Lifetime Of Components Research Articles

An Ontology‐Augmented Digital Twin for Fiber‐Reinforced Polymer Structures at the Example of Wind Turbine Rotor Blades

A methodology for establishing a structural digital twin is proposed to facilitate the lifetime prediction of fiber‐reinforced polymer (FRP) structures, in this case, a wind turbine rotor blade. The digital twin incorporates production peculiarities and imperfections occurring during the manufacturing process of the FRP component. The methodology involves the computation of process‐defined effective elastic properties and residual stresses through numerical simulation of the resin cure cycle. The results are then transferred to a structural finite‐element model. By applying local wind conditions to this model, a comprehensive state of stress is obtained. This serves as a basis for a practical evaluation of material fatigue within the composite, leading to the prediction of the component's lifetime. The entire workflow is implemented in a Jupyter‐based application that uses an ontology with an appertaining knowledge graph to facilitate the transfer of intermediate results between the observation scales and process steps of the digital twin. In line with the principles of open science, the methodology utilizes open‐source software.

Differentiation of Tumors of the Upper Respiratory Tract Using Optical Metabolic Imaging.

With over 184,000 new cases and more than 99,000 deaths per year, malignancies of the larynx are a global health problem. Currently, a dedicated screening method enabling a direct onsite diagnosis is missing. This can lead to delayed diagnosis and worse outcomes of the patients. An endoscopic optical method enabling a direct distinction between healthy tissue, dysplastic tissue and cancerous tissue would be an ideal tool for the detection of tumors of the upper aerodigestive tract (UADT). Healthy and tumor cells differ significantly in their metabolic state due to the different metabolic pathways they use (more oxidative phosphorylation in healthy cells, more glycolysis in tumor cells). Optical metabolic imaging (OMI) measuring relative intracellular concentration of NAD(P)H and FAD redox pairs could be a promising approach for early tumor detection and differentiation of suspicious mucosal lesions. In this study, a specially designed endoscopic two-beam two-photon fluorescence lifetime imaging (FLIM) system was used to perform two-photon two-beam FLIM of NAD(P)H and FAD to image the metabolic state in different tissue samples of the UADT. FLIM data sets of 27 tissue samples from 16 patients were recorded directly after surgery ex vivo in a special tissue culture medium at 37°C on a dedicated microscope using multiphoton excitation. Based on the FLIM measurements of NAD(P)H and FAD, six of the most common indices for the characterization of the cells' metabolism were calculated. Three of them, the ratio of the exponential coefficients (amplitudes) of the short and long lifetime components both for NAD(P)H and FAD (NAD(P)H a1/a2 ratio and FAD a1/a2 ratio) and the fluorescence lifetime redox ratio (FLIRR) enabled differentiation between healthy tissue, benign lesions, dysplastic tissue, and cancer tissue with statistical significance. We showed by measurements on freshly collected tissue samples that mucosal lesions of the UADT can be differentiated using our newly designed endoscopic FLIM device. In vivo measurements in healthy volunteers were also possible. By means of this technology, differentiation of cancerous, pre-cancerous, and healthy tissue in the UADT by OMI could be possible. Of six indices used to characterize cell metabolism we calculated, the FLIRR showed the most significant differences between tissue types.

Emissive Features of Perylene Diimide Derivative with β-Cyclodextrin: Probing the role of inter and intramolecular interactions.

Perylene diimide (PDI) derivatives have been extensively explored as chromophoric dyes for functional organic materials. Here, the custom synthesized tyrosine appended perylene diimide (PDI-Tyr) derivative has shown strong aggregation in aqueous medium diminishing its emissive features, which was surpassed by the supramolecular interaction with β-cyclodextrin (β-CD). Complex formation between PDI-Tyr and β-CD, proposed from the absorption and emission studies, have been substantiated by the 1H-NMR, ITC and geometry optimization data. Time-resolved emission and transient absorption studies carried out on PDI-Tyr in the absence and presence of β-CD, revealed an excited state intramolecular charge transfer (ICT) process from the tyrosine moiety to the PDI core with a time constant of ~30 ps, and the same gets retarded on encapsulation of the tyrosine groups in the βCD:PDI-Tyr (2:1) complex and the kinetics slows down to ~480ps, reviving the emissive features. The absence of a long lifetime component and the lower emission enhancement in the monomeric condition as compared to the phenyl alanine (PDI-Phe) derivative, emphasizes the major role of the ICT process in PDI-Tyr, which subdue the features of intermolecular aggregation, establishing the tunability of the emissive properties with the customization of intra and intermolecular interactions.

Mean time to failure of a k-out-of-n system with a single cold standby unit having dependent components

. In this article, we consider a k-out-of-n system which is equipped with a single cold standby component. We assume that the components within the k-out-of-n system are exchangeable. The standby component becomes active when the k-out-of-n system experiences a failure. The active cold standby component reboots the system in collaboration with the remaining original active components. The dependency between the residual lifetimes of the survival components and the cold standby component is assumed to be modeled by a copula function C *, while the dependency between the original components of the k-out-of-n system is assumed to be modeled by a symmetric copula function C. Initially, we derive the common cumulative distribution function of the survival components of the k-out-of-n system at the time of the failure of the k-out-of-n system. After that, we compute the mean time to failure of the considered system. We analyze how various dependence parameters among the components impact the system’s reliability.

Barlow and Proschan principle for coherent systems with statistically dependent component and redundancy lifetimes

For coherent systems with components and active redundancies having heterogeneous and dependent lifetimes, we prove that the lifetime of system with redundancy at component level is stochastically larger than that with redundancy at system level. In particular, in the setting of homogeneous components and redundancy lifetimes linked by an Archimedean survival copula, we develop sufficient conditions for the reversed hazard rate order, the hazard rate order and the likelihood ratio order between two system lifetimes, respectively. The present results substantially generalize some related results in the literature. Several numerical examples are presented to illustrate the findings as well.

Reliability analysis of phased mission systems based on generalized stochastic Petri nets under mixed uncertainty

Phased mission systems (PMS) are widely applied across diverse industrial systems. Technological advancements in these systems have markedly improved their performance. However, fault characteristics such as uncertainty and common cause failure (CCF) frequently emerge during failures, which significantly raises new challenges in reliability analysis. A novel system reliability analysis framework is proposed to address the mixed uncertainty and CCF in PMS. Specifically, a hybrid modeling approach that combines dynamic fault trees and generalized stochastic Petri nets (GSPN) is employed to accurately model PMS containing CCF. This approach integrates predicates and assertions from GSPN to define four reusable sub-Petri net models at different hierarchical levels, including module, phase, CCF, and overall mission levels. Furthermore, interval theory is incorporated into the framework to manage imprecise component lifetime data. For uncertainty quantification, a synergistic approach combining genetic algorithm and Monte Carlo simulation is utilized. Additionally, a simplified approach is introduced to reduce the complexity of computing the reliability boundary values of PMS. Finally, the proposed method is applied to conduct reliability analysis of a phased altitude and orbit control system. The analysis results validate its effectiveness and applicability in addressing the mixed uncertainty and CCF of PMS.

Photoelectrical properties and excited-state dynamics of a nitrostilbene-functionalized organosiloxane liquid crystal

This study investigates the photophysical and electrical properties of 4-heptamethyl-trisiloxanyl-n-undecyloxy-4′-nitrostilbene (SNS), a low molar mass organosiloxane liquid crystal containing a nitrostilbene chromophore. Real-time monitoring of the absorption and fluorescence spectra of the nitrostilbene moiety was conducted in dichloromethane solution and thin films (in both crystalline and Smectic C (SmC) phases). A charge transfer excited state is formed following vibrational cooling and solvent interaction within 0.4 to 1.6 ps, which then relaxes to the ground state in 1.6 ns. Five distinct lifetime components were identified in thin films, attributed to the heterogeneous local environment and aggregate formation. Notable differences in excited-state lifetimes were observed between the crystalline and SmC phases, with slower dynamics in the former due to the rigidity of the crystalline phase. Photoconductivity under UV irradiation was examined in SmC, Smectic A (SmA), and isotropic phases, showing a significant increase in current response, particularly in the SmC phase. Polarizing optical microscopy revealed morphological changes post-UV exposure, such as reduced SmC domain size and decreased birefringence. Dielectric measurements indicated distinct relaxation peaks in SmC and SmA phases, reflecting more disordered molecular arrangements. The study reveals that UV exposure significantly enhances SNS conductivity, particularly within the SmC phase. This enhancement is likely attributed to UV excitation promoting the formation of an intramolecular charge transfer state within the trans-stilbene moiety. These findings provide valuable insights into the potential applications of nitrostilbene-functionalized organosiloxane liquid crystals in optoelectronic devices, such as light switches and photodetectors.

Stochastic Comparisons for Series and Parallel Systems with Heterogeneous Power Lomax Component Lifetimes

Stochastic Comparisons for Series and Parallel Systems with Heterogeneous Power Lomax Component Lifetimes

ANALISIS PERBAIKAN TAKE UP MOTION PROCESS PADA MESIN TENUN AIR JET LOOM DENGAN METODE FMEA

Take up motion is a crucial problem in the loom section because one of the core motions of the machine process. There were 67 process failures on the take up motion for three months. The study aims to decrease process failure on the take up motion which impacts on production loss, i.e down time and defects by applying FMEA. After analyzing the flow process, 11 potential causes were found from 3 potential failure modes in the areas. The first priority with RPN value of 108 is the quality of the roll teeth gear is not up to standard. Improvement recommendation is replacing the lower roll gear from plastic material to steel to increase component lifetime and performance. The Second priority with RPN value of 105 is the operator accuracy in installing the fabric roll at the beginning of the process. Improvement recommendation is implementing double checking procedures with inspection by supervisor. The Second priority with RPN value of 105 is the operator accuracy in installing the fabric roll at the beginning of the process. Improvement recommendation is implementing double checking procedures with inspection by supervisor. The third priority with RPN value of 96 is improper lubrication. Improvement recommendation is replacing the oil lubricant with grease which is appropriate for the engine speed. This research can recommend an improvement on take up motion based on the proposed repairs or maintenance list, using the FMEA method to decrease the process failure loom machine in the weaving industry.

Electrochemical Study of the Hot Corrosion Behavior of TP347H in Coal Ash

To maximize the effectiveness and efficiency of regular maintenances, it is crucial to predict the lifetime of critical components in coal-fired power plant by understanding the corrosion behavior of alloys in coal ash with varying thickness due to the continuous deposition and under different temperatures. This study explores the hot corrosion behavior of TP347H, which is a material commonly used as superheaters, in coal ash of varying thickness and at different temperatures. Through the use of electrochemical techniques such as open circuit potential (OCP), electrochemical noise, and potentiodynamic polarization (PDP), this study demonstrates a bell-shaped variation in the corrosion rate of TP347H between 650°C and 750°C. Furthermore, it was found that an increase in the thickness of coal ash significantly accelerates the kinetic processes involved in corrosion.

Observation of Nonlinear Emission Dynamics in a Quasi-Two-Dimensional Perovskite Crystal By Femtosecond Transient Absorption Microscopy

INTRODUCTION The phenomenon of superfluorescence using photoexcitation followed by induced synchronization of the dipoles is important not only from the fundamental viewpoint of understanding the interaction between light and matter but also from the applied viewpoint of realizing the miniaturization of light sources. Organic-inorganic lead halide perovskite materials have various attractive properties not only for solar cells but also for LED and nanoscale lasers because of their wavelength tunability and low lasing threshold. Such an efficient lasing is indispensable for their applications, and the essential needs are miniaturization and low threshold, especially for quasi-2D systems[1]. In this study, we aim to fabricate quasi-two-dimensional perovskite crystals and observe superfluorescence phenomenon by transient absorption microscopy. EXPERIMENTAL SECTION 110 mg of lead bromide, 70 mg of cesium bromide, and 24 mg of phenethyl ammonium bromide were dissolved in 3 mL of dimethyl sulfoxide and the solution was sealed in a spray vial under a nitrogen atmosphere. Then spray was applied onto a cover glass under a nitrogen atmosphere, and crystals were allowed to grow under isopropanol vapor for 8 min at 50°C.Transient absorption microscopy setup was the system previously reported[2]. A regenerative amplified Ti: sapphire laser (Solstice, Spectra-Physics, 1 kHz, 795 nm, output power about 3.5 W) was a light source. The 795 nm fundamental beam output from the regenerative amplifier was then split into two equal intensities by a beam splitter, and output light was obtained from an optical parametric amplifier (OPA, TOPAS, light-conversion). The signal light (1.3 μm) guided from OPA was directed onto an amorphous CaF2 plate to generate white light. This white light was divided into two parts by a half-mirror. A portion of the white light was transmitted to the sample on the microscope as the monitoring light. And the other part was used as the reference light. Both the monitoring and reference lights were guided into a multichannel spectrometer (Orca quest) for spectral analysis. The reference light is to correct the intensity fluctuation of the white light. Excitation light was generated from a home-built non-collinear OPA (NOPA) at 550 nm and introduced to the microscope. The temporal resolution was ca. 150 fs. RESULTS AND DISCUSSION The excitation light intensity dependence of the emission spectrum of a quasi-two-dimensional perovskite crystal was measured with a femtosecond 400 nm excitation. A new emission maximum is observed above 173 mJ/cm2. To clarify the origin of this emission, the femtosecond transient absorption spectrum was measured (Exc. 400 nm). The time profiles of transient absorbance at 526 nm show a positive signal in the early stage and a negative signal over 1 ps in a single quasi-two-dimensional perovskite crystal. The positive signal suggests the photoinduced absorption of the carrier in a few layers of two-dimensional perovskite. The negative signal suggests the bleaching and stimulated emission signal of perovskite in bulk. Hence, these changes from positive to negative signals indicate the energy transfer from a few layers to bulk. Fast decay components of stimulated emission were changed by changing the intensity of excitation pulses. To analyze the decay components of stimulated emission, global analysis was done for each time profile. Fig. shows the excitation intensity dependence of the lifetime of the stimulated emission. The initial lifetime component was related to the excitation light intensity by 1/N. These behaviors show the same dependence on excitation light intensity as the superfluorescence phenomena observed in time-resolved luminescence measurements[1]. We will discuss the spectrum evolution and relationship between energy transfer and superfluorescence at the conference site.REFERENCES[1] M. Biliroglu, K. Gundogdu et al., Nature photonics, 2022, 16, 324-329.[2] T. Katayama, A. Furube et al., Jpn. J. Appl. Phys., 2023, 62(SG), SG1030. Figure 1

Scheimpflug LIDAR for Gas Sensing at Elevated Temperatures.

Localized operating conditions inside boilers, heat recovery steam generators, or other large thermal systems have a huge impact on the efficiency, environmental performance, and lifetime of components. It is extremely difficult to measure species accurately within these systems due to the high temperatures and harsh environments, locally oxidizing or reducing atmospheres, ash, other particulates, and other damaging chemical species. Physical probes quickly suffer damage and are rendered nonfunctional. This work has attempted to adapt the measurement approach based on Scheimpflug light detection and ranging (S-LIDAR) for the remote sensing of gas species inside the high-temperature boiler environment. For a proof-of-concept, the detection of Raman signals of N2, O2, and CO2 and their behavior with increasing temperature have been presented.

Modeling nuclear power plant piping reliability by coupling a human reliability analysis-based maintenance model with a physical degradation model

Reliability and availability analysis for repairable components, considering the underlying physical degradation and maintenance, is crucial in support of risk assessment and management. In nuclear power plants (NPPs), reactor coolant piping is a representative example of safety-critical repairable components that are subjected to long-term physical degradation interacting with maintenance activities. The existing methods for piping reliability analysis suffer from a limitation in their capability to analyze the time-dependent physics-maintenance interactions that could occur during the component lifetime and alter the underlying maintenance processes, for instance, an enhancement of maintenance programs based on condition monitoring data or an observed defect. To address this limitation, this paper develops a new piping reliability analysis methodology that couples a physics-of-failure (PoF) model with a maintenance performance analysis model. The contributions of this paper are two-fold: (i) developing a human reliability analysis (HRA)-based maintenance performance analysis model for NPP piping that can quantify maintenance outcomes under multiple types of maintenance programs, including time-based and condition-based preventive maintenance; and (ii) developing a computational methodology to couple the HRA-based maintenance performance analysis model with PoF models. The proposed physics-maintenance coupling methodology is applied to an NPP piping case study.

Enhanced creep lifetime in P91 steel weldments via stabilizing tempered martensite structure

P91 steel weldments are susceptible to Type IV creep cracking during high-temperature service, significantly reducing the creep lifetime of impacted components. For enhancing the creep lifetime of P91 steel weldments, the present work proposes a novel post-weld heat treatment strategy to stabilize the tempered martensite structure and avoid Type IV creep cracking. Compared to conventional post-weld tempered treatment weldments, the creep lifetime of as-welded weldment is improved by 1.7 times, while the creep lifetime of weldment subjected to post-weld normalizing followed by tempering is enhanced by 4.6 times, effectively preventing Type IV cracking. It has been revealed that creep weakness zones, that is, soft zones, occur in as-welded weldment and post-welded tempering treatment weldment, where the microstructure is predominantly recrystallized ferrites. Creep fracture always occurs in the region of the highest fraction of recrystallized grains. Post-weld normalizing and subsequent tempering can enhance prior austenite grain size and stabilize tempered martensite structure. For as-welded weldment and post-welded tempering treatment weldment, creep cavities preferentially grow along ferrite grain boundaries as compared to prior austenite grain boundaries, which could easily lead to intergranular premature cracking. For post-weld normalizing and subsequent tempering weldment, cavities form along prior austenite grain boundaries of base metal and are elongated together with martensitic packets/blocks under stress. Finally, the final fracture is caused by the rupture of elongated grains.

The infrared thermography system on the MAST-U tokamak

Power loading from plasma in the scrape-off layer limits the lifetime of plasma-facing components in tokamak-based power plants. The Mega Ampere Spherical Tokamak Upgrade [W. Morris et al., IEEE Trans. Plasma Sci. 46(5), 1217–1226 (2018)] (MAST-U) features four divertor strike points (SP) owing to its up-down symmetry. This paper introduces the five-camera infrared thermography system, covering all four SPs and their mode of operation on MAST-U. The system employs both medium and long wavelength cameras, offering high frame rates up to 4 kHz and spatial resolutions of down to 3 mm. Postprocessing involves artifact elimination and heat flux calculation using in-house analysis software that incorporates the inverse heat transfer code, THEODOR (THermal Energy Onto DivertOR).

Repair of heat load damaged plasma–facing material using the wire-based laser metal deposition process

Due to its unique properties tungsten is a promising candidate as plasma-facing-material (PFM) in future nuclear fusion reactors. Tungsten features an exceptionally high melting point, high thermal conductivity, low tritium inventory and comparatively low erosion rate under plasma loading [1]. But given the extreme loads on the PFM during operation of a fusion reactor, the lifetime of plasma-facing components (PFC)s is limited. Currently, it is planned to replace damaged PFCs when they reach the end of their service life. However, the lifetime of PFCs could be increased by in situ repair using additive manufacturing technology (AM) in the form of direct-energy-deposition (DED). The wire–based laser metal deposition process (LMD-w) meets several necessary conditions for operation in the vessel and could be used for performing such in situ repairs.It was investigated if the LMD-w process is able to heal thermal induced surface cracks and roughening by remelting the substrate during deposition of tungsten. For this purpose, tungsten samples of 12 × 12 × 5mm3, which later served as substrate plates for the LMD-w experiments, were treated with combined steady-state and transient thermal loads in the electron beam facility JUDITH 2. These samples were brazed to a copper cooling structure and exposed to 105 thermal shocks of 0.5 ms duration and an intensity of Labs = 0.55 GW m−2 (FHF = 12 MW s0.5 m−2) at a base temperature of Tbase = 700 °C. This way, edge localized mode (ELM) like thermal load damage was induced on the tungsten samples. On these samples, different LMD-w and laser remelting process strategies were performed. Subsequently, these samples were analyzed, and it was examined that the healing of the pre-damaged substrate material was successful. In parallel, the laser remelting process was modeled in a thermal transient finite element method(FEM) simulation in order to gain an insight into the temperatures prevailing in the material during the process.

Investigating the exciton dynamics in InGaN/GaN core-shell nanorods using time-resolved cathodoluminescence.

This study examines the exciton dynamics in InGaN/GaN core-shell nanorods using time-resolved cathodoluminescence (TRCL), which provides nanometer-scale lateral spatial and tens of picoseconds temporal resolutions. The focus is on thick (>20 nm) InGaN layers on the non-polar, semi-polar and polar InGaN facets, which are accessible for study due to the unique nanorod geometry. Spectrally integrated TRCL decay transients reveal distinct recombination behaviours across these facets, indicating varied exciton lifetimes. By extracting fast and slow lifetime components and observing their temperature trends along with those of the integrated and peak intensity, the differences in behaviour were linked to variations in point defect density and the degree and density of localisation centres in the different regions. Further analysis shows that the non-polar and polar regions demonstrate increasing lifetimes with decreasing emission energy, attributed to an increase in the depth of localisation. The semi-polar facet instead showed a spectral independence of the lifetime which could not be rationalised by an absence of exciton localisation. This investigation provides insights into the intricate exciton dynamics in InGaN/GaN nanorods, offering valuable information for the design and development of optoelectronic devices.

Data-driven evaluation of the Paris’ law parameters in polyethylene pipe grades — Increasing the precision of fracture mechanical lifetime estimation

The Paris’ Law parameters A and m are a necessity for predicting lifetimes of structural components under static or fatigue loading that fail due to crack initiation and propagation. Conventional methods require measurements of crack growth kinetics that involve direct or indirect monitoring of physical crack extension during long-term experiments. Usually, measurement series also involve multiple specimens in order to obtain a crack growth controlled failure diagram of an investigated material under relevant load conditions. In this contribution a combination of simple numerical, statistical and analytical approaches is presented to obtain A and m without the need to measure actual crack growth. This is accomplished by reformulating the Paris’ Law to express A as a function of m. The parameter m is varied within a reasonable range to generate an analytical function for A that solves the equation of the Paris’ Law based lifetime for a single specimen. A subsequent superposition of all available specimens reveals an intersection of all A functions at the technically relevant pair of A and m values that are capable of describing the lifetime of all specimens with a minimum error. The obtained best-fitting A and m are in good agreement with literature and are able to predict the lifetime of previously published sample data based upon cyclic Cracked Round Bar test results with an average error of 3.30 ± 2.67%.

Understanding Environmental Barrier Coating Lifetimes and Performance for Industrial Gas Turbines

Abstract Hydrogen or hydrogen blend fuels are expected to replace natural gas in land-based industrial gas turbines (IGTs) to support a greener power economy. Silicon carbide (SiC) base ceramic matrix composites (CMCs) are considered for replacement of Ni-based superalloys to facilitate future efficiency improvements. SiC CMCs require environmental barrier coatings (EBCs) to mitigate volatilization from high-temperature steam, thus making the EBC lifetime critical information for identifying CMC component lifetimes. The goal of this project is to determine the maximum bond coating temperature underneath the EBC for achieving an IGT component lifetime goal of 25,000 h, which is far greater than current CMC component lifetime requirements for aeroturbine applications. To provide data for the lifetime model, laboratory testing used atmospheric plasma-sprayed rare-earth silicate EBCs on monolithic SiC substrates with an intermediate Si bond coating. Specimens exposed to 1-h thermal cycles in flowing air–steam environments and reaction kinetics were assessed from 700 °C to 1350 °C by measuring the thickness of the thermally grown silica scales. The silica growth and phase transformation appear critical in predicting EBC lifetime and several strategies have been explored to reduce the oxide growth rate and improve EBC durability at elevated temperatures. Advanced characterization using Raman spectroscopy has helped clarify this system.

Intramolecular benzene excimer formation in 13,14-diphenyldibenzo[b,j][4,7]phenanthroline.

13,14-diphenyldibenzo[b,j][4,7]phenanthroline (DBP3) in various solvents was studied by time-resolved fluorescence and fs transient absorption (fs-TA) spectroscopy. An intramolecular benzene excimer is demonstrated to form within DBP3; it exhibits strong redshifted emission with maximum at 540-640nm. "Intrinsic" fluorescence from DBP3 is dramatically quenched down to τ = 50-400fs in all the solvents studied. Fs-TA and time-resolved fluorescence spectra have proved that relaxed intramolecular benzene excimer is formed from S1 state via hot excimer state with three lifetime components: 50fs, ∼3.5ps, and ∼25ps, which are of the inertial (electronic) and diffusive parts of the relaxation due to solute-solvent interaction. Formation of triplet states via intersystem crossing was observed directly from the upper excited electronic states of DBP3.