Degradation Evaluation Method Research Articles

Degradation Adaptability Assessment of Semisolid Powder Molded Mg-Zn-Mn Alloys for Orthopedic Applications.

Semisolid powder molding was used to prepare the medical Mg-6Zn alloy; in order to further improve its degradation adaptability, 0.5 and 1 wt % Mn were added. Then, the effect of the forming temperature (540, 560, 580, and 600 °C) on the in vitro degradation behavior of the prepared Mg-6Zn-xMn (x = 0.5, 1 wt %) was analyzed, and the optimized alloy was obtained. Finally, the biocompatibility and in vivo degradation performance of the optimized and Mn-free alloys were evaluated. Importantly, single-photon emission tomographic imaging (SPECT/CT) was first applied to monitor the in vivo degradation process. The results show that the corrosion mechanism of the Mn-free alloy is microgalvanic corrosion control with corrosive pitting. After adding Mn, the in vitro degradation rate decreases by half (0.17 ± 0.01 mm/year) as the forming temperature increases to 600 °C, and Mg-6Zn-1Mn prepared at 600 °C is the optimized alloy. Mn addition improves the corrosion product film protection and discontinuous secondary phases, and thus, the corrosion mechanism is changed to corrosive pitting control. Additionally, semisolid powder molding is an easy method to prepare alloys with low average pore interconnectivity (<10%), which is helpful for slowing down the degradation rate. The Mn-containing alloy has better biocompatibility, with a cytotoxicity of grade 0-1, due to its lower degradation rate. The in vivo corrosion rate of the Mn-free alloy is 0.19 mm/year after 28 days of implantation, which was precisely detected by SPECT/CT in real-time. The long-term in vivo degradation adaptability of Mn-free and Mn-containing alloys was not correctly presented, which may be due to the unreasonable bone defect model causing implant displacement. However, both of these alloys cause no obvious inflammation and show good healing. In summary, semisolid powder molding is a potentially promising technique to prepare medical Mg alloys, and nuclear imaging is an effective in vivo degradation evaluation method.

Data-Driven Lithium-Ion Battery Degradation Evaluation Under Overcharge Cycling Conditions

Accurately assessing degradation and detecting abnormalities of overcharged lithium-ion batteries is critical to ensure the health and safe adoption of electric vehicles. This paper proposed a data-driven lithium-ion battery degradation evaluation framework. First, a multi-level overcharge cycling experiment was conducted. Second, the battery degradation behaviours and features were analyzed and extracted using incremental capacity analysis and pearson correlation coefficient. Above all, a data-driven lithium-ion battery degradation evaluation method based on machine learning and model integration method was developed. The proposed integrated model was compared with other state-of-the-art methods and reached a mean squared error of 1.26×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> . Finally, based on prediction results, rate of degradation was calculated and classified to different degrees, and overcharged cells can be effectively identified. Moreover, to verify the feasibility of the proposed overall framework, the paper carried out an experiment by connecting overcharge-induced degraded cell and fresh cells in series to simulate the real-world battery assembly and function of battery management systems. Based on the proposed scheme, the overcharged batteries in the battery series can be detected efficiently likewise.

Improved degradability and mechanical properties of bacterial cellulose grafted with PEG derivatives

New functional materials based on bacterial cellulose (BC) grafted with poly(ethylene glycol) PEG derivatives for food packaging applications and a facile method for assessing the degradation rates of the final materials are presented. Two types of materials were obtained by grafting the BC films (BCF), respectively lyophilized BC pellicles (BCL) with three PEG derivatives of different molecular weights through radical polymerization. The BC based polymer materials were characterized by SEM, FT-IR, contact angle measurements, and TGA. Tensile tests and DMA analysis were used to compare the two types of materials in terms of shear-modulus, tensile strength and performance giving suitable information for food packaging applications. A new degradation evaluation method, that we propose herein, offers quantitative information about the degradation process in contrast with the SEM analysis, primarily used in literature, which is not decisive in all cases because it characterizes only small parts of the sample. The degradation rates evidenced that the PEG derivatives of higher molecular weight grafted on the surface of BCF led to an acceleration of the degradation process compared with the pristine samples. A good correlation was obtained between the samples analyzed by SEM after the degradation process and their degradation rates were mathematically determined.

A photovoltaic degradation evaluation method applied to bifacial modules

The need to replace fossil energy sources with renewable energy sources to combat global warming has prompted the growth and development of various technologies, including photovoltaics. At the same time the PV technology is evolving to enhance efficiency and durability of PV modules. Bifacial PV modules is gaining larger share of market due to the higher energy and power density at almost the same price of conventional PV modules.In recent years, as PV systems have been operating for a long time, understanding the aging phenomenon of PV modules has become increasingly important. Various types of defects are known that occur during the life of the modules, however, understanding the trend of degradation through a simple quantification of the decrease in performance over time can be a useful tool. The Performance Loss Ratio can give indications about the state of health of the system and can be used for a rough comparison on the performance reduction guaranteed by the module manufacturer and check if the warranty terms are actually respected.In the present study a simple method is used to evaluate Performance Loss Ratio (PLR) on a real PV plant equipped with bifacial PERC modules.Criticalities were highlighted within each phase of the application of the method. The numerical results of the PLR estimate of the photovoltaic modules of the system are reported, calculated on a two-year dataset starting from the date of installation. Finally, the PLR values, that have been estimated using three different metrics and linear fitting, have been compared with the measured average Power decay values associated exclusively with PV modules.The simplicity of the method allows it to be replicated to other case studies.

Remote Sensing of Coastal Wetland Degradation Using the Landscape Directional Succession Model

In recent decades, human activities have impaired the structure, function, and diversity of coastal wetland ecosystems, and there is a need for the rational planning of ecological restoration to curb wetland degradation. However, the challenge remains to quickly and accurately identify degraded wetland areas and their degradation levels. In this study, we used remote sensing interpretation data from 1980 to 2020 and the wetland degradation evaluation method based on a landscape directional succession model to quantify the spatial and temporal characteristics of wetland degradation in Jiangsu Province, China. The key findings showed that 3020.67 km2 of wetlands became degraded over the 40 years of this study, accounting for 42.74% of the total area of coastal wetlands, and that the overall degradation was mild. This degradation presented significant spatial differences, with the wetland degradation in Yancheng City observed to be more serious than that in Nantong City. Degradation mainly occurred in Sheyang County, Dafeng District, Dongtai City, and Rudong County, and the spatial distribution pattern of severe and moderate degradation, mild degradation, and non-degradation was observed from land to sea in that order. The degradation of wetlands was observed to have obvious stages, and the degradation of coastal wetlands in the study area from 1980 to 2020 showed a significant increasing trend. The comprehensive score of wetland degradation in 2020 (1.67) was 3.70 times that in 1985 (0.45), and the turning point occurred in 2000. The types of wetland degradation were dominated by the transformation of natural wetlands into construction land (coastal industry), fish farming, and arable land, as well as the invasion of exotic species. Although great efforts have been made in recent years to protect and restore coastal wetlands, the development and utilization of coastal wetland resources should be strictly controlled to achieve the goal of sustainable development in coastal areas.

Performance Degradation Evaluation of Low Bypass Ratio Turbofan Engine Based on Flight Data

A low bypass ratio turbofan engine operates in a hostile environment, resulting in performance degradation. This seriously affects the security and reliability of the engine. Therefore, a performance degradation evaluation method for engines based on flight data is proposed. The method expands the equation system to solve the underdetermined problem caused by the lack of engine sensors based on multiple operating point analysis. The improved evolution algorithm is employed to solve the equation system, which relieves the problem of insufficient precision. The engine performance degradation dataset is established based on the engine performance calculation model to verify the reliability of the degradation evaluation method. The results show that the method is applicable to the dataset. Finally, the method is applied to the actual flight data to study the law of the performance degradation of the researched engine, which indicates that the engine’s fan efficiency and high-pressure compressor flow capacity have an apparent downward trend over time.

Degradation Evaluation Method with a Test Device for Aging Diagnosis in PV Modules

Generally, PV (photovoltaic) modules are known as devices which are used semi-permanently for more than 20 years, but the electrical performance and lifespan of PV modules can be significantly degraded due to various environmental factors. Thus, a proper evaluation method for aging phenomenon of PV modules is required. Although there already are methods which compare adjusted PV output power based on STC (standard test condition) with initial PV module specification, or perform direct comparison by conducting the test under STC, there are issues with objectivity or efficiency in the existing evaluation method of aging phenomenon due to the data distortion while adjusting measured data or difficulties in implementation. Therefore, in order to overcome the above-mentioned disadvantage of the existing evaluation method for deterioration in PV modules and evaluate the aging characteristics of PV modules based on on-site measurement data in an accurate and efficient manner, this paper implements a test device for aging diagnosis to measure and collect actual data from a PV module section, and presents a modeling of data analysis for aging phenomenon with MATLAB S/W in order to minimize the variability of PV output, communication error, delay, etc. Furthermore, this paper confirms the usefulness of the presented test device for aging diagnosis of the PV modules which is accurately evaluated by considering on-site measurement of PV output power by season.

Discussion on rapid evaluation method of large-scale land degradation in China

This paper discusses the effects of land degradation assessment based on the index of net primary productivity (NPP), rain use efficiency of vegetation (RUE) and relative rain use efficiency of vegetation(rRUE). The results show that the land degradation evaluation method based on the correlation coefficient of NPP with time and the annual average and annual maximum of rRUE can comprehensively reflect the status of land productivity. It plays a good role in indicating the effect of land degradation, and is more conducive to remote sensing quantitative evaluation and rapid monitoring of large-scale land degradation.

Aeroengine Performance Degradation Evaluation Method Based on Hierarchical Bayes Integrated with DNN Fusion Decision

According to the performance degradation law of aeroengine in operation, we proposed a method of aeroengine performance degradation evaluation based on the fusion decision of Hierarchical Bayes method (HB) and deep neural network (DNN). Hierarchical Bayes method was used to build the aeroengine reliability model. Then Based on the aeroengine operation monitoring parameters and reliability model, we used deep learning method to extract the performance degradation law and to evaluate aeroengine performance level, realized the fusion decision of engine performance degradation assessment. 9467 monitoring samples, contaminated with sensor noise, collected from 50 aeroengines was used to evaluate the quality of the network, and the average accuracy is 92.01%. The results showed that this method showed good robustness and reduced the risk of the evaluation results error caused by noise.

A New Performance Degradation Evaluation Method Integrating PCA, PSR and KELM

In order to better characterize the performance degradation trend of rolling bearings, a new performance degradation evaluation method based on principal component analysis (PCA), phase space reconstruction (PSR) and kernel extreme learning machine (KELM), namely PAPRKM is proposed to evaluate the performance degradation of rolling bearings in this paper. In the PAPRKM method, the time-domain and frequency-domain features of the vibration signal are extracted to construct the high-dimension feature matrix. Then the PCA is used to reduce the dimension of the feature matrix in order to represent the running state and the declining trend of rolling bearings, so as to eliminate the redundancy and information conflict among these features. Nextly, the PSR is adopted to obtain more relevant information from the time series. By determining the delay time and embedding dimension, the time series are reconstructed to obtain a new performance degradation index, which is regarded as the input data to input into KELM, and the degradation trend prediction model is established to realize the performance degradation trend prediction. Finally, the actual vibration signals of rolling bearings are applied to prove the effectiveness of the PAPRKM. The obtained experimental results show that the PAPRKM method can effectively predict the performance degradation trend of rolling bearings. The predicted results are more accurate than the other compared methods.

Non-Contact Degradation Evaluation for IGBT Modules Using Eddy Current Pulsed Thermography Approach

In this paper, a non-contact degradation evaluation method for insulated gate bipolar transistor (IGBT) modules is proposed based on eddy current pulsed thermography approach. In non-contact heat excitation procedures, a high-power induction heater is introduced to generate heat excitation in IGBT modules. The thermographs of the whole temperature mapping are recorded non-invasively by an IR camera. As a result, the joint degradation of IGBT modules can be evaluated by the transient thermal response curves derived from the recorded thermographs. Firstly, the non-destructive evaluation principle of the eddy current pulsed thermography (ECPT) system for an IGBT module with a heat sink is introduced. A 3D simulation module is built with physical parameters in ANSYS simulations, and then thermal propagation behavior considering the degradation impact is investigated. An experimental ECPT system is set up to verify the effectiveness of the proposed method. The experimental results show that the delay time to peak temperature can be extracted and treated as an effective indicative feature of joint degradation.

A performance degradation evaluation method for a turbocharger in a diesel engine.

As one of the key systems of the marine power plant diesel engine, the turbocharger directly affects whether the diesel engine can continuously and stably provide the power required for the ship. Owing to a number of uncontrollable factors, such as harsh working conditions and complex structures, the turbocharger may have various failures, causing it to lose its intended function. At present, the fault diagnosis of the marine turbocharger has not been paid enough attention yet and in most cases, the method of ‘ex post diagnosis’ is still adopted. When analysing the nonlinear correspondence between the failure symptoms and failure causes, it is difficult for the existing theories to meet the actual diagnostic requirements. This paper introduces the concept of gas-path diagnosis into the condition monitoring for a marine turbocharger for the first time and proposes the flow capacity index which characterizes the flow capacity of the component and the isentropic efficiency index which characterizes the operating efficiency of the component as two dimensionless evaluation indicators for turbocharger health status. Moreover, the nonlinear mapping relationship between these two health parameters and the gas-path measurable parameters of the turbocharger is studied, and a novel performance degradation evaluation method for a turbocharger is established. The proposed method has been tested in three test cases where the degradation of a model turbocharger has been analysed. These case studies have illustrated that the proposed method can accurately isolate the degraded components and further quantify the degradation of the components.

A Novel Degradation Identification Method for Wind Turbine Pitch System

It’s difficult for traditional threshold value method to identify degradation of operating equipment accurately. An novel degradation evaluation method suitable for wind turbine condition maintenance strategy implementation was proposed in this paper. Based on the analysis of typical variable-speed pitch-to-feather control principle and monitoring parameters for pitch system, a multi input multi output (MIMO) regression model was applied to pitch system, where wind speed, power generation regarding as input parameters, wheel rotation speed, pitch angle and motor driving currency for three blades as output parameters. Then, the difference between the on-line measurement and the calculated value from the MIMO regression model applying least square support vector machines (LSSVM) method was defined as the Observed Vector of the system. The Gaussian mixture model (GMM) was applied to fitting the distribution of the multi dimension Observed Vectors. Applying the model established, the Degradation Index was calculated using the SCADA data of a wind turbine damaged its pitch bearing retainer and rolling body, which illustrated the feasibility of the provided method.

Online Evaluation Method of Electrolytic Capacitor Degradation for Digitally Controlled SMPS Failure Prediction

In this paper, we propose a new capacitor degradation evaluation method aimed at failure prediction and suitable for digitally controlled switching mode power supply (SMPS) for servers. Electrolytic capacitors have one of the highest component failure rates in SMPS; therefore, we attempt to detect an equivalent series resistance degradation of the electrolytic capacitor directly from the data fetched to a digital controller of the SMPS. With a SPICE simulation and a rapid control prototyping evaluation, we confirm the degradation can be detected by the data at a transient response under a normal operation without additional circuits. Even only 10% of a load step change, which commonly occurs in SMPS for servers, causes detectable transient response degradation.

Surface Potential Distribution in Corrosion Degradation Process of Organic Coated Steel

Organic coated steels are generally used in many applications such as cars, appliances and construction. Various methods to evaluate corrosion performance of organic coated metal have been suggested in the past, and for example, visual observation and gross measurement are well known as typical evaluation methods. Electrochemical impedance technique has been widely used for evaluation of under-film corrosion as subjective and quantitative evaluation method. However, the normal technique provides little information on the shape and the location of deteriorated area of organic coated metals. In this work, we focused attention on surface potential measurement which can detect surface reactivity. The purpose of this study is to evaluate the usefulness of surface potential measurement as a non-destructive evaluation method for degradation of coated steels. Carbon steel plates (50mm×50mm×2mm) were used as substrate metals. The metals were coated with clear acrylic lacquer spray. The surface potential was measured by surface reaction measurement device (RM201, Hirocon) having a X-Y stage. The surface potential of the sample with the coating thickness of approximately 10µm was measured at different distance between the sample and Au-probe in order to examine an influence of the distance.Surface potential distribution measurement was performed on the model sample for under-film corrosion. Wet-dry cyclic corrosion test was carried out on the substrate metal by alternating conditions of adding 100µL droplet of 0.5M NaCl solution and drying at 293K and 20%R.H. After 8 cycles, the surface was coated. The coating thickness was approximately 90µm. Surface potential distribution was measured on the sample in laboratory environment (293K, 30%R.H.). The measurement range was 30mm×30mm including the corroded area. The surface profile was also measured with Laser Displacement Sensor (LK-G3000, KEYENCE).Organic coated samples were prepared with about 20µm in thickness. The wet-dry cyclic corrosion test was carried out to these samples. The degradation degree of each sample was different by the repeated cycle number of the corrosion test. The surface potential and profile distribution were measured after corrosion test. For comparison, electrochemical impedance (EIS) measurement was conducted. The sample surface exposed to corrosive environment changed to lower surface potential than the other area. The size and position of the area where surface potential changed corresponded to degradation area. It means that surface potential measurement can detect degradation areas of coated steel even under organic coating.The wet-dry cyclic corrosion test of the organic coated samples was carried out. After several cycles, a part of the surface showed lower potential than the surrounding area. There were a good correlation between the surface potential change area and the organic coating degradation area. The surface potential changed in two stages in degradation process. The first stage corresponds to the gradual change to -0.1V, and the surface potential decreased down to -0.6V. EIS result showed that coating degradation and under-film corrosion occur in the first and second stage, respectively. This result suggests that the degradation process of coated steels can be monitored by surface potential measurement. It is concluded that surface potential measurement is an useful tool to evaluate degradation of coated steels.

적외선 열영상을 이용한 가시광 통신모듈의 고선량 감마선조사에 따른 열화 분석

In this paper, the degradation evaluation method of VLC (Visible Light Communication) wireless module after high dose rate gamma-ray irradiation using the thermal infrared camera is proposed. First, the heating characteristics of the active devices embedded in the VLC wireless module during the condition of normal operation is monitored by thermal infrared camera. By the image processing technique, the trends of the intensity of the heat emitted by the active devices are calculated and stored. The feature of the blob area including the area of the active devices in the thermal infrared image is extracted and stored. The feature used in this paper is the mean value of the gray levels in the blob area. The same VLC module has been gamma irradiated at the dose rate of about 4.0 kGy/h during 72 hours up to a total dose of 288 kGy. And then, the heating characteristics of the active devices embedded in the VLC wireless module after high dose gamma ray irradiation is observed by thermal infrared camera. The high dose gamma-ray induced degradation of the active devices embedded in the VLC module was evaluated by comparing the mean value of the blob area to the one of the same blob area of the VLC module before the gamma ray irradiation.

Development of quality control system for flat-panel detectors

The characteristics of flat-panel detectors (FPD) are degraded by exposure to radiation. Degradation in a FPD progresses locally and has a nonlinear relationship to the radiation dose. In order to manage FPD systems properly, one must perform quality control (QC) such as evaluation of image degradation. However, no evaluation method for degradation has been established. In this paper, we first review the structure and degradation mechanism of FPDs, and then we propose a daily QC system for FPDs. To evaluate the degradation of FPDs, we investigated the number of defective pixels and lines, as well as the offset level of the pixel output. Furthermore, we developed daily QC software for FPD that can evaluate the image quality and is operationally simple. In the experiments, an indirect-conversion type FPD was evaluated by our proposed system. The offset level of FPD increased exponentially with X-ray exposure; no trends were seen for the number of defective pixels and defective lines. The required time for the evaluation of an FPD was about 1min, and no special skills were needed for the analysis. These results indicate that our system may be useful for daily QC of FPDs.

Development of non-destructive evaluation methods for degradation of HTGR graphite components

To develop the non-destructive evaluation method for degradation of HTGR graphite components, the applicability of the micro-indentation method to detect residual stress was studied. The fine-grained isotropic graphites IG-110 and IG-430, the candidates for the VHTR, were used. The following results were obtained: (1) The residual stress in a graphite block at the HTTR in-core condition was analyzed. It was suggested that, for the components in the VHTR which would be used at much severer condition, the development of lifetime extension methods is an important subject. (2) The micro-indentation behavior at stress free condition was investigated with some indenters. The spherical indenter R0.5 mm was selected to detect the specimen surface condition sensitively. The indentation load of 5 and 10 N was selected to avoid the pop-up effect in the loading process. (3) The relationship between the average value of normalized indentation depth and compressive stress of the specimen was expressed by an empirical formula. It would be possible to evaluate the residual stress by the indentation behaviour. It is necessary to assess the variation of data with statistic method and it is the subject of future study.

酸化開始温度による加硫ゴム，プラスチックの劣化評価

Initial oxidation temperature (IOT) is the starting temperature of oxidative exothermal reaction that is observed when the sample is heated at a certain rate under air atmosphere using DSC. It is reported that the IOT figures in a few kinds of rubbers, polyethylene, polypropylene and polyamide66 shift to lower temperatures due to heat degradation. The changes of IOT figures were in line with the changes of residual rate for tensile product measured by tensile test. Here, we report a new method to quantify the degree of degradation of vulcanized rubbers, polyethylene, polypropylene, and polyamide66 by IOT measurement using DSC. The polymers which are applied to this degradation evaluation method included polyethylene, polypropylene, polyamide66, NR, CR, NBR.