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Serious computational instability problems are usually encountered in solving the sedimentation-consolidation model based on an interaction coefficient (SCMIC). In this study, the computational instability behavior of SCMIC is investigated with given upwind finite difference scheme. Results show that significant numerical errors occur when low grid density is used. By analyzing the variations of governing equation coefficients with time, it is found that the computational instability is due to the highly nonlinear variation of d σ ′ d e with e ( σ ′ is effective stress and e is void ratio), which causes significant errors in calculating the average value of d σ ′ d e. By eliminating the effect of the high nonlinearity of d σ ′ d e , the computational instability of SCMIC can be completely resolved. Such a resolution method for the computational instability overcomes the restriction of grid density, which can facilitate the simulation of simultaneous sedimentation and consolidation in the geotechnical engineering field. [ABSTRACT FROM AUTHOR]

Purpose: This research presents experimental investigation into the performance improvement of dredged sediment (DS) stabilization with ternary alkali-activated materials (AAMs) based on fly ash (FA), ground granulated blast-furnace slag (GGBS), and desulfurization gypsum (DG) for use as embankment fill materials. Methods: The performance of stabilized DS was assessed through a series of pH, electrical conductivity (EC), and unconfined compressive strength (UCS) tests. Microstructure characterization was also conducted to reveal the performance improvement mechanism of stabilized DS. Results: The pH value of the stabilized DS exhibited a significant increase, reaching its peak at a DG content of 8%. This increase was attributed to the consumption of free water and the priority reaction of C-(A)-S–H. Subsequently, the pH value gradually decreased, primarily due to the consumption of OH− through Ca(OH)2 precipitation. Concurrently, the EC value steadily increased due to the rising Ca2+ concentration. Additionally, the UCS of the stabilized DS exhibited a noteworthy increase at a DG content of 8% and then showed a tendency to increase or decrease slightly with varying DG content, in line with the changes in pH value. Conclusions: The performance improvement of the stabilized DS was attributable to the cementation provided gels (i.e., geopolymer gel and C-(A)-S–H gel), along with the pore-filling of ettringite (AFt) in the alkaline environment. Conversely, the performance of stabilized DS deteriorated due to the presence of microcracks resulting from excessive AFt expansion. [ABSTRACT FROM AUTHOR]

Massive landfilling of red mud (alumina residue, RM) has posed a great challenge to the sustainable development of the alumina industry. To consume such vast industrial wastes, it is of great benefits to promote reuse of RM in land reclamation to replace partial traditional cementitious materials. This study investigates the potential use of the RM in stabilizing marine dredged clay (MDC) with a low dosage of cement, where sodium silicate is used as an alkali-activator. A series of laboratory tests are performed to characterize positive role of alkali-activated RM in improving mechanical and microstructural properties of cement-treated MDC. The variation of strength, permeability and micro characteristics are examined with different RM contents, sodium silicate contents and curing time. The results indicate an optimal content of sodium silicate regardless of curing time, which grows from 10% to 20% when RM content increases from 5% to 15%. Both hydration and polymerization reactions occur in the mixture of MDC, cement and alkali-activated RM, generating products including hydration gels (C–S–H and N–A–S–H) and geopolymer (analcime, faujasite and unnamed zelites). With optimal content of alkali, the stacked structure combining quadrate crystal clusters and gels can be observed, which contributes to significant strength improvement of stabilized MDC. [ABSTRACT FROM AUTHOR]

Cement-based treatment is a well-established technology for converting unwanted marine dredged clay (MDC) to qualified filling materials. However, a basic understanding of the strength development of cement-treated MDC is still lacking. In this study, we attempt to characterize the strength variation of cement-treated MDC under a wide range of water-to-cement ratios (w/c). The dominant influencing factors such as initial water content, cement content, curing time and pore salinity are examined through a series of laboratory tests. The results indicate that the strength of cement-treated MDC decreases exponentially with the initial water content. The strength approaches zero when the initial water content increases to 3.5–4.0 times the liquid limit, even with a high content of cement. The effect of pore salinity depends significantly on the cement content and curing time. Owing to the wide range of w/c, the extensively used Abrams' law fails to characterize the strength variation of cement-treated MDC precisely. To this end, a new strength prediction model is proposed based on the concept of minimum cement content. The volume ratio is found to be inferior to the mass ratio in defining the minimum cement content, which remains approximately constant even for a wide range of w/c. [ABSTRACT FROM AUTHOR]

This event-related potential (ERP) study examined the effect of contextual arousal on emotional word integration during discourse comprehension. We used two-sentence discourses as experimental materials. The first sentence served as an emotional context and described a high-arousal positive event, a low-arousal positive event, a high-arousal negative event, or a low-arousal negative event. The second sentence contained one negative word as the critical word, which was identical among different conditions. Thus, four conditions were included in the present study: high-arousal inconsistent, low-arousal inconsistent, high-arousal consistent, and low-arousal consistent. The ERP results showed that inconsistent emotional words elicited larger P200 and LPC than consistent words in the high-arousal context. However, only a P200 effect was observed for inconsistent emotional words in the low-arousal context. Our results indicate that a high-arousal context could lead to more elaborated emotional evaluation in the later stage of emotional word integration and suggest an important role of contextual arousal on the processing of emotional words during discourse processing. [ABSTRACT FROM AUTHOR]

Cement-based solidification technology is an ideal solution to convert undesirable marine dredged clay (MDC) to qualified filling materials. Industrial by-products (e.g., fly ash) are commonly added as partial replacement of cement, aiming to reduce carbon emissions and relieve severe stockpiles of industrial wastes. Red mud (RM) and phosphogypsum (PG) are increasingly generated and dumped in China, but have an extremely low utilization rate among various by-products. Potential use of the combined RM with PG in improving cement-treated MDC is experimentally investigated in this paper. A series of laboratory tests, including unconfined compressive strength (UCS) tests, hydraulic conductivity tests, microscopic tests, were carried out. The influence of RM/PG ratio, initial water content and cement content on mechanical and microscopic properties was examined, respectively. The results indicate that the role of 5% RM combined with 5% PG (by dry weight of soils) in improving strength approaches that of 5% additional cement. As cement content reaches 20%, the hydraulic conductivity of stabilized MDC decreases below 1 × 10–8 cm/s with optimum content of wastes. The stabilized MDC with combined RM and PG has a denser microstructure due to mutual promotion between RM and PG. The sulfate ions provided by PG help to break bonds of Si–O and Al-O in the RM and MDC with an alkaline environment, generating more C-S–H, C-A-H and C-A-S–H. The produced C-AH contributes to the formation of ettringite with sulfate ions released from the PG in turn. The combined RM with PG shows promising application in cement-based solidification of MDC. [ABSTRACT FROM AUTHOR]

In this paper, a 210–280 GHz balanced broadband tripler based on a planar Schottky diode is designed and manufactured. Compared with the traditional tripler, the terahertz tripler adopts the modular design method of device and circuit combination and carries on the electromagnetic modeling of the diode according to the physical parameters of the diode. Combined with SPICE model simulation, it is conducive to accurately simulate the tripler. It has the characteristics of simple assembly, low loss, and stability. The reverse parallel diode pair is used as the core of the tripler to generate multiple harmonics, and the circuit is designed to obtain the required third harmonics. Under the condition that the input power is 5 dBm, the output power of the tripler is about −4.3 to −7 dBm in the frequency band of 210–280 GHz, and the bandwidth is about 28%. At 252 GHz, the output power is −4.3 dBm, and the conversion efficiency is about 11.7%, which is in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

Soft marine deposits are widely distributed in the coastal region of China. The marine soft clays have high water content and high sensitivity, which shows high compressibility and low strength. The installation of precast piles for wind turbines over soft marine clay will generate high excess pore water pressure (EPWP) with very low dissipation rate, resulting in low bearing capacity and large postconstruction settlement, which will affect long-term stability. This study investigated the generation and dissipation of the EPWP correlated with the change in soil structure during the installation of pile foundations in a project of 100 MW wind-power generation in Lianyungang, Jiangsu, China. The results show that the marine soft clay soils feature strong natural structures based on the intrinsic compression concept. The EPWP decreases with increasing distance from the pile, whose influence reaches a distance of 6 m (about 10 times the pile side length). The structural strength of natural sedimentary clay has a remarkable impact on the generated EPWP. The dissipation rate of the EPWP is very slow in mucky clay with more than half the residual value after 30 days, which is mainly attributed to the sharp decline of consolidation coefficient induced by the disturbance of natural clay soils from pile driving. Moreover, hydraulic fracturing can well explain the dissipation characteristics of the EPWP in clay. This phenomenon is actually an ongoing process especially in marine soft clay soils with a strong cementation effect. [ABSTRACT FROM AUTHOR]