Physical Failure Research Articles

STUNTING, PEMERIKSAAN KEHAMILAN DAN KONSUMSI TABLET TAMBAH DARAH IBU HAMIL DI INDONESIA: ANALISIS DATA RISKESDAS 2013

The stunting rate of children under the age of two in Indonesia increased by 3.8% from the year of 2016 to 2018. Stunting in children, besides having an impact on children's growth and development, also results in economic losses because physical growth failure reduces productivity. Cognitive failure causes decreased performance in school, so that increase health care costs. The purpose of the study was to determine the relationship between pregnancy check-ups and the consumption of blood-supplemented tablets (TTD) in pregnant women with stunting ≥ 90 tablets in Indonesia by analyzing the 2013’ Riskesdas data. The final analytical sample was 11,029 aged 0-2 years in all provinces in Indonesia. Statistical analysis was performed with chi-square at a significance level of 5%. Stunting children 0-23 months in Indonesia is 33.3%. Chi-square analysis showed that there was a relationship between standardized antenatal care and consumption of TTD in pregnant women 90 tablets with stunting in children aged 0-23 months (p<0.05). Mothers who do not carry out standardized pregnancy check-ups have a 1.03 times risk of having stunting children compared to mothers who carry out standardized antenatal care. Mothers who took TTD <90 tablets had a 1.05 times chance of having stunting children compared to mothers who took TTD 90 tablets.
 Keywords: Antenatalcare, Children under two years; Stunting; consumption of iron tablets

Millimeter-scale, Large Uniform Area Semiconductor Device Delayering for Physical Failure Analyses and Quality Control

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Failure mechanism of 4H-SiC junction barrier Schottky diodes under harsh thermal cycling stress

The concern in the long-term reliability of the SiC power devies is raised lately in power electronic field due to its brief history and limited data. In this work, discrete 1200 V/20A SiC JBS diodes have been intensively investigated by HTRB, HAST, and TCT. 2 % samples have failed in the harsh thermal cycling test, showing that the failure mechanism is attributed to field-oxide cracking. The electrical and physical failure analysis pointed out that a gradual degradation occurred at the termination structure, causing non-recoverable damages and provoking a significant increase in the leakage current. The FIB cut and SEM analysis showed the delamination existence between field oxide layer and silicon carbide layer in the degraded devices. The observed leakage current after the TCT could be well correlated with the formation of the delamination, which created a current leaking path between active and termination region. These findings emphasize the importance of SiO2/SiC interface quality in the long-term highly reliable SiC power devices, and indicate further optimized design of SiO2 passivation layer or other alternative materials is urgently needed to overcome this structural weakness.

An Interacting Negative Feedback Mechanism in a Coupled Extreme Weather–Humans–Infrastructure System: A Case Study of the 2021 Winter Storm in Texas

Extreme weather has long been a threat to human life and critical infrastructures. Previous studies have focused on the reliability and vulnerability of single or interdependent infrastructures under extreme weather threats. However, knowledge of the interactions between coupled real-world complex systems, especially the cascading failure process induced by external shocks, is essential, but the interactions receive less attention. Here, we took the historical winter storm of Texas that occurred in February 2021 as a case study and collected multisource data to explore the interaction between humans and the power system affected by extreme weather. A connectivity-based network was proposed to analyze the connectivity robustness and simulate the cascade of overload failures under random and malicious attacks. Results showed that this network presents higher robustness under random attacks in terms of network connectivity. However, a highly heterogeneous distribution of load was shown in this network, making it particularly vulnerable to attacks and easier to trigger cascading failures. An interacting negative feedback mechanism was discovered in this coupled extreme weather–humans–infrastructure system. Extreme weather events directly caused physical failure in infrastructures, while their impact on individuals stimulated the power demand for heat. An increase in demand further intensified the load on the power network, which induced functional failure in infrastructure systems and finally aggravated the adverse impact on people as end-users in return. This feedback loop inspired us to reconsider the relationship among natural disasters, critical infrastructure, and humans. Furthermore, even under the background of climate change, the impact of extremely cold weather on electric infrastructures is still worthy of attention since the fluctuation of yearly minimum temperature outstood in eastern Texas, where the majority of the population and electric transmission facilities are located. Thus, it is noteworthy to integrate the interaction between systems in the vulnerability assessment of infrastructure systems or the impact prediction of intense external shocks in future research.

How Small Slip Surfaces Evolve Into Large Submarine Landslides—Insight From 3D Numerical Modeling

AbstractSubmarine landslides are a major marine geohazard affecting resilience of offshore infrastructure and coastal urban centers. Attention has previously been paid to quantifying post‐failure dynamics of catastrophic submarine debris flows and their consequences. However, pre‐failure initiation and growth of a small slip surface evolving into a large submarine landslide are still less understood. This study aims to explore the physical failure mechanism of submarine landslides initiated from small slip surfaces and to quantify key features of failure evolution. They are achieved by modeling the entire three‐dimensional (3D) landslide evolution, integrating the initiation and growth of slip surface, failure of slab above the slip surface, post‐failure mass movement and re‐deposition of transported sediments, using a novel numerical method. The characteristics of the slip surface growth within a favored layer and the patterns of the slab failure in the overlying layer have been thoroughly discussed. The transition from the pre‐failure slip surface growth to the diverse post‐failure mass movement are first observed and discussed with the 3D geometry effects, revealing the complex cascading mass movement mechanisms. The criterion for unstable growth of a planar slip surface and critical condition for slab failure are proposed. The findings from the study facilitate scientific understanding of the evolution of historic events and help safeguarding offshore developments against submarine landslide recurrence.

Safety Impact Analysis Considering Physical Failures and Cyber-Attacks for Mechanically Pumped Loop Systems (MPLs).

As complex systems composed of physical and cyber components, mechanically pumped loop systems (MPLs) are vulnerable to both passive threats (e.g., physical failures) and active threats such as cyber-attacks launched on the network control systems. The impact of the aforementioned two threats on MPL operations is yet unknown, and there is no practical way to evaluate their severity. To assess the severity of the impact of physical failures and cyber-attacks on MPLs, a safety impact analysis framework based on Elman Neural Network (ENN) observers and the Gaussian Mixture Model (GMM) algorithm is suggested. The framework discusses three common attack and failure modes: sensor hard failure that occurs suddenly, sensor soft failure that occurs gradually over time, and denial-of-service (DoS) attacks that prevent communication between the controller and valve. Both sensor failures and DoS attacks render the system unsafe, according to simulation data. In comparison to DoS attacks, however, sensor failures, particularly soft failures, inflict the greatest harm to the MPLs. Furthermore, sensors engaged in global control, rather than those involved in local control, need additional protection.

Phase field mechanics of residually stressed ceramic composites

ABSTRACT A phase field theory for crystalline solids accounting for thermoelasticity, fracture, twinning, and limited slip is presented. Residual stresses are incorporated via referencing thermoelastic strain to a reference state that is not always stress-free. Rate dependence, dissipated energy, and residual strain energy (possibly degraded by local fracture) are included in the theory, with physically valid predictions first verified for homogeneous stress states. A variational form of the model is implemented in finite element (FE) calculations of three-dimensional (3-D) polycrystalline aggregates consisting of up to two different crystal constituents and a binding matrix along grain and phase boundaries. Model specifics correspond to constituents of boron carbide-titanium diboride (BC-TiB) ceramic composites. Effects of thermal-residual stresses incurred during processing, as well as other local microstructure properties and physical features, on deformation and failure mechanisms are revealed. Peak aggregate strengths observed for different boundary conditions demonstrate a pressure-dependent failure surface.

COMPARISON OF FIBER CONCRETE PROPERTIES FOR INDUSTRIAL FLOORS AND ROAD PAVEMENTS WITH STEEL AND POLYPROPYLENE FIBER

The article presents a comparative analysis of the type of dispersed reinforcement effect with steel fiber produced by «Stalkanat-Silur» (50 mm length, ⌀1 mm) and polypropylene fiber «Baumesh» produced by BAUTECH-Ukraine LLC (36 mm length, ⌀0.68 mm) on physical and mechanical properties and failure mode of fiber-reinforced concrete samples for cement concrete pavements and industrial floors. The indicators of strength and durability as one of the most important concrete properties for pavement structures, that are constantly operate under the influence of high dynamic loads were determined. The possibility of using the studied compositions of concrete with structural fiber of different types is analyzed. All concrete mixtures had equal workability S4. For fiber-reinforced concrete mix preparation, Portland cement ПЦ II/А-Ш-500 (CEM II/A-S 42.5 R), crushed stone 5-20 mm and sand with a fineness modulus of 2.75 were used. Polycarboxylate superplasticizer MC-PowerFlow 3200 was used to achieve the required workability of fiber concrete mixtures. It has been established that the use of dispersed reinforcement increases the concrete compressive strength by 13-16%, flexural strength increases by 30-31%, and the abrasion resistance decreases by 31-39%. The use of dispersed reinforcement with «Baumesh» polypropylene fiber in an amount of up to 3 kg/m3 makes it possible to increase the compressive and flexural concrete strength and also to reduce its abrasion resistance on the same scale as the use of dispersed reinforcement with steel anchor fiber «Stalkanat-Silur» up to 25 kg/m3. In this case, from an economic point of view, the use of polypropylene fiber is more appropriate. The optimal content of dispersed reinforcement to increase the strength and abrasion resistance in the fiber-reinforced concrete composition was determined. The fiber-reinforced concrete compositions with steel and polypropylene fibers of compressive strength grade C25/30, and flexural strength grade Btb 3.6, with an increased abrasion resistance were obtained.

Cyber LOPA: An Integrated Approach for the Design of Dependable and Secure Cyber-Physical Systems

Safety risk assessment is an essential process to ensure a dependable cyber-physical system (CPS) design. Traditional risk assessment considers only physical failures. For modern CPSs, failures caused by cyber attacks are on the rise. The focus of latest research effort is on safety–security lifecycle integration and the expansion of modeling formalisms for risk assessment to incorporate security failures. The interaction between safety and security lifecycles and its impact on the overall system design, as well as the reliability loss resulting from ignoring security failures, are some of the overlooked research questions. This article addresses these research questions by presenting a new safety design method named cyber layer of protection analysis (CLOPA) that extends the existing layer of protection analysis (LOPA) framework to include failures caused by cyber attacks. The proposed method provides a rigorous mathematical formulation that expresses quantitatively the tradeoff between designing a highly reliable and a highly secure CPS. We further propose a co-design lifecycle process that integrates the safety and security risk assessment processes. We evaluate the proposed CLOPA approach and the integrated lifecycle on a practical case study of a process reactor controlled by an industrial control testbed and provide a comparison between the proposed CLOPA and current LOPA risk assessment practice.

A novel adaptive boosting algorithm with distance-based weighted least square support vector machine and filter factor for carbon fiber reinforced polymer multi-damage classification

Adaptive boosting (AdaBoost) algorithms fuse multiple weak classifiers to generate a strong classifier by adaptively determining the fusion weights of the weak classifiers. According to incorrect or correct classification results, sample weights become larger or smaller. However, this weight update scheme neglects valuable information in the results. Moreover, an important requirement for weak classifiers is an accuracy higher than random guessing. This requirement is likely to lead to an unexpected result. This means that several generated weak classifiers with similar classification results cannot learn from each other. Consequently, the advantage of fusing multiple weak classifiers disappears. The classification and therefore distinction of different failure modes in materials is a typical task for classical nondestructive testing approaches as well as for new approaches based on machine learning methods. In the case different approaches can be applied, the main question is, which and how tuned approaches provide the best results in terms of accuracy or similar metrics. In the multi-damage classification task distinguishing different physical failure mechanisms in Carbon Fiber Reinforced Polymer (CFRP), the above two aspects complicate the application of AdaBoost algorithms. To improve the results, a novel AdaBoost with distance-based weighted least square support vector machine (WLSSVM) and filter factor is proposed. The distance-based WLSSVM is employed to increase the diversity of weak classifiers, the distances of the classification plane and samples are used to measure the classification task. The filter factor is proposed to filter out unnecessary classifiers contributing less to the final decision. The experimental results demonstrate that the improved AdaBoost schemes with distance-based WLSSVM and filter factor outperform state-of-the-art algorithms. The effects of the scheme using the new weighted update and the filter factor on the algorithm are discussed, respectively. The experimental results show that the combination of the two schemes perform better than other schemes.

Vulnerability analysis of cyber physical systems under the false alarm cyber attacks

More and more infrastructure networks have evolved into cyber physical systems (CPS). Among the previous work, CPS has developed a series of emergency mechanisms to deal with physical failures or attacks. However, the occurrence of cyber attacks, can still severely affect the normal operation of CPS. Thus, the goal of this paper is studying and analyzing the vulnerability of CPS under the cyber attacks. Taking the smart grid as a typical CPS, we consider a specific attack scenario—false alarm attack (FAA), and mathematically propose the FAA model. The attackers can inject hidden vector to make the control center mistakenly believe that links are overloaded, which further results in unnecessary power loss. Based on the FAA model, we further analyze the vulnerability of CPS under different network structures and redundant parameters. Finally, we propose a hybrid indicator, which takes the topological and electrical characteristics of links into consideration, to identify the vulnerable links in smart grid. The simulation results show that the hybrid indicator can effectively identify the vulnerable links, and has a strong correlation with the vulnerability of smart grid. Our work can provide new insights into the construction of robust CPS.

A novel clustering-based method for reliability assessment of cyber-physical microgrids considering cyber interdependencies and information transmission errors

In recent years, the evolution of microgrids (MGs) toward a complex interacted cyber-physical system is significant, which has received much attention. Cyber-physical MGs (CPMGs) are vulnerable to various cyber-physical interdependencies mainly. Therefore, the reliability evaluation of such systems is a crucial issue. Several research works have focused on the reliability assessment of CPMGs in the literature. However, there is a research gap in developing fast and accurate models to assess the reliability of CPMGs, simultaneously considering cyber and physical failures, cyber-power interdependencies, and information transmission errors. This article aims to fill such a knowledge gap by developing a new clustering-based method to evaluate the reliability of CPMGs. The scenarios for information transmission errors are generated by the Monte Carlo simulation (MCS), besides uncertain physical parameters, e.g., the output power of renewable distributed generations (DGs). Afterward, the clustering algorithms are used to reduce the number of scenarios. In this paper, the k-means clustering algorithm has been selected to cluster the scenarios. The introduced clustering-based method is applied to a CPMG, and test results are compared to available MCS-based studies. The inaccuracy of the proposed clustering-based method is less than 3%, while its execution time is about 22 times faster than MCS-based ones. The comparative test results under various scenarios like available methods, neglecting the cyber failures and information errors illustrate the advantages of this research. The comparative test results illustrate the accuracy of the reliability calculations, while the execution time is desired.

Thermo-physical evaluation of firefighter outer garment in high flux environments

Thermal protective performance tests have been conducted and improved over the years to assess the safety provided by firefighters’ outer thermal garments. Existing evaluation criteria based on empirical relations require an iterative process to estimate skin burn injuries. In this work, the concept of critical time – maximum exposure time before physical failure, is proposed, and utilized to abate this iterative process. The critical time relation to the fabric performance is investigated at an incident heat flux of 41, 84 and 126 kW/m2. Furthermore, parametric studies are performed to characterize the fabric thermo-physical behavior and associated burn degree. The tested specimens consist of an outer shell, a moisture barrier and a thermal liner. The methodology of visual assessment as per ISO 6942 is implemented to approximate the critical time. The critical time relation to increasing incident heat flux displayed a nonlinear performance reduction in the garment. An increase in the second degree burn time was observed for a vertically oriented bench-scale test. The firefighter’s current outer garment failed at a high flux of 126 kW/m2. The concept of relating the critical time to cumulative incident flux will aid the education of firefighters on fluctuating fire environments. This research opens a new domain to analyse the protective garments utilising the critical time.

Inspection of Synchronous Belt in Lifting Appliances

Introduced the inspection requirements of the main transmission components in the hoisting machinery in the current special equipment regulation; Checked the technical requirements related to safety in the relevant standards of the synchronous belt. Based on the physical structure, failure mode and regulatory standard requirements of the synchronous belt, summarized the inspection method of the synchronous belt.

Applying a Generalized FMEA Framework to an Oil Sands Tailings Dam Closure Plan in Alberta, Canada

Historically, tailings facilities have been designed primarily with consideration of the mine’s active life. This is problematic, as the lifespan of a tailings dam may far exceed the life of the mine. Over time, it is expected that these structures will transform into a mine waste structure and then eventually a landform. In Alberta, Canada, dam owners can submit a decommissioning, closure, and abandonment (DCA) plan and completion reports to apply for the facility to be de-registered as a dam. If successful, the structure would be considered a solid waste structure and may be reclassified and regulated as a mine waste dump. The Alberta Energy Regulator expects DCAs to be accompanied and supported by risk assessments that consider long-term physical failure modes, including failure modes that may not be applicable during operations, in accordance with Manual 019. To help support the process of de-registering a tailings dam, a risk management tool, referred to as a Generalized Failure Modes Effects (G-FMEA) framework, was developed and presented in the Journal of Minerals in the Special Issue Tailings Dams: Design, Characterization, Monitoring, and Risk Assessment. The G-FMEA was designed to be used for assessing risks of an external tailings facility in closure, with the goal of assessing the long-term risk of geotechnical failure to support the process of de-registration. In Alberta, a number of tailings dams are undergoing closure and reclamation activities. This paper applies the developed G-FMEA framework to an oil sands tailings dam in Alberta to demonstrate the application of the framework. The paper assesses two specific failure modes of two different elements, including clogging of the drains and surface erosion of the berm. The failure modes are assessed over different timescales to demonstrate how the consequence, likelihood, and risk rating may change over time. The results of this process are discussed in the context of the potential for the facility to be de-registered as a dam.

Investigation on the Properties of Gneiss under Different Ground Stresses.

Initial geostress has great influence on the properties of gneiss. The physical and mechanical properties of gneiss vary considerably due to different initial geostresses, which exert a huge effect on the stability of underground engineering. In order to explore the influence of initial ground stress on the properties of gneiss. Changes in the physical properties (e.g., P-wave velocity and volumetric weight), mechanical properties (e.g., compressive strength, elastic modulus, and residual strength) and failure mode of gneiss are analyzed by conducting physical and mechanical tests on gneiss in different ground stress areas. The results show that high geostress can improve the pre-peak mechanical properties of gneiss, and weaken its post-peak mechanical properties. When the initial geostress is greater, the pre-peak mechanical properties are better, and the post-peak mechanical properties are worse. The failure mode of gneiss under high ground stress is primarily brittle failure. When the initial ground stress is greater, brittleness is stronger. According to the research results of this paper, it can provide the basis for the optimization and improvement of underground engineering support in gneiss strata with high geostress. The research results have important reference value and guiding significance for underground engineering construction in high geostress gneiss areas.

A Controller Switching Mechanism for Resilient Wireless Sensor–Actuator Networks

Controller failures can result in unsafe physical plant operations and deteriorated performance in industrial cyber–physical systems. In this paper, we present a controller switching mechanism over wireless sensor–actuator networks to enhance the resiliency of control systems against problems and potential physical failures. The proposed mechanism detects controller failures and quickly switches to the backup controller to ensure the stability of the control system in case the primary controller fails. To show the efficacy of our proposed method, we conduct a performance evaluation using a hardware-in-the-loop testbed that considers both the actual wireless network protocol and the simulated physical system. Results demonstrate that the proposed scheme recovers quickly by switching to a backup controller in the case of controller failure.

A fault-tolerance control method of load frequency based on reverse behavior reconstruction

The access of a high proportion of renewable energy and the large-scale application of open sharing communication network are the two main characteristics of modern interconnected power grid. However, the tight coupling between the cyber and physical subsystem makes the malicious network attack and sudden physical failure more likely to cause the collapse of the interconnected power grid. Therefore, a reverse behavior reconstruction strategy is proposed, which does not need to obtain a priori fault information and only depends on the input and output measurements of the system, so as to realize fault tolerance as much as possible. The simulation experiments show that the proposed strategy can achieve the frequency fault tolerance and has better practicability and applicability under complex and diverse fault conditions.

Simulation-based study of single-event burnout in 4H-SiC high-voltage vertical superjunction DMOSFET: Physical failure mechanism and robustness vs performance tradeoffs

We explore and elucidate physical failure mechanisms in a 4H-SiC, high voltage, superjunction (SJ) vertical DMOSFET from a single heavy ion strike using three-dimensional electro-thermal transient simulations. The single-event burnout (SEB) failure is thermal runaway from second breakdown, initiated by impact ionization and terminated with mesoplasma formation, at the center of the P-pillar/N+ substrate interface. We also demonstrate that the SEB performance of this SiC SJ DMOSFET is insensitive to the pillar width but sensitive to the strike location with ion strike at the P-pillar causing SEB at a lower blocking voltage than at the N-pillar. Compared to commercially available 1.2 kV blocking-rated non-SJ DMOSFETs, which have been demonstrated to survive SEB up to 525 V, the SJ DMOSFET increases SEB survival threshold voltage (VSEB) by a factor of 2.2, making it close to 1200 V, while the on-resistance is increased by only 11%. Using our recently developed figure of merit (FoM), which considers the trade-off between VSEB and on-state performance, we find that the SiC SJ DMOSFET achieves a FoM that is 14 times better, making it superior to conventional 1.2 kV SiC DMOSFETs for long-term radiation-tolerant operation in space applications.

The Construction of University Network Education System Based on Mobile Edge Computing in the Era of Big Data

This article first established a university network education system model based on physical failure repair behavior at the big data infrastructure layer and then examined in depth the complex common causes of multiple data failures in the big data environment caused by a single physical machine failure, all based on the principle of mobile edge computing. At the application service layer, a performance model based on queuing theory is first established, with the amount of available resources as a conditional parameter. The model examines important events in mobile edge computing, such as queue overflow and timeout failure. The impact of failure repair behavior on the random change of system dynamic energy consumption is thoroughly investigated, and a system energy consumption model is developed as a result. The network education system in colleges and universities includes a user login module, teaching resource management module, student and teacher management module, online teaching management module, student achievement management module, student homework management module, system data management module, and other business functions. Later, the theory of mobile edge computing proposed a set of comprehensive evaluation indicators that characterize the relevance, such as expected performance and expected energy consumption. Based on these evaluation indicators, a new indicator was proposed to quantify the complex constraint relationship. Finally, a functional use case test was conducted, focusing on testing the query function of online education information; a performance test was conducted in the software operating environment, following the development of the test scenario, and the server’s CPU utilization rate was tested while the software was running. The results show that the designed network education platform is relatively stable and can withstand user access pressure. The performance ratio indicator can effectively assist the cloud computing system in selecting a more appropriate option for the migrated traditional service system.