Breakup Effects Research Articles

Investigation of breakup effects on 6Li + 144Sm scattering by means of CDCC calculations

The effect of the breakup of the weakly bound 6Li projectile on the elastic channel of the 6Li$ + $144Sm system is investigated. CDCC calculations are performed by explicitly taking into account the breakup channel and are compared with very precise elastic scattering angular distributions around the Coulomb barrier. The breakup effect is to produce a repulsive polarization potential.

Dip-coating of chemically patterned surfaces

For the purpose of solution-based manufacturing of organic electronic devices, we conducted dip-coating experiments on flat, chemically patterned surfaces. The patterns consisted of long wettable lines of varying width or triangles of different base lengths on an otherwise non-wettable surface. The thickness of the coated film has been measured as a function of pattern dimensions and coating speed. For lines of width comparable to the capillary length, i.e. several millimeters, which were oriented with the long axis parallel to the direction of withdrawal, qualitative agreement has been found with analytical results by Landau and Levich [1], Darhuber et al. [5] and Davis [6]. For narrower lines, quantitative agreement was found. Whereas the coating of long lines is essentially a steady-state process, the coating of compact shapes such as circles and squares is intrinsically time-dependent and involves capillary break-up effects. Nevertheless, for equilateral triangles oriented tip-down, the dependence of film thickness on coating speed and pattern dimensions was found to resemble the behavior of long lines.

Barrier distribution fromBe9+Pb208quasielastic scattering: Breakup effects in the interaction processes

Excitation function of the quasielastic (QEL) scattering at a backward angle was measured for the weakly bound projectile $^{9}\mathrm{Be}$, which bombarded a $^{208}\mathrm{Pb}$ target at near-barrier energies. Barrier distribution was extracted by means of the first derivative of the experimental cross sections with respect to the effective energies. Theoretical fusion barrier distribution has been calculated with the coupled-channels model and compared with the experimental barrier distribution. By this comparison, it is shown that the experimental barrier distribution extracted from QEL scattering is shifted to low energy by 1.5 MeV as compared with the theoretical one. This energy discrepancy between the theoretical prediction and the experimental data indicates the breakup is an important reaction mechanism in the colliding processes of the weakly bound projectile $^{9}\mathrm{Be}$ on a spherical target $^{208}\mathrm{Pb}$.

Pseudo Zero-Dimension Dimming for Power Reduction in Field Sequential Color Liquid Crystal Display Systems

Expensive hardware is required by the conventional two-dimensional (2-D) light-emitting diode (LED) dimming technique to obtain high-contrast and low-power in the field sequential color (FSC) technique. Thus, based on real-time image data, the pseudo zero-dimension (0-D) LED dimming technique is proposed to further reduce power dissipation in the D-FSC technique, which allows the intelligent selection of an adequate color sequence. The multi-liquid crystal and backlight (LC/BL) algorithm utilizes the D-FSC technique in temporal and spatial domains. It not only utilizes the pseudo 0-D technique to effectively reduce the color breakup (CBU) effect without greatly increasing frame rate, but also to reduce power consumption. On the backlight module, CBU suppression can be substantially improved and power dissipation can be reduced by at least 12.5%. Power consumption can also be further reduced through the re-dimming improvement in the proposed pseudo 0-D dimming technique.

Simultaneous analysis of near-barrier elastic scattering and fusion ofBe9withAl27

A simultaneous analysis of elastic scattering and fusion of the weakly bound projectile $^{9}\mathrm{Be}$ with the light deformed $^{27}\mathrm{Al}$ target,at energies close to the Coulomb barrier, is carried out by optical model calculations. The nuclear polarization potential $U$ is split into a volume part ${U}_{F}$, which accounts for fusion reactions and a surface part ${U}_{\mathrm{DR}}$, responsible for the direct reactions. The presence of the threshold anomaly in the elastic scattering is investigated. We also estimate the distance where breakup starts to occur. The present results are compared with those for the same projectile on the medium size and spherical $^{144}\mathrm{Sm}$ target, to investigate the effect of the Coulomb breakup and target deformation in the behavior of the elastic scattering.

Effect of vertical large eddy breakup devices on the drag of a flat plate

Experiments are performed to study the possibility of decreasing the net drag of a flat plate with the use of streamwise-oriented vertical elements mounted normal to the surface in an incompressible equilibrium turbulent boundary layer. The Reynolds number based on the boundary-layer momentum thickness in the section where the vertical elements are placed is 820. It is demonstrated that vertical large eddy breakup elements with the geometry used do not reduce the drag of a flat plate in the major part of the range of Reynolds numbers Rex examined. It is only at extremely low values of Rex that a certain gain in the net drag is reached, as compared with the value for a non-modified flow.

Cherenkov radiation and dielectric based accelerating structures: Wakefield generation, power extraction and energy transfer efficiency

We present here our recent results of the Euclid Techlabs LLC/Argonne National Laboratory/St.Petersburg Electrotechnical University "LETI" collaboration on wakefield high energy acceleration of electron bunches in dielectric based accelerating structures. This program concentrates primarily on Cherenkov radiation studies providing efficient high energy generation aimed at a future 1 TeV collider. We report here on recent experiments in high power Cherenkov radiation and corresponding dielectric material developments and characterizations. Progress in diamond, quartz and microwave low-loss ceramic structure development in GHz and THz frequency ranges is presented. Beam Breakup effects and transverse bunch stability are discussed as well. We e report on recent progress on tunable dielectric based structure development. A special subject of our paper is transformer ratio enhancement schemes providing energy transfer efficiency for the dielectric based wakefield acceleration.

Effect of coalescence and breakup on bubble size distributions in a two-dimensional packed bed

Bubble size distributions in a two-dimensional packed bed are investigated as a function of axial direction by using image processing techniques with a large number of bubble samples. Two inlet conditions, controlled sized bubbles and uncontrolled sized bubbles, are conducted to study the characteristic behaviors of bubbles. With the uncontrolled sized bubbles, the average bubble size corresponding to the two-dimensional bed is found, and is not affected by decrease or increase of flow rates. With the controlled sized bubbles, dominant bubble breakup and coalescence flows are separately simulated to investigate bubble breakup and coalescence rates. Unique behavior of bubble size distributions for dominant bubble breakup and coalescence has been seen, and changes in bubble size distributions along axial direction are studied with median bubble size. Near the inlet the median changes rapidly due to the dominant bubble mechanism of either coalescence or breakup, and far away from the inlet the median reaches asymptotic value due to the balance of bubble breakup and coalescence. For both dominant breakup and coalescence flows, the asymptotic values are close to the average bubble size. Therefore, the average bubble size, resulting from the balance of bubble coalescence and breakup at far downstream, is irrespective of inlet flow conditions.

Analytic model for the breakup of a coasting beam with space charge in isochronous accelerators

An analytical model based on the negative mass instability is introduced in this paper to explain the formation of the breakup of a coasting beam into small clusters in isochronous machines such as the case observed by Pozdeyev and Rodriguez in a small isochronous ring. Solving Poisson’s equation in both charge and vacuum regions with the longitudinal beam density perturbation, the coherent radial space charge force which decreases the transition gamma is obtained. It is found that the modified transition gamma depends on the wave number of the density perturbation, longitudinal beam density distribution, beam intensity, and beam size. By combining the longitudinal space charge force caused by the perturbation and the modified transition gamma, a dispersion relation for a monoenergetic beam is derived and evaluated for the fastest-growing instability mode in terms of the beam parameters, such as energy, bunch length, intensity, and emittance. The fastest-growing negative mass mode number, which determines not only the cluster number but also the growth rate of the instability, is proportional to the orbit radius and inversely proportional to the initial beam size. With the growth of the instability, the particles at the points of local minimum density move to the ones of local maximum density, with the transition gamma increasing. Since the growth rate depends on the longitudinal density distribution, therefore, instead of a constant growth rate, our model shows that the growth rate decreases with time. The results above can be applied to both short and long wavelength limits. As an important application of this theory, the beam breakup effect in the isochronous cyclotron CYCIAE-100 is predicted.

Interplay between the 8B breakup and other reaction mechanisms by means of CDCC method

We use the continuum discretized coupled channel method to study the effects of breakup on different reaction mechanisms for the 8B + 58Ni system. We devote special attention to the role of continuum-continuum couplings.

Experimental investigation of the extraction of solitons at the initial stage of the soliton formation process

We demonstrate the extraction of a single soliton from a bunch of solitons generated by the pulse breakup effect. The bunch of solitons was generated in a 500-m fiber pumped by 25-ps pulses. For the extraction of single soliton from the bunch we use a nonlinear optical loop mirror (NOLM). At its output we detected a pulse with full width at half-maximum (FWHM) of 0.99 ps whose autocorrelation trace corresponds to that of a soliton. Our results demonstrate that the suggested method can be useful for soliton generation, and also for investigations of the initial stage of the soliton formation process.

6He + 9Be reactions at 16.8 MeV

Reactions of a 16.8 MeV 6He beam with a 9Be target have been investigated using highly segmented detector setup covering a large solid angle. Data on elastic and quasi-free scattering, as well as two-neutron transfer, are reported. The results for elastic scattering are fairly well reproduced by a CDCC calculation, in agreement with the interpretation of a breakup effect already observed for the scattering of 6He on other light targets. Exotic quasi-free scattering of 6He on \( \alpha\) -cluster in 9Be is clearly observed. Inclusive and coincident events were used to extract information on the two-neutron transfer reaction 9Be(6He,\( \alpha\))11Be . Sequential decay of the 11Be state at the excitation energy \(\ensuremath E_x = 10.6\) MeV through different channels is discussed.

Divide and Privatize: Firms Break-Up and Performance

We analyze the long-term effects of firm break-up and ownership change on corporate performance. Our analysis is based on a unique data set for a large number of Czech firms spanning the period 1996–2005. We employ a propensity score matching procedure to deal with endogeneity problems. Our results, which are generally in line with the positive effects of firm break-up found in the developed-market literature, show that the initial effects of firm break-up are positive but after a certain point they quickly diminish over time. Factors like changes in ownership structure and management are to be found behind later improvements in the performance of firms.

Deuteron breakup effects on activation cross sections at low and medium energies

An extended analysis of the reaction mechanisms involved in the deuterons interaction with light and medium nuclei, 27Al and 63,65Cu, at incident energies from 3 to 60 MeV starting with elastic scattering until the evaporation from fully equilibrated compound system is presented. An increased attention is devoted to the breakup mechanism, all its components, the elastic, inelastic (fusion), and total breakup, being carefully analysed. Moreover, the corresponding stripping mechanism contribution to the (d, p) and (d, n) reaction cross sections through population of the discrete levels of the residual nuclei, was calculated. Finally, following the decay path, the pre-equilibrium and evaporation cross sections, corrected for the breakup and stripping decrease of the total reaction cross section, have completed the deuteron activation cross sections analysis. The overall agreement between the measured data and model calculations proves the correctness of nuclear mechanism description taken into account for the deuteron-nucleus interaction.

Joint Venture Breakup and the Exploration-Exploitation Trade-off

This paper explores the effect of a potential joint-venture breakup on the level of technology transfer in a set-up with exploration-exploitation trade-offs in the presence of time compression costs. We consider a joint-venture relationship between a technologically advanced multinational firm and a local firm operating in a developing economy where the ability to enforce contracts is weak, and the local firm can quit without penalties. The multinational firm has to consider the advantages and disadvantages of an intensive transfer of technology versus an extensive one. In response to the breakup incentives, the multinational firm reduces the intensity (lowering the pace) and opts for a more extensive transfer mode (longer duration of transfer), compared to the first best. The scheme is supported by a flow of side payments to encourage the local firm to stay longer. We show that a fall in time compression costs may increase or decrease the intensity of technology transfer, both in the first-best and in the second-best scenarios, depending on the nature of the saving in time-compression costs.

Extended optical model analyses for the 11B + 209Bi system at near-Coulomb-barrier energies

In the framework of an extended optical model approach in which the polarization potential is decomposed into direct-reaction (DR) and fusion parts, simultaneous \( \chi^{{2}}_{}\) analyses of elastic scattering and fusion cross-section data for the 11B$ + $209Bi system at near-Coulomb-barrier energies are performed. We show that the DR and fusion potentials extracted from \( \chi^{{2}}_{}\) analyses separately satisfy the dispersion relation and that the threshold anomaly exhibits in both DR and fusion parts. We find that the analyses using only elastic scattering and fusion data can produce reliable predictions of cross-sections even though the direct reaction cross-section data are not complete. By using the extracted DR potential, we investigate the effects of the projectile breakup on fusion cross-sections.

New Approach for Evaluating Incomplete and Complete Fusion Cross Sections with Continuum-Discretized Coupled-Channels Method

We propose a new method for evaluating incomplete and complete fusion cross sections separately using the Continuum-Discretized Coupled-Channels method. This method is applied to analysis of the deuteron induced reaction on a 7Li target up to 50 MeV of the deuteron incident energy. Effects of deuteron breakup on this reaction are explicitly taken into account. Results of the method are compared with those of the Glauber model, and the difference between the two is discussed. It is found that the energy dependence of the incomplete fusion cross sections obtained by the present calculation is almost the same as that obtained by the Glauber model, while for the complete fusion cross section, the two models give markedly different energy dependence. We show also that a prescription for evaluating incomplete fusion cross sections proposed in a previous study gives much smaller result than an experimental value.

Effects of group-delay difference on ultrashort pulse propagation in an active nonlinear LPFG

The effects of group-delay difference in an active nonlinear long-period fiber grating (LPFG) made in an erbium-doped amplifying fiber (EDF) are investigated by proposing a general model that include the effects of detuning, group-delay difference, gain saturation, gain bandwidth and Kerr nonlinearity. In particular, we observe a new feature caused by the interaction between the group-delay difference and the gain bandwidth: the pulse breakup effect due to the group-delay difference can be suppressed by the finite bandwidth of the linear gain.

Mid-Cretaceous seafloor spreading pulse: Fact or fiction?

Research Article| August 01, 2009 Mid-Cretaceous seafloor spreading pulse: Fact or fiction? M. Seton; M. Seton * 1EarthByte Group, School of Geosciences, Madsen Building F09, University of Sydney, Sydney, NSW 2006, Australia *E-mail: maria.seton@usyd.edu.au. Search for other works by this author on: GSW Google Scholar C. Gaina; C. Gaina 2Center for Geodynamics, Geological Survey of Norway, Leiv Eirikssons vei 39, N-7491 Trondheim, Norway Search for other works by this author on: GSW Google Scholar R.D. Müller; R.D. Müller 1EarthByte Group, School of Geosciences, Madsen Building F09, University of Sydney, Sydney, NSW 2006, Australia Search for other works by this author on: GSW Google Scholar C. Heine C. Heine 1EarthByte Group, School of Geosciences, Madsen Building F09, University of Sydney, Sydney, NSW 2006, Australia †Current address: StatoilHydro Global Exploration Technology, Drammensveien 264, N-0246 Oslo, Norway Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (8): 687–690. https://doi.org/10.1130/G25624A.1 Article history received: 23 Oct 2008 rev-recd: 18 Mar 2009 accepted: 22 Mar 2009 first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation M. Seton, C. Gaina, R.D. Müller, C. Heine; Mid-Cretaceous seafloor spreading pulse: Fact or fiction?. Geology 2009;; 37 (8): 687–690. doi: https://doi.org/10.1130/G25624A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Two main hypotheses compete to explain the mid-Cretaceous global sea-level highstand: a massive pulse of oceanic crustal production that occurred during the Cretaceous Normal Superchron (CNS) and the “supercontinent breakup effect,” which resulted in the creation of the mid-Atlantic and Indian ocean ridges at the expense of subducting old ocean floor in the Tethys and the Pacific. We have used global oceanic paleo-age grids, including now subducted ocean floor and two alternative time scales, to test these hypotheses. Our models show that a high average seafloor spreading rate of 92 mm/a in the Early Cretaceous that decreased to 60 mm/a during the Tertiary, with peaks of 86 mm/a and 70 mm/a at 105 Ma and 75 Ma ago, respectively, correspond to the two observed sea-level highstands in the Cretaceous. Calculations using GTS2004 produce lower seafloor spreading rates during the same period and diminish the mid-Cretaceous spreading pulse. Global ridge lengths increased in the earliest Cretaceous but stayed relatively constant through time. However, we find that the average age of the ocean basins through time is only weakly dependent on the choice of time scale. The expansive mid- and Late Cretaceous epicontinental seas, coupled with warm climates and oxygen-poor water masses, were ultimately driven by the younger average age of the Cretaceous seafloor and faster seafloor spreading rather than a vast increase in mid-ocean ridge length due to the breakup of Pangea or solely by higher seafloor spreading rates, as suggested previously. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Modeling of low-pressure subcooled boiling flow of water via the homogeneous MUSIG approach

Applying a three-dimensional two-fluid model coupled with homogeneous multiple size group (MUSIG) approach, numerical simulations of upward subcooled boiling flow of water at low pressure were performed on the computational fluid dynamics (CFD) code CFX-10 with user defined FORTRAN program. A modified bubble departure diameter correlation based on the Unal's semi-mechanistic model and the empirical correlation of Tolubinski and Kostanchuk was developed. The water boiling flow experiments at low pressure in a vertical concentric annulus from reference were used to validate the models. Moreover, the influences of the non-drag force on the radial void fraction distribution were investigated, including lift force, turbulent dispersion force and wall lubrication force. Good quantitative agreement with the experimental data is obtained, including the local distribution of bubble diameter, void fraction, and axial liquid velocity. The results indicate that the local bubble diameter first increases and then decreases due to the effect of bubble breakup and coalescence, and has the maximum bubble diameter along the radial direction. Especially, the peak void fraction phenomenon in the vicinity of the heated wall is predicted at low pressure, which is developed from the wall repulsive force between vapor bubbles and heated wall. Nevertheless, there is a high discrepancy for the prediction of the local axial vapor velocity.