Trend Of Deterioration Research Articles

Effect of thermal fatigue on mechanical properties and microstructure of concrete in constant ambient humidity

The daily and annual temperature differences in mid and high latitudes areas vary greatly, which leads to thermal fatigue deterioration of concrete. The deterioration of concrete properties can also be generated by the cyclic change of humidity in concrete. In the experiment, the thermal fatigue tests of concrete with two strength grades were carried out at the temperature difference of 20 °C, 30 °C, and 40 °C (the initial temperature is 20 °C) under the condition of constant ambient humidity. The macroscopic properties change of concrete such as compressive strength and splitting tensile strength were measured. The microstructure changes of concrete were determined by ultrasonic nondestructive testing technique and mercury intrusion test. The results indicated that thermal fatigue has obvious deterioration effect on concrete. With the increase of temperature difference and cycle number, the strength of concrete decreased dramatically and the decrease of C40 concrete was greater than that of C25 concrete. The splitting tensile strength was more sensitive to thermal fatigue than compressive strength. The ultrasonic wave velocity gradually decreased and the damage factor increased, indicating the internal crack defects of concrete increased. At the same temperature difference, the porosity, total pore volume, average pore diameter, medium pore diameter, and the most probable pore diameter of concrete increased gradually with the increase of the cycle number, while the total pore surface area decreased. The pore structure showed the characteristics of coarsening and the trend of deterioration. The porosity of C40 concrete was less than that of C25 concrete, but the relative change value of porosity was larger, which reveals the internal reason for the strength damage of concrete under thermal fatigue at the microscopic level.

Is recovery just the beginning? Persistent symptoms and health and performance deterioration in post-COVID-19, non-hospitalized university students-a cross-sectional study.

Many individuals experience persistent symptoms such as deteriorated physical and mental health, increased fatigue, and reduced cognitive performance months after recovering from coronavirus disease 2019 (COVID-19). There is limited data on the long-term trajectory and prevalence of these symptoms, especially in milder cases. Our study aimed to assess the persistent effects of COVID-19 on physical and mental health, fatigue, and cognitive performance in a cohort of 214 students, averaging 21.8 years of age. Of these, 148 had contracted COVID-19 but were not hospitalized, with the time since infection ranging from 1 to 39 months. We utilized a comprehensive panel of cognitive tests to measure intelligence, memory, and psychomotor skills, and a detailed anamnestic questionnaire to evaluate physical and mental health. While contracting COVID-19 did not significantly impact overall health and performance, it was associated with increased reports of fatigue. However, the reported severity of the disease had a pronounced negative influence on physical health, mental well-being, fatigue, and reaction time. Trends of improvement in physical and mental health, as well as error rate, were observed within the first 2 years post-infection. However, fatigue and reaction time showed a trend of deterioration. Beyond the 2-year mark, physical health and error rate continued to improve, while mental health began to deteriorate. Fatigue and reaction time continued to decline. Overall, our findings suggest that some effects of contracting COVID-19 can persist or even deteriorate over time, even in younger individuals who had mild cases that did not require hospitalization.

Water Quality Evaluation and Pollution Source Apportionment of Surface Water in a Major City in Southeast China Using Multi-Statistical Analyses and Machine Learning Models

The comprehensive evaluation of water quality and identification of potential pollution sources has become a hot research topic. In this study, 14 water quality parameters at 4 water quality monitoring stations on the M River of a city in southeast China were measured monthly for 10 years (2011-2020). Multiple statistical methods, the water quality index (WQI) model, machine learning (ML), and positive matrix factorisation (PMF) models were used to assess the overall condition of the river, select crucial water quality parameters, and identify potential pollution sources. The average WQI values of the four sites ranged from 68.31 to 77.16, with a clear trend of deterioration from upstream to downstream. A random forest-based WQI model (WQIRF model) was developed, and the results showed that Mn, Fe, faecal coliform, dissolved oxygen, and total nitrogen were selected as the top five important water quality parameters. Based on the results of the WQIRF and PMF models, the contributions of potential pollution sources to the variation in the WQI values were quantitatively assessed and ranked. These findings prove the effectiveness of ML in evaluating water quality, and improve our understanding of surface water quality, thus providing support for the formulation of water quality management strategies.

Artificial intelligence can use physiological parameters to optimize treatment strategies and predict clinical deterioration of sepsis in ICU

Objective. Sepsis seriously threatens human life. Early identification of a patient’s risk status and appropriate treatment can reduce septic shock risk and mortality. Our purpose is to design and validate an adjunctive therapy system based on deep reinforcement learning (DRL), which can provide treatment recommendations with providence and assess the patient’s risk status and treatment options in the early stages. Approach. Data is from the Beth Israel Deaconess Medical Center. The raw data included 53 423 patients from MIMIC-III. Of these, 19 620 eligible samples were screened to form the final cohort. First, the patient’s physiological parameters were fed into the DRL therapy strategy recommendation module (TSRM), which provides a forward-looking recommendation for treatment strategy. The recommended strategies were then fed into the reinforcement learning risk assessment module (RAM), which predicts the patient’s risk status and treatment strategy from a long-term perspective. The DRL model designed in this paper assists in formulating treatment plans and evaluating treatment risks and patient status through continuous interaction with patient trajectory; this model therefore has the foresight that a supervising deep learning model does not. Main results. The experiment shows that, in the test set for the TSRM, mortality is the lowest when the treatment strategy that is actually implemented is the same as the AI-recommended strategy. Regarding the RAM, it can accurately grasp a patient’s deterioration trend, and can reasonably assess a patient’s risk status and treatment plans at an early stage. The assessment results of the model were matched with the actual clinical records. Significance. A DRL-based sepsis adjunctive therapy model is proposed. It can prospectively assist physicians in proposing treatment strategies, assess the patient’s risk status and treatment methods early on, and detect deterioration trends in advance.

Modified Rheological Model for Deep‐Buried Silty Mudstone and Support Time Analysis Application

The rheological properties of soft rocks should be considered in the long‐term design and maintenance of deep‐buried tunnels using uniaxial single‐stage loading and graded incremental cyclic‐loading methods. In this article, creep tests were performed on deep‐buried silty mudstone from a specific water conveyance tunnel in China, with a buried depth in the range of 1650–2320 m and subjected to high in situ stress. The creep curves of silty mudstone under different loading stresses were obtained, showing evident rheological mechanical behavior under complicated external environmental conditions. Based on the classic Burgers rheological model, a new nonlinear creep model was established based on the creep properties of deep‐buried silty mudstone in the project area. Typically, the designated rheological models for certain projects are unsuitable or inadequate. A nonlinear dashpot was calculated using the Levenberg–Marquardt (L–M) method coupled with origin to account for the deterioration trend in the strength of the silty mudstone over time. With the determined parameters, the modified Burgers model exhibited good qualitative consistency with field monitoring data. The user‐defined material mechanical behavior (UMAT) subroutine of the modified Burgers model was successfully achieved after it was implemented in the numerical code ABAQUS. Based on the full‐rheological effect, the proper supporting time of a deep‐buried tunnel was studied, and it was proposed that a second lining should be cast in situ approximately 150 days after the excavation of the tunnel. The outcomes of the proposed modified rheological model can accurately represent the creep behavior of deep‐buried silty mudstones in a specific engineering instance. The research results can provide a basis for the rheological behavior and supporting time of deep‐buried silty mudstone.

A novel model-based unbalance monitoring and prognostics for rotor-bearing systems

A novel model-based unbalance monitoring and prognostics for rotor-bearing systems is introduced in the paper. An analytical method is first applied for rotor modeling and the calculated first natural frequency is validated by an FEM model. The rotor-bearing model with the identified bearing parameters is next validated with an operational 3-stage turbine-bearing’s machine on the first critical speed. The novelty of the approach is that the unbalance proceeding with optimization schemes is evaluated in two phases. In phase I, the bearing parameters and the initial unbalances are simultaneously evaluated based on the operational data soon after an overhaul. In phase II, the unbalance deterioration with time is identified through every day’s measured vibration at two bearings. A set of operational data over 16 months, provided by a local company, are used to test the approach. The evaluated unbalance deterioration trend is verified by the collaborated company from two consecutive overhauls. Five optimization algorithms are also tested and the results prove the robustness of the derived approach. Finally, the unbalance forecasting capability extrapolating from historical unbalance curve is demonstrated and that can work as prognostics in a condition-based maintenance strategy.

东北虎豹国家公园生态环境质量动态评价及其气候响应

PDF HTML阅读 XML下载 导出引用 引用提醒 东北虎豹国家公园生态环境质量动态评价及其气候响应 DOI: 10.5846/stxb202204130981 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 吉林省科技发展项目（20210203152SF）；中国气象局创新发展专项（CXFZ2021J076） Dynamic evaluation of ecological environment quality and climate response in Northeastern China Tiger and Leopard National Park Author: Affiliation: Fund Project: 省、部研究计划基金 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:人类活动及气候变化对东北虎豹国家公园生态环境产生深刻的影响，探究该地区生态环境质量的时空演变规律对园区可持续发展具有重要意义。在原有遥感生态指数基础上，选用增强型植被指数代替原绿度指标中的归一化植被指数，构建2001-2020年植被生长季遥感生态指数，探讨园区内核心保护区、虎豹潜在栖息地及主要人口聚集区三大管控区生态环境质量时空变化特征，并基于像元尺度分析其对气候因素的响应。结果表明：（1）近20年虎豹公园生态环境质量呈波动微弱下降趋势，2015年后生态环境质量逐步提升，2020年达到良好水平；（2）园区内各管控区生态环境质量具有明显的空间分异性，东部核心保护区中部及虎豹潜在栖息地中部以南地区生态环境质量较好，主要人口聚集区相对较差。（3）近20年虎豹公园生态环境质量稳定性较差。未来生态环境质量变化趋势为上升的面积占60.86%，表明未来生态环境趋势总体向好，但局部地区仍存在持续恶化态势。（4）虎豹公园生态环境质量主要受降水的影响，与降水呈显著正相关关系，与气温及日照的相关性较弱。 Abstract:Human activities and climate change have a profound impact on the ecological environment of the Northeastern China Tiger and Leopard National Park (NCTL-NP), and exploring the temporal and spatial evolution of the ecological environment quality in this area is of great significance for the sustainable development of the park. In this paper,we selected the enhanced vegetation index (EVI) to replace the NDVI in the original greenness index, and constructed the remote sensing ecological index (RSEI) for the vegetation growing season from 2001 to 2020 based on the original remote sensing ecological index. Then, we analyzed the temporal and spatial variation characteristics of the ecological environment quality and their responses to climatic factors in the three major control areas of potential habitats and main population agglomeration areas based on the pixel scale. The results show that:(1) The ecological environment quality of NCTL-NP has shown a fluctuating and weak downward trend in the past 20 years. After 2015, the ecological environment quality has gradually improved and reached a good level in 2020; (2) The ecological environment quality of each control area in the park has obvious spatial heterogeneity, the quality of the ecological environment in the central part of the eastern core reserve and the southern part of the potential habitat of tigers and leopards is relatively good, while the main population agglomeration areas are relatively poor. (3) In the past 20 years, the ecological environment quality of NCTL-NP has been extremely unstable.The area with an upward trend in the quality of the ecological environment in the future accounted for 60.86%, indicating that the trend of the ecological environment in the future is generally good, but there is still a continuous deterioration trend in some areas. (4) The ecological environment quality of NCTL-NP is mainly affected by precipitation, which has a significant positive correlation with precipitation, and a weak correlation with temperature and sunshine. 参考文献 相似文献 引证文献

Identification of priority conservation areas based on ecosystem services and systematic conservation planning analysis.

In order to reverse the trend of ecological deterioration and resolve the conflict between ecological conservation and economic development, it is necessary to evaluate the trends of ecosystem services (ESs) and unravel the relationship between ESs and environmental drivers and identify the priority areas for ESs. In this research, we used the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model to quantify the variation of four important ESs (water purification, water yield, soil conservation, and habitat quality) in the Dongting Lake Basin from 2000 to 2015. During the past 15years, water yield was declined by 3.38% and soil conservation was increased by 1.45%. Water quality purification was deteriorated with the rise in phosphorus export (5.32%) and nitrogen export (4.09%). Meanwhile, habitat quality was decreased by 3.27%. Trade-offs occurred primarily among water yield and other ESs. Social-ecological drivers importance analysis found that water yield was primarily influenced by precipitation and temperature. By contrast, water purification and habitat quality were more affected by the distribution of land use and land cover (LULC). Soil conservation was closely related to precipitation and geographical factor. Based on the distribution of ESs and the intensity of human activities, we delineated priority areas for each ESs using the systematic conservation planning tool (Marxan). LULC shifted most dramatically in water yield reserves (6.49%) with a large amount of lands conversed to cropland (4.4%) and build-up land (0.27%), which further increased the risk of water scarcity, while LULC changed less in other ESs priority areas due to human activities. Our study helps develop conservation strategies within specific area cost-effectively and provides scientific support for future conservation program of ESs formulation and adjustment.

Design of extended Kalman filter observer coupled to ammonia cross-sensitivity model for an SCR system

Commercial diesel vehicles that comply the China/EURO VI emission regulations are generally equipped with selective catalytic reduction (SCR) systems for reducing [Formula: see text] emission and [Formula: see text] sensors at its downstream for accurate closed-loop control. However, [Formula: see text] sensors have significant ammonia cross-sensitivity pushing up their readings. Moreover, for the closed-loop control of SCR systems effectively estimating the critical states from the [Formula: see text] sensor readings remains a further challenge. In this paper, an ammonia cross-sensitivity model with segmented sin and quadratic composite functions describing high frequency characteristics is established by analyzing the experimental data of an SCR system. A control-oriented three-states model of an SCR system is established, and based on it an extended Kalman filter (EKF) observer coupled to the ammonia cross-sensitivity model is proposed. The simulation results show that from the [Formula: see text] sensor readings the EKF observer can effectively estimate the deterioration trend of the [Formula: see text] and [Formula: see text] emissions, and describe the dynamic change process of the ammonia coverage rate. The experimental results under the four non-excitation cycles show that the EKF observer can effectively estimate the deterioration trend, that the average estimated accuracy of [Formula: see text] and [Formula: see text] during their deterioration stage can respectively reach 86.16% and 54.87%, and that the observer has better robustness to disturbances from the operating conditions.

Study on the deterioration trend of the rock mass on the reservoir banks under dry-wet cycles

The deterioration of rock mass under dynamic mechanical state is difficult to determine, especially when evolution trends of micro-fractures are considered. Taking the limestone from Wuxia section of the Three Gorges Reservoir area as studying case, cross-scale tests and theoretical analysis were adopted to study the influence of dry-wet cycles on rock deterioration. The weakly acidic condition (pH = 6) and the dry environment at 105°C were together constituted the two extreme mechanical states of the dry-wet cycles. Meanwhile, the number of dry-wet cycles and soaking time were used as the main variables to analyze the deterioration trend. After introducing the damage mechanics, the quantitative relationship between the mechanical parameters and changing mechanical states was obtained. Combined with the microstructure obtained by scanning electron microscope (SEM), it can be found that with the increase of dry-wet cycles and soaking time, the morphology of mineral particles changed, the number of secondary pores gradually increased, the surface structure became looser, and the microcracks gradually increased, causing the decrease of macro strength. The related method proposed in this paper could provide significant references to determine the mechanical parameters of rocky reservoir bank.

Perilla frutescens essential oil as a potential fumigant against quality deterioration of post-harvested rice caused by Aspergillus flavus

Strategies to prevent the growth of mycotoxin-producing fungi in agricultural products need to be identified. In this study, the antifungal efficacy of Perilla frutescens essential oil (PEO) as a fumigant against Aspergillus flavus (A. flavus) in stored rice seeds was investigated. PEO affected the permeability and integrity of the A. flavus cell membrane, as evidenced by the decreased cell viability. In situ assays demonstrated that fumigation with PEO significantly reduced and retarded the growth of A. flavus in stored rice seeds but the germination rate decreased with increasing concentration of PEO. PEO could alleviate rice seeds’ color differences by reducing the degree of rice seeds browning, as evidenced by a decrease in polyphenol oxidase in PEO-fumigated rice seeds. Moreover, the rice seeds with PEO fumigation exhibited higher soluble protein content and catalase (CAT) activity, which collectively suggests that PEO promotes the tolerance of rice seeds to A. flavus. Furthermore, decreases in fatty acid value (FAV), malondialdehyde (MDA) content, and acceptable sensorial characteristics were observed in the rice seeds after PEO fumigation, indicating that fumigation with PEO can effectively delay the trend of quality deterioration in high moisture rice seeds during storage. These results recommended PEO as a potential green preservative for the shelf-life extension of stored grain.

Evolution and improvement options of ecological environmental quality in the world's largest emerging urban green heart as revealed by a new assessment framework

Large ecological green spaces in cities are often designated as Urban Green Hearts (GHs) to support the ecological and recreational needs of urbanites. While GHs protection and sustainable development have been a high priority for urban planning and management, ecological environment quality (EEQ) of GHs has rarely been monitored and assessed. Here, we proposed a comprehensive assessment framework for EEQ based on entropy weights and rank-sum ratios methods, and applied the framework to the world's largest GH, Changsha-Zhuzhou-Xiangtan urban agglomeration Green Heart (CZT-GH), and its 5 km and 10 km buffer zones to examine the spatial-temporal dynamics of its EEQ from 2000 to 2019. Compared with the buffer zones, the EEQ in the CZT-GH was the best, with an annual average of 44.92 % of the area being High-grades EEQ. The restoration trend of EEQ was most conspicuous in only 8.4 % of CZT-GH, a small fraction compared with 25.1 % and 66.5 % of the CZT-GH showing deterioration trend and no change, respectively. Five factors were identified that calls for management attention: land use and cover change, spatial heterogeneity in vegetation restoration, temporal fluctuation in air quality improvement, comprehensive EEQ assessment and restoration, and capacity to cope with ecological risks. The approach, issues identified, and management measures proposed in this study should be applicable to GHs in general. The generic EEQ assessment framework and approaches developed in this study are generic and objective and therefore can be easily adapted to other regions; the procedures used to quantify the spatial and temporal changes of EEQ and identify underlying management issues provide essential information for formulating adaptive management measures of EEQ in general. SynopsisTaking the largest urban Green Heart as a case study, we established and applied a new general ecological environment quality (EEQ) evaluation system to monitor EEQ changes, identify issues, and propose management options.

Effectiveness analysis of modified tibial transverse bone transport technique combined with vancomycin calcium phosphate bone cement local filling and covering in treatment of diabetic foot

To investigate the effectiveness of modified tibial transverse bone transport technique combined with vancomycin calcium phosphate bone cement local filling and covering in the treatment of diabetic foot (DF). The clinical data of 22 DF patients treated with modified tibial transverse bone transport technique combined with vancomycin calcium phosphate bone cement local filling and covering between October 2019 and December 2021 were retrospectively analyzed. There were 13 males and 9 females with an average age of 61.3 years (range, 41-74 years). The duration of diabetes mellitus was 8-30 years, with an average of 12.5 years, and the duration of DF was 10-42 days, with an average of 28.2 days. There were 2 cases of grade 3 and 20 cases of grade 4 according to Wagner classification. CT angiography was performed on both lower extremities of the patients, and the blood vessels of the affected extremities were narrowed to varying degrees and the blood supply was poor. The preoperative skin temperature of affected foot was (28.27±0.91)°C, the ankle brachial index (ABI) was 0.42±0.11, and the visual analogue scale (VAS) score was 7.7±0.6. Preoperative size of DF ulcer ranged from 2.5 cm×2.0 cm to 3.5 cm×3.0 cm. The skin temperature of affected foot, ABI, VAS score, and skin wound healing of the affected foot were recorded and compared between before operation and at 3 months after operation. All patients were followed up 3-18 months, with an average of 10.5 months. The infection of 1 patient with Wagner grade 4 did not improve significantly after operation, and there was a trend of further deterioration, and the amputation of the left leg was finally performed at 22 days after operation.The remaining 21 patients recovered well after operation, the external fixator was removed at 1 month after operation, the wound healed at 3 months after operation, and there was no recurrence of ulcer in situ or other sites during follow-up. At 3 months after operation, the skin temperature of affected foot was (31.76±0.34)°C, the ABI was 0.94±0.08, and the VAS score was 2.1±0.3, which significantly improved when compared with those before operation ( t=25.060, P<0.001; t=32.412, P<0.001; t=-51.746, P<0.001). Modified tibial transverse bone transport technique combined with vancomycin calcium phosphate bone cement local filling and covering for DF patients can effectively improve the blood supply of the affected limb, promote wound healing, and improve effectiveness.

Eco-environmental effects and spatiotemporal evolution characteristics of land use change: A case study of Hexi Corridor, Northwest China.

Based on the land use data of Hexi Corridor region from 1980 to 2020, we calculated the ecological environment quality index and analyzed the spatial and temporal evolution characteristics, change frequency, patterns, circles of the long time series land use type changes and its ecological environment quality, using the spatial analysis method of ArcGIS. The results showed that unused land was the main land use type in the study area during 1980-2020. The area of construction land, forest land, grassland, and water changed more, and the transition among land use types was obvious. The trends of deterioration and improvement of ecological environment quality in the study area occurred simultaneously and offset each other under certain conditions. The ecological environment quality index evolved in a 'U' shape, first decreasing and then increasing, with little change in overall ecological environment quality fluctuations. The spatial clustering of ecological quality was obvious, which was higher in the southeast and lower in the northwest, without high frequency and large change. The ecological quality in the southeast quadrant of the study area was the worst, followed by the southwest and northwest quadrants, while the ecological quality in the northeast quadrant was the best. The area of the continuously decline zone in ecological environment quality type conversion was larger than that of the continuously rising zone, indicating that ecological environmental protection in the Hexi Corridor had been effective during the study period. The hot spots of ecological quality change were mainly distributed in the central and southwestern part of the Hexi Corridor, and the cold spots were mainly distributed in the northwestern part.

A combined risk-based and condition monitoring approach: developing a dynamic model for the case of marine engine lubrication

Abstract This paper focuses on the creation of a dynamic probabilistic model which simulates deterioration trends of a marine engine lubrication system. The approach is based on risk and the implementation is achieved through a dynamic Bayesian network (dBN). Risk can be useful for decision making, while dBNs are a powerful tool for risk modelling and prediction models. The model takes into account deterioration of engine components, oil degradation and the off-line condition monitoring technique of oil analysis, in the context of predictive maintenance. The paper aims to efficiently predict probability evolution for main engine lubrication failure and to decide upon the most beneficial schemes from a variety of lubrication oil analysis interval schemes by introducing monetary costs and producing the risk model. Real data and respective analysis, along with expert elicitation, are utilized for achieving model quantification, while the model is materialized through a code in the Matlab environment. Results from the probabilistic model show a realistic simulation for the system and indicate the obvious, that with more frequent oil analyses and respective maintenance or repairs, the probability of failure drops significantly. However, the results from the risk model highlight that the costs can redefine scheme suggestions, as they can correspond to low probabilities of failure but also to higher costs. A two-month interval scheme is suggested, in contrast to the most preferred practice among shipping companies of a three-month interval. The developed model is in general identified as a failure prediction tool focusing on marine engine lubrication failure.

Dynamic changes in liver function after transjugular intrahepatic portosystemic shunt in patients with cirrhosis

PurposeTo evaluate the dynamic changes in liver function after transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with cirrhosis and to explore its association with clinical outcomes. MethodsThis retrospective study included patients who underwent TIPS between August 2016 and December 2020. Liver function was primarily evaluated using the model for end-stage liver disease (MELD) score, which was analyzed at baseline, 1 week, 1 month, 3 months, 6 months, and 12 months using one-way repeated measures ANOVA. The Kaplan-Meier method, log-rank test, and multivariate analysis were used as appropriate. ResultsIn total, 235 patients were included in this study. The MELD score was significantly higher at 1 week (11.8 ​± ​3.1 vs 13.5 ​± ​3.5, p ​< ​0.05) and 1 month (11.8 ​± ​3.1 vs 13.2 ​± ​4.6, p ​< ​0.05) than the baseline level and recovered at 3 months (11.8 ​± ​3.1 vs 11.9 ​± ​3.9, p ​> ​0.05). At 12 months, the MELD score was higher than the baseline level (11.8 ​± ​3.1 vs 12.4 ​± ​3.2, p ​< ​0.05). Patients with a recovery of the MELD score (n ​= ​151) at 3 months had a lower probability of overt and severe HE (log-rank p ​= ​0.015 and p ​= ​0.027, respectively) than those without recovery (n ​= ​84). Logistic regression analysis revealed that albumin (odds ratio [OR], 0.926; 95% confidence interval [CI], 0.863–0.992; p ​= ​0.029) and platelet count (OR, 0.993; 95% CI, 0.987–0.999; p ​= ​0.033) were independent predictive factors for non-recovery of the MELD score at 3 months. ConclusionsLiver function after TIPS creation showed a trend of deterioration at first, followed by recovery. Recovery of liver function at three months was associated with reduced overt and severe HE.

Land Space Change Process and Its Eco-Environmental Effects in the Guanzhong Plain Urban Agglomeration of China

Urban agglomeration is the strategic core area of social–economic high-quality development in the world. However, high-density agglomeration and high-speed expansion have caused dramatic changes in land space, leading to prominent eco-environmental problems and, thus, threatening human well-being. How to solve the contradiction between urban agglomeration land expansion and eco-environment protection has become an urgent scientific problem. In this paper, we constructed a framework of assessing land space change and its eco-environmental effects in the urban agglomeration by using the Geo-informatic Graphic, eco-environmental quality index (EQI), and eco-environmental contribution rate. We then quantitatively analyzed the characteristics of land space transition as well as its eco-environmental effects in the Guanzhong Plain urban Agglomeration (GPUA) based on the land use data in 1990, 2000, 2010 and 2020. The results indicated that from 1990 to 2020, the production space of the GPUA continued to shrink, the living space continued to expand, and the ecological space showed a fluctuating increasing trend. There were significant regional differences in the land space change of the GPUA, with 92.2% of the counties showing a significant contraction in agricultural production space, 93.3% and 91.1% showing a significant expansion in urban and rural living space, and 64.4% showing an increase in woodland ecological space. Agricultural production space is transformed into ecological space and living space, and living space occupies ecological space and agricultural production space, which is the main mode of land space transition in the GPUA. With the continuous expansion of low-quality and high-quality areas of the eco-environment and the continuous contraction of medium-quality areas, the improvement and deterioration of the eco-environmental quality of the GPUA have coexisted, first showing a trend of deterioration and then improvement. The transition of agricultural production space into grassland and woodland ecological space improved the eco-environmental quality, while the transition of grassland ecological space into agricultural production space, and the occupation of agricultural production space by urban and rural living space as well as industrial and mining production space resulted in the deterioration of eco-environmental quality. The findings of this study may provide a theoretical basis for optimizing the allocation of land space resources in ecologically fragile urban agglomeration.

An Innovation of the Markov Probability Model for Predicting the Remaining Service Life of Civil Airport Rigid Pavements.

In view of the time series update of airport runway health status detection data, the Markov chain of stochastic process theory was adopted. Considering the influence of aircraft traffic load, age, and pavement structure surface-layer thickness on the performance deterioration process of airport runways, the method of survival analysis was used. The parameter model of survival analysis was used to establish the duration function model of the four condition states of the airport runway PCI (pavement condition index). The Markov transition matrix for the performance prediction of airport runways was constructed. In order to evaluate the ability of the Markov transition matrix method to predict the trend of deterioration for PCI of the airport runway under different conditions of aircraft traffic volume and thickness of the runway pavement surface, a data set was constructed with the actual inspection data of the airport runway, and the corresponding samples were selected for analysis. The results showed that a Markov transition matrix for airport runway performance prediction, constructed based on survival analysis theory, can combine discontinuous inspection data or monitoring data with Weibull function survival curves. The method proposed in this paper can quantitatively predict the remaining service life of airport runways and provide support for cost-effective decisions about airport pavement maintenance and rehabilitation.

Degradation Trend Prediction of Hydropower Units Based on a Comprehensive Deterioration Index and LSTM

Deterioration trend prediction of hydropower units helps to detect abnormal conditions of hydropower units and can prevent early failures. The reliability and accuracy of the prediction results are crucial to ensure the safe operation of the units and promote the stable operation of the power system. In this paper, the long short-term neural network (LSTM) is introduced, a comprehensive deterioration index (CDI) trend prediction model based on the time–frequency domain is proposed, and the prediction accuracy of the situation trend of hydropower units is improved. Firstly, the time–domain health model (THM) is constructed with back-propagation neural network (BPNN) and condition parameters of active power, guide vane opening and blade opening and the time–domain indicators. Subsequently, a frequency-domain health model (FHM) is established based on ensemble empirical mode decomposition (EEMD), approximate entropy (ApEn), and k-means clustering algorithm. Later, the time–domain degradation index (TDI) is developed according to THM, the frequency-domain degradation index (FDI) is constructed according to FHM, and the CDI is calculated as a weighted sum by TDI and FDI. Finally, the prediction model of LSTM is proposed based on the CDI to achieve degradation trend prediction. In order to validate the effectiveness of the CDI and the accuracy of the prediction model, the vibration waveform dataset of a hydropower plant in China is taken as a case study and compared with four different prediction models. The results demonstrate that the proposed model outperforms other comparison models in terms of predicting accuracy and stability.

A complex approach to continuous cardiac monitoring of neoadjuvant chemotherapy: Observational study

A complex approach to continuous cardiac monitoring of neoadjuvant chemotherapy: Observational study