Degradation Modes Research Articles

Local Interconnection Degradation of a Double-Sided Cooling SiC MOSFET Module Under Power Cycling

Local Interconnection Degradation of a Double-Sided Cooling SiC MOSFET Module Under Power Cycling

Innovative cooling technique to improve the performance of photovoltaic panels

The working performance of solar photovoltaic panels is affected by several factors. Accumulated dust and elevated temperatures from higher solar irradiance are the main factors. Therefore, a novel dual-cooling approach was employed, and its effect on the solar photovoltaic panels’ performance was investigated. The working front and backside temperatures, output power, and efficiency of the cooled solar photovoltaic panel were evaluated and compared. The results revealed that the current cooling process reduced the front and backside temperatures of the module by 22–45% and 34–47%, respectively, as compared with the dusty solar photovoltaic module. In the cooled photovoltaic module, the output current was higher by 26–48% and 4–5% compared with dusty and controlled modules, respectively, while the output voltage was found to be higher by 8–10% compared with the controlled and dusty modules. This led to a rise in output power for the cooled photovoltaic module by 22–51% and 8–13% compared to dusty and controlled modules throughout the day. In addition, the presence of dust on the photovoltaic module significantly reduces the overall efficiency to 11% compared to 17% when applying the cooling process. The levelized cost of electricity from the current cooled system was lower by 38.5% and 8% than in the dusty and uncooled systems, respectively. This means the proposed cooling system is efficient from an economic point of view. The results showed the distinct importance of the current dual-cooling process to avoid photovoltaic module degradation by accumulated dust and elevated temperatures.

The experimental study of the kinetics and modes of polymethyl methacrylate thermal degradation in argon flows

The experimental study of the kinetics and modes of the thermal degradation of polymethyl methacrylate (PMMA) in an argon flow was carried out. During thermogravimetric analysis the sample heating rates were 2, 5, 8, 20 and 35 K/min. Based on the integral isoconversional method the values of the kinetic rate constants of the PMMA thermal degradation were determined. When modeling the decomposition process of PMMA for low conversion degrees, it is advisable to use the reaction rate constant obtained for the conversion degree equal to 20 %, and for modeling the whole process – 50 %. Therefore, for evaluation calculations, it is possible to describe the process of PMMA decomposition with one gross reaction. Also, the investigation of the thermal degradation of PMMA particles under conductive heating conditions (680, 700, 720 K) in an argon and air was carried out. Based on the analysis of the data obtained, a scheme for the decomposition of PMMA, consisting of four stages, was established.

Comparative study of thermodynamic & kinetic parameters measuring techniques in lithium-ion batteries

Quantitative analysis of the aging process of lithium-ion batteries by using electrochemical thermodynamic and kinetic parameters such as electrochemical potential, Li stoichiometry, and Li inventory loss is a key research topic in the development of Li-ion battery for electric vehicles and smart grids. It is generally known the above parameters can be acquired through the analysis of Electromotive Force (EMF) or Open-Circuit Voltage (OCV) curves. In this work, we proposed and applied five EMF measurement techniques to obtain the EMF-SoC relationships in LFP/Gr single-layer laminated pouch cells at different temperatures and States of Health (SoH), and comprehensively examined them from the viewpoints of eight evaluation dimensions. A Python program, named Degradation Modes Analysis (DMA), is used to diagnose the thermodynamic degradation modes of the battery automatically. Furthermore, electrochemical kinetic parameters were also extracted along with the depolarization process. For faster and more accurate aging diagnosis, we recommend an optimal blend of short relaxation time GITT (Short-Rest-GITT) and extrapolated EMF (Extrap-EMF) to reach the most precise EMF measurements and gain the most comprehensive information about battery thermodynamics and kinetics at the same time.

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.

Predicting the lifetime of HJT modules towards the outdoor real-world environment

The high-performance silicon solar cells can be manufactured with the unique amorphous/crystalline heterojunction (HJT) structure. In the field applications of the photovoltaics, the durability of HJT modules has become an issue which gets a lot of attention. In this work, it was found that the ultraviolet-induced (UV-induced) degradation is largely caused by the decrease in short-circuit current, and UV cut-off polyolefin elastomers (POE) can effectively suppress the attenuation rate. Additionally, temperature and humidity also affect the module degradation rate, which was revealed through a series of damp-heat (DH) acceleration tests. From the analytical calculations of the data of UV and DH tests, Arrhenius activation energy of 0.43 eV was successfully derived. Accordingly, the Peck model was applied, which indicates that the lifetime of HJT modules can be predicted in the case of the specific climate parameters, such as temperature, humidity and UV irradiation. Based on this model, lifetime of HJT modules is around 22 years due to its stronger annual UV irradiation of over 72 kWh/m2 and over 80 % relative humidity (RH) in Hainan. By contrast, fortunately, lifetime of over 30 years is predicted at the lower UV irradiation of 48 kWh/m2 in Daqing and lower humidity of less than 55%RH in Ningxia, which are the typical photovoltaic climate zones of China.

Fatty acid degradation driven by heat during ripening contributes to the formation of the “Keemun aroma”

Ripening refers to the process of chemical change during the refinement of Keemun black tea (KBT) and is crucial in the formation of Keemun Congou black tea’s quality. In this study, the aroma composition of KBT during the ripening was analyzed. Sensomics indicated that ripening strengthened the coconut and fatty aroma of KBT and contributed to the decrease of green aroma substances, resulting in a shift of the overall aroma type of KBT to an integrated aroma profile, which was consistent with sensory evaluation. Changes in fatty acid content and the results of in vitro addition simulation tests confirmed that heat causes highly degradation of fatty acids into fatty aroma volatiles, which is a key driver of the formation of “Keemun aroma” quality. This study revealed the mechanism behind the formation of KBT’s integrated “Keemun aroma” quality and the mode of thermal degradation of major fatty acids.

The effect of topological design on the degradation behavior of additively manufactured porous zinc alloy

The advent of additively manufactured biodegradable porous metals presents a transformative opportunity to meet the criteria of ideal bone substitutes. Precisely tailoring their degradation behavior constitutes a pivotal aspect of this endeavor. In this study, we investigated the effects of topological designs on the degradation profile of laser powder bed fusion (LPBF) Zn scaffolds under dynamic in vitro immersion tests. Specifically, four types of Zn-0.4Mn-0.2Mg scaffolds (beam-based: diamond, face center cubic; surface-based: gyroid, schwarz-P) were designed and fabricated. The degradation mechanism of the scaffolds was comprehensively evaluated using both experimental and simulation methods. The results illuminate the profound impact of structural design on the degradation properties of the Zn alloy scaffolds. The beam-based diamond and face center cubic scaffolds exhibited a degradation rate of 0.08–0.12 mm per year with a relatively uniform degradation mode under dynamic immersion. On the contrary, the surface-based gyroid and Schwarz-P scaffolds demonstrated a notably reduced degradation rate due to lower permeability. This restricted the diffusion of medium ions within the pores, culminating in the accumulation of degradation products and more severe localized degradation. This study underscores the potential of topological design as a compelling strategy for tailoring the degradation profile of additively manufactured biodegradable scaffolds, thereby advancing their suitability as bone substitutes.

Microstructure degradation and residual low cycle fatigue life of a serviced turbine blade

AbstractThis paper was attempted to investigate the microstructure degradation and low cycle fatigue (LCF) performance of a serviced K465 Ni‐based superalloy turbine blade. LCF tests were carried out with small‐scale plate specimens sampled from the blades. Relationship between residual LCF life and microstructure state was estimated. The results indicate that the coarsening of γ/γ′ phases was the most significant microstructure degradation mode for the serviced blades. Both the γ matrix width and the γ′ precipitate diameter increased with the increase of service duration, while the γ′ precipitate volume fraction slightly decreased. The most severe microstructure degradation occurred at the leading edge along the chord direction, particularly at 50–70 % airfoil spans. The residual LCF life exhibited an accelerated decrease characteristic as increases of microstructure degradation degree. The coarsened microstructure diminished shear resistance of the superalloy, which resulted in additional accumulated inelastic deformation and a corresponding reduction in LCF life.

From Performance Measurements to Molecular Level Characterization: Exploring the Differences between Ultraviolet and Damp Heat Weathering of Photovoltaics Modules

The degradation behaviors of the encapsulant and the imbedded additives significantly determine the reliability of solar modules. Nevertheless, a link between the degradation of the encapsulant, including the additive interactions, and the longevity of the overall module is rarely established until now. Herein, mini‐modules containing ethylene‐vinyl acetate copolymer (EVA) as encapsulant are subject to damp heat (DH) or ultraviolet (UV) weathering based on IEC 61215. Macroscopically, the degradation under both weathering types characterized by I–V measurements and electroluminescence (EL) measurements is diverging in dependence on the used stressor. Using electron paramagnetic resonance and orbitrap mass spectrometry, it is shown that deacetylation of the EVA occurs significantly for both types of weathering. In the case of DH, however, the mechanism of action of the UV stabilizer is hindered, so that strong encapsulant degradation is observed despite a lower energy input in comparison with UV. Furthermore, the produced acetic acid under DH weathering leads to the observed reduction in EL, an increase in series resistance, and, a reduction of the performance of the modules. The work carried out shows that the degradation of the solar modules is strongly dependent on the behavior of the UV stabilizer.

The design of an RGD in situ sustained delivery system utilizing scallop byssal protein through genetic engineering

Although bioactive peptides enhancing bone healing have demonstrated effectiveness in treating bone defects, in vivo instability poses a challenge to their clinical application. Currently reported peptide delivery systems do not meet the demands of bone tissue repair regarding stability and peptide release efficacy. Herein, the self-assembling recombinant chimeric protein (Sbp5–2RGD) is developed by genetic engineering with cell adhesion peptide RGD as the targeted peptide and a newly discovered scallop byssal-derived protein Sbp5–2 that can assemble into wet stable films as the structural domain. In vitro studies show that the Sbp5–2RGD film exhibits excellent extensibility and biocompatibility. In vitro and in vivo degradation experiments demonstrate that the film remains stable due to the layer-by-layer degradation mode, resulting in sustained delivery of RGD in situ for up to 4 weeks. Consequently, the film can effectively promote osteogenesis, which accelerates bone defect healing and the implants osseointegration. Cell-level studies further show that the film up-regulates the expression of genes and proteins (ALP, OCN, OSX, OPN, RUNX2, VEGF) associated with osteogenesis and angiogenesis. Overall, this novel protein film represents an intelligent platform for peptide immobilization, protection, and release through its self-assembly, dense structure, and degradation mode, providing a therapeutic strategy for bone repair.

OsATL32 ubiquitinates the reactive oxygen species-producing OsRac5-OsRbohB module to suppress rice immunity.

Ubiquitination-mediated protein degradation is integral to plant immunity, with E3 ubiquitin ligases acting as key factors in this process. Here, we report the functions of OsATL32, a plasma membrane-localized Arabidopsis Tóxicos En Levadura (ATL)-type E3 ubiquitin ligase, in rice (Oryza sativa) immunity and its associated regulatory network. We found that the expression of OsATL32 is downregulated in both compatible and incompatible interactions between rice and the rice blast fungus Magnaporthe oryzae. The OsATL32 protein level declines in response to infection by a compatible M. oryzae strain or to chitin treatment. OsATL32 negatively regulates rice resistance to blast and bacterial leaf blight diseases, as well as chitin-triggered immunity. Biochemical and genetic studies revealed that OsATL32 suppresses pathogen-induced reactive oxygen species (ROS) accumulation by mediating ubiquitination and degradation of the ROS-producing OsRac5-OsRbohB module, which enhances rice immunity against M. oryzae. The protein phosphatase PHOSPHATASE AND TENSIN HOMOLOG enhances rice blast resistance by dephosphorylating OsATL32 and promoting its degradation, preventing its negative effect on rice immunity. This study provides insights into the molecular mechanism by which the E3 ligase OsATL32 targets a ROS-producing module to undermine rice immunity.

Exceeding 50 000 Cycle Durability of Layered Hydroxide‐Based Hybrid Supercapacitor Through Scandium Doping‐Induced Superlong Activation Process

Layered double hydroxides (LDHs) are a class of promising cathode materials for supercapacitors. However, the bad cycling performance has always been the Achilles’ heel of LDHs‐based supercapacitors. In this contribution, a nonelectrochemical active element Scandium (Sc) is doped into NiCo‐LDHs to greatly improve the intrinsic cycling performance of active materials. The trimetallic NiCoSc‐LDHs exhibit an ultralong cycle lifespan with 40 000 charge–discharge cycles (exceeding 50 days) and a high specific capacity of 196 mAh g−1 (1695 F g−1). Sc doping greatly changes the degradation mode of NiCo‐LDHs from rapid decay in thousands of cycles to a two‐stage performance evolution, which consists of a superlong activation process of about 10 000 cycles and then extremely slow degradation. Moreover, Sc doping enhances the electrochemical activity of Ni3+, so as to not only avoid its Jahn–Teller distortion, but also perform as a structural stabilizer to alleviate the local strain of host layer. The assembled asymmetric supercapacitor delivers an ultralong cycling lifespan with 101% capacity retention even after 50 000 cycles. This work presents a new pathway to significantly improve the electrochemical performance, especially the cycling stability of LDH‐based electrodes for high‐performance supercapacitors.

Evaluation of the Fatigue Performance of Full-Depth Reclamation with Portland Cement Material Based on the Weibull Distribution Model

The full-depth reclamation with Portland cement (FDR-PC) technology embodies an environmentally friendly approach to solving the damage to old asphalt pavement. Fatigue failure emerges as the predominant mode of degradation for FDR-PC pavement. The fatigue characteristics of the full-depth reclamation with Portland cement cold recycled mixtures were evaluated through four-point bending tests. Three contents (4%, 5%, 6%) of cement and three base-to-surface ratios (10:0, 8:2, 6:4) were utilized. The fatigue equations were derived for the mixtures using a two-parameter Weibull distribution. The results indicate that all correlation coefficients of the Weibull distribution model surpass 0.88, effectively projecting the lifespan of FDR-PC. With increases in cement contents and base-to-surface ratios, the fatigue life of the mixture extends, though with an augmentation of stress sensitivity. Comparative analysis with the fatigue equation model parameters of the current Chinese specifications for the design of highway asphalt pavement reveals that mixtures with a 4% cement content and combinations of a 5% cement content with a low base-to-surface ratio meet the requirements for inorganic-binder-stabilized soil. Additionally, mixtures with a 5% cement content and a high base-to-surface ratio, along with those with a 6% cement content, fulfill the specifications for inorganic-binder-stabilized granular materials.

Garbage In [formula omitted] Garbage Out: Exploring GAN Resilience to Image Training Set Degradations

Generative Adversarial Networks (GANs) have received immense attention in recent years due to their ability to capture complex, high-dimensional data distributions without the need for extensive labeling. Since their conception in 2014, a wide array of GAN variants have been proposed featuring alternative architectures, optimizers, and loss functions with the goal of improving performance and training stability. This manuscript focuses on quantifying the resilience of a GAN architecture to specific modes of image degradation. We conduct systematic experimentation to empirically determine the effects of 10 fundamental image degradation modes, applied to the training image dataset, on the Fréchet inception distance (FID) of images generated by a conditional deep convolutional GAN (cDCGAN). We find that at the α=0.05 level, brightening, darkening, and blurring are statistically significantly more detrimental to the resulting GAN image quality than removing the degraded data completely, while other degradations are typically safe to keep in training datasets. Additionally, we find that in the case of randomized partial occlusion, the FID of the resulting GAN images approaches that of the degraded training set for increasing levels of occlusion, with the surprising result that GAN FID performance is equal to that of the training set at 75% degradation.

Prognostic model and failure mechanisms of steam generators in Sodium-Cooled fast reactors

This paper presents a prognostic model for sodium-cooled fast reactor (SFR) steam generators (SGs). The purpose of the model is to estimate the remaining useful life of SFR SGs and thus to support the decision-making of autonomous control. SFR SGs are of great interest for plant integrity due to their harsh operation environment. They operate at higher temperatures and higher coolant-to-steam pressure differences than those of current light water reactors (LWR). The severity of the SFR SG failure consequences, which include water-sodium contact, is another reason. Understanding its failure mechanisms is important for the development of its prognostic model. Based on our literature review and physics-based analysis, we concluded that creep would be a dominant degradation mode of SFR SGs due to SFR’s high-temperature and high-pressure environment. Thus, creep is the focus of the prognostic model. Various other failure modes were also investigated in this study. The mechanical fatigue due to flow-induced vibration is usually observed in early developmental phases and would not be an important issue during normal operation. The thermal fatigue due to thermal stripping is occasionally observed in other components in SFRs but does not affect SG integrity. Pure water stress corrosive crack, fretting, and so on are commonly observed in LWR SGs but are significantly less important in SFR SGs because of the high temperatures, high pressure differences, and chemical properties of liquid sodium. Based on these investigations, a prognostic model focusing on creep failures was developed. It estimates the failure probability profile by sampling the Larson-Miller parameter (LMP) and temperature and associated uncertainties through Monte Carlo methods. Two case studies were presented. The first one demonstrated the model’s capability to calculate the failure probability for a new specimen within a given time. If the tube is working under temperatures of 500C ± 3 and pressures of 15.2 MPa, which leads to LMP of 20,100 ± 50, the failure probabilities within 50, 70, and 90 years are approximately 0.1 %, 3.2 %, and 17.5 %. The second demonstrated how adjusting the workload can help to protect the integrity of the component. For an old tube reaching 99 % of its lifespan, continuing to run at temperatures of 500C ± 3 and LMP of 20,100 ± 50 leads to a failure probability of about 29.0 % within a year. If the temperature is reduced by 5C, the failure probability can be reduced to 2.5 %, and, if the pressure is also reduced such that the LMP is increased by 100, the failure probability can further be reduced to 0.12 %.

Challenges of Predicting Temperature Dependent Capacity Loss Using the Example of NMC-LMO Lithium-Ion Battery Cells

In semi-empirical aging modeling of lithium ion-batteries an Arrhenius approach is commonly applied to describe the temperature dependency of a linear capacity loss. However, this dependency can change with degradation modes which was also observed in this cyclic aging study on NMC111-LMO graphite pouch cells in a temperature range of 4 °C to 48 °C. By means of differential voltage analysis and post-mortem analysis we correlated different regimes in capacity loss to degradation modes and aging mechanisms. In the first regime, a power dependency of time was observed. A second accelerated linear regime which followed an increase in loss of active material of the positive electrode was seen for medium (∼19 °C to 25 °C) to high aging temperatures. Transition metal dissolution was suggested to cause accelerated SEI growth. An activation energy could be estimated to 0.83 eV (± 0.17 eV, 95% CI). Finally, at aging temperatures around 45 °C we propose decreased charge transfer kinetics to result in mossy dendrites on the negative electrode which cause a final knee in aging trajectory. The findings highlight the necessity of sufficient aging temperatures and testing time.

Driving behavior-guided battery health monitoring for electric vehicles using extreme learning machine

An accurate estimation of the state of health (SOH) of batteries is critical to ensuring the safe and reliable operation of electric vehicles (EVs). Feature-based machine learning methods have exhibited enormous potential for rapidly and precisely monitoring battery health status. However, simultaneously using various health indicators (HIs) may weaken estimation performance due to feature redundancy. Furthermore, ignoring real-world driving behaviors can lead to inaccurate estimation results as some features are rarely accessible in practical scenarios. To address these issues, we proposed a feature-based machine learning pipeline for reliable battery health monitoring, enabled by evaluating the acquisition probability of features under real-world driving conditions. We first summarized and analyzed various individual HIs with mechanism-related interpretations, which provide insightful guidance on how these features relate to battery degradation modes. Moreover, all features were carefully evaluated and screened based on estimation accuracy and correlation analysis on three public experimental battery degradation datasets. Finally, the scenario-based feature fusion and acquisition probability-based practicality evaluation method construct a useful tool for feature extraction with consideration of driving behaviors. This work highlights the importance of balancing the performance and practicality of HIs during the development of feature-based battery health monitoring algorithms.

Pr doped La2Zr2O7 TBCs by EB-PVD: Thermal property, morphology and degradation mechanism

Pr doped La2Zr2O7 (LPZ) TBCs have been deposited by electron beam physical vapor deposition. This work concentrates on the thermophysical properties and microstructure evolution of LPZ/YSZ duplex TBCs before and after thermal cyclic so as to probe into the merit and the application feasibility. The thermal expansion, thermal conductivity and phase structure have been measured and analyzed in comparison to other classical TBCs materials. Typical feathery microstructure and intra-columnar gaps did not provide desired thermal cyclic counts for LPZ/YSZ TBCs. Two principal categories of degradation mechanism limited the cyclic lifetime. The first principal degradation mode is the pulverization of LPZ after thermal cyclic due to the Pr rare earth elements modification in lanthanum Zirconates. Pr instability created the pulverization degradation mode instead of spalling. The second degradation mode is the cracks extension paralleled to interface inside TGO due to the brittle spinel generated by excessive oxidation. This study of thermal properties and degradation mechanism might offer thought and inspiration for other advanced TBCs.

Degradation of warm permafrost and talik formation on the Qinghai‒Tibet Plateau in 2006–2021

Permafrost is degrading globally, particularly those with low thermal stability on the Qinghai‒Tibet Plateau, owing to climate change. However, the inadequacy of direct research on permafrost degradation based on in-situ monitoring limits the prediction of permafrost degradation and engineering practices. This study explored the processes and modes of permafrost degradation into talik by analyzing ground temperature data from five points in the hinterland of the Qinghai‒Tibet Plateau from 2006 to 2021. The results showed that the degradation of the warm permafrost layer with a geothermal gradient of zero occurred simultaneously in the top and bottom directions. The rate of permafrost degradation from the top down and bottom up increase during the degradation process, but the increase of the former is more drastic after the formation of thawed interlayer. Additionally, the construction of the Qinghai‒Tibet Railway changed the degradation modes of the permafrost in adjacent natural sites through horizontal heat transfer, particularly after through talik formation under the embankment. The findings suggest that taking countermeasures before or immediately after forming thawed interlayer is more effective. When evaluating the thermal impact of projects in warm permafrost regions, special attention should be given to the horizontal heat transfer process that may result from the formation of a through talik.