Weibull Distribution Analysis Research Articles

Experimental and Statistical Investigations for Tensile Properties of Hemp Fibers

This study investigated the tensile behaviors of hemp fiber bundles and examined how properties including tensile strength and Young’s modulus vary with the bundle diameter. Hemp fibers were extracted, degummed, and separated into bundles of different diameters ranging from less than 50 μm to over 150 μm. Tensile tests were conducted on these fiber bundles using a rheometer-based tensile testing machine. The results showed that hemp fibers exhibited a tensile strength of 97.33 MPa and a Young’s modulus of 3.77 GPa at a 50% survival probability. However, the scale parameters for breaking stress and Young’s modulus were determined to be 620.57 MPa and 29.88 GPa, respectively. As the fiber bundle diameter increased, the tensile strength decreased significantly. This was attributed to the higher probability of defects and irregularities acting as weakness points in larger fiber bundles. In contrast, Young’s modulus (stiffness) increased with increasing bundle diameter, likely due to improved fiber–fiber interactions. To further understand the variability and reliability of the tensile properties, statistical models were developed. The Weibull distribution analysis was applied, revealing critical insights into the variability of diameter, stress at break, Young’s modulus, and strain at break. The Weibull parameters provided a comprehensive understanding of the fibers’ mechanical reliability. Additionally, the Griffith model was employed to predict the strength and Young’s modulus based on fiber diameters, supporting the observation that thinner fibers generally exhibited higher tensile strength due to fewer defects. Overall, this work highlights the importance of understanding structure–property relationships in natural fibers like hemp for optimizing their performance in composites.

Adhesion Mechanics and Detachment Dynamics of Vanishing Surface Layers on Hydrogels.

Cross-linked hydrogel surfaces exhibit reduced stiffness when polymerized against polymeric hydrophobic surfaces. As such, these layers play a critical role in contact mechanics, particularly exhibiting strong relative adhesion with colloidal probes when the contact area is small. This prevents the use of continuum models of adhesive soft contact. To connect mechanisms of stretch to the force response, depth-controlled nanoindentation experiments were conducted on polyacrylamide (pAAM) hydrogel samples using colloidal probe atomic force microscopy (AFM). The pAAM sample had a high water content of >90% and was molded against polyoxymethylene (POM) to create a more dilute surface layer with thickness ∼0.5 μm. Indentations to multiple depths between 50 nm and 1.25 μm were repeated 10 times each. First, the force drops during the unloading, and separation segments of each indentation were characterized. This described the detachment progression for increasing areas of contact, revealing that the pull-off force for a single chain was in the single-pN range. Second, the stretched polymer network was modeled as an array of parallel, linear springs. Assuming a constant areal chain density of α = 100 chains/μm2, the maximum force of adhesion was plotted versus the volume of chains stretched upward, and the average chain stiffness was calculated from a linear fit to be 22.8 × 10-6 N/m. A Weibull distribution analysis of detachment events revealed a dependence of chain stiffness on maximum indentation depth (dmax), with higher stiffness at shallower depths approaching kchain ≈ 20 × 10-6 N/m. These findings on adhesion mechanics between a vanishing hydrogel surface and probe can guide the development of multifunctional hydrogels for various biomedical applications.

Safety assessment of anti-B cell maturation antigen chimeric antigen receptor T cell therapy: a real-world study based on the FDA adverse event reporting system database.

On April 18, 2024, the U.S. Food and Drug Administration officially required updating of the "boxed warning" for T cell malignancies for all chimeric antigen receptor T cell (CAR-T) therapies. Given the clinical significance of these therapies, a rigorous safety assessment is paramount. However, comprehensive real-world safety studies have been lacking for the newly marketed CAR-T products idecabtagene vicleucel (ide-cel) and ciltacabtagene autoleucel (cilta-cel), which target B cell maturation antigen, especially regarding the risk of secondary malignancies. Therefore, we aimed to thoroughly analyze the adverse events (AEs) information in the FDA Adverse Event Reporting System (FAERS) database to comprehensively understand the safety risks of ide-cel and cilta-cel. We extracted AE reports related to ide-cel and cilta-cel from the FAERS database (https://fis.fda.gov/extensions/FPD-QDE-FAERS/FPD-QDE-FAERS.html.) from January 1, 2019 to December 31, 2023. Disproportionality analysis and Bayesian analysis were used to identify risk signals across subgroups and specific cases (including for death and secondary malignancies). Weibull distribution analysis was employed to determine the time to AE onset. A total of 695 AE reports for ide-cel and 848 for cilta-cel were included in the FAERS database. This analysis identified 81 positive signals for ide-cel and 74 for cilta-cel. Notably, comparisons with the drug labels revealed "unexpected signals," including febrile bone marrow aplasia (reporting odds ratio=69.10; confidence interval 39.12-122.03) and plasma cell myeloma (12.45; 8.18-18.95) for ide-cel, and increased serum ferritin (24.98; 8.0-77.58) and large intestine perforation (18.57; 5.98-57.69) for cilta-cel. Both drugs showed a higher AE incidence among male recipients and patients aged ≥65 years, although female recipients faced a greater risk. Most AEs occurred at the early stage of administration. However, secondary malignancies were detected for both drugs, primarily occurring one-year post-administration. This study provides a foundation for understanding the safety profile of CAR-T cell therapy, particularly in relation to the emergence of secondary malignancies. Such insights are helpful for clinical decision-making and the safe and effective utilization of these therapeutic agents.

Static mechanical properties and failure behaviors of self-piercing riveted joints in aluminum alloy 5A06 after aging

This paper conducts an investigation on the static mechanical properties and failure behavior of self-piercing riveted joints in aluminum alloy 5A06 after being subjected to the aging process. The study involves three distinct categories of joint specimens: original specimens, 1-year aged specimens and 1-year aged specimens that have been additionally heat-treated at 200 °C. The research findings affirm that strain aging is responsible for a reduction in the peak strength of the joints. Furthermore, the weakest failure chain within the self-piercing riveted joint shifts towards the upper sheet due to a more significant reduction in internal stress experienced by the upper plate. This leads to a failure model characterized by upper sheet pull-off. Through Weibull distribution analysis, it has been established that the 5 % lower limit value for the strength of the SPR joint experiences an 86 % decline following 1-year aging. In practical terms, this means that for a vehicle structure with 7000 riveting points will lose an overall structural strength equivalent to the initial strength of 1000 riveting points within one year.

Artificial neural network-based approach for prediction of nanomechanical properties of anodic coating on additively manufactured Al–10Si–Mg alloy

Nowadays, anodic coating on additively manufactured (AM) or 3D printed Al–10Si–Mg alloy are used for various components in spacecraft such as antenna feeds, wave guides, structural brackets, collimators, thermal radiators etc. In this study, artificial neural network (ANN) and power law-based models are developed from experimental nanoindentation data for predicting elastic modulus and hardness of anodized AM Al–10Si–Mg at any desired loads. Data from nanoindentation experiments conducted on plan- and cross-sections of anodized coating on AM Al–10Si–Mg alloy was considered for modeling. Apart from nanomechanical properties, load and displacement curves were predicted using Python software from ANN and the Power law model of nanoindentation. It is observed that the ANN model of 50 mN nanoindentation experimental data can accurately predict the loading pattern at any desired load below 50 mN. Elastic modulus and hardness of anodized AM Al–10Si–Mg computed from ANN and the power law model of the unloading curve are also comparable with the values obtained from Weibull distribution analysis reported elsewhere. The derived models were also used to predict nanomechanical properties at 25 and 35 mN, for which no experimental data was available. The computed hardness of plan section of the anodic coating is 3.99 and 4.02 GPa for 25 and 35 mN, respectively. The computed hardness of cross-section of the anodic coating of is 7.16 and 6.61 GPa for 25 and 35 mN, respectively. Thus, the ANN and Power law model of nanoindentation can predict elastic modulus and hardness at different loads by conducting the minimum number of experiments. The novel approach to predict nanomechanical properties using ANN resulted in determining realistic and design specific data on hardness and modulus of the anodized coating on AM Al–10Si–Mg alloy.

Multilevel resistive switching in hydrothermally synthesized FeWO4 thin film-based memristive device for non-volatile memory application

The memristors offer significant advantages as a key element in non-volatile and brain-inspired neuromorphic systems because of their salient features such as remarkable endurance, ability to store multiple bits, fast operation speed, and extremely low energy usage. This work reports the resistive switching (RS) characteristics of the hydrothermally synthesized iron tungstate (FeWO4) based thin film memristive device. The detailed physicochemical analysis was investigated using Rietveld’s refinement, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) techniques. The fabricated Ag/FWO/FTO memristive device exhibits bipolar resistive switching (BRS) behavior. In addition, the devices exhibit negative differential resistance (NDR) at both positive and negative bias. The charge-flux relation portrayed the non-ideal or memristive nature of the devices. The reliability in the RS process was analyzed in detail using Weibull distribution and time series analysis techniques. The device exhibits stable and multilevel endurance and retention characteristics which demonstrates the suitability of the device for the high-density non-volatile memory application. The current conduction of the device was dominated by Ohmic and trap controlled-space charge limited current (TC-SCLC) mechanisms and filamentary RS process responsible for the BRS in the device. In a nutshell, the present investigations reveal the potential use of the iron tungstate for the fabrication of memristive devices for the non-volatile memory application.

Revalorization of cellulosic fiber extracted from the waste stem of Brassica oleracea var. botrytis L. (cauliflower) by characterizing for potential composite applications

This study investigates a protocol for extracting and characterizing fibers obtained from cauliflower (Brassica oleracea var. botrytis L.) stem agricultural waste, exploring its suitability for composite applications. Brassica oleracea var. botrytis L. (BOVBL), commonly known as cauliflower, was comprehensively characterized for the first time, with its fiber extracted from plant waste stems. BOVBL fiber, subjected to microbial degradation, exhibited properties typical of natural fibers, with a density of 1.47 g/cm3 and a composition of 50.09 % cellulose, 19.7 % hemicellulose, and 22.3 % lignin. XPS analysis showed that the surface structure of the fiber consisted of carbon (64.37 %) and oxygen (22.36 %) due to cellulose. The crystalline index is calculated as 57.32 % indicating a highly organized molecular arrangement. SEM images depicted a rough surface with hexagonal and rectangular forms, enhancing resin penetration for improved composite adhesion. The thermal analysis demonstrated stability up to 324.38 °C, promising suitability for composite heat processing. The results of the single fiber test (tensile strength, E-modulus, and elongation at break) were assessed by using Weibull distribution analysis. This investigation provides suggestions for the potential applications of organic waste leftovers as a new, environmentally friendly material for fiber-reinforced polymer composites aligning with circular economy and sustainability through the utilization of agricultural waste in the future.

Comparison of fresh and hardened properties of concrete made with various artificial and natural sands

Concretes made with different fine aggregates (natural river sand, artificial crushed sand, artificial gravel sand and a hybrid sand (50% river sand and 50% gravel sand by mass)) were experimentally investigated. The concretes were found to have little differences in compressive strength and elastic modulus (less than 6.4%). Compared with the concrete made with natural river sand, the concretes made with artificial sands demonstrated higher flexural strengths (3.5–11.1%) and splitting strengths (4.4–12.8%) at 28 days, but lower workability (21.4–35.7%), water permeation resistance (34.3–53.7%) and abrasion resistance (2.9–20.6%). The compressive, flexural and splitting tensile strengths of the concretes increased with time under water curing. Under sulfate attack, the compressive strengths of the concretes were enhanced at 56 days but reduced at 90 days. In comparison with water curing, the reductions in compressive strength due to sulfate attack were 2.6–7.7% at 56 days and 11.8–24.4% at 90 days. Weibull distribution analysis was conducted to explore the sensitivity of concrete strength to the type of fine aggregate.

Lightning impulse breakdown behavior of natural ester and modified natural ester under long oil gap: An experiment and first-principles simulation analysis

The investigation of lightning impulse (LI) breakdown characteristics in long oil gaps with insulating liquids is of utmost importance for the design of high-voltage, large-capacity transformers. This study focuses on analyzing the negative LI breakdown characteristics of two types of insulating oils, namely high viscosity natural ester soybean oil (SO) and low viscosity modified natural ester palm fatty acid ester (PFAE), under long oil gap conditions. The research includes testing and analyzing the voltage and current waveforms, LI breakdown voltage, and streamer discharge development speed of these liquids across oil gaps ranging from 25 mm to 105 mm. The findings demonstrate that the breakdown voltage of both insulating oils tends to increase as the oil gap distance widens. At a 25 mm gap, the average breakdown voltage of PFAE is not significantly different from that of SO. However, at a 105 mm gap, the average breakdown voltage of PFAE surpasses that of SO by 46.29%. Weibull distribution analysis is applied to the LI breakdown voltage data of the two insulating liquids, resulting in empirical formulas for breakdown voltage as a function of oil gap width at failure probabilities of 1%, 50%, and 90%. The discharge development rate of PFAE is lower than that of SO, especially in the oil gap of 105 mm. With the increase of the oil gap, the streamer development rate of the two insulating oils showed a trend of increasing. Using density functional theory based on first principles, the study investigates changes and discrepancies in parameters such as ionization potential, electron affinity, softness, excitation energy, and molecular surface electrostatic potential of the two insulating liquids with varying electric field strengths. The atomic and molecular scale analysis reveals the primary factors contributing to the contrasting macroscopic lightning shock breakdown characteristics of SO and PFAE. The comprehensive combination of experimental and simulation results suggests that PFAE exhibits greater potential for implementation in high-voltage, large-capacity transformers compared to SO. This study aims to bridge the gap in knowledge regarding the LI breakdown characteristics of different natural esters in long oil gaps. The experimental and theoretical findings presented in this paper provide a foundation for the practical application of natural esters and modified natural esters in high-voltage and large-capacity transformers.

Impact resistance and flexural behavior of U-shaped concrete specimen retrofitted with polyurethane grout

Normal concrete-polyurethane grout (NC-PUG) composite U-shaped and beam specimens were developed in this study to evaluate the capability and efficacy of PU grouting material prepared from mixing bio-based polyurethane (PU) and quartz sand as a coating material. The composite specimens were subjected to dynamic and flexural loads using U-shaped drop-weight impact test (USDWIT) and three-point bending test, respectively. Various PUG overlaid thicknesses and configurations were adopted to improve the impact and flexural behavior of the concrete. Weibull distribution analysis was performed on the USDWIT result. The result indicated that the reference NC-PUG beam exhibited the highest load-carrying capacity of 18.26 kN and the lowest ultimate deflection of 0.52 mm compared to the composite NC-PUG specimens. While, the NC beam retrofitted with a 10 mm thickness overlaid at the top surface (NC-PUGT10) revealed a reduced ultimate load-carrying capacity compared to the reference NC-PUG specimen. The impact performance of the composite U-shaped NC-PUG specimen have remarkably improved due to the influence of PU grouting materials overlaid, with a higher ductility index, which tends to change the brittle nature of concrete to a ductile state. The energy absorption capacity at the failure stage of the NC-PUGT5 is 16 times that of the reference U-shaped NC-PUG specimen. The NC-PUGTB5 and NC-PUGT10 revealed impact strength, which is 52.28 times and 68.1 times more than the reference specimens, respectively. Reliability analysis indicated that about 80% of the U-shaped NC-PUG specimen can withstand 63 impact times at the failure stage. The finding showed that retrofitting concrete structures with PUG material is a promising and sustainable method to protect the concrete structure against dynamic loads

Impact resistance of micro and macro crimped steel fibre reinforced self-compacting concrete with SCM

This paper aims to investigate the impact resistance of micro and macro crimped steel fibre-reinforced self-compacting concrete (SFRSCC) with the volume fractions of 0.25%, 0.50%, and 0.75%. A total of seven mixtures were investigated with different volume fractions of steel fibres considering in terms of fresh, mechanical properties and impact resistance. The total binder contains 60% cement and 40% supplementary cementitious materials (SCM) with a combination of 30% fly ash and 10% silica fume. The addition of steel fibre decreases the workability of SCC. However, the inclusion of SCM compensates and increases its workability. Mechanical behaviour of micro and macro steel fibre reinforced SCC outperforms the conventional SCC in terms of compressive strength, split tensile strength and flexural strength. The impact resistance of SFRSCC is determined through a modified testing procedure derived from the guidelines provided by ACI 544.2 R. It is observed that the volume fraction of both 0.75% micro and macro steel fibre has improved impact resistance with increase percentage of energy absorption of 180% and 240%. The relationship between UPV and impact test results found that the number of blows can be predicted using the UPV values from the regression equations. The results of the Weibull distribution (WD) and reliability analysis indicate that 80% (τ = 0.8) of the SFRSCC samples are reliable enough to survive 14 blows at first crack and 20 blows at failure crack. The incorporation of crimped steel fibres into the concrete matrix led to the even distribution of impact loading throughout the concrete specimen with the help of steel fibres, thereby improving the impact resistance of SCC.

In-Vitro Comparison of Fracture Strength of Endocrowns and Overlays in Endodontically Treated Teeth Manufactured with Monolithic Lithium Disilicate and Zirconia.

To evaluate the fracture strength and the failure mode of endodontically treated molars restored with monolithic lithium disilicate and zirconia endocrowns and overlays. A total of 48 extracted mandibular molars were endodontically treated, decoronated 2 mm above the cementoenamel junction and divided into four 12-specimen groups. Group ELD: lithium disilicate endocrowns. Group EZ: monolithic zirconia endocrowns. Group OLD: lithium disilicate overlays. Group OZ: monolithic zirconia overlays. Overlays did not extend in the pulp chamber and endocrowns extended in the pulp chamber 2 mm. After adhesive bonding of the restorations, the specimens were subjected to thermocycling (×5000 cycles) and then to fracture resistance testing at lateral static loading (1 mm/min) at a universal testing machine. The failure mode of the specimens was qualitatively evaluated. Differences in means were compared using with t-tests for independent samples or Mann-Whitney test (p < 0.05). Weibull distribution analysis was also performed. Group ELD showed significantly higher fracture strength than all other groups (p = 0.001), and the highest Weibull modulus. Conclusions: Lithium disilicate endocrowns exhibit higher fracture strength and are more reliable compared to the other types of restorations examined. Endocrowns had more catastrophic failures compared to overlays.

Characterization of Electromechanical Delamination Behaviors in Practical REBCO Coated Conductor Tapes Under Transverse Tension at 77 K

In high-temperature superconducting coils, the high transport current density and magnetic field generate a large electromagnetic force on REBCO-coated conductor (CC) tapes. A large Lorentz force can cause interlayer delamination damage to the CC tape under radial or transverse tensile loads. The structural delamination characteristics of multilayered REBCO CC tape are essential for the fabrication of mechanically reliable CC coils. In this study, the electromechanical delamination behaviors of practical REBCO CC tapes were characterized using an anvil test method. Our recently established continuous critical current, I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> measurement system was used to minimize the test time and can directly evaluate the effect of the transverse tensile load on I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> behavior without time-consuming intermittent I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> measurements during testing. Characterization of the delamination mechanism, including damage initiation, was performed through scanning electron microscopy observation of the fractured sample. Two-parameter Weibull distribution analysis was used to specify the data scattering of the electromechanical delamination strength.

Objective Bayesian analysis of Marshall-Olkin bivariate Weibull distribution with partial information

ABSTRACT In competing risks problem, a subset of risks is needed more attention for inferential purposes. In the objective Bayesian paradigm, reference priors enable to achieve such inferential objectives. In this article, the Marshall-Olkin bivariate Weibull distribution is considered to model the competing risks data. In the availability of partial information for some of the parameters, the reference priors are derived as per the importance of the parameters. The Dirichlet prior is taken as a conditional subjective prior and the marginal reference prior has been derived. Also, the propriety of the resulting posterior density has been proved. The Bayesian estimates of the parameters are obtained under squared error and linear-exponential loss functions. Further, the derived reference prior is used for the computation of Bayes factors or posterior odds in testing the hypothesis that the competing risks are identical. The performance of established Bayesian estimators is illustrated using the Diabetic Retinopathy Study (DRS) and Prostate Cancer data sets. Finally, the model compatibility is done for the considered data sets under Bayesian Paradigm.

Characterization of new natural cellulosic fiber from Calamus tenuis (Jati Bet) cane as a potential reinforcement for polymer composites

This study investigates the physical, structural, chemical, thermal, mechanical, and morphological properties of the fibers of Calamus tenuis canes and compares the findings with various lignocellulosic fibers to find the place of these fibers as reinforcements for polymer composites. Chemical analysis confirms the presence of 37.43 ± 1.40% cellulose, 31.06 ± 1.03% hemicellulose, and 28.42 ± 0.81% lignin in Calamus tenuis cane fibers, moreover, the presence of these constituents is also confirmed by Fourier Transformed Infrared Spectroscopic (FTIR) analysis. The X-Ray diffraction (XRD) analysis determines the crystallinity index of 37.38 ± 0.27% and the crystallite size of 0.87 ± 0.03 nm of the samples. The thermogravimetric analysis ensures that the Calamus tenuis cane fibers are thermally stable up to 210 ± 5 °C. The Weibull distribution analysis is employed to estimate the tensile properties of Calamus tenuis canes, which reveal a tensile strength of 37.5 ± 2 MPa, Young's modulus of 1.05 ± 0.08 GPa, and an elongation at break of 18.94 ± 4.26%. The roughness of the fibers' outer surface is confirmed by SEM micrographs and AFM analysis, suggesting that it could enhance the adhesion between fibers and matrix during the fabrication of composites.

Superior Enhancement of the UHMWPE Fiber/Epoxy Interface through the Combination of Plasma Treatment and Polypyrrole In-Situ Grown Fibers.

Obtaining a robust fiber/matrix interface is crucial for enhancing the mechanical performance of fiber-reinforced composites. This study addresses the issue by presenting a novel physical-chemical modification method to improve the interfacial property of an ultra-high molecular weight polyethylene (UHMWPE) fiber and epoxy resin. The UHMWPE fiber was successfully grafted with polypyrrole (PPy) for the first time after a plasma treatment in an atmosphere of mixed oxygen and nitrogen. The results demonstrated that the maximum value of the interfacial shear strength (IFSS) of the UHMWPE fiber/epoxy reached 15.75 MPa, which was significantly enhanced by 357% compared to the pristine UHMWPE fiber. Meanwhile, the tensile strength of the UHMWPE fiber was only slightly reduced by 7.3%, which was furtherly verified by the Weibull distribution analysis. The surface morphology and structure of the PPy in-situ grown UHMWPE fibers were studied using SEM, FTIR, and contact angle measurement. The results showed that the enhancement of the interfacial performance was attributed to the increased fiber surface roughness and in-situ grown groups, which improved the surface wettability between the UHMWPE fibers and epoxy resins.

QUANTIFYING SULFUR DISPERSION USING POPULATION SURVIVAL ANALYSIS OF TENSILE STRENGTH

ABSTRACT High-performance rubber compounds require good dispersion of polymers, fillers, and other additives. However, fine powdery additives such as zinc oxide and insoluble sulfur (IS) are characteristically difficult to disperse, and poor dispersion may lead to large crosslink and modulus gradients in the final vulcanizate. IS dispersion can be assessed directly or indirectly, yet many techniques suffer from a lack of sensitivity and accuracy or are cost prohibitive. Herein, we describe the application of a two-parameter Weibull distribution and population survival analysis of cured rubber tensile strength as a simple technique to evaluate IS dispersion. We use statistical tools to determine the optimum number of sample replicates required to differentiate the quality of dispersion in rubber articles through the Weibull scale and shape estimates (α and β, respectively). We then demonstrate how mixing cycle time and intensity affect the dispersion of two IS grades and show that judicious choice of IS can lead to reduced cycle mix times, productivity improvements, and energy cost savings.

Digitalization of Distribution Transformer Failure Probability Using Weibull Approach towards Digital Transformation of Power Distribution Systems

Digitalization of the failure-probability modeling of crucial components in power-distribution systems is important for improving risk and reliability analysis for system-maintenance and asset-management practices. This paper aims to implement a Python programming-based Weibull approach for digitalization of distribution-transformer (DT) failures, considering a regional section of DTs in Sri Lanka as a case study. A comprehensive analysis for DT-failure data for six years has been utilized to derive a Weibull distribution analysis for DTs. The interpretation of the resulting beta and alpha parameters of the Weibull analysis for different categories of DTs in the selected region is also presented. The resulting data can be uploaded to computerized maintenance-management systems (CMMS), to adopt conclusions or resolutions reached by the asset and maintenance managers. Ultimately, failure-probability modeling is beneficial for decision-making processes for higher management aiming for the digital transformation of power-distribution systems.

Statistical Analysis of Alpha Power Inverse Weibull Distribution under Hybrid Censored Scheme with Applications to Ball Bearings Technology and Biomedical Data

Applications in medical technology have a massive contribution to the treatment of patients. One of the attractive tools is ball bearings. These balls support the load of the application as well as minimize friction between the surfaces. If a heavy load is applied to a ball bearing, there is the risk that the balls may be damaged and cause the bearing to fail earlier. Hence, we aim to study the model of the failure times of ball bearings. A hybrid Type-II censoring scheme is recommended to minimize the experimental time and cost where the components are following alpha power inverse Weibull distribution. A ball bearing is one example; the other is the resistance of guinea pigs exposed to dosages of virulent tubercle bacilli. We use different estimation methods to obtain point and interval estimates of the unknown parameters of the distribution; consequently, estimating statistical functions such as the hazard rate and the survival functions are observed. The maximum likelihood method and the maximum product spacing methods are used, in addition to the Bayesian estimation method, in which symmetric and asymmetric loss functions are utilized. Interval estimators are obtained for the unknown parameters using three different criteria: approximate, credible, and bootstrap confidence intervals. The performance of the parameters’ estimation is accomplished via simulation analysis and numerical methods such as Newton–Raphson and Monte Carlo Markov chains. Finally, results and conclusions support the suitability of alpha power inverse Weibull distribution under a hybrid Type-II censoring scheme for modeling real biomedical data.

The size-dependence of compressive mechanical properties and serrated-flow behavior of Ti-based bulk metallic glass

In this work, the size-dependence on the compressive mechanical and serrated-flow behaviors of Ti-based bulk metallic glass (BMG) was systematically investigated. The results demonstrated that the compressive plasticity of the BMGs was greatly improved from 1.0 ± 0.6% to 2.4 ± 0.5% with the specimen diameter reducing from 4 to 2 mm, while the fracture strength decreased from 2070 ± 40 to 1870 ± 31 MPa, indicating a trend of smaller and softer characteristics. Meanwhile, the Weibull distribution analysis of the strength and plasticity indicated that when the specimen diameter was increased from 2 to 4 mm, the Weibull strength modulus (mσ) decreased from 83.5 to 46.6 and the Weibull plasticity modulus (mε) decreased from 0.70 to 0.36, revealing a more discrete distribution of both the strength and the plasticity with the increase in diameter. The average shear-band velocity (ASBV), which was calculated based on the stick–slip dynamics, indicated an increasing trend with the increase in specimen diameter, while the shear-band instability index (SBI) presented a similar increasing trend. Meanwhile, the serrated-flow analysis revealed that the BMG specimen with smaller size possessed a lower average stress drop and a larger Weibull modulus of stress drop, which is the substantial cause for the considerable malleability in smaller specimen. Moreover, the fitting result for the cumulative probability distributions of the stress drop indicated that the stress drops in smaller specimens exhibit better coincidence.