, diameters and cone angle. Parts are currently being produced with surface roughnesses at the .5nm RMS level, and half-power diameter slope error less than 2 arcseconds.

Minimizing Concentration Effects in Water-Based, Laminar-Flow Condensation Particle Counters

PubMed Central

Lewis, Gregory S.; Hering, Susanne V.

2013-01-01

Concentration effects in water condensation systems, such as used in the water-based condensation particle counter, are explored through numeric modeling and direct measurements. Modeling shows that the condensation heat release and vapor depletion associated with particle activation and growth lowers the peak supersaturation. At higher number concentrations, the diameter of the droplets formed is smaller, and the threshold particle size for activation is higher. This occurs in both cylindrical and parallel plate geometries. For water-based systems we find that condensational heat release is more important than is vapor depletion. We also find that concentration effects can be minimized through use of smaller tube diameters, or more closely spaced parallel plates. Experimental measurements of droplet diameter confirm modeling results. PMID:24436507

A Study of Cavitation Erosion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hiromu Isaka; Masatsugu Tsutsumi; Tadashi Shiraishi

2002-07-01

The authors performed experimental study for the purpose of the following two items from a viewpoint of cavitation erosion of a cylindrical orifice in view of a problem at the letdown orifice in PWR (Pressurized Water Reactor). 1. To get the critical cavitation parameter of the cylindrical orifice to establish the design criteria for prevention of cavitation erosion, and 2. to ascertain the erosion rate in such an eventuality that the cavitation erosion occurs with the orifice made of stainless steel with precipitation hardening (17-4-Cu hardening type stainless steel), so that we confirm the appropriateness of the design criteria. Regardingmore » the 1. item, we carried out the cavitation tests to get the critical cavitation parameters inside and downstream of the orifice. The test results showed that the cavitation parameter at inception is independent of the length or the diameter of the orifice. Moreover, the design criteria of cavitation erosion of cylindrical orifices have been established. Regarding the 2. item, we tested the erosion rate under high-pressure conditions. The cavitation erosion actually occurred in the cylindrical orifice at the tests that was strongly resemble to the erosion occurred at the plant. It will be seldom to reproduce resemble cavitation erosion in a cylindrical orifice with the hard material used at plants. We could establish the criteria for preventing the cavitation erosion from the test results. (authors)« less

Self-folding polymeric containers for encapsulation and delivery of drugs.

PubMed

Fernandes, Rohan; Gracias, David H

2012-11-01

Self-folding broadly refers to self-assembly processes wherein thin films or interconnected planar templates curve, roll-up or fold into three dimensional (3D) structures such as cylindrical tubes, spirals, corrugated sheets or polyhedra. The process has been demonstrated with metallic, semiconducting and polymeric films and has been used to curve tubes with diameters as small as 2nm and fold polyhedra as small as 100nm, with a surface patterning resolution of 15nm. Self-folding methods are important for drug delivery applications since they provide a means to realize 3D, biocompatible, all-polymeric containers with well-tailored composition, size, shape, wall thickness, porosity, surface patterns and chemistry. Self-folding is also a highly parallel process, and it is possible to encapsulate or self-load therapeutic cargo during assembly. A variety of therapeutic cargos such as small molecules, peptides, proteins, bacteria, fungi and mammalian cells have been encapsulated in self-folded polymeric containers. In this review, we focus on self-folding of all-polymeric containers. We discuss the mechanistic aspects of self-folding of polymeric containers driven by differential stresses or surface tension forces, the applications of self-folding polymers in drug delivery and we outline future challenges. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of experimental and theoretical normal-force distributions (including Reynolds number effects) on an ogive-cylinder body at Mach number 1.98

NASA Technical Reports Server (NTRS)

Perkins, Edward W; Jorgensen, Leland H

1956-01-01

Effects of Reynolds number and angle of attack on the pressure distribution and normal-force characteristics of a body of revolution consisting of a fineness ratio 3 ogival nose tangent to a cylindrical afterbody 7 diameters long have been determined. The test Mach number was 1.98 and the angle-of-attack range from 0 degree to 20 degrees. The Reynolds numbers, based on body diameter, were 0.15 x 10(6) and 0.45 x 10(6). The experimental results are compared with theory.

Large-aperture interferometer using local reference beam

NASA Technical Reports Server (NTRS)

Howes, W. L.

1982-01-01

A large-aperture interferometer was devised by adding a local-reference-beam-generating optical system to a schlieren system. Two versions of the interferometer are demonstrated, one employing 12.7 cm (5 in.) diameter schlieren optics, the other employing 30.48 cm (12 in.) diameter parabolic mirrors in an off-axis system. In the latter configuration a cylindrical lens is introduced near the light source to correct for astigmatism. A zone plate is a satisfactory decollimating element in the reference-beam arm of the interferometer. Attempts to increase the flux and uniformity of irradiance in the reference beam by using a diffuser are discussed.

Investigation of Some Wake Vortex Characteristics of an Inclined Ogive-Cylinder Body at Mach Number 2

NASA Technical Reports Server (NTRS)

Jorgensen, Leland H; Perkins, Edward W

1958-01-01

For a body consisting of a fineness-ratio-3 ogival nose tangent to a cylindrical afterbody 7.3 diameters long, pitot-pressure distributions in the flow field, pressure distributions over the body, and downwash distributions along a line through the vortex centers have been measured for angles of attack to 20 degrees. The Reynolds numbers, based on body diameter, were 0.15 x 10 to the 6th power and 0.44 x 10 to the 6th power. Comparisons of computed and measured vortex paths and downwash distributions are made. (author)

A high-performance magnetic shield with large length-to-diameter ratio.

PubMed

Dickerson, Susannah; Hogan, Jason M; Johnson, David M S; Kovachy, Tim; Sugarbaker, Alex; Chiow, Sheng-wey; Kasevich, Mark A

2012-06-01

We have demonstrated a 100-fold improvement in the magnetic field uniformity on the axis of a large aspect ratio, cylindrical, mumetal magnetic shield by reducing discontinuities in the material of the shield through the welding and re-annealing of a segmented shield. The three-layer shield reduces Earth's magnetic field along an 8 m region to 420 μG (rms) in the axial direction, and 460 and 730 μG (rms) in the two transverse directions. Each cylindrical shield is a continuous welded tube which has been annealed after manufacture and degaussed in the apparatus. We present both experiments and finite element analysis that show the importance of uniform shield material for large aspect ratio shields, favoring a welded design over a segmented design. In addition, we present finite element results demonstrating the smoothing of spatial variations in the applied magnetic field by cylindrical magnetic shields. Such homogenization is a potentially useful feature for precision atom interferometric measurements.

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.

Prosthetic helping hand

NASA Technical Reports Server (NTRS)

Vest, Thomas W. (Inventor); Carden, James R. (Inventor); Norton, William E. (Inventor); Belcher, Jewell G. (Inventor)

1992-01-01

A prosthetic device for below-the-elbow amputees, having a C-shaped clamping mechanism for grasping cylindrical objects, is described. The clamping mechanism is pivotally mounted to a cuff that fits on the amputee's lower arm. The present invention is utilized by placing an arm that has been amputated below the elbow into the cuff. The clamping mechanism then serves as a hand whenever it becomes necessary for the amputee to grasp a cylindrical object such as a handle, a bar, a rod, etc. To grasp the cylindrical object, the object is jammed against the opening in the C-shaped spring, causing the spring to open, the object to pass to the center of the spring, and the spring to snap shut behind the object. Various sizes of clamping mechanisms can be provided and easily interchanged to accommodate a variety of diameters. With the extension that pivots and rotates, the clamping mechanism can be used in a variety of orientations. Thus, this invention provides the amputee with a clamping mechanism that can be used to perform a number of tasks.

Electron Bernstein Wave Studies in MST

NASA Astrophysics Data System (ADS)

Seltzman, Andrew; Anderson, Jay; Forest, Cary; Nonn, Paul; Thomas, Mark; Almagri, Abdulgader; Chapman, Brett; Dubois, Ami; Goetz, John; McCollam, Karsten

2015-11-01

The RFP plasma is inaccessible to ECRH, requiring the electron Bernstein wave (EBW) for edge localized heating and current drive. MST is capable of generating RFPs or overdense tokamaks with Bt(0) ~ 0.08-0.14T in which a 5.55 GHz RF source (450kW, 2ms pulse) can heat at fundamental and harmonic EC resonances. The design of a suitable antenna is challenging in the RFP due to a magnetic field geometry that requires a low-field-side launch. The small vacuum gap between the close-fitting conducting shell and plasma leads to substantial antenna-plasma interaction. A minimized port hole size is required to limit error fields. Even so the port hole induced magnetic field perturbation in the antenna near-field that affects the mode conversion process and introduces EC resonances. A 5cm diameter cylindrical antenna centered in 5cm and 11cm diameter portholes is used. A multi-chord time-resolved x-ray detector and GENRAY ray tracing verifies EBW heating at higher harmonics in an MST tokamak with 10-40keV detected x-ray energies. Evidence of RF-induced emission from absorption at higher harmonics (4th / 5th) in low current RFP discharges has been observed. Simultaneous reflected power changes correspond to termination of x-ray emission indicating power limits. Work supported by USDOE.

Method of making monodisperse nanoparticles

DOEpatents

Fan, Hongyon; Sun, Zaicheng

2012-10-16

A method of making particles of either spherical or cylindrical geometry with a characteristic diameter less than 50 nanometers by mixing at least one structure directing agent dissolved in a solvent with at least one amphiphilic block copolymer dissolved in a solvent to make a solution containing particles, where the particles can be subsequently separated and dispersed in a solvent of choice.

Novel fuelbed characteristics associated with mechanical mastication treatments in northern California and south-western Oregon, USA

Treesearch

Jeffrey M. Kane; J. Morgan Varner; Eric E. Knapp

2009-01-01

Mechanically masticated fuelbeds are distinct from natural or logging slash fuelbeds, with different particle size distributions, bulk density, and particle shapes, leading to challenges in predicting fire behavior and effects. Our study quantified some physical properties of fuel particles (e.g. squared quadratic mean diameter, proportion of non-cylindrical particles...

30 CFR 18.66 - Tests of windows and lenses.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Tests of windows and lenses. 18.66 Section 18... Tests § 18.66 Tests of windows and lenses. (a) Impact tests. A 4-pound cylindrical weight with a 1-inch-diameter hemispherical striking surface shall be dropped (free fall) to strike the window or lens in its...

Design and dosimetry of small animal radiation facilities

NASA Astrophysics Data System (ADS)

Rodriguez, Manuel R.

The aim of this work was to develop an irradiation system for radiobiology studies. We designed a novel image-guided micro-irradiator capable of partial-body zebrafish embryo irradiation. The radiation source is a 50 kV photon beam from a miniature x-ray source (Xoft Inc., CA). The source is inserted in a cylindrical brass collimator, 3 cm in diameter and 3 cm in length. The collimator has a 1 mm-diameter pinhole along the longitudinal axis, which provides a well-focused beam with a sharp penumbra. A photodiode is installed at one exit of the pinhole collimator to monitor the photon dose rate. The source with the collimator is attached under a movable table. A video camera, connected to the computer, is placed above the movable table to record position of the specimens in relation to the pinhole collimator. The captured images are analyzed, and the relative distances between the specimens and the pinhole are calculated. The coordinates are sent to the computer-controlled movable table to accurately position the specimens in the beam. Monte Carlo simulations were performed to characterize dosimetric properties of the system, to determine dosimetric sensitivity, and to help in the design. The image-guidance and high precision of the movable table enable very accurate specimen position. The beam monitoring system provides accurate, fast and easy dose determination. Portability and self-shielding make this system suitable for any radiobiology laboratory. This novel micro-irradiator is appropriate for partial irradiation of zebrafish embryos; however its potential use is much wider like irradiation of cell cultures or other small specimens.

Distributed force probe bending model of critical dimension atomic force microscopy bias

NASA Astrophysics Data System (ADS)

Ukraintsev, Vladimir A.; Orji, Ndubuisi G.; Vorburger, Theodore V.; Dixson, Ronald G.; Fu, Joseph; Silver, Rick M.

2013-04-01

Critical dimension atomic force microscopy (CD-AFM) is a widely used reference metrology technique. To characterize modern semiconductor devices, small and flexible probes, often 15 to 20 nm in diameter, are used. Recent studies have reported uncontrolled and significant probe-to-probe bias variation during linewidth and sidewall angle measurements. To understand the source of these variations, tip-sample interactions between high aspect ratio features and small flexible probes, and their influence on measurement bias, should be carefully studied. Using theoretical and experimental procedures, one-dimensional (1-D) and two-dimensional (2-D) models of cylindrical probe bending relevant to carbon nanotube (CNT) AFM probes were developed and tested. An earlier 1-D bending model was refined, and a new 2-D distributed force (DF) model was developed. Contributions from several factors were considered, including: probe misalignment, CNT tip apex diameter variation, probe bending before snapping, and distributed van der Waals-London force. A method for extracting Hamaker probe-surface interaction energy from experimental probe-bending data was developed. Comparison of the new 2-D model with 1-D single point force (SPF) model revealed a difference of about 28% in probe bending. A simple linear relation between biases predicted by the 1-D SPF and 2-D DF models was found. The results suggest that probe bending can be on the order of several nanometers and can partially explain the observed CD-AFM probe-to-probe variation. New 2-D and three-dimensional CD-AFM data analysis software is needed to take full advantage of the new bias correction modeling capabilities.

Low-frequency vibrations of a cylindrical shell rotating on rollers

NASA Astrophysics Data System (ADS)

Filippov, S. B.

2018-05-01

Small free low-frequency vibrations of a rotating closed cylindrical shell which is in a contact with rigid cylindrical rollers are considered. Assumptions of semi-momentless shell theory are used. By means of the expansion of solutions in truncated Fourier series in circumference coordinate the system of the algebraic equations for the approximate calculation of the vibration frequencies and the mode shapes is obtained. The algorithm for the evaluation of frequencies and vibration modes based on analytical solution is developed. In particular, the lowest frequencies of thin cylindrical shell, representing greatest interest for applications, were found. Approximate results are compared with results of numerical calculations carried out by the Finite Elements Analysis. It is shown that the semi-momentless theory can be used for the evaluation of the low frequencies of a cylindrical shell rotating on rollers.

Nuclear reactor heat transport system component low friction support system

DOEpatents

Wade, Elman E.

1980-01-01

A support column for a heavy component of a liquid metal fast breeder reactor heat transport system which will deflect when the pipes leading coolant to and from the heavy component expand or contract due to temperature changes includes a vertically disposed pipe, the pipe being connected to the heavy component by two longitudinally spaced cycloidal dovetail joints wherein the distal end of each of the dovetails constitutes a part of the surface of a large diameter cylinder and the centerlines of these large diameter cylinders intersect at right angles and the pipe being supported through two longitudinally spaced cycloidal dovetail joints wherein the distal end of each of the dovetails constitutes a part of the surface of a large diameter cylinder and the centerlines of these large diameter cylinders intersect at right angles, each of the cylindrical surfaces bearing on a flat and horizontal surface.

Fluid-structure interaction of a rolling restrained body of revolution at high angles of attack

NASA Astrophysics Data System (ADS)

Degani, D.; Ishay, M.; Gottlieb, O.

2017-03-01

The current work investigates numerically rolling instabilities of a free-to-roll slender rigid-body of revolution placed in a wind tunnel at a high angle of attack. The resistance to the roll moment is represented by a linear torsion spring and equivalent linear damping representing friction in the bearings of a simulated wind tunnel model. The body is subjected to a three-dimensional, compressible, laminar flow. The full Navier-Stokes equations are solved using the second-order implicit finite difference Beam-Warming scheme, adapted to a curvilinear coordinate system, whereas the coupled structural second order equation of motion for roll is solved by a fourth-order Runge-Kutta method. The body consists of a 3.5-diameter tangent ogive forebody with a 7.0-diameter long cylindrical afterbody extending aft of the nose-body junction to x/D = 10.5. We describe in detail the investigation of three angles of attack 20°, 40°, and 65°, at a Reynolds number of 30 000 (based on body diameter) and a Mach number of 0.2. Three distinct configurations are investigated as follows: a fixed body, a free-to-roll body with a weak torsion spring, and a free-to-roll body with a strong torsion spring. For each angle of attack the free-to-roll configuration portrays a distinct and different behavior pattern, including bi-stable limit-cycle oscillations. The bifurcation structure incorporates both large and small amplitude periodic roll oscillations where the latter lose their periodicity with increasing stiffness of the restraining spring culminating with distinct quasiperiodic oscillations. We note that removal of an applied upstream disturbance for a restrained body does not change the magnitude or complexity of the oscillations or of the flow patterns along the body. Depending on structure characteristics and flow conditions even a small rolling moment coefficient at the relatively low angle of attack of 20° may lead to large amplitude resonant roll oscillations.

Open-Ended Coaxial Dielectric Probe Effective Penetration Depth Determination.

PubMed

Meaney, Paul M; Gregory, Andrew P; Seppälä, Jan; Lahtinen, Tapani

2016-03-01

We have performed a series of experiments which demonstrate the effect of open-ended coaxial diameter on the depth of penetration. We used a two layer configuration of a liquid and movable cylindrical piece of either Teflon or acrylic. The technique accurately demonstrates the depth in a sample for which a given probe diameter provides a reasonable measure of the bulk dielectric properties for a heterogeneous volume. In addition we have developed a technique for determining the effective depth for a given probe diameter size. Using a set of simulations mimicking four 50 Ω coaxial cable diameters, we demonstrate that the penetration depth in both water and saline has a clear dependence on probe diameter but is remarkably uniform over frequency and with respect to the intervening liquid permittivity. Two different 50 Ω commercial probes were similarly tested and confirm these observations. This result has significant implications to a range of dielectric measurements, most notably in the area of tissue property studies.

Open-Ended Coaxial Dielectric Probe Effective Penetration Depth Determination

PubMed Central

Meaney, Paul M.; Gregory, Andrew P.; Seppälä, Jan; Lahtinen, Tapani

2016-01-01

We have performed a series of experiments which demonstrate the effect of open-ended coaxial diameter on the depth of penetration. We used a two layer configuration of a liquid and movable cylindrical piece of either Teflon or acrylic. The technique accurately demonstrates the depth in a sample for which a given probe diameter provides a reasonable measure of the bulk dielectric properties for a heterogeneous volume. In addition we have developed a technique for determining the effective depth for a given probe diameter size. Using a set of simulations mimicking four 50 Ω coaxial cable diameters, we demonstrate that the penetration depth in both water and saline has a clear dependence on probe diameter but is remarkably uniform over frequency and with respect to the intervening liquid permittivity. Two different 50 Ω commercial probes were similarly tested and confirm these observations. This result has significant implications to a range of dielectric measurements, most notably in the area of tissue property studies. PMID:27346890

An experimental investigation of the effect of walls on gas-liquid flows through fixed particle beds.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, Marcia A.; Cote, Raymond O.; Torczynski, John Robert

The effect of particle diameter on downward co-current gas-liquid flow through a fixed bed of particles confined within a cylindrical column is investigated. Several hydrodynamic regimes that depend strongly on the properties of the gas stream, the liquid stream, and the packed particle bed are known to exist within these systems. This experimental study focuses on characterizing the effect of wall confinement on these hydrodynamic regimes as the diameter d of the spherical particles becomes comparable to the column diameter D (or D/d becomes order-unity). The packed bed consists of polished, solid, spherical, monodisperse particles (beads) with mean diameter inmore » the range of 0.64-2.54 cm. These diameters yield D/d values between 15 and 3.75, so this range overlaps and extends the previously investigated range for two-phase flow, Measurements of the pressure drop across the bed and across the pulses are obtained for varying gas and liquid flow rates.« less

Performance Evaluation and Initial Clinical Test of the Positron Emission Mammography System (PEMi)

NASA Astrophysics Data System (ADS)

Li, Lin; Gu, Xiao-Yue; Li, Dao-Wu; Huang, Xian-Chao; Chai, Pei; Feng, Bao-Tong; Wang, Pei-Lin; Yun, Ming-Kai; Dai, Dong; Zhang, Zhi-Ming; Yin, Peng-Fei; Xu, Wen-Gui; Wei, Long

2015-10-01

A new polygon positron emission mammography imaging system (PEMi) was developed in 2009 by the Institute of High Energy Physics, Chinese Academy of Sciences. PEMi is constructed in a polygon structure with lutetium yttrium orthosilicate crystal arrays mounted on a position-sensitive photomultiplier. The system consists of 64 blocks and each block is arranged in 16 ×16 crystal arrays with a pixel size of 1.9 ×1.9 ×15 mm. The diameter of the detector ring is 166 mm, and the axial length is 128 mm. The transaxial field of view of PEMi is 110 mm. The goal of the initial study was to test PEMi's performance and the clinical imaging ability with a small group of selected subjects. The detectors have a measured intrinsic spatial resolution averaging 1.67 mm. The axial and tangential resolution remained under 2.5-mm full width at half maximum within the central 5-cm diameter of the field of view. The hot rods with a diameter of 1.7 mm can be clearly identified, and the structure of the region containing 1.35-mm diameter rods can also be observed. Using a 6-ns coincidence timing window and a 360 660-keV energy window, the peak sensitivity of the tomograph is 6.88%. The noise-equivalent count rate peak is 110 766 cps for a breast-like cylindrical phantom of 100 mm in diameter at an activity concentration of 0.03 MBq/cc. The recovery coefficients ranged from 0.21 to 0.85 for rods between 1 mm and 5 mm in the image-quality phantom. The reconstructed image resolution achieved an improvement compared with whole-body positron emission tomography (PET), which might reduce the lower threshold on detectable lesion size. Example patient images demonstrate that PEMi is clinically feasible. And more detailed structure information was obtained with PEMi than with the whole-body PET imaging.

Electrical contact tool set station

DOEpatents

Byers, M.E.

1988-02-22

An apparatus is provided for the precise setting to zero of electrically conductive cutting tools used in the machining of work pieces. An electrically conductive cylindrical pin, tapered at one end to a small flat, rests in a vee-shaped channel in a base so that its longitudinal axis is parallel to the longitudinal axis of the machine's spindle. Electronic apparatus is connected between the cylindrical pin and the electrically conductive cutting tool to produce a detectable signal when contact between tool and pin is made. The axes of the machine are set to zero by contact between the cutting tool and the sides, end or top of the cylindrical pin. Upon contact, an electrical circuit is completed, and the detectable signal is produced. The tool can then be set to zero for that axis. Should the tool contact the cylindrical pin with too much force, the cylindrical pin would be harmlessly dislodged from the vee-shaped channel, preventing damage either to the cutting tool or the cylindrical pin. 5 figs.

Alfven waves associated with long cylindrical satellites

NASA Technical Reports Server (NTRS)

Venkataraman, N. S.; Gustafson, W. A.

1973-01-01

The Alfven wave excited by a long cylindrical satellite moving with a constant velocity at an angle relative to a uniform magnetic field has been calculated. Assuming a plasma with infinite conductivity, the linearized momentum equation and Maxwell's equations are applied to a cylindrical satellite carrying a variable current. The induced magnetic field is determined, and it is shown that the Alfven disturbance zone is of limited extent, depending on the satellite shape. The wave drag coefficient is calculated and shown to be small compared to the induction drag coefficient at all altitudes considered.

Size-dependent scanning parameters (kVp and mAs) for photon-counting spectral CT system in pediatric imaging: simulation study

NASA Astrophysics Data System (ADS)

Chen, Han; Danielsson, Mats; Xu, Cheng

2016-06-01

We are developing a photon-counting spectral CT detector with a small pixel size of 0.4× 0.5 mm2, offering a potential advantage for better visualization of small structures in pediatric patients. The purpose of this study is to determine the patient size dependent scanning parameters (kVp and mAs) for pediatric CT in two imaging cases: adipose imaging and iodinated blood imaging. Cylindrical soft-tissue phantoms of diameters between 10-25 cm were used to mimic patients of different ages from 0 to 15 y. For adipose imaging, a 5 mm diameter adipose sphere was assumed as an imaging target, while in the case of iodinated imaging, an iodinated blood sphere of 1 mm in diameter was assumed. By applying the geometry of a commercial CT scanner (GE Lightspeed VCT), simulations were carried out to calculate the detectability index, {{d}\\prime 2} , with tube potentials varying from 40 to 140 kVp. The optimal kVp for each phantom in each imaging case was determined such that the dose-normalized detectability index, {{d}\\prime 2}/ dose, is maximized. With the assumption that the detectability index in pediatric imaging is required the same as in typical adult imaging, the value of mAs at optimal kVp for each phantom was selected to achieve a reference detectability index that was obtained by scanning an adult phantom (30 cm in diameter) in a typical adult CT procedure (120 kVp and 200 mAs) using a modeled energy-integrating system. For adipose imaging, the optimal kVps are 50, 60, 80, and 120 kVp, respectively, for phantoms of 10, 15, 20, and 25 cm in diameter. The corresponding mAs values required to achieve the reference detectability index are only 9%, 23%, 24%, and 54% of the mAs that is used for adult patients at 120 kVp, for 10, 15, 20, and 25 cm diameter phantoms, respectively. In the case of iodinated imaging, a tube potential of 60 kVp was found optimal for all phantoms investigated, and the mAs values required to achieve the reference detectability index are 2%, 9%, 37%, and 109% of the adult mAs. The results also indicate that with the use of respective optimal kVps, the photon-counting spectral system offers up to 30% higher {{d}\\prime 2}/ dose than the modeled energy-integrating system for adipose imaging, and 70% for iodinated imaging.

Modeling light scattering in the shadow region behind thin cylinders for diameter analysis

NASA Astrophysics Data System (ADS)

Blohm, Werner

2018-03-01

In this paper, the scattered light intensities resulting in the shadow region at an observation plane behind monochromatically illuminated circular cylinders are modeled by sinusoidal sequences having a squared dependence on spatial position in the observation plane. Whereas two sinusoidal components appear to be sufficient for modeling the light distribution behind intransparent cylinders, at least three sinusoidal components are necessary for transparent cylinders. Based on this model, a novel evaluation algorithm for a very fast retrieval of the diameter of thin cylindrical products like metallic wires and transparent fibers is presented. This algorithm was tested in a cylinder diameter range typical for these products (d ≈ 70 … 150 μm; n ≈ 1.5). Numerical examples are given to illustrate its application by using both synthetic and experimental scattering data. Diameter accuracies below 0.05 μm could be achieved for intransparent cylinders in the tested diameter range. However, scattering effects due to morphological-dependent resonances (MDRs) are problematical in the diameter analysis of transparent products. In order to incorporate these effects into the model, further investigations are needed.

[Accuracy of Modulation Transfer Function for Target Size and Field of View in a Circular Edge Strategy Using the CT Image Measurement Program].

PubMed

Fukunaga, Masaaki; Onishi, Hideo; Matsutomo, Norikazu; Yamamoto, Hiroyuki

2016-06-01

The purpose of this study was to evaluate the effects of target diameter and display-field of view (D-FOV) in modulation transfer function (MTF) by circular edge strategy using the computed tomography (CT) image measurement program "CTmeasure". We calculated the MTF (MTF(edge)) using the circular edge strategy applied to cylindrical phantom (200 mmφ) that inserted with cylinders have 10, 20, 30, and 40 mm diameters. The phantom images were reconstructed using filtered back projection method varied with D-FOV (240, 320, 400, and 500 mm). The study compared both MTF(edge) and MTF(wire) at MTF50% and MTF(10%) for target diameter and D-FOV, respectively. The MTF(edge) by the different of target diameter indicated in rough compatibility. However, MTF(edge) of D-FOV diameters (320, 400, and 500 mm) decreased in the high frequency range. The circular edge strategy for MTF depended on the D-FOV, however, it was little dependent on target diameter using the CT image measurement program "CTmeasure".

Implosion dynamics of a megampere wire-array Z-pinch with an inner low-density foam shell at the Angara-5-1 facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aleksandrov, V. V.; Bolkhovitinov, E. A.; Volkov, G. S., E-mail: volkov@triniti.ru

The implosion dynamics of a pinch with a highly inhomogeneous initial axial distribution of the load mass was studied experimentally. A cascade array consisting of a double nested tungsten wire array and a coaxial inner cylindrical shell located symmetrically with respect to the high-voltage electrodes was used as a load of the Angara-5-1 high-current generator. The cylindrical foam shell was half as long as the cathode− anode gap, and its diameter was equal to the diameter of the inner wire array. It is shown experimentally that two stages are typical of the implosion dynamics of such a load: the formationmore » of two separate pinches formed as a result of implosion of the wire array near the cathode and anode and the subsequent implosion of the central part of the load containing the cylindrical foam shell. The conditions are determined at which the implosion of the central part of the pinch with the foam cylinder is preceded by intense irradiation of the foam with the soft X-ray (SXR) emission generated by the near-electrode pinches and converting it into the plasma state. Using such a load, which models the main elements of the scheme of a dynamic hohlraum for inertial confinement fusion, it is possible to increase the efficiency of interaction between the outer accelerated plasma sheath and the inner foam shell by preionizing the foam with the SXR emission of the near-electrode pinches.« less

Robot Hand Grips Cylinders Securely

NASA Technical Reports Server (NTRS)

Parma, George F.

1989-01-01

Jaws and linkage accommodate various sizes. Robot hand includes two pairs of parallel jaws that grasp rods, pipes, tubes, struts, and other long, heavy cylindrical objects. Hand features compact rotary drive and butterfly configuration simplifying approach and gripping maneuvers of robot. Parallelogram linkages maintain alignment of each jaw with other jaws. One bar of each linkage connected to one of two concentric, counterrotating shafts; rotation of shafts moves jaws in each pair toward or away from each other to grasp or release workpiece. Each jaw includes rigid gripping pad lined with rubber to give firm grip and to prevent damage to workpiece. Inner cylindrical surface (corner) of each jaw tapers off to flat sides. Enables jaw to grasp workpieces with diameters larger than or equal to twice the corner radius.

Analytic drain current model for III-V cylindrical nanowire transistors

NASA Astrophysics Data System (ADS)

Marin, E. G.; Ruiz, F. G.; Schmidt, V.; Godoy, A.; Riel, H.; Gámiz, F.

2015-07-01

An analytical model is proposed to determine the drain current of III-V cylindrical nanowires (NWs). The model uses the gradual channel approximation and takes into account the complete analytical solution of the Poisson and Schrödinger equations for the Γ-valley and for an arbitrary number of subbands. Fermi-Dirac statistics are considered to describe the 1D electron gas in the NWs, being the resulting recursive Fermi-Dirac integral of order -1/2 successfully integrated under reasonable assumptions. The model has been validated against numerical simulations showing excellent agreement for different semiconductor materials, diameters up to 40 nm, gate overdrive biases up to 0.7 V, and densities of interface states up to 1013eV-1cm-2 .

Temperature compensated sleeve type mirror mount

NASA Technical Reports Server (NTRS)

1973-01-01

The primary mirror of a large (26-inch diameter aperture) solar telescope was made of glass ceramic and designed with an integral hub on the back of the center of the mirror. This permits heat from the mirror to radiate off its back to a nearby cold plate. To permit mounting without high stresses, the hub was ground down to a smooth cylindrical surface 3.5 inch in diameter. The ground surface was then acid-etched to remove 0.007 inch (on the diameter) by immersion for five minutes in a mixture of four parts 92% sulfuric acid and three parts 50% hydrofluoric acid. The acid etching removes microcracks from the ground Cer-Vit surface. An Invar sleeve was fabricated to fit over the hub with about 0.010 inch radial (0.020 inch diametral) clearance.

Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves.

PubMed

Gras, Florian; Gottschling, Heiko; Schröder, Manuel; Marintschev, Ivan; Hofmann, Gunther O; Burgkart, Rainer

2016-10-01

Percutaneous iliosacral screw placement is the standard procedure for fixation of posterior pelvic ring lesions, although a transsacral screw path is being used more frequently in recent years owing to increased fracture-fixation strength and better ability to fix central and bilateral sacral fractures. However, biomorphometric data for the osseous corridors are limited. Because placement of these screws in a safe and effective manner is crucial to using transsacral screws, we sought to address precise sacral anatomy in more detail to look for anatomic variation in the general population. We asked: (1) What proportion of healthy pelvis specimens have no transsacral corridor at the level of the S1 vertebra owing to sacral dysmorphism? (2) If there is no safe diameter for screw placement in the transsacral S1 corridor, is an increased and thus safe diameter of the transsacral S2 corridor expected? (3) Are there sex-specific differences in sacral anatomy and are these correlated with known anthropometric parameters? CT scans of pelves of 280 healthy patients acquired exclusively for medical indications such as polytrauma (20%), CT angiography (70%), and other reasons (10%), were segmented manually. Using an advanced CT-based image analysis system, the mean shape of all segmented pelves was generated and functioned as a template. On this template, the cylindric transsacral osseous corridor at the level of the S1 and S2 vertebrae was determined manually. Each pelvis then was registered to the template using a free-form registration algorithm to measure the maximum screw corridor diameters on each specimen semiautomatically. Thirty of 280 pelves (11%) had no transsacral S1 corridor owing to sacral dysmorphism. The average of maximum cylindrical diameters of the S1 corridor for the remaining 250 pelves was 12.8 mm (95% CI, 12.1-13.5 mm). A transverse corridor for S2 was found in 279 of 280 pelves, with an average of maximum cylindrical diameter of 11.6 mm (95% CI, 11.3-11.9 mm). Decreasing transsacral S1 corridor diameters are correlated with increasing transsacral S2 corridor diameters (R value for females, -0.260, p < 0.01; for males, -0.311, p < 0.001). Female specimens were more likely to have sacral dysmorphism (defined as a pelvis without a transsacral osseous corridor at the level of the S1 vertebra) than were male specimens (females, 16%; males, 7%; p < 0.003). Furthermore female pelves had smaller-corridor diameters than did male pelves (females versus males for S1: 11.7 mm [95% CI, 10.6-12.8 mm] versus 13.5 mm [95% CI, 12.6-14.4 mm], p < 0.01; and for S2: 10.6 mm [95% CI, 10.1-11.1 mm] versus 12.2 mm [95% CI, 11.8-12.6 mm ], p < 0.0001). Narrow corridors and highly individual, sex-dependent variance of morphologic features of the sacrum make transsacral implant placement technically demanding. Individual preoperative axial-slice CT scan analyses and orthogonal coronal and sagittal reformations are recommended to determine the prevalence of sufficient-sized osseous corridors on both levels for safe screw placements, especially in female patients, owing to their smaller corridor diameters and higher rate of sacral dysmorphism.

Air temperature sensors: dependence of radiative errors on sensor diameter in precision metrology and meteorology

NASA Astrophysics Data System (ADS)

de Podesta, Michael; Bell, Stephanie; Underwood, Robin

2018-04-01

In both meteorological and metrological applications, it is well known that air temperature sensors are susceptible to radiative errors. However, it is not widely known that the radiative error measured by an air temperature sensor in flowing air depends upon the sensor diameter, with smaller sensors reporting values closer to true air temperature. This is not a transient effect related to sensor heat capacity, but a fluid-dynamical effect arising from heat and mass flow in cylindrical geometries. This result has been known historically and is in meteorology text books. However, its significance does not appear to be widely appreciated and, as a consequence, air temperature can be—and probably is being—widely mis-estimated. In this paper, we first review prior descriptions of the ‘sensor size’ effect from the metrological and meteorological literature. We develop a heat transfer model to describe the process for cylindrical sensors, and evaluate the predicted temperature error for a range of sensor sizes and air speeds. We compare these predictions with published predictions and measurements. We report measurements demonstrating this effect in two laboratories at NPL in which the air flow and temperature are exceptionally closely controlled. The results are consistent with the heat-transfer model, and show that the air temperature error is proportional to the square root of the sensor diameter and that, even under good laboratory conditions, it can exceed 0.1 °C for a 6 mm diameter sensor. We then consider the implications of this result. In metrological applications, errors of the order of 0.1 °C are significant, representing limiting uncertainties in dimensional and mass measurements. In meteorological applications, radiative errors can easily be much larger. But in both cases, an understanding of the diameter dependence allows assessment and correction of the radiative error using a multi-sensor technique.

Recent achievements using chemical vapor composite silicon carbide (CVC SiC)

NASA Astrophysics Data System (ADS)

Goodman, William A.; Tanaka, Clifford

2009-08-01

This annual review documents our progress towards inexpensive mass production of silicon carbide mirrors and optical structures. Results are provided for a NASA Small Business Technology Transfer (STTR) X-Ray Mirror project. Trex partnered with the University of Alabama-Huntsville Center for Advanced Optics (UAH-CAO) to develop fabrication methods for polished cylindrical and conical chemical vapor composite (CVCTM) SiC mandrels. These mandrels are envisioned as pre-forms for the replication of fused silica x-ray optics to be eventually used in the International X-Ray Observatory (IXO). CVC SiCTM offers superior high temperature stability, thermal and mechanical performance and polishability required for this precision replication process. In this program, Trex fabricated prototype mandrels with design diameters of 10.5cm, 20cm and 45cm. UAH-CAO was Trex's university partner in this effort and worked on polishing and metrology of the unusual x-ray mandrel geometries. UAH-CAO successfully developed an innovative interferometric method for measuring the CVC SiCTM x-ray mandrels based on a precision cylindrical lens system. UAH-CAO also developed finishing and polishing methods for CVC SiCTM that utilized a Zeeko IRP200 computer controlled polishing tool. The three technologies key technologies demonstrated in this program (near net shape forming of CVC SiCTM mandrels, the x-ray mandrel metrology and free-form polishing capability on CVC SiCTM) could enable cost-effective manufacture of the x-ray mandrels required for the International X-Ray Observatory (IXO).

Evaluation of collimation and imaging configuration in scintimammography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsui, B.M.W.; Frey, E.C.; Wessell, D.E.

1996-12-31

Conventional scintimammography (SM) with {sup 99m}Tc sestamibi has been limited to taking a single lateral view of the breast using a parallel-hole high resolution (LEHR) collimator. The collimator is placed close to the breast for best possible spatial resolution. However, the collimator geometry precludes imaging the breast from other views. We evaluated using a pinhole collimator instead of a LEHR collimator in SM for improved spatial resolution and detection efficiency, and to allow additional imaging views. Results from theoretical calculations indicated that pinhole collimators could be designed with higher spatial resolution and detection efficiency than LEHR when imaging small tomore » medium size breasts. The geometrical shape of the pinhole collimator allows imaging of the breasts from both the lateral and craniocaudal views. The dual-view images allow better determination of the location of the tumors within the breast and improved detection of tumors located in the medial region of the breast. A breast model that simulates the shape and composition of the breast and breast tumors with different sizes and locations was added to an existing 3D mathematical cardiac-torso (MCAT) phantom. A cylindrically shaped phantom with 10 cm diameter and spherical inserts with different sizes and {sup 99m}Tc sestamibi uptakes with respect to the background provide physical models of breast with tumors. Simulation studies using the breast and MCAT phantoms and experimental studies using the cylindrical phantom confirmed the utility of the pinhole collimator in SM for improved breast tumor detection.« less

Real-time ultrasound angiography using superharmonic dual-frequency (2.25MHz/30MHz) cylindrical array: In vitro study.

PubMed

Wang, Zhuochen; Martin, K Heath; Dayton, Paul A; Jiang, Xiaoning

2018-01-01

Recent studies suggest that dual-frequency intravascular ultrasound (IVUS) transducers allow detection of superharmonic bubble signatures, enabling acoustic angiography for microvascular and molecular imaging. In this paper, a dual-frequency IVUS cylindrical array transducer was developed for real-time superharmonic imaging. A reduced form-factor lateral mode transmitter (2.25MHz) was used to excite microbubbles effectively at 782kPa with single-cycle excitation while still maintaining the small size and low profile (5Fr) (3Fr=1mm) for intravascular imaging applications. Superharmonic microbubble responses generated in simulated microvessels were captured by the high frequency receiver (30MHz). The axial and lateral full-width half-maximum of microbubbles in a 200-μm-diameter cellulose tube were measured to be 162μm and 1039μm, respectively, with a contrast-to-noise ratio (CNR) of 16.6dB. Compared to our previously reported single-element IVUS transducers, this IVUS array design achieves a higher CNR (16.6dBvs 11dB) and improved axial resolution (162μmvs 616μm). The results show that this dual-frequency IVUS array transducer with a lateral-mode transmitter can fulfill the native design requirement (∼3-5Fr) for acoustic angiography by generating nonlinear microbubble responses as well as detecting their superharmonic responses in a 5Fr form factor. Copyright © 2017 Elsevier B.V. All rights reserved.

Novel Shapes of Miscible Interfaces Observed

NASA Technical Reports Server (NTRS)

Balasubramaniam, Ramaswamy; Rashidnia, Nasser

2001-01-01

The dynamics of miscible displacements in a cylindrical tube are being investigated experimentally and numerically, with a view to understand the complex processes that occur, for example, in enhanced oil recovery, hydrology, and filtration. We have observed complex shapes of the interface between two liquids that mix with each other when the less viscous liquid is displaced by the more viscous one in a tube. A less viscous fluid that displaces a more viscous fluid is known to propagate in the form of a "finger," and a flight experiment proposed by Maxworthy et al. to investigate the miscible-interface dynamics is currently being developed by NASA. From the current theory of miscible displacements, which was developed for a porous medium satisfying Darcy's law, it can be shown that in the absence of gravity the interface between the fluids is destabilized and thus susceptible to fingering only when a more viscous fluid is displaced by a less viscous one. Therefore, if the interface is initially flat and the more viscous fluid displaces the less viscous fluid, the interface ought to be stable and remain flat. However, numerical simulations by Chen and Meiburg for such displacement in a cylindrical tube show that the interface is unstable and a finger of the more viscous fluid is indeed formed. Preliminary experiments performed at the NASA Glenn Research Center show that not only can fingering occur when the more viscous fluid displaces a less viscous one in a cylindrical tube, but also that under certain conditions the advancing finger achieves a sinuous or snakelike shape. These experiments were performed using silicone oils in a vertical pipette of small diameter. In the initial configuration, the more viscous fluid rested on top of the less viscous one, and the interface was nominally flat. A dye was added to the upper liquid for ease of observation of the interface between the fluids. The flow was initiated by draining the lower fluid from the bottom of the pipette, at speeds less than 0.1 mm/sec.

TH-C-19A-05: Evaluation of a New Reusable 3D Dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juang, T; Adamovics, J; Oldham, M

Purpose: PRESAGE is a radiochromic plastic which has demonstrated strong potential for high resolution single-use 3D dosimetry. This study evaluates a new PRESAGE formulation (Presage-RU) in which the radiochromic response is reversible (the dosimeter optically clears after irradiation), enabling the potential for reusability. Methods: Presage-RU dose response and optical-clearing rates were evaluated in both small volume dosimeters (1×1×4.5cm) and a larger cylindrical dosimeter (8cm diameter, 4.5cm length). All dosimeters were allowed to fully optically clear in dark, room temperature conditions between irradiations. Dose response was determined by irradiating small volume samples from 0–8.0Gy and measuring change in optical density. Themore » cylindrical dosimeter was irradiated with a simple 4-field box plan (parallel opposed pairs of 4cm×4cm AP-PA beams and 2cm×4cm lateral beams) to 20Gy. High resolution 3D dosimetry was achieved utilizing optical-CT readout. Readings were tracked up to 14 days to characterize optical clearing. Results: Initial irradiation yielded a response of 0.0119△OD/(Gy*cm) while two subsequent reirradiations yielded a lower but consistent response of 0.0087△OD/(Gy*cm). Strong linearity of dose response was observed for all irradiations. In the large cylindrical dosimeter, the integral dose within the high dose region exhibited an exponential decay in signal over time (halflife= 23.9 hours), with the dosimeter effectively cleared (0.04% of the initial signal) after 10 days. Subsequent irradiation resulted in 19.5% lower initial signal but demonstrated that the exponential clearing rate remained consistent. Results of additional subsequent irradiations will also be presented. Conclusion: This work introduces a new re-usable radiochromic dosimeter (Presage-RU) compatible with high resolution (sub-millimeter) 3D dosimetry. Sensitivity of the initial radiation was observed to be slightly higher than subsequent irradiations, but the clearing time remained constant, indicating the dosimeter can be re-used after 10 days. Presage-RU has potential to dramatically improve cost-effectiveness and thereby lower the barrier for implementing comprehensive, high resolution 3D dosimetry. John Adamovics is the president of Heuris Inc., which commercializes PRESAGE.« less

Infertility associated with persistent hymen in an alpaca and a llama

PubMed Central

Tan, Rachel H.H.; Dascanio, John J.

2008-01-01

Perforation and dilation of the persistent hymen in an alpaca and a llama, detected by vaginal examination and endoscopy, was achieved by use of a sigmoidoscope and incremental dilation using cylindrical instruments to a maximum diameter of 38 mm. Outcome and subsequent fertility are dependent on length of time the obstruction has been present and secondary uterine disease. PMID:19183735

Polymer dynamics under cylindrical confinement featuring a locally repulsive surface: A quasielastic neutron scattering study.

PubMed

Krutyeva, M; Pasini, S; Monkenbusch, M; Allgaier, J; Maiz, J; Mijangos, C; Hartmann-Azanza, B; Steinhart, M; Jalarvo, N; Richter, D

2017-05-28

We investigated the effect of intermediate cylindrical confinement with locally repulsive walls on the segmental and entanglement dynamics of a polymer melt by quasielastic neutron scattering. As a reference, the corresponding polymer melt was measured under identical conditions. The locally repulsive confinement was realized by hydrophilic anodic alumina nanopores with a diameter of 20 nm. The end-to-end distance of the hydrophobic infiltrated polyethylene-alt-propylene was close to this diameter. In the case of hard wall repulsion with negligible local attraction, several simulations predicted an acceleration of segmental dynamics close to the wall. Other than in attractive or neutral systems, where the segmental dynamics is slowed down, we found that the segmental dynamics in the nanopores is identical to the local mobility in the bulk. Even under very careful scrutiny, we could not find any acceleration of the surface-near segmental motion. On the larger time scale, the neutron spin-echo experiment showed that the Rouse relaxation was not altered by confinement effects. Also the entanglement dynamics was not affected. Thus at moderate confinement conditions, facilitated by locally repulsive walls, the dynamics remains as in the bulk melt, a result that is not so clear from simulations.

Mamdani-Fuzzy Modeling Approach for Quality Prediction of Non-Linear Laser Lathing Process

NASA Astrophysics Data System (ADS)

Sivaraos; Khalim, A. Z.; Salleh, M. S.; Sivakumar, D.; Kadirgama, K.

2018-03-01

Lathing is a process to fashioning stock materials into desired cylindrical shapes which usually performed by traditional lathe machine. But, the recent rapid advancements in engineering materials and precision demand gives a great challenge to the traditional method. The main drawback of conventional lathe is its mechanical contact which brings to the undesirable tool wear, heat affected zone, finishing, and dimensional accuracy especially taper quality in machining of stock with high length to diameter ratio. Therefore, a novel approach has been devised to investigate in transforming a 2D flatbed CO2 laser cutting machine into 3D laser lathing capability as an alternative solution. Three significant design parameters were selected for this experiment, namely cutting speed, spinning speed, and depth of cut. Total of 24 experiments were performed with eight (8) sequential runs where they were then replicated three (3) times. The experimental results were then used to establish Mamdani - Fuzzy predictive model where it yields the accuracy of more than 95%. Thus, the proposed Mamdani - Fuzzy modelling approach is found very much suitable and practical for quality prediction of non-linear laser lathing process for cylindrical stocks of 10mm diameter.

PCA Based Stress Monitoring of Cylindrical Specimens Using PZTs and Guided Waves

PubMed Central

Mujica, Luis; Ruiz, Magda; Camacho, Johanatan

2017-01-01

Since mechanical stress in structures affects issues such as strength, expected operational life and dimensional stability, a continuous stress monitoring scheme is necessary for a complete integrity assessment. Consequently, this paper proposes a stress monitoring scheme for cylindrical specimens, which are widely used in structures such as pipelines, wind turbines or bridges. The approach consists of tracking guided wave variations due to load changes, by comparing wave statistical patterns via Principal Component Analysis (PCA). Each load scenario is projected to the PCA space by means of a baseline model and represented using the Q-statistical indices. Experimental validation of the proposed methodology is conducted on two specimens: (i) a 12.7 mm (1/2″) diameter, 0.4 m length, AISI 1020 steel rod, and (ii) a 25.4 mm (1″) diameter, 6m length, schedule 40, A-106, hollow cylinder. Specimen 1 was subjected to axial loads, meanwhile specimen 2 to flexion. In both cases, simultaneous longitudinal and flexural guided waves were generated via piezoelectric devices (PZTs) in a pitch-catch configuration. Experimental results show the feasibility of the approach and its potential use as in-situ continuous stress monitoring application. PMID:29194384

Incidence angle bounds for lip flow separation of three 13.97-centimeter-diameter inlets

NASA Technical Reports Server (NTRS)

Luidens, R. W.; Abbott, J. M.

1976-01-01

Low speed wind tunnel tests were conducted to establish a procedure for determining inlet-lip flow separation and to make preliminary examination of the incidence angle bounds for lip flow separation on inlets intended for the nacelles of STOL (short takeoff and landing) aircraft. Three inlets were tested. Two of the inlets had short centerbodies with lower lip area contraction ratios of 1.30 and 1.44. The third inlet had a cylindrical centerbody extended forward into the inlet throat with a lower lip area contraction ratio of 1.44. The inlets were sized to fit a 13.97 centimeter-diameter fan. For inlet throat Mach numbers less than about 0.43, the lip flow separation angle was increased by either increasing the ratio of throat velocity to freestream velocity (Vt/Vo) or by increasing the lower lip area contraction ratio. For throat Mach numbers greater than a certain value (ranging from 0.43 to 0.52), increasing throat Mach number in some cases resulted in a decrease in the lip flow separation angle. Extending a cylindrical centerbody into the inlet throat increased the flow separation angle for nearly all values of Vt/Vo.

Polymer dynamics under cylindrical confinement featuring a locally repulsive surface: A quasielastic neutron scattering study

NASA Astrophysics Data System (ADS)

Krutyeva, M.; Pasini, S.; Monkenbusch, M.; Allgaier, J.; Maiz, J.; Mijangos, C.; Hartmann-Azanza, B.; Steinhart, M.; Jalarvo, N.; Richter, D.

2017-05-01

We investigated the effect of intermediate cylindrical confinement with locally repulsive walls on the segmental and entanglement dynamics of a polymer melt by quasielastic neutron scattering. As a reference, the corresponding polymer melt was measured under identical conditions. The locally repulsive confinement was realized by hydrophilic anodic alumina nanopores with a diameter of 20 nm. The end-to-end distance of the hydrophobic infiltrated polyethylene-alt-propylene was close to this diameter. In the case of hard wall repulsion with negligible local attraction, several simulations predicted an acceleration of segmental dynamics close to the wall. Other than in attractive or neutral systems, where the segmental dynamics is slowed down, we found that the segmental dynamics in the nanopores is identical to the local mobility in the bulk. Even under very careful scrutiny, we could not find any acceleration of the surface-near segmental motion. On the larger time scale, the neutron spin-echo experiment showed that the Rouse relaxation was not altered by confinement effects. Also the entanglement dynamics was not affected. Thus at moderate confinement conditions, facilitated by locally repulsive walls, the dynamics remains as in the bulk melt, a result that is not so clear from simulations.

Investigation of the characteristics of Automatic Exposure Control (AEC) of a Computed Tomography (CT) scanner by utilising cylindrical and anthropomorphic phantoms

NASA Astrophysics Data System (ADS)

Rulaidi, W. E. P.; Huri, M. S. N.; Ng, K. H.

2017-05-01

One method to optimise the use of x-rays in CT and hence a reduction in patient dose is the application of automatic exposure control (AEC). This study measured the effective mAs, image noise and volume CT dose index (CTDIvol) as the result of changing the AEC index on a Siemens Somatom Definition 64 slices dual source CT scanner. The scans were performed on four phantoms of different geometries, namely the 16 and 32 cm cylindrical CTDI phantoms and two anthropomorphic phantoms, RANDO (20 cm effective diameter) and ATOM (19.8 cm effective diameter). Results showed that the effective mAs increased with increasing tube potential (kVp) and Quality Reference mAs (QRM), therefore increasing CTDIvol while reducing image noise. Meanwhile, no changes of radiation dose and image noise were observed when the pitch was increased. However, for the largest phantom (32 cm effective diameter), a constant effective mAs was found between 120 and 140 kVp. The same trend was also found with increasing QRM from 300 mAs to 400 mAs suggesting a certain limitation of the AEC has been reached. In conclusion, this study showed that AEC is affected by kVp and QRM but not by pitch selection. Further work is required to quantify the characteristics of the AEC system in relation to the mentioned parameters for better optimisation.

Construction of 3.6m ARIES telescope enclosure with eccentric pier at Devasthal, Nainital

NASA Astrophysics Data System (ADS)

Bangia, Tarun

Space optimized enclosure with eccentric pier for 3.6m ARIES telescope presents construction challenges at the unique observing site of Devasthal, Nainital, India. Enclosure comprises of about 16.5m diameter and 14m high insulated steel framed cylindrical dome rotating on a 14m high stationery dome supporting structure and a 24m × 12m extension structure building for accommodating aluminizing plant and ventilation system etc. Great deal of manual and mechanical excavation was carried out at the rocky site using rock breaking and JCB machines. Foundation bolts for columns of dome supporting structure and extension structure building were grouted after alignment with total station. A 7m diameter hollow cylindrical pier isolated from other structures and 1.85m eccentric with dome center designed due to space limitation at site is being casted for mounting 150 MT mass of the largest 3.6m telescope in the country. A 7m diameter template was fabricated for 3.6m pier top. Most of enclosure components are manufactured and tested in works before assembly/erection at site. Dome drive was tested with dummy loads using VVVF drive with 6 drive and 12 idler wheel assemblies at works to simulate dome weight and smooth operation before erection at site. A 4.2m wide motorized windscreen is being manufactured with a special grade synthetic fabric to withstand wind speed up to 15m/s.

De Vega Annuloplasty for Functional Tricupsid Regurgitation: Concept of Tricuspid Valve Orifice Index to Optimize Tricuspid Valve Annular Reduction

PubMed Central

Hwang, Ho Young; Chang, Hyoung Woo; Jeong, Dong Seop

2013-01-01

We evaluated long-term results of De Vega annuloplasty measured by cylindrical sizers for functional tricuspid regurgitation (FTR) and analyzed the impact of measured annular size on the late recurrence of tricuspid valve regurgitation. Between 2001 and 2011, 177 patients (57.9±10.5 yr) underwent De Vega annuloplasty for FTR. Three cylindrical sizers (actual diameters of 29.5, 31.5, and 33.5 mm) were used to reproducibly reduce the tricuspid annulus. Long-term outcomes were evaluated and risk factor analyses for the recurrence of FTR ≥3+ were performed. Measured annular diameter indexed by patient's body surface area was included in the analyses as a possible risk factor. Operative mortality occurred in 8 patients (4.5%). Ten-year overall and cardiac death-free survivals were 80.5% and 90.8%, respectively. Five and 10-yr freedom rates from recurrent FTR were 96.5% and 93.1%, respectively. Cox proportional hazard model revealed that higher indexed annular size was the only risk factor for the recurrence of FTR (P=0.006). A minimal P value approach demonstrated that indexed annular diameter of 22.5 mm/m2 was a cut-off value predicting the recurrence of FTR. De Vega annuloplasty for FTR results in low rates of recurrent FTR in the long-term. Tricuspid annulus should be reduced appropriately considering patients' body size to prevent recurrent FTR. PMID:24339705

Time history of diesel particle deposition in cylindrical dielectric barrier discharge reactors

NASA Astrophysics Data System (ADS)

Talebizadeh, P.; Rahimzadeh, H.; Ahmadi, G.; Brown, R.; Inthavong, K.

2016-12-01

Non-thermal plasma (NTP) treatment reactors have recently been developed for elimination of diesel particulate matter for reducing both the mass and number concentration of particles. The role of the plasma itself is obscured by the phenomenon of particle deposition on the reactor surface. Therefore, in this study, the Lagrangian particle transport model is used to simulate the dispersion and deposition of nano-particles in the range of 5 to 500 nm in a NTP reactor in the absence of an electric field. A conventional cylindrical dielectric barrier discharge reactor is selected for the analysis. Brownian diffusion, gravity and Saffman lift forces were included in the simulations, and the deposition efficiencies of different sized diesel particles were studied. The results show that for the studied particle diameters, the effect of Saffman lift is negligible and gravity only affects the motion of particles with a diameter of 500 nm or larger. Time histories of particle transport and deposition were evaluated for one-time injection and a continuous (multiple-time) injection. The results show that the number of deposited particles for one-time injection is identical to the number of deposited particles for multiple-time injections when adjusted with the shift in time. Furthermore, the maximum number of escaped particles occurs at 0.045 s after the injection for all particle diameters. The presented results show that some particle reduction previously ascribed to plasma treatment has ignored contributions from the surface deposition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kyakuno, Haruka, E-mail: h-kyakuno@kanagawa-u.ac.jp; Institute of Physics, Faculty of Engineering, Kanagawa University, Yokohama 221-8686; Fukasawa, Mamoru

Single-wall carbon nanotubes (SWCNTs) are a good model system that provides atomically smooth nanocavities. It has been reported that water-SWCNTs exhibit hydrophobicity depending on the temperature T and the SWCNT diameter D. SWCNTs adsorb water molecules spontaneously in their cylindrical pores around room temperature, whereas they exhibit a hydrophilic-hydrophobic transition or wet-dry transition (WDT) at a critical temperature T{sub wd} ≈ 220-230 K and above a critical diameter D{sub c} ≈ 1.4-1.6 nm. However, details of the WDT phenomenon and its mechanism remain unknown. Here, we report a systematic experimental study involving X-ray diffraction, optical microscopy, and differential scanning calorimetry.more » It is found that water molecules inside thick SWCNTs (D > D{sub c}) evaporate and condense into ice Ih outside the SWCNTs at T{sub wd} upon cooling, and the ice Ih evaporates and condenses inside the SWCNTs upon heating. On the other hand, residual water trapped inside the SWCNTs below T{sub wd} freezes. Molecular dynamics simulations indicate that upon lowering T, the hydrophobicity of thick SWCNTs increases without any structural transition, while the water inside thin SWCNTs (D < D{sub c}) exhibits a structural transition, forming an ordered ice. This ice has a well-developed hydrogen bonding network adapting to the cylindrical pores of the SWCNTs. Thus, the unusual diameter dependence of the WDT is attributed to the adaptability of the structure of water to the pore dimension and shape.« less

Asymptotics of a Class of Solutions to the Cylindrical Toda Equations

NASA Astrophysics Data System (ADS)

Tracy, Craig A.; Widom, Harold

The small t asymptotics of a class of solutions to the 2D cylindrical Toda equations is computed. The solutions, , have the representation where Kk$ are integral operators. This class includes the n-periodic cylindrical Toda equations. For n=2 our results reduce to the previously computed asymptotics of the 2D radial sinh-Gordon equation and for n=3 (and with an additional symmetry constraint) they reduce to earlier results for the radial Bullough-Dodd equation. Both of these special cases are examples of Painlevé III and have arisen in various applications. The asymptotics of are derived by computing the small t asymptotics where explicit formulas are given for the quantities ak and bk. The method consists of showing that the resolvent operator of Kk has an approximation in terms of resolvents of certain Wiener-Hopf operators, for which there are explicit integral formulas.

Assessment of First- and Second-Order Wave-Excitation Load Models for Cylindrical Substructures: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereyra, Brandon; Wendt, Fabian; Robertson, Amy

2017-03-09

The hydrodynamic loads on an offshore wind turbine's support structure present unique engineering challenges for offshore wind. Two typical approaches used for modeling these hydrodynamic loads are potential flow (PF) and strip theory (ST), the latter via Morison's equation. This study examines the first- and second-order wave-excitation surge forces on a fixed cylinder in regular waves computed by the PF and ST approaches to (1) verify their numerical implementations in HydroDyn and (2) understand when the ST approach breaks down. The numerical implementation of PF and ST in HydroDyn, a hydrodynamic time-domain solver implemented as a module in the FASTmore » wind turbine engineering tool, was verified by showing the consistency in the first- and second-order force output between the two methods across a range of wave frequencies. ST is known to be invalid at high frequencies, and this study investigates where the ST solution diverges from the PF solution. Regular waves across a range of frequencies were run in HydroDyn for a monopile substructure. As expected, the solutions for the first-order (linear) wave-excitation loads resulting from these regular waves are similar for PF and ST when the diameter of the cylinder is small compared to the length of the waves (generally when the diameter-to-wavelength ratio is less than 0.2). The same finding applies to the solutions for second-order wave-excitation loads, but for much smaller diameter-to-wavelength ratios (based on wavelengths of first-order waves).« less

Assessment of First- and Second-Order Wave-Excitation Load Models for Cylindrical Substructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereyra, Brandon; Wendt, Fabian; Robertson, Amy

2016-07-01

The hydrodynamic loads on an offshore wind turbine's support structure present unique engineering challenges for offshore wind. Two typical approaches used for modeling these hydrodynamic loads are potential flow (PF) and strip theory (ST), the latter via Morison's equation. This study examines the first- and second-order wave-excitation surge forces on a fixed cylinder in regular waves computed by the PF and ST approaches to (1) verify their numerical implementations in HydroDyn and (2) understand when the ST approach breaks down. The numerical implementation of PF and ST in HydroDyn, a hydrodynamic time-domain solver implemented as a module in the FASTmore » wind turbine engineering tool, was verified by showing the consistency in the first- and second-order force output between the two methods across a range of wave frequencies. ST is known to be invalid at high frequencies, and this study investigates where the ST solution diverges from the PF solution. Regular waves across a range of frequencies were run in HydroDyn for a monopile substructure. As expected, the solutions for the first-order (linear) wave-excitation loads resulting from these regular waves are similar for PF and ST when the diameter of the cylinder is small compared to the length of the waves (generally when the diameter-to-wavelength ratio is less than 0.2). The same finding applies to the solutions for second-order wave-excitation loads, but for much smaller diameter-to-wavelength ratios (based on wavelengths of first-order waves).« less

Segmented lasing tube for high temperature laser assembly

DOEpatents

Sawicki, Richard H.; Alger, Terry W.; Finucane, Raymond G.; Hall, Jerome P.

1996-01-01

A high temperature laser assembly capable of withstanding operating temperatures in excess of 1500.degree. C. is described comprising a segmented cylindrical ceramic lasing tube having a plurality of cylindrical ceramic lasing tube segments of the same inner and outer diameters non-rigidly joined together in axial alignment; insulation of uniform thickness surround the walls of the ceramic lasing tube; a ceramic casing, preferably of quartz, surrounding the insulation; and a fluid cooled metal jacket surrounds the ceramic casing. In a preferred embodiment, the inner surface of each of the ceramic lasing tube segments are provided with a pair of oppositely spaced grooves in the wall thereof parallel to the center axis of the segmented cylindrical ceramic lasing tube, and both of the grooves and the center axis of the segmented cylindrical ceramic lasing tube lie in a common plane, with the grooves in each ceramic lasing tube segment in circumferential alignment with the grooves in the adjoining ceramic lasing tube segments; and one or more ceramic plates, all lying in a common plane to one another and with the central axis of the segmented ceramic lasing tube, are received in the grooves to provide additional wall area in the segmented ceramic lasing tube for collision and return to ground state of metastable metal atoms within the segmented ceramic lasing tube.

Particle scavenging in a cylindrical ultrasonic standing wave field using levitated drops

NASA Astrophysics Data System (ADS)

Merrell, Tyler; Saylor, J. R.

2015-11-01

A cylindrical ultrasonic standing wave field was generated in a tube containing a flow of particles and fog. Both the particles and fog drops were concentrated in the nodes of the standing wave field where they combined and then grew large enough to fall out of the system. In this way particles were scavenged from the system, cleaning the air. While this approach has been attempted using a standing wave field established between disc-shaped transducers, a cylindrical resonator has not been used for this purpose heretofore. The resonator was constructed by bolting three Langevin transducers to an aluminum tube. The benefit of the cylindrical geometry is that the acoustic energy is focused. Furthermore, the residence time of the particle in the field can be increased by increasing the length of the resonator. An additional benefit of this approach is that tubes located downstream of the resonator were acoustically excited, acting as passive resonators that enhanced the scavenging process. The performance of this system on scavenging particles is presented as a function of particle diameter and volumetric flow rate. It is noted that, when operated without particles, the setup can be used to remove drops and shows promise for liquid aerosol retention from systems where these losses can be financially disadvantageous and/or hazardous.

Wave attenuation and mode dispersion in a waveguide coated with lossy dielectric material

NASA Technical Reports Server (NTRS)

Lee, C. S.; Chuang, S. L.; Lee, S. W.; Lo, Y. T.

1984-01-01

The modal attenuation constants in a cylindrical waveguide coated with a lossy dielectric material are studied as functions of frequency, dielectric constant, and thickness of the dielectric layer. A dielectric material best suited for a large attenuation is suggested. Using Kirchhoff's approximation, the field attenuation in a coated waveguide which is illuminated by a normally incident plane wave is also studied. For a circular guide which has a diameter of two wavelengths and is coated with a thin lossy dielectric layer (omega sub r = 9.1 - j2.3, thickness = 3% of the radius), a 3 dB attenuation is achieved within 16 diameters.

Effect of Slag Impregnation on Macroscopic Deformation of Bauxite-Based Material

NASA Astrophysics Data System (ADS)

Coulon, Antoine; De Bilbao, Emmanuel; Michel, Rudy; Bouchetou, Marie-Laure; Brassamin, Séverine; Gazeau, Camille; Zanghi, Didier; Poirier, Jacques

This work aims at studying the volume change of bauxite corroded by a molten slag. Cylindrical samples were prepared by mixing ground bauxite with slag. Optical measurement at high temperature (1450 °C) of deformation with a high-resolution camera has been developed. Image processing allowed for determining the change in diameter of the sample. We showed that the deformation was induced by the precipitation of new expansive crystallised phases observed by SEM-EDS analyses. Adding pellets of the same slag upon the samples allowed to emphasize the effect of the slag amount on the size change. The change in diameter significantly increased in the impregnated area.

RADIATION MONITOR CONTAINING TWO CONCENTRIC IONIZATION CHAMBERS AND MEANS FOR INSULATING THE SEPARATE CHAMBERS

DOEpatents

Braestrup, C.B.; Mooney, R.T.

1964-01-21

This invention relates to a portable radiation monitor containing two concentric ionization chambers which permit the use of standard charging and reading devices. It is particularly adapted as a personnel x-ray dosimeter and to this end comprises a small thin walled, cylindrical conductor forming an inner energy dependent chamber, a small thin walled, cylindrical conductor forming an outer energy independent chamber, and polymeric insulation means which insulates said chambers from each other and holds the chambers together with exposed connections in a simple, trouble-free, and compact assembly substantially without variation in directional response. (AEC)

76 FR 36092 - Small Diameter Graphite Electrodes From the People's Republic of China: Extension of Time Limit...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-21

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-929] Small Diameter Graphite... antidumping duty order on small diameter graphite electrodes from the People's Republic of China (``PRC'') for... preliminary results of this review were published on March 7, 2011. See Small Diameter Graphite Electrodes...

77 FR 6060 - Small Diameter Graphite Electrodes from the People's Republic of China: Extension of Time Limit...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-07

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-929] Small Diameter Graphite... Department) initiated an administrative review of the antidumping duty order on small diameter graphite... preliminary results of this review by 95 days until February 3, 2012. See Small Diameter Graphite Electrodes...

CYLINDRICAL WAVES OF FINITE AMPLITUDE IN DISSIPATIVE MEDIUM (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naugol'nykh, K.A.; Soluyan, S.I.; Khokhlov, R.V.

1962-07-01

Propagation of diverging and converging cylindrical waves in a nonlinear, viscous, heat conducting medium is analyzed using approximation methods. The KrylovBogolyubov method was used for small Raynold's numbers, and the method of S. I. Soluyan et al. (Vest. Mosk. Univ. ser. phys. and astronomy 3, 52-81, 1981), was used for large Raynold's numbers. The formation and dissipation of shock fronts and spatial dimensions of shock phenomena were analyzed. It is shown that the problem of finiteamplitude cylindrical wave propagation is identical to the problem of plane wave propagations in a medium with variable viscosity. (tr-auth)

STS-48 ESC image of the MODE-01 Fluid Test Article (FTA) on OV-103's middeck

NASA Technical Reports Server (NTRS)

1991-01-01

An electronic still camera (ESC) closeup shows the STS-48 Middeck Zero ('0') Gravity Dynamics Experiment 01 (MODE-01) Fluid Test Article (FTA) attached to an experimental support module (ESM) located in a forward middeck locker onboard the earth-orbiting Discovery, Orbiter Vehicle (OV) 103. The FTA is a 3.1-cm diameter cylindrical sealed Lexan tank. The FTA electromagnetic actuator has excited the test article sinusoidally, which causes the fluid inside the tank to slosh. These slosh forces, along with other data such as acceleration levels of the entire assembly, are measured by the force balance and recorded in digital form on an optical disk for later ground analysis. Crewmembers were testing the ESC as part of Development Test Objective (DTO) 648, Electronic Still Photography. The digital image was stored on a removable hard disk or small optical disk, and could be converted to a format suitable for downlink transmission. The ESC is making its initial appearance on this Space Shutt

Radiative flux from a planar multiple point source within a cylindrical enclosure reaching a coaxial circular plane

NASA Astrophysics Data System (ADS)

Tryka, Stanislaw

2007-04-01

A general formula and some special integral formulas were presented for calculating radiative fluxes incident on a circular plane from a planar multiple point source within a coaxial cylindrical enclosure perpendicular to the source. These formula were obtained for radiation propagating in a homogeneous isotropic medium assuming that the lateral surface of the enclosure completely absorbs the incident radiation. Exemplary results were computed numerically and illustrated with three-dimensional surface plots. The formulas presented are suitable for determining fluxes of radiation reaching planar circular detectors, collectors or other planar circular elements from systems of laser diodes, light emitting diodes and fiber lamps within cylindrical enclosures, as well as small biological emitters (bacteria, fungi, yeast, etc.) distributed on planar bases of open nontransparent cylindrical containers.

External combustor for gas turbine engine

DOEpatents

Santanam, Chandran B.; Thomas, William H.; DeJulio, Emil R.

1991-01-01

An external combustor for a gas turbine engine has a cyclonic combustion chamber into which combustible gas with entrained solids is introduced through an inlet port in a primary spiral swirl. A metal draft sleeve for conducting a hot gas discharge stream from the cyclonic combustion chamber is mounted on a circular end wall of the latter adjacent the combustible gas inlet. The draft sleeve is mounted concentrically in a cylindrical passage and cooperates with the passage in defining an annulus around the draft sleeve which is open to the cyclonic combustion chamber and which is connected to a source of secondary air. Secondary air issues from the annulus into the cyclonic combustion chamber at a velocity of three to five times the velocity of the combustible gas at the inlet port. The secondary air defines a hollow cylindrical extension of the draft sleeve and persists in the cyclonic combustion chamber a distance of about three to five times the diameter of the draft sleeve. The hollow cylindrical extension shields the drive sleeve from the inlet port to prevent discharge of combustible gas through the draft sleeve.

Ceramic turbine stator vane and shroud support

DOEpatents

Glenn, Robert G.

1981-01-01

A support system for supporting the stationary ceramic vanes and ceramic outer shrouds which define the motive fluid gas path in a gas turbine engine is shown. Each individual segment of the ceramic component whether a vane or shroud segment has an integral radially outwardly projecting stem portion. The stem is enclosed in a split collet member of a high-temperature alloy material having a cavity configured to interlock with the stem portion. The generally cylindrical external surface of the collet engages a mating internal cylindrical surface of an aperture through a supporting arcuate ring segment with mating camming surfaces on the two facing cylindrical surfaces such that radially outward movement of the collet relative to the ring causes the internal cavity of the collet to be reduced in diameter to tightly engage the ceramic stem disposed therein. A portion of the collet extends outwardly through the ring segment opposite the ceramic piece and is threaded for receiving a nut and a compression washer for retaining the collet in the ring segment under a continuous biasing force urging the collet radially outwardly.

Boattail juncture shaping for spin-stabilized rounds in supersonic flight

NASA Astrophysics Data System (ADS)

Jiajan, W.; Chue, R. S. M.; Nguyen, T.; Yu, S. C. M.

2015-03-01

In this paper, the effects of boattail junction shaping on aerodynamic drag and stability of supersonic spin-stabilized rounds are investigated using computational fluid dynamics. For a generic round body comprising of a secant-ogive nose, a cylindrical body and a conical boattail, the shaping technique was achieved by adding a convex surface of varying degrees of radius of curvature to the junction between the cylindrical body and the boattail. It was shown through numerical simulations that this shaping technique can provide a reduction in aerodynamic drag of up to 5.4 % without destabilizing the round bodies when the radius of curvature is less than 8.8 times the diameter of the cylindrical body. The more gradual change of the flow characteristics, e.g., the pressure over the convex surface, was identified as the main reason for the drag reduction. A unique aspect of the current work is that stability is treated as an integral part of the performance assessment. It was also found that the dynamic instability encountered at large radii of curvature is due to the Magnus effects.

Development of a cylindrical tracking detector with multichannel scintillation fibers and pixelated photon detector readout

NASA Astrophysics Data System (ADS)

Akazawa, Y.; Miwa, K.; Honda, R.; Shiozaki, T.; Chiga, N.

2015-07-01

We are developing a cylindrical tracking detector for a Σp scattering experiment in J-PARC with scintillation fibers and the Pixelated Photon Detector (PPD) readout, which is called as cylindrical fiber tracker (CFT), in order to reconstruct trajectories of charged particles emitted inside CFT. CFT works not only as a tracking detector but also a particle identification detector from energy deposits. A prototype CFT consisting of two straight layers and one spiral layer was constructed. About 1100 scintillation fibers with a diameter of 0.75 mm (Kuraray SCSF-78 M) were used. Each fiber signal was read by Multi-Pixel Photon Counter (MPPC, HPK S10362-11-050P, 1×1 mm2, 400 pixels) fiber by fiber. MPPCs were handled with Extended Analogue Silicon Photomultipliers Integrated ReadOut Chip (EASIROC) boards, which were developed for the readout of a large number of MPPCs. The energy resolution of one layer was 28% for a 70 MeV proton where the energy deposit in fibers was 0.7 MeV.

Fabrication and study of cylindrical scintillation counters of the ARES spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baranov, V.A.; Evtukhovich, P.G.; Korenchenko, S.M.

A method is described for fabricating 600 x 87 x 5 mm plastic scintillation counters which are constituent elements of a 673 mm in diameter cylindrical hodoscope. Results of investigations into the amplitude and temporal characteristics of a separate scintillation are presented. Light losses in the transitional and main lightguides were determined primarily by the absorption length of the organic glass. The time resolution of the counter with the beta source placed at the center of the scintillator equaled 1 nsec; the velocity of propagation of light in the scintillator equals 12.1 cm/nsec. The ARES spectrometer detects electrons and gammamore » rays under conditions of high meson-stopping intensity and will be used for pion and muon rare decay studies.« less

Comparison of High-Speed Operating Characteristics of Size 215 Cylindrical-Roller Bearings as Determined in Turbojet Engine and in Laboratory Test Rig

NASA Technical Reports Server (NTRS)

Macks, E Fred; Nemeth, Zolton N

1952-01-01

A comparison of the operating characteristics of 75-millimeter-bore (size 215) cylindrical-roller one-piece inner-race-riding cage-type bearings was made by means of a laboratory test rig and a turbojet engine. Cooling correlation parameters were determined by means of dimensional analysis, and the generalized results for both the inner- and the outer-race bearing operating temperatures are computed for the laboratory test rig and the turbojet engine. A method is given that enables the designer to predict the inner- and outer-race turbine roller-bearing temperatures from single curves, regardless of variations in speed, load, oil flow, oil inlet temperature, oil inlet viscosity, oil-jet diameter, or any combination of these parameters.

Microdosimetric investigation at the therapeutic proton beam facility of CATANA.

PubMed

De Nardo, L; Moro, D; Colautti, P; Conte, V; Tornielli, G; Cuttone, G

2004-01-01

Proton beams (62 Mev) are used by the Laboratori Nazionali del Sud of the Italian Institute of Nuclear Physics to treat eye melanoma tumours at the therapeutic facility called CATANA. A cylindrical slim tissue-equivalent proportional counter (TEPC) of 2.7 mm external diameter has been used to compare the radiation quality of two spread-out Bragg peaks (SOBP) at the CATANA proton beam.

Temperature changes in an initially frozen wood chip pile.

Treesearch

George R. Sampson; Jenifer H. McBeath

1987-01-01

White spruce trees and tops were chipped and placed in a pile near Fairbanks, Alaska, in February 1983. The pile was 6 meters in diameter and 6 meters high in a cylindrical shape. Thermocouples were placed at 25 locations within the pile so that temperatures could be tracked over time. Gypsum blocks were placed at 10 locations to determine changes in moisture content....

Numerical Investigation of Magnetically Driven Isentropic Compression of Solid Aluminum Cylinders with a Semi-Analytical Code

NASA Astrophysics Data System (ADS)

Largent, Billy T.

The state of matter at extremely high pressures and densities is of fundamental interest to many branches of research, including planetary science, material science, condensed matter physics, and plasma physics. Matter with pressures, or energy densities, above 1 megabar (100 gigapascal) are defined as High Energy Density (HED) plasmas. They are directly relevant to the interiors of planets such as Earth and Jupiter and to the dense fuels in Inertial Confinement Fusion (ICF) experiments. To create HEDP conditions in laboratories, a sample may be compressed by a smoothly varying pressure ramp with minimal temperature increase, following the isentropic thermodynamic process. Isentropic compression of aluminum targets has been done using magnetic pressure produced by megaampere, pulsed power currents having 100 ns rise times. In this research project, magnetically driven, cylindrical isentropic compression has been numerically studied. In cylindrical geometry, material compression and pressure become higher than in planar geometry due to geometrical effects. Based on a semi-analytical model for the Magnetized Liner Inertial Fusion (MagLIF) concept, a code called "SA" was written to design cylindrical compression experiments on the 1.0 MA Zebra pulsed power generator at the Nevada Terawatt Facility (NTF). To test the physics models in the code, temporal progresses of rod compression and pressure were calculated with SA and compared with 1-D magnetohydrodynamic (MHD) codes. The MHD codes incorporated SESAME tables, for equation of state and resistivity, or the classical Spitzer model. A series of simulations were also run to find optimum rod diameters for 1.0 MA and 1.8 MA Zebra current pulses. For a 1.0 MA current peak and 95 ns rise time, a maximum compression of 2.35 ( 6.3 g/cm3) and a pressure of 900 GPa within a 100 mum radius were found for an initial diameter of 1.05 mm. For 1.8 MA peak simulations with the same rise time, the initial diameter of 1.3 mm was optimal with 3.32 ( 9.0 g/cm 3) compression.

SU-F-I-01: Normalized Mean Glandular Dose Values for Dedicated Breast CT Using Realistic Breast-Shaped Phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez, A; Boone, J

Purpose: To estimate normalized mean glandular dose values for dedicated breast CT (DgN-CT) using breast CT-derived phantoms and compare to estimations using cylindrical phantoms. Methods: Segmented breast CT (bCT) volume data sets (N=219) were used to measure effective diameter profiles and were grouped into quintiles by volume. The profiles were averaged within each quintile to represent the range of breast sizes found clinically. These profiles were then used to generate five voxelized computational phantoms (V1, V2, V3, V4, V5 for the small to large phantom sizes, respectively), and loaded into the MCNP6 lattice geometry to simulate normalized mean glandular dosemore » coefficients (DgN-CT) using the system specifications of the Doheny-prototype bCT scanner in our laboratory. The DgN-CT coefficients derived from the bCT-derived breast-shaped phantoms were compared to those generated using a simpler cylindrical phantom using a constant volume, and the following constraints: (1) Length=1.5*radius; (2) radius determined at chest wall (Rcw), and (3) radius determined at the phantom center-of-mass (Rcm). Results: The change in Dg-NCT coefficients averaged across all phantom sizes, was - 0.5%, 19.8%, and 1.3%, for constraints 1–3, respectively. This suggests that the cylindrical assumption is a good approximation if the radius is taken at the breast center-of-mass, but using the radius at the chest wall results in an underestimation of the glandular dose. Conclusion: The DgN-CT coefficients for bCT-derived phantoms were compared against the assumption of a cylindrical phantom and proved to be essentially equivalent when the cylinder radius was set to r=1.5/L or Rcm. While this suggests that for dosimetry applications a patient’s breast can be approximated as a cylinder (if the correct radius is applied), this assumes a homogenous composition of breast tissue and the results may be different if the realistic heterogeneous distribution of glandular tissue is considered. Research reported in this paper was supported in part by the National Cancer Institute of the National Institutes of Health under award R01CA181081. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institue of Health.« less

Three Dimensionally Interlinked, Dense, Solid Form of Single-Walled CNT Ropes

NASA Technical Reports Server (NTRS)

Smalley, Richard E.

2012-01-01

A 3D networked, dense form of single-walled carbon nanotubes (SWNT) has been made through isotropic shrinking of a gel-like SWNT-water paste by very slow evaporation. Approximately 35 g of Raw HiPco nanotubes were cleaned by the method of soft baking (250 C for 15 hours in air saturated with water vapor) in a glass beaker followed by leaching with concentrated hydrochloric acid. Typically, one liter of concentrated hydrochloric acid was added to the soft-baked voluminous mass in the same large beaker, and allowed to digest at room temperature with stirring overnight. The acid-digested SWNT slurry was filtered through a large porcelain Buchner funnel under atmospheric pressure. The slurry was continuously flushed, while still in the funnel, with a very slow but steady stream of deionized water employing a peristaltic pump. This process, referred to as gwashing, h continued until the filtrate water dripping from the Buchner funnel was clear, colorless, and neutral to a pH paper. This took about 15 liters of water to flow through the slurry over a day. At this point, the water pump was stopped and the SWNT-water slurry was allowed to drain the excess water for about 10 hours. The resulting thick paste of SWNT-neutral water was transferred to a beaker. The beaker was covered with aluminum foil with few holes and allowed to dry very slowly in a hood at room temperature. In about eight weeks, the sample gradually dried isotropically to a cylindrical dense mass referred to as a carbon nanotube block (CNB). There was no carbonaceous matter sticking to any of the glass surface where the SWNT-water paste made contact. The approximate dimensions of the cylindrical SWNT block that weighed 28 g were 1.5 in. (.3.8 cm) in diameter and 1.25 in. (.3.2 cm) in height. The bottom portion of the cylinder that was in contact with the beaker surface was slightly wider, indicating some resistance to shrinking. The cylindrical mass also consisted of several pores. The cylindrical mass was very tough and could not be broken with a small hammer using considerable force. The mass of the solid could be polished over a fine grain emery paper or even a smooth, stainless steel surface indicative of alignment at finer levels.

SPECT data acquisition and image reconstruction in a stationary small animal SPECT/MRI system

NASA Astrophysics Data System (ADS)

Xu, Jingyan; Chen, Si; Yu, Jianhua; Meier, Dirk; Wagenaar, Douglas J.; Patt, Bradley E.; Tsui, Benjamin M. W.

2010-04-01

The goal of the study was to investigate data acquisition strategies and image reconstruction methods for a stationary SPECT insert that can operate inside an MRI scanner with a 12 cm bore diameter for simultaneous SPECT/MRI imaging of small animals. The SPECT insert consists of 3 octagonal rings of 8 MR-compatible CZT detectors per ring surrounding a multi-pinhole (MPH) collimator sleeve. Each pinhole is constructed to project the field-of-view (FOV) to one CZT detector. All 24 pinholes are focused to a cylindrical FOV of 25 mm in diameter and 34 mm in length. The data acquisition strategies we evaluated were optional collimator rotations to improve tomographic sampling; and the image reconstruction methods were iterative ML-EM with and without compensation for the geometric response function (GRF) of the MPH collimator. For this purpose, we developed an analytic simulator that calculates the system matrix with the GRF models of the MPH collimator. The simulator was used to generate projection data of a digital rod phantom with pinhole aperture sizes of 1 mm and 2 mm and with different collimator rotation patterns. Iterative ML-EM reconstruction with and without GRF compensation were used to reconstruct the projection data from the central ring of 8 detectors only, and from all 24 detectors. Our results indicated that without GRF compensation and at the default design of 24 projection views, the reconstructed images had significant artifacts. Accurate GRF compensation substantially improved the reconstructed image resolution and reduced image artifacts. With accurate GRF compensation, useful reconstructed images can be obtained using 24 projection views only. This last finding potentially enables dynamic SPECT (and/or MRI) studies in small animals, one of many possible application areas of the SPECT/MRI system. Further research efforts are warranted including experimentally measuring the system matrix for improved geometrical accuracy, incorporating the co-registered MRI image in SPECT reconstruction, and exploring potential applications of the simultaneous SPECT/MRI SA system including dynamic SPECT studies.

A novel optical detector concept for dedicated and multi-modality in vivo small animal imaging

NASA Astrophysics Data System (ADS)

Peter, Jörg; Schulz, Ralf B.; Unholtz, Daniel; Semmler, Wolfhard

2007-07-01

An optical detector suitable for inclusion in tomographic arrangements for non-contact in vivo bioluminescence and fluorescence imaging applications is proposed. It consists of a microlens array (MLA) intended for field-of-view definition, a large-field complementary metal-oxide-semiconductor (CMOS) chip for light detection, a septum mask for cross-talk suppression, and an exchangeable filter to block excitation light. Prototype detector units with sensitive areas of 2.5 cm x 5 cm each were assembled. The CMOS sensor constitutes a 512 x 1024 photodiode matrix at 48 μm pixel pitch. Refractive MLAs with plano-convex lenses of 480 μm in diameter and pitch were selected resulting in a 55 x 105 lens matrix. The CMOS sensor is aligned on the focal plane of the MLA at 2.15mm distance. To separate individual microlens images an opaque multi-bore septum mask of 2.1mm in thickness and bore diameters of 400 μm at 480 μm pitch, aligned with the lens pattern, is placed between MLA and CMOS. Intrinsic spatial detector resolution and sensitivity was evaluated experimentally as a function of detector-object distance. Due to its small overall dimensions such detectors can be favorably packed for tomographic imaging (optical diffusion tomography, ODT) yielding complete 2 π field-of-view coverage. We also present a design study of a device intended to simultaneously image positron labeled substrates (positron emission tomography, PET) and optical molecular probes in small animals such as mice and rats. It consists of a cylindrical allocation of optical detector units which form an inner detector ring while PET detector blocks are mounted in radial extension, those gaining complementary information in a single, intrinsically coregistered experimental data acquisition study. Finally, in a second design study we propose a method for integrated optical and magnetic resonance imaging (MRI) which yields in vivo functional/molecular information that is intrinsically registered with the anatomy of the image object.

Acoustic Emission Signals in Thin Plates Produced by Impact Damage

NASA Technical Reports Server (NTRS)

Prosser, William H.; Gorman, Michael R.; Humes, Donald H.

1999-01-01

Acoustic emission (AE) signals created by impact sources in thin aluminum and graphite/epoxy composite plates were analyzed. Two different impact velocity regimes were studied. Low-velocity (less than 0.21 km/s) impacts were created with an airgun firing spherical steel projectiles (4.5 mm diameter). High-velocity (1.8 to 7 km/s) impacts were generated with a two-stage light-gas gun firing small cylindrical nylon projectiles (1.5 mm diameter). Both the impact velocity and impact angle were varied. The impacts did not penetrate the aluminum plates at either low or high velocities. For high-velocity impacts in composites, there were both impacts that fully penetrated the plate as well as impacts that did not. All impacts generated very large amplitude AE signals (1-5 V at the sensor), which propagated as plate (extensional and/or flexural) modes. In the low-velocity impact studies, the signal was dominated by a large flexural mode with only a small extensional mode component detected. As the impact velocity was increased within the low velocity regime, the overall amplitudes of both the extensional and flexural modes increased. In addition, a relative increase in the amplitude of high-frequency components of the flexural mode was also observed. Signals caused by high-velocity impacts that did not penetrate the plate contained both a large extensional and flexural mode component of comparable amplitudes. The signals also contained components of much higher frequency and were easily differentiated from those caused by low-velocity impacts. An interesting phenomenon was observed in that the large flexural mode component, seen in every other case, was absent from the signal when the impact particle fully penetrated through the composite plates.

Fluidic assembly for an ultra-high-speed chromosome flow sorter

DOEpatents

Gray, J.W.; Alger, T.W.; Lord, D.E.

1978-11-26

A fluidic assembly for an ultra-high-speed chromosome flow sorter using a fluid drive system of high pressure in the range of 250 to 1000 psi for greater flow velocity, a nozzle with an orifice having a small ratio of length to diameter for laminar flow rates well above the critical Reynolds number for the high flow velocity, and means for vibrating the nozzle along its axis at high frequencies in a range of about 300 kHz to 800 kHz ae described. The orifice is provided with a sharp edge at its inlet, and a conical section at its outlet for a transition from a short cylindrical aperture of small length to diameter ratio to free space. Sample and sheath fluids in separte low pressure reservoirs are transferred into separate high pressure buffer reservoirs through valve means which first permit the fluids to be loaded into the buffer reservoirs under low pressure. Once loaded, the buffer reservoirs are subjected ato high pressure and valves are operated to permit the buffer reservoirs to be emptied through the nozzle under high pressure. A sensor and decision logic is positioned at the exit of the nozzle, and a charging pulse is applied to the jet when a particle reaches a position further downstream where the droplets are formed. In order to adjust the timing of charge pulses, the distance between the sensing station at the outlet of the nozzle and the droplet breakoff point is determined by stroboscopic illumination of the droplet breakoff region using a laser and a revolving lucite cylinder for breaking up the coherency of the laser, and a beam on/off modulator. The breakoff point in the region thus illuminated may then be viewed, using a television monitor.

Remote sensing and the optical properties of the narrow cylindrical leaves of Juncus roemerianus

USGS Publications Warehouse

Ramsey, Elijah W.; Rangoonwala, A.

2004-01-01

To develop a more complete foundation for remote sensing of the marsh grass Juncus roemerianus, we measured the optical properties of its cylindrical leaves at sites of different canopy height, biomass composition and amount, and connectivity to ocean flushing. To measure the leaf optical properties, we adapted a technique used for conifer needles. After establishing the reliability and limits of the adapted technique to the wider J.roemerianus leaves, mean transmittance and reflectance spectra were compared to associated leaf diameters from two dates in 1999 and 2002 and at each site. Transmittance was inversely related to leaf diameter. Mean transmittance and reflectance generated from reoccupation of many field sites in 2002 indicated little or no difference in transmittance between years, a slight reflectance difference in the visible (<2%) and a slightly higher reflectance difference in the near infrared (NIR) (<4%). Site comparison indicated limited ability to separate leaf transmittance but not reflectance by marsh type (e.g., low, medium, high) or biomass. Excluding one outlier, we found leaf transmittances could be adequately represented as 1% ?? 0.2% in the visible and 9% ?? 1% in the NIR and leaf reflectances represented from 14% to 16% in the visible and 71% to 75% in the NIR (the reflectance ranges represent 1999 and 2002 means). Reflectance and transmittance spectra associated with the dead J. roemerianus leaves displayed a spectrally flat increase from the visible to the NIR wavelengths. In total, we documented the atypical optical properties of the cylindrical J. roemerianus leaves and showed that to a first approximation, single means could represent leaf transmittance and visible leaf reflectance across all marsh zones and, after accounting for sample standardization, possibly the NIR reflectance as well.

An Asymmetric Birdcage Coil for Small-animal MR Imaging at 7T

PubMed Central

Kim, Kyoung-Nam; Han, Sang-Doc; Seo, Jeung-Hoon; Heo, Phil; Yoo, Dongkyeom; Im, Geun Ho; Lee, Jung Hee

2017-01-01

The birdcage (BC) coil is currently being utilized for uniform radiofrequency (RF) transmit/receive (Tx/Rx) or Tx-only configuration in many magnetic resonance (MR) imaging applications, but insufficient magnetic flux (|B1|) density and their non-uniform distribution still exists in high-field (HF) environments. We demonstrate that the asymmetric birdcage (ABC) transmit/receive (Tx/Rx) volume coil, which is a modified standard birdcage (SBC) coil with the end ring split into two halves, is suitable for improving the |B1| sensitivity in 7T small-animal MR imaging. Cylindrical SBC and ABC coils with 35 mm diameter were constructed and bench tested for mouse body MR imaging at 300 MHz using a 7T scanner. To assess the ABC coil performance, computational electromagnetic (EM) simulation and 7T MR experiment were performed by using a cylindrical phantom and in vivo mouse body and quantitatively compared with the SBC coil in terms of |B1| distribution, RF transmit (|B1+|) field, and signal-to-noise ratio (SNR). The bench measurements of the two BC coils are similar, yielding a quality value (Q-value) of 74.42 for the SBC coil and 77.06 for the ABC coil. The computational calculation results clearly show that the proposed ABC coil offers superior |B1| field and |B1+| field sensitivity in the central axial slice compared with the SBC coil. There was also high SNR and uniformly distributed flip angle (FA) under the loaded condition of mouse body in the 7T experiment. Although ABC geometry allows a further increase in the |B1| field and |B1+| field sensitivity in only the central axial slice, the geometrical modification of the SBC coil can make a high performance RF coil feasible in the central axial slice and also make target imaging possible in the diagonal direction. PMID:27725573

Three dimensional reconstruction of therapeutic carbon ion beams in phantoms using single secondary ion tracks

NASA Astrophysics Data System (ADS)

Reinhart, Anna Merle; Spindeldreier, Claudia Katharina; Jakubek, Jan; Martišíková, Mária

2017-06-01

Carbon ion beam radiotherapy enables a very localised dose deposition. However, even small changes in the patient geometry or positioning errors can significantly distort the dose distribution. A live, non-invasive monitoring system of the beam delivery within the patient is therefore highly desirable, and could improve patient treatment. We present a novel three-dimensional method for imaging the beam in the irradiated object, exploiting the measured tracks of single secondary ions emerging under irradiation. The secondary particle tracks are detected with a TimePix stack—a set of parallel pixelated semiconductor detectors. We developed a three-dimensional reconstruction algorithm based on maximum likelihood expectation maximization. We demonstrate the applicability of the new method in the irradiation of a cylindrical PMMA phantom of human head size with a carbon ion pencil beam of {226} MeV u-1. The beam image in the phantom is reconstructed from a set of nine discrete detector positions between {-80}^\\circ and {50}^\\circ from the beam axis. Furthermore, we demonstrate the potential to visualize inhomogeneities by irradiating a PMMA phantom with an air gap as well as bone and adipose tissue surrogate inserts. We successfully reconstructed a three-dimensional image of the treatment beam in the phantom from single secondary ion tracks. The beam image corresponds well to the beam direction and energy. In addition, cylindrical inhomogeneities with a diameter of {2.85} cm and density differences down to {0.3} g cm-3 to the surrounding material are clearly visualized. This novel three-dimensional method to image a therapeutic carbon ion beam in the irradiated object does not interfere with the treatment and requires knowledge only of single secondary ion tracks. Even with detectors with only a small angular coverage, the three-dimensional reconstruction of the fragmentation points presented in this work was found to be feasible.

Three dimensional reconstruction of therapeutic carbon ion beams in phantoms using single secondary ion tracks.

PubMed

Reinhart, Anna Merle; Spindeldreier, Claudia Katharina; Jakubek, Jan; Martišíková, Mária

2017-06-21

Carbon ion beam radiotherapy enables a very localised dose deposition. However, even small changes in the patient geometry or positioning errors can significantly distort the dose distribution. A live, non-invasive monitoring system of the beam delivery within the patient is therefore highly desirable, and could improve patient treatment. We present a novel three-dimensional method for imaging the beam in the irradiated object, exploiting the measured tracks of single secondary ions emerging under irradiation. The secondary particle tracks are detected with a TimePix stack-a set of parallel pixelated semiconductor detectors. We developed a three-dimensional reconstruction algorithm based on maximum likelihood expectation maximization. We demonstrate the applicability of the new method in the irradiation of a cylindrical PMMA phantom of human head size with a carbon ion pencil beam of [Formula: see text] MeV u -1 . The beam image in the phantom is reconstructed from a set of nine discrete detector positions between [Formula: see text] and [Formula: see text] from the beam axis. Furthermore, we demonstrate the potential to visualize inhomogeneities by irradiating a PMMA phantom with an air gap as well as bone and adipose tissue surrogate inserts. We successfully reconstructed a three-dimensional image of the treatment beam in the phantom from single secondary ion tracks. The beam image corresponds well to the beam direction and energy. In addition, cylindrical inhomogeneities with a diameter of [Formula: see text] cm and density differences down to [Formula: see text] g cm -3 to the surrounding material are clearly visualized. This novel three-dimensional method to image a therapeutic carbon ion beam in the irradiated object does not interfere with the treatment and requires knowledge only of single secondary ion tracks. Even with detectors with only a small angular coverage, the three-dimensional reconstruction of the fragmentation points presented in this work was found to be feasible.

Wind tunnel investigation of three axisymmetric cowls of different lengths at Mach numbers from 0.60 to 0.92

NASA Technical Reports Server (NTRS)

Re, Richard J.; Abeyounis, William K.

1993-01-01

Pressure distributions on three inlets having different cowl lengths were obtained in the Langley 16-Foot Transonic Tunnel. The cowl diameter ratio (highlight diameter to maximum diameter) was 0.85 and the cowl length ratios (cowl length to maximum diameter) were 0.337, 0.439, and 0.547. The cowls had identical nondimensionalized (with respect to cowl length) external geometry and identical internal geometry. The internal contraction ratio (highlight area to throat area) was 1.250. The inlets had longitudinal rows of static pressure orifices on the top and bottom (external) surfaces and on the contraction (internal) and diffuser surfaces. The afterbody was cylindrical in shape, and its diameter was equal to the maximum diameter of the cowl. Depending on the cowl configuration and free-stream Mach number, the mass-flow ratio varied between 0.27 and 0.87 during the tests. Angle of attack varied from 0 to 4.1 deg at selected Mach numbers and mass-flow ratios, and the Reynolds number varied with the Mach number from 3.2x10(exp 6) to 4.2x10(exp 6) per foot.

The radial flow method: constraints from laboratory experiments on the evolution of hydraulic properties of fractures during frictional sliding experiments

NASA Astrophysics Data System (ADS)

Kewel, M.; Renner, J.

2017-12-01

The variation of hydraulic properties during sliding events is of importance for source mechanics and analyses of the evolution in effective stresses. We conducted laboratory experiments on samples of Padang granite to elucidate the interrelation between shear displacement on faults and their hydraulic properties. The cylindrical samples of 30 mm diameter and 75 mm length were prepared with a ground sawcut, inclined 35° to the cylindrical axis and accessed by a central bore of 3 mm diameter. The conventional triaxial compression experiments were conducted at effective pressures of 30, 50, and 70 MPa at slip rates of 2×10-4 and 8×10-4 mm s-1. The nominally constant fluid pressure of 30 MPa was modulated by oscillations with an amplitude of up to 0.5 MPa. Permeability and specific storage capacity of the fault were determined using the oscillatory radial-flow method that rests on an analysis of amplitude ratio and phase shift between the oscillatory fluid pressure and the oscillatory fluid flow from and into the fault plane. This method allowed us to continuously monitor the hydraulic evolution during elastic loading and frictional sliding. The chosen oscillation period of 60 s guaranteed a resolution of hydraulic properties for slip increments as small as 20 μm. The determined hydraulic properties show a fairly uniform dependence on normal stress at hydrostatic conditions and initial elastic loading. The samples exhibited stable frictional sliding with modest strengthening with increasing strain. Since not all phase-shift values fell inside the theoretical range for purely radial pressure diffusion during frictional sliding, the records of equivalent hydraulic properties exhibit some gaps. In the phases with evaluable phase-shift values, permeability fluctuates by almost one order of magnitude over slip intervals of as little as 100 μm. We suppose that the observed fluctuations are related to comminution and reconfiguration of asperities on the fault planes that constantly alter the flow path geometry. Temporarily, the flow regime deviates from approximately radial flow and a specific direction dominates leading to one-dimensional flow. Further analytical and numerical modelling is necessary to elucidate possible flow patterns.

High pressure fiber optic sensor system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guida, Renato; Xia, Hua; Lee, Boon K

2013-11-26

The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

Thin Film Electrodes for Rare Event Detectors

NASA Astrophysics Data System (ADS)

Odgers, Kelly; Brown, Ethan; Lewis, Kim; Giordano, Mike; Freedberg, Jennifer

2017-01-01

In detectors for rare physics processes, such as neutrinoless double beta decay and dark matter, high sensitivity requires careful reduction of backgrounds due to radioimpurities in detector components. Ultra pure cylindrical resistors are being created through thin film depositions onto high purity substrates, such as quartz glass or sapphire. By using ultra clean materials and depositing very small quantities in the films, low radioactivity electrodes are produced. A new characterization process for cylindrical film resistors has been developed through analytic construction of an analogue to the Van Der Pauw technique commonly used for determining sheet resistance on a planar sample. This technique has been used to characterize high purity cylindrical resistors ranging from several ohms to several tera-ohms for applications in rare event detectors. The technique and results of cylindrical thin film resistor characterization will be presented.

Forward and backward motion of artificial helical swimmers in cylindrical channels

NASA Astrophysics Data System (ADS)

Acemoglu, Alperen; Temel, Fatma Zeynep; Yesilyurt, Serhat

2013-11-01

Motion of micro swimmers in confined geometries such as channels is important due to its relevance in in vivo medical applications such as minimally invasive surgery and drug delivery. Here, swimmers with diameters 0.8 mm and lengths 2 to 3 mm are produced with a 3D printer and cylindrical Nd2Fe14B magnets are placed inside the bodies. Rotating external magnetic field is used for the actuation of artificial swimmers. Different body and tail geometries are produced and experiments are conducted with a glycerol filled circular channel. Result demonstrate that decreasing channel diameter directly affects the forward motion of the swimmer due to the increasing drag. It is observed that step-out frequency, which defines maximum frequency at which the swimmer can establish a synchronous rotation with the external magnetic field, depends on the geometry of the swimmer and the channel diameter. There are significant differences between low and high frequency motion and forward and backward swimming. Longer tails enable higher forward velocities in high frequencies than backward ones, whereas forward and backward velocities are approximately the same at low frequencies. Furthermore backward motion is more stable than the forward one; at high frequencies, swimmers travel almost at the center of the channel for backward motion, and follow a helical trajectory near the wall during the forward motion. According to simulation results there is a flow which is induced by the rotation of the swimmer rotation that affects the swimmer's trajectory. We acknowledge the support from TUBITAK (Techonological & Research Council of Turkey) under the grant no: 111M376.

Compressible Fabry-Perot refractometer.

PubMed

Andersson, M; Eliasson, L; Pendrill, L R

1987-11-15

The use of a long, thermally stable Fabry-Perot etalon as a refractometer is considered in detail in this study of the refractive index of air. The etalon consists of two flat plates of fused silica 60 mm in diameter, with a cylindrical spacer made of Zerodur (a polycrystalline glass ceramic of extremely low thermal expansion) 200 mm long. The interferogram of light from a frequency-stabilized He-Ne laser is imaged with large-diameter mirror optics. The principal result is a demonstration of the effects of changes in atmospheric pressure on the etalon. The measured refractive-index values deviate by 2 parts in 10(7) from calculated values. Possible causes of error are considered in detail.

Tubular graphite cones.

PubMed

Zhang, Guangyu; Jiang, Xin; Wang, Enge

2003-04-18

We report the synthesis of tubular graphite cones using a chemical vapor deposition method. The cones have nanometer-sized tips, micrometer-sized roots, and hollow interiors with a diameter ranging from about 2 to several tens of nanometers. The cones are composed of cylindrical graphite sheets; a continuous shortening of the graphite layers from the interior to the exterior makes them cone-shaped. All of the tubular graphite cones have a faceted morphology. The constituent graphite sheets have identical chiralities of a zigzag type across the entire diameter, imparting structural control to tubular-based carbon structures. The tubular graphite cones have potential for use as tips for scanning probe microscopy, but with greater rigidity and easier mounting than currently used carbon nanotubes.

Cylindrical effects on Richtmyer-Meshkov instability for arbitrary Atwood numbers in weakly nonlinear regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, W. H.; He, X. T.; LCP, Institute of Applied Physics and Computational Mathematics, Beijing 100088

2012-07-15

When an incident shock collides with a corrugated interface separating two fluids of different densities, the interface is prone to Richtmyer-Meshkov instability (RMI). Based on the formal perturbation expansion method as well as the potential flow theory, we present a simple method to investigate the cylindrical effects in weakly nonlinear RMI with the transmitted and reflected cylindrical shocks by considering the nonlinear corrections up to fourth order. The cylindrical results associated with the material interface show that the interface expression consists of two parts: the result in the planar system and that from the cylindrical effects. In the limit ofmore » the cylindrical radius tending to infinity, the cylindrical results can be reduced to those in the planar system. Our explicit results show that the cylindrical effects exert an inward velocity on the whole perturbed interface, regardless of bubbles or spikes of the interface. On the one hand, outgoing bubbles are constrained and ingoing spikes are accelerated for different Atwood numbers (A) and mode numbers k'. On the other hand, for ingoing bubbles, when |A|k'{sup 3/2} Less-Than-Or-Equivalent-To 1, bubbles are considerably accelerated especially at the small |A| and k'; otherwise, bubbles are decelerated. For outgoing spikes, when |A|k' Greater-Than-Or-Equivalent-To 1, spikes are dramatically accelerated especially at large |A| and k'; otherwise, spikes are decelerated. Furthermore, the cylindrical effects have a significant influence on the amplitudes of the ingoing spike and bubble for large k'. Thus, it should be included in applications where the cylindrical effects play a role, such as inertial confinement fusion ignition target design.« less

Accuracy in contouring of small and low contrast lesions: Comparison between diagnostic quality computed tomography scanner and computed tomography simulation scanner-A phantom study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, Yick Wing, E-mail: mpr@hksh.com; Wong, Wing Kei Rebecca; Yu, Siu Ki

2012-01-01

To evaluate the accuracy in detection of small and low-contrast regions using a high-definition diagnostic computed tomography (CT) scanner compared with a radiotherapy CT simulation scanner. A custom-made phantom with cylindrical holes of diameters ranging from 2-9 mm was filled with 9 different concentrations of contrast solution. The phantom was scanned using a 16-slice multidetector CT simulation scanner (LightSpeed RT16, General Electric Healthcare, Milwaukee, WI) and a 64-slice high-definition diagnostic CT scanner (Discovery CT750 HD, General Electric Healthcare). The low-contrast regions of interest (ROIs) were delineated automatically upon their full width at half maximum of the CT number profile inmore » Hounsfield units on a treatment planning workstation. Two conformal indexes, CI{sub in}, and CI{sub out}, were calculated to represent the percentage errors of underestimation and overestimation in the automated contours compared with their actual sizes. Summarizing the conformal indexes of different sizes and contrast concentration, the means of CI{sub in} and CI{sub out} for the CT simulation scanner were 33.7% and 60.9%, respectively, and 10.5% and 41.5% were found for the diagnostic CT scanner. The mean differences between the 2 scanners' CI{sub in} and CI{sub out} were shown to be significant with p < 0.001. A descending trend of the index values was observed as the ROI size increases for both scanners, which indicates an improved accuracy when the ROI size increases, whereas no observable trend was found in the contouring accuracy with respect to the contrast levels in this study. Images acquired by the diagnostic CT scanner allow higher accuracy on size estimation compared with the CT simulation scanner in this study. We recommend using a diagnostic CT scanner to scan patients with small lesions (<1 cm in diameter) for radiotherapy treatment planning, especially for those pending for stereotactic radiosurgery in which accurate delineation of small-sized, low-contrast regions is important for dose calculation.« less

Fuel pin

DOEpatents

Christiansen, D.W.; Karnesky, R.A.; Leggett, R.D.; Baker, R.B.

1987-11-24

A fuel pin for a liquid metal nuclear reactor is provided. The fuel pin includes a generally cylindrical cladding member with metallic fuel material disposed therein. At least a portion of the fuel material extends radially outwardly to the inner diameter of the cladding member to promote efficient transfer of heat to the reactor coolant system. The fuel material defines at least one void space therein to facilitate swelling of the fuel material during fission.

Fuel pin

DOEpatents

Christiansen, David W.; Karnesky, Richard A.; Leggett, Robert D.; Baker, Ronald B.

1989-10-03

A fuel pin for a liquid metal nuclear reactor is provided. The fuel pin includes a generally cylindrical cladding member with metallic fuel material disposed therein. At least a portion of the fuel material extends radially outwardly to the inner diameter of the cladding member to promote efficient transfer of heat to the reactor coolant system. The fuel material defines at least one void space therein to facilitate swelling of the fuel material during fission.

Fuel pin

DOEpatents

Christiansen, David W.; Karnesky, Richard A.; Leggett, Robert D.; Baker, Ronald B.

1989-01-01

A fuel pin for a liquid metal nuclear reactor is provided. The fuel pin includes a generally cylindrical cladding member with metallic fuel material disposed therein. At least a portion of the fuel material extends radially outwardly to the inner diameter of the cladding member to promote efficient transfer of heat to the reactor coolant system. The fuel material defines at least one void space therein to facilitate swelling of the fuel material during fission.

Modified sine bar device measures small angles with high accuracy

NASA Technical Reports Server (NTRS)

Thekaekara, M.

1968-01-01

Modified sine bar device measures small angles with enough accuracy to calibrate precision optical autocollimators. The sine bar is a massive bar of steel supported by two cylindrical rods at one end and one at the other.

Lithium-thionyl chloride battery

NASA Astrophysics Data System (ADS)

Wong, D.; Bowden, W.; Hamilton, N.; Cubbison, D.; Dey, A. N.

1981-04-01

The main objective is to develop, fabricate, test, and deliver safe high rate lithium-thionyl chloride batteries for various U.S. Army applications such as manpack ratios and GLLD Laser Designators. We have devoted our efforts in the following major areas: (1) Optimization of the spirally wound D cell for high rate applications, (2) Development of a 3 inch diameter flat cylindrical cell for the GLLD laser designator application, and (3) Investigation of the reduction mechanism of SOCl2. The rate capability of the spirally wound D cell previously developed by us has been optimized for both the manpack radio (BA5590) battery and GLLD laser designator battery application in this program. A flat cylindrical cell has also been developed for the GLLD laser designator application. It is 3 inches in diameter and 0.9 inch in height with extremely low internal cell impedance that minimizes cell heating and polarization on the GLLD load. Typical cell capacity was found to be 18.0-19.0 Ahr with a few cells delivering up to about 21.0 Ahr on the GLLD test load. Study of the reduction mechanism of SOCl2 using electrochemical and spectroscopic techniques has also been carried out in this program which may be directly relevant to the intrinsic safety of the system.

Polymer dynamics under cylindrical confinement featuring a locally repulsive surface: A quasielastic neutron scattering study

DOE PAGES

Krutyeva, M.; Pasini, S.; Monkenbusch, M.; ...

2017-02-02

We investigated the effect of intermediate cylindrical confinement with locally repulsive walls on the segmental and entanglement dynamics of a polymer melt by quasielastic neutron scattering. As a reference, we measured the corresponding polymer melt under identical conditions. The locally repulsive confinement was realized by hydrophilic anodic alumina nanopores with a diameter of 20 nm. The end-to-end distance of the hydrophobic infiltrated polyethylene-alt-propylene was close to this diameter. In the case of hard wall repulsion with negligible local attraction, several simulations predicted an acceleration of segmental dynamics close to the wall. Other than in attractive or neutral systems, where themore » segmental dynamics is slowed down, we found that the segmental dynamics in the nanopores is identical to the local mobility in the bulk. Even under very careful scrutiny, we could not find any acceleration of the surface-near segmental motion. On the larger time scale, the neutron spin-echo experiment showed that the Rouse relaxation was not altered by confinement effects. Moreover, the entanglement dynamics was not affected. Thus at moderate confinement conditions, facilitated by locally repulsive walls, the dynamics remains as in the bulk melt, a result that is not so clear from simulations.« less

A directional cylindrical anemometer with four sets of differential pressure sensors

NASA Astrophysics Data System (ADS)

Liu, C.; Du, L.; Zhao, Z.

2016-03-01

This paper presents a solid-state directional anemometer for simultaneously measuring the speed and direction of a wind in a plane in a speed range 1-40 m/s. This instrument has a cylindrical shape and works by detecting the pressure differences across diameters of the cylinder when exposed to wind. By analyzing our experimental data in a Reynolds number regime 1.7 × 103-7 × 104, we figure out the relationship between the pressure difference distribution and the wind velocity. We propose a novel and simple solution based on the relationship and design an anemometer which composes of a circular cylinder with four sets of differential pressure sensors, tubes connecting these sensors with the cylinder's surface, and corresponding circuits. In absence of moving parts, this instrument is small and immune of friction. It has simple internal structures, and the fragile sensing elements are well protected. Prototypes have been fabricated to estimate performance of proposed approach. The power consumption of the prototype is less than 0.5 W, and the sample rate is up to 31 Hz. The test results in a wind tunnel indicate that the maximum relative speed measuring error is 5% and the direction error is no more than 5° in a speed range 2-40 m/s. In theory, it is capable of measuring wind up to 60 m/s. When the air stream goes slower than 2 m/s, the measuring errors of directions are slightly greater, and the performance of speed measuring degrades but remains in an acceptable range of ±0.2 m/s.

Systems and methods for determining strength of cylindrical structures by internal pressure loading

DOEpatents

DeTeresa, Steven John; Groves, Scott Eric; Sanchez, Roberto Joseph; Andrade, William Andrew

2015-08-04

In one embodiment, an apparatus, includes: a mandrel; an expansion cylinder, comprising: opposite first and second ends; an inner circumferential surface extending between the ends and characterized by an inner diameter, the inner circumferential surface defining a hollow cavity; an outer circumferential surface extending between the ends and characterized by an outer diameter that is greater than the inner diameter; and a plurality of slots extending from the inner circumferential surface to the outer circumferential surface and latitudinally oriented between the ends; and one or more base plates configured to engage one of the ends of the expansion cylinder. In another embodiment, a method includes: arranging an expansion cylinder inside a test cylinder; arranging a mandrel inside the expansion cylinder; applying a force to the mandrel for exerting a radial force on the expansion cylinder; and detecting one or more indicia of structural failure of the test cylinder.

Hole Quality Assessment in Drilling of Glass Microballoon/Epoxy Syntactic Foams

NASA Astrophysics Data System (ADS)

Ashrith, H. S.; Doddamani, Mrityunjay; Gaitonde, Vinayak; Gupta, Nikhil

2018-05-01

Syntactic foams reinforced with glass microballoons are used as alternatives for conventional materials in structural application of aircrafts and automobiles due to their unique properties such as light weight, high compressive strength, and low moisture absorption. Drilling is the most commonly used process of making holes for assembling structural components. In the present investigation, grey relation analysis (GRA) is used to optimize cutting speed, feed, drill diameter, and filler content to minimize cylindricity, circularity error, and damage factor. Experiments based on full factorial design are conducted using a vertical computer numerical control machine and tungsten carbide twist drills. GRA reveals that a combination of lower cutting speed, filler content, and drill diameter produces a good quality hole at optimum intermediate feed in drilling syntactic foams composites. GRA also shows that the drill diameter has a significant effect on the hole quality. Furthermore, damage on the hole exit side is analyzed using a scanning electron microscope.

On the question of instabilities upstream of cylindrical bodies

NASA Technical Reports Server (NTRS)

Morkovin, M. V.

1979-01-01

In an attempt to understand the unsteady vortical phenomena in perturbed stagnation regions of cylindrical bodies, a critical review of the theoretical and experimental evidence was made. Current theory is revealed to be incomplete, incorrect, or inapplicable to the phenomena observed experimentally. The formalistic approach via the principle of exchange of instabilities should most likely be replaced by a forced-disturbance approach. Also, many false conclusions were reached by ignoring that treatment of the base and perturbed flows in Hiemenz coordinate eta is asymptotic in nature. Almost surely the techniques of matched asymptotic expansions are expected to be used to capture correctly the diffusive and vorticity amplifying processes of the disturbances regarding the mean-flow boundary layer and outer potential field as eta and y/diameter approach infinity. The serious uncertainties in the experiments are discussed in detail.

Determination of the effects of wind-induced vibration on cylindrical beams

NASA Technical Reports Server (NTRS)

Artusa, E. A.

1991-01-01

The objective of the analysis was to determine the critical length to diameter ratio (L/Do) of a hollow, cylindrical beam subjected to wind-induced vibration. The sizes of beams ranged from 4 to 24 inches and were composed of ASTM grade A and grade B and American Petroleum Institute grade X42 steels. Calculations used maximum steady-state wind speeds of 130 mph associated with hurricane conditions possible at the Kennedy Space Center. The study examined the effect that different end support and load conditions have on the natural frequencies of the beams. Finally, methods of changing the frequency of the wind-induced vibration were examined. The conclusions drawn were that the greatest possible L/Do is achieved using welded supports and limiting the maximum applied axial and bending loads to less than 50 percent.

Cylindrical diffuser performance using a truncated plug nozzle

NASA Technical Reports Server (NTRS)

Galanga, F. L.; Mueller, T. J.

1976-01-01

Cylindrical diffuser performance for a truncated plug nozzle without external flow was tested in a blowdown wind tunnel. The nozzle was designed for an exit Mach number of 1.9 and the plug was conical in shape from the throat and converged to the axis of symmetry at an angle of 10 degrees. The diffuser section was fashioned into two 13.97 cm lengths to facilitate boring of the duct diameter and to allow for testing of two different duct lengths. A slotted hypotube was installed in the base of the diffuser to measure pressure distribution down the centerline of the diffuser. The data obtained included: the typical centerline and sidewall pressure ratio variation along the diffuser, cell pressure ratio vs overall pressure ratio for long and short diffusers and a comparison of minimum experimental cell pressure ratio vs area ratio.

Determination of the topological shape of integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria in the detergent solution by small-angle X-ray scattering.

PubMed

Hong, Xinguo; Weng, Yu-Xiang; Li, Ming

2004-02-01

The topological shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle X-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. The results indicate that the LH2 protein in aqueous solution is encapsulated by a monolayered detergent shell. The detergent-stabilized structure has the shape of an oblate plate, with a thickness of 40 A, a long axis of 110 A, and a short axis of 85 A. After correction for the detergent shell, the shape of the LH2 core is also an oblate plate with a height of 40 A, a long axis of 80 A, and a short axis of 55 A. In contrast to the cylindrical crystal structure with a height of 40 A and a diameter of 68 A, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ringlike crystal structure, with an eccentricity found to be 0.59-consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules.

Determination of the Topological Shape of Integral Membrane Protein Light-Harvesting Complex LH2 from Photosynthetic Bacteria in the Detergent Solution by Small-Angle X-Ray Scattering

PubMed Central

Hong, Xinguo; Weng, Yu-Xiang; Li, Ming

2004-01-01

The topological shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle X-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. The results indicate that the LH2 protein in aqueous solution is encapsulated by a monolayered detergent shell. The detergent-stabilized structure has the shape of an oblate plate, with a thickness of 40 Å, a long axis of 110 Å, and a short axis of 85 Å . After correction for the detergent shell, the shape of the LH2 core is also an oblate plate with a height of 40 Å, a long axis of 80 Å, and a short axis of 55 Å. In contrast to the cylindrical crystal structure with a height of 40 Å and a diameter of 68 Å, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ringlike crystal structure, with an eccentricity found to be 0.59—consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules. PMID:14747343

Inspection of the interior surface of cylindrical vessels using optic fiber shearography

NASA Astrophysics Data System (ADS)

Liu, Bin; Wei, Quan; Tu, Jun; Arola, Dwayne D.; Zhang, Dongsheng

2017-09-01

In this study, a shearography system integrated with a coherent fiber-optic illumination and a fiber-optic imaging bundle is presented to inspect the quality of the interior surface of a cylindrical vessel for safety purposes. The specific optical arrangement is designed for the inspection of a certain area at a small working distance. The optical arrangement of the system was assembled and an aluminum honeycomb sample was evaluated to demonstrate the capability of the system. The important relationship between the image quality and the working distance, as well as the field of view, is discussed. The system has been applied for the inspection of the interior surface of a cylindrical vessel. The experimental results suggest that the shearography system integrated with optical and image fibers can effectively minimize the size of the inspection device and be capable of evaluating the interior surface of cylindrical structures.

Multi-pinhole collimator design for small-object imaging with SiliSPECT: a high-resolution SPECT

NASA Astrophysics Data System (ADS)

Shokouhi, S.; Metzler, S. D.; Wilson, D. W.; Peterson, T. E.

2009-01-01

We have designed a multi-pinhole collimator for a dual-headed, stationary SPECT system that incorporates high-resolution silicon double-sided strip detectors. The compact camera design of our system enables imaging at source-collimator distances between 20 and 30 mm. Our analytical calculations show that using knife-edge pinholes with small-opening angles or cylindrically shaped pinholes in a focused, multi-pinhole configuration in combination with this camera geometry can generate narrow sensitivity profiles across the field of view that can be useful for imaging small objects at high sensitivity and resolution. The current prototype system uses two collimators each containing 127 cylindrically shaped pinholes that are focused toward a target volume. Our goal is imaging objects such as a mouse brain, which could find potential applications in molecular imaging.

Cylindrical geometry hall thruster

DOEpatents

Raitses, Yevgeny; Fisch, Nathaniel J.

2002-01-01

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

A two-electrode multichannel analyzer of charged particles with discrete outer cylindrical and flat end electrodes

NASA Astrophysics Data System (ADS)

Fishkova, T. Ya.

2017-06-01

Using computer simulation, I have determined the parameters of a multichannel analyzer of charged particles of a simple design that I have proposed having the form of a cylindrical capacitor with a discrete outer cylinder and closed ends in a wide range of simultaneously recorded energies ( E max/ E min = 100). When introducing an additional cylindrical electrode of small dimensions near the front end of the system, it is possible to improve the resolution by more than an order of magnitude in the low-energy region. At the same time, the energy resolution of the analyzer in all the above energy range is ρ = (4-6) × 10-3.

Virial series expansion and Monte Carlo studies of equation of state for hard spheres in narrow cylindrical pores

NASA Astrophysics Data System (ADS)

Mon, K. K.

2018-05-01

In this paper, the virial series expansion and constant pressure Monte Carlo method are used to study the longitudinal pressure equation of state for hard spheres in narrow cylindrical pores. We invoke dimensional reduction and map the model into an effective one-dimensional fluid model with interacting internal degrees of freedom. The one-dimensional model is extensive. The Euler relation holds, and longitudinal pressure can be probed with the standard virial series expansion method. Virial coefficients B2 and B3 were obtained analytically, and numerical quadrature was used for B4. A range of narrow pore widths (2 Rp) , Rp<(√{3 }+2 ) /4 =0.9330 ... (in units of the hard sphere diameter) was used, corresponding to fluids in the important single-file formations. We have also computed the virial pressure series coefficients B2', B3', and B4' to compare a truncated virial pressure series equation of state with accurate constant pressure Monte Carlo data. We find very good agreement for a wide range of pressures for narrow pores. These results contribute toward increasing the rather limited understanding of virial coefficients and the equation of state of hard sphere fluids in narrow cylindrical pores.

Traction-free vibrations of finite trigonal elastic cylinders.

PubMed

Heyliger, Paul R; Johnson, Ward L

2003-04-01

The unrestrained, traction-free vibrations of finite elastic cylinders with trigonal material symmetry are studied using two approaches, based on the Ritz method, which formulate the weak form of the equations of motion in cylindrical and rectangular coordinates. Elements of group theory are used to divide approximation functions into orthogonal subsets, thus reducing the size of the computational problem and classifying the general symmetries of the vibrational modes. Results for the special case of an isotropic cylinder are presented and compared with values published by other researchers. For the isotropic case, the relative accuracy of the formulations in cylindrical and rectangular coordinates can be evaluated, because exact analytical solutions are known for the torsional modes. The calculation in cylindrical coordinates is found to be more accurate for a given number of terms in the series approximation functions. For a representative trigonal material, langatate, calculations of the resonant frequencies and the sensitivity of the frequencies on each of the elastic constants are presented. The dependence on geometry (ratio of length to diameter) is briefly explored. The special case of a transversely isotropic cylinder (with the elastic stiffness C14 equal to zero) is also considered.

Stirling Engine With Radial Flow Heat Exchangers

NASA Technical Reports Server (NTRS)

Vitale, N.; Yarr, George

1993-01-01

Conflict between thermodynamical and structural requirements resolved. In Stirling engine of new cylindrical configuration, regenerator and acceptor and rejector heat exchangers channel flow of working gas in radial direction. Isotherms in regenerator ideally concentric cylinders, and gradient of temperature across regenerator radial rather than axial. Acceptor and rejector heat exchangers located radially inward and outward of regenerator, respectively. Enables substantial increase in power of engine without corresponding increase in diameter of pressure vessel.

Magnetic Fields of the Cerebral Cortex,

DTIC Science & Technology

1980-06-15

with worm gears on two separate horizontal shafts . One shaft (the declination axle ) near the end of the frame rotates the dewar. The other near the...carriage is fabricated from fiberglass or wood wherever possible. Vertical movement of the dewar is permitted by a 6 cm diameter cylindrical axle of...hardwood that runs between sets of aluminum rollers having double conical shape. The axle is supported by four strands of nylon parachute cord, each

Shaping-lathe roundup machine is key to profitable manufacturing of composite sheathing panels in Massachusetts or Maine

Treesearch

N. Springate; I. Plough; P. Koch

1978-01-01

A process is described in which a shaping-lathe headrig produces flakes of optimum geometry while rounding 8-foot peeler bolts to their maximum cylindrical diameter. The cylinders are then passed, at a rate of 5 to 7 per minute, to a veneer lathe for production of continuoua veneer, which is subsequently clipped into 4- by 8-foot sheets. Veneer cores are flaked in a...

Shaping-lathe roundup machine is key to profitable manufacture of composite sheathing panels in Massachusetts or Maine

Treesearch

Norman Springate; Peter Koch; Irving Plough

1978-01-01

A process is described in which a shaping-lathe headrig produces flakes of optimum geometry while rounding 8-foot peeler bolts to their maximum cylindrical diameter. The cylinder are then passed, at a rate of 5 to 7 per minute, to a veneer lathe for production of continuous veneer, which is Subsequently clipped into 4- by 8-foot sheet.. Veneer cores are flaked in a...

The Kinetics of Dissolution Revisited

NASA Astrophysics Data System (ADS)

Antonel, Paula S.; Hoijemberg, Pablo A.; Maiante, Leandro M.; Lagorio, M. Gabriela

2003-09-01

An experiment analyzing the kinetics of dissolution of a solid with cylindrical geometry in water is presented. The dissolution process is followed by measuring the solid mass and its size parameters (thickness and diameter) as a function of time. It is verified that the dissolution rate follows the Nernst model. Data treatment is compared with the dissolution of a spherical solid previously described. Kinetics, diffusion concepts, and polynomial fitting of experimental data are combined in this simple experiment.

Self supporting heat transfer element

DOEpatents

Story, Grosvenor Cook; Baldonado, Ray Orico

2002-01-01

The present invention provides an improved internal heat exchange element arranged so as to traverse the inside diameter of a container vessel such that it makes good mechanical contact with the interior wall of that vessel. The mechanical element is fabricated from a material having a coefficient of thermal conductivity above about 0.8 W cm.sup.-1.degree. K.sup.-1 and is designed to function as a simple spring member when that member has been cooled to reduce its diameter to just below that of a cylindrical container or vessel into which it is placed and then allowed to warm to room temperature. A particularly important application of this invention is directed to a providing a simple compartmented storage container for accommodating a hydrogen absorbing alloy.

Proposal of laser-driven automobile

NASA Astrophysics Data System (ADS)

Yabe, Takashi; Oozono, Hirokazu; Taniguchi, Kazumoto; Ohkubo, Tomomasa; Miyazaki, Sho; Uchida, Shigeaki; Baasandash, Choijil

2004-09-01

We propose an automobile driven by piston motion, which is driven by water-laser coupling. The automobile can load a solar-pumped fiber laser or can be driven by ground-based lasers. The vehicle is much useful for the use in other planet in which usual combustion engine cannot be used. The piston is in a closed system and then the water will not be exhausted into vacuum. In the preliminary experiment, we succeeded to drive the cylindrical piston of 0.2g (6mm in diameter) on top of water placed inside the acrylic pipe of 8 mm in inner diameter and the laser is incident from the bottom and focused onto the upper part of water by the lens (f=8mm) attached to the bottom edge.

Electrodeposition at room temperature of amorphous silicon and germanium nanowires in ionic liquid

NASA Astrophysics Data System (ADS)

Martineau, F.; Namur, K.; Mallet, J.; Delavoie, F.; Endres, F.; Troyon, M.; Molinari, M.

2009-11-01

The electrodeposition at room temperature of silicon and germanium nanowires from the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P1,4) containing SiCl4 as Si source or GeCl4 as Ge source is investigated by cyclic voltammetry. By using nanoporous polycarbonate membranes as templates, it is possible to reproducibly grow pure silicon and germanium nanowires of different diameters. The nanowires are composed of pure amorphous silicon or germanium. The nanowires have homogeneous cylindrical shape with a roughness of a few nanometres on the wire surfaces. The nanowires' diameters and lengths well match with the initial membrane characteristics. Preliminary photoluminescence experiments exhibit strong emission in the near infrared for the amorphous silicon nanowires.

The development of an 85-kW (thermal) steam Rankine solar receiver

NASA Technical Reports Server (NTRS)

Wright, C. C.; Bank, H.

1981-01-01

The receiver is a once-through monotube boiler designed for steam/electric and process steam applications at pressures up to 17.24 MPa (2500 psia) and temperatures up to 704 C (1300 F). The unit is 76.2 cm (30.0 in.) in diameter and 95.8 cm (37.7 in.) in length; it weighs 220 kg (485 lb). Its heat transfer surface, which is 45.7 cm (18 in.) in diameter by 57 cm (22.4 in.) long, is an Inconel 625, cylindrical, tube-coil assembly composed of primary and reheat sections. A test unit was successfully operated at up to 6.9 MPa (1000 psia) and 704 C (1300 F) with solar input from a 11-m-dia parabolic dish concentrator.

Final bubble lengths for aqueous foam coarsened in a horizontal cylinder

NASA Astrophysics Data System (ADS)

Sebag, V.; Roth, A. E.; Durian, D. J.

2011-12-01

We report on length statistics measured for bubbles in the equilibrium bamboo state, achieved by the coarsening of aqueous foam in long cylindrical tubes, such that the soap films are all flat and perpendicular to the axis of the tube. The average bubble length is found to be 0.88 times the tube diameter, independent of variation of the liquid filling fraction by a factor of nearly three. The actual distribution is well-approximated by a shifted Rayleigh form, with a minimum bubble size of 0.28 tube diameters. And, perhaps surprisingly, no correlations are found in the lengths of neighboring bubbles. The observed length distribution agrees with that of Fortes et al. for short bubbles, but not for long bubbles.

Calibration Tunnel for High Speed

NASA Technical Reports Server (NTRS)

Pretsch, J.

1946-01-01

For the nvestigation of measuring instruments at higher speeds up to a Mach number 0.7 a tunnel with closed test section was built in 1942 which was as simple and cheap as possble. The blower was a radial blower with straight sheet vanes of 800-millimeter diameter the tips of which were bent backward a little. The blower sucks the air through a honeycomb of diameter 1.2 neter with wide meshes. The air is then accelerated in a short cone with smooth transition to the test section. The cylindrical test section of 200-milimeter diameter has two windows (which are displaced 180 deg from each other. The instruments may be introduced and observed through and observed through these windows. . The cross section is then enlarged by a straight diffuser 3.5 meters long and reaches the ninefold cross section. The air flows back into the room through a disk diffuser of 2-meter diameter. The maximum speed in the jet is 250 m/s for a drive power of 35 kT., if there are no installations in the jet. The velocity is determined by pressure holed along the test section.

A study on plant root apex morphology as a model for soft robots moving in soil

PubMed Central

Pugno, Nicola Maria; Mazzolai, Barbara

2018-01-01

Plants use many strategies to move efficiently in soil, such as growth from the tip, tropic movements, and morphological changes. In this paper, we propose a method to translate morphological features of Zea mays roots into a new design of soft robots that will be able to move in soil. The method relies on image processing and curve fitting techniques to extract the profile of Z. mays primary root. We implemented an analytic translation of the root profile in a 3D model (CAD) to fabricate root-like probes by means of 3D printing technology. Then, we carried out a comparative analysis among the artificial root-like probe and probes with different tip shapes (cylindrical, conical, elliptical, and parabolic) and diameters (11, 9, 7, 5, and 3 mm). The results showed that the energy consumption and the penetration force of the bioinspired probe are better with respect to the other shapes for all the diameters of the developed probes. For 100 mm of penetration depth and 7 mm of probe diameter, the energy consumption of the bioinspired probe is 89% lesser with respect to the cylindrical probe and 26% lesser with respect to the conical probe. The penetration performance of the considered tip shapes was evaluated also by means of numerical simulations, obtaining a good agreement with the experimental results. Additional investigations on plant root morphology, movement strategies, and material properties can allow the development of innovative bioinspired solutions exploitable in challenging environments. This research can bring to breakthrough scenarios in different fields, such as exploration tasks, environmental monitoring, geotechnical studies, and medical applications. PMID:29874267

The Efficiency of Small Bearings in Instruments of the Type Used in Aircraft

NASA Technical Reports Server (NTRS)

Norton, F H

1921-01-01

This report deals with the construction and properties of bearings and pivots for use in instruments. The static and running friction for both thrust and radial loads was determined for a number of conical pivots and cylindrical and ball bearings. The static rocking friction was also measured for several conical and ball bearings under a heavy load, especially to determine their suitability for use in N. P. L. (National Physical Laboratory) type wind tunnel balance. In constructing conical pivots and sockets it was found that the pivots should be hardened and highly polished, preferably with a revolving lap, and that the sockets should be made by punching with a hardened and polished punch. It was found that for a light load the conical pivots give less friction than any other type, and their wearing qualities when hardened are excellent. Very small ball bearings are unsatisfactory because the proportional accuracy of the balls and races is not high enough to insure smooth running. For rocking pivots under heavy loads it was found that a ball-and-socket bearing, consisting of a hemispherical socket and a sphere of smaller diameter concentric with it, with a row of small balls resting between the two, was superior to a pivot resting in a socket. It was found that vibration such as occurs in an airplane will greatly reduce the static friction of a pivot or bearing, in some cases to as little as one-twentieth of its static value.

Two-dimensional radial laser scanning for circular marker detection and external mobile robot tracking.

PubMed

Teixidó, Mercè; Pallejà, Tomàs; Font, Davinia; Tresanchez, Marcel; Moreno, Javier; Palacín, Jordi

2012-11-28

This paper presents the use of an external fixed two-dimensional laser scanner to detect cylindrical targets attached to moving devices, such as a mobile robot. This proposal is based on the detection of circular markers in the raw data provided by the laser scanner by applying an algorithm for outlier avoidance and a least-squares circular fitting. Some experiments have been developed to empirically validate the proposal with different cylindrical targets in order to estimate the location and tracking errors achieved, which are generally less than 20 mm in the area covered by the laser sensor. As a result of the validation experiments, several error maps have been obtained in order to give an estimate of the uncertainty of any location computed. This proposal has been validated with a medium-sized mobile robot with an attached cylindrical target (diameter 200 mm). The trajectory of the mobile robot was estimated with an average location error of less than 15 mm, and the real location error in each individual circular fitting was similar to the error estimated with the obtained error maps. The radial area covered in this validation experiment was up to 10 m, a value that depends on the radius of the cylindrical target and the radial density of the distance range points provided by the laser scanner but this area can be increased by combining the information of additional external laser scanners.

Influence of Implant Shape (Tapered vs Cylindrical) on the Survival of Dental Implants Placed in the Posterior Maxilla: A Systematic Review.

PubMed

Alshehri, Mohammed; Alshehri, Fahad

2016-12-01

The aim of this review was to assess the effect of implant shape (tapered vs cylindrical) on the survival of dental implants placed in the posterior maxilla. Databases were searched from 1977 up to and including February 2015 using various key words. Only original clinical studies were included. Experimental studies, letters to the editor, review articles, case reports, and unpublished literature were excluded. The pattern of the present review was customized to mainly summarize the relevant information. Five studies were included. The number of patients included ranged between 4 and 29 participants. In total, 7 to 72 implants were placed in the posterior maxilla. Tapered and cylindrical shaped implants were placed in 1 and 1 study, respectively. In 1 study, both 41 tapered and cylindrical implant were placed. In all studies, rough-surfaced and threaded implants were used. Three studies reported the diameter and lengths of implants placed, which ranged between 3.75 to 4 mm and 10 to 20 mm, respectively. The mean follow-up period and survival rate of implants ranged between 19 and 96 months and 84.2% to 100%, respectively. In 1 study, implants were placed subcrestally in the posterior maxilla. Guided bone regeneration was performed in none of the studies. In all studies, participants were nonsmokers and were systemically healthy. There is no influence of implant shape on the survival of implants placed in the posterior maxilla.

Selective control of small versus large diameter axons using infrared laser light (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lothet, Emilie H.; Shaw, Kendrick M.; Horn, Charles C.; Lu, Hui; Wang, Yves T.; Jansen, E. Duco; Chiel, Hillel J.; Jenkins, Michael W.

2016-03-01

Sensory information is conveyed to the central nervous system via small diameter unmyelinated fibers. In general, smaller diameter axons have slower conduction velocities. Selective control of such fibers could create new clinical treatments for chronic pain, nausea in response to chemo-therapeutic agents, or hypertension. Electrical stimulation can control axonal activity, but induced axonal current is proportional to cross-sectional area, so that large diameter fibers are affected first. Physiologically, however, synaptic inputs generally affect small diameter fibers before large diameter fibers (the size principle). A more physiological modality that first affected small diameter fibers could have fewer side effects (e.g., not recruiting motor axons). A novel mathematical analysis of the cable equation demonstrates that the minimum length along the axon for inducing block scales with the square root of axon diameter. This implies that the minimum length along an axon for inhibition will scale as the square root of axon diameter, so that lower radiant exposures of infrared light will selectively affect small diameter, slower conducting fibers before those of large diameter. This prediction was tested in identified neurons from the marine mollusk Aplysia californica. Radiant exposure to block a neuron with a slower conduction velocity (B43) was consistently lower than that needed to block a faster conduction velocity neuron (B3). Furthermore, in the vagus nerve of the musk shrew, lower radiant exposure blocked slow conducting fibers before blocking faster conducting fibers. Infrared light can selectively control smaller diameter fibers, suggesting many novel clinical treatments.

Apparatus for measuring surface particulate contamination

DOEpatents

Woodmansee, Donald E.

2002-01-01

An apparatus for measuring surface particulate contamination includes a tool for collecting a contamination sample from a target surface, a mask having an opening of known area formed therein for defining the target surface, and a flexible connector connecting the tool to the mask. The tool includes a body portion having a large diameter section defining a surface and a small diameter section extending from the large diameter section. A particulate collector is removably mounted on the surface of the large diameter section for collecting the contaminants. The tool further includes a spindle extending from the small diameter section and a spool slidingly mounted on the spindle. A spring is disposed between the small diameter section and the spool for biasing the spool away from the small diameter section. An indicator is provided on the spindle so as to be revealed when the spool is pressed downward to compress the spring.

Room temperature synthesis and optical properties of small diameter (5 nm) ZnO nanorod arrays.

PubMed

Cho, Seungho; Jang, Ji-Wook; Lee, Jae Sung; Lee, Kun-Hong

2010-10-01

We report a simple wet-chemical synthesis of ∼5 nm diameter ZnO nanorod arrays at room temperature (20 °C) and normal atmospheric pressure (1 atm) and their optical properties. They were single crystalline in nature, and grew in the [001] direction. These small diameter ZnO nanorod arrays can also be synthesized at 0 °C. Control experiments were also conducted. On the basis of the results, we propose a mechanism for the spontaneous growth of the small diameter ZnO structures. The optical properties of the 5 nm diameter ZnO nanorod arrays synthesized using this method were probed by UV-Visible diffuse reflectance spectroscopy. A clear blue-shift, relative to the absorption band from 50 nm diameter ZnO nanorod arrays, was attributed to the quantum confinement effects caused by the small nanocrystal size in the 5 nm diameter ZnO nanorods.

Electromagnetic coupling to centimeter-scale mechanical membrane resonators via RF cylindrical cavities

NASA Astrophysics Data System (ADS)

Martinez, Luis A.; Castelli, Alessandro R.; Delmas, William; Sharping, Jay E.; Chiao, Raymond

2016-11-01

We present experimental and theoretical results for the excitation of a mechanical oscillator via radiation pressure with a room-temperature system employing a relatively low-(Q) centimeter-size mechanical oscillator coupled to a relatively low-Q standard three-dimensional radio-frequency (RF) cavity resonator. We describe the forces giving rise to optomechanical coupling using the Maxwell stress tensor and show that nanometer-scale displacements are possible and experimentally observable. The experimental system is composed of a 35 mm diameter silicon nitride membrane sputtered with a 300 nm gold conducting film and attached to the end of a RF copper cylindrical cavity. The RF cavity is operated in its {{TE}}011 mode and amplitude modulated on resonance with the fundamental drum modes of the membrane. Membrane motion is monitored using an unbalanced, non-zero optical path difference, optically filtered Michelson interferometer capable of measuring sub-nanometer displacements.

Thermal radiation characteristics of nonisothermal cylindrical enclosures using a numerical ray tracing technique

NASA Technical Reports Server (NTRS)

Baumeister, Joseph F.

1990-01-01

Analysis of energy emitted from simple or complex cavity designs can lead to intricate solutions due to nonuniform radiosity and irradiation within a cavity. A numerical ray tracing technique was applied to simulate radiation propagating within and from various cavity designs. To obtain the energy balance relationships between isothermal and nonisothermal cavity surfaces and space, the computer code NEVADA was utilized for its statistical technique applied to numerical ray tracing. The analysis method was validated by comparing results with known theoretical and limiting solutions, and the electrical resistance network method. In general, for nonisothermal cavities the performance (apparent emissivity) is a function of cylinder length-to-diameter ratio, surface emissivity, and cylinder surface temperatures. The extent of nonisothermal conditions in a cylindrical cavity significantly affects the overall cavity performance. Results are presented over a wide range of parametric variables for use as a possible design reference.

Experimental study of the nonlinear diffusion of a magnetic field and skin explosion of cylindrical conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chaikovsky, S. A.; Datsko, I. M.; Labetskaya, N. A.

The paper presents the results of an experimental study of the skin explosion of cylindrical conductors of diameter 1–3 mm (copper, aluminum, titanium, steel 3, and stainless steel) at a peak magnetic field of 200–600 T. The experiments were carried out on the MIG pulsed power generator at a current of up to 2.5 MA and a current rise time of 100 ns. The surface explosion of a conductor was identified by the appearance of a flash of extreme ultraviolet radiation. A minimum magnetic induction has been determined below which no plasma is generated at the conductor surface. For copper, aluminum, steel 3,more » titanium, and stainless steel, the minimum magnetic induction has been estimated to be (to within 10%) 375, 270, 280, 220, and 245 T, respectively.« less

Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

DOE PAGES

Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; ...

2015-11-19

In this study, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ~600 kA with ~200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. As amore » result, this technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.« less

Postbuckling behavior of axially compressed graphite-epoxy cylindrical panels with circular holes

NASA Technical Reports Server (NTRS)

Knight, N. F., Jr.; Starnes, J. H., Jr.

1984-01-01

The results of an experimental and analytical study of the effects of circular holes on the postbuckling behavior of graphite-epoxy cylindrical panels loaded in axial compression are presented. The STAGSC-1 general shell analysis computer code is used to determine the buckling and postbuckling response of the panels. The loaded, curved ends of the specimens were clamped by fixtures and the unloaded, straight edges were simply supported by knife-edge restraints. The panels are loaded by uniform end shortening to several times the end shortening at buckling. The unstable equilibrium path of the postbuckling response is obtained analytically by using a method based on controlling an equilibrium-path-arc-length parameter instead of the traditional load parameter. The effects of hole diameter, panel radius, and panel thickness on postbuckling response are considered in the study. Experimental results are compared with the analytical results and the failure characteristics of the graphite-epoxy panels are described.

Lineal energy calibration of mini tissue-equivalent gas-proportional counters (TEPC)

NASA Astrophysics Data System (ADS)

Conte, V.; Moro, D.; Grosswendt, B.; Colautti, P.

2013-07-01

Mini TEPCs are cylindrical gas proportional counters of 1 mm or less of sensitive volume diameter. The lineal energy calibration of these tiny counters can be performed with an external gamma-ray source. However, to do that, first a method to get a simple and precise spectral mark has to be found and then the keV/μm value of this mark. A precise method (less than 1% of uncertainty) to identify this markis described here, and the lineal energy value of this mark has been measured for different simulated site sizes by using a 137Cs gamma source and a cylindrical TEPC equipped with a precision internal 244Cm alpha-particle source, and filled with propane-based tissue-equivalent gas mixture. Mini TEPCs can be calibrated in terms of lineal energy, by exposing them to 137Cesium sources, with an overall uncertainty of about 5%.

Thin plastic foil X-ray optics with spiral geometry

NASA Astrophysics Data System (ADS)

Barbera, Marco; Mineo, Teresa; Perinati, Emanuele; Schnopper, Herbert W.; Taibi, Angelo

2007-09-01

Winding a plastic foil ribbon into spiral cylinder or spiral cones we can design and build single or multiple reflection X-ray grazing incidence focusing optics with potential applications in Astronomy as well as experimental physics. The use of thin plastic foils from common industrial applications and of a mounting technique which does not require the construction of mandrels make these optics very cost effective. A spiral geometry focusing optic produces an annular image of a point source with the angular size of the annulus depending mainly on the pitch of the winding and the focal length. We use a ray-tracing code to evaluate the performances of cylindrical, and double conical spiral geometry as a function of the design parameters e.g. focal length, diameter, optic length. Some preliminary results are presented on X-ray imaging tests performed on spiral cylindrical optics.

Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

NASA Astrophysics Data System (ADS)

Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Lau, Y. Y.; Gilgenbach, R. M.

2015-11-01

In this work, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ˜600 kA with ˜200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. This technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.

Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.

In this study, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ~600 kA with ~200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. As amore » result, this technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.« less

78 FR 56864 - Small Diameter Graphite Electrodes From the People's Republic of China: Affirmative Final...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-16

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-929] Small Diameter Graphite... (Department) determines that imports from the People's Republic of China (PRC) of graphite electrodes... Act of 1930, as amended (the Act).\\1\\ \\1\\ See Antidumping Duty Order: Small Diameter Graphite...

Collisional disruption of porous weak sintered targets at low impact velocity

NASA Astrophysics Data System (ADS)

Setoh, M.; Nakamura, A. M.; Hirata, N.; Hiraoka, K.; Arakawa, M.

Porous structure is common in asteroids and satellites of outer planets In order to study the relation between structure of the small bodies and their thermal and collisional evolution we prepared porous sintered targets measured the compressive strength and determined their impact strength Previous studies showed using sintered glass beads Love et al 1993 the targets with higher compressive strength have higher impact strength and the targets with higher porosity have higher impact strength However in these experiments the porosity of the targets were changed according to the compressive strength Therefore we fixed the porosity while the compressive strength was varied Our experiments were performed with low impact velocity condition because low impact velocities are common among icy bodies far from the Earth We sintered soda lime glass beads of 50 micron diameter and 2 5g cm -3 nominal density at various temperatures and durations to produce targets with similar porosity sim 40 and different compressive strength 0 2 sim 7 8MPa We performed impact disruption experiments using a low velocity light-gas gun at Kobe University sim 100m s We used cylindrical polycarbonate projectiles 1 5 cm in height and 1 0 cm in diameter We determined the specific energy J kg of projectile kinetic energy per kilo gram initial target mass for the condition that the largest fragment mass being the half of the initial target mass is the threshold energy for collisional disruption Q Fujiwara et al 1989 Holsapple et al

Isolation, cryotomography, and three-dimensional reconstruction of centrioles.

PubMed

Guichard, Paul; Hamel, Virginie; Neves, Aitana; Gönczy, Pierre

2015-01-01

Centrioles and basal bodies (referred to hereafter as centrioles for simplicity) are microtubule-based cylindrical organelles that are typically ∼450-nm long and ∼250nm in diameter. The centriole is composed of three distinct regions: the distal part characterized by microtubule doublets, the central core that harbors microtubule triplets, which are also present in the proximal part that also contains the cartwheel, a structure crucial for centriole assembly. The cartwheel was initially revealed by conventional electron microscopy of resin-embedded samples and is thought to impart the near universal ninefold symmetry of centrioles. Deciphering the native architecture of the cartwheel has proven challenging owing to its small dimensions and the difficulties in isolating it. Here, we present a method to purify and analyze the structure of the exceptionally long Trichonympha centriole by cryotomography and subtomogram averaging. Using this method, we revealed the native architecture of the proximal cartwheel-containing region at ∼40Å-resolution. This method can be applied as a general strategy for uncovering the structure of centrioles in other species. Copyright © 2015 Elsevier Inc. All rights reserved.

Enlargement and contracture of C2-ceramide channels.

PubMed

Siskind, Leah J; Davoody, Amirparviz; Lewin, Naomi; Marshall, Stephanie; Colombini, Marco

2003-09-01

Ceramides are known to play a major regulatory role in apoptosis by inducing cytochrome c release from mitochondria. We have previously reported that ceramide, but not dihydroceramide, forms large and stable channels in phospholipid membranes and outer membranes of isolated mitochondria. C(2)-ceramide channel formation is characterized by conductance increments ranging from <1 to >200 nS. These conductance increments often represent the enlargement and contracture of channels rather than the opening and closure of independent channels. Enlargement is supported by the observation that many small conductance increments can lead to a large decrement. Also the initial conductances favor cations, but this selectivity drops dramatically with increasing total conductance. La(+3) causes rapid ceramide channel disassembly in a manner indicative of large conducting structures. These channels have a propensity to contract by a defined size (often multiples of 4 nS) indicating the formation of cylindrical channels with preferred diameters rather than a continuum of sizes. The results are consistent with ceramides forming barrel-stave channels whose size can change by loss or insertion of multiple ceramide columns.

Cryotherapy simulator for localized prostate cancer.

PubMed

Hahn, James K; Manyak, Michael J; Jin, Ge; Kim, Dongho; Rewcastle, John; Kim, Sunil; Walsh, Raymond J

2002-01-01

Cryotherapy is a treatment modality that uses a technique to selectively freeze tissue and thereby cause controlled tissue destruction. The procedure involves placement of multiple small diameter probes through the perineum into the prostate tissue at selected spatial intervals. Transrectal ultrasound is used to properly position the cylindrical probes before activation of the liquid Argon cooling element, which lowers the tissue temperature below -40 degrees Centigrade. Tissue effect is monitored by transrectal ultrasound changes as well as thermocouples placed in the tissue. The computer-based cryotherapy simulation system mimics the major surgical steps involved in the procedure. The simulated real-time ultrasound display is generated from 3-D ultrasound datasets where the interaction of the ultrasound with the instruments as well as the frozen tissue is simulated by image processing. The thermal and mechanical simulations of the tissue are done using a modified finite-difference/finite-element method optimized for real-time performance. The simulator developed is a part of a comprehensive training program, including a computer-based learning system and hands-on training program with a proctor, designed to familiarize the physician with the technique and equipment involved.

Deformation Behavior and TExture Evolution of Steel Alloys under Axial-Torsional Loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siriruk, A.; Kant, M.; Penumadu, D.

2011-06-01

Using hollow cylinder samples with suitable geometry obtained from round bar stock, the deformation behavior of bcc Fe based 12L14 steel alloy is evaluated under multi-axial conditions. A stacked strain gage rosette and extensometer mounted on the cylindrical surface at the mid height of the specimen provided strain tensor as a function of applied stress for pure tensile and torsion tests prior to yielding. This study examines elastic and yield behavior and effects of these with respect to texture evolution. Hollow cylinder specimen geometry (tubes) with small wall thickness and relatively (to its thickness) large inner diameter is used. Themore » variation of observed yield surface in deviatoric plane and the effect on mode of deformation (tension versus torsion versus its combination) on stress-strain behavior is discussed. Bulk texture was studied using neutron time-of-flight diffractometer at High-Pressure-Preferred Orientation (HIPPO) - Los Alamos Neutron Science Center (LANSCE) instrument and the evolution of texture and related anisotropy for pure tension versus torsion are also included.« less

The formation of spikes in the displacement of miscible fluids

NASA Technical Reports Server (NTRS)

Rashidnia, N.; Balasubramaniam, R.; Schroer, R. T.

2004-01-01

We report on experiments in which a more viscous fluid displaces a less viscous one in a vertical cylindrical tube. These experiments were performed using silicone oils in a vertical pipette of small diameter. The more viscous fluid also had a slightly larger density than the less viscous fluid. In the initial configuration, the fluids were at rest, and the interface was nominally flat. A dye was added to the more viscous fluid for ease of observation of the interface between the fluids. The flow was initiated by pumping the more viscous fluid into the less viscous one. The displacement velocity was such that the Reynolds number was smaller than unity and the Peclet number for mass transfer between the fluids was large compared to unity. For upward displacement of the more viscous fluid from an initially stable configuration, an axisymmetric finger was observed under all conditions. However, a needle-shaped spike was seen to propagate from the main finger in many cases, similar to that observed by Petitjeans and Maxworthy for the displacement of a more viscous fluid by a less viscous one.

Electron Microscopic Observations of Rabbit Antibodies.

PubMed

Hall, C E; Nisonoff, A; Slayter, H S

1959-12-01

Electron micrographs were obtained showing the individual, shadow-cast macromolecules from solutions of purified anti-p-azobenzoate rabbit antibody and of normal gamma-globulin. The two materials look alike and consist mainly of asymmetrical rod-like particles about 30 to 40 A in diameter. Lengths are not constant but the weight average is about 250 A for the antibodies and about 200 A for the gamma-globulin. The average observed dimensions are reasonably consistent with values deduced from physical-chemical methods, although the shape is more nearly that of a cylindrical rod rather than the ellipsoid employed in hydrodynamical theory. Mixtures of antibody and specific dihaptenic dye were examined in attempts to establish the mode of the specific aggregation. At the high dilutions necessary for electron microscopy (0.1 mg./ml.), the effect of the dye was small and tended to be masked by non-specific aggregation on drying. The evidence suggests that under these conditions the specific reaction involves an end-to-end aggregation of the elementary particles to produce a weight average length about twice that of the pure antibody.

A high-current rail-type gas switch with preionization by an additional corona discharge

NASA Astrophysics Data System (ADS)

Antipov, E. I.; Belozerov, O. S.; Krastelev, E. G.

2016-12-01

The characteristics of a high-current rail-type gas switch with preionization of the gas (air) in a spark gap by an additional corona discharge are investigated. The experiments were performed in a voltage range of 10-45 kV using a two-electrode switch consisting of two cylindrical electrodes with a diameter of 22 mm and a length of 100 mm and a set of laterally located corona-discharge needles. The requirements for the position and size of the needles are defined for which a corona discharge is ignited before a breakdown of the main gap and does not change to a sparking form, and the entire length of the rail electrodes is efficiently used. The fulfillment of these requirements ensures stable operation of the switch with a small variation of the pulse breakdown voltage, which is not more than 1% for a fixed voltage-pulse rise time in the range from 150 ns to 3.5 μs. A short delay time of the switch breakdown makes it possible to control the two-electrode switch by an overvoltage pulse of nanosecond duration.

Enlargement and Contracture of C2-Ceramide Channels

PubMed Central

Siskind, Leah J.; Davoody, Amirparviz; Lewin, Naomi; Marshall, Stephanie; Colombini, Marco

2003-01-01

Ceramides are known to play a major regulatory role in apoptosis by inducing cytochrome c release from mitochondria. We have previously reported that ceramide, but not dihydroceramide, forms large and stable channels in phospholipid membranes and outer membranes of isolated mitochondria. C2-ceramide channel formation is characterized by conductance increments ranging from <1 to >200 nS. These conductance increments often represent the enlargement and contracture of channels rather than the opening and closure of independent channels. Enlargement is supported by the observation that many small conductance increments can lead to a large decrement. Also the initial conductances favor cations, but this selectivity drops dramatically with increasing total conductance. La+3 causes rapid ceramide channel disassembly in a manner indicative of large conducting structures. These channels have a propensity to contract by a defined size (often multiples of 4 nS) indicating the formation of cylindrical channels with preferred diameters rather than a continuum of sizes. The results are consistent with ceramides forming barrel-stave channels whose size can change by loss or insertion of multiple ceramide columns. PMID:12944273

Heat and mass transfer within partially wetted packed fractured granular beds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalil, E.B.; Karim, G.A.

1996-10-01

Fractured granular beds heated by hot gaseous streams have been the subject of numerous investigations in recent years due to their importance in many applications such as in in-situ and enhanced oil recovery. In a previous paper (Khalil and Karim, 1995) the results of an investigation of some aspects of the transport processes that occur within dry granular beds were reported. The present contribution examines similar beds when partially wetted. The granular beds were cylindrical in shape containing an axial central small diameter circular channel representing a fracture which can have different permeability from that of the main bed. Itmore » is shown that the mass flow rate of the hot gases, the relative permeability of the bed and the central channel as well as the initial liquid content of the bed control the drying rate. The results of an analytical model formulated to simulate the drying process in unobstructed channel beds showed good agreement with experimental results at low temperatures, however deviations occurred as the drying proceeds at higher temperatures.« less

Construction and experimental validation of a simple, compact, resealable, and reliable Vycor{sup ®} superleak assembly for use at low temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jahromi, Amir E.; Miller, Franklin K.

A new method of constructing a superleak assembly for use in experiments involving {sup 4}He or {sup 3}He-{sup 4}He mixtures at very low temperatures is described. Superleaks are made of a porous medium with very small pores and channels. Superleaks are often incorporated in thermomechanical pumps, superfluid magnetic pumps, dilution refrigerators, and superfluid helium transfer systems. We used several cylindrical pieces of Vycor, a permeable glass with average pore diameter of 40 Å and porosity of 28%, as a candidate to be used in our superleak assembly. Our design is simple and compact. Our superleak assembly can be disassembled andmore » easily reassembled for reuse. We successfully tested and validated this device at temperatures between 1.4 K and 2.7 K. We experienced no superfluid leaks into the surrounding vacuum. We also report that thermal cycling caused no performance degradation. It is our goal to share the design and construction techniques of this new superleak assembly.« less

Decoding structural complexity in conical carbon nanofibers.

PubMed

Zhu, Yi-An; Wang, Zi-Jun; Cheng, Hong-Ye; Yang, Qin-Min; Sui, Zhi-Jun; Zhou, Xing-Gui; Chen, De

2017-06-07

Conical carbon nanofibers (CNFs) exist primarily as graphitic ribbons that fold into a cylindrical structure with the formation of a hollow core. Structural analysis aided by molecular modeling proves useful for obtaining a full picture of how the size of the central channel varies from fiber to fiber. From a geometrical perspective, conical CNFs possibly have cone tips that are nearly closed. On the other hand, their fiber wall thickness can be reduced to a minimum possible value that is determined solely by the apex angle, regardless of the outer diameter. A formula has been developed to express the number of carbon atoms present in conical CNFs in terms of measurable structural parameters. It appears that the energetically preferred fiber wall thickness increases not only with the apex angle, but also with the number of atoms in the constituent graphitic cones. The origin of the empirical observation that conical CNFs with small apex angles tend to have a large hollow core lies in the fact that in graphene sheets that are more highly curved the curvature-induced strain energy rises more rapidly as the fiber wall thickens.

Secondary aspiration of aerosol particles into thin-walled nozzles facing the wind

NASA Astrophysics Data System (ADS)

Lipatov, G. N.; Grinshpun, S. A.; Semenyuk, T. I.; Sutugin, A. G.

Problems of sampling aerosols from the turbulent atmosphere have been studied experimentally. The research was carried out with such particle sizes, type of samplers and sampling conditions that relate to those encountered in practical occupational hygiene and environmental monitoring. Distortion of the aerosol initial concentration was measured in a wind tunnel by a comparison method. Such distortions were caused by the external aspiration from a turbulent down flow using a vertical thin-walled cylindrical sampler. In addition, inertial errors themselves were determined by the limiting trajectory method. The difference between the results obtained with the help of the above methods showed the presence of secondary aspiration after the particles rebound from the outer nozzle surface for anisokinetical sampling. This fact was established by means of a set of special experiments with nozzles of various properties of the outer surface. Values of the rebound coefficient for Lycopodium particles aspirated into copper samplers over a range of diameters of 0.5-1 cm and anisokinetical coefficients (velocity ratio) of 1-40 were obtained. The conditions under which the efficiency of secondary aspiration is small were also defined.

Variation in bed level shear stress on surfaces sheltered by nonerodible roughness elements

NASA Astrophysics Data System (ADS)

Sutton, Stephen L. F.; McKenna-Neuman, Cheryl

2008-09-01

Direct bed level observations of surface shear stress, pressure gradient variability, turbulence intensity, and fluid flow patterns were carried out in the vicinity of cylindrical roughness elements mounted in a boundary layer wind tunnel. Paired corkscrew vortices shed from each of the elements result in elevated shear stress and increased potential for the initiation of particle transport within the far wake. While the size and shape of these trailing vortices change with the element spacing, they persist even for large roughness densities. Wake interference coincides with the impingement of the upwind horseshoe vortices upon one another at a point when their diameter approaches half the distance between the roughness elements. While the erosive capability of the horseshoe vortex has been suggested for a variety of settings, the present study shows that the fluid stress immediately beneath this coherent structure is actually small in comparison to that caused by compression of the incident flow as it is deflected around the element and attached vortex. Observations such as these are required for further refinement of models of stress partitioning on rough surfaces.

A flexible, bolaamphiphilic template for mesoporous silicas.

PubMed

Yuen, Alexander K L; Heinroth, Falk; Ward, Antony J; Masters, Anthony F; Maschmeyer, Thomas

2013-08-28

A novel symmetrical bolaamphiphile, containing two N-methylimidazolium head-groups bridged by a 32-methylene linker, was synthesized and characterized. A variety of mesoporous silicas was prepared using the bolaamphiphile as a "soft template". The effects of absolute surfactant concentration and synthesis conditions upon the morphologies of these silicas were investigated. For a given surfactant concentration, particle morphology; pore size; and pore ordering were modified through control of the template to silica-precursor ratio and synthesis conditions. Observed morphologies included: lenticular core-shell nanoparticles and decorticated globules, truncated hexagonal plates, and sheets. In all cases the mesopores are aligned along the shortest axis of the nanomaterial. Decorticated materials displayed surface areas of up to 1200 m(2) g(-1) and pore diameters (D(BJH)) of 24-28 Å. Small-angle X-ray diffraction and transmission electron microscopy measurements revealed that the majority of the materials has elliptical pores arranged in rectangular lattices (c2mm). Adoption of this symmetry group is a result of the template aggregate deformation from a regular hexagonal phase of cylindrical rods to a ribbon phase under the synthetic conditions.

Potential of an emissive cylindrical probe in plasma.

PubMed

Fruchtman, A; Zoler, D; Makrinich, G

2011-08-01

The floating potential of an emissive cylindrical probe in a plasma is calculated for an arbitrary ratio of Debye length to probe radius and for an arbitrary ion composition. In their motion to the probe the ions are assumed to be collisionless. For a small Debye length, a two-scale analysis for the quasineutral plasma and for the sheath provides analytical expressions for the emitted and collected currents and for the potential as functions of a generalized mass ratio. For a Debye length that is not small, it is demonstrated that, as the Debye length becomes larger, the probe potential approaches the plasma potential and that the ion density near the probe is not smaller but rather is larger than it is in the plasma bulk.

Estimating air-drying times of small-diameter ponderosa pine and Douglas-fir logs

Treesearch

William T. Simpson; Xiping Wang

2004-01-01

One potential use for small-diameter ponderosa pine and Douglas-fir timber is in log form. Many potential uses of logs require some degree of drying. Even though these small diameters may be considered small in the forestry context, their size when compared to typical lumber thickness dimensions is large. These logs, however, may require uneconomically long kiln-drying...

A horizontal inflatable habitat for SEI

NASA Astrophysics Data System (ADS)

Kennedy, Kriss J.

The inflatable habitat described in this paper is a horizontally-oriented cylindrical pneumatic structure. It is part of NASA's ongoing effort to study inflatables as alternative habitats for the Space Exploration Initiative. This inflatable habitat provides a living and working environment for a crew of 12. It is an 8-m diameter by 45.34-m cylinder containing 2145 cu m of volume. Two levels of living and working areas make up the 547 sq m of floor space.

Influence of multiple scattering and absorption on the full scattering profile and the isobaric point in tissue

NASA Astrophysics Data System (ADS)

Duadi, Hamootal; Fixler, Dror

2015-05-01

Light reflectance and transmission from soft tissue has been utilized in noninvasive clinical measurement devices such as the photoplethysmograph (PPG) and reflectance pulse oximeter. Incident light on the skin travels into the underlying layers and is in part reflected back to the surface, in part transferred and in part absorbed. Most methods of near infrared (NIR) spectroscopy focus on the volume reflectance from a semi-infinite sample, while very few measure transmission. We have previously shown that examining the full scattering profile (angular distribution of exiting photons) provides more comprehensive information when measuring from a cylindrical tissue. Furthermore, an isobaric point was found which is not dependent on changes in the reduced scattering coefficient. The angle corresponding to this isobaric point depends on the tissue diameter. We investigated the role of multiple scattering and absorption on the full scattering profile of a cylindrical tissue. First, we define the range in which multiple scattering occurs for different tissue diameters. Next, we examine the role of the absorption coefficient in the attenuation of the full scattering profile. We demonstrate that the absorption linearly influences the intensity at each angle of the full scattering profile and, more importantly, the absorption does not change the position of the isobaric point. The findings of this work demonstrate a realistic model for optical tissue measurements such as NIR spectroscopy, PPG, and pulse oximetery.

Electron beam extraction on plasma cathode electron sources system

NASA Astrophysics Data System (ADS)

Purwadi, Agus; Taufik, M., Lely Susita R.; Suprapto, Saefurrochman, H., Anjar A.; Wibowo, Kurnia; Aziz, Ihwanul; Siswanto, Bambang

2017-03-01

ELECTRON BEAM EXTRACTION ON PLASMA CATHODE ELECTRON SOURCES SYSTEM. The electron beam extraction through window of Plasma Generator Chamber (PGC) for Pulsed Electron Irradiator (PEI) device and simulation of plasma potential has been studied. Plasma electron beam is extracted to acceleration region for enlarging their power by the external accelerating high voltage (Vext) and then it is passed foil window of the PEI for being irradiated to any target (atmospheric pressure). Electron beam extraction from plasma surface must be able to overcome potential barrier at the extraction window region which is shown by estimate simulation (Opera program) based on data of plasma surface potential of 150 V with Ueks values are varied by 150 kV, 175 kV and 200 kV respectively. PGC is made of 304 stainless steel with cylindrical shape in 30 cm of diameter, 90 cm length, electrons extraction window as many as 975 holes on the area of (15 × 65) cm2 with extraction hole cell in 0.3 mm of radius each other, an cylindrical shape IEP chamber is made of 304 stainless steel in 70 cm diameter and 30 cm length. The research result shown that the acquisition of electron beam extraction current depends on plasma parameters (electron density ne, temperature Te), accelerating high voltage Vext, the value of discharge parameter G, anode area Sa, electron extraction window area Se and extraction efficiency value α.

Extrusion of small-diameter, thin-wall tungsten tubing

NASA Technical Reports Server (NTRS)

Blankenship, C. P.; Gyorgak, C. A.

1967-01-01

Small-diameter, thin-wall seamless tubing of tungsten has been fabricated in lengths of up to 10 feet by hot extrusion over a floating mandrel. Extrusion of 0.50-inch-diameter tubing over 0.4-inch-diameter mandrels was accomplished at temperatures ranging from 3000 degrees to 4000 degrees F.

77 FR 59374 - Certain Small Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe (Under 41/2

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-27

... DEPARTMENT OF COMMERCE International Trade Administration [A-588-851] Certain Small Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe (Under 4\\1/2\\ Inches) From Japan: Rescission... antidumping order on certain small diameter carbon and alloy seamless standard, line and pressure pipe (under...

Method for applying pyrolytic carbon coatings to small particles

DOEpatents

Beatty, Ronald L.; Kiplinger, Dale V.; Chilcoat, Bill R.

1977-01-01

A method for coating small diameter, low density particles with pyrolytic carbon is provided by fluidizing a bed of particles wherein at least 50 per cent of the particles have a density and diameter of at least two times the remainder of the particles and thereafter recovering the small diameter and coated particles.

Forest Products Laboratory research program on small-diameter material.

Treesearch

2000-01-01

Forests in the United States contain a significant amount of small-diameter and underutilized material. These overstocked stands not only increase the risk of insect, disease, fire, and drought damage, but also are costly to remove. Finding economical and marketable uses for small-diameter and underutilized material would alleviate these problems while improving...

75 FR 64250 - Small Diameter Graphite Electrodes From the People's Republic of China: Extension of Time Limit...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-19

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-929] Small Diameter Graphite Electrodes From the People's Republic of China: Extension of Time Limit for the Preliminary Results of the... review of the antidumping duty order on small diameter graphite electrodes from the People's Republic of...

Response of Solid He-4 to External Stress: Interdigital Capacitor Solid Level Detector and Optical Interferometer

NASA Technical Reports Server (NTRS)

Fay, J.; Wada, Y.; Masutomi, R.; Elkholy, T.; Kojima, H.

2003-01-01

Two experiments are being conducted to observe the liquid/solid interface of He-4 near 1 K. Interesting instabilities are expected to occur when the solid is non-hydrostatically stressed. (1)A compact interdigital capacitor is used as a level detector to observe solid He-4 to which stresses are applied externally. The capacitor consists of 38 interlaced 50 m wide and 3.8 mm long gold films separated by 50 m and deposited onto a 5 mm by 5 mm sapphire substrate. The capacitor is placed on one flat end wall of a cylindrical chamber (xx mm diameter and xx mm long). The solid is grown to a known height and a stress is applied by a tubular PZT along the cylindrical axis. The observed small change in height of the solid at the wall is linearly proportional to the applied stress. The solid height decreases under compressive stress but does not change under tensile stress. The response of the solid on compressive stress is consistent with the expected quadratic dependence on strain. (2)Interferometric techniques are being developed for observing the solid He-4 surface profile. A laser light source is brought into the low temperature region via single mode optical fiber. The interference pattern is transmitted back out of the low temperature apparatus via optical fiber bundle. The solid He-4 growth chamber will be equipped with two PZT's such that stress can be applied from orthogonal directions. Orthogonally applied stress is expected to induce surface instability with island-like deformation on a grid pattern. Apparatus design and progress of its construction are described.

A study on the imaging characteristics of Gold nanoparticles as a contrast agent in X-ray computed tomography

NASA Astrophysics Data System (ADS)

Mesbahi, Asghar; Famouri, Fatemeh; Ahar, Mohammad Johari; Ghaffari, Maryam Olade; Ghavami, Seyed Mostafa

2017-03-01

Aim: In the current study, some imaging characteristics of AuNPs were quantitatively analyzed and compared with two conventional contrast media (CM) including Iodine and Gadolinium by using of a cylindrical phantom. Methods: AuNPs were synthesized with the mean diameter of 16 nm and were equalized to the concentration of 0.5, 1, 2 and 4 mg/mL in the same volumes. A cylindrical phantom resembling the head and neck was fabricated and drilled to contain small tubes filled with Iodine, Gadolinium, and AuNPs as contrast media. The phantom was scanned in different exposure techniques and CT numbers of three studied contrast media inside test tubes were measured in terms of Hounsfield Unit (HU). The imaging parameters of the noise and contrast to noise ratios (CNR) were calculated for all studied CMs. Results: AuNPs showed 128% and 166% higher CT number in comparison with Iodine and Gadolinium respectively. Also, Iodine had a greater CT number than Gadolinium for the same exposure techniques and concentration. The maximum CT number for AuNPs and studied contrast materials was obtained at the highest mAs and the lowest tube potential. The maximum CT number were 1033±11 (HU) for AuNP, 565±10 (HU) for Iodine, 458±11 for Gadolinium. Moreover, the maximum CNRs of 433±117, 203±53, 145±37 were found for AuNPs, Iodine and Gadolinium respectively. Conclusion: The contrast agent based on AuNPs showed higher imaging quality in terms of contrast and noise relative to other iodine and gadolinium based contrast media in X-ray computed tomography. Application of the AuNPs as a contrast medium in x-ray CT is recommended.

Lumber volume and value recovery from small-diameter black cherry, sugar maple, and red oak logs

Treesearch

Jan Wiedenbeck; Matthew Scholl; Paul Blankenhorn; Chuck Ray

2017-01-01

While only a very small percentage of hardwood logs sawn by conventional sawmills in the U.S. have small-end diameters less than 10 in, portable and scragg mills often saw smaller logs. With the closure of regionally important oriented strand board and pulpwood operations, small-diameter logs are considered to have no value in some markets. This study was...

Electrospun meshes possessing region-wise differences in fiber orientation, diameter, chemistry and mechanical properties for engineering bone-ligament-bone tissues.

PubMed

Samavedi, Satyavrata; Vaidya, Prasad; Gaddam, Prudhvidhar; Whittington, Abby R; Goldstein, Aaron S

2014-12-01

Although bone-patellar tendon-bone (B-PT-B) autografts are the gold standard for repair of anterior cruciate ligament ruptures, they suffer from drawbacks such as donor site morbidity and limited supply. Engineered tissues modeled after B-PT-B autografts are promising alternatives because they have the potential to regenerate connective tissue and facilitate osseointegration. Towards the long-term goal of regenerating ligaments and their bony insertions, the objective of this study was to construct 2D meshes and 3D cylindrical composite scaffolds - possessing simultaneous region-wise differences in fiber orientation, diameter, chemistry and mechanical properties - by electrospinning two different polymers from off-set spinnerets. Using a dual drum collector, 2D meshes consisting of an aligned polycaprolactone (PCL) fiber region, randomly oriented poly(lactide-co-glycolide) (PLGA) fiber region and a transition region (comprised of both PCL and PLGA fibers) were prepared, and region-wise differences were confirmed by microscopy and tensile testing. Bone marrow stromal cells (BMSCs) cultured on these meshes exhibited random orientations and low aspect ratios on the random PLGA regions, and high aspect ratios and alignment on the aligned PCL regions. Next, meshes containing an aligned PCL region flanked by two transition regions and two randomly oriented PLGA regions were prepared and processed into 3D cylindrical composite scaffolds using an interpenetrating photo-crosslinkable polyethylene glycol diacrylate hydrogel to recapitulate the shape of B-PT-B autografts. Tensile testing indicated that cylindrical composites were mechanically robust, and eventually failed due to stress concentration in the aligned PCL region. In summary, this study demonstrates a process to fabricate electrospun meshes possessing region-wise differences in properties that can elicit region-dependent cell responses, and be readily processed into scaffolds with the shape of B-PT-B autografts. © 2014 Wiley Periodicals, Inc.

Intra-aortic balloon shape change: effects on volume displacement during inflation and deflation.

PubMed

Khir, Ashraf William; Bruti, Gianpaolo

2013-07-01

It has been observed that operating the intra-aortic balloon at an angle to the horizontal resulted in a reduction of the volume displaced toward the coronary arteries and compromised afterload reduction. Therefore, the aim of this work is to examine whether changing the current balloon shape, which has not been altered for 40 years, could compensate for the negative hemodynamic effects due to angulation. We tested two tapered balloons, increasing diameter (TID) and decreasing diameter (TDD), and compared the results with those obtained from a standard cylindrical balloon. The balloons were tested in vitro at 60 beats/min and a static pressure of 90 mm Hg. The balloons were operated at four angles (0°, 20°, 30°, 45°), and the pressure at three locations along the balloon (base, middle, and tip) was also measured. Flow rate upstream of the tip of the balloon was also measured to indicate the flow displaced toward the coronary circulation. The relative volume displaced toward (VUTVi) and suctioned away from (VUTVd) the simulated ascending aorta, during inflation and deflation, respectively, is reduced when a standard cylindrical balloon is operated at an angle to the horizontal. The TDD provided the greatest VUTVi and also produced the largest pulse pressure during deflation. Although the TID provided less VUTVi and VUTVd at smaller angles, it was not markedly affected by the change of angle. According to these results, different balloon shapes analyzed, with comparable volume to that of a cylindrical balloon, produced greater inflation and deflation benefits, at the horizontal and at a range of angles to the horizontal. Further investigations are required to optimize the shape of the tapered balloons to fit into the available physiological space. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

Influence of Structural Parameters on the Performance of Vortex Valve Variable-Thrust Solid Rocket Motor

NASA Astrophysics Data System (ADS)

Wei, Xianggeng; Li, Jiang; He, Guoqiang

2017-04-01

The vortex valve solid variable thrust motor is a new solid motor which can achieve Vehicle system trajectory optimization and motor energy management. Numerical calculation was performed to investigate the influence of vortex chamber diameter, vortex chamber shape, and vortex chamber height of the vortex valve solid variable thrust motor on modulation performance. The test results verified that the calculation results are consistent with laboratory results with a maximum error of 9.5%. The research drew the following major conclusions: the optimal modulation performance was achieved in a cylindrical vortex chamber, increasing the vortex chamber diameter improved the modulation performance of the vortex valve solid variable thrust motor, optimal modulation performance could be achieved when the height of the vortex chamber is half of the vortex chamber outlet diameter, and the hot gas control flow could result in an enhancement of modulation performance. The results can provide the basis for establishing the design method of the vortex valve solid variable thrust motor.

Fabrication of Two-Dimensional Arrays of Diameter-Tunable PS-b-P2VP Nanowires at the Air/Water Interface.

PubMed

Zhao, Xingjuan; Yu, Xiaoli; Lee, Yong-Ill; Liu, Hong-Guo

2016-11-15

Composite thin films with well-defined and parallel nanowires were fabricated from the binary blends of a diblock copolymer polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) and several homopolystyrenes (h-PSs) at the air/liquid interface through a facile technique, which involves solution self-assembly, interface adsorption, and further self-organization processes. It was confirmed that the nanowires that appeared at the air/water interface came from the cylindrical micelles formed in solution. Interestingly, the diameters of the nanowires are uniform and can be tuned precisely from 45 to 247 nm by incorporating the h-PS molecules into the micellar core. This parallel alignment of the nanowires has potential applications in optical devices and enables the nanowires to be used as templates to prepare functional nanostructures. The extent to which h-PS molecules with different molecular weights are able to influence the diameter control of the nanowires was also systematically investigated.

Estimating surface hardening profile of blank for obtaining high drawing ratio in deep drawing process using FE analysis

NASA Astrophysics Data System (ADS)

Tan, C. J.; Aslian, A.; Honarvar, B.; Puborlaksono, J.; Yau, Y. H.; Chong, W. T.

2015-12-01

We constructed an FE axisymmetric model to simulate the effect of partially hardened blanks on increasing the limiting drawing ratio (LDR) of cylindrical cups. We partitioned an arc-shaped hard layer into the cross section of a DP590 blank. We assumed the mechanical property of the layer is equivalent to either DP980 or DP780. We verified the accuracy of the model by comparing the calculated LDR for DP590 with the one reported in the literature. The LDR for the partially hardened blank increased from 2.11 to 2.50 with a 1 mm depth of DP980 ring-shaped hard layer on the top surface of the blank. The position of the layer changed with drawing ratios. We proposed equations for estimating the inner and outer diameters of the layer, and tested its accuracy in the simulation. Although the outer diameters fitted in well with the estimated line, the inner diameters are slightly less than the estimated ones.

Production and cost of harvesting, processing, and transporting small-diameter (< 5 inches) trees for energy

Treesearch

Fei Pan; Han-Sup Han; Leonard R. Johnson; William J. Elliot

2008-01-01

Dense, small-diameter stands generally require thinning from below to improve fire-tolerance. The resulting forest biomass can be used for energy production. The cost of harvesting, processing, and transporting small-diameter trees often exceeds revenues due to high costs associated with harvesting and transportation and low market values for forest biomass....

Options for small-diameter hardwood utilization: past and present

Treesearch

Matthew S. Bumgardner; Bruce G. Hansen; Albert T. Schuler; Philip A. Araman

2000-01-01

Effective and maximum value use of small-diameter hardwood timber has long been of interest to forest managers and researchers. In addition to being a significant component of the standing forest base, small-diameter hardwoods often are available after thinning or other tending operations. Although the use of this material is important to achieving healthy and...

Evaluation of roll-off trailers in small-diameter applications

Treesearch

Bob Rummer; John Klepac

2003-01-01

Concern about wildfire in overstocked forests of the western U.S. has led to increased emphasis on extraction of small-diameter material. Removing this material improves forest health, reduces fuel loading, and may generate value that can be used to offset the costs of operation. However, the cost of small-diameter operations (both in-woods and secondary processing)...

Small-diameter success stories II

Treesearch

Jean Livingston

2006-01-01

Many of our national forests are in critical need of restoration. These forests are dense, with an abundance of small-diameter, tightly spaced trees and underbrush that can contribute to the rapid growth of fire. If economic and value-added uses for this small-diameter and unmerchantable material can be found, forest restoration costs could be offset and catastrophic...

Options for Small-Diameter Hardwood Utilization: Past and Present

Treesearch

Matthew S. Bumgardner; Bruce G. Hansen; Albert T. Schuler; Philip A. Araman; Philip A. Araman

2001-01-01

Effective and maximum value use of small-diameter hardwood timber has long been of interest to forest managers and researchers. In addition to being a significant component of the standing forest base, small-diameter hardwoods often are available after thinning or other tending operations. Although the use of this material is important to achieving healthy and...

Ion-Acoustic Wave-Particle Energy Flow Rates

NASA Astrophysics Data System (ADS)

Berumen, Jorge; Chu, Feng; Hood, Ryan; Mattingly, Sean; Skiff, Fred

2017-10-01

We present an experimental characterization of the energy flow rates for ion acoustic waves. The experiment is performed in a cylindrical, magnetized, singly-ionized Argon, inductively-coupled gas discharge plasma that is weakly collisional with typical conditions: n 109cm-3 Te 9 eV and B 660 kG. A 4 ring antenna with diameter similar to the plasma diameter is used for launching the waves. A survey of the zeroth and first order ion velocity distribution functions (IVDF) is done using Laser-Induced Fluorescence (LIF) as the main diagnostics method. Using these IVDFs along with Vlasov's equation the different energy rates are measured for different values of ion velocity and separation from the antenna. We would like to acknowledge DOE DE-FG02-99ER54543 for their financial support throughout this research.

Microlens frames for laser diode arrays

DOEpatents

Skidmore, J.A.; Freitas, B.L.

1999-07-13

Monolithic microlens frames enable the fabrication of monolithic laser diode arrays and are manufactured inexpensively with high registration, and with inherent focal length compensation for any lens diameter variation. A monolithic substrate is used to fabricate a low-cost microlens array. The substrate is wet-etched or sawed with a series of v-grooves. The v-grooves can be created by wet-etching, by exploiting the large etch-rate selectivity of different crystal planes. The v-grooves provide a support frame for either cylindrical or custom-shaped microlenses. Because the microlens frames are formed by photolithographic semiconductor batch-processing techniques, they can be formed inexpensively over large areas with precise lateral and vertical registration. The v-groove has an important advantage for preserving the correct focus for lenses of varying diameter. 12 figs.

Microlens frames for laser diode arrays

DOEpatents

Skidmore, Jay A.; Freitas, Barry L.

1999-01-01

Monolithic microlens frames enable the fabrication of monolithic laser diode arrays and are manufactured inexpensively with high registration, and with inherent focal length compensation for any lens diameter variation. A monolithic substrate is used to fabricate a low-cost microlens array. The substrate is wet-etched or sawed with a series of v-grooves. The v-grooves can be created by wet-etching, by exploiting the large etch-rate selectivity of different crystal planes. The v-grooves provide a support frame for either cylindrical or custom-shaped microlenses. Because the microlens frames are formed by photolithographic semiconductor batch-processing techniques, they can be formed inexpensively over large areas with precise lateral and vertical registration. The v-groove has an important advantage for preserving the correct focus for lenses of varying diameter.

Single-molecule tracking studies of flow-induced microdomain alignment in cylinder-forming polystyrene-poly(ethylene oxide) diblock copolymer films.

PubMed

Tran-Ba, Khanh-Hoa; Higgins, Daniel A; Ito, Takashi

2014-09-25

Flow-based approaches are promising routes to preparation of aligned block copolymer microdomains within confined spaces. An in-depth characterization of such nanoscale morphologies within macroscopically nonuniform materials under ambient conditions is, however, often challenging. In this study, single-molecule tracking (SMT) methods were employed to probe the flow-induced alignment of cylindrical microdomains (ca. 22 nm in diameter) in polystyrene-poly(ethylene oxide) diblock copolymer (PS-b-PEO) films. Films of micrometer-scale thicknesses were prepared by overlaying a benzene solution droplet on a glass coverslip with a rectangular glass plate, followed by solvent evaporation under a nitrogen atmosphere. The microdomain alignment was quantitatively assessed from SMT data exhibiting the diffusional motions of individual sulforhodamine B fluorescent probes that preferentially partitioned into cylindrical PEO microdomains. Better overall microdomain orientation along the flow direction was observed near the substrate interface in films prepared at a higher flow rate, suggesting that the microdomain alignment was primarily induced by shear flow. The SMT data also revealed the presence of micrometer-scale grains consisting of highly ordered microdomains with coherent orientation. The results of this study provide insights into shear-based preparation of aligned cylindrical microdomains in block copolymer films from solutions within confined spaces.

Ion distributions, exclusion coefficients, and separation factors of electrolytes in a charged cylindrical nanopore: a partially perturbative density functional theory study.

PubMed

Peng, Bo; Yu, Yang-Xin

2009-10-07

The structural and thermodynamic properties for charge symmetric and asymmetric electrolytes as well as mixed electrolyte system inside a charged cylindrical nanopore are investigated using a partially perturbative density functional theory. The electrolytes are treated in the restricted primitive model and the internal surface of the cylindrical nanopore is considered to have a uniform charge density. The proposed theory is directly applicable to the arbitrary mixed electrolyte solution containing ions with the equal diameter and different valences. Large amount of simulation data for ion density distributions, separation factors, and exclusion coefficients are used to determine the range of validity of the partially perturbative density functional theory for monovalent and multivalent counterion systems. The proposed theory is found to be in good agreement with the simulations for both mono- and multivalent counterion systems. In contrast, the classical Poisson-Boltzmann equation only provides reasonable descriptions of monovalent counterion system at low bulk density, and is qualitatively and quantitatively wrong in the prediction for the multivalent counterion systems due to its neglect of the strong interionic correlations in these systems. The proposed density functional theory has also been applied to an electrolyte absorbed into a pore that is a model of the filter of a physiological calcium channel.

Assembling, cleaning, and testing a unique prototype open-ended cylindrical penning trap

NASA Astrophysics Data System (ADS)

Marble, Kassie; Shidling, Praveen; Melconian, Dan

2016-09-01

A new experimental beamline containing a prototype cylindrical penning trap has recently been constructed at the Cyclotron Laboratory at Texas A&M University. The new beamline will enable precision experiments that enhance our understanding of the limits on non-SM processes in the weak interaction through the measurement of the β- ν correlation parameter for T = 2 ,0+ ->0+ supper allowed β-delayed proton emitters. The prototype TAMU TRAP consists of an open-ended cylindrical penning trap of diameter of 90 mm with gold-plated electrodes of oxygen free high conductivity copper to prevent oxidation. The trap's electric quadrupole field is provided by a SHIP TRAPS RF electronic circuit to the four segmented electrodes at the center of the trap while the trap's 7 Tesla radial magnetic field is provided by an Agilent 210 ASR magnet. A discussion of the assembly of the prototype TAMU TRAP, construction of the RF electronic circuit, the experimental set up and alignment of the beamline will be presented. The method used to test the prototype penning trap using an ion source, Faraday cups, and Micro Chanel Plate (MCP) detectors will also be discussed. Work supported by the U.S. Department of Energy under Grant No. DE-FG02-11ER41747 and the National Science Foundation.

Blunt Body Near-Wake Flow Field at Mach 10

NASA Technical Reports Server (NTRS)

Horvath, Thomas; Hannemann, Klaus

1997-01-01

Tests were conducted in a Mach 10 air flow to examine the reattachment process of a free shear layer associated with the near wake of a 70 deg half angle, spherically blunted cone having a cylindrical after body. The nominal free-stream Reynolds number based on model diameter ranged from 0.25 x l0(exp 6) to 1 x l0(exp 6) and the angle of incidence set at 0 and +/- 20 deg. The present study was designed to complement previously reported Mach 6 perfect air tests as well as results obtained in several hypervelocity facilities capable of producing real gas effects. Surface heating rates were inferred from temperature time histories from coaxial surface thermocouples on the model forebody and thin film resistance gages along the model base and cylindrical after body. Limited forebody, base, and support sting surface pressures were obtained with piezoresistive Experimental results are compared to laminar perfect gas predictions provided by a 3-0 Navier Stokes code (NSHYP). Shear layer impingement on the instrumented cylindrical after body resulted in a localized heating maximum that was 16 to 18percent of the forebody stagnation point and a factor of 2 higher than laminar predictions, suggesting a transitional or turbulent shear layer. transducers.

A study on the effect of tool electrode thickness on MRR, and TWR in electrical discharge turning process

NASA Astrophysics Data System (ADS)

Gohil, Vikas; Puri, YM

2018-04-01

Turning by electrical discharge machining (EDM) is an emerging area of research. Generally, wire-EDM is used in EDM turning because it is not concerned with electrode tooling cost. In EDM turning wire electrode leaves cusps on the machined surface because of its small diameters and wire breakage which greatly affect the surface finish of the machined part. Moreover, one of the limitations of the process is low machining speed as compared to constituent processes. In this study, conventional EDM was employed for turning purpose in order to generate free-form cylindrical geometries on difficult-to-cut materials. Therefore, a specially designed turning spindle was mounted on a conventional die-sinking EDM machine to rotate the work piece. A conductive preshaped strip of copper as a forming tool is fed (reciprocate) continuously against the rotating work piece; thus, a mirror image of the tool is formed on the circumference of the work piece. In this way, an axisymmetric work piece can be made with small tools. The developed process is termed as the electrical discharge turning (EDT). In the experiments, the effect of machining parameters, such as pulse-on time, peak current, gap voltage and tool thickness on the MRR, and TWR were investigated and practical machining was carried out by turning of SS-304 stainless steel work piece.

Method for measurement of radon diffusion and solubility in solid materials

NASA Astrophysics Data System (ADS)

Maier, Andreas; Weber, Uli; Dickmann, Jannis; Breckow, Joachim; van Beek, Patrick; Schardt, Dieter; Kraft, Gerhard; Fournier, Claudia

2018-02-01

In order to study the permeation i.e. the diffusion and solubility of radon gas in biological material, a new setup was constructed and a novel analysis was applied to obtain diffusion and solubility coefficients. Thin slabs of solid materials were installed between detector housing and the surrounding radon exposure chamber of 50 Ls volume. In this setup radon can diffuse through thin test samples into a cylindrical volume of 5 mm height and 20 mm diameter and reach an α-particle detector. There the 5.49 MeV α-decay of the penetrating radon atoms is measured by a silicon surface barrier detector. The time dependent activities inside the small detector volume are recorded after injection of a known radon activity concentration into the outer chamber. Analyzing the time behavior of the integral α-activity from radon in the small vessel, both, the diffusion coefficient and solubility of the test material can be determined, based on a new mathematical model of the diffusion process concerning the special boundary conditions given by the experimental setup. These first measurements were intended as proof of concept for the detection system and the data analysis. Thin polyethylene foils (LDPE) were selected as material for the diffusion measurements and the results were in agreement with data from literature. In further measurements, we will concentrate on biological material like bone, fat and other tissues.

Shiitake mushroom production on small diameter oak logs in Ohio

Treesearch

S.M. Bratkovich

1991-01-01

Yields of different strains of shiitake mushrooms (Lentinus edodes) were evaluated when produced on small diameter oak logs in Ohio. Logs averaging between 3-4 inches in diameter were inoculated with four spawn strains in 1985.

Sulfur in the Corrosion of Superalloys.

DTIC Science & Technology

1981-11-06

mechanically on SiC paper from 240 grit to 600 grit. Some samples were pre- annealed in one atmosphere of hydrogen at about 8000 C prior to the experiment...experiments the samples were used as-received while in others the samples were given a high temperature anneal prior to the diffusion anneal . The...C04- 74-G-0130. Cylindrical pellets, about 11 mm in diameter by 1.7 mm thick were used as received or pre- annealed in 1 atm 02. The samples were

Superconducting Electronic Film Structures

DTIC Science & Technology

1991-02-14

diameter YBCO films are being tested as the endplates in a cylindrical dielectric resonator. The Q and phase noise of the 15 dielectric resonator will...vortex state. Magnus force ne(v, -VL)x O/C is balanced by a drag force an- Josephson 9 demonstrated that the motion of flux vor- tiparallel to the...age of the same sign as in the normal metal [Fig. 3(b)i. the Magnus force Thus a reversal of the sign of the Hall voltage upon enter- "Se ing the mixed

Implementation of Unsteady Double-Axis of Rotation Motion to Predict Pitch-Damping Moment

DTIC Science & Technology

2016-10-18

2014;51(5). 4. Dupuis A. Aeroballistic range and wind tunnel tests of the basic finner reference projectile from subsonic to high supersonic velocities... modelled . Typically, when computing aerodynamic coefficients, motion about each axis is considered individually (i.e., spin around body-axis, pitch about...has a diameter, , of 0.03 m (1 caliber) and consists of a 10° half- angle cone that is 2.84-calibers long, followed by a 7.16-caliber cylindrical

Gamma-Radiation-Induced Degradation of Actively Pumped Single-Mode Ytterbium-Doped Optical Laser - Postprint

DTIC Science & Technology

2015-01-01

evaluated using the cobalt (Co)-60 gamma irradiation facility at The Ohio State University. A radiation dose rate of 43 krad(Si)/hr was used to expose the...Table 1. Description of the optical fibers used for in-situ analysis of the radiation damage Optical fiber Core Dopant Core/cladding diameters (μm...University is a pool-type gamma irradiation facility using a common cobalt cylindrical rod irradiator submerged 20 feet into a water tank. A

Atomic oxygen effects on metals

NASA Technical Reports Server (NTRS)

Fromhold, Albert T.

1987-01-01

The effect of specimen geometry on the attack of metals by atomic oxygen is addressed. This is done by extending the coupled-currents approach in metal oxidation to spherical and cylindrical geometries. Kinetic laws are derived for the rates of oxidation of samples having these geometries. It is found that the burn-up time for spherical particles of a given diameter can be as much as a factor of 3 shorter than the time required to completely oxidize a planar sample of the same thickness.

Radial force distribution changes associated with tangential force production in cylindrical grasping, and the importance of anatomical registration.

PubMed

Pataky, Todd C; Slota, Gregory P; Latash, Mark L; Zatsiorsky, Vladimir M

2012-01-10

Radial force (F(r)) distributions describe grip force coordination about a cylindrical object. Recent studies have employed only explicit F(r) tasks, and have not normalized for anatomical variance when considering F(r) distributions. The goals of the present study were (i) to explore F(r) during tangential force production tasks, and (ii) to examine the extent to which anatomical registration (i.e. spatial normalization of anatomically analogous structures) could improve signal detectability in F(r) data. Twelve subjects grasped a vertically oriented cylindrical handle (diameter=6 cm) and matched target upward tangential forces of 10, 20, and 30 N. F(r) data were measured using a flexible pressure mat with an angular resolution of 4.8°, and were registered using piecewise-linear interpolation between five manually identified points-of-interest. Results indicate that F(r) was primarily limited to three contact regions: the distal thumb, the distal fingers, and the fingers' metatacarpal heads, and that, while increases in tangential force caused significant increases in F(r) for these regions, they did not significantly affect the F(r) distribution across the hand. Registration was found to substantially reduce between-subject variability, as indicated by both accentuated F(r) trends, and amplification of the test statistic. These results imply that, while subjects focus F(r) primarily on three anatomical regions during cylindrical grasp, inter-subject anatomical differences introduce a variability that, if not corrected for via registration, may compromise one's ability to draw anatomically relevant conclusions from grasping force data. Copyright © 2011 Elsevier Ltd. All rights reserved.

Economic feasibility of products from inland West small-diameter timber

Treesearch

Spelter Henry; Rong Wang; Peter Ince

1996-01-01

A large part of the forests located in the Rocky Mountain region of the U.S. West (inland West) is characterized by densely packed, small-diameter stands. The purpose of this study was to examine the economic feasibility of using small-diameter material from this resource to manufacture various wood products: oriented strandboard (OSB), stud lumber, random-length...

78 FR 62597 - 36(b)(1) Arms Sales Notification

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-22

... Block II missiles, 1000 GBU-39/B Small Diameter Bomb (SDB) with BRU-61 carriage systems, 40 CATM-84H... missiles, 1000 GBU-39/B Small Diameter Bombs (SDB), 40 CATM-84H Captive Air Training Missiles (CATM), 20... Small Diameter Bomb (SDB) I weapon is a 250-lb class, all-up round (AUR) that provides greater than 50nm...

78 FR 62594 - 36(b)(1) Arms Sales Notification

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-22

... Consideration for Purchase: 5000 GBU-39/B Small Diameter Bombs (SDB) with BRU-61 carriage systems, 8 SDB Guided... Emirates has requested a possible sale of 5000 GBU-39/B Small Diameter Bombs (SDB) with BRU-61 carriage... environmental conditions. 5. The GBU-39/B Small Diameter Bomb (SDB) I weapon is a 250-lb class, all-up round...

Suitability of live and fire-killed small-diameter ponderosa and lodgepole pine trees for manufacturing a new structural wood composite

Treesearch

J.M. Linton; H.M. Barnes; R.D. Seale; P.D. Jones; E. Lowell; S.S. Hummel

2010-01-01

Finding alternative uses for raw material from small-diameter trees is a critical problem throughout the United States. In western states, a lack of markets for small-diameter ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta ) can contribute to problems associated with overstocking. To test the feasibility of...

SU-F-207-05: Excess Heat Corrections in a Prototype Calorimeter for Direct Realization of CT Absorbed Dose to Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen-Mayer, H; Tosh, R

2015-06-15

Purpose: To reconcile air kerma and calorimetry measurements in a prototype calorimeter for obtaining absorbed dose in diagnostic CT beams. While corrections for thermal artifacts are routine and generally small in calorimetry of radiotherapy beams, large differences in relative stopping powers of calorimeter materials at the lower energies typical of CT beams greatly magnify their effects. Work-to-date on the problem attempts to reconcile laboratory measurements with modeling output from Monte Carlo and finite-element analysis of heat transfer. Methods: Small thermistor beads were embedded in a polystyrene (PS) core element of 1 cm diameter, which was inserted into a cylindrical HDPEmore » phantom of 30 cm diameter and subjected to radiation in a diagnostic CT x-ray imaging system. Resistance changes in the thermistors due to radiation heating were monitored via lock-in amplifier. Multiple 3-second exposures were recorded at 8 different dose-rates from the CT system, and least-squares fits to experimental data were compared to an expected thermal response obtained by finite-element analysis incorporating source terms based on semi-empirical modeling and Monte Carlo simulation. Results: Experimental waveforms exhibited large thermal artifacts with fast time constants, associated with excess heat in wires and glass, and smaller steps attributable to radiation heating of the core material. Preliminary finite-element analysis follows the transient component of the signal qualitatively, but predicts a slower decay of temperature spikes. This was supplemented by non-linear least-squares fits incorporating semi-empirical formulae for heat transfer, which were used to obtain dose-to-PS in reasonable agreement with the output of Monte Carlo calculations that converts air kerma to absorbed dose. Conclusion: Discrepancies between the finite-element analysis and our experimental data testify to the very significant heat transfer correction required for absorbed dose calorimetry of diagnostic CT beams. The results obtained here are being used to refine both simulations and design of calorimeter core components.« less

On-machine precision preparation and dressing of ball-headed diamond wheel for the grinding of fused silica

NASA Astrophysics Data System (ADS)

Chen, Mingjun; Li, Ziang; Yu, Bo; Peng, Hui; Fang, Zhen

2013-09-01

In the grinding of high quality fused silica parts with complex surface or structure using ball-headed metal bonded diamond wheel with small diameter, the existing dressing methods are not suitable to dress the ball-headed diamond wheel precisely due to that they are either on-line in process dressing which may causes collision problem or without consideration for the effects of the tool setting error and electrode wear. An on-machine precision preparation and dressing method is proposed for ball-headed diamond wheel based on electrical discharge machining. By using this method the cylindrical diamond wheel with small diameter is manufactured to hemispherical-headed form. The obtained ball-headed diamond wheel is dressed after several grinding passes to recover geometrical accuracy and sharpness which is lost due to the wheel wear. A tool setting method based on high precision optical system is presented to reduce the wheel center setting error and dimension error. The effect of electrode tool wear is investigated by electrical dressing experiments, and the electrode tool wear compensation model is established based on the experimental results which show that the value of wear ratio coefficient K' tends to be constant with the increasing of the feed length of electrode and the mean value of K' is 0.156. Grinding experiments of fused silica are carried out on a test bench to evaluate the performance of the preparation and dressing method. The experimental results show that the surface roughness of the finished workpiece is 0.03 μm. The effect of the grinding parameter and dressing frequency on the surface roughness is investigated based on the measurement results of the surface roughness. This research provides an on-machine preparation and dressing method for ball-headed metal bonded diamond wheel used in the grinding of fused silica, which provides a solution to the tool setting method and the effect of electrode tool wear.

74. View of small steam tank used in 'blowing down' ...

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

74. View of small steam tank used in 'blowing down' or cleaning boilers; in background can be seen the bottom of cylindrical water tank located in setback at southeast corner of blowing engine house. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

On the resonance amplification of magnetic perturbations near the threshold of tearing instability in a tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arsenin, V. V., E-mail: arsenin-vv@nrcki.ru; Skovoroda, A. A., E-mail: skovoroda-aa@nrcki.ru

2015-12-15

Using a cylindrical model, a relatively simple description is presented of how a magnetic field perturbation stimulated by a low external helical current or a small helical distortion of the boundary and generating magnetic islands penetrates into a plasma column with a magnetic surface q=m/n to which tearing instability is attached. Linear analysis of the classical instability with an aperiodic growth of the perturbation in time shows that the perturbation amplitude in plasma increases in a resonant manner as the discharge parameters approach the threshold of tearing instability. In a stationary case, under the assumption on the helical character ofmore » equilibrium, which can be found from the two-dimensional nonlinear equation for the helical flux, there is no requirement for the small size of the island. Examples of calculations in which magnetic islands are large near the threshold of tearing instability are presented. The bifurcation of equilibrium near the threshold of tearing instability in plasma with a cylindrical boundary, i.e., the existence of helical equilibrium (along with cylindrical equilibrium) with large islands, is described. Moreover, helical equilibrium can also exist in the absence of instability.« less

Highly organised and dense vertical silicon nanowire arrays grown in porous alumina template on <100> silicon wafers

PubMed Central

2013-01-01

In this work, nanoimprint lithography combined with standard anodization etching is used to make perfectly organised triangular arrays of vertical cylindrical alumina nanopores onto standard <100>−oriented silicon wafers. Both the pore diameter and the period of alumina porous array are well controlled and can be tuned: the periods vary from 80 to 460 nm, and the diameters vary from 15 nm to any required diameter. These porous thin layers are then successfully used as templates for the guided epitaxial growth of organised mono-crystalline silicon nanowire arrays in a chemical vapour deposition chamber. We report the densities of silicon nanowires up to 9 × 109 cm−2 organised in highly regular arrays with excellent diameter distribution. All process steps are demonstrated on surfaces up to 2 × 2 cm2. Specific emphasis was made to select techniques compatible with microelectronic fabrication standards, adaptable to large surface samples and with a reasonable cost. Achievements made in the quality of the porous alumina array, therefore on the silicon nanowire array, widen the number of potential applications for this technology, such as optical detectors or biological sensors. PMID:23773702

Angular and radial dependence of the energy response factor for LIF-TLD micro-rods in 125L permanent implant source.

PubMed

Mobit, Paul; Badragan, Iulian

2006-01-01

EGSnrc Monte Carlo simulations were used to calculate the angular and radial dependence of the energy response factor for LiF-thermoluminescence dosemeters (TLDs) irradiated with a commercially available (125)I permanent brachytherapy source. The LiF-TLDs were modelled as cylindrical micro-rods of length 6 mm and with diameters of 1 mm and 5 mm. The results show that for a LiF-TLD micro-rod of 1 mm diameter, the energy response relative to (60)Co gamma rays is 1.406 +/- 0.3% for a polar angle of 90 degrees and radial distance of 1.0 cm. When the diameter of the micro-rod is increased from 1 to 5 mm, the energy response decreases to 1.32 +/- 0.3% at the same point. The variation with position of the energy response factor is not >5% in a 6 cm x 6 cm x 6 cm calculation grid for the 5 mm diameter micro-rod. The results show that there is a change in the photon spectrum with angle and radial distance, which causes the variation of the energy response.

Stress-strain relationship of PDMS micropillar for force measurement application

NASA Astrophysics Data System (ADS)

Johari, Shazlina; Shyan, L. Y.

2017-11-01

There is an increasing interest to use polydimethylsiloxane (PDMS) based materials as bio-transducers for force measurements in the order of micro to nano Newton. The accuracy of these devices relies on appropriate material characterization of PDMS and modelling to convert the micropillar deformations into the corresponding forces. Previously, we have reported on fabricated PDMS micropillar that acts as a cylindrical cantilever and was experimentally used to measure the force of the nematode C. elegans. In this research, similar PDMS micropillars are designed and simulated using ANSYS software. The simulation involves investigating two main factors that is expected to affect the force measurement performance; pillar height and diameter. Results show that the deformation increases when pillar height is increased and the deformation is inversely proportional to the pillar diameter. The maximum deformation obtained is 713 um with pillar diameter of 20 um and pillar height of 100 um. Results of stress and strain show similar pattern, where their values decreases as pillar diameter and height is increased. The simulated results are also compared with the calculated displacement. The trend for both calculated and simulated values are similar with 13% average difference.

Application of small-diameter FBG sensors for detection of damages in composites

NASA Astrophysics Data System (ADS)

Okabe, Yoji; Mizutani, Tadahito; Yashiro, Shigeki; Takeda, Nobuo

2001-08-01

Small-diameter fiber Bragg grating (FBG) sensors have been developed by Hitachi Cable Ltd. and the authors. Since the outside diameter of polyimide coating is 52 micrometers , embedding of the sensors into carbon fiber reinforced plastic (CFRP) composites prepregs of 125 micrometers in thickness does not deteriorate the mechanical properties of the composite laminates. In this research, the small-diameter FBG sensor was applied for the detection of transverse cracks in CFRP composites. The FBG sensor was embedded in 0 degree(s) ply of a CFRP cross-ply laminate.

Analyzing the feasibility of utilizing small diameter hardwood timber for solid wood products and residues

Treesearch

Brian Perkins; Bob Smith; Philip Araman

2008-01-01

The eastern hardwood forest contains small diameter timber that is often of lower quality and lower value than larger sawtimber. This small diameter hardwood timber has traditionally been utilized for pulpwood, but it can also be used for lumber and residue production. In order to increase the utilization of this resource by sawmills, a number of analyses need to be...

Elastoplastic State of an Elliptical Cylindrical Shell with a Circular Hole

NASA Astrophysics Data System (ADS)

Storozhuk, E. A.; Chernyshenko, I. S.; Pigol', O. V.

2017-11-01

Static problems for an elastoplastic elliptical cylindrical shell with a circular hole are formulated and a numerical method for solving it is developed. The basic equations are derived using the Kirchhoff-Love theory of deep shells and the theory of small elastoplastic strains. The method employs the method of additional stresses and the finite-element method. The influence of plastic strains and geometrical parameters of the shell subject to internal pressure on the distributions of stresses, strains, and displacements in the zone of their concentration is studied.

Biomechanics and load resistance of small-diameter and mini dental implants: a review of literature.

PubMed

Hasan, Istabrak; Bourauel, Christoph; Mundt, Torsten; Stark, Helmut; Heinemann, Friedhelm

2014-02-01

In recent years, the application of small-diameter and mini dental implants to support removable and fixed prosthesis has dramatically increased. However, the success of these implants under functional biting forces and the reaction of the bone around them need to be analyzed. This review was aimed to present studies that deal with the fatigue life of small-diameter and mini dental implants under normal biting force, and their survival rate. The numerical and experimental studies concluded that an increase in the risk of bone damage or implant failure may be assumed in critical clinical situations and implants with <3 mm diameter have a risk of fracture in clinical practice. The survival rate of the small-diameter and mini dental implants over 5 years was 98.3-99.4%.

Chest diameter ratios for detecting static hyperinflation in children using photogrammetry.

PubMed

Ricieri, Denise da V; Rosário, Nelson A; Costa, Jecilene R

2008-01-01

To develop a photogrammetric method capable of identifying increases in anteroposterior chest diameters suggestive of pulmonary hyperinflation, and to test it with both asthmatic and asthma-free children. Two distinct study designs were used to achieve these two objectives. The first was a descriptive analysis of diameters measured at the height of the axilla and of the xiphoid on digital images of 56 children aged 8 to 12 years photographed in the orthostatic position. The second was a case-control study of (a) 19 asthmatic children in treatment for at least 12 months; and (b) 37 children free from asthma with no prior history of complaints of respiratory/allergic disease. Diameters were measured on images of the front and left side views using CorelDRAW, and the ratio between the front and side diameters was calculated for the axillary and xiphoid measurements, providing the diameter ratios. Diameter ratios close to or greater than 1 represent geometry tending towards a cylindrical shape, typical of hyperinflation on radiographs. Analysis with the t test for independent samples revealed a mean diameter ratio at the sternum that was significantly greater in the group of asthmatic children (p < 0.01) than the mean for the whole sample and also than the mean for the children without asthma. Despite the existence of disagreement on the best instruments, methods and times for identifying hyperinflation, results indicate that a system using diameter ratios obtained by photogrammetry is a promising tool for the identification of a kinesiopathological manifestation that is known to determine air entrapment in asthma patients. Research that combines clinical data with longitudinal intrapatient follow-up will be necessary to establish the strength of the evidence found in this study.

Stress concentration in a cylindrical shell containing a circular hole.

NASA Technical Reports Server (NTRS)

Adams, N. J. I.

1971-01-01

The state of stress in a cylindrical shell containing a circular cutout was determined for axial tension, torsion, and internal pressure loading. The solution was obtained for the shallow shell equations by a variational method. The results were expressed in terms of a nondimensional curvature parameter which was a function of shell radius, shell thickness, and hole radius. The function chosen for the solution was such that when the radius of the cylindrical shell approaches infinity, the flat-plate solution was obtained. The results are compared with solutions obtained by more rigorous analytical methods, and with some experimental results. For small values of the curvature parameter, the agreement is good. For higher values of the curvature parameter, the present solutions indicate a limiting value of stress concentration, which is in contrast to previous results.

Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines

DOE PAGES

Andelman, Tamar; Gong, Yinyan; Neumark, Gertrude; ...

2007-01-01

A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm) nanorods were synthesized from trihexylamine, and large diameter (50–80 nm) nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green) emission of the photoluminescence (PL) spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.

Coupled microstrip line transverse electromagnetic resonator model for high-field magnetic resonance imaging.

PubMed

Bogdanov, G; Ludwig, R

2002-03-01

The performance modeling of RF resonators at high magnetic fields of 4.7 T and more requires a physical approach that goes beyond conventional lumped circuit concepts. The treatment of voltages and currents as variables in time and space leads to a coupled transmission line model, whereby the electric and magnetic fields are assumed static in planes orthogonal to the length of the resonator, but wave-like along its longitudinal axis. In this work a multiconductor transmission line (MTL) model is developed and successfully applied to analyze a 12-element unloaded and loaded microstrip line transverse electromagnetic (TEM) resonator coil for animal studies. The loading involves a homogeneous cylindrical dielectric insert of variable radius and length. This model formulation is capable of estimating the resonance spectrum, field distributions, and certain types of losses in the coil, while requiring only modest computational resources. The boundary element method is adopted to compute all relevant transmission line parameters needed to set up the transmission line matrices. Both the theoretical basis and its engineering implementation are discussed and the resulting model predictions are placed in context with measurements. A comparison between a conventional lumped circuit model and this distributed formulation is conducted, showing significant departures in the resonance response at higher frequencies. This MTL model is applied to simulate two small-bore animal systems: one of 7.5-cm inner diameter, tuned to 200 MHz (4.7 T for proton imaging), and one of 13.36-cm inner diameter, tuned to both 200 and 300 MHz (7 T). Copyright 2002 Wiley-Liss, Inc.

Experimental validation of the intrinsic spatial efficiency method over a wide range of sizes for cylindrical sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortiz-Ramŕez, Pablo, E-mail: rapeitor@ug.uchile.cl; Larroquette, Philippe; Camilla, S.

The intrinsic spatial efficiency method is a new absolute method to determine the efficiency of a gamma spectroscopy system for any extended source. In the original work the method was experimentally demonstrated and validated for homogeneous cylindrical sources containing {sup 137}Cs, whose sizes varied over a small range (29.5 mm radius and 15.0 to 25.9 mm height). In this work we present an extension of the validation over a wide range of sizes. The dimensions of the cylindrical sources vary between 10 to 40 mm height and 8 to 30 mm radius. The cylindrical sources were prepared using the referencemore » material IAEA-372, which had a specific activity of 11320 Bq/kg at july 2006. The obtained results were better for the sources with 29 mm radius showing relative bias lesser than 5% and for the sources with 10 mm height showing relative bias lesser than 6%. In comparison with the obtained results in the work where we present the method, the majority of these results show an excellent agreement.« less

Design of a simple cryogenic system for ultraviolet-visible absorption spectroscopy with a back-reflectance fiber optic probe.

PubMed

Vinyard, Andrew; Hansen, Kaj A; Byrd, Ross; Stuart, Douglas A; Hansen, John E

2014-01-01

We report a convenient and inexpensive technique for the rapid acquisition of absorption spectra from small samples at cryogenic temperatures using a home built cryostat with novel collection optics. A cylindrical copper block was constructed with a coaxial bore to hold a 4.00 mm diameter electron paramagnetic resonance (EPR) tube and mounted on a copper feed in thermal contact with liquid nitrogen. A 6.35 mm diameter hole was bored into the side of the cylinder so a fiber optic cable bundle could be positioned orthogonally to the EPR tube. The light passing through the sample is reflected off of the opposing surfaces of the EPR tube and surrounding copper, back through the sample. The emergent light is then collected using the fiber optic bundle and analyzed using a dispersive spectrometer. Absorption spectra for KMnO4 were measured between 400 and 700 nm. Absorption intensity at 506, 525, 545, and 567 nm was found to be proportional to concentration, displaying Beer's law-like behavior. The EPR tube had an internal diameter of 3.2 mm; the double pass of the probe beam through the sample affords a central path length of about 6.4 mm. Comparing these measurements with those recorded on a conventional tabletop spectrometer using a cuvette with a 10.00 mm path length, we consistently found a ratio between intensities of 0.58 rather than the anticipated 0.64. These 6% smaller values we attribute to the curvature of the EPR tube and transmission/reflection losses. This system is particularly well-suited to studying the kinetics and dynamics of chemical reactions at cryogenic temperatures. The rapid response (100 ms) and multiplex advantage provided the opportunity of recording simultaneous time courses at several wavelengths following initiation of a chemical reaction with a pulsed laser source.

Buckling Test Results and Preliminary Test and Analysis Correlation from the 8-Foot-Diameter Orthogrid-Stiffened Cylinder Test Article TA02

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Waters, W. Allen, Jr.; Haynie, Waddy T.; Thornburgh, Robert P

2017-01-01

Results from the testing of cylinder test article SBKF-P2-CYL-TA02 (referred to herein as TA02) are presented. TA02 is an 8-foot-diameter (96-inches), 78.0-inch-long, aluminum-lithium (Al-Li), orthogrid-stiffened cylindrical shell similar to those used in current state-of-the-art launch-vehicle structures and was designed to exhibit global buckling when subjected to combined compression and bending loads. The testing was conducted at the Marshall Space Flight Center (MSFC), February 3-6, 2009, in support of the Shell Buckling Knockdown Factor Project (SBKF). The test was used to verify the performance of a newly constructed buckling test facility at MSFC and to verify the test article design and analysis approach used by the SBKF researchers.

Use of vacuum arc plasma guns for a metal puff Z-pinch system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rousskikh, A. G.; Zhigalin, A. S.; Oreshkin, V. I.

The performance of a metal puff Z-pinch system has been studied experimentally. In this type of system, the initial cylindrical shell 4 cm in diameter was produced by ten plasma guns. Each gun initiates a vacuum arc operating between magnesium electrodes. The net current of the guns was 80 kA. The arc-produced plasma shell was compressed by using a 450-kA, 450-ns driver, and as a result, a plasma column 0.3 cm in diameter was formed. The electron temperature of the plasma reached 400 eV at an average ion concentration of 1.85 {center_dot} 10{sup 18} cm{sup -3}. The power of themore » Mg K-line radiation emitted by the plasma for 15-30 ns was 300 MW/cm.« less

Modeling of axial vibrational control technique for CdTe VGF crystal growth under controlled cadmium partial pressure

NASA Astrophysics Data System (ADS)

Avetissov, I.; Kostikov, V.; Meshkov, V.; Sukhanova, E.; Grishechkin, M.; Belov, S.; Sadovskiy, A.

2014-01-01

A VGF growth setup assisted by axial vibrations of baffle submerged into CdTe melt with controlled Cd partial pressure was designed. An influence of baffle shape on flow velocity map, temperature distribution in CdTe melt and interface shape of growing crystal was analyzed by numerical simulation and physical modeling. To produce the desirable shape of crystal melt interface we slant under different angles vertical generatrix in a cylindrical disk and made chasing on faceplates of a disk. It was ascertained that a disk with conical generatrix formed more intensive convective flows from a faceplate with larger diameter. It was shown that at CdTe VGF crystal growth rate about 10 mm/h application of AVC technique made it possible to produce convex interface for 2 in. crystal diameter.

Mechanical properties of woven glass fiber-reinforced composites.

PubMed

Kanie, Takahito; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

2006-06-01

The aim of this investigation was to measure the flexural and compressive strengths and the corresponding moduli of cylindrical composite specimens reinforced with woven glass fiber. Test specimens were made by light-curing urethane dimethacrylate oligomer with woven glass fiber of 0.18-mm standard thickness. Tests were conducted using four reinforcement methods and two specimen diameters. Flexural strength and modulus of woven glass fiber-reinforced specimens were significantly greater than those without woven glass fiber (p < 0.01). Likewise, compressive strength of reinforced specimens was significantly greater than those without woven glass fiber (p < 0.01), except for specimens reinforced with woven glass fiber oriented at a tilt direction in the texture (p > 0.05). In terms of comparison between the two specimen diameters, no statistically significant differences in flexural strength and compressive strength (p > 0.05) were observed.

Buckling test of a 3-meter-diameter corrugated graphite-epoxy ring-stiffened cylinder

NASA Technical Reports Server (NTRS)

Davis, R. C.

1982-01-01

A three m diameter by three m long corrugated cylindrical shell with external stiffening rings was tested to failure by buckling. The corrugation geometry for the graphite epoxy composite cylinder wall was optimized to withstand a compressive load producing an ultimate load intensity of 157.6 kN/m without buckling. The test method used to produce the design load intensity was to mount the specimen as a cantilevered cylinder and apply a pure bending moment to the end. A load introduction problem with the specimen was solved by using the BOSOR 4 shell of revolution computer code to analyze the shell and attached loading fixtures. The cylinder test loading achieved was 101 percent of design ultimate, and the resulting mass per unit of shell wall area was 1.96 kg/sq m.

Space Station

NASA Image and Video Library

1972-01-01

This is an artist's concept of a modular space station. In 1970 the Marshall Space Flight Center arnounced the completion of a study concerning a modular space station that could be launched by the planned-for reusable Space Shuttle. The study envisioned a space station composed of cylindrical sections 14 feet in diameter and of varying lengths joined to form any one of a number of possible shapes. The sections were restricted to 14 feet in diameter and 58 feet in length to be consistent with a shuttle cargo bay size of 15 by 60 feet. Center officials said that the first elements of the space station could be in orbit by about 1978 and could be manned by three or six men. This would be an interim space station with sections that could be added later to form a full 12-man station by the early 1980s.

Self-formed cylindrical microcapillaries through surface migration of silicon and their application to single-cell analysis

NASA Astrophysics Data System (ADS)

Zeng, Fan; Luo, Yuan; Yobas, Levent; Wong, Man

2013-05-01

Surface migration of monocrystalline silicon has been applied to demonstrate self-formed cylindrical microcapillaries with diameters from 0.8 to 2.8 µm based on the microstructured substrate topography. The microcapillaries are entirely enclosed in silicon and can be conveniently etched to create fluidic access ports and microchannels for their subsequent integration into functional microfluidic devices. Moreover, the microcapillaries can be thermally oxidized through their access ports with silica walls remain intact upon release from surrounding silicon in an effort to enhance optical clarity. Straight microcapillaries and microcapillaries with perpendicular turns and crossings (junctions) have all been fabricated and validated for fluidic continuity with a fluorescein solution pumped through. The utility of the microcapillaries has been showcased on particle traps in which biological cells are probed for single-cell impedance spectroscopy. The approach disclosed, given its full compatibility with semiconductor device fabrication, offers great potential towards intelligent cell and molecule-based devices merging microelectronics and microfluidics.

Design and fabrication of optical homogenizer with micro structure by injection molding process

NASA Astrophysics Data System (ADS)

Chen, C.-C. A.; Chang, S.-W.; Weng, C.-J.

2008-08-01

This paper is to design and fabricate an optical homogenizer with hybrid design of collimator, toroidal lens array, and projection lens for beam shaping of Gaussian beam into uniform cylindrical beam. TracePro software was used to design the geometry of homogenizer and simulation of injection molding was preceded by Moldflow MPI to evaluate the mold design for injection molding process. The optical homogenizer is a cylindrical part with thickness 8.03 mm and diameter 5 mm. The micro structure of toroidal array has groove height designed from 12 μm to 99 μm. An electrical injection molding machine and PMMA (n= 1.4747) were selected to perform the experiment. Experimental results show that the optics homogenizer has achieved the transfer ratio of grooves (TRG) as 88.98% and also the optical uniformity as 68% with optical efficiency as 91.88%. Future study focuses on development of an optical homogenizer for LED light source.

Velocity profile of water vapor inside a cavity with two axial inlets and two outlets

NASA Astrophysics Data System (ADS)

Guadarrama-Cetina, José; Ruiz Chavarría, Gerardo

2014-03-01

To study the dynamics of Breath Figure phenomenon, a control of both the rate of flow and temperature of water vapor is required. The experimental setup widely used is a non hermetically closed chamber with cylindrical geometry and axial inlets and outlets. In this work we present measurements in a cylindrical chamber with diameter 10 cm and 1.5 cm height, keeping a constant temperature (10 °C). We are focused in the velocity field when a gradient of the temperatures is produced between the base plate and the vapor. With a flux of water vapor of 250 mil/min at room temperature (21 °C), the Reynolds number measured in one inlet is 755. Otherwise, the temperatures of water vapor varies from 21 to 40 °C. The velocity profile is obtained by hot wire anemometry. We identify the stagnations and the possibly instabilities regions for an empty plate and with a well defined shape obstacle as a fashion sample. Facultad de Ciencias, UNAM.

Propagation of Sound at Moderate and High Intensities in Absorbent and Hard-Walled Cylindrical Ducts. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Mcdaniel, Oliver Herbert

1975-01-01

The propagation of plane wave and higher order acoustic modes in both hard-walled and absorbent cylindrical ducts was studied at moderate sound intensities where the linear wave equation is valid, and at high intensities where nonlinear effects can be observed. The experiments were conducted with an anechoically terminated twelve-inch inside-diameter transite pipe. Various types of sound sources were mounted at one end of the duct to generate the desired acoustic fields within the duct. Arrays of conventional loudspeakers were used to generate plane waves and higher order acoustic modes at moderate intensities, and an array of four high intensity electro-pneumatic sound sources was used for the experiments in the nonlinear region. The attenuation of absorbent liners made of several different materials was obtained at moderate intensities for both plane waves and high order modes. It was found that the characteristics of the liners studied did not change appreciably at high intensities.

Exploring the Electronic Structure and Chemical Homogeneity of Individual Bi2Te3 Nanowires by Nano-Angle-Resolved Photoemission Spectroscopy.

PubMed

Krieg, Janina; Chen, Chaoyu; Avila, José; Zhang, Zeying; Sigle, Wilfried; Zhang, Hongbin; Trautmann, Christina; Asensio, Maria Carmen; Toimil-Molares, Maria Eugenia

2016-07-13

Due to their high surface-to-volume ratio, cylindrical Bi2Te3 nanowires are employed as model systems to investigate the chemistry and the unique conductive surface states of topological insulator nanomaterials. We report on nanoangle-resolved photoemission spectroscopy (nano-ARPES) characterization of individual cylindrical Bi2Te3 nanowires with a diameter of 100 nm. The nanowires are synthesized by electrochemical deposition inside channels of ion-track etched polymer membranes. Core level spectra recorded with submicron resolution indicate a homogeneous chemical composition along individual nanowires, while nano-ARPES intensity maps reveal the valence band structure at the single nanowire level. First-principles electronic structure calculations for chosen crystallographic orientations are in good agreement with those revealed by nano-ARPES. The successful application of nano-ARPES on single one-dimensional nanostructures constitutes a new avenue to achieve a better understanding of the electronic structure of topological insulator nanomaterials.

Rail-type gas switch with preionization by an additional corona discharge

NASA Astrophysics Data System (ADS)

Belozerov, O. S.; Krastelev, E. G.

2017-05-01

Results of an experimental research of a rail-type gas switch with preionization by an additional negative corona discharge are presented. The most of measurements were performed for an air insulated two-electrode switch assembled of cylindrical electrodes of 22 mm diameter and 100 mm length, arranged parallel to each other, with a spark gap between them varying from 6 to 15 mm. A set of 1 to 5 needles connected to a negative cylindrical electrode and located aside of them were used for corona discharges. The needle positions, allowing an effecient stabilization of the pulsed breakdown voltage and preventing the a transition of the corona discharge in a spark form, were found. It was shown that the gas preionization by the UV-radiation of the parallel corona discharge provides a stable operation of the switch with low variations of the pulsed breakdown voltage, not exceeding 1% for a given voltage rise-time tested within the range from 40 ns to 5 µs.

Paragnomoxyala gen. nov. (Xyalidae, Monhysterida, Nematoda) from the East China Sea.

PubMed

Jiang, Weijun; Huang, Yong

2015-11-05

A new genus, Paragnomoxyala gen. nov., and a new species, Paragnomoxyala breviseta sp. nov. are described from the East China Sea. Paragnomoxyala gen. nov. is characterized by having large funnel-shaped buccal cavity with cuticularized walls and extended anteriorly; lips very high; striated cuticle; four cephalic setae, absence of outer labial setae; circular amphidial fovea; straight spicules and absence of gubernaculum; tail conico-cylindrical with three terminal setae; female monodelphic with an anterior outstretched ovary. It differs from similar genera by having a large buccal cavity unique in Xyalidae, straight spicules, lacking gubernaculum, and conico-cylindrical tail with terminal setae. Paragnomoxyala breviseta sp. nov. is characterized by having a large funnel-shaped buccal cavity, with cuticularized walls and extended anteriorly, 1.6-1.8 hd long and 63-79% cbd wide; four cephalic setae 3-4 µm long; circular amphids 6-9 µm in diameter; spicules straight but slightly bent at both ends; absence of gubernaculum and precloacal supplement.

Small tractors for harvesting fuelwood in low-volume small-diameter hardwood stands

Treesearch

Neil K. Huyler; Chris B. LeDoux

1989-01-01

Much of the nonindustrial, private forest land in the Northeast is characterized by small diameter trees with low volume. Conventional harvesting systems used in logging these stands generally results in submarginal economic returns. Often, small-scale harvesting systems have economic advantages in these areas. Time and motion studies were conducted for several small...

Improving the accuracy of ionization chamber dosimetry in small megavoltage x-ray fields

NASA Astrophysics Data System (ADS)

McNiven, Andrea L.

The dosimetry of small x-ray fields is difficult, but important, in many radiation therapy delivery methods. The accuracy of ion chambers for small field applications, however, is limited due to the relatively large size of the chamber with respect to the field size, leading to partial volume effects, lateral electronic disequilibrium and calibration difficulties. The goal of this dissertation was to investigate the use of ionization chambers for the purpose of dosimetry in small megavoltage photon beams with the aim of improving clinical dose measurements in stereotactic radiotherapy and helical tomotherapy. A new method for the direct determination of the sensitive volume of small-volume ion chambers using micro computed tomography (muCT) was investigated using four nominally identical small-volume (0.56 cm3) cylindrical ion chambers. Agreement between their measured relative volume and ionization measurements (within 2%) demonstrated the feasibility of volume determination through muCT. Cavity-gas calibration coefficients were also determined, demonstrating the promise for accurate ion chamber calibration based partially on muCT. The accuracy of relative dose factor measurements in 6MV stereotactic x-ray fields (5 to 40mm diameter) was investigated using a set of prototype plane-parallel ionization chambers (diameters of 2, 4, 10 and 20mm). Chamber and field size specific correction factors ( CSFQ ), that account for perturbation of the secondary electron fluence, were calculated using Monte Carlo simulation methods (BEAM/EGSnrc simulations). These correction factors (e.g. CSFQ = 1.76 (2mm chamber, 5mm field) allow for accurate relative dose factor (RDF) measurement when applied to ionization readings, under conditions of electronic disequilibrium. With respect to the dosimetry of helical tomotherapy, a novel application of the ion chambers was developed to characterize the fan beam size and effective dose rate. Characterization was based on an adaptation of the computed tomography dose index (CTDI), a concept normally used in diagnostic radiology. This involved experimental determination of the fan beam thickness using the ion chambers to acquire fan beam profiles and extrapolation to a 'zero-size' detector. In conclusion, improvements have been made in the accuracy of small field dosimetry measurements in stereotactic radiotherapy and helical tomotherapy. This was completed through introduction of an original technique involving micro-CT imaging for sensitive volume determination and potentially ion chamber calibration coefficients, the use of appropriate Monte Carlo derived correction factors for RDF measurement, and the exploitation of the partial volume effect for helical tomotherapy fan beam dosimetry. With improved dosimetry for a wide range of challenging small x-ray field situations, it is expected that the patient's radiation safety will be maintained, and that clinical trials will adopt calibration protocols specialized for modern radiotherapy with small fields or beamlets. Keywords. radiation therapy, ionization chambers, small field dosimetry, stereotactic radiotherapy, helical tomotherapy, micro-CT.

Measurements of characteristic parameters of extremely small cogged wheels with low module by means of low-coherence interferometry

NASA Astrophysics Data System (ADS)

Pakula, Anna; Tomczewski, Slawomir; Skalski, Andrzej; Biało, Dionizy; Salbut, Leszek

2010-05-01

This paper presents novel application of Low Coherence Interferometry (LCI) in measurements of characteristic parameters as circular pitch, foot diameter, heads diameter, in extremely small cogged wheels (cogged wheel diameter lower than θ=3 mm and module m = 0.15) produced from metal and ceramics. The most interesting issue concerning small diameter cogged wheels occurs during their production. The characteristic parameters of the wheel depend strongly on the manufacturing process and while inspecting small diameter wheels the shrinkage during the cast varies with the slight change of fabrication process. In the paper the LCI interferometric Twyman - Green setup with pigtailed high power light emitting diode, for cogged wheels measurement, is described. Due to its relatively big field of view the whole wheel can be examined in one measurement, without the necessity of numerical stitching. For purposes of small cogged wheel's characteristic parameters measurement the special binarization algorithm was developed and successfully applied. At the end the results of measurement of heads and foot diameters of two cogged wheels obtained by proposed LCI setup are presented and compared with the results obtained by the commercial optical profiler. The results of examination of injection moulds used for fabrication of measured cogged wheels are also presented. Additionally, the value of cogged wheels shrinkage is calculated as a conclusion for obtained results. Proposed method is suitable for complex measurements of small diameter cogged wheels with low module especially when there are no measurements standards for such objects.

Isotachophoresis system having larger-diameter channels flowing into channels with reduced diameter and with selectable counter-flow

DOEpatents

Mariella, Jr., Raymond P.

2018-03-06

An isotachophoresis system for separating a sample containing particles into discrete packets including a flow channel, the flow channel having a large diameter section and a small diameter section; a negative electrode operably connected to the flow channel; a positive electrode operably connected to the flow channel; a leading carrier fluid in the flow channel; a trailing carrier fluid in the flow channel; and a control for separating the particles in the sample into discrete packets using the leading carrier fluid, the trailing carrier fluid, the large diameter section, and the small diameter section.

Stress-induced phase sensitivity of small diameter polarization maintaining solid-core photonic crystal fibre

NASA Astrophysics Data System (ADS)

Zhang, Zhihao; Zhang, Chunxi; Xu, Xiaobin

2017-09-01

Small diameter (cladding and coating diameter of 100 and 135 μm) polarization maintaining photonic crystal fibres (SDPM-PCFs) possess many unique properties and are extremely suitable for applications in fibre optic gyroscopes. In this study, we have investigated and measured the stress characteristics of an SDPM-PCF using the finite-element method and a Mach-Zehnder interferometer, respectively. Our results reveal a radial and axial sensitivity of 0.315 ppm/N/m and 25.2 ppm per 1 × 105 N/m2, respectively, for the SDPM-PCF. These values are 40% smaller than the corresponding parameters of conventional small diameter (cladding and coating diameter of 80 and 135 μm) panda fibres.

Small bowel dilation in children with short bowel syndrome is associated with mucosal damage, bowel-derived bloodstream infections, and hepatic injury.

PubMed

Hukkinen, Maria; Mutanen, Annika; Pakarinen, Mikko P

2017-09-01

Liver disease occurs frequently in short bowel syndrome. Whether small bowel dilation in short bowel syndrome could influence the risk of liver injury through increased bacterial translocation remains unknown. Our aim was to analyze associations between small bowel dilation, mucosal damage, bloodstream infections, and liver injury in short bowel syndrome patients. Among short bowel syndrome children (n = 50), maximal small bowel diameter was measured in contrast series and expressed as the ratio to the height of the fifth lumbar vertebra (small bowel diameter ratio), and correlated retrospectively to fecal calprotectin and plasma citrulline-respective markers of mucosal inflammation and mass-bloodstream infections, liver biochemistry, and liver histology. Patients with pathologic small bowel diameter ratio >2.17 had increased fecal calprotectin and decreased citrulline (P < .04 each). Of 33 bloodstream infections observed during treatment with parenteral nutrition, 16 were caused by intestinal bacteria, cultured 15 times more frequently when small bowel diameter ratio was >2.17 (P < .001). Intestinal bloodstream infections were predicted by small bowel diameter ratio (odds ratio 1.88, P = .017), and their frequency decreased after operative tapering procedures (P = .041). Plasma bilirubin concentration, gamma-glutamyl transferase activity, and histologic grade of cholestasis correlated with small bowel diameter ratio (0.356-0.534, P < .014 each), and were greater in the presence of intestinal bloodstream infections (P < .001 for all). Bloodstream infections associated with portal inflammation, cholestasis, and fibrosis grades (P < .031 for each). In linear regression, histologic cholestasis was predicted by intestinal bloodstream infections, small bowel diameter ratio, and parenteral nutrition (β = 0.36-1.29; P < .014 each), while portal inflammation by intestinal bloodstream infections only (β = 0.62; P = .033). In children with short bowel syndrome, small bowel dilation correlates with mucosal damage, bloodstream infections of intestinal origin, and cholestatic liver injury. In addition to parenteral nutrition, small bowel dilation and intestinal bloodstream infections contribute to development of short bowel syndrome-associated liver disease. Copyright © 2017 Elsevier Inc. All rights reserved.

Establishing a Mouse Model of a Pure Small Fiber Neuropathy with the Ultrapotent Agonist of Transient Receptor Potential Vanilloid Type 1.

PubMed

Lee, Yi-Chen; Lu, Shui-Chin; Hsieh, Yu-Lin

2018-02-13

Patients with diabetes mellitus (DM) or those experiencing the neurotoxic effects of chemotherapeutic agents may develop sensation disorders due to degeneration and injury of small-diameter sensory neurons, referred to as small fiber neuropathy. Present animal models of small fiber neuropathy affect both large- and small-diameter sensory fibers and thus create a neuropathology too complex to properly assess the effects of injured small-diameter sensory fibers. Therefore, it is necessary to develop an experimental model of pure small fiber neuropathy to adequately examine these issues. This protocol describes an experimental model of small fiber neuropathy specifically affecting small-diameter sensory nerves with resiniferatoxin (RTX), an ultrapotent agonist of transient receptor potential vanilloid type 1 (TRPV1), through a single dose of intraperitoneal injection, referred to as RTX neuropathy. This RTX neuropathy showed pathological manifestations and behavioral abnormalities that mimic the clinical characteristics of patients with small fiber neuropathy, including intraepidermal nerve fiber (IENF) degeneration, specifically injury in small-diameter neurons, and induction of thermal hypoalgesia and mechanical allodynia. This protocol tested three doses of RTX (200, 50, and 10 µg/kg, respectively) and concluded that a critical dose of RTX (50 µg/kg) is required for the development of typical small fiber neuropathy manifestations, and prepared a modified immunostaining procedure to investigate IENF degeneration and neuronal soma injury. The modified procedure is fast, systematic, and economic. Behavioral evaluation of neuropathic pain is critical to reveal the function of small-diameter sensory nerves. The evaluation of mechanical thresholds in experimental rodents is particularly challenging and this protocol describes a customized metal mesh that is suitable for this type of assessment in rodents. In summary, RTX neuropathy is a new and easily established experimental model to evaluate the molecular significance and intervention underlying neuropathic pain for the development of therapeutic agents.

Gallium ion-assisted room temperature synthesis of small-diameter ZnO nanorods.

PubMed

Cho, Seungho; Kim, Semi; Lee, Kun-Hong

2011-09-15

We report a method for synthesizing small-diameter ZnO nanorods at room temperature (20 °C), under normal atmospheric pressure (1 atm), and using a relatively short reaction time (1 h) by adding gallium salts to the reaction solution. The ZnO nanorods were, on average, 92 nm in length and 9 nm in diameter and were single crystalline in nature. Quantitative analyses revealed that gallium atoms were not incorporated into the synthesized nanocrystals. On the basis of the experimental results, we propose a mechanism for the formation of small-diameter ZnO nanorods in the presence of gallium ions. The optical properties were probed by UV-Vis diffuse reflectance spectroscopy. The absorption band of the small-diameter ZnO nanorods was blue-shifted relative to the absorption band of the ~230 nm diameter ZnO nanorods (control samples). Control experiments demonstrated that the absence of metal ion-containing precipitants (except ZnO) at room temperature is essential, and that the ZnO nanorod diameter distributions were narrow for the stirred reaction solution and broad when prepared without stirring. Copyright © 2011 Elsevier Inc. All rights reserved.

PHYSICAL PROPERTIES OF LARGE AND SMALL GRANULES IN SOLAR QUIET REGIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu Daren; Xie Zongxia; Hu Qinghua

The normal mode observations of seven quiet regions obtained by the Hinode spacecraft are analyzed to study the physical properties of granules. An artificial intelligence technique is introduced to automatically find the spatial distribution of granules in feature spaces. In this work, we investigate the dependence of granular continuum intensity, mean Doppler velocity, and magnetic fields on granular diameter. We recognized 71,538 granules by an automatic segmentation technique and then extracted five properties: diameter, continuum intensity, Doppler velocity, and longitudinal and transverse magnetic flux density to describe the granules. To automatically explore the intrinsic structures of the granules in themore » five-dimensional parameter space, the X-means clustering algorithm and one-rule classifier are introduced to define the rules for classifying the granules. It is found that diameter is a dominating parameter in classifying the granules and two families of granules are derived: small granules with diameters smaller than 1.''44, and large granules with diameters larger than 1.''44. Based on statistical analysis of the detected granules, the following results are derived: (1) the averages of diameter, continuum intensity, and Doppler velocity in the upward direction of large granules are larger than those of small granules; (2) the averages of absolute longitudinal, transverse, and unsigned flux density of large granules are smaller than those of small granules; (3) for small granules, the average of continuum intensity increases with their diameters, while the averages of Doppler velocity, transverse, absolute longitudinal, and unsigned magnetic flux density decrease with their diameters. However, the mean properties of large granules are stable; (4) the intensity distributions of all granules and small granules do not satisfy Gaussian distribution, while that of large granules almost agrees with normal distribution with a peak at 1.04 I{sub 0}.« less

Venus small volcano classification and description

NASA Technical Reports Server (NTRS)

Aubele, J. C.

1993-01-01

The high resolution and global coverage of the Magellan radar image data set allows detailed study of the smallest volcanoes on the planet. A modified classification scheme for volcanoes less than 20 km in diameter is shown and described. It is based on observations of all members of the 556 significant clusters or fields of small volcanoes located and described by this author during data collection for the Magellan Volcanic and Magmatic Feature Catalog. This global study of approximately 10 exp 4 volcanoes provides new information for refining small volcano classification based on individual characteristics. Total number of these volcanoes was estimated to be 10 exp 5 to 10 exp 6 planetwide based on pre-Magellan analysis of Venera 15/16, and during preparation of the global catalog, small volcanoes were identified individually or in clusters in every C1-MIDR mosaic of the Magellan data set. Basal diameter (based on 1000 measured edifices) generally ranges from 2 to 12 km with a mode of 34 km, and follows an exponential distribution similar to the size frequency distribution of seamounts as measured from GLORIA sonar images. This is a typical distribution for most size-limited natural phenomena unlike impact craters which follow a power law distribution and continue to infinitely increase in number with decreasing size. Using an exponential distribution calculated from measured small volcanoes selected globally at random, we can calculate total number possible given a minimum size. The paucity of edifice diameters less than 2 km may be due to inability to identify very small volcanic edifices in this data set; however, summit pits are recognizable at smaller diameters, and 2 km may represent a significant minimum diameter related to style of volcanic eruption. Guest, et al, discussed four general types of small volcanic edifices on Venus: (1) small lava shields; (2) small volcanic cones; (3) small volcanic domes; and (4) scalloped margin domes ('ticks'). Steep-sided domes or 'pancake domes', larger than 20 km in diameter, were included with the small volcanic domes. For the purposes of this study, only volcanic edifices less than 20 km in diameter are discussed. This forms a convenient cutoff since most of the steep-sided domes ('pancake domes') and scalloped margin domes ('ticks') are 20 to 100 km in diameter, are much less numerous globally than are the smaller diameter volcanic edifices (2 to 3 orders of magnitude lower in total global number), and do not commonly occur in large clusters or fields of large numbers of edifices.

Impacts of environmental factors on the climbing behaviors of herbaceous stem-twiners.

PubMed

Hu, Liang; Chen, Youfang; Liu, Meicun

2017-11-01

The curvature of the helical trajectory formed by herbaceous stem-twiners has been hypothesized to be constant on uniformly sized cylindrical supports and remains constant on different supports varying in diameter. However, experimental studies on the constant curvature hypothesis have been very limited. Here, we tested the hypothesis in a series of experiments on five herbaceous stem-twiners ( Ipomoea triloba , Ipomoea nil , Phaseolus vulgaris , Vigna unguiculata, and Mikania micrantha ). We investigated how internode characteristics (curvature [β], diameter [ d ], and length [ L ]) and success rate (SR) of twining shoots would be affected by support thickness ( D ), temperature ( T ), illumination, and support inclination. The results showed that: (1) the SR of tested species decreased, but d increased with increasing support thickness. The β of the twining shoots on erect cylindrical poles was not constant, but it decreased with increasing d or support thickness. (2) The SR of tested species was not obviously reduced under low-temperature conditions, but their β was significantly higher and d significantly lower when temperature was more than 5°C lower. (3) The SR , d, and L of two tested Ipomoea species significantly declined, but β increased under 50% shading stress. (4) The curvatures of upper semicycles of I. triloba shoots on 45° inclined supports were not significantly different from curvatures of those shoots climb on erect supports, whereas the curvatures of lower semicycles were 40%-72% higher than curvatures of upper semicycles. Synthesis : Our study illustrates that stem curvatures of a certain herbaceous stem-twiners are not constant, but rather vary in response to external support, temperature, and illumination conditions. We speculate that herbaceous stem-twiners positively adapt to wide-diameter supports by thickening their stems and by reducing their twining curvatures. This insight helps us better understand climbing processes and dynamics of stem-twiners in forest communities and ecosystems.

Initiation and Activation of Faults in Dry and Wet Rock by Fluid Injection

NASA Astrophysics Data System (ADS)

Stanchits, S.; Mayr, S.; Shapiro, S. A.; Dresen, G.

2008-12-01

We studied fracturing of rock samples induced by water injection in axial compression tests on cylindrical specimens of Flechtingen sandstone and Aue granite of 50 mm diameter and 105-125 mm length. Samples were intact solid rock cylinders and cylinders with central boreholes of 5 mm diameter and 52 mm length or through-boreholes of 2.5 mm diameter. To monitor acoustic emissions (AE) and ultrasonic velocities, twelve P-wave and six polarized S-wave sensors were glued to the cylindrical surface of the rock. Full waveforms were stored in a 12 channel transient recording system (PROEKEL, Germany). Polarity of AE first motion was used to discriminate source types associated with tensile, shear and pore-collapse cracking. To monitor strain, two pairs of orthogonally oriented strain-gages were glued onto the specimen surface. Samples were deformed in two consecutive loading steps: 1) Initial triaxial loading was performed at 20-50 MPa confining pressure on dry (under vacuum) or fully saturated samples until the yield point was reached. 2) In a second stage distilled water was injected into the samples with pore pressure increasing up to 20 MPa. For saturated samples the pore pressure was increased in steps and in periodic pulses. Injection of water into dry porous sandstone resulted in propagation of an AE hypocenter cloud closely linked to propagation of the water front. Position of the migrating water front was estimated from ultrasonic velocity measurements and measurements of the injected water volume. Propagation rate of AE-induced cloud parallel to bedding was higher than perpendicular to bedding, possibly related to permeability anisotropy. Nucleation of a brittle shear fault occurred at a critical pore pressure level with a nucleation patch located at the central borehole. Micro-structural analysis of fractured samples shows excellent agreement between location of AE hypocenters and macroscopic faults.

TH-CD-207B-10: Effect of CT Reconstruction Filter On Measured Hounsfield Values in Lung Nodules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Little, K; Reiser, I; Sanchez, A

Purpose: Measured Hounsfield numbers in CT are used by radiologists to determine the presence of calcium or fat in lung nodules, either of which suggests a benign diagnosis. However, substantial variations in Hounsfield number may arise due to the use of different reconstruction parameters such as the filter/kernel, leading to measurement inaccuracies. This quality improvement project was developed to demonstrate measurement pitfalls and to identify acceptable conditions for incorporating Hounsfield values as a factor in lung nodule diagnosis. Methods: 12 mm-diameter spheres of polyurethane and urethane foam were placed into an anthropomorphic chest phantom, and 10 mm-diameter tubes with varyingmore » iodine concentrations were placed into a 16 cm PMMA cylindrical phantom. Additionally, 11 mm-diameter PMMA and HDPE spheres were placed in a 10 cm PMMA cylindrical phantom. Phantoms were scanned at 120 kVp using a Siemens Biograph mCT and on a Philips iCT and reconstructed using various reconstruction filters. Results: For the Siemens system, both sharp kernels and smooth kernels altered the Hounsfield numbers. Hounsfield numbers varied within a range of 8.9 HU for urethane foam and varied within 58.7 HU for polyurethane. The iodine measurements varied up to 37.9 HU for the lowest concentration. For the Philips system, Hounsfield numbers were relatively consistent but were higher for the “Detail” and “Lung Enhanced” filters, varying by 36.9 HU for PMMA and 15.9 HU for HDPE. Conclusion: Reconstruction filters can change the measured Hounsfield numbers of nodular objects, especially with detail-enhancing (sharpening) filters commonly used in lung imaging. Measured values should only be used for diagnostic decision support with filters that have demonstrated accuracy and consistency. While filter accuracy statements are available from manufacturers, radiologists are likely not aware of the extent of potential variations that can occur in a clinical setting.« less

Quantifying the role that laboratory experiment sample scale has on observed material properties and mechanistic behaviors that cause well systems to fail

NASA Astrophysics Data System (ADS)

Huerta, N. J.; Fahrman, B.; Rod, K. A.; Fernandez, C. A.; Crandall, D.; Moore, J.

2017-12-01

Laboratory experiments provide a robust method to analyze well integrity. Experiments are relatively cheap, controlled, and repeatable. However, simplifying assumptions, apparatus limitations, and scaling are ubiquitous obstacles for translating results from the bench to the field. We focus on advancing the correlation between laboratory results and field conditions by characterizing how failure varies with specimen geometry using two experimental approaches. The first approach is designed to measure the shear bond strength between steel and cement in a down-scaled (< 3" diameter) well geometry. We use several cylindrical casing-cement-casing geometries that either mimic the scaling ratios found in the field or maximize the amount of metal and cement in the sample. We subject the samples to thermal shock cycles to simulate damage to the interfaces from operations. The bond was then measured via a push-out test. We found that not only did expected parameters, e.g. curing time, play a role in shear-bond strength but also that scaling of the geometry was important. The second approach is designed to observe failure of the well system due to pressure applied on the inside of a lab-scale (1.5" diameter) cylindrical casing-cement-rock geometry. The loading apparatus and sample are housed within an industrial X-ray CT scanner capable of imaging the system while under pressure. Radial tension cracks were observed in the cement after an applied internal pressure of 3000 psi and propagated through the cement and into the rock as pressure was increased. Based on our current suite of tests we find that the relationship between sample diameters and thicknesses is an important consideration when observing the strength and failure of well systems. The test results contribute to our knowledge of well system failure, evaluation and optimization of new cements, as well as the applicability of using scaled-down tests as a proxy for understanding field-scale conditions.

MO-FG-BRA-08: A Preliminary Study of Gold Nanoparticles Enhanced Diffuse Optical Tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, K; Dogan, N; Yang, Y

2015-06-15

Purpose: To develop an imaging method by using gold nanoparticles (GNP) to enhance diffuse optical tomography (DOT) for better tumor detection. Methods: Experiments were performed on a tissue-simulating cylindrical optical phantom (30mm diameter, 60mm length). The GNP used are gold nanorods (10nm diameter, 44nm length) with peak light absorption at 840nm. 0.085ml GNP colloid of 96nM concentration was loaded into a 6mm diameter cylindrical hole in the phantom. An 856nm laser beam (14mW) was used as light source to irradiate the phantom at multiple locations through rotating and elevating the phantom. A CCD camera captured the light transmission through themore » phantom for each irradiation with total 40 projections (8 rotation angles in 45degree steps and 5 elevations with 3mm apart). Cone beam CT of the phantom was used to generate the three-dimensional mesh for DOT reconstruction and to identify the true location of the GNP volume. A forward simulation was performed with known phantom optical properties to establish a relationship between the absorption coefficient and concentration of the GNP by matching the simulated and measured transmission. DOT image reconstruction was performed to restore the GNP within the phantom. In addition, a region-constrained reconstruction was performed by confining the solutions within the GNP volume detected from CT. Results: The position of the GNP volume was reconstructed with <2mm error. The reconstructed average GNP concentration within an identical volume was 104nM, 8% difference from the truth. When the CT was used as “a priori”, the reconstructed average GNP concentration was 239nM, about 2.5 times of the true concentration. Conclusion: This study is the first to demonstrate GNP enhanced DOT with phantom imaging. The GNP can be differentiated from their surrounding background. However, the reconstruction methods needs to be improved for better spatial and quantification accuracy.« less

Assembly of 5.5-Meter Diameter Developmental Barrel Segments for the Ares I Upper Stage

NASA Technical Reports Server (NTRS)

Carter, Robert W.

2011-01-01

Full scale assembly welding of Ares I Upper Stage 5.5-Meter diameter cryogenic tank barrel segments has been performed at the Marshall Space Flight Center (MSFC). One full-scale developmental article produced under the Ares 1 Upper Stage project is the Manufacturing Demonstration Article (MDA) Barrel. This presentation will focus on the welded assembly of this barrel section, and associated lessons learned. Among the MDA articles planned on the Ares 1 Program, the Barrel was the first to be completed, primarily because the process of manufacture from piece parts (barrel panels) utilized the most mature friction stir process planned for use on the Ares US program: Conventional fixed pin Friction Stir Welding (FSW). This process is in use on other space launch systems, including the Shuttle s External Tank, the Delta IV common booster core, the Delta II, and the Atlas V rockets. The goals for the MDA Barrel development were several fold: 1) to prove out Marshall Space Flight Center s new Vertical Weld Tool for use in manufacture of cylindrical barrel sections, 2) to serve as a first run for weld qualification to a new weld specification, and 3) to provide a full size cylindrical section for downstream use in precision cleaning and Spray-on Foam Insulation development. The progression leading into the welding of the full size barrel included sub scale panel welding, subscale cylinder welding, a full length confidence weld, and finally, the 3 seamed MDA barrel processing. Lessons learned on this MDA program have been carried forward into the production tooling for the Ares 1 US Program, and in the use of the MSFC VWT in processing other large scale hardware, including two 8.4 meter diameter Shuttle External Tank barrel sections that are currently being used in structural analysis to validate shell buckling models.

Nuclear characteristics of a fissioning uranium plasma test reactor with light-water cooling

NASA Technical Reports Server (NTRS)

Whitmarsh, C. L., Jr.

1973-01-01

An analytical study was performed to determine a design configuration for a cavity test reactor. Test section criteria were that an average flux of 10 to the 15th power neutrons/sq cm/sec (E less than or equal to 0.12 eV) be supplied to a 61-cm-diameter spherical cavity at 200-atm pressure. Design objectives were to minimize required driver power, to use existing fuel-element technology, and to obtain fuel-element life of 10 to 100 full-power hours. Parameter calculations were made on moderator region size and material, driver fuel arrangement, control system, and structure in order to determine a feasible configuration. Although not optimized, a configuration was selected which would meet design criteria. The driver fuel region was a cylindrical annular region, one element thick, of 33 MTR-type H2O-cooled elements (Al-U fuel plate configuration), each 101 cm long. The region between the spherical test cavity and the cylindrical driver fuel region was Be (10 vol. % H2O coolant) with a midplane dimension of 8 cm. Exterior to the driver fuel, the 25-cm-thick cylindrical and axial reflectors were also Be with 10 vol. % H2O coolant. The entire reactor was contained in a 10-cm-thick steel pressure vessel, and the 200-atm cavity pressure was equalized throughout the driver reactor. Fuel-element life was 50 hr at the required driver power of 200 MW. Reactor control would be achieved with rotating poison drums located in the cylindrical reflector region. A control range of about 18 percent delta k/k was required for reactor operation.

A new static sampler for airborne total dust in workplaces.

PubMed

Mark, D; Vincent, J H; Gibson, H; Lynch, G

1985-03-01

This paper describes the development and laboratory testing of a new static dust sampler for airborne total dust in workplaces. Particular attention is paid to designing the sampling head and entry consistent with the concept of inspirability which in turn defines a biologically-relevant aspiration efficiency. The sampling head has a small cylindrical body and a transverse entry slot with thin protruding lips forming an integral part of a weighable capsule containing a 37 mm filter which collects all of the sampled dust (without introducing errors due to external particle blow-off or internal wall losses). A battery-powered sampling pump provides both air suction at 3 L/min and rigid mounting for the sampling head. The sampling head is rotated continuously through 360 degrees at approximately 1.5 rpm by a simple electric drive, connected to the stationary pump through a rotating seal. Wind tunnel testing of the instrument showed it to display an entry efficiency very close to the inspirability curve of Vincent and Armbruster (now recommended by the ACGIH Technical Committee on Air Sampling Procedures for defining inspirable particulate matter (IPM] for particles of aerodynamic diameter up to 90 micron and for windspeeds in the range of one to three m/sec.

Pulsed plasma thruster by applied a high current hollow cathode discharge

NASA Astrophysics Data System (ADS)

Watanabe, Masayuki; N. Nogera Team; T. Kamada Team

2013-09-01

The pulsed plasma thruster applied by a high current hollow cathode discharge has been investigated. In this research, the pseudo-spark discharge (PSD), which is a one of a pulsed high current hollow cathode discharge, is applied to the plasma thruster. In PSD, the opposite surfaces of the anode and cathode have a small circular hole and the cathode has a cylindrical cavity behind the circular hole. To generate the high speed plasma flow, the diameter of the anode hole is enlarged as compared with that of the cathode hole. As a result, the plasma is accelerated by a combination of an electro-magnetic force and a thermo-dynamic force inside a cathode cavity. For the improvement of the plasma jet characteristic, the magnetic field is also applied to the plasma jet. To magnetize the plasma jet, the external magnetic field is directly induced nearby the electrode holes. Consequently, the plasma jet is accelerated with the self-azimuthal magnetic field. With the magnetic field, the temperature and the density of the plasma jet were around 5 eV and in the order of 10 19 m-3. The density increased several times as compared with that without the magnetic field.

Relationship between position of brain activity and change in optical density for NIR imaging

NASA Astrophysics Data System (ADS)

Kashio, Yoshihiko; Ono, Muneo; Firbank, Michael; Schweiger, Martin; Arridge, Simon R.; Okada, Eiji

2000-11-01

Multi-channel NIR system can obtain the topographic image of brain activity. Since the image is reconstructed from the change in optical density measured with the source-detector pairs, it is important to reveal the volume of tissue sampled by each source-detector pair. In this study, the light propagation in three-dimensional adult head model is calculated by hybrid radiosity-diffusion method. The model is a layered slab which mimics the extra cerebral tissue (skin, skull), CSF and brain. The change in optical density caused by the absorption change in a small cylindrical region of 10 mm in diameter at various positions in the brain is calculated. The greatest change in optical density can be observed when the absorber is located in the middle of the source and detector. When the absorber is located just below the source or detector, the change in optical density is almost half of that caused by the same absorber in the midpoint. The light propagation in the brain is strongly affected by the presence of non-scattering layer and consequently sensitive region is broadly distributed on the brain surface.

Carbon Nanotubes: Applications in Pharmacy and Medicine

PubMed Central

He, Hua; Pham-Huy, Lien Ai; Dramou, Pierre; Xiao, Deli; Zuo, Pengli

2013-01-01

Carbon nanotubes (CNTs) are allotropes of carbon, made of graphite and constructed in cylindrical tubes with nanometer in diameter and several millimeters in length. Their impressive structural, mechanical, and electronic properties are due to their small size and mass, their strong mechanical potency, and their high electrical and thermal conductivity. CNTs have been successfully applied in pharmacy and medicine due to their high surface area that is capable of adsorbing or conjugating with a wide variety of therapeutic and diagnostic agents (drugs, genes, vaccines, antibodies, biosensors, etc.). They have been first proven to be an excellent vehicle for drug delivery directly into cells without metabolism by the body. Then other applications of CNTs have been extensively performed not only for drug and gene therapies but also for tissue regeneration, biosensor diagnosis, enantiomer separation of chiral drugs, extraction and analysis of drugs and pollutants. Moreover, CNTs have been recently revealed as a promising antioxidant. This minireview focuses the applications of CNTs in all fields of pharmacy and medicine from therapeutics to analysis and diagnosis as cited above. It also examines the pharmacokinetics, metabolism and toxicity of different forms of CNTs and discusses the perspectives, the advantages and the obstacles of this promising bionanotechnology in the future. PMID:24195076

A high-current rail-type gas switch with preionization by an additional corona discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antipov, E. I.; Belozerov, O. S.; Krastelev, E. G., E-mail: ekrastelev@yandex.ru

The characteristics of a high-current rail-type gas switch with preionization of the gas (air) in a spark gap by an additional corona discharge are investigated. The experiments were performed in a voltage range of 10–45 kV using a two-electrode switch consisting of two cylindrical electrodes with a diameter of 22 mm and a length of 100 mm and a set of laterally located corona-discharge needles. The requirements for the position and size of the needles are defined for which a corona discharge is ignited before a breakdown of the main gap and does not change to a sparking form, andmore » the entire length of the rail electrodes is efficiently used. The fulfillment of these requirements ensures stable operation of the switch with a small variation of the pulse breakdown voltage, which is not more than 1% for a fixed voltage-pulse rise time in the range from 150 ns to 3.5 μs. A short delay time of the switch breakdown makes it possible to control the two-electrode switch by an overvoltage pulse of nanosecond duration.« less

A long-acting buprenorphine delivery system.

PubMed

Pontani, R B; Misra, A L

1983-03-01

A subcutaneously implantable buprenorphine delivery system utilizing cholesterol-glyceryltristearate matrix for prolonged release of drug is described. Implantable cylindrical pellets of buprenorphine (cholesterol 36 mg, glyceryltristearate 4 mg, buprenorphine hydrochloride 10 mg), diameter 3 mm, length 6 mm blocked the antinociceptive action (hot plate, 55 degrees C) of 10 mg kg-1 SC challenge dose of morphine in rats for 12 weeks or more (longer periods not evaluated). The cumulative percent release of buprenorphine from the test devices 2, 4, 6, 10 and 12 weeks after implantation was 27.4, 35.9, 37.6, 39.9 and 43.1, respectively. The release of buprenorphine from 10 mg pellets approximated first-order kinetics with half-lives of 0.85 and 50.24 weeks, for alpha and beta phases, respectively. The test devices possess the desirable characteristics of simplicity, biocompatibility, nontoxicity, ease of sterilization with ethylene oxide, small size for ease of insertion and removal, minimal encapsulation by surrounding tissue and an extended period of drug release unaffected by body metabolism. No side effects were seen in implanted rats which fed well and gained weight during entire treatment. Neither deterioration of implant nor any gross anatomic changes at implant site were apparent 12 weeks after pellet implantation.

Transition between bulk and surface refractive index sensitivity of micro-cavity in-line Mach-Zehnder interferometer induced by thin film deposition.

PubMed

Śmietana, Mateusz; Janik, Monika; Koba, Marcin; Bock, Wojtek J

2017-10-16

In this work we discuss the refractive index (RI) sensitivity of a micro-cavity in-line Mach-Zehnder interferometer in the form of a cylindrical hole (40-50 μm in diameter) fabricated in a standard single-mode optical fiber using a femtosecond laser. The surface of the micro-cavity was coated with up to 400 nm aluminum oxide thin film using the atomic layer deposition method. Next, the film was progressively chemically etched and the influence on changes in the RI of liquid in the micro-cavity was determined at different stages of the experiment, i.e., at different thicknesses of the film. An effect of transition between sensitivity to the film thickness (surface) and the RI of liquid in the cavity (bulk) is demonstrated for the first time. We have found that depending on the interferometer working conditions determined by thin film properties, the device can be used for investigation of phenomena taking place at the surface, such as in case of specific label-free biosensing applications, or for small-volume RI analysis as required in analytical chemistry.

Optical design of a robotic TV camera probe for minimally invasive abdominal surgery

NASA Astrophysics Data System (ADS)

Todaro, Susanna; He, Weiyi; Killinger, Dennis

2011-03-01

Minimally invasive techniques are a promising new field of surgery; however, they limit the surgeon's access points and maneuverability. In order to increase the number of access points in minimally invasive abdominal surgery, a proposed implantable medical probe braces to the abdominal wall and provides illumination and video signal. The probe is cylindrical, about 25 mm long and 10 mm in diameter. A ring of LEDs on the end of the probe illuminates the tissue, and the resulting image is focused onto an HD video detector. It was necessary to apply beam-shaping reflectors to collimate the light onto a small target area, to avoid illuminating areas not picked up by the video. These reflectors were designed and simulated using the optical ray tracing software TracePro. Two LED chip geometries and three types of reflector geometries were analyzed, and the parameters for each geometry were optimized. For the straight-edged reflectors, the intensity patterns and optimization were compared to experimental results. Although parabolic reflectors produced the best collimation, cone reflectors with a 20-degree half-angle produced significant collimation at a much cheaper price. This work was supported by NSF REU program (award No DMR-1004873).

A Local Condensation Analysis Representing Two-phase Annular Flow in Condenser/radiator Capillary Tubes

NASA Technical Reports Server (NTRS)

Karimi, Amir

1991-01-01

NASA's effort for the thermal environmental control of the Space Station Freedom is directed towards the design, analysis, and development of an Active Thermal Control System (ATCS). A two phase, flow through condenser/radiator concept was baselined, as a part of the ATCS, for the radiation of space station thermal load into space. The proposed condenser rejects heat through direct condensation of ATCS working fluid (ammonia) in the small diameter radiator tubes. Analysis of the condensation process and design of condenser tubes are based on the available two phase flow models for the prediction of flow regimes, heat transfer, and pressure drops. The prediction formulas use the existing empirical relationships of friction factor at gas-liquid interface. An attempt is made to study the stability of interfacial waves in two phase annular flow. The formulation is presented of a stability problem in cylindrical coordinates. The contribution of fluid viscosity, surface tension, and transverse radius of curvature to the interfacial surface is included. A solution is obtained for Kelvin-Helmholtz instability problem which can be used to determine the critical and most dangerous wavelengths for interfacial waves.

Flow of High Internal Phase Ratio Emulsions through Pipes

NASA Astrophysics Data System (ADS)

Kostak, K.; Özsaygı, R.; Gündüz, I.; Yorgancıoǧlu, E.; Tekden, E.; Güzel, O.; Sadıklar, D.; Peker, S.; Helvacı, Ş. Ş.

2015-04-01

The flow behavior of W/O type of HIPRE stabilized by hydrogen bonds with a sugar (sorbitol) in the aqueous phase, was studied. Two groups of experiments were done in this work: The effect of wall shear stresses were investigated in flow through pipes of different diameters. For this end, HIPREs prestirred at constant rate for the same duration were used to obtain similar drop size distributions. Existence and extent of elongational viscosity were used as a probe to elucidate the effect of drop size distribution on the flow behavior: HIPREs prestirred for the same duration at different rates were subjected to flow through converging pipes. The experimental flow curves for flow through small cylindrical pipes indicated four different stages: 1) initial increase in the flow rate at low pressure difference, 2) subsequent decrease in the flow rate due to capillary flow, 3) pressure increase after reaching the minimum flow rate and 4) slip flow after a critical pressure difference. HIPREs with sufficient external liquid phase in the plateau borders can elongate during passage through converging pipes. In the absence of liquid stored in the plateau borders, the drops rupture during extension and slip flow takes place without elongation.

Active Joint Mechanism Driven by Multiple Actuators Made of Flexible Bags: A Proposal of Dual Structural Actuator

PubMed Central

Inou, Norio

2013-01-01

An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input. PMID:24385868

Carbon nanotubes: applications in pharmacy and medicine.

PubMed

He, Hua; Pham-Huy, Lien Ai; Dramou, Pierre; Xiao, Deli; Zuo, Pengli; Pham-Huy, Chuong

2013-01-01

Carbon nanotubes (CNTs) are allotropes of carbon, made of graphite and constructed in cylindrical tubes with nanometer in diameter and several millimeters in length. Their impressive structural, mechanical, and electronic properties are due to their small size and mass, their strong mechanical potency, and their high electrical and thermal conductivity. CNTs have been successfully applied in pharmacy and medicine due to their high surface area that is capable of adsorbing or conjugating with a wide variety of therapeutic and diagnostic agents (drugs, genes, vaccines, antibodies, biosensors, etc.). They have been first proven to be an excellent vehicle for drug delivery directly into cells without metabolism by the body. Then other applications of CNTs have been extensively performed not only for drug and gene therapies but also for tissue regeneration, biosensor diagnosis, enantiomer separation of chiral drugs, extraction and analysis of drugs and pollutants. Moreover, CNTs have been recently revealed as a promising antioxidant. This minireview focuses the applications of CNTs in all fields of pharmacy and medicine from therapeutics to analysis and diagnosis as cited above. It also examines the pharmacokinetics, metabolism and toxicity of different forms of CNTs and discusses the perspectives, the advantages and the obstacles of this promising bionanotechnology in the future.

Active joint mechanism driven by multiple actuators made of flexible bags: a proposal of dual structural actuator.

PubMed

Kimura, Hitoshi; Matsuzaki, Takuya; Kataoka, Mokutaro; Inou, Norio

2013-01-01

An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input.

Measurement of the refractive index of microquantity liquid filled in a capillary and a capillary wall without destruction.

PubMed

Li, Qiang; Pu, Xiaoyun

2013-07-20

A method for measuring the refractive index (RI) of a small volume of liquid and a capillary wall is presented in this paper. A transparent capillary filled with liquid is used as a cylindrical positive lens; subsequently, the focal length of the lens is derived through the base of paraxial approximation, which is recorded as a function of the RIs of the liquid and capillary wall. With the RI of a capillary wall known, the RI of the liquid can be obtained by measuring the focal length of the lens, which is characterized by a microquantity liquid, spatial resolution, and easy operation. The RI of the capillary wall can be calculated without ruining the capillary if the capillary is filled with a standard liquid (RI is known), the deviation of which is less than 0.003 RIU. The factors affecting accuracy of the measurement, for instance, the depth of a field (DOF) in a reading microscope system and the outer and inner diameters of a capillary are analyzed, while illustrating that the effective DOF plays an essential role in accurate measurement.

Hyaluronic acid enhancement of expanded polytetrafluoroethylene for small diameter vascular grafts

NASA Astrophysics Data System (ADS)

Lewis, Nicole R.

Cardiovascular disease is the leading cause of mortality and morbidity in the United States and other developed countries. In the United States alone, 8 million people are diagnosed with peripheral arterial disease per year and over 250,000 patients have coronary bypass surgery each year. Autologous blood vessels are the standard graft used in small diameter (<6mm) arterial bypass procedures. Synthetic small diameter grafts have had limited success. While polyethylene (Dacron) and expanded polytetrafluoroethylene (ePTFE) are the most commonly used small diameter synthetic vascular graft materials, there are significant limitations that make these materials unfavorable for use in the low blood flow conditions of the small diameter arteries. Specifically, Dacron and ePTFE grafts display failure due to early thrombosis or late intimal hyperplasia. With the shortage of tissue donors and the limited supply of autologous blood vessels available, there is a need for a small diameter synthetic vascular graft alternative. The aim of this research is to create and characterize ePTFE grafts prepared with hyaluronic acid (HA), evaluate thrombogenic potential of ePTFE-HA grafts, and evaluate graft mechanical properties and coating durability. The results in this work indicate the successful production of ePTFE-HA materials using a solvent infiltration technique. Surface interactions with blood show increased platelet adhesion on HA-modified surfaces, though evidence may suggest less platelet activation and erythrocyte lysis. Significant changes in mechanical properties of HA-modified ePTFE materials were observed. Further investigation into solvent selection, uniformity of HA, endothelialization, and dynamic flow testing would be beneficial in the evaluation of these materials for use in small diameter vascular graft bypass procedures.

76 FR 67411 - Small Diameter Graphite Electrodes From the People's Republic of China: Extension of Time Limit...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-01

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-929] Small Diameter Graphite... diameter graphite electrodes from the People's Republic of China (PRC) for the period February 1, 2010... Graphite, Co. The preliminary results of the review are currently due no later than October 31, 2011...

Hexagonal Hollow Tube Based Energy Absorbing Crash Buffers for Roadside Fixed Objects

NASA Astrophysics Data System (ADS)

Uddin, M. S.; Amirah Shafie, Nurul; Zivkovic, Grad

2017-03-01

The purpose of this study was to investigate the deformation of the energy absorbing hexagonal hollow tubes in a lateral compression. The aim is to design cost effective and high energy-absorbing buffer systems, which are capable of controlling out-of-control vehicles in high-speed zones. A nonlinear quasi-static finite element analysis was applied to determine the deformation and energy absorption capacity. The main parameters in the design were diameter and wall thickness of the tubes. Experimental test simulating the lateral compressive loading on a single tube was performed. Results show that as the diameter and the thickness increase, the deformation strength increases. Hexagonal tube with diameter of 219 mm and thickness of 4 mm is shown to have the highest energy absorption capability. Compared to existing cylindrical and octagonal shapes, the hexagonal tubes show the highest energy absorption capacity. Hexagonal tubes therefore can be regarded as a potential candidate for buffer designs in high speed zones. In addition, they would be compact, cost effective and facilitate ease of installation.