Axial Length/Corneal Radius of Curvature Ratio and Refractive ...
African Journals Online (AJOL)
2018-02-07
Feb 7, 2018 ... Aim/Background: Associations between axial length (AL) to corneal radius of curvature (CR) ratio and refractive status in a healthy Nigerian adult population were studied. Materials and Methods: Healthy students and members of staff of Obafemi Awolowo Teaching Hospitals Complex, Ile-Ife, South West ...
Axial Length/Corneal Radius of Curvature Ratio and Refractive ...
African Journals Online (AJOL)
Aim/Background: Associations between axial length (AL) to corneal radius of curvature (CR) ratio and refractive status in a healthy Nigerian adult population were studied. Materials and Methods: Healthy students and members of staff of Obafemi Awolowo Teaching Hospitals Complex, Ile‑Ife, South West Nigeria, free of ...
Axial Length/Corneal Radius of Curvature Ratio and Refractive ...
African Journals Online (AJOL)
2017-12-05
Dec 5, 2017 ... variously described as determined by the ocular biometric variables. There have been many studies on the relationship between refractive error and ocular axial length (AL), anterior chamber depth, corneal radius of curvature (CR), keratometric readings as well as other ocular biometric variables such as ...
Axial length/corneal radius of curvature ratio and refractive status in ...
African Journals Online (AJOL)
Aim/Background: Associations between axial length (AL) to corneal radius of curvature (CR) ratio and refractive status in a healthy Nigerian adult population were studied. Materials and Methods: Healthy students and members of staff of Obafemi Awolowo Teaching Hospitals Complex, Ile‑Ife, South West Nigeria, free of ...
Jinghai, Zhou; Tianbei, Kang; Fengchi, Wang; Xindong, Wang
2017-11-01
Eight less stirrups in the core area frame joints are simulated by ABAQUS finite element numerical software. The composite reinforcement method is strengthened with carbon fiber and increasing column section, the axial compression ratio of reinforced specimens is 0.3, 0.45 and 0.6 respectively. The results of the load-displacement curve, ductility and stiffness are analyzed, and it is found that the different axial compression ratio has great influence on the bearing capacity of increasing column section strengthening method, and has little influence on carbon fiber reinforcement method. The different strengthening schemes improve the ultimate bearing capacity and ductility of frame joints in a certain extent, composite reinforcement joints strengthening method to improve the most significant, followed by increasing column section, reinforcement method of carbon fiber reinforced joints to increase the minimum.
Energy Technology Data Exchange (ETDEWEB)
Liu, Jianfang [Chinese Academy of Medical Sciences and Peking Union Medical College, National Cancer Center/Cancer Hospital, Beijing (China); Capital Medical University Electric Power Teaching Hospital, Beijing (China); Wang, Zhu; Qu, Dong; Yao, Libo [Chinese Academy of Medical Sciences and Peking Union Medical College, National Cancer Center/Cancer Hospital, Beijing (China); Shao, Huafei [Affiliated Yantai Yuhuangding Hospital of Qingdao University Medical College, Yantai (China); Liu, Jian [Meitan General Hospital, Beijing (China)
2018-01-15
To investigate the value of CT with inclusion of smaller lymph node (LN) sizes and axial ratio to improve the sensitivity in diagnosis of regional lymph node metastases in oesophageal squamous cell carcinoma (OSCC). The contrast-enhanced multidetector row spiral CT (MDCT) multiplanar reconstruction images of 204 patients with OSCC were retrospectively analysed. The long-axis and short-axis diameters of the regional LNs were measured and axial ratios were calculated (short-axis/long-axis diameters). Nodes were considered round if the axial ratio exceeded the optimal LN axial ratio, which was determined by receiver operating characteristic analysis. A positive predictive value (PPV) exceeding 50% is needed. This was achieved only with LNs larger than 9 mm in short-axis diameter, but nodes of this size were rare (sensitivity 37.3%, specificity 96.4%, accuracy 85.8%). If those round nodes (axial ratio exceeding 0.66) between 7 mm and 9 mm in size were considered metastases as well, it might improve the sensitivity to 67.2% with a PPV of 63.9% (specificity 91.6%, accuracy 87.2%). Combination of a smaller size and axial ratio for LNs in MDCT as criteria improves the detection sensitivity for LN metastases in OSCC. (orig.)
Invariant Imbedding T-Matrix Method for Axial Symmetric Hydrometeors with Extreme Aspect Ratios
Pelissier, C.; Clune, T.; Kuo, K. S.; Munchak, S. J.; Adams, I. S.
2017-12-01
The single-scattering properties (SSPs) of hydrometeors are the fundamental quantities for physics-based precipitation retrievals. Thus, efficient computation of their electromagnetic scattering is of great value. Whereas the semi-analytical T-Matrix methods are likely the most efficient for nonspherical hydrometeors with axial symmetry, they are not suitable for arbitrarily shaped hydrometeors absent of any significant symmetry, for which volume integral methods such as those based on Discrete Dipole Approximation (DDA) are required. Currently the two leading T-matrix methods are the Extended Boundary Condition Method (EBCM) and the Invariant Imbedding T-matrix Method incorporating Lorentz-Mie Separation of Variables (IITM+SOV). EBCM is known to outperform IITM+SOV for hydrometeors with modest aspect ratios. However, in cases when aspect ratios become extreme, such as needle-like particles with large height to diameter values, EBCM fails to converge. Such hydrometeors with extreme aspect ratios are known to be present in solid precipitation and their SSPs are required to model the radiative responses accurately. In these cases, IITM+SOV is shown to converge. An efficient, parallelized C++ implementation for both EBCM and IITM+SOV has been developed to conduct a performance comparison between EBCM, IITM+SOV, and DDSCAT (a popular implementation of DDA). We present the comparison results and discuss details. Our intent is to release the combined ECBM & IITM+SOV software to the community under an open source license.
A Novel Quasi-3D Method for Cascade Flow Considering Axial Velocity Density Ratio
Chen, Zhiqiang; Zhou, Ming; Xu, Quanyong; Huang, Xudong
2018-03-01
A novel quasi-3D Computational Fluid Dynamics (CFD) method of mid-span flow simulation for compressor cascades is proposed. Two dimension (2D) Reynolds-Averaged Navier-Stokes (RANS) method is shown facing challenge in predicting mid-span flow with a unity Axial Velocity Density Ratio (AVDR). Three dimension (3D) RANS solution also shows distinct discrepancies if the AVDR is not predicted correctly. In this paper, 2D and 3D CFD results discrepancies are analyzed and a novel quasi-3D CFD method is proposed. The new quasi-3D model is derived by reducing 3D RANS Finite Volume Method (FVM) discretization over a one-spanwise-layer structured mesh cell. The sidewall effect is considered by two parts. The first part is explicit interface fluxes of mass, momentum and energy as well as turbulence. The second part is a cell boundary scaling factor representing sidewall boundary layer contraction. The performance of the novel quasi-3D method is validated on mid-span pressure distribution, pressure loss and shock prediction of two typical cascades. The results show good agreement with the experiment data on cascade SJ301-20 and cascade AC6-10 at all test condition. The proposed quasi-3D method shows superior accuracy over traditional 2D RANS method and 3D RANS method in performance prediction of compressor cascade.
Akulov, Y A
2002-01-01
Data on the chemical shifts of half-lives for atomic and molecular tritium were used to determine the ratio of axial-vector-to-vector weak coupling constants for beta decay of triton (G sub A /G sub V) sub t = -1.2646 +- 0.0035
Nagaike, Hayato; Okuizumi, Hiroyuki; Konishi, Yasufumi; Sawada, Hideo; Nonomura, Taku; Asai, Keisuke
2017-11-01
In this study, aerodynamic characteristics of axial circular cylinders having the fineness ratio (length to diameter, L / D) of 0.50, 0.67 and 0.75 were measured using the 1-m Magnetic Suspension and Balance System (MSBS) in the Low-Turbulence Wind Tunnel at Tohoku Univ. The MSBS supports and controls the model using magnetic forces. All the tests were conducted at Re = 100,000 and the models were aligned with the free stream. The results of force measurements show that the drag decreases gradually in the L / D range from 0.50 to 0.75 and connects continuously to the data for higher fineness ratios. This indicates that a local maximum of the drag does not exist in this range. The previous studies show that, for axial circular cylinders having L / D from 1.0 to 2.0, the drag measured using a MSBS differs substantially from the value measured with sting support, however this study shows that a circular cylinder of L / D = 0.50 has a drag close to that measured with sting support. This suggests that the influence of support interference is significant when a shear layer separated from the leading edge reattaches on the body or interacts near the base, but is insignificant when a separated shear layer is away from the base area.
Wang, Hao; Cheng, Weimin; Sun, Biao; Yu, Haiming; Jin, Hu
2018-03-01
To understand the impacts of the axial-to-radial airflow quantity ratio (denoted as R) and the suction distance (denoted as D s ) on air curtain dust control in a fully mechanized coal face, the 3 down 610 coal face in Jiangzhuang coal mine was numerically simulated in this study. A mathematic model was established to describe the airflow migration and dust diffusion in a coal face, and a scaled physical model was constructed. The comparison between simulation results and field measurements validated the model and the parameter settings. Furthermore, the airflow migration and dust diffusion at various R and D s are analyzed using Ansys CFD. The results show that a reduction of R and D s is conducive to the formation of an effective axial dust control air curtain; the dust diffusion distance decreases with the decrease of both R and D s . By analyzing the simulation results, the optimal parameter for air curtain dust control in the 3 down 610 coal face and those faces with similar production conditions is determined as R = 1/9 and D s = 2 m. Under the optimal parameter condition, the high-concentration dust can be confined in front of the mining driver within a space 5.8 m away from the coal face.
Nguyen, Ha Son; Patel, Mohit; Li, Luyuan; Kurpad, Shekar; Mueller, Wade
2017-02-01
Background Diminishing volume of intracranial cerebrospinal fluid (CSF) in patients with space-occupying masses have been attributed to unfavorable outcome associated with reduction of cerebral perfusion pressure and subsequent brain ischemia. Objective The objective of this article is to employ a ratio of CSF volume to brain volume for longitudinal assessment of space-volume relationships in patients with extra-axial hematoma and to determine variability of the ratio among patients with different types and stages of hematoma. Patients and methods In our retrospective study, we reviewed 113 patients with surgical extra-axial hematomas. We included 28 patients (age 61.7 +/- 17.7 years; 19 males, nine females) with an acute epidural hematoma (EDH) ( n = 5) and subacute/chronic subdural hematoma (SDH) ( n = 23). We excluded 85 patients, in order, due to acute SDH ( n = 76), concurrent intraparenchymal pathology ( n = 6), and bilateral pathology ( n = 3). Noncontrast CT images of the head were obtained using a CT scanner (2004 GE LightSpeed VCT CT system, tube voltage 140 kVp, tube current 310 mA, 5 mm section thickness) preoperatively, postoperatively (3.8 ± 5.8 hours from surgery), and at follow-up clinic visit (48.2 ± 27.7 days after surgery). Each CT scan was loaded into an OsiriX (Pixmeo, Switzerland) workstation to segment pixels based on radiodensity properties measured in Hounsfield units (HU). Based on HU values from -30 to 100, brain, CSF spaces, vascular structures, hematoma, and/or postsurgical fluid were segregated from bony structures, and subsequently hematoma and/or postsurgical fluid were manually selected and removed from the images. The remaining images represented overall brain volume-containing only CSF spaces, vascular structures, and brain parenchyma. Thereafter, the ratio between the total number of voxels representing CSF volume (based on values between 0 and 15 HU) to the total number of voxels
Directory of Open Access Journals (Sweden)
N. Sitaram
2011-01-01
Full Text Available The flow field at the rotor exit of a low aspect ratio axial flow fan for different tip geometries and for different flow coefficients is measured in the present study. The following configurations are tested: (1 rotor without partial shroud, designated as rotor (wos, (2 rotor with partial shroud, designated as rotor (ws, and (3 rotor with perforated (perforations in the shape of discrete circular holes partial shroud, designated as rotor (wps. From steady state measurements, the performance of rotor (wps is found to be the best. Both the rotors with partial shrouds have stalled at a higher flow coefficient compared to that of rotor (wos. From periodic flow measurements, it is concluded that the low velocity region near the tip section is considerably reduced with the use of partial shrouds with perforations. The extent of this low velocity region for both rotor (wos and rotor (wps increases with decreasing flow coefficient due to increased stage loading. This core of low momentum fluid has moved inwards of the annulus and towards the pressure side as the flow coefficient decreases. The extent of the low momentum fluid is smaller for rotor (wps than that of rotor (wos at all flow coefficients.
Sabry, Hanan
2014-05-01
Solar screens are typically used to control solar access into building spaces. They proved their usefulness in improving the daylighting and energy performance of buildings in the hot arid desert environments which are endowed with abundance of clear skies.The daylighting and energy performance of solar screens is affected by many parameters. These include screen perforation, depth, reflectivity and color, aspect ratio of openings, shape, tilt angle and rotation. Changing some of these parameters can improve the daylighting performance drastically. However, this can result in increased energy consumption. A balanced solution must be sought, where acceptable daylighting performance would be achieved at minimum energy consumption.This paper aims at defining solar screen designs that achieve visual comfort and at the same time minimum energy consumption in residential desert settings. The study focused on the effect of changing the solar screen axial rotation and the aspect ratio of its openings under the desert clear-sky. The individual and combined effects of changing these parameters were studied.Results of this study demonstrated that a non-rotated solar screen that has wide horizontal openings (aspect ratio of 18:1) proved to be successful in the north and south orientations. Its performance in the east/west orientations was also superior. In contrast, the screen that was rotated along its vertical axis while having small size openings (aspect ratio of 1:1) proved to be more successful in the east/west orientations. Its performance in the north orientation was also good. These solutions enhanced daylighting performance, while maintaining the energy consumption at a minimum.Moreover, it was observed that combining two screen parameters which proved useful in previous studies on daylighting or thermal performance does not add up to better solutions. The combined solutions that were tested in this study did not prove successful in satisfying daylighting and thermal
DEFF Research Database (Denmark)
Witting, Nanna; Andersen, Linda K; Vissing, John
2016-01-01
Classically, myopathies are categorized according to limb or cranial nerve muscle affection, but with the growing use of magnetic resonance imaging it has become evident that many well-known myopathies have significant involvement of the axial musculature. New disease entities with selective axial...
Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.
2014-12-01
Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.
Sieper, Joachim; Braun, Jürgen; Dougados, Maxime; Baeten, Dominique
2015-07-09
The term axial spondyloarthritis covers both non-radiographic disease and radiographic disease (also known as ankylosing spondylitis). Some studies have been performed to investigate the prevalence of axial spondyloarthritis, although most are limited to patients with radiographic disease. A strong genetic association has been shown between axial spondyloarthritis and human leukocyte antigen-B27 (HLA-B27), but the pathogenetic role of HLA-B27 has not yet been clarified. Tumour necrosis factor (TNF), IL-17, IL-23 and downstream pathways also seem to be important - based on the good results of therapies directed against these molecules - but their exact role in the inflammatory process is also not yet clear. Elucidating the interaction between osteoproliferation and inflammation will be crucial for the prevention of long-term structural damage of the bone. The development of new criteria for classification, diagnosis and screening of patients with axial spondyloarthritis will enable earlier intervention for this chronic inflammatory disease. MRI has become an important tool for the early detection of axial spondyloarthritis. NSAIDs and TNF blockers are effective therapies, including in the early non-radiographic stage. Therapeutic blockade of IL-17 or IL-23 seems to be a promising new treatment option. Tools for measuring quality of life in axial spondyloarthritis have become relevant to assess the impact that the disease has on patients. These diagnostic and therapeutic advances will continue to change the management of axial spondyloarthritis, and new insights into the disease pathogenesis will hopefully accelerate this process. For an illustrated summary of this Primer, visit: http://go.nature.com/51b1af.
Chen, Kan; Pang, Cheng-Qun; Liu, Xiang; Matsuki, Takayuki
2015-04-01
Inspired by the abundant experimental observation of axial-vector states, we study whether the observed axial-vector states can be categorized into the conventional axial-vector meson family. In this paper we carry out an analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial-vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial-vector mesons, which are valuable for further experimental exploration of the observed and predicted axial-vector mesons.
Two pad axially grooved hydrostatic bearing
San Andres, Luis A. (Inventor)
1995-01-01
A hydrostatic bearing having two axial grooves on opposite sides of the bearing for breaking the rotational symmetry in the dynamic force coefficients thus reducing the whirl frequency ratio and increasing the damping and stiffness of the hydrostatic bearing.
Sandrock, H.E.
1982-05-06
Static axial mixing apparatus includes a plurality of channels, forming flow paths of different dimensions. The axial mixer includes a flow adjusting device for adjustable selective control of flow resistance of various flow paths in order to provide substantially identical flows through the various channels, thereby reducing nonuniform coating of interior surfaces of the channels. The flow adjusting device may include diaphragm valves, and may further include a pressure regulating system therefor.
International Nuclear Information System (INIS)
1976-01-01
An axial tomographic system is described comprising axial tomographic means for collecting sets of data corresponding to the transmission or absorption of a number of beams of penetrating radiation through a planar slice of an object. It includes means to locate an object to be analyzed, a source and detector for directing one or more beams of penetrating radiation through the object from the source to the detector, and means to rotate (and optionally translate) the source as well as means to process the collected sets of data. Data collection, data processing, and data display can each be conducted independently of each other. An additional advantage of the system described is that the raw data (i.e., the originally collected data) are not destroyed by the data processing but instead are retained intact for further reference or use, if needed
Compton backscattering axial spectrometer
International Nuclear Information System (INIS)
Rad'ko, V.E.; Mokrushin, A.D.; Razumovskaya, I.V.
1981-01-01
Compton gamma backscattering axial spectrometer of new design with the 200 time larger aperture as compared with the known spectrometers at the equal angular resolution (at E=159 keV) is described. Collimator unit, radiation source and gamma detector are located in the central part of the spectrometer. The investigated specimen (of cylindrical form) and the so called ''black body'' used for absorption of photons, passed through the specimen are placed in the peripheric part. Both these parts have an imaginary symmetry axis that is why the spectrometer is called axial. 57 Co is used as the gamma source. The 122 keV spectral line which corresponds to the 83 keV backscattered photon serves as working line. Germanium disk detector of 10 mm diameter and 4 mm height has energy resolution not worse than 900 eV. The analysis of results of test measurements of compton water profile and their comparison with data obtained earlier show that only finity of detector resolution can essentially affect the form of Compton profile. It is concluded that the suggested variant of the spectrometer would be useful for determination of Compton profiles of chemical compounds of heavy elements [ru
Axial skeletal CT densitometry
International Nuclear Information System (INIS)
Lampmann, L.E.H.
1982-01-01
Since the discovery of the Roentgen ray a precise and accurate assessment of bone mineral content has been a challenge to many investigators. A number of methods have been developed but no one satisfied. Considering its technical possibilities computed tomography is very promising in determination of bone mineral content (BMC). The new modality enables BMC estimations in the axial skeletal trabecular bone. CT densitometry can be performed on a normal commercially available third generation whole body CT scanner. No dedicated device in a special clinical set-up is necessary. In this study 106 patients, most of them clinically suspected of osteoporosis, were examined. The new method CT densitometry has been evaluated. The results have been correlated to alternative BMC determination methods. (Auth.)
Notari, Alessio
2016-12-22
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...
Characterization of Multiflux Axial Compressors
International Nuclear Information System (INIS)
Brasnarof, Daniel; Kyung Kyu-Hyung; Rivarola, Martin; Gonzalez Jose; Florido, Pablo; Orellano, Pablo; Bergallo, Juan
2003-01-01
In the present work the results of analytical models of performance are compared with experimental data acquired in the multi flux axial compressor test facility, built in The Pilcaniyeu Technological Complex for the SIGMA project.We describe the experimental circuit and the data of the dispersion inside the axial compressor obtained using a tracer gas through one of the annular inlets.The attained results can be used to validate the design code for the multi flux axial compressors and SIGMA industrial plant
Fluorescence axial nanotomography with plasmonics.
Cade, Nicholas I; Fruhwirth, Gilbert O; Krasavin, Alexey V; Ng, Tony; Richards, David
2015-01-01
We present a novel imaging technique with super-resolution axial sensitivity, exploiting the changes in fluorescence lifetime above a plasmonic substrate. Using conventional confocal fluorescence lifetime imaging, we show that it is possible to deliver down to 6 nm axial position sensitivity of fluorophores in whole biological cell imaging. We employ this technique to map the topography of the cellular membrane, and demonstrate its application in an investigation of receptor-mediated endocytosis in carcinoma cells.
Water ingestion into jet engine axial compressors
Tsuchiya, T.; Murthy, S. N. B.
1982-01-01
An axial flow compressor has been tested with water droplet ingestion under a variety of conditions. The results illustrate the manner in which the compressor pressure ratio, efficiency and surging characteristics are affected. A model for estimating the performance of a compressor during water ingestion has been developed and the predictions obtained compare favorably with the test results. It is then shown that with respect to five droplet-associated nonlinearly-interacting processes (namely, droplet-blade interactions, blade performance changes, centrifugal action, heat and mass transfer processes and droplet break-up), the initial water content and centrifugal action play the most dominant roles.
An electrostatic lower stator axial-gap polysilicon wobble motor part I: Design and modeling
Legtenberg, R.; Legtenberg, Rob; Berenschot, Johan W.; van Baar, J.J.J.; Elwenspoek, Michael Curt
This paper presents design issues and a theoretical model of electrostatically driven axial-gap polysilicon wobble motors. The motor design benefits from large axial rotor-to-stator overlap and large gear ratios, and motor designs with rotor radii of 50 and 100 μm are capable of generating torques
Axial structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner
2002-01-01
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.
Axial stability of Taylor bubbles
Lu, X.; Prosperetti, Andrea
2006-01-01
Long gas bubbles rising in a vertical tube are observed to lose axial symmetry and become unstable in a downward liquid flow. In this paper an approximate linear stability analysis of this phenomenon is presented. It is found that, under the combined effect of gravity and the pressure gradient which
Axial magnetic field produced by axially and radially magnetized permanent rings
International Nuclear Information System (INIS)
Peng, Q.L.; McMurry, S.M.; Coey, J.M.D.
2004-01-01
Axial magnetic fields produced by axially and radially magnetized permanent magnet rings were studied. First, the axial magnetic field produced by a current loop is introduced, from which the axial field generated by an infinitely thin solenoid and by an infinitely thin current disk can be derived. Then the axial fields produced by axially and by radially magnetized permanent magnet rings can be obtained. An analytic formula for the axial fields produced by two axially magnetized rings is given. A permanent magnet with a high axial gradient field is fabricated, the measured results agree with the theoretical calculation very well. As an example, the axial periodic field produced by an arrangement of alternating axially and radially magnetized rings has been discussed
View of the Axial Field Spectrometer
1980-01-01
The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.
International Nuclear Information System (INIS)
Krey, P.W.; Toonkel, L.E.
1977-01-01
Total 90 Sr fallout is adjusted for dry deposition, and scavenging ratios are calculated at Seattle, New York, and Fayetteville, Ark. Stable-lead scavenging ratios are also presented for New York. These ratios show large scatter, but average values are generally inversely proportional to precipitation. Stable-lead ratios decrease more rapidly with precipitation than do those of 90 Sr, a decrease reflecting a lesser availability of lead to the scavenging processes
Indian Academy of Sciences (India)
Our attraction to another body increases if the body is symmetricaland in proportion. If a face or a structure is in proportion,we are more likely to notice it and find it beautiful.The universal ratio of beauty is the 'Golden Ratio', found inmany structures. This ratio comes from Fibonacci numbers.In this article, we explore this ...
Simulations of axial B-dot monitors inside a groove in the beam pipe
Energy Technology Data Exchange (ETDEWEB)
He, Xiaozhong, E-mail: hexiaozhong@tsinghua.org.cn [Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang, Sichuan (China); Pang, Jian; Li, Qin [Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang, Sichuan (China); Du, Yingchao [Department of Engineering Physics, Tsinghua University, Beijing (China)
2013-11-21
Beam tilt measurement is important for understanding the beam dynamics. Our previous theoretical studies and simulations have shown that the axial B-dot in smooth beam pipe can be used to measure the beam tilt directly. Practical azimuthal B-dot loops typically are placed inside a groove in the beam pipe to avoid direct beam interception. For the same purpose, practical axial B-dot loops should also be placed inside such a groove. In this paper, responses of axial magnetic field to the beam tilt and to the beam offset, in the presence of the groove, are investigated by simulations. The simulation results show that the axial magnetic field in the central plane of the groove is proportional to the beam tilt and independent on the centroid position. The ratio between the axial magnetic field and the beam tilt depends on the position of the axial B-dot loop and the dimensions of the groove. -- Highlights: •MAFIA simulations were carried out to analyze the influence of recessed groove to axial B dots. •It is found that axial B dots still works in the central plane of the recessed groove. •The dimensions of the groove greatly influence the signal strength of axial B dots. •Results can be used for future optimizations.
Cyclic Axial-Torsional Deformation Behavior of a Cobalt-Base Superalloy
Bonacuse, Peter J.; Kalluri, Sreeramesh
1995-01-01
The cyclic, high-temperature deformation behavior of a wrought cobalt-base super-alloy, Haynes 188, is investigated under combined axial and torsional loads. This is accomplished through the examination of hysteresis loops generated from a biaxial fatigue test program. A high-temperature axial, torsional, and combined axial-torsional fatigue database has been generated on Haynes 188 at 760 C. Cyclic loading tests have been conducted on uniform gage section tubular specimens in a servohydraulic axial-torsional test rig. Test control and data acquisition were accomplished with a minicomputer. The fatigue behavior of Haynes 188 at 760 C under axial, torsional, and combined axial-torsional loads and the monotonic and cyclic deformation behaviors under axial and torsional loads have been previously reported. In this paper, the cyclic hardening characteristics and typical hysteresis loops in the axial stress versus axial strain, shear stress ,versus engineering shear strain, axial strain versus engineering shear strain. and axial stress versus shear stress spaces are presented for cyclic in-phase and out-of-phase axial-torsional tests. For in-phase tests, three different values of the proportionality constant lambda (the ratio of engineering shear strain amplitude to axial strain amplitude, are examined, viz. 0.86, 1.73, and 3.46. In the out-of-phase tests, three different values of the phase angle, phi (between the axial and engineering shear strain waveforms), are studied, viz., 30, 60, and 90 degrees with lambda equals 1.73. The cyclic hardening behaviors of all the tests conducted on Haynes 188 at 760 C are evaluated using the von Mises equivalent stress-strain and the maximum shear stress-maximum engineering shear strain (Tresca) curves. Comparisons are also made between the hardening behaviors of cyclic axial, torsional, and combined in-phase (lambda = 1.73 and phi = 0) and out-of-phase (lambda = 1.73 and phi = 90') axial-torsional fatigue tests. These comparisons
Axial diagnostic package for Z
International Nuclear Information System (INIS)
Nash, T.J.; Derzon, M.S.; Chandler, G.
1998-06-01
The authors have developed and fielded an axial diagnostic package for the 20 MA, 100 ns, z-pinch driver Z. The package is used to diagnose dynamic hohlraum experiments which require an axial line of sight. The heart of the package is a reentrant cone originally used to diagnose ion-beam-driven hohlraums on PBFA-H. It has one diagnostic line of sight at 0 degrees, 4 at 6 degrees, and 4 at 9 degrees. In addition it has a number of viewing, alignment, and vacuum feedthrough ports. The front of the package sits approximately 5 feet from the pinch. This allows much closer proximity to the pinch, with inherently better resolution and signal, than is presently possible in viewing the pinch from the side. Debris that is preferentially directed along the axis is mitigated by two apertures for each line of sight, and by fast valves and imaging pinholes or cross slits for each diagnostic. In the initial run with this package they fielded a time resolved pinhole camera, a five-channel pinhole-apertured x-ray diode array, a bolometer, a spatially resolved time-integrated crystal spectrometer, and a spatially and temporally resolved crystal spectrometer. They present data obtained from these diagnostics in the dynamic hohlraum research conducted on Z
Channel of Axial Injection of DC-60 Cyclotron
Gikal, B N; Bogomolov, S L; Borisenko, A N; Borisov, O N; Gulbekyan, G G; Ivanenko, I A; Kalagin, I V; Kazacha, V I; Kazarinov, N Yu; Khabarov, M V; Lysukhin, S N; Melnikov, V N; Paschenko, S V; Tikhomirov, A V
2006-01-01
The design study and realization of the axial injection beam line of DC-60 cyclotron constructed at the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research are given. The channel allows one to transport and to inject into the cyclotron ions with mass-to-charge ratio $A/Z$ being within interval A/Z=6-12 and kinetic energy up to 17 $Z/A$ keV/m.u.
Energy Technology Data Exchange (ETDEWEB)
Pang, Xiaoping; Chen, Jin; Hussain, Sinan H [Chongqung University, Chongqing (China)
2013-12-15
This paper is focused on using GA genetic algorithm to find the optimal performance with respect to shape optimization in three dimensions for the hydrodynamic journal bearing. The mathematical model for film thickness was drawn using Fourier series function and axial waviness value (Δ) D to represent the journal bearing in circumferential and axial direction, respectively. The objective was then to determine the Fourier coefficients and axial waviness value (Δ) D that maximized the load capacity subjected to a given set of constraint. Optimized results show that the presence of cos wave in axial direction, with a positive dimensionless amplitude (+A) and waviness number m = 0.633, improves the load capacity by (8-10) % over the cylindrical plain bearing with the same arbitrary shape and size; in general, the increasing order of Fourier series (n), an axial dimensionless amplitude and L/D ratio cause the change in load capacity to become more evident.
Elevated temperature axial and torsional fatigue behavior of Haynes 188
Bonacuse, Peter J.; Kalluri, Sreeramesh
1995-01-01
The results are reported for high-temperature axial and torsional low-cycle fatigue experiments performed at 760 C in air on thin-walled tubular specimens of Haynes 188, a wrought cobalt-based superalloy. Data are also presented for mean coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. This data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME Boiler and Pressure Code), Manson-Halford, modified multiaxiality factor (proposed in this paper), modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The modified multiaxiality factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.
Electric machines with axial magnetic flux
Nuca, I.; Ambros, T.; Burduniuc, M.; Deaconu, S. I.; Turcanu, A.
2018-01-01
The paper contains information on the performance of axial machines compared to cylindrical ones. At the same time, various constructive schemes of synchronous electromechanical converters with permanent magnets and asynchronous with short-circuited rotor are presented. In the developed constructions, the aim is to maximize the usage of the material of the stator windings. The design elements of the axial machine magnetic system are presented. The FEMM application depicted the array of the magnetic field of an axial machine.
Axial vector mass spectrum and mixing angles
International Nuclear Information System (INIS)
Caffarelli, R.V.; Kang, K.
1976-01-01
Spectral sum rules of the axial-vector current and axial-vector current-pseudoscalar field are used to study the axial-vector mass spectrum and mixing angles, as well as the decay constants and mixing angles of the pseudoscalar mesons. In general, the result is quite persuasive for the existence of the Jsup(PC) = 1 ++ multiplet in which one has a canonical D-E mixing. (Auth.)
Centrifugal and axial compressor control
McMillan, Gregory K
2009-01-01
Control engineers, mechanical engineers and mechanical technicians will learn how to select the proper control systems for axial and centrifugal compressors for proper throughput and surge control, with a particular emphasis on surge control. Readers will learn to understand the importance of transmitter speed, digital controller sample time, and control valve stroking time in helping to prevent surge. Engineers and technicians will find this book to be a highly valuable guide on compressor control schemes and the importance of mitigating costly and sometimes catastrophic surge problems. It can be used as a self-tutorial guide or in the classroom with the book's helpful end-of-chapter questions and exercises and sections for keeping notes.
Axial channeling of uttrarelativistic electrons
Energy Technology Data Exchange (ETDEWEB)
Telegin, V.I.; Khokonov, M.Kh. (Moskovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Yadernoj Fiziki)
1982-07-01
The dynamics of motion of ultrarelativistic electrons under axial channeling conditions is investigated. The analysis is based on the solution of the kinetic equation obtained recently by Beloshitsky and Kumakhov. The particle dechanneling function is investigated as depending on the type of a crystal, particle energy and angle of entrance into the single crystal. It is found that for most of the beam the major diffusion mechanism is scattering by electrons. It is shown that an optimal depth range exists for which the fraction of channeled particles sharply increases at the expense of the quasi-channeled particles. In a number of cases the dechanneling length for crystals with high atomic numbers may be greater than that of light elements.
Axial channeling of uttrarelativistic electrons
International Nuclear Information System (INIS)
Telegin, V.I.; Khokonov, M.Kh.
1982-01-01
The dynamics of motion of ultrarelativistic electrons under axial channeling conditions is investigated. The analysis is based on the solution of the kinetic equation obtained recently by Beloshitsky and Kumakhov. The particle dechanneling function is investigated as depending on the type of a crystal, particle energy and angle of entrance into the single crystal. It is found that for most of the beam the major diffusion mechanism is scattering by electrons. It is shown that an optimal depth range exists for which the fraction of channeled particles sharply increases at the expense of the quasi-channeled particles. In a number of cases the dechanneling length for crystals with high atomic numbers may be greater than that of light elements
Radial and axial compression of pure electron
International Nuclear Information System (INIS)
Park, Y.; Soga, Y.; Mihara, Y.; Takeda, M.; Kamada, K.
2013-01-01
Experimental studies are carried out on compression of the density distribution of a pure electron plasma confined in a Malmberg-Penning Trap in Kanazawa University. More than six times increase of the on-axis density is observed under application of an external rotating electric field that couples to low-order Trivelpiece-Gould modes. Axial compression of the density distribution with the axial length of a factor of two is achieved by controlling the confining potential at both ends of the plasma. Substantial increase of the axial kinetic energy is observed during the axial compression. (author)
Axial and Radial Oxylipin Transport.
Gasperini, Debora; Chauvin, Adeline; Acosta, Ivan F; Kurenda, Andrzej; Stolz, Stéphanie; Chételat, Aurore; Wolfender, Jean-Luc; Farmer, Edward E
2015-11-01
Jasmonates are oxygenated lipids (oxylipins) that control defense gene expression in response to cell damage in plants. How mobile are these potent mediators within tissues? Exploiting a series of 13-lipoxygenase (13-lox) mutants in Arabidopsis (Arabidopsis thaliana) that displays impaired jasmonic acid (JA) synthesis in specific cell types and using JA-inducible reporters, we mapped the extent of the transport of endogenous jasmonates across the plant vegetative growth phase. In seedlings, we found that jasmonate (or JA precursors) could translocate axially from wounded shoots to unwounded roots in a LOX2-dependent manner. Grafting experiments with the wild type and JA-deficient mutants confirmed shoot-to-root oxylipin transport. Next, we used rosettes to investigate radial cell-to-cell transport of jasmonates. After finding that the LOX6 protein localized to xylem contact cells was not wound inducible, we used the lox234 triple mutant to genetically isolate LOX6 as the only JA precursor-producing LOX in the plant. When a leaf of this mutant was wounded, the JA reporter gene was expressed in distal leaves. Leaf sectioning showed that JA reporter expression extended from contact cells throughout the vascular bundle and into extravascular cells, revealing a radial movement of jasmonates. Our results add a crucial element to a growing picture of how the distal wound response is regulated in rosettes, showing that both axial (shoot-to-root) and radial (cell-to-cell) transport of oxylipins plays a major role in the wound response. The strategies developed herein provide unique tools with which to identify intercellular jasmonate transport routes. © 2015 American Society of Plant Biologists. All Rights Reserved.
Axial and Pressure Thrust Stiffness of Metal Bellows for Vibration Isolators
Directory of Open Access Journals (Sweden)
Ondřej Macháček
2018-01-01
Full Text Available Metal bellows are used as a spring element and simultaneously as a container (shell for a damping medium in vibration isolators, especially in applications where any leakage is inadmissible. Dynamic behaviour of these isolators is affected by axial stiffness of bellows and by a resistance against axial deformation of bellows filled with fluid, which is in this article called pressure thrust stiffness. A method of the pressure thrust stiffness determination is discussed in this study. The method uses FEM model, which has been verified by stiffness measurement of a chosen bellows. Consequently, the sensitivity analysis of bellows dimensions to axial and pressure thrust stiffness was performed to find a dimension parameter of bellows which allows to adjust the ratio between axial and pressure thrust stiffness. Sensitivity analysis shows that the stiffness ratio of metal bellows can be adjusted by two dimensional parameters - mean diameter of bellows and corrugation width.
Improvements of axial resolution in confocal microscopy with fan-shaped apertures.
Ma, Ye; Kuang, Cuifang; Gong, Wei; Xue, Li; Zheng, Yao; Wang, Yifan; Si, Ke; Liu, Xu
2015-02-20
Based on diffraction theory, this paper theoretically demonstrates improvements in axial resolution in confocal microscopy with fan-shaped apertures. It provides the optimal geometric parameters of the fan-shaped pupils to give the maximum axial resolution for a given pinhole size. To fully understand the overall performance, the signal-to-background ratio and the signal level with regard to the geometric parameters are discussed.
Health and imaging outcomes in axial spondyloarthritis
Machado, P.M.
2016-01-01
This thesis focuses on the assessment and monitoring of health and imaging outcomes in axial spondyloarthritis (SpA) and the relationship between these outcomes. Four major contributions to the understanding and management of axial SpA were made: 1) the improvement and facilitation of the assessment
Aryabhata and Axial Rotation of Earth
Indian Academy of Sciences (India)
GENERAL I ARTICLE. Aryabhata and Axial Rotation of Earth. 3. A Brief History. Amartya Kumar Datta is in the Stat-Math Unit of. Indian Statistic.llnstiutte,. Kolkata. His research ... historical account of some of Aryabha~a's views on axial rotation of Earth, ..... and stress on periodic observations and updating of the parameters.
Axial positrons emission tomography: from mouse to human brain imaging
International Nuclear Information System (INIS)
Brard, Emmanuel
2013-01-01
Positrons emission tomography is a nuclear imaging technics using nuclear decays. It is used both in clinical and preclinical studies. The later requires the use of small animals such as the mouse. The objective is to obtain the best signal with the best spatial resolution. Yet, a weight ratio between humans and mice indicates the need of a sub-millimeter resolution. A conventional scanner is based on detection modules surrounding the object to image and arranged perpendicularly. This implies a strong relationship between efficiency and spatial resolution. This work focuses on the axial geometry in which detection modules are arranged parallel to the object. This limits the relationship between the figures of merit, leading to both high spatial resolution and efficiency. The simulations of prototypes showed great perspectives in term of sub-millimeter resolution with efficiencies of 15 or 40% according to the scanner's axial extension. These results indicate great perspectives for both clinical and preclinical imaging. (author)
Axial Ge/Si nanowire heterostructure tunnel FETs
Energy Technology Data Exchange (ETDEWEB)
Picraux, Sanuel T [Los Alamos National Laboratory; Daych, Shadi A [Los Alamos National Laboratory
2010-01-01
The vapor-liquid-solid (VLS) growth of semiconductor nanowires allows doping and composition modulation along their axis and the realization of axial 1 D heterostructures. This provides additional flexibility in energy band-edge engineering along the transport direction which is difficult to attain by planar materials growth and processing techniques. We report here on the design, growth, fabrication, and characterization of asymmetric heterostructure tunnel field-effect transistors (HTFETs) based on 100% compositionally modulated Si/Ge axial NWs for high on-current operation and low ambipolar transport behavior. We discuss the optimization of band-offsets and Schottky barrier heights for high performance HTFETs and issues surrounding their experimental realization. Our HTFET devices with 10 nm PECVD SiN{sub x} gate dielectric resulted in a measured current drive exceeding 100 {mu}A/{mu}m (I/{pi}D) and 10{sup 5} I{sub on}/I{sub off} ratios.
Indian Academy of Sciences (India)
of mathematical biology. Our attraction to another body increases if the body is sym- metrical and in proportion. If a face or a structure is in pro- ... his practice of oral and maxillofacial surgery, and he developed a mask using the concept of golden ratio. The mask is called the. Marquardt beauty mask (Figure 1) [1]. Keywords.
Axial anomalies of Lifshitz fermions
Bakas, Ioannis
2011-01-01
We compute the axial anomaly of a Lifshitz fermion theory with anisotropic scaling z=3 which is minimally coupled to geometry in 3+1 space-time dimensions. We find that the result is identical to the relativistic case using path integral methods. An independent verification is provided by showing with spectral methods that the eta-invariant of the Dirac and Lifshitz fermion operators in three dimensions are equal. Thus, by the integrated form of the anomaly, the index of the Dirac operator still accounts for the possible breakdown of chiral symmetry in non-relativistic theories of gravity. We apply this framework to the recently constructed gravitational instanton backgrounds of Horava-Lifshitz theory and find that the index is non-zero provided that the space-time foliation admits leaves with harmonic spinors. Using Hitchin's construction of harmonic spinors on Berger spheres, we obtain explicit results for the index of the fermion operator on all such gravitational instanton backgrounds with SU(2)xU(1) isom...
Bone formation in axial spondyloarthritis.
Lories, Rik J; Haroon, Nigil
2014-10-01
The success of targeted therapies directed against tumor necrosis factor for patients with spondyloarthritis has shifted the focus of physicians and scientists towards the prevention of structural damage to the involved structures, in particular the sacroiliac joints and the spine, to avoid loss of function and disability. Structural damage to the skeleton as witnessed by radiography mainly consists of new bone formation potentially progressively leading to spine or joint ankylosis. This important long-term outcome parameter has been difficult to study, not alone because the time window for change may be long but also because human tissues with direct translational relevance are rarely available. Data from rodent models have identified growth factor signaling pathways as relevant targets. Both human and animal studies have tried to understand the link between inflammation and new bone formation. At the current moment, most evidence points towards a strong link between both but with the question still lingering about the sequence of events, disease triggers, and the interdependence of both features of disease. New discoveries such as a masterswitch T cell population that carries the IL23 receptor and the analysis of auto-antibodies directed again noggin and sclerostin are contributing to innovative insights into the pathophysiology of disease. Long-term data with tumor necrosis factor (TNF) inhibitors also suggest that some window of opportunity may exist to inhibit structural disease progression. All these data provide support for a further critical analysis of the available datasets and boost research in the field. The introduction of novel disease definitions, in particular the characterization of non-radiographic axial spondyloarthritis patients, will likely be instrumental in our further understanding of structural damage. Copyright © 2014 Elsevier Ltd. All rights reserved.
Diagnostic value of axial CT scan
Energy Technology Data Exchange (ETDEWEB)
Kiuchi, Sousuke (Tsukuba Univ., Sakura, Ibaraki (Japan))
1983-03-01
Axial CT scan was used to investigate the radiological details of the temporal bone of 33 patients with chronic otitis media, secondary cholesteatoma, sensorineural hearing loss, Meniere disease, vertigo, facial spasm, and neoplasma. The axial scans showed anatomic details of the temporal bone, and at the same time clearly demonstrated the extent of the soft-tissue masses in the middle ears, as well as the destructions of the ossicles. Bone changes of the anterior walls of the epitympanum and external auditory meatus were more clearly demonstrated than by coronary CT scan. However, the axial scan had the disadvantages in demonstrating the stapes, crista transversa, and the mastoid portion of the facial canal.
Axial force measurement for esophageal function testing
DEFF Research Database (Denmark)
Gravesen, Flemming Holbæk; Funch-Jensen, Peter; Gregersen, Hans
2009-01-01
force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external...... documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe...
Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Ariztizabal, F; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Gaitan, V; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Engelhardt, A; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Markou, C; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wiedenmann, W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Bardadin-Otwinowska, Maria; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Saadi, F; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Kyriakis, A; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Passalacqua, L; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Pepé-Altarelli, M; Dorris, S J; Halley, A W; ten Have, I; Knowles, I G; Lynch, J G; Morton, W T; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Smith, M G; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Konstantinidis, N P; Moneta, L; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Raab, J; Renk, B; Sander, H G; Wanke, R; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Thulasidas, M; Nicod, D; Payre, P; Rousseau, D; Talby, M; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wolf, G; Alemany, R; Boucrot, J; Callot, O; Cordier, A; Courault, F; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Musolino, G; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Abbaneo, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Triggiani, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Mir, L M; Perrodo, P; Strong, J A; Bertin, V; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Cartwright, S L; Combley, F; Dawson, I; Köksal, A; Letho, M; Newton, W M; Rankin, C; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G
1996-01-01
From 64492 selected \\tau-pair events, produced at the Z^0 resonance, the measurement of the tau decays into hadrons from a global analysis using 1991, 1992 and 1993 ALEPH data is presented. Special emphasis is given to the reconstruction of photons and \\pi^0's, and the removal of fake photons. A detailed study of the systematics entering the \\pi^0 reconstruction is also given. A complete and consistent set of tau hadronic branching ratios is presented for 18 exclusive modes. Most measurements are more precise than the present world average. The new level of precision reached allows a stringent test of \\tau-\\mu universality in hadronic decays, g_\\tau/g_\\mu \\ = \\ 1.0013 \\ \\pm \\ 0.0095, and the first measurement of the vector and axial-vector contributions to the non-strange hadronic \\tau decay width: R_{\\tau ,V} \\ = \\ 1.788 \\ \\pm \\ 0.025 and R_{\\tau ,A} \\ = \\ 1.694 \\ \\pm \\ 0.027. The ratio (R_{\\tau ,V} - R_{\\tau ,A}) / (R_{\\tau ,V} + R_{\\tau ,A}), equal to (2.7 \\pm 1.3) \\ \\%, is a measure of the importance of Q...
The New Performance Calculation Method of Fouled Axial Flow Compressor
Directory of Open Access Journals (Sweden)
Huadong Yang
2014-01-01
Full Text Available Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds’ law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail.
Experimental study of large scale axially heterogeneous LMFBR core at FCA, (3)
International Nuclear Information System (INIS)
Iijima, Susumu; Okajima, Sigeaki; Sanda, Toshio
1985-04-01
FCA Assembly XII-1 is the second core in axial heterogeneous core experiment program at FCA and is a standard experimental core for the measurements of the axial nuclear characteristics in the axial heterogeneous core. Following nuclear characteristics have been measured, (i) criticality, (ii) sodium void and sample reactivity worths, (iii) reaction rates and ratios, (iv) Doppler reactivity worth, (v) B 4 C control rod worth and (vi) gamma heating. Following the standard core experiment, sample worths and reaction rate distributions has been measured using the assembly with B 4 C control rod at a central region. In order to examin data and method for the calculation of nuclear characteristics of the axial heterogeneous core, experimental analysis has been performed using nuclear data library JENDL-2 and JAERI's nuclear characteristics calculation system for a fast reactor. (author)
Capacitive axial position and speed transduction system
International Nuclear Information System (INIS)
Jimenez D, H.; Flores Ll, H.; Cabral P, A.; Ramirez J, F.J.; Galindo, S.
1984-01-01
A new and inexpensive circuit arrangement of a capacitive axial position and speed transduction system is described. Design details and the theory of operation of the device are briefly outlined together with performance results. (author)
High temperature co-axial winding transformers
Divan, Deepakraj M.; Novotny, Donald W.
1993-01-01
The analysis and design of co-axial winding transformers is presented. The design equations are derived and the different design approaches are discussed. One of the most important features of co-axial winding transformers is the fact that the leakage inductance is well controlled and can be made low. This is not the case in conventional winding transformers. In addition, the power density of co-axial winding transformers is higher than conventional ones. Hence, using co-axial winding transformers in a certain converter topology improves the power density of the converter. The design methodology used in meeting the proposed specifications of the co-axial winding transformer specifications are presented and discussed. The final transformer design was constructed in the lab. Co-axial winding transformers proved to be a good choice for high power density and high frequency applications. They have a more predictable performance compared with conventional transformers. In addition, the leakage inductance of the transformer can be controlled easily to suit a specific application. For space applications, one major concern is the extraction of heat from power apparatus to prevent excessive heating and hence damaging of these units. Because of the vacuum environment, the only way to extract heat is by using a cold plate. One advantage of co-axial winding transformers is that the surface area available to extract heat from is very large compared to conventional transformers. This stems from the unique structure of the co-axial transformer where the whole core surface area is exposed and can be utilized for cooling effectively. This is a crucial issue here since most of the losses are core losses.
Axial model in curved space-time
Energy Technology Data Exchange (ETDEWEB)
Barcelos-Neto, J.; Farina, C.; Vaidya, A.N.
1986-12-11
We study the axial model in a background gravitational field. Using the zeta-function regularization, we obtain explicitly the anomalous divergence of the axial-vector current and the exact generating functional of the theory. We show that, as a consequence of a space-time-dependent metric, all differential equations involved in the theory generalize to their covariantized forms. We also comment on the finite-mass renormalization exhibited by the pseudoscalar field and the form of the fermion propagator.
Dechanneling function for relativistic axially channeled electrons
International Nuclear Information System (INIS)
Muralev, V.A.; Telegin, V.I.
1981-01-01
Behaviour of the x(t) dechanneling function depending on the depth is theoretically studied. Theoretical consideration of x(t) for axial channeled relativistic electrons in anisotropic medium results in two-dimensional kinetic equation with mixed derivatives of the parabolic type. The kinetic equation in the approximation of the continuous Lindchard model for relativistic axial channeled electrons is numerically solved. The depth dependence of the x(t) dechanneling function is obtained [ru
Axial forces in centrifugal compressor couplings
Ivanov, A. N.; Ivanov, N. M.; Yun, V. K.
2017-08-01
The article presents the results of the theoretical and experimental investigation of axial forces arising in the toothed and plate couplings of centrifugal compressor shaft lines. Additional loads on the thrust bearing are considered that can develop in the toothed couplings as a result of coupled rotors misalignment. Design relationships to evaluate the level of axial forces and recommendations for their reduction in the operating conditions are given.
High harmonic generation from axial chiral molecules.
Wang, Dian; Zhu, Xiaosong; Liu, Xi; Li, Liang; Zhang, Xiaofan; Lan, Pengfei; Lu, Peixiang
2017-09-18
Axial chiral molecules, whose stereogenic element is an axis rather than a chiral center, have attracted widespread interest due to their important application, such as asymmetric synthesis and chirality transfer. We investigate high harmonic generation from axial chiral molecules with bichromatic counterrotating circularly polarized laser fields. High harmonic generation from three typical molecules: (Sa)-3-chloropropa-1,2-dien-1-ol, propadiene, and (Ra)-2,3-pentadiene is simulated with time-dependent density-functional theory and strong field approximation. We found that harmonic spectra for 3D oriented axial chiral molecules exhibit obvious circular dichroism. However, the circular dichroism of High harmonic generation from an achiral molecule is much trivial. Moreover, the dichroism of high harmonic generation still exists when axial chiral molecules are 1D oriented,such as (Sa) -3-chloropropa-1,2-dien-1-ol. For a special form of axial chiral molecules with the formula abC=C=Cab (a, b are different substituents), like (Ra)-2,3-pentadiene, the dichroism discriminations disappear when the molecules are only in 1D orientation. The circular dichroism of high harmonic generation from axial chiral molecules is well explained by the trajectory analysis based on the semiclassical three-step mechanism.
Directory of Open Access Journals (Sweden)
Chayanon Hansapinyo
2003-01-01
Full Text Available This paper presents the experimental investigation on the failure mechanism and ultimate capacity of rectangular reinforced concrete beam under combined action of bi-axial shear accompanied with torsion through the test of four reinforced concrete members. The simple experimental set-up for a simply-supported beam under one point loading is introduced in this study by applying eccentric load to the tilted beam. This requires only one hydraulic jack to produce the complicated bi-axial shear and torsional loading. The main parameter is the magnitude of torsion induced to specimens which is relatively represented by the torsion-to-shear ratio. In addition, the influence of torsion on ultimate capacity of reinforced concrete with different ratio of two shears is investigated. From the experimental results, it is found that the increase in the magnitude of torsion about 69 percent drastically decreases bi-axial shear capacity as much as 12 to 39 percent according to the ratio of bi-axial shears. The experimental results are compared with the capacities calculated by the available interaction formula between uni-axial shear and torsion in the current design codes. The comparison indicates that the current design codes give quite conservative values of ultimate capacity.
Renormalization of the axial-vector current in QCD
International Nuclear Information System (INIS)
Chiu, C.B.; Pasupathy, J.; Wilson, S.L.
1985-01-01
Following the method of Ioffe and Smilga, the propagation of the baryon current in an external constant axial-vector field is considered. The close similarity of the operator-product expansion with and without an external field is shown to arise from the chiral invariance of gauge interactions in perturbation theory. Several sum rules corresponding to various invariants both for the nucleon and the hyperons are derived. The analysis of the sum rules is carried out by two independent methods, one called the ratio method and the other called the continuum method, paying special attention to the nondiagonal transitions induced by the external field between the ground state and excited states. Up to operators of dimension six, two new external-field-induced vacuum expectation values enter the calculations. Previous work determining these expectation values from PCAC (partial conservation of axial-vector current) are utilized. Our determination from the sum rules of the nucleon axial-vector renormalization constant G/sub A/, as well as the Cabibbo coupling constants in the SU 3 -symmetric limit (m/sub s/ = 0), is in reasonable accord with the experimental values. Uncertainties in the analysis are pointed out. The case of broken flavor SU 3 symmetry is also considered. While in the ratio method, the results are stable for variation of the fiducial interval of the Borel mass parameter over which the left-hand side and the right-hand side of the sum rules are matched, in the continuum method the results are less stable. Another set of sum rules determines the value of the linear combination 7F-5D to be roughly-equal0, or D/(F+D)roughly-equal(7/12). .AE
Vector and axial constants of the baryon decuplet
International Nuclear Information System (INIS)
Belyaev, V.M.; Blok, B.Y.; Kogan, Y.I.
1985-01-01
On the basis of the QCD sum rules for the polarization operator in external axial and vector fields we determine the vector and axial transition constants in the 3/2 + baryon decuplet. We show that the renormalization of the axial constant is due to the interaction of the external axial field with the quark condensate
Nucleon axial form factor from lattice QCD
International Nuclear Information System (INIS)
Liu, K.F.; Dong, S.J.; Draper, T.; Wu, J.M.; Wilcox, W.
1994-01-01
Results for the isovector axial form factors of the proton from a lattice QCD calculation are presented for both the point-split and local currents. They are obtained on a quenched 16 3 x24 lattice at β=6.0 with Wilson fermions for a range of quark masses from strange to twice the charm mass. For each quark mass, we find that the axial form factor falls off slower than the corresponding proton electric form factor. Results extrapolated to the chiral limit show that the q 2 dependence of the axial form factor agrees quite well with experiment. The axial vector coupling constant g A calculated for the point-split and local currents is 1.20±0.11 and 1.18±0.11. The central values are 4% and 6% smaller than the experimental value of 1.254, respectively. We also consider the large ma correction and renormalization for the axial vector current of heavy quarks
Optimization of residual heat removal pump axial thrust and axial bearing
International Nuclear Information System (INIS)
Schubert, F.
1996-01-01
The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies
Optimization of residual heat removal pump axial thrust and axial bearing
Energy Technology Data Exchange (ETDEWEB)
Schubert, F.
1996-12-01
The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.
Approach to improve the axial power distribution for the application of a core protection system
International Nuclear Information System (INIS)
Koo, Bon Seung; Cho, Jin Young; Song, Jae Seung; Lee, Chung Chan
2008-01-01
A Core Protection Calculator System (CPCS) is a digital computer based on a safety system for generating trip signals based on a calculation of the Departure from Nucleate Boiling Ratio (DNBR) and the Local Power Density (LPD) by using several on-line measured system parameters including 3-level ex-core detector signals. A few approaches to improve the axial power distribution for the application of a core protection system were performed. For the Yonggwang unit 3 (cycle 1), axial power distributions were synthesized by applying the cubic spline method and compared with the neutronics code results. Several new cubic spline function sets were generated for the drastically distorted axial shapes for a 3-level ex-core detector system. In addition, synthesized axial shapes with a 5-level ex-core detector signals were compared with the conventional 3-level detector results. It demonstrates that the newly generated function sets appear to be better than that of the conventional CPC from the aspect of an axial power synthesis, particularly for the heavily distorted shapes. Moreover, synthesis of an axial power distribution using 5-level ex-core detector signals appears to be better than that of the 3-level ex-core detector signals. From the above results, improvement of the thermal margin is expected because of an uncertainty decreasing a core protection system. (authors)
Wave propagation in axially moving periodic strings
DEFF Research Database (Denmark)
Sorokin, Vladislav S.; Thomsen, Jon Juel
2017-01-01
The paper deals with analytically studying transverse waves propagation in an axially moving string with periodically modulated cross section. The structure effectively models various relevant technological systems, e.g. belts, thread lines, band saws, etc., and, in particular, roller chain drives...... for diesel engines by capturing both their spatial periodicity and axial motion. The Method of Varying Amplitudes is employed in the analysis. It is shown that the compound wave traveling in the axially moving periodic string comprises many components with different frequencies and wavenumbers....... This is in contrast to non-moving periodic structures, for which all components of the corresponding compound wave feature the same frequency. Due to this "multi-frequency" character of the wave motion, the conventional notion of frequency band-gaps appears to be not applicable for the moving periodic strings. Thus...
International Nuclear Information System (INIS)
Reesink, E.M.; Lataster, L.M.A.; Mameren, H. van; Wilmink, J.T.; Kingma, H.
2001-01-01
Deformation of the extradural space and the possibility of impression upon the dural sac during atlanto-axial rotation are investigated. Atlanto-axial rotation leads to a reduction in the cross-sectional area of the bony spinal canal of approximately 40 %. Atlanto-axial rotation was recorded by endocanalar views from a video camera fixed inside the skull of six unembalmed cadavers. Axial thin-section T1-weighted MRI slice sets were acquired from three volunteers (mid-position and maximal left and right rotation of the head and cervical spine). The axial cross-sectional areas of the bony spinal canal, dural sac and spinal cord were measured. In two other persons post-gadolinium contrast-enhanced T1-weighted MRI volume scans with fat-suppression prepulse were acquired (mid-position and rotation) to determine venous contents of the extradural space. The 50:50 ratio between left and right extradural halves in mid-position changed to an ipsilateral:contralateral ratio of 20:80 in maximum rotation at the level just above the lateral C1-C2 joints. Directly below these joints the opposite occurred. The post-contrast studies showed an enhancing internal vertebral venous plexus (IVVP), which almost completely occupied the extradural space at the atlanto-axial level. This could not be shown in the cadaver experiments, because of absence of blood and cerebrospinal fluid (CSF) pressure. During atlanto-axial rotation blood displacement in the IVVP allows major deformations of the extradural space. This prevents dural sac impression. (orig.)
Axial pico turbine - construction and experimental research
Peczkis, G.; Goryca, Z.; Korczak, A.
2017-08-01
The paper concerns axial water turbine of power equal to 1 kW. The example of axial water turbine constructional calculations was provided, as well as turbine rotor construction with NACA profile blades. The laboratory test rig designed and built to perform measurements on pico turbine was described. The turbine drove three-phase electrical generator. On the basis of highest efficiency parameters, pico turbine basic characteristics were elaborated. The experimental research results indicated that pico turbine can achieve maximum efficiency close to the values of larger water turbines.
Axial Vircator for Electronic Warfare Applications
Directory of Open Access Journals (Sweden)
L. Drazan
2009-12-01
Full Text Available This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO, it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.
Characterization of fluid forces exerted on a cylinder array oscillating laterally in axial flow
International Nuclear Information System (INIS)
Divaret, Lise
2014-01-01
This thesis presents an experimental and a numerical study of the fluid forces exerted on a cylinder or a cylinder array oscillating laterally in an axial flow. The parameters of the system are the amplitude, the oscillation frequency, the confinement and the length to diameter ratio of the cylinder. The objective is to determine the fluid damping created by the axial flow, i.e. the dissipative force. The industrial application of this thesis is the determination of the fluid damping of the fuel assemblies in the core of a nuclear power plant during an earthquake. The study focuses on the configurations where the oscillation velocity is small compared to the axial flow velocity. In a first part, we study the case of a cylinder with no confinement oscillating in axial flow. Two methods are used: a dynamical and a quasi-static approach. In dynamics, the damping rate is measured during free oscillations of the cylinder. In the quasi-static approach, the damping coefficient is calculated from the normal force measured on a yawed cylinder. The range of the small ratios between the oscillation and the axial flow velocities corresponds to a range of low yaw angle where the cylinder is in near-axial flow in statics. The case of a yawed cylinder has been studied both experimentally with experiments in a wind tunnel and numerically with CFD calculations. The analyses of the fluid forces shows that for yaw angles smaller than 5 degrees, a linear lift with the yaw angle creates the damping. The origin of the lift force is discussed from pressure and velocity measurements. The results of the quasi-static approach are compared to the results of the dynamical experiments. In a second part, an experimental study is performed on a rigid cylinder array made up of 40 cylinders oscillating in an axial flow. The normal force and the displacement of the cylinder array are measured simultaneously. The added mass and damping coefficient are calculated and their variation with the
Axial crystals macroscopic symmetry and tensor properties
Czech Academy of Sciences Publication Activity Database
Janovec, Václav
2017-01-01
Roč. 90, č. 1 (2017), s. 1-10 ISSN 0141-1594 Institutional support: RVO:68378271 Keywords : axial * polar * pseudopolar * chiral * enantiomorphism * optical activity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.060, year: 2016
Optimisation of efficiency of axial fans
Kruyt, Nicolaas P.; Pennings, P.C.; Faasen, R.
2014-01-01
A three-stage research project has been executed to develop ducted axial-fans with increased efficiency. In the first stage a design method has been developed in which various conflicting design criteria can be incorporated. Based on this design method, an optimised design has been determined
The design of axial shaftless pump
Schmirler, Michal; Netrebska, Hana
The axial shaftless pump with a rotary casing has been proposed. The pump is unique in its small space requirements and the ability to draw a liquid with a high content of impurities and fibers. Modern motor with an external commutation was used to propel the pump rotor. The pump can be used for both pumping of liquids and marine propulsion.
VERY SLOW SPEED AXIAL MOTION RELUCTANCE MOTOR
African Journals Online (AJOL)
Dr Obe
1984-09-01
Sep 1, 1984 ... VERY SLOW SPEED AXIAL MOTION RELUCTANCE MOTOR by. L. A. Agu. Electrical Engineering Department. University of Nigeria, Nsukka. ABSTRACT. This paper presents the scheme for a very slow speed linear machine which uses conventional laminations and with which speeds of the same low.
Aryabha~ and Axial Rotation of Earth
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 4. Aryabhata and Axial Rotation of Earth - Naksatra Dina (the Sidereal Day). Amartya Kumar Dutta. General Article Volume 11 Issue 4 April 2006 pp 56-74. Fulltext. Click here to view fulltext PDF. Permanent link:
Aryabhala and Axial Rotation of Earth
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 3. Aryabhata and Axial Rotation of Earth - Khagola (The Celestial Sphere). Amartya Kumar Dutta. General Article Volume 11 Issue 3 March 2006 pp 51-68. Fulltext. Click here to view fulltext PDF. Permanent link:
The axial polarizability of nucleons and nuclei
International Nuclear Information System (INIS)
Ericson, M.; Figureau, A.
1981-02-01
The part of the static nuclear axial polarizability arising from the nucleonic excitations is derived from the low energy expansion of the πN amplitude. It is shown that the contribution of the Δ intermediate state, though dominant, does not saturate the nucleonic response. A similar effect, though more pronounced, is known to occur for the magnetic susceptibility
Excitation modes in non-axial nuclei
International Nuclear Information System (INIS)
Leviatan, A.; Ginnochio, J.N.
1990-01-01
Excitation modes of non-axial quadrupole shapes are investigated in the framework of interacting boson models. Both γ-unstable and γ-rigid nuclear shapes are considered for systems with one type of boson as well as with proton-neutron bosons. 6 refs
Excitation modes in non-axial nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A.; Ginnochio, J.N.
1990-01-01
Excitation modes of non-axial quadrupole shapes are investigated in the framework of interacting boson models. Both {gamma}-unstable and {gamma}-rigid nuclear shapes are considered for systems with one type of boson as well as with proton-neutron bosons. 6 refs.
AERODYNAMIC DESIGN OF HIGH PRESSRE AXIAL FAN
Directory of Open Access Journals (Sweden)
Y. A. Ryzhov
2014-01-01
Full Text Available The paper presents the results of numerical studies of flow in a high axial fan of H-2, the geometric parameters are carefully designed by the author. The coefficients of performance, the total pressure, efficiency and capacity. Shows the benefits of fan of H-2 on several other fans, expressed in increased efficiency with equal dimensions and angles of blade setting.
Co-axial, high energy gamma generator
Reijonen, Jani Petteri [Princeton, NJ; Gicquel, Frederic [Pennington, NJ
2011-08-16
A gamma ray generator includes an ion source in a first chamber. A second chamber is configured co-axially around the first chamber at a lower second pressure. Co-axially arranged plasma apertures separate the two chambers and provide for restricted passage of ions and gas from the first to the second chamber. The second chamber is formed by a puller electrode having at least one long channel aperture to draw ions from the first chamber when the puller electrode is subject to an appropriate applied potential. A plurality of electrodes rings in the third chamber in third pressure co-axially surround the puller electrode and have at least one channel corresponding to the at least one puller electrode aperture and plasma aperture. The electrode rings increase the energy of the ions to a selected energy in stages in passing between successive pairs of the electrodes by application of an accelerating voltage to the successive pairs of accelerator electrodes. A target disposed co-axially around the plurality of electrodes receives the beam of accelerated ions, producing gamma rays.
uper-resolution Axial Localization of Ultrasound Scatter Using Multi-focal Imaging
DEFF Research Database (Denmark)
Diamantis, Konstantinos; Greenaway, Alan H.; Anderson, Tom
2017-01-01
to noise ratio in each image. Conclusion: Super-resolution axial imaging from optical microscopy has been successfully translated into ultrasound imaging by using raw ultrasound data and standard beamforming. Significance: The normalized sharpness method has the potential to be used in scatterer...... localization applications and contribute in current super-resolution ultrasound imaging techniques.......This paper aims to develop a method for achieving micrometre axial scatterer localization for medical ultrasound, surpassing the inherent, pulse length dependence limiting ultrasound imaging. Methods: The method, directly translated from cellular microscopy, is based on multi-focal imaging...
Analysis of Mechanical Failure of Polymer Microneedles by Axial Force
Park, Jung-Hwan; Prausnitz, Mark R.
2010-01-01
A polymeric microneedle has been developed for drug delivery applications. The ultimate goal of the polymeric microneedle is insertion into the specified region without failure for effective transdermal drug delivery. Mechanical failure of various geometries of microneedles by axial load was modeled using the Euler formula and the Johnson formula to predict the failure force of tapered-column microneedles. These formulas were compared with measured data to identify the mechanical behavior of microneedles by determining the critical factors including the actual length and end-fixed factor. The comparison of the two formulas with the data showed good agreement at the end-fixity (K) of 0.7. This value means that a microneedle column has one fixed end and one pinned end, and that part of the microneedle was overloaded by axial load. When the aspect ratio of length to equivalent diameter is 12:1 at 3 GPa of Young’s modulus, there is a transition from the Euler region to the Johnson region by the decreased length and increased base diameter of the microneedle. A polymer having less than 3 GPa of stiffness would follow the Euler formula. A 12:1 aspect ratio of length to equivalent diameter of the microneedle was the mechanical indicator determining the failure mode between elastic buckling and inelastic buckling at less than 3 GPa of Young’s modulus of polymer. Microneedles with below a 12:1 aspect ratio of length-to-equivalent diameter and more than 3 GPa of Young’s were recommended for reducing sudden failure by buckling and for successfully inserting the microneedle into the skin. PMID:21218133
Axial and parity anomalies and vacuum charge: A direct approach
International Nuclear Information System (INIS)
Boyanovsky, D.; Blankenbecler, R.
1985-01-01
We study the axial and parity anomalies in Abelian gauge theories using the direct yet intuitive approach of counting the relative number of states of one chirality with respect to the other. A fundamental gauge-invariant quantity, the determinantal ratio, is introduced for this purpose. We find that the number of states is conserved and that the gauge fields differentially phase shift states of opposite chirality at infinite energies. This implies a relative flow of states at very large energies which must be compensated by a rearrangement of the density of states at finite energies. We then derive a sum rule which yields two alternative formulas for the index of a Dirac operator. One expresses the index in terms of its high-energy behavior, and the other in terms of the low-energy properties; these are the ''zero modes'' of definite chirality. Two examples are worked out in detail to clarify our general result. The physics of the axial anomaly is shown to translate into that of the parity anomaly in 2+1 dimensions, in which parity and chirality have interchanged roles. We also analyze the vacuum charge in regard to its high- and low-energy origin. The possibility of spectral flow is formulated and briefly discussed. In short, we provide a physical interpretation of certain mathematical indices, relate them to an extended version of Levinson's theorem of potential scattering, and simplify their evaluation
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
Energy Technology Data Exchange (ETDEWEB)
Wagner, J.C.; DeHart, M.D.
2000-03-01
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ``end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified.
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
International Nuclear Information System (INIS)
Wagner, J.C.; DeHart, M.D.
2000-01-01
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ''end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified
Effect of Turbine Axial Nozzle-Wheel Clearance on Performance of Mark 25 Torpedo Power Plant
Hoyt, Jack W.; Kottas, Harry
1948-01-01
Investigations were made of the turbine from a Mark 25 torpedo to determine the performance of the unit with three different turbine nozzles at various axial nozzle-wheel clearances. Turbine efficiency with a reamed nondivergent nozzle that uses the axial clearance space for gas expansion was little affected by increasing the axial running clearance from 0.030 to 0.150 inch. Turbine efficiency with cast nozzles that expanded the gas inside the nozzle passage was found to be sensitive to increased axial nozzle-wheel clearance. A cast nozzle giving a turbine brake efficiency of 0.525 at an axial running clearance of 0.035 inch gave a brake efficiency of 0.475 when the clearance was increased to 0.095 inch for the same inlet-gas conditions and blade-jet speed ratio. If the basis for computing the isentropic power available to the turbine is the temperature inside the nozzle rather then the temperature in the inlet-gas pipe, an increase in turbine efficiency of about 0.01 is indicated.
Hydrodynamics and axial mixing in a packed gas-liquid column
Directory of Open Access Journals (Sweden)
Barjaktarović Branislava G.
2003-01-01
Full Text Available The objective of this study was to investigate the pilot-plant gas absorption packed column hydrodynamics, as well as axial mixing in the system air-water. The pressure drop and the gas phase holdup data were determined in dependence on the flow rates of gas and liquid phases. The influence of superficial velocities of liquid and gas phases on the liquid axial dispersion in a gas-liquid packed bed column (ID 15 cm consisting of Raschig rings (15x15x2 mm were investigated. The pressure drop was measured with a U-type manometer, connected to the bottom and the top of the working part of the column. The gas phase holdup data in the air-water two-phase system was calculated as a ratio of the gas phase volume to the total volume of the two-phase system. Axial dispersion in the water phase has been determined by examining of the distribution of residence times of a salt tracer (NaCl in the packed bed. The tracer was injected in the liquid flow above the packed bed; samples of liquid were simultaneously taken from two sites at 1 m distance along the bed. Salt concentrations in the samples were determined by conductivity measurements. The mean residence time and the axial dispersion number were calculated by the moment method. The axial dispersion increases with an increase of liquid flow velocities and decrease of superficial air velocities.
Axial Ge/Si nanowire heterostructure tunnel FETs.
Energy Technology Data Exchange (ETDEWEB)
Dayeh, Shadi A. (Los Alamos National Laboratory); Gin, Aaron V.; Huang, Jian Yu; Picraux, Samuel Thomas (Los Alamos National Laboratory)
2010-03-01
Axial Ge/Si heterostructure nanowires (NWs) allow energy band-edge engineering along the axis of the NW, which is the charge transport direction, and the realization of asymmetric devices for novel device architectures. This work reports on two significant advances in the area of heterostructure NWs and tunnel FETs: (i) the realization of 100% compositionally modulated Si/Ge axial heterostructure NWs with lengths suitable for device fabrication and (ii) the design and implementation of Schottky barrier tunnel FETs on these NWs for high-on currents and suppressed ambipolar behavior. Initial prototype devices with 10 nm PECVD SiN{sub x} gate dielectric resulted in a very high current drive in excess of 100 {micro}A/{micro}m (I/{pi}D) and 10{sup 5} I{sub on}/I{sub off} ratios. Prior work on the synthesis of Ge/Si axial NW heterostructures through the VLS mechanism have resulted in axial Si/Si{sub 1-x}Ge{sub x} NW heterostructures with x{sub max} {approx} 0.3, and more recently 100% composition modulation was achieved with a solid growth catalyst. In this latter case, the thickness of the heterostructure cannot exceed few atomic layers due to the slow axial growth rate and concurrent radial deposition on the NW sidewalls leading to a mixture of axial and radial deposition, which imposes a big challenge for fabricating useful devices form these NWs in the near future. Here, we report the VLS growth of 100% doping and composition modulated axial Ge/Si heterostructure NWs with lengths appropriate for device fabrication by devising a growth procedure that eliminates Au diffusion on the NW sidewalls and minimizes random kinking in the heterostructure NWs as deduced from detailed microscopy analysis. Fig. 1 a shows a cross-sectional SEM image of epitaxial Ge/Si axial NW heterostructures grown on a Ge(111) surface. The interface abruptness in these Ge/Si heterostructure NWs is of the order of the NW diameter. Some of these NWs develop a crystallographic kink that is {approx
Piping inspection carriage having axially displaceable sensor
Zollinger, W.T.; Treanor, R.C.
1994-12-06
A pipe inspection instrument carriage is described for use with a pipe crawler for performing internal inspections of piping surfaces. The carriage has a front leg assembly, a rear leg assembly and a central support connecting the two assemblies and for mounting an instrument arm having inspection instruments. The instrument arm has a Y-arm mounted distally thereon for axially aligning the inspection instrumentation and a mounting block, a linear actuator and axial movement arm for extending the inspection instruments radially outward to operably position the inspection instruments on the piping interior. Also, the carriage has a rotation motor and gear assembly for rotating the central support and the front leg assembly with respect to the rear leg assembly so that the inspection instruments azimuthally scan the piping interior. The instrument carriage allows performance of all piping inspection operations with a minimum of moving parts, thus decreasing the likelihood of performance failure. 4 figures.
Ventajas de los motores de flujo axial
Directory of Open Access Journals (Sweden)
Alberto M Basanta Otero
2011-03-01
Full Text Available Es importante conocer sobre una familia de motores que a diferencia de los convencionales o tradicionales no presentanun flujo rotatorio radial, denominados motores de flujo axial. Dichos motores presentan altos valores de par motriz abajas velocidades, una alta eficiencia y alta densidad de potencia. Este trabajo constituye un breve análisis dealgunos motores de la referencia bibliográfica. Is important to know about a family of motors that at difference whit the traditional, don't have a rotator radial flux,called, axial flux motors. These motors have high torque for low speed, high efficiency and high power density. Thiswork is a brief analysis of several motors of the bibliographic references.
Cross-flow filtration and axial filtration
International Nuclear Information System (INIS)
Kraus, K.A.
1974-01-01
Two relatively novel alternative solid-liquid-separation techniques of filtration are discussed. In cross-flow filtration, the feed is pumped past the filtering surface. While in axial filtration the filter, mounted on a rotor, is moved with respect to the feed. While large-scale application of the axial filter is still in doubt, it permits with little expenditure of time and money, duplication of many hydrodynamic aspects of cross-flow filtration for fine-particle handling problems. The technique has been applied to municipal wastes, low-level radioactive waste treatment plant, lead removal from industrial wastes, removal of pulp-mill contaminants, textile-mill wastes, and pretreatment of saline waters by lime-soda process in preparation for hyperfiltration. Economics and energy requirements are also discussed
Nonleptonic B decays to axial-vector mesons and factorization
International Nuclear Information System (INIS)
Laporta, V.; Nardulli, G.; Pham, T. N.
2006-01-01
We present an analysis of two-body B decays with a pseudoscalar (P) and an axial-vector meson (A) in the final state using factorization. We employ as inputs a limited number of experimental data, i.e. results for the B→K 1 γ, and B→K*γ radiative decays and the branching ratios for B→πρ, πK*, Kρ, Kπ nonleptonic decays. In this way we are able to compare our predictions with recent data from the Belle and BABAR collaborations on B→a 1 π and make predictions on several other B→PA decay channels, which might be used as a guide for experimental researches and as tests of factorization
Development of throughflow calculation code for axial flow compressors
International Nuclear Information System (INIS)
Kim, Ji Hwan; Kim, Hyeun Min; No, Hee Cheon
2005-01-01
The power conversion systems of the current HTGRs are based on closed Brayton cycle and major concern is thermodynamic performance of the axial flow helium gas turbines. Particularly, the helium compressor has some unique design challenges compared to the air-breathing compressor such as high hub-to-tip ratios throughout the machine and a large number of stages due to the physical property of the helium and thermodynamic cycle. Therefore, it is necessary to develop a design and analysis code for helium compressor that can estimate the design point and off-design performance accurately. KAIST nuclear system laboratory has developed a compressor design and analysis code by means of throughflow calculation and several loss models. This paper presents the outline of the development of a throughflow calculation code and its verification results
Axial pattern skin flaps in cats.
Remedios, A M; Bauer, M S; Bowen, C V; Fowler, J D
1991-01-01
The major direct cutaneous vessels identified in the cat include the omocervical, thoracodorsal, deep circumflex iliac, and caudal superficial epigastric arteries. Axial pattern skin flaps based on the thoracodorsal and caudal superficial epigastric arteries have been developed in cats. Rotation of these flaps as islands allows skin coverage to the carpus and metatarsus, respectively. The thoracodorsal and caudal superficial epigastric flaps provide a practical, one-step option in the reconstruction of large skin defects involving the distal extremities of cats.
Atlanto-axial subluxation: a case report
Thurlow, Robert D
1988-01-01
One of the causes of death in rheumatoid patients is cord compression following atlanto-axial subluxation. Dislocations in the cervical spine are common with patients who have rheumatoid arthritis. Anterior subluxation occurs in up to 35%, followed by vertical subluxation in 22.2%, lateral subluxation in 20.6% and rarely posterior subluxation. A case report is presented to illustrate such a complication.
Axial flux permanent magnet brushless machines
Gieras, Jacek F; Kamper, Maarten J
2008-01-01
Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators
Cervical Spine Axial Rotation Goniometer Design
Emin Ulaş Erdem; Filiz Can
2012-01-01
To evaluate the cervical spine rotation movement is quiet harder than other joints. Configuration and arrangement of current goniometers and devices is not always practic in clinics and some methods are quiet expensive. The cervical axial rotation goniometer designed by the authors is consists of five pieces (head apparatus, chair, goniometric platform, eye pads and camera). With this goniometer design a detailed evaluation of cervical spine range of motion can be obtained. Besides, measureme...
Axial gravity, massless fermions and trace anomalies
Energy Technology Data Exchange (ETDEWEB)
Bonora, L. [International School for Advanced Studies (SISSA), Trieste (Italy); KEK, Tsukuba (Japan). KEK Theory Center; INFN, Sezione di Trieste (Italy); Cvitan, M.; Giaccari, S.; Stemberga, T. [Zagreb Univ. (Croatia). Dept. of Physics; Prester, P.D. [Rijeka Univ. (Croatia). Dept. of Physics; Pereira, A.D. [UERJ-Univ. Estadual do Rio de Janeiro (Brazil). Dept. de Fisica Teorica; UFF-Univ. Federal Fluminense, Niteroi (Brazil). Inst. de Fisica
2017-08-15
This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones. (orig.)
Axial polarizability and weak currents in nuclei
International Nuclear Information System (INIS)
Ericson, M.
1977-01-01
The weak interaction nucleonic coupling constants in nuclei are modified by the presence of the neighbouring nucleons. One type of modification is due to the virtual excitation of the isobars through meson exchange. The influence of the isobars is described by means of the nuclear axial polarizability coefficient. This polarizability is known; it is linked to the p-wave πN scattering volume. A relation is derived between the axial nuclear current and the pion field which incorporates the polarizability effects. This relation has an electromagnetic analogue. It is then possible to derive the axial and pseudoscalar coupling constants from a knowledge of the pion field. This field in turn obeys a Klein-Gordon equation which has to include the isobaric excitations. The propagation of the pion field is similar to that of an electromagnetic wave in a dielectric medium. The strong interaction coupling constant is shown to be renormalized in nuclei by the effect of the various types of correlations. (author)
Dynamic control of knee axial deformities
Directory of Open Access Journals (Sweden)
E. E. Malyshev
2013-01-01
Full Text Available The authors have evaluated the clinical examination of the patients with axial malalignments in the knee by the original method and device which was named varovalgometer. The measurements were conducted by tension of the cord through the spina iliaca anterior superior and the middle of the lower pole of patella. The deviation of the center of the ankle estimated by metal ruler which was positioned perpendicular to the lower leg axis on the level of the ankle joint line. The results of comparison of our method and computer navigation in 53 patients during the TKA show no statistically significant varieties but they differ by average 5° of valgus in clinical examination in comparison with mechanical axis which was identified by computer navigation. The dynamic control of axial malalignment can be used in clinical practice for estimation of the results of treatment of pathology with axial deformities in the knee; for the control of reduction and secondary displacement of the fractures around the knee; for assessment of instability; in planning of correctional osteotomies and intraoperative control of deformity correction; for estimation of Q angle in subluxation and recurrent dislocation of patella; in planning of TKA; during the growth of child it allows to assess the progression of deformity.
Respiratory effects of transient axial acceleration.
Loring, S H; Lee, H T; Butler, J P
2001-06-01
Whereas gravity has an inspiratory effect in upright subjects, transient upward acceleration is reported to have an expiratory effect. To explore the respiratory effects of transient axial accelerations, we measured axial acceleration at the head and transrespiratory pressure or airflow in five subjects as they were dropped or lifted on a platform. For the first 100 ms, upward acceleration caused a decrease in mouth pressure and inspiratory flow, and downward acceleration caused the opposite. We also simulated these experimental observations by using a computational model of a passive respiratory system based on anatomical data and normal respiratory characteristics. After 100 ms, respiratory airflow in our subjects became highly variable, no longer varying with acceleration. Electromyograms of thoracic and abdominal respiratory muscles showed bursts of activity beginning 40-125 ms after acceleration, suggesting reflex responses responsible for subsequent flow variability. We conclude that, in relaxed subjects, transient upward axial acceleration causes inspiratory airflow and downward acceleration causes expiratory airflow, but that after ~100 ms, reflex activation of respiratory musculature largely determines airflow.
Atlanto-Axial Subluxation After Adenoidectomy.
Gross, Isabel Theresia; Bahar-Posey, Laleh
2017-06-01
Atlanto-axial subluxation is a rare but potentially serious complication after otolaryngological procedures. We are describing a case of a 4-year-old child who developed atlanto-axial subluxation of the cervical spine after adenoidectomy. Our patient underwent adenoidectomy and, 18 days later, presented to the emergency department with her neck tilted to the left in a cock-robin position and complaining of neck pain persisting since the surgery. A multiplanar 3-dimensional computed tomography was obtained and confirmed the diagnosis of an atlanto-axial subluxation (Fielding type 3). She was managed conservatively with the application of a cervical collar, anti-inflammatory medication, and manual reduction under anesthesia later in the course because of persistence of her symptoms. It is important to consider this diagnosis in any child who undergoes ENT surgical procedures complaining of neck pain subsequent to surgery or holding the head in a fixed position persistently after surgery. Early diagnosis is important to reduce the time between the onset of symptoms and reduction to reduce the risk or need for surgical intervention.
The deep structure of Axial Volcano
West, Michael Edwin
The subsurface structure of Axial Volcano, near the intersection of the Juan de Fuca Ridge and the Cobb-Eickelberg seamount chain in the northeast Pacific, is imaged from an active source seismic experiment. At a depth of 2.25 to 3.5 km beneath Axial lies an 8 km x 12 km region of very low seismic velocities that can only be explained by the presence of magma. In the center of this magma storage chamber at 2--3.5 km below sea floor, the crust is at least 10--20% melt. At depths of 4--5 km there is evidence of additional low concentrations of magma (a few percent) over a larger area. In total, 5--11 km3 of magma are stored in the mid-crust beneath Axial. This is more melt than has been positively identified under any basaltic volcano on Earth. It is also far more than the 0.1--0.2 km3 emplaced during the 1998 eruption. The implied residence time in the magma reservoir of a few hundred to a few thousand years agrees with geochemical trends which suggest prolonged storage and mixing of magmas. The large volume of melt bolsters previous observations that Axial provides much of the material to create crust along its 50 km rift zones. A high velocity ring-shaped feature sits above the magma chamber just outside the caldera walls. This feature is believed to be the result of repeated dike injections from the magma body to the surface during the construction of the volcanic edifice. A rapid change in crustal thickness from 8 to 11 km within 15 km of the caldera implies focused delivery of melt from the mantle. The high flux of magma suggests that melting occurs deeper in the mantle than along the nearby ridge. Melt supply to the volcano is not connected to any plumbing system associated with the adjacent segments of the Juan de Fuca Ridge. This suggests that, despite Axial's proximity to the ridge, the Cobb hot spot currently drives the supply of melt to the volcano.
Energy Technology Data Exchange (ETDEWEB)
Lee, Ryan K.L.; Griffith, James F.; Ng, Alex W.H.; Law, Eric K.C. [The Chinese University of Hong Kong, Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, Hong Kong (China); Tse, W.L.; Wong, Clara W.Y.; Ho, P.C. [The Chinese University of Hong Kong, Department of Orthopedics and Traumatology, Prince Of Wales Hospital, Hong Kong (China)
2017-03-15
To compare axial and oblique axial planes on MR arthrography (MRA) and multidetector CT arthrography (CTA) to evaluate dorsal and volar parts of scapholunate (SLIL) and lunotriquetral interosseous (LTIL) ligaments. Nine cadaveric wrists of five male subjects were studied. The visibility of dorsal and volar parts of the SLIL and LTIL was graded semi-quantitatively (good, intermediate, poor) on MRA and CTA. The presence of a ligament tear was determined on arthrosocopy and sensitivity, specificity and accuracy of tear detection were calculated. Oblique axial imaging was particularly useful for delineating dorsal and volar parts of the LTIL on MRA with overall 'good' visibility increased from 11 % to 78 %. The accuracy of MRA and CTA in revealing SLIL and LTIL tear was higher using the oblique axial plane. The overall accuracy for detecting SLIL tear on CTA improved from 94 % to 100 % and from 89 % to 94 % on MRA; the overall accuracy of detecting LTIL tear on CTA improved from 89 % to 100 % and from 72 % to 89 % on MRA Oblique axial imaging during CT and MR arthrography improves detection of tears in the dorsal and volar parts of both SLIL and LTIL. (orig.)
Axial flow heat exchanger devices and methods for heat transfer using axial flow devices
Koplow, Jeffrey P.
2016-02-16
Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.
Timm, Gerald W; Elayaperumal, Santhi; Hegrenes, Jami
2008-07-01
pressure require more force to cause buckling than vessels at lower internal pressure. The circumferential displacement of a vessel under radial compression is higher in vessels of lower internal pressure and less in vessels of high internal pressure. The size of a vessel also contributes to its ability to be buckled. Smaller vessels buckle under smaller load, but the ratio of force required to buckle vs. diameter of the cylinder remained constant. The computer simulations show that with slight deviations from perfectly aligned axial loading the stresses felt on the walls of cylindrical columns vary considerably, whether they are isotropic beams or pressurized vessels. The material properties of the tissues within the corpora cause it to behave as a thin-walled pressurized vessel, in which the hoop stress and axial stress have a constant relationship independent of the length to diameter ratio rather than as an isotropic beam where this relationship varies. Patient discomfort and high operator dependency further contribute to the inconsistencies of axial loading methods to determine penile buckling. Based on the constant relationship between hoop stress and axial stress in thin-walled pressurized vessels this study confirms the validity and desirability of using radial compression methods to assess penile rigidity in lieu of axial loading methods.
QCD plasma parameters in axial gauge
Energy Technology Data Exchange (ETDEWEB)
Nachbagauer, H. (Technische Univ., Vienna (Austria). Inst. fuer Theoretische Physik)
1992-11-01
Within the framework of imaginary time formalism we investigate the structure of the gluon polarization tensor and relate its structure functions to the dispersion relation of plasma eigenmodes. To one loop order, we calculate the transversal structure function to leading order in the high temperature expansion as well as the first subleading order contribution in the long wavelength limit. The result is used to express the dynamical mass and the damping constant for transversal plasma eigenmodes. The aim of our present paper is a systematic discussion of the gauge fixing vector dependence of the damping constant. In the limit of temporal axial gauge we encounter a negative damping constant contradicting previous results. (orig.).
QCD plasma parameters in axial gauge
Nachbagauer, Herbert
1992-09-01
Within the framework of imaginary time formalism we investigate the structure of the gluon polarization tensor and relate its structure functions to the dispersion relation of plasma eigenmodes. To one loop order, we calculate the transversal structure function to leading order in the high temperature expansion as well as the first subleading order contribution in the long wavelength limit. The result is used to express the dynamical mass and the damping constant for transversal plasma eigenmodes. The aim of our present paper is a systematic discussion of the gauge fixing vector dependence of the damping constant. In the limit of temporal axial gauge we encounter a negative damping constant contradicting previous results.
Disordered axial movement in Parkinson's disease.
Steiger, M J; Thompson, P D; Marsden, C D
1996-01-01
Axial motor impairments are a common cause of disability in patients with Parkinson's disease, become more prominent with longer disease duration, and have been said to be less responsive to levodopa replacement therapy. The ability to turn in bed while lying supine before and after dopaminergic stimulation was studied in a group of 36 patients with Parkinson's disease; 23 were in Hoehn and Yahr stages 3-5 when "off", and 13 were in stages 1-2. Turning was also compared with postural stabilit...
Ankylosing Spondylitis versus Nonradiographic Axial Spondyloarthritis
DEFF Research Database (Denmark)
Glintborg, Bente; Sørensen, Inge J; Østergaard, Mikkel
2017-01-01
OBJECTIVE: To compare baseline disease activity and treatment effectiveness in biologic-naive patients with nonradiographic axial spondyloarthritis (nr-axSpA) and ankylosing spondylitis (AS) who initiate tumor necrosis factor inhibitor (TNFi) treatment and to study the role of potential confounders....../disease duration/TNFi-type/smoking/baseline disease activity) on TNFi adherence and response [e.g., Bath Ankylosing Spondylitis Activity Index (BASDAI) 50%/20 mm]. RESULTS: The study included 1250 TNFi-naive patients with axSpA (29% nr-axSpA, 50% AS, 21% lacked radiographs of sacroiliac joints). Patients...
Cervical Spine Axial Rotation Goniometer Design
Directory of Open Access Journals (Sweden)
Emin Ulaş Erdem
2012-06-01
Full Text Available To evaluate the cervical spine rotation movement is quiet harder than other joints. Configuration and arrangement of current goniometers and devices is not always practic in clinics and some methods are quiet expensive. The cervical axial rotation goniometer designed by the authors is consists of five pieces (head apparatus, chair, goniometric platform, eye pads and camera. With this goniometer design a detailed evaluation of cervical spine range of motion can be obtained. Besides, measurement of "joint position sense" which is recently has rising interest in researches can be made practically with this goniometer.
Piezoelectric potential in axial (In,Ga)N/GaN nanowire heterostructures
Kaganer, Vladimir M.; Marquardt, Oliver; Brandt, Oliver
2016-04-01
We derive analytic expressions for the built-in electrostatic potential arising from piezo- and pyroelectricity in a cylindrical axial In x Ga{}1-xN/GaN nanowire (NW) heterostructure. Our simulations show that, for sufficiently thin NWs, a significant reduction of the built-in potential is reached in comparison to the planar heterostructure of the same In content, thickness, and orientation. This specific feature of axial NW heterostructures makes the aspect ratio of the embedded In x Ga{}1-xN disks an important additional degree of freedom to control the recombination energies. We furthermore show that the magnitude of the polarization potential decreases again above a certain value of the aspect ratio and that the extrema of the potential move from the central axis of the NW towards the side facets when the thickness of the disk is increased.
Design of HTS tri-axial cable in steady-state operation
Energy Technology Data Exchange (ETDEWEB)
Hu, N., E-mail: hunannan@ecei.tohoku.ac.j [Electrical Engineering Department, Graduate School, Tohoku University, 6-6-05 Aoba Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Toda, M.; Ozcivan, A.N.; Yagai, T.; Tsuda, M.; Hamajima, T. [Electrical Engineering Department, Graduate School, Tohoku University, 6-6-05 Aoba Aramaki, Aoba-ku, Sendai 980-8579 (Japan)
2010-11-01
By the advantage of more compact structure, small leakage field, and low heat loss, tri-axial cable become to be mainstream design in recently HTS practical project. However, the imbalance current problem was also reported by some practice experiments. Since the HTS tri-axial cable is composed of three concentric phases, an unsymmetrical inductance and capacitance distribution which is determined by twist pitches and radii, gives an inherent imbalance in three-phase currents distribution. In our previous research, we proposed a two sections structure design to overcome this limitation. Inductance has been balanced by twist pitch adjusting. In that case, the imbalance ratio of current only can be caused by capacitance distribution which is depending on voltage and line length. In this paper, we evaluate the thickness of insulation, the unsymmetrical capacitance distribution and cable fabrication error. Then we investigate the imbalance ratio due to the capacitance as functions of voltage and length by using Electromagnetic Transients Program (EMTP).
Medullary sponge kidney on axial computed tomography
International Nuclear Information System (INIS)
Ginalski, J.-M.; Schnyder, Pierre; Portmann, Luc; Jaeger, Philippe
1991-01-01
To evaluate features of medullary sponge kidney (MSK) on computed tomography (CT), 4-mm-thick axial slices without intravenous contrast material were 1st made in 13 patients through 24 kidneys which showed images of MSK on excretory urograms. On CT, papillary calcifications were found in 11 kidneys. In 5 of these, the calcifications were not detectable on plain films. Some hyperdense papillae (attenuation value 55-70 Hounsfield units) without calcification were found in 4 other kidneys. 9 kidneys appeared normal. 10 of the 14 kidneys were reexamined by a 2nd series of 4-mm-thick axial slices, 5 min after intravenous injection of 50 ml of Urografin. Images suggesting possible ectasia of precaliceal tubules were found in only 4 kidneys. These images appear much less obvious and characteristic on CT than on excretory urogram and do nothing more than suggest the possibility of MSK. In conclusion, the sensitivity of CT in the detection of MSK is markedly lower than that of excretory urography. In the most florid cases of the disease, CT can only show images suggesting the possibility of MSK. On the other hand, CT appears much more sensitive than plain films and tomograms of excretory in the detection of papillary calcifications, the most frequent complication of MSK. (author). 13 refs.; 3 figs
Axial tomography in live cell laser microscopy
Richter, Verena; Bruns, Sarah; Bruns, Thomas; Weber, Petra; Wagner, Michael; Cremer, Christoph; Schneckenburger, Herbert
2017-09-01
Single cell microscopy in a three-dimensional (3-D) environment is reported. Cells are grown in an agarose culture gel, located within microcapillaries and observed from different sides after adaptation of an innovative device for sample rotation. Thus, z-stacks can be recorded by confocal microscopy in different directions and used for illustration in 3-D. This gives additional information, since cells or organelles that appear superimposed in one direction, may be well resolved in another one. The method is tested and validated with single cells expressing a membrane or a mitochondrially associated green fluorescent protein, or cells accumulating fluorescent quantum dots. In addition, axial tomography supports measurements of cellular uptake and distribution of the anticancer drug doxorubicin in the nucleus (2 to 6 h after incubation) or the cytoplasm (24 h). This paper discusses that upon cell rotation an enhanced optical resolution in lateral direction compared to axial direction can be utilized to obtain an improved effective 3-D resolution, which represents an important step toward super-resolution microscopy of living cells.
Axial vessel widening in arborescent monocots.
Petit, Giai; DeClerck, Fabrice A J; Carrer, Marco; Anfodillo, Tommaso
2014-02-01
Dicotyledons have evolved a strategy to compensate for the increase in hydraulic resistance to water transport with height growth by widening xylem conduits downwards. In monocots, the accumulation of hydraulic resistance with height should be similar, but the absence of secondary growth represents a strong limitation for the maintenance of xylem hydraulic efficiency during ontogeny. The hydraulic architecture of monocots has been studied but it is unclear how monocots arrange their axial vascular structure during ontogeny to compensate for increases in height. We measured the vessel lumina and estimated the hydraulic diameter (Dh) at different heights along the stem of two arborescent monocots, Bactris gasipaes (Kunth) and Guadua angustifolia (Kunth). For the former, we also estimated the variation in Dh along the leaf rachis. Hydraulic diameter increased basally from the stem apex to the base with a scaling exponent (b) in the range of those reported for dicot trees (b = 0.22 in B. gasipaes; b = 0.31 and 0.23 in G. angustifolia). In B. gasipaes, vessels decrease in Dh from the stem's centre towards the periphery, an opposite pattern compared with dicot trees. Along the leaf rachis, a pattern of increasing Dh basally was also found (b = 0.13). The hydraulic design of the monocots studied revealed an axial pattern of xylem conduits similar to those evolved by dicots to compensate and minimize the negative effect of root-to-leaf length on hydrodynamic resistance to water flow.
Modeling the axial offset anomaly in PWRs
Energy Technology Data Exchange (ETDEWEB)
Blok, J.; Chauffriat, S.; Frattini, P. [EPRI, Palo Alto, CA (United States)
2002-07-01
Axially un-symmetrical flux depression is defined as axial offset anomaly (AOA) in PWRs. The effect has only been observed in PWR reactor cores operated at high power duty. The threat of AOA limits the aggressiveness of core design, and in extreme form, the effect can decrease shutdown margin near end of cycle (EOC) sufficiently to mandate power reduction. AOA is ultimately the result of boron hideout on fuel. Studies have confirmed that sufficient boron hideout to produce measurable AOA requires relatively large amounts of corrosion products to deposit on the fuel. Because corrosion product deposition is favored in the boiling upper regions of the (high duty) core, the amount of boron uptake in these regions is large in proportion, and core reactivity is affected disproportionately in the upper region of the core. This paper explores possible mechanisms for deposition of corrosion products on fuel and the consequent incorporation of boron compounds. The proposed mechanisms are viewed in the context of corrosion product samples from the Callaway Cycle 9, one of the PWR fuel cycles that exhibited the most severe AOA to date. (author)
Analysis of Burning Processes in Turbulent Mixing Axial and Tangential Flows
Directory of Open Access Journals (Sweden)
R. I. Essmann
2009-01-01
Full Text Available The paper demonstrates that in the case of turbulent diffusion flame tongues the burning process of combined multiphase fuel is determined by flow structure and conditions for mixing various types of fuel and distributed oxidizer flows. It has been determined that the ratio of air supplied for burning through axial and tangential channels governs a shape of the flame tongue, its size and process intensity that allows efficiently to optimize technological parameters.
The effect of multi-axiality on damage with alternating stress
International Nuclear Information System (INIS)
Hug, J.; Zenner, H.; Schram, A.
1992-01-01
The aim of this project is a better understanding of the development of damage with multi-axial alternating stress. Hollow samples of the materials X6 CrNiTi 18 0 and Ck 15 are submitted to equal phase, phase displaced and consecutively alternating normal and thrust stresses. The amplitude ratio τ/σ is 1/2. Apart from the service life, the cyclic alternating deformation behaviour and the initiation and prapagation of microcracks are examined. (orig./MM) [de
Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions
Directory of Open Access Journals (Sweden)
Othuman Mydin M.A.
2014-01-01
Full Text Available Lightweight foamcrete is a versatile material; primarily consist of a cement based mortar mixed with at least 20% volume of air. High flow ability, lower self-weight, minimal requirement of aggregate, controlled low strength and good thermal insulation properties are a few characteristics of foamcrete. Its dry densities, typically, is below 1600kg/m3 with compressive strengths maximum of 15MPa. The ASTM standard provision specifies a correction factor for concrete strengths of between 14 and 42MPa to compensate for the reduced strength when the aspect height-to-diameter ratio of specimen is less than 2.0, while the CEB-FIP provision specifically mentions the ratio of 150 x 300mm cylinder strength to 150 mm cube strength. However, both provisions requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength of foamcrete. This proposed laboratory work is intended to study the effect of different dimensions and profiles on the axial compressive strength of concrete. Specimens of various dimensions and profiles are cast with square and circular cross-sections i.e., cubes, prisms and cylinders, and to investigate their behavior in compression strength at 7 and 28 days. Hypothetically, compressive strength will decrease with the increase of concrete specimen dimension and concrete specimen with cube profile would yield comparable compressive strength to cylinder (100 x 100 x 100mm cube to 100dia x 200mm cylinder.
Concrete-Filled-Large Deformable FRP Tubular Columns under Axial Compressive Loading
Directory of Open Access Journals (Sweden)
Omar I. Abdelkarim
2015-10-01
Full Text Available The behavior of concrete-filled fiber tubes (CFFT polymers under axial compressive loading was investigated. Unlike the traditional fiber reinforced polymers (FRP such as carbon, glass, aramid, etc., the FRP tubes in this study were designed using large rupture strains FRP which are made of recycled materials such as plastic bottles; hence, large rupture strain (LRS FRP composites are environmentally friendly and can be used in the context of green construction. This study performed finite element (FE analysis using LS-DYNA software to conduct an extensive parametric study on CFFT. The effects of the FRP confinement ratio, the unconfined concrete compressive strength ( , column size, and column aspect ratio on the behavior of the CFFT under axial compressive loading were investigated during this study. A comparison between the behavior of the CFFTs with LRS-FRP and those with traditional FRP (carbon and glass with a high range of confinement ratios was conducted as well. A new hybrid FRP system combined with traditional and LRS-FRP is proposed. Generally, the CFFTs with LRS-FRP showed remarkable behavior under axial loading in strength and ultimate strain. Equations to estimate the concrete dilation parameter and dilation angle of the CFFTs with LRS-FRP tubes and hybrid FRP tubes are suggested.
Axial dispersion in a Kureha Crystal Purifier (KCP)
Otawara, K.; Matsuoka, T.
2002-04-01
It is widely accepted that the degree of axial back-mixing in the equipment affects the performance of a column crystallizer. Specifically, small such mixing is inevitable for obtaining highly pure crystal. In fact, it is believed that scale-up of some column crystallizers has been terminated due to the large axial back-mixing or maldistribution. Thus, experiments have been performed for estimating axial dispersion coefficients of liquid phase representing axial back-mixing in the column of a Kureha Crystal Purifier (KCP). The effect of the column diameter on such coefficients has been investigated and it has become evident that the axial back-mixing in the column is more significant in the larger column. Nevertheless, the results have also indicated that the axial back-mixing in KCPs of industrial sizes can be substantially smaller than those in other types of column crystallizers.
Axial stress corrosion cracking forming method to metal tube
International Nuclear Information System (INIS)
Araki, Kumiko
1998-01-01
Generally, it is more difficult in a metal tube, to intentionally cause a stress corrosion cracking in axial direction than in circumferential direction. In the present invention, a bevel is formed on a metal tube and welding is conducted in circumferential direction along the bevel, and welding is conducted in axial direction partially to the portion welded in circumferential direction. Namely, a bevel is formed in circumferential direction to an abutting portion of thick-walled metal tubes with each other, welding is conducted in circumferential direction along the bevel, and welding is conducted in axial direction partially to a portion welded in circumferential direction. With such procedures, since tensile stress in the circumferential direction is increased partially at a portion welded in axial direction, stress corrosion cracking is caused in axial direction at the portion. Then, stress corrosion cracking in axial direction can thus be formed on the thick-walled metal tube. (N.H.)
Revisiting the vector and axial-vector vacuum susceptibilities
International Nuclear Information System (INIS)
Chang Lei; Liu Yuxin; Sun Weimin; Zong Hongshi
2008-01-01
We re-investigate the vector and axial-vector vacuum susceptibilities by taking advantage of the vector and axial-vector Ward-Takahashi identities. We show analytically that, in the chiral limit, the vector vacuum susceptibility is zero and the axial-vector vacuum susceptibility equals three fourths of the square of the pion decay constant. Besides, our analysis reproduces the Weinberg sum rule
On the Poisson’s ratio of the nucleus pulposus.
Farrell, M D; Riches, P E
2013-10-01
Existing experimental data on the Poisson’s ratio of nucleus pulposus (NP) tissue is limited. This study aims to determine whether the Poisson’s ratio of NP tissue is strain-dependent, strain-rate-dependent, or varies with axial location in the disk. Thirty-two cylindrical plugs of bovine tail NP tissue were subjected to ramphold unconfined compression to 20% axial strain in 5% increments, at either 30 lm/s or 0.3 lm/s ramp speeds and the radial displacement determined using biaxial video extensometry. Following radial recoil, the true Poisson’s ratio of the solid phase of NP tissue increased linearly with increasing strain and demonstrated strain-rate dependency. The latter finding suggests that the solid matrix undergoes stress relaxation during the test. For small strains, we suggest a Poisson’s ratio of 0.125 to be used in biphasic models of the intervertebral disk
On the poisson's ratio of the nucleus pulposus.
Farrell, M D; Riches, P E
2013-10-01
Existing experimental data on the Poisson's ratio of nucleus pulposus (NP) tissue is limited. This study aims to determine whether the Poisson's ratio of NP tissue is strain-dependent, strain-rate-dependent, or varies with axial location in the disk. Thirty-two cylindrical plugs of bovine tail NP tissue were subjected to ramp-hold unconfined compression to 20% axial strain in 5% increments, at either 30 μm/s or 0.3 μm/s ramp speeds and the radial displacement determined using biaxial video extensometry. Following radial recoil, the true Poisson's ratio of the solid phase of NP tissue increased linearly with increasing strain and demonstrated strain-rate dependency. The latter finding suggests that the solid matrix undergoes stress relaxation during the test. For small strains, we suggest a Poisson's ratio of 0.125 to be used in biphasic models of the intervertebral disk.
Aerodynamic Modelling and Optimization of Axial Fans
DEFF Research Database (Denmark)
Sørensen, Dan Nørtoft
A numerically efficient mathematical model for the aerodynamics oflow speed axial fans of the arbitrary vortex flow type has been developed.The model is based on a blade-element principle, whereby therotor is divided into a number of annular streamtubes.For each of these streamtubes relations...... and integrated propertiesshow that the computed results agree well with the measurements.Integrating a rotor-only version of the aerodynamic modelwith an algorithm for numerical designoptimization, enables the finding of an optimum fan rotor.The angular velocity of the rotor, the hub radius and the spanwise...... of fan efficiency in a design interval of flow rates,thus designinga fan which operates well over a range of different flow conditions.The optimization scheme was used to investigate the dependence ofmaximum efficiency on1: the number of blades,2: the width of the design interval and3: the hub radius...
Geometric inequalities for axially symmetric black holes
International Nuclear Information System (INIS)
Dain, Sergio
2012-01-01
A geometric inequality in general relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities play an important role in the characterization of the gravitational collapse; they are closely related with the cosmic censorship conjecture. Axially symmetric black holes are the natural candidates to study these inequalities because the quasi-local angular momentum is well defined for them. We review recent results in this subject and we also describe the main ideas behind the proofs. Finally, a list of relevant open problems is presented. (topical review)
Collimated trans-axial tomographic scintillation camera
International Nuclear Information System (INIS)
1980-01-01
The objects of this invention are first to reduce the time required to obtain statistically significant data in trans-axial tomographic radioisotope scanning using a scintillation camera. Secondly, to provide a scintillation camera system to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a known radiation source without sacrificing spatial resolution. Thirdly to reduce the scanning time without loss of image clarity. The system described comprises a scintillation camera detector, means for moving this in orbit about a cranial-caudal axis relative to a patient and a collimator having septa defining apertures such that gamma rays perpendicular to the axis are admitted with high spatial resolution, parallel to the axis with low resolution. The septa may be made of strips of lead. Detailed descriptions are given. (U.K.)
Collimated trans-axial tomographic scintillation camera
International Nuclear Information System (INIS)
1980-01-01
The principal problem in trans-axial tomographic radioisotope scanning is the length of time required to obtain meaningful data. Patient movement and radioisotope migration during the scanning period can cause distortion of the image. The object of this invention is to reduce the scanning time without degrading the images obtained. A system is described in which a scintillation camera detector is moved to an orbit about the cranial-caudal axis relative to the patient. A collimator is used in which lead septa are arranged so as to admit gamma rays travelling perpendicular to this axis with high spatial resolution and those travelling in the direction of the axis with low spatial resolution, thus increasing the rate of acceptance of radioactive events to contribute to the positional information obtainable without sacrificing spatial resolution. (author)
Axial flux data for fuel measurement
Energy Technology Data Exchange (ETDEWEB)
Popovich, R.P.
1964-02-11
A survey of the PITA-18 nonpoisonous spline program was conducted in conjunction with a study to determine the best method of eliminating the variability of axial flux on the fuel performance parameter, q. The results of this survey and the conclusions reached in the rupture coefficient study were found to be inter-dependent such that both are presented in this report. The data from the PITA-18 nonpoisonous spline program, as received, is the output of the NOLA-2 computer program. One quantity of interest is the rupture potential relative to a cosine, commonly referred to as the relative rupture potential. As programmed, the relative rupture potential, which was derived by applying the rupture model to individual fuel elements, might be expected to vary linearly with the rupture rate. The use of the relative rupture potential was studied over the period of July 1962 through December 1963. The results of this study are presented.
Composite Axial Flow Propulsor for Small Aircraft
Directory of Open Access Journals (Sweden)
R. Poul
2005-01-01
Full Text Available This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element Method. The skin of the blade is calculated as a laminate and the foam core as a solid. A static and dynamic analysis were made. The RTM technology is compared with other technologies and is described in detail.
Estimation of ocular volume from axial length.
Nagra, Manbir; Gilmartin, Bernard; Logan, Nicola S
2014-12-01
To determine which biometric parameters provide optimum predictive power for ocular volume. Sixty-seven adult subjects were scanned with a Siemens 3-T MRI scanner. Mean spherical error (MSE) (D) was measured with a Shin-Nippon autorefractor and a Zeiss IOLMaster used to measure (mm) axial length (AL), anterior chamber depth (ACD) and corneal radius (CR). Total ocular volume (TOV) was calculated from T2-weighted MRIs (voxel size 1.0 mm(3)) using an automatic voxel counting and shading algorithm. Each MR slice was subsequently edited manually in the axial, sagittal and coronal plane, the latter enabling location of the posterior pole of the crystalline lens and partitioning of TOV into anterior (AV) and posterior volume (PV) regions. Mean values (±SD) for MSE (D), AL (mm), ACD (mm) and CR (mm) were -2.62±3.83, 24.51±1.47, 3.55±0.34 and 7.75±0.28, respectively. Mean values (±SD) for TOV, AV and PV (mm(3)) were 8168.21±1141.86, 1099.40±139.24 and 7068.82±1134.05, respectively. TOV showed significant correlation with MSE, AL, PV (all p<0.001), CR (p=0.043) and ACD (p=0.024). Bar CR, the correlations were shown to be wholly attributable to variation in PV. Multiple linear regression indicated that the combination of AL and CR provided optimum R(2) values of 79.4% for TOV. Clinically useful estimations of ocular volume can be obtained from measurement of AL and CR. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Hsu, Wen-Hsing; Benzel, Edward C; Chen, Tzu-Yung; Chen, Yao-Liang
2008-10-15
Computerized tomography and image processing methodologies were used to analyze the axial and coronal orientation of cervical zygapophysial joints in asymptomatic adults. Surface motions of axial rotation and lateral bending were simulated. The study was designed to obtain the normal distribution and variation of facet orientation (FO) in axial and coronal planes to investigate factors affecting FO and to study the effects of FO on axial rotation and lateral bending. The FO of the subaxial cervical spine is usually evaluated in the sagittal plane. Cervical spine axial and coronal FO is usually considered to be horizontal. The literature reveals no statistical data for axial or coronal FO. Serial thin-sliced computed tomography scans of the cervical spine in asymptomatic adults were input into Image J, National Institutes of Health, image processing software. Bilateral zygapophysial joint angles from C2-C3 to C6-C7 were measured in the axial and coronal planes and collected from 100 subjects. The effect of gender, age, and correlation was analyzed. The surface motions of axial rotation and lateral bending were simulated in Abaqus CAE 6.5. Mathematical facet contact and range of motion were computed. The FO was widely distributed at each level. Gender had no significant association with FO. Age affected FO at most levels. Axial and coronal FO were significantly correlated. The zygapophysial joint of internally rotated/inverted FO contacted more perpendicularly to each other, and mathematical range of motion was smaller. The axial or coronal FO of the subaxial cervical spine was found with more variability. Age was significantly related to FO. Geometrically, internally rotated/inverted FO of axial rotation/lateral bending was morerestricted. The extent of axial rotation and lateral bending was correlated with each other.
Improving axial resolution in confocal microscopy with new high refractive index mounting media.
Directory of Open Access Journals (Sweden)
Coralie Fouquet
Full Text Available Resolution, high signal intensity and elevated signal to noise ratio (SNR are key issues for biologists who aim at studying the localisation of biological structures at the cellular and subcellular levels using confocal microscopy. The resolution required to separate sub-cellular biological structures is often near to the resolving power of the microscope. When optimally used, confocal microscopes may reach resolutions of 180 nm laterally and 500 nm axially, however, axial resolution in depth is often impaired by spherical aberration that may occur due to refractive index mismatches. Spherical aberration results in broadening of the point-spread function (PSF, a decrease in peak signal intensity when imaging in depth and a focal shift that leads to the distortion of the image along the z-axis and thus in a scaling error. In this study, we use the novel mounting medium CFM3 (Citifluor Ltd., UK with a refractive index of 1.518 to minimize the effects of spherical aberration. This mounting medium is compatible with most common fluorochromes and fluorescent proteins. We compare its performance with established mounting media, harbouring refractive indices below 1.500, by estimating lateral and axial resolution with sub-resolution fluorescent beads. We show furthermore that the use of the high refractive index media renders the tissue transparent and improves considerably the axial resolution and imaging depth in immuno-labelled or fluorescent protein labelled fixed mouse brain tissue. We thus propose to use those novel high refractive index mounting media, whenever optimal axial resolution is required.
Equation of motion for the axial gravitational superfield
International Nuclear Information System (INIS)
Ogievetsky, V.; Sokatchev, E.
1980-01-01
Transformation properties of the axial supergravitational field variants are investigated. The equation of motion for the axial gravitational superfield is derived by direct variation of the N = 1 supergravity action. The left-hand side of this equation is a component of the torsion tensor, and the right-hand side is the supercurrent. The question about the cosmological term in supergravity is discussed
Bi-axial quartz as a stress indicator
Starkey, John
2000-03-01
Experiments confirm that stress causes quartz to become biaxial with the optical axial plane parallel to the direction of maximum applied stress. Five tectonites were studied for which published data indicate strong patterns of preferred orientation of quartz. Conoscopic investigation, using an optical universal stage, reveals that the quartz in these rocks is biaxial with the 2V as large as 22°. The optic axial planes display strong patterns of preferred orientation. In the natural tectonites the maximum stress directions deduced from the orientations of the optical axial planes cannot be correlated with the supposed tectonic framework responsible for the quartz orientation fabric. The ease with which quartz can be made biaxial experimentally suggests that the orientation of the optic axial planes may be sensitive to tectonic events which affected the rocks subsequent to the development of the quartz orientation fabrics. The analysis of the orientation of optic axial planes in biaxial quartz may provide a tool for the investigation of neotectonics.
Anomaly in the Kumakhov radiation temperature dependence at axial channeling of electrons
Energy Technology Data Exchange (ETDEWEB)
Komarov, F.F.; Telegin, V.I.; Khokonov, M.Kh.
1983-01-01
The results of numerical solution of a kinetic equation for distribution function of axially channelled electrons obtained by Belostritsky and Kumakhov at different temperatures of crystals and calculated for the determined electron distributions spectral density of radiation are given. Analysis of the obtained dependence of the number of channelled 5 GeV electrons in tungsten along the <111> axis on depth Z has revealed that 2% of incidence beam electrons have anomalously large depths of dechannelling. Ratio of electrons with large by modulus cross section energies grows at decreasing crystal temperature from 293 to 40 K and, therefore, radiation intensity increases. Two-fold increase of radiation intensity can be attained at axial channelling of 1 GeV electrons in tungsten <111> at the temperatures of the crystal equal to 40 and 293 K and its thickness equal to 220 ..mu..m.
Synthesis, fabrication and characterization of Ge/Si axial nanowire heterostructure tunnel FETs
Energy Technology Data Exchange (ETDEWEB)
Picraux, Samuel T [Los Alamos National Laboratory; Dayeh, Shadi A [Los Alamos National Laboratory
2010-01-01
Axial Ge/Si heterostructure nanowires allow energy band-edge engineering along the axis of the nanowire, which is the charge transport direction, and the realization of asymmetric devices for novel device architectures. This work reports on two advances in the area of heterostructure nanowires and tunnel FETs: (i) the realization of 100% compositionally modulated Si/Ge axial heterostructure nanowires with lengths suitable for device fabrication and (ii) the design and implementation of Schottky barrier tunnel FETs on these nanowires for high-on currents and suppressed ambipolar behavior. Initial prototype devices resulted in a current drive in excess of 100 {micro}A/{micro}m (I/{pi}D) and 10{sup 5} I{sub on}/I{sub off} ratios. These results demonstrate the potential of such asymmetric heterostructures (both in the semiconductor channel and metal-semiconductor barrier heights) for low-power and high performance electronics.
Energy Technology Data Exchange (ETDEWEB)
Tung, Wu-Hsiung, E-mail: wstong@iner.gov.tw; Lee, Tien-Tso; Kuo, Weng-Sheng; Yaur, Shung-Jung
2017-03-15
Highlights: • An optimization method for axial enrichment distribution in a BWR fuel was developed. • Block coordinate descent method is employed to search for optimal solution. • Scoping libraries are used to reduce computational effort. • Optimization search space consists of enrichment difference parameters. • Capability of the method to find optimal solution is demonstrated. - Abstract: An optimization method has been developed to search for the optimal axial enrichment distribution in a fuel assembly for a boiling water reactor core. The optimization method features: (1) employing the block coordinate descent method to find the optimal solution in the space of enrichment difference parameters, (2) using scoping libraries to reduce the amount of CASMO-4 calculation, and (3) integrating a core critical constraint into the objective function that is used to quantify the quality of an axial enrichment design. The objective function consists of the weighted sum of core parameters such as shutdown margin and critical power ratio. The core parameters are evaluated by using SIMULATE-3, and the cross section data required for the SIMULATE-3 calculation are generated by using CASMO-4 and scoping libraries. The application of the method to a 4-segment fuel design (with the highest allowable segment enrichment relaxed to 5%) demonstrated that the method can obtain an axial enrichment design with improved thermal limit ratios and objective function value while satisfying the core design constraints and core critical requirement through the use of an objective function. The use of scoping libraries effectively reduced the number of CASMO-4 calculation, from 85 to 24, in the 4-segment optimization case. An exhausted search was performed to examine the capability of the method in finding the optimal solution for a 4-segment fuel design. The results show that the method found a solution very close to the optimum obtained by the exhausted search. The number of
Relation between axial length and ocular parameters
Directory of Open Access Journals (Sweden)
Xue-Qiu Yang
2013-09-01
Full Text Available AIM: To investigatethe relation between axial length(AL, age and ocular parameters.METHODS: A total of 360 subjects(360 eyeswith emmetropia or myopia were recruited. Refraction, center corneal thickness(CCT, AL, intraocular pressure(IOPwere measured by automatic-refractor, Pachymeter, A-mode ultrasound and non-contact tonometer, respectively. Corneal curvature(CC, anterior chamber depth(ACDand white-to-white distance(WWDwere measured by Orbscan II. Three dimensional frequency domain coherent optical tomography(3D-OCTwas used to examine the retinal nerve fiber layer thickness(RNFLT. The Pearson correlation coefficient(rand multiple regression analysis were performed to evaluate the relationship between AL, age and ocular parameters.RESULTS: The average AL was 24.15±1.26mm. With elongation of the AL, spherical equivalent(SE(r=-0.742,Pr=-0.395, Pr=-0.374, Pr=0.411, Pr=0.099, P=0.060and WWD(r=0.061, P=0.252. There was also a significant correlation between AL and age(P=0.001, SE(PPPCONCLUSION: In longer eyes, there is a tendency toward myopia, a flatter cornea, a deeper ACD and a thinner RNFLT. Age is an influencing factor for the AL as well.
Nucleon axial coupling from Lattice QCD
Cheng Chang, Chia; Nicholson, Amy; Rinaldi, Enrico; Berkowitz, Evan; Garron, Nicolas; Brantley, David; Monge-Camacho, Henry; Monahan, Chris; Bouchard, Chris; Clark, M. A.; Joó, Bálint; Kurth, Thorsten; Orginos, Kostas; Vranas, Pavlos; Walker-Loud, André
2018-03-01
We present state-of-the-art results from a lattice QCD calculation of the nucleon axial coupling, gA, using Möbius Domain-Wall fermions solved on the dynamical Nf = 2 + 1 + 1 HISQ ensembles after they are smeared using the gradient-flow algorithm. Relevant three-point correlation functions are calculated using a method inspired by the Feynman-Hellmann theorem, and demonstrate significant improvement in signal for fixed stochastic samples. The calculation is performed at five pion masses of mπ {400, 350, 310, 220, 130} MeV, three lattice spacings of a {0.15, 0.12, 0.09} fm, and we do a dedicated volume study with mπL {3.22, 4.29, 5.36}. Control over all relevant sources of systematic uncertainty are demonstrated and quantified. We achieve a preliminary value of gA = 1.285(17), with a relative uncertainty of 1.33%.
Axial sheath dynamics in a plasma focus
International Nuclear Information System (INIS)
Soliman, H.M.; El-Khalafawy, T.A.; Masoud, M.M.
1990-01-01
This paper presents the result of investigation with a 10 kJ Mather type plasma focus. It is operated in hydrogen gas at ambient pressure of 0.15--1 torr and charging voltage of 8--11 kV. Radial distribution of the current sheath density with axial distance has been estimated. Plasma rotation in the expansion chamber in the absence of external magnetic field has been detected. A plasma flare from the plasma focus region propagating in the radial direction has been observed. Streak photography shows two plasma streams flowing simultaneously out of the muzzle. The mean energy of the electron beam ejected from the pinch region of the focused plasma, was measured by retarding field analyzer to be 0.32 keV. The electron temperature of the plasma focus at peak compression was determined by measuring the X-ray intensity as a function of absorber thickness at a distance of 62 cm from the focus. The electron temperature has been found to 3 keV
Nitinol stent design - understanding axial buckling.
McGrath, D J; O Brien, B; Bruzzi, M; McHugh, P E
2014-12-01
Nitinol׳s superelastic properties permit self-expanding stents to be crimped without plastic deformation, but its nonlinear properties can contribute towards stent buckling. This study investigates the axial buckling of a prototype tracheobronchial nitinol stent design during crimping, with the objective of eliminating buckling from the design. To capture the stent buckling mechanism a computational model of a radial force test is simulated, where small geometric defects are introduced to remove symmetry and allow buckling to occur. With the buckling mechanism ascertained, a sensitivity study is carried out to examine the effect that the transitional plateau region of the nitinol loading curve has on stent stability. Results of this analysis are then used to redesign the stent and remove buckling. It is found that the transitional plateau region can have a significant effect on the stability of a stent during crimping, and by reducing the amount of transitional material within the stent hinges during loading the stability of a nitinol stent can be increased. Copyright © 2014 Elsevier Ltd. All rights reserved.
Experimental Investigations on Axially and Eccentrically Loaded Masonry Walls
Keshava, Mangala; Raghunath, Seshagiri Rao
2017-12-01
In India, un-reinforced masonry walls are often used as main structural components in load bearing structures. Indian code on masonry accounts the reduction in strength of walls by using stress reduction factors in its design philosophy. This code was introduced in 1987 and reaffirmed in 1995. The present study investigates the use of these factors for south Indian masonry. Also, with the gaining popularity in block work construction, the aim of this study was to find out the suitability of these factors given in the Indian code to block work masonry. Normally, the load carrying capacity of masonry walls can be assessed in three ways, namely, (1) tests on masonry constituents, (2) tests on masonry prisms and (3) tests on full-scale wall specimens. Tests on bricks/blocks, cement-sand mortar, brick/block masonry prisms and 14 full-scale brick/block masonry walls formed the experimental investigation. The behavior of the walls was investigated under varying slenderness and eccentricity ratios. Hollow concrete blocks normally used as in-fill masonry can be considered as load bearing elements as its load carrying capacity was found to be high when compared to conventional brick masonry. Higher slenderness and eccentricity ratios drastically reduced the strength capacity of south Indian brick masonry walls. The reduction in strength due to slenderness and eccentricity is presented in the form of stress reduction factors in the Indian code. These factors obtained through experiments on eccentrically loaded brick masonry walls was lower while that of brick/block masonry under axial loads was higher than the values indicated in the Indian code. Also the reduction in strength is different for brick and block work masonry thus indicating the need for separate stress reduction factors for these two masonry materials.
Energy Technology Data Exchange (ETDEWEB)
Liu, Wenzhong; Yi, Ji; Chen, Siyu [Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Jiao, Shuliang [Department of Biomedical Engineering, Florida International University, Miami, Florida 33174 (United States); Zhang, Hao F., E-mail: hfzhang@northwestern.edu [Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208 and Department of Ophthalmology, Northwestern University, Chicago, Illinois 60611 (United States)
2015-09-15
Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31μl/min among four wild-type rats. The authors’ measured flow rates were consistent with results in the literature. Conclusions: By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.
NASA Glenn's Single-Stage Axial Compressor Facility Upgraded
Brokopp, Richard A.
2004-01-01
NASA Glenn Research Center's Single-Stage Axial Compressor Facility was upgraded in fiscal year 2003 to expand and improve its research capabilities for testing high-speed fans and compressors. The old 3000-hp drive motor and gearbox were removed and replaced with a refurbished 7000-hp drive motor and gearbox, with a maximum output speed of 21,240 rpm. The higher horsepower rating permits testing of fans and compressors with higher pressure ratio or higher flow. A new inline torquemeter was installed to provide an alternate measurement of fan and compressor efficiency, along with the standard pressure and temperature measurements. A refurbished compressor bearing housing was also installed with bidirectional rotation capability, so that a variety of existing hardware could be tested. Four new lubrication modules with backup capability were installed for the motor, gearbox, torquemeter, and compressor bearing housing, so that in case the primary pump fails, the backup will prevent damage to the rotating hardware. The combustion air supply line for the facility inlet air system was activated to provide dry air for repeatable inlet conditions. New flow conditioning hardware was installed in the facility inlet plenum tank, which greatly reduced the inlet turbulence. The new inlet can also be easily modified to accommodate 20- or 22-in.-diameter fans and compressors, so a variety of existing hardware from other facilities (such as Glenn's 9- by 15-Foot Low-Speed Wind Tunnel) can be tested in the Single-Stage Axial Compressor Facility. An exhaust line was also installed to provide bleed capability to remove the inlet boundary layer. To improve the operation and control of the facility, a new programmable logic controller (PLC) was installed to upgrade from hardwired relay logic to software logic. The PLC also enabled the usage of human-machine interface software to allow for easier operation of the facility and easier reconfiguration of the facility controls when
International Nuclear Information System (INIS)
Suwardi, S.
2001-01-01
The presented paper is a preliminary step to evaluate the effect of radial and axial distribution of power generation on thermal analysis of whole fuel pin model with large L/D ratio. The model takes into account both radial and axial distribution of power generation due to power depression and core geometry, temperature and microstructure dependent on thermal conductivity. The microstructure distribution and the gap conductance for typical steady-state situation are given for the sensitivity analysis. The temperature and thermal conductivity distribution along the radial and axial directions obtained by different power distribution is used to indicate the sensitivity of power depression and power factor on thermal aspect. The evaluation is made for one step of incremental time and steady state approach is used. The analysis has been performed using a finite element-finite difference model. The result for typical reactor fuel shows that the sensitivity is too important to be omitted in thermal model
Mean Stress Effect on the Axial Fatigue Strength of DIN 34CrNiMo6 Quenched and Tempered Steel
Directory of Open Access Journals (Sweden)
Luis Pallarés-Santasmartas
2018-03-01
Full Text Available The present study consists of a theoretical and experimental investigation of the effect of axial mean stresses on the high cycle fatigue behaviour of DIN 34CrNiMo6 high strength steel in quenched and tempered conditions. The axial S-N curves under 4 different stresses ratios were obtained. Experimental results show that increasing the value of the tension mean stresses gradually reduces the axial stress amplitude the material can withstand without failure. Moreover, the compressive mean stresses show a beneficial effect in terms of the axial fatigue strength, resulting in a non-symmetrical Haigh diagram. A historic review of the axial mean stress effect is presented, showing the shape of the Haigh diagrams for ductile metals and presenting the most-known empirical and physical theories. The results for this steel are compared with the physical theories of Findley based on the critical plane; the Froustey’s and Marin’s methods, based on energetic theories; and the Crossland invariants method based on the Gough’s theory of fatigue damage. Taking into account the experimental results, a physical fatigue function based on energetic considerations is proposed. Its application to the fatigue case with mean stresses can be interpreted in terms of a balance of elastic energies of distortion and volume change. Macro-analyses of specimen fracture appearance were conducted in order to obtain the fracture characteristics for different mean stress values.
Conservative axial burnup distributions for actinide-only burnup credit
International Nuclear Information System (INIS)
Kang, C.; Lancaster, D.
1997-11-01
Unlike the fresh fuel approach, which assumes the initial isotopic compositions for criticality analyses, any burnup credit methodology must address the proper treatment of axial burnup distributions. A straightforward way of treating a given axial burnup distribution is to segment the fuel assembly into multiple meshes and to model each burnup mesh with the corresponding isotopic compositions. Although this approach represents a significant increase in modeling efforts compared to the uniform average burnup approach, it can adequately determine the reactivity effect of the axial burnup distribution. A major consideration is what axial burnup distributions are appropriate for use in light of many possible distributions depending on core operating conditions and histories. This paper summarizes criticality analyses performed to determine conservative axial burnup distributions. The conservative axial burnup distributions presented in this paper are included in the Topical Report on Actinide-Only Burnup Credit for Pressurized Water Reactor Spent Nuclear Fuel Packages, Revision 1 submitted in May 1997 by the US Department of Energy (DOE) to the US Nuclear Regulatory Commission (NRC). When approved by NRC, the conservative axial burnup distributions may be used to model PWR spent nuclear fuel for the purpose of gaining actinide only burnup credit
Axial elongation following prolonged near work in myopes and emmetropes.
Woodman, Emily C; Read, Scott A; Collins, Michael J; Hegarty, Katherine J; Priddle, Scott B; Smith, Josephine M; Perro, Judd V
2011-05-01
To investigate the influence of a period of sustained near work upon axial length in groups of emmetropes (EMM) and myopes. Forty young adult subjects (20 myopes and 20 emmetropes) were recruited for the study. Myopes were further classified as early onset (EOM), late onset (LOM), stable (SM) or progressing (PM) subgroups. Axial length was measured with the IOLMaster instrument before, immediately after and then again 10 min after a continuous 30 min near task of 5 D accommodation demand. Measures of distance objective refraction were also collected. Significant changes in axial length were observed immediately following the near task. EOM axial length elongated on average by 0.027±0.021 mm, LOM by 0.014±0.020 mm, EMM by 0.010±0.015 mm, PM by 0.031±0.022 mm and SM by 0.014±0.018 mm. At the conclusion of the 10 min regression period, axial length measures were not significantly different from baseline values. Axial elongation was observed following a prolonged near task. Both EOM and PM groups showed increases in axial length that were significantly greater than emmetropes.
Tănase Alin-Eliodor
2014-01-01
This article focuses on computing techniques starting from trial balance data regarding financial key ratios. There are presented activity, liquidity, solvency and profitability financial key ratios. It is presented a computing methodology in three steps based on a trial balance.
Dispositivos de asistencia ventricular de tipo axial
Directory of Open Access Journals (Sweden)
Albert Miralles Cassina
2009-04-01
Full Text Available El uso de dispositivos de asistencia ventricular se ha ido extendiendo en las últimas décadas. La mejora de los resultados ha ido acompañada del diseño de nuevos aparatos más pequeños y eficientes como son las bombas de flujo axial. las características técnicas básicas de estos dispositivos se hallan en la generación de un flujo continuo unidireccional conseguido mediante sistemas de turbina que obtienen su alimentación de una fuente eléctrica. Las ventajas principales de estos dispositivos son: su facilidad de implantación por su tamaño reducido, su prolongada durabilidad gracias a su sencillo diseño y su eficiencia energética al utilizar energía eléctrica. Su utilidad se ha podido demostrar en diferentes indicaciones de asistencia circulatoria mecánica, como en el caso de puente al trasplante o dispositivo de recuperación miocárdica, si bien donde radica más interés es en su uso como sistemas de asistencia circulatoria mecánica definitiva. Existe una variedad de modelos de diversos diseños. Son dispositivos que permiten soporte normalmente univentricular izquierdo, que se implantan en el tórax con cánula de entrada a nivel ventricular y cánula de salida a nivel aórtico. En este artículo se efectúa una descripción de los principales sistemas disponibles en la actualidad, comentando las características técnicas, ventajas e inconvenientes y un resumen de la experiencia existente.
Radial loads and axial thrusts on centrifugal pumps
International Nuclear Information System (INIS)
Anon.
1986-01-01
The proceedings of a seminar organised by the Power Industries Division of the IMechE are presented in this text. Complete contents: Review of parameters influencing hydraulic forces on centrifugal impellers; The effect of fluid forces at various operation conditions on the vibrations of vertical turbine pumps; A review of the pump rotor axial equilibrium problem - some case studies; Dynamic hydraulic loading on a centrifugal pump impeller; Experimental research on axial thrust loads of double suction centrifugal pumps; A comparison of pressure distribution and radial loads on centrifugal pumps; A theoretical and experimental investigation of axial thrusts within a multi-stage centrifugal pump
Measurement for cobalt target activity and its axial distribution
International Nuclear Information System (INIS)
Li Xingyuan; Chen Zigen.
1985-01-01
Cobalt target activity and its axial distribution are measured in process of producing radioactive isotopes 60 Co by irradiation in HFETR. Cobalt target activity is obtained with measured data at 3.60 m and 4.60 m, relative axial distribution of cobalt target activity is obtained with one at 30 cm, and axial distribution of cobalt target activity(or specific activity) is obtained with both of data. The difference between this specific activity and measured result for 60 Co teletherapy sources in the end is less than +- 5%
Axial weak currents in the Wess-Zumino term
International Nuclear Information System (INIS)
Fujikawa, Kazuo.
1985-03-01
The conventional axial gauging of the Wess-Zumino term leads to the results which do not necessarily agree with the expectations on the basis of quark level Ward-Takahashi identities. This discrepancy arises from the fact that the quark level anomalous identities reflect the short distance structure of QCD, whereas the gauging of the Wess-Zumino term reflects the axial symmetry in the spontaneously broken chiral phase. The low energy theorem for axial weak fields is not sharply defined, in contrast to the case of vector fields where no such complications arise. (author)
Directory of Open Access Journals (Sweden)
Yasuyuki Nishi
2016-01-01
Full Text Available We proposed a portable and ultra-small axial flow hydraulic turbine that can generate electric power comparatively easily using the low head of open channels such as existing pipe conduits or small rivers. In addition, we proposed a simple design method for axial flow runners in combination with the conventional one-dimensional design method and the design method of axial flow velocity uniformization, with the support of three-dimensional flow analysis. Applying our design method to the runner of an ultra-small axial flow hydraulic turbine, the performance and internal flow of the designed runner were investigated using CFD analysis and experiment (performance test and PIV measurement. As a result, the runners designed with our design method were significantly improved in turbine efficiency compared to the original runner. Specifically, in the experiment, a new design of the runner achieved a turbine efficiency of 0.768. This reason was that the axial component of absolute velocity of the new design of the runner was relatively uniform at the runner outlet in comparison with that of the original runner, and as a result, the negative rotational flow was improved. Thus, the validity of our design method has been verified.
Rawat, Roopa; Agrawal, Neha; Patil, Nilesh S.
2017-01-01
Since 1984 the diagnosis of ankylosing spondylitis (AS) has been based upon the modified New York (mNY) criteria with mandatory presence of radiographic sacroiliitis, without which the diagnosis is not tenable. However, it may take years or decades for radiographic sacroiliitis to develop delaying the diagnosis for long periods. It did not matter in the past because no effective treatment was available. However, with the availability of a highly effective treatment, namely, tumour necrosis factor-α inhibitors (TNFi), the issue of early diagnosis of AS acquired an urgency. The Assessment of SpondyloArthritis International Society (ASAS) classification criteria published in 2009 was a significant step towards this goal. These criteria described an early stage of the disease where sacroiliitis was demonstrable only on MRI but not on standard radiograph. Therefore, this stage of the disease was labelled “nonradiographic axial SpA” (nr-axSpA). But questions have been raised if, in search of early diagnosis, specificity was compromised. The Federal Drug Administration (FDA, USA) withheld approval for the use of TNFi in patients with nr-axSpA because of issues related to the specificity of these criteria. This review attempts to clarify some of these aspects of the nr-axSpA-AS relationship and also tries to answer the question whether ASAS classifiable radiographic axial spondyloarthritis (r-axSpA) term can be interchangeably used with the term AS. PMID:28555158
Cladding axial elongation models for FRAP-T6
International Nuclear Information System (INIS)
Shah, V.N.; Carlson, E.R.; Berna, G.A.
1983-01-01
This paper presents a description of the cladding axial elongation models developed at the Idaho National Engineering Laboratory (INEL) for use by the FRAP-T6 computer code in analyzing the response of fuel rods during reactor transients in light water reactors (LWR). The FRAP-T6 code contains models (FRACAS-II subcode) that analyze the structural response of a fuel rod including pellet-cladding-mechanical-interaction (PCMI). Recently, four models were incorporated into FRACAS-II to calculate cladding axial deformation: (a) axial PCMI, (b) trapped fuel stack, (c) fuel relocation, and (d) effective fuel thermal expansion. Comparisons of cladding axial elongation measurements from two experiments with the corresponding FRAP-T6 calculations are presented
The relation between anomalous magnetic moment and axial anomaly
International Nuclear Information System (INIS)
Teryaev, O.V.
1990-12-01
The conservation of total angular momentum of spinor particle leads to a simple relation between the famous Schwinger and Adler coefficients determining axial anomaly and anomalous magnetic moment, respectively. (author). 8 refs, 1 fig
Defining active sacroiliitis on MRI for classification of axial spondyloarthritis
DEFF Research Database (Denmark)
Lambert, Robert G W; Bakker, Pauline A C; van der Heijde, Désirée
2016-01-01
OBJECTIVES: To review and update the existing definition of a positive MRI for classification of axial spondyloarthritis (SpA). METHODS: The Assessment in SpondyloArthritis International Society (ASAS) MRI working group conducted a consensus exercise to review the definition of a positive MRI...... for inclusion in the ASAS classification criteria of axial SpA. Existing definitions and new data relevant to the MRI diagnosis and classification of sacroiliitis and spondylitis in axial SpA, published since the ASAS definition first appeared in print in 2009, were reviewed and discussed. The precise wording....... CONCLUSION: The definition of a positive MRI for classification of axial SpA should continue to primarily depend on the imaging features of 'active sacroiliitis' until more data are available regarding MRI features of structural damage in the sacroiliac joint and MRI features in the spine and their utility...
The geometrical theory of diffraction for axially symmetric reflectors
DEFF Research Database (Denmark)
Rusch, W.; Sørensen, O.
1975-01-01
The geometrical theory of diffraction (GTD) (cf. [1], for example) may be applied advantageously to many axially symmetric reflector antenna geometries. The material in this communication presents analytical, computational, and experimental results for commonly encountered reflector geometries...
Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project
National Aeronautics and Space Administration — We propose to demonstrate key elements of feasibility for a high speed automated time domain terahertz computed axial tomography (TD-THz CT) non destructive...
Pole prescription in axial gauge at finite temperature
Kreuzer, Maximilian; Nachbagauer, Herbert
1991-11-01
We establish Yang-Mills theory at finite temperature in axial gauge. We encounter the breakdown of the Hata-Kugo expression for the partition function in the special choice of temporal axial gauge. For n ≠ 0 the finite temperature propagator is calculated in both the imaginary time formalism and the real time formalism. In the latter we recover the Leibbrandt-Mandelstam prescription in the lijit T→0. As a check we calculate the mean energy to lowest order.
Pole prescription in axial gauge at finite temperature
Energy Technology Data Exchange (ETDEWEB)
Kreuzer, M.; Nachbagauer, H. (Technische Univ., Vienna (Austria). Inst. fuer Theoretische Physik)
1991-11-14
We establish Yang-Mills theory at finite temperature in axial gauge. We encounter the breakdown of the Hata-Kugo expression for the partition function in the special choice of temporal axial gauge. For n {ne} 0 the finite temperature propagator is calculated in both the imaginary time formalism and the real time formalism. In the latter we recover the Leibbrandt-Mandelstam prescription in the limit T {yields} 0. As a check we calculate the mean energy to lowest order. (orig.).
Axial myopia in computed and magnetic resonance tomography
Energy Technology Data Exchange (ETDEWEB)
Beyer-Enke, S.A.; Goerich, J.; Gamroth, A.
1987-08-01
The case of a 44-year old woman suffering from amblyopia on the left eye with unilateral proptosis caused by axial (progressive) myopia is presented. The clinical and radiological findings were discussed in reference to the literature. The diagnosis was established by ruling out neoplastic, inflammatory or endocrine causes for the exophtalmos. CT and MR scans revealed an enlarged left globe without evidence of orbital masses. The findings were regarded as typical for the diagnosis at axial myopia.
Flutter of a fan blade in supersonic axial flow
Kielb, Robert E.; Ramsey, John K.
1988-01-01
An application of a simple aeroelastic model to an advanced supersonic axial flow fan is presented. Lane's cascade theory is used to determine the unsteady aerodynamic loads. Parametric studies are performed to determine the effects of mode coupling, Mach number, damping, pitching axis location, solidity, stagger angle, and mistuning. The results show that supersonic axial flow fan and compressor blades are susceptible to a strong torsional mode flutter having critical reduced velocities which can be less than one.
On solutions of boundary value problems for model of axially symmetric quantum dots
International Nuclear Information System (INIS)
Gusev, A.A.; Chvluunbaatar, O.; Vinitsky, S.I.; Dvoyan, K.G.; Kazaryan, E.M.; Sarkisyan, H.A.
2010-01-01
Full text: (author)In the framework of effective mass approximation we have considered solutions of boundary value problems with separated and nonseparated variables for models of quantum dots with axial-symmetric potentials of harmonic oscillators and confinement potentials with infinite and finite walls. For considered problems we have made comparisons of levels with low energy of discrete spectra and eigenfunctions nodes by using exact and adiabatic classification of states. Critical values of the spheroidal aspect ratio, at which the discrete spectrum of models with finite-wall potentials is transformed into a continuous one in strong dimensional quantization regime, were revealed
Axial loading cross screw fixation for the Austin bunionectomy.
Rigby, Ryan B; Fallat, Lawrence M; Kish, John P
2011-01-01
The Austin procedure has become a common method of osteotomy for the correction of hallux abductovalgus when indicated. The V-type configuration is intrinsically stable but not without complications. One complication encountered is rotation and/or displacement of the capital fragment. We present the use of an axial loading screw in conjunction with a dorsally placed compression screw. The benefit to this technique lies in the orientation of the axial loading screw, because it is directed to resist the ground reactive forces while also providing a second point of fixation in a crossing screw design. In a head-to-head biomechanical comparison, we tested single dorsal screw fixation versus double screw fixation, including both the dorsal and the axial loading screws in 10 metatarsal Sawbones(®) (Pacific Research Laboratories Inc, Vashon, WA). Five metatarsals received single dorsal screw fixation and five received the dorsal screw and the additional axial loading screw. The metatarsals were analyzed on an Instron compression device for comparison; 100% of the single screw fixation osteotomies failed with compression at an average peak load of 205 N. Four of five axial loading double screw fixation osteotomies did not fail. This finding suggests that the addition of an axial loading screw providing cross screw orientation significantly increases the stability of the Austin osteotomy, ultimately decreasing the likelihood of displacement encountered in the surgical repair of hallux abductovalgus. Copyright © 2011 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.
Reactive control of subsonic axial fan noise in a duct.
Liu, Y; Choy, Y S; Huang, L; Cheng, L
2014-10-01
Suppressing the ducted fan noise at low frequencies without varying the flow capacity is still a technical challenge. This study examines a conceived device consisting of two tensioned membranes backed with cavities housing the axial fan for suppression of the sound radiation from the axial fan directly. The noise suppression is achieved by destructive interference between the sound fields from the axial fan of a dipole nature and sound radiation from the membrane via vibroacoustics coupling. A two-dimensional model with the flow effect is presented which allows the performance of the device to be explored analytically. The air flow influences the symmetrical behavior and excites the odd in vacuo mode response of the membrane due to kinematic coupling. Such an asymmetrical effect can be compromised with off-center alignment of the axial fan. Tension plays an important role to sustain the performance to revoke the deformation of the membrane during the axial fan operation. With the design of four appropriately tensioned membranes covered by a cylindrical cavity, the first and second blade passage frequencies of the axial fan can be reduced by at least 20 dB. The satisfactory agreement between experiment and theory demonstrates that its feasibility is practical.
Energy Technology Data Exchange (ETDEWEB)
Castillo, A.; Torres, M.; Ortiz, J. J.; Perusquia, R.; Hernandez, J. L.; Montes, J. L. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: jacm@nuclear.inin.mx
2008-07-01
In the present work the preliminary results were obtained with the zoctli system whose purpose is the axial design of assembly of nuclear fuel under certain considerations. For the mentioned design well-know cells were already used and that they have been proven in diverse cycles of operation in the nuclear power plant of Laguna Verde. The design contemplates fuels assemblies of 10x10 and with 2 water channels. The assembly was distributed in 6 axial zones according to its structure. In order to take to end the optimization is was used the well-known technique like Path relinking and to find the group of previous solutions required by this technique uses the technical Taboo search. In order to work with Path relinking, 5 trajectories was taken in to account from a set of 5 previous solutions generated with theTaboo search, the update of the group of solutions is carried out in dynamic form. In the case of the Taboo search it was used a list of variable size, it was implement an aspiration approach, it was used the vector of frequencies and due to the cost of the evaluation of the objective function, only it was review 5% of the vicinity. For the objective function was considered the limit thermal, the axial profile of power, the effective multiplication factor and the margin of having turned off in cold. In order to prove the design system, it was used a balance cycle with a value of reference of 0.9928 for the effective multiplication factor that is equivalent to a produced energy of 10896 MWd/TU at the end of operation to full power. The designed assemblies were placed both in one of lots different from fresh assemblies on which it counts the referred cycle. At the end one a comparison with the results obtained with other techniques and under similar conditions is made. The results obtained until the moment show an appropriate performance of the system. It is possible to indicate that a small inconvenient is the amount of consumed resources of calculation during
Braem, André; Joram, C; Séguinot, Jacques; Weilhammer, P; De Leo, R; Nappi, E; Lustermann, W; Schinzel, D; Johnson, I; Renker, D; Albrecht, S
2007-01-01
We describe a novel method to extract the axial coordinate from a matrix of long axially oriented crystals, which is based on wavelength shifting plastic strips. The method allows building compact 3-D axial gamma detector modules for PET scanners with excellent 3-dimensional spatial, timing and energy resolution while keeping the number of readout channels reasonably low. A voxel resolution of about 10 mm3 is expected. We assess the performance of the method in two independent ways, using classical PMTs and G-APDs to read out the LYSO (LSO) scintillation crystals and the wavelength shifting strips. We observe yields in excess of 35 photoelectrons from the strips for a 511 keV gamma and reconstruct the axial coordinate with a precision of about 2.5 mm (FWHM).
International Nuclear Information System (INIS)
Dinh, Cong-Truong; Ma, Sang-Bum; Kim, Kwang Yong
2017-01-01
In this study, stator shroud injection in a single-stage transonic axial compressor is proposed. A parametric study of the effect of stator shroud injection on aerodynamic performances was conducted using the three-dimensional Reynolds-averaged Navier-Stokes equations. The curvature, length, width, and circumferential angle of the stator shroud injector and the air injection mass flow rate were selected as the test parameters. The results of the parametric study show that the aerodynamic performances of the single-stage transonic axial compressor were improved by stator shroud injection. The aerodynamic performances were the most sensitive to the injection mass flow rate. Further, the total pressure ratio and adiabatic efficiency were the maximum when the ratio of circumferential angle was 10%.
Energy Technology Data Exchange (ETDEWEB)
Dinh, Cong-Truong; Ma, Sang-Bum; Kim, Kwang Yong [Inha Univ., Incheon (Korea, Republic of)
2017-01-15
In this study, stator shroud injection in a single-stage transonic axial compressor is proposed. A parametric study of the effect of stator shroud injection on aerodynamic performances was conducted using the three-dimensional Reynolds-averaged Navier-Stokes equations. The curvature, length, width, and circumferential angle of the stator shroud injector and the air injection mass flow rate were selected as the test parameters. The results of the parametric study show that the aerodynamic performances of the single-stage transonic axial compressor were improved by stator shroud injection. The aerodynamic performances were the most sensitive to the injection mass flow rate. Further, the total pressure ratio and adiabatic efficiency were the maximum when the ratio of circumferential angle was 10%.
Axial Lengths in Children with Recessive Cornea Plana.
Al Hazimi, Amro; Khan, Arif O
2015-06-01
While flat keratometry contributes to the hyperopia and associated refractive accommodative esotropia that is part of recessive cornea plana, whether or not axial lengths are abnormally short in the disease is unclear. In this study we assess this possibility. Prospective (2010-2012) axial length measurement (IOLmaster; Carl Zeiss, Oberkochen, Germany) of affected right eyes and comparison to right eyes with refractive accommodative esotropia only. Keratometry and refraction were also performed. For eight affected right eyes (age 10-12 years; seven families) axial length ranged from 21.46-24.80 mm (mean 23.34). Best corrected visual acuity ranged from 20/25 to 20/50, keratometry from 25.33-39.80 diopters (D) [mean 31.80], and refraction from +2.00 to +14.00 D (mean +7.22). For 50 control right eyes (age 4-12 years), axial length ranged from 19.87-23.66 mm (mean 21.6). Best-corrected visual acuity was 20/25 or better, keratometry ranged from 39.81-46.25 D (mean 42.42), and refraction from +2.25 to +8.00 D (mean 4.71). Axial lengths were longer in the affected group (2-tailed unpaired t-test p value 0.000005) despite greater hyperopia (2-tailed unpaired t-test p value 0.001). Despite greater hyperopia, axial lengths were longer in eyes with recessive cornea plana, evidence that axial lengths are not shortened by the disease. Keratometry in children with cornea plana was below the range of controls and was the major factor underlying the phenotype's hyperopia.
Mathieson, Haley Aaron
This thesis investigates experimentally and analytically the structural performance of sandwich panels composed of glass fibre reinforced polymer (GFRP) skins and a soft polyurethane foam core, with or without thin GFRP ribs connecting skins. The study includes three main components: (a) out-of-plane bending fatigue, (b) axial compression loading, and (c) in-plane bending of sandwich beams. Fatigue studies included 28 specimens and looked into establishing service life (S-N) curves of sandwich panels without ribs, governed by soft core shear failure and also ribbed panels governed by failure at the rib-skin junction. Additionally, the study compared fatigue life curves of sandwich panels loaded under fully reversed bending conditions (R=-1) with panels cyclically loaded in one direction only (R=0) and established the stiffness degradation characteristics throughout their fatigue life. Mathematical models expressing fatigue life and stiffness degradation curves were calibrated and expanded forms for various loading ratios were developed. Approximate fatigue thresholds of 37% and 23% were determined for non-ribbed panels loaded at R=0 and -1, respectively. Digital imaging techniques showed significant shear contribution significantly (90%) to deflections if no ribs used. Axial loading work included 51 specimens and examined the behavior of panels of various lengths (slenderness ratios), skin thicknesses, and also panels of similar length with various rib configurations. Observed failure modes governing were global buckling, skin wrinkling or skin crushing. In-plane bending involved testing 18 sandwich beams of various shear span-to-depth ratios and skin thicknesses, which failed by skin wrinkling at the compression side. The analytical modeling components of axially loaded panels include; a simple design-oriented analytical failure model and a robust non-linear model capable of predicting the full load-displacement response of axially loaded slender sandwich panels
Geomorphological impact of an axial-flow hydrokinetic turbine model
Hill, C.; Chamorro, L. P.; Sotiropoulos, F.; Guala, M.
2012-12-01
MHK devices in river or tidal environments are expected to impact the local geomorphology in the short and long terms, yet to what extent is unknown. A series of experiments in the SAFL main channel were performed on an erodible sediment layer at the threshold of motion aimed at quantifying the local effect of an axial-flow turbine model on erosional and depositional processes. Full planimetric, time resolved measurements of bed elevations z = z(x, y, t) were obtained using a 2D sheet laser scanner mounted on a computer controlled data acquisition carriage. Measurement resolution was 2 mm x 2 mm in the streamwise (x) and spanwise (y) directions, and approximately 70 s temporally. Approximately 180 topographic scans were obtained in about 3.8 hours while simultaneously monitoring mean approach velocities using an acoustic Doppler profiler located approximately 2 rotor diameters, dT, upstream of the turbine. Three synchronized acoustic Doppler velocimeters (ADVs) located 6dT downstream of the turbine at locations coincident with the turbine axis of symmetry and at the lateral blade tips at hub height obtained instantaneous three component velocity measurements u, v, w in the wake of the turbine. The 1:10 scale axial-flow hydrokinetic turbine model operated at a constant tip speed ratio ωdT/2U = 6.3 while measuring instantaneous torque (ω is the rotor angular velocity and U is the mean incoming velocity at the hub height). The sediment layer consisted of coarse sand with mean diameter d50 = 1.8 mm. Using laser scanning measurements, the sediment layer was observed to be stable under the given hydraulic conditions (total discharge of Qw = 1.765 m3s-1 and water depth of h = 1.15 m) during the baseline case (no turbine), ensuring that the mean shear stress was below the critical value for the duration of the experiment. Maintaining the same flow conditions, three additional experiments were performed: a) effect of turbine support (base and tower) only, b) effect of
Continuous millennial decrease of the Earth's magnetic axial dipole
Poletti, Wilbor; Biggin, Andrew J.; Trindade, Ricardo I. F.; Hartmann, Gelvam A.; Terra-Nova, Filipe
2018-01-01
Since the establishment of direct estimations of the Earth's magnetic field intensity in the first half of the nineteenth century, a continuous decay of the axial dipole component has been observed and variously speculated to be linked to an imminent reversal of the geomagnetic field. Furthermore, indirect estimations from anthropologically made materials and volcanic derivatives suggest that this decrease began significantly earlier than direct measurements have been available. Here, we carefully reassess the available archaeointensity dataset for the last two millennia, and show a good correspondence between direct (observatory/satellite) and indirect (archaeomagnetic) estimates of the axial dipole moment creating, in effect, a proxy to expand our analysis back in time. Our results suggest a continuous linear decay as the most parsimonious long-term description of the axial dipole variation for the last millennium. We thus suggest that a break in the symmetry of axial dipole moment advective sources occurred approximately 1100 years earlier than previously described. In addition, based on the observed dipole secular variation timescale, we speculate that the weakening of the axial dipole may end soon.
Amphiregulin Antibody and Reduction of Axial Elongation in Experimental Myopia
Directory of Open Access Journals (Sweden)
Wen Jun Jiang
2017-03-01
Full Text Available To examine the mechanism of ocular axial elongation in myopia, guinea pigs (age: 2–3 weeks which either underwent unilateral or bilateral lens-induced myopization (group 1 or which were primarily myopic at baseline (group 2 received unilateral intraocular injections of amphiregulin antibody (doses: 5, 10, or 15 μg three times in intervals of 9 days. A third group of emmetropic guinea pigs got intraocular unilateral injections of amphiregulin (doses: 0.25, 0.50 or 1.00 ng, respectively. In each group, the contralateral eyes received intraocular injections of Ringer's solution. In intra-animal inter-eye comparison and intra-eye follow-up comparison in groups 1 and 2, the study eyes as compared to the contralateral eyes showed a dose-dependent reduction in axial elongation. In group 3, study eyes and control eyes did not differ significantly in axial elongation. Immunohistochemistry revealed amphiregulin labelling at the retinal pigment epithelium in eyes with lens-induced myopization and Ringer's solution injection, but not in eyes with amphiregulin antibody injection. Intraocular injections of amphiregulin-antibody led to a reduction of lens-induced axial myopic elongation and of the physiological eye enlargement in young guinea pigs. In contrast, intraocularly injected amphiregulin in a dose of ≤1 ng did not show a significant effect. Amphiregulin may be one of several essential molecular factors for axial elongation.
Analysis of axial compressive loaded beam under random support excitations
Xiao, Wensheng; Wang, Fengde; Liu, Jian
2017-12-01
An analytical procedure to investigate the response spectrum of a uniform Bernoulli-Euler beam with axial compressive load subjected to random support excitations is implemented based on the Mindlin-Goodman method and the mode superposition method in the frequency domain. The random response spectrum of the simply supported beam subjected to white noise excitation and to Pierson-Moskowitz spectrum excitation is investigated, and the characteristics of the response spectrum are further explored. Moreover, the effect of axial compressive load is studied and a method to determine the axial load is proposed. The research results show that the response spectrum mainly consists of the beam's additional displacement response spectrum when the excitation is white noise; however, the quasi-static displacement response spectrum is the main component when the excitation is the Pierson-Moskowitz spectrum. Under white noise excitation, the amplitude of the power spectral density function decreased as the axial compressive load increased, while the frequency band of the vibration response spectrum increased with the increase of axial compressive load.
Development and Testing of an Axial Halbach Magnetic Bearing
Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.
2006-01-01
The NASA Glenn Research Center has developed and tested a revolutionary Axial Halbach Magnetic Bearing. The objective of this work is to develop a viable non-contact magnetic thrust bearing utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help to reduce harmful emissions, reduce the Nation s dependence on fossil fuels and mitigate many of the concerns and limitations encountered in conventional axial bearings such as bearing wear, leaks, seals and friction loss. The Axial Halbach Magnetic Bearing is inherently stable and requires no active feedback control system or superconductivity as required in many magnetic bearing designs. The Axial Halbach Magnetic Bearing is useful for very high speed applications including turbines, instrumentation, medical systems, computer memory systems, and space power systems such as flywheels. Magnetic fields suspend and support a rotor assembly within a stator. Advanced technologies developed for particle accelerators, and currently under development for maglev trains and rocket launchers, served as the basis for this application. Experimental hardware was successfully designed and developed to validate the basic principles and analyses. The report concludes that the implementation of Axial Halbach Magnetic Bearings can provide significant improvements in rotational system performance and reliability.
Modeling Effects of Axial Extension on Arterial Growth and Remodeling
Valentín, A.; Humphrey, J.D.
2013-01-01
Diverse mechanical perturbations elicit arterial growth and remodeling responses that appear to optimize structure and function so as to achieve mechanical homeostasis. For example, it is well known that functional adaptations to sustained changes in transmural pressure and blood flow primarily affect wall thickness and caliber to restore circumferential and wall shear stresses toward normal. More recently, however, it has been shown that changes in axial extension similarly prompt dramatic cell and matrix reorganization and turnover, resulting in marked changes in unloaded geometry and mechanical behavior that presumably restore axial stress toward normal. Because of the inability to infer axial stress from in vivo measurements, simulations are needed to examine this hypothesis and to guide the design of future experiments. In this paper, we show that a constrained mixture model predicts salient features of observed responses to step increases in axial extension, including marked increases in fibrous constituent production, leading to a compensatory lengthening that restores original mechanical behavior. Because axial extension can be modified via diverse surgical procedures, including bypass operations and exploited in tissue regeneration research, there is a need for increased attention to this important aspect of arterial biomechanics and mechanobiology. PMID:19649667
Operating characteristics of heavy loaded cylindrical journal bearing with variable axial profile
Directory of Open Access Journals (Sweden)
Stanislaw Strzelecki
2005-12-01
Full Text Available During the operation of turbounit its bearings displace as a result of heat elongation of bearings supports. It changes the static deflection line of rotor determined during assembly of the turbounit, causing an increase in the stresses on the bearing edges and a decrease in the dynamic state of the machine. One of possibilities to avoid the edge stresses is to apply the bearings with variable axial profile, e.g. hyperboloidal, convex profile in the axial cross-section of bearing. Application of journal bearings with hyperboloidal profile allows to extend the bearing operation range without the stress concentration on the edges of bush. These bearings successfully carry the extreme load in conditions of misaligned axis of journal and the bush eliminating the necessity of using self-aligning bearings. Operating characteristics of bearing include the resulting force, attitude angle, oil film pressure and temperature distributions, minimum oil film thickness, maximum oil film temperature. In literature there is a lack of data on the operating characteristics of heavy loaded hyperboloidal journal bearings operating at the conditions of adiabatic oil film and static equilibrium position of the journal. For the hyperboloidal bearing the operating characteristics have been obtained. Different values of length to diameter ratio, assumed shape and inclination ratio coefficients have been assumed. Iterative solution of the Reynolds', energy and viscosity equations was applied. Adiabatic oil film, laminar flow in the bearing gap as well as aligned and misaligned orientation of journal in the bush were considered.
Yin, Jun; Coutris, Nicole; Huang, Yong
2010-11-16
Hollow fiber membranes (HFMs) are extensively used in different industrial applications. Under some controlled fabrication conditions, axially aligned grooves can be formed on the HFM inner surface during typical immersion precipitation-based phase inversion fabrication processes. Such grooved HFMs are found to be promising for nerve repair and regeneration. The axially aligned grooves appearing on the inner surface of the membrane are considered as hydrodynamic instability patterns. During the immersion precipitation process, a transfer of solvent takes place across the interface between a polymer solution and a nonsolvent. This solvent transfer induces gradients of interfacial tension that are considered to be the driving mechanism for Marangoni instability. The onset of the stationary instability is studied by means of a linear instability theory, and the critical and maximum wavenumbers are determined and discussed in terms of the dimensionless groups characterizing the system: viscosity ratio, diffusivity ratio, Schmidt number, crispation number, adsorption number, Marangoni number, and the polymer bulk concentration. A good agreement is found between the predicted wavelength of the most dangerous wave and the experimental groove width. Consequently, solutal Marangoni instability can explain the groove formation mechanism in HFM fabrication.
Starch/PCL composite nanofibers by co-axial electrospinning technique for biomedical applications.
Komur, B; Bayrak, F; Ekren, N; Eroglu, M S; Oktar, F N; Sinirlioglu, Z A; Yucel, S; Guler, O; Gunduz, O
2017-03-29
In this study, starch and polycaprolactone (PCL), composite nanofibers were fabricated by co-axial needle electrospinning technique. Processing parameters such as polymer concentration, flow rate and voltage had a marked influence on the composite fiber diameter. Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), mechanical and physical properties (such as density, viscosity and electrical conductivity) of the composite fibres were evaluated. Moreover, a cell culture test was performed in order to determine their cytotoxicity for wound dressing application. The effect of starch ratio in the solution on the properties and morphological structure of the fibers produced was presented. With lower starch concentration values, the fibers have greater ultimate tensile strength characteristic (mostly 4 and 5 wt%). According to SEM results, it can be figured out that the nanofibers fabricated have good spinnability and morphology. The mean diameter of the fibers is about 150 nm. According to results of cell culture study, the finding can be determined that the increase of starch in the fiber also increases the cell viability. Composite nanofibers of starch/PCL have been prepared using a co-axial needle electrospinning technique. PCL was successfully encapsulated within starch. Fiber formation was observed for different ratio of starch. With several test, analysis and measurement performed, some important parameters such as quality and effectuality of each fiber obtained for wound dressing applications were discussed in detail.
DEFF Research Database (Denmark)
Svendsen, Anders Jørgen; Holmskov, U; Bro, Peter
1995-01-01
hitherto unnoted differences between controls and patients with either rheumatoid arthritis or systemic lupus erythematosus. For this we use simple, but unconventional, graphic representations of the data, based on difference plots and ratio plots. Differences between patients with Burkitt's lymphoma...... and systemic lupus erythematosus from another previously published study (Macanovic, M. and Lachmann, P.J. (1979) Clin. Exp. Immunol. 38, 274) are also represented using ratio plots. Our observations indicate that analysis by regression analysis may often be misleading....
Calculation of the heavy-hadron axial couplings g1, g2, and g3 using lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Will Detmold, David Lin, Stefan Meinel
2012-06-01
In a recent paper [arXiv:1109.2480] we have reported on a lattice QCD calculation of the heavy-hadron axial couplings g{sub 1}, g{sub 2}, and g{sub 3}. These quantities are low-energy constants of heavy-hadron chiral perturbation theory (HH{chi}PT) and are related to the B*B{pi}, {Sigma}{sub b}*{Sigma}{sub b}{pi}, and {Sigma}{sub b}{sup (*)}{Lambda}{sub b}{pi} couplings. In the following, we discuss important details of the calculation and give further results. To determine the axial couplings, we explicitly match the matrix elements of the axial current in QCD with the corresponding matrix elements in HH{chi}PT. We construct the ratios of correlation functions used to calculate the matrix elements in lattice QCD, and study the contributions from excited states. We present the complete numerical results and discuss the data analysis in depth. In particular, we demonstrate the convergence of SU(4|2) HH{chi}PT for the axial current matrix elements at pion masses up to about 400 MeV and show the impact of the nonanalytic loop contributions. Finally, we present additional predictions for strong and radiative decay widths of charm and bottom baryons.
Energy Technology Data Exchange (ETDEWEB)
Forsyth, R.S.; Blackadder, W.H.; Ronqvist, N.
1967-02-15
In the gamma spectrometric determination of burn-up the use of a single fission product as a monitor of the specimen fission rate is subject to errors caused by activity saturation or, in certain cases, fission product migration. Results are presented of experiments in which all the resolvable gamma peaks in the fission product spectrum have been used to calculate the fission rate; these results form a pattern which reflect errors in the literature values of the gamma branching ratios, fission yields etc., and also represent a series of empirical correction factors. Axial and diametral scanning experiments on a long-irradiated low-enrichment fuel element are also described and demonstrate that it is possible to differentiate between fissions in U-235 and in Pu-239 respectively by means of the ratios of the Ru-106 activity to the activities of the other fission products.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Chaobi; Chen, Jian Yun; Xu, Qiang; Li, Jing [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian (China)
2015-08-15
In order to analyze the mechanical properties of two-way different configurations of prestressed concrete members subjected to axial loading, a finite element model based on the nuclear power plant containments is demonstrated. This model takes into account the influences of different principal stress directions, the uniaxial or biaxial loading, and biaxial loading ratio. The displacement-controlled load is applied to obtain the stress-strain response. The simulated results indicate that the differences of principal stress axes have great effects on the stress-strain response under uniaxial loading. When the specimens are subjected to biaxial loading, the change trend of stress with the increase of loading ratio is obviously different along different layout directions. In addition, correlation experiments and finite element analyses were conducted to verify the validity and reliability of the analysis in this study.
Thermocapillary Convection in Floating Zone with Axial Magnetic Fields
Liang, Ruquan; Yang, Shuo; Li, Jizhao
2014-02-01
Numerical simulations on the effects of axial magnetic fields on the thermocapillary convection in a liquid bridge of silicone-oil-based ferrofluid under zero gravity have been conducted. The Navier-Stokes equations coupled with the energy conservation equation are solved on a staggered grid, and the mass conserving level set approach is used to capture the free surface deformation of the liquid bridge. The obvious effects of the magnetic fields on the flow pattern as well as the velocity and temperature distributions in the liquid bridge can be detected. The axial magnetic fields suppress the thermocapillary convection and a stagnant flow zone is formed between the circulating flow and the symmetric axis as the magnetic fields increase. The axial magnetic fields affect not only the velocity level inside the liquid bridge but also the velocity level on the free surface. The temperature contours near the free surface illustrates conduction-type temperature profiles at moderate strength fields.
Ball Screw Actuator Including an Axial Soft Stop
Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)
2016-01-01
An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.
Improvement of axial power distribution synthesis methodology in CPC
International Nuclear Information System (INIS)
Kim, H. H.; Gee, S. G.;; Kim, Y. B.; In, W. K.
2003-01-01
The capability of axial power distribution synthesis in CPC plays an important role in determining the DNBR and LPD trip caused by CPC. The axial power distribution is synthesized using the cubic spline function based on the three excore detector signals. The axial power distributions are categorized into 8 function sets and each sets are stored as pre-calculated values in CPC to save the calculation time. In this study, the additional function sets, the real break-point function sets and the polynomial function are suggested to evaluate the possibility of improving the synthesis capability in CPC. In addition, RMS errors are compared and evaluated for each synthesis method. As a result, it was confirmed that the function sets stored in CPC were not optimal. The analysis result showed that RMS error could be reduced by selecting the proper function sets suggested in this study
Axially modulated arch resonator for logic and memory applications
Hafiz, Md Abdullah Al
2018-01-17
We demonstrate reconfigurable logic and random access memory devices based on an axially modulated clamped-guided arch resonator. The device is electrostatically actuated and the motional signal is capacitively sensed, while the resonance frequency is modulated through an axial electrostatic force from the guided side of the microbeam. A multi-physics finite element model is used to verify the effectiveness of the axial modulation. We present two case studies: first, a reconfigurable two-input logic gate based on the linear resonance frequency modulation, and second, a memory element based on the hysteretic frequency response of the resonator working in the nonlinear regime. The energy consumptions of the device for both logic and memory operations are in the range of picojoules, promising for energy efficient alternative computing paradigm.
Program for beam optical computation of axial symmetrical electrostatic systems
International Nuclear Information System (INIS)
Ke Jianlin; Wu Chunlei; Zhou Changgeng
2012-01-01
The beam optical computation of axial symmetrical electrostatic systems is very important in the design and test of low-energy accelerators such as Cock-Croft and Van de Graaf accelerators. In this paper, a program for the beam optical computation of these structures has been developed using transfer matrix method. The electrostatic field region is divided into several small intervals in the program, and then the beam envelope is calculated interval-to-interval from the axial potential distribution, which is calculated by other electromagnetic field simulation software such as Maxwell SV. Space charge effect is included so that the program can be used in the computation of intense beam, while nonlinear effect is beyond its ability. The program can be used in the calculation of beam optics in most complicated axial symmetrical electrostatic fields, and the computing time required is very short. (authors)
Progressive atlanto-axial subluxation in Behcet's disease
International Nuclear Information System (INIS)
Kim, Sang-hyuk; Eoh, Whan
2010-01-01
Behcet's disease is a chronic inflammatory condition involving several organs, such as the skin, mucous membranes, eyes, joints, intestines, lungs and central nervous system. It rarely affects the spinal column. We describe a case of progressive atlanto-axial subluxation in a 44-year-old woman with Behcet's disease. The patient started complaining of posterior neck pain 10 years after the diagnosis of her Behcet's disease. Initial radiographs showed no abnormal finding, but follow-up radiographs 6 month later demonstrated atlanto-axial subluxation. To the best of our knowledge, this is the second reported case in the worldwide literature of an atlanto-axial instability in a patient with Behcet's disease. (orig.)
Bifurcation and chaos of an axially accelerating viscoelastic beam
International Nuclear Information System (INIS)
Yang Xiaodong; Chen Liqun
2005-01-01
This paper investigates bifurcation and chaos of an axially accelerating viscoelastic beam. The Kelvin-Voigt model is adopted to constitute the material of the beam. Lagrangian strain is used to account for the beam's geometric nonlinearity. The nonlinear partial-differential equation governing transverse motion of the beam is derived from the Newton second law. The Galerkin method is applied to truncate the governing equation into a set of ordinary differential equations. By use of the Poincare map, the dynamical behavior is identified based on the numerical solutions of the ordinary differential equations. The bifurcation diagrams are presented in the case that the mean axial speed, the amplitude of speed fluctuation and the dynamic viscoelasticity is respectively varied while other parameters are fixed. The Lyapunov exponent is calculated to identify chaos. From numerical simulations, it is indicated that the periodic, quasi-periodic and chaotic motions occur in the transverse vibrations of the axially accelerating viscoelastic beam
Reducing gait speed affects axial coordination of walking turns.
Forsell, Caroline; Conradsson, David; Paquette, Caroline; Franzén, Erika
2017-05-01
Turning is a common feature of daily life and dynamic coordination of the axial body segments is a cornerstone for safe and efficient turning. Although slow walking speed is a common trait of old age and neurological disorders, little is known about the effect of walking speed on axial coordination during walking turns. The aim of this study was to investigate the influence of walking speed on axial coordination during walking turns in healthy elderly adults. Seventeen healthy elderly adults randomly performed 180° left and right turns while walking in their self-selected comfortable pace and in a slow pace speed. Turning velocity, spatiotemporal gait parameters (step length and step time), angular rotations and angular velocity of the head and pelvis, head-pelvis separation (i.e. the angular difference in degrees between the rotation of the head and pelvis) and head-pelvis velocity were analyzed using Wilcoxon signed-rank tests. During slow walking, turning velocity was 15% lower accompanied by shorter step length and longer step time compared to comfortable walking. Reducing walking speed also led to a decrease in the amplitude and velocity of the axial rotation of the head and pelvis as well as a reduced head-pelvis separation and angular velocity. This study demonstrates that axial coordination during turning is speed dependent as evidenced by a more 'en bloc' movement pattern (i.e. less separation between axial segments) at reduced speeds in healthy older adults. This emphasizes the need for matching speed when comparing groups with diverse walking speeds to differentiate changes due to speed from changes due to disease. Copyright © 2017 Elsevier B.V. All rights reserved.
[Myopia: frequency of lattice degeneration and axial length].
Martín Sánchez, M D; Roldán Pallarés, M
2001-05-01
To evaluate the relationship between lattice retinal degeneration and axial length of the eye in different grades of myopia. A sample of 200 eyes from 124 myopic patients was collected by chance. The average age was 34.8 years (20-50 years) and the myopia was between 0.5 and 20 diopters (D). The eyes were grouped according to the degree of refraction defect, the mean axial length of each group (Scan A) and the frequency of lattice retinal degeneration and the relationship between these variables was studied. The possible influence of age on our results was also considered. For the statistical analysis, the SAS 6.07 program with the variance analysis for quantitative variables, and chi(2) test for qualitative variables with a 5% significance were used. A multivariable linear regression model was also adjusted. The highest frequency of lattice retinal degeneration occurred in those myopia patients having more than 15 D, and also in the group of myopia patients between 3 and 6 D, but this did not show statistical significance when compared with the other myopic groups. If the axial length is assessed, a greater frequency of lattice retinal degeneration is also found when the axial length is 25-27 mm and 29-30 mm, which correspond, respectively, to myopias between 3-10 D and more than 15 D. When the multivariable linear regression model was adjusted, the axial length showed the existence of lattice retinal degeneration (beta 0.41 mm; p=0.08) adjusted by the number of diopters (beta 0.38 mm; plattice retinal degeneration was found for myopias with axial eye length between 29-30 mm (more than 15 D), and 25-27 mm (between 3-10 D).
Prediction of secular acceleration of axial rotation of Mars
Barkin, Yu. V.
2009-04-01
axial rotation which as it would be possible to expect, essentially surpasses the similar characteristic of rotation of the Earth. The obtained result means, that angular velocity of Mars in present period increases on the law r = (0.708821808000+ 0.000000001038×t) × 10-4 1/s, here t - in years. It is possible assume that the estimation of acceleration can be obtained directly on the basis of the data of observations in the nearest years. Velocity of secular change of duration of day for Mars (LOD) thus can make significant value about -0.0903 ms/yr, that considerably surpasses similar value for non-tidal acceleration of the Earth (-0.006 ms/yr). The ratio of positive acceleration of the Earth rotation á¹ to its angular velocity ? makes á¹? = (6.9± 1.7) × 10-11 1/yr[7]. In case of Mars the estimation of acceleration was carried out under the formula [8]: á¹/ ? = -Ä C -á¹ ° G ?-Ä C = 103.8 × 10-11 1/yr. We here have neglected by an influence of secular change of the axial angular momentum of fluid masses (atmospheric and underground) of Marsá¹ °. As shown in other my report on EGU GA 2009 in case of the Earth the total angular momentum of fluids really is small and within the limits of mistakes can be accepted equal to zero. In the case of Mars we the same as and in case of the Earth, expect of secular change of the angular momentum of Mars and change of global superrotation of its atmosphere which, at least, in part, will be compensated by the angular momentum of fluids. Thus, expected non-tidal acceleration of axial rotation of Mars can be at 10-15 times more those, but observably by astronomical methods, for the Earth. Certainly, the estimations obtained here are preliminary and the phenomena discussed here require more detailed studying with using of new data of precision observations. First of all it is important to obtain the specified values of secular variations Ë J2 and Ë J3. In case of the Earth the tidal deceleration
Axial Permanent Magnet Generator for Wearable Energy Harvesting
DEFF Research Database (Denmark)
Högberg, Stig; Sødahl, Jakob Wagner; Mijatovic, Nenad
2016-01-01
An increasing demand for battery-free electronics is evident by the rapid increase of wearable devices, and the design of wearable energy harvesters follows accordingly. An axial permanent magnet generator was designed to harvest energy from human body motion and supplying it to a wearable...... application. The design was approached from an lectromagnetic point of view in this article. Two types of axial flux permanent magnet generators were designed: one with an iron yoke, which is commonly used to reduce the machine volume and demand of permanent magnets, and a second without the iron yoke...
Manufacture of axially insulated large-area diodes
International Nuclear Information System (INIS)
Ma Weiyi; Zhou Kungang; Wang Youtian; Zhang Dong; Shan Yusheng; Wang Naiyan
1999-01-01
The author describes the design and construction of the axially insulated large-area diodes used in the 'Heaven-1'. The four axially insulated large-area diodes are connected to the 10 ohm pulse transmission lines via the vacuum feed through tubes. The experimental results with the diodes are given. The diodes can steadily work at the voltage of 650 kV, and the diode current density is about 80 A per cm 2 with a pulse width of 220 ns. The electron beams with a total energy of 25 kJ are obtained
Periodicity effects of axial waves in elastic compound rods
DEFF Research Database (Denmark)
Nielsen, R. B.; Sorokin, S. V.
2015-01-01
Floquet analysis is applied to the Bernoulli-Euler model for axial waves in a periodic rod. Explicit asymptotic formulae for the stop band borders are given and the topology of the stop band pattern is explained. Eigenfrequencies of the symmetric unit cell are determined by the Phase-closure Prin......Floquet analysis is applied to the Bernoulli-Euler model for axial waves in a periodic rod. Explicit asymptotic formulae for the stop band borders are given and the topology of the stop band pattern is explained. Eigenfrequencies of the symmetric unit cell are determined by the Phase...
Buckling localization in a cylindrical panel under axial compression
DEFF Research Database (Denmark)
Tvergaard, Viggo; Needleman, A.
2000-01-01
Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile...... test specimens is discussed in general. For the cylindrical panel, it is shown that buckling localization develops shortly after a maximum load has been attained, and this occurs for a purely elastic panel as well as for elastic-plastic panels. In a case where localization occurs after a load maximum...
Spectral analysis in thin tubes with axial heterogeneities
Ferreira, Rita
2015-01-01
In this paper, we present the 3D-1D asymptotic analysis of the Dirichlet spectral problem associated with an elliptic operator with axial periodic heterogeneities. We extend to the 3D-1D case previous 3D-2D results (see [10]) and we analyze the special case where the scale of thickness is much smaller than the scale of the heterogeneities and the planar coefficient has a unique global minimum in the periodic cell. These results are of great relevance in the comprehension of the wave propagation in nanowires showing axial heterogeneities (see [17]).
A simple approach to the ABJ axial anomaly
International Nuclear Information System (INIS)
Horejsi, J.
1985-01-01
A very simple semi-quantitative derivation of the Adler-Bell-Jackiw (ABJ) axial anomaly is given, based on an investigation of the absorptive part of the VVA triangle graph and dispersion relations. Essential ingredients of our discussion are: normal Ward identities for the absorptive part of the relevant diagram, dimensional analysis, unitarity, and energy-momentum conservation. An explanation of the physical origin of axial anomaly, proposed in some earlier treatments within such a dispersive framework, is critically examined. In particular, the interpretation of the ABJ anomaly as an analogy of the Lee-Nauenberg effect occurring in the massless limit of spinor electrodynamics is shown to be fallacious
Light-front view of the axial anomaly
International Nuclear Information System (INIS)
Ji, C.; Rey, S.
1996-01-01
Motivated by an apparent puzzle of the light-front vacua incompatible with the axial anomaly, we have considered the two-dimensional massless Schwinger model for an arbitrary interpolating angle of Hornbostel close-quote s interpolating quantization surface. By examining spectral deformation of the Dirac sea under an external electric field semiclassically, we have found that the axial anomaly is quantization angle independent. This indicates an intricate nontrivial vacuum structure present even in the light-front limit. copyright 1996 The American Physical Society
Study on Predicting Axial Load Capacity of CFST Columns
Ravi Kumar, H.; Muthu, K. U.; Kumar, N. S.
2017-11-01
This work presents an analytical study and experimental study on the behaviour and ultimate load carrying capacity of axially compressed self-compacting concrete-filled steel tubular columns. Results of tests conducted by various researchers on 213 samples concrete-filled steel tubular columns are reported and present authors experimental data are reported. Two theoretical equations were derived for the prediction of the ultimate axial load strength of concrete-filled steel tubular columns. The results from prediction were compared with the experimental data. Validation to the experimental results was made.
Computed tomographic myelography (CTM) in atlanto-axial rheumatoid arthritis
International Nuclear Information System (INIS)
Laasonen, E.M.; Servo, A.; Kankaanpaeae, U.; Paukku, P.; Sandelin, J.; Slaetis, P.
1985-01-01
Thirty-two patients with severe cervical rheumatoid arthritis were investigated preoperatively with cervical myelography (CeM) and computed tomographic myelography (CTM). The severity of their clinical symptoms correlated excellently with a combination of the deformation of the spinal cord at the atlanto-axial level, the lateral dislocation of the cord at the same level, and the deformation of the cord at some lower cervical level. Obstructing softtissue excrescences seemed to have little value. No correlation was found in this study between the deformation of the cord and the main findings of the plain films: the atlanto-axial subluxation (AAS), the vertical subluxation (VS), or their combination. (orig.)
DEFF Research Database (Denmark)
Kjærgaard, Søren; Canudas-Romo, Vladimir
2017-01-01
, the prospective potential support ratio usually focuses on the current mortality schedule, or period life expectancy. Instead, in this paper we look at the actual mortality experienced by cohorts in a population, using cohort life tables. We analyse differences between the two perspectives using mortality models......, historical data, and forecasted data. Cohort life expectancy takes future mortality improvements into account, unlike period life expectancy, leading to a higher prospective potential support ratio. Our results indicate that using cohort instead of period life expectancy returns around 0.5 extra younger...
Montalvão, Diogo; Wren, Andrew
2017-11-01
The necessity to increase performances in terms of lifetime and security in mechanical components or structures is the motivation for intense research in fatigue. Applications range from aeronautics to medical devices. With the development of new materials, there is no longer a fatigue limit in the classical sense, where it was accepted that the fatigue limit is the stress level such that there is no fracture up to 1E7 cycles. The recent development of ultrasonic testing machines where frequencies can go as high as 20 kHz or over enabled tests to be extended to ranges larger than 1E9 in just a few days. This area of studies is now known as Very High Cycle Fatigue (VHCF). On the other hand, most of the existing test equipment in the market for both classical and VHCF are uniaxial test machines. However, critical components used in Engineering applications are usually subjected to complex multi-axial loading conditions. In this paper, it is presented the methodology to redesigning existing cruciform test specimens that can be used to create an in-plane biaxial state of stress when used in 'uniaxial' VHCF ultrasonic testing machines (in this case, the term 'uniaxial' is used not because of the state of stress created at the centre of the specimen, but because of the direction at which the load is applied). The methodology is explained in such a way that it can be expanded to other existing designs, namely cruciform designs, that are not yet used in VHCF. Also, although the approach is presented in simple and logical terms, it may not be that obvious for those who have a more focused approach on fatigue rather than on modal analysis. It is expected that by contributing to bridging the gap between the sciences of modal analysis and fatigue, this research will help and encourage others exploiting new capabilities in VHCF.
Directory of Open Access Journals (Sweden)
PO de Wet
2005-06-01
Full Text Available The rectilinear Steiner ratio was shown to be 3/2 by Hwang [Hwang FK, 1976, On Steiner minimal trees with rectilinear distance, SIAM Journal on Applied Mathematics, 30, pp. 104– 114.]. We use continuity and introduce restricted point sets to obtain an alternative, short and self-contained proof of this result.
DEFF Research Database (Denmark)
Nicolaisen, Jeppe; Faber Frandsen, Tove
2008-01-01
The paper introduces a new journal impact measure called The Reference Return Ratio (3R). Unlike the traditional Journal Impact Factor (JIF), which is based on calculations of publications and citations, the new measure is based on calculations of bibliographic investments (references) and returns...
Supersymmetric axial anomalies and the Wess-Zumino action
International Nuclear Information System (INIS)
Harada, K.; Shizuya, K.
1988-01-01
We derive, by an algebraic method, a manifestly supersymmetric extension of Bardeen's minimal form of axial anomalies, which obeys the Wess-Zumino consistency condition. The left-right symmetric form of the anomalies is also obtained by a reduction procedure. We construct the supersymmetric Wess-Zumino effective action and study its low-energy features. (orig.)
Dynamic Response of Axially Loaded Euler-Bernoulli Beams
DEFF Research Database (Denmark)
Bayat, M.; Barari, Amin; Shahidi, M.
2011-01-01
The current research deals with application of a new analytical technique called Energy Balance Method (EBM) for a nonlinear problem. Energy Balance Method is used to obtain the analytical solution for nonlinear vibration behavior of Euler-Bernoulli beams subjected to axial loads. Analytical...
Axial Torsion of Gangrenous Meckel's Diverticulum Causing Small ...
African Journals Online (AJOL)
dividing the band. Resection and anastomosis of the small bowel including the MD was performed. We hereby report a rare and unusual complication of a MD. Although treatment outcome is generally good, pre-operative diagnosis is often difficult. Key words: Axial torsion, Meckel's diverticulum, small bowel obstruction.
A cylindrical drift chamber with azimuthal and axial position readout
Energy Technology Data Exchange (ETDEWEB)
Bar-Yam, Z.; Cummings, J.P.; Dowd, J.P.; Eugenio, P.; Hayek, M.; Kern, W.; King, E.; Shenhav, N.; Chung, S.U.; Hackenburg, R.W.; Olchanski, C.; Weygand, D.P.; Willutzki, H.J.; Brabson, B.B.; Crittenden, R.R.; Dzierba, A.R.; Gunter, J.; Lindenbusch, R.; Rust, D.R.; Scott, E.; Smith, P.T.; Sulanke, T.; Teige, S.; Denisov, S.; Dushkin, A.; Kochetkov, V.; Lipaev, V.; Popov, A.; Shein, I.; Soldatov, A.; Anoshina, E.V.; Bodyagin, V.A.; Demianov, A.I.; Gribushin, A.M.; Kodolova, O.L.; Korotkikh, V.L.; Kostin, M.A.; Ostrovidov, A.I.; Sarycheva, L.I.; Sinev, N.B.; Vardanyan, I.N.; Yershov, A.A.; Adams, T.; Bishop, J.M.; Cason, N.M.; Sanjari, A.H.; LoSecco, J.M.; Manak, J.J.; Shephard, W.D.; Stienike, D.L.; Taegar, S.A.; Thompson, D.R.; Brown, D.S.; Pedlar, T.; Seth, K.K.; Wise, J.; Zhao, D.; Adams, G.S.; Napolitano, J.; Nozar, M.; Smith, J.A.; Witkowski, M. [Massachusetts Univ., North Dartmouth, MA (United States)]|[Brookhaven National Laboratory, Upton, L.I., NY 11973 (United States)]|[Indiana University, Bloomington, IN 47405 (United States)]|[Institute for High Energy Physics, Protvino (Russian Federation)]|[Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation)]|[University of Notre Dame, Notre Dame, IN 46556 (United States)]|[Northwestern University, Evanston, IL 60208 (United States)]|[Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)
1997-02-21
A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in {pi}{sup -}p interactions. We describe the chamber`s design considerations, details of its construction, electronics, and performance characteristics. (orig.).
Studi Regangan Axial dan Lateral pada Tanah Ekspansif
Directory of Open Access Journals (Sweden)
Lisa Fitriyana
2017-07-01
Full Text Available Swelling and shrinkage abilities of soils are dangerous for buildings. According to Hardiyatmo (2014 There are two types of swelling in expansive soils that are the movement of lateral (horizontal and axial (vertical. Oftentimes the deformation of soils cannot be supported by building stiffness. This damage can be seen in retaining walls, tunnel walls, and etc. With the aims to identify an expansive soil and to know its lateral and axial strains, an experimental study was performed. Swelling tests were conducted in a specimen having diameter (d of 4,5 cm and height (h0 of 2 cm with the variations in : 1 water content wopt = 31% and 18%; 2 vertical pressure (pv 1 kPa, 3.5 kPa and 6.9 kPa; and 3 membrane thickness (t 0.7 mm and 0.5 mm. The strain in the axial direction was measured with a dial gauge that was set vertically parallel whereas the lateral strain is by measuring changes in diameter of the specimen with a digital caliper measurement tools. Based on the analysis on the identification results, the observed soil is classified as expansive soil with the expansion potential is high average. The test results show the same potential for the occurrence of lateral and lateral strain if the lateral retention (e.g. retaining wall is weak. The largest lateral and axial soil development occurred at water content w0 = 18% are 15.7% and 15.8% respectively.
Axial-Gap Induction Motor For Levitated Specimens
Sridharan, Govind; Rhim, Won-Kyu; Barber, Dan; Chung, Sang
1992-01-01
Motor does not obscure view of specimen. Axial-gap induction motor applies torque to rotate electrostatically or electromagnetically levitated specimen of metal. Possible applications include turning specimens for uniform heating under focused laser beams and obtaining indirect measurements of resistivities or of surface tensions in molten specimens.
On aspects of vibration of axially moving continua
Hageraats-Ponomareva, S.
2009-01-01
In axially moving structures like conveyor belt systems, magnetic tapes, and so on, vibrations occur due to the presence of different kinds of imperfections in the systems. For these structures internal resonances can lead to severe vibrations. Resonance free conveyor belt systems can be constructed
Solution of the gauge identities in the axial gauge
International Nuclear Information System (INIS)
Delbourgo, R.
1981-01-01
Starting from the spectral representation of the two-point functions in the axial gauge, the gauge identities are solved so as to express the higher-point Green functions linearly in terms of the two-point spectral function. The four-point functions are an important input for investigations of scalar electrodynamics and vector chromodynamics based on the gauge technique. (author)
3-D Simulation of Vertical-Axial Tidal Current Turbine
Directory of Open Access Journals (Sweden)
Zhiyang Zhang
2016-12-01
Full Text Available Vertical-axial tidal current turbine is the key for the energy converter, which has the advantages of simple structure, adaptability to flow and uncomplex convection device. It has become the hot point for research and application recently. At present, the study on the hydrodynamic performance of vertical-axial tidal current turbine is almost on 2-D numerical simulation, without the consideration of 3-D effect. CFD (Computational Fluid Dynamics method and blade optimal control technique are used to improve accuracy in the prediction of tidal current turbine hydrodynamic performance. Numerical simulation of vertical-axial tidal current turbine is validated. Fixed and variable deflection angle turbine are comparatively studied to analysis the influence of 3-D effect and the character of fluid field and pressure field. The method, put the plate on the end of blade, of reduce the energy loss caused by 3-D effect is proposed. The 3-D CFD numerical model of vertical-axial tidal current turbine hydrodynamic performance in this study may provide theoretical, methodical and technical reference for the optimal design of turbine.
View of the Axial Field Spectrometer (R807)
1980-01-01
In this view of the Axial Field Spectrometer at I8, the vertical uranium/scintillator hadron calorimeter (just left of centre) is retracted to give access to the cylindrical central drift chamber. The yellow iron structure served as a filter to identify muons, with MWPCs and the array of Cherenkov counters to the right.
Landforms along transverse faults parallel to axial zone of folded ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Earth System Science; Volume 126; Issue 1. Landforms along transverse faults parallel to axial zone of folded mountain front, north-eastern Kumaun Sub-Himalaya, India. Khayingshing ... Keywords. Himalayan Frontal Thrust; outer Kumaun Himalaya; transverse structure; folded mountain front.
sizing of wind powered axial flux permanent magnet alternator using
African Journals Online (AJOL)
user
2016-10-04
Oct 4, 2016 ... Using analytical calculations, the design parameters of the alternator's main dimensions were obtained in a ... SIZING OF WIND POWERED AXIAL FLUX PERMANENT MAGNET ALTERNATOR USING ANALYTICAL APPROACH,. A. O. Otuoze, et al .... then be expressed as. Equation (7) can be re-written as.
Evaluation of electromagnetic shielding effectiveness of multi-axial ...
Indian Academy of Sciences (India)
Abstract. The usage of electrical and electronic equipments has been increasing in daily life, which has a potential hazardous impact on humans and other living organisms. In this paper, multi-axial fabrics containing steel yarns and carbon filaments, and their polyester (PES) resin-reinforced composites have been ...
Ocular Axial Length and Keratometry Readings of Normal Eyes in ...
African Journals Online (AJOL)
Aim: To provide average axial length and keratometry readings in healthy eyes of people in Rivers and surrounding states in southern Nigeria. This may guide the purchase of intraocular lens in the study area. Materials and methods: Four hundred consecutive patients with 800 non-cataractous eyes attending the eye clinic ...
Axial drive to nonlinear flow between rotating cylinders
Ashrafi, Nariman; Hazbavi, Abbas
2014-02-01
Stability of pseudoplastic rotational flow between cylinders in presence of an independent axial component is investigated. The fluid is assumed to follow the Carreau model and mixed boundary conditions are imposed. The conservation of mass and momentum equations give rise to a four-dimensional low-order dynamical system, including additional nonlinear terms in the velocity components originated from the shear-dependent viscosity. In absence of the axial flow, as the pseudoplasticity effects increases, the purely-azimuthal base flow loses its stability to the vortex structure at a lower critical Taylor number. Emergence of the vortices corresponds to the onset of a supercritical bifurcation also present in the flow of a linear fluid. However, unlike the Newtonian case, pseudoplastic Taylor vortices lose their stability as the Taylor number reaches a second critical number corresponding to the onset of a Hopf bifurcation. Existence of an axial flow induced by a pressure gradient appears to further advance each critical point on the bifurcation diagram. In continuation, complete flow field together with viscosity maps is analyzed for different flow scenarios. Through evaluation of the Lyapunov exponent, flow stability and temporal behavior of the system for cases with and without axial flow are brought to attention.
Employing a tri-axial accelerometer for estimating energy ...
African Journals Online (AJOL)
The Tritrac-R3D, a portable tri-axial accelerometer, was assessed for its ability to estimate energy expenditure during simulated load carrying activities. The Tritrac data were compared to metabolic data collected simultaneously by a MetaMax ergospirometry system while ten, healthy male subjects (aged 20.7 ±1.4 years) ...
Numerical simulation of breakup and detachment of an axially ...
Indian Academy of Sciences (India)
Kishore Singh Patel
Abstract. The extensional, breakup and detachment dynamics of an axially stretching Newtonian liquid bridge are investigated numerically with a dynamic domain multiphase incompressible flow solver. The mul- tiphase flow solver employs a Cahn–Hilliard phase field model to describe the evolution of the diffuse interface.
Computation of the lateral and axial point spread functions in ...
Indian Academy of Sciences (India)
... confocal scanning microscopes for the above-mentioned amplitude filters. These results of axial and lateral irradiances are graphically represented by constructing a computer program using MATLAB. The obtained results are compared with that obtained in case of circular, annular, and Martinez-Corral apodized aperture ...
Axial heterogeneous core concept applied for super phoenix reactor
International Nuclear Information System (INIS)
Batista, J.L.; Renke, C.A.C.; Waintraub, M.; Santos Bastos, W. dos; Brito Aghina, L.O. de.
1991-11-01
Always maintaining the current design rules, this paper presents a parametric study on the type of axial heterogeneous core concept (CHA), utilizing a core of fast reactor Super Phenix type, reaching a maximum thermal burnup rate of 150000 M W d/t and being managed in single batch. (author)
Fission gas retention and axial expansion of irradiated metallic fuel
International Nuclear Information System (INIS)
Fenske, G.R.; Emerson, J.E.; Savoie, F.E.; Johanson, E.W.
1986-05-01
Out-of-reactor experiments utilizing direct electrical heating and infrared heating techniques were performed on irradiated metallic fuel. The results indicate accelerated expansion can occur during thermal transients and that the accelerated expansion is driven by retained fission gases. The results also demonstrate gas retention and, hence, expansion behavior is a function of axial position within the pin
Evaluation of electromagnetic shielding effectiveness of multi-axial ...
Indian Academy of Sciences (India)
2016-08-26
Aug 26, 2016 ... ... Lecture Workshops · Refresher Courses · Symposia. Home; Journals; Bulletin of Materials Science; Volume 39; Issue 4. Evaluation of electromagnetic shielding effectiveness of multi-axial fabrics and their reinforced PES composites. RAMAZAN ERDEM. Volume 39 Issue 4 August 2016 pp 963-970 ...
Evaluation of electromagnetic shielding effectiveness of multi-axial ...
Indian Academy of Sciences (India)
The usage of electrical and electronic equipments has been increasing in daily life, which has a potential hazardous impact on humans and other living organisms. In this paper, multi-axial fabrics containing steel yarns and carbon filaments, and their polyester (PES) resin-reinforced composites have been prepared for ...
first principles derivation of a stress function for axially symmetric
African Journals Online (AJOL)
HOD
found to be identical with the Love stress function. The stress function was then applied to solve the axially symmetric problem of finding the stress fields, strain fields and displacement fields in the semi-infinite linear elastic, isotropic homogeneous medium subject to a point load P acting at the origin of coordinates also ...
Kinetics and equilibria for the axial ligation of bromomethyl (aqua ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Chemical Sciences; Volume 121; Issue 6. Kinetics and equilibria for the axial ligation of bromomethyl (aqua)cobaloxime with pyridines - Isolation characterization and DNA binding. Kotha Laxma Reddy K Ashwini Kumar N Ravi Kumar Reddy Penumaka Nagababu A Panasa Reddy S ...
Axial anomaly and magnetism of nuclear and quark matter
Son, D. T.; Stephanov, M. A.
2008-01-01
We consider the response of the QCD ground state at finite baryon density to a strong magnetic field B. We point out the dominant role played by the coupling of neutral Goldstone bosons, such as π0, to the magnetic field via the axial triangle anomaly. We show that, in vacuum, above a value of B˜mπ2/e, a metastable object appears—the π0 domain wall. Because of the axial anomaly, the wall carries a baryon number surface density proportional to B. As a result, for B≳1019G a stack of parallel π0 domain walls is energetically more favorable than nuclear matter at the same density. Similarly, at higher densities, somewhat weaker magnetic fields of order B≳1017 1018G transform the color-superconducting ground state of QCD into new phases containing stacks of axial isoscalar (η or η') domain walls. We also show that a quark-matter state known as “Goldstone current state,” in which a gradient of a Goldstone field is spontaneously generated, is ferromagnetic due to the axial anomaly. We estimate the size of the fields created by such a state in a typical neutron star to be of order 1014 1015G.
Modelling the cardiac transverse-axial tubular system
Czech Academy of Sciences Publication Activity Database
Pásek, Michal; Šimurda, J.; Christé, G.; Orchard, C.
2008-01-01
Roč. 96, - (2008), s. 226-246 ISSN 0079-6107 Institutional research plan: CEZ:AV0Z20760514 Keywords : cardiac cell * transverse-axial tubular system * quantitative modelling Subject RIV: BO - Biophysics Impact factor: 6.388, year: 2008
Comparison of design methods for axially loaded buckets in sand
DEFF Research Database (Denmark)
Vaitkunaite, Evelina; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo
2015-01-01
A study of the present knowledge about the bucket resistance for axial loading was performed considering analytical and numerical design methods as well as physical models. A case study was performed with two bucket foundations of equal diameter, but different skirt lengths installed in dense san...
Axial and focal-plane diffraction catastrophe integrals
International Nuclear Information System (INIS)
Berry, M V; Howls, C J
2010-01-01
Exact expressions in terms of Bessel functions are found for some of the diffraction catastrophe integrals that decorate caustics in optics and mechanics. These are the axial and focal-plane sections of the elliptic and hyperbolic umbilic diffraction catastrophes, and symmetric elliptic and hyperbolic unfoldings of the X 9 diffraction catastrophes. These representations reveal unexpected relations between the integrals.
Atlanto-axial instability in rheumatoid arthritis: a review | Omar ...
African Journals Online (AJOL)
Objectives: The purpose of this literature review is to identify common lesions present in the rheumatoid neck with specific emphasis to atlanto-axial instability, review its clinical presentation, imaging findings and management. Study design: A review of the English medical literature was done with focus on recent studies ...
Ocular Axial Length Measurement Among Normal Adults Using ...
African Journals Online (AJOL)
2017-07-26
Jul 26, 2017 ... Background/Introduction: Macrophthalmia and microphthalmia are cardinal signs of many orbito-ocular and systemic diseases which are seen in northern Nigeria. Some cases of refractive error may also be directly related to the ocular axial length (AL). The need for an imaging parameter that will aid their ...
Axial Torsion of Gangrenous Meckel's Diverticulum Causing Small ...
African Journals Online (AJOL)
Meckel's diverticulum (MD) is a commonly encountered congenital anomaly of the small intestine. We report an extremely unusual case of an axially torted, gangrenous MD presenting as acute intestinal obstruction. A 26-year-old male patient presented to our emergency department with 3 days history of abdominal pain, ...
Computation of the lateral and axial point spread functions in ...
Indian Academy of Sciences (India)
scanning microscopes for the above-mentioned amplitude filters. These results of axial and lateral irradiances are graphically represented by constructing a computer program using MATLAB. The obtained results are compared with that obtained in case of circular, annular, and Martinez-Corral apodized aperture. Keywords ...
Fatigue Limit of Axially Compressed Concrete | Levchich | Nigerian ...
African Journals Online (AJOL)
An attempt to evaluate analytically the fatigue limit of axially loaded concrete depending upon the load parameters, number of load cycles and static short-term strength is presented. The conventional limit of concrete microcracking statical sustained strength of concrete, curvelinear relationship between fatigue limit and load ...
Severe vertical atlanto-axial subluxation in rheumatoid arthritis
Directory of Open Access Journals (Sweden)
Sílvia Fernandes
2015-01-01
Full Text Available The authors present the imaging study of a case of severe vertical atlanto-axial subluxation in a 60-year-old male with long-term rheumatoid arthritis with severe polyarticular involvement (Class IV of Steinbrocker functional classification.
Report on the Dynamical Evolution of an Axially Symmetric Quasar ...
Indian Academy of Sciences (India)
2016-01-27
Jan 27, 2016 ... The role of the angular momentum in the regular or chaotic character of motion in an axially symmetric quasar model is examined. It is found that, for a given value of the critical angular momentum , there are two values of the mass of the nucleus for which transition from regular to chaotic motion ...
Report on the Dynamical Evolution of an Axially Symmetric Quasar ...
Indian Academy of Sciences (India)
Abstract. The role of the angular momentum in the regular or chaotic character of motion in an axially symmetric quasar model is examined. It is found that, for a given value of the critical angular momentum Lzc, there are two values of the mass of the nucleus Mn for which transition from regular to chaotic motion occurs.
Axial-flow fan with eccentric rotor | Blaho | Zede Journal
African Journals Online (AJOL)
Axial-flow fan with eccentric rotor. M Blaho. Abstract. No Abstract. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER RESOURCES... for Researchers · for Journals ...
Energy Technology Data Exchange (ETDEWEB)
None
1979-02-28
Progress in developing and testing a continuously variable ratio hydraulic transmission unit for automobiles is reported. Major emphasis was placed on the development of a co-axial hydrostatic module.
The Nucleon Axial Form Factor and Staggered Lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Meyer, Aaron Scott [Chicago U.
2017-01-01
The study of neutrino oscillation physics is a major research goal of the worldwide particle physics program over the upcoming decade. Many new experiments are being built to study the properties of neutrinos and to answer questions about the phenomenon of neutrino oscillation. These experiments need precise theoretical cross sections in order to access fundamental neutrino properties. Neutrino oscillation experiments often use large atomic nuclei as scattering targets, which are challenging for theorists to model. Nuclear models rely on free-nucleon amplitudes as inputs. These amplitudes are constrained by scattering experiments with large nuclear targets that rely on the very same nuclear models. The work in this dissertation is the rst step of a new initiative to isolate and compute elementary amplitudes with theoretical calculations to support the neutrino oscillation experimental program. Here, the eort focuses on computing the axial form factor, which is the largest contributor of systematic error in the primary signal measurement process for neutrino oscillation studies, quasielastic scattering. Two approaches are taken. First, neutrino scattering data on a deuterium target are reanalyzed with a model-independent parametrization of the axial form factor to quantify the present uncertainty in the free-nucleon amplitudes. The uncertainties on the free-nucleon cross section are found to be underestimated by about an order of magnitude compared to the ubiquitous dipole model parametrization. The second approach uses lattice QCD to perform a rst-principles computation of the nucleon axial form factor. The Highly Improved Staggered Quark (HISQ) action is employed for both valence and sea quarks. The results presented in this dissertation are computed at physical pion mass for one lattice spacing. This work presents a computation of the axial form factor at zero momentum transfer, and forms the basis for a computation of the axial form factor momentum dependence
Axial SPN and radial MOC coupled whole core transport calculation
International Nuclear Information System (INIS)
Cho, Jin-Young; Kim, Kang-Seog; Lee, Chung-Chan; Zee, Sung-Quun; Joo, Han-Gyu
2007-01-01
The Simplified P N (SP N ) method is applied to the axial solution of the two-dimensional (2-D) method of characteristics (MOC) solution based whole core transport calculation. A sub-plane scheme and the nodal expansion method (NEM) are employed for the solution of the one-dimensional (1-D) SP N equations involving a radial transverse leakage. The SP N solver replaces the axial diffusion solver of the DeCART direct whole core transport code to provide more accurate, transport theory based axial solutions. In the sub-plane scheme, the radial equivalent homogenization parameters generated by the local MOC for a thick plane are assigned to the multiple finer planes in the subsequent global three-dimensional (3-D) coarse mesh finite difference (CMFD) calculation in which the NEM is employed for the axial solution. The sub-plane scheme induces a much less nodal error while having little impact on the axial leakage representation of the radial MOC calculation. The performance of the sub-plane scheme and SP N nodal transport solver is examined by solving a set of demonstrative problems and the C5G7MOX 3-D extension benchmark problems. It is shown in the demonstrative problems that the nodal error reaching upto 1,400 pcm in a rodded case is reduced to 10 pcm by introducing 10 sub-planes per MOC plane and the transport error is reduced from about 150 pcm to 10 pcm by using SP 3 . Also it is observed, in the C5G7MOX rodded configuration B problem, that the eigenvalues and pin power errors of 180 pcm and 2.2% of the 10 sub-planes diffusion case are reduced to 40 pcm and 1.4%, respectively, for SP 3 with only about a 15% increase in the computing time. It is shown that the SP 5 case gives very similar results to the SP 3 case. (author)
Grimbach, A; Knechtli, F; Palombi, Filippo
2008-01-01
We calculate analytically the improvement coefficients of the static axial and vector currents in O(a) improved lattice QCD at one-loop order of perturbation theory. The static quark is described by the hypercubic action, previously introduced in the literature in order to improve the signal-to-noise ratio of static observables. Within a Schroedinger Functional setup, we derive the Feynman rules of the hypercubic link in time-momentum representation. The improvement coefficients are obtained from on-shell correlators of the static axial and vector currents. As a by-product, we localise the minimum of the static self-energy as a function of the smearing parameters of the action at one-loop order and show that the perturbative minimum is close to its non-perturbative counterpart.
Kroon, Feline P. B.; van der Burg, Lennart R. A.; Ramiro, Sofia; Landewé, Robert B. M.; Buchbinder, Rachelle; Falzon, Louise; van der Heijde, Désirée
2015-01-01
Axial spondyloarthritis (axSpA) comprises ankylosing spondylitis (radiographic axSpA) and non-radiographic (nr-)axSpA and is associated with psoriasis, uveitis and inflammatory bowel disease. Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as first-line drug treatment. To determine
International Nuclear Information System (INIS)
Ghayesh, Mergen H.; Amabili, Marco; Farokhi, Hamed
2013-01-01
In the present study, the coupled nonlinear dynamics of an axially moving viscoelastic beam with time-dependent axial speed is investigated employing a numerical technique. The equations of motion for both the transverse and longitudinal motions are obtained using Newton’s second law of motion and the constitutive relations. A two-parameter rheological model of the Kelvin–Voigt energy dissipation mechanism is employed in the modelling of the viscoelastic beam material, in which the material time derivative is used in the viscoelastic constitutive relation. The Galerkin method is then applied to the coupled nonlinear equations, which are in the form of partial differential equations, resulting in a set of nonlinear ordinary differential equations (ODEs) with time-dependent coefficients due to the axial acceleration. A change of variables is then introduced to this set of ODEs to transform them into a set of first-order ordinary differential equations. A variable step-size modified Rosenbrock method is used to conduct direct time integration upon this new set of first-order nonlinear ODEs. The mean axial speed and the amplitude of the speed variations, which are taken as bifurcation parameters, are varied, resulting in the bifurcation diagrams of Poincaré maps of the system. The dynamical characteristics of the system are examined more precisely via plotting time histories, phase-plane portraits, Poincaré sections, and fast Fourier transforms (FFTs)
Axial compression behaviour of reinforced wallettes fabricated using wood-wool cement panel
Noh, M. S. Md; Kamarudin, A. F.; Mokhatar, S. N.; Jaudin, A. R.; Ahmad, Z.; Ibrahim, A.; Muhamad, A. A.
2018-04-01
Wood-wool cement composite panel (WWCP) is one of wood based composite material that produced in a stable panel form and suitable to be used as building wall system to replace non-ecofriendly material such as brick and other masonry element. Heavy construction material such as brick requires more manpower and consume a lot of time to build the wall panel. WWCP is a lightweight material with a density range from 300 kg/m3 to 500 kg/m3 and also capable to support an imposed load from the building. This study reported on the axial compression behaviour of prefabricated reinforced wallettes constructed with wood-wool cement panel. A total of six specimens were fabricated using two layers of cross laminated WWCP bonded with normal mortar paste (Portland cement) at a mix ratio of 1:3 (cement : sand). As part of lifting mechanism, the wallettes were equipped with three steel reinforcement (T12) that embedded inside the core of wallettes. Three replicates of wallettes specimens with dimension 600 mm width and 600 mm length were fabricated without surface plaster and with 16 mm thickness of surface plaster. The wallettes were tested under axial compression load after 28 days of fabrication until failure. The result indicated that, the application of surface plaster significantly increases the loading capacity about 35 % and different orientation of the panels improve the bonding strength of the wall.
Mode division multiplexing technology for single-fiber optical trapping axial-position adjustment.
Liu, Zhihai; Wang, Lei; Liang, Peibo; Zhang, Yu; Yang, Jun; Yuan, Libo
2013-07-15
We demonstrate trapped yeast cell axial-position adjustment without moving the optical fiber in a single-fiber optical trapping system. The dynamic axial-position adjustment is realized by controlling the power ratio of the fundamental mode beam (LP01) and the low-order mode beam (LP11) generated in a normal single-core fiber. In order to separate the trapping positions produced by the two mode beams, we fabricate a special fiber tapered tip with a selective two-step method. A yeast cell of 6 μm diameter is moved along the optical axis direction for a distance of ~3 μm. To the best of our knowledge, this is the first demonstration of the trapping position adjustment without moving the fiber for single-fiber optical tweezers. The excitation and utilization of multimode beams in a single fiber constitutes a new development for single-fiber optical trapping and makes possible more practical applications in biomedical research fields.
Directory of Open Access Journals (Sweden)
Ali Ghorbanpour Arani
2017-07-01
Full Text Available In the present research, vibration and instability of axially moving sandwich plate made of soft core and composite face sheets under initial tension is investigated. Single-walled carbon nano-tubes (SWCNTs are selected as a reinforcement of composite face sheets inside Poly methyl methacrylate (PMMA matrix. Higher order shear deformation theory (HSDT is utilized due to its accuracy of polynomial functions than other plate theories. Based on extended rule of mixture, the structural properties of composite face sheets are taken into consideration. Motion equations are obtained by means of Hamilton’s principle and solved analytically. Influences of various parameters such as axially moving speed, volume fraction of CNTs, pre-tension, thickness and aspect ratio of sandwich plate on the vibration characteristics of moving system are discussed in details. The results indicated that the critical speed of moving sandwich plate is strongly dependent on the volume fraction of CNTs. Therefore, the critical speed of moving sandwich plate can be improved by adding appropriate values of CNTs. The results of this investigation can be used in design and manufacturing of marine vessels and aircrafts.
Fracture analysis of axially cracked pressure tube of pressurized heavy water reactor
Energy Technology Data Exchange (ETDEWEB)
Krishnan, S.; Bhasin, V.; Mahajan, S.C. [Bhabha Atomic Research Centre, Bombay (India)] [and others
1997-04-01
Three Dimensional (313) finite element elastic plastic fracture analysis was done for through wall axially cracked thin pressure tubes of 220 MWe Indian Pressurized Heavy Water Reactor. The analysis was done for Zr-2 and Zr-2.5Nb pressure tubes operating at 300{degrees}C and subjected to 9.5 Mpa internal pressure. Critical crack length was determined based on tearing instability concept. The analysis included the effect of crack face pressure due to the leaking fluid from tube. This effect was found to be significant for pressure tubes. The available formulae for calculating J (for axially cracked tubes) do not take into account the effect of crack face pressure. 3D finite element analysis also gives insight into variation of J across the thickness of pressure tube. It was observed that J is highest at the mid-surface of tube. The results have been presented in the form of across the thickness average J value and a peak factor on J. Peak factor on J is ratio of J at mid surface to average J value. Crack opening area for different cracked lengths was calculated from finite element results. The fracture assessment of pressure tubes was also done using Central Electricity Generating Board R-6 method. Ductile tearing was considered.
Reassessing the Plastic Hinge Model for Energy Dissipation of Axially Loaded Columns
Directory of Open Access Journals (Sweden)
R. M. Korol
2014-01-01
Full Text Available This paper investigates the energy dissipation potential of axially loaded columns and evaluates the use of a plastic hinge model for analysis of hi-rise building column collapse under extreme loading conditions. The experimental program considered seven axially loaded H-shaped extruded aluminum structural section columns having slenderness ratios that would be typical of floor-to-ceiling heights in buildings. All seven test specimens initially experienced minor-axis overall buckling followed by formation of a plastic hinge at the mid-height region, leading to local buckling of the flanges on the compression side of the plastic hinge, and eventual folding of the compression flanges. The experimental energy absorption, based on load-displacement relations, was compared to the energy estimates based on section plastic moment resistance based on measured yield stress and based on measured hinge rotations. It was found that the theoretical plastic hinge model underestimates a column’s actual ability to absorb energy by a factor in the range of 3 to 4 below that obtained from tests. It was also noted that the realizable hinge rotation is less than 180°. The above observations are based, of course, on actual columns being able to sustain high tensile strains at hinge locations without fracturing.
Determination of the axial-vector form factor in the radiative decay of the pion
International Nuclear Information System (INIS)
Ortendahl, D.A.
1976-12-01
The branching ratio for the decay π → eνγ was measured in a counter experiment in which the e + was detected in a magnetic spectrometer and the γ-ray in a lead glass hodoscope. The number of observed events is 226.2 +- 22.4. The branching ratio into the phase space with electron momentum above 56 MeV/c and the electron/photon opening angle greater than 132 0 is found to be (5.6 +- 0.7) x 10 -8 . From the measured branching ratio one determines γ, the ratio of the axial vector to vector form factor. The vector form factor is computed using CVC and the π 0 lifetime. For T/sub π/ 0 = 0.828 x 10 -16 sec, γ = 0.44 +- 0.12 or γ = --2.36 +- 0.12 is obtained. A comparison between the measured values of γ and various theories is made
Directory of Open Access Journals (Sweden)
A. S. Laskin
2015-01-01
Full Text Available The article presents the results of numerical investigation of kinetic energy (KE loss and blading efficiency of the single-stage axial turbine under different operating conditions, characterized by the ratio u/C0. The calculations are performed by stationary (Stage method and nonstationary (Transient method methods using ANSYS CFX. The novelty of this work lies in the fact that the numerical simulation of steady and unsteady flows in a turbine stage is conducted, and the results are obtained to determine the loss of KE, both separately by the elements of the flow range and their total values, in the stage efficiency as well. The results obtained are compared with the calculated efficiency according to one-dimensional theory.To solve these problems was selected model of axial turbine stage with D/l = 13, blade profiles of rotor and stator of constant cross-section, similar to tested ones in inverted turbine when = 0.3. The degree of reactivity ρ = 0.27, the rotor speed was varied within the range 1000 ÷ 1800 rev/min.Results obtained allow us to draw the following conclusions:1. The level of averaged coefficients of total KE losses in the range of from 0.48 to 0.75 is from 18% to 21% when calculating by the Stage method and from 21% to 25% by the Transient one.2. The level of averaged coefficients of KE losses with the output speed of in the specified range is from 9% to 13%, and almost the same when in calculating by Stage and Transient methods.3. Levels of averaged coefficients of KE loss in blade tips (relative to the differential enthalpies per stage are changed in the range: from 4% to 3% (Stage and are stored to be equal to 5% (Transient; from 5% to 6% (Stage and from 6% to 8% (Transient.4. Coefficients of KE losses in blade tips GV and RB are higher in calculations of the model stage using the Transient method than the Stage one, respectively, by = 1.5 ÷ 2.5% and = 4 ÷ 5% of the absolute values. These are values to characterize the KE
Behaviour of partially composite precast concrete sandwich panels under flexural and axial loads
Tomlinson, Douglas George
Precast concrete sandwich panels are commonly used on building exteriors. They are typically composed of two concrete wythes that surround rigid insulation. They are advantageous as they provide both structural and thermal resistance. The structural response of sandwich panels is heavily influenced by shear connectors that link the wythes together. This thesis presents a study on partially composite non-prestressed precast concrete wall panels. Nine flexure tests were conducted on a wall design incorporating 'floating' concrete studs and Glass Fibre Reinforced Polymer (GFRP) connectors. The studs encapsulate and stiffen the connectors, reducing shear deformations. Ultimate loads increased from 58 to 80% that of a composite section as the connectors' reinforcement ratio increased from 2.6 to 9.8%. This design was optimized by reinforcing the studs and integrating them with the structural wythe; new connectors composed of angled steel or Basalt-FRP (BFRP) were used. The load-slip response of the new connector design was studied through 38 double shear push-through tests using various connector diameters and insertion angles. Larger connectors were stronger but more likely to pull out. Seven flexure tests were conducted on the new wall design reinforced with different combinations of steel and BFRP connectors and reinforcement. Composite action varied from 50 to 90% depending on connector and reinforcement material. Following this study, the axial-bending interaction curves were established for the new wall design using both BFRP and steel connectors and reinforcement. Eight panels were axially loaded to predesignated loads then loaded in flexure to failure. A technique is presented to experimentally determine the effective centroid of partially composite sections. Beyond the tension and compression-controlled failure regions of the interaction curve, a third region was observed in between, governed by connector failure. Theoretical models were developed for the bond
International Nuclear Information System (INIS)
Wittenberg, R.; Vliet, J.W. van; Ghaye, B.; Peters, J.F.; Schaefer-Prokop, C.M.; Coche, E.
2012-01-01
Purpose: Compare the right ventricle to left ventricle (RV/LV) diameter ratio obtained from axial pulmonary CT angiograms (CTPA) with those derived from automatically generated 4-chamber (4-CH) reformats in patients with suspected pulmonary embolism (PE). Methods: In this institutional review board-approved study we included 120 consecutive non ECG-gated CTPA from 3 institutions (mean age 60 ± 16 years; 71 women). Twenty 64-slice CTPA with PE and 20 without PE were selected per institution. For each patient the RV/LV diameter ratio was obtained from both axial CTPA images and automatically generated 4-CH reformats. Measurements were performed twice in two separated sessions by 2 experienced radiologists and 2 residents. The differences between the measurements on both views were evaluated. Results: The 4-CH view was successfully obtained in 113 patients. The mean axial and 4-CH diameter ratios were comparable for three of the four readers (p = 0.56, p = 0.13, p = 0.08). Although the mean diameters (1.0 and 1.03 respectively) for one resident were significantly different (p = 0.013), the difference of 0.03 seems negligible in clinical routine. Three readers achieved equally high intra-reader agreements with both measurements (ICCs of 0.94, 0.95 and 0.96), while one reader showed a different variability with ICCs of 0.96 for the axial view and 0.91 for the 4-CH view. The inter-reader agreement was equally high for both measurement types with ICCs of 0.95 and 0.94, respectively. Conclusion: In patients with suspected PE, RV/LV diameters ratio can be measured with the same reproducibility and accuracy using an automatically generated 4-CH view compared to the axial view.
Deep axial reflux, an important contributor to skin changes or ulcer in chronic venous disease.
Danielsson, Gudmundur; Eklof, Bo; Grandinetti, Andrew; Lurie, Fedor; Kistner, Robert L
2003-12-01
We undertook this cross-sectional study to investigate the distribution of venous reflux and effect of axial reflux in superficial and deep veins and to determine the clinical value of quantifying peak reverse flow velocity and reflux time in limbs with chronic venous disease. Four hundred one legs (127 with skin changes, 274 without skin changes) in 272 patients were examined with duplex ultrasound scanning, and peak reverse flow velocity and reflux time were measured. Both parameters were graded on a scale of 0 to 4. The sum of reverse flow scores was calculated from seven venous segments, three in superficial veins (great saphenous vein at saphenofemoral junction, great saphenous vein below knee, small saphenous vein) and four in deep veins (common femoral vein, femoral vein, deep femoral vein, popliteal vein). Axial reflux was defined as reflux in the great saphenous vein above and below the knee or in the femoral vein to the popliteal vein below the knee. Reflux parameters and presence or absence of axial reflux in superficial or deep veins were correlated with prevalence of skin changes or ulcer (CEAP class 4-6). The most common anatomic presentation was incompetence in all three systems (superficial, deep, perforator; 46%) or in superficial or perforator veins (28%). Isolated reflux in one system only was rare (15%; superficial, 28 legs; deep, 14 legs; perforator, 18 legs). Deep venous incompetence was present in 244 legs (61%). If common femoral vein reflux was excluded, prevalence of deep venous incompetence was 52%. The cause, according to findings at duplex ultrasound scanning, was primary in 302 legs (75%) and secondary in 99 legs (25%). Presence of axial deep venous reflux increased significantly with prevalence of skin changes or ulcer (C4-C6; odds ratio [OR], 2.7; 95% confidence interval [CI], 1.56-4.67). Of 110 extremities with incompetent popliteal vein, 81 legs had even femoral vein reflux, with significantly more skin changes or ulcer, compared
So, Hyok; Pan, Dong; Li, Lixia; Zhao, Jianhua
2017-03-01
Epitaxial high-quality InAs/InSb axial heterostructure nanowires are of great interest due to their distinct advantages in fundamental research as well as applications in semiconductor electronic and quantum devices. Currently, nearly all the growth of InAs/InSb axial heterostructure nanowires is assisted with foreign catalysts such as Au, and work on foreign-catalyst-free growth of InAs/InSb axial heterostructure nanowires is lacking. Here we report on the growth of InAs/InSb axial heterostructure nanowires on Si (111) substrates by molecular-beam epitaxy without using any foreign catalysts. The Sb/In beam equivalent pressure (BEP) ratio is found to have important influence on the heterostructure nanowire morphology, and InSb nanowires can be epitaxially grown on InAs nanowire stems with a hexagonal prism and nanosheet-like shapes when the Sb/In BEP ratio varies from 10 to 20. Transmission electron microscopy studies reveal that the InAs nanowire stems have a mixture of zincblende (ZB) and wurtzite (WZ) crystal structures, while InSb nanowire parts have a pure ZB crystal structure free of stacking faults. Composition analysis of axial heterostructure nanowires provides clear evidence that the InSb nanowires are epitaxially grown on InAs nanowires in an In self-assisted vapor-liquid-solid manner. This study paves a new route for growing narrow-gap semiconductor heterostructures with strong spin-orbit interaction for the study of topological states, and the growth manner presented here is expected to be used to grow other In-based axial heterostructure nanowires.
Directional gear ratio transmissions
Lafever, A. E. (Inventor)
1984-01-01
Epicyclic gear transmissions which transmit output at a gear ratio dependent only upon the input's direction are considered. A transmission housing envelops two epicyclic gear assemblies, and has shafts extending from it. One shaft is attached to a sun gear within the first epicyclic gear assembly. Planet gears are held symmetrically about the sun gear by a planet gear carrier and are in mesh with both the sun gear and a ring gear. Two unidirectional clutches restrict rotation of the first planet gear carrier and ring gear to one direction. A connecting shaft drives a second sun gear at the same speed and direction as the first planet gear carrier while a connecting portion drives a second planet gear carrier at the same speed and direction as the first ring gear. The transmission's output is then transmitted by the second ring gear to the second shaft. Input is transmitted at a higher gear ratio and lower speed for all inputs in the first direction than in the opposite direction.
Axial segregation in spherical and cylindrical rotating tumblers
Directory of Open Access Journals (Sweden)
D’Ortona Umberto
2017-01-01
Full Text Available Monodisperse and bidisperse granular flows are studied in rotating tumblers using DEM. In spherical tumblers, flowing particles’ trajectories do not follow straight lines but are curved. At the same time particles near the surface drift toward the pole, inducing two global recirculation cells. Combined with radial segregation, drift and curvature compete to impose the axial segregation pattern: Small-Large-Small (SLS or Large-Small-Large (LSL. Fill level, rotation speed and wall roughness influence drift and curvature, and modify the resulting segregation pattern. In cylindrical tumblers, equivalent recirculation cells occur next to the end walls. A second pair of recirculation cells with a weak drift in the opposite direction appears at the center for long enough tumblers. Unlike the sphere case, curvature and drift in the primary cells combine to push large particles toward the end walls, explaining why large particle bands appear at the end walls for axial segregation in cylinder.
Classical theory of the Kumakhov radiation in axial channeling
International Nuclear Information System (INIS)
Khokonov, M.K.; Komarov, F.F.; Telegin, V.I.
1984-01-01
The paper considers radiation of ultrarelativistic electrons in axial channeling initially predicted by Kumakhov. The consideration is based on the results of solution of the Fokker-Planck equation. The spectral-angular characteristics of the Kumakhov radiation in thick single crystals are calculated. It is shown that in heavy single crystals the energy losses on radiation can amount to a considerable portion of the initial beam energy. The possibility of a sharp increase of radiation due to a decrease of crystal temperature is discussed. It is shown that radiation intensity in axial channeling is weakly dependent on the initial angle of the electron entrance into the channel if this angle changes within the limits of a critical one. (author)
Impaired bed mobility: quantitative torque analysis with axial inertial sensors.
Bhidayasiri, Roongroj; Sringean, Jirada; Thanawattano, Chusak
2017-08-01
Difficulty in turning in bed is rated as the most troublesome night-time symptom among Parkinson's disease (PD) patients. To develop a practical objective method for home assessment of a patient's ability to turn in bed. Nocturnal parameters and torque of self-turning in bed from 17 PD couples were assessed and compared using a wearable axial sensor for two nights in their homes. The torque of axial rotation which indicates the ability of PD patients to turn in bed was significantly less than their spouses (p turning in bed and total unified Parkinson's Disease Rating Scale score (r = 0.71; p = 0.001), and total Nocturnal Akinesia Dystonia and Cramp score (r = 0.634; p = 0.006). Our study confirms a decreased ability in turning in PD.
Vector and axial nucleon form factors: A duality constrained parameterization
International Nuclear Information System (INIS)
Bodek, A.; Avvakumov, S.; Bradford, R.; Budd, H.
2008-01-01
We present new parameterizations of vector and axial nucleon form factors. We maintain an excellent descriptions of the form factors at low momentum transfers, where the spatial structure of the nucleon is important, and use the Nachtman scaling variable ξ to relate elastic and inelastic form factors and impose quark-hadron duality constraints at high momentum transfers where the quark structure dominates. We use the new vector form factors to re-extract updated values of the axial form factor from neutrino experiments on deuterium. We obtain an updated world average value from ν μ d and pion electroproduction experiments of M A =1.014±0.014 GeV/c 2 . Our parameterizations are useful in modeling neutrino interactions at low energies (e.g. for neutrino oscillations experiments). The predictions for high momentum transfers can be tested in the next generation electron and neutrino scattering experiments. (orig.)
Computerized axial tomography : the tool in osseointegrated dental implants
International Nuclear Information System (INIS)
Fernandez-Lopez, Otton
2002-01-01
Failure rates in rehabilitations with osseointegrated implants are handled through appropriate radiographic preoperative planning. The appropriate length of the implant without running the risk of a perforation of vital structures, has been determined by a radiographic diagnosis. Computerized and conventional axial tomography have proved to be invaluable elements for pre-surgical evaluation. A radiologic guidance is elaborated to perform a computerized axial tomography (CT) of maxillary bones in totally edentulous patients. Surgical guides are constructed from a wax-up emanated from the information of the CT. The CT has proven to be an radiographic indispensable element to achieve the surgical-prosthetic success in osseointegrated dental implants. The CT has allowed the realization of a precise wax-up for making of surgical guide and a precise temporary prostheses in positioning of osseointegrated implants, with the consequent saving time and money for the rehabilitator and patient [es
[Inflammatory spinal diseases: axial spondyloarthritis : Central importance of imaging].
Baraliakos, X; Fruth, M; Kiltz, U; Braun, J
2017-03-01
The diagnosis of axial spondyloarthritis (axSpA) includes classical ankylosing spondylitis (AS) as well as earlier stages and abortive courses of the disease, in which structural alterations have not yet occurred. These are classified as non-radiographic axSpA (nr-axSpa). Inflammatory changes in the entire axial skeleton are characteristic for axSpA and can be visualized by magnetic resonance imaging (MRI), while in most patients structural alterations, such as new bone formation with syndesmophytes and ankylosis develop in the later course of the disease. These bony alterations can best be visualized by conventional radiography and by computed tomography. Certain MRI sequences are nowadays considered as the standard method for depiction of inflammatory changes in axSpA. The introduction of MRI has led to a paradigm shift for this disease because the inflammatory lesions characteristic for the disease can be visualized at an early stage using appropriate MRI sequences.
Organocatalyzed Asymmetric Synthesis of Axially, Planar, and Helical Chiral Compounds.
Shirakawa, Seiji; Liu, Shiyao; Kaneko, Shiho
2016-02-04
Axially, planar, and helical chiral compounds are indispensable building blocks in modern organic synthesis. A wide variety of chiral ligands and catalysts were designed based on these chiral scaffolds, and these chiral ligands and catalysts were used for various catalytic asymmetric transformations to produce important chiral compounds in an optically enriched form. Furthermore, these chiral skeletons are found in the structure of biologically active natural products. Thus, the development of efficient enantioselective methods for the synthesis of these chiral compounds is an important task in the field of organic chemistry. In the last few years, organocatalyzed approaches, which are one of the most reliable catalytic asymmetric methods, became a hot topic. This Focus Review summarizes asymmetric organocatalytic methods for the synthesis of axially, planar, and helical chiral compounds as useful chiral building blocks. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
An Axial Sliding Test for machine elements surfaces
DEFF Research Database (Denmark)
Godi, Alessandro; Grønbæk, J.; Mohaghegh, Kamran
2012-01-01
are necessary: a press to provide the normal pressure and a tensile machine to perform the axial movements. The test is calibrated so that the correspondence between the normal pressure and the container advancement is found. Finally, preliminary tests are carried out involving a multifunctional and a fine......Throughout the years, it has become more and more important to find new methods for reducing friction and wear occurrence in machine elements. A possible solution is found in texturing the surfaces under tribological contact, hence the development and spread of plateau-honed surface for cylinder...... liners. To prove the efficacy of a particular textured surface, it is paramount to perform experimental tests under controlled laboratory conditions. In this paper a new test rig simulating pure sliding conditions is presented, dubbed Axial Sliding Test. It presents four major components: a rod, a sleeve...
Buckling Imperfection Sensitivity of Axially Compressed Orthotropic Cylinders
Schultz, Marc R.; Nemeth, Michael P.
2010-01-01
Structural stability is a major consideration in the design of lightweight shell structures. However, the theoretical predictions of geometrically perfect structures often considerably over predict the buckling loads of inherently imperfect real structures. It is reasonably well understood how the shell geometry affects the imperfection sensitivity of axially compressed cylindrical shells; however, the effects of shell anisotropy on the imperfection sensitivity is less well understood. In the present paper, the development of an analytical model for assessing the imperfection sensitivity of axially compressed orthotropic cylinders is discussed. Results from the analytical model for four shell designs are compared with those from a general-purpose finite-element code, and good qualitative agreement is found. Reasons for discrepancies are discussed, and potential design implications of this line of research are discussed.
Involvement of the axial skeleton in psoriatic arthritis
Directory of Open Access Journals (Sweden)
E. E. Gubar
2017-01-01
Full Text Available The involvement of the spine in psoriatic arthritis (PsA is observed in a large number of cases; however, a unified approach to solving this problem has not yet been formed. Criteria for the diagnosis of psoriatic spondylitis have not been clearly defined; internationally accepted definitions for this concept are absent; criteria for a PsA exacerbation and remission have not been formulated with regard to spondylitis. The specialists of GRAPPA (Group for Research and Assessment of Psoriasis and Psoriatic Arthritis have no their own recommendations for the treatment of axial involvement in PsA now. The therapeutic tactics used in the treatment of axial spondylitis and ankylosing spondylitis is borrowed in this area. The involvement of the spine calls for further investigation.
Buckling localization in a cylindrical panel under axial compression
DEFF Research Database (Denmark)
Tvergaard, Viggo; Needleman, A.
2000-01-01
Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile...... test specimens is discussed in general. For the cylindrical panel, it is shown that buckling localization develops shortly after a maximum load has been attained, and this occurs for a purely elastic panel as well as for elastic-plastic panels. In a case where localization occurs after a load maximum......, but where subsequently the load starts to increase again, it is found that near the local load minimum, the buckling pattern switches back to a periodic type of pattern. The inelastic material behavior of the panel is described in terms of J(2) corner theory, which avoids the sometimes unrealistically high...
Accuracy Improvement of Axial Power Shape Reconstruction Using GMDH Algorithm
Energy Technology Data Exchange (ETDEWEB)
Yum, Seongpil; Kim, Jaemin; Park, Minyong; Choe, Jiwon; Zhang, Peng; Lee, Deokjung [UNIST, Ulsan (Korea, Republic of); Shin, Ho Cheol [KHNP CRI, Daejeon (Korea, Republic of)
2016-10-15
This paper applies Group Method of Data Handling (GMDH) algorithm to improve the reconstruction accuracy. Reference three-dimensional power distributions are generated for Shinkori Unit 1 Cycle 3 by simulating Xe transients in BOC, MOC, and EOC, which include saddle, top- and bottom-skewed shapes. Using these power distributions, the axial power distributions were reconstructed by GMDH and the 5th order Fourier series method. It was shown that GMDH algorithm reduced the average Root-Mean-Square-Error (RMSE) from 1.01% of Fourier series method, down to 0.17%. This paper presents the accuracy improvement of axial power reconstruction using GMDH algorithm with the first order polynomial basis function compared to the COLSS Fourier series expansion algorithm.
Axial weak currents in the Wess-Zumino term
International Nuclear Information System (INIS)
Fujikawa, Kazuo
1986-01-01
In a simplified model lagrangian of 3 quarks with an SU(2)sub(L) gauging of chiral SU(3)sub(L)xSU(3)sub(R) to introduce W-boson, we analyse certain complications associated with the low-energy theorem including axial weak fields. We first show that the low-energy amplitude is independent of the form of the quark-level anomalous identity, whether in the covariant form or the consistent form. However, the interplay of the short-distance dynamics (anomalous identity) and the long-distance dynamics (low-energy theorem) becomes involved in the presence of axial fields. We then discuss what kinds of conditions single out the gauged Wess-Zumino term as a low-energy effective action. The connection of the low-energy theorem with the 't Hooft anomaly matching condition is also discussed. (orig.)
Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades
Directory of Open Access Journals (Sweden)
Li Yang
2007-01-01
Full Text Available This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP neural network and genetic algorithm (GA, the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pressure ratio, stable operating range, and aerodynamic noise. Detailed flow measurement was performed in outlet flow field for investigating the responsible flow mechanisms. The optimized blade can cause a spanwise redistribution of flow toward the blade midspan and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at midspan. In addition, the measured spectrums show that the broadband noise of the impeller is dominant.
Laser anemometer measurements in a transonic axial-flow fan rotor
Strazisar, Anthony J.; Wood, Jerry R.; Hathaway, Michael D.; Suder, Kenneth L.
1989-01-01
Laser anemometer surveys were made of the 3-D flow field in NASA rotor 67, a low aspect ratio transonic axial-flow fan rotor. The test rotor has a tip relative Mach number of 1.38. The flowfield was surveyed at design speed at near peak efficiency and near stall operating conditions. Data is presented in the form of relative Mach number and relative flow angle distributions on surfaces of revolution at nine spanwise locations evenly spaced from hub to tip. At each spanwise location, data was acquired upstream, within, and downstream of the rotor. Aerodynamic performance measurements and detailed rotor blade and annulus geometry are also presented so that the experimental results can be used as a test case for 3-D turbomachinery flow analysis codes.
Dynamics of tubular cylindrical structures in axial flow.
Paidoussis, Michael P.
2017-01-01
The dynamics of slender cylinders in axial flow subject to conventional boundary conditions is recalled first. This is followed by brief reviews and discussion of new developments in (i) the dynamics of unconventionally supported cylinders, e.g. cylinders free at the upstream end and supported at the downstream one, (ii) the dynamics of cylinders subject to both internal and external flow for applications in oil and gas drilling and production, as well as hydrocarbon storage in salt-mined cav...
Experimental investigations on an axial grooved cryogenic heat pipe
Directory of Open Access Journals (Sweden)
Senthil Kumar Muniappan
2012-01-01
Full Text Available This paper deals with development and studies of a trapezoidal axial grooved nitrogen heat pipe. A special liquid nitrogen cryostat has been designed and developed for evaluating the performance of heat pipe where the condenser portion is connected to the cold sink externally. Experiments have been performed on the heat pipe as well as on an equivalent diameter copper rod at different heat loads. The steady state performance of the heat pipe is compared with that of copper rod.
Axially symmetric domain wall in 2+1-dimensions
International Nuclear Information System (INIS)
Soda, Jiro; Yamanaka, Yuki.
1991-04-01
An axially symmetric domain wall (string) in 2+1-dimensions is investigated in the synchronous gauge. This problem is also regarded as a cylindrical symmetric domain wall (membrane) in 3+1-dimensions. Using Israel's method, we present a general solution. As a special case, a static solution is obtained which agrees with the previous result of Deser and Jackiw obtained by another method. (author)
Axially symmetric, stationary gravitational field equations and pseudospherical surfaces
International Nuclear Information System (INIS)
Tomimatsu, Akira.
1981-04-01
For axially symmetric, stationary gravitational field equations, a new Lax pair of the inverse scattering method is presented from a geometrical point of view. The metric coefficient e sup(2γ) (= -g sub(rho rho)g sub(tt)sup(-1)) is taken as the basic field variable, which satisfies an equation describing pseudospherical surfaces, i.e., surfaces of constant negative Gaussian curvature. The equations for other metric coefficients are also discussed. (author)
Overview of the Axial Field Spectrometer in the ISR tunnel
1980-01-01
A view of the Axial Field Spectrometer – the last large experiment at the ISR. The horizontal top and vertical outer arrays of the uranium-scintillator hadron calorimeter are clear to be seen, with the blue cylindrical pole piece of the magnet just visible. The pipes that are visible in front of the pole piece are cryogenic feed pipes for the superconducting low-beta quadrupoles.
Colonic surveillance by CT colonography using axial images only
International Nuclear Information System (INIS)
Bruzzi, John F.; Brennan, Darren D.; Fenlon, Helen M.; Moss, Alan C.; MacMathuna, Padraic
2004-01-01
Patients at increased risk of colon cancer require strict colon surveillance. Our objective was to establish the efficacy of 2D axial CT colonography as a surveillance test when performed in routine clinical practice. Eighty-two patients at increased risk of colon cancer underwent CT colonography followed by conventional colonoscopy on the same morning. CT colonography studies were performed on a four-ring multidetector CT scanner (100 mAs, 120 kVp, 4 x 2.5 collimation) and were interpreted by two radiologists using 2D axial images only. Results were correlated with findings at colonoscopy. Note was made of subsequent histology reports from polypectomy specimens. A total of 52 polyps were detected at colonoscopy. Using 2D axial images alone, with no recourse to 2D multiplanar or 3D views, the sensitivity of CT colonography was 100, 33 and 19% for polyps larger than 9, 6-9 and smaller than 6 mm, respectively. Per-patient specificities were 98.8, 96 and 81.5%, respectively. Twenty-nine percent of polyps smaller than 1 cm were adenomatous and there were no histological features of severe dysplasia. CT colonography is a useful colon surveillance tool for patients at increased risk of colon cancer. It has a high specificity for identifying patients who should proceed to colonoscopy and polypectomy, while allowing further colon examination to be deferred in patients with normal studies. Using 2D axial images only, CT colonography can be performed as part of the daily CT workload, with a very low rate of referral for unnecessary colonoscopy. (orig.)
Numerical analysis of a microwave torch with axial gas injection
Energy Technology Data Exchange (ETDEWEB)
Gritsinin, S. I.; Davydov, A. M.; Kossyi, I. A., E-mail: kossyi@fpl.gpi.ru [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Kulumbaev, E. B. [National Research University Belgorod State University (Russian Federation); Lelevkin, V. M. [Kyrgyz-Russian Slavic University (Kyrgyzstan)
2013-07-15
The characteristics of a microwave discharge in an argon jet injected axially into a coaxial channel with a shortened inner electrode are numerically analyzed using a self-consistent equilibrium gas-dynamic model. The specific features of the excitation and maintenance of the microwave discharge are determined, and the dependences of the discharge characteristics on the supplied electromagnetic power and gas flow rate are obtained. The calculated results are compared with experimental data.
One-loop corrections to the baryon axial vector current
Indian Academy of Sciences (India)
2012-10-06
Oct 6, 2012 ... 917–920. One-loop corrections to the baryon axial vector current. M A HERNÁNDEZ-RUÍZ1,2. 1Instituto de Física, Universidad Autónoma de San Luis Potosí,. Av. Manuel Nava 6 Zona Universitaria 78290, San Luis Potosí SLP, México. 2Facultad de Ciencias Químicas, Universidad Autónoma de Zacatecas,.
Taming axial dispersion in hydrodynamic chromatography columns through wall patterning
Adrover, Alessandra; Cerbelli, Stefano; Giona, Massimiliano
2018-04-01
A well-known limitation of hydrodynamic chromatography arises from the synergistic interaction between transverse diffusion and streamwise convection, which enhances axial dispersion through the Taylor-Aris mechanism. We show that a periodic sequence of slip/no-slip conditions at the channel walls (e.g., representing wall indentations hosting stable air pockets) can significantly reduce axial dispersion, thus enhancing separation performance. The theoretical/numerical analysis is based on a generalization of Brenner's macrotransport approach to solute transport, here modified to account for the finite-size of the suspended particles. The most effective dispersion-taming outcome is observed when the alternating sequence of slip/no-slip conditions yields non-vanishing cross-sectional flow components. The combination of these components with the hindering interaction between the channel boundaries and the finite-sized particles gives rise to a non-trivial solution of Brenner's problem on the unit periodic cell, where the cross-sectional particle number density departs from the spatially homogeneous condition. In turn, this effect impacts upon the solution of the so-called b-field defining the large-scale dispersion tensor, with an overall decremental effect on the axial dispersion coefficient and on the Height Equivalent of a Theoretical Plate.
Fundamental metallurgical aspects of axial splitting in zircaloy cladding
International Nuclear Information System (INIS)
Chung, H. M.
2000-01-01
Fundamental metallurgical aspects of axial splitting in irradiated Zircaloy cladding have been investigated by microstructural characterization and analytical modeling, with emphasis on application of the results to understand high-burnup fuel failure under RIA situations. Optical microscopy, SEM, and TEM were conducted on BWR and PWR fuel cladding tubes that were irradiated to fluence levels of 3.3 x 10 21 n cm -2 to 5.9 x 10 21 n cm -2 (E > 1 MeV) and tested in hot cell at 292--325 C in Ar. The morphology, distribution, and habit planes of macroscopic and microscopic hydrides in as-irradiated and posttest cladding were determined by stereo-TEM. The type and magnitude of the residual stress produced in association with oxide-layer growth and dense hydride precipitation, and several synergistic factors that strongly influence axial-splitting behavior were analyzed. The results of the microstructural characterization and stress analyses were then correlated with axial-splitting behavior of high-burnup PWR cladding reported for simulated-RIA conditions. The effects of key test procedures and their implications for the interpretation of RIA test results are discussed
Imaging results and TOF studies with axial PET detectors
Joram, Christian
2013-01-01
We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the held of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The Fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations ( <2 mm FWHM in all three coordinates over the complete held of view) and also demonstrated the ability to include Compton interactions (inter-cr...
Imaging results and TOF studies with axial PET detectors
Joram, Christian
2013-12-01
We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the field of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations (PET concept making use of the novel digital SiPM detectors by Philips. After reproducing comparable energy and spatial resolution on a small digital AX-PET set-up with 100 mm long crystals, we demonstrated a coincidence resolving time of about 210 ps FWHM.
Multi technical analysis of wear mechanisms in axial piston pumps
Schuhler, G.; Jourani, A.; Bouvier, S.; Perrochat, J.-M.
2017-05-01
Axial piston pumps convert a motor rotation motion into hydraulic or pneumatic power. Their compactness and efficiency of approximately 0.9 make them suitable for actuation applications especially in aeronautics. However, they suffer a limited life due to the wear of their components. In the literature, studies of axial piston pumps deal with contact between its different elements under lubrication conditions. Nevertheless, they are more focused on analytic or numerical approaches. This study consists in an experimental analysis of worn pump components to highlight and understand wear mechanisms. Piston shoes are central components in the axial piston pump since they are involved in three tribological contacts. These three contacts are thereby studied: piston shoes/swashplate, piston shoes/pistons and piston shoes/shoes hold down plate (SHDP). To perform this analysis, helicopter hydraulic pumps after different operating times have been studied. The wear damage mechanisms and wear debris are analysed using SEM observations. 3D surface roughness measurements are then used to characterize worn surfaces. The observations reveal that in the contact between shoes and swashplate, the main wear mechanism is three-body abrasive wear due to coarse carbides removal. Between shoes and pistons, wear occurs in a less severe way and is mainly due to the debris generated in the first contact and conveyed by the lubricating fluid. In the third contact, the debris are also the prime cause of the abrasive wear and the generation of deep craters in the piston shoes.
Simultaneous Rotational and Axial Flow of Nonlinear Fluids
Ashrafi, Nariman; Yektapour, Mehdi; Shafahi, Mehdi
2017-11-01
An axial flow is introduced to the rotational flow of pseudoplastic fluids in the gap between concentric cylinders. The outer cylinder is fixed while the inner one has simultaneous and independent rotational and translational motions. The fluid follows the Carreau-Bird model and mixed boundary conditions are imposed. The four-dimensional low-order equations resulted from Galerkin projection of the conservation of mass and momentum equations, includes highly non-linear terms in the velocity components. Without axial flow, stability of the base radial flow is lost to the vortex structure at a lower critical Taylor number, with increase of the fluid pseudoplasticity. The vortices imply onset of a supercritical bifurcation which occurs in the rotational flow of linear fluids as well. In contrast to the Newtonian case, pseudoplastic Taylor vortices lose their stability at a second critical Taylor number is reached a second critical number that corresponds to the onset of a Hopf bifurcation. The axial flow, caused by the translational motion of the inner cylinder advance each critical point on the bifurcation diagram. The flow field and viscosity maps are provided for major stability regions.
Behavior of unbonded flexible risers subject to axial tension
Ren, Shao-fei; Tang, Wen-yong; Guo, Jin-ting
2014-04-01
Owing to nonlinear contact problems with slip and friction, a lot of limiting assumptions are made when developing analytical models to simulate the behavior of an unbonded flexible riser. Meanwhile, in order to avoid convergence problems and excessive calculating time associated with running the detailed finite element (FE) model of an unbonded flexible riser, interlocked carcass and zeta layers with complicated cross section shapes are replaced by simple geometrical shapes (e.g. hollow cylindrical shell) with equivalent orthotropic materials. But the simplified model does not imply the stresses equivalence of these two layers. To solve these problems, based on ABAQUS/Explicit, a numerical method that is suitable for the detailed FE model is proposed. In consideration of interaction among all component layers, the axial stiffness of an eight-layer unbonded flexible riser subjected to axial tension is predicted. Compared with analytical and experimental results, it is shown that the proposed numerical method not only has high accuracy but also can substantially reduce the calculating time. In addition, the impact of the lay angle of helical tendons on axial stiffness is discussed.
HTS axial flux induction motor with analytic and FEA modeling
International Nuclear Information System (INIS)
Li, S.; Fan, Y.; Fang, J.; Qin, W.; Lv, G.; Li, J.H.
2013-01-01
Highlights: •A high temperature superconductor axial flux induction motor and a novel maglev scheme are presented. •Analytic method and finite element method have been adopted to model the motor and to calculate the force. •Magnetic field distribution in HTS coil is calculated by analytic method. •An effective method to improve the critical current of HTS coil is presented. •AC losses of HTS coils in the HTS axial flux induction motor are estimated and tested. -- Abstract: This paper presents a high-temperature superconductor (HTS) axial-flux induction motor, which can output levitation force and torque simultaneously. In order to analyze the character of the force, analytic method and finite element method are adopted to model the motor. To make sure the HTS can carry sufficiently large current and work well, the magnetic field distribution in HTS coil is calculated. An effective method to improve the critical current of HTS coil is presented. Then, AC losses in HTS windings in the motor are estimated and tested
Axial power monitoring uncertainty in the Savannah River Reactors
International Nuclear Information System (INIS)
Losey, D.C.; Revolinski, S.M.
1990-01-01
The results of this analysis quantified the uncertainty associated with monitoring the Axial Power Shape (APS) in the Savannah River Reactors. Thermocouples at each assembly flow exit map the radial power distribution and are the primary means of monitoring power in these reactors. The remaining uncertainty in power monitoring is associated with the relative axial power distribution. The APS is monitored by seven sensors that respond to power on each of nine vertical Axial Power Monitor (APM) rods. Computation of the APS uncertainty, for the reactor power limits analysis, started with a large database of APM rod measurements spanning several years of reactor operation. A computer algorithm was used to randomly select a sample of APSs which were input to a code. This code modeled the thermal-hydraulic performance of a single fuel assembly during a design basis Loss-of Coolant Accident. The assembly power limit at Onset of Significant Voiding was computed for each APS. The output was a distribution of expected assembly power limits that was adjusted to account for the biases caused by instrumentation error and by measuring 7 points rather than a continuous APS. Statistical analysis of the final assembly power limit distribution showed that reducing reactor power by approximately 3% was sufficient to account for APS variation. This data confirmed expectations that the assembly exit thermocouples provide all information needed for monitoring core power. The computational analysis results also quantified the contribution to power limits of the various uncertainties such as instrumentation error
Numerical Analysis of Erosion Caused by Biomimetic Axial Fan Blade
Directory of Open Access Journals (Sweden)
Jun-Qiu Zhang
2013-01-01
Full Text Available Damage caused by erosion has been reported in several industries for a wide range of situations. In the present work, a new method is presented to improve the erosion resistance of machine components by biomimetic method. A numerical investigation of solid particle erosion in the standard and biomimetic configuration blade of axial fan is presented. The analysis consists in the application of the discrete phase model, for modeling the solid particles flow, and the Eulerian conservation equations to the continuous phase. The numerical study employs computational fluid dynamics (CFD software, based on a finite volume method. User-defined function was used to define wear equation. Gas/solid flow axial fan was simulated to calculate the erosion rate of the particles on the fan blades and comparatively analyzed the erosive wear of the smooth surface, the groove-shaped, and convex hull-shaped biomimetic surface axial flow fan blade. The results show that the groove-shaped biomimetic blade antierosion ability is better than that of the other two fan blades. Thoroughly analyze of antierosion mechanism of the biomimetic blade from many factors including the flow velocity contours and flow path lines, impact velocity, impact angle, particle trajectories, and the number of collisions.
Characteristics of tip-leakage flow in an axial fan
Park, Keuntae; Choi, Haecheon; Choi, Seokho; Sa, Yongcheol
2014-11-01
An axial fan with a shroud generates complicated vortical structures by the interaction of the axial flow with the fan blades and shroud near the blade tips. Large eddy simulation (LES) is performed for flow through a forward-swept axial fan, operating at the design condition of Re = 547,000 based on the radius of blade tip and the tip velocity. A dynamic global model (Lee et al. 2010) is used for a subgrid-scale model, and an immersed boundary method in a non-inertial reference frame (Kim & Choi 2006) is adopted for the present simulation. It is found that two vortical structures are formed near the blade tip: the main tip leakage vortex (TLV) and the auxiliary TLV. The main TLV is initiated near the leading edge, develops downstream, and impinges on the pressure surface of the next blade, where the pressure fluctuations and turbulence intensity become high. On the other hand, the auxiliary TLV is initiated at the aft part of the blade but is relatively weak such that it merges with the main TLV. Supported by the KISTI Supercomputing Center (KSC-2014-C2-014).
Hewage, Trishan A.M.; Alderson, Kim L; Alderson, Andrew; Scarpa, Fabrizio
2016-01-01
Intuitively, materials become both shorter and wider when compressed along their length. Here we show how a composite material or structure can display a simultaneous reversal in the direction of deformation for both the axial and transverse dimensions, corresponding to negative values of effective stiffness and effective Poisson’s ratio, respectively. A negative Poisson’s ratio[1] (NPR or auxetic[2]) host assembly stabilising (otherwise unstable) embedded negative stiffness[3] (NS) elements ...
Axial resolution of confocal Raman microscopes : Gaussian beam theory and practice
Grauw, C J De; Sijtsema, N M; Otto, C; Greve, J
1997-01-01
A straightforward and transparent model, based on Gaussian beam optics, for the axial ro resolution of a confocal microscope is presented, A confocal Raman microscope was used to determine the axial confocality in practice. The axial response of a thin planar object was measured for three different
Axial Resolution of Confocal Raman Microscopes: Gaussian Beam Theory and Practice
de Grauw, C.J.; de Grauw, C.J.; Sijtsema, N.M.; Otto, Cornelis; Greve, Jan
1997-01-01
A straightforward and transparent model, based on Gaussian beam optics, for the axial r0 resolution of a confocal microscope is presented. A confocal Raman microscope was used to determine the axial confocality in practice. The axial response of a thin planar object was measured for three different
Moyer, R.D.
A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.
Experimental Study of Axially Tension Cold Formed Steel Channel Members
Apriani, Widya; Lubis, Fadrizal; Angraini, Muthia
2017-12-01
Experimental testing is commonly used as one of the steps to determine the cause of the collapse of a building structure. The collapse of structures can be due to low quality materials. Although material samples have passed laboratory tests and the existing technical specifications have been met but there may be undetected defects and known material after failure. In this paper will be presented Experimental Testing of Axially Tension Cold Formed Steel Channel Members to determine the cause of the collapse of a building roof truss x in Pekanbaru. Test of tensile strength material cold formed channel sections was performed to obtain the main characteristics of Cold Formed steel material, namely ultimate tensile strength loads that can be held by members and the yield stress possessed by channel sections used in construction. Analysis of axially tension cold formed steel channel section presents in this paper was conducted through experimental study based on specificationsAnnualBook of ASTM Standards: Metal Test methods and Analitical Procedures, Section 3 (1991). The result of capacity loads experimental test was compared with design based on SNI 03-7971-2013standard of Indonesia for the design of cold formed steel structural members. The results of the yield stress of the material will be seen against the minimum allowable allowable stress range. After the test, the percentace of ultimate axial tension capacity theory has a result that is 16.46% larger than the ultimate axial tension capacity experimental. When compared with the load that must be borne 5.673 kN/m it can be concluded that 2 specimens do not meet. Yield stress of member has fulfilled requirement that wass bigger than 550 MPa. Based on the curve obtained ultimate axial tension capacity theory, results greater than experimental. The greatest voltage value (fu) is achieved under the same conditions as its yield stress. For this specimen with a melting voltage value fy = 571.5068 MPa has fulfilled the
Design and axial optimization of nuclear fuel for BWR reactors
International Nuclear Information System (INIS)
Garcia V, M.A.
2006-01-01
In the present thesis, the modifications made to the axial optimization system based on Tabu Search (BT) for the axial design of BWR fuel type are presented, developed previously in the Nuclear Engineering Group of the UNAM Engineering Faculty. With the modifications what is mainly looked is to consider the particular characteristics of the mechanical design of the GE12 fuel type, used at the moment in the Laguna Verde Nucleo electric Central (CNLV) and that it considers the fuel bars of partial longitude. The information obtained in this thesis will allow to plan nuclear fuel reloads with the best conditions to operate in a certain cycle guaranteeing a better yield and use in the fuel burnt, additionally people in charge in the reload planning will be favored with the changes carried out to the system for the design and axial optimization of nuclear fuel, which facilitate their handling and it reduces their execution time. This thesis this developed in five chapters that are understood in the following way in general: Chapter 1: It approaches the basic concepts of the nuclear energy, it describes the physical and chemical composition of the atoms as well as that of the uranium isotopes, the handling of the uranium isotope by means of the nuclear fission until arriving to the operation of the nuclear reactors. Chapter 2: The nuclear fuel cycle is described, the methods for its extraction, its conversion and its enrichment to arrive to the stages of the nuclear fuel management used in the reactors are described. Beginning by the radial design, the axial design and the core design of the nuclear reactor related with the fuel assemblies design. Chapter 3: the optimization methods of nuclear fuel previously used are exposed among those that are: the genetic algorithms method, the search methods based on heuristic rules and the application of the tabu search method, which was used for the development of this thesis. Chapter 4: In this part the used methodology to the
Guptha, V. L. Jagannatha; Sharma, Ramesh S.
2017-11-01
The use of FRP composite materials in aerospace, aviation, marine, automotive and civil engineering industry has increased rapidly in recent years due to their high specific strength and stiffness properties. The structural members contrived from such composite materials are generally subjected to complex loading conditions and leads to multi-axial stress conditions at critical surface localities. Presence of notches, much required for joining process of composites, makes it further significant. The current practice of using uni-axial test data alone to validate proposed material models is inadequate leading to evaluation and consideration of bi-axial test data. In order to correlate the bi-axial strengths with the uni-axial strengths of GFRP composite laminates in the presence of a circular notch, bi-axial tests using four servo-hydraulic actuators with four load cells were carried out. To determine the in-plane strength parameters, bi-axial cruciform test specimen model was considered. Three different fibre orientations, namely, 0°, 45°, and 90° are considered with a central circular notch of 10 mm diameter in the present investigation. From the results obtained, it is observed that there is a reduction in strength of 5.36, 2.41 and 13.92% in 0°, 45°, and 90° fibre orientation, respectively, under bi-axial loading condition as compared to that of uni-axial loading in laminated composite.
International Nuclear Information System (INIS)
Al Jubori, Ayad; Daabo, Ahmed; Al-Dadah, Raya K.; Mahmoud, Saad; Ennil, Ali Bahr
2016-01-01
Highlights: • One and three-dimensional analysis with real gas properties are integrated. • Micro axial and radial-inflow turbines configurations are investigated. • Five organic working fluids are considered. • The maximum total isentropic efficiency of radial-inflow turbine 83.85%. • The maximum ORC thermal efficiency based on radial-inflow turbine is 10.60%. - Abstract: Most studies on the organic Rankine cycle (ORC) focused on parametric studies and selection working fluids to maximize the performance of organic Rankine cycle but without attention for turbine design features which are crucial to achieving them. The rotational speed, expansion ratio, mass flow rate and turbine size have markedly effect on turbine performance. For this purpose organic Rankine cycle modeling, mean-line design and three-dimensional computational fluid dynamics analysis were integrated for both micro axial and radial-inflow turbines with five organic fluids (R141b, R1234yf, R245fa, n-butane and n-pentane) for realistic low-temperature heat source <100 °C like solar and geothermal energy. Three-dimensional simulation is performed using ANSYS R17 -CFX where three-dimensional Reynolds-averaged Navier-Stokes equations are solved with k-omega shear stress transport turbulence model. Both configurations of turbines are designed at wide range of mass flow rate (0.1–0.5) kg/s for each working fluid. The results showed that n-pentane has the highest performance at all design conditions where the maximum total-to-total efficiency and power output of radial-inflow turbine are 83.85% and 8.893 kW respectively. The performance of the axial turbine was 83.48% total-to-total efficiency and 8.507 kW power output. The maximum overall size of axial turbine was 64.685 mm compared with 70.97 mm for radial-inflow turbine. R245fa has the lowest overall size for all cases. The organic Rankine cycle thermal efficiency was about 10.60% with radial-inflow turbine and 10.14% with axial turbine
Experimental Study on Ultrahigh Strength Concrete Filled Steel Tube Short Columns under Axial Load
Directory of Open Access Journals (Sweden)
Xiaojun Zhou
2017-01-01
Full Text Available Based on the project of Modaoxi Bridge, an experimental study on the compressive behavior of ultrahigh strength concrete filled steel tube (UHSCFST short column was conducted. A total of 9 UHSCFST specimens were tested, and the cube strength (fcu of the core concrete reached 115.4 MPa. Main parameters were the confining factor (ξ=0.608, 0.919, and 1.015, steel ratio (α=14.67%, 20.02%, and 21.98%, and steel strength (fy = 349 MPa, 352 MPa, and 427 MPa. The axially loading test results showed that the visible damage of steel tube occurred under the ultimate load. The higher the confining effect, the less the damage features. And all specimens basically presented a drum-type failure mode. The confining effect of steel tube effectively changed the brittle failure mode of ultrahigh strength concrete (UHSC and tremendously improved the load bearing capacity and ductility of specimens. Moreover, the higher the steel ratio and steel strength of the specimens, the stronger the confining effect. Meanwhile the excellent mechanical properties will be obtained. Also it is recommended that the UHSCFST prefers Q345 or above strength steel tube to ensure sufficient ductility, and the steel ratio should be more than 20%. Furthermore, the confining effect of steel tubes can improve the ultimate bearing capacity of the ultrahigh strength CFST short columns.
Axial charge of the weak nucleon current extracted from the β decays of spin aligned 12B and 12N
International Nuclear Information System (INIS)
Yamaguchi, Takayuki
1998-01-01
The alignment correlation terms in the β-ray angular distributions of the 12 B and 12 N mirror nuclei have been precisely measured, in order to investigate the mesonic effect in the axial charge matrix element. The spin alignments were created with the spin manipulation technique in the β-NMR method, which has been improved based on the recent studies of hyperfine interactions of 12 B and 12 N in a Mg crystal. From the sum of the alignment correlation terms, the ratio of the axial charge to the Gamow-Teller term was determined to be y = 4.66 ± 0.06(stat) ± 0.13(syst). The present result gives clear evidence of the mesonic effect in the axial charge and even more shows 16 ± 6% enhancement over the full calculation which includes the meson exchange effect and the core polarization effect. A possible mass renormalization for the decaying nucleon in a finite nucleon density explains this enhancement. (author)
Energy Technology Data Exchange (ETDEWEB)
Garcia V, M.A
2006-07-01
In the present thesis, the modifications made to the axial optimization system based on Tabu Search (BT) for the axial design of BWR fuel type are presented, developed previously in the Nuclear Engineering Group of the UNAM Engineering Faculty. With the modifications what is mainly looked is to consider the particular characteristics of the mechanical design of the GE12 fuel type, used at the moment in the Laguna Verde Nucleo electric Central (CNLV) and that it considers the fuel bars of partial longitude. The information obtained in this thesis will allow to plan nuclear fuel reloads with the best conditions to operate in a certain cycle guaranteeing a better yield and use in the fuel burnt, additionally people in charge in the reload planning will be favored with the changes carried out to the system for the design and axial optimization of nuclear fuel, which facilitate their handling and it reduces their execution time. This thesis this developed in five chapters that are understood in the following way in general: Chapter 1: It approaches the basic concepts of the nuclear energy, it describes the physical and chemical composition of the atoms as well as that of the uranium isotopes, the handling of the uranium isotope by means of the nuclear fission until arriving to the operation of the nuclear reactors. Chapter 2: The nuclear fuel cycle is described, the methods for its extraction, its conversion and its enrichment to arrive to the stages of the nuclear fuel management used in the reactors are described. Beginning by the radial design, the axial design and the core design of the nuclear reactor related with the fuel assemblies design. Chapter 3: the optimization methods of nuclear fuel previously used are exposed among those that are: the genetic algorithms method, the search methods based on heuristic rules and the application of the tabu search method, which was used for the development of this thesis. Chapter 4: In this part the used methodology to the
Zhang, Peng; Le, Son T.; Hou, Xiaoxiao; Zaslavsky, A.; Perea, Daniel E.; Dayeh, Shadi A.; Picraux, S. T.
2014-08-01
We report on room-temperature negative transconductance (NTC) in axial Si/Ge hetero-nanowire tunneling field-effect transistors. The NTC produces a current peak-to-valley ratio >45, a high value for a Si-based device. We characterize the NTC over a range of gate VG and drain VD voltages, finding that NTC persists down to VD = -50 mV. The physical mechanism responsible for the NTC is the VG-induced depletion in the p-Ge section that eventually reduces the maximum electric field that triggers the tunneling ID, as confirmed via three-dimensional (3D) technology computer-aided design simulations.
International Nuclear Information System (INIS)
Hooper, J.D.
1977-01-01
A combined experimental and numerical model of a turbulent single phase coolant, flowing axially along the fuel pins of a nuclear reactor, was developed. The experimental rig represented two interconnected subchannels of a square array at a pitch/diameter ratio of 1.193. Air was the working fluid, and measurements were made of the mean radial velocity profiles, wall shear stress variation, turbulence velocity spectra and intensities. The numerically predicted wall shear distribution and mean velocity profiles, obtained using an empirical two-dimensional mixing length and eddy diffusivity concept to represent fluid turbulence, showed good agreement with the experimental results. (Author)
International Nuclear Information System (INIS)
Amano, Osamu
2007-01-01
We need more oil energy to take out oil under the ground. Limit resources make us consider other candidates of energy source instead of oil. Electricity shall be the main role more and more like electric vehicles and air conditioners so we should consider electricity generation ways. When we consider what kind of electric power generation is the best or suitable, we should not only power generation plant but whole process from mining to power generation. It is good way to use EPR, Energy Profit Ratio, to analysis which type is more efficient and which part is to do research and development when you see the input breakdown analysis. Electricity by the light water nuclear power plant, the hydrogen power plant and the geothermal power plant are better candidates from EPR analysis. Forecasting the world primly energy supply in 2050, it is said that the demand will be double of the demand in 2000 and the supply will not be able to satisfy the demand in 2050. We should save 30% of the demand and increase nuclear power plants 3.5 times more and recyclable energy like hydropower plants 3 times more. When the nuclear power plants are 3.5 times more then uranium peak will come and we will need breed uranium. I will analysis the EPR of FBR. Conclusion: A) the EPR of NPS in Japan is 17.4 and it is the best of all. B) Many countries will introduce new nuclear power plants rapidly may be 3.5 times in 2050. C) Uranium peak will happen around 2050. (author)
Axial dispersion via shear-enhanced diffusion in colloidal suspensions
Griffiths, I. M.
2012-03-01
The familiar example of Taylor dispersion of molecular solutes is extended to describe colloidal suspensions, where the fluctuations that contribute to dispersion arise from hydrodynamic interactions. The generic scheme is illustrated for a suspension of particles in a pressure-driven pipe flow, with a concentration-dependent diffusivity that captures both the shear-induced and Brownian contributions. The effect of the cross-stream migration via shear-induced diffusion is shown to dramatically reduce the axial dispersion predicted by classical Taylor dispersion for a molecular solute. Analytic and numerical solutions are presented that illustrate the effect of the concentration dependence of this nonlinear hydrodynamic mechanism. Copyright © EPLA, 2012.
Axial gas flow in irradiated PWR fuel rods
International Nuclear Information System (INIS)
Dagbjartsson, S.J.; Murdock, B.A.; Owen, D.E.; MacDonald, P.E.
1977-09-01
Transient and steady state axial gas flow experiments were performed on six irradiated, commercial pressurized water reactor fuel rods at ambient temperature and 533 K. Laminar flow equations, as used in the FRAP-T2 and SSYST fuel behavior codes, were used with the gas flow results to calculate effective fuel rod radial gaps. The results of these analyses were compared with measured gap sizes obtained from metallographic examination of one fuel rod. Using measured gap sizes as input, the SSYST code was used to calculate pressure drops and mass fluxes and the results were compared with the experimental gas flow data
Test Procedure for Axially Loaded Piles in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina
The test procedure described in the following is used when examining the effects of static or cyclic loading on the skin friction of an axially loaded pile in dense sand. The pile specimen is only loaded in tension to avoid any contribution from the base resistance. The pile dimensions are chosen...... to resemble full scale dimension of piles used in offshore pile foundations today. In this report is given a detailed description of the soil preparation and pile installation procedures as well data acquisition methods....
Renormalisation group flows for gauge theories in axial gauges
Litim, Daniel F; Litim, Daniel F.; Pawlowski, Jan M.
2002-01-01
Gauge theories in axial gauges are studied using Exact Renormalisation Group flows. We introduce a background field in the infrared regulator, but not in the gauge fixing, in contrast to the usual background field gauge. It is shown how heat-kernel methods can be used to obtain approximate solutions to the flow and the corresponding Ward identities. Expansion schemes are discussed, which are not applicable in covariant gauges. As an application, we derive the one-loop effective action for covariantly constant field strength, and the one-loop beta-function for arbitrary regulator.
Axial and Radial Gas Holdup in Bubble Column Reactor
International Nuclear Information System (INIS)
Wagh, Sameer M.; Ansari, Mohashin E Alan; Kene, Pragati T.
2014-01-01
Bubble column reactors are considered the reactor of choice for numerous applications including oxidation, hydrogenation, waste water treatment, and Fischer-Tropsch (FT) synthesis. They are widely used in a variety of industrial applications for carrying out gas-liquid and gas-liquid-solid reactions. In this paper, the computational fluid dynamics (CFD) model is used for predicting the gas holdup and its distribution along radial and axial direction are presented. Gas holdup increases linearly with increase in gas velocity. Gas bubbles tends to concentrate more towards the center of the column and follows a wavy path
Time Dependent and Steady Uni-axial Elongational Viscosity
DEFF Research Database (Denmark)
Nielsen, Jens K.; Rasmussen, Henrik Koblitz; Hassager, Ole
2005-01-01
Here we present measurements of transient and steady uni-axial elongational viscosity, using the Filament Stretching Rheometer1 or FSR1 (see Fig. 1) of the following melts: Four narrow MMD polystyrene (PS) samples with weight-average molar mass Mw in the range of 50k to 390k. Three different bi......-disperse samples, mixed from the narrow MMD PS. Two low-density polyethylene (LDPE) melts (Lupolen 1840D and 3020D). A steady-state viscosity was kept for 1-2.5 Hencky strain units in all measurements....
Plasticity around an Axial Surface Crack in a Cylindrical Shell
DEFF Research Database (Denmark)
Krenk, Steen
1979-01-01
field in an axially cracked cylindrical shell arising from use of classical eighth order shallow shell theory is removed when use is made of a tenth order shell theory which accounts for transverse shear deformations. Although the membrane stresses are only moderately affected, the influence...... and Ratwani,3–5 it generalises Dugdale's assumption of a concentrated yield zone in the plane of the crack but, contrary to that model, transverse shear effects are included and a continuous stress distribution is assumed in the yield zone. The inherent difficulties arising from the use of shell theory...
Axial gravitational waves in FLRW cosmology and memory effects
Kulczycki, Wojciech; Malec, Edward
2017-09-01
We show initial data for gravitational axial waves that are twice differentiable but that are not C2. They generate wave pulses that interact with matter in the radiation cosmological era. This forces the radiation matter to rotate. This rotation is permanent—it persists after the passage of the gravitational pulse. The observed inhomogeneities of the cosmic microwave background radiation put a bound onto discontinuities of superhorizon metric perturbations. We explicitly show that a class of smooth initial metrics that are at least C2 gives rise to gravitational wave pulses that do not interact with the background during the radiation epoch.
Static Tension Tests on Axially Loaded Pile Segments in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo
This paper provides laboratory test results of static axially loaded piles in sand. With a newly developed test setup, the pile-soil interface friction was investigated by using an open-ended steel pile segment with a diameter of 0.5 m. Use of a pile length of 1 m enabled the pile-soil interface...... friction to be analyzed at a given soil horizon while increasing the vertical effective stress in the sand. Test results obtained by this approach can be analyzed as single t-z curves and compared to predictions of unit shaft friction from current design methods for offshore foundations. The test results...
Parametric design of tri-axial nested Helmholtz coils.
Abbott, Jake J
2015-05-01
This paper provides an optimal parametric design for tri-axial nested Helmholtz coils, which are used to generate a uniform magnetic field with controllable magnitude and direction. Circular and square coils, both with square cross section, are considered. Practical considerations such as wire selection, wire-wrapping efficiency, wire bending radius, choice of power supply, and inductance and time response are included. Using the equations provided, a designer can quickly create an optimal set of custom coils to generate a specified field magnitude in the uniform-field region while maintaining specified accessibility to the central workspace. An example case study is included.
Nonlinear vibration of an axially loaded beam carrying rigid bodies
Directory of Open Access Journals (Sweden)
O. Barry
2016-12-01
Full Text Available This paper investigates the nonlinear vibration due to mid-plane stretching of an axially loaded simply supported beam carrying multiple rigid masses. Explicit expressions and closed form solutions of both linear and nonlinear analysis of the present vibration problem are presented for the first time. The validity of the analytical model is demonstrated using finite element analysis and via comparison with the result in the literature. Parametric studies are conducted to examine how the nonlinear frequency and frequency response curve are affected by tension, rotational inertia, and number of intermediate rigid bodies.
Directory of Open Access Journals (Sweden)
Chengde Tong
2017-05-01
Full Text Available The axial-flux magnetic-field-modulated brushless double-rotor machine (MFM-BDRM is a possible alternative as a power-split device for hybrid electric vehicles (HEVs. However, the existence of large axial force may lead to assembly problems and rich inner air-gap harmonics could result in high PM loss and low efficiency. This paper proposes a novel axial-flux MFM-BDRM with improved PM rotor structure. 2-D analytical method to predict the magnetic-field distribution of the proposed MFM-BDRM is developed and the design procedure of the proposed machine is illustrated. The impact of key geometrical parameters on axial force and torque is investigated. To evaluate the advantage of the proposed machine, a comparison is made with a conventional one with respect to electromagnetic performances. Results show that the proposed machine is effective in reducing PM eddy loss and axial force by 60% and 35%, respectively.
Blachier, Martin; Canouï-Poitrine, Florence; Dougados, Maxime; Lethuaut, Aurélie; Fautrel, Bruno; Ferkal, Salah; Le Corvoisier, Philippe; Farrenq, Valérie; Poulain, Cécile; Ghaleh, Bijan; Bastuji-Garin, Sylvie; Claudepierre, Pascal
2013-09-01
To assess whether factors such as inflammation by laboratory tests and MRI differ between early axial SpA with and without radiographic lesions. Cross-sectional analysis of baseline data from Devenir des Spondylarthropathies Indifferenciées Récentes (DESIR) cohort patients having recent-onset inflammatory back pain and meeting Assessment of SpondyloArthritis international Society criteria. The baseline evaluation included radiographs and MRI of the SI joints (SIJs) and spine. Patients were classified as having radiographic lesions if they had at least one obvious sacroiliitis, grade 2 for at least one vertebral corner or grade 1 for at least two vertebral corners (at the cervical or lumbar level, according to the modified Stoke Ankylosing Spondylitis Spine Score). Associations between baseline characteristics and the presence of radiographic lesions were evaluated by estimating multi-adjusted odd ratios (aORs) and their 95% CIs using a logistic regression model. Of 475 patients, 180 (37.9%) had radiographic lesions. Factors positively associated with radiographic lesions were alcohol use (aOR 2.42; 95% CI 1.31, 4.44; P = 0.005), CRP level (aOR 1.44; 95% CI 1.13, 1.84; P = 0.003) and SIJ inflammation by MRI (aOR 2.25; 95% CI 1.40, 3.60; P = 0.001); negative associations occurred with good NSAID responsiveness (aOR 0.44; 95% CI 0.24, 0.81; P = 0.008); spinal MRI inflammation was associated with radiographic lesions only in smokers (aOR 1.99; 95% CI 1.01, 3.92; P = 0.048). Alcohol use, poor responsiveness to NSAIDs, CRP elevation, SIJ MRI inflammation and spinal MRI inflammation in smokers were independently associated with radiographic lesions in early axial SpA.
Competition between modes with different axial structures in gyrotrons
International Nuclear Information System (INIS)
Khutoryan, Eduard M.; Nusinovich, Gregory S.; Sinitsyn, Oleksandr V.
2014-01-01
This study was motivated by some experiments in which it was found that during the voltage rise, instead of expected excitation of a high-frequency parasitic mode, the excitation of a lower-frequency parasitic mode takes place in a certain range of voltages. For explaining this fact, the dependence of start currents of possible competing modes on the beam voltage was carried out in the cold-cavity approximation and by using the self-consistent approach. It was found that in the case of cavities, which consist of the combination of a section of constant radius waveguide and a slightly uptapered waveguide, these two approaches yield completely different results. Thus, experimentally observed excitation of the low-frequency parasitic mode can be explained by the self-consistent modification of the axial profile of the excited field, which has strong influence on the diffractive quality factor of competing modes. This modification is especially pronounced in the case of excitation of modes with many axial variations which can be excited in the region of beam interaction with the backward-wave component of such modes
Spine labeling in axial magnetic resonance imaging via integral kernels.
Miles, Brandon; Ben Ayed, Ismail; Hojjat, Seyed-Parsa; Wang, Michael H; Li, Shuo; Fenster, Aaron; Garvin, Gregory J
2016-12-01
This study investigates a fast integral-kernel algorithm for classifying (labeling) the vertebra and disc structures in axial magnetic resonance images (MRI). The method is based on a hierarchy of feature levels, where pixel classifications via non-linear probability product kernels (PPKs) are followed by classifications of 2D slices, individual 3D structures and groups of 3D structures. The algorithm further embeds geometric priors based on anatomical measurements of the spine. Our classifier requires evaluations of computationally expensive integrals at each pixel, and direct evaluations of such integrals would be prohibitively time consuming. We propose an efficient computation of kernel density estimates and PPK evaluations for large images and arbitrary local window sizes via integral kernels. Our method requires a single user click for a whole 3D MRI volume, runs nearly in real-time, and does not require an intensive external training. Comprehensive evaluations over T1-weighted axial lumbar spine data sets from 32 patients demonstrate a competitive structure classification accuracy of 99%, along with a 2D slice classification accuracy of 88%. To the best of our knowledge, such a structure classification accuracy has not been reached by the existing spine labeling algorithms. Furthermore, we believe our work is the first to use integral kernels in the context of medical images. Copyright Â© 2016 Elsevier Ltd. All rights reserved.
Axial length of atomic bomb survivors in Nagasaki
International Nuclear Information System (INIS)
Wakiyama, Harumi; Kishikawa, Yasuhiro; Imamura, Naoki; Amemiya, Tsugio
2002-01-01
We reviewed a series of 778 patients who had cataract surgery during the past 4 years at the Nagasaki Atomic Bomb Memorial Hospital. We evaluated the history of exposure to radiation by atomic bomb in 1945, axial length and state of refraction. All were born before 1945. The series comprised 263 males and 515 females. Their ages averaged 76.5±8.6 years. History of exposure to radiation was present in 356 patients. The remaining 422 patients served as control. There was no difference in the type of cataract between the two groups. High myopia was present in 11 irradiated patients (3.2%) and in 24 patients in the control group (6.0%). The difference was not significant (p=0.083). There was no high myopia among 24 patients who were aged 18 years or less at the time of radiation and who were within 2 km from the epicenter. No difference was present regarding the axial length between the two groups or between both sexes. The present result is not definitive because ''irradiated group'' would include those with little or no exposure and because precise data has not been available about the dosis of radiation. (author)
Axial anomaly and index theorem for Dirac-Kaehler fermions
International Nuclear Information System (INIS)
Fonseca Junior, C.A.L. da.
1985-02-01
Some aspects of topological influence on gauge field theory are analysed, considering the geometry and differential topology methods. A review of concepts of differential forms, fibered spaces, connection and curvature, showing an interpretation of gauge theory in this context, is presented. The question of fermions, analysing in details the Dirac-Kaehler which fermionic particle is considered a general differential form, is studied. It is shown how the explicit expressions in function of the Dirac spinor components vary with the Dirac matrix representation. The Dirac-Kahler equation contains 4 times (in 4 dimensions) the Dirac equation, each particle being associated an ideal at left of the algebra of general differential forms. These ideals and the SU(4) symmetry among them are also studied on the point of view of spinors and, the group of reduction to one of the ideals is identified as the Cartan subalgebra of this SU(4). Finally, the axial anomaly is calculated through the functional determinant given by the Dirac-Kaehler operator. The regularization method is the Seeley's coefficients. From that results a comparison of the index theorems for the twisted complexes of signature and spin, which proportionality is given by the number of the algebra ideals contained in the Dirac-Kaehler equation and which also manifests in the respective axial anomaly equations. (L.C.) [pt
Axial U(1) current in Grabowska and Kaplan's formulation
Hamada, Yu; Kawai, Hikaru
2017-06-01
Recently, Grabowska and Kaplan [Phys. Rev. Lett. 116, 211602 (2016); Phys. Rev. D 94, 114504 (2016)] suggested a nonperturbative formulation of a chiral gauge theory, which consists of the conventional domain-wall fermion and a gauge field that evolves by gradient flow from one domain wall to the other. We introduce two sets of domain-wall fermions belonging to complex conjugate representations so that the effective theory is a 4D vector-like gauge theory. Then, as a natural definition of the axial-vector current, we consider a current that generates simultaneous phase transformations for the massless modes in 4 dimensions. However, this current is exactly conserved and does not reproduce the correct anomaly. In order to investigate this point precisely, we consider the mechanism of the conservation. We find that this current includes not only the axial current on the domain wall but also a contribution from the bulk, which is nonlocal in the sense of 4D fields. Therefore, the local current is obtained by subtracting the bulk contribution from it.
Nanowelding configuration between carbon nanotubes in axial direction
International Nuclear Information System (INIS)
Cui Jianlei; Yang Lijun; Wang Yang
2013-01-01
Highlights: ► Nanowelding process could be accomplished at a lower temperature than the melting point of the bulk solder. ► CNTs are connected with solder joints of nodule shape. ► Some silver atoms are captured and dragged into carbon nanotube to form the core filling structures of nanowires. ► Some silver atoms diffuse along the outer walls of SWNTs with the dominant mechanism of capillary wetting. - Abstract: Interconnect technology of carbon nanotubes (CNTs) is essential for functional devices. However, difficulty in the fabrication of the interface between carbon nanotube (CNT) and CNT in axial direction, hindered the quality of connection and practical applications of electrical devices. Also, investigation of dynamic evolution of connection configuration about nanowelding is still lacking. In order to analyze the nanowelding configuration between CNTs in axial direction, the different connection cases are investigated using molecular dynamics simulation. Simulation results show that the nanowelding process could be accomplished at a lower temperature than the melting point of the bulk solder and the CNTs are connected with solder joints of nodule shape. It is also found that metal atoms are captured and dragged into nanotube to form the core filling structures of nanowires during nanowelding. Also, the connection configuration shows that Ag atoms diffuse along the outer walls of SWNTs with the dominant mechanism of capillary wetting, which would increase the contact length to improve the mechanical strength.
Factors influencing surgical complications of intra-axial brain tumours.
Brell, M; Ibáñez, J; Caral, L; Ferrer, E
2000-01-01
Extensive surgical resection remains nowadays the best treatment available for most intra-axial brain tumours. However, postoperative sequelae can outweigh the potential benefits of surgery. The goal of this study has been to review the results of this treatment in our Department in order to quantify morbidity and mortality and determine predictive risk factors for each patient. We report a retrospective study of 200 patients submitted to a craniotomy for intra-axial brain tumours including gliomas and metastases. Postoperative major complications are analysed and related to different variables. An exhaustive review of the literature concerning the main controversial points about primary and metastatic brain tumours surgery is done. The overall major complication rate was 27.5%, with neurological complications being the most frequently encountered. We did not find a statistically significant relation between them and the grade of eloquence of the tumoural area. Infratentorial tumour location, previous radiotherapy and reoperations were factors strongly related to the incidence of regional complications. Age over 60 and severe concomitant disease were risk factors for systemic complications. The results from published series concerning surgical complications after craniotomies for brain tumours are not comparable because of the lack of homogeneity between them. The knowledge of the complications rate in each particular neurosurgical department turns out essentially to provide the patient with tailored information about risks before surgery.
Lee, Sang-Mok; Choi, Hyuk Jin; Choi, Heejin; Kim, Mee Kum; Wee, Won Ryang
2016-10-07
BACKGROUND: Though the development and fitting of scleral contact lenses are expanding steadily, there is no simple method to provide scleral metrics for scleral contact lens fitting yet. The aim of this study was to establish formulae for estimation of the axial radius of curvature (ARC) of the anterior sclera using ocular biometric parameters that can be easily obtained with conventional devices. A semi-automated stitching method and a computational analysis tool for calculating ARC were developed by using the ImageJ and MATLAB software. The ARC of all the ocular surface points were analyzed from the composite horizontal cross-sectional images of the right eyes of 24 volunteers; these measurements were obtained using anterior segment optical coherence tomography for a previous study (AS-OCT; Visante). Ocular biometric parameters were obtained from the same volunteers with slit-scanning topography and partial coherence interferometry. Correlation analysis was performed between the ARC at 8 mm to the axis line (ARC[8]) and other ocular parameters (including age). With ARC obtained on several nasal and temporal points (7.0, 7.5, 8.0, 8.5, and 9.0 mm from the axis line), univariate and multivariate linear regression analyses were performed to develop a model for estimating ARC with the help of ocular biometric parameters. Axial length, spherical equivalent, and angle kappa showed correlations with temporal ARC[8] (tARC[8]; Pearson's r = 0.653, -0.579, and -0.341; P = 0.001, 0.015, and 0.015, respectively). White-to-white corneal diameter (WTW) and anterior chamber depth (ACD) showed correlation with nasal ARC[8] (nARC[8]; Pearson's r = -0.492 and -0.461; P = 0.015 and 0.023, respectively). The formulae for estimating scleral curvatures (tARC, nARC, and average ARC) were developed as a function of axial length, ACD, WTW, and distance from the axis line, with good determinant power (72 - 80 %; SPSS ver. 22.0). Angle kappa showed strong
The effects of initial rise and axial loads on MEMS arches
Tella, Sherif Adekunle
2017-04-07
Arch microbeams have been utilized and proposed for many uses over the past few years due to their large tunability and bistability. However, recent experimental data have shown different mechanical behavior of arches when subjected to axial loads. This paper aims to investigate in depth the influence of the competing effects of initial rise and axial loads on the mechanical behavior of micromachined arches; mainly their static deflection and resonant frequencies. Based on analytical solutions, the static response and eigenvalue problems are analyzed for various values of initial rises and axial loads. Universal curves showing the variation of the first three resonance frequencies of the arch are generated for various values of initial rise under both tensile and compressive axial loads. This study shows that increasing the tensile or compressive axial loads for different values of initial rise may lead to either increase in the stiffness of the beam or initial decrease in the stiffness, which later increases as the axial load is increased depending on the dominant effect of the initial rise of the arch and the axial load. The obtained universal curves represent useful design tools to predict the tunability of arches under axial loads for various values of initial rises. The use of the universal curves is demonstrated with an experimental case study. Analytical formulation is developed to predict the point of minimum where the trend of the resonance frequency versus axial loads changes qualitatively due to the competing effects of axial loads and initial curvature.
Directory of Open Access Journals (Sweden)
Kurt H Schütte
Full Text Available Small wireless trunk accelerometers have become a popular approach to unobtrusively quantify human locomotion and provide insights into both gait rehabilitation and sports performance. However, limited evidence exists as to which trunk accelerometry measures are suitable for the purpose of detecting movement compensations while running, and specifically in response to fatigue. The aim of this study was therefore to detect deviations in the dynamic center of mass (CoM motion due to running-induced fatigue using tri-axial trunk accelerometry. Twenty runners aged 18-25 years completed an indoor treadmill running protocol to volitional exhaustion at speeds equivalent to their 3.2 km time trial performance. The following dependent measures were extracted from tri-axial trunk accelerations of 20 running steps before and after the treadmill fatigue protocol: the tri-axial ratio of acceleration root mean square (RMS to the resultant vector RMS, step and stride regularity (autocorrelation procedure, and sample entropy. Running-induced fatigue increased mediolateral and anteroposterior ratios of acceleration RMS (p < .05, decreased the anteroposterior step regularity (p < .05, and increased the anteroposterior sample entropy (p < .05 of trunk accelerometry patterns. Our findings indicate that treadmill running-induced fatigue might reveal itself in a greater contribution of variability in horizontal plane trunk accelerations, with anteroposterior trunk accelerations that are less regular from step-to-step and are less predictable. It appears that trunk accelerometry parameters can be used to detect deviations in dynamic CoM motion induced by treadmill running fatigue, yet it is unknown how robust or generalizable these parameters are to outdoor running environments.
Directory of Open Access Journals (Sweden)
Song Bing
2016-01-01
Full Text Available Taking the mixing amount of diatomite calcined and vitrified micro bubbles(VMB as the main changing parameters, experiment studies the properties of the vitrified micro bubbles recycled concrete blocks; then this paper adopts the finite element software ANSYS to analyze the square double skin steel stub short columns filled with recycled concrete under axial compression. According to the vertical stress distribution, strain and bearing capacity of the steel tube and core concrete, we make a contrastive axial compression properties analysis on the different hollow ratio χ(0,0.35and the VMB content(0%,100%,130% of square double skin steel stub short columns filled with recycled concrete. The result shows that: Compressive strength of VMB recycled concrete increases with the increase of diatomite calcined content, when mixing amount of diatomite calcined is 3%,the compressive strength of 130% VMB content test specimen can reach 32.45 MPa;Because of the inner circular steel tube is setted which strengthening component buckling capacity and improving the ductility of the component, stress distribution of hollow components is more balance than solid components, and their axial displacements decrease by 5.6% compared with the solid components when they reach ultimate bearing capacity; When the hollow ratio is same, ultimate bearing capacity of 130% VMB content test specimen compared with the content is 0% only reduces by about 3.5%; When the VMB content is same, ultimate bearing capacity of hollow components compared with solid components increases by about 2.5%, which reducing weight as well as improving the anti-seismic performance.
Diffusion air effects on the soot axial distribution concentration in a premixed acetylene/air flame
Energy Technology Data Exchange (ETDEWEB)
Fassani, Fabio Luis; Santos, Alex Alisson Bandeira; Goldstein Junior, Leonardo [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia Termica e de Fluidos]. E-mails: fassani@fem.unicamp.br; absantos@fem.unicamp.br; leonardo@fem.unicamp.br; Ferrari, Carlos Alberto [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica. Dept. de Eletronica Quantica]. E-mail: ferrari@ifi.unicamp.br
2000-07-01
Soot particles are produced during the high temperature pyrolysis or combustion of hydrocarbons. The emission of soot from a combustor, or from a flame, is determined by the competition between soot formation and its oxidation. Several factors affect these processes, including the type of fuel, the air-to-fuel ratio, flame temperature, pressure, and flow pattern. In this paper, the influence of the induced air diffusion on the soot axial distribution concentration in a premixed acetylene/air flame was studied. The flame was generated in a vertical axis burner in which the fuel - oxidant mixture flow was surrounded by a nitrogen discharge coming from the annular region between the burner tube and an external concentric tube. The nitrogen flow provided a shield that protected the flame from the diffusion of external air, enabling its control. The burner was mounted on a step-motor driven, vertical translation table. The use of several air-to-fuel ratios made possible to establish the sooting characteristics of this flame, by measuring soot concentration along the flame height with a non-intrusive laser light absorption technique. (author)
International Nuclear Information System (INIS)
Jung, Byung Ryul; Park, Hu Shin; Chung, Duk Muk; Baik, Se Jin
2000-01-01
The effects of feedwater flow fraction introduced into the downcomer region have been evaluated in terms of steam generator performance based on the same steam generator thermal output for the Korea Standard Nuclear Power Plant (KSNP) steam generator. The KSNP steam generator design has an integral axial flow economizer which is designed such that most of the feedwater is introduced through the economizer region and only a portion of feedwater through the downcomer region. The feedwater flow introduced into the downcomer region is not normally controlled during the power operation. However, the actual feedwater fraction into the downcomer region may differ from the design flow depending on the as-built system and component characteristics. Investigated in this paper were the downcomer feedwater flow effects on the steam pressure, circulation ratio, internal void fraction and velocity distribution in the tube bundle region at the steady state operation using SAFE and ATHOS3 codes. The results show that the steam pressure increases and the resultant total feedwater flow increases with reducing the downcomer feedwater flow fraction for the same steam generator thermal output. The slight off-design condition of downcomer feedwater flow fraction renders no significant effect on the steam generator performance such as circulation ratios, steam qualities, void fractions and internal velocity distributions. The evaluation shows that the slight off-design downcomer feedwater flow fraction deviation up to ± 5% is acceptable for the steam generator performance
Directory of Open Access Journals (Sweden)
Tegegn Dejene Toge
2015-01-01
Full Text Available The present paper is an attempt in understanding the stall inception mechanism in a low speed, contra rotating axial flow fan stage, using wavelet transforms. The rotors used in this study have relatively large tip gap (about 3% of the blade span and aspect ratio of 3. The study was carried out near stall and at stall mass flow conditions for different speed ratios of rotor-2 to rotor-1. Unsteady pressure data from the casing wall mounted sensors are used to understand the stall inception mechanism. The wavelet transform clearly indicates that stall inception occurs mainly through long length scale disturbances for both rotors. It also reveals that short length disturbances occur simultaneously or intermittently in the case of rotor-1. The analysis shows the presence of a strong modal disturbance with 25–80% of the rotor frequency in the case of rotor-1 at the stall mass flow for all the speed combinations studied. The most interesting thing observed in the present study is that the frequency amplitude of the disturbance level is very small for both rotors.
The effects of axial length on the fracture and fragmentation of expanding rings
Directory of Open Access Journals (Sweden)
Razorenov S.V.
2012-08-01
Full Text Available Rings of Ti-6Al-4V with aspect ratios (wall thickness:axial length of 1 : 1, 1 : 2 and 1 : 4 have been expanded to failure at radial strain rates εr ∼ 1 × 104 s−1 using 4340 (EN24T steel and Cu-ETP cylindrical drivers containing a column of RDX. Expansion velocity was measured using VISAR enabling calculation of the stress-strain history of the ring alongside fragment recovery with up to 98% original ring mass recovered. Using the recovered samples average fragment length and mass and final strain have been measured along with analysis of the fracture sites to determine the active failure mechanisms. Perfect rings (aspect ratio 1 : 1 were found to undergo necking before failure, whereas the longer rings failed though ductile tensile cracking at 45∘ to the radius. This data is then compared with finite element analysis results.
Yeh, S. I.; Huang, Y. C.; Cheng, C. H.; Cheng, C. M.; Yang, J. T.
2016-07-01
In this study, we investigated a fluidic system that adheres to new concepts of energy production. To improve efficiency, cost, and ease of manufacture, a millimetrically scaled device that employs a droplet-based co-axial fluidic system was devised to complete alkali-catalyzed transesterification for biodiesel production. The large surface-to-volume ratio of the droplet-based system, and the internal circulation induced inside the moving droplets, significantly enhanced the reaction rate of immiscible liquids used here - soybean oil and methanol. This device also decreased the molar ratio between methanol and oil to near the stoichiometric coefficients of a balanced chemical equation, which enhanced the total biodiesel volume produced, and decreased the costs of purification and recovery of excess methanol. In this work, the droplet-based co-axial fluidic system performed better than other methods of continuous-flow production. We achieved an efficiency that is much greater than that of reported systems. This study demonstrated the high potential of droplet-based fluidic chips for energy production. The small energy consumption and low cost of the highly purified biodiesel transesterification system described conforms to the requirements of distributed energy (inexpensive production on a moderate scale) in the world.
Directory of Open Access Journals (Sweden)
T. Ye. Tsybulskaya
2016-08-01
Full Text Available Aim – to study the relationship of biometric and biomechanical indicators of corneoscleral capsule of the eye in children with axial and refractive mild myopia. Materials and methods. Axial myopia was diagnosed in 32 children (64 eyes, refractive myopia – 18 (36 eyes. The control group – 16 children without ophthalmic diseases (32 eyes. Eye examination: visometry, automated refractometry, biomicroscopy, ophthalmoscopy, determination of the axial length of the eyeball and corneal hysteresis. Results. Significant differences were determined in the indicators of dioptric power of the cornea: 42.2 dpt in patients with axial and 44.7 dpt with refractive myopia (p<0.05, and also difference between patients with refractive myopia and the control group, in which the diopter power of cornea was 42.6 (p<0.05. There are also significant differences in the indicators of the axial length of eyes between axial and refractive myopia – 24.5±0.64 mm and 23.1±0.43 mm (p<0.05. Significant difference with the control group in the axial length marked only in eyes with axial myopia 22.7±0.33 mm and 24.5±0.64 mm, respectively (p<0.05. Corneal hysteresis determined significantly reduced on eyes with both the axial and refractive myopia, which was significantly lower than in the indicators of emmetropic eyes of the control group 13.7 (p<0.05. Corneal hysteresis is inversely related to the axial length of the eyeball: in patients with axial myopia r -0.32, p<0.05; with refractive myopia r -0.36, p<0.05. Сorrelation between diopter power of cornea and axial length of the eyeball: r -0.53, р<0.05 in eyes with axial myopia and r -0.42, p<0.05 refractive myopia. Comparative analysis showed no significant differences between the corneal hysteresis, the axial length of the eye and the spherical component of myopia. Conclusions. In patients with axial and refractive mild myopia corneal hysteresis is reduced on average in 1.2 and 1.1 times, in comparison with
Energy Technology Data Exchange (ETDEWEB)
Fradin, C.
1998-07-01
The prediction of flow structure and performances of an axial transonic compressor requires accurate solvers. Taking into account the complex flow patterns, it is important to validate codes by comparing it with experimental results. It is well understood that the availability of experimental data is fundamentally important for the improvement of the solvers. An axial transonic compressor has been fitted in the ERECA test facility of ONERA. The rotor of this compressor is isolated from stators. This experimental configuration allows to obtain a steady flow into the relative frame linked to the rotor. Due to this fact, experimental tests became easier because the basic phenomena are not hidden by mutual interactions rotor-stator. Measurements have been made in a test section far upstream the rotor, to provide the inlet conditions in the computation domain. Non intrusive and fast response measurement techniques allow to obtain the detailed flow structure in several test sections located in the rotor and far downstream it. All tests were carried out at four operating conditions of the compressor. Results provide good test cases for numerical prediction methods using three-dimensional Navier-Stokes solvers. (author)
Barber, Tim Daniel (Inventor); Hindle, Timothy (Inventor); Young, Ken (Inventor); Davis, Torey (Inventor)
2014-01-01
Embodiments of a launch lock assembly are provided, as are embodiments of a spacecraft isolation system including one or more launch lock assemblies. In one embodiment, the launch lock assembly includes first and second mount pieces, a releasable clamp device, and an axial gap amplification device. The releasable clamp device normally maintains the first and second mount pieces in clamped engagement; and, when actuated, releases the first and second mount pieces from clamped engagement to allow relative axial motion there between. The axial gap amplification device normally residing in a blocking position wherein the gap amplification device obstructs relative axial motion between the first and second mount pieces. The axial gap amplification device moves into a non-blocking position when the first and second mount pieces are released from clamped engagement to increase the range of axial motion between the first and second mount pieces.
Test of critical heat flux with non-uniform axial power shapes in rectangle narrow channel
International Nuclear Information System (INIS)
Xiong Wanyu; Wang Fei; Xiao Zejun; Lu Donghua
2007-01-01
Critical heat flux for axial non-uniform heat flux distribution in rectangle narrow channel was studied in this report. During the test, electric heating were adopted, and the axial direction power loaded were truncation cosine distribution. The de-ionized water was heated. The test result indicated that CHF with non-uniform axial heat flux distribution was lower than CHF with uniform axial heat flux distribution. A correction factor was used to analyze the test data. The semi-empirical relation of correction factor of CHF with axial non-uniform heat flux distribution had been obtained. Comparing to the existing correction factor models, it revealed that the proposed semi-empirical relation predictive CHF with axial non-uniform heat flux distribution in rectangle narrow channel was most accurate. (authors)
Directory of Open Access Journals (Sweden)
Christopher Chukwutoo Ihueze
2017-01-01
Full Text Available This article employed the Hertz contact stress theory and the finite element method to evaluate the maximum contact pressure and the limit stresses of orange fruit under transportation and storage. The elastic properties of orange fruits subjected to axial and axial contact were measured such that elastic limit force, elastic modulus, Poisson’s ratio and bioyield stress were obtained as 18 N, 0.691 MPa, 0.367, 0.009 MPa for axial compression and for radial loading were 15.69 N, 0.645 MPa, 0.123, 0.010 MPa. The Hertz maximum contact pressure was estimated for axial and radial contacts as 0.036 MPa. The estimated limiting yield stress estimated as von Mises stresses for the induced surface stresses of the orange topologies varied from 0.005 MPa–0.03 MPa. Based on the distortion energy theory (DET the yield strength of orange fruit is recommended as 0.03 MPa while based on the maximum shear stress theory (MSST is 0.01 MPa for the design of orange transportation and storage system.
Precision Seismic Monitoring of Volcanic Eruptions at Axial Seamount
Waldhauser, F.; Wilcock, W. S. D.; Tolstoy, M.; Baillard, C.; Tan, Y. J.; Schaff, D. P.
2017-12-01
Seven permanent ocean bottom seismometers of the Ocean Observatories Initiative's real time cabled observatory at Axial Seamount off the coast of the western United States record seismic activity since 2014. The array captured the April 2015 eruption, shedding light on the detailed structure and dynamics of the volcano and the Juan de Fuca midocean ridge system (Wilcock et al., 2016). After a period of continuously increasing seismic activity primarily associated with the reactivation of caldera ring faults, and the subsequent seismic crisis on April 24, 2015 with 7000 recorded events that day, seismicity rates steadily declined and the array currently records an average of 5 events per day. Here we present results from ongoing efforts to automatically detect and precisely locate seismic events at Axial in real-time, providing the computational framework and fundamental data that will allow rapid characterization and analysis of spatio-temporal changes in seismogenic properties. We combine a kurtosis-based P- and S-phase onset picker and time domain cross-correlation detection and phase delay timing algorithms together with single-event and double-difference location methods to rapidly and precisely (tens of meters) compute the location and magnitudes of new events with respect to a 2-year long, high-resolution background catalog that includes nearly 100,000 events within a 5×5 km region. We extend the real-time double-difference location software DD-RT to efficiently handle the anticipated high-rate and high-density earthquake activity during future eruptions. The modular monitoring framework will allow real-time tracking of other seismic events such as tremors and sea-floor lava explosions that enable the timing and location of lava flows and thus guide response research cruises to the most interesting sites. Finally, rapid detection of eruption precursors and initiation will allow for adaptive sampling by the OOI instruments for optimal recording of future
Three-dimensional S-wave tomography under Axial Seamount
Baillard, C.; Wilcock, W. S. D.; Arnulf, A. F.; Tolstoy, M.; Waldhauser, F.
2017-12-01
Axial Seamount is a submarine volcano located at the intersection of the Juande Fuca Ridge and the Cobb-Eickelberg hotspot 500 km off the coast of thenorthwestern United States. The seamount, which rises 1 km above the seafloor, ischaracterized by a shallow caldera that is elongated in the N-S direction, measure 8km by 3 km and sits on top of a 14 km by 3 km magma reservoir. Two eruptive eventsin 1998 and 2011 motivated the deployment in 2014 of a real time cabled observatorywithin the Axial caldera, as part of the Ocean Observatories Initiative (OOI).Theobservatory includes a network of seven seismometers that span the southern half ofthe caldera. Five months after the observatory came on-line in November 2014, thevolcano erupted on April 24, 2015. Well over 100,000 events were located in thevicinity of the caldera, delineating an outward dipping ring fault that extends fromnear the surface to the magma body at 2 km depth and which accommodatesinflation and deflation of the volcano.The initial earthquake locations have beenobtained with a one-dimensional velocity model but the travel time residuals suggeststrong heterogeneities. A three-dimensional P-wave velocity model, obtained bycombining multichannel and ocean bottom seismometer refraction data, is being usedto refine locations but the three-dimensional S-wave structure is presently unknown.In most mid-ocean ridge settings, the distribution of earthquakes is not conducive forjoint inversions for S-wave velocity and hypocentral parameters because there are fewcrossing ray paths but at Axial the presence of a ring fault that is seismically active atall depths on both the east and west side of the caldera, provides a reasonablegeometry for such efforts. We will present the results of joint inversions that assumethe existing three-dimensional P wave velocity model and solve for VP/VS structure andhypocentral parameters using LOTOS, an algorithm that solves the forward problemusing ray bending.The resulting model
Spine and axial skeleton injuries in the National Football League.
Mall, Nathan A; Buchowski, Jacob; Zebala, Lukas; Brophy, Robert H; Wright, Rick W; Matava, Matthew J
2012-08-01
The majority of previous literature focusing on spinal injuries in American football players is centered around catastrophic injuries; however, this may underestimate the true number of these injuries in this athletic cohort. The goals of this study were to (1) report the incidence of spinal and axial skeleton injuries, both minor and severe, in the National Football League (NFL) over an 11-year period; (2) determine the incidence of spinal injury by injury type, anatomic location, player position, mechanism of injury, and type of exposure (practice vs game); and (3) determine the average number of practices and days missed because of injury for each injury type. Descriptive epidemiological study. All documented injuries to the cervical, thoracic, and lumbar spine; pelvis; ribs; and spinal cord were retrospectively analyzed using the NFL's injury surveillance database over a period of 11 seasons from 2000 through 2010. The data were analyzed by the number of injuries per athlete-exposure, the anatomic location and type of injury, player position, mechanism of injury, and number of days missed per injury. A total of 2208 injuries occurred to the spine or axial skeleton over an 11-season interval in the NFL, with a mean loss of 25.7 days per injury. This represented 7% of the total injuries during this time period. Of these 2208 injuries, 987 (44.7%) occurred in the cervical spine. Time missed from play was greatest for thoracic disc herniations (189 days/injury). Other injuries that had a mean time missed greater than 30 days included (in descending order) cervical fracture (120 days/injury), cervical disc degeneration/herniation (85 days/injury), spinal cord injury (77 days/injury), lumbar disc degeneration/herniation (52 days/injury), thoracic fracture (34 days/injury), and thoracic nerve injury (30 days/injury). Offensive linemen were the most likely to suffer a spinal injury, followed by defensive backs, defensive linemen, and linebackers. Blocking and tackling
Metamorphosis of helical magnetorotational instability in the presence axial electric current
Priede, Jānis
2014-01-01
This paper presents numerical linear stability analysis of a cylindrical Taylor-Couette flow of liquid metal carrying axial electric current in a generally helical external magnetic field. Axially symmetric disturbances are considered in the inductionless approximation corresponding to zero magnetic Prandtl number. Axial symmetry allows us to reveal an entirely new electromagnetic instability. First, we show that the electric current passing through the liquid can extend the range of helical ...
On the Application of Correction Factor for Axial Power Distribution to CHF Correlation Development
International Nuclear Information System (INIS)
Kim, Kang Hoon; Kim, Hong Ju; Yang, Seung Geun; Park, Eung Jun; Hwang, Sun Tack; Chung, Sun Kyo
2005-01-01
The axial heat flux distribution in nuclear reactors is invariably non-uniform. Thus it is very important to validate the general applicability of CHF correlation developed with limited types of axial heat flux distribution to actual situation of various axial power shapes in reactor operation. Per the recent fuel development, CHF testing is performed for chopped cosine axial heat flux distribution only. Thus it is inevitable to re-clarify the validity of correction factor for non-uniform axial heat flux distribution to support the general applicability of CHF correlation developed with data recently tested. Two ways of approach are considered to care the effects of axial power distribution in CHF correlation development. With the first method, CHF correlation is developed based on the data of uniform axial heat flux distribution only. To apply the correlation to the data of various axially non-uniform heat flux distribution, a factor such as Tong's F-factor is applied to the predicted value by the correlation itself to correct the effects of upstream memory on CHF. With the second approach, CHF correlation is developed based on whole data with the concept of equivalent uniform heat flux for the data of non-uniform axial heat flux distribution. The equivalent uniform heat flux is a measured CHF value for the data of uniform axial heat flux distribution, but it is a pseudo-CHF with a corrective factor for the data of non-uniform axial heat flux distribution. The corrective factor is applied to predict CHF for any non-uniform axial heat flux distribution
Effect of flow oscillations on axial energy transport in a porous material
Siegel, R.
1987-01-01
The effects of flow oscillations on axial energy diffusion in a porous medium, in which the flow is continuously disrupted by the irregularities of the porous structure, are analyzed. The formulation employs an internal heat transfer coefficient that couples the fluid and solid temperatures. The final relationship shows that the axial energy transport per unit cross-sectional area and time is directly proportional to the axial temperature gradient and the square of the maximum fluid displacement.
Atlanto-axial Subluxation in rheumatoid arthritis: description of a case
International Nuclear Information System (INIS)
Medina, Yimy F; Martinez V, Jose B; Restrepo, Jose Felix; Rondon H, Federico; Iglesias G, Antonio
2004-01-01
The damage of the spine by rheumatoid arthritis is multiple and a variety of affectations have been described at cervical level, being the anterior atlanto-axial subluxation and vertical subluxation the more common. However the posterior atlanto-axial subluxation has been rarely described. In this paper, we describe the case of a patient with posterior atlanto-axial subluxaction in addition to its infrequent manifestation of alteration of the lower cranial nerves as a manifestation of myelopathy
Precautions against axial fan stall in reactor building to Tianwan NPP
International Nuclear Information System (INIS)
Liu Chunlong; Pei Junmin
2011-01-01
The paper introduces the mechanism and harm of rotating stall of axial fans, analyzes the necessity for prevention against axial fan stall in reactor building of Tianwan NPP, introduces the precautions, and then makes an assessment on anti-stall effect of flow separators. It can provide reference for model-selection or reconstruction of similar fans in power stations, and for operation and maintenance of axial fans. (authors)
Kim, Ji-Beom; Yi, Young; Kim, Jae-Young; Cho, Jae-Ho; Kwon, Min-Soo; Choi, Seung-Hyuk; Lee, Woo-Chun
2017-08-01
To assess the incidence of abnormal internal rotation of the talus in the axial plane in patients with varus ankle osteoarthritis, and to determine whether this incidence differs from the severity of varus ankle osteoarthritis (moderate versus severe). We retrospectively evaluated weight-bearing computed tomography (CT) and plain radiographs of 52 ankles with no abnormalities (control group) and 96 ankles with varus osteoarthritis (varus-OA group), which were further stratified into a moderate-OA subgroup (50 ankles) and a severe-OA subgroup (46 ankles). A new radiographic parameter on weight-bearing CT, the talus rotation ratio, was used to assess the rotation of the talus in the axial plane. The normal range of the talus rotation ratio was defined as the 95% prediction interval for talus rotation ratio values in the control group. Abnormal internal rotation of the talus was defined for talus rotation ratio values above the normal range. We determined the incidence of abnormal internal rotation of the talus in the varus-OA group, moderate-OA subgroup, and severe-OA subgroup. In the varus-OA group, the incidence of abnormal internal rotation of the talus was 45% (43 ankles), which corresponded to an incidence of 32% (16 ankles) in the moderate-OA subgroup and 59% (27 ankles) in the severe-OA subgroup (p = 0.013). Our study demonstrates that abnormal internal rotation of the talus occurs in patients with varus ankle osteoarthritis, and is more frequently noted in severe than in moderate varus ankle osteoarthritis.
Energy Technology Data Exchange (ETDEWEB)
Kim, Ji-Beom; Yi, Young; Lee, Woo-Chun [Seoul Foot and Ankle Center, Dubalo Orthopaedic Clinic, Seochogu, Seoul (Korea, Republic of); Kim, Jae-Young; Kwon, Min-Soo; Choi, Seung-Hyuk [Inje University Seoul Paik Hospital, Department of Orthopaedic Surgery, Jung-gu, Seoul (Korea, Republic of); Cho, Jae-Ho [Hallym University, ChunCheon Sacred Heart Hospital, Department of Orthopaedic Surgery, Chuncheon, GangWon-do (Korea, Republic of)
2017-08-15
To assess the incidence of abnormal internal rotation of the talus in the axial plane in patients with varus ankle osteoarthritis, and to determine whether this incidence differs from the severity of varus ankle osteoarthritis (moderate versus severe). We retrospectively evaluated weight-bearing computed tomography (CT) and plain radiographs of 52 ankles with no abnormalities (control group) and 96 ankles with varus osteoarthritis (varus-OA group), which were further stratified into a moderate-OA subgroup (50 ankles) and a severe-OA subgroup (46 ankles). A new radiographic parameter on weight-bearing CT, the talus rotation ratio, was used to assess the rotation of the talus in the axial plane. The normal range of the talus rotation ratio was defined as the 95% prediction interval for talus rotation ratio values in the control group. Abnormal internal rotation of the talus was defined for talus rotation ratio values above the normal range. We determined the incidence of abnormal internal rotation of the talus in the varus-OA group, moderate-OA subgroup, and severe-OA subgroup. In the varus-OA group, the incidence of abnormal internal rotation of the talus was 45% (43 ankles), which corresponded to an incidence of 32% (16 ankles) in the moderate-OA subgroup and 59% (27 ankles) in the severe-OA subgroup (p = 0.013). Our study demonstrates that abnormal internal rotation of the talus occurs in patients with varus ankle osteoarthritis, and is more frequently noted in severe than in moderate varus ankle osteoarthritis. (orig.)
International Nuclear Information System (INIS)
Kim, Ji-Beom; Yi, Young; Lee, Woo-Chun; Kim, Jae-Young; Kwon, Min-Soo; Choi, Seung-Hyuk; Cho, Jae-Ho
2017-01-01
To assess the incidence of abnormal internal rotation of the talus in the axial plane in patients with varus ankle osteoarthritis, and to determine whether this incidence differs from the severity of varus ankle osteoarthritis (moderate versus severe). We retrospectively evaluated weight-bearing computed tomography (CT) and plain radiographs of 52 ankles with no abnormalities (control group) and 96 ankles with varus osteoarthritis (varus-OA group), which were further stratified into a moderate-OA subgroup (50 ankles) and a severe-OA subgroup (46 ankles). A new radiographic parameter on weight-bearing CT, the talus rotation ratio, was used to assess the rotation of the talus in the axial plane. The normal range of the talus rotation ratio was defined as the 95% prediction interval for talus rotation ratio values in the control group. Abnormal internal rotation of the talus was defined for talus rotation ratio values above the normal range. We determined the incidence of abnormal internal rotation of the talus in the varus-OA group, moderate-OA subgroup, and severe-OA subgroup. In the varus-OA group, the incidence of abnormal internal rotation of the talus was 45% (43 ankles), which corresponded to an incidence of 32% (16 ankles) in the moderate-OA subgroup and 59% (27 ankles) in the severe-OA subgroup (p = 0.013). Our study demonstrates that abnormal internal rotation of the talus occurs in patients with varus ankle osteoarthritis, and is more frequently noted in severe than in moderate varus ankle osteoarthritis. (orig.)
Fracture Analysis of Debonded Sandwich Columns Under Axial Compression
DEFF Research Database (Denmark)
May, A.; Avilés, F.; Berggreen, Christian
A sandwich structure consists of two strong and stiff face sheets bonded to a weak low density core. The large separation between the face sheets provides increased bending rigidity and strength at low weight cost. Thus, sandwich structures frequently present better mechanical properties than...... monolithic structures of the same weight. The vast range of applications of such materials includes wind turbines, marine, and aerospace industries. In this work, geometrically nonlinear finite element analysis is conducted to investigate the fracture parameters and debond propagation of sandwich columns...... containing a face-to-core debond subjected to axial compression. Bidimensional finite element models of sandwich columns containing different size debonds centered at one face/core interface were developed and used in conjunction with linear elastic fracture mechanics to predict the stress intensity factors...
A review of X-ray computed axial tomography
International Nuclear Information System (INIS)
Schmidt, M.
1989-01-01
A review of Computed axial tomography (CAT) scanning literature outlining the theoretical and practical aspects of this technique with application in both medical diagnosis and industrial non-destructive inspection (NDI) is presented. Practical aspects of CAT scanning discussed include : radiation sources, currently available spatial and contrast resolution limits and the evolution of the computerized tomography (CT) system. It was found that monochromatic gamma rays are preferred to X-rays, especially for very high density materials, and that in medical CAT scanning, the special resolution is only, 0.5 mm while spatial resolutions of less than 50μm have been achieved in NDI. An increased number of scientific and industrial applications are anticipated (e.g. for studying sintering reactions), as the capital cost of CAT scanning decreased. 13 refs., 9 figs., 2 tabs
Failure Processes in Embedded Monolayer Graphene under Axial Compression
Androulidakis, Charalampos; Koukaras, Emmanuel N.; Frank, Otakar; Tsoukleri, Georgia; Sfyris, Dimitris; Parthenios, John; Pugno, Nicola; Papagelis, Konstantinos; Novoselov, Kostya S.; Galiotis, Costas
2014-01-01
Exfoliated monolayer graphene flakes were embedded in a polymer matrix and loaded under axial compression. By monitoring the shifts of the 2D Raman phonons of rectangular flakes of various sizes under load, the critical strain to failure was determined. Prior to loading care was taken for the examined area of the flake to be free of residual stresses. The critical strain values for first failure were found to be independent of flake size at a mean value of –0.60% corresponding to a yield stress up to -6 GPa. By combining Euler mechanics with a Winkler approach, we show that unlike buckling in air, the presence of the polymer constraint results in graphene buckling at a fixed value of strain with an estimated wrinkle wavelength of the order of 1–2 nm. These results were compared with DFT computations performed on analogue coronene/PMMA oligomers and a reasonable agreement was obtained. PMID:24920340
Stress Analysis of Fuel Rod under Axial Coolant Flow
International Nuclear Information System (INIS)
Jin, Hai Lan; Lee, Young Shin; Lee, Hyun Seung; Park, Num Kyu; Jeon, Kyung Rok
2010-01-01
A pressurized water reactor(PWR) fuel assembly, is a typical bundle structure, which uses light water as a coolant in most commercial nuclear power plants. Fuel rods that have a very slender and long clad are supported by fuel assembly which consists of several spacer grids. A coolant is a fluid which flows through device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. But at the same time, the coolant flow will bring out the fluid induced vibration(FIV) of fuel rods and even damaged the fuel rod. This study has been conducted to investigate the flow characteristics and nuclear reactor fuel rod stress under effect of coolant. Fluid structure interaction(FSI) analysis on nuclear reactor fuel rod was performed. Fluid analysis of the coolant which flow along the axial direction and structural analysis under effect of flow velocity were carried out under different output flow velocity conditions
Computerized axial tomography in the detection of brain damage
International Nuclear Information System (INIS)
Cala, L.A.; Mastaglia, F.L.
1980-01-01
The cranial computerized axial tomography (CAT) findings in groups of patients with epilepsy, migraine, hypertension, and other general medical disorders have been reviewed to assess the frequency and patterns of focal and diffuse brain damage. In addition to demonstrating focal lesions in a proportion of patients with seizures and in patients presenting with a stroke, the CAT scan showed a premature degree of cerebral atrophy in an appreciable proportion of patients with long-standing epilepsy, hypertension and diabetes, and in some patients with migraine, valvular and ischaemic heart disease, chronic obstructive airways disease, and chronic renal failure. The value of CAT as a means of screening for brain damage in groups of individuals at risk is discussed
Predicting the Coupling Properties of Axially-Textured Materials
Directory of Open Access Journals (Sweden)
María E. Fuentes-Montero
2013-10-01
Full Text Available A description of methods and computer programs for the prediction of “coupling properties” in axially-textured polycrystals is presented. Starting data are the single-crystal properties, texture and stereography. The validity and proper protocols for applying the Voigt, Reuss and Hill approximations to estimate coupling properties effective values is analyzed. Working algorithms for predicting mentioned averages are given. Bunge’s symmetrized spherical harmonics expansion of orientation distribution functions, inverse pole figures and (single and polycrystals physical properties is applied in all stages of the proposed methodology. The established mathematical route has been systematized in a working computer program. The discussion of piezoelectricity in a representative textured ferro-piezoelectric ceramic illustrates the application of the proposed methodology. Polycrystal coupling properties, predicted by the suggested route, are fairly close to experimentally measured ones.
Plasticity around an Axial Surface Crack in a Cylindrical Shell
DEFF Research Database (Denmark)
Krenk, Steen
1979-01-01
field in an axially cracked cylindrical shell arising from use of classical eighth order shallow shell theory is removed when use is made of a tenth order shell theory which accounts for transverse shear deformations. Although the membrane stresses are only moderately affected, the influence...... and Ratwani,3–5 it generalises Dugdale's assumption of a concentrated yield zone in the plane of the crack but, contrary to that model, transverse shear effects are included and a continuous stress distribution is assumed in the yield zone. The inherent difficulties arising from the use of shell theory...... of the yield zone. The model is used to analyse published test data on surface cracked pressurised pipes. The analysis consists in COD evaluation and estimate of failure as a consequence of plastic instability. A method is proposed which deals with the problem by simultaneous analysis of a number of cracks...
Treatment with tumor necrosis factor inhibitors in axial spondyloarthritis
DEFF Research Database (Denmark)
Ciurea, A.; Weber, U.; Stekhoven, D.
2015-01-01
in private practices in comparison to academic centers, adherence to ASAS treatment recommendations for TNF inhibition was equally high, and similar response rates to TNF blockers were achieved in both clinical settings. (First Release Nov 1 2014; J Rheumatol 2015; 42:101-5; doi 10.3899/jrheum.140229).......Objective. To evaluate the initiation of and response to tumor necrosis factor (TNF) inhibitors for axial spondyloarthritis (axSpA) in private rheumatology practices versus academic centers. The Journal of Rheumatology, Methods.We compared newly initiated TNF inhibition for axSpA in 363 patients...... was slightly higher in the hospital setting. Mean levels (+/- SD) of the Ankylosing Spondylitis Disease Activity Score were, however, virtually identical in private practices and academic centers (3.4 +/- 1.0 vs 3.4 +/- 0.9, p = 0.68). An Assessment of SpondyloArthritis international Society (ASAS40) response...
Study of axial protections of unloading machines of graphite piles
International Nuclear Information System (INIS)
Duco, Jacques; Pepin, Pierre; Cabaret, Guy; Dubor, Monique
1969-10-01
As previous studies resulted in the development of a simple calculation formula based on experimental results for the calculation of neutron protection thicknesses for loading machines, this study aimed at determining axial protections of these machines which represent a specific problem: scattering of delayed neutrons in the machine inner cavity may result in an important neutron leakage through the upper part, at the level of the winch enclosure. In an experimental part, this study comprises the measurement of the neutron dose in a 2.60 m long and 54 cm diameter cylindrical cavity, and in the thickness of the surrounding concrete protection. In the second part, the authors present a calculation method which uses the Zeus and Mercure codes to interpret the results [fr
Endoscopic Transoral Resection of an Axial Chordoma: A Case Report
Directory of Open Access Journals (Sweden)
Taran S
2015-11-01
Full Text Available Upper cervical chordoma (UCC is rare condition and poses unique challenges to surgeons. Even though transoral approach is commonly employed, a minimally invasive technique has not been established. We report a 44-year old Malay lady who presented with a 1 month history of insidious onset of progressive neck pain without neurological symptoms. She was diagnosed to have an axial (C2 chordoma. Intralesional resection of the tumour was performed transorally using the Destandau endoscopic system (Storz, Germany. Satisfactory intralesional excision of the tumour was achieved. She had a posterior fixation of C1-C4 prior to that. Her symptoms improved postoperatively and there were no complications noted. She underwent adjuvant radiotherapy to minimize local recurrence. Endoscopic excision of UCC via the transoral approach is a safe option as it provides an excellent magnified view and ease of resection while minimizing the operative morbidity.
Active surge control for variable speed axial compressors.
Lin, Shu; Yang, Chunjie; Wu, Ping; Song, Zhihuan
2014-09-01
This paper discusses active surge control in variable speed axial compressors. A compression system equipped with a variable area throttle is investigated. Based on a given compressor model, a fuzzy logic controller is designed for surge control and a proportional speed controller is used for speed control. The fuzzy controller uses measurements of the change of pressure rise as well as the change of mass flow to determine the throttle opening. The presented approach does not require the knowledge of system equilibrium or the surge line. Numerical simulations show promising results. The proposed fuzzy logic controller performs better than a backstepping controller and is capable to suppress surge at different operating points. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
Hamilton's equations for a fluid membrane: axial symmetry
International Nuclear Information System (INIS)
Capovilla, R; Guven, J; Rojas, E
2005-01-01
Consider a homogeneous fluid membrane, or vesicle, described by the Helfrich-Canham energy, quadratic in the mean curvature. When the membrane is axially symmetric, this energy can be viewed as an 'action' describing the motion of a particle; the contours of equilibrium geometries are identified with particle trajectories. A novel Hamiltonian formulation of the problem is presented which exhibits the following two features: (i) the second derivatives appearing in the action through the mean curvature are accommodated in a natural phase space and (ii) the intrinsic freedom associated with the choice of evolution parameter along the contour is preserved. As a result, the phase space involves momenta conjugate not only to the particle position but also to its velocity, and there are constraints on the phase space variables. This formulation provides the groundwork for a field theoretical generalization to arbitrary configurations, with the particle replaced by a loop in space
Axial shape index calculation for the 3-level excore detector
Energy Technology Data Exchange (ETDEWEB)
Kim, Han Gon; Kim, Yong Hee; Kim, Byung Sop; Lee, Sang Hee; Cho, Sung Jae [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
1997-12-31
A new method based on the alternating conditional expectation (ACE) algorithm is developed to calculate axial shape index (ASI) for the 3-level excore detector. The ACE algorithm, a type of nonparametric regression algorithms, yields an optimal relationship between a dependent variable and multiple independent variables. In this study, the simple correlation between ASI and excore detector signals is developed using the Younggwang nuclear power plant unit 3 (YGN-3) data without any preprocessing on the relationships between independent variables and dependent variable. The numerical results show that simple correlations exist between the three excore signals and ASI of the core. The accuracy of the new method is much better than those of the current CPC and COLSS algorithms. 5 refs., 2 figs., 2 tabs. (Author)
Structures of water molecular nanotube induced by axial tensile strains
Energy Technology Data Exchange (ETDEWEB)
Li, H. [Key Laboratory of Liquid Structures and Heredity of Materials, Ministry of Education, School of Materials Science and Engineering, Shandong University (China)], E-mail: lihuilmy@hotmail.com; Zhang, X.Q. [Physics Department, Ocean University of China, Qingdao (China); Liew, K.M. [Department of Building and Constructions, City University of Hong Kong, Kowloon (Hong Kong); Liu, X.F. [Key Laboratory of Liquid Structures and Heredity of Materials, Ministry of Education, School of Materials Science and Engineering, Shandong University (China)
2008-10-06
Five well-ordered nano-ice structures embedded in carbon nanotubes are obtained in this study. These five nano-ice phases all exhibit single walled tubular morphologies, including the pentagon, hexagon ice nanotubes whose structures are quite different from bulk ice. Our simulation results indicate that water molecules tend to rearrange into surface ring structures to reduce the number of free OH groups. The structural behavior of these ice nanotubes inside CNTs subject to axial stress is also investigated. The ice nanotubes tend to be drawn to ice nanorings or ice nanospring during the mechanical stretching. The distribution function exhibits typical order-to-disorder transition of the water network confined in carbon nanotube during the stretching. By analysis, we suggest that it is unlikely that additional water molecules will enter the tubes because of the increased volume available if the tubes are stretched at contact with a water reservoir.
Axial-flow turbines for low head microhydro systems
Energy Technology Data Exchange (ETDEWEB)
Alexander, K.V.; Fuller, A.M. [Department of Mechanical Engineering, University of Canterbury, PB 4800, Christchurch (New Zealand); Giddens, E.P. [Department of Civil Engineering, University of Canterbury, Christchurch (New Zealand)
2009-01-15
This paper describes the design of four different specific speed microhydro propeller turbines operating at heads between 4 m and 9 m, and their application to a wider range of heads and outputs by scaling. The features are specifically tailored for ease of manufacture and uniquely resistant to debris blockage. Test machines are described and test results given; hydraulic efficiencies of over 68% have been achieved in all test models despite the fact that these turbines' blades are planar, further simplifying manufacture. Theoretical models show how closely these flat blades can be made to approach the ideal blade shapes. Outline drawings are given with key dimensions for each reference model, along with the equations for scaling to arbitrary sites. These turbines are the axial flow members of a family of turbines developed to cover the microhydro range from 2 m to about 40 m of head. (author)
A cryogenic axial-centrifugal compressor for superfluid helium refrigeration
Decker, L; Schustr, P; Vins, M; Brunovsky, I; Lebrun, P; Tavian, L
1997-01-01
CERN's new project, the Large Hadron Collider (LHC), will use superfluid helium as coolant for its high-field superconducting magnets and therefore require large capacity refrigeration at 1.8 K. This may only be achieved by subatmospheric compression of gaseous helium at cryogenic temperature. To stimulate development of this technology, CERN has procured from industry prototype Cold Compressor Units (CCU). This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating under low-pressure helium at ambient temperature. The machine has been commissioned and is now in operation. After describing basic constructional features of the compressor, we report on measured performance.
Control of hole localization in magnetic semiconductors by axial strain
Raebiger, Hannes; Bae, Soungmin; Echeverría-Arrondo, Carlos; Ayuela, Andrés
2018-02-01
Mn and Fe-doped GaN are widely studied prototype systems for hole-mediated magnetic semiconductors. The nature of the hole states around the Mn and Fe impurities, however, remains under debate. Our self-interaction corrected density-functional calculations show that the charge neutral Mn 0 and positively charged Fe+ impurities have symmetry-broken d5+h ground states, in which the hole is trapped by one of the surrounding N atoms in a small polaron state. We further show that both systems also have a variety of other d5+h configurations, including symmetric, delocalized states, which may be stabilized by axial strain. This finding opens a pathway to promote long-range hole-mediated magnetic interactions by strain engineering and clarifies why highly strained thin-films samples often exhibit anomalous magnetic properties.
Operational Experience with a Cryogenic Axial-Centrifugal Compressor
Decker, L; Löhlein, K; Purtschert, W; Ziegler, B L; Lebrun, P; Tavian, L; Brunovsky, I; Tucek, L
1998-01-01
The Large Hadron Collider (LHC), presently under construction at CERN, requires large refrigeration capacity at 1.8 K. Compression of gaseous helium at cryogenic temperatures is therefore inevitable. Together with subcontractors, Linde Kryotechnik has developed a prototype machine. This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating at ambient temperature. Integrated in a test facility for superconducting magnets the machine has been commissioned without major problems and successfully gone through the acceptance test in autumn 1995. Subsequent steps were initiated to improve efficiency of this prototype. This paper describes operating experience gained so far and reports on measured performance prior to and after constructional modifications.
Experimental investigation of axially aligned flow past spinning cylinders
Carlucci, Pasquale; Buckley, Liam; Mehmedagic, Igbal; Carlucci, Donald; Thangam, Siva
2016-11-01
Experimental and numerical results of ongoing subsonic investigations of the flow field about axially aligned spinning cylinders with variable inter-cylinder spacing are presented. The experimental design is capable of investigating wake dynamics of the modeled system up to a Reynolds Number of 300,000 and rotation numbers up to 2. The experimental results are used to validate and confirm numerical simulations with and without the effects of swirl. The focus of the overall effort is an understanding of the dynamics of multi-body problems in a flow field, as such we relate the ongoing effort to previous studies by both the authors and the community at large and our ongoing work in developing accurate plant models for use in engineering analysis and design. Funded in part by U. S. Army ARDEC, Picatinny Arsenal, NJ.
Computer aided hydraulic design of axial flow pump impeller
International Nuclear Information System (INIS)
Sreedhar, B.K.; Rao, A.S.L.K.; Kumaraswamy, S.
1994-01-01
Pumps are the heart of any power plant and hence their design requires great attention. Computers with their potential for rapid computation can be successfully employed in the design and manufacture of these machines. The paper discusses a program developed for the hydraulic design of axial flow pump impeller. The program, written in FORTRAN 77, is interactive and performs the functions of design calculation, drafting and generation of numerical data for blade manufacture. The drafting function, which makes use of the software ACAD, is carried out automatically by means of suitable interface programs. In addition data for blade manufacture is also generated in either the x-y-z or r-θ-z system. (author). 4 refs., 3 figs
Gearbox Instrumentation for the Investigation of Bearing Axial Cracking
Energy Technology Data Exchange (ETDEWEB)
Keller, Jonathan A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lambert, Scott R [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2018-03-27
Failures in gearbox bearings have been the primary source of reliability issues for wind turbine drivetrains, leading to costly downtime and unplanned maintenance. The most common failure mode is attributed to so-called axial cracks or white-etching cracks, which primarily affect the intermediate and high-speed-stage bearings. The high-speed-shaft and bearing loads and sliding will be measured with a specially instrumented gearbox installed in a 1.5-megawatt turbine at the National Wind Technology Center in an upcoming test campaign. Additional instrumentation will also measure the tribological environment of these bearings, including bearing temperatures, lubricant temperature and water content, air temperature and humidity, and stray electrical current across the bearings. This paper fully describes the instrumentation package and summarizes initial results.
Axial-resolution in depth from focus digital holography
van Rooij, Joseph; Kalkman, Jeroen
2017-06-01
We use digital holography to quantify surface topography of rough objects in full-field. We calculate the variance of the intensity image as a focus metric over a set of reconstruction distances for each pixel, which results in a focus metric curve. The distance where the variance peaks is an estimate for the depth. First we analyze the lateral resolution of this method using the Talbot effect and argue that sub-mm axial resolution is feasible. Then, using a Michelson setup without magnifying optics or lateral scanning we experimentally demonstrate that sub-mm FWHM width of the focus curve can be achieved. This is significantly better than what was previously reported using digital holography and could make this technique useful for characterising objects in art and machine vision.
Chondrocyte activity is increased in psoriatic arthritis and axial spondyloarthritis
DEFF Research Database (Denmark)
Gudmann, Natasja Stæhr; Munk, Heidi Lausten; Christensen, Anne Friesgaard
2016-01-01
BACKGROUND: Psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA) are chronic inflammatory rheumatic diseases with complex origins. Both are characterized by altered extracellular matrix remodeling in joints and entheses that results in destructive and osteochondral proliferative lesions.......30 ng/ml, 0.16-0.41) (p treatment. C-Col10 was slightly but equally elevated in the PsA and axSpA groups vs. the control group, but it was significantly lower in patients with axSpA undergoing tumor necrosis factor-α inhibitor (TNFi) treatment. ROC curve......SpA undergoing TNFi treatment may reflect that hypertrophic chondrocytes in axSpA are targeted by TNFi. ROC curve analysis showed a diagnostic potential for Pro-C2 in axSpA and PsA....
Dynamic Electromechanical Characterization of Axially Poled PZT 95/5
International Nuclear Information System (INIS)
Chhabildas, Lalit C.; Furnish, Michael D.; Montgomery, Stephen T.; Setchell, Robert E.
1999-01-01
We are conducting a comprehensive experimental study of the electromechanical behavior of poled PZT 95/5 (lead zirconate titanate). As part of this study, eight plane-wave tests have been conducted on axially poled PZT 95/5 at stress levels ranging from 0.9 to 4.6 GPa, using VISAR and electrical diagnostics. Observed wave velocities were slightly decreased from ultrasonic velocity, by contrast' with unpoled samples. Compression waveforms show a step at 0.6 GPa more marked than for normally poled or unpoled samples; this may correspond to a poling effect on the ferroelectric/antiferroelectric transition. A similar step is observed on release. The released charge upon loading to 0.9 GPa is consistent with nearly complete depoling. Loading to higher stresses gave lower currents (factor of 10), suggesting shock-induced conductivity or electrical breakdown
Ishiguro, Toshitaka; Hiyama, Takashi; Nasu, Katsuhiro; Akashi, Yoshimasa; Minami, Manabu
2017-07-01
Gastrointestinal volvulus is mainly classified into two subtypes, mesentero-axial volvulus and organo-axial volvulus. The detailed imaging findings of organo-axial volvulus of the small intestine have never been reported as far as we know. In this article, we report a case of organo-axial volvulus of the small intestine, focusing on the computed tomography (CT) findings. An 80-year-old man was radiologically diagnosed as having organo-axial volvulus of the terminal ileum and it was confirmed by open surgery without adhesion or any other anatomical abnormalities. CT showed two specific findings, split-bowel sign and rotating-C sign, which we think reflect pathophysiologic features of organo-axial volvulus. We think the pathogenic mechanism of organo-axial volvulus can be explained by the convergence of the reversed-rotational twist following the formation of a twisted but non-obstructive circular loop, even if there is no adhesion. Radiologists should be aware that organo-axial volvulus can occur even in the small intestine, and in the case of small bowel obstruction with single transition point, the two pathophysiologic signs mentioned above must be looked for to diagnose the possibility of organo-axial volvulus.
Zhan, Jiao; Lin, Haotian; Zhang, Xinyu; Chen, Weirong; Liu, Yizhi
2013-06-01
Congenital cataract is the main cause of blindness in children, with significantly varying treatment effects. The development of axial length is an important factor that affects the prognosis of these children. However, when compared with the eyes of normal children, the mechanism of growth of the axial length is so complicated that the reported findings differ significantly in terms of the measuring apparatus, assessment methods, and statistical outcome, making the rule of axial length development still unclear. In this paper, we first review the process of axial length development in normal healthy children and compare different hypotheses about certain factors that could affect the development of axial length. The results of some current research about the characteristics of axial length development in congenital cataract children are then reviewed. Lastly, the advantages and disadvantages of current axial length measurements methods are compared and analyzed. The purpose of this review is to improve our understanding of the complexity and importance of axial length development and to suggest better use of axial length monitoring measurements in congenital cataract children for pediatric ophthalmologists, with the hope of offering assistance that will enhance long-term therapeutic effects for these children.
Fuel rod with axial regions of annular and standard fuel pellets
International Nuclear Information System (INIS)
Freeman, T.R.
1991-01-01
This patent describes a fuel rod for use in a nuclear reactor fuel assembly. It comprises: an elongated hollow cladding tube; a pair of end plugs connected to and sealing the cladding tube at opposite ends of thereof; and an axial stack of fuel pellets contained in and extending between the end plugs at the opposite ends of the tube, all of the fuel pellets contained in the tube being composed of fissile material being enriched above the level of natural enrichment; the fuel pellets in the stack thereof being provided in an arrangement of axial regions. The arrangement of axial regions including a pair of first axial regions defined respectively at the opposite ends of the pellet stack adjacent to the respective end plugs. The pellets in the first axial regions being identical in number and having annular configurations with an annulus of a first void size. The arrangement of axial regions also including another axial region defined between the first axial regions, some of the pellets in the another axial region having solid configurations
White matter biomarkers from fast protocols using axially symmetric diffusion kurtosis imaging
DEFF Research Database (Denmark)
Hansen, Brian; Khan, Ahmad R.; Shemesh, Noam
2016-01-01
progressing diseases. Here, we evaluate WMTI based on recently introduced axially symmetric DKI which has lower data demand than conventional DKI. We compare WMTI parameters derived from conventional DKI to those from axially symmetric DKI and to parameters calculated analytically from the axially symmetric...... tensors. We also assess the effect of the imposed symmetry on the kurtosis fractional anisotropy (KFA). We employ numerical simulations, as well as data from fixed rat spinal cord and whole human brain in vivo. Our analysis shows that analytical WMTI based on axially symmetric DKI with sparse data sets...
Molecular dynamics study of nanojoining between axially positioned Ag nanowires
International Nuclear Information System (INIS)
Cui, Jianlei; Theogene, Barayavuga; Wang, Xuewen; Mei, Xuesong; Wang, Wenjun; Wang, Kedian
2016-01-01
Highlights: • The temperature and distance have a great impact on joining effect without solders. • At high temperature, Ag atoms are disordered and the atomic queues become to distort. • When the distance is large, the Ag nanowires are not connected at any temperature. • When the distance is small and the temperature is low, Ag NWs on the Si substrate can be obtained relatively good nanoconnection. - Abstract: The miniaturization of electronics devices into nanometer scale is indispensable for next-generation semiconductor technology. Ag nanowires (Ag NWs) are considered to be the promising candidates for future electronic circuit owing to the excellent electrical and thermal properties. The nanojoining of axially positioned Ag NWs was performed by molecular dynamics simulation. Through the detailed atomic evolution during the nanojoining, the results indicate that the temperature and the distance between Ag NWs in axial direction have a great impact on nanojoining effect. When the nanojoining temperature is relatively high, the atoms are disordered and the atomic queues become to distort with strong thermodynamic properties and weak effect of metal bonds. At the relatively low temperature, the Ag NWs can be well connected with good junction quality and their own morphology, which is similar to the cold welding without fusion, while the distance between Ag NWs should be controlled for interaction and diffusion of interfacial atoms at nanowires head. When the Ag NWs are placed on Si and SiO 2 substrate, because the atomic species and lattice structure of substrate material can differently affect the motions of Ag atoms through the interactive force between the atoms, the nanojoining quality of Ag NWs on Si substrate is better than that on the SiO 2 substrate. So, for getting effective and reliable nanojoining without nanosolders and other materials, the temperature, distance and substrate surface should be reasonably controlled and selected, providing
Molecular dynamics study of nanojoining between axially positioned Ag nanowires
Energy Technology Data Exchange (ETDEWEB)
Cui, Jianlei, E-mail: cjlxjtu@xjtu.edu.cn [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Theogene, Barayavuga, E-mail: 1400584887@qq.com [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Wang, Xuewen, E-mail: 358994796@qq.com [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Mei, Xuesong, E-mail: xsmeixjtu@163.com [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Wenjun, E-mail: wangwenjun1981@yeah.net [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Kedian, E-mail: kedianwang@yeah.net [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)
2016-08-15
Highlights: • The temperature and distance have a great impact on joining effect without solders. • At high temperature, Ag atoms are disordered and the atomic queues become to distort. • When the distance is large, the Ag nanowires are not connected at any temperature. • When the distance is small and the temperature is low, Ag NWs on the Si substrate can be obtained relatively good nanoconnection. - Abstract: The miniaturization of electronics devices into nanometer scale is indispensable for next-generation semiconductor technology. Ag nanowires (Ag NWs) are considered to be the promising candidates for future electronic circuit owing to the excellent electrical and thermal properties. The nanojoining of axially positioned Ag NWs was performed by molecular dynamics simulation. Through the detailed atomic evolution during the nanojoining, the results indicate that the temperature and the distance between Ag NWs in axial direction have a great impact on nanojoining effect. When the nanojoining temperature is relatively high, the atoms are disordered and the atomic queues become to distort with strong thermodynamic properties and weak effect of metal bonds. At the relatively low temperature, the Ag NWs can be well connected with good junction quality and their own morphology, which is similar to the cold welding without fusion, while the distance between Ag NWs should be controlled for interaction and diffusion of interfacial atoms at nanowires head. When the Ag NWs are placed on Si and SiO{sub 2} substrate, because the atomic species and lattice structure of substrate material can differently affect the motions of Ag atoms through the interactive force between the atoms, the nanojoining quality of Ag NWs on Si substrate is better than that on the SiO{sub 2} substrate. So, for getting effective and reliable nanojoining without nanosolders and other materials, the temperature, distance and substrate surface should be reasonably controlled and selected
Axial Magnetic Field Compression in Laboratory Plasma Jets
Byvank, Tom; Potter, William; Greenly, John; Seyler, Charles; Kusse, Bruce
2017-10-01
Compression of an axial magnetic field correlates with density hollowing and azimuthal rotation of a plasma jet generated by the COBRA pulsed power machine (1 MA peak current in 100 ns rise time) in a radial foil (thin disk of 15 μm Al or Ti) configuration. The plasma jet compresses an initially uniform 1 T axial magnetic field (Bz) as it collimates along the central z-axis. Experimental measurements use a Bdot magnetic probe placed in the center of the hollow plasma jet. Experimental results show compression of an applied 1.0 +/-0.1 T Bz to 2.4 +/-0.3 T with aluminum jets and to 2.2 +/-0.2 T with titanium jets. Predictions made by the extended magnetohydrodynamics (XMHD) code, PERSEUS, show compression to a 3.4 T Bz at the probe location for aluminum plasmas. For titanium plasmas, implementing radiation into the code is in progress. Additionally using the XMHD simulation, we explore the effects of changing current directions and how the magnetic field being tied to the electrons in Hall MHD (rather than being frozen to the ions in ideal MHD) influences the magnetic field advection. We overview physical reasons for the discrepancy between the experimental and simulation magnetic field compression measurements, including: surface plasma on Bdot probes, 2D and 3D simulation effects, and differences between ablation of a solid foil compared to a foil initialized as a plasma. Work supported by NNSA SSAP under DOE Cooperative Agreement DE-NA0001836 and NSF Grant PHY-1102471.
Axial magnetic field injection in magnetized liner inertial fusion
Gourdain, P.-A.; Adams, M. B.; Davies, J. R.; Seyler, C. E.
2017-10-01
MagLIF is a fusion concept using a Z-pinch implosion to reach thermonuclear fusion. In current experiments, the implosion is driven by the Z-machine using 19 MA of electrical current with a rise time of 100 ns. MagLIF requires an initial axial magnetic field of 30 T to reduce heat losses to the liner wall during compression and to confine alpha particles during fusion burn. This field is generated well before the current ramp starts and needs to penetrate the transmission lines of the pulsed-power generator, as well as the liner itself. Consequently, the axial field rise time must exceed hundreds of microseconds. Any coil capable of being submitted to such a field for that length of time is inevitably bulky. The space required to fit the coil near the liner, increases the inductance of the load. In turn, the total current delivered to the load decreases since the voltage is limited by driver design. Yet, the large amount of current provided by the Z-machine can be used to produce the required 30 T field by tilting the return current posts surrounding the liner, eliminating the need for a separate coil. However, the problem now is the field penetration time, across the liner wall. This paper discusses why skin effect arguments do not hold in the presence of resistivity gradients. Numerical simulations show that fields larger than 30 T can diffuse across the liner wall in less than 60 ns, demonstrating that external coils can be replaced by return current posts with optimal helicity.
Axial ion-electron emission microscopy of IC radiation hardness
Doyle, B. L.; Vizkelethy, G.; Walsh, D. S.; Swenson, D.
2002-05-01
A new system for performing radiation effects microscopy (REM) has been developed at Sandia National Laboratory in Albuquerque. This system combines two entirely new concepts in accelerator physics and nuclear microscopy. A radio frequency quadrupole (RFQ) linac is used to boost the energy of ions accelerated by a conventional Tandem Van de Graaff-Pelletron to velocities of 1.9 MeV/amu. The electronic stopping power for heavy ions is near a maximum at this velocity, and their range is ˜20 μm in Si. These ions therefore represent the most ionizing form of radiation in nature, and are nearly ideal for performing single event effects testing of integrated circuits. Unfortunately, the energy definition of the RFQ-boosted ions is rather poor (˜ a few %), which makes problematic the focussing of such ions to the submicron spots required for REM. To circumvent this problem, we have invented ion electron emission microscopy (IEEM). One can perform REM with the IEEM system without focussing or scanning the ion beam. This is because the position on the sample where each ion strikes is determined by projecting ion-induced secondary electrons at high magnification onto a single electron position sensitive detector. This position signal is then correlated with each REM event. The IEEM system is now mounted along the beam line in an axial geometry so that the ions pass right through the electron detector (which is annular), and all of the electrostatic lenses used for projection. The beam then strikes the sample at normal incidence which results in maximum ion penetration and removes a parallax problem experienced in an earlier system. Details of both the RFQ-booster and the new axial IEEM system are given together with some of the initial results of performing REM on Sandia-manufactured radiation hardened integrated circuits.
Hysteretic Models Considering Axial-Shear-Flexure Interaction
Ceresa, Paola; Negrisoli, Giorgio
2017-10-01
Most of the existing numerical models implemented in finite element (FE) software, at the current state of the art, are not capable to describe, with enough reliability, the interaction between axial, shear and flexural actions under cyclic loading (e.g. seismic actions), neglecting crucial effects for predicting the nature of the collapse of reinforced concrete (RC) structural elements. Just a few existing 3D volume models or fibre beam models can lead to a quite accurate response, but they are still computationally inefficient for typical applications in earthquake engineering and also characterized by very complex formulation. Thus, discrete models with lumped plasticity hinges may be the preferred choice for modelling the hysteretic behaviour due to cyclic loading conditions, in particular with reference to its implementation in a commercial software package. These considerations lead to this research work focused on the development of a model for RC beam-column elements able to consider degradation effects and interaction between the actions under cyclic loading conditions. In order to develop a model for a general 3D discrete hinge element able to take into account the axial-shear-flexural interaction, it is necessary to provide an implementation which involves a corrector-predictor iterative scheme. Furthermore, a reliable constitutive model based on damage plasticity theory is formulated and implemented for its numerical validation. Aim of this research work is to provide the formulation of a numerical model, which will allow implementation within a FE software package for nonlinear cyclic analysis of RC structural members. The developed model accounts for stiffness degradation effect and stiffness recovery for loading reversal.
Study of Axially-Laminated Anisotropic Rotor Reluctance Synchronous Machine and its Drive
Fu, Zhenxing
1991-02-01
This dissertation presents a relatively comprehensive study of 2-pole axially-laminated anisotropic (ALA) rotor reluctance synchronous machine in both motoring and generating modes. The theory, analysis techniques, and vector control strategies developed can be applied to other types of reluctance synchronous machines as well, with or without corresponding modifications. Space phasor models of the machine in stator or rotor coordinates are presented. Steady state performance, such as, maximum power factor and efficiency are studied. Transient torque capabilities for constant stator flux, current, and voltage are investigated together with transient state operations. Analytical determinations of d-axis and q -axis magnetic fields, and the corresponding inductances are presented. FEM numerical magnetic field analysis along the d-axis and q-axis is performed for refined design and parameter estimations. To meet the desired performance and high d-axis to q-axis inductances ratio from axially -laminated anisotropic rotor, multi-slot per phase per pole should be used. Experimental tests of the machine in both motoring and generating modes are performed, a high d-axis to q-axis inductances ratio of 21.3 and a maximum power factor of 0.914 and a maximum efficiency of 94% are obtained. Novel current vector control and torque vector control schemes are developed with extensive digital simulations. Sliding mode controller is used and compared with PI controller. Torque vector control principles and stator flux and torque estimation techniques are presented together with the table of optimal voltage vector switchings. A wide controllable speed range of 0.1 rpm to 5000 rpm (for current vector control) and 0.2 rpm to 12000 rpm (for torque vector control) are obtained. The dynamics of the vector controlled drive are fast and relatively robust. A novel fuzzy knowledge-based sensorless dc output voltage control of ALA-rotor reluctance generator is developed and digitally simulated
Large Aspect Ratio Tokamak Study
International Nuclear Information System (INIS)
Reid, R.L.; Holmes, J.A.; Houlberg, W.A.; Peng, Y.K.M.; Strickler, D.J.; Brown, T.G.; Wiseman, G.W.
1980-06-01
The Large Aspect Ratio Tokamak Study (LARTS) at Oak Ridge National Laboratory (ORNL) investigated the potential for producing a viable longburn tokamak reactor by enhancing the volt-second capability of the ohmic heating transformer through the use of high aspect ratio designs. The plasma physics, engineering, and economic implications of high aspect ratio tokamaks were assessed in the context of extended burn operation. Using a one-dimensional transport code plasma startup and burn parameters were addressed. The pulsed electrical power requirements for the poloidal field system, which have a major impact on reactor economics, were minimized by optimizing the startup and shutdown portions of the tokamak cycle. A representative large aspect ratio tokamak with an aspect ratio of 8 was found to achieve a burn time of 3.5 h at capital cost only approx. 25% greater than that of a moderate aspect ratio design tokamak
Dong, Bo; Zhang, Yun; Ye, Shuangli; Zhou, Yanzhou; He, Zhaoshui; Xie, Shengli
2017-09-01
A dual-channel phase-contrast spectral optical coherence tomography (DPC-SOCT) method is proposed for measuring axial and normal to B-scan off-axial displacements inside weakly scattering translucent materials. By employing a dual-channel observation structure with depth multiplexing, only one shot before and one shot after the object deformation are required for simultaneously measuring the displacements. To validate the method, a DPC-SOCT system was built and axial and normal to B-scan off-axial displacements inside polymer films were measured at 20 frames per second. The results suggest that the method can be used for investigating inner mechanical properties of materials under different loads. In the future, a method for all orthogonal measurement of displacement components will be developed.
Mori, Eiji; Ueta, Takayoshi; Maeda, Takeshi; Yugué, Itaru; Kawano, Osamu; Shiba, Keiichiro
2015-03-01
Axial neck pain after C3-6 laminoplasty has been reported to be significantly lesser than that after C3-7 laminoplasty because of the preservation of the C-7 spinous process and the attachment of nuchal muscles such as the trapezius and rhomboideus minor, which are connected to the scapula. The C-6 spinous process is the second longest spinous process after that of C-7, and it serves as an attachment point for these muscles. The effect of preserving the C-6 spinous process and its muscular attachment, in addition to preservation of the C-7 spinous process, on the prevention of axial neck pain is not well understood. The purpose of the current study was to clarify whether preservation of the paraspinal muscles of the C-6 spinous process reduces postoperative axial neck pain compared to that after using nonpreservation techniques. The authors studied 60 patients who underwent C3-6 double-door laminoplasty for the treatment of cervical spondylotic myelopathy or cervical ossification of the posterior longitudinal ligament; the minimum follow-up period was 1 year. Twenty-five patients underwent a C-6 paraspinal muscle preservation technique, and 35 underwent a C-6 nonpreservation technique. A visual analog scale (VAS) and VAS grading (Grades I-IV) were used to assess axial neck pain 1-3 months after surgery and at the final follow-up examination. Axial neck pain was classified as being 1 of 5 types, and its location was divided into 5 areas. The potential correlation between the C-6/C-7 spinous process length ratio and axial neck pain was examined. The mean VAS scores (± SD) for axial neck pain were comparable between the C6-preservation group and the C6-nonpreservation group in both the early and late postoperative stages (4.1 ± 3.1 vs 4.0 ± 3.2 and 3.8 ± 2.9 vs 3.6 ± 3.0, respectively). The distribution of VAS grades was comparable in the 2 groups in both postoperative stages. Stiffness was the most prevalent complaint in both groups (64.0% and 54
Kroon, Féline P B; van der Burg, Lennart R A; Ramiro, Sofia; Landewé, Robert B M; Buchbinder, Rachelle; Falzon, Louise; van der Heijde, Désirée
2015-07-17
Axial spondyloarthritis (axSpA) comprises ankylosing spondylitis (radiographic axSpA) and non-radiographic (nr-)axSpA and is associated with psoriasis, uveitis and inflammatory bowel disease. Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as first-line drug treatment. To determine the benefits and harms of NSAIDs in axSpA. We searched CENTRAL, MEDLINE and EMBASE to 18 June 2014. Randomised controlled trials (RCTs) or quasi-RCTs of NSAIDs versus placebo or any comparator in adults with axSpA and observational cohort studies studying the long term effect (≥ six months) of NSAIDs on radiographic progression or adverse events (AEs). The main comparions were traditional or COX-2 NSAIDs versus placebo. The major outcomes were pain, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), radiographic progression, number of withdrawals due to AEs and number of serious AEs Two review authors independently selected trials for inclusion, assessed the risk of bias, extracted data and assessed the quality of evidence for major outcomes using GRADE. We included 39 studies (35 RCTs, two quasi-RCTs and two cohort studies); and 29 RCTs and two quasi-RCTs (n = 4356) in quantitative analyses for the comparisons: traditional NSAIDs versus placebo, cyclo-oxygenase-2 (COX-2) versus placebo, COX-2 versus traditional NSAIDs, NSAIDs versus NSAIDs, naproxen versus other NSAIDs, low versus high dose. Most trials were at unclear risk of selection bias (n = 29), although blinding of participants and personnel was adequate in 24 trials. Twenty-five trials had low risk of attrition bias and 29 trials had low risk of reporting bias. Risk of bias in both cohort studies was high for study participation, and low or unclear for all other criteria. No trials in the meta-analyses assessed patients with nr-axSpA.Traditional NSAIDs were more beneficial than placebo at six
Directory of Open Access Journals (Sweden)
Phillip M. Ligrani
1996-01-01
Full Text Available Experimental results are presented which describe the development and structure of flow downstream of a single row of holes with compound angle orientations producing film cooling at high blowing ratios. This film cooling configuration is important because similar arrangements are frequently employed on the first stage of rotating blades of operating gas turbine engines. With this configuration, holes are spaced 6d apart in the spanwise direction, with inclination angles of 24 degrees, and angles of orientation of 50.5 degrees. Blowing ratios range from 1.5 to 4.0 and the ratio of injectant to freestream density is near 1.0. Results show that spanwise averaged adiabatic effectiveness, spanwise-averaged iso-energetic Stanton number ratios, surveys of streamwise mean velocity, and surveys of injectant distributions change by important amounts as the blowing ratio increases. This is due to injectant lift-off from the test surface just downstream of the holes.
SCP2, a major protein component of the axial elements of synaptonemal complexes
Schalk, J.A.C.
1999-01-01
Synaptonemal complexes (SCs) are ladderlike protein structures, which are formed between homologous chromosomes during the prophase of the first meiotic division. SCs consist of two axial elements, one along each chromosome, and transverse filaments (TFs), which connect the axial elements.
Lungfish axial muscle function and the vertebrate water to land transition.
Directory of Open Access Journals (Sweden)
Angela M Horner
Full Text Available The role of axial form and function during the vertebrate water to land transition is poorly understood, in part because patterns of axial movement lack morphological correlates. The few studies available from elongate, semi-aquatic vertebrates suggest that moving on land may be powered simply from modifications of generalized swimming axial motor patterns and kinematics. Lungfish are an ideal group to study the role of axial function in terrestrial locomotion as they are the sister taxon to tetrapods and regularly move on land. Here we use electromyography and high-speed video to test whether lungfish moving on land use axial muscles similar to undulatory swimming or demonstrate novelty. We compared terrestrial lungfish data to data from lungfish swimming in different viscosities as well as to salamander locomotion. The terrestrial locomotion of lungfish involved substantial activity in the trunk muscles but almost no tail activity. Unlike other elongate vertebrates, lungfish moved on land with a standing wave pattern of axial muscle activity that closely resembled the pattern observed in terrestrially locomoting salamanders. The similarity in axial motor pattern in salamanders and lungfish suggests that some aspects of neuromuscular control for the axial movements involved in terrestrial locomotion were present before derived appendicular structures.
Concept design of the axial injection system of type CYCIAE cyclotrons
International Nuclear Information System (INIS)
Xiao Meiqin; Zhang Tianjue; Fan Mingwu
1996-01-01
Beam optics properties of the axial injection system of CYCIAE30 is calculated and compared with operation results to show that the theory and the calculation method used are reasonable. Then, the concept design of the axial injection system of CYCIAE 70 is made and optimization results are obtained
International Nuclear Information System (INIS)
Sun Jinji; Ren Yuan; Fang Jiancheng
2011-01-01
The paper presents a special configuration of passive axial magnetic bearing with segmented Halbach magnetized array in magnetically suspended control moment gyro (MSCMG). Peculiarity of presented passive axial magnetic bearing is its ability to provide angular stiffness so that it can produce gyro moment when it is used in MSCMG. The MSCMG with this passive axial magnetic bearing can efficiently reduce the power loss when it supplies gyro moment compared with the five degrees of freedom (5-DOF) MSCMG. The characteristics of the suspension force and stiffness of the passive axial magnetic bearing are studied using finite element method (FEM). The performance of the presented passive axial magnetic bearing with Halbach magnetized array is verified by a prototyped MSCMG. - Research highlights: → Passive axial magnetic bearing is used to provide angular stiffness. → Passive axial magnetic bearing is based on repulsion. → Layers Halbach magnetized array realizes higher stiffness per bearing volume. → Passive axial magnetic bearing can provide gyro moment in CMG. → Power loss of MSCMG with PMB does not increase when it provides gyro moment.
Indigenous development of a 2 kW RF-excited fast axial flow CO2 ...
Indian Academy of Sciences (India)
RF-excited fast axial flow CO2 lasers in kilowatt regime are presently being used for various new scientific applications in addition to laser material processing because of its versatility and superior beam quality. We have indigenously developed a compact 2 kW RF-excited fast axial flow CO2 laser with moderate beam ...
A benchmark study of procedures for analysis of axial crushing of bulbous bows
DEFF Research Database (Denmark)
Yamada, Yasuhira; Pedersen, Preben Terndrup
2008-01-01
Simplified methods to estimate mean axial crushing forces of plated structures are reviewed and applied to a series of experimental results for axial crushing of large-scale bulbous bow models. Methods based on intersection unit elements such as L-, T- and X-type elements as well as methods based...
Directory of Open Access Journals (Sweden)
Min-Chieh Hsieh
2015-06-01
Conclusion: Compared with the teeth preparation of external axial wall in a single crown, the sighted distance at 30-cm distance in the internal axial wall is 1.5 × wider. More sighted distances are required to prevent undesired undercuts.
Constraining vectors and axial-vectors in walking technicolour by a holographic principle
DEFF Research Database (Denmark)
D. Dietrich, Dennis; Kouvaris, Christoforos
2008-01-01
We use a holographic principle to study the low-energy spectrum of walking technicolour models. In particular, we predict the masses of the axial vectors as well as the decay constants of vectors and axial vectors as functions of the mass of the techni-rho. Given that there are very few...
Cdx and Hox Genes Differentially Regulate Posterior Axial Growth in Mammalian Embryos
Young, Teddy; Rowland, Jennifer Elizabeth; van de Ven, Cesca; Bialecka, Monika; Novoa, Ana; Carapuco, Marta; van Nes, Johan; de Graaff, Wim; Duluc, Isabelle; Freund, Jean-Noel; Beck, Felix; Mallo, Moises; Deschamps, Jacqueline
2009-01-01
Hox and Cdx transcription factors regulate embryonic positional identities. Cdx mutant mice display posterior body truncations of the axial skeleton, neuraxis, and caudal urorectal structures. We show that trunk Hox genes stimulate axial extension, as they can largely rescue these Cdx mutant
Osteoblastomas of the axial skeleton shown by skeletal scanning: case report
International Nuclear Information System (INIS)
Martin, N.L.; Preston, D.F.; Robinson, R.G.
1976-01-01
Two patients with osteoblastoma of the axial skeleton showed intense uptake of 99 /sup m/Tc-polyphosphate and 99 /sup m/Tc-diphosphonate on skeletal scans. Although this lesion is uncommon, it should be included in the differential diagnosis for young patients who show abnormal accumulation of 99 /sup m/Tc-phosphates in the axial skeleton
Cavitation in centrifugal pump with rotating walls of axial inlet device
Moloshnyi, O.; Sotnyk, M.
2017-08-01
The article deals with the analysis of cavitation processes in the flowing part of the double entry centrifugal pump. The analysis is conducted using numerical modeling of the centrifugal pump operating process in the software environment ANSYS CFX. Two models of the axial inlet device is researched. It is shaped by a cylindrical section and diffuser section in front of the impeller, which includes fairing. The walls of the axial inlet device rotate with the same speed as the pump rotor. The numerical experiment is conducted under the condition of the flow rate change and absolute pressure at the inlet. The analysis shows that the pump has the average statistical cavitation performance. The occurrence of the cavitation in the axial inlet device is after narrowing the cross-section of flow channel and at the beginning of the diffuser section. Additional sudden expansion at the outlet of the axial inlet diffuser section does not affect the cavitation characteristics of the impeller, however, improves cavitation characteristics of the axial inlet device. For considered geometric parameters of the axial inlet device the cavitation in the impeller begins earlier than in the axial inlet device. That is, the considered design of the axial inlet device will not be subjected to destruction at the ensuring operation without cavitation in the impeller.
International Nuclear Information System (INIS)
Luyckx, G; Voet, E; De Waele, W; Degrieck, J
2010-01-01
Embedded optical fibre sensors are considered in numerous applications for structural health monitoring purposes. However, since the optical fibre and the host material in which it is embedded, will have different material properties, strain in both materials will not be equal when load is applied. Therefore, the multi-axial strain transfer from the host material to the embedded sensor (optical fibre) has to be considered in detail. In the first part of this paper the strain transfer will be determined using finite element modelling of a circular isotropic glass fibre embedded first in an isotropic host and second in an anisotropic composite material. The strain transfer or relation depends on the mechanical properties of the host material and the sensor (Young's modulus and Poisson's ratio), on the lay-up of the composite material (uni-directional lay-up/cross-ply lay-up) and the position of the sensor in a certain layer. In the second part of the paper the developed strain transfer model will be evaluated for one specific lay-up and sensor type
Xu, Kailiang; Ta, Dean; Cassereau, Didier; Hu, Bo; Wang, Weiqi; Laugier, Pascal; Minonzio, Jean-Gabriel
2016-09-01
Some pioneering studies have shown the clinical feasibility of long bones evaluation using ultrasonic guided waves. Such a strategy is typically designed to determine the dispersion information of the guided modes to infer the elastic and structural characteristics of cortical bone. However, there are still some challenges to extract multimode dispersion curves due to many practical limitations, e.g., high spectral density of modes, limited spectral resolution and poor signal-to-noise ratio. Recently, two representative signal processing methods have been proposed to improve the dispersion curves extraction. The first method is based on singular value decomposition (SVD) with advantages of multi-emitter and multi-receiver configuration for enhanced mode extraction; the second one uses linear Radon transform (LRT) with high-resolution imaging of the dispersion curves. To clarify the pros and cons, a face to face comparison was performed between the two methods. The results suggest that the LRT method is suitable to separate the guided modes at low frequency-thickness-product ( fh) range; for multimode signals in broadband fh range, the SVD-based method shows more robust performances for weak mode enhancement and noise filtering. Different methods are valuable to cover the entire fh range for processing ultrasonic axial transmission signals measured in long cortical bones.
Retinal axial focusing and multi-layer imaging with a liquid crystal adaptive optics camera
International Nuclear Information System (INIS)
Liu Rui-Xue; Zheng Xian-Liang; Li Da-Yu; Hu Li-Fa; Cao Zhao-Liang; Mu Quan-Quan; Xuan Li; Xia Ming-Liang
2014-01-01
With the help of adaptive optics (AO) technology, cellular level imaging of living human retina can be achieved. Aiming to reduce distressing feelings and to avoid potential drug induced diseases, we attempted to image retina with dilated pupil and froze accommodation without drugs. An optimized liquid crystal adaptive optics camera was adopted for retinal imaging. A novel eye stared system was used for stimulating accommodation and fixating imaging area. Illumination sources and imaging camera kept linkage for focusing and imaging different layers. Four subjects with diverse degree of myopia were imaged. Based on the optical properties of the human eye, the eye stared system reduced the defocus to less than the typical ocular depth of focus. In this way, the illumination light can be projected on certain retina layer precisely. Since that the defocus had been compensated by the eye stared system, the adopted 512 × 512 liquid crystal spatial light modulator (LC-SLM) corrector provided the crucial spatial fidelity to fully compensate high-order aberrations. The Strehl ratio of a subject with −8 diopter myopia was improved to 0.78, which was nearly close to diffraction-limited imaging. By finely adjusting the axial displacement of illumination sources and imaging camera, cone photoreceptors, blood vessels and nerve fiber layer were clearly imaged successfully. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Evaporation thermal anslysis of Swallow-tailed Axial-grooved Heat Pipe
Zhang, Renping
2018-03-01
A detailed mathematical model that describes evaporating characteristics through thin liquid film at the evaporator section of swallow-tailed axial-grooved heat pipe was developed. The numerical simulation results about thin film profile, liquid-vapour interface temperature, evaporating rate and heat flux at the evaporating thin film region were given by the current investigation and the effect of superheat on the liquid-vapour interface temperature, evaporating mass rate and heat flux was discussed. Meanwhile, thermal model of the meniscus region at the evaporating section was developed to calculate the rate of heat transfer. The ratio of the heat conduction in the evaporating thin liquid film region and total heat rate were also discussed. It is indicated that the thickness of thin liquid film rises in a nearly linear fashion. The disjoining pressure can be neglected with increasing the liquid film thickness, tends to be negligibly small. The heat transfer rate at the intrinsic meniscus cannot be compared with that of the evaporating liquid film region.
Performance Analysis of CFRP Composite Strips Confined RC Columns under Axial Compression
Directory of Open Access Journals (Sweden)
J. Raja Murugadoss
2015-01-01
Full Text Available In an attempt to mitigate the high cost of FRP composite strengthening, an experimental investigation was carried out that sought to achieve efficient and most favorable FRP strengthening using CFRP composite strips. 50 mm wide CFRP composite strips were used in two different spacings (20 mm and 40 mm to confine columns. The test results of the column confined with smaller spacing (20 mm showed significant restraint of axial deformation of the column and enhanced the strength capacity to a maximum of 99.20% compared to that of reference column. In contrast, the column confined by strips with larger spacing (40 mm failed by crushing of concrete alone, which occurred even before the CFRP strips reached their ultimate strain. In addition, the embodied energy that exists in the CFRP strips could not be utilized effectively. The stress and strength enhancement ratio of this present study was compared with the previous research that has been conducted on columns confined with full wrapping. From the obtained results, it is recommended that CFRP strips with a spacing of 20 mm be used to improve the strength capacity of the RC column; in addition, this wrapping technique provides economic benefits compared to a column confined with full wrapping.
Axial Compression Behavior of a New Type of Prefabricated Concrete Sandwich Wall Panel
Qun, Xie; Shuai, Wang; Chun, Liu
2018-03-01
A novel type of prefabricated concrete sandwich wall panel which could be used as a load-bearing structural element in buildings has been presented in this paper. Compared with the traditional sandwich panels, there are several typical characteristics for this wall system, including core columns confined by spiral stirrup along the cross-section of panel with 600mm spacing, precast foamed concrete block between two structural layers as internal insulation part, and a three-dimensional (3D) steel wire skeleton in each layer which is composed of two vertical steel wire meshes connected by horizontally short steel bar. All steel segments in the panel are automatically prefabricated in factory and then are assembled to form steel system in site. In order to investigate the structural behavior of this wall panel, two full-scale panels have been experimentally studied under axial compressive load. The test results show that the wall panel presents good load-bearing capacity and integral stiffness without out-of-plane flexural failure. Compared to the panel with planar steel wire mesh in concrete layer, the panel with 3D steel wire skeleton presents higher strength and better rigidity even in the condition of same steel ratio in panels which verifies that the 3D steel skeleton could greatly enhance the structural behavior of sandwich panel.
Retinal axial focusing and multi-layer imaging with a liquid crystal adaptive optics camera
Liu, Rui-Xue; Zheng, Xian-Liang; Li, Da-Yu; Xia, Ming-Liang; Hu, Li-Fa; Cao, Zhao-Liang; Mu, Quan-Quan; Xuan, Li
2014-09-01
With the help of adaptive optics (AO) technology, cellular level imaging of living human retina can be achieved. Aiming to reduce distressing feelings and to avoid potential drug induced diseases, we attempted to image retina with dilated pupil and froze accommodation without drugs. An optimized liquid crystal adaptive optics camera was adopted for retinal imaging. A novel eye stared system was used for stimulating accommodation and fixating imaging area. Illumination sources and imaging camera kept linkage for focusing and imaging different layers. Four subjects with diverse degree of myopia were imaged. Based on the optical properties of the human eye, the eye stared system reduced the defocus to less than the typical ocular depth of focus. In this way, the illumination light can be projected on certain retina layer precisely. Since that the defocus had been compensated by the eye stared system, the adopted 512 × 512 liquid crystal spatial light modulator (LC-SLM) corrector provided the crucial spatial fidelity to fully compensate high-order aberrations. The Strehl ratio of a subject with -8 diopter myopia was improved to 0.78, which was nearly close to diffraction-limited imaging. By finely adjusting the axial displacement of illumination sources and imaging camera, cone photoreceptors, blood vessels and nerve fiber layer were clearly imaged successfully.
Flow control in axial fan inlet guide vanes by synthetic jets
Directory of Open Access Journals (Sweden)
Wurst P.
2013-04-01
Full Text Available Tested high pressure axial flow fan with hub/tip ratio of 0.70 and external diameter of 600 mm consisted of inlet guide vanes (IGV, rotor and stator blade rows. Fan peripheral velocity was 47 m/s. Air volume flow rate was changed by turning of rear part of the inlet guide vanes. At turning of 20 deg the flow was separated on the IGV profiles. The synthetic jets were introduced through radial holes in machine casing in the location before flow separation origin. Synthetic jet actuator was designed with the use of a speaker by UT AVCR. Its membrane had diameter of 63 mm. Excitation frequency was chosen in the range of 500 Hz – 700 Hz. Synthetic jets favourably influenced separated flow on the vane profiles in the distance of (5 – 12 mm from the casing surface. The reduction of flow separation area caused in the region near the casing the decrease of the profile loss coefficient approximately by 20%.
RATIO_TOOL - SOFTWARE FOR COMPUTING IMAGE RATIOS
Yates, G. L.
1994-01-01
Geological studies analyze spectral data in order to gain information on surface materials. RATIO_TOOL is an interactive program for viewing and analyzing large multispectral image data sets that have been created by an imaging spectrometer. While the standard approach to classification of multispectral data is to match the spectrum for each input pixel against a library of known mineral spectra, RATIO_TOOL uses ratios of spectral bands in order to spot significant areas of interest within a multispectral image. Each image band can be viewed iteratively, or a selected image band of the data set can be requested and displayed. When the image ratios are computed, the result is displayed as a gray scale image. At this point a histogram option helps in viewing the distribution of values. A thresholding option can then be used to segment the ratio image result into two to four classes. The segmented image is then color coded to indicate threshold classes and displayed alongside the gray scale image. RATIO_TOOL is written in C language for Sun series computers running SunOS 4.0 and later. It requires the XView toolkit and the OpenWindows window manager (version 2.0 or 3.0). The XView toolkit is distributed with Open Windows. A color monitor is also required. The standard distribution medium for RATIO_TOOL is a .25 inch streaming magnetic tape cartridge in UNIX tar format. An electronic copy of the documentation is included on the program media. RATIO_TOOL was developed in 1992 and is a copyrighted work with all copyright vested in NASA. Sun, SunOS, and OpenWindows are trademarks of Sun Microsystems, Inc. UNIX is a registered trademark of AT&T Bell Laboratories.
Topological invariants and the dynamics of an axial vector torsion field
International Nuclear Information System (INIS)
Drechsler, W.
1983-01-01
A generalized throry of gravitation is discussed which is based on a Riemann-Cartan space-time, U 4 , with an axial vector torsion field. Besides Einstein's equations determining the metric of the U 4 a system of nonlinear field equations is established coupling an axial vector source current to the axial vector torsion field. The properties of the solutions of these equations are discussed assuming a London-type condition relating the axial current and torsion field. To characterize the solutions use is made of the Euler and Pontrjagin forms and the associated quadratic curvature invariants for the U 4 space-time. It is found that there exists for a Riemann-Cartan space-time a relation between the zeros of the axial vector torsion field and the singularities of the Pontrjagin invariant, which is analogous to the well-known Hopf relation between the zeros of vector fields and the Euler characteristic. (author)
Three-dimensional axial volume acquisition on meniscal lesions of the knee
Energy Technology Data Exchange (ETDEWEB)
Araki, Yutaka; Ootani, Masatoshi; Furukawa, Tomoaki; Yamamoto, Tadatsuka; Tomoda, Kaname; Tsukaguchi, Isao (Osaka Rosai Hospital, Sakai (Japan)); Mitomo, Masanori
1991-12-01
Axial three-dimensional volume scans obtained by magnetic resonance (MR) imaging were used to evaluate meniscal lesions of the knee in 28 knees of 26 cases. Axial 0.7 mm thin-sliced images with volume scan outlined the overall meniscal appearance for the first time. Axial volume scan was essential to the diagnosis of discoid lateral meniscus because only it could depict the characteristic elongated appearance of discoid lateral meniscus. Radial meniscal tears were depicted only by this technique: conventional sagittal and coronal views could not detect this type of meniscal tear. Volume scan could detect the precise extent of lesions with horizontal meniscal tears and meniscal degeneration. These MR findings obtained by axial volume scans were confirmed by arthroscopy in all cases. We concluded that volume scans were extremely useful in the evaluation of meniscal lesions because they offered axial views that provided much information on menisci located horizontally in the knee. (author).
Roy, Sthitadhi; Kolodrubetz, Michael; Goldman, Nathan; Grushin, Adolfo G.
2018-04-01
In this work, we describe a toolbox to realize and probe synthetic axial gauge fields in engineered Weyl semimetals. These synthetic electromagnetic fields, which are sensitive to the chirality associated with Weyl nodes, emerge due to spatially and temporally dependent shifts of the corresponding Weyl momenta. First, we introduce two realistic models, inspired by recent cold-atom developments, which are particularly suitable for the exploration of these synthetic axial gauge fields. Second, we describe how to realize and measure the effects of such axial fields through center-of-mass observables, based on semiclassical equations of motion and exact numerical simulations. In particular, we suggest realistic protocols to reveal an axial Hall response due to the axial electric field \
Three-dimensional axial volume acquisition on meniscal lesions of the knee
International Nuclear Information System (INIS)
Araki, Yutaka; Ootani, Masatoshi; Furukawa, Tomoaki; Yamamoto, Tadatsuka; Tomoda, Kaname; Tsukaguchi, Isao; Mitomo, Masanori.
1991-01-01
Axial three-dimensional volume scans obtained by magnetic resonance (MR) imaging were used to evaluate meniscal lesions of the knee in 28 knees of 26 cases. Axial 0.7 mm thin-sliced images with volume scan outlined the overall meniscal appearance for the first time. Axial volume scan was essential to the diagnosis of discoid lateral meniscus because only it could depict the characteristic elongated appearance of discoid lateral meniscus. Radial meniscal tears were depicted only by this technique: conventional sagittal and coronal views could not detect this type of meniscal tear. Volume scan could detect the precise extent of lesions with horizontal meniscal tears and meniscal degeneration. These MR findings obtained by axial volume scans were confirmed by arthroscopy in all cases. We concluded that volume scans were extremely useful in the evaluation of meniscal lesions because they offered axial views that provided much information on menisci located horizontally in the knee. (author)
Ezhova, O V; Egorova, E A; Malakhov, V V
2016-05-01
The ultrastructure of the axial organ of Asterias amurensis has been studied The organ is a network of canals of the axial coelom separated by haemocoelic spaces. The axial coelom is lined with two types of monociliary cells: podocytes and musculo-epithelial cells. Podocytes form numerous basal processes adjacent to the basal lamina on the coelomic side. Musculo-epithelial cells form processes running along the basal lamina. Some bundles of these processes wrapped in the basal lamina pass through haemocoelic spaces between neighboring coelomic canals. It is hypothesized that the axial organ serves for filtration of fluid from haemocoelic spaces into the axial coelom cavity, from which urine is excreted through the madreporite to the exterior.
What changed during the axial age: Cognitive styles or reward systems?
Baumard, Nicolas; Hyafil, Alexandre; Boyer, Pascal
2015-01-01
The 'Axial Age' (500-300 BCE) refers to the period during which most of the main religious and spiritual traditions emerged in Eurasian societies. Although the Axial Age has recently been the focus of increasing interest,(1-5) its existence is still very much in dispute. The main reason for questioning the existence of the Axial Age is that its nature, as well as its spatial and temporal boundaries, remain very much unclear. The standard approach to the Axial Age defines it as a change of cognitive style, from a narrative and analogical style to a more analytical and reflective style, probably due to the increasing use of external memory tools. Our recent research suggests an alternative hypothesis, namely a change in reward orientation, from a short-term materialistic orientation to a long-term spiritual one.(6) Here, we briefly discuss these 2 alternative definitions of the Axial Age.
High ratio recirculating gas compressor
Weinbrecht, J.F.
1989-08-22
A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor. 10 figs.
Perceka, Wisena; Liao, Wen-Cheng; Wang, Yo-de
2016-01-01
Addition of steel fibers to high strength concrete (HSC) improves its post-peak behavior and energy absorbing capability, which can be described well in term of toughness. This paper attempts to obtain both analytically and experimentally the efficiency of steel fibers in HSC columns with hybrid confinement of transverse reinforcement and steel fibers. Toughness ratio (TR) to quantify the confinement efficiency of HSC columns with hybrid confinement is proposed through a regression analysis by involving sixty-nine TRs of HSC without steel fibers and twenty-seven TRs of HSC with hybrid of transverse reinforcement and steel fibers. The proposed TR equation was further verified by compression tests of seventeen HSC columns conducted in this study, where twelve specimens were reinforced by high strength rebars in longitudinal and transverse directions. The results show that the efficiency of steel fibers in concrete depends on transverse reinforcement spacing, where the steel fibers are more effective if the spacing transverse reinforcement becomes larger in the range of 0.25–1 effective depth of the section column. Furthermore, the axial load–strain curves were developed by employing finite element software (OpenSees) for simulating the response of the structural system. Comparisons between numerical and experimental axial load–strain curves were carried out. PMID:28773391
Development of the Process Index for NiCrAlY Coatings with the Mettech Axial III™ System
Gao, Feng; Yang, Qi; Huang, Xiao; Liu, Rong
2013-03-01
NiCrAlY coatings were deposited using the Mettech Axial III™ plasma spray system. The microstructural features of the coatings, such as the porosity, crack, un-melted particle, and oxide content, were analyzed to investigate the effects of the spray process parameters on these features. Two Taguchi arrays were used to examine the effects of the spray process parameters such as powder size, ratio of (H2 + N2) gas flow over total gas flow, current, spray-gun nozzle size, and spray distance, on the microstructural features of the coatings. The results from statistical analysis are used to create regression equations to predict the microstructural features of the coatings. In the regression equations, a process index (PI) is used as a complex variable incorporating a number of process parameters. The results from an additional set of experiments are used to verify the validity of the regression equations. It has been demonstrated that the equations correlate well with the results from the subsequent set of experiments. It is concluded from this study that the PI can be used to categorize coating qualities with respect to the extent of crack, porosity, unmelted particle, and oxide content in the coating. These equations can also serve as an initial step in developing process parameters by means of the Mettech Axial III™ System.
Safaei, B; Naseradinmousavi, P; Rahmani, A
2016-04-01
In the present paper, an analytical solution based on a molecular mechanics model is developed to evaluate the elastic critical axial buckling strain of chiral multi-walled carbon nanotubes (MWCNTs). To this end, the total potential energy of the system is calculated with the consideration of the both bond stretching and bond angular variations. Density functional theory (DFT) in the form of generalized gradient approximation (GGA) is implemented to evaluate force constants used in the molecular mechanics model. After that, based on the principle of molecular mechanics, explicit expressions are proposed to obtain elastic surface Young's modulus and Poisson's ratio of the single-walled carbon nanotubes corresponding to different types of chirality. Selected numerical results are presented to indicate the influence of the type of chirality, tube diameter, and number of tube walls in detailed. An excellent agreement is found between the present numerical results and those found in the literature which confirms the validity as well as the accuracy of the present closed-form solution. It is found that the value of critical axial buckling strain exhibit significant dependency on the type of chirality and number of tube walls. Copyright © 2016. Published by Elsevier Inc.
Hagihara, Seiya; Miyazaki, Noriyuki
1998-05-01
Cylindrical shells are utilized as structural elements of nuclear power plants, heat exchangers or pressure vessels, which are operated under elevated temperature. Creep buckling is one of the failure modes of structures at elevated temperature. In some experiments conducted by other authors, axially compressive cylindrical shells with a large ratio of radius to thickness were observed to buckle with circumferential waves. It is observed that the circumferential waves occur due to bifurcation buckling. But, the critical time and the minimum loading for bifurcation buckling obtained from calculations of finite element analyses are not in very good agreement with those of the experiments. One of the reasons for the disagreement is considered to be that the creep constitutive equations employed in many previous analyses represent the steady creep. The creep phenomena usually have primary creep period, steady creep one and tertiary creep one. A creep strain - time relation through the three periods can be simulated by using a constitutive equation based on creep damage mechanics. In the present analysis, we analyzed the bifurcation creep buckling of circular cylindrical shells subjected to axial compression by the use of the finite element method taking account of the creep damage mechanics proposeol by of Kachanov-Rabotonov.
Directory of Open Access Journals (Sweden)
Achillopoulou Dimitra
2014-12-01
Full Text Available The study deals with the investigation of the effect of casting deficiencies- both experimentally and analytically on axial yield load or reinforced concrete columns. It includes 6 specimens of square section (150x150x500 mm of 24.37 MPa nominal concrete strength with 4 longitudinal steel bars of 8 mm (500 MPa nominal strength with confinement ratio ωc=0.15. Through casting procedure the necessary provisions defined by International Standards were not applied strictly in order to create construction deficiencies. These deficiencies are quantified geometrically without the use of expensive and expertise non-destructive methods and their effect on the axial load capacity of the concrete columns is calibrated trough a novel and simplified prediction model extracted by an experimental and analytical investigation that included 6 specimens. It is concluded that: a even with suitable repair, load reduction up to 22% is the outcome of the initial construction damage presence, b the lower dispersion is noted for the section damage index proposed, c extended damage alters the failure mode to brittle accompanied with longitudinal bars buckling, d the proposed model presents more than satisfying results to the load capacity prediction of repaired columns.
Penetration of Multiple, Axially Offset, Disk-Shaped Penetrators
National Research Council Canada - National Science Library
Kimsey, Kent
2001-01-01
The terminal ballistic performance of high-velocity, low length-to-diameter (L/D) ratio projectiles impacting steel targets has been a topic of considerable interest in penetration mechanics to evaluate the efficacy of segmented projectiles...
Dynamic Stability of Euler Beams under Axial Unsteady Wind Force
Directory of Open Access Journals (Sweden)
You-Qin Huang
2014-01-01
Full Text Available Dynamic instability of beams in complex structures caused by unsteady wind load has occurred more frequently. However, studies on the parametric resonance of beams are generally limited to harmonic loads, while arbitrary dynamic load is rarely involved. The critical frequency equation for simply supported Euler beams with uniform section under arbitrary axial dynamic forces is firstly derived in this paper based on the Mathieu-Hill equation. Dynamic instability regions with high precision are then calculated by a presented eigenvalue method. Further, the dynamically unstable state of beams under the wind force with any mean or fluctuating component is determined by load normalization, and the wind-induced parametric resonant response is computed by the Runge-Kutta approach. Finally, a measured wind load time-history is input into the dynamic system to indicate that the proposed methods are effective. This study presents a new method to determine the wind-induced dynamic stability of Euler beams. The beam would become dynamically unstable provided that the parametric point, denoting the relation between load properties and structural frequency, is located in the instability region, no matter whether the wind load component is large or not.
Axial acoustic radiation force on a sphere in Gaussian field
Energy Technology Data Exchange (ETDEWEB)
Wu, Rongrong; Liu, Xiaozhou, E-mail: xzliu@nju.edu.cn; Gong, Xiufen [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)
2015-10-28
Based on the finite series method, the acoustical radiation force resulting from a Gaussian beam incident on a spherical object is investigated analytically. When the position of the particles deviating from the center of the beam, the Gaussian beam is expanded as a spherical function at the center of the particles and the expanded coefficients of the Gaussian beam is calculated. The analytical expression of the acoustic radiation force on spherical particles deviating from the Gaussian beam center is deduced. The acoustic radiation force affected by the acoustic frequency and the offset distance from the Gaussian beam center is investigated. Results have been presented for Gaussian beams with different wavelengths and it has been shown that the interaction of a Gaussian beam with a sphere can result in attractive axial force under specific operational conditions. Results indicate the capability of manipulating and separating spherical spheres based on their mechanical and acoustical properties, the results provided here may provide a theoretical basis for development of single-beam acoustical tweezers.
Investigation of unsteady flow in axial turbine stage
Directory of Open Access Journals (Sweden)
Němec Martin
2012-04-01
Full Text Available The never ending process to increase the efficiency of turbine stages introduced an idea to create an axial turbine stage test rig as part of closed loop transonic wind tunnel at Vyzkumny a zkusebni letecky ustav (VZLU. Studying of unsteady flow field behaviours in turbine stages is nowadays essential in the development process. Therefore, the test rig was designed with focusing on possibility of detailed studying of unsteady flow fields in turbine stages. New methodologies and new instrumentations were developed at VZLU and successfully integrated to gain valuable information from experiments with turbine stages. Two different turbine stages were tested during the facility introduction process. The measurement of these two models demonstrated how flexible the test rig is. One of them was an enlarged model of small gas turbine stage. The other was scaled-down model of stage of intermediate-pressure steam turbine. The external characteristics of both models were acquired during experiments as well as the detailed unsteady flow field measurement. Turbine stages were tested in various regimes in order to check the capabilities of the facility, methodology and instrumentation together. The paper presents results of unsteady flow field investigation in the enlarged turbine stage with unshrouded rotor. The interaction of structures developed in a stator with the rotor flow field is depicted and the influence of turbine load on evolution of secondary flows in rotor is analysed.
A parametric study of axial segregation in a rotating cylinder.
Energy Technology Data Exchange (ETDEWEB)
Bielenberg, J. R. (James R.); Gladysz, G. M. (Gary M.); Graham, Alan L.
2004-01-01
When a cylindrical container, partially filled with a binary granular mixture of particles that differ in size or density, is rotated around its axis, a spontaneous segregation of the two granular components may occur. In order to better understand this phenomena, we have carried out an experimental study probing the effect of average particle size and relative size difference between particles on the onset of segregation. The experimental study is followed by a novel scaling analysis that relates the deterministic, convective driving force for particle segregation to the randomizing diffusional driving force present in these systems through the definition of an axial granular Peclet number. This Peclet number based approach will forgo some of the difficulties inherent in full-scale dynamic simulations, but will still allow us to determine the effects of system parameters on the final steady-state that is achieved. Values of this granular Peclet number are shown to successfully correlate with segregation behavior in the present experiment results, as well as in comparable results present in the literature.
Complementary medicine for axial spondyloarthritis: is there any scientific evidence?
Danve, Abhijeet; Deodhar, Atul
2018-04-09
Majority of patients with axial spondyloarthritis (axSpA) report use of complementary and alternative medicine (CAM) therapies before and even after the diagnosis, due to perceived efficacy and wide-spread belief that these modalities lack side effects. In this review, we describe the available scientific evidence for the CAM therapies in axSpA. Clinical trials of the CAM therapies in axSpA are generally hampered by small sample size, short duration, difficulties in blinding, lack of control groups and strong placebo effect. Nonetheless, exercise programs like Pilates and mind-body techniques such as Tai Chi may have favorable effect on the disease activity and function. Although not yet confirmed, the modulation of the microbiome with the help of probiotics or fecal transplant has face validity given the evolving scientific rationale. Diet has only limited role in the management of axSpA. Deep tissue massage, omega-3 fatty acids and Stanger bath were found to be useful in small studies. CAM therapies are not always entirely well tolerated, particularly the manipulative techniques like chiropractic and Tui-na in patients with advanced disease and osteoporosis. There are no trials of yoga in axSpA despite the wider acceptance and use of yoga as an effective mind-body technique. Larger and better quality clinical trials of CAM therapies are needed to confirm their efficacy and safety in the management of axSpA and to include them in the 'mainstream' medicine.
Conservative management of extra-axial hematomas diagnosed by CT
International Nuclear Information System (INIS)
Muszynski, C.A.; Hayman, L.A.; Weingarten, K.; Prow, H.W.; Cole, J.W.; Contant, C.F.
1999-01-01
Our purpose was to assess the role of serial CT in recently traumatized patients with clinically stable extra-axial intracranial hematomas (EACH) and a midline shift of less than 0.5 cm. A retrospective review of 91 imaging studies in 41 patients (with 45 EACH) was done to assess the time between trauma and CT; the presence and type of skull fracture; the volume, type, and location of the EACH; the presence of associated edema and/or contusion. Over a 19-day follow-up, 11 % of the dense EACH increased in volume and 27 % decreased. An adjacent skull fracture was seen most frequently in patients with a decrease in EACH volume. Clinical data remain the key to determining the need for neurosurgical intervention in patients with EACH. Follow-up CT afforded no data which altered the medical management of these patients. However, it may be said to have alerted the clinician to an increase in the size of the EACH in 11 % of cases, which could mandate close observation of this group. (orig.)
Military boot attenuates axial loading to the lower leg.
Yoganandan, Narayan; Schlick, Michael; Arun, Mike W J; Pintar, Frank A
2014-01-01
Biomechanical tests to understand injury mechanisms and derive injury tolerance information using Post-Mortem Human Subjects (PMHS) have not used foot protection and they have primarily focused on civilian environments such as automotive and athletic- and sports-related events. As military personnel use boots, tests with the boot are required to understand their effect on attenuating lower leg loads. The purpose of this study was therefore, to determine the modulation of human lower leg kinematics with boot compressions and share of the force absorbed by the boot from underbody blast loading. Axial impacts were delivered to the Hybrid III dummy lower leg in the neutral position. The dummy leg was instrumented with its internal upper and lower tibia load cells, and in addition, a knee load cell was attached to the proximal end. Tests were conducted at 4.4 to 8.9 m/s, with and without boots, and repeat tests were done. Morphologies of the force-time responses were similar at the three load cell locations and for all input combinations and booted and unbooted conditions. However, booted tests resulted in considerably lower maximum forces (approximately two-third reduction) than unbooted tests. These results clearly show that boots can absorb a considerable share of the impact energy and decrease impact loads transmitted to the lower leg under vertical loading, thus necessitating the generation of tolerance data using PMHS for this environment.
Numerical optimisation of an axial turbine; Numerische Optimierung einer Axialturbine
Energy Technology Data Exchange (ETDEWEB)
Welzel, B.
1998-12-31
The author presents a method for automatic shape optimisation of components with internal or external flow. The method combines a program for numerical calculation of frictional turbulent flow with an optimisation algorithm. Algorithms are a simplex search strategy and an evolution strategy. The shape of the component to be optimized is variable due to shape parameters modified by the algorithm. For each shape, a flow calculation is carried out on whose basis a functional value like performance, loss, lift or resistivity is calculated. For validation, the optimisation method is used in simple examples with known solutions. It is applied. It is applied to the components of a slow-running axial turbine. Components with accelerated and delayed rotationally symmetric flow and 2D blade profiles are optimized. [Deutsch] Es wird eine Methode zur automatischen Formoptimierung durchstroemter oder umstroemter Bauteile vorgestellt. Diese koppelt ein Programm zur numerischen Berechnung reibungsbehafteter turbulenter Stroemungen mit einem Optimierungsalgorithmus. Dabei kommen als Algorithmen eine Simplex-Suchstrategie und eine Evolutionsstrategie zum Einsatz. Die Form des zu optimierenden Koerpers ist durch Formparameter, die vom Algorithmus veraendert werden, variabel. Fuer jede Form wird eine Stroemungsberechnung durchgefuehrt und mit dieser ein Funktionswert wie Wirkungsgrad, Verlust, Auftrieb oder Widerstandskraft berechnet. Die Optimierungsmethode wird zur Validierung in einfachen Beispielen mit bekannter Loesung eingesetzt. Zur Anwendung kommt sie in den einzelnen Komponenten einer langsamlaeufigen Axialturbine. Es werden Bauteile mit beschleunigter und verzoegerter rotationssymmetrischer Stroemung und 2D-Schaufelprofile optimiert. (orig.)
Meissner effect for axially symmetric charged black holes
Gürlebeck, Norman; Scholtz, Martin
2018-04-01
In our previous work [N. Gürlebeck and M. Scholtz, Phys. Rev. D 95, 064010 (2017), 10.1103/PhysRevD.95.064010], we have shown that electric and magnetic fields are expelled from the horizons of extremal, stationary and axially symmetric uncharged black holes; this is called the Meissner effect for black holes. Here, we generalize this result in several directions. First, we allow that the black hole carries charge, which requires a generalization of the definition of the Meissner effect. Next, we introduce the notion of almost isolated horizons, which is weaker than the usual notion of isolated horizons, since the geometry of the former is not necessarily completely time independent. Moreover, we allow the horizon to be pierced by strings, thereby violating the usual assumption on the spherical topology made in the definition of the weakly isolated horizon. Finally, we spell out in detail all assumptions entering the proof and show that the Meissner effect is an inherent property of black holes even in full nonlinear theory.
Axial focusing of energy from a hypervelocity impact on earth
International Nuclear Information System (INIS)
Boslough, M.B.; Chael, E.P.; Trucano, T.G.; Crawford, D.A.
1994-01-01
We have performed computational simulations to determine how energy from a large hypervelocity impact on the Earth's surface would couple to its interior. Because of the first-order axial symmetry of both the impact energy source and the stress-wave velocity structure of the Earth, a disproportionate amount of energy is dissipated along the axis defined by the impact point and its antipode (point opposite the impact). For a symmetric and homogeneous Earth model, all the impact energy that is radiated as seismic waves into the Earth at a given takeoff angle (ray parameter), independent of azimuthal direction, is refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Material on or near the axis of symmetry experiences more strain cycles with much greater amplitude than elsewhere, and therefore experiences more irreversible heating. The focusing is most intense in the upper mantle, within the asthenosphere, where seismic energy is most effectively converted to heat. For a sufficiently energetic impact, this mechanism might generate enough local heating to create an isostatic instability leading to uplift, possibly resulting in rifting, volcanism, or other rearrangement of the interior dynamics of the planet. These simulations demonstrate how hypervelocity impact energy can be transported to the Earth's interior, supporting the possibility of a causal link between large impacts on Earth and major internally-driven geophysical processes
Axial-equatorial isomerism and semiexperimental equilibrium structures of fluorocyclohexane.
Juanes, Marcos; Vogt, Natalja; Demaison, Jean; León, Iker; Lesarri, Alberto; Rudolph, Heinz Dieter
2017-11-08
An experimental-computational methodology combining rotational data, high-level ab initio calculations and predicate least-squares fitting is applied to the axial-equatorial isomerism and semiexperimental equilibrium structure determination of fluorocyclohexane. New supersonic-jet microwave measurements of the rotational spectra of the two molecular conformations, together with all 13 C isotopologues of both isomeric forms are reported. Equilibrium rotational constants are obtained from the ground-state rotational constants corrected for vibration-rotation interactions and electronic contributions. Equilibrium structures were determined by the mixed estimation (ME) method. Different computational methods were tested for the evaluation of predicate values of the structural parameters, and a computationally effective procedure for estimating reliable dihedral angles is proposed. Structural parameters were fitted concurrently to predicate parameters and moments of inertia, affected with appropriate uncertainties. The new structures of the title compound are regarded as accurate to 0.001 Å and 0.2°, illustrating the advantages of this methodology. Structural comparisons are offered with the cyclohexane prototype, revealing subtle substituent effects. For comparison purposes the equilibrium structures for the two fluorocyclohexane isomers and cyclohexanone are computed from high-level ab initio theory with inclusion of adjustments for basis set dependence and correlation of the core electrons.
Negative particle planar and axial channeling and channeling collimation
Energy Technology Data Exchange (ETDEWEB)
Carrigan, Richard A., Jr.; /Fermilab
2009-12-01
While information exists on high energy negative particle channeling there has been little study of the challenges of negative particle bending and channeling collimation. Partly this is because negative dechanneling lengths are relatively much shorter. Electrons are not particularly useful for investigating negative particle channeling effects because their material interactions are dominated by channeling radiation. Another important factor is that the current central challenge in channeling collimation is the proton-proton Large Hadron Collider (LHC) where both beams are positive. On the other hand in the future the collimation question might reemerge for electon-positron or muon colliders. Dechanneling lengths increase at higher energies so that part of the negative particle experimental challenge diminishes. In the article different approaches to determining negative dechanneling lengths are reviewed. The more complicated case for axial channeling is also discussed. Muon channeling as a tool to investigate dechanneling is also discussed. While it is now possible to study muon channeling it will probably not illuminate the study of negative dechanneling.
Morphological study of the axial view of the cervical spinal cord by MR images
International Nuclear Information System (INIS)
Suzuki, Masahiro; Shimamura, Tadashi
1994-01-01
To investigate the morphological changes in the cervical spinal cord in patients with cervical myelopathy, we examined the axial anatomy of the cervical spinal cord and the spinal canal using MRI and CT scans. This study involved 35 patients (mean age=56.8) with cervical myelopathy and 118 adult normal volunteers (mean age=48.1) as controls. The transverse area of the spinal cord was measured on MR images (T 1 images), while the transverse area of the spinal canal was measured on CT. In normal subjects, the transverse area, the sagittal diameter, and the coronal diameter of the spinal cord showed a significant positive correlation with body height, and a significant negative correlation with age. No significant difference was identified between males and females. The transverse area, the sagittal diameter, the coronal diameter, and the ratio of the sagittal/coronal diameter of the spinal cord and the spinal canal showed significant positive correlations among each other in normal subjects, but no significant correlation was noted in the patients with cervical myelopathy. These was no significant difference between the normal subjects and the patients in the transverse area or in the ratio of the sagittal/coronal diameter of the spinal cord at the levels without cord compression. However, the transverse area of the spinal canal in the patients with myelopathy was significantly smaller than that of normal subjects. In conclusion, a poor or no correlation between the size of the spinal cord and the spinal canal is a frequent finding in patients with myelopathy. Furthermore, this study suggests that patients with myelopathy present a narrow spinal canal more frequently than do normal subjects. (author)
Eder, Wolfgang; Hohenegger, Johann; Kinoshita, Shunichi; Wöger, Julia; Briguglio, Antonino
2016-04-01
The cosmopolite foraminifer Heterostegina depressa has been a target of studies, describing its internal and external morphology, ecology and biology. During the last decades many researcher concentrated on test morphology and described its maturoevolute shape. Furthermore, a continuously increasing trend of test flattening along water depth has been described multiple times. However, the most common measurements, such as the thickness/diameter ratio, are too dependent on individual size to pose as an accurate tool. /newline Therefore a growth invariant character has been used to describe the change of thickness through the ontogeny of H. depressa. To compute this, the thickness at the half-radius, the so-called mediolateral thickness, of five whorls has been measured in 127 axial section of H. depressa. Based on this the ontogenetic change in thickness has been computed for specimens from different depth intervals of the slope of Sesoko-Jima, NW-Okinawa. In addition, this has been compared with the actual thickness and the corresponding radii at the same measuring points. The latter describes how thickness would change according to the thickness/diameter ratio./newline Hence, our analysis clearly quantifies a continuous transition of individuals with thicker central parts to individuals with flatter central parts along the water depth gradient. This is most likely controlled by light intensity, since photosymbionts (diatoms) of H. depressa are most active at low irradiation levels. Thus, shallower specimens grow thicker tests to reduce light penetration, while deeper specimens increase their surface to reach a better light exposure. Due to its broad water depth distribution H. depressa is a perfect model species to calibrate test flattening as bathymetric signal for fossil assemblages. Since similar ecological constraints are assumed for fossil nummulitid taxa, useful palaeobathymetric information might be gathered from studying test flattening in extinct species
Khuyagbaatar, Batbayar; Kim, Kyungsoo; Park, Won Man; Kim, Yoon Hyuk
2015-12-01
There are few studies focusing on the prediction of stress distribution according to the types of ossification of the posterior longitudinal ligament, which can be fundamental information associated with clinical aspects such as the relationship between stress level and neurological symptom severity. In this study, the influence of sagittal and axial types of ossification of the posterior longitudinal ligament on mechanical stress in the cervical spinal cord was investigated. A three-dimensional finite element model of the cervical spine with spinal cord was developed and validated. The von Mises stresses in the cord and the reduction in cross-sectional areas and volume of the cord were investigated for various axial and sagittal types according to the occupying ratio of ossification of the posterior longitudinal ligament in the spinal canal. The influence of axial type was less than that of the sagittal type, even though the central type showed higher maximum stresses in the cord, especially for the continuous type. With a 60% occupying ratio of ossification of the posterior longitudinal ligament, the maximum stress was significantly high and the cross-sectional area of the spinal cord was reduced by more than 30% of the intact area regardless of sagittal or axial types. Finally, a higher level of sagittal extension would increase the peak cord tissue stress, which would be related to the neurological dysfunction and tissue damage. Quantitative investigation of biomechanical characteristics such as mechanical stress may provide fundamental information for pre-operative planning of treatment for ossification of the posterior longitudinal ligament. Copyright © 2015 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Gauri D. Bajju
2013-01-01
Full Text Available Reaction of 5,10,15,20-meso-tetra(p-chlorophenylporphyrin[H2(p-Clpp] with zinc(IIacetate(Zn(OAc2 and phenols results in the formation of corresponding axially ligated zinc(II-meso-tetra(p-chlorophenylporphyrin (X-Zn-t(p-ClPP (X = phenolates and pyridinates. The four-coordinated zinc porphyrin accepts one axial ligand in 1 : 1 molar ratio to form five-coordinated complex, which is purified by column chromatography and characterized by IR spectra, 1H NMR, electronic absorption spectra, elemental analysis, mass spectroscopy, and TGA/DTA studies. IR spectra confirms the appearance of Zn– at 500–400 cm−1, Zn– at 650–570 cm−1 and Zn–O at 650–350 cm−1. 1H NMR spectra show that the protons of the Phenolic ring axially attached to the central metal ion are merged with the protons of the tetraphenyl rings of the porphyrin moiety. Absorption spectra reveal that complexes are accompanied by blue shift (hypsochromic shift for phenolates and red shift (bathchromic shift for pyridinates in comparison with the basic Zporphyrin emission bands. Mass Spectra determine the m/z ratio. The percentage of each element is confirmed by elemental analysis. According to the thermal studies, the complexes have a higher thermal stability and the decomposition temperature of these complexes depends on the axial ligation. The invitro antifungal activity of the complexes synthesized above had been done by disc diffusion method against the pathogen “Fusarium spp.,” which shows that with the increase in the concentration of the complexes, the colony diameter decreases and hence percent inhibition increases.
Shape Manifestation of Respiration in the Axial System
Directory of Open Access Journals (Sweden)
Eliška Slawiková
2014-07-01
Full Text Available Shape Manifestation of Respiration in the Axial System The aim of the study was to evaluate the effect of respiration on the shape changes of the axial system. Our approach focuses more on the analysis of respiratory function and their implementation within the complex axial system – the trunk. The results of this pilot study will use as evidence for further study of relationship between respiration and physiotherapy. Now we are looking for an answer to the question, at what level of the human body reflected the influence of respiration and its use in physiotherapy. This pilot study was attended by two women and one man aged 25–40 years, who were not selected for the study according to predetermined conditions. The same characteristic features of all three prarticipants were sedentary job connected with excessive mental strain, occasional low back pain (usually after a long sitting and the absence of acute or chronic respiratory diseases. Another common feature of the participants was the absence of structural changes in the spine. During the experiment was monitored maximum inhalation and maximum exhalation, and respiratory maneuver Kapalabhati, often used as one of the basic yoga breathing exercises. To detect trunk movement during the respiratory maneuver, we opted for a Qualysis – 3D torso topography. At the same time spirometer panned changes in volume over time, both exhaled and inhaled air. The purpose of this study was to assess symptoms and implementation of respiratory maneuvers in the axial system, particularly the chest and abdominal area. During the experiment, we followed the differences in reaction of the chest and abdomen in respiratory maneuver in the direction vertical, antero-posterior and lateral. The difference in these indicators at different phases of the respiratory maneuver confirms our assumption of the possibility of influencing the selected folders axial system through appropriately selected respiratory maneuver
Xia, Rongmin; Thittai, Arun K
2014-03-01
Axial strain elastograms (ASEs) have been found to help visualize sonographically invisible thermal lesions. However, in most studies involving high-intensity focused ultrasound (HIFU)-induced thermal lesions, elastography imaging was performed separately later, after the lesion was formed. In this article, the feasibility of monitoring, in real time, tissue elasticity variation during HIFU treatment and immediately thereafter is explored using quasi-static elastography. Further, in addition to ASEs, we also explore the use of simultaneously acquired axial-shear strain elastograms (ASSEs) for HIFU lesion visualization. Experiments were performed on commercial porcine liver samples in vitro. The HIFU experiments were conducted at two applied acoustic power settings, 35 and 20 W. The experimental setup allowed us to interrupt the HIFU pulse momentarily several different times during treatment to perform elastographic compression and data acquisition. At the end of the experiments, the samples were cut along the imaging plane and photographed to compare size and location of the formed lesion with those visualized on ASEs and ASSEs. Single-lesion and multiple-lesion experiments were performed to assess the contribution of ASEs and ASSEs to lesion visualization and treatment monitoring tasks. At both power settings, ASEs and ASSEs provided accurate location information during HIFU treatment. At the low-power setting case, ASEs and ASSEs provide accurate lesion size in real-time monitoring. Lesion appearance in ASEs and ASSEs was affected by the cavitation bubbles produced at the high-power setting. The results further indicate that the cavitation bubbles influence lesion appearance more in ASEs than in ASSEs. Both ASEs and ASSEs provided accurate size information after a waiting period that allowed the cavitation bubbles to disappear. The results indicate that ASSEs not only improve lesion visualization and size measurement of a single lesion, but, under certain
Updated thinking on positivity ratios.
Fredrickson, Barbara L
2013-12-01
This article presents my response to the article by Brown, Sokal, and Friedman (2013), which critically examined Losada's conceptual and mathematical work (as presented in Losada, 1999; Losada & Heaphy, 2004; and Fredrickson & Losada; 2005) and concluded that mathematical claims for a critical tipping point positivity ratio are unfounded. In the present article, I draw recent empirical evidence together to support the continued value of computing and seeking to elevate positivity ratios. I also underscore the necessity of modeling nonlinear effects of positivity ratios and, more generally, the value of systems science approaches within affective science and positive psychology. Even when scrubbed of Losada's now-questioned mathematical modeling, ample evidence continues to support the conclusion that, within bounds, higher positivity ratios are predictive of flourishing mental health and other beneficial outcomes. PsycINFO Database Record (c) 2013 APA, all rights reserved.
An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy
Kalluri, Sreeramesh; Bonacuse, Peter J.
2010-01-01
Cumulative fatigue under axial and torsional loading conditions can include both load-order (higMow and low/high) as well as load-type sequence (axial/torsional and torsional/axial) effects. Previously reported experimental studies on a cobalt-base superalloy, Haynes 188 at 538 C, addressed these effects. These studies characterized the cumulative axial and torsional fatigue behavior under high amplitude followed by low amplitude (Kalluri, S. and Bonacuse, P. J., "Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequance Effects," in Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387, S. Kalluri, and P. J. Bonacuse, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 281-301) and low amplitude followed by high amplitude (Bonacuse, P. and Kalluri, S. "Sequenced Axial and Torsional Cumulative Fatigue: Low Amplitude Followed by High Amplitude Loading," Biaxial/Multiaxial Fatigue and Fracture, ESIS Publication 31, A. Carpinteri, M. De Freitas, and A. Spagnoli, Eds., Elsevier, New York, 2003, pp. 165-182) conditions. In both studies, experiments with the following four load-type sequences were performed: (a) axial/axial, (b) torsional/torsional, (c) axial/torsional, and (d) torsional/axial. In this paper, the cumulative axial and torsional fatigue data generated in the two previous studies are combined to generate a comprehensive cumulative fatigue database on both the load-order and load-type sequence effects. This comprehensive database is used to examine applicability of the Palmgren-langer-Miner linear damage rule and a nonlinear damage curve approach for Haynes 188 subjected to the load-order and load-type sequencing described above. Summations of life fractions from the experiments are compared to the predictions from both the linear and nonlinear cumulative fatigue damage approaches. The significance of load-order versus load-type sequence effects for axial and torsional loading conditions
Directory of Open Access Journals (Sweden)
Yubo Tao
2016-07-01
Full Text Available Woodceramics were fabricated in a vacuum through carbonization of wood powder impregnated with phenol formaldehyde (PF resin. The effects of carbonization temperature and mass ratio of wood/resin on electromagnetic interference (EMI shielding effectiveness (SE and morphology of woodceramics were explored. The PF resin made wood cell walls have the characteristics of glassy carbon. Wood axial tracheid and ray cells were filled with more glassy carbon by increasing addition of PF resin. Moreover, the increase of carbonization temperature was beneficial to improving SE. Woodceramics (mass ratio 1:1 obtained at 1000 °C presented a medium SE level between 30 MHz and 1.5 GHz.
International Nuclear Information System (INIS)
Patil, A.-A.
1986-01-01
A simple technique for marking functional neurosurgery target on computed tomography (CT) axial image is described. This permits the use of standard axial image for computed tomography (CT) stereotaxis in functional neurosurgery. (Author)
Study on an Axial Flow Hydraulic Turbine with Collection Device
Directory of Open Access Journals (Sweden)
Yasuyuki Nishi
2014-01-01
Full Text Available We propose a new type of portable hydraulic turbine that uses the kinetic energy of flow in open channels. The turbine comprises a runner with an appended collection device that includes a diffuser section in an attempt to improve the output by catching and accelerating the flow. With such turbines, the performance of the collection device, and a composite body comprising the runner and collection device were studied using numerical analysis. Among four stand-alone collection devices, the inlet velocity ratio was most improved by the collection device featuring an inlet nozzle and brim. The inlet velocity ratio of the composite body was significantly lower than that of the stand-alone collection device, owing to the resistance of the runner itself, the decreased diffuser pressure recovery coefficient, and the increased backpressure coefficient. However, at the maximum output tip speed ratio, the inlet velocity ratio and the loading coefficient were approximately 31% and 22% higher, respectively, for the composite body than for the isolated runner. In particular, the input power coefficient significantly increased (by approximately 2.76 times owing to the increase in the inlet velocity ratio. Verification tests were also conducted in a real canal to establish the actual effectiveness of the turbine.
International Nuclear Information System (INIS)
Watanabe, Masaki; Kiryu, Tohru
2011-01-01
The measurement of axial length and the evaluation of three dimensional (3D) form of an eye are essential to evaluate the mechanism of myopia progression. We propose a method of automatic measurement of axial length including adjustment of the pulse sequence of short-term scan which could suppress influence of eyeblink, using a magnetic resonance imaging (MRI) which acquires 3D images noninvasively. Acquiring T 2 -weighted images with 3.0 tesla MRI device and eight-channel phased-array head coil, we extracted left and right eye ball images, and then reconstructed 3D volume. The surface coordinates were calculated from 3D volume, fitting the ellipsoid model coordinates with the surface coordinates, and measured the axial length automatically. Measuring twenty one subjects, we compared the automatically measured values of axial length with the manually measured ones, then confirmed significant elongation in the axial length of myopia compared with that of emmetropia. Furthermore, there were no significant differences (P<0.05) between the means of automatic measurements and the manual ones. Accordingly, the automatic measurement process of axial length could be a tool for the elucidation of the mechanism of myopia progression, which would be suitable for evaluating the axial length easily and noninvasively. (author)
Application of five formulas in the elderly cataract patients with long axial length
Directory of Open Access Journals (Sweden)
Wei Fang
2017-07-01
Full Text Available AIM: To compare the accuracy of intraocular lens(IOLpower calculations by using five formulas(Haigis, SRK-T, Hoffer Q, Holladay-1, SRK-Ⅱin eyes with long axial lengths in order to improve the accuracy of predicating IOL powers. METHODS: Fifty-one eyes of 51 cases of age-related cataract and with mild long axial(24.5mm27mmwere collected who's optical biometry were performed by the Zeiss IOL Master500 before operation. They underwent regular phacoemulsification and posterior chamber IOL implantation. The actual postoperative refraction was measured with the methods of phoropter and subjective optometry 3mo after surgery. Then we compared the differences of the predicted and actual postoperative refraction of the five formulas in each group. RESULTS: In the mild axial lengths cases, the differences between SRK Ⅱ formula and the other four formulas were statistically significant(PPP>0.05. In the moderate and severe long axial lengths cases, the differences between SRK Ⅱ formula and the other four formulas were statistically significant(PPP>0.05. The differences of all the five formulas between the two groups were statistically significant(PCONCLUSION: In the mild axial lengths cases, Haigis, SRK-T, Hoffer Q, Holladay-1 performed well. In the moderate and severe long axial lengths cases, Haigis, SRK-T and Holladay-1 performed better than other formulas. The accuracy of all the five formulas decreases as the axial length getting longer.
Compression response of tri-axially braided textile composites
Song, Shunjun
2007-12-01
This thesis is concerned with characterizing the compression stiffness and compression strength of 2D tri-axially braided textile composites (2DTBC). Two types of 2DTBC are considered differing only on the resin type, while the textile fiber architecture is kept the same with bias tows at 45 degrees to the axial tows. Experimental, analytical and computational methods are described based on the results generated in this study. Since these composites are manufactured using resin transfer molding, the intended and as manufactured composite samples differ in their microstructure due to consolidation and thermal history effects in the manufacturing cycle. These imperfections are measured and the effect of these imperfections on the compression stiffness and strength are characterized. Since the matrix is a polymer material, the nonuniform thermal history undergone by the polymer at manufacturing (within the composite and in the presence of fibers) renders its properties to be non-homogenous. The effects of these non-homogeneities are captured through the definition of an equivalent in-situ matrix material. A method to characterize the mechanical properties of the in-situ matrix is also described. Fiber tow buckling, fiber tow kinking and matrix microcracking are all observed in the experiments. These failure mechanisms are captured through a computational model that uses the finite element (FE) technique to discretize the structure. The FE equations are solved using the commercial software ABAQUS version 6.5. The fiber tows are modeled as transversely isotropic elastic-plastic solids and the matrix is modeled as an isotropic elastic-plastic solid with and without microcracking damage. Because the 2DTBC is periodic, the question of how many repeat units are necessary to model the compression stiffness and strength are examined. Based on the computational results, the correct representative unit cell for this class of materials is identified. The computational models and
Method for calibration of an axial tomographic scanner
International Nuclear Information System (INIS)
Sparks, R.A.
1977-01-01
The method of calibrating an axial tomographic scanner including frame means having an opening therein in which an object to be examined is to be placed, source and detector means mounted on the frame means for directing one or more beams of penetrating radiation through the object from the source to the detector means, and means to rotate the scanner including the source and detector means about the object whereby a plurality of sets of data corresponding to the transmission or absorption by the object of a plurality of beams of penetrating radiation are collected; the calibration method comprising mounting calibration means supporting an adjustable centering member onto the frame means, positioning the adjustable centering member at approximately the center of rotation of the scanner, placing position-sensitive indicator means adjacent the approximately centered member, rotating the scanner and the calibration means mounted thereon at least one time and, if necessary, adjusting the positioning of the centering member until the centering member is coincident with the center of rotation of the scanner as determined by minimum deflection of the position-sensitive indicator means, rotating and translating the source and detector means and determining for each angular orientation of the frame means supporting the source and detector means the central position of each translational scan relative to the centered member and/or if a plurality of detectors are utilized with the detector means for each planar slice of the object being examined, the central position of each translational scan for each detector relative to the centered member
Effectiveness of Adalimumab in Non-radiographic Axial Spondyloarthritis
Cantarini, Luca; Fabbroni, Marta; Talarico, Rosaria; Costa, Luisa; Caso, Francesco; Cuneo, Gian Luca; Frediani, Bruno; Faralli, Gabriele; Vitale, Antonio; Brizi, Maria Giuseppina; Sabadini, Luciano; Galeazzi, Mauro
2015-01-01
Abstract The primary aim of the study was to evaluate the long-term effectiveness of adalimumab (ADA) in a cohort of non-radiographic axial spondyloarthritis (nr-axSpA), and the secondary aims were to identify predictive factors of response and evaluate radiological progression. We evaluated 37 patients (male/female: 12/25; mean age 49 ± 14; mean disease duration: 6.3 ± 5.8) with active nr-axSpA (Assessment of SpondyloArthritis International Society criteria), despite the treatment with ≥1 nonsteroidal anti-inflammatory drug for at least 3 months, initiating the treatment with ADA 40 mg every other week. Patients were treated for 24 months, and evaluated at baseline, 6, 12, and 24 months. Outcome measures included Ankylosing Spondylitis Disease Activity Score, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and Bath Ankylosing Spondylitis Functional Index. Radiograph of the spine and sacroiliac joints and magnetic resonance of the sacroiliac joints were performed at baseline and according to the standard of assessment for the disease. The proportion of patients that achieved a BASDAI50 response at 6, 12 and 24 months was 51.3%, 70.3%, and 76.8%, respectively. Treatment was well tolerated with no unexpected adverse events and/or serious adverse events. All patients remained on treatment for 2 years, with a good compliance. We did not identify any predictive factor of response to therapy. Moreover, modified Stoke Ankylosing Spondylitis Spine Score and Spondyloarthritis Research Consortium of Canada scores showed a trend of improvement during the study period. ADA was effective on clinical and radiological outcomes at 2-year follow-up; thus, early treatment with ADA may prevent radiographic damage and be associated with low disease activity or remission. Moreover, data from this cohort study have confirmed safety and tolerability profile of ADA in nr-axSpA in the long term. PMID:26222847
Measurement technique of calcaneal varus from axial view radiograph
Directory of Open Access Journals (Sweden)
Thossart Harnroongroj
2015-01-01
Full Text Available Background: Medial displaced posterior calcaneal tubercle creates varus deformity of an intraarticular calcaneal fracture. The fracture involves posterior calcaneal facet and the calcaneal body so we developed a measurement technique representing the angle between posterior facet and long axis of calcaneus using lateral malleolus and longitudinal bone trabeculae of posterior calcaneal tubercle as references to obtain calcaneal varus angle. Materials and Methods: 52 axial view calcaneal radiographs of 26 volunteers were studied. Angles between posterior facet and long axis of calcaneus were measured using the measurements 1 and 2. Angle of measurement 1, as gold standard, was obtained from long axis and posterior facet of calcaneus whereas measurement 2 was obtained from a line, perpendicular to apex curve of lateral cortex of the lateral malleolus and a line parallel to the longitudinal bone trabeculae of posterior calcaneal tubercle. No more than 3° of difference in the angle of both measurements was accepted. Reliability of the measurement 2 was statistically tested. Results: Angles of measurement 1 and 2 were 90.04° ± 4.00° and 90.58° ± 3.78°. Mean of different degrees of both measurements was 0.54° ± 2.31° with 95% of confidence interval: 0.10°-1.88°. The statistical analysis of measurement 1 and 2 showed more than 0.75 of ICC and 0.826 of Pearson correlation coefficient. Conclusion: Technique of measurement 2 using lateral malleolus and longitudinal bone trabeculae of posterior calcaneal tubercle as references has strong reliability for representing the angle between long axis and posterior facet of calcaneus to achieve calcaneal varus angle.
Measurement technique of calcaneal varus from axial view radiograph.
Harnroongroj, Thossart; Tangmanasakul, Akegapon; Choursamran, Nattapol; Sudjai, Narumol; Harnroongroj, Thos
2015-01-01
Medial displaced posterior calcaneal tubercle creates varus deformity of an intraarticular calcaneal fracture. The fracture involves posterior calcaneal facet and the calcaneal body so we developed a measurement technique representing the angle between posterior facet and long axis of calcaneus using lateral malleolus and longitudinal bone trabeculae of posterior calcaneal tubercle as references to obtain calcaneal varus angle. 52 axial view calcaneal radiographs of 26 volunteers were studied. Angles between posterior facet and long axis of calcaneus were measured using the measurements 1 and 2. Angle of measurement 1, as gold standard, was obtained from long axis and posterior facet of calcaneus whereas measurement 2 was obtained from a line, perpendicular to apex curve of lateral cortex of the lateral malleolus and a line parallel to the longitudinal bone trabeculae of posterior calcaneal tubercle. No more than 3° of difference in the angle of both measurements was accepted. Reliability of the measurement 2 was statistically tested. Angles of measurement 1 and 2 were 90.04° ± 4.00° and 90.58° ± 3.78°. Mean of different degrees of both measurements was 0.54° ± 2.31° with 95% of confidence interval: 0.10°-1.88°. The statistical analysis of measurement 1 and 2 showed more than 0.75 of ICC and 0.826 of Pearson correlation coefficient. Technique of measurement 2 using lateral malleolus and longitudinal bone trabeculae of posterior calcaneal tubercle as references has strong reliability for representing the angle between long axis and posterior facet of calcaneus to achieve calcaneal varus angle.
Beyond axial symmetry: An improved class of models for global data
Castruccio, Stefano
2014-03-01
An important class of models for data on a spherical domain, called axially symmetric, assumes stationarity across longitudes but not across latitudes. The main aim of this work is to introduce a new and more flexible class of models by relaxing the assumption of longitudinal stationarity in the context of regularly gridded climate model output. In this investigation, two other related topics are discussed: the lack of fit of an axially symmetric parametric model compared with a non-parametric model and to longitudinally reversible processes, an important subclass of axially symmetric models.
Dispersion sensitivity of large-scale axial gradient index glass for spherochromat doublets
Manhart, Paul K.; Hunter, Boyd V.; Blankenbecler, Richard
1999-10-01
Bi-AGRIN cemented doublets, super corrected for zero axial color, spherical aberration and sphero-chromatism can show polychromatic performance in the range of 0.004 waves PV or better at the red and blue wavelengths for speeds up to F/2. These doublets are comprised of two elements of axial gradient index glass. The crown and flint elements are each designed with separate and distinct gradient glass lines, giving each element an axial gradient in refractive index and dispersion. This paper examines one design and its performance sensitivity to dispersion modeling via the Buchdahl and Sellmeier dispersion equations.
Directory of Open Access Journals (Sweden)
Handa Amit
2016-07-01
Full Text Available The present study emphasizes on joints two industrially important materials AISI 304 with AISI 1021steels, produced by friction welding have been investigated. Samples were welded under different axial pressures ranging from 75MPa to 135MPa, at constant speed of 920rpm. The tensile strength, torsional strength, impact strength and micro hardness values of the weldments were determined and evaluated. Simultaneously the fractrography of the tensile tested specimens were carried out, so as to understand the failure analysis. It was observed that improved mechanical properties were noticed at higher axial pressures. Ductile failures of weldments were also observed at 120MPa and 135MPa axial pressures during fractography analysis.
Bufares, Ahmed M.; Wahid, M. A.
2012-06-01
The qualitative study has been carried out to investigate the effect of axial velocity of unburned gases on the flame characteristics during flame flashback in rotating burner. Our focus of study mainly on the flame shape and its behavior during flashback. It is found that the flame shape has been affected by the unburned gases axial velocity. Two flame shapes have been noticed the plate shape with cusp flame "fish flame" and upset dome flame. The cases that have been studied are flames at rotating speed 1200 rpm and 1620 rpm and several unburned gases axial velocity. Double concentric Bunsen rotating burner has been used in the study.
Zhou, Yanru; Zhao, Yuxiang; Tian, Hui; Zhang, Dengwei; Huang, Tengchao; Miao, Lijun; Shu, Xiaowu; Che, Shuangliang; Liu, Cheng
2016-12-01
In an axial magnetic field (AMF), which is vertical to the plane of the fiber coil, a polarization-maintaining fiber optic gyro (PM-FOG) appears as an axial magnetic error. This error is linearly related to the intensity of an AMF, the radius of the fiber coil, and the light wavelength, and also influenced by the distribution of fiber twist. When a PM-FOG is manufactured completely, this error only appears a linear correlation with the AMF. A real-time compensation model is established to eliminate the error, and the experimental results show that the axial magnetic error of the PM-FOG is decreased from 5.83 to 0.09 deg/h in 12G AMF with 18-dB suppression.
Optimum design of laminated composite under axial compressive load
Indian Academy of Sciences (India)
... c/a ratio: 0.2. 3. Results and discussion. Both symmetric and anti-symmetric laminates, with simply supported and clamped edges are considered for computation. The validation of the genetic algorithm code is carried out on three sets of problems for which results are available. The tests problems are hard globalization ...
Leng, Xueyuan; Kolesnikov, Yurii B.; Krasnov, Dmitry; Li, Benwen
2018-01-01
The effect of an axial homogeneous magnetic field on the turbulence in the Taylor-Couette flow confined between two infinitely long conducting cylinders is studied by the direct numerical simulation using a periodic boundary condition in the axial direction. The inner cylinder is rotating, and the outer one is fixed. We consider the case when the magnetic Reynolds number Rem ≪ 1, i.e., the influence of the induced magnetic field on the flow is negligible that is typical for industry and laboratory study of liquid metals. Relevance of the present study is based on the similarity of flow characteristics at moderate and high magnetic field for the cases with periodic and end-wall conditions at the large flow aspect ratio, as proven in the earlier studies. Two sets of Reynolds numbers 4000 and 8000 with several Hartmann numbers varying from 0 to 120 are employed. The results show that the mean radial induced electrical current, resulting from the interaction of axial magnetic field with the mean flow, leads to the transformation of the mean flow and the modification of the turbulent structure. The effect of turbulence suppression is dominating at a strong magnetic field, but before reaching the complete laminarization, we capture the appearance of the hairpin-like structures in the flow.
Ratio Bias and Policy Preferences
DEFF Research Database (Denmark)
Pedersen, Rasmus Tue
2016-01-01
Numbers permeate modern political communication. While current scholarship on framing effects has focused on the persuasive effects of words and arguments, this article shows that framing of numbers can also substantially affect policy preferences. Such effects are caused by ratio bias, which...
Gender Ratios for Reading Difficulties
Hawke, Jesse L.; Olson, Richard K.; Willcut, Erik G.; Wadsworth, Sally J.; DeFries, John C.
2009-01-01
The prevalence of reading difficulties is typically higher in males than females in both referred and research-identified samples, and the ratio of males to females is greater in more affected samples. To explore possible gender differences in reading performance, we analysed data from 1133 twin pairs in which at least one member of each pair had…
Issues about axial diffusion during segmental hair analysis.
Kintz, Pascal
2013-06-01
The detection of a single drug exposure in hair (doping offence, drug-facilitated crime) is based on the presence of the compound of interest in the segment corresponding to the period of the alleged event. However, in some cases, the drug is detected in consecutive segments. As a consequence, interpretation of the results is a challenge that deserves particular attention. Literature evaluation and data obtained from the 20-year experience in drug testing in hair of the author are used as the basis to establish a theory to validate the concept of single exposure in authentic forensic cases where the drug is detected in 2 or 3 segments. The gained experience recommends to wait for 4-5 weeks after the alleged event and then to collect strands of hair. Assuming normal hair growth rate (1 cm/mo), it is advisable to cut the strand into 3 segments of 2 cm to document eventual exposure. Administration of a single dose would be confirmed by the presence of the drug in the proximal 2-cm segment (root), whereas not detected in the 2 other segments. However, in the daily experience of the author, it was noticed that sometimes (about 1 case from 10 examinations), the drug can be detected in 2 or 3 consecutive segments. Such a disposition was even observed in volunteer experiments in the literature. As it was also described for cocaine in early 1996, there is considerable variability in the area over which incorporated drug can be distributed in the hair shaft and in the rate of axial distribution of drug along the hair shaft. This can explain why a small amount of drug, as compared with the concentration in the proximal segment, can be measured in the second segment, as a result of an irregular movement. Another explanation for broadening the band of positive hair from a single dose is that drugs and metabolites are incorporated into hair during formation of the hair shaft via diffusion from sweat and other secretions. The presence of confounding interferences in the hair
Multi-axial active isolation for seismic protection of buildings
Chang, Chia-Ming
Structural control technology has been widely accepted as an effective means for the protection of structures against seismic hazards. Passive base isolation is one of the common structural control techniques used to enhance the performance of structures subjected to severe earthquake excitations. Isolation bearings employed at the base of a structure naturally increase its flexibility, but concurrently result in large base displacements. The combination of base isolation with active control, i.e., active base isolation, creates the possibility of achieving a balanced level of control performance, reducing both floor accelerations as well as base displacements. Many theoretical papers have been written by researchers regarding active base isolation, and a few experiments have been performed to verify these theories; however, challenges in appropriately scaling the structural system and modeling the complex nature of control-structure interaction have limited the applicability of these results. Moreover, most experiments only focus on the implementation of active base isolation under unidirectional excitations. Earthquakes are intrinsically multi-dimensional, resulting in out-of-plane responses, including torsional responses. Therefore, an active isolation system for buildings using multi-axial active control devices against multi-directional excitations must be considered. The focus of this dissertation is the development and experimental verification of active isolation strategies for multi-story buildings subjected to bi-directional earthquake loadings. First, a model building is designed to match the characteristics of a representative full-scale structure. The selected isolation bearings feature low friction and high vertical stiffness, providing stable behavior. In the context of the multi-dimensional response control, three, custom-manufactured actuators are employed to mitigate both in-plane and out-of-plane responses. To obtain a high-fidelity model of the
Patients with fibromyalgia rarely fulfil classification criteria for axial spondyloarthritis.
Baraliakos, Xenofon; Regel, Andrea; Kiltz, Uta; Menne, Hans-Jürgen; Dybowski, Friedrich; Igelmann, Manfred; Kalthoff, Ludwig; Krause, Dietmar; Saracbasi-Zender, Ertan; Schmitz-Bortz, Elmar; Braun, Jürgen
2017-09-06
The Assessments of Spondyloarthritis international Society (ASAS) classification criteria for axial spondyloarthritis (axSpA) have been criticized because of insufficient differentiation towards FM. The aim of this study was to compare the performance of currently used classification criteria in patients diagnosed with axSpA or FM. Patients were prospectively included if diagnosed with axSpA or FM by the treating rheumatologist and evaluated by an independent examiner for fulfilment of the classification criteria for axSpA (ASAS criteria) and/or FM (1990 ACR classification and 2010 ACR diagnostic criteria). Patients with axSpA were stratified based on classification as non-radiographic axSpA (nr-axSpA) or AS. Symptom severity was assessed by established disease-related questionnaires. Overall, 300 patients were included, 100 with FM and 200 with axSpA of which 100 each had nr-axSpA and AS. Almost all FM patients fulfilled the 2010 (100%) and 1990 ACR criteria (98%) for FM, but only 2% fulfilled the ASAS criteria. When calculations were based on only the FM patients with available HLA-B27 results (n = 40), the proportion fulfilling the ASAS criteria was 5%. All axSpA patients met the ASAS criteria but also the 2010 (24%) and 1990 (13.5%) FM criteria. More patients with AS (29% and 19%) than with nr-axSpA (19% and 8%) fulfilled the 2010 and 1990 FM criteria, respectively. FM patients only rarely fulfil classification criteria for axSpA but some axSpA patients also fulfil FM criteria. Since this was more frequent in patients with AS it may be related to the severity and duration of chronic pain in axSpA patients. Assessment instruments evaluated in axSpA are not disease-specific. The phenomenon of central pain sensitization in rheumatic diseases deserves more study. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com
Controllable rectification of the axial expansion in the thermally driven artificial muscle
Yue, Donghua; Zhang, Xingyi; Yong, Huadong; Zhou, Jun; Zhou, You-He
2015-09-01
At present, the concept of artificial muscle twisted by polymers or fibers has become a hot issue in the field of intelligent material research according to its distinguishing advantages, e.g., high energy density, large-stroke, non-hysteresis, and inexpensive. The axial thermal expansion coefficient is an important parameter which can affect its demanding applications. In this letter, a device with high accuracy capacitive sensor is constructed to measure the axial thermal expansion coefficient of the twisted carbon fibers and yarns of Kevlar, and a theoretical model based on the thermal elasticity and the geometrical features of the twisted structure are also presented to predict the axial expansion coefficient. It is found that the calculated results take good agreements with the experimental data. According to the present experiment and analyses, a method to control the axial thermal expansion coefficient of artificial muscle is proposed. Moreover, the mechanism of this kind of thermally driven artificial muscle is discussed.
Posterior atlanto-occipital and atlanto-axial area and its surgical interest
Directory of Open Access Journals (Sweden)
Newton José Godoy Pimenta
2014-10-01
Full Text Available Classic anatomical studies describe two membranes – atlanto-occipital and atlanto-axial in the posterior aspect of the craniocervical region. During many surgical procedures in this area, however, we have not found such membranes. Objective To clarify the anatomical aspects and structures taking part of the posterior atlanto-occipital and atlanto-axial area. Method Analysis of histological cuts of three human fetuses and anatomical studies of 8 adult human cadavers. Results In both atlanto-occipital and atlanto-axial areas, we have observed attachment between suboccipital deep muscles and the spinal cervical dura. However, anatomical description of such attachments could not be found in textbooks of anatomy. Conclusion Our study shows the absence of the classical atlanto-occipital and atlanto-axial membranes; the occipito-C1 and C1-C2 posterior intervals are an open area, allowing aponeurotic attachment among cervical dura mater and posterior cervical muscles.
Axial distortion as a sensor of supercoil changes: a molecular model ...
Indian Academy of Sciences (India)
Unknown
2001-12-14
NS or HU function, paving the way to resolving the question of direct versus indirect role of axial distortion. Acknowledgements. The work is supported by a grant from the Council of Scientific and Industrial Research, Government ...
Control of the axial offset in a nuclear reactor at power maneuvering
Directory of Open Access Journals (Sweden)
Maksim V. Maksimov
2014-12-01
Full Text Available High reliability and security of power unit are basic requirements when the power unit maneuvering mode operation. The reactor stability under disturbances both at steady load and maneuvering load embodies the guarantees of power unit safe and reliable operation. A quantitative measure of the reactor stability is assessed by the axial offset representing the technological characteristics of energy release uniformity, therefore the axial offset minimum deviation is WWER-1000 operation efficiency measure. The power unit capacity automated control systems’ influence on axial offset under maneuvering mode is investigated. Considered is the power unit compromise-combined control program, which maintains a constant axial offset value when power unit switching from one power level to another.
A free vibration of beams carrying a concentrated mass under distributed axial forces
International Nuclear Information System (INIS)
Nagai, Ken-ichi; Nagaya, Kosuke; Takeda, Sadahiko; Arai, Noriyuki.
1988-01-01
The free bending vibrations of beams with a concentrated mass subjected to axial forces caused by axial acceleration are analyzed by the Galerkin method, introducing the mode shape functions which are the sum of the products of the finite power series and the trigonometrical function. This analytical method makes it easy to construct the equations of motion in each boundary condition only by exchanging the coefficients of the finite power series. Numerical calculations are carried out under four sets of boundary conditions combined with simply supported and clamped edges. The natural frequencies and the corresponding modes of vibration are determined under both various locations of the concentrated mass and axial forces. it is found that the transverse inertia force and the axial force, due to the concentrated mass, have significant effects on the change of the natural frequencies for beams. Furthermore the distinction of boundary conditions gives predominant influence to the variation of natural frequencies. (author)
Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation, Phase I
National Aeronautics and Space Administration — We propose to demonstrate key elements of feasibility for a high speed automated time domain terahertz computed axial tomography (TD-THz CT) non destructive...
Melt Motion Due to Peltier Marking During Bridgman Crystal Growth with an Axial Magnetic Field
Sellers, C. C.; Walker, John S.; Szofran, Frank R.; Motakef, Shariar
2000-01-01
This paper treats a liquid-metal flow inside an electrically insulating cylinder with electrically conducting solids above and below the liquid region. There is a uniform axial magnetic field, and there is an electric current through the liquid and both solids. Since the lower liquid-solid interface is concave into the solid and since the liquid is a better electrical conductor than the adjacent solid, the electric current is locally concentrated near the centerline. The return to a uniform current distribution involves a radial electric current which interacts with the axial magnetic field to drive an azimuthal flow. The axial variation of the centrifugal force due to the azimuthal velocity drives a meridional circulation with radial and axial velocities. This problem models the effects of Peltier marking during the vertical Bridgman growth of semiconductor crystals with an externally applied magnetic field, where the meridional circulation due to the Peltier Current may produce important mixing in the molten semiconductor.
DEFF Research Database (Denmark)
Enemark, Søren; Santos, Ilmar
2014-01-01
by two passive magnetic bearings using axially-aligned neodymium cylinder magnets. The magnetic bearing housings are flexibly supported, allowing horizontal motions. The housings are connected to each other by means of elastic beams. The shaft is free in one end and coupled to a DC motor on the other......-linear stiffness. In this investigation passive magnetic bearings using axially- aligned neodymium cylinder magnets are investigated. The cylinder magnets are axially magnetised for rotor as well as bearings. Compared to bearings with radial magnetisation, the magnetic stiffness of axially-aligned bearings...... with a multibody system composed of rigid rotor and flexible foundation. The magnetic eccentricities of the shaft magnets are modelled using the distances (amplitudes) and directions (phase angles) between the shaft axis and the centre of the magnetic fields generated. A perturbation method, i.e. harmonic...
[Progress on atlanto-axial pedicle screw fixation through posterior approach].
Li, Guo-Qing; Ma, Wei-Hu; Liu, Guan-Yi
2014-06-01
The present of atlanto-axial pedicle screw fixation through posterior approach provide a new remedy for treating instability of pillow and cervical. A lot of researches have reported feasibility of atlanto-axial pedicle screw fixation, the results showed that it had advantages of easily exposure, less blood loss, shorter operative time, especially in treating as remedy fixation for atlanto-axial joint screw, atlas lateral mass screws and pedicle screw caused by injuries of tumor,inflammation and trauma. If not done properly, it can cause serious complications, such as iatrogenic fracture,injuries of vertebral artery and cervical spinal cord. Therefore,the safty and effectiveness of atlanto-axial pedicle screw fixation may be focus of research.
Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation, Phase II
National Aeronautics and Space Administration — In this Phase 2 project, we propose to develop, construct, and deliver to NASA a computed axial tomography time-domain terahertz (CT TD-THz) non destructive...
'GRC1.5': Uptower Gearbox Testing to Investigate Bearing Axial Cracking
Energy Technology Data Exchange (ETDEWEB)
Keller, Jonathan; Vaes, David; McNiff, Brian
2016-02-16
This presentation focuses on the investigation of bearing axial cracking using the GRC1.5 uptower gearbox. Topics covered include the testing options considered, the project goal, and current and near-term activities.
On the axially symmetric non-rotating vacuum solutions of Rosen's equations
International Nuclear Information System (INIS)
Bozhkov, Y.
1990-10-01
It is shown that all axially symmetric nonrotating solutions of Rosen's field equations can be expressed in terms of two harmonic functions. It is also shown that the total energy of Rosen's metric is Mc 2 . (author). 8 refs
A review of creep analysis and design under multi-axial stress states
International Nuclear Information System (INIS)
Yao, H.-T.; Xuan Fuzhen; Wang Zhengdong; Tu Shantung
2007-01-01
The existence of multi-axial states of stress cannot be avoided in elevated temperature components. It is essential to understand the associated failure mechanisms and to predict the lifetime in practice. Although metal creep has been studied for about 100 years, many problems are still unsolved, in particular for those involving multi-axial stresses. In this work, a state-of-the-art review of creep analysis and engineering design is carried out, with particular emphasis on the effect of multi-axial stresses. The existing theories and creep design approaches are grouped into three categories, i.e., the classical plastic theory (CPT) based approach, the cavity growth mechanism (CGM) based approach and the continuum damage mechanics (CDM) based approach. Following above arrangements, the constitutive equations and design criteria are addressed. In the end, challenges on the precise description of the multi-axial creep behavior and then improving the strength criteria in engineering design are presented
A study on multi-axial fatigue model based on structural stress
International Nuclear Information System (INIS)
Kim, Cheol; Kim, Jong Sung; Jin, Tae Eun; Dong, P.
2004-01-01
In nuclear components, cyclic loadings that cause complex states of stress are common. Through a reference review, four sources of the multi-axial fatigue data were collected from LBF, University of Illinois, EPRI, and TWI. All these tests were conducted using tube to flange specimens with a circumferential fillet welds. The loading conditions were mostly bending/ torsion combinations, except that TWI used tension/ torsion combinations. None of fatigue correlation parameters have been demonstrated to be satisfactory in correlating the multi-axial fatigue data outside of their own. In this paper, we proposed the characterizing multi-axial fatigue behavior in terms of the structural stress methods by using some of the well-known multi-axial fatigue data available in the references
The Role of Computed Axial Tomography in the Study of the Child with Minimal Brain Dysfunction.
Thompson, J. S.; And Others
1980-01-01
It was concluded that computed axial tomography of the brain is not a necessary screening procedure in the evaluation of the child with minimal brain dysfunction or learning disabilities unless there is evidence of a focal neurologic deficit. (Author)