Calculation Of Propagation Research Articles

Mathematical methods in studying temperature-time conditions of the friction surfacing in the manufacture of functionally organized steel-aluminum compositions

A mathematical model for studying temperature and time conditions of the process of friction surfacing in the manufacture of functionally organized steel-aluminum compositions has been developed and validated. Bars made of pure aluminum grade ER1100 were used as the consumable rod material during friction surfacing. The substrate in the form of a rectangular plate was made of high-quality steel 20. The geometric model of the object when modeling the process of friction surfacing in the ANSYS 2021R2 software package was specified in the form of a rod and a substrate. The initial data for calculating temperature-time conditions of the friction surfacing process are: geometric parameters of the simulation object; characteristics of thermal loads of the heating source which depend on the technological parameters of the surfacing mode (the speed of axial rotation of the rod, axial pressure, boundary conditions of the simulation object for the temperature problem), and auxiliary parameters that determine the order of calculations. The thermal power arising at the point of physical contact between the rotating consumable rod and the substrate was considered a parameter of the source thermal load. The calculation of heat propagation for the friction surfacing process was carried out according to a scheme with a normally circular source located on the substrate surface. The calculation scheme directly reflects the main feature of the friction surfacing process: the introduction of heat due to friction between the rotating consumable rod and the substrate. It is shown that taking into account the boundary conditions and geometric features of the 3D model provide a satisfactory convergence of developed mathematical model and ensure the uncertainty of no more than 5 % in determining the heating temperature of the substrate when forming functional aluminum coatings, as well as composite materials on their base when surfacing them on the surface of steel substrates.

Numerical study on aerodynamic drag and noise of high-speed pantograph by introducing spanwise waviness

It is noteworthy to explore potential measures for further reducing the aerodynamic drag and noise of high-speed pantographs. This paper proposes a method of introducing spanwise waviness into the upper and lower arms. The improved delayed detached eddy simulation (IDDES) method and the Ffowcs Williams and Hawkings (FW-H) equation are used for flow field simulation and sound propagation calculation, respectively. The effects of wavelength, wave amplitude and inclination on the aerodynamic force and radiated noise of the wave cylinder were firstly investigated, and then the aerodynamic characteristics of the pantograph with and without spanwise waviness configurations were compared. Results show that the appropriate spanwise waviness on the cylinder can diffuse the negative pressure core area in the wake, reduce the negative pressure amplitude, suppress the vortex shedding and weaken the fluctuation amplitude of the aerodynamic force, resulting in the reduction of aerodynamic drag and noise. For the high-speed pantograph by introducing spanwise waviness, when the ratio of wavelength and wave amplitude to cylinder diameter is 1.2 and 1/8 respectively, the aerodynamic drag and noise of the pantograph by introducing spanwise waviness are reduced by 1.58% and 1.16 dBA, respectively.

Surrogate model building and error analysis for the damage tolerance life of penetration type fatigue crack

The penetration type cracks are often found in the components of mechanical systems and are a major threat to the operational reliability of mechanical components. There are many factors affecting the fatigue crack damage tolerance life, so the numerical calculation of 3D fatigue crack propagation is a complex process. Therefore, it is significant to improve the calculation efficiency of fatigue crack life with guaranteeing the calculation accuracy. The crack life is the result of the integration of crack propagation length and stress intensity factor(SIF). In this paper, a surrogate model for calculating the damage tolerance life of penetrating fatigue cracks is constructed using Kriging method based on the results of experimental tests and finite element analysis(FEA). The surrogate model is a four-dimensional response-value solution model, which can solve the fatigue crack life under random parameters. Finally, an error analysis is performed on the results of the surrogate model calculation. The results indicate that the error of the surrogate model calculation is relatively low, and the overall error is within 2%. Therefore, the surrogate model is characterized by high efficiency and accuracy.

Fracture-mechanical crack growth parameters of historical mild steels

At the beginning of the 20th century, a large number of steel structures were built in Europe. Many of these buildings—especially railway bridges—are still in use. These structures are mainly composed of rimmed steel. In addition to the stress–life concept, fracture mechanics is often used to assess the safety of these structures in terms of fatigue failure. Based on crack propagation calculations, it is possible to determine inspection intervals and, thus, ensure safe operation. For these calculations, suitable parameters of the Paris law, along with threshold values, are needed. The aim of this study is to experimentally determine a wide range of fracture mechanics parameters for old mild steel with reference to the stress ratio R. The experimental results were compared with values from the literature. Furthermore, the experimental results were fitted to several models considering the stress ratio R during crack growth. The investigated models were compared on the basis of the results for simulated crack growth calculations. The models are assessed according to how closely they represent the experimental results.

Ptychographical iterative engine based on pixel binning for improving the computational efficiency

Ptychographical iterative engine (PIE) is an attractive modality of phase retrieval that can provide the quantitative phase of the sample and extend the field of view. For a large sample, a great deal of images with a large dataset are recorded, which will result in high requirements for the computing power and increase the calculation burden. Here, we propose a pixel binning strategy to improve the computational efficiency and reduce the calculation time of PIE. In this method, the recorded image chosen as the amplitude constraint in reconstruction algorithm is compressed by merging the amplitude values of the adjacent positions into one value by the linear superposition, and the compressed pattern is set as a new amplitude constraint to reconstruct the compressed object and probe with fewer pixel number and larger grid size compared to the uncompressed results. Then, the compressed values are extended by the interpolation method. The improvement in the computational efficiency at the point lies in the fact that it takes less time to do the free-space diffraction propagation calculation for images with fewer pixel number. Experiments demonstrate that the proposed method behaves good performance with high computational efficiency. The proposed approach would be helpful for large-scale imaging with high computational efficiency.

Simultaneous Inversion of Ocean Bottom Pressure and Electromagnetic Tsunami Records for the 2009 Samoa Earthquake

AbstractThis study presents tsunami inversion analyses that simultaneously use ocean‐bottom pressure and ocean‐bottom electromagnetic data along with an accurate tsunami propagation model to estimate the earthquake source model for the 2009 Samoa earthquake. This earthquake was a doublet event that occurred along a pair of normal and thrust faults. To the best of our knowledge, this joint inversion of pressure and electromagnetic data is unprecedented. The incorporation of electromagnetic data in the tsunami inversion analysis was relatively simple, and the inclusion of frequency dispersion, self‐attraction, and loading effects in the tsunami propagation calculations allowed the use of tsunami waveforms recorded at distant locations, which improved the reliability of the solutions obtained. Our best source model indicated that the east‐west extent of the plate‐boundary slip area was approximately 50 km, which is narrower than that of a previous fault model, and explained both electromagnetic and pressure data from the 2009 Samoa tsunami.

FemtoPro: virtual-reality interactive training simulator of an ultrafast laser laboratory

The huge field of optics and photonics research and development is in constant demand of well-trained experts. However, it is challenging to teach efficiently the setup process of complicated optical experiments due to limited hardware availability and eye-safety concerns, in particular, in the case of femtosecond lasers. We have developed an interactive simulation of an ultrafast laser laboratory (“femtoPro”) for teaching and training, implementing physical models for the calculation and visualization of Gaussian laser beam propagation, ultrashort optical pulses, their modulation by typical optical elements, and linear as well as nonlinear light–matter interaction. This facilitates the setup and simulated measurement procedure, in virtual reality (VR) and at real-time speeds, of various typical optical arrangements and spectroscopy schemes such as telescopes, interferometers, or pulse characterization. femtoPro can be employed to supplement academic teaching in connection with regular courses in optics or spectroscopy, to train future scientists and engineers in the field of (ultrafast) optics in practical skills, to communicate to other researchers how to set up and align a particular experiment, to “test-build” and simulate new designs of optical setups, to simulate ultrafast spectroscopy data, to offer practical exercises to high-school students, and to reach out to the general public.

Fast automated quantitative phase reconstruction in digital holography with unsupervised deep learning

Digital holography can provide quantitative phase images related to the morphology and content of biological samples. To reconstruct an accurate phase image, several processes, such as phase unwrapping, focusing, and calculation of digital reference wave and numerical propagation, are essential. However, this process is time-consuming. We propose a model that performs phase reconstruction in one-step and two-step using an unsupervised image-to-image translation structure. The two-step reconstruction model translates the phase image, which is obtained by performing numerical propagation on the hologram, into an accurate phase image, whereas the one-step reconstruction model directly translates the hologram into an accurate phase image. The proposed model shows similar high-performance reconstruction to the supervised learning model used in many previous studies. However, since supervised learning is trained in strict pairs, many target domain data (accurate phase imagery) is required. Since the proposed model is trained by unsupervised learning, phase reconstruction can be performed with a small amount of target domain data. The proposed method can help to observe the morphology and movement of biological cells in real-time applications.

A microservice regression testing selection approach based on belief propagation

Regression testing is required to assure the quality of each iteration of microservice systems. Test case selection is one of main techniques to optimize regression testing. Existing techniques mainly involve artifacts acquisition, processing and maintenance, thus hard to apply in microservice regression testing since it is difficult to obtain and process required artifacts from multiple development teams, which is normal in cases of microservice systems. This paper proposes a novel approach, namely MRTS-BP, which takes API gateway logs instead of artifacts as inputs. By mining service dependencies from API gateway logs, MRTS-BP analyzes service change impacts based on a propagation calculation, and selects test cases affected by changes based on impact degree values. To evaluate the effectiveness of MRTS-BP, empirical studies based on four real deployed systems are presented. Retest-all strategy and a regression testing selection approach based on control flow graphs called RTS-CFG are compared with MRTS-BP. The results show that, MRTS-BP can significantly reduce both the number of test cases and overall time cost while maintaining the fault detection capability of selected test suite, and that MRTS-BP can save more time cost than RTS-CFG with the similar safety and precision.

Calibration methods and uncertainties estimation of WEST infrared thermography diagnostics

This paper presents the method toward quantifying the global uncertainty on the blackbody temperature measurement from the infrared (IR) diagnostics of WEST. To address this goal, the main functional elements of the IR diagnostics are identified. Then the temperature calibration and calculation principles are presented and analysed to extract the main potential uncertainty contributors, such as the optical transmission coefficients and their stray lights, or the accuracy of temperature references used for calibration. These contributors are individually estimated, or experimentally measured when a supposed effect on the overall uncertainty is identified, like environmental conditions or parasitic radiations. In particular, effects of environmental temperature on the transmission lines and camera is thoroughly studied. All contributions are then aggregated in the uncertainty propagation calculation and results in an overall temperature uncertainty versus the temperature estimation. The uncertainty is in the range of 5–10% for blackbody temperatures above 200 °C, and progressively worsens when temperature decreases.

Wave-based numerical investigation on diffraction correction for a low-height barrier in energy-based sound propagation model for road traffic noise

In energy-based noise propagation prediction methods, such as CNOSSOS-EU in Europe and ASJ RTN-Model in Japan, sound propagation is calculated by using the equation of sound attenuation by the geometrical divergence of the sound power from a sound source and adding various attenuation corrections such as diffraction effect and ground effect. In the ASJ RTN-Model, the insertion loss due to a semi-infinite barrier to a free field is generally used for the diffraction correction for a single barrier, the top of which is regarded as a knife wedge, whereas the diffraction correction for a low-height barrier is different from that for a general single barrier. It is given as the insertion loss due to a low-height barrier to a semi-infinite barrier, the top height of which is at the ground surface level, in a free field: the diffraction correction is zero when the low-height barrier is 0 m high. However, its range of application is not clear. In this paper, the diffraction correction for a low-height barrier is discussed by comparing the results of three-dimensional wave-based numerical analysis and propagation calculations using the ASJ RTN-Model.

Calculation of annual aircraft noise exposure for Geneva and Zurich airports with the next-generation program sonAIR - first results

The next-generation aircraft noise simulation program sonAIR was designed to precisely predict single flights with the scope of investigating and optimizing noise abatement flight procedures. Recently, sonAIR was implemented in a geographic information system (GIS) to make it suitable for noise mapping calculations of entire airport scenarios. In this study, we conducted first calculations of annual aircraft noise exposure with sonAIR for Geneva and Zurich airports, Switzerland, for the year 2017, simulating several 10'000 single flights and accounting for real conditions in great detail (e.g., detailed emission modelling and considering ground cover in the sound propagation calculation). Our calculations proved the ability of sonAIR to do annual aircraft noise calculations with many simulated flights. Comparing the results to those obtained with the best-practice program FLULA2, which is currently used for official aircraft noise calculations in Switzerland, we found that the noise contours differ on average little in areas with legally relevant noise exposure. However, locally larger differences may occur, primary due to varying ground cover and more detailed sound emission modelling. In this contribution, we present the process of sonAIR for annual aircraft noise calculations, show the most important results and discuss implications for future aircraft noise calculations around airports.

Strategic Noise Mapping in France to 2023: Coupling a national database with the open-source model NoiseModelling

The Environmental Noise Directive (END) requires the realization of strategic noise maps, every 5 years, in order to evaluate the noise impact of roads, railways, airports and the main industries on the inhabitants. To achieve round 4 for major roads and major railways, France has decided to create a national database called PlaMADE, which gathers all the necessary input data (traffic, building, population, relief...) in a unique format, a COVADIS GeoStandard. On the basis of these data, and using the open-source noise propagation calculation tool NoiseModelling, all the indicators and maps have been produced for the first time in an automatic way at a national scale. This paper presents the technical and methodological details of the coupling between the PlaMADE database and the NoiseModelling tool.

Comprehensive Study of the Ammonium Sulfamate–Urea Binary System

The physicochemical properties of binary systems are of great importance for the application of the latter. We report on the investigation of an ammonium sulfamate-urea binary system with different component ratios using a combination of experimental (FTIR, XRD, TGA/DSC, and melting point) and theoretical (DFT, QTAIM, ELF, RDG, ADMP, etc.) techniques. It is shown that, at a temperature of 100 °C, the system under study remains thermally and chemically stable for up to 30 min. It was established using X-ray diffraction analysis that the heating time barely affects the X-ray characteristics of the system. Data on the aggregate states in specified temperature ranges were obtained with thermal analysis and determination of the melting point. The structures of the ammonium sulfamate-urea system with different component ratios were optimized within the density functional theory. The atom-centered density matrix propagation calculation of the ammonium sulfamate-urea system with different component ratios was performed at temperatures of 100, 300, and 500 K. Regardless of the component ratio, a regular increase in the potential energy variation (curve amplitude) with an increase in temperature from 100 to 500 K was found.

An Analytical Framework for Error Propagation Effects in Multiprocess Manufacturing

Analysis of multisource errors accompanying process execution and study of the propagation effects of the corresponding multiprocess manufacturing process are the basic prerequisites for optimizing the generation process and improving the quality of the product. This paper proposes an analytical framework for error propagation effects in multiprocess manufacturing, which completely covers error source analysis, mathematical calculation of error propagation accumulation, and description of error propagation effects, which can provide better support for error traceability, error propagation monitoring, and error dissipation in manufacturing production. First of all, establish the process state model into the features of the manufacturing level, analyze the type of multisource error, and its mode of action when executing the process operation; second, establish the mathematical calculation model of error propagation accumulation based on state space equation is established, so as to realize calculation and analysis of error propagation; and finally, establish the link graph and link matrix of error propagation influence in multiprocess manufacturing process are established to further reveal the scope and path of error propagation influence. In this section of the case study, a plate cover part had been taken as an example, the multisource error in its manufacturing was analyzed, and the propagation and accumulation of these error values are obtained by state space and state transition theory. On this basis, the link graph and its corresponding link matrix were used to explicitly describe the error propagation effects during the multiprocess manufacturing of the example part. The example analysis illustrated the proposed error analysis framework could analyze and calculate the multisource error of multiprocess manufacturing and visually describe the error propagation effects, which showed the effectiveness and feasibility of the proposed method framework.

Integrated Calculation of Acoustic Radiation and Propagation of Underwater Elastic Structures Based on the Simple Source Boundary Integral Equation

Integrated Calculation of Acoustic Radiation and Propagation of Underwater Elastic Structures Based on the Simple Source Boundary Integral Equation

The Floquet–Magnus and Fer Expansions: Application to Control the Spin Dynamics During the Phase Modulated Lee–Goldburg Radiation in Solid-State NMR

Floquet–Magnus and Fer expansion (FE) schemes are used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators. This work focuses on applying the Floquet–Magnus and FE approaches to control the spin system evolution during the phase modulate Lee–Goldburg radiation experiment. Until now, the Frequency switched Lee–Goldburg and its variant called the Phase module Lee–Goldburg have been treated by only the average Hamiltonian theory and the bimodal Floquet approach. In this paper, we use the two developing expansion schemes in solid-state NMR for the calculation of the effective Hamiltonian and propagator during the spin dynamics. Our work unifies and generalizes existing results of the Floquet–Magnus and FEs and delivers illustrations of novel springs that boost previous applications that are based on the classical information. The generality of this work points to potential applications in problems related to solid-state NMR and theoretical developments of spectroscopy as well as interdisciplinary research areas whenever they include spin dynamics concepts.

Fatigue Crack Propagation Study of Bridge Steel Q345qD Based on XFEM Considering the Influence of the Stress Ratio

In the past, fatigue cracks have appeared in the orthotropic steel decks of bridges shortly after they opened to traffic. Previous studies have shown that high tensile welding residual stress exists in welded joints of steel bridges, which significantly changes the average stress and stress ratio of the joints. However, traditional fatigue crack propagation (FCP) calculations based on the Paris equation do not consider the influence of the stress ratio. Steel Q345qD is a common material used in bridges. Therefore, it is meaningful to study the influence of the stress ratio on the FCP life of steel Q345qD. In this paper, an FCP equation based on the energy release rate considering the influence of the stress ratio is first derived and named the da/dN-ΔG-R equation. Next, three material parameters in the equation are determined based on the results from tests of steel Q345qD under different stress ratios. Then, a user subroutine based on the extended finite element method (XFEM) that considers the influence of the stress ratio is defined and the effects of mesh size are analyzed. Finally, the effects of the stress ratio on FCP are discussed and the adaptability of the da/dN-ΔG-R equation is verified by comparing the values obtained from the equation with experimental results. The results show that: with a 95% guarantee rate, three material parameters in the da/dN-ΔG-R equation are: log(C) = −10.71, m = 2.780, and γ = 0.957; in the numerical simulation, a mesh size of 1 mm is more appropriate than other mesh sizes as it shows better accuracy and efficiency; under the same energy release rate range, the crack growth rate decreases as the stress ratio increases; under the same loading amplitude and cycles, the fatigue life decreases as the stress ratio increases; and finally, the numerical results considering the influence of stress ratio based on the da/dN-ΔG-R equation are close to the test results, while the results without considering the stress ratio based on the Paris equation are inaccurate.

Transparent Ho,Yb:YAG crystal waveguide inscribed by direct femtosecond laser writing

We report on the dual-line waveguides in Ho,Yb:YAG crystal inscribed by femtosecond laser writing. The efficient single-mode guidance is demonstrated in the type II waveguide structures at 632.8 nm. The confocal micro-Raman spectroscopy is utilized to characterize both the lattice-damaged tracks and strain-affected regions. Contributions of the refractive index changes from the two main lattice changes are further discussed in combination with beam propagation calculations. The micro-luminescence has been studied, demonstrating that the fluorescence of Ho3+ and Yb3+ ions is well preserved in Ho,Yb:YAG waveguide.

Sensitivity Analysis of the Nasgro Equation Based on the PZL-130 TC-II Orlik Trainer Aircraft Full Scale Fatigue Test

Abstract The study investigates the sensitivity of numerical crack propagation estimations based on the Nasgro equation. The equation is widely used for crack propagation calculations since it considers the whole range of crack propagation speed from threshold to critical values of stress intensity factor range (ΔK). The presented investigation is based on the actual results of the full scale fatigue test (FSFT) of the PZL-130 ‘Orlik’ TC-II aircraft. We provide a brief description of the test and the general approach followed in crack propagation estimations originally carried out after the test. The obtained results are verified in terms of variation of the input data. Overall results are compared and discussed.