Rod Defects Research Articles

Application of DR Detection Technology in Defect Detection of Composite Insulators

The main reasons for the failure of composite insulator are the fracture of core rod and the breakdown of interface, however, due to the particularity of composite insulator, the traditional insulator detection method is not fully applicable to it. The development of composite insulator needs the emergence of new detection technology. In this paper, DR (DirectDigital Radiograph) detection technology is used to detect the artificial simulated defects of composite insulator, and the clear imaging of composite insulator’s core rod defect, core rod and sheath interface defect is obtained. The research results can provide research basis for the application of DR detection technology in the field of composite insulator defect detection.

Elimination of a Retinal Riboflavin Binding Protein Exacerbates Degeneration in a Model of Cone-Rod Dystrophy.

PurposeRiboflavin and its cofactors are essential for cellular energy generation, responses to oxidative stress, and overall homeostasis. Retbindin is a novel retina-specific riboflavin binding protein essential for the maintenance of retinal flavin levels, but its function remains poorly understood. To further elucidate the function of retbindin in retinal health and disease, we evaluated its role in retinal degeneration in a cone-rod dystrophy model associated with the R172W mutation in the photoreceptor tetraspanin Prph2.MethodsWe performed structural, functional, and biochemical characterization of R172W-Prph2 mice with and without retbindin (Rtbdn−/−/Prph2R172W).ResultsRetbindin is significantly upregulated during degeneration in the R172W model, suggesting that retbindin plays a protective role in retinal degenerative diseases. This hypothesis was supported by our findings that R172W mice lacking retbindin (Rtbdn−/−/Prph2R172W) exhibit functional and structural defects in rods and cones that are significantly worse than in controls. Retinal flavin levels were also altered in the Rtbdn−/−/Prph2R172W retina. However, in contrast to the Rtbdn−/− retina which has reduced flavin levels compared to wild-type, Rtbdn−/−/Prph2R172W retinas exhibited elevated levels of riboflavin and the flavin cofactor FMN.ConclusionsThese results indicate that retbindin plays a protective role during retinal degeneration, but that its function is more complex than previously thought, and suggest a possible role for retbindin in protecting the retina from phototoxicity associated with unbound flavins. This study highlights the essential role of precisely regulated homeostatic mechanisms in photoreceptors, and shows that disruption of this metabolic balance can contribute to the degenerative process associated with other cellular defects.

Nonlinear dynamics in the flexible shaft rotating–lifting system of silicon crystal puller using Czochralski method

Silicon crystal puller (SCP) is key equipment in silicon wafer manufacture, which is, in turn, the base material for the most currently used integrated circuit chips. With the development of the techniques, the demand for longer mono-silicon crystal rod with larger diameter is continuously increasing in order to reduce the manufacture time and the price of the wafer. This demand calls for larger SCP with an increasing height, though it causes serious swing phenomenon of the crystal seed. The strong swing of the seed increases the possibility of defects in the mono-silicon rod and the risk of mono-silicon growth failure. The main aim of this paper is to analyze the nonlinear dynamics in flexible shaft rotating–lifting (FSRL) system of the SCP. A mathematical model for the swing motion of the FSRL system is derived. The influence of relevant parameters, such as system damping, excitation amplitude, and rotation speed, on the stability and the responses of the system is analyzed. The stability of the equilibrium, bifurcation, and chaotic motion is demonstrated, which have been observed in practical situations. Melnikov method is used to derive the possible parameter region which leads to chaotic motion. Three routes to chaos are identified in the FSRL system, including period doubling, symmetry-breaking bifurcation, and crisis. The work in this paper analyzes and explains the complex dynamics in FSRL system of the SCP, which will be helpful for the designers in the designing process in order to avoid the swing phenomenon in the SCP.

Overview of Local Rod Defect Detection Studies

This article gives a review of three approaches to solving the problems of detecting local rod and pipeline defects and related problems. In the first approach, local defects are modeled by the matching conditions; in the second approach, by delta functions entering into the differential equation; and in the third approach, longitudinal cavities and cracks are modeled by continuous rod sections with modified stiffness, cross-sectional area, and density. This two-part review describes the works devoted to the detection of defects in distributed mechanical systems using natural frequencies, as well as using transmitted and reflected waves. The second part of the review is devoted to works that use the second and third approaches, i.e., defect modeling by delta functions and continuous rod sections with modified stiffness, cross-sectional area, and density.

Discrete element models of fracture in tooth enamel: Failure mode competition and statistical effects

Capturing how cracks initiate and propagate in tooth enamel is difficult because of the complex three-dimensional microstructure of this material. In this work we use the discrete element method (DEM) to model fracture in idealized enamel structures where the enamel rod microstructure is explicitly represented with DEM elements. The model captures the interactions of a propagating crack with the mineral rods and their interfaces, including crack deflection and penetration into the rods. We used this model to assess the effect of relative strength and stiffness between the rods and the interfaces, of the decussation angle, and of statistical distributions of defects in the mineral rods. We show that higher strength rods (smaller flaws) promote interface crack deflection and branching which increases toughness through spreading of an inelastic region. Stiffer rods increase the load carried by the rod, which ultimately decreases crack resistance. Statistical variations in rod strength were shown to have an overall negative impact on the average crack resistance. In particular, for high coefficients of variation we observed substantial nucleation of ‘daughter’ cracks far from the main crack, which steer the main crack along the weakest trajectories and decrease overall toughness. This model and results provide insights to better interpret fracture experiments in human or bovine enamel, as well as better guidelines for the design of synthetic dental and bioinspired materials.

Automatic Anode Rod Inspection in Aluminum Smelters using Deep-Learning Techniques: A Case Study

Abstract Automatic fault detection using machine learning has become an exciting and promising area of research. This because it accurate and timely way to manage and classify with minimal human effort. In the computer vision community, deep-learning methods have become the most suitable approaches for this task. Anodes are large carbon blocks that are used to conduct electricity during the aluminum reduction process. The most basic function of anode rod inspection is to prevent a situation where the anode rod will not fit into the stub-holes of a new anode. It would be the case for a rod containing either severe toe-in, missing stubs, or a retained thimble on one or more stubs. In this work, to improve the accuracy of shape defect inspection for an anode rod, we use the Fast Region-based Convolutional Network method (Fast R-CNN), model. To train the detection model, we collect an image dataset composed of multi-class of anode rod defects with annotated labels. Our model is trained using a small number of samples, an essential requirement in the industry where the number of available defective samples is limited. It can simultaneously detect multi-class of defects of the anode rod in nearly real-time.

MLEM reconstruction method applied to partial defect verification using simulated data

Gamma emission tomography (GET) using the maximum likelihood-expectation maximization (MLEM) algorithm was developed to detect fuel rods emitting gamma-rays for potential use as a verification tool in nuclear safeguards. To examine the feasibility of the method, scenarios of partial fuel rod defects in a General Electric 7 × 7 boiling water reactor assembly were modeled. Thereafter, ORIGEN-ARP was used to generate the gamma-ray emission spectrum from the fuel, MCNP was used to simulate the measurements using the source term obtained from ORIGEN-ARP. GET was performed using MLEM with passive gamma ray projection profiles provided by MCNP5. As a result, we concluded that GET using MLEM functions is an effective visualization technique of gamma ray emitters for verification. The reconstruction, however, featured minor activities in the center zone of fuel assemblies due to unconsidered attenuation effect, which interferes with the quantitative analysis of rod-wise gamma emitter activities.

Novel molecular mechanisms for Prph2-associated pattern dystrophy.

Mutations in peripherin 2 (PRPH2) have been associated with retinitis pigmentosa (RP) and macular/pattern dystrophies, but the origin of this phenotypic variability is unclear. The majority of Prph2 mutations are located in the large intradiscal loop (D2), a region that contains seven cysteines involved in intra- and intermolecular disulfide bonding and protein folding. A mutation at cysteine 213, which is engaged in an intramolecular disulfide bond, leads to butterfly-shaped pattern dystrophy in humans, in sharp contrast to mutations in the adjacent cysteine at position 214 which result in RP. To help understand this unexpected phenotypic variability, we generated a knockin mouse line carrying the C213Y disease mutation. The mutant Prph2 protein lost the ability to oligomerize with rod outer segment membrane protein 1 (Rom1), but retained the ability to form homotetramers. C213Y heterozygotes had significantly decreased overall Prph2 levels as well as decreased rod and cone function. Critically, supplementation with extra wild-type Prph2 protein elicited improvements in Prph2 protein levels and rod outer segment structure, but not functional rescue in rods or cones. These findings suggest that not all interruptions of D2 loop intramolecular disulfide bonding lead to haploinsufficiency-related RP, but rather that more subtle changes can lead to mutant proteins stable enough to exert gain-of-function defects in rods and cones. This outcome highlights the difficulty in targeting Prph2-associated gain-of-function disease and suggests that elimination of the mutant protein will be a pre-requisite for any curative therapeutic strategy.

Analysis of MFL Model for Sucker Rod Defects and Its MFL Signal Processing

Abstract Magnetic flux leakage (MFL) testing is a nondestructive testing technique widely used in the petroleum industry and pipeline transportation. In this article, the double-coil magnetization method was used to analyze and solve the MFL model of a sucker rod defect, and the collected MFL signals were processed and analyzed. The model of the sucker rod defect was established using the magnetic dipole model, and the leakage magnetic field intensity in the tangential and normal directions above the defect was solved. Then, the influences of the defect width, defect depth, and lift-off value on the leakage magnetic field were obtained. The magnetic field gradients of the MFL signals were deduced and discussed, and the trend of the magnetic field gradients in different directions were obtained. The cubic spline interpolation method (CSIM) was introduced and was applied to the interpolation of MFL data. Finally, the MFL testing platform of the sucker rod defect was constructed, and the collected MFL data were denoised by the wavelet filtering (WF) method; subsequently, the magnetic gradients of the MFL signals were analyzed. The experimental result shows that the continuous MFL signals can be achieved by using the CSIM, and the WF not only maintains the characteristic information of the effective signals but also has a good denoising effect and makes the signals smooth. Simultaneously, the result also indicates that the magnetic field gradients are good tools for analyzing the MFL signals, which reflect the characteristic information of the defect.

Influence of beam butt face nonparallelism on free damped vibration spectrum of the beam

Introduction. The free vibration method is widely applied to detecting internal defects in rod and lamellar structural elements. In this work, it is used to diagnose a rod sample defect consisting in nonparallelism of the rod ends. The possibility of identifying a defect in the form of a bevel of one of the rod butts by the frequency spectrum of free damped longitudinal and transverse vibration after impact actions to the rod side or butt face is considered.
 Materials and methods. An experimental facility and a method of contact-free recording of the frequency spectrum of the rod natural vibration by its acoustic radiation spectrum are presented. Signs of a defect in the form of a split frequency of the rod transverse vibration are detected. At the same time, the maximum amplitudes of the split frequencies correspond to higher or lower frequencies depending on the face to which the impact is applied. This allows not only determining the presence of a defect in the form of the bevelled butt face, but also establishing its orientation relative to the side rod faces.
 Results. An approximate theoretical model is suggested. It explains the effect of frequency splitting in the presence of nonparallelism of the rod butts. For this, the frequency spectra of transverse vibration of two rods with lengths equal to the lengths of the smaller and the larger faces of the original rod with the bevel edge are considered. Experiments show that the differences in the natural frequencies of the bending vibration of these rods, which correspond to the same eigenmodes, are consistent with the differences in the split frequencies of the free damped transverse vibrations of the bevelled-face rod. At this, relationship between the split frequency amplitudes allows determining not only the presence of bevelled face, but also its location.
 Conclusions. The application and development of the method through the analysis of the natural vibration spectrum can lead to creation of remote quality control equipment for rod structural elements.

Online Magnetic Flux Leakage Detection System for Sucker Rod Defects Based on LabVIEW Programming

Aiming at the detection of defects in sucker rod surface, a real-time detection system is designed using the non-destructive testing technology of magnetic flux leakage (MFL). An MFL measurement system contains many components, and this study focuses on the signal acquisition and processing system. First of all, this paper introduces the hardware part of the acquisition system in detail, including the selection and principle of the Hall-effect plural, the design and calculation of the signal conditioning circuit, and the working process of the single chip computer (SCM) control serial port. Based on LabVIEW, a graphical programming software, the software part of the acquisition system is written, including configuration of serial port parameters, identification of detected signals, filtering of original signals, real-time display, storage and playback of data. Finally, an experimental platform for MFL detection is set up, and the MFL measurement is carried out on the transverse and longitudinal defects of the sucker rod surface. The experimental result shows that the designed acquisition and processing system has good detection performance, simple design and high flexibility.

Динамическое взаимодействие потока теплоносителя с тепловыделяющей сборкой

Papers written by Russian researchers on matters concerned with implementing the “Zero Fuel Rod Defect Concept” are reviewed. The results from investigations of structural, technological and operational factors causing loss of fuel rod (FR) leak tightness are considered. The purpose of these studies is to find the root cause affecting the efficiency of a particular fuel assembly (FA) and to make changes for eliminating it. The results of the study aimed at establishing a correlation between the degradation of defective FRs and the fuel operating parameters are presented. The results obtained from testing the models of FRs and FAs for VVER reactors and Kvadrat type FAs for a PWR-900 reactor for fretting-induced wear under the conditions of the PWR reactor water chemistry are analyzed. It is shown that experimental physical modeling of fretting wear for FA fragments with ensuring similarity and possibility of extending the results for the standard FA is an approach based on which fretting wear can be combated. Based on reviewing the results of numerous investigations, conclusions are drawn about the need to refine data on the level of hydrodynamic loads (in particular, when resonances occur) and to refine data on the content of non-condensable gases in the coolant in the operating reactor under different operating conditions. For verifying the design and technological solutions, for substantiating the reliability and operability of new-generation FRs and FAs, for elaborating recommendations on further improvement of the designs and manufacturing technology, and for developing and certifying computer codes, the following must be carried out and used: integrated experimental investigations of the basic regularities pertaining to the dynamic interaction between the coolant flow and fuel, and the changes in the properties and characteristics of fuel for VVER-type reactors; combined application of theoretical and experimental methods for investigating an abnormal growth of the FR and FA vibration levels in order to predict the conditions of their occurrence, and to identify and prevent them. Refinement of these data will make it possible to solve strategic objectives such as increasing the fuel burnup depth, constructing repairable FAs, and substantiating the fuel efficiency in maneuvering modes and under the conditions of increased reactor power.

Effect of partial discharges on the operating condition of high-voltage insulators

The features of the dielectric rod defects and the rod-electrod defects of polymer insulators were investigated by using the developed complex method of contactless remote diagnostics of high-voltage insulators health, which includes the initial detection of local areas with elevated electric field gradients as well as measurement of a set of partial discharges characteristics. The radiation of extra-large partial discharges was detected and partial discharges features were investigated. According to the measurement results, a diagram was constructed for the electro-physical processes that accompany the emission of extra-large partial discharges; and the reasons for their occurrence were established.

Improvement of the technical excellence of multiparameter relay protection by combining the signals of the measuring fault detectors using artificial intelligence methods

The features of the dielectric rod defects and the rod-electrod defects of polymer insulators were investigated by using the developed complex method of contactless remote diagnostics of high-voltage insulators health, which includes the initial detection of local areas with elevated electric field gradients as well as measurement of a set of partial discharges characteristics. The radiation of extra-large partial discharges was detected and partial discharges features were investigated. According to the measurement results, a diagram was constructed for the electro-physical processes that accompany the emission of extra-large partial discharges; and the reasons for their occurrence were established.

Comparative analysis of options for project financing of energy development based on renewable sources

The features of the dielectric rod defects and the rod-electrod defects of polymer insulators were investigated by using the developed complex method of contactless remote diagnostics of high-voltage insulators health, which includes the initial detection of local areas with elevated electric field gradients as well as measurement of a set of partial discharges characteristics. The radiation of extra-large partial discharges was detected and partial discharges features were investigated. According to the measurement results, a diagram was constructed for the electro-physical processes that accompany the emission of extra-large partial discharges; and the reasons for their occurrence were established.

Prph2 initiates outer segment morphogenesis but maturation requires Prph2/Rom1 oligomerization.

The retinal disease gene peripherin 2 (PRPH2) is essential for the formation of photoreceptor outer segments (OSs), where it functions in oligomers with and without its homologue ROM1. However, the precise role of these proteins in OS morphogenesis is not understood. By utilizing a knock-in mouse expressing a chimeric protein comprised of the body of Rom1 and the C-terminus of Prph2 (termed RRCT), we find that the Prph2 C-terminus is necessary and sufficient for the initiation of OSs, while OS maturation requires the body of Prph2 and associated large oligomers. Importantly, dominant-negative physiological and biochemical defects in RRCT heterozygous rods are rescued by removing Rom1, suggesting Rom1 is a regulator for OS formation. Our experiments evaluating Prph2 trafficking show that Rom1 is a key determinant of whether Prph2 complexes utilize conventional versus unconventional (Golgi bypass) secretory pathways to reach the OS. These findings significantly advance our understanding of the molecular underpinnings of OS morphogenesis and particularly the role of Rom1.

Fracture Failure Analysis on Main Wheel Hole of Escalator Step

The escalator steps used in a building fractured during applications. The cause for escalator step fracture has been investigated systemically. The supporting rod main wheel hole of escalator step was studied by means of chemical composition analysis, scanning electron microscope and optical microscope.The results indicate that there are some porosity defects in the support rod of escalator step.The fracture mode of main wheel hole is overload brittle fracture.

Numerical Analysis of Magnetic Flux Leakage of Transverse Defects of Sucker Rod

Abstract Sucker rods are required to operate in a very aggressive environment in the oil well industry. The combined effect of significant mechanical forces and a corrosive environment lead to frequent failures during operation. Furthermore, the detection of the defects of a sucker rod is a difficult, urgent problem to be solved in the oil industry. A solution to this situation would be quite helpful for oil field management as well as in regulating the safety management system of the sucker rod. In this paper, a nondestructive testing model of transverse defect, which is the complex crack of the sucker rod, was established using magnetic flux leakage (MFL) technique and a finite element simulation model for transverse defect was achieved using ANSYS software. Firstly, the model of single-coil magnetization and double-coil magnetization were discussed; the results demonstrated the superior performance of double-coil magnetization in comparison with single-coil magnetization. Secondly, two-dimensional MFL modeling was performed and the influence of magnetization and defect size on MFL testing were analyzed. Finally, a three-dimensional MFL model was proposed, and then the magnetic induction intensity of different liftoff values was analyzed for enhancing the detection reliability. The results showed that the MFL technique can be used to detect transverse defects in a sucker rod.

Radiation-induced defects in strontium carbonate rod for EPR dosimetry applications

The radiation-induced defects in strontium carbonate (SrCO3) rod dosimeter in the dose range of 2.5Gy–25 kGy was investigated using electron paramagnetic resonance (EPR) technique. The EPR spectra of γ-irradiated strontium carbonate (SC) rods exhibit a strong EPR signal with the spectroscopic splitting g-factor 2.008 and a weak signal at g-factor 2.003. This signal increases with increasing irradiation dose. The dose-response function has a good linearity in the low dose range of 2.5–500Gy and slight sub-linearity in the high dose range of 0.5–25 kGy. The dosimeter is nearly humidity independent in the level of 33–77% relative humidity during irradiation. The temperature coefficient of the dose-response function is 0.22% per °C in the temperature range of 20–40°C. The rod dosimeter exhibits a maximum deviation from water equivalency by 7% in the energy range of 0.3–5MeV. The overall uncertainty of dose determination using SC dosimeter is 5.2% and 4.54% (2σ) for low and high dose range, respectively.

The K153Del PRPH2 mutation differentially impacts photoreceptor structure and function.

Peripherin 2 (Prph2) is a photoreceptor tetraspanin, and deletion of codon 153 (K153Δ) leads to retinitis pigmentosa, pattern dystrophy, and fundus flavimaculatus in the same family. To study this variability, we generated a K153Δ-Prph2 knockin mouse. K153Δ-Prph2 cannot form the complexes required for outer segment formation, and in cones cannot interact with its binding partner rod outer segment membrane protein 1. K153Δ causes dominant defects in rod and cone function; however, rod but not cone ultrastructure is improved by the presence of K153Δ-Prph2. Likewise, supplementation of K153Δ heterozygotes with WT-Prph2 results in structural but not functional improvements. These results support the idea that mutations may differentially affect Prph2's role as a structural component, and its role as a functional protein key for organizing membrane domains for cellular signalling. These roles may be different in rods and cones, thus contributing to the phenotypic heterogeneity that characterizes diseases associated with Prph2 mutations.