Showing papers on "Transverse plane published in 2011"

Polarization-independent wide-angle triple-band metamaterial absorber.

Abstract: We report the design, fabrication, and measurement of a microwave triple-band absorber. The compact single unit cell consists of three nested electric closed-ring resonators and a metallic ground plane separated by a dielectric layer. Simulation and experimental results show that the absorber has three distinctive absorption peaks at frequencies 4.06GHz, 6.73GHz, and 9.22GHz with the absorption rates of 0.99, 0.93, and 0.95, respectively. The absorber is valid to a wide range of incident angles for both transverse electric (TE) and transverse magnetic (TM) polarizations. The triple-band absorber is a promising candidate as absorbing elements in scientific and technical applications because of its multiband absorption, polarization insensitivity, and wide-angle response.

Performance of the LHCb Vertex Locator

Abstract: The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment The performance of the detector during the first years of its physics operation is reviewed The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7mm from the LHC beam for physics data taking The performance and stability of these characteristic features of the detector are described, and details of the material budget are given The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described The system performance is fully characterised The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 mu m is achieved at the optimal track angle The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 05%, and the detector has less than 1% of faulty strips The proximity of the detector to the beam means that the inner regions of the n(+)-on-n sensors have undergone space-charge sign inversion due to radiation damage The VELO performance parameters that drive the experiment's physics sensitivity are also given The track finding efficiency of the VELO is typically above 98% and the modules have been aligned to a precision of 1 mu m for translations in the plane transverse to the beam A primary vertex resolution of 13 mu m in the transverse plane and 71 mu m along the beam axis is achieved for vertices with 25 tracks An impact parameter resolution of less than 35 mu m is achieved for particles with transverse momentum greater than 1GeV/c

Missing transverse energy performance of the CMS detector

Abstract: During 2010 the LHC delivered pp collisions with a centre-of-mass energy of 7 TeV. In this paper, the results of comprehensive studies of missing transverse energy as measured by the CMS detector are presented. The results cover the measurements of the scale and resolution for missing transverse energy, and the effects of multiple pp interactions within the same bunch crossings on the scale and resolution. Anomalous measurements of missing transverse energy are studied, and algorithms for their identification are described. The performances of several reconstruction algorithms for calculating missing transverse energy are compared. An algorithm, called missing-transverse-energy significance, which estimates the compatibility of the reconstructed missing transverse energy with zero, is described, and its performance is demonstrated.

Transverse and normal interfacial stiffness of solids with randomly rough surfaces

Abstract: Using a theoretical approach and computer simulations, we calculate the normal stiffness and the transverse stiffness of the interface between two contacting isotropic solids with randomly rough surfaces and Poisson ratio ν. The theoretical predictions for agree well with the simulations. Moreover, the theoretical result for the ratio is (2 − ν)/(2 − 2ν), as predicted by Mindlin for a single circular contact region. Finally, we compare the theory to experimental ultrasonic data.

The growth and coalescence of ellipsoidal voids in plane strain under combined shear and tension

Abstract: New extensions of a model for the growth and coalescence of ellipsoidal voids based on the Gurson formalism are proposed in order to treat problems involving shear and/or voids axis not necessarily aligned with the main loading direction, under plane strain loading conditions. These extensions are motivated and validated using 3D finite element void cell calculations with overall plane strain enforced in one direction. The starting point is the Gologanu model dealing with spheroidal void shape. A void rotation law based on homogenization theory is coupled to this damage model. The predictions of the model closely agree with the 3D cell calculations, capturing the effect of the initial void shape and orientation on the void rotation rate. An empirical correction is also introduced for the change of the void aspect ratio in the plane transverse to the main axis of the void departing from its initially circular shape. This correction is needed for an accurate prediction of the onset of coalescence. Next, a new approach is proposed to take strain hardening into account within the Thomason criterion for internal necking, avoiding the use of strain hardening-dependent fitting parameters. The coalescence criterion is generalized to any possible direction of the coalescence plane and void orientation. Finally, the model is supplemented by a mathematical description of the final drop of the stress carrying capacity during coalescence. The entire model is developed for plane strain conditions, setting the path to a 3D extension. After validation of the model, a parametric study addresses the effect of shear on the ductility of metallic alloys for a range of microstructural and flow parameters, under different stress states. In general, the presence of shear, for identical stress triaxiality, decreases the ductility, partly explaining recent experimental results obtained in the low stress triaxiality regime.

Disturbance Field Characteristics of a Transversely Excited Burner

Abstract: Transverse acoustic instabilities in premixed, swirl-stabilized flames are an important problem in low NOx combustors. Transverse excitation of swirling flames involves complex interactions between acoustic waves and fluid mechanic instabilities. This paper presents high-speed PIV characterization of the flow field characteristics of a swirling, annular jet under reacting and nonreacting conditions. These data show that the flame response to transverse acoustic excitation is a superposition of acoustic and vortical disturbances that fluctuate in both the longitudinal and transverse direction. In the nozzle near-field region, the disturbance field is a complex superposition of short wavelength and convecting vortical disturbances, as well as longer wavelength transverse and longitudinal acoustic disturbances. Very near the nozzle, distinct vortical structures are evident that are associated with the separating inner and outer annulus shear layers. Their relative phasing on the left and right side of the bu...

Neutrino Quasielastic Scattering on Nuclear Targets Parametrizing Transverse Enhancement (Meson Exchange Currents)

Abstract: We present a parametrization of the observed enhancement in the transverse electron quasielastic (QE) response function for nucleons bound in carbon as a function of the square of the four momentum transfer (Q 2) in terms of a correction to the magnetic form factors of bound nucleons. The parametrization should also be applicable to the transverse cross section in neutrino scattering. If the transverse enhancement originates from meson exchange currents (MEC), then it is theoretically expected that any enhancement in the longitudinal or axial contributions is small. We present the predictions of the “Transverse Enhancement” model (which is based on electron scattering data only) for the ν μ , $\bar{ u}_{\mu}$ differential and total QE cross sections for nucleons bound in carbon. The Q 2 dependence of the transverse enhancement is observed to resolve much of the long standing discrepancy in the QE total cross sections and differential distributions between low energy and high energy neutrino experiments on nuclear targets.

Stochastic flux-related analysis of transverse mixing in two-dimensional heterogeneous porous media

Abstract: [1] Transverse mixing of solutes in steady state transport is of utmost importance for assessing mixing-controlled reactions of compounds that are continuously introduced into the subsurface. Classical spatial moments analysis fails to describe mixing because the tortuous streamlines in heterogeneous formations cause plume meandering, squeezing, and stretching, which affect transverse spatial moments even if there is no mass transfer perpendicular to the direction of flow. For transverse solute mixing, however, the decisive process is the exchange of solute mass between adjacent stream tubes. We therefore reformulate the advection-dispersion equation in streamline coordinates (i.e., in terms of the potential and the stream function values) and analyze how flux-related second central moments of plumes increase with dropping hydraulic potential. We compare the ensemble behavior of these second central moments in random two-dimensional heterogeneous flow fields with the moments in an equivalent homogeneous system, thus defining an equivalent effective transverse dispersion coefficient. Unlike transverse macrodispersion coefficients derived by traditional moment analysis, our mixing-relevant, flux-related coefficient does not increase with travel distance. We present closed-form solutions for the mean enhancement of transverse mixing by heterogeneity in two-dimensional isotropic media for linear laws of local-scale transverse dispersion. The mixing enhancement factor increases with the log conductivity variance but remains fairly low. We also evaluate the variance of our cumulative measure of transverse mixing, showing that heterogeneity causes substantial uncertainty of mixing. The analytical expressions are compared to numerical Monte Carlo simulations for various values of log conductivity variance, indicating good agreement with the analytical results at low variability. In the numerical simulations, we also consider nonlinear models of local-scale transverse dispersion.

Observation of the in-plane spin separation of light

Abstract: We report on the observation of the spin separation of light in the plane of incidence when a linearly polarized beam is reflected or refracted at a planar dielectric interface. Remarkably, the in-plane spin separation reaches hundreds of nanometers, comparable with the transverse spin separation induced by the well-known spin Hall effect of light. The observation is properly explained by considering the in-plane spread of wave-vectors. This study thus offers new insights on the spinoptics and may provide a potential method to control light in optical nanodevices.

Inclined negatively buoyant jets 2: concentration measurements

Abstract: Experiments on concentration measurements in round turbulent negatively buoyant jets discharging into a calm homogeneous fluid at three different angles are presented. Detailed measurements using a micro-scale conductivity probe were carried out at the horizontal location of the terminal rise height, mostly along the vertical of the axial jet plane and in the transverse direction. The dimensionless vertical distribution of the mean concentration is found to be asymmetric, whereas the transverse distribution is approximately Gaussian. At the same horizontal location, the vertical distribution of the concentration turbulent intensity has a maximum at a point systematically higher than the jet axis. The width of the mean concentration distribution, the heights to the location of the maximum mean concentration and to the maximum turbulent intensity as well as the minimum dilution are determined. From measurements in the region where the jet returns to the source elevation, the minimum dilution and the horizon...

Transverse oscillations of loops with coronal rain observed by Hinode/SOT

Abstract: The condensations composing coronal rain, falling down along loop-like structures observed in cool chromospheric lines such as H$\alpha$ and \ion{Ca}{2} H, have long been a spectacular phenomenon of the solar corona. However, considered a peculiar sporadic phenomenon, it has not received much attention. This picture is rapidly changing due to recent high resolution observations with instruments such as \textit{Hinode}/SOT, CRISP of \textit{SST} and \textit{SDO}. Furthermore, numerical simulations have shown that coronal rain is a loss of thermal equilibrium of loops linked to footpoint heating. This result has highlighted the importance that coronal rain can play in the field of coronal heating. In this work, we further stress the importance of coronal rain by showing the role it can play in the understanding of the coronal magnetic field topology. We analyze \textit{Hinode}/SOT observations in the \ion{Ca}{2} H line of a loop in which coronal rain puts in evidence in-phase transverse oscillations of multiple strand-like structures. The periods, amplitudes, transverse velocities and phase velocities are calculated, allowing an estimation of the energy flux of the wave and the coronal magnetic field inside the loop through means of coronal seismology. We discuss the possible interpretations of the wave as either standing or propagating torsional Alfven or fast kink waves. An estimate of the plasma beta parameter of the condensations indicates a condition that may allow the often observed separation and elongation processes of the condensations. We also show that the wave pressure from the transverse wave can be responsible for the observed low downward acceleration of coronal rain.

A Taller-Than-Wide Shape in Thyroid Nodules in Transverse and Longitudinal Ultrasonographic Planes and the Prediction of Malignancy

Abstract: Background: A “taller-than-wide” shape is associated with thyroid malignancy, but taller-than-wide in which plane is most accurate is unclear. We determined in which ultrasonography (US) plane a taller-than-wide shape is most predictive of malignancy. Methods: A total of 471 thyroid nodules from 435 patients were studied. The final diagnosis was based on histopathology in 145 nodules in 120 patients, and cytology in the remaining patients. A taller-than-wide shape was defined as a ratio of ≥1, calculated by dividing the anteroposterior diameter by the transverse diameter. Three criteria were formulated as follows: criterion 1, a taller-than-wide in any plane as a suspicious feature; criterion 2, that in the transverse plane; criterion 3, that in the longitudinal plane. The sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (Az) were compared among the three criteria. Result: Of the 471 lesions, 125 (26.5%) were classif...

Nonlinear vibration control of functionally graded plate with piezoelectric layers in thermal environment

Abstract: In this paper, large amplitude vibration control of functionally graded material (FGM) plates under thermal gradient and transverse mechanical loads using integrated piezoelectric sensor/actuator layers is investigated. In this regard, finite element formulation based on higher order shear deformation plate theory is developed. The von Karman nonlinear strain-displacement relationship is used to account for the large deflection of the plate. The material properties of FGM are assumed to be temperature-dependent and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The temperature field is assumed to be constant in the plane and varied only in the thickness direction of the plate. In order to control the large amplitude vibration of the plate, two control algorithms are employed: classical displacement-velocity feedback control and robust H2 control. Also, the uncertainty which arises from external disturbances (low-frequenc...

Ultracompact and fabrication-tolerant integrated polarization splitter.

Abstract: Design and fabrication of a 2×2 two-mode interference (TMI) coupler based on-chip polarization splitter is presented. By changing the angle between the access waveguides, one can tune the effective TMI length for the mode with less optical confinement (transverse magnetic, TM) to coincide with the target TMI length for a desired transmission of the mode with higher optical confinement (transverse electric, TE). The fabricated 0.94 μm long 2×2 TMI splits the input power into TM (bar) and TE (cross) outputs with splitting ratio over 15 dB over 50 nm bandwidth. Fabrication tolerance analysis shows that the device is tolerant to fabrication errors as large as 60 nm.

Rotating electro-osmotic flow over a plate or between two plates.

Abstract: In this paper, we investigate rotating electro-osmotic (EO) flow over an infinite plate or in a channel formed by two parallel plates. The analysis is based on the Debye-Huckel approximation for charge distributions and the Navier-Stokes equation for a transport electrolyte in the rotating frame. It is shown that, for the single plate, the nondimensional speed of system rotation ω is the singly most important parameter, while for the channel, in addition to ω, the nondimensional electrokinetic width K also plays an important role. However, the parameter ω≡η(2) has different natural appearances in the respective cases of a single plate (SP) and two plates (TPs). More precisely, η(SP) measures the ratio λ(D)/L(K) of the Debye length to the Ekman depth, while η(TP) measures the ratio L/L(K) of the channel width to the Ekman depth. The effect of rotation is always to reduce the axial flow rate along the direction of the applied electric field, accompanied by a (secondary) transverse flow. In the SP case, the plot on the velocity plane for each ω shows an interesting closed EO Ekman spiral. The size of the spiral shrinks with increasing ω. The transverse flow is so significant that the volume transport associated with the EO Ekman spiral turns clockwise 45° to the applied field near ω=0 and gradually turns at a right angle to the applied field as ω is increased. In contrast, in the TP case, the transverse flow rate is smaller than the axial flow rate when ω is small. The transverse flow rates at all K are observed to reach their maxima at ω of order 1. The volume transport is nearly at a zero angle to the applied field near ω=0 and gradually turns to 45° to the applied field as ω is increased. In the limit of ω→∞, for both SP and TP cases, the entire system forms a rigid body rotation-there is neither axial nor transverse flow.

Modal Analysis of Dielectric-Filled Rectangular Waveguide With Transverse Slots

Abstract: The dispersion relations and modes for a dielectric-filled rectangular waveguide with transverse slots are investigated. The differences between the air-filled and the dielectric-filled rectangular waveguides with transverse slots are analyzed. The dielectric-filled rectangular waveguide with transverse slots supports a leaky waveguide mode, a surface-wave mode and a proper waveguide mode. The complex propagation wavenumber is calculated by enforcing an aperture magnetic field integral equation using either a space-domain approach or a spectral-domain approach. The physical significance of the solutions is explained. The theoretical results agree very well with the results from HFSS simulation.

Acoustic–convective mode conversion in an aerofoil cascade

Abstract: When an acoustic wave impinges on an aerofoil cascade, a convective vorticity mode is generated giving rise to transverse velocity perturbations. This mode conversion process is investigated to explain the flow dynamics observed when swirlers are submitted to incident acoustic disturbances. The phenomenon is first studied in the case of a two-dimensional aerofoil cascade using a model derived from an actuator disk theory. The model is simplified to deal with low-Mach-number flows. The velocity field on the downstream side of the cascade features two components, an axial perturbation associated with the transmitted acoustic wave and a transverse disturbance corresponding to the vorticity wave generated at the cascade trailing edge. The model provides the amplitude of both components and defines their phase shift. Numerical simulations are carried out in a second stage to validate this model in the case of a cascade operating at a low Reynolds number Rec = 2700 based on the chord length. Space–time diagrams of velocity perturbations deduced from these simulations are used to retrieve the two types of modes. Experiments are then carried out in the case of an axial swirler placed in a cylindrical duct and submitted to plane acoustic waves emitted on the upstream side of the swirler. The amplitude and phase of the two velocity components measured in the axial and azimuthal directions are found to be in good agreement with theoretical estimates and with numerical calculations. This analysis is motivated by combustion dynamics observed in flames stabilized by aerodynamic swirlers in continuous combustors.

Sensitivity of the transverse flow to the symmetry energy

Abstract: We study the sensitivity of transverse flow to symmetry energy in the Fermi energy region as well as at high energies. We find that transverse flow is sensitive to symmetry energy and its density dependence in the Fermi energy region. We also show that the transverse flow can address the symmetry energy at densities about twice the saturation density; however, it shows insensitivity to the symmetry energy at densities $\ensuremath{\rho}/{\ensuremath{\rho}}_{0}g2$. The mechanism for the sensitivity of transverse flow to symmetry energy and its density dependence is also discussed.

Transverse instability of dunes.

Abstract: The simplest type of dune is the transverse one, which propagates with invariant profile orthogonally to a fixed wind direction. Here we show, by means of numerical simulations, that transverse dunes are unstable with respect to along-axis perturbations in their profile and decay on the bedrock into barchan dunes. Any forcing modulation amplifies exponentially with growth rate determined by the dune turnover time. We estimate the distance covered by a transverse dune before fully decaying into barchans and identify the patterns produced by different types of perturbation.

Resonantly damped propagating kink waves in longitudinally stratified solar waveguides

Abstract: It has been shown that resonant absorption is a robust physical mechanism for explaining the observed damping of magnetohydrodynamic kink waves in the solar atmosphere due to naturally occurring plasma inhomogeneity in the direction transverse to the direction of the magnetic field. Theoretical studies of this damping mechanism were greatly inspired by the first observations of post-flare standing kink modes in coronal loops using the Transition Region and Coronal Explorer. More recently, these studies have been extended to explain the attenuation of propagating coronal kink waves observed by the Coronal Multi-Channel Polarimeter. In the present study, for the first time we investigate the properties of propagating kink waves in solar waveguides including the effects of both longitudinal and transverse plasma inhomogeneity. Importantly, it is found that the wavelength is only dependent on the longitudinal stratification and the amplitude is simply a product of the two effects. In light of these results the advancement of solar atmospheric magnetoseismology by exploiting high spatial/temporal resolution observations of propagating kink waves in magnetic waveguides to determine the length scales of the plasma inhomogeneity along and transverse to the direction of the magnetic field is discussed.

Transverse instability of the line solitary water-waves

Abstract: We prove the linear and nonlinear instability of the line solitary water waves with respect to transverse perturbations.

Transverse Oscillations of Coronal Loops with Slowly Changing Density

Abstract: In this paper we study kink oscillations of coronal loops with the density varying along the loop and also slowly changing with time. Using the Wentzel–Kramers–Brillouin (WKB) method we obtain the adiabatic invariant that determines the time dependence of the oscillation amplitude. The obtained general results are applied to kink oscillations of cooling loops. The main conclusion of this study is that cooling causes the amplification of kink oscillations.

Detection of a semirough target in turbulent atmosphere by a partially coherent beam.

Abstract: The inverse problem of the interaction of an isotropic Gaussian Schell-model beam with a semirough target in turbulent atmosphere is investigated. It is found that we can determine the target size and the transverse correlation width of the target by measuring the transverse beam widths and the transverse coherence widths of the beams at the source plane and the receiver plane. Our results are useful for remote sensing and bistatic LIDAR system.

A fresh look at the nucleus-endplate region: new evidence for significant structural integration

Abstract: The disc nucleus is commonly thought of as a largely unstructured gel. However, exactly how the nucleus integrates structurally with the endplates remains somewhat ambiguous. The purpose of this study was to investigate whether a substantial level of structural/mechanical cohesion does, in fact, exist across the nucleus-endplate junction. Vertebra–nucleus–vertebra samples were obtained from mature ovine lumbar motion segments and subjected to a novel technique involving circumferential transverse severing (i.e. ring-severing) of the annulus fibrosus designed to eliminate its strain-limiting influence. These samples were loaded in tension and then chemically fixed in order to preserve the stretched nucleus material. Structural continuity across the nucleus-endplate junctions was sufficient for the samples to support, on average, 20 N before tensile failure occurred. Microscopic examination revealed nucleus fibres inserting into the endplates and the significant level of load carried by the nucleus material indicates that there is some form of structural continuity from vertebra to vertebra in the central nucleus region.

Damage analysis of fiber reinforced Ti-alloy subjected to multi-axial loading—A micromechanical approach

Abstract: Effects of initiation and propagation of interface damage on the elastoplastic behavior of a unidirectional SiC/Ti metal matrix composite (MMC) subjected to multi-axial loading are studied using a three-dimensional micromechanics based analytical model. Effects of manufacturing process thermal residual stress (RS) are also included in the analysis. The selected representative volume element (RVE) consists of an r × c unit cells in which a quarter of the fiber is surrounded by matrix sub-cells. The constant compliance interface (CCI) model is used to model interfacial debonding and the successive approximation method together with Von-Mises yield criterion is used to obtain elastic–plastic behavior. Failure modes during multi-axial tensile/compressive loading in the presence of residual stresses are discussed in details. Results revealed that for more realistic predictions both interface damage and thermal residual stress effects should be considered in the analysis. Comparison between results of the presented model shows very good agreement with available finite element micromechanical analysis and experiment for uniaxial loading. Also, results are extracted and interpreted for equi-biaxial including transverse/transverse and axial/transverse and equi-triaxial loading.