Degradation Phenomena Research Articles

Mechanical and Physical Changes in Bio-Polybutylene-Succinate Induced by UVC Ray Photodegradation.

Bio-polybutylene succinate (PBS) is a biodegradable polymer obtained from renewable feedstock having physical-mechanical properties like traditional low-density polyethylene (LDPE). PBS is employed by many manufacturing sectors, from biomedical to agri-food and cosmetics. Although some studies have already evaluated the resistance of PBS to photodegradation caused by natural outdoor solar exposure (UVA-UVB), a systematic study on the resistance to degradation caused by exposure to UVC rays, which is the subject of this study, has not yet been carried out. PBS was exposed to UVC either neat or filled with 2% carbon black (CB). Mechanical and physical characterization (tensile, hardness, calorimetry, contact angle, morphology, and surface roughness analyses) indicates that the bulk and surface properties of the polymer matrix changes after exposure to UVC radiations, due to a severe degradation. However, the presence of carbon black compensates for the degradation phenomenon. Because UVC rays are used for the sterilization process, necessary in applications such as biomedical, cosmetic, pharmaceutical, food, and other products, a comparison of the protocol used in this paper with the literature's data has been reported and discussed.

Physics-Informed Design of Hybrid Pulse Power Characterization Tests for Rechargeable Batteries

Industry-standard diagnostic methods for rechargeable batteries, such as hybrid pulse power characterization (HPPC) tests for hybrid electric vehicles, provide some indications of state of health (SoH), but lack a physical basis to guide protocol design and identify degradation mechanisms. We develop a physics-based theoretical framework for HPPC tests, which are able to accurately determine specific mechanisms for battery degradation in porous electrode simulations. We show that voltage pulses are generally preferable to current pulses, since voltage-resolved linearization more rapidly quantifies degradation without sacrificing accuracy or allowing significant state changes during the measurement. In addition, asymmetric amounts of information gain between charge /discharge pulses are found from differences in electrode kinetic scales. We demonstrate our approach of physics-informed HPPC on simulated Li-ion batteries with nickel-rich cathodes and graphite anodes. Multivariable optimization by physics-informed HPPC rapidly determines kinetic parameters that correlate with degradation phenomena at the anode, such as solid-electrolyte interphase (SEI) growth and lithium plating, as well as at the cathode, such as oxidation-induced cation disorder. If validated experimentally, standardized voltage protocols for HPPC tests could play a pivotal role in expediting battery SoH assessment and accelerating materials design by providing new electrochemical features for interpretable machine learning of battery degradation.

The Study and Improvement of Pressure Degradation of Helium Cryogenic System at NSRRC

This paper is aimed at studying and improving the phenomenon of pressure degradation in a helium cryogenic system. There are two 450W helium cryogenic systems for the Taiwan light source (TLS) and one 890W helium cryogenic system for the Taiwan photon source (TPS) housed at the National Synchrotron Radiation Research Center (NSRRC). The TLS helium cryogenic system is used for one superconducting radio frequency (SRF) cavity and five superconducting magnets. The TPS helium cryogenic system is used for two SRF cavities at the present stage. These three helium cryogenic systems have experienced pressure degradation, which reduced their performance and increased liquid nitrogen consumption for precooling over the past few years. A cryogenic adsorber was set up in an effort to capture the impurities, but this made no difference for pressure degradation in the system. The impurities were comprised of not only gas but also moisture. It was found that the cryogenic adsorber was not efficient enough to remove the moisture. This paper presents the study for the phenomena of pressure degradation. A moisture removal system was designed which is also discussed.

Remaining useful life prognostics during boiling-induced surface degradation

After sustaining long-term nucleate boiling, any surface is prone to changes over time, which signifies an important operational characteristic for reliable thermal management; however, recent research of this topic is extremely scarce. In this work, we first present long-term pool boiling experiments on samples of different surface topography and morphology in de-ionized water and in an aqueous salt solution. We show the changes induced by vigorous bubble nucleation over the course of several hundred hours of operation, discussing the underlying degradation phenomena. Following this, we present an adaptive data-driven prognostic approach, capable of estimating the remaining useful life (RUL) of a boiling surface in real time, based on change of surface temperature. The method consists of (i) a Kalman filter to identify the degradation drift model and (ii) a Monte Carlo simulation to propagate the drift to the terminal threshold, obtaining a distribution of predicted RUL values. Its practical applicability, validated on experimental results, is reinforced by its advantageous features of (i) prognostic performance not depending on the boiling surface or its degradation mechanisms, (ii) low computational demand and (iii) numerous options for individual tuning and extensions.

Ion-migration analysis of degradation caused by outdoor exposure and accelerated stress testing in perovskite solar cells

In this study, we conducted outdoor exposure testing and investigated the degradation mechanism of perovskite solar cells deployed in the field. We conducted a detailed failure analysis to identify specific degradation modes induced by outdoor exposure, using current–voltage curve measurements, maximum power evaluation, and mobile-ion analysis. This analysis revealed a significant change in the ion-migration current response of the devices after exposure. These changes suggest that the modification of mobile ions and formation of defects within the perovskite materials are likely the primary causes of degradation. Additionally, we compared the solar cell characteristics observed after the field test with the results of controlled indoor accelerated stress tests, which included exposure to visible light, ultraviolet (UV) irradiation, and thermal stress. Our findings highlight that the degradation patterns induced by UV irradiation at elevated temperatures closely resemble those caused by outdoor stress. We also discuss indoor test conditions that replicate the degradation phenomena experienced during outdoor exposure. This ability to replicate outdoor degradation phenomena under laboratory conditions is crucial for accelerating the development of robust and durable perovskite solar cells.

Energy management control strategies addressing the rSOC degradation phenomena in a polygeneration microgrid

Economically competitive long-term energy provision and performance stability are becoming increasingly strategic for the upcoming energy market. Despite hydrogen-based technologies representing a viable way for the aforementioned targets, such systems are affected by performance reduction over time. This paper is aimed at presenting energy management mitigation policies for a reversible solid oxide-based (rSOC) polygeneration microgrid. Particularly, interest has been paid towards the rSOC degradation phenomena and its mitigation by applying strategies allowing meeting target performance and satisfying economics. In a multilevel framework, the rSOC degradation mitigation has been pursued proposing two central-level strategies, namely Grid support (GS) and Limited Grid support (LGS), which act between the power split targets coming from the supervisory level and working set points actuated by the low-level controllers. The former aims at compensating for the energy gap caused by degradation relying on external contributions: power grid network and boilers. Alike, the goal of the latter is to keep the rSOC turned on as much as possible, therefore, complying with the energy management goals given by supervisory level. The state of charge of the hydrogen storage tank has been chosen as a metric to best show the results obtained implementing the mitigation strategies, as it directly displays the rSOC active management and boundaries applied on the storage systems. Considering a 3 years scenario, the LGS strategy in comparison to the GS one has resulted to be more effective concerning: costs, microgrid self-sufficiency, reliability and overall robustness. Quantitatively, for the LGS strategy, considering degradation degrees in the range 0.25–1 %/kh, relative additional integration costs with respect to the case unaffected by degradation are seen to be in the range 30–105 %.

Theoretical Understanding of Effects of Operating Modes on the Performance Durability of Solid Oxide Cells: A Comparison between Potentiostatic and Galvanostatic Operations

In solid oxide cells (SOCs), the choice between galvanostatic (constant current) and potentiostatic (constant voltage) modes does not significantly affect the performance of SOCs as long as the cell components remain unchanged and intact. However, the degradation of cell components, which leads to changes in electrochemical and physical properties of the cell, elevates the importance of the selected operating mode. This paper aims to investigate the effects of galvanostatic and potentiostatic operating modes on the evolving properties of SOCs and their subsequent influence on performance durability. Employing non-equilibrium thermodynamic analysis, a crucial approach for understanding the degradation phenomena within an active electrochemical system, this study aims to provide in-depth insights into how these operating modes affect the longevity and efficacy of SOCs. Key findings include: In cases where oxygen electrode (OE) degradation is accelerated by higher partial pressure of oxygen ( pO2 ), operating under constant voltage electrolysis can mitigate the high pO2 at the OE|electrolyte (OE|EL) interface. Conversely, if OE degradation occurs more rapidly under a lower pO2, constant current electrolysis is more effective in suppressing degradation by achieving a high pO2 at the OE|EL interface. For degradation of the fuel electrode (FE) due to higher pO2, constant current electrolysis is beneficial for more stable performance, which helps maintain low pO2 at the FE|EL interface. When FE degradation is accelerated by lower pO2, constant voltage electrolysis can avert low pO2 at the FE|EL interface. In practical scenarios, more complex degradation mechanisms come into play, especially when pO2 significantly deviates from initial conditions. Degradation in one electrode can influence pO2 in the other electrode, a phenomenon more pronounced in potentiostatic than in galvanostatic electrolysis.

Reliability evaluation method for PID feedback control system considering performance degradation

The reliability of proportional-integration-derivative (PID) feedback control systems is crucial for products due to their critical functions. Traditional reliability evaluation methods of PID feedback control systems usually pose difficulties in comprehensively considering the performance compensation property of feedback mechanisms and the degradation phenomenon in operating processes. This paper proposes a new reliability evaluation method for the PID control system under the framework of belief reliability theory to consider both deterministic and uncertain laws regarding functional logics and degradation effects. For deterministic laws, the interdisciplinary, degradation, and margin equations are established with respect to the steady state error. Various internal and external influencing factors are integrated into these equations by modeling state space and characterizing degradation mechanisms. For uncertain laws, the metric equation is constructed accordingly considering diverse uncertain factors. A Monte Carlo-based algorithm and an analysis framework are further developed to calculate the belief reliability. Finally, the proposed method is implemented to an aero-power hydraulic servo control system as a specific illustration, demonstrating its effectiveness and rationality.

RETRACTED: Integrating confidence calibration and adversarial robustness via adversarial calibration entropy

The vulnerability of deep neural networks to adversarial samples poses significant security concerns. Previous empirical analyses have shown that increasing adversarial robustness through adversarial training leads to models making unconfident decisions, undermining trust in model confidence scores as an accurate indication of their reliability. This raises the question: are adversarial robustness and confidence calibration mutually exclusive? In this work, we find empirically that adversarial examples mislead undefended models to make more confident mistakes during an attack and that adversarial training causes models to become more risk-averse. Further, we investigate the phenomenon of adversarial degradation from an uncertainty perspective and demonstrate that confidence and adversarial robustness can exhibit a uniform trend. To simultaneously improve the model's adversarial robustness and confidence calibration performance, we propose a novel adversarial calibration entropy to regularize the cross-entropy. Extensive experiments show that our approach increases the confidence that the model makes correct decisions and achieves adversarial robustness comparable to current state-of-the-art models.

Log‐location‐scale increment degradation model: A Bayesian perspective

AbstractDegradation modeling serves as a valuable tool for assessing the lifetime information of highly reliable products. One frequently employed approach for describing the degradation phenomenon involves the use of a degradation model that relies on stochastic processes. In a stochastic‐process‐based degradation model, it is assumed that the increments follow a distribution with the additivity property. This property makes the further inferences mathematically and statistically tractable. However, it limits the choices of the distributions. This paper aims to use those distributions without the additivity property to model the increments and explores distributions from the log‐location‐scale family. Under the frame of Bayesian analysis, Markov Chain Monte Carlo algorithms are developed for executing the necessary computations. Given that the proposed degradation models do not adhere to the additivity property, this paper tackles the challenges involved in predicting the lifetime of both on‐line and off‐line products. Two illustrative examples are subsequently analyzed to demonstrate the procedural steps outlined. The suitability of the proposed model is finally validated through a simulation study.

Comparative Analysis of the Effects of Incorporating Post-Industrial Recycled LLDPE and Post-Consumer PE in Films: Macrostructural and Microstructural Perspectives in the Packaging Industry.

In accordance with the Circular Economy Package of the European directive, the Spanish government compels manufacturers of plastic bags to include into their products a minimum of 70% of polyethylene (PE) waste. Following this mandate can be challenging and requires a deep knowledge of the alterations produced by the recycling in the main components of a plastic bag film: lineal low-density polyethylene (LLDPE), the LLDPE recycled post-industry, generated as waste from an industrial process (rLLDPE) and the PE recycled from post-consumer use (rPE), that has been picked up, cleaned, and reprocessed. This study provides insight in the macro and microstructural changes produced by several cycles of recycling in these materials. Specimens in the form of film for supermarket bags formed with these polymers have been subjected to several recycling sequences. The process closely mimics industrial processes. Four cycles have been applied to the samples. The evolution of mechanical properties, including tensile strength, elongation at break, and tear and impact tests, shows an obvious decrease due to degradation that is not an impediment for practical use after the four cycles of recycling according to the main specifications defined by the producer. Colorimetric measurements reveal no significant variations in the color of the films. The results of the FTIR and TGA analysis show degradation phenomena and changes in crystallinity in branching and the apparition of crosslinking that are in consonance with the mechanical data. There is also a difference between both types of recycled PE. In general, rLLDPE is more affected by the recycling than rPE. According to our findings, the limiting property would be the tearing. By comparing these values with bags available in the market, manufactured from 70-80% recycled material, we can infer that while two reprocessing cycles can lead to good results, a maximum of four cycles of recycling is advisable.

A deep multi-branch attention model for histopathological breast cancer image classification

Since the impressive superior performance demonstrated by deep learning methods is widely used in histopathological image analysis and diagnosis, existing work cannot fully extract the information in the breast cancer images due to the limited high resolution of histopathological images. In this study, we construct a novel intermediate layer structure that fully extracts feature information and name it DMBANet, which can extract as much feature information as possible from the input image by up-dimensioning the intermediate convolutional layers to improve the performance of the network. Furthermore, we employ the depth-separable convolution method on the Spindle Structure by decoupling the intermediate convolutional layers and convolving them separately, to significantly reduce the number of parameters and computation of the Spindle Structure and improve the overall network operation speed. We also design the Spindle Structure as a multi-branch model and add different attention mechanisms to different branches. Spindle Structure can effectively improve the performance of the network, the branches with added attention can extract richer and more focused feature information, and the branch with residual connections can minimize the degradation phenomenon in our network and speed up network optimization. The comprehensive experiment shows the superior performance of DMBANet compared to the state-of-the-art method, achieving about 98% classification accuracy, which is better than existing methods. The code is available at https://github.com/Nagi-Dr/DMBANet-main.

Photoelectrochemical, all-soluble iron redox-flow battery for the direct conversion of solar energy

A photoelectrochemical redox-flow battery (RFB) employing an all-soluble, aqueous coordination chemistry of the element iron is developed. The system is based on the ferro/ferricyanide redox couple as posolyte, the iron-triethanolamine (TEOA) complex as negolyte and a Ge/GaAs/GaInP triple-junction solar cell (TJSC) as power source. Combining a discharging flow-cell with the photoelectrochemical unit, we enable an operando monitoring of degradation phenomena at the working electrode similar to a rotating ring-disc electrode (RRDE). In this manner, an irreversible deactivation of an unprotected TJSC is observed after 15 h of operation. In a post-mortem SEM/EDX analysis, this performance loss is identified to result from a dissolution of the top junctions of the photoabsorber. Mitigating this corrosion is achieved by introducing a 150 nm thick protection layer of TiO2 via reactive sputtering. In this manner, a stable performance for more than 120 h is obtained. In view of the fact that the iron species selected for this study are affordable, abundant, water-based and non-toxic our device is a prototype of a green photoelectrochemical RFB at laboratory scale.

Parametric outline of a centrifugal pump as an element complex thermodynamic system

The stability of the level of parameters of the working medium, which enters the combustion chamber of the heat engine, is realized due to the proper operation of all elements of the fuel supply system. The problems of selection, design and operation of one of the standard sizes of centrifugal pumps of fuel supply systems of heat engines are considered. On the basis of selected models of parameters of the first approximation, proposals are presented for computational and experimental studies of the outline. A method of mathematical consideration of the phenomenon of degradation of individual performance characteristics is proposed.

Performance of 4H–SiC radiation detector after high flux proton and Fe13+ heavy ion beam irradiation

A batch of Schottky diode 4H–SiC detectors was fabricated by using Ni/Au electrodes, which were irradiated by Fe13+ heavy ion beam current with a flux of 1 × 1013 n/cm2 to 4.35 × 1014 n/cm2 in a stepwise increment, the forward and reverse I–V characteristics before and after irradiation as well as the energy resolution of α particles produced by 241Am source were tested and compared. The test results show that the reverse leakage current of the 4H–SiC detector that we made after the radiation of Fe13+ heavy ion beam increases gradually with the increase of the irradiation flux, Schottky Barrier Height decreases continuously where the ideal factor gradually increases. When the flux is 4 × 1013 n/cm2, it has risen to 9 μA, but the detector still has an energy resolution of 2.63%. When the flux of Fe13+ heavy ion beam is increased to 8 × 1013 n/cm2, the very obvious degradation phenomenon appears, the Charge Collection Efficiency(CCE) is reduced from 100% to 66.08%, the energy resolution is changed from 1.6% to 4.33%. When flux is increased to 1.4 × 1014 n/cm2, and the detector's performance has degraded seriously, in which the energy resolution is decreased from 1.76% to 9.54%, meanwhile the CCE is reduced from 100% to 64.84%, but it can still be used. As the beam flux reaches 2 × 1014 n/cm2, the detector has been completely damaged. At the same time, the ability of the detector to be resist mixed ion beam irradiation was tested. The 4H–SiC detector still has an energy resolution of 2.51% after receiving a dose of irradiation, which concluded with 1 × 1017 n/cm2 protons and 2 × 1013 n/cm2 Fe13+ heavy ion beams.

Selective damage induced by pigment-medium interactions in a Neoplasticist oil canvas painting: Composition dans le cône avec couleur orange by G. Vantongerloo (1929)

This research focuses on the study of pigment-medium interactions in the film forming, ageing and degradation mechanisms of modern white oil paints observed in the Neoplasticist painting Composition dans le cône avec couleur orange by G. Vantongerloo (1929), conserved in the Institut Valencià d’Art Modern (IVAM). The observation of selective vertical cracks and the significant presence of protrusions in the painting suggested that the observed degradation phenomena were specific to the coloured area. To understand the composition of pigments governing the film formation processes and later degradation phenomena in the oil paint films, a hybrid experimental approach was taken, aimed at understanding the physical, chemical and mechanical mechanisms involved. For this purpose, digital portable microscopy and multiband imaging analyses were carried out. Furthermore, the technical study involved the use of micro-invasive analysis such as μ-Raman, ATR-FTIR spectroscopy and GC–MS analysis for a more comprehensive understanding of the nature of the binding media and products resulting from the auto-oxidation, film-forming, hydrolysis, and degradation processes of the lipidic binding media. The results obtained suggest that on-going degradation phenomena are closely linked to the chemical interaction between pigment and binding medium.

Spherical Gravity Forwarding of Global Discrete Grid Cells by Isoparametric Transformation

For regional or even global geophysical problems, the curvature of the geophysical model cannot be approximated as a plane, and its curvature must be considered. Tesseroids can fit the curvature, but their shapes vary from almost rectangular at the equator to almost triangular at the poles, i.e., degradation phenomena. Unlike other spherical discrete grids (e.g., square, triangular, and rhombic grids) that can fit the curvature, the Discrete Global Grid System (DGGS) grid can not only fit the curvature but also effectively avoid degradation phenomena at the poles. In addition, since it has only edge-adjacent grids, DGGS grids have consistent adjacency and excellent angular resolution. Hence, DGGS grids are the best choice for discretizing the sphere into cells with an approximate shape and continuous scale. Compared with the tesseroid, which has no analytical solution but has a well-defined integral limit, the DGGS cell (prisms obtained from DGGS grids) has neither an analytical solution nor a fixed integral limit. Therefore, based on the isoparametric transformation, the non-regular DGGS cell in the system coordinate system is transformed into the regular hexagonal prism in the local coordinate system, and the DGGS-based forwarding algorithm of the gravitational field is realized in the spherical coordinate system. Different coordinate systems have differences in the integral kernels of gravity fields. In the current literature, the forward modeling research of polyhedrons (the DGGS cell, which is a polyhedral cell) is mostly concentrated in the Cartesian coordinate system. Therefore, the reliability of the DGGS-based forwarding algorithm is verified using the tetrahedron-based forwarding algorithm and the tesseroid-based forwarding algorithm with tiny tesseroids. From the numerical results, it can be concluded that if the distance from observations to sources is too small, the corresponding gravity field forwarding results may also have ambiguous values. Therefore, the minimum distance is not recommended for practical applications.

Comparison of different frost models with hygrothermal simulations to better understand frost damage in porous building materials

Frost damage is one of the most important degradation phenomena of brick facades. Evaluating the risk of frost damage in advance is of utmost importance considering the difficulty of repairing frost damage without replacing the materials, which may not be an option for protected heritage facades. Various performance criteria and methods have been developed over the past decades to assess the risk of frost damage. However, these methods are derived from frost tests under extreme conditions, such as high saturation levels and very low freezing temperatures, and do not represent realistic conditions for mild climates. In 2019, Feng et al. tested four different bricks under milder conditions to understand the relationship of frost damage with freezing temperature and saturation degree. The research in this paper combines the results of Feng's study with hygrothermal simulations, which prove to be a valuable tool for assessing the risk of deterioration of facades of masonry buildings. In this paper, the frost decay assessment methods like the Fc-index, GC-factor and counting the critical freeze-thaw cycles are examined, discussed and finally dismissed. Finally, a more representative frost decay risk assessment method is proposed.

Oxygen Transport through Amorphous Cathode Coatings in Solid-State Batteries.

All solid-state batteries (SSBs) are considered the most promising path to enabling higher energy-density portable energy, while concurrently improving safety as compared to current liquid electrolyte solutions. However, the desire for high energy necessitates the choice of high-voltage cathodes, such as nickel-rich layered oxides, where degradation phenomena related to oxygen loss and structural densification at the cathode surface are known to significantly compromise the cycle and thermal stability. In this work, we show, for the first time, that even in an SSB, and when protected by an intact amorphous coating, the LiNi0.5Mn0.3Co0.2O2 (NMC532) surface transforms from a layered structure into a rocksalt-like structure after electrochemical cycling. The transformation of the surface structure of the Li3B11O18 (LBO)-coated NMC532 cathode in a thiophosphate-based solid-state cell is characterized by high-resolution complementary electron microscopy techniques and electron energy loss spectroscopy. Ab initio molecular dynamics corroborate facile transport of O2- in the LBO coating and in other typical coating materials. This work identifies that oxygen loss remains a formidable challenge and barrier to long-cycle life high-energy storage, even in SSBs with durable, amorphous cathode coatings, and directs attention to considering oxygen permeability as an important new design criteria for coating materials.

Investigation of 19th and early 20th century Prussian blue production methods and their influence on the pigment composition and properties

Several degradation phenomena, including cracking and paint loss have been observed in Prussian blue oil paint strokes in Vincent van Gogh's paintings. To understand the influence of the pigment on these phenomena, 19th and early 20th century preparation and purification methods of the Prussian blue pigment and their influence on its composition and properties were studied using contemporary sources. Recipes for replication were selected based on their prevalence, the detail in their description, as well as the quality ascribed to the prepared pigments. Two direct recipes, two indirect recipes, a conversion from soluble to insoluble Prussian blue and two 18th century recipes were used for the reproduction of Prussian blue, including the historical purification methods. The prepared pigments were analysed using ATR-FTIR, XRD and SEM-EDX. Differences between the pigments were found in the presence of certain contaminants, as well as in the size and shape of the pigment particles. These contaminants included nitrates and carbonates. The differences in particle characteristics were found to result in differences in shades and tinting strengths of the pigments and prepared oil paints.