Large Tilt Angle Research Articles

A 3-DOF multi-depth-of-field carrier automatic focusing stage

Abstract Automatic focusing Stage is an important part of automatic focusing system, a 3-DOF (z-axis displacement and XY axis tilt) Multi-Depth-Of-Field Carrier Automatic Focusing Stage (CAFS) is designed, manufactured and tested in this paper. The stage is driven by four piezoelectric (PZT) actuators. Based on four bridge amplifying mechanisms, large displacement travel and tilt Angle are obtained. Compared with other focusing stages, the developed stage adopts the focusing mode of directly adjusting the spatial position of the sample to realize focusing, which not only avoids the inherent defects of objective focusing mode, but also has the advantages of compact structure, low shape and overall manufacturing. In this paper, the structural parameters and the overall design of the stage are determined, and then the characteristics of the focusing stage are finite element analyzed (FEA). Finally, the performance of the focusing stage is studied experimentally. The maximum Z-axis output displacement of the focusing stage is 213.5μm, and the maximum x-direction and Y-direction tilt angles are 1.5 and 1.7mrad, respectively. For the application of CAFS, the practicability of CAFS is verified by Z-axis image superposition acquisition method in automatic focusing system.

Influence of a Background Shear Flow on Cyclone–Anticyclone Asymmetry in Ageostrophic Balanced Flows

In this paper, we study how cyclonic and anticyclonic vortices adapt their shape and orientation to a background shear flow in an effort to understand geophysical vortices. Here we use a balanced model that incorporates the effects of rotation and density stratification to model the case of an isolated vortex of uniform potential vorticity subjected to a background shear flow that mimics the effect of surrounding vortices. We find equilibrium states and analyze their linear stability to determine the vortex characteristics at the margin of stability. Differences are found between the cyclonic and anticyclonic equilibria depending on the background flow parameters. When there is only horizontal strain, the vertical aspect ratio of the vortex does not change, whereas increasing the imposed background strain rate causes a change in the horizontal cross section, with cyclones being more deformed than anticyclones for a given value of strain. Vertical shear not only causes changes in the vertical axis but also causes the vortex to tilt away from it upright position. Overall, anticyclonic equilibria tend to have a more circular horizontal cross section, a longer vertical axis, and a larger tilt angle with respect to cyclonic equilibria. The strongest asymmetry between the horizontal cross section of cyclonic and anticyclonic vortices occurs for low values of vertical shear, while the strongest asymmetry in the vertical axes and tilt angle occurs for large vertical shear. Finally, by expanding the vortex shape and orientation in terms of the strain rate, we derive simple formulas that provide insights into how the vortex equilibria depend on the background flow.

Less is Better than More: Anthropomorphic App Icons With Small versus Large Tilt Angles Were Perceived as More Vivid.

In this study, we explored the impact of tilted designs of anthropomorphic app icons on users' perceptions of icon vividness across three experiments. In Experiment 1, tilting with an angle of 45° to the left increased perceived icon vividness. In Experiment 2, sequential icon tilt angles at 30° intervals manipulation showed that small tilt angles (e.g., 30° to the left or right) enhanced participant perceptions of dynamism and vividness, and participants perceived greater vividness in anthropomorphic app icons with slight tilting, driven by this increased dynamism. In Experiment 3, we excluded the effect of the completeness of icons on these participants' evaluations and affirmed that slightly tilting designs was an effective visual strategy for improving perceived vividness to attract users.

Multiple Satellite Observations of the High‐Latitude Cusp Aurora During Northward IMF Conditions

AbstractCusp auroras poleward of the typical auroral oval are ascribed to high‐latitude lobe reconnection when the Interplanetary Magnetic Field (IMF) Bz is predominantly northward. In this study, we further investigate the ionospheric characteristics of a unique high‐latitude cusp region employing multiple satellite observations. A cusp aurora event with wide spatial spread was observed in the postnoon polar cap region. It was found to be associated with northward IMF Bz and positive By components. The cusp aurora was located from 68° to 86° in magnetic latitude and within 15–17 hr in magnetic local time. This broad coverage in the polar cap indicates direct precipitating particles from the magnetosheath. Particle energy is different between the equatorward and poleward edges of the cusp aurora. The precipitating ions at the equatorward side maintain magnetosheath particle characteristics as expected, while ions with higher energies occurred in the poleward side. Further, the poleward edge of the cusp aurora was nearly situated in the center of a convection shear and was associated with an upward field‐aligned current. These observations suggest a lobe cell circulation, hence we attribute the formation of the cusp aurora to the high‐latitude lobe reconnection. Simultaneous observations in the southern hemisphere indicate the absence of cusp aurora. The auroral presence only in the northern hemisphere is probably due to the combination of large dipole tilt angle and positive IMF Bz, which facilitates the lobe reconnection.

A Reduction in the Rotational Velocity Measurement Deviation of the Vortex Beam Superposition State for Tilted Object

In measuring object rotational velocity using vortex beam, the incident light on a tilted object causes spectral broadening, which significantly interferes with the identification of the true rotational Doppler shift (RDS) peak. We employed a velocity decomposition method to analyze the relationship between the spectral extremum and the central frequency shift caused by the object tilt. Compared with the linear growth trend observed when calculating the object rotational velocity using the frequency peak with the maximum amplitude, the central frequency calculation method effectively reduced the deviation rate of the RDS and velocity measurement value from the true value, even at large tilt angles. This approach increased the maximum tilt angle for a 1% relative error from 0.221 to 0.287 rad, representing a 29.9% improvement. When the tilt angle was 0.7 rad, the velocity measurement deviation reduction rate can reach 5.85%. Our work provides crucial support for achieving high-precision rotational velocity measurement of tilted object.

High-sensitive glucose sensor based on tilted fiber Bragg gratings

In this paper, we proposed a high-sensitive glucose sensor using the tilted fiber Bragg gratings (TFBGs). The TFBGs with different tilt angle has been fabricated by phase mask scanning method with an argon ion double-frequency 244 nm laser. As tilt angle increases, the bandwidth of the cladding mode excited by TFBGs gradually expands and cladding mode region shifts towards shorter wavelengths. The higher-order cladding modes appeared at the shorter wavelength side demonstrate a larger separation in the spectrum. TFBGs with different tilt angles for glucose concentration measurement have been investigated experimentally. When the concentration of glucose solution increases, the surrounding refractive index changing make the cut-off mode resonance shift to a longer wavelength. In addition, the tilt angle of TFBGs does affect the glucose sensitivity, that the larger tilt angle is, the higher sensitivity could achieve. In this work, a maximum glucose sensitivity of 80.91 pm/(mg/ml) could be obtained for TFBGs with tilt angle of 10°. The proposed TFBGs with superiorities of high glucose sensitivity and wider detection range, makes it potential for glucose detection in the field of chemical and biomedical sensing.

Modeling the effects of starspots on stellar magnetic cycles

Context. Observations show that faster rotating stars tend to have stronger magnetic activity and shorter magnetic cycles. The cyclical magnetic activity of the Sun and stars is believed to be driven by the dynamo process. The success of the Babcock-Leighton (BL) dynamo in explaining the solar cycle suggests that starspots could play an important role in stellar magnetic cycles. Aims. We aim to extend the BL mechanism to solar-mass stars with various rotation rates and explore the effects of emergence properties of starspots in latitudes and tilt angles on stellar magnetic cycles. Methods. We adopt a kinematic BL-type dynamo model operating in the bulk of the convection zone. The profiles of the large-scale flow fields are from the mean-field hydrodynamical model for various rotators. The BL source term in the model is constructed based on the rotation dependence of starspot emergence; that is, faster rotators have starspots at higher latitudes with larger tilt angles. Results. Faster rotators have poloidal flux appearing closer to about ±55° latitudes, where the toroidal field generation efficiency is the strongest because of the peak in the strength of the latitudinal differential rotation there. It takes a shorter time for faster rotators to transport the surface poloidal field from their emergence latitude to the ±55° latitudes of efficient Ω-effect, which shortens their magnetic cycles. The faster rotators operate in a more supercritical regime because of a stronger BL α-effect relating to the tilt angles, which leads to stronger saturated magnetic fields and makes the coupling of the poloidal field between two hemispheres more difficult. The magnetic field parity therefore shifts from the hemispherically asymmetric mixed mode to quadrupole, and further to dipole when a star spins down. Conclusions. The emergence of starspots plays an essential role in the large-scale stellar dynamo.

Material parameters ensuring stability of the twist-bend nematic phase

ABSTRACT Properties of the theoretical model of the twist-bend nematic phase (NTB) proposed by Barbero et al. were taken into account. In particular, the role of material parameters that determine the free energy density of the phase was investigated. The regions in parameter space ensuring stability of the NTB were found. Relationships between the parameters, tilt angle and pitch were presented. The ranges of parameters that lead to long (short) pitch and large (small) tilt angle were distinguished. The results allow to obtain useful sets of parameters suitable for studies of stable twist-bend nematic phase.

Energy loss analysis in cavitation flow of a continuous-resistance trim

Energy loss is generated by phase transition and work done on the continuous-resistance trim (CRT) in cavitation flow. This study aims to explore an enhanced CRT design to minimize energy loss in cavitation flow. Four key parameters, specifically orifice shape, inlet velocity, aperture and tilt angle, which have been proven to impact flow in CRT, are examined using a validated numerical method to assess their effects on energy loss in cavitation flow. Furthermore, based on a parametric sensitivity study, an improved design is proposed to control cavitation and reduce energy loss. Findings indicate that changes in orifice shape notably influence the flow area and throttling effect, which are closely connected to energy loss in cavitation. A critical inlet velocity of v1/v0 = 0.5 triggers cavitation occurrence. An orthogonal design method employing L16(45) array is used to analyze the effects of apertures, resulting in the identification of a preferred group with lower energy loss. A larger tilt angle β1/β0 effectively suppresses cavitation generation and significantly decreases energy loss. Finally, an enhanced CRT design is proposed, incorporating a circular (chamfer) orifice shape, an inlet velocity of v1/v0 = 0.3, the preferred aperture group (No.1), and a tilt angle of β1/β0 = 0.66, this improved design showcases reduced energy loss compared to the original CRT design. The findings of this study have broad applications in guiding the implementation of throttling components to suppress cavitation and minimize energy loss.

Green Energy Harvesting and Management Systems in Intelligent Buildings for Cost-Effective Operation

Nowadays, the rise of Internet of Things (IoT) devices is driving technological upgrades and transformations in the construction industry, the integration of IoT devices in buildings is crucial for both the buildings themselves and the intelligent cities. However, large-scale IoT devices increase energy consumption and bring higher operating costs to buildings. Therefore, harvesting the ambient cost-effective and clean energy sources is essential for the future development of intelligent buildings. In this work, we investigate the feasibility of integrating a typical triboelectric droplet energy harvester (DEH) into buildings. We demonstrate the energy harvesting capabilities of DEH on different sloped roof surfaces and complex curved building surfaces by simulating rainy weather with various rainfall intensities. The results indicate energy harvesting efficiency increases with larger tilt angles, which guides future smart architectural designs. This work is significant for the future integration of diversified, all-weather green energy collection and management systems, including raindrop energy, wind power generation, and solar energy, which will contribute to energy conservation and cost control in the next generation of smart buildings.

From ZAMS to merger: Detailed binary evolution models of coalescing neutron star – black hole systems at solar metallicity

Neutron star – black hole (NSBH) merger events bring us new opportunities to constrain theories of stellar and binary evolution and understand the nature of compact objects. In this work, we investigated the formation of merging NSBH binaries at solar metallicity by performing a binary population synthesis study of merging NSBH binaries with the newly developed code POSYDON. The latter incorporates extensive grids of detailed single and binary evolution models, covering the entire evolution of a double compact object progenitor. We explored the evolution of NSBHs originating from different formation channels, which in some cases differ from earlier studies performed with rapid binary population synthesis codes. In this paper, we present the population properties of merging NSBH systems and their progenitors such as component masses, orbital features, and BH spins, and we detail our investigation of the model uncertainties in our treatment of common envelope (CE) evolution and the core-collapse process. We find that at solar metallicity, under the default model assumptions, most of the merging NSBHs have BH masses in the range of 3 − 11 M⊙ and chirp masses within 1.5 − 4 M⊙. Independently of our model variations, the BH always forms first with dimensionless spin parameter ≲0.2, which is correlated to the initial binary orbital period. Some BHs can subsequently spin up moderately (χBH ≲ 0.4) due to mass transfer, which we assume to be Eddington limited. Binaries that experience CE evolution rarely demonstrate large tilt angles. Conversely, approximately 40% of the binaries that undergo only stable mass transfer without CE evolution contain an anti-aligned BH. Finally, accounting for uncertainties in both the population modeling and the NS equation of state, we find that 0 − 18.6% of NSBH mergers may be accompanied by an electromagnetic counterpart.

Simulation of the dynamical transmission of 100 eV positrons through a conical capillary

The simulation of 100 eV positrons transmitted in conical capillary was performed with inserted beam intensity from 0.04 fA/mm2 to 10 fA/mm2. At lower injected intensity of sub-fA, the transmission profile is geometrical and dominated by direct transmission. As the tilt angle increases, the intensity of the transmitted positron decreases rapidly, which is consistent with the experimental data. After increasing injected current intensities to several fA/mm2, charge deposited in the capillary significantly enhances the transmission rate, and the positrons can transmit the capillary with larger tilt angles. The transmitted current density is shown to increase up to a factor of 4.8 with respect to the injected one. These results provide evidence that the low-energy positrons can be guided and significantly focused by insulating conical capillary.

Designing transparent piezoelectric metasurfaces for adaptive optics

Simultaneously generating various motion modes with high strains in piezoelectric devices is highly desired for high-technology fields to achieve multi-functionalities. However, traditional approach for designing multi-degrees-of-freedom systems is to bond together several multilayer piezoelectric stacks, which generally leads to cumbersome and complicated structures. Here, we proposed a transparent piezo metasurface to achieve various types of strains in a wide frequency range. As an example, we designed a ten-unit piezo metasurface, which can produce high strains (ε3 = 0.76%), and generate linear motions along X-, Y- and Z-axis, rotary motions around X-, Y- and Z-axis as well as coupled modes. An adaptive lens based on the proposed piezo metasurface was demonstrated. It can realize a wide range of focal length (35.82 cm ~ ∞) and effective image stabilization with relatively large displacements (5.05 μm along Y-axis) and tilt angles (44.02′ around Y-axis). This research may benefit the miniaturization and integration of multi-degrees-of-freedom systems.

Cerebrovascular responses to a 90° tilt in healthy neonates

BackgroundTilts can induce alterations in cerebral hemodynamics in healthy neonates, but prior studies have only examined systemic parameters or used small tilt angles (<90°). The healthy neonatal population, however, are commonly subjected to large tilt angles (≥90°). We sought to characterize the cerebrovascular response to a 90° tilt in healthy term neonates.MethodsWe performed a secondary descriptive analysis on 44 healthy term neonates. We measured cerebral oxygen saturation (rcSO2), oxygen saturation (SpO2), heart rate (HR), breathing rate (BR), and cerebral fractional tissue oxygen extraction (cFTOE) over three consecutive 90° tilts. These parameters were measured for 2-min while neonates were in a supine (0°) position and 2-min while tilted to a sitting (90°) position. We measured oscillometric mean blood pressure (MBP) at the start of each tilt.ResultsrcSO2 and BR decreased significantly in the sitting position, whereas cFTOE, SpO2, and MBP increased significantly in the sitting position. We detected a significant position-by-time interaction for all physiological parameters.ConclusionA 90° tilt induces a decline in rcSO2 and an increase in cFTOE in healthy term neonates. Understanding the normal cerebrovascular response to a 90° tilt in healthy neonates will help clinicians to recognize abnormal responses in high-risk infant populations.ImpactHealthy term neonates (≤14 days old) had decreased cerebral oxygen saturation (~1.1%) and increased cerebral oxygen extraction (~0.01) following a 90° tilt.We detected a significant position-by-time interaction with all physiological parameters measured, suggesting the effect of position varied across consecutive tilts.No prior study has characterized the cerebral oxygen saturation response to a 90° tilt in healthy term neonates.

Studi Eksperimental: Pengaruh Sudut Kemiringan Dan Massa Terhadap Gerak Linier Kereta Dinamika

Finding out how mass and slope affect the linear motion of dynamic trains is the goal of this investigation. To learn more about how variations in reach and tilt angle can impact an object's acceleration and speed, a variety of tests were conducted in this experiment with varying reach and tilt angle modifications. According to study findings, an object's speed and acceleration are greatly impacted by changes in its size. The object's speed increases in proportion to its mass because larger masses result in faster acceleration. The object's speed is, however, also impacted by variations in the track's inclination angle. An object moves more quickly at a larger tilt angle than it does at a smaller tilt angle. These conclusions are confirmed by calculations that demonstrate how an object's size affects its success. Further developments in this field can be based on the study's results, as they enhance our comprehension of the factors influencing linear motion in dynamic trains.

Simulation of droplet dynamics in an inclined channel considering contact angle hysteresis using the cascade lattice Boltzmann method

Modeling droplet dynamics on solid surfaces with rough or chemically heterogeneous walls is crucial in various industrial applications. In such cases, the downstream and upstream contact lines of the droplet usually move incongruously, leading to droplet deformation known as the contact angle hysteresis (CAH) phenomenon. In this work, we developed a cascaded multicomponent Shan–Chen lattice Boltzmann method to simulate droplet dynamics considering the CAH. Specifically, the Peng–Robinson equation of state is added to one component to improve the density ratio of the model. By modifying the fluid–fluid interaction force scheme, we achieve thermodynamic consistency and independent adjustment of the surface tension. We also implement the modeling of CAH by applying geometric wetting boundaries with a hysteresis window. Based on this model, we first simulated pinned droplets in inclined channels with different hysteresis windows. We obtain the critical tilt angle of the droplet at the onset of sliding, which agrees with the theoretical result. For sliding droplets in the inclined channel, our results reveal that a slight tilt angle is unfavorable for the upstream portion of the droplet sliding, while a large tilt angle is favorable for the entire droplet sliding. A small receding angle results in a large droplet deformation at the quasi-steady state. Finally, by periodically transitioning between different hysteresis windows, enabling exclusive sliding of the upstream contact line during the first half period and subsequent sliding of the downstream contact line during the second half period, we successfully observed the stick-slip phenomenon of the droplet.

Determination of Optimal Geometry for an Empty Concentrator Augmented Wind Turbine

Aims: To determine the optimal concentrator geometrical parameters of an empty concentrator augmented wind turbine (CAWT), which are used to design and install CAWTs. Place and Duration of Study: Physics Department, University of Fort Hare, South Africa between March 2023, and October 2023. Methodology: The study used the concentrator length (L) to concentrator outlet diameter ratio (Lr) and the difference between inlet and outlet radii to concentrator outlet diameter ratio (Rr) to investigate the effect of concentrator geometry on wind velocity augmentation and air dynamics to determine the optimum concentrator geometrical parameters using computational fluid dynamics modelling. The modelled concentrators’ geometry was created in SolidWorks, prepared for meshing in SpaceClaim, meshed, and analysed in Fluent to solve the Reynolds-averaged Navier-Stokes equations, and validated by primary experimental results. To make the concentrators, six equally spaced Lr were used in the range 0.1 \(\le\) Lr \(\le\) 0.6 and thirteen equally spaced Rr in the range 0.025 \(\le\) Rr \(\le\) 0.325 . The concentrators’ performance was investigated in terms of velocity augmentation ratio (Vr) and concentrator efficiency (\(\eta\)c). Results: It was observed that the variation in Vr was influenced by the change in both Lr and Rr. The Vr and \(\eta\)c increased with an increase in Lr to a maximum at optimum Lr and decreased thereafter. The optimum Vr was obtained at Lr = 0.4 and Rr = 0.1 with a maximum velocity at the concentrator outlet. It was also shown that the energy losses due to friction negatively impact velocity augmentation more than energy losses due to a large concentrator tilt angle at high Lr . Conclusion: When constructing a CAWT, the turbine rotor should be placed at any distance between the concentrator outlet and 0.5L behind the concentrator, and the blade tips of the turbine in a CAWT system should be at least 10% smaller than the concentrator outlet radius, for the whole rotor to receive wind with augmented velocity.

Artificial neural network for tilt compensation in yaw estimation

Low-cost inertial measurement units (IMUs) are commonly used to determine the orientation of objects, such as unmanned aerial vehicles (UAVs) and smartphones. They calculate yaw by measuring Earth’s magnetic field’s horizontal components. However, in the presence of tilt (pitch or roll), a tilt-compensation operation is necessary. This is usually done by projecting measurements onto a horizontal plane. This method has limitations, particularly for large tilt angles and when the IMU is pointing toward the east or west directions. In this paper, we expose the shortcomings of this conventional approach and propose a novel machine learning–based solution employing an artificial neural network (ANN). This method eliminates the need to determine tilt angles and uses accelerometer and magnetometer measurements as its inputs. The dataset for training and testing the ANN was collected based on a 3D nonmagnetic scaled platform, using a low-cost IMU and a Raspberry Pi platform. On one hand, our method outperforms the conventional tilt-compensation technique and other complementary filters (Madgwick and Mahony) in terms of accuracy, as evidenced by the root mean square error (RMSE = 1.95°). However, this superiority comes at the expense of a more complex system that consumes more processing time.

Stratified inclined duct: two-layer hydraulics and instabilities

The stratified inclined duct (SID) sustains an exchange flow in a long, gently sloping duct as a model for continuously forced density-stratified flows such as those found in estuaries. Experiments have shown that the emergence of interfacial waves and their transition to turbulence as the tilt angle is increased appears to be linked to a threshold in the exchange flow rate given by inviscid two-layer hydraulics. We uncover these hydraulic mechanisms by (i) using recent direct numerical simulations (DNS) providing full flow data in the key flow regimes (Zhu et al., J. Fluid Mech., vol. 969, 2023, A20), (ii) averaging these DNS into two layers, and (iii) using an inviscid two-layer shallow-water and instability theory to diagnose interfacial wave behaviour and provide physical insight. The laminar flow is subcritical and stable throughout the duct and hydraulically controlled at the ends of the duct. As the tilt is increased, the flow becomes supercritical everywhere and unstable to long waves. An internal jump featuring stationary waves first appears near the centre of the duct, then leads to larger-amplitude travelling waves, and to stronger jumps, wave breaking and intermittent turbulence at the largest tilt angle. Long waves described by the (nonlinear) shallow-water equation are interpreted locally as linear waves on a two-layer parallel base flow described by the Taylor–Goldstein equation. This link helps us to interpret long-wave instability and contrast it with short-wave (e.g. Kelvin–Helmholtz) instability. Our results suggest a transition to turbulence in SID through long-wave instability relying on vertical confinement by the top and bottom walls.

Maximum Acceptable Tilt Angle for Point Autofocus Microscopy.

The complete and accurate acquisition of geometric information forms the bedrock of maintaining high-end instrument performance and monitoring product quality. It is also a prerequisite for achieving the 'precision' and 'intelligence' that the manufacturing industry aspires to achieve. Industrial microscopes, known for their high accuracy and resolution, have become invaluable tools in the precision measurement of small components. However, these industrial microscopes often struggle to demonstrate their advantages when dealing with complex shapes or large tilt angles. This paper introduces a ray-tracing model for point autofocus microscopy, and it provides the quantified relationship formula between the maximum acceptable tilt angle and the beam offset accepted in point autofocus microscopy, then analyzing the maximum acceptable tilt angle of the objects being measured. This novel approach uses the geometric features of a high-precision reference sphere to simulate the tilt angle and displacement of the surface under investigation. The research findings show that the maximum acceptable tilt angles of a point autofocus microscope vary across different measured directions. Additionally, the extent to which the maximum acceptable tilt angles are affected by the distances of the beam offset also varies. Finally, the difference between the experiment results and the theoretical results is less than 0.5°.