Failures In Recent Years Research Articles

A differential low frequency eddy current test method for detecting moisture content of high voltage cable water-blocking tape

ABSTRACT The excessive moisture content in the water-blocking tape has been one of the main causes of high voltage cable erosion failures in recent years. However, the 2–4 mm thick aluminium sheath wrapped around the water-blocking tape makes it challenging to detect the moisture content. This study introduces a method for detecting the moisture content of high voltage cable water-blocking tapes based on low-frequency eddy currents. Initially, longitudinal and transverse impedance measurement experiments of the water-blocking tape were conducted to establish the relationship between impedance and moisture content. Since the impedance of the water-blocking tape is significantly higher compared to the aluminium sheath, the eddy current signal was obtained using a differential detection method. An excitation frequency of 10 Hz was chosen to achieve a deeper skin depth. Additionally, an eddy current finite element analysis model was developed, showing that moisture content has an almost linear relationship with the amplitude and phase of the eddy current signal. Finally, an experiment was conducted on an equivalent high voltage cable structure, and the experimental results aligned well with the simulation results.

ON THE ISSUE OF ENSURING THE OPERABILITY OF FREIGHT CAR AXLE BOXES

The article is devoted to analysing the reliability of freight car axle boxes. Wheelsets and axle boxes are especially important for ensuring the traffic safety of trains. The study examined cases of cars uncoupling from a train along the route due to technical faults resulting in delays in train movement. The analysis covered the period of 1995–2023. It found that failures of car axle boxes and automatic brakes predominated. After a significant decrease from 2000–2014, the number of roller axle box failures in recent years fluctuated at 30% of the total number of uncouplings. The analysis obtained a dependency for the change in car detachments due to roller bearing failures, calculated per 1,000 cars in the operating fleet. Despite fluctuations in the number of railcars, the safety level of operations in recent years remained virtually at the same level. The study highlighted that excessive heating accompanies damage in the elements of the axle box unit. It considered methods for detecting possible failures and their advantages and disadvantages. The authors identified the primary causes of axle box component failures. Cylindrical bearings and end mountings remain the most dangerous for failure probability. We demonstrated that the axle box design with cylindrical bearings has a fundamental flaw. Axial forces are perceived through the rolling friction of the ends of the rollers against the ring flanges, leading to the formation of ‘chevron’ scratches and dents on the roller ends, which are stress concentrators. The study established that the surface of the axle box housing is constantly in contact with the side frame of the freight car bogie and wears out. It results in pinching of the axle box body and contributes to the appearance of additional permanent forces acting on the axle box assembly. The end-bearing mounts are weakened and destroyed. Skewed rollers in the bearings cause fatigue failure of the rolling races. It leads to increased heating of the axle box assemblies and uncoupling of the car. A promising direction is the improvement of axle box bodies. Keywords: rolling stock, traffic safety, reliability, axle box assembly, roller bearing, axle box body, failure.

Study on the Evolution Characteristics of Dam Failure Due to Flood Overtopping of Tailings Ponds

There has been a frequent occurrence of tailing dam failures in recent years, leading to severe repercussions. Flood overtopping is an important element contributing to these failures. Nevertheless, there is a scarcity of studies about the evolutionary mechanisms of dam breaches resulting from flood overtopping. In order to fill this knowledge vacuum, this study focused on the evolutionary characteristics and triggering mechanisms of overtopping failures, utilizing the Heshangyu tailings pond as a prototype. The process of overtopping breach evolution was revealed by the conduction of small-scale model testing. A scaled-down replica of the tailings pond was constructed at a ratio of 1:150, and a controlled experiment was conducted to simulate a breach in the dam caused by water overflowing. Based on the results, the following conclusions were drawn: (1) The rise in water level in the pond caused the tailings to become saturated, leading to liquefaction flow and local slope sliding at the initial dam. If the sediment-carrying capacity of the overflowing water exceeded the shear strength of the tailings, water erosion would accelerate landslides on the slope, generating a sand-laden water flow. (2) The breach was primarily influenced by water erosion, which subsequently resulted in both laterally widened and longitudinally deepened breach. As the breach expanded, the sand-carrying capacity of the water flow increased, leading to a faster rate of failure. The breach process of overtopping can be categorized into four distinct stages: gully formation stage, lateral broadening stage of gully, cracks and collapse on the slope surface, and stable stage of collapse. (3) The tailings from the outflow spread downstream in a radial pattern, forming an alluvial fan. Additionally, the depth of the deposited mud first increased and subsequently declined as the distance from the breach grew. The findings of this research provide an important basis for the prevention and control of tailings dam breach disasters due to overtopping.

The Influence of Basalt Aggregate on The Mechanical Performance of Hot Mix Asphalt (HMA) Mixtures

The increasing of traffic load within years reduced the ability to withstand the load path structure, stiffness and strength of the pavement. Along with the development in heavy traffic volume on roads, particularly in tropical locations, the rutting impact has emerged as one of the most significant failures in recent years. A great deal of research has been done to improve the durability and long-term performance of asphalt mixtures in dynamic environments. This paper investigates the effect of basalt aggregate on the improvement of rutting and moisture performance of hot mix asphalt (HMA) mixtures. In this respect, Marshall mix design was employed in the preparation of the specimens. Dynamic creep and moisture susceptibility test have been carried out to evaluate the mechanical properties of the HMA mixture with 30%, 50% and 100% of basalt aggregate replacement. As a result, the performance (creep modulus, permanent deformation and tensile strength) of modified HMA improved remarkably 40- 90% with replacement of 50% basalt aggregate. Based on this studies, the basalt aggregate and its combinations with granite aggregate in asphalt mixes has a significant effect on mechanical properties of HMA mixtures.

Dry Stacking of Filtered Tailings for Large-Scale Production Rates over 100,000 Metric Tons per Day: Envisioning the Sustainable Future of Mine Tailings Storage Facilities

Communities and authorities have been dismayed by globally recorded tailings storage facility (TSF) failures in recent years, which have negatively affected the safety of people and the integrity of the environment. In this context, obtaining the social and environmental license to operate TSFs has become a challenging process for mining companies. This has promoted the trend of using mine tailings dewatering technologies in the mining industry, with dry stacking of filtered mine tailings being recognized worldwide as one of the most acceptable, safe, and environmentally friendly solutions. This article presents a new paradigm in managing mine tailings, with disruptive and futuristic characteristics, considering the dry stacking of filtered mine tailings for large-scale industrial production rates over 100,000 metric tons per day (mtpd). Aspects of filtered tailings management are discussed, such as (i) dewatering process plant with thickening/filtering equipment, (ii) conveyance using fixed and movable conveyor belts, (iii) construction of dry stacking of filtered mine tailings facility, and (iv) implementation of Industry 4.0 technologies for automation of the mining processes. Finally, the article discusses how the large-scale filtered mine tailings solution is applied, considering the advances in the equipment’s performance and implementation of Industry 4.0 technologies as well as the experience gained worldwide in several mining operations. The future global trend is that mining operations with high daily production of mine tailings will apply dry stacking technology without dams to guarantee sustainability, promote continuity of the mining business, ensure the safety of communities, and conserve the environment.

We Need to Do Better: Five Notable Failings in Science Communication

Despite significant growth in interest and investment in science communication, the field has demonstrated some high-profile failures in recent years—exemplified by anti-vaccine and anti-climate change beliefs—supported by interest groups that are often highly effective at promoting anti-science messages. This paper looks at five key areas where science communication research and practice need to do better, and offers some solutions, in order to achieve the impact that science communicators strive for.

Physically based modelling techniques for landslide susceptibility analysis: A comparison

In mountainous areas, landslides are the most common natural catastrophic event, due to these events thousands of people are killed each year, and millions of dollars are lost in property damage. Landslides are mainly induced by earthquakes, rainfall, or manmade activities. Several GIS techniques, such as synthetic aperture radar, ranging data from spaceborne, airborne, and ground-based platforms, optical, and light detection and various physically based models such as SINMAP, TRIGRS, SHALSTAB etc. have been widely used to study slope failures in recent years. Each of these techniques has advantages and limitations for susceptibility analysis of landslides. The current research focuses on landslide susceptibility models that are physically based, their parameterization and working principle. The study infers that TRIGRS is the most commonly used model for slope stability analysis, whereas GEO top model is the only 3D slope stability model which considers the spatial variation of soil parameters hence it can be considered as the most advanced physically based slope stability model.

Feedback thresholds between coastal retreat and landslide activity

Erosive processes have long been considered an important control on landslide activity in coastal environments. Despite its importance and numerous coastal failures in recent years, there has been limited quantitative characterization of the feedbacks between coastal erosion and the commensurate advance of active landslides. Quantitatively understanding the role of erosion as a control on the advance of coastal landslides is imperative from both hazard assessment and geomorphic perspectives, particularly considering future projections of increased erosion from sea level rise. Using a three-dimensional slope stability model coupled with a mass-conserving finite difference analysis, we constrain landslide advance in response to erosion and evolving landslide geometry. We identified an inversely proportional relationship between landslide volume and magnitude of advance for a given level of toe retreat. Landslide aspect ratio and geometry may exert a second-order control on sensitivity of advance to coastal erosion. Further, in comparison to observed landslide advance of three well-characterized landslides in Oregon, the proposed relationships provide insights towards the relative importance of erosion versus other disturbances, such as groundwater rise. Our findings provide insight towards the dynamics of landslides in coastal environments to advance regional coastal landslide hazard and risk assessments.

The Therapeutic Potential of Purinergic Receptors in Alzheimer's Disease and Promising Therapeutic Modulators.

Recent studies have proven that the purinergic signaling pathway plays a key role in neurotransmission and neuromodulation, and is involved in various neurodegenerative diseases and psychiatric disorders. With the characterization of the subtypes of receptors in purinergic signaling, i.e. the P1 (adenosine), P2X (ion channel) and P2Y (G protein-coupled), more attention has been paid to the pathophysiology and therapeutic potential of purinergic signaling in the central nervous system disorders. Alzheimer's disease (AD) is a progressive and deadly neurodegenerative disease that is characterized by memory loss, cognitive impairment and dementia. However, as drug development aimed to prevent or control AD has series of failures in recent years, more researchers have focused on the neuroprotection-related mechanisms such as purinergic signaling in AD patients to find a potential cure. This article reviews the recent discoveries of purinergic signaling in AD, and summarizes the potential agents as modulators for the receptors of purinergic signaling in AD-related research and treatments. Thus, our paper provides an insight into purinergic signaling in the development of anti- AD therapies.

Novel Specific Metallo-β-Lactamase Inhibitor ANT2681 Restores Meropenem Activity to Clinically Effective Levels against NDM-Positive Enterobacterales

ABSTRACTThe global dissemination of metallo-β-lactamase (MBL)-producing carbapenem-resistant Enterobacterales (CRE) is a serious public health concern. Specifically, NDM (New Delhi MBL) has been a major cause of carbapenem therapy failures in recent years, particularly as effective treatments for serine-β-lactamase (SBL)-producing Enterobacterales are now commercially available. Since the NDM gene is carried on promiscuous plasmids encoding multiple additional resistance determinants, a large proportion of NDM-CREs are also resistant to many commonly used antibiotics, resulting in limited and suboptimal treatment options. ANT2681 is a specific, competitive inhibitor of MBLs with potent activity against NDM enzymes, progressing to clinical development in combination with meropenem (MEM). Susceptibility studies have been performed with MEM-ANT2681 against 1,687 MBL-positive Enterobacterales, including 1,108 NDM-CRE. The addition of ANT2681 at 8 μg/ml reduced the MEM MIC50/MIC90 from >32/>32 μg/ml to 0.25/8 μg/ml. Moreover, the combination of 8 μg/ml of both MEM and ANT2681 inhibited 74.9% of the Verona integron-encoded MBL (VIM)-positive and 85.7% of the imipenem hydrolyzing β-lactamase (IMP)-positive Enterobacterales tested. The antibacterial activity of MEM-ANT2681 against NDM-CRE compared very favorably to that of cefiderocol (FDC) and cefepime (FEP)-taniborbactam, which displayed MIC90 values of 8 μg/ml and 32 μg/ml, respectively, whereas aztreonam-avibactam (ATM-AVI) had a MIC90 of 0.5 μg/ml. Particularly striking was the activity of MEM-ANT2681 against NDM-positive Escherichia coli (MIC90 1 μg/ml), in contrast to ATM-AVI (MIC90 4 μg/ml), FDC (MIC90 >32 μg/ml), and FEP-taniborbactam (MIC90 >32 μg/ml), which were less effective due to the high incidence of resistant PBP3-insertion mutants. MEM-ANT2681 offers a potential new therapeutic option to treat serious infections caused by NDM-CRE.

Corporate governance mechanisms and creative accounting practices: the role of accounting regulation

The rising cases of the high profile corporate failures in recent years have been a source of concern to all stakeholders. Thus, the public have become more critical about the effectiveness of corporate governance mechanisms in reducing creative accounting practices. In response to the public outcry, the new legislative initiatives and other reforms were introduced by the various countries. This study investigates the impact of corporate governance mechanisms on creative accounting practices in Nigeria following the enactment of Financial Reporting Council of Nigeria (FRCN) Act 2011. With a sample size of 70 firms, we examine the impact of corporate governance mechanisms on creative accounting before FRCN Act for the periods (2005–2010) and after FRCN Act for the periods (2012–2017). We analysed our data using regression and difference-in-differences estimator. The findings show that the effectiveness of corporate governance mechanisms in reducing creative accounting practices has significantly improved with the enactment of FRCN Act 2011. The study concludes that regulatory intervention contributes to effective corporate governance mechanism which invariably minimizes creative accounting practices. Our finding underscores the role of regulators which is germane in corporate governance activities. The result of this study provides practical implication in the areas of good corporate governance, corporate reporting and accounting regulation. Our work extends prior research on the subject of corporate governance, creative accounting practices and accounting regulation in emerging economies.

Mitigation possibilities of concrete pavement degradation

Monolithic as well as precast Portland Cement Concrete pavement have shown a gradual increase in quantity and severity of defects and failures in recent years. Especially, the radical increase in the auto-destructive deterioration of the concrete structure, which is most often described as the expansion reaction, is alarming. The consequences may lead to extreme reduction of the lifetime of concrete on loaded or unloaded surface courses. The main causes are due to the combined effect of environmental effects (climate, chemical pollution), drainage of roads and the behaviour of the existing cement binders, provided that we do not reflect the modification of pavement structure layers. Only the impact of climate effects can be effectively reduced on the existing roads. The paper presents a summary of results obtained from the current portfolio of secondary concrete protection products. The testing was performed in terms of resistance to water infiltration and durability against the common effects of freeze/thaw and salt. The results show a dependence or independence according to the material basis when exposed to secondary protection products. Oils, silicate emulsions and a group with other material bases, so called other products, behave quite differently.

A Survey on Robust Deadlock Control Policies for Automated Manufacturing Systems With Unreliable Resources

Deadlock is a rather undesirable case in automated manufacturing systems (AMSs). The appearance of deadlock can cause the partial or total stagnation of a system. So far, a large number of deadlock control policies have been developed; nevertheless, the majority are dependent on the assumption that allocated resources cannot break down. In the real world, an AMS consists of a set of concurrent production routes that share and compete for a limited number of resources, such as automated material/component handling devices, buffers, robots, and machines. Resource failures occur unexpectedly. If reasonable control does not exist, a simple resource failure can lead an entire system to stagnation, which can cause enormous economic loss. Therefore, researchers have gradually paid attention to AMSs allowing resource failures in recent years. In this paper, we focus on reviewing and comparing various robust supervisory control policies from the perspective of their structural complexity, behavioral permissiveness, and computational complexity. Some potential future directions are explored. This paper provides a reference source of robust supervisory control of AMSs for researchers and practitioners in this area. Note to Practitioners —In automated manufacturing systems (AMSs), resource failures are common. Their occurrences can lead a system to stagnation, which can cause unnecessary downtime and bring vast economic loss for enterprises. To resolve such stagnation issues, a great number of robust supervisory control policies have been proposed for AMSs with unreliable resources. These policies guarantee that a controlled system can continue to progress without deadlock and blocking states even if some unreliable resources fail to work. By a thorough review of existing robust supervisory control policies for AMSs with unreliable resources, this paper compares and analyzes these policies in terms of their structural complexity, behavioral permissiveness, and computational complexity. The goal of this paper is to provide a reference source in the area to help researchers and practitioners choose a suitable method for solving industrial application problems that are subject to resource failures.

On the External Effects Affecting Torsional Modes in Guide Vanes

Rotor stator interaction in high-head Francis turbines has led to several failures in recent years. Increasing efficiency demands require design optimization of the turbine components, which may lead to thinner profiles. Not only can component not withstand the given loads; quite often one or more of their natural frequencies coincide with that of the rotor-stator interaction. Most of the research published has been on runners, while other parts of the turbine are less studied. Even though guide vanes have torsional modes with frequencies which may be close to the exiting frequency from the rotor stator interaction with the runner, no significant failures due to resonance have been reported. This paper investigates some of the possible mechanisms which may negate resonance in the torsional modes of the guide vanes including; hydrodynamic damping from the flowing water and friction in the guide vane bearings. A case study is conducted on a guide vane where the calculated natural frequency is within 10% of the excitation frequency, while no significant vibrations have been reported. Further, the findings are generalized to Francis turbines of different specific speeds. The results indicate that the dynamics in the bearings are especially important to consider to be able to predict the vibration levels of the guide vane. Having the correct friction factor in the bearing may lead to significant damping and almost eliminate any excitation of torsional eigenmodes.

Excitation of torsional modes in guide vanes

Rotor stator interaction in high-head Francis turbines has led to several failures in recent years. Increasing efficiency demands require design optimization of the turbine components, which may lead to thinner profiles. Not only can component not withstand the given loads; quite often one or more of their natural frequencies coincide with that of the rotor-stator interaction. Most of the research published has been on runners, while other parts of the turbine are less studied. Even though guide vanes have torsional modes with frequencies which may be close to the exiting frequency from the rotor stator interaction with the runner, no significant failures due to resonance have been reported. This paper investigates some of the possible mechanisms which may negate resonance in the torsional modes of the guide vanes including; hydrodynamic damping from the flowing water and friction in the guide vane bearings. A case study is conducted on a guide vane where the calculated natural frequency is within 10% of the excitation frequency, while no significant vibrations have been reported. Further, the findings are generalized to Francis turbines of different specific speeds.

Research on Problem and Corresponding Measures on Reclosing Failure of 220kV Transmission System in Shanxi Grid of China

Reclosing technology is widely used in EHV transmission system of China. In Shanxi 220kV power grid, the reclosing delay time is commonly set to 0.5s, while there used to be several reclosing failures in recent years. This paper focuses on this problem, the transmission system as well as transmission lines are modeled, and factors that may influence secondary arc are investigated. In addition, suggestions on auto-reclosing time setting for Shanxi 220kV power grid are proposed.

Iron ore tailings dry stacking in Pau Branco mine, Brazil

The mining industry has seen several significant dam failures in recent years. Dam failures are associated with errors in design, implementation, operation, and monitoring (Azam, 2014, [2]). Dewatered stockpiling (dry stacking) is a safer alternative to tailings dams (Rico et al., 2008, [3]) for tailings disposal; however, this method has not yet been used in iron ore mines in Brazil, where geotechnical conditions and abundance of water are favorable for the use of tailings dams. This paper describes the results of the study that supported the implementation of an innovative dewatering plant for iron ore tailings in Pau Branco mine, Quadrilatero Ferrifero, Brazil, contributing to improve its sustainability (Gomes et al., 2015, [6]). Magnetic concentration rejects (>45μm) were feasibly dewatered through high-frequency screenings, and slimes (<45μm) were effectively filtered in a horizontal filter press, enabling dry stacking of tailings. A comparison with the current tailings dam structure is presented, demonstrating that Capital Expenditure (CAPEX) for the solution proposed here is significantly lower.

Exploring Group Effects on Individual Ethical Judgements and Whistleblowing Decisions of Accountancy Students

Public confidence in the finance industry has been shaken by the numerous accounting scandals and corporate failures in recent years. These events have damaged the high regard and perceived integrity of professional accountants. As university students are prospective business leaders, it is important to develop their ethical reasoning and judgement to uphold the professionalism and justice in society. In this study, we examine the ethical judgement of final year accountancy students using brief vignettes that describe scenarios such as violations of codes of ethics, involvement in fraudulent activities, and earnings management. The various scenarios are commonly encountered by certified public accountants (CPA). In particular, we used a survey questionnaire to obtain 120 final year accountancy students perceived ethical responses to 6 vignettes together with their whistle blowing responses to each vignette, from inaction to internal or external whistle blowing. After they completed their individual answers, the students were requested to form groups of three to four members to provide group responses to the same set of vignettes. The results of this study provide evidence that prospective CPA can be encouraged to think independently, work collaboratively and enhance their ethical sensitivity and judgement through participating in group discussions. The limitations of the study are identified along with suggestions for future studies.

National Culture and Internal Control Disclosures: A Cross‐country Analysis

AbstractManuscript TypeEmpiricalResearch Question/IssueThis study examines the association between national culture and the amount of information on internal controls listed companies disclose in their annual reports. In particular, we argue that culture affects managers' perceptions of the costs and benefits of disclosing information and, consequently, drive managers' disclosure choices. In addition, we investigate whether culture indirectly, via investor protection, determines disclosure decisions.Research Findings/InsightsUsing unique hand‐collected data from a sample of 4,370 firm‐year observations for 1,559 firms from 29 countries for the period 2005 to 2007, we find that national culture directly affects such disclosures. Moreover, we show that national culture also indirectly affects disclosures via the level of investor protection in a country.Theoretical/Academic ImplicationsThis article is the first to examine cultural determinants of internal control disclosures using a framework in which managers' disclosing decisions are determined by the trade‐off between the costs and benefits of disclosing such information. Moreover, we are the first to demonstrate that culture not only directly but also indirectly, via investor protection, influences disclosure choices.Practitioner/Policy ImplicationsThis study contributes to the debate on the development and design of corporate governance practices. Accounting scandals and corporate failures in recent years have raised calls for improved internal controls, as well as enhanced reporting about these internal controls. Many of these calls are characterized by the view that there is an optimal way of developing such systems. We show that differences in internal control disclosures are influenced by cultural differences. Therefore, introducing a uniform approach to demanding disclosure of information on internal controls may not necessarily translate into uniform reporting practices.

Microstructural analysis of laser micro-welds between copper and aluminum

Currently used ultrasonic welded joints for assembly and packaging of Li-Ion batteries have reliability concerns for automotive applications, as the battery is subjected to vibration and other mechanical loads. The sealing of the battery can is very critical for safety. Due to battery weld failures in recent years, the postal service has put ban on shipping Li-ion batteries via regular mail. A laser based alternative joining technology has the potential to offer robust, fast and cost-effective processing of Li-Ion batteries. Before the technology can be fully implemented, it is imperative to understand the effects of various process parameters on the robustness of the weld. In the present analysis, a preliminary study is performed to understand the effect of laser scanning speed on the micro-structural and physical characteristics of the materials in the weld area that ultimately affect the bond quality. Samples are created by welding aluminum and copper in lap shear configuration using a continuous wave fiber laser. Two sets of samples are created using a laser power of 225 W; however, the scanning speeds are 300 and 400 mm/s. Scanning electron microscopy and energy dispersive spectroscopy are performed in the weld area to understand the microstructural and physical characteristics of the joint that may have been affected by the processing parameters.