Out Of Plane Component Research Articles

Vertical gradient of magnetic anisotropy in the ferromagnetic semiconductor (Ga,Mn)As film

The properties of magnetic anisotropy of GaMnAs films along the growth direction were studied by Hall effect measurements. The magnetic anisotropy fields were obtained by analyzing the angular dependence of the planar Hall resistance and the anomalous Hall resistance for in-plane and out-of plane components of the Hall signal, respectively. The magnetic anisotropy fields obtained by this process were used to construct a three-dimensional magnetic free energy diagram, which clearly shows that the out-of-plane characteristics of magnetic anisotropy become more pronounced as we approach the bottom part of the film.

Kinetic Alfvén Wave Turbulence and Transport through a Reconnection Diffusion Region

We demonstrate from observations that kinetic Alfvén waves may play an important role in facilitating magnetic reconnection. These waves radiate outwards from the diffusion region oblique to the magnetic field in a conelike pattern delimited by the X line separatrices with outward energy fluxes equivalent to that contained in the outstreaming ions. It is shown that the wave vectors reverse across the X and symmetry lines and have a large out of plane component. We estimate that these waves drive significant transport through the diffusion region.

Polarization spectroscopy of aluminum phthalocyanine hydroxide embedded in superfluid helium droplets

We report electronic polarization spectroscopy of aluminum phthalocyanine hydroxide embedded in superfluid helium droplets orientated by a DC electric field. By monitoring the laser induced fluorescence as a function of the polarization direction of the excitation laser, we conclude that the transition dipole is predominantly perpendicular to the permanent dipole. Further quantitative analysis, however, shows that the angle between the transition dipole and permanent dipole is only 74°, and the out of plane component is about 8%. This result agrees with our previous conclusion on metal phthalocyanine chlorides. We suggest that this phenomenon might be related to the out of plane central metal atom, which could introduce a n–π ∗ type transition.

A geometrically exact membrane model for isotropic foils and fabrics

where R = polar(F ) ∈ SO(3) is the orthogonal part of the deformation gradient F with out-of plane component R(x, y).e3. The variable m ∈ IR accounts for a varying thickness, see [1, 2] for details. Basic idea: introduce an additional field of independently evolving viscoelastic rotations R ∈ SO(3). These rotations R are thought of as being physical meaningful but not exact continuum rotations R. With R3 ≡ R(x, y).e3 denoting the corresponding out-of plane component the dimensional reduction of a three-dimensional continuum solid to a geometrically exact membrane model results in a deformation gradient of the form F = (∇m|mR3), (2) where ∇m ∈ M is the deformation gradient of the midsurface with mx = (m1,x,m2,x,m3,x) T , my = (m1,y,m2,y,m3,y) T . The problem: find the deformation of the midsurface m : [0, T ]× ω 7→ IR and the independent local viscoelastic rotation R : [0, T ]× ω 7→ SO(3, IR) such that

Electronic polarization spectroscopy of metal phthalocyanine chloride compounds in superfluid helium droplets

We report the electronic polarization spectroscopy of two metal phthalocyanine chloride compounds (MPcCl, M=Al,Ga) embedded in superfluid helium droplets and oriented in a dc electric field. For both compounds, the laser induced fluorescence spectra show preference for perpendicular excitation relative to the orientation field. This result indicates that the permanent dipoles of both compounds are predominantly perpendicular to the transition dipole. Since the permanent dipole derives from the metal chloride, while the transition dipole derives from the phthalocyanine chromophore, in the plane of phthalocyanine, this qualitative result is not surprising. However, quantitative modeling reveals that this intuitive model is inadequate and that the transition dipole might have tilted away from the molecular plane of phthalocyanine. The out of plane component of the transition dipole amounts to approximately 10% if the permanent dipole is assumed to be approximately 4 debye. The origin for this tilt is puzzling, and we tentatively attribute it to the transition of nonbonding orbitals, either from the chlorine atom or from the bridge nitrogen atom, to the pi* orbitals of the phthalocyanine chromophore. On the other hand, although unlikely, we cannot completely exclude the possibility that both our high level density functional theory calculation and ab initio results severely deviate from reality. The droplet matrix induces redshifts in the origin of the electronic transition and produces discrete phonon wings. Nevertheless, in dc electric fields, all phonon wings and the zero phonon line demonstrate the same dependence on the polarization direction of the excitation laser. Although electronic excitation does couple to the superfluid helium matrix and the resulting phonon wings add complications to the electronic spectrum, this coupling does not affect the direction of the electronic transition dipole. Electronic polarization spectroscopy in superfluid helium droplets is thus still informative in revealing the permanent dipole and its relation relative to the transition dipole.

미세제트 유동의 Stereoscopic micro-PIV측정

Micro-PIV(particle image velocimetry) has been widely used to measure the velocity of micro flow. Although this micro-PIV method can give accurate 2D instantaneous velocity information of mea-surement plane, it cannot resolve the out of plane component of velocity vectors. Lots of the micro fluidic devices generate three-dimensional flow and 3D measurement of velocity is useful to understand the physics of micro flow phenomena. In this study, we constructed stereoscopic micro-PIV(SMPIV) system and applied this method to the impinging micro jet flow. The results show that this method can produce accu-rate 3D reconstruction of micro jet flow.

Development of Micro-Actuators Driven by Liquid Crystals (2nd Report, Effect of Various Parameters)

As a purpose of developing liquid crystalline micro-actuators, transient behaviors of a nematic liquid crystal between two parallel plates are computed with various parameters such as applied voltage, gap of the plates, and twist and tilt angles. When the twist angle is 0 deg, the induced flow is planar, and when the twist angle is not 0 deg, on the other hand, the flow has an out of plane component. With increasing the applied voltage, the shear stress acting on the plate, the velocity, and the flow rate are increased and the response is improved. The effect of the gap of the plates is large ; when the gap is reduced to 5 μm, for example, the response is so high that the physical quantities become maxima within a couple of milliseconds. However, if the electric field intensity is kept constant, the effect of the gap is negligible. The tilt angle has comparatively little effect. We can develop micro-actuators with arbitrary characteristics by controlling properly applied voltage, size of actuators, and anchoring conditions.

Switching behavior of vortex structures in nanodisks

This work presents an experimental investigation of the switching behavior of single Co- and permalloy (Py) nanodisks employing magnetic force microscopy (MFM) and micro Hall magnetometry. We used both methods to study the magnetization reversal of individual disks with diameters between 200 nm and 2 /spl mu/m and thicknesses between 5 nm and 60 nm with a magnetic vortex phase. It is shown, that the helicity of the vortex (clockwise or counterclockwise) is independent of the direction of the normal component in the center, and vice versa. By an externally applied field it is possible to switch the direction of the central out of plane component selectively.

X-ray Flat Diffractor Optics II

In the first part of the paper [D. Korytar and P. Bohacek: Czech. J. Phys. 50 (2000) 841] a three-dimensional reciprocal space concept based on two-beam dynamical theory of X-ray diffraction has been applied for studying the general case of a flat asymmetrical inclined Bragg diffractor. Based on the results obtained, precise equations for the incident and diffracted beams have been derived and analyzed in this second part of the paper. The out-of-diffraction-plane components of the incident and diffracted beams have been studied in detail. It was concluded that in comparison with the symmetrical inclined diffractor more than one order of magnitude increase of the out of plane component of the diffracted beam can be reached for the asymmetrical inclined diffractor in grazing emergence setting. At the same time the out of plane component of the incident beam is decreased below the out of plane component for the symmetrical inclined case.

Optical Characterization of the Director Field in a Distorted Nematic Layer

We develop new optical methods using transmitted polarized light for the characterization of the out of plane component n z of the director field in a weakly distorted planar nematic layer. In extraordinary light, we relate the angles of aperture of the caustic surface to the local amplitudes of the n z distortion. In ordinary light, a new type of contrast due to the anisotropic light scattering is shown to give the map of n z 2 . We apply our methods to the study of the director distortions occuring in the thermal convection.

3-D scanning-particle-image-velocimetry: Technique and application to a spherical cap wake flow

A 3-D time-resolving and whole-volume Digital-Particle-Image-Velocimetry (DPIV) technique based on the concept of a scanning light-sheet is presented and applied here to the 3-D transient wake phenomena in the spherical cap wake flow. The technique uses a scanning light-sheet for rapid sampling of the flow in depth and a two-camera recording system for stereoscopic 3-D DPIV. Application of a correlation technique in combination with a calibration yields, aside from the correct in-plane displacement, also the out of plane component and thus the total velocity vectors within the planes of the scanning light-sheet. With a high scanning rate in comparison to the characteristic time scales the method provides the 3-D velocity field in space and time. Through the use of conventional video-techniques the temporal evolution of the complete velocity and vorticity field can be obtained quantitatively from experiments. This is demonstrated for the 3-D starting flow around a spherical cap at Re=300. During the starting process, the flow in the wake evolves into a spherical vortex ring where the velocity distribution is very close to the theoretical solution of the Hill-type vortex. Later on, the Hill-type vortex ring deforms and the flow changes from a rotational symmetric stage to a planar symmetric flow with a double-threaded vortical structure which consists of two counter-rotating streamwise vortices similar to the ones observed in sphere wake flow.

Rayleigh-Bénard convection in a small box: spatial features and thermal dependence of the velocity field

An experimental study of the spatial features of Rayleigh-Benard convection in a sall box is presented. Experiments are carried out in a rectangular cell (aspect ratios Γx = 2.03, Γy = 1.19) filled with silicone oil (Prandtl number, Pr = 130) for different Rayleigh numbers, Ra (up to Ra = 75Rac, Rac1707). The basic structure of the flow field for this range of Ra consists of two rolls with their axes parallel to the shorter horizontal side. Both senses of rotation for the rolls are observed, corresponding to the two branches of the bifurcation. Particle image velocimetry, with a 5 mW He-Ne laser as the illuminating source, is used to measure the velocity field in the midplane of the cell. From it the vorticity field (out of plane component) and two-dimensional streamlines are calculated. The flow has been measured to be three-dimensional, even for very low Ra, owing to the sidewall influence. The spatial features of the flow are shown to be dependent on both Ra and the sense of rotation of the rolls. Finally, a Fourier analysis of the velocity field is presented. The spatial and thermal dependences of the different Fourier terms are reported. The velocity field, in a first-order approximation, is quantitatively described.

Developments and applications of conjugate-wave holographic interferometry

Conjugate-wave holographic interferometry is an optical technique which was recently proposed by one of the authors for the measurement, in real time, of in-plane deformation. Basically, the technique consists of projecting, from two symmetrical directions, two real images of an object upon the object itself. If the object deforms, interference fringes are observed on its surface. These fringes give a representation of one in-plane component of the point displacement vector and are independent of the out of plane component. On this paper some aspects of the optical principles underlying the technique are analyzed in deeper detail, and more advanced solutions for their practical implementation are proposed. In addition, a few examples of applications on-plane and not-plane specimens are presented.

The Rotational Zeeman Effect of Pyrazole and Imidazole

The rotational Zeeman effect of the most abundant isotopic species of pyrazole and of imidazole has been studied under Δ M= 0 and Δ M = ± 1 selection rules. With field close to 1.9 Tesla, the nuclear Zeeman effect uncouples the rotational angular momentum and the spins of the two nonequivalent 14N quadrupole nuclei. The observed g-tensor elements are gaa = - 0.07498(14), gbb = - 0.12531(13), and gcc = 0.06346(12) for pyrazole and gaa = - 0.09339(16), gbb = - 0.10444(14), and gcc= 0.06051(15) for imidazole. The values for the magnetic susceptibility anisotropies in units of 10-6 erg/(G2 mol) are 2Xaa - Xbb - Xcc = 39.53(24) and 2Xbb - Xcc - Xaa = 51.20(21) for pyrazole and 2xaa - Xbb - Xcc = 45.76(31) and 2Xbb - Xcc - Xaa = 42.19(41) for imidazole. (Given uncertainties are single standard deviations of the fit.) The so-called nonlocal (π-ring current) contributions to the out of plane components of the susceptibility tensor Xcc nonlocal, derived as differences between the observed susceptibilities and values calculated from additivity rules for local atom susceptibilities, are compared to those derived earlier for other aromatic five membered ring molecules.

Using the circularly polarized components of synchrotron radiation for circular dichroism measurements between 400 and 3500 Å

The out of plane components of synchrotron radiation are circularly polarized to a high degree. This property offers the possibility to overcome the energy limitation of about 9 eV for circular dichroism (CD) and magnetic circular dichroism (MCD) measurements which is set by the optical components normally used to produce circularly polarized light. We report the first CD spectra which were taken using the circularly polarized components of synchrotron radiation. The light source was the Bonn 2.5 GeV synchrotron and a special monochromator constructed to monochromatize the off plane components of the radiation. Our experiments reveal several problems which make CD measurements very difficult. Some of these problems which we discuss in detail arise from the intrinsic properties of a synchrotron as compared to a storage ring but most are more general and have to be considered for further work on monochromators for the circularly polarized components of synchrotron radiation.

Rigid body motions in curved finite elements

D functions used to construct the stiffness matrix of a finite element should possess the following properties. 1) Infinitesimal rigid body motions should be accurately represented. If this requirement is not met the conditions of equilibrium of the element are not satisfied.*• 2) The displacement functions should contain all the lower terms of a complete set of functions. This requirement insures monotonic convergence by mesh size reduction. 3) A minimum degree of interelement continuity must be maintained between adjacent elements. This minimum degree of compatibility must insure a perfect match for the inplane and the out of plane components of displacement. Also for the out of plane component, slopes tangent and normal to all common edges of two adjacent elements must match. This requirement then insures convergence to an exact result by mesh size reduction. The importance of the last two requirements is firmly established; however, the first requirement has been shown to be problem dependent. If the structure to be analyzed is so constrained that no element of the structure is ever going to undergo any rigid body motion, then obviously this requirement can be violated. For example, axisymmetric elements acted upon by axisymmetric loads need to have only one rigid body mode: a rigid translation parallel to the axis of symmetry. For this particular type of element a truncated cone as used by Grafton and Strome always includes a rigid body motion parallel to the longitudinal axis. However, if the axisymmetric element is to have curvature in the longitudinal direction, then all the rigid body modes are absent. Jones and Strome recognized such a deficiency and reintroduced a longitudinal translation in their element. Later, Stricklin et al. reported on a similar improved element but omitted the longitudinal rigid body motion altogether. This last element is capable of handling asymmetric loading, therefore it is not difficult to imagine a loading in which many elements would have to undergo considerable transverse motion; a cantilevered structure would lead to such a situation. Haisler and Stricklin studied the influence of longitudinal translation and observed that such a rigid motion is recuperated by mesh size reduction. For elements of rectangular aspects, Bogner, Fox, and Schmit developed a systematic method for constructing acceptable displacement fields. However, for curved cylindrical elements, only two rigid body modes are accounted for. The same authors reported on a (48 X 48) stiffness matrix and mentioned that an eigenvalue analysis of such a matrix indicated that rigid body motions were adequately represented. However, as pointed out in our study of curved cylindrical elements, rigid body motions cannot be represented by independent displacement components. In the same reference, the importance of these rigid body motions is clearly illustrated in several examples. However, the inclusion of rigid body motions was done at the expense of rigorous interelement compatibility. This compromise resulted in a significant improvement in the behavior of the element. In this paper we develop a method to include rigid body motions without comprising deformational compatibility. The method is general and can be applied without difficulties to any element, curved or flat. The improvements of a curved cylindrical element are illustrated with one example.

Out-of-Plane Motion of a Stretched String under Forced Vibration

This paper treats the nonlinear phenomenon of out-of-plane motion that may develop under certain conditions in a stretched string subjected to planar forced vibrations. As in a previous paper dealing with the case of in-plane motion [J. Acoust. Soc. Am. (Dec. 1960)], the lack of inertial effects for longitudinal deformations occuring during transverse vibrations leads to tension levels that are uniform along the string but varying in time, and separable solutions are seen to result. In the course of the discussion, the out-of-plane motion is analyzed in terms of stability diagrams of Mathieu's equation, and results provide an interpretation of two types of out-plane motion, a “jump rope” mode (out of plane component 90° out of phase with in-plane component) and a “warped plane” mode (out of plane component in phase) which have been observed in experiments involving a slotted end constraint on the string. In the oral presentation, a motion picture sequence illustrating the characteristics of transverse vibration in an actual vibrating string will be presented.