Optodynamics: dynamic aspects of laser beam-surface interaction
Možina, J.; Diaci, J.
2012-05-01
This paper presents a synthesis of the results of our original research in the area of laser-material interaction and pulsed laser material processing with a special emphasis on the dynamic aspects of laser beam-surface interaction, which include the links between the laser material removal and the resulting material motion. In view of laser material processing, a laser beam is not only considered as a tool but also as a generator of information about the material transformation. The information is retained and conveyed by different kinds of optically induced mechanical waves. Several generation/detection schemes have been developed to extract this information, especially in the field of non-destructive material evaluation. Blast and acoustic waves, which propagate in the air surrounding the work-piece, have been studied using microphone detection as well as various setups of the laser beam deflection probe. Stress waves propagating through the work-piece have been studied using piezoelectric transducers and laser interferometers.
Beam dynamics aspects of crab cavities in the CERN Large Hadron Collider
Sun, Y P; Barranco, J; Tomás, R; Weiler, T; Zimmermann, F; Calaga, R; Morita, A
2009-01-01
Modern colliders bring into collision a large number of bunches to achieve a high luminosity. The long-range beam-beam effects arising from parasitic encounters at such colliders are mitigated by introducing a crossing angle. Under these conditions, crab cavities (CC) can be used to restore effective head-on collisions and thereby to increase the geometric luminosity. Such crab cavities have been proposed for both linear and circular colliders. The crab cavities are rf cavities operated in a transverse dipole mode, which imparts on the beam particles a transverse kick that varies with the longitudinal position along the bunch. The use of crab cavities in the Large Hadron Collider (LHC) may not only raise the luminosity, but it could also complicate the beam dynamics, e.g., crab cavities might not only cancel synchrobetatron resonances excited by the crossing angle but they could also excite new ones, they could reduce the dynamic aperture for off-momentum particles, they could influence the aperture and orbit...
Ekdahl, Carl
2015-01-01
Beam dynamics issues are assessed for a new linear induction electron accelerator being designed for flash radiography of large explosively driven hydrodynamic experiments. Special attention is paid to equilibrium beam transport, possible emittance growth, and beam stability. It is concluded that a radiographic quality beam will be produced possible if engineering standards and construction details are equivalent to those on the present radiography accelerators at Los Alamos.
Energy Technology Data Exchange (ETDEWEB)
Ekdahl, Carl August Jr. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-10-14
Beam dynamics issues are assessed for a new linear induction electron accelerator being designed for flash radiography of large explosively driven hydrodynamic experiments. Special attention is paid to equilibrium beam transport, possible emittance growth, and beam stability. It is concluded that a radiographic quality beam will be produced possible if engineering standards and construction details are equivalent to those on the present radiography accelerators at Los Alamos.
Tecker, F
2014-01-01
The course gives a summary of longitudinal beam dynamics for both linear and circular accelerators. After discussing different types of acceleration methods and synchronism conditions, it focuses on the particle motion in synchrotrons.
Energy Technology Data Exchange (ETDEWEB)
Ben-Zvi I.; Kuczewski A.; Altinbas, Z.; Beavis, D.; Belomestnykh,; Dai, J. et al
2012-07-01
The Collider-Accelerator Department at Brookhaven National Laboratory is building a high-brightness 500 mA capable Energy Recovery Linac (ERL) as one of its main R&D thrusts towards eRHIC, the polarized electron - hadron collider as an upgrade of the operating RHIC facility. The ERL is in final assembly stages, with injection commisioning starting in October 2012. The objective of this ERL is to serve as a platform for R&D into high current ERL, in particular issues of halo generation and control, Higher-Order Mode (HOM) issues, coherent emissions for the beam and high-brightness, high-power beam generation and preservation. The R&D ERL features a superconducting laser-photocathode RF gun with a high quantum efficiency photoccathode served with a load-lock cathode delivery system, a highly damped 5-cell accelerating cavity, a highly flexible single-pass loop and a comprehensive system of beam instrumentation. In this ICFA Beam Dynamics Newsletter article we will describe the ERL in a degree of detail that is not usually found in regular publications. We will discuss the various systems of the ERL, following the electrons from the photocathode to the beam dump, cover the control system, machine protection etc and summarize with the status of the ERL systems.
Dynamic acoustic tractor beams
Energy Technology Data Exchange (ETDEWEB)
Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology – ETC, Santa Fe, New Mexico 87508 (United States)
2015-03-07
Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.
Dynamic acoustic tractor beams
Mitri, F. G.
2015-03-01
Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.
Beam Dynamics and Beam Losses - Circular Machines
Kain, V
2016-01-01
A basic introduction to transverse and longitudinal beam dynamics as well as the most relevant beam loss mechanisms in circular machines will be presented in this lecture. This lecture is intended for physicists and engineers with little or no knowledge of this subject.
Dynamic aspects of musical imagery.
Halpern, Andrea R
2012-04-01
Auditory imagery can represent many aspects of music, such as the starting pitches of a tune or the instrument that typically plays it. In this paper, I concentrate on more dynamic, or time-sensitive aspects of musical imagery, as demonstrated in two recently published studies. The first was a behavioral study that examined the ability to make emotional judgments about both heard and imagined music in real time. The second was a neuroimaging study on the neural correlates of anticipating an upcoming tune, after hearing a cue tune. That study found activation of several sequence-learning brain areas, some of which varied with the vividness of the anticipated musical memory. Both studies speak to the ways in which musical imagery allows us to judge temporally changing aspects of the represented musical experience. These judgments can be quite precise, despite the complexity of generating the rich internal representations of imagery. PMID:22524360
Notes on beam dynamics in linear accelerators
Energy Technology Data Exchange (ETDEWEB)
Gluckstern, R.L.
1980-09-01
A collection of notes, on various aspects of beam dynamics in linear accelerators, which were produced by the author during five years (1975 to 1980) of consultation for the LASL Accelerator Technology (AT) Division and Medium-Energy Physics (MP) Division is presented.
Dynamical aspects of isotopic scaling
Veselsky, M
2006-01-01
Investigation of the effect of dynamical stage established that the increasing width of initial Gaussian distributions is reflected by significant modification of the slope of final isoscaling plots after de-excitation. For narrow initial Gaussian distributions, the slope of isoscaling plots assumes the limiting value for two individual initial nuclei while for wide initial Gaussian distributions the slope for hot fragments approaches the initial value. The slopes of isoscaling plots for final cold fragments increase due to secondary emission. The experimentally observed evolution of the isoscaling parameter in the multifragmentation of hot quasiprojectiles at 50 AMeV, fragmentation of 86Kr beam at 25 AMeV and multifragmentation of target spectator at relativistic energies was reproduced by the simulation with dynamical stage described using the appropriate model (deep inelastic transfer and incomplete fusion for Fermi energy domain and spectator-participant model for relativistic energies) and de-excitation ...
Beam dynamics for induction accelerators
Energy Technology Data Exchange (ETDEWEB)
Lee, Edward P., E-mail: eplee@lbl.gov
2014-01-01
An induction linac uses pulsed power that is applied directly, without any intervening resonant cavities, to accelerate a charged particle pulse. This approach can accommodate a large multiple-beam focusing lattice capable of transporting a large total beam current with a long pulse duration, which may be compressed while accelerating as well as afterward. The mean accelerating gradient is relatively low (less than about 1.5 MV/m), but the potential efficiency of energy transfer can be large up to about 50%. A multiple-beam induction linac is therefore a natural candidate accelerator for a heavy ion fusion (HIF) driver. However, the accelerated beams must meet stringent requirements on occupied phase space volume in order to be focused accurately and with small radius onto the fusion target. Dynamical considerations in the beam injector and linac, as well as in the final compression, final focus, and the fusion chamber, determine the quality of the driver beams as they approach the target. Requirements and tolerances derived from beam dynamics strongly influence the linac configuration and component design. After a summary of dynamical considerations, two major topics are addressed here: transportable current limits, which determine the choice of focal system for the linac, and longitudinal control of the beams, which are potentially destabilized by their interaction with the pulsed power system.
Quasiclassical Calculations in Beam Dynamics
Fedorova, A N; Fedorova, Antonina N.; Zeitlin, Michael G.
2000-01-01
We present some applications of general harmonic/wavelet analysis approach (generalized coherent states, wavelet packets) to numerical/analytical calculations in (nonlinear) quasiclassical/quantum beam dynamics problems. (Naive) deformation quantization, multiresolution representations and Wigner transform are the key points.
Theoretical aspects of Chiral Dynamics
Leutwyler, H
2015-01-01
Many of the quantities of interest at the precision frontier in particle physics require a good understanding of the strong interaction at low energies. The present talk reviews the theoretical framework used in this context. In particular, I draw attention to the fact that applications of effective field theory methods in the low energy domain involve two different aspects: dependence of the quantities of interest on the quark masses and dependence on the momenta. While the lattice approach gives an excellent handle on the low energy constants that govern the quark mass dependence, the most efficient tool to pin down the momentum dependence is dispersion theory. At the same time, the dispersive analysis enlarges the energy range where the effective theory applies. In the meson sector, the interplay of the various sources of information has led to a coherent framework that describes the low energy structure at remarkably high resolution. The understanding of the low energy properties in the baryon sector is l...
Institute of Scientific and Technical Information of China (English)
李满; 宋笔锋; 焦景山; 胡铁玉
2013-01-01
高空长航时大展弦比无人机机翼结构刚度小，在飞行中变形幅度大且特征频率低，与无人机飞行动力学响应耦合，改变了无人机的飞行动力学特性。为研究其影响，对大展弦比机翼结构进行空间梁假设，利用Hodges本征梁动力学模型，结合大展弦比气动力片条理论和准定常假设对无人机进行建模，计算配平状态下无人机的静变形。机翼柔性改变了无人机的纵向静稳定性，在不同推力分布下，计算并比较柔性无人机纵向静稳定性变化。计算不同飞行高度、结构刚度和有效载荷挂载情形下的无人机的纵向飞行品质，结果显示由于静弹性变形改变无人机配平状态下的俯仰转动惯量，导致无人机的纵向短周期频率减小，阻尼增大。由于机翼柔性的影响，无人机纵向长周期运动与结构弯曲变形运动发生耦合。%The high aspect ratio wing of the High Altitude Long Endurance ( HALE) UAV is flexible, causing the UAV to have large structural deformation .Adopting the spatial beam assumption of the high aspect ratio wing , this paper studies the flight dynamics of the UAV uses Hodges intrinsic beam dynamics model combined with aerody -namic strip theory and quasi-steady assumption , uses this method , computes the static deformation in trim state , analyzes the stability in different thrust distribution , calculates the flying qualities in different altitudes , structural rigidities and payload distributions .The results and their analysis show preliminarily that:( 1) the flexible high as-pect ratio wing changes the longitudinal static stability and the pitch inertia of the UAV , resulting in decreased short cycle frequency and increased damping;( 2) the phugoid motion couples with structure bending motion .
Spacecraft Dynamic Characteristics While Deploying Flexible Beams
Institute of Scientific and Technical Information of China (English)
程绪铎; 李俊峰; 樊勇; 王照林
2002-01-01
The attitude dynamic equations of a spacecraft while deploying two flexible beams and the beam equations were developed from momentum theory. The dynamic equations were solved numerically using the Runge-Kutta method to calculate the vibration amplitudes of the flexible beams and the attitude angular velocity. The results show that the vibration amplitudes increase as the beam length increases or as the initial attitude angular velocity increases. The results also show that the vibration amplitudes decrease as the deployment velocity increases.
Large deformation dynamic bending of composite beams
Derian, Edward J.
1985-01-01
The large deformation response of composite beams subjected to a dynamic axial load was studied. The beams were loaded with a moderate amount of eccentricity to promote bending. The study was primarily experimental but some finite element results were obtained. Both the deformation and the failure of the beams were of interest. The static response of the beams was also studied in order to determine the difference between the static and dynamic failure. Twelve different la...
Mathematical aspects of infectious disease dynamics
Boldin, B.
2007-01-01
The thesis `Mathematical aspects of infectious disease dynamics' by Barbara Boldin is about model formulation, analysis and interpretation of four questions arising from biology or medicine. Suppose that a new population is introduced into a steady community. When the basic reproduction ratio R_0 of
Statics and rotational dynamics of composite beams
Ghorashi, Mehrdaad
2016-01-01
This book presents a comprehensive study of the nonlinear statics and dynamics of composite beams and consists of solutions with and without active elements embedded in the beams. The static solution provides the initial conditions for the dynamic analysis. The dynamic problems considered include the analyses of clamped (hingeless) and articulated (hinged) accelerating rotating beams. Two independent numerical solutions for the steady state and the transient responses are presented. The author illustrates that the transient solution of the nonlinear formulation of accelerating rotating beam converges to the steady state solution obtained by the shooting method. Other key areas considered include calculation of the effect of perturbing the steady state solution, coupled nonlinear flap-lag dynamics of a rotating articulated beam with hinge offset and aerodynamic damping, and static and dynamic responses of nonlinear composite beams with embedded anisotropic piezo-composite actuators. The book is intended as a t...
Introduction to Transverse Beam Dynamics
Holzer, B J
2014-01-01
In this chapter we give an introduction to the transverse dynamics of the particles in a synchrotron or storage ring. The emphasis is more on qualitative understanding rather than on mathematical correctness, and a number of simulations are used to demonstrate the physical behaviour of the particles. Starting from the basic principles of how to design the geometry of the ring, we review the transverse motion of the particles, motivate the equation of motion, and show the solutions for typical storage ring elements. Following the usual treatment in the literature, we present a second way to describe the particle beam, using the concept of the emittance of the particle ensemble and the beta function, which reflects the overall focusing properties of the ring. The adiabatic shrinking due to Liouville's theorem is discussed as well as dispersive effects in the most simple case.
Nonlinear dynamics new directions theoretical aspects
Ugalde, Edgardo
2015-01-01
This book, along with its companion volume, Nonlinear Dynamics New Directions: Models and Applications, covers topics ranging from fractal analysis to very specific applications of the theory of dynamical systems to biology. This first volume is devoted to fundamental aspects and includes a number of important new contributions as well as some review articles that emphasize new development prospects. The second volume contains mostly new applications of the theory of dynamical systems to both engineering and biology. The topics addressed in the two volumes include a rigorous treatment of fluctuations in dynamical systems, topics in fractal analysis, studies of the transient dynamics in biological networks, synchronization in lasers, and control of chaotic systems, among others. This book also: · Presents a rigorous treatment of fluctuations in dynamical systems and explores a range of topics in fractal analysis, among other fundamental topics · Features recent developments on...
Cyclotron beam dynamic simulations in MATLAB
International Nuclear Information System (INIS)
MATLAB is useful for beam dynamic simulations in cyclotrons. Programming in an easy-to-use environment permits creation of models in a short space of time. Advanced graphical tools of MATLAB give good visualization features to created models. The beam dynamic modeling results with an example of two different cyclotron designs are presented. Programming with MATLAB opens wide possibilities of the development of the complex program, able to perform complete block of calculations for the design of the accelerators
Quantum fluctuations in beam dynamics
International Nuclear Information System (INIS)
Quantum effects could become important for particle and photon beams used in high-luminosity and high brightness applications in the current and next generation accelerators and radiation sources. This paper is a review of some of these effects
Beam dynamics in high energy particle accelerators
Wolski, Andrzej
2014-01-01
Particle accelerators are essential tools for scientific research in fields as diverse as high energy physics, materials science and structural biology. They are also widely used in industry and medicine. Producing the optimum design and achieving the best performance for an accelerator depends on a detailed understanding of many (often complex and sometimes subtle) effects that determine the properties and behavior of the particle beam. Beam Dynamics in High Energy Particle Accelerators provides an introduction to the concepts underlying accelerator beam line design and analysis, taking an approach that emphasizes the elegance of the subject and leads into the development of a range of powerful techniques for understanding and modeling charged particle beams.
Nonlinear Beam Dynamics and Effects of Wigglers
Fedorova, A N; Fedorova, Antonina N.; Zeitlin, Michael G.
2000-01-01
We present the applications of variational--wavelet approach for the analytical/numerical treatment of the effects of insertion devices on beam dynamics. We investigate the dynamical models which have polynomial nonlinearities and variable coefficients. We construct the corresponding wavelet representation for wigglers and undulator magnets.
High aspect ratio 3D nanopatterning using Proton Beam Writing
van Kan, Jeroen A.
2009-03-01
Proton beam writing (PBW) is a new direct write lithography using MeV protons, and is unique because of its ability to fabricate 3D structures of high aspect ratio structures directly in resist material like PMMA, SU-8 and HSQ. The introduction by CIBA, Singapore of a dedicated PBW facility, capable of writing at the micro- and nano- scale has facilitated high aspect ratio nanostructuring. PBW has demontrated high aspect ratio walls in HSQ down to the 20nm level. In recent experiments details down to sub 20 nm have been achieved in PMMA. Monte-Carlo calculations have shown that structuring down to the nanometer level is feasible. All this is possible because of the virtual absence of proximity effects (unwanted resist exposure by stray secondary electrons). The design and performance of this unique nanoprobe facility will be discussed. Two potential fields of application (eg nanofluidics and nanowire integration) of PBW will be discussed. Currently nanofluidics devices have typically only one critical dimension below 100 nm. Here we will introduce PBW as a powerful technique to fabricate molds for replication of PDMS nanofluidic circuits down to the sub 100 nm level in two dimensions. Initial chips with dimension down to 150 nm have successfully been used to study DNA folding in quasi-1d nanochannels in tandem with fluorescence imaging. Since the size of these PDMS nanochannels is not limited by the PDMS or PBW further miniaturization down to the sub 100 nm level is a realistic goal and initial results will be discussed. Nanowires are a potential building block for nano-electronic devices, and one critical problem is the integration of nanowires to form contacts. Porous alumina templates and high energy ion-tracks have been used for the production of nanowire templates in a random orientation. Since PBW is the only true 3D direct write nanolithographic technique it can be used to fabricate nanowire templates in a controlled manner.
Engineering parabolic beams with dynamic intensity profiles.
Ruelas, Adrian; Lopez-Aguayo, Servando; Gutiérrez-Vega, Julio C
2013-08-01
We present optical fields formed by superposing nondiffracting parabolic beams with distinct longitudinal wave-vector components, generating light profiles that display intensity fluxes following parabolic paths in the transverse plane. Their propagation dynamics vary depending on the physical mechanism originating interference, where the possibilities include constructive and destructive interference between traveling parabolic beams, interference between stationary parabolic modes, and combinations of these. The dark parabolic region exhibited by parabolic beams permits a straightforward superposition of intensity fluxes, allowing formation of a variety of profiles, which can exhibit circular, elliptic, and other symmetries.
A contemporary guide to beam dynamics
International Nuclear Information System (INIS)
A methodological discussion is given for single particle beam dynamics in circular machines. The discussions are introductory, but (or, even therefore) we avoid to rely on too much simplified concepts. We treat things from a very general and fundamental point of view, because this is the easiest and rightest way to teach how to simulate particle motion and how to analyze its results. We give some principles of particle tracking free from theoretical prejudices. We also introduce some transparent methods to deduce the necessary information from the tracking: many of the traditional beam-dynamics concepts can be abstracted from them as approximate quantities which are valid in certain limiting cases
A contemporary guide to beam dynamics
International Nuclear Information System (INIS)
A methodological discussion is given for single particle beam dynamics in circular machines. The discussions are introductory, but (or, even therefore) we avoid to rely on too much simplified concepts. We treat things from a very general and fundamental point of view, because this is the easiest and rightest way to teach how to simulate particle motion and how to analyze its results. We give some principles of particle tracking free from theoretical prejudices. We also introduce some transparent methods to deduce the necessary information from the tracking: many of the traditional beam-dynamics concepts can be abstracted from them as approximate quantities which are valid in certain limiting cases. (author)
Dynamic Bowtie for Fan-beam CT
Liu, Fenglin; Cong, Wenxiang; Hsieh, Scott; Pelc, Norbert
2013-01-01
A bowtie is a filter used to shape an x-ray beam and equalize its flux reaching different detector channels. For development of spectral CT with energy-discriminative photon-counting (EDPC) detectors, here we propose and evaluate a dynamic bowtie for performance optimization based on a patient model or a scout scan. Our dynamic bowtie modifies an x-ray beam intensity profile by mechanical rotation and adaptive adjustment of the x-ray source flux. First, a mathematical model for dynamic bowtie filtering is established for an elliptical section in fan-beam geometry, and the contour of the optimal bowtie is derived. Then, numerical simulation is performed to compare the performance of the dynamic bowtie in the cases of an ideal phantom and a realistic cross-section relative to the counterparts without any bowtie and with a fixed bowtie respectively. Our dynamic bowtie can equalize the expected numbers of photons in the case of an ideal phantom. In practical cases, our dynamic bowtie can effectively reduce the dy...
Introduction to Longitudinal Beam Dynamics
Holzer, B J
2014-01-01
This chapter gives an overview of the longitudinal dynamics of the particles in an accelerator and, closely related to that, the issue of synchronization between the particles and the accelerating field. Beginning with the trivial case of electrostatic accelerators, the synchronization condition is explained for a number of driven accelerators like Alvarez linacs, cyclotrons and finally synchrotrons and storage rings, where it plays a crucial role. In the case of the latter, the principle of phase focusing is motivated qualitatively as well as on a mathematically more correct level and the problem of operation below and above the transition energy is discussed. Throughout, the main emphasis is more on physical understanding rather than on a mathematically rigorous treatment.
Stochastic beam dynamics in storage rings
International Nuclear Information System (INIS)
In this thesis several approaches to stochastic dynamics in storage rings are investigated. In the first part the theory of stochastic differential equations and Fokker-Planck equations is used to describe the processes which have been assumed to be Markov processes. The mathematical theory of Markov processes is well known. Nevertheless, analytical solutions can be found only in special cases and numerical algorithms are required. Several numerical integration schemes for stochastic differential equations will therefore be tested in analytical solvable examples and then applied to examples from accelerator physics. In particular the stochastically perturbed synchrotron motion is treated. For the special case of a double rf system several perturbation theoretical methods for deriving the Fokker-Planck equation in the action variable are used and compared with numerical results. The second part is concerned with the dynamics of electron storage rings. Due to the synchrotron radiation the electron motion is influenced by damping and exciting forces. An algorithm for the computation of the density function in the phase space of such a dissipative stochastically excited system is introduced. The density function contains all information of a process, e.g. it determines the beam dimensions and the lifetime of a stored electron beam. The new algorithm consists in calculating a time propagator for the density function. By means of this propagator the time evolution of the density is modelled very computing time efficient. The method is applied to simple models of the beam-beam interaction (one-dimensional, round beams) and the results of the density calculations are compared with results obtained from multiparticle tracking. Furthermore some modifications of the algorithm are introduced to improve its efficiency concerning computing time and storage requirements. Finally, extensions to two-dimensional beam-beam models are described. (orig.)
Beam Dynamics Challenges for FCC-ee
AUTHOR|(SzGeCERN)442987; Benedikt, Michael; Oide, Katsunobu; Bogomyagkov, Anton; Levichev, Evgeny; Migliorati, Mauro; Wienands, Uli
2015-01-01
The goals of FCC-ee include reaching luminosities of up to a few 1036 cm-2s-1 per interaction point at the Z pole or some 1034 cm-2s-1 at the ZH production peak, and pushing the beam energy up to ≥175 GeV, in a ring of 100 km circumference, with a total synchrotron-radiation power not exceeding 100 MW. A parameter baseline as well as high-luminosity crab-waist options were described in [1] and [2], respectively. The extremely high luminosity and resulting short beam lifetime (due to radiative Bhabha scattering) are sustained by top-up injection. The FCC-ee design status and typical beam parameters for different modes of operation are reported in [3]. One distinct feature of the FCC-ee design is its conception as a double ring, with separate beam pipes for the two counter-rotating (electron and positron) beams, resembling, in this aspect, the high-luminosity B factories PEP-II, KEKB and SuperKEKB as well as the LHC. The two separate rings do not only permit operation with a large number of bunches, up to a f...
Electron beam irradiation effects on xanthan gum. Rheological aspects
International Nuclear Information System (INIS)
The paper describes the application of electron beam irradiation to xanthum gum as used as ingredient by the food or cosmetics industry in order to establish their radiosensitivity. The edible powder of xanthum gum samples were irradiated in 1mm thick layers of Petri dishes covered by a transparent PVC of films using an EB accelerator Dynamitron (Radiation Dynamics Inc.) model JOB 188, dose rate 11.17 kGy/s, 0.637 MeV, 1.78 mA, 5 kGy per passage, 3.36 m min-1 with doses of 5, 10, 20 and 50kGy. One % aqueous solutions from irradiated and non-irradiated xanthum gum were prepared and the radiation effects were measured following viscosity changes at 25 deg. C using a Brookfield viscometer; model DVIII, spindel L, with Rheocalc software. Viscosity measurements were performed according to our previous experience and the results are the mean of at least 3 experiments
Independent particle aspects of nuclear dynamics
International Nuclear Information System (INIS)
A generalization of the independent particle model from nuclear statics to nuclear dynamics is sought. Attention is centered on the average behavior of nuclear dynamics, as opposed to detailed behavior, such as that characteristic of shell effects in nuclear statics. In many situations, all that is needed is a model of dissipation in nuclear dynamics. 56 references
Beam dynamics studies for photocathode RF gun
International Nuclear Information System (INIS)
Photocathode RF guns are very popular choice as injector for low emittance beams especially to light sources world wide. In demand for these gun is increasing steadily and efforts are on to make 2.6 cell RF Gun as SAMEER as proto type for future use at various laboratories. The base design of this 2.6 cell RF Gun is ready and fabrication is planned in near future. In this paper, we present beam dynamic study results of the gun and methodology to arrive at the operating point. Simulation results for Gaussian with nano-second pulse length will be discussed in detail and proposal for generation of few MeV beam will be presented. (author)
Static and Dynamic Quality Assurance by Aspect Oriented Techniques
Knabe, Christoph
2010-01-01
The overall goal of the described research project was to create applicable quality assurance patterns for Java software systems using the aspect-oriented programming language extension AspectJ 5. We tried to develop aspects to check static quality criteria as a variable mutator convention and architectural layering rules. We successfully developed aspects for automating the following dynamic quality criteria: Parameterized Exception Chaining, Comfortable Declaration of Parameterized Exceptio...
Dual-Beam Atom Laser Driven by Spinor Dynamics
Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Aveline, David
2007-01-01
An atom laser now undergoing development simultaneously generates two pulsed beams of correlated Rb-87 atoms. (An atom laser is a source of atoms in beams characterized by coherent matter waves, analogous to a conventional laser, which is a source of coherent light waves.) The pumping mechanism of this atom laser is based on spinor dynamics in a Bose-Einstein condensate. By virtue of the angular-momentum conserving collisions that generate the two beams, the number of atoms in one beam is correlated with the number of atoms in the other beam. Such correlations are intimately linked to entanglement and squeezing in atomic ensembles, and atom lasers like this one could be used in exploring related aspects of Bose-Einstein condensates, and as components of future sensors relying on atom interferometry. In this atom-laser apparatus, a Bose-Einstein condensate of about 2 x 10(exp 6) Rb-87 atoms at a temperature of about 120 micro-K is first formed through all-optical means in a relatively weak singlebeam running-wave dipole trap that has been formed by focusing of a CO2-laser beam. By a technique that is established in the art, the trap is loaded from an ultrahigh-vacuum magnetooptical trap that is, itself, loaded via a cold atomic beam from an upstream two-dimensional magneto-optical trap that resides in a rubidium-vapor cell that is differentially pumped from an adjoining vacuum chamber, wherein are performed scientific observations of the beams ultimately generated by the atom laser.
Dynamical aspects of behavior generation under constraints
Kozma, Robert; Harter, Derek; Achunala, Srinivas
2007-01-01
Dynamic adaptation is a key feature of brains helping to maintain the quality of their performance in the face of increasingly difficult constraints. How to achieve high-quality performance under demanding real-time conditions is an important question in the study of cognitive behaviors. Animals and humans are embedded in and constrained by their environments. Our goal is to improve the understanding of the dynamics of the interacting brain–environment system by studying human behaviors when ...
Beam dynamics in CIME for third harmonic
International Nuclear Information System (INIS)
This report presents the results from simulations for beam dynamics in CIME third harmonics. Details are given regarding the procedures to reach the adaptation at the inflector exit. The aim of these simulation is to determine, for any given ion, the beam correlations at the inflector exit as well as the current values in the isochronous coils for all the field levels. Although not all the steps of the simulation are thoroughly displayed, the report gathers all the the elements necessary for CIME control. Information useful for controlling the Very Low Energy line, the main field and the isochronous coils are also presented. The report has the following content: I. Introduction. II. The field maps and the used codes. A. The maps of CIME magnetic fields; B. The 3D map of CIME electric potentials; C. The maps of 3D electric potentials in the CIME central region; D. Code LIONS and sorting codes. III. Central region. A. An outlook. B.Central rays; IV. Determination of beam correlations. A. Analytical calculation of adaptation conditions; B. Calculation of adaptation conditions based on particle distributions; C. Creating the beam matrices. D. Calculation method for inverse return correlations. V. Results of simulations. VI. Interpolation of isochronous coils at the referential frequency. VII. The interpolation code PARAM. VIII. Conclusions. The paper is supplemented by 4 appendices. The harmonics 2, 4 and 5 are currently under way and the results will be reported in a future paper
Beam dynamics issues in the FCC
AUTHOR|(CDS)2067437; Benedikt, Michael; Besana, Maria Ilaria; Bruce, Roderik; Bruning, Oliver; Buffat, Xavier; Burkart, Florian; Burkhardt, Helmut; Calatroni, Sergio; Cerutti, Francesco; Fartoukh, Stephane; Fiascaris, Maria; Garion, Cedric; Goddard, Brennan; Hofle, Wolfgang; Holzer, Bernhard; Jowett, John; Kersevan, Roberto; Martin, Roman; Mether, Lotta Maria; Milanese, Attilio; Pieloni, Tatiana; Redaelli, Stefano; Rumolo, Giovanni; Salvant, Benoit; Schaumann, Michaela; Schulte, Daniel; Chapochnikova, Elena; Stoel, Linda; Tambasco, Claudia; Tomas Garcia, Rogelio; Tommasini, Davide; Zimmermann, Frank; Guillermo Canton, Gerardo; Kornilov, Vladimir; Boine-Frankenheim, Oliver; Niedermayer, Uwe; Mitsuhashi, Toshiyuki; Ohmi, Kazuhito; Chance, Antoine; Dalena, Barbara; Payet, Jacques; Bambade, Philip; Faus-Golfe, Angeles; Molson, James; Biarrotte, Jean-Luc; Lachaize, Antoine; Fox, John D; Stupakov, Gennady; Abelleira, Jose; Cruz Alaniz, Emilia; Seryi, Andrei; Appleby, Robert Barrie; Boscolo, Manuela; Collamati, Francesco; Drago, Alessandro; Barranco Garcia, Javier; Khan, Shaukat; Riemann, Bernhard
2016-01-01
The international Future Circular Collider (FCC) study is designing hadron, lepton and lepton-hadron colliders based on a new 100 km tunnel in the Geneva region. The main focus and ultimate goal of the study are high luminosity proton-proton collisions at a centre-of-mass energy of 100 TeV, using 16 T Nb3Sn dipole magnets. Specific FCC beam dynamics issues are related to the large circumference, the high brightness—made available by radiation damping —, the small geometric emittance, unprecedented collision energy and luminosity, the huge amount of energy stored in the beam, large synchrotron radiation power, plus the injection scenarios. In addition to the FCC-hh proper, also a High-Energy LHC (HE-LHC) is being explored, using the FCC-hh magnet technology in the existing LHC tunnel, which can yield a centre-of-mass energy around 25 TeV.
Photorefractive dynamic holography using self-pumped phase conjugate beam
Indian Academy of Sciences (India)
Arun Anand; C S Narayanamurthy
2006-03-01
Dynamic holography in photorefractive materials using self-pumped phase conjugate beam of the object beam itself as the other writing beam is proposed. Our detailed theoretical analysis shows four-fold increase in the diffraction efficiency of dynamic holograms if recorded using this geometry even in photorefractive crystal like BTO (having low optical activity) without applying external field. Detailed theoretical analysis is given.
Practical and research aspects of beam-foil spectroscopy
International Nuclear Information System (INIS)
The application of a heavy-ion accelerator to research in beam-foil spectroscopy requires certain capital equipment which is somewhat unorthodox when viewed from the standpoint of conventional, low-energy nuclear physics. It is necessary that people who wish to expand their accelerator work to include beam-foil studies understand the nature and cost of such major apparatus. We will survey the equipment needs, starting with the particle analyzer at the output of the accelerator and including the equipment used in a variety of beam-foil experiments. Electronic and computer devices will not be discussed since they are essentially identical with those employed in nuclear studies. Considerable attention will be given to optical spectrometers and spectographs including simple instruments which might be used by a laboratory just getting started in beam-foil research, or which has limited financial resources. Attention will be given to the production and use of the exciter foils. We will then discuss some typical beam-foil experiments having to do with the excitation, detection, and analysis of spectral lines from electronic levels in multiply-ionized atoms, and also with the measurement of the mean lives of such levels. Finally, we will review some of the special properties of the beam-foil light source as regards the population of the magnetic sub-states of a given level. Recent work on the character of the emitted light will be presented. That work will deal specifically with the origin of the polarization of the light. The relevant experiments involve varying the angle between the plane of the exciter foil and the particle velocity. (author)
Aspects of Plane Wave (Matrix) String Dynamics
Blau, Matthias; O'Loughlin, Martin; Seri, Lorenzo
2011-01-01
We analyse two issues that arise in the context of (matrix) string theories in plane wave backgrounds, namely (1) the use of Brinkmann- versus Rosen-variables in the quantum theory for general plane waves (which we settle conclusively in favour of Brinkmann variables), and (2) the regularisation of the quantum dynamics for a certain class of singular plane waves (discussing the benefits and limitations of regularisations of the plane-wave metric itself).
Beam stability & nonlinear dynamics. Formal report
Energy Technology Data Exchange (ETDEWEB)
Parsa, Z. [ed.
1996-12-31
his Report includes copies of transparencies and notes from the presentations made at the Symposium on Beam Stability and Nonlinear Dynamics, December 3-5, 1996 at the Institute for Theoretical Physics, University of California, Santa Barbara California, that was made available by the authors. Editing, reduction and changes to the authors contributions were made only to fulfill the printing and publication requirements. We would like to take this opportunity and thank the speakers for their informative presentations and for providing copies of their transparencies and notes for inclusion in this Report.
Information Dynamics and Aspects of Musical Perception
Dubnov, Shlomo
Musical experience has been often suggested to be related to forming of expectations, their fulfillment or denial. In terms of information theory, expectancies and predictions serve to reduce uncertainty about the future and might be used to efficiently represent and "compress" data. In this chapter we present an information theoretic model of musical listening based on the idea that expectations that arise from past musical material are framing our appraisal of what comes next, and that this process eventually results in creation of emotions or feelings. Using a notion of "information rate" we can measure the amount of information between past and present in the musical signal on different time scales using statistics of sound spectral features. Several musical pieces are analyzed in terms of short and long term information rate dynamics and are compared to analysis of musical form and its structural functions. The findings suggest that a relation exists between information dynamics and musical structure that eventually leads to creation of human listening experience and feelings such as "wow" and "aha".
Ewen, Hamish Maclean; Riccardo, Bartolini
The non-linear beam dynamics of a circular accelerator, such as the Large Hadron Collider, can have a significant impact on its operation. In order to avoid limitations on the performance reach of the accelerator, and ensure machine protection, it is vital that the beam dynamics are well understood and controlled. This thesis presents the results of studies of non-linear beam dynamics undertaken on the Large Hadron Collider at CERN, during the 2010 to 2013 period. It sets out to quantify the understanding of the non-linear beam dynamics through the comparison of beam-based measurements to simulation, and where able and appropriate seeks to explain deviations of measurement from the model, and define corrections for relevant aspects of the dynamics. The analyses presented in this thesis represent considerable advances in the understanding of the LHC beam dynamics which should allow for an improved operation of the machine in the coming years.
Directory of Open Access Journals (Sweden)
Kikuchi Takashi
2013-11-01
Full Text Available In a final stage of an accelerator system for heavy ion inertial fusion (HIF, pulse shaping and beam current increase by bunch compression are required for effective pellet implosion. A compact simulator with an electron beam was constructed to understand the beam dynamics. In this study, we investigate theoretically and numerically the beam dynamics for the extreme bunch compression in the final stage of HIF accelerator complex. The theoretical and numerical results implied that the compact experimental device simulates the beam dynamics around the stagnation point for initial low temperature condition.
Electron beam irradiation effects on xanthan gum, rheological aspects
International Nuclear Information System (INIS)
Food ingredients to be used for food processing should be decontaminated in order to prevent food spoilage and food-borne diseases. Xanthan gum is a well-known microbial polysaccharide produced by Xanthomonas campestris used in the hydrocolloid market. This paper describes the application of electron beam (EB) irradiation to xanthan gum as used as ingredient by the food or cosmetics industry in order to establish their radiosensitivity. Viscosity of 1% xanthan gum solutions prepared with the irradiated powder decreased with the increase of the EB irradiation dose. The radiation-induced viscosity detriment of this additive must be considered for practical applications. (author)
ASPECTS OF REGIONAL COMPETITIVENESS THROUGH DYNAMIC PRICES OF PETROLEUM PRODUCTS
Daniela ENACHESCU
2015-01-01
This paper presents aspects regarding the dynamics of prices of petroleum products: gasoline and diesel in Romania in the period 2003(2007)-2014. Both focus on relationship-price raw material and finished product by the impact of market prices. Given that the price of fuel is a key factor in economic development but also in the living of population, this paper has proposed to analyze some aspects of the dynamics of prices of petroleum products in correlation with commodity prices in a competi...
Impact of Dynamic Magnetic fields on the CLIC Main Beam
Snuverink, J; Jach, C; Jeanneret, JB; Schulte, D; Stulle, F
2010-01-01
The Compact Linear Collider (CLIC) accelerator has strong precision requirements on the position of the beam. The beam position will be sensitive to external dynamic magnetic fields (stray fields) in the nanotesla regime. The impact of these fields on the CLIC main beam has been studied by performing simulations on the lattices and tolerances have been determined. Several mitigation techniques will be discussed.
Beam and spin dynamics of hadron beams in intermediate-energy ring accelerators
International Nuclear Information System (INIS)
In this thesis beam and spin dynamics of ring accelerators are described. After a general theoretical treatment methods for the beam optimization and polarization conservation are discussed. Then experiments on spin manipulation at the COSY facility are considered. Finally the beam simulation and accelerator lay-out for the HESR with regards to the FAIR experiment are described. (HSI)
Dynamics of Rigid Bodies and Flexible Beam Structures
DEFF Research Database (Denmark)
Nielsen, Martin Bjerre
Rotational motion is a frequently occurring aspect in many engineering applications such as automobiles, rotating machinery or wind turbine rotors. The present thesis is organized in four parts - all concerning development of efficient computational methods for modeling the dynamic behavior...... is that these can be replaced by a projection operator applied to the external potential gradient and possible external constraint gradients. The third part presents a novel two-node beam element capable of undergoing arbitrary large displacements and finite rotations. The element is expressed explicitly in terms...... of the global components of the position vectors and associated convected base vectors for the element nodes. The kinematics is expressed in a homogeneous quadratic form and the constitutive stiffness is derived from complementary energy of a set of equilibrium modes, each representing a state of constant...
Some fundamental aspects of fluctuations and coherence in charged-particle beams in storage rings
International Nuclear Information System (INIS)
A conceptual survey and exposition is presented of some fundamental aspects of fluctuations and coherence, as well as the interplay between the two, in coasting charged-particle beams - both continuous and bunched - in storage rings. A detailed study is given of the spectral properties of the incoherent phase-space Schottky fluctuations, their propagation as waves in the beam, and the analytic complex coherent beam electromagnetic response or transfer function. The modification or distortion of these by collective interactions is examined in terms of simple regeneration mechanisms. Collective or coherent forces in the beam-storage-ring system are described by defining suitable impedance functions or propagators, and a brief discussion of the coherent collective modes and their stability is provided, including a general and rigorous description of the Nyquist stability criterion. The nature of the critical fluctuations near an instability threshold is explored. The concept of Landau damping and its connection with phase-mixing within the beam is outlined. The important connection between the incoherent fluctuations and the beam response, namely the Fluctuation-Dissipation relation, is revealed. A brief discussion is given of the information degrees of freedom, and effective temperature of the fluctuation signals. Appendices provide a short resume of some general aspects of various interactions in a charged-particle beam-environment system in a storage ring and a general introduction to kinetic theory as applied to particle beams. (orig.)
Molecular beam studies of reaction dynamics
Energy Technology Data Exchange (ETDEWEB)
Lee, Y.T. [Lawrence Berkeley Laboratory, CA (United States)
1993-12-01
The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.
Static and dynamic aspects of an air gap capacitor
IJntema, Dominicus J.; Tilmans, Harrie A.C.
1992-01-01
This paper deals with the theory of an air-gap capacitor used as a micromechanical resonator. Both static and dynamic aspects are discussed. A single-element approach for the electrostatic excitation and capacitive detection of the vibrational motion of the resonators is described. The non-linear ch
Radiation safety aspects of the operation of first three synchrotron beam lines of Indus-2.
Nayak, M K; Nair, Haridas G; Bakshi, A K; Sahani, P K; Singh, Sunil; Khan, Saleem; Verma, Dimple; Dev, Vipin; Sahu, T K; Khare, Mukesh; Kumar, Vijay; Bandyopadhyay, Tapas; Tripathi, R M; Sharma, D N
2015-04-01
Five synchrotron radiation beam lines are commissioned and now under regular operation at the Synchrotron Radiation Source, Indus-2 at Raja Ramanna Centre For Advanced Technology (RRCAT), Indore, India. Nine beam lines are under trial operation, and six beam lines are in the installation stage. In the early phase of installation of beam lines on Indus-2, three bending magnet beam lines, Extended X-ray Absorption Fine Structure (EXAFS, BL-8), Energy Dispersive X-ray Diffraction (EDXRD, BL-11) and Angle Dispersive X-ray Diffraction (ADXRD, BL-12), were installed and commissioned, after approval from Atomic Energy Regulatory Board (AERB), India. These beam lines are pink (BL-8), white (BL-11) and monochromatic (BL-12), which are housed in specially designed shielded hutches. In order to ensure safety of users and other working personnel from ionizing radiations present in these beam lines, several safety systems are incorporated and safety procedures are followed. The paper describes the radiological safety aspects of the three beam lines during its initial commissioning trials and also the measurements on radiation levels carried out in and around the beam line hutches. PMID:25209995
Chaotic dynamics of flexible beams with piezoelectric and temperature phenomena
Energy Technology Data Exchange (ETDEWEB)
Krysko, V.A. [Department of Mathematics and Modeling, Saratov State Technical University, Politehnicheskaya 77, 410054 Saratov (Russian Federation); Awrejcewicz, J., E-mail: awrejcew@p.lodz.pl [Lodz University of Technology, Department of Automation and Biomechanics, 1/15 Stefanowski St., 90-924 Lodz (Poland); Warsaw University of Technology, Department of Vehicles, 84 Narbutta St., 02-524 Warsaw (Poland); Kutepov, I.E.; Zagniboroda, N.A.; Papkova, I.V.; Serebryakov, A.V. [Department of Mathematics and Modeling, Saratov State Technical University, Politehnicheskaya 77, 410054 Saratov (Russian Federation); Krysko, A.V. [Department of Applied Mathematics and Systems Analysis, Saratov State Technical University, Politehnicheskaya 77, 410054 Saratov (Russian Federation)
2013-11-01
The Euler–Bernoulli kinematic model as well as the von Kármán geometric non-linearity are used to derive the PDEs governing flexible beam vibrations. The beam is embedded into a 2D temperature field, and its surface is subjected to action of the electric potential. We report how an increase of the exciting load amplitude yields the beam turbulent behavior, and how the temperature changes a scenario from a regular/laminar to spatio-temporal/turbulent dynamics. Both classical Fourier analysis and Morlet wavelets are used to monitor a strong influence of temperature on regular and chaotic beam dynamics.
Controllable circular Airy beams via dynamic linear potential
Zhong, Hua; Belić, Milivoj R; Li, Changbiao; Wen, Feng; Zhang, Zhaoyang; Zhang, Yanpeng
2016-01-01
We investigate controllable spatial modulation of circular autofocusing Airy beams, under action of different dynamic linear potentials, both theoretically and numerically. We introduce a novel treatment method in which the circular Airy beam is represented as a superposition of narrow azimuthally-modulated one-dimensional Airy beams that can be analytically treated. The dynamic linear potentials are appropriately designed, so that the autofocusing effect can either be weakened or even eliminated when the linear potential exerts a "pulling" effect on the beam, or if the linear potential exerts a "pushing" effect, the autofocusing effect can be greatly strengthened. Numerical simulations agree with the theoretical results very well.
Dynamical aspects in modeling long cantilevering workpieces in tool grinding
de Payrebrune, K. M.; Kröger, M.
2015-10-01
Tool grinding is a complex process in which temporal dynamics of workpiece and grinding wheel, and the material removal process itself, affect the quality of the workpiece. Many existing models already provide the option to study the dynamics of workpiece and grinding wheel or cutting forces and material removal processes, but mostly do not combine these aspects. Here, workpiece dynamics are studied in relation to its structural and geometrical changing properties during machining, and are used to simulate the vibrations and deformation of the workpiece during grinding. In combination with models for the grinding wheel and the material removal process, dependencies of the workpiece dynamics on the workpieces quality are studied and results from this hybrid model are in excellent agreement with empirical measurements. Furthermore, the results demonstrate the significant effects of deformations of the workpiece on its final geometry.
Statistical and dynamic aspects of nuclear multi-fragmentation
International Nuclear Information System (INIS)
In this HDR (Accreditation to supervise research) report, the author reports an investigation of the statistical and dynamic aspects of nuclear multi-fragmentation. He presents the experimental methods (detector, event selection, characteristics of multi-fragmentation events), discusses the statistical approach (characteristics of sorted events, hypothesis of thermodynamic equilibrium, characteristics of primary fragments, discussion of results) and the dynamic approach (initial conditions, comparison between the AMD model and experimental results, fragment production mechanism, other constraints for the AMD model), and finally addresses the multi-fragmentation since its appearance threshold (event selection, characteristics of central collisions and of reaction products, extension to all energies)
Beam dynamics with new booster dipoles
International Nuclear Information System (INIS)
New bending magnets are being designed for the booster synchrotron at RRCAT, Indore with the same effective length and field which will be installed in the existing ring with the same configuration of drifts and quadrupole magnets. Presently sector type dipoles are in use. It is easier to fabricate parallel edge (rectangular type) dipoles but the beam optics gets modified due to edges which provide additional focusing. The effect on tune point can be corrected using two quadrupole families. Studies indicate that the beam emittance is lower in the optics with rectangular type dipoles but the beam injection and extraction are more difficult. In this paper, the beam optics, beam emittance, injection and extraction with two configurations of the dipole magnets are compared. (author)
ASPECTS OF REGIONAL COMPETITIVENESS THROUGH DYNAMIC PRICES OF PETROLEUM PRODUCTS
Directory of Open Access Journals (Sweden)
Daniela\tENACHESCU
2015-06-01
Full Text Available This paper presents aspects regarding the dynamics of prices of petroleum products: gasoline and diesel in Romania in the period 2003(2007-2014. Both focus on relationship-price raw material and finished product by the impact of market prices. Given that the price of fuel is a key factor in economic development but also in the living of population, this paper has proposed to analyze some aspects of the dynamics of prices of petroleum products in correlation with commodity prices in a competitive market in 2003 -2014. In the analized period, price of oil barrel has a dynamics substantially influenced by the global political turbulences but also by lower oil demand due to consumption reduction, especially lately. Increases and decreases were abrupt and unpredictable in the early years of the first decade of the XXI century. Political crises in the Middle East, the economic crisis started in 2007 and especially the crisis in Ukraine and policies adopted by the EU and the US have led to extremely large fluctuations in oil prices from one period to another . This dynamic will only cover the price of petroleum products namely gazoline and diesel for vehicles.
Beam dynamics design of the Compact Linear Collider Drive Beam injector
Energy Technology Data Exchange (ETDEWEB)
Hajari, Sh. Sanaye, E-mail: ssanayeh@cern.ch [Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); European Organization for Nuclear Research (CERN), BE Department, CH-1211 Geneva 23 (Switzerland); Shaker, H. [Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); European Organization for Nuclear Research (CERN), BE Department, CH-1211 Geneva 23 (Switzerland); Doebert, S. [European Organization for Nuclear Research (CERN), BE Department, CH-1211 Geneva 23 (Switzerland)
2015-11-01
In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel to the main linac. The longitudinal and transverse beam dynamics of the Drive Beam injector has been studied in detail and optimized. The injector consists of a thermionic gun followed by a bunching system, some accelerating structures, and a magnetic chicane. The bunching system contains three sub-harmonic bunchers, a prebuncher, and a traveling wave buncher all embedded in a solenoidal magnetic field. The main characteristic of the Drive Beam injector is the phase coding process done by the sub-harmonic bunching system operating at half the acceleration frequency. This process is essential for the frequency multiplication of the Drive Beam. During the phase coding process the unwanted satellite bunches are produced that adversely affects the machine power efficiency. The main challenge is to reduce the population of particles in the satellite bunches in the presence of strong space-charge forces due to the high beam current. The simulation of the beam dynamics has been carried out with PARMELA with the goal of optimizing the injector performance compared to the existing model studied for the Conceptual Design Report (CDR). The emphasis of the optimization was on decreasing the satellite population, the beam loss in the magnetic chicane and limiting the beam emittance growth in transverse plane.
Dynamic stiffness matrix of partial-interaction composite beams
Directory of Open Access Journals (Sweden)
Guangjian Bao
2015-03-01
Full Text Available Composite beams have a wide application in building and bridge engineering because of their advantages of mechanical properties, constructability and economic performance. Unlike static characteristics, the methods of studying the dynamic characteristics of partial-interaction composite beams were limited, especially dynamic stiffness matrix method. In this article, the dynamic stiffness matrix of partial-interaction composite beams was derived based on the assumption of the Euler–Bernoulli beam theory, and then it was used to predict the frequencies of the free vibration of the single-span composite beams with various boundary conditions or different axial forces. The corresponding vibration modes and buckling loads were also obtained. From the comparison with the existing results, the numerical results obtained by the proposed method agreed reasonably with those in the literatures. The dynamic stiffness matrix method is an accurate method which can determine natural vibration frequencies and vibration mode shapes in any precision theoretically. As a result, when the higher precision or natural frequencies of higher order are required, the dynamic stiffness matrix method is superior when compared to other approximate and numerical methods. The dynamic stiffness matrix method can also be combined with the finite-element method to calculate the free vibration frequencies and natural mode shapes of composite beams in complex conditions.
Screw theoretic view on dynamics of spatially compliant beam
Institute of Scientific and Technical Information of China (English)
Xi-lun DING; J.M.SELIG
2010-01-01
Beams with spatial compliance can be deformed as bending in a plane,twisting,and extending.In terms of the screw theory on rigid body motions,the concept of"deflection screw"is introduced,a spatial compliant beam theory via the deflection screw is proposed,and the spatial compliance of such a beam system is presented and analysed based on the material theory and fundamental kinematic assumptions.To study the dynamics of the spatially compliant beam,the potential energy and the kinetic energy of the beam are discussed by using the screw theory to obtain the Lagrangian.The Rayleigh-Ritz method is used to compute the vibrational frequencies based on discussions of boundary conditions and shape functions.The eigenfrequencies of the beam with spatial compliance are compared with those of individual deformation cases,pure bending,extension,or torsion.Finally,dynamics of a robot with two spatial compliant links and perpendicular joints is studied using the spatial compliant beam theory.Coupling between the joint rigid body motions and the deformations of spatial compliant links can easily be found in dynamic simulation.The study shows the effectiveness of using the screw theory to deal with the problems of dynamic modeling and analysis of mechanisms with spatially compliant links.
Temporal nonlinear beam dynamics in infiltrated photonic crystal fibers
DEFF Research Database (Denmark)
Bennet, Francis; Rosberg, Christian Romer; Neshev, Dragomir N.;
-sensing as well as active devices for all-optical switching at low (mW) laser powers. Commercially available PCFs infiltrated with liquids also provide a versatile and compact tool for exploration of the fundamentals of nonlinear beam propagation in periodic photonic structures. To explore the full scientific...... and technological potential of liquid-infiltrated PCFs it is important to understand the temporal dynamics of nonlinear beam propagation in such structures. In this work we consider thermally induced spatial nonlinear effects in infiltrated photonic crystal fibers. We experimentally study the temporal dynamics...... of nonlinear beam reshaping occurring on a short time scale before the establishment of a steady state regime. In experiment, a 532nm laser beam can be injected into a single hole of an infiltrated PCF cladding structure, and the temporal dynamics of the nonlinear response is measured by monitoring...
Calorimeter design-aspects for neutral beam injection on W7-X
Energy Technology Data Exchange (ETDEWEB)
Holtum, D., E-mail: holtum@ipp.mpg.de [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Postfach 1533, D-85740 Garching (Germany); Froeschle, M.; Heinemann, B. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Postfach 1533, D-85740 Garching (Germany); Liebe, T. [Fa. Xenos GmbH, Jugendstr. 2, D-81667 Muenchen (Germany); Nocentini, R.; Riedl, R.; Rong, P. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Postfach 1533, D-85740 Garching (Germany); Schubert, W. [Fa. Xenos GmbH, Jugendstr. 2, D-81667 Muenchen (Germany); Staebler, A. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Postfach 1533, D-85740 Garching (Germany)
2011-10-15
Neutral Beam Injection (NBI) is one of the heating systems for Wendelstein 7-X (W7-X). The beam power of the NBI is measured calorimetrically. Using the knowledge gained from ASDEX-Upgrade operation, the complete calorimeter was re-designed. The design-aspects and the necessary improvements for operation on W7-X are described in this paper. The main aspects improved concern: (i) the adapted slope of the winding drum at the lift, (ii) the adjustable acceleration/deceleration ramp and integrated position sensors, (iii) the improvements of panels in the body, (iv) the accessibility for mounting panels, (v) the water-distribution, and (vi) the centering of the body on the support to fix and reproduce the measuring position. The manufacturing is in progress, installation will start in 2011 and the commissioning is scheduled for the end of 2014.
Calorimeter design-aspects for neutral beam injection on W7-X
International Nuclear Information System (INIS)
Neutral Beam Injection (NBI) is one of the heating systems for Wendelstein 7-X (W7-X). The beam power of the NBI is measured calorimetrically. Using the knowledge gained from ASDEX-Upgrade operation, the complete calorimeter was re-designed. The design-aspects and the necessary improvements for operation on W7-X are described in this paper. The main aspects improved concern: (i) the adapted slope of the winding drum at the lift, (ii) the adjustable acceleration/deceleration ramp and integrated position sensors, (iii) the improvements of panels in the body, (iv) the accessibility for mounting panels, (v) the water-distribution, and (vi) the centering of the body on the support to fix and reproduce the measuring position. The manufacturing is in progress, installation will start in 2011 and the commissioning is scheduled for the end of 2014.
Energy Technology Data Exchange (ETDEWEB)
Lee, S. Y.
2014-04-07
We had carried out a design of an ultimate storage ring with beam emittance less than 10 picometer for the feasibility of coherent light source at X-ray wavelength. The accelerator has an inherent small dynamic aperture. We study method to improve the dynamic aperture and collective instability for an ultimate storage ring. Beam measurement and accelerator modeling are an integral part of accelerator physics. We develop the independent component analysis (ICA) and the orbit response matrix method for improving accelerator reliability and performance. In collaboration with scientists in National Laboratories, we also carry out experimental and theoretical studies on beam dynamics. Our proposed research topics are relevant to nuclear and particle physics using high brightness particle and photon beams.
Special aspects of the dynamic behavior of spherical containment shells
International Nuclear Information System (INIS)
Theoretical investigations of the containment response due to dynamic earthquake loading are common practice in the licensing procedure. Two different aspects are considered; first, the stresses must essentially remain below the yield point; and second, the compressive membrane stresses must not cause buckling near the containment clamping. The computations are usually based on simplified models; deviations from the ideal spherical geometry caused by nozzles with reinforced sections or due to inevitable manufacturing tolerances are usually not considered. However, it is known from experiments with thin cylindrical shells that little deviations from the ideal geometry may have a significant influence on the dynamic response. Similar phenomena might also occur in thin spherical shells. Therefore, theoretical and experimental investigations are carried out in which the influence of imperfections on the dynamic response of spherical containment shells will be determined. Both theoretical and experimental results show that point masses attached to the shell will have a strong, but only local effect on the dynamic containment response. Consequently, simplified decoupled models are adequate for the analysis. A first static buckling experiment shows that two types of buckling modes have to be considered; one mode caused by meridional, and the other mode caused by circumferential compressive stresses. The deformations are concentrated in the clamping region of the shell. (orig.)
Some aspects of the dynamics of AGR gas circulators
International Nuclear Information System (INIS)
The various types of vibration found on the gas circulators of an advanced gas-cooled reactor (Hinkley Point 'B' design) are categorized and described briefly. Those due to rotor unbalance or its lack of straightness are considered in detail where it is attempted to highlight certain aspects of the dynamic behaviour which are considered of particular importance to designers either because of the results themselves or the techniques used in obtaining them; for example, the practical utilization of the finite-element technique in the mathematical modelling process. One interesting aspect relates to the interaction between the circulator rotor modes of vibration and those of the over-hung impeller. Another deals with the condition of a permanent rotor bend near the impeller as the source of vibration excitation. Various states of rotor unbalance have also been simulated. The work led to general conclusions which were utilized in resolving specific questions related to the balancing of refurbished circulators; it also increased the understanding of their dynamic behaviour thus leading to more operational confidence. (author)
Dynamic Behavior of Sandwich Beams With Internal Resonators
Sharma, Bhisham Nar Narain
2013-01-01
Dynamic behavior of sandwich beams with internal resonators was investigated. The effect of inserting spring-mass resonators into the sandwich core was theoretically analyzed and it was shown that a wave attenuation bandgap exists due to local resonance. Steady state experiments were used to demonstrate such an attenuation bandgap. Frequency response functions were obtained for a beam with resonators and without resonators. It was shown that insertion of resonators into the core causes a wave...
Dynamic Stiffness Matrix for a Beam Element with Shear Deformation
Directory of Open Access Journals (Sweden)
Walter D. Pilkey
1995-01-01
Full Text Available A method for calculating the dynamic transfer and stiffness matrices for a straight Timoshenko shear beam is presented. The method is applicable to beams with arbitrarily shaped cross sections and places no restrictions on the orientation of the element coordinate system axes in the plane of the cross section. These new matrices are needed because, for a Timoshenko beam with an arbitrarily shaped cross section, deflections due to shear in the two perpendicular planes are coupled even when the coordinate axes are chosen to be parallel to the principal axes of inertia.
Dynamic analysis for planar beam with clearance joint
Yao, XiaoGuang; Guo, XiaoSong; Feng, YongBao; Yu, ChuanQiang; Ma, Changlin
2015-03-01
An analytical model was presented in this study to describe the dynamic characteristics of a planar rotation beam with clearance joint. The spherical contact model was introduced to calculate the collision forces for the planar revolute joint. Unlike previous research, to acquire an accurate and convergent solution, the second-order coupling term of the beam axial deformation is taken into account. Then, the flexible beam was divided into discrete elements via the finite element method. The dynamic equations of the model were deduced via the Hamilton's principle. Further, the dynamic responses were obtained and analyzed in the non-inertial and inertial coordinates. To prove the validity of the presented methodology, a virtual prototype model with identical conditions was created in ADAMS. A numerical example was simultaneously calculated by the two different approaches. Comparison of the results shows that the two approaches match quite well. Finally, some valuable conclusions describing the inner-joint collision process are extracted and summarized.
Aspects of input processing in the numerical control of electron beam machines
International Nuclear Information System (INIS)
A high-performance Numerical Control has been developed for an Electron Beam Machine. The system is structured into 3 hierarchial levels: Input Processing, Realtime Processing (such as Geometry Interpolation) and the Interfaces to the Electron Beam Machine. The author considers the Input Processing. In conventional Numerical Controls the Interfaces to the control is given by the control language as defined in DIN 66025. State of the art in NC-technology offers programming systems of differing competence covering the spectra between manual programming in the control language to highly sophisticated systems such as APT. This software interface has been used to define an Input Processor that in cooperation with the Hostcomputer meets the requirements of a sophisticated NC-system but at the same time provides a modest stand-alone system with all the basic functions such as interactive program-editing, program storage, program execution simultaneous with the development of another program, etc. Software aspects such as adapting DIN 66025 for Electron Beam Machining, organisation and modularisation of Input Processor Software has been considered and solutions have been proposed. Hardware aspects considered are interconnections of the Input Processor with the Host and the Realtime Processors. Because of economical and development-time considerations, available software and hardware has been liberally used and own development has been kept to a minimum. The proposed system is modular in software and hardware and therefore very flexible and open-ended to future expansion. (Auth.)
On the dynamic stability of shear deformable beams under a tensile load
Caddemi, S.; Caliò, I.; Cannizzaro, F.
2016-07-01
Loss of stability of beams in a linear static context due to the action of tensile loads has been disclosed only recently in the scientific literature. However, tensile instability in the dynamic regime has been only marginally covered. Several aspects concerning the role of shear deformation on the tensile dynamic instability on continuous and discontinuous beams are still to be addressed. It may appear as a paradox, but also for the case of the universally studied Timoshenko beam model, despite its old origin, frequency-axial load diagrams in the range of negative values of the load (i.e. tensile load) has never been brought to light. In this paper, for the first time, the influence of a conservative tensile axial loads on the dynamic behaviour of the Timoshenko model, according to the Haringx theory, is assessed. It is shown that, under increasing tensile loads, regions of positive/negative fundamental frequency variations can be distinguished. In addition, the beam undergoes eigen-mode changes, from symmetric to anti-symmetric shapes, until tensile instability of divergence type is reached. As a further original contribution on the subject, taking advantage of a new closed form solution, it is shown that the same peculiarities are recovered for an axially loaded Euler-Bernoulli vibrating beam with multiple elastic sliders. This latter model can be considered as the discrete counterpart of the Timoshenko beam-column in which the internal sliders concentrate the shear deformation that in the Timoshenko model is continuously distributed. Original aspects regarding the evolution of the vibration frequencies and the relevant mode shapes with the tensile load value are highlighted.
High Dynamic Range Beam Imaging with Two Simultaneously Sampling CCDs
Energy Technology Data Exchange (ETDEWEB)
Evtushenko, Pavel E. [JLAB; Douglas, David R. [JLAB
2013-06-01
Transverse beam profile measurement with sufficiently high dynamic range (HDR) is a key diagnostic to measure the beam halo, understand its sources and evolution. In this contribution we describe our initial experience with the HDR imaging of the electron beam at the JLab FEL. On contrary to HDR measurements made with wire scanners in counting mode, which provide only two or three 1D projections of transverse beam distribution, imaging allows to measure the distribution itself. That is especially important for non-equilibrium beams in the LINACs. The measurements were made by means of simultaneous imaging with two CCD sensors with different exposure time. Two images are combined then numerically in to one HDR image. The system works as an online tool providing HDR images at 4 Hz. An optically polished YAG:Ce crystal with the thickness of 100 {micro}m was used for the measurements. When tested with a laser beam images with the DR of about 10{sup 5} were obtained. With the electron beam the DR was somewhat smaller due to the limitations in the time structure of the tune-up beam macro pulse.
NATO Advanced Study Institute on New Aspects of Nuclear Dynamics
Huberts, P
1989-01-01
The 1988 Summer School on New Aspects of Nuclear Dynamics took place in the style that by now has become a tradition: a series of lectures by well known scientists on modem topics of nuclear physics, where special emphasis is placed on the didactic aspects of the lectures. In the past few years, we have witnessed a rapid evolution of the field of nuclear physics towards novel directions of research. This development is accompanied by the construction of some of the largest experimental facilities ever built for nuclear research. The subjects covered by the Summer School focussed on two main issues currently under active investigation and which will be pursued with the new facilities: the transition from nucleonic to quark degrees of freedom in the decription of nuclear reactions, and the behavior of nuclear matter as one approaches extreme densities and temperatures. These topics in many respects go beyond traditional nuclear physics and the speakers therefore also included high energy physicists. From the re...
Millijoule femtosecond micro-Bessel beams for ultra-high aspect ratio machining.
Mitra, Sambit; Chanal, Margaux; Clady, Raphaël; Mouskeftaras, Alexandros; Grojo, David
2015-08-20
We report on a functional experimental design for Bessel beam generation capable of handling high-energy ultrashort pulses (up to 1.2 mJ per pulse of 50 fs duration). This allows us to deliver intensities exceeding the breakdown threshold for air or any dielectric along controlled micro-filaments with lengths exceeding 4 mm. It represents an unprecedented upscaling in comparison to recent femtosecond Bessel beam micromachining experiments. We produce void microchannels through glass substrates to demonstrate that aspect ratios exceeding 1200∶1 can be achieved by using single high-intensity pulses. This demonstration must lead to new methodologies for deep-drilling and high-speed cutting applications. PMID:26368773
Millijoule femtosecond micro-Bessel beams for ultra-high aspect ratio machining.
Mitra, Sambit; Chanal, Margaux; Clady, Raphaël; Mouskeftaras, Alexandros; Grojo, David
2015-08-20
We report on a functional experimental design for Bessel beam generation capable of handling high-energy ultrashort pulses (up to 1.2 mJ per pulse of 50 fs duration). This allows us to deliver intensities exceeding the breakdown threshold for air or any dielectric along controlled micro-filaments with lengths exceeding 4 mm. It represents an unprecedented upscaling in comparison to recent femtosecond Bessel beam micromachining experiments. We produce void microchannels through glass substrates to demonstrate that aspect ratios exceeding 1200∶1 can be achieved by using single high-intensity pulses. This demonstration must lead to new methodologies for deep-drilling and high-speed cutting applications.
Ultra-high aspect ratio replaceable AFM tips using deformation-suppressed focused ion beam milling
DEFF Research Database (Denmark)
Savenko, Alexey; Yildiz, Izzet; Petersen, Dirch Hjorth;
2013-01-01
in terms of defining the shape and size of the tip. Due to beam-induced deformation, it has so far not been possible to define HAR structures using lateral FIB milling. In this work we obtain aspect ratios of up to 45, with tip diameters down to 9 nm, by a deformation-suppressing writing strategy. Several...... FIB milling strategies for obtaining sharper tips are discussed. Finally, assembly of the HAR tips on a custom-designed probe as well as the first AFM scanning is shown....
DARHT-II Long-Pulse Beam-Dynamics Experiments
Ekdahl, Carl; Bartsch, Richard; Bender, Howard; Briggs, Richard J; Broste, William; Carlson, Carl; Caudill, Larry; Chan, Kwok-Chi D; Chen Yu Jiuan; Dalmas, Dale; Durtschi, Grant; Eversole, Steven; Eylon, Shmuel; Fawley, William M; Frayer, Daniel; Gallegos, Robert J; Harrison, James; Henestroza, Enrique; Holzscheiter, M H; Houck, Timothy L; Hughes, Thomas P; Jacquez, Edward; Johnson, Douglas; Johnson, Jeffrey; Jones, Kenneth; McCuistian, Brian T; Meidinger, Alfred; Montoya, Nicholas; Mostrom, Chris; Moy, Kenneth; Nath, Subrata; Nielsen, Kurt; Oro, David; Rodriguez, Leroy; Rodriguez, Patrick; Rowton, Larry J; Sanchez, Manolito; Scarpetti, Raymond; Schauer, Martin; Schulze, Martin E; Simmons, David; Studebaker, Jan; Sturgess, Ronald; Sullivan, Gary; Swinney, Charles; Tang, Yan; Temple, Rodney; Tipton, Angela; Tom, C Y; Vernon Smith, H; Yu, Simon
2005-01-01
When completed, the DARHT-II linear induction accelerator (LIA) will produce a 2-kA, 18-MeV electron beam with more than 1500-ns current/energy "flat-top." In initial tests DARHT-II has already accelerated beams with current pulse lengths from 500-ns to 1200-ns full-width at half maximum (FWHM) with more than1.2-kA, 12.5-MeV peak current and energy. Experiments are now underway with a ~2000-ns pulse length, but reduced current and energy. These pulse lengths are all significantly longer than any other multi-MeV LIA, and they define a novel regime for high-current beam dynamics, especially with regard to beam stability. Although the initial tests demonstrated absence of BBU, the pulse lengths were too short to test the predicted protection against ion-hose instability. The present experiments are designed to resolve these and other beam-dynamics issues with a ~2000-ns pulse length beam.
Dense high aspect ratio hydrogen silsesquioxane nanostructures by 100 keV electron beam lithography
Energy Technology Data Exchange (ETDEWEB)
Vila-Comamala, Joan; Gorelick, Sergey; Guzenko, Vitaliy A; David, Christian [Paul Scherrer Institut, Villigen CH-5232 (Switzerland); Faerm, Elina; Ritala, Mikko, E-mail: joan.vila@psi.ch [Department of Chemistry, University of Helsinki, Helsinki FI-00014 (Finland)
2010-07-16
We investigated the fabrication of dense, high aspect ratio hydrogen silsesquioxane (HSQ) nanostructures by 100 keV electron beam lithography. The samples were developed using a high contrast developer and supercritically dried in carbon dioxide. Dense gratings with line widths down to 25 nm were patterned in 500 nm-thick resist layers and semi-dense gratings with line widths down to 10 nm (40 nm pitch) were patterned in 250 nm-thick resist layers. The dense HSQ nanostructures were used as molds for gold electrodeposition, and the semi-dense HSQ gratings were iridium-coated by atomic layer deposition. We used these methods to produce Fresnel zone plates with extreme aspect ratio for scanning transmission x-ray microscopy that showed excellent performance at 1.0 keV photon energy.
Dense high aspect ratio hydrogen silsesquioxane nanostructures by 100 keV electron beam lithography
Vila-Comamala, Joan; Gorelick, Sergey; Guzenko, Vitaliy A.; Färm, Elina; Ritala, Mikko; David, Christian
2010-07-01
We investigated the fabrication of dense, high aspect ratio hydrogen silsesquioxane (HSQ) nanostructures by 100 keV electron beam lithography. The samples were developed using a high contrast developer and supercritically dried in carbon dioxide. Dense gratings with line widths down to 25 nm were patterned in 500 nm-thick resist layers and semi-dense gratings with line widths down to 10 nm (40 nm pitch) were patterned in 250 nm-thick resist layers. The dense HSQ nanostructures were used as molds for gold electrodeposition, and the semi-dense HSQ gratings were iridium-coated by atomic layer deposition. We used these methods to produce Fresnel zone plates with extreme aspect ratio for scanning transmission x-ray microscopy that showed excellent performance at 1.0 keV photon energy.
Kikuchi, Takashi; Katayama, Takeshi; Kawata, Shigeo; Nakajima, Mitsuo; Someya, Tetsuo
2005-01-01
Beam dynamics is investigated by multi-particle simulations during a final beam bunching in a driver system for heavy ion inertial fusion (HIF). The longitudinal bunch compression causes the beam instability induced by the strong space charge effect. The multi-particle simulation can indicate the emittance growth due to the longitudinal bunch compression. Dependence in the beam pulse duration is also investigated for effective pellet implosion in HIF. Not only the spatial nonuniformity of the beam illumination, but also the errors of the beam pulse duration cause changes of implosion dynamics. The allowable regime of the beam pulse duration for the effective fusion output becomes narrow with decreasing the input beam energy. The voltage accuracy requirement at the beam velocity modulator is also estimated for the final beam bunching. It is estimated that the integrated voltage error is allowable as a few percent.
Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators
Energy Technology Data Exchange (ETDEWEB)
Mastoridis, Themistoklis [Stanford Univ., CA (United States)
2010-08-01
The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC
Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators
International Nuclear Information System (INIS)
The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC
Dynamical deformed Airy beams with arbitrary angles between two wings.
Liang, Yi; Hu, Yi; Ye, Zhuoyi; Song, Daohong; Lou, Cibo; Zhang, Xinzheng; Xu, Jingjun; Morandotti, Roberto; Chen, Zhigang
2014-07-01
We study both numerically and experimentally the acceleration and propagation dynamics of 2D Airy beams with arbitrary initial angles between their "two wings." Our results show that the acceleration of these generalized 2D Airy beams strongly depends on the initial angles and cannot be simply described by the vector superposition principle (except for the normal case of a 90° angle). However, as a result of the "Hyperbolic umbilic" catastrophe (a two-layer caustic), the main lobes of these 2D Airy beams still propagate along parabolic trajectories even though they become highly deformed. Under such conditions, the peak intensity (leading energy flow) of the 2D Airy beams cannot be confined along the main lobe, in contrast to the normal 90° case. Instead, it is found that there are two parabolic trajectories describing the beam propagation: one for the main lobe, and the other for the peak intensity. Both trajectories can be readily controlled by varying the initial wing angle. Due to their self-healing property, these beams tend to evolve into the well-known 1D or 2D Airy patterns after a certain propagation distance. The theoretical analysis corroborates our experimental observations, and explains clearly why the acceleration of deformed Airy beams increases with the opening of the initial wing angle. PMID:25121433
Spatial-temporal dynamics of broadband terahertz Bessel beam propagation
Semenova, V. A.; Kulya, M. S.; Bespalov, V. G.
2016-08-01
The unique properties of narrowband and broadband terahertz Bessel beams have led to a number of their applications in different fields, for example, for the depth of focusing and resolution enhancement in terahertz imaging. However, broadband terahertz Bessel beams can probably be also used for the diffraction minimization in the short-range broadband terahertz communications. For this purpose, the study of spatial-temporal dynamics of the broadband terahertz Bessel beams is needed. Here we present a simulation-based study of the propagating in non-dispersive medium broadband Bessel beams generated by a conical axicon lens. The algorithm based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the Bessel beam in the frequency range from 0.1 to 3 THz at the distances 10-200 mm from the axicon. Bessel beam field is studied for the different spectral components of the initial pulse. The simulation results show that for the given parameters of the axicon lens one can obtain the Gauss-Bessel beam generation in the spectral range from 0.1 to 3 THz. The length of non-diffraction propagation for a different spectral components was measured, and it was shown that for all spectral components of the initial pulse this length is about 130 mm.
Cold atom dynamics in crossed laser beam waveguides
Torrontegui, E; Ruschhaupt, A; Guéry-Odelin, D; Muga, J G
2010-01-01
We study the dynamics of neutral cold atoms in an $L$-shaped crossed-beam optical waveguide formed by two perpendicular red-detuned lasers of different intensities and a blue-detuned laser at the corner. Complemented with a vibrational cooling process this setting works as a one-way device or "atom diode".
Quasiclassical Calculations of Wigner Functions in Nonlinear Beam Dynamics
Fedorova, A N; Fedorova, Antonina N.; Zeitlin, Michael G.
2001-01-01
We present the application of variational-wavelet analysis to numerical/analytical calculations of Wigner functions in (nonlinear) quasiclassical beam dynamics problems. (Naive) deformation quantization and multiresolution representations are the key points. We construct the representation via multiscale expansions in generalized coherent states or high-localized nonlinear eigenmodes in the base of compactly supported wavelets and wavelet packets.
Evaluating the Dynamic Characteristics of Retrofitted RC Beams
Ghods, Amir S.; Esfahani, Mohamad R.; Moghaddasie, Behrang
2008-07-01
The aim of this experimental study was to investigate the relationship between the damage and changes in dynamic characteristics of reinforced concrete members strengthened with Carbon Fiber Reinforced Polymer (CFRP). Modal analysis is a popular non-destructive method for evaluating health of structural systems. A total of 8 reinforced concrete beams with similar dimensions were made using concrete with two different compressive strengths and reinforcement ratios. Monotonic loading was applied with four-point-bending setup in order to generate different damage levels in the specimens while dynamic testing was conducted to monitor the changes in dynamic characteristics of the specimens. In order to investigate the effect of CFRP on static and dynamic properties of specimens, some of the beams were loaded to half of their ultimate load carrying capacity and then were retrofitted using composite laminates with different configuration. Retrofitted specimens demonstrated elevated load carrying capacity, higher flexural stiffness and lower displacement ductility. By increasing the damage level in specimens, frequencies of the beams were decreased and after strengthening these values were improved significantly. The intensity of the damage level in each specimen affects the shape of its mode as well. Fixed points and curvatures of mode shapes of beams tend to move toward the location of the damage in each case.
Evaluating the Dynamic Characteristics of Retrofitted RC Beams
International Nuclear Information System (INIS)
The aim of this experimental study was to investigate the relationship between the damage and changes in dynamic characteristics of reinforced concrete members strengthened with Carbon Fiber Reinforced Polymer (CFRP). Modal analysis is a popular non-destructive method for evaluating health of structural systems. A total of 8 reinforced concrete beams with similar dimensions were made using concrete with two different compressive strengths and reinforcement ratios. Monotonic loading was applied with four-point-bending setup in order to generate different damage levels in the specimens while dynamic testing was conducted to monitor the changes in dynamic characteristics of the specimens. In order to investigate the effect of CFRP on static and dynamic properties of specimens, some of the beams were loaded to half of their ultimate load carrying capacity and then were retrofitted using composite laminates with different configuration. Retrofitted specimens demonstrated elevated load carrying capacity, higher flexural stiffness and lower displacement ductility. By increasing the damage level in specimens, frequencies of the beams were decreased and after strengthening these values were improved significantly. The intensity of the damage level in each specimen affects the shape of its mode as well. Fixed points and curvatures of mode shapes of beams tend to move toward the location of the damage in each case
An rf separated kaon beam from the Main Injector: Superconducting aspects
Energy Technology Data Exchange (ETDEWEB)
D.A. Edwards
1998-11-01
ThE report is intended to focus on the superconducting aspects of a potential separated kaon beam facility for the Main Injector, and most of this document reflects that emphasis. However, the RF features cannot be divorced from the overall beam requirements, and so the next section is devoted to the latter subject. The existing optics design that meets the needs of the two proposed experiments is outliied, and its layout at Fermilab is shown. The frequency and deflection gradient choices present implementation dMiculties, and the section closes with some commentary on these issues. Sec. 3 provides an introduction to cavity design considerations, and, in particular carries forward the discussion of resonator shape and frequency selection. The R&D program is the subject of Sec. 4. Provisional parameter choices will be summarized. Initial steps toward cavity fabrication based `on copper models have been taken. The next stages in cavity fabrication will be reviewed in some detail. The infrastructure needs and availability will be discussed. Sec. 5 discusses what maybe characterized as the in~edlents of a point design. At this writing, some aspects are clear and some are not. The basic systems are reasonably clear and are described. The final section presents a cost and schedule estimate for both the Ft&D and production phase. Some supporting material and elaboration is provided in the Appendices.
The analysis of technical and economical aspects of electron beam flue gas treatment
International Nuclear Information System (INIS)
Environmental problems caused by the increased world energy demands have become a serious problem in many countries. The emission of SO2 and NOx from fossil fuel burning for electricity generation and industrial plants is one of the major sources of environmental pollution. These pollutants are named as acid gases causing acid rain and also indirect greenhouse gases contributing greenhouse effect. These toxic components sometimes travel more than thousand kilometers and make a trouble in other places, in some cases, even in other countries. Therefore, the problem of the air pollution became world-wide problem. Today many countries are introducing more strict emission control regulations to solve environmental problem. Electron beam flue gas treatment technology is one of the most advanced technologies among new generation processes for air pollution control. This electron beam process is dry scrubbing process and simultaneously removes SO2 and NOx and useful by-product for agriculture fertilizer. In this study, the technical and economical aspects of electron beam flue gas treatment process are discussed. Economically, the technology is competitive with the conventional ones. (author)
Online optimization of storage ring nonlinear beam dynamics
Huang, Xiaobiao
2015-01-01
We propose to optimize the nonlinear beam dynamics of existing and future storage rings with direct online optimization techniques. This approach may have crucial importance for the implementation of diffraction limited storage rings. In this paper considerations and algorithms for the online optimization approach are discussed. We have applied this approach to experimentally improve the dynamic aperture of the SPEAR3 storage ring with the robust conjugate direction search method and the particle swarm optimization method. The dynamic aperture was improved by more than 5 mm within a short period of time. Experimental setup and results are presented.
Lifschitz, A. F.; Maynard, G.; Vay, J.-L.; Lenglet, A.
2006-06-01
The efficiency of a Heavy Ion Fusion reactor heavily depends on the maximum value for the density of energy (DoE) that can be deposited by the ion beams. In order to reduce the final radius, and thus to increase the DoE inside the target, the beam spatial charge has to be neutralized. Therefore the dynamics of the neutralizing electrons (DNE) play a central role in optimizing the DoE deposited in solid targets by high current of high energy heavy ion beams. We present results on some aspects of the DNE, which was performed using the Monte-Carlo 2D1/2 PIC code BPIC.
Non Linear Beam Dynamics Studies at SPEAR
International Nuclear Information System (INIS)
The frequency map analysis of a Hamiltonian system recently introduced to accelerators physics in combination with turn-by-turn phase space measurements opens new experimental opportunities for studying non linear dynamic in storage rings. In this paper we report on the experimental program at SPEAR having the goal of measuring the frequency map of the machine. In this paper we discuss the accuracy of the instantaneous tune extraction from experimental data and demonstrate the possibility of the frequency map measurement. The instantaneous tune extraction technique can be applied to experimental tracking data with reasonable accuracy. Frequency map can be experimentally determined using the existing turn-by-turn phase space measurement techniques and NAFF instantaneous tune extraction.
Dynamic aspects of radioactive contamination of marine organisms
International Nuclear Information System (INIS)
The report consists of three parts. The first part addresses the kinetics of bioconcentration of chemicals in an aquatic ecosystem. Exponential models are discussed to describe the dynamic aspects of movement (bioconcentration) of a chemical in an aquatic ecosystem. Differential equations for a two-compartment model are solved to relate the movement of a material between fish and water. Similar integrated equations are derived for a three-compartment model. Explanations are made in relation to the concept of the models, their limitations in application to real ecosystems and bioconcentration factors. The second part deals with sea water exchange. The second reprocessing plant in Japan is being planned to be operational in 1955. A new model is now under development by CRIEPI. For the near-field sea area, a three-dimensional model is applied for predicting the three-dimensional behavior of nuclides. In the far-field area, a two-dimensional model is applied. The two- and three-dimensional models are interfaced to produce a combined model. The third part addresses the field-laboratory aomparability. A study is made to estimate the concentration of radionuclides in organisms applying an exponential model which involves the reduction coefficient of radioactivity in sea water together with other biological parameters. The model is successfully applied to the reduction of 60Co with time in brown algae. (N.K.)
Quantitative high dynamic range beam profiling for fluorescence microscopy
Energy Technology Data Exchange (ETDEWEB)
Mitchell, T. J., E-mail: t.j.mitchell@dur.ac.uk; Saunter, C. D.; O’Nions, W.; Girkin, J. M.; Love, G. D. [Centre for Advanced Instrumentation and Biophysical Sciences Institute, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)
2014-10-15
Modern developmental biology relies on optically sectioning fluorescence microscope techniques to produce non-destructive in vivo images of developing specimens at high resolution in three dimensions. As optimal performance of these techniques is reliant on the three-dimensional (3D) intensity profile of the illumination employed, the ability to directly record and analyze these profiles is of great use to the fluorescence microscopist or instrument builder. Though excitation beam profiles can be measured indirectly using a sample of fluorescent beads and recording the emission along the microscope detection path, we demonstrate an alternative approach where a miniature camera sensor is used directly within the illumination beam. Measurements taken using our approach are solely concerned with the illumination optics as the detection optics are not involved. We present a miniature beam profiling device and high dynamic range flux reconstruction algorithm that together are capable of accurately reproducing quantitative 3D flux maps over a large focal volume. Performance of this beam profiling system is verified within an optical test bench and demonstrated for fluorescence microscopy by profiling the low NA illumination beam of a single plane illumination microscope. The generality and success of this approach showcases a widely flexible beam amplitude diagnostic tool for use within the life sciences.
Mathematical and Numerical Methods for Non-linear Beam Dynamics
Herr, W
2014-01-01
Non-linear effects in accelerator physics are important for both successful operation of accelerators and during the design stage. Since both of these aspects are closely related, they will be treated together in this overview. Some of the most important aspects are well described by methods established in other areas of physics and mathematics. The treatment will be focused on the problems in accelerators used for particle physics experiments. Although the main emphasis will be on accelerator physics issues, some of the aspects of more general interest will be discussed. In particular, we demonstrate that in recent years a framework has been built to handle the complex problems in a consistent form, technically superior and conceptually simpler than the traditional techniques. The need to understand the stability of particle beams has substantially contributed to the development of new techniques and is an important source of examples which can be verified experimentally. Unfortunately, the documentation of ...
Beam dynamics of CANDLE storage ring low alpha operation
Sargsyan, A.; Amatuni, G.; Sahakyan, V.; Tsakanov, V.; Zanyan, G.
2015-10-01
The generation of the coherent THz radiation and short pulse synchrotron radiation in dedicated electron storage rings requires the study of non-standard magnetic lattices which provide low momentum compaction factor (alpha) of the ring. In the present paper two low alpha operation lattices based on modification of the original beam optics and implementation of inverse bend magnets are studied for CANDLE storage ring. For considered cases an analysis of transverse and longitudinal beam dynamics is given and the feasibility of lattices is discussed.
Beam dynamics of CANDLE storage ring low alpha operation
International Nuclear Information System (INIS)
The generation of the coherent THz radiation and short pulse synchrotron radiation in dedicated electron storage rings requires the study of non-standard magnetic lattices which provide low momentum compaction factor (alpha) of the ring. In the present paper two low alpha operation lattices based on modification of the original beam optics and implementation of inverse bend magnets are studied for CANDLE storage ring. For considered cases an analysis of transverse and longitudinal beam dynamics is given and the feasibility of lattices is discussed
Beam dynamics studies in a tesla positron pre-accelerator
Moiseev, V A; Flöttmann, K
2001-01-01
The TESLA linear collider is based on superconducting accelerating cavities.Behind the positron production target normal conducting cavities have to be used in order to cope with high particle losses and with focusing solenoid surrounding the cavities.The main purpose of this pre-accelerator is to provide maximum capture efficiency for the useful part of the totally acceptable positron beam with technically reasonable parameters of the linac.The coupled optimization of the capture optics behind the target and pre-accelerator rf-operation has been carried out.The beam dynamics simulation results as well as the pre-accelerator peculiarities are presented.
Longitudinal beam dynamics for heavy ion fusion using WARPrz
International Nuclear Information System (INIS)
WARPrz is a 2.5 dimensional, cylindrically symmetric, electrostatic, particle-in-cell code. It is part of the WARP family of codes which has been developed to study heavy ion fusion driver issues. WARPrz is being used to study the longitudinal dynamics of heavy ion beams including a longitudinal instability that is driven by the impedance of the LINAC accelerating modules. This instability is of concern because it can enhance longitudinal momentum spread; chromatic abhoration in the lens system restricts the amount of momentum spread allowed in the beam in the final focusing system. The impedance of the modules is modeled by a continuum of resistors and capacitors in parallel in WARPrz. We discuss simulations of this instability including the effect of finite temperature and reflection of perturbations off the beam ends. We also discuss intermittency of axial confining fields (''ears'' fields) as a seed for this instability
Beam dynamics design for uranium drift tube linear accelerator
Dou, Wei-Ping; He, Yuan; Lu, Yuan-Rong
2014-07-01
KONUS beam dynamics design of uranium DTL with LORASR code is presented. The 238U34+ beam, whose current is 5.0 emA, is accelerated from injection energy of 0.35 MeV/u to output energy of 1.30 MeV/u by IH-DTL operated at 81.25 MHz in HIAF project at IMP of CAS. It achieves a transmission efficiency of 94.95% with a cavity length of 267.8 cm. The optimization aims are the reduction of emittance growth, beam loss and project costs. Because of the requirements of CW mode operation, the designed average acceleration gradient is about 2.48 MV/m. The maximum axial field is 10.2 MV/m, meanwhile the Kilpatrick breakdown field is 10.56 MV/m at 81.25 MHz.
KONUS Beam Dynamics Design of Uranium DTL for HIAF
Dou, W P; Lu, Y R
2013-01-01
KONUS beam dynamics design of uranium DTL with LORASR code is presented. The 238U34+ beam, whose current is 5.0emA, is accelerated from injection energy of 0.35MeV/u to output energy of 1.3MeV/u by IH-DTL operated at 81.25MHz in HIAF project at IMP of CAS. It achieves transmission efficiency of 94.95% with the cavity length 267.8cm. Optimization aims are the reduction of emittance growth, of beam loss and of project costs. Because of the requirements of CW mode operation,the designed average acceleration gradient is about 2.48MV/m. Maximum axial filed is 10.2MV/m, meanwhile Kilpatrick breakdown field is 10.56MV/m at 81.25MHz.
Beam dynamics in rf guns and emittance correction techniques
Serafini, Luca
1994-02-01
In this paper we present a general review of beam dynamics in a laser-driven rf gun. The peculiarity of such an accelerating structure versus other conventional multi-cell linac structures is underlined on the basis of the Panofsky-Wenzel theorem, which is found to give a theoretical background for the well known Kim's model. A basic explanation for some proposed methods to correct rf induced emittance growth is also derived from the theorem. We also present three emittance correction techniques for the recovery of space-charge induced emittance growth, namely the optimum distributed disk-like bunch technique, the use of rf spatial harmonics to correct spherical aberration induced by space charge forces and the technique of emittance filtering by clipping the electron beam. The expected performances regarding the beam quality achievable with different techniques, as predicted by scaling laws and simulations, are analyzed, and, where available, compared to experimental results.
Student Youth: Dynamics of Political Interests (Regional Aspect
Directory of Open Access Journals (Sweden)
Morozova Galina Viktorovna
2015-12-01
Full Text Available The article presents the main results of the research of interests and political orientations of student youth which was carried out in 2014 at the Kazan federal university and its branches in the territory of the Republic of Tatarstan. The choice of student youth as a reference group is caused by a number of factors, among which we should name the status of intellectual elite, social and political mobility that allows to consider students as the potential actors of socio-political transformations in the country. The data obtained during poll compared with the results of last research allow defining the dynamics of development of student youth’s political sentiment in the region. The study of political attitudes, preferences of students was based on the identification of a number of indicators (degree of interest in politics, the level of personal involvement in political life and on the study of factors that determine the motivation of political behavior of students. Empirical studies make it possible to rank the problems that dominate the political consciousness of students in the region. These include a high level of corruption in the government, inflation, rising prices, the state of health and education systems and the growing income inequality. Particular attention is accented on the problems associated with the foreign policy aspects, threats, aggression from abroad. The study showed that most young people’s interest in politics is limited primarily by informational level, rarely they have desire to express their own position or judgments in political situations. The level of real political participation, socio-political activity of students is low. Obtained results let us notice the increasing trend of demonstration of protest behavior among certain part of the students.
Beam dynamics of alternating-phase-focused linac
Iwata, Y; Kapin, V
2004-01-01
A simple method to find an array of synchronous phases for alternating-phase-focused (APF) linacs is presented. The phase array is described with a smooth function having free parameters. With a set of the parameters, a simulation on the beam dynamics was made and distributions of the six-dimensional phase spaces were calculated for each set of the parameters. The parameters were varied, and numbers of the simulations have been performed. An optimum set of the parameters were determined so that the simulations of the beam dynamics yield large acceptances and small emittances of the extracted beams. Since the APF linac can provide both axial and radial stability of beams just with the rf acceleration-field, no additional focusing element inside of drift tubes are necessary. Comparing with conventional linacs having focusing elements, it has advantage in construction and operation costs as well as its acceleration rate. Therefore, the APF linacs would be suited for an injector of medical synchrotrons. A practic...
Dynamics and transport of laser-accelerated particle beams
Energy Technology Data Exchange (ETDEWEB)
Becker, Stefan
2010-04-19
The subject of this thesis is the investigation and optimization of beam transport elements in the context of the steadily growing field of laser-driven particle acceleration. The first topic is the examination of the free vacuum expansion of an electron beam at high current density. It could be shown that particle tracking codes which are commonly used for the calculation of space charge effects will generate substantial artifacts in the regime considered here. The artifacts occurring hitherto predominantly involve insufficient prerequisites for the Lorentz transformation, the application of inadequate initial conditions and non negligible retardation artifacts. A part of this thesis is dedicated to the development of a calculation approach which uses a more adequate ansatz calculating space charge effects for laser-accelerated electron beams. It can also be used to validate further approaches for the calculation of space charge effects. The next elements considered are miniature magnetic quadrupole devices for the focusing of charged particle beams. General problems involved with their miniaturization concern distorting higher order field components. If these distorting components cannot be controlled, the field of applications is very limited. In this thesis a new method for the characterization and compensation of the distorting components was developed, which might become a standard method when assembling these permanent magnet multipole devices. The newly developed characterization method has been validated at the Mainz Microtron (MAMI) electron accelerator. Now that we can ensure optimum performance, the first application of permanent magnet quadrupole devices in conjunction with laser-accelerated ion beams is presented. The experiment was carried out at the Z-Petawatt laser system at Sandia National Laboratories. A promising application for laser-accelerated electron beams is the FEL in a university-scale size. The first discussion of all relevant aspects
Space-charge dynamics of polymethylmethacrylate under electron beam irradiation
Gong, H; Ong, C K
1997-01-01
Space-charge dynamics of polymethylmethacrylate (PMMA) under electron beam irradiation has been investigated employing a scanning electron microscope. Assuming a Gaussian space-charge distribution, the distribution range (sigma) has been determined using a time-resolved current method in conjunction with a mirror image method. sigma is found to increase with irradiation time and eventually attain a stationary value. These observations have been discussed by taking into account radiation-induced conductivity and charge mobility. (author)
Dynamics of fast charged particle beam rotation in bended crystals
International Nuclear Information System (INIS)
Dynamics of fast charged particle beam rotation in a bended monocrystal is considered. Face and volume mechanisms of capture in channels are taken into account simultaneously in the model presented. Functions of distribution in transverse energies (φ) of channeled and dechanneled particles are obtained. Charge-energy ''scale invariance'' in ion channeling with charge Z in a bended crystal determined by scale parameter W=pv/Z (p and v are pulse and velocity local to transverse planes) follows from the model presented
Some topics in beam dynamics of storage rings
International Nuclear Information System (INIS)
In the following report we want to review some beam dynamics problems in accelerator physics. Theoretical tools and methods are introduced and discussed, and it is shown how these concepts can be applied to the study of various problems in storage rings. The first part treats Hamiltonian systems (proton accelerators) whereas the second part is concerned with explicitly stochastic systems (e.g. electron storage rings). (orig.)
Study of longitudinal dynamics in space-charge dominated beams
Tian, Kai
Modern accelerator applications, such as heavy ion fusion drivers, pulsed neutron sources, electron injectors for high-energy linear colliders, and X-ray Free Electron Lasers, demand beams with high intensity, low emittance and small energy spread. At low (non-relativistic) energies, the "electrostatic", collective interactions from space-charge forces existing in such intense beams play the dominant role; we characterize these beams as space-charge dominated beams. This dissertation presents numerous new findings on the longitudinal dynamics of a space-charge dominated beam, particularly on the propagation of density perturbations. In order to fully understand the complex physics of longitudinal space-charge waves, we combine the results of theory, computer simulation, and experiment. In the Long Solenoid Experimental system (LSE), with numerous diagnostic tools and techniques, we have, for the first time, experimentally measured the detailed energy profiles of longitudinal space-charge waves at different locations, both near the beam source and at the end of the transport system. Along with the current profiles, we have a complete set of experimental data for the propagation of space-charge waves. We compare these measured results to a 1-D theory and find better agreement for beams with perturbations in the linear regime, where the perturbation strength is less than 10%, than those with nonlinear perturbations. Using fast imaging techniques that we newly developed, we have, for the first time, obtained the progressive time-resolved images of longitudinal slices of a space-charge dominated beam. These images not only provide us time-resolved transverse density distribution of the beam, but also enable us to take time-resolved transverse phase space measurement using computerized tomography. By combining this information with the longitudinal energy measurement, we have, for the first time, experimentally constructed the full 6-D phase space. Part of the results
Nonlinear Dynamical analysis of an AFM tapping mode microcantilever beam
Directory of Open Access Journals (Sweden)
Choura S.
2012-07-01
Full Text Available We focus in this paper on the modeling and dynamical analysis of a tapping mode atomic force microscopy (AFM microcantilever beam. This latter is subjected to a harmonic excitation of its base displacement and to Van der Waals and DMT contact forces at its free end. For AFM design purposes, we derive a mathematical model for accurate description of the AFM microbeam dynamics. We solve the resulting equations of motions and associated boundary conditions using the Galerkin method. We find that using one-mode approximation in tapping mode operating in the neighborhood of the contact region one-mode approximation may lead to erroneous results.
Investigations of the Dynamics of Space Charged Dominated Beams
Energy Technology Data Exchange (ETDEWEB)
York, Richard C.
2002-08-01
We propose to perform investigations of the dynamics of space charge dominated beams. These investigations will support present activities such as the electron ring project at the University of Maryland as well as provide an improved basis for future accelerator designs. Computer simulations will provide the primary research element with improved code development being an integral part of the activities during the first period. We believe that one of the code development projects provides a unique strategy for the inclusion of longitudinal dynamics, and that this concept should provide a computationally rapid research tool.
Environmental colour affects aspects of single-species population dynamics.
Petchey, O L
2000-01-01
Single-species populations of ciliates (Colpidium and Paramecium) experienced constant temperature or white or reddened temperature fluctuations in aquatic microcosms in order to test three hypotheses about how environmental colour influences population dynamics. (i) Models predict that the colour of population dynamics is tinged by the colour of the environmental variability. However, environmental colour had no effect on the colour of population dynamics. All population dynamics in this exp...
Chaotic dynamics of flexible Euler-Bernoulli beams.
Awrejcewicz, J; Krysko, A V; Kutepov, I E; Zagniboroda, N A; Dobriyan, V; Krysko, V A
2013-12-01
Mathematical modeling and analysis of spatio-temporal chaotic dynamics of flexible simple and curved Euler-Bernoulli beams are carried out. The Kármán-type geometric non-linearity is considered. Algorithms reducing partial differential equations which govern the dynamics of studied objects and associated boundary value problems are reduced to the Cauchy problem through both Finite Difference Method with the approximation of O(c(2)) and Finite Element Method. The obtained Cauchy problem is solved via the fourth and sixth-order Runge-Kutta methods. Validity and reliability of the results are rigorously discussed. Analysis of the chaotic dynamics of flexible Euler-Bernoulli beams for a series of boundary conditions is carried out with the help of the qualitative theory of differential equations. We analyze time histories, phase and modal portraits, autocorrelation functions, the Poincaré and pseudo-Poincaré maps, signs of the first four Lyapunov exponents, as well as the compression factor of the phase volume of an attractor. A novel scenario of transition from periodicity to chaos is obtained, and a transition from chaos to hyper-chaos is illustrated. In particular, we study and explain the phenomenon of transition from symmetric to asymmetric vibrations. Vibration-type charts are given regarding two control parameters: amplitude q(0) and frequency ω(p) of the uniformly distributed periodic excitation. Furthermore, we detected and illustrated how the so called temporal-space chaos is developed following the transition from regular to chaotic system dynamics.
Dynamic bowtie filter for cone-beam/multi-slice CT.
Directory of Open Access Journals (Sweden)
Fenglin Liu
Full Text Available A pre-patient attenuator ("bowtie filter" or "bowtie" is used to modulate an incoming x-ray beam as a function of the angle of the x-ray with respect to a patient to balance the photon flux on a detector array. While the current dynamic bowtie design is focused on fan-beam geometry, in this study we propose a methodology for dynamic bowtie design in multi-slice/cone-beam geometry. The proposed 3D dynamic bowtie is an extension of the 2D prior art. The 3D bowtie consists of a highly attenuating bowtie (HB filled in with heavy liquid and a weakly attenuating bowtie (WB immersed in the liquid of the HB. The HB targets a balanced flux distribution on a detector array when no object is in the field of view (FOV. The WB compensates for an object in the FOV, and hence is a scaled-down version of the object. The WB is rotated and translated in synchrony with the source rotation and patient translation so that the overall flux balance is maintained on the detector array. First, the mathematical models of different scanning modes are established for an elliptical water phantom. Then, a numerical simulation study is performed to compare the performance of the scanning modes in the cases of the water phantom and a patient cross-section without any bowtie and with a dynamic bowtie. The dynamic bowtie can equalize the numbers of detected photons in the case of the water phantom. In practical cases, the dynamic bowtie can effectively reduce the dynamic range of detected signals inside the FOV. Furthermore, the WB can be individualized using a 3D printing technique as the gold standard. We have extended the dynamic bowtie concept from 2D to 3D by using highly attenuating liquid and moving a scale-reduced negative copy of an object being scanned. Our methodology can be applied to reduce radiation dose and facilitate photon-counting detection.
Dynamic bowtie filter for cone-beam/multi-slice CT.
Liu, Fenglin; Yang, Qingsong; Cong, Wenxiang; Wang, Ge
2014-01-01
A pre-patient attenuator ("bowtie filter" or "bowtie") is used to modulate an incoming x-ray beam as a function of the angle of the x-ray with respect to a patient to balance the photon flux on a detector array. While the current dynamic bowtie design is focused on fan-beam geometry, in this study we propose a methodology for dynamic bowtie design in multi-slice/cone-beam geometry. The proposed 3D dynamic bowtie is an extension of the 2D prior art. The 3D bowtie consists of a highly attenuating bowtie (HB) filled in with heavy liquid and a weakly attenuating bowtie (WB) immersed in the liquid of the HB. The HB targets a balanced flux distribution on a detector array when no object is in the field of view (FOV). The WB compensates for an object in the FOV, and hence is a scaled-down version of the object. The WB is rotated and translated in synchrony with the source rotation and patient translation so that the overall flux balance is maintained on the detector array. First, the mathematical models of different scanning modes are established for an elliptical water phantom. Then, a numerical simulation study is performed to compare the performance of the scanning modes in the cases of the water phantom and a patient cross-section without any bowtie and with a dynamic bowtie. The dynamic bowtie can equalize the numbers of detected photons in the case of the water phantom. In practical cases, the dynamic bowtie can effectively reduce the dynamic range of detected signals inside the FOV. Furthermore, the WB can be individualized using a 3D printing technique as the gold standard. We have extended the dynamic bowtie concept from 2D to 3D by using highly attenuating liquid and moving a scale-reduced negative copy of an object being scanned. Our methodology can be applied to reduce radiation dose and facilitate photon-counting detection. PMID:25051067
Lie Algebraic Treatment of Linear and Nonlinear Beam Dynamics
Energy Technology Data Exchange (ETDEWEB)
Alex J. Dragt; Filippo Neri; Govindan Rangarajan; David Douglas; Liam M. Healy; Robert D. Ryne
1988-12-01
The purpose of this paper is to present a summary of new methods, employing Lie algebraic tools, for characterizing beam dynamics in charged-particle optical systems. These methods are applicable to accelerator design, charged-particle beam transport, electron microscopes, and also light optics. The new methods represent the action of each separate element of a compound optical system, including all departures from paraxial optics, by a certain operator. The operators for the various elements can then be concatenated, following well-defined rules, to obtain a resultant operator that characterizes the entire system. This paper deals mostly with accelerator design and charged-particle beam transport. The application of Lie algebraic methods to light optics and electron microscopes is described elsewhere (1, see also 44). To keep its scope within reasonable bounds, they restrict their treatment of accelerator design and charged-particle beam transport primarily to the use of Lie algebraic methods for the description of particle orbits in terms of transfer maps. There are other Lie algebraic or related approaches to accelerator problems that the reader may find of interest (2). For a general discussion of linear and nonlinear problems in accelerator physics see (3).
Implementation of geometrically exact beam element for nonlinear dynamics modeling
Energy Technology Data Exchange (ETDEWEB)
Wang, Jielong, E-mail: jelon.wang@gmail.com [Commercial Aircraft Corporation of China, Ltd., Beijing Aeronautical Science & Technology Research Institute (China)
2015-12-15
The paper develops a new type of geometrically exact beam element featuring large displacements and rotations together with small warping. The dimension reduction approach based on variational asymptotic method has been explored, and a linear two-dimensional finite element procedure has been implemented to predict the cross-sectional stiffness and recover the cross-sectional strain fields of the beam. The total and incremental variables mixed formula of governing equations of motion is presented, in which the Wiener–Milenković parameters are selected to vectorize the finite rotation. The dynamic problem of geometrically exact beam has been solved by the implicit Radau IIA algorithms, the time histories of large translations and rotations with small three-dimensional warping have been integrated. Numerical simulations have been performed and the results have been compared to those of commercial software LS-DYNA. It can be concluded that the current modeling approach features high accuracy and that the new geometrically exact beam with warping is robust enough to predict large deformations with small strain.
Parallel beam dynamics calculations on high performance computers
International Nuclear Information System (INIS)
Faced with a backlog of nuclear waste and weapons plutonium, as well as an ever-increasing public concern about safety and environmental issues associated with conventional nuclear reactors, many countries are studying new, accelerator-driven technologies that hold the promise of providing safe and effective solutions to these problems. Proposed projects include accelerator transmutation of waste (ATW), accelerator-based conversion of plutonium (ABC), accelerator-driven energy production (ADEP), and accelerator production of tritium (APT). Also, next-generation spallation neutron sources based on similar technology will play a major role in materials science and biological science research. The design of accelerators for these projects will require a major advance in numerical modeling capability. For example, beam dynamics simulations with approximately 100 million particles will be needed to ensure that extremely stringent beam loss requirements (less than a nanoampere per meter) can be met. Compared with typical present-day modeling using 10,000-100,000 particles, this represents an increase of 3-4 orders of magnitude. High performance computing (HPC) platforms make it possible to perform such large scale simulations, which require 10's of GBytes of memory. They also make it possible to perform smaller simulations in a matter of hours that would require months to run on a single processor workstation. This paper will describe how HPC platforms can be used to perform the numerically intensive beam dynamics simulations required for development of these new accelerator-driven technologies
Studies of beam dynamics in relativistic klystron two-beam accelerators
Energy Technology Data Exchange (ETDEWEB)
Lidia, Steven M.
1999-11-01
Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band ({approximately}8-12 GHz) through Ka band ({approximately} 30-35 GHz) frequency regions. Provided that further prototyping shows stable beam propagation with minimal current loss and production of good quality, high-power rf fields, this technology is compatible with current schemes for electron-positron colliders in the multi-TeV center-of-mass scale. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split-operation algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 GW of power from 40 input, gain, and output rv cavities over a 10 m distance. The simulations show that beam current losses are acceptable, and that longitudinal and transverse focusing techniques are sufficient capable of maintaining a high degree of beam quality along the entire beamline. Additional
International Nuclear Information System (INIS)
These proceedings contain the papers presented at the 'Second advanced beam dynamics workshop on aperture-related limitations of the performance and beam lifetime in storage rings', which was organized in Lugano, Switzerland, from 11 to 16 April 1988, by the Beam Dynamics Panel of the International Committee for Future Accelerators (ICFA). The papers cover experiments on existing accelerators, analytical methods for determining amplitude limitations, criteria for the properties of the circulating beam and for the quality of accelerator components, and compensation schemes for field defects. (orig.)
Crossed molecular beam studies of unimolecular reaction dynamics
International Nuclear Information System (INIS)
The study of seven radical-molecule reactions using the crossed molecular beam technique with supersonic nozzle beams is reported. Product angular and velocity distributions were obtained and compared with statistical calculations in order to identify dynamical features of the reactions. In the reaction of chlorine and fluorine atoms with vinyl bromide, the product energy distributions are found to deviate from predictions of the statistical model. A similar effect is observed in the reaction of chlorine atoms with 1, 2 and 3-bromopropene. The reaction of oxygen atoms with ICl and CF3I has been used to obtain an improved value of the IO bond energy, 55.0 +- 2.0 kcal mol-1. In all reactions studied, the product energy and angular distributions are found to be coupled, and this is attributed to a kinematic effect of the conservation of angular momentum
Beam dynamics studies of the Heavy Ion Fusion Accelerator injector
International Nuclear Information System (INIS)
A driver-scale injector for the Heavy Ion Fusion Accelerator project has been built at LBL. This machine has exceeded the design goals of high voltage (> 2 MV), high current (> 0.8 A of K+) and low normalized emittance (< 1 π mm-mr). The injector consists of a 750 keV diode pre-injector followed by an electrostatic quadrupole accelerator (ESQ) which provides strong (alternating gradient) focusing for the space-charge dominated beam and simultaneously accelerates the ions to 2 MeV. The fully 3-D PIC code WARP together with EGUN and POISSON were used to design the machine and analyze measurements of voltage, current and phase space distributions. A comparison between beam dynamics characteristics as measured for the injector and corresponding computer calculations will be presented
Crossed-beam studies of the dynamics of radical reactions
Energy Technology Data Exchange (ETDEWEB)
Liu, K. [Argonne National Laboratory, IL (United States)
1993-12-01
The objective of this program is to characterize the detailed dynamics of elementary radical reactions and to provide a better understanding of radical reactivity in general. The radical beam is typically generated by a laser photolysis method. After colliding with the reacting molecule in a crossed-beam apparatus, the reaction product state distribution is interrogated by laser spectroscopic techniques. Several radicals of combustion significance, such as O, CH, OH, CN and NCO have been successfully generated and their collisional behavior at the state-to-state integral cross section level of detail has been studied in this manner. During the past year, the detection system has been converted from LIF to REMPI schemes, and the emphasis of this program shifted to investigate the product angular distributions. Both inelastic and reactive processes have been studied.
Nonlinear dynamic response of beam and its application in nanomechanical resonator
Institute of Scientific and Technical Information of China (English)
Yin Zhang; Yun Liu; Kevin D. Murphy
2012-01-01
Nonlinear dynamic response of nanomechanical resonator is of very important characteristics in its application.Two categories of the tension-dominant and curvaturedominant nonlinearities are analyzed.The dynamic nonlinearity of four beam structures of nanomechanical resonator is quantitatively studied via a dimensional analysis approach.The dimensional analysis shows that for the nanomechanical resonator of tension-dominant nonlinearity,its dynamic nonlinearity decreases monotonically with increasing axial loading and increases monotonically with the increasing aspect ratio of length to thickness; the dynamic nonlinearity can only result in the hardening effects.However,for the nanomechanical resonator of the curvature-dominant nonlinearity,its dynamic nonlinearity is only dependent on axial loading.Compared with the tension-dominant nonlinearity,the curvature-dominant nonlinearity increases monotonically with increasing axial loading; its dynamic nonlinearity can result in both hardening and softening effects.The analysis on the dynamic nonlinearity can be very helpful to the tuning application of the nanomechanical resonator.
Dynamic steering beams for efficient force measurement in optical manipulation
Institute of Scientific and Technical Information of China (English)
Xiaocong Yuan; Yuquan Zhang; Rui Cao; Xing Zhao; Jing Bu; Siwei Zhu
2011-01-01
@@ An efficient and inexpensive method that uses a glass plate mounted onto a motorized rotating stage as a beam-steering device for the generation of dynamic optical traps is reported.Force analysis reveals that there are drag and trapping forces imposed on the bead in the opposite directions, respectively, in a viscous medium.The trapped bead will be rotated following the beam's motion before it reaches the critical escape velocity when the drag force is equal to the optical trapping force.The equilibrium condition facilitates the experimental measurement of the drag force with potential extensions to the determination of the viscosity of the medium or the refractive index of the bead.The proposed technique can easily be integrated into conventional optical microscopic systems with minimum modifications.%An efficient and inexpensive method that uses a glass plate mounted onto a motorized rotating stage as a beam-steering device for the generation of dynamic optical traps is reported. Force analysis reveals that there are drag and trapping forces imposed on the bead in the opposite directions, respectively, in a viscous medium. The trapped bead will be rotated following the beam's motion before it reaches the critical escape velocity when the drag force is equal to the optical trapping force. The equilibrium condition facilitates the experimental measurement of the drag force with potential extensions to the determination of the viscosity of the medium or the refractive index of the bead. The proposed technique can easily be integrated into conventional optical microscopic systems with minimum modifications.
Some aspects of animal behavior and community dynamics
Directory of Open Access Journals (Sweden)
Vikas Rai
2011-09-01
Full Text Available We simulate the dynamical behavior of a few two - dimensional predator - prey systems in two - dimensional parameter spaces to gain insight into how functional responses affect community dynamics. The insight gained helps us design three dimensional systems. We construct models for a few ecosystems with three species and study them using computer simulations. The models have been developed by linking food chains which have both kinds of predators: specialist as well as generalist. The linking functions are weakly non-linear. The three dimensional model ecosystems have sexually reproducing top - predators. We perform extensive simulations to figure out dynamics of dynamical possibilities caused by changes in animal behavior. The animals change the foraging strategies and behave differently in different environments. At the end of the paper, we examine how diseases can govern transitions in meandering of dynamical models in bounded volume of their phase spaces.
Thermodynamic and gas dynamic aspects of a BLEVE
Mengmeng, X.
2007-01-01
This first chapter will give an introduction to what is a BLEVE, Boiling Liquid Expanding Vapor Explosion, and its hazards particularly in relation to tunnel safety. It will be shown that several definitions of a BLEVE can be given, depending on the aspect put in focus. In particular distinction can
Modeling of dynamic effects of a low power laser beam
Lawrence, George N.; Scholl, Marija S.; Khatib, AL
1988-01-01
Methods of modeling some of the dynamic effects involved in laser beam propagation through the atmosphere are addressed with emphasis on the development of simple but accurate models which are readily implemented in a physical optics code. A space relay system with a ground based laser facility is considered as an example. The modeling of such characteristic phenomena as laser output distribution, flat and curved mirrors, diffraction propagation, atmospheric effects (aberration and wind shear), adaptive mirrors, jitter, and time integration of power on target, is discussed.
Photon counting spectroscopic CT with dynamic beam attenuator
Atak, Haluk
2016-01-01
Purpose: Photon counting (PC) computed tomography (CT) can provide material selective CT imaging at lowest patient dose but it suffers from suboptimal count rate. A dynamic beam attenuator (DBA) can help with count rate by modulating x-ray beam intensity such that the low attenuating areas of the patient receive lower exposure, and detector behind these areas is not overexposed. However, DBA may harden the beam and cause artifacts and errors. This work investigates positive and negative effects of using DBA in PCCT. Methods: A simple PCCT with single energy bin, spectroscopic PCCT with 2 and 5 energy bins, and conventional energy integrating CT with and without DBA were simulated and investigated using 120kVp tube voltage and 14mGy air dose. The DBAs were modeled as made from soft tissue (ST) equivalent material, iron (Fe), and holmium (Ho) K-edge material. A cylindrical CT phantom and chest phantom with iodine and CaCO3 contrast elements were used. Image artifacts and quantification errors in general and mat...
Thermodynamic and gas dynamic aspects of a BLEVE
Mengmeng, X.
2007-01-01
This first chapter will give an introduction to what is a BLEVE, Boiling Liquid Expanding Vapor Explosion, and its hazards particularly in relation to tunnel safety. It will be shown that several definitions of a BLEVE can be given, depending on the aspect put in focus. In particular distinction can be made between two groups of references, respectively giving an engineering definition and a physical definition. As a result of our literature survey, our own definition of BLEVE will be present...
Chaotic dynamics of flexible Euler-Bernoulli beams
Energy Technology Data Exchange (ETDEWEB)
Awrejcewicz, J., E-mail: awrejcew@p.lodz.pl [Department of Automation, Biomechanics and Mechatronics, Lodz University of Technology, 1/15 Stefanowski St., 90-924 Lodz, Poland and Department of Vehicles, Warsaw University of Technology, 84 Narbutta St., 02-524 Warsaw (Poland); Krysko, A. V., E-mail: anton.krysko@gmail.com [Department of Applied Mathematics and Systems Analysis, Saratov State Technical University, Politehnicheskaya 77, 410054 Saratov (Russian Federation); Kutepov, I. E., E-mail: iekutepov@gmail.com; Zagniboroda, N. A., E-mail: tssrat@mail.ru; Dobriyan, V., E-mail: Dobriy88@yandex.ru; Krysko, V. A., E-mail: tak@san.ru [Department of Mathematics and Modeling, Saratov State Technical University, Politehnicheskaya 77, 410054 Saratov (Russian Federation)
2013-12-15
Mathematical modeling and analysis of spatio-temporal chaotic dynamics of flexible simple and curved Euler-Bernoulli beams are carried out. The Kármán-type geometric non-linearity is considered. Algorithms reducing partial differential equations which govern the dynamics of studied objects and associated boundary value problems are reduced to the Cauchy problem through both Finite Difference Method with the approximation of O(c{sup 2}) and Finite Element Method. The obtained Cauchy problem is solved via the fourth and sixth-order Runge-Kutta methods. Validity and reliability of the results are rigorously discussed. Analysis of the chaotic dynamics of flexible Euler-Bernoulli beams for a series of boundary conditions is carried out with the help of the qualitative theory of differential equations. We analyze time histories, phase and modal portraits, autocorrelation functions, the Poincaré and pseudo-Poincaré maps, signs of the first four Lyapunov exponents, as well as the compression factor of the phase volume of an attractor. A novel scenario of transition from periodicity to chaos is obtained, and a transition from chaos to hyper-chaos is illustrated. In particular, we study and explain the phenomenon of transition from symmetric to asymmetric vibrations. Vibration-type charts are given regarding two control parameters: amplitude q{sub 0} and frequency ω{sub p} of the uniformly distributed periodic excitation. Furthermore, we detected and illustrated how the so called temporal-space chaos is developed following the transition from regular to chaotic system dynamics.
Self-modulated dynamics of a relativistic charged particle beam in plasma wake field excitation
Akhter, T.; Fedele, R.; Nicola, S. De; Tanjia, F.; Jovanović, D.; Mannan, A.
2016-09-01
The self-modulated dynamics of a relativistic charged particle beam is provided within the context of the theory of plasma wake field excitation. The self-consistent description of the beam dynamics is provided by coupling the Vlasov equation with a Poisson-type equation relating the plasma wake potential to the beam density. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are discussed thereby.
Beam Dynamics Studies for a Laser Acceleration Experiment
Spencer, James; Noble, Robert; Palmer, Dennis T; Siemann, Robert
2005-01-01
The NLC Test Accelerator at SLAC was built to address various beam dynamics issues for the Next Linear Collider. An S-Band RF gun, originally proposed for the NLCTA, is being installed together with a large-angle extraction line at 60 MeV. This is followed by a matching section, final focus and buncher for the laser acceleration experiment, E163. The laser-electron interaction area is followed by a broad range, high resolution spectrometer (HES) for electron bunch analysis. The RF gun is discussed in another paper. We discuss only the beam dynamics and high resolution analysis system at 6 MeV based on using Parmela and high-order Transport for bunch charges from 50 pC to 1 nC. Beyond the diagnostics, this system uses the emittance compensating solenoids and a low energy, high resolution spectrometer (LES) to help tune for best operating point and match to the linac. Optical symmetries in the design of the 25.5° extraction line provide 1:1 phase space transfer without linear dispersion or use of sextu...
Parallel beam dynamics calculations on high performance computers
International Nuclear Information System (INIS)
Faced with a backlog of nuclear waste and weapons plutonium, as well as an ever-increasing public concern about safety and environmental issues associated with conventional nuclear reactors, many countries are studying new, accelerator-driven technologies that hold the promise of providing safe and effective solutions to these problems. Proposed projects include accelerator transmutation of waste (ATW), accelerator-based conversion of plutonium (ABC), accelerator-driven energy production (ADEP), and accelerator production of tritium (APT). Also, next-generation spallation neutron sources based on similar technology will play a major role in materials science and biological science research. The design of accelerators for these projects will require a major advance in numerical modeling capability. For example, beam dynamics simulations with approximately 100 million particles will be needed to ensure that extremely stringent beam loss requirements (less than a nanoampere per meter) can be met. Compared with typical present-day modeling using 10,000 endash 100,000 particles, this represents an increase of 3 endash 4 orders of magnitude. High performance computing (HPC) platforms make it possible to perform such large scale simulations, which require 10 close-quote s of GBytes of memory. They also make it possible to perform smaller simulations in a matter of hours that would require months to run on a single processor workstation. This paper will describe how HPC platforms can be used to perform the numerically intensive beam dynamics simulations required for development of these new accelerator-driven technologies. copyright 1997 American Institute of Physics
Study of Effect of Ion Source Energy Spread on RFQ Beam Dynamics at REX-ISOLDE
Fraser, M A
2013-01-01
With an upgrade to the Electron Beam Ion Source (EBIS) at REX under consideration a study was launched in order to understand the effect of an increased energy spread from the ion source on the beam dynamics of the RFQ. Due to the increased electron beam potential needed to achieve the upgrade’s charge breeding specification it is expected that the energy spread of the beam will increase from today’s estimated value of approximately +-0.1%. It is shown through beam dynamics simulations that the energy spread can be increased to +-1% without significant degradation of the beam quality output by the RFQ.
Beam dynamics simulations and measurements at the Project X Test Facility
Energy Technology Data Exchange (ETDEWEB)
Gianfelice-Wendt, E.; Scarpine, V.E.; Webber, R.C.; /Fermilab
2011-03-01
Project X, under study at Fermilab, is a multitask high-power superconducting RF proton beam facility, aiming to provide high intensity protons for rare processes experiments and nuclear physics at low energy, and simultaneously for the production of neutrinos, as well as muon beams in the long term. A beam test facility - former known as High Intensity Neutrino Source (HINS) - is under commissioning for testing critical components of the project, e.g. dynamics and diagnostics at low beam energies, broadband beam chopping, RF power generation and distribution. In this paper we describe the layout of the test facility and present beam dynamics simulations and measurements.
Electron-beam dynamics for an advanced flash-radiography accelerator
Energy Technology Data Exchange (ETDEWEB)
Ekdahl, Carl August Jr. [Los Alamos National Laboratory
2015-06-22
Beam dynamics issues were assessed for a new linear induction electron accelerator. Special attention was paid to equilibrium beam transport, possible emittance growth, and beam stability. Especially problematic would be high-frequency beam instabilities that could blur individual radiographic source spots, low-frequency beam motion that could cause pulse-to-pulse spot displacement, and emittance growth that could enlarge the source spots. Beam physics issues were examined through theoretical analysis and computer simulations, including particle-in cell (PIC) codes. Beam instabilities investigated included beam breakup (BBU), image displacement, diocotron, parametric envelope, ion hose, and the resistive wall instability. Beam corkscrew motion and emittance growth from beam mismatch were also studied. It was concluded that a beam with radiographic quality equivalent to the present accelerators at Los Alamos will result if the same engineering standards and construction details are upheld.
Thermal, mechanical and fluid flow aspects of the high power beam dump for FRIB
Avilov, Mikhail; Aaron, Adam; Amroussia, Aida; Bergez, Wladimir; Boehlert, Carl; Burgess, Thomas; Carroll, Adam; Colin, Catherine; Durantel, Florent; Ferrante, Paride; Fourmeau, Tiffany; Graves, Van; Grygiel, Clara; Kramer, Jacob; Mittig, Wolfgang; Monnet, Isabelle; Patel, Harsh; Pellemoine, Frederique; Ronningen, Reginald; Schein, Mike
2016-06-01
The Facility for Rare Isotope Beams (FRIB) under construction at Michigan State University is based on a 400 kW heavy ion accelerator and uses in-flight production and separation to generate rare isotope beams. The first section of the fragment separator houses the rare isotope production target, and the primary beam dump to stop the unreacted primary beam. The experimental program will use 400 kW ion beams from 16O to 238U. After interaction with the production target, over 300 kW in remaining beam power must be absorbed by the beam dump. A rotating water-cooled thin-shell metal drum was chosen as the basic concept for the beam dump. Extensive thermal, mechanical and fluid flow analyses were performed to evaluate the effects of the high power density in the beam dump shell and in the water. Many properties were optimized simultaneously, such as shell temperature, mechanical strength, fatigue strength, and radiation resistance. Results of the analyses of the beam dump performance with different design options will be discussed. For example, it was found that a design modification to the initial water flow pattern resulted in a substantial increase in the wall heat transfer coefficient. A detailed evaluation of materials for the shell is in progress. The widely used titanium alloy, Ti-6Al-4V (wt%), is presently considered as the best candidate, and is the subject of specific tests, such as studies of performance under heavy ion irradiation.
Thermodynamic aspects of information transfer in complex dynamical systems.
Cafaro, Carlo; Ali, Sean Alan; Giffin, Adom
2016-02-01
From the Horowitz-Esposito stochastic thermodynamical description of information flows in dynamical systems [J. M. Horowitz and M. Esposito, Phys. Rev. X 4, 031015 (2014)], it is known that while the second law of thermodynamics is satisfied by a joint system, the entropic balance for the subsystems is adjusted by a term related to the mutual information exchange rate between the two subsystems. In this article, we present a quantitative discussion of the conceptual link between the Horowitz-Esposito analysis and the Liang-Kleeman work on information transfer between dynamical system components [X. S. Liang and R. Kleeman, Phys. Rev. Lett. 95, 244101 (2005)]. In particular, the entropic balance arguments employed in the two approaches are compared. Notwithstanding all differences between the two formalisms, our work strengthens the Liang-Kleeman heuristic balance reasoning by showing its formal analogy with the recent Horowitz-Esposito thermodynamic balance arguments. PMID:26986295
Aspects of dynamical dimensional reduction in multigraph ensembles of CDT
Giasemidis, Georgios; Zohren, Stefan
2012-01-01
We study the continuum limit of a "radially reduced" approximation of Causal Dynamical Triangulations (CDT), so-called multigraph ensembles, and explain why they serve as realistic toy models to study the dimensional reduction observed in numerical simulations of four-dimensional CDT. We present properties of this approximation in two, three and four dimensions comparing them with the numerical simulations and pointing out some common features with 2+1 dimensional Horava-Lifshitz gravity.
Ion beam treatment of polymers application aspects from medicine to space
Kondyurin, Alexey; McKenzie, David
2010-01-01
Polymer materials are used in different fields of industries, from microelectronice to medicine. Ion beam implantation is method of surface modification when surface properties must be significantly changed and bulk properties of material must be saved. Ion Beam Treatment of Polymers contains results of polymer investigations and techniques development in the field of polymer modification by high energy ion beams. This book is intended for specialists in polymer science who have interest to use an ion beam treatment for improvement of polymer properties, for specialists in physics who search
Methodological aspects of EEG and Body dynamics measurements during motion.
Directory of Open Access Journals (Sweden)
Pedro eReis
2014-03-01
Full Text Available EEG involves recording, analysis, and interpretation of voltages recorded on the human scalp originating from brain grey matter. EEG is one of the favorite methods to study and understand processes that underlie behavior. This is so, because EEG is relatively cheap, easy to wear, light weight and has high temporal resolution. In terms of behavior, this encompasses actions, such as movements, that are performed in response to the environment. However, there are methodological difficulties when recording EEG during movement such as movement artifacts. Thus, most studies about the human brain have examined activations during static conditions. This article attempts to compile and describe relevant methodological solutions that emerged in order to measure body and brain dynamics during motion. These descriptions cover suggestions of how to avoid and reduce motion artifacts, hardware, software and techniques for synchronously recording EEG, EMG, kinematics, kinetics and eye movements during motion. Additionally, we present various recording systems, EEG electrodes, caps and methods for determination of real/custom electrode positions. In the end we will conclude that it is possible to record and analyze synchronized brain and body dynamics related to movement or exercise tasks.
Rodríguez Cordón, Marta; Ferrer Albiach, Carlos
2009-08-01
The main objective of image-guided radiation therapy (IGRT) equipment is to reduce and correct inherent errors in external radiotherapy processes. At the present time, there are different IGRT systems available, but here we will refer exclusively to the kilovoltage cone-beam CT onboard linear accelerator (CBkVCT) and the different aspects that, from a clinical point of view, should be taken into consideration before the implementation of this equipment.
Dynamic simulation and efficiency analysis of beam pumping system
Institute of Scientific and Technical Information of China (English)
邢明明; 董世民; 童志雄; 田然凤; 陈慧玲
2015-01-01
An improved whole model of beam pumping system was built. In the detail, for surface transmission system (STS), a new mathematical model was established considering the influence of some factors on the STS’s torsional vibration, such as the time variation characteristic of equivalent stiffness of belt and equivalent rotational inertia of crank. For the sucker rod string (SRS), an improved mathematical model was built considering the influence of some parameters on the SRS’s longitudinal vibration, such as the nonlinear friction of plunger, hydraulic loss of pump and clearance leakage. The dynamic response and system efficiency of whole system were analyzed. The results show that there is a jumping phenomenon in the amplitude frequency curve, and the system.
Dynamic Terahertz Beam Steering Based on Graphene Metasurfaces
Liu, Liming; Hattori, Haroldo T
2016-01-01
A full (2$\\pi$) phase modulation is critical for efficient wavefront manipulation. In this article, we propose a metasurface based on graphene long/short-strip resonators which are capable of implementing a dynamic 2$\\pi$ phase modulation by applying different voltages to different graphene resonators. The configuration is found to have high reflection efficiency (minimum 56%) and has a full phase modulation in a wide frequency range. Terahertz (THz) beam steering as large as 120 degrees ($\\pm60^\\circ$) is demonstrated in a broad frequency range (1.2 to 1.9 THz) by changing the Fermi levels of different graphene resonators accordingly. This metasurface can provide a new platform for effectively manipulating THz waves.
Energy Technology Data Exchange (ETDEWEB)
Gao, J
2000-12-01
Physically speaking, the delta function like beam-beam nonlinear forces at interaction points (IPs) act as a sum of delta function nonlinear multipoles. By applying the general theory established in ref. [1], in this paper we investigate analytically the beam-beam interaction limited dynamic apertures and the corresponding beam lifetimes for both the round and the flat beams. Relations between the beam-beam limited beam lifetimes and the beam-beam tune shifts are established, which show clearly why experimentally one has always a maximum beam-beam tune shift, {zeta}{sub y,max}, around 0.045 for e{sup +}e{sup -} circular colliders, and why one can use round beams to double this value approximately. Comparisons with some machine parameters are given. Finally, we discuss the mechanism of the luminosity reduction due to a definite collision crossing angle. (author)
Dynamic Aspects of Macrophage Polarizationduring Atherosclerosis Progression and Regression
Directory of Open Access Journals (Sweden)
Michael ePeled
2014-11-01
Full Text Available It is well recognized that macrophages in many contexts in vitro and in vivo display a spectrum of inflammatory features and functional properties. A convenient system to group together different subsets of macrophages has been the M1(inflammatory/M2(anti-inflammatory classification. In addition to other sites of inflammation, it is now established that atherosclerotic plaques contain both M1 and M2 macrophages. We review results made possible by a number of recent mouse models of atherosclerotic regression that, taken with other literature, have shown the M1/M2 balance in plaques to be dynamic, with M1 predominating in disease progression and M2 in regression. The regulation of the macrophage phenotype in plaques and the functional consequences of the M1 and M2 states in atherosclerosis will also be discussed.
An Aspect of Dynamic Human-structure Interaction
DEFF Research Database (Denmark)
Pedersen, Lars
2008-01-01
It is known that humans and structures interact. Humans can cause structures to vibrate, and excessive vibrations may occur if the motion frequency of humans coincides with a resonant frequency of the structural system. It is also known that stationary humans (such as humans sitting or standing...... on the structure) influence the dynamic behaviour and modal characteristics of the structure carrying them, whether being a grandstand, an office floor or similar. However, the interaction between the stationary humans and the structure is generally not well understood, and the paper addresses this interaction....... Focus is on how modal characteristics of the structure, i.e. its frequency and damping, are influenced by the presence of stationary humans. Vertical vibrations are considered, and particular focus is given the influence of human posture on modal characteristics of the supporting structure. Insight...
Testing Object-Oriented Programs using Dynamic Aspects and Non-Determinism
DEFF Research Database (Denmark)
Achenbach, Michael; Ostermann, Klaus
2010-01-01
decisions exposing private data. We present an approach that both improves the expressiveness of test cases using non-deterministic choice and reduces design modifications using dynamic aspect-oriented programming techniques. Non-deterministic choice facilitates local definitions of multiple executions...... without parameterization or generation of tests. It also eases modelling naturally non-deterministic program features like IO or multi-threading in integration tests. Dynamic AOP facilitates powerful design adaptations without exposing test features, keeping the scope of these adaptations local to each...... test. We also combine non-determinism and dynamic aspects in a new approach to testing multi-threaded programs using co-routines....
Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization.
Mentink-Vigier, Frederic; Akbey, Ümit; Oschkinat, Hartmut; Vega, Shimon; Feintuch, Akiva
2015-09-01
Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea-eb-n} during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This
Beam dynamics studies during commissioning of two undulators in Indus-2
International Nuclear Information System (INIS)
Indus-2, a synchrotron light source facility at RRCAT, Indore is in continuous operation at 2.5 GeV, generating the synchrotron radiation from its bending magnets. For enhancing the intensity of synchrotron radiation, two planar undulators have been installed and successfully commissioned with the Indus-2 electron beam. Various beam dynamical challenges such as beam accumulation, beam energy ramping and storage at 2.5 GeV have been addressed to ensure the smooth commissioning of these devices. Moreover, due to interaction of the stored beam with magnetic field of undulators, various parameters of the electron beam get changed. In this paper, the beam dynamics studies to ensure the smooth commissioning of these devices and its measured effect on beam parameters have been presented. (author)
Electron beam dynamics in the DARHT-II linear induction accelerator
Energy Technology Data Exchange (ETDEWEB)
Ekdahl, Carl A [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mccuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrata [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rowton, Lawrence [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Scarpetti, Raymond [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Trainham, C [NSTEC/STL; Williams, John [Los Alamos National Laboratory; Genoni, Thomas [VOSS; Hughes, Thomas [VOSS; Toma, Carsten [VOSS
2008-01-01
The DARHT-II linear induction accelerator (LIA) accelerates a 2-kA electron beam to more than 17 MeV. The beam pulse has a greater than 1.5-microsecond flattop region over which the electron kinetic energy is constant to within 1%. The beam dynamics are diagnosed with 21 beam-position monitors located throughout the injector, accelerator, and after the accelerator exit, where we also have beam imaging diagnostics. We discuss the tuning of the injector and accelerator, and present data for the resulting beam dynamics. We discuss the tuning procedures and other methods used to minimize beam motion, which is undesirable for its application as a bremsstrahlung source for multi-pulse radiography of exlosively driven hydrodynamic experiments. We also present beam stability measurements, which we relate to previous stability experiments at lower current and energy.
Clinical aspects and dynamics of auricular parasitosis in Gir cattle
Directory of Open Access Journals (Sweden)
Patrícia V.B. Leite
2013-03-01
Full Text Available We evaluated the dynamics of ear infestations caused by Rhabditis spp. and Raillietia spp., which were correlated with animal age, intensity of clinical signs and climate factors. Sixty-four Gir cattle were distributed into three groups: GA - 23 calves with 4 to 6 months of age; GB - 18 calves with 7 to 12 months of age; and GC - 23 heifers with 13 to 33 months of age. Five samplings, defined as S1, S2, S3, S4 and S5 were performed every three months from August 2008 to August 2009. The ear secretion was collected using the auricular washing method for the right ear and a swab for the left ear. A clinical assessment of the animals was performed, and they were classified according to the presence and severity of otitis. The highest relative frequency of rhabditosis was 52.2% in GC at the last sampling. In the first sampling, 42.2% of the animals were infested by Raillietia spp. The older cattle were more susceptible to infestations by both parasites. No correlation of Rhabditis spp. and Raillietia spp. parasitism with climate factors was found. The results showed that both parasites could infest Gir cattle, and in most cases, there was no co-infestation. Only older animals parasitized by the nematode showed clinical signs of the disease.
Dynamics of relativistic electron beam space charge compensation in a neutral gas
Energy Technology Data Exchange (ETDEWEB)
Kurilko, V.I.; Ognivenko, V.V.
1983-06-01
The dynamics of the space charge compensation of a relativistic electron beam with magnetized electrons as a result of ionization collisions of beam electrons and secondary ions with gas atoms has been studied theoretically. The analysis of calculation data shows that the neutral gas ionization by a relativistic electron beam leads to appearance of secondary ions which oscillate in a potential well of the electron beam space charge. It is shown that the density of ions formed is maximal in the beam center and drops to the beam periphery. As a result, the force compensation is possible only in the vicinity of a fixed coordinate which value grows with time.
Chaotic dynamics of flexible beams driven by external white noise
Awrejcewicz, J.; Krysko, A. V.; Papkova, I. V.; Zakharov, V. M.; Erofeev, N. P.; Krylova, E. Yu.; Mrozowski, J.; Krysko, V. A.
2016-10-01
Mathematical models of continuous structural members (beams, plates and shells) subjected to an external additive white noise are studied. The structural members are considered as systems with infinite number of degrees of freedom. We show that in mechanical structural systems external noise can not only lead to quantitative changes in the system dynamics (that is obvious), but also cause the qualitative, and sometimes surprising changes in the vibration regimes. Furthermore, we show that scenarios of the transition from regular to chaotic regimes quantified by Fast Fourier Transform (FFT) can lead to erroneous conclusions, and a support of the wavelet analysis is needed. We have detected and illustrated the modifications of classical three scenarios of transition from regular vibrations to deterministic chaos. The carried out numerical experiment shows that the white noise lowers the threshold for transition into spatio-temporal chaotic dynamics. A transition into chaos via the proposed modified scenarios developed in this work is sensitive to small noise and significantly reduces occurrence of periodic vibrations. Increase of noise intensity yields decrease of the duration of the laminar signal range, i.e., time between two successive turbulent bursts decreases. Scenario of transition into chaos of the studied mechanical structures essentially depends on the control parameters, and it can be different in different zones of the constructed charts (control parameter planes). Furthermore, we found an interesting phenomenon, when increase of the noise intensity yields surprisingly the vibrational characteristics with a lack of noisy effect (chaos is destroyed by noise and windows of periodicity appear).
Institute of Scientific and Technical Information of China (English)
XIAO Chen; HE Yuan; YUAN You-Jin; YAO Qing-Gao; WANG Zhi-Jun; CHANG Wei; LIU Yong; XIA Jia-Wen
2011-01-01
A new SSC-linac system (injector into separated sector cyclotron) is being designed in the HIRFL (heavy ion research facility of Lanzhou). As part of SSC-Linac, the LEBT (low energy beam transport) consists of seven solenoids, four quadrupoles, a bending magnet and an extra multi-harmonic buncher. The total length of this segment is about 7 meters. The beam dynamics in this LEBT has been studied using three-dimensional PIC (particle-in-cell) code BEAMPATH. The simulation results show that the continuous beam from the ion source is first well analyzed by a charge-to-mass selection system, and the beam of the selected charge-to-mass ratio is then efficiently pre-bunched by a multi-harmonic buncher and optimally matched into the RFQ (radio frequency quadrupole) for further acceleration. The principles and effects of the solenoid collimation channel are discussed, and it could limit the beam emittance by changing the aperture size.
Dynamic Light Scattering of Short Au Rods with Low Aspect Ratios
Rodriguez-Fernández, J.; Perez-Juste, J.; L.M. Liz-Marzán; Lang, P. R.
2007-01-01
The translational and rotational diffusion of a series of gold nanorods with low aspect ratios was investigated by dynamic light scattering (DLS). It is shown that the translational and rotational diffusion coefficients can be determined because the particle shape causes an anisotropy of the polarizability. This gives rise to two clearly distinguishable relaxation modes in the time correlation function of the scattered light. The particle length and aspect ratio were determined independently ...
Johansson, Nicklas
2011-01-01
This thesis studies different aspects of Flexible AC Transmission System (FACTS) devices which are used to improve the power transfer capability and increase the controllability in electric power systems. In the thesis, different aspects on the usage and control of Dynamic Power Flow Controllers (DPFC) and related FACTS devices are studied. The DPFC is a combination of a Phase Shifting Transformer (PST) and a Thyristor Switched Series Capacitor (TSSC)/Thyristor Switched Series Reactor (TSSR)....
Aspect-Aided Dynamic Non-Negative Sparse Representation-Based Microwave Image Classification
Zhang, Xinzheng; Yang, Qiuyue; Liu, Miaomiao; Jia, Yunjian; Liu, Shujun; Li, Guojun
2016-01-01
Classification of target microwave images is an important application in much areas such as security, surveillance, etc. With respect to the task of microwave image classification, a recognition algorithm based on aspect-aided dynamic non-negative least square (ADNNLS) sparse representation is proposed. Firstly, an aspect sector is determined, the center of which is the estimated aspect angle of the testing sample. The training samples in the aspect sector are divided into active atoms and inactive atoms by smooth self-representative learning. Secondly, for each testing sample, the corresponding active atoms are selected dynamically, thereby establishing dynamic dictionary. Thirdly, the testing sample is represented with ℓ1-regularized non-negative sparse representation under the corresponding dynamic dictionary. Finally, the class label of the testing sample is identified by use of the minimum reconstruction error. Verification of the proposed algorithm was conducted using the Moving and Stationary Target Acquisition and Recognition (MSTAR) database which was acquired by synthetic aperture radar. Experiment results validated that the proposed approach was able to capture the local aspect characteristics of microwave images effectively, thereby improving the classification performance. PMID:27598172
Aspect-Aided Dynamic Non-Negative Sparse Representation-Based Microwave Image Classification
Directory of Open Access Journals (Sweden)
Xinzheng Zhang
2016-09-01
Full Text Available Classification of target microwave images is an important application in much areas such as security, surveillance, etc. With respect to the task of microwave image classification, a recognition algorithm based on aspect-aided dynamic non-negative least square (ADNNLS sparse representation is proposed. Firstly, an aspect sector is determined, the center of which is the estimated aspect angle of the testing sample. The training samples in the aspect sector are divided into active atoms and inactive atoms by smooth self-representative learning. Secondly, for each testing sample, the corresponding active atoms are selected dynamically, thereby establishing dynamic dictionary. Thirdly, the testing sample is represented with ℓ 1 -regularized non-negative sparse representation under the corresponding dynamic dictionary. Finally, the class label of the testing sample is identified by use of the minimum reconstruction error. Verification of the proposed algorithm was conducted using the Moving and Stationary Target Acquisition and Recognition (MSTAR database which was acquired by synthetic aperture radar. Experiment results validated that the proposed approach was able to capture the local aspect characteristics of microwave images effectively, thereby improving the classification performance.
Aspect-Aided Dynamic Non-Negative Sparse Representation-Based Microwave Image Classification.
Zhang, Xinzheng; Yang, Qiuyue; Liu, Miaomiao; Jia, Yunjian; Liu, Shujun; Li, Guojun
2016-01-01
Classification of target microwave images is an important application in much areas such as security, surveillance, etc. With respect to the task of microwave image classification, a recognition algorithm based on aspect-aided dynamic non-negative least square (ADNNLS) sparse representation is proposed. Firstly, an aspect sector is determined, the center of which is the estimated aspect angle of the testing sample. The training samples in the aspect sector are divided into active atoms and inactive atoms by smooth self-representative learning. Secondly, for each testing sample, the corresponding active atoms are selected dynamically, thereby establishing dynamic dictionary. Thirdly, the testing sample is represented with ℓ 1 -regularized non-negative sparse representation under the corresponding dynamic dictionary. Finally, the class label of the testing sample is identified by use of the minimum reconstruction error. Verification of the proposed algorithm was conducted using the Moving and Stationary Target Acquisition and Recognition (MSTAR) database which was acquired by synthetic aperture radar. Experiment results validated that the proposed approach was able to capture the local aspect characteristics of microwave images effectively, thereby improving the classification performance. PMID:27598172
Beam dynamics design and electromagnetic analysis of 3 MeV RFQ for TAC Proton Linac
Institute of Scientific and Technical Information of China (English)
A Caliskan; HF Kisoglu; M Yilmaz
2015-01-01
A beam dynamics design of 352.2 MHz radio-frequency quadrupole (RFQ) of Turkish Accelerator Cen-ter (TAC) project which accelerates continuous wave (CW) proton beam with 30 mA current from 50 keV to 3 MeV kinetic energy has been performed in this study. Also, it includes error analysis of the RFQ, in which some fluctuations have been introduced to input beam parameters to see how the output beam parameters are affected, two-dimensional (2-D) and three-dimensional (3-D) electromagnetic structural design of the RFQ to obtain optimum cavity paramaters that agree with the ones of the beam dynamics. The beam dynamics and error analysis of the RFQ have been done by using LIDOS.RFQ. Electromagnetic design parameters have been obtained by using SUPERFISH for 2-D cavity geometry and CST Microwave Studio for 3-D cavity geometry.
Dosimetric aspects of the therapeutic photon beams from a dual-energy linear accelerator
Energy Technology Data Exchange (ETDEWEB)
Al-Ghazi, M.S.A.L.; Arjune, B.; Fiedler, J.A.; Sharma, P.D.
1988-03-01
Parameters of the photon beams (6 and 20 MV) from a dual-energy linear accelerator (Mevatron-KD, Siemens Medical Laboratories, CA) are presented. The depth dose characteristics of the photon beams are d/sub max/ of 1.8 and 3.8 cm and percentage depth dose of 68% and 80% at 10-cm depth and 100-cm source--surface distance for a field size of 10 x 10 cm/sup 2/ for 6 and 20 MV, respectively. The 6 and 20 MV beams were found to correspond to nominal accelerating potentials of 4.7 and 17 MV, respectively. The stability of output is within +- 1% and flatness and symmetry are within +- 3%. These figures compare favorably with the manufacturer's specifications.
Dynamic Calculation Method of Beam System Under Low Velocity Impact
Institute of Scientific and Technical Information of China (English)
LI Wen-pei; WANG De-rong; SONG Chun-ming; WANG Ming-yang
2008-01-01
The beating beams and the supporting beams under low velocity impact may be in four different strain stages of deformation depending on the impact intensity and beam structure strength. Based on the different judging conditions of deformation stages, the corresponding calculation models are proposed, the calculation formulae for the determination of the impact force and the beam's lateral displacement are obtained. Calculation shows that the beam's total deflection is small when the flexibility of the supporting component is high and the effect of diminishing deflection disappears almost when the stiffness of the supporting component is high.
De Martino, Salvatore; De Siena, Silvio; Illuminati, Fabrizio
1998-01-01
A recent proposal (see quant-ph/9803068) to simulate semiclassical corrections to classical dynamics by suitable classical stochastic fluctuations is applied to the specific instance of charged beam dynamics in particle accelerators. The resulting picture is that the collective beam dynamics, at the leading semiclassical order in Planck constant can be described by a particular diffusion process, the Nelson process, which is time-reversal invariant. Its diffusion coefficient $\\sqrt{N}\\lambda_...
Aspects of Metal Surface Glowing Mechanisms with Intensive Electron Beam Bombardment
Directory of Open Access Journals (Sweden)
I.V. Barsuk
2012-06-01
Full Text Available The paper gives a brief description and analysis of the main physical processes which can have an effect on the glowing nature of metal element surfaces in different electric vacuum devices when they are bombarded by electron beams. It has been found that the electron glowing effects on metal surfaces according to the electron energy can be explained with the help of the transition scattering on plasma waves or just with the classical transition radiation effect. This fact is rather important in terms of classical physics interpretation of the observed glowing effects on metal surface elements and techniques optimization of metal and electron beams diagnostics as well.
Directory of Open Access Journals (Sweden)
Theo van der Weide
2016-07-01
Full Text Available Modeling is one of the most important parts of requirements engineering. Most modeling techniques focus primarily on their pragmatics and pay less attention to their syntax and semantics. Different modeling techniques describe different aspects, for example, Object-Role Modeling (ORM describes underlying concepts and their relations while System Dynamics (SD focuses on the dynamic behavior of relevant objects in the underlying application domain. In this paper we provide an inductive definition for a generic modeling technique. Not only do we describe the underlying data structure, we also show how states can be introduced for relevant concepts and how their life cycles can be modeled in terms of System Dynamics. We also show how decomposition can be applied to master complex application domains. As a result we get an integrated modeling technique covering both static and dynamic aspects of application domains. The inductive definition of this integrated modeling technique will facilitate the implementation of supporting tools for practitioners.
Beam Dynamics Studies for a Laser Acceleration Experiment
International Nuclear Information System (INIS)
The NLC Test Accelerator (NLCTA) at SLAC was built to address various beam dynamics issues for the Next Linear Collider. An S-Band RF gun is being installed together with a large-angle extraction line at 60 MeV followed by a matching section, buncher and final focus for the laser acceleration experiment, E163. The laser-electron interaction area is followed by a broad range, high resolution spectrometer (HES) for electron bunch analysis. Another spectrometer at 6 MeV will be used for analysis of bunch charges up to 1 nC. Emittance compensating solenoids and the low energy spectrometer (LES) will be used to tune for best operating point and match to the linac. Optical symmetries in the design of the 25.5o extraction line provide 1:1 phase space transfer without use of sextupoles for a large, 6D phase space volume and range of input conditions. Design techniques, tolerances, tuning sensitivities and orthogonal knobs are discussed
Dynamic Euler-Bernoulli Beam Equation: Classification and Reductions
Directory of Open Access Journals (Sweden)
R. Naz
2015-01-01
Full Text Available We study a dynamic fourth-order Euler-Bernoulli partial differential equation having a constant elastic modulus and area moment of inertia, a variable lineal mass density g(x, and the applied load denoted by f(u, a function of transverse displacement u(t,x. The complete Lie group classification is obtained for different forms of the variable lineal mass density g(x and applied load f(u. The equivalence transformations are constructed to simplify the determining equations for the symmetries. The principal algebra is one-dimensional and it extends to two- and three-dimensional algebras for an arbitrary applied load, general power-law, exponential, and log type of applied loads for different forms of g(x. For the linear applied load case, we obtain an infinite-dimensional Lie algebra. We recover the Lie symmetry classification results discussed in the literature when g(x is constant with variable applied load f(u. For the general power-law and exponential case the group invariant solutions are derived. The similarity transformations reduce the fourth-order partial differential equation to a fourth-order ordinary differential equation. For the power-law applied load case a compatible initial-boundary value problem for the clamped and free end beam cases is formulated. We deduce the fourth-order ordinary differential equation with appropriate initial and boundary conditions.
Institute of Scientific and Technical Information of China (English)
朱正佑; 李根国; 程昌钧
2002-01-01
The equations of motion governing the quasi-static and dynamical behavior of a viscoelastic Timoshenko beam are derived. The viscoelastic material is assumed to obey a three-dimensional fractional derivative constitutive relation. The quasi-static behavior of the viscoelastic Timoshenko beam under step loading is analyzed and the analytical solution is obtained. The influence of material parameters on the deflection is investigated. The dynamical response of the viscoelastic Timoshenko beam subjected to a periodic excitation is studied by means of mode shape functions. And the effect of both transverse shear and rotational inertia on the vibration of the beam is discussed.
Fu, Yiming; Chen, Yang; Zhong, Jun
2014-10-01
The nonlinear dynamic response problems of fiber-metal laminated beams with delamination are studied in this paper. Basing on the Timoshenko beam theory, and considering geometric nonlinearity, transverse shear deformation, temperature effect and contact effect, the nonlinear governing equations of motion for fiber-metal laminated beams under unsteady temperature field are established, which are solved by the differential quadrature method, Nermark-β method and iterative method. In numerical examples, the effects of delamination length, delamination depth, temperature field, geometric nonlinearity and transverse shear deformation on the nonlinear dynamic response of the glass reinforced aluminum laminated beam with delamination are discussed in details.
Transverse beam dynamics in non-linear Fixed Field Alternating Gradient accelerators
Energy Technology Data Exchange (ETDEWEB)
Haj, Tahar M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2016-03-02
In this paper, we present some aspects of the transverse beam dynamics in Fixed Field Ring Accelerators (FFRA): we start from the basic principles in order to derive the linearized transverse particle equations of motion for FFRA, essentially FFAGs and cyclotrons are considered here. This is a simple extension of a previous work valid for linear lattices that we generalized by including the bending terms to ensure its correctness for FFAG lattice. The space charge term (contribution of the internal coulombian forces of the beam) is contained as well, although it is not discussed here. The emphasis is on the scaling FFAG type: a collaboration work is undertaken in view of better understanding the properties of the 150 MeV scaling FFAG at KURRI in Japan, and progress towards high intensity operation. Some results of the benchmarking work between different codes are presented. Analysis of certain type of field imperfections revealed some interesting features about this machine that explain some of the experimental results and generalize the concept of a scaling FFAG to a non-scaling one for which the tune variations obey a well-defined law.
International Nuclear Information System (INIS)
By the use of a neutron time of flight system at the Tandem Accelerator of the National Nuclear Research Institute; with neutrons provided by means of the 2 H(d, n) 3 He we intend to use the associated particle technique in order to have monoenergetic neutrons. This neutron beam will be used both in basic and applied research. (Author)
Varela-G, A
2003-01-01
By the use of a neutron time of flight system at the Tandem Accelerator of the National Nuclear Research Institute; with neutrons provided by means of the sup 2 H(d, n) sup 3 He we intend to use the associated particle technique in order to have monoenergetic neutrons. This neutron beam will be used both in basic and applied research. (Author)
Thermal and metallurgical aspects of electron beam welding of thick steel plates
International Nuclear Information System (INIS)
The electron-beam welding of thick carbon-manganese steel plates has been assessed. The thermal cycles in the heat affected zone (H.A.Z.) have been related to welding parameters. The weld metal composition hardness and toughness were evaluated with respect to the H.A.Z. properties
Directory of Open Access Journals (Sweden)
Z.L. Wang, Q. Wang, H.J. Li, J.J. Li, P. Xu, Q. Luo, A.Z. Jin, H.F. Yang and C.Z. Gu
2005-01-01
Full Text Available High aspect ratio diamond nanocone arrays are formed on freestanding diamond film by means of focused ion beam (FIB milling technology and hot-filament chemical vapor deposition (HFCVD method. The structure and phase purity of an individual diamond nanocone are characterized by scanning electron microscopy (SEM and micro-Raman spectroscopy. The result indicates that the diamond cones with high aspect ratio and small tip apex radius can be obtained by optimizing the parameters of FIB milling and diamond growth. The diamond nanocone arrays were also used to study the electron field emission properties and electric field shielding effect, finding high emission current density, low threshold and weak shielding effect, all attributable to the high field enhancement factor and suitable cone density of the diamond nanocone emitter
Dynamic Analysis of Kineto-Elastic Beam System with Second-order Effect
Institute of Scientific and Technical Information of China (English)
LU Nian-li; LUO Bing; XIA Yong-jun
2009-01-01
Dynamic equations of motional flexible beam elements were derived considering second-order effect. Non-linear finite element method and three-node Euler-Bernoulli beam elements were used. Because accuracy is higher in non-linear structural analysis, three-node beam elements are used to deduce shape functions and stiffness matrices in dynamic equations of flexible elements. Static condensation method was used to obtain the finial dynamic equations of three-node beam elements. According to geometrical relations of nodal displacements in concomitant and global coordinate system, dynamic equations of elements can be transformed to global coordinate system by concomitant coordinate method in order to build the global dynamic equations. Analyzed amplitude condition of flexible arm support of a port crane, the results show that second-order effect should be considered in kinetic-elastic analysis for heavy load machinery of big flexibility.
De Martino, S; Illuminati, F; Martino, Salvatore De; Siena, Silvio De; Illuminati, Fabrizio
1999-01-01
A recent proposal (see quant-ph/9803068) to simulate semiclassical corrections to classical dynamics by suitable classical stochastic fluctuations is applied to the specific instance of charged beam dynamics in particle accelerators. The resulting picture is that the collective beam dynamics, at the leading semiclassical order in Planck constant can be described by a particular diffusion process, the Nelson process, which is time-reversal invariant. Its diffusion coefficient $\\sqrt{N}\\lambda_{c}$ represents a semiclassical unit of emittance (here $N$ is the number of particles in the beam, and $\\lambda_{c}$ is the Compton wavelength). The stochastic dynamics of the Nelson type can be easily recast in the form of a Schroedinger equation, with the semiclassical unit of emittance replacing Planck constant. Therefore we provide a physical foundation to the several quantum-like models of beam dynamics proposed in recent years. We also briefly touch upon applications of the Nelson and Schroedinger formalisms to inc...
Stochastic collective dynamics of charged-particle beams in the stability regime.
Petroni, N C; De Martino, S; De Siena, S; Illuminati, F
2001-01-01
We introduce a description of the collective transverse dynamics of charged (proton) beams in the stability regime by suitable classical stochastic fluctuations. In this scheme, the collective beam dynamics is described by time-reversal invariant diffusion processes deduced by stochastic variational principles (Nelson processes). By general arguments, we show that the diffusion coefficient, expressed in units of length, is given by lambda(c)sqrt[N], where N is the number of particles in the beam and lambda(c) the Compton wavelength of a single constituent. This diffusion coefficient represents an effective unit of beam emittance. The hydrodynamic equations of the stochastic dynamics can be easily recast in the form of a Schrödinger equation, with the unit of emittance replacing the Planck action constant. This fact provides a natural connection to the so-called "quantum-like approaches" to beam dynamics. The transition probabilities associated to Nelson processes can be exploited to model evolutions suitable to control the transverse beam dynamics. In particular we show how to control, in the quadrupole approximation to the beam-field interaction, both the focusing and the transverse oscillations of the beam, either together or independently. PMID:11304370
Beintema, J.A.; Bijl, P.; Hogervorst, M.A.; Dijk, J.
2008-01-01
In an extensive Target Acquisition (TA) performance study, we recorded static and dynamic imagery of a set of military and civilian two-handheld objects at a range of distances and aspect angles with an under-sampled uncooled thermal imager. Next, we applied signal processing techniques including DS
Energy Technology Data Exchange (ETDEWEB)
Gorelick, Sergey; Guzenko, Vitaliy A; Vila-Comamala, Joan; David, Christian, E-mail: sergey.gorelick@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)
2010-07-23
Due to the ability of 100 keV electrons to penetrate deep into resist with little scattering, we were able to directly write various dense and high aspect ratio nanostructures in 540 nm and 1.1 {mu}m thick layers of poly(methyl methacrylate) (PMMA) resist. The PMMA molds produced by electron beam lithography were developed using a high contrast developer. The molds were used to transfer the pattern into metallic nanostructures by filling the developed trenches with Au by electroplating. By exposing lines narrower than the target width, we observed improved process latitude and line width control. The obtained aspect ratios of the dense structures are nearly 20 in 1.1 {mu}m PMMA layers and > 16 for structures electroplated into this PMMA mold. The fabrication method was successfully applied to produce Au diffractive x-ray Fresnel zone plates of exceptionally good quality with 50 and 70 nm outermost zones using 540 nm and 1.1 {mu}m thick PMMA molds. In addition, we also produced regular arrays of high aspect ratio and dense Au nanorods with periods down to 100 nm and high aspect ratio split-ring resonators.
Gorelick, Sergey; Guzenko, Vitaliy A.; Vila-Comamala, Joan; David, Christian
2010-07-01
Due to the ability of 100 keV electrons to penetrate deep into resist with little scattering, we were able to directly write various dense and high aspect ratio nanostructures in 540 nm and 1.1 µm thick layers of poly(methyl methacrylate) (PMMA) resist. The PMMA molds produced by electron beam lithography were developed using a high contrast developer. The molds were used to transfer the pattern into metallic nanostructures by filling the developed trenches with Au by electroplating. By exposing lines narrower than the target width, we observed improved process latitude and line width control. The obtained aspect ratios of the dense structures are nearly 20 in 1.1 µm PMMA layers and > 16 for structures electroplated into this PMMA mold. The fabrication method was successfully applied to produce Au diffractive x-ray Fresnel zone plates of exceptionally good quality with 50 and 70 nm outermost zones using 540 nm and 1.1 µm thick PMMA molds. In addition, we also produced regular arrays of high aspect ratio and dense Au nanorods with periods down to 100 nm and high aspect ratio split-ring resonators.
Sonar beam dynamics in leaf-nosed bats.
Linnenschmidt, Meike; Wiegrebe, Lutz
2016-01-01
Ultrasonic emissions of bats are directional and delimit the echo-acoustic space. Directionality is quantified by the aperture of the sonar beam. Recent work has shown that bats often widen their sonar beam when approaching movable prey or sharpen their sonar beam when navigating through cluttered habitats. Here we report how nose-emitting bats, Phyllostomus discolor, adjust their sonar beam to object distance. First, we show that the height and width of the bats sonar beam, as imprinted on a parabolic 45 channel microphone array, varies even within each animal and this variation is unrelated to changes in call level or spectral content. Second, we show that these animals are able to systematically decrease height and width of their sonar beam while focusing on the approaching object. Thus it appears that sonar beam sharpening is a further, facultative means of reducing search volume, likely to be employed by stationary animals when the object position is close and unambiguous. As only half of our individuals sharpened their beam onto the approaching object we suggest that this strategy is facultative, under voluntary control, and that beam formation is likely mediated by muscular control of the acoustic aperture of the bats' nose leaf.
Quasi-static and dynamical bending of a cantilever poroelastic beam
Institute of Scientific and Technical Information of China (English)
YANG Yi; LI Li; YANG Xiao
2009-01-01
Based on the theory of porous media, the quasi-static and dynamical bending of a cantilever poroelastic beam subjected to a step load at its free end is investigated, and the influences of its permeability on bending deformation is examined.The initial boundary value problems for dynamical and quasi-static responses are solved with the Laplace transform technique,and the deflections, the bending moments of the solid skeleton and the equivalent couples of the pore fluid pressure are shown in figures. It is shown that the dynamical and quasi-static behavior of the saturated poroelastic beam depends closely on the permeability conditions at the beam ends. Under the different permeability conditions, the deflections of the beam may oscillate or not. The Mandel-Cryer effect also exists in liquid-saturated poroelastic beams.
Investigation of the transverse beam dynamics in the thermal wave model with a functional method
Jang, Ji-Ho; Cho, Yong-sub; Kwon, Hyeok-jung
2006-01-01
We investigated the transverse beam dynamics in a thermal wave model by using a functional method. It can describe the beam optical elements separately with a kernel for a component. The method can be applied to general quadrupole magnets beyond a thin lens approximation as well as drift spaces. We found that the model can successfully describe the PARMILA simulation result through an FODO lattice structure for the Gaussian input beam without space charge effects.
End to End Beam Dynamics of the ESS Linac
DEFF Research Database (Denmark)
Thomsen, Heine Dølrath
2012-01-01
The European Spallation Source, ESS, uses a linear accelerator to deliver a high intensity proton beam to the target station. The nominal beam power on target will be 5 MW at an energy of 2.5 GeV. We briefly describe the individual accelerating structures and transport lines through which we have...
Experimental validation of flexible multibody dynamics beam formulations
Energy Technology Data Exchange (ETDEWEB)
Bauchau, Olivier A., E-mail: olivier.bauchau@sjtu.edu.cn; Han, Shilei [University of Michigan-Shanghai Jiao Tong University Joint Institute (China); Mikkola, Aki; Matikainen, Marko K. [Lappeenranta University of Technology, Department of Mechanical Engineering (Finland); Gruber, Peter [Austrian Center of Competence in Mechatronics GmbH (Austria)
2015-08-15
In this paper, the accuracies of the geometrically exact beam and absolute nodal coordinate formulations are studied by comparing their predictions against an experimental data set referred to as the “Princeton beam experiment.” The experiment deals with a cantilevered beam experiencing coupled flap, lag, and twist deformations. In the absolute nodal coordinate formulation, two different beam elements are used. The first is based on a shear deformable approach in which the element kinematics is described using two nodes. The second is based on a recently proposed approach featuring three nodes. The numerical results for the geometrically exact beam formulation and the recently proposed three-node absolute nodal coordinate formulation agree well with the experimental data. The two-node beam element predictions are similar to those of linear beam theory. This study suggests that a careful and thorough evaluation of beam elements must be carried out to assess their ability to deal with the three-dimensional deformations typically found in flexible multibody systems.
Beam dynamics studies to develop LHC luminosity model
Campogiani, Giovanna; Papaphilippou, Ioannis
The thesis project aims at studying the different physical processes that are impacting luminosity, one of the key figures of merit of a collider operation. In particular the project focuses on extracting the most relevant parameters for the high-energy part of the model, which is mostly dominated by the beam-beam effect. LHC luminosity is degraded by parasitic collisions that reduce the beam lifetime and the particles stability in the collider. This instability is due to the non-linear effects of one beam electromagnetic field on another in the interaction region. Such parasitic encounters can be as many as 16 per interaction region, piling up to around 180 000 per second. Our goal is to study the evolution of charge density distribution in the beam, by tracking particles through a symplectic integrator that includes the beam-beam effect. In particular we want to obtain data on the halo particles, which are more sensible to instability, to better characterise the beam lifetime and monitor the luminosity evol...
Radiative damping and electron beam dynamics in plasma-based accelerators.
Michel, P; Schroeder, C B; Shadwick, B A; Esarey, E; Leemans, W P
2006-08-01
The effects of radiation reaction on electron beam dynamics are studied in the context of plasma-based accelerators. Electrons accelerated in a plasma channel undergo transverse betatron oscillations due to strong focusing forces. These oscillations lead to emission by the electrons of synchrotron radiation, with a corresponding energy loss that affects the beam properties. An analytical model for the single particle orbits and beam moments including the classical radiation reaction force is derived and compared to the results of a particle transport code. Since the betatron amplitude depends on the initial transverse position of the electron, the resulting radiation can increase the relative energy spread of the beam to significant levels (e.g., several percent). This effect can be diminished by matching the beam into the channel, which could require micron sized beam radii for typical values of the beam emittance and plasma density.
Radiative damping and electron beam dynamics in plasma-based accelerators
Michel, P.; Schroeder, C. B.; Shadwick, B. A.; Esarey, E.; Leemans, W. P.
2006-08-01
The effects of radiation reaction on electron beam dynamics are studied in the context of plasma-based accelerators. Electrons accelerated in a plasma channel undergo transverse betatron oscillations due to strong focusing forces. These oscillations lead to emission by the electrons of synchrotron radiation, with a corresponding energy loss that affects the beam properties. An analytical model for the single particle orbits and beam moments including the classical radiation reaction force is derived and compared to the results of a particle transport code. Since the betatron amplitude depends on the initial transverse position of the electron, the resulting radiation can increase the relative energy spread of the beam to significant levels (e.g., several percent). This effect can be diminished by matching the beam into the channel, which could require micron sized beam radii for typical values of the beam emittance and plasma density.
Beam Dynamics Observations of the 2015 High Intensity Scrubbing Runs at the Cern Sps
Bartosik, Hannes; Li, Kevin; Mether, Lotta; Romano, Annalisa; Rumolo, Giovanni; Schenk, Michael
2016-01-01
Beam quality degradation caused by e-cloud effects has been identified as one of the main performance limitations for high intensity LHC beams with 25 ns bunch spacing in the SPS. In view of the beam parameters targeted with the LHC injectors upgrade (LIU) project, about two weeks of SPS machine time in 2015 were devoted to dedicated scrubbing runs with high intensity LHC 25 ns and dedicated 'doublet' beams in order to study the achievable reduction of e-cloud effects and quantify the consequent beam performance improvements. This paper describes the main observations concerning the coherent instabilities and beam dynamics limitations encountered as well as a detailed characterisation of the performance reach with the highest beam intensity presently available from the pre-injectors.
Dynamic spatial structure of spontaneous beams in photorefractive bismuth sillicon oxide
DEFF Research Database (Denmark)
Buchhave, Preben; Lyuksyutov, S.; Vasnetsov, M.;
1996-01-01
We report the domain structure of spontaneously occurring beams (subharmonics) in photorefractive bismuth silicon oxide with an applied electric field from 1 to 6 kV/cm and a running grating. The subharmonic beams are generated in a pattern of domains that evolve dynamically as they move through ...
Dynamic stiffness matrix development and free vibration analysis of a moving beam
Banerjee, J. R.; Gunawardana, W. D.
2007-06-01
The dynamic stiffness matrix of a moving Bernoulli-Euler beam is developed and used to investigate its free flexural vibration characteristics. In order to develop the dynamic stiffness matrix, it is necessary to derive and solve the governing differential equation of motion of the moving beam in closed analytical form. The solution is then used to obtain the general expressions for both responses and loads. Boundary conditions are applied to determine the constants in the general solution, leading to the formation of the frequency dependent dynamic stiffness matrix of the moving beam, relating the amplitudes of the harmonically varying loads to those of the corresponding responses. The application of the resulting dynamic stiffness matrix using the Wittrick-Williams algorithm is demonstrated by some illustrative examples. Numerical results for both simply supported and fixed-fixed end conditions of the beam are discussed, and wherever possible, some are compared with those available in the literature.
Dynamic cone beam CT angiography of carotid and cerebral arteries using canine model
International Nuclear Information System (INIS)
Purpose: This research is designed to develop and evaluate a flat-panel detector-based dynamic cone beam CT system for dynamic angiography imaging, which is able to provide both dynamic functional information and dynamic anatomic information from one multirevolution cone beam CT scan. Methods: A dynamic cone beam CT scan acquired projections over four revolutions within a time window of 40 s after contrast agent injection through a femoral vein to cover the entire wash-in and wash-out phases. A dynamic cone beam CT reconstruction algorithm was utilized and a novel recovery method was developed to correct the time-enhancement curve of contrast flow. From the same data set, both projection-based subtraction and reconstruction-based subtraction approaches were utilized and compared to remove the background tissues and visualize the 3D vascular structure to provide the dynamic anatomic information. Results: Through computer simulations, the new recovery algorithm for dynamic time-enhancement curves was optimized and showed excellent accuracy to recover the actual contrast flow. Canine model experiments also indicated that the recovered time-enhancement curves from dynamic cone beam CT imaging agreed well with that of an IV-digital subtraction angiography (DSA) study. The dynamic vascular structures reconstructed using both projection-based subtraction and reconstruction-based subtraction were almost identical as the differences between them were comparable to the background noise level. At the enhancement peak, all the major carotid and cerebral arteries and the Circle of Willis could be clearly observed. Conclusions: The proposed dynamic cone beam CT approach can accurately recover the actual contrast flow, and dynamic anatomic imaging can be obtained with high isotropic 3D resolution. This approach is promising for diagnosis and treatment planning of vascular diseases and strokes.
Beam dynamics studies in the driver LINAC pre-stripper section of the RIA facility
Indian Academy of Sciences (India)
E S Lessner; P N Ostroumov
2002-12-01
The RIA facility driver LINAC consists of about 400 superconducting (SC) independently phased rf cavities. The LINAC is designed to accelerate simultaneously several charge-state beams to generate as much as 400 kW of uranium beam power. The LINAC beam dynamics is most sensitive to the focusing and accelerating structure parameters of the pre-stripper section, where the uranium beam is accelerated from 0.17 keV/u to 9.4 MeV/u. This section is designed to accept and accelerate two charge states (28 and 29) of uranium beam from an ECR ion source. The pre-stripper section must be designed to minimize the beam emittance distortion of this two-charge-state beam. In particular, the inter-cryostat spaces must be minimized and beam parameters near transitions of the accelerating and focusing lattices must be matched carefully. Several sources of possible effective emittance growth are considered in the design of the pre-stripper section and a tolerance budget is established. Numerical beam dynamics studies include realistic electric and magnetic three-dimensional ﬁeld distributions in the SC rf cavities and SC solenoids. Error effects in the longitudinal beam parameters are studied.
Beam dynamics requirement for proposed booster extraction septum magnet
International Nuclear Information System (INIS)
To improve the performance of Indus-2 storage ring, it is planned to operate the booster injector at beam energy of 700 MeV, which is presently being operated at 550 MeV. At higher beam energy the beam size will increase and quality of extracted beam from booster will be deteriorated because of the poor magnetic field homogeneity of existing septum magnet. As a consequence it may reduce the injection efficiency of Indus-2. In this perspective, magnetic field homogeneity and good field region of the extraction septum magnet plays a vital role. Thus it is required to upgrade the technical specification of the booster extraction septum magnet. The same has been evolved and its results are presented. (author)
Analysis of Static and Dynamic Behavior of T-shape Beam Reinforced by External Prestressing Tendon
Directory of Open Access Journals (Sweden)
Dinghai Li
2013-01-01
Full Text Available External prestressing has become a primary method for strengthening existing concrete beam and has been increasingly used in the construction of newly erected ones, particularly railroad bridges in recent years. In order to evaluate the effect of this method, the static and dynamic behavior of a T-frame beam reinforced by external prestressed strengthened concrete beam was analyzed by 3D finite element method, and the field test study was also made. The study was carried out to further investigate the simply supported reinforced prestressed concrete beam strengthened by external prestressing through theory analysis and experiment.
Crossed molecular beam studies of atmospheric chemical reaction dynamics
Energy Technology Data Exchange (ETDEWEB)
Zhang, Jingsong
1993-04-01
The dynamics of several elementary chemical reactions that are important in atmospheric chemistry are investigated. The reactive scattering of ground state chlorine or bromine atoms with ozone molecules and ground state chlorine atoms with nitrogen dioxide molecules is studied using a crossed molecular beams apparatus with a rotatable mass spectrometer detector. The Cl + O{sub 3} {yields} ClO + O{sub 2} reaction has been studied at four collision energies ranging from 6 kcal/mole to 32 kcal/mole. The derived product center-of-mass angular and translational energy distributions show that the reaction has a direct reaction mechanism and that there is a strong repulsion on the exit channel. The ClO product is sideways and forward scattered with respect to the Cl atom, and the translational energy release is large. The Cl atom is most likely to attack the terminal oxygen atom of the ozone molecule. The Br + O{sub 3} {yields} ClO + O{sub 2} reaction has been studied at five collision energies ranging from 5 kcal/mole to 26 kcal/mole. The derived product center-of-mass angular and translational energy distributions are quite similar to those in the Cl + O{sub 3} reaction. The Br + O{sub 3} reaction has a direct reaction mechanism similar to that of the Cl + O{sub 3} reaction. The electronic structure of the ozone molecule seems to play the central role in determining the reaction mechanism in atomic radical reactions with the ozone molecule. The Cl + NO{sub 2} {yields} ClO + NO reaction has been studied at three collision energies ranging from 10.6 kcal/mole to 22.4 kcal/mole. The center-of-mass angular distribution has some forward-backward symmetry, and the product translational energy release is quite large. The reaction proceeds through a short-lived complex whose lifetime is less than one rotational period. The experimental results seem to show that the Cl atom mainly attacks the oxygen atom instead of the nitrogen atom of the NO{sub 2} molecule.
Injector Beam Dynamics for a High-Repetition Rate 4th-Generation Light Source
Energy Technology Data Exchange (ETDEWEB)
Papadopoulos, C. F.; Corlett, J.; Emma, P.; Filippetto, D.; Penn, G.; Qiang, J.; Reinsch, M.; Sannibale, F.; Steier, C.; Venturini, M.; Wells, R.
2013-05-20
We report on the beam dynamics studies and optimization methods for a high repetition rate (1 MHz) photoinjector based on a VHF normal conducting electron source. The simultaneous goals of beamcompression and reservation of 6-dimensional beam brightness have to be achieved in the injector, in order to accommodate a linac driven FEL light source. For this, a parallel, multiobjective optimization algorithm is used. We discuss the relative merits of different injector design points, as well as the constraints imposed on the beam dynamics by technical considerations such as the high repetition rate.
Beam dynamics and commissioning of low and medium energy H- beam at Linac4
Satri, Masoomeh Yarmohammadi; Lamehi-Rachti , Mohammad
The First step of the CERN Large Hadron Collider injectors upgrade (LIU) project is Linac4. It accelerates H- ions to 160 MeV in an 80 m long accelerator housed in a tunnel 12 m underground, presently under construction. It will replace the present 50 MeV proton Linac2 as injector of the proton accelerator complex to increase the LHC luminosity. It consists of a 45 keV RF volume source, a twosolenoid Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) accelerating the beam to 3 MeV, a Medium Energy Beam Transport (MEBT) line. The MEBT houses a fast chopper to selectively remove unwanted micro-bunches in the 352 MHz sequence and avoid losses at capture in the CERN PSB (1 MHz). After chopping, the beam acceleration continues by a 50 MeV Drift Tube Linac (DTL), a 100 MeV Cell-Coupled Drift Tube Linac and a Pi-Mode Structure bringing the beam to the final energy of 160 MeV. Linac4 has been commissioned with a temporary source up to 12 MeV. The beam commissioning stages of Linac4 in LEBT...
Isospin aspects in nuclear reactions involving Ca beams at 25 MeV/nucleon
Energy Technology Data Exchange (ETDEWEB)
Lombardo, I., E-mail: ilombardo@lns.infn.it; Agodi, C.; Alba, R.; Amorini, F.; Anzalone, A. [INFN Laboratori Nazionali del Sud (Italy); Auditore, L. [Universita di Messina, and INFN-Gr. Coll. Messina, Dipartimento di Fisica (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering (Romania); Cardella, G. [INFN, Sezione di Catania (Italy); Cavallaro, S. [INFN Laboratori Nazionali del Sud (Italy); Chatterjee, M. B. [Saha Institute of Nuclear Physics (India); Filippo, E. De [INFN, Sezione di Catania (Italy); Di Pietro, A.; Figuera, P. [INFN Laboratori Nazionali del Sud (Italy); Giuliani, G.; Geraci, E.; Grassi, L. [Dipartimento di Fisica e Astronomia Universita di Catania (Italy); Grzeszczuk, A. [University of Silesia, Institute of Physics (Poland); Han, J. [INFN Laboratori Nazionali del Sud (Italy); La Guidara, E. [INFN, Sezione di Catania (Italy); Lanzalone, G. [INFN Laboratori Nazionali del Sud (Italy); and others
2011-11-15
Isospin dependence of dynamical and thermodynamical properties observed in reactions {sup 40}Ca+ {sup 40,48}Ca and {sup 40}Ca + {sup 46}Ti at 25 MeV/nucleon has been studied. We used the CHIMERA multi-detector array. Strong isospin effects are seen in the isotopic distributions of light nuclei and in the competition between different reaction mechanisms in semi-central collisions. We will show also preliminary results obtained in nuclear collision {sup 48}Ca + {sup 48}Ca at 25MeV/nucleon, having very high N/Z value in the entrance channel (N/Z = 1.4). The enhancement of evaporation residue production confirms the strong role played by the N/Z degree of freedom in nuclear dynamics.
A particle-in-cell mode beam dynamics simulation of medium energy beam transport for the SSC-Linac
Institute of Scientific and Technical Information of China (English)
XIAO Chen; XU Meng-Xin; HE Shou-Bo; XIA Jia-Wen; HE Yuan; YUAN You-Jin; LU Yuan-Rong; LIU Yong; WANG Zhi-Jun; DU Xiao-Nan; YAO Qing-Gao; LIU Ge
2012-01-01
A new linear accelerator system,called the SSC-Linac injector,is being designed at HIRFL (the heavy ion research facility of Lanzhou).As part of the SSC-Linac,the medium energy beam transport (MEBT) consists of seven magnetic quadrupoles,a re-buncher and a diagnose box.The total length of this segment is about 1.75 m.The beam dynamics simulation in MEBT has been studied using the TRACK 3D particlein-cell code,and the simulation result shows that the beam accelerated from the radio frequency quadrupole (RFQ) matches well with the acceptance of the following drift tube linac (DTL) in both the transverse and longitudinal phase spaces,and that most of the particles can be captured by the final sector focusing cyclotronfor further acceleration.The longitudinal emittance of the RFQ and the longitudinal acceptance of the DTL was calculated in detail,and a multi-particle beam dynamics simulation from the ion source to the end of the DTL was done to verify the original design.
A particle-in-cell mode beam dynamics simulation of medium energy beam transport for the SSC-Linac
Xiao, Chen; He, Yuan; Yuan, You-Jin; Lu, Yuan-Rong; Liu, Yong; Wang, Zhi-Jun; Du, Xiao-Nan; Yao, Qing-Gao; Liu, Ge; Xu, Meng-Xin; He, Shou-Bo; Xia, Jia-Wen
2012-01-01
A new linear accelerator system, called the SSC-Linac injector, is being designed at HIRFL (the heavy ion research facility of Lanzhou). As part of the SSC-Linac, the medium energy beam transport (MEBT) consists of seven magnetic quadrupoles, a re-buncher and a diagnose box. The total length of this segment is about 1.75 m. The beam dynamics simulation in MEBT has been studied using the TRACK 3D particle-in-cell code, and the simulation result shows that the beam accelerated from the radio frequency quadrupole (RFQ) matches well with the acceptance of the following drift tube linac (DTL) in both the transverse and longitudinal phase spaces, and that most of the particles can be captured by the final sector focusing cyclotron for further acceleration. The longitudinal emittance of the RFQ and the longitudinal acceptance of the DTL was calculated in detail, and a multi-particle beam dynamics simulation from the ion source to the end of the DTL was done to verify the original design.
DTL cavity design and beam dynamics for a TAC linear proton accelerator
Caliskan, A.; Yılmaz, M.
2012-02-01
A 30 mA drift tube linac (DTL) accelerator has been designed using SUPERFISH code in the energy range of 3-55 MeV in the framework of the Turkish Accelerator Center (TAC) project. Optimization criteria in cavity design are effective shunt impedance (ZTT), transit-time factor and electrical breakdown limit. In geometrical optimization we have aimed to increase the energy gain in each RF gap of the DTL cells by maximizing the effective shunt impedance (ZTT) and the transit-time factor. Beam dynamics studies of the DTL accelerator have been performed using beam dynamics simulation codes of PATH and PARMILA. The results of both codes have been compared. In the beam dynamical studies, the rms values of beam emittance have been taken into account and a low emittance growth in both x and y directions has been attempted.
DTL cavity design and beam dynamics for a TAC linear proton accelerator
Institute of Scientific and Technical Information of China (English)
A. Caliskan; M. Yi1maz
2012-01-01
A 30 mA drift tube linac (DTL) accelerator has been designed using SUPERFISH code in the energy range of 3-55 MeV in the framework of the Turkish Accelerator Center (TAC) project.Optimization criteria in cavity design are effective shunt impedance (ZTT),transit-time factor and electrical breakdown limit.In geometrical optimization we have aimed to increase the energy gain in each RF gap of the DTL cells by maximizing the effective shunt impedance (ZTT) and the transit-time factor.Beam dynamics studies of the DTL accelerator have been performed using beam dynamics simulation codes of PATH and PARMILA.The results of both codes have been compared.In the beam dynamical studies,the rms values of beam emittance have been taken into account and a low emittance growth in both x and y directions has been attempted.
Modeled and Measured Dynamics of a Composite Beam with Periodically Varying Foam Core
Cabell, Randolph H.; Cano, Roberto J.; Schiller, Noah H.; Roberts Gary D.
2012-01-01
The dynamics of a sandwich beam with carbon fiber composite facesheets and foam core with periodic variations in material properties are studied. The purpose of the study is to compare finite element predictions with experimental measurements on fabricated beam specimens. For the study, three beams were fabricated: one with a compliant foam core, a second with a stiffer core, and a third with the two cores alternating down the length of the beam to create a periodic variation in properties. This periodic variation produces a bandgap in the frequency domain where vibrational energy does not readily propagate down the length of the beam. Mode shapes and natural frequencies are compared, as well as frequency responses from point force input to velocity response at the opposite end of the beam.
Gas dynamics considerations in a non-invasive profile monitor for charged particle beams
Tzoganis, Vasilis; Welsch, Carsten P
2014-01-01
A non-invasive, gas jet-based, beam profile monitor has been developed in the QUASAR Group at the Cockcroft Institute, UK. This allows on-line measurement of the 2-dimensional transverse profile of particle beams with negligible disturbance to either primary beam or accelerator vacuum. The monitor is suitable for use with beams across a wide range of energies and intensities. In this setup a nozzle-skimmer system shapes a thin supersonic gas jet into a curtain. However, the small dimensions of the gas inlet nozzle and subsequent skimmers were shown to be the cause of many operational problems. In this paper, the dynamics of gas jet formation transport and shaping is discussed before an image-processing based alignment technique is introduced. Furthermore, experimental results obtained with a 5 keV electron beam are discussed and the effects of gas stagnation pressure on the acquired beam are presented.
Radiosensitivity of cancer cells against carbon-ion beams in an aspect of the p53 gene status
International Nuclear Information System (INIS)
We can easily understand that radiation sensitivities of cancer cells are dependent on the status of cancer-related genes. It is important to clarify which genes affect radiation sensitivity and reflect the effectiveness of radiation therapy for cancer cells. We have studied about the function of a tumor suppressor gene of p53, because p53 controls apoptosis, cell cycle and DNA repair from an aspect of important roles in cell fate. By analysis of function of p53 gene, therefore, we aim to predict the therapeutic effectiveness and to select the modalities of cancer therapies such as radiotherapy, chemotherapy and hyperthermia. As a final goal, we want to accept the most effective therapy, namely tailor-made cancer therapy, for each patient. Here, we introduce that carbon-beam therapy induced the expression of p53-independent apoptosis-related genes and NO radicals in mutated p53 cancer cells. (author)
Saakian, David B
2009-01-01
The parallel mutation-selection evolutionary dynamics, in which mutation and replication are independent events, is solved exactly in the case that the Malthusian fitnesses associated to the genomes are described by the Random Energy Model (REM) and by a ferromagnetic version of the REM. The solution method uses the mapping of the evolutionary dynamics into a quantum Ising chain in a transverse field and the Suzuki-Trotter formalism to calculate the transition probabilities between configurations at different times. We find that in the case of the REM landscape the dynamics can exhibit three distinct regimes: pure diffusion or stasis for short times, depending on the fitness of the initial configuration, and a spin-glass regime for large times. The dynamic transition between these dynamical regimes is marked by discontinuities in the mean-fitness as well as in the overlap with the initial reference sequence. The relaxation to equilibrium is described by an inverse time decay. In the ferromagnetic REM, we find...
Beam dynamics and optics studies for the LHC injectors upgrade
Bartosik, Hannes; Benedikt, Michael
The Large Hadron Collider (LHC) upgrade, which aims at reaching signiﬁcantly higher luminosities at the experiment sites, requires the existing injector chain to provide proton beams with unprecedented beam intensity and brightness. The required beam parameters are out of reach for the CERN accelerator complex in its present state. Therefore, upgrade possibilities of the existing injectors for mitigating their performance limitations or their partial replacement by new machines have been studied. The transition energy plays a central role for the performance of synchrotrons. Designing a lattice with negative momentum compaction (NMC), i.e. imaginary transition energy, allows avoiding transition crossing and thus the associated performance limitations. In the ﬁrst part of this thesis, the properties of an NMC cell are studied. The limits of betatron stability are evaluated by a combination of analytical and numerical calculations. The NMC cell is then used for the design study of a new synchrotron called P...
Dynamics of ion beam charge neutralization by ferroelectric plasma sources
Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.
2016-04-01
Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established ˜5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-μs surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of μs after the high voltage pulse is applied. It is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.
Chaotic ray dynamics in an optical cavity with a beam splitter
Puentes, G; Woerdman, J P
2003-01-01
We investigate the ray dynamics in an optical cavity when a ray splitting mechanism is present. The cavity is a conventional two-mirror stable resonator and the ray splitting is achieved by inserting an optical beam splitter perpendicular to the cavity axis. Using Hamiltonian optics, we show that such a simple device presents a surprisingly rich chaotic ray dynamics.
Egorov, E. N.; Koronovskii, A. A.; Kurkin, S. A.; Hramov, A. E.
2013-11-01
Results of numerical simulations and analysis of the formation and nonlinear dynamics of the squeezed state of a helical electron beam in a vircator with a magnetron injection gun as an electron source and with additional electron deceleration are presented. The ranges of control parameters where the squeezed state can form in such a system are revealed, and specific features of the system dynamics are analyzed. It is shown that the formation of a squeezed state of a nonrelativistic helical electron beam in a system with electron deceleration is accompanied by low-frequency longitudinal dynamics of the space charge.
Energy Technology Data Exchange (ETDEWEB)
Egorov, E. N., E-mail: evgeniy.n.egorov@gmail.com; Koronovskii, A. A.; Kurkin, S. A.; Hramov, A. E. [Chernyshevsky Saratov State University (Russian Federation)
2013-11-15
Results of numerical simulations and analysis of the formation and nonlinear dynamics of the squeezed state of a helical electron beam in a vircator with a magnetron injection gun as an electron source and with additional electron deceleration are presented. The ranges of control parameters where the squeezed state can form in such a system are revealed, and specific features of the system dynamics are analyzed. It is shown that the formation of a squeezed state of a nonrelativistic helical electron beam in a system with electron deceleration is accompanied by low-frequency longitudinal dynamics of the space charge.
Beam Dynamics Studies for High-Intensity Beams in the CERN Proton Synchrotron
AUTHOR|(CDS)2082016; Benedikt, Michael
With the discovery of the Higgs boson, the existence of the last missing piece of the Standard Model of particle physics (SM) was confirmed. However, even though very elegant, this theory is unable to explain, for example, the generation of neutrino masses, nor does it account for dark energy or dark matter. To shed light on some of these open questions, research in fundamental particle physics pursues two complimentary approaches. On the one hand, particle colliders working at the high-energy frontier, such as the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN), located in Geneva, Switzerland, are utilized to investigate the fundamental laws of nature. Alternatively, fixed target facilities require high-intensity beams to create a large flux of secondary particles to investigate, for example, rare particle decay processes, or to create neutrino beams. This thesis investigates limitations arising during the acceleration of high-intensity beams at the CERN Proton Synchrotro...
Pseudo Slice Energy Spread in Dynamics of Electron Beams Moving through Magnetic Bends
Li, Rui
2014-01-01
In the previous canonical formulation of beam dynamics for an electron bunch moving ultrarelativistically through magnetic bending systems, we have shown that the transverse dynamics equation for a particle in the bunch has a driving term which behaves as the centrifugal force caused by the particle's initial potential energy due to collective particle interactions within the bunch. As a result, the initial potential energy at the entrance of a bending system, which we call pseudo (kinetic) energy, is indistinguishable from the usual kinetic energy offset from the design energy in its perturbation to particle optics through dispersion and momentum compaction. In this paper, in identifying this centrifugal force on particles as the remnant of the CSR cancellation effect in transverse particle dynamics, we show how the dynamics equation in terms of the canonical momentum for beam motion on a curved orbit is related to the Panofsky-Wenzel theorem for wakefields for beam motion on a straight path. It is shown tha...
Dynamic Response of Axially Loaded Euler-Bernoulli Beams
DEFF Research Database (Denmark)
Bayat, M.; Barari, Amin; Shahidi, M.
2011-01-01
The current research deals with application of a new analytical technique called Energy Balance Method (EBM) for a nonlinear problem. Energy Balance Method is used to obtain the analytical solution for nonlinear vibration behavior of Euler-Bernoulli beams subjected to axial loads. Analytical...
Dynamic modeling and analysis of the PZT-bonded composite Timoshenko beams: Spectral element method
Lee, Usik; Kim, Daehwan; Park, Ilwook
2013-03-01
The health of thin laminated composite beams is often monitored using the ultrasonic guided waves excited by wafer-type piezoelectric transducers (PZTs). Thus, for the smart composite beams which consist of a laminated composite base beam and PZT layers, it is very important to develop a very reliable mathematical model and to use a very accurate computational method to predict accurate dynamic characteristics at very high ultrasonic frequency. In this paper, the axial-bending-shear-lateral contraction coupled differential equations of motion are derived first by the Hamilton's principle with Lagrange multipliers. The smart composite beam is represented by a Timoshenko beam model by adopting the first-order shear deformation theory (FSDT) for the laminated composite base beam. The axial deformation of smart composite beam is improved by taking into account the effects of lateral contraction by adopting the concept of Mindlin-Herrmann rod theory. The spectral element model is then formulated by the variation approach from coupled differential equations of motion transformed into the frequency domain via the discrete Fourier transform. The high accuracy of the present spectral element model is verified by comparing with other solution methods: the finite element model developed in this paper and the commercial FEA package ANSYS. Finally the dynamics and wave characteristics of some example smart composite beams are investigated through the numerical studies.
Static and dynamic testing of a damaged post tensioned concrete beam
Directory of Open Access Journals (Sweden)
Limongelli M.P.
2015-01-01
Full Text Available In this paper are reported the results of an experimental campaign carried out on a post tensioned concrete beam with the aim of investigating the possibility to detect early warning signs of deterioration basing on static and/or dynamic tests. The beam was tested in several configurations aimed to reproduce several different phases of the ‘life’ of the beam: the original undamaged state, increasing loss of tension in the post tensioning cables, a strengthening intervention carried out by means of a second tension cable, formation of further cracks on the strengthened beam. Responses of the beam were measured by an extensive set of instruments consisting of accelerometers, inclinometers, displacement transducers, strain gauges and optical fibres. The paper discusses the tests program and the dynamic characterization of the beam in the different damage scenarios. The modal properties of the beam in the different phases were recovered basing on the responses recorded on the beam during sine-sweep and impact hammer tests. The variation of the first modal frequency was studied to investigate the sensitivity of this parameter to both the cracking of the concrete section and the tension in the cables and also to compare results given by different types of experimental tests.
The structural and dynamical aspects of boron nitride nanotubes under high velocity impacts.
Machado, Leonardo D; Ozden, Sehmus; Tiwary, ChandraSekhar; Autreto, Pedro A S; Vajtai, Robert; Barrera, Enrique V; Galvao, Douglas S; Ajayan, Pulickel M
2016-06-01
This communication report is a study on the structural and dynamical aspects of boron nitride nanotubes (BNNTs) shot at high velocities (∼5 km s(-1)) against solid targets. The experimental results show unzipping of BNNTs and the formation of hBN nanoribbons. Fully atomistic reactive molecular dynamics simulations were also carried out to gain insights into the BNNT fracture patterns and deformation mechanisms. Our results show that longitudinal and axial tube fractures occur, but the formation of BN nanoribbons from fractured tubes was only observed for some impact angles. Although some structural and dynamical features of the impacts are similar to the ones reported for CNTs, because BNNTs are more brittle than CNTs this results in a larger number of fractured tubes but with fewer formed nanoribbons. PMID:27189765
Beam dynamics studies on the stored proton beam in the SPS
Boussard, Daniel; Gareyte, Jacques; Graziani, C; Linnecar, Trevor Paul R; Scandale, Walter; Thomas, D; CERN. Geneva
1980-01-01
Recent improvements to the low-level radiofrequency system have resulted in a considerable increase in bunched beam lifetime. Single proton bunches have been stored for up to 18 hours. In the course of these studies, new instrumentation has been developed and other experiments relevant to pp operation have been performed. (9 refs).
Strength and behavior in shear of reinforced concrete deep beams under dynamic loading conditions
International Nuclear Information System (INIS)
Highlights: ► Effects of wider range of loading rates on dynamic shear behavior of RC deep beams. ► Experimental investigation of RC deep beam with and without shear reinforcements. ► Verification of experimental results with truss model and FE simulation results. ► Empirical equations are proposed to predict the dynamic increase factor of maximum resistance. -- Abstract: Research on reinforced concrete (RC) deep beams has seen considerable headway over the past three decades; however, information on the dynamic shear strength and behavior of RC deep beams under varying rates of loads remains limited. This paper describes the experimental results of 24 RC deep beams with and without shear reinforcements under varying rates of concentrated loading. Results obtained serve as useful data on shear resistance, failure patterns and strain rates corresponding to varying loading rates. An analytical truss model approach proves its efficacy in predicting the dynamic shear resistance under varying loading rates. Furthermore, three-dimensional nonlinear finite element (FE) model is described and the simulation results are verified with the experimental results. A parametric study is then conducted to investigate the influence of longitudinal reinforcement ratio, transverse reinforcement ratio and shear span to effective depth ratio on shear behavior. Subsequently, two empirical equations were proposed by integrating the various parameters to assess the dynamic increase factor (DIF) of maximum resistance under varying rates of concentrated loading
Strength and behavior in shear of reinforced concrete deep beams under dynamic loading conditions
Energy Technology Data Exchange (ETDEWEB)
Adhikary, Satadru Das [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Li, Bing, E-mail: cbli@ntu.edu.sg [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Fujikake, Kazunori [Department of Civil and Environmental Engineering, National Defense Academy, Yokosuka 239 8686 (Japan)
2013-06-15
Highlights: ► Effects of wider range of loading rates on dynamic shear behavior of RC deep beams. ► Experimental investigation of RC deep beam with and without shear reinforcements. ► Verification of experimental results with truss model and FE simulation results. ► Empirical equations are proposed to predict the dynamic increase factor of maximum resistance. -- Abstract: Research on reinforced concrete (RC) deep beams has seen considerable headway over the past three decades; however, information on the dynamic shear strength and behavior of RC deep beams under varying rates of loads remains limited. This paper describes the experimental results of 24 RC deep beams with and without shear reinforcements under varying rates of concentrated loading. Results obtained serve as useful data on shear resistance, failure patterns and strain rates corresponding to varying loading rates. An analytical truss model approach proves its efficacy in predicting the dynamic shear resistance under varying loading rates. Furthermore, three-dimensional nonlinear finite element (FE) model is described and the simulation results are verified with the experimental results. A parametric study is then conducted to investigate the influence of longitudinal reinforcement ratio, transverse reinforcement ratio and shear span to effective depth ratio on shear behavior. Subsequently, two empirical equations were proposed by integrating the various parameters to assess the dynamic increase factor (DIF) of maximum resistance under varying rates of concentrated loading.
Electromagnetic and beam dynamics studies of a high current drift tube linac for LEHIPA
Roy, S.; Rao, S. V. L. S.; Pande, R.; Krishnagopal, S.; Singh, P.
2014-06-01
We have performed detailed electromagnetic and beam dynamics studies of a 352.21 MHz drift-tube linac (DTL) that will accelerate a 30 mA CW proton beam from 3 to 20 MeV. At such high currents space charge effects are important, and therefore the effect of linear as well as non-linear space charge has been studied (corresponding to uniform and Gaussian initial beam distributions), in order to avoid space charge instabilities. To validate the electromagnetic simulations, a 1.2 m long prototype of the DTL was fabricated. RF measurements performed on the prototype were in good agreement with the simulations. A detailed simulation study of beam halos was also performed, which showed that beyond a current of 10 mA, significant longitudinal beam halos are excited even for a perfectly matched beam, whereas for a mis-matched beam transverse beam halos are also excited. However, these do not lead to any beam loss within the DTL.
Beam Dynamics Based Design of Solenoid Channel for TAC Proton Linac
Kisoglu, H F
2014-01-01
Today a linear particle accelerator (linac), in which electric and magnetic fields are of vital importance, is one of the popular energy generation sources like Accelerator Driven System (ADS). A multipurpose, including primarily ADS, proton linac with energy of ~2 GeV is planned to constitute within the Turkish Accelerator Center (TAC) project collaborated by more than 10 Turkish universities. A Low Energy Beam Transport (LEBT) channel with two solenoids is a subcomponent of this linac. It transports the proton beam ejected by an ion source, and matches it with the Radio Frequency Quadrupole (RFQ) that is an important part of the linac. The LEBT channel would be consisted of two focusing solenoids and some diagnostic elements such as faraday cup, BC transformers, etc. This paper includes a beam dynamical design and optimization study of LEBT channel for TAC proton linac done by using a beam dynamics simulation code PATH MANAGER and comparing of the simulation results with the theoretical expectations.
An exact dynamic stiffness matrix for axially loaded double-beam systems
Indian Academy of Sciences (India)
Li Xiaobin; Xu Shuangxi; Wu Weiguo; Li Jun
2014-06-01
An exact dynamic stiffness method is presented in this paper to determine the natural frequencies and mode shapes of the axially loaded double-beam systems,which consist of two homogeneous and prismatic beams with a distributed spring in parallel between them.The effects of the axial force, shear deformation and rotary inertia are considered, as shown in the theoretical formulation. The dynamic stiffness influence coefficients are formulated from the governing differential equations of the axially loaded double-beam system in free vibration by using the Laplace transform method. An example is given to demonstrate the effectiveness of this method, in which ten boundary conditions are investigated and the effect of the axial force on the natural frequencies and mode shapes of the double-beam system are further discussed.
The Flow Field Downstream of a Dynamic Low Aspect Ratio Circular Cylinder: A Parametric Study
Gildersleeve, Samantha; Dan, Clingman; Amitay, Michael
2015-11-01
Flow past a static, low aspect ratio cylinder (pin) has shown the formation of vortical structures, namely the horseshoe and arch-type vortex. These vortical structures may have substantial effects in controlling flow separation over airfoils. In the present experiments, the flow field associated with a low aspect ratio cylinder as it interacts with a laminar boundary layer under static and dynamic conditions was investigated through a parametric study over a flat plate. As a result of the pin being actuated in the wall-normal direction, the structures formed in the wake of the pin were seen to be a strong function of actuation amplitude, driving frequency, and aspect ratio of the cylinder. The study was conducted at a Reynolds number of 1875, based on the local boundary layer thickness, with a free stream velocity of 10 m/s. SPIV data were collected for two aspect ratios of 0.75 and 1.125, actuation amplitudes of 6.7% and 16.7%, and driving frequencies of 175 Hz and 350 Hz. Results indicate that the presence and interactions between vortical structures are altered in comparison to the static case and suggest increased large-scale mixing when the pin is driven at the shedding frequency (350 Hz). Supported by the Boeing Company.
Structural dynamic response of target container against proton beam
Energy Technology Data Exchange (ETDEWEB)
Kikuchi, Kenji; Ishikura, Syuichi; Futakawa, Masatoshi; Hino, Ryutaro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1997-11-01
Stress waves were analyzed for a target container of neutron science research project using a high-intensity proton accelerator that generates high energy and high current proton beam. In the mercury target, the pulsed proton beam generates intense power density in the course of spallation reaction and causes pressure wave in the mercury and stress wave in the target container due to a sudden temperature change. Structural integrity of the target container depends on the power intensity at a maximum energy deposit. A broad proton profile is favorable to the structural assessment of the container rather than narrow one. Stress wave have propagated in the target container at a speed of sound. It only takes 0.1 ms for the size of 40 cm length stainless steel container. Further assessment is necessary to optimize a geometry of the container and establish a method to evaluate a life time. (author)
Experimental Dynamic Analysis of Nonlinear Beams under Moving Loads
Directory of Open Access Journals (Sweden)
A. Bellino
2012-01-01
Full Text Available It is well known that nonlinear systems, as well as linear time-varying systems, are characterized by non-stationary response signals. In this sense, they both show natural frequencies that are not constant over time; this variation has however different origins: for a time-varying system the mass, and possibly the stiffness distributions, are changing over time, while for a nonlinear system the natural frequencies are amplitude-dependent. An interesting case of time-varying system occurs when analyzing the transit of a train over a railway bridge, easily simulated by the crossing of a moving load over a beam. In this case, the presence of a nonlinearity in the beam behaviour can cause a significant alteration of the modal parameters extracted from the linearized model, such that the contributions of the two effects are no more distinguishable.
LHeC ERL Design and Beam-dynamics Issues
Bogacz, S A; Zimmermann, F; Schulte, D
2011-01-01
We discuss machine and beam parameter choices for a Linac-Ring option of the Large Hadron electron Collider (LHeC) based on the LHC [1]. With the total wall-plug power limited to 100 MW and a target current of about 6 mA the desired luminosity of 1033 cm-2s-1 can be reached, providing one exploits unique features of the Energy Recovery Linac (ERL). We describe the overall layout of such ERL complex located on the LHC site. Multi-pass linac optics enabling operation of the proposed 3-pass Recirculating Linear Accelerator (RLA) in the Energy Recovery mode is presented. We also describe emittance preserving return arc optics architecture; including layout and optics of the arc switchyard. Furthermore, we discuss importance of collective effects such as multi-pass beam breakup instability (BBU) in ERL.
A computational procedure for multibody systems including flexible beam dynamics
Downer, J. D.; Park, K. C.; Chiou, J. C.
1990-01-01
A computational procedure suitable for the solution of equations of motions for flexible multibody systems has been developed. The flexible beams are modeled using a fully nonlinear theory which accounts for both finite rotations and large deformations. The present formulation incorporates physical measures of conjugate Cauchy stress and covariant strain increments. As a consequence, the beam model can easily be interfaced with real-time strain measurements and feedback control systems. A distinct feature of the present work is the computational preservation of total energy for undamped systems; this is obtained via an objective strain increment/stress update procedure combined with an energy-conserving time integration algorithm which contains an accurate update of angular orientations. The procedure is demonstrated via several example problems.
Dynamic Nonlinear Focal Shift in Amplitude Modulated Moderately Focused Acoustic Beams
Jiménez, Noé; González-Salido, Nuria
2016-01-01
The phenomenon of the displacement of the position of the pressure, intensity and acoustic radiation force maxima along the axis of focused acoustic beams under increasing driving amplitudes (nonlinear focal shift) is studied for the case of a moderately focused beam excited with continuous and 25 kHz amplitude modulated signals, both in water and tissue. We prove that in amplitude modulated beams the linear and nonlinear propagation effects coexist in a semi-period of modulation, giving place to a complex dynamic behaviour, where the singular points of the beam (peak pressure, rarefaction, intensity and acoustic radiation force) locate at different points on axis as a function of time. These entire phenomena are explained in terms of harmonic generation and absorption during the propagation in a lossy nonlinear medium both, for a continuous and an amplitude modulated beam. One of the possible applications of the acoustic radiation force displacement is the generation of shear waves at different locations by ...
Non-Gaussian beam dynamics in low energy antiproton storage rings
Resta-López, J.; Hunt, J. R.; Welsch, C. P.
2016-10-01
In low energy antiproton facilities, where electron cooling is fundamental, the cooling forces together with heating phenomena causing emittance blow-up, such as Intra Beam Scattering (IBS), result in highly non-Gaussian beam distributions. In these cases, a precise simulation of IBS effects is essential to realistically evaluate the long term beam evolution, taking into account the non-Gaussian characteristics of the beam. Here, we analyse the beam dynamics in the Extra Low ENergy Antiproton ring (ELENA), which is a new small synchrotron currently being constructed at CERN to decelerate antiprotons to energies as low as 100 keV. Simulations are performed using the code BETACOOL, comparing different models of IBS.
Simulation of Electron Beam Dynamics in a Nonmagnetized High-Current Vacuum Diode
Anishchenko, Sergey
2016-01-01
The electron beam dynamics in a nonmagnetized high-current vacuum diode is analyzed for different cathode-anode gap geometries. The conditions enabling to achieve the minimal {initial} momentum spread in the electron beam are found out. A drastic rise of current density in a vacuum diode with a ring-type cathode is described. The effect is shown to be caused by electrostatic repulsion.
On the study of the dynamical aspects of parasitemia in the blood cycle of malaria
Zorzenon Dos Santos, R. M.; Pinho, S. T. R.; Ferreira, C. P.; da Silva, P. C. A.
2007-04-01
Malaria is an important cause of morbidity and mortality worldwide. One striking aspect regarding malaria is the fact that individuals living in endemic areas do not develop immunity against the parasite, falling ill whenever they are exposed to the parasite. The understanding of why immunity is not developed in the usual way against Plasmodium is crucial to the improvement of treatment and prevention. In this work, we study some aspects of the dynamics of the blood cycle of malaria using both modelling and data analysis of observed case-histories described by parasitemia time series. By comparing our simulations with experimental results we have shown that the different behaviour observed among patients may be associated to differences in the efficiency of the immune system to control the infection.
Large deflection dynamic response analysis of flexible hull beams by the multibody system method
Zhang, Xiaojun; Wu, Guorong
2007-04-01
In this paper the large deflection dynamic problems of Euler beams are investigated. The vibration control equations are derived based on the multibody system method. A numerical procedure for solving the resulting differential algebraic equations is presented on the basis of the Newmark direct integration method combined with the Newton-Raphson iterative method. The sub beams are treated as small deformation in the convected coordinate systems, which can greatly simplify the deformation description. The rigid motions of the sub beams are taken into account through the motions of the convected coordinate systems. Numerical examples are carried out, where results show the effectiveness of the proposed method.
Large Deflection Dynamic Response Analysis of Flexible Hull Beams by the Multibody System Method
Institute of Scientific and Technical Information of China (English)
ZHANG Xiaojun; WU Guorong
2007-01-01
In this paper the large deflection dynamic problems of Euler beams are investigated. The vibration control equations are derived based on the multibody system method. A numerical procedure for solving the resulting differential algebraic equations is presented on the basis of the Newmark direct integration method combined with the Newton-Raphson iterative method. The sub beams are treated as small deformation in the convected coordinate systems, which can greatly simplify the deformation description. The rigid motions of the sub beams are taken into account through the motions of the convected coordinate systems. Numerical examples are carried out, where results show the effectiveness of the proposed method.
Beam dynamics studies and parametric characterization of a standing wave electron linac
Dash, R.; Mondal, J.; Sharma, A.; Mittal, K. C.
2013-07-01
This paper presents the results of electron beam tracking simulations for a 30 MeV standing wave electron linac at Electron Beam Centre Kharghar, Navi Mumbai, India. For the pulsed mode operation of the present linac preferential operation parameters have been determined from the results of beam dynamics studies. This electron accelerator is a general purpose facility for generation of Bremsstrahlung X-rays and neutron scattering experiments. This electron accelerator-based experimental neutron facility will be used for measurement of neutron cross-section (n,γ), (n, xn) and (n, f) reactions at different energies for various materials and material irradiation studies.
Concept Modelling of Vehicle Joints and Beam-Like Structures through Dynamic FE-Based Methods
Directory of Open Access Journals (Sweden)
G. De Gaetano
2014-01-01
Full Text Available This paper presents dynamic methodologies able to obtain concept models of automotive beams and joints, which compare favourably with the existing literature methods, in terms of accuracy, easiness of implementation, and computational loads. For the concept beams, the proposed method is based on a dynamic finite element (FE approach, which estimates the stiffness characteristics of equivalent 1D beam elements using the natural frequencies, computed by a modal analysis of the detailed 3D FE model of the structure. Concept beams are then connected to each other by a concept joint, which is obtained through a dynamic reduction technique that makes use of its vibration normal modes. The joint reduction is improved through the application of a new interface beam-to-joint element, able to interpolate accurately the nodal displacements of the outer contour of the section, to obtain displacements and rotations of the central connection node. The proposed approach is validated through an application case that is typical in vehicle body engineering: the analysis of a structure formed by three spot-welded thin-walled beams, connected by a joint.
Dynamic Analysis of a Multibody System Including a Very Flexible Beam Element
Seo, Jong-Hwi; Jung, Il-Ho; Park, Tae-Won; Chai, Jang-Bom
In this paper, the dynamic behavior of a multibody system including very flexible beam elements is presented. The very deformable motion of a beam is demonstrated using absolute nodal coordinate formulation, which is based on finite element procedures, and the general continuum mechanics theory to represent the elastic forces. In order to consider the dynamic interaction between flexible beams and a rigid multibody system, a combined system equation of motion is derived using an absolute nodal coordinate and a rigid body coordinate. In particular, a very flexible catenary cable on which a multibody system moves along its length is presented as a numerical example in this study. To do this, formulations for the sliding joint between a very flexible beam and a rigid body were derived using a non-generalized coordinate, which has no inertia or forces associated with it. This sliding joint is very important to many mechanical applications such as cable cars, pulley systems, and pantograph-catenary system for high-speed trains. In addition, a computation method for the dynamic stress in flexible multibody simulation using an absolute nodal coordinate is presented based on Euler-Bernoulli beam theory, and its reliability was verified by commercial program NASTRAN. Numerical examples are shown using the developed analysis program for flexible multibody systems that include a large deformable beam.
Wang, Yuewu; Wu, Dafang
2016-10-01
Dynamic response of an axially functionally graded (AFG) beam under thermal environment subjected to a moving harmonic load is investigated within the frameworks of classical beam theory (CBT) and Timoshenko beam theory (TBT). The Lagrange method is employed to derive the equations of thermal buckling for AFG beam, and then with the critical buckling temperature as a parameter the Newmark-β method is adopted to evaluate the dynamic response of AFG beam under thermal environments. Admissible functions denoting transverse displacement are expressed in simple algebraic polynomial forms. Temperature-dependency of material constituent is considered. The rule of mixture (Voigt model) and Mori-Tanaka (MT) scheme are used to evaluate the beam's effective material properties. A ceramic-metal AFG beam with immovable boundary condition is considered as numerical illustration to show the thermal effects on the dynamic behaviors of the beam subjected to a moving harmonic load.
Beams dynamics optimisation of LINAC4 structures for increased operational flexibility
Bellodi, G; Garcia Tudela, M; Hein, L M; Lallement, J B; Lombardi, A M; Posocco, P A; Sargsyan, E; Stovall, J
2010-01-01
Linac4 is a new 160 MeV, 40 mA pulsed beam current H- accelerator which will be the source of particles for all proton accelerators at CERN. Construction started in October 2008, and beam commissioning of the 3 MeV front-end is scheduled for early next year. A baseline design of the linac beam dynamics was completed 2 years ago and validated by a systematic campaign of transverse and longitudinal error studies to assess tolerance limits and machine activation levels. Recent studies have been mainly focused on optimising this design to achieve both a smoother performance for nominal beam conditions and to gain operational flexibility for non-nominal scenarios. These include a review of the chopper beam dynamics design, a re-definition of the DTL and CCDTL inter-tank regions and a study of operational schemes for reduced beam currents (either permanent or in pulse-to-pulse mode). These studies have been carried out in parallel to first specifications for a beam commissioning strategy of the linac and its low-en...
Energy Technology Data Exchange (ETDEWEB)
C. L. Bohn (deceased), P. Piot and B. Erdelyi
2008-05-31
According to its original Statement of Work (SOW), the overarching objective of this project is: 'To enhance substantially the understanding of the fundamental dynamics of nonequilibrium high-brightness beams with space charge.' Our work and results over the past three and half years have been both intense and fruitful. Inasmuch as this project is inextricably linked to a larger, growing research program - that of the Beam Physics and Astrophysics Group (BPAG) - the progress that it has made possible cannot easily be separated from the global picture. Thus, this summary report includes major sections on 'global' developments and on those that can be regarded as specific to this project.
New aspects of whistler waves driven by an electron beam studied by a 3-D electromagnetic code
Nishikawa, Ken-Ichi; Buneman, Oscar; Neubert, Torsten
1994-01-01
We have restudied electron beam driven whistler waves with a 3-D electromagnetic particle code. The simulation results show electromagnetic whistler wave emissions and electrostatic beam modes like those observed in the Spacelab 2 electron beam experiment. It has been suggested in the past that the spatial bunching of beam electrons associated with the beam mode may directly generate whistler waves. However, the simulation results indicate several inconsistencies with this picture: (1) whistler waves continue to be generated even after the beam mode space charge modulation looses its coherence, (2) the parallel (to the background magnetic field) wavelength of the whistler wave is longer than that of the beam instability, and (3) the parallel phase velocity of the whistler wave is smaller than that of the beam mode. The complex structure of the whistler waves in the vicinity of the beam suggest that the transverse motion (gyration) of the beam and background electrons is also involved in the generation of whistler waves.
Accessing defect dynamics using intense, nanosecond pulsed ion beams
Persaud, A.; Barnard, J. J.; Guo, H.; Hosemann, P.; Lidia, S.; Minor, A. M.; Seidl, P. A.; Schenkel, T.
2014-01-01
Gaining in-situ access to relaxation dynamics of radiation induced defects will lead to a better understanding of materials and is important for the verification of theoretical models and simulations. We show preliminary results from experiments at the new Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory that will enable in-situ access to defect dynamics through pump-probe experiments. Here, the unique capabilities of the NDCX-II accelerator to gener...
Sánchez-Parcerisa, D; Pourbaix, J C; Ainsley, C G; Dolney, D; Carabe, A
2014-04-01
In proton radiotherapy, the range of particles in the patient body is determined by the energy of the protons. For most systems, the energy selection time is on the order of a few seconds, which becomes a serious obstacle for continuous dose delivery techniques requiring adaptive range modulation. This work analyses the feasibility of using the range modulation wheel, an element in the beamline used to form the spread-out Bragg peak (SOBP), to produce near-instantaneous changes not only in the modulation, but also in the range of the beam. While delivering proton beams in double scattering mode, the beam current can be synchronized with the range modulation wheel rotation by defining a current modulation pattern. Different current modulation patterns were computed from Monte Carlo simulations of our double scattering nozzle to range shift an SOBP of initial range 15 cm by varying degrees of up to ∼9 cm. These patterns were passed to the treatment control system at our institution and the resulting measured depth-dose distributions were analysed in terms of flatness, distal penumbra and relative irradiation time per unit mid-SOBP dose. Suitable SOBPs were obtained in all cases, with the maximum range shift being limited only by the maximum thickness of the wheel. The distal dose fall-off (80% to 20%) of the shifted peaks was broadened to about 1 cm, from the original 0.5 cm, and the predicted overhead in delivery time showed a linear increase with the amount of the shift. By modulating the beam current in clinical scattered proton beams equipped with a modulation wheel, it is possible to dynamically modify the in-patient range of the SOBP without adding any specific hardware or compensators to the beamline. A compromise between sharper distal dose fall-off and lower delivery time can be achieved and is subject to optimization.
Dynamic Response of Inextensible Beams by Improved Energy Balance Method
DEFF Research Database (Denmark)
Sfahani, M. G.; Barari, Amin; Omidvar, M.;
2011-01-01
with a rotationally flexible root and carrying a lumped mass at an intermediate position along its span. Based on the simple EBM, the variational integral of the non-linear conservative system is established, and the Fourier series expansion is employed to address the governing algebraic equations. An alternate......An improved He's energy balance method (EBM) for solving non-linear oscillatory differential equation using a new trial function is presented. The problem considered represents the governing equations of the non-linear, large-amplitude free vibrations of a slender cantilever beam...
DYNAMIC STABILITY OF AXIALLY MOVING VISCOELASTIC BEAMS WITH PULSATING SPEED
Institute of Scientific and Technical Information of China (English)
YANG Xiao-dong; CHEN Li-qun
2005-01-01
Parametric vibration of an axially moving, elastic, tensioned beam with pulsating speed was investigated in the vicinity of subharmonic and combination resonance. The method of averaging was used to yield a set of autonomous equations when the parametric excitation frequency is twice or the combination of the natural frequencies. Instability boundaries were presented in the plane of parametric frequency and amplitude. The analytical results were numerically verified. The effects of the viscoelastic damping, steady speed and tension on the instability boundaries were numerically demonstrated. It is found that the viscoelastic damping decreases the instability regions and the steady speed and the tension make the instability region drift along the frequency axis.
Dynamic boundary controls of a rotating body-beam system with time-varying angular velocity
Boumediène Chentouf
2004-01-01
This paper deals with feedback stabilization of a flexible beam clamped at a rigid body and free at the other end. We assume that there is no damping and the rigid body rotates with a nonconstant angular velocity. To stabilize this system, we propose a feedback law which consists of a control torque applied on the rigid body and either a dynamic boundary control moment or a dynamic boundary control force or both of them applied at the free end of the beam. Then it is ...
Institute of Scientific and Technical Information of China (English)
Song Lei; Yang Hua; Zhang Yang; Zhang Haoyu; Huang Jun
2014-01-01
The influence of dihedral layout on lateral-directional dynamic stability of the tailless flying wing aircraft is discussed in this paper. A tailless flying wing aircraft with a large aspect ratio is selected as the object of study, and the dihedral angle along the spanwise sections is divided into three segments. The influence of dihedral layouts is studied. Based on the stability derivatives cal-culated by the vortex lattice method code, the linearized small-disturbance equations of the lateral modes are used to determine the mode dynamic characteristics. By comparing 7056 configurations with different dihedral angle layouts, two groups of stability optimized dihedral layout concepts are created. Flight quality close to Level 2 requirements is achieved in these optimized concepts without any electric stability augmentation system.
Kinematical and dynamical aspects of higher-spin bound-state equations in holographic QCD
Energy Technology Data Exchange (ETDEWEB)
de Téramond, Guy F.; Dosch, Hans Günter; Brodsky, Stanley J.
2013-04-01
In this paper we derive holographic wave equations for hadrons with arbitrary spin starting from an effective action in a higher-dimensional space asymptotic to anti–de Sitter (AdS) space. Our procedure takes advantage of the local tangent frame, and it applies to all spins, including half-integer spins. An essential element is the mapping of the higher-dimensional equations of motion to the light-front Hamiltonian, thus allowing a clear distinction between the kinematical and dynamical aspects of the holographic approach to hadron physics. Accordingly, the nontrivial geometry of pure AdS space encodes the kinematics, and the additional deformations of AdS space encode the dynamics, including confinement. It thus becomes possible to identify the features of holographic QCD, which are independent of the specific mechanisms of conformal symmetry breaking. In particular, we account for some aspects of the striking similarities and differences observed in the systematics of the meson and baryon spectra.
DYNAMIC PROPERTIES OF AL-ALLOY FOAM BEAM DAMAGED BY COMPRESSIVE FATIGUE
Institute of Scientific and Technical Information of China (English)
Sung-Gaun Kim; Ilhyun Kim; Amkee Kim; Seung-Joon Kim; Junhong Park
2008-01-01
The permanent residual strain in aluminum (Al) alloy foams induced by compressive fatigue gradually increases with the increasing number of loading cycles.Consequently,the progressive shortening of Al-alloy foam degrades the dynamic material performance by the failure and ratcheting of multi-cells in the foam.In this paper,the dynamic properties of Al-alloy foams damaged by compressive fatigue were studied.The beam specimens with various residual strains were made by cyclic compression-compression stress.The dynamic bending modulus and loss factor were evaluated by using a beam transfer function method.As a result,the dynamic bending stiffness of Al-alloy foam turned out to be decreased due to damage while the loss factor was improved because of the increasing energy dissipation of such factors as cracked cell walls formed during the shortening process of the foam.The loss factor shows a manifest dependence on the fatigue residual strain.
Many-beam dynamical simulation of electron backscatter diffraction patterns
Energy Technology Data Exchange (ETDEWEB)
Winkelmann, Aimo [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany)], E-mail: winkelm@mpi-halle.mpg.de; Trager-Cowan, Carol; Sweeney, Francis [Department of Physics, University of Strathclyde, Glasgow G4 ONG, Scotland (United Kingdom); Day, Austin P. [Aunt Daisy Scientific Ltd., Dixton Rd., Monmouth, Gwent, NP25 3PP (United Kingdom); Parbrook, Peter [EPSRC National Centre for III-V Technologies, University of Sheffield (United Kingdom)
2007-04-15
We present an approach for the simulation of complete electron backscatter diffraction (EBSD) patterns where the relative intensity distributions in the patterns are accurately reproduced. The Bloch wave theory is applied to describe the electron diffraction process. For the simulation of experimental patterns with a large field of view, a large number of reflecting planes has to be taken into account. This is made possible by the Bethe perturbation of weak reflections. Very good agreement is obtained for simulated and experimental patterns of gallium nitride GaN{l_brace}0001{r_brace} at 20 kV electron energy. Experimental features like zone-axis fine structure and higher-order Laue zone rings are accurately reproduced. We discuss the influence of the diffraction of the incident beam in our experiment.
Many-beam dynamical simulation of electron backscatter diffraction patterns.
Winkelmann, Aimo; Trager-Cowan, Carol; Sweeney, Francis; Day, Austin P; Parbrook, Peter
2007-01-01
We present an approach for the simulation of complete electron backscatter diffraction (EBSD) patterns where the relative intensity distributions in the patterns are accurately reproduced. The Bloch wave theory is applied to describe the electron diffraction process. For the simulation of experimental patterns with a large field of view, a large number of reflecting planes has to be taken into account. This is made possible by the Bethe perturbation of weak reflections. Very good agreement is obtained for simulated and experimental patterns of gallium nitride GaN{0001} at 20kV electron energy. Experimental features like zone-axis fine structure and higher-order Laue zone rings are accurately reproduced. We discuss the influence of the diffraction of the incident beam in our experiment. PMID:17126489
International Nuclear Information System (INIS)
Using a new extraction line currently under construction, the ATF2 experiment plans to test the novel compact final focus optics design with local chromaticity correction intended for use in future linear colliders. With a 1.3 GeV design beam of 30nm normalized vertical emittance extracted from the ATF damping ring, the primary goal is to achieve a vertical spot-size at the IP waist of 37nm. We discuss our planned strategy for tuning the ATF2 beam to meet the primary goal. Simulation studies have been performed to asses the effectiveness of the strategy, including 'static' (installation) errors and dynamical effects (ground-motion, mechanical vibration, ring extraction jitter etc.). We have simulated all steps in the tuning procedure, from initial orbit establishment to final IP spot-size tuning. Through a Monte Carlo study of 100's of simulation seeds we find we can achieve a spot-size within ∼10% of the design optics value in at least 75% of cases. We also ran a simulation to study the long-term performance with the use of beam-based feedbacks
Analysis of the dynamic behavior of an intense charged particle beam using the semigroup approach
Stafford, M. A.
1985-05-01
Dynamic models of a charged particle beam subject to external electromagnetic fields are cast into the abstract Cauchy problem form. Various applications of intense charged particle beams, i.e., beams whose self electromagnetic fields are significant, might require, or be enhanced by, the use of dynamic control constructed from suitably processed measurements of the state of the beam. This research provides a mathematical foundation for future engineering development of estimation and control designs for such beams. Beginning with the Vlasov equation, successively simpler models of intense beams are presented, along with their corresponding assumptions. Expression of a model in abstract Cauchy problem form is useful in determining whether the model is well posed. Solutions of well-posed problems can be expressed in terms of a one-parameter semigroup of linear operators. (The state transition matrix for a system of linear, ordinary, first-order, constant coefficient differential equations is a special case of such a semigroup.) The semigroup point of view allows the application of the rapidly maturing modern control theory of infinite-dimensional systems. An appropriate underlying Banach space is identified for a simple, but non-trivial, single degree of freedom model (the electrostatic approximation model), and the associated one-parameter semigroup of linear operators is characterized.
Analysis of the dynamic behavior of an intense charged particle beam using the semigroup approach
International Nuclear Information System (INIS)
Dynamic models of a charged particle beam subject to external electromagnetic fields are cast into the abstract Cauchy problem form. Various applications of intense charged particle beams, i.e., beams whose self electromagnetic fields are significant, might require, or be enhanced by, the use of dynamic control constructed from suitably processed measurements of the state of the beam. This research provides a mathematical foundation for future engineering development of estimation and control designs for such beams. Beginning with the Vlasov equation, successively simpler models of intense beams are presented, along with their corresponding assumptions. Expression of a model in abstract Cauchy problem form is useful in determining whether the model is well posed. Solutions of well-posed problems can be expressed in terms of a one-parameter semigroup of linear operators. The semigroup point of view allows the application of the rapidly maturing modern control theory of infinite dimensional system. An appropriate underlying Banach space is identified for a simple, but nontrivial, single degree of freedom model (the electrostatic approximation model), and the associated one-parameter semigroup of linear operators is characterized
Beam dynamics in a rebunching CH cavity with high space charge
Energy Technology Data Exchange (ETDEWEB)
Schwarz, Malte; Heilmann, Manuel; Meusel, Oliver; Noll, Daniel; Podlech, Holger; Ratzinger, Ulrich; Seibel, Anja [Institute for Applied Physics, Goethe-University, Frankfurt am Main (Germany)
2013-07-01
The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is under construction with expected first beam in 2013. It will allow research on nucleosynthesis of elements in stars by the s-process as well as on neutron capture cross sections for activation experiments providing knowledge gain on transmutation of radioactive waste and fusion reactor materials. The 5-gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination and completes the LINAC section. It will be used for varying the output energy between 1.8 and 2.2 MeV as well as for focusing the proton beam bunch longitudinally to compensate the huge space charge forces at high currents up to 200 mA. Therefore beam dynamics and beam transport performance research on this CH cavity is under progress. It includes benchmarking of different beam dynamic codes like LORASR, TraceWin and a new particle-in-cell tracking code for non-relativistic beams currently under development at IAP as well as validation of the results by measurements. Furthermore, this CH rebuncher serves as prototype for CH cavity operation at MYRRHA (Mol, Belgium), an Accelerator Driven System (ADS) for transmutation of high level nuclear waste.
IH-DTL design with KONUS beam dynamics for KHIMA project
Lee, Yumi; Kim, Eun-San; Li, Zhihui; Hahn, Garam
2015-11-01
The Kombinierte Null Grad Struktur (KONUS) beam dynamics design of the interdigit H-mode drift tube linac (IH-DTL) for the Korea Heavy Ion Medical Accelerator (KHIMA) project is presented. We performed a KONUS beam dynamics simulation for a carbon beam (12C4+) with the LORASR code. The 12C4+ beam was accelerated from an input energy of 0.4 MeV/u to an output energy of 7 MeV/u by the IH-DTL operated at 200 MHz. The optimization aims were to increase the transmission efficiency and to minimize the beam emittance growth, beam loss, and project costs. The buncher with two gaps and two quadrupole doublets were placed between the RFQ and the IH-DTL. The whole IH-DTL consists of two tanks, 56 acceleration gaps, and four quadrupole triplets. It achieves a transmission efficiency of 100%. The total length from the exit of the RFQ to the exit of the IH-DTL is approximately 507.7 cm.
Nonlinear dynamics of a sliding beam on two supports under sinusoidal excitation
Indian Academy of Sciences (India)
R J Somnay; R A Ibrahim
2006-08-01
This study deals with the nonlinear dynamics associated with large deformation of a beam sliding on two-knife edge supports under external excitation. The beam is referred to as a Gospodnetic–Frisch-Fay beam, after the researchers who reported its static deformation in closed form. The freedom of the beam to slide on its supports imparts a nonlinear characteristic to the force-deﬂection response. The restoring elastic force of the beam possesses characteristics similar to those of the roll-restoring moment of ships. The Gospodnetic–Frisch-Fay exact solution is given in terms of elliptic functions. A curve ﬁt of the exact solution up to eleventh-order is constructed to establish the governing equation of motion under external excitation. The dynamic stability of the unperturbed beam is examined for the damped and undamped cases. The undamped case reveals periodic orbits and one homoclinic orbit depending on the value of the initial conditions. The response to a sinusoidal excitation at a frequency below the linear natural frequency is numerically estimated for different excitation amplitude and different values of initial conditions covered by the area of the homoclinic orbit. The safe basins of attraction are plotted for different values of excitation amplitude. It is found that the safe region of operation is reduced as the excitation amplitude increases.
Dynamic analysis and temperature measurements of concrete cantilever beam using fibre Bragg gratings
da Silva, Jean Carlos Cardozo; Martelli, Cicero; Kalinowski, Hypolito José; Penner, Elisabeth; Canning, John; Groothoff, Nathaniel
2007-01-01
We analyzed the action of fire, causing degradation in a concrete cantilever beam using dynamic testing. The structure was fitted with two fibre Bragg gratings (FBG) sensors. One of them measured vibration and the other measured the temperature inside of the cantilever beam, while the beam was exposed to fire. A high-temperature probe based on a simple packaging system, which isolates the sensing FBG from any mechanical action, was developed. A low-cost fibre Bragg grating interrogation system, including easy assembly and maintenance, was used for the measurements. The temperature in the cantilever beam increased until 150 °C and a reduction in the strength of concrete was observed through modal analysis. Results reveal a considerable reduction in strength occurs even with exposures to moderate temperatures (less than 90 °C).
Dynamics study of attaining heavy ion beam with a scale of nanosecond pulse length in CSR
International Nuclear Information System (INIS)
The feasibility of attaining short pulse duration heavy ion beam with a scale of nanosecond pulse length was studied in the Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring (HIRFL-CSR), such heavy ion beam can be produced by non-adiabatic compression, and it is implemented by a fast rotation in the longitudinal phase space. In this paper, the bunch compression beam dynamics of 238U72+ which the energy is 250 MeV/u, initial bunch pulse duration is 200 ns, and the initial momentum spread is 5 x 10-4 was computed with K-V envelope model, and the possible beam parameters are presented during bunch compression. The short 238U72+ bunch of 16 ns is got which can satisfy with the research of high energy density physics. (authors)
Dynamics of infrared multiphonon dissociation of SF6 by molecular beam method
International Nuclear Information System (INIS)
A crossed molecular beam apparatus has been adapted to study the dynamics of excitation and dissociation of polyatomic molecules in intense IR laser fields. Initial experiments have involved the study of the dissociation of SF6 by CO2 laser radiation at 10.6 μm. A molecular beam of SF6 was formed by supersonic expansion using three stages of differential pumping. A grating tuned pulsed CO2 TEA laser was used as the excitation source. The laser beam was focused by a 25 cm focal length ZnSe lens, and crossed the molecular beam near its focal point. The fragments produced by multiphonon dissociation of SF6 within the small interaction region were detected as a function of recoil angle and velocity. (Auth.)
Comprehensive proton dose algorithm using pencil beam redefinition and recursive dynamic splitting
Gottschalk, Bernard
2016-01-01
We compute, from first principles, the absolute dose or fluence distribution per incident proton charge in a known heterogeneous terrain exposed to known proton beams. The algorithm is equally amenable to scattered or scanned beams. All objects in the terrain (including collimators) are sliced into slabs, of any convenient thickness, perpendicular to the nominal beam direction. Transport is by standard Fermi-Eyges theory. Transverse heterogeneities are handled by breaking up pencil beams (PBs) either by conventional redefinition or a new form of 2D recursive dynamic splitting: the mother PB is replaced, conserving emittance and charge, by seven daughters of equal transverse size. One has 1/4 the charge and travels in the mother's direction and six have 1/8 the charge, are arranged hexagonally and radiate from the mother's virtual point source. The longitudinal (energy-like) variable is pv (proton momentum times speed). Each material encountered is treated on its own merits, not referenced to water. Slowing do...
NONLINEAR DYNAMICS OF AXIALLY ACCELERATING VISCOELASTIC BEAMS BASED ON DIFFERENTIAL QUADRATURE
Institute of Scientific and Technical Information of China (English)
Hu Ding; Liqun Chen
2009-01-01
This paper investigates nonlinear dynamical behaviors in transverse motion of an axially accelerating viscoelastic beam via the differential quadrature method. The governing equa-tion, a nonlinear partial-differential equation, is derived from the viscoelastic constitution relation using the material derivative. The differential quadrature scheme is developed to solve numeri-cally the governing equation. Based on the numerical solutions, the nonlinear dynamical behaviors presented in the case that the mean axial speed and the amplitude of the speed fluctuation are respectively varied while other parameters are fixed. The Lyapunov exponent and the initial value sensitivity of the different points of the beam, calculated from the time series based on the numer-ical solutions, are used to indicate periodic motions or chaotic motions occurring in the transverse motion of the axially accelerating viscoelastic beam.
Coherent and dynamic beam splitting based on light storage in cold atoms
Park, Kwang-Kyoon; Zhao, Tian-Ming; Lee, Jong-Chan; Chough, Young-Tak; Kim, Yoon-Ho
2016-01-01
We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the control lasers, it is possible to dynamically control the storage time, the power splitting ratio, the relative phase, and the optical frequencies of the output pulses. With further improvements, the active beam splitter demonstrated in this work might have applications in photonic photonic quantum information and in all-optical information processing. PMID:27677457
Simulation of high energy photoelectron diffraction using many-beam dynamical Kikuchi-band theory
Winkelmann, Aimo; Schröter, Bernd; Richter, Wolfgang
2004-06-01
We use the many-beam dynamical theory of electron diffraction for the calculation of x-ray photoelectron diffraction (XPD) patterns of the substrate emission. The reciprocity principle is used to apply a Bloch wave model for the diffraction of an incoming plane wave by a three-dimensional crystal. In this way, many-beam dynamical simulations of XPD in the context of Kikuchi-band theory can be carried out. This extends the results of the two-beam theory used so far and leads to quantitative descriptions of XPD patterns in the picture of photoelectrons reflected by lattice planes. The effects of forward scattering directions, substrate polarity, circular structures due to onedimensional diffraction, and emitter specific extinction of Kikuchi lines can be reproduced by Kikuchi-band theory. The results are compared with single scattering cluster calculations. In this way, the equivalence of the cluster approach and the Kikuchi-band picture can be demonstrated completely in both directions
Dynamics analysis of microsphere in a dual-beam fiber-optic trap with transverse offset.
Chen, Xinlin; Xiao, Guangzong; Luo, Hui; Xiong, Wei; Yang, Kaiyong
2016-04-01
A comprehensive dynamics analysis of microsphere has been presented in a dual-beam fiber-optic trap with transverse offset. As the offset distance between two counterpropagating beams increases, the motion type of the microsphere starts with capture, then spiral motion, then orbital rotation, and ends with escape. We analyze the transformation process and mechanism of the four motion types based on ray optics approximation. Dynamic simulations show that the existence of critical offset distances at which different motion types transform. The result is an important step toward explaining physical phenomena in a dual-beam fiber-optic trap with transverse offset, and is generally applicable to achieving controllable motions of microspheres in integrated systems, such as microfluidic systems and lab-on-a-chip systems. PMID:27137046
Static and dynamic stability of uniform shear beam-columns under generalized boundary conditions
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
Beam dynamics in the final focus section of the future linear collider
AUTHOR|(SzGeCERN)739431; TOMAS, Rogelio
The exploration of new physics in the ``Tera electron-Volt''~(TeV) scale with precision measurements requires lepton colliders providing high luminosities to obtain enough statistics for the particle interaction analysis. In order to achieve design luminosity values, linear colliders feature nanometer beam spot sizes at the Interaction~Point~(IP).\\par In addition to several effects affecting the luminosity, three main issues to achieve the beam size demagnification in the Final Focus Section (FFS) of the accelerator are the chromaticity correction, the synchrotron radiation effects and the correction of the lattice errors.\\par This thesis considers two important aspects for linear colliders: push the limits of linear colliders design, in particular the chromaticity correction and the radiation effects at 3~TeV, and the instrumentation and experimental work on beam stabilization in a test facility.\\par The current linear collider projects, CLIC~\\cite{CLICdes} and ILC~\\cite{ILCdes}, have lattices designed using...
Application of the Frequency Map Analysis to the Study of the Beam Dynamics of Light Sources
International Nuclear Information System (INIS)
The topic of this thesis is the study of beam dynamics in storage rings with a restriction to single particle transverse dynamics. In a first part, tools (Frequency Map Analysis, Hamiltonian, Integrator) are presented for studying and exploring the dynamics. Numerical simulations of four synchrotron radiation sources (the ALS, the ESRF, SOLEIL and Super-ACO) are performed. We construct a tracking code based on a new class of symplectic integrators (Laskar and Robutel, 2000). These integrators with only positive steps are more precise by an order of magnitude than the standard Forest and Ruth's scheme. Comparisons with the BETA, DESPOT and MAD codes are carried out. Frequency Map Analysis (Laskar, 1990) is our main analysis tool. This is a numerical method for analysing a conservative dynamical system. Based on a refined Fourier technique, it enables us to compute frequency maps which are real footprints of the beam dynamics of an accelerator. We stress the high sensitivity of the dynamics to magnetics errors and sextipolar strengths. The second part of this work is dedicated to the analysis of experimental results from two light sources. Together with the ALS accelerator team (Berkeley), we succeeded in obtaining the first experimental frequency map of an accelerator. The agreement with the machine model is very impressive. At the Super-ACO ring, the study of the tune shift with amplitude enabled us to highlight a strong octupolar-like component related to the quadrupole fringe field. The aftermaths for the beam dynamics are important and give us a better understanding the measured ring performance. All these results are based on turn by turn measurements. Many closely related phenomena are treated such as response matrix analysis or beam decoherence. (author)
Dynamically reconfigurable multiple beam illumination based on optical correlation
DEFF Research Database (Denmark)
Glückstad, Jesper; Palima, Darwin; Dam, Jeppe Seidelin;
2009-01-01
We adapt concepts from optical correlation and optical pattern recognition to propose a method for generating reconfigurable multiple spots with high efficiency. The generated spots correspond to the correlation spikes in optical pattern recognition. In pattern recognition, optimizing...... the correlation filter is constrained by the target pattern to be detected. The reverse process of light projection grants the freedom to optimize both the target pattern and the correlation filters. Combined with contemporary spatial light modulation technologies, the proposed method can yield dynamically...... reconfigurable optical patterns with high efficiency for optical micromanipulation and other applications....
Williams, J. H., Jr.; Lee, S. S.; Kousiounelos, P. N.
1981-01-01
An orthotropic double cantilever beam (DCB) model is used to study dynamic crack propagation and arrest in 90 deg unidirectional Hercules AS/3501-6 graphite fiber epoxy composites. The dynamic fracture toughness of the composite is determined from tests performed on the long-strip specimen and DCB crack arrest experiments are conducted. By using the dynamic fracture toughness in a finite-difference solution of the DCB governing partial differential equations, a numerical solution of the crack propagation and arrest events is computed. Excellent agreement between the experimental and numerical crack arrest results are obtained.
Energy harvesting by dynamic unstability and internal resonance for piezoelectric beam
International Nuclear Information System (INIS)
We investigated the energy harvesting of a vertical beam with tip mass under vertical excitations. We applied dynamic unstability and internal resonance to improve the efficiency of harvesting. The experiments of harmonic excitation were carried out. Results show that for the beam there exist internal resonances in the dynamically unstable and the buckling bistable cases. The dynamic unstability is a determinant for strong internal resonance or mode coupling, which can be used to create a large output from piezoelectric patches. Then, the experiments of stochastic excitation were carried out. Results prove that the internal resonance or mode coupling can transfer the excitation energy to the low order modes, mainly the first and the second one. This can bring about a large output voltage. For a stochastic excitation, it is proved that there is an optimal weight of tip mass for realizing internal resonance and producing large outputs
Web Cache Prefetching as an Aspect: Towards a Dynamic-Weaving Based Solution
DEFF Research Database (Denmark)
Segura-Devillechaise, Marc; Menaud, Jean-Marc; Muller, Gilles;
2003-01-01
Given the high proportion of HTTP traffic in the Internet, Web caches are crucial to reduce user access time, network latency, and bandwidth consumption. Prefetching in a Web cache can further enhance these benefits. For the best performance, however, the prefetching policy must match user and Web...... application characteristics. Thus, new prefetching policies must be loaded dynamically as needs change.Most Web caches are large C programs, and thus adding one or more prefetching policies to an existing Web cache is a daunting task. The main problem is that prefetching concerns crosscut the cache structure...... these issues. In particular, µ-Dyner provides a low overhead for aspect invocation, that meets the performance needs of Web caches....
Comparison of Parmela and MAFIA Simulations of Beam Dynamics in High Current Photoinjector
Kurennoy, Sergey S
2004-01-01
A high-current RF photoinjector producing low-emittance electron beam is an important technology for high-power CW FEL. LANL-AES team designed a 2.5-cell, pi-mode, 700-MHz normal-conducting RF photoinjector with magnetic emittance compensation. With the electric field gradients of 7, 7, and 5 MV/m in the three subsequent cells, the photoinjector will produce a 2.5-MeV electron beam with 3-nC charge per bunch and the transverse rms emittance 7 mm-mrad. Beam dynamics in the photoinjector has been modeled in details. In addition to the usual approach, with fields calculated by Superfish-Poisson and beam simulations performed by Parmela, we also used MAFIA group of codes, both to calculate cavity fields and to model beam dynamics with its particle-in-cell module TS. The second way naturally includes wake-field effects into consideration. The simulation results and comparison between two approaches will be presented.
Dynamic scattering of electron vortex beams – A Bloch wave analysis
Energy Technology Data Exchange (ETDEWEB)
Mendis, B.G., E-mail: b.g.mendis@durham.ac.uk
2015-02-15
Two important applications of electron vortex beams are in electron magnetic chiral dichroism (EMCD) measurements and nanoparticle manipulation. In both cases orbital angular momentum (
Dynamic scattering of electron vortex beams – A Bloch wave analysis
International Nuclear Information System (INIS)
Two important applications of electron vortex beams are in electron magnetic chiral dichroism (EMCD) measurements and nanoparticle manipulation. In both cases orbital angular momentum (
Nonlinear dynamics and chaos in an optomechanical beam
Navarro-Urrios, D; Colombano, M F; Garcia, P D; Sledzinska, M; Alzina, F; Griol, A; Martinez, A; Sotomayor-Torres, C M
2016-01-01
Optical non-linearities, such as thermo-optic effects and free-carrier-dispersion, are often considered as undesired effects in silicon-based resonators and, more specifically, optomechanical (OM) cavities, affecting the relative detuning between an optical resonance and the excitation laser. However, the interplay between such mechanisms could also enable unexpected physical phenomena to be used in new applications. In the present work, we exploit those non-linearities and their intercoupling with the mechanical degrees of freedom of a silicon OM nanobeam to unveil a rich set of fundamentally different complex dynamics. By smoothly changing the parameters of the excitation laser, namely its power and wavelength, we demonstrate accurate control for activating bi-dimensional and tetra-dimensional limit-cycles, a period doubling route and chaos. In addition, by scanning the laser parameters in opposite senses we demonstrate bistability and hysteresis between bi-dimensional and tetra-dimensional limit-cycles, be...
Dynamics of the echolocation beam during prey pursuit in aerial hawking bats.
Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie
2015-06-30
In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their "acoustic field of view." In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral "vision" than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation. PMID:26080398
Progress on optimization of the nonlinear beam dynamics in the MEIC collider rings
Energy Technology Data Exchange (ETDEWEB)
None, None
2015-07-13
One of the key design features of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is a small beta function at the interaction point (IP) allowing one to achieve a high luminosity of up to 10^{34} cm^{-2}s^{-1}. The required strong beam focusing unavoidably causes large chromatic effects such as chromatic tune spread and beam smear at the IP, which need to be compensated. This paper reports recent progress in our development of a chromaticity correction scheme for the ion ring including optimization of dynamic aperture and momentum acceptance.
Progress on Optimization of the Nonlinear Beam Dynamics in the MEIC Collider Rings
Energy Technology Data Exchange (ETDEWEB)
Morozov, Vasiliy S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Derbenev, Yaroslav S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Lin, Fanglei [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Pilat, Fulvia [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Zhang, Yuhong [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Cai, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Nosochkov, Y. M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Sullivan, Michael [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wang, M.-H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wienands, Uli [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-09-01
One of the key design features of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is a small beta function at the interaction point (IP) allowing one to achieve a high luminosity of up to 10^{34} cm^{-2}s^{-1}. The required strong beam focusing unavoidably causes large chromatic effects such as chromatic tune spread and beam smear at the IP, which need to be compensated. This paper reports recent progress in our development of a chromaticity correction scheme for the ion ring including optimization of dynamic aperture and momentum acceptance.
Dynamic structural analysis of the TPSG4 & TPSG6 beam diluters
Massidda, L; Kadi, Y; Balhan, B
2005-01-01
In this report we present the technical specification for the numerical model and the study of the dynamic structural behaviour of the beam diluter elements (TPSG4 & 6) protecting the extraction septum magnets (MSE & MST) in the event of an asynchronous firing of the extraction kickers (MKE). The deposited energy densities, estimated by the high-energy particle transport code FLUKA, were converted to internal heat generation rates according to the time dependence of the extracted beam. The transient response to this thermal load was obtained by solving the power deposition and structural deformation problem by the spectral-element code ELSE.
Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit
DEFF Research Database (Denmark)
Jakobsen, Lasse; Surlykke, Annemarie
2010-01-01
off-axis echoes. However, high directionality has context-specific disadvantages: at close range the detection space will be vastly reduced, making a broad beam favorable. Hence, a flexible system would be very advantageous. We investigated whether bats can dynamically change directionality......Animals using sound for communication emit directional signals, focusing most acoustic energy in one direction. Echolocating bats are listening for soft echoes from insects. Therefore, a directional biosonar sound beam greatly increases detection probability in the forward direction and decreases...
Beam dynamics design of the main accelerating section with KONUS in the CSR-LINAC
Xiao-Hu, Zhang; Jia-Wen, Xia; Xue-Jun, Yin; Heng, Du
2013-01-01
The CSR-LINAC injector has been proposed in Heavy Ion Research Facility in Lanzhou (HIRFL). The linac mainly consists of two parts, the RFQ and the IH-DTL. The KONUS (Kombinierte Null Grad Struktur) concept has been introduced into the DTL section. In this paper, the re-matching of the main accelerating section will be finished in the 3.7 MeV/u scheme and the new beam dynamics design up to 7 MeV/u will be also shown. Through the beam re-matching, the relative emittance growth has been suppressed greatly along the linac.
Effect of Beam Dynamics Processes in the Low Energy Ring ThomX
Delerue, N; Chaikovska, I; Drebot, I; Jacquet, M; Variola, A; Zomer, F; Loulergue, A
2014-01-01
As part of the R\\&D for the 50 MeV ThomX Compton source project, we have studied the effect of several beam dynamics processes on the evolution of the beam in the ring. The processes studied include among others Compton scattering, intrabeam scattering, coherent synchrotron radiation. We have performed extensive simulations of a full injection/extraction cycle (400000 turns). We show how each of these processes degrades the flux of photons produced and how a feedback system contributes to recovering most of the flux.
Directory of Open Access Journals (Sweden)
R. F. E. Guy
2009-01-01
Full Text Available Present mobile satellite communication systems use large antennas to provide multiple high-gain beams. Each beam covers a fixed geographic cell on the earth. Spatial frequency reuse is provided by synthesising beams with low-power levels over all cells operating at the same frequency. The performance needs for future systems are steadily increasing, leading to higher-gain requirements, which are met by using larger antennas with narrower beams. So the antenna pointing errors become a significant loss factor. An alternative approach is to abandon the use of fixed beams and dynamically synthesise the beams to optimise the antenna performance in real time. This both increases user gain and lowers cofrequency interference whilst also reducing the effects of pointing errors. Simulations, using the Inmarsat 4 antenna architecture as a test example, show that the spatial isolation performance can be significantly improved by using Dynamic Beam Synthesis.
ELASTIC-PLASTIC DYNAMIC RESPONSE OF A CANTILEVER BEAM SUBJECTED TO OBLIQUE IMPACT AT ITS TIP
Institute of Scientific and Technical Information of China (English)
Xi Feng; Liu Feng
2005-01-01
By employing large deformation governing equations expressed in the form of finite difference, the dynamic responses of an elastic, perfectly plastic cantilever subjected to an oblique impact at its tip was numerically studied. Through analyzing the instantaneous distribution of the yield function (ψ= |M/Mo|+ (N/No)2), bending moment and axial force during the early stage of the response, the elastic-plastic deformation mechanism and the influence of axial component of an oblique impact on the dynamic response of a cantilever beam were discussed. The present analysis shows that the deformation mechanism of an elastic-plastic cantilever subjected to an obtained by using the rigid, perfectly plastic approach, the mode of shrinking plastic region that occurred instantly after the oblique impact and the mode of stationary hinge were both confirmed.The primary features of the deformation mechanism are captured by both analysis methods. It has also been found that the beam's deformation is mainly controlled by the axial component of the oblique impact in the early phase of the dynamic response, the deformation mechanism is obviously different from the case of a transverse impact. With further development of the response,the axial component attenuates rapidly and gives negligible contribution to the yielding of the beam cross-section. At the same time, the bending moments along the cantilever develop gradually and dominate the beam's deformation. The numerical results indicate that the mass, impact speed and oblique angle are the important factors that influence the elastic-plastic dynamic response of a cantilever beam.
Face processing regions are sensitive to distinct aspects of temporal sequence in facial dynamics.
Reinl, Maren; Bartels, Andreas
2014-11-15
Facial movement conveys important information for social interactions, yet its neural processing is poorly understood. Computational models propose that shape- and temporal sequence sensitive mechanisms interact in processing dynamic faces. While face processing regions are known to respond to facial movement, their sensitivity to particular temporal sequences has barely been studied. Here we used fMRI to examine the sensitivity of human face-processing regions to two aspects of directionality in facial movement trajectories. We presented genuine movie recordings of increasing and decreasing fear expressions, each of which were played in natural or reversed frame order. This two-by-two factorial design matched low-level visual properties, static content and motion energy within each factor, emotion-direction (increasing or decreasing emotion) and timeline (natural versus artificial). The results showed sensitivity for emotion-direction in FFA, which was timeline-dependent as it only occurred within the natural frame order, and sensitivity to timeline in the STS, which was emotion-direction-dependent as it only occurred for decreased fear. The occipital face area (OFA) was sensitive to the factor timeline. These findings reveal interacting temporal sequence sensitive mechanisms that are responsive to both ecological meaning and to prototypical unfolding of facial dynamics. These mechanisms are temporally directional, provide socially relevant information regarding emotional state or naturalness of behavior, and agree with predictions from modeling and predictive coding theory. PMID:25132020
Statistical signal processing techniques for coherent transversal beam dynamics in synchrotrons
Energy Technology Data Exchange (ETDEWEB)
Alhumaidi, Mouhammad
2015-03-04
identifying and analyzing the betatron oscillation sourced from the kick based on its mixing and temporal patterns. The accelerator magnets can generate unwanted spurious linear and non-linear fields due to fabrication errors or aging. These error fields in the magnets can excite undesired resonances leading together with the space charge tune spread to long term beam losses and reducing dynamic aperture. Therefore, the knowledge of the linear and non-linear magnets errors in circular accelerator optics is very crucial for controlling and compensating resonances and their consequent beam losses and beam quality deterioration. This is indispensable, especially for high beam intensity machines. Fortunately, the relationship between the beam offset oscillation signals recorded at the BPMs is a manifestation of the accelerator optics, and can therefore be exploited in the determination of the optics linear and non-linear components. Thus, beam transversal oscillations can be excited deliberately for purposes of diagnostics operation of particle accelerators. In this thesis, we propose a novel method for detecting and estimating the optics lattice non-linear components located in-between the locations of two BPMs by analyzing the beam offset oscillation signals of a BPMs-triple containing these two BPMs. Depending on the non-linear components in-between the locations of the BPMs-triple, the relationship between the beam offsets follows a multivariate polynomial accordingly. After calculating the covariance matrix of the polynomial terms, the Generalized Total Least Squares method is used to find the model parameters, and thus the non-linear components. A bootstrap technique is used to detect the existing polynomial model orders by means of multiple hypothesis testing, and determine confidence intervals for the model parameters.
A study of some aspects of gas-slag-metal interactions : Towards dynamic process model and control
Ek, Mattias
2012-01-01
The present thesis deals with the development of a new type of dynamic model for metallurgical reactors. It also covers some of the theoretical aspects of steelmaking that is necessary to include in such an application. The thesis consists of modeling work, high temperature experiments and cold model experiments. Two different aspects of slags in the oxygen steelmaking were investigated. In the first study, slag samples were equilibrated with copper at 1923K in order to study their capacities...
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Based on the electron dynamic diffraction, phase shift of the exit wave function vs misorientation of the incident electron beam from the exact zone axis has been calculated for the [001] oriented copper. The result shows that the peak of phase shift is the maximum at the atom position as the electron beam along the exact [001] zone axis, and the peak value of phase shift decreases as increases of the misorientation. At small misorientation, i.e. less than 5 degree, change of the phase shift is minimal. The peak value of phase shift decreases significantly when the incident beam deviates form the zone axis over 10 degree and the exit wave has a planar configuration as the misoriention angle arrives ～17 degree. The effect of this phase shift characteristics on the information extracted from the hologram has also been considered.
Dynamic CCT Diagram of Automobile Beam Steel With High Strength Produced by FTSR Technology
Institute of Scientific and Technical Information of China (English)
WANG Xin; KANG Yong-lin; YU Hao; CHEN Li-bin; KONG Qing-fu
2008-01-01
The dynamic continuous cooling transformation (CCT) diagram and phase transformation rules of 510 MPa automobile beam steel, which is produced by a continuous casting of thin slab of FTSR technology in Tangshan Iron and Steel Co. Ltd. , are researched by thermal simulation experiment. The mierostructure characteristics of the beam steel under different test conditions are studied by means of optical microscope and scanning electron microscope. The test results show that the critical temperatures of phase transformation Ar3 and Ar1 will all decrease with the increase of the cooling rate. When the cooling rate is lower than 20℃·s-1, the ferrite and pearlite phase transformations are the main parts; when the cooling rate is higher than 20℃· s-1, the bainite phase appears. Moreover, the microstructurea of 510 MPa automobile beam steel produced by FTSR technology are also studied, and the results are basically in accordance with the CCT diagram gained from the test.
Dynamics of Finite Energy Airy Beams Carrying Orbital Angular Momentum in Multilevel Atomic Vapors
Wu, Zhenkun; Wang, Shun; Hu, Weifei; Gu, Yuzong
2016-10-01
We numerically investigate the dynamics of inward circular finite-energy Airy beams carrying different orbital angular momentum (OAM) numbers in a close-Λ three-level atomic vapor with the electromagnetically induced transparency (EIT) window. We report that due to the EIT induced by the microwave field, the transverse intensity distribution properties of Airy beam can be feasibly manipulated and modulated through adjusting OAM numbers l and the frequency detuning, as well as the propagation distance, in the multi-level atomic systems. What's more, the rotation of the beam also can be observed with different positions in atomic ensembles. The investigation may provide a useful tool for studying particle manipulation, signal processing and propagation in graded-index (GRIN) fibers.
BEAM DYNAMICS FOR A PHOTOINJECTED ENERGY RECOVERY LINAC AT THE NSLS.
Energy Technology Data Exchange (ETDEWEB)
MURPHY,J.B.; BEN-ZVI,I.; TOWNE,N.; WANG,J.M.; WANG,X.J.; WU,J.H.; YAKIMENKO,V.
2001-06-18
The Photoinjected Energy Recovery Linac (PERL) design study at the NSLS is considering the feasibility of a new synchrotron light source based on a 3-7 GeV energy recovering superconducting linac initiated by a photo-injected RF gun [1]. To be a competitive light source the photoinjector must provide high brightness electron beams with a normalized transverse emittance of 0.5-1 mm-mrad and a bunch charge per of 0.15-0.45 nC at a rep rate of 0.43-1.3 GHz. We provide a first pass assessment of some of the beam dynamics issues that are critical to preserving the high brightness beams.
Slip-stacking Dynamics for High-Power Proton Beams at Fermilab
International Nuclear Information System (INIS)
Slip-stacking is a particle accelerator configuration used to store two particle beams with different momenta in the same ring. The two beams are longitudinally focused by two radiofrequency (RF) cavities with a small frequency difference between them. Each beam is synchronized to one RF cavity and perturbed by the other RF cavity. Fermilab uses slip-stacking in the Recycler so as to double the power of the 120 GeV proton beam in the Main Injector. This dissertation investigates the dynamics of slip-stacking beams analytically, numerically and experimentally. In the analytic analysis, I find the general trajectory of stable slip-stacking particles and identify the slip-stacking parametric resonances. In the numerical analysis, I characterize the stable phase-space area and model the particle losses. In particular, I evaluate the impact of upgrading the Fermilab Booster cycle-rate from 15 Hz to 20 Hz as part of the Proton Improvement Plan II (PIP-II). The experimental analysis is used to verify my approach to simulating slip-stacking loss. I design a study for measuring losses from the longitudinal single-particle dynamics of slip-stacking as a function of RF cavity voltage and RF frequency separation. I further propose the installation of a harmonic RF cavity and study the dynamics of this novel slip-stacking configuration. I show the harmonic RF cavity cancels out parametric resonances in slip-stacking, reduces emittance growth during slip-stacking, and dramatically enhances the stable phase-space area. The harmonic cavity is expected to reduce slip-stacking losses to far exceed PIP-II requirements. These results raise the possibility of extending slip-stacking beyond the PIP-II era.
Slip-stacking Dynamics for High-Power Proton Beams at Fermilab
Energy Technology Data Exchange (ETDEWEB)
Eldred, Jeffrey Scott [Indiana Univ., Bloomington, IN (United States)
2015-12-01
Slip-stacking is a particle accelerator configuration used to store two particle beams with different momenta in the same ring. The two beams are longitudinally focused by two radiofrequency (RF) cavities with a small frequency difference between them. Each beam is synchronized to one RF cavity and perturbed by the other RF cavity. Fermilab uses slip-stacking in the Recycler so as to double the power of the 120 GeV proton beam in the Main Injector. This dissertation investigates the dynamics of slip-stacking beams analytically, numerically and experimentally. In the analytic analysis, I find the general trajectory of stable slip-stacking particles and identify the slip-stacking parametric resonances. In the numerical analysis, I characterize the stable phase-space area and model the particle losses. In particular, I evaluate the impact of upgrading the Fermilab Booster cycle-rate from 15 Hz to 20 Hz as part of the Proton Improvement Plan II (PIP-II). The experimental analysis is used to verify my approach to simulating slip-stacking loss. I design a study for measuring losses from the longitudinal single-particle dynamics of slip-stacking as a function of RF cavity voltage and RF frequency separation. I further propose the installation of a harmonic RF cavity and study the dynamics of this novel slip-stacking configuration. I show the harmonic RF cavity cancels out parametric resonances in slip-stacking, reduces emittance growth during slip-stacking, and dramatically enhances the stable phase-space area. The harmonic cavity is expected to reduce slip-stacking losses to far exceed PIP-II requirements. These results raise the possibility of extending slip-stacking beyond the PIP-II era.
Dynamic stiffness matrix of thin-walled composite I-beam with symmetric and arbitrary laminations
Kim, Nam-Il; Shin, Dong Ku; Park, Young-Suk
2008-11-01
For the spatially coupled free vibration analysis of thin-walled composite I-beam with symmetric and arbitrary laminations, the exact dynamic stiffness matrix based on the solution of the simultaneous ordinary differential equations is presented. For this, a general theory for the vibration analysis of composite beam with arbitrary lamination including the restrained warping torsion is developed by introducing Vlasov's assumption. Next, the equations of motion and force-displacement relationships are derived from the energy principle and the first order of transformed simultaneous differential equations are constructed by using the displacement state vector consisting of 14 displacement parameters. Then explicit expressions for displacement parameters are derived and the exact dynamic stiffness matrix is determined using force-displacement relationships. In addition, the finite-element (FE) procedure based on Hermitian interpolation polynomials is developed. To verify the validity and the accuracy of this study, the numerical solutions are presented and compared with analytical solutions, the results from available references and the FE analysis using the thin-walled Hermitian beam elements. Particular emphasis is given in showing the phenomenon of vibrational mode change, the effects of increase of the modulus and the bending-twisting coupling stiffness for beams with various boundary conditions.
High current beam transport with multiple beam arrays
International Nuclear Information System (INIS)
Highlights of recent experimental and theoretical research progress on the high current beam transport of single and multiple beams by the Heavy Ion Fusion Accelerator Research (HIFAR) group at the Lawrence Berkeley Laboratory (LBL) are presented. In the single beam transport experiment (SBTE), stability boundaries and the emittance growth of a space charge dominated beam in a long quadrupole transport channel were measured and compared with theory and computer simulations. Also, a multiple beam ion induction linac (MBE-4) is being constructed at LBL which will permit study of multiple beam transport arrays, and acceleration and bunch length compression of individually focused beamlets. Various design considerations of MBE-4 regarding scaling laws, nonlinear effects, misalignments, and transverse and longitudinal space charge effects are summarized. Some aspects of longitudinal beam dynamics including schemes to generate the accelerating voltage waveforms and to amplify beam current are also discussed
Kartashov, Yaroslav V; Konotop, Vladimir V; Torner, Lluis
2016-01-01
We address the propagation of light beams in longitudinally modulated PT-symmetric lattices, built as arrays of couplers with periodically varying separation between their channels, and show a number of possibilities for efficient diffraction control available in such non-conservative structures. The dynamics of light in such lattices crucially depends on the ratio of the switching length for the straight segments of each coupler and the longitudinal lattice period. Depending on the longitudinal period, one can achieve either beam rectification, when the input light propagates at a fixed angle across the structure without diffractive broadening, or dynamic localization, when the initial intensity distribution is periodically restored after each longitudinal period. Importantly, the transition between these two different propagation regimes can be achieved by tuning only gain and losses acting in the system, provided that the PT-symmetry remains unbroken. The impact of Kerr nonlinearity is also discussed.
Object-Oriented Parallel Particle-in-Cell Code for Beam Dynamics Simulation in Linear Accelerators
Energy Technology Data Exchange (ETDEWEB)
Qiang, J.; Ryne, R.D.; Habib, S.; Decky, V.
1999-11-13
In this paper, we present an object-oriented three-dimensional parallel particle-in-cell code for beam dynamics simulation in linear accelerators. A two-dimensional parallel domain decomposition approach is employed within a message passing programming paradigm along with a dynamic load balancing. Implementing object-oriented software design provides the code with better maintainability, reusability, and extensibility compared with conventional structure based code. This also helps to encapsulate the details of communications syntax. Performance tests on SGI/Cray T3E-900 and SGI Origin 2000 machines show good scalability of the object-oriented code. Some important features of this code also include employing symplectic integration with linear maps of external focusing elements and using z as the independent variable, typical in accelerators. A successful application was done to simulate beam transport through three superconducting sections in the APT linac design.
High performance computation on beam dynamics problems in high intensity compact cyclotrons
Institute of Scientific and Technical Information of China (English)
ADELMANN; Andreas
2011-01-01
This paper presents the research progress in the beam dynamics problems for future high intensity compact cyclotrons by utilizing the state-of-the-art high performance computation technology. A "Start-to-Stop" model, which includes both the interaction of the internal particles of a single bunch and the mutual interaction of neighboring multiple bunches in the radial direction, is established for compact cyclotrons with multi-turn extraction. This model is then implemented in OPAL-CYCL, which is a 3D object-oriented parallel code for large scale particle simulations in cyclotrons. In addition, to meet the running requirement of parallel computation, we have constructed a small scale HPC cluster system and tested its performance. Finally, the high intensity beam dynamics problems in the 100 MeV compact cyclotron, which is being constructed at CIAE, are studied using this code and some conclusions are drawn.
Li, L.; Zhang, D. G.; Zhu, W. D.
2014-02-01
A comprehensive dynamic model of a rotating hub-functionally graded material (FGM) beam system is developed based on a rigid-flexible coupled dynamics theory to study its free vibration characteristics. The rigid-flexible coupled dynamic equations of the system are derived using the method of assumed modes and Lagrange's equations of the second kind. The dynamic stiffening effect of the rotating hub-FGM beam system is captured by a second-order coupling term that represents longitudinal shrinking of the beam caused by the transverse displacement. The natural frequencies and mode shapes of the system with the chordwise bending and stretching (B-S) coupling effect are calculated and compared with those with the coupling effect neglected. When the B-S coupling effect is included, interesting frequency veering and mode shift phenomena are observed. A two-mode model is introduced to accurately predict the most obvious frequency veering behavior between two adjacent modes associated with a chordwise bending and a stretching mode. The critical veering angular velocities of the FGM beam that are analytically determined from the two-mode model are in excellent agreement with those from the comprehensive dynamic model. The effects of material inhomogeneity and graded properties of FGM beams on their dynamic characteristics are investigated. The comprehensive dynamic model developed here can be used in graded material design of FGM beams for achieving specified dynamic characteristics.
Dynamic stability of parametrically-excited linear resonant beams under periodic axial force
Institute of Scientific and Technical Information of China (English)
Li Jing; Fan Shang-Chun; Li Yan; Guo Zhan-She
2012-01-01
The parametric dynamic stability of resonant beams with various parameters under periodic axial force is studied.It is assumed that the theoretical formulations are based on Euler Bernoulli beam theory.The governing equationsof motion are derived by using the Rayleigh Ritz method and transformed into Mathieu equations,which are formedto determine the stability criterion and stability regions for parametricallyexcited linear resonant beams.An improved stability criterion is obtained using periodic Lyapunov functions.The boundary points on the stable regions are determined by using a small parameter perturbation method.Numerical results and discussion are presented to highlight the effects of beam length,axial force and damped coefficient on the stability criterion and stability regions.While some stability rules are easy to anticipate,we draw some conclusions: with the increase of damped coefficient,stable regions arise;with the decrease of beam length,the conditions of the damped coefficient arise instead.These conclusions can provide a reference for the robust design of parametricallyexcited linear resonant sensors.
Modeling of explosive electron emission and electron beam dynamics in high-current devices
International Nuclear Information System (INIS)
Based on a detailed analysis of explosive electron emission in high-current electronic devices, we formulate a system of equations that describes the expansion of the cathode plasma and the generation of high-current electron beams. The system underlies the numerical algorithm for the hybrid code which enables simulating the charged particles' dynamics in high-current vircators with open resonators. Using the Gabor-Morlet transform, we perform the time-frequency analysis of vircator radiation
Institute of Scientific and Technical Information of China (English)
WANG SHU-FENG; QIN YUAN-DONG; YANG HONG; WANG DAN-LING; ZHU CHANG-JUN; GONG QI-HUANG
2001-01-01
The dynamic process of white-continuum generation in water was investigated by the pump-probe technique with a femtosecond intense laser at 805nm. The spectrum width of the probe beam was broadened at the blue side and varied with different delay times. This blueshift was attributed to the ionization-enhanced optical nonlinearity, in which both the multi-photon ionization and avalanche ionization had an effect.
Carrier dynamics in ZnxCd1-xO films grown by molecular beam epitaxy
Cheng, F. J.; Lee, Y. C.; Hu, S. Y.; Lin, Y. C.; Tiong, K. K.; Chou, W. C.
2016-05-01
In this work, the carrier dynamics in Zn1-xCdxO thin films with different Cd contents grown by molecular beam epitaxy system have been investigated using photoluminescence and time-resolved photoluminescence measurements. The carrier lifetime can be estimated from the PL decay curve fitted by triple exponential function. The emission energy dependence and temperature dependence of the PL decay time indicate that carrier localization dominate the luminescence mechanism of the ZnCdO alloy semiconductor.
Modeling of explosive electron emission and electron beam dynamics in high-current devices
Anishchenko, S. V.; Gurinovich, A. A.
2014-03-01
Based on a detailed analysis of explosive electron emission in high-current electronic devices, we formulate a system of equations that describes the expansion of the cathode plasma and the generation of high-current electron beams. The system underlies the numerical algorithm for the hybrid code which enables simulating the charged particles' dynamics in high-current vircators with open resonators. Using the Gabor-Morlet transform, we perform the time-frequency analysis of vircator radiation.
Nonlinear Accelerator Problems via Wavelets; 3, Effects of Insertion Devices on Beam Dynamics
Fedorova, A N; Fedorova, Antonina N.; Zeitlin, Michael G.
1999-01-01
In this series of eight papers we present the applications of methods from wavelet analysis to polynomial approximations for a number of accelerator physics problems. In this part, assuming a sinusoidal field variation, we consider the analytical treatment of the effects of insertion devices on beam dynamics. We investigate via wavelet approach a dynamical model which has polynomial nonlinearities and variable coefficients. We construct the corresponding wavelet representation. As examples we consider wigglers and undulator magnets. We consider the further modification of our variational approach which may be applied in each scale.
Institute of Scientific and Technical Information of China (English)
LIU Shi-Bing; CHEN Tao; CHEN Shi-Gang
2004-01-01
An essential dispersion relation,which can describe the dynamic properties of stimulated Raman scattering instability as a laser beam propagates through plasmas,is derived analytically.The development of growth mode,angle distribution,and temperature dependence of the instabilities are presented by solving this dispersion relation numerically.A significant dynamic characteristic has been revealed that the temperature increasing of the electron would result in redshift of scattered spectrum at high laser intensities.Furthermore,a novel modulational instability with double-peak temporal structure appears in a limited density region because of the coupling of scattered upshift and downshift waves.
Institute of Scientific and Technical Information of China (English)
Xiao-Ting Rui; Edwin Kreuzer; Bao Rong; Bin He
2012-01-01
In this paper,by defining new state vectors and developing new transfer matrices of various elements moving in space,the discrete time transfer matrix method of multi-rigid-flexible-body system is expanded to study the dynamics of muhibody system with flexible beams moving in space.Formulations and numerical example of a rigidflexible-body three pendulums system moving in space are given to validate the method. Using the new method to study the dynamics of multi-rigid-flexible-body system mov ing in space,the global dynamics equations of system are not needed,the orders of involved matrices of the system are very low and the computational speed is high,irrespective of the size of the system.The new method is simple,straightforward,practical,and provides a powerful tool for multi-rigid-flexible-body system dynamics.
Rui, Xiao-Ting; Kreuzer, Edwin; Rong, Bao; He, Bin
2012-04-01
In this paper, by defining new state vectors and developing new transfer matrices of various elements moving in space, the discrete time transfer matrix method of multi-rigid-flexible-body system is expanded to study the dynamics of multibody system with flexible beams moving in space. Formulations and numerical example of a rigid-flexible-body three pendulums system moving in space are given to validate the method. Using the new method to study the dynamics of multi-rigid-flexible-body system moving in space, the global dynamics equations of system are not needed, the orders of involved matrices of the system are very low and the computational speed is high, irrespective of the size of the system. The new method is simple, straightforward, practical, and provides a powerful tool for multi-rigid-flexible-body system dynamics.
Vieira, Tárcio A; Zamboni-Rached, Michel; Recami, Erasmo
2015-01-01
In recent times, we experimentally realized a quite efficient modeling of the shape of diffraction-resistant optical beams; thus generating for the first time the so-called Frozen Waves (FW), whose longitudinal intensity pattern can be arbitrarily chosen, within a prefixed space interval of the propagation axis. Such waves possess a host of potential applications: in medicine, biomedical optics, optical tweezers, atom guiding, remote sensing, tractor beams, optical communications or metrology, and other topics in photonic areas. In this work, we extend our theory of FWs -- which led to beams endowed with a static envelope -- through a dynamic modeling of the FWs, whose shape is now allowed to evolve in time in a predetermined way. And we experimentally create such dynamic FWs in Optics, via a computational holographic technique and a spatial light modulator. Experimental results are here presented for two cases of dynamic FWs, one of the zeroth and the other of higher order, the last one being the most intere...
Radiation defect dynamics in Si at room temperature studied by pulsed ion beams
Energy Technology Data Exchange (ETDEWEB)
Wallace, J. B.; Myers, M. T. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA and Department of Nuclear Engineering, Texas A& M University, College Station, Texas 77843 (United States); Charnvanichborikarn, S.; Bayu Aji, L. B.; Kucheyev, S. O. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Shao, L. [Department of Nuclear Engineering, Texas A& M University, College Station, Texas 77843 (United States)
2015-10-07
The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length is revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ∼4–13 ms and a diffusion length of ∼15–50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.
Dynamic analysis of smart composite beams by using the frequency domain spectral element method
Energy Technology Data Exchange (ETDEWEB)
Park, Il Wook; Lee, Usik [Inha Univ., Incheon (Korea, Republic of)
2012-08-15
To excite or measure the dynamic responses of a laminated composite structure for the active controls of vibrations or noises, wafertype piezoelectric transducers are often bonded on the surface of the composite structure to form a multi layer smart composite structure. Thus, for such smart composite structures, it is very important to develop and use a very reliable mathematical and/or computational model for predicting accurate dynamic characteristics. In this paper, the axial-bending coupled equations of motion and boundary conditions are derived for two layer smart composite beams by using the Hamilton's principle with Lagrange multipliers. The spectral element model is then formulated in the frequency domain by using the variation approach. Through some numerical examples, the extremely high accuracy of the present spectral element model is verified by comparing with the solutions by the conventional finite element model provided in this paper. The effects of the lay up of composite laminates and surface bonded wafer type piezoelectric (PZT) layer on the dynamics and wave characteristics of smart composite beams are investigated. The effective constraint forces at the interface between the base beam and PZT layer are also investigated via Lagrange multipliers.
The effect of insertion devices on the beam dynamics in PLS-II
Energy Technology Data Exchange (ETDEWEB)
Chunjarean, S.; Kim, D. E.; Shin, S. [Pohang University of Science and Technology, Pohang (Korea, Republic of)
2014-05-15
The effects of an insertion device (ID) on the beam dynamics of the PLS-II storage ring have been investigated quantitatively. Although the linear perturbations caused by high field wigglers, such as tune shift and beta-beating, are corrected by using iterative Twiss-matching, particles may be unstable in the transverse planes due to nonlinear ID fields. Intrinsic non-linear fields and transverse magnetic field roll off cause ID field-perturbations making the beam unstable and possibly causing a reduction in the injection efficiency and the beam's lifetime. Therefore, a frequency map analysis is used to analyze the transverse dynamics with high field IDs. In order to analyze the transverse dynamics by using frequency map analysis, we model a three dimensional magnetic field based on numerical data with a Taylor expansion to accurately represent the actual field. As a result, new operation tunes, 15.245 and 9.18, are suggested rather than the designed tunes of 15.28 and 9.18. The new tunes are used for Twiss-matching and require several iterations to reduce both the horizontal and the vertical beta beatings. In this paper, the effects of an insertion device and their compensations will be presented.
THE STATIC AND DYNAMIC ASPECTS OF ROMAN LAW AS PORTRAYED IN THE SOURCES OF LAW
Directory of Open Access Journals (Sweden)
Alina Monica AXENTE
2015-07-01
Full Text Available The dynamics of the private Roman law sources had been influenced by the conjoined action of three factors: the Romans’ conservative mentality, their practicality and the incorporation of the concepts of equity and good faith into their legal system. By virtue of the Romans’ conservative mentality, their private law functioned according to less than thirty laws. Towards the end of the Republic, against the background of the economic revolution that gave variety to social relations and enhanced their complexity, many of the provisions of the old laws, including those laid down under the Law of the Twelve Tables, became inapplicable. Faced with these challenges and animated by their practicality, the Romans realized that appropriate measures had to be taken so as to strike a balance between the provisions of the law and the new demands of the ever-changing Roman social life. To this end, they started from the conviction that trade economy could not be strengthened and further develop without an effective legal ordinance. In order to counterbalance the discrepancy between the laws and the development of the social environment, the Romans resorted to procedural means and extensive research upon which they elaborated in accordance with the principles of equity and good faith. Consequently, towards the end of the Republic, the Praetor’s Edict and the jurisprudence functioned as a legal filter with a view to striking a balance between the provisions of the old laws and the new social atmosphere. Throughout this stage in the evolution of private Roman law sources, the law embodied the static aspect, whereas the Praetor’s Edict represented its dynamic counterpart. Therefore, by means of interweaving tradition with innovation, the Romans managed to modernize the private law under the impression that the old laws were still in effect.
Directory of Open Access Journals (Sweden)
Argyris Arnellos
2005-02-01
Full Text Available Initially, the analysis and development of adaptive artificial systems has been based in metaphors taken from philosophical schools as well as the disciplines of biology and cognitive science. So far, the dominant approaches exhibit many advantages in specific domains of application but there all have a certain drawback, which is their inability to produce an artificial system which will be able to internally ground its representations so as to use them to produce newer, more developed ones. The respective frameworks are studied in terms of this inability and it is concluded that the problem is traced in the purely causal treatment, function and creation of the notion of representation, wherever it is used. In the case of purely dynamic systems, where the representations seem not to be very useful, it is proposed that the incorporation of a special non-causal kind of representations would give a framework which seems promising in realizing real adaptation. The relevant architecture is analyzed and discussed mainly in terms of its functionality and its contribution to the integration of pragmatic meaning aspects in an artificial system's interaction.
Lee, Jinkyo
1993-01-01
Efficient and accurate analytical or semi-analytical solutions have been developed for the dynamics of one and two dimensional linear structures employing elemental dynamic flexibility formulation. This dissertation is divided into three parts. In the first, the elemental flexibility formulation is developed for Euler-Bernoulli beams having discontinuous section properties, which can be viewed as the synthesis of uniform beams, and the exactness of the solution is established. In the second, the elemental flexibility formulation is extended to thin rectangular plates having Levy boundary conditions, and conditions under which the exact solution can be achieved are presented. In the third, the structural-acoustic problem of Helmholtz fluid enclosed by a partially flexible cavity is posed and solved. Here, a concise analytical representation of the structural dynamics is used in conjunction with a boundary element approach for the fluid medium to give an efficient and accurate semi-analytical solution. All three sections are organized along similar lines. Following an introduction and review of the pertinent literature, the governing equations are derived and solved, a series of example problems is presented, the results from the examples are compared with similar results from the literature, and efficacy of the method when compared with other methods is discussed. This is followed by a general conclusions section and a series of appendices.
Incoherent beam-beam effect---The relationship between tune-shift, bunch length and dynamic aperture
International Nuclear Information System (INIS)
Simulation studies of the influence of long bunches on the beam-beam effect in particle colliders suggest that, despite the risk from synchro-betatron resonances, the attainable luminosity may be greater than that obtained for short bunches
Medina, Lior; Gilat, Rivka; Krylov, Slava
2016-07-01
In this work, the results of numerical investigations of the transient dynamics of a stress-free initially curved bistable double clamped micro beam actuated by a suddenly applied electrostatic force are presented. The analysis is based on a reduced order (RO) model derived through the Galerkin decomposition. Two beam configurations and two corresponding loading scenarios are considered. In the first case, the beam, which manifests two stable equilibria both accessible under quasi-static loading, is subjected to a suddenly applied (step function) voltage. Under such a signal, the beam may snap into the second stable configuration or bounce back to its initial position. We map the regions of the various types of response on the actuation voltage - quality factor plane. In the second case, the configuration of the beam is such that the second equilibrium is inaccessible neither under quasi static loading nor under a suddenly applied load. However, it is attainable by means of a specially tailored dynamic actuation, for example, by a two step voltage signal that is considered here. For this case, we map the conditions allowing the trapping of the beam in the second stable state, depending on the properties of the signal and the level of damping. We also demonstrate that trapping the dynamically bistable beam at a stable state located in the close proximity to the electrode may result in much more efficient gap usage than in the case of statically bistable beam or of an initially straight beam.
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.
Downer, Janice Diane
1990-01-01
The dynamic analysis of three dimensional elastic beams which experience large rotational and large deformational motions are examined. The beam motion is modeled using an inertial reference for the translational displacements and a body-fixed reference for the rotational quantities. Finite strain rod theories are then defined in conjunction with the beam kinematic description which accounts for the effects of stretching, bending, torsion, and transverse shear deformations. A convected coordinate representation of the Cauchy stress tensor and a conjugate strain definition is introduced to model the beam deformation. To treat the beam dynamics, a two-stage modification of the central difference algorithm is presented to integrate the translational coordinates and the angular velocity vector. The angular orientation is then obtained from the application of an implicit integration algorithm to the Euler parameter/angular velocity kinematical relation. The combined developments of the objective internal force computation with the dynamic solution procedures result in the computational preservation of total energy for undamped systems. The present methodology is also extended to model the dynamics of deployment/retrieval of the flexible members. A moving spatial grid corresponding to the configuration of a deployed rigid beam is employed as a reference for the dynamic variables. A transient integration scheme which accurately accounts for the deforming spatial grid is derived from a space-time finite element discretization of a Hamiltonian variational statement. The computational results of this general deforming finite element beam formulation are compared to reported results for a planar inverse-spaghetti problem.
Directory of Open Access Journals (Sweden)
Volnei Tita
2001-10-01
Full Text Available This work proposes a procedure to estimate the dynamic damped behavior of fiber reinforced composite beams in flexural vibrations. A set of experimental dynamic tests were carried out in order to investigate the natural frequencies and modal shapes. These results are used to evaluate the damping factors by the program FREQ. These damping factors are then used as input to a damped dynamic analysis by the Finite Element Method, using Rayleigh Model. A good agreement between theoretical and experimental results was obtained. Thus, it became possible to validate the proposed procedure to evaluate dynamic damped behavior of composite beams.
Energy Technology Data Exchange (ETDEWEB)
Brown, Jason, E-mail: jason.brown@physics.ox.ac.uk [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Kocher, Paul; Ramanujan, Chandra S; Sharp, David N [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Torimitsu, Keiichi [NTT Basic Research Laboratories, NTT Corporation, Atsugi, 243-0198 (Japan); Ryan, John F [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom)
2013-10-15
We report on the fabrication of electrically conducting, ultra-sharp, high-aspect ratio probes for atomic force microscopy by electron-beam-induced deposition of platinum. Probes of 4.0 ±1.0 nm radius-of-curvature are routinely produced with high repeatability and near-100% yield. Contact-mode topographical imaging of the granular nature of a sputtered gold surface is used to assess the imaging performance of the probes, and the derived power spectral density plots are used to quantify the enhanced sensitivity as a function of spatial frequency. The ability of the probes to reproduce high aspect-ratio features is illustrated by imaging a close-packed array of nanospheres. The electrical resistance of the probes is measured to be of order 100 kΩ. - Highlights: • Electrically conducting, ultra-sharp, high aspect-ratio probes for AFM with radius-of-curvature 4.0±±1.0 nm. • AFM probe fabrication by electron-beam-induced deposition of platinum. • Enhanced spatial resolution demonstrated through AFM of sputtered gold grains. • AFM imaging of deep clefts and recesses on a close-packed array of nanospheres.
Dynamic scattering of electron vortex beams--a Bloch wave analysis.
Mendis, B G
2015-02-01
Two important applications of electron vortex beams are in electron magnetic chiral dichroism (EMCD) measurements and nanoparticle manipulation. In both cases orbital angular momentum (〈Lz〉) transfer between the vortex beam and the specimen due to dynamic scattering is critical. In general the 〈Lz〉 pendellösung consists of short and long wavelength oscillations. The former is due to interference between the tightly bound 1s and more dispersive non-1s Bloch states, while the latter is due to interference between the non-1s states. For EMCD experiments with ±ħ angular momentum beams, momentum transfer can be minimised by selecting the appropriate aperture size, so that the probe wavefunction approximately matches that of the 2p-type Bloch states. For manipulating nanoparticles with large angular momentum beams small apertures are required to excite the 1s state and thereby enhance the short wavelength oscillations in 〈Lz〉. This enables efficient momentum transfer to the specimen, provided the nanoparticle dimension corresponds to a minimum in the 〈Lz〉 pendellösung.
Static and Dynamic Experimental Analysis of the Galloping Stability of Porous H-Section Beams
Directory of Open Access Journals (Sweden)
F. Gandia
2014-01-01
Full Text Available The phenomenon of self-induced vibrations of prismatic beams in a cross-flow has been studied for decades, but it is still of great interest due to their important effects in many different industrial applications. This paper presents the experimental study developed on a prismatic beam with H-section. The aim of this analysis is to add some additional insight into the behaviour of the flow around this type of bodies, in order to reduce galloping and even to avoid it. The influence of some relevant geometrical parameters that define the H-section on the translational galloping behaviour of these beams has been analysed. Wind loads coefficients have been measured through static wind tunnel tests and the Den Hartog criterion applied to elucidate the influence of geometrical parameters on the galloping properties of the bodies under consideration. These results have been completed with surface pressure distribution measurements and, besides, dynamic tests have been also performed to verify the static criterion. Finally, the morphology of the flow past the tested bodies has been visualised by using smoke visualization techniques. Since the rectangular section beam is a limiting case of the H-section configuration, the results here obtained are compared with the ones published in the literature concerning rectangular configurations; the agreement is satisfactory.
Analysis of the Dynamic Response in Blast-Loaded CFRP-Strengthened Metallic Beams
Directory of Open Access Journals (Sweden)
Zhenyu Wang
2013-01-01
Full Text Available Carbon fiber-reinforced polymer composites (CFRPs are good candidates in enhancing the blast resistant performance of vulnerable public buildings and in reinforcing old buildings. The use of CFRP in retrofitting and strengthening applications is traditionally associated with concrete structures. Nevertheless, more recently, there has been a remarkable aspiration in strengthening metallic structures and components using CFRP. This paper presents a relatively simple analytical solution for the deformation and ultimate strength calculation of hybrid metal-CFRP beams when subjected to pulse loading, with a particular focus on blast loading. The analytical model is based on a full interaction between the metal and the FRP and is capable of producing reasonable results in a dynamic loading scenario. A nonlinear finite element (FE model is also developed to reveal the full dynamic behavior of the CFRP-epoxy-steel hybrid beam, considering the detailed effects, that is, large strains, high strain rates in metal, and different failure modes of the hybrid beam. Experimental results confirm the analytical and the FE results and show a strong correlation.
Beam Dynamics Studies and Design Optimisation of New Low Energy Antiproton Facilities
Resta-Lopez, Javier; Welsch, Carsten P
2016-01-01
Antiprotons, stored and cooled at low energies in a storage ring or at rest in traps, are highly desirable for the investigation of a large number of basic questions on fundamental interactions. This includes the static structure of antiprotonic atomic systems and the time-dependent quantum dynamics of correlated systems. The Antiproton Decelerator (AD) at CERN is currently the worlds only low energy antiproton factory dedicated to antimatter experiments. New antiproton facilities, such as the Extra Low ENergy Antiproton ring (ELENA) at CERN and the Ultra-low energy Storage Ring (USR) at FLAIR, will open unique possibilities. They will provide cooled, high quality beams of extra-low energy antiprotons at intensities exceeding those achieved presently at the AD by factors of ten to one hundred. These facilities, operating in the energy regime between 100 keV down to 20 keV, face several design and beam dynamics challenges, for example nonlinearities, space charge and scattering effects limiting beam life time....
Smith, David R; Yurduseven, Okan; Larouche, Stephane; Lipworth, Guy; Urzhumov, Yaroslav; Reynolds, Matthew S
2016-01-01
Wireless power transfer (WPT) has been an active topic of research, with a number of WPT schemes implemented in the near-field (coupling) and far-field (radiation) regimes. Here, we consider a beamed WPT scheme based on a dynamically reconfigurable source aperture transferring power to receiving devices within the Fresnel (near-zone) region. In this context, the dynamic aperture resembles a reconfigurable lens capable of focusing power to a well-defined spot, whose dimension can be related to a point spread function (PSF). Near-zone focusing can be achieved by generating different amplitude or phase profiles over the aperture, which can be realized using traditional architectures, such as phased arrays. Alternatively, metasurface guided-wave apertures can achieve dynamic focusing, with potentially lower cost implementations. We present an initial tradeoff analysis of the near-zone WPT concept, relating key parameters such as spot size, aperture size, wavelength, focal distance, and availability of sources. We...
D44 - Multiple beam SANS for dynamic studies on small sample volumes
International Nuclear Information System (INIS)
Tracking of kinetics and dynamical processes on extremely low sample volumes is one of the most promising fields for new applications of neutron scattering complementing synchrotron X-ray research. The proposed SANS instrument using multiple beams focussed on the sample is designed for investigations of nano-scaled fluctuations and sub-millisecond dynamics in new materials obtained only in small quantities from complex and expensive syntheses, such as biological or isotope enriched materials. It allows kinetics of chemical processes to be studied in a large dynamic range in one shot when fast changes of external parameters (B, H, T, p, pH, etc) has to be applied on small sample volumes
International Nuclear Information System (INIS)
Three-dimensional (3D) ordering of a charged-particle beams circulating in a storage ring is systematically studied with a molecular-dynamics simulation code. An ion beam can exhibit a 3D ordered configuration at ultralow temperature as a result of powerful 3D laser cooling. Various unique characteristics of the ordered beams, different from those of crystalline beams, are revealed in detail, such as the single-particle motion in the transverse and longitudinal directions, and the dependence of the tune depression and the Coulomb coupling constant on the operating points
Energy Technology Data Exchange (ETDEWEB)
Yuri, Yosuke, E-mail: yuri.yosuke@jaea.go.jp [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi Takasaki, Gunma 370-1292 Japan (Japan)
2015-06-29
Three-dimensional (3D) ordering of a charged-particle beams circulating in a storage ring is systematically studied with a molecular-dynamics simulation code. An ion beam can exhibit a 3D ordered configuration at ultralow temperature as a result of powerful 3D laser cooling. Various unique characteristics of the ordered beams, different from those of crystalline beams, are revealed in detail, such as the single-particle motion in the transverse and longitudinal directions, and the dependence of the tune depression and the Coulomb coupling constant on the operating points.
Vertical dynamic deflection measurement in concrete beams with the Microsoft Kinect.
Qi, Xiaojuan; Lichti, Derek; El-Badry, Mamdouh; Chow, Jacky; Ang, Kathleen
2014-01-01
The Microsoft Kinect is arguably the most popular RGB-D camera currently on the market, partially due to its low cost. It offers many advantages for the measurement of dynamic phenomena since it can directly measure three-dimensional coordinates of objects at video frame rate using a single sensor. This paper presents the results of an investigation into the development of a Microsoft Kinect-based system for measuring the deflection of reinforced concrete beams subjected to cyclic loads. New segmentation methods for object extraction from the Kinect's depth imagery and vertical displacement reconstruction algorithms have been developed and implemented to reconstruct the time-dependent displacement of concrete beams tested in laboratory conditions. The results demonstrate that the amplitude and frequency of the vertical displacements can be reconstructed with submillimetre and milliHz-level precision and accuracy, respectively. PMID:24556668
BEAM DYNAMICS ANALYSIS FOR THE ULTRA-FAST KICKER IN CIRCULAR COOLER RING OF JLEIC
Energy Technology Data Exchange (ETDEWEB)
Huang, Yulu [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Inst. Modern Phys., Chinese Academy of Sciences, Lanzhou, China; Wang, Haipeng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wang, Shaoheng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-05-01
An ultra-fast kicker system consisting of four quarter wavelength resonator based deflecting cavities was developed that simultaneously resonates at 10 subharmonic modes of the 476.3MHz bunch repetition frequency. Thus every 10th bunch in the bunch train will experience a transverse kick while all the other bunches are undisturbed. This fast kicker is being developed for the Energy Recovery Linac (ERL) based electron Circular Cooler Ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously MEIC). The electron bunches can be reused 10-30 turns thus the beam current in the ERL can be reduced to 1/10 - 1/30 (150mA - 50mA) of the cooling bunch current (1.5A). In this paper, several methods to synthesize such a kicker waveform and the comparison made by the beam dynamics tracking in Elegant will be discussed.
Energy Technology Data Exchange (ETDEWEB)
Emans, Joseph [Department of Engineering, Centre for Applied Dynamics Research, Fraser Noble Building, King' s College, University of Aberdeen, Aberdeen AB24 3UE, Scotland (United Kingdom); Wiercigroch, Marian [Department of Engineering, Centre for Applied Dynamics Research, Fraser Noble Building, King' s College, University of Aberdeen, Aberdeen AB24 3UE, Scotland (United Kingdom); Krivtsov, Anton M. [Department of Theoretical Mechanics, St. Petersburg State Polytechnical University, Politechnicheskaya Street 29, St. Petersburg 195251 (Russian Federation)
2005-03-01
The nonlinear analysis of a common beam system was performed, and the method for such, outlined and presented. Nonlinear terms for the governing dynamic equations were extracted and the behaviour of the system was investigated. The analysis was carried out with and without physically realistic parameters, to show the characteristics of the system, and the physically realistic responses. Also, the response as part of a more complex system was considered, in order to investigate the cumulative effects of nonlinearities. Chaos, as well as periodic motion was found readily for the physically unrealistic parameters. In addition, nonlinear behaviour such as co-existence of attractors was found even at modest oscillation levels during investigations with realistic parameters. When considered as part of a more complex system with further nonlinearities, comparisons with linear beam theory show the classical approach to be lacking in accuracy of qualitative predictions, even at weak oscillations.
International Nuclear Information System (INIS)
The nonlinear analysis of a common beam system was performed, and the method for such, outlined and presented. Nonlinear terms for the governing dynamic equations were extracted and the behaviour of the system was investigated. The analysis was carried out with and without physically realistic parameters, to show the characteristics of the system, and the physically realistic responses. Also, the response as part of a more complex system was considered, in order to investigate the cumulative effects of nonlinearities. Chaos, as well as periodic motion was found readily for the physically unrealistic parameters. In addition, nonlinear behaviour such as co-existence of attractors was found even at modest oscillation levels during investigations with realistic parameters. When considered as part of a more complex system with further nonlinearities, comparisons with linear beam theory show the classical approach to be lacking in accuracy of qualitative predictions, even at weak oscillations
Synchronous digitization for high dynamic range lock-in amplification in beam-scanning microscopy
Energy Technology Data Exchange (ETDEWEB)
Muir, Ryan D.; Sullivan, Shane Z.; Oglesbee, Robert A.; Simpson, Garth J., E-mail: gsimpson@purdue.edu [Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907 (United States)
2014-03-15
Digital lock-in amplification (LIA) with synchronous digitization (SD) is shown to provide significant signal to noise (S/N) and linear dynamic range advantages in beam-scanning microscopy measurements using pulsed laser sources. Direct comparisons between SD-LIA and conventional LIA in homodyne second harmonic generation measurements resulted in S/N enhancements consistent with theoretical models. SD-LIA provided notably larger S/N enhancements in the limit of low light intensities, through the smooth transition between photon counting and signal averaging developed in previous work. Rapid beam scanning instrumentation with up to video rate acquisition speeds minimized photo-induced sample damage. The corresponding increased allowance for higher laser power without sample damage is advantageous for increasing the observed signal content.
Synchronous digitization for high dynamic range lock-in amplification in beam-scanning microscopy
International Nuclear Information System (INIS)
Digital lock-in amplification (LIA) with synchronous digitization (SD) is shown to provide significant signal to noise (S/N) and linear dynamic range advantages in beam-scanning microscopy measurements using pulsed laser sources. Direct comparisons between SD-LIA and conventional LIA in homodyne second harmonic generation measurements resulted in S/N enhancements consistent with theoretical models. SD-LIA provided notably larger S/N enhancements in the limit of low light intensities, through the smooth transition between photon counting and signal averaging developed in previous work. Rapid beam scanning instrumentation with up to video rate acquisition speeds minimized photo-induced sample damage. The corresponding increased allowance for higher laser power without sample damage is advantageous for increasing the observed signal content
Energy Technology Data Exchange (ETDEWEB)
Buss, R.J.
1979-04-01
The study of seven radical-molecule reactions using the crossed molecular beam technique with supersonic nozzle beams is reported. Product angular and velocity distributions were obtained and compared with statistical calculations in order to identify dynamical features of the reactions. In the reaction of chlorine and fluorine atoms with vinyl bromide, the product energy distributions are found to deviate from predictions of the statistical model. A similar effect is observed in the reaction of chlorine atoms with 1, 2 and 3-bromopropene. The reaction of oxygen atoms with ICl and CF/sub 3/I has been used to obtain an improved value of the IO bond energy, 55.0 +- 2.0 kcal mol/sup -1/. In all reactions studied, the product energy and angular distributions are found to be coupled, and this is attributed to a kinematic effect of the conservation of angular momentum.
Evolutionary genetic optimization of the injector beam dynamics for the ERL test facility at IHEP
Yi, Jiao
2013-01-01
The energy recovery linac test facility (ERL-TF), a compact ERL-FEL (free electron laser) two-purpose machine, was proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector started with a photocathode direct-current gun was designed and preliminarily optimized. In this paper an evolutionary genetic method, non-dominated sorting genetic algorithm II, is applied to optimize the injector beam dynamics, especially in the high-charge operation mode. Study shows that using an incident laser with rms transverse size of 1~1.2 mm, the normalized emittance of the electron beam can be kept below 1 mm.mrad at the end of the injector. This work, together with the previous optimization for the low-charge operation mode by using the iterative scan method, provides guidance and confidence for future constructing and commissioning of the ERL-TF injector.
Neutron transport study of a beam port based dynamic neutron radiography facility
Khaial, Anas M.
Neutron radiography has the ability to differentiate between gas and liquid in two-phase flow due both to the density difference and the high neutron scattering probability of hydrogen. Previous studies have used dynamic neutron radiography -- in both real-time and high-speed -- for air-water, steam-water and gas-liquid metal two-phase flow measurements. Radiography with thermal neutrons is straightforward and efficient as thermal neutrons are easier to detect with relatively higher efficiency and can be easily extracted from nuclear reactor beam ports. The quality of images obtained using neutron radiography and the imaging speed depend on the neutron beam intensity at the imaging plane. A high quality neutron beam, with thermal neutron intensity greater than 3.0x 10 6 n/cm2-s and a collimation ratio greater than 100 at the imaging plane, is required for effective dynamic neutron radiography up to 2000 frames per second. The primary objectives of this work are: (1) to optimize a neutron radiography facility for dynamic neutron radiography applications and (2) to investigate a new technique for three-dimensional neutron radiography using information obtained from neutron scattering. In this work, neutron transport analysis and experimental validation of a dynamic neutron radiography facility is studied with consideration of real-time and high-speed neutron radiography requirements. A beam port based dynamic neutron radiography facility, for a target thermal neutron flux of 1.0x107 n/cm2-s, has been analyzed, constructed and experimentally verified at the McMaster Nuclear Reactor. The neutron source strength at the beam tube entrance is evaluated experimentally by measuring the thermal and fast neutron fluxes using copper activation flux-mapping technique. The development of different facility components, such as beam tube liner, gamma ray filter, beam shutter and biological shield, is achieved analytically using neutron attenuation and divergence theories. Monte
Tang, Bin
2008-01-01
A method has been developed for determining the transient response of a beam. The beam is divided into several continuous Timoshenko beam elements. The overall dynamic stiffness matrix is assembled in turn. Using Leung's equation, we derive the overall mass and stiffness matrices which are more suitable for response analysis than the overall dynamic stiffness matrix. The forced vibration of the beam is computed by the precise time integration method. Three illustrative beams are discussed to evaluate the performance of the current method. Solutions calculated by the finite element method and theoretical analysis are also enumerated for comparison. In these examples, we have found that the current method can solve the forced vibration of structures with a higher precision.
Egorov, E. N.; Hramov, A. E.
2006-08-01
The effect of the strength of the focusing magnetic field on chaotic dynamic processes occurring in an electron beam with a virtual cathode, as well as on the processes whereby the structures form in the beam and interact with each other, is studied by means of two-dimensional numerical simulations based on solving a self-consistent set of Vlasov-Maxwell equations. It is shown that, as the focusing magnetic field is decreased, the dynamics of an electron beam with a virtual cathode becomes more complicated due to the formation and interaction of spatiotemporal longitudinal and transverse structures in the interaction region of a vircator. The optimum efficiency of the interaction of an electron beam with the electromagnetic field of the vircator is achieved at a comparatively weak external magnetic field and is determined by the fundamentally two-dimensional nature of the motion of the beam electrons near the virtual cathode.
Numerical Simulations of Nonlinear Dynamics of Electron Cyclotron Maser with a Straight Beam
Institute of Scientific and Technical Information of China (English)
KONG Ling-Bao; HOU Zhi-Ling
2011-01-01
An electron cyclotron maser based on anomalous Doppler effect (ADECM) with an initially axial beam velocity is considered,and the nonlinear equation of beam-wave interaction is presented.With the numerical methods,the nonlinear dynamics of the ADECM is investigated.It is shown that the saturated interaction efficiency of the ADECM approaches 90％ and the interaction length for the saturated efficiency spans about 5-20cm.The results may be of importance for designing a compact device in applications in microwave generations or microwave heating of ceramic laminates.In the late 1950s,the theoretical studies on the instability of electron cyclotron maser based on normal Doppler effect (NDECM) were performed almost simultaneously by Gaponov,[1] Twiss,[2] and Schneider.[3] Their discoveries have resulted in the most successful fast-wave devices such as the gyrotron and variants.[4,5] The possible applications of microwaves span a wide range of technologies such as in thermonuclear fusion energy,charged particle accelerations,radar systems,and processing of advanced ceramics.[6-16]%An electron cyclotron maser based on anomalous Doppler effect (ADECM) with an initially axial beam velocity is considered, and the nonlinear equation of beam-wave interaction is presented. With the numerical methods, the nonlinear dynamics of the ADECM is investigated. It is shown that the saturated interaction efficiency of the ADECM approaches 90% and the interaction length for the saturated efficiency spans about 5-20 cm. The results may be of importance for designing a compact device in applications in microwave generations or microwave heating of ceramic laminates.
Damasceno, Juliana Ximenes; Couto, José Luciano Pimenta; Alves, Karla Shangela da Silva; Chaves, Cauby Maia; Costa, Fábio Wildson Gurgel; Pimenta, Alynne de Menezes Vieira; Fonteles, Cristiane Sá Roriz
2014-08-01
This article aims to report the main clinical aspects, cone beam computed tomography (CBCT) findings, and conservative oral rehabilitation in a child born from a consanguineous marriage who presented with Hallermann-Streiff syndrome (HSS) and generalized odontodysplasia. A 5-year-old girl presented with a diagnosis of HSS for oral evaluation. Radiographically, all teeth showed wide pulp chambers and roots with thin dentinal walls and open apices, resembling ghost teeth and indicating a diagnosis of odontodysplasia. Oral rehabilitation consisted of partial dentures that were regularly adjusted to conform the device with the pattern of growth and development of the child. CBCT scan provided great insight into HSS, allowing a detailed view of the morphologic aspects and associated trabecular bone pattern. Treatment of these 2 rare conditions in young children must consider the stage of growth and development. Although extremely rare in HSS, odontodysplasia should be investigated and conservatively managed in young children.
Dynamic Scaling in Growth of ZrO2 Thin Films Prepared by Electronic Beam Evaporation
Institute of Scientific and Technical Information of China (English)
齐红基; 黄立华; 袁景梅; 程传福; 邵建达; 范正修
2003-01-01
The growth front evolution of ZrO2 thin films deposited by electronic beam evaporation has been studied with atomic force microscopy. The dynamic scaling characteristics are observed during the deposition process. After numerical correlation analysis, the roughness exponent α = 0.80 ± 0.005 and the growth exponentβ = 0.141are all obtained. Based on these results, we suggest that the growth of ZrO2 thin films can be described by the combination of the Edwards-Wilkinson equation, the Mullins diffusion equation and the shadowing effect.
FAST TRACK COMMUNICATION: Relativistic echo dynamics and the stability of a beam of Landau electrons
Sadurní, E.; Seligman, T. H.
2008-03-01
We extend the concepts of echo dynamics and fidelity decay to relativistic quantum mechanics, specifically in the context of Klein-Gordon and Dirac equations under external electromagnetic fields. In both cases, we define similar expressions for the fidelity amplitude under perturbations of these fields and a covariant version of the echo operator. Transformation properties under the Lorentz group are established. An alternate expression for fidelity is given in the Dirac case in terms of a 4-current. As an application, we study a beam of Landau electrons perturbed by field inhomogeneities.
Relativistic echo dynamics and the stability of a beam of Landau electrons
Energy Technology Data Exchange (ETDEWEB)
SadurnI, E; Seligman, T H [Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico)], E-mail: sadurni@fis.unam.mx, E-mail: seligman@fis.unam.mx
2008-03-14
We extend the concepts of echo dynamics and fidelity decay to relativistic quantum mechanics, specifically in the context of Klein-Gordon and Dirac equations under external electromagnetic fields. In both cases, we define similar expressions for the fidelity amplitude under perturbations of these fields and a covariant version of the echo operator. Transformation properties under the Lorentz group are established. An alternate expression for fidelity is given in the Dirac case in terms of a 4-current. As an application, we study a beam of Landau electrons perturbed by field inhomogeneities. (fast track communication)
Nonlinear dynamics of magnetically coupled beams for multi-modal vibration energy harvesting
Abed, I.; Kacem, N.; Bouhaddi, N.; Bouazizi, M. L.
2016-04-01
We investigate the nonlinear dynamics of magnetically coupled beams for multi-modal vibration energy harvesting. A multi-physics model for the proposed device is developed taking into account geometric and magnetic nonlinearities. The coupled nonlinear equations of motion are solved using the Galerkin discretization coupled with the harmonic balance method and the asymptotic numerical method. Several numerical simulations have been performed showing that the expected performances of the proposed vibration energy harvester are significantly promising with up to 130 % in term of bandwidth and up to 60 μWcm-3g-2 in term of normalized harvested power.
Directory of Open Access Journals (Sweden)
Tufoi Marius
2014-07-01
Full Text Available This paper series presents an analysis regarding the dynamics of sandwich composite beams, embedded at one end, in order to highlight the effect of geometrical and material discontinuities upon the natural frequencies. In first part (Part I, analysis was performed with EulerBernoulli analytical method for determining the vibration modes and in second part (Part II, analysis was performed with numerical simulation in SolidWorks software for a five-layer composite. In the last section of the paper, an example is shown regarding how to interpret the obtained results.
Energy Technology Data Exchange (ETDEWEB)
Kucheyev, S. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2016-03-07
The major goal of this project is to develop and demonstrate a novel experimental approach to access the dynamic regime of radiation damage formation processes in nuclear materials. In particular, the project exploits a pulsed-ion-beam method in order to gain insight into defect interaction dynamics by measuring effective defect interaction time constants and defect diffusion lengths. For Year 2, this project had the following two major milestones: (i) measurement of the temperature dependence of defect dynamics in SiC and (ii) the evaluation of the robustness of the pulsed beam method from studies of the defect generation rate. As we describe below, both of these milestones have been met.
International Nuclear Information System (INIS)
The major goal of this project is to develop and demonstrate a novel experimental approach to access the dynamic regime of radiation damage formation processes in nuclear materials. In particular, the project exploits a pulsed-ion-beam method in order to gain insight into defect interaction dynamics by measuring effective defect interaction time constants and defect diffusion lengths. For Year 2, this project had the following two major milestones: (i) measurement of the temperature dependence of defect dynamics in SiC and (ii) the evaluation of the robustness of the pulsed beam method from studies of the defect generation rate. As we describe below, both of these milestones have been met.
Thorwarth, D.; Beyer, T.; Boellaard, R.; De Ruysscher, D.; Grgic, A.; Lee, J. A.; Pietrzyk, U.; Sattler, B.; Schaefer, A.; van Elmpt, W.; Vogel, W.; Oyen, W. J. G.; Nestle, U.
2012-01-01
This work addresses the clinical adoption of FDG-PET/CT for image-guided radiation therapy planning (RIP). As such, important technical and methodological aspects of PET/CT-based RIP are reviewed and practical recommendations are given for routine patient management and clinical studies. First, rece
Thorwarth, D.; Beyer, T.; Boellaard, R.; Ruysscher, D. de; Grgic, A.; Lee, J.A.; Pietrzyk, U.; Sattler, B.; Schaefer, A.; Elmpt, W. van; Vogel, W.; Oyen, W.J.G.; Nestle, U.
2012-01-01
This work addresses the clinical adoption of FDG-PET/CT for image-guided radiation therapy planning (RTP). As such, important technical and methodological aspects of PET/CT-based RTP are reviewed and practical recommendations are given for routine patient management and clinical studies. First, rece
Non-linear Dynamics in ETG Mode Saturation and Beam-Plasma Instabilities
Tokluoglu, Erinc K.
Non-linear mechanisms arise frequently in plasmas and beam-plasma systems resulting in dynamics not predicted by linear theory. The non-linear mechanisms can influence the time evolution of plasma instabilities and can be used to describe their saturation. Furthermore time and space averaged non-linear fields generated by instabilities can lead to collisionless transport and plasma heating. In the case of beam-plasma systems counter-intuitive beam defocusing and scaling behavior which are interesting areas of study for both Low-Temperature and High Energy Density physics. The non-linear mode interactions in form of phase coupling can describe energy transfer to other modes and can be used to describe the saturation of plasma instabilities. In the first part of this thesis, a theoretical model was formulated to explain the saturation mechanism of Slab Electron Temperature Gradient (ETG) mode observed in the Columbia Linear Machine (CLM), based on experimental time-series data collected through probe diagnostics [1]. ETG modes are considered to be a major player in the unexplained high levels of electron transport observed in tokamak fusion experiments and the saturation mechanism of these modes is still an active area of investigation. The data in the frequency space indicated phase coupling between 3 modes, through a higher order spectral correlation coefficient known as bicoherence. The resulting model is similar to [2], which was a treatment for ITG modes observed in the CLM and correctly predicts the observed saturation level of the ETG turbulence. The scenario is further supported by the fact that the observed mode frequencies are in close alignment with those predicted theoretical dispersion relations. Non-linear effects arise frequently in beam-plasma systems and can be important for both low temperature plasma devices commonly used for material processing as well as High Energy Density applications relevant to inertial fusion. The non-linear time averaged
Study of the transient effects of the space charge compensation on the dynamics of an intense beam
International Nuclear Information System (INIS)
A main interest in the design of ion accelerators is the control of the dynamics of intense beams at low energy. This dynamics is dominated by nonlinear effects of the Space Charge (SC) field. This SC field induces a halo formation which can induce losses along the transport. Once ionized by the beam, the residual gas, diffused by the source and produced by the desorption of the vacuum chamber of the accelerator, contributes to the production of electrons and ions. According to their sign of charge compared to the beam, these particles will be repelled or confined. The accumulation of particles in the beam contributes to the compensation of the SC field. However, this neutralization induces other non linearity which are dependent on time. This thesis presents an experimental and theoretical work of the SC compensation for ion beams (H+ and H-). The dynamics of these beams is modelled by a new PIC code, CARTAGO, ensuring the coupling between the created plasma and the studied beams. A single-particle study introduces the dynamics of the plasma in presence of the SC field and of an external magnetic field. The modeling of the compensation with the 1D version of CARTAGO code gave the establishment times and the compensation degrees for several cases of beams and various gas pressures. The compensation of a protons beam was studied more particularly in the low-energy line of the Injector of Protons of High Intensity (IPHI) at Saclay. Simulations show an over-compensation of the space charge inside the focusing solenoid and outside the compensation is only partial. Experimental confrontations of the 2D(r,z) modeling results in a part of this line are also detailed. (author)
Fine-tuning the etch depth profile via dynamic shielding of ion beam
Wu, Lixiang; Qiu, Keqiang; Fu, Shaojun
2016-08-01
We introduce a method for finely adjusting the etch depth profile by dynamic shielding in the course of ion beam etching (IBE), which is crucial for the ultra-precision fabrication of large optics. We study the physical process of dynamic shielding and propose a parametric modeling method to quantitatively analyze the shielding effect on etch depths, or rather the shielding rate, where a piecewise Gaussian model is adopted to fit the shielding rate profile. Two experiments were conducted. The experimental result of parametric modeling of shielding rate profiles shows that the shielding rate profile is significantly influenced by the rotary angle of the leaf. The result of the experiment on fine-tuning the etch depth profile shows good agreement with the simulated result, which preliminarily verifies the feasibility of our method.
Fine-tuning the etch depth profile via dynamic shielding of ion beam
Wu, Lixiang; Fu, Shaojun
2016-01-01
We introduce a method for finely adjusting the etch depth profile by dynamic shielding in the course of ion beam etching (IBE), which is crucial for the ultra-precision fabrication of large optics. We study the physical process of dynamic shielding and propose a parametric modeling method to quantitatively analyze the shielding effect on etch depths, or rather the shielding rate, where a piecewise Gaussian model is adopted to fit the shielding rate profile. We have conducted two experiments. In the experiment on parametric modeling of shielding rate profiles, its result shows that the shielding rate profile is significantly influenced by the rotary angle of the leaf. And the experimental result of fine-tuning the etch depth profile shows good agreement with the simulated result, which preliminarily verifies the feasibility of our method.
Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics
Energy Technology Data Exchange (ETDEWEB)
Alexahin, Y.; Gianfelice-Wendt, E.; Kapin, V.V.; /Fermilab
2012-05-01
In order to achieve peak luminosity of a Muon Collider (MC) in the 10{sup 35} cm{sup -2}s{sup -1} range very small values of beta-function at the interaction point (IP) are necessary ({beta}* {le} 1 cm) while the distance from IP to the first quadrupole can not be made shorter than {approx}6 m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of errors. In the present report we consider the effects on momentum acceptance and dynamic aperture of multipole field errors in the body of IR dipoles as well as of fringe-fields in both dipoles and quadrupoles in the ase of 1.5 TeV (c.o.m.) MC. Analysis shows these effects to be strong but correctable with dedicated multipole correctors.
Dynamical Dipole mode in heavy-ion fusion reactions by using stable and radioactive beams
International Nuclear Information System (INIS)
The existence of the dynamical dipole mode in the 192Pb composite system was investigated through the study of its prompt decay employing the 40Ca + 152Sm and 48Ca + 144Sm reactions at E(lab)=11 and 10.1 MeV/u, respectively. The γ-rays and light charged particles were detected in coincidence with evaporation residues and fission fragments. First results of this experiment show that the dynamical dipole mode survives in collisions involving heavier mass reaction partners than those studied previously. As a fast cooling mechanism on the fusion path, the prompt dipole radiation could be of interest for the synthesis of super-heavy elements through 'hot' fusion reactions. Furthermore, by using radioactive beams and the prompt radiation as a probe we could get information on the symmetry energy at sub-saturation densities. (authors)
Beam Dynamics Simulations of the REX-ISOLDE A/q-separator
Fraser, M A; Wenander, F
2014-01-01
The REX-ISOLDE A=q-separator selects the radioactive species of interest from the background of residual gas ions coming from the EBIS ion source. In the context of the HIE-ISOLDE upgrade, including the implementation of a multi-harmonic buncher and an upgraded EBIS, the separator and the beam line between the EBIS and RFQ, which we will call the Low Energy Beam Transfer (LEBT) line, has been simulated by tracking particles through the field maps of each active element using the TRACK [4] code. The simulations were benchmarked with a COSY-1 model that was improved to take into account the fringe fields of the electrostatic quadrupoles, electrostatic deflector and magnetic bender; the model can be used to tune and optimise the separator with higher-order effects taken into account. In this note the beam dynamics simulations are documented and the transverse and longitudinal acceptance of the separator line studied to provide design constraints for the EBIS upgrade.
J. Rodnizki, D. Berkovits, K. Lavie, I. Mardor, A. Shor and Y. Yanay (Soreq NRC, Yavne), K. Dunkel, C. Piel (ACCEL, Bergisch Gladbach), A. Facco (INFN/LNL, Legnaro, Padova), V. Zviagintsev (TRIUMF, Vancouver)
AbstractBeam dynamics simulations of SARAF (Soreq Applied Research Accelerator Facility) superconducting RF linear accelerator have been performed in order to establish the accelerator design. The multi-particle simulation includes 3D realistic electromagnetic field distributions, space charge forces and fabrication, misalignment and operation errors. A 4 mA proton or deuteron beam is accelerated up to 40 MeV with a moderated rms emittance growth and a high real-estate gradient of 2 MeV/m. An envelope of 40,000 macro-particles is kept under a radius of 1.1 cm, well below the beam pipe bore radius. The accelerator design of SARAF is proposed as an injector for the EURISOL driver accelerator. The Accel 176 MHZ β0=0.09 and β0=0.15 HWR lattice was extended to 90 MeV based on the LNL 352 MHZ β0=0.31 HWR. The matching between both lattices ensures smooth transition and the possibility to extend the accelerator to the required EURISOL ion energy.
Institute of Scientific and Technical Information of China (English)
Qiaoyun YAN; Hu DING; Liqun CHEN
2015-01-01
This investigation focuses on the nonlinear dynamic behaviors in the trans-verse vibration of an axially accelerating viscoelastic Timoshenko beam with the external harmonic excitation. The parametric excitation is caused by the harmonic fluctuations of the axial moving speed. An integro-partial-differential equation governing the transverse vibration of the Timoshenko beam is established. Many factors are considered, such as viscoelasticity, the finite axial support rigidity, and the longitudinally varying tension due to the axial acceleration. With the Galerkin truncation method, a set of nonlinear ordinary differential equations are derived by discretizing the governing equation. Based on the numerical solutions, the bifurcation diagrams are presented to study the effect of the external transverse excitation. Moreover, the frequencies of the two excitations are assumed to be multiple. Further, five different tools, including the time history, the Poincar´e map, and the sensitivity to initial conditions, are used to identify the motion form of the nonlinear vibration. Numerical results also show the characteristics of the quasiperiodic motion of the translating Timoshenko beam under an incommensurable re-lationship between the dual-frequency excitations.
Simulative research on the anode plasma dynamics in the high-power electron beam diode
Energy Technology Data Exchange (ETDEWEB)
Cai, Dan; Liu, Lie; Ju, Jin-Chuan; Zhang, Tian-Yang; Zhao, Xue-Long; Zhou, Hong-Yu [College of Optoelectric Science and Engineering, National University of Defense Technology, Hunan 410073 (China)
2015-07-15
Anode plasma generated by electron beams could limit the electrical pulse-length, modify the impedance and stability of diode, and affect the generator to diode power coupling. In this paper, a particle-in-cell code is used to study the dynamics of anode plasma in the high-power electron beam diode. The effect of gas type, dynamic characteristic of ions on the diode operation with bipolar flow model are presented. With anode plasma appearing, the amplitude of diode current is increased due to charge neutralizations of electron flow. The lever of neutralization can be expressed using saturation factor. At same pressure of the anode gas layer, the saturation factor of CO{sub 2} is bigger than the H{sub 2}O vapor, namely, the generation rate of C{sup +} ions is larger than the H{sup +} ions at the same pressure. The transition time of ions in the anode-cathode gap could be used to estimate the time of diode current maximum.
Martin, Claudio Torregrosa; Calviani, Marco; Muñoz-Cobo, José-Luis
2016-01-01
Antiprotons are produced at CERN by colliding a 26 GeV/c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 {\\deg}C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of...
Kar, S.; Ahmed, H.; Nersisyan, G.; Brauckmann, S.; Hanton, F.; Giesecke, A. L.; Naughton, K.; Willi, O.; Lewis, C. L. S.; Borghesi, M.
2016-05-01
As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ˜20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from a laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.
Beam dynamics of a double-gap acceleration cell for ion implantation with multiple atomic species
International Nuclear Information System (INIS)
As a result of our work on ion implantation, we derived equations for the beam dynamics of a two-gap-resonator cavity for accelerating and bunching various ion species of varying energies with the cavity designed for one particular ion species of a given energy (the design-reference particle). A two gap structure is useful at low resonant frequencies where lumped circuit elements (inductors) can be used and the structure kept small. A single gap structure has the advantage that each gap can be independently phased to produce the desired beam dynamics behavior for various ion species and ion energies. However at low frequencies, single gap resonant structures can be large. We find that the two-gap structure, where the phase difference between gaps, for the design reference particle, is fixed at π radians can give acceptable performance provided that the individual two gap cells in the entire accelerator are optimized for the ion species having the largest mass to charge ratio and having the maximum required output energy. Our equations show how to adjust the cavity phases and electric fields to obtain equivalent first-order accelerator performance for various ion species and energies. These equations allow for the effective evaluation of various accelerator concepts and can facilitate the tuning of a linac when changing energies and ion species. Extensive simulations have confirmed the efficacy of our equations. copyright 1997 American Institute of Physics
Martin, Claudio Torregrosa; Perillo-Marcone, Antonio; Calviani, Marco; Muñoz-Cobo, José-Luis
2016-07-01
Antiprotons are produced at CERN by colliding a 26 GeV /c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 °C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of end-of-pulse tensile waves and its relevance on the overall response (iii) A reduction of 44% in tensile pressure could be obtained by the use of a high density tantalum cladding.
Studying wedge factors and beam profiles for physical and enhanced dynamic wedges
Directory of Open Access Journals (Sweden)
Ahmad Misbah
2010-01-01
Full Text Available This study was designed to investigate variation in Varian′s Physical and Enhanced Dynamic Wedge Factors (WF as a function of depth and field size. The profiles for physical wedges (PWs and enhanced dynamic wedges (EDWs were also measured using LDA-99 array and compared for confirmation of EDW angles at different depths and field sizes. WF measurements were performed in water phantom using cylindrical 0.66 cc ionization chamber. WF was measured by taking the ratio of wedge and open field ionization data. A normalized wedge factor (NWF was introduced to circumvent large differences between wedge factors for different wedge angles. A strong linear dependence of PW Factor (PWF with depth was observed. Maximum variation of 8.9% and 4.1% was observed for 60° PW with depth at 6 and 15 MV beams respectively. The variation in EDW Factor (EDWF with depth was almost negligible and less than two per cent. The highest variation in PWF as a function of field size was 4.1% and 3.4% for thicker wedge (60° at 6 and 15 MV beams respectively and decreases with decreasing wedge angle. EDWF shows strong field size dependence and significant variation was observed for all wedges at both photon energies. Differences in profiles between PW and EDW were observed on toe and heel sides. These differences were dominant for larger fields, shallow depths, thicker wedges and low energy beam. The study indicated that ignoring depth and field size dependence of WF may result in under/over dose to the patient especially doing manual point dose calculation.
Egorov, E N
2006-01-01
The effect of the strength of the focusing magnetic field on chaotic dynamic processes occurring inan electron beam with a virtual cathode, as well as on the processes whereby the structures form in the beamand interact with each other, is studied by means of two-dimensional numerical simulations based on solving a self-consistent set of Vlasov-Maxwell equations. It is shown that, as the focusing magnetic field is decreased,the dynamics of an electron beam with a virtual cathode becomes more complicated due to the formation andinteraction of spatio-temporal longitudinal and transverse structures in the interaction region of a vircator. The optimum efficiency of the interaction of an electron beam with the electromagnetic field of the vircator isachieved at a comparatively weak external magnetic field and is determined by the fundamentally two-dimensional nature of the motion of the beam electrons near the virtual cathode.
Structural and growth aspects of electron beam physical vapor deposited NiO-CeO2 nanocomposite films
International Nuclear Information System (INIS)
Deposition of composite materials as thin film by electron beam physical vapor deposition technique (EB-PVD) still remains as a challenge. Here, the authors report the deposition of NiO-CeO2 (30/70 wt. %) composites on quartz substrate by EB-PVD. Two NiO-CeO2 nanocomposite targets—one as green compact and the other after sintering at 1250 °C—were used for the deposition. Though the targets varied with respect to physical properties such as crystallite size (11–45 nm) and relative density (44% and 96%), the resultant thin films exhibited a mean crystallite size in the range of 20–25 nm underlining the role of physical nature of deposition. In spite of the crystalline nature of the targets and similar elemental concentration, a transformation from amorphous to crystalline structure was observed in thin films on using sintered target. Postannealing of the as deposited film at 800 °C resulted in a polycrystalline structure consisting of CeO2 and NiO. Deposition using pure CeO2 or NiO as target resulted in the preferential orientation toward (111) and (200) planes, respectively, showing the influence of adatoms on the evaporation and growth process of NiO-CeO2 composite. The results demonstrate the influence of electron beam gun power on the adatom energy for the growth process of composite oxide thin films
An Automated High Aspect Ratio Mesher for Computational Fluid Dynamics Project
National Aeronautics and Space Administration — Computational fluid dynamics (CFD) simulations are routinely used while designing, analyzing, and optimizing air- and spacecraft. An important component of CFD...
Energy Technology Data Exchange (ETDEWEB)
Zeng, Han [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Xiong, Yongqian, E-mail: yqxiong@mail.hust.edu.cn [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Pei, Yuanji [National Synchrotron Radiation laboratory, University of Science and Technology of China, Hefei 230029, Anhui (China)
2014-11-11
The transport line used in a terahertz FEL device has to transport electron beam through the entire system efficiently and meet the requirements of the beam parameters at the undulator entrance. Due to space limitations, the size of the magnets (five quadrupoles and two bending magnets) employed in the transport line was limited, and some devices were densely packed. In this paper, analyses of the effect of fringe fields and magnetic interference of magnets are presented. 3D models of these magnets are built and their linear optical properties are compared with those obtained by hard edge models. The results indicated that the effects of these factors are significant and they would cause a mismatch of the beam at the exit of the transport line under the preliminary lattice design. To solve this problem, the beam was re-matched using the particle swarm optimization algorithm.
Study on Size-Dependent Young’s Modulus of a Silicon Nano beam by Molecular Dynamics Simulation
International Nuclear Information System (INIS)
Young’s modulus of a silicon nano beam with a rectangular cross-section is studied by molecular dynamics method. Dynamic simulations are performed for doubly clamped silicon nano beams with lengths ranging from 4.888 to 12.491 nm and cross-sections ranging from 1.22 nm ×1.22 nm to 3.39 nm × 3.39 nm. The results show that Young’s moduli of such small silicon nano beams are much higher than the value of Young’s modulus for bulk silicon. Moreover, the resonant frequency and Young’s modulus of the Si nano beam are strongly dependent not only on the size of the nano beam but also on surface effects. Young’s modulus increases significantly with the decreasing of the thickness of the silicon nano beam. This result qualitatively agrees with one of the conclusions based on a semi continuum model, in which the surface relaxation and the surface tension were taken into consideration. The impacts of the surface reconstruction with (2 ×1) dimmers on the resonant frequency and Young’s modulus are studied in this paper too. It is shown that the surface reconstruction makes the silicon nano beam stiffer than the one without the surface reconstruction, resulting in a higher resonant frequency and a larger Young’s modulus
Energy Technology Data Exchange (ETDEWEB)
Kovalenko, Oleksandr
2015-06-24
The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. A key part of a scientific program, along with antiproton physics, will be physics with highly-charged heavy ions. Phase-space cooled beams together with fixed internal target will provide an excellent environment for storage ring experiments at the HESR for the SPARC collaboration. Until recently, however, the existing ion optical lattice for the HESR was designed only for the experiments with antiproton beams. The thesis presents a new ion optical mode developed specifically for the operation of the HESR with highly charged heavy ions. The presence of the errors, such as beam momentum spread, magnetic field impurities or magnets misalignments, leads to disruption of beam dynamics: exciting of resonant motion and loss of beam stability. Within the paper, these effects are investigated with the help of numerical codes for particle accelerator design and simulation MAD-X and MIRKO. A number of correction techniques are applied to minimize the nonlinear impact on the beam dynamics and improve the experimental conditions. The application of the analytical and numerical tools is demonstrated in the experiment with uranium U{sup 90+} beam at the existing storage ring ESR, GSI.
International Nuclear Information System (INIS)
The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. A key part of a scientific program, along with antiproton physics, will be physics with highly-charged heavy ions. Phase-space cooled beams together with fixed internal target will provide an excellent environment for storage ring experiments at the HESR for the SPARC collaboration. Until recently, however, the existing ion optical lattice for the HESR was designed only for the experiments with antiproton beams. The thesis presents a new ion optical mode developed specifically for the operation of the HESR with highly charged heavy ions. The presence of the errors, such as beam momentum spread, magnetic field impurities or magnets misalignments, leads to disruption of beam dynamics: exciting of resonant motion and loss of beam stability. Within the paper, these effects are investigated with the help of numerical codes for particle accelerator design and simulation MAD-X and MIRKO. A number of correction techniques are applied to minimize the nonlinear impact on the beam dynamics and improve the experimental conditions. The application of the analytical and numerical tools is demonstrated in the experiment with uranium U90+ beam at the existing storage ring ESR, GSI.
Energy Technology Data Exchange (ETDEWEB)
Kuanr, Sushil Kumar; K, Suresh Babu, E-mail: sureshbabu.nst@pondiuni.edu.in [Centre for Nanoscience and Technology, Madanjeet School of Green Energy Technologies, Pondicherry University, Puducherry 605 014 (India)
2016-03-15
Deposition of composite materials as thin film by electron beam physical vapor deposition technique (EB-PVD) still remains as a challenge. Here, the authors report the deposition of NiO-CeO{sub 2} (30/70 wt. %) composites on quartz substrate by EB-PVD. Two NiO-CeO{sub 2} nanocomposite targets—one as green compact and the other after sintering at 1250 °C—were used for the deposition. Though the targets varied with respect to physical properties such as crystallite size (11–45 nm) and relative density (44% and 96%), the resultant thin films exhibited a mean crystallite size in the range of 20–25 nm underlining the role of physical nature of deposition. In spite of the crystalline nature of the targets and similar elemental concentration, a transformation from amorphous to crystalline structure was observed in thin films on using sintered target. Postannealing of the as deposited film at 800 °C resulted in a polycrystalline structure consisting of CeO{sub 2} and NiO. Deposition using pure CeO{sub 2} or NiO as target resulted in the preferential orientation toward (111) and (200) planes, respectively, showing the influence of adatoms on the evaporation and growth process of NiO-CeO{sub 2} composite. The results demonstrate the influence of electron beam gun power on the adatom energy for the growth process of composite oxide thin films.
Egorov, E. N.; Hramov, A. E.
2006-01-01
The effect of the strength of the focusing magnetic field on chaotic dynamic processes occurring inan electron beam with a virtual cathode, as well as on the processes whereby the structures form in the beamand interact with each other, is studied by means of two-dimensional numerical simulations based on solving a self-consistent set of Vlasov-Maxwell equations. It is shown that, as the focusing magnetic field is decreased,the dynamics of an electron beam with a virtual cathode becomes more ...
Reaction dynamics of Cl + butanol isomers by crossed-beam sliced ion imaging.
Estillore, Armando D; Visger-Kiefer, Laura M; Suits, Arthur G
2012-01-01
Butanol is now prominent among the prototype renewable biofuels. We have studied oxidation of a variety of butanol isomers under single collision conditions using chlorine atom as the oxidizing agent to gain detailed insight into the energetics and dynamics of these reactions. The interaction of chlorine atom radicals with butanol isomers: n-butanol, iso-butanol, sec-butanol, and tert-butanol have been studied by crossed-beam dc slice ion imaging techniques. The hydroxybutyl radicals generated from the H-abstraction processes were probed by single photon ionization using an F2 excimer laser. After background subtraction and density-to-flux correction of the raw images, translational energy distribution and product angular distributions were generated. At low collision energy, the hydroxyalkyl products are backscattered with respect to the alcohol beam and the scattering shifts to the forward direction as the collision energy is increased. The translational energy distributions are reminiscent to that of Cl + pentane reactions we studied earlier, i.e. a sharp forward peak -80% of the collision energy appears at the high collision energy. Isomer-specific details of the reactions will be discussed.
Entrance channel effect with stable and radioactive beams using dynamical cluster decay model
International Nuclear Information System (INIS)
The decay of hot and rotating 172Yb*, formed in two entrance channels 124Sn + 48Ca and 132Sn + 40Ca, is studied using the dynamical cluster-decay model. The effect of entrance channel, deformations (up to β2), barrier modification and fusion enhancement are addressed. The decay pattern of compound system, formed in different channels at comparable energy around the barrier, shows change in magnitude with structure remains almost same. There is an increase in the fusion probability with decrease in barrier modification, which leads to fusion enhancement at low energies. The higher ℓ values are contributing for 132Sn + 40Ca channel at lower energies as compare to 124Sn + 48Ca. It is inferred that with the use of stable and radioactive beam, forming same compound nucleus, the entrance channel dependence changes with the excitation energy
Beam dynamics simulations in laser electron storage rings and optical stochastic cooling
Duru, Alper
Laser-electron storage rings are potential compact X-ray sources. Longitudinal dynamics in laser-electron storage rings is studied including the effects of both laser interaction and synchrotron radiation. It is shown that the steady state energy spread can reach as high as a few percent. The main reason is the wide spread in the energy loss by electrons to laser photons. Optical stochastic cooling has been studied numerically. The effects of the finite bandwidth of the amplifier are mixing and signal distortion. Both are included in the simulations and the results are compared to theoretical results. It is shown that the beam can be cooled both in transverse and longitudinal phase phase spaces simultaneously.
Beam dynamics in resonant plasma wakefield acceleration at SPARC_LAB
Romeo, S.; Anania, M. P.; Chiadroni, E.; Croia, M.; Ferrario, M.; Marocchino, A.; Pompili, R.; Vaccarezza, C.
2016-09-01
Strategies to mitigate the increase of witness emittance and energy spread in beam driven plasma wakefield acceleration are investigated. Starting from the proposed resonant wakefield acceleration scheme in quasi-non-linear regime that is going to be carried out at SPARC_LAB, we performed systematic scans of the parameters to be used for drivers. The analysis will show that one of the main requirements to preserve witness quality during the acceleration is to have accelerating and focusing fields that are very stable during all the accelerating length. The difference between the dynamics of the leading bunch and the trailing bunch is pointed out. The classical condition on bunch length kpσz =√{ 2 } seems to be an ideal condition for the first driver within long accelerating lengths. The other drivers show to follow different longitudinal matching conditions. In the end a new method for the investigation of the matching for the first driver is introduced.
Studies of the chromatic properties and dynamic aperture of the BNL colliding beam accelerator
International Nuclear Information System (INIS)
The PATRICIA particle tracking program has been used to study chromatic effects in the Brookhaven CBA (Colliding Beam Accelerator). The short term behavior of particles in the CBA has been followed for particle histories of 300 turns. Contributions from magnet multipoles characteristic of superconducting magnets and closed orbit errors have been included in determining the dynamic aperture of the CBA for on and off momentum particles. The width of the third integer stopband produced by the temperature dependence of magnetization induced sextupoles in the CBA cable dipoles is evaluated for helium distribution systems having periodicity of one and six. The stopband width at a tune of 68/3 is naturally zero for the system having a periodicity of six and is ∫10-4 for the system having a periodicity of one. Results from theory are compared with results obtained with PATRICIA; the results agree within a factor of slightly more than two
Controlling quantum dynamics regardless of laser beam spatial profile and molecular orientation
Rabitz, Herschel; Turinici, Gabriel
2007-04-01
In a typical experiment aiming to control quantum dynamics phenomena, each molecule experiences the same temporal laser field, but with an amplitude that depends on the spatial location and orientation of the molecule in the laser beam. It is proved under commonly arising conditions that at least one optimal laser field exists which will control all molecules in the sample, regardless of their orientation or spatial location. The optimal laser field may consist of a multipolarization control containing up to three orthogonal, independently shaped components. The analysis also includes the prospect of multipartite control where the field couples distinct groupings of states (e.g., multiple vibronic states), but without direct coupling within a group of states. This conclusion shows that achieving quantum control is not a matter of striking a compromise over the sample diversity, but rather a task subject to optimization to reach the highest possible level of control for all molecules in the sample.
Exact dynamic stiffness matrix for flexural vibration of three-layered sandwich beams
Howson, W. P.; Zare, A.
2005-04-01
An exact dynamic member stiffness matrix (exact finite element), which defines the flexural motion of a three-layered sandwich beam with unequal faceplates, is developed from the closed form solution of the governing differential equation. This enables the powerful modelling features associated with the finite element technique to be utilised, including the ability to account for nodal masses, spring support stiffnesses and non-classical boundary conditions. However, such a formulation necessitates the solution of a transcendental eigenvalue problem. This is accomplished using the Wittrick-Williams algorithm, which enables the required natural frequencies to be converged upon to any required accuracy with the certain knowledge that none have been missed. The accuracy of the method is confirmed by comparison with three sets of published results and a final example indicates its range of application.
Prediction of dynamics of bellows in exhaust system of vehicle using equivalent beam modeling
Energy Technology Data Exchange (ETDEWEB)
Hong, Jin Ho; Kim, Yong Dae; Lee, Nam Young; Lee, Sang Woo [Noise and vibration CAE Team, Hyundai Motor Company, Ulsan (Korea, Republic of)
2015-11-15
The exhaust system is one of the major sources of vibrations, along with the suspension system and engine. When the exhaust system is connected directly to the engine, it transfers vibrations to the vehicle body through the body mounts. Therefore, in order to reduce the vibrations transmitted from the exhaust system, the vibration characteristics of the exhaust system should be predicted. Thus, the dynamic characteristics of the bellows, which form a key component of the exhaust system, must be modeled accurately. However, it is difficult to model the bellows because of the complicated geometry. Though the equivalent beam modeling technique has been applied in the design stage, it is not sufficiently accurate in the case of the bellows which have complicated geometries. In this paper, we present an improved technique for modeling the bellows in a vehicle. The accuracy of the modeling method is verified by comparison with the experimental results.
Tran Hy, J
1998-01-01
This thesis describes some new studies of the effects of cubic nonlinearities arising from image-charge forces and octupole magnets on the transverse beam dynamics of proton synchrotrons and storage rings, and also a study of the damping of coherent oscillations using a feed-back damper. In the latter case, various corrective algorithms were modeled using linear one-turn maps. Kicks of fixed amplitude but appropriate sign were shown to provide linear damping and no coherent tune shift, though the rate predicted analytically was somewhat higher than that observed in simulations. This algorithm gave much faster damping (for equal power) than conventional proportional kicks, which damp exponentially. Two single-particle effects of the image-change force were investigated: distortion of the momentum dispersion function and amplitude dependence of the betatron tunes (resulting in tune spread). The former is calculated using transfer maps and the method of undetermined coefficients, the latter by solving the cubic ...
Entrance channel effect with stable and radioactive beams using dynamical cluster decay model
Energy Technology Data Exchange (ETDEWEB)
Kumar, Raj, E-mail: rajkumarfzr@gmail.com [Dipartimento di Fisica “Galileo Galilei” and INFN, University of Padova, Padova-35131 (Italy); Jain, Deepika [School of Physics and Material Science, Thapar University, Patiala-147004 (India)
2014-09-15
The decay of hot and rotating {sup 172}Yb*, formed in two entrance channels {sup 124}Sn + {sup 48}Ca and {sup 132}Sn + {sup 40}Ca, is studied using the dynamical cluster-decay model. The effect of entrance channel, deformations (up to β{sub 2}), barrier modification and fusion enhancement are addressed. The decay pattern of compound system, formed in different channels at comparable energy around the barrier, shows change in magnitude with structure remains almost same. There is an increase in the fusion probability with decrease in barrier modification, which leads to fusion enhancement at low energies. The higher ℓ values are contributing for {sup 132}Sn + {sup 40}Ca channel at lower energies as compare to {sup 124}Sn + {sup 48}Ca. It is inferred that with the use of stable and radioactive beam, forming same compound nucleus, the entrance channel dependence changes with the excitation energy.
Dynamics of Plasma-Surface Interactions using In-situ Ion Beam Analysis
International Nuclear Information System (INIS)
The overall goal of this proposal was to develop an innovative experimental facility that would allow for the measurement of real-time response of a material surface to plasma bombardment by employing in-situ high-energy ion beam analysis. This facility was successfully developed and deployed at U. Wisconsin-Madison and was named DIONISOS (Dynamics of IONic Implantation and Sputtering on Surfaces). There were several major highlights to the DIONISOS research which we will briefly highlight below. The full technical details of the DIONISOS development, deployment and research results are contained in the Appendices which contain several peer-reviewed publications and a PhD thesis devoted to DIONISOS. The DIONISOS results on deuterium retention in molybdenum were chosen as an invited talk at the 2008 International Conference on Plasma-Surface Interactions in Toledo, Spain.
A Multimedia Tutorial for Charged-Particle Beam Dynamics. Final report
International Nuclear Information System (INIS)
In September 1995 WhistleSoft, Inc., began developing a computer-based multimedia tutorial for charged-particle beam dynamics under Phase II of a Small Business Innovative Research grant from the U.S. Department of Energy. In Phase I of this project (see its Final Report) we had developed several prototype multimedia modules using an authoring system on NeXTStep computers. Such a platform was never our intended target, and when we began Phase II we decided to make the change immediately to develop our tutorial modules for the Windows and Macintosh microcomputer market. This Report details our progress and accomplishments. It also gives a flavor of the look and feel of the presently available and upcoming modules
Self-Consistent 3D Modeling of Electron Cloud Dynamics and Beam Response
International Nuclear Information System (INIS)
We present recent advances in the modeling of beam electron-cloud dynamics, including surface effects such as secondary electron emission, gas desorption, etc, and volumetric effects such as ionization of residual gas and charge-exchange reactions. Simulations for the HCX facility with the code WARP/POSINST will be described and their validity demonstrated by benchmarks against measurements. The code models a wide range of physical processes and uses a number of novel techniques, including a large-timestep electron mover that smoothly interpolates between direct orbit calculation and guiding-center drift equations, and a new computational technique, based on a Lorentz transformation to a moving frame, that allows the cost of a fully 3D simulation to be reduced to that of a quasi-static approximation
Stability of graphene edges under electron beam: equilibrium energetics versus dynamic effects.
Kotakoski, Jani; Santos-Cottin, David; Krasheninnikov, Arkady V
2012-01-24
Electron beam of a transmission electron microscope can be used to alter the morphology of graphene nanoribbons and create atomically sharp edges required for applications of graphene in nanoelectronics. Using density-functional-theory-based simulations, we study the radiation hardness of graphene edges and show that the response of the ribbons to irradiation is not determined by the equilibrium energetics as assumed in previous experiments, but by kinetic effects associated with the dynamics of the edge atoms after impacts of energetic electrons. We report an unexpectedly high stability of armchair edges, comparable to that of pristine graphene, and demonstrate that the electron energy should be below ~50 keV to minimize the knock-on damage.
Added mass matrix estimation of beams partially immersed in water using measured dynamic responses
Liu, Fushun; Li, Huajun; Qin, Hongde; Liang, Bingchen
2014-09-01
An added mass matrix estimation method for beams partially immersed in water is proposed that employs dynamic responses, which are measured when the structure is in water and in air. Discrepancies such as mass and stiffness matrices between the finite element model (FEM) and real structure could be separated from the added mass of water by a series of correction factors, which means that the mass and stiffness of the FEM and the added mass of water could be estimated simultaneously. Compared with traditional methods, the estimated added mass correction factors of our approach will not be limited to be constant when FEM or the environment of the structure changed, meaning that the proposed method could reflect the influence of changes such as water depth, current, and so on. The greatest improvement is that the proposed method could estimate added mass of water without involving any water-related assumptions because all water influences are reflected in measured dynamic responses of the structure in water. A five degrees-of-freedom (dofs) mass-spring system is used to study the performance of the proposed scheme. The numerical results indicate that mass, stiffness, and added mass correction factors could be estimated accurately when noise-free measurements are used. Even when the first two modes are measured under the 5 percent corruption level, the added mass could be estimated properly. A steel cantilever beam with a rectangular section in a water tank at Ocean University of China was also employed to study the added mass influence on modal parameter identification and to investigate the performance of the proposed method. The experimental results demonstrated that the first two modal frequencies and mode shapes of the updated model match well with the measured values by combining the estimated added mass in the initial FEM.
Directory of Open Access Journals (Sweden)
John F. Hunt
2013-02-01
Full Text Available A new cantilever beam apparatus has been developed to measure static and vibrational properties of small and thin samples of wood or composite panels. The apparatus applies a known displacement to a cantilever beam, measures its static load, then releases it into its natural first mode of transverse vibration. Free vibrational tip displacements as a function of time were recorded. This paper compares the test results from the cantilever beam static bending and vibration with standard mid-point simply supported bending samples. Medium density fiberboard panels were obtained from four different commercial sources. Comparisons were made using a set of fiberboard panels with thicknesses of 8.1, 4.5, 3.7, and 2.6 mm and nominal densities of 700, 770, 780, and 830 kg/m3, respectively. Cantilever beam static modulus and dynamic modulus of elasticity linearly correlated well but were consistently higher than standard mid-point bending modulus of elasticity having linear correlations of 1.12:1 and 1.26:1, respectively. The higher strain rates of both the static and vibrating cantilever beam could be the primary reason for the slightly higher dynamic modulus values. The log decrement of the displacement was also used to calculate the damping ratio for the cantilever beam. As expected, damping ratio had a slightly decreasing slope as density increased. This paper discusses the new apparatus and initial results.
The dynamic aspects of thermo-elasto-viscoplastic snap-through and creep buckling phenomena
Riff, R.; Simitses, G. J.
1987-01-01
Use of a mathematical model and solution methodology, to examine dynamic buckling and dynamic postbuckling behavior of shallow arches and spherical caps made of a realistic material and undergoing non-isothermal, elasto-viscoplastic deformation was examined. Thus, geometric as well as material type nonlinearities of higher order are included in this analysis. The dynamic stability problem is studied under impulsive loading and suddenly applied loading with loads of constant magnitude and infinite duration. A finite element model was derived directly from the incrementally formulated nonlinear shell equations, by using a tensor-oriented procedure. As an example of the results, the time history of the midspan displacement of a damped shallow circular arch is presented.
Development of RFQ particle dynamics simulation tools and validation with beam tests
Energy Technology Data Exchange (ETDEWEB)
Maus, Johannes M.
2010-07-01
Two different strategies of designing RFQs have been introduced. The analytic description of the electric fields inside the quadrupole channel has been derived and the two term simplification was shown as well as the limitation of these approaches. The main work of this thesis was the implementation and analysis of a multigrid Poisson solver to describe the potential and electric field of RFQs which are needed to simulate the particle dynamics accurately. The main two ingredients of a multigrid Poisson solver are the ability of a Gauss-Seidel iteration method to smooth the error of an approximation within a few iteration steps and the coarse grid principle. The smoothing corresponds to a damping of the high frequency components of the error. After the smoothing, the error term can well be approximated on a coarser grid in which the low frequency components of the error on the fine grid are converted to high frequency errors on the coarse grid which can be damped further with the same Gauss-Seidel method. After implementation, the multigrid Poisson solver was analyzed using two different type of test problems: with and without a charge density. As a charge density, a homogeneously charged ball and cylinder were used to represent the bunched and unbunched beam and placed inside a quadruple channel. The solver showed a good performance. Next, the performance of the solver to calculate the external potentials (and fields) of RFQs was analyzed. Closing the analysis of the external field, the transmission and fraction of accelerated particles of the set of 12 RFQs for the two different methods were shown. In the last chapter of this thesis some experimental work on the MAFF (Munich Accelerator for Fission Fragments) IH-RFQ is described. The MAFF RFQ was designed to accelerate very neutron-rich fission fragments for various experiments. The machine was assembled in Frankfurt and a beam test stand was built. As a part of this thesis the shunt impedance of the structure was
Development of RFQ particle dynamics simulation tools and validation with beam tests
International Nuclear Information System (INIS)
Two different strategies of designing RFQs have been introduced. The analytic description of the electric fields inside the quadrupole channel has been derived and the two term simplification was shown as well as the limitation of these approaches. The main work of this thesis was the implementation and analysis of a multigrid Poisson solver to describe the potential and electric field of RFQs which are needed to simulate the particle dynamics accurately. The main two ingredients of a multigrid Poisson solver are the ability of a Gauss-Seidel iteration method to smooth the error of an approximation within a few iteration steps and the coarse grid principle. The smoothing corresponds to a damping of the high frequency components of the error. After the smoothing, the error term can well be approximated on a coarser grid in which the low frequency components of the error on the fine grid are converted to high frequency errors on the coarse grid which can be damped further with the same Gauss-Seidel method. After implementation, the multigrid Poisson solver was analyzed using two different type of test problems: with and without a charge density. As a charge density, a homogeneously charged ball and cylinder were used to represent the bunched and unbunched beam and placed inside a quadruple channel. The solver showed a good performance. Next, the performance of the solver to calculate the external potentials (and fields) of RFQs was analyzed. Closing the analysis of the external field, the transmission and fraction of accelerated particles of the set of 12 RFQs for the two different methods were shown. In the last chapter of this thesis some experimental work on the MAFF (Munich Accelerator for Fission Fragments) IH-RFQ is described. The MAFF RFQ was designed to accelerate very neutron-rich fission fragments for various experiments. The machine was assembled in Frankfurt and a beam test stand was built. As a part of this thesis the shunt impedance of the structure was
Stochastic aspects of one-dimensional discrete dynamical systems: Benford's law.
Snyder, M A; Curry, J H; Dougherty, A M
2001-08-01
Benford's law owes its discovery to the "Grubby Pages Hypothesis," a 19th century observation made by Simon Newcomb that the beginning pages of logarithm books were grubbier than the last few pages, implying that scientists referenced the values toward the front of the books more frequently. If a data set satisfies Benford's law, then it's significant digits will have a logarithmic distribution, which favors smaller significant digits. In this article we demonstrate two ways of creating discrete one-dimensional dynamical systems that satisfy Benford's law. We also develop a numerical simulation methodology that we use to study dynamical systems when analytical results are not readily available. PMID:11497692
DEFF Research Database (Denmark)
True, Hans; Engsig-Karup, Allan Peter; Bigoni, Daniele
2014-01-01
examples the dynamical problems are formulated as systems of ordinary differential-algebraic equations due to the geometric constraints. The non-smoothnesses have been neglected, smoothened or entered into the dynamical systems as switching boundaries with relations, which govern the continuation...... of the solutions across these boundaries. We compare the resulting solutions that are found with the three different strategies of handling the non-smoothnesses. Several integrators – both explicit and implicit ones – have been tested and their performances are evaluated and compared with respect to accuracy...
Investigations of Beam Dynamics Issues at Current and Future Hadron Accelerators
Energy Technology Data Exchange (ETDEWEB)
Ellison, James [Univ. of New Mexico, Albuquerque, NM (United States); Lau, Stephen [Univ. of New Mexico, Albuquerque, NM (United States); Heinemann, Klaus [Univ. of New Mexico, Albuquerque, NM (United States); Bizzozero, David [Univ. of New Mexico, Albuquerque, NM (United States)
2015-03-12
Final Report Abstract for DE-FG02-99ER4110, May 15, 2011- October 15, 2014 There is a synergy between the fields of Beam Dynamics (BD) in modern particle accelerators and Applied Mathematics (AMa). We have formulated significant problems in BD and have developed and applied tools within the contexts of dynamical systems, topological methods, numerical analysis and scientific computing, probability and stochastic processes, and mathematical statistics. We summarize the three main areas of our AMa work since 2011. First, we continued our study of Vlasov-Maxwell systems. Previously, we developed a state of the art algorithm and code (VM3@A) to calculate coherent synchrotron radiation in single pass systems. In this cycle we carefully analyzed the major expense, namely the integral-over-history (IOH), and developed two approaches to speed up integration. The first strategy uses a representation of the Bessel function J0 in terms of exponentials. The second relies on “local sequences” developed recently for radiation boundary conditions, which are used to reduce computational domains. Although motivated by practicality, both strategies involve interesting and rather deep analysis and approximation theory. As an alternative to VM3@A, we are integrating Maxwell’s equations by a time-stepping method, bypass- ing the IOH, using a Discontinuous Galerkin (DG) method. DG is a generalization of Finite Element and Finite Volume methods. It is spectrally convergent, unlike the commonly used Finite Difference methods, and can handle complicated vacuum chamber geometries. We have applied this in several contexts and have obtained very nice results including an explanation of an experiment at the Canadian Light Source, where the geometry is quite complex. Second, we continued our study of spin dynamics in storage rings. There is much current and proposed activity where spin polarized beams are being used in testing the Standard Model and its modifications. Our work has focused
International Nuclear Information System (INIS)
Very compact particle acceleration devices are based on ultra-intense electromagnetic fields that can be created in plasmas through the launching of intense relativistic charged-particle beams. An analysis of the transverse plasma wake field dynamics excited by a long relativistic electron beam is carried out in a purely local regime, in which the transverse beam spot-size is much bigger than the plasma wavelength. This is done by using the Vlasov equation, that governs the kinetic spatio-temporal evolution of the transverse paraxial beam transport. A self-consistent description of the beam dynamics is then provided by coupling the Vlasov equation with a Poisson-type equation. Furthermore, the latter relates the beam density with the plasma wake potential energy. Remarkably, the approach here proposed seems to be suitable for describing the beam self-modulation and the prediction of the beam collapse
Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator
International Nuclear Information System (INIS)
The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 (micro)s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.
Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator
Energy Technology Data Exchange (ETDEWEB)
Ekdahl, Carl A [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mccuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrato [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rowton, Lawrence [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Scarpetti, Raymond [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Hughes, Thomas [Los Alamos National Laboratory; Anaya, Richard [LLNL; Caporaso, George [LLNL; Chambers, Frank [LLNL; Chen, Yu - Jiuan [LLNL; Falabella, Steve [LLNL; Guethlein, Gary [LLNL; Raymond, Brett [LLNL; Richardson, Roger [LLNL; Trainham, C [NSTEC/STL; Watson, Jim [LLNL; Weir, John [LLNL; Genoni, Thomas [VOSS; Toma, Carsten [VOSS
2009-01-01
The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 {micro}s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.
DEFF Research Database (Denmark)
Li, Xiaozhou; Tapmeyer, Lukas; Bolte, Michael;
2016-01-01
The excellent results of dispersion-corrected density functional theory (DFT-D) calculations for static systems have been well established over the past decade. The introduction of dynamics into DFT-D calculations is a target, especially for the field of molecular NMR crystallography. Four 13C ss...
Becker, William J.; Cropanzano, Russell
2011-01-01
Previous research pertaining to job performance and voluntary turnover has been guided by 2 distinct theoretical perspectives. First, the push-pull model proposes that there is a quadratic or curvilinear relationship existing between these 2 variables. Second, the unfolding model of turnover posits that turnover is a dynamic process and that a…
Heuristic techniques for the analysis of variability as a dynamic aspect of change
Van Dijk, M.W.G.; Van Geert, P.
2011-01-01
Due to the influence of dynamic systems and microgenetic perspectives, variability is nowadays often seen as an important phenomenon that helps us understand the underlying mechanisms of development. This paper aims at demonstrating several simple techniques that can be used to analyse variability i
Kaur, Harpreet
2015-01-01
This paper illustrates how young children (ages 7-8, grade 2/3) can use the potential of dynamic geometry environments to develop an understanding of, and reasoning about, the properties and behaviours of different triangles (scalene, isosceles, equilateral). It provides a detailed description of a geometry unit, during which children worked both…
On the causality aspects of the dynamical Chern-Simons modified gravity
Porfirio, P J; Nascimento, J R; Petrov, A Yu
2016-01-01
We verify the consistency of the G\\"odel-type solutions within the dynamical Chern-Simons modified gravity in four dimensions, for different forms of matter including dust, fluid, scalar and electromagnetic fields and their combinations, and discuss the possibility of arising the closed timelike curves.
Hu, Y. J.; Yang, J.; Kitipornchai, S.
2013-07-01
This paper presents a geometrically nonlinear micro-beam model for the electro-dynamic analysis of an initially curved micro-beam under an applied voltage, with an emphasis on its snap-through and pull-in behaviors. The governing equations of motion and the associated boundary conditions are derived in an arc coordinate system without involving any assumptions on the nonlinear deformation. Differential quadrature method (DQM) and Petzold-Gear Backward Differentiation Formulas (BDF) are employed to solve the governing equations in the space and time domains respectively to obtain the nonlinear fundamental frequency, snap-through voltage, pull-in voltage and the corresponding mode shapes of a micro-beam clamped at both ends. The present analysis is validated through a direct comparison with the published experimental and numerical results. A parametric study is conducted to investigate the influences of the initial gap, base length, arc rise, and initial curved configuration on the snap-through and pull-in behaviors of the micro-beam.
Structural and Dynamical Aspects of the AdS/CFT Correspondence: a Rigorous Approach
Ribeiro, Pedro Lauridsen
2007-01-01
We elaborate a detailed study of certain aspects of (a version of) the AdS/CFT correspondence, conjectured by Maldacena and Witten, between quantum field theories in a gravitational background given by an asymptotically anti-de Sitter (AAdS) spacetime, and conformally covariant quantum field theories in the latter's conformal infinity (in the sense of Penrose), aspects such that: (a) are independent from (the pair of) specific models in Quantum Field Theory, and (b) susceptible to a recast in a mathematically rigorous mould. We adopt as a starting point the theorem demonstrated by Rehren in the context of Local Quantum Physics (also known as Algebraic Quantum Field Theory) in anti-de Sitter (AdS) spacetimes, called algebraic holography or Rehren duality. The main body of the present work consists in extending Rehren's result to a reasonably general class of d-dimensional AAdS spacetimes (d>3), scrutinizing how the properties of such an extension are weakened and/or modified as compared to AdS spacetime, and p...
Beam Dynamics in an Electron Lens with the Warp Particle-in-cell Code
Stancari, Giulio; Redaelli, Stefano
2014-01-01
Electron lenses are a mature technique for beam manipulation in colliders and storage rings. In an electron lens, a pulsed, magnetically confined electron beam with a given current-density profile interacts with the circulating beam to obtain the desired effect. Electron lenses were used in the Fermilab Tevatron collider for beam-beam compensation, for abort-gap clearing, and for halo scraping. They will be used in RHIC at BNL for head-on beam-beam compensation, and their application to the Large Hadron Collider for halo control is under development. At Fermilab, electron lenses will be implemented as lattice elements for nonlinear integrable optics. The design of electron lenses requires tools to calculate the kicks and wakefields experienced by the circulating beam. We use the Warp particle-in-cell code to study generation, transport, and evolution of the electron beam. For the first time, a fully 3-dimensional code is used for this purpose.
Dynamical aspects on FEL interaction in single passage and storage ring devices
Energy Technology Data Exchange (ETDEWEB)
Dattoli, G.; Renieri, A. [ENEA, Frascati (Italy)
1995-12-31
The dynamical behaviour of the free-electron lasers is investigated using appropriate scaling relations valid for devices operating in the low and high gain regimes, including saturation. The analysis is applied to both single passage and storage ring configurations. In the latter case the interplay between the interaction of the electron bean with the laser field and with the accelerator environment is investigated. In particular we discuss the effect of FEL interaction on the microwave instability.
Ecological Aspects of the Diversity Dynamics of North American Fossil Mammals
Tomiya, Susumu
2012-01-01
The dissertation research presented herein addresses two questions on possible ecological drivers of mammalian diversity dynamics at macroevolutionary time scales. The first question is whether key intrinsic biological traits that are tightly correlated with body size (e.g., reproductive rates) have strong influence on the extinction probability of mammalian taxa at the generic level. The second question is whether, within a regional mammalian fauna, the ecological composition of carnivores (...
Dynamic Responses of Supported Beams with Intermediate Supports Under Moving Loads
Directory of Open Access Journals (Sweden)
Biaobiao Zhang
2012-01-01
Full Text Available In this paper, a new beam shape function configuration method for determining transient responses of a finite Euler-Bernoulli beam with two intermediate supports excited by moving pressure wave loads is developed. To clarify this method, this beam structure is excited by the moving sinusoidal loads as an example. Transient responses of this beam structure are investigated and verified by the traditional finite element method. This method can be used to solve transient response problems of moving pressure loads exciting the beam structure with intermediate support. Actually it can be extended to solve other complicated beam structure problems.
Scaling aspects of the sea-ice-drift dynamics and pack fracture
Directory of Open Access Journals (Sweden)
A. Chmel
2007-05-01
Full Text Available A study of the sea-ice dynamics in the periods of time prior to and during the cycles of basin-wide fragmentation of the ice cover in the Arctic Ocean is presented. The fractal geometry of the ice-sheets limited by leads and ridges was assessed using the satellite images, while the data on the correlated sea-ice motion were obtained in the research stations "North Pole 32" and "North Pole 33" established on the ice pack. The revealed decrease of the fractal dimension as a result of large-scale fragmentation is consistent with the localization of the fracture process (leads propagation. At the same time, the scaling properties of the distribution of amplitudes of ice-fields accelerations were insensitive to the event of sea-ice fragmentation. The temporal distribution of the accelerations was scale-invariant during "quiet" periods of sea-ice drift but disordered in the period of mechanical perturbation. The period of decorrelated (in time ice-field motion during the important fracture event was interpreted as an inter-level transition in the hierarchic dynamical system. The mechanism of the long-range correlations in the sea-ice cover, including the fracture process, is suggested to be in relation with the self-organized oscillation dynamics inherent in the ice pack.
Dynamics of polymer nanoparticles through a single artificial nanopore with a high-aspect-ratio.
Cabello-Aguilar, Simon; Chaaya, Adib Abou; Bechelany, Mikhael; Pochat-Bohatier, Céline; Balanzat, Emmanuel; Janot, Jean-Marc; Miele, Philippe; Balme, Sébastien
2014-11-14
The development of nanometric Coulter counters for nanoparticle detection is an attractive and promising field of research. In this work, we have studied the influence of the nanopore surface state on charged polymer nanoparticle translocations. To make this, the translocation of carboxylate modified polystyrene microspheres (diameter 40, 70 and 100 nm) has been investigated through two kinds of high aspect ratio nanopores (negative and uncharged). The latter were tailored by a single track-etched and atomic layer deposition technique. It was shown that the mobility and the energy barrier are strongly dependent on nanopore surface charge. Typically if the latter exhibits negative surface charge, the microsphere mobility increases and the global energy barrier of entrance inside the nanopore decreases with its diameter, converse to the uncharged nanopore.
Energy Technology Data Exchange (ETDEWEB)
Reutter, Bryan W.; Gullberg, Grant T.; Huesman, Ronald H.
2001-04-09
The estimation of time-activity curves and kinetic model parameters directly from projection data is potentially useful for clinical dynamic single photon emission computed tomography (SPECT) studies, particularly in those clinics that have only single-detector systems and thus are not able to perform rapid tomographic acquisitions. Because the radiopharmaceutical distribution changes while the SPECT gantry rotates, projections at different angles come from different tracer distributions. A dynamic image sequence reconstructed from the inconsistent projections acquired by a slowly rotating gantry can contain artifacts that lead to biases in kinetic parameters estimated from time-activity curves generated by overlaying regions of interest on the images. If cone beam collimators are used and the focal point of the collimators always remains in a particular transaxial plane, additional artifacts can arise in other planes reconstructed using insufficient projection samples [1]. If the projection samples truncate the patient's body, this can result in additional image artifacts. To overcome these sources of bias in conventional image based dynamic data analysis, we and others have been investigating the estimation of time-activity curves and kinetic model parameters directly from dynamic SPECT projection data by modeling the spatial and temporal distribution of the radiopharmaceutical throughout the projected field of view [2-8]. In our previous work we developed a computationally efficient method for fully four-dimensional (4-D) direct estimation of spatiotemporal distributions from dynamic SPECT projection data [5], which extended Formiconi's least squares algorithm for reconstructing temporally static distributions [9]. In addition, we studied the biases that result from modeling various orders temporal continuity and using various time samplings [5]. the present work, we address computational issues associated with evaluating the statistical uncertainty of
Directory of Open Access Journals (Sweden)
Ahmad Mamandi
2014-01-01
Full Text Available The dynamic response of a Timoshenko beam with immovable ends resting on a nonlinear viscoelastic foundation and subjected to motion of a traveling mass moving with a constant velocity is studied. Primarily, the beam’s nonlinear governing coupled PDEs of motion for the lateral and longitudinal displacements as well as the beam’s cross-sectional rotation are derived using Hamilton’s principle. On deriving these nonlinear coupled PDEs the stretching effect of the beam’s neutral axis due to the beam’s fixed end conditions in conjunction with the von-Karman strain-displacement relations is considered. To obtain the dynamic responses of the beam under the act of a moving mass, derived nonlinear coupled PDEs of motion are solved by applying Galerkin’s method. Then the beam’s dynamic responses are obtained using mode summation technique. Furthermore, after verification of our results with other sources in the literature a parametric study on the dynamic response of the beam is conducted by changing the velocity of the moving mass, damping coefficient, and stiffnesses of the foundation including linear and cubic nonlinear parts, respectively. It is observed that the inclusion of geometrical and foundation stiffness nonlinearities into the system in presence of the foundation damping will produce significant effect in the beam’s dynamic response.
Lai, Steven H.-Y.
1992-01-01
A variational principle and a finite element discretization technique were used to derive the dynamic equations for a high speed rotating flexible beam-mass system embedded with piezo-electric materials. The dynamic equation thus obtained allows the development of finite element models which accommodate both the original structural element and the piezoelectric element. The solutions of finite element models provide system dynamics needed to design a sensing system. The characterization of gyroscopic effect and damping capacity of smart rotating devices are addressed. Several simulation examples are presented to validate the analytical solution.
Nonlinear dynamics for charges particle beams with a curved axis in the matrix - recursive model
Energy Technology Data Exchange (ETDEWEB)
Dymnikov, A.D. [University of St Petersburg, (Russian Federation). Institute of Computational Mathematics and Control Process
1993-12-31
In this paper a new matrix and recursive approach has been outlined for treating nonlinear optics of charged particle beams. This approach is a new analytical and computational tool for designers of optimal beam control systems. 9 refs.
Statistical and dynamical aspects in fission process: The rotational degrees of freedom
Indian Academy of Sciences (India)
Bency John
2015-08-01
In the final phases of fission process, there are fast collective rotational degrees of freedom, which can exert a force on the slower tilting rotational degree. Experimental observations that lead to this realization and theoretical studies that account for dynamics of the processes are discussed briefly. Supported by these studies, and by assuming a conditional equilibrium of the collective rotational modes at a pre-scission point, a new statistical model for fission fragment angular and spin distributions has been developed. This model gives a consistent description of the fragment angular and spin distributions for a wide variety of heavy- and light-ion-induced fission reactions.
Clustering aspects in N = Z nucleus 24Mg studied by antisymmetized molecular dynamics
International Nuclear Information System (INIS)
Cluster structure of highly excited states of 24Mg has been investigated by the antisymmetrized molecular dynamics. Imposing the constraints on the expectation values of harmonic oscillator quanta, α+20Ne, 12C+12C and 6α cluster wave functions were generated without any a priori assumption. The isoscalar monopole excitation function is also calculated and reasonably agrees with the observation. It is found that α+20Ne, 12C+12C and 6α clusters appear as the prominent peaks in the strength function
Dynamics of electron beams in the solar corona plasma with density fluctuations
Kontar, E. P.
2001-01-01
The problem of beam propagation in a plasma with small scale and low intensity inhomogeneities is investigated. It is shown that the electron beam propagates in a plasma as a beam-plasma structure and is a source of Langmuir waves. The plasma inhomogeneity changes the spatial distribution of the waves. The spatial distribution of the waves is fully determined by the distribution of plasma inhomogeneities. The possible applications to the theory of radio emission associated with electron beams...
Smulevich, A B
2000-01-01
An analysis of the interaction between pathocharacterological and psychopathological (affective, anxious-phobic and hysterical) phenomena within "borderline psychiatry" (reactions, phases, development) gives evidence to the existence of 2 clinically heterogeneous variations of comorbid interactions. The first variation: primary psychopathological syndromes manifesting without any significant correlation with personality disorders and transform into pathocharacterological ones (neurotic, postreactive) personality development by means of "amalgamating" mechanism. The second variation: secondary (in regard to personality disorders) psychopathological phenomena forming on the basis of constitutional personality traits by means of "splitting off" mechanism and are defined as personality disorders with predisposition to manifest positive psychopathological symptomatology. Formation of isolated obsessive and dissociative disorders within the structure of "basic" pathocharacterological phenomena (variation 2) predicts a future absence of growing severity of personality disorders (i.e. a dynamics traditionally defined as the development--variation 1) and stabilization of psychopathic traits with features of compensation of the latter. The possibilities of pathological dynamics in psychopathic personality with a "splitting off" of the isolated psychopathological syndromes exhausted; for decades neither growing severity of personality disorders, nor an exacerbation of those psychopathological complexes which provided a primary base for manifestation of positive symptomatology may be observed.
Institute of Scientific and Technical Information of China (English)
Gao Xiguang; Song Yingdong; Sun Zhigang; Hu Xuteng
2010-01-01
A multiscale method for simulating the dynamic response of ceramic matrix composite (CMC) with matrix cracks is developed.At the global level,the finite element method is employed to simulate the dynamic response ofa CMC beam.While at the local level,the multiscale mechanical method is used to estimate the stress/strain response of the material.A distributed computing system is developed to speed up the simulation.The simulation of dynamic response of a Nicalon/CAS-Ⅱ beam being subjected to harmonic loading is performed as a numerical example.The results show that both the stress/strain responses under tension and compressive loading are nonlinear.These conditions result in a different response compared with that of elastic beam,such as:1) the displacement response is not symmetric about the axis of time;2) in the condition of small external load,the response at first order natural frequency is limited within a finite range;3) decreasing the matrix crack space will increase the displacement response of the beam.
Reaction dynamics induced by the radioactive ion beam 7Be on medium-mass and heavy targets
International Nuclear Information System (INIS)
We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam 7Be (Sα = 1.586 MeV) on medium-mass (58Ni) and heavy (208Pb) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3×105 pps 7Be secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems
International Nuclear Information System (INIS)
Characteristics of charged-particle emission in heavy-ion reactions have been studied in the framework of the semiclassical Landau-Vlasov approach for the 40Ar + 27Al collisions at 65 MeV/u. The reaction mechanism is dominated by binary dissipative collisions. After an abundant prompt emission coming from the overlapping region between the target and the projectile, two excited nuclei, the quasi-target and the quasi-projectile, emerge from the collision. To shed some light on the role played by dynamical effects, light-charged particle observables, which are currently used as an experimental signature a of hot equilibrated nucleus, have been carefully investigated. (K.A.)
International Nuclear Information System (INIS)
A computer code for the dynamic analysis of the proposed 500 MWe Pressurised Heavy Water Reactor is being developed. One of the modules of this code deals with the primary heat transport system pressure control. A thermal hydraulic model of the pressure control system has been developed. This model includes the following : reactor coolant loop, primary circulating pump, Core heat transfer, Feed/bleed with Bleed Condenser and pressure controller. Analysis has been carried out for transients like change in reactor power, leakage from the primary heat transport system and malfunctioning of control system. The mathematical model is presented in the paper along with the results obtained for some of the transients analysed. (author). 6 refs., 6 figs
Selected aspects of fusion reactions
Energy Technology Data Exchange (ETDEWEB)
Lacroix, D
2003-01-01
In this lecture, we present selected aspects of nuclear fusion. The importance of the initial geometry of the reaction and its relation to fusion barrier are first discussed. The effect of deformation leading to the notion of barrier distribution is then illustrated. After a brief overview of the advantages of macroscopic theories, the dynamics of nuclear system under large amplitude motion is reviewed. The di-nuclear concept is presented to understand the competition between fusion and quasi-fission. This concept is then generalized to account for the dissipative dynamics in multidimensional collective space. The last part of this lecture is devoted to new aspects encountered with radioactive beams specific properties of very extended neutron rich system, influence of pygmy or soft dipole resonances and charge exchange far from stability are discussed. (author)
Respiratory-triggered electron beam CT with integrated spirometry for evaluation of dynamic airflow
McNitt-Gray, Michael F.; Goldin, Jonathan G.; Welch, Mike; Szold, Oded; Levine, Michael; Aberle, Denise R.
1996-04-01
The purpose is to integrate time-attenuation curves from Electron-Beam CT with flow-time curves from spirometry in the analysis of airflow obstruction. A pressure-sensitive switch was connected between a spirometer mouthpiece and a modified EBCT scanner keyboard. The onset of expiratory flow causes pressure changes which simultaneously trigger EBCT and spirometric acquisitions. Subjects performed a forced expiratory maneuver, during which EBCT images of the lung were obtained every 500 ms using 130 kVp, 630 mA, 100 ms scan time and 3 mm collimation. From EBCT images, time-attenuation curves were generated for each of three zones (non-dependent, middle and dependent lung) using small ROIs (12 mm2) placed over approximately the same anatomic regions of lung. The resulting time- attenuation curves and flow-time curves were then superimposed. Two normal subjects, two subjects with emphysema and three lung transplant subjects have been studied to date. In normal subjects, lung attenuation increases steadily during the first 4 - 6 seconds of expiration, whereas in patients with emphysema, lung attenuation was relatively constant over the course of expiration. Lung transplant subjects show both of these characteristics--normal characteristics for the transplant lung and emphysematous characteristics for the native lung. Lung transplant subjects may also demonstrate some dynamics between transplant and diseased lung. Respiratory-triggered EBCT can be used to simultaneously acquire time-attenuation and flow-time data. This has been used to characterize dynamic airflow patterns in patients with respiratory disease.
Electronic shell structure and carrier dynamics of high aspect ratio InP single quantum dots
Beirne, Gareth J.; Reischle, Matthias; Roßbach, Robert; Schulz, Wolfgang-Michael; Jetter, Michael; Seebeck, Jan; Gartner, Paul; Gies, Christopher; Jahnke, Frank; Michler, Peter
2007-05-01
Systematic excitation-power-density dependent and time-resolved single-dot photoluminescence studies have been performed on type-I InP/Ga0.51In0.49P quantum dots. These dots are rather flat and therefore exhibit larger than normal single-dot ground-state transition energies ranging from 1.791 to 1.873eV . As a result of their low height, the dots have a very high aspect ratio (ratio of width to height) of approximately 27:1 . In general, even at high excitation power densities, the dots with ground-state transition energies above 1.82eV exhibit only s -shell emission, while the larger dots exhibiting ground-state emission below 1.82eV tend to exhibit emission from several (in some cases up to eight) shells. Calculations indicate that this change is due to the smaller dots having only one confined election level while the larger dots have two or more. Time-resolved investigations indicate the presence of fast carrier relaxation and recombination processes for both dot types, however, only the larger dots display clear interlevel relaxation effects as expected. The temporal behavior has been qualitatively simulated using a rate equation model. Also, in a more detailed analysis, the fast carrier relaxation is described on the basis of a quantum kinetic treatment of the carrier-phonon interaction. Finally, the dots display a clear single-photon emission signature in photon statistics measurements.
Energy Technology Data Exchange (ETDEWEB)
Welsch, Dominic Markus
2010-03-10
The High-Energy Storage Ring (HESR) is part of the upcoming Facility for Antiproton and Ion Research (FAIR) which is planned as a major extension to the present facility of the Helmholtzzentrum fuer Schwerionenforschung (GSI) in Darmstadt. The HESR will provide antiprotons in the momentum range from 1.5 to 15 GeV/c for the internal target experiment PANDA. The demanding requirements of PANDA in terms of beam quality and luminosity together with a limited production rate of antiprotons call for a long beam life time and a minimum of beam loss. Therefore, an effective closed orbit correction and a sufficiently large dynamic aperture of the HESR are crucial. With this thesis I present my work on both of these topics. The expected misalignments of beam guiding magnets have been estimated and used to simulate the closed orbit in the HESR. A closed orbit correction scheme has been developed for different ion optical settings of the HESR and numerical simulations have been performed to validate the scheme. The proposed closed orbit correction method which uses the orbit response matrix has been benchmarked at the Cooler Synchrotron COSY of the Forschungszentrum Juelich. A chromaticity correction scheme for the HESR consisting of sextupole magnets has been developed to reduce tune spread and thus to minimize the emittance growth caused by betatron resonances. The chromaticity correction scheme has been optimized through dynamic aperture calculations. The estimated field errors of the HESR dipole and quadrupole magnets have been included in the non-linear beam dynamics studies. Investigations concerning their optimization have been carried out. The ion optical settings of the HESR have been improved using dynamic aperture calculations and the technique of frequency map analysis. The related diffusion coefficient was also used to predict long-term stability based on short-term particle tracking. With a reasonable reduction of the quadrupole magnets field errors and a
Caddemi, S.; Caliò, I.
2013-06-01
In this paper the closed form expression of the exact dynamic stiffness matrix of an Euler-Bernoulli beam in the presence of an arbitrary number of concentrated cracks is derived. The procedure adopted for the evaluation of the dynamic stiffness matrix is based on the availability of the exact closed form solution of the vibration modes of the multi-cracked beam, derived by the same authors in a previous paper. The knowledge of the exact explicit dynamic stiffness matrix of the multi-cracked beam makes the direct evaluation of the exact global dynamic stiffness matrix of damaged frame structures possible. Furthermore, it allows the exact evaluation of the frequencies and the corresponding vibration modes, consistent with the distributed parameter model, through the application of the well-known Wittrick-Williams algorithm. Some numerical applications, relative to the evaluation of frequencies and the corresponding mode shapes of multi-cracked framed structure, are reported. Furthermore, the closed-form solution has been validated by comparing with some exact results available in the literature, for a simple single cracked frame. Finally, further new results for a multi-cracked frame have been compared with those obtained by a finite element simulation.
Bernhard, Axel; Casalbuoni, Sara; Ferracin, Paolo; Garcia Fajardo, Laura; Gerstl, Stefan; Gethmann, Julian; Grau, Andreas; Huttel, Erhard; Khrushchev, Sergey; Mezentsev, Nikolai; Müller, Anke-Susanne; Papaphilippou, Yannis; Saez de Jauregui, David; Schmickler, Hermann; Schoerling, Daniel; Shkaruba, Vitaliy; Smale, Nigel; Tsukanov, Valery; Zisopoulos, Panagiotis; Zolotarev, Konstantin
2016-01-01
In a collaboration between CERN, BINP and KIT a prototype of a superconducting damping wiggler for the CLIC damping rings has been installed at the ANKA synchrotron light source. On the one hand, the foreseen experimental program aims at validating the technical design of the wiggler, particularly the conduction cooling concept applied in its cryostat design, in a long-term study. On the other hand, the wiggler's influence on the beam dynamics particularly in the presence of collective effects is planned to be investigated. ANKA's low-alpha short-bunch operation mode will serve as a model system for these studies on collective effects. To simulate these effects and to make verifiable predictions an accurate model of the ANKA storage ring in low-alpha mode, including the insertion devices is under parallel development. This contribution reports on the first operational experience with the CLIC damping wiggler prototype in the ANKA storage ring and steps towards the planned advanced experimental program with th...
aSi EPIDs for the in-vivo dosimetry of static and dynamic beams
Piermattei, A.; Cilla, S.; Azario, L.; Greco, F.; Russo, M.; Grusio, M.; Orlandini, L.; Fidanzio, A.
2015-10-01
Portal imaging by amorphous silicon (aSi) photodiode is currently the most applied technology for in-vivo dosimetry (IVD) of static and dynamic radiotherapy beams. The strategy, adopted in this work to perform the IVD procedure by aSi EPID, is based on: in patient reconstruction of the isocenter dose and day to day comparison between 2D-portal images to verify the reproducibility of treatment delivery. About 20.000 tests have been carried out in this last 3 years in 8 radiotherapy centers using the SOFTDISO program. The IVD results show that: (i) the procedure can be implemented for linacs of different manufacturer, (ii) the IVD analysis can be obtained on a computer screen, in quasi real time (about 2 min after the treatment delivery) and (iii) once the causes of the discrepancies were eliminated, all the global IVD tests for single patient were within the acceptance criteria defined by: ±5% for the isocenter dose, and PγFisica Nucleare (INFN) and Università Cattolica del S.Cuore (UCSC).
Generalized warping effect in the dynamic analysis of beams of arbitrary cross section
Dikaros, I. C.; Sapountzakis, E. J.; Argyridi, A. K.
2016-05-01
In this paper a general formulation for the nonuniform warping dynamic analysis of beams of arbitrary simply or multiply connected cross section, under arbitrary external loading and general boundary conditions is presented taking into account the effects of rotary and warping inertia. The nonuniform warping distributions are taken into account by employing four independent warping parameters multiplying a shear warping function in each direction and two torsional warping functions, respectively, which are obtained by solving the corresponding boundary value problems, formulated exploiting the longitudinal local equilibrium equation. A shear stress "correction" is also performed in order to improve the stress field arising from the employed kinematical considerations. Ten initial boundary value problems are formulated with respect to the displacement and rotation components as well as to the independent warping parameters and solved using the Analog Equation Method, a Boundary Element Method based technique in combination with an appropriate time integration scheme. The warping functions and the geometric constants including the additional ones due to warping are evaluated employing a pure BEM approach.
Strong-field isomerization dynamics of fast beams of hydrocarbon ions
Jochim, Bethany; Rajput, Jyoti; Berry, Ben; Severt, T.; Zohrabi, M.; Feizollah, Peyman; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I.
2016-05-01
Bond rearrangement and fragmentation of hydrocarbons in intense laser fields has been a topic of considerable interest in the strong-field community in recent years. We study the interactions of keV hydrocarbon ion beams with ultrafast, intense laser pulses, employing coincidence 3D momentum imaging to elucidate the fragmentation dynamics and identify laser parameters that might be used for controlling outcomes such as the branching ratios. We focus on dissociation to ensure that isomerization occurs on the particular electronic channels of the molecular ion investigated. In C2 H2+, for example, we measure the intensity-dependent branching ratios of the acetylene (CH++CH) and vinylidene (e . g . , C++ CH2) channels. The relative fragmentation rates between the acetylene and vinylidene channels change by a factor of ~ 2 over the range of experimental intensities (1013- 1015 W/ cm2). Other hydrocarbons of interest include not only cations but also anions, such as C2 H 2 -. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy. BJ was also supported in part by DOE-SCGF (DE-AC05-06OR23100).
aSi EPIDs for the in-vivo dosimetry of static and dynamic beams
Energy Technology Data Exchange (ETDEWEB)
Piermattei, A. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); Istituto di Fisica e U.O.C. di Fisica Sanitaria, Università Cattolica del S. Cuore, 00168 Roma (Italy); Cilla, S. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); U.O. di Fisica Sanitaria, Fondazione per la Ricerca e Cura ‘Giovanni Paolo II’, 86100 Campobasso (Italy); Azario, L.; Greco, F. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); Istituto di Fisica e U.O.C. di Fisica Sanitaria, Università Cattolica del S. Cuore, 00168 Roma (Italy); Russo, M. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); U.O. di Fisica Sanitaria, Ospedale Belcolle, 01100 Viterbo (Italy); Grusio, M. [Istituto di Fisica e U.O.C. di Fisica Sanitaria, Università Cattolica del S. Cuore, 00168 Roma (Italy); Orlandini, L. [U.O. di Fisica Medica, Centro Oncologico Fiorentino, 50121 Firenze (Italy); Fidanzio, A., E-mail: andrea.fidanzio@rm.unicatt.it [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); Istituto di Fisica e U.O.C. di Fisica Sanitaria, Università Cattolica del S. Cuore, 00168 Roma (Italy)
2015-10-01
Portal imaging by amorphous silicon (aSi) photodiode is currently the most applied technology for in-vivo dosimetry (IVD) of static and dynamic radiotherapy beams. The strategy, adopted in this work to perform the IVD procedure by aSi EPID, is based on: in patient reconstruction of the isocenter dose and day to day comparison between 2D-portal images to verify the reproducibility of treatment delivery. About 20.000 tests have been carried out in this last 3 years in 8 radiotherapy centers using the SOFTDISO program. The IVD results show that: (i) the procedure can be implemented for linacs of different manufacturer, (ii) the IVD analysis can be obtained on a computer screen, in quasi real time (about 2 min after the treatment delivery) and (iii) once the causes of the discrepancies were eliminated, all the global IVD tests for single patient were within the acceptance criteria defined by: ±5% for the isocenter dose, and P{sub γ<1}≥90% of the checked points for the 2D portal image γ-analysis. This work is the result of a project supported by the Istituto Nazionale di Fisica Nucleare (INFN) and Università Cattolica del S.Cuore (UCSC)
Arboleda-Monsalve, Luis G.; Zapata-Medina, David G.; Aristizabal-Ochoa, J. Darío
2008-03-01
The dynamic-stiffness matrix and load vector of a Timoshenko beam-column resting on a two-parameter elastic foundation with generalized end conditions are presented. The proposed model includes the frequency effects on the stiffness matrix and load vector as well as the coupling effects of: (1) bending and shear deformations along the member; (2) translational and rotational lumped masses at both ends; (3) translational and rotational masses uniformly distributed along its span; (3) axial load (tension or compression) applied at both ends; and (4) shear forces along the span induced by the applied axial load as the beam deforms according to the "modified shear equation" proposed by Timoshenko. The dynamic analyses of framed structures can be performed by including the effects of the imposed frequency ( ω>0) on the dynamic-stiffness matrix and load vector while the static and stability analyses can be carried out by making the frequency ω=0. The proposed model and corresponding dynamic-stiffness matrix and load vector represent a general solution capable to solve, just by using a single segment per element, the static, dynamic and stability analyses of any elastic framed structure made of prismatic beam-columns with semi-rigid connections resting on two-parameter elastic foundations. Analytical results indicate that the elastic behavior of framed structures made of beam-columns is frequency dependent and highly sensitive to the coupling effects just mentioned. Three comprehensive examples are presented to show the capacities and validity of the proposed method and the obtained results are compared with the finite element method and other analytical approaches.
Aspects on the Dynamics and Detection of Additional Circumbinary Extrasolar Planets
Hinse, Tobias C.; Haghighipour, Nader; Goździewski, Krzysztof
2014-04-01
The presence of additional bodies orbiting a binary star system can be detected by monitoring the binary's eclipse timing. These so-called circumbinary objects will reveal themselves by i) either introducing a reflex motion of the binary system about the total system's barycenter creating a geometric light-travel time effect (LITE), ii) by gravitational perturbations on the binary orbit, or iii) a combination of the two effects resulting in eclipse timing (ETV) and transit timing (TTV) variations. Motivated by the four recently detected circumbinary planets by the Kepler space telescope (Kepler-16b, Kepler-34b, Kepler-35b and Kepler-38b) we have begun to study their dynamics in the presence of an additional massive perturber. In particular we used Kepler-16b as a test bed case. We are aiming to study the detectability of non-transiting and inclined circumbinary planets using the ETV effect along with the fast indicator MEGNO to quantitatively map the chaotic/quasi-periodic regions of the orbital parameter-space and to determine where the orbit of a circumbinary planet will be stable. We have calculated the amplitudes of TTV and ETV signals for different values of the mass and orbital elements of the planet and binary.
Aspect of Dynamic Simulation and Experimental Research Studies on Hybrid Pneumatic Power System
Directory of Open Access Journals (Sweden)
K. David Huang
2010-01-01
Full Text Available A Hybrid Pneumatic Power System (HPPS has been developed for several years with the major aim of reducing the vehicle fuel consumption, environment pollution and enhancing the vehicle performance as well. Comparing with the conventional hybrid system, HPPS replaces the battery's electrochemical energy with a high-pressure air storage tank and enables the internal combustion engine (ICE to function at its sweet spot. Besides, the HPPS, which effectively merges both the high-pressure air flow from the storage tank and the recycled exhaust flow from the ICE, thereby increases the thermal efficiency of the ICE and transforms the merged flow energy into mechanical energy using a high-efficiency turbine. This paper focuses on the major research process into HPPSs, including overall dynamic simulation and experimental validation. By using the simulation tool ITI-Sim, this research demonstrates an experiment which can be operated precisely according to the requirements of various driving conditions under which a car actually runs on the road in accordance with the regulated running vehicle test mode. HPPS is expected to increase the performance of the entire system from 15% to 39%, and is likely to replace the traditional system in the coming years.
Energy Technology Data Exchange (ETDEWEB)
Shankaran, Harish; Zhang, Yi; Chrisler, William B.; Ewald, Jonathan A.; Wiley, H. S.; Resat, Haluk
2012-10-02
The epidermal growth factor receptor (EGFR) belongs to the ErbB family of receptor tyrosine kinases, and controls a diverse set of cellular responses relevant to development and tumorigenesis. ErbB activation is a complex process involving receptor-ligand binding, receptor dimerization, phosphorylation, and trafficking (internalization, recycling and degradation), which together dictate the spatio-temporal distribution of active receptors within the cell. The ability to predict this distribution, and elucidation of the factors regulating it, would help to establish a mechanistic link between ErbB expression levels and the cellular response. Towards this end, we constructed mathematical models for deconvolving the contributions of receptor dimerization and phosphorylation to EGFR activation, and to examine the dependence of these processes on sub-cellular location. We collected experimental datasets for EGFR activation dynamics in human mammary epithelial cells, with the specific goal of model parameterization, and used the data to estimate parameters for several alternate models. Model-based analysis indicated that: 1) signal termination via receptor dephosphorylation in late endosomes, prior to degradation, is an important component of the response, 2) less than 40% of the receptors in the cell are phosphorylated at any given time, even at saturating ligand doses, and 3) receptor dephosphorylation rates at the cell surface and early endosomes are comparable. We validated the last finding by measuring EGFR dephosphorylation rates at various times following ligand addition both in whole cells, and in endosomes using ELISAs and fluorescent imaging. Overall, our results provide important information on how EGFR phosphorylation levels are regulated within cells. Further, the mathematical model described here can be extended to determine receptor dimer abundances in cells co-expressing various levels of ErbB receptors. This study demonstrates that an iterative cycle of
Dynamic aspects of soil water availability for isohydric plants: Focus on root hydraulic resistances
Couvreur, V.; Vanderborght, J.; Draye, X.; Javaux, M.
2014-11-01
Soil water availability for plant transpiration is a key concept in agronomy. The objective of this study is to revisit this concept and discuss how it may be affected by processes locally influencing root hydraulic properties. A physical limitation to soil water availability in terms of maximal flow rate available to plant leaves (Qavail) is defined. It is expressed for isohydric plants, in terms of plant-centered variables and properties (the equivalent soil water potential sensed by the plant, ψs eq; the root system equivalent conductance, Krs; and a threshold leaf water potential, ψleaf lim). The resulting limitation to plant transpiration is compared to commonly used empirical stress functions. Similarities suggest that the slope of empirical functions might correspond to the ratio of Krs to the plant potential transpiration rate. The sensitivity of Qavail to local changes of root hydraulic conductances in response to soil matric potential is investigated using model simulations. A decrease of radial conductances when the soil dries induces earlier water stress, but allows maintaining higher night plant water potentials and higher Qavail during the last week of a simulated 1 month drought. In opposition, an increase of radial conductances during soil drying provokes an increase of hydraulic redistribution and Qavail at short term. This study offers a first insight on the effect of dynamic local root hydraulic properties on soil water availability. By better understanding complex interactions between hydraulic processes involved in soil-plant hydrodynamics, better prospects on how root hydraulic traits mitigate plant water stress might be achieved.
Dynamic and kinetic aspects of the adsorption of acrylonitrile on Si(001)-2x1
International Nuclear Information System (INIS)
Using scanning tunnelling microscopy (STM), photoelectron and photoabsorption spectroscopies, we have examined how acrylonitrile (H2C=CH-C≡N) reacts with the Si(001)-2x1 surface for coverages ranging from ∼1012 molecules/cm2 to ∼1014 molecules/cm2. At 300 K, in the very low coverage regime (below 1013 molecules/cm2), filled- and empty-state STM images show that the molecule bridges, via its β carbon and nitrogen ends, two silicon dangling bonds, across the trench separating two dimer rows. A cumulative-double-bond unit (C=C=N) is formed. The 300 K STM image results from the dynamic flipping of the molecule between two equivalent equilibrium positions, which can be seen when the molecular motion is slowed down at 80 K. For coverages larger than 1013 molecules/cm2, for which STM does not show ordered adsorption any more, the adsorption kinetics were observed in real-time using valence band photoemission and resonant Auger yield, associated with N 1s x-ray absorption spectroscopy (NEXAFS). At 300 K, these techniques point to a situation more complex than the one explored by STM at very low coverage. Three species (cyano-bonded, vinyl-bonded, and cumulative-double-bond species) are detected. Their distribution does not vary with increasing coverage. All dimerization-related surface states are quenched at saturation. The uptake rates versus coverage relationship points to the presence of a mobile precursor. Finally, the paper discusses a possible mechanism leading to the formation of cross-trench C=C=N unit at low coverage, and the reasons why the product branching ratio changes with increasing coverage
Directory of Open Access Journals (Sweden)
M. Sanbi
2014-01-01
Full Text Available Smart structures with integrated sensors, actuators, and control electronics are of importance to the next generation high-performance structural systems. In this study, thermopiezoelastic characteristics of piezoelectric beam continua are studied and applications of the theory to active structures in sensing and optimal control are discussed. Using linear thermopiezoelastic theory and Timoshenko assumptions, a generic thermopiezoelastic theory for piezolaminated composite beam is derived. Finite element equations for the thermopiezoelastic media are obtained by using the linear constitutive equations in Hamilton's principle together with the finite element approximations. The structure consists of a modeling of cantilevered piezolaminated Timoshenko beam with integrated thermopiezoelectric elements between two aluminium layers. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG accompanied by the Kalman filter is applied. The effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. We show that the control procedure cannot be perturbed by applying a thermal gradient and the control can be applied at any time during the period of vibration of the beam.
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.
Non-Linear Time-Domain Simulations of the RF Station-Beam Dynamics Interaction for the LHC
International Nuclear Information System (INIS)
Non-linear time-domain simulations have been developed for the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC). These simulations capture the dynamic behavior of the RF station-beam interaction and are structured to reproduce the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They are also a valuable tool for the study of diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Results from these studies and related measurements from PEP-II and LHC have been presented in multiple places. This report presents an example of the time-domain simulation implementation for the LHC.
Dynamic photorefractive self-amplified angular-multiplex 2-D optical beam-array generation
Zhou, Shaomin; Yeh, Pochi; Liu, Hua-Kuang
1993-01-01
A real-time 2-D angular-multiplex beam-array holographic storage and reconstruction technique using electrically-addressed spatial light modulators(E-SLM's) and photorefractive crystals is described. Using a liquid crystal television (LCTV) spatial light modulator (SLM) for beam steering and lithium niobate photorefractive crystal for holographic recording, experimental results of generating large and complicated arrays of laser beams with high diffraction efficiency and good uniformity are presented.
Golubev, Vladimir S.; Banishev, Alexander F.; Azharonok, V. V.; Zabelin, Alexandre M.
1994-09-01
A qualitative analysis of the role of some hydrodynamic flows and instabilities by the process of laser beam-metal sample deep penetration interaction is presented. The forces of vapor pressure, melt surface tension and thermocapillary forces can determined a number of oscillatory and nonstationary phenomena in keyhole and weld pool. Dynamics of keyhole formation in metal plates has been studied under laser beam pulse effect ((lambda) equals 1.06 micrometers ). Velocities of the keyhole bottom motion have been determined at 0.5 X 105 - 106 W/cm2 laser power densities. Oscillatory regime of plate break- down has been found out. Small-dimensional structures with d-(lambda) period was found on the frozen cavity walls, which, in our opinion, can contribute significantly to laser beam absorption. A new form of periodic structure on the frozen pattern being a helix-shaped modulation of the keyhole walls and bottom relief has been revealed. Temperature oscillations related to capillary oscillations in the melt layer were discovered in the cavity. Interaction of the CW CO2 laser beam and the matter by beam penetration into a moving metal sample has been studied. The pulsed and thermodynamic parameters of the surface plasma were investigated by optical and spectroscopic methods. The frequencies of plasma jets pulsations (in 10 - 105 Hz range) are related to possible melt surface instabilities of the keyhole.
Energy Technology Data Exchange (ETDEWEB)
Friedman, A; Barnard, J J; Cohen, R H; Grote, D P; Lund, S M; Sharp, W M; Faltens, A; Henestroza, E; Jung, J; Kwan, J W; Lee, E P; Leitner, M A; Logan, B G; Vay, J; Waldron, W L; Davidson, R C; Dorf, M; Gilson, E P; Kaganovich, I
2009-11-19
Intense beams of heavy ions are well suited for heating matter to regimes of emerging interest. A new facility, NDCX-II, will enable studies of warm dense matter at {approx}1 eV and near-solid density, and of heavy-ion inertial fusion target physics relevant to electric power production. For these applications the beam must deposit its energy rapidly, before the target can expand significantly. To form such pulses, ion beams are temporally compressed in neutralizing plasma; current amplification factors of {approx}50-100 are routinely obtained on the Neutralized Drift Compression Experiment (NDCX) at LBNL. In the NDCX-II physics design, an initial non-neutralized compression renders the pulse short enough that existing high-voltage pulsed power can be employed. This compression is first halted and then reversed by the beam's longitudinal space-charge field. Downstream induction cells provide acceleration and impose the head-to-tail velocity gradient that leads to the final neutralized compression onto the target. This paper describes the discrete-particle simulation models (1-D, 2-D, and 3-D) employed and the space-charge-dominated beam dynamics being realized.
Energy Technology Data Exchange (ETDEWEB)
Friedman, A.; Barnard, J.J.; Cohen, R.H.; Grote, D.P.; Lund, S.M.; Sharp, W.M.; Faltens, A.; Henestroza, E.; Jung, J.-Y.; Kwan, J.W.; Lee, E.P.; Leitner, M.A.; Logan, B.G.; Vay, J.-L.; Waldron, W.L.; Davidson, R.C.; Dorf, M.; Gilson, E.P.; Kaganovich, I.D.
2009-12-19
Intense beams of heavy ions are well suited for heating matter to regimes of emerging interest. A new facility, NDCX-II, will enable studies of warm dense matter at {approx}1 eV and near-solid density, and of heavy-ion inertial fusion target physics relevant to electric power production. For these applications the beam must deposit its energy rapidly, before the target can expand significantly. To form such pulses, ion beams are temporally compressed in neutralizing plasma; current amplification factors of {approx}50-100 are routinely obtained on the Neutralized Drift Compression Experiment (NDCX) at LBNL. In the NDCX-II physics design, an initial non-neutralized compression renders the pulse short enough that existing high-voltage pulsed power can be employed. This compression is first halted and then reversed by the beam's longitudinal space-charge field. Downstream induction cells provide acceleration and impose the head-to-tail velocity gradient that leads to the final neutralized compression onto the target. This paper describes the discrete-particle simulation models (1-D, 2-D, and 3-D) employed and the space-charge-dominated beam dynamics being realized.
International Nuclear Information System (INIS)
Superconducting magnets of large size are inevitable for fusion devices due to high magnetic field requirements. Forced flow cooling of the superconducting magnets with high mass flowrate of the order ∼3 kg/s is required to keep superconducting magnets within its safe operational boundaries during various plasma scenarios. This important requirement can be efficiently fulfilled by employing high capacity and high efficiency cryogenic centrifugal pumps. The efficiency > 70% will ensure overall lower heat load to the cryoplant. Thermo-hydraulic design of cryogenic centrifugal pump revealed that to achieve the operational regime with high efficiency, the speed should be ∼ 10,000 revolutions per minute. In this regard, the rotor-dynamic design aspect is quite critical from the operational stability point of view. The rotor shaft design of the cryogenic pump is primarily an outcome of optimization between thermal heat-in leak at cryogenic temperature level from ambient, cryogenic fluid impedance and designed rotation speed of the impeller wheel. The paper describes the basic design related to critical speed of the rotor shaft, rotor whirl and system instability prediction to explore the ideal operational range of the pump from the system stability point of view. In the rotor-dynamic analysis, the paper also describes the Campbell plots to ensure that the pump is not disturbed by any of the critical speeds, especially while operating near the nominal and enhanced operating modes. (author)
Lin, C Y; Jones, A; Woodraska, D; Caspi, A; Woods, T N; Eparvier, F G; Wieman, S R; Didkovsky, L V
2016-01-01
The Solar Aspect Monitor (SAM) is a pinhole camera on the Extreme-ultraviolet Variability Experiment (EVE) aboard the Solar Dynamics Observatory (SDO). SAM projects the solar disk onto the CCD through a metallic filter designed to allow only solar photons shortward of 7 nm to pass. Contamination from energetic particles and out-of-band irradiance is, however, significant in the SAM observations. We present a technique for isolating the 0.01--7 nm integrated irradiance from the SAM signal to produce the first results of broadband irradiance for the time period from May 2010 to May 2014. The results of this analysis agree with a similar data product from EVE's EUV SpectroPhotometer (ESP) to within 25%. We compare our results with measurements from the Student Nitric Oxide Explorer (SNOE) Solar X-ray Photometer (SXP) and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) Solar EUV Experiment (SEE) at similar levels of solar activity. We show that the full-disk SAM broadband results compare we...
Developing models for simulation of pinched-beam dynamics in heavy ion fusion. Revision 1
International Nuclear Information System (INIS)
For heavy-ion fusion energy applications, Mark and Yu have derived hydrodynamic models for numerical simulation of energetic pinched-beams including self-pinches and external-current pinches. These pinched-beams are applicable to beam propagation in fusion chambers and to the US High Temperature Experiment. The closure of the Mark-Yu model is obtained with adiabatic assumptions mathematically analogous to those of Chew, Goldberger, and Low for MHD. Features of this hydrodynamic beam model are compared with a kinetic treatment
Pump-probe imaging of the fs-ps-ns dynamics during femtosecond laser Bessel beam drilling in PMMA.
Yu, Yanwu; Jiang, Lan; Cao, Qiang; Xia, Bo; Wang, Qingsong; Lu, Yongfeng
2015-12-14
A pump-probe shadowgraph imaging technique was used to reveal the femtosecond-picosecond-nanosecond multitimescale fundamentals of high-quality, high-aspect-ratio (up to 287:1) microhole drilling in poly-methyl-meth-acrylate (PMMA) by a single-shot femtosecond laser Bessel beam. The propagation of Bessel beam in PMMA (at 1.98 × 10⁸ m/s) and it induced cylindrical pressure wave expansion (at 3000-3950 m/s in radius) were observed during drilling processes. Also, it was unexpectedly found that the expansion of the cylindrical pressure wave in PMMA showed a linear relation with time and was insensitive to the laser energy fluctuation, quite different from the case in air. It was assumed that the energy insensitivity was due to the anisotropy of wave expansion in PMMA and the ambient air. PMID:26699062
Pump-probe imaging of the fs-ps-ns dynamics during femtosecond laser Bessel beam drilling in PMMA.
Yu, Yanwu; Jiang, Lan; Cao, Qiang; Xia, Bo; Wang, Qingsong; Lu, Yongfeng
2015-12-14
A pump-probe shadowgraph imaging technique was used to reveal the femtosecond-picosecond-nanosecond multitimescale fundamentals of high-quality, high-aspect-ratio (up to 287:1) microhole drilling in poly-methyl-meth-acrylate (PMMA) by a single-shot femtosecond laser Bessel beam. The propagation of Bessel beam in PMMA (at 1.98 × 10⁸ m/s) and it induced cylindrical pressure wave expansion (at 3000-3950 m/s in radius) were observed during drilling processes. Also, it was unexpectedly found that the expansion of the cylindrical pressure wave in PMMA showed a linear relation with time and was insensitive to the laser energy fluctuation, quite different from the case in air. It was assumed that the energy insensitivity was due to the anisotropy of wave expansion in PMMA and the ambient air.
Statistical signal processing techniques for coherent transversal beam dynamics in synchrotrons
Energy Technology Data Exchange (ETDEWEB)
Alhumaidi, Mouhammad
2015-03-04
Transversal coherent beam oscillations can occur in synchrotrons directly after injection due to errors in position and angle, which stem from inaccurate injection kicker reactions. Furthermore, the demand for higher beam intensities is always increasing in particle accelerators. The wake fields generated by the traveling particles will be increased by increasing the beam intensity. This leads to a stronger interaction between the beam and the different accelerator components, which increases the potential of coherent instabilities. Thus, undesired beam oscillations will occur when the natural damping is not enough to attenuate the oscillations generated by the coherent beam-accelerator interactions. The instabilities and oscillations can be either in transversal or longitudinal direction. In this work we are concerned with transversal beam oscillations only. In normal operation, transversal beam oscillations are undesired since they lead to beam quality deterioration and emittance blow up caused by the decoherence of the oscillating beam. This decoherence is caused by the tune spread of the beam particles. The emittance blow up reduces the luminosity of the beam, and thus the collision quality. Therefore, beam oscillations must be suppressed in order to maintain high beam quality during acceleration. A powerful way to mitigate coherent instabilities is to employ a feedback system. A Transversal Feedback System (TFS) senses instabilities of the beam by means of Pickups (PUs), and acts back on the beam through actuators, called kickers. In this thesis, a novel concept to use multiple PUs for estimating the beam displacement at the position with 90 phase advance before the kicker is proposed. The estimated values should be the driving feedback signal. The signals from the different PUs are delayed such that they correspond to the same bunch. Subsequently, a weighted sum of the delayed signals is suggested as an estimator of the feedback correction signal. The
Energy Technology Data Exchange (ETDEWEB)
Raith, J. [Universitaetsklinik fuer Radiologie, Graz (Austria); Lindbichler, F. [Universitaetsklinik fuer Radiologie, Graz (Austria); Kern, R. [Universitaetsklinik fuer Radiologie, Graz (Austria); Groell, R. [Universitaetsklinik fuer Radiologie, Graz (Austria); Rienmueller, R. [Universitaetsklinik fuer Radiologie, Graz (Austria)
1996-03-01
Three cases preselected by videofluorography were studied to evaluate whether electron beam tomography (EBT) permits more detailed dynamic imaging of swallowing disorders focusing on the mesonasopharyngeal segment, the hypopharynx and the upper esophageal sphincter (UES). Immediately after videofluorographic examination of the oropharyngeal deglutition, EBT is performed. The patient is in a supine position and while the patient swallows a 20 ml bolus of water or diluted iodine containing contrast agent, a sequence of 20 images per level is scanned. The levels, which are determined by using the scout view, are oriented parallel to the hard palate either at the level of the hard palate to image the mesonasopharyngel segment or just above the hyoid bone to focus on the hypopharynx or at the location of the USE. The scan technique is a single-slice cinemode with a slice thickness of 3 mm (exposure time 100 ms, interscan delay 16 ms, 130 kV, 620 mA). The following structural interactions that we have so far been unable to image can be clearly demonstrated with EBT: During normal swallowing, the mesonasopharyngeal segment is completely and symmetrically closed by the soft palate and Passavant`s cushion; lateral hypopharyngeal pouches can be located more precisely; and disorders of the UES can be differentiated into functional or morphologically caused disorders (e.g., goiter or cervical osteophytes). Videofluorography and cinematography are still the gold standard in functional evaluation of swallowing disorders. However, EBT permits dynamic imaging of pharyngeal deglutition in a preselected transverse plane and can give useful additional information concerning functional anatomical changes in the pharynx during swallowing. Further clinical evaluation is needed. (orig.) [Deutsch] Videofluorographie und Kinematographie gelten derzeit als Goldstandard fuer die Abklaerung von Schluckstoerungen. Methodisch bedingt ist jedoch keine ueberlagerungsfreie Darstellung der
Institute of Scientific and Technical Information of China (English)
YangJialing; LiuXuhong
2004-01-01
The rigid, perfectly plastic dynamic response of a free-free beam subjected to impact by a projectile at any cross-section is studied. The instantaneous deformations of the beam are given through an analysis of the complete solution for rigid plastic structures. The influence of some parameters such as the input energy and mass ratio on the plastic deformation, travelling plastic hinge position and energy partitioning of the beam are discussed.
Nonlinear Dynamic Analysis of Functionally Graded Timoshenko Beam fixed to a Rotating Hub
Panigrahi, B.; Pohit, G.
2016-08-01
The present work accounts centrifugal stiffening effect on the nonlinear vibration response of an FGM Timoshenko beam. Analysis is carried out for a cantilever beam fixed with a rotating hub. Material is assumed to have a gradation relation along the depth of the beam. Centrifugal force and axial displacement raised due to the rotating hub is incorporated in the strain energy equations. Subsequent to this, an iterative technique is employed to obtain amplitude dependent vibration response of a rotating Timoshenko beam while material follows a gradation relation along the beam depth. Main objective of the work is to obtain the effects of rotational speeds, hub radius, and different gradation relations on the linear as well as nonlinear frequencies and mode shapes.
Simulating Transient Effects of Pulsed Beams on Beam Intercepting Devices
Richter, Herta; Noah Messomo, Etam
2011-01-01
The development in the physics community towards higher beam power through the possibilities of particle accelerators lead to challenges for the developers of elements which are exposed to effect of particle beams (beam intercepting devices = BIDs). For the design of BIDs, the increasing heat load onto these devices due to energetic and focused beams and - in most cases - their highly pulsed nature has to be taken into account. The physics requirements are sometimes opposed to the current state of the art. As one possibility of many in combining the different aspects for these ambitious demands, two highly developed computer programs, namely FLUKA and ANSYS AUTODYN, were joined for this dissertation. The former is a widely enhanced Monte-Carlo-code which specializes on the interaction of particles with static matter, while the latter is a versatile explicit code for the simulation of highly dynamic processes. Both computer programs were developed intensively over years and are still continuously enhanced in o...
High dynamic range diamond detector acquisition system for beam wire scanner applications
International Nuclear Information System (INIS)
The CERN Beam Instrumentation group has been working during the last years on the beam wire scanners upgrade to cope up with the increasing requirements of CERN experiments. These devices are used to measure the beam profile by crossing a thin wire through a circulating beam, the resulting secondary particles produced from beam/wire interaction are detected and correlated with the wire position to reconstruct the beam profile. The upgraded secondary particles acquisition electronics will use polycrystalline chemical vapour deposition (pCVD) diamond detectors for particle shower measurements, with low noise acquisitions performed on the tunnel, near the detector. The digital data is transmitted to the surface through an optical link with the GBT protocol. Two integrator ASICs (ICECAL and QIE10) are being characterized and compared for detector readout with the complete acquisition chain prototype. This contribution presents the project status, the QIE10 front-end performance and the first measurements with the complete acquisition system prototype. In addition, diamond detector signals from particle showers generated by an operational beam wire scanner are analysed and compared with an operational system
Energy Technology Data Exchange (ETDEWEB)
Blank, D.A.
1997-08-01
This dissertation describes the use of a new molecular beam apparatus designed to use tunable VUV synchrotron radiation for photoionization of the products from scattering experiments. The apparatus was built at the recently constructed Advanced Light Source at Lawrence Berkeley National Laboratory, a third generation 1-2 GeV synchrotron radiation source. The new apparatus is applied to investigations of the dynamics of unimolecular reactions, photodissociation experiments, and bimolecular reactions, crossed molecular beam experiments. The first chapter describes the new apparatus and the VUV radiation used for photoionization. This is followed by a number of examples of the many advantages provided by using VUV photoionization in comparison with the traditional technique of electron bombardment ionization. At the end of the chapter there is a discussion of the data analysis employed in these scattering experiments. The remaining four chapters are complete investigations of the dynamics of four chemical systems using the new apparatus and provide numerous additional examples of the advantages provided by VUV photoionizaiton of the products. Chapters 2-4 are photofragment translational spectroscopy studies of the photodissociation dynamics of dimethyl sulfoxide, acrylonitrile, and vinyl chloride following absorption at 193 mn. All of these systems have multiple dissociation channels and provide good examples of the ability of the new apparatus to unravel the complex UV photodissociation dynamics that can arise in small polyatomic molecules.
Nam-Il, Kim; Moon-Young, Kim
2005-06-01
An improved numerical method to exactly evaluate the dynamic element stiffness matrix is proposed for the spatially coupled free vibration analysis of non-symmetric thin-walled curved beams subjected to uniform axial force. For this purpose, firstly equations of motion, boundary conditions and force-deformation relations are rigorously derived from the total potential energy for a curved beam element. Next systems of linear algebraic equations with non-symmetric matrices are constructed by introducing 14 displacement parameters and transforming the fourth-order simultaneous differential equations into the first-order simultaneous equations. And then explicit expressions for displacement parameters are numerically evaluated via eigensolutions and the exact 14×14 element stiffness matrix is determined using force-deformation relations. In order to demonstrate the validity and the accuracy of this study, the spatially coupled natural frequencies of non-symmetric thin-walled curved beams subjected to uniform compressive and tensile forces are evaluated and compared with analytical and finite element solutions using Hermitian curved beam elements or ABAQUS's shell element. In addition, some results by the parametric study are reported.
Energy Technology Data Exchange (ETDEWEB)
Kim, Hojin; Strachan, Alejandro [School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)
2015-11-28
We use large-scale molecular dynamics (MD) to characterize fluid damping between a substrate and an approaching beam. We focus on the near contact regime where squeeze film (where fluid gap is comparable to the mean free path of the gas molecules) and many-body effects in the fluid become dominant. The MD simulations provide explicit description of many-body and non-equilibrium processes in the fluid as well as the surface topography. We study how surface roughness and beam width increases the damping coefficient due to their effect on fluid mobility. We find that the explicit simulations are in good agreement with prior direct simulation Monte Carlo results except at near-contact conditions where many-body effects in the compressed fluid lead the increased damping and weaker dependence on beam width. We also show that velocity distributions near the beam edges and for short gaps deviate from the Boltzmann distribution indicating a degree of local non-equilibrium. These results will be useful to parameterize compact models used for microsystem device-level simulations and provide insight into mesoscale simulations of near-contact damping.
Beam dynamics simulations for Gaussian and flat-top laser pulses at PITZ
International Nuclear Information System (INIS)
The Photo Injector Test Facility at DESY, Zeuthen site (PITZ), has been built in order to develop and optimize electron sources for Free Electron Lasers (FELs) like FLASH and the European XFEL. The electron beam is generated by photoemission initiated with a laser pulse having a flat-top temporal profile. Compared to the Gaussian one, such a flat-top profile yields smaller transverse projected emittance. In order to estimate the difference between the two cases, systematic simulations for 500 pC bunch charge are presented. Dependences of electron beam properties, like beam momentum, transverse beam size, phase space, emittance, on various machine parameters, e.g. gun phase, solenoid current, are shown as well.
Study of Acquisition Electronics with a High Dynamic Range for a Beam Loss Measurement System
Venturini, G; Dehning, B; Effinger, E
2010-01-01
The particles accelerated in CERN accelerator chain reach high energies, topped by the particle energy at collision in the LHC, 7 GeV. During the operation, an amount of particles is inevitably lost from the beam. Depending on the extent of the losses, physical damage to machine components may be caused and the shower of secondary emission particles deposits energy in the surrounding equipment constituting the accelerator. The hadronic cascade also activates their materials, representing a hazard to the workers at CERN. In the LHC, the superconducting magnets that constitute the synchrotron lattice are kept at an operating temperature of 1:9K through a cryogenic facility employing superliquid helium, the increase in their temperature potentially initiates a quench. In the SPS, the damage due to a lost beam is also visible. The Beam Loss Monitoring (BLM) system has been developed to reliably protect the machines composing CERN’s accelerator chain and additionally provide information about the beam status: th...
Dynamic axial stabilization of counterpropagating beam-traps with feedback control
DEFF Research Database (Denmark)
Tauro, Sandeep; Bañas, Andrew Rafael; Palima, Darwin;
2010-01-01
Optical trapping in a counter-propagating (CP) beam-geometry provides unique advantages in terms of working distance, aberration requirements and intensity hotspots. However, its axial performance is governed by the wave propagation of the opposing beams, which can limit the practical geometries....... Advanced implementation of this feedback-driven approach can help make CP-trapping resistant to a host of perturbations such as laser fluctuations, mechanical vibrations and other distortions emphasizing its experimental versatility....
Transverse beam dynamics in recirculating accelerators for heavy-ion fusion
International Nuclear Information System (INIS)
A conceptual design for a circular induction accelerator has been proposed as a driver for heavy-ion fusion. In such an accelerator, errors in dipole strength and quadrupole alignment affect the transverse motion of the beam centroid. Analytic and numerical estimates are made of the beam-centroid displacement due to these errors, and a steering algorithm to correct the transverse mismatch from these errors is described and tested numerically
Lifescience Database Archive (English)
Full Text Available 12005202 Molecular aspects of anti-inflammatory action of G-CSF. Boneberg EM, Hartu...ng T. Inflamm Res. 2002 Mar;51(3):119-28. (.png) (.svg) (.html) (.csml) Show Molecular aspects of anti-infla...mmatory action of G-CSF. PubmedID 12005202 Title Molecular aspects of anti-inflammatory action of G-CSF. Aut
Reaction dynamics induced by the radioactive ion beam {sup 7}Be on medium-mass and heavy targets
Energy Technology Data Exchange (ETDEWEB)
Mazzocco, M., E-mail: marco.mazzocco@pd.infn.it; Stefanini, C.; Strano, E.; Torresi, D.; Lay, J. A.; Molini, P.; Soramel, F. [Dipartimento di Fisica e Astronomia, Università di Padova, via F. Marzolo 8, I-35131 Padova (Italy); INFN-Sezione di Padova, via F. Marzolo 8, I-35131 Padova (Italy); Boiano, A.; Parascandolo, C.; Pierroutsakou, D.; Di Meo, P. [INFN-Sezione di Napoli, via Cintia, I-80126, Napoli (Italy); Boiano, C. [INFN-Sezione di Milano, via Celoria 16, I-20133, Napoli (Italy); La Commara, M.; Sandoli, M.; Silvestri, R. [INFN-Sezione di Napoli, via Cintia, I-80126, Napoli (Italy); Dipartimento di Fisica, Università di Napoli “Federico II”, via Cintia, I-80126, Napoli (Italy); Manea, C.; Nicoletto, M. [INFN-Sezione di Padova, via F. Marzolo 8, I-35131 Padova (Italy); Acosta, L. [Departamento de Fìsica Aplicada, Universidad de Huelva, Campus de El Carmen, E-21071 Huelva (Spain); INFN-Sezione di Catania, via Santa Sofia 64, I-95123, Catania (Italy); Fernandez-Garcia, J. P. [INFN-Sezione di Catania, via Santa Sofia 64, I-95123, Catania (Italy); Glodariu, T. [National Institute for Physics and Nuclear Engineering (NIPNE), 30 Reactorului St., 077125 Magurele (Romania); and others
2015-10-15
We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam {sup 7}Be (S{sub α} = 1.586 MeV) on medium-mass ({sup 58}Ni) and heavy ({sup 208}Pb) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3×10{sup 5} pps {sup 7}Be secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems.
Instrumentation and Beam Dynamics Study of Advanced Electron-Photon Facility in Indiana University
Energy Technology Data Exchange (ETDEWEB)
Luo, Tianhuan [Indiana Univ., Bloomington, IN (United States)
2011-08-01
The Advanced eLectron-PHoton fAcility (ALPHA) is a compact electron accelerator under construction and being commissioned at the Indiana University Center for Exploration of Energy and Matter (CEEM). In this thesis, we have studied the refurbished Cooler Injector Synchrotron (CIS) RF cavity using both the transmission line model and SUPERFISH simulation. Both low power and high power RF measurements have been carried out to characterize the cavity. Considering the performance limit of ferrite, we have designed a new ferrite loaded, co-axial quarter wave like cavity with similar structure but a more suitable ferrite material. We have also designed a traveling wave stripline kicker for fast extraction by POISSON and Microwave Studio. The strips geometry is trimmed to maximize the uniformity of the kicking field and match the impedance of the power cables. The time response simulation shows the kicker is fast enough for machine operation. The pulsed power supply requirement has also been specified. For the beam diagnosis in the longitudinal direction, we use a wideband Wall Gap Monitor (WGM) served in CIS. With proper shielding and amplification to get good WGM signal, we have characterized the injected and extracted beam signal in single pass commissioning, and also verified the debunching effect of the ALPHA storage ring. A modulation-demodulation signal processing method is developed to measure the current and longitudinal profile of injected beam. By scanning the dipole strength in the injection line, we have reconstructed the tomography of the longitudinal phase space of the LINAC beam. In the accumulation mode, ALPHA will be operated under a low energy and high current condition, where intra beam scattering (IBS) becomes a dominant effect on the beam emittance. A self consistent simulation, including IBS effect, gas scattering and linear coupling, has been carried out to calculate the emittance of the stored beam.
Energy Technology Data Exchange (ETDEWEB)
Chu, P.M.Y.
1991-10-01
The vibrational to translational (V{yields}T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V{yields}T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH{sub 3} production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam.
The thickness-dependent dynamic magnetic property of Co2FeAl films grown by molecular beam epitaxy
Qiao, Shuang; Nie, Shuaihua; Zhao, Jianhua; Zhang, Xinhui
2014-10-01
Co2FeAl films with different thickness were prepared at different temperature by molecular beam epitaxy. Their dynamic magnetic property was studied by the time-resolved magneto-optical Kerr effect measurements. It is observed that the intrinsic damping factor of Co2FeAl for [100] orientation is not related to the film's thickness and magnetic anisotropy as well as temperature at high-field regime, but increases with structural disorder of Co2FeAl. The dominant contribution from the inhomogeneous magnetic anisotropy is revealed to be responsible for the observed extremely nonlinear and drastic field-dependent damping factors at low-field regime.
Giovannozzi, M; Høimyr, N; Jones, PL; Karneyeu, A; Marquina, MA; McIntosh, E; Segal, B; Skands, P; Grey, F; Lombraña González, D; Rivkin, L; Zacharov, I
2012-01-01
Recently, the LHC@home system has been revived at CERN. It is a volunteer computing system based on BOINC which boosts the available CPU-power in institutional computer centres with the help of individuals that donate the CPU-time of their PCs. Currently two projects are hosted on the system, namely SixTrack and Test4Theory. The first is aimed at performing beam dynamics simulations, while the latter deals with the simulation of high-energy events. In this paper the details of the global system, as well a discussion of the capabilities of each project will be presented.
Beam dynamics and wakefield suppression in interleaved damped and detuned structures for CLIC
D'Elia, A; Khan, V F; Jones, R M; Latina, A; Nesmiyan, I; Riddone, G
2013-01-01
Acceleration of multiple bunches of charged particles in the main linacs of the Compact Linear Collider (CLIC) with high accelerating fields provides two major challenges: firstly, to ensure the surface electromagnetic fields do not cause electrical breakdown and subsequent surface damage, and secondly, to ensure the beam-excited wakefields are sufficiently suppressed to avoid appreciable emittance dilution. In the baseline design for CLIC, heavy wakefield suppression is used (Q ~ 10) [1] and this ensures the beam quality is well-preserved [2]. Here we discuss an alternative means to suppress the wakefield which relies on strong detuning of the cell dipole frequencies, together with moderate damping, effected by manifolds which are slot-coupled to each accelerating cell. This damped and detuned wakefield suppression scheme is based on the methodology developed for the Japanese Linear Collider/Next Linear Collider (JLC/NLC) [3]. Here we track the multi-bunch beam down the complete collider, u...
Study of filamentation dynamics of ultrashort laser radiation in air: beam diameter effect
International Nuclear Information System (INIS)
A single filamentation of femtosecond gigawatt laser radiation with a millimeter-size aperture upon collimated and sharply focused propagation in atmospheric air at 800 nm and 400 nm wavelengths is studied both theoretically and experimentally. The influence of beam initial radius on the parameters of the forming filament is analyzed. Three filament parameters, namely, start coordinate, filament length, and longitudinal continuity are considered. We report that unlike Marburger’s formula the single filamentation onset reveals marked nonquadratic dependence on the laser beam radius providing the same initial pulse power. Additionally, for sharply focused radiation the minor dependence of the filament length on the laser beam diameter at the constant initial pulse intensity was experimentally revealed. (paper)
Speckle dynamics for dual-beam optical illumination of a rotating structure
DEFF Research Database (Denmark)
Jakobsen, Michael Linde; Yura, Harold; Hanson, Steen Grüner
2009-01-01
Fourier transform system. It is shown that the compound speckle structures move as two individual structures with the same decorrelation length. The velocity of the random speckles is a combination of angular and peripheral velocity, where the peripheral velocity is inversely proportional to the radius of...... the wavefront curvature of the incident beams. The velocity of the repetitive structure is a combination of angular and peripheral velocity, where the peripheral velocity is proportional to the ratio of the angle to the distance between the beams in the object plane. Experimental data demonstrate good...... speckles modulated by a smaller and repetitive structure. Generally, these two components of the compound speckle structure will move as rigid structures with individual velocities determined by the characteristics of the two illuminating beams. Closed-form analytical expressions are found for the space...
Fast Calculation Methods in Collective Dynamical Models of Beam/Plasma Physics
Fedorova, A N; Fedorova, Antonina N.; Zeitlin, Michael G.
2002-01-01
We consider an application of modification of our variational-wavelet approach to some nonlinear collective model of beam/plasma physics: Vlasov/Boltzmann-like reduction from general BBGKY hierachy related to modeling of propagation of intense charged particle beams in high-intensity accelerators and transport systems. We use fast convergent multiscale variational-wavelet representations for solutions which allow to consider polynomial and rational type of nonlinearities. The solutions are represented via the multiscale decomposition in nonlinear high-localized eigenmodes (waveletons). In contrast with different approaches we do not use perturbation technique or linearization procedures.
Beam dynamics in an initial part of a high Brightness electron linac
Ayzatsky, M I; Dovbnya-Kushnir, V A
2001-01-01
The paper is focused on problems of obtained a bright electron beam in a system that includes a grid-controlled electron gun,a klystron type type subharmonical buncher, a standing wave fundamental buncher with increasing accelerating field and a short travelling wave accelerating section. Beam focusing is provided by a longitudinal solenoidal magnetic field.It was shown that the proposed system can provide electron bunches with a peak current more than 100 A and normalized r.m.s. emittance no more than phi centre dot mm centre dot mrad.
Instability and dynamics of two nonlinearly coupled laser beams in a plasma
Shukla, P K; Marklund, M; Stenflo, L; Kourakis, I; Parviainen, M; Dieckmann, M E
2006-01-01
We investigate the nonlinear interaction between two laser beams in a plasma in the weakly nonlinear and relativistic regime. The evolution of the laser beams is governed by two nonlinear Schroedinger equations that are coupled with the slow plasma density response. We study the growth rates of the Raman forward and backward scattering instabilities as well of the Brillouin and self-focusing/modulational instabilities. The nonlinear evolution of the instabilities is investigated by means of direct simulations of the time-dependent system of nonlinear equations.
Extending the Nonlinear-Beam-Dynamics Concept of 1D Fixed Points to 2D Fixed Lines
Franchetti, G.
2015-01-01
The origin of nonlinear dynamics traces back to the study of the dynamics of planets with the seminal work of Poincaré at the end of the nineteenth century: Les Méthodes Nouvelles de la Mécanique Céleste, Vols. 1–3 (Gauthier Villars, Paris, 1899). In his work he introduced a methodology fruitful for investigating the dynamical properties of complex systems, which led to the so-called “Poincaré surface of section,” which allows one to capture the global dynamical properties of a system, characterized by fixed points and separatrices with respect to regular and chaotic motion. For two-dimensional phase space (one degree of freedom) this approach has been extremely useful and applied to particle accelerators for controlling their beam dynamics as of the second half of the twentieth century.We describe here an extension of the concept of 1D fixed points to fixed lines in two dimensions. These structures become the fundamental entities for characterizing the nonlinear motion in the four-dimensional phas...
International Nuclear Information System (INIS)
An S-band (2856 MHz) 5 MeV, 3 kW traveling wave linear accelerator is currently under design and development at Raja Ramanna Centre for Advanced Technology, Indore. The accelerating structure is a 2π/3 mode constant impedance traveling wave structure, designed to accelerates the 50 keV electron beam from the electron gun to 5 MeV. It comprises of traveling wave buncher cells followed by regular accelerating cells. This paper presents the details of electromagnetic design simulations to fix the mechanical dimensions and tolerances, as well as heat loss calculations in the structure. Comparison of the results obtained from detailed numerical simulations with those obtained from approximate analytical calculations is described in the paper. The beam dynamics simulation from beginning to end of the linac is also performed and the required magnetic field profile for keeping the beam focused in the linac has been evaluated. The aim has been to maximize the capture efficiency with reduced energy spread in a short and compact structure. (author)
Dynamics of cavitation clouds within a high-intensity focused ultrasonic beam
Lu, Yuan; Katz, Joseph; Prosperetti, Andrea
2013-01-01
In this experimental study, we generate a 500 kHz high-intensity focused ultrasonic beam, with pressure amplitude in the focal zone of up to 1.9 MPa, in initially quiescent water. The resulting pressure field and behavior of the cavitation bubbles are measured using high-speed digital in-line hologr
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.
A new cantilever beam-rigid-body MEMS gyroscope: mathematical model and linear dynamics
Lajimi, Seyed Amir Mousavi; Abdel-Rahman, Eihab
2014-01-01
A new microbeam-rigid-body gyroscope is introduced and its static and dynamic behaviours are studied. The main structure includes a microbeam and an eccentric end-rigid-body influencing the dynamic and static characteristics of the sensor. The sensitivity of the device and the effect of system parameters on the microsystem's response are investigated.
Dynamics of the echolocation beam during prey pursuit in aerial hawking bats
DEFF Research Database (Denmark)
Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie
2015-01-01
In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats...... of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency...... from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral "vision...
MEASUREMENT OF THE TRANSVERSE BEAM DYNAMICS IN A TESLA-TYPE SUPERCONDUCTING CAVITY
Energy Technology Data Exchange (ETDEWEB)
Halavanau, A. [NICADD, DeKalb; Eddy, N. [Fermilab; Edstrom, D. [Fermilab; Lunin, A. [Fermilab; Piot, P. [NICADD, DeKalb; Ruan, J. [Fermilab; Solyak, N. [Fermilab
2016-09-26
Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread applications in Science and Industry. Many project are based on the 1.3-GHz TESLA-type superconducting cavity. In this paper we provide an update on a recent experiment aimed at measuring the transfer matrix of a TESLA cavity at the Fermilab Accelerator Science and Technology (FAST) facility. The results are discussed and compared with analytical and numerical simulations.
Effects of Structural Damage on Dynamic Behavior at Sandwich Composite Beams – Part II- FEM Analysis
Directory of Open Access Journals (Sweden)
Marius Tufoi
2014-07-01
Full Text Available This paper presents results obtained by modal analysis on composite beam like structures in healthy and damaged state. The aim is to obtain damage “signatures” for all possible damage scenarios and to use these data to assess transversal cracks based on vibration techniques, by involving natural frequency shifts. The analysis was performed in SolidWorks software for a five-layer composite, 20 vibration modes being obtained by numerical simulation.
Beam dynamics studies of the ISOLDE post-accelerator for the high intensity and energy upgrade
Fraser, M A
2012-01-01
The High Intensity and Energy (HIE) project represents a major upgrade of the ISOLDE (On-Line Isotope Mass Separator) nuclear facility at CERN with a mandate to significantly increase the energy, intensity and quality of the radioactive nuclear beams provided to the European nuclear physics community for research at the forefront of topics such as nuclear structure physics and nuclear astrophysics. The HIE-ISOLDE project focuses on the upgrade of the existing Radioactive ion beam EXperiment (REX) post-accelerator with the addition of a 40MVsuperconducting linac comprising 32 niobium sputter-coated copper quarter-wave cavities operating at 101.28 MHz and at an accelerating gradient close to 6 MV/m. The energy of post-accelerated radioactive nuclear beams will be increased from the present ceiling of 3 MeV/u to over 10 MeV/u, with full variability in energy, and will permit, amongst others, Coulomb interaction and few-nucleon transfer reactions to be carried out on the full inventory of radionuclides available ...
Beam Dynamics Studies of the ISOLDE Post-accelerator for the High Intensity and Energy Upgrade
Fraser, Matthew Alexander; Pasini, M
2012-01-01
The High Intensity and Energy (HIE) project represents a major upgrade of the ISOLDE (On-Line Isotope Mass Separator) nuclear facility at CERN with a mandate to significantly increase the energy, intensity and quality of the radioactive nuclear beams provided to the European nuclear physics community for research at the forefront of topics such as nuclear structure physics and nuclear astrophysics. The HIE-ISOLDE project focuses on the upgrade of the existing Radioactive ion beam EXperiment (REX) post-accelerator with the addition of a 40MVsuperconducting linac comprising 32 niobium sputter-coated copper quarter-wave cavities operating at 101.28 MHz and at an accelerating gradient close to 6 MV/m. The energy of post-accelerated radioactive nuclear beams will be increased from the present ceiling of 3 MeV/u to over 10 MeV/u, with full variability in energy, and will permit, amongst others, Coulomb interaction and few-nucleon transfer reactions to be carried out on the full inventory of radionuclides available ...