Spatial Angle Research Articles

Adaptive beam forming across temperature variation in optical phased array enabled with deep neural network

Integrated optical phased arrays (OPA) require calibration to account for mismatches amongst the channels. Furthermore, beams emitted from an OPA tend to distort when the chip’s temperature changes. We propose to utilize a deep neural network (DNN) to adaptively control the phase modulator voltages of the OPA and create a desired beam pattern in the presence of process mismatches and temperature changes. As a proof of concept, adaptive beam forming was demonstrated with an integrated 128-channel OPA realized in a commercial foundry silicon photonics (SiP) process. Beam forming within 50° field of view (FoV) is demonstrated, while accuracy of 0.025° is achieved when the beam is swept in 0.1° step at a fixed temperature. The DNN is also used to create beams with multiple peaks at desired spatial angles. The DNN is shown to properly adjust the phase modulator voltages to keep the beam nearly intact as temperature changes within 20°C range.

In-situ rapid nondestructive characterization of multiple irregular three-dimensional grain boundary structures and electrical properties by nanorobot with SEM in ZnO

To address the problem of spatial quantification of irregular grain boundaries, a unique approach for the nondestructive characterization of multiple irregular three-dimensional grain boundaries is proposed using nanorobots with scanning electron microscopy (SEM) to accomplish in-situ rapid synchronized quantification of structures and electrical properties. By constructing a three-dimensional trigonometric geometric mapping relationship, multiple irregular three-dimensional grain boundary structures and electrical properties can be rapidly quantified. Experimental results demonstrate that it is feasible to accomplish in-situ rapid nondestructive characterizations. The two-dimensional profile shapes of the targeted grain boundaries at each layer exhibit irregular and non-uniform features in the Y-Z plane. The hypotenuse length between the virtual space tilting lines presents a three-dimensional characteristic in the X-Z plane. The spatial tilt angle of the virtual space tilting line can be calculated using the right-triangle relation. The unequal numbers of grains along the same tilted hypotenuse direction with equal lengths directly illustrate the existence of irregular and nonlinear grain boundaries in bulk ZnO ceramics. The relatively uniform spatial sizes of the grain boundary illustrate the coupled spatial characteristics existing in the irregular micro-structures. The relatively uniform equivalent circuit fitting parameters confirm the existence of relatively uniform doping components in bulk ZnO ceramics. Furthermore, this method provides a unique approach for the rapid nondestructive quantitative analysis of multiple three-dimensional irregular grain boundaries in bulk polycrystalline materials.

Detection of left ventricular systolic dysfunction in patients with ischemic heart disease using spatial and frontal QRS-T angles of the electrocardiogram

Aim. To evaluate the possibilities of the spatial QRS-T angle (sQRS-Ta) and the frontal QRS-T angle (fQRS-Ta) to detect low left ventricular ejection fraction (LVEF) in patients with chronic coronary heart disease. Materials and methods. We analyzed the data of 287 patients with chronic coronary artery disease, in 80 cases complicated by chronic heart failure with low LVEF. fQRS-Ta was calculated as absolute value of the difference between the frontal plane QRS and T axes. sQRS-Ta was calculated using the synthesized vectorcardiogram as a spatial angle between the integral QRS and T vectors. Results. The fQRS-Ta values in the group were 70 [25; 141]°. sQRS-Ta values in the group were 96 [55; 148]°. There were correlations between fQRS-Ta and LVEF (r=-0.58; p0.0001) and sQRS-Ta with LVEF (r=-0.63; p0.0001). According to the ROC analysis, fQRS-Ta with a threshold value of 90° made it possible to identify patients with LVEF≤40% with a sensitivity of 85% and a specificity of 75% (area under the ROC curve 0.85±0.03) and patients with LVEF≤35% with 87% sensitivity and 69% specificity (area under the ROC curve 0.84±0.04). sQRS-Ta with a threshold value of 125° made it possible to identify patients with LVEF≤40% with a sensitivity of 86% and a specificity of 82% (area under the ROC curve 0.89±0.03) and patients with LVEF≤35% with sensitivity 93% and specificity 76% (area under the ROC curve 0.89±0.02). Conclusion. In patients with chronic coronary artery disease, as the LVEF decreases, the frontal and spatial angles between the QRS and T vectors increase. These indicators with sufficiently high sensitivity and specificity make it possible to identify patients with reduced LVEF among patients with chronic coronary artery disease.

Human in vivo midtarsal and subtalar joint kinematics during walking, running and hopping.

The interaction among joints of the midtarsal complex and subtalar joint is important for locomotor function; however, its complexity poses substantial challenges in quantifying the joints' motions. We determine the mobility of these joints across locomotion tasks and investigate the influence of individual talus morphology on their motion. Using highly accurate biplanar videoradiography, three-dimensional bone kinematics were captured during walking, running and hopping. We calculated the axis of rotation of the midtarsal complex and subtalar joint for the landing and push-off phases. A comparison was made between these rotation axes and the morphological subtalar axis. Measurement included total rotation about and the orientation of the rotation axes in the direction of the subtalar joint and its deviation via spatial angles for both phases. The rotation axes of all three bones relative to the talus closely align with the morphological subtalar axis. This suggests that the midtarsal and subtalar joints' motions might be described by one commonly oriented axis. Despite having such an axis, the location of the axes and ranges of motion differed among the bones. Our results provide a novel perspective of healthy foot function across different sagittal plane-dominant locomotion tasks underscoring the importance of quantifying midtarsal complex and subtalar motion while accounting for an individual's talus morphology.

Effect of spatial setting angle on vibration of elastically restrained rotating beams

For a fully articulated rotor system, there may exist a spatial setting angle and elastically restrained root for each individual blade in rotation procedure due to flapping, drag and pitch hinges. Most of previous studies on rotating blades or beams focused on pitch angle and clamped root. In this paper, a three-dimensional dynamic model is proposed for elastically restrained rotating beams with spatial setting angle. The elastic deformation of the beam is expressed by three scalar variables in three-dimensional space including stretch deformation instead of the conventional axial deformation. The longitudinal shrinkage is considered to capture centrifugal forces. The penalty method is adopted to deal with the elastic constraints, which greatly simplifies the construction of admissible functions. A unified formulation is derived by a variational principle combined with Chebyshev orthogonal polynomials. One of the advantages of the present method is that any linearly independent and complete basis functions can be used as admissible function regardless of boundary conditions, and another advantage is that the present method is capable of handling arbitrary boundary conditions by only adjusting the values of penalty factor. The convergence and accuracy of the present method are validated by comparison, and the effects of boundary conditions, angular velocity and spatial setting angle on vibration characteristics are discussed in detail. The results show that natural frequencies increase as the spring stiffness rises in a certain range and the spatial setting angle plays a more significant role on dynamic characteristics for rotating beams.

Application of Posture Recognition Model Based on Improved CORDIC Algorithm in Spatial Health Monitoring of the Elderly Living Alone

In an aging society, accidental falls are highly likely to occur due to external factors or the incidence of diseases in the elderly. Serious consequences can arise when an elderly person living alone falls and is unable to get up to call for help. To address the issue of automatic assistance for elderly individuals living alone when they fall by accident, and the problem of behavioral analysis in daily life, this paper designs and develops an elderly monitoring system through the study of feature extraction algorithms and posture recognition algorithms. Furthermore, this paper has also developed a set of three-dimensional spatial angle calculation methods suitable for implementation on a microcontroller. The CORDIC algorithm can compute two-dimensional spatial angles through simple addition, subtraction, and bit shifting operations. Through careful study of the CORDIC algorithm, it was found that applying the CORDIC algorithm twice can achieve the calculation of three-dimensional spatial angles. Through experimental testing, we can see that the algorithms proposed in this paper have achieved good experimental results in terms of computational accuracy and operation time, reaching a relatively advanced level.

Measurements of Spatial Angles Using Diamond Nitrogen-Vacancy Center Optical Detection Magnetic Resonance.

This article introduces a spatial angle measuring device based on ensemble diamond nitrogen-vacancy (NV) center optical detection magnetic resonance (ODMR). This device realizes solid-state all-optical wide-field vector magnetic field measurements for solving the angles of magnetic components in space. The system uses diamond NV center magnetic microscope imaging to obtain magnetic vector distribution and calculates the spatial angles of magnetic components based on the magnetic vector distribution. Utilizing magnetism for angle measuring enables non-contact measuring, reduces the impact on the object being measured, and ensures measurement precision and accuracy. Finally, the accuracy of the system is verified by comparing the measurement results with the set values of the angle displacement platform. The results show that the measurement error of the yaw angle of the system is 1°, and the pitch angle and roll angle are 1.5°. The experimental results are in good agreement with the expected results.

An attentional approach to geometrical illusions.

It is known for a long time that some drawings composed of points, lines, and areas are systematically misperceived. The origin of these geometrical illusions is still unknown. Here we outline how a recent progress in attentional research contributes to a better understanding of such perceptual distortions. The basic idea behind this approach is that crucial elements of a drawing are differently attended. These changes in the allocation of spatial attention go along with systematic changes in low-level spatial coding. As a result, changes in the perception of spatial extent, angles, positions, and shapes can arise. How this approach can be applied to individual illusions is discussed.

Probabilistic analysis of dual circular tunnels in rock masses considering rotated anisotropic random fields

Considering the spatial variability of rock masses in tunnelling analysis is a challenge in geotechnical engineering. This paper focuses on predicting collapse loads and probabilities of design failure for dual circular tunnels constructed in anisotropic rock masses. This study employs the random adaptive finite element limit analysis method, which incorporates rotated anisotropic random fields, to model uncertainties in rock mass properties. The generalised Hoek–Brown constitutive model is employed to define the yield failure criteria of a rock mass. The adaptive finite element limit analysis is first validated against a previous study, demonstrating good agreement. Then, the probability of design failure for dual circular tunnels is comprehensively investigated. This study emphasises the importance of considering both geometric parameters and rotated anisotropic random fields in comprehensive probabilistic analyses. The results provide insights into the mean and coefficient of variation of the stability numbers, as well as the probability of design failure for different geometric configurations and rotated anisotropic random fields. In conclusion, the variation in failure probability for practical applications is presented, highlighting the significance of accounting for spatial variability, rotation angle and anisotropy in rock mass properties in tunnelling.

Semi-analytic modeling and experimental verification of arbitrary aero-engine complex spatial pipeline

In-depth research is imperative for complex spatial pipelines with fluid-structure interaction. A comprehensive and universal three-dimensional semi-analytical modeling method is first established for complex fluid-conveying spatial pipelines under the base excitation with arbitrary connections and configurations under different boundary conditions. The virtual spring technology is used to connect the straight and curved pipeline segments with spatial angles and simulate boundary conditions. For a thorough analysis, the actual stiffness of the bracket-clamp system is experimentally measured for the first time. The multi-level coupling dynamic model of part, component, and system levels under actual boundary conditions is established. An efficient method for solving the fluid-structure coupling pipeline system dynamics considering the base excitation is proposed based on energy method. The mid-plane displacement function of the Fourier series is introduced and solved using the principle of modal superposition. Hammer impact modal experiments, ANSYS software and vibration response experiments are performed on spatial pipelines supported by flexible bracket-clamps; the numerical and experimental results support the semi-analytical results. The degenerate model is verified with the simple plane pipelines in other references, and the errors are less than 5 %. The proposed method exhibits broad applicability and generalizability, making it suitable for various configurations and boundary conditions.

Method of inclined hole axis adjustment based on geometric optimization and minimum zone theory

The machining accuracy of the axis position and spatial angle of the array microholes with high aspect ratio on the components of the high-end equipment manufacturing industry will directly affect the performance of the whole machine. A method of tilt hole axis adjustment is proposed in this paper. It utilizes geometric optimization and minimum zone theory to measure the position and spatial angle of the hole axis. This addresses the slight angle error that occurs after correcting the inclined hole axis using visual techniques. Based on the minimum zone criterion for the cylindricity error, the evaluation model is re-established through the inner and the outer loop and spatial projection, which includes roundness evaluation of the projection curve by an improved particle swarm optimization (PSO) algorithm and elliptic fitting by a geometric parameter method, so as to obtain the optimal solution of the axis vector and spatial angle. Experimental comparison with the theory above shows that the precision of the method proposed is better than that of the least squares method and the traditional PSO algorithm based on the minimum zone criterion. The research results indicate that the precision of the tilt angle is better than 0.03°, and simultaneously the rotation angle is better than 0.1° in the range of 1°. This experiment verifies the effectiveness and accuracy of the proposed method.

Cross-Layer and Cross-Sample Feature Optimization Network for Few-Shot Fine-Grained Image Classification

Recently, a number of Few-Shot Fine-Grained Image Classification (FS-FGIC) methods have been proposed, but they primarily focus on better fine-grained feature extraction while overlooking two important issues. The first one is how to extract discriminative features for Fine-Grained Image Classification tasks while reducing trivial and non-generalizable sample level noise introduced in this procedure, to overcome the over-fitting problem under the setting of Few-Shot Learning. The second one is how to achieve satisfying feature matching between limited support and query samples with variable spatial positions and angles. To address these issues, we propose a novel Cross-layer and Cross-sample feature optimization Network for FS-FGIC, C2-Net for short. The proposed method consists of two main modules: Cross-Layer Feature Refinement (CLFR) module and Cross-Sample Feature Adjustment (CSFA) module. The CLFR module further refines the extracted features while integrating outputs from multiple layers to suppress sample-level feature noise interference. Additionally, the CSFA module addresses the feature mismatch between query and support samples through both channel activation and position matching operations. Extensive experiments have been conducted on five fine-grained benchmark datasets, and the results show that the C2-Net outperforms other state-of-the-art methods by a significant margin in most cases. Our code is available at: https://github.com/zenith0923/C2-Net.

A real space Moiré inversion technique and its practical applications in real space for lattice reconstruction

Distinct physical properties emerge at the nanoscale in Moiré materials, such as bilayer graphene and layered material superposition. This study explores similar structural features within a second-generation nickel-based superalloy, unveiling potential formation mechanisms. Introducing the real space Moiré inversion method (RSMIM) for nanoscale imaging, combined with the transmission electron microscopy (TEM) nano-Moiré inversion method, we reveal spatial angles between specimen and reference lattices in 3D. Simultaneously, we reconstruct the Moiré pattern region to deepen us understand the phenomenon of Moiré formation. Focused on face-centered cubic structures, the research identifies six spatial angles, shedding light on Moiré patterns in the superalloy. The RSMIM not only enhances understanding but also expands 3D structure measurement capabilities. The RSMIM served to validate TEM nano-Moiré inversion results, ascertaining the spatial relative angle between lattices, and establishing a theoretical simulation model for Moiré patterns. This study marks a substantial step toward designing high-performance nanomaterials by uncovering dynamic Moiré variations.

Relation between spatial release from informational masking and localization discrimination

Spatial release from masking (SRM) occurs when a signal of interest (target) and an interfering sound (masker) come from different locations in space. SRM and sound localization are assumed to share common mechanisms, but it is still unclear whether SRM actually depends on hearing the target and masker in different places, even in situations dominated by informational masking. The current study used a spatial rhythmic release from masking (RMR) task [J. Middlebrooks and Z. Onsan, JASA, 132, 3896–3911, 2012]. The target and masker were trains of non-simultaneous noise bursts; hearing the target temporal pattern relies on segregation from the masker, which is supported by spatial separation. Using a headphone simulation of space (HRTFs), the current study replicated key aspects of Middlebrooks and Onsan’s (2012) finding that RMR spatial thresholds were poorer for high-frequency than low-frequency bursts. We investigated whether this low/high frequency difference, and others created with degraded localization cues, were associated with variations in basic localization discrimination tasks using the same RMR stimuli. Data collection is ongoing, but preliminary results suggest a covariation of spatial release in the RMR task and sensitivity to change in spatial angle. [Work supported by NIDCD R01-01625.]

Effect of Carboxyl Group Position on Assembly Behavior and Structure of Hydrocarbon Oil-Carboxylic Acid Compound Collector on Low-Rank Coal Surface: Sum-Frequency Vibration Spectroscopy and Coarse-Grained Molecular Dynamics Simulation Study.

In this work, the assembly behavior and structure of a compound collector with different carboxyl group positions at the low-rank coal (LRC)-water interface were investigated through coarse-grained molecular dynamics simulation (CGMD) combined with sum-frequency vibration spectroscopy (SFG). The choice of compound collector was dodecane +decanoic acid (D-DA) and dodecane +2-butyl octanoic acid (D-BA). CGMD results showed that the carboxyl group at the carbon chain's middle can better control the assembly process between carboxylic acid and D molecules. SFG research found that the carboxyl group at the carbon chain's termination had a greater impact on the displacement of the methyl/methylene symmetric stretching vibration peak, while the carboxyl group at the carbon chain's middle had a greater impact on the displacement of the methyl/methylene asymmetric stretching vibration peak. The spatial angle calculation results revealed that the methyl group's orientation angle in the D-BA molecule was smaller and the carboxyl group's orientation angle in the BA molecule was bigger, indicating that D-BA spread more flatly on the LRC surface than D-DA. This meant that the assembled structure had a larger effective adsorption area on the LRC surface. The flotation studies also verified that the assembly behavior and structure of D-BA with the carboxyl group at the carbon chain's middle at the LRC-water interface were more conducive to the improvement of flotation efficiency. The study of interface assembly behavior and structure by CGMD combined with SFG is crucial for the creation of effective compound collectors.

Optimized Design of Pipe Elbows for Erosion Wear

Multiphase flows are widely used to transport solid–liquid mixtures in oil and gas fields. The pipeline structures used can suffer damage from the high-pressure sand-carrying fracturing fluid, causing erosion and wear failures in the engineering field. In this work, an erosion model that considers particle turbulent kinetic energy and the effect of the design’s structural parameters on the erosion wear of spatial pipe structures is established using computational fluid dynamics (CFD). Structural parameters such as the bending diameter ratio, bending angle and spatial angle are discussed, and the location and degree of each parameter with regard to the erosion rate are obtained. The results show that the included angle of the pipe elbow has the greatest influence on erosion wear among the structural parameters. Several typical anti-erosion optimization models are compared and analysed, and a corrugated anti-erosion structure based on a bionic structure is further proposed. It is found that the anti-erosion performance of the T-type blind long header pipe is better in terms of the numerical value of the erosion rate, while for the erosion cloud diagram, the anti-erosion performance of the corrugated structure is superior. Finally, some suggestions for the application of the anti-erosion structure in the engineering field are given, and technical support is provided for the anti-erosion structure design and practical application of space pipeline systems in the future.

Intensity controlled and multi-multiplexed full-space achromatic metalens and modulated orbital angular momentum.

The Fabry-Perot (F-P) interference model was used to make a 6-layer metasurface with cross-polarization that can be changed by heat. The fundamental concept behind the metasurface is to utilize the selectivity of linearly polarized waves by a metal grating to achieve broadband and efficient polarized conversion (PC). It also uses the thermal conversion properties of vanadium dioxide (VO2) to control the amplitude of terahertz (THz) waves in a dynamic way. While achromatic metalenses have been extensively studied, altering the entire spatial incidence angle remains relatively uncommon. Enter modulated orbital angular momentum (MOAM), a promising approach for applications such as holographic encryption, optical communication, and imaging. However, achieving MOAM multidimensional multiplexing has proven to be a significant challenge. In response to this challenge, we have integrated the transmission phase into the metasurface design. This new idea makes it possible to make a full spatially achromatic metalenses with angular multiplexing and makes MOAM multidimensional multiplexing easier by letting you switch between frequency, angle, and MOAM modes. This pioneering approach unveils new prospects for enhancing the capacity, rate, and quality of information exchange in domains such as optical encryption, optical imaging, optical communication, and other related technological fields.

Alleviation Effects of Hoods at the Entrances and Exits of High-Speed Railway Tunnels on the Micro-Pressure Wave

The MPW that emits from a tunnel’s exit when a high-speed train passes through is a serious environmental problem which increases rapidly with the speed of the train. To alleviate the MPW problem at 400 km/h, the aerodynamic effects caused by the hood located at the entrance or exit of a tunnel are studied by numerical method, and the influences of hood geometry, such as an enlarged cross-section, oblique entrance, and opening holes on the MPW, are also investigated. The research indicates that the enlarged cross-section of the hood at the entrance and exit of the tunnel has opposite effects on the MPW, and the oblique section can alleviate the MPW by extending the rising time of the compression wave and increasing the spatial angle at the hood exit. The pressure gradient can be mitigated through delaying the rising of the compression wave by opening holes on the side wall of the hood, and the relief effects of the holes can reduce the MPW further. The MPW problem when a train passes through a tunnel at 400 km/h can be effectively alleviated by an optimized oblique enlarged hood with opening holes, even up to train speeds of 500 km/h.

Morphological effects of WO3 in metal sulfide-based S-Scheme heterojunctions for boosting photocatalytic hydrogen production

In the field of photocatalytic hydrogen production, metal sulfides are frequently utilized, particularly Cd sulfides, which have the benefits of a narrow band gap and a sufficient band gap. Other photocatalysts are required to enhance the situation because it still has a high photogenic carrier recombination rate and has flaws like photocorrosion that need to be fixed. The best morphology combination must be chosen since, as we are all aware, the morphology of the catalyst can significantly alter its activity. To choose the best morphology, we chose maple leaf CdS and WO3 with various morphologies to construct the S-Scheme heterojunctions, and WO3 was then applied to other metal sulfides. It is concluded that granular WO3–0D and CdS-F have the highest hydrogen evolution activity, which may indicate that 0D has the highest loading capacity and may play a certain supporting role for the catalyst that is easy to agglomerate, exposing more hydrogen evolution active sites to enhance hydrogen production. At the same time, the main hydrogen evolution active crystal face of the metal sulfide in the paper is (1 0 0) crystal face. When the crystal face is exposed, the metal sulfide in the paper has good hydrogen evolution activity, and the hydrogen evolution activity will be greatly reduced after the crystal face is covered. The established spatial angle between the (1 0 0) crystal face exposed by CdS-F and the (1 1 1) crystal face exposed by WO3–0D is large, so the highly active crystal face and active site are preserved as much as possible. On the other hand, WO3 decreases the recombination rate of electron-hole pairs in metal sulfide, resulting in a greater contribution of photogenerated electrons to the hydrogen evolution reaction. The Tafel clearly demonstrates the variation of hydrogen production rate control steps. This offers some suggestions for choosing the photocatalyst's morphological configuration.

Simple photocleavable indoline-based materials for surface wettability patterning

Surface wettability is controlled through UV light-induced photocleavage of indoline-based small molecules. Simple, solution-based deposition enables photopatterning with excellent spatial control and contact angle changes up to 61°.