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Noise reduction is a key process in digital image detection technology for concrete cracks and bug-holes. In this study, the threshold range of the flood-filling noise reduction algorithm was investigated experimentally. Surface cracks and bug-holes in RC bridge concrete were detected using mobile terminal images based on the flood-filling noise reduction algorithm. The results showed that the error range was within 10% when threshold range Θ was confined in [60, 80] as the crack width was from 0.1 mm to 2 mm. It is suitable that the threshold range Θ was selected as 70 while the measured crack width range was 0.2 mm to 2 mm. However, by reducing the values of the threshold range Θ to 50, the miscalculation was obviously eliminated. The influences of reducing values of the threshold range on bug-holes of the equivalent diameter and area were not significant. It is suitable that the threshold range Θ was elected on 50 to detect bug-holes in the concrete surface. The threshold range can be selected as a suitable value for the detection of cracks and bug-holes in order to reduce noise. [ABSTRACT FROM AUTHOR]

The vacuum preloading method is commonly used to improve soft soils; however, it has rarely been studied from the perspective of energy consumption. The work done by the vacuum pump in the vacuum system can be consumed in various ways, including seepage consolidation of soil, water discharge along prefabricated vertical drains and horizontal drainage system (i.e. sand blanket or horizontal pipes), extraction of the air sealed in the drainage system and air leakage from the atmosphere. Equations governing these aspects of energy consumption were derived in this study. A theoretical model of the energy consumption of the vacuum preloading method was established and then solved to quantify the specific forms of energy consumption. Theoretical predictions and laboratory results demonstrate that the energy consumptions of seepage consolidation and water discharge are negligibly small compared with the total work by the vacuum pump, and most of the work done by the vacuum pump in the vacuum system is consumed during the extraction of leaked-in air. [ABSTRACT FROM AUTHOR]

Vacuum preloading is a commonly adopted method for improving soft ground. During the preloading period, the applied vacuum pressure is constant or multistaged, implying that the vacuum pump must work continuously with constant or increasing operating power. To reduce the energy consumption of the vacuum pump, a new loading strategy of cyclic vacuum loading was proposed in this study, whereby the pump is periodically switched on and off, and hence the vacuum pressure ascends and descends accordingly. To guide the design of cyclic vacuum preloading, a large-strain radial consolidation theory incorporating the shifting of the consolidation status of ground soil from normally consolidated to overconsolidated (and vice versa) was established in the present study. Based on the established theory, the treatment effects of cyclic vacuum loading can be quantitatively determined, including the ground settlement and the degree of consolidation, while the energy consumption can be simply determined by multiplying the power by the operating time of the vacuum pump, which works only during the ascending stage of cyclic vacuum pressure. Two cases of the cyclic vacuum preloading strategy were evaluated herein, that is, the complete cyclic vacuum loading and combined cyclic/constant vacuum loading cases. Finally, experimental tests were conducted to demonstrate the energy-saving effect of cyclic vacuum preloading. Compared to the conventional vacuum preloading strategy (i.e., constant vacuum pressure), the energy consumption of the cyclic vacuum loading strategy can be drastically reduced (80% reduction), while the treatment effects remain basically unaffected. [ABSTRACT FROM AUTHOR]

The clogging induced by particle transport is often mentioned in the practice of vacuum preloading, but the percolation behavior of soft clay under negative pressure is still not clear. To understand this, the percolation behavior was investigated using an artificial paste of silica sand and kaolinite under different hydraulic pressures. The hydraulic conductivity under positive pressure (90 kPa) was about twice as high as that of negative pressure (−90 kPa). However, the transport capacity and leached particle size under negative pressure were more significant than those under positive pressure, despite the same tendency of the porosity under the positive or negative pressure. This is an interesting and paradoxical finding, suggesting complexity accompanying the erosion and clogging under the nominal hydraulic gradient, where a higher concentration of the hydraulic gradient occurs under negative pressure. The percolation under negative pressure––a self-adaptive process––included three elements: (1) the colloidal transport of clay minerals; (2) colloid accumulation and clogging in the seepage channel close to the outlet; and (3) a gradient concentration close to the outlet. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to explore the evolutionary pattern of discussion topics over time in an online depression self-help community. Design/methodology/approach: Using the Latent Dirichlet Allocation (LDA) method, the authors analyzed 17,534 posts and 138,567 comments posted over 8 years on an online depression self-help group in China and identified the major discussion topics. Based on significant changes in the frequency of posts over time, the authors identified five stages of development. Through a comparative analysis of discussion topics in the five stages, the authors identified the changes in the extent and range of topics over time. The authors discuss the influence of socio-cultural factors on depressed individuals' health information behavior. Findings: The results illustrate an evolutionary pattern of topics in users' discussion in the online depression self-help group, including five distinct stages with a sequence of topic changes. The discussion topics of the group included self-reflection, daily record, peer diagnosis, companionship support and instrumental support. While some prominent topics were discussed frequently in each stage, some topics were short-lived. Originality/value: While most prior research has ignored topic changes over time, the study takes an evolutionary perspective of online discussion topics among depressed individuals. The authors provide a nuanced account of the progression of topics through five distinct stages, showing that the community experienced a sequence of changes as it developed. Identifying this evolutionary pattern extends the scope of research on depression therapy in China and offers a deeper understanding of the support that individuals with depression seek, receive and provide online. [ABSTRACT FROM AUTHOR]

Based on undrained cyclic simple shear tests conducted on coastal tidal soft soil under various conditions of cyclic stress ratios and moisture contents, this study investigated the influence of these factors on the dynamic properties of the soil. The findings indicated that with increasing moisture content and stress cycle ratio, the stress–strain hysteresis loop gradually expanded, resulting in a higher strain difference and a transition from a dense to a sparse curve pattern. Moreover, the symmetry of the hysteresis loop was lost in the later stages of shearing. With an increase in the number of cycles, the cumulative shear strain gradually increased, and the increase in the cyclic ratio of water content to stress reduced the number of cyclic shear cycles required to achieve failure, thereby accelerating the soil's failure rate. A predictive formula was developed based on the experimental results to estimate the failure cycles as a function of the cyclic stress ratio and moisture content. Furthermore, the softening index decreased gradually with an increasing number of cycles, and a higher moisture content and cyclic stress ratio accelerated the soil's softening process. It was observed that under the conditions of optimal moisture content, the soil exhibited a slower softening rate during the initial stage of shearing. [ABSTRACT FROM AUTHOR]

The geotechnical tube technology has been widely used in the dewatering treatment of high-water-content slurries, such as engineering waste muds, mine water sludges, and dredging slurries. However, the existing engineering practice adopting the traditional geotextile tubes is characterized by low efficiency and difficult quality control. To address these issues, a new approach was developed by combining the geotextile tubes and vacuum preloading technology. In this method, several plastic drain boards were embedded in a geotextile tube as prefabricated horizontal drains (PHDs), and a vacuum was applied to promote drainage. The effectiveness of the proposed method was verified by a comparison test. A two-dimensional plane-strain analytical consolidation problem with a distributed drainage boundary was then formulated and solved to predict the consolidation process of soil in a vacuum preloaded geotextile tube. The analytical solution was validated against the results of a pilot field test, and then the influence of PHD spacing on the consolidation process was also discussed. Compared to the traditional geotextile tubes, the approach proposed in this paper promises good applicability and can effectively shorten the treatment time by 73.3% and reduce the water content of treated soils by 51.9%. [ABSTRACT FROM AUTHOR]

Vacuum preloading combined with prefabricated vertical drains is a widely used system for improving soft clay-dredged slurry deposits. However, the influence of the initial water content on clogging is not yet fully understood. In this study, laboratory model tests were conducted on slurry with initial water contents of 106%, 133%, and 159% during vacuum preloading. The process of vacuum preloading was monitored from the perspectives of discharged water volume, pore water pressure, as well as the displacement and strain profile of soil patches by using the novel particle image velocimetry (PIV) technique. The results showed that the clogging formation process could be divided into three stages based on the water discharge rate: rapid formation, transition, and slow formation. An increase in initial water content resulted in a larger horizontal displacement, leading to a thinner and denser clogging zone with lower permeability coefficients and a reduced rate of pore pressure dissipation. Empirical equations for the thickness of the clogging zone versus time were proposed using the PIV technique, providing a reference for theoretical consolidation calculations and making the calculations more practical by considering the variation of the clogging zone during vacuum preloading. [ABSTRACT FROM AUTHOR]

This paper develops a hierarchical Bayesian model (HBM) that integrates the physical knowledge and the test data to predict the small-strain shear modulus Gmax for a target sand type. The limited target-specific data are combined with the abundant generic data through a hierarchical structure so that the variability of Gmax within one sand type and across different sand types can be captured. The hyperparameters that characterize the same underlying distribution of physical model parameters across all the sand types are first estimated from the abundant generic data. The model parameters for the new sand type are then updated as the limited site-specific data become available. The approach is illustrated using a generic database and two real examples not covered by the generic database. Multiple possible hierarchical models are compared in terms of model complexity and goodness-of-fit. The results show that the hierarchical modeling of small-strain shear modulus data is reasonable and necessary. The hierarchical model can provide less biased and more accurate predictions of Gmax compared to the commonly used complete pooling model, especially in cases where the site-specific data are quite different from the overall average of the generic database. [ABSTRACT FROM AUTHOR]

Canine influenza can be caused by a variety of influenza A viruses, including equine-origin H3N8 and avian-origin H3N2 viruses, which are both established lineages in dogs worldwide. Canine influenza virus [...]

AbstractVacuum preloading combined with flocculation has shown great potential for improving the dredged sludge’s dewatering and consolidation. To identify a suitable flocculant combined with vacuum preloading method, this study investigated the effects of various common flocculants on the sludge’s filtration properties and consolidation behaviors. The results indicated that dual-use of polymeric aluminium chloride (PAC) and polyacrylamide (PAM) had the most significant improvement on sludge’s filtration performance, as reflected by capillary suction time. In addition, a single dose of PAM had the most substantial improvement on the sludge’s compressibility. While, lime improved the sludge’s permeability the most. To predict the consolidation settlement of flocculated sludge during vacuum preloading, a method was proposed based on a small homemade vacuum preloading apparatus and the Taylor method. The influence of different flocculants on sludge properties was also analyzed based on their flocculation mechanisms and microstructure. Finally, an appropriate flocculant for the sludge in vacuum preloading projects was suggested in accordance with different project goals. [ABSTRACT FROM AUTHOR]

Understanding the stability of the seabed foundation holds paramount significance in guaranteeing the safety and structural soundness of the breakwater alongside additional offshore structures. This study aimed to investigate the stability of a sandy seabed foundation around a semi-circular breakwater under wave loading in nearshore areas. A coupled numerical model of waves, a semi-circular breakwater, and the seabed was developed based on the OpenFOAM platform. The VARANS equations were used to govern the wave behavior. Meanwhile, the Biot's partially dynamic model was employed to numerically simulate the seabed response considering both consolidation under self-weight and dynamic response under wave loading. The effects of various wave parameters, seabed properties, and the radius of the structure on the dynamic response of the seabed and the depth of liquefaction were investigated. The numerical results indicate that an increase in wave height, period, and permeability coefficient intensifies the dynamic response of the seabed soil. Furthermore, an increase in water depth weakened the soil's dynamic response. There was a negative correlation between the radius of the semi-circular breakwater and the dynamic response. The influence of Poisson's ratio on the dynamic response of the seabed was relatively small. Furthermore, a stronger dynamic pore pressure response was observed at the connection between the semi-circular breakwater and the rubble foundation. [ABSTRACT FROM AUTHOR]