Orthogonal Angles Research Articles

Self-traceable angle standards with simplified traceability chain for dimensional metrology

Traceability is a fundamental issue for ensuring accuracy of nanometrology. A shortened traceability chain is advantageous for reducing calibration steps, thus reducing errors and raising application efficiency. A novel kind of two-dimensional grating is manufactured by atom lithography, whose pitch and (orthogonal) angle values are directly determined by natural constants, offering a feasible approach for effectively shortening the traceability chain. The PTB’s calibration results show that the two-dimensional grating has excellent orthogonality with a deviation of only 0.001°. The application of two-dimensional grating is demonstrated for the characterization of the angular distortion of a SEM, showing its great application potential.

Four-dimensional laser absorption cinematography of species and temperature dynamics at 2 kHz in reacting flows.

A four-dimensional (4D) mid-infrared laser absorption imaging technique has been developed and demonstrated for quantitative, time-resolved, volumetric measurements of temperature and species concentration in dynamic combustion flows. This technique employs a dual high-speed infrared camera setup to capture turnable radiation from a quantum cascade laser near 4.85 µm to resolve rovibrational absorption transitions of carbon monoxide at two orthogonal projection angles. The laser is modulated with a customized waveform to adaptively resolve two target transitions with an increased density of data samples in proximity to the transition peaks, therefore ensuring accurate and quantitative spectral interpretation while minimizing the required frame rate. A 3D masked Tikhonov regularized inversion was performed to reconstruct spectrally resolved absorbance at every grid point of each frame, which enables subsequent interpretation of local gas properties in time. These methods are applied to achieve quantitative 4D cinematography of temperature and carbon monoxide in a propagating C2H4/O2 flame with a spatial pixel resolution of ∼70 µm and a temporal resolution of 2 kHz.

Density-constrained Chemotaxis and Hele-Shaw flow

We consider a model of congestion dynamics with chemotaxis, where the density of cells follows the chemical signal it generates, while observing an incompressibility constraint (incompressible parabolic-elliptic Patlak-Keller-Segel model). We show that when the chemical diffuses slowly and attracts the cells strongly, then the dynamics of the congested cells is well approximated by a surface-tension driven free boundary problem. More precisely, we rigorously establish the convergence of the solution to the characteristic function of a set whose evolution is determined by the classical Hele-Shaw free boundary problem with surface tension.The problem is set in a bounded domain, which leads to an interesting analysis on the limiting boundary conditions. Namely, we prove that the assumption of Robin boundary conditions for the chemical potential leads to a contact angle condition for the free interface (in particular Neumann boundary conditions lead to an orthogonal contact angle condition, while Dirichlet boundary conditions lead to a tangential contact angle condition).

A New Emission Mode of PSR B1859+07

Previous studies have identified two emission modes in PSR B1859+07: a normal mode that has three prominent components in the average profile, with the trailing one being the brightest, and an anomalous mode (i.e., the A mode) where emissions seem to be shifted to an earlier phase. Within the normal mode, further analysis has revealed the presence of two submodes, i.e., the cW mode and cB mode, where the central component can appear either weak or bright. As for the anomalous mode, a new bright component emerges in the advanced phase while the bright trailing component in the normal mode disappears. New observations of PSR B1859+07 using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) have revealed the existence of a previously unknown emission mode, dubbed the Af mode. In this mode, all emission components seen in the normal and anomalous modes are detected. Notably, the mean polarization profiles of both the A and Af modes exhibit a jump in the orthogonal polarization angle modes in the bright leading component. The polarization angles for the central component in the original normal mode follow two distinct orthogonal polarization modes in the A and Af modes respectively. The polarization angles for the trailing component show almost the same but a small systematic shift in the A and Af modes, roughly following the values for the cW and cB modes. Those polarization features of this newly detected emission mode imply that the anomalous mode A of PSR B1859+07 is not a result of “phase shift” or “swooshes” of normal components, but simply a result of the varying intensities of different profile components. Additionally, subpulse drifting has been detected in the leading component of the Af mode.

Can Wearable Sensors Provide Accurate and Reliable 3D Tibiofemoral Angle Estimates during Dynamic Actions?

The ability to accurately measure tibiofemoral angles during various dynamic activities is of clinical interest. The purpose of this study was to determine if inertial measurement units (IMUs) can provide accurate and reliable angle estimates during dynamic actions. A tuned quaternion conversion (TQC) method tuned to dynamics actions was used to calculate Euler angles based on IMU data, and these calculated angles were compared to a motion capture system (our "gold" standard) and a commercially available sensor fusion algorithm. Nine healthy athletes were instrumented with APDM Opal IMUs and asked to perform nine dynamic actions; five participants were used in training the parameters of the TQC method, with the remaining four being used to test validity. Accuracy was based on the root mean square error (RMSE) and reliability was based on the Bland-Altman limits of agreement (LoA). Improvement across all three orthogonal angles was observed as the TQC method was able to more accurately (lower RMSE) and more reliably (smaller LoA) estimate an angle than the commercially available algorithm. No significant difference was observed between the TQC method and the motion capture system in any of the three angles (p < 0.05). It may be feasible to use this method to track tibiofemoral angles with higher accuracy and reliability than the commercially available sensor fusion algorithm.

Full-Volume 3D Fluid Flow Reconstruction With Light Field PIV.

Particle Imaging Velocimetry (PIV) is a classical method that estimates fluid flow by analyzing the motion of injected particles. To reconstruct and track the swirling particles is a difficult computer vision problem, as the particles are dense in the fluid volume and have similar appearances. Further, tracking a large number of particles is particularly challenging due to heavy occlusion. Here we present a low-cost PIV solution that uses compact lenslet-based light field cameras as imaging device. We develop novel optimization algorithms for dense particle 3D reconstruction and tracking. As a single light field camera has limited capacity in resolving depth (z-dimension measurement), the resolution of 3D reconstruction on the x-y plane is much higher than along the z-axis. To compensate for the imbalanced resolution in 3D, we use two light field cameras positioned at an orthogonal angle to capture particle images. In this way, we can achieve high-resolution 3D particle reconstruction in the full fluid volume. For each time frame, we first estimate particle depths under a single viewpoint by exploiting the focal stack symmetry of light field. We then fuse the recovered 3D particles in two views by solving a linear assignment problem (LAP). Specifically, we propose an anisotropic point-to-ray distance as matching cost to handle the resolution mismatch. Finally, given a sequence of 3D particle reconstructions over time, we recover the full-volume 3D fluid flow with a physically-constrained optical flow, which enforces local motion rigidity and fluid incompressibility. We perform comprehensive experiments on synthetic and real data for ablation and evaluation. We show that our method recovers full-volume 3D fluid flows of various types. Two-view reconstruction results achieves higher accuracy than those with one view only.

Layout optimization of an offshore floating wind farm deployed with novel multi-turbine platforms with the self-adaptive property

To deploy offshore wind in deeper waters, floating offshore wind confronts simultaneously significant opportunities and challenges. For dealing with the power deficit caused by the wake effect, a layout optimization method has been proposed for wind farms under variable wind conditions using the full-field wake model with the capacity to deploy multi-turbine platforms. The joint distribution of wind speed and direction is utilized to consider the variable wind conditions. The layout of an offshore wind farm, comprised of the floating platforms with multiple wind turbines and the wind-orientated ability, i.e., the self-adaptive property, is optimized under different wind conditions. Different numbers of turbines on a platform and platforms in the wind farm are deployed, respectively. The optimization results confirm that the platform with the self-adaptive property has a remarkable advantage to improve the efficiency of the wind farm. More turbines on a platform and less platforms can obtain higher efficiency. The distribution of wind speed and wind direction impacts the optimized layout and power output of the wind farm, simultaneously. The platforms arrange parallel lines which are perpendicular to the wind direction with more frequency and higher speed in the optimized wind farm. The concentration of the wind direction and the orthogonal angle between the wind and the long edge of the wind farm can increase the power output of the wind farm. However, the distribution of the wind speed has the dominant influence on the power output.

Research on the muzzle vibration displacement test method of large-caliber rifled gun based trinocular vision

To address the problem of inaccurate muzzle vibration displacement measurements caused by the twisting of the barrel at the moment of firing of large-caliber rifled gun, a vibration displacement test method of large-caliber rifled gun based trinocular vision is proposed. A high-precision measurement system for muzzle vibration displacement based on an orthogonal imaging method with three high-speed cameras has been built. Three high-speed cameras are placed at the side and rear of the gun at orthogonal angles to each other to collect two-dimensional digital images of the gun muzzle area. Accurate displacement of the muzzle height, azimuth and recoil direction is derived by image processing techniques and multi-dimensional displacement decoupling methods. In addition, the three cameras can realize the online self-verification of parameters such as ‘recoil’ and ‘twist’. The three-dimensional vibration displacement and torsion parameters of the muzzle of a 155mm gun were obtained by a test of firing range. The test results proved the validity and accuracy of the method for the muzzle vibration displacement of rifled gun.

Prediction of Contaminated Areas Using Ultraviolet Fluorescence Markers for Medical Simulation: A Mobile Phone Application Approach.

The use of ultraviolet fluorescence markers in medical simulations has become popular in recent years, especially during the COVID-19 pandemic. Healthcare workers use ultraviolet fluorescence markers to replace pathogens or secretions, and then calculate the regions of contamination. Health providers can use bioimage processing software to calculate the area and quantity of fluorescent dyes. However, traditional image processing software has its limitations and lacks real-time capabilities, making it more suitable for laboratory use than for clinical settings. In this study, mobile phones were used to measure areas contaminated during medical treatment. During the research process, a mobile phone camera was used to photograph the contaminated regions at an orthogonal angle. The fluorescence marker-contaminated area and photographed image area were proportionally related. The areas of contaminated regions can be calculated using this relationship. We used Android Studio software to write a mobile application to convert photos and recreate the true contaminated area. In this application, color photographs are converted into grayscale, and then into black and white binary photographs using binarization. After this process, the fluorescence-contaminated area is calculated easily. The results of our study showed that within a limited distance (50-100 cm) and with controlled ambient light, the error in the calculated contamination area was 6%. This study provides a low-cost, easy, and ready-to-use tool for healthcare workers to estimate the area of fluorescent dye regions during medical simulations. This tool can promote medical education and training on infectious disease preparation.

Echo-ID: Smartphone Placement Region Identification for Context-Aware Computing.

Region-function combinations are essential for smartphones to be intelligent and context-aware. The prerequisite for providing intelligent services is that the device can recognize the contextual region in which it resides. The existing region recognition schemes are mainly based on indoor positioning, which require pre-installed infrastructures or tedious calibration efforts or memory burden of precise locations. In addition, location classification recognition methods are limited by either their recognition granularity being too large (room-level) or too small (centimeter-level, requiring training data collection at multiple positions within the region), which constrains the applications of providing contextual awareness services based on region function combinations. In this paper, we propose a novel mobile system, called Echo-ID, that enables a phone to identify the region in which it resides without requiring any additional sensors or pre-installed infrastructure. Echo-ID applies Frequency Modulated Continuous Wave (FMCW) acoustic signals as its sensing medium which is transmitted and received by the speaker and microphones already available in common smartphones. The spatial relationships among the surrounding objects and the smartphone are extracted with a signal processing procedure. We further design a deep learning model to achieve accurate region identification, which calculate finer features inside the spatial relations, robust to phone placement uncertainty and environmental variation. Echo-ID requires users only to put their phone at two orthogonal angles for 8.5 s each inside a target region before use. We implement Echo-ID on the Android platform and evaluate it with Xiaomi 12 Pro and Honor-10 smartphones. Our experiments demonstrate that Echo-ID achieves an average accuracy of 94.6% for identifying five typical regions, with an improvement of 35.5% compared to EchoTag. The results confirm Echo-ID's robustness and effectiveness for region identification.

Study of the Movement of Chips during Pine Wood Milling

Circumferential milling is used in wood processing, yet it generates vast quantities of dust and chips in a single pass, highlighting the need to predict chip dispersion and prevent associated hazards. This article presents findings from a theoretical and experimental analysis of chip size and kinematics of pine wood during cutting. A chip diffusion boundary surface model was established and its key parameters were determined through CCD testing. Results reveal that chip diffusion can be divided into three distinct areas based on motion state: main diffusion, random diffusion, and vortex. Notably, spindle speed and feed rate are most influential on the orthogonal diffusion angle of the main diffusion zone, whereas cutting depth most heavily impacts the top view diffusion angle. Chip scattering on the table showed an exponential increase in average chip size with sampling distance, whereas the boundary surface model accurately characterizes chip motion and demonstrates a reasonable degree of reliability, offering potential in predicting chip morphology and diffusion state. This model has important implications for wood milling practices, particularly in controlling chip dispersion.

Integrative Study on Flow Characteristics and Impact of Non-Submerged Double Spur Dikes on the River System.

The flow characteristics around non-submerged spur dikes continuously placed in the channel on the same side with orthogonal angle to the wall were investigated by numerical simulations and experimental measurements. Three-dimensional (3D) numerical simulations with the standard k-ε Model for incompressible viscous flow based on finite volume method and the rigid lid assumption for free surface treatment were conducted. A laboratory experiment was applied to verify the numerical simulation. The experimental data indicated that the developed mathematical model can effectively predict 3D flow around non-submerged double spur dikes (NDSDs). The flow structure and turbulent characteristics around them were analyzed and it was found that a distinct cumulative effect of turbulence exists between the dikes. By examining the interaction rules of NDSDs, the judgment criterion of spacing threshold was generalized as whether velocity distributions at the cross-sections of NDSDs along the main flow approximately coincided or not. It can be used to investigate the impact scale of the spur dike groups on the straight and prismatic channels and it is of great significance for artificial scientific river improvement and the assessment of river system health under human activities.

Image restoration for blurry optical images caused by photon diffusion with deep learning.

Optical macroscopic imaging techniques have shown great significance in the investigations of biomedical issues by revealing structural or functional information of living bodies through the detection of visible or near-infrared light derived from different mechanisms. However, optical macroscopic imaging techniques suffer from poor spatial resolution due to photon diffusion in biological tissues. This dramatically restricts the application of optical imaging techniques in numerous situations. In this paper, an image restoration method based on deep learning is proposed to eliminate the blur caused by photon diffusion in optical macroscopic imaging. Two blurry images captured at orthogonal angles are used as the additional information to ensure the uniqueness of the solution and restore the small targets at deep locations. Then a fully convolutional neural network is proposed to accomplish the image restoration, which consists of three sectors: V-shaped network for central view, V-shaped network for side views, and synthetical path. The two V-shaped networks are concatenated to the synthetical path with skip connections to generate the output image. Simulations as well as phantom and mouse experiments are implemented. Results indicate the effectiveness of the proposed method.

Halocyclopropenium‐Halide Halogen‐Bonded Ion Pairs and Their Hydrogen‐Bonded Halide Solvates

AbstractA series of salts with a diaminohalocyclopropenium cation and halide anion [C3(NiPr2)2X]X (X=Cl ([1]Cl) or Br ([2]Br) were isolated with a variety of solvates and, in one case, as a co‐crystal with hydronium chloride. In particular, the initial synthesis of [1]Cl formed a co‐crystal with hydronium and with CH2Cl2 solvate ([1]2[OH3Cl3] ⋅ CH2Cl2) upon isolation from acetone/CH2Cl2. Recrystallization of this from chloroform gave a dichloroform adduct [1]Cl ⋅ 2CHCl3, whereas treatment with ICl formed an octahalide cluster [1]2I4Cl4. The bromine salt [2]Br ⋅ C2H4Br2 was prepared by treatment of [1]Cl with dibromoethane and was isolated as a solvate. The hydronium cation was found as part of a hydronium trichloride cluster [OH3Cl3]2− and this, along with a partially‐deuterated analogue of [OHD2Cl3]2− and [OD3Cl3]2−, was studied computationally and by mid‐ and far‐infrared spectroscopy. Significant halogen bonds were found between 1+ or 2+ and chloride or bromide, respectively. On the other hand, the distance to the octahalide [I4Cl4]2− is too long for a halogen bond. Hydrogen bonding from the halides to the halomethane solvates is also significantly stronger than to the cation isopropyl groups. The geometries formed at the halide ions with respect to the halogen bond and strong hydrogen bonds are pyramidal with approximately orthogonal angles.

Reconstruction algorithm of haze image based on blind separation model of polarized orthogonal airlight.

Polarization-based dehazing methods can enhance the quality of haze images. However, existing methods tend to a manual selection of sky area and bias coefficient to estimate the degree of polarization (DoP) of the airlight, which leads to inaccurate estimation of the airlight. Aiming at the problem, a reconstruction algorithm based on the blind separation model of polarized orthogonal airlight is proposed. Importantly, the depth-dependent DoP of the airlight is automatically estimated without manual selection of sky area and bias coefficient. To reduce the interference of white objects on the estimation of airlight at infinity, an adaptive estimation method using the deviation between the DoP of the airlight and incident light is proposed. In order to accurate estimate the airlight from the airlight at infinity, a blind separation model of the airlight with multi-regularization constraints is established based on the decomposition of the airlight at infinity into a pair of polarized components with orthogonal angles. The experimental results show that the method effectively improves the visibility of scenes under different haze concentrations, especially in dense or heavy haze weather.

Effect of Twisting Phases on the Polarization Dynamics of a Vector Optical Field

The effect of twisting phases on the polarization dynamics of a vector vortex beam with a spatially variant state of polarization (SoP) is investigated theoretically and experimentally. The twisted vector vortex optical field with the cross-phase modulation is experimentally generated and observed. The presence of the twisting phases on the vector optical field results in novel propagation dynamics and the evolution of polarization states. The optical field performs the process of compressing and stretching the orthogonal polarization components and the linear-circular polarization conversions during propagation. Different from the scalar twisted beams, the orthogonal polarization components of twisted vector beams can be compressed along the same azimuthal angle or the orthogonal azimuthal angles, depending on the signs of the twist intensity coefficients. For an anisotropic twisted optical field, the SoP and the optical field rotate, and the rotation behaviors are sensitively dependent on the twisting coefficients. Furthermore, the two vortex topological charges embedded within the orthogonal polarization component of a twisted vector vortex beam can be simultaneously identified by looking at the interference fringes of the twisting phases. This work reveals that a vector vortex beam and its SoP can be dynamically manipulated by twisting phases.

"TOOL-IN-LESION” ACCURACY OF GALAXY SYSTEM: ROBOTIC-ASSISTED, ELECTROMAGNETIC NAVIGATION BRONCHOSCOPY WITH INTEGRATED TOOL-IN-LESION-TOMOSYNTHESIS TECHNOLOGY: THE MATCH STUDY

"TOOL-IN-LESION” ACCURACY OF GALAXY SYSTEM: ROBOTIC-ASSISTED, ELECTROMAGNETIC NAVIGATION BRONCHOSCOPY WITH INTEGRATED TOOL-IN-LESION-TOMOSYNTHESIS TECHNOLOGY: THE MATCH STUDY

Enhanced Red Persistent Room-Temperature Phosphorescence Induced by Orthogonal Structure Disruption during Electronic Relaxation.

Bright, persistent, room-temperature phosphorescence (RTP) at long wavelengths is crucial for high-resolution imaging in the absence of in vivo autofluorescence. However, efficient long-wavelength RTP is difficult. Here, enhanced red RTP based on a unique mechanism was observed from deuterated dibenzo[g.p]chrysenes substituted with a phenoxazine. The yield was 16%, with an average lifetime of 1.8 s. An orthogonal dihedral angle between the dibenzo[g.p]chrysene and the phenoxazine in the lowest excited singlet state allowed a forbidden fluorescence to increase triplet generation. When the dihedral angle changed, disengagement of the forbidden fluorescence from the excited singlet state occurred, and the lowest triplet excited state had a facilitated phosphorescence rate without increasing its nonradiative transition rate. The facilitated phosphorescence rate as well as the large triplet yield led to the enhanced red RTP.

Accurate and Early Metastases Diagnosis in Live Animals With Multimodal X-ray and Optical Imaging

In vivo optical imaging systems are essential to track disease progression and evaluate therapeutic efficacy in animal studies. However, current approaches are limited by their inability to accurately capture 3-dimensional (3-D) image information. To overcome this hindrance, we adopted x-ray computed tomography (CT) as a prior for 3-D optical image reconstruction and further challenged the multimodal imaging performance with a metastasis model. The iSMAART system, an integrated small animal research platform, features coregistered high-quality quantitative optical tomography and CT. In the synergistic dual-modality imaging, CT provides both 3-D anatomy information and animal structure mesh for optical tomography reconstruction, which is performed using bioluminescence projections acquired from 4 orthogonal angles. The multimodal imaging system was challenged with a prostate cancer metastasis model, and a double-blind histopathology diagnosis was obtained to validate the imaging results. The iSMAART located, visualized, and quantified early tumor metastases at the millimeter scale, and can accurately track deep tumors as small as 1.5 mm in live animals. Tumors metastasized into the liver, diaphragm, and tibia in 4 mice were all successfully diagnosed by the integrated tomographic imaging. Instead of roughly comparing surface-light intensities, as traditionally performed in 2-dimensional optical imaging, iSMAART provides accurate tumor imaging and quantitative assessment capabilities with integrated CT and optical tomography for cancer metastasis research. With the powerful 3-D optical/CT imaging capability, iSMAART has the potential to tackle more complex research needs with higher targeting accuracy.

Underwater fish mass estimation using pattern matching based on binocular system

Fish mass is the main information for judging growth status, regulating water quality environment, and precision feeding and grading in the process of intelligent aquaculture management activities. However, the occlusion, bending, and poor imaging angle of fish body image are still serious challenges for underwater fully automatic mass measurement. The aim of this study was to develop underwater non-contact method to automatically estimate the free-swimming fish mass based on binocular stereo vision technology. The fish body images were automatically selected and obtained by using pattern recognition method based on LabVIEW development platform during the experimental period. All the fish samples were divided into three groups according to mass (200–500 g, 500–800 g, and 800–1200 g), and then subdivided into three groups by imaging angle (orthogonal angles, greater than 45°, and less than 45°). The experiment indicated that the fish mass could be estimated using fish body area with a high coefficient of determination (R2) based on linear model. The mean relative errors between estimated and measured value were 3.37% (orthogonal angles), 4.95% (greater than 45° angles), and 16.59% (less than 45° angles). Significant difference was found in less than 45° group with p < 0.01. These findings showed that the approach put forward in this research could realize fully automatic mass estimation for underwater free-swimming fish and effectively improve the estimation robustness and efficiency.