Stages Of Failure Research Articles

Research on an Intelligent Perception Data Collection Method

Abstract This article proposes a sensor anomaly event intelligent perception monitoring technology to address the problem of insufficient intelligent perception of landslides. This method achieves real-time dynamic monitoring of abnormal deformation in landslide disasters from deformation, accelerated deformation to instability and failure stages. This article proposes an algorithm that triggers acquisition by sensing abnormal deformation and adjusts the acquisition frequency autonomously. By embedding the algorithm into the monitoring system, real-time monitoring of abnormal event data of disaster bodies can be achieved. The system achieves low-power sleep monitoring mode by adjusting the working mode. This method provides a good real-time understanding of the dynamic evolution laws of landslide bodies and improves the effectiveness of disaster prevention and reduction.

A randomized controlled clinical trial on multimodal prehabilitation in colorectal cancer patients to improve functional capacity: preliminary results.

Major colorectal surgery is associated with 20 to 40% reduction in physiological and functional capacity and higher level of fatigue 6 to 8weeks after surgery. The primary aim of this study was to analyse the effects of a multimodal prehabilitation program in colorectal cancer patients to improve functional capacity. The secondary outcome was to evaluate postoperative complications and length of postoperative hospital stay as well as to determine the costs of implementation and indirect costs. A single centre, single-blind, randomized controlled trial was conducted. Patients of age > 18years undergoing elective colorectal resection for colonic cancer were eligible. Exclusion criteria were metastatic disease, severe walking impairments, renal failure stage > 2, ASA score > 3, preoperative chemo-radiation therapy. Patients have been randomized either to prehabilitation intervention groups, receiving 4-week trimodal prehabilitation (physical exercise and nutritional and psychological support) or to control receiving no prehabilitation. Both groups followed enhanced recovery programs and received rehabilitation accordingly. The primary outcome for functional capacity was measured by the 6-Minute Walking Test (6MWT) 4 and 8weeks after surgery; to evaluate post-operative complications the Clavien-Dindo classification was used. An interim analysis of 71 patients undergoing colorectal surgery was performed, with 35 assigned to interventional arm and 36 to control arm. Baseline characteristics were comparable in both groups. The prehabilitation group showed a significant increase in mean 6MWT distance pre-operatively compared to the control group, with an increase of 96m (523 ± 24.6 vs. 427 ± 25.3, p = 0.01). At 4 and 8weeks, the prehabilitation group maintained significant improvements, with an increase of 103m (514 ± 89 vs. 411 ± 115, p = 0.003) and 90m (531 ± 82 vs. 441 ± 107, p = 0.008), respectively. There were no statistical significant differences in post-operative complications and hospital length of stay between the two groups. The preliminary results of this study indicate that it is feasible to implement a prehabilitation protocol lasting approximately 4weeks. This protocol appears to yield a significant improvement in the physical performance of patients with colon cancer undergoing elective colorectal resection at 4 and 8weeks after surgery.

The Role of Biochemistry in Understanding Kidney Stone Formation andUrinary Health

Renal illness caused by stones is the term for a solid substance concretion that usually develops inside the kidneys. A rising urological condition influences the well-being of people and affects about 12% of the world's population. An increased chance of ending stage of renal failure and they are closely related. There are several types of kidney stones. The CaC2O4 kidney calculi are the most common type. It appears at Randall plaque's renal papillary surfaces. (1) Several physicochemical mechanisms, such as supersaturating, urinary stone nucleation, growth, aggregation, and retention components found in tubular cells, which aid in the complex process of formation of stones. An inequity between the elements that promote or inhibit the crystallization of urine influences these phases. Moreover, Scientists have noticed that renal injury of cells promotes particle retention reticular body. (2)

Features of the course of menopause in women under chronic stress: An observational cohort study

Background. Functional processes in the female organism at the stage of reproductive function failure in menopause attract considerable interest of researchers. The paper presents a study of great medical, biological and social importance into reproductive function failure in women living in the territories with permanent military operations for a long time and, thus, suffering from post-traumatic syndrome, which significantly affects the character of menopause. Objectives. To identify the features of menopausal syndrome in women who have been living under chronic stress (6–8 years) in the zone of ongoing military operations, namely in the Donetsk and Luhansk People’s Republics, and in women from Rostov Oblast — the region free from active military operations.Methods. An observational cohort study involved 60 women (refugees), long-term residents of the territories with ongoing military operations and 60 long-term residents of the territories without military operations, aged 50–65 years, with clinical manifestations of menopausal syndrome; all women were patients of the Research Institute of Obstetrics and Pediatrics, Rostov State Medical University. In accordance with the Stages of Reproductive Aging Workshop (STRAW+10) classification and clinical manifestations of menopause, two clinical groups (n = 30) were formed from the representatives of each region of residence. Group I included 30 women, aged 50–55, from the Donetsk and Luhansk People’s Republics, who had late menopausal transition (stage -1 of STRAW+10) and menopausal syndrome. Group II involved 30 postmenopausal patients (stages +1 and +2 of STRAW+10), aged 60–65, with menopausal syndrome. Group 1 enrolled 30 residents of Rostov Oblast, aged 50–55, who had late menopausal transition (stage -1 of STRAW+10) and menopausal syndrome, group 2 included 30 postmenopausal patients (stages +1 and +2 of STRAW+10), aged 60–65, with menopausal syndrome. Modified menopausal index was considered as the main indicator of the study. Statistical data processing was carried out by means of Statistica 10.01 (StatSoft, USA), Microsoft Excel 2010 (Microsoft, USA), IBM SPSS 24.0 (IBM, USA), and MedCalc (MedCalc Software, Belgium).Results. Long-term female residents of the territories with ongoing military operations were reported to develop menopausal syndrome more often. Rostov Oblast female residents in the late menopausal transition revealed a statistically significant prevalence of a mild degree of menopausal syndrome in 63.3 % of cases compared to 36.7 % of a similar severity of menopausal syndrome in residents of the Donetsk and Luhansk People’s Republics. Meanwhile, women from the Donetsk and Luhansk People’s Republics were indicated with moderate menopausal syndrome in 50.0 % of cases in late menopausal transition and severe syndrome in 33.3 % in postmenopause versus 23.4 % and 10 % of women from Rostov Oblast, respectively. The intensity of neurovegetative and psycho-emotional disorders in women of both regions increases with the aging process of the reproductive system and appears most pronounced in the postmenopausal period.Conclusion. Residents of the Donetsk and Luhansk People’s Republics, who live in the war zone and are exposed to constant threat to life, develop post-traumatic syndrome which significantly intensifies and modulates the already existing functional and hormonal restructuring in the brain subsystems during perimenopause. Non-uniform functional shifts at different levels of the central nervous system under conditions of chronic stress lead to a significant change in intracerebral processes and to an increase in the occurrence and severity of various dysfunctional deviations.

Fatigue damage evolution behaviors and fractional fatigue mechanical model of monzogabbro under true triaxial disturbance test

The disturbance wave caused by excavation or blasting of underground surrounding rock causes fatigue degradation effect of rock and eventually leads to disasters. However, the fatigue damage characteristics and fatigue models of rock under true triaxial disturbance are scare. Therefore, a series of true triaxial disturbance tests were conducted to investigate the rock fatigue deformation, strength and damage behaviors under different conditions. The evolutions of static damage and fatigue damage are separated and investigated respectively. Fatigue deformation and damage of rock under true triaxial stress undergoes three stages: attenuation, constant velocity and acceleration stage. The crack initiation stress can be as the initial condition of the fatigue deformation; the fatigue critical stress σdc of rock entering the acceleration failure stage was proposed and explored, with increasing frequency, σdc increase slightly and with increasing σ2, σdc increase obviously. Then, a novel fractional fatigue mechanical model considering the fatigue damage and intermediate principal stress effects of rock under true triaxial disturbance was proposed. The theoretical results of the model agree well with the results of the tests. Finally, the sensitivity analysis of stresses and model parameters and the model predictions under other untesting conditions were carried out to improve the understanding and prediction level of fatigue failure in underground engineering.

A Machine Learning-Driven Approach to Uncover the Influencing Factors Resulting in Soil Mass Displacement

For most landslides, several destabilising processes act simultaneously, leading to relative sliding along the soil or rock mass surface over time. A number of machine learning approaches have been proposed recently for accurate relative and cumulative landside displacement prediction, but researchers have limited their studies to only a few indicators of displacement. Determining which influencing factors are the most important in predicting different stages of failure is an ongoing challenge due to the many influencing factors and their inter-relationships. In this study, we take a data-driven approach to explore correlations between various influencing factors triggering slope movement to perform dimensionality reduction, then feature selection and extraction to identify which measured factors have the strongest influence in predicting slope movements via a supervised regression approach. Further, through hierarchical clustering of the aforementioned selected features, we identify distinct types of displacement. By selecting only the most effective measurands, this in turn informs the subset of sensors needed for deployment on slopes prone to failure to predict imminent failures. Visualisation of the important features garnered from correlation analysis and feature selection in relation to displacement show that no one feature can be effectively used in isolation to predict and characterise types of displacement. In particular, analysis of 18 different sensors on the active and heavily instrumented Hollin Hill Landslide Observatory in the north west UK, which is several hundred metres wide and extends two hundred metres downslope, indicates that precipitation, atmospheric pressure and soil moisture should be considered jointly to provide accurate landslide prediction. Additionally, we show that the above features from Random Forest-embedded feature selection and Variational Inflation Factor features (Soil heat flux, Net radiation, Wind Speed and Precipitation) are effective in characterising intermittent and explosive displacement.

Population Pharmacokinetic of Vancomycin Administered by Continuous Infusion in Critically Ill Patients

Introduction: Administration of vancomycin dose by continuous infusion (CI) according to population pharmacokinetic (Pop Pk) models is highly recommended in critically ill patients who exhibit pathophysiological changes. Objective: The objective of this study was to develop and validate a Pop Pk model of vancomycin administered by CI in critically ill patients with normal and impaired renal functions. Methods: The Pop Pk study was performed using a nonparametric approach (Pmetrics*). The influence of covariates (gender, age, weight, height, and creatinine clearance [Cr-Cl]) was tested on the model’s Pk parameters. The performance of the final model was assessed using an external dataset. Results: A one-compartment model (volume of distribution [Vd], elimination from compartment [Ke]) was found to show a good prediction performance. The influence of covariates has shown that age and Cr-Cl affected significantly Vd and Ke, respectively. The distribution of simulated vancomycin clearance (CLv) according to different renal function levels showed a negative correlation between CLv and the severity of the renal impairment. The internal validation of the final model showed that the plot of individual-predicted concentration versus observed concentration resulted in r2 = 0.86 in the final model. The external validation of the final model showed an acceptable predictive performance. Conclusion: We developed a Pop Pk model for vancomycin administered by CI in critically ill patients. A significant impact of Cr-Cl and different stages of renal failure on CLv has been demonstrated. The establishment of an individualized proposal dose based on this model may be helpful to achieve the target range which is critical in optimizing the efficacy and safety of this antibiotic.

Experimental study on dilatancy behavior of soft rock under dynamic loading

Correct understanding of rock dilatation plays a non-negligible role in the safety of rock engineering and the efficiency of geological resources extraction. Although the significance of dilatation under quasi-static loading or unloading conditions is well-studied, its behavior under dynamic loads remains poorly understood. This is largely because conventional dynamic testing system fails to capture the volumetric strain evolution of rock under confinement. This study develops a transparent confining chamber in SHPB system with which high-speed 3D-DIC is capable of measuring both axial and circumferential strain history of dynamically compressed rock. The progressive failure stages and volumetric change of red sandstone under confining pressure of 3.5 MPa and strain rates of 129∼292 s−1 were studied and compared with those in quasi-static case. Results show that, the normalized stress thresholds of crack initiation and dilatancy in dynamic cases are much smaller than those in the quasi-static one. The volumetric variation of soft rock is characterized by four distinct stages: elastic contraction, pre-peak dilatancy, strain-softening dilatancy and strain-recovery dilatancy. The pre-peak elastic contraction is negligible compared to the post-peak dilation, and the ultimate dilation observed in dynamic compression is significantly greater than that in quasi-static compression. Increasing strain rate delays the onset of dilatancy, decreases the dilatant rate but remarkably extends the strain-softening dilatant process which is dominant in total dilation. A rate-dependent piecewise model incorporating key strain thresholds and a dilatancy rate factor was established to characterize the dynamic dilatancy behavior. The research results provide a new insight and possible method in dilation prediction for underground engineering subjected to dynamic loading.

Does double pre-notches have a greater impact than single pre-notch on the mechanical and fracture behavior of rock? Insights from three-point bending tests using the numerical approach of grain-based model

The mechanical performance of rock masses is significantly impacted by the existence of cracks. Distribution of the cracks may result in different mechanical or fracture behaviors of rock. To gain a preliminary understanding of such problems, a series of numerical tests of three-point bending (TPB) are designed and carried out with the consideration of single pre-notch and double pre-notches. The numerical method of grain-based model (GBM) approach is employed in this paper, with a validation implemented by comparing the results with previous experiments to demonstrate the reliability of this model. Afterward, a comprehensive investigation, including the mechanical behavior, strength characteristics, crack evolution and progressive failure mechanism of the above mentioned TPB tests are conducted. The conclusions are as follows: (1) During TPB tests, as the offset distance increases, the fracture mode of the single pre-notched specimens gradually transitions from Mode I to Mode II, with the peak fracture toughness occurring at a mixed Mode I-II fracture condition (2p/s = 0.4). Moreover, the failure angle, notch open degree and expansion area all tend to rise regardless of specimens of single or double pre-notches. (2) A thorough exploration of crack evolution shows that the specimens primarily fracture during the crack propagation and failure stages. Shear failure predominates among these stages, with microcracks mostly occurring inside the rock mineral grains. (3) When offset distance increases to a certain degree (2p/s = 0.8), the fracture of specimen ceases to be governed by the pre-notch; instead, it occurs directly from the middle of the beam specimen. This phenomenon can be attributed to the reduction of stress concentration at the notch tip, as inferred from analysis of the contact force chain. (4) In double pre-notched specimen, microcracks initiate at both pre-notches, but the final failure results from crack propagation at one notch tip. Compared to single pre-notched specimen, the presence of double pre-notches exhibits superior fracture resistance performance.

Experimental study on overtopping failure of concrete face rockfill dam

With the frequent occurrence of natural disasters, the problem of dam failure with low probability and high risk has gradually attracted people's attention. This paper uses flume model tests to systematically analyze the overtopping failure mechanisms of concrete face rockfill dam (CFRD) and identify its failure modes. The tests reveal that the longitudinal erosion of the CFRD breach progress through stages of soil erosion, panel failures, and water flow stabilization. Meanwhile, the cross-section breach process involves the evolution of breach size in rockfill materials, including traceable erosion, lateral broadening, and breach morphology stabilization. The fracture characteristics of the water-blocking panel are primarily evident in the flow-time curve. By analyzing the breach morphology evolution processes in longitudinal and cross sections, the flow-time curve can be subdivided into stages of burst flow formation, breach expansion with flow increase, rapid increase of breach flow discharge due to panel failures, and stabilization of breach flow and size. The primary damage process of the CFRD occurs in a cyclical stage of breach expansion, flow increase, panel failure, and rapid discharge. The rigid face plate and granular body structure contribute to partial dam failure, showing a tendency for gradual expansion of the breach. The longitudinal section illustrates dam failure resulting from panel fracture and rockfill erosion interaction, while downstream slopes exhibit failure due to lateral intrusion of rockfill and cyclic instability. These research results can serve as a reference for constructing a concrete CFRD failure prediction model and conducting disaster risk assessments.

Transformational faulting in Mn2GeO4 from olivine to wadsleyite structure: Implications for physical mechanism of deep-focus earthquakes

High-pressure and temperature deformation experiments interfaced with acoustic emission (AE) monitoring have been conducted to study transformational faulting in Mn2GeO4 olivine, which transforms to the β phase, isostructural to wadsleyite. Metastable Mn2GeO4 olivine exhibits a marked embrittlement behavior at temperatures between 800 and 1100 K, emitting numerous AEs. At each temperature, brittle deformation is characterized by a two-stage process: (1) a “preparation” stage with numerous diffusedly located low-magnitude AEs and large b values (>2), and (2) a failure stage where larger-magnitude AEs form a planar distribution with b values about 1. Microstructure analysis reveals extensive kink band development in olivine grains in the recovered samples. Kink band boundaries (KBBs), with a typical thickness of ∼100 nm, are filled with a nanometric β-Mn2GeO4 “gouge”. A dense array of secondary shear localizations is often present within the kink bands, suggesting significant shear deformation therein. The combined observations suggest that faulting in metastable Mn2GeO4 olivine is a self-similar process, from grain-scale to the sample-scale. Both observed embrittlement behavior and the microstructure of metastable Mn2GeO4 olivine are essentially identical to those in Mg2GeO4 olivine we have reported previously, indicating that the physical mechanism of faulting in metastable olivine is insensitive to the specific crystallographic structure of the high-pressure phase. The low b values (about 1) observed in the faulting process in our experiments are similar to those of deep focus earthquakes in cold subduction zones. Our observed mechanism explains deep focus seismicity in cold metastable mantle wedges, provided that the self-similarity assumption holds to geological scales.

Experimental study and finite element analysis on shear performance of high strength steel reinforced ultra-high performance concrete beam

This paper investigates the shear performance of high strength steel reinforced ultra-high (HSSUHPC). Test were carried out on seven beam specimens with the different parameters of web steel ratio, shear-to-span ratio, and steel fibres content in volume. The failure patterns and load-displacement curves were obtained. The bearing capacity, deformation capacity and strain variation laws of UHPC, steel web, stirrups, tensile longitudinal reinforcement and tensile flange of steel were analyzed. The experimental study established the finite element model of the shear performance of HSSRUHPC beams. The results of finite element fit well with the experimental results. Then parametric analysis was carried out. The results showed two shear failure patterns for the HSSRUHPC beam: shear diagonal compression failure and shear-compression failure. The mechanical process of the HSSRUHPC beam could be divided into four stages: the elastic stage, cracking stage, strengthening stage, and failure stage. There were two peak loads for the load-displacement curves. As the steel ratio of the steel web and yield strength of steel increased, the bearing capacity and deformation capacity of the HSSRUHPC beam increased. The shear-to-span ratio had a significant influence on the failure pattern of HSSRUHPC beam, and with the increase of the shear-to-span ratio, the bearing capacity of the HSSRUHPC beam decreased, but the deformation capacity increased. As fibre content increased, the crack resistance and deformation capacity of the HSSRUHPC beam were improved. With the increasing width ratio between the steel flange and beam, the bearing capacity of HSSRUHPC beam increased, but the change range decreased, so it is suggested that the width ratio between the steel flange and beam should not be larger than 0.6. As the stirrup ratio increased, the bearing capacity of the HSSRUHPC beam increased, but the availability of stirrups decreased, so it is suggested the stirrup ratio should not be over 3 %.

Study on the meso-damage characteristics of RC beam under shear failure based on acoustic emission and numerical analysis

Material meso-scopic damage is the fundamental cause of the degradation of the macroscopic mechanical properties of structures, so it is vital to appraise the meso-damage process of various material components. Acoustic emission (AE) technology as a nondestructive testing method can cover the shortage of traditional test to detect the meso-damage. Therefore, in this study, four-point shear tests were conducted on reinforced concrete (RC) beams and AE signals were collected during tests. Results indicated that the shear failure process of RC beam could be divided into three stages based on the correlation between the cumulative AE energy and load-time. Meanwhile, the finite element model (FEM) was established to intuitively obtain the meso-damage evolution process of RC beam in different failure stages. It was observed that the mortar damage, the ITZ damage, the aggregate damage and the reinforcement plasticity damage occurred inside the RC beam and the meso-damage all showed stage characteristics. Besides, the correlation between AE signals and different meso-damage were established by combining the wavelet packet and the cluster analysis. Based on these analysis, the method of assessing the damage severity of RC beam under shear failure was proposed eventually.

Joint load-bearing behaviors and interface failure mechanism of encased coal samples under uniaxial compression

Concrete-encased coal pillars that serve as an effective support structure in coal mines have attracted increasing attention. This paper aims to explore the coupling bearing behaviors and the properties of interface force transfer between the interior coal and the encasing concrete. Laboratory uniaxial compression experiments were conducted on encased coal samples. Additionally, an interface force formula was derived based on deformation coordination and equilibrium conditions, and a mathematical formula was developed to estimate the load-bearing capacities of both the interior coal and the encased concrete. The research indicates that the stress–strain curve of the concrete-encased coal samples exhibits a distinct “double-peaked” phenomenon, and the load is transferred from the interior coal to the external concrete during the failure process. In the early stages of failure, the interface force enhances the strength of the coal pillar, while the lateral strain of the interior coal column exacerbates the damage to the encasing concrete. Moreover, the force at the concrete-coal interface is proportional to the axial loads and the mechanical properties of both materials. The strength of the coal pillar is significantly enhanced by lateral confinement. This study provides an experimental basis and theoretical analysis support for reducing the disaster of coal pillar instability.

Alcohol consumption and heart failure: a dose-response meta-analysis.

This is a protocol for a Cochrane Review (prototype). The objectives are as follows: Main objective To assess the effects of alcohol consumption on the progression to symptomatic (stage C) heart failure in people at risk for heart failure (stage A) or in people with pre-heart failure (stage B). Secondary objectives To assess the effects of alcohol consumption on progression of left ventricular dysfunction in people with stage A or stage B heart failure. We will assess the effect of alcohol consumption on the development of heart failure with reduced ejection fraction, mildly reduced ejection fraction, and preserved ejection fraction. We also aim to evaluate the effects of alcohol consumption on the development of symptomatic (stage C) heart failure over the short, medium and long term.

Propelling Nurse-Led Structured Intervention to Enhance Self-Care among Patients with Chronic Heart Failure (PROACT-HF): A Cluster Randomized Controlled Trial Study Protocol.

Heart Failure (HF) is a common chronic disease that has a high readmission rate and is associated with worsening symptoms and major financial impacts. Disease management implemented during or after an HF hospitalization has been shown to reduce hospitalization and mortality rates. Particularly for outpatients, it is necessary to provide self-care interventions. Structured nurse-led support such as timely follow-ups, including phone calls, is beneficial for improving self-care assessments. Evidence for nurse-led support has been investigated but is less than conclusive. The aim of this study is to compare the effectiveness of a nurse-led structured intervention for outpatients with chronic HF against the usual medical care in terms of self-care behaviors and occurrence of symptom exacerbation or rehospitalization. This is a cluster-randomized controlled trial. A total of 40 facilities with certified HF nurses will be allocated to two-arm clusters at a 1:1 ratio, randomly to the intervention or usual care arms. A total of 210 participants will be assigned from the hospital. Participants will be adults aged 18 years or older diagnosed with chronic HF who are classified as Stage C according to the ACCF/AHA Heart Failure staging system. In the intervention group, patients will receive structured nursing support. This begins with weekly support, including phone calls, for the first month, then transitions to monthly support thereafter. The aim is to ensure the stability of their living conditions, promote medication adherence, and encourage self-management. In the control group, patients will receive the usual care. Primary outcomes will assess the improvement or continuation of self-care behavior as measured by changes in EHFScBS (European Heart Failure Self-Care Behavior Scale) scores. Secondary outcomes include occurrence of readmission within 30 days, 3 months, 6 months, and 1 year after discharge, duration of home care until readmission, and blood levels of BNP and NT-proBNP.

Axial Compressive Performance of CFRP-Confined Corroded Reinforced Concrete Columns

In saline environments, it is difficult for reinforced concrete structures to meet normal durability requirements, which in turn affects the mechanical properties of the members. In this context, this paper proposes a reinforcement method that involves wrapping corroded reinforced concrete columns with CFRP (carbon fiber reinforced polymer) cloth. By conducting axial compression tests on four specimens, key mechanical performance indicators such as failure mode, ductility, and bearing capacity during the entire stress process of the specimens were analyzed, revealing the failure mechanism of CFRP-confined corroded reinforced concrete columns. A refined finite element model of CFRP-confined corroded reinforced concrete columns was established using ABAQUS software. The influence of key parameters such as the number of CFRP wrapping layers, longitudinal reinforcement corrosion rate, and axial compression ratio on the mechanical properties of the specimens was studied, and the influence of each parameter was determined. Furthermore, a formula for the axial compression bearing capacity of CFRP-confined corroded reinforced concrete columns was proposed. The results indicate that in the presence of corroded steel reinforcement, specimens confined with CFRP undergo substantial lateral constraints during the mid to late stages of loading. This approach effectively alleviates the transverse deformation of the concrete. The specimen demonstrated yield bearing capacities and peak loads of 1441 KN and 1934 KN, respectively, representing a 2.2-fold and 2.5-fold increase compared to the non-reinforced specimen. With the increase in the transverse strain of concrete, CFRP begins to play a restraint role, and a more obvious restraint role in the failure stage of members. It is recommended to apply 1–3 layers of CFRP wrapping for a longitudinal reinforcement corrosion rate of 5%, 3–5 layers for a rate of 10%, and 6–8 layers for an overall corrosion rate of 15%. This paper establishes a theoretical framework for investigating the performance characteristics of such columns and offers technical assistance for practical engineering purposes.

Study on hysteresis performance of corroded CHS T-joints under in-plane bending load

This research aims to examine the hysteresis behavior of corroded circular hollow section (CHS) T-joints when subjected to cyclic bending loading. Quasi-static tests including the coupling of brace axial load and in-plane cyclic moment were conducted on corroded CHS T-joint specimens to analyze the effects of corrosion damage on the hysteresis curve, failure mechanism, carrying capacity, and energy dissipation of the joints. Experimental results indicated the corrosion damage located at the different regions of joints had varying effects on the hysteresis behaviors of CHS T-joints. 1) The brace corrosion degree was more severe than the chord corrosion degree under the same exposure condition, however, the chord corrosion had a more significant influence on reducing the stiffness and ultimate carrying capacity of CHS T-joints. The ultimate capacity of CHS T-joints was found to decline by more than 20 % when the equivalent thickness loss of the chord was about 9.2 %. 2) Compared with chord corrosion, the brace corrosion would relieve the concave deformation and local plastic deformation of the chord so that more plastic cyclic damage concentrated around the intersection line. As a result, the through cracks prematurely occurred from the crown points on both sides, and the energy dissipation of CHS T-joints declined by more than 25 % when the equivalent thickness loss of the brace was about 13 %. The presence of axial loading on the brace not only affects the symmetry of hysteresis curves in CHS T-joints with non-uniform corrosion, but also exacerbates the concave deformation of the chord in chord corroded joints during the failure stage, thereby affecting the shape of hysteresis loops and fracture behavior of CHS T-joints when subjected to in-plane cyclic bending load.

Machine learning-based rapid analysis of the failure progress of thin-film electrodes from electric impedance spectroscopy (EIS) data

Abstract Parylene C is a common substrate and encapsulation material used in implantable microelectrodes. Its reliability and failure are of great significance in the research and application of microelectrodes. In this study, three different failure stages of Parylene C thin-film electrodes were modeled using equivalent circuits, and the electric impedance spectroscopy of the electrodes were rapidly analyzed 9 different machine learning algorithms to identify the failure stages. The results showed that the three equivalent circuit models can represent the dynamics of the three failure stages of the Parylene C thin-film electrodes. The support vector machine (SVM) algorithm achieves more than 93% accuracy in identifying the equivalent circuit models from electric impedance spectroscopy data with an average time of 0.0273s. The SVM algorithm has great potential in fast analysis of electric impedance spectroscopy for the endurability study and application of implantable microelectrodes.

An extraction method for early fault features of rolling bearings based on resonance sparse signal decomposition and non-convex second-order total variation denoising

A primary challenge in the field of fault diagnosis is extracting weak fault characteristics of bearings under large background noise and non-stationary conditions. Due to significant noise interference in the signals of rolling bearings, resonance sparse signal decomposition (RSSD) cannot efficiently extract the transient impact components in the early failure stage and the total variation denoising (TVD) method distorts signal waveforms. In this study, a combined extraction method for early fault features of rolling bearings based on RSSD and non-convex second-order total variation denoising (NCSOTVD) is proposed. Firstly, a non-convex function is introduced to define the regularisation term in the second-order TVD method, and the regularisation parameter and the convexity parameter in the NCSOTVD method are respectively screened using the noise standard deviation and the permutation entropy value to enhance the impact characteristics of signals and induce signal sparsity. The NCSOTVD model is solved using the optimisation-minimisation algorithm, so as to achieve noise reduction and feature enhancement of the vibration signals. Then, the low-resonance components of RSSD are denoised using the NCSOTVD method to highlight periodic pulse signals and extract the fault features of the rolling bearings. The simulation results and experimental data show that the method largely suppresses the noise interference, highlights the fault characteristics and reduces the problems of waveform distortion and poor sparsity of the TVD method in the denoising process.