Two-loop master integrals for γ*→3 jets: the planar topologies
International Nuclear Information System (INIS)
Gehrmann, T.; Remiddi, E.
2001-01-01
The calculation of the two-loop corrections to the three jet production rate and to event shapes in electron-positron annihilation requires the computation of a number of up to now unknown two-loop four-point master integrals with one off-shell and three on-shell legs. In this paper we compute those master integrals which correspond to planar topologies by solving differential equations in the external invariants which are fulfilled by the master integrals. We obtain the master integrals as expansions in ε=(4-d)/2, where d is the space-time dimension. The results are expressed in terms of newly introduced two-dimensional harmonic polylogarithms, whose properties are shortly discussed. For all two-dimensional harmonic polylogarithms appearing in the divergent parts of the integrals, expressions in terms of Nielsen's polylogarithms are given. The analytic continuation of our results to other kinematical situations is outlined
Two-loop QCD corrections to massless identical quark scattering
Energy Technology Data Exchange (ETDEWEB)
Anastasiou, C. E-mail: ch.anastasiou@durham.ac.uk; Glover, E.W.N. E-mail: e.w.n.glover@durham.ac.uk; Oleari, C. E-mail: oleari@pheno.physics.wisc.edu; Tejeda-Yeomans, M.E. E-mail: m.e.tejeda-yeomans@durham.ac.uk
2001-05-07
We present the two-loop virtual QCD corrections to the scattering of identical massless quarks, qq-bar{yields}qq-bar, in conventional dimensional regularisation and using the MS-bar scheme. The structure of the infrared divergences agrees with that predicted by Catani while expressions for the finite remainder are given for the qq-bar{yields}qq-bar and the qq{yields}qq (q-barq-bar{yields}q-barq-bar) scattering processes in terms of polylogarithms. The results presented here form a vital part of the next-to-next-to-leading order contribution to inclusive jet production in hadron colliders and will play a crucial role in improving the theoretical prediction for jet cross sections in hadron-hadron collisions.
Two-Loop Control of Redundant Manipulators: Analysis and Experiments on a 3-DOF Planar Arm
Directory of Open Access Journals (Sweden)
Israel Soto
2013-01-01
Full Text Available A redundant robot has more degrees of freedom (DOF than those required to accomplish a given motion task. This fact allows the possibility of achieving an additional task, such as avoidance of joint limits or singularities, besides the primary one. Different criteria have been proposed in the literature for the selection of such a secondary task. This paper first recalls some of those criteria and then proposes a two-loop scheme for the motion control of redundant robots. In order to validate the proposed scheme, some experiments are carried out in a direct-drive redundant planar arm which has been designed and built in our laboratory.
Two-loop planar master integrals for the production of off-shell vector bosons in hadron collisions
International Nuclear Information System (INIS)
Henn, Johannes M.; Melnikov, Kirill; Smirnov, Vladimir A.
2014-01-01
We describe the calculation of all planar master integrals that are needed for the computation of NNLO QCD corrections to the production of two off-shell vector bosons in hadron collisions. The most complicated representatives of integrals in this class are the two-loop four-point functions where two external lines are on the light-cone and two other external lines have different invariant masses. We compute these and other relevant integrals analytically using differential equations in external kinematic variables and express our results in terms of Goncharov polylogarithms. The case of two equal off-shellnesses, recently considered in ref. http://dx.doi.org/10.1007/JHEP08(2013)070, appears as a particular case of our general solution
Two-loop planar master integrals for Higgs →3 partons with full heavy-quark mass dependence
International Nuclear Information System (INIS)
Bonciani, Roberto; Duca, Vittorio Del; Frellesvig, Hjalte; Henn, Johannes M.; Moriello, Francesco; Smirnov, Vladimir A.
2016-01-01
We present the analytic computation of all the planar master integrals which contribute to the two-loop scattering amplitudes for Higgs→3 partons, with full heavy-quark mass dependence. These are relevant for the NNLO corrections to fully inclusive Higgs production and to the NLO corrections to Higgs production in association with a jet, in the full theory. The computation is performed using the differential equations method. Whenever possible, a basis of master integrals that are pure functions of uniform weight is used. The result is expressed in terms of one-fold integrals of polylogarithms and elementary functions up to transcendental weight four. Two integral sectors are expressed in terms of elliptic integrals. We show that by introducing a one-dimensional parametrization of the integrals the relevant second order differential equation can be readily solved, and the solution can be expressed to all orders of the dimensional regularization parameter in terms of iterated integrals over elliptic kernels. We express the result for the elliptic sectors in terms of two and three-fold iterated integrals, which we find suitable for numerical evaluations. This is the first time that four-point multiscale Feynman integrals have been computed in a fully analytic way in terms of elliptic integrals.
Two-loop corrections to Higgs production and decay in the MSSM
International Nuclear Information System (INIS)
Heinemeyer, S.; Weiglein, G.
2000-01-01
In the Minimal Supersymmetric Standard Model (MSSM) we incorporate the Higgs-boson propagator corrections, evaluated up to two-loop order, into the prediction of the cross sections for the Higgs boson production mechanism, e + e - → hZ, hA, and into the evaluation of Higgs decay rates and branching ratios, Γ(h → ff-bar) and BR(h → ff-bar) for f = b, τ. The propagator corrections consist of the full one-loop contribution, including the effects of non-vanishing external momentum, and at the two-loop level of the dominant corrections of O(αα s ) and further sub-dominant contributions. The results are supplemented with one-loop vertex and box corrections. The effects of the two-loop propagator corrections and of specific one-loop contributions are investigated in detail. Our results are compared with the result obtained within the renormalization group approach. Agreement within O(10%) is found for most parts of the MSSM parameter space
Dominant two-loop corrections to the MSSM finite temperature effective potential
International Nuclear Information System (INIS)
Espinosa, J.R.
1996-04-01
We show that two-loop corrections to the finite temperature effective potential in the MSSM can have a dramatic effect on the strength of the electroweak phase transition, making it more strongly first order. The change in the order parameter v/Tc can be as large as 75% of the one-loop daisy improved result. This effect can be decisive to widen the region in parameter space where erasure of the created baryons by sphaleron processes after the transition is suppressed and hence, where electroweak baryogenesis might be successful. We find an allowed region with tan β< or∼4.5 and a Higgs boson with standard couplings and mass below 80 GeV within the reach of LEP II. (orig.)
Two loop QCD corrections for the process pseudo-scalar Higgs → 3 partons
Banerjee, Pulak; Dhani, Prasanna K.; Ravindran, V.
2017-10-01
We present virtual contributions up to two loop level in perturbative Quantum Chromodynamic (QCD) to the decay of pseudo-scalar Higgs boson ( A) to three gluons ( g) and also to quark ( q), anti-quark ( \\overline{q} ) and a gluon. With appropriate crossing, they are well suited for predicting the differential distribution of A in association with a jet in hadron colliders up to next-to-next-to-leading order (NNLO) in strong coupling constant and also for the subsequent decay of A to hadrons. We use effective field theory approach to integrate out the top quarks in the heavy top limit. The resulting theory involves two pseudo-scalar composite operators describing the interaction of A with gluons as well as with quark and anti-quark. We perform our computation in dimensional regularisation and use minimal subtraction ( \\overline{MS} ) scheme to renormalise strong coupling constant as well as the composite operators. The ultraviolet (UV) finite amplitudes contain infrared (IR) divergences that are found to be in agreement with the predictions by Catani. For both the amplitudes namely A → ggg and A\\to q\\overline{q}g , the leading transcendental terms at one and two loops are found to be identical to those in a three point form factor (FF) of the half-BPS operator in N=4 Supersymmetric Yang Mills (SYM) theory when the QCD color factors are adjusted in a specific way. We present our results in terms of harmonic polylogs well suited for further numerical study.
Two-loop top and bottom Yukawa corrections to the Higgs-boson masses in the complex MSSM
Paßehr, Sebastian; Weiglein, Georg
2018-03-01
Results for the two-loop corrections to the Higgs-boson masses of the MSSM with complex parameters of O{( α _t^2+α _tα _b+α _b^2) } from the Yukawa sector in the gauge-less limit are presented. The corresponding self-energies and their renormalization have been obtained in the Feynman-diagrammatic approach. The impact of the new contributions on the Higgs spectrum is investigated. Furthermore, a comparison with an existing result in the limit of the MSSM with real parameters is carried out. The new results will be included in the public code FeynHiggs.
Two loop O(αsGFmt2) corrections to the fermionic decay rates of the standard-model Higgs boson
International Nuclear Information System (INIS)
Kniehl, B.A.
1994-05-01
Low- and intermediate mass Higgs bosons decay preferably into fermion pairs. The one-loop electroweak corrections to the respective decay rates are dominated by a flavour-independent term of O(G F m t 2 ). We calculate the two-loop gluon correction to this term. It turns out that this correction screens the leading high-m t behaviour of the one-loop result by roughly 10%. We also present the two-loop QCD correction to the contribution induced by a pair of fourth-generation quarks with arbitrary masses. As expected, the inclusion of the QCD correction considerably reduces the renormalization-scheme dependence of the prediction. (orig.)
On the two-loop corrections to the pole mass of the B quark in the gaugeless limit of the MSSM
International Nuclear Information System (INIS)
Bednyakov, A.V.; Kazakov, D.I.; )
2007-01-01
The result for the two-loop corrections to the pole mass of the b quark in the gaugeless limit of the MSSM is presented. In this limit it is assumed that the contribution from the electroweak gauge interactions is small. The result presented here differs from one obtained earlier, especially in some particular regions of the MSSM parameter space [ru
International Nuclear Information System (INIS)
Roiban, R.; Tseytlin, A. A.
2008-01-01
We consider folded (S,J) spinning strings in AdS 5 xS 5 (with one spin component in AdS 5 and a one in S 5 ) corresponding to the Tr(D S Φ J ) operators in the sl(2) sector of the N=4 super Yang-Mills theory in the special scaling limit in which both the string mass ∼√(λ)lnS and J are sent to infinity with their ratio fixed. Expanding in the parameter l=(J/√(λ)lnS) we compute the 2-loop string sigma-model correction to the string energy and show that it agrees with the expression proposed by Alday and Maldacena [J. High Energy Phys. 11 (2007) 019]. We suggest that a resummation of the logarithmic l 2 ln n l terms is necessary in order to establish an interpolation to the weakly coupled gauge-theory results. In the process, we set up a general framework for the calculation of higher loop corrections to the energy of multispin string configurations. In particular, we find that in addition to the direct 2-loop term in the string energy there is a contribution from lower loop order due to a finite 'renormalization' of the relation between the parameters of the classical solution and the fixed spins, i.e., the charges of the SO(2,4)xSO(6) symmetry.
Higgs Decay to Photons at Two Loops
International Nuclear Information System (INIS)
Fugel, F.
2007-01-01
The calculation of the two-loop corrections to the partial width of an intermediate-mass Higgs boson decaying into a pair of photons is reviewed. The main focus lies on the electroweak (EW) contributions. The sum of the EW corrections ranges from -4% to 0% for a Higgs mass between 100 GeV and 150 GeV, while the complete correction at two-loop order amounts to less than ± 1.5% in this regime. (author)
Two-Loop Scattering Amplitudes from the Riemann Sphere
Geyer, Yvonne; Monteiro, Ricardo; Tourkine, Piotr
2016-01-01
The scattering equations give striking formulae for massless scattering amplitudes at tree level and, as shown recently, at one loop. The progress at loop level was based on ambitwistor string theory, which naturally yields the scattering equations. We proposed that, for ambitwistor strings, the standard loop expansion in terms of the genus of the worldsheet is equivalent to an expansion in terms of nodes of a Riemann sphere, with the nodes carrying the loop momenta. In this paper, we show how to obtain two-loop scattering equations with the correct factorization properties. We adapt genus-two integrands from the ambitwistor string to the nodal Riemann sphere and show that these yield correct answers, by matching standard results for the four-point two-loop amplitudes of maximal supergravity and super-Yang-Mills theory. In the Yang-Mills case, this requires the loop analogue of the Parke-Taylor factor carrying the colour dependence, which includes non-planar contributions.
Master integrals for the NNLO virtual corrections to μe scattering in QED: the planar graphs
Mastrolia, Pierpaolo; Passera, Massimo; Primo, Amedeo; Schubert, Ulrich
2017-11-01
We evaluate the master integrals for the two-loop, planar box-diagrams contributing to the elastic scattering of muons and electrons at next-to-next-to leading-order in QED. We adopt the method of differential equations and the Magnus exponential series to determine a canonical set of integrals, finally expressed as a Taylor series around four space-time dimensions, with coefficients written as combination of generalised polylogarithms. The electron is treated as massless, while we retain full dependence on the muon mass. The considered integrals are also relevant for crossing-related processes, such as di-muon production at e + e --colliders, as well as for the QCD corrections to top-pair production at hadron colliders.
The gluon beam function at two loops
Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.
2014-08-01
The virtuality-dependent beam function is a universal ingredient in the resummation for observables probing the virtuality of incoming partons, including N -jettiness and beam thrust. We compute the gluon beam function at two-loop order. Together with our previous results for the two-loop quark beam function, this completes the full set of virtuality-dependent beam functions at next-to-next-to-leading order (NNLO). Our results are required to account for all collinear initial-state radiation effects on the N -jettiness event shape through N3LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N3LL order. Numerically, the NNLO matching corrections are important. They reduce the residual matching scale dependence in the resummed beam function by about a factor of two.
The gluon beam function at two loops
Energy Technology Data Exchange (ETDEWEB)
Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group
2014-05-15
The virtuality-dependent beam function is a universal ingredient in the resummation for observables probing the virtuality of incoming partons, including N-jettiness and beam thrust. We compute the gluon beam function at two-loop order. Together with our previous results for the two-loop quark beam function, this completes the full set of virtuality-dependent beam functions at next-to-next-to-leading order (NNLO). Our results are required to account for all collinear ISR effects to the N-jettiness event shape through N{sup 3}LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N{sup 3}LL order. Numerically, the NNLO matching corrections are important. They reduce the residual matching scale dependence in the resummed beam function by about a factor of two.
An Overview of Maximal Unitarity at Two Loops
Johansson, Henrik; Larsen, Kasper J.
2012-01-01
We discuss the extension of the maximal-unitarity method to two loops, focusing on the example of the planar double box. Maximal cuts are reinterpreted as contour integrals, with the choice of contour fixed by the requirement that integrals of total derivatives vanish on it. The resulting formulae, like their one-loop counterparts, can be applied either analytically or numerically.
Non-planar ABJ theory and parity
International Nuclear Information System (INIS)
Caputa, Pawel; Kristjansen, Charlotte; Zoubos, Konstantinos
2009-01-01
While the ABJ Chern-Simons-matter theory and its string theory dual manifestly lack parity invariance, no sign of parity violation has so far been observed on the weak coupling spin chain side. In particular, the planar two-loop dilatation generator of ABJ theory is parity invariant. In this Letter we derive the non-planar part of the two-loop dilatation generator of ABJ theory in its SU(2)xSU(2) sub-sector. Applying the dilatation generator to short operators, we explicitly demonstrate that, for operators carrying excitations on both spin chains, the non-planar part breaks parity invariance. For operators with only one type of excitation, however, parity remains conserved at the non-planar level. We furthermore observe that, as for ABJM theory, the degeneracy between planar parity pairs is lifted when non-planar corrections are taken into account.
Non-planar ABJ Theory and Parity
DEFF Research Database (Denmark)
Caputa, Pawel; Kristjansen, Charlotte; Zoubos, Konstantinos
2009-01-01
While the ABJ Chern-Simons-matter theory and its string theory dual manifestly lack parity invariance, no sign of parity violation has so far been observed on the weak coupling spin chain side. In particular, the planar two-loop dilatation generator of ABJ theory is parity invariant. In this letter...... we derive the non-planar part of the two-loop dilatation generator of ABJ theory in its SU(2)xSU(2) sub-sector. Applying the dilatation generator to short operators, we explicitly demonstrate that, for operators carrying excitations on both spin chains, the non-planar part breaks parity invariance....... For operators with only one type of excitation, however, parity remains conserved at the non-planar level. We furthermore observe that, as for ABJM theory, the degeneracy between planar parity pairs is lifted when non-planar corrections are taken into account....
Energy Technology Data Exchange (ETDEWEB)
Di Vita, Stefano [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Mastrolia, Pierpaolo; Primo, Amedeo [Padova Univ. (Italy). Dipt. di Fisica ed Astronomia; INFN, Padova (Italy); Schubert, Ulrich [Argonne National Laboratory, Argonne, IL (United States). High Energy Physics Div.
2017-02-15
We compute the two-loop master integrals required for the leading QCD corrections to the interaction vertex of a massive neutral boson X{sup 0}, e.g. H,Z or γ*, with a pair of W bosons, mediated by a SU(2){sub L} quark doublet composed of one massive and one massless flavor. All the external legs are allowed to have arbitrary invariant masses. The Magnus exponential is employed to identify a set of master integrals that, around d=4 space-time dimensions, obey a canonical system of differential equations. The canonical master integrals are given as a Taylor series in ε=(4-d)/2, up to order four, with coeffcients written as combination of Goncharov polylogarithms, respectively up to weight four. In the context of the Standard Model, our results are relevant for the mixed EW-QCD corrections to the Higgs decay to a W pair, as well as to the production channels obtained by crossing, and to the triple gauge boson vertices ZWW and γ{sup *}WW.
Energy Technology Data Exchange (ETDEWEB)
Vita, Stefano Di [DESY,Notkestraße 85, D-22607 Hamburg (Germany); Mastrolia, Pierpaolo; Primo, Amedeo [Dipartimento di Fisica ed Astronomia, Università di Padova,Via Marzolo 8, 35131 Padova (Italy); INFN - Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy); Schubert, Ulrich [High Energy Physics Division, Argonne National Laboratory,Argonne, IL 60439 (United States)
2017-04-03
We compute the two-loop master integrals required for the leading QCD corrections to the interaction vertex of a massive neutral boson X{sup 0}, e.g. H,Z or γ{sup ∗}, with a pair of W bosons, mediated by a SU(2){sub L} quark doublet composed of one massive and one massless flavor. All the external legs are allowed to have arbitrary invariant masses. The Magnus exponential is employed to identify a set of master integrals that, around d=4 space-time dimensions, obey a canonical system of differential equations. The canonical master integrals are given as a Taylor series in ϵ=(4−d)/2, up to order four, with coefficients written as combination of Goncharov polylogarithms, respectively up to weight four. In the context of the Standard Model, our results are relevant for the mixed EW-QCD corrections to the Higgs decay to a W pair, as well as to the production channels obtained by crossing, and to the triple gauge boson vertices ZWW and γ{sup ∗}WW.
Two loops in eleven dimensions
Green, Michael B.; Vanhove, Pierre; Green, Michael B.; Kwon, Hwang-h.; Vanhove, Pierre
2000-01-01
The two-loop Feynman diagram contribution to the four-graviton amplitude of eleven-dimensional supergravity compactified on a two-torus, T^2, is analyzed in detail. The Schwinger parameter integrations are re-expressed as integration over the moduli space of a second torus, \\hat T^2, which enables the leading low-momentum contribution to be evaluated in terms of maps of \\hat T^2 into T^2. The ultraviolet divergences associated with boundaries of moduli space are regularized in a manner that is consistent with the expected duality symmetries of string theory. This leads to an exact expression for terms of order contraction of four Weyl tensors), thereby extending earlier results for the R^4 term that were based on the one-loop eleven-dimensional amplitude. Precise agreement is found with terms in type IIA and IIB superstring theory that arise from the low energy expansion of the tree-level and one-loop string amplitudes and predictions are made for the coefficients of certain two-loop string theory terms as we...
Improved scatter correction with factor analysis for planar and SPECT imaging
Knoll, Peter; Rahmim, Arman; Gültekin, Selma; Šámal, Martin; Ljungberg, Michael; Mirzaei, Siroos; Segars, Paul; Szczupak, Boguslaw
2017-09-01
Quantitative nuclear medicine imaging is an increasingly important frontier. In order to achieve quantitative imaging, various interactions of photons with matter have to be modeled and compensated. Although correction for photon attenuation has been addressed by including x-ray CT scans (accurate), correction for Compton scatter remains an open issue. The inclusion of scattered photons within the energy window used for planar or SPECT data acquisition decreases the contrast of the image. While a number of methods for scatter correction have been proposed in the past, in this work, we propose and assess a novel, user-independent framework applying factor analysis (FA). Extensive Monte Carlo simulations for planar and tomographic imaging were performed using the SIMIND software. Furthermore, planar acquisition of two Petri dishes filled with 99mTc solutions and a Jaszczak phantom study (Data Spectrum Corporation, Durham, NC, USA) using a dual head gamma camera were performed. In order to use FA for scatter correction, we subdivided the applied energy window into a number of sub-windows, serving as input data. FA results in two factor images (photo-peak, scatter) and two corresponding factor curves (energy spectra). Planar and tomographic Jaszczak phantom gamma camera measurements were recorded. The tomographic data (simulations and measurements) were processed for each angular position resulting in a photo-peak and a scatter data set. The reconstructed transaxial slices of the Jaszczak phantom were quantified using an ImageJ plugin. The data obtained by FA showed good agreement with the energy spectra, photo-peak, and scatter images obtained in all Monte Carlo simulated data sets. For comparison, the standard dual-energy window (DEW) approach was additionally applied for scatter correction. FA in comparison with the DEW method results in significant improvements in image accuracy for both planar and tomographic data sets. FA can be used as a user
3D scanning based mold correction for planar and cylindrical parts in aluminum die casting
Directory of Open Access Journals (Sweden)
Takashi Seno
2015-04-01
Full Text Available Aluminum die casting is an important manufacturing process for mechanical components. Die casting is known to be more accurate than other types of casting; however, post-machining is usually necessary to achieve the required accuracy. The goal of this investigation is to develop machining- free aluminum die casting. Improvement of the accuracy of planar and cylindrical parts is expected by correcting metal molds. In the proposed method, the shape of cast aluminum made with the initial metal molds is measured by 3D scanning. The 3D scan data includes information about deformations that occur during casting. Therefore, it is possible to estimate the deformation and correction amounts by comparing 3D scan data with product computer-aided design (CAD data. We corrected planar and cylindrical parts of the CAD data for the mold. In addition, we corrected the planar part of the metal mold using the corrected mold data. The effectiveness of the proposed method is demonstrated by evaluating the accuracy improvement of the cast aluminum made with the corrected mold.
Rigid motion correction of dual opposed planar projections in single photon imaging
Angelis, G. I.; Ryder, W. J.; Gillam, J. E.; Boisson, F.; Kyme, A. Z.; Fulton, R. R.; Meikle, S. R.; Kench, P. L.
2017-05-01
Awake and/or freely moving small animal single photon emission imaging allows the continuous study of molecules exhibiting slow kinetics without the need to restrain or anaesthetise the animals. Estimating motion free projections in freely moving small animal planar imaging can be considered as a limited angle tomography problem, except that we wish to estimate the 2D planar projections rather than the 3D volume, where the angular sampling in all three axes depends on the rotational motion of the animal. In this study, we hypothesise that the motion corrected planar projections estimated by reconstructing an estimate of the 3D volume using an iterative motion compensating reconstruction algorithm and integrating it along the projection path, will closely match the true, motion-less, planar distribution regardless of the object motion. We tested this hypothesis for the case of rigid motion using Monte-Carlo simulations and experimental phantom data based on a dual opposed detector system, where object motion was modelled with 6 degrees of freedom. In addition, we investigated the quantitative accuracy of the regional activity extracted from the geometric mean of opposing motion corrected planar projections. Results showed that it is feasible to estimate qualitatively accurate motion-corrected projections for a wide range of motions around all 3 axes. Errors in the geometric mean estimates of regional activity were relatively small and within 10% of expected true values. In addition, quantitative regional errors were dependent on the observed motion, as well as on the surrounding activity of overlapping organs. We conclude that both qualitatively and quantitatively accurate motion-free projections of the tracer distribution in a rigidly moving object can be estimated from dual opposed detectors using a correction approach within an iterative reconstruction framework and we expect this approach can be extended to the case of non-rigid motion.
A planar-dimensions machine vision measurement method based on lens distortion correction.
Sun, Qiucheng; Hou, Yueqian; Tan, Qingchang; Li, Guannan
2013-01-01
Lens distortion practically presents in a real optical imaging system causing nonuniform geometric distortion in the images and gives rise to additional errors in the vision measurement. In this paper, a planar-dimensions vision measurement method is proposed by improving camera calibration, in which the lens distortion is corrected on the pixel plane of image. The method can be divided into three steps: firstly, the feature points, only in the small central region of the image, are used to get a more accurate perspective projection model; secondly, rather than defining a uniform model, the smoothing spline function is used to describe the lens distortion in the measurement region of image, and two correction functions can be obtained by fitting two deviation surfaces; finally, a measurement method for planar dimensions is proposed, in which accurate magnification factor of imaging system can be obtained by using the correction functions. The effectiveness of the method is demonstrated by applying the proposed method to the test of measuring shaft diameter. Experimental data prove that the accurate planar-dimensions measurements can be performed using the proposed method even if images are deformed by lens distortion.
Block-Matching Distortion Correction of Echo-Planar Images With Opposite Phase Encoding Directions.
Hedouin, Renaud; Commowick, Olivier; Bannier, Elise; Scherrer, Benoit; Taquet, Maxime; Warfield, Simon K; Barillot, Christian
2017-05-01
By shortening the acquisition time of MRI, Echo Planar Imaging (EPI) enables the acquisition of a large number of images in a short time, compatible with clinical constraints as required for diffusion or functional MRI. However such images are subject to large, local distortions disrupting their correspondence with the underlying anatomy. The correction of those distortions is an open problem, especially in regions where large deformations occur. We propose a new block-matching registration method to perform EPI distortion correction based on the acquisition of two EPI with opposite phase encoding directions (PED). It relies on new transformations between blocks adapted to the EPI distortion model, and on an adapted optimization scheme to ensure an opposite symmetric transformation. We present qualitative and quantitative results of the block-matching correction using different metrics on a phantom dataset and on in-vivo data. We show the ability of the block-matching to robustly correct EPI distortion even in strongly affected areas.
A gamma camera count rate saturation correction method for whole-body planar imaging
Hobbs, Robert F.; Baechler, Sébastien; Senthamizhchelvan, Srinivasan; Prideaux, Andrew R.; Esaias, Caroline E.; Reinhardt, Melvin; Frey, Eric C.; Loeb, David M.; Sgouros, George
2010-02-01
Whole-body (WB) planar imaging has long been one of the staple methods of dosimetry, and its quantification has been formalized by the MIRD Committee in pamphlet no 16. One of the issues not specifically addressed in the formalism occurs when the count rates reaching the detector are sufficiently high to result in camera count saturation. Camera dead-time effects have been extensively studied, but all of the developed correction methods assume static acquisitions. However, during WB planar (sweep) imaging, a variable amount of imaged activity exists in the detector's field of view as a function of time and therefore the camera saturation is time dependent. A new time-dependent algorithm was developed to correct for dead-time effects during WB planar acquisitions that accounts for relative motion between detector heads and imaged object. Static camera dead-time parameters were acquired by imaging decaying activity in a phantom and obtaining a saturation curve. Using these parameters, an iterative algorithm akin to Newton's method was developed, which takes into account the variable count rate seen by the detector as a function of time. The algorithm was tested on simulated data as well as on a whole-body scan of high activity Samarium-153 in an ellipsoid phantom. A complete set of parameters from unsaturated phantom data necessary for count rate to activity conversion was also obtained, including build-up and attenuation coefficients, in order to convert corrected count rate values to activity. The algorithm proved successful in accounting for motion- and time-dependent saturation effects in both the simulated and measured data and converged to any desired degree of precision. The clearance half-life calculated from the ellipsoid phantom data was calculated to be 45.1 h after dead-time correction and 51.4 h with no correction; the physical decay half-life of Samarium-153 is 46.3 h. Accurate WB planar dosimetry of high activities relies on successfully compensating
Wit, B. de; Grisaru, M. T.; Nieuwenhuizen, P. van
1993-01-01
We study perturbatively the (conformal) WZNW model. At one loop we compute one-particle irreducible two- and three-point current correlation functions, both in the conventional version and in the classically equivalent, chiral, nonlocal, induced version of the model. At two loops we compute the
The quark beam function at two loops
International Nuclear Information System (INIS)
Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.
2014-01-01
In differential measurements at a hadron collider, collinear initial-state radiation is described by process-independent beam functions. They are the field-theoretic analog of initial-state parton showers. Depending on the measured observable they are differential in the virtuality and/or transverse momentum of the colliding partons in addition to their usual longitudinal momentum fractions. Perturbatively, the beam functions can be calculated by matching them onto standard quark and gluon parton distribution functions. We calculate the inclusive virtuality-dependent quark beam function at NNLO, which is relevant for any observables probing the virtuality of the incoming partons, including N-jettiness and beam thrust. For such observables, our results are an important ingredient in the resummation of large logarithms at N 3 LL order, and provide all contributions enhanced by collinear t-channel singularities at NNLO for quark-initiated processes in analytic form. We perform the calculation in both Feynman and axial gauge and use two different methods to evaluate the discontinuity in the two-loop Feynman diagrams, providing nontrivial checks of the calculation. As part of our results we reproduce the known two-loop QCD splitting functions and confirm at two loops that the virtuality-dependent beam and final-state jet functions have the same anomalous dimension.
The quark beam function at two loops
Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.
2014-04-01
In differential measurements at a hadron collider, collinear initial-state radiation is described by process-independent beam functions. They are the field-theoretic analog of initial-state parton showers. Depending on the measured observable they are differential in the virtuality and/or transverse momentum of the colliding partons in addition to the usual longitudinal momentum fraction. Perturbatively, the beam functions can be calculated by matching them onto standard quark and gluon parton distribution functions. We calculate the inclusive virtuality-dependent quark beam function at NNLO, which is relevant for any observables probing the virtuality of the incoming partons, including N -jettiness and beam thrust. For such observables, our results are an important ingredient in the resummation of large logarithms at N3LL order, and provide all contributions enhanced by collinear t-channel singularities at NNLO for quark-initiated processes in analytic form. We perform the calculation in both Feynman and axial gauge and use two different methods to evaluate the discontinuity of the two-loop Feynman diagrams, providing nontrivial checks of the calculation. As part of our results we reproduce the known two-loop QCD splitting functions and confirm at two loops that the virtuality-dependent beam and final-state jet functions have the same anomalous dimension.
The quark beam function at two loops
Energy Technology Data Exchange (ETDEWEB)
Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.
2014-01-15
In differential measurements at a hadron collider, collinear initial-state radiation is described by process-independent beam functions. They are the field-theoretic analog of initial-state parton showers. Depending on the measured observable they are differential in the virtuality and/or transverse momentum of the colliding partons in addition to their usual longitudinal momentum fractions. Perturbatively, the beam functions can be calculated by matching them onto standard quark and gluon parton distribution functions. We calculate the inclusive virtuality-dependent quark beam function at NNLO, which is relevant for any observables probing the virtuality of the incoming partons, including N-jettiness and beam thrust. For such observables, our results are an important ingredient in the resummation of large logarithms at N{sup 3}LL order, and provide all contributions enhanced by collinear t-channel singularities at NNLO for quark-initiated processes in analytic form. We perform the calculation in both Feynman and axial gauge and use two different methods to evaluate the discontinuity in the two-loop Feynman diagrams, providing nontrivial checks of the calculation. As part of our results we reproduce the known two-loop QCD splitting functions and confirm at two loops that the virtuality-dependent beam and final-state jet functions have the same anomalous dimension.
The quark beam function at two loops
Energy Technology Data Exchange (ETDEWEB)
Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J. [Theory Group, Deutsches Elektronen-Synchrotron (DESY),D-22607 Hamburg (Germany)
2014-04-16
In differential measurements at a hadron collider, collinear initial-state radiation is described by process-independent beam functions. They are the field-theoretic analog of initial-state parton showers. Depending on the measured observable they are differential in the virtuality and/or transverse momentum of the colliding partons in addition to the usual longitudinal momentum fraction. Perturbatively, the beam functions can be calculated by matching them onto standard quark and gluon parton distribution functions. We calculate the inclusive virtuality-dependent quark beam function at NNLO, which is relevant for any observables probing the virtuality of the incoming partons, including N-jettiness and beam thrust. For such observables, our results are an important ingredient in the resummation of large logarithms at N{sup 3}LL order, and provide all contributions enhanced by collinear t-channel singularities at NNLO for quark-initiated processes in analytic form. We perform the calculation in both Feynman and axial gauge and use two different methods to evaluate the discontinuity of the two-loop Feynman diagrams, providing nontrivial checks of the calculation. As part of our results we reproduce the known two-loop QCD splitting functions and confirm at two loops that the virtuality-dependent beam and final-state jet functions have the same anomalous dimension.
Two loop scalar bilinears for inflationary SQED
Energy Technology Data Exchange (ETDEWEB)
Prokopec, T [Institute for Theoretical Physics and Spinoza Institute, Utrecht University Leuvenlaan 4, Postbus 80.195, 3508 TD Utrecht (Netherlands); Tsamis, N C [Department of Physics, University of Crete GR-710 03 Heraklion, Hellas (Greece); Woodard, R P [Department of Physics, University of Florida Gainesville, FL 32611 (United States)
2007-01-07
We evaluate the one- and two-loop contributions to the expectation values of two coincident and gauge invariant scalar bilinears in the theory of massless, minimally coupled scalar quantum electrodynamics on a locally de Sitter background. One of these bilinears is the product of two covariantly differentiated scalars, the other is the product of two undifferentiated scalars. The computations are done using dimensional regularization and the Schwinger-Keldysh formalism. Our results are in perfect agreement with the stochastic predictions at this order.
Anatomy of Two-Loop Effective Action in Noncommutative Field Theories
Kiem, Young-jai; Rey, Soo-Jong; Sato, Haru-Tada
2002-01-01
We compute, at two-loop order, one-particle-irreducible Green functions and effective action in noncommutative $\\lambda[\\Phi^3]_\\star$-theory for both planar (g=0, h=3) and nonplanar (g=1, h=1) contributions. We adopt worldline formulation of the Feynman diagrammatics so that relation to string theory diagrammatics is made transparent in the Seiberg-Witten limit. We argue that the resulting two-loop effective action is expressible via open Wilson lines: one-particle-irreducible effective action is generating functional of connected diagrams for interacting open Wilson lines.
3D Aware Correction and Completion of Depth Maps in Piecewise Planar Scenes
Thabet, Ali Kassem
2015-04-16
RGB-D sensors are popular in the computer vision community, especially for problems of scene understanding, semantic scene labeling, and segmentation. However, most of these methods depend on reliable input depth measurements, while discarding unreliable ones. This paper studies how reliable depth values can be used to correct the unreliable ones, and how to complete (or extend) the available depth data beyond the raw measurements of the sensor (i.e. infer depth at pixels with unknown depth values), given a prior model on the 3D scene. We consider piecewise planar environments in this paper, since many indoor scenes with man-made objects can be modeled as such. We propose a framework that uses the RGB-D sensor’s noise profile to adaptively and robustly fit plane segments (e.g. floor and ceiling) and iteratively complete the depth map, when possible. Depth completion is formulated as a discrete labeling problem (MRF) with hard constraints and solved efficiently using graph cuts. To regularize this problem, we exploit 3D and appearance cues that encourage pixels to take on depth values that will be compatible in 3D to the piecewise planar assumption. Extensive experiments, on a new large-scale and challenging dataset, show that our approach results in more accurate depth maps (with 20 % more depth values) than those recorded by the RGB-D sensor. Additional experiments on the NYUv2 dataset show that our method generates more 3D aware depth. These generated depth maps can also be used to improve the performance of a state-of-the-art RGB-D SLAM method.
Analytic result for the two-loop six-point NMHV amplitude in N=4 super Yang-Mills theory
Dixon, Lance J.; Henn, Johannes M.
2012-01-01
We provide a simple analytic formula for the two-loop six-point ratio function of planar N = 4 super Yang-Mills theory. This result extends the analytic knowledge of multi-loop six-point amplitudes beyond those with maximal helicity violation. We make a natural ansatz for the symbols of the relevant functions appearing in the two-loop amplitude, and impose various consistency conditions, including symmetry, the absence of spurious poles, the correct collinear behaviour, and agreement with the operator product expansion for light-like (super) Wilson loops. This information reduces the ansatz to a small number of relatively simple functions. In order to fix these parameters uniquely, we utilize an explicit representation of the amplitude in terms of loop integrals that can be evaluated analytically in various kinematic limits. The final compact analytic result is expressed in terms of classical polylogarithms, whose arguments are rational functions of the dual conformal cross-ratios, plus precisely two function...
Analytic Result for the Two-loop Six-point NMHV Amplitude in N = 4 Super Yang-Mills Theory
Energy Technology Data Exchange (ETDEWEB)
Dixon, Lance J.; /SLAC; Drummond, James M.; /CERN /Annecy, LAPTH; Henn, Johannes M.; /Humboldt U., Berlin /Princeton, Inst. Advanced Study
2012-02-15
We provide a simple analytic formula for the two-loop six-point ratio function of planar N = 4 super Yang-Mills theory. This result extends the analytic knowledge of multi-loop six-point amplitudes beyond those with maximal helicity violation. We make a natural ansatz for the symbols of the relevant functions appearing in the two-loop amplitude, and impose various consistency conditions, including symmetry, the absence of spurious poles, the correct collinear behavior, and agreement with the operator product expansion for light-like (super) Wilson loops. This information reduces the ansatz to a small number of relatively simple functions. In order to fix these parameters uniquely, we utilize an explicit representation of the amplitude in terms of loop integrals that can be evaluated analytically in various kinematic limits. The final compact analytic result is expressed in terms of classical polylogarithms, whose arguments are rational functions of the dual conformal cross-ratios, plus precisely two functions that are not of this type. One of the functions, the loop integral {Omega}{sup (2)}, also plays a key role in a new representation of the remainder function R{sub 6}{sup (2)} in the maximally helicity violating sector. Another interesting feature at two loops is the appearance of a new (parity odd) x (parity odd) sector of the amplitude, which is absent at one loop, and which is uniquely determined in a natural way in terms of the more familiar (parity even) x (parity even) part. The second non-polylogarithmic function, the loop integral {tilde {Omega}}{sup (2)}, characterizes this sector. Both {Omega}{sup (2)} and {tilde {Omega}}{sup (2)} can be expressed as one-dimensional integrals over classical polylogarithms with rational arguments.
Colour-dressed hexagon tessellations for correlation functions and non-planar corrections
Eden, Burkhard; Jiang, Yunfeng; le Plat, Dennis; Sfondrini, Alessandro
2018-02-01
We continue the study of four-point correlation functions by the hexagon tessellation approach initiated in [38] and [39]. We consider planar tree-level correlation functions in N=4 supersymmetric Yang-Mills theory involving two non-protected operators. We find that, in order to reproduce the field theory result, it is necessary to include SU( N) colour factors in the hexagon formalism; moreover, we find that the hexagon approach as it stands is naturally tailored to the single-trace part of correlation functions, and does not account for multi-trace admixtures. We discuss how to compute correlators involving double-trace operators, as well as more general 1 /N effects; in particular we compute the whole next-to-leading order in the large- N expansion of tree-level BMN two-point functions by tessellating a torus with punctures. Finally, we turn to the issue of "wrapping", Lüscher-like corrections. We show that SU( N) colour-dressing reproduces an earlier empirical rule for incorporating single-magnon wrapping, and we provide a direct interpretation of such wrapping processes in terms of N=2 supersymmetric Feynman diagrams.
Color ferromagnetic vacuum states in QCD and two-loop energy densities
International Nuclear Information System (INIS)
Nielsen, H.B.; Ninomiya, M.
1979-12-01
Two-loop energy densities of color ferromagnetic states are obtained using the β-function calculated to two-loop approximation and the exact formula for the energy density of such a state. This is used to derive bounds on the MIT bag constant correcting the previous bound in one-loop approximation. For a constant field color ferromagnetic ansatz state the bound on the QCD scale parameter Λsub(p) 3 -vacuum ansatz with two-loop and instanton correction gives Λsub(p)<= 0.16 GeV. Tt is stressed that the 'perturbative vacuum', which is identified with the inside bag state is a somewhat ill defined concept due to a path-dependence in the integral giving the energy density. (Auth.)
Papanastasiou, Emmanouil; Moralidis, Efstratios; Siountas, Anastasios
2017-01-01
In cardiac I-123 ( 123 I) imaging downscatter from high energy emissions degrades the image and introduces distortion of semi-quantitative analysis when using a low energy collimator. The effect of a triple energy window (TEW) scatter correction technique, using windows immediately above and below the principal window centered on 159keV, was examined. A hemispherical cardiac phantom was inserted into a cylindrical phantom and both were filled with radioactive 123 I water solutions. Phantoms were submitted to planar and tomographic scintigraphy under various acquisition and processing conditions, including the use of medium energy (ME) and low energy (LE) collimation. In planar imaging, there was a distance dependent count loss with the LEHR collimator which was partly restored with TEW correction. There was minimal dependence of count rate with distance in using ME collimation. Conversely, the heart to background (H/B) ratio increased with increasing distance with the LEHR collimator, but in applying the TEW correction that ratio paralleled the minimally affected values obtained with the ME collimation. In tomographic imaging the acquired H/B ratio was lower with LE collimation alone, in comparison to the ME collimator, but it was raised significantly when applying the TEW scatter correction. Quantitative measurements also depended on the background method and the reconstruction algorithm applied. In cardiac 123 I imaging with a LE collimator the use of TEW scatter correction provides a semi-quantitative assessment comparable to that attained with ME collimation and may moderate inter-institutional inconsistencies.
Two-loop mass splittings in electroweak multiplets: Winos and minimal dark matter
McKay, James; Scott, Pat
2018-03-01
The radiatively-induced splitting of masses in electroweak multiplets is relevant for both collider phenomenology and dark matter. Precision two-loop corrections of O (MeV ) to the triplet mass splitting in the wino limit of the minimal supersymmetric standard model can affect particle lifetimes by up to 40%. We improve on previous two-loop self-energy calculations for the wino model by obtaining consistent input parameters to the calculation via two-loop renormalization-group running, and including the effect of finite light quark masses. We also present the first two-loop calculation of the mass splitting in an electroweak fermionic quintuplet, corresponding to the viable form of minimal dark matter (MDM). We place significant constraints on the lifetimes of the charged and doubly-charged fermions in this model. We find that the two-loop mass splittings in the MDM quintuplet are not constant in the large-mass limit, as might naively be expected from the triplet calculation. This is due to the influence of the additional heavy fermions in loop corrections to the gauge boson propagators.
International Nuclear Information System (INIS)
Borges, J. Sa; Barbosa, J. Soares; Tonasse, M.D.
1998-01-01
In this work we compare two loop Chiral Perturbation Theory calculation of pion-pion scattering with the unitary second order correction to the current algebra soft-pion theorem. It is shown that both methods lead to the same analytic structure for the scattering amplitude. (author)
Two-loop operator matrix elements for massive fermionic local twist-2 operators in QED
International Nuclear Information System (INIS)
Bluemlein, J.; Freitas, A. de; Universidad Simon Bolivar, Caracas; Neerven, W.L. van
2011-11-01
We describe the calculation of the two--loop massive operator matrix elements with massive external fermions in QED. We investigate the factorization of the O(α 2 ) initial state corrections to e + e - annihilation into a virtual boson for large cms energies s >>m 2 e into massive operator matrix elements and the massless Wilson coefficients of the Drell-Yan process adapting the color coefficients to the case of QED, as proposed by F. A. Berends et. al. (Nucl. Phys. B 297 (1988)429). Our calculations show explicitly that the representation proposed there works at one-loop order and up to terms linear in ln (s/m 2 e ) at two-loop order. However, the two-loop constant part contains a few structural terms, which have not been obtained in previous direct calculations. (orig.)
The two-loop master integrals for qq-bar→VV
International Nuclear Information System (INIS)
Gehrmann, Thomas; Manteuffel, Andreas von; Tancredi, Lorenzo; Weihs, Erich
2014-01-01
We compute the full set of two-loop Feynman integrals appearing in massless two-loop four-point functions with two off-shell legs with the same invariant mass. These integrals allow to determine the two-loop corrections to the amplitudes for vector boson pair production at hadron colliders, qq-bar→VV, and thus to compute this process to next-to-next-to-leading order accuracy in QCD. The master integrals are derived using the method of differential equations, employing a canonical basis for the integrals. We obtain analytical results for all integrals, expressed in terms of multiple polylogarithms. We optimize our results for numerical evaluation by employing functions which are real valued for physical scattering kinematics and allow for an immediate power series expansion
Massive planar and non-planar double box integrals for light N f contributions to
von Manteuffel, Andreas; Studerus, Cedric
2013-10-01
We present the master integrals needed for the light fermionic two-loop corrections to top quark pair production in the gluon fusion channel. Via the method of differential equations we compute the results in terms of multiple polylogarithms in a Laurent series about d = 4, where d is the space-time dimension. The most involved topology is a non-planar double box with one internal mass. We employ the coproduct-augmented symbol calculus and show that significant simplifications are possible for selected results using an optimised set of multiple polylogarithms.
The massless two-loop two-point function
International Nuclear Information System (INIS)
Bierenbaum, I.; Weinzierl, S.
2003-01-01
We consider the massless two-loop two-point function with arbitrary powers of the propagators and derive a representation from which we can obtain the Laurent expansion to any desired order in the dimensional regularization parameter ε. As a side product, we show that in the Laurent expansion of the two-loop integral only rational numbers and multiple zeta values occur. Our method of calculation obtains the two-loop integral as a convolution product of two primitive one-loop integrals. We comment on the generalization of this product structure to higher loop integrals. (orig.)
Low-energy effective action in two-dimensional SQED: a two-loop analysis
Samsonov, I. B.
2017-07-01
We study two-loop quantum corrections to the low-energy effective actions in N=(2,2) and N=(4,4) SQED on the Coulomb branch. In the latter model, the low-energy effective action is described by a generalized Kähler potential which depends on both chiral and twisted chiral superfields. We demonstrate that this generalized Kähler potential is one-loop exact and corresponds to the N=(4,4) sigma-model with torsion presented by Roček, Schoutens and Sevrin [1]. In the N=(2,2) SQED, the effective Kähler potential is not protected against higher-loop quantum corrections. The two-loop quantum corrections to this potential and the corresponding sigma-model metric are explicitly found.
Two-loop renormalization of Feynman gauge QED
International Nuclear Information System (INIS)
Adkins, Gregory S.; Fell, Richard N.; Sapirstein, J.
2001-01-01
We calculate the two-loop renormalization constants deltam, Z 1 , and Z 2 in Feynman gauge QED using dimensional regularization to control ultraviolet divergences and a non-zero photon mass to regulate infrared divergences
Bytev, V V; Shaikhatdenov, B G
2002-01-01
We consider a process of quasielastic e\\mu large-angle scattering at high energies with radiative corrections up to a two-loop level. The lowest order radiative correction arising both from one-loop virtual photon emission and a real soft emission are presented to a power accuracy. Two-loop level corrections are supposed to be of three gauge-invariant classes. One of them, so-called vertex contribution, is given in logarithmic approximation. Relation with the renormalization group approach is discussed.
(Quasi)Elastic Electron-Muon Large-Angle Scattering to a Two-Loop Approximation Vertex Contributions
Bytev, V V; Shaikhatdenov, B G
2002-01-01
We consider a process of quasielastic e\\mu large-angle scattering at high energies with radiative corrections up to a two-loop level. The lowest order radiative correction arising both from one-loop virtual photon emission and a real soft emission are presented to a power accuracy. Two-loop level corrections are supposed to be of three gauge-invariant classes. One of them, so-called vertex contribution, is given in logarithmic approximation. Relation with the renormalization group approach is discussed.
Heavy-quark production in gluon fusion at two loops in QCD
International Nuclear Information System (INIS)
Czakon, M.
2007-07-01
We present the two-loop virtual QCD corrections to the production of heavy quarks in gluon fusion. The results are exact in the limit when all kinematical invariants are large compared to the mass of the heavy quark up to terms suppressed by powers of the heavy-quark mass. Our derivation uses a simple relation between massless and massive QCD scattering amplitudes as well as a direct calculation of the massive amplitude at two loops. The results presented here together with those obtained previously for quark-quark scattering form important parts of the next-to-next-to-leading order QCD corrections to heavy-quark production in hadron-hadron collisions. (orig.)
New perturbative upper bound on MH from fermionic Higgs decays at two loops
International Nuclear Information System (INIS)
Durand, L.; Kniehl, B.A.; Riesselmann, K.
1993-09-01
We present the dominant two-loop O (G F 2 M H 4 ) electroweak corrections to the fermionic decay widths of a high-mass Higgs boson in the Standard Model. The corrections are negative and quite significant, and are larger in magnitude than the one-loop electroweak corrections for M H > or ∼400 GeV. This indicates the onset of a breakdown of perturbation theory in the Higgs sector of the Standard Model at this surprisingly low value of the Higgs boson mass. (orig.)
Comments on two-loop Kac-Moody algebras
International Nuclear Information System (INIS)
Ferreira, L.A.; Gomes, J.F.; Zimerman, A.H.; Schwimmer, A.
1991-10-01
It is shown that the two-loop Kac-Moody algebra is equivalent to a two variable loop algebra and a decouple β-γ system. Similarly WZNW and CSW models having as algebraic structure the Kac-Moody algebra are equivalent to an infinity to versions of the corresponding ordinary models and decoupled Abelian fields. (author). 15 refs
Heavy quark form factors at two loops in perturbative QCD
Energy Technology Data Exchange (ETDEWEB)
Ablinger, J.; Schneider, C. [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation (RISC); Behring, A. [RWTH Aachen Univ. (Germany). Inst. fuer Theoretische Teilchenphysik und Kosmologie; Bluemlein, J.; Freitas, A. de; Marquard, P.; Rana, N. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Falcioni, G. [Nikhef, Amsterdam (Netherlands). Theory Group
2017-11-15
We present the results for heavy quark form factors at two-loop order in perturbative QCD for different currents, namely vector, axial-vector, scalar and pseudo-scalar currents, up to second order in the dimensional regularization parameter. We outline the necessary computational details, ultraviolet renormalization and corresponding universal infrared structure.
Two-loop QED operator matrix elements with massive external fermion lines
Energy Technology Data Exchange (ETDEWEB)
Bluemlein, Johannes [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Freitas, Abilio de [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Universidad Simon Bolivar, Caracas (Venezuela). Dept. de Fisica; Neerven, Wilhelmus van [Leiden Univ. (Netherlands). Institut-Lorentz
2011-07-15
The two-loop massive operator matrix elements for the fermionic local twist-2 operators with external massive fermion lines in Quantum Electrodynamics (QED) are calculated up to the constant terms in the dimensional parameter {epsilon}=D-4. We investigate the hypothesis of F. A. Berends et al. (1988) that the 2-loop QED initial state corrections to e{sup +}e{sup -} annihilation into a virtual neutral gauge boson, except power corrections of O((m{sup 2}{sub f}/s){sup k}), k {>=} 1, can be represented in terms of these matrix elements and the massless 2-loop Wilson coefficients of the Drell-Yan process. (orig.)
Nunes, Rita G; Hajnal, Joseph V
2018-01-03
Point spread function (PSF) mapping enables estimating the displacement fields required for distortion correction of echo planar images. Recently, a highly accelerated approach was introduced for estimating displacements from the phase slope of under-sampled PSF mapping data. Sampling schemes with varying spacing were proposed requiring stepwise phase unwrapping. To avoid unwrapping errors, an alternative approach applying the concept of finite rate of innovation to PSF mapping (FRIP) is introduced, using a pattern search strategy to locate the PSF peak, and the two methods are compared. Fully sampled PSF data was acquired in six subjects at 3.0 T, and distortion maps were estimated after retrospective under-sampling. The two methods were compared for both previously published and newly optimized sampling patterns. Prospectively under-sampled data were also acquired. Shift maps were estimated and deviations relative to the fully sampled reference map were calculated. The best performance was achieved when using FRIP with a previously proposed sampling scheme. The two methods were comparable for the remaining schemes. The displacement field errors tended to be lower as the number of samples or their spacing increased. A robust method for estimating the position of the PSF peak has been introduced.
International Nuclear Information System (INIS)
Kuttig, Jan; Steiding, Christian; Hupfer, Martin; Karolczak, Marek; Kolditz, Daniel
2015-01-01
In this study we compared various defect pixel correction methods for reducing artifact appearance within projection images used for computed tomography (CT) reconstructions.Defect pixel correction algorithms were examined with respect to their artifact behaviour within planar projection images as well as in volumetric CT reconstructions. We investigated four algorithms: nearest neighbour, linear and adaptive linear interpolation, and a frequency-selective spectral-domain approach.To characterise the quality of each algorithm in planar image data, we inserted line defects of varying widths and orientations into images. The structure preservation of each algorithm was analysed by corrupting and correcting the image of a slit phantom pattern and by evaluating its line spread function (LSF). The noise preservation was assessed by interpolating corrupted flat images and estimating the noise power spectrum (NPS) of the interpolated region.For the volumetric investigations, we examined the structure and noise preservation within a structured aluminium foam, a mid-contrast cone-beam phantom and a homogeneous Polyurethane (PUR) cylinder.The frequency-selective algorithm showed the best structure and noise preservation for planar data of the correction methods tested. For volumetric data it still showed the best noise preservation, whereas the structure preservation was outperformed by the linear interpolation.The frequency-selective spectral-domain approach in the correction of line defects is recommended for planar image data, but its abilities within high-contrast volumes are restricted. In that case, the application of a simple linear interpolation might be the better choice to correct line defects within projection images used for CT. (paper)
The two-loop symbol of all multi-Regge regions
International Nuclear Information System (INIS)
Bargheer, Till; Papathanasiou, Georgios; Schomerus, Volker
2016-01-01
We study the symbol of the two-loop n-gluon MHV amplitude for all Mandelstam regions in multi-Regge kinematics in N=4 super Yang-Mills theory. While the number of distinct Mandelstam regions grows exponentially with n, the increase of independent symbols turns out to be merely quadratic. We uncover how to construct the symbols for any number of external gluons from just two building blocks which are naturally associated with the six- and seven-gluon amplitude, respectively. The second building block is entirely new, and in addition to its symbol, we also construct a prototype function that correctly reproduces all terms of maximal functional transcendentality.
The two-loop symbol of all multi-Regge regions
International Nuclear Information System (INIS)
Bargheer, Till; Schomerus, Volker; Papathanasiou, Georgios
2015-12-01
We study the symbol of the two-loop n-gluon MHV amplitude for all Mandelstam regions in multi-Regge kinematics in N= 4 super Yang-Mills theory. While the number of distinct Mandelstam regions grows exponentially with n, the increase of independent symbols turns out to be merely quadratic. We uncover how to construct the symbols for any number of external gluons from just two building blocks which are naturally associated with the six- and seven-gluon amplitude, respectively. The second building block is entirely new, and in addition to its symbol, we also construct a prototype function that correctly reproduces all terms of maximal functional transcendentality.
QCD pressure at two loops in the temporal gauge
Leibbrandt, G; Staley, M F
1996-01-01
We apply the method of \\underline{zeta} functions, together with the $n_\\mu^*$-prescription for the temporal gauge, to evaluate the thermodynamic pressure in QCD at finite temperature $T$. Working in the imaginary-time formalism and employing a special version of the unified-gauge prescription, we show that the pure-gauge contribution to the pressure at two loops is given by $P_2^{\\mbox{{\\scriptsize gauge}}} = -(g^2/144)N_cN_gT^4$, where $N_c$ and $N_g$ denote the number of colours and gluons...
The impact of two-loop effects on the scenario of MSSM Higgs alignment without decoupling
Energy Technology Data Exchange (ETDEWEB)
Haber, Howard E.; Stefaniak, Tim [University of California, Santa Cruz Institute for Particle Physics (SCIPP) and Department of Physics, Santa Cruz, CA (United States); Heinemeyer, Sven [Campus of International Excellence UAM+CSIC, Madrid (Spain); Universidad Autonoma de Madrid, Instituto de Fisica Teorica, (UAM/CSIC), Madrid (Spain); Instituto de Fisica de Cantabria (CSIC-UC), Santander (Spain)
2017-11-15
In multi-Higgs models, the properties of one neutral scalar state approximate those of the Standard Model (SM) Higgs boson in a limit where the corresponding scalar field is roughly aligned in field space with the scalar doublet vacuum expectation value. In a scenario of alignment without decoupling, a SM-like Higgs boson can be accompanied by additional scalar states whose masses are of a similar order of magnitude. In the Minimal Supersymmetric Standard Model (MSSM), alignment without decoupling can be achieved due to an accidental cancellation of tree-level and radiative loop-level effects. In this paper we assess the impact of the leading two-loop O(α{sub s}h{sub t}{sup 2}) corrections on the Higgs alignment condition in the MSSM. These corrections are sizable and important in the relevant regions of parameter space and furthermore give rise to solutions of the alignment condition that are not present in the approximate one-loop description. We provide a comprehensive numerical comparison of the alignment condition obtained in the approximate one-loop and two-loop approximations, and discuss its implications for phenomenologically viable regions of the MSSM parameter space. (orig.)
Two-loop disorder effects on the nematic quantum criticality in d-wave superconductors
International Nuclear Information System (INIS)
Wang, Jing
2015-01-01
The gapless nodal fermions exhibit non-Fermi liquid behaviors at the nematic quantum critical point that is supposed to exist in some d-wave cuprate superconductors. This non-Fermi liquid state may be turned into a disorder-dominated diffusive metal if the fermions also couple to a disordered potential that generates a relevant perturbation in the sense of renormalization group theory. It is therefore necessary to examine whether a specific disorder is relevant or not. We study the interplay between critical nematic fluctuation and random chemical potential by performing renormalization group analysis. The parameter that characterizes the strength of random chemical potential is marginal at the one-loop level, but becomes marginally relevant after including the two-loop corrections. Thus even weak random chemical potential leads to diffusive motion of nodal fermions and the significantly critical behaviors of physical implications, since the strength flows eventually to large values at low energies. - Highlights: • The gapless nodal fermions exhibit non-Fermi liquid behaviors at the nematic QCP. • The strength of random chemical potential is marginal at the one-loop level. • The strength becomes marginally relevant after including the two-loop corrections. • The diffusive metallic state is induced by the marginally relevant disorder. • The behaviors of some physical observables are presented at the nematic QCP
Anastasiou, C; Bucherer, S; Daleo, A; Kunszt, Zoltán; Anastasiou, Charalampos; Beerli, Stefan; Bucherer, Stefan; Daleo, Alejandro; Kunszt, Zoltan
2007-01-01
We compute all two-loop master integrals which are required for the evaluation of next-to-leading order QCD corrections in Higgs boson production via gluon fusion. Many two-loop amplitudes for 2 -> 1 processes in the Standard Model and beyond can be expressed in terms of these integrals using automated reduction techniques. These integrals also form a subset of the master integrals for more complicated 2 -> 2 amplitudes with massive propagators in the loops. As a first application, we evaluate the two-loop amplitude for Higgs boson production in gluon fusion via a massive quark. Our result is the first independent check of the calculation of Spira, Djouadi, Graudenz and Zerwas. We also present for the first time the two-loop amplitude for gg -> h via a massive squark.
Infrared divergences and harmonic anomalies in the two-loop superstring effective action
Pioline, Boris
2015-01-01
We analyze the pertubative contributions to the $D^4 R^4$ and $D^6 R^4$ couplings in the low-energy effective action of type II string theory compactified on a torus $T^d$, with particular emphasis on two-loop corrections. In general, it is necessary to introduce an infrared cut-off $\\Lambda$ to separate local interactions from non-local effects due to the exchange of massless states. We identify the degenerations of the genus-two Riemann surface which are responsible for power-like dependence on $\\Lambda$, and give an explicit prescription for extracting the $\\Lambda$-independent effective couplings. These renormalized couplings are then shown to be eigenmodes of the Laplace operator with respect to the torus moduli, up to computable anomalous source terms arising in the presence of logarithmic divergences, in precise agreement with predictions from U-duality. Our results for the two-loop $D^6 R^4$ contribution also probe essential properties of the Kawazumi-Zhang invariant
Two-loop scale-invariant scalar potential and quantum effective operators
Ghilencea, D.M.
2016-11-29
Spontaneous breaking of quantum scale invariance may provide a solution to the hierarchy and cosmological constant problems. In a scale-invariant regularization, we compute the two-loop potential of a higgs-like scalar $\\phi$ in theories in which scale symmetry is broken only spontaneously by the dilaton ($\\sigma$). Its vev $\\langle\\sigma\\rangle$ generates the DR subtraction scale ($\\mu\\sim\\langle\\sigma\\rangle$), which avoids the explicit scale symmetry breaking by traditional regularizations (where $\\mu$=fixed scale). The two-loop potential contains effective operators of non-polynomial nature as well as new corrections, beyond those obtained with explicit breaking ($\\mu$=fixed scale). These operators have the form: $\\phi^6/\\sigma^2$, $\\phi^8/\\sigma^4$, etc, which generate an infinite series of higher dimensional polynomial operators upon expansion about $\\langle\\sigma\\rangle\\gg \\langle\\phi\\rangle$, where such hierarchy is arranged by {\\it one} initial, classical tuning. These operators emerge at the quantum...
Infrared divergences and harmonic anomalies in the two-loop superstring effective action
Energy Technology Data Exchange (ETDEWEB)
Pioline, Boris [CERN PH-TH,Case C01600, CERN, CH-1211 Geneva 23 (Switzerland); Sorbonne Universités,UPMC Université Paris 6, UMR 7589, F-75005 Paris (France); Laboratoire de Physique Théorique et Hautes Energies, CNRS UMR 7589,Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris cedex 05 (France); Russo, Rodolfo [Centre for Research in String Theory, School of Physics and Astronomy,Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom)
2015-12-16
We analyze the pertubative contributions to the D{sup 4}R{sup 4} and D{sup 6}R{sup 4} couplings in the low-energy effective action of type II string theory compactified on a torus T{sup d}, with particular emphasis on two-loop corrections. In general, it is necessary to introduce an infrared cut-off Λ to separate local interactions from non-local effects due to the exchange of massless states. We identify the degenerations of the genus-two Riemann surface which are responsible for power-like dependence on Λ, and give an explicit prescription for extracting the Λ-independent effective couplings. These renormalized couplings are then shown to be eigenmodes of the Laplace operator with respect to the torus moduli, up to computable anomalous source terms arising in the presence of logarithmic divergences, in precise agreement with predictions from U-duality. Our results for the two-loop D{sup 6}R{sup 4} contribution also probe essential properties of the Kawazumi-Zhang invariant.
The Effective Field Theory of Large Scale Structures at two loops
International Nuclear Information System (INIS)
Carrasco, John Joseph M.; Foreman, Simon; Green, Daniel; Senatore, Leonardo
2014-01-01
Large scale structure surveys promise to be the next leading probe of cosmological information. It is therefore crucial to reliably predict their observables. The Effective Field Theory of Large Scale Structures (EFTofLSS) provides a manifestly convergent perturbation theory for the weakly non-linear regime of dark matter, where correlation functions are computed in an expansion of the wavenumber k of a mode over the wavenumber associated with the non-linear scale k NL . Since most of the information is contained at high wavenumbers, it is necessary to compute higher order corrections to correlation functions. After the one-loop correction to the matter power spectrum, we estimate that the next leading one is the two-loop contribution, which we compute here. At this order in k/k NL , there is only one counterterm in the EFTofLSS that must be included, though this term contributes both at tree-level and in several one-loop diagrams. We also discuss correlation functions involving the velocity and momentum fields. We find that the EFTofLSS prediction at two loops matches to percent accuracy the non-linear matter power spectrum at redshift zero up to k∼ 0.6 h Mpc −1 , requiring just one unknown coefficient that needs to be fit to observations. Given that Standard Perturbation Theory stops converging at redshift zero at k∼ 0.1 h Mpc −1 , our results demonstrate the possibility of accessing a factor of order 200 more dark matter quasi-linear modes than naively expected. If the remaining observational challenges to accessing these modes can be addressed with similar success, our results show that there is tremendous potential for large scale structure surveys to explore the primordial universe
Rück, Marlon; Reuther, Johannes
2018-04-01
We implement an extension of the pseudofermion functional renormalization group method for quantum spin systems that takes into account two-loop diagrammatic contributions. An efficient numerical treatment of the additional terms is achieved within a nested graph construction which recombines different one-loop interaction channels. In order to be fully self-consistent with respect to self-energy corrections, we also include certain three-loop terms of Katanin type. We first apply this formalism to the antiferromagnetic J1-J2 Heisenberg model on the square lattice and benchmark our results against the previous one-loop plus Katanin approach. Even though the renormalization group (RG) equations undergo significant modifications when including the two-loop terms, the magnetic phase diagram, comprising Néel ordered and collinear ordered phases separated by a magnetically disordered regime, remains remarkably unchanged. Only the boundary position between the disordered and the collinear phases is found to be moderately affected by two-loop terms. On the other hand, critical RG scales, which we associate with critical temperatures Tc, are reduced by a factor of ˜2 indicating that the two-loop diagrams play a significant role in enforcing the Mermin-Wagner theorem. Improved estimates for critical temperatures are also obtained for the Heisenberg ferromagnet on the three-dimensional simple cubic lattice where errors in Tc are reduced by ˜34 % . These findings have important implications for the quantum phase diagrams calculated within the previous one-loop plus Katanin approach which turn out to be already well converged.
The Effective Field Theory of Large Scale Structures at Two Loops
Carrasco, John Joseph M.; Green, Daniel; Senatore, Leonardo
2014-01-01
Large scale structure surveys promise to be the next leading probe of cosmological information. It is therefore crucial to reliably predict their observables. The Effective Field Theory of Large Scale Structures (EFTofLSS) provides a manifestly convergent perturbation theory for the weakly non-linear regime of dark matter, where correlation functions are computed in an expansion of the wavenumber k of a mode over the wavenumber associated with the non-linear scale k_nl. Since most of the information is contained at high wavenumbers, it is necessary to compute higher order corrections to correlation functions. After the one-loop correction to the matter power spectrum, we estimate that the next leading one is the two-loop contribution, which we compute here. At this order in k/k_nl, there is only one counterterm in the EFTofLSS that must be included, though this term contributes both at tree-level and in several one-loop diagrams. We also discuss correlation functions involving the velocity and momentum fields...
Two-loop matching of the dipole operators for b→sγ and b→sg
International Nuclear Information System (INIS)
Greub, C.; Hurth, T.
1997-01-01
The order α s corrections to the Wilson coefficients of the dipole operators (O 7 ,O 8 ) at the matching scale μ=m W are a crucial ingredient for a complete next-to-leading logarithmic calculation of the branching ratio for b→sγ. Given the phenomenological relevance and the fact that this two-loop calculation has been done so far only by Adel and Yao, we present a detailed recalculation using a different method. Our results are in complete agreement with those of Adel and Yao. copyright 1997 The American Physical Society
On Vanishing Two Loop Cosmological Constants in Nonsupersymmetric Strings
Energy Technology Data Exchange (ETDEWEB)
Kachru, S
1998-10-22
It has recently been suggested that in certain special nonsupersymmetric type II string compactifications, at least the first two perturbative contributions to the cosmological constant Lambda vanish. Support for perturbative vanishing beyond 1-loop (as well as evidence for the absence of some nonperturbative contributions) has come from duality arguments. There was also a direct 2-loop computation which was incomplete; in this note we explain the deficiency of the previous 2-loop calculation and discuss the complete 2-loop computation in two different models. The corrected analysis yields a vanishing 2-loop contribution to Lambda in these models.
Two-loop beam and soft functions for rapidity-dependent jet vetoes
Energy Technology Data Exchange (ETDEWEB)
Gangal, Shireen [Theory Group, Deutsches Elektronen-Synchrotron (DESY),Notkestraße 85, D-22607 Hamburg (Germany); Gaunt, Jonathan R. [Nikhef Theory Group and VU University Amsterdam,De Boelelaan 1081, NL-1081 HV Amsterdam (Netherlands); Stahlhofen, Maximilian [PRISMA Cluster of Excellence, Institute of Physics, Johannes Gutenberg University,Staudingerweg 7, D-55128 Mainz (Germany); Tackmann, Frank J. [Theory Group, Deutsches Elektronen-Synchrotron (DESY),Notkestraße 85, D-22607 Hamburg (Germany)
2017-02-06
Jet vetoes play an important role in many analyses at the LHC. Traditionally, jet vetoes have been imposed using a restriction on the transverse momentum p{sub Tj} of jets. Alternatively, one can also consider jet observables for which p{sub Tj} is weighted by a smooth function of the jet rapidity y{sub j} that vanishes as |y{sub j}|→∞. Such observables are useful as they provide a natural way to impose a tight veto on central jets but a looser one at forward rapidities. We consider two such rapidity-dependent jet veto observables, T{sub Bj} and T{sub Cj}, and compute the required beam and dijet soft functions for the jet-vetoed color-singlet production cross section at two loops. At this order, clustering effects from the jet algorithm become important. The dominant contributions are computed fully analytically while corrections that are subleading in the limit of small jet radii are expressed in terms of finite numerical integrals. Our results enable the full NNLL{sup ′} resummation and are an important step towards N{sup 3}LL resummation for cross sections with a T{sub Bj} or T{sub Cj} jet veto.
Two-loop beam and soft functions for rapidity-dependent jet vetoes
Energy Technology Data Exchange (ETDEWEB)
Gangal, Shireen; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Gaunt, Jonathan R. [Amsterdam VU Univ. (Netherlands). NIKHEF Theory Group; Stahlhofen, Maximilian [Mainz Univ. (Germany). PRISMA Cluster of Excellence
2016-08-15
Jet vetoes play an important role in many analyses at the LHC. Traditionally, jet vetoes have been imposed using a restriction on the transverse momentum p{sub Tj} of jets. Alternatively, one can also consider jet observables for which p{sub Tj} is weighted by a smooth function of the jet rapidity y{sub j} that vanishes as vertical stroke y{sub j} vertical stroke →∞. Such observables are useful as they provide a natural way to impose a tight veto on central jets but a looser one at forward rapidities. We consider two such rapidity-dependent jet veto observables, Τ{sub Bj} and Τ{sub Cj}, and compute the required beam and dijet soft functions for the jet-vetoed colorsinglet production cross section at two loops. At this order, clustering effects from the jet algorithm become important. The dominant contributions are computed fully analytically while corrections that are subleading in the limit of small jet radii are expressed in terms of finite numerical integrals. Our results enable the full NNLL' resummation and are an important step towards N{sup 3}LL resummation for cross sections with a Τ{sub Bj} or Τ{sub Cj} jet veto.
Two-loop beam and soft functions for rapidity-dependent jet vetoes
Gangal, Shireen; Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.
2017-02-01
Jet vetoes play an important role in many analyses at the LHC. Traditionally, jet vetoes have been imposed using a restriction on the transverse momentum p Tj of jets. Alternatively, one can also consider jet observables for which p Tj is weighted by a smooth function of the jet rapidity y j that vanishes as | y j | → ∞. Such observables are useful as they provide a natural way to impose a tight veto on central jets but a looser one at forward rapidities. We consider two such rapidity-dependent jet veto observables, T_{Bj} and {T_{Cj} , and compute the required beam and dijet soft functions for the jet-vetoed color-singlet production cross section at two loops. At this order, clustering effects from the jet algorithm become important. The dominant contributions are computed fully analytically while corrections that are subleading in the limit of small jet radii are expressed in terms of finite numerical integrals. Our results enable the full NNLL' resummation and are an important step towards N3LL resummation for cross sections with a T_{Bj} or T_{Cj} jet veto.
New class of two-loop neutrino mass models with distinguishable phenomenology
Cao, Qing-Hong; Chen, Shao-Long; Ma, Ernest; Yan, Bin; Zhang, Dong-Ming
2018-04-01
We discuss a new class of neutrino mass models generated in two loops, and explore specifically three new physics scenarios: (A) doubly charged scalar, (B) dark matter, and (C) leptoquark and diquark, which are verifiable at the 14 TeV LHC Run-II. We point out how the different Higgs insertions will distinguish our two-loop topology with others if the new particles in the loop are in the simplest representations of the SM gauge group.
Two loop effective Kahler potential of (non)-renormalizable supersymmetric models
International Nuclear Information System (INIS)
Groot Nibbelink, S.; Nyawelo, T.S.
2005-10-01
We perform a supergraph computation of the effective Kahler potential at one and two loops for general four dimensional N=1 supersymmetric theories described by arbitrary Kahler potential, superpotential and gauge kinetic function. We only insist on gauge invariance of the Kahler potential and the superpotential as we heavily rely on its consequences in the quantum theory. However, we do not require gauge invariance for the gauge kinetic functions, so that our results can also be applied to anomalous theories that involve the Green-Schwarz mechanism. We illustrate our two loop results by considering a few simple models: the (non-)renormalizable Wess-Zumino model and Super Quantum Electrodynamics. (author)
Local momentum space and two-loop renormalizability of λφ 4 field theory in curved space-time
Bunch, T. S.
1981-07-01
A generalization is given of some previous work in which a momentum space representation for the Feynman propagator,G(x, y), of a scalar field in an arbitrary curved space-time was obtained. The pointsx andy are allowed to vary in a normal neighborhood of an arbitrary fixed pointz which is taken as an origin of normal coordinates and the representation is obtained by Fourier transformation in the coordinate differencex α-y α. The generality of this representation enables it to be applied to the evaluation of the divergences in any Feynman graph. As an example, the third-order (two-loop) corrections to the four-point function of λø4 field theory are shown to be renormalizable in curved space-time.
Pion-pion phase shifts from two loop chiral perturbation theory
International Nuclear Information System (INIS)
Borges, J. Sa; Barbosa, J. Soares; Tonasse, M.
1999-01-01
We present a two parameters fit of low energy P-wave shifts, using the recent published results of pion-pion scattering amplitudes from chiral perturbation theory, including two loops contributions. We show that, once given the P-wave, the isospin zero S-waves is in good agreement with experimental data. (author)
Two-loop beta-functions of the sine-Gordon model
Balog, János; Hegedus, Árpád
2000-09-01
We recalculate the two-loop beta-functions in the two-dimensional sine-Gordon model in a two-parameter expansion around the asymptotically free point. Our results agree with those of Amit et al (Amit D J, Goldschmidt Y Y and Grinstein G 1980 J. Phys. A: Math. Gen. 13 585).
The complete two-loop integrated jet thrust distribution in soft-collinear effective theory
Energy Technology Data Exchange (ETDEWEB)
von Manteuffel, Andreas; Schabinger, Robert M.; Zhu, Hua Xing
2014-03-01
In this work, we complete the calculation of the soft part of the two-loop integrated jet thrust distribution in e+e- annihilation. This jet mass observable is based on the thrust cone jet algorithm, which involves a veto scale for out-of-jet radiation. The previously uncomputed part of our result depends in a complicated way on the jet cone size, r, and at intermediate stages of the calculation we actually encounter a new class of multiple polylogarithms. We employ an extension of the coproduct calculus to systematically exploit functional relations and represent our results concisely. In contrast to the individual contributions, the sum of all global terms can be expressed in terms of classical polylogarithms. Our explicit two-loop calculation enables us to clarify the small r picture discussed in earlier work. In particular, we show that the resummation of the logarithms of r that appear in the previously uncomputed part of the two-loop integrated jet thrust distribution is inextricably linked to the resummation of the non-global logarithms. Furthermore, we find that the logarithms of r which cannot be absorbed into the non-global logarithms in the way advocated in earlier work have coefficients fixed by the two-loop cusp anomalous dimension. We also show that in many cases one can straightforwardly predict potentially large logarithmic contributions to the integrated jet thrust distribution at L loops by making use of analogous contributions to the simpler integrated hemisphere soft function.
PyR@TE 2: A Python tool for computing RGEs at two-loop
Lyonnet, F.; Schienbein, I.
2017-04-01
Renormalization group equations are an essential tool for the description of theories across different energy scales. Even though their expressions at two-loop for an arbitrary gauge field theory have been known for more than thirty years, deriving the full set of equations for a given model by hand is very challenging and prone to errors. To tackle this issue, we have introduced in Lyonnet et al. (2014) a Python tool called PyR@TE; Python Renormalization group equations @ Two-loop for Everyone. With PyR@TE, it is easy to implement a given Lagrangian and derive the complete set of two-loop RGEs for all the parameters of the theory. In this paper, we present the new version of this code, PyR@TE 2, which brings many new features and in particular it incorporates kinetic mixing when several U(1) gauge groups are involved. In addition, the group theory part has been greatly improved as we introduced a new Python module dubbed PyLie that deals with all the group theoretical aspects required for the calculation of the RGEs as well as providing very useful model building capabilities. This allows the use of any irreducible representation of the SU(n) , SO(2 n) and SO(2n + 1) groups. Furthermore, it is now possible to implement terms in the Lagrangian involving fields which can be contracted into gauge singlets in more than one way. As a byproduct, results for a popular model (SM + complex triplet) for which, to our knowledge, the complete set of two-loop RGEs has not been calculated before are presented in this paper. Finally, the two-loop RGEs for the anomalous dimension of the scalar and fermion fields have been implemented as well. It is now possible to export the coupled system of beta functions into a numerical C++ function, leading to a consequent speed up in solving them.
Planar and non-planar Wilson loops in QCD
International Nuclear Information System (INIS)
Bagan, E.; Latorre, J.I.; Massachusetts Inst. of Tech., Cambridge
1988-01-01
A general QCD sum rule calculation of vacuum expectation values of Wilson loops is presented and particularized to several specific planar and non-planar contours. The string tension obtained is √σ = 0.50(5) GeV. Within the errors of the approach, this result is shape-independent. We comment on the possibility that corrections to the area and perimeter laws could be parametrized by a geodesic curvature term. (orig.)
2002-01-01
Tile Calorimeter modules stored at CERN. The larger modules belong to the Barrel, whereas the smaller ones are for the two Extended Barrels. (The article was about the completion of the 64 modules for one of the latter.) The photo on the first page of the Bulletin n°26/2002, from 24 July 2002, illustrating the article «The ATLAS Tile Calorimeter gets into shape» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.
International Nuclear Information System (INIS)
Actis, S.; Passarino, G.
2006-12-01
In part I and II of this series of papers all elements have been introduced to extend, to two loops, the set of renormalization procedures which are needed in describing the properties of a spontaneously broken gauge theory. In this paper, the final step is undertaken and finite renormalization is discussed. Two-loop renormalization equations are introduced and their solutions discussed within the context of the minimal standard model of fundamental interactions. These equations relate renormalized Lagrangian parameters (couplings and masses) to some input parameter set containing physical (pseudo-)observables. Complex poles for unstable gauge and Higgs bosons are used and a consistent setup is constructed for extending the predictivity of the theory from the Lep1 Z-boson scale (or the Lep2 WW scale) to regions of interest for LHC and ILC physics. (orig.)
BPS Wilson loops and Bremsstrahlung function in ABJ(M): a two loop analysis
Energy Technology Data Exchange (ETDEWEB)
Bianchi, Marco S. [Institut für Physik, Humboldt-Universität zu Berlin,Newtonstraße 15, 12489 Berlin (Germany); Griguolo, Luca [Dipartimento di Fisica e Scienze della Terra, Università di Parmaand INFN Gruppo Collegato di Parma,Viale G.P. Usberti 7/A, 43100 Parma (Italy); Leoni, Matias [Physics Department, FCEyN-UBA & IFIBA-CONICETCiudad Universitaria, Pabellón I, 1428, Buenos Aires (Argentina); Penati, Silvia [Dipartimento di Fisica, Università di Milano-Bicoccaand INFN, Sezione di Milano-Bicocca,Piazza della Scienza 3, I-20126 Milano (Italy); Seminara, Domenico [Dipartimento di Fisica, Università di Firenzeand INFN Sezione di Firenze,via G. Sansone 1, 50019 Sesto Fiorentino (Italy)
2014-06-19
We study a family of circular BPS Wilson loops in N=6 super Chern-Simons-matter theories, generalizing the usual 1/2-BPS circle. The scalar and fermionic couplings depend on two deformation parameters and these operators can be considered as the ABJ(M) counterpart of the DGRT latitudes defined in N=4 SYM. We perform a complete two-loop analysis of their vacuum expectation value, discuss the appearance of framing-like phases and propose a general relation with cohomologically equivalent bosonic operators. We make an all-loop proposal for computing the Bremsstrahlung function associated to the 1/2-BPS cusp in terms of these generalized Wilson loops. When applied to our two-loop result it reproduces the known expression. Finally, we comment on the generalization of this proposal to the bosonic 1/6-BPS case.
Automatic calculation of massive two-loop self-energies with XLOOPS
International Nuclear Information System (INIS)
Franzkowski, J.
1997-01-01
Within the program package XLOOPS it is possible to calculate self-energies up to the two-loop level for arbitrary massive particles. The program package -written in MAPLE (Char et al., Maple V Language Reference Manual (Springer, 1991); Char et al., Maple V Library Reference Manual (Springer, 1991)) - is designed to deal with the full tensor structure of the occurring integrals. This means that applications are not restricted to those cases where the reduction to scalars via equivalence theorem is allowed. The algorithms handle two-loop integrals analytically if this is possible. For those topologies where no analytic result for the general mass case is available, the diagrams are reduced to integral representations which encounter at most at two-fold integration. These integral representations are numerically stable and can be performed easily using VEGAS (Lepage, J. Comp. Phys. 27 (1978) 192; Lepage, Cornell Univ. Preprint CLNS-80/447 (1980)). (orig.)
Matching the $D^{6}R^{4}$ interaction at two-loops
D'Hoker, Eric; Pioline, Boris; Russo, Rodolfo
2015-01-01
The coefficient of the $D^6 {\\cal R}^4$ interaction in the low energy expansion of the two-loop four-graviton amplitude in type II superstring theory is known to be proportional to the integral of the Zhang-Kawazumi (ZK) invariant over the moduli space of genus-two Riemann surfaces. We demonstrate that the ZK invariant is an eigenfunction with eigenvalue 5 of the Laplace-Beltrami operator in the interior of moduli space. Exploiting this result, we evaluate the integral of the ZK invariant explicitly, finding agreement with the value of the two-loop $D^6 {\\cal R}^4$ interaction predicted on the basis of S-duality and supersymmetry. A review of the current understanding of the $D^{2p} {\\cal R}^4$ interactions in type II superstring theory compactified on a torus $T^d$ with $p \\leq 3$ and $d \\leq 4$ is included.
Color-kinematics duality for pure Yang-Mills and gravity at one and two loops
Bern, Zvi; Davies, Scott; Dennen, Tristan; Huang, Yu-tin; Nohle, Josh
2015-08-01
We provide evidence in favor of the conjectured duality between color and kinematics for the case of nonsupersymmetric pure Yang-Mills amplitudes by constructing a form of the one-loop four-point amplitude of this theory that makes the duality manifest. Our construction is valid in any dimension. We also describe a duality-satisfying representation for the two-loop four-point amplitude with identical four-dimensional external helicities. We use these results to obtain corresponding gravity integrands for a theory containing a graviton, dilaton, and antisymmetric tensor, simply by replacing color factors with specified diagram numerators. Using this, we give explicit forms of ultraviolet divergences at one loop in four, six, and eight dimensions, and at two loops in four dimensions.
Energy Technology Data Exchange (ETDEWEB)
Actis, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Passarino, G. [Torino Univ. (Italy). Dipt. di Fisica Teorica; INFN, Sezione di Torino (Italy)
2006-12-15
In part I and II of this series of papers all elements have been introduced to extend, to two loops, the set of renormalization procedures which are needed in describing the properties of a spontaneously broken gauge theory. In this paper, the final step is undertaken and finite renormalization is discussed. Two-loop renormalization equations are introduced and their solutions discussed within the context of the minimal standard model of fundamental interactions. These equations relate renormalized Lagrangian parameters (couplings and masses) to some input parameter set containing physical (pseudo-)observables. Complex poles for unstable gauge and Higgs bosons are used and a consistent setup is constructed for extending the predictivity of the theory from the Lep1 Z-boson scale (or the Lep2 WW scale) to regions of interest for LHC and ILC physics. (orig.)
Two-loop current–current operator contribution to the non-leptonic QCD penguin amplitude
Directory of Open Access Journals (Sweden)
G. Bell
2015-11-01
Full Text Available The computation of direct CP asymmetries in charmless B decays at next-to-next-to-leading order (NNLO in QCD is of interest to ascertain the short-distance contribution. Here we compute the two-loop penguin contractions of the current–current operators Q1,2 and provide a first estimate of NNLO CP asymmetries in penguin-dominated b→s transitions.
Two-loop effective potential for Wess-Zumino model using superfields
International Nuclear Information System (INIS)
Santos, R.P. dos; Srivastava, P.P.
1985-10-01
For the case of several interacting chiral superfields the propagators for the unconstrained superfield potentials in the 'shifted' theory, where the supersymmetry is explicitly broken, are derived in a compact form. They are used to compute one-loop effective potential in the general case, while a superfield calculation of renormalized effective potential to two loops for the Wess-Zumino model is performed. (author)
Uncertainty of the two-loop RG upper bound on the Higgs mass
International Nuclear Information System (INIS)
Pirogov, Yu.F.; Zenin, O.V.
2003-01-01
A modified criterion of the standard model perturbative consistency is proposed. It is based on the analytic properties of the two-loop standard model running couplings. Under the criterion adopted, the Higgs mass up to 380 GeV might not give rise to the strong coupling prior to the Planck scale. This means that light Higgs boson is possibly preferred for reasons other than the standard model perturbative consistency, i.e., for reasons beyond the standard model [ru
Uncertainty of the two-loop RG upper bound on the Higgs mass
International Nuclear Information System (INIS)
Pirogov, Yu.F.; Zenin, O.V.
2003-01-01
A modified criterion of the SM perturbative consistency is proposed. It is based on the analytic properties of the two-loop SM running couplings. Under the criterion adopted, the Higgs mass up to 380 GeV might not give rise to strong coupling prior to the Planck scale. This means that the light Higgs boson is possibly preferred for reasons other than the SM perturbative consistency, i.e., for reasons beyond the SM
Energy Technology Data Exchange (ETDEWEB)
Actis, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Passarino, G. [Torino Univ. (Italy). Dipt. di Fisica Teorica; INFN, Sezione di Torino (Italy)
2006-12-15
In part I general aspects of the renormalization of a spontaneously broken gauge theory have been introduced. Here, in part II, two-loop renormalization is introduced and discussed within the context of the minimal Standard Model. Therefore, this paper deals with the transition between bare parameters and fields to renormalized ones. The full list of one- and two-loop counterterms is shown and it is proven that, by a suitable extension of the formalism already introduced at the one-loop level, two-point functions suffice in renormalizing the model. The problem of overlapping ultraviolet divergencies is analyzed and it is shown that all counterterms are local and of polynomial nature. The original program of 't Hooft and Veltman is at work. Finite parts are written in a way that allows for a fast and reliable numerical integration with all collinear logarithms extracted analytically. Finite renormalization, the transition between renormalized parameters and physical (pseudo-)observables, are discussed in part III where numerical results, e.g. for the complex poles of the unstable gauge bosons, are shown. An attempt is made to define the running of the electromagnetic coupling constant at the two-loop level. (orig.)
Directory of Open Access Journals (Sweden)
2012-01-01
Full Text Available Regarding Gorelik, G., & Shackelford, T.K. (2011. Human sexual conflict from molecules to culture. Evolutionary Psychology, 9, 564–587: The authors wish to correct an omission in citation to the existing literature. In the final paragraph on p. 570, we neglected to cite Burch and Gallup (2006 [Burch, R. L., & Gallup, G. G., Jr. (2006. The psychobiology of human semen. In S. M. Platek & T. K. Shackelford (Eds., Female infidelity and paternal uncertainty (pp. 141–172. New York: Cambridge University Press.]. Burch and Gallup (2006 reviewed the relevant literature on FSH and LH discussed in this paragraph, and should have been cited accordingly. In addition, Burch and Gallup (2006 should have been cited as the originators of the hypothesis regarding the role of FSH and LH in the semen of rapists. The authors apologize for this oversight.
2002-01-01
The photo on the second page of the Bulletin n°48/2002, from 25 November 2002, illustrating the article «Spanish Visit to CERN» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption. The Spanish delegation, accompanied by Spanish scientists at CERN, also visited the LHC superconducting magnet test hall (photo). From left to right: Felix Rodriguez Mateos of CERN LHC Division, Josep Piqué i Camps, Spanish Minister of Science and Technology, César Dopazo, Director-General of CIEMAT (Spanish Research Centre for Energy, Environment and Technology), Juan Antonio Rubio, ETT Division Leader at CERN, Manuel Aguilar-Benitez, Spanish Delegate to Council, Manuel Delfino, IT Division Leader at CERN, and Gonzalo León, Secretary-General of Scientific Policy to the Minister.
Directory of Open Access Journals (Sweden)
2014-01-01
Full Text Available Regarding Tagler, M. J., and Jeffers, H. M. (2013. Sex differences in attitudes toward partner infidelity. Evolutionary Psychology, 11, 821–832: The authors wish to correct values in the originally published manuscript. Specifically, incorrect 95% confidence intervals around the Cohen's d values were reported on page 826 of the manuscript where we reported the within-sex simple effects for the significant Participant Sex × Infidelity Type interaction (first paragraph, and for attitudes toward partner infidelity (second paragraph. Corrected values are presented in bold below. The authors would like to thank Dr. Bernard Beins at Ithaca College for bringing these errors to our attention. Men rated sexual infidelity significantly more distressing (M = 4.69, SD = 0.74 than they rated emotional infidelity (M = 4.32, SD = 0.92, F(1, 322 = 23.96, p < .001, d = 0.44, 95% CI [0.23, 0.65], but there was little difference between women's ratings of sexual (M = 4.80, SD = 0.48 and emotional infidelity (M = 4.76, SD = 0.57, F(1, 322 = 0.48, p = .29, d = 0.08, 95% CI [−0.10, 0.26]. As expected, men rated sexual infidelity (M = 1.44, SD = 0.70 more negatively than they rated emotional infidelity (M = 2.66, SD = 1.37, F(1, 322 = 120.00, p < .001, d = 1.12, 95% CI [0.85, 1.39]. Although women also rated sexual infidelity (M = 1.40, SD = 0.62 more negatively than they rated emotional infidelity (M = 2.09, SD = 1.10, this difference was not as large and thus in the evolutionary theory supportive direction, F(1, 322 = 72.03, p < .001, d = 0.77, 95% CI [0.60, 0.94].
Mihaila, L.
2009-10-01
The two-loop relations between the running gluino-quark-squark coupling, the gluino and the quark mass defined in dimensional regularization (DREG) and dimensional reduction (DRED) in the framework of SUSY-QCD are presented. Furthermore, we verify with the help of these relations that the three-loop β-functions derived in the minimal subtraction scheme combined with DREG or DRED transform into each other. This result confirms the equivalence of the two schemes at the three-loop order, if applied to SUSY-QCD.
Improved two-loop beam energy stabilizer for an FN tandem accelerator
International Nuclear Information System (INIS)
Trainor, T.A.
1981-01-01
A detailed analysis of the properties of various elements in a two-loop voltage regulator for a tandem accelerator enabled design of an optimum system which reduces effective accelerating voltage noise below 100 V. Essential features of the new system are high-quality slit preamplifiers, careful attention to removal of extraneous noise sources, and proper shaping of frequency responses to maximize stable gains and ensure compatibility of the two control loops. The resultant beam energy stabilizer system is easy to operate, has well defined indicators for proper adjustment of operating parameters, and recovers reliably from beam interruptions
New two-loop contribution to electric dipole moment in supersymmetric theories
Chang, Darwin; Pilaftsis, Apostolos; Chang, Darwin; Keung, Wai-Yee; Pilaftsis, Apostolos
1999-01-01
We calculate a new type of two-loop contributions to the electric dipole moments of the electron and neutron in supersymmetric theories. The new contributions are originated from the potential CP violation in the trilinear couplings of the Higgs bosons to the scalar-top or the scalar-bottom quarks. These couplings were previously very weakly constrained. The electric dipole moments are induced through a mechanism analogous to that due to Barr and Zee. We find observable effects for a sizeable portion of the parameter space related to the third generation scalar-quarks in the minimal supersymmetric standard model which cannot be excluded by earlier considerations.
Reformulating the TBA equations for the quark anti-quark potential and their two loop expansion
International Nuclear Information System (INIS)
Bajnok, Zoltán; Balog, János; Correa, Diego H.; Hegedűs, Árpád; Massolo, Fidel I. Schaposnik; Tóth, Gábor Zsolt
2014-01-01
The boundary thermodynamic Bethe Ansatz (BTBA) equations introduced in http://dx.doi.org/10.1007/JHEP08(2012)134http://dx.doi.org/10.1007/JHEP10(2013)135 to describe the cusp anomalous dimension contain imaginary chemical potentials and singular boundary fugacities, which make its systematic expansion problematic. We propose an alternative formulation based on real chemical potentials and additional source terms. We expand our equations to double wrapping order and find complete agreement with the direct two-loop gauge theory computation of the cusp anomalous dimension
Two-loop snail diagrams: relating neutrino masses to dark matter
Energy Technology Data Exchange (ETDEWEB)
Farzan, Yasaman [Physics school, Institute for Research in Fundamental Sciences (IPM),P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
2015-05-06
Various mechanisms have been developed to explain the origin of neutrino masses. One of them is radiative mass generation. Two-loop mass generation is of particular interest because the masses and couplings of new particles propagating in the loop can be in the range testable by other experiments and observations. In order for the radiative mass suppression to be reliable, it should be guaranteed that lower loop contributions are suppressed. Based on loop topology and the form of electroweak presentation of the particles propagating in the loop, one can determine whether a lower — and therefore dominant — loop contribution is possible. We present a model based on these general considerations which leads to neutrino masses via a two-loop diagram which we dub as “snail-diagram”. The model has two natural candidates for dark matter one of them being a neutral Dirac fermion which can satisfy the conditions of the thermal freeze-out scenario by annihilation to lepton pairs. We comment on the possibility of explaining the GeV gamma ray excess observed by Fermi-LAT from the region close to the Galaxy Center. We also discuss possible signals at the LHC and at experiments searching for lepton flavor violating rare decays.
Two-loop snail diagrams: relating neutrino masses to dark matter
Farzan, Yasaman
2015-05-01
Various mechanisms have been developed to explain the origin of neutrino masses. One of them is radiative mass generation. Two-loop mass generation is of particular interest because the masses and couplings of new particles propagating in the loop can be in the range testable by other experiments and observations. In order for the radiative mass suppression to be reliable, it should be guaranteed that lower loop contributions are suppressed. Based on loop topology and the form of electroweak presentation of the particles propagating in the loop, one can determine whether a lower — and therefore dominant — loop contribution is possible. We present a model based on these general considerations which leads to neutrino masses via a two-loop diagram which we dub as "snail-diagram". The model has two natural candidates for dark matter one of them being a neutral Dirac fermion which can satisfy the conditions of the thermal freeze-out scenario by annihilation to lepton pairs. We comment on the possibility of explaining the GeV gamma ray excess observed by Fermi-LAT from the region close to the Galaxy Center. We also discuss possible signals at the LHC and at experiments searching for lepton flavor violating rare decays.
Testing SUSY at the LHC: Electroweak and Dark matter fine tuning at two-loop order
Cassel, S; Ross, G G
2010-01-01
In the framework of the Constrained Minimal Supersymmetric Standard Model (CMSSM) we evaluate the electroweak fine tuning measure that provides a quantitative test of supersymmetry as a solution to the hierarchy problem. Taking account of current experimental constraints we compute the fine tuning at two-loop order and determine the limits on the CMSSM parameter space and the measurements at the LHC most relevant in covering it. Without imposing the LEPII bound on the Higgs mass, it is shown that the fine tuning computed at two-loop has a minimum $\\Delta=8.8$ corresponding to a Higgs mass $m_h=114\\pm 2$ GeV. Adding the constraint that the SUSY dark matter relic density should be within present bounds we find $\\Delta=15$ corresponding to $m_h=114.7\\pm 2$ GeV and this rises to $\\Delta=17.8$ ($m_h=115.9\\pm 2$ GeV) for SUSY dark matter abundance within 3$\\sigma$ of the WMAP constraint. We extend the analysis to include the contribution of dark matter fine tuning. In this case the overall fine tuning and Higgs mas...
Borowka, Sophia; Weiglein, Georg
Higher-order corrections to the Higgs-boson masses within the MSSM are desirable for accurate predictions currently testable at the LHC. From the comparison of the prediction with the measured value of the mass of the discovered Higgs signal, constraints on the available parameter space can be inferred. In order to improve on the accuracy of current predictions, all two-loop corrections involving the strong coupling are computed for the Higgs-boson mass spectrum of the MSSM with complex parameters. Apart from the dependence on the strong coupling, these contributions depend on the weak coupling, leading to terms of $\\mathcal{O}{\\left(\\alpha\\alpha_s\\right)}$, or on Yukawa couplings, leading to terms of $\\mathcal{O}{\\left(\\sqrt{\\alpha_{q_1}}\\sqrt{\\alpha_{q_2}}\\alpha_s\\right)}$, ($q_{1,2}=t,b,c,s,u,d$; flavor-violation effects are neglected). The full dependence on the external momentum at the two-loop level and on all relevant mass scales is taken into account. The calculation is performed in the Feynman-diagra...
Leibbrandt, George; Leibbrandt, George; Williams, Jimmy D.
2000-01-01
The complete two-loop correction to the quark propagator, consisting of the spider, rainbow, gluon bubble and quark bubble diagrams, is evaluated in the noncovariant light-cone gauge (lcg). (The overlapping self-energy diagram had already been computed.) The chief technical tools include the powerful matrix integration technique, the n^*-prescription for the spurious poles of 1/qn, and the detailed analysis of the boundary singularities in five- and six-dimensional parameter space. It is shown that the total divergent contribution to the two-loop correction Sigma_2 contains both covariant and noncovariant components, and is a local function of the external momentum p, even off the mass-shell, as all nonlocal divergent terms cancel exactly. Consequently, both the quark mass and field renormalizations are local. The structure of Sigma_2 implies a quark mass counterterm of the form $\\delta m (lcg) = m\\tilde\\alpha_s C_F(3+\\tilde\\alpha_sW) + {\\rm O} (\\tilde\\alpha_s^3)$, the dimensional regulator epsilon, and on th...
Leibbrandt, G
2000-01-01
For pt.I see ibid., vol.440, p.537-602, 1995. The complete two-loop correction to the quark propagator, consisting of the spider, rainbow, gluon bubble and quark bubble diagrams, is evaluated in the non-covariant light-cone gauge (LCG), n.A/sup a/(x)=0, n/sup 2/=0. (The overlapping self-energy diagram had already been computed.) The chief technical tools include the powerful matrix integration technique, the n*/sub mu /-prescription for the spurious poles of (q.n)/sup -1/, and the detailed analysis of the boundary singularities in five- and six-dimensional parameter space. It is shown that the total divergent contribution to the two-loop correction Sigma /sub 2/ contains both covariant and non-covariant components, and is a local function of the external momentum p, even off the mass-shell, as all non-local divergent terms cancel exactly. Consequently, both the quark mass and field renormalizations are local. The structure of Sigma /sub 2/ implies a quark mass counterterm of the form delta m(LCG)=m alpha /sub...
Yang, Jingyu; Lin, Jiahui; Liu, Yuejun; Yang, Kang; Zhou, Lanwei; Chen, Guoping
2017-08-01
It is well known that intelligent control theory has been used in many research fields, novel modeling method (DROMM) is used for flexible rectangular active vibration control, and then the validity of new model is confirmed by comparing finite element model with new model. In this paper, taking advantage of the dynamics of flexible rectangular plate, a two-loop sliding mode (TSM) MIMO approach is introduced for designing multiple-input multiple-output continuous vibration control system, which can overcome uncertainties, disturbances or unstable dynamics. An illustrative example is given in order to show the feasibility of the method. Numerical simulations and experiment confirm the effectiveness of the proposed TSM MIMO controller.
The Higgs Mass in the MSSM at two-loop order beyond minimal flavour violation
Goodsell, Mark D; Staub, Florian
2016-01-01
Soft supersymmetry-breaking terms provide a wealth of new potential sources of flavour violation, which lead to very tight constraints from precision experiments. This has posed a challenge to construct flavour models to both explain the structure of the Standard Model Yukawa couplings and how their consequent predictions for patterns in the soft supersymmetry-breaking terms do not violate these constraints. While such models have been studied in great detail, the impact of flavour violating soft terms on the Higgs mass at the two-loop level has been assumed to be small or negligible. In this letter, we show that large flavour violation in the up-squark sector can give a positive or negative shift to the SM-like Higgs of several GeV, without being in conflict with any other observation. We investigate in which regions of the parameter space these effects can be expected.
International Nuclear Information System (INIS)
Martin, Stephen P.
2003-01-01
I present a method for accurately calculating the pole mass of the lightest Higgs scalar boson in supersymmetric extensions of the standard model, using a mass-independent renormalization scheme. The Higgs scalar self-energies are approximated by supplementing the exact one-loop results with the second derivatives of the complete two-loop effective potential in Landau gauge. I discuss the dependence of this approximation on the choice of renormalization scale, and note the existence of particularly poor choices, which fortunately can be easily identified and avoided. For typical input parameters, the variation in the calculated Higgs boson mass over a wide range of renormalization scales is found to be of the order of a few hundred MeV or less, and is significantly improved over previous approximations
Numerical integration of massive two-loop Mellin-Barnes integrals in Minkowskian regions
International Nuclear Information System (INIS)
Dubovyk, Ievgen
2016-07-01
Mellin-Barnes (MB) techniques applied to integrals emerging in particle physics perturbative calculations are summarized. New versions of AMBRE packages which construct planar and nonplanar MB representations are shortly discussed. The numerical package MBnumerics.m is presented for the first time which is able to calculate with a high precision multidimensional MB integrals in Minkowskian regions. Examples are given for massive vertex integrals which include threshold effects and several scale parameters.
Evidence for two-loop interaction from IRIS and SDO observations of penumbral brightenings
Alissandrakis, C. E.; Koukras, A.; Patsourakos, S.; Nindos, A.
2017-07-01
Aims: We investigate small scale energy release events which can provide clues on the heating mechanism of the solar corona. Methods: We analyzed spectral and imaging data from the Interface Region Imaging Spectrograph (IRIS), images from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatoty (SDO), and magnetograms from the Helioseismic and Magnetic Imager (HMI) aboard SDO. Results: We report observations of small flaring loops in the penumbra of a large sunspot on July 19, 2013. Our main event consisted of a loop spanning 15'', from the umbral-penumbral boundary to an opposite polarity region outside the penumbra. It lasted approximately 10 min with a two minute impulsive peak and was observed in all AIA/SDO channels, while the IRIS slit was located near its penumbral footpoint. Mass motions with an apparent velocity of 100 km s-1 were detected beyond the brightening, starting in the rise phase of the impulsive peak; these were apparently associated with a higher-lying loop. We interpret these motions in terms of two-loop interaction. IRIS spectra in both the C II and Si iv lines showed very extended wings, up to about 400 km s-1, first in the blue (upflows) and subsequently in the red wing. In addition to the strong lines, emission was detected in the weak lines of Cl I, O I and C I, as well as in the Mg II triplet lines. Absorption features in the profiles of the C II doublet, the Si iv doublet and the Mg II h and k lines indicate the existence of material with a lower source function between the brightening and the observer. We attribute this absorption to the higher loop and this adds further credibility to the two-loop interaction hypothesis. Tilts were detected in the absorption spectra, as well as in the spectra of Cl I, O I, and C I lines, possibly indicating rotational motions from the untwisting of magnetic flux tubes. Conclusions: We conclude that the absorption features in the C II, Si iv and Mg II profiles originate in a higher
Tuning supersymmetric models at the LHC: A comparative analysis at two-loop level
Ghilencea, D M; Park, M
2012-01-01
We provide a comparative study of the fine tuning amount (Delta) at the two-loop leading log level in supersymmetric models commonly used in SUSY searches at the LHC. These are the constrained MSSM (CMSSM), non-universal Higgs masses models (NUHM1, NUHM2), non-universal gaugino masses model (NUGM) and GUT related gaugino masses models (NUGMd). Two definitions of the fine tuning are used, the first (Delta_{max}) measures maximal fine-tuning wrt individual parameters while the second (Delta_q) adds their contribution in "quadrature". As a direct result of two theoretical constraints (the EW minimum conditions), fine tuning (Delta_q) emerges as a suppressing factor (effective prior) of the averaged likelihood (under the priors), under the integral of the global probability of measuring the data (Bayesian evidence p(D)). For each model, there is little difference between Delta_q, Delta_{max} in the region allowed by the data, with similar behaviour as functions of the Higgs, gluino, stop mass or SUSY scale (m_{su...
Two-loop supersymmetric QCD and half-maximal supergravity amplitudes
Johansson, Henrik; Kälin, Gregor; Mogull, Gustav
2017-09-01
Using the duality between color and kinematics, we construct two-loop four-point scattering amplitudes in N=2 super-Yang-Mills (SYM) theory coupled to N f fundamental hypermultiplets. Our results are valid in D ≤ 6 dimensions, where the upper bound corresponds to six-dimensional chiral N=(1,0) SYM theory. By exploiting a close connection with N=4 SYM theory — and, equivalently, six-dimensional N=(1,1) SYM theory — we find compact integrands with four-dimensional external vectors in both the maximally-helicity-violating (MHV) and all-chiral-vector sectors. Via the double-copy construction corresponding D-dimensional half-maximal supergravity amplitudes with external graviton multiplets are obtained in the MHV and all-chiral sectors. Appropriately tuning N f enables us to consider both pure and matter-coupled supergravity, with arbitrary numbers of vector multiplets in D = 4. As a bonus, we obtain the integrands of the genuinely six-dimensional supergravities with N=(1,1) and N=(2,0) supersymmetry. Finally, we extract the potential ultraviolet divergence of half-maximal supergravity in D = 5 - 2 ɛ and show that it non-trivially cancels out as expected.
Planar amplitudes in maximally supersymmetric Yang-Mills theory.
Anastasiou, C; Dixon, L; Bern, Z; Kosower, D A
2003-12-19
The collinear factorization properties of two-loop scattering amplitudes in dimensionally regulated N=4 super-Yang-Mills theory suggest that, in the planar ('t Hooft) limit, higher-loop contributions can be expressed entirely in terms of one-loop amplitudes. We demonstrate this relation explicitly for the two-loop four-point amplitude and, based on the collinear limits, conjecture an analogous relation for n-point amplitudes. The simplicity of the relation is consistent with intuition based on the anti-de Sitter/conformal field theory correspondence that the form of the large-N(c) L-loop amplitudes should be simple enough to allow a resummation to all orders.
International Nuclear Information System (INIS)
Metsaev, R.R.; Tseytlin, A.A.
1987-01-01
We prove the on-shell equivalence of the order α' terms in the string effective equations (for the graviton, dilaton and the antisymmetric tensor) to the vanishing of the corresponding (two-loop) terms in the Weyl anomaly coefficients for the general bosonic σ-model. We first determine the α' term in the string effective action starting with the known expression for the 3- and 4-point string amplitudes. Then we compute the two-loop β-function in the general σ-model with the antisymmetric tensor coupling. Special emphasis is made on the renormalization scheme dependence of the β-function. Our result disagrees with the previously known one and cannot be manifestly expressed in terms of the generalized curvature for the connection with torsion. We also prove (to the order α' 2 ) that the parallelizable spaces are solutions of the string equations of motion and establish the complete 3-loop expression for the 'central charge' coefficient. (orig.)
On the two-loop divergences of the 2-point hypermultiplet supergraphs for 6D, N = (1 , 1) SYM theory
Buchbinder, I. L.; Ivanov, E. A.; Merzlikin, B. S.; Stepanyantz, K. V.
2018-03-01
We consider 6D, N = (1 , 1) supersymmetric Yang-Mills theory formulated in N = (1 , 0) harmonic superspace and analyze the structure of the two-loop divergences in the hypermultiplet sector. Using the N = (1 , 0) superfield background field method we study the two-point supergraphs with the hypermultiplet legs and prove that their total contribution to the divergent part of effective action vanishes off shell.
Two-loop coupling constant renormalization in lattice SU(N)xSU(N) 2D chiral models
Energy Technology Data Exchange (ETDEWEB)
Magnoli, N.; Ravanini, F.
1986-08-01
For the most general link action of lattice SU(N)xSU(N) two dimensional chiral models, the two loop coupling constant renormalization is discussed in the context of the background field method. A non-linear reparametrization of the fields, necessary to keep the invariance of the theory, introduces unpleasant extra-terms. However some of the non-universal contributions are unaffected by these extra-terms and can be easily calculated. This allows to compute the difference between the first non-universal coefficients of the Callan-Symanzik beta functions for two actions having the same scale ..lambda...
Two-loop helicity amplitudes for the production of two off-shell electroweak bosons in gluon fusion
Caola, Fabrizio; Melnikov, Kirill; Smirnov, Alexander V.; Smirnov, Vladimir A.
2015-01-01
We compute the part of the two-loop virtual amplitude for the process $gg \\to V_1 V_2 \\to (l_1 \\bar l'_{1}) (l_2 \\bar l'_2)$, where $V_{1,2}$ are arbitrary electroweak gauge bosons, that receives contributions from loops of massless quarks. Invariant masses of electroweak bosons are allowed to be different from each other. Our result provides an important ingredient for improving the description of gluon fusion contribution to the production of four-lepton final states at the LHC.
International Nuclear Information System (INIS)
Beneke, M.; Falgari, P.; Schwinn, C.
2010-01-01
We consider the total production cross section of heavy coloured particle pairs in hadronic collisions at the production threshold. We construct a basis in colour space that diagonalizes to all orders in perturbation theory the soft function, which appears in a new factorization formula for the combined resummation of soft gluon and Coulomb gluon effects. This extends recent results on the structure of soft anomalous dimensions and allows us to determine an analytic expression for the two-loop soft anomalous dimension at threshold for all production processes of interest.
Planar quark diagrams and binary spin processes
International Nuclear Information System (INIS)
Grigoryan, A.A.; Ivanov, N.Ya.
1986-01-01
Contributions of planar diagrams to the binary scattering processes are analyzed. The analysis is based on the predictions of quark-gluon picture of strong interactions for the coupling of reggeons with quarks as well as on the SU(6)-classification of hadrons. The dependence of contributions of nonplanar corrections on spins and quark composition of interacting particles is discussed
Energy Technology Data Exchange (ETDEWEB)
Mohanty, Subhasish [Argonne National Lab. (ANL), Argonne, IL (United States); Soppet, William [Argonne National Lab. (ANL), Argonne, IL (United States); Majumdar, Saurin [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, Ken [Argonne National Lab. (ANL), Argonne, IL (United States)
2015-01-03
This report provides an update on an assessment of environmentally assisted fatigue for light water reactor components under extended service conditions. This report is a deliverable in April 2015 under the work package for environmentally assisted fatigue under DOE's Light Water Reactor Sustainability program. In this report, updates are discussed related to a system level preliminary finite element model of a two-loop pressurized water reactor (PWR). Based on this model, system-level heat transfer analysis and subsequent thermal-mechanical stress analysis were performed for typical design-basis thermal-mechanical fatigue cycles. The in-air fatigue lives of components, such as the hot and cold legs, were estimated on the basis of stress analysis results, ASME in-air fatigue life estimation criteria, and fatigue design curves. Furthermore, environmental correction factors and associated PWR environment fatigue lives for the hot and cold legs were estimated by using estimated stress and strain histories and the approach described in NUREG-6909. The discussed models and results are very preliminary. Further advancement of the discussed model is required for more accurate life prediction of reactor components. This report only presents the work related to finite element modelling activities. However, in between multiple tensile and fatigue tests were conducted. The related experimental results will be presented in the year-end report.
Constraints on abelian extensions of the Standard Model from two-loop vacuum stability and U(1) B- L
Corianò, Claudio; Rose, Luigi Delle; Marzo, Carlo
2016-02-01
We present a renormalization group study of the scalar potential in a minimal U(1) B- L extension of the Standard Model involving one extra heavier Higgs and three heavy right-handed neutrinos with family universal B-L charge assignments. We implement a type-I seesaw for the masses of the light neutrinos of the Standard Model. In particular, compared to a previous study, we perform a two-loop extension of the evolution, showing that two-loop effects are essential for the study of the stability of the scalar potential up to the Planck scale. The analysis includes the contribution of the kinetic mixing between the two abelian gauge groups, which is radiatively generated by the evolution, and the one-loop matching conditions at the electroweak scale. By requiring the stability of the potential up to the Planck mass, significant constraints on the masses of the heavy neutrinos, on the gauge couplings and the mixing in the Higgs sector are identified.
Analytic two-loop results for self-energy- and vertex-type diagrams with one non-zero mass
International Nuclear Information System (INIS)
Fleischer, J.; Kotikov, A.V.; Veretin, O.L.
1999-01-01
For a large class of two-loop self-energy- and vertex-type diagrams with only one non-zero mass (m) and the vertices also with only one non-zero external momentum squared (q 2 ) the first few expansion coefficients are calculated by the large mass expansion. This allows us to 'guess' the general structure of these coefficients and to verify them in terms of certain classes of 'basis elements', which are essentially harmonic sums. Since for this case with only one non-zero mass the large mass expansion and the Taylor series in terms of q 2 are identical, this approach yields analytic expressions of the Taylor coefficients, from which the diagram can be easily evaluated numerically in a large domain of the complex q 2 -plane by well known methods. It is also possible to sum the Taylor series and present the results in terms of polylogarithms
On the Kählerian symmetries of the two-loop action of the effective string theory
Ozkurt, S S
2003-01-01
Sometimes ago, it has been proposed in a paper by N.Kaloper and K.A.Meissner (\\PR {\\bf D56} (1997) 7940) that if one makes local redefinitions of fields, it does not change the equations of motion (in the redefined fields); however, this comment has not generally been accepted, namely, the redefined fields satisfy different equations of motion. For this reason, in this paper, it is proved that the whole action can be written as a square of the zeroth-order field equations. In this way, we show that any solution of the zeroth-order field equations, which has some K\\"{a}hler symmetry, at the same time, is also a solution of the two-loop equations.
Directory of Open Access Journals (Sweden)
Zhen Liu
2017-02-01
Full Text Available We extend some two Higgs doublet models, where the Yukawa couplings for the charged fermion mass generation only involve one Higgs doublet, by two singlet scalars respectively carrying a singly electric charge and a doubly electric charge. The doublet and singlet scalars together can mediate a two-loop diagram to generate a tiny Majorana mass matrix of the standard model neutrinos. Remarkably, the structure of the neutrino mass matrix is fully determined by the symmetric Yukawa couplings of the doubly charged scalar to the right-handed leptons. Meanwhile, a one-loop induced neutrinoless double beta decay can arrive at a testable level even if the electron neutrino has an extremely small Majorana mass. We also study other experimental constraints and implications including some rare processes and Higgs phenomenology.
A New Technique for Reducing Size of a WPT System Using Two-Loop Strongly-Resonant Inductors
Directory of Open Access Journals (Sweden)
Matjaz Rozman
2017-10-01
Full Text Available Mid-range resonant coupling-based high efficient wireless power transfer (WPT techniques have gained substantial research interest due to the number of potential applications in many industries. This paper presents a novel design of a resonant two-loop WPT technique including the design, fabrication and preliminary results of this proposal. This new design employs a compensation inductor which is combined with the transmitter and receiver loops in order to significantly scale down the size of the transmitter and receiver coils. This can improve the portability of the WPT transmitters in practical systems. Moreover, the benefits of the system enhancement are not only limited to the lessened magnitude of the T X & R X , simultaneously both the weight and the bill of materials are also minimised. The proposed system also demonstrates compatibility with the conventional electronic components such as capacitors hence the development of the T X & R X is simplified. The proposed system performance has been validated using the similarities between the experimental and simulation results. The power efficiency of the prototype circuit is found to be 93%, which is close to the efficiency reached by the conventional design. However, the weight of the transmitter and receiver inductors is now reduced by 78%, while the length of these inductors is reduced by 80%.
Marel, Gérard; Bréhin, S; Devaux, B; Diamant-Berger, Alain M; Leschevin, C; Maillard, J; Malbequi, Y; Martin, H; Patoux, A; Pelle, J; Plancoulaine, J; Tarte, Gérard; Turlay, René
1977-01-01
The authors describe 14 m/sup 2/ hexagonal planar drift chambers designed for the neutrino experiment of the CERN-Dortmund-Heidelberg- Saclay Collaboration. Details on mechanical construction, electronic read-out, results on efficiency and accuracy are presented. (6 refs).
DEFF Research Database (Denmark)
Brodal, Gerth Stølfting; Jacob, Rico
2002-01-01
In this paper we determine the computational complexity of the dynamic convex hull problem in the planar case. We present a data structure that maintains a finite set of n points in the plane under insertion and deletion of points in amortized O(log n) time per operation. The space usage of the d...
Energy Technology Data Exchange (ETDEWEB)
Chankowski, Piotr H. [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,Pasteura 5, 02-093 Warsaw (Poland); Lewandowski, Adrian [Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut),Mühlenberg 1, D-14476 Potsdam (Germany); Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,Pasteura 5, 02-093 Warsaw (Poland); Meissner, Krzysztof A. [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,Pasteura 5, 02-093 Warsaw (Poland)
2016-11-18
We perform a systematic one-loop renormalization of a general renormalizable Yang-Mills theory coupled to scalars and fermions using a regularization scheme with a smooth momentum cutoff Λ (implemented through an exponential damping factor). We construct the necessary finite counterterms restoring the BRST invariance of the effective action by analyzing the relevant Slavnov-Taylor identities. We find the relation between the renormalized parameters in our scheme and in the conventional (MS)-bar scheme which allow us to obtain the explicit two-loop renormalization group equations in our scheme from the known two-loop ones in the (MS)-bar scheme. We calculate in our scheme the divergences of two-loop vacuum graphs in the presence of a constant scalar background field which allow us to rederive the two-loop beta functions for parameters of the scalar potential. We also prove that consistent application of the proposed regularization leads to counterterms which, together with the original action, combine to a bare action expressed in terms of bare parameters. This, together with treating Λ as an intrinsic scale of a hypothetical underlying finite theory of all interactions, offers a possibility of an unconventional solution to the hierarchy problem if no intermediate scales between the electroweak scale and the Planck scale exist.
Chankowski, Piotr H.; Lewandowski, Adrian; Meissner, Krzysztof A.
2016-11-01
We perform a systematic one-loop renormalization of a general renormalizable Yang-Mills theory coupled to scalars and fermions using a regularization scheme with a smooth momentum cutoff Λ (implemented through an exponential damping factor). We construct the necessary finite counterterms restoring the BRST invariance of the effective action by analyzing the relevant Slavnov-Taylor identities. We find the relation between the renormalized parameters in our scheme and in the conventional overline{MS} scheme which allow us to obtain the explicit two-loop renormalization group equations in our scheme from the known two-loop ones in the overline{MS} scheme. We calculate in our scheme the divergences of two-loop vacuum graphs in the presence of a constant scalar background field which allow us to rederive the two-loop beta functions for parameters of the scalar potential. We also prove that consistent application of the proposed regularization leads to counterterms which, together with the original action, combine to a bare action expressed in terms of bare parameters. This, together with treating Λ as an intrinsic scale of a hypothetical underlying finite theory of all interactions, offers a possibility of an unconventional solution to the hierarchy problem if no intermediate scales between the electroweak scale and the Planck scale exist.
Directory of Open Access Journals (Sweden)
B. V. Yakovlev
2007-01-01
Full Text Available An analysis of influence of initial parameters and fuel afterburning ratio on efficiency of single- and two-loop combined-cycle plant has been done in the paper.The paper contains fundamentals of combined-cycle plants initial parameters’ optimization and examples for the sets with gas turbines of various efficiency.
Planar metasurface retroreflector
Arbabi, Amir; Arbabi, Ehsan; Horie, Yu; Kamali, Seyedeh Mahsa; Faraon, Andrei
2017-07-01
Metasurfaces are two-dimensional arrangements of subwavelength scatterers that control the propagation of optical waves. Here, we show that cascaded metasurfaces, each performing a predefined mathematical transformation, provide a new optical design framework that enables new functionalities not yet demonstrated with single metasurfaces. Specifically, we demonstrate that retroreflection can be achieved with two vertically stacked planar metasurfaces, the first performing a spatial Fourier transform and its inverse, and the second imparting a spatially varying momentum to the Fourier transform of the incident light. Using this concept, we fabricate and test a planar monolithic near-infrared retroreflector composed of two layers of silicon nanoposts, which reflects light along its incident direction with a normal incidence efficiency of 78% and a large half-power field of view of 60°. The metasurface retroreflector demonstrates the potential of cascaded metasurfaces for implementing novel high-performance components, and enables low-power and low-weight passive optical transmitters.
Bason, Y.; Klein, L.; Yau, J. -B.; Hong, X.; Hoffman, J.; Ahn, C. H.
2005-01-01
We suggest a new type of magnetic random access memory (MRAM) that is based on the phenomenon of the planar Hall effect (PHE) in magnetic films, and we demonstrate this idea with manganite films. The PHE-MRAM is structurally simpler than currently developed MRAM that is based on magnetoresistance tunnel junctions (MTJ), with the tunnel junction structure being replaced by a single layer film.
Kesselgruber, Martin
2001-01-01
The element of planar chirality turned out to be of special importance to achieve high enantioselectivities in various asymmetric processes. In the course of this PhD thesis, the sulfoximine unit was established as a new chiral ortho-directing group for ferrocenes. By variation of the metal fragment and other structural properties of a published chiral ligand, a cyclopentadienylrhenium(I)tricarbonyl complex was identified as more selective than the original ferrocene system in the asymmetric ...
International Nuclear Information System (INIS)
Haste, T.J.; Birchley, J.; Richner, M.
2010-01-01
Operation of pressurised water reactors involves shutdown periods for refuelling and maintenance. In preparation for this, the reactor system is cooled down, depressurised and partially drained. Although reactor coolant pressure is lower than during full-power operation, there remains the possibility of a loss-of-coolant accident (LOCA), with a certain but low probability. While the decay heat to be removed is lower than that from a LOCA at full power, the reduced availability of safety systems implies a risk of failing to maintain core cooling, and hence of core damage. This is recognised though probabilistic safety analyses (PSA), which identify low but non-negligible contributions to core damage frequency from accidents during cooldown and shutdown. Analyses are made for a typical two-loop Westinghouse PWR of the consequences of a range of LOCAs during hot and intermediate shutdown, 4 and 5 h after reactor shutdown respectively. The accumulators are isolated, while power to some of the pumped safety injection systems (SIs) is racked out. The study assesses the effectiveness of the nominally assumed SIs in restoring coolant inventory and preventing core damage, and the margin against core damage where their actuation is delayed. The calculations use the engineering-level MELCOR1.8.5 code, supplemented by the SCDAPSIM and SCDAP/RELAP5 codes, which provide a more detailed treatment of coolant system thermal hydraulics and core behaviour. Both treatments show that the core is readily quenched, without damage, by the nominal SI which assumes operation of only one pump. Margins against additional scenario and model uncertainties are assessed by assuming a delay of 900 s (the time needed to actuate the remaining pumps) and a variety of assumptions regarding models and the number of pumps available in conjunction with both MELCOR and versions of SCDAP. Overall, the study provides confidence in the inherent robustness of the plant design with respect to LOCA during
International Nuclear Information System (INIS)
Mora Araya, Luis Diego
2013-01-01
The activity of uniform distributions of 99m Tc was quantified by the conjugate view method. The necessary factors of calibration and transmission were calculated to realize the quantification. The dependence of the estimated number of accounts within the source region and variability of the value of the transmission factor were determined, according to the size established for the region of interest, keeping constant its geometry. The images of all acquisitions were corrected by environmental background radiation and radiation dispersed, by the dual energy window method (DEW). The impact of corrections in the image were checked, both qualitatively and quantitative. The acquisition to obtain the calibration factor was realized with the same configuration and the same conditions that were used to realize the acquisition for quantification; in which, the same volume and the same geometry were used to contain the distribution of the activity of 99m Tc. The volume and geometry of the same medium attenuator have obtained a calibration factor exactly in the same circumstances in which have quantified. The behavior of the estimation of the calibration factor of the gamma camera was analyzed, according to the decay corrections of the activity and the attenuation that are applied. The dependence of the calibration factors and transmission were analyzed, according to the region of interest used in the corresponding images to estimate their values. The behavior of the estimation of the activity was determined, according to all possible combinations of the factors studied that have intervened in the quantification algorithm of conjugate view, namely, the size of the region of interest corresponding to the source region, the transmission factor , the calibration factor and background correction by simple subtraction. The results obtained of the estimates of the activity were compared. A tendency is established, indicating which have been combinations of the studied factors that
Design of special planar linkages
Zhao, Jing-Shan; Ma, Ning; Chu, Fulei
2013-01-01
Planar linkages play a very important role in mechanical engineering. As the simplest closed chain mechanisms, planar four-bar linkages are widely used in mechanical engineering, civil engineering and aerospace engineering.Design of Special Planar Linkages proposes a uniform design theory for planar four-bar linkages. The merit of the method proposed in this book is that it allows engineers to directly obtain accurate results when there are such solutions for the specified n precise positions; otherwise, the best approximate solutions will be found. This book discusses the kinematics and reach
Energy Technology Data Exchange (ETDEWEB)
Alcalde, M. Aparicio; Svaiter, N.F. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Hidalgo, G. Flores [Instituto de Fisica Teorica, Sao Paulo, SP (Brazil)
2005-12-15
We study the {lambda}/4{exclamation_point} {psi}{sup 4} massless scalar field theory in a four-dimensional Euclidean space, where all but one of the coordinates are unbounded. We are considering Dirichlet boundary conditions in two hyper planes, breaking the translation invariance of the system. We show how to implement the perturbative renormalization up to two-loop level of the theory. First, analyzing the full two and four-point functions at the one-loop level, we shown that the bulk counterterms are sufficient to render the theory finite. Meanwhile, at the two-loop level, we have to introduce also surface counterterms in the bare Lagrangian in order to make finite the full two and also four-point Schwinger functions. (author)
Electroweak corrections to H->ZZ/WW->4 leptons
International Nuclear Information System (INIS)
Bredenstein, A.; Denner, A.; Dittmaier, S.; Weber, M.M.
2006-01-01
We provide predictions for the decays H->ZZ->4-bar and H->WW->4-bar including the complete electroweak O(α) corrections and improvements by higher-order final-state radiation and two-loop corrections proportional to G μ 2 M H 4 . The gauge-boson resonances are described in the complex-mass scheme. We find corrections at the level of 1-8% for the partial widths
Energy Technology Data Exchange (ETDEWEB)
Mineev, Mark [Los Alamos National Laboratory
2008-01-01
The planar elliptic extension of the Laplacian growth is, after a proper parametrization, given in a form of a solution to the equation for areapreserving diffeomorphisms. The infinite set of conservation laws associated with such elliptic growth is interpreted in terms of potential theory, and the relations between two major forms of the elliptic growth are analyzed. The constants of integration for closed form solutions are identified as the singularities of the Schwarz function, which are located both inside and outside the moving contour. Well-posedness of the recovery of the elliptic operator governing the process from the continuum of interfaces parametrized by time is addressed and two examples of exact solutions of elliptic growth are presented.
Improved Dynamic Planar Point Location
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Arge, Lars; Georgiadis, Loukas
2006-01-01
We develop the first linear-space data structures for dynamic planar point location in general subdivisions that achieve logarithmic query time and poly-logarithmic update time.......We develop the first linear-space data structures for dynamic planar point location in general subdivisions that achieve logarithmic query time and poly-logarithmic update time....
Planar channeling observed by radiography
International Nuclear Information System (INIS)
Delsarte, Guy
1970-06-01
Radiographies of crystals by means of channeled particles exhibit channeling patterns. The origin of these patterns is studied, The role played by planar channeling is demonstrated. It is shown that these patterns are local amplifications of the process generating the images of a crystal on the radiography. It is deduced that planar channeling plays a determining role in the formation of these images. An orientation chamber using transmitted planar channels is described. The orientation of very small grains in a polycrystal can be very easily obtained, (author) [fr
Directory of Open Access Journals (Sweden)
Mehdi Dehjourian
2016-08-01
Full Text Available The containment response during the first 24 hours of a low-pressure severe accident scenario in a nuclear power plant with a two-loop Westinghouse-type pressurized water reactor was simulated with the CONTAIN 2.0 computer code. The accident considered in this study is a large-break loss-of-coolant accident, which is not successfully mitigated by the action of safety systems. The analysis includes pressure and temperature responses, as well as investigation into the influence of spray on the retention of fission products and the prevention of hydrogen combustion in the containment.
Planar algebra of the subgroup-subfactor
Indian Academy of Sciences (India)
G in terms of operator matrices. We also obtain an identification between the planar algebra of the fixed algebra sub- factor RG ⊂ RH and the G-invariant planar subalgebra of the planar algebra of the 'flip' of ⋆n. Keywords. Planar algebras; subfactors; standard invariant. 1. Introduction. For every pair H ⊂ G of finite groups, ...
Quasi-planar elemental clusters in pair interactions approximation
Directory of Open Access Journals (Sweden)
Chkhartishvili Levan
2016-01-01
Full Text Available The pair-interactions approximation, when applied to describe elemental clusters, only takes into account bonding between neighboring atoms. According to this approach, isomers of wrapped forms of 2D clusters – nanotubular and fullerene-like structures – and truly 3D clusters, are generally expected to be more stable than their quasi-planar counterparts. This is because quasi-planar clusters contain more peripheral atoms with dangling bonds and, correspondingly, fewer atoms with saturated bonds. However, the differences in coordination numbers between central and peripheral atoms lead to the polarization of bonds. The related corrections to the molar binding energy can make small, quasi-planar clusters more stable than their 2D wrapped allotropes and 3D isomers. The present work provides a general theoretical frame for studying the relative stability of small elemental clusters within the pair interactions approximation.
Electroweak corrections to hadronic photon production at large transverse momenta
International Nuclear Information System (INIS)
Kuehn, Johann H.; Kulesza, Anna; Pozzorini, Stefano; Schulze, Markus
2006-01-01
We study the impact of electroweak radiative corrections on direct production of photons with high transverse momenta at hadron colliders. Analytic results for the weak one-loop corrections to the parton scattering reaction q-bar q→γg and its crossed variants are presented. For the high-energy region, where the corrections are strongly enhanced by logarithms of s-circumflex /M W 2 , we derive simple asymptotic expressions which approximate the exact one-loop results with high precision. The dominant two-loop electroweak contributions are also calculated. Numerical results are presented for the LHC and the Tevatron. The corrections are negative and their size increases with transverse momentum. For the LHC, where transverse momenta of 2 TeV or more can be reached, the size of the one- and two-loop effects amounts up to -17% and +3%, respectively. At the Tevatron, with transverse momenta up to 400 GeV, the one-loop corrections do not exceed -4% and the two-loop effects are negligible. Finally we compare the cross sections for hadronic production of photons and Z bosons and find that the electroweak corrections have an important impact on their ratio
International Nuclear Information System (INIS)
Tumeh, S.S.; Rosenthal, D.; Kaplan, W.D.; English, R.E.; Holman, B.L.
1985-01-01
To determine the value of Ga-67 single photon emission computed tomography (SPECT) in patients (pts) with malignant chest disease, the authors compared Ga-67 planar scans (ps) and SPECT with the medical records in twenty-five consecutive patients. Twenty-three examinations were performed on 17 pts with Hodgkin's disease (HD) and three pts with non-Hodgkin's lymphoma. Five examinations were performed on 5 pts with bronchogenic carcinoma (BC). The two modalities were evaluated for (1) presence or absence of disease, (2) number of foci of abnormal uptake and (3) extent of disease. In pts with lymphoma, SPECT defined the extent of disease better than planar imaging in eight examinations; it demonstrated para-cardial involvement in one pt, separated hilar from mediastinal disease in 4, and demonstrated posterior mediastinal disease in 3. SPECT clarified suspicious foci on planar images in seven examinations, correctly ruled out disease in two pts with equivocal planar images and did not exchange planar image findings in six examinations. In pts with bronchogenic carcinoma, both medalities correctly ruled out mediastinal involvement in three pts. SPECT detected mediastinal lymph node involvement in one pt with equivocal planar images. Both SPECT and planar imaging missed direct tumor extension to the mediastinum in one pt. They conclude that Ga-67 with SPECT is better than planar images for staging of chest lymphoma and BC. Since it defines different lymph node groups it carries a good potential for staging as well as follow up of those pts
Directory of Open Access Journals (Sweden)
Angeliki Birmpa
2015-08-01
Full Text Available In the present study, the effectiveness of two loop-mediated isothermal amplification (LAMP assays was evaluated. Samples of romaine lettuce, strawberries, cherry tomatoes, green onions and sour berries were inoculated with known dilutions (100-108 CFU/g of produce of S. Enteritidis and L. monocytogenes. With LAMP assay, pathogens can be detected in less than 60 min. The limits of detection of S. Enteritidis and L. monocytogenes depended on the food sample tested and on the presence of enrichment step. After enrichment steps, all food samples were found positive even at low initial pathogen levels. The developed LAMP, assays, are expected to become a valuable, robust, innovative, powerful, cheap and fast monitoring tool, which can be extensively used for routine analysis, and screening of contaminated foods by the food industry and the Public Food Health Authorities.
Political Correctness--Correct?
Boase, Paul H.
1993-01-01
Examines the phenomenon of political correctness, its roots and objectives, and its successes and failures in coping with the conflicts and clashes of multicultural campuses. Argues that speech codes indicate failure in academia's primary mission to civilize and educate through talk, discussion, thought,166 and persuasion. (SR)
Approximation by planar elastic curves
DEFF Research Database (Denmark)
Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge
2016-01-01
We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient-driven...
The planar cubic Cayley graphs
Georgakopoulos, Agelos
2018-01-01
The author obtains a complete description of the planar cubic Cayley graphs, providing an explicit presentation and embedding for each of them. This turns out to be a rich class, comprising several infinite families. He obtains counterexamples to conjectures of Mohar, Bonnington and Watkins. The author's analysis makes the involved graphs accessible to computation, corroborating a conjecture of Droms.
Contracting a planar graph efficiently
DEFF Research Database (Denmark)
Holm, Jacob; Italiano, Giuseppe F.; Karczmarz, Adam
2017-01-01
We present a data structure that can maintain a simple planar graph under edge contractions in linear total time. The data structure supports adjacency queries and provides access to neighbor lists in O(1) time. Moreover, it can report all the arising self-loops and parallel edges. By applying th...
The planar cubic cayley graphs
Georgakopoulos, Agelos
2018-01-01
The author obtains a complete description of the planar cubic Cayley graphs, providing an explicit presentation and embedding for each of them. This turns out to be a rich class, comprising several infinite families. He obtains counterexamples to conjectures of Mohar, Bonnington and Watkins. The author's analysis makes the involved graphs accessible to computation, corroborating a conjecture of Droms.
Poling of Planar Silica Waveguides
DEFF Research Database (Denmark)
Arentoft, Jesper; Kristensen, Martin; Jensen, Jesper Bo
1999-01-01
UV-written planar silica waveguides are poled using two different poling techniques, thermal poling and UV-poling. Thermal poling induces an electro-optic coefficient of 0.067 pm/V. We also demonstrate simultaneous UV-writing and UV-poling. The induced electro-optic effect shows a linear dependence...
The planar dynamics of airships
Regan, F. J.
1975-01-01
The forces and moments acting upon a LTA vehicle are considered in order to develop parameters describing planar motion. Similar expressions for HTA vehicles will be given to emphasize the greater complexity of aerodynamic effects when buoyancy effects cannot be neglected. A brief summary is also given of the use of virtual mass coefficients to calculate loads on airships.
Electroweak Corrections to W-pair Production at LHC and ILC
Metzler, Falk; Steinhauser, M.
We consider electro-weak beam corrections for W-pair production in electron-positron, as well as Quark-Antiquark annihilation at high energies. In this energy range the radiation corrections are dominated by Sudakov logarithms. With the help of evolutionary equations, these logarithms can be summed up. We present two-loop corrections up to next-next logarithms for the production of transversal and longitudinally polarized W-boson pairs.
Planarization of metal films for multilevel interconnects
Tuckerman, D.B.
1985-06-24
In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping lase pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.
Manufacturing of planar ceramic interconnects
Energy Technology Data Exchange (ETDEWEB)
Armstrong, B.L.; Coffey, G.W.; Meinhardt, K.D.; Armstrong, T.R. [Pacific Northwest National Lab., Richland, WA (United States)
1996-12-31
The fabrication of ceramic interconnects for solid oxide fuel cells (SOFC) and separator plates for electrochemical separation devices has been a perennial challenge facing developers. Electrochemical vapor deposition (EVD), plasma spraying, pressing, tape casting and tape calendering are processes that are typically utilized to fabricate separator plates or interconnects for the various SOFC designs and electrochemical separation devices. For sake of brevity and the selection of a planar fuel cell or gas separation device design, pressing will be the only fabrication technique discussed here. This paper reports on the effect of the characteristics of two doped lanthanum manganite powders used in the initial studies as a planar porous separator for a fuel cell cathode and as a dense interconnect for an oxygen generator.
Enjoyment of Euclidean planar triangles
Srinivasan, V. K.
2013-09-01
This article adopts the following classification for a Euclidean planar ?, purely based on angles alone. A Euclidean planar triangle is said to be acute angled if all the three angles of the Euclidean planar ? are acute angles. It is said to be right angled at a specific vertex, say B, if the angle ? is a right angle with the two remaining angles as acute angles. It is said to be obtuse angled at the vertex B if ? is an obtuse angle, with the two remaining angles as acute angles. In spite of the availability of numerous text books that contain our human knowledge of Euclidean plane geometry, softwares can offer newer insights about the characterizations of planar geometrical objects. The author's characterizations of triangles involve points like the centroid G, the orthocentre H of the ?, the circumcentre S of the ?, the centre N of the nine-point circle of the ?. Also the radical centre rc of three involved diameter circles of the sides BC, AC and AB of the ? provides a reformulation of the orthocentre, resulting in an interesting theorem, dubbed by the author as 'Three Circles Theorem'. This provides a special result for a right-angled ?, again dubbed by the author as 'The Four Circles Theorem'. Apart from providing various inter connections between the geometrical points, the relationships between shapes of the triangle and the behaviour of the points are reasonably explored in this article. Most of these results will be useful to students that take courses in Euclidean Geometry at the college level and the high school level. This article will be useful to teachers in mathematics at the high school level and the college level.
Superconducting Planar Devices for Cosmology
Ghribi, A.; Bélier, B.; Boussaha, F.; Bréelle, E.; Piat, M.; Spinelli, S.; Tartari, A.; Zannoni, M.
2009-12-01
To enhance systematics cleaness of a new advanced detection architecture for B-modes detection of the Cosmic Microwave Background polarization and in the framework of the ground based instrument QUBIC (Q and U Bolometric Interferometer for Cosmology), we study planar superconducting devices. Waveguide to microstrip transition, orthomode transducer and phase switches are therefore investigated as well as their cryogenic characterization at millimeter waves. We also show design and nanotechnology fabrication process of these devices.
Planar stochastic hyperbolic infinite triangulations
Curien, Nicolas
2014-01-01
Pursuing the approach of Angel & Ray, we introduce and study a family of random infinite triangulations of the full-plane that satisfy a natural spatial Markov property. These new random lattices naturally generalize Angel & Schramm's Uniform Infinite Planar Triangulation (UIPT) and are hyperbolic in flavor. We prove that they exhibit a sharp exponential volume growth, are non-Liouville, and that the simple random walk on them has positive speed almost surely. We conjecture that these infinit...
[Optical Design of Miniature Infrared Gratings Spectrometer Based on Planar Waveguide].
Li, Yang-yu; Fang, Yong-hua; Li, Da-cheng; Liu, Yang
2015-03-01
In order to miniaturize an infrared spectrometer, we analyze the current optical design of miniature spectrometers and propose a method for designing a miniature infrared gratings spectrometer based on planar waveguide. Common miniature spectrometer uses miniature optical elements to reduce the size of system, which also shrinks the effective aperture. So the performance of spectrometer has dropped. Miniaturization principle of planar waveguide spectrometer is different from the principle of common miniature spectrometer. In planar waveguide spectrometer, the propagation of light is limited in a thin planar waveguide, which looks like the whole optical system is squashed flat. In the direction parallel to the planar waveguide, the light through the slit is collimated, dispersed and focused. And a spectral image is formed in the detector plane. This propagation of light is similar to the light in common miniature spectrometer. In the direction perpendicular to the planar waveguide, light is multiple reflected by the upper and lower surfaces of the planar waveguide and propagates in the waveguide. So the size of corresponding optical element could be very small in the vertical direction, which can reduce the size of the optical system. And the performance of the spectrometer is still good. The design method of the planar waveguide spectrometer can be separated into two parts, Czerny-Turner structure design and planar waveguide structure design. First, by using aberration theory an aberration-corrected (spherical aberration, coma, focal curve) Czerny-Turner structure is obtained. The operation wavelength range and spectral resolution are also fixed. Then, by using geometrical optics theory a planar waveguide structure is designed for reducing the system size and correcting the astigmatism. The planar waveguide structure includes a planar waveguide and two cylindrical lenses. Finally, they are modeled together in optical design software and are optimized as a whole. An
Electromagnetic corrections to baryon masses
International Nuclear Information System (INIS)
Durand, Loyal; Ha, Phuoc
2005-01-01
We analyze the electromagnetic contributions to the octet and decuplet baryon masses using the heavy-baryon approximation in chiral effective field theory and methods we developed in earlier analyses of the baryon masses and magnetic moments. Our methods connect simply to Morpurgo's general parametrization of the electromagnetic contributions and to semirelativistic quark models. Our calculations are carried out including the one-loop mesonic corrections to the basic electromagnetic interactions, so to two loops overall. We find that to this order in the chiral loop expansion there are no three-body contributions. The Coleman-Glashow relation and other sum rules derived in quark models with only two-body terms therefore continue to hold, and violations involve at least three-loop processes and can be expected to be quite small. We present the complete formal results and some estimates of the matrix elements here. Numerical calculations will be presented separately
Mass spectrum bound state systems with relativistic corrections
Energy Technology Data Exchange (ETDEWEB)
Dineykhan, M; Zhaugasheva, S A [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Toinbaeva, N Sh; Jakhanshir, A [al-Farabi Kazak National University, 480012 Almaty (Kazakhstan)
2009-07-28
Based on the investigation of the asymptotic behaviour of the polarization loop function for charged n scalar particles in an external gauge field, we determine the interaction Hamiltonian including relativistic corrections. The mass spectrum of the bound state is analytically derived. The mechanism for arising of the constituent mass of the relativistic bound-state forming particles is explained. The mass and the constituent mass of the two-, three- and n-body relativistic bound states are calculated taking into account relativistic corrections. The corrections arising due to the one- and two-loop electron polarization to the energy spectrum of muonic hydrogen with orbital and radial excitations are calculated.
An asymptotic formula for marginal running coupling constants and universality of loglog corrections
Mukaida, Hisamitsu
2004-01-01
Given a two-loop beta function for multiple marginal coupling constants, we derive an asymptotic formula for the running coupling constants driven to an infrared fixed point. It can play an important role in universal loglog corrections to physical quantities.
Planar optical correlators integrated with binary optical lens.
Xu, Ping; Hong, Chunquan; Cheng, Guanxiao; Zhou, Liang; Sun, Zhilong
2015-03-09
Planar optical correlators (POCs) can achieve smaller volume of optical system and hence have important applications to identify dynamic targets in complex scenarios. POCs, however, generally have serious astigmatism and optical efficiency loss introduced by its refractive lens with a zigzag optical beam. To conquer the disadvantages of POCs, we propose a type of binary optical planar-integrated optical correlator. The correlator incorporates two pieces of reflective binary optical lens as Fourier transform lens and one spatial light modulator as a programmable filter. The off-axis aberrations commonly occurred in POCs can be corrected by using reflective binary optical lens instead of refractive lens. As a model of hybrid numerical-optical correlator using optoelectronic interface, the proposal is helpful to improve the integration and flexibility and robustness of POCs.
Planar channeling in superlattices: Theory
International Nuclear Information System (INIS)
Ellison, J.A.; Picraux, S.T.; Allen, W.R.; Chu, W.K.
1988-01-01
The well-known continuum model theory for planar channeled energetic particles in perfect crystals is extended to layered crystalline structures and applied to superlattices. In a strained-layer structure, the planar channels with normals which are not perpendicular to the growth direction change their direction at each interface, and this dramatically influences the channeling behavior. The governing equation of motion for a planar channeled ion in a strained-layer superlattice with equal layer thicknesses is a one degree of freedom nonlinear oscillator which is periodically forced with a sequence of δ functions. These δ functions, which are of equal spacing and amplitude with alternating sign, represent the tilts at each of the interfaces. Thus upon matching an effective channeled particle wavelength, corresponding to a natural period of the nonlinear oscillator, to the period of the strained-layer superlattice, corresponding to the periodic forcing, strong resonance effects are expected. The condition of one effective wavelength per period corresponds to a rapid dechanneling at a well-defined depth (catastrophic dechanneling), whereas two wavelengths per period corresponds to no enhanced dechanneling after the first one or two layers (resonance channeling). A phase plane analysis is used to characterize the channeled particle motion. Detailed calculations using the Moliere continuum potential are compared with our previously described modified harmonic model, and new results are presented for the phase plane evolution, as well as the dechanneling as a function of depth, incident angle, energy, and layer thickness. General scaling laws are developed and nearly universal curves are obtained for the dechanneling versus depth under catastrophic dechanneling
New planar trace humidity sensor
Tiebe, Carlo; Hübert, Thomas; Lorek, Andreas; Wernecke, Roland
2012-01-01
A new planar sensor element for continuous coulometric trace humidity measurements in industrial gases has been developed. In order to ensure precise measurements a calibration facility including a precision dew point hygrometer as a reference device was developed. The sensor can measure the humidity in the frost point temperature range of -20 °C to -80 °C and has an expanded uncertainty of 2 K, a fast reaction time and a settling time of the entire system from 15 to 30 min.
Modeling the planar configuration of extraordinary magnetoresistance
International Nuclear Information System (INIS)
El-Ahmar, S; Pozniak, A A
2015-01-01
Recently the planar version of the extraordinary magnetoresistance (EMR) magnetic field sensor has been constructed and verified in practice. Planar configuration of the EMR device gives many technological advantages, it is simpler than the classic and allows one to build the sensor using electric materials of the new type (such as graphene or topological insulators) much easier. In this work the planar configuration of the EMR sensor is investigated by performing computational simulations using the finite element method (FEM). The computational comparison of the planar and classic configurations of EMR is presented using three-dimensional models. Various variants of the geometry of EMR sensor components are pondered and compared in the planar and classic version. Size of the metal overlap is considered for sensor optimization as well as various semiconductor-metal contact resistance dependences of the EMR signal. Based on computational simulations, a method for optimal placement of electric terminals in a planar EMR device is proposed. (paper)
Advances in Planar and Integrated Magnetics
DEFF Research Database (Denmark)
Ouyang, Ziwei
‐fashioned wire wound types, and thus planar magnetics, has in recent years, become increasingly popular in high frequency power converters. First, an overview of basic planar magnetics technology used in general dc‐dc converters is presented. PCB or flexible PCB windings as a main construction together...... with planar cores yield a number of advantages over the conventional magnetics. Meanwhile, some limitations of planar magnetics are also introduced. Secondly, fundamental characteristics of planar magnetics are investigated through winding conduction loss, core loss, leakage inductance and interwinding......The trend toward high power density, high operating frequency, and low profile in power converters has exposed a number of limitations in the use of conventional wirewound magnetic component structures. Transformers made of the planar principle eliminate virtually some shortcomings of old...
Planar Hall effect bridge magnetic field sensors
DEFF Research Database (Denmark)
Henriksen, A.D.; Dalslet, Bjarke Thomas; Skieller, D.H.
2010-01-01
Until now, the planar Hall effect has been studied in samples with cross-shaped Hall geometry. We demonstrate theoretically and experimentally that the planar Hall effect can be observed for an exchange-biased ferromagnetic material in a Wheatstone bridge topology and that the sensor signal can...... be significantly enhanced by a geometric factor. For the samples in the present study, we demonstrate an enhancement of the sensor output by a factor of about 100 compared to cross-shaped sensors. The presented construction opens a new design and application area of the planar Hall effect, which we term planar...
Improved optical planar waveguides for lasers
National Aeronautics and Space Administration — Planar Waveguides (PWGs) are extremely versatile and have demonstrated excellent performance but are difficult to manufacture. We will demonstrate a new, simpler,...
Planar waveguide sensor of ammonia
Rogoziński, Roman; Tyszkiewicz, Cuma; Karasiński, Paweł; Izydorczyk, Weronika
2015-12-01
The paper presents the concept of forming ammonia sensor based on a planar waveguide structure. It is an amplitude sensor produced on the basis of the multimode waveguide. The technological base for this kind of structure is the ion exchange method and the sol-gel method. The planar multimode waveguide of channel type is produced in glass substrate (soda-lime glass of Menzel-Glaser company) by the selective Ag+↔Na+ ion exchange. On the surface of the glass substrate a porous (~40%) silica layer is produced by the sol-gel method. This layer is sensitized to the presence of ammonia in the surrounding atmosphere by impregnation with Bromocresol Purple (BCP) dye. Therefore it constitutes a sensor layer. Spectrophotometric tests carried out showed about 50% reduction of cross-transmission changes of such sensor layer for a wave λ=593 nm caused by the presence of 25% ammonia water vapor in its ambience. The radiation source used in this type of sensor structure is a light emitting diode LED. The gradient channel waveguide is designed for frontal connection (optical glue) with a standard multimode telecommunications waveguide 62.5/125μm.
Virtual O(αs) corrections to the inclusive decay b→sγ
International Nuclear Information System (INIS)
Greub, C.; Hurth, T.; Wyler, D.
1996-01-01
We present in detail the calculation of the O(α s ) virtual corrections to the matrix element for b→sγ. In addition to the one-loop virtual corrections of the electromagnetic and color dipole operators O 7 and O 8 , we include the important two-loop contribution of the four-Fermi operator O 2 . By applying the Mellin-Barnes representation to certain internal propagators, the result of the two-loop diagrams is obtained analytically as an expansion in m c /m b . These results are then combined with existing O(α s ) bremsstrahlung corrections in order to obtain the inclusive rate for B→X s γ. The new contributions drastically reduce the large renormalization scale dependence of the leading logarithmic result. Thus, a very precise standard model prediction for this inclusive process will become possible once the corrections to the Wilson coefficients are also available. copyright 1996 The American Physical Society
Energy Technology Data Exchange (ETDEWEB)
Beiser, L. [Beiser (Leo) Inc., Flushing, NY (United States); Veligdan, J. [Brookhaven National Lab., Upton, NY (United States)
1996-04-01
A Planar Optic Display (POD) is being built and tested for suitability as a high brightness replacement for the cathode ray tube, (CRT). The POD display technology utilizes a laminated optical waveguide structure which allows a projection type of display to be constructed in a thin (I to 2 inch) housing. Inherent in the optical waveguide is a black cladding matrix which gives the display a black appearance leading to very high contrast. A Digital Micromirror Device, (DMD) from Texas Instruments is used to create video images in conjunction with a 100 milliwatt green solid state laser. An anamorphic optical system is used to inject light into the POD to form a stigmatic image. In addition to the design of the POD screen, we discuss: image formation, image projection, and optical design constraints.
Beiser, Leo; Veligdan, James T.
1996-05-01
A planar optic display (POD) is being built and tested for suitability as a high brightness replacement for the cathode ray tube, (CRT). The POD display technology utilizes a laminated optical waveguide structure which allows a projection type of display to be constructed in a thin (1 to 2 inch) housing. Inherent in the optical waveguide is a black cladding matrix which gives the display a black appearance leading to very high contrast. A digital micromirror device, (DMD) from Texas Instruments is used to create video images in conjunction with a 100 milliwatt green solid state laser. An anamorphic optical system is used to inject light into the POD to form a stigmatic image. In addition to the design of the POD screen, we discuss: image formation, image projection, and optical design constraints.
Planar algebra of the subgroup-subfactor
Indian Academy of Sciences (India)
The crucial step in this identification is an exhibition of a model for the basic construction tower, and thereafter of the standard invariant of R ⋊ H ⊂ R ⋊ G in terms of operator matrices. We also obtain an identification between the planar algebra of the fixed algebra subfactor R G ⊂ R H and the -invariant planar subalgebra ...
Positron Emission Mammotomography with Dual Planar Detectors
Energy Technology Data Exchange (ETDEWEB)
Mark Smith; Raymond Raylman; Stanislaw Majewski
2003-06-29
Positron emission mammography (PEM) is usually performed with two stationary planar detectors above and below a compressed breast. There is image blurring normal to the detectors due to the limited angular range of the lines of response. Positron emission mammotomography (PEM-T) with dual planar detectors rotating about the breast can obtain complete angular sampling and has the potential to improve activity estimation.
Planar algebra of the subgroup-subfactor
Indian Academy of Sciences (India)
of planar algebra of a bipartite graph as given by Jones [5], and discuss how it and its dual behave under the action ..... Repeated applications of the compatibility condition for tangle maps with respect to composition of ... The importance of planar algebras in subfactor theory lies in the following theorem of. Jones: Theorem ...
The Planar Sandwich and Other 1D Planar Heat Flow Test Problems in ExactPack
Energy Technology Data Exchange (ETDEWEB)
Singleton, Jr., Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-01-24
This report documents the implementation of several related 1D heat flow problems in the verification package ExactPack [1]. In particular, the planar sandwich class defined in Ref. [2], as well as the classes PlanarSandwichHot, PlanarSandwichHalf, and other generalizations of the planar sandwich problem, are defined and documented here. A rather general treatment of 1D heat flow is presented, whose main results have been implemented in the class Rod1D. All planar sandwich classes are derived from the parent class Rod1D.
Radiative corrections due to a heavy Higgs-particle
International Nuclear Information System (INIS)
Van der Bij, J.J.
1984-01-01
The leading two-loop corrections to the rho parameter and to the vectorboson masses was calculated in the limit of large Higgs-mass. The corrections appear to be too small to be measured, of the order of a few tenths of a percent. For rho perturbation theory breaks down for a Higgs-mass of 11 TeV and larger, for the vectorboson mass this happens for a Higgs-mass of a 4 TeV or larger. There is no direct correspondence between these results and the poles at n=3 in the gauged non-linear σ-model
Higher-order soft corrections to squark hadro-production
Energy Technology Data Exchange (ETDEWEB)
Langenfeld, U.; Moch, S.
2009-01-15
We present new predictions for the total cross section of squark pair-production at Tevatron and LHC through next-to-next-to-leading order within the Minimal Supersymmetric Standard Model. The results are based on the numerically dominant soft corrections. They are exact in all logarithmically enhanced terms near threshold, include the Coulomb corrections at two loops and exact scale dependence. We translate the increased total cross section at next-to-next-to-leading order into improved exclusion limits for squark masses and we investigate the scale dependence as well as the sensitivity on the parton luminosity. (orig.)
Double-Higgs boson production in the high-energy limit: planar master integrals
Davies, Joshua; Mishima, Go; Steinhauser, Matthias; Wellmann, David
2018-03-01
We consider the virtual corrections to the process gg → HH at NLO in the high energy limit and compute the corresponding planar master integrals in an expansion for small top quark mass. We provide details on the evaluation of the boundary conditions and present analytic results expressed in terms of harmonic polylogarithms.
International Nuclear Information System (INIS)
Rossleigh, M.A.; Christian, C.L.; Craig, J.C.; Howman-Giles, R.B.; Grunewald, S.
2004-01-01
Purpose: To determine whether the provision of DMSA images obtained by pinhole collimation reduces inter-observer variability of reporting compared with planar DMSA images alone. Methods: One hundred consecutive DMSA images were independently interpreted three times (pinhole alone, planar alone, pinhole and planar) by four participating nuclear medicine specialists from different departments and in random order. The presence or absence of renal parenchymal abnormality was classified using the modified four level grading system of Goldraich with mean values for the 6 comparisons reported. Results: The proportion of DMSA images interpreted as abnormal was 31% for planar, 34% for pinhole and 33% for planar with pinhole. Agreement was 89% for planar alone, 89% for pinhole alone and 90% for planar with pinhole, with kappa values 0.74, 0.75 and 0.80 respectively for the normal-abnormal scan classification of individual children. These results did not vary appreciably whether interpretation of patients, kidneys or kidney zones was compared. Reasons for disagreement in reporting included different interpretations of 'abnormalities' as normal anatomical variations (splenic impression, fetal lobulation, duplex collecting systems, column of Bertin) or true parenchymal abnormalities, different adjustments in thresholds for reporting abnormality when images were technically suboptimal, different weighting given to pinhole and planar images when both were provided, and error. Conclusion: Four experienced nuclear medicine physicians showed substantial agreement in the interpretation of planar alone, pinhole alone and planar with pinhole DMSA images, but the provision of both sets of images, planar and pinhole, did not reduce variability. (authors)
Correction of polarization error in scanned array weather radar antennas
Pang, C.; Hoogeboom, P.; Russchenberg, H.; Wang, T.; Dong, J.; Wang, X.
2014-01-01
In this paper, the polarization error correction of dual-polarized planar scanned array weather radar in alternately transmitting and simultaneously receiving (ATSR) mode is analyzed. A method based on point correction and a method taking the complete array patterns into account are discussed. To
Planar impact experiments for EOS measurements
International Nuclear Information System (INIS)
Furnish, M.D.
1993-01-01
The community concerned with the numerical modeling of groundshock produced by underground nuclear tests must have access to materials data to benchmark models of rock behavior. Historically the primary source of these data has been planar impact experiments. These experiments have involved gun, explosive and electrical launchers. Other methods of introducing planar shocks include shock driving by in-contact explosives or laser bursts. This paper briefly describes gun launcher-based planar impact methods used to characterize geological materials at Sandia National Laboratories
DEFF Research Database (Denmark)
Grundle, D S; Löscher, C R; Krahmann, G
2018-01-01
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.......A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper....
Compressibility effects in planar wakes
Hickey, Jean-Pierre; Hussain, Fazle; Wu, Xiaohua
2010-11-01
Far-field, temporally evolving planar wakes are studied by DNS to evaluate the effect of compressibility on the flow. A high-order predictor-corrector code was developed and fully validated against canonical compressible test cases. In this study, wake simulations are performed at constant Reynolds number for three different Mach numbers: Ma= 0.2, 0.8 and 1.2. The domain is doubly periodic with a non-reflecting boundary in the cross-flow and is initialized by a randomly perturbed laminar profile. The compressibility of the flow modifies the observed structures which show greater three-dimensionality. A self-similar period develops in which the square of the wake half-width increase linearly with time and the Reynolds stress statistics at various times collapse using proper scaling parameters. The growth-rate increases with increasing compressibility of the flow: an observation which is substantiated by experimental results but is in stark contrast with the high-speed mixing-layer. As the growth-rate is related to the mixing ability of the flow, the impact of compressibility is of fundamental importance. Therefore, we seek an explanation of the modified growth-rate by investigating the turbulent kinetic energy equation. From the analysis, it can be conjectured that the pressure-strain term might play a role in the modified growth-rate.
DEFF Research Database (Denmark)
Ouyang, Ziwei; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.
2009-01-01
to reduce leakage inductance further. Some important issues are presented to acquire desired leakage inductance. The design and modeling of 1 kW planar transformer is presented. In order to verify the analytical method for leakage inductance in this paper, finite element analysis (FEA) and measurement...... (MMF) and energy distribution in planar transformer and correct the formula of leakage inductance proposed by previous publications. The investigation of different winding arrangements shows significant advantages of interleaving structure. In this work, a novel half turn structure is proposed...
Modified planar functions and their components
DEFF Research Database (Denmark)
Anbar Meidl, Nurdagül; Meidl, Wilfried Meidl
2017-01-01
functions in odd characteristic as a vectorial bent function. We finally point out that though these components behave somewhat different than the multivariate bent4 functions, they are bent or semibent functions shifted by a certain quadratic term, a property which they share with their multivariate......Zhou ([20]) introduced modified planar functions in order to describe (2n; 2n; 2n; 1) relative difference sets R as a graph of a function on the finite field F2n, and pointed out that projections of R are difference sets that can be described by negabent or bent4 functions, which are Boolean...... functions given in multivariate form. One of the objectives of this paper is to contribute to the understanding of these component functions of modified planar functions. Moreover, we obtain a description of modified planar functions by their components which is similar to that of the classical planar...
Alliances and Bisection Width for Planar Graphs
DEFF Research Database (Denmark)
Olsen, Martin; Revsbæk, Morten
2013-01-01
An alliance in a graph is a set of vertices (allies) such that each vertex in the alliance has at least as many allies (counting the vertex itself) as non-allies in its neighborhood of the graph. We show that any planar graph with minimum degree at least 4 can be split into two alliances...... in polynomial time. We base this on a proof of an upper bound of n on the bisection width for 4-connected planar graphs with an odd number of vertices. This improves a recently published n + 1 upper bound on the bisection width of planar graphs without separating triangles and supports the folklore conjecture...... that a general upper bound of n exists for the bisection width of planar graphs....
Generators for finite depth subfactor planar algebras
Indian Academy of Sciences (India)
The main result of Kodiyalam and Tupurani [3] shows that a subfactor planar algebra of finite depth is singly generated with a finite presentation. If P is a subfactor planar algebra of depth k, it is shown there that a single 2k-box generates P. It is natural to ask what the smallest s is such that a single s-box generates P. While ...
Planar half-cell shaped precursor body
DEFF Research Database (Denmark)
2015-01-01
The invention relates to a half-cell shaped precursor body of either anode type or cathode type, the half-cell shaped precursor body being prepared to be free sintered to form a sintered or pre-sintered half-cell being adapted to be stacked in a solid oxide fuel cell stack. The obtained half......-cell has an improved planar shape, which remains planar also after a sintering process and during temperature fluctuations....
Blacher, René
2010-01-01
Ce rapport complete les deux rapports précédents et apporte une explication plus simple aux résultats précédents : à savoir la preuve que les suites obtenues sont aléatoires.; In previous reports, we have show how to transform a text $y_n$ in a random sequence by using functions of Fibonacci $T_q$. Now, in this report, we obtain a clearer result by proving that $T_q(y_n)$ has the IID model as correct model. But, it is necessary to define correctly a correct model. Then, we study also this pro...
Comparative methods for quantifying thyroid volume using planar imaging and SPECT
International Nuclear Information System (INIS)
Zaidi, H.
1996-01-01
Thyroid volume determination using planar imaging is a procedure often performed in routine nuclear medicine, but is hampered by several physical difficulties, in particular by structures which overlie or underlie the organ of interest. SPECT enables improved accuracy over planar imaging in the determination of the volume since it is derived from the 3-D data rather than from a 2-D projection with a certain geometric assumption regarding the thyroid configuration. By using the phantoms of known volume, it was possible to estimate the accuracy of 3 different methods of determining thyroid volume from planar imaging used in clinical routine. The experimental results demonstrate that compared with conventional scintigraphy, thyroid phantom volumes were most accurately determined with SPECT when attenuation and scatter corrections are performed which allows accurate radiation dosimetry in humans without the need for assumptions on organ size or concentrations. Poster 181. (author)
International Nuclear Information System (INIS)
Minoshima, Satoshi; Uchida, Yoshitaka; Anzai, Yoshimi; Uno, Kimiichi; Arimizu, Noboru
1994-01-01
This study was conducted to determine bone scintigraphic findings in nontraumatic femoral head avascular necrosis and diagnostic value of SPECT imaging following a conventional planar imaging. Forty-three femoral heads in twenty-six cases with idiopathic femoral head necrosis (n=2), systemic lupus erythematosus (n=22), aplastic anemia (n=1), and renal transplantation (n=1) were studied. The diagnosis for femoral head necrosis was based on magnetic resonance imaging as well as other diagnostic studies in all cases. Scintigraphic findings of planar and SPECT images were classified into six categories: normal (N); cold or decrease (C); partial increase with cold or decrease (PH+C); ring-like increase with a cold center (RH+C); partial increase (PH); diffuse and/or irregular increase (DH). Avascular necrosis was confirmed in twenty-four femoral heads, in which planar and SPECT images showed scintigraphic findings of N (n=3, 2), C (n=1, 3), PH+C (n=2, 8), RH+C (n=2, 3), PH (n=9, 2), and DH (n=7, 6), respectively. Femoral heads without avascular necrosis demonstrated planar and SPECT findings of N (n=16, 12), C (n=0, 6), and DH (n=3, 1), respectively. When considering C, PH+C, and RH+C as diagnostic findings for avascular necrosis, sensitivities of planar and SPECT images were 21% and 58%, and specificities were 100% and 68%, respectively. In nineteen femoral heads with normal planar findings (N), SPECT correctly identified avascular necrosis in two femoral heads and misidentified six normal femoral heads as avascular necrosis. In nineteen femoral heads with nondiagnostic abnormalities (PH, DH), SPECT correctly identified avascular necrosis in seven femoral heads and showed no false positive. Diagnostic planar findings in five femoral heads were concordant with SPECT diagnosis. These results indicate that SPECT imaging is most valuable when planar images show nondiagnostic abnormalities based on the proposed classification of scintigraphic findings. (author)
Energy Technology Data Exchange (ETDEWEB)
Minoshima, Satoshi; Uchida, Yoshitaka; Anzai, Yoshimi; Uno, Kimiichi; Arimizu, Noboru (Chiba Univ. (Japan). School of Medicine)
1994-09-01
This study was conducted to determine bone scintigraphic findings in nontraumatic femoral head avascular necrosis and diagnostic value of SPECT imaging following a conventional planar imaging. Forty-three femoral heads in twenty-six cases with idiopathic femoral head necrosis (n=2), systemic lupus erythematosus (n=22), aplastic anemia (n=1), and renal transplantation (n=1) were studied. The diagnosis for femoral head necrosis was based on magnetic resonance imaging as well as other diagnostic studies in all cases. Scintigraphic findings of planar and SPECT images were classified into six categories: normal (N); cold or decrease (C); partial increase with cold or decrease (PH+C); ring-like increase with a cold center (RH+C); partial increase (PH); diffuse and/or irregular increase (DH). Avascular necrosis was confirmed in twenty-four femoral heads, in which planar and SPECT images showed scintigraphic findings of N (n=3, 2), C (n=1, 3), PH+C (n=2, 8), RH+C (n=2, 3), PH (n=9, 2), and DH (n=7, 6), respectively. Femoral heads without avascular necrosis demonstrated planar and SPECT findings of N (n=16, 12), C (n=0, 6), and DH (n=3, 1), respectively. When considering C, PH+C, and RH+C as diagnostic findings for avascular necrosis, sensitivities of planar and SPECT images were 21% and 58%, and specificities were 100% and 68%, respectively. In nineteen femoral heads with normal planar findings (N), SPECT correctly identified avascular necrosis in two femoral heads and misidentified six normal femoral heads as avascular necrosis. In nineteen femoral heads with nondiagnostic abnormalities (PH, DH), SPECT correctly identified avascular necrosis in seven femoral heads and showed no false positive. Diagnostic planar findings in five femoral heads were concordant with SPECT diagnosis. These results indicate that SPECT imaging is most valuable when planar images show nondiagnostic abnormalities based on the proposed classification of scintigraphic findings. (author).
DEFF Research Database (Denmark)
Flachsbart, Friederike; Dose, Janina; Gentschew, Liljana
2018-01-01
The original version of this Article contained an error in the spelling of the author Robert Häsler, which was incorrectly given as Robert Häesler. This has now been corrected in both the PDF and HTML versions of the Article....
DEFF Research Database (Denmark)
Stokholm, Jakob; Blaser, Martin J.; Thorsen, Jonathan
2018-01-01
The originally published version of this Article contained an incorrect version of Figure 3 that was introduced following peer review and inadvertently not corrected during the production process. Both versions contain the same set of abundance data, but the incorrect version has the children...
Evanescent field refractometry in planar optical fiber.
Holmes, Christopher; Jantzen, Alexander; Gray, Alan C; Gow, Paul C; Carpenter, Lewis G; Bannerman, Rex H S; Gates, James C; Smith, Peter G R
2018-02-15
This Letter demonstrates a refractometer in integrated optical fiber, a new optical platform that planarizes fiber using flame hydrolysis deposition (FHD). The unique advantage of the technology is survivability in harsh environments. The platform is mechanically robust, and can survive elevated temperatures approaching 1000°C and exposure to common solvents, including acetone, gasoline, and methanol. For the demonstrated refractometer, fabrication was achieved through wet etching an SMF-28 fiber to a diameter of 8 μm before FHD planarization. An external refractive index was monitored using fiber Bragg gratings (FBGs), written into the core of the planarized fiber. A direct comparison to alternative FBG refractometers is made, for which the developed platform is shown to have comparable sensitivity, with the added advantage of survivability in harsh environments.
Inkjet-based adaptive planarization (Conference Presentation)
Singhal, Shrawan; Grigas, Michelle M.; Khusnatdinov, Niyaz; Sreenivasan, Srinivasan V.
2017-03-01
Planarization is a critical unit step in the lithography process because it enables patterning of surfaces with versatile pattern density without compromising on the stringent planarity and depth-of-focus requirements. In addition to nanoscale pattern density variation, parasitics such as pre-existing wafer topography, can corrupt the desired process output after planarization. The topography of any surface can be classified in three broad categories, depending upon the amplitude and spatial wavelength of the same [1], [2]: (i) nominal shape, (ii) nanotopography and (iii) roughness. The nominal shape is given by the largest spatial wavelengths, typically back is one technique used for micron scale device manufacturing [3]. As the name implies, a glass dielectric is spin-coated on the substrate followed by etching in a chemistry that ensures equal etching rates for both the sacrificial glass and the underlying film or substrate material. Photoresists may also be used instead of glass. However, the global planarity that can be achieved by this technique is limited. Also, planarization over a large isolated topographical feature has been studied for the reverse-tone Jet-and-Flash Imprint Lithography process, also known as JFIL-R [4]. This relies on surface tension and capillary effects to smoothen a spin-coated Si containing film that can be etched to obtain a smooth profile. To meet the stringent requirement of planarity in submicron device technologies Chemical Mechanical Planarization (CMP) is the most widely used planarization technology [5], [6]. It uses a combination of abrasive laden chemical slurry and a mechanical pad for achieving planar profiles. The biggest concern with CMP is the dependence of material removal rate on the pattern density of material, leading to the formation of a step between the high density and low-density. The step shows up as a long-range thickness variation in the planarized film, similar in scale to pre-existing substrate topography
Fatigue Behaviors of Materials Processed by Planar Twist Extrusion
Ebrahimi, Mahmoud
2017-12-01
Since the last decade, the fabrication of ultrafine grain and nanostructure metals and alloys has attracted much attention in the field of materials engineering. The present study aimed at experimentally investigating the fatigue properties that are of great importance in dynamic structures before and after the planar twist extrusion process for both commercially pure copper and 6061 aluminum alloy. The results indicated that the yield strength, tensile strength, hardness, and fatigue endurance of copper increased by about 398, 122, 198, and 183 pct, respectively, while they improved by about 429, 212, 227, and 148 pct, respectively, in aluminum alloy as compared to the initial conditions. The stress-strain curves displayed sizable reduction of strain hardening. Furthermore, grain-size correction factors based on the empirical results were introduced to include the effect of the grain-size effect on both low and high-cycle fatigue strengths of the material.
Realizable planar gradient-index solar lenses.
Kotsidas, Panagiotis; Modi, Vijay; Gordon, Jeffrey M
2012-04-01
The design of single element planar hemispherical gradient-index solar lenses that can accommodate the constraints of realistic materials and fabrication techniques are presented, and simulated with an extended and polychromatic solar source for concentrator photovoltaics at flux concentration values exceeding 1000 suns. The planar hemispherical far-field lens is created from a near-field unit magnification spherical gradient-index design, and illustrated with an f/1.40 square solar lens that allows lossless packing within a concentrator module.
Planar dynamical systems selected classical problems
Liu, Yirong; Huang, Wentao
2014-01-01
This book presents in an elementary way the recent significant developments in the qualitative theory of planar dynamical systems. The subjects are covered as follows: the studies of center and isochronous center problems, multiple Hopf bifurcations and local and global bifurcations of the equivariant planar vector fields which concern with Hilbert's 16th problem. This book is intended for graduate students, post-doctors and researchers in the area of theories and applications of dynamical systems. For all engineers who are interested the theory of dynamical systems, it is also a reasona
Validation of uniformity correction in SPECT
International Nuclear Information System (INIS)
Ekberg, S.
2002-01-01
Aim: The reconstruction algorithm in SPECT magnifies the nonuniformities from the planar data to the reconstructed data. Thus it is of great importance that the correction for non-uniformity works correctly. Usually one uniformity matrix is collected for each energy and collimator. The clinical patient acquisition may, however, be performed with different magnification, pan, rotation direction and patient positioning. All these possibilities together are a challenge for the programmer. There are several possibilities to make program errors, in particular, if there is more than one computer software involved in the acquisition, storing, correction and reconstruction of the collected data. The aim of this work is to present a method for validating uniformity correction programs and to present results from 3 gamma camera-computer systems. Materials and Methods: Seven coins (22 mm diameter, 1.5 mm thickness), were mounted with adhesive tape directly on the surface of the collimator in a diagonal pattern about 5 cm apart. A uniformity matrix was collected from a flood source. Several SPECT acquisitions were performed on a cylindrical phantom with different combinations of zoom factors, pan, rotation directions and patient positioning parameters. The coins were mounted on the collimator throughout all the acquisitions. The appearance of distinct ring artefacts in the transaxial images was used as measure of an insufficient uniformity correction. Three different gamma camera - computer systems were tested (A,B,C). One of the systems was a mix from two different company's (C). Results: The coins made a non-uniformity of about 40-50% in the uniformity and planar data. One of the three systems (A) performed the uniformity correction correctly. The second gamma camera system (B) failed in correcting data for one acquisition combination. In the mixed system (C) several faulty uniformity corrections were detected. Conclusion: A simple test method was developed for validation of
2014-12-01
Correction note for Sanders, M., Calam, R., Durand, M., Liversidge, T. and Carmont, S. A. (2008), Does self-directed and web-based support for parents enhance the effects of viewing a reality television series based on the Triple P - Positive Parenting Programme?. Journal of Child Psychology and Psychiatry, 49: 924-932. doi: 10.1111/j.1469-7610.2008.01901.x. © 2014 Association for Child and Adolescent Mental Health.
The ACE-DTU Planar Near-Field Ground Penetrating Radar Antenna Test Facility
DEFF Research Database (Denmark)
Lenler-Eriksen, Hans-Rudolph; Meincke, Peter
2004-01-01
The ACE-DTU planar near-field ground penetrating radar (GPR) antenna test facility is used to measure the plane-wave transmitting spectrum of a GPR loop antenna close to the air-soil interface by means of a probe buried in soil. Probe correction is implemented using knowledge about the complex pe...... permittivity of the soil and the current distribution of the probe....
Instanton corrections to the effective action of N=4 SYM
Bianchi, Massimo; Morales, Jose Francisco; Wen, Congkao
2015-11-01
We compute the one-instanton effective action of N=4 super Yang-Mills theory with gauge group Sp(2 N). The result can be written in a very compact and manifestly supersymmetric form involving an integral over the superspace of an irrational function of the N=4 on-shell superfields. In the Coulomb branch, the instanton corrects both the MHV and next-to-next-MHV higher derivative terms D 4 F 2 n+2 and F 2 n+4. We confirm at the non-perturbative level the non-renormalization theorems for MHV F 2 n+2 terms that are expected to receive perturbative corrections only at n-loops. We compute also the one and two-loop corrections to the D 4 F 4 term and show that its completion under SL(2,{Z}) duality is consistent with the one-instanton results of U(2) gauge group.
Miniaturized Planar Split-Ring Resonator Antenna
DEFF Research Database (Denmark)
Kim, Oleksiy S.; Breinbjerg, Olav
2009-01-01
A miniaturized planar antenna based on a broadside-coupled split ring resonator excited by an arc-shaped dipole is presented. The excitation dipole acts as a small tuning capacitor in series with a parallel RLC circuit represented by the SRR. The antenna resonance frequency and dimensions...
Numerical Study of Planar GPR Antenna Measurements
DEFF Research Database (Denmark)
Meincke, Peter; Hansen, Thorkild
2004-01-01
The formulation of planar near-field measurements of GPR antennas determines the plane-wave spectra of the GPR antenna in terms of measurements obtained with a buried probe as the GPR antenna moves over a scan plane on the ground. A numerical study investigates how the formulation is affected by (1...
PLANAR OPTICAL WAVEGUIDES WITH PHOTONIC CRYSTAL STRUCTURE
DEFF Research Database (Denmark)
2003-01-01
Planar optical waveguide comprising a core region and a cladding region comprising a photonic crystal material, said photonic crystal material having a lattice of column elements, wherein at least a number of said column elements are elongated substantially in an axial direction for said core...
Constant Width Planar Computation Characterizes ACC0
DEFF Research Database (Denmark)
Hansen, K.A.
2004-01-01
We obtain a characterization of ACC 0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all...
Constant Width Planar Computation Characterizes ACC0
DEFF Research Database (Denmark)
Hansen, Kristoffer Arnsfelt
2006-01-01
We obtain a characterization of ACC0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all...
Development of planar detectors with active edge
International Nuclear Information System (INIS)
Povoli, M.; Bagolini, A.; Boscardin, M.; Dalla Betta, G.-F.; Giacomini, G.; Vianello, E.; Zorzi, N.
2011-01-01
We report on the first batch of planar active edge sensors fabricated at Fondazione Bruno Kessler (Trento, Italy) on the way to the development of full 3D detectors with active edges. The main design and technological aspects are reported, along with selected results from the electrical characterization of detectors and test structures.
Development of planar detectors with active edge
Energy Technology Data Exchange (ETDEWEB)
Povoli, M., E-mail: povoli@disi.unitn.it [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento, Via Sommarive, 14, I-38123 Povo di Trento (Italy); INFN, Sezione di Padova (Gruppo Collegato di Trento) (Italy); Bagolini, A.; Boscardin, M. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi (FBK-CMM), Via Sommarive, 18, I-38123 Povo di Trento (Italy); Dalla Betta, G.-F. [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento, Via Sommarive, 14, I-38123 Povo di Trento (Italy); INFN, Sezione di Padova (Gruppo Collegato di Trento) (Italy); Giacomini, G.; Vianello, E.; Zorzi, N. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi (FBK-CMM), Via Sommarive, 18, I-38123 Povo di Trento (Italy)
2011-12-01
We report on the first batch of planar active edge sensors fabricated at Fondazione Bruno Kessler (Trento, Italy) on the way to the development of full 3D detectors with active edges. The main design and technological aspects are reported, along with selected results from the electrical characterization of detectors and test structures.
Are ghosts necessary in planar gauges?
International Nuclear Information System (INIS)
Kummer, W.
1988-01-01
The introduction of Faddeev-Popov ghosts in axial gauges and especially in the ones of the planar type is not a technical necessity for the general proof of renormalization and gauge independence. It is shown that all necessary identities for Green's functions and for one-particle-irreducible vertices arise in a completely ghost-free formulation as well
Planar chromatography coupled with spectroscopic techniques.
Somsen, G.W.; Wilson, I.D.; Morden, W.
1995-01-01
Recent progress in the combination of planar, or thin-layer chromatography (TLC) with a variety of modern spectroscopic techniques is reviewed. The utility of TLC for separation followed by mass spectrometry, with a variety of ionisation techniques, is illustrated with reference to a wide range of
Functional planar thin film optical waveguide lasers
Czech Academy of Sciences Publication Activity Database
Jelínek, Miroslav
2012-01-01
Roč. 9, č. 2 (2012), 91-99 ISSN 1612-2011 R&D Projects: GA ČR(CZ) GAP106/10/1477 Institutional research plan: CEZ:AV0Z10100522 Keywords : waveguide laser * planar waveguides * thin films * pulsed laser deposition * optical waveguides * laser materials Subject RIV: BH - Optics, Masers, Lasers Impact factor: 7.714, year: 2012
EPU correction scheme study at the CLS
Energy Technology Data Exchange (ETDEWEB)
Bertwistle, Drew, E-mail: drew.bertwistle@lightsource.ca; Baribeau, C.; Dallin, L.; Chen, S.; Vogt, J.; Wurtz, W. [Canadian Light Source Inc. 44 Innovation Boulevard, Saskatoon, SK S7N 2V3 (Canada)
2016-07-27
The Canadian Light Source (CLS) Quantum Materials Spectroscopy Center (QMSC) beamline will employ a novel double period (55 mm, 180 mm) elliptically polarizing undulator (EPU) to produce photons of arbitrary polarization in the soft X-ray regime. The long period and high field of the 180 mm period EPU will have a strong dynamic focusing effect on the storage ring electron beam. We have considered two partial correction schemes, a 4 m long planar array of BESSY-II style current strips, and soft iron L-shims. In this paper we briefly consider the implementation of these correction schemes.
Nanopatterning planar and non-planar mold surfaces for a polymer replication
DEFF Research Database (Denmark)
Cech, Jiri; Pranov, Henrik; Kofod, Guggi
2013-01-01
We present a novel process to create nanopatterns on planar and non-planar polymer replication tools, such as metallic molds for an injection molding. Such tools with nanopatterned cavities then allow affordable mass production of nanopatterned polymer parts with inherent advanced functionalities...... energy and sticktion and to facilitate de-molding of plastic parts.1 This allows forming of affordable plastic parts with advanced functionality.......We present a novel process to create nanopatterns on planar and non-planar polymer replication tools, such as metallic molds for an injection molding. Such tools with nanopatterned cavities then allow affordable mass production of nanopatterned polymer parts with inherent advanced functionalities...... such as low reflectivity or color effects, self cleaning, superhydrofobicity, antifouling, etc, all created in a single injection molding cycle. Presented process is based on the classic cleanroom microfabrication of micro/nano patterns, nickel electroplating and template removal to form a flexible...
Searching for planar signatures in WMAP
International Nuclear Information System (INIS)
Abramo, L. Raul; Bernui, Armando; Pereira, Thiago S.
2009-01-01
We search for planar deviations of statistical isotropy in the Wilkinson Microwave Anisotropy Probe (WMAP) data by applying a recently introduced angular-planar statistics both to full-sky and to masked temperature maps, including in our analysis the effect of the residual foreground contamination and systematics in the foreground removing process as sources of error. We confirm earlier findings that full-sky maps exhibit anomalies at the planar (l) and angular (l) scales (l,l) = (2,5),(4,7), and (6,8), which seem to be due to unremoved foregrounds since this features are present in the full-sky map but not in the masked maps. On the other hand, our test detects slightly anomalous results at the scales (l,l) = (10,8) and (2,9) in the masked maps but not in the full-sky one, indicating that the foreground cleaning procedure (used to generate the full-sky map) could not only be creating false anomalies but also hiding existing ones. We also find a significant trace of an anomaly in the full-sky map at the scale (l,l) = (10,5), which is still present when we consider galactic cuts of 18.3% and 28.4%. As regards the quadrupole (l = 2), we find a coherent over-modulation over the whole celestial sphere, for all full-sky and cut-sky maps. Overall, our results seem to indicate that current CMB maps derived from WMAP data do not show significant signs of anisotropies, as measured by our angular-planar estimator. However, we have detected a curious coherence of planar modulations at angular scales of the order of the galaxy's plane, which may be an indication of residual contaminations in the full- and cut-sky maps
ytterbium- & erbium-doped silica for planar waveguide lasers & amplifiers
DEFF Research Database (Denmark)
Dyndgaard, Morten Glarborg
2001-01-01
The purpose of this work was to demonstrate ytterbium doped planar components and investigate the possibilities of making erbium/ytterbium codoped planar waveguides in germano-silica glass. Furthermore, tools for modelling lasers and erbium/ytterbium doped amplifiers. The planar waveguides were...
Overview of Planar Magnetic Technology — Fundamental Properties
DEFF Research Database (Denmark)
Ouyang, Ziwei; Andersen, Michael A. E.
2014-01-01
advantages and disadvantages in the use of planar magnetics for high frequency power converters are covered, and publications on planar magnetics are reviewed. A detailed survey of winding conduction loss, leakage inductance and winding capacitance for planar magnetics is presented so power electronics...
Holographic bulk reconstruction with α' corrections
Roy, Shubho R.; Sarkar, Debajyoti
2017-10-01
We outline a holographic recipe to reconstruct α' corrections to anti-de Sitter (AdS) (quantum) gravity from an underlying CFT in the strictly planar limit (N →∞ ). Assuming that the boundary CFT can be solved in principle to all orders of the 't Hooft coupling λ , for scalar primary operators, the λ-1 expansion of the conformal dimensions can be mapped to higher curvature corrections of the dual bulk scalar field action. Furthermore, for the metric perturbations in the bulk, the AdS /CFT operator-field isomorphism forces these corrections to be of the Lovelock type. We demonstrate this by reconstructing the coefficient of the leading Lovelock correction, also known as the Gauss-Bonnet term in a bulk AdS gravity action using the expression of stress-tensor two-point function up to subleading order in λ-1.
Phase error correction in wavefront curvature sensing via phase retrieval
DEFF Research Database (Denmark)
Almoro, Percival; Hanson, Steen Grüner
2008-01-01
Wavefront curvature sensing with phase error correction system is carried out using phase retrieval based on a partially-developed volume speckle field. Various wavefronts are reconstructed: planar, spherical, cylindrical, and a wavefront passing through the side of a bare optical fiber. Spurious...
Topological quantum error correction with optimal encoding rate
International Nuclear Information System (INIS)
Bombin, H.; Martin-Delgado, M. A.
2006-01-01
We prove the existence of topological quantum error correcting codes with encoding rates k/n asymptotically approaching the maximum possible value. Explicit constructions of these topological codes are presented using surfaces of arbitrary genus. We find a class of regular toric codes that are optimal. For physical implementations, we present planar topological codes
Planar chiral metamaterials for biosensing applications
Murugkar, Sangeeta; De Leon, Israel; Horton, Matthew; Qassim, Hammam; Leach, Jonathan; Boyd, Robert W.
2013-02-01
There has been a considerable effort recently in the development of planar chiral metamaterials. Owing to the lack of inversion symmetry, these materials have been shown to display interesting physical properties such as negative index of refraction and giant optical activity. However, the biosensing capabilities of these chiral metamaterials have not been fully explored. Ultrasensitive detection and structural characterization of proteins adsorbed on chiral plasmonic substrates was demonstrated recently using UV-visible circular dichroism (CD) spectroscopy. Second harmonic generation microscopy is an extremely sensitive nonlinear optical probe to investigate the chirality of biomaterials. In this study, we characterize the chiral response of chiral plasmonic metamaterials using second harmonic generation microscopy and CD spectroscopy. These planar chiral metamaterials, fabricated by electron-beam lithography, consist of right-handed and left-handed gold gammadions of length 400 nm and thickness 100nm, deposited on a glass substrate and arranged in a square lattice with a periodicity of 800nm.
Planar elongation of soft polymeric networks
DEFF Research Database (Denmark)
Jensen, Mette Krog; Hassager, Ole; Rasmussen, Henrik K.
2010-01-01
A new test fixture for the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks with application towards pressure-sensitive adhesives (PSAs). The concept of this new geometry is to elongate a tube-like sample by keeping the perimeter constant....... To validate this new technique, soft polymeric networks of poly(propylene oxide) (PPO) were investigated during deformation. Particle tracking and video recording were used to detect to what extent the imposed strain rate and the sample perimeter remained constant. It was observed that, by using...... an appropriate choice of initial sample height, perimeter, and thickness, the planar stretch ratio will follow lambda(t) = h(t)/h(0) = exp((epsilon)overdot t), with h(t) being the height at time t and (epsilon)overdot the imposed constant strain rate. The perimeter would decrease by a few percent only, which...
Position Analysis of Planar Tensegrity Structures
2006-08-01
and 2 non-compliant members. Finding a simple solution approach for a closed form solution to the other two dimensional tensegrity structures...dimensional tensegrity structures, struts still do not touch. A tensegrity structure stands by itself in its equilibrium position and maintains its form ...equilibrium position when no external force or torque is applied. A closed- form solution of a two-spring, three-spring, and four- spring planar tensegrity
Planar graphical models which are easy
Energy Technology Data Exchange (ETDEWEB)
Chertkov, Michael [Los Alamos National Laboratory; Chernyak, Vladimir [WAYNE STATE UNIV
2009-01-01
We describe a rich family of binary variables statistical mechanics models on planar graphs which are equivalent to Gaussian Grassmann Graphical models (free fermions). Calculation of partition function (weighted counting) in the models is easy (of polynomial complexity) as reduced to evaluation of determinants of matrixes linear in the number of variables. In particular, this family of models covers Holographic Algorithms of Valiant and extends on the Gauge Transformations discussed in our previous works.
UWB and SWB Planar Antenna Technology
Zhong, Shun-Shi
2010-01-01
The recent progress in the development of UWB planar antenna technology has been reviewed. Some types of UWB metal-plate monopole antennas, UWB printed monopole antennas and UWB printed slot antennas are presented. The comparison results of indicate that the UWB printed monopole antennas can realize relatively smaller dimensions, and that the UWB printed slot antennas can achieve relatively higher gain. Finally, some realization manners of the band-notch function of UWB printed monopole anten...
High-performance planar nanoscale dielectric capacitors
Ciraci, S.; Özçelik, V. Ongun
2016-01-01
We propose a model for planar nanoscale dielectric capacitor consisting of a single layer, insulating hexagonal boron nitride (BN) stripe placed between two metallic graphene stripes, all forming commensurately a single atomic plane. First-principles density functional calculations on these nanoscale capacitors for different levels of charging and different widths of graphene - BN stripes mark high gravimetric capacitance values, which are comparable to those of supercapacitors made from othe...
Hairy planar black holes in higher dimensions
International Nuclear Information System (INIS)
Aceña, Andrés; Anabalón, Andrés; Astefanesei, Dumitru; Mann, Robert
2014-01-01
We construct exact hairy planar black holes in D-dimensional AdS gravity. These solutions are regular except at the singularity and have stress-energy that satisfies the null energy condition. We present a detailed analysis of their thermodynamical properties and show that the first law is satisfied. We also discuss these solutions in the context of AdS/CFT duality and construct the associated c-function
Determinantal spanning forests on planar graphs
Kenyon, Richard
2017-01-01
We generalize the uniform spanning tree to construct a family of determinantal measures on essential spanning forests on periodic planar graphs in which every component tree is bi-infinite. Like the uniform spanning tree, these measures arise naturally from the laplacian on the graph. More generally these results hold for the "massive" laplacian determinant which counts rooted spanning forests with weight $M$ per finite component. These measures typically have a form of conformal invariance, ...
Hairy planar black holes in higher dimensions
Energy Technology Data Exchange (ETDEWEB)
Aceña, Andrés [Instituto de Ciencias Básicas, Universidad Nacional de Cuyo,Mendoza (Argentina); Anabalón, Andrés [Departamento de Ciencias, Facultad de Artes Liberales y Facultad de Ingeniería y Ciencias,Universidad Adolfo Ibáñez, Viña del Mar (Chile); Université de Lyon, Laboratoire de Physique,UMR 5672, CNRS, École Normale Supérieure de Lyon,46 allé d’Italie, F-69364 Lyon Cedex 07 (France); Astefanesei, Dumitru [Instituto de Física, Pontificia Universidad Católica de Valparaíso,Casilla 4059, Valparaíso (Chile); Mann, Robert [Department of Physics and Astronomy, University of Waterloo,Waterloo, Ontario, N2L 3G1 (Canada); Perimeter Institute,31 Caroline Street North Waterloo, Ontario N2L 2Y5 (Canada)
2014-01-28
We construct exact hairy planar black holes in D-dimensional AdS gravity. These solutions are regular except at the singularity and have stress-energy that satisfies the null energy condition. We present a detailed analysis of their thermodynamical properties and show that the first law is satisfied. We also discuss these solutions in the context of AdS/CFT duality and construct the associated c-function.
Modeling and optimization of planar microcoils
International Nuclear Information System (INIS)
Beyzavi, Ali; Nguyen, Nam-Trung
2008-01-01
Magnetic actuation has emerged as a useful tool for manipulating particles, droplets and biological samples in microfluidics. A planar coil is one of the suitable candidates for magnetic actuation and has the potential to be integrated in digital microfluidic devices. A simple model of microcoils is needed to optimize their use in actuation applications. This paper first develops an analytical model for calculating the magnetic field of a planar microcoil. The model was validated by experimental data from microcoils fabricated on printed circuit boards (PCB). The model was used for calculating the field strength and the force acting on a magnetic object. Finally, the effect of different coil parameters such as the magnitude of the electric current, the gap between the wires and the number of wire segments is discussed. Both analytical and experimental results show that a smaller gap size between wire segments, more wire segments and a higher electric current can increase both the magnitude and the gradient of the magnetic field, and consequently cause a higher actuating force. The planar coil analyzed in the paper is suitable for applications in magnetic droplet-based microfluidics
Personal audio with a planar bright zone.
Coleman, Philip; Jackson, Philip J B; Olik, Marek; Pedersen, Jan Abildgaard
2014-10-01
Reproduction of multiple sound zones, in which personal audio programs may be consumed without the need for headphones, is an active topic in acoustical signal processing. Many approaches to sound zone reproduction do not consider control of the bright zone phase, which may lead to self-cancellation problems if the loudspeakers surround the zones. Conversely, control of the phase in a least-squares sense comes at a cost of decreased level difference between the zones and frequency range of cancellation. Single-zone approaches have considered plane wave reproduction by focusing the sound energy in to a point in the wavenumber domain. In this article, a planar bright zone is reproduced via planarity control, which constrains the bright zone energy to impinge from a narrow range of angles via projection in to a spatial domain. Simulation results using a circular array surrounding two zones show the method to produce superior contrast to the least-squares approach, and superior planarity to the contrast maximization approach. Practical performance measurements obtained in an acoustically treated room verify the conclusions drawn under free-field conditions.
Two-loop statsum of superstrings
Morozov, A.
1988-06-01
We discuss, whether there is a choice of odd moduli on super-Riemann surfaces of genus p≳2, which leads to the vanishing of statistical sums of superstrings before integration over the space of even moduli. The answer is shown to be positive at least for p=2, when odd moduli are localized at ramification points. The relation between various definitions of many-loop statistical sums in superstring theory is discussed.
Monte Carlo method for critical systems in infinite volume: The planar Ising model.
Herdeiro, Victor; Doyon, Benjamin
2016-10-01
In this paper we propose a Monte Carlo method for generating finite-domain marginals of critical distributions of statistical models in infinite volume. The algorithm corrects the problem of the long-range effects of boundaries associated to generating critical distributions on finite lattices. It uses the advantage of scale invariance combined with ideas of the renormalization group in order to construct a type of "holographic" boundary condition that encodes the presence of an infinite volume beyond it. We check the quality of the distribution obtained in the case of the planar Ising model by comparing various observables with their infinite-plane prediction. We accurately reproduce planar two-, three-, and four-point of spin and energy operators. We also define a lattice stress-energy tensor, and numerically obtain the associated conformal Ward identities and the Ising central charge.
Digital image processing of saturation for two-phase flow in planar porous media model
Directory of Open Access Journals (Sweden)
Zhi Dou
2012-06-01
Full Text Available In this paper, the accuracy of estimating stained non-wetting phase saturation using digital image processing is examined, and a novel post-processing approach for calculating threshold is presented. In order to remove the effect of the background noise of images and to enhance the high-frequency component of the original image, image smoothing and image sharpening methods are introduced. Depending on the correct threshold, the image binarization processing is particularly useful for estimating stained non-wetting phase saturation. Calculated saturation data are compared with the measured saturation data during the two-phase flow experiment in an artificial steel planar porous media model. The results show that the calculated saturation data agree with the measured ones. With the help of an artificial steel planar porous media model, digital image processing is an accurate and simple method for obtaining the stained non-wetting phase saturation.
A line-based spectral clustering method for efficient planar structure extraction from LiDAR data
Directory of Open Access Journals (Sweden)
Y. He
2013-10-01
Full Text Available Planar structures are essential components of the urban landscape and automated extraction planar structure from LiDAR data is a fundamental step in solving complex mapping tasks such as building recognition and urban modelling. This paper presents a new and effective method for planar structure extraction from airborne LiDAR data based on spectral clustering of straight line segments. The straight line segments are derived from LiDAR scan lines using an Iterative-End-Point-Fit simplification algorithm. Adjacency matrix is then formed based on pair-wise similarity of the extracted line segments, and a symmetric affine matrix is derived which is then decomposed into eigenspace. The planar structures are then detected by mean-shift clustering algorithm in eigenspace. The use of straight line segments facilitates the processing and significantly reduces the computational load. Spectral analysis of straight line segments in eigenspace makes the planar structures more prominent, resulting in a robust extraction of planar surfaces. Experiments are performed on the ISPRS benchmark LiDAR data over three test sites containing a variety of buildings with complex roof structures and varying sizes. The experimental results, which are quantitatively evaluated independently by the ISPRS benchmark test group, are presented. The results show that the proposed method achieves on average 80% of completeness with over 98% of correctness. Better performance is observed over larger size of buildings (>10m2 with over 92% of completeness and nearly 100% of correctness in all test areas, indicating the robustness and high reliability of the proposed algorithm.
Broadband Planar 5:1 Impedence Transformer
Ehsan, Negar; Hsieh, Wen-Ting; Moseley, Samuel H.; Wollack, Edward J.
2015-01-01
This paper presents a broadband Guanella-type planar impedance transformer that transforms so 50 omega to 10 omega with a 10 dB bandwidth of 1-14GHz. The transformer is designed on a flexible 50 micrometer thick polyimide substrate in microstrip and parallel-plate transmission line topologies, and is Inspired by the traditional 4:1 Guanella transformer. Back-to-back transformers were designed and fabricated for characterization in a 50 omega system. Simulated and measured results are in excellent agreement.
Optical planar waveguide for cell counting
LeBlanc, John; Mueller, Andrew J.; Prinz, Adrian; Butte, Manish J.
2012-01-01
Low cost counting of cells has medical applications in screening, military medicine, disaster medicine, and rural healthcare. In this report, we present a shallow, buried, planar waveguide fabricated by potassium ion exchange in glass that enables low-cost and rapid counting of metal-tagged objects that lie in the evanescent field of the waveguide. Laser light transmitted through the waveguide was attenuated proportionately to the presence of metal-coated microstructures fabricated from photoresist. This technology enables the low-cost enumeration of cells from blood, urine, or other biofluids.
Planar domain walls in black hole spacetimes
Ficek, Filip; Mach, Patryk
2018-02-01
We investigate the behavior of low-mass, planar domain walls in the so-called ϕ4 model of the scalar field on the Schwarzschild and Kerr backgrounds. We focus on a transit of a domain wall through a black hole and solve numerically the equations of motion for a range of parameters of the domain wall and the black hole. We observe a behavior resembling an occurrence of ringing modes. Perturbations of domain walls vanish during latter evolution, suggesting their stability against a passage through the black hole. The results obtained for Kerr and Reissner-Nordström black holes are also compared.
Theoretical analysis of planar pulse microwiggler
Energy Technology Data Exchange (ETDEWEB)
Qing-Xiang Liu [Institute of Applied Electronics, Sichuan (China)]|[Southwest Jiaotong Univ., Sichuan (China); Yong Xu [Southwest Jiatong Univ., Sichuan (China)
1995-12-31
The Magnetic field distributions of a planar pulse microwiggler are studied analytically and numerically. Exact solutions of two-dimensional magnetic fields are derived, which show that along the electron axis the fields have a variation close enough to a sine wave. We also investigate wiggler field errors due to machining tolerance and effects of the field errors on trajectories of electron with the help numerical simulations. The results are critical for successful operation of CAEP compact free-electron laser experiment under preparation.
Some remarks on non-planar Feynman diagrams
Energy Technology Data Exchange (ETDEWEB)
Bielas, Krzysztof; Dubovyk, Ievgen; Gluza, Janusz [Silesia Univ., Katowice (Poland). Inst. of Physics; Riemann, Tord [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2013-12-15
Two criteria for planarity of a Feynman diagram upon its propagators (momentum ows) are presented. Instructive Mathematica programs that solve the problem and examples are provided. A simple geometric argument is used to show that while one can planarize non-planar graphs by embedding them on higher-genus surfaces (in the example it is a torus), there is still a problem with defining appropriate dual variables since the corresponding faces of the graph are absorbed by torus generators.
Multistability in planar liquid crystal wells
Luo, Chong
2012-06-08
A planar bistable liquid crystal device, reported in Tsakonas, is modeled within the Landau-de Gennes theory for nematic liquid crystals. This planar device consists of an array of square micrometer-sized wells. We obtain six different classes of equilibrium profiles and these profiles are classified as diagonal or rotated solutions. In the strong anchoring case, we propose a Dirichlet boundary condition that mimics the experimentally imposed tangent boundary conditions. In the weak anchoring case, we present a suitable surface energy and study the multiplicity of solutions as a function of the anchoring strength. We find that diagonal solutions exist for all values of the anchoring strength W≥0, while rotated solutions only exist for W≥W c>0, where W c is a critical anchoring strength that has been computed numerically. We propose a dynamic model for the switching mechanisms based on only dielectric effects. For sufficiently strong external electric fields, we numerically demonstrate diagonal-to-rotated and rotated-to-diagonal switching by allowing for variable anchoring strength across the domain boundary. © 2012 American Physical Society.
General lossless planar coupler design algorithms.
Vance, Rod
2015-08-01
This paper reviews and extends two classes of algorithms for the design of planar couplers with any unitary transfer matrix as design goals. Such couplers find use in optical sensing for fading free interferometry, coherent optical network demodulation, and also for quantum state preparation in quantum optical experiments and technology. The two classes are (1) "atomic coupler algorithms" decomposing a unitary transfer matrix into a planar network of 2×2 couplers, and (2) "Lie theoretic algorithms" concatenating unit cell devices with variable phase delay sets that form canonical coordinates for neighborhoods in the Lie group U(N), so that the concatenations realize any transfer matrix in U(N). As well as review, this paper gives (1) a Lie theoretic proof existence proof showing that both classes of algorithms work and (2) direct proofs of the efficacy of the "atomic coupler" algorithms. The Lie theoretic proof strengthens former results. 5×5 couplers designed by both methods are compared by Monte Carlo analysis, which would seem to imply atomic rather than Lie theoretic methods yield designs more resilient to manufacturing imperfections.
Optical magnetism in planar metamaterial heterostructures.
Papadakis, Georgia T; Fleischman, Dagny; Davoyan, Artur; Yeh, Pochi; Atwater, Harry A
2018-01-18
Harnessing artificial optical magnetism has previously required complex two- and three-dimensional structures, such as nanoparticle arrays and split-ring metamaterials. By contrast, planar structures, and in particular dielectric/metal multilayer metamaterials, have been generally considered non-magnetic. Although the hyperbolic and plasmonic properties of these systems have been extensively investigated, their assumed non-magnetic response limits their performance to transverse magnetic (TM) polarization. We propose and experimentally validate a mechanism for artificial magnetism in planar multilayer metamaterials. We also demonstrate that the magnetic properties of high-index dielectric/metal hyperbolic metamaterials can be anisotropic, leading to magnetic hyperbolic dispersion in certain frequency regimes. We show that such systems can support transverse electric polarized interface-bound waves, analogous to their TM counterparts, surface plasmon polaritons. Our results open a route for tailoring optical artificial magnetism in lithography-free layered systems and enable us to generalize the plasmonic and hyperbolic properties to encompass both linear polarizations.
Normal planar undulators doubling as transverse gradient undulators
Directory of Open Access Journals (Sweden)
Qika Jia
2017-02-01
Full Text Available The transverse gradient undulator (TGU has important application in the short-wavelength high-gain free electron lasers (FELs driven by laser-plasma accelerators. However, the usual transversely tapered TGUs need special design and manufacture, and the transverse gradient cannot be tuned arbitrarily. In this paper we explore a new and simple method of using the natural transverse gradient of a normal planar undulator to compensate the beam energy spread effect. In this method, a vertical dispersion on the electron beam is introduced, then the dispersed beam passes through a normal undulator with a vertical off-axis orbit where the vertical field gradient is selected properly related to the dispersion strength and the beam energy spread. Theoretical analysis and numerical simulations for self-amplified spontaneous emission FELs based on laser plasma accelerators are presented, and indicate that this method can greatly reduce the effect of the beam energy spread, leading to a similar enhancement on FEL performance as the usual transversely tapered TGU, but with the advantages of economy, tunable transverse gradient and no demand of extra field for correcting the orbit deflection induced by the field gradient.
Improvement of planar laser diagnostics by the application of a beam homogenizer
International Nuclear Information System (INIS)
Pfadler, S; Loeffler, M; Beyrau, F; Leipertz, A
2007-01-01
For planar laser diagnostics, a most uniform beam profile is highly desirable for two reasons: first, subsequent corrections for an inhomogeneous intensity distribution are time consuming and prevent on-line engineering assessment and second, temporal fluctuations cannot be corrected anyway. However, in general for combustion and flow diagnostics pulsed laser sources are used to achieve a high temporal resolution which typically possess a rather poor beam quality compared to continuously emitting laser sources. And, pulse to pulse fluctuations of the beam profile directly increase the noise in single-shot measurements. In this contribution we show the application of a micro-lens array based beam homogenizer whereby an almost homogeneous illumination of the region of in interest is achieved. This enables the on-line evaluation of the measured data without subsequent corrections. Thus a general advance of laser techniques towards engineering practice is achieved. Additionally, statistical fluctuations of the beam profile are strongly reduced by the homogenizer what directly improves the local standard deviation of the measurement. These benefits are demonstrated by means of planar laser-induced fluorescence (LIF) experiments
Diffusion-weighted multiple shot echo planar imaging of humans without navigation.
Robson, M D; Anderson, A W; Gore, J C
1997-07-01
A new method is proposed for reducing the artifacts produced in diffusion-weighted imaging. When data are acquired using multiple shot echo planar acquisitions, conventional reconstruction methods produce artifactual images as a consequence of diffusion weighting and small amounts of bulk motion of the subject. If the amount of motion can be determined, it is possible to correct the data before reconstruction, which removes the artifact. A method for estimating the motion from the acquired data has been developed and evaluated. This method assumes that ghost image effects will be minimized when motion has been correctly compensated. By considering the amount of signal in the background of the image, appropriate corrections to the data can be made, and the accuracy of the motion compensation may be estimated. This technique has been evaluated by computer simulation, and its performance has been demonstrated in a phantom and humans with both two- and four-shot echo planar acquisitions and using both "mosaic" and "interleaved" sampling schemes.
78 FR 75449 - Miscellaneous Corrections; Corrections
2013-12-12
... cross- references, correcting grammatical errors, revising language for clarity and consistency, and... practice. Specifically, these amendments are to correct grammatical errors and to revise cross-references.... The final rule contained minor errors in grammar, punctuation, and referencing. This document corrects...
PET phantom design for assessment of quantitative imaging of arbitrary planar distributions
Energy Technology Data Exchange (ETDEWEB)
Markiewicz, P.J.; Angelis, G.I.; Kotasidis, F.; Matthews, J.C. [Manchester Univ. (United Kingdom). School of Cancer and Enabling Sciences; Lionheart, W.R. [Manchester Univ. (United Kingdom). School of Mathematics; Reader, A.J. [McGill Univ., Montreal, QC (Canada). Brain Imaging Centre
2011-07-01
A specially designed phantom enabling development and evaluation of reconstruction methods and system models for the high resolution research tomograph (HRRT) is here presented. The design of the phantom permits for planar sources of any spatial radioactivity distribution to be imaged in transaxial and axial (sagittal/coronal) planes. The planar sources are created by feeding A4 paper sheets into an ink-jet printer with a modified cartridge containing ink mixed with a given radioisotope (usually 18F). Phosphor imaging plates (IP) are used with computed radiography (CR) to assess the quality of the printing and also to provide a gold standard with which the reconstructed HRRT data can be compared. For further quantitative testing and analysis a number of equally-sized samples are cut out from the planar sources and measured in a well counter. Using such a custombuild phantom not only avoids the scatter correction problem (scatter is then negligible) but may also enable development of more complex models, methods or reconstruction techniques which are of critical importance in high resolution iterative image reconstruction. Presented results demonstrate good quantitative agreement between the HRRT, CR and well counter. (orig.)
Development of Osaka gas type planar SOFC
Energy Technology Data Exchange (ETDEWEB)
Iha, M.; Shiratori, A.; Chikagawa, O. [Murata Mfg. Co., Ltd., Shiga (Japan)] [and others
1996-12-31
Osaka Gas Co. has been developing a planar type SOFC (OG type SOFC) which has a suitable structure for stacking. Murata Mfg. Co. has begun to develop the OG type SOFC stack through joint program since 1993. Figure 1 shows OG type cell structure. Because each cell is sustained by cell holders acting air manifold, the load of upper cell is not put on the lower cells. Single cell is composed of 3-layered membrane and LaCrO{sub 3} separator. 5 single cells are mounted on the cell holder, connected with Ni felt electrically, and bonded by glassy material sealant. We call the 5-cell stack a unit. Stacking 13 units, we succeeded 870 W generation in 1993. But the power density was low, 0.11 Wcm{sup -2} because of crack in the electrolyte and gas leakage at some cells.
Cell Proliferation on Planar and Curved Substrates
Gaines, Michelle; Chang, Ya Wen; Cruz, Ricardo; Fragkopoulos, Alexandros; Garcia, Andres; Fernandez-Nieves, Alberto
Aberrant epithelial collective cell growth is one of the major challenges to be addressed in order to treat diseases such as cancer and organ fibrosis. The conditions of the extracellular microenvironment, properties of the cells' cytoskeleton, and interfacial properties of the substratum (the surface in contact with epithelial cells) have a significant influence on the migratory behavior of epithelial cells, cell proliferation and migration. This work focuses on understanding the impact the substratum curvature has on cell behavior. We focus on cell proliferation first and study MDCK cells on both planar and curved hydrogel substrates. The curved hydrogels are based on polyacrylamide and have toroidal shape, with tube radius 200 um and an aspect ratio in the rage between 2 and 9. Proliferation is measured using the Click-it EDU assay (Invitrogen), which measures cells that are synthesizing DNA. Funding Source is Childrens Healthcare of Atlanta.
Anions, quantum particles in planar systems
International Nuclear Information System (INIS)
Monerat, Germano Amaral
2000-03-01
Our purpose here is to present a general review of the non-relativistic quantum-mechanical description of excitations that do not obey neither the Fermi-Dirac nor the Bose-Einstein statistics; they rather fulfill an intermediate statistics, the we called 'any-statistics'. As we shall see, this is a peculiarity of (1+1) and (1+2) dimensions, due to the fact that, in two space dimensions, the spin is not quantised, once the rotation group is Abelian. The relevance of studying theories in (1+2) dimensions is justified by the evidence that, in condensed matter physics, there are examples of planar systems, for which everything goes as if the third spatial dimension is frozen. (author)
Planar Silicon Optical Waveguide Light Modulators
DEFF Research Database (Denmark)
Leistiko, Otto; Bak, H.
1994-01-01
that values in the nanosecond region should be possible, however, the measured values are high, 20 microseconds, due to the large area of the injector junctions, 1Ã— 10Â¿2 cm2, and the limitations imposed by the detection circuit. The modulating properties of these devices are impressive, measurements......The results of an experimental investigation of a new type of optical waveguide based on planar technology in which the liglht guiding and modulation are achieved by exploiting free carrier effects in silicon are presented. Light is guided between the n+ substrate and two p+ regions, which also...... serve as carrier injectors for controling absorption. Light confinement of single mode devices is good, giving spot sizes of 9 Â¿m FWHM. Insertion loss measurements indicate that the absorption losses for these waveguides are extremely low, less 1 dB/cm. Estimates of the switching speed indicate...
A planar quasi-optical SIS receiver
Stimson, Philip A.; Dengler, Robert J.; Leduc, Henry G.; Cypher, Scott R.; Siegel, Peter H.
1993-01-01
A planar, quasi-optical SIS receiver operating at 230 GHz is described. The receiver consists of a 2 x 5 array of half wave dipole antennas with ten niobium-aluminum oxide-niobium SIS junctions on a quartz dielectric-filled parabola. The 1.4 GHz intermediate frequency is coupled from the mixer via coplanar strip transmission lines and 4:1 balun transformers. The receiver is operated at 4.2 K in a liquid helium immersion cryostat. We report accurate measurements of the performance of single receiver elements. A mixer noise temperature of 89 K DSB, receiver noise temperature of 156 K DSB, and conversion loss of 3 dB into a matched load have been obtained.
Terahertz planar antennas for next generation communication
Jha, Kumud Ranjan
2014-01-01
This book describes various methods to enhance the directivity of planar antennas, enabling the next generation of high frequency, wireless communication. The authors discuss various applications to the terahertz regime of the electromagnetic spectrum, with an emphasis on gain enhancement mechanisms. The numerical models of these antennas are presented and the analytical results are supported, using commercial simulators. The multilayer substrate microstrip transmission line at terahertz frequency is also explored and a method to obtain the various parameters of this interconnect at high frequency is described. This book will be a valuable resource for anyone needing to explore the terahertz band gap for future wireless communication, in an effort to solve the bandwidth (spectrum scarcity) problem. • Enables development of terahertz communication systems in a license-free band of the electromagnetic spectrum; • Describes methods to design a multi-layered substrate transmission line to reduce var...
Organic hybrid planar-nanocrystalline bulk heterojunctions
Forrest, Stephen R [Ann Arbor, MI; Yang, Fan [Piscataway, NJ
2011-03-01
A photosensitive optoelectronic device having an improved hybrid planar bulk heterojunction includes a plurality of photoconductive materials disposed between the anode and the cathode. The photoconductive materials include a first continuous layer of donor material and a second continuous layer of acceptor material. A first network of donor material or materials extends from the first continuous layer toward the second continuous layer, providing continuous pathways for conduction of holes to the first continuous layer. A second network of acceptor material or materials extends from the second continuous layer toward the first continuous layer, providing continuous pathways for conduction of electrons to the second continuous layer. The first network and the second network are interlaced with each other. At least one other photoconductive material is interspersed between the interlaced networks. This other photoconductive material or materials has an absorption spectra different from the donor and acceptor materials.
Recognition of Planar Objects Using Multiresolution Analysis
Directory of Open Access Journals (Sweden)
Ayşın Ertüzün
2007-01-01
Full Text Available By using affine-invariant shape descriptors, it is possible to recognize an unknown planar object from an image taken from an arbitrary view when standard view images of candidate objects exist in a database. In a previous study, an affine-invariant function calculated from the wavelet coefficients of the object boundary has been proposed. In this work, the invariant is constructed from the multiwavelet and (multiscaling function coefficients of the boundary. Multiwavelets are known to have superior performance compared to scalar wavelets in many areas of signal processing due to their simultaneous orthogonality, symmetry, and short support properties. Going from scalar wavelets to multiwavelets is challenging due to the increased dimensionality of multiwavelets. This increased dimensionality is exploited to construct invariants with better performance when the multiwavelet “detail” coefficients are available. However, with (multiscaling function coefficients, which are more stable in the presence of noise, scalar wavelets cannot be defeated.
Recognition of Planar Objects Using Multiresolution Analysis
Directory of Open Access Journals (Sweden)
Güney Nazlı
2007-01-01
Full Text Available By using affine-invariant shape descriptors, it is possible to recognize an unknown planar object from an image taken from an arbitrary view when standard view images of candidate objects exist in a database. In a previous study, an affine-invariant function calculated from the wavelet coefficients of the object boundary has been proposed. In this work, the invariant is constructed from the multiwavelet and (multiscaling function coefficients of the boundary. Multiwavelets are known to have superior performance compared to scalar wavelets in many areas of signal processing due to their simultaneous orthogonality, symmetry, and short support properties. Going from scalar wavelets to multiwavelets is challenging due to the increased dimensionality of multiwavelets. This increased dimensionality is exploited to construct invariants with better performance when the multiwavelet "detail" coefficients are available. However, with (multiscaling function coefficients, which are more stable in the presence of noise, scalar wavelets cannot be defeated.
Renormalization of QED with planar binary trees
International Nuclear Information System (INIS)
Brouder, C.
2001-01-01
The Dyson relations between renormalized and bare photon and electron propagators Z 3 anti D(q)=D(q) and Z 2 anti S(q)=S(q) are expanded over planar binary trees. This yields explicit recursive relations for the terms of the expansions. When all the trees corresponding to a given power of the electron charge are summed, recursive relations are obtained for the finite coefficients of the renormalized photon and electron propagators. These relations significantly decrease the number of integrals to carry out, as compared to the standard Feynman diagram technique. In the case of massless quantum electrodynamics (QED), the relation between renormalized and bare coefficients of the perturbative expansion is given in terms of a Hopf algebra structure. (orig.)
Discrete approach to complex planar geometries
International Nuclear Information System (INIS)
Cupini, E.; De Matteis, A.
1974-01-01
Planar regions in Monte Carlo transport problems have been represented by a finite set of points with a corresponding region index for each. The simulation of particle free-flight reduces then to the simple operations necessary for scanning appropriate grid points to determine whether a region other than the starting one is encountered. When the complexity of the geometry is restricted to only some regions of the assembly examined, a mixed discrete-continuous philosophy may be adopted. By this approach, the lattice of a thermal reactor has been treated, discretizing only the central regions of the cell containing the fuel rods. Excellent agreement with experimental results has been obtained in the computation of cell parameters in the energy range from fission to thermalization through the 238 U resonance region. (U.S.)
Strong Josephson Coupling in Planar Graphene Junctions
Park, Jinho; Lee, Gil-Ho; Lee, Jae Hyeong; Takane, Yositake; Imura, Ken-Ichiro; Taniguchi, Takashi; Watanabe, Kenji; Lee, Hu-Jong
A recent breakthrough of processing graphene, employing encapsulation by hexagonal boron nitride layers (BGB structure), allows realizing the ballistic carrier transport in graphene. Thereafter, ballistic Josephson coupling has been studied by closely edge-contacted BGB structure with two superconducting electrodes. Here, we report on the strong Josephson coupling with planar graphene junction in truly short and ballistic regime. Our device showed high transmission probability and the junction critical current (IC) oscillating for sweeping the gate voltage along with the normal conductance oscillation (Fabry-Perot oscillations), providing a direct evidence for the ballistic nature of the junction pair current. We also observed the convex-upward shape of decreasing critical currents with increasing temperature, canonical properties of the short Josephson coupling. By fitting these curves into theoretical models, we demonstrate the strong Josephson coupling in our devices, which is also supported by the exceptionally large value of ICRN ( 2 Δ / e RNis the normal resistance).
The square of a planar cubic graph is 7-colorable
DEFF Research Database (Denmark)
Thomassen, Carsten
2017-01-01
We prove the conjecture made by G. Wegner in 1977 that the square of every planar, cubic graph is 7-colorable. Here, 7 cannot be replaced by 6.......We prove the conjecture made by G. Wegner in 1977 that the square of every planar, cubic graph is 7-colorable. Here, 7 cannot be replaced by 6....
An efficient planar inverse acoustic method based on Toeplitz matrices
Wind, Jelmer; de Boer, Andries; Ellenbroek, Marcellinus Hermannus Maria
2011-01-01
This article proposes a new, fast method to solve inverse acoustic problems for planar sources. This problem is often encountered in practice and methods such as planar nearfield acoustic holography (PNAH) and statistically optimised nearfield acoustic holography (SONAH) are widely used to solve it.
Array of planar waveguide lasers with 50 GHz frequency spacing
DEFF Research Database (Denmark)
Guldberg-Kjær, Søren Andreas; Laurent-Lund, Christian; Sckerl, Mads W.
1999-01-01
Waveguide laser arrays are demonstrated using planar silica-on-silicon technology. Excellent control over frequency separation is obtained with a single phase mask.......Waveguide laser arrays are demonstrated using planar silica-on-silicon technology. Excellent control over frequency separation is obtained with a single phase mask....
Optically amplifying planar glass waveguides: Laser on a chip
DEFF Research Database (Denmark)
Guldberg-Kjær, Søren Andreas
The objective of this work was to devlop optically amplifying planar wavguides, using erbium-doped germano-silicate glass films deposited by PECVD (Plasma Enhanced Chemical Vapour Deposition). The waveguides should exhibit enough gain to be useful as optical amplifiers in integrated planar lightw...
Mobilities and dislocation energies of planar faults in an ordered ...
Indian Academy of Sciences (India)
Present work describes the stability of possible planar faults of the A3B (D019) phase with an axial ratio less than the ideal. Mobilities and dislocation energies of various planar faults viz. antiphase boundaries (APBs), superlattice intrinsic stacking faults (SISFs) and complex stacking faults (CSFs) have been computed using ...
Column Planarity and Partially-Simultaneous Geometric Embedding
Czech Academy of Sciences Publication Activity Database
Barba, L.; Evans, W.; Hoffmann, M.; Kusters, V.; Saumell, Maria; Speckmann, B.
2017-01-01
Roč. 21, č. 6 (2017), s. 983-1002 ISSN 1526-1719 Grant - others:GA MŠk(CZ) LO1506; GA MŠk(CZ) EE2.3.30.0038 Institutional support: RVO:67985807 Keywords : column planarity * unlabeled level planarity * simultaneous geometric embedding Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics
Panel and planar experimental shear behavior of wood panels ...
African Journals Online (AJOL)
Panel and planar experimental shear behavior of wood panels laminated softwood oriented OSB conditioned at different environments. ... to that measured in the case of panel shear for different environments. Keywords : oriented strand board – panel shear strength- planar shear strength - environment – moisture content ...
Polymer planar Bragg grating for sensing applications
Rosenberger, M.; Hartlaub, N.; Koller, G.; Belle, S.; Schmauss, B.; Hellmann, R.
2013-05-01
Bragg gratings have become indispensable as optical sensing elements and are already used for a variety of technical applications. Mainly silica fiber Bragg gratings (FBGs) have been extensively studied over the last decades and are nowadays commercially available. Bragg grating sensors consisting of other materials like polymers, however, have only recently come into the focus of fundamental and applied research. Polymers exhibit significantly different properties advantageous for many sensing applications and therefore provide a good alternative to silica based devices. In addition, polymer materials are inexpensive, simple to handle as well as available in various forms like liquid resists or bulk material. Accordingly, polymer integrated optics attract increasing interest and can serve as a substitute for optical fibers. We report on the fabrication of a planar Bragg grating sensor in bulk Polymethylmethacrylate (PMMA). The sensor consists of an optical waveguide and a Bragg grating, both written simultaneously into a PMMA chip by a single writing step, for which a phase mask covered by an amplitude mask is placed on top of the PMMA and exposed to the UV radiation of a KrF excimer laser. Depending on the phase mask period, different Bragg gratings reflecting in the telecommunication wavelength range are fabricated and characterized. Reflection and transmission measurements show a narrow reflection band and a high reflectivity of the polymer planar Bragg grating (PPBG). After connecting to a single mode fiber, the portable PPBG based sensor was evaluated for different measurands like humidity and strain. The sensor performance was compared to already existing sensing systems. Due to the obtained results as well as the rapid and cheap fabrication of the sensor chip, the PPBG qualifies for a low cost sensing element.
Nanopatterning planar and non-planar mold surfaces for a polymer replication
DEFF Research Database (Denmark)
Cech, Jiri; Pranov, Henrik; Kofod, Guggi
2013-01-01
We present a novel process to create nanopatterns on planar and non-planar polymer replication tools, such as metallic molds for an injection molding. Such tools with nanopatterned cavities then allow affordable mass production of nanopatterned polymer parts with inherent advanced functionalities...... such as low reflectivity or color effects, self cleaning, superhydrofobicity, antifouling, etc, all created in a single injection molding cycle. Presented process is based on the classic cleanroom microfabrication of micro/nano patterns, nickel electroplating and template removal to form a flexible......, freestanding nickel foil with a reversed pattern. This foil is then used either as a direct master for polymer replication or as a master for an extremely high pressure embossing of such master onto a metallic injection mold cavity surface coated with special coating, which, when cured, forms robust and hard...
On Longest Cycles in Essentially 4-Connected Planar Graphs
Directory of Open Access Journals (Sweden)
Fabrici Igor
2016-08-01
Full Text Available A planar 3-connected graph G is essentially 4-connected if, for any 3-separator S of G, one component of the graph obtained from G by removing S is a single vertex. Jackson and Wormald proved that an essentially 4-connected planar graph on n vertices contains a cycle C such that . For a cubic essentially 4-connected planar graph G, Grünbaum with Malkevitch, and Zhang showed that G has a cycle on at least ¾ n vertices. In the present paper the result of Jackson and Wormald is improved. Moreover, new lower bounds on the length of a longest cycle of G are presented if G is an essentially 4-connected planar graph of maximum degree 4 or G is an essentially 4-connected maximal planar graph.
Morphing Planar Graph Drawings with a Polynomial Number of Steps
DEFF Research Database (Denmark)
Alamdari, Soroush; Angelini, Patrizio; Chan, Timothy M.
2013-01-01
In 1944, Cairns proved the following theorem: given any two straight-line planar drawings of a triangulation with the same outer face, there exists a morph (i.e., a continuous transformation) between the two drawings so that the drawing remains straight-line planar at all times. Cairns’s original...... proof required exponentially many morphing steps. We prove that there is a morph that consists of O(n^2) steps, where each step is a linear morph that moves each vertex at constant speed along a straight line. Using a known result on compatible triangulations this implies that for a general planar graph...... G and any two straight-line planar drawings of G with the same embedding, there is a morph between the two drawings that preserves straight-line planarity and consists of O(n^4) steps....
Ambient mass spectrometry: From the planar to the non-planar surface analysis
Czech Academy of Sciences Publication Activity Database
Rejšek, Jan; Vrkoslav, Vladimír; Cvačka, Josef
2017-01-01
Roč. 15, č. 1 (2017), s. 31 ISSN 2336-7202. [Mezioborové setkání mladých biologů, biochemiků a chemiků /17./. 30.05.2017-01.06.2017, Milovy] Institutional support: RVO:61388963 Keywords : ambient mass spectrometry * thin layer chromatography * non-planar surface analysis Subject RIV: CB - Analytical Chemistry, Separation
Directory of Open Access Journals (Sweden)
J. B. DUMITRU
2014-04-01
Full Text Available This paper presents mathematical modeling and numerical simulation results for a miniature, planar, spiral transformer (MPST fabricated in micro-electromechanical MEMS technology. When the MPST is magnetic nanofluid cored, magnetization body forces occur, entraining it into a complex flow. This particular MPST design is then compared with other competing solutions concerning the lumped (circuit parameters. Finally, the heat transfer problem is solved for different electromagnetic working conditions to assess the thermal loads inside the MPST.
Full Text Available ... and Craniofacial Surgery Cleft Lip/Palate and Craniofacial Surgery A cleft lip may require one or more ... find out more. Corrective Jaw Surgery Corrective Jaw Surgery Orthognathic surgery is performed to correct the misalignment ...
Energy Technology Data Exchange (ETDEWEB)
Zimmermann, Brian E. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Grosev, Darko [Univ. Hospital Centre Zagreb (Croatia); Buvat, Irene [Service Hospitalier Frederic Joliot, Paris (France); and others
2017-08-01
Accurate quantitation of activity provides the basis for internal dosimetry of targeted radionuclide therapies. This study investigated quantitative imaging capabilities at sites with a variety of experience and equipment and assessed levels of errors in activity quantitation in Single-Photon Emission Computed Tomography (SPECT) and planar imaging. Participants from 9 countries took part in a comparison in which planar, SPECT and SPECT with X ray computed tomography (SPECT-CT) imaging were used to quantify activities of four epoxy-filled cylinders containing {sup 133}Ba, which was chosen as a surrogate for {sup 131}I. The sources, with nominal volumes of 2, 4, 6 and 23 mL, were calibrated for {sup 133}Ba activity by the National Institute of Standards and Technology, but the activity was initially unknown to the participants. Imaging was performed in a cylindrical phantom filled with water. Two trials were carried out in which the participants first estimated the activities using their local standard protocols, and then repeated the measurements using a standardized acquisition and analysis protocol. Finally, processing of the imaging data from the second trial was repeated by a single centre using a fixed protocol. In the first trial, the activities were underestimated by about 15% with planar imaging. SPECT with Chang's first order attenuation correction (Chang-AC) and SPECT-CT overestimated the activity by about 10%. The second trial showed moderate improvements in accuracy and variability. Planar imaging was subject to methodological errors, e.g., in the use of a transmission scan for attenuation correction. The use of Chang-AC was subject to variability from the definition of phantom contours. The project demonstrated the need for training and standardized protocols to achieve good levels of quantitative accuracy and precision in a multicentre setting. Absolute quantification of simple objects with no background was possible with the strictest protocol to
Higher-order perturbative corrections to b --> c transitions at zero recoil
Neubert, M
1995-01-01
We estimate the two-loop perturbative corrections to zero-recoil matrix elements of the flavour-changing currents \\bar c\\,\\gamma^\\mu b and \\bar c\\,\\gamma^\\mu\\gamma_5\\,b by calculating the terms of order n_f\\,\\alpha_s^2 and substituting the dependence on the number of flavours by the first coefficient of the \\beta-function. Both for vector and axial vector currents, we find moderate two-loop corrections below 1\\% in magnitude. Using the Brodsky--Lepage--Mack enzie prescription to set the scale in the order-\\alpha_s corrections in the \\overline{\\rm MS} scheme, we obtain \\mu_V\\simeq 0.92\\sqrt{m_b m_c} and \\mu_A\\simeq 0.51\\sqrt{m_b m_c} in the two cases. These scales are sufficiently large for perturbation theory to be well-behaved. The implications of our results to the extraction of |\\, V_{cb}| are briefly discussed.
Computational Study on a PTAS for Planar Dominating Set Problem
Directory of Open Access Journals (Sweden)
Qian-Ping Gu
2013-01-01
Full Text Available The dominating set problem is a core NP-hard problem in combinatorial optimization and graph theory, and has many important applications. Baker [JACM 41,1994] introduces a k-outer planar graph decomposition-based framework for designing polynomial time approximation scheme (PTAS for a class of NP-hard problems in planar graphs. It is mentioned that the framework can be applied to obtain an O(2ckn time, c is a constant, (1+1/k-approximation algorithm for the planar dominating set problem. We show that the approximation ratio achieved by the mentioned application of the framework is not bounded by any constant for the planar dominating set problem. We modify the application of the framework to give a PTAS for the planar dominating set problem. With k-outer planar graph decompositions, the modified PTAS has an approximation ratio (1 + 2/k. Using 2k-outer planar graph decompositions, the modified PTAS achieves the approximation ratio (1+1/k in O(22ckn time. We report a computational study on the modified PTAS. Our results show that the modified PTAS is practical.
Pulsed laser planarization of metal films for multilevel interconnects
International Nuclear Information System (INIS)
Tuckerman, D.B.; Schmitt, R.L.
1985-05-01
Multilevel interconnect schemes for integrated circuits generally require one or more planarization steps, in order to maintain an acceptably flat topography for lithography and thin-film step coverage on the higher levels. Traditional approaches have involved planarization of the interlevel insulation (dielectric) layers, either by spin-on application (e.g., polyimide), or by reflow (e.g., phosphosilicate glass). We have pursued an alternative approach, in which each metal level is melted (hence planarized) using a pulsed laser prior to patterning. Short (approx.1 μs) pulses are used to preclude undesirable metallurgical reactions between the film, adhesion or barrier layer, and dielectric layer. Laser planarization of metals is particularly well suited to multilevel systems which include ground or power planes. Results are presented for planarization of gold films on SiO 2 dielectric layers using a flashlamp-pumped dye laser. The pulse duration is approx.1 μs, which allows the heat pulse to uniformly penetrate the gold while not penetrating substantially through the underlying SiO 2 (hence not perturbing the lower levels of metal). Excellent planarization of the gold films is achieved (less than 0.1 μm surface roughness, even starting with extreme topographic variations), as well as improved conductivity. To demonstrate the process, numerous planarized two-layer structures (transmission lines under a ground plane) were fabricated and characterized. 9 refs., 2 figs
Electrolytic Cell For Production Of Aluminum Employing Planar Anodes.
Energy Technology Data Exchange (ETDEWEB)
Barnett, Robert J. (Goldendale, WA); Mezner, Michael B. (Sandy, OR); Bradford, Donald R (Underwood, WA)
2004-10-05
A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising providing a molten salt electrolyte having alumina dissolved therein in an electrolytic cell. A plurality of anodes and cathodes having planar surfaces are disposed in a generally vertical orientation in the electrolyte, the anodes and cathodes arranged in alternating or interleaving relationship to provide anode planar surfaces disposed opposite cathode planar surfaces, the anode comprised of carbon. Electric current is passed through anodes and through the electrolyte to the cathodes depositing aluminum at the cathodes and forming carbon containing gas at the anodes.
Planar screening by charge polydisperse counterions
Trulsson, M.; Trizac, E.; Šamaj, L.
2018-01-01
We study how a neutralising cloud of counterions screens the electric field of a uniformly charged planar membrane (plate), when the counterions are characterised by a distribution of charges (or valence), n(q) . We work out analytically the one-plate and two-plate cases, at the level of non-linear Poisson–Boltzmann theory. The (essentially asymptotic) predictions are successfully compared to numerical solutions of the full Poisson–Boltzmann theory, but also to Monte Carlo simulations. The counterions with smallest valence control the long-distance features of interactions, and may qualitatively change the results pertaining to the classic monodisperse case where all counterions have the same charge. Emphasis is put on continuous distributions n(q) , for which new power-laws can be evidenced, be it for the ionic density or the pressure, in the one- and two-plates situations respectively. We show that for discrete distributions, more relevant for experiments, these scaling laws persist in an intermediate but yet observable range. Furthermore, it appears that from a practical point of view, hallmarks of the continuous n(q) behaviour are already featured by discrete mixtures with a relatively small number of constituents.
Planar optical waveguide sensor of ammonia
Sarkisov, Sergey S.; Curley, Michael J.; Boykin, Courtney; Diggs, Darnell E.; Grote, James G.; Hopkins, Frank K.
2004-12-01
We describe a novel sensor of ammonia based on a planar optical waveguide made of a thin film of polymer polyimide doped with indicator dye bromocresol purple. The film of dye-doped polyimide demonstrated reversible increase of absorption with a peak near 600 nm in response to presence of ammonia in ambient air. Coupling of input and output optic fibers with the waveguide was done by means of coupling prisms or coupling grooves. The latter configuration has the advantage of low cost, less sensitivity to temperature variation, and the possibility of coupling from both sides of the waveguide. Special experimental setup was built to test the sensor. It included test gas chamber with sealed optic fiber feed-throughs, gas filling line, laser source, photodetector, and signal processing hardware and software. The sensor was capable of detecting 100 ppm of ammonia in air within 8 seconds. Further increase of sensitivity can be achieved by adding more dye dopant to the polymer, increase of the length of the waveguide, and suppression of noise. Overexposure of the sensor to more than 5000 ppm of ammonia led to the saturation of the polymer film and, as a result, significant decrease of sensitivity and increase of the response time. The sensor can be used as low cost component of a distributed optical network of chemical sensors for monitoring presence of hazardous industrial pollutants in air.
Measuring humidity with planar polyimide light guides.
Franke, H; Wagner, D; Kleckers, T; Reuter, R; Rohitkumar, H V; Blech, B A
1993-06-01
Planar polyimide light guides can be used for optical detection of humidity. In a phase-matched guide a TE mode and a TM mode of different orders are influenced differently by a humid atmosphere. With crossed polarizers a phase shift induced by the moisture is detectable in the form of an oscillating output signal. For fully cured and thus well-defined and stable fluorinated polyimide light guides a sensitivity curve is presented for the humidity range of 10-75% relative humidity. A special sensitivity is obtained by using a four-layer waveguide arrangement with two layers of polyimide. The shift of the effective mode indices is also measured for each polarization by using a half-integrated interferometer. The results are interpreted in terms of a refractive-index increase that is due to water indiffusion and a swelling process for higher humidities. The measurement in the waveguide interferometer required a moisture-insensitive coating of the reference channel. This was achieved by the use of fluorinated polymers.
Stress measurements of planar dielectric elastomer actuators
International Nuclear Information System (INIS)
Osmani, Bekim; Aeby, Elise A.; Müller, Bert
2016-01-01
Dielectric elastomer actuator (DEA) micro- and nano-structures are referred to artificial muscles because of their specific continuous power and adequate time response. The bending measurement of an asymmetric, planar DEA is described. The asymmetric cantilevers consist of 1 or 5 μm-thin DEAs deposited on polyethylene naphthalate (PEN) substrates 16, 25, 38, or 50 μm thick. The application of a voltage to the DEA electrodes generates an electrostatic pressure in the sandwiched silicone elastomer layer, which causes the underlying PEN substrate to bend. Optical beam deflection enables the detection of the bending angle vs. applied voltage. Bending radii as large as 850 m were reproducibly detected. DEA tests with electric fields of up to 80 V/μm showed limitations in electrode’s conductivity and structure failures. The actuation measurement is essential for the quantitative characterization of nanometer-thin, low-voltage, single- and multi-layer DEAs, as foreseen for artificial sphincters to efficiently treat severe urinary and fecal incontinence.
Stress measurements of planar dielectric elastomer actuators
Energy Technology Data Exchange (ETDEWEB)
Osmani, Bekim; Aeby, Elise A.; Müller, Bert [Biomaterials Science Center, University of Basel, Gewerbestrasse 14, 4123 Allschwil (Switzerland)
2016-05-15
Dielectric elastomer actuator (DEA) micro- and nano-structures are referred to artificial muscles because of their specific continuous power and adequate time response. The bending measurement of an asymmetric, planar DEA is described. The asymmetric cantilevers consist of 1 or 5 μm-thin DEAs deposited on polyethylene naphthalate (PEN) substrates 16, 25, 38, or 50 μm thick. The application of a voltage to the DEA electrodes generates an electrostatic pressure in the sandwiched silicone elastomer layer, which causes the underlying PEN substrate to bend. Optical beam deflection enables the detection of the bending angle vs. applied voltage. Bending radii as large as 850 m were reproducibly detected. DEA tests with electric fields of up to 80 V/μm showed limitations in electrode’s conductivity and structure failures. The actuation measurement is essential for the quantitative characterization of nanometer-thin, low-voltage, single- and multi-layer DEAs, as foreseen for artificial sphincters to efficiently treat severe urinary and fecal incontinence.
Bimodular high temperature planar oxygen gas sensor
Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Puxian; Lei, Yu
2014-08-01
A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO nanoparticles film was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500 °C, 600 °C and 800 °C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors.
Development of cofired type planar SOFC
Energy Technology Data Exchange (ETDEWEB)
Taira, Hiroaki; Sakamoto, Sadaaki; Zhou, Hua-Bing [Murata Manufacturing Co., Ltd., Shiga (Japan)] [and others
1996-12-31
We have developed fabrication process for planar SOFC fabricated with cofired anode/electrolyte/cathode multilayers and interconnects. By cofiring technique for the multilayers, we expect to reduce the thickness of the electrolyte layers, resulting in decrease of innerimpedance, and achieve low production cost. On the other hand, the cofiring technique requires that the sintering temperature, the shrinkage profiles and the thermal expansion characteristics of all component materials should be compatible with the other. It is, therefore, difficult to cofire the multilayers with large area. Using the multilayers with surface area of 150cm{sup 2}, we fabricated the multiple cell stacks. The maximum power of 5x4 multiple cell stack (5 planes of cells in series, 4 cells in parallel in each planes 484cm{sup 2} effective electrode area of each cell planes) was 601W (0.25Wcm{sup -2}, Uf=40%). However, the terminal voltage of the multiple cell stack decreased by the cause of cell cracking, gas leakage and degradation of cofired multilayers. This paper presents the improvements of cofired multilayers, and the performance of multiple cell stacks with the improved multilayers.
Transfer matrix representation for periodic planar media
Parrinello, A.; Ghiringhelli, G. L.
2016-06-01
Sound transmission through infinite planar media characterized by in-plane periodicity is faced by exploiting the free wave propagation on the related unit cells. An appropriate through-thickness transfer matrix, relating a proper set of variables describing the acoustic field at the two external surfaces of the medium, is derived by manipulating the dynamic stiffness matrix related to a finite element model of the unit cell. The adoption of finite element models avoids analytical modeling or the simplification on geometry or materials. The obtained matrix is then used in a transfer matrix method context, making it possible to combine the periodic medium with layers of different nature and to treat both hard-wall and semi-infinite fluid termination conditions. A finite sequence of identical sub-layers through the thickness of the medium can be handled within the transfer matrix method, significantly decreasing the computational burden. Transfer matrices obtained by means of the proposed method are compared with analytical or equivalent models, in terms of sound transmission through barriers of different nature.
Double shell planar experiments on OMEGA
Dodd, E. S.; Merritt, E. C.; Palaniyappan, S.; Montgomery, D. S.; Daughton, W. S.; Schmidt, D. W.; Cardenas, T.; Wilson, D. C.; Loomis, E. N.; Batha, S. H.; Ping, Y.; Smalyuk, V. A.; Amendt, P. A.
2017-10-01
The double shell project is aimed at fielding neutron-producing capsules at the National Ignition Facility (NIF), in which an outer low-Z ablator collides with an inner high-Z shell to compress the fuel. However, understanding these targets experimentally can be challenging when compared with conventional single shell targets. Halfraum-driven planar targets at OMEGA are being used to study physics issues important to double shell implosions outside of a convergent geometry. Both VISAR and radiography through a tube have advantages over imaging through the hohlraum and double-shell capsule at NIF. A number physics issues are being studied with this platform that include 1-d and higher dimensional effects such as defect-driven hydrodynamic instabilities from engineering features. Additionally, the use of novel materials with controlled density gradients require study in easily diagnosed 1-d systems. This work ultimately feeds back into the NIF capsule platform through manufacturing tolerances set using data from OMEGA. Supported under the US DOE by the LANS, LLC under contract DE-AC52-06NA25396. LA-UR-17-25386.
Planar Hall Effect in Magnetic Conducting Oxides
Akouala, Christer Rajiv
Magnetic semiconductors are of interest for use in non-volatile memory device read heads, magnetoresistive sensors, and other spintronic devices. Research in this area has mostly focused on generating magnetic semiconductors by doping non-magnetic semiconductors with magnetic ions. This work has instead taken advantage of the defectinduced magnetism in several semiconducting oxides. The planar Hall effect (PHE) is a phenomenon that can be used for characterizing magnetic semiconductors. Along with the anisotropic magnetoresistance (AMR), PHE has the potential to provide insight into the mechanism for magnetic behavior in magnetic conducting oxide thin films that are undoped. PHE has therefore been studied in undoped ZnO, SnO2, CdO, and CuO using magnetotransport and magnetometry techniques. The measurements included both AMR and PHE taken at various temperatures from 300 to 4.2K in a Quantum Design Physical Property Measurement System (QD-PPMS) and in a custom-built magnetotransport set-up. Complementary measurements include XRD, and resistivity measurements. Resistivity vs. temperature, Hall effect, and magnetoresistance measurements were performed in the PPMS. Magnetic hysteresis and magnetization vs. temperature were acquired using a Quantum Design Magnetic Properties Measurement System (QD-MPMS).
Lane detection using road planar information
He, Qiang; Chu, Chee-Hung H.
2011-06-01
Intelligent vehicles have many applications in the military, aerospace, and other industries, including land-mine detection for the military, patient transportation in hospitals, and many other domains that often require automation to reduce risks to the human operators. One of important tasks of intelligent vehicles is the navigation, whose goal is to extract and determine the appropriate path that leads to a destination based on perceived environmental information. The objective of our work is to develop a simple and effective method to detect and extract road lanes and boundaries. We propose a solution by incorporating the planar information of road surfaces. We first detect all possible edges in the captured images. The straight lanes and boundaries are extracted as straight lines, which generate a vanishing point. The straight lines are described with Hough transform. A cluster analysis in Hough space is used to detect the vanishing point on road. Further, we search lines passing through the vanishing point from 180 degrees to 270 degrees and from 0 degree to negative 90 degrees. The first two strong lines will be extracted as road boundaries.
Bimodular high temperature planar oxygen gas sensor
Directory of Open Access Journals (Sweden)
Xiangcheng eSun
2014-08-01
Full Text Available A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs thin film coated yttria-stabilized zirconia (YSZ substrate. The thin film was prepared by radio frequency (r.f. magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO nanoparticles film was characterized by atomic force microscopy (AFM and scanning electron microscopy (SEM. X-ray diffraction (XRD patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500 °C, 600 °C and 800 °C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors.
Analytical response function for planar Ge detectors
García-Alvarez, Juan A.; Maidana, Nora L.; Vanin, Vito R.; Fernández-Varea, José M.
2016-04-01
We model the response function (RF) of planar HPGe x-ray spectrometers for photon energies between around 10 keV and 100 keV. The RF is based on the proposal of Seltzer [1981. Nucl. Instrum. Methods 188, 133-151] and takes into account the full-energy absorption in the Ge active volume, the escape of Ge Kα and Kβ x-rays and the escape of photons after one Compton interaction. The relativistic impulse approximation is employed instead of the Klein-Nishina formula to describe incoherent photon scattering in the Ge crystal. We also incorporate a simple model for the continuous component of the spectrum produced by the escape of photo-electrons from the active volume. In our calculations we include external interaction contributions to the RF: (i) the incoherent scattering effects caused by the detector's Be window and (ii) the spectrum produced by photo-electrons emitted in the Ge dead layer that reach the active volume. The analytical RF model is compared with pulse-height spectra simulated using the PENELOPE Monte Carlo code.
Planar high temperature superconductor filters with backside coupling
Shen, Zhi-Yuan (Inventor)
1998-01-01
An improved high temperature superconducting planar filter wherein the coupling circuit or connecting network is located, in whole or in part, on the side of the substrate opposite the resonators and enables higher power handling capability.
Photoacoustic imaging using acoustic reflectors to enhance planar arrays.
Ellwood, Robert; Zhang, Edward; Beard, Paul; Cox, Ben
2014-12-01
Planar sensor arrays have advantages when used for photoacoustic imaging: they do not require the imaging target to be enclosed, and they are easier to manufacture than curved arrays. However, planar arrays have a limited view of the acoustic field due to their finite size; therefore, not all of the acoustic waves emitted from a photoacoustic source can be recorded. This loss of data results in artifacts in the reconstructed photoacoustic image. A detection array configuration which combines a planar Fabry–Pérot sensor with perpendicular acoustic reflectors is described and experimentally implemented. This retains the detection advantages of the planar sensor while increasing the effective detection aperture in order to improve the reconstructed photoacoustic image.
Principles of planar near-field antenna measurements
Gregson, Stuart; Parini, Clive
2007-01-01
This single volume provides a comprehensive introduction and explanation of both the theory and practice of 'Planar Near-Field Antenna Measurement' from its basic postulates and assumptions, to the intricacies of its deployment in complex and demanding measurement scenarios.
Controlling the quantum rotational dynamics of a driven planar rotor ...
Indian Academy of Sciences (India)
Archana Shukla
driven planar rotor, a model for rigid diatomic molecules, by rebuilding barriers in the classical phase space. The barriers are invariant tori with irrational winding ratios which are perturbatively constructed at desired locations in the phase space. We.
Mobilities and dislocation energies of planar faults in an ordered ...
Indian Academy of Sciences (India)
D019) phase with an axial ratio less than the ideal. Mobilities and dislocation energies of various planar faults viz. antiphase boundaries (APBs), superlattice intrinsic stacking faults (SISFs) and complex stacking faults (CSFs) have been ...
On the maximum number of cycles in a planar graph
DEFF Research Database (Denmark)
Aldred, R.E.L.; Thomassen, Carsten
2008-01-01
Let G be a graph on p vertices with q edges and let r = q - p + 1. We show that G has at most 15/162(r) cycles. We also show that if G is planar, then G has at most 2(r-1) + o(2(r-1)) cycles. The planar result is best possible in the sense that any prism, that is, the Cartesian product of a cycle...
Planar chiral meta-materials for optical applications
Potts, A.; Papakostas, A.; Bagnall, D. M.; Zheludev, N. I.
2004-01-01
Room temperature nanoimprint lithography has successfully been applied to the fabrication of planar chiral photonic meta-materials. For dielectric chiral structures a single layer of thick HSQ was used while for metallic chiral structures a bi-layer technique using PMMA/hydrogen silsequioxane (HSQ) was applied. The polarization conversion capabilities of planar chiral structures imprinted in dielectric materials have experimentally been observed. This indicates that the developed processes in...
Surfaces foliated by planar geodesics: a model forcurved wood design
DEFF Research Database (Denmark)
Brander, David; Gravesen, Jens
2017-01-01
Surfaces foliated by planar geodesics are a natural model for surfaces made from wood strips. We outline how to construct all solutions, and produce non-trivial examples, such as a wood-strip Klein bottle......Surfaces foliated by planar geodesics are a natural model for surfaces made from wood strips. We outline how to construct all solutions, and produce non-trivial examples, such as a wood-strip Klein bottle...
Group theoretical construction of planar noncommutative phase spaces
Energy Technology Data Exchange (ETDEWEB)
Ngendakumana, Ancille, E-mail: nancille@yahoo.fr; Todjihoundé, Leonard, E-mail: leonardt@imsp.uac.org [Institut de Mathématiques et des Sciences Physiques (IMSP), Porto-Novo (Benin); Nzotungicimpaye, Joachim, E-mail: kimpaye@kie.ac.rw [Kigali Institute of Education (KIE), Kigali (Rwanda)
2014-01-15
Noncommutative phase spaces are generated and classified in the framework of centrally extended anisotropic planar kinematical Lie groups as well as in the framework of noncentrally abelian extended planar absolute time Lie groups. Through these constructions the coordinates of the phase spaces do not commute due to the presence of naturally introduced fields giving rise to minimal couplings. By symplectic realizations methods, physical interpretations of generators coming from the obtained structures are given.
$1$-string $B_2$-VPG representation of planar graphs
Directory of Open Access Journals (Sweden)
Therese Biedl
2016-09-01
Full Text Available In this paper, we prove that every planar graph has a 1-string $B_2$-VPG representation—a string representation using paths in a rectangular grid that contain at most two bends. Furthermore, two paths representing vertices $u,v$ intersect precisely once whenever there is an edge between $u$ and $v$. We also show that only a subset of the possible curve shapes is necessary to represent $4$-connected planar graphs.
Retracing the path of planar cell polarity.
Schenkelaars, Quentin; Fierro-Constain, Laura; Renard, Emmanuelle; Borchiellini, Carole
2016-04-02
The Planar Cell Polarity pathway (PCP) has been described as the main feature involved in patterning cell orientation in bilaterian tissues. Recently, a similar phenomenon was revealed in cnidarians, in which the inhibition of this pathway results in the absence of cilia orientation in larvae, consequently proving the functional conservation of PCP signaling between Cnidaria and Bilateria. Nevertheless, despite the growing accumulation of databases concerning basal lineages of metazoans, very few information concerning the existence of PCP components have been gathered outside of Bilateria and Cnidaria. Thus, the origin of this module or its prevalence in early emerging metazoans has yet to be elucidated. The present study addresses this question by investigating the genomes and transcriptomes from all poriferan lineages in addition to Trichoplax (Placozoa) and Mnemiopsis (Ctenophora) genomes for the presence of the core components of this pathway. Our results confirm that several PCP components are metazoan innovations. In addition, we show that all members of the PCP pathway, including a bona fide Strabismus ortholog (Van gogh), are retrieved only in one sponge lineage (Homoscleromorpha) out of four. This highly suggests that the full PCP pathway dates back at least to the emergence of homoscleromorph sponges. Consequently, several secondary gene losses would have occurred in the three other poriferan lineages including Amphimedon queenslandica (Demospongiae). Several proteins were not retrieved either in placozoans or ctenophores leading us to discuss the difficulties to predict orthologous proteins in basally branching animals. Finally, we reveal how the study of multigene families may be helpful to unravel the relationships at the base of the metazoan tree. The PCP pathway antedates the radiation of Porifera and may have arisen in the last common ancestor of animals. Oscarella species now appear as key organisms to understand the ancestral function of PCP
Delivering both sum and difference beam distributions to a planar monopulse antenna array
Strassner, II, Bernd H.
2015-12-22
A planar monopulse radar apparatus includes a planar distribution matrix coupled to a planar antenna array having a linear configuration of antenna elements. The planar distribution matrix is responsive to first and second pluralities of weights applied thereto for providing both sum and difference beam distributions across the antenna array.
Quality control on planar n-in-n pixel sensors — Recent progress of ATLAS planar pixel sensors
International Nuclear Information System (INIS)
Klingenberg, R.
2013-01-01
To extend the physics reach of the Large Hadron Collider (LHC), upgrades to the accelerator are planned which will increase the peak luminosity by a factor 5–10. To cope with the increased occupancy and radiation damage, the ATLAS experiment plans to introduce an all-silicon inner tracker with the high luminosity upgrade (HL-LHC). To investigate the suitability of pixel sensors using the proven planar technology for the upgraded tracker, the ATLAS Upgrade Planar Pixel Sensor (PPS) R and D Project was established. Main areas of research are the performance of planar pixel sensors at highest fluences, the exploration of possibilities for cost reduction to enable the instrumentation of large areas, the achievement of slim or active edges to provide low geometric inefficiencies without the need for shingling of modules and the investigation of the operation of highly irradiated sensors at low thresholds to increase the efficiency. The Insertable b-layer (IBL) is the first upgrade project within the ATLAS experiment and will employ a new detector layer consisting of silicon pixel sensors, which were improved and prototyped in the framework of the planar pixel sensor R and D project. A special focus of this paper is the status of the development and testing of planar n-in-n pixel sensors including the quality control of the on-going series production and postprocessing of sensor wafers. A high yield of produced planar sensor wafers and FE-I4 double chip sensors after first steps of post-processing including under bump metallization and dicing is observed. -- Highlights: ► Prototypes of irradiated planar n-in-n sensors have been successfully tested under laboratory conditions. ► A quality assurance programme on the series production of planar sensors for the IBL has started. ► A high yield of double chip sensors during the series production is observed which are compatible to the specifications to this detector component.
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NWS Corrections to Observations
National Oceanic and Atmospheric Administration, Department of Commerce — Form B-14 is the National Weather Service form entitled 'Notice of Corrections to Weather Records.' The forms are used to make corrections to observations on forms...
Teaching Politically Correct Language
Tsehelska, Maryna
2006-01-01
This article argues that teaching politically correct language to English learners provides them with important information and opportunities to be exposed to cultural issues. The author offers a brief review of how political correctness became an issue and how being politically correct influences the use of language. The article then presents…
WIP: A Web-based program for indexing planar features in quartz grains and its usage
Losiak, Anna; Golebiowska, Izabela; FerrièRe, Ludovic; Wojciechowski, Jacek; Huber, Matthew S.; Koeberl, Christian
2016-04-01
Planar deformation features (PDFs) in quartz are the most important diagnostic features that allow the unambiguous identification of impact structures on Earth. In order to confirm that these features (that are characterized by planar character and form along specific crystallographic planes) are indeed PDFs, they need to be properly investigated and indexed. Following universal-stage measurements, the process of indexing is usually performed manually, using a Wulff stereonet and following a strict procedure, which is time consuming and error prone. In this article, we present WIP, a new Web-based program for indexing planar deformation features in quartz. The correctness of our program is shown by its application to measurements that had previously been indexed manually. The observed minor differences, especially in the absolute frequency percentage of PDFs, are negligible and not significant enough to influence the estimation of shock pressure that could be calculated from the indexed results. Usability of this program is shown using the spatial relationships between a statistically significant number of 278 quartz grains with 409 sets of PDFs analyzed within the area ( 35 mm2) of a single thin section of a meta-greywacke from the Bosumtwi impact structure. Our program is not only more accurate and faster than the manual (graphical) method but also removes the human error from the plotting process and allows control of several parameters, such as the value of estimated measurement error used in the indexing calculation or method of aggregated error handling. The program also provides information about the angles between the planes of the measured PDF sets present in a grain, which allows determination of the angles between (for example) indexed {10accent="true">1¯3} and {10accent="true">1¯1} sets.
Anions, quantum particles in planar systems; Anions, particulas quanticas em sistemas planares
Energy Technology Data Exchange (ETDEWEB)
Monerat, Germano Amaral [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Fisica]. E-mail: monerat@if.uff.br
2000-03-01
Our purpose here is to present a general review of the non-relativistic quantum-mechanical description of excitations that do not obey neither the Fermi-Dirac nor the Bose-Einstein statistics; they rather fulfill an intermediate statistics, the we called 'any-statistics'. As we shall see, this is a peculiarity of (1+1) and (1+2) dimensions, due to the fact that, in two space dimensions, the spin is not quantised, once the rotation group is Abelian. The relevance of studying theories in (1+2) dimensions is justified by the evidence that, in condensed matter physics, there are examples of planar systems, for which everything goes as if the third spatial dimension is frozen. (author)
Belief propagation and loop series on planar graphs
International Nuclear Information System (INIS)
Chertkov, Michael; Teodorescu, Razvan; Chernyak, Vladimir Y
2008-01-01
We discuss a generic model of Bayesian inference with binary variables defined on edges of a planar graph. The Loop Calculus approach of Chertkov and Chernyak (2006 Phys. Rev. E 73 065102(R) [cond-mat/0601487]; 2006 J. Stat. Mech. P06009 [cond-mat/0603189]) is used to evaluate the resulting series expansion for the partition function. We show that, for planar graphs, truncating the series at single-connected loops reduces, via a map reminiscent of the Fisher transformation (Fisher 1961 Phys. Rev. 124 1664), to evaluating the partition function of the dimer-matching model on an auxiliary planar graph. Thus, the truncated series can be easily re-summed, using the Pfaffian formula of Kasteleyn (1961 Physics 27 1209). This allows us to identify a big class of computationally tractable planar models reducible to a dimer model via the Belief Propagation (gauge) transformation. The Pfaffian representation can also be extended to the full Loop Series, in which case the expansion becomes a sum of Pfaffian contributions, each associated with dimer matchings on an extension to a subgraph of the original graph. Algorithmic consequences of the Pfaffian representation, as well as relations to quantum and non-planar models, are discussed
A generalized Beraha conjecture for non-planar graphs
Energy Technology Data Exchange (ETDEWEB)
Jacobsen, Jesper Lykke, E-mail: jesper.jacobsen@ens.fr [Laboratoire de Physique Théorique, École Normale Supérieure, 24 rue Lhomond, 75231 Paris (France); Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris (France); Salas, Jesús, E-mail: jsalas@math.uc3m.es [Grupo de Modelización, Simulación Numérica y Matemática Industrial, Universidad Carlos III de Madrid, Avda. de la Universidad, 30, 28911 Leganés (Spain); Grupo de Teorías de Campos y Física Estadística, Instituto Gregorio Millán, Universidad Carlos III de Madrid, Unidad Asociada al IEM–CSIC, Madrid (Spain)
2013-10-21
We study the partition function Z{sub G(nk,k)}(Q,v) of the Q-state Potts model on the family of (non-planar) generalized Petersen graphs G(nk,k). We study its zeros in the plane (Q,v) for 1⩽k⩽7. We also consider two specializations of Z{sub G(nk,k)}, namely the chromatic polynomial P{sub G(nk,k)}(Q) (corresponding to v=−1), and the flow polynomial Φ{sub G(nk,k)}(Q) (corresponding to v=−Q). In these two cases, we study their zeros in the complex Q-plane for 1⩽k⩽7. We pay special attention to the accumulation loci of the corresponding zeros when n→∞. We observe that the Berker–Kadanoff phase that is present in two-dimensional Potts models, also exists for non-planar recursive graphs. Their qualitative features are the same; but the main difference is that the role played by the Beraha numbers for planar graphs is now played by the non-negative integers for non-planar graphs. At these integer values of Q, there are massive eigenvalue cancellations, in the same way as the eigenvalue cancellations that happen at the Beraha numbers for planar graphs.
Fluorescence based fiber optic and planar waveguide biosensors. A review
Energy Technology Data Exchange (ETDEWEB)
Benito-Peña, Elena [Department of Analytical Chemistry, Faculty of Chemistry, Complutense University, 28040 Madrid (Spain); Valdés, Mayra Granda [Department of Analytical Chemistry, Faculty of Chemistry, University of La Habana, 10400 La Habana (Cuba); Glahn-Martínez, Bettina [Department of Analytical Chemistry, Faculty of Chemistry, Complutense University, 28040 Madrid (Spain); Moreno-Bondi, Maria C., E-mail: mcmbondi@quim.ucm.es [Department of Analytical Chemistry, Faculty of Chemistry, Complutense University, 28040 Madrid (Spain)
2016-11-02
The application of optical biosensors, specifically those that use optical fibers and planar waveguides, has escalated throughout the years in many fields, including environmental analysis, food safety and clinical diagnosis. Fluorescence is, without doubt, the most popular transducer signal used in these devices because of its higher selectivity and sensitivity, but most of all due to its wide versatility. This paper focuses on the working principles and configurations of fluorescence-based fiber optic and planar waveguide biosensors and will review biological recognition elements, sensing schemes, as well as some major and recent applications, published in the last ten years. The main goal is to provide the reader a general overview of a field that requires the joint collaboration of researchers of many different areas, including chemistry, physics, biology, engineering, and material science. - Highlights: • Principles, configurations and fluorescence techniques using fiber optic and planar waveguide biosensors are discussed. • The biorecognition elements and sensing schemes used in fiber optic and planar waveguide platforms are reviewed. • Some major and recent applications of fiber optic and planar waveguide biosensors are introduced.
The Gibbs free energy of homogeneous nucleation: From atomistic nuclei to the planar limit.
Cheng, Bingqing; Tribello, Gareth A; Ceriotti, Michele
2017-09-14
In this paper we discuss how the information contained in atomistic simulations of homogeneous nucleation should be used when fitting the parameters in macroscopic nucleation models. We show how the number of solid and liquid atoms in such simulations can be determined unambiguously by using a Gibbs dividing surface and how the free energy as a function of the number of solid atoms in the nucleus can thus be extracted. We then show that the parameters (the chemical potential, the interfacial free energy, and a Tolman correction) of a model based on classical nucleation theory can be fitted using the information contained in these free-energy profiles but that the parameters in such models are highly correlated. This correlation is unfortunate as it ensures that small errors in the computed free energy surface can give rise to large errors in the extrapolated properties of the fitted model. To resolve this problem we thus propose a method for fitting macroscopic nucleation models that uses simulations of planar interfaces and simulations of three-dimensional nuclei in tandem. We show that when the chemical potentials and the interface energy are pinned to their planar-interface values, more precise estimates for the Tolman length are obtained. Extrapolating the free energy profile obtained from small simulation boxes to larger nuclei is thus more reliable.
Energy Technology Data Exchange (ETDEWEB)
Phillips, J.J., E-mail: jimphillips@nhs.net [Nuclear Medicine, Aberdeen Royal Infirmary, NHS Grampian, Foresterhill Road, Aberdeen AB25 2ZN (United Kingdom); Straiton, J. [Radiology, Aberdeen Royal Infirmary, NHS Grampian, Foresterhill Road, Aberdeen AB25 2ZN (United Kingdom); Staff, R.T. [Nuclear Medicine, Aberdeen Royal Infirmary, NHS Grampian, Foresterhill Road, Aberdeen AB25 2ZN (United Kingdom)
2015-07-15
Diagnosing acute pulmonary embolism (PE) is an indication for scintillation V/Q imaging (planar and SPECT) and/or CTPA. This study reviews, compares and aggregates the published diagnostic performance of each modality and assesses the short-term consequences in terms of diagnostic outcomes, monetary cost, and radiation burden. We performed a formal literature review of available data and aggregated the finding using a summary receiver operating characteristic. A decision tree approach was used to estimate cost and dose per correct diagnosis. The review found 19 studies, which comprised 27 data sets (6393 examinations, from 5923 patients). The results showed that planar V/Q was significantly inferior to both V/Q SPECT and CTPA with no difference between the latter two. CTPA represents best value; £129 per correct diagnosis compared to £243 (SPECT) and £226 (planar). In terms of radiation burden V/Q SPECT was the most effective with a dose of 2.12 mSv per correct diagnosis compared with 3.46 mSv (planar) and 4.96 (CTPA) mSv. These findings show no performance difference between V/Q SPECT and CTPA; planar V/Q is inferior. CTPA is clearly the most cost effective technique. V/Q SPECT should be considered in situations where radiation dose is of concern or CTPA is inappropriate.
Isolated planar gyroscope with internal radial sensing and actuation
Shcheglov, Kirill V. (Inventor); Challoner, A. Dorian (Inventor)
2006-01-01
The present invention discloses an inertial sensor comprising a planar mechanical resonator with embedded sensing and actuation for substantially in-plane vibration and having a central rigid support for the resonator. At least one excitation or torquer electrode is disposed within an interior of the resonator to excite in-plane vibration of the resonator and at least one sensing or pickoff electrode is disposed within the interior of the resonator for sensing the motion of the excited resonator. In one embodiment, the planar resonator includes a plurality of slots in an annular pattern; in another embodiment, the planar mechanical resonator comprises four masses; each embodiment having a simple degenerate pair of in-plane vibration modes.
A constant gradient planar accelerating structure for linac use
International Nuclear Information System (INIS)
Kang, Y.W.; Matthews, P.J.; Kustom, R.L.
1995-01-01
Planar accelerating millimeter-wave structures have been studied during the last few years at Argonne National Laboratory in collaboration with Technical University of Berlin. The cavity structures are intended to be manufactured by using x-ray lithography microfabrication technology. A complete structure consists of two identical planar half structures put together face-to-face. Since microfabrication technology can make a since-depth indentation on a planar substrate, realizing the constant impedance structure was possible but a constant gradient structure was difficult; changing the group velocity along the structure while maintaining the gap and the depth of the indentation constant was difficult. A constant gradient structure has been devised by introducing a cut between the adjacent cavity cells along the beam axis of each half structure. The width of the cut is varied along the longitudinal axis of the structure to have proper coupling between the cells. The result of the computer simulation on such structures is shown
Frontiers in Planar Lightwave Circuit Technology Design, Simulation, and Fabrication
Janz, Siegfried; Tanev, Stoyan
2005-01-01
This book is the result of the NATO Advanced Research Workshop on Frontiers in Planar Lightwave Circuit Technology, which took place in Ottawa, Canada from September 21-25, 2004. Many of the world’s leading experts in integrated photonic design, theory and experiment were invited to give lectures in their fields of expertise, and participate in discussions on current research and applications, as well as the new directions planar lightwave circuit technology is evolving towards. The sum of their contributions to this book constitutes an excellent record of many key issues and scientific problems in planar lightwave circuit research at the time of writing. In this volume the reader will find detailed overviews of experimental and theoretical work in high index contrast waveguide systems, micro-optical resonators, nonlinear optics, and advanced optical simulation methods, as well as articles describing emerging applications of integrated optics for medical and biological applications.
Organic light-emitting diodes from homoleptic square planar complexes
Omary, Mohammad A
2013-11-12
Homoleptic square planar complexes [M(N.LAMBDA.N).sub.2], wherein two identical N.LAMBDA.N bidentate anionic ligands are coordinated to the M(II) metal center, including bidentate square planar complexes of triazolates, possess optical and electrical properties that make them useful for a wide variety of optical and electrical devices and applications. In particular, the complexes are useful for obtaining white or monochromatic organic light-emitting diodes ("OLEDs"). Improved white organic light emitting diode ("WOLED") designs have improved efficacy and/or color stability at high brightness in single- or two-emitter white or monochrome OLEDs that utilize homoleptic square planar complexes, including bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) ("Pt(ptp).sub.2").
Planarization Profile Measurement Using A Confocal Scanning Laser Microscope
Smith, Ian R.; Bennett, Simon D.; Lindow, James T.; Monahan, Kevin
1986-08-01
The use of planarizing layers to improve the performance of photolithography for micron and submicron devices is being actively explored by a number of semiconductor companies. The usefulness of the procedure depends critically upon the degree to which residual surface undulations can be controlled. This paper describes how a confocal scanning optical microscope may be used to measure surface profiles of planarizing layers and discusses the factors which influence the accuracy of measurement. Experimental measurements, using a SiScan-I system, of resist and P.S.G. planarizing layers are presented, demonstrating a sensitivity to surface height changes of 50 nm. The technique may be improved upon by careful design of the microscope and selection of the imaging wavelength. These factors are discussed.
Planar Submillimeter-Wave Mixer Technology with Integrated Antenna
Chattopadhyay, Gautam; Mehdi, Imran; Gill, John J.; Lee, Choonsup; lombart, Muria L.; Thomas, Betrand
2010-01-01
High-performance mixers at terahertz frequencies require good matching between the coupling circuits such as antennas and local oscillators and the diode embedding impedance. With the availability of amplifiers at submillimeter wavelengths and the need to have multi-pixel imagers and cameras, planar mixer architecture is required to have an integrated system. An integrated mixer with planar antenna provides a compact and optimized design at terahertz frequencies. Moreover, it leads to a planar architecture that enables efficient interconnect with submillimeter-wave amplifiers. In this architecture, a planar slot antenna is designed on a thin gallium arsenide (GaAs) membrane in such a way that the beam on either side of the membrane is symmetric and has good beam profile with high coupling efficiency. A coplanar waveguide (CPW) coupled Schottky diode mixer is designed and integrated with the antenna. In this architecture, the local oscillator (LO) is coupled through one side of the antenna and the RF from the other side, without requiring any beam sp litters or diplexers. The intermediate frequency (IF) comes out on a 50-ohm CPW line at the edge of the mixer chip, which can be wire-bonded to external circuits. This unique terahertz mixer has an integrated single planar antenna for coupling both the radio frequency (RF) input and LO injection without any diplexer or beamsplitters. The design utilizes novel planar slot antenna architecture on a 3- mthick GaAs membrane. This work is required to enable future multi-pixel terahertz receivers for astrophysics missions, and lightweight and compact receivers for planetary missions to the outer planets in our solar system. Also, this technology can be used in tera hertz radar imaging applications as well as for testing of quantum cascade lasers (QCLs).
An iterative method for the canard explosion in general planar systems
DEFF Research Database (Denmark)
Brøns, Morten
2012-01-01
The canard explosion is the change of amplitude and period of a limit cycle born in a Hopf bifurcation in a very narrow parameter interval. The phenomenon is well understood in singular perturbation problems where a small parameter controls the slow/fast dynamics. However, canard explosions are a...... equation, showing that the asymptotics of the method is correct, and on a templator model for a self-replicating system....... are also observed in systems where no such parameter is present. Here we show how the iterative method of Roussel and Fraser, devised to construct regular slow manifolds, can be used to determine a canard point in a general planar system of nonlinear ODEs. We demonstrate the method on the van der Pol...
An iterative method for the canard explosion in general planar systems
DEFF Research Database (Denmark)
Brøns, Morten
2013-01-01
The canard explosion is the change of amplitude and period of a limit cycle born in a Hopf bifurcation in a very narrow parameter interval. The phenomenon is well understood in singular perturbation problems where a small parameter controls the slow/fast dynamics. However, canard explosions are a...... on the van der Pol equation, showing that the asymptotics of the method is correct, and on a templator model for a self-replicating system....... are also observed in systems where no such parameter can obviously be identied. Here we show how the iterative method of Roussel and Fraser, devised to construct regular slow manifolds, can be used to determine a canard point in a general planar system of nonlinear ODEs. We demonstrate the method...
Exact spectrum of anomalous dimensions of planar N = 4 supersymmetric Yang-Mills theory.
Gromov, Nikolay; Kazakov, Vladimir; Vieira, Pedro
2009-09-25
We present a set of functional equations defining the anomalous dimensions of arbitrary local single trace operators in planar N = 4 supersymmetric Yang-Mills theory. It takes the form of a Y system based on the integrability of the dual superstring sigma model on the five-dimensional anti-de Sitter space (AdS_{5} x S;{5}) background. This Y system passes some very important tests: it incorporates the full asymptotic Bethe ansatz at large length of operator L, including the dressing factor, and it confirms all recently found wrapping corrections. The recently proposed AdS_{4}/three-dimensional conformal field theory duality is also treated in a similar fashion.
Integrating sphere for solar transmittance measurement of planar and nonplanar samples.
Symons, J G; Christie, E A; Peck, M K
1982-08-01
A new apparatus that incorporates an integrating sphere is described, which enables the solar transmittance of test samples to be measured as a function of both angle of incidence and azimuth angle. This apparatus was developed to perform measurements on both planar and nonplanar samples of larger dimensions than can be accommodated in a spectrophotometer. Solar transmittance measurements from this apparatus are compared with those from a Gier & Dunkle spectrophotometer for a range of sample materials, and excellent agreement has been found. Errors in solar transmittance measurement may arise from changes in the integrating sphere entrance port reflectance due to placement and then the removal of the test sample from the port. A correction procedure is derived to take account of these errors and is applicable to all single-beam integrating spheres.
Planar Josephson tunnel junctions in a transverse magnetic field
DEFF Research Database (Denmark)
Monacoa, R.; Aarøe, Morten; Mygind, Jesper
2007-01-01
Traditionally, since the discovery of the Josephson effect in 1962, the magnetic diffraction pattern of planar Josephson tunnel junctions has been recorded with the field applied in the plane of the junction. Here we discuss the static junction properties in a transverse magnetic field where...... demagnetization effects imposed by the tunnel barrier and electrodes geometry are important. Measurements of the junction critical current versus magnetic field in planar Nb-based high-quality junctions with different geometry, size, and critical current density show that it is advantageous to use a transverse...... magnetic field rather than an in-plane field. The conditions under which this occurs are discussed....
60-dB Bragg gratings in planar waveguides
DEFF Research Database (Denmark)
Jouanno, Jean-Marc; Hübner, Jörg; Kristensen, M.
1997-01-01
Bragg gratings are widely used as wavelength-selective elements in fiber devices. Integrated optics is a very attractive alternative for realizing such components. This way, multifunctional devices with high mechanical and thermal stability can be made using a technology with potential for mass-production....... The main limitation until now was the quality of the gratings written in planar waveguides. We report here 60-dB transmission dips obtained with 6-mm-long Bragg gratings written in Ge-doped planar waveguides...
Design of planar light guide concentrators for building integrated photovoltaics
Fennig, Eryn; Schmidt, Greg; Moore, Duncan T.
2017-11-01
There are advantages to using planar light guide (PLG) concentrators instead of Fresnel concentrators for glass building façade photovoltaic systems. This paper details the main components of a PLG concentrator and describes how the concentrator works. The design of a PLG concentrator is constrained by the limitations of the diamond turning process used to make the microlens array. These manufacturing limitations and their effects on the lens design and system performance are reviewed. We report on the design of a 25 × 100 mm planar light guide concentrator with a 50x geometric concentration and an 85.0-88.1% theoretical optical efficiency for use in building integrated photovoltaics.
Asymmetric transmission of a planar metamaterial induced by symmetry breaking
Bai, Yu; Chen, Yuyan; Zhang, Yongyuan; Wang, Yongkai; Aba, Tudahong; Li, Hui; Wang, Li; Zhang, Zhongyue
2018-03-01
Asymmetric transmission (AT) is widely used in polarization transformers and polarization-controlled devices. In this paper, a planar metamaterial nanostructure with connected gammadion-shaped nanostructure (CGN) is proposed to achieve AT effect for forward and backward propagations of circular polarized light. The CGN arrays can produce magnetic moment oscillation that is normal to the metamaterial plane, which is weakly coupled to free space and generates transmission valleys. The introduction of symmetry breaking exerts a strong influence on the AT effects, and these effects can be tuned by the structural parameters. Our planar metamaterials may have potential for application in the future design of polarization-controlling devices.
Geometrically induced surface polaritons in planar nanostructured metallic cavities
Energy Technology Data Exchange (ETDEWEB)
Davids, P. S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Intravia, F [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalvit, Diego A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-01-14
We examine the modal structure and dispersion of periodically nanostructured planar metallic cavities within the scattering matrix formulation. By nanostructuring a metallic grating in a planar cavity, artificial surface excitations or spoof plasmon modes are induced with dispersion determined by the periodicity and geometric characteristics of the grating. These spoof surface plasmon modes are shown to give rise to new cavity polaritonic modes at short mirror separations that modify the density of modes in nanostructured cavities. The increased modal density of states form cavity polarirons have a large impact on the fluctuation induced electromagnetic forces and enhanced hear transfer at short separations.
Planar Near-Field Measurements of Ground Penetrating Radar Antennas
DEFF Research Database (Denmark)
Meincke, Peter; Hansen, Thorkild
2004-01-01
Planar near-field measurements are formulated for a general ground penetrating radar (GPR) antenna. A total plane-wave scattering matrix is defined for the system consisting of the GPR antenna and the planar air-soil interface. The transmitting spectrum of the GPR antenna is expressed in terms...... of measurements obtained with a buried probe as the GPR antenna moves over a scan plane on the ground. A numerical example in which the scan plane is finite validates the expressions for the spectrum of the GPR antenna....
Electromagnetically Induced Transparency in Symmetric Planar Metamaterial at THz Wavelengths
Directory of Open Access Journals (Sweden)
Abdelwaheb Ourir
2015-03-01
Full Text Available We report the experimental observation and the evidence of the analogue of electromagnetically-induced transparency (EIT in a symmetric planar metamaterial. This effect has been obtained in the THz range thanks to a destructive Fano-interference between the two first modes of an array of multi-gap split ring resonators deposited on a silicon substrate. This structure is a planar thin film material with four-fold symmetry. Thanks to this property, a polarization-independent transmission has been achieved. The proposed metamaterial is well adapted to variety of slow-light applications in the infrared and optical range.
Planar waveguide amplifiers and laser in erbium doped silica
DEFF Research Database (Denmark)
Guldberg-Kjær, Søren Andreas; Kristensen, Martin
1999-01-01
lightwave circuits, as well as provide the gain medium for integrated planar waveguide lasers. The work and the obtained results are presented in this thesis: The manufacturing of silica thin films is described and it is shown that the refractive index o fthe films can be controlled by germanium co...... fluorescence level. In addition the first measurement of the diffusion coefficient of erbim in silica is presented and it is shown that erbium rich precipitates are formed in areas of high erbium concentration. The manufacturing of planar waveguide structures using RIE (Reactive Ion Etching) is described...
Frost, Robert; Porter, David A; Miller, Karla L; Jezzard, Peter
2012-08-01
Single-shot echo-planar imaging has been used widely in diffusion magnetic resonance imaging due to the difficulties in correcting motion-induced phase corruption in multishot data. Readout-segmented EPI has addressed the multishot problem by introducing a two-dimensional nonlinear navigator correction with online reacquisition of uncorrectable data to enable acquisition of high-resolution diffusion data with reduced susceptibility artifact and T*(2) blurring. The primary shortcoming of readout-segmented EPI in its current form is its long acquisition time (longer than similar resolution single-shot echo-planar imaging protocols by approximately the number of readout segments), which limits the number of diffusion directions. By omitting readout segments at one side of k-space and using partial Fourier reconstruction, readout-segmented EPI imaging times could be reduced. In this study, the effects of homodyne and projection onto convex sets reconstructions on estimates of the fractional anisotropy, mean diffusivity, and diffusion orientation in fiber tracts and raw T(2)- and trace-weighted signal are compared, along with signal-to-noise ratio results. It is found that projections onto convex sets reconstruction with 3/5 segments in a 2 mm isotropic diffusion tensor image acquisition and 9/13 segments in a 0.9 × 0.9 × 4.0 mm(3) diffusion-weighted image acquisition provide good fidelity relative to the full k-space parameters. This allows application of readout-segmented EPI to tractography studies, and clinical stroke and oncology protocols. Copyright © 2011 Wiley-Liss, Inc.
Sabry, R.; Moslem, W. M.; Shukla, P. K.
2009-02-01
Ion-acoustic envelope solitary waves in a very dense plasma comprised of the electrons, positrons and ions are investigated. For this purpose, the quantum hydrodynamic model and the Poisson equation are used. A modified nonlinear Schrödinger equation is derived by employing the reductive perturbation method. The effects of the quantum correction and of the positron density on the propagation and stability of the envelope solitary waves are examined. The nonplanar (cylindrical/spherical) geometry gives rise to an instability period. The latter cannot exist for planar case and it affected by the quantum parameters, as well as the positron density. The present investigation is relevant to white dwarfs.
Analyze of Ortho-SUV™, software base hybrid fixation on three planar femur deformity
Directory of Open Access Journals (Sweden)
Mohammadreza Effatparvar
2017-05-01
Full Text Available Background: Application of Hybrid 6 degrees of freedom fixation could lead to space motion in each 3 anatomic plates together and decrease the time of complex deformities correction. This study is an investigation on the function of hybrid external fixation and the influence of it on decreasing the treatment time. About this case utilize of Ortho-SUV Frame (OSF system is explained for the first time in Iran and report of its novel. These robotic systems are divided into two groups: active and passive, about active system all movements are done by actuators in joints and links. And in passive, the system needs an operator or patient to actuates Sturats by hand. Methods: The femur bone has been investigated was non:union: with deformity in sagittal, frontal and transversal planes. Ilizarov external fixation was applicate firstly, with this condition that the OSF systems jacks were replaced instead of simple rods in side of fracture. Software work was done on February of 2016 in Ayatollah Taleghani Hospital, Tehran, Iran. Fractures were happened in a car accident and some other operating were perforemed for this patient without any result. Results: The correction of studied deformity needs 3 planar moving. Acting this movement by Ilizarov requirements 33 mm displacement in frontal plane, 12 mm horizontal distraction and 48 mm displacement in sagittal plane. Due to the rate of correction in Ilizarov which is 1 mm per day, this bone needs 93 days for general correction and three times changing in shape of rings connections. While, by using the hybrid external fixation, all displacements were corrected in 46 days and first connection had supported all planes. Conclusion: According to that the decreasing of treatment time is one of the main goal, the hybrid external fixation systems could be an appointment choice in complex deformities and replaced with some common fixation. In addition to, using of updated software increases the accuracy of
Three-loop massive form factors: complete light-fermion corrections for the vector current
Lee, Roman N.; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias
2018-03-01
We compute the three-loop QCD corrections to the massive quark-anti-quark-photon form factors F 1 and F 2 involving a closed loop of massless fermions. This subset is gauge invariant and contains both planar and non-planar contributions. We perform the reduction using FIRE and compute the master integrals with the help of differential equations. Our analytic results can be expressed in terms of Goncharov polylogarithms. We provide analytic results for all master integrals which are not present in the large- N c calculation considered in refs. [1, 2].
Effects of planar and non-planar driver-side mirrors on age-related discomfort-glare responses
Lockhart, Thurmon E.; Atsumi, Bunji; Ghosh, Arka; Mekaroonreung, Haruetai; Spaulding, Jeremy
2010-01-01
In this study, we evaluated subjective nighttime discomfort-glare responses on three different types of planar and non-planar driver-side mirrors on two age groups. Fifty-six individuals (28 young [18–35 years] and 28 old [65 years and over]) participated in this experiment. Subjective discomfort-glare rating scores on three different types of driver-side mirrors were assessed utilizing De Boer's rating scale in a controlled nighttime driving environment (laboratory ambient illuminant level—l lux with headlight turned off). Three driver-side mirrors included planar “flat mirror”: radius of curvature 242650.92 mm, reflectivity 0.60114, and surface reflectance 0.60568; “curved mirror”: radius of curvature 1433.3 mm, reflectivity 0.21652, and surface reflectance 0.58092; “blue mirror”: radius of curvature 1957.1 mm, reflectivity 0.25356, and surface reflectance 0.54585. The results indicated that with the same glare level (as measured by angle of incidence and illuminance in front of the eyes), older adults reported worse feelings of glare than their younger counterparts. Furthermore, the results indicated that both young and older adults reported worse feelings of glare for planar driver-side mirror than non-planar driver-side mirrors. These results suggest that older adults' criterion of discomfort-glare is more sensitive than their younger counterparts, and importantly, the non-planar driver-side mirrors can be beneficial in terms of reducing nighttime discomfort-glare for both the young and the elderly. PMID:20582252
Zimmerman, Brian E; Grošev, Darko; Buvat, Irène; Coca Pérez, Marco A; Frey, Eric C; Green, Alan; Krisanachinda, Anchali; Lassmann, Michael; Ljungberg, Michael; Pozzo, Lorena; Quadir, Kamila Afroj; Terán Gretter, Mariella A; Van Staden, Johann; Poli, Gian Luca
2017-06-01
Accurate quantitation of activity provides the basis for internal dosimetry of targeted radionuclide therapies. This study investigated quantitative imaging capabilities at sites with a variety of experience and equipment and assessed levels of errors in activity quantitation in Single-Photon Emission Computed Tomography (SPECT) and planar imaging. Participants from 9 countries took part in a comparison in which planar, SPECT and SPECT with X ray computed tomography (SPECT-CT) imaging were used to quantify activities of four epoxy-filled cylinders containing 133 Ba, which was chosen as a surrogate for 131 I. The sources, with nominal volumes of 2, 4, 6 and 23mL, were calibrated for 133 Ba activity by the National Institute of Standards and Technology, but the activity was initially unknown to the participants. Imaging was performed in a cylindrical phantom filled with water. Two trials were carried out in which the participants first estimated the activities using their local standard protocols, and then repeated the measurements using a standardized acquisition and analysis protocol. Finally, processing of the imaging data from the second trial was repeated by a single centre using a fixed protocol. In the first trial, the activities were underestimated by about 15% with planar imaging. SPECT with Chang's first order attenuation correction (Chang-AC) and SPECT-CT overestimated the activity by about 10%. The second trial showed moderate improvements in accuracy and variability. Planar imaging was subject to methodological errors, e.g., in the use of a transmission scan for attenuation correction. The use of Chang-AC was subject to variability from the definition of phantom contours. The project demonstrated the need for training and standardized protocols to achieve good levels of quantitative accuracy and precision in a multicentre setting. Absolute quantification of simple objects with no background was possible with the strictest protocol to about 6% with planar
Static And Kinematic Formulation Of Planar Reciprocal Assemblies
DEFF Research Database (Denmark)
Parigi, Dario; Kirkegaard, Poul Henning
2013-01-01
Planar reciprocal frames are two dimensional structures formed by elements joined together according to the principle of structural reciprocity. In this paper a rigorous formulation of the static and kinematic problem is proposed and developed by extending the work on pin-jointed assemblies...
Graphene Q-switched Yb:KYW planar waveguide laser
Kim, Jun Wan; Choi, Sun Young; Aravazhi, S.; Pollnau, Markus; Griebner, Uwe; Petrov, Valentin; Bae, Sukang; Ahn, Kwang Jun; Yeom, Dong-Il; Rotermund, Fabian
A diode-pumped Yb:KYW planar waveguide laser, single-mode Q-switched by evanescent-field interaction with graphene, is demonstrated for the first time. Few-layer graphene grown by chemical vapor deposition is transferred onto the top of a guiding layer, which initiates stable Q-switched operation in
Homography-based grasp tracking for planar objects
Carloni, Raffaella; Recatala, Gabriel; Melchiorri, Claudio; Sanz, Pedro J.; Cervera, Enric
The visual tracking of grasp points is an essential operation for the execution of an approaching movement of a robot arm to an object: the grasp points are used as features for the definition of the control law. This work describes a strategy for tracking grasps on planar objects based on the use
On Distributed Computation in Noisy Random Planar Networks
Kanoria, Y.; Manjunath, D.
2007-01-01
We consider distributed computation of functions of distributed data in random planar networks with noisy wireless links. We present a new algorithm for computation of the maximum value which is order optimal in the number of transmissions and computation time.We also adapt the histogram computation algorithm of Ying et al to make the histogram computation time optimal.
The planar algebra of a semisimple and cosemisimple Hopf algebra
Indian Academy of Sciences (India)
M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22
[TngGlk] Etingof Pavel and Gelaki Shlomo, On finite-dimensional semisimple and cosemisimple Hopf algebras in positive characteristic. Int. Math. Res. Notices,. 16 (1998) 851–864. [DasKdy] Das Paramita and Vijay Kodiyalam, Planar algebras and the Ocneanu–. Szymanski theorem, Proc. AMS, 133 (2005) 2751–2759.
Static and kinematic formulation of planar reciprocal assemblies
DEFF Research Database (Denmark)
Parigi, Dario; Sassone, Mario; Kirkegaard, Poul Henning
2014-01-01
Planar reciprocal frames are two dimensional structures formed by elements joined together according to the principle of structural reciprocity. In this paper a rigorous formulation of the static and kinematic problem is proposed and developed extending the theory of pin-jointed assemblies...
Characterization of a planar microcoil for implantable microsystems
Neagu, Cristina; Rusu, C.R.; Jansen, Henricus V.; Smith, A.; Gardeniers, Johannes G.E.; Elwenspoek, Michael Curt
This paper discusses the modelling, design and characterization of planar microcoils to be used in telemetry systems that supply energy to miniaturized implants. Parasitic electrical effects that may become important at a.c. frequencies of several megahertz are evaluated. The fabrication process and
A nitrate sensitive planar optode; performance and interferences
DEFF Research Database (Denmark)
Pedersen, Lasse; Dechesne, Arnaud; Smets, Barth F.
2015-01-01
We present a newly developed nitrate sensitive planar optode. It exhibits a linear response to nitrate from 1 to 50 mM at pH 8.0, a fast response time below 10 s and a good lifetime, allowing for fast two dimensional nitrate measurements over long periods of time. Interference from nitrite...
I/O-Efficient Dynamic Planar Range Skyline Queries
DEFF Research Database (Denmark)
Kejlberg-Rasmussen, Casper; Tsakalidis, Konstantinos; Tsichlas, Kostas
{n}{B^{1-\\epsilon}})$ blocks of space, for $n$ input planar points, $t$ reported points, and parameter $0 \\leq \\epsilon \\leq 1$. We obtain the result by extending Sundar's priority queues with attrition to support the operations \\textsc{DeleteMin} and \\textsc{CatenateAndAttrite} in $\\bigO (1)$ worst case I...
Finite element and perturbative study of buffered leaky planar waveguides
Uranus, H.P.; Hoekstra, Hugo; van Groesen, Embrecht W.C.
2005-01-01
The effects of the presence of a high-index medium in the proximity of planar waveguiding structures that makes up buffered leaky waveguides, were studied using a finite element method (FEM) leaky mode solver and a perturbation method. Various phenomena observed in the FEM results were interpreted
Synthesis of square-planar aluminum(III) complexes.
Thompson, Emily J; Myers, Thomas W; Berben, Louise A
2014-12-15
The synthesis of two four-coordinate and square planar (SP) complexes of aluminum(III) is presented. Reaction of a phenyl-substituted bis(imino)pyridine ligand that is reduced by two electrons, Na2((Ph)I2P(2-)), with AlCl3 afforded five-coordinate [((Ph)I2P(2-))Al(THF)Cl] (1). Square-planar [((Ph)I2P(2-))AlCl] (2) was obtained by performing the same reaction in diethyl ether followed by lyphilization of 2 from benzene. The four-coordinate geometry index for 2, τ4, is 0.22, where 0 would be a perfectly square-planar molecule. The analogous aluminum hydride complex, [((Ph)I2P(2-))AlH] (3), is also square-planar, and was characterized crystallographically and has τ4=0.13. Both 2 and 3 are Lewis acidic and bind 2,6-lutidine. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Characteristics and optimisation of vertical and planar tunnelling-FETs
International Nuclear Information System (INIS)
Sterkel, M; Wang, P-F; Nirschl, T; Fabel, B; Bhuwalka, K K; Schulze, J; Eisele, I; Schmitt-Landsiedel, D; Hansch, W
2005-01-01
Scaling MOSFETs becomes more and more difficult. The tunnelling-FET is a possible successor of today's MOSFET with better scaling possibilities. Two different device structures, a vertical and a planar version of a tunnelling-FET are presented and evaluated
A planar microfluidic mixer based on logarithmic spirals
International Nuclear Information System (INIS)
Scherr, Thomas; Nandakumar, Krishnaswamy; Quitadamo, Christian; Tesvich, Preston; Park, Daniel Sang-Won; Hayes, Daniel; Monroe, W Todd; Tiersch, Terrence; Choi, Jin-Woo
2012-01-01
A passive, planar micromixer design based on logarithmic spirals is presented. The device was fabricated using polydimethylsiloxane soft photolithography techniques, and mixing performance was characterized via numerical simulation and fluorescent microscopy. Mixing efficiency initially declined as the Reynolds number increased, and this trend continued until a Reynolds number of 15 where a minimum was reached at 53%. Mixing efficiency then began to increase reaching a maximum mixing efficiency of 86% at Re = 67. Three-dimensional (3D) simulations of fluid mixing in this design were compared to other planar geometries such as the Archimedes spiral and Meandering-S mixers. The implementation of logarithmic curvature offers several unique advantages that enhance mixing, namely a variable cross-sectional area and a logarithmically varying radius of curvature that creates 3D Dean vortices. These flow phenomena were observed in simulations with multilayered fluid folding and validated with confocal microscopy. This design provides improved mixing performance over a broader range of Reynolds numbers than other reported planar mixers, all while avoiding external force fields, more complicated fabrication processes and the introduction of flow obstructions or cavities that may unintentionally affect sensitive or particulate-containing samples. Due to the planar design requiring only single-step lithographic features, this compact geometry could be easily implemented into existing micro-total analysis systems requiring effective rapid mixing. (paper)
Chimera states in a population of identical oscillators under planar ...
Indian Academy of Sciences (India)
Abstract. We report the existence of chimera states in an assembly of identical nonlinear oscil- lators that are globally linked to each other in a simple planar cross-coupled form. The rotational symmetry breaking of the coupling term appears to be responsible for the emergence of these col- lective states that display a ...
Planar Hall effect sensor with magnetostatic compensation layer
DEFF Research Database (Denmark)
Dalslet, Bjarke Thomas; Donolato, Marco; Hansen, Mikkel Fougt
2012-01-01
Demagnetization effects in cross-shaped planar Hall effect sensors cause inhomogeneous film magnetization and a hysteretic sensor response. Furthermore, when using sensors for detection of magnetic beads, the magnetostatic field from the sensor edges attracts and holds magnetic beads near the sen...
Development of Planar Metal Supported SOFC with Novel Cermet Anode
DEFF Research Database (Denmark)
Blennow Tullmar, Peter; Hjelm, Johan; Klemensø, Trine
2009-01-01
, into which electrocatalytically active materials are infiltrated after sintering. The paper presents the recent results on the electrochemical performance and durability of the novel planar metal-supported SOFC design. The results presented in the paper show that the novel cell and anode design has...... a promising performance and durability at a broad range of temperatures and is especially suitable for intermediate temperature operation....
A QQ→QQ planar double box in canonical form
Directory of Open Access Journals (Sweden)
Marco S. Bianchi
2018-02-01
Full Text Available We consider a planar double box with four massive external momenta and two massive internal propagators. We derive the system of differential equations for the relevant master integrals, cast it in canonical form, write it as a dlog form and solve it in terms of iterated integrals up to depth four.
Slices: A shape-proxy based on planar sections
McCrae, James
2011-12-01
Minimalist object representations or shape-proxies that spark and inspire human perception of shape remain an incompletely understood, yet powerful aspect of visual communication. We explore the use of planar sections, i.e., the contours of intersection of planes with a 3D object, for creating shape abstractions, motivated by their popularity in art and engineering. We first perform a user study to show that humans do define consistent and similar planar section proxies for common objects. Interestingly, we observe a strong correlation between user-defined planes and geometric features of objects. Further we show that the problem of finding the minimum set of planes that capture a set of 3D geometric shape features is both NP-hard and not always the proxy a user would pick. Guided by the principles inferred from our user study, we present an algorithm that progressively selects planes to maximize feature coverage, which in turn influence the selection of subsequent planes. The algorithmic framework easily incorporates various shape features, while their relative importance values are computed and validated from the user study data. We use our algorithm to compute planar slices for various objects, validate their utility towards object abstraction using a second user study, and conclude showing the potential applications of the extracted planar slice shape proxies.
Planar Hall effect sensor for magnetic micro- and nanobead detection
DEFF Research Database (Denmark)
Ejsing, Louise Wellendorph; Hansen, Mikkel Fougt; Menon, Aric Kumaran
2004-01-01
Magnetic bead sensors based on the planar Hall effect in thin films of exchange-biased permalloy have been fabricated and characterized. Typical sensitivities are 3 muV/Oe mA. The sensor response to an applied magnetic field has been measured without and with coatings of commercially available 2 ...
Low-frequency noise in planar Hall effect bridge sensors
DEFF Research Database (Denmark)
Persson, Anders; Bejhedb, R.S.; Bejhed, R.S.
2011-01-01
The low-frequency characteristics of planar Hall effect bridge sensors are investigated as function of the sensor bias current and the applied magnetic field. The noise spectra reveal a Johnson-like spectrum at high frequencies, and a 1/f-like excess noise spectrum at lower frequencies, with a kn...
Cut cancellation in the planar integral equation for the Reggeon
International Nuclear Information System (INIS)
Bishari, M.; Veneziano, G.
1975-01-01
Planar unitarity for the Reggeon, analyticity and the multi-Regge assumption with cluster production lead to integral equations of the Chew-Goldberger-Low type with separable self-consistent kernel. Contrary to common prejudice, the authors show the existence of solutions exhibiting moving poles and exact, non-perturbative cancellation of the cut. Previously studied consistency conditions are rederived. (Auth.)
The planar algebra associated to a Kac algebra
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
and not just the plane). ..... We will need the following facts from [L], which we state as a proposition for conve- nience of reference. PROPOSITION 3.3. Suppose P (L; R) is an exchange relation planar algebra. Then,. (i) dimPn(L; R) < ∞ ∀n;.
Equilibrium points in the generalised photogravitational non-planar ...
African Journals Online (AJOL)
We generalised the photogravitational non-planar restricted three body problem by considering the smaller primary as an oblate spheroid. With both the primaries radiating, we located the equilibrium points which lie outside the orbital plane, contrary to the classical case. Besides finding the equations of motion of the ...
Analysis and design of efficient planar leaky-wave antennas
Ettore, M.
2008-01-01
This thesis deals with the effective design of planar leaky-wave antennas. The work describes a methodology based on the polar expansion of Green's function representations to address very different geometrical configurations which might appear to have little in common. In fact leaky waves with
A Nafion -based co-planar electrode amperometric sensor for ...
Indian Academy of Sciences (India)
Administrator
Dedicated to the memory of the late Professor S K Rangarajan ... A co-planar electrode device, fabricated with all electrodes (working, counter and reference) on the same face of a Nafion. ® polymer electrolyte membrane, is proposed for the amperometric detection of gaseous methanol using Pt as the working electrode.
Planar electron beams in a wiggler magnet array
Indian Academy of Sciences (India)
2013-02-01
Feb 1, 2013 ... Planar electron beams in a wiggler magnet array. ARTI HADAP1,∗ and K C MITTAL2. 1General Engineering Department, Terna Engineering College, Nerul, Navi Mumbai 400 706,. India. 2Accelerator and Pulsed Power Division, Bhabha Atomic Research Centre, Trombay,. Mumbai 400 085, India. ∗.
Rhombic embeddings of planar graphs with faces of degree 4
Kenyon, Richard; Schlenker, Jean-Marc
2003-01-01
Given a finite or infinite planar graph all of whose faces have degree 4, we study embeddings in the plane in which all edges have length 1, that is, in which every face is a rhombus. We give a necessary and sufficient condition for the existence of such an embedding, as well as a description of the set of all such embeddings.
Instantaneous planar pressure determination from PIV in turbulent flow
De Kat, R.; Van Oudheusden, B.W.
2011-01-01
This paper deals with the determination of instantaneous planar pressure fields from velocity data obtained by particle image velocimetry (PIV) in turbulent flow. The operating principles of pressure determination using a Eulerian or a Lagrangian approach are described together with theoretical
Sacrificial wafer bonding for planarization after very deep etching
Spiering, V.L.; Spiering, Vincent L.; Berenschot, Johan W.; Elwenspoek, Michael Curt; Fluitman, J.H.J.
A new technique is presented that provides planarization after a very deep etching step in silicon. This offers the possibility for as well resist spinning and layer patterning as realization of bridges or cantilevers across deep holes or grooves. The sacrificial wafer bonding technique contains a
Planar defects and dislocations in transition-metal disilicides
Czech Academy of Sciences Publication Activity Database
Paidar, Václav; Čák, M.; Šob, Mojmír; Inui, H.
2015-01-01
Roč. 58, Mar (2015), s. 43-49 ISSN 0966-9795 R&D Projects: GA ČR GAP108/12/0144 Institutional support: RVO:68378271 ; RVO:68081723 Keywords : intermetallics * dislocation structure * planar fault s * ab-initio calculation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.541, year: 2015
Automated curved planar reformation of 3D spine images
International Nuclear Information System (INIS)
Vrtovec, Tomaz; Likar, Bostjan; Pernus, Franjo
2005-01-01
Traditional techniques for visualizing anatomical structures are based on planar cross-sections from volume images, such as images obtained by computed tomography (CT) or magnetic resonance imaging (MRI). However, planar cross-sections taken in the coordinate system of the 3D image often do not provide sufficient or qualitative enough diagnostic information, because planar cross-sections cannot follow curved anatomical structures (e.g. arteries, colon, spine, etc). Therefore, not all of the important details can be shown simultaneously in any planar cross-section. To overcome this problem, reformatted images in the coordinate system of the inspected structure must be created. This operation is usually referred to as curved planar reformation (CPR). In this paper we propose an automated method for CPR of 3D spine images, which is based on the image transformation from the standard image-based to a novel spine-based coordinate system. The axes of the proposed spine-based coordinate system are determined on the curve that represents the vertebral column, and the rotation of the vertebrae around the spine curve, both of which are described by polynomial models. The optimal polynomial parameters are obtained in an image analysis based optimization framework. The proposed method was qualitatively and quantitatively evaluated on five CT spine images. The method performed well on both normal and pathological cases and was consistent with manually obtained ground truth data. The proposed spine-based CPR benefits from reduced structural complexity in favour of improved feature perception of the spine. The reformatted images are diagnostically valuable and enable easier navigation, manipulation and orientation in 3D space. Moreover, reformatted images may prove useful for segmentation and other image analysis tasks
Determination of crystallographic and macroscopic orientation of planar structures in TEM
DEFF Research Database (Denmark)
Huang, X.; Liu, Q.
1998-01-01
With the aid of a double-tilt holder in a transmission electron microscope (TEM), simple methods are described for determination of the crystallographic orientation of a planar structure and for calculation of the macroscopic orientation of the planar structure. The correlation between a planar...... taken at tilted positions, can be transformed to the real macroscopic orientation of the planar structures with estimated error of about +/- 2 degrees. (C) 1998 Elsevier Science B.V. All rights reserved....
Analysis and correction of imperfections in the image-intensifier TV-digitizer imaging chain
International Nuclear Information System (INIS)
Boone, J.M.; Seibert, J.A.; Barrett, W.A.
1989-01-01
Image-intensifier/television/video-digitizer (II/TV/VD) systems are commonly available tools for digital planar image acquisition in radiology. However, the well-known shortcomings of these systems limit their usefulness in research applications, for which quantitatively correct images are required. The authors have investigated software correction techniques by which both the spatial and gray-scale quantitative integrity can be restored to II/TV/VD systems. They have used previously reported and new correction techniques to reduce veiling glare, pincushion distortion, and vignetting and residual shading artifacts. The results show that excellent quantitative integrity can be achieved by use of straightforward artifact-reduction techniques
Loop Corrections to Supergravity on AdS5×S5
Alday, Luis F.; Bissi, Agnese
2017-10-01
We consider the four-point correlator of the stress-energy tensor multiplet in N =4 super Yang-Mills theory. In the planar limit and at large 't Hooft coupling, such a correlator is given by the corresponding holographic correlation function in IIB supergravity on AdS5×S5. We consider subleading corrections in the number of colors, i.e., order 1 /N4, at large 't Hooft coupling. This corresponds to loop corrections to the supergravity result. Consistency conditions, most notably, crossing symmetry, constrain the form of such corrections and lead to a complete determination of the spectrum of leading-twist intermediate operators.
Loop Corrections to Supergravity on AdS_{5}×S^{5}.
Alday, Luis F; Bissi, Agnese
2017-10-27
We consider the four-point correlator of the stress-energy tensor multiplet in N=4 super Yang-Mills theory. In the planar limit and at large 't Hooft coupling, such a correlator is given by the corresponding holographic correlation function in IIB supergravity on AdS_{5}×S^{5}. We consider subleading corrections in the number of colors, i.e., order 1/N^{4}, at large 't Hooft coupling. This corresponds to loop corrections to the supergravity result. Consistency conditions, most notably, crossing symmetry, constrain the form of such corrections and lead to a complete determination of the spectrum of leading-twist intermediate operators.
Eliás, P.; Strichovanec, P.; Kostic, I.; Novák, J.
2006-12-01
A draping technique was tested for the deposition of positive-tone AZ5214-E photo-resist layers on non-planar (1 0 0)-oriented III-V substrates, which had a variety of three-dimensional (3D) topographies micromachined in them that consisted, e.g., of mesa ridges confined to side facets with variable tilt, inverted pyramidal holes and stubs confined to perpendicular side facets. All objects were sharp-edged. In each draping experiment, an AZ5214-E sheet was (1) formed floating on the water surface, (2) lowered onto a non-planar substrate and (3) draped over it during drying to form either self-sustained, or conformal, or planarizing layers over the non-planar substrates. The draping process is based on the depression of the glass transition temperature Tg of AZ5214-E material induced by penetrant water molecules that interact with AZ5214-E. During the process, the molecules are initially trapped under an AZ5214-E sheet and then transported out through the sheet via permeation. The water-AZ5214-E interaction modifies the stiffness κ of the sheet. The magnitude of the effect depends on temperature T and on partial water vapour pressure difference p(T, P, κ): the net effect is that Tg = f(C(T, P), p(T, P, κ)) is lowered as the concentration C of water increases with T and p, where P is the permeability of the sheet. The interaction depressed the Tg of the sheets as low as or lower than 53 °C for 6 µm thick sheets. At room temperature T Tg, the sheet becomes rubbery and mouldable by adhesion and capillary forces. As a result, it can either contour or planarize the topography depending on its geometry and thickness of the sheet.
Students' Attitude toward Correction
Directory of Open Access Journals (Sweden)
Rinda Fitriana
2017-10-01
Full Text Available Students’ attitudes influence their decision to whether or not accept the teachers’ feedback. Therefore, questionnaire was administered to one hundred and ninety-six twelfth grade of vocational high school students, wherein, ten of them were involved in interview, to figure out their perspective concerning to the teachers’ correction on their oral production. From both instruments, it is found that the students preferred the teachers as the correctors, although, they did not mind for peer correction. They also expected the teachers to give correction at every time they did error and for all types of errors. Additionally, students agreed that teachers’ personality and their way of teaching influenced their willingness to accept the corrective feedback.
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Eyeglasses for Vision Correction
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Holdsworth, Samantha J; Yeom, Kristen W; Moseley, Michael E; Skare, S
2015-05-01
Susceptibility-weighted imaging (SWI) in neuroimaging can be challenging due to long scan times of three-dimensional (3D) gradient recalled echo (GRE), while faster techniques such as 3D interleaved echo-planar imaging (iEPI) are prone to motion artifacts. Here we outline and implement a 3D short-axis propeller echo-planar imaging (SAP-EPI) trajectory as a faster, motion-correctable approach for SWI. Experiments were conducted on a 3T MRI system. The 3D SAP-EPI, 3D iEPI, and 3D GRE SWI scans were acquired on two volunteers. Controlled motion experiments were conducted to test the motion-correction capability of 3D SAP-EPI. The 3D SAP-EPI SWI data were acquired on two pediatric patients as a potential alternative to 2D GRE used clinically. The 3D GRE images had a better target resolution (0.47 × 0.94 × 2 mm, scan time = 5 min), iEPI and SAP-EPI images (resolution = 0.94 × 0.94 × 2 mm) were acquired in a faster scan time (1:52 min) with twice the brain coverage. SAP-EPI showed motion-correction capability and some immunity to undersampling from rejected data. While 3D SAP-EPI suffers from some geometric distortion, its short scan time and motion-correction capability suggest that SAP-EPI may be a useful alternative to GRE and iEPI for use in SWI, particularly in uncooperative patients. © 2014 Wiley Periodicals, Inc.
International Nuclear Information System (INIS)
Kalemis, A; Bailey, D L; Flower, M A; Lord, S K; Ott, R J
2004-01-01
In this paper two tests based on statistical models are presented and used to assess, quantify and provide positional information of the existence of bias and/or variations between planar images acquired at different times but under similar conditions. In the first test a linear regression model is fitted to the data in a pixelwise fashion, using three mathematical operators. In the second test a comparison using z-scoring is used based on the assumption that Poisson statistics are valid. For both tests the underlying assumptions are as simple and few as possible. The results are presented as parametric maps of either the three operators or the z-score. The z-score maps can then be thresholded to show the parts of the images which demonstrate change. Three different thresholding methods (naive, adaptive and multiple) are presented: together they cover almost all the needs for separating the signal from the background in the z-score maps. Where the expected size of the signal is known or can be estimated, a spatial correction technique (referred to as the reef correction) can be applied. These tests were applied to flood images used for the quality control of gamma camera uniformity. Simulated data were used to check the validity of the methods. Real data were acquired from four different cameras from two different institutions using a variety of acquisition parameters. The regression model found the bias in all five simulated cases and it also found patterns of unstable regions in real data where visual inspection of the flood images did not show any problems. In comparison the z-map revealed the differences in the simulated images from as low as 1.8 standard deviations from the mean, corresponding to a differential uniformity of 2.2% over the central field of view. In all cases studied, the reef correction increased significantly the sensitivity of the method and in most cases the specificity as well. The two proposed tests can be used either separately or in
Tersi, Luca; Barré, Arnaud; Fantozzi, Silvia; Stagni, Rita
2013-03-01
Model-based mono-planar and bi-planar 3D fluoroscopy methods can quantify intact joints kinematics with performance/cost trade-off. The aim of this study was to compare the performances of mono- and bi-planar setups to a marker-based gold-standard, during dynamic phantom knee acquisitions. Absolute pose errors for in-plane parameters were lower than 0.6 mm or 0.6° for both mono- and bi-planar setups. Mono-planar setups resulted critical in quantifying the out-of-plane translation (error mono- (error mono-planar in-plane pose parameters is comparable to bi-planar, but with halved computational costs, halved segmentation time and halved ionizing radiation dose. Bi-planar analysis better compensated for the out-of-plane uncertainty that is differently propagated to relative kinematics depending on the setup. To take its full benefits, the motion task to be investigated should be designed to maintain the joint inside the visible volume introducing constraints with respect to mono-planar analysis.
Poser, Benedikt A; Barth, Markus; Goa, Pål-Erik; Deng, Weiran; Stenger, V Andrew
2013-01-01
Echo planar imaging (EPI) is most commonly used for blood oxygen level-dependent fMRI, owing to its sensitivity and acquisition speed. A major problem with EPI is Nyquist (N/2) ghosting, most notably at high field. EPI data are acquired under an oscillating readout gradient and hence vulnerable to gradient imperfections such as eddy current delays and off-resonance effects, as these cause inconsistencies between odd and even k-space lines after time reversal. We propose a straightforward and pragmatic method herein termed "interleaved dual echo with acceleration (IDEA) EPI": two k-spaces (echoes) are acquired under the positive and negative readout lobes, respectively, by performing phase encoding blips only before alternate readout gradients. From these two k-spaces, two almost entirely ghost free images per shot can be constructed, without need for phase correction. The doubled echo train length can be compensated by parallel imaging and/or partial Fourier acquisition. The two k-spaces can either be complex averaged during reconstruction, which results in near-perfect cancellation of residual phase errors, or reconstructed into separate images. We demonstrate the efficacy of IDEA EPI and show phantom and in vivo images at both 3 T and 7 T. Copyright © 2012 Wiley Periodicals, Inc.
Geological Corrections in Gravimetry
Mikuška, J.; Marušiak, I.
2015-12-01
Applying corrections for the known geology to gravity data can be traced back into the first quarter of the 20th century. Later on, mostly in areas with sedimentary cover, at local and regional scales, the correction known as gravity stripping has been in use since the mid 1960s, provided that there was enough geological information. Stripping at regional to global scales became possible after releasing the CRUST 2.0 and later CRUST 1.0 models in the years 2000 and 2013, respectively. Especially the later model provides quite a new view on the relevant geometries and on the topographic and crustal densities as well as on the crust/mantle density contrast. Thus, the isostatic corrections, which have been often used in the past, can now be replaced by procedures working with an independent information interpreted primarily from seismic studies. We have developed software for performing geological corrections in space domain, based on a-priori geometry and density grids which can be of either rectangular or spherical/ellipsoidal types with cells of the shapes of rectangles, tesseroids or triangles. It enables us to calculate the required gravitational effects not only in the form of surface maps or profiles but, for instance, also along vertical lines, which can shed some additional light on the nature of the geological correction. The software can work at a variety of scales and considers the input information to an optional distance from the calculation point up to the antipodes. Our main objective is to treat geological correction as an alternative to accounting for the topography with varying densities since the bottoms of the topographic masses, namely the geoid or ellipsoid, generally do not represent geological boundaries. As well we would like to call attention to the possible distortions of the corrected gravity anomalies. This work was supported by the Slovak Research and Development Agency under the contract APVV-0827-12.
2015-01-01
This book provides a comprehensive overview of the theoretical concepts and experimental applications of planar waveguides and other confined geometries, such as optical fibres. Covering a broad array of advanced topics, it begins with a sophisticated discussion of planar waveguide theory, and covers subjects including efficient production of planar waveguides, materials selection, nonlinear effects, and applications including species analytics down to single-molecule identification, and thermo-optical switching using planar waveguides. Written by specialists in the techniques and applications covered, this book will be a useful resource for advanced graduate students and researchers studying planar waveguides and optical fibers.
Comparison of Planar Fractal Filters on Defected Ground Substrate
Directory of Open Access Journals (Sweden)
M. Kufa
2012-12-01
Full Text Available The paper discusses approaches to the reduction of dimensions of planar filters (microstrip ones and coplanar ones. Filter dimensions are reduced by applying the fractal theory to the geometry of a filter, and by the defecting of the ground plane of a filter. An optimum combination of both approaches enables us to reach smaller dimensions of planar filters and protect other parameters. In order to demonstrate advantages of the fractal defected ground approach, we review the designs of existing low-pass filters with defected ground structures (DGS. Results produced by simulations of these filters are compared with results of simulations of a novel fractal DGS filter. The investigated filters are manufactured and measured.
Planar Pixel Sensors for the ATLAS Upgrade: Beam Tests results
Weingarten, J
2012-01-01
The performance of planar silicon pixel sensors, in development for the ATLAS Insertable B-Layer and High Luminosity LHC (HL-LHC) upgrades, has been examined in a series of beam tests at the CERN SPS facilities since 2009. Salient results are reported on the key parameters, including the spatial resolution, the charge collection and the charge sharing between adjacent cells, for different bulk materials and sensor geometries. Measurements are presented for n+-in-n pixel sensors irradiated with a range of fluences and for p-type silicon sensors with various layouts from different vendors. All tested sensors were connected via bump-bonding to the ATLAS Pixel read-out chip. The tests reveal that both n-type and p-type planar sensors are able to collect significant charge even after the lifetime fluence expected at the HL-LHC.
Planar patch-clamp force microscopy on living cells
Energy Technology Data Exchange (ETDEWEB)
Pamir, Evren [Center for Nano Science, Ludwig-Maximilians University, Amalienstr 54, 80799 Munich (Germany); George, Michael; Fertig, Niels [Nanion Technologies GmbH, Erzgiessereistr. 4, 80335 Munich (Germany); Benoit, Martin [Center for Nano Science, Ludwig-Maximilians University, Amalienstr 54, 80799 Munich (Germany)], E-mail: martin.benoit@physik.uni-muenchen.de
2008-05-15
Here we report a new combination of the patch-clamp technique with the atomic force microscope (AFM). A planar patch-clamp chip microstructured from borosilicate glass was used as a support for mechanical probing of living cells. The setup not only allows for immobilizing even a non-adherent cell for measurements of its mechanical properties, but also for simultaneously measuring the electrophysiological properties of a single cell. As a proof of principle experiment we measured the voltage-induced membrane movement of HEK293 and Jurkat cells in the whole-cell voltage clamp configuration. The results of these measurements are in good agreement with previous studies. By using the planar patch-clamp chip for immobilization, the AFM not only can image non-adhering cells, but also gets easily access to an electrophysiologically controlled cellular probe at low vibrational noise.
Planar Bragg Grating Sensors—Fabrication and Applications: A Review
Directory of Open Access Journals (Sweden)
I. J. G. Sparrow
2009-01-01
Full Text Available We discuss the background and technology of planar Bragg grating sensors, reviewing their development and describing the latest developments. The physical operating principles are discussed, relating device operation to user requirements. Recent performance of such devices includes a planar Bragg grating sensor design which allows refractive index resolution of 1.9×10−6 RIU and temperature resolution of 0.03∘C. This sensor design is incorporated into industrialised applications allowing the sensor to be used for real time sensing in intrinsically safe, high-pressure pipelines, or for insertion probe applications such as fermentation. Initial data demonstrating the ability to identify solvents and monitor long term industrial processes is presented. A brief review of the technology used to fabricate the sensors is given along with examples of the flexibility afforded by the technique.
Performance of planar heterojunction perovskite solar cells under light concentration
Directory of Open Access Journals (Sweden)
Aaesha Alnuaimi
2016-11-01
Full Text Available In this work, we present 2D simulation of planar heterojunction perovskite solar cells under high concentration using physics-based TCAD. The performance of planar perovskite heterojunction solar cells is examined up to 1000 suns. We analyze the effect of HTM mobility and band structure, surface recombination velocities at interfaces and the effect of series resistance under concentrated light. The simulation results revealed that the low mobility of HTM material limits the improvement in power conversation efficiency of perovskite solar cells under concentration. In addition, large band offset at perovskite/HTM interface contributes to the high series resistance. Moreover, losses due to high surface recombination at interfaces and the high series resistance deteriorate significantly the performance of perovskite solar cells under concentration.
A fabrication guide for planar silicon quantum dot heterostructures
Spruijtenburg, Paul C.; Amitonov, Sergey V.; van der Wiel, Wilfred G.; Zwanenburg, Floris A.
2018-04-01
We describe important considerations to create top-down fabricated planar quantum dots in silicon, often not discussed in detail in literature. The subtle interplay between intrinsic material properties, interfaces and fabrication processes plays a crucial role in the formation of electrostatically defined quantum dots. Processes such as oxidation, physical vapor deposition and atomic-layer deposition must be tailored in order to prevent unwanted side effects such as defects, disorder and dewetting. In two directly related manuscripts written in parallel we use techniques described in this work to create depletion-mode quantum dots in intrinsic silicon, and low-disorder silicon quantum dots defined with palladium gates. While we discuss three different planar gate structures, the general principles also apply to 0D and 1D systems, such as self-assembled islands and nanowires.
Topological transition in disordered planar matching: combinatorial arcs expansion
Lokhov, Andrey Y.; Valba, Olga V.; Nechaev, Sergei K.; Tamm, Mikhail V.
2014-12-01
In this paper, we investigate analytically the properties of the disordered Bernoulli model of planar matching. This model is characterized by a topological phase transition, yielding complete planar matching solutions only above a critical density threshold. We develop a combinatorial procedure of arcs expansion that explicitly takes into account the contribution of short arcs and allows us to obtain an accurate analytical estimation of the critical value by reducing the global constrained problem to a set of local ones. As an application to a toy representation of the RNA secondary structures, we suggest generalized models that incorporate a one-to-one correspondence between the contact matrix and the RNA-type sequence, thus giving sense to the notion of effective non-integer alphabets.
Simultaneous 2D Strain Sensing Using Polymer Planar Bragg Gratings
Rosenberger, Manuel; Eisenbeil, Waltraud; Schmauss, Bernhard; Hellmann, Ralf
2015-01-01
We demonstrate the application of polymer planar Bragg gratings for multi-axial strain sensing and particularly highlight simultaneous 2D strain measurement. A polymer planar Bragg grating (PPBG) fabricated with a single writing step in bulk polymethylmethacrylate is used for measuring both tensile and compressive strain at various angles. It is shown that the sensitivity of the PPBG strongly depends on the angle between the optical waveguide into which the grating is inscribed and the direction along which the mechanical load is applied. Additionally, a 2D PPBG fabricated by writing two Bragg gratings angularly displaced from each other into a single polymer platelet is bonded to a stainless steel plate. The two reflected wavelengths exhibit different sensitivities while tested toward tensile and compressive strain. These characteristics make 2D PPBG suitable for measuring multi-axial tensile and compressive strain. PMID:25686313
Planar LTCC transformers for high voltage flyback converters: Part II.
Energy Technology Data Exchange (ETDEWEB)
Schofield, Daryl (NASCENTechnology, Inc., Watertown, SD); Schare, Joshua M., Ph.D.; Slama, George (NASCENTechnology, Inc., Watertown, SD); Abel, David (NASCENTechnology, Inc., Watertown, SD)
2009-02-01
This paper is a continuation of the work presented in SAND2007-2591 'Planar LTCC Transformers for High Voltage Flyback Converters'. The designs in that SAND report were all based on a ferrite tape/dielectric paste system originally developed by NASCENTechnoloy, Inc, who collaborated in the design and manufacturing of the planar LTCC flyback converters. The output/volume requirements were targeted to DoD application for hard target/mini fuzing at around 1500 V for reasonable primary peak currents. High voltages could be obtained but with considerable higher current. Work had begun on higher voltage systems and is where this report begins. Limits in material properties and processing capabilities show that the state-of-the-art has limited our practical output voltage from such a small part volume. In other words, the technology is currently limited within the allowable funding and interest.
Organocatalyzed Asymmetric Synthesis of Axially, Planar, and Helical Chiral Compounds.
Shirakawa, Seiji; Liu, Shiyao; Kaneko, Shiho
2016-02-04
Axially, planar, and helical chiral compounds are indispensable building blocks in modern organic synthesis. A wide variety of chiral ligands and catalysts were designed based on these chiral scaffolds, and these chiral ligands and catalysts were used for various catalytic asymmetric transformations to produce important chiral compounds in an optically enriched form. Furthermore, these chiral skeletons are found in the structure of biologically active natural products. Thus, the development of efficient enantioselective methods for the synthesis of these chiral compounds is an important task in the field of organic chemistry. In the last few years, organocatalyzed approaches, which are one of the most reliable catalytic asymmetric methods, became a hot topic. This Focus Review summarizes asymmetric organocatalytic methods for the synthesis of axially, planar, and helical chiral compounds as useful chiral building blocks. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
High-concentration planar microtracking photovoltaic system exceeding 30% efficiency
Price, Jared S.; Grede, Alex J.; Wang, Baomin; Lipski, Michael V.; Fisher, Brent; Lee, Kyu-Tae; He, Junwen; Brulo, Gregory S.; Ma, Xiaokun; Burroughs, Scott; Rahn, Christopher D.; Nuzzo, Ralph G.; Rogers, John A.; Giebink, Noel C.
2017-08-01
Prospects for concentrating photovoltaic (CPV) power are growing as the market increasingly values high power conversion efficiency to leverage now-dominant balance of system and soft costs. This trend is particularly acute for rooftop photovoltaic power, where delivering the high efficiency of traditional CPV in the form factor of a standard rooftop photovoltaic panel could be transformative. Here, we demonstrate a fully automated planar microtracking CPV system 660× concentration ratio over a 140∘ full field of view. In outdoor testing over the course of two sunny days, the system operates automatically from sunrise to sunset, outperforming a 17%-efficient commercial silicon solar cell by generating >50% more energy per unit area per day in a direct head-to-head competition. These results support the technical feasibility of planar microtracking CPV to deliver a step change in the efficiency of rooftop solar panels at a commercially relevant concentration ratio.
A 250 GHz planar low noise Schottky receiver
Ali-Ahmad, Walid Y.; Bishop, William L.; Crowe, Thomas W.; Rebeiz, Gabriel M.
1993-01-01
A planar quasi-optical Schottky receiver based on the quasi-integrated horn antenna has been developed and tested over the 230-280 GHz bandwidth. The receiver consists of a planar GaAs Schottky diode placed at the feed of a dipole-probe suspended on a thin dielectric membrane in an etched-pyramidal horn cavity. The diode has a 1.21 micron anode diameter and a low parasitic capacitance due to the use of an etched surface channel. The antenna-mixer results in a measured DSB conversion loss and noise temperature at 258 GHz of 7.2 dB +/- 0.5 dB and 1310 K +/- 70 K, respectively, at room temperature. The design is compatible with SIS mixers, and the low cost of fabrication and simplicity makes it ideal for submillimeter-wave imaging arrays requiring a 10-20 percent bandwidth.
Planar solid oxide fuel cells: the Australian experience and outlook
Godfrey, Bruce; Föger, Karl; Gillespie, Rohan; Bolden, Roger; Badwal, S. P. S.
Since 1992, Ceramic Fuel Cells (CFCL) has grown to what is now the largest focussed program globally for development of planar ceramic (solid oxide) fuel cell, SOFC, technology. A significant intellectual property position in know-how and patents has been developed, with over 80 people involved in the venture. Over $A60 million in funding for the activities of the company has been raised from private companies, government-owned corporations and government business-support programs, including from energy — particularly electricity — industry shareholders that can facilitate access to local markets for our products. CFCL has established state-of-the-art facilities for planar SOFC R&D, with their expansion and scaling-up to pilot manufacturing capability underway. We expect to achieve commercial introduction of our market-entry products in 2002, with prototype systems expected to be available from early 2001.
Perovskite-fullerene hybrid materials suppress hysteresis in planar diodes.
Xu, Jixian
2015-05-08
Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite-PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3(-) antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solar cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour.
Planar-integrated single-crystalline perovskite photodetectors
Saidaminov, Makhsud I.
2015-11-09
Hybrid perovskites are promising semiconductors for optoelectronic applications. However, they suffer from morphological disorder that limits their optoelectronic properties and, ultimately, device performance. Recently, perovskite single crystals have been shown to overcome this problem and exhibit impressive improvements: low trap density, low intrinsic carrier concentration, high mobility, and long diffusion length that outperform perovskite-based thin films. These characteristics make the material ideal for realizing photodetection that is simultaneously fast and sensitive; unfortunately, these macroscopic single crystals cannot be grown on a planar substrate, curtailing their potential for optoelectronic integration. Here we produce large-area planar-integrated films made up of large perovskite single crystals. These crystalline films exhibit mobility and diffusion length comparable with those of single crystals. Using this technique, we produced a high-performance light detector showing high gain (above 104 electrons per photon) and high gain-bandwidth product (above 108 Hz) relative to other perovskite-based optical sensors.
An Electronically Controlled 8-Element Switched Beam Planar Array
Sharawi, Mohammad S.
2015-02-24
An 8-element planar antenna array with electronically controlled switchable-beam pattern is proposed. The planar antenna array consists of patch elements and operates in the 2.45 GHz ISM band. The array is integrated with a digitally controlled feed network that provides the required phases to generate 8 fixed beams covering most of the upper hemisphere of the array. Unlike typical switchable beam antenna arrays, which operate only in one plane, the proposed design is the first to provide full 3D switchable beams with simple control. Only a 3-bit digital word is required for the generation of the 8 different beams. The integrated array is designed on a 3-layer PCB on a Taconic substrate (RF60A). The total dimensions of the fabricated array are 187.1 × 261.3 × 1.3mm^{3}.
Fluorescence based fiber optic and planar waveguide biosensors. A review.
Benito-Peña, Elena; Valdés, Mayra Granda; Glahn-Martínez, Bettina; Moreno-Bondi, Maria C
2016-11-02
The application of optical biosensors, specifically those that use optical fibers and planar waveguides, has escalated throughout the years in many fields, including environmental analysis, food safety and clinical diagnosis. Fluorescence is, without doubt, the most popular transducer signal used in these devices because of its higher selectivity and sensitivity, but most of all due to its wide versatility. This paper focuses on the working principles and configurations of fluorescence-based fiber optic and planar waveguide biosensors and will review biological recognition elements, sensing schemes, as well as some major and recent applications, published in the last ten years. The main goal is to provide the reader a general overview of a field that requires the joint collaboration of researchers of many different areas, including chemistry, physics, biology, engineering, and material science. Copyright © 2016 Elsevier B.V. All rights reserved.
3D NAND Flash Based on Planar Cells
Directory of Open Access Journals (Sweden)
Andrea Silvagni
2017-10-01
Full Text Available In this article, the transition from 2D NAND to 3D NAND is first addressed, and the various 3D NAND architectures are compared. The article carries out a comparison of 3D NAND architectures that are based on a “punch-and-plug” process—with gate-all-around (GAA cell devices—against architectures that are based on planar cell devices. The differences and similarities between the two classes of architectures are highlighted. The differences between architectures using floating-gate (FG and charge-trap (CT devices are also considered. Although the current production of 3D NAND is based on GAA cell devices, it is suggested that architectures with planar cell devices could also be viable for mass production.
Compact cladding-pumped planar waveguide amplifier and fabrication method
Bayramian, Andy J.; Beach, Raymond J.; Honea, Eric; Murray, James E.; Payne, Stephen A.
2003-10-28
A low-cost, high performance cladding-pumped planar waveguide amplifier and fabrication method, for deployment in metro and access networks. The waveguide amplifier has a compact monolithic slab architecture preferably formed by first sandwich bonding an erbium-doped core glass slab between two cladding glass slabs to form a multi-layer planar construction, and then slicing the construction into multiple unit constructions. Using lithographic techniques, a silver stripe is deposited and formed at a top or bottom surface of each unit construction and over a cross section of the bonds. By heating the unit construction in an oven and applying an electric field, the silver stripe is then ion diffused to increase the refractive indices of the core and cladding regions, with the diffusion region of the core forming a single mode waveguide, and the silver diffusion cladding region forming a second larger waveguide amenable to cladding pumping with broad area diodes.
Universal hydrodynamic flow in holographic planar shock collisions
Energy Technology Data Exchange (ETDEWEB)
Chesler, Paul M. [Department of Physics, Harvard University,Cambridge MA 02138 (United States); Kilbertus, Niki [Institut für Theoretische Physik, Universität Regensburg,D-93040 Regensburg (Germany); Schee, Wilke van der [Center for Theoretical Physics, MIT,Cambridge MA 02139 (United States)
2015-11-20
We study the collision of planar shock waves in AdS{sub 5} as a function of shock profile. In the dual field theory the shock waves describe planar sheets of energy whose collision results in the formation of a plasma which behaves hydrodynamically at late times. We find that the post-collision stress tensor near the light cone exhibits transient non-universal behavior which depends on both the shock width and the precise functional form of the shock profile. However, over a large range of shock widths, including those which yield qualitative different behavior near the future light cone, and for different shock profiles, we find universal behavior in the subsequent hydrodynamic evolution. Additionally, we compute the rapidity distribution of produced particles and find it to be well described by a Gaussian.
Recent Techniques in Design and Implementation of Microwave Planar Filters
Directory of Open Access Journals (Sweden)
P. K. Singhal
2008-12-01
Full Text Available This paper details the techniques and initiatives made recently for improved response and simultaneous development of microwave planar filters. Although the objective of all the techniques is to design low cost filters with reduced dimensions, compact size with better frequency response, the methodological approaches are quite variant. The paper has gone through extensive analysis of all these techniques, their concept and design procedures.
Planar Reachability in Linear Space and Constant Time
DEFF Research Database (Denmark)
Holm, Jacob; Rotenberg, Eva; Thorup, Mikkel
2015-01-01
We show how to represent a planar digraph in linear space so that reach ability queries can be answered in constant time. The data structure can be constructed in linear time. This representation of reach ability is thus optimal in both time and space, and has optimal construction time....... The previous best solution used O(n log n) space for constant query time [Thorup FOCS'01]....
Defective planar cell polarity in polycystic kidney disease.
Fischer, Evelyne; Legue, Emilie; Doyen, Antonia; Nato, Faridabano; Nicolas, Jean-François; Torres, Vicente; Yaniv, Moshe; Pontoglio, Marco
2006-01-01
Morphogenesis involves coordinated proliferation, differentiation and spatial distribution of cells. We show that lengthening of renal tubules is associated with mitotic orientation of cells along the tubule axis, demonstrating intrinsic planar cell polarization, and we demonstrate that mitotic orientations are significantly distorted in rodent polycystic kidney models. These results suggest that oriented cell division dictates the maintenance of constant tubule diameter during tubular lengthening and that defects in this process trigger renal tubular enlargement and cyst formation.
Array of planar membrane modules for producing hydrogen
Vencill, Thomas R [Albuquerque, NM; Chellappa, Anand S [Albuquerque, NM; Rathod, Shailendra B [Hillsboro, OR
2012-05-08
A shared or common environment membrane reactor containing a plurality of planar membrane modules with top and bottom thin foil membranes supported by both an intermediary porous support plate and a central base which has both solid extended members and hollow regions or a hollow region whereby the two sides of the base are in fluid communication. The membrane reactor operates at elevate temperatures for generating hydrogen from hydrogen rich feed fuels.
Planar concentrators near the étendue limit.
Winston, Roland; Gordon, Jeffrey M
2005-10-01
Recently proposed aplanatic imaging designs are integrally combined with nonimaging flux boosters to produce an ultracompact planar glass-filled concentrator that performs near the étendue limit. Such optical devices are attractive for high-efficiency multijunction photovoltaics at high flux, with realistic power generation of 1 W from a 1 mm2 cell. When deployed in reverse, our designs provide collimation even for high-numerical-aperture light sources.
Asymmetric Shaped-Pattern Synthesis for Planar Antenna Arrays
Directory of Open Access Journals (Sweden)
T. M. Bruintjes
2016-01-01
Full Text Available A procedure to synthesize asymmetrically shaped beam patterns is developed for planar antenna arrays. As it is based on the quasi-analytical method of collapsed distributions, the main advantage of this procedure is the ability to realize a shaped (null-free region with very low ripple. Smooth and asymmetrically shaped regions can be used for Direction-of-Arrival estimation and subsequently for efficient tracking with a single output (fully analog beamformer.
PLANAR MECHANISMS USED FOR GENERATING CURVE LINE TRANSLATION MOTION
Directory of Open Access Journals (Sweden)
Ovidiu ANTONESCU
2015-05-01
Full Text Available The curve line translation motion can be generated in the particular form of the circular translation, through mono-mobile mechanisms with articulated links of simple parallelogram type (with a fixed side or through transmission with toothed belt with a fixed wheel. Also, the circular translation can be generated through planar mechanisms with two cylindrical gears with a fixed central wheel. It is mentioned that the two cylindrical gearings of the Fergusson mechanisms are both exterior and interior.
The clinical value of planar thallium-201 myocardial perfusion scintigraphy
International Nuclear Information System (INIS)
Niemeyer, M.G.
1989-01-01
The clinical value of planar thalium-201 myocardial perfusion scintigraphy was examined, using visual and quantitative analysis, for the detection of presence, localization and extent of coronary disease, using coronary arteriography as gold standard. The indremental diagnostic yield of different noninvasive tests for the diagnosis and the severity of coronary artery disease was quantified by using multivariate discriminant analysis. (author). 284 refs.; 14 figs.; 37 tabs
Fiber Optic Magnetometers Using Planar And Cylindrical Magnetostrictive Transducers
Bucholtz, F.; Yurek, A. M.; Koo, K. P.; Dandridge, A.
1987-04-01
Fiber optic magnetometers which require high sensitivity at low frequencies (dc-10 Hz) rely on the nonlinear magnetostriction of materials such as amorphous metallic glass alloys. Typically, fiber is bonded to a magnetostrictive sample to convert strain in the sample to phase shift in a fiber interferometer. We present the results of measurements of the frequency dependence and dc and ac magnetic field sensitivity of both planar and cylindrical transducing elements, and discuss the practical advantages and disadvan-tages of each configuration.
Non stochastic distribution of single channels in planar lipid bilayers.
Krasilnikov, O V; Merzliak, P G; Yuldasheva, L N; Nogueira, R A; Rodrigues, C G
1995-02-15
The selectivity of the planar lipid bilayers modified by two channel-forming proteins (alpha-toxin S. aureus and colicin Ia) was examined. It was established that in all cases the value of zero current potential depended on the amount of open ion channels and increased with the number of channels (from one to about 5-7). These facts point out both the interactions among ion channels and their non stochastic distribution on the membrane surface.
Designing large-bandwidth planar photonic crystal waveguides
DEFF Research Database (Denmark)
Lavrinenko, Andrei; Søndergaard, Thomas
2002-01-01
Our waveguide design is characterized by first of all a large bandwidth, and secondly it is characterized by a relatively high group velocity giving a better modal dispersion match with the modes of standard waveguides used for coupling light into the planar crystal waveguide (PCW). We consider t...... the dispersion properties for a PCW based on introducing a line defect in a photonic crystal with air-holes arranged periodically on a triangular lattice in silicon....
Selection of steady states in planar Darcy convection
International Nuclear Information System (INIS)
Tsybulin, V.G.; Karasoezen, B.; Ergenc, T.
2006-01-01
The planar natural convection of an incompressible fluid in a porous medium is considered. We study the selection of steady states under temperature perturbations on the boundary. A selection map is introduced in order to analyze the selection of a steady state from a continuous family of equilibria which exists under zero boundary conditions. The results of finite-difference modeling for a rectangular enclosure are presented
Symmetry and Topology: The 11 Uninodal Planar Nets Revisited
Directory of Open Access Journals (Sweden)
Jean-Guillaume Eon
2018-01-01
Full Text Available A description of the 11 well-known uninodal planar nets is given by Cayley color graphs or alternative Cayley color graphs of plane groups. By applying methods from topological graph theory, the nets are derived from the bouquet B n with rotations mostly as voltages. It thus appears that translation, as a symmetry operation in these nets, is no more fundamental than rotations.
Planar-Structure Perovskite Solar Cells with Efficiency beyond 21.
Jiang, Qi; Chu, Zema; Wang, Pengyang; Yang, Xiaolei; Liu, Heng; Wang, Ye; Yin, Zhigang; Wu, Jinliang; Zhang, Xingwang; You, Jingbi
2017-12-01
Low temperature solution processed planar-structure perovskite solar cells gain great attention recently, while their power conversions are still lower than that of high temperature mesoporous counterpart. Previous reports are mainly focused on perovskite morphology control and interface engineering to improve performance. Here, this study systematically investigates the effect of precise stoichiometry, especially the PbI 2 contents on device performance including efficiency, hysteresis and stability. This study finds that a moderate residual of PbI 2 can deliver stable and high efficiency of solar cells without hysteresis, while too much residual PbI 2 will lead to serious hysteresis and poor transit stability. Solar cells with the efficiencies of 21.6% in small size (0.0737 cm 2 ) and 20.1% in large size (1 cm 2 ) with moderate residual PbI 2 in perovskite layer are obtained. The certificated efficiency for small size shows the efficiency of 20.9%, which is the highest efficiency ever recorded in planar-structure perovskite solar cells, showing the planar-structure perovskite solar cells are very promising. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
SOI waveguide based planar reflective grating demultiplexer for FTTH
Bidnyk, S.; Feng, D.; Balakrishnan, A.; Pearson, M.; Gao, M.; Liang, H.; Qian, W.; Kung, C.-C.; Fong, J.; Yin, J.; Asghari, M.
2007-02-01
Recent deployments of fiber-to-the-home (FTTH) represent the fastest growing sector of the telecommunication industry. The emergence of the silicon-on-insulator (SOI) photonics presents an opportunity to exploit the wide availability of silicon foundries and high-quality low-cost substrates for addressing the FTTH market. We have now demonstrated that a monolithically integrated FTTH demultiplexer can be built using the SOI platform. The SOI filter comprises a monolithically integrated planar reflective grating and a multi-stage Mach-Zehnder interferometer that were fabricated using a CMOS-compatible SOI process with the core thickness of 3.0 μm and optically insulating layer of silica with a thickness of 0.375 μm. The Mach-Zehnder interferometer was used to coarsely separate the 1310 nm channel from 1490 and 1550 nm channels. Subsequently, a planar reflective grating was used to demultiplex the 1490 and 1550 nm channels. The manufactured device showed the 1-dB bandwidth of 110 nm for the 1310 nm channel. For the 1490 nm and 1550 nm channels, the 1-dB bandwidth was measured to be 30 nm. The adjacent channel isolation between the 1490 nm and 1550 nm channels was better than 32 dB. The optical isolation between the 1310 nm and 1490 and 1550 nm channels was better than 45 dB. Applications of the planar reflective gratings in the FTTH networks are discussed.
The Prohibitive Link between Position-based Routing and Planarity
Directory of Open Access Journals (Sweden)
David Cairns
2013-12-01
Full Text Available Position-based routing is touted as an ideal routing strategy for resource-constrained wireless networks. One persistent barrier to adoption is due to its recovery phase, where messages are forwarded according to leftor right-hand rule (LHR. This is often referred to as face-routing. In this paper we investigate the limits of LHR with respect to planarity.We show that the gap between non-planarity and successful delivery is a single link within a single configuration. Our work begins with an analysis to enumerate all node configurations that cause intersections in the unit-disc graph. We find that left-hand rule is able to recover from all but a single case, the ‘umbrella’ configuration so named for its appearance. We use this information to propose the Prohibitive Link Detection Protocol (PLDP that can guarantee delivery over non-planar graphs using standard face-routing techniques. As the name implies, the protocol detects and circumvents the ‘bad’ links that hamper LHR. The goal of this work is to maintain routing guarantees while disturbing the network graph as little as possible. In doing so, a new starting point emerges from which to build rich distributed protocols in the spirit of CLDP and GDSTR.
Load estimation from planar PIV measurement in vortex dominated flows
McClure, Jeffrey; Yarusevych, Serhiy
2017-11-01
Control volume-based loading estimates are employed on experimental and synthetic numerical planar Particle Image Velocimetry (PIV) data of a stationary cylinder and a cylinder undergoing one degree-of-freedom (1DOF) Vortex Induced Vibration (VIV). The results reveal the necessity of including out of plane terms, identified from a general formulation of the control volume momentum balance, when evaluating loads from planar measurements in three-dimensional flows. Reynolds stresses from out of plane fluctuations are shown to be significant for both instantaneous and mean force estimates when the control volume encompasses vortex dominated regions. For planar measurement, invoking a divergence-free assumption allows accurate estimation of half the identified terms. Towards evaluating the fidelity of PIV-based loading estimates for obtaining the forcing function unobtrusively in VIV experiments, the accuracy of the control volume-based loading methodology is evaluated using the numerical data with synthetically generated experimental PIV error, and a comparison is made between experimental PIV-based estimates and simultaneous force balance measurements.
Model Correction Factor Method
DEFF Research Database (Denmark)
Christensen, Claus; Randrup-Thomsen, Søren; Morsing Johannesen, Johannes
1997-01-01
The model correction factor method is proposed as an alternative to traditional polynomial based response surface techniques in structural reliability considering a computationally time consuming limit state procedure as a 'black box'. The class of polynomial functions is replaced by a limit...... statebased on an idealized mechanical model to be adapted to the original limit state by the model correction factor. Reliable approximations are obtained by iterative use of gradient information on the original limit state function analogously to previous response surface approaches. However, the strength...... of the model correction factor method, is that in simpler form not using gradient information on the original limit state function or only using this information once, a drastic reduction of the number of limit state evaluation is obtained together with good approximations on the reliability. Methods...
International Nuclear Information System (INIS)
Tejera R, A.; Cortes P, A.; Becerril V, A.
1990-03-01
For the practical application of the method proposed by J. Bryant, the authors carried out a series of small corrections, related with the bottom, the dead time of the detectors and channels, with the resolution time of the coincidences, with the accidental coincidences, with the decay scheme and with the gamma efficiency of the beta detector beta and the beta efficiency beta of the gamma detector. The calculation of the correction formula is presented in the development of the present report, being presented 25 combinations of the probability of the first existent state at once of one disintegration and the second state at once of the following disintegration. (Author)
Multiview Trajectory Mapping Using Homography with Lens Distortion Correction
Directory of Open Access Journals (Sweden)
Andrea Cavallaro
2008-11-01
Full Text Available We present a trajectory mapping algorithm for a distributed camera setting that is based on statistical homography estimation accounting for the distortion introduced by camera lenses. Unlike traditional approaches based on the direct linear transformation (DLT algorithm and singular value decomposition (SVD, the planar homography estimation is derived from renormalization. In addition to this, the algorithm explicitly introduces a correction parameter to account for the nonlinear radial lens distortion, thus improving the accuracy of the transformation. We demonstrate the proposed algorithm by generating mosaics of the observed scenes and by registering the spatial locations of moving objects (trajectories from multiple cameras on the mosaics. Moreover, we objectively compare the transformed trajectories with those obtained by SVD and least mean square (LMS methods on standard datasets and demonstrate the advantages of the renormalization and the lens distortion correction.
Multiview Trajectory Mapping Using Homography with Lens Distortion Correction
Directory of Open Access Journals (Sweden)
Kayumbi Gabin
2008-01-01
Full Text Available Abstract We present a trajectory mapping algorithm for a distributed camera setting that is based on statistical homography estimation accounting for the distortion introduced by camera lenses. Unlike traditional approaches based on the direct linear transformation (DLT algorithm and singular value decomposition (SVD, the planar homography estimation is derived from renormalization. In addition to this, the algorithm explicitly introduces a correction parameter to account for the nonlinear radial lens distortion, thus improving the accuracy of the transformation. We demonstrate the proposed algorithm by generating mosaics of the observed scenes and by registering the spatial locations of moving objects (trajectories from multiple cameras on the mosaics. Moreover, we objectively compare the transformed trajectories with those obtained by SVD and least mean square (LMS methods on standard datasets and demonstrate the advantages of the renormalization and the lens distortion correction.
Lin, Mu-Han; Veltchev, Iavor; Koren, Sion; Ma, Charlie; Li, Jinsgeng
2015-07-08
Robotic radiosurgery system has been increasingly employed for extracranial treatments. This work is aimed to study the feasibility of a cylindrical diode array and a planar ion chamber array for patient-specific QA with this robotic radiosurgery system and compare their performance. Fiducial markers were implanted in both systems to enable image-based setup. An in-house program was developed to postprocess the movie file of the measurements and apply the beam-by-beam angular corrections for both systems. The impact of noncoplanar delivery was then assessed by evaluating the angles created by the incident beams with respect to the two detector arrangements and cross-comparing the planned dose distribution to the measured ones with/without the angular corrections. The sensitivity of detecting the translational (1-3 mm) and the rotational (1°-3°) delivery errors were also evaluated for both systems. Six extracranial patient plans (PTV 7-137 cm³) were measured with these two systems and compared with the calculated doses. The plan dose distributions were calculated with ray-tracing and the Monte Carlo (MC) method, respectively. With 0.8 by 0.8 mm² diodes, the output factors measured with the cylindrical diode array agree better with the commissioning data. The maximum angular correction for a given beam is 8.2% for the planar ion chamber array and 2.4% for the cylindrical diode array. The two systems demonstrate a comparable sensitivity of detecting the translational targeting errors, while the cylindrical diode array is more sensitive to the rotational targeting error. The MC method is necessary for dose calculations in the cylindrical diode array phantom because the ray-tracing algorithm fails to handle the high-Z diodes and the acrylic phantom. For all the patient plans, the cylindrical diode array/ planar ion chamber array demonstrate 100% / > 92% (3%/3 mm) and > 96% / ~ 80% (2%/2 mm) passing rates. The feasibility of using both systems for robotic
Error Correcting Codes -34 ...
Indian Academy of Sciences (India)
Science, Bangalore. Her interests are in. Theoretical Computer. Science. SERIES I ARTICLE. Error Correcting Codes. 2. The Hamming Codes. Priti Shankar. In the first article of this series we showed how redundancy introduced into a message transmitted over a noisy channel could improve the reliability of transmission. In.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 3. Error Correcting Codes - Reed Solomon Codes. Priti Shankar. Series Article Volume 2 Issue 3 March 1997 pp 33-47. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/03/0033-0047 ...
Indian Academy of Sciences (India)
focused pictures of Triton, Neptune's largest moon. This great feat was in no small measure due to the fact that the sophisticated communication system on Voyager had an elaborate error correcting scheme built into it. At Jupiter and Saturn, a convolutional code was used to enhance the reliability of transmission, and at ...
Full Text Available ... their surgery, orthognathic surgery is performed to correct functional problems. Jaw Surgery can have a dramatic effect on many aspects of life. Following are some of the conditions that may ... front, or side Facial injury Birth defects Receding lower jaw and ...
Full Text Available ... It can also invite bacteria that lead to gum disease. Click here to find out more. Who We Are Find a Surgeon News Videos Contact Anesthesia Cleft Lip/Palate and Craniofacial Surgery Corrective Jaw Surgery Dental Implant Surgery Extractions and Other Oral Surgeries Facial Cosmetic ...
Correctness of concurrent processes
E.R. Olderog (Ernst-Rüdiger)
1989-01-01
textabstractA new notion of correctness for concurrent processes is introduced and investigated. It is a relationship P sat S between process terms P built up from operators of CCS [Mi 80], CSP [Ho 85] and COSY [LTS 79] and logical formulas S specifying sets of finite communication sequences as in
Indian Academy of Sciences (India)
It was engineering on the grand scale. - the use of new material for .... ROAD REPAIRSCE!STOP}!TL.,ZBFALK where errors occur in both the message as well as the check symbols, the decoder would be able to correct all of these (as there are not more than 8 .... before it is conveyed to the master disc. Modulation caters for.
Text Induced Spelling Correction
Reynaert, M.W.C.
2004-01-01
We present TISC, a language-independent and context-sensitive spelling checking and correction system designed to facilitate the automatic removal of non-word spelling errors in large corpora. Its lexicon is derived from a very large corpus of raw text, without supervision, and contains word
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 3. Error Correcting Codes - Reed Solomon Codes. Priti Shankar. Series Article Volume 2 Issue 3 March ... Author Affiliations. Priti Shankar1. Department of Computer Science and Automation, Indian Institute of Science, Bangalore 560 012, India ...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 4. Algorithms - Correctness of Programs. R K Shyamasundar. Series Article Volume 3 ... Author Affiliations. R K Shyamasundar1. Computer Science Group, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India.
Correctional Practices in Japan.
Eskridge, Chris W.
1989-01-01
Describes Japanese correctional system including its early history and adoption of Western ideas in the late nineteenth century. Presents current Japanese treatment practices, probation/parole systems, and other offender assistance programs pointing out the importance of individual responsibility and community involvement to the system. Compares…
Issues in Correctional Training and Casework. Correctional Monograph.
Wolford, Bruce I., Ed.; Lawrenz, Pam, Ed.
The eight papers contained in this monograph were drawn from two national meetings on correctional training and casework. Titles and authors are: "The Challenge of Professionalism in Correctional Training" (Michael J. Gilbert); "A New Perspective in Correctional Training" (Jack Lewis); "Reasonable Expectations in Correctional Officer Training:…
Including gauge corrections to thermal leptogenesis
International Nuclear Information System (INIS)
Huetig, Janine
2013-01-01
. Furthermore, we have computed the Majorana neutrino production rate itself in chapter 6 to test our numerical procedure. In this context we have calculated the tree-level result as well as the gauge corrected result for the Majorana neutrino production rate. Finally in chapter 7, we have implemented the Majorana neutrino ladder rung diagram into our setup for leptogenesis: As a first consideration, we have collected all gauge corrected diagrams up to three-loop order for the asymmetry-causing two-loop diagrams. However, the results of chap. 5 showed that it is not sufficient to just include diagrams up to three-loop level. Due to the necessity of resumming all n-loop diagrams, we have constructed a cylindrical diagram that fulfils this condition. This diagram is the link between the Majorana neutrino ladder rung diagram calculated before on the one hand and the lepton asymmetry on the other. Therefore we have been able to derive a complete expression for the integrated lepton number matrix including all leading order corrections. The numerical analysis of this lepton number matrix needs a great computational effort since for the resulting eight-dimensional integral two ordinary differential equations have to be computed for each point the routine evaluates. Thus the result remains yet inaccessible. Research perspectives: Summarising, this thesis provides the basis for a systematic inclusion of gauge interactions in thermal leptogenesis scenarios. As a next step, one should evaluate the expression for the integrated lepton number numerically to gain a value, which can be used for comparison to earlier results such as the solutions of the Boltzmann equations as well as the Kadanoff-Baym ansatz with the implemented Standard Model widths. This numerical result would be the first quantitative number, which contains leading order corrections due to all interactions of the Majorana neutrino with the Standard Model particles. Further corrections by means of including washout effects
Rotenberg, David; Chiew, Mark; Ranieri, Shawn; Tam, Fred; Chopra, Rajiv; Graham, Simon J
2013-03-01
Head motion artifacts are a major problem in functional MRI that limit its use in neuroscience research and clinical settings. Real-time scan-plane correction by optical tracking has been shown to correct slice misalignment and nonlinear spin-history artifacts; however, residual artifacts due to dynamic magnetic field nonuniformity may remain in the data. A recently developed correction technique, Phase Labeling for Additional Coordinate Encoding, can correct for absolute geometric distortion using only the complex image data from two echo planar images with slightly shifted k-space trajectories. An approach is presented that integrates Phase Labeling for Additional Coordinate Encoding into a real-time scan-plane update system by optical tracking, applied to a tissue-equivalent phantom undergoing complex motion and an functional MRI finger tapping experiment with overt head motion to induce dynamic field nonuniformity. Experiments suggest that such integrated volume-by-volume corrections are very effective at artifact suppression, with potential to expand functional MRI applications. Copyright © 2012 Wiley Periodicals, Inc.
Study on durability for thermal cycle of planar SOFC
Energy Technology Data Exchange (ETDEWEB)
Ando, Motoo; Nakata, Kei-ichi; Wakayama, Sin-ichi [Tonen Corp., Saitama (Japan)] [and others
1996-12-31
TONEN CORPORATION has developed planar type SOFC since 1986. We demonstrated the output of 1.3 kW in 1991 and 5.1 kW in 1995. Simultaneously we have studied how to raise electric efficiency and reliability utilizing hydrogen and propane as fuel. Durability for thermal cycle is one of the most important problems of planar SOFC to make it more practical. The planar type SOFC is made up of separator, zirconia electrolyte and glass sealant. The thermal expansion of these components are expected to be the same value, however, they still possess small differences. In this situation, a thermal cycle causes a thermal stress due to the difference of the cell components and is often followed by a rupture in cell components, therefore, the analysis of the thermal stress should give us much useful information. The thermal cycle process consists of a heating up and cooling down procedure. Zirconia electrolyte is not bonded to the separator under the condition of the initial heating up procedure, and glass sealant becomes soft or melts and glass seals spaces between the zirconia and separator. The glass sealant becomes harder with the cooling down procedure. Moreover, zirconia is tightly bonded with separator below a temperature which is defined as a constraint temperature and thermal stress also occurs. This indicates that the heating up process relaxes the thermal stress and the cooling down increases it. In this paper, we simulated dependence of the stress on the sealing configuration, thermal expansion of sealant and constraint temperature of sealant glass. Furthermore, we presented SOFC electrical properties after a thermal cycle.
Discretisation Schemes for Level Sets of Planar Gaussian Fields
Beliaev, D.; Muirhead, S.
2018-01-01
Smooth random Gaussian functions play an important role in mathematical physics, a main example being the random plane wave model conjectured by Berry to give a universal description of high-energy eigenfunctions of the Laplacian on generic compact manifolds. Our work is motivated by questions about the geometry of such random functions, in particular relating to the structure of their nodal and level sets. We study four discretisation schemes that extract information about level sets of planar Gaussian fields. Each scheme recovers information up to a different level of precision, and each requires a maximum mesh-size in order to be valid with high probability. The first two schemes are generalisations and enhancements of similar schemes that have appeared in the literature (Beffara and Gayet in Publ Math IHES, 2017. https://doi.org/10.1007/s10240-017-0093-0; Mischaikow and Wanner in Ann Appl Probab 17:980-1018, 2007); these give complete topological information about the level sets on either a local or global scale. As an application, we improve the results in Beffara and Gayet (2017) on Russo-Seymour-Welsh estimates for the nodal set of positively-correlated planar Gaussian fields. The third and fourth schemes are, to the best of our knowledge, completely new. The third scheme is specific to the nodal set of the random plane wave, and provides global topological information about the nodal set up to `visible ambiguities'. The fourth scheme gives a way to approximate the mean number of excursion domains of planar Gaussian fields.
In vivo quantification of 177Lu with planar whole-body and SPECT/CT gamma camera imaging
International Nuclear Information System (INIS)
Bailey, Dale L.; Hennessy, Thomas M.; Willowson, Kathy P.; Henry, E. Courtney; Chan, David L.H.; Aslani, Alireza; Roach, Paul J.
2015-01-01
Advances in gamma camera technology and the emergence of a number of new theranostic radiopharmaceutical pairings have re-awakened interest in in vivo quantification with single-photon-emitting radionuclides. We have implemented and validated methodology to provide quantitative imaging of 177 Lu for 2D whole-body planar studies and for 3D tomographic imaging with single-photon emission computed tomography (SPECT)/CT. Whole-body planar scans were performed on subjects to whom a known amount of [ 177 Lu]-DOTA-octreotate had been administered for therapy. The total radioactivity estimated from the images was compared with the known amount of the radionuclide therapy administered. In separate studies, venous blood samples were withdrawn from subjects after administration of [ 177 Lu]-DOTA-octreotate while a SPECT acquisition was in progress and the concentration of the radionuclide in the venous blood sample compared with that estimated from large blood pool structures in the SPECT reconstruction. The total radioactivity contained within an internal SPECT calibration standard was also assessed. In the whole-body planar scans (n = 28), the estimated total body radioactivity was accurate to within +4.6 ± 5.9 % (range −17.1 to +11.2 %) of the correct value. In the SPECT reconstructions (n = 12), the radioactivity concentration in the cardiac blood pool was accurate to within −4.0 ± 7.8 % (range −16.1 to +7.5 %) of the true value and the internal standard measurements (n = 89) were within 2.0 ± 8.5 % (range −16.3 to +24.2 %) of the known amount of radioactivity contained. In our hands, state-of-the-art hybrid SPECT/CT gamma cameras were able to provide accurate estimates of in vivo radioactivity to better than, on average, ±10 % for use in biodistribution and radionuclide dosimetry calculations.
In vivo quantification of {sup 177}Lu with planar whole-body and SPECT/CT gamma camera imaging
Energy Technology Data Exchange (ETDEWEB)
Bailey, Dale L. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Faculty of Health Sciences, University of Sydney, Cumberland, NSW (Australia); Sydney Medical School, University of Sydney, Camperdown, NSW (Australia); NETwork, Sydney Vital, St Leonards, Sydney, NSW (Australia); Hennessy, Thomas M.; Willowson, Kathy P.; Henry, E. Courtney [Institute of Medical Physics, University of Sydney, Camperdown, NSW (Australia); Chan, David L.H. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); NETwork, Sydney Vital, St Leonards, Sydney, NSW (Australia); Aslani, Alireza [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Roach, Paul J. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Sydney Medical School, University of Sydney, Camperdown, NSW (Australia)
2015-09-17
Advances in gamma camera technology and the emergence of a number of new theranostic radiopharmaceutical pairings have re-awakened interest in in vivo quantification with single-photon-emitting radionuclides. We have implemented and validated methodology to provide quantitative imaging of {sup 177}Lu for 2D whole-body planar studies and for 3D tomographic imaging with single-photon emission computed tomography (SPECT)/CT. Whole-body planar scans were performed on subjects to whom a known amount of [{sup 177}Lu]-DOTA-octreotate had been administered for therapy. The total radioactivity estimated from the images was compared with the known amount of the radionuclide therapy administered. In separate studies, venous blood samples were withdrawn from subjects after administration of [{sup 177}Lu]-DOTA-octreotate while a SPECT acquisition was in progress and the concentration of the radionuclide in the venous blood sample compared with that estimated from large blood pool structures in the SPECT reconstruction. The total radioactivity contained within an internal SPECT calibration standard was also assessed. In the whole-body planar scans (n = 28), the estimated total body radioactivity was accurate to within +4.6 ± 5.9 % (range −17.1 to +11.2 %) of the correct value. In the SPECT reconstructions (n = 12), the radioactivity concentration in the cardiac blood pool was accurate to within −4.0 ± 7.8 % (range −16.1 to +7.5 %) of the true value and the internal standard measurements (n = 89) were within 2.0 ± 8.5 % (range −16.3 to +24.2 %) of the known amount of radioactivity contained. In our hands, state-of-the-art hybrid SPECT/CT gamma cameras were able to provide accurate estimates of in vivo radioactivity to better than, on average, ±10 % for use in biodistribution and radionuclide dosimetry calculations.
Students' Attitude toward Correction
Rinda Fitriana
2017-01-01
Students’ attitudes influence their decision to whether or not accept the teachers’ feedback. Therefore, questionnaire was administered to one hundred and ninety-six twelfth grade of vocational high school students, wherein, ten of them were involved in interview, to figure out their perspective concerning to the teachers’ correction on their oral production. From both instruments, it is found that the students preferred the teachers as the correctors, although, they did not mind for peer cor...
Akoensi, Thomas D
2017-01-01
Corrections in Ghana has evolved from communal traditional practices emphasizing offender reintegration and restitution to offender punishment in prisons. Prisons in Ghana represent a colonial legacy and its modus operandi via the maintenance of safe custody, and welfare provision since independence remains unchanged. The raison d'être of prison administration is security and discipline, with little emphasis and resource provision geared toward offender rehabilitation. With no parole system o...
[Correct contact lens hygiene].
Blümle, S; Kaercher, T; Khaireddin, R
2013-06-01
Although contact lenses have long been established in ophthalmology, practical aspects of handling contact lenses is becoming increasingly less important in the clinical training as specialist for ophthalmology. Simultaneously, for many reasons injuries due to wearing contact lenses are increasing. In order to correct this discrepancy, information on contact lenses and practical experience with them must be substantially increased from a medical perspective. This review article deals with the most important aspects for prevention of complications, i.e. contact lens hygiene.
Congenitally corrected transposition
Directory of Open Access Journals (Sweden)
Debich-Spicer Diane
2011-05-01
Full Text Available Abstract Congenitally corrected transposition is a rare cardiac malformation characterized by the combination of discordant atrioventricular and ventriculo-arterial connections, usually accompanied by other cardiovascular malformations. Incidence has been reported to be around 1/33,000 live births, accounting for approximately 0.05% of congenital heart malformations. Associated malformations may include interventricular communications, obstructions of the outlet from the morphologically left ventricle, and anomalies of the tricuspid valve. The clinical picture and age of onset depend on the associated malformations, with bradycardia, a single loud second heart sound and a heart murmur being the most common manifestations. In the rare cases where there are no associated malformations, congenitally corrected transposition can lead to progressive atrioventricular valvar regurgitation and failure of the systemic ventricle. The diagnosis can also be made late in life when the patient presents with complete heart block or cardiac failure. The etiology of congenitally corrected transposition is currently unknown, and with an increase in incidence among families with previous cases of congenitally corrected transposition reported. Diagnosis can be made by fetal echocardiography, but is more commonly made postnatally with a combination of clinical signs and echocardiography. The anatomical delineation can be further assessed by magnetic resonance imaging and catheterization. The differential diagnosis is centred on the assessing if the patient is presenting with isolated malformations, or as part of a spectrum. Surgical management consists of repair of the associated malformations, or redirection of the systemic and pulmonary venous return associated with an arterial switch procedure, the so-called double switch approach. Prognosis is defined by the associated malformations, and on the timing and approach to palliative surgical care.
Leakage Inductance Calculation for Planar Transformers with a Magnetic Shunt
DEFF Research Database (Denmark)
Jun, Zhang; Ouyang, Ziwei; Duffy, M. C.
2013-01-01
The magnetic shunt is generally inserted in a planar transformer to increase the leakage inductance which can be utilized as the series inductor in resonant circuits such as the LLC resonant converter. This paper presents a calculation methodology for the leakage inductance of the transformer...... with a magnetic shunt by means of the stored magnetic energy in the primary and secondary sides of the transformer using the magnetomotive force (MMF) variation method, as well as the stored energy in the shunt based on the reluctance model. The detailed calculation method is described. Both the FEA simulation...
Leakage Inductance Calculation for Planar Transformers with a Magnetic Shunt
DEFF Research Database (Denmark)
Zhang, Jun; Ouyang, Ziwei; Duffy, Maeve C.
2014-01-01
The magnetic shunt is generally inserted in a planar transformer to increase the leakage inductance which can be utilized as the series inductor in resonant circuits such as the LLC resonant converter. This paper presents a calculation methodology for the leakage inductance of the transformer...... with a magnetic shunt by means of the stored magnetic energy in the primary and secondary sides of the transformer using the magnetomotive force (MMF) variation method, as well as the stored energy in the shunt based on the reluctance model. The detailed calculation method is described. Both the FEA simulation...
Interpreting biomagnetic fields of planar wave fronts in cardiac muscle.
dos Santos, Rodrigo Weber; Koch, Hans
2005-05-01
The recent results of Holzer and co-workers reveal the existence of net currents that flow along the front of a planar wave propagating through cardiac tissue. This is an important contribution toward the better understanding of the physics of biomagnetic fields. However, although the authors claim their results reveal particular bidomain properties, we show in this short letter that the results allow multiple interpretations. For instance, cardiac anisotropy by itself may also explain the existence of a net current along the wave front. Based on our calculations, we suggest additional experiments that would allow distinguishing between these two explanations and thus provide further evidence on the basic physics behind cardiac biomagnetism.
The effective compliance of spatially evolving planar wing-cracks
Ayyagari, R. S.; Daphalapurkar, N. P.; Ramesh, K. T.
2018-02-01
We present an analytic closed form solution for anisotropic change in compliance due to the spatial evolution of planar wing-cracks in a material subjected to largely compressive loading. A fully three-dimensional anisotropic compliance tensor is defined and evaluated considering the wing-crack mechanism, using a mixed-approach based on kinematic and energetic arguments to derive the coefficients in incremental compliance. Material, kinematic and kinetic parametric influences on the increments in compliance are studied in order to understand their physical implications on material failure. Model verification is carried out through comparisons to experimental uniaxial compression results to showcase the predictive capabilities of the current study.
Anfo Response To Low-Stress Planar Impacts
Cooper, Marcia A.; Trott, Wayne M.; Schmitt, Robert G.; Short, Mark; Jackson, Scott I.
2012-03-01
Ammonium Nitrate plus Fuel Oil (ANFO) is a non-ideal explosive where the mixing behavior of the mm-diameter prills with the absorbed fuel oil is of critical importance for chemical energy release. The large-scale heterogeneity of ANFO establishes conditions uniquely suited for observation using the spatially- and temporally-resolved line-imaging ORVIS (Optically Recording Velocity Interferometer System) diagnostic. The first demonstration of transmitted wave profiles in ANFO from planar impacts using a single-stage gas gun is reported. Major observations including an extended compaction precursor, post-shock particle velocity variations and between-prill jetting are reported.
Giant optical forces in planar dielectric photonic metamaterials.
Zhang, Jianfa; MacDonald, Kevin F; Zheludev, Nikolay I
2014-08-15
We demonstrate that resonant optical forces generated within all-dielectric planar photonic metamaterials at near-infrared illumination wavelengths can be an order of magnitude larger than in corresponding plasmonic metamaterials, reaching levels many tens of times greater than the force resulting from radiation pressure. This is made possible by the dielectric structures' freedom from Joule losses and the consequent ability to sustain Fano-resonances with high quality factors that are unachievable in plasmonic nanostructures. Dielectric nano-optomechanical metamaterials can thus provide a functional platform for a range of novel dynamically controlled and self-adaptive nonlinear, tunable/switchable photonic metamaterials.
GE NANOCLUSTERS IN PLANAR GLASS WAVEGUIDES DEPOSITED BY PECVD
DEFF Research Database (Denmark)
Haiyan, Ou; Olsen, Johnny H.; Rottwitt, Karsten
2004-01-01
. In this work we study the size and distribution of the nanoclusters by transmission electron microscopy (TEM) and Raman spectroscopy. The formation of the clusters is investigated by varying the Ge concentration in the glass and changing the annealing conditions such as temperature, atmosphere and time....... The combined effect of a strong nonlinear glass material and a material platform that is well known from standard planar lightwave components makes this Ge nanoclusters material very promising for optical nonlinear waveguide components that are readily fabricated by using the same processing as standard...
A planar Mie scattering technique for visualizing supersonic mixing flows
Clemens, N. T.; Mungal, M. G.
1991-01-01
A planar Mie scattering technique is described which allows for the direct visualization of fluid mixing in supersonic flows. The mixed fluid is visualized by laser light sheet scattering from small alcohol droplets which condense as a result of the mixing of a vapor laden subsonic stream with a cold supersonic stream. Issues related to the formation, growth and size of the droplets are addressed. The technique reveals details of the turbulent structure which are masked by the spatial integration of schlieren and shadowgraph methods. Comparative visualizations using the vapor screen method to uniformly mark the high-speed fluid are also shown.
Modal Analysis of MARS Solar Panel and Planar Vibrations
Simonyan, Andranik; Williams, R. Brett
2007-01-01
This slide presentation reviews the modal analysis of MARS solar panels and the planar vibrations. Included are views of the solar panels mock-up assembly, a view of the test seup,a view of the plot from the test, with the raw numbers of the frequencies in Hz values with the mode number, the spatial acceleration plots of Center sub panel at resonant frequencies, predictions from the Finite element models, an explanation of the two test that were done on the plate and the results from both tests,
Simple Planar Truss (Linear, Nonlinear and Stochastic Approach
Directory of Open Access Journals (Sweden)
Frydrýšek Karel
2016-11-01
Full Text Available This article deals with a simple planar and statically determinate pin-connected truss. It demonstrates the processes and methods of derivations and solutions according to 1st and 2nd order theories. The article applies linear and nonlinear approaches and their simplifications via a Maclaurin series. Programming connected with the stochastic Simulation-Based Reliability Method (i.e. the direct Monte Carlo approach is used to conduct a probabilistic reliability assessment (i.e. a calculation of the probability that plastic deformation will occur in members of the truss.
Planar pentacoordinate carbon atoms embedded in a metallocene framework.
Cui, Zhong-Hua; Vassilev-Galindo, Valentin; Luis Cabellos, José; Osorio, Edison; Orozco, Mesías; Pan, Sudip; Ding, Yi-Hong; Merino, Gabriel
2016-12-20
Viable planar pentacoordinate carbon (ppC) systems with a ppC bonded to a transition metal and embedded in a metallocene framework are reported. Our detailed global minima search shows that CAl 4 MX 2 (M = Zr and Hf; X = F-I and C 5 H 5 ) clusters with ppCs are appropriate candidates for experimental realization in the gas phase. The fulfillment of the 18 electron rule and electron delocalization is found to be crucial for the stabilization of these ppC arrangements.
A fuzzy clustering algorithm to detect planar and quadric shapes
Krishnapuram, Raghu; Frigui, Hichem; Nasraoui, Olfa
1992-01-01
In this paper, we introduce a new fuzzy clustering algorithm to detect an unknown number of planar and quadric shapes in noisy data. The proposed algorithm is computationally and implementationally simple, and it overcomes many of the drawbacks of the existing algorithms that have been proposed for similar tasks. Since the clustering is performed in the original image space, and since no features need to be computed, this approach is particularly suited for sparse data. The algorithm may also be used in pattern recognition applications.
THz plasmonic modes in metal-clad planar multilayer waveguides
Ghamsari, Behnood G.; Majedi, A. Hamed
2009-05-01
This paper studies the role of plasmonic modes for guided-wave propagation of THz/far infrared in metalclad planar waveguides, including metal-dielectric interfaces, dielectric-loaded metal slabs and parallel plate waveguides. The dispersion of modal characteristics of the plasmonic guided waves, such as the effective index, attenuation constant and the field confinement, as a function of geometrical features for different consisting materials and wavelengths are examined. Moreover, comparison is made between the THz plasmonic modes to their optical counterparts at visible/near infrared within the similar physical structures. Peculiar features of each structure are highlighted and regimes of interest are distinguished.
A planar parallel 3-DOF cable-driven haptic interface
Directory of Open Access Journals (Sweden)
Régis Poulin
2009-06-01
Full Text Available In this paper, a cable-driven planar parallel haptic interface is pre- sented. First, the velocity equations are derived and the forces in the cables are obtained by the principle of virtual work. Then, an analysis of the wrench-closure workspace is performed and a ge- ometric arrangement of the cables is proposed. Control issues are then discussed and a control scheme is presented. The calibration of the attachment points is also discussed. Finally, the prototype is described and experimental results are provided.
Progress in the planar CPn SOFC system design verification
Energy Technology Data Exchange (ETDEWEB)
Elangovan, S.; Hartvigsen, J.; Khandkar, A. [SOFCo, Salt Lake City, UT (United States)
1996-04-01
SOFCo is developing a high efficiency, modular and scaleable planar SOFC module termed the CPn design. This design has been verified in a 1.4 kW module test operated directly on pipeline natural gas. The design features multistage oxidation of fuel wherein the fuel is consumed incrementally over several stages. High efficiency is achieved by uniform current density distribution per stage, which lowers the stack resistance. Additional benefits include thermal regulation and compactness. Test results from stack modules operating in pipeline natural gas are presented.
Planar quadrature coil design using shielded-loop resonators
DEFF Research Database (Denmark)
Stensgaard, A
1997-01-01
The shielded-loop resonator is known to have a low capacitive sample loss due to a perfect balancing. In this paper, it is demonstrated that shielded-loop technology also can be used to improve design of planar quadrature coils. Both a dual-loop circuit and especially a dual-mode circuit may...... benefit from use of shielded-loop resonators. Observations in measurements agree with theory for both a dual-loop coil and a dual-mode coil. The coils were designed for use as transmit/receive coil for 1H imaging and spectroscopy at 4.7 T in rat brain....
Planar optical waveguides for civil and military applications
International Nuclear Information System (INIS)
Lavers, C R
2009-01-01
There is significant military and civil interest in being able to detect chemical species adsorbed from air or present in aqueous solutions. Planar optical waveguide transmission properties are sensitive to changes in parameters such as refractive index or absorption and to light-emitting processes such as fluorescence. These changes modulate light travelling in optical waveguides, and so may be used as sensors for detecting biological and chemical agents, non-ionizing and ionizing electromagnetic radiation. Several waveguide systems have been studied theoretically and experimentally, and their responses to basic influences such as alcohol and UV radiation, and gamma rays determined.
A study of coFeB magnetic yoke based on planar electromagnet
Qin, L.; Li, Q.; Yuan, Yong J.
2017-07-01
This paper studies the fabrication of a novel planar electromagnet consisting of a planar copper coil and a magnetic yoke. CoFeB was used as the magnetic yoke material instead of the traditional permanent magnets. The planar electromagnet was fabricated and optimized to maximize the electromagnetic force, especially with varying CoFeB thickness. The micro-planar electromagnet was fabricated successfully by the traditional micro-electro-mechanical-system (MEMS) techniques and XRD, VSM were used to characterize the performance of the electromagnet. The planar electromagnet exhibits superior perpendicular magnetic anisotropy (PMA) and 0.006 emu of MS was achieved following 2 min deposition of CoFeB thin film. By integrating with other micro apparatuses, it is anticipated that the planar electromagnet will have potential applications in areas such as biosensors, biological medicine, drug delivery, chemical analysis and environmental monitoring.
Optimal Design and Tradeoffs Analysis for Planar Transformer in High Power DC-DC Converters
DEFF Research Database (Denmark)
Ouyang, Ziwei; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2010-01-01
A planar magnetic is a low profile transformer or inductor utilizing planar windings instead of the traditional windings made of Cu-wires. In this paper, the important factors for planar transformer design including winding loss, core loss, leakage inductance and stray capacitance have been.......2-kW full-bridge DC-DC converter prototype employing the improved planar transformer structure has been constructed, over 96% efficiency is achieved and a 2.7% improvement compared to the non-interleaving structure is obtained....
Substrate and coating defect planarization strategies for high-laser-fluence multilayer mirrors
International Nuclear Information System (INIS)
Stolz, Christopher J.; Wolfe, Justin E.; Mirkarimi, Paul B.; Folta, James A.; Adams, John J.; Menor, Marlon G.; Teslich, Nick E.; Soufli, Regina; Menoni, Carmen S.; Patel, Dinesh
2015-01-01
Planarizing or smoothing over nodular defects in multilayer mirrors can be accomplished by a discrete deposit-and-etch process that exploits the angle-dependent etching rate of optical materials. Typically, nodular defects limit the fluence on mirrors irradiated at 1064 nm with 10 ns pulse lengths due to geometrically- and interference-induced light intensification. Planarized hafina/silica multilayer mirrors have demonstrated > 125 J/cm 2 laser resistance for single-shot testing and 50 J/cm 2 for multi-shot testing for nodular defects originating on the substrate surface. Two planarization methods were explored: thick planarization layers on the substrate surface and planarized silica layers throughout the multilayer in which only the silica layers that are below one half of the incoming electric field value are etched. This paper also describes the impact of planarized defects that are buried within the multilayer structure compared to planarized substrate particulate defects. - Highlights: • Defect planarization significantly improves multilayer mirror laser resistance • Substrate and coating defects have both been effectively planarized • Single and multishot laser resistance improvement was demonstrated
The number of colorings of planar graphs with no separating triangles
DEFF Research Database (Denmark)
Thomassen, Carsten
2017-01-01
A classical result of Birkhoff and Lewis implies that every planar graph with . n vertices has at least . 152n-1 distinct 5-vertex-colorings. Equality holds for planar triangulations with . n-4 separating triangles. We show that, if a planar graph has no separating triangle, then it has at least...... . (2+10-12)n distinct 5-vertex-colorings. A similar result holds for . k-colorings for each fixed . k≥5. Infinitely many planar graphs without separating triangles have less than . 2.252n distinct 5-vertex-colorings. As an auxiliary result we provide a complete description of the infinite 6-regular...
Modeling and vector control of planar magnetic levitator
Energy Technology Data Exchange (ETDEWEB)
Kim, W. [SatCon Technology Corp., Cambridge, MA (United States); Trumper, D.L.; Lang, J.H. [Massachusetts Inst. of Tech., Cambridge, MA (United States)
1998-11-01
The authors designed and implemented a magnetically levitated stage with large planar motion capability. This planar magnetic levitator employs four novel permanent-magnet linear motors. Each motor generates vertical force for suspension against gravity, as well as horizontal force for drive. These linear levitation motors can be used as building blocks in the general class of multi-degree-of-freedom motion stages. In this paper, the authors discuss electromechanical modeling and real-time vector control of such a permanent-magnet levitator. They describe the dynamics in a dq frame introduced to decouple the forces acting on the magnetically levitated moving part, namely, the platen. A transformation similar to the Blondel-Park transformation is derived for commutation of the stator phase currents. The authors provide test results on step responses of the magnetically levitated stage. It shows 5-nm rms positioning noise in x and y, which demonstrates the applicability of such stages in the next-generation photolithography in semiconductor manufacturing.
Microwave Power Measurements on the Recirculating Planar Magnetron
Jordan, N. M.; Franzi, M.; Greening, G. B.; Gilgenbach, R. M.; Simon, D. H.; Lau, Y. Y.; Hoff, B. W.; Luginsland, J. W.
2014-10-01
The recirculating planar magnetron (RPM) is a high power microwave generator that recirculates the beam in two-coupled, planar magnetrons. Experiments on the first L-band prototype have successfully produced 50--200 μs, 30-130 MW microwave pulses with instantaneous electronic efficiencies of up to 30% at approximately 1 GHz. The device is driven using MELBA-C, with parameters of: -300 kV for 0.3-1.0 μs, and 0.15-0.3 T axial magnetic fields. Recent RPM experiments have explored the effect of cathode surface treatment on the extracted microwave power, efficiency, and pulse width. This work utilized a proof of principle extraction system with antennas on the center vane of each oscillator to couple RF power into two, coaxial transmission lines. An advanced design, the Coaxial All Cavity Extractor, is in fabrication and will be discussed. Research supported by AFOSR Grant #FA9550-10-1-0104 and by AFRL.
Hybrid planar lightwave circuits for defense and aerospace applications
Zhang, Hua; Bidnyk, Serge; Yang, Shiquan; Balakrishnan, Ashok; Pearson, Matt; O'Keefe, Sean
2010-04-01
We present innovations in Planar Lightwave Circuits (PLCs) that make them ideally suited for use in advanced defense and aerospace applications. We discuss PLCs that contain no micro-optic components, no moving parts, pose no spark or fire hazard, are extremely small and lightweight, and are capable of transporting and processing a range of optical signals with exceptionally high performance. This PLC platform is designed for on-chip integration of active components such as lasers and detectors, along with transimpedance amplifiers and other electronics. These active components are hybridly integrated with our silica-on-silicon PLCs using fully-automated robotics and image recognition technology. This PLC approach has been successfully applied to the design and fabrication of multi-channel transceivers for aerospace applications. The chips contain hybrid DFB lasers and high-efficiency detectors, each capable of running over 10 Gb/s, with mixed digital and analog traffic multiplexed to a single optical fiber. This highlyintegrated functionality is combined onto a silicon chip smaller than 4 x 10 mm, weighing failures after extreme temperature cycling through a range of > 125 degC, and more than 2,000 hours operating at 95 degC ambient air temperature. We believe that these recent advancements in planar lightwave circuits are poised to revolutionize optical communications and interconnects in the aerospace and defense industries.
Split Euler Tours In 4-Regular Planar Graphs
Directory of Open Access Journals (Sweden)
Couch PJ
2016-02-01
Full Text Available The construction of a homing tour is known to be NP-complete. On the other hand, the Euler formula puts su cient restrictions on plane graphs that one should be able to assert the existence of such tours in some cases; in particular we focus on split Euler tours (SETs in 3-connected, 4-regular, planar graphs (tfps. An Euler tour S in a graph G is a SET if there is a vertex v (called a half vertex of S such that the longest portion of the tour between successive visits to v is exactly half the number of edges of G. Among other results, we establish that every tfp G having a SET S in which every vertex of G is a half vertex of S can be transformed to another tfp G′ having a SET S′ in which every vertex of G′ is a half vertex of S′ and G′ has at most one point having a face configuration of a particular class. The various results rely heavily on the structure of such graphs as determined by the Euler formula and on the construction of tfps from the octahedron. We also construct a 2-connected 4-regular planar graph that does not have a SET.
Realisation of an anode supported planar SOFC system
Energy Technology Data Exchange (ETDEWEB)
Buchkremer, H.P.; Stoever, D. [Institut fuer Werkstoffe der Energietechnik, Juelich (Germany); Diekmann, U. [Zentralabteilung Technologie, Juelich (Germany)] [and others
1996-12-31
Lowering the operating temperature of S0FCs to below 800{degrees}C potentially lowers production costs of a SOFC system because of a less expensive periphery and is able to guarantee sufficient life time of the stack. One way of achieving lower operating temperatures is the development of new high conductive electrolyte materials. The other way, still based on state-of-the-art material, i.e. yttria-stabilized zirconia (YSZ) electrolyte, is the development of a thin film electrolyte concept. In the Forschungszentrum Julich a program was started to produce a supported planar SOFC with an YSZ electrolyte thickness between 10 to 20 put. One of the electrodes, i.e. the anode, was used as support, in order not to increase the number of components in the SOFC. The high electronic conductivity of the anode-cermet allows the use of relatively thick layers without increasing the cell resistance. An additional advantage of the supported planar concept is the possibility to produce single cells larger than 10 x 10 cm x cm, that is with an effective electrode cross area of several hundred cm{sup 2}.
An in-situ measuring method for planar straightness error
Chen, Xi; Fu, Luhua; Yang, Tongyu; Sun, Changku; Wang, Zhong; Zhao, Yan; Liu, Changjie
2018-01-01
According to some current problems in the course of measuring the plane shape error of workpiece, an in-situ measuring method based on laser triangulation is presented in this paper. The method avoids the inefficiency of traditional methods like knife straightedge as well as the time and cost requirements of coordinate measuring machine(CMM). A laser-based measuring head is designed and installed on the spindle of a numerical control(NC) machine. The measuring head moves in the path planning to measure measuring points. The spatial coordinates of the measuring points are obtained by the combination of the laser triangulation displacement sensor and the coordinate system of the NC machine, which could make the indicators of measurement come true. The method to evaluate planar straightness error adopts particle swarm optimization(PSO). To verify the feasibility and accuracy of the measuring method, simulation experiments were implemented with a CMM. Comparing the measurement results of measuring head with the corresponding measured values obtained by composite measuring machine, it is verified that the method can realize high-precise and automatic measurement of the planar straightness error of the workpiece.
Planar compaction of ceramic powders with mining explosives
International Nuclear Information System (INIS)
Stuivinga, M.; Verbeek, H.J.; Carton, E.P.
2000-01-01
Shock compaction experiments of B 4 C powders have been performed using a planar configuration. The powders were contained between metal plates. On top of the upper plate, having a thickness of about 10 mm, was a layer of mining explosives. For this configuration, computer simulations have been performed with use of the hydrocode Autodyn. In comparison with the cylindrical compaction process the planar compaction process appears to be quite different. The reason is the very low detonation velocity of the used mining explosives (2-4 km/s), which is much lower than the sound and shock speeds of the steel plate, in combination with the relatively large thickness of the metal layer. As a result, the nature of the compaction process of the powder initially more resembles a quasi-static compaction process than a shock compaction process. Due to the quasi-static nature of the compaction, the pressure release in the powder after compression is very gradual. Therefore, no strong rarefaction waves leading to high tensile stresses in the compact arise. Flat plates (10x10 cm, 0.6-0.8 cm thick) of Al (20-30 vol %) infiltrated B 4 C have been fabricated using this configuration
Probabilistic Prognosis of Non-Planar Fatigue Crack Growth
Leser, Patrick E.; Newman, John A.; Warner, James E.; Leser, William P.; Hochhalter, Jacob D.; Yuan, Fuh-Gwo
2016-01-01
Quantifying the uncertainty in model parameters for the purpose of damage prognosis can be accomplished utilizing Bayesian inference and damage diagnosis data from sources such as non-destructive evaluation or structural health monitoring. The number of samples required to solve the Bayesian inverse problem through common sampling techniques (e.g., Markov chain Monte Carlo) renders high-fidelity finite element-based damage growth models unusable due to prohibitive computation times. However, these types of models are often the only option when attempting to model complex damage growth in real-world structures. Here, a recently developed high-fidelity crack growth model is used which, when compared to finite element-based modeling, has demonstrated reductions in computation times of three orders of magnitude through the use of surrogate models and machine learning. The model is flexible in that only the expensive computation of the crack driving forces is replaced by the surrogate models, leaving the remaining parameters accessible for uncertainty quantification. A probabilistic prognosis framework incorporating this model is developed and demonstrated for non-planar crack growth in a modified, edge-notched, aluminum tensile specimen. Predictions of remaining useful life are made over time for five updates of the damage diagnosis data, and prognostic metrics are utilized to evaluate the performance of the prognostic framework. Challenges specific to the probabilistic prognosis of non-planar fatigue crack growth are highlighted and discussed in the context of the experimental results.
Echo-planar MR cerebral blood volume mapping of glomas. Clinical utility
International Nuclear Information System (INIS)
Aronen, H.J.; Univ. Central Hospital, Helsinki; Glass, J.; Pardo, F.S.; Belliveau, J.W.; Gruber, M.L.; Buchbinder, B.R.; Gazit, I.E.; Linggood, R.M.; Fischman, A.J.; Rosen, F.S.; Hochberg, F.H.
1995-01-01
Neovascularization is a common phenomenon in gliomas. MR imaging cerebral blood volume (CBV) mapping utilizes ultrafast echo-planar imaging and simultaneous use of gadolinium-based contrast material. To determine the utility of MR CBV mapping in the clinical evaluation of gliomas, we followed 15 patients with serial studies. This technique provided functional information that was not evident with conventional CT or MR imaging. Low-grade tumors demonstrated homogeneously low CBV, while high-grade tumors often showed areas of both high and low CBV. The maximum tumor CBV/white matter ratio was compared between low- (n=3) and high-grade gliomas (n=5) in patients without previous treatment and with histologic verification (n=8) and was significantly higher in high-grade gliomas (p<0.01), High CBV foci in nonenhancing tumor areas were present in 2 cases. The distinction between radiation necrosis and active tumor could be made correctly in 3 of 4 cases. The information provided by MR CBV mapping has the potential to be an adjunct in the clinical care of glioma patients. (orig.)
Chauhan, Munish; Vidya Shankar, Rohini; Ashok Kumar, Neeta; Kodibagkar, Vikram D; Sadleir, Rosalind
2018-01-01
Magnetic resonance electrical impedance tomography (MREIT) sequences typically use conventional spin or gradient echo-based acquisition methods for reconstruction of conductivity and current density maps. Use of MREIT in functional and electroporation studies requires higher temporal resolution and faster sequences. Here, single and multishot echo planar imaging (EPI) based MREIT sequences were evaluated to see whether high-quality MREIT phase data could be obtained for rapid reconstruction of current density, conductivity, and electric fields. A gel phantom with an insulating inclusion was used as a test object. Ghost artifact, geometric distortion, and MREIT correction algorithms were applied to the data. The EPI-MREIT-derived phase-projected current density and conductivity images were compared with simulations and spin-echo images as a function of EPI shot number. Good agreement among measures in simulated, spin echo, and EPI data was achieved. Current density errors were stable and below 9% as the shot number decreased from 64 to 2, but increased for single-shot images. Conductivity reconstruction relative contrast ratios were stable as the shot number decreased. The derived electric fields also agreed with the simulated data. The EPI methods can be combined successfully with MREIT reconstruction algorithms to achieve fast imaging of current density, conductivity, and electric field. Magn Reson Med 79:71-82, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
3D tomographic imaging with the γ-eye planar scintigraphic gamma camera
Tunnicliffe, H.; Georgiou, M.; Loudos, G. K.; Simcox, A.; Tsoumpas, C.
2017-11-01
γ-eye is a desktop planar scintigraphic gamma camera (100 mm × 50 mm field of view) designed by BET Solutions as an affordable tool for dynamic, whole body, small-animal imaging. This investigation tests the viability of using γ-eye for the collection of tomographic data for 3D SPECT reconstruction. Two software packages, QSPECT and STIR (software for tomographic image reconstruction), have been compared. Reconstructions have been performed using QSPECT’s implementation of the OSEM algorithm and STIR’s OSMAPOSL (Ordered Subset Maximum A Posteriori One Step Late) and OSSPS (Ordered Subsets Separable Paraboloidal Surrogate) algorithms. Reconstructed images of phantom and mouse data have been assessed in terms of spatial resolution, sensitivity to varying activity levels and uniformity. The effect of varying the number of iterations, the voxel size (1.25 mm default voxel size reduced to 0.625 mm and 0.3125 mm), the point spread function correction and the weight of prior terms were explored. While QSPECT demonstrated faster reconstructions, STIR outperformed it in terms of resolution (as low as 1 mm versus 3 mm), particularly when smaller voxel sizes were used, and in terms of uniformity, particularly when prior terms were used. Little difference in terms of sensitivity was seen throughout.
Directory of Open Access Journals (Sweden)
Thomas Jerry A
2010-11-01
Full Text Available Abstract Background Calibrating mammograms to produce a standardized breast density measurement for breast cancer risk analysis requires an accurate spatial measure of the compressed breast thickness. Thickness inaccuracies due to the nominal system readout value and compression paddle orientation induce unacceptable errors in the calibration. Method A thickness correction was developed and evaluated using a fully specified two-component surrogate breast model. A previously developed calibration approach based on effective radiation attenuation coefficient measurements was used in the analysis. Water and oil were used to construct phantoms to replicate the deformable properties of the breast. Phantoms consisting of measured proportions of water and oil were used to estimate calibration errors without correction, evaluate the thickness correction, and investigate the reproducibility of the various calibration representations under compression thickness variations. Results The average thickness uncertainty due to compression paddle warp was characterized to within 0.5 mm. The relative calibration error was reduced to 7% from 48-68% with the correction. The normalized effective radiation attenuation coefficient (planar representation was reproducible under intra-sample compression thickness variations compared with calibrated volume measures. Conclusion Incorporating this thickness correction into the rigid breast tissue equivalent calibration method should improve the calibration accuracy of mammograms for risk assessments using the reproducible planar calibration measure.
DEFF Research Database (Denmark)
Jensen, Rasmus Ramsbøl; Benjaminsen, Claus; Larsen, Rasmus
2015-01-01
The application of motion tracking is wide, including: industrial production lines, motion interaction in gaming, computer-aided surgery and motion correction in medical brain imaging. Several devices for motion tracking exist using a variety of different methodologies. In order to use such devices...... offset and tracking noise in medical brain imaging. The data are generated from a phantom mounted on a rotary stage and have been collected using a Siemens High Resolution Research Tomograph for positron emission tomography. During acquisition the phantom was tracked with our latest tracking prototype...
Streamline correction for the analysis of boundary layer turbulence
Lee, Zoë S.; Baas, Andreas C. W.
2012-10-01
Improvements in the design and affordability of ultrasonic anemometers have provided significant contributions to aeolian research, by facilitating high frequency monitoring of three dimensional wind velocities. From these data it is possible to calculate quasi-instantaneous Reynolds stresses to evaluate boundary layer turbulence, moving beyond time-averaged measures, such as shear velocity (U*). As ultrasonic anemometry is used more frequently in aeolian geomorphology it is important to question accepted conventions concerning data processing and analysis. This paper examines data processing questions associated with the application of ultrasonic anemometry to field studies in aeolian geomorphology, through an investigation of three streamline correction routines, the two-step, three-step and planar-fit methods, on data recorded on a gently sloping beach at Magilligan Strand, Northern Ireland in May 2010. The planar-fit technique has not previously been used in aeolian geomorphology. Results are compared with data that have been corrected only for wind direction (yaw). The effects that these different methods have on quadrant analysis and Reynolds stress calculation are discussed. Streamline correction is applied as a time-variable procedure using a characteristic timescale of 8 s following analysis of the resultant wind speed energy spectrum. It is found that Reynolds shear stress is dependent on streamline correction method, with run mean estimates of resultant horizontal shear stress ranging from 0.05 to 0.11 N m- 2 depending on the technique. The two-step method consistently maximises the shear stress and when the resultant horizontal shear is calculated, it produces the most robust estimate for application to aeolian research. In contrast, the different methods have little effect on the identification or sequencing of turbulent structures using quadrant analysis. Streamline correction is an essential processing step when using Reynolds decomposition, however
KODAMA, Nao; KOSE, Katsumi
2016-01-01
Echo-planar imaging (EPI) sequences were developed for a 9.4 Tesla vertical standard bore (∼54 mm) superconducting magnet using an unshielded gradient coil optimized for live mice imaging and a data correction technique with reference scans. Because EPI requires fast switching of intense magnetic field gradients, eddy currents were induced in the surrounding metallic materials, e.g., the room temperature bore, and this produced serious artifacts on the EPI images. We solved the problem using an unshielded gradient coil set of proper size (outer diameter = 39 mm, inner diameter = 32 mm) with time control of the current rise and reference scans. The obtained EPI images of a phantom and a plant sample were almost artifact-free and demonstrated the promise of our approach. PMID:27001398
DEFF Research Database (Denmark)
Martini, Enrica; Breinbjerg, Olav; Maci, Stefano
2008-01-01
A simple and effective procedure for the reduction of truncation errors in planar near-field measurements of aperture antennas is presented. The procedure relies on the consideration that, due to the scan plane truncation, the calculated plane wave spectrum of the field radiated by the antenna...... is reliable only within a certain portion of the visible region. Accordingly, the truncation error is reduced by extrapolating the remaining portion of the visible region by the Gerchberg-Papoulis iterative algorithm, exploiting a condition of spatial concentration of the fields on the antenna aperture plane....... The proposed procedure is simple and computationally efficient; it does not require any modification of the measurement procedure and it allows for the usual probe correction. Far-field patterns reconstructed from both simulated and measured truncated near-field data demonstrate its effectiveness and stability...
Using Online Annotations to Support Error Correction and Corrective Feedback
Yeh, Shiou-Wen; Lo, Jia-Jiunn
2009-01-01
Giving feedback on second language (L2) writing is a challenging task. This research proposed an interactive environment for error correction and corrective feedback. First, we developed an online corrective feedback and error analysis system called "Online Annotator for EFL Writing". The system consisted of five facilities: Document Maker,…