Small Orientation Angles Research Articles

The Influence of Tank Orientation Angle on a 2D Structure-Tuned Liquid Damper System

Tuned liquid dampers (TLDs) utilize sloshing fluid to absorb and dissipate structural vibrational energy, thereby reducing wind induced dynamic motion. By selecting the appropriate tank length, width, and fluid depth, a rectangular TLD can control two structural sway modes simultaneously if the TLD tank is aligned with the principal axes of the structure. This study considers the influence of the TLD tank orientation on the behavior of a 2D structure-TLD system. The sloshing fluid is represented using a linearized equivalent mechanical model. The mechanical model is coupled to a 2D structure at an angle with respect to the principal axes of the structure. Equations of motion for the system are developed using Lagrange’s equation. If the TLD and structure are not aligned, the system responds as a coupled four degree of freedom system. The proposed model is validated by conducting structure-TLD system tests. The predicted and experimental structural displacements and fluid response are in agreement. An approximate method is developed to provide an initial estimate of the structural response based on an effective mass ratio. The results of this study show that for small TLD orientation angles, the performance of the TLD is insensitive to TLD orientation.

Phase-difference of urban area in polarimetric SAR images

Proposed is a new phase-difference parameter for classifying urban areas in a polarimetric SAR image. First, the phase-difference characteristics of urban areas was analysed for various orientation angles. Subsequently it was found that the co-polarised phase-difference (CPD) is adequate for an aligned urban area, while the cross-polarised phase-difference (XPD) is the best parameter for a 45°-oriented urban area. Based on these analyses, the CPD was used for a small orientation angle (|thetas|≤π/8) and the XPD for a large orientation angle (|thetas|>π/8) to improve the accuracy of the urban classification in a polarimetric SAR image. This new technique was verified using polarimetric SAR image data sets (PALSAR and RADARST-2 images).

Fusion-fission and quasifission competition in the 32S+184W reaction

The angular distribution of fission fragments for the 32S+184W reaction at center-of-mass energies of 118.8, 123.1, 127.3, 131.5, 135.8, 141.1 and 144.4 MeV were measured. The experimental fission excitation function is obtained. The fragment angular anisotropy is found by extrapolating the fission angular distributions. The measured fission cross sections are decomposed into fusion-fission, quasifission and fast-fission contributions by the dinuclear system model. The total evaporation residue and fusion-fission excitation functions are calculated in the framework of the advanced statistical model. The hindrance to complete fusion at small collision energies increases due to the increase of quasifission events and it is explained by the elongated shape of the dinuclear system which is formed in collisions with small orientation angles to the beam direction. An increase of the hindrance to complete fusion at large beam energies is explained by the dependence of the quasifission and intrinsic fusion barriers of dinuclear system on its angular momentum: at large angular momentum the quasifission barrier decreases and the intrinsic fusion barrier increases. In this reaction the contributions of fusion-fission and quasifission fragments are comparable.

Is All Anterior Oblique Fracture Orientation Really a Contraindication to Anterior Screw Fixation of Type II and Rostral Shallow Type III Odontoid Fractures?

It is debatable whether an anterior oblique fracture orientation is really a contraindication to anterior odontoid screw fixation. The purpose of this study was to investigate the feasibility of anterior odontoid screw fixation of type II and rostral shallow type III fracture with an anterior oblique fracture orientation. The authors evaluated 16 patients with type II and rostral shallow type III odontoid fracture with an anterior oblique fracture orientation. Of these 16 patients, 8 (group 1) were treated by anterior odontoid screw fixation, and 8 (group 2) by a posterior C1-2 arthrodesis. Of the 8 patients in group 1, seven patients achieved solid bone fusion (87.5%), and one experienced screw back-out of the C-2 body two months after anterior screw fixation. All patients treated by posterior C1-C2 fusion in group 2 achieved successful bone fusion. Mean fracture displacements and fracture gaps were not significantly different in two groups. (p=0.075 and 0.782). However, mean fracture orientation angles were 15.3±3.2 degrees in group 1, and 28.6+8.1 degrees in group 2 (p=0.002), and mean fragment angulations were 3.2±2.1 degrees in group 1, and 14.8±6.7 degrees in group 2 (p=0.001). Even when the fracture lines of type II and rostral shallow type III fractures are oriented in an anterior oblique direction, anterior odontoid screw fixation can be feasible in carefully selected patients with a relatively small fracture orientation angle and relatively small fragment angulation.

Combined Analytical and Finite Element Beam Model for Wind Turbine Blades

Finite element method (FEM) has been widely used in recent years to analyze fiber-reinforced polymer (FRP) beams such as wind turbine blades. Although it is generic and convenient, FEM does little to shed light on the mechanical behavior of structures. Moreover, it is inefficient in calculation. This study presents a combined analytical and finite element beam (CAFB) model with an inclination angle correction to solve the non-prismatic, blade-like FRP beam problem. It not only substantially reduces computational time, but also helps us comprehend the mechanical behavior. Also, the inclination angle correction is supposed to correct the overestimated axial stiffness due to the topology of beams. In the presented cases, the CAFB model can accurately analyze the FRP thin-walled beams with all results being certified by finite element analysis software, and the correction is especially effective in small fiber orientation angles.

Competition between fusion-fission and quasifission processes in 32S+ 184W reaction

The angular distributions of fission fragments for the 32S+ 184W reaction at center-of-mass energies of 118.8, 123.1, 127.3, 131.5, 135.8, 141.1 and 144.4 MeV were measured. The fragment angular anisotropies are found by extrapolating the fission angular distributions. The measured fission cross sections are decomposed into fusion-fission, quasifission and fast-fission contributions by the dinuclear system model. The hindrance to complete fusion at small collision energies increases due to the increase of quasifission events and it is explained by the elongated shape of the dinuclear system which is formed in collisions with small orientation angles to the beam direction. An increase of the hindrance to complete fusion at large beam energies is explained by the dependence of the quasifission and intrinsic fusion barriers of dinuclear system on its angular momentum. In this reaction the contributions of fusion-fission and quasifission fragments are comparable.

Role of structure and morphology in the elastic modulus of carbon nanotube composites

The nature of nanoscale reinforcements in the carbon nanotube composites indicates nanocomposite properties are heavily dependent on the micro/nano-structure and morphology. Macroscopic parameter-based properties estimation may lead to deviation as large as 30%. In this paper, a modified shear-lag model, combined with probability statistical theory and composites morphology, is established to investigate the elastic properties of single wall carbon nanotubes (SWNTs)-reinforced polymer composites. The computational results indicated that elastic modulus of nanocomposite was remarkably dependent on the micro/nano-structure, including diameter, length, and orientation of the dispersed SWNTs. Microstructure-dependent shape factor and orientation effect factor played a key role on achieving high-performance nanocomposites. Elastic modulus of nanocomposite with well-dispersed carbon nanotubes was more susceptible to the orientation. Similarly, nanocomposite modulus was more subject to the dispersion influence when SWNTs were well-aligned. The maximal modulus was located in the zone of small rope diameters and small orientation angles when adequate interfacial bonding was provided. The computational results were also compared with experimental outcome and demonstrated good consistence.

Aniline on Ag(1 1 1): Adsorption configuration, adsorbate–substrate bond, and inter-adsorbate interactions

The adsorption of submonolayer aniline on the Ag(1 1 1) surface has been characterized using temperature programmed desorption (TPD) and electron energy loss spectroscopy (EELS). Analysis of the TPD curves yielded a desorption energy of 74 kJ/mol and revealed repulsive inter-adsorbate interactions resulting from a local dipole moment of 4.3 D at the adsorbate–substrate complex. This dipole moment arises from a weak charge transfer from aniline to silver in forming the adsorption bond. Analysis of the EELS spectrum revealed several vibrational modes that are consistent with weakly chemisorbed aniline with the amino group bound to the surface. Intensity analysis based on IR selection rules on metal shows that the molecule adsorbs nearly flat with a small tilt angle (−13 ± 8° between the CN bond and the surface) and a small orientation angle.

A new proposal for polymer dynamics in steady shearing flows

Beginning with a recently proposed expression for the drag force on a single macromolecule pulled with constant velocity through a fluid of long-entangled molecules (V. R. Mhetar and L. A. Archer, Macromolecules 1998, 31, 6639), we investigate the effect of entanglement loss on polymer dynamics in steady shearing flows. At steady-state, a balance between the elastic restoring force and viscous drag acting on entangled polymer segments reveals a critical molecular strain γm,c beyond which the drag force exerted on polymer molecules by their neighbors is insufficient to support arbitrarily small orientation angles. Specifically, we find that in fast steady shear flows τ < γ˙ < τ, polymer orientation in the shear plane approaches a limiting angle χc ≈ atau(1/(1 + γm,c)) beyond which flow becomes incapable of producing further molecular alignment. Shear flow experiments using a series of concentrated polystyrene/diethyl phthalate solutions with fixed entanglement spacing, but variable polymer molecular weight 0.94 × 106 ≤ Mw ≤ 5.48 × 106, reveal a limiting steady-state orientation angle between 6° and 9° over a range of shear rates; confirming the theoretical result. Orientation angle undershoots observed during start-up of fast steady shearing flows are also explained in terms of a transient imbalance of elastic restoring force and viscous drag on oriented polymer molecules. Our findings suggest that the Doi–Edwards affine orientation tensor (Q) is not universal, but rather depends on deformation type and deformation history through a balance of elastic force and viscous drag on polymer molecules. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 222–233, 2000

Design Methodology for Braided Composite Tubes. 1st Report. Bending Properties.

The design methodology for braided composite tube was proposed. The weaving structures such as fiber orientation angle and crimp ratio of fiber largely affect the mechanical properties of braided composites, thus the analytical model has to represent faithfully the weaving structures. Therefore the analytical procedure involved the use of models from micro model to macro model. This method was applied to estimate flexural rigidity and initial fracture stress of braided tube under bending load. The flexural rigidity decreased with increase of fiber orientation angle, which was the angle formed between the fiber bundles and the fabric axis. The flexural rigidity was enhanced by middle-end-fiber and the effect varied with the location of middle-end-fiber. The position at which initial fracture occurred was changed depending on the fiber orientation angle. In the case of small fiber orientation angle the initial fracture stress depended on the strength of the cross resin element, so that the initial fracture stress was not always enhanced by the middle-end-fiber.

Electric birefringence at small analyzer orientation angles

Electric birefringence at small analyzer orientation angles

An ultrasonic orientation sensor with distributed receivers

This paper is concerned with an ultrasonic orientation sensing system, which measures the orientation of an objective surface, using the phase information of the reflected echoes. At least two phase differences obtained from three receivers are necessary to determine the three-dimensional orientation. However, the phase difference cannot be distinguished over one period of the reflected echo. Hence, the measuring range is restricted to a relatively small orientation angle. In this paper, a method is proposed to overcome the difficulty by increasing the number of receivers. Closely arranged receivers encircling a transmitter can provide a smaller difference between adjacent reflecting paths. They keep the individual phase difference to a sufficiently small value and allow measurement of the orientation over a wide range. This paper shows the principle of measuring two directional angles of a surface normal based on the least-squares method. The redundant phase information obtained by the many receivers als...

Real-time 'computer-evaded' pseudo-holography of computed tomography images.

An off-line method of dynamic imaging has been developed to facilitate visualization of three-dimensional tomographic data during real-time manoeuvres. Stereo-pair projection of multiple contiguous cross-sectional images on a conventional 625 line 50 Hz television raster has been investigated and pseudo-holograms have been displayed. A Cartesian stereo-pair projection model incorporating three degrees of rotational freedom and perspective has been developed. Computer simulations of the model have been conducted and the feasibility of adopting a simplified model has been examined. A condensed solution with two degrees of freedom, retaining partial perspective effects, has been simulated and analysed for worst-case errors. Reasonable projection accuracy has been demonstrated for small orientation angles. Specialized display hardware has been developed and a departure has been made from conventional picture-element (pixel) display methodology. Elemental quadrilaterals (rho-pixels), varying in size, shape and screen position, have been considered as an alternative to static square pixels in a rigid matrix. Joystick-controlled rho-pixel arrays have been implemented with parallelogram-shaped rho-pixels incorporated as a simplified case of quadrilateral projection. Dynamic stereo-pair projections of 64 X 64 rho-pixel arrays have been generated from computed tomography (CT) images and the results of phantom studies on a four-plane system are discussed.

分布型受信器をもつ姿勢計測用超音波センサ

This paper is concerned with an ultrasonic orientation sensing system, which measures the orientation of an objective surface, using the phase information of the reflected echoes. At least two phase differences obtained from three receivers are necessary to determine the three-dimensional orientation. However, the phase difference cannot be distinguished over one period of the reflected echo. Hence, the measuring range is restricted to a relatively small orientation angle. In this paper, a method is proposed to overcome the difficulty by increasing the number of receivers. Closely arranged receivers encircling a transmitter can provide a smaller difference between adjacent reflecting paths. They keep the individual phase difference to a sufficiently small value and allow measurement of the orientation over a wide range. This paper shows the principle of measuring two directional angles of a surface normal based on the least-squares method. The redundant phase information obtained by the many receivers als...

紙のカール ＩＩ カール近似公式の誘導とその適用性

Approximate formulas for predicting reversible curl behavior have been derived from the lamination theory of curl, which was developed by Carlsson.Paper sheet is considered here as a laminate which consists of “wire” side and “felt” side sheet having equal thickness and different properties. If difference in elastic constants of both sides is small as compared with their average values over the thickness, curvature equation in the lamination theory is systematically approximated, as described in Appendix I. For relatively small orientation angles, the formulas are expressed as eqs.(1) through (3), which include expansion coefficients, orientation angles, moisture (or temperature) changes and thickness as main parameters. The formulas revealed that bending curl is mainly determined by the difference in expansion coefficients of both sides, while twisting curl is strongly dependent on the orientation angle and the degree of anisotropy.The validity of the formulas has been established through numerical comparison with the exact solutions. It was found that the bending curvature can be described even by the first term of the formula for the case of small orientation angles or weak anisotropy. In order to determine applicability of the two-layer model for the case of real sheets, fine paper samples were ground by using a specially designed surface grinder to obtain wire and felt side sheets, and expansion coefficients and orientation angles were determined for each side to predict the curvature components by using the curl formulas. A general agreement has been found between measured and predicted curl changes.

Please Remain Seated: Seat Designs to Help Retain Passengers during Emergency Stops

A series of experiments were conducted to identify the factors that could aid passengers in remaining seated during an emergency deceleration of an automated transit system. Sixty subjects, representative of three anthropometric levels, underwent various levels of deceleration in an instrumented vehicle controlled by an automated braking system. The independent variables examined were seat orientation and tilt, seat contour and covering, footrests and armrests, and rate of change of deceleration (jerk). The primary dependent variables were the deceleration levels at which subjects moved from sensors that were imbedded in the experimental seat. Movies were taken and subject comfort ratings were also obtained. The major results indicated that forward-facing subjects sustained higher deceleration levels without being dislodged than subjects sitting at small orientation angles of 15° and 30°. A foot-rest contributed to greater retention of forward-facing subjects as did a seat tilt of 12° back. The maximum deceleration level for retention of 84 percent of the forward-facing passengers sitting on a seat tilted back 12° and using a footrest was 0.36 g. Jerk was found not to be a factor in dislodging subjects during the onset of the emergency stop. It was, however, a factor in the perception of comfort. Subjects reported being more uncomfortable at higher jerk levels. Providing a warning to the passengers of an impending stop may aid them in sustaining higher deceleration levels.