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Seepage is the primary cause of dam failures. Conducting regular seepage analysis for dams can effectively prevent accidents from occurring. Accurate and rapid determination of seepage parameters is a prerequisite for seepage calculation in hydraulic engineering. The Whale Optimization Algorithm (WOA) was combined with Support Vector Regression (SVR) to invert the hydraulic conductivity. The good point set initialization method, a cosine-based nonlinear convergence factor, the Levy flight strategy, and the Quasi-oppositional learning strategy were employed to improve WOA. The effectiveness and practicality of Improved Whale Optimization Algorithm (IWOA) were evaluated via numerical experiments. As a case study, the seepage parameters of the Dono Dam located on the Baishui River in China were inversed, adopting the proposed inversion model. The calculated seepage field was reasonable, and the relative error between the simulated head and the measured value at each monitoring point was within 2%. This new inversion method is more feasible and accurate than the existing hydraulic conductivity estimation methods. [ABSTRACT FROM AUTHOR]

Ensuring the long-term, efficient, and safe operation of reservoir dams relies on the slope stability of embankment dams. Periodic fluctuations of the reservoir water level due to reservoir scheduling operations make the slope of the reservoir bank vulnerable to instability. To investigate the influence of various factors and their interactions with embankment dam slope stability under changing reservoir water levels, a global sensitivity analysis method is proposed that accounts for seepage–stress coupling. An embankment dam in Shaanxi Province, China, is studied as an example, with COMSOL Multiphysics software simulating the seepage and slope stability of the dam under fluctuating reservoir water level conditions and seepage–stress coupling. The global sensitivity analysis of factors affecting dam slope stability is accomplished by combining Plackett–Burman and Box–Behnken experimental designs, with ANOVA determining the sensitivity of each factor and interaction term. The results demonstrate that during the impoundment period of the reservoir, the saturation line is concave, and the overall stability safety of the dam slope increases first and then tends to be stable, according to the coefficient. The internal friction angle φ, cohesion c, and soil density ρs represent the three most sensitive factors affecting the stability and safety of the dam slope, while c × ρs is a second-order interaction term with significant sensitivity to the stability and safety coefficient of the dam slope. The reservoir drainage period infiltration line is convex, and dam slope stability first reduced and then increased. The magnitude of water level change H, internal friction angle φ, cohesion c, and soil density ρs are the four most sensitive factors for the coefficient of safety of dam slope stability, while c × ρs, H × ρs, and φ × ρs are the second-order interaction terms with significant sensitivity to the coefficient of safety of dam slope stability. These research findings and methods can offer valuable technical support and reference for the investigation and evaluation of the stability of embankment dam slopes. [ABSTRACT FROM AUTHOR]

Seepage is a main cause of dam failure, and its stability analysis is the focus of a dam's design, construction, and management. Because a geological survey can only determine the range of a dam foundation's hydraulic conductivity, hydraulic conductivity inversion is crucial in engineering. However, current inversion methods of dam hydraulic conductivity are either not accurate enough or too complex to be directly used in engineering. Therefore, this paper proposes a new method for the inversion of hydraulic conductivity with high application value in hydraulic engineering using an improved genetic algorithm coupled with an unsaturated equivalent continuum model (IGA–UECM). This method is implemented by a new code that fully considers engineering applicability. In addition to overcoming the premature convergence shortcomings of traditional genetic algorithms, it converges faster than Bayesian optimization and tree-structured Parzen estimator inversion algorithms. This method is verified by comparing the water head from drilling exploration and inversion. The results of the inversion are used to study the influence of a cement grouting curtain layout scheme on the seepage field of the Hami concrete-face rockfill dam in China, which is used as an engineering application case of the IGA–UECM. The law of the seepage field is reasonable, which verifies the validity of the IGA–UECM. The new inversion method of hydraulic conductivity and the proposed cement grouting curtain layout in this study offer possible strategies for the design, construction, and management of concrete-face rockfill dams. [ABSTRACT FROM AUTHOR]

The seepage parameters of the dam body and dam foundation are difficult to determine accurately and quickly. Based on the inverse analysis, a Gray Wolf Optimizer (GWO) was introduced into this study to search the target hydraulic conductivity. A novel approach for initialization, a polynomial-based nonlinear convergence factor, and weighting factors based on Euclidean norms and hierarchy were applied to improve GWO. The practicability and effectiveness of Improved Gray Wolf Optimizer (IGWO) were evaluated by numerical experiments. Taking Kakiwa dam located on the Muli River of China as a case, an inversion analysis for seepage parameters was accomplished by adopting the proposed optimization algorithm. The simulated hydraulic heads and seepage volume agree with measurements obtained from piezometers and measuring weir. The steady seepage field of the dam was analyzed. The results indicate the feasibility of IGWO in determining the seepage parameters of Kakiwa dam. [ABSTRACT FROM AUTHOR]

The deformation of dams has always been the focus of dam safety research. To more accurately study the effect of the Duncan–Chang model on the deformation of homogeneous Earth dams, this paper simulates the displacement variation of a homogeneous Earth dam through the finite element method based on the Duncan–Chang E-B model. The sensitivity of the Duncan–Chang E-B model parameters and the dam material density on the displacement of a homogeneous earthen dam in Gansu Province, China, were investigated using single-factor and multifactor analysis methods. The results show that the displacement variation of the dam during the completion and operation periods is consistent with the general rule for Earth and rock dams; the three parameters R f , φ 0 , and Δ φ are more sensitive to dam deformation; and the three parameters m , n , and K are less sensitive to dam deformation. [ABSTRACT FROM AUTHOR]

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• We verify the mediation effect of technical efficiency between bus facility scale and ridership attraction. • Multigroup analysis is used to explore the variable returns to scale in bus system. • When bus facility scale is small, an increase in scale can enhance ridership attraction through higher technical efficiency. • When bus facility scale is excessive, ridership attraction suffers from the negative impact of a lower technical efficiency. • Different policies are proposed based on the actual situations faced by the cities. Bus ridership in many cities has not increased but, ultimately, decreased with the continuous growth of the bus facility scale in recent years in China. This study aims to explore the relationship between bus facility scale and ridership attraction by introducing technical efficiency as a mediator variable, and data collected from 152 Chinese cities in 2015 is used in the study. Technical efficiency in this paper refers to the degree to which a bus system attains its minimum inputs (labor, bus facility) with a given level of output (vehicle-km). Results show that the technical efficiency has a mediation effect. When bus facilities are few and insufficient, an increase in facilities can considerably enhance ridership attraction through higher technical efficiency, but when the scale of bus facilities increases to an excess, ridership attraction suffers from the negative impact of a lower technical efficiency. This study offers a theoretical explanation and provides decision support for policy-makers who would like to strengthen bus ridership attraction. [ABSTRACT FROM AUTHOR]

• We investigate the direct impacts of private cars' symbolic value on bus use. • We assume the travel mode choice is affected by the public transit priority policy. • We confirm the effects of private cars' symbolic value on public transit use. • Our findings support the current measures of the public transit priority policy. • It is necessary to change Chinese understandings of using buses and private cars. Because of the symbolic value of the private car, driving a private car is a signal of wealth and a particular social status, but public transit is considered to be a means of transport for low- and middle-income people in the traditional culture of China, especially in face culture. Some prior studies have verified the impact of the symbolic value of the private car on car use and further indirectly speculated about its impact on public transit use, but these studies have seldom focused on the direct effect of the symbolic value of the private car on public transit use. Based on face-to-face questionnaire survey data from a sample of 323 commuters with experience using buses in Changzhou in 2016, this case study examines the relationship among the symbolic value of the private car and passenger satisfaction with bus services and bus use by using binary logit regression. The empirical results show a stable negative association between the symbolic value of the private car and bus use, while the passenger satisfaction with bus services is positively associated with bus use. These findings imply that improving the public transport services is important for the public transit priority policy, and the policy could be more effective if the Chinese traditional understandings of using public transit and private cars are changed. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to determine whether the perineal body (PB) is different between women with and without prolapse and to analyze its association with prolapse., Methods: This cross-sectional observational study was performed in a tertiary-level urology department and included patients with stage II-IV pelvic organ prolapse (POP) and normal controls with all points 1 cm or more above the hymen. The patients underwent supine midsagittal magnetic resonance imaging (MRI) at rest and during the maximum Valsalva maneuver. Perineal mobility and PB length, height, perimeter, and area were measured; in addition, the genital hiatus and PB were measured according to the definition of the Pelvic Organ Prolapse Quantification system. Univariate associations of POP with characteristics were assessed using the chi-square test or Fisher exact test for categorical variables and the t test for continuous variables. Multivariate logistic regression analysis was used to estimate the adjusted odds ratios and 95% confidence intervals., Results: Seventy-two controls and 130 patients were analyzed. The PB length, height, and area measurements were significantly lower in the POP group. The perineal mobility in different directions was significantly higher in the POP group. Multivariate analysis demonstrated that the PB area and perineal mobility in the ventral-dorsal and cranio-caudal directions were associated with POP., Conclusions: Our data suggest that a smaller PB area and greater dorsal or caudal mobility are associated with prolapse., Competing Interests: The authors have declared they have no conflicts of interest., (Copyright © 2022 American Urogynecologic Society. All rights reserved.)

Objectives: The aim of this study was to identify the prevalence of peripherally inserted central catheter (PICC) malposition and the influence of guide wire removal on tip location in PICCs and determine whether related factors, including age, sex, side of insertion and brand of catheter, influence the PICC tip location., Setting: Single-centre research institute in China recruiting patients from the hospital., Participants: A total of 837 adult patients with inserted PICCs were recruited from October 2016 to May 2017., Interventions: This was a cross-sectional study aiming to identify the prevalence of PICC malposition and the influence of guide wire removal on tip location in PICCs. A linear regression model and a variance of factorial design analysis were performed. The PICC tip location was documented on a postinsertion chest X-ray. Multivariable analyses were performed based on the following related factors: age, sex, side of insertion and brand of catheter., Results: The tip location moved a mean of 17.4 mm among the 837 included patients. The prevalence of PICC malposition was 83.6% (700/837), while 16.4% (137/837) of PICCs remained in correct location. The mean movement caused by guide wire removal without an adjusted tail end was (-1.95±26.90) mm. The difference between tail end adjustment movement and actual tip position movement in each PICC was (33.0±17.1) mm in type C, which was significantly higher than the findings for type A (12.8±13.3) mm and type B (12.9±12.7) mm., Conclusions: PICC malposition is a frequent event. Different catheter brands were associated with different ranges of movement in tip location after guide wire removal. The age and sex of the patients and the insertion side did not influence the extent of movement., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Acinetobacter baumannii has emerged worldwide as an important opportunistic nosocomial pathogen and has become a major public health concern. In this study, the draft genome sequence of A. baumannii TCM331 (ST208/CC92), a multidrug-resistant (MDR) isolate harbouring the blaOXA-23 gene isolated in China, was determined. The genome of TCM331 was sequenced via Illumina HiSeq™ 2000, and bioinformatics analysis was performed. Important antimicrobial resistance determinants were observed in an estimated genome size of 4,058,691bp with 3838 predicted coding regions. In conclusion, these data might facilitate further understanding of the specific genomic features of MDR A. baumannii in China., (Copyright © 2015 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)