Direction Of Major Axis Research Articles

Effect of Tabs on Rectangular Jet Plume Development

The near-field mixing performance of a rectangular jet with and without solid tabs introduced at the nozzle lip was studied under supersonic (underexpanded) operating conditions. The effects of tab shape, tab location, and tab number were investigated. Flow visualization of the jet plume was accomplished via Schlieren imaging, and the velocity and turbulence fields quantified via laser Doppler anemometry measurements. Laser Doppler anemometry data were gathered along the jet centerline and on cruciform transverse and spanwise traverse lines downstream of the nozzle exit. Tab shape has only a minor effect, however tab location and number are sensitive parameters for jet plume development. Tabs located on the nozzle wide edge can lead to jet bifurcation, whereas tabs located on the narrow edge cause increased mixing primarily in the major axis direction. A nozzle with four tabs located on its wide edges was the most effective for overall enhancement of jet mixing.

Thermomechanical Property of Rice Kernels Studied by DMA

The thermomechanical property of the rice kernels was investigated using a dynamic mechanical analyzer (DMA). The length change of rice kernels with a loaded constant force along the major axis direction was detected during temperature scanning. The thermomechanical transition occurred in rice kernels when heated. The transition temperatures were determined as 47°C, 50°C and 56°C for the medium-grain rice with the moisture contents of 18.1%, 16.0% and 12.5% (wet basis), respectively. Length change of the rice kernels increased with the increase of the temperature and moisture content. Among the four rice varieties investigated, the results showed that the thermomechanical property was not significantly affected by variety.

The kinematics of the Seyfert 2 galaxy NGC 5728 circumnuclear region

We secured spectral images of the circumnuclear, 12 x 10 arcsec 2 region of the Seyfert 2 galaxy NGC 5728 with the Optically Adaptive System for Imaging Spectroscopy at the Canada-France-Hawaii Telescope 3.6-m telescope. The radial velocity distribution of the two bright zones, main central (C) core and north-west (NW) core, and strategically important points along the position angles, PA 33°, 90°, 123° and 143°, are analysed. The large-scale reconstructed monochromatic images of the Ha, Hβ, [OIII] and [NII] lines show a bipolar morphology along PA ∼ 123°. The prominent elliptical ring is seen in the Ha and Hβ monochromatic images. Our analysis implies that this ring is rotating in the same clockwise direction as that of the galactic disc; this elliptical ring is in fact a projected result of a circular ring of radius ∼5.4 arcsec, with i ∼ 50° (nearly aligned with the host galactic plane). We used the [O III]5007 line profiles for a detailed analysis of kinematics in the circumnuclear region of the NGC 5728. The [O III]5007 line profiles reveal distinct kinematical structures. (1) The strongest component of Doppler peaks: two core components, consisting of the receding main C-core and the approaching NW-core with the radial velocities, V r ≃ +250 and -240 (or -250) km s -1 , respectively. These two cores consist of a roughly spherically symmetric distribution of the gas with radii of r ∼ 1.0 arcsec (at V r ≃ +240 km s -1 ) and 0.9 arcsec (at V r ≃ -240 km s -1 ), respectively. Hints of the presence of inflows around these cores are observed. (2) The next strong line profile component: this component corresponds to the bipolar cone aligned PA ∼ 123°. (3) The reverse S-shaped kinematical boundary which runs through the double-peaked zone of 6-7 arcsec long in the galactic major axis direction is likely to be caused by a combination of the disc rotation of the host galaxy and the revolution of the two central cores.

Textual research of 1219 A.D. Guyuan earthquake in Ningxia Hui autonomous region, China and discussion on its causative structure

On the basis of textual research on the historical earthquake data and the field investigation of 1219 A.D. Guyuan earthquake, we suggest that there is only one strong earthquake occurred in Guyuan area in 1219 A.D., instead of two or three strong earthquakes. We further suggest that the earthquake parameters recorded in the present earthquake catalogs are not definite and should be modified. The occurrence time of this earthquake should be about 11 am, August 7, 1219 A.D. and the heavily-damaged area of this earthquake, the VIII intensity area, should be located among the regions of Guyuan, Pingliang and Longde county cities. The epicenter area should be near Guyuan city. The magnitude of this earthquake is about 7 and it has intensity about larger than or equal to IX within the epicenter area. The major axis direction of the heavily-damaged area strikes in north-northwest that is approximately consistent with the strike of the Liupan Shan thrust fault zone. The new tectonic activity of the Liupan Shan thrust fault zone resulted in the M7 Guyuan earthquake in 1219 A.D.

The role of seismic methods in investigation of rock mass

The existence of cracks in a rock mass causes the reduction of seismic wave velocity and the anisotropy of seismic wave velocity, which is characteristic for rocks with preferred orientation of cracks. The present study concerns sedimentary rocks (sandstone, limestone) and igneous rocks (basalt, granite). Studying the relationship between seismic anisotropy and cracks anisotropy in rocks I was only interested in fractures perpendicular to the layering. This allowed me to calculate two-dimensional crack tensors and velocity tensors in planes parallel to the layer surface. An application of tensor calculus enables to take into account both geometry and orientation of cracks. The obtained results confirm that the directions of major axes of second-rank velocity tensor prove the relationship consistent with predictions of theoretical models. Owing to these dependences, seismic methods can be used to study the cracks anisotropy in rocks inaccessible for direct observations.

Structural Capacities of Tension Side for CFT Square Column-To-Beam Connections with Combined-Cross Diaphragm

The purpose of this study is to suggest a new CFT column-to-beam connection type, which will have an axis direction that takes into consideration the asymmetry of connections. Through experimental study and finite element analysis, the study also compares the structural capacities of the new CFT column-to-beam connection type with those of existing connection types. Existing connection types for comparative study are those with an interior diaphragm and through diaphragm. The new connection type suggested uses a combined-cross diaphragm, featuring a column flange penetration in the major-axis direction and an interior diaphragm in the minor-axis direction. In order to analyze and compare the initial stiffness and strengths of the connections considered simple tension tests along with finite element analysis were performed on the specimens, while idealizing the tension-applied beam flange. Stress concentrations, according to the geometric configurations and load transfer mechanisms of diaphragms, were analyzed through finite element analysis. The results show that the existing connection types, in terms of initial stiffness and ultimate strength, do not precede the combined-cross diaphragm, and that the stress concentration on the connection can be relieved by improvement to the detail.

Textual research of Wudu earthquake in 186 B.C. in Gansu Province, China and discussion on its causative structure

On the basis of the textual research on the historical earthquake data and the field investigation of Wudu earthquake occurred in 186 B.C., we suggest that the earthquake parameters drawn from the present earthquake catalogs are not definite and amendments should be made. The heavily-damaged area of this earthquake should be located between Jugan township of Wudu County and Pingding township of Zhouqu County. Its epicenter should be in the vicinity of Lianghekou in Wudu County with a magnitude of about 7∼7¼ and an intensity of about IX∼X. The major axis direction of the heavily-damaged area should be in the WNW direction that is approximately consistent with the strike of the middle-east segment of Diebu-Bailongjiang active fault zone, and the origin time should match up to that of the latest paleoearthquake event [before (83±46) B.C.] obtained by the trench investigation. Certain seismic rupture evidences are still preserved on this fault segment. Therefore, we propose on the basis of comprehensive analysis that the causative structure of the M 7∼7¼ Wudu earthquake in 186 B.C. should be in the middle-east segment of Diebu-Bailongjiang active fault zone.

Fourier Representation of Quadratic Friction

Abstract If a current is composed of a number of constituents with different frequencies, then quadratic friction may be analyzed at the same frequencies. The ratios of the constituents of the friction differ from the ratios for the current itself, with a classic result being that for unidirectional flow a very weak current constituent experiences proportionately 50% more friction than a strong constituent. Here, exact results for the magnitude of the friction constituents are derived and confirmed numerically. The results are applied to the tidal currents in Juan de Fuca Strait and the Strait of Georgia, showing that minor constituents experience proportionately more friction than the main constituent by an amount that varies spatially but is typically less than the classic result of 50%. For two-dimensional currents it is shown that, if there are two current constituents with the same ellipticity and major axis direction, the friction coefficients are separable functions of the current constituent ratio and the ellipticity. Some results are derived for two constituents with different ellipticity and major axis direction. For the case of two constituents with rectilinear but misaligned currents, each constituent experiences friction inclined at an angle to its current. Last, the effect of a tidal current on the bottom friction experienced by a steady flow is investigated for arbitrary relative magnitudes and directions of the tide and steady flow. In particular, the inclination of the mean friction to the mean flow is quantified.

A simple method for fitting of bounding rectangle to closed regions

In this paper, we introduce a new approach for fitting of a bounding rectangle to closed regions. In this approach the coordinates of the vertices are computed directly using a closed-form solution. This approach is based on simple coordinate geometry and uses the boundary points of regions. Using a least-square approach we determine the directions of major and minor axes of the object, which gives the orientation of the object. The four vertexes of the bounding rectangle are computed by pair wise solving the four straight lines. Examples from synthetic data and some real-life data show that the approach is both accurate and efficient.

Experimental study on seismic performance of concrete filled tubular square column-to-beam connections with combined cross diaphragm

The connection with combined cross diaphragm is developed for the connection of square CFT column and steel beam and proposed to be used for the frame with asymmetric span length. The structural characteristics of this connection lie in the penetration of the beam flange in the direction of major axis through the column for the smooth flow of stress. The purpose of this study is to analyze the dynamic behavior and stress flow of suggested connection and to evaluate the resistance to shock of connection. Four T-type CFT column-to-beam specimens; two with combined cross diaphragm and the others with interior and through diaphragms, the existing connection types, were made for cyclic load test guided by the load program of ANSI/AISC SSPEC 2002. The results show that the proposed connection is more efficient than existing ones in terms of strength, stress flow and energy absorption and satisfies the seismic performance required in the region of weak/moderate earthquakes.

Gemini/GMOS Integral Field Unit stellar kinematics of the nuclear region of six nearby active galaxies

We present 2D mapping of the stellar velocity field within the inner 5 arcsec of six nearby active galaxies, using spectra obtained with the Integral Field Unit (IFU) of the Gemini Multi-Object Spectrograph instrument at the Gemini North telescope. The sampling of the observations is 0.2 arcsec, corresponding at the galaxies to spatial extents ranging from 10 to 30 pc. The spatial resolution range from 20 to about 180 pc, and the observed field of view covers a few hundred parsecs around the nuclei. The Can triplet absorption features at ≈8500 A were used to measure the stellar radial velocities and velocity dispersions. The radial velocity fields are dominated by rotation in all galaxies. A simple kinematical model assuming a purely rotating system with circular orbits in a plane was fitted to the radial velocity data. The turnover of the rotation curve is at only ≈50 pc for NGC 4051 and between 200 and 700 pc for the other five galaxies. The velocity dispersion (σ) maps show the largest values (100 ≥ σ ≥ 150 km s -1 ) at the centre. In the cases of NGC 2273 and 3227, there is a decrease to σ ≈ 70-80 km s -1 at ≈200-300 pc from the nucleus, delineating partial rings of low-σ values. A similar broken ring seems to be present at ≈400 pc from the nucleus also in NGC 4593. We interpret these low-σ rings as traces of recently formed stars that partially keep the cold kinematics of the original gas from which they have formed. In NGC 3516 there is a decrease of σ outwards with the steepest gradient observed along the direction of the galaxy major axis, where σ reaches ≈80-90 km s -1 at ≈400 pc from the nucleus. The main novelty of the present work is the unprecedented spatial resolution reached by a 2D study of stellar kinematics of Seyfert galaxies using an IFU. The few similar IFU studies available in the literature for Seyfert galaxies have a much poorer spatial resolution and/or are restricted to the study of emission-line kinematics.

Effect of elastohydrodynamic film thickness on a wear model for worm gears

Worm gears used for power transmission commonly consist of a steel worm running against a bronze or phosphor bronze worm wheel. The wheel teeth are usually manufactured using an ‘oversize’ hob so that the initial elastic contact between the teeth is in the form of an ellipse with lubricant entrainment predominantly in the major axis direction. As a result of this unfavourable contact geometry, the lubricant film generated between the worm and wheel teeth is relatively thin. The kinematic configuration is close to that of simple sliding as the velocity of the wheel tooth surface relative to the nominal contact point is very low in comparison with that of the worm. The combination of poor film forming, high sliding and a soft gear material (to avoid scuffing) leads to the continuous wear seen in these gears. The article presents results obtained using a model for the prediction of wear for this configuration based on the well-known Archard wear law extended to take the variation of pressure and film thickness over the contact area into account in determining the wear rate. The pressure and film thickness distributions are obtained from elastohydrodynamic lubrication (EHL) modelling of the contact over the meshing cycle. Wear patterns are presented corresponding to different film thickness sensitivities in the wear formula, and these predictions, together with the calculated increase in backlash due to wear, give a basis for calibrating the model against experimental wear tests.

Influence of pad shape on self-alignment in electronic packaging

Anisotropic self-alignment of the noncircular pads is investigated to reduce the misalignment in electronic packaging, and the effects of the direction and length ratio of the noncircular pads are analyzed. The restoring forces of circular and noncircular pads are calculated numerically using the surface evolver and are compared with the experimental data. The restoring force in the minor-axis direction of the noncircular pad becomes largest followed by the circular pad and the major-axis direction of the noncircular pad. Directionality increases with the length ratio, which implies that more accurate alignment can be achieved in the specific direction.

Axis switching in turbulent buoyant diffusion flames

Dynamics of buoyant diffusion flames from rectangular, square, and round fuel sources were investigated using direct numerical simulation (DNS). Fully three-dimensional simulations were performed employing high-order numerical methods and boundary conditions to solve governing equations for variable-density flow and finite-rate Arrhenius chemistry. Significant differences among the different cases were revealed in the vortex dynamics, entrainment rate, small-scale mixing, and consequently flame structures. Mixing and entrainment enhancement in non-circular flames in comparison with circular ones was explained using the Biot–Savart instability theory, which relates vortex dynamics to the local azimuthal curvature. An extension of the theory elucidated why rectangular flames entrain more efficiently and spread wider than square ones, although both configurations have corners. It also provided an explanation for the aspect ratio effects in the near field. In the far field, nonlinear effects were dominant and the general transport equations for vorticity were analyzed in detail. The corner effects and aspect ratio effects were shown to be augmented by the intricate interactions among vortex dynamics, combustion, and buoyancy through the various terms in the equations. The presence of corners in non-circular flames led to concentrated regions of fine-scale mixing and intense reactions centered around the corners. Moreover, the rectangular flames exhibited a different dynamic behavior from even the square one, by creating discrepancies in entrainment, mixing, and combustion between the minor and major axis directions. Increasing the aspect ratio exacerbated such directional discrepancies, and ultimately led to axis switching. It was the first time that axis switching was observed by DNS in a rectangular flame of aspect ratio 3, which raised further questions in combustion prediction and control. Finally, a unified explanation for corner and aspect ratio effects was given on the basis of the Biot–Savart instability theory and the vorticity transport equations.

3D Hierarchical orientation in polymer–clay nanocomposite films

Organically modified clay was used as reinforcement for HDPE using maleated polyethylene (PEMA) as a compatibilizer. The effect of compatibilizer concentration on the orientation of various structural features in the polymer-layered silicate nanocomposite (PLSN) system was studied using two-dimensional (2D) small angle X-ray scattering (SAXS) and 2D wide-angle X-ray scattering (WAXS). The dispersion (repeat period) and three-dimensional (3D) orientations of six different structural features were easily identified: (a) clay clusters/tactoids (0.12 μm), (b) modified clay (002) (24–31 Å), (c) unmodified clay (002) (13 Å), (d) clay (110) and (020) planes normal to (b) and (c), (e) polymer crystalline lamellae (001) (190–260 Å), and (f) polymer unit cell (110) and (200) planes. A 3D study of the relative orientation of this hierarchical morphology was carried out by measuring three scattering projections for each sample. Quantitative data on the orientation of these structural units in the nanocomposite film is determined through calculation of the major axis direction cosines and through a ternary, direction-cosine plot. Surprisingly, it is the unmodified clay which shows the most intimate relationship with the polymer crystalline lamellae in terms of orientation. Association between clay and polymer lamellae may be related to an observed increase in lamellar thickness in the composite films. Orientation relationships also reveal that the modified clay is associated with large-scale tactoid structures.

Tidal Currents in the Tsushima Straits Estimated from ADCP Data by Ferryboat

Tidal currents in the Tsushima Straits have been analyzed using measurements obtained since February 1997 by an acoustic Doppler current profiler (ADCP) mounted on the ferryboat Camellia. Tidal current constituents (M 2, S 2, K 1, O 1) are dominant among the ten tidal current constituents (Q 1, O 1, P 1, K 1, N 2, M 2, S 2, K 2, MSf, Mf), and generally 1.4–2.1 times stronger at the western channel of the straits than those at the eastern channel. The ratio between amplitude of M 2, S 2, K 1 and O 1 averaged along the ferryboat track is 1:0.45:0.59:0.51. The major axis directions of tidal current ellipses are generally SW to NE, exceptionally in the vicinity of the Tsushima Islands. Approaching the Tsushima Islands from the Korean Peninsula side, the major axis gradually rotates clockwise. At the western channel, the M 2 and K 1 constituents change the rotation direction of current vectors from clockwise to counterclockwise at about 90–130 m depth. The contributions of the tidal currents to the mean kinetic energy and the mean eddy kinetic energy along the ferryboat track are, on average, 0.56 and 0.71, respectively. This suggests that tidal current activities are generally more dominant than the mean current activities and much more dominant than eddy activities. The only region where the eddy activities are comparable to the tidal current activities is located on the east side of the Tsushima Islands.

Whisker-Like Goethite Nanoparticles Containing Cobalt Synthesized in a Wet Process

Acicular α-FeOOH particles are formed through aging of ferric oxyhydroxide colloidal solution formed by the neutralization of FeCl 3 aqueous solution by NaOH. The effects of cobalt ion addition in the sol-gel-sol process on the formation rate and morphology of α-FeOOH nanoparticles have been investigated. The magnetic properties of metal nanoparticles prepared from the obtained particles have also been examined. The dependence of reaction rate constants in the formation of α-FeOOH in the wet process and the crystallite size of (110) on Co content in α-FeOOH has been made clear. Both the rate constant and crystallite size decrease with increasing Co content in α-FeOOH particles. The negative zeta-potential of the formed α-FeOOH particles increases slowly with increasing pH of the electrolytic solution. The negative zeta-potential of α-FeOOH particles containing Co is larger than that of α-FeOOH particles without Co in the range of pH6-pH12. The relationship between the morphology of the formed α-FeOOH particles and the cobalt content in α-FeOOH particles has been investigated. The length of major axis increases and the length of minor axis decreases with increasing Co content, and the aspect ratio increases remarkably. It is likely that Fe(OH) - 4 complex ion precipitates preferentially on the c plane, and the particles grow remarkably in the direction of c axis. The interplanar spacing of the α-FeOOH decreases with increasing Co content. The formed α-FeOOH grows abnormally like whisker in the direction of major axis: c axis in the case of significantly much Co content: 27 at%, and also the whisker like nanoparticles are observed to grow with curving. The magnetic metal nanoparticles produced have excellent dispersivity and high aspect ratio. The metal nanoparticles have magnetic properties enough for the magnetic recording media.

Dynamic interfacial properties of polymer blends under large step strains: shape recovery of a single droplet

We observed shape recovery of a deformed droplet in an immiscible polymer matrix under large step strains using stereo microscopes from two directions. On application of a large step strain, a soft spherical droplet in a matrix with higher viscosity deformed to a flat ellipsoid. The stretch ratio of major axis of the flat ellipsoid was 5/4 times larger than that predicted from the affine deformation. The flat ellipsoid changed into a rod-like shape and then to a dumbbell, to an ellipsoid of revolution, and finally back to the sphere. The orientation angle between the major axis and shear direction did not change during the course of this shape recovery and was independent of the initial radius of the droplet. The time needed for the whole shape recovery got longer as the initial radius and the strain were increased. For a given step strain, the normalized interfacial area plotted against the stretch ratio fell onto a master curve irrespective of the initial radius of the undeformed droplet. It is shown that the deformed droplet reforms to the sphere after it passes through various shapes by reducing the interfacial area.

Film thickness predictions for elastohydrodynamic elliptical contacts over a wide range of radius ratios with consideration of side starvation

The paper presents numerical solutions obtained for a wide range of elliptical elastohydrodynamic lubrication (EHL) problems. The conditions considered encompass relative principal radii of curvature ratios from 20:1 with entrainment in the minor axis direction, to 50:1 with entrainment in the major axis direction. The problems considered derive from investigations of practical machine elements where the width of contact (perpendicular to entrainment) is limited by the extent of the metal surfaces on either side. Two sets of results have been obtained: one with the width of the lubricated contact approximately twice that of the Hertzian dry contact, and the other where the ratio of these widths is 1.2. Taken as a whole the results present a complete range of conditions obtained using the same numerical model throughout. The film thickness predictions are compared with those given by well-known published formulae and design charts.

Effects of Cell Geometry on the Compressive Properties of Nickel Foams

The compressive properties of three kinds of nickel foams with different cell sizes were investigated. The stress—strain curves showed a plateau region. The cell size had a minor influence on the plateau stress when the stress was normalized with the relative density and the yield stress of the cell edge material. Compressive tests were also performed under loading conditions along different axes in the foam with elliptical cells. As a result, the foam was stronger for loading in the major axis direction, compared with in the minor axis direction. Therefore, it has been demonstrated that the cell aspect ratio produces a certain influence on the plateau stress of foam, whereas the cell size appears to have a negligible effect.