WorldWideScience

Sample records for beam continuous uniform

  1. Uniform beam distributions using octupoles

    International Nuclear Information System (INIS)

    The Gaussian beam profile of the BNL 200 MeV H- Linac beam at the Radiation Effects Facility target location was transformed into a rectangular profile with almost uniform distribution by placing two octupole magnetic elements at particular locations along the beam line. Experimental results of the beam profile projection in the horizontal and vertical planes, with and without octupoles, are presented and compared with third order calculations. 7 refs., 3 figs

  2. Calculation of Uniform of Beam Scanning

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    For the electron beam application, it is always scanned by a dipole magnet. The uniform of the scanning has great influence for some application, such as the irradiation of the thyristor. There are two methods for improving the scanning uniform:

  3. Continuous Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1996-01-01

    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution at the...

  4. Analytical examination of a spiral beam scanning method for uniform irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Mitsuhiro; Okumura, Susumu; Arakawa, Kazuo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    A new circular beam scanning method for uniform irradiation of high-energy, intense ion beams over a large area has been developed. A sweeping speed and a trajectory density in a radial direction are kept constant to obtain uniform fluence distribution. A radial position of a beam spot on a target and an angular frequency of the circular motion are expressed by an irrational function of time. The beam is swept continuously, and a beam trajectory becomes spiral. More than 90 % uniformity of the fluence distribution can been achieved over a large area. (author)

  5. Uniform irradiation system using beam scanning method for cyclotron

    International Nuclear Information System (INIS)

    JAERI AVF-cyclotron is equipped with an ion beam scanner for large area irradiation. The two-dimensional fluence distribution of ion beam obtained using cellulose triacetate film dosimeter was not uniform. This is resulted from the distortion of excitation current for electromagnet of the scanner. So, the beam scanning condition, i.e., the relation between the ion species, the beam profile and the scanning width, was extremely limited to make a good uniformity. We have developed a beam scanning simulator to get fluence distributions by calculation and then compared the simulated distributions with the measured ones. It was revealed that the both of them are in good agreement and the beam scanning condition to get good uniformity was led by using this simulator. On the basis of these results, the power supply of scanner was improved. A good uniformity of beam distribution was available. (author)

  6. Radial smoothing for improving laser-beam irradiance uniformity.

    Science.gov (United States)

    Zhong, Zheqiang; Hou, Pengcheng; Zhang, Bin

    2015-12-15

    Laser-beam irradiation uniformity is a key issue in inertial confinement fusion research. We propose a radial smoothing (RS) approach in which the speckle in a focal plane is smoothed by the radial redistribution through fast focal zooming. This focal zooming is generated by introducing the periodical spherical wavefront modulation to the laser beam, based on an optical Kerr medium and its pump laser with the temporal profile of a Gaussian pulse train. The utilization of RS significantly improves the laser-beam uniformity without obvious impact on the performance of the high-power laser system. PMID:26670528

  7. Spiral wobbling beam illumination uniformity in HIF fuel target implosion

    OpenAIRE

    Kawata S.; Kurosaki T.; Koseki S.; Hisatomi Y.; Barada D.; Ma Y.Y.; Ogoyski A.I.

    2013-01-01

    A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF) throughout the heavy ion beam (HIB) driver pulse by a newly introduced spiraling beam axis motion in the first two rotations. The wobbling HIB illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the i...

  8. Ring lens for producing uniform density ion beams

    International Nuclear Information System (INIS)

    Frequently one needs to irradiate a circular target uniformly with a positive ion beam from an accelerator. The typical beam is peaked on the axis and has a more or less Gaussian radial distribution, so that it would be advantageous to be able to fold the tails of the Gaussian inward to give a uniform flux on the target. A lens, which is quite unconventional, was designed and built for that purpose and has operated successfully for many months on the 5 MV electrostatic accelerator at this laboratory. The general concepts and lens structure are presented here

  9. Ring lens for focusing ion beams to uniform densities

    International Nuclear Information System (INIS)

    An electrostatic lens was designed and built to focus a beam of positive ions into uniform density on a target. The lens has two concentric field regions with a grid separating the inner zero field from the outer radial field. For proper operation the incident ions must emanate with axial symmetry and Gaussian or similar divergence from a small source. An appendix is included on the symmetrization of elliptical beams by a quadrupole singlet lens. (U.S.)

  10. Beam moments and angular momentum in non-uniformly polarized beams

    Science.gov (United States)

    Serna, Julio; Piquero, Gemma

    2009-05-01

    The angular momentum of non-uniformly totally polarized beams is investigated using methods from the beam characterization approach. The relationship between the elements of the beam matrix for the two components of the field and the angular momentum is given. The unconventional distribution of the polarization across the beam profile could result in contributions to both the spin and orbital terms of the angular momentum. To illustrate this, a particular example with a vortex beam is considered.

  11. Light beams focusing in periodically non-uniform crystalline medium

    Directory of Open Access Journals (Sweden)

    S.N.Kurilkina

    2002-03-01

    Full Text Available In the present paper the peculiarities of propagation and diffraction of optical waves in the crystalline periodically non-uniform media are considered. The dependence of light beam divergence in the crystal on curvatures of wave vector surface is obtained. It is shown, that presence of the periodic non-uniformity of the crystal and natural anisotropy lead to essential deformation of wave vector surface, namely, to the appearance of local regions with negative curvature and, hence, to the effect of light focusing in corresponding directions. The application of uniform electric field may intensify the light focusing. The crystalline diffraction lenses are proposed which are controlled by electric field and variation of incident light polarization.

  12. Characterization of non-uniformly totally polarized beams

    Science.gov (United States)

    Martinez-Herrero, R.; Mejías, P. M.; Piquero, G.

    2006-02-01

    Several overall parameters are introduced to characterize the linear or circular polarization content of a non-uniformly totally polarized beam over the region of its wavefront where the irradiance is significant. These parameters are determined from the values of the Stokes parameters. Experimental examples are also given to check both, the physical meaning of the proposed parameters and the validity of the measurement procedure.

  13. Strong convergence theorems for uniformly continuous pseudocontractive maps

    International Nuclear Information System (INIS)

    Let K be a nonempty closed convex subset of a real Banach space E and let T : K -→ K be a uniformly continuous pseudocontraction. Fix any u element of K . Let {xn} be defined by the iterative process: x0 element of K , xn+1 := μn(αnTxn + (1 - αn)xn) + (1 - μn)u. Let δ (ε) denote the modulus of continuity of T with pseudo-inverse φ . If { φ (t)/ t : 0 n} are bounded then, under some mild conditions on the sequences {αn}n and { μn}n, the strong convergence of {xn} to a fixed point of T is proved. In the special case where T is Lipschitz, it is shown that the boundedness assumptions on { φ (t)/ t : 0 n} can be dispensed with. (author)

  14. Probabilistic properties of the continuous double auction - uniform case

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Martin

    Prague : Czech University of Life Sciences Prague, 2009 - (Brožová, H.), s. 317-322 ISBN 978-80-213-1963-9. [27th International Conference Mathematical Methods in Economics 2009. Kostelec nad Černými lesy (CZ), 09.09.2009-11.09.2009] R&D Projects: GA ČR GA402/07/1113; GA ČR GA402/09/0965; GA MŠk(CZ) LC06075 Institutional research plan: CEZ:AV0Z10750506 Keywords : continuous double auction * limit order market * statistical inference Subject RIV: AH - Economics http://library.utia.cas.cz/separaty/2009/E/smid-probabilistic properties of the continuous double auction - uniform case.pdf

  15. Spiraling Beam Illumination Uniformity on Heavy Ion Fusion Target

    CERN Document Server

    Kurosaki, T; Noguchi, K; Koseki, S; Barada, D; Ma, Y Y; Ogoyski, A I; Barnard, J J; Logan, B G

    2012-01-01

    A few percent wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF) by a spiraling beam axis motion in the paper. So far the wobbling heavy ion beam (HIB) illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may contribute to the reduction of the HIBs illumination nonuniformity. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be several 100MHz-1GHz. Three-dimensional HIBs illumination computations presented here show that the few percent wobbling HIBs illumination nonuniformity oscillates successfully with the same wobbling HIBs frequency.

  16. Constrained modes in control theory - Transmission zeros of uniform beams

    Science.gov (United States)

    Williams, T.

    1992-01-01

    Mathematical arguments are presented demonstrating that the well-established control system concept of the transmission zero is very closely related to the structural concept of the constrained mode. It is shown that the transmission zeros of a flexible structure form a set of constrained natural frequencies for it, with the constraints depending explicitly on the locations and the types of sensors and actuators used for control. Based on this formulation, an algorithm is derived and used to produce dimensionless plots of the zero of a uniform beam with a compatible sensor/actuator pair.

  17. Illumination non-uniformity of spirally wobbling beam in heavy ion fusion

    Science.gov (United States)

    Suzuki, T.; Noguchi, K.; Kurosaki, T.; Barada, D.; Kawata, S.; Ma, Y. Y.; Ogoyski, A. I.

    2016-03-01

    In inertial confinement fusion, the driver beam illumination non-uniformity leads a degradation of fusion energy output. The illumination non-uniformity allowed is less than a few percent in inertial fusion target implosion. Heavy ion beam (HIB) accelerator provides a capability to oscillate a beam axis with a high frequency. The wobbling beams may provide a new method to reduce or smooth the beam illumination non-uniformity. In this paper the HIBs wobbling illumination scheme was optimized.

  18. Spiral wobbling beam illumination uniformity in HIF fuel target implosion

    Directory of Open Access Journals (Sweden)

    Kawata S.

    2013-11-01

    Full Text Available A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF throughout the heavy ion beam (HIB driver pulse by a newly introduced spiraling beam axis motion in the first two rotations. The wobbling HIB illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may produce a time-dependent implosion acceleration, which reduces the Rayleigh-Taylor (R-T growth [Laser Part. Beams 11, 757 (1993, Nuclear Inst. Methods in Phys. Res. A 606, 152 (2009, Phys. Plasmas 19, 024503 (2012] and the implosion nonuniformity. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be several 100 MHz ∼ 1 GHz [Phys. Rev. Lett. 104, 254801 (2010]. Three-dimensional HIBs illumination computations present that the few % wobbling HIBs illumination nonuniformity oscillates with the same wobbling HIBs frequency.

  19. The Continuous Electron Beam Accelerator Facility

    International Nuclear Information System (INIS)

    On February 13, 1987, construction started on the Continuous Electron Beam Accelerator Facility - a 4-GeV, 200-μA, continuous beam, electron accelerator facility designed for nuclear physics research. The machine has a racetrack configuration with two antiparallel, 500-MeV, superconducting linac segments connected by beam lines to allow four passes of recirculation. The accelerating structure consists of 1500-MHz, five-cell niobium cavities developed at Cornell University. A liquid helium cryogenic system cools the cavities to an operating temperature of 2 K. Beam extraction after any three of the four passes allows simultaneous delivery of up to three beams of independently variable currents and different, but correlated, energies to the three experimental areas. Beam breakup thresholds exceed the design current by nearly two orders of magnitude. Project completion and the start of physics operations are scheduled for 1993. The total estimated cost is $255 million

  20. Irradiation uniformity of spherical targets by multiple uv beams from OMEGA

    International Nuclear Information System (INIS)

    Direct-drive laser fusion demands extremely high levels of irradiation uniformity to ensure uniform compression of spherical targets. The assessment of illumination uniformity of targets irradiated by multiple beams from the OMEGA facility is made with the aid of multiple beams spherical superposition codes, which take into account ray tracing and absorption and a detailed knowledge of the intensity distribution of each beam in the target plane. In this report, recent estimates of the irradiation uniformity achieved with 6 and 12 uv beams of OMEGA will be compared with previous measurements in the IR, and predictions will be made for the uv illumination uniformity achievable with 24 beams of OMEGA

  1. Helicon waves in uniform plasmas. IV. Bessel beams, Gendrin beams, and helicons

    Science.gov (United States)

    Urrutia, J. M.; Stenzel, R. L.

    2016-05-01

    Electromagnetic waves in the low frequency whistler mode regime are investigated experimentally and by digital data superposition. The radiation from a novel circular antenna array is shown to produce highly collimated helicon beams in a uniform unbounded plasma. The differences to Bessel beams in free space are remarked upon. Low divergence beams arise from the parallel group velocity of whistlers with phase velocity either along the guide field or at the Gendrin angle. Waves with angular momentum are produced by phasing the array in the circular direction. The differences in the field topologies for positive and negative modes numbers are shown. It is also shown that in uniform plasmas, the radial amplitude profile of the waves depends on the antenna field topology. Thus, there are no helicon "eigenmodes" with radial Bessel function profiles in uniform plasmas. It is pointed out that phase measurements in helicon devices indicate radial wave propagation which is inconsistent with helicon eigenmode theory based on paraxial wave propagation. Trivelpiece-Gould modes also exist in uniform unbounded plasmas.

  2. Metamaterial-based polarization scrambler for uniform illumination of laser beam

    CERN Document Server

    Ling, Xiaohui; Zhao, Chujun; Wen, Shuangchun; Fan, Dianyuan

    2011-01-01

    The uniform illumination of laser beam is imperative to inertial confinement fusion. As a uniform illumination technique, polarization smoothing reduces the beam non-uniformity by creating two orthogonally polarized beams with a selected angular separation or by an optic which scrambles the polarization in the near field. Here, we propose and demonstrate a metamaterial-based polarization scrambler for improving the illumination uniformity of laser beam by exploiting the ability of metamaterial in local polarization manipulation of beam upon transmission by tuning its local geometry. As a proof-of-principle, we exemplify this idea numerically in a simplified beam smoothing system using a typical L-shaped plasmonic metamaterial with locally varying structure geometry, from which the desired far-field polarization distribution can be obtained. The calculating results illustrate that this scrambler can effectively suppress the small-scale non-uniformity of the speckle pattern and shows a nearly same smoothing eff...

  3. Nonlinear free vibrations of centrifugally stiffened uniform beams at high angular velocity

    Science.gov (United States)

    Bekhoucha, F.; Rechak, S.; Duigou, L.; Cadou, J. M.

    2016-09-01

    In this paper, we study the bending nonlinear free vibrations of a centrifugally stiffened beam with uniform cross-section and constant angular velocity. The nonlinear intrinsic equations of motion used here are geometrically exact and specific to beams exhibiting large amplitude displacements and rotations associated with small strains. Based on the Timoshenko beam model, these equations are derived from Hamilton's principle, in which the warping is considered. All coupling terms are considered including Coriolis terms. The studied beams are isotropic with clamped-free boundary conditions. By combining the Galerkin method with the harmonic balance method, the equations of motion are converted into a quadratic function treated with a continuation method: the Asymptotic Numerical Method, where the generalized displacement vector is presented as a series expansion. While analysing the effect of the angular velocity, we determine the amplitude versus frequency variations which are plotted as backbone curves. Considering the first lagging and flapping modes, the changes in beam behaviour from hardening to softening are investigated and identified as a function of the angular velocity and the effect of shear. Particular attention is paid to high angular velocities for both Euler-Bernoulli and Timoshenko beams and the natural frequencies so obtained are compared with the results available in the literature.

  4. A continuous cold atomic beam interferometer

    International Nuclear Information System (INIS)

    We demonstrate an atom interferometer that uses a laser-cooled continuous beam of 87Rb atoms having velocities of 10–20 m/s. With spatially separated Raman beams to coherently manipulate the atomic wave packets, Mach–Zehnder interference fringes are observed at an interference distance of 2L = 19 mm. The apparatus operates within a small enclosed area of 0.07 mm2 at a bandwidth of 190 Hz with a deduced sensitivity of 7.8×10−5 rad/s/√(Hz) for rotations. Using a low-velocity continuous atomic source in an atom interferometer enables high sampling rates and bandwidths without sacrificing sensitivity and compactness, which are important for applications in real dynamic environments

  5. Formation of large-area heavy-ion uniform beams using multipole magnets in TIARA, JAEA

    International Nuclear Information System (INIS)

    A research and development study related to the uniformization of the transverse beam intensity distribution using multipole magnets is ongoing for a new uniform irradiation method of proton and heavy-ion beams at an azimuthally-varying-field cyclotron facility of TIARA in Japan Atomic Energy Agency. In this method, a uniform transverse intensity distribution can be formed by folding the tail of a Gaussian initial distribution into the inside with a nonlinear focusing force of multipole magnets. First, a Gaussian-like intensity distribution was generated from a complicated distribution of the beam accelerated by the cyclotron through multiple Coulomb scattering using a thin foil at a low loss of beam energy. The response of Gafchromic radiochromic films to various ion beams was investigated for the evaluation of the size and uniformity in a large-area beam. Large-area (>100 cm2) uniform distributions have been attained for argon ion beams of 4 ∼ 13 MeV/u, as well as for proton beams of 10 MeV. Heavy-ion uniform beams will be applied to research and production of functional materials. (author)

  6. INVARIANT REPRESENTATION FOR STOCHASTIC DIFFERENTIAL OPERATOR BY BSDES WITH UNIFORMLY CONTINUOUS COEFFICIENTS AND ITS APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    Guangyan JIA; Na ZHANG

    2013-01-01

    In this paper, we prove that a kind of second order stochastic differential op-erator can be represented by the limit of solutions of BSDEs with uniformly continuous coefficients. This result is a generalization of the representation for the uniformly continu-ous generator. With the help of this representation, we obtain the corresponding converse comparison theorem for the BSDEs with uniformly continuous coefficients, and get some equivalent relationships between the properties of the generator g and the associated so-lutions of BSDEs. Moreover, we give a new proof about g-convexity.

  7. Use of a tungsten filter to improve beam uniformity

    International Nuclear Information System (INIS)

    A general method for calculating the dose distribution in an irradiated volume is to evaluate the primary and scatter components separately according to the method described by Clarkson and Cunningham. It was found, however, that for a 6 MV Siemens accelerator the calculated dose overestimated the peripheral dose at depths beyond 10 cm by 3%-6%. The difference was attributed to the varying beam quality across the field. This beam quality variation was decreased by hardening the beam with a permanently installed 1/3 in. tungsten filter inserted between the beam flattening filter and the mirror base assembly. The tungsten filter had a more pronounced beam hardening effect at the beam edge than along the central ray. For example, the dose rate in air at the beam edge for a 30 x 30 cm2 field was 13% higher than along the central ray without the tungsten filter. The addition of the 1/8 in. filter decreased this horn to 6%. The beam quality along the central ray also increased. The tissue-air ratio for zero field size along the central ray increased by 2% with the addition of the tungsten filter. The scatter-air ratio, however, did not change with the added filter. Agreement within 1%-2% was achieved between the calculated and measured beam profiles at all depths in a phantom when the tungsten filter was added

  8. Dissipative instability of overlimiting electron beam in no uniform cross-section system

    International Nuclear Information System (INIS)

    Paper presents a type of streaming instabilities with new, previously unknown physics. It realizes under very high, overlimiting beam current in no uniform cross section systems with dissipation. In this case two factors that lead to excitation of the beam wave with negative energy superimpose and this superposition results in instability of new type - dissipative instability of overlimiting electron beam. Physics of this instability in no uniform cross section system sharply differs from that in uniform cross section system. The growth rate of presented instability has more critical dependence on dissipation. (author)

  9. Transformation of the beam intensity distribution and formation of a uniform ion beam by means of nonlinear focusing

    International Nuclear Information System (INIS)

    Avoiding undesirable thermal stress or damage of a target vessel is an essential subject in high-intensity beam irradiation for accelerator-driven neutron production. A promising method to tailor the transverse beam intensity distribution for uniform beam irradiation on the target is the use of multipole magnets. We, therefore, study the transformation and uniformization of the transverse intensity distribution by means of nonlinear focusing induced from multipole magnets. It is theoretically described how the intensity distribution is transformed and made uniform by the nonlinear focusing force. Large-area uniform proton and heavy-ion beams are experimentally formed using octupole magnets at the azimuthally-varying-field cyclotron in Japan Atomic Energy Agency. (author)

  10. Proposals for the generation of angular momentum from non-uniformly polarized beams

    Science.gov (United States)

    Alonso, Mara; Piquero, Gemma; Serna, Julio

    2012-04-01

    Several optical arrangements using non-uniformly polarized fields are proposed for generating beams with spin and/or orbital angular momentum. By choosing adequately the input beam polarization and the characteristics of the different proposed set-ups we can control the overall angular momentum of the output beam at will. The orbital angular momentum is analyzed with the beam moments theory and the spin term is evaluated using the averaged s3 Stokes parameter.

  11. Analysis on plastic properties of reactive powder concrete continuous beams reinforced with GFRP bars

    Institute of Scientific and Technical Information of China (English)

    LU Shan-shan; ZHENG Wen-zhong

    2010-01-01

    To study the plastic properties of reactive powder concrete continuous beams reinforced with GFRP bars,the calculation programs for moment redistribution coefficients are prepared by using nonlinear analysis methods such as moment-curvature,conjugate beam method and so on.By comparing the test results of existed FRP bars reinforced concrete continuous beams with simulation results,the accuracy of the calculation program is verified.Then 18 simulated GFRP bars reinforced reactive powder concrete continuous beams are selected whose change parameters are reinforcement ratio of mid-span and middle support.Through the nonlinear analysis of simulated beams,moment redistribution coefficients under mid-span concentrated loads,one-third point loads and uniformly distributed loads are obtained respectively.Thus the formula of moment redistribution coefficients is obtained by fitting moment redistribution coefficients and factors.The results show that the reactive powder concrete continuous beams reinforced with GFRP bars have good plastic properties.

  12. Non-uniformly polarized beams across their transverse profiles: an introductory study for undergraduate optics courses

    Science.gov (United States)

    Piquero, Gemma; Vargas-Balbuena, Javier

    2004-11-01

    We provide a simple theoretical study of beams non-uniformly polarized across their transverse sections which can be introduced in undergraduate optics courses. In order to generate such beams we propose to use a slightly convergent (or divergent) linearly and uniformly polarized beam impinging on an anisotropic uniaxial material with the beam propagation direction along the optic axis. Analytical expressions for the Jones vector, Stokes parameters, ellipticity and azimuth at each point of the transverse section, perpendicular to the propagation direction, are obtained at the output of this system. By means of these parameters a detailed description of the state of polarization across the transverse profile is given.

  13. Non-uniformly polarized beams across their transverse profiles: an introductory study for undergraduate optics courses

    Energy Technology Data Exchange (ETDEWEB)

    Piquero, Gemma; Vargas-Balbuena, Javier [Departamento de Optica, Facultad de Ciencias FIsicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2004-11-12

    We provide a simple theoretical study of beams non-uniformly polarized across their transverse sections which can be introduced in undergraduate optics courses. In order to generate such beams we propose to use a slightly convergent (or divergent) linearly and uniformly polarized beam impinging on an anisotropic uniaxial material with the beam propagation direction along the optic axis. Analytical expressions for the Jones vector, Stokes parameters, ellipticity and azimuth at each point of the transverse section, perpendicular to the propagation direction, are obtained at the output of this system. By means of these parameters a detailed description of the state of polarization across the transverse profile is given.

  14. On Uniform Decay of Solutions for Extensible Beam Equation with Strong Damping

    Institute of Scientific and Technical Information of China (English)

    FENG Bao-wei; ZHANG Ming; LIANG Tie-wang; LI Hai-yan

    2014-01-01

    This paper investigates the existence and uniform decay of global solutions to the initial and boundary value problem with clamped boundary conditions for a nonlinear beam equation with a strong damping.

  15. Parametric characterization of non-uniformly polarized beams

    Science.gov (United States)

    Movilla, J. M.; Piquero, G.; Martínez-Herrero, R.; Mejías, P. M.

    1998-04-01

    A new overall parameter is defined, namely, the generalized degree of polarization, which involves the spatial distribution of the polarization of a light beam. This parameter is introduced on the basis of a general treatment recently proposed [Optics Lett. 22 (1997) 206] to characterize partially polarized fields, which extends the Stokes-Mueller formalism to describe the intensity moments of a quasimonochromatic beam. The main properties and the physical meaning of this parameter with regard to the spatial inhomogeneities of the polarization state are analysed, and a general measurement procedure is proposed.

  16. Improve large area uniformity and production capacity of laser interference lithography with beam flattening device

    Science.gov (United States)

    Yang, Yin-Kuang; Wu, Yu-Xiang; Lin, Te-Hsun; Yu, Chun-Wen; Fu, Chien-Chung

    2016-03-01

    Laser interference lithography (LIL) is a maskless lithography technique with many advantages such as simple optical design, inexpensive, infinite depth of focus, and large area patterning with single exposure. However, the intensity of normal laser beam is Gaussian distribution. In order to obtain large area uniform structure, we have to expand the laser beam much bigger than the wafer and use only the center part of the beam. Resulting in wasting lots of energy and the production capacity decrease. In this study, we designed a beam shaping device which consists of two parallel fused silicon optical window with different coating on both side. Two optical window form an air thin film. When the expanded laser beam pass through the device, the beam will experience many refraction and reflection between two optical window and interference with each other. The transmittance of laser beam will depend on the incident angle. The output intensity distribution will change from Gaussian distribution to a flat top distribution. In our experiment, we combined the beam shaping device with a Lloyd's mirror LIL system. Experiment results indicated that the LIL system with beam shaping device can obtain large area uniform pattern. And compare with the traditional Lloyd's mirror LIL system, the exposure time is shorten up to 4.5 times. In conclusion, this study design a beam flattening device for LIL system. The flat top beam can improve the large area uniformity and the production capacity of LIL. Making LIL more suitable for industry application.

  17. Uniform irradiation of high-energy intense ion beams to large area by two-dimensional beam scanning

    International Nuclear Information System (INIS)

    JAERI AVF cyclotron is equipped with ion beam scanners for large area irradiation. The cyclotron beam is two-dimensionally scanned by using a pair of laminated electromagnets. Cellulose triacetate (CTA) film dosimeter has been successfully applied as an integral method to measurement of the two-dimensional relative fluence distributions of the scanned ion beams, proton, He, C, Ar and Kr. The measured result showed that the fluence was not uniform within the scanned area. We have developed a beam scanning simulator to evaluate fluence distribution by calculation, and the simulation result was compared with the measured distribution. The un-uniformity was found to result from the distortion of the current wave form of the scanner. On the basis of this result, the power supply of the scanner was improved. A good uniformity of fluence distribution was available within ±4%. (author)

  18. An optical system to transform the output beam of a quantum cascade laser to be uniform

    Science.gov (United States)

    Jacobson, Jordan M.

    Quantum cascade lasers (QCLs) are a candidate for calibration sources in space-based remote sensing applications. However, the output beam from a QCL has some characteris- tics that are undesirable in a calibration source. The output beam from a QCL is polarized, both temporally and spatially coherent, and has a non-uniform bivariate Gaussian prole. These characteristics need to be mitigated before QCLs can be used as calibration sources. This study presents the design and implementation of an optical system that manipulates the output beam from a QCL so that it is spatially and angularly uniform with reduced coherence and polarization. (85 pages).

  19. Linear elastic analysis of thin laminated beams with uniform and symmetric cross-section

    OpenAIRE

    Zajíček M.

    2008-01-01

    This paper deals with analyses of linear elastic thin beams which are consisted of the homogeneous orthotropic layers. The cross-sections of these beams are assumed uniform and symmetric. Governing equations of one-dimensional model are derived on the base of the Timoshenko's beam theory. An evaluation of shear correction factor consists in conservation of the shear strain energy. This factor is calculated in this paper but only in the cases of the static problem. The general static solution ...

  20. Bending and rotational behaviour of semi-continuous composite beams

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Stresses and deflections were measured in various semi-continuous composite beams.The bending and rotational capacities of the composite connections were measured in terms of beam curvatures and deflections by using two full-scale semi-rigid composite frames with monotonic loadings.The effect of semi-rigid connections on the performance of composite beams with various loadings was compared with predictions and codes.The tests show that the semi-continuous composite beams are more economic and effective than the simple or continuous composite beams.The semi-rigid connections affect the bending capacities and beam deflections,so the connection behavior should be considered in the design of composite beams.Yielding analysis of the steel beam bottom flange has some influence on the deflection calculation of composite beams.

  1. High illumination uniformity scheme with 32 beams configuration for direct-drive inertial confinement fusion

    Science.gov (United States)

    Li, Li; Gu, Chun; Xu, Lixin; Zhou, Shenlei

    2016-04-01

    The self-adapting algorithms are improved to optimize a beam configuration in the direct drive laser fusion system with the solid state lasers. A configuration of 32 laser beams is proposed for achieving a high uniformity illumination, with a root-mean-square deviation at 10-4 level. In our optimization, the parameters such as beam number, beam arrangement, and beam intensity profile are taken into account. The illumination uniformity robustness versus the parameters such as intensity profile deviations, power imbalance, intensity profile noise, the pointing error, and the target position error is also discussed. In this study, the model is assumed a solid-sphere illumination, and refraction effects of incident light on the corona are not considered. Our results may have a potential application in the design of the direct-drive laser fusion of the Shen Guang-II Upgrading facility (SG-II-U, China).

  2. Free Vibration Analysis for Cracked FGM Beams by Means of a Continuous Beam Model

    OpenAIRE

    E Chuan Yang; Xiang Zhao; Ying Hui Li

    2015-01-01

    Based on Euler-Bernoulli beam theory and a continuous stiffness beam model, the free vibration of rectangular-section beams made of functionally graded materials (FGMs) containing open edge cracks is studied. Assuming the material gradients follow exponential distribution along beam thickness direction, the conversion relation between the vibration governing equations of a FGM beam and that of an isotropic homogenous beam is deduced. A continuous function is used to characterize the bending s...

  3. Overall parameters for the characterization of non-uniformly totally polarized beams

    Science.gov (United States)

    Martínez-Herrero, R.; Mejías, P. M.; Piquero, G.

    2006-09-01

    Several overall parameters are introduced to characterize the linear or circular polarization content of a non-uniformly totally polarized beam over the region of its wavefront where the irradiance is significant. These figures of merit are determined from the values of the Stokes parameters. The physical meaning of the proposed parameters is tested by computing some numerical examples, and their measurability is checked by considering non-uniformly totally polarized fields generated after propagation through uniaxial anisotropic materials.

  4. Free vibration analysis of a robotic fish based on a continuous and non-uniform flexible backbone with distributed masses

    Science.gov (United States)

    Coral, W.; Rossi, C.; Curet, O. M.

    2015-12-01

    This paper presents a Differential Quadrature Element Method for free transverse vibration of a robotic fish based on a continuous and non-uniform flexible backbone with distributed masses (fish ribs). The proposed method is based on the theory of a Timoshenko cantilever beam. The effects of the masses (number, magnitude and position) on the value of natural frequencies are investigated. Governing equations, compatibility and boundary conditions are formulated according to the Differential Quadrature rules. The convergence, efficiency and accuracy are compared to other analytical solution proposed in the literature. Moreover, the proposed method has been validate against the physical prototype of a flexible fish backbone. The main advantages of this method, compared to the exact solutions available in the literature are twofold: first, smaller computational cost and second, it allows analysing the free vibration in beams whose section is an arbitrary function, which is normally difficult or even impossible with other analytical methods.

  5. Laser-cooled continuous ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Schiffer, J.P.; Hangst, J.S.; Nielsen, J.S. [and others

    1995-08-01

    A collaboration with a group in Arhus, Denmark, using their storage ring ASTRID, brought about better understanding of ion beams cooled to very low temperatures. The longitudinal Schottky fluctuation noise signals from a cooled beam were studied. The fluctuation signals are distorted by the effects of space charge as was observed in earlier measurements at other facilities. However, the signal also exhibits previously unobserved coherent components. The ions` velocity distribution, measured by a laser fluorescence technique suggests that the coherence is due to suppression of Landau damping. The observed behavior has important implications for the eventual attainment of a crystalline ion beam in a storage ring. A significant issue is the transverse temperature of the beam -- where no direct diagnostics are available and where molecular dynamics simulations raise interesting questions about equilibrium.

  6. The uniform continuity of characteristic function from convoluted exponential distribution with stabilizer constant

    Science.gov (United States)

    Devianto, Dodi

    2016-02-01

    It is constructed convolution of generated random variable from independent and identically exponential distribution with stabilizer constant. The characteristic function of this distribution is obtained by using Laplace-Stieltjes transform. The uniform continuity property of characteristic function from this convolution is obtained by using analytical methods as basic properties.

  7. Numerical analysis of reinforced concrete continuous deep beams

    OpenAIRE

    Asin, M.; Walraven, J.

    1995-01-01

    The structural behaviour of deep beams is still not completely understood, since, for example, plane sections do not remain plane and no uniform shear flow can develop because of the small ratio between depth and shear span. If in addition, the supporting system is also statically indeterminate, the number of difficulties increases. In order to investigate the behaviour of statically indeterminate deep beams, a series of fourteen tests has been carried out. Variables were the slenderness, the...

  8. Low dimensional modeling of a non-uniform, buckled piezoelectric beam for vibrational energy harvesting

    Science.gov (United States)

    Van Blarigan, Louis; Moehlis, Jeff; McMeeking, Robert

    2015-06-01

    A model is developed for a non-uniform piezoelectric beam suitable for analyzing energy harvesting behavior. System dynamics are projected onto a numerically developed basis to produce energy functions which are used to derive equations of motion for the system. The resulting model reproduces the experimentally observed transition to chaos while providing a conservative estimate of power output and bandwidth.

  9. Numerical analysis of reinforced concrete continuous deep beams

    NARCIS (Netherlands)

    Asin, M.; Walraven, J.

    1995-01-01

    The structural behaviour of deep beams is still not completely understood, since, for example, plane sections do not remain plane and no uniform shear flow can develop because of the small ratio between depth and shear span. If in addition, the supporting system is also statically indeterminate, the

  10. A new thermoluminescence mixed order model for continuous and uniform distribution of trapping centers

    OpenAIRE

    M. Zahedifar; S Harooni

    2011-01-01

    A mixed order model is proposed for describing thermoluminescence (TL) glow peaks with continuous and uniform distribution of trapping states. It is shown that the presented function reduces to the simple known models at the limiting cases. The function for TL intensity has been introduced in terms of intensity and temperature of the peak maximum. These parameters can easily be estimated from the shape of the glow peak as initial guesstimate for the curve fitting procedure. Considering the di...

  11. Computer simulations for intense continuous beam transport in electrostatic lens systems

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiao-Song; L(U) Jian-Qin

    2008-01-01

    A code LEADS based on the Lie algebraic analysis for the continuous beam dynamics with space charge effect in beam transport has been developed.The program is used for the simulations of axial-symmetric and unsymmetricalintense continuous beam in the channels including drift spaces.electrostatic lenses and DC electrostatic accelerating tubes.In order to get the accuracy required,all elements are divided into many small segments,and the electric field in the segments is regarded as uniform field,and the dividing points are treated as thin lenses.Iteration procedures are adopted in the program to obtain self-consistent solutions.The code can be used in the designs of low energy beam transport systems,electrostatic accelerators and ion implantation machines.

  12. Growth of a Gaussian ripple on a uniform beam in a magnetoplasma

    International Nuclear Information System (INIS)

    This paper presents an investigation of the growth of a Gaussian ripple superimposed on a uniform beam propagating along the static magnetic field in a magnetoplasma. The differential equation for beam width parameter of the ripple has been written by following Sodha et al (Prog. Optics; 13: 171 (1976)) and its numerical solution has been obtained by the Runga Kutta method. Two modes of propagation of the ripple exist, viz. extraordinary and ordinary, and the critical power for focusing is also different for the two modes. The ripple becomes focused when the initial power of the ripple is greater than the critical power for focusing. The focusing is also considerably affected by the power of the main beam, the strength of the magnetic field and the phase angle between the electric vectors of the main beam and the ripple. (author)

  13. Parametric characterization of the spatial structure of non-uniformly polarized laser beams

    Science.gov (United States)

    Mejías, P. M.; Martínez-Herrero, R.; Piquero, G.; Movilla, J. M.

    We present an approach for describing the spatial structure of partially polarized light fields. Unlike the treatments usually encountered in the literature, in which the polarization state is represented by position-dependent functions, the formalism shown here characterizes the polarization by means of a family of measurable overall parameters averaged over the transverse spatial region where the beam intensity reaches significant values. Generalized degrees of polarization are introduced to evaluate the uniformity of the spatial distribution of the polarization state of the beam-like field. The possibility of improvement and optimization of the quality of a polarized laser beam (understood as the general usefulness of such field for collimation and focussing) is analyzed by employing first-order optical systems. Finally, attention is briefly devoted to non-paraxial electromagnetic vector beams, whose parametric description of their polarization properties constitutes, at present, a challenge for theoreticians.

  14. Ultrafast laser parallel microprocessing using high uniformity binary Dammann grating generated beam array

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, Zheng, E-mail: kz518@msn.com [Laser Group, Centre for Material and Structures, School of Engineering, University of Liverpool, Brownlow Street, Liverpool L69 3GQ (United Kingdom); Perrie, Walter; Liu, Dun; Edwardson, Stuart P.; Jiang, Yao; Fearon, Eamonn; Watkins, Ken G.; Dearden, Geoff [Laser Group, Centre for Material and Structures, School of Engineering, University of Liverpool, Brownlow Street, Liverpool L69 3GQ (United Kingdom)

    2013-05-15

    Ultrafast laser parallel processing using diffractive multi-beam patterns generated by a spatial light modulator (SLM) has demonstrated a great increase in processing throughput and efficiency. Applications ranging from surface thin film patterning to internal 3D refractive index modification have been recently reported with the parallel processing technology. Periodic and symmetrical geometry design (e.g. N × M beam array) of the multi-beam pattern must be avoided to guarantee the required high uniformity in these applications, which, however, limited the processing flexibility. In this paper, Dammann gratings are used to create diffractive 1 × 5 and 5 × 5 beam arrays for the parallel processing. The 0-th order, observed slightly stronger than the other higher orders, can be adjusted by superimposing a Fresnel zone lens (FZL) and tuning the degree of defocusing at the processing plane. The uniformity (presented by the variation of the machined hole diameter) is measured to be <4% after the adjustment. Additionally, a parallel surface patterning of indium tin oxide (ITO) thin film with periodic array structures was demonstrated using the Dammann grating generated beam array without requiring the complicated geometry separation and the time-consuming positioning.

  15. Beam Focusing by a Non-Uniformly-Spaced Nanoslit Array in a Metallic Film

    Institute of Scientific and Technical Information of China (English)

    JIAO Xiao-Jin; WANG Pei; ZHANG Dou-Guo; LU Yong-Hua; XIE Jian-Ping; MING Hai

    2006-01-01

    @@ A finite difference time domain simulation has been performed to analyse the optical transmission through a non-uniformly-spaced nanoslit array in silver film. The phase change of surface plasmons propagating on the silver film is used to modulate the initial phase of the output beam. The beam deflection and focusing function are designed, and the focal depth of the focusing metallic structure are mainly considered. It is found that the focal depth can be controlled by altering the effective width of this structure, i.e. the number of slits, when the relative spacing is fixed.

  16. Marking of welded pieces using continuous or pulse electron beam

    Czech Academy of Sciences Publication Activity Database

    Zobač, Martin

    Varna: Institute of Electronic s BAS, 2003, s. 191 - 197. [EBT 2003. Varna (BG), 01.06.2003-06.06.2003] R&D Projects: GA AV ČR IBS2065015 Institutional research plan: CEZ:AV0Z2065902 Keywords : continuous electron beam * pulse electron beam * material surface Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. Thin films' thickness uniformity associated with the method of electron beam evaporation

    Science.gov (United States)

    Xia, Zhilin; Xue, Yiyu; Guo, Peitao; Li, Zhangwang

    2009-08-01

    Coating material has been considered as being made up of a lot of small tablets. These tablets have plane surface during the whole film preparation process. Based on the assumption that a column etching pit will form in coating material when electron beam is used for heating, influences of the etching pit's dimension and the internal structure of the vacuum chamber on films thickness uniformity have been investigated. Results reflect that the appearance of etching pit does not always cause negative influence on films thickness uniformity. The negative impact of etching on films thickness uniformity can be reduced by optimizing the internal structure of the vacuum chamber and preparation technical parameters. But, it is difficult to achieve the beneficial action. This investigation is useful to help us understand physical meaning of the emission characteristics of the evaporation particle and design experimental scheme.

  18. Beam uniformization and low frequency RF cavities in compact electron storage rings

    Science.gov (United States)

    Pham, Alfonse N.

    An electron storage ring is currently under construction at Indiana University for extreme environment radiation effects experiments, x-ray production, and particle beam dynamics experiments. For an electron bunch to be successfully stored for long durations, a radio-frequency (RF) resonant structure will be used to provide an adequate RF bucket for longitudinal focusing and replenishment of energy electrons loses via synchrotron radiation. Due to beam line space limitation that are inherent to compact circular particle accelerators, a unique ferrite-loaded quarter-wave RF resonant cavity has been designed and constructed for use in the electron storage ring. The physics of particle accelerators and beams, ferrite-loaded RF resonant cavity theory, and results of the Poisson-SUPERFISH electromagnetic field simulations that were used to guide the specification and design of the RF cavity will be presented. Low-power resonant cavity characterization measurements were used to benchmark the performance of the RF cavity. High-power characterization and measurements with electron beams will be used to validate the performance of the cavity in the electron storage ring. To fulfill the requirements for radiation effect experiments, the storage ring manipulation of beams that utilizes a phase space beam dilution method have been developed for the broadening of the radiation damped electron bunch with longitudinal particle distribution uniformity. The method relies on phase modulation applied to a double RF system to generate large regions of bounded chaotic particle motion in phase space. These region are formed by a multitude of overlapping parametric resonances. Parameters of the double RF system and applied phase modulation can be adjusted to vary the degree of beam dilution. The optimal RF parameters have been found for maximal bunch broadening, uniform longitudinal particle distribution, and bounded particle diffusion. Implementation of the phase space dilution method

  19. Production of uniform ion beam of large area in a magnetically-insulatd diode

    International Nuclear Information System (INIS)

    The results of experimental investigation of a magnetically insulated diode generating a powerful ribbon ion beam with 100x10 cm cross section are presented. Modification of the known diode designs allowed to provide the constancy of the electric and magnetic field by the anode length and uniform generation of the ion beam over the larger part of its length. At the same time these measures have decreased considerably electron losses in the anode up to 1-2 A/cm2 that reduces the efficiency of anode plasma formation during the first part of a high-voltage pulse. At 500 kV anode voltage the ion current amplitude is 18 kA, the beam-out energy - 460 J, the efficiency of ion generation - 85%

  20. Ion beam induced charge and cathodoluminescence imaging of response uniformity of CVD diamond radiation detectors

    CERN Document Server

    Sellin, P J; Galbiati, A; Maghrabi, M; Townsend, P D

    2002-01-01

    The uniformity of response of CVD diamond radiation detectors produced from high quality diamond film, with crystallite dimensions of >100 mu m, has been studied using ion beam induced charge imaging. A micron-resolution scanning alpha particle beam was used to produce maps of pulse height response across the device. The detectors were fabricated with a single-sided coplanar electrode geometry to maximise their sensitivity to the surface region of the diamond film where the diamond crystallites are highly ordered. High resolution ion beam induced charge images of single crystallites were acquired that demonstrate variations in intra-crystallite charge transport and the termination of charge transport at the crystallite boundaries. Cathodoluminescence imaging of the same crystallites shows an inverse correlation between the density of radiative centres and regions of good charge transport.

  1. Constrained Single Period Stochastic Uniform Inventory Model With Continuous Distributions of Demand and Varying Holding Cost

    Directory of Open Access Journals (Sweden)

    Hala A. Fergany

    2006-01-01

    Full Text Available This paper derives the single period stochastic inventory model with continuous distributions of demand and the holding unit cost is a function of the purchased (ordered quantity. The objective is to find the optimal purchased quantity which minimizes the expected total cost for the period under a restriction on the expected varying holding cost when the demand during the period follows the uniform, the exponential and the Laplace distributions, using the Lagrange multiplier approach. Some special cases are deduced and illustrative numerical examples with some graphs are added.

  2. ON THE UNIFORM STRONG APPROXIMATION OF MARCINKIEWICZ TYPE FOR MULTIVARIABLE CONTINUOUS FUNCTIONS

    Institute of Scientific and Technical Information of China (English)

    Yujun Zhang; Xiaoyuan He

    2005-01-01

    The rate of uniform strong approximation of Marcinkiewicz type for multivariable continuous func-tions is obtained in this paper as follows:‖1/k+1 k∑j=0|Sj(f)- f|q‖≤C/k +1 k∑j=0 Eqj(f),where Sj (f) denotes the square partial Fourier sum of f and Ej (f) denotes the square best approximation of f by trigonometric polynomials of degree (j, j, … ,j),j = 0,1, 2,….

  3. Apparatus and methods for continuous beam fourier transform mass spectrometry

    Science.gov (United States)

    McLuckey, Scott A.; Goeringer, Douglas E.

    2002-01-01

    A continuous beam Fourier transform mass spectrometer in which a sample of ions to be analyzed is trapped in a trapping field, and the ions in the range of the mass-to-charge ratios to be analyzed are excited at their characteristic frequencies of motion by a continuous excitation signal. The excited ions in resonant motions generate real or image currents continuously which can be detected and processed to provide a mass spectrum.

  4. A new thermoluminescence mixed order model for continuous and uniform distribution of trapping centers

    Directory of Open Access Journals (Sweden)

    M Zahedifar

    2011-06-01

    Full Text Available A mixed order model is proposed for describing thermoluminescence (TL glow peaks with continuous and uniform distribution of trapping states. It is shown that the presented function reduces to the simple known models at the limiting cases. The function for TL intensity has been introduced in terms of intensity and temperature of the peak maximum. These parameters can easily be estimated from the shape of the glow peak as initial guesstimate for the curve fitting procedure. Considering the direct relation between the parameters entered in the proposed model and the physics of TL phenomenon, it is deduced that it is more appropriate for describing TL peaks with continuous distribution of trapping states.

  5. Continuous guided beams of slow and internally cold polar molecules

    CERN Document Server

    Sommer, Christian; Motsch, Michael; Pohle, Sebastian; Bayerl, Josef; Pinkse, Pepijn W H; Rempe, Gerhard

    2008-01-01

    We describe the combination of buffer-gas cooling with electrostatic velocity filtering to produce a high-flux continuous guided beam of internally cold and slow polar molecules. In a previous paper (L.D. van Buuren et al., arXiv:0806.2523v1) we presented results on density and state purity for guided beams of ammonia and formaldehyde using an optimized set-up. Here we describe in more detail the technical aspects of the cryogenic source, its operation, and the optimization experiments that we performed to obtain best performance. The versatility of the source is demonstrated by the production of guided beams of different molecular species.

  6. SU-E-T-304: Study of Secondary Neutrons From Uniform Scanning Proton Beams

    International Nuclear Information System (INIS)

    Purpose: Secondary neutrons are unwanted byproducts from proton therapy and exposure from secondary radiation during treatment could increase risk of developing a secondary cancer later in a patient's lifetime. The purpose of this study is to investigate secondary neutrons from uniform scanning proton beams under various beam conditions using both measurements and Monte Carlo simulations. Methods: CR-39 Plastic Track Nuclear Detectors (PNTD) were used for the measurement. CR-39 PNTD has tissue like sensitivity to the secondary neutrons but insensitive to the therapeutic protons. In this study, we devised two experimental conditions: a) hollow-phantom; phantom is bored with a hollow cylinder along the direction of the beam so that the primary proton passes through the phantom without interacting with the phantom material, b) cylindrical-phantom; a solid cylinder of diameter close to the beam diameter is placed along the beam path. CR-39 PNTDs were placed laterally inside a 60X20X35 cm3 phantom (hollow-phantom) and in air (cylindrical-phantom) at various angles with respect to the primary beam axis. We studied for three different proton energies (78 MeV, 162 MeV and 226 MeV), using a 4 cm modulation width and 5cm diameter brass aperture for the entire experiment and simulation. A comparison of the experiment was performed using the Monte Carlo code FLUKA. Results: The measured secondary neutron dose equivalent per therapeutic primary proton dose (H/D) ranges from 2.1 ± 0.2 to 25.42 ± 2.3 mSv/Gy for the hollow phantom study, and 2.7 ± 0.3 to 46.4 ± 3.4 mSv/Gy for the cylindrical phantom study. Monte Carlo simulations predicated neutron dose equivalent from measurements within a factor of 5. Conclusion: The study suggests that the production of external neutrons is significantly higher than the production of internal neutrons

  7. CEBAF [Continuous Electron Beam Accelerator Facility] design report

    International Nuclear Information System (INIS)

    This book describes the conceptual design of, and the planning for, the Continuous Electron Beam Accelerator Facility (CEBAF), which will be a high-intensity, continuous-wave electron linear accelerator (linac) for nuclear physics. Its principal scientific goal is to understand the quark structure, behavior, and clustering of individual nucleons in the nuclear medium, and simultaneously to understand the forces governing this behavior. The linac will consist of 1 GeV of accelerating structure, split into two antiparallel 0.5-GeV segments. The segments will be connected by a beam transport system to circulate the electron beams from one segment to the other for up to four complete passes of acceleration. The maximum beam energy will be 4 GeV at a design current of 200 microamperes. The accelerator complex will also include systems to extract three continuous beams from the linac and to deliver them to three experimental halls equipped with detectors and instrumentation for nuclear physics research. The accelerating structure will be kept superconducting within insulated cryostats filled with liquid helium produced at a central helium refrigerator and distributed to the cryostats via insulated transfer lines. An injector, instrumentation and controls for the accelerator, radio-frequency power systems, and several support facilities will also be provided. A cost estimate based on the Work Breakdown Structure has been completed. Assuming a five-year construction schedule starting early in FY 1987, the total estimated cost is $236 million (actual year dollars), including contingency

  8. SU-E-T-542: Measurement of Internal Neutrons for Uniform Scanning Proton Beams

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M; Ahmad, S [University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Zheng, Y; Rana, S [Procure Proton Therapy Center, Oklahoma City, OK (United States); Collums, T [University of Iowa Hospitals and Clinics, Iowa City, IA (United States); Monsoon, J; Benton, E [Oklahoma State University, Stillwater, OK (United States)

    2015-06-15

    Purpose: In proton radiotherapy, the production of neutrons is a wellknown problem since neutron exposure can lead to increased risk of secondary cancers later in the patient’s lifetime. The assessment of neutron exposure is, therefore, important for the overall quality of proton radiotherapy. This study investigates the secondary neutrons created inside the patient from uniform scanning proton beams. Methods: Dose equivalent due to secondary neutrons was measured outside the primary field as a function of distance from beam isocenter at three different angles, 45, 90 and 135 degree, relative to beam axis. Plastic track nuclear detector (CR-39 PNTD) was used for the measurement of neutron dose. Two experimental configurations, in-air and cylindrical-phantom, were designed. In a cylindrical-phantom configuration, a cylindrical phantom of 5.5 cm diameter and 35 cm long was placed along the beam direction and in an in-air configuration, no phantom was used. All the detectors were placed at nearly identical locations in both configurations. Three proton beams of range 5 cm, 18 cm, and 32 cm with 4 cm modulation width and a 5 cm diameter aperture were used. The contribution from internal neutrons was estimated from the differences in measured dose equivalent between in-air and cylindrical-phantom configurations at respective locations. Results: The measured ratio of neutron dose equivalent to the primary proton dose (H/D) dropped off with distance and ranged from 27 to 0.3 mSv/Gy. The contribution of internal neutrons near the treatment field edge was found to be up to 64 % of the total neutron exposure. As the distance from the field edge became larger, the external neutrons from the nozzle appear to dominate and the internal neutrons became less prominent. Conclusion: This study suggests that the contribution of internal neutrons could be significant to the total neutron dose equivalent.

  9. SU-E-T-542: Measurement of Internal Neutrons for Uniform Scanning Proton Beams

    International Nuclear Information System (INIS)

    Purpose: In proton radiotherapy, the production of neutrons is a wellknown problem since neutron exposure can lead to increased risk of secondary cancers later in the patient’s lifetime. The assessment of neutron exposure is, therefore, important for the overall quality of proton radiotherapy. This study investigates the secondary neutrons created inside the patient from uniform scanning proton beams. Methods: Dose equivalent due to secondary neutrons was measured outside the primary field as a function of distance from beam isocenter at three different angles, 45, 90 and 135 degree, relative to beam axis. Plastic track nuclear detector (CR-39 PNTD) was used for the measurement of neutron dose. Two experimental configurations, in-air and cylindrical-phantom, were designed. In a cylindrical-phantom configuration, a cylindrical phantom of 5.5 cm diameter and 35 cm long was placed along the beam direction and in an in-air configuration, no phantom was used. All the detectors were placed at nearly identical locations in both configurations. Three proton beams of range 5 cm, 18 cm, and 32 cm with 4 cm modulation width and a 5 cm diameter aperture were used. The contribution from internal neutrons was estimated from the differences in measured dose equivalent between in-air and cylindrical-phantom configurations at respective locations. Results: The measured ratio of neutron dose equivalent to the primary proton dose (H/D) dropped off with distance and ranged from 27 to 0.3 mSv/Gy. The contribution of internal neutrons near the treatment field edge was found to be up to 64 % of the total neutron exposure. As the distance from the field edge became larger, the external neutrons from the nozzle appear to dominate and the internal neutrons became less prominent. Conclusion: This study suggests that the contribution of internal neutrons could be significant to the total neutron dose equivalent

  10. Simulation and Experimental Investigations on the Strain Measurement of the Uniform Strength Beam Using a FBG sensor

    International Nuclear Information System (INIS)

    The model of force analysis on a uniform strength beam is built by the general finite element program (ANSYS software). The flexivity profile produced by uniform strength beam with different forces is simulated by ANSYS software. In experiment, a fiber Bragg grating sensor is fixed on the uniform strength beam with modified acrylate. The flexivity and strain are varied by changing the load on the end of the beam. The strain of the uniform strength beam is measured with FBG when applied force is varied from 2.45N to14.7N with a step of 2.45N. Both the simulated and experimental results show that, the strain induced by the uniform strength beam is linear with the load force. The sensitivity is 18.32με/N for experimental measurement, and 19.72με/N for simulation. The experimental results are consistent with the simulation results, with the maximum measurement error of strain being 7.4%. It indicates that, the FBG sensor fixed with modified acrylate is proved to be effectively and reliably in the applications of civil engineering.

  11. THERMAL POST-BUCKLING OF AN ELASTIC BEAMS SUBJECTED TO A TRANSVERSELY NON-UNIFORM TEMPERATURE RISING

    Institute of Scientific and Technical Information of China (English)

    李世荣; 程昌钧; 周又和

    2003-01-01

    Based on the nonlinear geometric theory of axially extensible beams and by usingthe shooting method, the thermal post-buckling responses of an elastic beams, withimmovably simply supported ends and subjected to a transversely non-uniformly distributedtemperature rising, were investigated. Especially, the influences of the transversetemperature change on the thermal post-buckling deformations were examined and thecorresponding characteristic curves were plotted. The numerical results show that theequilibrium paths of the beam are similar to what of an initially deformed beam because ofthe thermal bending moment produced in the beam by the transverse temperature change.

  12. Uniform heating of materials into the warm dense matter regime with laser-driven quasi-monoenergetic ion beams

    CERN Document Server

    Bang, W; Bradley, P A; Vold, E L; Boettger, J C; Fernández, J C

    2015-01-01

    In a recent experiment on the Trident laser facility, a laser-driven beam of quasi-monoenergetic aluminum ions was used to heat solid gold and diamond foils isochorically to 5.5 eV and 1.7 eV, respectively. Here theoretical calculations are presented that suggest the gold and diamond were heated uniformly by these laser-driven ion beams. According to calculations and SESAME equation-of-state tables, laser-driven aluminum ion beams achievable on Trident, with a finite energy spread of (delta E)/E ~ 20%, are expected to heat the targets more uniformly than a beam of 140 MeV aluminum ions with zero energy spread. The robustness of the expected heating uniformity relative to the changes in the incident ion energy spectra is evaluated, and expected plasma temperatures of various target materials achievable with the current experimental platform are presented.

  13. Exact Reconstruction From Uniformly Attenuated Helical Cone-Beam Projections in SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Gullberg, Grant T; Huang, Qiu; You, Jiangsheng; Zeng, Gengsheng L.

    2008-12-18

    In recent years the development of cone-beam reconstruction algorithms has been an active research area in x-ray computed tomography (CT), and significant progress has been made in the advancement of algorithms. Theoretically exact and computationally efficient analytical algorithms can be found in the literature. However, in single photon emission computed tomography (SPECT), published cone-beam reconstruction algorithms are either approximate or involve iterative methods. The SPECT reconstruction problem is more complicated due to degradations in the imaging detection process, one of which is the effect of attenuation of gamma ray photons. Attenuation should be compensated for to obtain quantitative results. In this paper, an analytical reconstruction algorithm for uniformly attenuated cone-beam projection data is presented for SPECT imaging. The algorithm adopts the DBH method, a procedure consisting of differentiation and backprojection followed by a finite inverse cosh-weighted Hilbert transform. The significance of the proposed approach is that a selected region of interest can be reconstructed even with a detector with a reduced field of view. The algorithm is designed for a general trajectory. However, to validate the algorithm, a numerical study was performed using a helical trajectory. The implementation is efficient and the simulation result is promising.

  14. Exact Reconstruction From Uniformly Attenuated Helical Cone-Beam Projections in SPECT

    International Nuclear Information System (INIS)

    In recent years the development of cone-beam reconstruction algorithms has been an active research area in x-ray computed tomography (CT), and significant progress has been made in the advancement of algorithms. Theoretically exact and computationally efficient analytical algorithms can be found in the literature. However, in single photon emission computed tomography (SPECT), published cone-beam reconstruction algorithms are either approximate or involve iterative methods. The SPECT reconstruction problem is more complicated due to degradations in the imaging detection process, one of which is the effect of attenuation of gamma ray photons. Attenuation should be compensated for to obtain quantitative results. In this paper, an analytical reconstruction algorithm for uniformly attenuated cone-beam projection data is presented for SPECT imaging. The algorithm adopts the DBH method, a procedure consisting of differentiation and backprojection followed by a finite inverse cosh-weighted Hilbert transform. The significance of the proposed approach is that a selected region of interest can be reconstructed even with a detector with a reduced field of view. The algorithm is designed for a general trajectory. However, to validate the algorithm, a numerical study was performed using a helical trajectory. The implementation is efficient and the simulation result is promising

  15. Structural vibration a uniform accurate solution for laminated beams, plates and shells with general boundary conditions

    CERN Document Server

    Jin, Guoyong; Su, Zhu

    2015-01-01

    This book develops a uniform accurate method which is capable of dealing with vibrations of laminated beams, plates and shells with arbitrary boundary conditions including classical boundaries, elastic supports and their combinations. It also provides numerous solutions for various configurations including various boundary conditions, laminated schemes, geometry and material parameters, which fill certain gaps in this area of reach and may serve as benchmark solutions for the readers. For each case, corresponding fundamental equations in the framework of classical and shear deformation theory are developed. Following the fundamental equations, numerous free vibration results are presented for various configurations including different boundary conditions, laminated sequences and geometry and material properties. The proposed method and corresponding formulations can be readily extended to static analysis.

  16. Unique determination of a single crack in a uniform simply supported beam in bending vibration

    Science.gov (United States)

    Fernández-Sáez, José; Morassi, Antonino; Pressacco, Martina; Rubio, Lourdes

    2016-06-01

    In this paper we consider one of the basic inverse problems in damage detection based on natural frequency data, namely the identification of a single open crack in a uniform simply supported beam from measurement of the first and the second natural frequency. It is commonly accepted in the literature that the knowledge of this set of spectral data allows for the unique determination of the severity and the position (up to symmetry) of the damage. However, in spite of the fact that many numerical evidences are in support of this property, the result is rigorously proved only when the severity of the crack is small. In this paper we definitely show, by means of an original constructive method, that the above result holds true for any level of crack severity.

  17. CEBAF [Continuous Electron Beam Accelerator Facility] scientific program

    International Nuclear Information System (INIS)

    The principal scientific mission of the Continuous Electron Beam Facility (CEBAF) is to study collective phenomena in cold (or normal) nucler matter in order to understand the structure and behavior of macroscopic systems constructed from nuclei. This document discusses in broad popular terms those issues which the CEBAF experimental and theoretical program are designed to address. Specific experimental programs currently planned for CEBAF are also reivewed. 35 refs., 19 figs

  18. Environmental assessment: Continuous Electron Beam Accelerator Facility, Newport News, Virginia

    International Nuclear Information System (INIS)

    This Environmental Assessment has been prepared by the US Department of Energy (DOE) to fulfill its obligations pursuant to Sect. 102 of the National Environmental Policy Act (NEPA) of 1969 (Public Law 91-190). The proposed federal action addressed in this document is DOE's funding of a Continuous Electron Beam Accelerator Facility (CEBAF) at Newport News, Virginia. DOE intends to contract with the Southeastern Universities Research Association (SURA) for operation of CEBAF, a continuous wave (CW) linear accelerator system (linac) capable of providing high-duty-factor beams throughout the energy range from 0.5 to 4.0 GeV. CEBAF will be the first of its kind worldwide and will offer a multi-GeV energy, high-intensity, high-duty-factor electron beam for use by the US nuclear physics community in research on the states of nuclear matter and the short-distance behavior of nuclei. The CEBAF project is largely in the conceptual design stage, with some components in the preliminary design stage. Construction is anticipated to begin in 1987 and be completed by 1992

  19. Lie map for the nonlinear transport of continuous intense beams in the axial-symmetric electrostatic fields

    Institute of Scientific and Technical Information of China (English)

    Jianqin Lü; Xiaosong Zhao

    2008-01-01

    Nonlinear transport of intense continuous beam in the axial-symmetric electrostatic fields is analyzed with the Lie algebraic method.The K-V particle distribution is adopted in the analysis. The results obtained can be used in the calculations of the intense continuous beam dynamics in the beam optical systems consisting of drift spaces, electrostatic lenses, and DC electrostatic accelerating tubes. A com-puter code has been designed for practical simulations. To meet the needs of accurate calculation, all the elements are divided into many small segments, the electric fields in each segment are regarded as uniform fields, and the dividing points are treated as thin lenses. Iter-ation procedures are adopted in the code to obtain self-consistent solutions. The code can be used to design low energy dc beam transport systems, electrostatic accelerators, and ion implantation machines.

  20. Continuous variable quantum communication with bright entangled optical beams

    Institute of Scientific and Technical Information of China (English)

    XIE Chang-de; ZHANG Jing; PAN Qing; JIA Xiao-jun; PENG Kun-chi

    2006-01-01

    In this paper,we briefly introduce the basic concepts and protocols of continuous variable quantum communication,and then summarize the experimental researches accomplished by our group in this field.The main features of quantum communication systems used in our experiments are:(1) The bright entangled optical beams with the anticorrelated amplitude quadratures and the correlated phase quadratures that serve as the entanglement resources and (2) The Bell-state direct detection systems are utilized in the measurements of quantum entanglement and transmitted signals instead of the usually balanced homodyne detectors.

  1. On the Heat Transfer through a Solid Slab Heated Uniformly and Continuously on One of Its Surfaces

    Science.gov (United States)

    Marin, E.; Lara-Bernal, A.; Calderon, A.; Delgado-Vasallo, O.

    2011-01-01

    Some peculiarities of the heat transfer through a sample that is heated by the superficial absorption of light energy under continuous uniform illumination are discussed. We explain, using a different approach to that presented in a recent article published in this journal (Salazar "et al" 2010 "Eur. J. Phys." 31 1053-9), that the front surface of…

  2. Acoustic Prism for Continuous Beam Steering Based on Piezoelectric Metamaterial

    CERN Document Server

    Xu, Jiawen

    2016-01-01

    This paper investigates an acoustic prism for continuous acoustic beam steering by a simple frequency sweep. This idea takes advantages of acoustic wave velocity shifting in metamaterials in the vicinity of local resonance. We apply this concept into the piezoelectric metamaterial consisting of host medium and piezoelectric LC shunt. Theoretical modeling and FEM simulations are carried out. It is shown that the phase velocity of acoustic wave changes dramatically in the vicinity of local resonance. The directions of acoustic wave can be adjusted continuously between 2 to 16 degrees by a simple sweep of the excitation frequency. Such an electro-mechanical coupling system has a feature of adjusting local resonance without altering the mechanical part of the system.

  3. Vibration Analysis of a Simply Supported Beam Traversed by Uniform Distributed Moving Load

    Institute of Scientific and Technical Information of China (English)

    Yu YANG; Nian-guan TENG; Yian-feng TENG

    2004-01-01

    Considering the engineering background of some transportation system like maglev, vertical vibration of the simply supported beam is investigated. The length of the vehicle is assumed to be longer than the beam span. The model of moving distributed load with constant speed is established .The beam can be taken as Euler-Bernoulli beam model and the right side of the control equation is simplified by using a moving status function. Duhamel integral and mode superposition method is used to solve the dynamic behavior of the beam. In this aspect deflection and acceleration are included. The results of different parameters such as the span of beam, velocity of load and ratio vehicle-Beam masses are compared. All results show that the dynamic response of the beam is tied up with these factors: the frequency of the beam, the moving frequency of the load and the ratio of vehicle-beam mass.

  4. Beam non-uniformity smoothing using density valley formed by heavy ion beam deposition in inertial confinement fusion fuel pellet

    International Nuclear Information System (INIS)

    We study the beam nonuniformity smoothing effect of radiation transport in the density valley formed by an ion-beam deposition in a heavy ion-beam inertial confinement fusion pellet by numerical simulations. The simulation results show that the radiation energy is confined in the density valley, and the beam nonuniformity can be smoothed out by the radiation transport along the density valley. In addition, an estimation for the Rayleigh-Taylor instability during the implosion phase is also presented. (author)

  5. Dosimetric measurements and Monte Carlo simulation for achieving uniform surface dose in pulsed electron beam irradiation facility

    Indian Academy of Sciences (India)

    V C Petwal; J N Rao; Jishnu Dwivedi; V K Senecha; K V Subbaiah

    2010-03-01

    A prototype pulsed electron beam irradiation facility for radiation processing of food and medical products is being commissioned at our centre in Indore, India. Analysis of surface dose and uniformity for a pulsed beam facility is of crucial importance because it is influenced by various operating parameters such as beam current, pulse repetition rate (PRR), scanning current profile and frequency, scanning width and product conveying speed. A large number of experiments are required to determine the harmonized setting of these operating parameters for achieving uniform dose. Since there is no readily available tool to set these parameters, use of Monte Carlo methods and computational tools can prove to be the most viable and time saving technique to support the assessment of the dose distribution. In the present study, Monte Carlo code, MCNP, is used to simulate the transport of 10 MeV electron beam through various mediums coming into the beam path and generate an equivalent dose profile in a polystyrene phantom for stationary state. These results have been verified with experimentally measured dose profile, showing that results are in good agreement within 4%. The Monte Carlo simulation further has been used to optimize the overlapping between the successive pulses of a scan to achieve ± 5% dose uniformity along the scanning direction. A mathematical model, which uses the stationary state data, is developed to include the effect of conveyor speed. The algorithm of the model is discussed and the results are compared with the experimentally measured values, which show that the agreement is better than 15%. Finally, harmonized setting for operating parameters of the accelerator are derived to deliver uniform surface dose in the range of 1–13 kGy/pass.

  6. Uniformity and continuity of effective strain in AZ91D processed by multi-pass equal channel angular extrusion

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-hua; LUO Shou-jing; DU Zhi-ming

    2008-01-01

    AZ91D magnesium alloy was processed by equal channel angular extrusion(ECAE). The influence of extrusion temperature, extrusion pass and extrusion route on the ultimate strength of the extruded billet was analyzed. The process of multi-pass extrusion was simulated with the method of finite element analysis, and the continuity and uniformity of effective strain in multi-pass extrusion were investigated. The results show that extrusion pass plays the most important role in improving the ultimate strength of AZ91D magnesium alloy, the extrusion route is the second, and the extrusion temperature is the last. From the numerical simulation, there exists the continuity of the accumulated deformation in multi-pass extrusion and the effective strain increases linearly. The tendency of the strain uniformity is different in multi-pass extrusion with extrusion routes. The results of experiment agree with those of numerical simulation.

  7. MHD flow and heat transfer from continuous surface in uniform free stream of non-Newtonian fluid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An analysis is carried out to study the steady flow and heat transfer characteristics from a continuous flat surface moving in a parallel free stream of an electrically conducting non-Newtonian viscoelastic fluid. The flow is subjected to a transverse uniform magnetic field. The constitutive equation of the fluid is modeled by that for a second grade fluid. Numerical results are obtained for the distribution of velocity and temperature profiles. The effects of various physical parameters like viscoelastic parameter, magnetic parameter and Prandtl number on various momentum and heat transfer characteristics are discussed in detail and shown graphically.

  8. Existence of bounded uniformly continuous mild solutions on $\\Bbb{R}$ of evolution equations and some applications

    CERN Document Server

    Basit, Bolis

    2011-01-01

    We prove that there is $x_{\\phi}\\in X$ for which (*)$\\frac{d u(t)}{dt}= A u(t) + \\phi (t) $, $u(0)=x$ has on $\\r$ a mild solution $u\\in C_{ub} (\\r,X)$ (that is bounded and uniformly continuous) with $u(0)=x_{\\phi}$, where $A$ is the generator of a holomorphic $C_0$-semigroup $(T(t))_{t\\ge 0}$ on ${X}$ with sup $_{t\\ge 0} \\,||T(t)|| 0$, then $u\\in \

  9. The use of intensity-modulated radiation therapy photon beams for improving the dose uniformity of electron beams shaped with MLC

    International Nuclear Information System (INIS)

    Electrons are ideal for treating shallow tumors and sparing adjacent normal tissue. Conventionally, electron beams are collimated by cut-outs that are time-consuming to make and difficult to adapt to tumor shape throughout the course of treatment. We propose that electron cut-outs can be replaced using photon multileaf collimator (MLC). Two major problems of this approach are that the scattering of electrons causes penumbra widening because of a large air gap, and available commercial treatment planning systems (TPSs) do not support MLC-collimated electron beams. In this study, these difficulties were overcome by (1) modeling electron beams collimated by photon MLC for a commercial TPS, and (2) developing a technique to reduce electron beam penumbra by adding low-energy intensity-modulated radiation therapy (IMRT) photons (4 MV). We used blocks to simulate MLC shielding in the TPS. Inverse planning was used to optimize boost photon beams. This technique was applied to a parotid and a central nervous system (CNS) clinical case. Combined photon and electron plans were compared with conventional plans and verified using ion chamber, film, and a 2D diode array. Our studies showed that the beam penumbra for mixed beams with 90 cm source to surface distance (SSD) is comparable with electron applicators and cut-outs at 100 cm SSD. Our mixed-beam technique yielded more uniform dose to the planning target volume and lower doses to various organs at risk for both parotid and CNS clinical cases. The plans were verified with measurements, with more than 95% points passing the gamma criteria of 5% in dose difference and 5 mm for distance to agreement. In conclusion, the study has demonstrated the feasibility and potential advantage of using photon MLC to collimate electron beams with boost photon IMRT fields.

  10. Absence of internal tidal beams due to non-uniform stratification

    NARCIS (Netherlands)

    Gerkema, T.; van Haren, H.

    2012-01-01

    A linear internal-tide generation model is applied to the Faeroe–Shetland Channel, using observed profiles of stratification. Several degrees of simplification are considered: 1) uniform, i.e. constant N; 2) vertically varying N (z); 3) the full N(x, z) and associated geostrophic background flows. I

  11. High-frequency beam matching at the input of an ion linac with uniform spatial quadrupole focusing

    International Nuclear Information System (INIS)

    .There is offered a mathing device at the input of an accelerator with quadrupole spatial-uniform hiqh-frequency focusing, which removes phase dependence of the accelerator acceptance and essentially reduces the growth of the beam emittance in the acceleration process. The mathing theory is given and mathing conditions are formulated. Working ability of the smooth envelope method for the initial part of the accelerator and its applicability for investigating the coordination problems is shown. Comparison of the obtained data shows, that the effective acceptance increases approximately twice during the use of the coordinating device. For most of the input phases the acceptance becomes practically phase-independent

  12. Numerical study of chaotic oscillations in the electron beam with virtual cathode in the external non-uniform magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Hramov, Alexander E., E-mail: aeh@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation); Koronovskii, Alexey A., E-mail: alkor@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation); Kurkin, Semen, E-mail: KurkinSA@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation)

    2010-07-05

    In this Letter the results of theoretical investigations of the chaotic microwave oscillator based on the electron beam with a virtual cathode are presented. Nonlinear non-stationary processes in these electron systems are studied by means of numerical analysis of 2.5D model. It was discovered that the non-uniform external magnetic field value controls the dynamical regime of oscillations in the virtual cathode oscillator. The processes of the chaotization of output microwave radiation are described and interpreted from the point of view of the formation and interaction of electron structures (bunches) in the electron beams. The numerical results have shown that the investigated electron system with virtual cathode could be considered as a promising controlled source of wideband chaotic oscillations in the microwave range.

  13. Experimental and analytical investigation of reinforced high strength concrete continuous beams strengthened with fiber reinforced polymer

    International Nuclear Information System (INIS)

    Carbon and glass fiber reinforced polymer (CFRP and GFRP) are two materials suitable for strengthening the reinforced concrete (RC) beams. Although many in situ RC beams are of continuous constructions, there has been very limited research on the behavior of such beams with externally applied FRP laminate. In addition, most design guidelines were developed for simply supported beams with external FRP laminates. This paper presents an experimental program conducted to study the flexural behavior and redistribution in moment of reinforced high strength concrete (RHSC) continuous beams strengthened with CFRP and GFRP sheets. Test results showed that with increasing the number of CFRP sheet layers, the ultimate strength increases, while the ductility, moment redistribution, and ultimate strain of CFRP sheet decrease. Also, by using the GFRP sheet in strengthening the continuous beam reduced loss in ductility and moment redistribution but it did not significantly increase ultimate strength of beam. The moment enhancement ratio of the strengthened continuous beams was significantly higher than the ultimate load enhancement ratio in the same beam. An analytical model for moment-curvature and load capacity are developed and used for the tested continuous beams in current and other similar studies. The stress-strain curves of concrete, steel and FRP were considered as integrity model. Stress-strain model of concrete is extended from Oztekin et al.'s model by modifying the ultimate strain. Also, new parameters of equivalent stress block are obtained for flexural calculation of RHSC beams. Good agreement between experiment and prediction values is achieved.

  14. CEBAF [Continuous Electron Beam Accelerator Facility] design overview and project status

    International Nuclear Information System (INIS)

    This paper discusses the design and specifications of the Continuous Electron Beam Accelerator Facility. Beam performance objectives are discussed, as well as the recirculating linac concept, the injector, cavities, cryogenic system, beam transport and optics, rf system and construction progress. 19 refs., 10 figs

  15. Static and dynamic stability of uniform shear beam-columns under generalized boundary conditions

    Science.gov (United States)

    Dario Aristizabal-Ochoa, J.

    2007-10-01

    The stability and dynamic analyses (i.e., the buckling loads, natural frequencies and the corresponding modes of buckling and vibration) of a 2D shear beam-column with generalized boundary conditions (i.e., with rotational restraints and lateral bracings as well as lumped masses at both ends) and subjected to linearly distributed axial load along its span are presented in a classic manner. The two governing equations of dynamic equilibrium, that is, the classical shear-wave equation and the bending moment equation are sufficient to determine the modes of vibration and buckling, and the corresponding natural frequencies and buckling loads, respectively. The proposed model includes the simultaneous effects of shear deformations, translational and rotational inertias of all masses considered, the linearly applied axial load along the span, and the end restraints (rotational and lateral bracings at both ends). These effects are particularly important in members with limited end rotational restraints and lateral bracings. Analytical results indicate that except for members with perfectly clamped ends, the stability and dynamic behavior of shear beams and shear beam columns are governed by the bending moment equation, rather than the second-order differential equation of transverse equilibrium (or shear-wave equation). This equation is formulated in the technical literature by simple applying transverse equilibrium at both ends of the member "ignoring" the bending moment equilibrium equation. This causes erroneous results in the stability and dynamic analyses of such members with supports that are not perfectly clamped. The proposed equations reproduce as special cases: (1) the non-classical vibration modes of shear beam-columns including the inversion of modes of vibration (i.e. higher modes crossing lower modes) in members with soft end conditions, and the phenomena of double frequencies at certain values of beam slenderness ( L/ r) and (2) the phenomena of tension

  16. Uniform longitudinal beam profiles in the Fermilab Recycler using adaptive rf correction

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Martin; Broemmelsiek, Daniel Robert; Chase, Brian; Crisp, James L.; Eddy, Nathan; Joireman, Paul W.; Ng, King Yuen; /Fermilab

    2007-06-01

    The Fermilab Recycler Ring is a permanent magnet based 8 GeV anti-proton storage ring. A wideband RF system, driven with ARB's (ARBitrary waveform generators), allows the system to produce programmable barrier waveforms. Beam current profile distortion was observed, its origin verified both experimentally and theoretically, and an FPGA-based correction system was designed, tested and implemented to level the bunch profile.

  17. Continuous guided beams of slow and internally cold polar molecules

    International Nuclear Information System (INIS)

    In the last years we have developed a source which produces high-flux beams of electrically guided cold molecules. A molecular gas is cooled by collisions with a cryogenic buffer gas, after which an electric quadrupole guide selects slow molecules in low-field-seeking states and transports them out of the cryogenic environment. For formaldehyde we have demonstrated the high state-purity in the extracted beam by a laser-depletion experiment. As an alternative to the laser-depletion technique, we have qualitatively confirmed internal cooling for other species as well, from time-of-flight measurements obtained at different buffer-gas settings. Here, we review the source, including its technical aspects and optimization, and present its versatility from results obtained with different molecules.

  18. Beam characterization of a new continuous wave radio frequency quadrupole accelerator

    International Nuclear Information System (INIS)

    A new Continuous Wave (CW) Radio Frequency Quadrupole (RFQ) for the ATLAS (Argonne Tandem Linac Accelerator System) Intensity Upgrade was developed, built and tested at Argonne National Laboratory. We present here a characterization of the RFQ output beam in the longitudinal phase space, as well as a measurement of the transverse beam halo. Measurement results are compared to simulations performed using the beam dynamics code TRACK. -- Highlights: • Beam commissioning of a new CW RFQ has been performed at Argonne National Laboratory. • Energy spread and bunch shape measurements were conducted. • The formation of a beam halo in the transverse phase space was studied

  19. Three-dimensional vibration analysis of a uniform beam with offset inertial masses at the ends

    Science.gov (United States)

    Robertson, D. K.

    1985-01-01

    Analysis of a flexible beam with displaced end-located inertial masses is presented. The resulting three-dimensional mode shape is shown to consist of two one-plane bending modes and one torsional mode. These three components of the mode shapes are shown to be linear combinations of trigonometric and hyperbolic sine and cosine functions. Boundary conditions are derived to obtain nonlinear algebraic equations through kinematic coupling of the general solutions of the three governing partial differential equations. A method of solution which takes these boundary conditions into account is also presented. A computer program has been written to obtain unique solutions to the resulting nonlinear algebraic equations. This program, which calculates natural frequencies and three-dimensional mode shapes for any number of modes, is presented and discussed.

  20. DEFLECTION OF A HETEROGENEOUS WIDE-BEAM UNDER UNIFORM PRESSURE LOAD

    Energy Technology Data Exchange (ETDEWEB)

    T. V. Holschuh; T. K. Howard; W. R. Marcum

    2014-07-01

    Oregon State University (OSU) and the Idaho National Laboratory (INL) are currently collaborating on a test program which entails hydro-mechanical testing of a generic plate type fuel element, or generic test plate assembly (GTPA), for the purpose of qualitatively demonstrating mechanical integrity of uranium-molybdenum monolithic plates as compared to that of uranium aluminum dispersion, and aluminum fuel plates onset by hydraulic forces. This test program supports ongoing work conducted for/by the Global Threat Reduction Initiative (GTRI) Fuels Development Program. This study’s focus supports the ongoing collaborative effort by detailing the derivation of an analytic solution for deflection of a heterogeneous plate under a uniform, distributed load in order to predict the deflection of test plates in the GTPA. The resulting analytical solutions for three specific boundary condition sets are then presented against several test cases of a homogeneous plate. In all test cases considered, the results for both homogeneous and heterogeneous plates are numerically identical to one another, demonstrating correct derivation of the heterogeneous solution. Two additional problems are presents herein that provide a representative deflection profile for the plates under consideration within the GTPA. Furthermore, qualitative observations are made about the influence of a more-rigid internal fuel-meat region and its influence on the overall deflection profile of a plate. Present work is being directed to experimentally confirm the analytical solution’s results using select materials.

  1. Beam test studies of 3D pixel sensors irradiated non-uniformly for the ATLAS forward physics detector

    International Nuclear Information System (INIS)

    Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness, since the electrode distance is decoupled from the bulk thickness. In recent years significant progress has been made in the development of 3D sensors, which culminated in the sensor production for the ATLAS Insertable B-Layer (IBL) upgrade carried out at CNM (Barcelona, Spain) and FBK (Trento, Italy). Based on this success, the ATLAS Forward Physics (AFP) experiment has selected the 3D pixel sensor technology for the tracking detector. The AFP project presents a new challenge due to the need for a reduced dead area with respect to IBL, and the in-homogeneous nature of the radiation dose distribution in the sensor. Electrical characterization of the first AFP prototypes and beam test studies of 3D pixel devices irradiated non-uniformly are presented in this paper

  2. Beam test studies of 3D pixel sensors irradiated non-uniformly for the ATLAS forward physics detector

    Energy Technology Data Exchange (ETDEWEB)

    Grinstein, S., E-mail: sgrinstein@ifae.es [ICREA and Institut de Física d' Altes Energies (IFAE), Barcelona (Spain); Baselga, M. [Centro Nacional de Microelectronica, CNM-IMB (CSIC), Barcelona (Spain); Boscardin, M. [Fondazione Bruno Kessler, FBK-CMM, Trento (Italy); Christophersen, M. [U.S. Naval Research Laboratory, Washington (United States); Da Via, C. [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom); Dalla Betta, G.-F. [Universita degli Studi di Trento and INFN, Trento (Italy); Darbo, G. [INFN Sezione di Genova, Genova (Italy); Fadeyev, V. [Santa Cruz Institute for Particle Physics, University of California, Santa Cruz (United States); Fleta, C. [Centro Nacional de Microelectronica, CNM-IMB (CSIC), Barcelona (Spain); Gemme, C. [Universita degli Studi di Trento and INFN, Trento (Italy); Grenier, P. [SLAC National Accelerator Laboratory, Menlo Park (United States); Jimenez, A.; Lopez, I.; Micelli, A. [ICREA and Institut de Física d' Altes Energies (IFAE), Barcelona (Spain); Nelist, C. [INFN Sezione di Genova, Genova (Italy); Parker, S. [University of Hawaii, c/o Lawrence Berkeley Laboratory, Berkeley (United States); Pellegrini, G. [Centro Nacional de Microelectronica, CNM-IMB (CSIC), Barcelona (Spain); Phlips, B. [U.S. Naval Research Laboratory, Washington (United States); Pohl, D.-L. [University of Bonn, Bonn (Germany); Sadrozinski, H.F.-W. [Santa Cruz Institute for Particle Physics, University of California, Santa Cruz (United States); and others

    2013-12-01

    Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness, since the electrode distance is decoupled from the bulk thickness. In recent years significant progress has been made in the development of 3D sensors, which culminated in the sensor production for the ATLAS Insertable B-Layer (IBL) upgrade carried out at CNM (Barcelona, Spain) and FBK (Trento, Italy). Based on this success, the ATLAS Forward Physics (AFP) experiment has selected the 3D pixel sensor technology for the tracking detector. The AFP project presents a new challenge due to the need for a reduced dead area with respect to IBL, and the in-homogeneous nature of the radiation dose distribution in the sensor. Electrical characterization of the first AFP prototypes and beam test studies of 3D pixel devices irradiated non-uniformly are presented in this paper.

  3. Beam Test Studies of 3D Pixel Sensors Irradiated Non-Uniformly for the ATLAS Forward Physics Detector

    CERN Document Server

    Grinstein, S; Boscardin, M; Christophersen, M; Da Via, C; Betta, G -F Dalla; Darbo, G; Fadeyev, V; Fleta, C; Gemme, C; Grenier, P; Jimenez, A; Lopez, I; Micelli, A; Nelist, C; Parker, S; Pellegrini, G; Phlips, B; Pohl, D L; Sadrozinski, H F -W; Sicho, P; Tsiskaridze, S

    2013-01-01

    Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness, since the electrode distance is decoupled from the bulk thickness. In recent years significant progress has been made in the development of 3D sensors, which culminated in the sensor production for the ATLAS Insertable B-Layer (IBL) upgrade carried out at CNM (Barcelona, Spain) and FBK (Trento, Italy). Based on this success, the ATLAS Forward Physics (AFP) experiment has selected the 3D pixel sensor technology for the tracking detector. The AFP project presents a new challenge due to the need for a reduced dead area with respect to IBL, and the in-homogeneous nature of the radiation dose distribution in the sensor. Electrical characterization of the first AFP prototypes and beam test studies of 3D pixel devices irradiated non-uniformly are presented in this paper.

  4. Beam Shaping of High-power Laser Diode Arrays by Continuous Surface-relief Elements

    OpenAIRE

    Ehbets, Peter; Herzig, Hans-Peter; Dändliker, René; Regnault, P.; Kjelberg, I.

    2007-01-01

    A breadboard for beam shaping of high-power laser diode arrays (LDAs) has been realized. The coherent beams are added with the aid of a continuous surface-relief fan-in element. It results in a nearly symmetric single lobed beam of collimated light with maximum conversion efficiency. The theoretical efficiency is determined to be 96•7%. Experimentally, one third of the total power is now in the central peak.

  5. Selective optical assembly of highly uniform nanoparticles by doughnut-shaped beams.

    Science.gov (United States)

    Ito, Syoji; Yamauchi, Hiroaki; Tamura, Mamoru; Hidaka, Shimpei; Hattori, Hironori; Hamada, Taichi; Nishida, Keisuke; Tokonami, Shiho; Itoh, Tamitake; Miyasaka, Hiroshi; Iida, Takuya

    2013-01-01

    A highly efficient natural light-harvesting antenna has a ring-like structure consisting of dye molecules whose absorption band changes through selective evolutionary processes driven by external stimuli, i.e., sunlight depending on its territory and thermal fluctuations. Inspired by this fact, here, we experimentally and theoretically demonstrate the selective assembling of ring-like arrangements of many silver nanorods with particular shapes and orientations onto a substrate by the light-induced force of doughnut beams with different colours (wavelengths) and polarizations in conjunction with thermal fluctuations at room temperature. Furthermore, the majority of nanorods are electromagnetically coupled to form a prominent red-shifted collective mode of localized surface plasmons resonant with the wavelength of the irradiated light, where a spectral broadening also appears for the efficient broadband optical response. The discovered principle is a promising route for "bio-inspired selective optical assembly" of various nanomaterials that can be used in the wide field of nanotechnology. PMID:24157739

  6. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    Science.gov (United States)

    Alferjani, M. B. S.; Samad, A. A. Abdul; Elrawaff, Blkasem S.; Elzaroug, Omer; Mohamad, Noridah

    2015-05-01

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

  7. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    International Nuclear Information System (INIS)

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results

  8. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    Energy Technology Data Exchange (ETDEWEB)

    Alferjani, M. B. S.; Samad, A. A. Abdul; Mohamad, Noridah [Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat (Malaysia); Elrawaff, Blkasem S.; Elzaroug, Omer [Faculty of Civil Engineering Omar Al Mukhtar University, Bayda, Libya, Africa (Libya)

    2015-05-15

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

  9. Subsurface plasma in beam of continuous CO2-laser

    Science.gov (United States)

    Danytsikov, Y. V.; Dymshakov, V. A.; Lebedev, F. V.; Pismennyy, V. D.; Ryazanov, A. V.

    1986-03-01

    Experiments performed at the Institute of Atomic Energy established the conditions for formation of subsurface plasma in substances by laser radiation and its characteristics. A quasi-continuous CO2 laser emitting square pulses of 0.1 to 1.0 ms duration and 1 to 10 kW power as well as a continuous CO2 laser served as radiation sources. Radiation was focused on spots 0.1 to 0.5 mm in diameter and maintained at levels ensuring constant power density during the interaction time, while the temperature of the target surface was measured continuously. Metals, graphite and dielectric materials were tested with laser action taking place in air N2 + O2 mixtures, Ar or He atmosphere under pressures of 0.01 to 1.0 atm. Data on radiation intensity thresholds for evaporation and plasma formation were obtained. On the basis of these thresholds, combined with data on energy balance and the temperature profile in plasma layers, a universal state diagram was constructed for subsurface plasma with nonquantified surface temperature and radiation intensity coordinates.

  10. Existence of bounded uniformly continuous mild solutions on $\\Bbb{R}$ of evolution equations and their asymptotic behaviour

    CERN Document Server

    Basit, Bolis

    2011-01-01

    We prove that $u'= A u + \\phi $ has on $\\Bbb{R}$ a mild solution $u_{\\phi}\\in BUC (\\Bbb{R},X)$ (that is bounded and uniformly continuous), where $A$ is the generator of a $C_0$-semigroup on the Banach space ${X}$ with resolvent satisfying $||R(it,A)||= O(|t|^{-\\theta})$, $|t|\\to \\infty $, with some $\\theta > 1/2$, $\\phi\\in L^{\\infty} (\\Bbb{R},{X})$ and $i\\,sp (\\phi)\\cap \\sigma (A)=\\emptyset$. As a consequence it is shown that if ${\\Cal F}$ is the space of almost periodic, almost automorphic, bounded Levitan almost periodic or certain classes of recurrent functions and $\\phi$ as above is such that $M_h \\phi:=(1/h)\\int_0^h \\phi (\\cdot+s)\\, ds \\in \\Cal {F}$ for each $h >0$, then $u_{\\phi}\\in \\Cal {F}\\cap BUC (\\Bbb{R},X)$. These results seem new and strengthen several recent theorems.

  11. Multipass beam breakup in the CEBAF [Continuous Electron Beam Accelerator Facility] superconducting linac

    International Nuclear Information System (INIS)

    Multipass beam breakup can severely limit current in superconducting linear accelerators due to the inherently high Q's of transverse deflecting modes of the rf cavities. The success of higher-order-mode damping in increasing threshold currents for the 4-pass CEBAF SRF linac design is investigated with computer modeling. This simulation is shown to be in agreement with theoretical analyses which have successfully described beam breakup in the Stanford superconducting, recirculating linac. Numerical evaluation of an analytic treatment by Gluckstern of multipass beam breakup with distributed cavities is also found to be consistent with the computer model. Application of the simulation to the design array of 400 five-cell CEBAF/Cornell cavities with measured higher-order-mode damping indicates that the beam breakup threshold current is at least an order of magnitude above the CEBAF design current of 200 μA

  12. Structural Behavior of Continuous Prestressed Steel Fiber Reinforced High Strength Concrete Beam

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The flexural behaviors of continuous fully and partially prestressed steel fiber reinforced high strength concrete beams are studied by experiment and nonlinear finite element analysis. Three levels of partial prestress ratio (PPR) are considered, and three pairs of two-span continuous beams with box sections varying in size are designed. The major parameters involved in the study include the PPR and the fiber location. It is concluded that the prestressed high strength concrete beam exhibits satisfactory ductility; the influences of steel fiber on the crack behaviors for partially prestressed beams are not as obvious as those for fully prestressed ones; steel fibers can improve the structural stiffness after cracking for fully prestressed high strength concrete beams; the moment redistribution from mid-span to intermediate support in the first stage should be mainly considered in practical design.

  13. A new approach for elasto-plastic finite strain analysis of cantilever beams subjected to uniform bending moment

    Indian Academy of Sciences (India)

    GOKHAN T TAYYAR

    2016-04-01

    The reliability and limits of solutions for static structural analysis depend on the accuracy of the curvature and deflection calculations. Even if the material model is close to the actual material behavior, physically unrealistic deflections or divergence problems are unavoidable in the analysis if an appropriate fundamental kinematic theory is not chosen. Moreover, accurate deflection calculation plays an important role in ultimate strength analysis where in-plane stresses are considered. Therefore, a more powerful method is neededto achieve reliable deflection calculation and modeling. For this purpose, a new advanced step was developed by coupling the elasto-plastic material behavior with precise general planar kinematic analysis. The deflection is generated precisely without making geometric assumptions or using differential equations of the deflection curve. An analytical finite strain solution was derived for an elasto-plastic prismatic/non-prismatic rectangular cross-sectioned beam under a uniform moment distribution. A comparison of the analytical results with thosefrom the Abaqus FEM software package reveals a coherent correlation.

  14. Concept of Powerful Multistage Coaxial Cyclotron for Pulsed and Continuous Beam Production

    CERN Document Server

    Tumanyan, A R; Guiragossian, Z G T; Akopov, N Z

    1999-01-01

    The concept of large-radius multistage coaxial cyclotrons having separated orbits is described, to generate proton beams of 120-2000 MeV energy at tens of GW pulsed and hundreds of MW in continuous beam power operation. Accelerated beam losses must be less than 0.1 W/m for the intercepted average beam power linear density. The concept is inherently configured to actively compensate the longitudinal and transverse space charge expansion in beam bunches. These are based on (1) actively varying the bunch acceleration equilibrium phase while maintaining isochronism, independently for each cyclotron turns; (2) independently changing the acceleration voltage for each turn together with orbit corrections that preserve isochronism; (3) independently changing the transverse betatron oscillation tune shift, to assure non-resonant operation. Also, (4) sextupole lenses are included to compensate for chromaticity effects. Moreover, the concept is based on optimum uses of practical successful results so far achieved in bea...

  15. Propagation characteristics of Bessel beams generated by continuous, incoherent light sources.

    Science.gov (United States)

    Altıngöz, Ceren; Yalızay, Berna; Akturk, Selcuk

    2015-08-01

    We investigate the propagation behavior of Bessel beams generated by incoherent, continuous light sources. We perform experiments with narrowband and broadband light emitting diodes, and, for comparison, with a laser diode. We observe that the formation of Bessel beams is affected minimally by temporal coherence, while spatial coherence determines the longitudinal evolution of the beam profile. With spatially incoherent beams, the fringe contrast is comparable to the coherent case at the beginning of the Bessel zone, while it completely fades away by propagation, turning into a cylindrical light pipe. Our results show that beam shaping methods can be extended to cases of limited spatial coherence, paving the way for potential new uses and applications of such sources. PMID:26367302

  16. Experimental study on ferritic stainless steel simply supported and continuous beams

    OpenAIRE

    Arrayago Luquin, Itsaso; Real Saladrigas, Esther

    2015-01-01

    Development of efficient design guidance for stainless steel structures is key for the increased use of this corrosion-resistant material by considering both nonlinear behaviour and strain hardening into resistance prediction expressions, together with the moment redistribution in indeterminate structures. With the aim of analysing the bending moment redistribution capacity of ferritic stainless steel beams, a comprehensive experimental programme on continuous beams is presented. These tests ...

  17. Surface modification of the metal plates using continuous electron beam process (CEBP)

    International Nuclear Information System (INIS)

    Highlights: • We performed surface modification of SM20C, SUS303, and Al6061 using CEBP. • We analyzed surface properties and microstructure after electron-beam irradiation. • The surface quality was improved after electron-beam irradiation. • The surface hardness for SM20C was increased by ∼50% after CEBP irradiation. - Abstract: The finishing process is an important component of the quality-control procedure for final products in manufacturing applications. In this study, we evaluated the performance of continuous electron-beam process as the final process for finishing SM20C (steel alloy), SUS303 (stainless steel alloy), and Al6061 (aluminum alloy) surfaces both on the initially smooth and rough surfaces. Surface modification of the metals was carried out by varying the feed and frequency of the continuous electron-beam irradiation procedure. The resulting surface roughness was examined with respect to the initial surface roughness of the metals. SM20C and SUS303 experienced an improvement in surface roughness, particularly for initially rough surfaces. Continuous electron-beam process produced craters during the process and the effect of this phenomenon on the resulting surface roughness was relatively large with the initially smooth SM20C and SUS303 alloy surfaces. For Al6061, the continuous electron-beam process was effective at improving its surface roughness even with the initially smooth surface under the optimized conditions of process; this was attributed to its low melting point. Scanning electron microscopy was used to identify metallurgical variation within the thin melted and re-solidification layers of the tested alloys. Changes in the surface contact angle and hardness before and after electron-beam irradiation were also examined

  18. Thermo-mechanical simulation and parameters optimization for beam blank continuous casting

    International Nuclear Information System (INIS)

    The objective of this work is to optimize the process parameters of beam blank continuous casting in order to ensure high quality and productivity. A transient thermo-mechanical finite element model is developed to compute the temperature and stress profile in beam blank continuous casting. By comparing the calculated data with the metallurgical constraints, the key factors causing defects of beam blank can be found out. Then based on the subproblem approximation method, an optimization program is developed to search out the optimum cooling parameters. Those optimum parameters can make it possible to run the caster at its maximum productivity, minimum cost and to reduce the defects. Now, online verifying of this optimization project has been put in practice, which can prove that it is very useful to control the actual production

  19. Holography of human pathologic specimens with continuous-beam lasers through plastination

    Science.gov (United States)

    Myers, M. Bert; Bickley, Harmon

    1991-07-01

    Since evaporation of cellular water leads to shrinkage and motion, holography of human tissue specimens is generally possible only with pulsed lasers. Plastination is a preservation technique in which cellular water is removed and replaced with a curable polymer. This preserves the tissue, including even the cellular anatomy, and renders the specimen rigid enough for holography with continuous beam lasers.

  20. Study of performance of electronic dosemeters in continuous and pulsed X-radiation beams

    International Nuclear Information System (INIS)

    Personal radiation monitoring is a basic procedure to verify the compliance to regulatory requirements for radiological protection. Electronic personal dosimeters (EPD) based on solid state detectors have largely been used for personnel monitoring; including for pulsed radiation beams where their responses are not well known and deficiencies have been reported. In this work, irradiation conditions for testing the response of EPDs in both continuous and pulsed X-ray beams were studied to be established in a constant potential Seifert-Pantak and in a medical Pulsar 800 Plus VMI X-ray machines. Characterization of X-ray beams was done in terms of tube voltage, half-value layer, mean energy and air kerma rate. A Xi R/F Unfors solid state dosimeter used as reference for air kerma measurements was verified against a RC-6 and 10X6-6 Radical ionization chambers as far its metrological coherence. Rad-60 RADOS, PDM- 11 Aloka and EPD MK2 Thermo electron EPDs were selected to be tested in terms of relative intrinsic error and energy response in similar to IEC RQR, IEC RQA and ISO N reference radiations. Results demonstrated the reliability of the solid state Xi R/F Unfors dosimeter to be as reference dosimeter although its response was affected by heavily filtered beams. Results also showed that relative intrinsic errors in the response of the EPDs in terms of personal dose equivalent, Hp(10), were higher than the requirement established for continuous beams. In pulsed beams, some EPDs showed inadequate response and high relative intrinsic errors. This work stressed the need of performing additional checks for EPDs, besides the limited 137Cs beam calibration, before using them in pulsed X-ray beams. (author)

  1. SU-E-T-586: Field Size Dependence of Output Factor for Uniform Scanning Proton Beams: A Comparison of TPS Calculation, Measurement and Monte Carlo Simulation

    International Nuclear Information System (INIS)

    Purpose: Output dependence on field size for uniform scanning beams, and the accuracy of treatment planning system (TPS) calculation are not well studied. The purpose of this work is to investigate the dependence of output on field size for uniform scanning beams and compare it among TPS calculation, measurements and Monte Carlo simulations. Methods: Field size dependence was studied using various field sizes between 2.5 cm diameter to 10 cm diameter. The field size factor was studied for a number of proton range and modulation combinations based on output at the center of spread out Bragg peak normalized to a 10 cm diameter field. Three methods were used and compared in this study: 1) TPS calculation, 2) ionization chamber measurement, and 3) Monte Carlos simulation. The XiO TPS (Electa, St. Louis) was used to calculate the output factor using a pencil beam algorithm; a pinpoint ionization chamber was used for measurements; and the Fluka code was used for Monte Carlo simulations. Results: The field size factor varied with proton beam parameters, such as range, modulation, and calibration depth, and could decrease over 10% from a 10 cm to 3 cm diameter field for a large range proton beam. The XiO TPS predicted the field size factor relatively well at large field size, but could differ from measurements by 5% or more for small field and large range beams. Monte Carlo simulations predicted the field size factor within 1.5% of measurements. Conclusion: Output factor can vary largely with field size, and needs to be accounted for accurate proton beam delivery. This is especially important for small field beams such as in stereotactic proton therapy, where the field size dependence is large and TPS calculation is inaccurate. Measurements or Monte Carlo simulations are recommended for output determination for such cases

  2. A continuous wave fan beam tomography system having a best estimating filter

    International Nuclear Information System (INIS)

    A continuous wave fan beam tomographic system is described which continuously samples X-ray absorption values and a means of providing a best-estimate of the X-ray absorption values at discrete points in time determined by sampling signal s(t). The means to provide the best-estimate include a continuous filter having a frequency range defined by the geometry of the mechanical system. Errors due to the statistical variation in photon emissions of the X-ray source are thereby minimized and the effective signal-to-noise ratio of signals is enhanced, which in turn allows a significant reduction in radiation dosage. (author)

  3. Exact analytical solutions of continuity equation for electron beams precipitating in Coulomb collisions

    Energy Technology Data Exchange (ETDEWEB)

    Dobranskis, R. R.; Zharkova, V. V., E-mail: valentina.zharkova@northumbria.ac.uk [Department of Mathematics and Information Sciences, University of Northumbria, Newcastle upon Tyne NE1 2XP (United Kingdom)

    2014-06-10

    The original continuity equation (CE) used for the interpretation of the power law energy spectra of beam electrons in flares was written and solved for an electron beam flux while ignoring an additional free term with an electron density. In order to remedy this omission, the original CE for electron flux, considering beam's energy losses in Coulomb collisions, was first differentiated by the two independent variables: depth and energy leading to partial differential equation for an electron beam density instead of flux with the additional free term. The analytical solution of this partial differential continuity equation (PDCE) is obtained by using the method of characteristics. This solution is further used to derive analytical expressions for mean electron spectra for Coulomb collisions and to carry out numeric calculations of hard X-ray (HXR) photon spectra for beams with different parameters. The solutions revealed a significant departure of electron densities at lower energies from the original results derived from the CE for the flux obtained for Coulomb collisions. This departure is caused by the additional exponential term that appeared in the updated solutions for electron differential density leading to its faster decrease at lower energies (below 100 keV) with every precipitation depth similar to the results obtained with numerical Fokker-Planck solutions. The effects of these updated solutions for electron densities on mean electron spectra and HXR photon spectra are also discussed.

  4. Analytical modeling of large amplitude free vibration of non-uniform beams carrying a both transversely and axially eccentric tip mass

    Science.gov (United States)

    Malaeke, Hasan; Moeenfard, Hamid

    2016-03-01

    The objective of this paper is to study large amplitude flexural-extensional free vibration of non-uniform cantilever beams carrying a both transversely and axially eccentric tip mass. The effects of variable axial force is also taken into account. Hamilton's principle is utilized to obtain the partial differential equations governing the nonlinear vibration of the system as well as the corresponding boundary conditions. A numerical finite difference scheme is proposed to find the natural frequencies and mode shapes of the system which is validated specifically for a beam with linearly varying cross section. Using a single mode approximation in conjunction with the Lagrange method, the governing equations are reduced to a set of two nonlinear ordinary differential equations in terms of end displacement components of the beam which are coupled due to the presence of the transverse eccentricity. These temporal coupled equations are then solved analytically using the multiple time scales perturbation technique. The obtained analytical results are compared with the numerical ones and excellent agreement is observed. The qualitative and quantitative knowledge resulting from this research is expected to enable the study of the effects of eccentric tip mass and non-uniformity on the large amplitude flexural-extensional vibration of beams for improved dynamic performance.

  5. Langmuir turbulence and quasilinear interactions of a hot electron beam in the inhomogeneous solar corona plasma with a uniform electric field

    International Nuclear Information System (INIS)

    Using numerical simulation of the quasilinear equations, the propagation of an electron beam through inhomogeneous solar corona plasma and generation of Langmuir waves are investigated by taking into account a uniform electric field. The level of the excited Langmuir waves is remarkably enhanced by decreasing density and the applied electric field. The mean velocity of propagation of the beam is not a constant and decreases with distance from the injection point. The effect of the electric field is more pronounced on the slow electrons and accelerates them to high velocity region while the density gradient mainly affects the fast electrons and effectively decelerates them. -- Highlights: ► We simulate a beam–plasma system in an inhomogeneous plasma with an electric field. ► In this model of plasma the levels of Langmuir waves are enhanced very quickly. ► The average velocity of beam is no longer constant during the course of propagation.

  6. Langmuir turbulence and quasilinear interactions of a hot electron beam in the inhomogeneous solar corona plasma with a uniform electric field

    Energy Technology Data Exchange (ETDEWEB)

    Khalilpour, H., E-mail: h_khalilpour@pnu.ac.ir [Physics Department, Payame Noor University, 19395-4697, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Foroutan, G. [Physics Department, Faculty of Science, Sahand University of Technology, 51335-1996, Tabriz, Islamic Republic of Iran (Iran, Islamic Republic of)

    2012-01-30

    Using numerical simulation of the quasilinear equations, the propagation of an electron beam through inhomogeneous solar corona plasma and generation of Langmuir waves are investigated by taking into account a uniform electric field. The level of the excited Langmuir waves is remarkably enhanced by decreasing density and the applied electric field. The mean velocity of propagation of the beam is not a constant and decreases with distance from the injection point. The effect of the electric field is more pronounced on the slow electrons and accelerates them to high velocity region while the density gradient mainly affects the fast electrons and effectively decelerates them. -- Highlights: ► We simulate a beam–plasma system in an inhomogeneous plasma with an electric field. ► In this model of plasma the levels of Langmuir waves are enhanced very quickly. ► The average velocity of beam is no longer constant during the course of propagation.

  7. Improvements of PKU PMECRIS for continuous hundred hours CW proton beam operation

    International Nuclear Information System (INIS)

    In order to improve the source stability, a long term continuous wave (CW) proton beam experiment has been carried out with Peking University compact permanent magnet 2.45 GHz ECR ion source (PKU PMECRIS). Before such an experiment a lot of improvements and modifications were completed on the source body, the Faraday cup and the PKU ion source test bench. At the beginning of 2015, a continuous operation of PKU PMECRIS for 306 h with more than 50 mA CW beam was carried out after success of many short term tests. No plasma generator failure or high voltage breakdown was observed during that running period and the proton source reliability is near 100%. Total beam availability, which is defined as 35-keV beam-on time divided by elapsed time, was higher than 99% [S. X. Peng et al., Chin. Phys. B 24(7), 075203 (2015)]. A re-inspection was performed after another additional 100 h operation (counting time) and no obvious sign of component failure was observed. Counting the previous source testing time together, this PMECRs longevity is now demonstrated to be greater than 460 h. This paper is mainly concentrated on the improvements for this long term experiment

  8. Improvements of PKU PMECRIS for continuous hundred hours CW proton beam operation

    Science.gov (United States)

    Peng, S. X.; Zhang, A. L.; Ren, H. T.; Zhang, T.; Zhang, J. F.; Xu, Y.; Guo, Z. Y.; Chen, J. E.

    2016-02-01

    In order to improve the source stability, a long term continuous wave (CW) proton beam experiment has been carried out with Peking University compact permanent magnet 2.45 GHz ECR ion source (PKU PMECRIS). Before such an experiment a lot of improvements and modifications were completed on the source body, the Faraday cup and the PKU ion source test bench. At the beginning of 2015, a continuous operation of PKU PMECRIS for 306 h with more than 50 mA CW beam was carried out after success of many short term tests. No plasma generator failure or high voltage breakdown was observed during that running period and the proton source reliability is near 100%. Total beam availability, which is defined as 35-keV beam-on time divided by elapsed time, was higher than 99% [S. X. Peng et al., Chin. Phys. B 24(7), 075203 (2015)]. A re-inspection was performed after another additional 100 h operation (counting time) and no obvious sign of component failure was observed. Counting the previous source testing time together, this PMECRs longevity is now demonstrated to be greater than 460 h. This paper is mainly concentrated on the improvements for this long term experiment.

  9. Improvements of PKU PMECRIS for continuous hundred hours CW proton beam operation

    Energy Technology Data Exchange (ETDEWEB)

    Peng, S. X., E-mail: sxpeng@pku.edu.cn; Ren, H. T.; Zhang, T.; Zhang, J. F.; Xu, Y.; Guo, Z. Y. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Zhang, A. L.; Chen, J. E. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2016-02-15

    In order to improve the source stability, a long term continuous wave (CW) proton beam experiment has been carried out with Peking University compact permanent magnet 2.45 GHz ECR ion source (PKU PMECRIS). Before such an experiment a lot of improvements and modifications were completed on the source body, the Faraday cup and the PKU ion source test bench. At the beginning of 2015, a continuous operation of PKU PMECRIS for 306 h with more than 50 mA CW beam was carried out after success of many short term tests. No plasma generator failure or high voltage breakdown was observed during that running period and the proton source reliability is near 100%. Total beam availability, which is defined as 35-keV beam-on time divided by elapsed time, was higher than 99% [S. X. Peng et al., Chin. Phys. B 24(7), 075203 (2015)]. A re-inspection was performed after another additional 100 h operation (counting time) and no obvious sign of component failure was observed. Counting the previous source testing time together, this PMECRs longevity is now demonstrated to be greater than 460 h. This paper is mainly concentrated on the improvements for this long term experiment.

  10. Design, fabrication, and beam commissioning of a continuous-wave four-rod rf quadrupole

    Science.gov (United States)

    Yin, X. J.; Yuan, Y. J.; Xia, J. W.; He, Y.; Zhao, H. W.; Zhang, X. H.; Du, H.; Li, Z. S.; Li, X. N.; Jiang, P. Y.; Yang, Y. Q.; Ma, L. Z.; Wu, J. X.; Xu, Z.; Sun, L. T.; Zhang, W.; Zhang, X. Z.; Meng, J.; Zhou, Z. Z.; Yao, Q. G.; Cai, G. Z.; Lu, W.; Wang, H. N.; Chen, W. J.; Zhang, Y.; Xu, X. W.; Xie, W. J.; Lu, Y. R.; Zhu, K.; Liu, G.; Yan, X. Q.; Gao, S. L.; Wang, Z.; Chen, J. E.

    2016-01-01

    A new heavy-ion linac within a continuous-wave (CW) 4-rod radio-frequency quadrupole (RFQ) was designed and constructed as the injector for the separated-sector cyclotron (SSC) at the Heavy Ion Research Facility at Lanzhou (HIRFL). In this paper, we present the development of and the beam commissioning results for the 53.667 MHz CW RFQ. In the beam dynamics design, the transverse phase advance at zero current, σ0 ⊥ , is maintained at a relatively high level compared with the longitudinal phase advance (σ0 ∥ ) to avoid parametric resonance. A quasi-equipartitioning design strategy was applied to control the emittance growth and beam loss. The installation error of the electrodes was checked using a FARO 3D measurement arm during the manufacturing procedure. This method represents a new approach to measuring the position shifts of electrodes in a laboratory environment and provides information regarding the manufacturing quality. The experimental results of rf measurements exhibited general agreement with the simulation results obtained using CST code. During on-line beam testing of the RFQ, two kinds of ion beams (40Ar 8 + and 16O5+ ) were transported and accelerated to 142.8 keV /u , respectively. These results demonstrate that the SSC-Linac has made a significant progress. And the design scheme and technology experiences developed in this work can be applied to other future CW RFQs.

  11. Modeling And Analysis of A Jeffcott Rotor As A Continuous Cantilever Beam And An Unbalanced Disk System

    OpenAIRE

    GUNDOGDU, Ömer; ALNEFAIE, Khaled; DIKEN, Hamza

    2014-01-01

    The paper presents simulations of a continuous cantilever beam and an unbalanced disk system by extending classical Jeffcott rotor approach to a model that gives the first three (or more) modes of the flexible beam. Normal modes of a constrained structure method are used to develop the equations of motion including gyroscopic effects. Centrifugal force created by the unbalanced mass of the disk is considered as a constraint for the flexible beam. The first three modes of the flexible beam hav...

  12. Quasi-continuous metasurface for ultra-broadband and polarization-controlled electromagnetic beam deflection

    OpenAIRE

    Yanqin Wang; Mingbo Pu; Zuojun Zhang; Xiong Li; Xiaoliang Ma; Zeyu Zhao; Xiangang Luo

    2015-01-01

    Two-dimensional metasurface has attracted growing interest in recent years, owing to its ability in manipulating the phase, amplitude and polarization state of electromagnetic wave within a single interface. However, most existing metasurfaces rely on the collective responses of a set of discrete meta-atoms to perform various functionalities. In this paper, we presented a quasi-continuous metasurface for high-efficiency and broadband beam steering in the microwave regime. It is demonstrated b...

  13. Neutron skyshine from end stations of the Continuous Electron Beam Accelerator Facility

    International Nuclear Information System (INIS)

    The MORSE CG code from Oak Ridge National Laboratory was applied to the estimation of the neutron skyshine from three end stations of the Continuous Electron Beam Accelerator Facility (CEBAF), Newport News, VA. Calculations with other methods and an experiment had been directed at assessing the annual neutron dose equivalent at the site boundary. A comparison of results obtained with different methods is given, and the effect of different temperatures and humidities will be discussed

  14. Mass flow prediction of the coriolis meter using C0 continuous beam elements

    Science.gov (United States)

    Binulal, B. R.; Rajan, Akash; Abhilash, Suryan R.; Kochupillai, Jayaraj; Kim, Heuy Dong

    2015-06-01

    A three node C0 continuous isoparametric beam element is formulated to model the curved pipe conveying fluid in three dimensional configuration. The equations of motion for the combined structure and fluid domain including added mass effect, Coriolis effect, centrifugal effect and the effect of pressure on the walls of pipe have been developed by Paidoussis. This equation is converted to finite element formulation using Galerkin technique and is validated with the results available from literature.

  15. Continuous dependence of solutions of abstract generalized linear differential equations with potential converging uniformly with a weight

    Czech Academy of Sciences Publication Activity Database

    Monteiro, Giselle Antunes; Tvrdý, Milan

    -, č. 71 (2014), s. 1-18. ISSN 1687-2770 R&D Projects: GA ČR(CZ) GA14-06958S Institutional support: RVO:67985840 Keywords : abstract generalized differential equation * continuous dependence * time scale dynamics Subject RIV: BA - General Mathematics Impact factor: 1.014, year: 2014 http://www.boundaryvalueproblems.com/content/2014/1/71

  16. Effect of laser beam non-uniformity and the AC stark shift on the two-photon resonant three-photon ionization process of the cesium atom

    International Nuclear Information System (INIS)

    The Ac Stark effect and the effect of laser beam non-uniformity on the two-photon resonant three-photon ionization spectrum of cesium is investigated. The non-uniformity due to the temporal and the spatial variations of the pumping laser makes the ionization spectrum non-symmetric and shifts the peak frequency of the excited-state population from the peak frequency of the ionization yield. The order of the non-linearity of the ionization process is also studied near resonances, and it is found that the minimum of the curve is close to the peak frequency of the excited-state spectrum. Ways of applying these results to studies of autoionizing states are suggested

  17. On the property of measurements with the PTW microLion chamber in continuous beams

    International Nuclear Information System (INIS)

    Purpose: The performance of liquid ionization chambers, which may prove to be useful tools in the field of radiation dosimetry, is based on several chamber and liquid specific characteristics. The present work investigates the performance of the PTW microLion liquid ionization chamber with respect to recombination losses and perturbations from ambient electric fields at various dose rates in continuous beams. Methods: In the investigation, experiments were performed using two microLion chambers, containing isooctane (C8H18) and tetramethylsilane [Si(CH3)4] as the sensitive media, and a NACP-02 monitor chamber. An initial activity of approximately 250 GBq 18F was employed as the radiation source in the experiments. The initial dose rate in each measurement series was estimated to 1.0 Gy min−1 by Monte Carlo simulations and the measurements were carried out during the decay of the radioactive source. In the investigation of general recombination losses, employing the two-dose-rate method for continuous beams, the liquid ionization chambers were operated at polarizing voltages 25, 50, 100, 150, 200, and 300 V. Furthermore, measurements were also performed at 500 V polarizing voltage in the investigation of the sensitivity of the microLion chamber to ambient electric fields. Results: The measurement results from the liquid ionization chambers, corrected for general recombination losses according to the two-dose-rate method for continuous beams, had a good agreement with the signal to dose linearity from the NACP-02 monitor chamber for general collection efficiencies above 70%. The results also displayed an agreement with the theoretical collection efficiencies according to the Greening theory, except for the liquid ionization chamber containing isooctane operated at 25 V. At lower dose rates, perturbations from ambient electric fields were found in the microLion chamber measurement results. Due to the perturbations, measurement results below an estimated dose rate of

  18. Quasi-continuous metasurface for ultra-broadband and polarization-controlled electromagnetic beam deflection

    Science.gov (United States)

    Wang, Yanqin; Pu, Mingbo; Zhang, Zuojun; Li, Xiong; Ma, Xiaoliang; Zhao, Zeyu; Luo, Xiangang

    2015-12-01

    Two-dimensional metasurface has attracted growing interest in recent years, owing to its ability in manipulating the phase, amplitude and polarization state of electromagnetic wave within a single interface. However, most existing metasurfaces rely on the collective responses of a set of discrete meta-atoms to perform various functionalities. In this paper, we presented a quasi-continuous metasurface for high-efficiency and broadband beam steering in the microwave regime. It is demonstrated both in simulation and experiment that the incident beam deviates from the normal direction after transmitting through the ultrathin metasurface. The efficiency of the proposed metasurface approximates to the theoretical limit of the single-layer metasurface in a broad frequency range, owing to the elimination of the circuit resonance in traditional discrete structures. The proposed scheme promises potential applications in broadband electromagnetic modulation and communication systems, etc.

  19. Maximum stiffness and minimum weight optimization of laminated composite beams using continuous fiber angles

    DEFF Research Database (Denmark)

    Blasques, José Pedro Albergaria Amaral; Stolpe, Mathias

    2011-01-01

    This paper deals with identification of optimal fiber orientations and laminate thicknesses in maximum stiffness and minimum weight design of laminated composite beams. The structural response is evaluated using beam finite elements which correctly account for the influence of the fiber orientation...... and cross section geometry. The resulting finite element matrices are significantly smaller than those obtained using equivalent finite element models. This modeling approach is therefore an attractive alternative in computationally intensive applications at the conceptual design stage where the focus...... is on the global structural response. An optimization strategy is presented which aims at enabling the use of fiber angles as continuous design variables albeit the problems may have many local minima. A sequence of closely related problems with an increasing number of design variables is treated. The design found...

  20. Quasi-continuous metasurface for ultra-broadband and polarization-controlled electromagnetic beam deflection

    Science.gov (United States)

    Wang, Yanqin; Pu, Mingbo; Zhang, Zuojun; Li, Xiong; Ma, Xiaoliang; Zhao, Zeyu; Luo, Xiangang

    2015-01-01

    Two-dimensional metasurface has attracted growing interest in recent years, owing to its ability in manipulating the phase, amplitude and polarization state of electromagnetic wave within a single interface. However, most existing metasurfaces rely on the collective responses of a set of discrete meta-atoms to perform various functionalities. In this paper, we presented a quasi-continuous metasurface for high-efficiency and broadband beam steering in the microwave regime. It is demonstrated both in simulation and experiment that the incident beam deviates from the normal direction after transmitting through the ultrathin metasurface. The efficiency of the proposed metasurface approximates to the theoretical limit of the single-layer metasurface in a broad frequency range, owing to the elimination of the circuit resonance in traditional discrete structures. The proposed scheme promises potential applications in broadband electromagnetic modulation and communication systems, etc. PMID:26635228

  1. Self-consistent beam halo studies ampersand halo diagnostic development in a continuous linear focusing channel

    International Nuclear Information System (INIS)

    Beam halos are formed via self-consistent motion of the beam particles. Interactions of single particles with time-varying density distributions of other particles are a major source of halo. Aspects of these interactions are studied for an initially equilibrium distribution in a radial, linear, continuous focusing system. When there is a mismatch, it is shown that in the self-consistent system, there is a threshold in space-charge and mismatch, above which a halo is formed that extends to ∼1.5 times the initial maximum mismatch radius. Tools are sought for characterizing the halo dynamics. Testing the particles against the width of the mismatch driving resonance is useful for finding a conservative estimate of the threshold. The exit, entering and transition times, and the time evolution of the halo, are also explored using this technique. Extension to higher dimensions is briefly discussed

  2. Design and beam test of a high intensity continuous wave RFQ accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhouli, E-mail: zhangzhouli@impcas.ac.cn; Sun, Liepeng; Jia, Huan; He, Yuan; Shi, Aimin; Du, Xiaonan; Wang, Jing; Jin, Xiaofeng; Pan, Gang; Xu, Xianbo; Li, Chenxing; Shi, Longbo; Lu, Liang; Zhang, Zimin; Wu, Junxia; Wang, Haoning; Zhu, Tieming; Wang, Xianwu; Guo, Yuhui; Liu, Yong; and others

    2014-11-01

    A four-vane continuous wave (CW) RFQ has been designed for the injector II LINAC of China ADS project. To acquire the experience of a CW RFQ on design, tuning, conditioning, running, etc., a 1-m-long RFQ accelerator prototype has been built. Working at 162.5 MHz, the RFQ prototype accelerates protons of 10 mA from 20 keV to 560 keV in one meter length with a low inter-vane voltage of 65 kV and a safe Kilpatric factor of 1.3. Conditioning and beam test of the accelerator prototype have been completed, and it shows the transmission efficiency can reach 90% with a 10 mA CW proton beam. Design, fabrication and tests of the RFQ prototype will be presented in detail in the paper.

  3. TDM/FM/FDMA - A modulation technique for multiple-beam satellites which precludes cochannel interference and allows non-uniform geographic distribution of user channels

    Science.gov (United States)

    Springett, J. C.

    The technique outlined in this paper is intended to eliminate the problems of cochannel interference and uniform geographic distribution of user channels which arise in conventional designs for a multiple spot beam communication satellite to serve mobile telephony users across the CONUS. By time multiplexing FM/FDMA signal ensembles so that only those beams operating on distinct frequency subbands are allowed to transmit concurrently, cochannel interference arising from simultaneous frequency subband reuse is precluded. Thus, time disjoint frequency reuse is accomplished over a repetitive sequence of fixed time slots. By assigning different size subbands to each time slot, a market of nonuniform users can be accommodated. The technique results in a greatly simplified antenna feed system design for the satellite, at a cost of imposing the need for time slot synchronization on the mobile FM receivers whose ability for rejecting adjacent channel interference is somewhat diminished.

  4. Economic and education impact of building the Continuous Electron Beam Accelerator Facility

    International Nuclear Information System (INIS)

    The Continuous Electron Beam Accelerator Facility (CEBAF) was built in Newport News, Virginia, between 1987 and 1995 and is a new basic research laboratory christened the Thomas Jefferson National Accelerator Facility (Jefferson Lab). Jefferson Lab's science and technology mission has major economic and educational benefits: basic research discoveries, improvement and application of key technologies associated with the accelerator and the experiments, extensive subcontracting with industry, and diverse employment and educational opportunities. The $600 million invested by federal, state, local and international partners to build Jefferson Lab has had substantial economic and educational benefits locally, as well as significant benefits distributed among industries and universities throughout the United States

  5. CEBAF/SURA [Continuous Electron Beam Accelerator Facility]/[Southeastern Universities Research Association] 1988 summer workshop

    International Nuclear Information System (INIS)

    This report contains papers from a summer workshop of the continuous electron beam accelerator facility. Some topics of these papers are: spectrometers; electron scattering from deuterons; relativistic correlations in nuclear matter; pion production on 3He and 3H; quantum electrodynamic processes in crystals; 12C(e,e'p) x reaction; deuteron polarization tensor and relativistic spin rotation; electromagnetic excitation of nuclei; electron distortion and structure functions in (e,e'p) reactions; and reaction mechanism of 4He(e,e'p)3H

  6. Off-axis dose equivalent due to secondary neutrons from uniform scanning proton beams during proton radiotherapy

    International Nuclear Information System (INIS)

    The production of secondary neutrons is an undesirable byproduct of proton therapy and it is important to quantify the contribution from secondary neutrons to patient dose received outside the treatment volume. The purpose of this study is to investigate the off-axis dose equivalent from secondary neutrons experimentally using CR-39 plastic nuclear track detectors (PNTD) at ProCure Proton Therapy Center, Oklahoma City, OK. In this experiment, we placed several layers of CR-39 PNTD laterally outside the treatment volume inside a phantom and in air at various depths and angles with respect to the primary beam axis. Three different proton beams with max energies of 78, 162 and 226 MeV and 4 cm modulation width, a 5 cm diameter brass aperture, and a small snout located 38 cm from isocenter were used for the entire experiment. Monte Carlo simulations were also performed based on the experimental setup using a simplified snout configuration and the FLUKA Monte Carlo radiation transport code. The measured ratio of secondary neutron dose equivalent to therapeutic primary proton dose (H/D) ranged from 0.3 ± 0.08 mSv Gy−1 for 78 MeV proton beam to 37.4 ± 2.42 mSv Gy−1 for 226 MeV proton beam. Both experiment and simulation showed a similar decreasing trend in dose equivalent with distance to the central axis and the magnitude varied by a factor of about 2 in most locations. H/D was found to increase as the energy of the primary proton beam increased and higher H/D was observed at 135° compared to 45° and 90°. The overall higher H/D in air indicates the predominance of external neutrons produced in the nozzle rather than inside the body. (paper)

  7. Seismic Performance of RC Beam-Column Connections with Continuous Rectangular Spiral Transverse Reinforcements for Low Ductility Classes

    OpenAIRE

    Mohammadamin Azimi; Azlan Bin Adnan; Abdul Rahman Bin Mohd Sam; Mahmood Md Tahir; Iman Faridmehr; Reza Hodjati

    2014-01-01

    The seismic performance of RC columns could be significantly improved by continuous spiral reinforcement as a result of its adequate ductility and energy dissipation capacity. Due to post-earthquake brittle failure observations in beam-column connections, the seismic behaviour of such connections could greatly be improved by simultaneous application of this method in both beams and columns. In this study, a new proposed detail for beam to column connection introduced as “twisted opposing rect...

  8. Helicopter downwash measured by continuous-wave Doppler lidars with agile beam steering

    DEFF Research Database (Denmark)

    Sjöholm, Mikael; Angelou, Nikolas; Hansen, Per;

    2012-01-01

    A ground-based remote sensing short-range WindScanner with agile beam steering based on a modified ZephIR continuous-wave wind lidar (LIght Detection And Ranging) and a double prism arrangement has recently been developed at the Department of Wind Energy at the DTU Risø campus. The WindScanner me......A ground-based remote sensing short-range WindScanner with agile beam steering based on a modified ZephIR continuous-wave wind lidar (LIght Detection And Ranging) and a double prism arrangement has recently been developed at the Department of Wind Energy at the DTU Risø campus. The Wind......Scanner measures the line-of-sight component of the wind and by rapid steering of the line-of-sight and the focus position, all locations within a cone with a full top angle of 120 can be reached from about 8 meters out to some hundred meters depending on the range resolution needed. By using three such Wind...

  9. Production of multi-, oligo- and single-pore membranes using a continuous ion beam

    Science.gov (United States)

    Apel, P. Yu.; Ivanov, O. M.; Lizunov, N. E.; Mamonova, T. I.; Nechaev, A. N.; Olejniczak, K.; Vacik, J.; Dmitriev, S. N.

    2015-12-01

    Ion track membranes (ITM) have attracted significant interest over the past two decades due to their numerous applications in physical, biological, chemical, biochemical and medical experimental works. A particular feature of ITM technology is the possibility to fabricate samples with a predetermined number of pores, including single-pore membranes. The present report describes a procedure that allowed for the production of multi-, oligo- and single-pore membranes using a continuous ion beam from an IC-100 cyclotron. The beam was scanned over a set of small diaphragms, from 17 to ∼1000 μm in diameter. Ions passed through the apertures and impinged two sandwiched polymer foils, with the total thickness close to the ion range in the polymer. The foils were pulled across the ion beam at a constant speed. The ratio between the transport speed and the scanning frequency determined the distance between irradiation spots. The beam intensity and the aperture diameters were adjusted such that either several, one or no ions passed through the diaphragms during one half-period of scanning. After irradiation, the lower foil was separated from the upper foil and was etched to obtain pores 6-8 μm in diameter. The pores were found using a color chemical reaction between two reagents placed on opposite sides of the foil. The located pores were further confirmed using SEM and optical microscopy. The numbers of tracks in the irradiation spots were consistent with the Poisson statistics. Samples with single or few tracks obtained in this way were employed to study fine phenomena in ion track nanopores.

  10. The influence of physical wedges on penumbra and in-field dose uniformity in ocular proton beams.

    Science.gov (United States)

    Baker, Colin; Kacperek, Andrzej

    2016-04-01

    A physical wedge may be partially introduced into a proton beam when treating ocular tumours in order to improve dose conformity to the distal border of the tumour and spare the optic nerve. Two unwanted effects of this are observed: a predictable broadening of the beam penumbra on the wedged side of the field and, less predictably, an increase in dose within the field along a relatively narrow volume beneath the edge (toe) of the wedge, as a result of small-angle proton scatter. Monte Carlo simulations using MCNPX and direct measurements with radiochromic (GAFCHROMIC(®) EBT2) film were performed to quantify these effects for aluminium wedges in a 60 MeV proton beam as a function of wedge angle and position of the wedge relative to the patient. For extreme wedge angles (60° in eye tissue) and large wedge-to-patient distances (70 mm in this context), the 90-10% beam penumbra increased from 1.9 mm to 9.1 mm. In-field dose increases from small-angle proton scatter were found to contribute up to 21% additional dose, persisting along almost the full depth of the spread-out-Bragg peak. Profile broadening and in-field dose enhancement are both minimised by placing the wedge as close as possible to the patient. Use of lower atomic number wedge materials such as PMMA reduce the magnitude of both effects as a result of a reduced mean scattering angle per unit energy loss; however, their larger physical size and greater variation in density are undesirable. PMID:26988936

  11. Redistribution effects in linear elastic analyses of continuous composite steel-concrete beams according to Eurocode 4

    Directory of Open Access Journals (Sweden)

    Kostić Svetlana M.

    2011-01-01

    Full Text Available Different analytical methods, with different levels of approximations and accuracy, are available for analysis of continuous composite steel-concrete beams. The Eurocode 4 recommends few simple methods for calculation of creep, shrinkage, cracking of concrete and shear lag effects that are explained in the paper. Through the numerical examples of four continuous composite steel-concrete beams, the proposed methods of analyses are evaluated and compared. Practical recommendations for analysis of this type of girders are formulated.

  12. Coherent frequency-modulated continuous wave reflectometry for measuring stationary Brillouin grating induced under uniform pumping by counterpropagating nonmodulated light waves.

    Science.gov (United States)

    Takada, Kazumasa; Yasuno, Takahiro

    2016-05-20

    We describe theoretically and experimentally how valuable information on the distributed Brillouin spectra of an optical waveguide is derived from the stationary Brillouin grating measurement under uniform pumping over the waveguide by using the coherent frequency-modulated continuous wave reflectometry. We upconvert the frequencies of the probe and pumping light waves by the Brillouin frequency with one modulator and detect the Stokes light in the same way that we detect the Fresnel and Rayleigh backreflections in the fiber. The intrinsic coherent spike is reduced by using the lock-in detection and the least squares method to reveal the distributed Brillouin spectra of a short optical fiber consisting of two different fibers spliced together. PMID:27411124

  13. Assessment of uniform temperature assumption in zoning on the numerical simulation of a walking beam reheating furnace

    International Nuclear Information System (INIS)

    The numerical simulation of the heating process of steel slabs in a walking beam reheating furnace is reported using two different models. In one model, the turbulent reactive flow in the furnace is simulated together with the heat conduction in the slabs. The calculations are performed using a commercial code and a user-defined function is used to simulate the periodic movement of the slabs by the walking beams in the furnace. Unsteady calculations are performed until a periodic transient solution is achieved. In the second model, the furnace is divided into a small number of zones and the average temperature and chemical composition are prescribed in every zone based on the results of the first model. The unsteady heating process of the slabs is modeled using the same software and accounting for radiative transfer in the furnace and heat conduction in the slabs. The results of the first model are taken as a benchmark for the second one. It is shown that the first model predicts radiative heat fluxes and temperatures of the slabs that are consistent with previous work. The two models yield volume average temperatures of the slabs leaving the furnace that differ by less than 3%, provided that accurate values of the temperature of the gases and walls are used. The second model is computationally more economical, requiring only about 5% of the computational time of the first one. - Highlights: • The heating process of steel slabs in a reheating furnace is numerically simulated. • Unsteady calculations accounting for the periodic movement of the slabs are reported. • We compare two models differing on how the thermochemical composition is obtained. • The models predict mean slab temperatures at the exit that differ by less than 3%. • The computational time of the fastest model is only about 5% of the slowest one

  14. Continuous electropolishing of Hastelloy substrates for ion-beam assisted deposition of MgO

    Energy Technology Data Exchange (ETDEWEB)

    Kreiskott, Sascha; Arendt, Paul N; Bronisz, Lawrence E; Foltyn, Steve R; Matias, Vladimir [Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2003-05-01

    We demonstrate the applicability of continuous electropolishing for the preparation of metal tapes for ion-beam assisted deposition of MgO for the fabrication of in-plane textured template layers. These templates are used for the fabrication of second generation high temperature superconducting wires utilizing YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} coatings on metallic substrates. Surface roughness values below 1 nm and local slopes of less than 1 deg. could be achieved with the electropolishing process. Mean surface roughness values are lower with the use of electropolishing and slopes of surface roughness inclines are significantly reduced compared to the best results of mechanical polishing (3.5 nm and 5 deg., respectively). The cost-effective process of electropolishing shows great promise for the fabrication of second generation high temperature superconducting wire.

  15. Continuous electropolishing of Hastelloy substrates for ion-beam assisted deposition of MgO

    International Nuclear Information System (INIS)

    We demonstrate the applicability of continuous electropolishing for the preparation of metal tapes for ion-beam assisted deposition of MgO for the fabrication of in-plane textured template layers. These templates are used for the fabrication of second generation high temperature superconducting wires utilizing YBa2Cu3O7-δ coatings on metallic substrates. Surface roughness values below 1 nm and local slopes of less than 1 deg. could be achieved with the electropolishing process. Mean surface roughness values are lower with the use of electropolishing and slopes of surface roughness inclines are significantly reduced compared to the best results of mechanical polishing (3.5 nm and 5 deg., respectively). The cost-effective process of electropolishing shows great promise for the fabrication of second generation high temperature superconducting wire

  16. A mechanical chopper with continuously adjustable duty cycle for a wide X-ray beam

    International Nuclear Information System (INIS)

    The prototype of a fast beam chopper for hard X-rays, with a continuously variable duty cycle from less than 10 to more than 90% has been successfully developed, built and tested. The apparatus consists in 12 planetary stainless-steel blades that are 100 mm wide and are mounted on two large discs. All blades are kept permanently parallel to each other, thanks to a gear system, which also allows changing their orientation. The two main parameters of the chopper (duty cycle and chopping frequency) are controlled independently and remotely. In the present design, the device allows chopping frequencies ranging from 0 to 300 Hz. The principle of operation, preliminary results of the instrument's performance and an example demonstrating the capacity of the system for image quality improvement and X-ray dose reduction at the specimen are presented

  17. Report on selected concerns regarding property accountability at the Continuous Electron Beam Accelerator facility

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-24

    The Continuous Electron Beam Accelerator Facility (CEBAF) is a federally funded research and development center at Newport News, Virginia, At the time of our review, Southeastern Universities Research Association (SURA) was operating CEBAF for the Department of Energy (DOE) under a management and operating (M&O) contract administered by DOE`s Oak Ridge Operations Office. SURA is currently operating CEBAF under a performance based management contract, The purpose of our inspection was to evaluate selected management issues regarding property accountability at CEBAF that we identified as a result of a complaint received by the Office of Inspector General. The complainant alleged a lack of accountability for Government equipment at CEBAF and the lack of an equipment inventory. Specifically, the complainant alleged, among other things, that after a named supervisor departed, CEBAF personnel had no idea what equipment had been assigned to the supervisor and could not account for any missing materials.

  18. Dual focused coherent beams for three-dimensional optical trapping and continuous rotation of metallic nanostructures

    Science.gov (United States)

    Xu, Xiaohao; Cheng, Chang; Zhang, Yao; Lei, Hongxiang; Li, Baojun

    2016-01-01

    Metallic nanoparticles and nanowires are extremely important for nanoscience and nanotechnology. Techniques to optically trap and rotate metallic nanostructures can enable their potential applications. However, because of the destabilizing effects of optical radiation pressure, the optical trapping of large metallic particles in three dimensions is challenging. Additionally, the photothermal issues associated with optical rotation of metallic nanowires have far prevented their practical applications. Here, we utilize dual focused coherent beams to realize three-dimensional (3D) optical trapping of large silver particles. Continuous rotation of silver nanowires with frequencies measured in several hertz is also demonstrated based on interference-induced optical vortices with very low local light intensity. The experiments are interpreted by numerical simulations and calculations. PMID:27386838

  19. Discharge current and current of supershort avalanche E-beam at volume nanosecond discharge in non-uniform electric field

    Science.gov (United States)

    Tarasenko, Victor F.; Rybka, Dmitrii V.; Baksht, Evgenii H.; Kostyrya, Igor'D.; Lomaev, Mikhail I.

    2008-01-01

    The gas diode current-voltage characteristics at the voltage pulses applied from the RADAN and SM-3NS pulsers, and generation of an supershort avalanche electron beam (SAEB) have been studied experimentally in an inhomogeneous electric field upon a nanosecond breakdown in an air gap at atmospheric pressure. Displacement currents with amplitude over 1 kA have been observed and monitored. It is shown that the displacement current amplitude gets increased due to movement of the dense plasma front and charging of a "capacitor" formed between plasma and anode. The SAEB generation time relatively to the discharge current pulses and the gap voltage were determined in the experiments. It is shown that the SAEB current maximum at the pulser voltages of hundreds kV is registered on the discharge current pulse front, before the discharge current peak of the gas diode capacitance, and the delay time of these peaks is determined by the value of an interelectrode spacing. The delay time in case of a gap of 16 mm and air breakdown at atmospheric pressure was ~100 ps, and in case of 10 mm it was less than 50 ps.

  20. Early Commissioning Experience and Future Plans for the 12 GeV Continuous Electron Beam Accelerator Facility

    Energy Technology Data Exchange (ETDEWEB)

    Spata, Michael F. [JLAB

    2014-12-01

    Jefferson Lab has recently completed the accelerator portion of the 12 GeV Upgrade for the Continuous Electron Beam Accelerator Facility. All 52 SRF cryomodules have been commissioned and operated with beam. The initial beam transport goals of demonstrating 2.2 GeV per pass, greater than 6 GeV in 3 passes to an existing experimental facility and greater than 10 GeV in 5-1/2 passes have all been accomplished. These results along with future plans to commission the remaining beamlines and to increase the performance of the accelerator to achieve reliable, robust and efficient operations at 12 GeV are presented.

  1. Updated analytical solutions of continuity equation for electron beams precipitation - II. Mixed energy losses

    Science.gov (United States)

    Zharkova, V. V.; Dobranskis, R. R.

    2016-06-01

    In this paper we consider simultaneous analytical solutions of continuity equations for electron beam precipitation (a) in collisional losses and (b) in ohmic losses, or mixed energy losses (MEL) by applying the iterative method to calculate the resulting differential densities at given precipitation depth. The differential densities of precipitating electrons derived from the analytical solutions for MELs reveal increased flattening at energies below 10-30 keV compared to a pure collisional case. This flattening becomes stronger with an increasing precipitation depth turning into a positive slope at greater precipitation depths in the chromosphere resulting in a differential density distribution with maximum that shifts towards higher energies with increase in column depth, while the differential densities combining precipitating and returning electrons are higher at lower energies than those for a pure collisional case. The resulting hard X-ray (HXR) emission produced by the beams with different initial energy fluxes and spectral indices is calculated using the MEL approach for different ratios between the differential densities of precipitating and returning electrons. The number of returning electrons can be even further enhanced by a magnetic mirroring, not considered in the present model, while dominating at lower atmospheric depths where the magnetic convergence and magnitude are the highest. The proposed MEL approach provides an opportunity to account simultaneously for both collisional and ohmic losses in flaring events, which can be used for a quick spectral fitting of HXR spectra and evaluation of a fraction of returning electrons versus precipitating ones. The semi-analytical MEL approach is used for spectral fitting to Reuven High Energy Solar Spectroscopic Imager observations of nine C, M and X class flares revealing a close fit to the observations and good resemblance to numerical FP solutions.

  2. Analysis of late toxicity associated with external beam radiation therapy for prostate cancer with uniform setting of classical 4-field 70 Gy in 35 fractions: a survey study by the Osaka Urological Tumor Radiotherapy Study Group

    OpenAIRE

    Yoshioka, Yasuo; Suzuki, Osamu; Nishimura, Kazuo; Inoue, Hitoshi; Hara, Tsuneo; Yoshida, Ken; Imai, Atsushi; Tsujimura, Akira; Nonomura, Norio; Ogawa, Kazuhiko

    2012-01-01

    We aimed to analyse late toxicity associated with external beam radiation therapy (EBRT) for prostate cancer using uniform dose-fractionation and beam arrangement, with the focus on the effect of 3D (CT) simulation and portal field size. We collected data concerning patients with localized prostate adenocarcinoma who had been treated with EBRT at five institutions in Osaka, Japan, between 1998 and 2006. All had been treated with 70 Gy in 35 fractions, using the classical 4-field technique wit...

  3. Environmental Management Assessment of the Continuous Electron Beam Accelerator Facility (CEBAF)

    Energy Technology Data Exchange (ETDEWEB)

    1993-03-01

    This report documents the results of the Environmental Management Assessment performed at the Continuous Electron Beam Accelerator Facility (CEBAF) in Newport News, Virginia. During this assessment, activities and records were reviewed and interviews were conducted with personnel from the CEBAF Site Office; the CEBAF management and operating contractor (M&O), Southeastern Universities Research Association, Inc. (SURA); the Oak Ridge Field Office (OR); and the responsible DOE Headquarters Program Office, the Office of Energy Research (ER). The onsite portion of the assessment was conducted from March 8 through March 19, 1993, by the US Department of Energy`s (DOE`s) Office of Environmental Audit (EH-24) located within the office of Environment, Safety and Health (EH). DOE 5482.1 B, ``Environment, Safety and Health Appraisal Program,`` and Secretary of Energy Notice (SEN)-6E-92, ``Departmental Organizational and Management Arrangements,`` establish the mission of EH-24 to provide comprehensive, independent oversight of Department-wide environmental programs on behalf of the Secretary of Energy. The ultimate goal of EH-24 is enhancement of environmental protection and minimization of risk to public health and the environment. EH-24 accomplishes its mission utilizing systematic and periodic evaluations of the Department`s environmental programs within line organizations, and through use of supplemental activities which serve to strengthen self-assessment and oversight functions within program, field, and contractor organizations.

  4. Ion-recombination correction factor κsat for spherical ion chambers irradiated by continuous photom beams

    International Nuclear Information System (INIS)

    The large range of reference air kerma rates of brachytherapy sources involves the use of large-volume ionization chambers. When such ionization chambers are used the ion-recombination correction factor ksat has to be determined. In this paper three spherical ion chambers with volume ranging from 30 to 104 cm3 have been irradiated by photons of a 192Ir source to determine the ksat factors. The ionization currents of the ion chambers as a function of the applied voltage and the air kerma rate have been analysed to determine the contribution of the initial and general ion recombination. The ksat values for large-volume ionization chambers obtained by considering the general ion recombination as predominant (Almond's approach) are in disagreement with the results obtained using methods that consider both initial and general ion-recombination contributions (Niatel's approach). Such disagreement can reach 0.7% when high currents are measured for a high-activity source calibration in terms of reference air kerma rate. In this study a new 'two-voltage' method, independent of the voltage ratio given by a dosimetry system, is proposed for practical dosimetry of continuous x-and gamma-radiation beams. In the case where the Almond approach is utilized, the voltage ratio V1/V2 should be less than 2 instead of Almond's limit of V1/V2 <5. (Author)

  5. Environmental Management Assessment of the Continuous Electron Beam Accelerator Facility (CEBAF)

    International Nuclear Information System (INIS)

    This report documents the results of the Environmental Management Assessment performed at the Continuous Electron Beam Accelerator Facility (CEBAF) in Newport News, Virginia. During this assessment, activities and records were reviewed and interviews were conducted with personnel from the CEBAF Site Office; the CEBAF management and operating contractor (M ampersand O), Southeastern Universities Research Association, Inc. (SURA); the Oak Ridge Field Office (OR); and the responsible DOE Headquarters Program Office, the Office of Energy Research (ER). The onsite portion of the assessment was conducted from March 8 through March 19, 1993, by the US Department of Energy's (DOE's) Office of Environmental Audit (EH-24) located within the office of Environment, Safety and Health (EH). DOE 5482.1 B, ''Environment, Safety and Health Appraisal Program,'' and Secretary of Energy Notice (SEN)-6E-92, ''Departmental Organizational and Management Arrangements,'' establish the mission of EH-24 to provide comprehensive, independent oversight of Department-wide environmental programs on behalf of the Secretary of Energy. The ultimate goal of EH-24 is enhancement of environmental protection and minimization of risk to public health and the environment. EH-24 accomplishes its mission utilizing systematic and periodic evaluations of the Department's environmental programs within line organizations, and through use of supplemental activities which serve to strengthen self-assessment and oversight functions within program, field, and contractor organizations

  6. A correlated study between effective total macroscopic cross sections and effective energies for neutron beams with continuous spectra

    CERN Document Server

    Kobayashi, H

    1999-01-01

    Two practically useful quantities have been introduced to characterize a continuous-energy-spectrum neutron beam and to describe transmission phenomena of the beam in the field of quantitative neutron radiography. These quantities are the effective energy instead of a peak energy or a mean energy of the spectrum and an effective total macroscopic (ETM) cross section instead of a total macroscopic (TM) cross section as defined for a monochromatic energy. Four neutron beams have been used to measure ETM cross sections at effective energies of 29.8, 17.2, 9.8 meV, and at the In resonance energy of 1.46 eV. Results are studied as a function of estimated effective energy, where the effective energy was estimated by a beam quality indicator (BQI) which has been proposed recently. Validity of ETM cross sections as a function of the effective energy is discussed and correlated with recent nuclear data.

  7. Design of a Second Harmonic Double-Beam Continuous Wave Gyrotron with Operating Frequency of 0.79 THz

    Science.gov (United States)

    Manuilov, V. N.; Glyavin, M. Yu; Sedov, A. S.; Zaslavsky, V. Yu; Idehara, T.

    2015-12-01

    This paper presents the most essential steps of a design study of a novel second harmonic gyrotron operating in CW (continuous wave) regime at a frequency of 0.79 THz and an output power of 1-100 W. It is based on a novel idea for suppression of the parasitic modes using a double-beam electron-optical system (EOS). It includes a triode magnetron injection gun (MIG), which forms two high-quality helical electron beams (HEB). Different schemes, namely one with two generating beams and another with one generating and one absorbing beam, have been investigated and compared. It has been shown that the scheme with two generating beams is more advantageous since it allows an effective suppression of the parasitic modes and a stable single-mode operation at the second harmonic resonance. A MIG which is appropriate for the realization of the latter scheme has been optimized using numerical codes for computer-aided design (CAD). It forms beams with practically equal pitch factors and moderate velocity spread. The construction of the gun is not sensitive to small misalignments and shifts of the electrodes and the magnetic field. Among the most promising characteristics of the presented design are an improved mode selection and a stable single-mode generation at currents that are two to three times higher than the currents in the single-beam (i.e., conventional) gyrotrons.

  8. Experimental investigations on continuous glass-GFRP beams : preliminary nonlinear numerical modelling

    OpenAIRE

    Valarinho, Luís; Correia, João R.; Branco, Fernando A.; Sena-Cruz, José

    2012-01-01

    This paper describes results of experimental and numerical investigations about the structural behaviour of composite beams made of annealed glass panes and GFRP pultruded profiles. A brief description of flexural tests previously carried out on simply supported glass and glass-GFRP composite beams is first presented. Then, results of flexural tests on two-span glass-GFRP composite beams, bonded with three different structural adhesives, are described in detail. Finally, a preliminary numeric...

  9. Influence of growth transients on interface and composition uniformity of ultra thin In(As,P) and (In,Al,Ga)As epilayers grown by chemical beam epitaxy

    International Nuclear Information System (INIS)

    In this work, measurements of epitaxial growth rate transients for multiple quantum wells (MQWs) in chemical beam epitaxy (CBE) have been made. Mass spectrometry measurements of typical growth conditions were made of gas source species of the InAsxP1-x/InP system, while reflection high-energy electron diffraction (RHEED) measurements were made for the GaAs/AlxGa1-xAs and InxGa1-xAs/GaAs systems. The results of these experiments went directly into predicting the transient growth rate of thin layers for multi-quantum well photovoltaic devices. The data obtained using these techniques resulted in an improved growth interruption sequence for MQW structures in the InAsxP1-x/InP system. Improvements in overall material quality have been observed by high resolution X-ray diffraction (HRXRD). HRXRD measurements of the InAsxP1-x/InP structures yield sharp satellite peaks revealing the possibility of achieving nearly perfect interfaces. From low temperature photoluminescence, narrow emission linewidths from quantum wells indicate an enhanced compositional uniformity, and room temperature photocurrent spectroscopy reveals an improvement in device performance

  10. Impacts of Continuous Electron Beam Accelerator Facility operations on groundwater and surface water: Appendix 9

    International Nuclear Information System (INIS)

    The operation of the proposed Continuous Electron Beam Accelerator Facility (CEBAF) at Newport News, Virginia, is expected to result in the activation and subsequent contamination of water resources in the vicinity of the accelerator. Since the proposed site is located in the headwaters of the watershed supplying Big Bethel Reservoir, concern has been expressed about possible contamination of water resources used for consumption. Data characterizing the surface water and groundwater regime in the site area are limited. A preliminary geotechnical investigation of the site has been completed (LAW 1985). This investigation concluded that groundwater flow is generally towards the southeast at an estimated velocity of 2.5 m/y. This conclusion is based on groundwater and soil boring data and is very preliminary in nature. This analysis makes use of the data and conclusions developed during the preliminary geotechnical investigation to provide an upper-bound assessment of radioactive contamination from CEBAF operations. A site water balance was prepared to describe the behavior of the hydrologic environment that is in close agreement with the observed data. The transport of contamination in the groundwater regime is assessed using a one-dimensional model. The groundwater model includes the mechanisms of groundwater flow, groundwater recharge, radioactive decay, and groundwater activation. The model formulation results in a closed-form, exact, analytic solution of the concentration of contamination in the groundwater. The groundwater solution is used to provide a source term for a surface-water analysis. The surface-water and groundwater models are prepared for steady state conditions such that they represent conservative evaluations of CEBAF operations

  11. Fabrication of 3D nanoimprint stamps with continuous reliefs using dose-modulated electron beam lithography and thermal reflow

    International Nuclear Information System (INIS)

    3D electron beam lithography and thermal reflow were combined to fabricate structures with multilevel and continuous profiles. New shapes, smooth surfaces and sharp corners were achieved. By using exposure with variable doses, up to 20 steps were fabricated in a 500 nm thick resist with a lateral resolution of 200 nm. Steps were reflowed into continuous slopes by thermal post-processing, and were transferred into silicon substrates by proportional plasma etching. The method can be used for the fabrication of 3D nanoimprint stamps with both sharp features and continuous profiles.

  12. Topologies of (strong) uniform convergence on bornologies

    OpenAIRE

    Holá, Lubica; Novotný, Branislav

    2012-01-01

    We continue the study of topologies of strong uniform convergence on bornologies initiated in [G. Beer and S. Levi, Strong uniform continuity, J. Math Anal. Appl., 350:568-589, 2009] and [G. Beer and S. Levi, Uniform continuity, uniform convergence and shields, Set-Valued and Variational Analysis, 18:251-275, 2010]. We study cardinal invariants of topologies of (strong) uniform convergence on bornologies on the space of continuous real-valued functions and we also generalize some known result...

  13. Continuous Beam Steering From A Segmented Liquid Crystal Optical Phased Array

    Science.gov (United States)

    Pouch, John; Nguyen, Hung; Miranda, Felix; Titus, Charles M.; Bos, Philip J.

    2002-01-01

    Optical communications to and from deep space probes will require beams possessing divergence on the order of a microradian, and must be steered with sub-microradian precision. Segmented liquid crystal spatial phase modulators, a type of optical phased array, are considered for this ultra-high resolution beam steering. It is shown here that in an ideal device of this type, there are ultimately no restrictions on the angular resolution. Computer simulations are used to obtain that result, and to analyze the influence of beam truncation and substrate flatness on the performance of this type of device.

  14. Investigation of the influence of extra noises in seed beams on continuous-variable entanglement generation

    Institute of Scientific and Technical Information of China (English)

    Shang Ya-Na; Yan Zhi-Hui; Jia Xiao-Jun; Su Xiao-Long; Xie Chang-De

    2011-01-01

    The influence of the extra classical noises in seed beams on the entanglement between the signal and the idler modes of the output fields generated by a non-degenerate optical parametric amplifier operating at deamplification is investigated theoretically and experimentally. With the increase of the extra classical noises in the seed beams, the correlation degree of the output entangled optical fields, which is scaled by the quantum noise limit, decreases rapidly. The experimental results are in good agreement with the theoretical calculations.

  15. Analysis of Warren and X-trussed continuous beam by equivalent stiffness matrices and moments of inertia

    International Nuclear Information System (INIS)

    This work study the resolution of Warren and X-trussed continuous beams using equivalent stiffness coefficients and moments of inertia. The equilibrium equations in the generic Joint r are obtained by finite differences method and the deflections and arbitrary static load equations are present in finite Fourier series form. The results of illustrative examples for both kinds of trussed be beams are compared with solutions obtained with the Lorane Linear Program. The influence of panels number and comparisions with classic result of equivalent inertia are established. Abacus for X-trussed beams for stiffness coefficients obtained by series versus equivalent inertia stiffness coefficients and corrections using the top and bottom chords area are presented. (Author)

  16. Comparison of the PIC model and the Lie algebraic metnod in the simulation of intense continuous beam transport

    Institute of Scientific and Technical Information of China (English)

    ZHAO xiao-Song; L(U) Jian-Qin

    2009-01-01

    Both the PIC(Particle-In-Cell) model and the Lie algebraic method can be used to simulate the transport of intense continuous beams.The PIC model is to calculate the space charge field,which is blended into the external field,and then simulate the trajectories of particles in the total field;the Lie algebraic method is to simulate the intense continuous beam transport with transport matrixes.Two simulation codes based on the two methods are developed respectively,and the simulated results of transport in a set of electrostatic lenses are compared.It is found that the results from the two codes are in agreement with each other.and both approaches have their own merits.

  17. Thermionic gun control system for the CEBAF [Continuous Electron Beam Accelerator Facility] injector

    International Nuclear Information System (INIS)

    The injector for the CEBAF accelerator must produce a high-quality electron beam to meet the overall accelerator specifications. A Hermosa electron gun with a 2 mm-diameter cathode and a control aperture has been chosen as the electron source. This must be controlled over a wide range of operating conditions to meet the beam specifications and to provide flexibility for accelerator commissioning. The gun is controlled using Computer Automated Measurement and Control (CAMAC IEEE-583) technology. The system employs the CAMAC-based control architecture developed at CEBAF. The control system has been tested, and early operating data on the electron gun and the injector beam transport system has been obtained. This system also allows gun parameters to be stored at the operator location, without paralyzing operation. This paper describes the use of this computer system in the control of the CEBAF electron gun. 2 refs., 6 figs., 1 tab

  18. The CEBAF [Continuous Electron Beam Accelerator Facility] superconducting accelerator: An overview

    International Nuclear Information System (INIS)

    The CEBAF accelerator is a CW linac based on rf superconductivity and making use of multiple recirculation. Its major components are a 50 MeV injector, two linac segments of 0.5 GeV energy gain each, and recirculator arcs connecting the two linac segments. Each linac segment consists of 25 cryomodules, separated by warm sections with quadrupoles, steering magnets, and beam diagnostics. Each cryomodule contains 8, 1500 MHz, 5-cell, Cornell type cavities with waveguide couplers for fundamental power and HOM damping, each cavity being powered by its own klystron. Recirculator arcs are vertically stacked, large radius, strong focusing beam lines that minimize synchrotron radiation effects. A high quality (ΔE/E ∼ 10-4, ε ∼ 10-9 m) beam of 200μA, 100% duty factor, with 0.5 GeV ≤ E ≤ 4.0 GeV will be generated

  19. Nonlinear deformation of a cantilever incompressible poroelastic beam under a uniform load%均布载荷作用下悬臂不可压饱和多孔梁的非线性变形

    Institute of Scientific and Technical Information of China (English)

    杨骁; 蔡赟姝

    2008-01-01

    Nonlinear bending of cantilever incompressible poroelastic beams subjected to a uniform load is investigated with the constraint that fluid flow is only in the axial direction. The governing equations for large deflection of the poroelastic beam are derived from theory of incompressible saturated porous media. Then, nonlinear responses of a cantilever beam with impermeable fixed end and permeable free end are examined with the Galerkin truncation method. The deflections and bending moments of the poroelastie beam and the equivalent couples of the pore fluid pressures are shown in figures. The differences of the results between the large deflection and the small deflection theories are analyzed. It is shown that the results of the large deflection theory are smaller than those of the small deflection theory, and the time needed to approach their stationary states for the large deflection theory is shorter than that for the small deflection theory.

  20. Finite element modeling of light propagation in fruit under illumination of continuous-wave beam

    Science.gov (United States)

    Spatially-resolved spectroscopy provides a means for measuring the optical properties of biological tissues, based on analytical solutions to diffusion approximation for semi-infinite media under the normal illumination of infinitely small size light beam. The method is, however, prone to error in m...

  1. Production of multi-, oligo- and single-pore membranes using a continuous ion beam

    Czech Academy of Sciences Publication Activity Database

    Apel, P. Yu.; Ivanov, O.; Lizunov, N. E.; Mamonova, T. I.; Nechaev, A. N.; Olejniczak, K.; Vacík, Jiří; Dmitriev, S. N.

    2015-01-01

    Roč. 365, DEC (2015), s. 641-645. ISSN 0168-583X R&D Projects: GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : ion beam * irradiation * ion track * etching * single nanopore Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.124, year: 2014

  2. Uniformity calibration for ICT image

    International Nuclear Information System (INIS)

    The uniformity of ICT image is impaired by beam hardening and the inconsistency of detector units responses. The beam hardening and the nonlinearity of the detector's output have been analyzed. The correction factors are determined experimentally by the detector's responses with different absorption length. The artifacts in the CT image of a symmetrical aluminium cylinder have been eliminated after calibration. (author)

  3. Seismic Performance of RC Beam-Column Connections with Continuous Rectangular Spiral Transverse Reinforcements for Low Ductility Classes

    Directory of Open Access Journals (Sweden)

    Mohammadamin Azimi

    2014-01-01

    Full Text Available The seismic performance of RC columns could be significantly improved by continuous spiral reinforcement as a result of its adequate ductility and energy dissipation capacity. Due to post-earthquake brittle failure observations in beam-column connections, the seismic behaviour of such connections could greatly be improved by simultaneous application of this method in both beams and columns. In this study, a new proposed detail for beam to column connection introduced as “twisted opposing rectangular spiral” was experimentally and numerically investigated and its seismic performance was compared against normal rectangular spiral and conventional shear reinforcement systems. In this study, three full scale beam to column connections were first designed in conformance with Eurocode (EC2-04 for low ductility class connections and then tested by quasistatic cyclic loading recommended by ACI Building Code (ACI 318-02. Next, the experimental results were validated by numerical methods. Finally, the results revealed that the new proposed connection could improve the ultimate lateral resistance, ductility, and energy dissipation capacity.

  4. Seismic performance of RC beam-column connections with continuous rectangular spiral transverse reinforcements for low ductility classes.

    Science.gov (United States)

    Azimi, Mohammadamin; Bin Adnan, Azlan; Sam, Abdul Rahman Bin Mohd; Tahir, Mahmood Md; Faridmehr, Iman; Hodjati, Reza

    2014-01-01

    The seismic performance of RC columns could be significantly improved by continuous spiral reinforcement as a result of its adequate ductility and energy dissipation capacity. Due to post-earthquake brittle failure observations in beam-column connections, the seismic behaviour of such connections could greatly be improved by simultaneous application of this method in both beams and columns. In this study, a new proposed detail for beam to column connection introduced as "twisted opposing rectangular spiral" was experimentally and numerically investigated and its seismic performance was compared against normal rectangular spiral and conventional shear reinforcement systems. In this study, three full scale beam to column connections were first designed in conformance with Eurocode (EC2-04) for low ductility class connections and then tested by quasistatic cyclic loading recommended by ACI Building Code (ACI 318-02). Next, the experimental results were validated by numerical methods. Finally, the results revealed that the new proposed connection could improve the ultimate lateral resistance, ductility, and energy dissipation capacity. PMID:25309957

  5. Tests on ferritic stainless steel simply supported and continuous SHS and RHS beams

    OpenAIRE

    Arrayago Luquin, Itsaso; Real Saladrigas, Esther; Mirambell Arrizabalaga, Enrique

    2015-01-01

    Development of efficient design guidance for stainless steel structures is key for the spreading of this corrosion-resistant material by considering both nonlinear behavior and strain hardening into predicting expressions, together with allowing the consideration of moment redistribution in indeterminate structures. With the aim of analyzing the bending moment redistribution capacity in ferritic stainless steel beams (RHS and SHS), an experimental programme is presented. The tests contribute ...

  6. Niobium thermal - mechanical treatment produced by continuously cast ingots and electron beam fusion

    International Nuclear Information System (INIS)

    Continuonsly cast Nb ingots produced in Brazil by electron beam fusion have been thermally-mechanically processed. These ingots were subjected to a pre-deformation between 0 to 50%, and subsequently treated thermally between 900 to 18000C for 2,3 and 4 hours. Grain refinement was attained by further reduction in area deformations between 42 to 96%, followed by thermal treatments for 3 hours between 810 to 13000C. The results material exhibited an equiaxial grain structure of 50 μm and was tensile tested. These tensile results are compared to the results for niobium produced by traditional commercial practices. (Author)

  7. An electrostatic glass actuator for ultrahigh vacuum: A rotating light trap for continuous beams of laser-cooled atoms.

    Science.gov (United States)

    Füzesi, F; Jornod, A; Thomann, P; Plimmer, M D; Dudle, G; Moser, R; Sache, L; Bleuler, H

    2007-10-01

    This article describes the design, characterization, and performance of an electrostatic glass actuator adapted to an ultrahigh vacuum environment (10(-8) mbar). The three-phase rotary motor is used to drive a turbine that acts as a velocity-selective light trap for a slow continuous beam of laser-cooled atoms. This simple, compact, and nonmagnetic device should find applications in the realm of time and frequency metrology, as well as in other areas of atomic, molecular physics and elsewhere. PMID:17979408

  8. SINQ - a continuous spallation neutron source (an approach to 1 MWatt of beam power)

    International Nuclear Information System (INIS)

    In this status report we describe the continuous spallation source at PSI, which will come into operation in fall 1996. We present the present state of the construction work and review the expected performance of the source. (author) 10 figs., 2 tabs., refs

  9. Design of CEBAF's [Continuous Electron Beam Accelerator Facility] rf separator and results of cold tests

    International Nuclear Information System (INIS)

    The design of the CEBAF accelerator system is based upon a multipass racetrack configuration, the straight sections of which will utilize 1497-MHz superconducting linac sections with independent magnetic transport at the end of each linac segment. Room temperature SW rf separators operating at a frequency of 998 MHz will be used in each independent transport channel at one end of the racetrack to extract a portion of the recirculating current. With the frequency chosen and appropriate phasing, three independent beams of correlated energy may be extracted for use in the three experimental areas. The design of the rf separators, abased on an alternating periodic structure (APS), will be described and some preliminary prototype cold test results will be given. 11 refs., 10 figs., 2 tabs

  10. Welding characteristics of austenitic 304 stainless steel using a continuous wave Nd:YAG laser beam

    International Nuclear Information System (INIS)

    Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much faster than those involved in conventional welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameter such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar and plates, etc. The follow conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone

  11. Direct Coupling of Electron Beam Irradiation and Polymer Extrusion for a Continuous Polymer Modification in Molten State

    International Nuclear Information System (INIS)

    The new approach of an e-beam initiating of chemical reactions in polymers in molten state results in some innovative results. High temperature, intensive macromolecular mobility and the absence of any crystallinity are some reasons for achieving unexpected structures, processing behaviour and properties changes in such treated thermoplastics and rubbers. Examples are a much more effective crosslinking of polyethylene and special rubbers, long chain branching of polypropylene or a partial crosslinking of polysulfone. Additionally, most of these modification effects are also achievable by a direct coupling of electron beam irradiation and conventional polymer extrusion processing for a continuous polymer modification in molten state. For realizing this unique processing technique a special MOBILE RADIATION FACILITY (MOBRAD1/T) was designed, constructed and manufactured in the IPF Dresden at which a lab-scale single screw extruder was adapted direct to an electron beam accelerator to realize a prompt irradiation of extruded polymer melt profiles before there solidification. Surprisingly, as a result of these short-time-melt reactions some effective and new polymer modification effects were found and will be presented

  12. The effect of switching cracks on the vibration of a continuous beam bridge subjected to moving vehicles

    Science.gov (United States)

    Fu, Chunyu

    2015-03-01

    During the service life of bridges, cracks can easily occur due to the dynamic loadings acting on them. These cracks may seriously affect the safety and serviceability of the bridges. Thus, this paper investigates the effect of these cracks on the vibration of a continuous beam bridge subjected to moving vehicles. The cracks are simulated by switching cracks, which can open and close fully instantaneously, and the beam behavior is considered as a sequence of linear states, each of which can be evaluated through a modal analysis. Special attention is paid to the analysis of the instant of crack switching, the linkage point of two adjacent linear states. The mode shapes and equation of motion corresponding to the new state after the switching are determined first. Next, the responses at the switching instant are recalculated. Finally, the beam displacement can be obtained by taking these responses as the initial condition. A numerical method is applied to investigate the validity of the proposed method, and the results show that the crack switching can result in higher accelerations, alter the slopes of the modal contributions to the displacement, and produce a new peak in the displacement history. During the resonance caused by a series of vehicles, the switching can reduce the first modal contribution to the resonance, but increase the second modal contribution. As a result, the resonant amplitude becomes smaller and the resonant mode changes.

  13. Emittance growth due to radial density variations of an emittance-dominated electron beam in a channel with continuous acceleration and focusing

    International Nuclear Information System (INIS)

    Simulations have identified charge-density variations as driving the dominant emittance growth mechanism for high-current, low-emittance induction linacs using solenoidal focusing, once the beam enters the emittance-dominated regime. In this paper, we use the radial equation of motion, including the nonlinearities resulting from radial density variations, to understand this effect. Nonlinearities in the beam close-quote s radial motion while in a solenoid arise from the noncancellation of the effects from the diamagnetic axial magnetic field and the potential depression of the beam, if the beam density is nonuniform. Any initial density variation drives a logarithmic increase in additional higher-order density variations (through the differential betatron motion), and an emittance growth that scales logarithmically, or greater (even potentially faster than linear), with the axial distance along the accelerator. The growth rate depends on the beam current, the focusing force, and the accelerating gradient, and for typical machine parameters, the growth rate can be faster than linear with distance. The magnitude of the emittance growth depends critically on the matching of the beam from the injector to the beamline. This formalism leads to a criterion of how uniform the beam density has to be and how well the beam needs to be matched in order not to have an unacceptable emittance growth. copyright 1998 American Institute of Physics

  14. CEBAF [Continuous Electron Beam Accelerator Facility] superconducting cavity rf drive system

    International Nuclear Information System (INIS)

    The CEBAF rf system consists of 418 individual rf amplifier chains. Each superconducting cavity is phase locked to the master drive reference line to within 1 degree, and the cavity field gradient is regulated to within 1 part in 104 by a state-of-the-art rf control module. Precision, continuously adjustable, modulo 3600 phase shifters are used to generate the individual phase references, and a compensated rf detector is used for level feedback. The close coupled digital system enhances system accuracy, provides self-calibration, and continuously checks the system for malfunction. Calibration curves, the operating program, and system history are stored in an on board EEPROM. The rf power is generated by a 5kW, water cooled, permanent magnet focused klystron. The klystrons are clustered in groups of 8 and powered from a common supply. rf power is transmitted to the accelerator sections by semiflexible waveguide

  15. Workshop on CEBAF [Continuous Electron Beam Accelerator Facility] spectrometer magnet design and technology: Proceedings

    International Nuclear Information System (INIS)

    The planned experimental program at CEBAF includes high-resolution, large acceptance spectrometers and a large toroidal magnetic, detector. In order to take full advantage of the high quality beam characteristics, the performances required will make these devices quite unique instruments compared to existing facilities in the same energy range. Preliminary designs have shown that such performances can be reached, but key questions concerning design concepts and most appropriate and cost-effective technologies had to be answered before going further with the designs. It was the purpose of the Workshop on CEBAF Spectrometer Magnet Design and Technology, organized by the CEBAF Research and Engineering Divisions, to provide the most complete information about the state-of-the-art tools and techniques in magnet design and construction and to discuss the ones most appropriate to the CEBAF spectrometers. In addition, it is expected that this Workshop will be the staring point for further interactions and collaborations between international magnet experts and the CEBAF staff, during the whole process of designing and building the spectrometers

  16. High-power continuous-wave tunable 544- and 272-nm beams based on a diode-oscillator fiber-amplifier for calcium spectroscopy

    Science.gov (United States)

    Ko, Kwang-Hoon; Kim, Yonghee; Park, Hyunmin; Cha, Yong-Ho; Kim, Taek-Soo; Lee, Lim; Lim, Gwon; Han, Jaemin; Ko, Kwang-Hee; Jeong, Do-Young

    2015-08-01

    Continuous-wave single-frequency tunable 544- and 272-nm beams have been demonstrated by the second- and fourth-harmonic conversions of a 1088-nm fundamental beam from a diode-oscillator fiber-amplifier. The single-pass second-harmonic generation with a MgO-doped periodically poled stoichiometric LiTaO3 crystal and the external-cavity frequency-doubling technique with a bulk BBO crystal were employed to achieve an approximately 6-W 544-nm beam and a 1.5-W 272-nm beam, respectively. We characterized the second- and fourth-harmonic generations and discussed their applications to calcium spectroscopy.

  17. Amplification of ultrashort electromagnetic pulses propagating along quasi-continuous electron beams

    Science.gov (United States)

    Baryshev, V. R.; Ginzburg, N. S.; Zotova, I. V.; Sergeev, A. S.; Rozental, R. M.; Yalandin, M. I.

    2009-01-01

    Specific features of amplification of short electromagnetic pulses propagating along steady-state nonequilibrium electron flows with a group velocity differing from the translational velocity of particles are analyzed. It is shown that an amplitude level substantially higher than the saturation level in amplification of quasi-continuous signals can be attained by permanent injection of electrons without initial modulation to one of the pulse fronts. The effective duration of the pulse being amplified is reduced simultaneously. The Cherenkov and undulator interaction mechanisms are considered. Analysis is carried out using a simple 1D model based on the averaged description of the electron-wave interaction, as well as direct numerical simulation based on the KARAT code taking into account the parameters of planned experiments on observation of this effect.

  18. Computation of ion implantation uniformity

    International Nuclear Information System (INIS)

    Commercial ion implanters employ a variety of different systems to scan the ion beam over the target. In many of the target scanning systems employed the achievable uniformity of dose has been limited by the chosen geometry. This paper describes a computer program which has been used to calculate the dose uniformity of a number of these systems. The results are presented as iso-dose lines relative to the dose at the centre of the target. The non-uniformities are then directly apparent and the parameters controlling their magnitude can be readily considered by equipment designers, purchasers or users. (author)

  19. z一致连续的倒向随机微分方程解的一个存在唯一性结果%An Existence and Uniqueness Result for BSDEs with Uniformly Continuous Generators in z

    Institute of Scientific and Technical Information of China (English)

    范胜君; 江龙

    2011-01-01

    This paper establishes an existence and uniqueness result for the solution to a one-dimensional backward stochastic differential equation (BSDE for short) whose generator satisfies Constantin's condition in y and is uniformly continuous in z, which generalizes some known results.%建立了关于一维倒向随机微分方程(简写为BSDE)的一个存在唯一性结果,其中BSDE的生成元g关于y满足Constantin条件,关于z是一致连续的.这改进了一些已知结果.

  20. Nonlinear dynamics and chaotization of oscillations of a virtual cathode in an annular electron beam in a uniform external magnetic field

    Science.gov (United States)

    Kurkin, S. A.; Koronovski, A. A.; Hramov, A. E.

    2009-08-01

    Results are presented from a numerical study of the effect of an external magnetic field on the conditions and mechanisms for the formation of a virtual cathode in a relativistic electron beam. Characteristic features of the nonlinear dynamics of an electron beam with a virtual cathode are considered when the external magnetic field is varied. Various mechanisms are investigated by which the virtual cathode oscillations become chaotic and their spectrum becomes a multifrequency spectrum, thereby complicating the dynamics of the vircator system. A general mechanism for chaotization of the oscillations of a virtual cathode in a vircator system is revealed: the electron structures that form in an electron beam interact by means of a common space charge field to give rise to additional internal feedback. That the oscillations of a virtual cathode change from the chaotic to the periodic regime is due to the suppression of the mechanism for forming secondary electron structures.

  1. Optimization of GATE and PHITS Monte Carlo code parameters for uniform scanning proton beam based on simulation with FLUKA general-purpose code

    Energy Technology Data Exchange (ETDEWEB)

    Kurosu, Keita [Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871 (Japan); Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871 (Japan); Takashina, Masaaki; Koizumi, Masahiko [Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871 (Japan); Das, Indra J. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN 46202 (United States); Moskvin, Vadim P., E-mail: vadim.p.moskvin@gmail.com [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN 46202 (United States)

    2014-10-01

    Although three general-purpose Monte Carlo (MC) simulation tools: Geant4, FLUKA and PHITS have been used extensively, differences in calculation results have been reported. The major causes are the implementation of the physical model, preset value of the ionization potential or definition of the maximum step size. In order to achieve artifact free MC simulation, an optimized parameters list for each simulation system is required. Several authors have already proposed the optimized lists, but those studies were performed with a simple system such as only a water phantom. Since particle beams have a transport, interaction and electromagnetic processes during beam delivery, establishment of an optimized parameters-list for whole beam delivery system is therefore of major importance. The purpose of this study was to determine the optimized parameters list for GATE and PHITS using proton treatment nozzle computational model. The simulation was performed with the broad scanning proton beam. The influences of the customizing parameters on the percentage depth dose (PDD) profile and the proton range were investigated by comparison with the result of FLUKA, and then the optimal parameters were determined. The PDD profile and the proton range obtained from our optimized parameters list showed different characteristics from the results obtained with simple system. This led to the conclusion that the physical model, particle transport mechanics and different geometry-based descriptions need accurate customization in planning computational experiments for artifact-free MC simulation.

  2. Optimization of GATE and PHITS Monte Carlo code parameters for uniform scanning proton beam based on simulation with FLUKA general-purpose code

    International Nuclear Information System (INIS)

    Although three general-purpose Monte Carlo (MC) simulation tools: Geant4, FLUKA and PHITS have been used extensively, differences in calculation results have been reported. The major causes are the implementation of the physical model, preset value of the ionization potential or definition of the maximum step size. In order to achieve artifact free MC simulation, an optimized parameters list for each simulation system is required. Several authors have already proposed the optimized lists, but those studies were performed with a simple system such as only a water phantom. Since particle beams have a transport, interaction and electromagnetic processes during beam delivery, establishment of an optimized parameters-list for whole beam delivery system is therefore of major importance. The purpose of this study was to determine the optimized parameters list for GATE and PHITS using proton treatment nozzle computational model. The simulation was performed with the broad scanning proton beam. The influences of the customizing parameters on the percentage depth dose (PDD) profile and the proton range were investigated by comparison with the result of FLUKA, and then the optimal parameters were determined. The PDD profile and the proton range obtained from our optimized parameters list showed different characteristics from the results obtained with simple system. This led to the conclusion that the physical model, particle transport mechanics and different geometry-based descriptions need accurate customization in planning computational experiments for artifact-free MC simulation

  3. Research And Design Of A Shielding System For Improving Dose Uniformity Ratio (DUR) And Setting Up A Set Of Operational Instruction For Running The Electron Beam Accelerator UELR-10-15S2

    International Nuclear Information System (INIS)

    The project “Research and design of a shielding system for improving dose uniformity ratio and setting up a set of operational instruction for the electron beam accelerator UELR-10-15S2 at Research and Development Center for Radiation Technology - VINAGAMMA” has been set up and implemented to improve dose uniformity ratio (DUR) for products with the areal densities in the range of 4.5 - 7.0 g/cm2 in the irradiation by electron beam of 10 MeV energy and to set up the first set of operational instruction of the accelerator UELR-10-15S2. By using the shielding system with the areal densities of 1.5 g/cm2 and 2.5 g/cm2, the DUR values for products with the above range are reduced lower than 2 for food irradiation and the utilization of the accelerator has been significantly enhanced. The set of operational instruction of the accelerator UELR-10-15S2 has been set up and approved by the center director in order to put it in force. (author)

  4. Analysis of methods for obtaining of a uniform particle distribution on a target on its irradiation by a beam of the krypton ions extracted from the implantator IC-100

    CERN Document Server

    Gikal, B N; Kazarinov, N

    2002-01-01

    Some methods of the target uniform irradiation by heavy ions have been analyzed. As a result the scanning system for the sup 8 sup 4 Kr sup 1 sup 5 sup + ion beam extracted from the cyclotron IC-100 has been chosen and worked up. It consists of two deflecting yokes creating horizontal and vertical magnetic fields. The yokes are supplied by generators of saw-tooth current having the definitely fixed frequencies. When both generators work synchronously the centre of mass of the ion beam 'draws' a pattern on the target. The dimensions of the pattern cells are determined by the ratio of these frequencies. The correlation between the generator frequencies when heterogeneity of the particle density distribution does not exceed the required value of +- 5% is obtained. It has been shown that for the moving target the chosen scanning scheme allows one to obtain its uniform density distribution. For the slow target velocities (20-50 cm/s) this scheme also allows one to compensate the collapse in the particle density di...

  5. A low-cost, accurate and non-intercepting continuous method for beam current measurements in a high-current ion implanter

    International Nuclear Information System (INIS)

    The development of a low-cost, accurate, non-intercepting continuous method for measuring the beam current in a high-current ion implanter is described. The method, named a differential current monitor, is based on the electric charge conservation principle, applied to the currents that flow in the implanter electrical system, due to the acceleration voltage applied to the ion beam and the leakage currents to ground. This method allows for continuous measurement of the ion beam current without intercepting it. Since its installation, it is possible to accurate measure ion beam currents from tens of μA to mA, which is the normal range for this type of system

  6. On uniform topological algebras

    OpenAIRE

    Azhari, M. El

    2013-01-01

    The uniform norm on a uniform normed Q-algebra is the only uniform Q-algebra norm on it. The uniform norm on a regular uniform normed Q-algebra with unit is the only uniform norm on it. Let A be a uniform topological algebra whose spectrum M (A) is equicontinuous, then A is a uniform normed algebra. Let A be a regular semisimple commutative Banach algebra, then every algebra norm on A is a Q-algebra norm on A.

  7. A coupled analysis of fluid flow, heat transfer and deformation behavior of solidifying shell in continuously cast beam blank

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung Eui; Yeo, Tae Jung; Oh, Kyu Hwan; Yoon, Jong Kyu [School of Materials Science and Engineering, Seoul Nat`l Univ., Seoul (Korea, Republic of); Han, Heung Nam [Oxford Center for Advanced Materials and Composites, Department of Materials, Univ. of Oxford (United Kingdom)

    1997-12-31

    A mathematical model for a coupled analysis of fluid flow, heat transfer and deformation behavior in the continuously cast beam blank has been developed. The fluid flow, heat transfer and solidification in the mold region were analyzed with 3-dimensional finite difference method (FDM) based on control volume method. A body fitted coordinate system was introduced for the complex geometry of the beam blank. The effects of turbulence and natural convection of molten steel were taken into account in determining the fluid flow in the strand. The thermo-elasto-plastic deformation behavior in the cast strand and the formation of air gap between the solidifying shell and the mold were analyzed by the finite element method (FEM) using the 2-dimensional slice temperature profile calculated by the FDM. The heat flow between the strand and the mold was evaluated by the coupled analysis between the fluid flow-heat transfer analysis and the thermo-elasto-plastic stress analysis. In order to determine the solid fraction in the mushy zone, the microsegregation of solute element was assessed. The effects of fluid flow on the heat transfer, the solidification of steel and the distribution of shell thickness during the casting of the beam blank were simulated. The deformation behavior of the solidifying shell and the possibility of cracking of the strand were also investigated. The recirculating flows were developed in the regions of the web and the flange tip. The impinging of the inlet flow from the nozzle retarded the growing of solidifying shell in the regions of the fillet and the flange. The air gap between the strand and the mold was formed near the region of the corner of the flange tip. At the initial stage of casting, the probability of the surface cracking was high in the regions of the fillet and the flange tip. After the middle stage of casting, the internal cracking was predicted in the regions of the flange tip, and between the fillet and the flange tip. (author) 38

  8. Measurement and analysis of internal loss and injection efficiency for continuous-wave blue semipolar ( 20 2 ¯ 1 ¯ ) III-nitride laser diodes with chemically assisted ion beam etched facets

    Science.gov (United States)

    Becerra, Daniel L.; Kuritzky, Leah Y.; Nedy, Joseph; Saud Abbas, Arwa; Pourhashemi, Arash; Farrell, Robert M.; Cohen, Daniel A.; DenBaars, Steven P.; Speck, James S.; Nakamura, Shuji

    2016-02-01

    Continuous-wave blue semipolar ( 20 2 ¯ 1 ¯ ) III-nitride laser diodes were fabricated with highly vertical, smooth, and uniform mirror facets produced by chemically assisted ion beam etching. Uniform mirror facets are a requirement for accurate experimental determination of internal laser parameters, including internal loss and injection efficiency, which were determined to be 9 cm-1 and 73%, respectively, using the cavity length dependent method. The cavity length of the uncoated devices was varied from 900 μm to 1800 μm, with threshold current densities ranging from 3 kA/cm2 to 9 kA/cm2 and threshold voltages ranging from 5.5 V to 7 V. The experimentally determined internal loss was found to be in good agreement with a calculated value of 9.5 cm-1 using a 1D mode solver. The loss in each layer was calculated and in light of the analysis several modifications to the laser design are proposed.

  9. Ion-recombination correction factor {kappa}{sub sat} for spherical ion chambers irradiated by continuous photom beams

    Energy Technology Data Exchange (ETDEWEB)

    Piermattei, A.; Azario, L.; Arcovito, G. [Universita Cattolica S Cuore. Rome (Italy). Ist. di Fisica; Toni, M.P. [Ente Nazionale per l`Energia Elettrica, Rome (Italy)

    1996-06-01

    The large range of reference air kerma rates of brachytherapy sources involves the use of large-volume ionization chambers. When such ionization chambers are used the ion-recombination correction factor k{sub sat} has to be determined. In this paper three spherical ion chambers with volume ranging from 30 to 10{sup 4} cm{sup 3} have been irradiated by photons of a {sup 192}Ir source to determine the k{sub sat} factors. The ionization currents of the ion chambers as a function of the applied voltage and the air kerma rate have been analysed to determine the contribution of the initial and general ion recombination. The k{sub sat} values for large-volume ionization chambers obtained by considering the general ion recombination as predominant (Almond`s approach) are in disagreement with the results obtained using methods that consider both initial and general ion-recombination contributions (Niatel`s approach). Such disagreement can reach 0.7% when high currents are measured for a high-activity source calibration in terms of reference air kerma rate. In this study a new `two-voltage` method, independent of the voltage ratio given by a dosimetry system, is proposed for practical dosimetry of continuous x-and gamma-radiation beams. In the case where the Almond approach is utilized, the voltage ratio V{sub 1}/V{sub 2} should be less than 2 instead of Almond`s limit of V{sub 1}/V{sub 2} <5. (Author).

  10. Uniformity of fuel target implosion in Heavy Ion Fusion

    OpenAIRE

    Kawata, S; Noguchi, K.; Suzuki, T; Karino, T.; Barada, D.; Ogoyski, A. I.; Ma, Y. Y.

    2014-01-01

    In inertial confinement fusion the target implosion non-uniformity is introduced by a driver beams' illumination non-uniformity, a fuel target alignment error in a fusion reactor, the target fabrication defect, et al. For a steady operation of a fusion power plant the target implosion should be robust against the implosion non-uniformities. In this paper the requirement for the implosion uniformity is first discussed. The implosion uniformity should be less than a few percent. A study on the ...

  11. Enhanced temperature uniformity by tetrahedral laser heating

    OpenAIRE

    Schroers, Jan; Bossuyt, Sven; Rhim, Won-Kyu; Li, Jianzhong; Zhou, Zhenhua; Johnson, William L.

    2004-01-01

    emperature profile on a spherical sample that is heated by laser beams in various geometries while processed in vacuum is analyzed. Sample heating by one or four laser beams was considered. An analytical expression was derived for directional sample heating cases. It suggests an enhanced temperature uniformity over the samples when heated with four diffuse laser beams arranged in a tetrahedral geometry. This was experimentally verified by heating a spherical stainless steel sample by laser be...

  12. Solution for non-uniform of crystal product size with continuous process by TRIZ%运用TRIZ解决连续法生产中结晶产品粒度不均匀问题

    Institute of Scientific and Technical Information of China (English)

    杨建中

    2012-01-01

    The theory and solution for inventive problems--TRIZ is briefly introduced including the core theory, two kinds of methods for analyzing the technical problems and five kinds of tools for solving the technical problems. The non-uniform of crystal product size with continuous process is analyzed and studied with the physical contradiction method and technical contradiction method of TRIZ, the solutions for problems are put forward.%对技术发明理论和方法体系——TRIZ作了简要介绍,阐述了TRIZ的核心理论、TRIZ分析技术问题的2种方法和TRIZ解决技术问题的5种工具。针对连续法生产中普遍存在的结晶产品颗粒不均匀问题,运用TRIZ中的物理矛盾法和技术矛盾法进行了分析研究,提出了解决问题的方法。

  13. Local zone wise elastic and plastic properties of electron beam welded Ti-6Al-4V alloy using digital image correlation technique: A comparative study between uniform stress and virtual fields method

    Science.gov (United States)

    Saranath, K. M.; Ramji, M.

    2015-05-01

    Joining of materials using welding results in the formation of material zones with varying microstructure across the weld. Extraction of the mechanical properties of those individual heterogeneous zones are important in designing components and structures comprised of welds. In this study, the zone wise local extraction of the elastic and plastic properties of an electron beam welded Ti-6Al-4V titanium alloy has been carried out using both the uniform stress method (USM) and the virtual fields method (VFM) involving digital image correlation (DIC) technique. The surface strain field obtained using DIC technique from a transverse weld specimen tensile testing is used for extracting the zone wise strain evolution. Initially, using uniform stress assumption, zone wise full range stress-strain curves are extracted. In USM methodology, the elastic and plastic material models are fitted to the zone wise stress-strain curves and required parameters are extracted from it. But inherent disadvantage is lot of images need to be processed for the parameter extraction. Recently, VFM is gaining lot of popularity in characterization domain as it is robust, accurate and faster. VFM is based on the principle of virtual work where, the weak form of local equilibrium equations and kinematically admissible virtual displacement fields are utilized for parameter extraction. Hollomon's power law is used here as the hardening rule. Young's modulus, Poisson's ratio, yield stress, strength coefficient and strain hardening exponent are the parameters extracted zone wise using both USM and VFM. A Vicker's microhardness measurement is also conducted across the weld zone towards mapping the strength behavior. Fusion zone has reported higher yield strength, strength coefficient and Poisson's ratio. Young's modulus value is found decreasing from base metal towards the fusion zone. The trend observed in parameter variation across the weld zone obtained by both USM and VFM compares very well. Due

  14. Start-up of beam emittance shaping line of the NIIYaF MGU continuous action racetrack microtron

    International Nuclear Information System (INIS)

    Results of start-up of longitudinal and transverse emittance shaping line for 100 keV and up to 10 mA electron beam of aracetrack microtron are presented. The shaping line includes electron gun, magnetic lenses, correctors, vacuum seal, profile monitor. The line permit to obtain 10-15 deg of bunching. 6 refs.; 3 figs

  15. Do School Uniforms Fit?

    Science.gov (United States)

    White, Kerry A.

    2000-01-01

    In 1994, Long Beach (California) Unified School District began requiring uniforms in all elementary and middle schools. Now, half of all urban school systems and many suburban schools have uniform policies. Research on uniforms' effectiveness is mixed. Tightened dress codes may be just as effective and less litigious. (MLH)

  16. School Uniforms Redux.

    Science.gov (United States)

    Dowling-Sendor, Benjamin

    2002-01-01

    Reviews a recent decision in "Littlefield" by the 5th Circuit upholding a school uniform policy. Advises board member who wish to adopt a school uniform policy to solicit input from parents and students, research the experiences of other school districts with uniform policies, and articulate the interests they wish to promote through uniform…

  17. Mandatory School Uniforms.

    Science.gov (United States)

    Cohn, Carl A.

    1996-01-01

    Shortly after implementing a mandatory school uniform policy, the Long Beach (California) Public Schools can boast 99% compliance and a substantial reduction in school crime. The uniforms can't be confused with gang colors, save parents money, and help identify outsiders. A sidebar lists ingredients for a mandatory uniform policy. (MLH)

  18. Analysis of nonlinear dynamics of a cantilever beam-rigid-body MEMS gyroscope using a continuation method

    CERN Document Server

    Lajimi, Seyed Amir Mousavi

    2014-01-01

    The nonlinear dynamics of a microbeam-rigid body gyroscope are investigated by using a continuation method. To study the nonlinear dynamics of the system, the Lagrangian of the system is discretized and the reduced-order model is obtained. By using the continuation method, the frequency-response curves are computed and the stability of response is determined.

  19. EFFECT OF SUBMERGED ENTRY NOZZLE (SEN) PARAMETERS AND SHAPE ON 3-D FLUID FLOW IN MOULD FOR BEAM BLANK CONTINUOUS CASTING

    Institute of Scientific and Technical Information of China (English)

    Y.P.Du; J.W.Yang; R.Shi; X.C.Cui

    2004-01-01

    According to turbulent theory and characteristics of beam blank continuous casting, 3-Dmodel to represent the flow of beam blank mould is established. The predicted results indicate that the exit obliquity of up 15°(+15°) should be adopted, which will benefit the floatation of non-metallic inclusion and purification of the molten steel. When the nozzle angle is 120°, the flow pattern is reasonable. Proper nozzle depth can be 200mm. Turbulent kinetic of meniscus can be reduced by adopting the square nozzle and suitable area of side outlet when casting speed increases. The results are consistent with those of water model experiment, so the model is exact and reasonable. The model can provide important information for design of SEN and defining of immersion depth.

  20. School Uniform Policies in Public Schools

    Science.gov (United States)

    Brunsma, David L.

    2006-01-01

    The movement for school uniforms in public schools continues to grow despite the author's research indicating little if any impact on student behavior, achievement, and self-esteem. The author examines the distribution of uniform policies by region and demographics, the impact of these policies on perceptions of school climate and safety, and…

  1. Comparison of step-and-shoot and continuous scanning methods in cone-beam computed micro-tomography for NDT

    International Nuclear Information System (INIS)

    The purpose of this study is to compare the quality of images obtained from the step-and-shoot and continuous scanning methods in terms of system resolution. In addition, this study aims to determine the fastest continuous scanning speed with image quality enough for the defect inspection. Computed tomography (CT) is an emerging technology for the non-destructive testing (NDT) of high precision manufacturing to enhance the production reliability. In order to use the CT for the NDT, high-speed inspection is essential for a higher production yield. However, conventional high resolution CT systems usually require terms of minutes to take exam because they employ the step-and-shoot protocol to avoid motion blur during the image acquisition. Unlike the step-and-shoot protocol, continuous scan protocol, which simultaneously acquires projection images during the rotation, can only require terms of seconds because it can ignore the time delay between 'stop and go' steps of rotation. Continuous scan is used for medical CT systems. However, the loss of system resolution originated from the motion blur cannot be avoidable. In order to investigate the relationship between acquisition time and image quality of continuous scanning, the experiment will be conducted with varying rotational speed of object

  2. Use of the TACL [Thaumaturgic Automated Control Logic] system at CEBAF [Continuous Electron Beam Accelerator Facility] for control of the Cryogenic Test Facility

    International Nuclear Information System (INIS)

    A logic-based control software system, called Thaumaturgic Automated Control Logic (TACL), is under development at the Continuous Electron Beam Accelerator Facility in Newport News, VA. The first version of the software was placed in service in November, 1987 for control of cryogenics during the first superconducting RF cavity tests at CEBAF. In August, 1988 the control system was installed at the Cryogenic Test Facility (CTF) at CEBAF. CTF generated liquid helium in September, 1988 and is now in full operation for the current round of cavity tests. TACL is providing a powerful and flexible controls environment for the operation of CTF. 3 refs

  3. Continuously-tunable microwave photonic true-time-delay based on a fiber-coupled beam deflector and diffraction grating.

    Science.gov (United States)

    Schermer, Ross T; Bucholtz, Frank; Villarruel, Carl A

    2011-03-14

    This paper reports the demonstration of a continuously-tunable true-time delay line for microwave photonics and optical communications capable of high-resolution phase control throughout the 1-100 GHz modulation range. A fiber-coupled device is demonstrated with 75 ps of continuous delay tuning range, 3 dB optical insertion loss, and minimal RF amplitude and phase variation over the 4-18 GHz band. Measured delay ripple was less than 0.2 ps. Theoretical analysis is also presented which indicates scalability to delay tuning ranges over 1000 ps and modulation bandwidths over 10 THz. PMID:21445175

  4. A continuous wave millimeter free electron laser experiment with a Cockcroft-Walton accelerator and electron beam recovery

    International Nuclear Information System (INIS)

    Problems relevant to a continuous wave free electron laser (FEL) in the centimeter-millimeter region are investigated. The ideas are applied to the FEL experiment in progress at the Legnaro (Padova) INFN laboratory. The accelerator characteristics and laser parameters are discussed. The laser could sweep the centimeter-millimeter region until 2.5 mm with a power around 15 kW

  5. Butt welding characteristics of austenitic 304 stainless steel using a continuous wave Nd:YAG laser beam

    International Nuclear Information System (INIS)

    Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much faster than those involved in conventional arc welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameters such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar plates, etc. The following conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/ aspect ratio and hence a decease in the fusion zone size. The penetration depth increased with the increase in laser power

  6. A method to compensate the energy loss of a continuous stacked beam with a large momentum spread

    International Nuclear Information System (INIS)

    A system of rectangular drift tube loaded cavities resonating in the TE 101 mode combined with a cyclic scaling guide field can be used to accelerate an unbunched beam of charged particles. The system is superior to phase displacement because the cavities are driven at a fixed frequency with certain phase differences between each other. The range of particle momenta is limited by rf-knock out. Rf-induced betatron oscillations and phase dependent momentum changes can be compensated by means of sixteen cavities on the circumference of the accelerator. The amplitude of the betatron oscillations and the energy gain were calculated numerically for storage devices consisting of a spiral-sector FFAG guide field and one or sixteen cavities, respectively, using measured rf-feld data. The systems seem to be practical only for electrons with an energy up to 100 MeV. The rf-system works within an energy width of several MeV. (Auth.)

  7. Use of MV and kV imager correlation for maintaining continuous real-time 3D internal marker tracking during beam interruptions

    Science.gov (United States)

    Wiersma, R. D.; Riaz, N.; Dieterich, Sonja; Suh, Yelin; Xing, L.

    2009-01-01

    The integration of onboard kV imaging together with a MV electronic portal imaging device (EPID) on linear accelerators (LINAC) can provide an easy to implement real-time 3D organ position monitoring solution for treatment delivery. Currently, real-time MV-kV tracking has only been demonstrated by simultaneous imagining by both MV and kV imaging devices. However, modalities such as step-and-shoot IMRT (SS-IMRT), which inherently contain MV beam interruptions, can lead to loss of target information necessary for 3D localization. Additionally, continuous kV imaging throughout the treatment delivery can lead to high levels of imaging dose to the patient. This work demonstrates for the first time how full 3D target tracking can be maintained even in the presence of such beam interruption, or MV/kV beam interleave, by use of a relatively simple correlation model together with MV-kV tracking. A moving correlation model was constructed using both present and prior positions of the marker in the available MV or kV image to compute the position of the marker on the interrupted imager. A commercially available radiotherapy system, equipped with both MV and kV imaging devices, was used to deliver typical SS-IMRT lung treatment plans to a 4D phantom containing internally embedded metallic markers. To simulate actual lung tumor motion, previous recorded 4D lung patient motion data were used. Lung tumor motion data of five separate patients were inputted into the 4D phantom, and typical SS-IMRT lung plans were delivered to simulate actual clinical deliveries. Application of the correlation model to SS-IMRT lung treatment deliveries was found to be an effective solution for maintaining continuous 3D tracking during 'step' beam interruptions. For deliveries involving five or more gantry angles with 50 or more fields per plan, the positional errors were found to have <=1 mm root mean squared error (RMSE) in all three spatial directions. In addition to increasing the robustness of

  8. School Uniforms. Research Brief

    Science.gov (United States)

    Walker, Karen

    2007-01-01

    Does clothing make the person or does the person make the clothing? How does what attire a student wears to school affect their academic achievement? In 1996, President Clinton cited examples of school violence and discipline issues that might have been avoided had the students been wearing uniforms ("School uniforms: Prevention or suppression?").…

  9. Games Uniforms Unveiled

    Institute of Scientific and Technical Information of China (English)

    Linda

    2008-01-01

    The uniforms for Beijing Olympics’ workers, technical staff and volunteers have been unveiled to mark the 200-day countdown to the Games. The uniforms feature the key element of the clouds of promise and will be in three colors:red for Beijing Olympic Games Committee staff, blue

  10. Change in operating parameters of the Continuous Electron Beam Accelerator Facility and Free Electron Laser, Thomas Jefferson National Accelerator Facility, Newport News, Virginia

    International Nuclear Information System (INIS)

    In this environmental assessment (EA), the US Department of Energy (DOE) reports the results of an analysis of the potential environmental impacts from a proposed change in operating parameters of the Continuous Electron Beam Accelerator Facility (CEBAF), and operation of the Free Electron Laser (FEL) facility beyond the initial demonstration period. With this proposal, DOE intends to increase CEBAF operating range from its current operating maximum beam energy of 4.0 GeV [giga-(billion) electron volts] to 8.0 GeV at a beam power of no greater than 1,000 kW [1 megawatt (MW)], its maximum attainable level, based on current technology and knowledge, without significant, costly equipment modifications. DOE has prepared an EA for this action to determine the potential for adverse impacts from operation of CEBAF and the FEL at the proposed levels. Changing the operating parameters of CEBAF would require no new major construction and minor modifications to the accelerator, its support systems, the FEL, and onsite utility systems. Modifications and performance improvements would be made to (1) the accelerator housed in the underground tunnels, (2) its support systems located in the above ground service buildings, and (3) the water and equipment cooling systems both in the tunnel and at the ground surface. All work would be performed on previously disturbed land and in, on, or adjacent to existing buildings, structures, and equipment. With the proposed action, the recently constructed FEL facility at the Jefferson Lab would operate in concert with CEBAF beyond its demonstration period and up to its maximum effective electron beam power level of 210 kW. In this EA, DOE evaluates the impacts of the no-action alternative and the proposed action alternative. Alternatives considered, but dismissed from further evaluation, were the use of another accelerator facility and the use of another technology

  11. Uniformity of aluminium foils

    International Nuclear Information System (INIS)

    Commercially produced rolled and beaten Al foils and evaporated Al foils have been examined for thickness uniformity with an areal resolution of about 5 x 10-6 cm2 by measurements of proton backscattering yield using the Harwell microbeam facility. The evaporated Al foils were found to be uniform to better than 1% but the rolled foils were found to have non-uniformities of as much as 5-10% of their mean thickness. This is sufficient to contribute significantly to systematic errors in measurement of fast heavy ion energy straggling. (Auth.)

  12. Non-uniform reductions

    OpenAIRE

    Buhrman, H.; Hescott, B.; Homer, S.; Torenvliet, L.

    2010-01-01

    We study properties of non-uniform reductions and related completeness notions. We strengthen several results of Hitchcock and Pavan (ICALP (1), Lecture Notes in Computer Science, vol. 4051, pp. 465-476, Springer, 2006) and give a trade-off between the amount of advice needed for a reduction and its honesty on NEXP. We construct an oracle relative to which this trade-off is optimal. We show, in a more systematic study of non-uniform reductions, among other things that non-uniformity can be re...

  13. Non-uniform sampled scalar diffraction calculation using non-uniform fast Fourier transform

    OpenAIRE

    Shimobaba, Tomoyoshi; Kakue, Takashi; Oikawa, Minoru; Okada, Naohisa; Endo, Yutaka; Hirayama, Ryuji; Ito, Tomoyoshi

    2013-01-01

    Scalar diffraction calculations such as the angular spectrum method (ASM) and Fresnel diffraction, are widely used in the research fields of optics, X-rays, electron beams, and ultrasonics. It is possible to accelerate the calculation using fast Fourier transform (FFT); unfortunately, acceleration of the calculation of non-uniform sampled planes is limited due to the property of the FFT that imposes uniform sampling. In addition, it gives rise to wasteful sampling data if we calculate a plane...

  14. Continuation of full-scale three-dimensional numerical experiments on high-intensity particle and laser beam-matter interactions

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Warren, B.

    2012-12-01

    We present results from the grant entitled, Continuation of full-scale three-dimensional numerical experiments on high-intensity particle and laser beam-matter interactions. The research significantly advanced the understanding of basic high-energy density science (HEDS) on ultra intense laser and particle beam plasma interactions. This advancement in understanding was then used to to aid in the quest to make 1 GeV to 500 GeV plasma based accelerator stages. The work blended basic research with three-dimensions fully nonlinear and fully kinetic simulations including full-scale modeling of ongoing or planned experiments. The primary tool was three-dimensional particle-in-cell simulations. The simulations provided a test bed for theoretical ideas and models as well as a method to guide experiments. The research also included careful benchmarking of codes against experiment. High-fidelity full-scale modeling provided a means to extrapolate parameters into regimes that were not accessible to current or near term experiments, thereby allowing concepts to be tested with confidence before tens to hundreds of millions of dollars were spent building facilities. The research allowed the development of a hierarchy of PIC codes and diagnostics that is one of the most advanced in the world.

  15. High-performance poly-Si thin film transistors with highly biaxially oriented poly-Si thin films using double line beam continuous-wave laser lateral crystallization

    Science.gov (United States)

    Yamano, Masayuki; Kuroki, Shin-Ichiro; Sato, Tadashi; Kotani, Koji

    2014-01-01

    Highly biaxially oriented poly-Si thin films were formed by double-line beam continuous-wave laser lateral crystallization (DLB-CLC). The crystallinities of the DLB-CLC poly-Si thin films were (110), (111), and (211) for the laser scan, transverse, and surface directions, respectively, and an energetically stable Σ3 grain boundary was observed to be dominant. All silicon grains were elongated in the laser scan direction and one-dimensionally very large silicon grains with lengths of more than 100 µm were fabricated. Using these biaxially oriented polycrystalline silicon (poly-Si) films, low-temperature poly-Si TFTs (LTPS-TFTs) were fabricated at low temperatures (≦550 °C) by a metal gate self-aligned process. As a result, a TFT with a high electron field effect mobility of μFE = 450 cm2 V-1 s-1 in a linear region was realized.

  16. Continuous 7-Days-A-Week External Beam Irradiation in Locally Advanced Cervical Cancer: Final Results of the Phase I/II Study

    International Nuclear Information System (INIS)

    Purpose: To evaluate the feasibility and efficacy of definitive continuous 7-days-a-week pelvic irradiation without breaks between external beam radiotherapy and brachytherapy in locally advanced cervical cancer. Methods and Materials: Between November 1998 and December 1999, 30 patients with International Federation of Obstetrics and Gynecology Stage IIB or IIIB cervical cancer were included in a prospective Phase I/II study of continuous 7-days-a-week pelvic irradiation, to the total Manchester point B dose of 40.0–57.6 Gy. The first 13 patients (Group A) were given a daily tumor dose of 1.6 Gy, and the remaining 17 patients (Group B) were given 1.8 Gy. One or two immediate brachytherapy applications (point A dose 10–20 Gy, each) were performed in 28 cases. Results: Two patients did not complete the irradiation because of apparent early progression of disease during the irradiation. Eleven of the 28 evaluable patients (39%; 45% and 35% in Groups A and B, respectively) completed their treatment within the prescribed overall treatment time. Acute toxicity (including severe European Organisation for Research and Treatment of Cancer/Radiation Therapy Oncology Group Grade 3 and 4 effects in 40%) was experienced by 83% of patients and resulted in unplanned treatment interruptions in 40% of all patients (31% and 47% of patients in Groups A and B, respectively). Severe intestinal side effects occurred in 31% and 41% of Patients in Groups A and B, respectively (p = 0.71). The 5-year overall survival probability was 33%. Cancer recurrence occurred in 63% of patients: 20% inside and 57% outside the pelvis. Cumulative incidence of late severe bowel and urinary bladder toxicity at 24 months was 15%. Conclusion: Continuous irradiation in locally advanced cervical cancer is associated with a high incidence of severe acute toxicity, resulting in unplanned treatment interruptions. Late severe effects and survival after continuous radiotherapy do not substantially differ from

  17. Devaney's chaos on uniform limit maps

    International Nuclear Information System (INIS)

    Highlights: → The transitivity may not been inherited even if the sequence functions mixing. → The sensitivity may not been inherited even if the iterates of sequence have some uniform convergence. → Some equivalence conditions for the transitivity and sensitivity for uniform limit function are given. → A non-transitive sequence may converge uniformly to a transitive map. - Abstract: Let (X, d) be a compact metric space and fn : X → X a sequence of continuous maps such that (fn) converges uniformly to a map f. The purpose of this paper is to study the Devaney's chaos on the uniform limit f. On the one hand, we show that f is not necessarily transitive even if all fn mixing, and the sensitive dependence on initial conditions may not been inherited to f even if the iterates of the sequence have some uniform convergence, which correct two wrong claims in . On the other hand, we give some equivalence conditions for the uniform limit f to be transitive and to have sensitive dependence on initial conditions. Moreover, we present an example to show that a non-transitive sequence may converge uniformly to a transitive map.

  18. Length and quality of survival after external-beam radiotherapy with concurrent continuous 5-fluorouracil infusion for locally unresectable pancreatic cancer

    International Nuclear Information System (INIS)

    Purpose: The purpose of this study was to evaluate whether external-beam radiotherapy (EBRT) with concurrent continuous 5-fluorouracil (5-FU) infusion affects the length and quality of survival in patients with locally unresectable pancreatic cancer. Methods: Thirty-one patients with histologically proven locally advanced and unresectable pancreatic cancer without distant metastases were evaluated in this prospective randomized trial. Sixteen patients received EBRT (50.4 Gy/28 fractions) with concurrent continuous infusion of 5-FU (200 mg/m2/day), whereas 15 patients received no chemoradiation. The length and quality of survival was analyzed and compared for the two groups. Results: The median survival of 13.2 months and the 1-year survival rate of 53.3% in the chemoradiation group were significantly better than the respective 6.4 months and 0% in the group without chemoradiotherapy (p=0.0009). The average monthly Karnofsky score, a quality of life indicator, was 77.1 in the chemoradiation group, which was significantly higher than the 65.5 in the group without chemoradiotherapy (p<0.0001). The number of hospital days per month of survival was significantly less in the chemoradiation than in the no-therapy group (12.3 vs. 19.0 days, p<0.05). In the chemoradiation group, 5 patients (31%) had a partial response, and 9 (56%) had radiologically stable disease at a median duration of 6.1 months. The patients who had chemoradiation had a lower rate of liver and peritoneal metastases than patients without chemoradiotherapy (31% vs. 64%). Of 10 patients who experienced pain before chemoradiation, 8 (80%) received pain relief that lasted a median of 5.2 months. Conclusions: EBRT with concurrent continuous 5-FU infusion increased the length and quality of survival as compared to no chemoradiotherapy and provided a definite palliative benefit for patients with unresectable pancreatic cancer

  19. Space charge dominated beams

    International Nuclear Information System (INIS)

    After an introductory section on the relationship between emittance and beam Coulomb energy we discuss the properties of space charge dominated beams in progressive steps: from uniformly charged bunched beams to non-uniformly charged beams to correlation effects between particles (simulation beams or 'crystalline' beams). A practical application can be found in the beam dynamics of a high-current injector. The concept of correlation energy is of practical interest in computer simulation of high-brilliance beams, where one deals with an artificially enhanced two-particle Coulomb energy, if many real particles are combined into one simulation super-particle. This can be a source of non-physical emittance growth. (orig./HSI)

  20. High specific capacity retention of graphene/silicon nanosized sandwich structure fabricated by continuous electron beam evaporation as anode for lithium-ion batteries

    International Nuclear Information System (INIS)

    Highlights: • A graphene/silicon multilayer is fabricated by electron beam deposition. • It exhibits specific capacity retention over 1000 mA h g−1. • Capacity retention at 100 nm and 7-layer exceeds 90%. • It can be used for lighting of light-emitting diodes. - Abstract: A graphene/silicon (Si) multilayer sandwich structures are fabricated using electron beam (EB) deposition without air exposure. The graphene and Si thin films are formed on Cu current correctors through a continuous process in high-vacuum EB chamber. Synthesized graphene should be suggested to the stacked multiple layer from Raman analysis. The fabricated multilayer films are used as anodes. In the beginning, the half-cell, which used a seven-layer of each thickness 50-nm graphene and Si film, exhibits good specific capacity retention over 1000 mA h g−1 after 30 charge/discharge cycles. The capacity value changed with the number of graphene and Si layers. In this study, the number of layers that exhibited optimal properties is seven. Morphological investigation showed a fine layer-by-layer structure. The relationship between different thicknesses of graphene and Si is investigated at 7 L. A 100-nm thickness exhibited optimal properties. Finally, the optimal 7 L and 100-nm thick graphene/Si exhibited high discharge capacitance >1600 mA h g−1 at a current density of 100 mA g−1 after 30 cycles. Initial coulombic and reversible efficiencies exceed 84%. The capacity retention (30th/1st discharge value) at 100 nm and 7 L exceeds 90%. Finally, the soft package battery is assembled by combining the fabricated graphene and Si electrode as anode, LiCoO2 as cathode, separator and liquid electrolyte. It can be used for commercial light-emitting diode (LED) lighting even under bending status

  1. Neutralization of low energy broad ion beam

    International Nuclear Information System (INIS)

    The paper is devoted to experimental and theoretical investigation of a low energy broad ion beam space charge and current compensation and ion-beam plasma (IBP), which would be created in transport space of the beam. The beam had cylindrical symmetry. The continuous uniform and hole tube like ion beams are used in the experiments. Different channels of electron appearing have been investigated for cases of neutralization due to secondary γ-electrons from the target and by electrons from glow cathode-neutralizer with metal or dielectric target. Results of neutralizing electrons energy distributions function measurements are presented as well as dependences of electron temperature and self-consisted plasma potential vs. beam parameters, ambient gas pressure, neutralizer parameters. Role of the thermoelectrons and dependence of IBP parameters on neutralizer area, location and potential are discussed. Significant role in neutralization of spatial collisional processes has been revealed even in neutralization by thermocathode. On the base of the experimental results self-consistent theoretical model have been developed, which describes the behavior of intense ion beam passing through the neutral gas at low pressure within conductive walls. The collisionless approach is used which means absence of collisional relaxation of the beam. This theory is used to derive the plasma potential and electron temperature within the beam

  2. A pilot study of preoperative continuous infusion 5-fluorouracil, external microwave hyperthermia, and external beam radiotherapy for treatment of locally advanced, unresectable, or recurrent rectal cancer

    International Nuclear Information System (INIS)

    Purpose: To determine the feasibility of combining external beam radiotherapy, continuous infusion 5-fluorouracil (5-FU), and external microwave hyperthermia in patients with locally advanced, unresectable, or recurrent adenocarcinoma of the rectum. Methods and Materials: From 7/95 through 2/99, 15 patients were enrolled in the study. The treatment regimen consisted of continuous infusion 5-FU 250 mg/m2/d 7 days/week beginning on day 1, external beam radiotherapy to the pelvis, 4500 cGy, 180 cGy/d 5 days/week using a 3 or 4-field technique, and external microwave hyperthermia on days 3, 8, 15, 22, and 29. Chemotherapy was stopped on the last day of radiotherapy. Surgical resection, if feasible, was scheduled 3-6 weeks after completing thermochemoradiotherapy. For this regimen to be considered feasible, no more than 2 of the 15 patients should fail to complete therapy due to life-threatening toxicity. Toxicity was scored using National Cancer Institute Criteria. Results: All patients completed the chemoradiotherapy portion of the protocol. Eleven of the 15 patients completed all 5 hyperthermia treatments. Of the 4 patients who did not receive the full course of hyperthermia, only 1 patient had treatment stopped due to life-threatening toxicity. The other 3 patients did not complete hyperthermia due to scheduling errors (n = 2) or patient request (n = 1). Five of 15 patients required a treatment interruption due to toxicity no. >=no. Grade 3. Seven patients experienced lesser degrees of toxicity which did not require treatment interruption. Three patients experienced no side effects. The most common toxicities were dermatitis and diarrhea. Of the 14 patients in whom surgery was planned, 11 (79%) were resectable. There was one pathologic complete response. Conclusions: It is feasible to deliver thermochemoradiotherapy, as prescribed in this study, to patients with locally advanced, unresectable, or recurrent rectal cancer. The therapy is moderately toxic, with one

  3. Women in service uniforms

    OpenAIRE

    Hanna Karaszewska; Maciej Muskała

    2012-01-01

    The article discusses the problems of women who work in the uniformed services with the particular emphasis on the performing of the occupation of the prison service. It presents the legal issues relating to equal treatment of men and women in the workplace, formal factors influencing their employment, the status of women in prison, and the problems of their conducting in the professional role. The article also presents the results of research conducted in Poland and all over the world, on th...

  4. Bivariate Uniform Deconvolution

    OpenAIRE

    Benešová, Martina; van Es, Bert; Tegelaar, Peter

    2011-01-01

    We construct a density estimator in the bivariate uniform deconvolution model. For this model we derive four inversion formulas to express the bivariate density that we want to estimate in terms of the bivariate density of the observations. By substituting a kernel density estimator of the density of the observations we then get four different estimators. Next we construct an asymptotically optimal convex combination of these four estimators. Expansions for the bias, variance, as well as asym...

  5. Uniform random spanning trees

    OpenAIRE

    Pemantle, Robin

    2004-01-01

    There are several good reasons you might want to read about uniform spanning trees, one being that spanning trees are useful combinatorial objects. Not only are they fundamental in algebraic graph theory and combinatorial geometry, but they predate both of these subjects, having been used by Kirchoff in the study of resistor networks. This article addresses the question about spanning trees most natural to anyone in probability theory, namely what does a typical spanning tree look like?

  6. Uniformly hyperbolic control theory

    OpenAIRE

    Kawan, Christoph

    2015-01-01

    This paper gives a summary of a body of work at the intersection of control theory and smooth nonlinear dynamics. The main idea is to transfer the concept of uniform hyperbolicity, central to the theory of smooth dynamical systems, to control-affine systems. Combining the strength of geometric control theory and the hyperbolic theory of dynamical systems, it is possible to deduce control-theoretic results of non-local nature that reveal remarkable analogies to the classical hyperbolic theory ...

  7. Experimental Study and FEM Analysis of Externally Prestressed Steel-Concrete Composite Continuous Beams%体外预应力钢-混凝土组合连续梁的试验研究及有限元分析

    Institute of Scientific and Technical Information of China (English)

    贾远林; 陈世鸣; 王新娣

    2012-01-01

    Unlike simply supported beams under positive moment, the ultimate load carrying capacity of continuous steel-concrete composite beams is usually limited by either the local buckling failure of steel section or the distortional lateral buckling near interior supports, which is because the sleel plate under the negative moment near interior is subjected to compression and inclined to instability. However, the simplified plastic theory taking no account of the instability of the beam will lead to a unconservative result. Four full-scale continuous composite beams were tested, among which two were two-span beams with class 2 cross-section and two were three-span beams with class 3 cross-section. One of the two-span beams was a conventional non-pres-tressed composite beam, and the other was a composite beam preslressed with external tendons in both the positive and negative moment regions. One of the three-span composite beams was non- prestressed, and the other was prestressed only in the negative moment regions with external high-strength tendons. The experimental results indicates that all beams collapsed with the characteristic of concrete crushing in sagging moment, and the web local buckling and distortional buckling of the steel beam. The capacity of beams in positive moment can be calculated by simplified plastic theory, while the capacity of beams in negative moment is affected by section classification divided hy width to thickness ratio of the plate,the simplified calculation method based on the web buckling is agreed well with the experimental results. A numerical analysis was conducted for all the beams considering interface slipping, prestressing force, and so on, which agrees well with the experimental results.Unlike simply supported beams under positive moment, the ultimate load carrying capacity of continuous steel-concrete composite beams is usually limited by either the local buckling failure of steel section or the distortional lateral buckling near

  8. Beam halo in high-intensity beams

    International Nuclear Information System (INIS)

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam

  9. Uniform and reproducible stirring in a microbioreactor

    DEFF Research Database (Denmark)

    Bolic, Andrijana; Eliasson Lantz, Anna; Rottwitt, Karsten;

    role in achieving successful cultivations by promoting uniform process conditions and – for aerobic cultivations – a high oxygen transfer rate. In this contribution, the development of a suitable, reliable and reproducible stirrer in a microbioreactor for batch and continuous cultivation of S...

  10. Uniform distribution of Hasse invariants

    Directory of Open Access Journals (Sweden)

    R. A. Mollin

    1985-03-01

    Full Text Available I. Schur's study of simple algebras around the turn of the century, and subsequent investigations by R. Brauer, E. Witt and others, were later reformulated in terms of what is now called the Schur subgroup of the Brauer group. During the last twenty years this group has generated substantial interest and numerous palatable results have ensued. Among these is the discovery that elements of the Schur group satisfy uniform distribution of Hasse invariants. It is the purpose of this paper to continue an investigation of the latter concept and to highlight certain applications of these results, not only to the Schur group, but also to embeddings of simple algebras and extensions of automorphisms, among others.

  11. Effect of Scanning Beam Profile to Fabricate Fused Fiber Tapers by CO_2 Laser Irradiation Method

    Institute of Scientific and Technical Information of China (English)

    Bayle; Fabien; Luo; Aiping; Marin; Emmanuel; Meunier; Jean-Pierre

    2003-01-01

    Beam uniformity is a crucial building block of CO2 experiments aimed at fusing and stretching optical fibers in a lossless manner. When the irradiation beam is expanded through a galvanometer mirror, ways to achieve beam uniformity are investigated.

  12. Effect of Scanning Beam Profile to Fabricate Fused Fiber Tapers by CO2 Laser Irradiation Method

    Institute of Scientific and Technical Information of China (English)

    Bayle Fabien; Luo Aiping; Marin Emmanuel; Meunier Jean-Pierre

    2003-01-01

    Beam uniformity is a crucial building block of CO2 experiments aimed at fusing and stretching optical fibers in a lossless manner. When the irradiation beam is expanded through a galvanometer mirror, ways to achieve beam uniformity are investigated.

  13. Women in service uniforms

    Directory of Open Access Journals (Sweden)

    Hanna Karaszewska

    2012-12-01

    Full Text Available The article discusses the problems of women who work in the uniformed services with the particular emphasis on the performing of the occupation of the prison service. It presents the legal issues relating to equal treatment of men and women in the workplace, formal factors influencing their employment, the status of women in prison, and the problems of their conducting in the professional role. The article also presents the results of research conducted in Poland and all over the world, on the functioning of women in prison and their relations with officers of the Prison Service, as well as with inmates.

  14. Beam-Beam Effects

    OpenAIRE

    Herr, W; Pieloni, T.

    2016-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  15. Beam-Beam Effects

    CERN Document Server

    Herr, W

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  16. Evaluation of biomolecular distributions in rat brain tissues by means of ToF-SIMS using a continuous beam of Ar clusters.

    Science.gov (United States)

    Nakano, Shusuke; Yokoyama, Yuta; Aoyagi, Satoka; Himi, Naoyuki; Fletcher, John S; Lockyer, Nicholas P; Henderson, Alex; Vickerman, John C

    2016-06-01

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) provides detailed chemical structure information and high spatial resolution images. Therefore, ToF-SIMS is useful for studying biological phenomena such as ischemia. In this study, in order to evaluate cerebral microinfarction, the distribution of biomolecules generated by ischemia was measured with ToF-SIMS. ToF-SIMS data sets were analyzed by means of multivariate analysis for interpreting complex samples containing unknown information and to obtain biomolecular mapping indicated by fragment ions from the target biomolecules. Using conventional ToF-SIMS (primary ion source: Bi cluster ion), it is difficult to detect secondary ions beyond approximately 1000 u. Moreover, the intensity of secondary ions related to biomolecules is not always high enough for imaging because of low concentration even if the masses are lower than 1000 u. However, for the observation of biomolecular distributions in tissues, it is important to detect low amounts of biological molecules from a particular area of tissue. Rat brain tissue samples were measured with ToF-SIMS (J105, Ionoptika, Ltd., Chandlers Ford, UK), using a continuous beam of Ar clusters as a primary ion source. ToF-SIMS with Ar clusters efficiently detects secondary ions related to biomolecules and larger molecules. Molecules detected by ToF-SIMS were examined by analyzing ToF-SIMS data using multivariate analysis. Microspheres (45 μm diameter) were injected into the rat unilateral internal carotid artery (MS rat) to cause cerebral microinfarction. The rat brain was sliced and then measured with ToF-SIMS. The brain samples of a normal rat and the MS rat were examined to find specific secondary ions related to important biomolecules, and then the difference between them was investigated. Finally, specific secondary ions were found around vessels incorporating microspheres in the MS rat. The results suggest that important biomolecules related to cerebral

  17. Ritz analysis of discontinuous beams using local trigonometric functions

    Science.gov (United States)

    Dang, Thi D.; Kapania, Rakesh K.; Patil, Mayuresh J.

    2011-03-01

    The objective of the current paper is to present a Ritz-type analytical model for predicting the behavior of discontinuous beams such as thin-walled beams with cracks and multiply-stepped beams. The beam is discretized in the cracked as well as the un-cracked domains for a cracked thin-walled beam and in uniform beams for a multiple-stepped beam. A set of local trigonometric trial functions is used to define the twist angle for the cracked domain and the un-cracked domains, as well as to define the displacement field for uniform domains. A global equation system of unknown Ritz coefficients is derived by minimizing the Lagrangian functional or the total potential energy. In the present Ritz model, the interface continuity conditions between sub-domains are investigated and enforced into the global equation system using the condensation procedure or the Lagrange multipliers. Examples are presented to illustrate the effectiveness of the current model for free vibration and torsional analysis. Results obtained from the current model are found to agree well with those obtained using a detailed finite element method or with existing results in literature. The proposed model offers an efficient approach to reduce the modeling efforts and computational time required to analyze complex beams with cracks or multiple steps.

  18. Uniformly rotating neutron stars

    CERN Document Server

    Boshkayev, Kuantay

    2016-01-01

    In this chapter we review the recent results on the equilibrium configurations of static and uniformly rotating neutron stars within the Hartle formalism. We start from the Einstein-Maxwell-Thomas-Fermi equations formulated and extended by Belvedere et al. (2012, 2014). We demonstrate how to conduct numerical integration of these equations for different central densities ${\\it \\rho}_c$ and angular velocities $\\Omega$ and compute the static $M^{stat}$ and rotating $M^{rot}$ masses, polar $R_p$ and equatorial $R_{\\rm eq}$ radii, eccentricity $\\epsilon$, moment of inertia $I$, angular momentum $J$, as well as the quadrupole moment $Q$ of the rotating configurations. In order to fulfill the stability criteria of rotating neutron stars we take into considerations the Keplerian mass-shedding limit and the axisymmetric secular instability. Furthermore, we construct the novel mass-radius relations, calculate the maximum mass and minimum rotation periods (maximum frequencies) of neutron stars. Eventually, we compare a...

  19. Should School Nurses Wear Uniforms?

    Science.gov (United States)

    Journal of School Health, 2001

    2001-01-01

    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  20. Skin carcinogenesis following uniform and non-uniform β irradiation

    International Nuclear Information System (INIS)

    Where workers or the general public may be exposed to ionising radiation, the irradiation is rarely uniform. The risk figures and dose limits recommended by the International Commission on Radiological Protection (ICRP) are based largely on clinical and epidemiological studies of reasonably uniform irradiated organs. The paucity of clinical or experimental data for highly non-uniform exposures has prevented the ICRP from providing adequate recommendations. This weakness has led on a number of occasions to the postulate that highly non-uniform exposures of organs could be 100,000 times more carcinogenic than ICRP risk figures would predict. This so-called ''hot-particle hypothesis'' found little support among reputable radiobiologists, but could not be clearly and definitively refuted on the basis of experiment. An experiment, based on skin tumour induction in mouse skin, is described which was developed to test the hypothesis. The skin of 1200 SAS/4 male mice has been exposed to a range of uniform and non-uniform sources of the β emitter 170Tm (Emax ∼ 1 MeV). Non-uniform exposures were produced using arrays of 32 or 8 2-mm diameter sources distributed over the same 8-cm2 area as a uniform control source. Average skin doses varied from 2-100 Gy. The results for the non-uniform sources show a 30% reduction in tumour incidence by the 32-point array at the lower mean doses compared with the response from uniform sources. The eight-point array showed an order-of-magnitude reduction in tumour incidence compared to uniform irradiation at low doses. These results, in direct contradiction to the ''hot particle hypothesis'', indicate that non-uniform exposures produce significantly fewer tumours than uniform exposures. (author)

  1. Extensional Uniformity for Boolean Circuits

    CERN Document Server

    McKenzie, Pierre; Vollmer, Heribert

    2008-01-01

    Imposing an extensional uniformity condition on a non-uniform circuit complexity class C means simply intersecting C with a uniform class L. By contrast, the usual intensional uniformity conditions require that a resource-bounded machine be able to exhibit the circuits in the circuit family defining C. We say that (C,L) has the "Uniformity Duality Property" if the extensionally uniform class C \\cap L can be captured intensionally by means of adding so-called "L-numerical predicates" to the first-order descriptive complexity apparatus describing the connection language of the circuit family defining C. This paper exhibits positive instances and negative instances of the Uniformity Duality Property.

  2. Uniform Reduction to SAT

    CERN Document Server

    Janicic, Predrag

    2010-01-01

    There is a huge number of problems, from various areas, being solved by reducing them to SAT. However, for most applications, translations into SAT are performed by specialized, problem-specific tools. In this paper we describe a novel approach for uniform solving of a wide class of problems by reducing them to SAT. The approach uses a new specification language that combines imperative and declarative programming paradigms. A problem is specified by a test (expressed in an imperative form) that a given set of values indeed makes a solution to the problem. In the solving phase, parameters of the problem are represented by (finite) vectors of propositional formulae and the specification is symbolically executed. An assertion that given values make a solution is transformed to an instance of the SAT problem and passed to a SAT solver. If the formula is satisfiable, its model is transformed back to variables describing the problem, i.e., to a solution of the problem. We also describe a system URSA that implement...

  3. UCT IN UNIFORM

    Directory of Open Access Journals (Sweden)

    D.C. Robertson

    2012-02-01

    Full Text Available 1979 saw the celebration of the 150th anniversary of the founding of an educational establishment in the Cape which was to develop into the University of Cape Town. To mark this anniversary the authors have presented a short history of UCT in uniform, highlighting the multifarious contributions made by UCTstudents and staff. This documented history clearly indicates the valuable contribution that not only UCT but all South African universities and their members have made in the past and will be called to make in the future. Changes in national service policy particularly with regard to urban commandos have resulted in the replacement of the UCT Regiment by the Cape Garrison Artillery. However, the loss of the UCT Regiment itself, certainly does not point to the end of UCT's contribution to the defence of South Africa. For at this very moment, in diverse regiments throughout South Africa, members of the UCT community are making a valiant contribution in answering the call of their country.

  4. Coal Mass Body Building Prestressed Continuous Beam Support Engineering Design and Construction%煤炭大体积建筑体的预应力连续梁支架工程设计与施工

    Institute of Scientific and Technical Information of China (English)

    张直明

    2013-01-01

    This paper discusses the mass construction of prestressed concrete continuous beam support engineering application advantages, specific discussed coal mass body building prestressed continuous beam support engineering design and construction steps, finally to a coal mass body building is simulated and construction security analysis.%文章首先论述了大体积建筑体预应力混凝土连续梁支架工程的应用优点,具体探讨了煤炭大体积建筑体的预应力连续梁支架工程设计与施工步骤,最后对某煤炭大体积建筑体进行了仿真与施工保障分析。

  5. Assessment indices for uniform and non-uniform thermal environments

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Different assessment indices for thermal environments were compared and selected for proper assessment of indoor thermal environments.30 subjects reported their overall thermal sensation,thermal comfort,and thermal acceptability in uniform and non-uniform conditions.The results show that these three assessment indices provide equivalent evaluations in uniform environments.However,overall thermal sensation differs from the other two indices and cannot be used as a proper index for the evaluation of non-uniform environments.The relationship between the percentage and the mean vote for each index is established.

  6. Reflective optics system for uniform spherical illumination.

    Science.gov (United States)

    Phipps, C R; Bodner, S E; Shearer, J W

    1975-04-01

    A reflective optical system is described that permits nearly uniform illumination of a small sphere with one or two laser beams. The primary application of this device is to studies of laser-driven implosion of small targets. Other applications include the production of plasma by optical breakdown of gases for spectroscopic studies and for optimum light collection in intensity-limited plasma diagnostics. Simple calculations show that the intensity mapping properties of this system are not excessively sensitive to variations in the radial intensity distribution nor to departures from diffraction-limited propagation in the input beams. Optical damage and the illuminated solid angle required at the focus determine the size of the device. PMID:20135009

  7. Inverse Limits of Uniform Covering Maps

    OpenAIRE

    LaBuz, Brendon

    2008-01-01

    In ``Rips complexes and covers in the uniform category'' the authors define, following James, covering maps of uniform spaces and introduce the concept of generalized uniform covering maps. Conditions for the existence of universal uniform covering maps and generalized uniform covering maps are given. This paper notes that the universal generalized uniform covering map is uniformly equivalent to the inverse limit of uniform covering maps and is therefore approximated by uniform covering maps....

  8. Tumour dose uniformity in radiotherapy: experimental evidence for cell response to non-uniform irradiation

    International Nuclear Information System (INIS)

    A common goal of radiotherapy is the application of uniform radiation dose to the tumour volume. Such a goal has been formalized by the ICRU (ICRU 50, 1993), based on the assumption that cells respond independently and any under-dosed region represents an area with a higher probability to act as a recurrence site. However, dose distributions provided by intensity-modulated radiotherapy (IMRT) and other techniques offer opportunities to escalate tumour doses and greatly reduce normal tissue doses, with these effects enhanced further if dose non-uniformity is allowed in the tumour. A study of the response of several tumour cell lines has suggested an averaging effect if those cells are exposed to a gradient rather then a uniform dose. A study was performed with cell cultures exposed in a 6 MV X-ray beam in full equilibrium conditions with the beam modulated by a wedge filter. With cell communication channels open, cells exposed at the lower or higher dose ends of the wedge responded as if irradiated to mean dose levels, with the severity of this effect dependent on cell type. A possible explanation for this effect is cellular communication. When cells are irradiated with communication channels physically blocked, the normal dose response experienced under uniform irradiation conditions results. There are significant implications of this result for radiotherapy treatment and prescription, dependent primarily on translation of the results to the clinical setting. The ability to deliver largely non-uniform doses to tumours would greatly facilitate normal tissue avoidance and enhance our ability to escalate doses to tumours. This result can also be used to explain some recent observations regarding dose-response extracted from clinical trial data

  9. The influence of density distribution on the stability of beams

    International Nuclear Information System (INIS)

    We examine the effect of various density distributions in four-dimensional phase space and their projections in real and velocity space on the stability of continuous beams in alternating-gradient transport lines using particle-following computer simulations. We discuss the susceptibility of three different distributions (Kapchinskii-Vladimirskii, bicylinder, and thermal) to third- and higher-order mode instabilities. These distributions are all uniform in real space, but their velocity distributions are different; they also react differently to structure resonances. Velocity distributions of high-current beams tend to evolve to a peaked Gaussian-like form. Is there a specific velocity distribution that is stable and, therefore, the preferred injection distribution for minimizing emittance growth? Forced smoothness or uniformity in real space is necessary for setting up particle simulations of high-current beams so that spurious charge-redistribution emittance growth can be avoided. Is forced smoothness also desirable in four dimensions for continuous beams and possibly in six dimensions for bunched beams? We consider these and related questions

  10. School Uniforms: Esprit de Corps.

    Science.gov (United States)

    Ryan, Rosemary P.; Ryan, Thomas E.

    1998-01-01

    The benefits of school uniforms far outweigh their short-term costs. School uniforms not only keep students safe, but they increase their self-esteem, promote a more positive attitude toward school, lead to improved student behavior, and help blur social-class distinctions. Students are allowed to wear their own political or religious messages,…

  11. Comments on Beckmann's Uniform Reducts

    OpenAIRE

    Cook, Stephen

    2006-01-01

    Arnold Beckmann defined the uniform reduct of a propositional proof system f to be the set of those bounded arithmetical formulas whose propositional translations have polynomial size f-proofs. We prove that the uniform reduct of f + Extended Frege consists of all true bounded arithmetical formulas iff f + Extended Frege simulates every proof system.

  12. Statistical Test for Bivariate Uniformity

    Directory of Open Access Journals (Sweden)

    Zhenmin Chen

    2014-01-01

    Full Text Available The purpose of the multidimension uniformity test is to check whether the underlying probability distribution of a multidimensional population differs from the multidimensional uniform distribution. The multidimensional uniformity test has applications in various fields such as biology, astronomy, and computer science. Such a test, however, has received less attention in the literature compared with the univariate case. A new test statistic for checking multidimensional uniformity is proposed in this paper. Some important properties of the proposed test statistic are discussed. As a special case, the bivariate statistic test is discussed in detail in this paper. The Monte Carlo simulation is used to compare the power of the newly proposed test with the distance-to-boundary test, which is a recently published statistical test for multidimensional uniformity. It has been shown that the test proposed in this paper is more powerful than the distance-to-boundary test in some cases.

  13. Uniform rectifiability and harmonic measure I: Uniform rectifiability implies Poisson kernels in $L^p$

    CERN Document Server

    Hofmann, Steve

    2012-01-01

    We present a higher dimensional, scale-invariant version of a classical theorem of F. and M. Riesz. More precisely, we establish scale invariant absolute continuity of harmonic measure with respect to surface measure, along with higher integrability of the Poisson kernel, for a domain $\\Omega\\subset \\re^{n+1},\\, n\\geq 2$, with a uniformly rectifiable boundary, which satisfies the Harnack Chain condition plus an interior (but not exterior) corkscrew condition. In a companion paper to this one \\cite{HMU}, we also establish a converse, in which we deduce uniform rectifiability of the boundary, assuming scale invariant $L^q$ bounds, with $q>1$, on the Poisson kernel.

  14. Study of beam transport lines for a biomedical research facility at CERN based on LEIR

    CERN Document Server

    Abler, D; Garonna, A; Peach, K

    2014-01-01

    The Low Energy Ion Ring (LEIR) at CERN has been proposed to provide ion beams with magnetic rigidities up to 6.7 T.m for biomedical research, in parallel to its continued operation for LHC and SPS fixed target physics experiments. In the context of this project, two beamlines are proposed for transporting the extracted beam to future experimental end-stations: a vertical beamline for specific low-energy radiobiological research, and a horizontal beamline for radiobiology and medical physics experimentation. This study presents a first linear-optics design for the delivery of 1–5mm FWHM pencil beams and 5 cm 5 cm homogeneous broad beams to both endstations. High field uniformity is achieved by selection of the central part of a strongly defocused Gaussian beam, resulting in low beam utilisation.

  15. A device used in pulsed slow positron beam's stretching

    International Nuclear Information System (INIS)

    A slow positron beam's stretching device has been designed and constructed on Beijing Slow Positron Beam, which based on a 1.3 GeV linac. Positron was storage and stretching use Penning-Trap technique. Measurements show that the positron storage time strongly depends on the vacuum level in Penning Trap tube. Two modes was used to release the positrons from storage part, lowering VC while VB kept constant and rising VB while VC kept constant. This technique makes the pulsed positron beam to a quasi-continuous beam. The energy spread of positrons depend on in release mode. In the latter mode, the authors observe that the energy spread was reduced to a value less than 1.0 eV. The time profile in user-defined waveform is more uniform. It is beneficial to reduce the probability of amplifier pileup especially in the case of measurement with high counting rate. (authors)

  16. Design and Realization of Uniform Fiber Bragg Grating Used in Dense Wavelength Division Multiplexing Systems

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Relation of optical properties in a uniform fiber Bragg grating(FBG) with its grating parameters and the laser beam engraving conditions is analyzed. The principle and method for designing the uniform FBG used in dense wavelength division multiplexing(DWDM) system is given. By adopting the double exposure technique, with a uniform phase mask and Gaussian laser beam, the uniform FBG used in DWDM system is designed and engraved, whose bandwidth of the main reflection band is about 0.4nm and 0.7nm at -5dB and -25dB respectively.

  17. Uniformity of fuel target implosion in Heavy Ion Fusion

    CERN Document Server

    Kawata, S; Suzuki, T; Karino, T; Barada, D; Ogoyski, A I; Ma, Y Y

    2015-01-01

    In inertial confinement fusion the target implosion non-uniformity is introduced by a driver beams' illumination non-uniformity, a fuel target alignment error in a fusion reactor, the target fabrication defect, et al. For a steady operation of a fusion power plant the target implosion should be robust against the implosion non-uniformities. In this paper the requirement for the implosion uniformity is first discussed. The implosion uniformity should be less than a few percent. A study on the fuel hotspot dynamics is also presented and shows that the stagnating plasma fluid provides a significant enhancement of vorticity at the final stage of the fuel stagnation. Then non-uniformity mitigation mechanisms of the heavy ion beam (HIB) illumination are also briefly discussed in heavy ion inertial fusion (HIF). A density valley appears in the energy absorber, and the large-scale density valley also works as a radiation energy confinement layer, which contributes to a radiation energy smoothing. In HIF a wobbling he...

  18. Uniform Acceleration in General Relativity

    CERN Document Server

    Friedman, Yaakov

    2016-01-01

    We extend de la Fuente and Romero's defining equation for uniform acceleration in a general curved spacetime from linear acceleration to the full Lorentz covariant uniform acceleration. In a flat spacetime background, we have explicit solutions. We use generalized Fermi-Walker transport to parallel transport the Frenet basis along the trajectory. In flat spacetime, we obtain velocity and acceleration transformations from a uniformly accelerated system to an inertial system. We obtain the time dilation between accelerated clocks. We apply our acceleration transformations to the motion of a charged particle in a constant electromagnetic field and recover the Lorentz-Abraham-Dirac equation.

  19. Uniform Central Limit Theorems for Multidimensional Diffusions

    CERN Document Server

    Rohde, Angelika

    2010-01-01

    It has recently been shown that there are grave differences in the regularity behavior of the empirical process based on scalar diffusions as compared to the classical empirical process, due to the existence of diffusion local time. Besides establishing strong parallels to classical theory such as Ossiander's bracketing CLT and the general Gin\\'e-Zinn CLT for uniformly bounded families of functions, we find increased regularity also for multivariate ergodic diffusions, assuming that the invariant measure is finite with Lebesgue density $\\pi$. The effect is diminishing for growing dimension but always present. The fine differences to the classical iid setting are worked out using exponential inequalities for martingales and additive functionals of continuous Markov processes as well as the characterization of the sample path behavior of Gaussian processes by means of the generic chaining bound. To uncover the phenomenon, we study a smoothed version of the empirical diffusion process. It turns out that uniform ...

  20. 部分剪力连接预应力连续组合梁抗弯性能试验研究%Experimental study on bending behaviors of prestressed steel concrete continuous composite beams with partial shear connection

    Institute of Scientific and Technical Information of China (English)

    胡少伟; 龚洪波

    2013-01-01

    The static load of four prestressed steel concrete continuous composite beams was tested in order to research the effects of the degree of shear connection on the bending behaviors of prestressed steel concrete continuous composite beams, such as the load-deflection characteristic, the load-slip along the span of beams, the strain distribution along the height of composite section, the load-stress increment of prestressed tendons, the interal force redistribution, the failure mode and the ultimate strength of the structure. The research results show that the deformation and interface slip increase and the bending capacity decreases with the reduction of shear connection, but it is less than the direct proportion of the reduction of shear connection. The bending capacity of two composite beams with the shear connection coefficient of 0. 7 was less than 10 percent compared with the full shear connection. The bending moment modulation value of continuous composite beams also decreases with the reduction of shear connection.%为探究剪力连接程度对预应力钢-混凝土连续组合梁的荷载-跨中挠度特征、沿梁纵向的相对滑移分布规律、沿截面高度的应变分布、预应力增量变化以及连续梁的内力重分布过程、破坏机理与极限强度等的影响,进行了4根预应力钢一混凝土连续组合梁的静载全过程试验研究.研究结果表明,随着剪力连接程度的降低,变形及界面滑移明显增大,承载能力有所降低,但降低程度小于剪力连接的降低程度,2根剪力连接程度系数为0.7的组合梁承载力比完全剪力连接组合梁均降低不到10%,随着剪力连接程度的降低连续梁相应弯矩的调幅值也会降低.

  1. Beam-beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Zholents, A.

    1994-12-01

    The term beam-beam effects is usually used to designate different phenomena associated with interactions of counter-rotating beams in storage rings. Typically, the authors speak about beam-beam effects when such interactions lead to an increase of the beam core size or to a reduction of the beam lifetime or to a growth of particle`s population in the beam halo and a correspondent increase of the background. Although observations of beam-beam effects are very similar in most storage rings, it is very likely that every particular case is largely unique and machine-dependent. This constitutes one of the problems in studying the beam-beam effects, because the experimental results are often obtained without characterizing a machine at the time of the experiment. Such machine parameters as a dynamic aperture, tune dependencies on amplitude of particle oscillations and energy, betatron phase advance between the interaction points and some others are not well known, thus making later analysis uncertain. The authors begin their discussion with demonstrations that beam-beam effects are closely related to non linear resonances. Then, they will show that a non linearity of the space charge field is responsible for the excitation of these resonances. After that, they will consider how beam-beam effects could be intensified by machine imperfections. Then, they will discuss a leading mechanism for the formation of the beam halo and will describe a new technique for beam tails and lifetime simulations. They will finish with a brief discussion of the coherent beam-beam effects.

  2. Sckool Dress Rule, Uniform Policies

    Institute of Scientific and Technical Information of China (English)

    潘志强

    2005-01-01

    Our schools believe that a uniform policy will provide a better environment, promote positive selfesteem, encourage an atmosphere for greater discipline, and increase learning opportunities for students by removing many of the distractions associated with various types of clothing.

  3. Local Rigidity Of Uniform Lattices

    OpenAIRE

    Gelander, Tsachik; Levit, Arie

    2016-01-01

    We establish local topological rigidity for uniform lattices in compactly generated groups, extending the result of Weil from the realm of Lie groups. We generalize the classical local rigidity theorem of Selberg, Calabi and Weil to irreducible uniform lattices in $\\text{Isom}(X)$ where $X$ is a proper $\\text{CAT}(0)$ space with no Euclidian factors, not isometric to the hyperbolic plane. We deduce an analog of Wang's finiteness theorem for certain non-positively curved metric spaces.

  4. THE UNIFORM BOUNDEDNESS PRINCIPLE FOR ARBITRARY LOCALLY CONVEX SPACES

    Directory of Open Access Journals (Sweden)

    CHARLES SWARTZ

    2007-12-01

    Full Text Available We establish uniform boundedness principle for pointwise bounded families of continuous linear operators between locally convex spaces which require no assumptions such as barrelledness on the domain space of the operators. We give applications of the result to separately continuous bilinear operators between locally convex spaces

  5. Beam expansion with specified final distributions

    International Nuclear Information System (INIS)

    The formation of nearly uniformly distributed beams has been accomplished by the use of multipole magnets. Multipole fields, however, are an inappropriate basis for creating precise distributions, particularly since substantial departures from uniformity are produced with a finite number of multipole elements. A more appropriate formalism that allows precise formation of a desired distribution is presented. Design of nonlinear magnets for uniform-beam production and the optics of an accompanying expansion system are presented

  6. Measurement of continuous degradation of a stripper foil during ths operation with 300 kW beam power in the 3-GeV RCS of J-PARC

    International Nuclear Information System (INIS)

    In the 3-GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex, we have clearly measured a continuous degradation of a stripper foil during more than 6 months operation with a beam power of 300 kW. A hybrid-type boron doped carbon stripper foil of 200 μg/cm2 was used for 181 MeV H- stripping injection. In order to know an absolute change of the foil thickness as well as information on the pinhole formation, we precisely measured an absolute change of the partially-stripped H0 and the un-stripped H- waste beams. Two absolutely independent monitor systems were used and the results were found to be very consistent with each other. The foil thickness at the injected beam spot was measured to be gradually thickening and it was more than 10 % thicker at the end compared to the initial thickness, where the measurement accuracy was obtained to be better than 2 %. The missing un-stripped H- were also measured to be gradually increasing due to foil deformation and curling but there was however no clear indication of foil thinning or pinhole formation. (author)

  7. Non-uniform Hyperbolicity and Non-uniform Specification

    CERN Document Server

    Oliveira, Krerley

    2011-01-01

    Let $f$ be a $C^{1+\\alpha}\\,(\\alpha>0)$ diffeomorphism and $\\mu$ be an ergodic hyperbolic measure of $f$. We show that this system $(f,\\mu)$ naturally satisfies non-uniform specification property\\cite{STV}(see Definition \\ref{Def:NS}) and thus we can delete the assumption of non-uniform specification property in the main Theorem \\cite{STV} to establish an inequality between Lyapunov exponents and local recurrence properties. We also discuss generalized non-uniform specification property with respect to arbitrarily finite(infinite) orbit segments. Moreover, these results are also valid for any ergodic hyperbolic measure $\\mu$, in whose Oseledec splitting the stable bundle dominates the unstable bundle on the support of $\\mu$.

  8. Uniform rectifiability and harmonic measure I: Uniform rectifiability implies Poisson kernels in $L^p$

    OpenAIRE

    Hofmann, Steve; Martell, José María

    2012-01-01

    We present a higher dimensional, scale-invariant version of a classical theorem of F. and M. Riesz. More precisely, we establish scale invariant absolute continuity of harmonic measure with respect to surface measure, along with higher integrability of the Poisson kernel, for a domain $\\Omega\\subset \\mathbb{R}^{n+1},\\, n\\geq 2$, with a uniformly rectifiable boundary, which satisfies the Harnack Chain condition plus an interior (but not exterior) corkscrew condition. In a companion paper to th...

  9. Control of fuel target implosion non-uniformity in heavy ion inertial fusion

    CERN Document Server

    Iinuma, T; Kondo, S; Kubo, T; Kato, H; Suzuki, T; Kawata, S; Ogoyski, A I

    2016-01-01

    In inertial fusion, one of scientific issues is to reduce an implosion non-uniformity of a spherical fuel target. The implosion non-uniformity is caused by several factors, including the driver beam illumination non-uniformity, the Rayleigh-Taylor instability (RTI) growth, etc. In this paper we propose a new control method to reduce the implosion non-uniformity; the oscillating implosion acceleration dg(t) is created by pulsating and dephasing heavy ion beams (HIBs) in heavy ion inertial fusion (HIF). The dg(t) would reduce the RTI growth effectively. The original concept of the non- uniformity control in inertial fusion was proposed in (Kawata, et al., 1993). In this paper it was found that the pulsating and dephasing HIBs illumination provide successfully the controlled dg(t) and that dg(t) induced by the pulsating HIBs reduces well the implosion non-uniformity. Consequently the pulsating HIBs improve a pellet gain remarkably in HIF.

  10. 7 CFR 1767.13 - Departures from the prescribed RUS Uniform System of Accounts.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 12 2010-01-01 2010-01-01 false Departures from the prescribed RUS Uniform System of...) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE (CONTINUED) ACCOUNTING REQUIREMENTS FOR RUS ELECTRIC BORROWERS Uniform System of Accounts § 1767.13 Departures from the prescribed RUS Uniform System of...

  11. Nonlinear finite element analysis of fire resistance performance for prestressed concrete continuous beams and slabs%预应力混凝土连续梁板抗火性能非线性分析

    Institute of Scientific and Technical Information of China (English)

    侯晓萌; 郑文忠

    2011-01-01

    A numerical model to simulate loading process of prestressed concrete(PC) continuous beams and slabs at elevated temperature is presented.It is considered that plane sections before bending remain plane after bending.Based on the thermal-mechanical coupling constitutive models of concrete,reinforcing and prestressing steels,the transient strain,creep strain in concrete at time t+1 could be calculated by the stress in concrete at the former step.The coupled constitutive model of concrete could be decoupled,and the reinforcing and prestressing steels were calculated by the same way.Therefore,the moment-curvature relationships of PC beams and slabs subjected to fire can be calculated.The moment of flexure,deflection and support displacement of the beams and slabs imposed by curvature and support reaction together was calculated respectively.The support reaction was calculated by the iteration method until the deflection compatibility equation at the support was satisfied,and the deflection of continuous beams and slabs could be obtained.The deflection of PC continuous beams and slabs subjected to fire calculated by the computer program is verified by correlative fire resistance experiments.Through these studies,it is shown that support and span restraint effect has significant influence on the fire resistance of PC continuous beams and slabs.The mid-span deflection in side spans is larger than that in inner spans.%为模拟预应力混凝土连续梁板在火灾下的受力全过程,认为火灾下预应力混凝土梁板截面总应变符合平截面假定,基于混凝土、普通钢筋和预应力筋的耦合本构关系,用t时刻的混凝土应力计算t+1时刻混凝土的瞬态热应变、高温徐变,钢筋与预应力筋采用相同的解耦方法,可求得火灾下预应力混凝土梁板的弯矩-曲率曲线;对支座反力进行迭代求解,计算梁板在曲率与支座反力共同作用下的弯矩、挠度和支座位移,直至支座位移满

  12. Beam tests of phosphorescent screens

    International Nuclear Information System (INIS)

    Twelve phosphorescent screens were beam tested for linearity, uniformity, low radiation damage and a suitable emitted wavelength for use with television cameras. One screen was chosen for the construction of several intercepting profile monitors which were used during the SLC Ten Sector Tests to measure the emittance and wakefield effects of a damped electron beam

  13. Determination of lead equivalent thickness and uniformity for Radiation Protective Gloves

    International Nuclear Information System (INIS)

    A procedure based on international standard and suited with our facilities was developed in our lab was used to determine lead equivalent thickness and uniformity of radiation protective gloves (RPG). Samples were sent by a Malaysian rubber glove manufacturer company for testing by using three narrow x-ray beam qualities with different size of collimators. Three types of x-ray beam quality were set-up with various thicknesses of copper filters. The calibration graphs were plotted for every X-ray beam qualities with different thickness of lead filters. Five points were selected for every sample in the uniformity test. Results are presented and shown that for lower beam quality, the lead equivalent thickness of the same samples are higher compare to higher beam quality. The uniformities of samples are not quite different for the selected points of the samples. (author)

  14. Manufacturing uniform field silicon drift detector using double boron layer

    International Nuclear Information System (INIS)

    Novel SDDs with continuous junctions on both sides are fabricated using pure boron (PureB) depositions to create a shallow junction in the entrance window side and a continuous rectifying junction with different potentials as function of the drift coordinate in the device side. The SDDs made in this material offer lower leakage current. In addition, continuous SDD designed with two boron layers with different sheet resistances displays uniform electric field

  15. Uniform excitations in magnetic nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Frandsen, Cathrine; Hansen, Mikkel Fougt

    2010-01-01

    We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization...... and the magnetic hyperfine field, in contrast to the Bloch T3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering....

  16. C-V uniformity measurements

    International Nuclear Information System (INIS)

    Ion implantation's unique contributions to FET processing are excellent uniformity and repeatability at low dose. These could be verified on product wafers but were difficult to measure on monitor wafers. This paper presents an MOS technique that integrates the C-V curve directly to obtain part of the implanted dose - the partial dose. This technique is fast and insensitive to measurement noise and dot-diameter variation. It uses standard MOS wafers and processing. Neither photo-defined dots nor special substrates are required. Presently the integral CdV technique for partial dose is used in several FET lines to measure both implant repeatability and uniformity. (orig.)

  17. Uniform excitations in magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Steen Mørup

    2010-11-01

    Full Text Available We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering.

  18. Harmonious coloring of uniform hypergraphs

    OpenAIRE

    Bartłomiej Bosek; Sebastian Czerwiński; Jarosław Grytczuk; Paweł Rzążewski

    2016-01-01

    A \\emph{harmonious coloring} of a $k$-uniform hypergraph $H$ is a vertex coloring such that no two vertices in the same edge share the same color, and each $k$-element subset of colors appears on at most one edge. The \\emph{% harmonious number} $h(H)$ is the least number of colors needed for such a coloring. %These notions arose as a natural extension of a widely studied %topic of harmonious coloring of simple graphs. We prove that $k$-uniform hypergraphs of bounded maxim...

  19. Moment redistribution in continuous beams strentgthened with basalt fiber reinforced polymer%玄武岩纤维布加固连续梁弯矩重分布特征分析

    Institute of Scientific and Technical Information of China (English)

    丁斌

    2014-01-01

    对4根玄武岩纤维布加固的混凝土 T 形截面连续梁和1根对比梁进行抗弯试验,分析了试验梁的破坏模式和各控制截面的弯矩调幅系数.试验结果表明:加固梁跨中截面纵筋屈服前,加固梁和对比梁各控制截面荷载-挠度曲线基本重合;跨中截面纵筋屈服后,加固梁发生了明显的弯矩重分布,跨中截面弯矩调幅系数为0.09~0.22,中支座截面弯矩调幅系数为0.15~0.38;1~3层纤维布加固梁荷载-挠度曲线具有屈服平台,表现出明显的延性破坏特征.%To analyze characteristics of moment redistribution of beams strengthened with BFRP sheets,flexural tests were conducted on one comparative continuous beam and four strengthened RC T-section continuous beams. Failure modes and modulation coefficients were analyzed. The results show that load versus displacement curves of control sections nearly overlap with each other before yielding of longitudinal rebar at mid-span. After the yielding of the rebar,obvious moment redistribution occurs. Moment modulation coefficients of the middle sup-port section ranges from 0. 09 to 0. 22. Moment modulation coefficients of the middle support section ranges from 0. 15 to 0. 38. Beams strengthened with one to three plies of BFRP sheets have a yielding platform in load versus displacement curves,and are subjected to obvious ductility failure.

  20. School Uniforms: Guidelines for Principals.

    Science.gov (United States)

    Essex, Nathan L.

    2001-01-01

    Principals desiring to develop a school-uniform policy should involve parents, teachers, community leaders, and student representatives; beware restrictions on religious and political expression; provide flexibility and assistance for low-income families; implement a pilot program; align the policy with school-safety issues; and consider legal…

  1. Uniform magnetic excitations in nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Hansen, Britt Rosendahl

    2005-01-01

    We have used a spin-wave model to calculate the temperature dependence of the (sublattice) magnetization of magnetic nanoparticles. The uniform precession mode, corresponding to a spin wave with wave vector q=0, is predominant in nanoparticles and gives rise to an approximately linear temperature...... of the sublattice magnetization vectors, results in a contribution to the susceptibility, which increases with increasing temperature....

  2. Nonlinear finite element analysis of prestressed continuous steel-concrete composite beams%预应力钢-混凝土连续组合梁的非线性有限元分析

    Institute of Scientific and Technical Information of China (English)

    陶慕轩; 聂建国

    2011-01-01

    Based on the experimental results of six two-span prestressed continuous steel-concrete composite beams, an elaborate finite element model is proposed for simulating the nonlinear behavior of prestressed continuous composite beams using the commercial FE package MSC. MARC (2005r2). The procedures for element selection, material modeling and monolithic assembly are presented in detail, using an elasto-plastic constitutive model. The numerical model considering both the material and the geometric nonlinearities can fully reflect the complex characteristics such as the change of tendon force, slip effect, redistribution of internal force, stress distribution, curvature distribution, formation of plastic hinges, etc.. As the finite-element results are in good agreement with the test results and the theoretical analysis, the proposed finite-element model provides a tool for nonlinear analysis of prestressed continuous composite beams.%以六根两跨预应力钢-混凝土连续组合梁的系列试验结果为基础,以通用有限元程序MSC.MARC( 2005r2)为平台,提出用于模拟预应力连续组合梁非线性全过程受力行为的精细有限元模型,并给出单元选取、材料建模以及整体组装的详细过程.有限元分析基于弹塑性本构模型,能充分考虑材料非线性和几何非线性,反映结构受力全过程中预应力筋内力变化、滑移效应、内力重分布、应力分布、曲率分布以及塑性铰形成等复杂特性,深入揭示预应力连续组合梁的受力机理和特点.模型计算结果和实测结果以及理论分析结果吻合良好,表现出良好的数值特性.模型对于预应力连续组合梁的精细化分析具有较高的精度和广泛的适用性,为研究预应力连续组合梁受力性能提供了强有力的工具.

  3. Measuring Strain Response Mode Shapes with a Continuous-Scan LDV

    Directory of Open Access Journals (Sweden)

    Anthony B. Stanbridge

    2002-01-01

    Full Text Available A continuous-scan LDV is a convenient means for measuring the response mode shape (ODS of a vibrating surface, particularly in view of the fact that the ODS is automatically derived as a spatial polynomial series. Second spatial derivatives of the deflection equations are therefore easily derived, and these should, in principle, give curvature equations from which, for a beam or plate of known cross-section, stresses and strains can be obtained directly. Unfortunately, the stress and strain distributions depend critically on higher terms in the original ODS series, which are not accurately measured. This problem can be avoided by a method described here, which enables accurate stress and strain distributions to be derived, from a straight-line LDV scan along a uniform beam, using only five terms in the mode-shape polynomial series. A similar technique could be applied to uniform plates but the analysis and the governing equations are rather more complicated.

  4. A RICH with aerogel: a study of refractive index uniformity

    CERN Document Server

    Alemi, M; Calvi, M; Matteuzzi, C; Musy, M; Perego, D L; Easo, S

    2004-01-01

    The use of aerogel as a radiator in the RICH detectors of LHCb is a challenge due to the hot environment of the hadron collider LHC. Large size tiles of silica aerogel were recently produced with unprecedented optical quality for such dimensions. Results of laboratory measurements and beam tests are briefly reported. A description of a method to measure the uniformity of the index of refraction within the tile is given.

  5. Uniformity Analysis for Index of Retail Price

    Institute of Scientific and Technical Information of China (English)

    潘竞红; 曾庆洪; 刘梅英

    2002-01-01

    Using the Hodges-Ajne testing method, the uniformity of China retail price index was tested. The result, that population is submitting to uniform dist ribution, was obtained. The uniformity of CRPI indicates that the general price level is stable in the Ninth Five-Year Plan. Finally, the reasons causing the uniformity was analyzed.

  6. Continuity of Gaussian Local Times

    OpenAIRE

    Cuzick, Jack

    1982-01-01

    Continuity in the time parameter is considered for a natural version of the local time for stationary Gaussian processes. Bounds are given for the local and uniform modulus of continuity which are applicable in cases not covered by Kono, notably when the incremental variance is a regularly varying function of index two.

  7. Uniform pricing and social welfare

    OpenAIRE

    Bertoletti, Paolo

    2005-01-01

    We re-examine the case for uniform pricing in a monopolistic third-degree price-discrimination setting by introducing differentiated costs. A profit-maximizing monopolist could then use price differentiation to reduce the production of the more costly goods, thereby decreasing average cost and increasing welfare. Indeed, monopolistic price differentiation can improve welfare and also aggregate consumer surplus even if, as in the benchmark linear case, total output does not increase. According...

  8. Uniform-droplet spray forming

    Energy Technology Data Exchange (ETDEWEB)

    Blue, C.A.; Sikka, V.K. [Oak Ridge National Lab., TN (United States); Chun, Jung-Hoon [Massachusetts Institute of Technology, Cambridge, MA (United States); Ando, T. [Tufts Univ., Medford, MA (United States)

    1997-04-01

    The uniform-droplet process is a new method of liquid-metal atomization that results in single droplets that can be used to produce mono-size powders or sprayed-on to substrates to produce near-net shapes with tailored microstructure. The mono-sized powder-production capability of the uniform-droplet process also has the potential of permitting engineered powder blends to produce components of controlled porosity. Metal and alloy powders are commercially produced by at least three different methods: gas atomization, water atomization, and rotating disk. All three methods produce powders of a broad range in size with a very small yield of fine powders with single-sized droplets that can be used to produce mono-size powders or sprayed-on substrates to produce near-net shapes with tailored microstructures. The economical analysis has shown the process to have the potential of reducing capital cost by 50% and operating cost by 37.5% when applied to powder making. For the spray-forming process, a 25% savings is expected in both the capital and operating costs. The project is jointly carried out at Massachusetts Institute of Technology (MIT), Tuffs University, and Oak Ridge National Laboratory (ORNL). Preliminary interactions with both finished parts and powder producers have shown a strong interest in the uniform-droplet process. Systematic studies are being conducted to optimize the process parameters, understand the solidification of droplets and spray deposits, and develop a uniform-droplet-system (UDS) apparatus appropriate for processing engineering alloys.

  9. Uniform Practical Nonlinear Output Regulation

    OpenAIRE

    Marconi, Lorenzo; Praly, Laurent

    2008-01-01

    International audience In this paper, we present a solution to the problem of asymptotic and practical semiglobal regulation by output feedback for nonlinear systems. A key feature of the proposed approach is that practical regulation is achieved uniformly with respect to the dimension of the internal model and to the gain of the stabilizer near the zero error manifold. This property renders the approach interesting for a number of real cases by bridging the gap between output regulation t...

  10. Improved flash γ-ray uniformity using a B/sub θ/ lens diode

    International Nuclear Information System (INIS)

    Significantly improved spatial uniformity of bremsstrahlung radiation, relative to a planar-anode diode, is obtained on the 3-MV, 150-kA HELIA accelerator when a B/sub θ/ lens diode is used to actively control the high-power electron beam at the exit of a coaxial, magnetically insulated transmission line. The advantage of this diode over other diodes which only passively control the beam is that better radiation uniformity for less beam loss is possible. Measurements taken on HELIA are shown to agree with theoretical expectations

  11. Nonlinear Finite Element Analysis of Prestressed Continuous Steel-concrete Composite Beams with External Tendons%体外预应力钢-混凝土连续组合梁非线性数值分析

    Institute of Scientific and Technical Information of China (English)

    贾远林; 陈世鸣; 王新娣

    2011-01-01

    基于4根预应力连续组合梁试验,以通用非线性程序ABAQUS为平台,提出了用于模拟预应力连续组合梁非线性全过程受力行为的精细有限元模型.模型综合考虑了几何非线性、材料非线性、支座负弯矩区板件整体失稳和局部失稳等,不仅反映预应力连续组合梁整体性能,还模拟局部效应,深入揭示预应力筋内力变化、滑移效应、内力重分布、板件整体失稳及局部屈曲等复杂特性.通过对模型计算和实测结果的充分对比与校核,表明该模型用于预应力钢-混凝土连续组合梁的精细化分析具有较高精度和广泛通用性,表现出良好的数值特性,为研究预应力连续组合梁受力性能提供了强有力的数值工具.%Based on test analysis of four prestressed steel-concrete beams.allowing for the nonlinearity of geometry and material,the lateral distortional buckling and the plate local buckling a fine and exact finite element stimulation model by ABAQUS is established to study the the nonlinear development of beams, which reflects the overall behavior of the beam and catches the local effect, such as the stress varying in prestressed tendons, the slip, the redistribution of internal forces, the overall instability and local buckling. Compared the results by the FE model with the tests carefully and strictly, the FE model is of excellent numerical function with enoughaccuracy and versatility, which provides a powerful numeral tool for the research of continuous steel-concrete beams prestressed with external tendons.

  12. Uniform rectifiability and harmonic measure II: Poisson kernels in $L^p$ imply uniform rectifiability

    CERN Document Server

    Hofmann, Steve; Uriarte-Tuero, Ignacio

    2012-01-01

    We present the converse to a higher dimensional, scale-invariant version of a classical theorem of F. and M. Riesz. More precisely, for $n\\geq 2$, for an ADR domain $\\Omega\\subset \\re^{n+1}$ which satisfies the Harnack Chain condition plus an interior (but not exterior) Corkscrew condition, we show that absolute continuity of harmonic measure with respect to surface measure on $\\partial\\Omega$, with scale invariant higher integrability of the Poisson kernel, is sufficient to imply uniformly rectifiable of $\\partial\\Omega$.

  13. Thomas Precession by Uniform Acceleration

    CERN Document Server

    Pardy, Miroslav

    2015-01-01

    We determine the nonlinear transformations between coordinate systems which are mutually in a constant symmetrical accelerated motion. The maximal acceleration limit follows from the kinematical origin and it is an analogue of the maximal velocity in special relativity. We derive the dependence of mass, length, time, Doppler effect, Cherenkov effect and transition radiation angle on acceleration as an analogue phenomena in special theory of relativity. The last application of our method is the Thomas precession by uniform acceleration with the possible role in the modern physics and cosmology. The comparison of derived results with other relativistic methods is necessary.

  14. Dynamic two-dimensional beam-pattern steering technique

    Science.gov (United States)

    Zhou, Shaomin; Yeh, Pochi; Liu, Hua-Kuang

    1993-01-01

    A dynamic two-dimensional laser-beam-pattern steering technique using photorefractive holograms in conjunction with electrically addressed spatial light modulators is proposed and investigated. The experimental results demonstrate the dynamic steering of random combinations of basis beam patterns. The proposed method has the advantages of random beam-pattern combination, good beam intensity uniformity, and higher diffraction efficiency compared with conventional methods.

  15. A molecular beam epitaxy facility for in situ neutron scattering

    International Nuclear Information System (INIS)

    A molecular beam epitaxy (MBE) facility has been built to enable in situ neutron scattering measurements during growth of epitaxial layers. While retaining the full capabilities of a research MBE chamber, this facility has been optimized for polarized neutron reflectometry measurements. Optimization includes a compact lightweight portable design, a neutron window, controllable magnetic field, deposition across a large 76 mm diameter sample with exceptional flux uniformity, and sample temperatures continuously controllable from 38 to 1375 K. A load lock chamber allows for sample insertion, storage of up to 4 samples, and docking with other facilities. The design and performance of this chamber are described here.

  16. Mask CD uniformity improvement by electron scanning exposure based Global Loading Effect Correction

    Science.gov (United States)

    Li, Rivan; Tian, Eric; Shi, Irene; Guo, Eric; Lu, Max

    2015-07-01

    Critical Dimension (CD) Uniformity is one of the necessary parameters to assure good performance and reliable functionality of any integrated circuit (IC), and towards the advanced technology node 28nm and beyond, corresponding CD Uniformity becomes more and more crucial. It is found that bad mask CD Uniformity is a significant error source at 28nm process. The CD Uniformity on mask, if not controlled well, will badly impact wafer CD performance, and it has been well-studied that CD Uniformity issue from gate line-width in transistors would affect the device performance directly. In this paper we present a novel solution for mask global CD uniformity error correction, which is called as global loading effect correction (GLEC) method and applied nesting in the mask exposure map during the electron beam exposure. There are factors such as global chip layout, writing sequence and chip pattern density distribution (Global Loading), that work on the whole mask CD Uniformity, especially Global Loading is the key factor related to mask global CD error. From our experimental results, different pattern density distribution on mask significantly influenced the final mask CD Uniformity: the mask with undulating pattern density distribution provides much worse CD Uniformity than that with uniform one. Therefore, a GLEC model based on pattern density has been created to compensate the global error during the electron beam exposure, which has been proved to be efficacious to improve mask global CD Uniformity performance. Furthermore, it 's also revealed that pattern type is another important impact factor, and GLEC coefficient need be modified due to the specific pattern type (e.g. dense line-space only, iso-space only or an average of them) to improve the corresponding mask CD uniformity.

  17. Nonlinear beam-beam resonances

    International Nuclear Information System (INIS)

    Head-on collisions of bunched beams are considered, assuming the two colliding beams have opposite charges. A few experimental observations are described. The single resonance analysis is developed that is applicable to the strong-weak case of the beam-beam interaction. In this case, the strong beam is unperturbed by the beam-beam interaction; motions of the weak beam particles are then analyzed in the presence of the nonlinear electromagnetic force produced by the strong beam at the collision points. The coherent motions of the two coupled strong beams are shown to exhibit distinct nonlinear resonance behavior. 16 refs., 22 figs

  18. Analytical expression for mode-coherence coefficient of a uniformly-distributed wave propagating in different homogeneous media

    OpenAIRE

    NAJI, Noor Ezzulddin

    2011-01-01

    Presented is a derivation of an analytical expression for the mode-coherence coefficients of uniform-distributed wave propagating within different homogeneous media-as in the case of hyperbolic Gaussian beams-and a simple method involving the superposition of two such beams is proposed. The results obtained from this work are very applicable to study and analysis of Hermite-Gaussian beam propagation, especially in the problems of radiation-matter interaction, and laser beam propagatio...

  19. Dense packing on uniform lattices

    CERN Document Server

    Eloranta, Kari

    2009-01-01

    We study the Hard Core Model on the graphs ${\\rm {\\bf \\scriptstyle G}}$ obtained from Archimedean tilings i.e. configurations in $\\scriptstyle \\{0,1\\}^{{\\rm {\\bf G}}}$ with the nearest neighbor 1's forbidden. Our particular aim in choosing these graphs is to obtain insight to the geometry of the densest packings in a uniform discrete set-up. We establish density bounds, optimal configurations reaching them in all cases, and introduce a probabilistic cellular automaton that generates the legal configurations. Its rule involves a parameter which can be naturally characterized as packing pressure. It can have a critical value but from packing point of view just as interesting are the noncritical cases. These phenomena are related to the exponential size of the set of densest packings and more specifically whether these packings are maximally symmetric, simple laminated or essentially random packings.

  20. Attitudes of Parents about School Uniforms.

    Science.gov (United States)

    West, Charles K.; Tidwell, Diane K.; Bomba, Anne K.; Elmore, Patsy Alexander

    1999-01-01

    Responses from 144 parents of fourth graders showed that 56% favored uniforms in public schools; most agreed that uniforms contributed to a conducive learning environment, promoted school spirit, and discouraged violence; and most disagreed that uniforms cost more than other types of clothing. (SK)

  1. Fractal Continuation

    OpenAIRE

    Barnsley, Michael F.; Vince, Andrew

    2012-01-01

    A fractal function is a function whose graph is the attractor of an iterated function system. This paper generalizes analytic continuation of an analytic function to continuation of a fractal function.

  2. Diode laser in-band pumped, efficient 1645 nm continuous-wave and Q-switched Er:YLuAG lasers with near-diffraction-limited beam quality

    International Nuclear Information System (INIS)

    Fiber-like Er:YLuAG laser rods were tested for continuous-wave (CW) and Q-switched operation. Two narrow-band laser diodes emitting at 1532 nm were used as pump sources. The pump power was confined in the laser rods via total internal reflection. In CW mode, a maximum output power of 7.2 W was measured from a 30 mm long Er:YLuAG laser rod, corresponding to an optical–optical efficiency of 26% and a slope efficiency of 78%. Er:YLuAG and Er:YAG lasers were compared experimentally and exhibited comparable performance, while the measured central wavelength of the Er:YLuAG laser was 1644.75 nm, slightly longer than the central wavelength of the Er:YAG laser in the same experimental circumstances. In Q-switched mode, an output energy of 3.5 mJ was obtained from a 25 mm Er:YLuAG laser rod with a pulse duration of 100 ns and a pulse repetition frequency of 100 Hz. The pulsed output had near-diffraction-limited beam quality with M2 values of 1.13 and 1.11 in the x and y directions, respectively. (letter)

  3. Method of electron beam investigation

    Directory of Open Access Journals (Sweden)

    М. V. Derenovsky

    1967-12-01

    Full Text Available In this article the possibility of electron beam testing by a modified method of moving right edge is considered. The description of the working set made for the continuous indication of radial current density distribution on an oscilloscope is given. As an exemple the results of beam measurement under continuous operation are presented.

  4. Uniform current density and divergence control in high power extraction ion diodes

    International Nuclear Information System (INIS)

    A theory of radial beam uniformity in extraction ion diodes is presented. The theory is based on a locally one-dimensional analysis of the diamagnetic compression of magnetic streamlines and the self-consistent determination of the virtual cathode location. The radial dependence of the applied magnetic field is used to determine the critical parameters of this locally one-dimensional treatment. The theory has been incorporated into the ATHETA magnetic field code to allow the rapid evaluation of realistic magnetic field configurations. Comparisons between the theoretical results, simulations with the QUICKSILVER code, and experiments on the PBFA-X accelerator establish the usefulness of this tool for tuning magnetic fields to improve ion beam uniformity. The consequences of poor beam uniformity on the evolution of ion diode instabilities are discussed with supporting evidence from simulations, theory, and experiments. (author). 8 figs., 15 refs

  5. A Uniform Syntax and Discourse Structure

    DEFF Research Database (Denmark)

    Hardt, Daniel

    2013-01-01

    I present arguments in favor of the Uniformity Hypothesis: the hypothesis that discourse can extend syntax dependencies without conflicting with them. I consider arguments that Uniformity is violated in certain cases involving quotation, and I argue that the cases presented in the literature are in...... fact completely consistent with Uniformity. I report on an analysis of all examples in the Copenhagen Dependency Treebanks involving violations of Uniformity. I argue that they are in fact all consistent with Uniformity, and conclude that the CDT should be revised to reflect this....

  6. Spacetime transformations from a uniformly accelerated frame

    International Nuclear Information System (INIS)

    We use the generalized Fermi–Walker transport to construct a one-parameter family of inertial frames which are instantaneously comoving to a uniformly accelerated observer. We explain the connection between our approach and that of Mashhoon. We show that our solutions of uniformly accelerated motion have constant acceleration in the comoving frame. Assuming the weak hypothesis of locality, we obtain local spacetime transformations from a uniformly accelerated frame K′ to an inertial frame K. The spacetime transformations between two uniformly accelerated frames with the same acceleration are Lorentz. We compute the metric at an arbitrary point of a uniformly accelerated frame. (paper)

  7. Beam-beam observations in the Relativistic Heavy Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Laboratory (BNL), Upton, NY (United States); White, S. [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2015-06-24

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been operating since 2000. Over the past decade, thanks to the continuously increased bunch intensity and reduced β*s at the interaction points, the maximum peak luminosity in the polarized proton operation has been increased by more than two orders of magnitude. In this article, we first present the beam-beam observations in the previous RHIC polarized proton runs. Then we analyze the mechanisms for the beam loss and emittance growth in the presence of beam-beam interaction. The operational challenges and limitations imposed by beam-beam interaction and their remedies are also presented. In the end, we briefly introduce head-on beam-beam compensation with electron lenses in RHIC.

  8. Response Uniformity of the ATLAS Liquid Argon Electromagnetic Calorimeter

    CERN Document Server

    Aharrouche, M; Di Ciaccio, L; El Kacimi, M; Gaumer, O; Gouanère, M; Goujdami, D; Lafaye, R; Laplace, S; Le Maner, C; Neukermans, L; Perrodo, P; Poggioli, L; Prieur, D; Przysiezniak, H; Sauvage, G; Wingerter-Seez, I; Zitoun, R; Lanni, F; Lü, L; Ma, H; Rajagopalan, S; Takai, H; Belymam, A; Benchekroun, D; Hakimi, M; Hoummada, A; Gao, Y; Stroynowsk, R; Aleksa, M; Carli, T; Fassnacht, P; Gianotti, F; Hervás, L; Lampl, W; Collot, J; Hostachy, J Y; Ledroit-Guillon, F; Malek, F; Martin, P; Viret, S; Leltchouk, M; Parsons, J A; Simion, S; Barreiro, F; Del Peso, J; Labarga, L; Oliver, C; Rodier, S; Barrillon, P; Benchouk, C; Djama, F; Hubaut, F; Monnier, E; Pralavorio, P; Sauvage, D; Serfon, C; Tisserant, S; Tóth, J; Banfi, D; Carminati, L; Cavalli, D; Costa, G; Delmastro, M; Fanti, M; Mandell, L; Mazzanti, M; Tartarelli, F; Kotov, K; Maslennikov, A; Pospelov, G; Tikhonov, Yu; Bourdarios, C; Fayard, L; Fournier, D; Iconomidou-Fayard, L; Kado, M; Parrour, G; Puzo, P; Rousseau, D; Sacco, R; Serin, L; Unal, G; Zerwas, D; Dekhissi, B; Derkaoui, J; EL Kharrim, A; Maaroufi, F; Cleland, W; Lacour, D; Laforge, B; Nikolic-Audit, I; Schwemling, Ph; Ghazlane, H; Cherkaoui El Moursli, R; Idrissi Fakhr-Eddine, A; Boonekamp, M; Kerschen, N; Mansoulié, B; Meyer, P; Schwindlingy, J; Lund-Jensen, B

    2007-01-01

    The construction of the ATLAS electromagnetic liquid argon calorimeter modules is completed and all the modules are assembled and inserted in the cryostats. During the production period four barrel and three endcap modules were exposed to test beams in order to assess their performance, ascertain the production quality and reproducibility, and to scrutinize the complete energy reconstruction chain from the readout and calibration electronics to the signal and energy reconstruction. It was also possible to check the full Monte Carlo simulation of the calorimeter. The analysis of the uniformity, resolution and extraction of constant term is presented. Typical non-uniformities of 0.5% and typical global constant terms of 0.6% are measured for the barrel and end-cap modules.

  9. Application of the Differential Quadrature Method to the Longitudinal Vibration of Non-Uniform Rods

    OpenAIRE

    Al Kaisy, A.M.A.; Esmaeel, Ramadan A; Nassar, Mohamed M.

    2007-01-01

    Differential Quadrature Method (DQM) has a very wide applications in the field of structural vibration of various elements such as beams, plates, cylindrical shells and tanks. One of the most advantages of the DQM is its simple forms for nonlinear formulations using the Hadamard product. In this paper the free vibration of a general non-uniform rod were studied. The non-dimensional natural frequency and the normalized mode shapes of the non-uniform rod of free and clamped boundary conditions ...

  10. Progress with Tevatron Electron Lens Head-On Beam-Beam Compensation

    International Nuclear Information System (INIS)

    Tevatron electron lenses have been successfully used to mitigate bunch-to-bunch differences caused by longrange beam-beam interactions. For this purpose, the electron beam with uniform transverse density distribution was used. Another planned application of the electron lens is the suppression of tune spread due to head-on beam-beam collisions. For this purpose, the transverse distribution of the E- beam must be matched to that of the antiproton beam. In 2009, the Gaussian profile electron gun was installed in one of the Tevatron electron lenses. We report on the first experiments with non-linear beam-beam compensation. Discussed topics include measurement and control of the betatron tune spread, importance of the beam alignment and stability, and effect of electron lens on the antiproton beam lifetime.

  11. Discovery of Uniformly Expanding Universe

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2012-01-01

    Full Text Available Saul Perlmutter and the Brian Schmidt – Adam Riess teams reported that their Friedmann-model GR-based analysis of their supernovae magnitude-redshift data re- vealed a new phenomenon of “dark energy” which, it is claimed, forms 73% of the energy / matter density of the present-epoch universe, and which is linked to the further claim of an accelerating expansion of the universe. In 2011 Perlmutter, Schmidt and Riess received the Nobel Prize in Physics “for the discovery of the accelerating ex- pansion of the Universe through observations of distant supernovae”. Here it is shown that (i a generic model-independent analysis of this data reveals a uniformly expanding universe, (ii their analysis actually used Newtonian gravity, and finally (iii the data, as well as the CMB fluctuation data, does not require “dark energy” nor “dark matter”, but instead reveals the phenomenon of a dynamical space, which is absent from the Friedmann model.

  12. A note on the complementarity of uniform emission standards and monitoring strategies.

    OpenAIRE

    Rousseau, Sandra; Arguedas, Carmen

    2009-01-01

    Despite the well-known static cost-inefficiency of uniform emission standards to control pollution, governments continue to use them in a variety of settings. In this paper, we show that inspection agencies can sometimes use their informational advantage to design monitoring strategies that complement uniform emission standards in restoring efficiency.

  13. Continuous Problem of Function Continuity

    Science.gov (United States)

    Jayakody, Gaya; Zazkis, Rina

    2015-01-01

    We examine different definitions presented in textbooks and other mathematical sources for "continuity of a function at a point" and "continuous function" in the context of introductory level Calculus. We then identify problematic issues related to definitions of continuity and discontinuity: inconsistency and absence of…

  14. Historical Account And Branching To Rarefied Gas Dynamics Of Atomic and Molecular Beams : A Continuing And Fascinating Odyssey Commemorated By Nobel Prizes Awarded To 23 Laureates In Physics And Chemistry

    Science.gov (United States)

    Campargue, Roger

    2005-05-01

    This Historical Account derived in part from D. R. Herschbach was presented as an opening lecture of the Molecular Beam Session organized at the 24th International Symposium on Rarefied Gas Dynamics held in Bari, Italy, in July 2004. The emphasis is on the impressive results due to the molecular beam techniques in the last century. The first section summarizes the historical beam experiments performed by 14 Nobel Prize laureates having used the thermally effusive sources to establish the basic principles of Modern Physics. The second section is on the branching of Molecular Beams to Rarefied Gas Dynamics having permitted to investigate the physics of supersonic free jets and transform the molecular beam techniques. Finally, the last section relates the spectacular molecular beam experiments in helium free jet ultracooling, molecular spectroscopy, chemical reaction dynamics, clustering and modification of low density matter, and biomolecule mass spectrometry, rewarded by nine Nobel Prizes in Chemistry from 1986 to 2002.

  15. Total Skin Electron Irradiation: Evaluation of Dose Uniformity

    International Nuclear Information System (INIS)

    Total Skin Electron Beam Irradiation (TSEI) is one of the most sophisticated treatment techniques of modern radiation oncology practice. TSEI is used in cutaneous T-cell lymphoma, mycosis fungoides (MF), and Kaposi sarcoma. The objective of TSEI is to uniformly deliver a specified dose over the entire skin surface down to a particular depth. However, considerable technical and dosimetric difficulties exist in achieving this goal due to patient and treatment machine factors. Thermoluminescent dosimetry (TLD) measurements are usually performed to evaluate dose distribution throughout the body. This paper presents the in vivo dosimetric data of 67 treatments on 58 patients with MF, treated with TSEI

  16. Electron beam experiments at Maryland University

    International Nuclear Information System (INIS)

    An experimental study of the stability of intense electron beams is described. The purpose is to determine the emittance growth associated with aberrations arising from the non-uniform transverse density distribution in the beam, and to compare measurements with the results of computer simulations

  17. Design and performance of high uniformity linear filament electron gun

    Science.gov (United States)

    Iqbal, Munawar; Fazal-e-Aleem

    2006-10-01

    We describe new features and results from the previously reported [M. Iqbal et al., Rev. Sci. Instrum. 74, 4616 (2003)] thermionic long (up to 140mm) cathode, electromagnetically focused electron beam gun. The gun which was tested up to 50kW (5000mA×10kV) achieves power density of 33kW/cm2 at the target. The cathode temperature and emission current was uniform over a length of 100mm of the cathode. The beam density profile along the line cathode strongly relates to the temperature distribution along the line cathode. The gun has a remarkable application in heat treatment of large surface area and to coat large substrate surfaces at much faster evaporation rates with lower cost.

  18. Refractive index of silica aerogel: Uniformity and dispersion law

    International Nuclear Information System (INIS)

    Two methods for the measurement of the uniformity of the refractive index n within a single block of silica aerogel are described. One is based on the deflection of a laser beam induced by transverse index gradients. The second exploits the Cherenkov effect, measuring the emission angle of photons radiated by 500 MeV electrons traversing the aerogel. The beam can scan the full aerogel surface providing information on point to point variations of n. The measurement of the dispersion law n(λ) is also reported. An Xe lamp coupled to a diffraction grating provides the monochromatic source. The index for each λ is measured by the prism method at a corner of an aerogel sample. A Sellmeier functional form for n(λ) is assumed, and the parameters best fitting the experimental data are given

  19. Illumination uniformity requirements for direct drive inertial confinement fusion

    International Nuclear Information System (INIS)

    The requirements for laser uniformity are discussed in terms of the ell-mode spectrum. It is shown that the choice of smoothing methods can significantly alter this spectrum and that this choice should be made in the context of the target physics. Although two dimensional smoothing by spectral dispersion yields a high quality near field beam profile, it results in poor smoothing for low spatial frequency. The partially coherent light method (fiber smoothing) leads to superior smoothing at low spatial frequencies, but has very poor near field beam quality. As a result, it may be desirable to use partially coherent light during the driver pulse foot (at low intensity and when minimizing the laser imprint is critical) and smoothing by spectral dispersion during the main pulse

  20. Bessel Beams

    OpenAIRE

    McDonald, Kirk T

    2000-01-01

    Scalar Bessel beams are derived both via the wave equation and via diffraction theory. While such beams have a group velocity that exceeds the speed of light, this is a manifestation of the "scissors paradox" of special relativty. The signal velocity of a modulated Bessel beam is less than the speed of light. Forms of Bessel beams that satisfy Maxwell's equations are also given.

  1. Fuel Target Implosion in Ion beam Inertial Confinement Fusion

    CERN Document Server

    Kawata, Shigeo

    2015-01-01

    The numerical results for the fuel target implosion are presented in order to clarify the target physics in ion beam inertial fusion. The numerical analyses are performed for a direct-driven ion beam target. In the paper the following issues are studied: the beam obliquely incidence on the target surface, the plasma effect on the beam-stopping power, the beam particle energy, the beam time duration, the target radius, the beam input energy and the non-uniformity effect on the fuel target performance. In this paper the beam ions are protons.

  2. Uniformly balanced words with linear complexity and prescribed letter frequencies

    Directory of Open Access Journals (Sweden)

    Valérie Berthé

    2011-08-01

    Full Text Available We consider the following problem. Let us fix a finite alphabet A; for any given d-uple of letter frequencies, how to construct an infinite word u over the alphabet A satisfying the following conditions: u has linear complexity function, u is uniformly balanced, the letter frequencies in u are given by the given d-uple. This paper investigates a construction method for such words based on the use of mixed multidimensional continued fraction algorithms.

  3. Beam shaping for holographic techniques

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

    2014-09-01

    Uniform intensity of laser radiation is very important in holographic and interferometry technologies, therefore transformation of typical Gaussian distribution of a TEM00 laser to flat-top (top hat) is an actual technical task, it is solved by applying beam shaping optics. Holography and interferometry have specific requirements to a uniform laser beam, most important of them are flatness of phase front and extended depth of field. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality demanding holography and interferometry. We suggest applying refractive field mapping beam shapers piShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. This approach is used in SLM-based technologies of Computer Generated Holography, Dot-Matrix mastering of security holograms, holographic data storage, holographic projection, lithography, interferometric recording of Volume Bragg Gratings. High optical quality of resulting flat-top beam allows applying additional optical components to vary beam size and shape, thus adapting an optical system to requirements of a particular application. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in holographic systems. Examples of real implementations and experimental results will be presented as well.

  4. Partially polarized Gaussian Schell-model beams

    Science.gov (United States)

    Gori, F.; Santarsiero, M.; Piquero, G.; Borghi, R.; Mondello, A.; Simon, R.

    2001-01-01

    We consider a class of beams that are both partially polarized and partially coherent from the spatial standpoint. They are characterized by a correlation matrix whose elements have the same form as the mutual intensity of a Gaussian Schell-model beam. We focus our attention on those beams that would appear identical to ordinary Gaussian Schell-model beams in a scalar treatment. After establishing some inequalities that limit the choice of the matrix parameters, we study the main effects of propagation. Starting from the source plane, in which the beam is assumed to be uniformly polarized, we find that in the course of propagation the degree of polarization generally becomes non-uniform across a typical section of the beam. Furthermore, we find that the intensity distribution at the output of an arbitrarily oriented linear polarizer is Gaussian shaped at the source plane whereas it can be quite different at other planes.

  5. School uniforms: tradition, benefit or predicament?

    OpenAIRE

    Van Aardt, Annette Marie; Wilken, Ilani

    2012-01-01

    This article focuses on the controversies surrounding school uniforms. Roleplayers in this debate in South Africa are parents, learners and educators, and arguments centre on aspects such as identity, economy and the equalising effect of school uniforms, which are considered in the literature to be benefits. Opposing viewpoints highlight the fact that compulsory uniforms infringe on learners’ constitutional rights to self-expression. The aim of this research was to determine the perspectives ...

  6. Cultural Inertia and Uniformity in Organizations

    OpenAIRE

    Carrillo, Juan D; Gromb, Denis

    2002-01-01

    We analyse aspects of the structure of organizational culture. We show that old and culturally uniform organizations are prone to cultural inertia; that is they are reluctant to adopt a different culture in response to a change in the environment. Cultural uniformity can be beneficial because the associated inertia protects and therefore encourages culture-specific investments by agents within the organization. We also explore the model’s implications for such issues as cultural uniformity wi...

  7. Polychromatic and rotating beams of light

    International Nuclear Information System (INIS)

    Beams of light with rotating polarization or mode patterns can be viewed as superpositions of components with a well-defined angular momentum ℎm per photon, each having a frequency shift m times the rotation frequency. Such beams can also be created after passing a monochromatic beam through rotating optical elements. We discuss the properties of the angular momentum of such beams, both for a rotating polarization and a rotating amplitude pattern. We also consider beams where the polarization is not uniform

  8. On the Compactly Locally Uniformly Rotund Points of Orlicz Spaces

    Indian Academy of Sciences (India)

    Lili Chen; Yunan Cui

    2007-11-01

    In this paper, locally uniformly rotund points and compactly locally uniformly rotund points are introduced. Moreover, criteria for compactly locally uniformly rotund points in Orlicz spaces are given.

  9. High direct drive illumination uniformity achieved by multi-parameter optimization approach: a case study of Shenguang III laser facility.

    Science.gov (United States)

    Tian, Chao; Chen, Jia; Zhang, Bo; Shan, Lianqiang; Zhou, Weimin; Liu, Dongxiao; Bi, Bi; Zhang, Feng; Wang, Weiwu; Zhang, Baohan; Gu, Yuqiu

    2015-05-01

    The uniformity of the compression driver is of fundamental importance for inertial confinement fusion (ICF). In this paper, the illumination uniformity on a spherical capsule during the initial imprinting phase directly driven by laser beams has been considered. We aim to explore methods to achieve high direct drive illumination uniformity on laser facilities designed for indirect drive ICF. There are many parameters that would affect the irradiation uniformity, such as Polar Direct Drive displacement quantity, capsule radius, laser spot size and intensity distribution within a laser beam. A novel approach to reduce the root mean square illumination non-uniformity based on multi-parameter optimizing approach (particle swarm optimization) is proposed, which enables us to obtain a set of optimal parameters over a large parameter space. Finally, this method is applied to improve the direct drive illumination uniformity provided by Shenguang III laser facility and the illumination non-uniformity is reduced from 5.62% to 0.23% for perfectly balanced beams. Moreover, beam errors (power imbalance and pointing error) are taken into account to provide a more practical solution and results show that this multi-parameter optimization approach is effective. PMID:25969321

  10. Continuously variable focal length lens

    Science.gov (United States)

    Adams, Bernhard W; Chollet, Matthieu C

    2013-12-17

    A material preferably in crystal form having a low atomic number such as beryllium (Z=4) provides for the focusing of x-rays in a continuously variable manner. The material is provided with plural spaced curvilinear, optically matched slots and/or recesses through which an x-ray beam is directed. The focal length of the material may be decreased or increased by increasing or decreasing, respectively, the number of slots (or recesses) through which the x-ray beam is directed, while fine tuning of the focal length is accomplished by rotation of the material so as to change the path length of the x-ray beam through the aligned cylindrical slows. X-ray analysis of a fixed point in a solid material may be performed by scanning the energy of the x-ray beam while rotating the material to maintain the beam's focal point at a fixed point in the specimen undergoing analysis.

  11. Continuing Care

    Science.gov (United States)

    ... Care Obesity at Midlife May Speed Alzheimer’s Onset Hello from my mom Easing the Behavior Problems of ... Managers Continuing Care FOR MORE ARTICLES CLICK HERE Hello from my mom Common Estate Planning Errors Alzheimer’s ...

  12. Business continuity

    International Nuclear Information System (INIS)

    This presentation deals with the following keypoints: Information Technology (IT) Business Continuity and Recovery essential for any business; lessons learned after Sept. 11 event; Detailed planning, redundancy and testing being the key elements for probability estimation of disasters

  13. The effect of inducing uniform Cu growth on formation of electroless Cu seed layer

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Taeho; Kim, Myung Jun; Park, Kyung Ju; Kim, Kwang Hwan; Choe, Seunghoe [School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Lee, Young-Soo [Department of Environmental Engineering, Kwangwoon University, Nowon-gu, Seoul 139–701 (Korea, Republic of); Kim, Jae Jeong, E-mail: jjkimm@snu.ac.kr [School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2014-08-01

    The uniformity of Cu growth on Pd nanocatalysts was controlled by using organic additives in the formation of electroless Cu seed layers. Polyethylene glycol (PEG, Mw. 8000) not only reduced the deposition rate but also improved the uniformity of Cu growth on each Pd nanocatalyst during the seed layer formation. The stronger suppression effect of PEG on Cu than on Pd reduced the difference in the deposition rate between the two surfaces, resulting in the uniform deposition. Meanwhile, bis(3-sulfopropyl) disulfide degraded the uniformity by strong and nonselective suppression. The sheet resistance measurement and atomic force microscopy imaging revealed that the uniform Cu growth by PEG was more advantageous for the formation of a thin and smooth Cu seed layer than the non-uniform growth. The uniform Cu growth also had a positive influence on the subsequent Cu electrodeposition: the 60-nm-thick electrodeposited Cu film on the Cu seed layer showed low resistivity (2.70 μΩ·cm), low surface roughness (6.98 nm), and good adhesion strength. - Highlights: • Uniform Cu growth on Pd was achieved in formation of electroless Cu seed layer. • PEG addition to electroless bath improved the uniformity of Cu growth on Pd. • A thin, smooth and continuous Cu seed layer was obtained with PEG. • Adhesion strength of the Cu seed layer was also improved with PEG. • The uniformity improvement positively affected subsequent Cu electrodeposition.

  14. Systematic experiments on the mismatch induced halo formation using non-neutral electron plasmas in a uniform magnetic field

    International Nuclear Information System (INIS)

    Non-neutral electron plasmas confined in a uniform magnetic field can be used to simulate a beam dynamics in a uniform focusing channel. Here, a halo formation due to a mismatch induced on an electric confinement potential (harmonic potential) is reported. A beam halo is measured with a conventional beam imaging system composed of a phosphor screen and a charge-coupled device (CCD) camera. Obtained results show that the growth rate of a halo is a few tens microseconds in the present experimental condition. (author)

  15. Methods for obtaining a uniform volume concentration of implanted ions

    International Nuclear Information System (INIS)

    Three simple practical methods of irradiations with high energy particles providing the conditions for obtaining a uniform volume concentration of the implanted ions in the massive samples are described in the present paper. Realization of the condition of two-sided irradiation of a plane sample during its rotation in the flux of the projectiles is the basis of the first method. The use of free air as a filter with varying absorbent ability due to movement of the irradiated sample along ion beam brought to the atmosphere is at the basis of the second method of uniform ion alloying. The third method for obtaining a uniform volume concentration of the implanted ions in a massive sample consists of irradiation of a sample through the absorbent filter in the shape of a foil curved according to the parabolic law moving along its surface. The first method is the most effective for obtaining a great number of the samples, for example, for mechanical tests, the second one - for irradiation in different gaseous media, and the third one - for obtaining high concentrations of the implanted ions under controlled (regulated) thermal and deformation conditions. 2 refs., 7 figs

  16. Principles of the fifth order tuning of beam expanders

    International Nuclear Information System (INIS)

    An analytical treatment of the third and fifth order optics of beam expanders is described, which allows precise tuning of the optical elements of the beam line, and efficient optimization of the beam uniformizing at the extended target. An application to a two-dimensional expander is given as an illustration. (authors)

  17. A School Uniform Program That Works.

    Science.gov (United States)

    Loesch, Paul C.

    1995-01-01

    According to advocates, school uniforms reduce gang influence, decrease families' clothing expenditures, and help mitigate potentially divisive cultural and economic differences. Aiming to improve school climate, a California elementary school adopted uniforms as a source of pride and affiliation. This article describes the development of the…

  18. School Dress Codes and Uniform Policies.

    Science.gov (United States)

    Anderson, Wendell

    2002-01-01

    Opinions abound on what students should wear to class. Some see student dress as a safety issue; others see it as a student-rights issue. The issue of dress codes and uniform policies has been tackled in the classroom, the boardroom, and the courtroom. This Policy Report examines the whole fabric of the debate on dress codes and uniform policies…

  19. School Uniform Policies: Students' Views of Effectiveness.

    Science.gov (United States)

    McCarthy, Teresa M.; Moreno, Josephine

    2001-01-01

    Focus-group interviews of New York City middle-school students about their perceptions of the effectiveness of the school-uniform policy. Finds that students' perceptions of the effects of school-uniform policy on school culture varied considerably with those intended by the principal. (Contains 40 references.) (PKP)

  20. School Uniforms and Discourses on Childhood.

    Science.gov (United States)

    Bodine, Ann

    2003-01-01

    This ethnographic study examined the introduction of school uniforms in the public schools of one California city. Findings indicated that the uniform issue intersected with issues such as student safety and violence, family stress, egalitarianism, competitive dressing, and a power struggle over shaping the childhood environment. It was concluded…

  1. Uniformity in a Dual Assessment System

    OpenAIRE

    Chicoine, David L.; Giertz, J. Fred

    1988-01-01

    Variation in property tax assessment uniformity is studied using data from a "dual" assessment structure where county assessment authority overlaps township assessing responsibility and elected local assessors work with appointed county assessment officers. Particular attention is given to the impact of the size and organization of assessment jurisdictions on assessment uniformity.

  2. Some results on uniform arithmetic circuit complexity

    DEFF Research Database (Denmark)

    Frandsen, Gudmund Skovbjerg; Valence, Mark; Barrington, David A. Mix

    1994-01-01

    polynomial-size unbounded fan-in arithmetic circuits satisfying a natural uniformity constraint (DLOGTIME-uniformity). A 1-input and 1-output arithmetic function over the fieldsF2n may be identified with ann-input andn-output Boolean function when field elements are represented as bit strings. We prove that...

  3. Deposition uniformity inspection in IC wafer surface

    International Nuclear Information System (INIS)

    This paper focuses on the task of automatic visual inspection of color uniformity on the surface of integrated circuits (IC) wafers arising from the layering process. The oxide thickness uniformity within a given wafer with a desired target thickness is of great importance for modern semiconductor circuits with small oxide thickness. The non-uniform chemical vapor deposition (CVD) on a wafer surface will proceed to fail testing in Wafer Acceptance Test (WAT). Early detection of non-uniform deposition in a wafer surface can reduce material waste and improve production yields. The fastest and most low-priced inspection method is a machine vision-based inspection system. In this paper, the proposed visual inspection system is based on the color representations which were reflected from wafer surface. The regions of non-uniform deposition present different colors from the uniform background in a wafer surface. The proposed inspection technique first learns the color data via color space transformation from uniform deposition of normal wafer surfaces. The individual small region statistical comparison scheme then proceeds to the testing wafers. Experimental results show that the proposed method can effectively detect the non-uniform deposition regions on the wafer surface. The inspection time of the deposited wafers is quite compatible with the atmospheric pressure CVD time

  4. Radionic Non-uniform Stable Black Strings

    OpenAIRE

    Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro

    2003-01-01

    Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of solutions is demonstrated using the catastrophe theory. The black strings are shown to be non-uniform.

  5. Radionic Non-Uniform Black Strings

    Science.gov (United States)

    Tamaki, T.; Kanno, S.; Soda, J.

    Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of solutions is demonstrated using the catastrophe theory. The black strings are shown to be non-uniform.

  6. A uniform parametrization of moment tensors

    Science.gov (United States)

    Tape, Walter; Tape, Carl

    2015-09-01

    A moment tensor is a 3 × 3 symmetric matrix that expresses an earthquake source. We construct a parametrization of the 5-D space of all moment tensors of unit norm. The coordinates associated with the parametrization are closely related to moment tensor orientations and source types. The parametrization is uniform, in the sense that equal volumes in the coordinate domain of the parametrization correspond to equal volumes of moment tensors. Uniformly distributed points in the coordinate domain therefore give uniformly distributed moment tensors. A cartesian grid in the coordinate domain can be used to search efficiently over moment tensors. We find that uniformly distributed moment tensors have uniformly distributed orientations (eigenframes), but that their source types (eigenvalue triples) are distributed so as to favour double couples.

  7. Laser Non-Uniform Heating of Moving Thin Wires Below the Biot Number Criterion of Uniform Temperature

    Science.gov (United States)

    Wickramasooriya, Thiwanka; Vaidyanathan, Raj; Kar, Aravinda

    2016-06-01

    An analytic solution is obtained for three-dimensional quasi-steady state temperature distribution during laser heating of moving thin wires. The wire moves at a constant speed through a vacuum chamber, which is back-filled with an inert gas such as argon, and a laser beam of rectangular cross-section is incident on the wire. The ambient gas provides a convection heat transfer mechanism, which yields a Biot number, Bi, for the heating process to determine whether the temperature distribution would be uniform or nonuniform in the cross-section of the wire. Generally, the criterion of Bi less than 0.1 is applied to assume spatially uniform temperature distribution in a solid. The temperature distribution is determined for different Bi numbers and the variation of the temperature in the azimuthal direction is analyzed. The method of solution involves the Fourier transform in the azimuthal direction and the Hankel transform in the radial direction for a three-dimensional quasi-steady state heat conduction equation containing an advection term that accounts for the motion of the wire. The thermal and optical properties of the material is assumed to be constant in the temperature range of this study. The heat loss due to radiation heat transfer between the wire surface and the surrounding environment is neglected due to the small laser-heated surface area. Using this model, the temperature profile is studied for different process parameters such as the incident laser power, laser beam profile, Biot number, and wire speed.

  8. 基于Kriging模型的钢管混凝土连续梁拱桥有限元模型修正%CFST arch/continuous beam bridge FEM model updating based on Kriging model

    Institute of Scientific and Technical Information of China (English)

    胡俊亮; 颜全胜; 郑恒斌; 崔楠楠; 余晓琳

    2014-01-01

    A new method for FEM updating based on Kriging model was developed.The Kriging model is a linear unbiased minimum variance estimation to the unknown data in a region according to some characteristic information of region’s samples which have similar features with the unknown data.This method can obtain higher accuracy predicted results based on a small number of samples.Through a planar truss FEMupdating example,the feasibility and accuracy of the Kriging model were verified.And then the Kriging model was applied to a concrete-filled-steel-tubular (CFST)arch/continuous beam bridge FEM updating and the results were compared with those by the method of genetic algorithm (GA) combined with BP neural network.The analysis results show that the Kriging model needs only a certain amount of measured frequency data for FEM updating.There is no iterative calculation like in the FEM,which will exhaust much calculation time in updating program.This method can accurately predict the modal information outside the active frequency range.The results testify the high computational efficiency,accuracy and feasibility of the method applied in actual engineering.%提出基于Kriging模型的有限元模型修正方法。Kriging模型为据区域内若干信息样品某种特征数据对该区域同类特征未知数作线性无偏、最小方差估计方法,其只用少量样本即可获得较高精度预测结果。用Kriging模型对平面桁架进行有限元模型修正,验证该方法的可行性与准确性;对一连续梁拱桥进行模型修正,并与GA算法、BP神经网络方法模型修正结果比较分析。Kriging模型仅需一定量测量频率信息即可完成模型修正,能避免修正过程中进行有限元模型迭代计算。结果表明,该方法能准确预测有效频率范围(active frequency range)外模态信息,计算效率、精度较高,可用于工程实践。

  9. Study on improvement of the laser uniformity transformation of overlapping-image waveguide cavity

    Institute of Scientific and Technical Information of China (English)

    Zebin Fan; Junchang Li; Chongguang Li; Kun Ma

    2005-01-01

    @@ After propagating through the overlapping-image integral mirror, the interference fringe is a major factor that affects the uniformity of the image plane. In this paper, a He-Ne laser is used as light source, and the complex amplitude of the incident laser beam is modulated by an alternating electric field controlled vibrating mirror that is placed before the optical system. The experimental results show that after propagating through the overlapping-image integral mirror, not only the contrast of the interference fringes on the image plane is depressed, but also the uniformity of the intensity distribution of the transformed light beam is improved. Finally, based on the experimental results, two optical systems that can be applied to high power laser uniformity transformation are presented.

  10. Continuity theory

    CERN Document Server

    Nel, Louis

    2016-01-01

    This book presents a detailed, self-contained theory of continuous mappings. It is mainly addressed to students who have already studied these mappings in the setting of metric spaces, as well as multidimensional differential calculus. The needed background facts about sets, metric spaces and linear algebra are developed in detail, so as to provide a seamless transition between students' previous studies and new material. In view of its many novel features, this book will be of interest also to mature readers who have studied continuous mappings from the subject's classical texts and wish to become acquainted with a new approach. The theory of continuous mappings serves as infrastructure for more specialized mathematical theories like differential equations, integral equations, operator theory, dynamical systems, global analysis, topological groups, topological rings and many more. In light of the centrality of the topic, a book of this kind fits a variety of applications, especially those that contribute to ...

  11. Multi beam laser target illumination

    International Nuclear Information System (INIS)

    In order to compress matter to high densities by the application of intense pulses of laser energy it is necessary for the implosion of the target to be both stable and spherical. This imposes certain constraints on the uniformity of illumination of the target, and, this in turn places requirements on the illuminating optics and the laser beam quality. This report discusses the uniformity of illumination of a spherical target as provided by a variety of optical systems and for different numbers of laser beams and beam profiles. The results are compared with similar conclusions obtained by other workers. An alternative presentation of the calculations is given which is believed to be a more realistic estimate of the uniformity. Comments are made on the approximations that have been assumed and the results likely to be obtained from the full treatment are discussed. The effects of this non-uniform illumination on the target implosion are considered using the linear theory of the Rayleigh-Taylor instability. Finally, comments are made on other factors of a more practical nature which also govern the final choice of illumination system and the scope of experiments made possible by such a system. (author)

  12. Existence and convergence of fixed points for mappings of asymptotically nonexpansive type in uniformly convex W-hyperbolic spaces

    Directory of Open Access Journals (Sweden)

    Cui Yunan

    2011-01-01

    Full Text Available Abstract Uniformly convex W-hyperbolic spaces with monotone modulus of uniform convexity are a natural generalization of both uniformly convexnormed spaces and CAT(0 spaces. In this article, we discuss the existence of fixed points and demiclosed principle for mappings of asymptotically non-expansive type in uniformly convex W-hyperbolic spaces with monotone modulus of uniform convexity. We also obtain a Δ-convergence theorem of Krasnoselski-Mann iteration for continuous mappings of asymptotically nonexpansive type in CAT(0 spaces. MSC: 47H09; 47H10; 54E40

  13. Fuel Target Implosion in Ion beam Inertial Confinement Fusion

    OpenAIRE

    Kawata, Shigeo

    2015-01-01

    The numerical results for the fuel target implosion are presented in order to clarify the target physics in ion beam inertial fusion. The numerical analyses are performed for a direct-driven ion beam target. In the paper the following issues are studied: the beam obliquely incidence on the target surface, the plasma effect on the beam-stopping power, the beam particle energy, the beam time duration, the target radius, the beam input energy and the non-uniformity effect on the fuel target perf...

  14. Report for muon production target with the 300-kW proton beam operation at MUSE/MLF/J-PARC

    International Nuclear Information System (INIS)

    The most intense pulsed muon beam will be generated by a 3-GeV 333-microA proton beam on a muon target made of 20-mm thick isotropic graphite (IG-430) in J-PARC/MUSE (Muon Science Establishment). The energy deposited by a 1-MW proton beam is estimated to be 3.9 kW on the muon target. The first muon beam was successfully generated on September 26th, 2008. Gradually upgrading the beam intensity, continuous 300-kW proton beam operation was started in January of 2013. The temperatures of the principle components have been measured and recorded through thermocouples and a control system. The lifetime of the muon target is determined by a proton-irradiation damage of the graphite. Even in the 300-kW operation to July of 2013, the radiation damage was anticipated to surpass the lifetime. Therefore, the position of the proton beam has been moved to eight surrounding positions every three weeks to distribute the radiation damage uniformly to a wider area. The position-control is named EXILE operation. The variation of the temperatures at the muon target has been monitored. In this report, the status of proton beam operation and the lifetime extension of the muon target will be described. (author)

  15. Continuity check

    Energy Technology Data Exchange (ETDEWEB)

    Woof, M.

    2002-10-01

    This paper looks into both safety and technological developments in continuous mining. Manufacturers covered include Hydraphase, Eimco, Deilmann-Haniel, DBT and Joy. A recent Health and Safety Executive report mentioned three in incidents of frictional ignition of flammable gas by cutting equipment in a five year period to April 1999. 4 photos.

  16. Uniform supersaturated design and its construction

    Institute of Scientific and Technical Information of China (English)

    方开泰; 葛根年; 刘民千

    2002-01-01

    Supersaturated designs are factorial designs in which the number of main effects is greater than the number of experimental runs. In this paper, a discrete discrepancy is proposed as a measure of uniformity for supersaturated designs, and a lower bound of this discrepancy is obtained asa benchmark of design uniformity. A construction method for uniform supersaturated designs via resolvable balanced incomplete block designs is also presented along with the investigation of properties of the resulting designs. The construction method shows a strong link between these two different kinds of designs.

  17. Whiteness formula in CIELAB uniform color space

    Institute of Scientific and Technical Information of China (English)

    Guoxin He; Mingxun Zhou

    2007-01-01

    @@ Many attempts have been made to standardize the calculation of whiteness. Whiteness formulas currently in use satisfactorily characterize the appearance of commercial whiteness. However, they have poor correlations with the observers' evaluations, and are often unsuccessful in assessing tinted white samples.A whiteness formula in the CIELAB uniform color space is developed in this paper. Several whiteness formulas are analyzed and compared. The experimental results show that the whiteness formula in the CIELAB uniform color space agrees well with the visual ranking, and it is superior to the CIE whiteness formula and the others in visual correlativity, uniformity and applicability.

  18. Forerunning mode transition in a continuous waveguide

    CERN Document Server

    Slepyan, Leonid; Mishuris, Gennady

    2014-01-01

    We have discovered a new, forerunning mode transition as the periodic transition wave propagating in a uniform continuous waveguide. The latter is represented by an elastic beam separating from the elastic foundation under the action of sinusoidal waves. The critical displacement is the separation criterion. We show that the steady-state separation mode, where the separation front speed is independent of the wave amplitude, exists only in a bounded speed-dependent range of the wave amplitude. As the latter exceeds the critical value the steady-state mode is replaced by a more complicated regime with porous-like local separations emerging at a distance ahead of the main transition front. The crucial feature of this simple model is that the wave group speed is greater than the phase speed. The analytical solution allows us to show in detail how the steady-state mode transforms into the forerunning one. The established forerunning mode studied numerically manifests itself as a periodic process. As the incident w...

  19. Extension-matrix representation theory of light beams and Beauregard effect

    CERN Document Server

    Li, Chunfang

    2007-01-01

    A light beam in free space is found to be representable by an integral over a vectorial angular spectrum that is expressed in terms of a two-form angular spectrum and an extension matrix. There exists one freedom to be chosen for the general extension matrix. Two types are considered. In the paraxial approximation, one describes uniformly polarized beams, and the other describes non-uniformly polarized beams, including the axially symmetric polarized beam as a special case. It is shown that the non-uniformly polarized beams bear the Beauregard effect that was speculated more than 40 years ago.

  20. Continuation calculus

    Directory of Open Access Journals (Sweden)

    Bram Geron

    2013-09-01

    Full Text Available Programs with control are usually modeled using lambda calculus extended with control operators. Instead of modifying lambda calculus, we consider a different model of computation. We introduce continuation calculus, or CC, a deterministic model of computation that is evaluated using only head reduction, and argue that it is suitable for modeling programs with control. It is demonstrated how to define programs, specify them, and prove them correct. This is shown in detail by presenting in CC a list multiplication program that prematurely returns when it encounters a zero. The correctness proof includes termination of the program. In continuation calculus we can model both call-by-name and call-by-value. In addition, call-by-name functions can be applied to call-by-value results, and conversely.

  1. Recycled Paper Beam Sculpture

    Science.gov (United States)

    Keller, Kristin; Tabacchi, Jo

    2011-01-01

    As art department budgets across the country continue to shrink, art teachers are increasingly on the lookout for inexpensive materials that can be used to teach a range of concepts. In this article, the authors describe a newspaper beam tower project inspired by the book, "The Wonderful Towers of Watts" by Patricia Zelver. There are many more…

  2. Electrode structure for uniform corona discharge

    Science.gov (United States)

    Gange, R. A.; Steinmetz, C. C.

    1976-01-01

    Single corona-discharge needle is used to apply uniform charge to thermoplastic medium in holograph-storage system. Needle is connected to flat transparent electrode that is parallel to thermoplastic.

  3. Orbifoldization, covering surfaces and uniformization theory

    CERN Document Server

    Bántay, P

    1998-01-01

    The connection between the theory of permutation orbifolds, covering surfaces and uniformization is investigated, and the higher genus partition functions of an arbitrary permutation orbifold are expressed in terms of those of the original theory.

  4. Radiation of non-uniform plasma column

    International Nuclear Information System (INIS)

    The solution of the problem of thermal radiation is obtained for the case of non-uniform plasma column approximated by an arbitrary number of uniform cylindrical layers. Plasma is described within the frame of hydrodynamic model with gas-kinetic pressure of electrons and dynamics of molecular sub-system taken into account. The power of radiation is calculated on the basis of Langevin approach by using the reciprocity theorem to solve the problem of fluctuation field excitation by by random sources

  5. Uniform and Robust Peptoid Microsphere Coatings

    OpenAIRE

    Servoss, Shannon L.; Phillip Blake; Melissa L. Hebert; Dhaval S. Shah

    2013-01-01

    Peptoids that are helical and partially water soluble have been shown to self-assemble into microspheres when the peptoid solution is dried on a silicon substrate. Such microsphere coatings have great potential for use in biosensor technologies, specifically to increase the surface area for binding. However, in order to be useful, the peptoids must consistently form uniform coatings. In this study we investigated the effects of various coating protocol parameters on the uniformity of the resu...

  6. LIMITING BEHAVIOR OF UNIFORM RECURSIVE TREES

    Institute of Scientific and Technical Information of China (English)

    Su Chun; Feng Qunqiang; Liu Jie

    2007-01-01

    The authors consider the limiting behavior of various branches in a uniform recursive tree with size growing to infinity. The limiting distribution of ζn,m, the number of branches with size m in a uniform recursive tree of order n, converges weakly to a Poisson distribution with parameter 1/m with convergence of all moments. The size of any large branch tends to infinity almost surely.

  7. Beam - cavity interaction beam loading

    International Nuclear Information System (INIS)

    The interaction of a beam with a cavity and a generator in cyclic accelerators or storage rings is investigated. Application of Maxwell's equations together with the nonuniform boundary condition allows one to get an equivalent circuit for a beam-loaded cavity. The general equation for beam loading is obtained on the basis of the equivalent circuit, and the beam admittance is calculated. Formulas for power consumption by a beam-loaded cavity are derived, and the optimal tuning and coupling factor are analyzed. (author)

  8. Underdense plasma lenses for focusing particle beams

    International Nuclear Information System (INIS)

    Plasma lenses are of interest for providing ultra-strong focusing of particle beams in order to enhance the luminosity of a high-energy linear collider. Previous work has explored the selfpinch of e+ or e- beams as they pass through an overdense slab of passive plasma (i.e., plasma density much greater than the beam density). Here the authors examine the focusing of beams in an underdense plasma through physical and particle simulation models. In this regime the plasma dynamics becomes highly non-linear and differs for e+ and e- beams. For e- beams the plasma electrons are almost completely expelled by the beam's space charge leaving a uniform column of ion charge that provides the focusing force. Compared to the overdense lens, the underdense lens has the advantages that spherical aberrations, longitudinal aberrations, and plasma contribution to background in the detectors are all greatly reduced. 10 refs., 4 figs., 1 tab

  9. 轨道交通曲线连续钢—混组合梁抗剪分析%Shear Analysis of Curved Continuous Steel/Concrete Composite Beams Adopted in Urban Rail Transit

    Institute of Scientific and Technical Information of China (English)

    阙孜

    2013-01-01

    In the steel/concrete composite beam calculation, according to the specifications, shear stresses are calculated for solid beam transverse bending, without torsional shear stress. For curved composite beams torques are large, it is necessary to study whether torsional shear stress effect should be taken into account. Considering an engineering example, the free torsional shear stresses are calculated; bending shear stresses are respectively calculated for a closed thin - walled member and a solid beam, and the calculation results were compared and analyzed for the formulation of a reasonable computation method.%论述在钢混组合梁计算中,规范中按实体梁横向弯曲剪应力计算,没有扭转剪应力计算的规定.曲线组合梁的扭矩较大,讨论是否需要考虑扭转剪应力的影响.结合工程实例,计算分析自由扭转剪应力,按闭口薄壁构件和实体梁分别计算弯曲剪应力,并对计算结果进行对比分析,提出合理的计算方法.

  10. Frozen Beams

    CERN Document Server

    Okamoto, Hiromi

    2005-01-01

    In general, the temperature of a charged particle beam traveling in an accelerator is very high. Seen from the rest frame of the beam, individual particles randomly oscillate about the reference orbit at high speed. This internal kinetic energy can, however, be removed by introducing dissipative interactions into the system. As a dissipative process advances, the beam becomes denser in phase space or, in other words, the emittance is more diminished. Ideally, it is possible to reach a "zero-emittance" state where the beam is Coulomb crystallized. The space-charge repulsion of a crystalline beam just balances the external restoring force provided by artificial electromagnetic elements. In this talk, general discussion is made of coasting and bunched crystalline beams circulating in a storage ring. Results of molecular dynamics simulations are presented to demonstrate the dynamic nature of various crystalline states. A possible method to approach such an ultimate state of matter is also discussed.

  11. POLYNOMIAL SOLUTIONS TO PIEZOELECTRIC BEAMS(Ⅰ)--SEVERAL EXACT SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    DING Hao-jiang; JIANG Ai-min

    2005-01-01

    For the orthotropic piezoelectric plane problem, a series of piezoelectric beams is solved and the corresponding exact solutions are obtained with the trial-anderror method on the basis of the general solution in the case of three distinct eigenvalues, in which all displacements, electrical potential, stresses and electrical displacements are expressed by three displacement functions in terms of harmonic polynomials. These problems are rectangular beams having rigid body displacements and identical electrical potential, rectangular beams under uniform tension and electric displacement as well as pure shearing and pure bending, beams of two free ends subjected to uniform electrical potential on the upper and lower surfaces.

  12. Diagnosing light ion beam diodes

    International Nuclear Information System (INIS)

    This lecture begins with a discussion of diagnostics in ion-beam diodes. This will include electromagnetic measurements, measurements of the electron cloud, and measurements of anode plasmas. A few minutes will be spent on diagnostics of distributed ion sources required for one class of ion diodes, the plasma-filled versions, which require high-density, highly ionized sources of very uniform plasma. The measurements of the beam characteristics will then be discussed. This will be broken into two regions; the region near the diode where diagnostics are generally extensions of those used in other fields; and the region near focus where new diagnostics have been developed

  13. First and Second Sound Modes in a Uniform Fermi Gas

    Institute of Scientific and Technical Information of China (English)

    HUANG Bei-Bing; WAN Shao-Long

    2009-01-01

    First and second sound modes in a uniform fermionic atom gas with Feshbach resonance are investigated in the frame of a two-fluid model at finite temperature. All thermodynamic quantities are calculated for a given thermodynamic potential The analytical results for thermodynamic quantities and sound velocities in BCS and BEC limits are obtained. The numerical rcsults show that there exists a continuous interpolation for sound velocities of the first and second sound modes at fixed T/Tc between BCS and BEC limits. The existence of the second sound mode indicates the existence of superfluidity.

  14. Beam loading

    CERN Document Server

    Gamp, Alexander

    2013-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.

  15. Focusing of truncated Gaussian beams

    Science.gov (United States)

    Horváth, Zoltán L.; Bor, Zsolt

    2003-07-01

    It is shown that the focusing of truncated Gaussian beams can be treated by the same manner as uniform spherical waves, i.e., the diffraction integral can be expressed by the Lommel functions, which offers a very efficient way for the calculation of the three-dimensional light distribution near focus. All the expressions for the uniform spherical waves hold good for Gaussian beams if the first variable in the Lommel functions is extended to the complex domain. The intensity distribution depending on the Fresnel number and the truncation coefficient is calculated. The location of the first few minima and maxima of the intensity in focal plane is given for different values of the truncation coefficient. The phase behavior depending on the truncation coefficient is studied.

  16. Controlled uniform coating from the interplay of Marangoni flows and surface-adsorbed macromolecules

    CERN Document Server

    Kim, Hyoungsoo; Um, Eujin; Jacobi, Ian; Button, Ernie; Stone, Howard A

    2016-01-01

    Surface coatings and patterning technologies are essential for various physicochemical applications. In this Letter, we describe key parameters to achieve uniform particle coatings in binary solutions: First, multiple sequential Marangoni flows, set by solute and surfactant simultaneously, prevent non-uniform particle distributions and continuously mix suspended materials during droplet evaporation. Second, we show the importance of particle-surface interactions that can be established by surface-adsorbed macromolecules. To achieve a uniform deposit in a binary mixture a small concentration of surfactant and surface-adsorbed polymer (0.05 wt% each) is sufficient, which offers a new physicochemical avenue for control of coatings.

  17. Effect of the laser intensity profile on the shock non-uniformity in a directly driven spherical target

    Science.gov (United States)

    Temporal, Mauro; Canaud, Benoit; Garbett, Warren J.; Ramis, Rafael

    2015-10-01

    > An axially symmetric laser beam configuration irradiating a spherical capsule has been considered in the context of inertial confinement fusion (ICF). The laser beams are located at co-latitudes 49° and 131° and mimic the quad positions in the second cone of the Laser Mégajoule Facility. The capsule is directly irradiated by the laser beams whose energy deposition generates a nearly spherical shock wave. Two-dimensional hydrodynamic numerical simulations have been performed to analyse the non-uniformity of the shock wavefront launched inward throughout the target. Different laser intensity profiles, calculated by the illumination model, have been tested. The performance, in terms of shock non-uniformity, has been compared, and it is found that with an appropriate choice of the laser intensity profile it is possible to control the shock non-uniformity at early times.

  18. Wide-aperture laser beam measurement using transmission diffuser: errors modeling

    Science.gov (United States)

    Matsak, Ivan S.

    2015-06-01

    Instrumental errors of measurement wide-aperture laser beam diameter were modeled to build measurement setup and justify its metrological characteristics. Modeled setup is based on CCD camera and transmission diffuser. This method is appropriate for precision measurement of large laser beam width from 10 mm up to 1000 mm. It is impossible to measure such beams with other methods based on slit, pinhole, knife edge or direct CCD camera measurement. The method is suitable for continuous and pulsed laser irradiation. However, transmission diffuser method has poor metrological justification required in field of wide aperture beam forming system verification. Considering the fact of non-availability of a standard of wide-aperture flat top beam modelling is preferred way to provide basic reference points for development measurement system. Modelling was conducted in MathCAD. Super-Lorentz distribution with shape parameter 6-12 was used as a model of the beam. Using theoretical evaluations there was found that the key parameters influencing on error are: relative beam size, spatial non-uniformity of the diffuser, lens distortion, physical vignetting, CCD spatial resolution and, effective camera ADC resolution. Errors were modeled for 90% of power beam diameter criteria. 12-order Super-Lorentz distribution was primary model, because it precisely meets experimental distribution at the output of test beam forming system, although other orders were also used. The analytic expressions were obtained analyzing the modelling results for each influencing data. Attainability of <1% error based on choice of parameters of expression was shown. The choice was based on parameters of commercially available components of the setup. The method can provide up to 0.1% error in case of using calibration procedures and multiple measurements.

  19. A uniform parameterization of moment tensors

    Science.gov (United States)

    Tape, C.; Tape, W.

    2015-12-01

    A moment tensor is a 3 x 3 symmetric matrix that expresses an earthquake source. We construct a parameterization of the five-dimensional space of all moment tensors of unit norm. The coordinates associated with the parameterization are closely related to moment tensor orientations and source types. The parameterization is uniform, in the sense that equal volumes in the coordinate domain of the parameterization correspond to equal volumes of moment tensors. Uniformly distributed points in the coordinate domain therefore give uniformly distributed moment tensors. A cartesian grid in the coordinate domain can be used to search efficiently over moment tensors. We find that uniformly distributed moment tensors have uniformly distributed orientations (eigenframes), but that their source types (eigenvalue triples) are distributed so as to favor double couples. An appropriate choice of a priori moment tensor probability is a prerequisite for parameter estimation. As a seemingly sensible choice, we consider the homogeneous probability, in which equal volumes of moment tensors are equally likely. We believe that it will lead to improved characterization of source processes.

  20. 7 CFR 1007.61 - Computation of uniform prices.

    Science.gov (United States)

    2010-01-01

    ..., the market administrator shall compute a uniform butterfat price, a uniform skim milk price, and a... section. (b) Uniform skim milk price. The uniform skim milk price per hundredweight, rounded to the... paragraph (a) of this section times 3.5 pounds of butterfat; and (2) Multiply the uniform skim milk...

  1. 7 CFR 1131.61 - Computation of uniform prices.

    Science.gov (United States)

    2010-01-01

    ..., the market administrator shall compute a uniform butterfat price, a uniform skim milk price, and a... section. (b) Uniform skim milk price. The uniform skim milk price per hundredweight, rounded to the... paragraph (a) of this section times 3.5 pounds of butterfat; and (2) Multiply the uniform skim milk...

  2. 7 CFR 1005.61 - Computation of uniform prices.

    Science.gov (United States)

    2010-01-01

    ... month, the market administrator shall compute a uniform butterfat price, a uniform skim milk price, and...) and (a)(2) of this section. (b) Uniform skim milk price. The uniform skim milk price per hundredweight... paragraph (a) of this section times 3.5 pounds of butterfat; and (2) Multiply the uniform skim milk...

  3. 7 CFR 1006.61 - Computation of uniform prices.

    Science.gov (United States)

    2010-01-01

    ..., the market administrator shall compute a uniform butterfat price, a uniform skim milk price, and a... section. (b) Uniform skim milk price. The uniform skim milk price per hundredweight, rounded to the... paragraph (a) of this section times 3.5 pounds of butterfat; and (2) Multiply the uniform skim milk...

  4. A practical technique for the generation of highly uniform LIPSS

    Energy Technology Data Exchange (ETDEWEB)

    Ardron, Marcus, E-mail: ma745@hw.ac.uk [School of Engineering and Physical Sciences, Heriot Watt University, Edinburgh EH14 4AS (United Kingdom); Renishaw PLC, Research Avenue North, Riccarton, Edinburgh EH14 4AP (United Kingdom); Weston, Nick [Renishaw PLC, Research Avenue North, Riccarton, Edinburgh EH14 4AP (United Kingdom); Hand, Duncan [School of Engineering and Physical Sciences, Heriot Watt University, Edinburgh EH14 4AS (United Kingdom)

    2014-09-15

    Highlights: • Formation of uniform LIPSS on stainless steel is greatly aided by polishing in an orthogonal direction to the expected periodic features. Roughness of a sample surface must avoid vector spatial frequency content near to that of the expected LIPSS. • A very simple polishing technique was found to be suitable. • Surface finish requirement was predicted based on the efficacy factor theory; one of the few theories to give qualitatively strong agreement with experimental evidence in a field that is not fully explained by current theories. • Modelled and experimental results presented. • Using a line focused beam from an ultrafast laser facilitated the rapid production of relatively large areas of LIPSS with a modest laser repetition rate. - Abstract: Laser-induced periodic surface structures (LIPSS) can be reliably produced with ultrashort (<10 ps) laser pulses given fluence near the ablation threshold. Neat, parallel, uniform structures are harder to reproduce. Electrodynamic models show a field at normal incidence interacts with the surface resulting in periodicity in intensity along the surface in the direction of the incident E-field producing ridges and toughs on the surface orthogonal to the E-field. A completely smooth surface offers nothing to perturb the eventual periodic feature formation but is very difficult to achieve: we have demonstrated that simply avoiding surface roughness components near the frequency and direction of the emergent features significantly improves uniform feature production. An appropriate unidirectional polishing process can be realised using an inexpensive spinning cloth wheel. By using a cylindrical lens we were also able to process stainless steel surfaces at 5 mm{sup 2} s{sup −1} so indicating useful industrial potential.

  5. Beam optics test stand

    International Nuclear Information System (INIS)

    The authors have constructed a beam optics test stand in order to study adaptive charged particle optics. A low energy, continuous electron beam is used to model a high energy negative ion beam. In addition, the beam can be used as a diagnostic probe to study the correction of spherical aberrations in a solenoid lens. The authors test stand design stresses versatility. The conical glass vacuum system has reentrant electron and diagnostic chambers that allow immediate experimental modifications. As an integral part of the vacuum system, the solenoid lens also serves as structural support for grid focusing systems. Vacuum pumping is provided by an 8'' cryopump and the entire system can be moved about freely. Computer control and data acquisition are interfaced to the beam control and diagnostics. A post acceleration grid and deflection plates have been added to a commercial electron gun to produce a 10 keV beam at 100 μA. The diagnostics consist of phosphor screens, a charge-coupled photodiode array, and an image dissector

  6. Array illumination with minimal non-uniformity based on generalized phase contrast

    DEFF Research Database (Denmark)

    Palima, Darwin; Glückstad, Jesper

    2009-01-01

    The generalized phase contrast method (GPC) has been previously shown to be an efficient technique for generating array illumination and is thus highly suitable for such applications as dynamic multiple beam trapping and optical micromanipulation. However, projected arrays usually exhibit intensity...... output spots to improve uniformity. This is combined with matching corrections to the phase shift introduced by the phase contrast filter. Results from numerical experiments show that the array illumination uniformity error improves from over 40% to less than 1% while maintaining the efficiency prior...

  7. Simulation of intense beam bunching using 3D PIC method

    International Nuclear Information System (INIS)

    Most of the ion sources produce continuous beam of charged particles. In a cyclotron using such an external ion source, only a small fraction of the injected continuous beam is accepted in the central region for further acceleration. By transforming the continuous beam into a suitably bunched beam using a buncher prior to injection, the amount of accepted particles in the central region of cyclotron can be increased. To compress the continuous beam longitudinally one needs to impose a velocity modulation at the buncher gap which results in density modulation as the beam advances. In the case of low beam current the velocity modulation of the beam has very little effect on the transverse envelope of the beam. However, in the case of high intensity beams, the space-charge force introduces much collective behaviour and increase of current in the specified bunch width affects the transverse dynamics

  8. Uniform dimension results for Gaussian random fields

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Let X = {X(t),t ∈ RN} be a Gaussian random field with values in Rd defined by X(t) =(X1(t),...,Xd(t)), t ∈ RN.(1) The properties of space and time anisotropy of X and their connections to uniform Hausdorff dimension results are discussed.It is shown that in general the uniform Hausdorff dimension result does not hold for the image sets of a space-anisotropic Gaussian random field X.When X is an(N,d)-Gaussian random field as in(1),where X1,...,Xd are independent copies of a real valued,centered Gaussian random field X0 which is anisotropic in the time variable.We establish uniform Hausdorff dimension results for the image sets of X.These results extend the corresponding results on one-dimensional Brownian motion,fractional Brownian motion and the Brownian sheet.

  9. Ultrasonic transducer design for uniform insonation

    International Nuclear Information System (INIS)

    Techniques used in transducer development for acoustical imaging have been evaluated for the purpose of producing broad, uniform ultrasonic fields from planar radiators. Such fields should be useful in hyperthermia, physical therapy, and ultrasonic bioeffects studies. Fourier inversion of the circ function yielded a source velocity distribution proportional to (P/r) exp ((-ik/2Z) (2Z/sup 2/+r/sup 2/)) J/sub 1/(krP/Z), where r is the radial source coordinate, k is the wave number, and P is the desired radius of uniform insonation at a depth Z in water. This source distribution can be truncated without significantly degrading the solution. A simpler solution consists of exponentially shading the edge of an otherwise uniformly excited disk transducer. This approach was successfully approximated experimentally

  10. Uniform and Robust Peptoid Microsphere Coatings

    Directory of Open Access Journals (Sweden)

    Shannon L. Servoss

    2013-06-01

    Full Text Available Peptoids that are helical and partially water soluble have been shown to self-assemble into microspheres when the peptoid solution is dried on a silicon substrate. Such microsphere coatings have great potential for use in biosensor technologies, specifically to increase the surface area for binding. However, in order to be useful, the peptoids must consistently form uniform coatings. In this study we investigated the effects of various coating protocol parameters on the uniformity of the resulting peptoid microsphere coatings, including (i solvent, (ii administration technique, and (iii drying environment. In addition, we investigated the robustness of the coatings as well as the potential for using a glass substrate. These studies show that uniform, robust peptoid microsphere coatings can be formed using protic solvents, a full coverage administration technique, and drying in open air on silicon or glass substrates.

  11. Asymmetric Laguerre-Gaussian beams

    Science.gov (United States)

    Kovalev, A. A.; Kotlyar, V. V.; Porfirev, A. P.

    2016-06-01

    We introduce a family of asymmetric Laguerre-Gaussian (aLG) laser beams. The beams have been derived via a complex-valued shift of conventional LG beams in the Cartesian plane. While propagating in a uniform medium, the first bright ring of the aLG beam becomes less asymmetric and the energy is redistributed toward peripheral diffraction rings. The projection of the orbital angular momentum (OAM) onto the optical axis is calculated. The OAM is shown to grow quadratically with increasing asymmetry parameter of the aLG beam, which equals the ratio of the shift to the waist radius. Conditions for the OAM becoming equal to the topological charge have been derived. For aLG beams with zero radial index, we have deduced an expression to define the intensity maximum coordinates and shown the crescent-shaped intensity pattern to rotate during propagation. Results of the experimental generation and rotation of aLG beams agree well with theoretical predictions.

  12. Research on reasonable side and mid-span ratio of railway long-span continuous beam-arch bridge%大跨度铁路连续梁拱组合桥的合理边中跨比研究

    Institute of Scientific and Technical Information of China (English)

    戴公连; 唐立新; 汪禹

    2015-01-01

    为了解边中跨比对大跨度铁路连续梁拱组合桥受力特性的影响,对目前大跨度铁路梁拱组合桥的边中跨比进行统计,并以兰渝线某(82+172+82)m 连续梁拱组合桥为工程背景,分析边中跨比对该桥内力、变形、支反力、稳定性等方面影响。研究结果表明:大跨度铁路连续梁拱组合桥的合理边中跨比取值为0.46~0.51;边中跨比取值较小时,对结构受力和变形有利,但边支座负反力的出现限制其值应大于0.43;边中跨比的取值对该桥基频和结构稳定性影响较小,随边中跨比由0.447增加到0.506,该桥的稳定安全系数仅增大7.6%。%Span ratio is one of the important design parameters in continuous beam -arch bridge,which directly affects the structural stress reasonably.In order to learn the effects of span ratio on the structural force of railway continuous beam -arch bridge,statistics of span ratio in the current long -span railway beam -arch bridges was analyzed.Taking an (82 +172 +82)m long -span continuous beam -arch bridge on the Lanzhou -Chongqing railway as an example,the effects of span ratio on its internal force,displacement,support reaction,stability and so on were analyzed.The analysis results show that the span ratio of long -span railway continuous beam -arch bridge varies from 0.46 to 0.51.Small span ratio is in favor of structural stress and deformation,but the e-mergence of negative support reaction limits its value should be greater than 0.43.While the contribution of span ratio to natural frequency and structural stability is small.Moreover,it is found that the value of stability factors only increased 7.6% with the span ratio increasing from 0.447 to 0.506.

  13. Plan view TEM sample preparation using the focused ion beam lift-out technique

    International Nuclear Information System (INIS)

    Localized plan view TEM samples have been prepared from silicon semiconductor wafers using the focused ion beam lift-out technique. Two different methods of sample preparation before FIB machining were found to be successful: mounting cleaved samples sandwiched together or adding silver paint and cleaving through paint and samples. The plan view technique offers site specific TEM capability from a horizontal section rather than a vertical cross section. The sections can be taken from any layer and can be angled if desired. Results have been obtained from metal layers in a semiconductor device structure. TEM micrographs of tungsten plug arrays show non-uniform barrier layer coverage and tungsten grain size across the via. Hundreds of plugs have been cut through in one sample, thereby offering statistical as well as specific structural information. Metal and polysilicon lines have been examined for grain size and uniformity in a single micrograph. Plan view samples from continuous metal layers can also be made

  14. Intrinsic flood-field uniformity evaluation

    International Nuclear Information System (INIS)

    The quality assurance program in a Nuclear Medicine Department pretends to minimize errors and artifacts that cover all aspects of clinical practice. The intrinsic flood-field uniformity is one of the quality control procedures to evaluate the response of a gamma camera to a spatially uniform flux of an incident gamma radiation over the field of view. The purpose of this study is to test our gamma cameras, by recording the obtained results of the integral and differential uniformity in order to generate a data base which is going to be our reference benchmark to evaluate the performance of the systems in the future. At the beginning we performed an evaluation of our acquisition protocol which implies the variation of the acquired counts, the energy window width and its placement. After that, we analyzed the recording data, creating plots which show the performance of the systems. As a result using an energy window placed at 140 keV at 20%, with matrix size of 512 x 512, acquiring 15 million counts and the source activity close to 700 μC; we obtained good images and both uniformities are within the manufacture's requirements, however, increasing the number of acquired counts, images are much better and an improvement in the evaluated parameters can be seen. The performance evaluation, of the three gamma cameras, was taken into account for approximately 240 days, showing an integral uniformity range of 1.04 - 3.5 % and the range for differential uniformity varies from 0.88 up to 2.7 %. We conclude that the gamma cameras were working well, we do not need to vary our acquisition protocol because it is good to evaluate these figures; also other factors affecting the quality of the images are radioactive waste material not very well shielded and temperature room variations, especially at the beginning of our workday. (author)

  15. Beam Instabilities

    CERN Document Server

    Rumolo, G

    2014-01-01

    When a beam propagates in an accelerator, it interacts with both the external fields and the self-generated electromagnetic fields. If the latter are strong enough, the interplay between them and a perturbation in the beam distribution function can lead to an enhancement of the initial perturbation, resulting in what we call a beam instability. This unstable motion can be controlled with a feedback system, if available, or it grows, causing beam degradation and loss. Beam instabilities in particle accelerators have been studied and analysed in detail since the late 1950s. The subject owes its relevance to the fact that the onset of instabilities usually determines the performance of an accelerator. Understanding and suppressing the underlying sources and mechanisms is therefore the key to overcoming intensity limitations, thereby pushing forward the performance reach of a machine.

  16. The refined theory of transversely isotropic piezoelectric rectangular beams

    Institute of Scientific and Technical Information of China (English)

    GAO; Yang; WANG; Minzhong

    2006-01-01

    The problem of deducing one-dimensional theory from two-dimensional theory for a transversely isotropic piezoelectric rectangular beam is investigated. Based on the piezoelasticity theory, the refined theory of piezoelectric beams is derived by using the general solution of transversely isotropic piezoelasticity and Lur'e method without ad hoc assumptions. Based on the refined theory of piezoelectric beams, the exact equations for the beams without transverse surface loadings are derived, which consist of two governing differential equations: the fourth-order equation and the transcendental equation. The approximate equations for the beams under transverse loadings are derived directly from the refined beam theory. As a special case, the governing differential equations for transversely isotropic elastic beams are obtained from the corresponding equations of piezoelectric beams. To illustrate the application of the beam theory developed, a uniformly loaded and simply supported piezoelectric beam is examined.

  17. Uniform wire segmentation algorithm of distributed interconnects

    Institute of Scientific and Technical Information of China (English)

    Yin Guoli; Lin Zhenghui

    2007-01-01

    A uniform wire segmentation algorithm for performance optimization of distributed RLC interconnects was proposed in this paper. The optimal wire length for identical segments and buffer size for buffer insertion are obtained through computation and derivation, based on a 2-pole approximation model of distributed RLC interconnect. For typical inductance value and long wires under 180nm technology, experiments show that the uniform wire segmentation technique proposed in the paper can reduce delay by about 27% ~ 56% , while requires 34%~69% less total buffer usage and thus 29% to 58% less power consumption. It is suitable for long RLC interconnect performance optimization.

  18. New approaches for boosting to uniformity

    International Nuclear Information System (INIS)

    The use of multivariate classifiers has become commonplace in particle physics. To enhance the performance, a series of classifiers is typically trained; this is a technique known as boosting. This paper explores several novel boosting methods that have been designed to produce a uniform selection efficiency in a chosen multivariate space. Such algorithms have a wide range of applications in particle physics, from producing uniform signal selection efficiency across a Dalitz-plot to avoiding the creation of false signal peaks in an invariant mass distribution when searching for new particles

  19. DIE VROU IN UNIFORM: STANDPUNTE EN BESKOUINGE

    Directory of Open Access Journals (Sweden)

    E.M. Meyers

    2012-02-01

    Full Text Available The increasing application of women in uniform is inviting considerable discussion in current literature. The position of the woman in uniform is at present placed under much closer scrutiny, as a result of various factors, such as the rise of feminism, revolutionary social changes, the entrance of women into the different occupational sectors and the principle of the equality of mankind (egalitarianism. A wide spectrum of aspects connected with the position of women in a military situation is analysed, and the divergent points of view maintained by different communities on this subject are taken into account.

  20. Bifurcations of Periodic Orbits and Uniform Approximations

    CERN Document Server

    Schomerus, H; Schomerus, Henning; Sieber, Martin

    1997-01-01

    We derive uniform approximations for contributions to Gutzwiller's periodic-orbit sum for the spectral density which are valid close to bifurcations of periodic orbits in systems with mixed phase space. There, orbits lie close together and give collective contributions, while the individual contributions of Gutzwiller's type would diverge at the bifurcation. New results for the tangent, the period doubling and the period tripling bifurcation are given. They are obtained by going beyond the local approximation and including higher order terms in the normal form of the action. The uniform approximations obtained are tested on the kicked top and are found to be in excellent agreement with exact quantum results.

  1. Uniform color space is not homogeneous

    Science.gov (United States)

    Kuehni, Rolf G.

    2002-06-01

    Historical data of chroma scaling and hue scaling are compared and evidence is shown that we do not have a reliable basis in either case. Several data sets indicate explicitly or implicitly that the number of constant sized hue differences between unique hues as well as in the quadrants of the a*, b* diagram differs making what is commonly regarded as uniform color space inhomogeneous. This problem is also shown to affect the OSA-UCS space. A Euclidean uniform psychological or psychophysical color space appears to be impossible.

  2. 47 CFR 76.1608 - System technical integration requiring uniform election of must-carry or retransmission consent...

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false System technical integration requiring uniform... COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Notices § 76.1608 System technical integration requiring uniform election of must-carry or...

  3. Development of 2D particle-in-cell code to simulate high current, low energy beam in a beam transport system

    Indian Academy of Sciences (India)

    S C L Srivastava; S V L S Rao; P Singh

    2007-10-01

    A code for 2D space-charge dominated beam dynamics study in beam transport lines is developed. The code is used for particle-in-cell (PIC) simulation of -uniform beam in a channel containing solenoids and drift space. It can also simulate a transport line where quadrupoles are used for focusing the beam. Numerical techniques as well as the results of beam dynamics studies are presented in the paper.

  4. Analysis of warping deformation modes using higher order ANCF beam element

    Science.gov (United States)

    Orzechowski, Grzegorz; Shabana, Ahmed A.

    2016-02-01

    Most classical beam theories assume that the beam cross section remains a rigid surface under an arbitrary loading condition. However, in the absolute nodal coordinate formulation (ANCF) continuum-based beams, this assumption can be relaxed allowing for capturing deformation modes that couple the cross-section deformation and beam bending, torsion, and/or elongation. The deformation modes captured by ANCF finite elements depend on the interpolating polynomials used. The most widely used spatial ANCF beam element employs linear approximation in the transverse direction, thereby restricting the cross section deformation and leading to locking problems. The objective of this investigation is to examine the behavior of a higher order ANCF beam element that includes quadratic interpolation in the transverse directions. This higher order element allows capturing warping and non-uniform stretching distribution. Furthermore, this higher order element allows for increasing the degree of continuity at the element interface. It is shown in this paper that the higher order ANCF beam element can be used effectively to capture warping and eliminate Poisson locking that characterizes lower order ANCF finite elements. It is also shown that increasing the degree of continuity requires a special attention in order to have acceptable results. Because higher order elements can be more computationally expensive than the lower order elements, the use of reduced integration for evaluating the stress forces and the use of explicit and implicit numerical integrations to solve the nonlinear dynamic equations of motion are investigated in this paper. It is shown that the use of some of these integration methods can be very effective in reducing the CPU time without adversely affecting the solution accuracy.

  5. 1D non-uniform dose delivery by a single dynamic absorber

    International Nuclear Information System (INIS)

    A new technique for 1D non-uniform dose delivery has been recently proposed, using a single computer-controlled dynamic absorber, which is driven within the beam during irradiation. Analytical-iterative and convolution algorithms have been developed in order to optimize the movement of the absorber in creating wished beam modulations. The technique has been demonstrated to be suitable for many applications in the fields of dynamic wedging, tissue-deficit compensation and, in some cases, conformal therapy by non-uniform dose delivery. A first non-focused prototype has been shown to be able to reproduce a number of modulated beams with an acceptable accuracy (Phys.Med. Biol. 40: 221-240, 1995). A new focused prototype has been carried out at our Institute and it is under investigation: preliminary tests (by diodes array and film dosimetry) confirm the wide possibilities of clinical application. The apparatus, which can be inserted in the tray holder of our Clinac Varian 6/100, is connected through a mechanical transmission system to a computer where absorber's speed profiles (corresponding to wished fluence profiles) are stored. The operator can recall the wished profile and move the absorber in the due way, when the irradiation starts. The single-absorber dynamic modulation technique cannot modulate the beam fluence in any way one wishes, due to the physical constraint that the absorber can stay in the irradiation field for a time not larger than the total irradiation time: however it can create a large number of dynamically modulated beams clinically interesting. For this reason it should be considered as a valid 'low-cost' technique for dynamic beam modulation (also on Linacs which do not have complex computer-controlled options for non-uniform dose delivery such as dynamic collimators and multi leaves)

  6. New continuity estimates of geometric sums

    Directory of Open Access Journals (Sweden)

    Evgueni Gordienko

    2002-01-01

    Full Text Available The paper deals with sums of a random number of independent and identically distributed random variables. More specifically, we compare two such sums, which differ from each other in the distributions of their summands. New upper bounds (inequalities for the uniform distance between distributions of sums are established. The right-hand sides of these inequalities are expressed in terms of Zolotarev's and the uniform distances between the distributions of summands. Such a feature makes it possible to consider these inequalities as continuity estimates and to apply them to the study of the stability (continuity of various applied stochastic models involving geometric sums and their generalizations.

  7. Intense electron beam propagation into vacuum

    International Nuclear Information System (INIS)

    The authors have performed experimental and theoretical studies of the propagation of an intense electron beam (1 MeV, 27 kA, 30 ns) into a long evacuated drift cube. In one case the beam propagates because an applied axial magnetic field immerses the entire system. In the second case a localized source of ions for charge neutralization enables the beam is propagate. In the case of a magnetically confined beam, experimental results for current propagation as a function of uniform applied magnetic field (0-1.2 Tesla) are presented for various drift tube diameters, cathode geometries, and anode aperture sizes. An analytic model of laminar beam flow is presented which predicts the space charge limited current of a solid intense relativistic electron beam (IREB) propagating in a grounded drift tube as a function of tube and diode sizes and applied magnetic field. Comparisons between the experimental and theoretical results are discussed

  8. 考虑剪滞剪切效应的复合材料薄壁箱型连续梁理论分析%Theoretical Analysis of Composite Thin-walled Box Continuous Beam Considering Vertical Shear Deformation and Shear Lag Effect

    Institute of Scientific and Technical Information of China (English)

    韩博; 吴亚平

    2011-01-01

    In this paper, four-degree parabola of cubic term is adopted to simulate axial displacement of box beam flange, considering vertical shear deformation and shear lag effect, differential equations of symmetrically laminated composite box beam under symmetrical bending have been deduced firstly, and displacement differenee functions in two-equal-span continuous beam under concentrated load P applied at mid-span respectively have been also deduced. Finally, based on a concrete example of composite thin walled box continuous beam,comparing the theoretical results of this paper with the result of the ANSYS finite element simulation and experiment results, it is demonstrated clearly that this method agrees well with the ANSYS finite element and experiment, so the results are reliableand accurate.%以含三次项的四次抛物线作为箱梁翼缘板的纵向位移函数,推导出了考虑横向剪切变形及剪力滞后效应时的双轴对称铺设的复合材料层合箱梁在对称弯曲条件下的控制微分方程,并推导出了两等跨连续梁分别在跨中受一集中力P的位移差函数,最后结合具体的复合材料箱型连续梁实例,将本文理论推导的结果与ANSYS结果以及实验结果进行了对比,结果表明,理论推导的结果与ANSYS结果和实验结果吻合较好,其结果是正确可靠的.

  9. Magnetostatics of the uniformly polarized torus

    DEFF Research Database (Denmark)

    Beleggia, Marco; De Graef, Marc; Millev, Yonko

    2009-01-01

    We provide an exhaustive description of the magnetostatics of the uniformly polarized torus and its derivative self-intersecting (spindle) shapes. In the process, two complementary approaches have been implemented, position-space analysis of the Laplace equation with inhomogeneous boundary...

  10. Uniform Or Free Dress Code in Schools

    OpenAIRE

    Erkan, Doç. Dr. Serdar

    2003-01-01

    This article attempts to synthesize opinions, results of experiments and research about school dress code policies. Synthesis suggests that there are positive as well as negative effects and consequences of mandatory school uniform policy. Pilot projects should be implemented and social and cultural effects should be examined prior to any decision regarding changes in current dress codes and policies.

  11. School Uniforms in Urban Public High Schools

    Science.gov (United States)

    Draa, Virginia Ann Bendel

    2005-01-01

    The purpose of this study was to determine whether or not the implementation of a mandatory uniform policy in urban public high schools improved school performance measures at the building level for rates of attendance, graduation, academic proficiency, and student conduct as measured by rates of suspensions and expulsions. Sixty-four secondary…

  12. UNIFORM QUASINILPOTENCY: DEFINITIONS, CONDITIONS, EXAMPLES OF APPLICATIONS

    OpenAIRE

    Sumin, Vladimir

    2010-01-01

    Definition of uniform quasinilpotent family of the operators and definition of superuniform quasinilpotent family of the operators are introduced. Corresponding conditions for functional operators are formulated. Applications of these definititions and conditions in the theory of controllable Volterra functional-operator equations are discussed. Financial support of Russian Fundamental Researches Fund (project 07-01-00495), analytical aimed departmental program "Development of Scientific Pote...

  13. School Uniform Revisited: Procedure, Pressure and Equality

    Science.gov (United States)

    Carney, Damian; Sinclair, Adele

    2006-01-01

    The House of Lords' decision in "R. (on the application of Begum) v. The Headteacher and Governors of Denbigh High School" considered whether a particular school uniform policy infringed a student's right to manifest her religion under Article 9. This paper analyses the content of this decision, and explores how schools should approach the issue…

  14. Product of n independent uniform random variables

    OpenAIRE

    Dettmann, Carl P.; Georgiou, Orestis

    2009-01-01

    Abstract We give an alternative proof of a useful formula for calculating the probability density function of the product of n uniform, independently and identically distributed random variables. Ishihara (2002, in Japanese) proves the result by induction; here we use Fourier analysis and contour integral methods which provide a more intuitive explanation of how the convolution theorem acts in this case. correspondance: Corresponding author. ...

  15. Mandatory School Uniforms and Freedom of Expression

    Science.gov (United States)

    Vopat, Mark C.

    2010-01-01

    On 10 December 2007 the Akron City School Board--following the precedent set by many school systems across the United States and the world--instituted a policy of mandatory school uniforms for all students in grades K-8. The measure was met with mixed reviews. While many parents supported the measure, a small group of parents from a selective,…

  16. Dynamic Uniform Scaling for Multiobjective Genetic Algorithms

    DEFF Research Database (Denmark)

    Pedersen, Gerulf; Goldberg, D.E.

    2004-01-01

    Before Multiobjective Evolutionary Algorithms (MOEAs) can be used as a widespread tool for solving arbitrary real world problems there are some salient issues which require further investigation. One of these issues is how a uniform distribution of solutions along the Pareto non-dominated front c...

  17. Uniform Convergence of Multivariate Spectral Density Estimates

    OpenAIRE

    Wu, Wei Biao; Zaffaroni, Paolo

    2015-01-01

    We consider uniform moment convergence of lag-window spectral density estimates for univariate and multivariate stationary processes. Optimal rates of convergence are obtained under mild and easily verifiable conditions. Our theory complements earlier results which primarily concern weak or in-probability convergence.

  18. UMAPRM: Uniformly sampling the medial axis

    KAUST Repository

    Yeh, Hsin-Yi Cindy

    2014-05-01

    © 2014 IEEE. Maintaining clearance, or distance from obstacles, is a vital component of successful motion planning algorithms. Maintaining high clearance often creates safer paths for robots. Contemporary sampling-based planning algorithms That utilize The medial axis, or The set of all points equidistant To Two or more obstacles, produce higher clearance paths. However, They are biased heavily Toward certain portions of The medial axis, sometimes ignoring parts critical To planning, e.g., specific Types of narrow passages. We introduce Uniform Medial Axis Probabilistic RoadMap (UMAPRM), a novel planning variant That generates samples uniformly on The medial axis of The free portion of Cspace. We Theoretically analyze The distribution generated by UMAPRM and show its uniformity. Our results show That UMAPRM\\'s distribution of samples along The medial axis is not only uniform but also preferable To other medial axis samplers in certain planning problems. We demonstrate That UMAPRM has negligible computational overhead over other sampling Techniques and can solve problems The others could not, e.g., a bug Trap. Finally, we demonstrate UMAPRM successfully generates higher clearance paths in The examples.

  19. Uniform reflective films deposited on large surfaces

    Science.gov (United States)

    1966-01-01

    Specially designed baffle which intercepts varying amounts of the vapor stream from an evaporant source, vacuum deposits films of uniform thickness on large substrates, using a single small area evaporation source. A mirror coated by this method will have a reflectance as high as 82 percent at 1216 angstroms with a variation of only plus/minus 2 percent over the surface.

  20. ATA probe beam experiment

    International Nuclear Information System (INIS)

    The philosophy of these tests is to measure the motion of a low current, small diameter electron beam in the accelerator before running high current. By using low current, we can study particle motion in the applied fields without any extra complications associated with the self-forces of high currents. With the steering magnets off, we have measured the transverse drift of the probe beam. Also, we have used the probe beam to optimize the current in the steering magnets to compensate for the drift. There have been concurrent efforts to locate the source of the error field which is presumed to cause the drift. So far, the source has not been established but the search is continuing

  1. Acoustic Tractor Beam

    Science.gov (United States)

    Démoré, Christine E. M.; Dahl, Patrick M.; Yang, Zhengyi; Glynne-Jones, Peter; Melzer, Andreas; Cochran, Sandy; MacDonald, Michael P.; Spalding, Gabriel C.

    2014-05-01

    Negative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (>1 cm) to demonstrate the negative radiation forces and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to nonconservative forces, produced by redirection of a momentum flux from the angled sides of a target and not by conservative forces from a potential energy gradient. Use of a simple acoustic setup provides an easily understood illustration of the negative radiation pressure concept for tractor beams and demonstrates continuous attraction towards the source, against a net momentum flux in the system.

  2. Low voltage, hermetically sealed electron beam accelerator for industrial applications

    International Nuclear Information System (INIS)

    Three types of hermetically sealed, low voltage electron beam accelerators and novel solid state power supply/control systems have been developed by Advanced Electron Beams. These accelerators produce uniform, unscanned electron beams through the unique management of the thermionic emitter profile and vacuum body shape. The power density of the accelerators range from 0.02 to 0.2 kW per square centimetre with accelerating voltages ranging from 60 to 150 kV and extracted electron currents of 1 to 30 mA. A wide variety of in-process-line industrial applications have been implemented and continue to be developed for these accelerators including: curing of high density and/or high opacity thin films; cross-linking or chain scission of thermoplastic films; pre-fill disinfestation of food and beverage packaging; sterilization of medical devices and pharmaceutical container surfaces; and the active treatment of air streams for pollution abatement and bioburden remediation. This paper will describe the design of the three emitters and the methods of application implementation. (author)

  3. Perceptual uniformity of commonly used color spaces

    Science.gov (United States)

    Avanaki, Ali; Espig, Kathryn; Kimpe, Tom; Xthona, Albert; Marchessoux, Cedric; Rostang, Johan; Piepers, Bastian

    2014-03-01

    Use of color images in medical imaging has increased significantly the last few years. Color information is essential for applications such as ophthalmology, dermatology and clinical photography. Use of color at least brings benefits for other applications such as endoscopy, laparoscopy and digital pathology. Remarkably, as of today, there is no agreed standard on how color information needs to be visualized for medical applications. This lack of standardization results in large variability of how color images are visualized and it makes quality assurance a challenge. For this reason FDA and ICC recently organized a joint summit on color in medical imaging (CMI). At this summit, one of the suggestions was that modalities such as digital pathology could benefit from using a perceptually uniform color space (T. Kimpe, "Color Behavior of Medical Displays," CMI presentation, May 2013). Perceptually uniform spaces have already been used for many years in the radiology community where the DICOM GSDF standard provides linearity in luminance but not in color behavior. In this paper we quantify perceptual uniformity, using CIE's ΔE2000 as a color distance metric, of several color spaces that are typically used for medical applications. We applied our method to theoretical color spaces Gamma 1.8, 2.0, & 2.2, standard sRGB, and DICOM (correction LUT for gray applied to all primaries). In addition, we also measured color spaces (i.e., native behavior) of a high-end medical display (Barco Coronis Fusion 6MP DL, MDCC-6130), and a consumer display (Dell 1907FP). Our results indicate that sRGB & the native color space on the Barco Coronis Fusion exhibit the least non-uniformity within their group. However, the remaining degree of perceptual non-uniformity is still significant and there is room for improvement.

  4. Non-Linear Beam Transport System for the LENS 7 MeV Proton Beam

    CERN Document Server

    Jones, William P; Derenchuk, Vladimir Peter; Rinckel, Thomas; Solberg, Keith

    2005-01-01

    A beam transport system has been designed to carry a high-intensity low-emittance proton beam from the exit of the RFQ-DTL acceleration system of the Indiana University Low Energy Neutron System (LENS)* to the neutron production target. The goal of the design was to provide a beam of uniform density over a 3cm by 3cm area at the target. Two octupole magnets** are employed in the beam line to provide the necessary beam phase space manipulations to achieve this goal. First order calculations were done using TRANSPORT and second order calculations have been performed using TURTLE. Second order simulations have been done using both a Gaussian beam distribution and a particle set generated by calculations of beam transport through the RFQ-DTL using PARMILA. Comparison of the design characteristics with initial measurements from the LENS commissioning process will be made.

  5. High-power continuous-wave mid-infrared radiation generated by difference frequency mixing of diode-laser-seeded fiber amplifiers and its application to dual-beam spectroscopy

    Science.gov (United States)

    Lancaster, D. G.; Richter, D.; Curl, R. F.; Tittel, F. K.; Goldberg, L.; Koplow, J.

    1999-01-01

    We report the generation of up to 0.7 mW of narrow-linewidth (laser-seeded 0.6-W Er/Yb fiber amplifier in periodically poled LiNbO3. A conversion efficiency of 0.09%/W (0.47 mWW-2 cm-1) was achieved. A room-air CH4 spectrum acquired with a compact 80-m multipass cell and a dual-beam spectroscopic configuration indicates an absorption sensitivity of +/-2.8 x 10(-5) (+/-1 sigma), corresponding to a sub-parts-in-10(9) (ppb) CH4 sensitivity (0.8 ppb).

  6. Effect of variable viscosity on laminar convection flow of an electrically conducting fluid in uniform magnetic field

    OpenAIRE

    Chakraborty S; Borkakati A.K.

    2002-01-01

    The flow of a viscous incompressible electrically conducting fluid on a continuous moving flat plate in presence of uniform transverse magnetic field, is studied. The flat plate which is continuously moving in its own plane with a constant speed is considered to be isothermally heated. Assuming the fluid viscosity as an inverse linear function of temperature, the nature of fluid velocity and temperature in presence of uniform magnetic field are shown for changing viscosity parameter at differ...

  7. Molecular beams

    International Nuclear Information System (INIS)

    This book is a timeless and rather complete theoretical and experimental treatment of electric and magnetic resonance molecular-beam experiments for studying the radio frequency spectra of atoms and molecules. The theory of interactions of the nucleus with atomic and molecular fields is extensively presented. Measurements of atomic and nuclear magnetic moments, electric multipole moments, and atomic fine and hyperfine structure are detailed. Useful but somewhat outdated chapters on gas kinetics, molecular beam design, and experimental techniques are also included

  8. Blind Direction-of-Arrival Estimation with Uniform Circular Array in Presence of Mutual Coupling

    OpenAIRE

    Song Liu; Lisheng Yang; Shizhong Yang; Qingping Jiang; Haowei Wu

    2016-01-01

    A blind direction-of-arrival (DOA) estimation algorithm based on the estimation of signal parameters via rotational invariance techniques (ESPRIT) is proposed for a uniform circular array (UCA) when strong electromagnetic mutual coupling is present. First, an updated UCA model with mutual coupling in a discrete Fourier transform (DFT) beam space is deduced, and the new manifold matrix is equal to the product of a centrosymmetric diagonal matrix and a Vandermonde-structure matrix. Then we carr...

  9. A progressive reduce tension method to fabricate Bradbury-Nielsen gates with uniform tension

    CERN Document Server

    Kai, Ni; Zhou, Yu

    2015-01-01

    Bradbury-Nielsen gates (BNG) which consist of two interleaved and electrically isolated sets of wires can be used to modulate the beams of charged particles, particularly ion beams in mass spectrometry and ion mobility spectrometry. The wires of BNG with uniform tension is critical to make sure the BNG work reliable and robust. In our previous work, we have analyzed the problem of wires tension non-uniform that exists in the traditional sequentially winding methods when the metal wire's elastic modulus is much larger than insulations substrate's and developed a template-based transfer method to solve this problem. In this study, we proposed a progressive reduce tension method which does not need template to fabricate BNG with uniform tension. First input the initial parameters to calculate the final progressive reduce tension sequence (FA(i)) through program; then sequentially adjust the weight set according to FA(i) to construct a BNG with uniform tension wires through a home-built device. Wires tension non-...

  10. Stability Analysis of Nonuniform Rectangular Beams Using Homotopy Perturbation Method

    Directory of Open Access Journals (Sweden)

    Seval Pinarbasi

    2012-01-01

    Full Text Available The design of slender beams, that is, beams with large laterally unsupported lengths, is commonly controlled by stability limit states. Beam buckling, also called “lateral torsional buckling,” is different from column buckling in that a beam not only displaces laterally but also twists about its axis during buckling. The coupling between twist and lateral displacement makes stability analysis of beams more complex than that of columns. For this reason, most of the analytical studies in the literature on beam stability are concentrated on simple cases: uniform beams with ideal boundary conditions and simple loadings. This paper shows that complex beam stability problems, such as lateral torsional buckling of rectangular beams with variable cross-sections, can successfully be solved using homotopy perturbation method (HPM.

  11. OMEGA: a 24 beam uv irradiation facility

    International Nuclear Information System (INIS)

    We report the recent completion of the uv upconversion (351 nm) of all 24 beams of the OMEGA laser which provides a unique short wavelength symmetrical irradiation facility for direct drive laser fusion experiments. Details of the characterization of illumination uniformity and initial implosion experiments will be described

  12. Dynamic thermopower in uniform unipolar semiconductor

    Science.gov (United States)

    Volovichev, Igor

    2016-03-01

    A dynamic thermoelectric effect in uniform unipolar semiconductors is predicted. It is shown that a "traveling wave"-shaped temperature distribution generates an electric current in a uniform semiconductor closed circuit. The dependence of the short-circuit current on the semiconductor parameters, as well as the amplitude, the wavelength, and the temperature wave velocity, has been studied theoretically. It is demonstrated that the electric current generally has both AC and DC components, while the AC component vanishes in the quasi-neutrality. The conditions wherein the magnitude of the thermoelectric current is independent of the semiconductor Seebeck coefficient are deduced. It is shown that there are optimal values for the temperature wavelength and its velocity at which the predicted dynamic thermoelectric effect is the greatest. Possible practical applications of the predicted effect are discussed.

  13. Influence on discharge uniformity of electrodes configuration

    CERN Document Server

    Zheng Jian; Sui Zhan; Lu Jing Ping; Zheng Kui Xing; Zhang Xiong Jun; Dong Yun; Feng Bin

    2002-01-01

    Large area glow discharge plasma that is transparent and highly conductive can be used as electrodes in Pockels cell to extend the switch aperture. To investigate this technology, a glow discharging chamber with a clear aperture of 5 cm x 5 cm was constructed, and hollow cathode, button cathode, pin cathode, bar cathode and bar anode were designed and produced. Using CCD imaging system, the discharging uniformity of different cathodes was tested with bar anode and under the different pressure pre-ionization voltage and main discharging voltage. A uniform plasma can be obtained with a hollow cathode when the pre-ionization voltage is about 700 V, the pressure is about 30 Pa, and the main discharging voltage is about 4 kV, which can be used for the plasma electrode of Pockels cell

  14. Strong shock in the uniformly expanding medium

    CERN Document Server

    Bisnovatyi-Kogan, G S

    2014-01-01

    Propagation of the strong shock in the flat expanding Friedman universe is investigated using methods of dimension and similarity. Exact analytic solution of self-similar equations is obtained, determining dependences of the radius and velocity of the shock wave on time and radius. It is obtained, that in the expanding medium the velocity of shock decreases as $\\sim t^{-1/5}$, what is slower than the shock velocity in the static uniform medium $\\sim t^{-3/5}$. The radius of the shock wave in the expanding self-gravitating medium increases $\\sim t^{4/5}$, more rapidly than the shock wave radius in the uniform non-gravitating medium $\\sim t^{2/5}$. So, the shock propagates in the direction of decreasing density with larger speed, that in the static medium, due to accelerating action of the decreasing density, even in the presence of a self-gravitation.

  15. Uniform Algebras Over Complete Valued Fields

    CERN Document Server

    Mason, Jonathan W

    2012-01-01

    UNIFORM algebras have been extensively investigated because of their importance in the theory of uniform approximation and as examples of complex Banach algebras. An interesting question is whether analogous algebras exist when a complete valued field other than the complex numbers is used as the underlying field of the algebra. In the Archimedean setting, this generalisation is given by the theory of real function algebras introduced by S. H. Kulkarni and B. V. Limaye in the 1980s. This thesis establishes a broader theory accommodating any complete valued field as the underlying field by involving Galois automorphisms and using non-Archimedean analysis. The approach taken keeps close to the original definitions from the Archimedean setting. Basic function algebras are defined and generalise real function algebras to all complete valued fields. Several examples are provided. Each basic function algebra is shown to have a lattice of basic extensions related to the field structure. In the non-Archimedean settin...

  16. 48 CFR 14.201-1 - Uniform contract format.

    Science.gov (United States)

    2010-10-01

    ... uniform contract format applies shall include Parts I, II, III, and IV. If any section of the uniform... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Uniform contract format... CONTRACTING METHODS AND CONTRACT TYPES SEALED BIDDING Solicitation of Bids 14.201-1 Uniform contract...

  17. Production of ion micro-beams

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Yasuyuki; Isoya, Akira; Arakawa, Kazuo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Tanaka, Ryuichi [Ion Beam Irradiation Service Limited Company, Takasaki, Gunma (Japan)

    2001-02-01

    This is a short summary on the test fabrication and performance testing. Here micro-beams are understood as beams in diameter smaller than 0.01 {mu} m. We had made a choice of the combination, of the focusing action with a single hole lens, and of the focusing and acceleration actions with a uniform electrostatic field between the electrodes. Measurements has been repeated of the beam radius with a moving knifedge. The spatial resolution now reaches 0.05 {mu} m. (M. Tanaka)

  18. The use of uniform flood field for relative dosimetry using the amorphous-silicon epid

    International Nuclear Information System (INIS)

    Full text: The amorphous silicon electronic portal imaging device (a-Si EPID) has been investigated by several researchers as a means of performing relative and absolute dosimetry measurements, in particular dosimetric verification of IMRT fields. It has been suggested that a uniform (flat) flood field calibration plays an important role in subsequent image acquisition for ensuring accurate dose response. The aims of this paper are (i) to determine the conditions required to obtain a uniform flood field, and (ii) to investigate the dosimetric response of the EPID when uniform and non-uniform flood field calibrations are applied, in the context of a comparison between EPID acquired IMRT fields, radiographic film and the treatment planning system. Flood-field (FF) calibrations were performed on the a-Si EPID using 0 cm, 2 cm, 5 cm, 7 cm and 10 cm of solid water build-up material placed directly onto the vinyl protective cover of the EPID. Source-EPID distance of 155 cm and 105 cm were used for these calibrations. The FF calibration was also performed by placing 0 cm, 1 cm, 2 cm, 3 cm and 4 cm solid water build-up material close to the gantry head in the applicator holder. After each FF calibration an open field test image was acquired with no build-up on the EPID. Images of wedged fields with differing FF calibrations were also acquired. A 45 degree physical wedge was used on a Varian 600C linac and a segmental MLC step wedge used on a 2100C linac. Images of open and wedged fields were acquired under similar conditions using XOmat-V radiographic film. Relative dosimetric scans were obtained in a Wellhofer water tank using a PTW IClO ionisation chamber. In addition, a segmental MLC IMRT field was delivered and a continuous frame-averaging mode image of the IMRT field was acquired. The open-field and IMRT images therefore, had the previous FF calibration applied. In addition, the fluence map of the field was acquired from the treatment planning system. Inplane and

  19. A uniform information system of municipal roads

    OpenAIRE

    Zajamšek, Franc

    2013-01-01

    The field of information systems of municipal roads is examined in the master’s thesis. The rules managing this area, existing information systems and databases are presented and analysed. Business processes (planning, management, protection, maintenance, investment, control, execution of works ...) which are taking place in this field, are analysed and specified. Design plan of the uniform information system of municipal roads, consists of diagrams and processes descriptions. The sy...

  20. Weighted averages, uniform distribution, and strict ergodicity

    International Nuclear Information System (INIS)

    A circle of problems related to the application of the Riesz and Voronoi summation methods in ergodic theory, number theory, and probability theory is considered. The first digit paradox is discussed, strengthenings of the classical result of Weyl on the uniform distribution of the fractional parts of the values of a polynomial are indicated, and the possibility of sharpening the Birkhoff-Khinchin ergodic theorem is considered. In conclusion, some unsolved problems are listed

  1. Uniform Convergence in B-Duals

    Directory of Open Access Journals (Sweden)

    Charles Swartz

    2013-09-01

    Full Text Available Let E be a vector valued sequence space with â-dual Åâã. We consider sufficient conditions on E for the series in a pointwise bounded subset of Åâã to be uniformly convergent over certain subsets of E. The conditions involve gliding hump assumptions on the multiplier space E. Applications to matrix mappings between vector valued sequence spaces are given.

  2. Sequential Testing with Uniformly Distributed Size

    OpenAIRE

    Stanislav Anatolyev; Grigory Kosenok

    2011-01-01

    Sequential procedures of testing for structural stability do not provide enough guidance on the shape of boundaries that are used to decide on acceptance or rejection, requiring only that the overall size of the test is asymptotically controlled. We introduce and motivate a reasonable criterion for a shape of boundaries which requires that the test size be uniformly distributed over the testing period. Under this criterion, we numerically construct boundaries for most popular sequential tests...

  3. Dynamic Uniform Scaling for Multiobjective Genetic Algorithms

    DEFF Research Database (Denmark)

    Pedersen, Gerulf; Goldberg, David E.

    2004-01-01

    Before Multiobjective Evolutionary Algorithms (MOEAs) can be used as a widespread tool for solving arbitrary real world problems there are some salient issues which require further investigation. One of these issues is how a uniform distribution of solutions along the Pareto non-dominated front can......, the issue of obtaining a diverse set of solutions for badly scaled objective functions will be investigated and proposed solutions will be implemented using the NSGA-II algorithm....

  4. Uniform convergence to equilibrium for granular media

    CERN Document Server

    Bolley, François; Guillin, Arnaud

    2012-01-01

    We study the long time asymptotics of a nonlinear, nonlocal equation used in the modelling of granular media. We prove a uniform exponential convergence to equilibrium for degenerately convex and non convex interaction or confinement potentials, improving in particular results by J. A. Carrillo, R. J. McCann and C. Villani. The method is based on studying the dissipation of the Wasserstein distance between a solution and the steady state.

  5. Magnetic Propeller for Uniform Magnetic Field Levitation

    OpenAIRE

    Krinker, Mark; Bolonkin, Alexander

    2008-01-01

    Three new approaches to generating thrust in uniform magnetic fields are proposed. The first direction is based on employing Lorentz force acting on partial magnetically shielded 8-shaped loop with current in external magnetic field, whereby a net force rather than a torque origins. Another approach, called a Virtual Wire System, is based on creating a magnetic field having an energetic symmetry (a virtual wire), with further superposition of external field. The external field breaks the symm...

  6. High-power continuous-wave mid-infrared radiation generated by difference frequency mixing of diode-laser-seeded fiber amplifiers and its application to dual-beam spectroscopy

    Science.gov (United States)

    Lancaster, D. G.; Richter, D.; Curl, R. F.; Tittel, F. K.; Goldberg, L.; Koplow, J.

    1999-01-01

    We report the generation of up to 0.7 mW of narrow-linewidth (fiber amplifier and a 1.5-micrometers diode-laser-seeded 0.6-W Er/Yb fiber amplifier in periodically poled LiNbO3. A conversion efficiency of 0.09%/W (0.47 mWW-2 cm-1) was achieved. A room-air CH4 spectrum acquired with a compact 80-m multipass cell and a dual-beam spectroscopic configuration indicates an absorption sensitivity of +/-2.8 x 10(-5) (+/-1 sigma), corresponding to a sub-parts-in-10(9) (ppb) CH4 sensitivity (0.8 ppb).

  7. Beam emittance and beam disruption

    International Nuclear Information System (INIS)

    Beam disruption during the collision of intense relativistic bunches has been studied by R. Hollebeek. In the case of oppositely charged bunches, focussing effects occur causing a decrease in the effective bunch cross section, and thereby an increase of luminosity by an enhancement factor H. The term disruption derives from the fact that the beam emittance changes markedly during the collision. 1 ref., 1 fig., 1 tab

  8. Uniformity: The key to better inventory management

    International Nuclear Information System (INIS)

    The objective of this paper is to show how uniformity in describing parts and materials can be the key ingredient to more effective inventory management. Although most nuclear utilities have some type of computer system for maintenance management as well as materials tracking, few have a system to provide the various users with complete information about parts and material in stock. One of the industry's most perplexing problems is How do you know, and find, the item you need to repair a particular piece of equipment or component? In many instances it is easier to order a new one from the manufacturer rather than try to find it on-site, which can result in inaccurate usage records, over-stocking, frustration, and strain on cash flow. What is needed is a higher degree of uniformity within a station, and a utility, of catalog descriptions for parts and material that will satisfy all users-planners, craftsmen, warehouse personnel, and buyers. The results of attaining this uniformity are improved performance through searchability, duplicate stock avoidance, interchangeability, substitutability, and more accurate bills of material; economic benefits will also be noted

  9. The non-uniformity of fossil preservation.

    Science.gov (United States)

    Holland, Steven M

    2016-07-19

    The fossil record provides the primary source of data for calibrating the origin of clades. Although minimum ages of clades are given by the oldest preserved fossil, these underestimate the true age, which must be bracketed by probabilistic methods based on multiple fossil occurrences. Although most of these methods assume uniform preservation rates, this assumption is unsupported over geological timescales. On geologically long timescales (more than 10 Myr), the origin and cessation of sedimentary basins, and long-term variations in tectonic subsidence, eustatic sea level and sedimentation rate control the availability of depositional facies that preserve the environments in which species lived. The loss of doomed sediments, those with a low probability of preservation, imparts a secular trend to fossil preservation. As a result, the fossil record is spatially and temporally non-uniform. Models of fossil preservation should reflect this non-uniformity by using empirical estimates of fossil preservation that are spatially and temporally partitioned, or by using indirect proxies of fossil preservation. Geologically, realistic models of preservation will provide substantially more reliable estimates of the origination of clades.This article is part of the themed issue 'Dating species divergences using rocks and clocks'. PMID:27325828

  10. Optimal geometry toward uniform current density electrodes

    International Nuclear Information System (INIS)

    Electrodes are commonly used to inject current into the human body in various biomedical applications such as functional electrical stimulation, defibrillation, electrosurgery, RF ablation, impedance imaging, and so on. When a highly conducting electrode makes direct contact with biological tissues, the induced current density has strong singularity along the periphery of the electrode, which may cause painful sensation or burn. Especially in impedance imaging methods such as the magnetic resonance electrical impedance tomography, we should avoid such singularity since more uniform current density underneath a current-injection electrode is desirable. In this paper, we study an optimal geometry of a recessed electrode to produce a well-distributed current density on the contact area under the electrode. We investigate the geometry of the electrode surface to minimize the edge singularity and produce nearly uniform current density on the contact area. We propose a mathematical framework for the uniform current density electrode and its optimal geometry. The theoretical results are supported by numerical simulations

  11. Adjustable, Broadband, Selective Excitation with Uniform Phase

    Science.gov (United States)

    Cano, Kristin E.; Smith, Mari A.; Shaka, A. J.

    2002-03-01

    An advance in the problem of achieving broadband, selective, and uniform-phase excitation in NMR spectroscopy of liquids is outlined. Broadband means that, neglecting relaxation, any frequency bandwidth may be excited even when the available radiofrequency (RF) field strength is strictly limited. Selective means that sharp transition edges can be created between pure-phase excitation and no excitation at all. Uniform phase means that, neglecting spin-spin coupling, all resonance lines have nearly the same phase. Conventional uniform-phase excitation pulses (e.g., E-BURP), mostly based on amplitude modulation of the RF field, are not broadband: they have an achievable bandwidth that is strictly limited by the peak power available. Other compensated pulses based on adiabatic half-passage, like BIR-4, are not selective. By contrast, inversion pulses based on adiabatic fast passage can be broadband (and selective) in the sense above. The advance outlined is a way to reformulate these frequency modulated (FM) pulses for excitation, rather than just inversion.

  12. Impact of heterogeneities on lateral penumbra in uniform scanning proton therapy

    Directory of Open Access Journals (Sweden)

    Suresh Rana

    2013-12-01

    Full Text Available Purpose: In the treatment planning of uniform scanning proton therapy, an aperture block is designed for each beam with a margin, which typically includes the lateral penumbra measured in water (homogenous medium. However, during real proton therapy treatment, protons may pass through tissues of different densities within the patient's body before they are stopped. The main aim of this study was to investigate the dependency of lateral penumbra on low- and high-density heterogeneities placed in the plateau and spread-out Bragg peak (SOBP regions.Method: The measurements were performed by placing radiographic films at the isocenter (center of SOBP, and each proton beam was delivered with 150 monitor units using standard beam conditions of the institution. Results and Conclusion: The preliminary results from this study showed that the lateral penumbra of uniform scanning proton beams was less sensitive to the inhomogeneities introduced in the protons beam path. The low-density heterogeneity in the plateau region had more impact on the lateral penumbra when compared to the low-density in the SOBP region. In contrast, the placement of high-density heterogeneity (whether in the plateau or SOBP region produced a very minimal difference. The overall difference in lateral penumbra among different phantoms was within ±1 mm.----------------------Cite this article as:Rana S, Singh H. Impact of heterogeneities on lateral penumbra in uniform scanning proton therapy. Int J Cancer Ther Oncol 2013; 1(2:01026.DOI: http://dx.doi.org/10.14319/ijcto.0102.6

  13. Formalizing Implementation Strategies for First-Class Continuations

    DEFF Research Database (Denmark)

    Danvy, Olivier

    1999-01-01

    We present the first formalization of implementation strategies for first-class continuations. The formalization hinges on abstract machines for continuation-passing style (CPS) programs with a special treatment for the current continuation, accounting for the essence of first-class continuations....... These abstract machines are proven equivalent to a standard, substitution-based abstract machine. The proof techniques work uniformly for various representations of continuations. As a byproduct, we also present a formal proof of the two folklore theorems that one continuation identifier is enough for...... second-class continuations and that second-class continuations are stackable. A large body of work exists on implementing continuations, but it is predominantly empirical and implementation-oriented. In contrast, our formalization abstracts the essence of first-class continuations and provides a uniform...

  14. Aspects on the optimal photon beam energy for radiation therapy

    International Nuclear Information System (INIS)

    The selection of optimal photon beam energy is investigated both for realistic clinical bremsstrahlung beams and for monoenergetic photon beams. The photon energies covered in this investigation range from 60Co to bremsstrahlung and monoenergetic beams with maximum energies up to 50 MeV. One head and neck tumor and an advanced cervix tumor are investigated and the influence of beam direction is considered. It is shown that the use of optimized intensity modulated photon beams significantly reduces the need of beam energy selection. The most suitable single accelerator potential will generally be in the range 6-15 MV for both superficially located and deep-seated targets, provided intensity-modulated dose delivery is employed. It is also shown that a narrow penumbra region of a photon beam ideally should contain low-energy photons (≤4 MV), whereas the gross tumor volume, particularly when deep-seated targets are concerned, should be irradiated by high-energy photons. The regions where low photon energies are most beneficial are where organs at risk are laterally close to the target volume. The situation is completely changed when uniform or wedged beams are used. The selection of optimal beam energy then becomes a very important task in line with the experience from traditional treatment techniques. However, even with a large number of uniform beam portals, the treatment outcome is substantially lower than with a few optimized intensity-modulated beams. (orig.)

  15. Hough Transform Based Corner Detection for Laser Beam Positioning

    International Nuclear Information System (INIS)

    In laser beam alignment in addition to detecting position, one must also determine the rotation of the beam. This is essential when a commissioning new laser beam for National Ignition Facility located at the Lawrence Livermore National Laboratory. When the beam is square, the positions of the corners with respect to one another provides an estimate of the rotation of the beam. This work demonstrates corner detection in the presence or absence of a second order non-uniform illumination caused by a spatial mask. The Hough transform coupled with illumination dependent pre-processing is used to determine the corner points. We show examples from simulated and real NIF images

  16. Controlling beam halo-chaos via backstepping design

    Institute of Scientific and Technical Information of China (English)

    Gao Yuan; Kong Feng

    2008-01-01

    A backstepping control method is proposed for controlling beam halo-chaos in the periodic focusing channels PFCs) of high-current ion accelerator. The analysis and numerical results show that the method, via adjusting an exterior magnetic field, is effective to control beam halo chaos with five types of initial distribution ion beams, all statistical quantities of the beam halo-chaos are largely reduced, and the uniformity of ion beam is improved. This control method has an important value of application, for the exterior magnetic field can be easily adjusted in the periodical magnetic focusing channels in experiment.

  17. Hough Transform Based Corner Detection for Laser Beam Positioning

    Energy Technology Data Exchange (ETDEWEB)

    Awwal, A S

    2005-07-26

    In laser beam alignment in addition to detecting position, one must also determine the rotation of the beam. This is essential when a commissioning new laser beam for National Ignition Facility located at the Lawrence Livermore National Laboratory. When the beam is square, the positions of the corners with respect to one another provides an estimate of the rotation of the beam. This work demonstrates corner detection in the presence or absence of a second order non-uniform illumination caused by a spatial mask. The Hough transform coupled with illumination dependent pre-processing is used to determine the corner points. We show examples from simulated and real NIF images.

  18. 桩土相互作用对高速铁路连续梁桥地震响应的影响%The Pile-soil Interaction Impact on the Seismic Response of Continuous Beam Bridge in High-speed Railway

    Institute of Scientific and Technical Information of China (English)

    陶竑宇

    2013-01-01

      本文基于 Midas Civil,运用 m 法模拟了桩土相互作用对高速铁路连续梁桥地震响应的影响。实验发现,考虑桩土相互作用时,地震响应明显增大,且地震响应规律差异明显。这是准确计算地震对高速铁路连续梁桥影响的不可忽略因素。%This article bases on Midas Civil, use the method of m to simulate the pile-soil interaction impact on the seismic response of continuous beam bridge in high-speed railway. And the author discovers that when considering the pile-soil interaction, the seismic response is significantly increased, and the differences of the seismic response law are obvious, which is the factor that cannot be ignored to accurately calculate the earthquake on the continuous beam bridge in high-speed rail-way.

  19. Beam spill control with frequency modulation in electron synchrotron

    International Nuclear Information System (INIS)

    The new method has been applied to the beam spill control of the INS electron synchrotron. In this method, the RF operating frequency is slowly increased at the final stage of the accelerating period. Then the equilibrium orbit shrinks and the beam hits the radiator gradually, staying in the stable phase. The new method gives the uniform beam spill in the energy region below 700 MeV where the old method has not been successful enough. (author)

  20. Proceedings of the beam-beam interaction seminar

    International Nuclear Information System (INIS)

    The beam-beam interaction has been and continues to be a performance limiting effect in colliding beam systems. Electron-positron collisions are typically more than a factor of five lower in luminosity than expectations from beam design and with present understanding, extrapolations to future systems are not satisfactory. Prediction and optimized design are even more uncertain for proton-proton and proton-antiproton future systems with the ISR at CERN being the sole precedent. The very health of the high energy physics program in the next decades depends to a significant extent on our ability to unravel the mechanisms of this phenomenon and to control them. There have been a variety of studies, including a plasma model of e+e- collisions, models emphasizing the effects of noise and a model involving a diffusion-damping equilibrium. Various nonlinear analyses of the beam-beam systems have also been performed. And finally an entirely new form of beam-beam configuration has been proposed and studied - the very strong single pass collider. In view of this extensive and broad effort, there was organized an informal seminar to bring many of these ideas into an open forum. This seminar was held at SLAC on May 22 and 23, 1980. Contributors, totaling seventeen, came from universities and national laboratories across the United States. These proceedings represent a record of the seminar. The written versions of the papers presented were submitted by the authors and are included here without editing

  1. Active Beam Spectroscopy

    Science.gov (United States)

    von Hellermann, M. G.; Delabie, E.; Jaspers, R. J. E.; Biel, W.; Marchuk, O.; Summers, H. P.; Whiteford, A.; Giroud, C.; Hawkes, N. C.; Zastrow, K. D.

    2008-03-01

    Charge eXchange Recombination Spectroscopy (CXRS) plays a pivotal role in the diagnostics of hot fusion plasmas and is implemented currently in most of the operating devices. In the present report the main features of CXRS are summarized and supporting software packages encompassing "Spectral Analysis Code CXSFIT", "Charge Exchange Analysis Package CHEAP", and finally "Forward Prediction of Spectral Features" are described. Beam Emission Spectroscopy (BES) is proposed as indispensable cross-calibration tool for absolute local impurity density measurements and also for the continuous monitoring of the neutral beam power deposition profile. Finally, a full exploitation of the `Motional Stark Effect' pattern is proposed to deduce local pitch angles, total magnetic fields and possibly radial electric fields. For the proposed active beam spectroscopy diagnostic on ITER comprehensive performance studies have been carried out. Estimates of expected spectral signal-to-noise ratios are based on atomic modelling of neutral beam stopping and emissivities for CXRS, BES and background continuum radiation as well as extrapolations from present CXRS diagnostic systems on JET, Tore Supra, TEXTOR and ASDEX-UG. Supplementary to thermal features a further promising application of CXRS has been proposed recently for ITER, that is a study of slowing-down alpha particles in the energy range up to 2 MeV making use of the 100 keV/amu DNB (Diagnostic Neutral Beam) and the 500 keV/amu HNB (Heating Neutral Beam). Synthetic Fast Ion Slowing-Down spectra are evaluated in terms of source rates and slowing-down parameters

  2. Existence results for boundary problems for uniformly elliptic and parabolic fully nonlinear equations

    Directory of Open Access Journals (Sweden)

    M. G. Crandall

    1999-07-01

    Full Text Available We study existence of continuous weak (viscosity solutions of Dirichlet and Cauchy-Dirichlet problems for fully nonlinear uniformly elliptic and parabolic equations. Two types of results are obtained in contexts where uniqueness of solutions fails or is unknown. For equations with merely measurable coefficients we prove solvability of the problem, while in the continuous case we construct maximal and minimal solutions. Necessary barriers on external cones are also constructed.

  3. A Uniform Framework of Global Nuclear Materials Management

    International Nuclear Information System (INIS)

    Global Nuclear Materials Management (GNMM) anticipates and supports a growing international recognition of the importance of uniform, effective management of civilian, excess defense, and nuclear weapons materials. We expect thereto be a continuing increase in both the number of international agreements and conventions on safety, security, and transparency of nuclear materials, and the number of U.S.-Russian agreements for the safety, protection, and transparency of weapons and excess defense materials. This inventory of agreements and conventions may soon expand into broad, mandatory, international programs that will include provisions for inspection, verification, and transparency, To meet such demand the community must build on the resources we have, including State agencies, the IAEA and regional organizations. By these measures we will meet the future expectations for monitoring and inspection of materials, maintenance of safety and security, and implementation of transparency measures

  4. A Uniform Framework of Global Nuclear Materials Management

    Energy Technology Data Exchange (ETDEWEB)

    Dupree, S.A.; Mangan, D.L.; Sanders, T.L; Sellers, T.A.

    1999-04-20

    Global Nuclear Materials Management (GNMM) anticipates and supports a growing international recognition of the importance of uniform, effective management of civilian, excess defense, and nuclear weapons materials. We expect thereto be a continuing increase in both the number of international agreements and conventions on safety, security, and transparency of nuclear materials, and the number of U.S.-Russian agreements for the safety, protection, and transparency of weapons and excess defense materials. This inventory of agreements and conventions may soon expand into broad, mandatory, international programs that will include provisions for inspection, verification, and transparency, To meet such demand the community must build on the resources we have, including State agencies, the IAEA and regional organizations. By these measures we will meet the future expectations for monitoring and inspection of materials, maintenance of safety and security, and implementation of transparency measures.

  5. On acoustic wave generation in uniform shear flow

    Science.gov (United States)

    Gogoberidze, G.

    2016-07-01

    The linear dynamics of acoustic waves and vortices in uniform shear flow is studied. For flows with very low shear rates, the dynamics of perturbations is adiabatic and can be described by the WKB approximation. However, for flows with moderate and high shear rates the WKB approximation is not appropriate, and alternative analysis shows that two important phenomena occur: acoustic wave over-reflection and wave generation by vortices. The later phenomenon is a known linear mechanisms for sound generation in shear flows, a mechanism that is related to the continuous spectrum that arises in linear shear flow dynamics. A detailed analytical study of these phenomena is performed and the main quantitative and qualitative characteristics of the radiated acoustic field are obtained and analyzed.

  6. Fabrication of a uniformly sized fenofibrate microemulsion by membrane emulsification.

    Science.gov (United States)

    Pradhan, Roshan; Lee, Dong Won; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

    2013-01-01

    Fenofibrate-loaded microemulsions composed of Labrafil M 1944 CS, Capryol PGMC and fenofibrate as the dispersed phase and Labrasol in demineralised water as the continuous phase were prepared by utilising a Shirasu-porous-glass (SPG) membrane emulsification technique. The process parameters were optimised by adjusting the feed pressure (15-45 kPa), agitator speed (250-800 rpm) and temperature of the continuous phase (25-45°C). As a result, narrowly distributed microemulsions were obtained via SPG membrane emulsification at an agitator speed of 250 rpm, a feed pressure of 30 kPa and a continuous phase temperature of 25°C. Furthermore, TEM images clearly showed that the microemulsion prepared by SPG membrane emulsification had a uniform, spherical morphology with a narrow size distribution. Our results indicated that the SPG membrane emulsification technique is highly efficient for the preparation of narrowly distributed microemulsions with relatively smaller particle sizes compared with the common stirring method. PMID:22657749

  7. Generalized Continued Logarithms and Related Continued Fractions

    OpenAIRE

    Borwein, Jonathan M.; Hare, Kevin G.; Lynch, Jason G.

    2016-01-01

    We study continued logarithms as introduced by Bill Gosper and studied by J. Borwein et. al.. After providing an overview of the type I and type II generalizations of binary continued logarithms introduced by Borwein et. al., we focus on a new generalization to an arbitrary integer base $b$. We show that all of our so-called type III continued logarithms converge and all rational numbers have finite type III continued logarithms. As with simple continued fractions, we show that the continued ...

  8. Design, Fabrication and Installation of the Steering Magnet with High Uniformity of Magnetic field for KOMAC Beamline

    International Nuclear Information System (INIS)

    The KOMAC (Korea Multi-Purpose Accelerator Complex) provides user and the proton beam at a 20-MeV and a 100-MeV beamline as it forms a proton beam transport. The purpose of the steering magnet is to provide a beam to a target accurately and used for this reason. The most important factor of the steering magnet is integrated magnetic field. The beam is steered this factor. The following factors is magnetic field uniformity for steering evenly the whole of beam cross section. Also alignment of the device by this factor is relatively ease. The field uniformity was under 2% at transverse section of a steering magnet as simulation condition. The kick angle was 4-mrad by characteristics of KOMAC beamline, and the integration field was calculated as 0.0050-Tm. The 2-demensional (2D) design was simulated by Poisson code, and the 3- dimensional (3D) was simulated by CST EM Studio. The steering magnet was installed in the beamline and bipolar DC power supply was consist of EPICS control by RS-232 communication. Integrated magnetic field was measured 0.0053-Tm for the steered 4 mrad at 100-MeV proton beam. The steering magnet was installed at beamline and the power supply was controlled by EPICS for remote system. The steering magnets are expected to improve the beam performance of accurate delivery to the target

  9. Design, Fabrication and Installation of the Steering Magnet with High Uniformity of Magnetic field for KOMAC Beamline

    Energy Technology Data Exchange (ETDEWEB)

    Chung, B. H.; Kim, J. H.; Kim, H. S.; Kwon, H. J.; Cho, Y. S. [Korea Multipurpose Accelerator Complex, Gyeongju (Korea, Republic of)

    2015-05-15

    The KOMAC (Korea Multi-Purpose Accelerator Complex) provides user and the proton beam at a 20-MeV and a 100-MeV beamline as it forms a proton beam transport. The purpose of the steering magnet is to provide a beam to a target accurately and used for this reason. The most important factor of the steering magnet is integrated magnetic field. The beam is steered this factor. The following factors is magnetic field uniformity for steering evenly the whole of beam cross section. Also alignment of the device by this factor is relatively ease. The field uniformity was under 2% at transverse section of a steering magnet as simulation condition. The kick angle was 4-mrad by characteristics of KOMAC beamline, and the integration field was calculated as 0.0050-Tm. The 2-demensional (2D) design was simulated by Poisson code, and the 3- dimensional (3D) was simulated by CST EM Studio. The steering magnet was installed in the beamline and bipolar DC power supply was consist of EPICS control by RS-232 communication. Integrated magnetic field was measured 0.0053-Tm for the steered 4 mrad at 100-MeV proton beam. The steering magnet was installed at beamline and the power supply was controlled by EPICS for remote system. The steering magnets are expected to improve the beam performance of accurate delivery to the target.

  10. A study on beam profile at an industrial electron beam accelerator

    International Nuclear Information System (INIS)

    An industrial type electron beam accelerator located at BARC-BRIT complex, Vashi, Navi Mumbai is operational for development of applications and technology demonstration to the Indian industry in the field of polymer modifications and for processing of various other products. Recently the accelerator has been upgraded from 2 MeV to 5 MeV to process thick polymers, packaged products and for waste water treatment. This accelerator is capable of delivering powered electron beams up to 15 kW average beam power in the energy range 3 to 5 MeV. In the facility, product is irradiated either in static or conveyor mode of operation under the scanning- type beam. In the present work, we have performed beam profile measurement at different distances from the beam extraction window under conveyor and static mode of operation. We have used cellulose triacetate (CTA) strip dosimeters for the beam profile measurement. Dose profile measured along the scan direction (beam width) in conveyor mode and beam length profile in static mode of operation at different distances below accelerator beam exit window is shown. In the conveyor mode of operation, as the distance increases from the beam window the uniformity of the dose distribution improves but dose decreases linearly with distance. For a scanned beam, the beam width defines the dimension of the beam sweep. For static mode of operation, the dose from the exit window of the accelerator follows inverse relation with distance (i.e. l/r). This shows that the system is a line-type directional radiation source. Beam length is critical for processes where product is stationary under the beam and also for setting speed of the conveyor depending on pulse frequency in conveyor mode of operation. The present paper describes optimization of operational parameters to maximize the efficiency of the irradiation process based on these measurements. (author)

  11. Fabrication and evaluation of uniform and gradient density epoxies

    Energy Technology Data Exchange (ETDEWEB)

    Domeier, L.A.; Skala, D.M.; Goods, S.H. [and others

    1997-11-01

    Filled epoxy materials which vary in density in a designed manner have been fabricated and their mechanical properties evaluated. Density variations were produced by incorporating different volume fractions of either glass microballoons (GMB) or alumina. Several different sample types were evaluated including uniform density (0.8 g/cm{sup 3} < {rho} < 2.0 g/cm{sup 3}) samples and gradient density samples (GMB only, 0.8 g/cm{sup 3} < {rho} < 1.2 g/cm{sup 3}). The uniform density specimens were evaluated for the effects of filler type and concentration on modulus and toughness. Results indicated that addition of alumina filler significantly increased the resulting modulus while addition of GMB had little measurable effect. These differences could be understood in terms of the differing moduli of the additives relative to that of the epoxy matrix. In the former case the alumina particulates had a modulus much greater than that of the epoxy while in the latter case, the modulus of the GMB additive was only slightly greater than that of the matrix. Addition of either filler significantly degraded the toughness of the composite specimens and precluded the use of gradients to enhance toughness performance. Discontinuous {open_quotes}block{close_quotes} gradients used for testing were fabricated by simple sequential pours of formulations with different GMB loadings and were evaluated for modulus, strength and ductility. Continuous gradients were fabricated in process studies by programmed shifts in the peristaltic pumping/mixing ratio of epoxies filled with either alumina or GMB. None of the continuous gradient materials were mechanically tested. These results suggest that applications utilizing gradient materials containing alumina and similar high modulus fillers to provide designed stiffness rather than improved toughness are the most appropriate targets for future investigation.

  12. Scheme for Low Energy Beam Transport with a Non-Neutralized Section

    Energy Technology Data Exchange (ETDEWEB)

    Shemyakin, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Prost, L. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-04-23

    A typical Low Energy Beam Transport (LEBT) design relies on dynamics with nearly complete beam space charge neutralization over the entire length of the LEBT. This paper argues that, for a beam with modest perveance and uniform current density distribution when generated at the source, a downstream portion of the LEBT can be un-neutralized without significant emittance growth.

  13. Suppression of Space Charge Induced Beam Halo in Nonlinear Focusing Channel

    CERN Document Server

    Batygin, Yuri K; Kurennoy, Sergey; Li, Chao

    2016-01-01

    An intense non-uniform particle beam exhibits strong emittance growth and halo formation in focusing channels due to nonlinear space charge forces of the beam. This phenomenon limits beam brightness and results in particle losses. The problem is connected with irreversible distortion of phase space volume of the beam in conventional focusing structures due to filamentation in phase space. Emittance growth is accompanied by halo formation in real space, which results in inevitable particle losses. A new approach for solving a self-consistent problem for a matched non-uniform beam in two-dimensional geometry is discussed. The resulting solution is applied to the problem of beam transport, while avoiding emittance growth and halo formation by the use of nonlinear focusing field. Conservation of a beam distribution function is demonstrated analytically and by particle-in-cell simulation for a beam with a realistic beam distribution.

  14. Suppression of space charge induced beam halo in nonlinear focusing channel

    Science.gov (United States)

    Batygin, Yuri K.; Scheinker, Alexander; Kurennoy, Sergey; Li, Chao

    2016-04-01

    An intense non-uniform particle beam exhibits strong emittance growth and halo formation in focusing channels due to nonlinear space charge forces of the beam. This phenomenon limits beam brightness and results in particle losses. The problem is connected with irreversible distortion of phase space volume of the beam in conventional focusing structures due to filamentation in phase space. Emittance growth is accompanied by halo formation in real space, which results in inevitable particle losses. A new approach for solving a self-consistent problem for a matched non-uniform beam in two-dimensional geometry is discussed. The resulting solution is applied to the problem of beam transport, while avoiding emittance growth and halo formation by the use of nonlinear focusing field. Conservation of a beam distribution function is demonstrated analytically and by particle-in-cell simulation for a beam with a realistic beam distribution.

  15. Radiation of charge uniformly moving in medium

    International Nuclear Information System (INIS)

    We analyze how the frequency dependence of the dielectric permittivity affects the electromagnetic field radiated by a point charge uniformly moving in medium. It turns out that a moving charge radiates at every velocity. We study the space distribution of the electromagnetic field and show that its oscillations are due to the time-dependent medium polarization induced by the moving charge. Spectral distributions of the radiated energy and the photon number are given. Consequences arising from the choice of polarization different from the usual one are discussed. The analysis of the Kramers-Kronig dispersion relations for the treated problems is given

  16. Radiative processes of uniformly accelerated entangled atoms

    CERN Document Server

    Menezes, G

    2015-01-01

    We study radiative processes of uniformly accelerated entangled atoms, interacting with an electromagnetic field prepared in the Minkowski vacuum state. We discuss the structure of the rate of variation of the atomic energy for two atoms travelling in different hyperbolic world lines. We identify the contributions of vacuum fluctuations and radiation reaction to the generation of entanglement as well as to the decay of entangled states. Our results resemble the situation in which two inertial atoms are coupled individually to two spatially separated cavities at different temperatures. In addition, for equal accelerations we obtain that the maximally entangled antisymmetric Bell state is a decoherence-free state.

  17. Uniform infinite planar quadrangulations with a boundary

    CERN Document Server

    Curien, Nicolas

    2012-01-01

    We introduce and study the uniform infinite planar quadrangulation (UIPQ) with a boundary via an extension of the construction of arXiv:1201.1052. We then relate this object to its simple boundary analog using a pruning procedure. This enables us to study the aperture of these maps, that is, the maximal distance between two points on the boundary, which in turn sheds new light on the geometry of the UIPQ. In particular we prove that the self-avoiding walk on the UIPQ is diffusive.

  18. Stretching of proteins in a uniform flow

    OpenAIRE

    Szymczak, P.; Cieplak, Marek

    2006-01-01

    Stretching of a protein by a fluid flow is compared to that in a force-clamp apparatus. The comparison is made within a simple topology-based dynamical model of a protein in which the effects of the flow are implemented using Langevin dynamics. We demonstrate that unfolding induced by a uniform flow shows a richer behavior than that in the force clamp. The dynamics of unfolding is found to depend strongly on the selection of the amino acid, usually one of the termini, which is anchored. These...

  19. Stretching of proteins in a uniform flow

    Science.gov (United States)

    Szymczak, P.; Cieplak, Marek

    2006-10-01

    Stretching of a protein by a fluid flow is compared to that in a force-clamp apparatus. The comparison is made within a simple topology-based dynamical model of a protein in which the effects of the flow are implemented using Langevin dynamics. We demonstrate that unfolding induced by a uniform flow shows a richer behavior than that in the force clamp. The dynamics of unfolding is found to depend strongly on the selection of the amino acid, usually one of the termini, which is anchored. These features offer potentially wider diagnostic tools to investigate structure of proteins compared to experiments based on the atomic force microscopy.

  20. Radionic Non-uniform Black Strings

    OpenAIRE

    Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro

    2003-01-01

    Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of the black strings. From the brane point of view, the black string appears as the deformed dilatonic black hole which becomes dilatonic black hole in the single brane limit and reduces to the Reissner-Nordstr\\"om black hole in the close limit of two-branes. The stability of solutions is demonstrated using the catastrophe theory. From ...