Mechanical Defects Research Articles

A Transformer and YOLOv5-Integrated Visual Defect Detection Method for Mechanic Parts

The defect detection of mechanical parts is a key link in industrial production, but traditional manual detection methods are inefficient and difficult to meet the needs of modern manufacturing. To overcome this challenge, this paper proposes a mechanical part visual defect detection method based on deep vision sensing technology, which integrates Transformer and YOLOv5 models. First, the YOLOv5 model has improved its ability to extract part features. Subsequently, a new detection model was constructed by combining the pre-trained transformer structure with the improved YOLOv5. To validate the performance of the proposed method, we selected two real datasets for experimentation. First, we evaluated the improvement of key elements in the model and found that the improvement of certain elements can significantly improve the average detection accuracy. Next, we compared the proposed model with several typical detection methods, including SSD, Faster R-CNN and RetinaNet. The experimental results show that under the same dataset and measurement standards, the performance of this scheme is superior to the comparative methods, with higher detection accuracy and faster detection speed. The contribution of this paper lies in proposing an innovative visual defect detection method for mechanical parts, which combines the advantages of Transformer and YOLOv5 to achieve efficient and accurate detection of mechanical part defects. This method not only improves detection efficiency, but also provides strong technical support for quality control in industrial production.

Dysfunctional mechanotransduction regulates the progression of PIK3CA-driven vascular malformations

Somatic activating mutations in PIK3CA are common drivers of vascular and lymphatic malformations. Despite common biophysical signatures of tissues susceptible to lesion formation, including compliant extracellular matrix and low rates of perfusion, lesions vary in clinical presentation from localized cystic dilatation to diffuse and infiltrative vascular dysplasia. The mechanisms driving the differences in disease severity and variability in clinical presentation and the role of the biophysical microenvironment in potentiating progression are poorly understood. Here, we investigate the role of hemodynamic forces and the biophysical microenvironment in the pathophysiology of vascular malformations (VMs), and we identify hemodynamic shear stress and defective endothelial cell mechanotransduction as key regulators of lesion progression. We found that constitutive PI3K activation impaired flow-mediated endothelial cell alignment and barrier function. We show that defective shear stress sensing in PIK3CAE542K endothelial cells is associated with reduced myosin light chain phosphorylation, junctional instability, and defective recruitment of vinculin to cell–cell junctions. Using three dimensional (3D) microfluidic models of the vasculature, we demonstrate that PIK3CAE542K microvessels apply reduced traction forces and are unaffected by flow interruption. We further found that draining transmural flow resulted in increased sprouting and invasion responses in PIK3CAE542K microvessels. Mechanistically, constitutive PI3K activation decreased cellular and nuclear elasticity resulting in defective cellular tensional homeostasis in endothelial cells which may underlie vascular dilation, tissue hyperplasia, and hypersprouting in PIK3CA-driven venous and lymphatic malformations. Together, these results suggest that defective nuclear mechanics, impaired cellular mechanotransduction, and maladaptive hemodynamic responses contribute to the development and progression of PIK3CA-driven vascular malformations.

Effect of Pipe Wall Wear Defects on the Flow Characteristics of Slurry Shield Discharge Pipe

During slurry shield tunneling in hard rock or cobble strata, the discharge pipes suffer serve wear and damage. However, the effect mechanism of pipe wall wear defects on the flow characteristics of two-phase flow is unclear. In this study, a three-dimensional slurry particle model of pipeline transport was established using the coupled computational fluid dynamics–discrete element method (CFD-DEM) considering the pipe wall wear defect, and the typical pipeline forms of straight pipe and 90° elbow pipe were selected as the research targets. The results indicated that the localized wear defect of pipes can lead to increased inhomogeneity in the velocity distribution, generating localized low-flow zones and resulting in a reduced flow rate or stagnancy in parts of the pipe. Meanwhile, the wear defect of the pipe results in local shape changes, so that the fluid flow path through the pipe is no longer smooth, causing more vortex/turbulence and secondary flow, where an increased vortex promotes localized kinetic energy reduction and creates larger pressure losses at the elbow. In addition, for the elbow pipe without wear defect, the pressure drop of the elbow increases quadratically from an increase of 6.5% to an increase of 16.9%, with the maximum wear depth increasing from 4 mm to 19 mm. For the straight pipe without wear defect, the pressure drop of the elbow increases linearly, from an increase of 2.2% to an increase of 10.2% with the maximum wear depth increasing from 4 mm to 19 mm. The paper investigates the potential mechanism of pipe flow characteristics influenced by wear defect and provides practical guidelines for the efficient operation of a slurry shield circulating system.

Mechanism and Structural Defects of Zinc Film Deposited on a Copper Substrate: A Study via Molecular Dynamics Simulations

Epitaxial growth can be used to guide the controllable growth of one metal on the surface of another substrate by matching the interface lattice, thus improving the dendrite tendency of metal growth. The atomic arrangement of the Cu (111) crystal plane of the FCC structure is similar to that of the Zn (0002) crystal plane of the HCP structure, which is theoretically expected to promote the heterogeneous epitaxial nucleation growth of metal zinc under low strain. In this paper, the molecular dynamics method is used to simulate the atomic process of zinc film growth on the Cu (111) surface. It is found that the behavior of zinc-adsorbed atoms on the substrate surface conforms to the epitaxial growth mode. The close-packed structure grown along the (0002) direction of the layered clusters is tiled on the Cu (111) surface, forming a highly ordered low-lattice-mismatch interface. When a large area of layered zinc clusters cover the substrate, the growth mode will change from heteroepitaxial growth to homoepitaxial growth of Zn atoms on the zinc film, forming a lamellar distribution composed of FCC and HCP structure grains. Polycrystalline zinc film with a planar structure with a (0002) surface preferred a crystal plane. The increase in incident energy is helpful in improving the quality of zinc films, while the deposition rate, corresponding to the deposition temperature and electrolyte ion concentration, has no significant effect on the surface morphology and crystal structure of single metal films. In summary, the atomic arrangement of the Cu (111) surface has a strong guiding effect on the atomic ordered arrangement in the zinc film crystal, which is suitable for the epitaxial deposition of the substrate to induce the ordered growth of the Zn (0002) crystal plane.

Mutations in histones dysregulate copper homeostasis leading to defect in Sec61-dependent protein translocation mechanism in Saccharomyces cerevisiae.

The translocation of proteins from the cytoplasm to the endoplasmic reticulum occurs via a conserved Sec61 protein channel. Previously, we reported that mutations in histones cause downregulation of a CUP1 copper metallothionein, and copper exposure inhibits the activity of Sec61. However, the role of epigenetic dysregulation on the activity of channel is not clear. Identification of cellular factors regulating copper metabolism and Sec61 activity is needed as the dysregulation can cause human diseases. In this study, we elucidate the intricate relationship between copper homeostasis and Sec61-mediated protein translocation. Utilizing copper-sensitive yeast histone mutants exhibiting deficiencies in the expression of CUP1, we uncover a copper-specific impairment of the protein translocation process, causing a reduction in the maturation of secretory proteins. Our findings highlight the inhibitory effect of copper on both cotranslational and posttranslational protein translocations. We demonstrate that supplementation with a copper-specific chelator or amino acids such as cysteine, histidine, and reduced glutathione, zinc, and overexpression of CUP1 restores the translocation process and growth. This study, for the first time provides a functional insight on epigenetic and metabolic regulation of copper homeostasis in governing Sec61-dependent protein translocation process and may be useful to understand human disorders of copper metabolism.

Multiscale analysis of CO2 adsorption mechanisms on porous carbon: An investigation into the impact of intrinsic defects and pore size.

Porous carbon adsorption represents a critical component of CCUS technologies, with microporous structures playing an essential role in CO2 capture. The preparation of porous carbon introduces intrinsic defects, making it essential to consider both pore size and these defects for a comprehensive understanding of the CO2 adsorption mechanism. This study investigates the mechanisms of CO2 adsorption influenced by intrinsic defects and pore size using multiscale methods, incorporating experimental validation, Grand Canonical Monte Carlo simulations, and Density Functional Theory simulations. Intrinsic defects increase structural disorder and microporous content in porous carbon by distorting the graphene framework, thereby creating additional spaces for CO2 adsorption. Moreover, atomic charge redistribution induced by intrinsic defects disrupts the balance of van der Waals and electrostatic potentials, generating more active adsorption sites and enhancing the strength of CO2 adsorption. This research aims to clarify the facilitative mechanisms of intrinsic defects and pore size on CO2 adsorption in porous carbons and to provide a theoretical basis for designing efficient carbon-based adsorbents.

Study on the surface quality of 10% vol Mg2Si/Al composites after solution treatment

Purpose To improve the surface quality of Mg2Si/Al composites after solution treatment, the formation mechanism of surface defects under milling machining conditions is investigated to reduce the surface roughness. Design/methodology/approach This paper analyzes the formation mechanism of surface defects on Mg2Si/Al composites under micro-milling conditions by establishing a two-dimensional finite element simulation model. Response surface (Box–Behnken) experiments are designed to establish a prediction model for surface roughness, and an analysis of extreme variance is used to investigate the effects of milling depth (ap), spindle speed (vs) and feed rate (vf) on surface quality. NSGA-II multi-objective optimization algorithm is used to optimize the process parameters by considering surface roughness and milling efficiency. Experiments are also applied to verify the relationship between surface defects and particle damage. The effect of depth of cut on surface defects is also investigated. Findings There are few studies on solid solution treated Mg2Si/Al composites. Solid solution treated Mg2Si/Al composites have excellent material properties without changing the original shape of the material, and they are indispensable and critical materials in the fields of aerospace, energy, electronic information and energy transportation. Originality/value This study elucidates the formation mechanism of surface damage in Mg2Si/Al composites, optimizes reasonable process parameters and provides technical guidance for its milling processing. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2024-0309/

Improving Localization Accuracy of Offline Navigation Algorithms for Intelligent Pipeline Inspection Gauges and In‐Line Inspection Robotic Systems

ABSTRACTIntegrity management of pipeline networks is crucial for preemptive maintenance and preventing accidents. In this study, various methods for improving the localization accuracy of the offline navigation algorithm for an intelligent pipeline inspection gauge (PIG) and in‐line inspection (ILI) robotic system are proposed. The digital mapping algorithm utilizes the extended Kalman filter (EKF) with a Rauch–Tung–Striebel (RTS) smoother. Two ILI tools are introduced—magnetic flux leakage (MFL) PIG, which is a typical intelligent PIG for detecting corrosion defects in pipelines, and a new low‐friction geometry robot (LFGR) for inspecting the mechanical defects in low‐pressure, low‐flow pipelines. The MFL PIG has only three odometers to measure the speed of the PIG along the moving direction. Hence, a compensation method for the measured speed was developed and utilized. In addition, an optimization procedure for the parameters of sensor uncertainty modeling was proposed and validated. These methods increased the localization accuracy of the digital mapping algorithm of the MFL PIG. Specifically, the root mean squared value of the two‐dimensional distance error decreased by 47.73%. The proposed methods were applied to the LFGR equipped with four odometers and a high‐accuracy inertial measurement unit. Moreover, additional sensors and a new algorithm for attitude angle correction of the robot were utilized. The proposed methods were successfully validated using field ILI results. The methods enhance the effectiveness of the integrity management of pipeline systems, thus contributing toward their safe and reliable operation.

Analysis of Problems and Countermeasures in China's Stock Market

As an important part of the global financial system, China's stock market has unique characteristics and challenges, such as high market volatility, information asymmetry, policy risks, and market mechanism defects. This paper aims to analyze these major problems facing the Chinese stock market and propose practical solutions. By studying the challenges of market volatility, information asymmetry, policy risks, insufficient investor education, and imperfect legal framework, this paper proposes countermeasures to improve the stability and efficiency of China's stock market. These countermeasures include improving policy transparency, promoting institutional investor participation, strengthening investor education, improving information disclosure mechanisms, and strengthening market supervision. The results show that by implementing these measures, market volatility can be effectively reduced, information transparency can be improved, market efficiency can be enhanced, and support can be provided for the sustainable development of China's stock market. This study provides valuable insights for policymakers, investors, and scholars to promote the healthy and stable development of China's stock market.

Application of Light-Responsive Nanomaterials in Bone Tissue Engineering.

The application of light-responsive nanomaterials (LRNs) in bone tissue engineering shows broad prospects, especially in promoting bone healing and regeneration. With a deeper understanding of the mechanisms of bone defects and healing disorders, LRNs are receiving increasing attention due to their non-invasive, controllable, and efficient properties. These materials can regulate cellular biological reactions and promote bone cell adhesion, proliferation, and differentiation by absorbing specific wavelengths of light and converting them into physical and chemical signals. In addition, the unique surface morphology and biocompatibility of LRNs enable them to effectively load drugs in bone tissue engineering, achieve precise release, and optimize the bone regeneration process. Through photothermal and photodynamic therapy, these materials also possess antibacterial properties and can play an important role in the repair of infectious bone defects. Although LRNs have shown significant advantages in bone tissue regeneration, a series of challenges still need to be overcome to achieve their widespread and effective clinical applications. This article summarizes the basic principles, classification, and potential applications of LRNs in bone tissue regeneration, aiming to provide reference for future research and clinical applications.

Genetic and iatrogenic defects in peripheral tolerance associated with anti-nephrin antibody-associated minimal change disease

Introduction: Minimal change disease (MCD) is a common cause of nephrotic syndrome in children and adults. Immune dysregulation is a contributor, but the relative roles of individual components of the immune system in MCD pathogenesis remain unclear. Case Presentation: Here, we present two patients with defects in immune tolerance mechanisms that developed MCD associated with anti-nephrin antibodies. The first patient had a pathogenic deletion in FOXP3 leading to reduced regulatory T-cells (Tregs). Serum could not be obtained from this patient during the active phase of MCD to directly establish the presence of anti-nephrin antibodies. However, this patient demonstrated IgG dusting over podocyte cell bodies by immunofluorescence microscopy, as well as colocalization of IgG with nephrin in confocal microscopy. The second patient developed MCD in the context of immune checkpoint inhibitor (ICI) treatment for metastatic carcinoma. Anti-nephrin antibodies were detected in this patient during active disease. The patient’s kidney biopsy also showed evidence of binding of anti-nephrin antibodies within the glomeruli. Conclusion: These cases demonstrate that genetic and iatrogenic mechanisms of breakdown in peripheral tolerance can lead to MCD.

Micro-Defects-Related Low Cycle Fatigue Mechanical Model of the Nuclear-Grade S30408 Stainless Steel.

Continuous and interrupted low cycle fatigue tests were conducted on nuclear-grade S30408 stainless steel under different stress conditions at room temperature. Vickers hardness testing and microstructure characterization were performed on the fatigue samples with different fatigue states. The evolutionary mechanism of the microstructure defects in materials under fatigue cyclic loading was discussed. The traditional Basquin formula was used to predict the fatigue life of these fatigue samples. At the same time, a quantitative mechanical model related to the characteristic micro-defects parameter KAM and the Vickers hardness (Hv) was established for the S30408 stainless steel during the low cycle fatigue damage process, and the prediction accuracy of the Vickers hardness is greater than 90%, which is significant and useful for the fatigue life prediction of the 304 stainless steels used in nuclear systems and the safe operation of the reactors.

Polyacrylamide/sodium alginate-based carbon nanocomposite conductive hydrogels for wearable flexible devices

Nowadays, the application of conductive hydrogels in the field of wearable flexible devices is widely known. However, most hydrogels have some defects in mechanics, stability, and self-recovery, which greatly limit...

The mechanism of bright and dark strip visual defects on side milling surfaces induced by loss-cutting

The mechanism of bright and dark strip visual defects on side milling surfaces induced by loss-cutting

Research on the Collaborative Education of Ideological and Political Theory Courses in Chinese Private Universities

In the context of education in the new era, the development of Chinese private universities has been attracting ever-increasing attention. As the core courses for cultivating students' moral character and values in colleges and universities, the collaborative education efficacy of ideological and political theory courses holds significant sway over the quality of talent cultivation in private universities. This paper endeavors to conduct an in-depth exploration into the current status, challenges, and optimization pathways of the collaborative education of ideological and political theory courses in Chinese private universities. Through comprehensive analysis, it is revealed that there exist a multitude of issues in the collaborative education of ideological and political theory courses in private universities, such as feeble collaborative awareness, sluggish platform construction, and defective institutional mechanisms. In light of these problems, corresponding optimization strategies have been formulated, which encompass enhancing the awareness of collaborative education, constructing diverse collaborative education platforms, and refining the institutional mechanisms of collaborative education, with the anticipation of furnishing valuable references for private universities to elevate the level of collaborative education of ideological and political theory courses.

Perioperative morbidity after primary hiatal hernia repair increases as hernia size increases.

Minimally invasive hiatal hernia (HH) repair is the gold standard for correcting mechanical defects of the crural diaphragm due to its safety and favorable clinical outcomes (i.e., relief of patient symptoms). However, several operative factors, including HH size, may negatively affect the postoperative course. We sought to determine if an increase in HH size was associated with an increased risk of perioperative complications, ICU admission, or hospital readmissions after minimally invasive HH repair. We conducted a retrospective observational cohort study of patients who underwent primary HH repair by an experienced foregut surgeon between September 2016 and July 2023. Four groups were defined based on the percentage of stomach at the thorax determined during surgery (small-HH: <25%, moderate-HH: 25-49%, large-HH: 50-74%, and intrathoracic stomach [ITS]: ≥75%). Covariates were compared between the groups, and logistic regressions were performed to identify factors associated with postoperative morbidity. A total of 391 patients (73.7% female; mean age, 64.4 ± 12.5years) comprised the groups: small-HH (n = 160), moderate-HH (n = 63), large-HH (n = 64), and ITS (n = 104). Patients with ITS were older (p < 0.001), had longer operations (p < 0.001), greater blood loss (p < 0.001), longer hospital stays (p < 0.001), and an increased risk of early postoperative complications (aOR 2.59 [CI95: 1.28-5.25], p = 0.009) and ICU admission (aOR 13.3 [CI95: 3.10-57.06], p < 0.001). An increase in HH size was associated with an increased risk of early postoperative complications, ICU admission, and a trend toward higher 30- and 90-day hospital readmissions, likely due to the progressive nature of the disease.

Effect of Oscillating Amplitude on Microstructure and Mechanical Property of Laser Welding of Dissimilar Stainless Steel

The development of oscillating laser beam welding (OLBW) provides an opportunity to improve the weld formation of dissimilar stainless steels. In this paper, the influence of oscillating amplitude on the weld formation, microstructure, and mechanical properties of dissimilar 430/5Cr15MoV stainless steel was studied. The results showed that the weld morphology became smooth and uniform with an increase in the oscillating amplitude, and there was no obvious defect on the surface. The formation mechanism of weld overflow defects on the weld surface was discussed. The width of the weld metal increased with an increase in oscillation amplitude. The influence of beam oscillation on the microstructure of the weld center was significant, i.e., the proportion of equiaxed grains in the center of the welds increased as the oscillation amplitude increased. The maximum microhardness of the weld was obtained at an amplitude of 1.5 mm. Moreover, the tensile strength of the welds reached 477 MPa, which was comparable to the tensile strength of the 430 stainless steel base material. The fracture modes of all welds were typical ductile fractures, which suggests that the oscillation amplitude had a minor effect on the fracture mechanism of the welds. This study provided a new approach to welding dissimilar stainless steels and offers guidance for the selection of an optimum oscillation amplitude.

Oleanolic Acid Modulates DNA Damage Response to Camptothecin Increasing Cancer Cell Death.

Targeting DNA damage response (DDR) pathways represents one of the principal approaches in cancer therapy. However, defects in DDR mechanisms, exhibited by various tumors, can also promote tumor progression and resistance to therapy, negatively impacting patient survival. Therefore, identifying new molecules from natural extracts could provide a powerful source of novel compounds for cancer treatment strategies. In this context, we investigated the role of oleanolic acid (OA), identified in fermented Aglianico red grape pomace, in modulating the DDR in response to camptothecin (CPT), an inhibitor of topoisomerase I. Specifically, we found that OA can influence the choice of DNA repair pathway upon CPT treatment, shifting the repair process from homologous recombination gene conversion to single-strand annealing. Moreover, our data demonstrate that combining sub-lethal concentrations of OA with CPT enhances the efficacy of topoisomerase I inhibition compared to CPT alone. Overall, these findings highlight a new role for OA in the DDR, leading to a more mutagenic DNA repair pathway and increased sensitivity in the HeLa cancer cell line.

ANÁLISE DA CARACTERIZAÇÃO DE UM ALUMÍNIO RECICLADO ESTUDO DE CASO

The main objective of this study is to carry out a microstructural and mechanical analysis of a cast aluminium alloy, focusing mainly on its mechanical strength and defects, with the aim of optimizing the process, finding the cause of the main defects and proposing improvements in the process to reduce defects. The casting method used was gravity casting, in a fixed metal mold, the analysis methodology was carried out in a microstructural analysis by metallography with the Keller chemical attack; then a Rockwell F hardness analysis was carried out where the average was 54 HRF. The chemical analysis revealed impurities such as iron (Fe) and titanium (Ti), which contribute to the formation of coarse particles of the AlFeSi phase, impairing the mechanical properties of these materials. The aluminum alloy was chosen for this research because it is a versatile alloy whose main characteristic is its low melting point and low viscosity and high heat transfer coefficient, short molding time, and the disadvantage is that it presents, during the process, the formation of hydrogen gas, which can be controlled by the degassing process, and the advantage is that the alloys do not present interactions or reactions, metal - mold, having an excellent finish.

Identification of novel variants of XPA and POLH/XPV genes in xeroderma pigmentosum patients in Vietnam.

Xeroderma pigmentosum (XP) disorder is recognized as a genetic condition inherited by autosomal recessive fashion. XP results from a defective DNA repair mechanism that significantly increases skin cancer risk. Fifteen Vietnamese patients were investigated with typical clinical manifestations of XP. Eight XP genes (XPA to XPG and POLH/XPV) were sequenced using peripheral blood samples. Overall, three novel variants on the XPA and XPV genes were detected in members of two families. One novel missense variant c.388A>G (p.R130G) of XPA was found in three patients with XP group A, two novel variants: c.680G>A (p.C227Y) and c.1652dupC (p.Gln553Profs*8) of XPV in one patient with XP group F/G. Our study contributes to the recognition of new mutations in XP patients which have not been reported in Human Gene Mutation Database (HGMD).