Many high concrete-faced rockfill dams (CFRDs) are located in areas with high earthquake intensity where the ground motions are characterized by randomness; consequently, it is significant to study ...the seismic responses and evaluate the seismic performance using dynamic time-history analysis by a stochastic vibration method based on failure probability theory. In this paper, a recently developed generalized probability density evolution method (GPDEM) coupled with a spectral representation-random function method is verified to be suitable for strongly nonlinear structures in high CFRDs during earthquakes by comparing the accuracy and efficiency of the GPDEM with those of the Monte Carlo method (MCM). The GPDEM combined with the currently deterministic dam finite element time-history response analysis using a series of simple and common methods, is adopted to analyze the stochastic seismic responses, dynamic probability evaluation and failure probability of high CFRDs subjected to stochastic earthquake excitation. The statistical and probabilistic information of the typical physical quantities are compared between the GPDEM and MCM after a series of deterministic dynamic calculations, and the dynamic nonlinear behavior of rockfills and the random characteristics of ground motions are presented. The strong correspondence between the results obtained using the traditional stochastic probability MCM analysis and the GPDEM analysis demonstrates the accuracy and effectiveness of the newly proposed method despite its significantly lower computational burden. Finally, the failure probabilities of a high CFRD with different failure grades based on three universal evaluation indices are determined by constructing a virtual GPDEM process. The results demonstrate that the GPDEM shows promise as an approach that can reliably analyze strongly nonlinear structures, such as earth-rockfill dams and other geotechnical engineering structures.
•Seismic time-history response of high CFRDs was analyzed using some simple models and methods.•The precision and efficiency of GPDEM were verified by comparing with MCM.•The statistical and probability information of three typical physical quantities was compared.•The failure probabilities of three universal evaluating indices were obtained based on GPDEM.•The seismic performance of high CFRDs was evaluated from stochastic and probability viewpoint.
•A non-intrusive seepage analysis framework for high dams is proposed.•Seepage safety of high dams considering the spatial variability is studied.•The low failure probability of seepage safety is ...effectively evaluated.•The sensitivity of random parameters was analyzed by grey relational analysis.
Seepage failure of high earth-rockfill dams have devastating consequences, and its safety analysis is of great importance in the design phase. However, the highest safety standards in high dams pose a challenge to the calculated efficiency of safety assessment. To address this problem, a random seepage safety assessment method which can consider the spatial variability of hydraulic parameters is proposed. Firstly, the spatial variability of the hydraulic parameters in the impervious materials is simulated using the covariance matrix decomposition under the framework of the non-intrusive finite element method. Then, according to the safety index of critical hydraulic gradient, the seepage stability formula is established to evaluate the safety state. Finally, considering that the highest safety standards in high dams make the probability of seepage hazard small (low failure probability event), it may require more than 10,000 deterministic calculations to complete the assessment process. Therefore, an efficient method based on subset simulation is proposed to optimize the computational efficiency. After the seepage safety evaluation of a 315 m high dam, the results show that the hydraulic conductivity of the core wall has the greatest influence on the seepage safety of the dam, and even under the influence of strong parameter spatial variability, its seepage failure probability is lower than 10-3. Compared with Monte Carlo simulation, the proposed method requires only 1/11 of the computation time at the 10-3 failure level. In addition, the results of grey relational analysis show that the coefficient of variation and correlation distance have obvious effects on seepage safety, and the autocorrelation distance has a greater effect.
In this paper, a seismic fragility analysis method based on incremental dynamic analysis (IDA) is extended to evaluate the seismic performance of high concrete face rockfill dams (CFRDs). Permanent ...deformation and face-slab damage index using a modified generalized plasticity model for rockfills and a plastic-damage model for face-slabs are considered to be dam damage measures (DMs) after defining a new face-slab damage index. The verification to damage index through the Zipingpu CFRD and previous research indicates that the grading standards are reasonable. Fragility curves and the probabilities are determined for each DM under different earthquake intensities. The results of fragility analysis demonstrate that this method can provide a strong scientific basis for predicting the earthquake destruction and loss of high CFRDs.
•A fragility analysis method is extended to evaluate the seismic performance of CFRDs.•A new damage index is proposed for seismic damage assessment of face-slabs.•Synthetical indexes of dam damage measures are suggested.•Seismic performance of the structure and its various limit states are recognized.•Fragility curves and probabilities are determined for each earthquake intensities.
The evaluation on the performance of environmental regulation is among the hottest topics in environmental economics and management. Although industrial enterprise is the major regulatory objects of ...pollution control, the firm-level pollution abatement effect of environmental regulation has been rarely examined by existing literature. This paper attempts to fill this research gap by investigating the moderating effects of firm heterogeneity on the pollution abatement effect of environmental regulation in China. We establish a theoretical framework which demonstrates that firm heterogeneity determines firms’ compliance capability and willingness through firms’ absorptive capacity, bargaining power, and environmental awareness and then influences firms’ environmental performance under regulatory pressure. Combining firm-level data of pollutant emission with province-level data of environmental regulation, we empirically examine the moderating role of firm heterogeneity on the performance of environmental regulation. We adopt a moderating effect model and estimate it with Logit regression method. It is found that environmental regulation performs better in enterprises with high capital intensity, high total factor productivity (TFP), as well as in state-owned enterprises, export enterprises, and listed companies. In particular, command-and-control regulation performs better in domestic firms than in foreign-owned firms, while the performance of market-based regulation is just the opposite. It is also found that the moderating effect of firm heterogeneity on the performance of environmental regulation varies with regions and industrial sectors, especially for the moderating role of capital intensity and TFP. These findings help to understand the enterprise environmental behavior and provide insights on targeted and differentiated environmental governance from a micro-point of view.
This study aimed to identify factors that affect lymphovascular space invasion (LVSI) in endometrial cancer (EC) using machine learning technology, and to build a clinical risk assessment model based ...on these factors. Samples were collected from May 2017 to March 2022, including 312 EC patients who received treatment at Xuzhou Medical University Affiliated Hospital of Lianyungang. Of these, 219 cases were collected for the training group and 93 for the validation group. Clinical data and laboratory indicators were analyzed. Logistic regression and least absolute shrinkage and selection operator (LASSO) regression were used to analyze risk factors and construct risk models. The LVSI and non-LVSI groups showed statistical significance in clinical data and laboratory indicators (P < 0.05). Multivariable logistic regression analysis identified independent risk factors for LVSI in EC, which were myometrial infiltration depth, cervical stromal invasion, lymphocyte count (LYM), monocyte count (MONO), albumin (ALB), and fibrinogen (FIB) (P < 0.05). LASSO regression identified 19 key feature factors for model construction. In the training and validation groups, the risk scores for the logistic and LASSO models were significantly higher in the LVSI group compared with that in the non-LVSI group (P < 0.001). The model was built based on machine learning and can effectively predict LVSI in EC and enhance preoperative decision-making. The reliability of the model was demonstrated by the significant difference in risk scores between LVSI and non-LVSI patients in both the training and validation groups.
This research mainly addresses evaluating the seismic reliability and analyzing the random dynamic response of high concrete-faced rockfill dam (CFRD) slopes suffering from the near-fault earthquakes ...by establishing a novel method of generating the representative acceleration time histories coupled with the recently proposed generalized probability density evolution method (GPDEM). A probability evaluation is performed after generating two groups of near-fault ground motions, pulse-like and non-pulse-like earthquakes, coupling a series of statistical stochastic parameters with the spectral representation-random function method. A 242-m-high CFRD is selected as an example for finite element stochastic dynamic time series analysis, and second-order statistical values (including mean and standard deviation) and probability information of three indices the safety factor, the cumulative time of safety factor ≤ 1.0 (Fs ≤ 1.0) and the maximum cumulative slippage of the dam slopes are determined, respectively. The effective non-stationary near-fault earthquakes will be adopted to determine the stochastic earthquake loading for the dynamic response evaluation of dam slopes. The statistical and probabilistic results demonstrate that the seismic characteristics make a great difference to the seismic response of slope stability as well as the pulse properties. The stochastic near-fault earthquakes combined with the GPDEM can evaluate seismic performance and reliability effectively from the perspective of randomness, and the failure probability can be obtained directly.
•Seismic performance evaluation of dam slopes subjected to near-fault ground motions is investigated.•A novel method of generating the near-fault ground motions is established.•A recently developed GPDEM is coupled with the representative acceleration time histories.•Statistical and probability information are compared between non-pulse-like and pulse-like ground motions.
This article presents a methodology that discusses a reallocation of carbon emission quotas based on the ZSG-DEA model, also introduces the process of solving the ZSG-DEA model in extensive detail ...and derives Theorems 1 and 2. Theorem 1 shows the equivalence in competition and the cooperation case, while Theorem 2 indicates the correlation between quota adjustment and efficiency change. Through this ZSG-DEA model, the determination of carbon emission quotas is no longer subjective, and reasonable carbon emission quotas among countries can be obtained. The reallocation of carbon emission quotas can not only ensure that all countries have 100% efficiencies, but also help all countries gain through Pareto improvement. The conclusions of this paper are that most developed countries should increase their carbon emission quotas and that most less developed countries need to reduce theirs, including the two most populous countries of China and India. The reallocation process should be paid by selling the quotas of low efficient countries so that they can obtain funds to support their development, while at the same time high efficient countries can produce more due to relaxation of environmental constraints, thus achieving global Pareto improvement.
Silver cluster-assembled materials (SCAMs), by virtue of their tunable structure, accessible surface area and excellent stability, hold great promise as highly efficient catalysts. Herein, we report ...a new SCAM Ag12(S t Bu)6(CF3COO)3(TPyP) n (denoted as Ag12TPyP) composed of a Ag12 chalcogenolate cluster core stabilized by porphyrinic ligands. Ag12TPyP showed superior sulfur mustard simulant (2-chloroethyl ethyl sulfide, CEES) degradation efficiency and achieved a half lifetime (t 1/2) of 1.5 min with 100% selectivity. The experimental results demonstrated that synergistic effects between the silver cluster and photosensitizer ligand promote the efficiency of the generation of singlet oxygen (1O2), which accelerates the decontamination rate. Additionally, benefiting from strong affinity between the silver cluster and CEES, Ag12TPyP exhibits a CEES uptake of 74.2 mg g–1. This work demonstrates that SCAMs offer a new route to the rational design of novel materials for the detoxification of mustard gas.
Niobium pentoxide (Nb2O5), as an important dielectric and semiconductor material, has numerous crystal polymorphs, higher chemical stability than water and oxygen, and a higher melt point than most ...metal oxides. Nb2O5 materials have been extensively studied in electrochemistry, lithium batteries, catalysts, ionic liquid gating, and microelectronics. Nb2O5 polymorphs provide a model system for studying structure–property relationships. For example, the T-Nb2O5 polymorph has two-dimensional layers with very low steric hindrance, allowing for rapid Li-ion migration. With the ever-increasing energy crisis, the excellent electrical properties of Nb2O5 polymorphs have made them a research hotspot for potential applications in lithium-ion batteries (LIBs) and supercapacitors (SCs). The basic properties, crystal structures, synthesis methods, and applications of Nb2O5 polymorphs are reviewed in this article. Future research directions related to this material are also briefly discussed.
