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Surface settlement caused by shallow shield tunneling can occur frequently. Machine variables such as face pressure, tail-void grouting pressure, and grout volume play an essential role in the settlement control of earth pressure balance (EPB) tunnel boring machines (TBMs). Combined with literature review, theoretical derivation, case verification, and numerical simulation, methods were established for adjusting the key parameters, including the face pressure in the plenum chamber, the advance speed of the shield machine, and the rotational speed of the screw conveyor. The grouting volume required to backfill the tail void was calculated according to shield kinematics, a physical model test under high pressure and soil states during excavation,. From the mechanical properties of soil, the function between surface settlement and tail-void grouting pressure based on the Peck formula, stochastic medium theory, and Terzaghi soil arching theory was deduced for the first time. With the increase in grouting pressure, the soil was compressed after the formation of the soil arch, and the process from original settlement to upheaval was also expressed by numerical simulations. In addition, the proposed methods could control the surface settlement effectively and result in more accurate predictions. By comparing the predicted surface settlement to measured data from the Harbin Metro Line 2 project, the adaptability of the proposed methods for the face pressure, tail-void grouting pressure, and grout volume was verified. [ABSTRACT FROM AUTHOR]

In engineering practice, engineers generally treated tuff as a lumpy material with a poorly defined laminated structure and a rock group that was not susceptible to slide failure. Most studies of tuff landslides had focused on small clastic landslides in shallow strata with weathering boundaries and lithologic interfaces as slip surfaces. This paper takes a large-scale, deep-seated tuff landslide on the southeast coast of China as the research project. We used borehole TV imaging and exploration tunnels to confirm the material composition and structural characteristics of the tuff stratum and used exploration tunnels to expose the slip soil directly. Microscopic identification, mineralogical composition analysis, zircon U-Pb isotope dating, and Hf isotope analysis of slip soils collected from the exploration tunnels elucidated the geologic background and genesis of the large- scale deep-seated landslides in the tuff stratum. It was found that the formation of a tuff stratum in the landslide area was caused by multi-volcanic orogeny and multi-phase tectonics. The timing of the melting of the original magma from these volcanic events also differs. During these intervals between eruptions, deposition occurred, and this sedimentary material formed the slip soil. [ABSTRACT FROM AUTHOR]

In the exploration tunnels of the Xiageliao landslide, slide failures were found not only inside the slip soil but also on the contact surface between the slip soil and the tuff. The undisturbed slip soil was collected from the exploration tunnel for testing to explore the pattern of slide failure occurrence. The surfaces of concrete blocks of different shapes were used to simulate slip soil–tuff contact surfaces of different roughness. The shear strength of these contact surfaces with different roughness was tested using a large-scale shear test system and analyzed through comparison with the shear strength of the slip soil. The test results showed that the interface roughness significantly affected the shear strength of the slip soil contact interface and determined the shear failure mode of the slip soil. When the roughness is below a certain level, the shear strength of the contact surface is less than the soil shear strength, and when the roughness reaches a certain level, the shear strength of the contact surface exceeds the strength of the slip soil itself. Thus, the strength of the slip soil itself sometimes differs from the strength of the slip surface. Based on the Moore–Cullen law, the test results found a formula for calculating the contact surface shear strength. These results provide some references for the risk evaluation of landslides. [ABSTRACT FROM AUTHOR]

Mining activities can damage rock masses and easily induce ground collapse, which seriously threatens safe production in mining areas. Micro-seismic systems can monitor rock mass deformation signals in real time and provide more accurate data for rock mass deformation analysis. Therefore, in this study, the waveform characteristics of micro-seismic events induced by ground collapse in the Rongxing gypsum mine were analyzed; the occurrence of these events was introduced on the basis of Fast Fourier Transform, an established Frequency–Time–Amplitude model, in order to put forward the index of energy proportion of the main band. The results showed the following. (1) The seismic sequence type of ground collapse was foreshock–mainshock–aftershocks. The interval between the foreshock and mainshock was longer than that between the mainshock and aftershocks. (2) The deformation corresponding to the foreshock micro-seismic events was mainly that of a small-scale crack. The deformation corresponding to the micro-seismic events during the mainshock was characterized by the gradual development of small-scale cracks, and the development of large-scale cracks accelerated, accompanied by slight rock collapse. The deformation corresponding to the micro-seismic events during the aftershocks showed that almost no small-scale cracks developed, and the large-scale crack development was intense, and accompanied by numerous rock and soil mass collapses. (3) The observed decreasing frequency distribution and energy dispersion can be used as possible precursors of ground collapse. [ABSTRACT FROM AUTHOR]

Landslide susceptibility mapping (LSM) is significant for landslide risk assessment. However, there remains no consensus on which method is optimal for LSM. This study implements a dynamic approach to landslide hazard mapping by integrating spatio-temporal probability analysis with time-varying ground deformation velocity derived from the MT-InSAR (Multi-Temporal InSAR) method. Reliable landslide susceptibility maps (LSMs) can inform landslide risk managers and government officials. First, sixteen factors were selected to construct a causal factor system for LSM. Next, Pearson correlation analysis, multicollinearity analysis, information gain ratio, and GeoDetector methods were applied to remove the least important factors of STI, plan curvature, TRI, and slope length. Subsequently, information quantity (IQ), logistic regression (LR), frequency ratio (FR), artificial neural network (ANN), random forest (RF), support vector machine (SVM), and convolutional neural network (CNN) methods were performed to construct the LSM. The results showed that the distance to a river, slope angle, distance from structure, and engineering geological rock group were the main factors controlling landslide development. A comprehensive set of statistical indicators was employed to evaluate these methods' effectiveness; sensitivity, F1-measure, and AUC (area under the curve) were calculated and subsequently compared to assess the performance of the methods. Machine learning methods' training and prediction accuracy were higher than those of statistical methods. The AUC values of the IQ, FR, LR, BP-ANN, RBF-ANN, RF, SVM, and CNN methods were 0.810, 0.854, 0.828, 0.895, 0.916, 0.932, 0.948, and 0.957, respectively. Although the performance order varied for other statistical indicators, overall, the CNN method was the best, while the BP-ANN and RBF-ANN method was the worst among the five examined machine methods. Hence, adopting the CNN approach in this study can enhance LSM accuracy, catering to the needs of planners and government agencies responsible for managing landslide-prone areas and preventing landslide-induced disasters. [ABSTRACT FROM AUTHOR]

A swivel cable-stayed bridge over the existing railway is a span across the existing railway. The recommended scheme for the main bridge is (128 + 388 + 128) m steel mixed composite beam swivel diagonal pull bridge with span. The cables of the diagonal pull bridge are arranged according to the fanshaped central double cable plane, taking into account the mechanical performance and aesthetics. The bridge structure adopts semi floating system. The concrete swivel diagonal pull bridge is adopted in the comparison scheme. The design of the bridge is three spans and (138 + 268 + 138) m prestressed concrete box girder is adopted. The cables are arranged according to the central double cable plane, and the bridge composition adopts the consolidation system. Considering the needs of bridge operation and maintenance in the later stage of the bridge, when the dead weight of concrete diagonal pull bridge is within the ideal range, the concrete swivel diagonal pull bridge can be preferred. In order to calculate the dead weight of the selected bridge, the author uses the finite element software to model the whole bridge and calculate the weight of the bridge. The results show that the dead weight of the concrete swivel diagonal pull bridge is too large, which has exceeded the maximum bearing capacity of the existing spherical hinge. In order to continue to use the concrete swivel diagonal pull bridge scheme, it is necessary to optimize the design of the concrete swivel diagonal pull bridge scheme.

In order to study the influence of prestress on cantilever deflection and construction linear control of continuous rigid frame bridge in construction stage, this paper introduces the significance of continuous rigid frame bridge’s linear control, the calculation principle and deflection influence analysis of vertical formwork elevation in cantilever construction. According to a specific continuous rigid frame bridge, this paper use the finite element software to simulate and calculate the deflection of prestress to the cantilever construction of continuous rigid frame bridge. The influence of friction coefficient between prestressed steel bundle and bellows and prestress loss on cantilever deflection and construction line control of continuous rigid frame bridge is also analyzed, furtherly brings out the solution to deal with the problems due to the change of prestress.

In this thesis, the numerical models of multi-stages excavation foundation pit with h-shaped double row piles as the retaining structure were built by finite element software PLAXIS 3D with HS small model as the constitutive equation for soil layers, then the numerical models for two different pile layout methods, parallel layout and staggered layout, were calculated, calculation results were compared. The numerical calculation result shows that back row piles stand most load, so they need to be strengthened during the design and construction process; the bending moment of back row piles at the position connecting with beam is the largest, which need to be strengthened; the h-shaped double row piles with staggered layout method is better than the parallel way, which could be used to improve the safety of engineering, as well as achieving economic rationality.

Interest rates frequently exhibit regulated or controlled characteristics, for example, the prevailing zero interest rate policy, or the leading role of central banks in short rate markets. In order to capture the regulated dynamics of interest rates, we introduce the skew constant-elasticity-of-variance (skew CEV) model. We then propose two numerical approaches: an improved finite difference scheme and a piecewise binomial lattice to evaluate bonds and European/American bond options. Numerical simulations show that both of these two approaches are efficient and satisfactory, with the finite difference scheme being more superior. [ABSTRACT FROM AUTHOR]

The frequent and sharp fluctuations in garlic prices seriously affect the sustainable development of the garlic industry. Accurate prediction of garlic prices can facilitate correct evaluation and scientific decision making by garlic practitioners, thereby avoiding market risks and promoting the healthy development of the garlic industry. To improve the prediction accuracy of garlic prices, this paper proposes a garlic-price-prediction method based on a combination of long short-term memory (LSTM) and multiple generalized autoregressive conditional heteroskedasticity (GARCH)-family models for the nonstationary and nonlinear characteristics of garlic-price series. Firstly, we obtain volatility characteristic information such as the volatility aggregation of garlic-price series by constructing GARCH-family models. Then, we leverage the LSTM model to learn the complex nonlinear relationships between the garlic-price series and the volatility characteristic information of the series, and predict the garlic price. We applied the proposed model to a real-world garlic dataset. The experimental results show that the prediction performance of the combined LSTM and GARCH-family model containing volatility characteristic information of garlic price is generally better than those of the separate models. The combined LSTM model incorporating GARCH and PGARCH models (LSTM-GP) had the best performance in predicting garlic price in terms of evaluation indexes, such as mean absolute error, root mean-square error, and mean absolute percentage error. The combined model of LSTM-GARCH provides the best results in garlic price prediction and can provide support for garlic price prediction. [ABSTRACT FROM AUTHOR]

An odometer wheel is used to measure forward distance for a piezoelectric ultrasonic device, and it plays a key role in locating defections. Buckling and skidding are its main problems in applications. Based on a self-developed in-line inspection tool, an odometer wheel was designed according to mechanical design principles. A finite element model on scale of 1 : 1 was built to simulate mechanical performance of the odometer wheel. Results show that the maximum Mises stress under the worst condition is far less than the elastic limit of chosen stainless steel, and deformations of swing arms are slight. Acting forces under different conditions also meet requirements of antiskid. It indicates that the designed object has good performance in terms of structure stability and skid prevention. [ABSTRACT FROM AUTHOR]

Wastes in municipal landfills will release heavy metal cations over a long period of time. Therefore, the objective of this paper was to investigate the effect of copper (Cu) in the leachate from landfill on the swell-shrinking potential of bentonite liner. Copper sulfate solution with 4 different groups of concentrations (0 g/L, 2.5 g/L, 5 g/L, 10 g/L) were added to bentonite for conducting a series of swelling and shrinkage experiments. Then the Does Response model was used to describe the swelling and shrinkage process of bentonite in different copper sulfate solutions and the applicability of the model was evaluated. At the same time, clay mineral analysis experiments (XRD and XRF) were carried out to analyze the variation of interlayer space and element content of montmorillonite. The results show that the swell volume of bentonite decreases with the increase of the concentration of Cu (II). The rate of swelling was high and inversely proportional to the concentration of Cu (II). The shrinkage curve of bentonite could be divided into uniform velocity stage, variable velocity stage, and stable stage. The shrinkage rate at the uniform velocity stage and shrinkage at the stable stage decreased with the increase of the concentration of Cu (II). The model was suitable for describing swelling (or shrinkage) curves with smaller expansibility (or shrinkage). Results of XRD and XRF show that the erosion of Cu (II) led to the decrease of Na+ content in sodium bentonite, and then narrowed interlayer space of montmorillonite. When the solution concentration increases, both values of interlayer space of montmorillonite and Na+ content in sodium bentonite become lower, and that led to swelling and shrinkage of bentonite liner was getting smaller and smaller. [ABSTRACT FROM AUTHOR]

The stability of high rock slopes has become a key engineering geological problem in the construction of important projects in mountainous areas. The original slope stability probability classification (SSPC) system, presented by Hack, has made obvious progress and been widely used in rock slope stability analysis. However, the selection and determination of some evaluation indexes in the original SSPC method are usually subjective, such as intact rock strength and weathering degree. In this study, the SSPC method based on geological data obtained in the prospecting tunnels was presented and applied. According to the field survey and exploration of the prospecting tunnels, the weathering degree of the slope rock mass was evaluated. The empirical equation for the maximum stable height of the slope was applied to the slope stability evaluation in the presented SSPC method. Then, the slope stability probability of numerous cutting slopes in the sandstone unit was evaluated using the presented system. Results of the Geostudio software based on the limited equilibrium analysis of the investigated slopes were compared with the results obtained by the SSPC method. The results indicate that the SSPC method is a useful tool for the stability prediction of high and steep rock slopes. [ABSTRACT FROM AUTHOR]

Anticardiolipin antibody (aCL), an important characterization of antiphospholipid syndrome, shows an intense association with vascular endothelial injury. Hyperoside is a flavonoid extracted from medicinal plants traditionally used in Chinese medicines, displaying anti-inflammatory, anti-cancer, and anti-oxidative properties in various diseases. Recent studies have shifted the focus on the protective effects of hyperoside on vascular endothelial injury. However, little is known about the mechanisms involved. In the present study, we investigated the effect of hyperoside on aCL-induced injury of human umbilical vein endothelial cells (HUVECs) in vitro. Our data illustrated that aCL induced HUVEC injury via inhibiting autophagy. Hyperoside reduced aCL-induced secretion of proinflammatory cytokines IL-1β and IL-8 and endothelial adhesion cytokines TF, ICAM1, and VCAM1 in HUVECs. Additionally, hyperoside activated autophagy and suppressed the mTOR/S6K and TLR4/Myd88/NF-κB signaling transduction pathways in aCL-induced HUVECs. To the best of our knowledge, this is the first study to investigate the effect of hyperoside on aCL-induced injury, as well as offer insights into the involved mechanisms, which is of great significance for the treatment of antiphospholipid syndrome. [ABSTRACT FROM AUTHOR]

In this paper, a discrete-time framework is proposed to value power exchange options with counterparty default risk, where counterparty risk is considered in a reduced-form setting and the variance processes of the underlying assets are captured by GARCH processes. In addition, the proposed model allows for the correlation between the intensity of default and the variances of the underlying assets by breaking down the total risk into systematic and idiosyncratic components. By dint of measure-change techniques and characteristic functions, we obtain the closed-form pricing formula for the value of power exchange options with counterparty default risk. Finally, numerical results are presented to show the power exchange option values. [ABSTRACT FROM AUTHOR]

Cu(BTC)-MOF catalyzed one-pot, three-component reaction of terminal alkynes, halides and sodium azide to form 1,4-disubstituted-1,2,3-triazoles was investigated. It was conducted in methanol under room temperature with good to excellent product yields. The Cu(BTC)-MOF catalyst could be easily recovered by filtration and be reused at least three recycles with no significant decrease in the yield. The method was demonstrated to be a truly green process with sustainability and economics. [ABSTRACT FROM AUTHOR]

In this paper, we investigate executive stock options with endogenous departure and time-varying variances. We use a “Generalized Autoregressive Conditional Heteroskedasticity” process to capture the variance process of the log stock price. In addition, we take into consideration the departure risk of the executive and assume that the probability of remaining employed has a power form of stock price ratios. After deriving the closed-form pricing formulae of executive stock options, we illustrate the effects of the departure risk on the values of executive stock options. [ABSTRACT FROM AUTHOR]

Background. Antihypertensive drug use is inconsistently associated with the risk of dementia, Alzheimer’s disease, cognitive impairment, and cognitive decline. Therefore, we conducted a meta-analysis of available prospective cohort studies to summarize the evidence on the strength of these relationships. Methods. Three electronic databases including MedLine, Embase, and the Cochrane Library were searched to identify studies from inception to April 2017. Only prospective cohort studies that reported effect estimates with corresponding 95% confidence intervals (CIs) of dementia, Alzheimer’s disease, cognitive impairment, and cognitive decline for antihypertensive drug use versus not using antihypertensive drugs were included. Results. We included 10 prospective cohort studies reporting data on 30,895 individuals. Overall, participants who received antihypertensive drugs had lower incidence of dementia (relative risk [RR]: 0.86; 95% CI: 0.75–0.99; p=0.033), while there was no significant effect on the incidence of Alzheimer’s disease (RR: 0.83; 95% CI: 0.64–1.09; p=0.154), cognitive impairment (RR: 0.89; 95% CI: 0.57–1.38; p=0.596), and cognitive decline (RR: 1.11; 95% CI: 0.86–1.43; p=0.415). Further, the incidence of Alzheimer’s disease might be affected by antihypertensive drug use in participants with specific characteristics. Conclusions. Antihypertensive drug use was associated with a significantly reduced risk of dementia, but not with the risk of Alzheimer’s disease, cognitive impairment, and cognitive decline. [ABSTRACT FROM AUTHOR]