Defect Parameters Research Articles

Applicability of simulation-assisted probability of detection analysis considering multiple signal features to eddy current testing of weld

In this study, a simulation-assisted probability of detection (POD) analysis that considers multiple flaw parameters and signal features is presented, including an evaluation of its applicability to eddy current testing for weld inspection. In the proposed method, both the real and imaginary parts of eddy current signals were considered, unlike conventional methods that only consider signal amplitude. Type 304 stainless steel plates were joined by butt welding, and slits were fabricated on the weld path. The eddy current inspection was conducted using a uniform eddy current probe. Numerical simulations were also performed using the finite element method, with the model imitating the experimental situation. The POD contours were calculated using the proposed method, and they exhibited a reasonable tendency. In addition, the 95% lower confidence intervals of the proposed and conventional PODs were compared and were almost equal with respect to the decision threshold, indicating the applicability of the proposed method.

Inductive Type Impedance of Mo/<i>n</i>-Si Barrier Structures Irradiated with Alpha Particles

In silicon microelectronics, flat metal spirals are formed to create an integrated inductance. However, the maximum specific inductance of such spirals at low frequencies is limited to a value of the order of tens of microhenries per square centimeter. Gyrators, devices based on operational amplifiers with approximately the same specific inductance as spirals, are also used. Despite the fact that such solutions have been introduced into the production of integrated circuits, the task of searching for new elements with high values of specific inductance is relevant. An alternative to coils and gyrators can be the effect of negative differential capacitance (i.e., inductive type impedance), which is observed in barrier structures based on silicon.The purpose of the work is to study the low-frequency impedance of Schottky diodes (Mo/n-Si) containing defects induced by α-particles irradiation and determination of the parameters of these defects by methods of low-frequency impedance spectroscopy and DLTS (Deep Level Transient Spectroscopy).Unpackaged Schottky diodes Mo/n-Si (epitaxial layer of 5.5 μm thickness and resistivity of 1 Ohm∙cm) produced by JSC “Integral” are studied. Inductance measurements were carried out on the as manufactured diodes and on the diodes irradiated with alpha particles (the maximum kinetic energy of an αparticle is 5.147 MeV). The impedance of inductive type of the Schottky diodes at the corresponding DC forward current of 10 µA were measured in the AC frequency range from 20 Hz to 2 MHz. DLTS spectra were used to determine the parameters of radiation-induced defects. It is shown that irradiation of diodes with alpha particles produces three types of radiation-induced defects: A-centers with thermal activation energy of E1 ≈ 190 meV, divacancies with activation energies of E2 ≈ 230 meV and E3 ≈ 410 meV, and Ecenters with activation energy of E4 ≈ 440 meV measured relative to the bottom of c-band of silicon.

A new type of magnetising and magnetic flux leakage inspection system for the non-destructive testing of pit defects on the surface of a steel sheet

A new type of magnetising and magnetic flux leakage (MFL) inspection system is designed, in which an ARM microprocessor-based measuring circuit and a novel magnetising device developed by the authors are combined to detect the magnetic field around a pit defect in a steel sheet. Based on a series of careful detection experiments, the spatial distributions of the three-dimensional (3D) MFL components of some typical artificial defects are described and observation, comparison, feature extraction and analyses are then carried out. The results show that the 3D components of the MFL field produced by the newly proposed magnetising device present some distinctive properties compared to those made by the traditional magnetising device. They involve rich information that exhibits close correlations to the morphology and critical parameters of the pit defects on the near side of the steel sheet, demonstrating the feasibility, effectiveness and reliability of the newly proposed inspection system, as well as laying a good foundation for the testing, evaluation or reconstruction and inversion of the pit defect.

Determination of Defects in Planar CH3NH3PbI3 Perovskite Solar Cells Using a SCAPS-1D Simulation Tool

In this work, electrical simulations of planar CH3NH3PbI3 solar cells using a SCAPS-1D (a Solar Cell Capacitance Simulator) simulation tool were performed to determine the density of defects based on the performance parameters and J-V characteristics of actual experimental planar CH3NH3PbI3 solar cells. Two types of defects (bulk and interface) were introduced into the simulation model. The densities of those defects were found by fitting the J-V characteristics and performance parameters including , , and FF to the experimental data. The methods and results reported in this paper showed a close relationship between the parameters of defects in planar perovskite solar cells.
 
 

Clinical guidelines in the pathology of some pet lizard species

Keeping different species of lizards as pets means the development of artificial environments, terrariums or aquateraria, which offer conditions as close as possible to those in the natural environment, as well as the development of appropriate feeding systems. In the category of pet lizards we include: chameleons, agamids, iguanas, skinks, anoles, lizards or geckos. There are extremely different categories of lizards in terms of environmental and feeding requirements and with a special ecobiology, sometimes characteristic of a single species or of several species within a genus. Maintenance deficiencies are most frequently translated by metabolic disorders, frequently associated with infections or parasites that are not diagnosed in individuals of the same species living in the natural environment. In general, a series of viruses or bacterioses overlaped on an immunodeficient background that appears as a result of improper feeding or defective environmental parameters.

A new evaluation method of dented natural gas pipeline based on ductile damage

Dent is the most common defect on natural gas pipelines, leading to pipe leakage or rupture. Since the dent depth-based failure criterion is unreasonable, this work proposed a new ductile damage-based evaluation method for dented natural gas pipelines. The new method was proposed by finite element analysis combined with Oyane ductile damage criterion. Specifically, a finite element-based model was developed to model the formation process of an unconstrained dent, and its accuracy was verified by comparison with test data. A new parameter called the pipeline defect parameter was defined as the ratio of the dent depth to the pipeline diameter to illustrate the dimensionless of dent depth. Then, two safety indicators based on pipeline defect parameter, i.e., monitoring and repairing thresholds, of dented pipelines were determined considering the dent springback. The parameter effects, i.e., indenter geometries and size, as well as internal pressure, were determined. Finally, the proposed method's adaptability and reasonable were demonstrated by case studies. It is expected to provide a useful method for operating dented natural gas pipelines safely.

Monitoring of Radiation Defects Recovery in MgAl2O4 During Annealing by Optical Spectroscopy

The extraordinary radiation resistance of single crystals and ceramics of magnesium-aluminum spinel to neutron irradiation is known, but the mechanisms that provide it are not yet understood. Irradiation of crystals with fast electrons creates defects partially similar to defects in neutron irradiation. The difference in the destructive effect is the significant level of ionization during electron irradiation. Therefore, to compare the results of irradiation by different sources, it is necessary to determine the parameters of radiation defects. One of them is the conditions of radiation damage recovery. When irradiating the crystals with electrons with an energy of 12.5 MeV to a fluence of 6.8∙1016 eV/cm2, the concentration of defects such as F-centers 2.6∙1016 cm-3 and V-centers 3∙1017 cm-3 was obtained. TSL and optical absorption spectroscopy methods were used to determine the state of radiation defects in crystals during annealing. Since annealing at temperatures above 900 K leads to complete discoloration of all optically active centers, therefore, to determine the effect of annealing at higher temperatures, the crystals after annealing were irradiated with ultraviolet light. At temperatures above 900 K, cationic disorder begins to increase, but annealing at 1010 K for 30 minutes was not enough to completely restore the damage to the crystal lattice created by electron irradiation. This is expected, given the characteristic relaxation time of cation disorder, which reaches 1000 hours at this temperature. However, increasing the annealing temperature to 1050 K, in addition to the recovery of radiation defects, creates a noticeable additional difference in TSL, probably due to the formation of complexes from residual F-centers. However, determining the difference between irradiated and non-irradiated crystals gives a difference in the concentration of F-centers at the level of 1015 cm-3.

Photovoltaics literature survey (no. 182)

Photovoltaics literature survey (no. 182)

Harmonic oscillator problem in the background of a topologically charged Ellis-Bronnikov–type wormhole(a)

In this paper, we study the quantum dynamics of non-relativistic particles in the background of a topological chagred Ellis-Bronnikov–type wormhole space-time. We derived the radial wave equation and obtain the eigenvalue solution through the confluent Heun equation. Afterwards, we study the harmonic oscillator problem in the same wormhole background and solve the wave equation using the same technique. In both cases, the ground state energy level E 1,l and the wave function are presented. Finally, we analyze the results and show that the eigenvalue solutions are influenced by the topological defect parameter α and the wormhole throat radius and get them modified.

A dynamic model for simulating vibration response of ball bearings with extended outer race defects for precise spall size estimation

A dynamic model for a ball bearing with an extended outer race defect has been proposed in this paper with an aim of precise fault size estimation. Both the varying stiffness and impact force excitation mechanisms have been incorporated. Besides, the continuously changing contact film damping and, the load zone and the resulting load distribution, are taken into account to accurately obtain the vibration response curve. The impulse force train due to impacts near the entry and the exit edges are also modelled and studied along with other important dynamic characteristics of the rotor bearing system under different operating conditions and defect parameters. The effects of different defect depth and its location, radial load, and shaft speed have been investigated. The theoretical findings were successfully validated using experimental results. The simulated results agree well with the actual vibration response of the defective bearing. Defects of five different sizes were diagnosed in light of the proposed method. A very good resemblance between the actual and the estimated values were achieved with a maximum error of 4.88%, corresponding to the smallest defect.

Modeling of Changes in the Resistivity of Semi Insulating Gallium Phosphide under the Influence of Lighting

The article presents the results of a simulation of changes in gallium phosphide (GaP) resistivity under the influence of lighting. The adopted model of the defect structure is presented along with the defect parameters. Initial conditions created on the basis of a tested material sample, labeled GaP-1, made of monocrystals of semi-insulating gallium phosphide (SI GaP), are presented. The simulation methodology and the created model of the kinetics equations are described. As a result of the simulation, the values of the photocurrent and the electron-hole pair generation coefficient G were assigned to data obtained experimentally depending on the carrier lifetime coefficient τ. Changes in resistivity and concentration of electrons and holes in the bands for gallium phosphide with a structure consisting of five defects are presented. The proposed simulation method can be used to calculate switch-on and -off times and photocurrent values for the semiconductor materials used to construct PCSS (photoconductive semiconductor switches) and other electronic devices.

Recent advances in theab initiotheory of solid-state defect qubits

AbstractSolid-state defects acting as single photon sources and quantum bits are leading contenders in quantum technologies. Despite great efforts, not all the properties and behaviours of the presently known solid-state defect quantum bits are understood. Furthermore, various quantum technologies require novel solutions, thus new solid-state defect quantum bits should be explored to this end. These issues call to developab initiomethods which accurately yield the key parameters of solid-state defect quantum bits and vastly accelerate the identification of novel ones for a target quantum technology application. In this review, we describe recent developments in the field including the calculation of excited states with quantum mechanical forces, treatment of spatially extended wavefunctions in supercell models, methods for temperature-dependent Herzberg–Teller fluorescence spectrum and photo-ionisation thresholds, accurate calculation of magneto-optical parameters of defects consisting of heavy atoms, as well as spin-phonon interaction responsible for temperature dependence of the longitudonal spin relaxationT1time and magneto-optical parameters, and finally the calculation of spin dephasing and spin-echo times. We highlight breakthroughs including the description of effective-mass like excited states of deep defects and understanding the leading microscopic effect in the spin-relaxation of isolated nitrogen-vacancy centre in diamond.

Gas Porosity Defect – What It Means and How to Respond

The foundries are facing problem-related to the selection of the parameter’s value for minimum rejection and maximum productivity. The furan no-bake binders system guaranteed dimensional stability and a comparative good surface finish of the casting. Based on past data in the industry, it is found that gas porosity defect is one of the highest. The phenomenon of the formation of the bubble in the fissures of the mould-metal interface, and later on trapping during the solidification leads to gas porosity. The current research work is focused on the minimization of the defect by the selection of the optimum range of input variables. Based on rigorous literature survey and industrial expert’s opinion, it is found that the parameters like grain fineness number (GFN) of the sand, loss on ignition (LoI) of the used sand, the sand temperature at the mixing time, potential of hydrogen (pH) are important parameters for gas porosity defect in the casting.Design-Expert software and particularly response surface methodology (RSM) and sequential approach using the face-centered central composite design is used for the experiments. The results show that a quadratic model with the removal of some insignificant term is a comparatively best fit for gas porosity defects. After analysis, various favorable levels of different parameters are obtained. The research work is based on realistic problems of the foundries and based on the experimental work. Thus, the provided solution is very much useful for foundries to reduce the rejection, particularly for furan no-bake with furfuryl alcohol as resin and sulphonic acid as catalyst. The research problem addressed in the paper is a genuine problem of the foundries and the sole work is based on experimental evidence.

Research on Comprehensive Evaluation and Early Warning of Transmission Lines' Operation Status Based on Dynamic Cloud Computing.

The current methods for evaluating the operating condition of electricity transmission lines (ETLs) and providing early warning have several problems, such as the low correlation of data, ignoring the influence of seasonal factors, and strong subjectivity. This paper analyses the sensitive factors that influence dynamic key evaluation indices such as grounding resistance, sag, and wire corrosion, establishes the evaluation criteria of the ETL operation state, and proposes five ETL status levels and seven principles for selecting evaluation indices. Nine grade I evaluation indices and twenty-nine grade II evaluation indices, including passageway and meteorological environments, are determined. The cloud model theory is embedded and used to propose a warning technology for the operation state of ETLs based on inspection defect parameters and the cloud model. Combined with the inspection defect parameters of a line in the Baicheng district of Jilin Province and the critical evaluation index data such as grounding resistance, sag, and wire corrosion, which are used to calculate the timeliness of the data, the solid line is evaluated. The research shows that the dynamic evaluation model is correct and that the ETL status evaluation and early warning method have reasonable practicability.

Nonlinear Dynamics of a Microscale Rate Integrating Gyroscope with a Disk Resonator under Parametric Excitation

This article presents an analytical study of the dynamics of a micromechanical integrating gyroscope with a disk resonator. A discrete dynamic model of the resonator is obtained, taking into account the axial anisotropy of its mass and stiffness properties, as well as the action of the electrical control system of oscillations. An analysis of the spectral problem of disk vibrations in the plane is carried out. The nonlinear dynamics of the resonator in the regimes of free and parametrically excited vibrations are investigated. In the mode of parametric oscillations, qualitative dependencies of the gyroscopic drift on the operating voltage, angular velocity and parameters of defects are obtained.

Classification and characterization of coexisting defects from magnetic flux leakage data using deep learning method

Ferromagnetic materials are widely used in infrastructure, such as steam generators, storage tanks, and gas pipelines. During their service time, ferromagnetic materials are subject to deterioration and defects are prone to generate which could damage infrastructures and cause catastrophic accidents. Magnetic flux leakage (MFL) is one of the widely used nondestructive evaluation (NDE) methods to detect and characterize defects in ferromagnetic materials to ensure infrastructure safety. However, many research works have been carried out on the modeling, classification, and characterization of a single defect, while the scenario of coexisting defects is ignored. In practical field, the coexistence of surface and subsurface defects within an overlapping area can cause much earlier than expected deterioration or even penetration, the result of which is more damaging. Here, we propose a convolutional neural network (CNN) based deep learning method to differentiate between single defect and coexisting defects scenarios and estimate the defect sizes including length, width, and depth. Finite-element-method (FEM) simulation models are developed to investigate the effect of coexisting defects on the measured MFL data. The models with different defect parameters are calculated to generate 354 MFL data for the training and testing of deep learning method. The experimental results show that the classification accuracy of deep learning method is over 94% and higher than the traditional machine learning methods, and the defect size estimation errors are within 0.97 mm, 0.59 mm, and 3.67% of wall thickness, respectively, which are validated to be a good classification and characterization tool for the coexisting defects scenario.

Piezocapacitance spectroscopy of a radiation defect in silicon

In this article, using non-stationary capacitive deep-level spectroscopy (DLTS), the dependence of the parameters of the radiation defect with the ionization energy Ei = Ec − (0.33±0.02) eB arising after irradiation with n − Si · λ - quanta of the 60Co isotope and annealing the samples at 250°C on uniaxial compression was studied. It is shown that, under the action of pressure, Ei ΔEi changes depending on the crystallographic direction and reaches values of 0.06−0.12eB. A comparison is made with a similar effect for the level of the A-centre Ec − 0,17 eB.

Comparison of multifractal parameters of surface defects and non-defects

Comparison of multifractal parameters of surface defects and non-defects

ТОКОВИХРЕВОЙ СПОСОБ ВЫЯВЛЕНИЯ ДЕФЕКТОВ МНОГОСЛОЙНЫХ КРУПНОГАБАРИТНЫХ ИЗДЕЛИЙ

Relevance In the process of developing the technology for manufacturing and operating multilayer large-sized objects used in aviation, shipbuilding, railway transport, chemical engineering, automotive and many other industries (for example, multilayer large-sized shells, main pipelines, etc.), there arises the need for operational continuous non-destructive testing of structures large areas to determine the thickness and continuity of the connection of layers with subsequent refinement of the identified defects parameters. Aim of research Development of the theory and means for diagnosing of multilayer large-sized objects technical condition to increase the reliability of their diagnostics results. Research methods To achieve the aim, analytical methods for studying the electromagnetic field, the theory of differential and integral calculus, numerical and computer modeling using software tools were used. Results A mathematical model of the electromagnetic field distribution in the multilayer structure of multilayer large-sized objects, as well as an original control device for multilayer large-sized objects, which allows continuous monitoring of their technical condition, have been developed.

机械损伤对蓖麻种子发芽影响试验及损伤检测研究

To study the types of mechanical damage for castor seeds and their effects on germination, the image processing method was applied to detect the damage affecting germination. Two typical varieties of castor were selected for test. The type of mechanical damage of castor seeds was taken as the factor, the germination rate and germination vigor index were selected as indicators for one-way analysis of variance. The effects of mechanical damage on the germination of castor seeds were analyzed. Different algorithms were applied to extract the features of cracks and seed shell missing, and the corresponding defect parameters were calculated. The results showed that the effects of mechanical damage on the germination rate, germination potential, germination index, and vigor index of castor seeds were significant. The endosperm damage seriously affected the activity of castor seeds and seriously hindered seed germination. According to the analysis of the shell, some castor seeds cracked or there was incomplete shell damage at the same time, the internal endosperm being also damaged. The actual crack length was compared with the length measured by the ultra-depth of field microscope, which found that the margin of error was about 25% and the better error was 10%. Through the morphological processing, it could completely extract the characteristics of castor seed image without seed shells. The error between the extracted feature area and the measured object area function of the super depth of field microscope is about 10%.