Angular Shift Research Articles

Optimizing the strength of the Bourdon effect by varying the triangle arrangement.

The Bourdon illusion refers to the perceived bentness of the straight collinear edges when two right-angled triangles are placed apex to apex. We studied this illusion using a cancellation method. In the first of three experiments, we manipulated the apex angle, with six different angles ranging from 4° to 45°. Results indicated that the Bourdon illusion is strongest when the angle is around 12°. In the second experiment, we compared four scalene triangles with a right-angled triangle. The angular shift was most salient when the shape corresponded to a right-angled triangle. In the third experiment, the patterns were created by varying the size of one right-angled triangle while holding the size of the second right-angled triangle constant. Results indicated that the Bourdon illusion was strongest when both right-angled triangles were of equal size. Our data suggest that the Bourdon illusion depends critically upon the specific arrangement of shapes in the display.

Quantized Goos-Hänchen shifts on the surface of hybridized topological insulator thin films

We study the Goos-Hänchen (GH) shift from the surface of a hybridized topological insulator (TI) thin film in the presence of a static magnetic field. We impinge a circularly polarized Gaussian beam on TI thin film substrate and calculate the lateral and angular GH shifts under partial reflection conditions. We show that magnetic field modulated giant positive and negative quantized spatial and angular beam shifts can be obtained by tuning the angle of incidence in the vicinity of Brewster angle and frequency in the terahertz regime. We also investigate the GH shifts in different topological phases of the TI thin film by driving the system through several topological quantum phase transitions (TQPTs), i.e., from topologically nontrivial to a semi metallic state and further to a band insulating state by manipulating the interplay between Zeeman and hybridization interactions. Furthermore, we investigate the effects of chemical potential on the GH shifts. Our results show that the sign of these shifts changes from negative to positive values as the chemical potential is changed from n-type to p-type. The work in this paper sheds important light on controlling GH shifts in different phases of a TI.

Angular control of differential shape-memory alloy spring actuator for underactuated dynamic system

This article dwells on two technical aspects, the design and implementation of an upgraded version of the differential shape-memory alloy–based revolute actuator/rotary actuating mechanism for stabilization and position control of a two-degree-of-freedom centrally hinged ball on beam system. The actuator is configured with differential and inclined placement of shape-memory alloy springs to provide bidirectional angular shift. The shape-memory alloy spring actuator occupies a smaller space and provides more extensive reformation with justifiable actuation force than an equally able shape-memory alloy wire. The cross or diagonal architecture of shape-memory alloy springs provides force amplification and reduces the actuator’s control effort. The shape-memory alloy spring–embodied actuator’s function is exemplified by the highly dynamic underactuated custom-designed ball balancing system. The ball position control is experimentally demonstrated by cascade control using the control laws that have been unattempted for shape-memory alloy actuated systems; the ball is positioned with linear (integer-order and fractional-order) proportional–integral–derivative controllers optimized with genetic algorithm and particle swarm optimization at the outer/primary loop. Angular control of the shape-memory alloy actuated beam is obtained with nonlinear (integer-order and fractional-order sliding mode control) control algorithms in the inner/secondary loop.

Completely Hazy and Transparent Films by Embedding Air Gaps for Elimination of Angular Color Shift in Organic Light-Emitting Diodes.

Red, green, and blue top-emission organic light-emitting diodes (RGB TOLEDs) suffer from white color change with viewing angle due to the microcavity effect, called white angular dependence (WAD). Great efforts are devoted by applying various kinds of hazy films, but they suffer from poor mechanical stability and optical transmittance. Herein, we introduce an air-gap-embedded hazy film (AEHF) to solve these problems and suppress WAD in RGB TOLEDs. The AEHF is designed with optical simulation to realize high haze with transparency. By tuning geometries of the air gap inside the polymer, the AEHF realizes high haze of more than 90% in all RGB colors while maintaining high transparency. To experimentally demonstrate the AEHF, the O2 plasma is treated on a polymer film with AgCl as an etching mask to fabricate microstructures with high aspect ratios. Afterward, PDMS is coated on the patterned surface; air gaps develop spontaneously in the valleys between microstructures during the coating process. Using these processes, an air gap with 1.2 μm size and 400 nm period is formed inside the film and ∼100% haze is achieved while maintaining a high transmittance of 88%; these results agree well with rigorous coupled wave analysis results. By utilizing the AEHF into TOLEDs, the WAD can be drastically suppressed by 95.2% compared with that of a device without AEHF.

123. A novel comprehensive model to describe vertebral body motion following interbody fusion

<h3>BACKGROUND CONTEXT</h3> Subsidence of interbody fusion spinal implants occurs in up to 30% of interbody fusions. Previous methods to quantify subsidence of interbody implants have focused on quantifying changes in disc height or magnitude of erosion of the implant into the vertebral body. These studies focus on the description of subsidence in a cranial-caudal direction. A comprehensive description of subsidence should report cranial-caudal shift, anterior-posterior shift and angular shift of one vertebra with respect to its adjacent vertebra. <h3>PURPOSE</h3> The purpose of the study is to develop and validate a novel method that describes the motion of one vertebral body with respect to its adjacent vertebral body in terms of translation and rotation. We hypothesize this method would have satisfactory interobserver reliability. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of lumbar spine radiographs at a tertiary academic center. <h3>PATIENT SAMPLE</h3> Patients undergoing anterior lumbar interbody fusion at L4-5 or L5-S1 with at least one year radiographic follow-up. <h3>OUTCOME MEASURES</h3> The amount of cranial-caudal shift, anterior-posterior shift and angular shift on preoperative, postoperative, and 1-year postoperative radiographs was recorded according to the novel measurement technique. <h3>Methods</h3> A retrospective review of lateral lumbar spine radiographs was performed by seven physicians (3 residents, 2 fellows, and 2 attendings). The review included radiographic analysis of 10 patients who underwent L4-5 or L5-S1 anterior interbody fusion. Preoperative, postoperative (day 1), and 12-month postoperative radiographs were analyzed. Each vertebra was defined in two-dimensional space by 4 peripheral points at the corners of the vertebral body and a centroid. The upper vertebra was designated as a reference plane by which the motion of the lower vertebra was measured. We measured the movement of the lower vertebra in terms of anterior-posterior translation, cranial caudal translation, and angular change immediately following lumbar interbody fusion and 12 months postoperatively to detect translational and rotational subsidence. Inter-observer reliability was measured using SPSS software. <h3>Results</h3> A model was successfully developed to describe the angular and translational change of one vertebral body with respect to its adjacent segment. The intraclass correlation coefficients of anterior-posterior, cranial-caudal, and angular change were calculated to be 0.75, 0.90, and 0.86, respectively. The average standard deviations of translational and rotational change were 3.3% and 2°, respectively. <h3>Conclusions</h3> A model to comprehensively describe vertebral body motion as a method of characterizing subsidence was successfully developed. The model had good to excellent reliability. Further refinement of the protocol may yield improved intraclass correlation coefficients. This method of measuring vertebral body motion is applicable to measuring modes of failure beyond subsidence such as fracture or delayed fusion. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Wire grid polarizer-based cyclic shearing interferometer with polarization phase shifting

Imaging of transparent phase samples using a wire grid polarizer (WGP)-based shearing interferometer is demonstrated. The proposed setup employs a WGP as a beam splitter in a triangular cyclic interferometer setup, so that the two counterpropagating beams are rendered linearly polarized in orthogonal directions as they emerge from the interferometer. These sheared waved fronts are made to pass through the phase sample. The magnitude of shear is affected by controlled angular shifts of one mirror about the reference X and Y axes. For each of these directional shears, the polarization phase shifting is implemented so as to generate a three-dimensional phase pattern, which is digitally combined and integrated to yield the sample phase. The proposed setup is robust, sufficiently tolerant to ambient vibrations, and shows very encouraging experimental results.

Femtomolar detection of dopamine using surface plasmon resonance sensor based on chitosan/graphene quantum dots thin film

Due to the crucial role of dopamine (DA) in health and peripheral nervous systems, it is particularly important to develop an efficient and accurate sensor to monitor and determine DA concentrations for diagnostic purposes and diseases prevention. Up to now, using surface plasmon resonance (SPR) sensors in DA determination is very limited and its application still at the primary stage. In this work, a simple and ultra-sensitive SPR sensor was constructed for DA detection by preparation of chitosan- graphene quantum dots (CS-GQDs) thin film as the sensing layer. Other SPR measurements were conducted using different sensing layers; GQDs, CS for comparison. The proposed thin films were prepared by spin coating technique. The developed CS-GQDs thin film-based SPR sensor was successfully tested in DA concentration range from 0 fM to 1 pM. The designed SPR sensor showed outstanding performance in detecting DA sensitively (S = 0.011°/fM, R2 = 0.8174) with low detection limit of 1.0 fM has been achieved for the first time. The increased angular shift of SPR dip, narrow full width half maximum of the SPR curves, excellent signal-to-noise ratio and figure of merit, and a binding affinity constant (KA) of 2.962 PM−1 demonstrated the potential of this sensor to detect DA with high accuracy. Overall, it was concluded that the proposed sensor would serve as a valuable tool in clinical diagnostic for the serious neurological disorders. This in turns has a significant socio-economic impact.

Effect of abc Pressing at 573 K on the Microstructure and Martensite Transformation Temperatures in Ti49.8Ni50.2 (at%)

This paper presents experimental data on the microstructure and martensite transformation temperatures of Ti49.8Ni50.2 (at%) after abc pressing (multi-axial forging) to different true strains e from 1.84 to 9.55 at 573 K. The data show that increasing the true strain results in grain–subgrain refinement on different scales at a time. With e = 9.55 at 573 K, the average grain–subgrain size measured approximately 130 nm. Decreasing the abc pressing temperature from 723 to 573 K caused a decrease in all martensite transformation temperatures, a change in the lattice parameters, R phase formation, and angular shifts of diffraction peaks and their broadening. The largest change in the microstructure of Ti49.8Ni50.2 was provided by abc pressing to e = 1.84. Increasing the true strain to e = 9.55 resulted in a much smaller effect, suggesting that the alloy obtained a high density of structural defects even at e = 1.84. Two possible mechanisms of grain–subgrain refinement are discussed.

Molecular Monolayer Sensing Using Surface Plasmon Resonance and Angular Goos-Hänchen Shift.

We demonstrate potential molecular monolayer detection using measurements of surface plasmon resonance (SPR) and angular Goos-Hänchen (GH) shift. Here, the molecular monolayer of interest is a benzenethiol self-assembled monolayer (BT-SAM) adsorbed on a gold (Au) substrate. Excitation of surface plasmons enhanced the GH shift which was dominated by angular GH shift because we focused the incident beam to a small beam waist making spatial GH shift negligible. For measurements in ambient, the presence of BT-SAM on a Au substrate induces hydrophobicity which decreases the likelihood of contamination on the surface allowing for molecular monolayer sensing. This is in contrast to the hydrophilic nature of a clean Au surface that is highly susceptible to contamination. Since our measurements were made in ambient, larger SPR angle than the expected value was measured due to the contamination in the Au substrate. In contrast, the SPR angle was smaller when BT-SAM coated the Au substrate due to the minimization of contaminants brought about by Au surface modification. Detection of the molecular monolayer acounts for the small change in the SPR angle from the expected value.

Photoionization dynamics of Ar trapped in a fullerene anion: Coulomb confinement resonances in 2s subshell and its impact on the 3s subshell

The photoionization dynamics of the inner subshell of an endohedral anion, using relativistic random phase approximation (RRPA), is investigated. The charged nature of the fullerene induces Coulomb confinement resonances (CCRs) not only on the 2s cross-section but also on other dynamical attributes such as angular distribution asymmetric parameter, phase shift, and time delay of the same subshell. More importantly, we find that the 2s CCRs resurrect confinement resonances into the photoionization dynamics of 3s ionization channels at energies far away from the 3s threshold. The impacts of the revivification of these resonances on the 3s cross-section, phase shift, and time delay are explored in this work.

Simultaneous measurement of surface tension and viscosity of oscillating droplet using time-resolved rainbow refractometry

Oscillation of micron-sized liquid droplet is an interesting and common phenomenon, and is used to measure surface tension and viscosity with the recently developed time-resolved rainbow refractometry. Droplets produced by a monodisperse droplet generator are excited to oscillate at a small amplitude (less than 1%) and high frequency (of the order of 10 kHz) by applying a periodic tiny disturbance. The aspect ratio of a spheroidal droplet is quantified by time-resolved angular shift of rainbow signal. Thus the droplet shape oscillation is quantified by its unsphericity, instead of calculated from the polar radius or the variation of surface area. Experiments on several liquids were conducted to evaluate the validation of the experimental system. The results present that the relative errors of measured values of the surface tension and viscosity are less than 5% and 10%, respectively, promising the great potential of rainbow refractometry for liquid surface properties measurement.

Tracking the rotation of a birefringent crystal from speckle correlation

The random intensity distribution observed due to the propagation of a coherent beam of light through a scattering medium is known as a speckle pattern. The interaction of speckles with a birefringent crystal, here, YVO4 results in the splitting of the speckles into e-ray and o-ray speckles. It is observed that the e-ray and o-ray speckles experience an angular shift with the rotation of the crystal and the amount of the shift depends on the rotation angle of the crystal. It is also found that the rate of the shift is different for e-ray and o-ray speckles, and is independent of the topological charge of the beam incident on the scattering medium. The observed rate of shift of the speckles is found to be same as that of the e-ray and o-ray beams. It is experimentally demonstrated that the rotation of a birefringent crystal can be tracked very accurately from the speckle correlation.

Experimental study on the influence of bionic channel structure on waste heat utilization equipment

AbstractIn this paper, in order to improve the efficiency of waste heat utilization, based on the movement type and shape of the snake, snake bionic surfaces with different structures were designed, and CuO–H2O nanofluids were used instead of traditional working fluids, and they were coupled together and applied to waste heat utilization equipment. The main work is to experimentally study the effects of nanofluids mass fraction (w = 0.1 wt%, 0.3 wt%, 0.5 wt%), amplitude of bionic channel structure (A = 1 mm, A = 2 mm, A = 3 mm), angular frequency of bionic channel structure (ω = 20 rad/s, ω = 25 rad/s, ω = 30 rad/s), phase shift of bionic channel structure (α = 0°, 90°, 180°), and Reynolds number (Re = 1,300–1800) on the flow and heat transfer characteristics of working fluid. It was found that the heat transfer capacity of nanofluids increases with nanofluids mass fraction, angular frequency, amplitude and phase shift. Finally, the comprehensive performance of the whole experimental system was studied, and it was found that the greater the angular frequency, amplitude and phase shift, the better the comprehensive performance of the heat exchanger.

Prospects and challenges of mini‐LED, OLED, and micro‐LED displays

AbstractRecently, “liquid crystal display (LCD), organic light‐emitting diode (OLED), or micro‐light‐emitting diode (LED): who wins?” is a heated debatable question. In this review article, we provide a comprehensive overview of these three promising display technologies through nine display performance indicators, including ambient contrast ratio, motion picture response time, viewing angle and angular color shift, color gamut, resolution density, power consumption, cost, lifetime, and thin profile and panel flexibility. The advantages and disadvantages of each technology are analyzed, and their future perspectives are discussed.

Magnetic anisotropy in the van der Waals ferromagnet VI3

A comprehensive study of magnetocrystalline anisotropy of a layered van-der-Waals ferromagnet VI3 was performed. We measured angular dependences of the torque and magnetization with respect to the direction of the applied magnetic field within the "ac" plane perpendicular to and within the basal ab plane, respectively. A two-fold butterfly-like signal was detected by magnetization in the perpendicular "ac" plane. This signal symmetry remains conserved throughout all magnetic regimes as well as through the known structural transition down to the lowest temperatures. The maximum of the magnetization signal and the resulting magnetization easy axis is significantly tilted from the principal c axis by ~40{\deg}. The close relation of the magnetocrystalline anisotropy to the crystal structure was documented. In contrast, a two-fold-like angular signal was detected in the paramagnetic region within the ab plane in the monoclinic phase, which transforms into a six-fold-like signal below the Curie temperature TC. With further cooling, another six-fold-like signal with an angular shift of ~30{\deg} grows approaching TFM. Below TFM, in the triclinic phase, the original six-fold-like signal vanishes, being replaced by a secondary six-fold-like signal with an angular shift of ~30{\deg}.

64‐2: ELQD Performance Modeling

An optimized top emitting (TE) electroluminescent quantum dot (ELQD) LED device design is achieved using Finite Difference Time Domain (FDTD) simulation by allowing the thicknesses for QD Emission layer (EML) and an adjacent hole transmission layer (HTL) layers to differ for R, G, and B subpixels. Optical extraction efficiencies for R, G, and B subpixels reach ∼15, ∼23, and ∼24 % resp., while small angular color shift is sustained. Angular characteristics of the device are very sensitive to the thickness variation of the individual material layers in the design, indicating the importance of thickness control in device fabrication process.

62‐4: Distinguished Student Paper: Doubling the Optical Efficiency of Color‐Converted MicroLED Displays with a Patterned Cholesteric Liquid‐Crystal Polymer Film

We develop a patterned cholesteric liquid crystal polymer film with reflection and scattering states. By integrating this film into a color‐converted micro‐LED display, the optical efficiency is increased by 2.14x at 90% Rec.2020 color gamut and the average angular color shift δu'v′ is reduced from 0.03 to 0.018.

Anomalous Floquet tunneling in uniaxially strained graphene

The interplay of strain engineering and photon-assisted tunneling of electrons in graphene is considered for giving rise to atypical transport phenomena. The combination of uniaxial strain and a time-periodic potential barrier helps to control the particle transmission for a wide range of tunable parameters. With the use of the tight-biding approach, the elasticity theory, and the Floquet scattering, we found an angular shift of the maximum transmission in the sidebands for uniaxial strains breaking the mirror symmetry with respect to the normal incidence, which is called anomalous Floquet tunneling. We show that electron tunneling depends strongly on the barrier width, incident angle, uniaxial strain, and the tuning of the time-periodic potential parameters. An adequate modulation of the barrier width and oscillation amplitude serves to select the transmission in the sidebands. These findings can be useful for controlling the electron current through the photon-assisted tunneling being used in multiple nanotechnological applications.

Theoretical Study of Spatial and Angular Goos-Hänchen Shifts in Quantum System

The behavior of the spatial and angular Goos-Hanchen (GH) shifts for the reflected and transmitted probe light beams is theoretically investigated in a fixed geometrical configuration containing the three and then four – level quantum dot nanostructure. It is found that, by adjusting the controllable parameters such as Rabi frequencies of applied fields, the spatial and angular Goos-Hanchen shifts can be controlled containing both of the positive and negative shifts of reflected and transmitted probe light beams. Moreover, we find that the simultaneous superluminal or subluminal light reflected and transmitted probe beams can be obtained through the medium.

Tunable GH shifts in Weyl thin films on a Weyl substrate

A Weyl semimetal can be considered as a system composed of two Weyl cones breaking time-reversal symmetry, which exhibits strong anisotropic hyperbolic characteristics. The off diagonal components of the permittivity tensor of a Weyl semimetal produce the Faraday and Kerr effects. In this paper, we investigate the Goos–Hänchen (GH) shifts when a light is reflected from the interface of air and a Weyl semimetal. It is demonstrated that the angular GH shift is still tiny; however, the spatial GH shift can be huge and is very sensitive to change in the incident angle. The spatial GH shift can change from positive to negative with an increase in the incident angle. The spatial GH shifts vary at different distances of two Weyl cones and thicknesses of a Weyl semimetal film. Furthermore, the tunable GH shift can be realized by changing the tilting parameter and Fermi energy. These adjustable and giant GH shifts may find practical applications in optical shift devices and optical sensors.