Angle Spread Research Articles

First Detailed Study of the Quantum Decoherence of Entangled Gamma Photons.

Constraints on the quantum decoherence of entangled γ quanta at the mega-electron-volt scale, such as those produced following positron annihilation, have remained elusive for many decades. We present the first statistically and kinematically precise experimental data for triple Compton scattering of such entangled γ. An entanglement witness (R), relating to the enhancement of the azimuthal correlation between the final scattering planes, is obtained where one of the γ underwent intermediate Compton scattering. The measured R, deconvolved from multiple scattering backgrounds, are found to exceed the classical limit for intermediate scatter angles up to ∼60° and diminish at larger angles. The data are consistent with predictions from a first quantum theory of entangled triple Compton scattering as well as a simple model based approach. The results are crucial to future study and utilization of entangled mega-electron-volt γ in fundamental physics and positron emission tomography imaging.

Internal friction setting depending on the particle shape

Research into the properties of input materials and the setup of equipment for polymer process technology is the first step in any development and innovation. Considering the requirements of reducing energy consumption, time and recyclability of materials, it is desirable to develop a tool for setting the mechanical and physical properties of binary mixtures of plastic granulates. Therefore, a dataset containing the particle size distribution, internal friction angle and spreading angle of eight different polymer granulates and their blends was created. If the internal angle of the material does not suit the technology, there is the possibility to change the technology itself or to modify the material passing through the technology at the input. It is also important to know the dependence of particle shape on internal friction. Based on the measured mixing values of the plastic granules, a dataset was created from which the computer program can draw input data to generate a new mixture setting for the desired friction value. Knowing the ingredient ratios to set the desired friction is the technology of the future. Once the input shape parameters of the individual components in the mixture have been given, the model can also be used in reverse, where in turn an idea of the internal friction angles of the input mixture components can be obtained.

Support Vector Machine Framework for Detecting Ambiguous Contours of Space Debris Cloud

Operational spacecraft are prepared for collisions with space debris by installing protective walls (bumpers). A group of vaporized and liquefied microparticles generated by debris collisions is called a debris cloud. To evaluate the protective performance of bumpers, it is important to measure the spread velocity and angle of the debris cloud. However, debris cloud images exhibit ambiguous contours of debris clouds. Consequently, measurement errors in the spread velocity and spread angles occur because of the observer’s subjectivity. Commonly used derivative-based methods can detect steep contours; however, they cannot detect ambiguous contours such as those of debris clouds. In this study, a method for uniquely detecting the ambiguous contours of a debris cloud based on supervised machine learning and a continuous wavelet transform (CWT) is proposed. Feature points that indicate candidate points of the debris cloud contour are extracted using a method based on CWT. Four types of specific features for debris cloud contours were assigned to the feature points. Supervised machine learning using a support vector machine can detect the debris cloud contours. The proposed method enables the evaluation of the ambiguous contours of a debris cloud and the protection performance of a bumper without observer subjectivity.

Influence of thermodynamic conditions on the mixing characteristics of a supercritical nitrogen jet under mode excitation

Fuel injection mixing is one of the critical factors affecting the energy conversion efficiency and emission level of thermal engines. The effect of thermodynamic conditions on mixing characteristics of supercritical cryogenic nitrogen jet under varicose mode excitation is investigated using the unsteady Reynolds-averaged Navier-Stokes method combined with real-gas thermodynamics and transport properties of nitrogen in NIST database. The ambient-to-jet density ratio is defined to represent different thermodynamic conditions and is found to affect the jet mixing enhancement directly. As the density ratio increases from 0.098 to 0.432, the density gradient reduces in the jet shear layer, mitigating flow stratification. Jet mixing is enhanced with a reduction of density potential core length by 24 % and a tripled density spreading angle. Under varicose mode excitation, large vortices are formatted close to the jet orifice, especially for higher density ratio cases. The peak of the jet turbulent kinetic energy is higher and shifts upstream as density ratio increasing. The jet mixing enhancement is further achieved, with the spreading angle increment growing from 1° to 4° and the velocity decay rate increasing from 0.03 to 0.15. As the excitation amplitude rising from 5 % to 15 %, the growth of jet momentum instability in the jet potential core breaks the velocity gradients inhibition on jet mixing. The supercritical jet enters self-similar region earlier, with density potential core length shortened by 51 % and spreading angle increased by 28 % at a middle density ratio of 0.275.

Reproducibility evaluation of detailed directional spectrum based on mean spreading angle for ship performance estimation in actual seas

Reproducibility evaluation of detailed directional spectrum based on mean spreading angle for ship performance estimation in actual seas

Characteristics of Supersonic Sweeping Jet with Geometry Variation of Actuator Exits

Supersonic sweeping jets (SWJs) have demonstrated their effectiveness across a variety of scenarios, particularly in aeronautic applications (e.g., lift enhancement). An experimental study is conducted to investigate the characteristics of SWJs emitted from actuators with different spreading angle θ and exit length l. Schlieren visualization is used to capture the near- and far-field SWJs at nozzle pressure ratios (NPRs) ranging from 1.6 to 6.9. The results show that as NPR increases the SWJs become underexpanded when l≠0. Different θ have an impact on the shock structure and the law of the spreading angle of jet control area α changing with NPR. When θ is approximately 100 deg, α increases at first and then decreases with increasing NPR, reaching up to 90 deg at high NPRs. When θ is about 50 deg, α remains roughly constant and equal to θ. Internal flow measurements reveal that flow attachment caused by the Coanda effect plays a significant role in the mechanism that leads to a change in α. Proper orthogonal decomposition is applied to analyze the spatial and temporal patterns. Far-field measurements show multiple sound waves propagating upstream and downstream, which generated by the supersonic SWJs.

Multipath Angle Spread and Performance in Indoor Measured Tri-Polarized Massive MIMO Channels

Multipath Angle Spread and Performance in Indoor Measured Tri-Polarized Massive MIMO Channels

Molecular origin of the plasticizing effect difference of glycerol with other polyols on plasticizing polyvinyl alcohol (PVA) as elucidated by solid-state NMR

Glycerol has been proved to be an effective plasticizer for polyvinyl alcohol (PVA), which can significantly increase PVA’s processability and ductility, whose molecular origin remains unclear. In current study, the physical structure and chain dynamics of polyol plasticized PVA were studied in detail, including ethylene glycol, glycerol, erythritol, xylitol, and sorbitol under the same addition level. The glycerol plasticized PVA exhibits the most significant reduction in Young’s modulus, enhanced superior toughness, and the lowest melting temperature (195 °C) as compared with other polyols. The molecular mechanism was elucidated through comprehensive analysis, with a particular focus on solid state NMR (SS NMR) results. The physical structure was first elucidated by the Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS). The crystallinity of the glycerol plasticized PVA was the lowest 29 % by WAXS and the thickness of the amorphous layer was the largest 7.76 nm by SAXS among different plasticized PVA films. This suggests the significant influence of glycerol on structure change of PVA. The molecular dynamics information was further accessed by Low Field Nuclear Magnetic Resonance (LF NMR), where two key features are obtained: i) Different dynamics dimensionality. The 1H spin diffusion NMR was used to check the dimensionality from the aspect of chain dynamics. Compared with other plasticizers, LF NMR result shows that glycerol plasticized PVA has a two-dimensional (2D) structure; ii) Chain dynamics heterogeneity in the interphase. With respect to the chain dynamics heterogeneity in the interphase, the glycerol plasticized PVA shows the most heterogeneous dynamics, with the lowest ratio of the rigid amorphous fraction (RAF) of 0.507 in the interphase. Current study provides a versatile analytical strategy to quantify the plasticizing effect.

Benchmarking predictive methods for small-angle X-ray scattering from atomic coordinates of proteins using maximum likelihood consensus data.

Stimulated by informal conversations at the XVII International Small Angle Scattering (SAS) conference (Traverse City, 2017), an international team of experts undertook a round-robin exercise to produce a large dataset from proteins under standard solution conditions. These data were used to generate consensus SAS profiles for xylose isomerase, urate oxidase, xylanase, lysozyme and ribonuclease A. Here, we apply a new protocol using maximum likelihood with a larger number of the contributed datasets to generate improved consensus profiles. We investigate the fits of these profiles to predicted profiles from atomic coordinates that incorporate different models to account for the contribution to the scattering of water molecules of hydration surrounding proteins in solution. Programs using an implicit, shell-type hydration layer generally optimize fits to experimental data with the aid of two parameters that adjust the volume of the bulk solvent excluded by the protein and the contrast of the hydration layer. For these models, we found the error-weighted residual differences between the model and the experiment generally reflected the subsidiary maxima and minima in the consensus profiles that are determined by the size of the protein plus the hydration layer. By comparison, all-atom solute and solvent molecular dynamics (MD) simulations are without the benefit of adjustable parameters and, nonetheless, they yielded at least equally good fits with residual differences that are less reflective of the structure in the consensus profile. Further, where MD simulations accounted for the precise solvent composition of the experiment, specifically the inclusion of ions, the modelled radius of gyration values were significantly closer to the experiment. The power of adjustable parameters to mask real differences between a model and the structure present in solution is demonstrated by the results for the conformationally dynamic ribonuclease A and calculations with pseudo-experimental data. This study shows that, while methods invoking an implicit hydration layer have the unequivocal advantage of speed, care is needed to understand the influence of the adjustable parameters. All-atom solute and solvent MD simulations are slower but are less susceptible to false positives, and can account for thermal fluctuations in atomic positions, and more accurately represent the water molecules of hydration that contribute to the scattering profile.

Effect of airflow rate on droplet deposition of an impinging-jet inhaler in the human respiratory tract

This paper presents a numerical investigation to understand the transport and deposition of sprays emitted by an impinging-jet inhaler in the human respiratory tract under different inhalation flow rates. An injection model is used for the numerical simulations considering the spreading angles of the spray in the two directions, which are measured from experiments. The model parameter is adjusted to match the mean droplet size measured in the previous experiment. A time-varying sinusoidal inhalation flow rate is utilized as airflow conditions, which is closer to the actual situation when using an inhaler. The results demonstrate that the inhalation airflow rate significantly affects the spray’s transport behavior and deposition results in the respiratory tract. Both excessively high and low inhalation flow rates lead to an increase in deposition in the mouth-throat. A moderate inhalation flow rate reduces throat deposition while maximizing lung deposition. Higher inhalation flow rates enable faster delivery of the droplets to the lungs, whereas lower inhalation flow rates achieve a more uniform deposition over time in the lungs. The amount of deposition in different parts of the lung lobes follows a fixed order. This study provides valuable insights for optimizing the inhalation flow rate conditions of the impinging-jet inhaler for clinical applications.

An experimental study on the combustion characteristics of the cavity-stabilized supersonic premixed flame

With the overwhelming trend of fast and economic aviation, it is becoming increasingly difficult for fuel to burn stably and efficiently in a constrained space and time period in the combustor of a hypersonic air-breathing vehicle. Conventional supersonic diffusion flame runs the risk of blowing out in the incoming flow at such high velocity. Upstream fuel injection of the flame holder is gaining popularity due to its prominent advantage in improving mixing efficiency, and this fuel injection method contributes to the organization of supersonic premixed combustion. In order to study the combustion characteristics of the supersonic premixed flame, corresponding experiments are carried out on a direct-connected scramjet platform with the inflow total temperature of 1700 K and the inflow Mach Number of 2.0. Gaseous ethylene with an equivalence ratio of 0.15 was injected transversely 670 mm upstream of a cavity. Optical measurements including laser-induced fluorescence on the hydroxyl radical (OH-LIF), CH*chemiluminescence photography, and high-speed photography were performed to investigate the steady-state and transient combustion characteristics of the cavity-stabilized supersonic premixed flame. From steady-state OH-LIF and CH* results, the flame could be divided into reactant zone, preheating zone, intense reacting zone, and product zone. It could be inferred that the preheating zone induced by the hot product in the cavity acts as a radical source and heat source for combustion stabilization in the cavity. In addition, the transient flame morphology analysis was carried out from the high-speed photography results. The flame base position and flame spreading angle were abstracted from the binarized image. The results showed that there existed a subtle flame flashback phenomenon for the flame base, whereas the flame spreading angle maintained a relatively constant value with a small deviation. The frequency-domain analysis revealed that both the flame base position and flame spreading angle reached the peak amplitude in the direct current component (0 Hz), exhibiting no explicit high-amplitude resonance component within 1500 Hz compared to those in the diffusion combustion mode. In all, the supersonic premixed flame presented a stabilized flame morphology.

Suppression mechanism of transient pressure during the turbine runaway of an ultra-high head pump-turbine

Abstract Pressure fluctuation (PF) is a serious issue in transitions of the ultra-high head (UHH) pump-turbines (PTs). To explore the mechanism and control method of PF, the turbine runaway process (TRP) of an UHH PT was simulated using the one- and three-dimensional coupled method. The study suggested that the local backflow (BF) near the high-pressure (HP) inlet of the impeller blocked the impeller channel and induced water hammer. The local BF near the HP inlet of the impeller were closely related to the ratio of rotational speed to PT head. To suppress the BF this study proposed an improved impeller channel with 5 degree spread angle in meridian plane. The study found that the increase of rotational speed and transient pressure variations induced by water hammer could be suppressed successfully by using the improved impeller. The study provided important reference for the design and optimization of the UHH PTs.

Characterizing the internal wave wakes and synthetic aperture radar image features of underwater moving objects

In this study, a refined and improved theoretical model was proposed for calculating the synthetic aperture radar (SAR) images of internal wave wakes. This model was based on an equivalent source model of internal wave wakes and the velocity-bunching principle. Wake field, scattering field, and SAR image characteristics were systematically calculated for multiple scenarios. The model described the transfer and solution processes by inputting the background flow field temperature and salinity profiles to map the radar image intensity distribution. The physical mechanisms of the internal wave wake generation and its capture by SAR were comprehensively explained. The effects of various parameters on the internal wave wake SAR images were analyzed comprehensively. The SAR image features containing internal wave wakes were determined based on the gray-level co-occurrence matrix and image power spectrum, which revealed that the maximum surface current induced by the internal wave modes of the same amplitude was considerably larger than that induced by surface-wave mode. When traveling far from the water surface, the rate of change in the total scattering coefficient because of the Bragg effect was approximately 20 times that of the slope effect. In SAR images, the recognizability of wakes depends primarily on the maximum intensity rather than the average disturbance on the sea surface. Therefore, SAR images exhibit considerable differences during downwind radar observations, with the most prominent contrast differences occurring at the maximum spreading angle of wake scattering and 1500 m behind underwater objects. In the image power spectrum, the frequency range of the first modal internal waves was approximately 10–30 Hz, whereas the higher-order modal internal waves had frequencies lower than 10 Hz. Furthermore, the frequency range of the surface-wave mode was larger than that of internal-wave modes, approximately 50–60 Hz.

Исследование физико-механических свойств сгущенных хвостов обогащения и формируемого искусственного массива в выработанном пространстве карьера

The article presents the results of studying physical and mechanical properties of thickened concentration tailings, as well as regularities in their changes during the dumping process in mined-out spaces of open-pits. The necessity of experimental studies is explained by the existing discrepancy between the parameters of the artificial hydraulic deposition of soils and the design solutions, in particular, the spreading angles, the lack of a ponding zone created within the rock mass body, as well as the insignificant influence on the intakes of the dewatering plant. The following characteristics of the thickened tailings that define the parameters of the hydraulic deposition technology and the artificial massif formed inside the pit at the design stage were taken as the research objects: density, mineral density, absolute and relative moisture content, storactivity, viscosity, shear stress, flowing angle, and water conductivity. These characteristics were tested using conventional methods. Representative samples were collected at the discharge points of the thickened tailings in the open pit and directly at the discharge point of the thickener No.2 at the paste thickening plant. It was established that as the thickened tailings are transported to the place of their deposition inside the open pit, no changes take place in their density, moisture content, and water conductivity, but the rheological properties, such as viscosity, shear stress, angle of spreading undergo a significant change, which should be taken into account in design solutions. Being familiar with the technology of thickening, transportation and storage of paste mixtures in open-pit mines allows us to consider the mechanical impact on the pulp flocculi and their destruction, consisting in the rupture of the macromolecules, as the main cause of changes in the structure and properties of the thickened tailings.

Accuracy improvement of inner defects of cylindrical components using ultrasonic detection with modified ALOK method

The accuracy of defect localisation and its size quantification is poor in the detection of internal defects of cylindrical components using the ultrasonic Amplituden und Laufzeit Orts-Kurven (ALOK) method. The influence of acoustic beam spread is not taken into consideration in the ultrasonic ALOK method, resulting in difficulties with the precise characterisation of the defect state. To address this, the relationship between the acoustic distance, amplitude, ultrasonic frequency, size and depth of hole defects was studied. The acoustic distance curve and the amplitude curve were fitted and then the localisation model of the defect was obtained. The acoustic beam spreading angle and echo sound pressure were introduced and then the size quantification model for defects was acquired based on principal component analysis (PCA). Both the simulated and experimental results show that the modified ALOK algorithm improved the detection accuracy of the defect location and its size and the relative error of defect sizing decreased by more than 35% compared with the original algorithm.

Numerical simulation study of the injection characteristics affecting trans-/supercritical sprays based on orthogonal experiment design

A mixture of numerical models and orthogonal experiments was used to better understand the mixing behavior and heat/mass transfer in jets operating under supercritical conditions. The goal is to investigate the effects of injector diameter (Dinj), ambient pressure (Pamb), injection temperature (Tinj), injection velocity (Vinj), and ambient temperature (Tamb) on jet evolution. The findings highlight that, among these parameters, Tinj and Dinj exert the most substantial impact on jet mixing characteristics. Higher Tinj and Dinj enhance the jet spreading angle (θhsa) and mixing layer thickness (δ) for improved mixing efficiency. Increasing Tinj and reducing Dinj effectively shorten the potential core length (Lp). Moreover, higher Tinj enhances the temperature rise rate (Tr), effectively raising fuel temperature over a shorter distance. The velocity decay rate (Vd) increases with Vinj and Tinj. Furthermore, this study explores the effects of injection density ratio on evaluation indexes (θhsa, Lp, Vd, Tr and δ) for jet mixing efficiency and trends of jet structural development (Lp, turbulent chaos length (CL) and self-similarity length (SL)). These findings are important for understanding supercritical spray development, guiding engine chamber design and setting operational conditions based on spray behavior.

Design of birch plywood as gusset plates in timber-timber uniaxial tension connections: Influence of fastener pattern, face grain orientation, and discussions based on the Whitmore effective width theory

This study reveals timber-timber composite joints consisting of glulam pieces and birch plywood plates with three different load-to-face grain angles. Utilizing a similar number of fasteners and arranging the fastener array from narrow to wide, uniaxial tension specimens were manufactured with four different fastener patterns. The thickness of birch plywood was intentionally under-designed so that the failure modes for all connections were net tension failure of birch plywood plates. Thereafter, the influence of the fastener pattern and face grain orientation on the load-bearing capacity and stiffness of the investigated composite joints was studied. The load capacity and nominal strength generally increased when the nail patterns varied from narrow to wide. This observation was associated with the Whitmore effective width theory (load spread angle) in steel gusset plate design. Moreover, to derive valid analytical methods to predict the net-tension capacity of birch plywood plates, the classic spread angle model that assumes rectangular stress blocks and the modified spread angle model that considers the summation of stresses from each fastener row were discussed. Both models were adopted to predict the net tension capacity of investigated specimens at 0°. In addition, the stiffness of joints was measured and compared with slip modulus formulas in Eurocode 5. The measured local stiffness values were found to be independent of the fastener pattern and load-face grain angles. The analytical slip modulus assuming the case without predrilling exhibited a satisfactory prediction, while formulas assuming the case with predrilling tend to give overestimations.

Sophisticated Attenuated Total Reflection Correction Within Seconds for Unpolarized Incident Light at 45°.

The most common mid-infrared (MIR) attenuated total reflection (ATR) accessory has a nominal angle of incidence of 45° and does not have a polarizer. A spectrum recorded with such an accessory does not hold enough information for the sophisticated ATR correction of MIR spectra with strong peaks, which are often strongly affected by refractive index changes due to anomalous dispersion. Here we show that a 45° ATR spectrum recorded without a polarizer and the polarization angle for the same ATR Fourier transform infrared spectroscopy system provide enough information to determine the ATR s-polarized spectrum. Further analysis with an improved non-iterative Kramers-Kronig analysis immediately yields the complex refractive index function. The analysis is about two orders of magnitude faster than iterative formalism and runs within seconds on a typical office PC. The effectiveness of our advanced ATR correction formalism is showcased through its application to water, employing diamond, ZnSe, and Ge ATR crystals, along with two distinct ATR accessories. Additionally, the formalism is applied to octadecane spectra. Potential sources of errors such as incidence angle spread, dispersion of the polarization angle, and the influence of reflection at the air/ATR crystal interface are investigated by simulations.

Process parameters and their effect on metal transfer in gas metal arc welding: a driving force perspective

AbstractIn gas metal arc welding (GMAW), the optimization of process parameters and the control of metal transfer is pivotal for achieving superior welding outcomes. This study meticulously examines the roles of core process parameters in metal transfer: wire extension and arc geometry, which includes arc length and inter-cathode distance. Using a unique MIG-based non-transferred arc system with symmetrically arranged tungsten cathodes we have achieved distinct control over wire feed rate and arc geometry, independent of the arc current. We investigate the interplay of these parameters and their consequential influence on the driving forces governing metal transfer. While increasing the wire extension enhanced inertial forces, it did not lead to consistent transitions in the metal transfer modes. In contrast, adjusting arc length and inter-cathode distance effectively controlled the electromagnetic force acting on molten droplets, as quantified by the arc spread angle $$\theta$$ θ . Notably, an increase in the arc spread angle resulted in the elongation of molten droplets. This study clarifies the fundamental relationships between driving forces and process parameters in GMAW. Additionally, it introduces a more advanced evaluation model for electromagnetic force and offers a comprehensive strategy for refining welding control techniques.

STRUCTURAL OPTIMIZATION OF JET PUMP BASED ON BP NEURAL NETWORK

With the increasing drilling depth, problems follow, such as the lifting height of the liquid in the well and increased pump operation. Therefore, improving the production efficiency of deep wells is a hot spot in the current oil drilling and production industry. This paper designs a new jet pump that can be mined for high and low-pressure oil layers according to the oil wells’ inter-layer contradiction. The FLUENT software is used to simulate the new jet pump, analyze the pump efficiency factors of the jet pump and the physical properties of the fluid, and the BP neural network is used to optimize the structure of the jet pump. The results show that the maximum pump efficiency of spout distance, duct diameter, duct distance, and spread angle is 2.61-5.22 mm, 6.393-8 mm, 42.5-53.2 mm, and 6-9°, respectively. The best spout distance, duct diameter, duct distance, and spread angle are 2.74 mm, 6.80 mm, 46.5 mm, and 7.4°after being optimized by the BP neural network model presented in this paper and the optimized pump efficiency is improved by 9.45%.