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Scientific risk assessment of dammed lakes is vitally important for emergency response planning. In this study, based on the evolution process of the disaster chain, the logic topology structure of dammed lake risk was developed. Then, a quantitative risk assessment model of dammed lake employing Bayesian network is developed, which includes the three modules of dammed lake hazard evaluation, outburst flood routing simulation, and loss assessment. In the proposed model, the network nodes of each module were quantified through statistical data, empirical model, logical inference, and Monte Carlo method. The failure probability of a dammed lake, and the losses of life and property because of its breaching were calculated. This can be multiplied to assess the risk a dammed lake imposes after the uniformization of each loss type. Based on the socio-economic development and longevity statistics of dammed lakes, a risk level classification method for dammed lakes is proposed. The Baige dammed lake, which emerged in China in 2018, was chosen for a case study and risk assessment was conducted. The calculated results showed that the comprehensive risk value of Baige dammed lake is 0.7339 under the condition without manual intervention, identifying it as the extra-high level according to the classification. These results are in accordance with the actual condition, which corroborates the reasonability of the proposed model. This model can quickly and quantitatively evaluate the overall risk of a dammed lake and provide a reference for decision-making in a rapid emergency response scenario.

Soil erosion and water loss are serious problems on the rocky desertification slopes in the karst dynamic system of southwest China. The lack of soil and shortage of water restrict the ecological restoration of the regional slopes and utility of water resources. Therefore, a new slab trench capable of storing soil and water in layers on rocky desertification slopes is introduced in this paper to promote vegetation restoration. To explore the water-storing and -holding capacity of the new type of vegetated slab trench, five groups of model experiments were carried out on the vegetated slab trench under different rainfall intensities and different numbers of plants. Under rainfall and then following dry conditions, the effects of rainfall intensity and the number of plants on the water-storing and -holding capacity of vegetated slab trench models were compared and analyzed. Water-storing and -holding capacity was further explored in three groups of models with single planting or combinations of plants including water stored only in succulent root plant, only in succulent stem plant, or in mixed plants. The test results show that the new type of vegetated slab trench can effectively help to store and hold water. In the rainfall period, due to the runoff of the rainfall not being considered, the greater the rainfall intensity, the higher the water storage efficiency; the more vegetation implanted, the greater the blocking effect of the plant canopy during falling rainwater, and the more reduction is induced on the water storage efficiency of the vegetated slab trench. In the following dry period, both the succulent root plant and succulent stem plant have strong water storage capacity, but the succulent root plant has a stronger capacity for water storage. The growth status of the mixed plants was better than that of single planting, which may be due to the water complementarities between the succulent root plant and succulent stem plant in a mixed planting manner. This study is important for solving the problem of soil erosion and water loss in rocky desertification slopes, and it helps to restore the ecological environment of the area.

Background. Rab8A has been reported as an oncogenic gene in breast and cervical cancer. However, the function and molecular mechanism of Rab8A in esophagus cancer has not been reported. Methods. Rab8A expression was detected by qPCR and western blotting assays, small interference RNA (siRNA) was applied to reduce Rab8A expression, and the biological behaviors of esophagus cancer cells were estimated by cell counting kit-8, colony formation, and transwell and western blotting assays. The transcriptional factor of Rab8A was verified by dual-luciferase assay and chromatin immunoprecipitation assay. The protein expression of key genes in the Wnt/β-catenin signaling pathway was determined by western blotting assay. M435-1279 was used to suppress the Wnt/β-catenin signaling pathway. Results. A significant increase of Rab8A expression has been found in esophagus cancer cells. Knockdown of Rab8A suppressed the viability, colony formation, migration, and invasion abilities of esophagus cancer cells and induced apoptosis. PEA3 transcriptionally regulated Rab8A expression and promoted the viability, colony formation, migration, and invasion abilities of esophagus cancer cells and blocked apoptosis, which were diminished by si-Rab8A transfection. Additionally, the expression levels of key genes related to the Wnt/β-catenin signaling pathway were strengthened by PEA3 overexpression, which were reduced by si-Rab8A transfection. M435-1279 treatment significantly reduced the viability and colony formation of esophagus cancer cells. Conclusions. The data showed that Rab8A was transcriptionally regulated by PEA3 and promoted the malignant behaviors of esophagus cancer cells by activating the Wnt/β-catenin pathway. The above results indicated that Rab8A may be considered as a promising biomarker for diagnosis and precision treatment in esophagus cancer.

A hypoplastic constitutive model is proposed to model the cementation-induced enhanced stiffness, strength and dilative behavior of cemented sand and gravel materials. The model is based on the original equations proposed by Gudehus and Bauer (1996) and is extended on the basis of the concept of geometrical constraints due to cementation. The novelty of the model is twofold. First, a damage-dependent additional void ratio term is added to the original equations for the maximum, minimum and critical void ratios to account for the geometrical constraints. As a result, the two-dimensional characteristic state lines are extended to three-dimensional characteristic state surfaces. Second, a new damage factor is introduced to the constitutive equation to reflect the effect of cementation on the peak strength, and the so-called barotropy component of the stiffness factor is reformulated. Both the additional void ratio and the damage factor are related to the damage process of the inter-particle bonds, and a strain-driven damage equation is proposed based on the results of previous discrete element simulations. The model is used to reproduce triaxial experiments on a cemented dense gravel and a cemented loose sand. It is capable of capturing most of the important features of cemented granular materials. The work described in this study demonstrates the capability of hypoplasticity in modeling the complex behavior of structured soils.

The accurate and rapid prediction of landslide dam stability is of great significance for emergency response planning. However, current rapid prediction methods for the landslide dam cannot quantitatively consider the influence of landslide debris grain size distribution. A database was established based on 1434 documented historical landslide dams, including formed-unstable and formed-stable cases from around the world. The logistic regression method was utilized to develop new methods for the rapid prediction of landslide dam stability, which can consider the morphological characteristics and particle composition of the landslide dams as well as the hydrodynamic conditions of the upstream dammed lake. According to the available information on landslide debris particle composition, the newly proposed rapid prediction methods were classified as either detailed or simplified based on 27 and 150 cases, respectively. Based on the database, several typical methods for the rapid prediction of landslide dam stability were chosen to compare with the newly proposed methods. The performances of each method testify to the rationality of the new methods.

Novel Cu-nanoparticles (NPs) embedded in porous carbon materials (Cu@C-x) were prepared by one-pot pyrolysis of metal–organic frameworks (MOF) HKUST-1 at different temperatures. The obtained material Cu@C-x was used as a cost-effective catalyst for the hydrogenation of nitrobenzene using NaBH4 as the reducing agent under mild reaction conditions. By considering the catalyst preparation and the catalytic activity, a pyrolysis temperature of 400 °C was finally chosen to synthesize the optimal catalyst. When the aromatic nitro compounds with reducible groups, such as cyano, halogen, and alkyl groups, were tested in this catalytic hydrogenation, an excellent selectivity approaching 100% was achieved. In the recycling experiment, a significant decrease in nitrobenzene conversion was observed in the third cycle, mainly due to the very small amount of catalyst employed in the reaction. Hence, the easily prepared and cost-effective Cu@C-400 catalyst fabricated in this study demonstrates potential for the applications in selective reduction of aromatic nitro compounds. The catalyst Cu@C-400 exhibited 100 % conversion and high selectivity for the hydrogenation of industrially relevant nitroarenes.

On October 10 and November 3, 2018, two successive landslides occurred at Baige village, the border between Sichuan Province and Tibet Autonomous Region, in China, which totally dammed the Jinsha River on both occasions. Due to the rapid rise in water level in the “10·10” dammed lake, on October 12, the landslide dam breached naturally with the peak breach flow of about 10,000 m3/s. The residual landslide dam was stacked by the subsequent landslide on November 3, resulting in an even larger dammed lake. Fortunately, the height from the water level in the lake to the dam crest made it possible to construct a spillway to drain the water in the dammed lake to a relatively low level. On November 12, the drainage process began with the peak breach flow of 31,000 m3/s. In this study, based on the detailed records of the breach process of the “11·03” Baige landslide dam and using the developed physically based numerical method, a back analysis was conducted. The numerical method was developed based on the overtopping-induced breach mechanism of landslide dams. An iterative time step algorithm was used to simulate the breach evolution and the hydrograph coupling. The major highlights of the numerical method are the consideration of the breach mechanism of landslide dam, such as the breach morphology evolution process along the streamwise and transverse directions, as well as the variation of soil erodibility with depth and the influence of the presence and absence of a spillway. Comparison of the measured and the calculated results indicated that the numerical method developed in this study can reproduce reasonable breach hydrograph and breach evolution process. The sensitivity analysis showed that the soil erodibility coefficient and the residual dam height significantly influenced the landslide dam breaching process. In addition, it was determined that constructing a spillway before landslide dam breaching is an effective flood hazard mitigation measure for large dammed lakes. However, the availability of the construction conditions and the shape of the spillway should be judged comprehensively according to the rising rate of water level and construction capacity.

In dense urban areas, conventional GNSS does not perform satisfactorily, sometimes resulting in errors of tens of metres. This is due to the blocking, reflection and diffraction of GNSS satellite signals by obstructions such as buildings and moving vehicles. The 3D mapping data of buildings can be used to predict which GNSS signals are line-of-sight (LOS) and which are non-line-of-sight (NLOS). These data have been shown to greatly improve GNSS performance in urban environments. Location-based services typically use single-epoch positioning, while all pedestrian and vehicle navigation applications use filtered solutions. Filtering can reduce the impact of noise-like errors on the position solution. Kalman filtering-based solutions have been adopted as one of the standard algorithms for GNSS navigation in many different products, and particle filtering has been demonstrated by several research groups. This paper mainly investigates the performance of different filtering algorithms combined with 3D-mapping-aided (3DMA) techniques. In addition to the Kalman filter and particle filter, the grid filter is also considered. In contrast to a particle filter, the hypotheses of a grid filter are uniformly distributed (forming a grid), but with different likelihoods, which better fits the physics of the problem. At the same time, this allows the current UCL’s single-epoch 3DMA GNSS positioning algorithm to be easily extended to multi-epoch situations. This paper then compares the performance of these continuous positioning algorithms in urban environments. The datasets used for testing include pedestrian and vehicle navigation data, covering two main application scenarios that often appear in cities. Pedestrian navigation data is static, and was collected in the City of London using a u-blox EVK M8T GNSS receiver. The vehicle navigation data consists of GPS and Galileo measurements, collected in Canary Wharf by a trials van with a Racelogic Labsat 3 GNSS front end. Subsequently, these data are fed into several single- and multi-epoch filtering algorithms, including single-epoch conventional GNSS, single-epoch 3DMA GNSS, conventional extended Kalman Filter (EKF), conventional particle filter (PF), 3DMA GNSS particle filter (PF), and 3DMA GNSS grid filter (GF). The results show that filtering has a greater impact on the results of mobile positioning with significant movement compared to static positioning. In vehicle tests, the conventional multi-epoch GNSS algorithms improve positioning accuracy by more than 40% compared to single-epoch GNSS, whereas in static positioning they deliver a limited improvement. 3DMA GNSS significantly improves positioning accuracy in the denser environments, but provides little benefit in more open areas. The 3DMA GNSS techniques and the filtering algorithms benefit each other. The former provides the latter with a better position solution at the measurement update step, while the latter in turn repays the former with a better initial position and a smaller search area. In vehicle tests at Canary Wharf, the 3DMA GNSS filtering reduces the overall solution error by approximately 50% and 40% compared to the single-epoch 3DMA GNSS and filtered conventional GNSS, respectively. Thus, multi-epoch 3DMA GNSS filtering should bring maximum benefit to mobile positioning in dense environments. The results from both datasets also confirm that the performance of 3DMA GNSS particle filtering and grid filtering are similar in terms of positional accuracy. In terms of efficiency, 3DMA GNSS grid filtering uses fewer particles to achieve the same coverage of the search area as particle filtering.

An elastoplastic constitutive model that takes into account the stress–strain relationship and creep-induced hardening behavior of rockfill materials is proposed in light of previous experimental observations. It is assumed that the mechanical response during loading and the final amounts of creep strains under a constant stress state are independent of the strain rate. The focus of the proposed model is the coupling effect between loading and creep, including the influence of loading history on subsequent creep strains and the influence of creep history on subsequent loading behavior. An extended yield function, which allows flexible control over the shape of yield surfaces, is used not only to distinguish among loading, unloading, and neutral loading, but also to manipulate the creep-induced hardening using a plastic strains–based hardening parameter. A stress-dependent dilatancy equation is used, instead of a plastic potential function, to define the directions of plastic strains during loading. The hardening law is established based on three different types of experimental results. Only routine experiments are required for calibration of model parameters, and the model can be used in a reduced form according to the available test results. The model is verified using typical experimental data and is found to be capable of capturing important behavior of rockfill materials, such as pressure-dependent strength, shear contraction and dilation, and creep-induced stiffening.

Based on model tests of earthen dam breach due to piping failure, a numerical model was developed. A key difference from previous research is the assumption that the cross-section of the pipe channel is an arch, with a rectangle at the bottom and a semicircle at the top before the collapse of the pipe roof, rather than a rectangular or circular cross-section. A shear stress-based erosion rate formula was utilized, and the arched pipe tunnel was assumed to enlarge along its length and width until the overlying soil could no longer maintain stability. Orifice flow and open channel flow were adopted to calculate the breach flow discharge for pressure and free surface flows, respectively. The collapse of the pipe roof was determined by comparing the weight of the overlying soil and the cohesion of the soil on the two sidewalls of the pipe. After the collapse, overtopping failure dominated, and the limit equilibrium method was adopted to estimate the stability of the breach slope when the water flow overtopped. In addition, incomplete and base erosion, as well as one- and two-sided breaches were taken into account. The USDA-ARS-HERU model test P1, with detailed measured data, was used as a case study, and two artificially filled earthen dam failure cases were studied to verify the model. Feedback analysis demonstrates that the proposed model can provide satisfactory results for modeling the breach flow discharge and breach development process. Sensitivity analysis shows that the soil erodibility and initial piping position significantly affect the prediction of the breach flow discharge. Furthermore, a comparison with a well-known numerical model shows that the proposed model performs better than the NWS BREACH model. Keywords: Earthen dam, Piping failure, Overtopping failure, Breach flow, Numerical modeling, Sensitivity analysis

A green economy is the current trend of sustainable development for the global economy. Using Chinese A-share listed enterprises from 2010 to 2020, this study examines how board gender diversity affects green innovation. Results show that board gender diversity significantly promotes the number and quality of green innovations and that R&D and governments support, as essential intermediary mechanisms have positive effects on the relationship between female directors and green innovation. Moreover, heterogeneous analyses show that high levels of ESG, gender diversity of directorial boards of state-owned enterprises, and large enterprises have a more significant role in promoting green innovation. The study provides empirical evidence for the development of green innovation and theoretical support for the transformation of corporate strategic thinking with more women participating in executive decision-making.

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) has spread rapidly throughout the world. SARS-CoV-2 is an enveloped, plus-stranded RNA virus with a single-stranded RNA genome of approximately 30,000 nucleotides. The SARS-CoV-2 genome encodes 29 proteins, including 16 nonstructural, 4 structural and 9 accessory proteins. To date, over 1,228 experimental structures of SARS-CoV-2 proteins have been deposited in the Protein Data Bank (PDB), including 16 protein structures, two functional domain structures of nucleocapsid (N) protein, and scores of complexes. Overall, they exhibit high similarity to SARS-CoV proteins. Here, we summarize the progress of structural and functional research on SARS-CoV-2 proteins. These studies provide structural and functional insights into proteins of SARS-CoV-2, and further elucidate the daedal relationship between different components at the atomic level in the viral life cycle, including attachment to the host cell, viral genome replication and transcription, genome packaging and assembly, and virus release. It is important to understand the structural and functional properties of SARS-CoV-2 proteins as it will facilitate the development of anti-CoV drugs and vaccines to prevent and control the current SARS-CoV-2 pandemic.

Simulation of dam breach process has significant influence on the evaluation of consequence of dam breach flood. In this study, research progresses on the numerical modeling of earth-rock dams’ breach process are summarized, especially the latest research results of the author’s research team in recent years. However, there still has a considerable gap in the versatility of computer software and visualization technology of dam breaching process. It is suggested that more efforts should be made in the future to study the detailed physically based numerical model for core dam and concrete face rockfill dam; further, more attention should be paid to the application of visualization technology in dam breach process simulation. Finally, the universal and friendly visualization computer software that can accurately simulate the dam failure process and flood routing for earth-rock dams is sorely needed.

Conventional GNSS positioning in dense urban areas exhibits errors of tens of meters due to non-line-of-sight (NLOS) reception and multipath interference. Inertially-aided extended coherent integration within the GNSS receiver, as in the case of supercorrelation or S-GPS/GNSS, mitigates these effects by making the receiver more sensitive to directly received signals than reflected signals whenever the receiver is moving. This reduces multipath interference and makes NLOS signals easier to detect using signal-to-noise measurements. 3D-mapping-aided (3DMA) GNSS uses predictions of which signals are NLOS to enhance the positioning algorithms. 3DMA GNSS ranging algorithms can be combined with shadow matching, which uses the signal-tonoise measurements. Both supercorrelation and 3DMA GNSS can improve positioning accuracy in dense urban areas by more than a factor of two. As supercorrelation takes place at the receiver signal processing stage while 3DMA GNSS operates at the positioning algorithm stage, the two techniques are potentially complementary. This paper therefore investigates the benefits of combining them. GNSS signals were recorded using a Racelogic Labsat 3 GNSS front end on a trials van in the Canary Wharf area of London and subsequently processed to generate conventional and supercorrelated ranging and signal-to-noise measurements from the GPS and Galileo satellites. These are then input to several different positioning algorithms, including conventional positioning, shadow matching and likelihood-based 3DMA ranging and a combination of shadow matching and likelihood-based 3DMA ranging. Single-epoch positioning results using code-only pseudo-ranges clearly demonstrate the benefit of supercorrelation with position errors using S-GNSS measurements 40% smaller than those using conventional least-squares positioning techniques. 3DMA GNSS improves the position accuracy by about 25% in the denser environments, but does not bring any benefits in the more open areas. When supercorrelation is combined with filtered carrier-smoothed pseudo-ranges using outlier detection to reject code components that inconsistent with the carrier-based component, the least-squares position errors are reduced by a factor of 5.7 in the densest of environments and a factor of 3.5 elsewhere. With these filtered measurements, 3DMA GNSS techniques have little impact on the positioning accuracy. Thus, 3DMA GNSS techniques are likely to be more useful for snapshot positioning techniques and potentially for the initialization of filtered solutions than for continuous positioning.

Using the difference-in-differences method, this study investigates the impact of bank lending intervention on firm innovation. We find that bank lending intervention significantly hampers R&D investment of firms in overcapacity industries. Moreover, policy intervention significantly reduces bank lending but increases the firms’ trade credit as well as the financing constraints of firms in overcapacity industries. Furthermore, bank lending intervention reduces the efficiency of credit allocation, an outcome which is attributed to its preference for politically connected firms rather than higher-efficiency ones.

The present study focuses on the breaching process and failure of barrier dams due to overtopping. In this work, a series of centrifugal model tests is presented to examine the failure mechanisms of landslide dams. Based on the experimental results, failure process and mechanism of barrier dam due to overtopping are analyzed and further verified by simulating the experimental overtopping failure process. The results indicate that the barrier dam will develop during the entire process of overtopping in the width direction, whereas the breach will cease to develop at an early stage in the depth direction because of the large particles that accumulate on the downstream slope. Moreover, headcut erosion can be clearly observed in the first two stages of overtopping, and coarsening on the downstream slope occurs in the last stage of overtopping. Thus, the bottom part of the barrier dam can survive after dam breaching and full dam failure becomes relatively rare for a barrier dam. Furthermore, the remaining breach would be smaller than that of a homogeneous cohesive dam under the same conditions.

Landslide dams have a high risk of overtopping failure compared to that of artificial dams. In this study, based on dam morphological characteristics, field investigations, and model tests,...

In order to study the failure mechanism of barrier dam overtopping, centrifugal model tests of dam failure were conducted in this research. A calculation method of rectangular weir flow in the centrifugal field was derived. The process and mechanism of barrier dam overtopping were intensively analyzed. They were further verified by the breach flow curve and the development curve of the breach top width acquired from model tests. Results showed that the barrier dam breach developed during the entire process of overtopping in the width direction. The development of the barrier dam breach in the depth direction, however, ceased at an earlier time on account of the large particles accumulated in the downstream slope. Moreover, coarsening in the downstream slope could be clearly observed in the last stage of overtopping. Thus, it was concluded that the bottom part of the barrier dam could survive after dam breaching and that a full dam failure is relatively rare for a barrier dam. Furthermore, the size of the remaining breach would be less than that of a homogeneous earth dam under the same conditions.

Based on the interface theory, taking the corresponding surface of the yielding depth of debris flows as the interface, the viscous debris flows can be divided into the ideal fluid and the Bingham ...

As a production of natural process, the barrier dam has its own features, and is easily to fail due to overtopping. Based on the breach mechanism revealed by small-scale model tests and the draining case of Tangjiashan Barrier Lake, a numerical breach model for barrier dam due to overtopping failure is put forward. In terms of the geometrical characteristics, physical and mechanical properties of barrier dam, a unified approach is developed to model the evolution of breaches in the dam crest and downstream slope, as well as the morphological change of the barrier dam in streamwise. Furthermore, different failure modes, such as one- and two-sided erosion, incomplete and base erosion are taken into account. The draining of Tangjiashan Barrier Lake is adopted to testify the present model, and the comparison of measured and calculated results indicates the rationality of the present model with the relative errors are less than 10% for peak discharge, final breach widths, and time to peak; in addition, the calculated breach discharge hydrograph and the changing process of water level are in accord with the measured data. The sensitivity analysis shows that the residual dam height after breaching and soil erodibility affect the breach flow prediction of the barrier dam significantly, whereas the one- or two-sided breach mode is less sensitive.

Based on the breach mechanism of the core dam due to overtopping failure, a simplified physically-based model has been proposed in this study. A hydraulic method was used to predict the initial scour position for high dam. A time averaged erosion equation was adopted to simulate the backward erosion of dam's shoulder. The broad-crested weir equation was adopted to calculate the breach flow discharge. Furthermore, the sliding or overturning failure was adopted as the key mechanism for the core, which was judged based upon numerical analysis. The results showed that the model allowed for one-side and two-side erosions, as well as for the dam base erosion. An iterative method is developed to simulate the coupling process of soil and water at each time step. The failure of Banqiao dam was used as an illustrative example, as detailed data about its failure is available in literature. Nine core dam breach cases, caused by overtopping, were studied to verify the model. Meanwhile, three typical parametric breach models were chosen to compare the results with those obtained from the proposed model. The back analysis and comparison results demonstrated that the proposed physically-based model not only provided satisfactory results, but also performed better and produced more detailed results than the parametric model. Moreover, the calculated results indicated that the overturning failure was the dominating failure mode for the core failure.

A simplified physically-based model was developed to simulate the breaching process of the Gouhou concrete-faced rockfill dam (CFRD), which is the only breach case of a high CFRD in the world. Considering the dam height, a hydraulic method was chosen to simulate the initial scour position on the downstream slope, with the steepening of the downstream slope taken into account; a headcut erosion formula was adopted to simulate the backward erosion as well. The moment equilibrium method was utilized to calculate the ultimate length of a concrete slab under its self-weight and water loads. The calculated results of the Gouhou CFRD breach case show that the proposed model provides reasonable peak breach flow, final breach width, and failure time, with relative errors less than 15% as compared with the measured data. Sensitivity studies show that the outputs of the proposed model are more or less sensitive to different parameters. Three typical parametric models were compared with the proposed model, and the comparison demonstrates that the proposed physically-based breach model performs better and provides more detailed results than the parametric models. Keywords: Concrete-faced rockfill dam, Physically-based breach model, Parametric breach model, Sensitivity analysis, Gouhou CFRD