Indian Academy of Sciences (India)
A E Kotp
2011-04-01
The study of thermally stimulated depolarization current (TSDC) using the dipole–dipole interaction model is described in this work. The dipole–dipole interactionmodel (DDIM) determines the TSDC peak successfully since it gives significant peak parameters (i.e. activation energy () and pre-exponential factor ($\\tau_{0}$)) in addition to the dipole–dipole interaction strength parameter ($d_{i}$). Application of this model to study the peak parameters of some polymeric systems is presented.
Clinical utility of current-generation dipole modelling of scalp EEG.
Plummer, C; Litewka, L; Farish, S; Harvey, A S; Cook, M J
2007-11-01
To investigate the clinical utility of current-generation dipole modelling of scalp EEG in focal epilepsies seen commonly in clinical practice. Scalp EEG recordings from 10 patients with focal epilepsy, five with Benign Focal Epilepsy of Childhood (BFEC) and five with Mesial Temporal Lobe Epilepsy (MTLE), were used for interictal spike dipole modelling using Scan 4.3 and CURRY 5.0. Optimum modelling parameters for EEG source localisation (ESL) were sought by the step-wise application of various volume conductor (forward) and dipole (inverse) models. Best-fit ESL solutions (highest explained forward-fit to measured data variance) were used to characterise best-fit forward and inverse models, regularisation effect, additional electrode effect, single-to-single spike and single-to-averaged spike variability, and intra- and inter-operator concordance. Inter-parameter relationships were examined. Computation times and interface problems were recorded. For both BFEC and MTLE, the best-fit forward model was the finite element method interpolated (FEMi) model, while the best-fit single dipole models were the rotating non-regularised and the moving regularised models. When combined, these forward-inverse models appeared to offer clinically meaningful ESL results when referenced to an averaged cortex overlay, best-fit dipoles localising to the central fissure region in BFEC and to the basolateral temporal region in MTLE. Single-to-single spike and single-to-averaged spike measures of concordance for dipole location and orientation were stronger for BFEC versus MTLE. The use of an additional pair of inferior temporal electrodes in MTLE directed best-fit dipoles towards the basomesial temporal region. Inverse correlations were noted between unexplained variance (RD) and dipole strength (Amp), RD and signal to noise ratio (SNR), and SNR and confidence ellipsoid (CE) volume. Intra- and inter-operator levels of agreement were relatively robust for dipole location and orientation
Modeling left and right atrial contributions to the ECG: A dipole-current source approach.
Jacquemet, Vincent
2015-10-01
This paper presents the mathematical formulation, the numerical validation and several illustrations of a forward-modeling approach based on dipole-current sources to compute the contribution of a part of the heart to the electrocardiogram (ECG). Clinically relevant applications include identifying in the ECG the contributions from the right and the left atrium. In a Courtemanche-based monodomain computer model of the atria and torso, 1000 dipoles distributed throughout the atrial mid-myocardium are found to be sufficient to reproduce body surface potential maps with a relative error approach enables fast offline computation of the ECG contribution of any anatomical part of the atria by applying the principle of superposition to the dipole sources. In the presence of a right-left activation delay (sinus rhythm), pulmonary vein isolation (sinus rhythm) or left-right differences in refractory period (atrial fibrillation), the decomposition of the ECG is shown to help interpret ECG morphology in relation to the atrial substrate. These tools provide a theoretical basis for a deeper understanding of the genesis of the P wave or fibrillatory waves in normal and pathological cases.
Konn, Daniel; Gowland, Penny; Bowtell, Richard
2003-07-01
To investigate the feasibility of direct MR detection of neuronal activity in the brain, neuronal current flow was modeled as an extended current dipole located in a conducting sphere. The spatially varying magnetic field induced within the sphere by such a dipole was calculated, including its form close to and within the current source. The predicted field variation was experimentally verified by measurements of the variation in phase of the MR signal in a sphere containing a model dipole. The effects of the calculated magnetic field distributions on the phase and magnitude of the signal in MR images were explored. The minimum detectable dipole strength under normal experimental conditions was calculated to be about 4.5 nAm, which is similar in magnitude to dipole strengths from evoked neuronal activity, and is an order of magnitude smaller than dipole strengths expected from spontaneous activity. This minimum detectable dipole strength increases with increasing spatial extent of the primary current distribution. In the experimental work, the effects of a field of [1.1 +/- 0.5] x 10(-10) T strength were detected, corresponding to the maximum net field caused by a dipole of 6.3 nAm strength with a spatial extent of 3 x 3 x 2 mm(3). Copyright 2003 Wiley-Liss, Inc.
Thompson, N; Thompson, G; Cole, C D; Cotten, M; Cross, T A; Busath, D D
2001-09-01
Nonlinear least squares fitting was used to assign rate constants for the three-barrier, two-site, double-occupancy, single-filing kinetic model for previously reported current-voltage relations of (5F-Indole)Trp(13) gramicidin A and gramicidin A channels (, 75:2830-2844). By judicious coupling of parameters, it was possible to reduce the parameter space from 64 parameters to 24, and a reasonable fit consistent with other experimental data was obtained. The main features of the fit were that fluorination increased the rate constant for translocation by a factor of 2.33, consistent with a free energy change in the translocation barrier of -0.50 kcal/mol, and increased first-ion binding affinity by a factor of 1.13, primarily by decreasing the first-ion exit rate constant. The translocation rate constant was 5.62 times slower in diphytanoyl phosphatidylcholine (DPhPC) bilayers than in monoolein (GMO) bilayers (coupled for the four combinations of peptide and salt), suggesting a 44.2-mV difference in the projection of the interfacial dipole into the channel. Thus fluorination caused increased currents in DPhPC bilayers, where a high interfacial dipole potential makes translocation more rate limiting because the translocation barrier was reduced, and decreased currents in GMO bilayers, where ion exit or entry is rate limiting because these barriers were increased.
Perturbative Odderon in the Dipole Model
Kovchegov, Yu V; Wallon, S; Kovchegov, Yuri V.; Szymanowski, Lech; Wallon, Samuel
2003-01-01
We show that, in the framework of Mueller's dipole model, the perturbative QCD odderon is described by the dipole model equivalent of the BFKL equation with a $C$-odd initial condition. The eigenfunctions and eigenvalues of the odderon solution are the same as for the dipole BFKL equation and are given by the functions $E^{n,\
He, S; Norgren, M
2000-02-01
The image solution for the static magnetic field outside a conducting sphere with an internal current dipole is considered. The image current, which is a linear distribution of magnetic dipoles on the line segment between the dipole point and the center of the sphere, is derived by using the fact that the induced current does not have any contribution to the radial component of the magnetic field outside the sphere. The image is then used to obtain some explicit formulas for identifying the location and tangential moment of the primary current dipole. This explicit identification method is also tested with a real model for a patient's brain.
Acceleration of magnetic dipoles by the sequence of current turns
Dolya, S N
2014-01-01
Acceleration of magnetic dipoles is carried out by the running gradient of the magnetic field formed while sequent switching on the current turns. Magnetic dipoles, with a diameter of sixty millimeters and full length one meter, are pre-accelerated by using the gas-dynamic method to speed one kilometer per second, corresponding to the injection rate into the main accelerator. To prevent the turning of the dipoles by one hundred eighty degrees in the field of the accelerating pulse and focus them, the magnetic dipoles are accelerated inside the titanium tube. The magnetic dipoles have mass two kilograms and acquire the finite speed five kilometers per second on the acceleration length three hundreds meters.
Energy Technology Data Exchange (ETDEWEB)
Grespan, F. [INFN-Laboratori Nazionali di Legnaro, Viale dell' universita 2, 35020 Legnaro, PD (Italy); Universita degli Studi di Milano, Dipartimento di Fisica, via Celoria, 16 I-20133 Milan (Italy)], E-mail: francesco.grespan@lnl.infn.it; Pisent, A.; Palmieri, A. [INFN-Laboratori Nazionali di Legnaro, Viale dell' universita 2, 35020 Legnaro, PD (Italy)
2007-11-21
The Dipole Stabilizing Rods (DSRs) are devices used in order to reduce a priori the effect of perturbation on the operating mode of a four-vane RFQ caused by neighboring dipole modes by increasing the frequency spacing between the TE210 mode and dipole modes, without, in principle, affecting the quadrupole TE210 mode. They have proven to be particularly useful in the case of coupled RFQ's whose overall length is significantly greater than the operating wavelength. In this article we present a circuit model of such DSRs, that, used in combination with a Transmission Line Model of a four vane RFQ, has allowed us to predict the dimensioning of the DSRs in the case of the aluminium model of TRASCO RFQ. The DSR parameters and, in general, the accuracy of the model have been also confirmed by HFSS simulations and by RF measurements on the above-mentioned model.
Mu, Yan; Gao, Yi Qin
2007-09-01
We studied the effects of hydrophobicity and dipole-dipole interactions between the nearest-neighbor amide planes on the secondary structures of a model polypeptide by calculating the free energy differences between different peptide structures. The free energy calculations were performed with low computational costs using the accelerated Monte Carlo simulation (umbrella sampling) method, with a bias-potential method used earlier in our accelerated molecular dynamics simulations. It was found that the hydrophobic interaction enhances the stability of α helices at both low and high temperatures but stabilizes β structures only at high temperatures at which α helices are not stable. The nearest-neighbor dipole-dipole interaction stabilizes β structures under all conditions, especially in the low temperature region where α helices are the stable structures. Our results indicate clearly that the dipole-dipole interaction between the nearest neighboring amide planes plays an important role in determining the peptide structures. Current research provides a more unified and quantitative picture for understanding the effects of different forms of interactions on polypeptide structures. In addition, the present model can be extended to describe DNA/RNA, polymer, copolymer, and other chain systems.
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Gaididei, Yuri Borisovich; Johansson, M.
1998-01-01
The dynamics of discrete two-dimensional nonlinear Schrodinger models with long-range dispersive interactions is investigated. In particular, we focus on the cases where the dispersion arises from a dipole-dipole interaction, assuming the dipole moments at each lattice site to be aligned either...
Directional Dipole Model for Subsurface Scattering
DEFF Research Database (Denmark)
Frisvad, Jeppe Revall; Hachisuka, Toshiya; Kjeldsen, Thomas Kim
2014-01-01
Rendering translucent materials using Monte Carlo ray tracing is computationally expensive due to a large number of subsurface scattering events. Faster approaches are based on analytical models derived from diffusion theory. While such analytical models are efficient, they miss out on some...... point source diffusion. A ray source corresponds better to the light that refracts through the surface of a translucent material. Using this ray source, we are able to take the direction of the incident light ray and the direction toward the point of emergence into account. We use a dipole construction...... similar to that of the standard dipole model, but we now have positive and negative ray sources with a mirrored pair of directions. Our model is as computationally efficient as existing models while it includes single scattering without relying on a separate Monte Carlo simulation, and the rendered images...
Projected Dipole Model for Quantum Plasmonics
DEFF Research Database (Denmark)
Yan, Wei; Wubs, Martijn; Mortensen, N. Asger
2015-01-01
Quantum effects of plasmonic phenomena have been explored through ab initio studies, but only for exceedingly small metallic nanostructures, leaving most experimentally relevant structures too large to handle. We propose instead an effective description with the computationally appealing features...... of classical electrodynamics, while quantum properties are described accurately through an infinitely thin layer of dipoles oriented normally to the metal surface. The nonlocal polarizability of the dipole layer-the only introduced parameter-is mapped from the free-electron distribution near the metal surface...... as obtained with 1D quantum calculations, such as time-dependent density-functional theory (TDDFT), and is determined once and for all. The model can be applied in two and three dimensions to any system size that is tractable within classical electrodynamics, while capturing quantum plasmonic aspects...
Acceleration of magnetic dipoles by a sequence of current-carrying turns
Dolya, S. N.
2014-11-01
Magnetic dipoles are accelerated by a running gradient of the magnetic field that is produced by sequentially energizing current-carrying turns. Magnetic dipoles d sh = 60 mm in diameter and l tot = 1 m in length are gasdynamically preaccelerated to velocity V in = 1 km/s, with which they are injected into the main accelerator. The turnover of the dipoles in the field of an accelerating pulse is prevented and focusing of dipoles is provided by directing the dipoles into a titanium tube. The weight of the dipoles is m = 2 kg, and they acquire final velocity V fin = 5 km/s over acceleration length L acc = 300 m.
Energy Technology Data Exchange (ETDEWEB)
Nara, Takaaki [Graduate School of Information Science and Technology, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Oohama, Junji [Graduate School of Information Science and Technology, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Hashimoto, Masaru [Graduate School of Information Science and Technology, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Takeda, Tsunehiro [Graduate School of Frontier Science, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8561 (Japan); Ando, Shigeru [Graduate School of Information Science and Technology, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656 (Japan)
2007-07-07
This paper presents a novel algorithm to reconstruct parameters of a sufficient number of current dipoles that describe data (equivalent current dipoles, ECDs, hereafter) from radial/vector magnetoencephalography (MEG) with and without electroencephalography (EEG). We assume a three-compartment head model and arbitrary surfaces on which the MEG sensors and EEG electrodes are placed. Via the multipole expansion of the magnetic field, we obtain algebraic equations relating the dipole parameters to the vector MEG/EEG data. By solving them directly, without providing initial parameter guesses and computing forward solutions iteratively, the dipole positions and moments projected onto the xy-plane (equatorial plane) are reconstructed from a single time shot of the data. In addition, when the head layers and the sensor surfaces are spherically symmetric, we show that the required data reduce to radial MEG only. This clarifies the advantage of vector MEG/EEG measurements and algorithms for a generally-shaped head and sensor surfaces. In the numerical simulations, the centroids of the patch sources are well localized using vector/radial MEG measured on the upper hemisphere. By assuming the model order to be larger than the actual dipole number, the resultant spurious dipole is shown to have a much smaller strength magnetic moment (about 0.05 times smaller when the SNR = 16 dB), so that the number of ECDs is reasonably estimated. We consider that our direct method with greatly reduced computational cost can also be used to provide a good initial guess for conventional dipolar/multipolar fitting algorithms.
Photo-induced dipole relaxation current in natural Amethyst
Directory of Open Access Journals (Sweden)
Fabricio Trombini Russo
2012-06-01
Full Text Available Thermally stimulated depolarization current (TSDC measurements were carried out for SiO2 in the amethyst form, aiming to investigate the relationship of observed current with relaxation phenomena related to quartz impurities. In addition to TSDC conventional dark procedure, photo-induced TSDC was also carried out, where the exciting light came from an Ar+ laser, tuned either at 488 nm or at 541 nm. X-ray diffraction and optical absorption measurements were used as complement for the interpretation of TSDC data. Optical absorption data, mainly in the range 400-700 nm, allow identifying the characteristic bands of amethyst as well as to relate them with TSDC and photo-induced TSDC data, leading to a relationship between absorption bands and light irradiation with selected wavelengths. These results allow determining how the formation of a TSDC band in the range 220-260 K, is affected by the light absorption, modifying the formation and the dipole orientation distribution in the samples. Results also help the verification of defects formed by Fe3+ or Fe4+ ions in the amethyst structure, as well as suggest that these defects, besides the participation in the amethyst structure as color centers, also play a role in the formation of TSDC bands, contributing for the observed effect of monochromatic light irradiation on these bands.
Bellesia, B; Granata, V; Le Naour, S; Oberli, L R; Sanfilippo, S; Santoni, C; Scandale, Walter; Schwerg, N; Todesco, Ezio; Völlinger, C
2004-01-01
The production of more than 60% of superconducting cables for the main dipoles of the Large Hadron Collider has been completed. The results of the measurements of cable magnetization and the dependence on the manufacturer are presented. The strand magnetization produces field errors that have been measured in a large number of dipoles, all tested in cold conditions. We examine here the correlation between the available magnetic measurements and the large database of cable magnetization. The analysis is based on models documented in the literature. Finally, a forecast of the persistent current effects to be expected in the LHC main dipoles is presented, and the more critical parameters for beam dynamics are singled out.
Many-body dipole-induced dipole model for electrorheological fluids
Institute of Scientific and Technical Information of China (English)
Huang Ji-Ping; Yu Kin-Wah
2004-01-01
Theoretical investigations on electrorheological (ER) fluids usually rely on computer simulations. An initial approach for these studies would be the point-dipole (PD) approximation, which is known to err considerably when the particles approach and finally touch each other due to many-body and multipolar interactions. Thus various works have attempted to go beyond the PD model. Being beyond the PD model, previous attempts have been restricted to either local-field effects only or multipolar effects only, but not both. For instance, we recently proposed a dipoleinduced-dipole (DID) model which is shown to be both more accurate than the PD model and easy to use. This work is necessary because the many-body (local-field) effect is included to put forth the many-body DID model. The results show that the multipolar interactions can indeed be dominant over the dipole interaction, while the local-field effect may yield a correction.
Electric Potential in a Dielectric Sphere Head Produced by a Time-Harmonic Equivalent Current Dipole
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A time-harmonic equivalent current dipole model is proposed to simulate EEG source which deals with the problem concerning the capacitance effect. The expressions of potentials in both homogeneous infinite dielectric medium and dielectric sphere on the electroquasistatic condition are presented. The potential in a 3-layer inhomogeneous spherical head is computed by using this model. The influences on potential produced by time-harmonic character and permittivity are discussed. The results show that potentials in dielectric sphere are affected by frequency and permittivity.
QCD dipole model and $k_{T}$ factorization
Bialas, A; Peschanski, R
2001-01-01
It is shown that the colour dipole approach to hard scattering at high energy is fully compatible with k_T factorization at the leading logarithm approximation (in -log x_Bj). The relations between the dipole amplitudes and unintegrated diagonal and non-diagonal gluon distributions are given. It is also shown that including the exact gluon kinematics in the k_T factorization formula destroys the conservation of transverse position vectors and thus is incompatible with the dipole model for both elastic and diffractive amplitudes.
Dipole model test with one superconducting coil; results analysed
Durante, M; Ferracin, P; Fessia, P; Gauthier, R; Giloux, C; Guinchard, M; Kircher, F; Manil, P; Milanese, A; Millot, J-F; Muñoz Garcia, J-E; Oberli, L; Perez, J-C; Pietrowicz, S; Rifflet, J-M; de Rijk, G; Rondeaux, F; Todesco, E; Viret, P; Ziemianski, D
2013-01-01
This report is the deliverable report 7.3.1 “Dipole model test with one superconducting coil; results analysed “. The report has four parts: “Design report for the dipole magnet”, “Dipole magnet structure tested in LN2”, “Nb3Sn strand procured for one dipole magnet” and “One test double pancake copper coil made”. The 4 report parts show that, although the magnet construction will be only completed by end 2014, all elements are present for a successful completion. Due to the importance of the project for the future of the participants and given the significant investments done by the participants, there is a full commitment to finish the project.
Fourier-positivity constraints on QCD dipole models
Directory of Open Access Journals (Sweden)
Bertrand G. Giraud
2016-09-01
Full Text Available Fourier-positivity (F-positivity, i.e. the mathematical property that a function has a positive Fourier transform, can be used as a constraint on the parametrization of QCD dipole-target cross-sections or Wilson line correlators in transverse position space r. They are Bessel transforms of positive transverse momentum dependent gluon distributions. Using mathematical F-positivity constraints on the limit r→0 behavior of the dipole amplitudes, we identify the common origin of the violation of F-positivity for various, however phenomenologically convenient, dipole models. It is due to the behavior r2+ϵ, ϵ>0 softer, even slightly, than color transparency. F-positivity seems thus to conflict with the present dipole formalism when it includes a QCD running coupling constant α(r.
Dipole model test with one superconducting coil: results analysed
Bajas, H; Benda, V; Berriaud, C; Bajko, M; Bottura, L; Caspi, S; Charrondiere, M; Clément, S; Datskov, V; Devaux, M; Durante, M; Fazilleau, P; Ferracin, P; Fessia, P; Gauthier, R; Giloux, C; Guinchard, M; Kircher, F; Manil, P; Milanese, A; Millot, J-F; Muñoz Garcia, J-E; Oberli, L; Perez, J-C; Pietrowicz, S; Rifflet, J-M; de Rijk, G; Rondeaux, F; Todesco, E; Viret, P; Ziemianski, D
2013-01-01
This report is the deliverable report 7.3.1 “Dipole model test with one superconducting coil; results analysed “. The report has four parts: “Design report for the dipole magnet”, “Dipole magnet structure tested in LN2”, “Nb3Sn strand procured for one dipole magnet” and “One test double pancake copper coil made”. The 4 report parts show that, although the magnet construction will be only completed by end 2014, all elements are present for a successful completion. Due to the importance of the project for the future of the participants and given the significant investments done by the participants, there is a full commitment to finish the project.
Murakami, Shingo; Okada, Yoshio
2015-05-01
Although anatomical constraints have been shown to be effective for MEG and EEG inverse solutions, there are still no effective physiological constraints. Strength of the current generator is normally described by the moment of an equivalent current dipole Q. This value is quite variable since it depends on size of active tissue. In contrast, the current dipole moment density q, defined as Q per surface area of active cortex, is independent of size of active tissue. Here we studied whether the value of q has a maximum in physiological conditions across brain structures and species. We determined the value due to the primary neuronal current (q primary) alone, correcting for distortions due to measurement conditions and secondary current sources at boundaries separating regions of differing electrical conductivities. The values were in the same range for turtle cerebellum (0.56-1.48 nAm/mm(2)), guinea pig hippocampus (0.30-1.34 nAm/mm(2)), and swine neocortex (0.18-1.63 nAm/mm(2)), rat neocortex (~2.2 nAm/mm(2)), monkey neocortex (~0.40 nAm/mm(2)) and human neocortex (0.16-0.77 nAm/mm(2)). Thus, there appears to be a maximum value across the brain structures and species (1-2 nAm/mm(2)). The empirical values closely matched the theoretical values obtained with our independently validated neural network model (1.6-2.8 nAm/mm(2) for initial spike and 0.7-3.1 nAm/mm(2) for burst), indicating that the apparent invariance is not coincidental. Our model study shows that a single maximum value may exist across a wide range of brain structures and species, varying in neuron density, due to fundamental electrical properties of neurons. The maximum value of q primary may serve as an effective physiological constraint for MEG/EEG inverse solutions.
A dipole interaction model for the molecular second hyperpolarizability
Jensen, L; Sylvester-Hvid, KO; Mikkelsen, KV; Astrand, PO
2003-01-01
A dipole interaction model (IM) for calculating the molecular second hyperpolarizability, gamma, of aliphatic and aromatic molecules has been investigated. The model has been parametrized from quantum chemical calculations of gamma at the self-consistent field (SCF) level of theory for 72 molecules.
Status of the LHC Short Dipole Model Programme
Tommasini, D; Sanfilippo, S; Siemko, A; Vanenkov, I; Wyss, C
2000-01-01
The 1-m model program for the main LHC dipoles is now mainly focussed on double-aperture magnets. In the past years an intensive program based on single-aperture dipoles allowed to select the series-design features among several variants for the coil cross section, the material of the collars and of the coil end spacers, the coil pre-stress and the cable insulation. The recent double-aperture models are dedicated to the fine-tuning of the baseline design and the manufacture of the coil ends. This paper reports about the fabrication and testing of these magnets and the results relevant for the series production of the 15-m long full-size dipole cold masses.
PERSISTENT CURRENT EFFECT IN 15-16 T NB3SN ACCELERATOR DIPOLES AND ITS CORRECTION
Energy Technology Data Exchange (ETDEWEB)
Kashikhin, V. V. [Fermilab; Zlobin, A. V. [Fermilab
2016-11-08
Nb3Sn magnets with operating fields of 15-16 T are considered for the LHC Energy Doubler and a future Very High Energy pp Collider. Due to large coil volume, high critical current density and large superconducting (SC) filament size the persistent current effect is very large in Nb3Sn dipoles al low fields. This paper presents the results of analysis of the persistent current effect in the 15 T Nb3Sn dipole demonstrator being developed at FNAL, and describes different possibilities of its correction including passive SC wires, iron shims and coil geometry.
Nonlinear Dynamics of Dipoles in Microtubules: Pseudo-Spin Model
Nesterov, Alexander I; Berman, Gennady P; Mavromatos, Nick E
2016-01-01
We perform a theoretical study of the dynamics of the electric field excitations in a microtubule by taking into consideration the realistic cylindrical geometry, dipole-dipole interactions of the tubulin-based protein heterodimers, the radial electric field produced by the solvent, and a possible degeneracy of energy states of individual heterodimers. The consideration is done in the frames of the classical pseudo-spin model. We derive the system of nonlinear dynamical ordinary differential equations of motion for interacting dipoles, and the continuum version of these equations. We obtain the solutions of these equations in the form of snoidal waves, solitons, kinks, and localized spikes. Our results will help to a better understanding of the functional properties of microtubules including the motor protein dynamics and the information transfer processes. Our considerations are based on classical dynamics. Some speculations on the role of possible quantum effects are also made.
Nonlinear dynamics of dipoles in microtubules: Pseudospin model.
Nesterov, Alexander I; Ramírez, Mónica F; Berman, Gennady P; Mavromatos, Nick E
2016-06-01
We perform a theoretical study of the dynamics of the electric field excitations in a microtubule by taking into consideration the realistic cylindrical geometry, dipole-dipole interactions of the tubulin-based protein heterodimers, the radial electric field produced by the solvent, and a possible degeneracy of energy states of individual heterodimers. The consideration is done in the frame of the classical pseudospin model. We derive the system of nonlinear dynamical partial differential equations of motion for interacting dipoles and the continuum version of these equations. We obtain the solutions of these equations in the form of snoidal waves, solitons, kinks, and localized spikes. Our results will help to achieve a better understanding of the functional properties of microtubules including the motor protein dynamics and the information transfer processes. Our considerations are based on classical dynamics. Some speculations on the role of possible quantum effects are also made.
Electron electric dipole moment in Inverse Seesaw models
Abada, Asmaa
2016-01-01
We consider the contribution of sterile neutrinos to the electric dipole moment of charged leptons in the most minimal realisation of the Inverse Seesaw mechanism, in which the Standard Model is extended by two right-handed neutrinos and two sterile fermion states. Our study shows that the two pairs of (heavy) pseudo-Dirac mass eigenstates can give significant contributions to the electron electric dipole moment, lying close to future experimental sensitivity if their masses are above the electroweak scale. The major contribution comes from two-loop diagrams with pseudo-Dirac neutrino states running in the loops. In our analysis we further discuss the possibility of having a successful leptogenesis in this framework, compatible with a large electron electric dipole moment.
Modeling and analysis of magnetic dipoles in weak magnetic field
Institute of Scientific and Technical Information of China (English)
2008-01-01
The magnetic leakage field distribution resulting from linear defects of a tube sample in the geomagnetic field is modeled according to the magnetic dipole theory.The formula to compute the normal component of the weak magnetic field is deduced based on the spatial distribution of the magnetic dipole.The shape and characteristics of the zero line (an important criterion for magnetic memory testing) of the normal field is analyzed under different longitudinal magnetizations.Results show that the characteristics of the zero line should be considered when the metal magnetic memory testing method is used to find and locate the defect.
Neutron electric dipole momento in two-Higgs-doublet model
Hayashi, T; Matsuda, M; Tanimoto, M; Hayashi, T; Koide, Y; Matsuda, M; Tanimoto, M
1994-01-01
The effect of the "chromo-electric" dipole moment on the electric dipole moment(EDM) of the neutron is studied in the two-Higgs-doublet model. The Weinberg's operator O_{3g}=GG\\t G and the operator O_{qg}=\\bar q\\sigma\\t Gq are both investigated in the cases of \\tan\\b\\gg 1, \\tan\\b\\ll 1 and \\tan\\b\\simeq 1. The neutron EDM is considerably reduced due to the destructive contribution with two light Higgs scalars exchanges.
Shell Model Estimate of Electric Dipole Moments for Xe Isotopes
Teruya, Eri; Yoshinaga, Naotaka; Higashiyama, Koji
The nuclear Schiff moments of Xe isotopes which induce electric dipole moments of neutral Xe atoms is theoretically estimated. Parity and time-reversal violating two-body nuclear interactions are assumed. The nuclear wave functions are calculated in terms of the nuclear shell model. Influences of core excitations on the Schiff moments in addition to the over-shell excitations are discussed.
Testing the Dipole and Quadrupole Moments of Galactic Models
Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.; Horack, John M.; Kouveliotou, Chryssa; Hartmann, Dieter H.; Hakkila, Jon
1996-01-01
If gamma-ray bursts originate in the Galaxy, at some level there should be a galactic pattern in their distribution on the sky. We test published galactic models by comparing their dipole and quadrupole moments with the moments of the BATSE 3B catalog. While many models have moments that are too large, several models are in acceptable or good agreement with the data.
Dipole-on-dielectric model for infrared lithographic spiral antennas
Energy Technology Data Exchange (ETDEWEB)
Boreman, G.D. [Center for Research and Education in Optics and Lasers and Department of Electrical Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Dogariu, A. [Center for Research and Education in Optics and Lasers, University of Central Florida, Orlando, Florida 32816 (United States); Christodoulou, C. [Department of Electrical Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Kotter, D. [Idaho National Engineering Laboratory, Lockheed-Martin Corporation, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States)
1996-03-01
We present a dipole-on-dielectric model for lithographic antennas used for bolometer coupling in the infrared. The predicted antenna patterns show good agreement with measurements of Au-on-Si spiral antennas at 9.5-{mu}m wavelength. Angle- and polarization-resolved measurements are proposed, which will further probe the behavior of these antenna structures and facilitate refinement of the analytical models. {copyright} {ital 1996 Optical Society of America.}
Nucleon Electric Dipole Moments in High-Scale Supersymmetric Models
Hisano, Junji; Kuramoto, Wataru; Kuwahara, Takumi
2015-01-01
The electric dipole moments (EDMs) of electron and nucleons are the promising probe of the new physics. In the generic high-scale supersymmetric (SUSY) scenarios such as models based on mixture of the anomaly and gauge mediations, gluino has an additional contribution to the nucleon EDMs. In this paper, we estimated the effect of the CP-violating gluon Weinberg operator induced by the gluino chromoelectric dipole moment in the high-scale SUSY scenarios, and we evaluated the nucleon and electron EDMs in these scenarios. We found that in the generic high-scale SUSY models, the nucleon EDMs may receive the sizable contribution from the Weinberg operator. Thus, it is important to compare the nucleon EDMs with the electron EDM in order to discriminate among the high-scale SUSY models.
Nucleon electric dipole moments in high-scale supersymmetric models
Hisano, Junji; Kobayashi, Daiki; Kuramoto, Wataru; Kuwahara, Takumi
2015-11-01
The electric dipole moments (EDMs) of electron and nucleons are promising probes of the new physics. In generic high-scale supersymmetric (SUSY) scenarios such as models based on mixture of the anomaly and gauge mediations, gluino has an additional contribution to the nucleon EDMs. In this paper, we studied the effect of the CP -violating gluon Weinberg operator induced by the gluino chromoelectric dipole moment in the high-scale SUSY scenarios, and we evaluated the nucleon and electron EDMs in the scenarios. We found that in the generic high-scale SUSY models, the nucleon EDMs may receive the sizable contribution from the Weinberg operator. Thus, it is important to compare the nucleon EDMs with the electron one in order to discriminate among the high-scale SUSY models.
A Model for Dipole Modulation of CMBR Polarization
Kothari, Rahul
2015-01-01
I propose a model of dipole modulation in Cosmic Background Microwave Radiation (CMBR) polarization fields Q and U. It is shown that the modulation leads to correlations between l and l multipoles where either l = l or l = l \\pm 1, but the contribution for the case l = l cancels out after summing over m. We perform a detailed mathematical analysis of the E and B mode correlations and obtain the final result in a closed form.
Electric Dipole Moments of Neutron and Electron in Supersymmetric Model
Aoki, Mayumi; Kadoyoshi, Tomoko; Sugamoto, Akio; Oshimo, Noriyuki
1997-01-01
The electric dipole moments (EDMs) of the neutron and the electron are reviewed within the framework of the supersymmetric standard model (SSM) based on grand unified theories coupled to N=1 supergravity. Taking into account one-loop and two-loop contributions to the EDMs, we explore SSM parameter space consistent with experiments and discuss predicted values for the EDMs. Implications of baryon asymmetry of our universe for the EDMs are also discussed.
Braking index of isolated pulsars. II. A novel two-dipole model of pulsar magnetism
Hamil, O.; Stone, N. J.; Stone, J. R.
2016-09-01
The magnetic dipole radiation model is currently the best approach we have to explain pulsar radiation. However, a most characteristic parameter of the observed radiation, the braking index nobs , shows deviations for all the eight best studied isolated pulsars, from the simple model prediction ndip=3 . The index depends upon the rotational frequency and its first and second time derivatives but also on the assumption that the magnetic dipole moment and inclination angle and the moment of inertia of the pulsar are constant in time. In a recent paper [Phys. Rev. D 91, 063007 (2015)], we showed conclusively that changes in the moment of inertia with frequency alone cannot explain the observed braking indices. Possible observational evidence for the magnetic dipole moment migrating away from the rotational axis at a rate α ˙ ˜0.6 ° per 100 years over the lifetime of the Crab pulsar has been recently suggested by Lyne et al. In this paper, we explore the magnetic dipole radiation model with constant moment of inertia and magnetic dipole moment but variable inclination angle α . We first discuss the effect of the variation of α on the observed braking indices and show they all can be understood. However, no explanation for the origin of the change in α is provided. After discussion of the possible source(s) of magnetism in pulsars, we propose a simple mechanism for the change in α based on a toy model in which the magnetic structure in pulsars consists of two interacting dipoles. We show that such a system can explain the Crab observation and the measured braking indices.
Tilted dipole model for bias-dependent photoluminescence pattern
Energy Technology Data Exchange (ETDEWEB)
Fujieda, Ichiro, E-mail: fujieda@se.ritsumei.ac.jp; Suzuki, Daisuke; Masuda, Taishi [Department of Electrical and Electronic Engineering, Ritsumeikan University, Kusatsu 525-8577 (Japan)
2014-12-14
In a guest-host system containing elongated dyes and a nematic liquid crystal, both molecules are aligned to each other. An external bias tilts these molecules and the radiation pattern of the system is altered. A model is proposed to describe this bias-dependent photoluminescence patterns. It divides the liquid crystal/dye layer into sub-layers that contain electric dipoles with specific tilt angles. Each sub-layer emits linearly polarized light. Its radiation pattern is toroidal and is determined by the tilt angle. Its intensity is assumed to be proportional to the power of excitation light absorbed by the sub-layer. This is calculated by the Lambert-Beer's Law. The absorption coefficient is assumed to be proportional to the cross-section of the tilted dipole moment, in analogy to the ellipsoid of refractive index, to evaluate the cross-section for each polarized component of the excitation light. Contributions from all the sub-layers are added to give a final expression for the radiation pattern. Self-absorption is neglected. The model is simplified by reducing the number of sub-layers. Analytical expressions are derived for a simple case that consists of a single layer with tilted dipoles sandwiched by two layers with horizontally-aligned dipoles. All the parameters except for the tilt angle can be determined by measuring transmittance of the excitation light. The model roughly reproduces the bias-dependent photoluminescence patterns of a cell containing 0.5 wt. % coumarin 6. It breaks down at large emission angles. Measured spectral changes suggest that the discrepancy is due to self-absorption and re-emission.
New Constraints from Electric Dipole Moments on Parameters of the Supersymmetric SO(10) Model
Khriplovich, I. B.; Zyablyuk, K. N.
1996-01-01
We calculate the chromoelectric dipole moment (CEDM) of d- and s-quark in the supersymmetric SO(10) model. CEDM is more efficient than quark electric dipole moment (EDM), in inducing the neutron EDM. New, strict constraints on parameters of the supersymmetric SO(10) model follow in this way from the neutron dipole moment experiments. As strict bounds are derived from the upper limits on the dipole moment of odd isotope of mercury.
rp Drell-Yan Process in Color Dipole Model
Institute of Scientific and Technical Information of China (English)
ZHAO Hong-Ming; DUAN Chun-Gui
2002-01-01
We study pion-proton Orp) Drell-Yan (DY) dilepton production in the target rest frame with color dipole model. The prediction for πp DY cross section at the energies of RHIC and LHC is presented, and it can be compared with the data directly, because it does not need K factor. At the same time, the transverse momentum distribution is shown in quantities, which is not available from the standard parton model. The experimental studies of the process could test the color model for DY dilepton production.
Model dependence of the deuteron electric dipole moment
Gibson, B. F.; Afnan, I. R.
2012-09-01
Direct measurement of the electric dipole moment (EDM) of the neutron lies in the future; measurement of a nuclear EDM may well be obtained first. The deuteron is the one nucleus for which exact model calculations can easily be performed. In this report we explore the model dependence of deuteron EDM calculations. Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variations in the nucleon-nucleon interaction, including contemporary potential models. We compare the full calculation with the result in the plane-wave approximation, explore the tensor force contribution to the model results, and examine the effects of short range repulsion that characterizes realistic, contemporary potential models of the deuteron. We find that separable potential model calculations will provide an adequate description of the deuteron EDM until such time as a measurement of better than 10% is achieved.
Field Quality of the Short Superconducting Dipole Models for the LHC
Ang, Z; Sanfilippo, S; Siemko, A; Tommasini, D; Venturini-Delsolaro, W; Walckiers, L
2002-01-01
A full characterization of the magnetic field in warm and cold conditions was performed as a part of the standard test on the LHC 1-m long superconducting dipole models. Furthermore, dedicated measurement campaigns addressed the effect of current cycles and quenches on field quality. Powering and quenches were found to generate characteristic instabilities in the geometric harmonics. Detailed results are presented on this phenomenon, as well as correlations between warm and cold measurements and field reconstructions.
Field quality of the short superconducting dipole models for the LHC
Venturini-Delsolaro, W; Bottura, L; Sanfilippo, S; Siemko, A; Tommasini, D; Walckiers, L
2002-01-01
A full characterization of the magnetic field in warm and cold conditions was performed as a part of the standard test on the LHC 1- m long superconducting dipole models. Furthermore, dedicated measurement campaigns addressed the effect of current cycles and quenches on field quality. Powering and quenches were found to generate characteristic instabilities in the geometric harmonics. Detailed results are presented on this phenomenon, as well as correlations between warm and cold measurements and field reconstructions. (9 refs).
Predictability of the Indian Ocean Dipole in the coupled models
Liu, Huafeng; Tang, Youmin; Chen, Dake; Lian, Tao
2017-03-01
In this study, the Indian Ocean Dipole (IOD) predictability, measured by the Indian Dipole Mode Index (DMI), is comprehensively examined at the seasonal time scale, including its actual prediction skill and potential predictability, using the ENSEMBLES multiple model ensembles and the recently developed information-based theoretical framework of predictability. It was found that all model predictions have useful skill, which is normally defined by the anomaly correlation coefficient larger than 0.5, only at around 2-3 month leads. This is mainly because there are more false alarms in predictions as leading time increases. The DMI predictability has significant seasonal variation, and the predictions whose target seasons are boreal summer (JJA) and autumn (SON) are more reliable than that for other seasons. All of models fail to predict the IOD onset before May and suffer from the winter (DJF) predictability barrier. The potential predictability study indicates that, with the model development and initialization improvement, the prediction of IOD onset is likely to be improved but the winter barrier cannot be overcome. The IOD predictability also has decadal variation, with a high skill during the 1960s and the early 1990s, and a low skill during the early 1970s and early 1980s, which is very consistent with the potential predictability. The main factors controlling the IOD predictability, including its seasonal and decadal variations, are also analyzed in this study.
Transferable Deformation-Dipole Model for Ionic Materials
Karaman, Ali; Akdeniz, Zehra; Tosi, Mario P.
2007-06-01
A model for the ionic interactions in polyvalent metal halides was originally built for chloroaluminate clusters using an analysis of data on static and dynamic structure of their molecular monomers [for a review see M. P. Tosi, Phys. Chem. Liquids 43, 409 (2005)]. Recently, by continuing the deformation-dipole model calculations, the transferability of the halogen parameters was tested through the calculation of the structure of alkali halides and alkaline-earth halides. In this work we test the usefulness of the deformation-dipole model in the study of ionic materials by examining the transferability of the overlap parameters for the halogen ions across families of halide compounds. Following a comparative discussion of alkali and alkaline-earth halide monomers near equilibrium, results on alkaline-earth halides are given. By using the transferable ionic potential model we also calculate the equilibrium structure of the molecular clusters, as well as the vibrational frequencies of ACl4 compounds (where A = U, Np, Pu, Am and Th).
Real-time ECG emulation: a multiple dipole model for electrocardiography simulation.
Abkai, Ciamak; Hesser, Jürgen
2009-01-01
A new model for describing electrocardiography (ECG) is presented, which is based on multiple dipoles compared to standard single dipole approaches in vector electrocardiography. The multiple dipole parameters are derived from real data (e.g. four dipoles from 12-channel ECG) by solving the backward problem of ECG numerically. Results are transformed to a waveform description based on Gaussian mixture for every dimension of each dipole. These compact parameterized descriptors are used for a very realistic real-time simulation applying the forward solution of the proposed model.
Algebraic Reconstruction of Current Dipoles and Quadrupoles in Three-Dimensional Space
Directory of Open Access Journals (Sweden)
Takaaki Nara
2013-01-01
Full Text Available This paper presents an algebraic method for an inverse source problem for the Poisson equation where the source consists of dipoles and quadrupoles. This source model is significant in the magnetoencephalography inverse problem. The proposed method identifies the source parameters directly and algebraically using data without requiring an initial parameter estimate or iterative computation of the forward solution. The obtained parameters could be used for the initial solution in an optimization-based algorithm for further refinement.
Advances in spike localization with EEG dipole modeling.
Rose, Sandra; Ebersole, John S
2009-10-01
EEG interpretation by visual inspection of waveforms, using the assumption that activity at a given electrode is a representation of only the activity of the cortex immediately beneath it, has been the traditional form of EEG analysis since its inception. The relatively recent advent of digital EEG has allowed more advanced analysis of EEG data and has shown that the simple visual inspection described above is a simplistic form of analysis. This is especially true when one is attempting to localize an epileptogenic focus using EEG spikes or seizure onset data. Spatiotemporal analysis of scalp voltage fields has allowed for improved localization of likely cerebral origins of such waveforms. Equivalent dipole source modeling is one such technique and, although not perfect, provides improved characterization of spike and seizure sources as compared to previous methods when properly interpreted. The use of other modern techniques, such as 3D MRI reconstructions and realistic head models, can further improve accuracy of dipole localization and allow for the synthesis of EEG and imaging data, which may be invaluable, especially in cases of pre-surgical epilepsy evaluation.
Coarse predictions of dipole reversals by low-dimensional modeling and data assimilation
Morzfeld, Matthias; Fournier, Alexandre; Hulot, Gauthier
2017-01-01
Low-dimensional models for Earth's magnetic dipole may be a powerful tool for studying large-scale dipole dynamics over geological time scales, where direct numerical simulation remains challenging. We investigate the utility of several low-dimensional models by calibrating them against the signed relative paleointensity over the past 2 million years. Model calibrations are done by "data assimilation" which allows us to incorporate nonlinearity and uncertainty into the computations. We find that the data assimilation is successful, in the sense that a relative error is below 8% for all models and data sets we consider. The successful assimilation of paleomagnetic data into low-dimensional models suggests that, on millennium time scales, the occurrence of dipole reversals mainly depends on the large-scale behavior of the dipole field, and is rather independent of the detailed morphology of the field. This, in turn, suggests that large-scale dynamics of the dipole may be predictable for much longer periods than the detailed morphology of the field, which is predictable for about one century. We explore these ideas and introduce a concept of "coarse predictions", along with a sound numerical framework for computing them, and a series of tests that can be applied to assess their quality. Our predictions make use of low-dimensional models and assimilation of paleomagnetic data and, therefore, rely on the assumption that currently available paleomagnetic data are sufficiently accurate, in particular with respect to the timing of reversals, to allow for coarse predictions of reversals. Under this assumption, we conclude that coarse predictions of dipole reversals are within reach. Specifically, using low-dimensional models and data assimilation enables us to reliably predict a time-window of 4 kyr during which a reversal will occur, without being precise about the timing of the reversal. Indeed, our results lead us to forecast that no reversal of the Earth's magnetic
Neutron Electric Dipole Moment in Two Higgs Doublet Model
Hayashi, T; Matsuda, M; Tanimoto, M; Hayashi, Tkemi; Koide, Yoshio; Matsuda, Masahisa; Tanimoto, Morimitsu
1994-01-01
We study the effect of the "chromo-electric" dipole moment on the electric dipole moment(EDM) of the neutron in the two Higgs doublet model. We systematically investigate the Weinberg's operator $O_{3g}=GG\\t G$ and the operator $O_{qg}=\\bar q\\sigma\\t Gq$, in the cases of $\\tan\\b\\gg 1$, $\\tan\\b\\ll 1$ and $\\tan\\b\\simeq 1$. It is shown that $O_{sg}$ gives the main contribution to the neutron EDM compared to the other operators, and also that the contributions of $O_{ug}$ and $O_{3g}$ cancel out each other. It is pointed out that the inclusion of second lightest neutral Higgs scalar adding to the lightest one is of essential importance to estimate the neutron EDM. The neutron EDM is considerably reduced due to the destructive contribution with each other if the mass difference of the two Higgs scalars is of the order $O(50\\G)$.
Neutron electric dipole moment in the minimal supersymmetric standard model
Inui, T; Sakai, N; Sasaki, T; Inui, T; Mumura, Y; Sakai, N; Sasaki, T
1995-01-01
Neutron electric dipole moment (EDM) due to single quark EDM and to the transition EDM is calculated in the minimal supersymmetric standard model. Assuming that the Cabibbo-Kobayashi-Maskawa matrix at the grand unification scale is the only source of CP violation, complex phases are induced in parameters of soft supersymmetry breaking at low energies. Chargino one-loop diagram is found to give the dominant contribution of the order of 10^{-27}\\sim 10^{-29}\\:e\\cdotcm for quark EDM, assuming the light chargino mass and the universal scalar mass to be 50 GeV and 100 GeV, respectively. Therefore the neutron EDM in this class of model is difficult to measure experimentally. Gluino one-loop diagram also contributes due to the flavor changing gluino coupling. The transition EDM is found to give dominant contributions for certain parameter regions.
Stallinga, Sjoerd; Rieger, Bernd
2012-03-12
We introduce a method for determining the position and orientation of fixed dipole emitters based on a combination of polarimetry and spot shape detection. A key element is an effective Point Spread Function model based on Hermite functions. The model offers a good description of the shape variations with dipole orientation and polarization detection channel, and provides computational advantages over the exact vectorial description of dipole image formation. The realized localization uncertainty is comparable to the free dipole case in which spots are rotationally symmetric and can be well modeled with a Gaussian. This result holds for all dipole orientations, for all practical signal levels, and for defocus values within the depth of focus, implying that the massive localization bias for defocused emitters with tilted dipole axis found with Gaussian spot fitting is eliminated.
Model dependence of the H2 electric dipole moment
Afnan, I. R.; Gibson, B. F.
2010-12-01
Background: Direct measurement of the electric dipole moment (EDM) of the neutron is in the future; measurement of a nuclear EDM may well come first. The deuteron is one nucleus for which exact model calculations are feasible. Purpose: We explore the model dependence of deuteron EDM calculations. Methods: Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variation in the nucleon-nucleon interaction. We write the EDM as the sum of two terms, the first depending on the target wave function with plane-wave intermediate states, and the second depending on intermediate multiple scattering in the 3P1 channel, the latter being sensitive to the off-shell behavior of the 3P1 amplitude. Results: We compare the full calculation with the plane-wave approximation result, examine the tensor force contribution to the model results, and explore the effect of short-range repulsion found in realistic, contemporary potential models of the deuteron. Conclusions: Because one-pion exchange dominates the EDM calculation, separable potential model calculations will provide an adequate description of the H2 EDM until such time as a measurement better than 10% is obtained.
Braking Index of Isolated Pulsars II: A novel two-dipole model of pulsar magnetism
Hamil, Oliver Q; Stone, Jirina R
2016-01-01
The magnetic dipole radiation (MDR) model is currently the best approach we have to explain pulsar radiation. However a most characteristic parameter of the observed radiation, the braking index n$_{\\rm obs}$ shows deviations for all the eight best studied isolated pulsars, from the simple model prediction n$_{\\rm dip}$ = 3. The index depends upon the rotational frequency and its first and second time derivatives, but also on the assumption of that the magnetic dipole moment and inclination angle, and the moment of inertia of the pulsar are constant in time. In a recent paper [Phys. Rev. D 91, 063007 (2015)] we showed conclusively that changes in the moment of inertia with frequency alone, cannot explain the observed braking indices. Possible observational evidence for the magnetic dipole moment migrating away from the rotational axis at a rate $\\dot\\alpha$ $\\sim$ 0.6$^{\\circ}$ per 100 years over the life time of the Crab pulsar has been recently suggested by Lyne et al. In this paper, we explore the MDR mode...
Dipole model analysis of highest precision HERA data, including very low $Q^2$'s
Luszczak, Agnieszka
2016-01-01
We analyse, within a dipole model, the final, inclusive HERA DIS cross section data in the low $x$ region, using fully correlated errors. We show, that these highest precision data are very well described within the dipole model framework starting from $Q^2$ values of 3.5 GeV$^2$ to the highest values of $Q^2 =$ 250 GeV$^2$.
Thermal Analysis of the Fair SIS300 Model Dipole
Sorbi, M.; Alessandria, F.; Bellomo, G.; Fabbricatore, P.; Farinon, S.; Gambardella, U.; Musenich, R.; Volpini, G.
2010-04-01
Design activities, conductor R&D and model coil construction are under way for the development of a curved superconducting dipole for the fast cycled SIS300 synchrotron at FAIR at GSI. The main target is the construction within 2009 of a half-length model magnet (cold mass fully integrated in a horizontal cryostat). This magnet is designed for a maximum central field of 4.5 T in a bore of 100 mm, with a ramp rate of 1 T/s. The magnetic length of the model is 3.9 m with a curvature radius of 66.67 m (27 mm of sagitta). This paper describes the thermal analysis of the magnet, based on the estimated values of the losses in the cold mass. The study has been performed with 2-D finite element codes, both in steady state and transient analysis. The study has been completed with measurements of overall thermal exchange coefficient between the kapton-insulated cables and the supercritical helium, in order to validate the adopted assumptions about the material thermal properties.
MAGNETIC MODELING VS MEASUREMENTS OF THE DIPOLES FOR THE JLAB 10 KW FREE ELECTRON LASER UPGRADE
Energy Technology Data Exchange (ETDEWEB)
David Douglas; Robin Wines; Tom Hiatt; George Biallas; Kenneth Baggett; T.J. Schultheiss; V.A. Christina; J.W. Rathke; A. Smirnov; D. Newsham; Y. Luo; D. Yu
2003-05-01
Magnetic measurements of the six families of dipoles for the infrared Free Electron Laser Upgrade at the Thomas Jefferson National Accelerator Facility (Jlab) are compared to the magnetic models on which their design is based. The magnets were designed in parallel by three organizations. They used ANSYS, Radia or Opera 3D as a 3D magnetic modeling program. Comparison of the discrepancies between model and magnet measurement is presented along with analysis of their potential causes. These dipoles operate in two field ranges. The Injector/ Extractor Dipoles operate around 0.05 T and the Arc Dipoles and Optical Chicane Dipoles operate between 0.22 to 0.71 T. All magnets are required to meet core field and field integral flatness to parts in 104 over their good field region.
Yamanaka, Nodoka
2012-01-01
We evaluate the Barr-Zee type two-loop level contribution to the fermion electric and chromo-electric dipole moments with sfermion loop in R-parity violating supersymmetric models. It is found that the Barr-Zee type fermion dipole moment with sfermion loop acts destructively to the currently known fermion loop contribution, and that it has small effect when the mass of squarks or charged sleptons in the loop is larger than or comparable to that of the sneutrinos, but cannot be neglected if the sneutrinos are much heavier than loop sfermions.
Bulk flows and CMB dipole anisotropy in cosmological void models
Tomita, K
1999-01-01
The observational behavior of spherically symmetric inhomogeneous cosmological models is studied, which consist of inner and outer homogeneous regions connected by a shell or an intermediate self-similar region. It is assumed that the present matter density parameter in the inner region is smaller than that in the outer region, and the present Hubble parameter in the inner region is larger than that in the outer region. Then galaxies in the inner void-like region can be seen to have a bulk motion relative to matter in the outer region, when we observe them at a point O deviated from the center C of the inner region. Their velocity $v_p$ in the CD direction is equal to the difference of two Hubble parameters multiplied by the distance between C and O. It is found also that the velocity $v_d$ corresponding to CMB dipole anisotropy observed at O is by a factor $\\approx 10$ small compared with $v_p$. This behavior of $v_d$ and $v_p$ may explain the puzzling situation of the cosmic flow of cluster galaxies, when t...
Impact-parameter dependent Color Glass Condensate dipole model and new combined HERA data
Rezaeian, Amir H
2013-01-01
The Impact-Parameter dependent Color Glass Condensate (b-CGC) dipole model is based on the Balitsky-Kovchegov non-linear evolution equation and improves the Iancu-Itakura-Munier dipole model by incorporating the impact-parameter dependence of the saturation scale. Here we confront the model to the recently released high precision combined HERA data and obtain its parameters. The b-CGC results are then compared to data at small-x for the structure function, the longitudinal structure function, the charm structure function, exclusive vector meson (J/\\psi, \\phi, \\rho) production and Deeply Virtual Compton Scattering (DVCS). We also compare our results with the Impact-Parameter dependent Saturation model (IP-Sat). We show that most features of inclusive DIS and exclusive diffractive data, including the Q^2, W, |t| and x dependence are correctly reproduced in both models. Nevertheless, the b-CGC and the IP-Sat models give different predictions beyond the current HERA kinematics, namely for the structure functions ...
Shell Model Study on the Proton Pigmy Dipole Resonances in ~(17, 18)Ne
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The proton pygmy dipole resonances (PDRs) in proton rich nuclei 17, 18Ne have been investigated in the framework of interacting shell model. The shell model with the self-consistent Skyrme-Hartree-Fock wave functions has well reproduced
Tamagnone, Michele
2014-01-01
An analytical circuit model able to predict the input impedance of reconfigurable graphene plasmonic dipoles is presented. A suitable definition of plasmonic characteristic impedance, employing natural currents, is used to for consistent modeling of the antenna-load connection in the circuit. In its purely analytical form, the model shows good agreement with full-wave simulations, and explains the remarkable tuning properties of graphene antennas. Furthermore, using a single full-wave simulation and scaling laws, additional parasitic elements can be determined for a vast parametric space, leading to very accurate modeling. Finally, we also show that the modeling approach allows fair estimation of radiation efficiency as well. The approach also applies to thin plasmonic antennas realized using noble metals or semiconductors.
Asner, A
1985-01-01
Compensation of the magnetization current induced sextupole error at LHC injection field by short lumped permanent sextupole magnets, incorporated into the end configuration of superconducting dipoles
Automatic removal of eye movement artifacts from the EEG using ICA and the dipole model
Institute of Scientific and Technical Information of China (English)
Weidong Zhou; Jean Gotman
2009-01-01
12 patients were analyzed.The experimental results indicate that ICA with the dipole model is very efficient at automatically subtracting the eye movement artifacts,while retaining the EEG slow waves and making their interpretation easier.
Dipole model analysis of the new HERA I+II data
Luszczak, Agnieszka
2016-01-01
We use the dipole model to analyze the inclusive DIS cross section data, obtained from the HERA I+II measurements \\cite{Abramowicz:2015mha}. We show that these combined data are very well described within the dipole model framework, which is complemented with a valence quark structure functions. Our motivation is to investigate the gluon density with the BGK dipole model \\cite{BGK} as an alternative to the PDF approach. BGK dipole model uses for evolution the DGLAP mechanism in the $kt$ factorization scheme (in contrast to the collinear factorization for PDFs). We confirm our results from the previous paper \\cite{Luszczak:2013rxa} with old HERA data \\cite{HERA2010}. In addition we also performed a first, preliminary investigation of saturation. The analysis was done in the xFitter framework \\cite{xFitter,xFitter2,xFitter3,xFitter4,xFitter5}.}
Implementation of an offset-dipole magnetic field in a pulsar modelling code
Breed, M; Harding, A K; Johnson, T J
2014-01-01
The light curves of gamma-ray pulsars detected by the Fermi Large Area Telescope show great variety in profile shape and position relative to their radio profiles. Such diversity hints at distinct underlying magnetospheric and/or emission geometries for the individual pulsars. We implemented an offset-dipole magnetic field in an existing geometric pulsar modelling code which already includes static and retarded vacuum dipole fields. In our model, this offset is characterised by a parameter epsilon (with epsilon = 0 corresponding to the static dipole case). We constructed sky maps and light curves for several pulsar parameters and magnetic fields, studying the effect of an offset dipole on the resulting light curves. A standard two-pole caustic emission geometry was used. As an application, we compared our model light curves with Fermi data for the bright Vela pulsar.
An equivalent magnetic dipoles model for quantitative damage recognition of broken wire
Institute of Scientific and Technical Information of China (English)
TAN Ji-wen; ZHAN Wei-xia; LI Chun-jing; WEN Yan; SHU Jie
2005-01-01
By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken wire was presented. The relevant calculation formulas were also deduced. A composite solution method about nonlinear optimization was given. An example was given to illustrate the use of the equivalent magnetic dipoles method for quantitative damage recognition, and demonstrates that the result of this method is consistent with the real situation, so the method is valid and practical.
The neutron electric dipole form factor in the perturbative chiral quark model
Dib, C; Gutsche, T; Kovalenko, S; Kuckei, J; Lyubovitskij, V E; Pumsa-ard, K; Dib, Claudio; Faessler, Amand; Gutsche, Thomas; Kovalenko, Sergey; Kuckei, Jan; Lyubovitskij, Valery E.; Pumsa-ard, Kem
2006-01-01
We calculate the electric dipole form factor of the neutron in a perturbative chiral quark model, parameterizing CP-violation of generic origin by means of effective electric dipole moments of the constituent quarks and their CP-violating couplings to the chiral fields. We discuss the relation of these effective parameters to more fundamental ones such as the intrinsic electric and chromoelectric dipole moments of quarks and the Weinberg parameter. From the existing experimental upper limits on the neutron EDM we derive constraints on these CP-violating parameters.
Pouring concrete to form a model LEP dipole yoke
1979-01-01
The magnetic field needed in the LEP dipole magnets was rather low, of a fraction of tesla. This lead to the conception of a novel yoke structure consisting of stacks of 1.5 mm thick low-carbon steel laminations spaced by 4.1 mm with the spaces filled with concrete. For details see LEP-Note 118,1978 and LEP-Note 233,1980. See also 8111529, 8111710X, 7901023X,7908294
Völlinger, C
2000-01-01
This note presents a scheme for compensating the persistent current multipole errors of the LHC dipoles by making the coil protection sheets from soft magnetic material of 0.5 mm thickness. The material properties assumed in this study are those of iron sheets with a very low content of impurities (99.99% pure Fe). The non-linearities in the upramp cycle on the b3 multipole component can be reduced by the factor of four (while decreasing the b5 variation by the factor of two. Using sheets of slightly different thicknesses offers a tuning possibility for the series magnet coils and can compensate deviations arising from cables of different suppliers. The calculation method is based on a semi-analytical hysteresis model for hard superconductors and an M(B) - iteration using the method of coupled boundary elements - finite elements (BEM - FEM). It is now possible to compute persistent current multipole errors of geometries with arbitrarily shaped iron yokes and thin layers of soft magnetic material such as tunin...
A New Method for Modeling the Coronal Magnetic Field with STEREO and Submerged Dipoles
Sandman, A. W.; Aschwanden, M. J.
2011-06-01
Recent magnetic modeling efforts have shown substantial misalignment between theoretical models and observed coronal loop morphology as observed by STEREO/EUVI, regardless of the type of model used. Both potential field and non-linear force-free field (NLFFF) models yielded overall misalignment angles of 20 - 40 degrees, depending on the complexity of the active region (Sandman et al., Solar Phys. 259, 1, 2009; DeRosa et al., Astrophys. J. 696, 1780, 2009) We demonstrate that with new, alternative forward-fitting techniques, we can achieve a significant reduction in the misalignment angles compared with potential field source surface (PFSS) models and NLFFF models. Fitting a series of submerged dipoles to the field directions of stereoscopically triangulated loops in four active regions (30 April, 9 May, 19 May, and 11 December 2007), we find that 3 - 5 dipoles per active region yield misalignment angles of ˜ 11° - 18°, a factor of two smaller than those given by previously established extrapolation methods. We investigate the spatial and temporal variation of misalignment angles with subsets of loops for each active region, as well as loops observed prior to and following a flare and filament eruption, and find that the spatial variation of median misalignment angles within an active region (up to 75%) exceeds the temporal variation associated with the flare (up to 40%). We also examine estimates of the stereoscopic error of our analysis. The corrected values yield a residual misalignment of 7° - 13°, which is attributed to the non-potentiality due to currents in the active regions.
On the collectivity of Pygmy Dipole Resonance within schematic TDA and RPA models
Baran, V; Colonna, M; Di Toro, M; Croitoru, A; Nicolin, A I
2014-01-01
Within schematic models based on the Tamm-Dancoff Approximation and the Random-Phase Approximation with separable interactions, we investigate the physical conditions which determine the emergence of the Pygmy Dipole Resonance in the E1 response of atomic nuclei. We find that if some particle-hole excitation manifests a different, weaker residual interaction, an additional mode will appear, with an energy centroid closer to the distance between two major shells and therefore well below the Giant Dipole Resonance. This state, together with Giant Dipole Resonance, exhausts all the transition strength in the Tamm-Dancoff Approximation and all the Energy Weighted Sum Rule in the Random-Phase Approximation. These features suggest a collective nature for this mode which we identify with the Pygmy Dipole Resonance.
Radiating dipole model of interference induced in spacecraft circuitry by surface discharges
Metz, R. N.
1984-01-01
Spacecraft in geosynchronous orbit can be charged electrically to high voltages by interaction with the space plasma. Differential charging of spacecraft surfaces leads to arc and blowoff discharging. The discharges are thought to upset interior, computer-level circuitry. In addition to capacitive or electrostatic effects, significant inductive and less significant radiative effects of these discharges exist and can be modeled in a dipole approximation. Flight measurements suggest source frequencies of 5 to 50 MHz. Laboratory tests indicate source current strengths of several amperes. Electrical and magnetic fields at distances of many centimeters from such sources can be as large as tens of volts per meter and meter squared, respectively. Estimates of field attenuation by spacecraft walls and structures suggest that interior fields may be appreciable if electromagnetic shielding is much thinner than about 0.025 mm (1 mil). Pickup of such fields by wires and cables interconnecting circuit components could be a source of interference signals of several volts amplitude.
Dzuba, V A
2010-01-01
We review current status of the study of parity and time invariance phenomena in atoms, nuclei and molecules. We focus on three most promising areas of research: (i) parity non-conservation in a chain of isotopes, (ii) search for nuclear anapole moments, and (iii) search for permanent electric dipole moments (EDM) of atoms and molecules which are caused by either, electron EDM or nuclear $T,P$-odd moments such as nuclear EDM and nuclear Schiff moment.
Testing the axial dipole hypothesis for the Moon by modeling the direction of crustal magnetization
Oliveira, J. S.; Wieczorek, M. A.
2017-02-01
Orbital magnetic field data show that portions of the Moon's crust are strongly magnetized, and paleomagnetic data of lunar samples suggest that Earth strength magnetic fields could have existed during the first several hundred million years of lunar history. The origin of the fields that magnetized the crust are not understood and could be the result of either a long-lived core-generated dynamo or transient fields associated with large impact events. Core dynamo models usually predict that the field would be predominantly dipolar, with the dipole axis aligned with the rotation axis. We test this hypothesis by modeling the direction of crustal magnetization using a global magnetic field model of the Moon derived from Lunar Prospector and Kaguya magnetometer data. We make use of a model that assumes that the crust is unidirectionally magnetized. The intensity of magnetization can vary with the crust, and the best fitting direction of magnetization is obtained from a nonnegative least squares inversion. From the best fitting magnetization direction we obtain the corresponding north magnetic pole predicted by an internal dipolar field. Some of the obtained paleopoles are associated with the current geographic poles, while other well-constrained anomalies have paleopoles at equatorial latitudes, preferentially at 90° east and west longitudes. One plausible hypothesis for this distribution of paleopoles is that the Moon possessed a long-lived dipolar field but that the dipole was not aligned with the rotation axis as a result of large-scale heat flow heterogeneities at the core-mantle boundary.
Modelling the impacts of a dipole-like climatic state over the Arctic
Pasha Karami, Mehdi; de Vernal, Anne; Hu, Xianmin; Myers, Paul G.
2015-04-01
The Arctic dipole anomaly (ADA) features a pattern with opposite sea-level pressure anomalies over the Canadian Archipelago and the Barents Sea. Changes in the predominance of Arctic atmospheric circulation modes and the shift towards a dipole mode in the past decade played a role in the summer sea ice loss and sea ice-freshwater export from the Arctic to the North Atlantic. Reconstruction of sea ice cover variations during Holocene also suggests opposite anomalies in the Barents Sea versus either the western Arctic or the Fram Strait area similar to the ADA pattern. It is vital to study such physical processes that cause dramatic changes in the Arctic sea ice recalling the link between the ADA and the current climate change. Here we focus on the question of how a persistent ADA-like state affects the Arctic sea ice distribution and its outflow to the Atlantic Ocean. For this purpose, an eddy-permitting regional configuration of the NEMO coupled ocean/sea-ice model is used. The regional domain covers the Arctic Ocean and the Northern-Hemisphere Atlantic, with a horizontal resolution of 1/4 degree at the equator (ANHA4). For the present-day simulations, boundary conditions are obtained by taking the average over the years with a positive ADA and those with a negative ADA. In the Holocene scenario, global climate model data are used to force our regional model. To exclude the role of Bering Strait and the heat flux from the Pacific Ocean, we repeat the experiments with a closed Bering Strait since a nearly closed Bering configuration was possible for the Early Holocene. The model results are compared with the paleoclimate data from Arctic and subarctic seas.
A simple stochastic model for dipole moment fluctuations in numerical dynamo simulations
Meduri, Domenico G.; Wicht, Johannes
2016-04-01
Earth's axial dipole field changes in a complex fashion on many different time scales ranging from less than a year to tens of million years. Documenting, analysing, and replicating this intricate signal is a challenge for data acquisition, theoretical interpretation, and dynamo modelling alike. Here we explore whether axial dipole variations can be described by the superposition of a slow deterministic drift and fast stochastic fluctuations, i.e. by a Langevin-type system. The drift term describes the time averaged behaviour of the axial dipole variations, whereas the stochastic part mimics complex flow interactions over convective time scales. The statistical behaviour of the system is described by a Fokker-Planck equation which allows useful predictions, including the average rates of dipole reversals and excursions. We analyse several numerical dynamo simulations, most of which have been integrated particularly long in time, and also the palaeomagnetic model PADM2M which covers the past 2 Myr. The results show that the Langevin description provides a viable statistical model of the axial dipole variations on time scales longer than about 1 kyr. For example, the axial dipole probability distribution and the average reversal rate are successfully predicted. The exception is PADM2M where the stochastic model reversal rate seems too low. The dependence of the drift on the axial dipole moment reveals the nonlinear interactions that establish the dynamo balance. A separate analysis of inductive and diffusive magnetic effects in three dynamo simulations suggests that the classical quadratic quenching of induction predicted by mean-field theory seems at work.
Silva, Arnaldo F; da Silva, João V; Haiduke, R L A; Bruns, Roy E
2011-11-17
Infrared fundamental vibrational intensities and quantum theory atoms in molecules (QTAIM) charge-charge flux-dipole flux (CCFDF) contributions to the polar tensors of the fluorochloromethanes have been calculated at the QCISD/cc-pVTZ level. A root-mean-square error of 20.0 km mol(-1) has been found compared to an experimental error estimate of 14.4 and 21.1 km mol(-1) for MP2/6-311++G(3d,3p) results. The errors in the QCISD polar tensor elements and mean dipole moment derivatives are 0.059 e when compared with the experimental values. Both theoretical levels provide results showing that the dynamical charge and dipole fluxes provide significant contributions to the mean dipole moment derivatives and tend to be of opposite signs canceling one another. Although the experimental mean dipole moment derivative values suggest that all the fluorochloromethane molecules have electronic structures consistent with a simple electronegativity model with transferable atomic charges for their terminal atoms, the QTAIM/CCFDF models confirm this only for the fluoromethanes. Whereas the fluorine atom does not suffer a saturation effect in its capacity to drain electronic charge from carbon atoms that are attached to other fluorine and chlorine atoms, the zero flux electronic charge of the chlorine atom depends on the number and kind of the other substituent atoms. Both the QTAIM carbon charges (r = 0.990) and mean dipole moment derivatives (r = 0.996) are found to obey Siegbahn's potential model for carbon 1s electron ionization energies at the QCISD/cc-pVTZ level. The latter is a consequence of the carbon mean derivatives obeying the electronegativity model and not necessarily to their similarities with atomic charges. Atomic dipole contributions to the neighboring atom electrostatic potentials of the fluorochloromethanes are found to be of comparable size to the atomic charge contributions and increase the accuracy of Siegbahn's model for the QTAIM charge model results
Higo, J; Sasai, M; Shirai, H; Nakamura, H; Kugimiya, T
2001-05-22
We propose a framework to describe the cooperative orientational motions of water molecules in liquid water and around solute molecules in water solutions. From molecular dynamics (MD) simulation a new quantity "site-dipole field" is defined as the averaged orientation of water molecules that pass through each spatial position. In the site-dipole field of bulk water we found large vortex-like structures of more than 10 A in size. Such coherent patterns persist more than 300 ps although the orientational memory of individual molecules is quickly lost. A 1-ns MD simulation of systems consisting of two amino acids shows that the fluctuations of site-dipole field of solvent are pinned around the amino acids, resulting in a stable dipole-bridge between side-chains of amino acids. The dipole-bridge is significantly formed even for the side-chain separation of 14 A, which corresponds to five layers of water. The way that dipole-bridge forms sensitively depends on the side-chain orientations and thereby explains the specificity in the solvent-mediated interactions between biomolecules.
Reversals of the solar magnetic dipole in the light of observational data and simple dynamo models
Moss, D; Sokoloff, D D; Hoeksema, J T
2013-01-01
Observations show that the photospheric solar magnetic dipole usually does not vanish during the inversion of the solar magnetic field, which occurs in each solar cycle. In contrast, mean-field solar dynamo models predict that the dipole field does become zero. In a recent paper Moss et al. (2013) suggested that this contradiction can be explained as a large-scale manifestation of small-scale magnetic fluctuations. Our aim is to confront this interpretation with the available observational data. Here we compare this interpretation with WSO (Wilcox Solar Observatory) photospheric magnetic field data in order to determine the amplitude of magnetic fluctuations required to explain the phenomenon and to compare the results with predictions from a simple dynamo model which takes fluctuations into account. We demonstrate that the WSO data concerning the magnetic dipole inversions are very similar indeed to the predictions of our very simple solar dynamo model, which includes both mean magnetic field and fluctuation...
Coupled-Channel Models of Direct-Semidirect Capture via Giant-Dipole Resonances
Energy Technology Data Exchange (ETDEWEB)
Thompson, I J [Lawrence Livermore National Laboratory (LLNL); Escher, Jutta E [ORNL; Arbanas, Goran [ORNL
2013-01-01
Semidirect capture, a two-step process that excites a giant-dipole resonance followed by its radiative de-excitation, is a dominant process near giant-dipole resonances, that is, for incoming neutron energies within 5 20 MeV. At lower energies such processes may affect neutron capture rates that are relevant to astrophysical nucleosynthesis models. We implement a semidirect capture model in the coupled-channel reaction code Fresco and validate it by comparing the cross section for direct-semidirect capture 208Pb(n,g)209Pb to experimental data. We also investigate the effect of low-energy electric dipole strength in the pygmy resonance. We use a conventional single-particle direct-semidirect capture code Cupido for comparison. Furthermore, we present and discuss our results for direct-semidirect capture reaction 130Sn(n,g)131Sn, the cross section of which is known to have a significant effect on nucleosynthesis models.
The Influence of Train Leakage Currents on the LEP Dipole Field
Bravin, Enrico; Dehning, Bernd; Drees, A; Galbraith, Peter; Geitz, M A; Henrichsen, K N; Koratzinos, M; Mugnai, G
1998-01-01
The determination of the mass and the width of the Z boson at CERN's LEP accelerator, an e+e- storage ring with a circumference of approximately 27 kilometres, imposes heavy demands on the knowledge of the LEP counter-rotating electron and positron beam energies. The precision required is of the order of 1 MeV or »20 ppm frequency. Due to its size the LEP collider is influenced by various macroscopic and regional factors such as the position of the moon or seasonal changes of the rainfall in the area, as reported earlier. A new and not less surprising effect of the LEP energy was observed in 1995: railroad trains in the Geneva region perturb the dipole field. A parasitic flow of electricity, originating from the trains, travels along the LEP ground cable and the vacuum chamber, interacting with the dipole field. An account of the phenomenon with its explanation substantiated by dedicated measurements is presented.
The influence of train leakage currents on the LEP dipole field
Bravin, E.; Brun, G.; Dehning, B.; Drees, A.; Galbraith, P.; Geitz, M.; Henrichsen, K.; Koratzinos, M.; Mugnai, G.; Tonutti, M.
The determination of the mass and the width of the Z boson at CERN's LEP accelerator, an e+e- storage ring with a circumference of approximately 27 km, imposes heavy demands on the knowledge of the LEP counter-rotating electron and positron beam energies. The precision required is of the order of 1 MeV or ≈ 20 ppm. Due to its size, the LEP collider is influenced by various macroscopic and regional factors such as the position of the moon or seasonal changes of the rainfall in the area, as reported earlier. A new and not less surprising effect on the LEP energy was observed in 1995: railroad trains in the Geneva region perturb the dipole field. A parasitic flow of electricity, originating from the trains, travels along the LEP vacuum chamber, affecting the LEP dipole field. An account of the phenomenon with its explanation substantiated by dedicated measurements is presented.
Determination of Deuteron Dipole Moment in Nuclear Quark-Like Model
Institute of Scientific and Technical Information of China (English)
N.Ghahramany; E.Yazdankish
2013-01-01
Using the quark-like model,we have improved the existing deviation between theoretical and experimental values of magnetic dipole moment of deuteron.Based upon Pauli Exclusion Principle,the constituent quarks form a ground state for l =0.The expectation value of the deuteron magnetic dipole moment operator is determined to be equal to 0.861 5978μN in better agreement with the measured value of 0.8574376μN as compared to the shell model calculations.
Stallinga, S.; Rieger, B.
2012-01-01
We introduce a method for determining the position and orientation of fixed dipole emitters based on a combination of polarimetry and spot shape detection. A key element is an effective Point Spread Function model based on Hermite functions. The model offers a good description of the shape variation
Unraveling models of CP violation through electric dipole moments of light nuclei
Dekens, W.; Vries, J. de; Bsaisou, J.; Bernreuther, W.; Hanhart, C.; Meißner, Ulf-G; Nogga, A.; Wirzba, A.
2014-01-01
We show that the proposed measurements of the electric dipole moments of light nuclei in storage rings would put strong constraints on models of flavor-diagonal CP violation. Our analysis is exemplified by a comparison of the Standard Model including the QCD theta term, the minimal left-right symmet
A periodic charge-dipole electrostatic model: parametrization for silver slabs.
Bodrenko, I V; Sierka, M; Fabiano, E; Della Sala, F
2012-10-07
We present an extension of the charge-dipole model for the description of periodic systems. This periodic charge-dipole electrostatic model (PCDEM) allows one to describe the linear response of periodic structures in terms of charge- and dipole-type gaussian basis functions. The long-range electrostatic interaction is efficiently described by means of the continuous fast multipole method. As a first application, the PCDEM method is applied to describe the polarizability of silver slabs. We find that for a correct description of the polarizability of the slabs both charges and dipoles are required. However a continuum set of parametrizations, i.e., different values of the width of charge- and dipole-type gaussians, leads to an equivalent and accurate description of the slabs polarizability but a completely unphysical description of induced charge-density inside the slab. We introduced the integral squared density measure which allows one to obtain a unique parametrization which accurately describes both the polarizability and the induced density profile inside the slab. Finally the limits of the electrostatic approximations are also pointed out.
Modeling of the Voltage Waves in the LHC Main Dipole Circuits
Ravaioli, E; Formenti, F; Steckert, J; Thiesen, H; Verweij, A
2012-01-01
When a fast power abort is triggered in the LHC main dipole chain, voltage transients are generated at the output of the power converter and across the energy-extraction switches. The voltage waves propagate through the chain of 154 superconducting dipoles and can have undesired effects leading to spurious triggering of the quench protection system and firing of the quench heaters. The phase velocity of the waves travelling along the chain changes due to the inhomogeneous AC behavior of the dipoles. Furthermore, complex phenomena of reflection and superposition are present in the circuit. For these reasons analytical calculations are not sufficient for properly analyzing the circuit behavior after a fast power abort. The transients following the switch-off of the power converter and the opening of the switches are analyzed by means of a complete electrical model, developed with the Cadence© suite (PSpice© based). The model comprises all the electrical components of the circuit, additional components simula...
Morzfeld, M.; Fournier, A.; Hulot, G.
2014-12-01
We investigate the geophysical relevance of low-dimensional models of the geomagnetic dipole fieldby comparing these models to the signed relative paleomagnetic intensity over the past 2 Myr.The comparison is done via Bayesian statistics, implemented numerically by Monte Carlo (MC) sampling.We consider several MC schemes, as well as two data sets to show the robustness of our approach with respect to its numerical implementation and to the details of how the data are collected.The data we consider are the Sint-2000 [1] and PADM2M [2] data sets.We consider three stochastic differential equation (SDE) models and one deterministic model. Experiments with synthetic data show that it is feasible that a low dimensional modelcan learn the geophysical state from data of only the dipole field,and reveal the limitations of the low-dimensional models.For example, the G12 model [3] (a deterministic model that generates dipole reversals by crisis induced intermittency)can only match either one of the two important time scales we find in the data. The MC sampling approach also allows usto use the models to make predictions of the dipole field.We assess how reliably dipole reversals can be predictedwith our approach by hind-casting five reversals documented over the past 2 Myr. We find that, besides its limitations, G12 can be used to predict reversals reliably,however only with short lead times and over short horizons. The scalar SDE models on the other hand are not useful for prediction of dipole reversals.References Valet, J.P., Maynadier,L and Guyodo, Y., 2005, Geomagnetic field strength and reversal rate over the past 2 Million years, Nature, 435, 802-805. Ziegler, L.B., Constable, C.G., Johnson, C.L. and Tauxe, L., 2011, PADM2M: a penalized maximum likelihood model of the 0-2 Ma paleomagnetic axial dipole moment, Geophysical Journal International, 184, 1069-1089. Gissinger, C., 2012, A new deterministic model for chaotic reversals, European Physical Journal B, 85:137.
DEFF Research Database (Denmark)
Archilla, J. F.R.; Christiansen, Peter Leth; Gaididei, Yuri Borisovich
2002-01-01
Most of the studies on mathematical models of DNA are limited to next neighbor interaction. However, the coupling between base pairs is thought to be caused by dipole interaction, and, when the DNA strand is bent, the distances between base pairs become shorter, therefore the interactions with di...
A simple stochastic model for dipole moment fluctuations in numerical dynamo simulations
Directory of Open Access Journals (Sweden)
Domenico G. eMeduri
2016-04-01
Full Text Available Earth's axial dipole field changes in a complex fashion on many differenttime scales ranging from less than a year to tens of million years.Documenting, analysing, and replicating this intricate signalis a challenge for data acquisition, theoretical interpretation,and dynamo modelling alike. Here we explore whether axial dipole variationscan be described by the superposition of a slow deterministic driftand fast stochastic fluctuations, i.e. by a Langevin-type system.The drift term describes the time averaged behaviour of the axial dipole variations,whereas the stochastic part mimics complex flow interactions over convective time scales.The statistical behaviour of the system is described by a Fokker-Planck equation whichallows useful predictions, including the average rates of dipole reversals and excursions.We analyse several numerical dynamo simulations, most of which havebeen integrated particularly long in time, and also the palaeomagneticmodel PADM2M which covers the past 2 Myr.The results show that the Langevin description provides a viable statistical modelof the axial dipole variations on time scales longer than about 1 kyr.For example, the axial dipole probability distribution and the average reversalrate are successfully predicted.The exception is PADM2M where the stochastic model reversal rate seems too low.The dependence of the drift on the axial dipolemoment reveals the nonlinear interactions that establish thedynamo balance. A separate analysis of inductive and diffusive magnetic effectsin three dynamo simulations suggests that the classical quadraticquenching of induction predicted by mean-field theory seems at work.
Top Quark Chromomagnetic Dipole Moment in the Littlest Higgs Model with T-Parity
Institute of Scientific and Technical Information of China (English)
YUE Chong-Xing; LI Ding
2008-01-01
The littlest Higgs model with T-parity, which is called LHT model, predicts the existence of the new particles, such as heavy top quarks, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark chromomagnetic dipole moment (CMDM) △K. We find that the contribution of the LHT model is one order of magnitude smaller than the standard model prediction value.
Analysis of the variability of the axial dipole moment of a numerical geodynamo model
Kuipers, J.; Hoyng, P.; Wicht, J.; Barkema, G.T.
2009-01-01
We have analysed the time evolution of the axial dipole moments (ADMs) from three numerical geodynamo models by relating it to the Fokker–Planck equation governing the systematic and random ADM motion. We have determined the effective growth rate of the ADM and the diffusion coefficient D characteri
Jensen, L; Astrand, PO; Mikkelsen, KV
An atomic dipole interaction model has been used for calculating the second hyperpolarizability of carbon nanotubes on a length scale up to 75 nm. It is demonstrated that an atomistic representation of mesoscale systems such as nanotubes can be used to obtain a cubic response property up to a size
Atomic Dipole Squeezing in the Correlated Two-Mode Two-Photon Jaynes-Cummings Model
Dong, Zhengchao; Zhao, Yonglin
1996-01-01
In this paper, we study the atomic dipole squeezing in the correlated two-mode two-photon JC model with the field initially in the correlated two-mode SU(1,1) coherent state. The effects of detuning, field intensity and number difference between the two field modes are investigated through numerical calculation.
Smalø, Hans S.; Åstrand, Per-Olof; Mayer, Alexandre
2013-07-01
A molecular mechanics model for the frequency-dependent polarisability is presented. It is a combination of a recent model for the frequency dependence in a charge-dipole model [Nanotechnology 19, 025203, 2008] and a nonmetallic modification of the electronegativity equalisation model rephrased as atom-atom charge-transfer terms [J. Chem. Phys. 131, 044101, 2009]. An accurate model for the frequency-dependent polarisability requires a more accurate partitioning into charge and dipole contributions than the static polarisability, which has resulted in several modifications of the charge-transfer model. Results are presented for hydrocarbons, including among others, alkanes, polyenes and aromatic systems. Although their responses to an electric field are quite different in terms of the importance of charge-transfer contributions, it is demonstrated that their frequency-dependent polarisabilities can be described with the same model and the same set of atom-type parameters.
Haroon, Amir; Mogilatov, Vladimir; Goldman, Mark; Bergers, Rainer; Tezkan, Bülent
2016-05-01
Two novel transient controlled source electromagnetic methods called circular electrical dipole (CED) and differential electrical dipole (DED) are theoretically analysed for applications in shallow marine environments. 1-D and 3-D time-domain modelling studies are used to investigate the detectability and applicability of the methods when investigating resistive layers/targets representing hydrocarbon-saturated formations. The results are compared to the conventional time-domain horizontal electrical dipole (HED) and vertical electrical dipole (VED) sources. The applied theoretical modelling studies demonstrate that CED and DED have higher signal detectability towards resistive targets compared to TD-CSEM, but demonstrate significantly poorer signal amplitudes. Future CED/DED applications will have to solve this issue prior to measuring. Furthermore, the two novel methods have very similar detectability characteristics towards 3-D resistive targets embedded in marine sediments as VED while being less susceptible towards non-verticality. Due to the complex transmitter design of CED/DED the systems are prone to geometrical errors. Modelling studies show that even small transmitter inaccuracies have strong effects on the signal characteristics of CED making an actual marine application difficult at the present time. In contrast, the DED signal is less affected by geometrical errors in comparison to CED and may therefore be more adequate for marine applications.
Electric dipole moments of nucleons, nuclei, and atoms: The Standard Model and beyond
Engel, Jonathan; Ramsey-Musolf, Michael J.; van Kolck, U.
2013-07-01
Searches for the permanent electric dipole moments (EDMs) of molecules, atoms, nucleons and nuclei provide powerful probes of CP violation both within the Standard Model and beyond the Standard Model (BSM). The interpretation of experimental EDM limits requires careful delineation of physics at a wide range of scales, from the long-range atomic and molecular scales to the short-distance dynamics of physics at or beyond the Fermi scale. In this review, we provide a framework for disentangling contributions from physics at these disparate scales, building out from the set of dimension four and six effective operators that embody CP violation at the Fermi scale. We survey computations of hadronic and nuclear matrix elements associated with Fermi-scale CP violation in systems of experimental interest and quantify the present level of theoretical uncertainty in these calculations. Using representative BSM scenarios of current interest, we discuss ways in which the interplay of physics at various scales can generate EDMs at a potentially observable level.
Development of a single-layer Nb3Sn common coil dipole model
Energy Technology Data Exchange (ETDEWEB)
Igor Novitski et al.
2002-12-13
A high-field dipole magnet based on the common coil design was developed at Fermilab for a future Very Large Hadron Collider. A short model of this magnet with a design field of 11 T in two 40-mm apertures is being fabricated using the react-and-wind technique. In order to study and optimize the magnet design two 165-mm long mechanical models were assembled and tested. A technological model consisting of magnet straight section and ends was also fabricated in order to check the tooling and the winding and assembly procedures. This paper describes the design and technology of the common coil dipole magnet and summarizes the status of short model fabrication.The results of the mechanical model tests and comparison with FE mechanical analysis are also presented.
Comment on 'The new F{sub L} measurement from HERA and the dipole model'
Energy Technology Data Exchange (ETDEWEB)
Schildknecht, Dieter, E-mail: schild@physik.uni-bielefeld.de [Fakultaet fuer Physik, Universitaet Bielefeld, D-33501 Bielefeld (Germany); Max-Planck Institute fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, D-80805, Muenchen (Germany)
2012-10-02
The upper bound on the ratio of the proton structure functions F{sub L}/F{sub 2} tested in the recent paper 'The new F{sub L} measurement from HERA and the dipole model', contrary to what is said therein, does not provide a model-independent 'rigorous' experimental test of the color-dipole picture. The validity of the theoretical upper bound depends on an ad hoc assumption on the dipole cross section. The analysis of the experimental data in the paper 'The new F{sub L} measurement from HERA and the dipole model' can be reinterpreted as an additional confirmation of the absolute model-independent prediction from the color-dipole picture of F{sub L}=0.27F{sub 2} at large Q{sup 2}.
Design, Manufacture and Test of a 1.3 T / 10 Hz dipole model for Rapid Cycling Synchrotrons
Newborough, A
2013-01-01
The construction of a compact rapid cycling synchrotron has recently been studied at CERN to replace the first stage of its accelerator complex, the proton synchrotron booster. Although currently there are no plans to build this machine, fast cycled accelerator magnets are of general interest for numerous reasons. This has led to the design, manufacture and testing of a scaled model dipole as detailed in this paper to show the capability of producing and characterising a magnet design based on high-silicon content grain-oriented steel able to operate up to 1.3 T at 10 Hz.
Modeling relaxor characteristics in systems of interacting dipoles
Energy Technology Data Exchange (ETDEWEB)
Kliem, Herbert; Leschhorn, Andreas, E-mail: a.leschhorn@mx.uni-saarland.de
2016-12-15
We present a model which derives typical relaxor characteristics from simple and plausible microscopic assumptions. The model is based on charges which fluctuate thermally activated in double well potentials. The double well potentials are asymmetric due to disorder in the system. The electrostatic interaction between the charges is considered via a mean field approach. This model yields the typical relaxor features: we find high susceptibilities in a broad temperature range with dynamics following the Vogel–Fulcher law. In the framework of the model no spontaneous polarization arises at cooling without strong external field in accordance to experimental findings for relaxors. Furthermore the model yields hysteresis loops which depend on the amplitude of the external field and which become more and more thin and deformed above the maximum temperature of the susceptibility.
Angst, Sebastian; Engelke, Lukas; Winterer, Markus; Wolf, Dietrich E.
2017-06-01
Densification of (semi-)conducting particle agglomerates with the help of an electrical current is much faster and more energy efficient than traditional thermal sintering or powder compression. Therefore, this method becomes more and more common among experimentalists, engineers, and in industry. The mechanisms at work at the particle scale are highly complex because of the mutual feedback between current and pore structure. This paper extends previous modelling approaches in order to study mixtures of particles of two different materials. In addition to the delivery of Joule heat throughout the sample, especially in current bottlenecks, thermoelectric effects must be taken into account. They lead to segregation or spatial correlations in the particle arrangement. Various model extensions are possible and will be discussed.
Dipole moments of the tau neutrino via the process + - → $ \\bar{} $ in a 331 model
Indian Academy of Sciences (India)
A Gutiérrz-Rodríguez
2012-10-01
The limits on the anomalous magnetic and electric dipole moments of the through the reaction + - → $ \\bar{} $ at the 1-pole, and in the framework of a 331 model are obtained. The results are based on the data reported by the L3 Collaboration at LEP. We find that the bounds are almost independent of the mixing angle of the model in the allowed range for this parameter.
Shell model estimate of electric dipole moments in medium and heavy nuclei
Teruya, E.; Yoshinaga, N.; Higashiyama, K.
2014-03-01
It is evidence for an extension of the Standard Model in particle physics, if static electric dipole moments (EDMs) are measured for any elementary particle. The nuclear EDM arises mainly from two sources: one comes from asymmetric charge distribution in a nucleus and the other is due to the nucleon intrinsic EDM. We estimate the nuclear EDMs from two sources for the 1/21+ states in Xe isotopes by a shell model approach using full orbitals between magic numbers 50 and 82.
Schwerg, N
2006-01-01
A new fit function for the critical current density of superconducting NbTi cables for the LHC main dipoles is presented. Existing fit functions usually show a good matching of the very low field range, but produce a current density which is significantly too small for the intermediate and high field range. Consequently the multipole range measured at cold is only partially reproduced and loops from current cycling do not match. The presented function is used as input for the field quality calculation of a complete magnet cross-section including arbitrary current cycling and all hysteresis effects. This way allows to trace a so-called finger-print of the cable combination used in the LHC main bending magnets. The finger-print pattern is a consequence of the differences of the measured superconductor magnetization of cables from different manufacturers. The simulation results have been compared with measurements at cold obtained from LHC main dipoles and a very good agreement for low and intermediate field val...
Lin, Yi-Sheng; Yeh, Bo-Liang; Tsai, Min-Ruei; Cheng, Horng-Long; Liu, Shyh-Jiun; Tang, Fu-Ching; Chou, Wei-Yang
2015-03-01
We describe an unusual phenomenon of time-dependent current growth in organic transistors, particularly n-type transistors. For an organic transistor based on N,N-ditridecyl-3,4,9,10-perylene tetracarboxylic diimide with a polyimide dielectric layer, the time-dependent increase in the drain current and an approximately hysteresis-free electricity were obtained under dc-bias stress. These phenomena could be attributed to (a) reduction in the trap-state density located at the interface between polyimide and semiconductor, (b) gate field effect enhanced by electric dipoles within polyimide, and (c) a low interface trap lifetime. This study reveals that polymer dielectrics with moderate polar groups are suitable for application in stable organic devices.
Richer, E.; Modolo, R.; Chanteur, G. M.; Hess, S.; Leblanc, F.
2012-10-01
The interaction of the solar wind (SW) with the magnetic field of Mercury is investigated by means of a three dimensional parallelized multispecies hybrid model. A comparison between two mathematical representations of Mercury's intrinsic magnetic field is studied. The first model is an Offset Dipole (OD) having the offset and dipolar moment reported by Anderson et al. (2011). The second model is a combination of a Dipole and a Quadrupole (DQ), the total field is fitted to the offset dipolar field, for northern latitudes greater than 50°. Simulations reproduce the features which characterize Mercury's interaction with the SW, encompassing the Bow Shock (BS), the magnetosheath, the magnetotail, the “cusps” region and the neutral current sheet. Global hybrid simulations of the Hermean magnetosphere run for the OD and DQ models demonstrate that the southern parts of the magnetospheres produced by the OD and DQ models differ greatly in topology and volume meanwhile their northern parts-are quite similar. In particular the DQ model exhibits a dome of closed field lines around the south pole in contrast to the OD. Without further information on the intrinsic magnetic field of the planet in the southern region which should be provided by BepiColombo after year 2020, we can only speculate on the influence of the different magnetic topologies on the magnetospheric dynamics.
Tests for, origins of, and corrections to non-Gaussian statistics. The dipole-flip model.
Schile, Addison J; Thompson, Ward H
2017-04-21
Linear response approximations are central to our understanding and simulations of nonequilibrium statistical mechanics. Despite the success of these approaches in predicting nonequilibrium dynamics, open questions remain. Laird and Thompson [J. Chem. Phys. 126, 211104 (2007)] previously formalized, in the context of solvation dynamics, the connection between the static linear-response approximation and the assumption of Gaussian statistics. The Gaussian statistics perspective is useful in understanding why linear response approximations are still accurate for perturbations much larger than thermal energies. In this paper, we use this approach to address three outstanding issues in the context of the "dipole-flip" model, which is known to exhibit nonlinear response. First, we demonstrate how non-Gaussian statistics can be predicted from purely equilibrium molecular dynamics (MD) simulations (i.e., without resort to a full nonequilibrium MD as is the current practice). Second, we show that the Gaussian statistics approximation may also be used to identify the physical origins of nonlinear response residing in a small number of coordinates. Third, we explore an approach for correcting the Gaussian statistics approximation for nonlinear response effects using the same equilibrium simulation. The results are discussed in the context of several other examples of nonlinear responses throughout the literature.
Gaitan, R; de Oca, J H Montes; Martinez, R
2015-01-01
In this work we study the anomalous top quark-gluon couplings Chromoelectric and Chromomagnetic Dipole Moments, CEDM and CMDM, in a general THDM with CP violation. We find that this model provides an important contribution from the $Y_{tt}$ Yukawa coupling that needs to be taken into account. The CMDM and CEDM obtained are $\\Delta\\tilde{k} < 10^{-2}$ and $\\Delta \\tilde{d} < 10^{-4}$.
Neutron electric dipole moment in the minimal 3-3-1 model
De Conto, G
2016-01-01
We calculate the electric dipole moment (EDM) for the neutron in the framework of the minimal 3-3-1 model. We assume that the only source of $CP$ violation arises from a complex trilinear coupling constant and two complex vacuum expectation values. However, from the constraint equations obtained from the potential, only one physical phase remains. We find some constraints on the possible values of this phase and masses of the exotic particles.
Energy Technology Data Exchange (ETDEWEB)
Arroyo-Urena, M.A.; Tavares-Velasco, G. [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico-Matematicas, Puebla, PUE (Mexico); Hernandez-Tome, G. [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico-Matematicas, Puebla, PUE (Mexico); Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Departamento de Fisica, Mexico City (Mexico)
2017-04-15
We obtain analytical expressions, both in terms of parametric integrals and Passarino-Veltman scalar functions, for the one-loop contributions to the anomalous weak magnetic dipole moment (AWMDM) of a charged lepton in the framework of the simplest little Higgs model (SLHM). Our results are general and can be useful to compute the weak properties of a charged lepton in other extensions of the standard model (SM). As a by-product we obtain generic contributions to the anomalous magnetic dipole moment (AMDM), which agree with previous results. We then study numerically the potential contributions from this model to the τ lepton AMDM and AWMDM for values of the parameter space consistent with current experimental data. It is found that they depend mainly on the energy scale f at which the global symmetry is broken and the t{sub β} parameter, whereas there is little sensitivity to a mild change in the values of other parameters of the model. While the τ AMDM is of the order of 10{sup -9}, the real (imaginary) part of its AWMDM is of the order of 10{sup -9} (10{sup -10}). These values seem to be out of the reach of the expected experimental sensitivity of future experiments. (orig.)
A New Hermean Magnetic Field Model using a Modified Equivalent Source Dipole Method
Oliveira, Joana S.; Langlais, Benoit; Pais, M. Alexandra; Amit, Hagay; Thébault, Erwan
2017-04-01
Mercury is the only terrestrial planet, besides the Earth, that has a core dynamo which generates a global magnetic field. MESSENGER orbited Mercury from 2011 to 2015 and provided magnetic measurements which convey crucial information on the magnetic field environment of the planet. We use a local method based on Equivalent Source Dipole approach to model the internal field of Mercury. The method is especially well suited when measurements cover a limited fraction of the planet's surface. Dipoles are placed deep into the planet. Note that with this modeling scheme, we do not attempt to explicitly model the external field. As the planet is in spin-orbit resonance completing three sidereal days in two years, it takes three sidereal days (one solar day) for the Sun to cover all local longitudes. We therefore consider successive periods of one solar day. A dominantly axisymmetric field is found for each solar-day model showing a significant temporal variability. This could be due to some large-scale external field that appears as internal with respect to the spacecraft orbit. The changing altitude and latitude coverage of each model may also be invoked for this variability. We finally compute a 8-solar-day model, including all solar days during the MESSENGER mission, to describe the Hermean magnetic field. Maps of the field computed at 200 km altitude show a magnetic equator at 16°N latitude, and confirm the large-scale and close-to-axisymmetry structure of the internal magnetic field of Mercury. Our model is also in agreement with the magnetic equator crossings detected before. However, our magnetic equator latitude varies with the altitude to the planet. This is indicative that the dipole-offset hypothesis is over-simplified, and that dynamo modelers have to consider alternative models when attempting to model the Hermean dynamo.
LFV and Dipole Moments in Models with A4 Flavour Symmetry
Merlo, Luca
2009-01-01
It is presented an analysis on lepton flavour violating transitions, leptonic magnetic dipole moments and electric dipole moments in a class of models characterized by the flavour symmetry A4 x Z3 x U(1)_FN, whose choice is motivated by the approximate Tri-Bimaximal mixing observed in neutrino oscillations. A low-energy effective Lagrangian is constructed, where these effects are dominated by dimension six operators, suppressed by the scale M of new physics. All the flavour breaking effects are universally described by the vacuum expectation values of a set of spurions. Two separate cases, a supersymmetric and a general one, are described. An upper limit on the reactor angle of a few percent is concluded.
Experimental modelling of the dipole magnet for the electron storage ring DELSY
Meshkov, I N; Syresin, E M
2003-01-01
In the Joint Institute for Nuclear Research (Dubna) the project of Dubna Electron Synchrotron (DELSY) with an electron energy of 1.2 GeV is developed. The electron storage ring in the DELSY project is planned to be created on the basis of magnetic elements, which were used earlier in the storage ring AmPS (NIKHEF, Amsterdam). The optics of the ring is necessary to be changed, its perimeter to be reduced approximately in one and a half time, the energy of electrons to be increased. The paper is devoted to the development of a modified dipole magnet of the storage ring. The preliminary estimation of geometry of the magnet pole is carried out by means of computer modelling using two- and three- dimensional codes of the magnetic field calculation SUPERFISH and RADIA. The experimental stand for the measurements of the dipole magnetic field is described. As the result of calculational and experimental modelling for the dipole magnet, the geometry of its poles was estimated, providing in the horizontal aperture +- 3...
Directory of Open Access Journals (Sweden)
Trullàs J.
2011-05-01
Full Text Available Molecular dynamics simulations of molten NaI at 995 K have been carried out using polarizable ion models based on rigid ion pair potentials to which the anion induced dipole polarization is added. The polarization is added in such a way that point dipoles are induced on the anions by both local electric field and deformation short-range damping interactions that oppose the electrically induced dipole moments. The structure and self-diffusion results are compared with those obtained by Galamba and Costa Cabral using first principles Hellmann-Feynman molecular dynamics simulations and using classical molecular dynamics of a shell model which allows only the iodide polarization
Many-body dispersion interactions from the exchange-hole dipole moment model.
Otero-de-la-Roza, A; Johnson, Erin R
2013-02-07
In this article, we present the extension of the exchange-hole dipole moment model (XDM) of dispersion interactions to the calculation of two-body and three-body dispersion energy terms to any order, 2(l)-pole oscillator strengths, and polarizabilities. By using the newly-formulated coefficients, we study the relative importance of the higher-order two-body and the leading non-additive three-body (triple-dipole) interactions in gas-phase as well as in condensed systems. We show that the two-body terms up to R(-10), but not the terms of higher-order, are essential in the correct description of the dispersion energy, while there are a number of difficulties related to the choice of the damping function, which precludes the use three-body triple-dipole contributions in XDM. We conclude that further study is required before the three-body term can be used in production XDM density-functional calculations and point out the salient problems regarding its use.
Shell model estimate of electric dipole moments in medium and heavy nuclei
Directory of Open Access Journals (Sweden)
Teruya E.
2014-03-01
Full Text Available It is evidence for an extension of the Standard Model in particle physics, if static electric dipole moments (EDMs are measured for any elementary particle. The nuclear EDM arises mainly from two sources: one comes from asymmetric charge distribution in a nucleus and the other is due to the nucleon intrinsic EDM. We estimate the nuclear EDMs from two sources for the 1/21+ states in Xe isotopes by a shell model approach using full orbitals between magic numbers 50 and 82.
Gómez-Dumm, D; Gomez-Dumm, Daniel
1999-01-01
The electric and weak electric dipole form factors for heavy fermions are calculated in the context of the most general two-Higgs-doublet model (2HDM). We find that the large top mass can produce a significant enhancement of the electric dipole form factor in the case of the b and c quarks. This effect can be used to distinguish between different 2HDM scenarios.
Energy Technology Data Exchange (ETDEWEB)
Ige, O.O.; Lyon, R.H.; Iwasa, Y. (Francis Bitter National Magnet Laboratory Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States))
1992-03-15
The longitudinal attenuation of impact-generated pulses in ten superconducting dipole magnets was measured at room temperature. A lumped-parameter model was constructed for the collared dipole. Using the method of nonlinear least-squares, the model was used to estimate the internal damping in the main components of the dipoles and the coupling resistances between the components: collars, inner, and outer coils. A positive correlation was found between the collar-inner coil coupling resistance and the 4.2-K performance of the magnets: the higher the coupling resistance, the fewer the number of quenches required to reach design operating current. There was virtually no correlation between any of the other internal or coupling resistances and 4.2-K performance. These observations are explained in terms of frictional slip of the inner coil against the collars causing premature quenches. The magnets are more susceptible to quenches at the collar-inner coil interface than at the collar-outer coil interface because the inner coil is subject to higher fields and forces. The experiment is potentially useful as a technique for screening high-performance superconducting magnets such as Superconducting Super Collider (SSC) dipoles at room temperature.
Design of the EuCARD High-Field Model Dipole Magnet FRESCA2
Milanese, A; Durante, M; Manil, P; Perez, J C; Rifflet, J M; de Rijk, G; Rondeaux, F
2012-01-01
This paper reports on the design of FRESCA2, a dipole magnet model wound with Nb3Sn Rutherford cable. This magnet is one of the deliverables of the High Field Magnets work package of the European FP7-EuCARD project. The nominal magnetic flux density of 13 Tesla in a 100 mm bore will make it suitable for upgrading the FRESCA cable test facility at CERN. The magnetic layout is based on a block coil, with four layers per pole. The mechanical structure is designed to provide adequate pre-stress, through the use of bladders, keys and an aluminum alloy shrinking cylinder.
Development of the 11 T $Nb_{3}Sn$ dipole model at Fermilab
Ambrosio, G; Arkan, T T; Barzi, E; Caspi, S; Chichili, D R; Chow, K; Kashikhin, V V; Limon, P J; Makarov, A A; Ozelis, J P; Terechkine, Yu; Tompkins, J C; Wake, M; Yadav, S; Yamada, R; Yarba, V A; Zlobin, A V
2000-01-01
A one meter long Nb/sub 3/Sn dipole model with 11 T nominal magnetic field in a 43.5 mm bore is being developed at Fermilab in collaboration with LBNL and KEK as part of the R&D efforts for a future Very Large Hadron Collider. This paper describes the magnet design and fabrication procedure as well as summarizes the results of magnetic, mechanical and quench protection analyses. The main parameters of superconducting strand and cable are also reported. (12 refs).
Shell model estimate of electric dipole moments in medium and heavy nuclei
Teruya, Eri; Yoshinaga, Naotaka; Higashiyama, Koji
2015-05-01
Existence of the electric dipole moment (EDM) is deeply related with time-reversal invariance. The EDMof a diamagnetic atom is mainly induced by the nuclear Schiff moment. After carrying out the shell model calculations to obtain wavefunctions for Xe isotopes, we evaluate nuclear Schiff moments for Xe isotopes to estimate their atomic EDMs. We estimate the contribution from each single particle orbital for the Schiff moment. It is found that the contribution on the Schiff moment is very different from orbital to orbital.
Shell model estimate of electric dipole moments in medium and heavy nuclei
Directory of Open Access Journals (Sweden)
Teruya Eri
2015-01-01
Full Text Available Existence of the electric dipole moment (EDM is deeply related with time-reversal invariance. The EDMof a diamagnetic atom is mainly induced by the nuclear Schiff moment. After carrying out the shell model calculations to obtain wavefunctions for Xe isotopes, we evaluate nuclear Schiff moments for Xe isotopes to estimate their atomic EDMs. We estimate the contribution from each single particle orbital for the Schiff moment. It is found that the contribution on the Schiff moment is very different from orbital to orbital.
Study of the linked dipole chain model in heavy quark production at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Lipatov, Artem V. [Physical Department, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)]. E-mail: lipatov@theory.sinp.msu.ru; Leif Loennblad [Dept. of Theoretical Physics, Lund (Sweden)]. E-mail: Leif.Lonnblad@thep.lu.se; Zotov, Nikolai P. [D.V. Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)]. E-mail: zotov@theory.sinp.msu.ru
2004-01-01
We present calculations of charm and beauty production at Tevatron within the framework of k{sub T} -factorization, using the unintegrated gluon distributions as obtained from the Linked Dipole Chain model. The analysis covers transverse momentum and rapidity distributions and the azimuthal correlations between b and b-bar quarks (or rather muons from their decay) which are powerful tests for the different unintegrated gluon distributions. We compare the theoretical results with recent experimental data taken by D{phi} and CDF collaborations at the Tevatron Run I and II. (author)
Saturn's Magnetic Field Model: Birotor Dipole From Cassini RPWS and MAG Experiments
Galopeau, P. H. M.
2016-12-01
The radio and plasma wave science (RPWS) experiment on board the Cassini spacecraft, orbiting around Saturn since July 2004, revealed the presence of two distinct and variable rotation periods in the Saturnian kilometric radiation (SKR) which were attributed to the northern and southern hemispheres respectively. We believe that the periodic time modulations present in the SKR are mainly due to the rotation of Saturn's inner magnetic field. The existence of a double period implies that the inner field is not only limited to a simple rotation dipole but displays more complex structures having the same time periodicities than the radio emission. In order to build a model of this complex magnetic field, it is absolutely necessary to know the accurate phases of rotation linked with the two periods. The radio observations from the RPWS experiment allow a continuous and accurate follow-up of these rotation phases, since the SKR emission is permanently observable and produced very close to the planetary surface. A wavelet transform analysis of the intensity of the SKR signal received at 290 kHz between July 2004 and June 2012 was performed in order to calculate in the same time the different periodicities and phases. A dipole model was proposed for Saturn's inner magnetic field: this dipole presents the particularity to have North and South poles rotating around Saturn's axis at two different angular velocities; this dipole is tilted and not centered. 57 Cassini's revolutions, the periapsis of which is less than 5 Saturnian radii, have been selected for this study. For each of these chosen orbits, it is possible to fit with high precision the measurements of the MAG data experiment given by the magnetometers embarked on board Cassini. A nonrotating external magnetic field completes the model. This study suggests that Saturn's inner magnetic field is neither stationary nor fully axisymmetric. These results can be used as a boundary condition for modelling and constraining
Energy-dependent dipole form factor in a QCD-inspired model
Bahia, C A S; Luna, E G S
2015-01-01
We consider the effect of an energy-dependent dipole form factor in the high-energy behavior of the forward amplitude. The connection between the semihard parton-level dynamics and the hadron-hadron scattering is established by an eikonal QCD-based model. Our results for the proton-proton ($pp$) and antiproton-proton ($\\bar{p}p$) total cross sections, $\\sigma_{tot}^{pp,\\bar{p}p}(s)$, obtained using the CTEQ6L1 parton distribution function, are consistent with the recent data from the TOTEM experiment.
Energy-dependent dipole form factor in a QCD-inspired model
Bahia, C. A. S.; Broilo, M.; Luna, E. G. S.
2016-04-01
We consider the effect of an energy-dependent dipole form factor in the high-energy behavior of the forward amplitude. The connection between the semihard parton-level dynamics and the hadron-hadron scattering is established by an eikonal QCD-based model. Our results for the proton-proton (pp) and antiproton-proton (¯pp) total cross sections, σpp,\\bar{pp}tot(s), obtained using the CTEQ6L1 parton distribution function, are consistent with the recent data from the TOTEM experiment.
The noncommutative effects on the dipole moments of fermions in the standard model
Iltan, E.
2003-01-01
We study the dipole moments, electric dipole moment, weak electric dipole moment, anomalous magnetic moment, anomalous weak magnetic moment, of fermions in the noncommutative extension of the SM. We observe that the noncommutative effects are among the possible candidates to explain the electric and weak electric dipole moment of fermions. Furthermore, the upper bounds for the parameters which carry space-time and space-space noncommutativity can be obtained by using the theoretical and exper...
Quench Performance and Field Quality of FNAL Twin-Aperture 11 T Nb3Sn Dipole Model for LHC Upgrades
Stoynev, S; Apollinari, G; Auchmann, B; Barzi, E; Izquierdo Bermudez, S; Bossert, R; Chlachidze, G; DiMarco, J; Karppinen, M; Nobrega, F; Novitski, I; Rossi, F; Savary, F; Smekens, D; Strauss, T; Turrioni, D; Velev, G; Zlobin, A V
2016-01-01
A 2 m long single-aperture dipole demonstrator and two 1 m long single-aperture models based on Nb3Sn superconductor have been built and tested at FNAL. The two 1 m long collared coils were then assembled in a twin-aperture Nb3Sn dipole demonstrator compatible with the LHC main dipole and tested in two thermal cycles. This paper summarizes the quench performance of the FNAL twin-aperture Nb3Sn 11 T dipole in the temperature range of 1.9-4.5 K. The results of magnetic measurements for one of the two apertures are also presented. Test results are compared to the performance of coils in a single-aperture configuration. A summary of quench propagation studies in both apertures is given.
Energy Technology Data Exchange (ETDEWEB)
Nijhuis, A; Ilyin, Y; Abbas, W [Faculty of Science and Technology, Low Temperature Division, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands)], E-mail: a.nijhuis@tnw.utwente.nl
2008-06-15
We have measured the critical current (I{sub c}) of a high current density Nb{sub 3}Sn strand subjected to spatial periodic bending, periodic contact stress and uniaxial strain. The strand is destined for the cable-in-conduit conductors (CICC) of the European dipole (EDIPO) 12.5 T superconducting magnet test facility. The spatial periodic bending was applied on the strand, using the bending wavelengths from 5 to 10 mm with a peak bending strain of 1.5%, a periodic contact stress with a periodicity of 4.7 mm and a stress level exceeding 250 MPa. For the uniaxial strain characterization, the voltage-current characteristics were measured with an applied axial strain from -0.9% to +0.3%, with a magnetic field from 6 to 14 T, temperature from 4.2 to 10 K and currents up to almost 900 A. In addition the axial stiffness was determined by a tensile axial stress-strain test. The characterization of the strand is essential for understanding the behaviour of the strand under mainly axial thermal stress variation during cool down and transverse electromagnetic forces during charging, which is essential for the design of the CICC for the dipole magnet. The strand appears to be fully reversible in the compressive regime during the axial strain testing, while in the tensile regime, the behaviour is already irreversibly degraded when reaching the maximum in the critical current versus strain characteristic. The degradation is accentuated by an immediate decrease of the n value by a factor of 2. The parameters for the improved deviatoric strain description are derived from the I{sub c} data, giving the accuracy of the scaling with a standard deviation of 4 A, which is by far within the expected deviation for the large scale strand production of such a high J{sub c} strand. The I{sub c} versus the applied bending strain follows the low resistivity limit, indicative of full interfilament current transfer, while a strong decrease is observed at a peak bending strain of {approx}0
Considerations on a Cost Model for High-Field Dipole Arc Magnets for FCC
AUTHOR|(CDS)2078700; Durante, Maria; Lorin, Clement; Martinez, Teresa; Ruuskanen, Janne; Salmi, Tiina; Sorbi, Massimo; Tommasini, Davide; Toral, Fernando
2017-01-01
In the frame of the European Circular Collider (EuroCirCol), a conceptual design study for a post-Large Hadron Collider (LHC) research infrastructure based on an energy-frontier 100 TeV circular hadron collider [1]–[3], a cost model for the high-field dipole arc magnets is being developed. The aim of the cost model in the initial design phase is to provide the basis for sound strategic decisions towards cost effective designs, in particular: (A) the technological choice of superconducting material and its cost, (B) the target performance of Nb3Sn superconductor, (C) the choice of operating temperature (D) the relevant design margins and their importance for cost, (E) the nature and extent of grading, and (F) the aperture’s influence on cost. Within the EuroCirCol study three design options for the high field dipole arc magnets are under study: cos − θ [4], block [5], and common-coil [6]. Here, in the advanced design phase, a cost model helps to (1) identify the cost drivers and feed-back this informati...
Antila, Hanne S; Salonen, Emppu
2015-04-15
The Thole induced point dipole model is combined with three different point charge fitting methods, Merz-Kollman (MK), charges from electrostatic potentials using a grid (CHELPG), and restrained electrostatic potential (RESP), and two multipole algorithms, distributed multipole analysis (DMA) and Gaussian multipole model (GMM), which can be used to describe the electrostatic potential (ESP) around molecules in molecular mechanics force fields. This is done to study how the different methods perform when intramolecular polarizability contributions are self-consistently removed from the fitting done in the force field parametrization. It is demonstrated that the polarizable versions of the partial charge models provide a good compromise between accuracy and computational efficiency in describing the ESP of small organic molecules undergoing conformational changes. For the point charge models, the inclusion of polarizability reduced the the average root mean square error of ESP over the test set by 4-10%.
Milani, Alberto; Del Zoppo, Mirella; Tommasini, Matteo; Zerbi, Giuseppe
2008-02-14
In this work, we analyze the effect of intermolecular dipole-dipole interactions on Raman spectra of polyconjugated molecules. In particular, the behavior of push-pull polyenes has been studied. By means of density functional theory (DFT) calculations on isolated molecules and dimers, we have found that both the frequencies and intensities of the strongest Raman lines (R mode) are strongly influenced by intermolecular interactions. The results have been rationalized within the effective conjugation coordinate (ECC) theory developed in the past. The calculations for different configurations have also shown that the Raman spectra are sensible to different intermolecular geometries, thus implying a possible application of vibrational spectroscopy to the study of supramolecular properties of polyconjugated systems. The comparison with the available experimental spectra confirms the results obtained with the DFT computations. Finally, a very simple mathematical model is proposed for the prediction of the Raman frequencies of interacting systems. From the knowledge of just a few quantities for the isolated molecule and of some geometrical parameters, an estimate of the frequency of the dimers can be obtained. Despite its simplicity, this model gives results in very good agreement with DFT calculations carried out explicitly on dimers in several different arrangements.
Dipole Analysis of 249 High-Z SCP Union Supernovae According to the Expansion Center Model
Lorenzi, Luciano
2011-01-01
The topic of the paper is a preliminary analysis of 1743 data calculated for 249 High-z SCP Union supernovae, according to the expansion center model. The analysis of the ECM data set in Hubble units begins with 13 listed normal points corresponding to 13 z-bin samples at as many Hubble depths. Here the novel finding is a resulting clear drop in the average scattering of the SNe Ia absolute magnitudes M with the ECM Hubble depth D, after using the average trend computed in paper IX and here reconfirmed. Other correlations of the M scattering with the position in the sky are proposed as pointers for future investigations. Consequently, 13 ECM dipole tests on the 13 z-bin samples were carried out both with unweighed and weighed fittings. A further check was made through another ECM dipole test on the same 13 z bins, with Hubble depths D obtained by assuming M= according to paper IX and X. In conclusion the analysis of 249 SCP SNe confirms once again the expansion center model at any Hubble depth, including a s...
Extending the radial diffusion model of Falthammar to non-dipole background field
Energy Technology Data Exchange (ETDEWEB)
Cunningham, Gregory Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-05-26
A model for radial diffusion caused by electromagnetic disturbances was published by Falthammar (1965) using a two-parameter model of the disturbance perturbing a background dipole magnetic field. Schulz and Lanzerotti (1974) extended this model by recognizing the two parameter perturbation as the leading (non--dipole) terms of the Mead Williams magnetic field model. They emphasized that the magnetic perturbation in such a model induces an electric ield that can be calculated from the motion of field lines on which the particles are ‘frozen’. Roederer and Zhang (2014) describe how the field lines on which the particles are frozen can be calculated by tracing the unperturbed field lines from the minimum-B location to the ionospheric footpoint, and then tracing the perturbed field (which shares the same ionospheric footpoint due to the frozen -in condition) from the ionospheric footpoint back to a perturbed minimum B location. The instantaneous change n Roederer L*, dL*/dt, can then be computed as the product (dL*/dphi)*(dphi/dt). dL*/Dphi is linearly dependent on the perturbation parameters (to first order) and is obtained by computing the drift across L*-labeled perturbed field lines, while dphi/dt is related to the bounce-averaged gradient-curvature drift velocity. The advantage of assuming a dipole background magnetic field, as in these previous studies, is that the instantaneous dL*/dt can be computed analytically (with some approximations), as can the DLL that results from integrating dL*/dt over time and computing the expected value of (dL*)^2. The approach can also be applied to complex background magnetic field models like T89 or TS04, on top of which the small perturbations are added, but an analytical solution is not possible and so a numerical solution must be implemented. In this talk, I discuss our progress in implementing a numerical solution to the calculation of DL*L* using arbitrary background field models with simple electromagnetic
Cardiac magnetic source imaging based on current multipole model
Institute of Scientific and Technical Information of China (English)
Tang Fa-Kuan; Wang Qian; Hua Ning; Lu Hong; Tang Xue-Zheng; Ma Ping
2011-01-01
It is widely accepted that the heart current source can be reduced into a current multipole. By adopting three linear inverse methods, the cardiac magnetic imaging is achieved in this article based on the current multipole model expanded to the first order terms. This magnetic imaging is realized in a reconstruction plane in the centre of human heart, where the current dipole array is employed to represent realistic cardiac current distribution. The current multipole as testing source generates magnetic fields in the measuring plane, serving as inputs of cardiac magnetic inverse problem. In the heart-torso model constructed by boundary element method, the current multipole magnetic field distribution is compared with that in the homogeneous infinite space, and also with the single current dipole magnetic field distribution.Then the minimum-norm least-squares (MNLS) method, the optimal weighted pseuDOInverse method (OWPIM), and the optimal constrained linear inverse method (OCLIM) are selected as the algorithms for inverse computation based on current multipole model innovatively, and the imaging effects of these three inverse methods are compared. Besides,two reconstructing parameters, residual and mean residual, are also discussed, and their trends under MNLS, OWPIM and OCLIM each as a function of SNR are obtained and compared.
Pygmy and Giant Dipole Resonances by Coulomb Excitation using a Quantum Molecular Dynamics model
Tao, C; Zhang, G Q; Cao, X G; Wang, D Q Fang H W
2012-01-01
Pygmy and Giant Dipole Resonance (PDR and GDR) in Ni isotopes have been investigated by Coulomb excitation in the framework of the Isospin-dependent Quantum Molecular Dynamics model (IQMD). The spectra of $\\gamma$ rays are calculated and the peak energy, the strength and Full Width at Half Maximum (FWHM) of GDR and PDR have been extracted. Their sensitivities to nuclear equation of state, especially to its symmetry energy term are also explored. By a comparison with the other mean-field calculations, we obtain the reasonable values for symmetry energy and its slope parameter at saturation, which gives an important constrain for IQMD model. In addition, we also studied the neutron excess dependence of GDR and PDR parameters for Ni isotopes and found that the energy-weighted sum rule (EWSR) $PDR_{m_1}/GDR_{m_1}%$ increases linearly with the neutron excess.
Hard diffraction at HERA in the dipole model of BFKL dynamics
Munier, S; Royon, C; Royon, Ch.
1998-01-01
Using the QCD dipole picture of the hard BFKL pomeron, we derive the general expressions of the elastic and inelastic components of the proton diffractive structure functions. We obtain a good 7 parameter fit (including a secondary reggeon contribution) to data taken at HERA by the H1 and ZEUS collaborations. The main characteristic features of the model in reproducing the data are discussed, namely the effective pomeron intercept, the scaling violations and the beta dependence. A difference obtained in the separate H1 and ZEUS fits leads us to analyse directly the differences between both measurements. Predictions on R, the ratio of longitudinal to transverse photon cross sections are performed and lead to very large values at high beta and large virtuality Q which may lead to a discrimination between models.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
MEMS swallowable capsule is a novel technology in the non-invasive surgery. This technology provides a way to diagnose directly into the deep intestinal where the traditional invasive technology implemented, such as X-Ray, endoscopy. It is a key for us to locate and track the position of a MEMS capsule in clinical applications. To solve this problem, we implemented a magnetic sensor module based on the scalar form of the magnetic dipole model,which was designed with very small size (5.2 * 2.1 * 1.2 cm) and easy to assemble to satisfy the system requirement. Here we discuss in detail the principle of magnetic dipole model, rules of selecting sensor and functions of the module. Some trials are established to test the characteristic of the module. The results of the Cm experiment demonstrates that the module follows the rules of the new magnetic dipole model form.
Dipole model analysis of highest precision HERA data, including very low Q{sup 2}'s
Energy Technology Data Exchange (ETDEWEB)
Luszczak, A. [Cracow Univ. of Technology (Poland); Kowalski, H. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2016-12-15
We analyse, within a dipole model, the final, inclusive HERA DIS cross section data in the low χ region, using fully correlated errors. We show, that these highest precision data are very well described within the dipole model framework starting from Q{sup 2} values of 3.5 GeV{sup 2} to the highest values of Q{sup 2}=250 GeV{sup 2}. To analyze the saturation effects we evaluated the data including also the very low 0.35
Birotor dipole model for Saturn's inner magnetic field from CASSINI RPWS measurements and MAG data
Galopeau, Patrick H. M.
2016-10-01
The radio and plasma wave science (RPWS) experiment on board the Cassini spacecraft, orbiting around Saturn since July 2004, revealed the presence of two distinct and variable rotation periods in the Saturnian kilometric radiation (SKR). These two periods were attributed to the northern and southern hemispheres respectively. The existence of a double period makes the study of the planetary magnetic field much more complicated and the building of a field model, based on the direct measurements of the MAG experiment from the magnetometers embarked on board Cassini, turns out to be uncertain. The first reason is the difficulty for defining a longitude system linked to the variable period, because the internal magnetic field measurements from MAG are not continuous. The second reason is the existence itself of two distinct periods which could imply the existence of a double rotation magnetic structure generated by Saturn's dynamo. However, the radio observations from the RPWS experiment allow a continuous and accurate follow-up of the rotation phase of the variable two periods, since the SKR emission is permanently observable and produced very close to the planetary surface. A wavelet transform analysis of the intensity of the SKR signal received at 290 kHz was performed in order to calculate the rotation phase of each Saturnian hemisphere. A dipole model was proposed for Saturn's inner magnetic field: this dipole presents the particularity to rotate around Saturn's axis at two different angular velocities; it is tilted and not centered. Then it is possible to fit the MAG data for each Cassini's revolution around the planet the periapsis of which is less than 5 Saturnian radii. This study suggests that Saturn's inner magnetic field is neither stationary nor fully axisymmetric. Such a result can be used as a boundary condition for modelling and constraining the planetary dynamo.
Magnetic dipole moment of a moving electric dipole
Hnizdo, V.
2012-01-01
The current density of a moving electric dipole is expressed as the sum of polarization and magnetization currents. The magnetic field due to the latter current is that of a magnetic dipole moment that is consistent with the relativistic transformations of the polarization and magnetization of macroscopic electrodynamics.
RCS estimation of linear and planar dipole phased arrays approximate model
Singh, Hema; Jha, Rakesh Mohan
2016-01-01
In this book, the RCS of a parallel-fed linear and planar dipole array is derived using an approximate method. The signal propagation within the phased array system determines the radar cross section (RCS) of phased array. The reflection and transmission coefficients for a signal at different levels of the phased-in scattering array system depend on the impedance mismatch and the design parameters. Moreover the mutual coupling effect in between the antenna elements is an important factor. A phased array system comprises of radiating elements followed by phase shifters, couplers, and terminating load impedance. These components lead to respective impedances towards the incoming signal that travels through them before reaching receive port of the array system. In this book, the RCS is approximated in terms of array factor, neglecting the phase terms. The mutual coupling effect is taken into account. The dependence of the RCS pattern on the design parameters is analyzed. The approximate model is established as a...
Conductivity analysis of epoxy/carbon nanotubes composites by dipole relaxation and hopping models
Ramos, Airton; Pezzin, Sergio H.; Farias, Heric Denis; Becker, Daniela; Bello, Roger H.; Coelho, Luiz A. F.
2016-10-01
In this study it was used a numerical technique of successive approximations to estimate parameters of a conductivity model that includes the hopping process and the dipole relaxation for the purpose of describing the behavior of the conductivity measured on nanocomposites with carbon nanotubes in epoxy resin in the range of frequency of 100 Hz to 40 MHz. Two relaxation bands were detected, one with a response below 10 kHz and one above 10 MHz. For the first band, it was observed that the nanocomposites become more conductive, and its conductivity less temperature dependent, as the nanotube content increases. The second band is characterized by a large spread in relaxation time. The results show that the percolation threshold is below 0.15 vol% and that 'ac' hopping is the main transport process above 100 kHz, becoming dominant with respect to percolation at higher temperatures (>340 K).
The variation of the fine structure constant: testing the dipole model with thermonuclear supernovae
Kraiselburd, Lucila; Negrelli, Carolina; Berro, Enrique García
2014-01-01
The large-number hypothesis conjectures that fundamental constants may vary. Accordingly, the spacetime variation of fundamental constants has been an active subject of research for decades. Recently, using data obtained with large telescopes a phenomenological model in which the fine structure constant might vary spatially has been proposed. We test whether this hypothetical spatial variation of {\\alpha}, which follows a dipole law, is compatible with the data of distant thermonuclear supernovae. Unlike previous works, in our calculations we consider not only the variation of the luminosity distance when a varying {\\alpha} is adopted, but we also take into account the variation of the peak luminosity of Type Ia supernovae resulting from a variation of {\\alpha}. This is done using an empirical relation for the peak bolometric magnitude of thermonuclear supernovae that correctly reproduces the results of detailed numerical simulations. We find that there is no significant difference between the several phenome...
Electric dipole moment induced by CP-violating deformations in the noncommutative Standard Model
Wang, Wei-Jian; Yan, Zhe-Hui; Guan, Rong-Hua; Wei, Xing-Ning
2017-03-01
The possibility to detect the noncommutative (NC) spacetime in the electric dipole moments (EDM) experiments is studied in the effective field theory of noncommutative Standard Model (NCSM) with many additional deformations. The EDM given by the previous literatures do not have any observable effect since they are spin-independent. In this work, it is found that three of the deformed terms provide extra sources of CP violation contributed to EDM. We show that these EDMs are sensitive to the spin and thus have potential to be measured in the highly precise experiments. In particular, the EDM induced by NC spacetime may not be parallel to the direction of spin, which demonstrates the intrinsic feature of NC field theory.
Limits on the electromagnetic and weak dipole moments of the tau-lepton in a 331 model
Energy Technology Data Exchange (ETDEWEB)
Gutiérrez-Rodríguez, A. [Facultad de Física, Universidad Autónoma de Zacatecas Apartado, Postal C-580, 98060 Zacatecas, México (Mexico); Hernández-Ruíz, M.A. [Facultad de Ciencias Químicas, Universidad Autónoma de Zacatecas Apartado, Postal 585, 98060 Zacatecas, México (Mexico); Castañeda-Almanza, C.P.; Espinoza-Garrido, A.; Chubykalo, A. [Facultad de Física, Universidad Autónoma de Zacatecas Apartado, Postal C-580, 98060 Zacatecas, México (Mexico)
2014-08-15
Using as an input the data obtained by the L3 and OPAL Collaborations for the reaction e{sup +}e{sup −}→τ{sup +}τ{sup −}γ at the Z{sub 1}-pole, we obtained bounds on the electromagnetic and weak dipole moments of the tau-lepton in the context of a 331 model. Our bounds on the electromagnetic moments are consistent with the bounds obtained by the L3 and OPAL Collaborations for the reaction e{sup +}e{sup −}→τ{sup +}τ{sup −}γ. We also obtained bounds on the tau weak dipole moments which are consistent with the bounds obtained recently by the DELPHI, ALEPH and BELLE Collaborations from the reaction e{sup +}e{sup −}→τ{sup +}τ{sup −}. Our work complements other studies on the electromagnetic and weak dipole moments of the tau-lepton.
Bentz, Erika N; Pomilio, Alicia B; Lobayan, Rosana M
2014-12-01
The extension of the study of the conformational space of the structure of (+)-catechin at the B3LYP/6-31G(d,p) level of theory is presented in this paper. (+)-Catechin belongs to the family of the flavan-3-ols, which is one of the five largest phenolic groups widely distributed in nature, and whose biological activity and pharmaceutical utility are related to the antioxidant activity due to their ability to scavenge free radicals. The effects of free rotation around all C-O bonds of the OH substituents at different rings are taken into account, obtaining as the most stable conformer, one that had not been previously reported. One hundred seven structures, and a study of the effects of charge delocalization and stereoelectronic effects at the B3LYP/6-311++G(d,p) level are reported by natural bond orbital analysis, streamlining the order of these structures. For further analysis of the structural and molecular properties of this compound in a biological environment, the calculation of polarizabilities, and the study of the electric dipole moment are performed considering the whole conformational space described. The results are analyzed in terms of accumulated knowledge for (4α → 6″, 2α → O → 1″)-phenylflavans and (+)-catechin in previous works, enriching the study of both types of structures, and taking into account the importance of considering the whole conformational space in modeling both the polarizability and the electric dipole moment, also proposing to define a descriptive subspace of only 16 conformers.
Johnson, Mikala; Bowen, Patrick; Kundtz, Nathan; Bily, Adam
2014-09-01
Since the discovery of materials with negative refractive index, widely known as metamaterials, it has been possible to develop new devices that utilize a metamaterial's ability to control the path of electromagnetic energy. Of particular promise, and already under intensive development for commercial applications, are metamaterial antennas for satellite communications. Using reconfigurable metamaterials in conjunction with the principles of holography, these new antennas can electronically steer the high gain antenna beam required for broadband communications while not having any moving parts, being thinner, lighter weight, and less expensive, and requiring less power to operate than conventional alternatives. Yet, the promise of these devices will not be realized without efficient and effective control and optimization. Toward this end, in this paper a discrete-dipole approximation (DDA) model of a waveguide-fed planar metamaterial antenna is derived. The proposed model is demonstrated to accurately predict the radiation of a two-dimensional metamaterial at a much reduced computational cost to full-wave simulation and at much greater fidelity than simpler models typically used in the field. The predictive capabilities of the derived DDA model opens possibilities for model-based control design for optimal beam steering.
Energy Technology Data Exchange (ETDEWEB)
Manteuffel, Andreas von
2008-07-17
Theories with extended Higgs sectors such as Two-Higgs-Doublet Models (THDMs) or the Next-to-Minimal Supersymmetric Standard Model (NMSSM) allow for rich CP phenomena and involved Higgs-potential structures. Employing a gauge invariant formulation for the tree-level Higgs potential of the general THDM, we derive compact criteria for its stability, electroweak symmetry breaking, and generalised CP properties in a clear geometrical language. A new type of CP symmetry is shown to impose strong restrictions on the Lagrangian and to require at least two fermion generations for non-trivial Yukawa terms. Large regions of the NMSSM parameter space are excluded due to an instable vacuum. We present a rigorous determination of the global minimum of the tree-level potential via Groebner bases. In a second part, we investigate the colour dipole picture. This model of high energy photonproton scattering permits a very successful description of available HERA data. Nevertheless, its range of applicability is limited. We derive general bounds on ratios of deep-inelastic proton structure functions within the colour dipole picture, following exclusively from its framework and photon wave function properties. Confronting these bounds with HERA data we can further restrict the range of applicability of the colour dipole picture. Finally, we calculate Ioffe times for a specific model and find them to be too small to justify the dipole picture at large photon virtualities. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Miyamoto, R.; Kopp, S.E.; /Texas U.; Jansson, A.; Syphers, M.J.; /Fermilab
2007-06-01
The AC dipole is an oscillating dipole magnet which can induce large amplitude oscillations without the emittance growth and decoherence. These properties make it a good tool to measure optics of a hadron synchrotron. The vertical AC dipole for the Tevatron is powered by an inexpensive high power audio amplifier since its operating frequency is approximately 20 kHz. The magnet is incorporated into a parallel resonant system to maximize the current. The use of a vertical pinger magnet which has been installed in the Tevatron made the cost relatively inexpensive. Recently, the initial system was upgraded with a more powerful amplifier and oscillation amplitudes up to 2-3{sigma} were achieved with the 980 GeV proton beam. This paper discusses details of the Tevatron AC dipole system and also shows its test results.
A continuum model for current distribution in Rutherford cables
Akhmedov, A I; Breschi, M
2001-01-01
An analysis of eddy currents induced in flat Rutherford-type cables by external time dependent magnetic fields has been performed. The induced currents generate in turn a secondary magnetic field which has a longitudinal periodicity (periodic pattern). The dependence of the amplitude of the pattern on the history of the cable excitation has been investigated. The study has been carried out with two different models for the simulation of current distribution in Rutherford cables, namely a network model, based on a lumped parameters circuit and a "continuum" model, based on a distributed parameters circuit. We show the results of simulations of the current distribution in the inner cable of a short LHC dipole model in different powering conditions and compare them to experimental data. (12 refs).
Energy Technology Data Exchange (ETDEWEB)
Walder, Brennan J.; Davis, Michael C.; Grandinetti, Philip J. [Department of Chemistry, Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210 (United States); Dey, Krishna K. [Department of Physics, Dr. H. S. Gour University, Sagar, Madhya Pradesh 470003 (India); Baltisberger, Jay H. [Division of Natural Science, Mathematics, and Nursing, Berea College, Berea, Kentucky 40403 (United States)
2015-01-07
A new two-dimensional Nuclear Magnetic Resonance (NMR) experiment to separate and correlate the first-order quadrupolar and chemical/paramagnetic shift interactions is described. This experiment, which we call the shifting-d echo experiment, allows a more precise determination of tensor principal components values and their relative orientation. It is designed using the recently introduced symmetry pathway concept. A comparison of the shifting-d experiment with earlier proposed methods is presented and experimentally illustrated in the case of {sup 2}H (I = 1) paramagnetic shift and quadrupolar tensors of CuCl{sub 2}⋅2D{sub 2}O. The benefits of the shifting-d echo experiment over other methods are a factor of two improvement in sensitivity and the suppression of major artifacts. From the 2D lineshape analysis of the shifting-d spectrum, the {sup 2}H quadrupolar coupling parameters are 〈C{sub q}〉 = 118.1 kHz and 〈η{sub q}〉 = 0.88, and the {sup 2}H paramagnetic shift tensor anisotropy parameters are 〈ζ{sub P}〉 = − 152.5 ppm and 〈η{sub P}〉 = 0.91. The orientation of the quadrupolar coupling principal axis system (PAS) relative to the paramagnetic shift anisotropy principal axis system is given by (α,β,γ)=((π)/2 ,(π)/2 ,0). Using a simple ligand hopping model, the tensor parameters in the absence of exchange are estimated. On the basis of this analysis, the instantaneous principal components and orientation of the quadrupolar coupling are found to be in excellent agreement with previous measurements. A new point dipole model for predicting the paramagnetic shift tensor is proposed yielding significantly better agreement than previously used models. In the new model, the dipoles are displaced from nuclei at positions associated with high electron density in the singly occupied molecular orbital predicted from ligand field theory.
Finite dipole model for extreme near-field thermal radiation between a tip and planar SiC substrate
Jarzembski, Amun; Park, Keunhan
2017-04-01
Recent experimental studies have measured the infrared (IR) spectrum of tip-scattered near-field thermal radiation for a SiC substrate and observed up to a 50cm-1 redshift of the surface phonon polariton (SPhP) resonance peak [1,2]. However, the observed spectral redshift cannot be explained by the conventional near-field thermal radiation model based on the point dipole approximation. In the present work, a heated tip is modeled as randomly fluctuating point charges (or fluctuating finite dipoles) aligned along the primary axis of a prolate spheroid, and quasistatic tip-substrate charge interactions are considered to formulate the effective polarizability and self-interaction Green's function. The finite dipole model (FDM), combined with fluctuational electrodynamics, allows the computation of tip-plane thermal radiation in the extreme near-field (i.e., H / R ≲ 1 , where H is the tip-substrate gap distance and R is the tip radius), which cannot be calculated with the point dipole approximation. The FDM provides the underlying physics on the spectral redshift of tip-scattered near-field thermal radiation as observed in experiments. In addition, the SPhP peak in the near-field thermal radiation spectrum may split into two peaks as the gap distance decreases into the extreme near-field regime. This observation suggests that scattering-type spectroscopic measurements may not convey the full spectral features of tip-plane extreme near-field thermal radiation.
Pygmy dipole resonance and dipole polarizability in 90Zr
Iwamoto, C.; Tamii, A.; Utsunomiya, H.; Akimune, H.; Nakada, H.; Shima, T.; Hashimoto, T.; Yamagata, T.; Kawabata, T.; Fujita, Y.; Matsubara, H.; Suzuki, T.; Fujita, H.; Shimbara, Y.; Nagashima, M.; Sakuda, M.; Mori, T.; Izumi, T.; Okamoto, A.; Kondo, T.; Lui, T.-W.; Bilgier, B.; Kozer, H. C.; Hatanaka, K.
2014-05-01
Electric dipole (E1) reduced transition probability B(E1) of 90Zr was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the E1 strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability αD which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.
Pygmy dipole resonance and dipole polarizability in {sup 90}Zr
Energy Technology Data Exchange (ETDEWEB)
Iwamoto, C.; Tamii, A.; Shima, T.; Hashimoto, T.; Suzuki, T.; Fujita, H.; Hatanaka, K. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Utsunomiya, H.; Akimune, H.; Yamagata, T.; Okamoto, A.; Kondo, T. [Department of Physics, Konan University, Okamoto 8-9-1, Higashinada, Kobe 658-8501 (Japan); Nakada, H. [Department of Physics, Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage, Chiba 263-8522 (Japan); Kawabata, T. [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Fujita, Y. [Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 (Japan); Matsubara, H. [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan); Shimbara, Y.; Nagashima, M. [Department of Physics, Niigata University, Niigata 950-21-2 (Japan); Sakuda, M.; Mori, T. [Department of Physics, Okayama University, Okayama 900-0082 (Japan); and others
2014-05-02
Electric dipole (E1) reduced transition probability B(E1) of {sup 90}Zr was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the E1 strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability α{sub D} which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.
Quantum emitter dipole-dipole interactions in nanoplasmonic systems
Nečada, Marek; Törmä, Päivi
2016-01-01
We introduce a generalized Dicke-like model to describe two-level systems coupled with a single bosonic mode. In addition, the two-level systems mutually interact via direct dipole-dipole interaction. We apply the model to an ensemble of dye molecules coupled to a plasmonic excitation in a metallic nanoparticle and study how the dipole-dipole interaction and configurational randomness introduced to the system affect the energy spectra. Comparing the system eigenenergies obtained by our model with the light spectra from a multiple-scattering simulation, we suggest a way to identify dark modes in our model. Finally, we perform a parameter sweep in order to determine the scaling properties of the system and to classify the regions of the parameter space where the dipole-dipole interactions can have significant effects.
Energy Technology Data Exchange (ETDEWEB)
Hohmann, G.W.; Jiracek, G.R.
1979-09-01
The bipole-dipole responses of three-dimensional (3D) prisms were studied using an integral equation numerical solution. Although response patterns are quite complex, the bipole-dipole method appears to be a useful, efficient means of mapping the areal distribution of resistivity. However, 3D modeling is required for quantitative interpretation. Computer time for our solution varies from negligible for small bodies to 6 minutes on a UNIVAC 1108 for the largest possible body (85 cubes). Bipole-dipole response varies significantly with bipole orientation and position, but simply changing the distance between the bipole and the body does not greatly affect the response. However, the response is complex and interpretation ambiguous if both transmitter electrodes are located directly over a body. Boundaries of shallow bodies are much better resolved than those of deep bodies. Conductive bodies produce false polarization highs that can confuse interpretation. It is difficult to distinguish the effects of depth and resistivity contrast, and, as with all electrical methods, depth extent is difficult to resolve. Interactive interpretation of bipole-dipole field results from a geothermal prospect in New Mexico illustrates the value of the 3D modeling technique.
Thermal shape fluctuation model study of the giant dipole resonance in $^{152}$Gd
Kumar, A K Rhine
2015-01-01
We have studied the giant dipole resonance (GDR) in the hot and rotating nucleus $^{152}$Gd within the framework of thermal shape fluctuation model (TSFM) built on the microscopic-macroscopic calculations of the free energies with a macroscopic approach for the GDR. Our results for GDR cross sections are in good agreement with the experimental values except for a component peaking around 17 MeV where the data has large uncertainties. Such a component is beyond our description which properly takes care of the splitting of GDR components due to the deformation and Coriolis effects. Around this 17 MeV lies the half maximum in experimental cross sections, and hence the extracted GDR widths and deformations (estimated from these widths) turn out to be overestimated and less reliable. Reproducing these widths with empirical formulae could conceal the information contained in the cross sections. Fully microscopic GDR calculations and a more careful look at the data could be useful to understand the GDR component aro...
Equilibrium points in the restricted synchronous three-body problem using a mass dipole model
Barbosa Torres dos Santos, Leonardo; Bertachini de Almeida Prado, Antonio F.; Merguizo Sanchez, Diogo
2017-03-01
The objective of the present paper is to investigate the zero velocity curves, using the Jacobi constant C, and to determine the positions of the libration points in the restricted synchronous three-body problem. To perform this task, it is necessary to obtain the equations of motion of a negligible mass traveling in a system composed of two other massive bodies. One of them is assumed to have a spherical shape, while the other one is irregular shaped and modeled as a rotating mass dipole. The locations of the equilibrium points are determined and then, for several values C of the Jacobi constant, the boundary regions are obtained where the motion of the particle is allowed. The zero velocity curves are plotted. Next, the stability of these equilibrium points examined, including the collinear and non-collinear ones. It is found that the collinear points are unstable and the non-collinear ones are linearly stable for lower values of the mass parameter. A comparison with the equivalent results for the dynamics considering three points of mass is made, to emphasize the influence of the elongation of one of the bodies.
Whittleton, Sarah R; Otero-de-la-Roza, A; Johnson, Erin R
2017-02-14
Accurate energy ranking is a key facet to the problem of first-principles crystal-structure prediction (CSP) of molecular crystals. This work presents a systematic assessment of B86bPBE-XDM, a semilocal density functional combined with the exchange-hole dipole moment (XDM) dispersion model, for energy ranking using 14 compounds from the first five CSP blind tests. Specifically, the set of crystals studied comprises 11 rigid, planar compounds and 3 co-crystals. The experimental structure was correctly identified as the lowest in lattice energy for 12 of the 14 total crystals. One of the exceptions is 4-hydroxythiophene-2-carbonitrile, for which the experimental structure was correctly identified once a quasi-harmonic estimate of the vibrational free-energy contribution was included, evidencing the occasional importance of thermal corrections for accurate energy ranking. The other exception is an organic salt, where charge-transfer error (also called delocalization error) is expected to cause the base density functional to be unreliable. Provided the choice of base density functional is appropriate and an estimate of temperature effects is used, XDM-corrected density-functional theory is highly reliable for the energetic ranking of competing crystal structures.
Surface Adsorption from the Exchange-Hole Dipole Moment Dispersion Model.
Christian, Matthew S; Otero-de-la-Roza, Alberto; Johnson, Erin R
2016-07-12
The accurate calculation of intermolecular interaction energies with density functional theory requires methods that include a treatment of long-range, nonlocal dispersion correlation. In this work, we explore the ability of the exchange-hole dipole moment (XDM) dispersion correction to model molecular surface adsorption. Adsorption energies are calculated for six small aromatic molecules (benzene, furan, pyridine, thiophene, thiophenol, and benzenediamine) and the four DNA nucleobases (adenine, thymine, guanine, and cytosine) on the (111) surfaces of the three coinage metals (copper, silver, and gold). For benzene, where the experimental reference data is most precise, the mean absolute error in the computed absorption energies is 0.04 eV. For the other aromatic molecules, the computed binding energies are found to be within 0.09 eV of the available reference data, on average, which is well below the expected experimental uncertainties for temperature-programmed desorption measurements. Unlike other dispersion-corrected functionals, adequate performance does not require changes to the canonical XDM implementation, and the good performance of XDM is explained in terms of the behavior of the exchange hole. Additionally, the base functional employed (B86bPBE) is also optimal for molecular studies, making B86bPBE-XDM an excellent candidate for studying chemistry on material surfaces. Finally, the noncovalent interaction (NCI) plot technique is shown to detect adsorption effects in real space on the order of tenths of an eV.
Far-field Fano resonance in nanoring lattices modeled from extracted, point dipole polarizability
Energy Technology Data Exchange (ETDEWEB)
DeJarnette, Drew; Forcherio, Gregory T. [Microelectronics and Photonics Graduate Program, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Blake, Phillip [Department of Chemical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Keith Roper, D., E-mail: dkroper@uark.edu [Microelectronics and Photonics Graduate Program, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Department of Chemical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States)
2014-01-14
Coupling and extinction of light among particles representable as point dipoles can be characterized using the coupled dipole approximation (CDA). The analytic form for dipole polarizability of spheroidal particles supports rapid electrodynamic analysis of nanoparticle lattices using CDA. However, computational expense increases for complex shapes with non-analytical polarizabilities which require discrete dipole (DDA) or higher order approximations. This work shows fast CDA analysis of assembled nanorings is possible using a single dipole nanoring polarizability extrapolated from a DDA calculation by summing contributions from individual polarizable volume elements. Plasmon resonance wavelengths of nanorings obtained using extracted polarizabilities blueshift as wall dimensions-to-inner radius aspect ratio increases, consistent with published theory and experiment. Calculated far-field Fano resonance energy maximum and minimum wavelengths were within 1% of full volume element results. Considering polarizability allows a more complete physical picture of predicting plasmon resonance location than metal dielectric alone. This method reduces time required for calculation of diffractive coupling more than 40 000-fold in ordered nanoring systems for 400–1400 nm incident wavelengths. Extension of this technique beyond nanorings is possible for more complex shapes that exhibit dipolar or quadrupole radiation patterns.
Quench Protection Studies of 11T Nb$_3$Sn Dipole Models for LHC Upgrades
Energy Technology Data Exchange (ETDEWEB)
Zlobin, Alexander [Fermilab; Chlachidze, Guram [Fermilab; Nobrega, Alfred [Fermilab; Novitski, Igor [Fermilab; Karppinen, Mikko [CERN
2014-07-01
CERN and FNAL are developing 11 T Nb3Sn dipole magnets for the LHC collimation system upgrade. Due to the large stored energy, protection of these magnets during a quench is a challenging problem. This paper reports the results of experimental studies of key quench protection parameters including longitudinal and radial quench propagation in the coil, coil heating due to a quench, and energy extraction and quench-back effect. The studies were performed using a 1 m long 11 T Nb3Sn dipole coil tested in a magnetic mirror configuration.
Localization technique research of a pipeline robot based on the magnetic-dipole model
Institute of Scientific and Technical Information of China (English)
Junyuan LI; Hongjun CHEN; Shengfeng LI; Xiaohua ZHANG
2008-01-01
The magnetic field distribution of an emission antenna is studied in this paper. When the slenderness ratio of the emission antenna is high, the emission antenna can be simplified as a magnetic dipole for practical application. The numerical results of the magnetic dipole magnetic field show that the magnetic magnitude dis-tribution has a hump-shape, whose direction is perpendi-cular with the antenna axis direction. A localization method based on the hump-shape signal detection is presented. The experimental result shows that the preci-sion can reach a value of + 5 cm. The method can be used to localize a pipeline robot working in a metal pipe.
Genetic algorithms for dipole location of fetal magnetocardiography.
Escalona-Vargas, D; Murphy, P; Lowery, C L; Eswaran, H
2016-08-01
In this paper, we explore the use of Maximum Likelihood (ML) method with Genetic Algorithms (GA) as global optimization procedure for source reconstruction in fetal magnetocardiography (fMCG) data. A multiple equivalent current dipole (ECD) model was used for sources active in different time samples. Inverse solutions across time were obtained for a single-dipole approximation to estimate the trajectory of the dipole position. We compared the GA and SIMPLEX methods in a simulation environment under noise conditions. Methods are applied on a real fMCG data. Results show robust estimators of the cardiac sources when GA is used as optimization technique.
Michálek, Tomáš; Zemánek, Jiří
2017-03-16
Mathematical models of dielectrophoresis play an important role in the design of experiments, analysis of results, and even operation of some devices. In this paper, we test the accuracy of existing models in both simulations and laboratory experiments. We test the accuracy of the most common model that involves a point-dipole approximation of the induced field, when the small-particle assumption is broken. In simulations, comparisons against a model based on the Maxwell stress tensor show that even the point-dipole approximation provides good results for a large particle close to the electrodes. In addition, we study a refinement of the model offered by multipole approximations (quadrupole, and octupole). We also show that the voltages on the electrodes influence the error of the model because they affect the positions of the field nulls and the nulls of the higher-order derivatives. Experiments with a parallel electrode array and a polystyrene microbead reveal that the models predict the force with an error that cannot be eliminated even with the most accurate model. Nonetheless, it is acceptable for some purposes such as a model-based control system design. This article is protected by copyright. All rights reserved.
Giorgi, Giacomo; Yamashita, Koichi
2015-11-06
Starting from a brief description of the main architectures characterizing the novel solar technology of perovskite-based solar cells, we focus our attention on the anomalous hysteresis experimentally found to affect the measurement of the current-voltage curve of such devices. This detrimental effect, associated with slow dynamic reorganization processes, depends on several parameters; among them, the scan rate of the measurements, the architecture of the cell, and the perovskite deposition rate are crucial. Even if a conclusive explanation of the origin of the hysteresis has not been provided so far, several experimental findings ascribe its origin to ionic migration at an applied bias and dielectric polarization that occurs in the perovskite layer. Consistently, a dipole-moment-reduced cation such as formamidinium ion is experimentally reported to quantitatively reduce the hysteresis from perovskite-based devices. By means of a density-functional theory-based set of calculations, we have predicted and characterized guanidinium ion (GA = (+)[C(NH2)3], a zero-dipole moment cation by symmetry)-based organic-inorganic halide perovskite's structural and electronic properties, speculating that such a cation and the alloys it may form with other organic cations can represent a possible chemical solution for the puzzling issue of the hysteresis.
Wilson, Jeffrey D.; Zimmerli, Gregory A.
2012-01-01
Good antenna-mode coupling is needed for determining the amount of propellant in a tank through the method of radio frequency mass gauging (RFMG). The antenna configuration and position in a tank are important factors in coupling the antenna to the natural electromagnetic modes. In this study, different monopole and dipole antenna mounting configurations and positions were modeled and responses simulated in a full-scale tank model with the transient solver of CST Microwave Studio (CST Computer Simulation Technology of America, Inc.). The study was undertaken to qualitatively understand the effect of antenna design and placement within a tank on the resulting radio frequency (RF) tank spectrum.
Liguori, Giovanni; Di Lorenzo, Emanuele; Cabos, William
2017-02-01
Changes in surface heat fluxes affect several climate processes controlling the Mediterranean climate. These include the winter formation of deep waters, which is the primary driver of the Mediterranean Sea overturning circulation. Previous studies that characterize the spatial and temporal variability of surface heat flux anomalies over the basin reveal the existence of two statistically dominant patterns of variability: a monopole of uniform sign and an east-west dipole of opposite signs. In this work, we use the 12 regional climate model ensemble from the EU-FP6 ENSEMBLES project to diagnose the large-scale atmospheric processes that control the variability of heat fluxes over the Mediterranean Sea from interannual to decadal timescales (here defined as timescales > 6 year). Our findings suggest that while the monopole structure captures variability in the winter-to-winter domain-average net heat flux, the dipole pattern tracks changes in the Mediterranean climate that are connected to the East Atlantic/Western Russia (EA/WR) atmospheric teleconnection pattern. Furthermore, while the monopole exhibits significant differences in the spatial structure across the multi-model ensemble, the dipole pattern is very robust and more clearly identifiable in the anomaly maps of individual years. A heat budget analysis of the dipole pattern reveals that changes in winds associated with the EA/WR pattern exert dominant control through both a direct effect on the latent heat flux (i.e., wind speed) and an indirect effect through specific humidity (e.g., wind advection). A simple reconstruction of the heat flux variability over the deep-water formation regions of the Gulf of Lion and the Aegean Sea reveals that the combination of the monopole and dipole time series explains over 90 % of the heat flux variance in these regions. Given the important role that surface heat flux anomalies play in deep-water formation and the regional climate, improving our knowledge on the dynamics
Liu, Lixia; Xie, Hong; Bostic, Heidi E; Jin, Limei; Best, Michael D; Zhang, X Peter; Zhan, Wei
2013-08-26
When a phospholipid monolayer containing a zinc-coordinated porphyrin species formed atop a self-assembled monolayer of heptadecafluoro-1-decanethiol (CF3(CF2)7(CH2)2SH) is subjected to photoelectrochemical current generation, a significant modulation effect is observed. Compared with devices that contain similar photoactive lipid monolayers but formed on 1-dodecanethiol SAMs, these fluorinated hybrid bilayers produce a >60% increase in cathodic currents and a similar decrease in anodic currents. Photovoltages recorded from these hybrid bilayers are found to vary in the same fashion. The modulation of photovoltaic responses in these hybrid-bilayer-based devices is explained by the opposite surface dipoles associated with the thiols employed in this study, which in one case (fluorothiol) increase and in another (alkanethiol) decrease the work function of the underlying gold substrates. A similar trend of photovoltage/photocurrent modulation is also observed if fullerene is used as the photoagent in these devices. Our results reveal the intricacy of orientated surface dipole in influencing the photovoltaic processes, and its subtle interplay with other factors related to the photoagents, such as their location and orientation within the organic matrix.
Liu, Lixia
2013-06-21
When a phospholipid monolayer containing a zinc-coordinated porphyrin species formed atop a self-assembled monolayer of heptadecafluoro-1-decanethiol (CF3(CF2)7(CH2)2SH) is subjected to photoelectrochemical current generation, a significant modulation effect is observed. Compared with devices that contain similar photoactive lipid monolayers but formed on 1-dodecanethiol SAMs, these fluorinated hybrid bilayers produce a >60 % increase in cathodic currents and a similar decrease in anodic currents. Photovoltages recorded from these hybrid bilayers are found to vary in the same fashion. The modulation of photovoltaic responses in these hybrid-bilayer-based devices is explained by the opposite surface dipoles associated with the thiols employed in this study, which in one case (fluorothiol) increase and in another (alkanethiol) decrease the work function of the underlying gold substrates. A similar trend of photovoltage/photocurrent modulation is also observed if fullerene is used as the photoagent in these devices. Our results reveal the intricacy of orientated surface dipole in influencing the photovoltaic processes, and its subtle interplay with other factors related to the photoagents, such as their location and orientation within the organic matrix. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Splitting of the Dipole and Spin Dipole Resonances in Pb
Austin, Sam M.
2000-10-01
The response to different neutrino flavors of a supernova neutrino detector based on Pb depends on the position of the spin-dipole resonance(Fuller, Fowler and McLaughlin, Phys. Rev. D59,085005(1999)). In this talk I will present a phenomenolgical model that allows one to extract the splitting of the dipole and spin-dipole resonances from the variation with bombarding energy of the L=1 resonance in (p,n) reactions. This model has been applied previously to the Zr isotopes (Sam M. Austin, Phys. Rev. C, submitted). The dipole splitting for ^208Pb is determined from available data on the (p,n) reaction for bombarding energies between 45 to 200 MeV. It is found to be 4.7±2.0 MeV, with the spin-dipole resonance lying at lower excitation energy.
Energy Technology Data Exchange (ETDEWEB)
Liu, Hanchao; Wang, Yimin; Bowman, Joel M. [Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322 (United States)
2015-05-21
The calculation and characterization of the IR spectrum of liquid water have remained a challenge for theory. In this paper, we address this challenge using a combination of ab initio approaches, namely, a quantum treatment of IR spectrum using the ab initio WHBB water potential energy surface and a refined ab initio dipole moment surface. The quantum treatment is based on the embedded local monomer method, in which the three intramolecular modes of each embedded H{sub 2}O monomer are fully coupled and also coupled singly to each of six intermolecular modes. The new dipole moment surface consists of a previous spectroscopically accurate 1-body dipole moment surface and a newly fitted ab initio intrinsic 2-body dipole moment. A detailed analysis of the new dipole moment surface in terms of the coordinate dependence of the effective atomic charges is done along with tests of it for the water dimer and prism hexamer double-harmonic spectra against direct ab initio calculations. The liquid configurations are taken from previous molecular dynamics calculations of Skinner and co-workers, using the TIP4P plus E3B rigid monomer water potential. The IR spectrum of water at 300 K in the range of 0–4000 cm{sup −1} is calculated and compared with experiment, using the ab initio WHBB potential and new ab initio dipole moment, the q-TIP4P/F potential, which has a fixed-charged description of the dipole moment, and the TTM3-F potential and dipole moment surfaces. The newly calculated ab initio spectrum is in very good agreement with experiment throughout the above spectral range, both in band positions and intensities. This contrasts to results with the other potentials and dipole moments, especially the fixed-charge q-TIP4P/F model, which gives unrealistic intensities. The calculated ab initio spectrum is analyzed by examining the contribution of various transitions to each band.
Liu, Hanchao; Wang, Yimin; Bowman, Joel M
2015-05-21
The calculation and characterization of the IR spectrum of liquid water have remained a challenge for theory. In this paper, we address this challenge using a combination of ab initio approaches, namely, a quantum treatment of IR spectrum using the ab initio WHBB water potential energy surface and a refined ab initio dipole moment surface. The quantum treatment is based on the embedded local monomer method, in which the three intramolecular modes of each embedded H2O monomer are fully coupled and also coupled singly to each of six intermolecular modes. The new dipole moment surface consists of a previous spectroscopically accurate 1-body dipole moment surface and a newly fitted ab initio intrinsic 2-body dipole moment. A detailed analysis of the new dipole moment surface in terms of the coordinate dependence of the effective atomic charges is done along with tests of it for the water dimer and prism hexamer double-harmonic spectra against direct ab initio calculations. The liquid configurations are taken from previous molecular dynamics calculations of Skinner and co-workers, using the TIP4P plus E3B rigid monomer water potential. The IR spectrum of water at 300 K in the range of 0-4000 cm(-1) is calculated and compared with experiment, using the ab initio WHBB potential and new ab initio dipole moment, the q-TIP4P/F potential, which has a fixed-charged description of the dipole moment, and the TTM3-F potential and dipole moment surfaces. The newly calculated ab initio spectrum is in very good agreement with experiment throughout the above spectral range, both in band positions and intensities. This contrasts to results with the other potentials and dipole moments, especially the fixed-charge q-TIP4P/F model, which gives unrealistic intensities. The calculated ab initio spectrum is analyzed by examining the contribution of various transitions to each band.
Institute of Scientific and Technical Information of China (English)
朱梦; 周辉; 程引会; 李宝忠; 吴伟; 李进玺; 马良; 赵墨
2013-01-01
深空核爆炸通过电偶极子和磁偶极子两种辐射机制产生电磁脉冲.本文具体分析了两种辐射模型产生电磁脉冲的物理机制,并估算了远处观察点的辐射电场.计算表明,电子以高斯波形出射时,百吨TNT当量爆炸在km量级范围内产生的电偶极子和磁偶极子辐射电场强度分别为kV/m和10 V/m量级.深空中地磁感应强度较弱,电子的角向运动相比初始方向运动是小量,因而磁偶极子的辐射强度远小于电偶极子的.%Electromagnetic pulse can be generated by the nuclear detonation in space via two radiation mechanisms.The electric dipole and magnetic dipole models were analyzed.The electric radiation in the far field generated by two models was calculated as well.Investigations show that in the case of one hundred TNT yield detonations,when electrons are emitted according to the Gaussian shape,two radiation models can give rise to the electric field in great distances with amplitudes of kV/m and tens of V/m,independently.Because the geomagnetic field in space is not strong and the electrons' angular motion is much weaker than the motion in the original direction,radiations from the magnetic dipole model are much weaker than those from the electric dipole model.
Dyer, Peter J; Cummings, Peter T
2006-10-14
We compare a new classical water model, which features Gaussian charges and polarizability (GCPM) with ab initio Car-Parrinello molecular dynamics (CPMD) simulations. We compare the total dipole moment, the total dipole moment distribution, and degree of hydrogen bonding at ambient to supercritical conditions. We also compared the total dipole moment calculated from both the electron density (partitioning the electron density among molecules based on a zero electron flux condition), and from the center of localized Wannier function centers (WFCs). Compared to CPMD, we found that GCPM overpredicts the dipole moment derived by partitioning the electron density and underpredicts that obtained from the WFCs, but exhibits similar trends and distribution of values. We also found that GCPM predicted similar degrees of hydrogen bonding compared to CPMD and has a similar structure.
DEFF Research Database (Denmark)
Madsen, G.K.H.; Krebs, Frederik C; Lebech, B.;
2000-01-01
The electron density distribution of the molecular pyroelectric material phosphangulene has been studied by multipolar modeling of X-ray diffraction data. The "in-crystal" molecular dipole moment has been evaluated to 4.7 D corresponding to a 42% dipole moment enhancement compared with the dipole...... pyroelectric coefficients has been introduced by combining the derived dipole moment with temperature-dependent measurements of the unit cell volume. The derived pyroelectric coefficient of 3.8(7)x 10(-6) Cm-2K-1 is in very good agreement with the measured pyroelectric coefficient of p = 3 +/- 1 x 10(-6) Cm-2...... K-1. This method for obtaining the pyroelectric coefficient uses information from the X-ray diffraction experiment alone and can be applied to much smaller crystals than traditional methods....
Lindsay, Sean Stephen
The shape, size, and composition of crystalline silicates observed in comet comae and external proto-planetary disks are indicative of the formation and evolution of the dust grains during the processes of planetary formation. In this dissertation, I present the 3 -- 40 mum absorption efficiencies( Qabs) of irregularly shaped forsterite crystals computed with the discrete dipole approximation (DDA) code DDSCAT developed by Draine and Flatau and run on the NASA Advanced Supercomputing facility Pleiades. An investigation of grain shapes ranging from spheroidal to irregular indicate that the strong spectral features from forsterite are sensitive to grain shape and are potentially degenerate with the effects of crystal solid state composition (Mg-content). The 10, 11, 18, 23, and 33.5 mum features are found to be the most crystal shape sensitive and should be avoided in determining Mg-content. The distinct spectral features for the three shape classes are connected with crystal formation environment using a condensation experiment by (Kobatake et al., 2008). The condensation experiment demonstrates that condensed forsterite crystal shapes are dependent on the condensation environmental temperature. I generate DDSCAT target analog shapes to the condensed crystal shapes. These analog shapes are represented by the three shape classes: 1) equant, 2) a, c-columns, and 3) b-shortened platelets. Each of these shape classes exhibit distinct spectral features that can be used to interpret grain shape characteristics from 8 --- 40 mum spectroscopy of astronomical objects containing crystalline silicates. Synthetic spectral energy distributions (SEDs) of the coma of Hale-Bopp at rh = 2.8 AU are generated by thermally modeling the flux contributions of 5 mineral species present in comets. The synthetic SEDs are constrained using a chi2- minimization technique. The mineral species are amorphous carbon, amorphous pyroxene, amorphous olivine, crystalline enstatite, and crystalline
Al-Sehemi, Abdullah G.; Pannipara, Mehboobali; Kalam, Abul
2017-01-01
A dihydroquinazolinone derivative 2-(2,4-Dimethoxy-phenyl)-2,3-dihydro-1H-quinazolin-4-one (1) was synthesized and characterized by 1H NMR, 13C NMR and FT-IR and its spectral, photophysical, intramolecular charge transfer characteristics were studied by absorption and emission spectroscopy. The compound exhibits significant changes in their photophysical properties depending on the solvent polarity. The observed bathochromic emission band and difference in Stokes shift on changing the polarity of the solvents clearly demonstrate the highly polar character of the excited state, which is also supported by the enhancement of dipole moment of the molecule upon photoexcitation. Solvatochromic shift methods based on Lippert-Mataga, Bakhshiev-Kawski and Reichardt's correlations were applied to calculate the ground, excited and change in dipole moments. The effect of solute-solvent interactions on compound 1 was studied using multi-parameter solvent polarity scales proposed by Kamlet-Taft and Catalan. The interactions of various metal ions on compound 1 were also studied using steady state fluorescence measurements. The emission profile reveals that it acts as on-off type fluorescent chemosensor for selective and sensitive detection of Hg2 + ions. Complexation stoichiometry and mechanism of quenching were determined from Benesi-Hildebrand and Stern-Volmer plot.
Yamanaka, Nodoka
2016-01-01
We calculate the electric dipole moment (EDM) of the deuteron in the standard model with $|\\Delta S| =1$ interactions by taking into account the $NN - \\Lambda N - \\Sigma N$ channel coupling. The two-body problem is solved with the Gaussian Expansion Method using the realistic Argonne $v18$ nuclear force and the $YN$ potential which can reproduce the binding energies of $^3_\\Lambda$H, $^3_\\Lambda$He, and $^4_\\Lambda$He. The $|\\Delta S| =1$ interbaryon potential is modeled by the one-meson exchange process. It is found that the deuteron EDM is modified by less than 10\\%, and the main contribution to this deviation is due to the polarization of the hyperon-nucleon channels. The effect of the $YN$ interaction is small, and treating $ \\Lambda N$ and $ \\Sigma N$ channels as free is a good approximation for the EDM of the deuteron.
Dipoles, unintentional antennas and EMC
Directory of Open Access Journals (Sweden)
Berend Danker
2008-01-01
Full Text Available Radiated emissions from equipment commonly originate from electronic circuits that act as electric dipoles created by the signal voltage between the signal conductors or as magnetic dipoles formed by the signal current flowing in a loop. Direct emission is mostly small, but circuits often couple to long conductors or large wiring loops which act as antennas and are efficient radiators. A comparable situation exists when short dipole antennas or small wiring loops receive ambient noise (susceptibility. Usually the amplitude of noise sources or the susceptibility of circuits is an invariable. The dipole strength increases with the distance between the conductors and the area. Shielding and proper grounding decreases the interaction via unintentional antennas. Short-circuiting and the insertion of lossy ferrite cores reduce the efficiency of unintentional antennas.
Cascade trailing-edge noise modeling using a mode-matching technique and the edge-dipole theory
Roger, Michel; François, Benjamin; Moreau, Stéphane
2016-11-01
An original analytical approach is proposed to model the broadband trailing-edge noise produced by high-solidity outlet guide vanes in an axial turbomachine. The model is formulated in the frequency domain and first in two dimensions for a preliminary assessment of the method. In a first step the trailing-edge noise sources of a single vane are shown to be equivalent to the onset of a so-called edge dipole, the direct field of which is expanded in a series of plane-wave modes. A criterion for the distance of the dipole to the trailing-edge and a scaling of its amplitude is defined to yield a robust model. In a second step the diffraction of each plane-wave mode is derived considering the cascade as an array of bifurcated waveguides and using a mode-matching technique. The cascade response is finally synthesized by summing the diffracted fields of all cut-on modes to yield upstream and downstream sound power spectral densities. The obtained spectral shapes are physically consistent and the present results show that upstream radiation is typically 3 dB higher than downstream radiation, which has been experimentally observed previously. Even though the trailing-edge noise sources are not vane-to-vane correlated their radiation is strongly determined by a cascade effect that consequently must be accounted for. The interest of the approach is that it can be extended to a three-dimensional annular configuration without resorting to a strip theory approach. As such it is a promising and versatile alternative to previously published methods.
Energy Technology Data Exchange (ETDEWEB)
Holanda, B A; Cordeiro, R C; Blak, A R, E-mail: bruna.holanda@usp.br, E-mail: renan.cordeiro@usp.br, E-mail: anablak@if.usp.br
2010-11-15
Dipole defects in gamma irradiated and thermally treated beryl (Be{sub 3}Al{sub 2}Si{sub 6}O{sub 18}) samples have been studied using the Thermally Stimulated Depolarization Currents (TSDC) technique. TSDC experiments were performed in pink (morganite), green (emerald), blue (aquamarine) and colourless (goshenite) natural beryl. TSDC spectra present dipole peaks at 190K, 220K, 280K and 310K that change after gamma irradiation and thermal treatments. In morganite samples, for thermal treatments between 700K and 1100K, the 280K peak increase in intensity and the band at 220K disappears. An increase of the 280K peak and a decrease of the 190K peak were observed in the TSDC spectra of morganite after a gamma irradiation of 25kGy performed after the thermal treatments. In the case of emerald samples, thermal treatments enhanced the 280K peak and gamma irradiation partially destroyed this band. The goshenite TSDC spectra present only one band at 280K that is not affected either by thermal treatments or by gamma irradiation. All the observed peaks are of dipolar origin because the intensity of the bands is linearly dependent on the polarization field, behaviour of dipole defects. The systematic study, by means of TSDC measurements, of ionizing irradiation effects and thermal treatments in these crystals makes possible a better understanding of the role played by the impurities in beryl crystals.
Fast electromagnetic modeling in cylindrically layered media excited by eccentred magnetic dipole
Nikitenko, Marina; Itskovich, Gregory B.; Seryakov, Alexander
2016-06-01
We developed a fast algorithm to calculate a response of cylindrically layered media excited by the vertical magnetic dipole eccentred with respect to the axis of symmetry. The algorithm calculates response in the range of frequencies typical for induction and dielectric logging. The media conductivity and dielectric constant are described by piecewise-constant functions. The corresponding boundary value problem is solved by method of separation of variables. Fourier transform is applied to Maxwell equations and boundary conditions to express field components through Fourier transforms of vertical components of an electrical and magnetic field. In addition, an expansion of vertical components into an infinite series with respect to angular harmonics is used to reduce the original problem to a series of 1-D problems that only depend on the radial coordinate. The solution to each 1-D radial problem for the angular harmonics is presented as a linear combination of modified Bessel functions. Finally, inverse Fourier transformation is applied to the angular harmonics of vertical components to derive electrical and magnetic field of the original boundary value problem. We provide detailed discussion on the elements that are critical for the numerical implementation of the algorithm: a proper normalization, convergence, and integration. Specifically, we show how to perform integration in the complex plane by avoiding intersection of the integration pass with the cuts located on the Riemann surface. Numerical results show the usefulness of the algorithm for solving inverse problems and for studying the effect of eccentricity in induction and dielectric logging.
Energy Technology Data Exchange (ETDEWEB)
Protsenko, I E; Uskov, A V; Krotova, K E [Lebedev Physical Institute, Leninsky prospect 53, Moscow (Russian Federation); O' Reilly, E P [Tyndall National Institute, ' Lee Maltings' , Prospect Row, Cork (Ireland)], E-mail: protsen@sci.lebedev.ru, E-mail: protsenk@gmail.com
2008-03-15
Theoretically predicted 'dipole lasing', i.e., spontaneous excitation of coherent metal nano-particle dipole oscillations through interaction with a quantum-dot two-level system subject to population inversion is demonstrated. Equations for dipole lasing are the same as equations for ordinary laser, where the dipole momentum of nano-particle stands for the electromagnetic field cavity mode. Dipole lasing frequency corresponds to the localized plasmon resonance of the nano-particle. Dipole momentum of nano-particle leads to coherent dipole radiation. Optical cavity is not necessary, the size of the dipole laser can be smaller than the optical wavelength, i.e. it is dipole nano-laser. Threshold conditions and optical bistability in dipole nano-lasers are considered.
Giant Primeval Magnetic Dipoles
Thompson, Christopher
2017-07-01
Macroscopic magnetic dipoles are considered cosmic dark matter. Permanent magnetism in relativistic field structures can involve some form of superconductivity, one example being current-carrying string loops (“springs”) with vanishing net tension. We derive the cross-section for free classical dipoles to collide, finding it depends weakly on orientation when mutual precession is rapid. The collision rate of “spring” loops with tension { T }˜ {10}-8{c}4/G in galactic halos approaches the measured rate of fast radio bursts (FRBs) if the loops compose most of the dark matter. A large superconducting dipole (LSD) with mass ˜1020 g and size ˜1 mm will form a ˜100 km magnetosphere moving through interstellar plasma. Although hydromagnetic drag is generally weak, it is strong enough to capture some LSDs into long-lived rings orbiting supermassive black holes (SMBHs) that form by the direct collapse of massive gas clouds. Repeated collisions near young SMBHs could dominate the global collision rate, thereby broadening the dipole mass spectrum. Colliding LSDs produce tiny, hot electromagnetic explosions. The accompanying paper shows that these explosions couple effectively to propagating low-frequency electromagnetic modes, with output peaking at 0.01-1 THz. We describe several constraints on, and predictions of, LSDs as cosmic dark matter. The shock formed by an infalling LSD triggers self-sustained thermonuclear burning in a C/O (ONeMg) white dwarf (WD) of mass ≳1 M ⊙ (1.3 M ⊙). The spark is generally located off the center of the WD. The rate of LSD-induced explosions matches the observed rate of Type Ia supernovae.
Dipole-Dipole Interactions of Charged Magnetic Grains
Perry, Jonathan; Hyde, Truell
2010-01-01
The interaction between dust grains is an important process in fields as diverse as planetesimal formation or the plasma processing of silicon wafers into computer chips. This interaction depends in large part on the material properties of the grains, for example whether the grains are conducting, non-conducting, ferrous or non-ferrous. This work considers the effects that electrostatic and magnetic forces, alone or in combination, can have on the coagulation of dust in various environments. A numerical model is used to simulate the coagulation of charged, charged-magnetic and magnetic dust aggregates formed from ferrous material and the results are compared to each other as well as to those from uncharged, non-magnetic material. The interactions between extended dust aggregates are also examined, specifically looking at how the arrangement of charge over the aggregate surface or the inclusion of magnetic material produces dipole-dipole interactions. It will be shown that these dipole-dipole interactions can ...
Dinh Dang, N.; Ciemala, M.; Kmiecik, M.; Maj, A.
2013-05-01
The line shapes of giant dipole resonance (GDR) in the decay of the compound nucleus 88Mo, which is formed after the fusion-evaporation reaction 48Ti + 40Ca at various excitation energies E* from 58 to 308 MeV, are generated by averaging the GDR strength functions predicted within the phonon damping model (PDM) using the empirical probabilities for temperature and angular momentum. The average strength functions are compared with the PDM strength functions calculated at the mean temperature and mean angular momentum, which are obtained by averaging the values of temperature and angular momentum using the same temperature and angular momentum probability distributions, respectively. It is seen that these two ways of generating the GDR linear line shape yield very similar results. It is also shown that the GDR width approaches a saturation at angular momentum J≥ 50 ℏ at T=4 MeV and at J≥ 70 ℏ at any T.
Dang, N Dinh; Kmiecik, M; Maj, A
2013-01-01
The line shapes of giant dipole resonance (GDR) in the decay of the compound nucleus $^{88}$Mo, which is formed after the fusion-evaporation reaction $^{48}$Ti + $^{40}$Ca at various excitation energies $E^{*}$ from 58 to 308 MeV, are generated by averaging the GDR strength functions predicted within the phonon damping model (PDM) using the empirical probabilities for temperature and angular momentum. The average strength functions are compared with the PDM strength functions calculated at the mean temperature and mean angular momentum, which are obtained by averaging the values of temperature and angular momentum using the same temperature and angular-momentum probability distributions, respectively. It is seen that these two ways of generating the GDR linear line shape yield very similar results. It is also shown that the GDR width approaches a saturation at angular momentum $J\\geq$ 50$\\hbar$ at $T=$ 4 MeV and at $J\\geq$ 70$\\hbar$ at any $T$.
Simplified approach to double jumps for fluorescing dipole-dipole interacting atoms
Hannstein, V; Hannstein, Volker; Hegerfeldt, Gerhard C.
2006-01-01
A simplified scheme for the investigation of cooperative effects in the quantum jump statistics of small numbers of fluorescing atoms and ions in a trap is presented. It allows the analytic treatment of three dipole-dipole interacting four-level systems which model the relevant level scheme of Ba+ ions. For the latter, a huge rate of double and triple jumps was reported in a former experiment and the huge rate was attributed to the dipole-dipole interaction. Our theoretical results show that the effect of the dipole-dipole interaction on these rates is at most 5% and that for the parameter values of the experiment there is practically no effect. Consequently it seems that the dipole-dipole interaction can be ruled out as a possible explanation for the huge rates reported in the experiment.
Dipole Engineering for Conducting Polymers
McClain, William Edward
A method for the growth of a TiO2 adhesion layer on PEDOT:PSS (poly[3,4- ethylenedioxythiophene]: poly[styrenesulfonate]) and for further functionalization with self-assembled monolayers of phosphonates (SAMPs) was developed. The TiO2 adhesion layer was grown via chemical vapor deposition using a titanium(IV) t-butoxide precursor, and was characterized by goniometry and X-ray photoelectron spectroscopy. TiO 2 grown on a model system, H-terminated silicon, indicated that the surface was t-butoxide terminated. Phenylphosphonic acids were synthesized with a variety of molecular dipoles and were used to change the work function of PEDOT:PSS through the formation of an aggregate surface dipole. Good correlation was found between the z-component of the molecular dipole and the change in work function, indicating that the film was well-ordered and dense. The magnitude of the changes in work function and goniometry measurements were similar to measurements on ITO, a substrate on which phosphonates form well-ordered monolayers. As-grown PEDOT:PSS/TiO 2 electrodes showed a lower work function compared to PEDOT:PSS, which is attributed to residual t-butoxide groups on the TiO 2 surface. UPS measurements revealed that reductions in work function in the modified electrodes lowered the difference in energy between the Fermi energy (EF) of the conducting polymer and the LUMO of PCBM ([6,6]-phenyl-C 61-butyric acid methyl ester). A reduction of this energy difference should translate into increased electron injection in electron-only diodes; however, devices with modified electrodes showed decreased current densities. UPS/IPES measurements show that TiO2 grown using this method has a much larger band gap than bulk or nanocrystalline TiO2, which is likely responsible for this decrease in device currents. At high bias, device currents increase dramatically, and the effects of the phosphonates or t-butoxide terminated TiO2 vanish. This is attributed to a reduction of the TiO2 to
Current Challenges in Dynamo Modeling
Glatzmaier, G. A.
2001-12-01
Three-dimensional, dynamically self-consistent, numerical simulations have been used for two decades to study the generation of global magnetic fields in the deep fluid interiors of planets and stars. In particular, the number of geodynamo models has increased significantly within the last five years. These simulations of magnetic field generation by laminar convection have provided considerable insight to the dynamo process and have produced large-scale fields similar to those observed. However, no global convective dynamo simulation has yet been able to afford the spatial resolution required to simulate turbulent convection, which surely must exist in these low-viscosity fluids. They have all employed greatly enhanced eddy diffusivities to stabilize the low resolution numerical solutions and crudely account for the transport and mixing by the unresolved turbulence. A grand challenge for the next generation of geodynamo models is to produce a simulation with the thermal and viscous (eddy) diffusivities set no larger than the actual magnetic diffusivity of the Earth's fluid core (2 m2/s), while using the core's dimensions, mass, rotation rate and heat flow. This would correspond to the Ekman and magnetic Ekman numbers both set to 10-9 and the Rayleigh number being many orders of magnitude greater than critical. Dynamo models for stars and planets present an additional complication: the large variation of density with radius. A grand challenge for the next generation of these models is to reach similarly low Ekman numbers and high Rayleigh numbers with a density that decreases by at least three orders of magnitude from the base of the convection zone to the model's outer boundary. The advances in numerical methods and massively parallel computing needed to meet these challenges will be discussed.
RHIC spin flipper AC dipole controller
Energy Technology Data Exchange (ETDEWEB)
Oddo, P.; Bai, M.; Dawson, C.; Gassner, D.; Harvey, M.; Hayes, T.; Mernick, K.; Minty, M.; Roser, T.; Severino, F.; Smith, K.
2011-03-28
The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to and dynamically tune the magnets. The current implementation and results will be presented. Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store. The spin flipper system consists of four DC-dipole magnets (spin rotators) and five AC-dipole magnets. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Operationally the AC-dipoles form two swept frequency bumps that minimize the effect of the AC-dipole dipoles outside of the spin flipper. Both AC bumps operate at the same frequency, but are phase shifted from each other. The AC-dipoles therefore require precise control over amplitude and phase making the implementation of the AC-dipole controller the central challenge.
Standard model contribution to the electric dipole moment of the deuteron, $^3$H, and $^3$He nuclei
Yamanaka, Nodoka
2015-01-01
We calculate for the first time the electric dipole moment (EDM) of the deuteron, $^3$H, and $^3$He nuclei generated by the one-meson exchange CP-odd nuclear force in the standard model. The effective $|\\Delta S| = 1$ four-quark operators are matched to the $|\\Delta S| = 1$ standard model processes involving the CP phase of the Cabibbo-Kobayashi-Maskawa matrix at the electroweak scale and run down to the hadronic scale $\\mu = 1$ GeV according to the renormalization group evolution in the next-to-leading logarithmic order. At the hadronic scale, the hadron matrix elements are modeled in the factorization approach. We then obtain the one-meson (pion, eta meson, and kaon) exchange CP-odd nuclear force, which is the combination of the $|\\Delta S| = 1$ meson-baryon vertices which issue from the penguin operator and the hyperon-nucleon transition. From this CP-odd nuclear force, the nuclear EDM is calculated with the realistic Argonne $v18$ interaction and the CP-odd nuclear force using the Gaussian expansion metho...
Which dipole are you studying in lab?
Binder, P.-M.; Tate, Reuben B.; Crowder, Callie K.
2017-01-01
We explore the similarities and differences between the electric dipole studied in introductory physics and the purportedly equivalent elementary experiment in which the electric potential is measured on a conductive sheet as a current flows. The former is a three-dimensional electrostatic dipole while the latter is a two-dimensional steady-state dipole. In spite of these differences, and as shown in this work, the potentials due to these dipoles look very similar. This may be misleading to either students or unaware instructors.
DEFF Research Database (Denmark)
Gammelmark, Søren; Zinner, Nikolaj Thomas
2013-01-01
We study polar molecules with long-range dipole-dipole interactions confined to move on a two-leg ladder for different orientations of the molecular dipole moments with respect to the ladder. Matrix product states are employed to calculate the many-body ground state of the system as function...... of lattice filling fractions, perpendicular hopping between the legs, and dipole interaction strength. We show that the system exhibits zig-zag ordering when the dipolar interactions are predominantly repulsive. As a function of dipole moment orientation with respect to the ladder, we find...... that there is a critical angle at which ordering disappears. This angle is slightly larger than the angle at which the dipoles are non-interacting along a single leg. This behavior should be observable using current experimental techniques....
Mineev, V. P.
2009-01-01
The roton excitation in the superfluid He-4 does not possess a stationary dipole moment. However, a roton has an instantaneous dipole moment, such that at any given moment one can find it in the state either with positive or with negative dipole moment projection on its momentum direction. The instantaneous value of electric dipole moment of roton excitation is evaluated. The result is in reasonable agreement with recent experimental observation of the splitting of microwave resonance absorpt...
How to Introduce the Magnetic Dipole Moment
Bezerra, M.; Kort-Kamp, W. J. M.; Cougo-Pinto, M. V.; Farina, C.
2012-01-01
We show how the concept of the magnetic dipole moment can be introduced in the same way as the concept of the electric dipole moment in introductory courses on electromagnetism. Considering a localized steady current distribution, we make a Taylor expansion directly in the Biot-Savart law to obtain, explicitly, the dominant contribution of the…
Direct summation of dipole-dipole interactions using the Wolf formalism.
Stenqvist, Björn; Trulsson, Martin; Abrikosov, Alexei I; Lund, Mikael
2015-07-07
We present an expanded Wolf formalism for direct summation of long-range dipole-dipole interactions and rule-of-thumbs how to choose optimal spherical cutoff (Rc) and damping parameter (α). This is done by comparing liquid radial distribution functions, dipole-dipole orientation correlations, particle energies, and dielectric constants, with Ewald sums and the Reaction field method. The resulting rule states that ασ 3 for reduced densities around ρ(∗) = 1 where σ is the particle size. Being a pair potential, the presented approach scales linearly with system size and is applicable to simulations involving point dipoles such as the Stockmayer fluid and polarizable water models.
Gontijo, R. G.; Cunha, F. R.
2017-06-01
This work describes a numerical model to compute the translational and rotational motion of N spherical magnetic particles settling in a quiescent viscous fluid under creeping flow condition. The motion of the particles may be produced by the action of gravitational forces, Brownian thermal fluctuations, magnetic dipole-dipole interactions, external magnetic field, and hydrodynamic interactions. In order to avoid particle overlap, we consider a repulsive force based on a variation of a screened-Coulomb potential mixed with Hertz contact forces. The inertia of the particles is neglected so that a mobility approach to describe the hydrodynamic interactions is used. The magnetic dipoles are fixed with respect to the particles themselves. Thus they can only interact magnetically between them and with an external applied magnetic field. Therefore the effect of magnetic field moment rotation relative to the particle as a consequence of a finite amount of particle anisotropy is neglected in this work. On the other hand, the inclusion of particle viscous hydrodynamic interactions and dipolar interactions is considered in our model. Both long-range hydrodynamic and magnetic interactions are accounted by a sophisticated technique of lattice sums. This work considers several possibilities of periodic and non-periodic particle interaction schemes. This paper intends to show the benefits and disadvantages of the different approaches, including a hybrid possibility of computing periodic and non-periodic particle interactions. The well-known mean sedimentation velocity and the equilibrium magnetization of the suspension are computed to validate the numerical scheme. The comparison is performed with the existent theoretical models valid for dilute suspensions and several empirical correlations available in the current literature. In the presence of dipole-dipole particle interactions, the simulations show a non-monotonic behavior of the mean sedimentation velocity as the particle
Modeling of Current Transformers Under Saturation Conditions
Directory of Open Access Journals (Sweden)
Martin Prochazka
2006-01-01
Full Text Available During a short circuit the input signal of the relay can be distort by the magnetic core saturation of the current transformer. It is useful to verify the behavior of CT by a mathematical model. The paper describes one phase and three phase models and it presents some methods of how to analyze and classify a deformed secondary current
Dipole model analysis of F2cc¯${m{F}}_2^{{m{car c}}} $ derived from the new D* data in DIS at HERA
Directory of Open Access Journals (Sweden)
Luszczak Agnieszka
2012-12-01
Full Text Available I analyse the new D* deep inelastic scattering data from HERA with the help of dipole models. I calculate F2cc¯${m{F}}_2^{{m{car c}}} $ from the GBW [1] and BGK [2] saturation models. I compare results with the last values determined by H1 at low Q2. I find good agreement with the data.
Standard model contribution to the electric dipole moment of the deuteron, 3H, and 3He nuclei
Yamanaka, Nodoka; Hiyama, Emiko
2016-02-01
We calculate for the first time the electric dipole moment (EDM) of the deuteron, 3H, and 3He nuclei generated by the one-meson exchange CP-odd nuclear force in the standard model. The effective |Δ S| = 1 four-quark operators are matched to the |Δ S| = 1 standard model processes involving the CP phase of the Cabibbo-Kobayashi-Maskawa matrix at the electroweak scale and run down to the hadronic scale μ = 1 GeV according to the renormalization group evolution in the next-to-leading logarithmic order. At the hadronic scale, the hadron matrix elements are modeled in the factorization approach. We then obtain the one-meson (pion, eta meson, and kaon) exchange CP-odd nuclear force, which is the combination of the |Δ S| = 1 meson-baryon vertices which issue from the penguin operator and the hyperon-nucleon transition. From this CP-odd nuclear force, the nuclear EDM is calculated with the realistic Argonne v18 interaction and the CP-odd nuclear force using the Gaussian expansion method. It is found that the EDMs of light nuclear systems are of order O (10-31) e cm. We also estimate the standard model contribution to other hadronic CP violating observables such as the EDMs of 6Li, 9Be nuclei, and the atomic EDMs of 129Xe, 199Hg, 211Rn, and 225Ra generated through the nuclear Schiff moment. We then analyze the source of theoretical uncertainties and show some possible ways to overcome them.
Axion Induced Oscillating Electric Dipole Moments
Hill, Christopher T
2015-01-01
The axion electromagnetic anomaly induces an oscillating electric dipole for any static magnetic dipole. Static electric dipoles do not produce oscillating magnetic moments. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency $m_a$ and strength $\\sim 10^{-32}$ e-cm, two orders of magnitude above the nucleon, and within four orders of magnitude of the present standard model DC limit. This may suggest sensitive new experimental venues for the axion dark matter search.
Ambjørndalen, Sara; Verweij, Arjan
The Large Hadron Collider (LHC) utilizes high-field superconducting Main Dipole Magnets that bend the trajectory of the beam. The LHC ring is electrically divided into eight octants, each allocating a 7 km chain of 154 Main Dipole Magnets. Dedicated de- tection and protection systems prevent irreversible magnet damage caused by quenches. Quench is a local transition from the superconducting to the normal conducting state. Triggering of such systems, along with other failure scenarios, result in fast transient phenomena. In order to analyze the consequence of such electrical transients and failures in the dipole chain, one needs a circuit model that is validated against measurements. Currently, there exists an equivalent circuit of the Main Dipole Magnet resolved at an aperture level. Each aperture model takes into account the dynamic effects occurring in the magnets, trough a lossy-inductance model and parasitic capacitances to ground. At low frequencies the Main Dipole Magnet behaves as a linear inductor. Ca...
Magnetic flux transport and the sun's dipole moment - New twists to the Babcock-Leighton model
Wang, Y.-M.; Sheeley, N. R., Jr.
1991-01-01
The mechanisms that give rise to the sun's large-scale poloidal magnetic field are explored in the framework of the Babcock-Leighton (BL) model. It is shown that there are in general two quite distinct contributions to the generation of the 'alpha effect': the first is associated with the axial tilts of the bipolar magnetic regions as they erupt at the surface, while the second arises through the interaction between diffusion and flow as the magnetic flux is dispersed over the surface. The general relationship between flux transport and the BL dynamo is discussed.
Finite Bias Calculations to Model Interface Dipoles in Electrochemical Cells at the Atomic Scale
DEFF Research Database (Denmark)
Hansen, Martin Hangaard; Jin, Chengjun; Thygesen, Kristian Sommer
2016-01-01
The structure of an electrochemical interface is not determined by any external electrostatic field, but rather by external chemical potentials. This paper demonstrates that the electric double layer should be understood fundamentally as an internal electric field set up by the atomic structure t...... to satisfy the thermodynamic constraints imposed by the environment. This is captured by the generalized computational hydrogen electrode model, which enables us to make efficient first-principles calculations of atomic scale properties of the electrochemical interface.......The structure of an electrochemical interface is not determined by any external electrostatic field, but rather by external chemical potentials. This paper demonstrates that the electric double layer should be understood fundamentally as an internal electric field set up by the atomic structure...
Integral Measurement of Dipole Prototype of CSR
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The dipole prototype is C type used as bending magnet of the injection beam line in CSR, and acts as a model of the dipoles in the CSR main ring simultaneously. The designed relative uniformity of good field is 0.001 in 100 mm width. The results of the local distribution and transfunction at transverse profile measured
Numerical modeling of transformer inrush currents
Cardelli, E.; Faba, A.
2014-02-01
This paper presents an application of a vector hysteresis model to the prediction of the inrush current due the arbitrary initial excitation of a transformer after a fault. The approach proposed seems promising in order to predict the transient overshoot in current and the optimal time to close the circuit after the fault.
Numerical modeling of transformer inrush currents
Energy Technology Data Exchange (ETDEWEB)
Cardelli, E. [Department of Industrial Engineering, University of Perugia, I-06125 Perugia (Italy); Center for Electric and Magnetic Applied Research (Italy); Faba, A., E-mail: faba@unipg.it [Department of Industrial Engineering, University of Perugia, I-06125 Perugia (Italy); Center for Electric and Magnetic Applied Research (Italy)
2014-02-15
This paper presents an application of a vector hysteresis model to the prediction of the inrush current due the arbitrary initial excitation of a transformer after a fault. The approach proposed seems promising in order to predict the transient overshoot in current and the optimal time to close the circuit after the fault.
Quench protection studies of 11T 2-in-1 Nb$_{3}$Sn dipole models for LHC upgrades
Zlobin, AV; Nobrega, F; Novitski, I; Karppinen, M
2014-01-01
CERN and FNAL are developing 11 T Nb3Sn dipole magnets for the LHC collimation system upgrade. Due to the large stored energy, protection of these magnets during a quench is a challenging problem. This paper reports the results of experimental studies of key quench protection parameters including longitudinal and radial quench propagation in the coil, coil heating due to a quench, and energy extraction and quench-back effect. The studies were performed using a 1 m long 11 T Nb3Sn dipole coil tested in a magnetic mirror configuration.
Searching for electric dipole moments
Jungmann, Klaus
2013-01-01
Searches for a permanent Electric Dipole Moment (EDM) of a fundamental particle provide a wide window for the discovery of potential New Physics. Within todays Standard Model in particle physics the well established violation of CP symmetry gives rise to EDMs which are several orders of magnitude be
Meijs, J.W.H.; Bosch, F.G.C.; Peters, M.J.; Lopes da silva, F.H.
1987-01-01
The magnetic field distribution around the head is simulated using a realistically shaped compartment model of the head. The model is based on magnetic resonance images. The 3 compartments describe the brain, the skull and the scalp. The source is represented by a current dipole situated in the
Color dipole chain and its hadronization in pp collision
Institute of Scientific and Technical Information of China (English)
赵晋全; 王群; 谢去病
1995-01-01
High energy pp collision is dealt with by double-string model. Each string corresponds to one initial color dipole which will radiate gluons to form color dipole chain. Such gluon radiation process is described by color dipole model. According to the quark combination rule, the total multiplicity formulae for calculating primary meson and baryon of one dipole chain are presented- The calculated yields of various final hadrons in energy range =53- 1 800GeV agree well with available data.
High-field dipoles for future accelerators
Energy Technology Data Exchange (ETDEWEB)
Wipf, S.L.
1984-09-01
This report presents the concept for building superconducting accelerator dipoles with record high fields. Economic considerations favor the highest possible current density in the windings. Further discussion indicates that there is an optimal range of pinning strength for a superconducting material and that it is not likely for multifilamentary conductors to ever equal the potential performance of tape conductors. A dipole design with a tape-wound, inner high-field winding is suggested. Methods are detailed to avoid degradation caused by flux jumps and to overcome problems with the dipole ends. Concerns for force support structure and field precision are also addressed. An R and D program leading to a prototype 11-T dipole is outlined. Past and future importance of superconductivity to high-energy physics is evident from a short historical survey. Successful dipoles in the 10- to 20-T range will allow interesting options for upgrading present largest accelerators.
Yamanaka, Nodoka; Kubota, Takahiro
2012-01-01
We reexamine the R-parity violating contribution to the fermion electric and chromo-electric dipole moments (EDM and cEDM) in the two-loop diagrams. It is found that the leading Barr-Zee type two-loop contribution is smaller than the result found in previous works, and that EDM experimental data provide looser limits on RPV couplings.
Estimates of current debris from flux models
Energy Technology Data Exchange (ETDEWEB)
Canavan, G.H.
1997-01-01
Flux models that balance accuracy and simplicity are used to predict the growth of space debris to the present. Known and projected launch rates, decay models, and numerical integrations are used to predict distributions that closely resemble the current catalog-particularly in the regions containing most of the debris.
AUTHOR|(CDS)2067087
In one of its acceptation, the word quench is synonym of destruction. And this is even more consistent with reality in the case of the Large Hadron Collider dipole magnets, whose magnetic field and stored energy are unprecedented: the uncontrolled transition from the superconducting to the resistive state can be the origin of dramatic events. This is why the protection of magnets is so important, and why so many studies and investigations have been carried out on quench origin. The production, cold testing and installation of the 1232 arc dipole magnets is completed. They have fulfilled all the requirements and the operation reliability of these magnets has already been partially confirmed. From an academic standpoint, nevertheless, the anomalous mechanical behaviour, which was sometimes observed during power tests, has not yet been given a clear explanation. The work presented in this thesis aims at providing an instrument to better understand the reasons for such anomalies, by means of finite element modell...
Energy Technology Data Exchange (ETDEWEB)
Sharma, M. [Dept. of Physics and Astro-Physics, Univ. of Delhi (India); Govind, N.; Pratap, A. [Condense Matter Theory Group, National Physical Lab., New Delhi (India); Ajay; Tripathi, R.S. [Dept. of Physics, G.B. Pant Univ. of Agriculture and Technology, Pantnagar (India)
2001-07-01
In the present paper, we report the role of dipole-dipole interaction on the magnetic dynamics of single layer antiferromagnets. For this, the model Hamiltonian includes the exchange Heisenberg Hamiltonian as well as dipole-dipole interactions. Within the linear spin-wave theory, we employ the double time Green's function technique to obtain expressions for the spin wave dispersion, sublattice magnetization and the magnetic contribution to specific heat as a function of various parameters of the model Hamiltonian. We observe through numerical calculations that in the absence of anisotropy in exchange couplings the dipole-dipole interaction works as an anisotropy and sustains the magnetization even in a pure 2D system. (orig.)
Dynamic Dipole-Dipole Interactions between Excitons in Quantum Dots of Different Sizes
DEFF Research Database (Denmark)
Matsueda, Hideaki; Leosson, Kristjan; Xu, Zhangcheng
2005-01-01
Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes.......Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes....
Dynamic Dipole-Dipole Interactions between Excitons in Quantum Dots of Different Sizes
DEFF Research Database (Denmark)
Matsueda, Hideaki; Leosson, Kristjan; Xu, Zhangcheng;
2005-01-01
Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes.......Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes....
Quench Protection Studies of the 11-T $Nb_3Sn$ Dipole for LHC Upgrades
Izquierdo Bermudez, Susana; BAJAS, Hugues; Bajko, Marta; Bordini, Bernardo; Bottura, Luca; Chlachidze, Guram; Karppinen, Mikko; Rysti, Juho; Savary, Frederic; Willering, Gerard; Zlobin, Alexander
2016-01-01
The planned upgrade of the LHC collimation system foresees additional collimators to be installed in the dispersion suppressor areas. Fermilab and CERN are developing an 11 T Nb3Sn dipole to replace some 8.33 T-15-m-long Nb-Ti LHC main dipoles providing longitudinal space for the collimators. In case of a quench, the large stored energy and the low copper stabilizer fraction make the protection of the 11 T Nb3Sn dipoles challenging. This paper presents the results of quench protection analysis, including quench protection heater design and efficiency, quench propagation and coil heating. The numerical results are compared with the experimental data from the 2-m-long Nb3Sn dipole models. The validated model is used to predict the current decay and hot spot temperature under operating conditions in the LHC and the presently foreseen magnet protection scheme is discussed.
Kaneko, Daijiro
2015-04-01
Crop-monitoring systems with the unit of carbon-dioxide sequestration for environmental issues related to climate adaptation to global warming have been improved using satellite-based photosynthesis and meteorological conditions. Early management of crop status is desirable for grain production, stockbreeding, and bio-energy providing that the seasonal climate forecasting is sufficiently accurate. Incorrect seasonal forecasting of crop production can damage global social activities if the recognized conditions are unsatisfied. One cause of poor forecasting related to the atmospheric dynamics at the Earth surface, which reflect the energy budget through land surface, especially the oceans and atmosphere. Recognition of the relation between SST anomalies (e.g. ENSO, Atlantic Niño, Indian dipoles, and Ningaloo Niño) and crop production, as expressed precisely by photosynthesis or the sequestrated-carbon rate, is necessary to elucidate the mechanisms related to poor production. Solar radiation, surface air temperature, and water stress all directly affect grain vegetation photosynthesis. All affect stomata opening, which is related to the water balance or definition by the ratio of the Penman potential evaporation and actual transpiration. Regarding stomata, present data and reanalysis data give overestimated values of stomata opening because they are extended from wet models in forests rather than semi-arid regions commonly associated with wheat, maize, and soybean. This study applies a complementary model based on energy conservation for semi-arid zones instead of the conventional Penman-Monteith method. Partitioning of the integrated Net PSN enables precise estimation of crop yields by modifying the semi-closed stomata opening. Partitioning predicts production more accurately using the cropland distribution already classified using satellite data. Seasonal crop forecasting should include near-real-time monitoring using satellite-based process crop models to avoid
Behavioral modeling of Digitally Adjustable Current Amplifier
Josef Polak; Lukas Langhammer; Jan Jerabek
2015-01-01
This article presents the digitally adjustable current amplifier (DACA) and its analog behavioral model (ABM), which is suitable for both ideal and advanced analyses of the function block using DACA as active element. There are four levels of this model, each being suitable for simulation of a certain degree of electronic circuits design (e.g. filters, oscillators, generators). Each model is presented through a schematic wiring in the simulation program OrCAD, including a description of equat...
Simulation of Gravity Currents Using VOF Model
Institute of Scientific and Technical Information of China (English)
邹建锋; 黄钰期; 应新亚; 任安禄
2002-01-01
By the Volume of Fluid (VOF) multiphase flow model two-dimensional gravity currents with three phases including air are numerically simulated in this article. The necessity of consideration of turbulence effect for high Reynolds numbers is demonstrated quantitatively by LES (the Large Eddy Simulation) turbulence model. The gravity currents are simulated for h ≠ H as well as h = H, where h is the depth of the gravity current before the release and H is the depth of the intruded fluid. Uprising of swell occurs when a current flows horizontally into another lighter one for h ≠ H. The problems under what condition the uprising of swell occurs and how long it takes are considered in this article. All the simulated results are in reasonable agreement with the experimental results available.
Directory of Open Access Journals (Sweden)
B. Scarnato
2012-10-01
Full Text Available According to recent studies, internal mixing of black carbon (BC with other aerosol materials in the atmosphere alters its aggregate shape, absorption of solar radiation, and radiative forcing. These mixing state effects are not yet fully understood. In this study, we characterize the morphology and mixing state of bare BC and BC internally mixed with sodium chloride (NaCl using electron microscopy and examine the sensitivity of optical properties to BC mixing state and aggregate morphology using a discrete dipole approximation model (DDSCAT. DDSCAT predicts a higher mass absorption coefficient, lower single scattering albedo (SSA, and higher absorption Angstrom exponent (AAE for bare BC aggregates that are lacy rather than compact. Predicted values of SSA at 550 nm range between 0.18 and 0.27 for lacy and compact aggregates, respectively, in agreement with reported experimental values of 0.25 ± 0.05. The variation in absorption with wavelength does not adhere precisely to a power law relationship over the 200 to 1000 nm range. Consequently, AAE values depend on the wavelength region over which they are computed. In the 300 to 550 nm range, AAE values ranged in this study from 0.70 for compact to 0.95 for lacy aggregates. The SSA of BC internally mixed with NaCl (100–300 nm in radius is higher than for bare BC and increases with the embedding in the NaCl. Internally mixed BC SSA values decrease in the 200–400 nm wavelength range, a feature also common to the optical properties of dust and organics. Linear polarization features are also predicted in DDSCAT and are dependent on particle morphology. The bare BC (with a radius of 80 nm presents in the linear polarization a bell shape feature, which is a characteristic of the Rayleigh regime (for particles smaller than the wavelength of incident radiation. When BC is internally mixed with NaCl (100–300 nm in radius, strong depolarization features for near-VIS incident radiation are evident
Directory of Open Access Journals (Sweden)
James Jaeyoon Jun
Full Text Available In order to survive, animals must quickly and accurately locate prey, predators, and conspecifics using the signals they generate. The signal source location can be estimated using multiple detectors and the inverse relationship between the received signal intensity (RSI and the distance, but difficulty of the source localization increases if there is an additional dependence on the orientation of a signal source. In such cases, the signal source could be approximated as an ideal dipole for simplification. Based on a theoretical model, the RSI can be directly predicted from a known dipole location; but estimating a dipole location from RSIs has no direct analytical solution. Here, we propose an efficient solution to the dipole localization problem by using a lookup table (LUT to store RSIs predicted by our theoretically derived dipole model at many possible dipole positions and orientations. For a given set of RSIs measured at multiple detectors, our algorithm found a dipole location having the closest matching normalized RSIs from the LUT, and further refined the location at higher resolution. Studying the natural behavior of weakly electric fish (WEF requires efficiently computing their location and the temporal pattern of their electric signals over extended periods. Our dipole localization method was successfully applied to track single or multiple freely swimming WEF in shallow water in real-time, as each fish could be closely approximated by an ideal current dipole in two dimensions. Our optimized search algorithm found the animal's positions, orientations, and tail-bending angles quickly and accurately under various conditions, without the need for calibrating individual-specific parameters. Our dipole localization method is directly applicable to studying the role of active sensing during spatial navigation, or social interactions between multiple WEF. Furthermore, our method could be extended to other application areas involving dipole
Technology of superconducting accelerator dipoles
Energy Technology Data Exchange (ETDEWEB)
Hassenzahl, W.V.; Meuser, R.B.; Taylor, C.
1983-06-01
We discuss accelerator dipoles and their characteristics. Other types of magnets, in particular bubble chamber magnets have been quite successful. Their performance is based on cryogenic stability which is addressed only briefly in this chapter. This type of stability is not available to the accelerator designer because of the large quantities of copper or other stabilizer that would reduce the current density in the windings to an unacceptably low value.
On the integrability of halo dipoles in gravity
Vieira, Werner M.; Letelier, Patricio S.
1997-01-01
We stress that halo dipole components are nontrivial in core-halo systems in both Newton's gravity and General Relativity. To this end, we extend a recent exact relativistic model to include also a halo dipole component. Next, we consider orbits evolving in the inner vacuum between a monopolar core and a pure halo dipole and find that, while the Newtonian dynamics is integrable, its relativistic counterpart is chaotic. This shows that chaoticity due only to halo dipoles is an intrinsic relati...
Directory of Open Access Journals (Sweden)
Takamasa Arakawa
Full Text Available Molecular dynamics (MD simulations of a double-stranded DNA with explicit water and small ions were performed with the zero-dipole summation (ZD method, which was recently developed as one of the non-Ewald methods. Double-stranded DNA is highly charged and polar, with phosphate groups in its backbone and their counterions, and thus precise treatment for the long-range electrostatic interactions is always required to maintain the stable and native double-stranded form. A simple truncation method deforms it profoundly. On the contrary, the ZD method, which considers the neutralities of charges and dipoles in a truncated subset, well reproduced the electrostatic energies of the DNA system calculated by the Ewald method. The MD simulations using the ZD method provided a stable DNA system, with similar structures and dynamic properties to those produced by the conventional Particle mesh Ewald method.
Radiating dipoles in photonic crystals
Busch, Kurt; Vats, Nipun; John, Sajeev; Sanders, Barry C.
2000-01-01
The radiation dynamics of a dipole antenna embedded in a Photonic Crystal are modeled by an initially excited harmonic oscillator coupled to a non--Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the Photonic Crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra ar...
Axion induced oscillating electric dipole moments
Energy Technology Data Exchange (ETDEWEB)
Hill, Christopher T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2015-06-24
In this study, the axion electromagnetic anomaly induces an oscillating electric dipole for any magnetic dipole. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency m_{a} and strength ~ 10^{-32} e-cm, within four orders of magnitude of the present standard model DC limit, and two orders of magnitude above the nucleon, assuming standard axion model and dark matter parameters. This may suggest sensitive new experimental venues for the axion dark matter search.
Behavioral modeling of Digitally Adjustable Current Amplifier
Directory of Open Access Journals (Sweden)
Josef Polak
2015-03-01
Full Text Available This article presents the digitally adjustable current amplifier (DACA and its analog behavioral model (ABM, which is suitable for both ideal and advanced analyses of the function block using DACA as active element. There are four levels of this model, each being suitable for simulation of a certain degree of electronic circuits design (e.g. filters, oscillators, generators. Each model is presented through a schematic wiring in the simulation program OrCAD, including a description of equations representing specific functions in the given level of the simulation model. The design of individual levels is always verified using PSpice simulations. The ABM model has been developed based on practically measured values of a number of DACA amplifier samples. The simulation results for proposed levels of the ABM model are shown and compared with the results of the real easurements of the active element DACA.
Dynamic dipole-dipole interactions between excitons in quantum dots of different sizes
DEFF Research Database (Denmark)
Matsueda, Hideaki; Leosson, Kristjan; Xu, Zhangcheng;
2004-01-01
A model of the resonance dynamic dipole-dipole interaction between excitons confined in quantum dots (QDs) of different sizes at close enough distance is given in terms of parity inheritance and exchange of virtual photons. Microphotoluminescence spectra of GaAs-AlGaAs coupled QDs are proposed to...
Optical force on toroidal nanostructures: toroidal dipole versus renormalized electric dipole
Zhang, Xu-Lin; Lin, Zhifang; Sun, Hong-Bo; Chan, C T
2015-01-01
We study the optical forces acting on toroidal nanostructures. A great enhancement of optical force is unambiguously identified as originating from the toroidal dipole resonance based on the source-representation, where the distribution of the induced charges and currents is characterized by the three families of electric, magnetic, and toroidal multipoles. On the other hand, the resonant optical force can also be completely attributed to an electric dipole resonance in the alternative field-representation, where the electromagnetic fields in the source-free region are expressed by two sets of electric and magnetic multipole fields based on symmetry. The confusion is resolved by conceptually introducing the irreducible electric dipole, toroidal dipole, and renormalized electric dipole. We demonstrate that the optical force is a powerful tool to identify toroidal response even when its scattering intensity is dwarfed by the conventional electric and magnetic multipoles.
Bubnov, Igor N.; Falkovych, I. S.; Gridin, A. A.; Stanislavsky, A. A.; Reznik, A. P.
2015-01-01
Advantages of the diamond dipole antenna as an active antenna are presented. Such an antenna is like an inverted bow-tie antenna, but the former has some advantages over the ordinary bow-tie antenna. It is shown that the diamond dipole antenna may be an effective element of a new antenna array for low-frequency radio astronomy as well as a communication antenna.
Nara, T.; Koiwa, K.; Takagi, S.; Oyama, D.; Uehara, G.
2014-05-01
This paper presents an algebraic reconstruction method for dipole-quadrupole sources using magnetoencephalography data. Compared to the conventional methods with the equivalent current dipoles source model, our method can more accurately reconstruct two close, oppositely directed sources. Numerical simulations show that two sources on both sides of the longitudinal fissure of cerebrum are stably estimated. The method is verified using a quadrupolar source phantom, which is composed of two isosceles-triangle-coils with parallel bases.
Minimum emittance in storage rings with uniform or nonuniform dipoles
Directory of Open Access Journals (Sweden)
Chun-xi Wang
2009-06-01
Full Text Available A simple treatment of minimum emittance theory in storage rings is presented, favoring vector and matrix forms for a more concise picture. Both conventional uniform dipoles and nonuniform dipoles with bending radius variation are treated. Simple formulas are given for computing the minimum emittance, optimal lattice parameters, as well as effects of nonoptimal parameters. For nonuniform dipoles, analytical results are obtained for a three-piece sandwich dipole model. Minimization of the effective emittance for light sources is given in detail. Usefulness of gradient and/or nonuniform dipoles for reducing the effective emittance is addressed.
三层媒质中电偶极子的仿真%Simulation Analysis of Electric Dipoles in Three-Layer Medium Model
Institute of Scientific and Technical Information of China (English)
宋志宏; 种满东
2016-01-01
The dipole model in sea is the major measures in electromagnetic field, so it is practically important to study the fields in the sea generated by the dipole. In the three layers model of air-sea water-seafloor, the analytical expressions of ELF (extremely low frequency) EM (electromagnetic) wave produced by VED (vertical electric dipole) and HED (horizon⁃tal electric dipole) source located in seawater which had been derived in the space of seawater by using the mirror image theory according to the uniqueness theorem of electromagnetic field. The physical meaning was more apparent, and the de⁃rived formula was more convenient through this method. Simulation results showed that all the components of the HED the field intensity of electric and magnetic fields are greater than the VED. The HED had the directions in the sea deep, but not the VED. These conclusions provided references for the ELF EM wave studies by the HED and VED.%偶极子模型是进行水下电磁场建模的主要手段，研究其在海水中产生的场具有重要的实际意义。针对这个问题，利用镜像法，在空气-海水-海底三层模型下，在电磁场唯一性原理的基础上，通过矢量磁位方法分别推导了垂直和水平电偶极子在海水中产生的极低频电磁波的解析表达式。通过该方法推导电磁波表达式的过程更加简单，且各个分量有明确的物理意义。仿真结果表明：水平电偶极子的电场和磁场的所有分量场强均大于垂直电偶极子的分量；水平电偶极子在海深方向具有方向性，而垂直电偶极子没有方向性。这些有益的结论为进一步利用垂直/水平电偶极子进行极低频电磁波研究提供参考。
Cable Magnetization Effects in the LHC Main Dipole Magnets
Bottura, L; Walckiers, L; Wolf, R
1998-01-01
Several short (1 m) and long (10 m) dipole models have been tested within the scope of the on-going R&D programme for LHC at CERN. We report here the results of measurements of field quality in these dipoles, focussing on the contribution of cable magnetization. We show that the results obtained over a significant (> 10) number of magnets at 1.8 and 4.2 K are in reasonable agreement with calculati ons of the dependence of allowed harmonics on field. The calculations are based on the Bean model of filament magnetization and assume an approximate Jc(B) dependence, calibrated against low field mea surements of strand magnetization. The field quality measurements at low field also correlate satisfactorily to measurements of cable critical current at high field and geometric filament diameter.
Benchmarking an Unstructured-Grid Model for Tsunami Current Modeling
Zhang, Yinglong J.; Priest, George; Allan, Jonathan; Stimely, Laura
2016-12-01
We present model results derived from a tsunami current benchmarking workshop held by the NTHMP (National Tsunami Hazard Mitigation Program) in February 2015. Modeling was undertaken using our own 3D unstructured-grid model that has been previously certified by the NTHMP for tsunami inundation. Results for two benchmark tests are described here, including: (1) vortex structure in the wake of a submerged shoal and (2) impact of tsunami waves on Hilo Harbor in the 2011 Tohoku event. The modeled current velocities are compared with available lab and field data. We demonstrate that the model is able to accurately capture the velocity field in the two benchmark tests; in particular, the 3D model gives a much more accurate wake structure than the 2D model for the first test, with the root-mean-square error and mean bias no more than 2 cm s-1 and 8 mm s-1, respectively, for the modeled velocity.
Terahertz emission by diffusion of carriers and metal-mask dipole inhibition of radiation
Barnes, M E; Daniell, G J; Whitworth, G; Chung, A L; Quarterman, A H; Wilcox, K G; Beere, H E; Ritchie, D A; Apostolopoulos, V
2011-01-01
Terahertz (THz) radiation can be generated by ultrafast photo-excitation of carriers in a semiconductor partly masked by a gold surface. A simulation of the effect taking into account the diffusion of carriers and the electric field shows that the total net current is approximately zero and cannot account for the THz radiation. Finite element modelling and analytic calculations indicate that the THz emission arises because the metal inhibits the radiation from part of the dipole population, thus creating an asymmetry and therefore a net current. Experimental investigations confirm the simulations and show that metal-mask dipole inhibition can be used to create THz emitters.
Chialvo, Ariel A; Moucka, Filip; Vlcek, Lukas; Nezbeda, Ivo
2015-04-16
We developed the Gaussian charge-on-spring (GCOS) version of the original self-consistent field implementation of the Gaussian Charge Polarizable water model and test its accuracy to represent the polarization behavior of the original model involving smeared charges and induced dipole moments. For that purpose we adapted the recently proposed multiple-particle-move (MPM) within the Gibbs and isochoric-isothermal ensembles Monte Carlo methods for the efficient simulation of polarizable fluids. We assessed the accuracy of the GCOS representation by a direct comparison of the resulting vapor-liquid phase envelope, microstructure, and relevant microscopic descriptors of water polarization along the orthobaric curve against the corresponding quantities from the actual GCP water model.
A study of model bivalve siphonal currents
Monismith, Stephen G.; Koseff, Jeffrey R.; Thompson, Janet K.; O'Riordan, Catherine A.; Nepf, Heidi M.
1990-01-01
We carried out experiments studying the hydrodynamics of bivalve siphonal currents in a laboratory flume. Rather than use living animals, we devised a simple, model siphon pair connected to a pump. Fluorescence-based flow visualization was used to characterize siphon-jet flows for several geometric configurations and flow speeds. These measurements show that the boundary-layer velocity profile, siphon height, siphon pair orientation, and size of siphon structure all affect the vertical distribution of the excurrent flow downstream of the siphon pair and the fraction of excurrent that is refiltered. The observed flows may effect both the clearance rate of an entire population of siphonate bivalves as well as the efficiency of feeding of any individual. Our results imply that field conditions are properly represented in laboratory flume studies of phytoplankton biomass losses to benthic bivalves when the shear velocity and bottom roughness are matched to values found in the field. Numerical models of feeding by a bivalve population should include an effective sink distribution which is created by the combined incurrent-excurrent flow field. Near-bed flows need to be accounted for to properly represent these benthic-pelagic exchanges. We also present velocity measurements made with a laser-Doppler anemometer (LDA) for a single configuration (siphons flush with bed, inlet downstream) that show that the siphonal currents have a significant local effect on the properties of a turbulent boundary layer.
Dipole-Dipole Interaction and the Directional Motion of Brownian Motors
Institute of Scientific and Technical Information of China (English)
YU Hui; ZHAO TongJun; JI Qing; SONG YanLi; WANG YongHong; ZHAN Yong
2002-01-01
The electric field of the microtubule is calculated according to its dipole distribution. The conformationalchange of a molecular motor is described by the rotation ofa dipole which interacts with the microtubulc. The mricalsimulation for the particle current shows that this interaction helps to produce a directional motion along the microtubule.And tte average displacement executes step changes that resemble the experimental result for kinesin motors.
Experiments with Dipole Antennas
Kraftmakher, Yaakov
2009-01-01
Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a…
Superconducting high current magnetic Circuit: Design and Parameter Estimation of a Simulation Model
Kiefer, Alexander; Reich, Werner Dr
The Large Hadron Collider (LHC) utilizes superconducting main dipole magnets that bend the trajectory of the particle beams. In order to adjust the not completely homogeneous magnetic feld of the main dipole magnets, amongst others, sextupole correctcorrector magnets are used. In one of the 16 corrector magnet circuits placed in the LHC, 154 of these sextupole corrector magnets (MCS) are connected in series. This circuit extends on a 3.35 km tunnel section of the LHC. In 2015, at one of the 16 circuits a fault was detected. The simulation of this circuit is helpful for fnding the fault by applying alternating current at different frequencies. Within this Thesis a PSpice model for the simulation of the superconducting corrector magnet circuit was designed. The physical properties of the circuit and its elements were analyzed and implemented. For the magnets and bus-bars, sub-circuits were created which reflect the parasitic effects of electrodynamics and electrostats. The inductance values and capacitance valu...
Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods
Watson, Derek W; Ruostekoski, Janne; Fedotov, Vassili A; Zheludev, Nikolay I
2015-01-01
We show how the elusive toroidal dipole moment appears as a radiative excitation eigenmode in a metamolecule resonator that is formed by pairs of plasmonic nanorods. We analyze one such nanorod configuration - a toroidal metamolecule. We find that the radiative interactions in the toroidal metamolecule can be qualitatively represented by a theoretical model based on an electric point dipole arrangement. Both a finite-size rod model and the point dipole approximation demonstrate how the toroidal dipole moment is subradiant and difficult to excite by incident light. By means of breaking the geometric symmetry of the metamolecule, the toroidal mode can be excited by linearly polarized light and we provide simple optimization protocols for maximizing the toroidal dipole mode excitation. This opens up possibilities for simplified control and driving of metamaterial arrays consisting of toroidal dipole unit-cell resonators.
Cox, Robert M.; Sontowski, John; Dougherty, Catherine M.
2005-12-01
This paper describes the evaluation of three diagnostic wind models by direct comparison with wind field data. The models are the California Meteorological Model (CALMET), the Mass Consistent model (MCSCIPUF) associated with the Second Order Closure Integrated Puff (SCIPUFF) transport/dispersion model, and the Stationary Wind Field and Turbulence (SWIFT) model. The evaluation follows previous works by Chang, Franzese & Hanna, who compared the same three models, and by Bradley & Mazzola who evaluated SWIFT coupled with SCIPUFF. As with SWIFT, MCSCIPUF is incorporated in the Hazard Prediction and Assessment Capability (HPAC), while CALMET is linked with the California Puff model (CALPUFF), another transport and dispersion model. The Dipole Pride 26 (DP26) experiments, performed at the US Department of Energy (DOE) Nevada Test Site, are used as the source of the wind data. They provide a comprehensive set of meteorological data with wide-ranging atmospheric stability conditions over a complex terrain. Model calculations were compared with measured data in two phases. The first phase uses complete sets of data from eight locations (the 8M phase) as model inputs, and thus tests the ability of the models to reproduce input conditions. In the second phase, five of the measured wind sites are withheld from input, and instead used for validation of model calculations (the 3M phase). In the first phase, the errors were found (with some exceptions) to be quite small. In the second phase, mean absolute errors were found to be of the order of 1 ms[minus sign]1 and 30°, with only small differences among models in terms of performance.
RECENT TEST RESULTS OF THE FAST-PULSED 4 T COS DIPOLE GSI 001.
Energy Technology Data Exchange (ETDEWEB)
MORITZ, G.; KAUGERTS, J.; ESCALLIER, J.; GANETIS, G.; JAIN, A.; MARONE, A.; MURATORE, J.; THOMAS, R.; WANDERER, P.; ET AL.
2005-05-26
For the FAIR-project at GSI a model dipole was built at BNL with the nominal field of 4 T and a nominal ramp rate of 1 T/S. The magnet design was similar to the RHIC dipole, with some changes for loss reduction and better cooling. The magnet was already successfully tested in a vertical cryostat, with good training behavior. Cryogenic losses were measured and first results of field harmonics were published. However, for a better understanding of the cooling process, quench currents at several ramp rates were investigated. Detailed measurements of the field harmonics at 2 T/S between 0 and 4 T were performed.
Strong CP violation and the neutron electric dipole form factor
Kuckei, J; Faessler, A; Gutsche, T; Kovalenko, S; Lyubovitskij, V E; Pumsa-ard, K; Dib, Claudio; Faessler, Amand; Gutsche, Th.; Kovalenko, Sergey
2005-01-01
We calculate the neutron electric dipole form factor induced by the CP violating theta-term of QCD, within a perturbative chiral quark model which includes pion and kaon clouds. On this basis we derive the neutron electric dipole moment and the electron-neutron Schiff moment. From the existing experimental upper limits on the neutron electric dipole moment we extract constraints on the theta-parameter and compare our results with other approaches.
Yu, Yue; Luo, Zhuxi; Wang, Ziqiang
2014-07-30
We show that the dipole-dipole coupling between Wannier modes in cigar-shaped Bose-Einstein condensates (BECs) is significantly enhanced while the short-range coupling is strongly suppressed. As a result, the dipole-dipole interaction can become the dominant interaction between ultracold alkali Bose atoms. In the long length limit of a cigar-shaped BEC, the resulting effective one-dimensional models possess an effective inverse squared interacting potential, the Calogero-Sutherland potential, which plays a fundamental role in many fields of contemporary physics; but its direct experimental realization has been a challenge for a long time. We propose to realize the Calogero-Sutherland model in ultracold alkali Bose atoms and study the effects of the dipole-dipole interaction.
2004-01-01
The cold mass of a 15-metre main dipole magnet has some fifteen different components. All the main components are manufactured under CERN's direct responsibility. Four of them transit through CERN before being shipped to the dipole assembly contractors, namely the cable, which constitutes the magnet's superconducting core (see Bulletin 14/2004), the beam screens, the heat exchanger tubes and the cold bore beam tubes. The two latter components transit via Building 927 where they undergo part of the production process. The 58-mm diameter heat exchanger tubes will remove heat from the magnets using superfluid helium. The 53-mm diameter cold bore tubes will be placed under vacuum to allow the twin beams to circulate around the LHC.
Maximilien Brice
2004-01-01
The ALICE cavern receives a painting made specially to mark the 50th anniversary of CERN that is mounted on the L3 solenoid magnet, reused from the LEP experiment that ran from 1989 to 2000. The dipole, which is cooled by demineralised water, will bend the path of muons that leave the huge rectangular solenoid. These muons are heavy electrons that interact less with matter allowing them to be studied at large distances from the interaction point.
Dipole strength distribution of {sup 50}Ti
Energy Technology Data Exchange (ETDEWEB)
Gayer, Udo; Beck, Tobias; Beller, Jacob; Mertes, Laura; Pai, Haridas; Pietralla, Norbert; Ries, Philipp; Romig, Christopher; Werner, Volker; Zweidinger, Markus [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany)
2015-07-01
A first nuclear resonance fluorescence (NRF) experiment with a 68% isotopically enriched {sup 50}Ti target has been performed at the superconducting Darmstadt electron linear accelerator S-DALINAC to investigate particle-bound dipole excitations in this nucleus. The target was irradiated with an unpolarized bremsstrahlung photon beam at endpoint energies of 7.5 MeV and 9.7 MeV. The observed excited states are analyzed with respect to their excitation energies, spin quantum numbers and transition strengths. A complementary NRF experiment with polarized photons will be conducted at the High Intensity gamma-ray Source in Durham, NC, USA to determine the polarity of the dipole transitions. Data will be analyzed with regard to the Pygmy Dipole Resonance, a weakly-collective electric dipole excitation which starts to form in nuclei of this mass region. The measured transition strengths will be compared to microscopic calculations in the quasiparticle-phonon model. The investigation of the magnetic dipole strength distribution will focus on strong spin-flip transitions between the p,f spin-orbit partners expected in the nuclear shell model. First results of the measurements and the evaluation will be presented and discussed.
Girwidz, Raimund V.
2016-11-01
The Hertzian dipole is fundamental to the understanding of dipole radiation. It provides basic insights into the genesis of electromagnetic waves and lays the groundwork for an understanding of half-wave antennae and other types. Equations for the electric and magnetic fields of such a dipole can be derived mathematically. However these are very abstract descriptions. Interpreting these equations and understanding travelling electromagnetic waves are highly limited in that sense. Visualizations can be a valuable supplement that vividly present properties of electromagnetic fields and their propagation. The computer simulation presented below provides additional instructive illustrations for university lectures on electrodynamics, broadening the experience well beyond what is possible with abstract equations. This paper refers to a multimedia program for PCs, tablets and smartphones, and introduces and discusses several animated illustrations. Special features of multiple representations and combined illustrations will be used to provide insight into spatial and temporal characteristics of field distributions—which also draw attention to the flow of energy. These visualizations offer additional information, including the relationships between different representations that promote deeper understanding. Finally, some aspects are also illustrated that often remain unclear in lectures.
Yamanaka, Nodoka; Kubota, Takahiro
2013-01-01
The contribution of the R-parity violating supersymmetric model to the fermion electric dipole moment at the two-loop level is analyzed. We show that in general, the Barr-Zee type contribution to the fermion electric dipole moment with the exchange of W and Z bosons is not small compared to the currently known photon exchange one with R-parity violating interactions. We will then give new upper bounds on the imaginary parts of R-parity violating couplings from the experimental data of the electric dipole moments of the electron and of the neutron.
Current approaches to gene regulatory network modelling
Directory of Open Access Journals (Sweden)
Brazma Alvis
2007-09-01
Full Text Available Abstract Many different approaches have been developed to model and simulate gene regulatory networks. We proposed the following categories for gene regulatory network models: network parts lists, network topology models, network control logic models, and dynamic models. Here we will describe some examples for each of these categories. We will study the topology of gene regulatory networks in yeast in more detail, comparing a direct network derived from transcription factor binding data and an indirect network derived from genome-wide expression data in mutants. Regarding the network dynamics we briefly describe discrete and continuous approaches to network modelling, then describe a hybrid model called Finite State Linear Model and demonstrate that some simple network dynamics can be simulated in this model.
Panahi, M.; Solookinejad, G.; Ahmadi Sangachin, E.; Hossein Asadpour, Seyyed
2016-07-01
The impact of the dipole-dipole interaction on the Goo-Hänchen (GH) shifts in reflected and transmitted lights is investigated. A weak probe beam is incident on a cavity containing the donor and acceptor quantum dots embedded in a nonlinear photonic crystal. We deduced that the GH shifts can be easily adjusted via controlling the corresponding parameters of the system in the presence or absence of dipole-dipole interaction. Our proposed model may be useful to developing the all-optical devices based on photonic materials doped with nanoparticles.
Dahlerup-Petersen, K
2001-01-01
Summary form only given, as follows. A long chain of superconducting magnets represents a complex load impedance for the powering and turns into a complex generator during the energy extraction. Detailed information about the circuit is needed for the calculation of a number of parameters and features, which are of vital importance for the choice of powering and extraction equipment and for the prediction of the circuit performance under normal and fault conditions. Constitution of the complex magnet chain impedance is based on a synthesized, electrical model of the basic magnetic elements. This is derived from amplitude and phase measurements of coil and ground impedances from d.c. to 50 kHz and the identification of poles and zeros of the impedance and transfer functions. An electrically compatible RLC model of each magnet type was then synthesized by means of a combination of conventional algorithms. Such models have been elaborated for the final, 15-m long LHC dipole (both apertures in series) as well as ...
T violation in radiative β decay and electric dipole moments
Energy Technology Data Exchange (ETDEWEB)
Dekens, W.; Vos, K.K., E-mail: k.k.vos@rug.nl
2015-12-17
In radiative β decay, T violation can be studied through a spin-independent T-odd correlation. We consider contributions to this correlation by beyond the standard model (BSM) sources of T-violation, arising above the electroweak scale. At the same time such sources, parametrized by dimension-6 operators, can induce electric dipole moments (EDMs). As a consequence, the manifestations of the T-odd BSM physics in radiative β decay and EDMs are not independent. Here we exploit this connection to show that current EDM bounds already strongly constrain the spin-independent T-odd correlation in radiative β decay.
T violation in radiative β decay and electric dipole moments
Directory of Open Access Journals (Sweden)
W. Dekens
2015-12-01
Full Text Available In radiative β decay, T violation can be studied through a spin-independent T-odd correlation. We consider contributions to this correlation by beyond the standard model (BSM sources of T-violation, arising above the electroweak scale. At the same time such sources, parametrized by dimension-6 operators, can induce electric dipole moments (EDMs. As a consequence, the manifestations of the T-odd BSM physics in radiative β decay and EDMs are not independent. Here we exploit this connection to show that current EDM bounds already strongly constrain the spin-independent T-odd correlation in radiative β decay.
T violation in radiative β decay and electric dipole moments
Dekens, W.; Vos, K. K.
2015-12-01
In radiative β decay, T violation can be studied through a spin-independent T-odd correlation. We consider contributions to this correlation by beyond the standard model (BSM) sources of T-violation, arising above the electroweak scale. At the same time such sources, parametrized by dimension-6 operators, can induce electric dipole moments (EDMs). As a consequence, the manifestations of the T-odd BSM physics in radiative β decay and EDMs are not independent. Here we exploit this connection to show that current EDM bounds already strongly constrain the spin-independent T-odd correlation in radiative β decay.
Study the vibration and dynamic response of the dipole girder system for CSNS/RCS
Renhong, Liu; JunSong, Zhang; GuangYuan, Wang
2015-01-01
China Spallation Neutron Source is a high intensity proton accelerator based facility, and its accelerator complex includes two main parts an H- linac and a rapid cycling synchrotron. The RCS accumulates the 80MeV proton beam, and accelerates it to 1.6GeV, with a repetition rate of 25Hz. The dipole of the CSNS RCS is operated at a 25 Hz sinusoidal alternating current which causes severe vibrate. The vibration will influence the long term safety and reliable operation of the magnet. The dipole of the CSNS RCS is an active vibration equipment which is different from the ground vibration accelerator. It is very important to design and study the dynamic characteristics of the dipole girder system. This paper takes the dipole and girder as a specific model system, a method for studying the dynamic characteristics of the system is put forward by combining theoretical calculation with experimental testing. The modal parameters with and without vibration isolator of the dipole girder system are obtain through ANSYS s...
Liu, Shi; Cohen, R. E.
2017-08-01
The role of defects in solids of mixed ionic-covalent bonds such as ferroelectric oxides is complex. Current understanding of defects on ferroelectric properties at the single-defect level remains mostly at the empirical level, and the detailed atomistic mechanisms for many defect-mediated polarization-switching processes have not been convincingly revealed quantum mechanically. We simulate the polarization-electric field (P-E) and strain-electric field (ɛ-E) hysteresis loops for BaTiO3 in the presence of generic defect dipoles with large-scale molecular dynamics and provide a detailed atomistic picture of the defect dipole-enhanced electromechanical coupling. We develop a general first-principles-based atomistic model, enabling a quantitative understanding of the relationship between macroscopic ferroelectric properties and dipolar impurities of different orientations, concentrations, and dipole moments. We find that the collective orientation of dipolar defects relative to the external field is the key microscopic structure feature that strongly affects materials hardening/softening and electromechanical coupling. We show that a small concentration (≈0.1 at. %) of defect dipoles dramatically improves electromechanical responses. This offers the opportunity to improve the performance of inexpensive polycrystalline ferroelectric ceramics through defect dipole engineering for a range of applications including piezoelectric sensors, actuators, and transducers.
Space-charge-controlled field emission model of current conduction through Al2O3 films
Hiraiwa, Atsushi; Matsumura, Daisuke; Kawarada, Hiroshi
2016-02-01
This study proposes a model for current conduction in metal-insulator-semiconductor (MIS) capacitors, assuming the presence of two sheets of charge in the insulator, and derives analytical formulae of field emission (FE) currents under both negative and positive bias. Since it is affected by the space charge in the insulator, this particular FE differs from the conventional FE and is accordingly named the space-charge-controlled (SCC) FE. The gate insulator of this study was a stack of atomic-layer-deposition Al2O3 and underlying chemical SiO2 formed on Si substrates. The current-voltage (I-V) characteristics simulated using the SCC-FE formulae quantitatively reproduced the experimental results obtained by measuring Au- and Al-gated Al2O3/SiO2 MIS capacitors under both biases. The two sheets of charge in the Al2O3 films were estimated to be positive and located at a depth of greater than 4 nm from the Al2O3/SiO2 interface and less than 2 nm from the gate. The density of the former is approximately 1 × 1013 cm-2 in units of electronic charge, regardless of the type of capacitor. The latter forms a sheet of dipoles together with image charges in the gate and hence causes potential jumps of 0.4 V and 1.1 V in the Au- and Al-gated capacitors, respectively. Within a margin of error, this sheet of dipoles is ideally located at the gate/Al2O3 interface and effectively reduces the work function of the gate by the magnitude of the potential jumps mentioned above. These facts indicate that the currents in the Al2O3/SiO2 MIS capacitors are enhanced as compared to those in ideal capacitors and that the currents in the Al-gated capacitors under negative bias (electron emission from the gate) are more markedly enhanced than those in the Au-gated capacitors. The larger number of gate-side dipoles in the Al-gated capacitors is possibly caused by the reaction between the Al and Al2O3, and therefore gate materials that do not react with underlying gate insulators should be chosen
Energy Technology Data Exchange (ETDEWEB)
Alday, Luis F. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands)]. E-mail: l.f.alday@phys.uu.nl; Boer, Jan de [Instituut voor Theoretische Fysica, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)]. E-mail: jdeboer@science.uva.nl; Messamah, Ilies [Instituut voor Theoretische Fysica, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)]. E-mail: imessama@science.uva.nl
2006-07-03
We study gravitational solutions that admit a dual CFT description and carry non-zero dipole charge. We focus on the black ring solution in AdS{sub 3}xS{sup 3} and extract from it the one-point functions of all CFT operators dual to scalar excitations of the six-dimensional metric. In the case of small black rings, characterized by the level N, angular momentum J and dipole charge q{sub 3}, we show how the large N and J dependence of the one-point functions can be reproduced, under certain assumptions, directly from a suitable ensemble in the dual CFT. Finally we present a simple toy model that describes the thermodynamics of the small black ring for arbitrary values of the dipole charge.
Theory of Dipole Induced Electromagnetic Transparency
Puthumpally-Joseph, Raiju; Sukharev, Maxim; Charron, Eric
2015-01-01
A detailed theory describing linear optics of vapors comprised of interacting multi-level quantum emitters is proposed. It is shown both by direct integration of Maxwell-Bloch equations and using a simple analytical model that at large densities narrow transparency windows appear in otherwise completely opaque spectra. The existence of such windows is attributed to overlapping resonances. This effect, first introduced for three-level systems in [R. Puthumpally-Joseph, M. Sukharev, O. Atabek and E. Charron, Phys. Rev. Lett. 113, 163603 (2014)], is due to strongly enhanced dipole-dipole interactions at high emitters' densities. The presented theory extends this effect to the case of multilevel systems. The theory is applied to the D1 transitions of interacting Rb-85 atoms. It is shown that at high atomic densities, Rb-85 atoms can behave as three-level emitters exhibiting all the properties of dipole induced electromagnetic transparency. Applications including slow light and laser pulse shaping are also propose...
Alday, L F; Messamah, I; Alday, Luis F.; Boer, Jan de; Messamah, Ilies
2006-01-01
We study gravitational solutions that admit a dual CFT description and carry non zero dipole charge. We focus on the black ring solution in AdS_3 x S^3 and extract from it the one-point functions of all CFT operators dual to scalar excitations of the six-dimensional metric. In the case of small black rings, characterized by the level N, angular momentum J and dipole charge q_3, we show how the large N and J dependence of the one-point functions can be reproduced, under certain assumptions, directly from a suitable ensemble in the dual CFT. Finally we present a simple toy model that describes the thermodynamics of the small black ring for arbitrary values of the dipole charge.
Cooperative Ordering in Lattices of Interacting Dipoles
Bettles, Robert J; Adams, Charles S
2014-01-01
Using classical electrodynamics simulations we investigate the cooperative behavior of regular monolayers of induced two-level dipoles, including their cooperative decays and shifts. For the particular case of the kagome lattice we observe behavior akin to EIT for lattice spacings less than the probe wavelength. Within this region the dipoles exhibit ferroelectric and anti-ferroelectric ordering. We also model how the cooperative response is manifested in the optical transmission through the kagome lattice, with sharp changes in transmission from 10% to 80% for small changes in lattice spacing.
Complete electric dipole response in 208Pb
Tamii, A; von Neumann-Cosel, P; Fujita, Y; Adachi, T; Bertulani, C A; Carter, J; Dozono, M; Fujita, H; Fujita, K; Hatanaka, K; Heilmann, A M; Ishikawa, D; Itoh, M; Ong, H J; Kawabata, T; Kalmykov, Y; Litvinova, E; Matsubara, H; Nakanishi, K; Neveling, R; Okamura, H; Özel-Tashenov, B; Ponomarev, V Yu; Richter, A; Rubio, B; Sakaguchi, H; Sakemi, Y; Sasamoto, Y; Shimbara, Y; Shimizu, Y; Smit, F D; Suzuki, T; Tameshige, Y; Wambach, J; Yamada, R; Yosoi, M; Zenihiro, J
2011-01-01
A benchmark experiment on 208Pb shows that polarized proton inelastic scattering at very forward angles including 0{\\deg} is a powerful tool for high-resolution studies of electric dipole (E1) and spin magnetic dipole (M1) modes in nuclei over a broad excitation energy range testing up-to-date nuclear model calculations. The E1 polarizability extracted from the data provides a constraint on the neutron skin thickness in 208Pb and the poorly known density dependence of the symmetry energy, relevant to the description of neutron stars.
The neutron electric dipole moment and the Weinberg mechanism
Energy Technology Data Exchange (ETDEWEB)
Chang, D. (Northwestern Univ., Evanston, IL (USA). Dept. of Physics and Astronomy Fermi National Accelerator Lab., Batavia, IL (USA))
1990-01-01
We gave an overview of various mechanism for CP violation paying special attention to their prediction of the neutron electric dipole moment. The implication of the recent developments associated with the color electric dipole moment of gluon in various models of CP-violation are then critically assessed. 25 refs.
Positivity and unitarity constraints on dipole gluon distributions
Peschanski, Robi
2016-01-01
In the high-energy domain, gluon transverse-momentum dependent distributions in nuclei obey constraints coming from positivity and unitarity of the colorless QCD dipole distributions through Fourier-Bessel transformations. Using mathematical properties of Fourier-positive functions, we investigate the nature of these constraints which apply to dipole model building and formulation
Retardation effects in induced atomic dipole-dipole interactions
Graham, S D
2016-01-01
We present mean-field calculations of azimuthally averaged retarded dipole-dipole interactions in a Bose-Einstein condensate induced by a laser, at both long and short wavelengths. Our calculations demonstrate that dipole-dipole interactions become significantly stronger at shorter wavelengths, by as much as 30-fold, due to retardation effects. This enhancement, along with inclusion of the dynamic polarizability, indicate a method of inducing long-range interatomic interactions in neutral atom condensates at significantly lower intensities than previously realized.
Superconducting dipole electromagnet
Purcell, John R.
1977-07-26
A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.
Radiating dipoles in photonic crystals
Busch; Vats; John; Sanders
2000-09-01
The radiation dynamics of a dipole antenna embedded in a photonic crystal are modeled by an initially excited harmonic oscillator coupled to a non-Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the photonic crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra are reproduced. This approach enables direct incorporation of realistic band structure computations into studies of radiative emission from atoms and molecules within photonic crystals. We therefore provide a predictive and interpretative tool for experiments in both the microwave and optical regimes.
Current status: Animal models of nausea
Fox, Robert A.
1991-01-01
The advantages, and possible benefits of a valid, reliable animal model for nausea are discussed, and difficulties inherent to the development of a model are considered. A principle problem for developing models arises because nausea is a subjective sensation that can be identified only in humans. Several putative measures of nausea in animals are considered, with more detailed consideration directed to variation in cardiac rate, levels of vasopressin, and conditioned taste aversion. Demonstration that putative measures are associated with reported nausea in humans is proposed as a requirement for validating measures to be used in animal models. The necessity for a 'real-time' measure of nausea is proposed as an important factor for future research; and the need for improved understanding of the neuroanatomy underlying the emetic syndrome is discussed.
Current status of cosmological MDM model
Mikheeva, E V; Arkhipova, N A; Malinovsky, A M
2000-01-01
An analysis of cosmological models in spatially flat Friedmann Universe with cosmic gravitational wave background and zero $\\Lambda$-term is presented. The number of free parameters is equal to 5, they are $\\sigma_8$, $n$, $\\Omega_\
Surface CUrrents from a Diagnostic model (SCUD): Pacific
National Oceanic and Atmospheric Administration, Department of Commerce — The SCUD data product is an estimate of upper-ocean velocities computed from a diagnostic model (Surface CUrrents from a Diagnostic model). This model makes daily...
Progress on the Development of the $Nb_3Sn$ 11T Dipole for the High Luminosity Upgrade of LHC
Savary, Frederic; Bordini, Bernardo; Bottura, Luca; Fiscarelli, Lucio; Fleiter, Jerome; Foussat, Arnaud; Izquierdo Bermudez, Susana; Karppinen, Mikko; Lackner, Friedrich; Loffler, Christian H; Nilsson, Emelie; Perez, Juan Carlos; Prin, Herve; Principe, Rosario; Ramos, Delio; de Rijk, Gijs; Rossi, Lucio; Smekens, David; Sequeira Tavares, Sandra; Willering, Gerard; Zlobin, Alexander V
2017-01-01
The high-luminosity large hadron collider (LHC) project at CERN entered into the production phase in October 2015 after the completion of the design study phase. In the meantime, the development of the 11 T dipole needed for the upgrade of the collimation system of the machine made significant progress with very good performance of the first two-in-one magnet model of 2-m length made at CERN. The 11 T dipole, which is more powerful than the current main dipoles of LHC, can be made shorter with an equivalent integrated field. This will allow creating space for the installation of additional collimators in specific locations of the dispersion suppressor regions. Following tests carried out during heavy ions runs of LHC in the end of 2015, and a more recent review of the project budget, the installation plan for the 11 T dipole was revised. Consequently, one 11 T dipole full assembly containing two 11 T dipoles of 5.5-m length will be installed on either side of interaction point 7. These two units shall be inst...
Electric dipole moments of charged leptons with sterile fermions
Abada, Asmaa
2016-01-01
We address the impact of sterile fermions on charged lepton electric dipole moments. We show that in order to have a non-vanishing contribution to electric dipole moments, the minimal extension necessitates the addition of at least two sterile fermion states. Sterile neutrinos can give significant contributions to the charged lepton electric dipole moments if the masses of the non-degenerate sterile states are both above the electroweak scale. In addition, the Majorana nature of neutrinos is also important. Furthermore, we apply the computations of the electric dipole moments for the most minimal realisation of the Inverse Seesaw mechanism, in which the Standard Model is extended by two right-handed neutrinos and two sterile fermion states. We show that the two pairs of (heavy) pseudo-Dirac mass eigenstates can give significant contributions to the electron electric dipole moment, lying close to future experimental sensitivity. We further discuss the possibility of beyond the minimal Inverse Seesaw models and...
Confronting Higgcision with Electric Dipole Moments
Cheung, Kingman; Senaha, Eibun; Tseng, Po-Yan
2014-01-01
Current data on the signal strengths and angular spectrum of the 125.5 GeV Higgs boson still allow a CP-mixed state, namely, the pseudoscalar coupling to the top quark can be as sizable as the scalar coupling: $C_u^S \\approx C_u^P =1/2$. CP violation can then arise and manifest in sizable electric dipole moments (EDMs). In the framework of two-Higgs-doublet models, we not only update the Higgs precision (Higgcision) study on the couplings with the most updated Higgs signal strength data, but also compute all the Higgs-mediated contributions from the 125.5 GeV Higgs boson to the EDMs, and confront the allowed parameter space against the existing constraints from the EDM measurements of Thallium, neutron, Mercury, and Thorium monoxide. We found that the combined EDM constraints restrict the pseudoscalar coupling to be less than about $10^{-2}$, unless there are contributions from other Higgs bosons, supersymmetric particles, or other exotic particles that delicately cancel the current Higgs-mediated contributio...
Confronting Higgcision with electric dipole moments
Cheung, Kingman; Lee, Jae Sik; Senaha, Eibun; Tseng, Po-Yan
2014-06-01
Current data on the signal strengths and angular spectrum of the 125.5 GeV Higgs boson still allow a CP-mixed state, namely, the pseudoscalar coupling to the top quark can be as sizable as the scalar coupling: C {/u S } ≈ C {/u P } = 1/2. CP violation can then arise and manifest in sizable electric dipole moments (EDMs). In the framework of two-Higgs-doublet models, we not only update the Higgs precision (Higgcision) study on the couplings with the most updated Higgs signal strength data, but also compute all the Higgs-mediated contributions from the 125.5 GeV Higgs boson to the EDMs, and confront the allowed parameter space against the existing constraints from the EDM measurements of Thallium, neutron, Mercury, and Thorium monoxide. We found that the combined EDM constraints restrict the pseudoscalar coupling to be less than about 10-2, unless there are contributions from other Higgs bosons, supersymmetric particles, or other exotic particles that delicately cancel the current Higgs-mediated contributions.
Diagnostics of the Fermilab Tevatron using an AC dipole
Energy Technology Data Exchange (ETDEWEB)
Miyamoto, Ryoichi [Univ. of Texas, Austin, TX (United States)
2008-08-01
The Fermilab Tevatron is currently the world's highest energy colliding beam facility. Its counter-rotating proton and antiproton beams collide at 2 TeV center-of-mass. Delivery of such intense beam fluxes to experiments has required improved knowledge of the Tevatron's beam optical lattice. An oscillating dipole magnet, referred to as an AC dipole, is one of such a tool to non-destructively assess the optical properties of the synchrotron. We discusses development of an AC dipole system for the Tevatron, a fast-oscillating (f ~ 20 kHz) dipole magnet which can be adiabatically turned on and off to establish sustained coherent oscillations of the beam particles without affecting the transverse emittance. By utilizing an existing magnet and a higher power audio amplifier, the cost of the Tevatron AC dipole system became relatively inexpensive. We discuss corrections which must be applied to the driven oscillation measurements to obtain the proper interpretation of beam optical parameters from AC dipole studies. After successful operations of the Tevatron AC dipole system, AC dipole systems, similar to that in the Tevatron, will be build for the CERN LHC. We present several measurements of linear optical parameters (beta function and phase advance) for the Tevatron, as well as studies of non-linear perturbations from sextupole and octupole elements.
Current Density and Continuity in Discretized Models
Boykin, Timothy B.; Luisier, Mathieu; Klimeck, Gerhard
2010-01-01
Discrete approaches have long been used in numerical modelling of physical systems in both research and teaching. Discrete versions of the Schrodinger equation employing either one or several basis functions per mesh point are often used by senior undergraduates and beginning graduate students in computational physics projects. In studying…
Magnetic dipole moment and keV neutrino dark matter
Energy Technology Data Exchange (ETDEWEB)
Geng, Chao-Qiang, E-mail: geng@phys.nthu.edu.tw [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China); Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan (China); Takahashi, Ryo, E-mail: ryo.takahasi88@gmail.com [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China)
2012-04-04
We study magnetic dipole moments of right-handed neutrinos in a keV neutrino dark matter model. This model is a simple extension of the standard model with only right-handed neutrinos and a pair of charged particles added. One of the right-handed neutrinos is the candidate of dark matter with a keV mass. Some bounds on the dark matter magnetic dipole moment and model parameters are obtained from cosmological observations.
Magnetic dipole moment and keV neutrino dark matter
Geng, Chao-Qiang
2012-01-01
We study magnetic dipole moments of right-handed neutrinos in a keV neutrino dark matter model. This model is a simple extension of the standard model with only right-handed neutrinos and a pair of charged particles added. One of the right-handed neutrinos is the candidate of dark matter with a keV mass. Some bounds on the dark matter magnetic dipole moment and model parameters are obtained from cosmological observations.
Models of Solar Irradiance Variations: Current Status
Indian Academy of Sciences (India)
Natalie A. Krivova; Sami K. Solanki
2008-03-01
Regular monitoring of solar irradiance has been carried out since 1978 to show that solar total and spectral irradiance varies at different time scales. Whereas variations on time scales of minutes to hours are due to solar oscillations and granulation, variations on longer time scales are driven by the evolution of the solar surface magnetic field. Here the most recent advances in modelling of solar irradiance variations on time scales longer than a day are briefly reviewed.
Morimoto, Ryota; Hirata, Akimasa; Laakso, Ilkka; Ziskin, Marvin C.; Foster, Kenneth R.
2017-03-01
This study computes the time constants of the temperature elevations in human head and body models exposed to simulated radiation from dipole antennas, electromagnetic beams, and plane waves. The frequency range considered is from 1 to 30 GHz. The specific absorption rate distributions in the human models are first computed using the finite-difference time-domain method for the electromagnetics. The temperature elevation is then calculated by solving the bioheat transfer equation. The computational results show that the thermal time constants (defined as the time required to reach 63% of the steady state temperature elevation) decrease with the elevation in radiation frequency. For frequencies higher than 4 GHz, the computed thermal time constants are smaller than the averaging time prescribed in the ICNIRP guidelines, but larger than the averaging time in the IEEE standard. Significant differences between the different head models are observed at frequencies higher than 10 GHz, which is attributable to the heat diffusion from the power absorbed in the pinna. The time constants for beam exposures become large with the increase in beam diameter. The thermal time constant in the brain is larger than that in the superficial tissues at high frequencies, because the brain temperature elevation is caused by the heat conduction of energy absorbed in the superficial tissue. The thermal time constant is minimized with an ideal beam with a minimum investigated diameter of 10 mm this minimal time constant is approximately 30 s and is almost independent of the radiation frequency, which is supported by analytic methods. In addition, the relation between the time constant, as defined in this paper, and ‘averaging time’ as it appears in the exposure limits is discussed, especially for short intense pulses. Similar to the laser guidelines, provisions should be included in the limits to limit the fluence for such pulses.
Multinucleon Ejection Model for Two Body Current Neutrino Interactions
Energy Technology Data Exchange (ETDEWEB)
Sobczyk, Jan T.; /Fermilab
2012-06-01
A model is proposed to describe nucleons ejected from a nucleus as a result of two-body-current neutrino interactions. The model can be easily implemented in Monte Carlo neutrino event generators. Various possibilities to measure the two-body-current contribution are discussed. The model can help identify genuine charge current quasielastic events and allow for a better determination of the systematic error on neutrino energy reconstruction in neutrino oscillation experiments.
Backfire antennas with dipole elements
DEFF Research Database (Denmark)
Nielsen, Erik Dragø; Pontoppidan, Knud
1970-01-01
A method is set up for a theoretical investigation of arbitrary backfire antennas based upon dipole structures. The mutual impedance between the dipole elements of the antenna is taken into account, and the field radiated due to a surface wave reflector of finite extent is determined by calculating...
Electric dipole moments of charged leptons at one loop in presence of massive neutrinos
Novales-Sánchez, H; Toscano, J J; Vázquez-Hernández, O
2016-01-01
Violation of $CP$ invariance is a quite relevant phenomenon that is found in the Standard Model, though in small amount. This has been an incentive to look for high-energy descriptions in which $CP$ violation is increased, thus enhancing effects that are suppressed in the Standard Model, such as the electric dipole moments of elementary particles. In the present investigation, we point out that charged currents in which axial couplings are different from vector couplings are able to produce one-loop contributions to electric dipole moments of charged leptons if neutrinos are massive and if these currents violate $CP$. We develop our discussion around charged currents involving heavy neutrinos and a $W'$ gauge boson coupling to Standard Model charged leptons. Using the most stringent bound on the electron electric dipole moment, provided by the ACME Collaboration, we determine that the difference between axial and vector currents lies within $\\sim10^{-10}$ and $\\sim10^{-11}$ for heavy-neutrino masses between $...
Nuclear electric dipole moments for the lowest 1/2+ states in Xe and Ba isotopes
Yoshinaga, N.; Higashiyama, K.; Arai, R.; Teruya, E.
2014-04-01
The electric dipole moments for the lowest 1/2+ states of Xe and Ba isotopes are calculated in terms of the nuclear shell model, which includes two-body nucleon interactions violating parity and time-reversal invariance. Using the wave functions thus obtained, the nuclear electric dipole moments arising from the intrinsic nucleon electric dipole moments and also from asymmetric charge distribution are calculated. The upper limits for the nuclear electric dipole moments of Xe and Ba isotopes are estimated.
Investigation of the Periodic Magnetic Field Modulation in LHC Superconducting Dipoles
Pugnat, P; Siemko, A
2002-01-01
The windings of high-field accelerator magnets are usually made of Rutherford-type superconducting cables. The magnetic field distribution along the axis of such magnets exhibits a periodic modulation with a wavelength equal to the twist pitch length of the cable used in the winding. This effect, resulting from quasi-persistent currents, was investigated with a Hall probes array inserted inside the aperture of the LHC superconducting dipoles, both in short models and full-scale prototypes. The amplitude and the time dependence of this periodic field oscillation have been studied as a function of the magnet current history. The origin and the impact on the LHC dipoles stability of the non-uniform current redistribution producing such a field modulation are discussed.
Sedimentation equilibrium of magnetic nanoparticles with strong dipole-dipole interactions
Kuznetsov, Andrey A.; Pshenichnikov, Alexander F.
2017-03-01
Langevin dynamics simulation is used to study the suspension of interacting magnetic nanoparticles (dipolar spheres) in a zero applied magnetic field and in the presence of a gravitational (centrifugal) field. A particular emphasis is placed on the equilibrium vertical distribution of particles in the infinite horizontal slab. An increase in the dipolar coupling constant λ (the ratio of dipole-dipole interaction energy to thermal energy) from zero to seven units causes an increase in the particle segregation coefficient by several orders of magnitude. The effect of anisotropic dipole-dipole interactions on the concentration profile of particles is the same as that of the isotropic van der Waals attraction modeled by the Lennard-Jones potential. In both cases, the area with a high-density gradient separating the area with high and low particle concentration is formed on the profiles. Qualitative difference between two potentials manifests itself only in the fact that in the absence of a gravitational field the dipole-dipole interactions do not lead to the "gas-liquid" phase transition: no separation of the system into weakly and highly concentrated phases is observed. At high particle concentration and at large values of λ , the orientational ordering of magnetic dipoles takes place in the system. Magnetic structure of the system strongly depends on the imposed boundary conditions. Spontaneous magnetization occurs in the infinite horizontal slab (i.e., in the rectangular cell with two-dimensional periodic boundary conditions). Replacement of the infinite slab by the finite-size hard-wall vertical cylinder leads to the formation of azimuthal (vortex-like) order. The critical values of the coupling constant corresponding to the transition into an ordered state are very close for two geometries.
Coïsson, R
2015-01-01
The interaction between point charge and magnetic dipole is usually considered only for the case of a rigid ferromagnetic dipole (constant-current): here the analysis of force, momentum and energy (including the energy provided by the internal current generator) is generalised to any magnetic dipole behaviour: rigid, paramagnetic, diamagnetic or superconducting (perfectly diamagnetic).
The SMC (Short Model Coil) dipole: An R&D program for Nb3Sn accelerator magnets
Perez, J C; Bordini, B; Canfer, S; Ellwood, G; Feuvrier, J; Guinchard, M; Karppinen, M; Kokkinos, C; Manil, P; Milanese, A; Oberli, L; Regis, F; de Rijk, G
2012-01-01
The Short Model Coil (SMC) assembly has been designed, as test bench for short racetrack coils wound with Nb3Sn cable. The mechanical structure comprises an iron yoke surrounded by a 20 mm thick aluminium alloy shell, and includes four loading pads that transmit the required pre-compression from the outer shell into the two coils. The outer shell is pre-tensioned with mechanical keys that are inserted with the help of pressurized bladders and two 30 mm diameter aluminium alloy rods provide the axial loading to the coil ends. The outer shell, the axial rods, and the coils are instrumented with strain gauges, which allow precise monitoring of the loading conditions during the assembly and at cryogenic temperature during the magnet test. Two SMC assemblies have been completed and cold tested in the frame of a European collaboration between CEA (FR), CERN and STFC (UK) and with the technical support from LBNL (US). This paper describes the main features of the SMC assembly, the experience from the dummy assembli...
The Short Model Coil (SMC) dipole: an R&D program towards Nb3Sn accelerator magnets
Bajko, M; Canfer, S; Ellwood, G; Feuvrier, J; Guinchard, M; Karppinen, M; Kokkinos, C; Manil, P; Milanese, A; Oberli, L; Perez, J-C; Regis, F; de Rijk, G
2011-01-01
The Short Model Coil (SMC) assembly has been designed, as test bench for short racetrack coils wound with Nb3Sn cable. The mechanical structure comprises an iron yoke surrounded by a 20 mm thick aluminium alloy shell, and includes four loading pads that transmit the required pre-compression from the outer shell into the two coils. The outer shell is pre-tensioned with mechanical keys that are inserted with the help of pressurized bladders and two 30 mm diameter aluminium alloy rods provide the axial loading to the coil ends. The outer shell, the axial rods, and the coils are instrumented with strain gauges, which allow precise monitoring of the loading conditions during the assembly and at cryogenic temperature during the magnet test. Two SMC assemblies have been completed and cold tested in the frame of a European collaboration between CEA (FR), CERN and STFC (UK) and with the technical support from LBNL (US). This paper describes the main features of the SMC assembly, the experience from the dummy assemblie...
Current-voltage model of LED light sources
DEFF Research Database (Denmark)
Beczkowski, Szymon; Munk-Nielsen, Stig
2012-01-01
Amplitude modulation is rarely used for dimming light-emitting diodes in polychromatic luminaires due to big color shifts caused by varying magnitude of LED driving current and nonlinear relationship between intensity of a diode and driving current. Current-voltage empirical model of light...
CP-violation and electric dipole moments
Le Dall, Matthias; Ritz, Adam
2013-03-01
Searches for intrinsic electric dipole moments of nucleons, atoms and molecules are precision flavour-diagonal probes of new -odd physics. We review and summarise the effective field theory analysis of the observable EDMs in terms of a general set of CP-odd operators at 1 GeV, and the ensuing model-independent constraints on new physics. We also discuss the implications for supersymmetric models, in light of the mass limits emerging from the LHC.
Magnetic Field of a Dipole and the Dipole-Dipole Interaction
Kraftmakher, Yaakov
2007-01-01
With a data-acquisition system and sensors commercially available, it is easy to determine magnetic fields produced by permanent magnets and to study the dipole-dipole interaction for different separations and angular positions of the magnets. For sufficiently large distances, the results confirm the 1/R[superscript 3] law for the magnetic field…
Modeling the current distribution in HTS tapes with transport current and applied magnetic field
Yazawa, Takashi; Rabbers, Jan-Jaap; Shevchenko, Oleg A.; Haken, ten Bennie; Kate, ten Herman H.J.; Maeda, Hideaki
1999-01-01
A numerical model is developed for the current distribution in a high temperature superconducting (HTS) tape, (Bi,Pb)2Sr2 Ca2Cu3Ox-Ag, subjected to a combination of a transport current and an applied magnetic field. This analysis is based on a two-dimensional formulation of Maxwell's equations in te
Anderson, Vitas
2003-10-21
The aim of this study is to examine the scale and significance of differences in peak specific energy absorption rate (SAR) in the brains of children and adults exposed to radiofrequency emissions from mobile phones. Estimates were obtained by method of multipole analysis of a three layered (scalp/cranium/brain) spherical head exposed to a nearby 0.4 lambda dipole at 900 MHz. A literature review of head parameters that influence SAR induction revealed strong indirect evidence based on total body water content that there are no substantive age-related changes in tissue conductivity after the first year of life. However, it was also found that the thickness of the ear, scalp and cranium do decrease on average with decreasing age, though individual variability within any age group is very high. The model analyses revealed that compared to an average adult, the peak brain 10 g averaged SAR in mean 4, 8, 12 and 16 year olds (yo) is increased by a factor of 1.31, 1.23, 1.15 and 1.07, respectively. However, contrary to the expectations of a recent prominent expert review, the UK Stewart Report, the relatively small scale of these increases does not warrant any special precautionary measures for child mobile phone users since: (a) SAR testing protocols as contained in the CENELEC (2001) standard provide an additional safety margin which ensures that allowable localized SAR limits are not exceeded in the brain; (b) the maximum worst case brain temperature rise (approximately 0.13 to 0.14 degrees C for an average 4 yo) in child users of mobile phones is well within safe levels and normal physiological parameters; and (c) the range of age average increases in children is less than the expected range of variation seen within the adult population.
Cossel, Kevin C; Sinclair, Laura C; Coffey, Tyler; Skripnikov, Leonid V; Petrov, Alexander N; Mosyagin, Nikolai S; Titov, Anatoly V; Field, Robert W; Meyer, Edmund R; Cornell, Eric A; Ye, Jun
2012-01-01
Precision spectroscopy of trapped HfF^+ will be used in a search for the permanent electric dipole moment of the electron (eEDM). While this dipole moment has yet to be observed, various extensions to the standard model of particle physics (such as supersymmetry) predict values that are close to the current limit. We present extensive survey spectroscopy of 19 bands covering nearly 5000 cm^(-1) using both frequency-comb and single-frequency laser velocity-modulation spectroscopy. We obtain high-precision rovibrational constants for eight electronic states including those that will be necessary for state preparation and readout in an actual eEDM experiment.
Quench Performance of the First Twin-aperture 11 T Dipole for LHC upgrades
Zlobin, A V; Apollinari, G; Barzi, E; Chlachidze, G; Nobrega, A; Novitski, I; Stoynev, S; Turrioni, D; Auchmann, B; Izquierdo Bermudez, S; Karppinen, M; Rossi, L; Savary, F; Smekens, D
2015-01-01
FNAL and CERN are developing a twin-aperture 11 T $Nb_{3}Sn$ dipole suitable for installation in the LHC. A single-aperture 2-m long dipole demonstrator and two 1-m long dipole models have been fabricated and tested at FNAL in 2012-2014. The two 1 m long collared coils were then assembled into the first twin-aperture $Nb_{3}Sn$ demonstrator dipole and tested. Test results of this twin-aperture $Nb_{3}Sn$ dipole model are reported and discussed.
2001-01-01
Andrezej Siemko (left), Peter Sievers (centre), and Lucio Rossi (right), have the exciting challenge of preparing and testing 2000 magnets for the LHC. The LHC is going to require a lot of powerful magnets by the time it begins operation in 2006. More specifically, it is going to need 130 special magnets, 400 quadrupoles, and a whopping 1250 dipoles! Preparing and testing these magnets for the conditions they will encounter in the LHC is not an easy task. But evaluation of the most recently received magnet, from the German company Noell, is showing that while the monumental task of receiving and testing nearly 2000 magnets is going to be exhausting, the goals are definitely attainable. At the moment and over the next year, pre-series magnets (the magnets that CERN uses to fine tune performance) are arriving slowly (90 in total will arrive), but by 2003 the rate of series magnet arrival will accelerate to 9 per week, that's over 450 in a single year! And working with these magnets when they arrive is tough. ...
Fractional vortex dipole phase filter
Sharma, Manoj Kumar; Joseph, Joby; Senthilkumaran, Paramasivam
2014-10-01
In spatial filtering experiments, the use of vortex phase filters plays an important role in realizing isotropic edge enhancement. In this paper, we report the use of a vortex dipole phase filter in spatial filtering. A dipole made of fractional vortices is used, and its filtering characteristics are studied. It is observed that the filter performance can be tuned by varying the distance of separation between the vortices of the dipole to achieve better contrast and output noise suppression, and when this distance tends to infinity, the filter performs like a 1-D Hilbert mask. Experimental and simulation results are presented.
Fermion Dipole Moment and Holography
Kulaxizi, Manuela
2015-01-01
In the background of a charged AdS black hole, we consider a Dirac particle endowed with an arbitrary magnetic dipole moment. For non-zero charge and dipole coupling of the bulk fermion, we find that the dual boundary theory can be plagued with superluminal modes. Requiring consistency of the dual CFT amounts to constraining the strength of the dipole coupling by an upper bound. We briefly discuss the implications of our results for the physics of holographic non-Fermi liquids.
Frequency Domain Storage Ring Method for Electric Dipole Moment Measurement
Talman, Richard
2015-01-01
Precise measurement of the electric dipole moments (EDM) of fundamental charged particles would provide a significant probe of physics beyond the standard model. Any measurably large EDM would imply violation of both time reversal and parity conservation, with implications for the matter/anti-matter imbalance of the universe, not currently understood within the standard model. A frequency domain (i.e. difference of frequencies) method is proposed for measuring the EDM of electrons or protons or, with modifications, deuterons. Anticipated precision (i.e. reproducibility) is $10^{-30}\\,$e-cm for the proton EDM, with comparable accuracy (i.e. including systematic error). This would be almost six orders of magnitude smaller than the present upper limit, and will provide a stringent test of the standard model. Resonant polarimetry, made practical by the large polarized beam charge, is the key (most novel, least proven) element of the method. Along with the phase-locked, rolling polarization "Koop spin wheel," reso...
Dipole vortices in the Great Australian Bight
DEFF Research Database (Denmark)
Cresswell, George R.; Lund-Hansen, Lars C.; Nielsen, Morten Holtegaard
2015-01-01
Shipboard measurements from late 2006 made by the Danish Galathea 3 Expedition and satellite sea surface temperature images revealed a chain of cool and warm mushroom' dipole vortices that mixed warm, salty, oxygen-poor waters on and near the continental shelf of the Great Australian Bight (GAB......) with cooler, fresher, oxygen-rich waters offshore. The alternating jets' flowing into the mushrooms were directed mainly northwards and southwards and differed in temperature by only 1.5 degrees C; however, the salinity difference was as much as 0.5, and therefore quite large. The GAB waters were slightly...... denser than the cooler offshore waters. The field of dipoles evolved and distorted, but appeared to drift westwards at 5km day-1 over two weeks, and one new mushroom carried GAB water southwards at 7km day(-1). Other features encountered between Cape Leeuwin and Tasmania included the Leeuwin Current...
Current focusing and steering: modeling, physiology, and psychophysics.
Bonham, Ben H; Litvak, Leonid M
2008-08-01
Current steering and current focusing are stimulation techniques designed to increase the number of distinct perceptual channels available to cochlear implant (CI) users by adjusting currents applied simultaneously to multiple CI electrodes. Previous studies exploring current steering and current focusing stimulation strategies are reviewed, including results of research using computational models, animal neurophysiology, and human psychophysics. Preliminary results of additional neurophysiological and human psychophysical studies are presented that demonstrate the success of current steering strategies in stimulating auditory nerve regions lying between physical CI electrodes, as well as current focusing strategies that excite regions narrower than those stimulated using monopolar configurations. These results are interpreted in the context of perception and speech reception by CI users. Disparities between results of physiological and psychophysical studies are discussed. The differences in stimulation used for physiological and psychophysical studies are hypothesized to contribute to these disparities. Finally, application of current steering and focusing strategies to other types of auditory prostheses is also discussed.
Polarized emission from of an off-centred dipole
Pétri, J
2016-01-01
Radio polarization measurements of pulsed emission from pulsars offer a valuable insight into the basic geometry of the neutron star: inclination angle between the magnetic and rotation axis and inclination of the line of sight. So far, all studies about radio polarization focused on the standard rotating vector model with the underlying assumption of a centred dipole. In this letter, we extend this model to the most general off-centred dipole configuration and give an exact closed analytic expression for the phase-resolved polarization angle. It is shown that contrary to the rotating vector model, for an off-centred dipole, the polarization angle also depends on the emission altitude. Although the fitting parameter space increases from two to six (position of the dipole, altitude and shift of the zero phase), statistical analysis should remain tractable. Observations revealing an evolution of the polarization angle with frequency would undeniably furnish a strong hint for the presence of a decentred magnetic...
Neutron electric dipole moment from gauge/string duality
Bartolini, Lorenzo; Bolognesi, Stefano; Cotrone, Aldo L; Manenti, Andrea
2016-01-01
We compute the electric dipole moment of nucleons in the large $N_c$ QCD model by Witten, Sakai and Sugimoto with $N_f=2$ degenerate massive flavors. Baryons in the model are instantonic solitons of an effective five-dimensional action describing the whole tower of mesonic fields. We find that the dipole electromagnetic form factor of the nucleons, induced by a finite topological $\\theta$ angle, exhibits complete vector meson dominance. We are able to evaluate the contribution of each vector meson to the final result - a small number of modes are relevant to obtain an accurate estimate. Extrapolating the model parameters to real QCD data, the neutron electric dipole moment is evaluated to be $d_n = 1.8 \\cdot 10^{-16}\\, \\theta\\;e\\cdot \\mathrm{cm}$. The electric dipole moment of the proton is exactly the opposite.
Energy Technology Data Exchange (ETDEWEB)
Kaymaz, Z.
1993-12-31
In this dissertation, the authors present the observational results obtained with IMP-8 in the magnetosheath and magnetotail, and compare them with the results from the gas dynamic (GD) and global magnetohydrodynamic (MHD) models. Although the magnetotail has been investigated by many others, the magnetosheath is one of the least studied regions of space despite its importance in solar wind-magnetosphere coupling. In this study, by utilizing a large magnetometer data set obtained simultaneously from IMP-8 and ISEE-3, the authors construct average magnetic field vector maps of the magnetosheath and tail in the cross-sectional plane. They determine how this average structure is influenced by the IMF, the Earth`s dipole tilt angle, and geomagnetic activity. For equatorial IMF`s, the magnetosheath field drapes asymmetrically around the magnetosphere causing a rotation of the field draping pattern, the tail current sheet twists, and plasma sheet field lines cease to show north-south symmetry. The magnetic field structure for north/south IMF`s is also shown to exhibit different properties including irregularities in the sheath (for southward) and placement of the dipolar and flaring regions in the tail. An IMF related perturbation field is observed in the tail which is strongest on the plasma sheet dawn and dusk sides for equatorial IMF, and on the flanks for north-south IMF. The Earth`s dipole tilt with respect to the geomagnetic equator affects the magnetotail current structure by causing its displacement from the geomagnetic equator. The authors examine the structure of the current sheet shape and location extensively using 16-years of IMP-8 magnetic field data. They show how geomagnetic activity affects this displacement. Many other field and current properties of the tail structure are also investigated such as the spatial distribution of the current density vectors and the (J x B) forces.
Automated Design of a Correction Dipole Magnet for LHC
Karppinen, M; Ijspeert, Albert
1996-01-01
A correction dipole magnet, with a horizontal dipole nested inside a vertical dipole has been designed and optimized linking together different electromagnetic software and CAD/CAM systems. The necessary interfaces have recently been established in the program ROXIE which has been developed at CERN for the automatic generation and optimization of superconducting coil geometries. The program provides, in addition to a mathematical optimization chest, interfaces to commercial electromagnetic and structural software packages, CAD/CAM and databases. The results from electromagnetic calculations with different programs have been compared. Some modelling considerations to reduce the computation time are also given.
Image theory for electric dipoles above a conducting anisotropic earth
Mahmoud, S. F.
1984-07-01
New image representations for vertical electric dipoles (VED) above an imperfectly conducting and axially anisotropic earth are developed. These include multidiscrete images at different depths below the air-earth interface and multipole image sources. It is shown that, in contrast with the available image representations in the literature, the developed ones predict the correct behavior of the fields in the far zone along the earth's surface. Extension to a layered earth's model is made. The theory is also extended to the horizontal electric dipole with similar conclusions to the case of the vertical dipole.
Search for electric dipole moments in storage rings
Directory of Open Access Journals (Sweden)
Lenisa Paolo
2016-01-01
Full Text Available The JEDI collaboration aims at making use of storage ring to provide the most precise measurement of the electric dipole moments of hadrons. The method makes exploits a longitudinal polarized beam. The existence an electric dipole moment would generate a torque slowly twisting the particle spin out of plan of the storage ring into the vertical direction. The observation of non zero electric dipole moment would represent a clear sign of new physics beyond the Standard Model. Feasiblity tests are presently undergoing at the COSY storage ring Forschungszentrum Jülich (Germany, to develop the novel techniques to be implemented in a future dedicated storage ring.
Synchronization of interacting quantum dipoles
Zhu, B.; Schachenmayer, J.; Xu, M.; Herrera, F.; Restrepo, J. G.; Holland, M. J.; Rey, A. M.
2015-08-01
Macroscopic ensembles of radiating dipoles are ubiquitous in the physical and natural sciences. In the classical limit the dipoles can be described as damped-driven oscillators, which are able to spontaneously synchronize and collectively lock their phases in the presence of nonlinear coupling. Here we investigate the corresponding phenomenon with arrays of quantized two-level systems coupled via long-range and anisotropic dipolar interactions. Our calculations demonstrate that by incoherently driving dense packed arrays of strongly interacting dipoles, the dipoles can overcome the decoherence induced by quantum fluctuations and inhomogeneous coupling and reach a synchronized steady-state characterized by a macroscopic phase coherence. This steady-state bears much similarity to that observed in classical systems, and yet also exhibits genuine quantum properties such as quantum correlations and quantum phase diffusion (reminiscent of lasing). Our predictions could be relevant for the development of better atomic clocks and a variety of noise tolerant quantum devices.
Quantum optical dipole radiation fields
Stokes, Adam
2016-01-01
We introduce quantum optical dipole radiation fields defined in terms of photon creation and annihilation operators. These fields are identified through their spatial dependence, as the components of the total fields that survive infinitely far from the dipole source. We use these radiation fields to perturbatively evaluate the electromagnetic radiated energy-flux of the excited dipole. Our results indicate that the standard interpretation of a bare atom surrounded by a localised virtual photon cloud, is difficult to sustain, because the radiated energy-flux surviving infinitely far from the source contains virtual contributions. It follows that there is a clear distinction to be made between a radiative photon defined in terms of the radiation fields, and a real photon, whose identification depends on whether or not a given process conserves the free energy. This free energy is represented by the difference between the total dipole-field Hamiltonian and its interaction component.
Current filamentation model for the Weibel/Filamentation instabilities
Ryu, Chang-Mo; Huynh, Cong Tuan; Kim, Chul Min
2016-10-01
A current filamentaion model for a nonrelativistic plasma with e +/e- beam has been presented together with PIC simulations, which can explain the mangetic field enhancement during the Weibel/ Filamentation instabilities. This filament model assumes the Hammer-Rostoker equilibrium. In addition, this model predicts preferential acceleration/deceleration for electron-ion plasmas depending on the injected beam to be e +/e-.
Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model
Akuetevi, C. Q. C.; Wirth, A.
2015-06-01
The dynamics of low latitude turbulent western-boundary currents (WBCs) crossing the Equator are considered using numerical results from integrations of a reduced-gravity shallow-water model. For viscosity values of 1000 m2 s-1 and greater, the boundary layer dynamics compares well to the analytical Munk-layer solution. When the viscosity is reduced, the boundary layer becomes turbulent and coherent structures in the form of anticyclonic eddies, bursts (violent detachments of the viscous sub-layer, VSL) and dipoles appear. Three distinct boundary layers emerge, the VSL, the advective boundary layer and the extended boundary layer. The first is characterized by a dominant vorticity balance between the viscous transport and the advective transport of vorticity; the second by a balance between the advection of planetary vorticity and the advective transport of relative vorticity. The extended boundary layer is the area to which turbulent motion from the boundary extends. The scaling of the three boundary layer thicknesses with viscosity is evaluated. Characteristic scales of the dynamics and dissipation are determined. A pragmatic approach to determine the eddy viscosity diagnostically for coarse-resolution numerical models is proposed.
Dynamics of turbulent western boundary currents at low latitude in a shallow water model
Directory of Open Access Journals (Sweden)
C. Q. C. Akuetevi
2014-11-01
Full Text Available The dynamics of low latitude turbulent western boundary currents crossing the equator is considered using numerical results from integrations of a reduced gravity shallow-water model. For viscosity values of 1000 m2 s−1 and more, the boundary layer dynamics compares well to the analytical Munk-layer solution. When the viscosity is reduced, the boundary layer becomes turbulent and coherent structures in form of anticyclonic eddies, bursts (violent detachments of the viscous sub-layer and dipoles appear. Three distinct boundary layers emerge, the viscous sub-layer, the advective boundary layer and the extended boundary layer. The first is characterized by a dominant vorticity balance between the viscous transport and the advective transport of vorticity. The second by a balance between the advection of planetary vorticity and the advective transport of relative vorticity. The extended boundary layer is the area to which turbulent motion from the boundary extends. The scaling of the three boundary layer thicknesses with viscosity is evaluated. Characteristic scales of the dynamics and dissipation are determined. A pragmatic approach to determine the eddy viscosity diagnostically for coarse resolution numerical models is proposed.
Dynamics of turbulent western boundary currents at low latitude in a shallow water model
Directory of Open Access Journals (Sweden)
C. Q. C. Akuetevi
2014-03-01
Full Text Available The dynamics of low latitude turbulent western boundary currents, subject to two different types of idealized wind forcing, Monsoon Wind and Trade Wind, is considered using numerical results from integrations of a reduced gravity shallow-water model. For viscosity values of 1000 m2 s−1 and above, the boundary layer dynamics compares well to the analytical solutions of the Munk-layer and the inertial-layer, derived from quasigeostrophic theory. Modifications due to variations in the layer thickness (vortex stretching are only important close to the boundary. When the viscosity is reduced the boundary layer becomes turbulent and coherent structures in form of anticyclonic eddies, bursts (violent detachments of the viscous sub-layer and dipoles appear. Three distinct boundary layers emerge, the viscous sub-layer, the advective boundary layer and the extended boundary layer. The first is characterized by a dominant vorticity balance between the viscous transport and the advective transport of vorticity. The second by a balance between the advection of planetary vorticity and the advective transport of relative vorticity. The extended boundary layer is the area to which turbulent motion from the boundary extends. The scaling of the three boundary layer thicknesses with viscosity is evaluated. A pragmatic approach to determine the eddy viscosity diagnostically for coarse resolution numerical models is proposed.
Phenomenology on the QCD dipole picture revisited
Lengyel, A I
2003-01-01
We perform an adjust to the most recent structure function data, considering the QCD dipole picture applied to ep scattering. The structure function F2 at small x and intermediate Q2 can be described by the model containing an economical number of free-parameters, which encodes the hard Pomeron physics. The longitudinal structure function and the gluon distribution are predicted without further adjustments. The data description is effective, whereas a resummed next-to-leading level analysis is deserved.
The vibration research of the AC dipole-girder system for CSNS/RCS
Renhong, Liu; Huamin, Qu; Ling, Kang; Motuo, Wang; Guangyuan, Wang; Haijing, Wang
2013-01-01
China spallation neutron source(CSNS) is a high intensity proton accelerator based facility, and its accelerator complex includes two main parts: an H- linac and a rapid cycling synchrotron(RCS). The rcs accumulates the 80MeV proton beam, and accelerates it to 1.6GeV, with a repetition rate of 25 Hz. The AC dipole of the RCS is operated at a 25Hz sinusoidal alternating current which causes severe vibration. The vibration will influence the long-term safety and reliable operation of the magnet. The dipole magnet of RCS is active vibration equipment which is different with ground vibration accelerator. It is very important to design and research the dynamic characteristic of the dipole-girder system. This paper takes the dipole and girder as a specific model system, a method for researching the dynamic characteristic of the system is put forward by combining theoretical calculation with experimental testing. The ansys simulation method plays a very important role in the girder structure design stage. With the m...
Ding, J; Ding, Jintai; Feigin, Boris
1996-01-01
We construct a commutative current operator $\\bar x^+(z)$ inside $U_q(\\hat{\\frak sl}(2))$. With this operator and the condition of quantum integrability on the quantum current of $U_q(\\hat{\\frak sl}(2))$, we derive the quantization of the semi-infinite construction of integrable modules of The quantization of the functional models for $\\hat{\\frak sl}(2)$ are also given.
Light-induced dipole moment modulation in diarylethenes: a fundamental study.
Bianco, Andrea; Ferrari, Giorgio; Castagna, Rossella; Rossi, Andrea; Carminati, Marco; Pariani, Giorgio; Tommasini, Matteo; Bertarelli, Chiara
2016-11-16
The dipole moment of photochromic diarylethenes is determined in solution for both the coloured and uncoloured forms by measuring the capacitance of a capacitor filled with a photochromic solution as a dielectric material. Diarylethenes with different substituents are investigated and the modulation of the dipole moment is related to their chemical structures. We determine a modulation of the dipole moment up to 4 Debye. We discuss the model used to obtain the dipole moment from the capacitance measurements and we compare the experimental results with the outcomes from DFT calculations. The results highlight the importance of conformational effects in the description of the dipole moment of diarylethenes.
Equatorial Indian Ocean subsurface current variability in an Ocean General Circulation Model
Gnanaseelan, C.; Deshpande, Aditi
2017-05-01
The variability of subsurface currents in the equatorial Indian Ocean is studied using high resolution Ocean General Circulation Model (OGCM) simulations during 1958-2009. February-March eastward equatorial subsurface current (ESC) shows weak variability whereas strong variability is observed in northern summer and fall ESC. An eastward subsurface current with maximum amplitude in the pycnocline is prominent right from summer to winter during strong Indian Ocean Dipole (IOD) years when air-sea coupling is significant. On the other hand during weak IOD years, both the air-sea coupling and the ESC are weak. This strongly suggests the role of ESC on the strength of IOD. The extension of the ESC to the summer months during the strong IOD years strengthens the oceanic response and supports intensification and maintenance of IODs through modulation of air sea coupling. Although the ESC is triggered by equatorial winds, the coupled air-sea interaction associated with IODs strengthens the ESC to persist for several seasons thereby establishing a positive feedback cycle with the surface. This suggests that the ESC plays a significant role in the coupled processes associated with the evolution and intensification of IOD events by cooling the eastern basin and strengthening thermocline-SST (sea surface temperature) interaction. As the impact of IOD events on Indian summer monsoon is significant only during strong IOD years, understanding and monitoring the evolution of ESC during these years is important for summer monsoon forecasting purposes. There is a westward phase propagation of anomalous subsurface currents which persists for a year during strong IOD years, whereas such persistence or phase propagation is not seen during weak IOD years, supporting the close association between ESC and strength of air sea coupling during strong IOD years. In this study we report the processes which strengthen the IOD events and the air sea coupling associated with IOD. It also unravels
Modelling of the ring current in Saturn's magnetosphere
Giampieri, G.; Dougherty, M.
2004-02-01
. The existence of a ring current inside Saturn's magnetosphere was first suggested by smith80 and ness81,ness82, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. connerney83 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set. First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects.
Zhang, Wen-Zhuo
2012-01-01
We derive a set of optical Bloch equations (OBEs) directly from the minimal-coupling Hamiltonian density of the bound-state quantum electrodynamics (bound-state QED). Such optical Bloch equations are beyond the former widely-used ones due to that there is no electric dipole approximation (EDA) on the minimal-coupling Hamiltonian density of the bound-state QED. Then our optical Bloch equations can describe a two-level atom interacting with a monochromatic light of arbitrary wavelength, which are suitable to study the spectroscopy and the Rabi oscillations of two-level atoms in X-ray laser beams since that the wavelength of X-ray is close to an atom to make the electric dipole approximation (EDA) invalid.
Effects of gastrointestinal tissue structure on computed dipole vectors
Austin, Travis M; Li, Liren; Pullan, Andrew J; Cheng, Leo K
2007-01-01
Background Digestive diseases are difficult to assess without using invasive measurements. Non-invasive measurements of body surface electrical and magnetic activity resulting from underlying gastro-intestinal activity are not widely used, in large due to their difficulty in interpretation. Mathematical modelling of the underlying processes may help provide additional information. When modelling myoelectrical activity, it is common for the electrical field to be represented by equivalent dipole sources. The gastrointestinal system is comprised of alternating layers of smooth muscle (SM) cells and Interstitial Cells of Cajal (ICC). In addition the small intestine has regions of high curvature as the intestine bends back upon itself. To eventually use modelling diagnostically, we must improve our understanding of the effect that intestinal structure has on dipole vector behaviour. Methods Normal intestine electrical behaviour was simulated on simple geometries using a monodomain formulation. The myoelectrical fields were then represented by their dipole vectors and an examination on the effect of structure was undertaken. The 3D intestine model was compared to a more computationally efficient 1D representation to determine the differences on the resultant dipole vectors. In addition, the conductivity values and the thickness of the different muscle layers were varied in the 3D model and the effects on the dipole vectors were investigated. Results The dipole vector orientations were largely affected by the curvature and by a transmural gradient in the electrical wavefront caused by the different properties of the SM and ICC layers. This gradient caused the dipoles to be oriented at an angle to the principal direction of electrical propagation. This angle increased when the ratio of the longitudinal and circular muscle was increased or when the the conductivity along and across the layers was increased. The 1D model was able to represent the geometry of the small
Effects of gastrointestinal tissue structure on computed dipole vectors
Directory of Open Access Journals (Sweden)
Pullan Andrew J
2007-10-01
Full Text Available Abstract Background Digestive diseases are difficult to assess without using invasive measurements. Non-invasive measurements of body surface electrical and magnetic activity resulting from underlying gastro-intestinal activity are not widely used, in large due to their difficulty in interpretation. Mathematical modelling of the underlying processes may help provide additional information. When modelling myoelectrical activity, it is common for the electrical field to be represented by equivalent dipole sources. The gastrointestinal system is comprised of alternating layers of smooth muscle (SM cells and Interstitial Cells of Cajal (ICC. In addition the small intestine has regions of high curvature as the intestine bends back upon itself. To eventually use modelling diagnostically, we must improve our understanding of the effect that intestinal structure has on dipole vector behaviour. Methods Normal intestine electrical behaviour was simulated on simple geometries using a monodomain formulation. The myoelectrical fields were then represented by their dipole vectors and an examination on the effect of structure was undertaken. The 3D intestine model was compared to a more computationally efficient 1D representation to determine the differences on the resultant dipole vectors. In addition, the conductivity values and the thickness of the different muscle layers were varied in the 3D model and the effects on the dipole vectors were investigated. Results The dipole vector orientations were largely affected by the curvature and by a transmural gradient in the electrical wavefront caused by the different properties of the SM and ICC layers. This gradient caused the dipoles to be oriented at an angle to the principal direction of electrical propagation. This angle increased when the ratio of the longitudinal and circular muscle was increased or when the the conductivity along and across the layers was increased. The 1D model was able to represent the
Pygmy dipole resonance in 208Pb
Poltoratska, I; Tamii, A; Adachi, T; Bertulani, C A; Carter, J; Dozono, M; Fujita, H; Fujita, K; Fujita, Y; Hatanaka, K; Itoh, M; Kawabata, T; Kalmykov, Y; Krumbholz, A M; Litvinova, E; Matsubara, H; Nakanishi, K; Neveling, R; Okamura, H; Ong, H J; Özel-Tashenov, B; Ponomarev, V Yu; Richter, A; Rubio, B; Sakaguchi, H; Sakemi, Y; Sasamoto, Y; Shimbara, Y; Shimizu, Y; Smit, F D; Suzuki, T; Tameshige, Y; Wambach, J; Yosoi, M; Zenihiro, J
2012-01-01
Scattering of protons of several hundred MeV is a promising new spectroscopic tool for the study of electric dipole strength in nuclei. A case study of 208Pb shows that at very forward angles J^pi = 1- states are strongly populated via Coulomb excitation. A separation from nuclear excitation of other modes is achieved by a multipole decomposition analysis of the experimental cross sections based on theoretical angular distributions calculated within the quasiparticle-phonon model. The B(E1) transition strength distribution is extracted for excitation energies up to 9 MeV, i.e., in the region of the so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows sensitivity to the underlying structure of the E1 transitions, which allows for the first time an experimental extraction of the strength and energy centroid of the PDR.
Magnetic Dipole Band in 113^In
Institute of Scientific and Technical Information of China (English)
马克岩; 杨东; 陆景彬; 王烈林; 王辉东; 刘运祚; 刘弓冶; 李黎; 马英君; 杨森; 李广生; 贺创业; 李雪琴
2012-01-01
High spin states in the odd-A nucleus 113^In have been investigated using the re- action 110^Pd（7^Li, 4n） at a beam energy of 50 MeV. A new positive parity dipole band with the configuration of π（g9/2）^-lv（h11/2）^2 v （g7/2）^2 is established. The effective interaction V（θ） values of this band have been successfully described by a semiclassical geometric model based on shear mechanism, which show that the dipole band has the characteristics of magnetic rotation. In addition the collective rotational angular momentum for this band is extracted. The results show that the core contribution increases gradually with the increase of the rotation frequency.
Theoretical study of the alkaline-earth (LiBe)+ ion: structure, spectroscopy and dipole moments
Ghanmi, C.; Farjallah, M.; Berriche, H.
2017-03-01
We study theoretically the structure and spectroscopic properties of the alkali alkaline-earth (LiBe)+ ion. The potential energy curves and their spectroscopic parameters, permanent and transition dipole moments are determined with a quantum chemistry approach. The (LiBe)+ ion is modelled as two valence electron system moving in the field of Be2+ and Li+ cores, which are described by pseudopotentials. In addition, effective core-polarization potentials are included to correct the energy. The molecular calculations are performed using a standard quantum chemistry approach based on the pseudopotential model, Gaussian basis sets, effective core polarization potentials, and full configuration interaction (CI) calculations. The precision of our spectroscopic parameters are discussed by comparison with currently available theoretical results. A rather good agreement is observed for the ground and first excited states. The permanent dipole moments reveal many abrupt changes, which are localized at particular distances corresponding to the positions of the avoided crossings.
Inter-model analysis of tsunami-induced coastal currents
Lynett, Patrick J.; Gately, Kara; Wilson, Rick; Montoya, Luis; Arcas, Diego; Aytore, Betul; Bai, Yefei; Bricker, Jeremy D.; Castro, Manuel J.; Cheung, Kwok Fai; David, C. Gabriel; Dogan, Gozde Guney; Escalante, Cipriano; González-Vida, José Manuel; Grilli, Stephan T.; Heitmann, Troy W.; Horrillo, Juan; Kânoğlu, Utku; Kian, Rozita; Kirby, James T.; Li, Wenwen; Macías, Jorge; Nicolsky, Dmitry J.; Ortega, Sergio; Pampell-Manis, Alyssa; Park, Yong Sung; Roeber, Volker; Sharghivand, Naeimeh; Shelby, Michael; Shi, Fengyan; Tehranirad, Babak; Tolkova, Elena; Thio, Hong Kie; Velioğlu, Deniz; Yalçıner, Ahmet Cevdet; Yamazaki, Yoshiki; Zaytsev, Andrey; Zhang, Y. J.
2017-06-01
To help produce accurate and consistent maritime hazard products, the National Tsunami Hazard Mitigation Program organized a benchmarking workshop to evaluate the numerical modeling of tsunami currents. Thirteen teams of international researchers, using a set of tsunami models currently utilized for hazard mitigation studies, presented results for a series of benchmarking problems; these results are summarized in this paper. Comparisons focus on physical situations where the currents are shear and separation driven, and are thus de-coupled from the incident tsunami waveform. In general, we find that models of increasing physical complexity provide better accuracy, and that low-order three-dimensional models are superior to high-order two-dimensional models. Inside separation zones and in areas strongly affected by eddies, the magnitude of both model-data errors and inter-model differences can be the same as the magnitude of the mean flow. Thus, we make arguments for the need of an ensemble modeling approach for areas affected by large-scale turbulent eddies, where deterministic simulation may be misleading. As a result of the analyses presented herein, we expect that tsunami modelers now have a better awareness of their ability to accurately capture the physics of tsunami currents, and therefore a better understanding of how to use these simulation tools for hazard assessment and mitigation efforts.
Formation number for vortex dipoles
Sadri, Vahid; Krueger, Paul S.
2016-11-01
This investigation considers the axisymmetric formation of two opposite sign concentric vortex rings from jet ejection between concentric cylinders. This arrangement is similar to planar flow in that the vortex rings will travel together when the gap between the cylinders is small, similar to a vortex dipole, but it has the advantage that the vortex motion is less constrained than the planar case (vortex stretching and vortex line curvature is allowed). The flow was simulated numerically at a jet Reynolds number of 1,000 (based on ΔR and the jet velocity), jet pulse length-to-gap ratio (L / ΔR) in the range 10-20, and gap-to-outer radius ratio (ΔR /Ro) in the range 0.01-0.1. Small gap ratios were chosen for comparison with 2D results. In contrast with 2D results, the closely paired vortices in this study exhibited pinch-off from the generating flow and finite formation numbers. The more complex flow evolution afforded by the axisymmetric model and its influence on the pinch-off process will be discussed. This material is based on work supported by the National Science Foundation under Grant No. 1133876 and SMU. This supports are gratefully acknowledged.
Angle-dependent quantum Otto heat engine based on coherent dipole-dipole coupling
Su, Shan-He; Luo, Xiao-Qing; Chen, Jin-Can; Sun, Chang-Pu
2016-08-01
Electromagnetic interactions between molecules or within a molecule have been widely observed in biological systems and exhibit broad application for molecular structural studies. Quantum delocalization of molecular dipole moments has inspired researchers to explore new avenues to utilize this physical effect for energy harvesting devices. Herein, we propose a simple model of the angle-dependent quantum Otto heat engine which seeks to facilitate the conversion of heat to work. Unlike previous studies, the adiabatic processes are accomplished by varying only the directions of the magnetic field. We show that the heat engine continues to generate power when the angle relative to the vector r joining the centres of coupled dipoles departs from the magic angle θm where the static coupling vanishes. A significant improvement in the device performance has to be attributed to the presence of the quantum delocalized levels associated with the coherent dipole-dipole coupling. These results obtained may provide a promising model for the biomimetic design and fabrication of quantum energy generators.
Modelling of helical current filaments induced by LHW on EAST
Energy Technology Data Exchange (ETDEWEB)
Rack, Michael; Denner, Peter; Liang, Yunfeng [Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, D-52425 Juelich (Germany); Zeng, Long [Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, D-52425 Juelich (Germany); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Gong, Xianzu; Gan, Kaifu; Wang, Liang; Liu, Fukun; Qian, Jinping; Shen, Biao; Li, Jiangang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Gauthier, Eric [Association EURATOM-CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Collaboration: the EAST Team
2013-07-01
Helical radiation belts have been observed in the scrape-off layer (SOL) of the plasma during the application of lower hybrid wave (LHW) heating at the superconducting tokamak EAST. Modelled SOL field lines, starting in-front of the LHW antennas, show agreement in position and pitch angle to the experimental observed radiation belts. A splitting of the strike-line can be observed on the outer divertor plates during the application of LHW heating. Agreement in the comparison of the Mirnov coil signals and a modelled electric current flow along these SOL field lines was found. A lower hybrid current drive can induce such an electric current flow near the plasma edge. This electric current flow causes a change of the plasma topology which could result in the splitting of the strike-line as known from the application of resonant magnetic perturbation fields. Comparisons of modelled footprint structures and experimental observed heat load patterns in the divertor region are discussed.
An Improved Search for the Neutron Electric Dipole Moment
Burghoff, M; Ban, G; Lefort, T; Lemiere, Y; Naviliat-Cuncic, O; Pierre, E; Quemener, G; Zejma, J; Kasprzak, M; Knowles, P; Weis, A; Pignol, G; Rebreyend, D; Afach, S; Bison, G; Becker, J; Severijns, N; Roccia, S; Plonka-Spehr, C; Zennerz, J; Heil, W; Koch, H C; Kraft, A; Lauer, T; Sobolev, Yu; Chowdhuri, Z; Krempel, J; Lauss, B; Mtchedlishvili, A; Schmidt-Wellenburg, P; Zsigmond, G; Fertl, M; Franke, B; Horras, M; Kirch, K; Piegsa, F
2011-01-01
A permanent electric dipole moment of fundamental spin-1/2 particles violates both parity (P) and time re- versal (T) symmetry, and hence, also charge-parity (CP) symmetry since there is no sign of CPT-violation. The search for a neutron electric dipole moment (nEDM) probes CP violation within and beyond the Stan- dard Model. The experiment, set up at the Paul Scherrer Institute (PSI), an improved, upgraded version of the apparatus which provided the current best experimental limit, dn < 2.9E-26 ecm (90% C.L.), by the RAL/Sussex/ILL collaboration: Baker et al., Phys. Rev. Lett. 97, 131801 (2006). In the next two years we aim to improve the sensitivity of the apparatus to sigma(dn) = 2.6E-27 ecm corresponding to an upper limit of dn < 5E-27 ecm (95% C.L.), in case for a null result. In parallel the collaboration works on the design of a new apparatus to further increase the sensitivity to sigma(dn) = 2.6E-28 ecm.
Merging imagery and models for river current prediction
Blain, Cheryl Ann; Linzell, Robert S.; McKay, Paul
2011-06-01
To meet the challenge of operating in river environments with denied access and to improve the riverine intelligence available to the warfighter, advanced high resolution river circulation models are combined with remote sensing feature extraction algorithms to produce a predictive capability for currents and water levels in rivers where a priori knowledge of the river environment is limited. A River Simulation Tool (RST) is developed to facilitate the rapid configuration of a river model. River geometry is extracted from the automated processing of available imagery while minimal user input is collected to complete the parameter and forcing specifications necessary to configure a river model. Contingencies within the RST accommodate missing data such as a lack of water depth information and allow for ensemble computations. Successful application of the RST to river environments is demonstrated for the Snohomish River, WA. Modeled currents compare favorably to in-situ currents reinforcing the value of the developed approach.
A Neuron Model Based Ultralow Current Sensor System for Bioapplications
Directory of Open Access Journals (Sweden)
A. K. M. Arifuzzman
2016-01-01
Full Text Available An ultralow current sensor system based on the Izhikevich neuron model is presented in this paper. The Izhikevich neuron model has been used for its superior computational efficiency and greater biological plausibility over other well-known neuron spiking models. Of the many biological neuron spiking features, regular spiking, chattering, and neostriatal spiny projection spiking have been reproduced by adjusting the parameters associated with the model at hand. This paper also presents a modified interpretation of the regular spiking feature in which the firing pattern is similar to that of the regular spiking but with improved dynamic range offering. The sensor current ranges between 2 pA and 8 nA and exhibits linearity in the range of 0.9665 to 0.9989 for different spiking features. The efficacy of the sensor system in detecting low amount of current along with its high linearity attribute makes it very suitable for biomedical applications.
MODEL STUDY OF THE DOUBLE FED MACHINE WITH CURRENT CONTROL
Directory of Open Access Journals (Sweden)
A. S. Lyapin
2016-07-01
Full Text Available The paper deals with modeling results of the double fed induction machine with current control in the rotor circuit. We show the most promising applications of electric drives on the basis of the double fed induction machine and their advantages. We present and consider functional scheme of the electric drive on the basis of the double fed induction machine with current control. Equations are obtained for creation of such machine mathematical model. Expressions for vector projections of rotor current are given. According to the obtained results, the change of the vector projections of rotor current ensures operation of the double fed induction machine with the specified values of active and reactive stator power throughout the variation range of sliding motion. We consider static characteristics of double fed machine with current control. Energy processes proceeding in the machine are analyzed. We confirm the operationpossibility of double fed induction machine with current controlin the rotor circuit with given values of active and reactive stator power. The presented results can be used for creation of mathematical models and static characteristics of double fed machines with current control of various capacities.
Flavour-changing neutral currents in models with extra ' boson
Indian Academy of Sciences (India)
S Sahoo; L Maharana
2004-09-01
New neutral gauge bosons ' are the features of many models addressing the physics beyond the standard model. Together with the existence of new neutral gauge bosons, models based on extended gauge groups (rank > 4) often predict new charged fermions also. A mixing of the known fermions with new states, with exotic weak-isospin assignments (left-handed singlets and right-handed doublets) will induce tree-level flavour-changing neutral interactions mediated by exchange, while if the mixing is only with new states with ordinary weak-isospin assignments, the flavour-changing neutral currents are mainly due to the exchange of the new neutral gauge boson '. We review flavour-changing neutral currents in models with extra ' boson. Then we discuss some flavour-changing processes forbidden in the standard model and new contributions to standard model processes.
Dipole modes with depressed amplitudes in red giants are mixed modes
Mosser, B; Pincon, C; Takata, M; Vrard, M; Barban, C; Goupil, M-J; Kallinger, T; Samadi, R
2016-01-01
Seismic observations have shown that a number of evolved stars exhibit low-amplitude dipole modes, which are referred to as depressed modes. Recently, these low amplitudes have been attributed to the presence of a strong magnetic field in the stellar core of those stars. We intend to study the properties of depressed modes in evolved stars, which is a necessary condition before concluding on the physical nature of the mechanism responsible for the reduction of the dipole mode amplitudes. We perform a thorough characterization of the global seismic parameters of depressed dipole modes and show that these modes have a mixed character. The observation of stars showing dipole mixed modes that are depressed is especially useful for deriving model-independent conclusions on the dipole mode damping. Observations prove that depressed dipole modes in red giants are not pure pressure modes but mixed modes. This result invalidates the hypothesis that the depressed dipole modes result from the suppression of the oscillat...
Coherent manipulation of two dipole-dipole interacting ions
Beige, A; Knight, P L; Plenio, M B; Thompson, R C
2000-01-01
We investigate to what extent two trapped ions can be manipulated coherently when their coupling is mediated by a dipole-dipole interaction. We will show how the resulting level shift induced by this interaction can be used to create entanglement, while the decay of the states remains nearly negligible. This will allow us to implement conditional dynamics (a CNOT gate) and single qubit operations. We propose two different experimental realisations where a large level shift can be achieved and discuss both the strengths and weaknesses of this scheme from the point of view of a practical realization.
Tunable Entanglement, Antibunching and Saturation effects in Dipole Blockade
Gillet, J; Bastin, T
2009-01-01
We report a simple model which enables us to analyze quantitatively the dipole blockade effect on the dynamical evolution of a two two-level atom system driven by an external laser field. The multiple excitations of the atomic sample are taken into account. We find very large concurrence in the dipole blockade regime. We further find that entanglement can be tuned by changing the intensity of the exciting laser. We also report a way to lift the dipole blockade paving the way to manipulate in a controllable way the blockade effects. We finally report how a continuous monitoring of the dipole blockade is possible using photon-photon correlations of the scattered light.
Modeling the Inner Magnetosphere: Radiation Belts, Ring Current, and Composition
Glocer, Alex
2011-01-01
The space environment is a complex system defined by regions of differing length scales, characteristic energies, and physical processes. It is often difficult, or impossible, to treat all aspects of the space environment relative to a particular problem with a single model. In our studies, we utilize several models working in tandem to examine this highly interconnected system. The methodology and results will be presented for three focused topics: 1) Rapid radiation belt electron enhancements, 2) Ring current study of Energetic Neutral Atoms (ENAs), Dst, and plasma composition, and 3) Examination of the outflow of ionospheric ions. In the first study, we use a coupled MHD magnetosphere - kinetic radiation belt model to explain recent Akebono/RDM observations of greater than 2.5 MeV radiation belt electron enhancements occurring on timescales of less than a few hours. In the second study, we present initial results of a ring current study using a newly coupled kinetic ring current model with an MHD magnetosphere model. Results of a dst study for four geomagnetic events are shown. Moreover, direct comparison with TWINS ENA images are used to infer the role that composition plays in the ring current. In the final study, we directly model the transport of plasma from the ionosphere to the magnetosphere. We especially focus on the role of photoelectrons and and wave-particle interactions. The modeling methodology for each of these studies will be detailed along with the results.
Neural Network based Modeling and Simulation of Transformer Inrush Current
Directory of Open Access Journals (Sweden)
Puneet Kumar Singh
2012-05-01
Full Text Available Inrush current is a very important phenomenon which occurs during energization of transformer at no load due to temporary over fluxing. It depends on several factors like magnetization curve, resistant and inductance of primary winding, supply frequency, switching angle of circuit breaker etc. Magnetizing characteristics of core represents nonlinearity which requires improved nonlinearity solving technique to know the practical behavior of inrush current. Since several techniques still working on modeling of transformer inrush current but neural network ensures exact modeling with experimental data. Therefore, the objective of this study was to develop an Artificial Neural Network (ANN model based on data of switching angle and remanent flux for predicting peak of inrush current. Back Propagation with Levenberg-Marquardt (LM algorithm was used to train the ANN architecture and same was tested for the various data sets. This research work demonstrates that the developed ANN model exhibits good performance in prediction of inrush current’s peak with an average of percentage error of -0.00168 and for modeling of inrush current with an average of percentage error of -0.52913.
Bent Solenoids with Superimposed Dipole Fields
Energy Technology Data Exchange (ETDEWEB)
Meinke, Rainer, B.; Goodzeit, Carl, L.
2000-03-21
A conceptual design and manufacturing technique were developed for a superconducting bent solenoid magnet with a superimposed dipole field that would be used as a dispersion device in the cooling channel of a future Muon Collider. The considered bent solenoid is equivalent to a 180° section of a toroid with a major radius of ~610 mm and a coil aperture of ~416 mm. The required field components of this magnet are 4 tesla for the solenoid field and 1 tesla for the superimposed dipole field. A magnet of this size and shape, operating at these field levels, has to sustain large Lorentz forces resulting in a maximum magnetic pressure of about 2,000 psi. A flexible round mini-cable with 37 strands of Cu-NbTi was selected as the superconductor. Detailed magnetic analysis showed that it is possible to obtain the required superimposed dipole field by tilting the winding planes of the solenoid by ~25°. A complete structural analysis of the coil support system and the helium containment vessel under thermal, pressure, and Lorentz force loads was carried out using 3D finite element models of the structures. The main technical issues were studied and solutions were worked out so that a highly reliable magnet of this type can be produced at an affordable cost.
Meson Exchange Current (MEC) Models in Neutrino Interaction Generators
Katori, Teppei
2013-01-01
Understanding of the so-called 2 particle-2 hole (2p-2h) effect is an urgent program in neutrino interaction physics for current and future oscillation experiments. Such processes are believed to be responsible for the event excesses observed by recent neutrino experiments. The 2p-2h effect is dominated by the meson exchange current (MEC), and is accompanied by a 2-nucleon emission from the primary vertex, instead of a single nucleon emission from the charged-current quasi-elastic (CCQE) interaction. Current and future high resolution experiments can potentially nail down this effect. For this reason, there are world wide efforts to model and implement this process in neutrino interaction simulations. In these proceedings, I would like to describe how this channel is modeled in neutrino interaction generators.
Preferential Rotation of Chiral Dipoles in Isotropic Turbulence
Kramel, Stefan; Voth, Greg A.; Tympel, Saskia; Toschi, Federico
2016-10-01
We introduce a new particle shape which shows preferential rotation in three dimensional homogeneous isotropic turbulence. We call these particles chiral dipoles because they consist of a rod with two helices of opposite handedness, one at each end. 3D printing is used to fabricate these particles with a length in the inertial range and their rotations are tracked in a turbulent flow between oscillating grids. High aspect ratio chiral dipoles preferentially align with their long axis along the extensional eigenvectors of the strain rate tensor, and the helical ends respond to the extensional strain rate with a mean spinning rate that is nonzero. We use Stokesian dynamics simulations of chiral dipoles in pure strain flow to quantify the dependence of spinning on particle shape. Based on the known response to pure strain, we build a model that gives the spinning rate of small chiral dipoles using velocity gradients along Lagrangian trajectories from high resolution direct numerical simulations. The statistics of chiral dipole spinning determined with this model show surprisingly good agreement with the measured spinning of much larger chiral dipoles in the experiments.
1974-01-01
Stacks of SPS Dipole Magnets ready for installation in the tunnel. The SPS uses a separated function lattice with dipoles for bending and quadrupoles for focusing. The 6.2 m long normal conducting dipoles are of H-type with coils that are bent-up at the ends. There are two types, B1 (total of 360) and B2 (384). Both are for a maximum field of 1.8 Tesla and have the same outer dimensions (450x800 mm2 vxh) but with different gaps (B1: 39x129 mm2, B2: 52x92 mm2) tailored to the beam size. The yoke, made of 1.5 mm thick laminations, consists of an upper and a lower half joined together in the median plane once the coils have been inserted.
Synchronization of Interacting Quantum Dipoles
Zhu, Bihui; Xu, Minghui; Urbina, Felipe H; Restrepo, Juan G; Holland, Murray J; Rey, Ana Maria
2015-01-01
Macroscopic ensembles of radiating dipoles are ubiquitous in the physical and natural sciences. In the classical limit the dipoles can be described as damped-driven oscillators, which are able to spontaneously synchronize and collectively lock their phases. Here we investigate the correspond- ing phenomenon in the quantum regime with arrays of quantized two-level systems coupled via long-range and anisotropic dipolar interactions. Our calculations demonstrate that the dipoles may overcome the decoherence induced by quantum fluctuations and inhomogeneous couplings and evolve to a synchronized steady-state. This steady-state bears much similarity to that observed in classical systems, and yet also exhibits genuine quantum properties such as quantum correlations and quan- tum phase diffusion (reminiscent of lasing). Our predictions could be relevant for the development of better atomic clocks and a variety of noise tolerant quantum devices.
Community Benchmarking of Tsunami-Induced Nearshore Current Models
Lynett, P. J.; Wilson, R. I.; Gately, K.
2015-12-01
To help produce accurate and consistent maritime hazard products, the National Tsunami Hazard Mitigation Program (NTHMP) Strategic Plan includes a requirement to develop and run a benchmarking workshop to evaluate the numerical tsunami modeling of currents. For this workshop, five different benchmarking datasets were organized. These datasets were selected based on characteristics such as geometric complexity, currents that are shear/separation driven (and thus are de-coupled from the incident wave forcing), tidal coupling, and interaction with the built environment. While tsunami simulation models have generally been well validated against wave height and runup, comparisons with speed data are much less common. As model results are increasingly being used to estimate or indicate damage to coastal infrastructure, understanding the accuracy and precision of speed predictions becomes of important. As a result of this 2-day workshop held in early 2015, modelers now have a better awareness of their ability to accurately capture the physics of tsunami currents, and therefore a better understanding of how to use these simulation tools for hazard assessment and mitigation efforts. In this presentation, the model results - from 14 different modelers - will be presented and summarized, with a focus on statistical and ensemble properties of the current predictions.
Probability of detection models for eddy current NDE methods
Energy Technology Data Exchange (ETDEWEB)
Rajesh, S.N.
1993-04-30
The development of probability of detection (POD) models for a variety of nondestructive evaluation (NDE) methods is motivated by a desire to quantify the variability introduced during the process of testing. Sources of variability involved in eddy current methods of NDE include those caused by variations in liftoff, material properties, probe canting angle, scan format, surface roughness and measurement noise. This thesis presents a comprehensive POD model for eddy current NDE. Eddy current methods of nondestructive testing are used widely in industry to inspect a variety of nonferromagnetic and ferromagnetic materials. The development of a comprehensive POD model is therefore of significant importance. The model incorporates several sources of variability characterized by a multivariate Gaussian distribution and employs finite element analysis to predict the signal distribution. The method of mixtures is then used for estimating optimal threshold values. The research demonstrates the use of a finite element model within a probabilistic framework to the spread in the measured signal for eddy current nondestructive methods. Using the signal distributions for various flaw sizes the POD curves for varying defect parameters have been computed. In contrast to experimental POD models, the cost of generating such curves is very low and complex defect shapes can be handled very easily. The results are also operator independent.
Chromoelectric Dipole Moments of Quarks in MSSM Extensions
Aboubrahim, Amin; Nath, Pran; Zorik, Anas
2015-01-01
An analysis is given of the chromoelectric dipole moment of quarks and of the neutron in an MSSM extension where the matter sector contains an extra vectorlike generation of quarks and mirror quarks. The analysis includes contributions to the CEDM from the exchange of the $W$ and the $Z$ bosons, from the exchange of charginos and neutralinos and the gluino. Their contribution to the EDM of quarks is investigated. The interference between the MSSM sector and the new sector with vectorlike quarks is investigated. It is shown that inclusion of the vectorlike quarks can modify the quark EDMs in a significant way. Further, this interference also provides a probe of the vectorlike quark sector. These results are of interest as in the future measurements on the neutron EDM could see an improvement up to two orders of magnitude over the current experimental limits and provide a window to new physics beyond the standard model.
Energy Technology Data Exchange (ETDEWEB)
Bagley, G. P.
1980-01-01
An SCR DC to DC converter is described which will operate at an output of 275 kW and will supply current to electron storage ring magnets requiring 5 h stability of 50 ppM. The operation of this modified chopper is described and design equations are presented, along with the system control loop description.
Flavor Changing Neutral Currents in a Realistic Composite Technicolor Model
Carone, C D; Carone, Christopher D.; Hamilton, Rowan T.
1993-01-01
We consider the phenomenology of a composite technicolor model proposed recently by Georgi. Composite technicolor interactions produce four-quark operators in the low energy theory that contribute to flavor changing neutral current processes. While we expect operators of this type to be induced at the compositeness scale by the flavor-symmetry breaking effects of the preon mass matrices, the Georgi model also includes operators from higher scales that are not GIM-suppressed. Since these operators are potentially large, we study their impact on flavor changing neutral currents and CP violation in the neutral $B$, $D$, and $K$ meson systems.
Permanent Electric Dipole Moments of Single-, Two-, and Three-Nucleon Systems
Wirzba, Andreas; Nogga, Andreas
2016-01-01
A nonzero electric dipole moment (EDM) of the neutron, proton, deuteron or helion, in fact, of any finite system necessarily involves the breaking of a symmetry, either by the presence of external fields (i.e. electric fields leading to the case of induced EDMs) or explicitly by the breaking of the discrete parity and time-reflection symmetries in the case of permanent EDMs. We discuss two theorems describing these phenomena and report about the cosmological motivation for an existence of CP breaking beyond what is generated by the Kobayashi-Maskawa mechanism in the Standard Model and what this might imply for the permanent electric dipole moments of the nucleon and light nuclei by estimating a window of opportunity for physics beyond what is currently known. Recent - and in the case of the deuteron even unpublished - results for the relevant matrix elements of nuclear EDM operators are presented and the relevance for disentangling underlying New Physics sources are discussed.
Dzuba, V A
2016-01-01
Hyperfine-induced electric dipole contributions may significantly increase probabilities of otherwise very weak electric octupole and magnetic quadrupole atomic clock transitions (e.g. transitions between $s$ and $f$ electron orbitals). These transitions can be used for exceptionally accurate atomic clocks, quantum information processing and search for dark matter. They are very sensitive to new physics beyond the Standard Model, such as temporal variation of the fine structure constant, the Lorentz invariance and Einstein equivalence principle violation. We formulate conditions under which the hyperfine-induced electric dipole contribution dominates. Due to the hyperfine quenching the electric octupole clock transition in $^{173}$Yb$^+$ is two orders of magnitude stronger than that in currently used $^{171}$Yb$^+$. Some enhancement is found in $^{143}$Nd$^{13+}$, $^{149}$Pm$^{14+}$, $^{147}$Sm$^{14+}$, and $^{147}$Sm$^{15+}$ ions.
Quench calculations for the superconducting dipole magnet of CBM experiment at FAIR
Kurilkin, P.; Akishin, P.; Bychkov, A.; Floch, E.; Gusakov, Yu.; Ladygin, V.; Malakhov, A.; Moritz, G.; Ramakers, H.; Senger, P.; Shabunov, A.; Szwangruber, P.; Toral, F.
2016-08-01
The scientific mission of the Compressed Baryonic Matter (CBM) experiment is the study of the nuclear matter properties at the high baryon densities in heavy ion collisions at the Facility of Antiproton and Ion Research (FAIR) in Darmstadt. The 5.15 MJ superconducting dipole magnet will be used in the silicon tracking system of the CBM detector. It will provide a magnetic field integral of 1 Tm which is required to obtain a momentum resolution of 1% for the track reconstruction. This paper presents quench modeling and evaluation of candidate protection schemes for the CBM dipole magnet. Two quench programs based on finite-difference method were used in simulation. One of them is currently used at GSI, and the other based on CIEMAT (Madrid, Spain) was modified to perform quench calculation for the CBM magnet.
One-Dimensional Modelling of Marine Current Turbine Runaway Behaviour
Directory of Open Access Journals (Sweden)
Staffan Lundin
2016-04-01
Full Text Available If a turbine loses its electrical load, it will rotate freely and increase speed, eventually achieving that rotational speed which produces zero net torque. This is known as a runaway situation. Unlike many other types of turbine, a marine current turbine will typically overshoot the final runaway speed before slowing down and settling at the runaway speed. Since the hydrodynamic forces acting on the turbine are dependent on rotational speed and acceleration, turbine behaviour during runaway becomes important for load analyses during turbine design. In this article, we consider analytical and numerical models of marine current turbine runaway behaviour in one dimension. The analytical model is found not to capture the overshoot phenomenon, while still providing useful estimates of acceleration at the onset of runaway. The numerical model incorporates turbine wake build-up and predicts a rotational speed overshoot. The predictions of the models are compared against measurements of runaway of a marine current turbine. The models are also used to recreate previously-published results for a tidal turbine and applied to a wind turbine. It is found that both models provide reasonable estimates of maximum accelerations. The numerical model is found to capture the speed overshoot well.
Comparison of analytical eddy current models using principal components analysis
Contant, S.; Luloff, M.; Morelli, J.; Krause, T. W.
2017-02-01
Monitoring the gap between the pressure tube (PT) and the calandria tube (CT) in CANDU® fuel channels is essential, as contact between the two tubes can lead to delayed hydride cracking of the pressure tube. Multifrequency transmit-receive eddy current non-destructive evaluation is used to determine this gap, as this method has different depths of penetration and variable sensitivity to noise, unlike single frequency eddy current non-destructive evaluation. An Analytical model based on the Dodd and Deeds solutions, and a second model that accounts for normal and lossy self-inductances, and a non-coaxial pickup coil, are examined for representing the response of an eddy current transmit-receive probe when considering factors that affect the gap response, such as pressure tube wall thickness and pressure tube resistivity. The multifrequency model data was analyzed using principal components analysis (PCA), a statistical method used to reduce the data set into a data set of fewer variables. The results of the PCA of the analytical models were then compared to PCA performed on a previously obtained experimental data set. The models gave similar results under variable PT wall thickness conditions, but the non-coaxial coil model, which accounts for self-inductive losses, performed significantly better than the Dodd and Deeds model under variable resistivity conditions.
Flavor changing neutral currents in a realistic composite technicolor model
Carone, Christopher D.; Hamilton, Rowan T.
1993-03-01
We consider the phenomenology of a composite technicolor model proposed recently by Georgi. Composite technicolor interactions produce four-quark operators in the low energy theory that contribute to flavor changing neutral current processes. While we expect operators of this type to be induced at the compositeness scale by the flavor-symmetry breaking effects of the preon mass matrices, the Georgi model also includes operators from higher scales that are not GIM-suppressed. Since these operators are potentially large, we study their impact on flavor changing neutral currents and CP violation in the neutral K, B, and D meson systems. Notably, we find that this model gives rise to a typical value for {ɛ‧}/{ɛ} that is much smaller than most standard model estimates.
Current Concepts: Mouse Models of Sjögren's Syndrome
Directory of Open Access Journals (Sweden)
Tegan N. Lavoie
2011-01-01
Full Text Available Sjögren's syndrome (SjS is a complex chronic autoimmune disease of unknown etiology which primarily targets the exocrine glands, resulting in eventual loss of secretory function. The disease can present as either primary SjS or secondary SjS, the latter of which occurs concomitantly with another autoimmune disease such as rheumatoid arthritis, systemic lupus erythematosus, scleroderma, or primary biliary cirrhosis. Current advancements in therapeutic prevention and treatment for SjS are impeded by lack of understanding in the pathophysiological and clinical progression of the disease. Development of appropriate mouse models for both primary and secondary SjS is needed in order to advance knowledge of this disease. This paper details important features, advantages, and pitfalls of current animal models of SjS, including spontaneous, transgenic, knockout, immunization, and transplantation chimera mouse models, and emphasizes the need for a better model in representing the human SjS phenotype.
Analogue Behavioral Modeling of Switched-Current Building Block Circuits
Institute of Scientific and Technical Information of China (English)
ZENG Xuan; WANG Wei; SHI Jianlei; TANG Pushan; D.ZHOU
2001-01-01
This paper proposes a behavioral modeling technique for the second-generation switched-current building block circuits. The proposed models are capable of capturing the non-ideal behavior of switched-current circuits, which includes the charge injection effects and device mismatch effects. As a result, system performance degradations due to the building block imperfections can be detected at the early design stage by fast behavioral simulations. To evaluate the accuracy of the proposed models, we developed a time-domain behavioral simulator. Experimental results have shown that compared with SPICE, the behavioral modeling error is less than 2.15%, while behavioral simulation speed up is 4 orders in time-domain.
Animal models of frailty: current applications in clinical research.
Kane, Alice E; Hilmer, Sarah N; Mach, John; Mitchell, Sarah J; de Cabo, Rafael; Howlett, Susan E
2016-01-01
The ethical, logistical, and biological complications of working with an older population of people inherently limits clinical studies of frailty. The recent development of animal models of frailty, and tools for assessing frailty in animal models provides an invaluable opportunity for frailty research. This review summarizes currently published animal models of frailty including the interleukin-10 knock-out mouse, the mouse frailty phenotype assessment tool, and the mouse clinical frailty index. It discusses both current and potential roles of these models in research into mechanisms of frailty, interventions to prevent/delay frailty, and the effect of frailty on outcomes. Finally, this review discusses some of the challenges and opportunities of translating research findings from animals to humans.
Numeral eddy current sensor modelling based on genetic neural network
Institute of Scientific and Technical Information of China (English)
Yu A-Long
2008-01-01
This paper presents a method used to the numeral eddy current sensor modelling based on the genetic neural network to settle its nonlinear problem. The principle and algorithms of genetic neural network are introduced. In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network (GNN) according to measurement data. So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network. The nonlinear model has the advantages of strong robustness,on-line modelling and high precision.The maximum nonlinearity error can be reduced to 0.037% by using GNN.However, the maximum nonlinearity error is 0.075% using the least square method.
A turbidity current model for real world applications
Macías, Jorge; Castro, Manuel J.; Morales, Tomás
2016-04-01
Traditional turbidity current models suffer from several drawbacks. Among them not preserving freshwater mass, a missing pressure term, or not including terms related to deposition, erosion and entrainment in the momentum equation. In Morales et al.(2009) a new turbidity current model was proposed trying to overcome all these drawbacks. This model takes into account the interaction between the turbidity current and the bottom, considering deposition and erosion effects as well as solid bedload transport of particles at the bed due to the current. Moreover, this model includes the effects of the deposition, erosion and water entrainment into the momentum equation,commonly neglected in this type of models and, finally, in the absence of water entrainment, freshwater mass in the turbidity current is preserved. Despite these improvements, the numerical results obtained by this model when applied to real river systems were not satisfactory due to the simple form of the friction term that was considered. In the present work we propose a different parameterization of this term, where bottom and interface fluid frictions are separately parameterized with more complex expressions. Moreover, the discretization of the deposition/erosion terms is now performed semi-implicitly which guarantees the positivity of the volumetric concentration of sediments in suspension and in the erodible sediment layer at the bed. The numerical simulations obtained with this new turbidity current model (component of HySEA numerical computing platform) greatly improve previous numerical results for simplified geometries as well as for real river systems. Acknowledgements: This research has been partially supported by the Junta de Andalucía research project TESELA (P11-RNM7069) and the Spanish Government Research project DAIFLUID (MTM2012-38383-C02-01) and Universidad de Málaga, Campus de Excelencia Andalucía TECH. References: T. Morales, M. Castro, C. Parés, and E. Fernández-Nieto (2009). On
Modeling and strain gauging of eddy current repulsion deicing systems
Smith, Samuel O.
1993-01-01
Work described in this paper confirms and extends work done by Zumwalt, et al., on a variety of in-flight deicing systems that use eddy current repulsion for repelling ice. Two such systems are known as electro-impulse deicing (EIDI) and the eddy current repulsion deicing strip (EDS). Mathematical models for these systems are discussed for their capabilities and limitations. The author duplicates a particular model of the EDS. Theoretical voltage, current, and force results are compared directly to experimental results. Dynamic strain measurements results are presented for the EDS system. Dynamic strain measurements near EDS or EIDI coils are complicated by the high magnetic fields in the vicinity of the coils. High magnetic fields induce false voltage signals out of the gages.
Current fluctuations in a two dimensional model of heat conduction
Pérez-Espigares, Carlos; Garrido, Pedro L.; Hurtado, Pablo I.
2011-03-01
In this work we study numerically and analytically current fluctuations in the two-dimensional Kipnis-Marchioro-Presutti (KMP) model of heat conduction. For that purpose, we use a recently introduced algorithm which allows the direct evaluation of large deviations functions. We compare our results with predictions based on the Hydrodynamic Fluctuation Theory (HFT) of Bertini and coworkers, finding very good agreement in a wide interval of current fluctuations. We also verify the existence of a well-defined temperature profile associated to a given current fluctuation which depends exclusively on the magnitude of the current vector, not on its orientation. This confirms the recently introduced Isometric Fluctuation Relation (IFR), which results from the time-reversibility of the dynamics, and includes as a particular instance the Gallavotti-Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by timereversibility on the statistics of nonequilibrium fluctuations.
Current Models and Innovative Strategies in Management Education in China.
Wang, Zhong-Ming
1999-01-01
Current models of management education in China include national training, on-the-job technical training, and the national master's of business administration supervisory committee. Effective strategies being used include teamwork, process skills, action learning, cross-cultural management learning, and competency-based management development. (SK)
Hypersonic Vehicle Tracking Based on Improved Current Statistical Model
Directory of Open Access Journals (Sweden)
He Guangjun
2013-11-01
Full Text Available A new method of tracking the near space hypersonic vehicle is put forward. According to hypersonic vehicles’ characteristics, we improved current statistical model through online identification of the maneuvering frequency. A Monte Carlo simulation is used to analyze the performance of the method. The results show that the improved method exhibits very good tracking performance in comparison with the old method.
Gompertz kinetics model of fast chemical neurotransmission currents.
Easton, Dexter M
2005-10-01
At a chemical synapse, transmitter molecules ejected from presynaptic terminal(s) bind reversibly with postsynaptic receptors and trigger an increase in channel conductance to specific ions. This paper describes a simple but accurate predictive model for the time course of the synaptic conductance transient, based on Gompertz kinetics. In the model, two simple exponential decay terms set the rates of development and decline of transmitter action. The first, r, triggering conductance activation, is surrogate for the decelerated rate of growth of conductance, G. The second, r', responsible for Y, deactivation of the conductance, is surrogate for the decelerated rate of decline of transmitter action. Therefore, the differential equation for the net conductance change, g, triggered by the transmitter is dg/dt=g(r-r'). The solution of that equation yields the product of G(t), representing activation, and Y(t), which defines the proportional decline (deactivation) of the current. The model fits, over their full-time course, published records of macroscopic ionic current associated with fast chemical transmission. The Gompertz model is a convenient and accurate method for routine analysis and comparison of records of synaptic current and putative transmitter time course. A Gompertz fit requiring only three independent rate constants plus initial current appears indistinguishable from a Markov fit using seven rate constants.
[Neither Descartes nor Freud? current pain models in psychosomatic medicine].
Egloff, N; Egle, U T; von Känel, R
2008-05-14
Models explaining chronic pain based on the mere presence or absence of peripheral somatic findings or which view pain of psychological origin when there is no somatic explanation, have their shortcomings. Current scientific knowledge calls for distinct pain concepts, which integrate neurobiological and neuropsychological aspects of pain processing.
Particle electric dipole-moments
Energy Technology Data Exchange (ETDEWEB)
Pendlebury, J.M. [Sussex Univ., Brighton (United Kingdom)
1997-04-01
The incentive to detect particle electric dipole-moments, as a window on time-reversal violation, remains undiminished. Efforts to improve the measurements for the neutron, the electron and some nuclei are still making rapid progress as more powerful experimental methods are brought to bear. A new measurement for the neutron at ILL is presented. (author). 7 refs.
Schildknecht, Dieter
2016-01-01
We give a brief representation of the theoretical results from the color dipole picture, covering the total photoabsorption cross section, high-energy $J/\\psi$ photoproduction with respect to recent experimental data from the LHCb Collaboration at CERN, and ultra-high energy neutrino scattering, relevant for the ICE-CUBE experiment.
DEFF Research Database (Denmark)
Andersen, Jørgen Bach
2006-01-01
A number of antenna topics may be treated by studying just two parallel, closely spaced electrical dipoles. They form an array and they may be coupled to form a single antenna with one port, or coupled through a coupling network to form a multiport antenna. The situations discussed are the creation...
Field Quality and Mechanical Analysis of the Beam Separation Dipole for HL-LHC Upgrade
AUTHOR|(CDS)2086334; Nakamoto, Tatsushi; Xu, Q; Kawamata, H; Todesco, Ezio
2015-01-01
High luminosity upgrade of the Large Hadron Collider (HL-LHC) project has been launched to attain a ten times higher integrated luminosity than the current LHC that has been in operation for over ten years. For this goal, the quadruple and dipole magnets around two interaction points, the ATLAS and the CMS, will be upgraded. High Energy Accelerator Research Organization (KEK) is in charge of developing the new superconducting beam separation dipole magnet (D1). The main dipole field of 5.6 T in a large aperture of 150 mm is generated using a cos-theta coil wound with Nb-Ti cables at nominal operating current of 12.0 kA at 1.9 K corresponding to 75% of the load line ratio. The main challenges for the D1 are larger aperture, a high level of iron saturation, radiation resistance, and tight constraints on field quality. This article summarizes the results of a detailed analysis on field error. Electromagnetic simulation with ROXIE was carried out for the 2-D model of the new D1. As possible design changes, a diam...
Terahertz Radiation from Large Aperture Bulk Semi-insulating GaAs Photoconductive Dipole Antenna
Institute of Scientific and Technical Information of China (English)
施卫; 贾婉丽; 侯磊; 许景周; 张希成
2004-01-01
We report the experimental results of a large-aperture biased semi-insulating GaAs photoconductive dipole antenna, with a gap of 3mm between two Au/Ge/Ni electrodes, triggered by 800nm Ti-sapphire laser pulses with 82 MHz repetition rate. A direct comparison is made between insulated GaAs dipole antenna with a Si3N4 layer and bare GaAs dipole antenna. Both the current in the antenna and the radiation amplitude present as linear to the exciting power when the applied voltage is fixed. The Si3N4 insulated GaAs dipole antenna can hold higher biased voltage than a normal GaAs dipole antenna; its terahertz radiation generation efficiency is significantly higher than that of a normal GaAs dipole antenna.
Analytical Modeling for the Grating Eddy Current Displacement Sensors
Directory of Open Access Journals (Sweden)
Lv Chunfeng
2015-02-01
Full Text Available As a new type of displacement sensor, grating eddy current displacement sensor (GECDS combines traditional eddy current sensors and grating structure in one. The GECDS performs a wide range displacement measurement without precision reduction. This paper proposes an analytical modeling approach for the GECDS. The solution model is established in the Cartesian coordinate system, and the solving domain is limited to finite extents by using the truncated region eigenfunction expansion method. Based on the second order vector potential, expressions for the electromagnetic field as well as coil impedance related to the displacement can be expressed in closed-form. Theoretical results are then confirmed by experiments, which prove the suitability and effectiveness of the analytical modeling approach.
Numerical Model for Conduction-Cooled Current Lead Heat Loads
White, M J; Brueck, H D; 10.1063/1.4706965
2012-01-01
Current leads are utilized to deliver electrical power from a room temperature junction mounted on the vacuum vessel to a superconducting magnet located within the vacuum space of a cryostat. There are many types of current leads used at laboratories throughout the world, however, conduction-cooled current leads are often chosen for their simplicity and reliability. Conduction-cooled leads have the advantage of using common materials, have no superconducting/normal state transition, and have no boil-off vapor to collect. The XFEL (X-Ray Free Electron Laser) magnets are operated at 2 K, which makes vapor-cooled current leads impractical due to the sub-atmospheric bath pressure. This paper presents a numerical model for conduction-cooled current lead heat loads. This model takes into account varying material and fluid thermal properties, varying thicknesses along the length of the lead, heat transfer in the circumferential and longitudinal directions, electrical power dissipation, and the effect of thermal inte...
The Dependence of the Field Decay on the Powering History of the LHC Superconducting Dipole Magnets
Sammut, N; Micallef, J; Sanfilippo, S
2006-01-01
The decay of the allowed multipoles in the Large Hadron Collider (LHC) dipoles is expected to perturb the beam stability during the particle injection. The decay amplitude is largely affected by the powering history of the magnet and is particularly dependent on the pre-cycle flat-top current and duration as well as the pre-injection preparation duration. With possible prospects of having different genres of cycles during the LHC operation, the powering history effect must be taken into account in the Field Description Model for the LHC and must hence be corrected during machine operation. This paper presents the results of the modelling of this phenomenon.
Magnetic dipole states in /sup 206/Pb
Energy Technology Data Exchange (ETDEWEB)
Ponomarev, V.; Vdovin, A.; Velchev, Ch.
1987-12-01
The fragmentation of the magnetic dipole strength in /sup 206/Pb is studied in the framework of the quasiparticle-phonon nuclear model. The calculations reproduce the two-humped shape of the experimental distribution. As in /sup 208/Pb there is an isoscalar 1/sup +/ state at Esub(x) approx. = 5.7 MeV in /sup 206/Pb and its wavefunction contains sizable two-photon components. It is shown that direct transitions from the ground state to two-phonon 1/sup +/ states give a negligible contribution to the total excitation probability of the M1 resonance.
Double giant dipole resonance in hot nuclei
Energy Technology Data Exchange (ETDEWEB)
Cinausero, M.; Rizzi, V.; Viesti, G.; Fabris, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pesente, S.; Barbui, M.; Fioretto, E.; Prete, G.; Bracco, A.; Camera, F.; Million, B.; Leoni, S.; Wieland, O.; Benzoni, G.; Brambilla, S.; Airoldi, A.; Maj, A.; Kmiecik, M
2004-02-09
Signals from Double Dipole Giant Resonances (DGDR) in hot nuclei have been searched in a {gamma}-{gamma} coincidence experiment using the HECTOR array at the Laboratori Nazionali di Legnaro. The experimental single {gamma}-ray spectrum and the projection of the {gamma}-{gamma} matrix have been compared with a standard Monte Carlo Statistical Model code including only the single GDR excitation. These calculations have been used as background to determine the extra-yield associated with the DGDR de-excitation. Results have been compared with a previous experiment confirming the presence of the DGDR excitation in fusion-evaporation reactions.
Electric Dipole Moments and New Physics
Cirigliano, Vincenzo
2014-09-01
In this talk I will focus mostly on the role of electric dipole moments (EDMs) as probes of physics beyond the Standard Model (BSM). In the first part of the talk I will present an overview of the physics reach of various searches and I will discuss the complementarity of different EDM probes. In the second part of the talk I will discuss recent work on the computation of the BSM-induced nucleon EDM and the T-odd pion-nucleon couplings using lattice Quantum ChromoDynamics.
Refutation of stability proofs for dipole vortices
DEFF Research Database (Denmark)
Nycander, J.
1992-01-01
Five stability proofs for dipole vortices (modons) that have been presented by various authors are examined. It is shown that they are all incorrect, and that westward-propagating dipoles are in fact unstable, in contradiction to some of the proofs.......Five stability proofs for dipole vortices (modons) that have been presented by various authors are examined. It is shown that they are all incorrect, and that westward-propagating dipoles are in fact unstable, in contradiction to some of the proofs....
Giant dipole resonance in hot rotating nuclei
Energy Technology Data Exchange (ETDEWEB)
Chakrabarty, D.R. [Bhabha Atomic Research Centre, Nuclear Physics Division, Mumbai (India); Dinh Dang, N. [RIKEN, Nishina Centre for Accelerator-based Science, Saitama (Japan); VINATOM, Institute of Nuclear Science and Technique, Hanoi (Viet Nam); Datar, V.M. [Tata Institute of Fundamental Research, INO Cell, Mumbai (India)
2016-05-15
Over the last several decades, extensive experimental and theoretical work has been done on the giant dipole resonance (GDR) in excited nuclei covering a wide range of temperature (T), angular momentum (J) and nuclear mass. A reasonable stability of the GDR centroid energy and an increase of the GDR width with T (in the range∝1-3 MeV) and J are the two well-established results. Some experiments have indicated the saturation of the GDR width at high T. The gradual disappearance of the GDR vibration at much higher T has been observed. Experiments on the Jacobi transition and the GDR built on superdeformed shapes at high rotational frequencies have been reported in a few cases. Theoretical calculations on the damping of the collective dipole vibration, characterised by the GDR width, have been carried out within various models such as the thermal shape fluctuation model and the phonon damping model. These models offer different interpretations of the variation of the GDR width with T and J and have met with varying degrees of success in explaining the experimental data. In this review, the present experimental and theoretical status in this field is discussed along with the future outlook. The interesting phenomenon of the pre-equilibrium GDR excitation in nuclear reactions is briefly addressed. (orig.)
Quantum Zeno suppression of dipole-dipole forces
Wüster, Sebastian
2016-01-01
We consider inter-atomic forces due to resonant dipole-dipole interactions within a dimer of highly excited Rydberg atoms, embedded in an ultra-cold gas. These forces rely on a coherent superposition of two-atom electronic states, which is destroyed by continuous monitoring of the dimer state through a detection scheme utilizing controllable interactions with the background gas atoms. We show that this intrinsic decoherence of the molecular energy surface can gradually deteriorate a repulsive dimer state, causing a mixing of attractive and repulsive character. For sufficiently strong decoherence, a Zeno-like effect causes a complete arrest of interatomic forces. We finally show how short decohering pulses can controllably redistribute population between the different molecular energy surfaces.
Effects of dipole-dipole interaction on entanglement transfer
Institute of Scientific and Technical Information of China (English)
Guo Hong; Xiong Heng-Na
2008-01-01
A system consisting of two different atoms interacting with a two-mode vacuum, where each atom is resonant only with one cavity mode, is considered.The effects of dipole-dipole (dd) interaction between two atoms on the atom-atom entanglement and mode-mode entanglement are investigated. For a weak dd interaction, when the atoms are initially separable, the entanglement between them can be induced by the dd interaction, and the entanglement transfer between the atoms and the modes occurs efficiently; when the atoms are initially entangled, the entanglement transfer is almost not influenced by the dd interaction. However, for a strong dd interaction, it is difficult to transfer the entanglement from the atoms to the modes, but the atom-atom entanglement can be maintained when the atoms are initially entangled.
Noncommutative Dipole Field Theories And Unitarity
Chiou, D W; Chiou, Dah-Wei; Ganor, Ori J.
2004-01-01
We extend the argument of Gomis and Mehen for violation of unitarity in field theories with space-time noncommutativity to dipole field theories. In dipole field theories with a timelike dipole vector, we present 1-loop amplitudes that violate the optical theorem. A quantum mechanical system with nonlocal potential of finite extent in time also shows violation of unitarity.
Findlay, R P; Dimbylow, P J
2009-04-21
If an antenna is located close to a person, the electric and magnetic fields produced by the antenna will vary in the region occupied by the human body. To obtain a mean value of the field for comparison with reference levels, the Institute of Electrical and Electronic Engineers (IEEE) and International Commission on Non-Ionizing Radiation Protection (ICNIRP) recommend spatially averaging the squares of the field strength over the height the body. This study attempts to assess the validity and accuracy of spatial averaging when used for half-wave dipoles at frequencies between 65 MHz and 2 GHz and distances of lambda/2, lambda/4 and lambda/8 from the body. The differences between mean electric field values calculated using ten field measurements and that of the true averaged value were approximately 15% in the 600 MHz to 2 GHz range. The results presented suggest that the use of modern survey equipment, which takes hundreds rather than tens of measurements, is advisable to arrive at a sufficiently accurate mean field value. Whole-body averaged and peak localized SAR values, normalized to calculated spatially averaged fields, were calculated for the NORMAN voxel phantom. It was found that the reference levels were conservative for all whole-body SAR values, but not for localized SAR, particularly in the 1-2 GHz region when the dipole was positioned very close to the body. However, if the maximum field is used for normalization of calculated SAR as opposed to the lower spatially averaged value, the reference levels provide a conservative estimate of the localized SAR basic restriction for all frequencies studied.
Review of the electric dipole moment of light nuclei
Yamanaka, Nodoka
2016-01-01
In this review, we summarize the theoretical development on the electric dipole moment of light nuclei. We first describe the nucleon level CP violation and its parametrization. We then present the results of calculations of the EDM of light nuclei in the ab initio approach and in the cluster model. The analysis of the effect of several models beyond standard model is presented, together with the prospects for its discovery. The advantage of the electric dipole moment of light nuclei is focused in the point of view of the many-body physics. The evaluations of the nuclear electric dipole moment generated by the $\\theta$-term and by the CP phase of the Cabibbo-Kobayashi-Maskawa matrix are also reviewed.
Properties of the superconductor in accelerator dipole magnets
Teravest, Derk
Several aspects of the application of superconductors to high field dipole magnets for particle accelerators are discussed. The attention is focused on the 10 tesla (1 m model) magnet that is envisaged for the future Large Hadron Collider (LHC) accelerator. The basic motivation behind the study is the intention of employing superconductors to their utmost performance. An overview of practical supercomputers, their applications and their impact on high field dipole magnets used for particle accelerators, is presented. The LHC reference design for the dipole magnets is outlined. Several models were used to study the influence of a number of factors in the shape and in particular, the deviation from the shape that is due to the flux flow state. For the investigated extrinsic and intrinsic factors, a classification can be made with respect to the effect on the shape of the characteristic of a multifilamentary wire. The optimization of the coil structure for high field dipole magnets, with respect to the field quality is described. An analytical model for solid and hollow filaments, to calculate the effect of filament magnetization in the quality of the dipole field, is presented.
Critical behavior of isotropic three-dimensional systems with dipole-dipole interactions
Energy Technology Data Exchange (ETDEWEB)
Belim, S. M., E-mail: sbelim@mail.ru [Dostoevsky Omsk State University (Russian Federation)
2013-06-15
The critical behavior of Heisenberg magnets with dipole-dipole interactions near the line of second-order phase transitions directly in three-dimensional space is investigated in terms of a field-theoretic approach. The dependences of critical exponents on the dipole-dipole interaction parameter are derived. Comparison with experimental facts is made.
A fluid mechanical model for current-generating-feeding jellyfish
Peng, Jifeng; Dabiri, John
2008-11-01
Many jellyfish species, e.g. moon jellyfish Aurelia aurita, use body motion to generate fluid currents which carry their prey to the vicinity of their capture appendages. In this study, a model was developed to understand the fluid mechanics for this current-generating-feeding mode of jellyfish. The flow generated by free-swimming Aurelia aurita was measured using digital particle image velocimetry. The dynamics of prey (e.g., brine shrimp Artemia) in the flow field were described by a modified Maxey-Riley equation which takes into consideration the inertia of prey and the escape forces, which prey exert in the presence of predator. A Lagrangian analysis was used to identify the region of the flow in which prey can be captured by the jellyfish and the clearance rate was quantified. The study provides a new methodology to study biological current-generating-feeding and the transport and mixing of particles in fluid flow in general.
3-dimensional current collection model. [of Tethered Satellite System 1
Hwang, Kai-Shen; Shiah, A.; Wu, S. T.; Stone, N.
1992-01-01
A three-dimensional, time dependent current collection model of a satellite has been developed for the TSS-1 system. The system has been simulated particularly for the Research of Plasma Electrodynamics (ROPE) experiment. The Maxwellian distributed particles with the geomagnetic field effects are applied in this numerical simulation. The preliminary results indicate that a ring current is observed surrounding the satellite in the equatorial plane. This ring current is found between the plasma sheath and the satellite surface and is oscillating with a time scale of approximately 1 microsec. This is equivalent to the electron plasma frequency. An hour glass shape of electron distribution was observed when the viewing direction is perpendicular to the equatorial plane. This result is consistent with previous findings from Linson (1969) and Antoniades et al. (1990). Electrons that are absorbed by the satellite are limited from the background ionosphere as indicated by Parker and Murphy (1967).
Directory of Open Access Journals (Sweden)
N. Aquilina
2012-03-01
Full Text Available It is well known that in a superconducting accelerator a significant chromaticity drift can be induced by the decay of the sextupolar component of the main dipoles. In this paper we give a brief overview of what was expected for the Large Hadron Collider (LHC on the grounds of magnetic measurements of individual dipoles carried out during the production. According to this analysis, the decay time constants were of the order of 200 s: since the injection in the LHC starts at least 30 minutes after the magnets are at constant current, the dynamic correction of this effect was not considered to be necessary. The first beam measurements of chromaticity showed significant decay even after a few hours. For this reason, a dynamic correction of decay on the injection plateau was implemented based on beam measurements. This means that during the injection plateau the sextupole correctors are powered with a varying current to cancel out the decay of the dipoles. This strategy has been implemented successfully. A similar phenomenon has been observed for the dependence of the decay amplitude on the powering history of the dipoles: according to magnetic measurements, also in this case time constants are of the order of 200 s and therefore no difference is expected between a one hour or a ten hours flattop. On the other hand, the beam measurements show a significant change of decay for these two conditions. For the moment there is no clue of the origin of these discrepancies. We give a complete overview of the two effects, and the modifications that have been done to the field model parameters to be able to obtain a final chromaticity correction within a few units.
Institute of Scientific and Technical Information of China (English)
田永红; 彭金生
2001-01-01
研究了非线性双光子Jaynes-Cummings(J-C)模型系统中原子偶极矩高阶压缩的时间演化特性及其产生条件。结果表明，在弱场条件下，原子偶极矩色散或吸收分量的二阶和六阶量子涨落可被周期性压缩，非线性修正项或失谐量以及热噪声对压缩程度有显著的影响。%The time evolution properties of higher-order squeezing of atomic dipole and its producing conditions in the nonlinear two-photon Jaynes-Cummings model are studied. It is shown that the two-order and six-order quantum fluctuation of the branch part of the atomic dipole chromatic dispersion or absorption can be periodically squeezed in a weak intensity field. The nonlinear correction term, the two-photon frequency detuning and thermal noise have a remarkable influence on the squeezing.
Minimum Q Electrically Small Spherical Magnetic Dipole Antenna - Theory
DEFF Research Database (Denmark)
Breinbjerg, Olav; Kim, Oleksiy S.
2009-01-01
The stored energies, radiated power, and quality factor of a magnetic-dipole antenna, consisting of a spherical electrical surface current density enclosing a magnetic core, is obtained through direct spatial integration of the internally and externally radiated field expressed in terms of spheri...
Passive Target Tracking Based on Current Statistical Model
Institute of Scientific and Technical Information of China (English)
DENG Xiao-long; XIE Jian-ying; YANG Yu-pu
2005-01-01
Bearing-only passive tracking is regarded as a nonlinear hard tracking problem. There are still no completely good solutions to this problem until now. Based on current statistical model, the novel solution to this problem utilizing particle filter (PF) and the unscented Kalman filter (UKF) is proposed. The new solution adopts data fusion from two observers to increase the observability of passive tracking. It applies the residual resampling step to reduce the degeneracy of PF and it introduces the Markov Chain Monte Carlo methods (MCMC) to reduce the effect of the "sample impoverish". Based on current statistical model, the EKF, the UKF and particle filter with various proposal distributions are compared in the passive tracking experiments with two observers. The simulation results demonstrate the good performance of the proposed new filtering methods with the novel techniques.
Energy current loss instability model on a computer
Edighoffer, John A.
1995-04-01
The computer program called Energy Stability in a Recirculating Accelerator (ESRA) Free Electron Laser (FEL) has been written to model bunches of particles in longitudinal phase space transversing a recirculating accelerator and the associated rf changes and aperture current losses. This energy-current loss instability was first seen by Los Alamos's FEL group in their energy recovery experiments. This code addresses these stability issues and determines the transport, noise, feedback and other parameters for which these FEL systems are stable or unstable. Two representative systems are modeled, one for the Novosibirisk high power FEL racetrack microtron for photochemical research, the other is the CEBAF proposed UV FEL system. Both of these systems are stable with prudent choices of parameters.
Charge and Current in the Quantum Hall Matrix Model
2003-01-01
We extend the quantum Hall matrix model to include couplings to external electric and magnetic fields. The associated current suffers from matrix ordering ambiguities even at the classical level. We calculate the linear response at low momenta -- this is unambigously defined. In particular, we obtain the correct fractional quantum Hall conductivity, and the expected density modulations in response to a weak and slowly varying magnetic field. These results show that the classical quantum Hall ...
Considering digits in a current model of numerical development.
Roesch, Stephanie; Moeller, Korbinian
2014-01-01
Numerical cognition has long been considered the perfect example of abstract information processing. Nevertheless, there is accumulating evidence in recent years suggesting that the representation of number magnitude may not be entirely abstract but may present a specific case of embodied cognition rooted in the sensory and bodily experiences of early finger counting and calculating. However, so far none of the existing models of numerical development considers the influence of finger-based representations. Therefore, we make first suggestions on (i) how finger-based representations may be integrated into a current model of numerical development; and (ii) how they might corroborate the acquisition of basic numerical competencies at different development levels.
Modeling the heliospheric current sheet: Solar cycle variations
Riley, Pete; Linker, J. A.; Mikić, Z.
2002-07-01
In this report we employ an empirically driven, three-dimensional MHD model to explore the evolution of the heliospheric current sheet (HCS) during the course of the solar cycle. We compare our results with a simpler ``constant-speed'' approach for mapping the HCS outward into the solar wind to demonstrate that dynamic effects can substantially deform the HCS in the inner heliosphere (ballerina skirt,'' we discuss an interval approaching the maximum of solar cycle 23 (Carrington rotations 1960 and 1961) when the shape would be better described as ``conch shell''-like. We use Ulysses magnetic field measurements to support the model results.
Pion electromagnetic current in a light-front model
Pacheco-Bicudo-Cabral de Melo, J; Frederico, T
1999-01-01
The electromagnetic form factor of the pion is calculated in a pseudoscalar field theoretical model which constituent quarks. We extract the form factor using the "+" component of the electromagnetic current in the light-cone formalism. For comparison, we also compute the form factor in the covariant framework and we obtain perfect agreement. It is shown that the pair terms do not contribute in this pseudoscalar model. This explains why a naive light-cone calculation, i.e., omitting pair terms from the onset, also yields the same results.
Current state of genome-scale modeling in filamentous fungi
DEFF Research Database (Denmark)
Brandl, Julian; Andersen, Mikael Rørdam
2015-01-01
The group of filamentous fungi contains important species used in industrial biotechnology for acid, antibiotics and enzyme production. Their unique lifestyle turns these organisms into a valuable genetic reservoir of new natural products and biomass degrading enzymes that has not been used to full...... testing them in vivo. The increasing availability of high quality models and molecular biological tools for manipulating filamentous fungi renders the model-guided engineering of these fungal factories possible with comprehensive metabolic networks. A typical fungal model contains on average 1138 unique...... metabolic reactions and 1050 ORFs, making them a vast knowledge-base of fungal metabolism. In the present review we focus on the current state as well as potential future applications of genome-scale models in filamentous fungi....
Persistent current in an almost staggered Harper model
Vasserman, A.; Berkovits, R.
2015-08-01
In this paper we study the persistent current (PC) of a staggered Harper model, close to the half-filling. The Harper model is different than other one dimensional disordered systems which are always localized, since it is a quasi-periodic system with correlated disorder resulting in the fact that it can be in the metallic regime. Nevertheless, the PC for a wide range of parameters of the Harper model does not show typical metallic behavior, although the system is in the metallic regime. This is a result of the nature of the central band states, which are a hybridization of Gaussian states localized in superlattice points. When the superlattice is not commensurate with the system length, the PC behaves as an insulator. Thus even in the metallic regime a typical finite Harper model may exhibit a PC expected from an insulator.
Modeling Electric Current Flow in 3D Fractured Media
Demirel, S.; Roubinet, D.; Irving, J.
2014-12-01
The study of fractured rocks is extremely important in a variety of research fields and applications such as hydrogeology, hydrocarbon extraction and long-term storage of toxic waste. As fractures are highly conductive structures in comparison to the surrounding rock, their presence can be either an advantage or a drawback. For hydrocarbon extraction, fractures allow for quick and easy access to the resource whereas for toxic waste storage their presence increases the risk of leakage and migration of pollutants. In both cases, the identification of fracture network characteristics is an essential step. Recently, we have developed an approach for modeling electric current flow in 2D fractured media. This approach is based on a discrete-dual-porosity model where fractures are represented explicitly, the matrix is coarsely discretized into blocks, and current flow exchange between the fractures and matrix is analytically evaluated at the fracture-scale and integrated at the block-scale [1]. Although this approach has shown much promise and has proven its efficiency for 2D simulations, its extension to 3D remains to be addressed. To this end, we assume that fractures can be represented as two-dimensional finite planes embedded in the surrounding matrix, and we express analytically the distribution of electric potential at the fracture scale. This fracture-scale expression takes into account the electric-current-flow exchange with the surrounding matrix and flow conservation is enforced at the fracture intersections. The fracture-matrix exchange is then integrated at the matrix-block scale where the electric current flow conservation at the block boundaries is formulated with a modified finite volume method. With the objective of providing a low-computational-cost modeling approach adapted to 3D simulations in fractured media, our model is (i) validated and compared to existing modeling approaches and, (ii) used to evaluate the impact of the presence of fractures on
3D Design & Simulation of Printed Dipole Antenna
Directory of Open Access Journals (Sweden)
Protap Mollick
2015-09-01
Full Text Available This paper represents design of a printed dipole antenna with both lambda by 2 & half dipole. In this research paper the impedance increases with combined design on the FR-4 substrate and ground plane. The main feature of printed dipole antenna is there is a feeder between the radiant elements. Average impedance about 73 ohm, which is very large form other antenna. For vertical earth position impedance decreases about 36 ohm. Applied AC voltage forwarding bias dipole antenna gains are high but when reverse bias condition gains are low. Between ropes to station there is need extra insulator that abate high impedance current flow to dipole antenna. Feed lines are approximately 75 ohm and the main length between two poles are 143 meter. The radius of two pole line is very thin it’s about 2.06 meter. Transmission lines are added in the last portion of feed lines, which situated apposite of two poles. Designs are simulated by hfss and solving equations are done my matlab.
Homology Modeling a Fast Tool for Drug Discovery: Current Perspectives
Vyas, V. K.; Ukawala, R. D.; Ghate, M.; Chintha, C.
2012-01-01
Major goal of structural biology involve formation of protein-ligand complexes; in which the protein molecules act energetically in the course of binding. Therefore, perceptive of protein-ligand interaction will be very important for structure based drug design. Lack of knowledge of 3D structures has hindered efforts to understand the binding specificities of ligands with protein. With increasing in modeling software and the growing number of known protein structures, homology modeling is rapidly becoming the method of choice for obtaining 3D coordinates of proteins. Homology modeling is a representation of the similarity of environmental residues at topologically corresponding positions in the reference proteins. In the absence of experimental data, model building on the basis of a known 3D structure of a homologous protein is at present the only reliable method to obtain the structural information. Knowledge of the 3D structures of proteins provides invaluable insights into the molecular basis of their functions. The recent advances in homology modeling, particularly in detecting and aligning sequences with template structures, distant homologues, modeling of loops and side chains as well as detecting errors in a model contributed to consistent prediction of protein structure, which was not possible even several years ago. This review focused on the features and a role of homology modeling in predicting protein structure and described current developments in this field with victorious applications at the different stages of the drug design and discovery. PMID:23204616
Wang, Qian; Hua, Ning; Tang, Xue-Zheng; Lu, Hong; Ma, Ping; Tang, Fa-Kuan
2010-08-01
This paper constructs a concentric ellipsoid torso-heart model by boundary element method and investigates the impacts of model structures on the cardiac magnetic fields generated by both equivalent primary source-a current dipole and volume currents. Then by using the simulated magnetic fields based on the torso-heart model as input, the cardiac current sources-an array of current dipoles by optimal constrained linear inverse method are constructed. Next, the current dipole array reconstruction considering boundaries are compared with that in an unbounded homogeneous medium. Furthermore, the influence of random noise on reconstruction is also considered and the reconstructing effect is judged by several reconstructing parameters.
Scattering from rough thin films: discrete-dipole-approximation simulations.
Parviainen, Hannu; Lumme, Kari
2008-01-01
We investigate the wave-optical light scattering properties of deformed thin circular films of constant thickness using the discrete-dipole approximation. Effects on the intensity distribution of the scattered light due to different statistical roughness models, model dependent roughness parameters, and uncorrelated, random, small-scale porosity of the inhomogeneous medium are studied. The suitability of the discrete-dipole approximation for rough-surface scattering problems is evaluated by considering thin films as computationally feasible rough-surface analogs. The effects due to small-scale inhomogeneity of the scattering medium are compared with the analytic approximation by Maxwell Garnett, and the results are found to agree with the approximation.
Valence Topological Charge-Transfer Indices for Dipole Moments
Directory of Open Access Journals (Sweden)
Francisco Torrens
2003-01-01
Full Text Available New valence topological charge-transfer indices are applied to the calculation of dipole moments. The algebraic and vector semisum charge-transfer indices are defined. The combination of the charge-transfer indices allows the estimation of the dipole moments. The model is generalized for molecules with heteroatoms. The ability of the indices for the description of the molecular charge distribution is established by comparing them with the dipole moments of a homologous series of phenyl alcohols. Linear and non-linear correlation models are obtained. The new charge-transfer indices improve the multivariable non-linear regression equations for the dipole moment. When comparing with previous results, the variance decreases 92%. No superposition of the corresponding GkÃ¢Â€Â“Jk and GkV Ã¢Â€Â“ JkV pairs is observed. This diminishes the risk of co-linearity. Inclusion of the oxygen atom in the p-electron system is beneficial for the description of the dipole moment, owing to either the role of the additional p orbitals provided by the heteroatom or the role of steric factors in the p-electron conjugation. Linear and non-linear correlations between the fractal dimension and various descriptors point not only to a homogeneous molecular structure but also to the ability to predict and tailor drug properties.
Constraining the neutrino magnetic dipole moment from white dwarf pulsations
Córsico, Alejandro H; Bertolami, Marcelo M Miller; Kepler, S O; García-Berro, Enrique
2014-01-01
Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. By comparing the theoretical rate of change of period expected for this star with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment. Our upper limit for the neutrino magnetic dipole moment is somewhat less restrictive than, but still compat...
A skull-based multiple dipole phantom for EEG and MEG studies
Energy Technology Data Exchange (ETDEWEB)
Spencer, M.E.; Leahy, R.M. [University of Southern California, Los Angeles, CA (United States); Mosher, J.C. [Los Alamos National Lab., NM (United States)
1996-07-01
A versatile phantom for use in evaluating forward and inverse methods for MEG and EEG has been designed and is currently being constructed. The phantom consists of three major components: (i) a 32-element cur- rent dipole array, (ii) a PC-controlled dipole driver with 32 isolated channels allowing independent control of each dipole, (iii) spherical and human-skull mounts in which the dipole array is placed. Materials were selected throughout the phantom to produce minimal field distortions and artifacts to enable acquisition of high quality EEG and MEG data. The dipoles are made from a rigid narrow (0.84 mm) stainless steel coax cable. The dipole drivers can be configured as either current or voltage sources, are independently programmable and fully isolated, and are capable of producing arbitrary bipolar waveforms up to a 200 Hz bandwidth. The spherical mount is a single shell sphere filled with conductive gelatin. The human skull mount has three shells: ``brain`` (conducting gelatin), ``skull`` (the skull is impregnated with a low conductivity conducting gelatin), and ``scalp`` (a thin layer of rubber latex mixed with NaCl to achieve a conductivity matched to the brain). The conductivities will be adjusted to achieve approximately an 80:1:80 ratio. Data collected to date from the spherical phantom shows excellent agreement between measured surface potentials and that predicted from theory (27 of the 32 dipoles give better than 99.9% rms fit) and negligible leakage between dipoles. We are currently completing construction of the skull mount.
Chromomagnetic dipole moment of the top quark revisited
Energy Technology Data Exchange (ETDEWEB)
Martinez, R. [Universidad Nacional, Departamento de Fisica, Bogota (Colombia); Perez, M.A. [Cinvestav - IPN, Departamento de Fisica, Merida (Mexico); Poveda, N. [Universidad Nacional, Departamento de Fisica, Bogota (Colombia); Universidad Pedagogica y Tecnologica de Colombia, Departamento de Fisica, Tunja (Colombia)
2008-01-15
We study the complete one-loop contributions to the chromagnetic dipole moment {delta}{kappa} of the top quark in the standard model, two Higgs doublet models, topcolor assisted technicolor models, 331 models and extended models with a single extra dimension. We find that the SM predicts {delta}{kappa}=-0.056 and the predictions of the other models are also consistent with the constraints imposed on {delta}{kappa} by low-energy precision measurements. (orig.)
Monolayer patterning using ketone dipoles.
Kim, Min Kyoung; Xue, Yi; Pašková, Tereza; Zimmt, Matthew B
2013-08-14
The self-assembly of multi-component monolayers with designed patterns requires molecular recognition among components. Dipolar interactions have been found to influence morphologies of self-assembled monolayers and can affect molecular recognition functions. Ketone groups have large dipole moments (2.6 D) and are easily incorporated into molecules. The potential of ketone groups for dipolar patterning has been evaluated through synthesis of two 1,5-disubstituted anthracenes bearing mono-ketone side chains, STM characterization of monolayers self-assembled from their single and two component solutions and molecular mechanics simulations to determine their self-assembly energetics. The results reveal that (i) anthracenes bearing self-repulsive mono-ketone side chains assemble in an atypical monolayer morphology that establishes dipolar attraction, instead of repulsion, between ketones in adjacent side chains; (ii) pairs of anthracene molecules whose self-repulsive ketone side chains are dipolar complementary spontaneously assemble compositionally patterned monolayers, in which the two components segregate into neighboring, single component columns, driven by side chain dipolar interactions; (iii) compositionally patterned monolayers also assemble from dipolar complementary anthracene pairs that employ different dipolar groups (ketones or CF2 groups) in their side chains; (iv) the ketone group, with its larger dipole moment and size, provides comparable driving force for patterned monolayer formation to that of the smaller dipole, and smaller size, CF2 group.
Isoscalar dipole transition as a probe for asymmetric clustering
Chiba, Y; Taniguchi, Y
2015-01-01
Background: The sharp $1^-$ resonances with enhanced isoscalar dipole transition strengths are observed in many light nuclei at relatively small excitation energies, but their nature was unclear. Purpose: We show those resonances can be attributed to the cluster states with asymmetric configurations such as $\\alpha$+$^{16}{\\rm O}$. We explain why asymmetric cluster states are strongly excited by the isoscalar dipole transition. We also provide a theoretical prediction of the isoscalar dipole transitions in $^{20}{\\rm Ne}$ and $^{44}{\\rm Ti}$. Method: The transition matrix is analytically derived to clarify the excitation mechanism. The nuclear model calculations by Brink-Bloch wave function and antisymmetrized molecular dynamics are also performed to provide a theoretical prediction for $^{20}{\\rm Ne}$ and $^{44}{\\rm Ti}$. Results: It is shown that the transition matrix is as large as the Weisskopf estimate even though the ground state is an ideal shell model state. Furthermore, it is considerably amplified i...
11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades
Energy Technology Data Exchange (ETDEWEB)
Zlobin, A. V. [Fermilab; Andreev, N. [Fermilab; Apollinari, G. [Fermilab; Auchmann, B. [CERN; Barzi, E. [Fermilab; Izquierdo Bermudez, S. [CERN; Bossert, R. [Fermilab; Buehler, M. [Fermilab; Chlachidze, G. [Fermilab; DiMarco, J. [Fermilab; Karppinen, M. [CERN; Nobrega, F. [Fermilab; Novitski, I. [CERN; Rossi, L. [CERN; Smekens, D. [CERN; Tartaglia, M. [Fermilab; Turrioni, D. [Fermilab; Velev, Genadi [Fermilab
2015-01-01
FNAL and CERN are developing a twin-aperture 11 T Nb3Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.
Simulation of current generation in a 3-D plasma model
Energy Technology Data Exchange (ETDEWEB)
Tsung, F.S.; Dawson, J.M. [Univ. of California, Los Angeles, CA (United States)
1996-12-31
Two wires carrying current in the same direction will attract each other, and two wires carrying current in the opposite direction will repel each other. Now, consider a test charge in a plasma. If the test charge carries current parallel to the plasma, then it will be pulled toward the plasma core, and if the test charge carries current anti-parallel to the plasma, then it will be pushed to the edge. The electromagnetic coupling between the plasma and a test charge (i.e., the A{sub {parallel}} {circ} v{sub {parallel}} term in the test charge`s Hamiltonian) breaks the symmetry in the parallel direction, and gives rise to a diffusion coefficient which is dependent on the particle`s parallel velocity. This is the basis for the {open_quotes}preferential loss{close_quotes} mechanism described in the work by Nunan et al. In our previous 2+{1/2}D work, in both cylindrical and toroidal geometries, showed that if the plasma column is centrally fueled, then an initial current increases steadily. The results in straight, cylindrical plasmas showed that self generated parallel current arises without trapped particle or neoclassical diffusion, as assumed by the bootstrap theory. It suggests that the fundamental mechanism seems to be the conservation of particles canonical momenta in the direction of the ignorable coordinate. We have extended the simulation to 3D to verify the model put forth. A scalable 3D EM-PIC code, with a localized field-solver, has been implemented to run on a large class of parallel computers. On the 512-node SP2 at Cornell Theory Center, we have benchmarked the 2+{1/2}D calculations using 32 grids in the previously ignored direction, and a 100-fold increase in the number of particles. Our preliminary results show good agreements between the 2+{1/2}D and the 3D calculations. We will present our 3D results at the meeting.
Modeling of leakage currents in high-k dielectrics
Energy Technology Data Exchange (ETDEWEB)
Jegert, Gunther Christian
2012-03-15
Leakage currents are one of the major bottlenecks impeding the downscaling efforts of the semiconductor industry. Two core devices of integrated circuits, the transistor and, especially, the DRAM storage capacitor, suffer from the increasing loss currents. In this perspective a fundamental understanding of the physical origin of these leakage currents is highly desirable. However, the complexity of the involved transport phenomena so far has prevented the development of microscopic models. Instead, the analysis of transport through the ultra-thin layers of high-permittivity (high-k) dielectrics, which are employed as insulating layers, was carried out at an empirical level using simple compact models. Unfortunately, these offer only limited insight into the physics involved on the microscale. In this context the present work was initialized in order to establish a framework of microscopic physical models that allow a fundamental description of the transport processes relevant in high-k thin films. A simulation tool that makes use of kinetic Monte Carlo techniques was developed for this purpose embedding the above models in an environment that allows qualitative and quantitative analyses of the electronic transport in such films. Existing continuum approaches, which tend to conceal the important physics behind phenomenological fitting parameters, were replaced by three-dimensional transport simulations at the level of single charge carriers. Spatially localized phenomena, such as percolation of charge carriers across pointlike defects, being subject to structural relaxation processes, or electrode roughness effects, could be investigated in this simulation scheme. Stepwise a self-consistent, closed transport model for the TiN/ZrO{sub 2} material system, which is of outmost importance for the semiconductor industry, was developed. Based on this model viable strategies for the optimization of TiN/ZrO{sub 2}/TiN capacitor structures were suggested and problem areas
North Indian Ocean variability during the Indian Ocean dipole
Directory of Open Access Journals (Sweden)
J. Brown
2008-06-01
Full Text Available The circulation in the North Indian Ocean (NIO henceforth is highly seasonally variable. Periodically reversing monsoon winds (southwesterly during summer and northeasterly during winter give rise to seasonally reversing current systems off the coast of Somalia and India. In addition to this annual monsoon cycle, the NIO circulation varies semiannually because of equatorial currents reversing four times each year. These descriptions are typical, but how does the NIO circulation behave during anomalous years, during an Indian Ocean dipole (IOD for instance? Unfortunately, in situ observational data are rather sparse and reliance has to be placed on numerical models to understand this variability. In this paper, we estimate the surface current variability from a 12-year hindcast of the NIO for 1993–2004 using a 1/2^{°} resolution circulation model that assimilates both altimetric sea surface height anomalies and sea surface temperature. Presented in this paper is an examination of surface currents in the NIO basin during the IOD. During the non-IOD period of 2000–2004, the typical equatorial circulation of the NIO reverses four times each year and transports water across the basin preventing a large sea surface temperature difference between the western and eastern NIO. Conversely, IOD years are noted for strong easterly and westerly wind outbursts along the equator. The impact of these outbursts on the NIO circulation is to reverse the direction of the currents – when compared to non-IOD years – during the summer for negative IOD events (1996 and 1998 and during the fall for positive IOD events (1994 and 1997. This reversal of current direction leads to large temperature differences between the western and eastern NIO.
Semiparametric Additive Transformation Model under Current Status Data
Cheng, Guang
2011-01-01
We consider the efficient estimation of the semiparametric additive transformation model with current status data. A wide range of survival models and econometric models can be incorporated into this general transformation framework. We apply the B-spline approach to simultaneously estimate the linear regression vector, the nondecreasing transformation function, and a set of nonparametric regression functions. We show that the parametric estimate is semiparametric efficient in the presence of multiple nonparametric nuisance functions. An explicit consistent B-spline estimate of the asymptotic variance is also provided. All nonparametric estimates are smooth, and shown to be uniformly consistent and have faster than cubic rate of convergence. Interestingly, we observe the convergence rate interfere phenomenon, i.e., the convergence rates of B-spline estimators are all slowed down to equal the slowest one. The constrained optimization is not required in our implementation. Numerical results are used to illustra...
Modeling of finite aspect ratio effects on current drive
Energy Technology Data Exchange (ETDEWEB)
Wright, J.C.; Phillips, C.K. [Princeton Plasma Physics Lab., NJ (United States)
1996-12-31
Most 2D RF modeling codes use a parameterization of current drive efficiencies to calculate fast wave driven currents. This parameterization assumes a uniform diffusion coefficient and requires a priori knowledge of the wave polarizations. These difficulties may be avoided by a direct calculation of the quasilinear diffusion coefficient from the Kennel-Englemann form with the field polarizations calculated by a full wave code. This eliminates the need to use the approximation inherent in the parameterization. Current profiles are then calculated using the adjoint formulation. This approach has been implemented in the FISIC code. The accuracy of the parameterization of the current drive efficiency, {eta}, is judged by a comparison with a direct calculation: where {chi} is the adjoint function, {epsilon} is the kinetic energy, and {rvec {Gamma}} is the quasilinear flux. It is shown that for large aspect ratio devices ({epsilon} {r_arrow} 0), the parameterization is nearly identical to the direct calculation. As the aspect ratio approaches unity, visible differences between the two calculations appear.
Advances in modeling of lower hybrid current drive
Peysson, Y.; Decker, J.; Nilsson, E.; Artaud, J.-F.; Ekedahl, A.; Goniche, M.; Hillairet, J.; Ding, B.; Li, M.; Bonoli, P. T.; Shiraiwa, S.; Madi, M.
2016-04-01
First principle modeling of the lower hybrid (LH) current drive in tokamak plasmas is a longstanding activity, which is gradually gaining in accuracy thanks to quantitative comparisons with experimental observations. The ability to reproduce simulatenously the plasma current and the non-thermal bremsstrahlung radial profiles in the hard x-ray (HXR) photon energy range represents in this context a significant achievement. Though subject to limitations, ray tracing calculations are commonly used for describing wave propagation in conjunction with Fokker-Planck codes, as it can capture prominent features of the LH wave dynamics in a tokamak plasma-like toroidal refraction. This tool has been validated on several machines when the full absorption of the LH wave requires the transfer of a small fraction of power from the main lobes of the launched power spectrum to a tail at a higher parallel refractive index. Conversely, standard modeling based on toroidal refraction only becomes more challenging when the spectral gap is large, except if other physical mechanisms may dominate to bridge it, like parametric instabilities, as suggested for JET LH discharges (Cesario et al 2004 Phys. Rev. Lett. 92 175002), or fast fluctuations of the launched power spectrum or ‘tail’ LH model, as shown for Tore Supra (Decker et al 2014 Phys. Plasma 21 092504). The applicability of the heuristic ‘tail’ LH model is investigated for a broader range of plasma parameters as compared to the Tore Supra study and with different LH wave characteristics. Discrepancies and agreements between simulations and experiments depending upon the different models used are discussed. The existence of a ‘tail’ in the launched power spectrum significantly improves the agreement between modeling and experiments in plasma conditions for which the spectral gap is large in EAST and Alcator C-Mod tokamaks. For the Alcator C-Mod tokamak, the experimental evolution of the HXR profiles with density suggests
Massive fermion model in 3d and higher spin currents
Bonora, L; Prester, P Dominis; de Souza, B Lima; Smolic, I
2016-01-01
We analyze the 3d free massive fermion theory coupled to external sources. The presence of a mass explicitly breaks parity invariance. We calculate two- and three-point functions of a gauge current and the energy momentum tensor and, for instance, obtain the well-known result that in the IR limit (but also in the UV one) we reconstruct the relevant CS action. We then couple the model to higher spin currents and explicitly work out the spin 3 case. In the UV limit we obtain an effective action which was proposed many years ago as a possible generalization of spin 3 CS action. In the IR limit we derive a different higher spin action. This analysis can evidently be generalized to higher spins. We also discuss the conservation and properties of the correlators we obtain in the intermediate steps of our derivation.
Modeling of current distribution on smooth and columnar platinum structures.
Zinola, Carlos F
2011-01-17
Studying the growth and stability of anisotropic or isotropic disordered surfaces in electrodeposition is of importance in catalytic electrochemistry. In some cases, the metallic nature of the electrode defines the topography and roughness, which are also controlled by the experimental time and applied external potential. Because of the experimental restrictions in conventional electrochemical techniques and ex situ electron microscopies, a theoretical model of the surface geometry could aid in understanding the electrodeposition process and current distributions. In spite of applying a complex theory such as dynamic scaling method or perturbation theories, the resolution of mixed mass-/charge-transfer equations (tertiary distribution) for the electrodeposition process would give reliable information. One of the main problems with this type of distribution is the mathematics when solving the spatial n-dimensional differential equations. Use of a primary current distribution is proposed here to simplify the differential equations; however it limits wide application of the first assumption. Distributions of concentration profile, current density, and electrode potential are presented here as a function of the distance normal to the surface for the cases of smooth and rough platinum growth. In the particular case of columnar surfaces, cycloid curves are used to model the electrode, from which the concentration profile is presented in a parameterized form after solving a first-type curvilinear integral. The concentration contour results in a combination of a trigonometric inverse function and a linear distribution leading to a negative concavity curve. The calculation of the current density and electrode potential contours also show trigonometric shapes exhibiting forbidden imaginary values only at the minimal values of the trochoid curve.
Directory of Open Access Journals (Sweden)
J.O. Adepitan
2012-05-01
Full Text Available The study is aimed at determining the dependence of the current along a channel on the model used, assuming the same base current. We compared three transmission-line-type models, namely: Transmission Line (TL, Modified Transmission Line with Linear decay, Modified Transmission Line with Exponential decay and two traveling-current-source-type models: Bruce-Golde (BG and Traveling Current Source (TCS models. The current profiles along the channel at different heights predicted by these models are presented and discussed. Comparison is based on the assumption that all the models have the same base current. It was found that at low heights and within a time window frame of 15 :s, the currents of the transmission-line-type models predict a zero value at one time or the other with a maximum turning point following some 1:s after. A linear relationship is predicted between the current peak and the channel height. A discontinuity of current peak was observed at high heights. No zero value of current was recorded in case of TCS both at low and high channel heights.
Optics effects of splitting dipole magnets into several thin lenses
Leunissen, L H A
1998-01-01
The evaluation of the dynamic aperture and the calculation of non linear optics parameters have been made so far with the simplest model of dipole, i.e. a single thin lens positioned at the centre of each thick dipole. It was shown recently that the non-linear chromaticity decreases significantly when the thick lens is represented by two thin lenses or more instead of one. In this note the study is extended to amplitude detuning and dynamic aperture. Unlike the observation reported on non-linear chromatic detuning we find no significant changes for the dynamic aperture and amplitude d etuning when the dipole magnets are split in more than one thin lens. Furthermore, non-uniform azimuthal distribution of the multipoles inside the dipole is shown not to change the above-mentio ned results. In both cases, the influence of the beta-funtions is expected to give large effect for a given dipole. However, integrated over one cell this effect is shown to compensate to a large extent. erture reported on non-linear chro...
Preferential rotation of chiral dipoles in isotropic turbulence
Kramel, Stefan; Toschi, Federico; Voth, Greg A
2016-01-01
Particles in the shape of chiral dipoles show a preferential rotation in three dimensional homogeneous isotropic turbulence. A chiral dipole consists of a rod with two helices of opposite handedness, one at each end. We can use 3d printing to fabricate these particles with length in the inertial range and track their rotations in a turbulent flow between oscillating grids. High aspect ratio chiral dipoles will align with the extensional eigenvectors of the strain rate tensor and the helical ends will respond to the strain field by spinning around its long axis. The mean of the measured spinning rate is non-zero and reflects the average stretching the particles experience. We use Stokesian dynamics simulations of chiral dipoles in pure strain flow to quantify the dependence of spinning on particle shape. Based on the known response to pure strain, we build a model that gives the spinning rate of small chiral dipoles using Lagrangian velocity gradients from high resolution direct numerical simulations. The stat...
Directory of Open Access Journals (Sweden)
Thiago C. F. Gomes
2008-01-01
Full Text Available The first computational implementation that automates the procedures involved in the calculation of infrared intensities using the charge-charge flux-dipole flux model is presented. The atomic charges and dipoles from the Quantum Theory of Atoms in Molecules (QTAIM model was programmed for Morphy98, Gaussian98 and Gaussian03 programs outputs, but for the ChelpG parameters only the Gaussian programs are supported. Results of illustrative but new calculations for the water, ammonia and methane molecules at the MP2/6-311++G(3d,3p theoretical level, using the ChelpG and QTAIM/Morphy charges and dipoles are presented. These results showed excellent agreement with analytical results obtained directly at the MP2/6-311++G(3d,3p level of theory.
Salehi, A.; Aftabi, S.
2016-02-01
In this paper, in a new approach, we study the stability of the dynamical system (DS) of R1+ɛ in terms of two significant cosmological parameters, deceleration parameter and jerk parameter {q,j}. Other cosmographic parameters such as (l,s,…) have been obtained in terms of these two parameters. We have obtained critical points (qe,je), the best fitted current values of cosmographic parameters (q0,j0,l0,s0), best value for model parameter ɛ and best trajectory of dynamics of system in phase space by simultaneously solving the DS and best fitting the parameter by the SNIa data. By defining modified redshift in anisotropic cosmological model as 1 + z(t,p̂) = a(t0) a(t) (1 - A(n̂ ṡp̂)) (where A is a magnitude of anisotropy, n̂ is direction of privileged axis and p̂ is the direction of each SNe Ia sample to galactic coordinates), the luminosity distance has been obtained in terms of modified redshift using cosmography method. Using union 2 data, we have found the direction of privileged axis in the galactic coordinate. The results show that the magnitude of anisotropy is about |A|≃ 10-3 and the direction of privileged axis is (l,b) = (298+34-34, 2 +23-23). Also, our results are consistent with other studies in 1 - σ confidence level.
Animal models of transcranial direct current stimulation: Methods and mechanisms.
Jackson, Mark P; Rahman, Asif; Lafon, Belen; Kronberg, Gregory; Ling, Doris; Parra, Lucas C; Bikson, Marom
2016-11-01
The objective of this review is to summarize the contribution of animal research using direct current stimulation (DCS) to our understanding of the physiological effects of transcranial direct current stimulation (tDCS). We comprehensively address experimental methodology in animal studies, broadly classified as: (1) transcranial stimulation; (2) direct cortical stimulation in vivo and (3) in vitro models. In each case advantages and disadvantages for translational research are discussed including dose translation and the overarching "quasi-uniform" assumption, which underpins translational relevance in all animal models of tDCS. Terminology such as anode, cathode, inward current, outward current, current density, electric field, and uniform are defined. Though we put key animal experiments spanning decades in perspective, our goal is not simply an exhaustive cataloging of relevant animal studies, but rather to put them in context of ongoing efforts to improve tDCS. Cellular targets, including excitatory neuronal somas, dendrites, axons, interneurons, glial cells, and endothelial cells are considered. We emphasize neurons are always depolarized and hyperpolarized such that effects of DCS on neuronal excitability can only be evaluated within subcellular regions of the neuron. Findings from animal studies on the effects of DCS on plasticity (LTP/LTD) and network oscillations are reviewed extensively. Any endogenous phenomena dependent on membrane potential changes are, in theory, susceptible to modulation by DCS. The relevance of morphological changes (galvanotropy) to tDCS is also considered, as we suggest microscopic migration of axon terminals or dendritic spines may be relevant during tDCS. A majority of clinical studies using tDCS employ a simplistic dose strategy where excitability is singularly increased or decreased under the anode and cathode, respectively. We discuss how this strategy, itself based on classic animal studies, cannot account for the
Operational advances in ring current modeling using RAM-SCB
Energy Technology Data Exchange (ETDEWEB)
Welling, Daniel T [Los Alamos National Laboratory; Jordanova, Vania K [Los Alamos National Laboratory; Zaharia, Sorin G [Los Alamos National Laboratory; Morley, Steven K [Los Alamos National Laboratory
2010-12-03
The Ring current Atmosphere interaction Model with Self-Consistently calculated 3D Magnetic field (RAM-SCB) combines a kinetic model of the ring current with a force-balanced model of the magnetospheric magnetic field to create an inner magnetospheric model that is magnetically self consistent. RAM-SCB produces a wealth of outputs that are valuable to space weather applications. For example, the anisotropic particle distribution of the KeV-energy population calculated by the code is key for predicting surface charging on spacecraft. Furthermore, radiation belt codes stand to benefit substantially from RAM-SCB calculated magnetic field values and plasma wave growth rates - both important for determining the evolution of relativistic electron populations. RAM-SCB is undergoing development to bring these benefits to the space weather community. Data-model validation efforts are underway to assess the performance of the system. 'Virtual Satellite' capability has been added to yield satellite-specific particle distribution and magnetic field output. The code's outer boundary is being expanded to 10 Earth Radii to encompass previously neglected geosynchronous orbits and allow the code to be driven completely by either empirical or first-principles based inputs. These advances are culminating towards a new, real-time version of the code, rtRAM-SCB, that can monitor the inner magnetosphere conditions on both a global and spacecraft-specific level. This paper summarizes these new features as well as the benefits they provide the space weather community.
Energy Technology Data Exchange (ETDEWEB)
Elert, M. [Kemakta Konsult AB, Stockholm (Sweden)
1999-05-01
The `Aespoe task force on modelling of groundwater flow and transport of solutes` is a forum for the international organisations supporting the Aespoe HRL Project. The purpose of the Task Force is to interact in the area of conceptual and numerical modelling of groundwater flow and solute transport in fractured rock. Task 4 of the Aespoe Modelling Task Force consists of modelling exercises in support of the TRUE-1 tracer tests. In this report, the modelling work performed within Tasks 4C and 4D is evaluated, which comprised predictive modelling of the radially converging tracer tests and dipole tracer tests performed within the TRUE-1 tests using non-sorbing tracers. The tests were performed between packed off boreholes penetrating a water-conducting geological feature with a simple structure (Feature A). These tests are to a great extent preparatory steps for the subsequent tests with sorbing radioactive tracers. In Tasks 4E and 4F of the Aespoe Modelling Task Force predictive modelling of the sorbing tracer tests is performed. Eight modelling teams representing seven organisations have performed predictive modelling using different modelling approaches and models. The modelling groups were initially given data from the site characterisation and data on the experimental set-up of the tracer tests. Based on this information model predictions were performed of drawdown, tracer mass recovery and tracer breakthrough. The performed predictions shows that the concept of Feature A as a singular well-connected feature with limited connectivity to its surroundings is quite adequate for predictions of drawdown in boreholes and conservative tracer breakthrough. Reasonable estimates were obtained using relatively simple models. However, more elaborate models with calibration or conditioning of transmissivities and transport apertures are required for more accurate predictions. The general flow and transport processes are well understood, but the methodology to derive the
Current state of genome-scale modeling in filamentous fungi.
Brandl, Julian; Andersen, Mikael R
2015-06-01
The group of filamentous fungi contains important species used in industrial biotechnology for acid, antibiotics and enzyme production. Their unique lifestyle turns these organisms into a valuable genetic reservoir of new natural products and biomass degrading enzymes that has not been used to full capacity. One of the major bottlenecks in the development of new strains into viable industrial hosts is the alteration of the metabolism towards optimal production. Genome-scale models promise a reduction in the time needed for metabolic engineering by predicting the most potent targets in silico before testing them in vivo. The increasing availability of high quality models and molecular biological tools for manipulating filamentous fungi renders the model-guided engineering of these fungal factories possible with comprehensive metabolic networks. A typical fungal model contains on average 1138 unique metabolic reactions and 1050 ORFs, making them a vast knowledge-base of fungal metabolism. In the present review we focus on the current state as well as potential future applications of genome-scale models in filamentous fungi.
Morita, Takaumi; Katoh, Keiichi; Breedlove, Brian K; Yamashita, Masahiro
2013-12-02
Using a fused phthalocyaninato ligand to control the spatial arrangement of Tb(III) moieties in Tb(III) single-molecule magnets (SMMs), we could control the dipole-dipole interactions in the molecules and prepared the first tetranuclear Tb(III) SMM complex. [Tb(obPc)2]Tb(Fused-Pc)Tb[Tb(obPc)2] (abbreviated as [Tb4]; obPc = 2,3,9,10,16,17,23,24-octabutoxyphthalocyaninato, Fused-Pc = bis{7(2),8(2),12(2),13(2),17(2),18(2)-hexabutoxytribenzo[g,l,q]-5,10,15,20-tetraazaporphirino}[b,e]benzenato). In direct-current magnetic susceptibility measurements, ferromagnetic interactions among the four Tb(3+) ions were observed. In [Tb4], there are two kinds of magnetic dipole-dipole interactions. One is strong interactions in the triple-decker moieties, which dominate the magnetic relaxations, and the other is the weak one through the fused phthalocyaninato (Pc) ligand linking the two triple-decker complexes. In other words, [Tb4] can be described as a weakly ferromagnetically coupled dimer of triple-decker Tb2(obPc)3 complexes with strong dipole-dipole interactions in the triple-decker moieties and weak ones through the fused phthalocyaninato ligand linking the two triple-decker complexes. For [Tb4], dual magnetic relaxation processes were observed similar to other dinuclear Tb(III)Pc complexes. The relaxation processes are due to the anisotropic centers. This is clear evidence that the magnetic relaxation mechanism depends heavily on the dipole-dipole (f-f) interactions between the Tb(3+) ions in the systems. Through a better understanding of the magnetic dipole-dipole interactions obtained in these studies, we have developed a new strategy for preparing Tb(III) SMMs. Our work shows that the SMM properties can be fine-tuned by introducing weak intermolecular magnetic interactions in a controlled SMM spatial arrangement.
Schwengner, R; Tsoneva, N; Benouaret, N; Beyer, R; Erhard, M; Grosse, E; Junghans, A R; Klug, J; Kosev, K; Lenske, H; Nair, C; Schilling, K D; Wagner, A
2008-01-01
The dipole response of the N=50 nucleus 90Zr was studied in photon-scattering experiments at the electron linear accelerator ELBE with bremsstrahlung produced at kinetic electron energies of 7.9, 9.0, and 13.2 MeV. We identified 189 levels up to an excitation energy of 12.9 MeV. Statistical methods were applied to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. In this way we derived the photoabsorption cross section up to the neutron-separation energy. This cross section matches well the photoabsorption cross section obtained from (gamma,n) data and thus provides information about the extension of the dipole-strength distribution toward energies below the neutron-separation energy. An enhancement of E1 strength has been found in the range of 6 MeV to 11 MeV. Calculations within the framework of the quasiparticle-phonon model ascribe this strength to a vibration of the excessive neutrons against the N = Z neutron-proton c...
Extension of CAVS coarse-grained model to phospholipid membranes: The importance of electrostatics.
Shen, Hujun; Deng, Mingsen; Zhang, Yachao
2017-05-15
It is evident from experiment that electrostatic potential (or dipole potential) is positive inside PC or PE lipid bilayers in the absence of ions. MARTINI coarse-grained (CG) model, which has been widely used in simulating physical properties of lipid bilayers, fails to reproduce the positive value for the dipole potential in the membrane interior. Although the total dipole potential can be correctly described by the BMW/MARTINI model, the contribution from the ester dipoles, playing a nontrivial role in the electrostatic potential across lipid membranes, is neglected by this hybrid approach. In the ELBA CG model, the role of the ester dipoles is considered, but it is overweighed because various atomistic models have consistently shown that water is actually the leading contributor of dipole potential. Here, we present a CG approach by combining the BMW-like water model (namely CAVS model) with the ELBA-like lipid model proposed in this work. Our CG model was designed not only to correctly reproduce the positive values for the dipole potential inside PC and PE lipid bilayers but also to properly balance the individual contributions from the ester dipoles and water, surmounting the limitations of current CG models in the calculations of dipole potential. © 2017 Wiley Periodicals, Inc.
Synchronization of magnetic dipole rotation in an ac magnetic field
Energy Technology Data Exchange (ETDEWEB)
Belovs, M; Cebers, A, E-mail: aceb@tesla.sal.lv [University of Latvia, Zellu-8, Riga, LV-1002 (Latvia)
2011-07-22
The synchronization of the rotation of magnetic dipoles due to weak dipolar interactions is studied. The set of equations is analyzed by the time averaging technique. It is found that dipoles synchronously oscillate at low applied fields and rotate synchronously at large applied fields. The mean angular velocity of synchronous rotation increases with the field strength and reaches a constant value equal to the angular frequency of the field above the critical value of the field strength. The critical value of the field strength above which the synchronous rotation takes place can be calculated from dimensionless parameters using a model derived from first principles by others. The values thus obtained are in good agreement with the values we obtain from a numerical simulation. Thus, we may conclude that the liquid flow observed in these systems may be caused by synchronized rotations of the dipoles.
Dipole polarizabilities of medium-sized gold clusters
Wang, Jinlan; Yang, Mingli; Jellinek, Julius; Wang, Guanghou
2006-08-01
The dipole polarizabilities of two families of low-lying structures, cage, and space filling, of the medium-sized AuN (N=32,38,44,50,56) clusters are studied using gradient-corrected density functional theory and finite field method. Both dipole moments and polarizabilities exhibit clear shape-dependent features and the cage structures have systematically smaller dipole moments and larger polarizabilities than the space-filling isomers. The mean polarizability per atom increases with cluster size for the cage structures, but it decreases slowly and tends to approach a constant for the space-filling structures. A linearly correlation between polarizability and cluster volume is noted, complying with the jellium model prediction for spherical metal clusters. The electronic effects including HOMO-LUMO gap and ionization energy on polarizabilities are also explored. The geometric effects play a dominant role on the determination of the polarizability of the cluster over the electronic effects.
Plasmonic interferometry: probing launching dipoles in scanning-probe plasmonics
Mollet, O; Genet, C; Huant, S; Drezet, A
2014-01-01
We develop a semi-analytical method for analyzing surface plasmon interferometry using near-field scanning optical sources. We compare our approach to Young double hole interferometry experiments using scanning tunneling microscope (STM) discussed in the literature and realize experiments with an aperture near-field scanning optical microscope (NSOM) source positioned near a ring like aperture slit milled in a thick gold film. In both cases the agreement between experiments and model is very good. We emphasize the role of dipole orientations and discuss the role of magnetic versus electric dipole contributions to the imaging process as well as the directionality of the effective dipoles associated with the various optical and plasmonic sources.
Forward and inverse problems of EEG dipole localization.
Musha, T; Okamoto, Y
1999-01-01
Mathematical procedures are discussed in detail of numerical solutions for obtaining scalp potentials from the electric sources. The finite-element method for an inhomogeneous volume conductor, the boundary-element method for a compartment model, and their hybrid for more general cases are discussed. Construction of the head model and typical estimation of electric conductivity of the compartment model is described, which can reduce errors in estimated dipole location caused by incorrect head geometry. The concept of reciprocity is explained, which is applied to understanding a relation between the electrode configuration and its sensitivity for various source conditions. Typical techniques for solving the inverse problem are reviewed for discrete source models. Methods of estimating accuracy of the dipole location in the presence of noise are discussed, together with some numerical examples. The dipolarity is a goodness-of-fit of the dipole approximation, and lowering of the dipolarity is related to inhomogeneous neuronal activity in the cortex. Finally, a criterion of determining the optimal number of model parameters is given in terms of AIC (Akaike Information Criterion), which is applied to decide the most probable number of equivalent dipoles.
Fine structure of the pygmy dipole resonance in (136)Xe.
Savran, D; Fritzsche, M; Hasper, J; Lindenberg, K; Müller, S; Ponomarev, V Yu; Sonnabend, K; Zilges, A
2008-06-13
The photoresponse of the semimagic N=82 nucleus (136)Xe was measured up to the neutron separation energy S(n) using the (gamma, gamma') reaction. A concentration of strong dipole excitations is observed well below S(n) showing a fragmented resonancelike structure. Microscopic calculations in the quasiparticle phonon model including complex configurations of up to three phonons agree well with the experimental data in the total integrated strength, in the shape and the fragmentation of the resonance, which allows us to draw conclusions on the damping mechanism of the pygmy dipole resonance.
The solition properties of dipole domains in superlattices
Institute of Scientific and Technical Information of China (English)
张启义; 田强
2002-01-01
The formation and propagation of dipole domains in superlattices are studied both by the modified discrete drift model and by the nonlinear schroedinger equation,the spatiotemporal distribution of the electric field and electron density are presented.The numerical results are compared with the soliton solutions of the nonlinear Schroedinger equation and analysed.It is shown that the numerical solutions agree with the soliton solutions of the nonlinear Schroedinger equation.The dipole electric-field domains in semiconductor superlattices have the properties of solitons.
Considering digits in a current model of numerical development
Roesch, Stephanie; Moeller, Korbinian
2015-01-01
Numerical cognition has long been considered the perfect example of abstract information processing. Nevertheless, there is accumulating evidence in recent years suggesting that the representation of number magnitude may not be entirely abstract but may present a specific case of embodied cognition rooted in the sensory and bodily experiences of early finger counting and calculating. However, so far none of the existing models of numerical development considers the influence of finger-based representations. Therefore, we make first suggestions on (i) how finger-based representations may be integrated into a current model of numerical development; and (ii) how they might corroborate the acquisition of basic numerical competencies at different development levels. PMID:25628559
Directory of Open Access Journals (Sweden)
Vernon Cooray
2016-11-01
Full Text Available The paper describes the net momentum transported by the transient electromagnetic radiation field of a long transient dipole in free space. In the dipole a current is initiated at one end and propagates towards the other end where it is absorbed. The results show that the net momentum transported by the radiation is directed along the axis of the dipole where the currents are propagating. In general, the net momentum P transported by the electromagnetic radiation of the dipole is less than the quantity U / c , where U is the total energy radiated by the dipole and c is the speed of light in free space. In the case of a Hertzian dipole, the net momentum transported by the radiation field is zero because of the spatial symmetry of the radiation field. As the effective wavelength of the current decreases with respect to the length of the dipole (or the duration of the current decreases with respect to the travel time of the current along the dipole, the net momentum transported by the radiation field becomes closer and closer to U / c , and for effective wavelengths which are much shorter than the length of the dipole, P ≈ U / c . The results show that when the condition P ≈ U / c is satisfied, the radiated fields satisfy the condition Δ t Δ U ≥ h / 4 π where Δ t is the duration of the radiation, Δ U is the uncertainty in the dissipated energy and h is the Plank constant.
A new dipole index of the salinity anomalies of the tropical Indian Ocean
Li, Junde; Liang, Chujin; Tang, Youmin; Dong, Changming; Chen, Dake; Liu, Xiaohui; Jin, Weifang
2016-01-01
With the increased interest in studying the sea surface salinity anomaly (SSSA) of the tropical Indian Ocean during the Indian Ocean Dipole (IOD), an index describing the dipole variability of the SSSA has been pursued recently. In this study, we first use a regional ocean model with a high spatial resolution to produce a high-quality salinity simulation during the period from 1982 to 2014, from which the SSSA dipole structure is identified for boreal autumn. On this basis, by further analysing the observed data, we define a dipole index of the SSSA between the central equatorial Indian Ocean (CEIO: 70°E-90°E, 5°S-5°N) and the region off the Sumatra-Java coast (SJC: 100°E-110°E, 13°S-3°S). Compared with previous SSSA dipole indices, this index has advantages in detecting the dipole signals and in characterizing their relationship to the sea surface temperature anomaly (SSTA) dipole variability. Finally, the mechanism of the SSSA dipole is investigated by dynamical diagnosis. It is found that anomalous zonal advection dominates the SSSA in the CEIO region, whereas the SSSA in the SJC region are mainly influenced by the anomalous surface freshwater flux. This SSSA dipole provides a positive feedback to the formation of the IOD events. PMID:27052319
A new dipole index of the salinity anomalies of the tropical Indian Ocean
Li, Junde; Liang, Chujin; Tang, Youmin; Dong, Changming; Chen, Dake; Liu, Xiaohui; Jin, Weifang
2016-04-01
With the increased interest in studying the sea surface salinity anomaly (SSSA) of the tropical Indian Ocean during the Indian Ocean Dipole (IOD), an index describing the dipole variability of the SSSA has been pursued recently. In this study, we first use a regional ocean model with a high spatial resolution to produce a high-quality salinity simulation during the period from 1982 to 2014, from which the SSSA dipole structure is identified for boreal autumn. On this basis, by further analysing the observed data, we define a dipole index of the SSSA between the central equatorial Indian Ocean (CEIO: 70°E-90°E, 5°S-5°N) and the region off the Sumatra-Java coast (SJC: 100°E-110°E, 13°S-3°S). Compared with previous SSSA dipole indices, this index has advantages in detecting the dipole signals and in characterizing their relationship to the sea surface temperature anomaly (SSTA) dipole variability. Finally, the mechanism of the SSSA dipole is investigated by dynamical diagnosis. It is found that anomalous zonal advection dominates the SSSA in the CEIO region, whereas the SSSA in the SJC region are mainly influenced by the anomalous surface freshwater flux. This SSSA dipole provides a positive feedback to the formation of the IOD events.
Pulsar Magnetospheres: Beyond the Flat Spacetime Dipole
Gralla, Samuel E; Philippov, Alexander
2016-01-01
Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields may have a significant nondipolar component. We introduce a general analytical method for studying the axisymmetric force-free magnetosphere of a slowly-rotating star of arbitrary magnetic field, mass, radius and moment of inertia, including all the effects of general relativity. We confirm that spacelike current is generically present in the polar caps (suggesting a pair production region), irrespective of the stellar magnetic field. We show that general relativity introduces a ~60% correction to the formula for the dipolar component of the surface magnetic field inferred from spindown. Finally, we show that the location and size of the polar caps can be modified dramatically by even modestly strong higher moments. This can affect emission processes occurring near the star ...
Collective Dipole-Dipole Interactions in an Atomic Array
Sutherland, R T
2016-01-01
The coherent dipole-dipole interactions of atoms in an atomic array are studied. It is found that the excitation probability of an atom in an array parallel to the direction of laser propagation ($\\boldsymbol{\\hat{k}}$) will either grow or decay logarithmically along $\\boldsymbol{\\hat{k}}$, depending on the detuning of the laser. The symmetry of the system for atomic separations of $\\delta r = j\\lambda/2$, where $j$ is an integer, causes the excitation distribution and scattered radiation to abruptly become symmetric about the center of the array. For atomic separations of $\\delta r < \\lambda/2$, the appearance of a collection of extremely subradiant states ($\\Gamma\\sim 0$), disrupts the described trend. In order to interpret the results from a finite array of atoms, a band structure calculation in the $N\\rightarrow \\infty$ limit is conducted where the decay rates and the Collective Lamb Shifts of the eigenmodes along the Brillouin zone are shown. Finally, the band structure of an array strongly affects it...
The sign of the dipole-dipole potential by axion exchange
Daido, Ryuji; Takahashi, Fuminobu
2017-09-01
We calculate a dipole-dipole potential between fermions mediated by a light pseudoscalar, axion, paying a particular attention to the overall sign. While the sign of the potential is physical and important for experiments to discover or constrain the axion coupling to fermions, there is often a sign error in the literature. The purpose of this short note is to clarify the sign issue of the axion-mediated dipole-dipole potential. As a by-product, we find a sign change of the dipole-dipole potenital due to the different spin of the mediating particle.
Diffraction of sound from a dipole source near to a barrier or an impedance discontinuity.
Buret, Marc; Li, Kai Ming; Attenborough, Keith
2003-05-01
Pierce's formulation for the diffraction of spherical waves by a hard wedge has been extended to the case of the sound field due to a dipole source. The same approach is also used to extend a semiempirical model for sound propagation above an impedance discontinuity due to a dipole source. The resulting formulas have been validated by comparing their numerical solutions with that computed by summing the sound fields due to two closely spaced monopole sources of equal magnitude but opposite in phase. These new formulations are then used to develop a simple model for calculating the dipole sound field diffracted by a barrier above an impedance ground. Applications of these models relate to transportation noise prediction, particularly railway noise abatement, for which dipole sources are commonly used. The numerical predictions have been found to compare reasonably well with indoor measurements using piezoceramic transducers as dipole sources.
High resolution modelling of the North Icelandic Irminger Current (NIIC
Directory of Open Access Journals (Sweden)
K. Logemann
2006-01-01
Full Text Available The northward inflow of Atlantic Water through Denmark Strait – the North Icelandic Irminger Current (NIIC – is simulated with a numerical model of the North Atlantic and Arctic Ocean. The model uses the technique of adaptive grid refinement which allows a high spatial resolution (1 km horizontal, 10 m vertical around Iceland. The model is used to assess time and space variability of volume and heat fluxes for the years 1997–2003. Passive tracers are applied to study origin and composition of NIIC water masses. The NIIC originates from two sources: the Irminger Current, flowing as part of the sub-polar gyre in 100–500 m depth along the Reykjanes Ridge and the shallow Icelandic coastal current, flowing north-westward on the south-west Icelandic shelf. The ratio of volume flux between the deep and shallow branch is around 2:1. The NIIC continues as a warm and saline branch northward through Denmark Strait where it entrains large amounts of polar water due to the collision with the southward flowing East Greenland Current. After passing Denmark Strait, the NIIC follows the coast line eastward being an important heat source for north Icelandic waters. At least 60% of the temporal temperature variability of north Icelandic waters is caused by the NIIC. The NIIC volume and heat transport is highly variable and depends strongly on the wind field north-east of Denmark Strait. Daily means can change from 1 Sv eastward to 2 Sv westward within a few days. Highest monthly mean transport rates occur in summer when winds from north are weak, whereas the volume flux is reduced by around 50% in winter. Summer heat flux rates can be even three times higher than in winter. The simulation also shows variability on the interannual scale. In particular weak winds from north during winter 2002/2003 combined with mild weather conditions south of Iceland led to anomalous high NIIC volume (+40% and heat flux (+60% rates. In this period, simulated north Icelandic
Islamic Theoretical Intertemporal Model of the Current Account
Directory of Open Access Journals (Sweden)
Hassan Belkacem Ghassan
2016-06-01
Full Text Available This paper aims to develop an Islamic intertemporal model of the current account based on the prevailing theoretical and empirical literature of PVMCA (Obstfeld and Rogoff, 1996, Cerrato et al., 2014. The proposed model is based on the budget constraint of the present and future consumption, which depends on the obligatory Zakat from the income and assets, the return rate on the owned assets, the inheritance linking previous to subsequent generation. Using logarithmic utility function, featured by a unitary elasticity of intertemporal substitution and a unitary coefficient of relative risk aversion, we show through Euler equation of consumption that there is an inverse relationship between consumption growth from the last age to the first one and the Zakat rate on assets. The outcomes of this result are that the Zakat on assets disciplines the consumer to have more rationality in consumption, and allows additional marginal assets for future generations. By assuming a unitary subjective discount rate, we indicate that the more the return rate on assets is high, the more the consumption growth between today and tomorrow will be fast. Through the budget constraint, if Zakat rate on the Zakatable assets is greater than Zakat rate on income, this leads to a relative expansion in private consumption of the wealthy group. Besides, we point out that an increase in return rate on assets, can drive to increasing or decreasing current consumption, because the substitution and income effects work in opposite ways.
A Catapult (Slingshot) Current Sheet Relaxation Model for Substorm Triggering
Machida, S.; Miyashita, Y.; Ieda, A.
2010-12-01
Based on the results of our superposed epoch analysis of Geotail data, we have proposed a catapult (slingshot) current sheet relaxation model in which earthward flows are produced in the central plasma sheet (CPS) due to the catapult (slingshot) current sheet relaxation, together with the rapid enhancement of Poynting flux toward the CPS in the lobe around X ~ -15 Re about 4 min before the substrom onset. These earthward flows are characterized by plasma pressure decrease and large amplitude magnetic field fluctuations. When these flows reach X ~ 12Re in the magnetotail, they give significant disturbances to the inner magnetosphere to initiate some instability such as a ballooning instability or other instabilities, and the substorm starts in the inner magnetosphere. The occurrence of the magnetic reconnection is a natural consequence of the initial convective earthward flows, because the relaxation of a highly stretched catapult current sheet produces a very thin current at its tailward edge being surrounded by intense magnetic fields which were formerly the off-equatorial lobe magnetic fields. Recently, Nishimura et al. [2010] reported that the substorm onset begins when faint poleward discrete arcs collide with equatorward quiet arcs. The region of earthward convective flows correlatively moves earthward prior to the onset. Thus, this region of the earthward convective flows seems to correspond to the faint poleward discrete arcs. Interestingly, our statistical analysis shows that the earthward convective flows are not produced by the magnetic reconnection, but they are attributed to the dominance of the earthward JxB force over the tailward pressure associated with the progress of the plasma sheet thinning.
Electric dipole moments: A global analysis
Chupp, Timothy; Ramsey-Musolf, Michael
2015-03-01
We perform a global analysis of searches for the permanent electric dipole moments (EDMs) of the neutron, neutral atoms, and molecules in terms of six leptonic, semileptonic, and nonleptonic interactions involving photons, electrons, pions, and nucleons. By translating the results into fundamental charge-conjugation-parity symmetry (CP) violating effective interactions through dimension six involving standard model particles, we obtain rough lower bounds on the scale of beyond the standard model CP-violating interactions ranging from 1.5 TeV for the electron EDM to 1300 TeV for the nuclear spin-independent electron-quark interaction. We show that planned future measurements involving systems or combinations of systems with complementary sensitivities to the low-energy parameters may extend the mass reach by an order of magnitude or more.
Near-Field Magnetic Dipole Moment Analysis
Harris, Patrick K.
2003-01-01
This paper describes the data analysis technique used for magnetic testing at the NASA Goddard Space Flight Center (GSFC). Excellent results have been obtained using this technique to convert a spacecraft s measured magnetic field data into its respective magnetic dipole moment model. The model is most accurate with the earth s geomagnetic field cancelled in a spherical region bounded by the measurement magnetometers with a minimum radius large enough to enclose the magnetic source. Considerably enhanced spacecraft magnetic testing is offered by using this technique in conjunction with a computer-controlled magnetic field measurement system. Such a system, with real-time magnetic field display capabilities, has been incorporated into other existing magnetic measurement facilities and is also used at remote locations where transport to a magnetics test facility is impractical.
Naturalness Bounds on Dipole Moments from New Physics
Akama, K; Katsuura, K; Akama, Keiichi; Hattori, Takashi; Katsuura, Kazuo
2002-01-01
Assuming naturalness that the quantum corrections to the mass should not exceed the order of the observed mass, we derive and apply model-independent bounds on the anomalous magnetic moments and electric dipole moments of leptons and quarks due to new physics.
Thermal pairing and giant dipole resonance in highly excited nuclei
Dang, Nguyen Dinh
2014-01-01
Recent results are reported showing the effects of thermal pairing in highly excited nuclei. It is demonstrated that thermal pairing included in the phonon damping model (PDM) is responsible for the nearly constant width of the giant dipole resonance (GDR) at low temperature $T $ 170 MeV.
One vertex spin-foams with the Dipole Cosmology boundary
Kisielowski, Marcin; Puchta, Jacek
2012-01-01
We find all the spin-foams contributing in the first order of the vertex expansion to the transition amplitude of the Bianchi-Rovelli-Vidotto Dipole Cosmology model. Our algorithm is general and provides spin-foams of arbitrarily given, fixed: boundary and, respectively, a number of internal vertices. We use the recently introduced Operator Spin-Network Diagrams framework.
Thermo-magneto coupling in a dipole plasma
Yoshida, Z; Morikawa, J; Saitoh, H
2012-01-01
On a dipole plasma, we observe the generation of magnetic moment, as the movement of the levitating magnet-plasma compound, in response to electron-cyclotron heating and the increase of $\\beta$ (magnetically-confined thermal energy). We formulate a thermodynamic model with interpreting heating as injection of microscopic magnetic moment; the corresponding chemical potential is the ambient magnetic field.
Permanent Electric Dipole Moment Search in 129Xe
Grasdijk, Jan; Bluemler, P.; Almendinger, F.; Heil, Werner; Jungmann, Klaus-Peter; Karpuk, S.; Krause, Hans-Joachim; Offenhaeuser, Andreas; Repetto, M.; Schmidt, Ulrich; Sobolev, Y.; Willmann, Lorenz; Zimmer, Stefan
2017-01-01
A permanent electric dipole moment (EDM) implies breakdown of P (parity) and T (time reversal) symmetries. Provided CPT holds, this implies CP violation. Observation of an EDM at achievable experimental sensitivity would provide unambiguous evidence for physics beyond the Standard Model and limits
Black rings with fourth dipole cause less hair loss
Chowdhury, B.D.
2012-01-01
An example of entropy enigma with a controlled CFT dual was recently studied in [1]. The enigmatic bulk configurations, considered within the STU model, can be mapped under spectral flow into black rings with three monopole and dipole charges. Even though the bulk and CFT configurations existed in t
Jiang, Shidong; Xu, Minzhong
2005-01-01
The analytical solutions for the general-four-wave-mixing hyperpolarizabilities $\\chi^{(3)}(-(w_1+w_2+w_3);w_1,w_2,w_3)$ on infinite chains under both Su-Shrieffer-Heeger and Takayama-Lin-Liu-Maki models of trans-polyacetylene are obtained through the scheme of dipole-dipole correlation. Analytical expressions of DC Kerr effect $\\chi^{(3)}(-w;0,0,w)$, DC-induced second harmonic generation $\\chi^{(3)}(-2w;0,w,w)$, optical Kerr effect $\\chi^{(3)}(-w;w,-w,w)$ and DC-electric-field-induced optica...
Tsunami-HySEA model validation for tsunami current predictions
Macías, Jorge; Castro, Manuel J.; González-Vida, José Manuel; Ortega, Sergio
2016-04-01
Model ability to compute and predict tsunami flow velocities is of importance in risk assessment and hazard mitigation. Substantial damage can be produced by high velocity flows, particularly in harbors and bays, even when the wave height is small. Besides, an accurate simulation of tsunami flow velocities and accelerations is fundamental for advancing in the study of tsunami sediment transport. These considerations made the National Tsunami Hazard Mitigation Program (NTHMP) proposing a benchmark exercise focussed on modeling and simulating tsunami currents. Until recently, few direct measurements of tsunami velocities were available to compare and to validate model results. After Tohoku 2011 many current meters measurement were made, mainly in harbors and channels. In this work we present a part of the contribution made by the EDANYA group from the University of Malaga to the NTHMP workshop organized at Portland (USA), 9-10 of February 2015. We have selected three out of the five proposed benchmark problems. Two of them consist in real observed data from the Tohoku 2011 event, one at Hilo Habour (Hawaii) and the other at Tauranga Bay (New Zealand). The third one consists in laboratory experimental data for the inundation of Seaside City in Oregon. Acknowledgements: This research has been partially supported by the Junta de Andalucía research project TESELA (P11-RNM7069) and the Spanish Government Research project DAIFLUID (MTM2012-38383-C02-01) and Universidad de Málaga, Campus de Excelencia Andalucía TECH. The GPU and multi-GPU computations were performed at the Unit of Numerical Methods (UNM) of the Research Support Central Services (SCAI) of the University of Malaga.
Modelling ac ripple currents in HTS coated conductors
Xu, Zhihan; Grilli, Francesco
2015-10-01
Dc transmission using high temperature superconducting (HTS) coated conductors (CCs) offers a promising solution to the globally growing demand for effective, reliable and economic transmission of green energy up to the gigawatt level over very long distances. The credible estimation of the losses and thereby the heat dissipation involved, where ac ripples (introduced in rectification/ac-dc conversion) are viewed as a potential source of notable contribution, is highly essential for the rational design of practical HTS dc transmission cables and corresponding cryogenic systems to fulfil this demand. Here we report a targeted modelling study into the ac losses in a HTS CC subject to dc and ac ripple currents simultaneously, by solving Maxwell’s equations using the finite element method (FEM) in the commercial software package COMSOL. It is observed that the instantaneous loss exhibits only one peak per cycle in the HTS CC subject to sinusoidal ripples, given that the amplitude of the ac ripples is smaller than approximately 20% of that of the dc current. This is a distinct contrast to the usual observation of two peaks per cycle in a HTS CC subject to ac currents only. The unique mechanism is also revealed, which is directly associated with the finding that, around any local minima of the applied ac ripples, the critical state of -J c is never reached at the edges of the HTS CC, as it should be according to the Bean model. When running further into the longer term, it is discovered that the ac ripple loss of the HTS CC in full-wave rectification decays monotonically, at a speed which is found to be insensitive to the frequency of the applied ripples within our targeted situations, to a relatively low level of approximately 1.38 × 10-4 W m-1 in around 1.7 s. Comparison between this level and other typical loss contributions in a HTS dc cable implies that ac ripple currents in HTS CCs should only be considered as a minor source of dissipation in superconducting dc
LOG PERIODIC DIPOLE ARRAY WITH PARASITIC ELEMENTS
The design and measured characteristics of dipole and monopole versions of a log periodic array with parasitic elements are discussed. In a dipole...array with parasitic elements, these elements are used in place of every alternate dipole, thereby eliminating the need of a twisted feed arrangement...for the elements to obtain log periodic performance of the anntenna. This design with parasitic elements lends itself to a monopole version of the
Shigella vaccine development: prospective animal models and current status.
Kim, Yeon-Jeong; Yeo, Sang-Gu; Park, Jae-Hak; Ko, Hyun-Jeong
2013-01-01
Shigella was first discovered in 1897 and is a major causative agent of dysenteric diarrhea. The number of affected patients has decreased globally because of improved sanitary conditions; however, Shigella still causes serious problems in many subjects, including young children and the elderly, especially in developing countries. Although antibiotics may be effective, a vaccine would be the most powerful solution to combat shigellosis because of the emergence of drug-resistant strains. However, the development of a vaccine is hampered by several problems. First, there is no suitable animal model that can replace human-based studies for the investigation of the in vivo mechanisms of Shigella vaccines. Mouse, guinea pig, rat, rabbit, and nonhuman primates could be used as models for shigellosis, but they do not represent human shigellosis and each has its own weaknesses. However, a recent murine model based on peritoneal infection with virulent S. flexneri 2a is promising. Moreover, although the inflammatory responses and mechanisms such as pathogenassociated molecular patterns and danger-associated molecular patterns have been studied, the pathology and immunology of Shigella are still not clearly defined. Despite these obstacles, many vaccine candidates have been developed, including live attenuated, killed whole cells, conjugated, and subunit vaccines. The development of Shigella vaccines also demands considerations of the cost, routes of administration, ease of storage (stability), cross-reactivity, safety, and immunogenicity. The main aim of this review is to provide a detailed introduction to the many promising vaccine candidates and animal models currently available, including the newly developed mouse model.
Lessons from the Current Japanese Triple Helix Model
Directory of Open Access Journals (Sweden)
Mitsuaki Hosono
2012-12-01
Full Text Available Since mid-1990s, the Japanese government has encouraged university-industry collaboration to foster innovations for economic growth. Learning from the American licensing model of technology transfer, Japanese Bay-Dole Act and TLO (Technology Licensing Organization Act were enacted in late 1990s. In addition, the corporatization of Japanese National Universities (JNUs in 2004 spurred their technology-transfer activities to obtain external funds. As a result, more than 50 TLOs has been established since FY1998, and also the number of patent application and licensed patents were increased at JUNs rapidly after FY2004. However, the licensing income has been stayed poor and some of TLOs were abolished. There are few evidences that the introduction of licensing model of technology transfer into Japan could contribute to innovation properly. Therefore, this study will try to clarify if licensing model of technology transfer work in Japan by analyzing the Japanese National University (JNU patent. There are 20,485 applied patent, which invented by JNU’s researcher(s from FY2004 to 2007. 38% of them were applied by solely by JNUs and 52% were by JNU and Private Firms etc. In the Japanese Patent Act, jointly applied patents are not licensed to the third party without the consent of co-applicant(s. Hence, more than half of the patent invented by JNU researchers is not basically used for patent licensing. Consequently, JNUs and TLOs face difficulties in patent licensing under the current Patent Act.
Current Capabilities of the Fuel Performance Modeling Code PARFUME
Energy Technology Data Exchange (ETDEWEB)
G. K. Miller; D. A. Petti; J. T. Maki; D. L. Knudson
2004-09-01
The success of gas reactors depends upon the safety and quality of the coated particle fuel. A fuel performance modeling code (called PARFUME), which simulates the mechanical and physico-chemical behavior of fuel particles during irradiation, is under development at the Idaho National Engineering and Environmental Laboratory. Among current capabilities in the code are: 1) various options for calculating CO production and fission product gas release, 2) a thermal model that calculates a time-dependent temperature profile through a pebble bed sphere or a prismatic block core, as well as through the layers of each analyzed particle, 3) simulation of multi-dimensional particle behavior associated with cracking in the IPyC layer, partial debonding of the IPyC from the SiC, particle asphericity, kernel migration, and thinning of the SiC caused by interaction of fission products with the SiC, 4) two independent methods for determining particle failure probabilities, 5) a model for calculating release-to-birth (R/B) ratios of gaseous fission products, that accounts for particle failures and uranium contamination in the fuel matrix, and 6) the evaluation of an accident condition, where a particle experiences a sudden change in temperature following a period of normal irradiation. This paper presents an overview of the code.
The Inverse Problem for the Dipole Field
Epp, V
2015-01-01
The Inverse problem for an electromagnetic field produced by a dipole is solved. It is assumed that the field of an arbitrary changing dipole is known. Obtained formulae allow calculation of the position and dynamics of the dipole which produces the measured field. The derived results can be used in investigations on radiative process in solids caused by changing of the charge distribution. For example, generation of the electromagnetic field caused by oscillations of atoms or electron gas at the trace of a particle channeling in a crystal, or fields arising at solids cracking or dislocation formation -- in any case when one is interested in the details of the dipole field source.
Slice of the LHC prototype beam tubes in dipole magnet
1995-01-01
A slice of the LHC accelerator prototype beam tubes surrounded by magnets. The LHC will accelerate two proton beams in opposite directions. The high bending and accelerating fields needed can only be reached using superconductors. At very low temperatures superconductors have no electrical resistance and therefore no power loss. The LHC will be the largest superconducting installation ever built, a unique challenge for CERN and its industrial partners. About dipole magnets: There will be 1232 dipole magnets in the LHC, used to guide the particles around the 27 km ring. Dipole magnets must have an extremely uniform field, which means the current flowing in the coils has to be very precisely controlled. Nowhere before has such precision been achieved at such high currents. The temperature is measured to five thousandths of a degree, the current to one part in a million. The current creating the magnetic field will pass through superconducting wires at up to 12 500 amps, about 30 000 times the current flowing ...
Prezeau, Gary
2016-01-01
A tool that can constrain, in minutes, beyond-the-standard-model parameters like electric dipole moments (EDM) down to a lower-bound $d_\\text{e}^{\\cal{N}}4.9\\cdot10^{-27}$ where $n_h$ is the ALP number density in the hair.
Critical state model with anisotropic critical current density
Bhagwat, K V; Ravikumar, G
2003-01-01
Analytical solutions of Bean's critical state model with critical current density J sub c being anisotropic are obtained for superconducting cylindrical samples of arbitrary cross section in a parallel geometry. We present a method for calculating the flux fronts and magnetization curves. Results are presented for cylinders with elliptical cross section with a specific form of the anisotropy. We find that over a certain range of the anisotropy parameter the flux fronts have shapes similar to those for an isotropic sample. However, in general, the presence of anisotropy significantly modifies the shape of the flux fronts. The field for full flux penetration also depends on the anisotropy parameter. The method is extended to the case of anisotropic J sub c that also depends on the local field B, and magnetization hysteresis curves are presented for typical values of the anisotropy parameter for the case of |J sub c | that decreases exponentially with |B|.
High voltage direct current modelling in optimal power flows
Energy Technology Data Exchange (ETDEWEB)
Ambriz-Perez, H. [Comision Federal de Electricidad, Mexico, Unidad de Ingenieria Especializada, Rio Rodano No. 14 - Piso 10, Sala 1002, Col. Cuauhtemoc, C.P. 06598, Mexico, D.F. (Mexico); Acha, E. [Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G128LT, Scotland (United Kingdom); Fuerte-Esquivel, C.R. [Faculty of Electrical Engineering, Universidad Michoacana de San Nicolas de Hidalgo, Morelia 58030, Michoacan (Mexico)
2008-03-15
Two-terminal high voltage direct current (HVDC) transmission links are in operation throughout the world. They are key elements in electrical power networks; their representation is oversimplified or ignored in most power system studies. This is particularly the case in Optima Power Flow (OPF) studies. Hence, an OPF program has been extended to incorporate HVDC links, taking due account of overlapping and power transfer control characteristics. This is a new development in Newton Optimal Power Flows, where the converter equations are included directly in the matrix W. The method is indeed a unified one since the solution vector is extended to accommodate the DC variables. The HVDC link model correctly takes into account the relevant DC limit variables. The impact of HVDC links on OPF studies is illustrated by numeric examples, which includes a 5-node system, the AEP 14-node and a 166-node system. (author)
Wall conditioning for ITER: Current experimental and modeling activities
Energy Technology Data Exchange (ETDEWEB)
Douai, D., E-mail: david.douai@cea.fr [CEA, IRFM, Association Euratom-CEA, 13108 St. Paul lez Durance (France); Kogut, D. [CEA, IRFM, Association Euratom-CEA, 13108 St. Paul lez Durance (France); Wauters, T. [LPP-ERM/KMS, Association Belgian State, 1000 Brussels (Belgium); Brezinsek, S. [FZJ, Institut für Energie- und Klimaforschung Plasmaphysik, 52441 Jülich (Germany); Hagelaar, G.J.M. [Laboratoire Plasma et Conversion d’Energie, UMR5213, Toulouse (France); Hong, S.H. [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Lomas, P.J. [CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Lyssoivan, A. [LPP-ERM/KMS, Association Belgian State, 1000 Brussels (Belgium); Nunes, I. [Associação EURATOM-IST, Instituto de Plasmas e Fusão Nuclear, 1049-001 Lisboa (Portugal); Pitts, R.A. [ITER International Organization, F-13067 St. Paul lez Durance (France); Rohde, V. [Max-Planck-Institut für Plasmaphysik, 85748 Garching (Germany); Vries, P.C. de [ITER International Organization, F-13067 St. Paul lez Durance (France)
2015-08-15
Wall conditioning will be required in ITER to control fuel and impurity recycling, as well as tritium (T) inventory. Analysis of conditioning cycle on the JET, with its ITER-Like Wall is presented, evidencing reduced need for wall cleaning in ITER compared to JET–CFC. Using a novel 2D multi-fluid model, current density during Glow Discharge Conditioning (GDC) on the in-vessel plasma-facing components (PFC) of ITER is predicted to approach the simple expectation of total anode current divided by wall surface area. Baking of the divertor to 350 °C should desorb the majority of the co-deposited T. ITER foresees the use of low temperature plasma based techniques compatible with the permanent toroidal magnetic field, such as Ion (ICWC) or Electron Cyclotron Wall Conditioning (ECWC), for tritium removal between ITER plasma pulses. Extrapolation of JET ICWC results to ITER indicates removal comparable to estimated T-retention in nominal ITER D:T shots, whereas GDC may be unattractive for that purpose.
Testing of a Single 11 T $Nb_3Sn$ Dipole Coil Using a Dipole Mirror Structure
Energy Technology Data Exchange (ETDEWEB)
Zlobin, Alexander [Fermilab; Andreev, Nicolai [Fermilab; Barzi, Emanuela [Fermilab; Chlachidze, Guram [Fermilab; Kashikhin, Vadim [Fermilab; Nobrega, Alfred [Fermilab; Novitski, Igor [Fermilab; Turrioni, Daniele [Fermilab; Karppinen, Mikko [CERN; Smekens, David [CERN
2014-07-01
FNAL and CERN are developing an 11 T Nb3Sn dipole suitable for installation in the LHC. To optimize coil design parameters and fabrication process and study coil performance, a series of 1 m long dipole coils is being fabricated. One of the short coils has been tested using a dipole mirror structure. This paper describes the dipole mirror magnetic and mechanical designs, and reports coil parameters and test results.
National Oceanic and Atmospheric Administration, Department of Commerce — The purpose of this project is to develop spatially discrete end-to-end models of the California Current LME, linking oceanography, biogeochemistry, food web...
Todesco, E; De Rijk, G; Rossi, L
2014-01-01
For the High Energy LHC, a study of a 33 TeV center of mass collider in the LHC tunnel, main dipoles of 20 T operational field are needed. In this paper we first review the conceptual design based on block coil proposed in the Malta workshop, addressing the issues related to coil fabrication and assembly. We then propose successive simplifications of this design, associating a cost estimate of the conductor. We then analyse a block layout for a 15 T magnet. Finally, we consider two layouts based on the D20 and HD2 short models built by LBL. A first analysis of the aspects related to protection of these challenging magnets is given.
Electric dipole moment enhancement factor of thallium
Porsev, Sergey; Safronova, Marianna; Kozlov, Mikhail
2012-06-01
A number of extensions of the standard model of particle physics predict electric dipole moments (EDM) of particles that may be observable with the present state-of-the art experiments. The EDMs arise from the violations of both parity and time-reversal invariance. The electron EDM is enhanced in certain atomic and molecular systems. One of the most stringent limits on the electron EDM de was obtained from the experiments with ^205Tl: decontroversy in the value of the EDM enhancement factor K in Tl. We have carried out several calculations by different high-precision methods, studied previously omitted corrections, as well as tested our methodology on other parity conserving quantities. We find the EDM enhancement factor of Tl to be equal to -573(20). This value is 20% larger than the recently published result of Nataraj et al. [PRL 106, 200403 (2011)] but agrees very well with several earlier results.
Current amplification models of sensorineurall and conductive hearing loss
Directory of Open Access Journals (Sweden)
Ostojić Sanja
2012-01-01
Full Text Available The main function of a hearing aid is to improve auditory and language abilities of hearing impaired users. The amplification model has to be adapted according to age, degree and type of hearing loss. The goal of this paper is to analyze the current amplification models of sensorineural and conductive hearing loss which can provide a high quality of speech perception and sounds at any degree of hearing loss. The BAHA is a surgically implantable system for treatment of conductive hearing loss that works through direct bone conduction. BAHA is used to help people with chronic ear infections, congenital external auditory canal atresia and single sided deafness who cannot benefit from conventional hearing aids. The last generation of hearing aid for sensorineural hearing loss is cochlear implant. Bimodal amplification improves binaural hearing. Hearing aids alone do not make listening easier in all situations. The things that can interfere with listening are background noises, distance from a sound and reverberation or echo. The device used most often today is the Frequency Modulated (FM system.
Modelling counter-current chromatography: a chemical engineering perspective.
Kostanian, A E
2002-10-11
In conventional chromatography, a solute is usually viewed to be longitudinally transported only in the mobile phase, remaining longitudinally motionless in the stationary phase. In counter-current chromatography, both phases undergo intense mixing in the variable force field of a coil planet centrifuge and longitudinal dispersion of matter in the stationary phase is not to be excluded. To take into account longitudinal mixing in both phases, a cell model of chromatographic process is proposed in which the number of perfectly mixed cells n is determined by the rates of mixing in stationary (Ds) and mobile (Dm) phases by the equation n = LF/(2ADc)/(1 + Sf(lambda - 1)) with A = K(D)D(S)/Dm (F, L, Ac and KD are the mobile phase flow-rate, column length, column cross-section and distribution ratio, respectively). This equation has been derived by comparing the discontinuous cell model with continuous diffusion assuming equilibrium conditions. Parameter determination and their relationships are discussed.
A geomagnetically induced current warning system: model development and validation
McKay, A.; Clarke, E.; Reay, S.; Thomson, A.
Geomagnetically Induced Currents (GIC), which can flow in technological systems at the Earth's surface, are a consequence of magnetic storms and Space Weather. A well-documented practical problem for the power transmission industry is that GIC can affect the lifetime and performance of transformers within the power grid. Operational mitigation is widely considered to be one of the best strategies to manage the Space Weather and GIC risk. Therefore in the UK a magnetic storm warning and GIC monitoring and analysis programme has been under development by the British Geological Survey and Scottish Power plc (the power grid operator for Central Scotland) since 1999. Under the auspices of the European Space Agency's service development activities BGS is developing the capability to meet two key user needs that have been identified. These needs are, firstly, the development of a near real-time solar wind shock/ geomagnetic storm warning, based on L1 solar wind data and, secondly, the development of an integrated surface geo-electric field and power grid network model that should allow prediction of GIC throughout the power grid in near real time. While the final goal is a `seamless package', the components of the package utilise diverse scientific techniques. We review progress to date with particular regard to the validation of the individual components of the package. The Scottish power grid response to the October 2003 magnetic storms is also discussed and model and validation data are presented.
Soft Dipole Modes of Neutron-Rich Nuclei
Csoto, A.; Gibson, B. F.; Afnan, I. R.
1996-10-01
We explore the open question of whether valance neutrons in ``halo nuclei'' can oscillate against the core to create a ``soft dipole'' mode. It has been suggested that such a dipole state would be situated at a few MeV of excitation energy, in contrast to usual dipole excitations at higher energies. The existence of a soft dipole mode, at least in ^11Li, appears to be supported by certain theoretical models and experimental data.footnote A. C. Hayes, Comments in Nuclear and Particle Physics 22, 27 (1996) However, this conclusion is based upon the behavior of specific observables at real energies. To clearly establish the existence of such resonant states, one should locate the corresponding complex poles of the S-matrix. We study ^6He and ^11Li in a three-body model based upon separable potentials that describe the known physics of the underlying two-body interactions. We solve the resulting Faddeev equations, continued into the complex energy plane, to search for the low lying excited states of these neutron-rich light nuclei.
A Crucial Dipole Test of the Expansion Center Universe
Lorenzi, Luciano
2011-01-01
The expansion center Universe gives a dipole anisotropy to the Hubble law, at any Hubble depth D. After a long series of successful dipole tests on the nearby Universe, using historic data sets of about half a century, and that carried out on 53 SCP SNe Ia ranging around the average redshift =0.5 (ECM paper VI: SAIt2004 in Milan), here is a crucial multiple dipole test at z bins centred on the mean =1.0, or Hubble depth D=c/H0, and based on data from SCP Union compilation (SCPU: Kowalski et al. 2008) and SCP Union2 (SCPU2: Amanullah et al. 2010), including those obtained within "The new wedge-shaped Hubble diagram of 398 SCP supernovae..." (ECM paper IX: SAIt2010 in Naples). Table 5abc lists data of two main samples, with 48 SCPU SNe Ia and 58 SCPU2 SNe Ia respectively. The confirmed dipole anisotropy, shown by 6 primary sample tests and by another 27 from 9 encapsulated z bins with D=DL/(1+z), gives a model independent result, in full accordance with the expansion center model. This means a maximum cz range ...
Dust Composition in Climate Models: Current Status and Prospects
Pérez García-Pando, C.; Miller, R. L.; Perlwitz, J. P.; Kok, J. F.; Scanza, R.; Mahowald, N. M.
2015-12-01
Mineral dust created by wind erosion of soil particles is the dominant aerosol by mass in the atmosphere. It exerts significant effects on radiative fluxes, clouds, ocean biogeochemistry, and human health. Models that predict the lifecycle of mineral dust aerosols generally assume a globally uniform mineral composition. However, this simplification limits our understanding of the role of dust in the Earth system, since the effects of dust strongly depend on the particles' physical and chemical properties, which vary with their mineral composition. Hence, not only a detailed understanding of the processes determining the dust emission flux is needed, but also information about its size dependent mineral composition. Determining the mineral composition of dust aerosols is complicated. The largest uncertainty derives from the current atlases of soil mineral composition. These atlases provide global estimates of soil mineral fractions, but they are based upon massive extrapolation of a limited number of soil samples assuming that mineral composition is related to soil type. This disregards the potentially large variability of soil properties within each defined soil type. In addition, the analysis of these soil samples is based on wet sieving, a technique that breaks the aggregates found in the undisturbed parent soil. During wind erosion, these aggregates are subject to partial fragmentation, which generates differences on the size distribution and composition between the undisturbed parent soil and the emitted dust aerosols. We review recent progress on the representation of the mineral and chemical composition of dust in climate models. We discuss extensions of brittle fragmentation theory to prescribe the emitted size-resolved dust composition, and we identify key processes and uncertainties based upon model simulations and an unprecedented compilation of observations.
Lessons from the Current Japanese Triple Helix Model
Directory of Open Access Journals (Sweden)
Mitsuaki Hosono
2013-01-01
Full Text Available Since mid-1990s, the Japanese government has encouraged university-industry collaboration to foster innovations for economic growth. Learning from the American licensing model of technology transfer, Japanese Bay-Dole Act and TLO (Technology Licensing Organization Act were enacted in late 1990s. In addition, the corporatization of Japanese National Universities (JNUs in 2004 spurred their technology-transfer activities to obtain external funds. As a result, more than 50 TLOs has been established since FY1998, and also the number of patent application and licensed patents were increased at JUNs rapidly after FY2004. However, the licensing income has been stayed poor and some of TLOs were abolished. There are few evidences that the introduction of licensing model of technology transfer into Japan could contribute to innovation properly. Therefore, this study will try to clarify if licensing model of technology transfer work in Japan by analyzing the Japanese National University (JNU patent. There are 20,485 applied patent, which invented by JNU’s researcher(s from FY2004 to 2007. 38% of them were applied by solely by JNUs and 52% were by JNU and Private Firms etc. In the Japanese Patent Act, jointly applied patents are not licensed to the third party without the consent of co-applicant(s. Hence, more than half of the patent invented by JNU researchers is not basically used for patent licensing. Consequently, JNUs and TLOs face difficulties in patent licensing under the current Patent Act. Keywords: Technology Transfer, TLO, University Patent, Japan
Final Report: Levitated Dipole Experiment
Energy Technology Data Exchange (ETDEWEB)
Kesner, Jay [Massachusetts Institute of Technology, Cambridge, MA (United States); Mauel, Michael [Columbia Univ., New York, NY (United States)
2013-03-10
Since the very first experiments with the LDX, research progress was rapid and significant. Initial experiments were conducted with the high-field superconducting coil suspended by three thin rods. These experiments produced long-pulse, quasi-steady-state microwave discharges, lasting more than 10 s, having peak beta values of 20% [Garnier et al., Physics of Plasmas, 13 (2006) 056111]. High- beta, near steady-state discharges have been maintained in LDX for more than 20 seconds, and this capability made LDX the longest pulse fusion confinement experiment operating in the U.S. fusion program. A significant measure of progress in the LDX research program was the routine investigation of plasma confinement with a magnetically-levitated dipole and the resulting observations of confinement improvement. In both supported and levitated configurations, detailed measurements were made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. High-temperature plasma was created by multi frequency electron cyclotron resonance heating at 2.45 GHz, 6.4 GHz, 10.5 GHz and 28 GHz allowing control of heating profiles. Depending upon neutral fueling rates, the LDX discharges contain a fraction of energetic electrons, with mean energies above 50 keV. Depending on whether or not the superconducting dipole was levitated or supported, the peak thermal electron temperature was estimated to exceed 500 eV and peak densities to approach 1e18 m^{-3}. We have found that levitation causes a strong inwards density pinch [Boxer et al., Nature Physics, 6 (2010) 207] and we have observed the central plasma density increase dramatically indicating a significant improvement in the confinement of a thermal plasma species.
Hare, V. J.; Gallet, Y.; Genevey, A.
2015-12-01
Current global geomagnetic field models suffer from strong bias towards Northern Hemisphere data. Absolute intensity measurements from the Southern Hemisphere are key to understanding the evolution of the field over the historical era, especially recent strengthening of non-dipole contributions, and the appearance of the South Atlantic Magnetic Anomaly (SAMA). I present the first archaeointensity data for locally-fired historical bricks from several well-dated sites (1660-2009 AD) in Cape Town, South Africa. These data constitute the first archaeomagnetic intensity variation curve for southern Africa for the past few centuries. The ages of the sites are tightly constrained by historical and archaeological considerations. Archaeointensity data obtained by the Thellier and Thellier method (modified by Coe), are corrected for both TRM anisotropy and cooling rate dependence of TRM acquisition. Analysis of magnetic mineralogy was performed to aid selection of fragments. Reliable archaeointensity determinations were obtained for 48 of 80 specimens, and 45 were retained in the final analysis. Intensity results vary from 24.3 ± 0.6 μT (modern brick) to 40.7 ± 0.8 μT (1660 AD), corresponding to Virtual Axial Dipole Moments (VADMs) between 6.1 ± 0.2 and 10.2 ± 0.2 נ1022 Am2. Results are generally not in agreement with current field models, but are coherent with other archaeomagnetic datasets from the Southern Hemisphere. The possible reasons for this are discussed, as well as implications for the historical evolution of the field.
Gravitational radiation from a rotating magnetic dipole
Hacyan, Shahen
2016-01-01
The gravitational radiation emitted by a rotating magnetic dipole is calculated. Formulas for the polarization amplitudes and the radiated power are obtained in closed forms, considering both the near and radiation zones of the dipole. For a neutron star, a comparison is made with other sources of gravitational and electromagnetic radiation.
Magnetic dipole oscillations and radiation damping
Stump, Daniel R.; Pollack, Gerald L.
1997-01-01
We consider the problem of radiation damping for a magnetic dipole oscillating in a magnetic field. An equation for the radiation reaction torque is derived, and the damping of the oscillations is described. Also discussed are runaway solutions for a rotating magnetic dipole moving under the influence of the reaction torque, with no external torque.
Experimental results on the Pygmy Dipole Resonance
Directory of Open Access Journals (Sweden)
Savran Deniz
2014-03-01
Full Text Available The so-called Pygmy Dipole Resonance, an additional structure of low-lying electric dipole strength, has attracted strong interest in the last years. Different experimental approaches have been used in the last decade in order to investigate this new interesting nuclear excitation mode. In this contribution an overview on the available experimental data is given.