Does sleep-dependent consolidation favour weak memories?

Sleep stabilizes newly acquired memories, a process referred to as memory consolidation. According to recent studies, sleep-dependent consolidation processes might be deployed to different extents for different types of memories. In particular, weaker memories might benefit greater from post-learning sleep than stronger memories. However, under standard testing conditions, sleep-dependent consolidation effects for stronger memories might be obscured by ceiling effects. To test this possibility, we devised a new memory paradigm (Memory Arena) in which participants learned temporospatial arrangements of objects. Prior to a delay period spent either awake or asleep, training thresholds were controlled to yield relatively weak or relatively strong memories. After the delay period, retrieval difficulty was controlled via the presence or absence of a retroactive interference task. Under standard testing conditions (no interference), a sleep-dependent consolidation effect was indeed observed for weaker memories only. Critically though, with increased retrieval demands, sleep-dependent consolidation effects were seen for both weaker and stronger memories. These results suggest that all memories are consolidated during sleep, but that memories of different strengths warrant different testing conditions to unveil their benefit from post-learning sleep.

Analysis of the Effectiveness of the Step Vacuum Preloading Method: A Case Study on High Clay Content Dredger Fill in Tianjin, China

As a solution to avoid the blockage of the drainage pipe by traditional vacuum preloading, step vacuum preloading (SVP) has been progressively studied. However, the effectiveness of this technique has yet to be systematically analyzed. In this study, an indoor model test was conducted in which vacuum pressure was applied in five stages (10, 20, 40, 60, and 80 kPa) to dredger soil with high clay content at a reclamation site in Binhai New Area, Tianjin, China. The extent of the consolidation effect of the soil was determined, and the effectiveness of the step vacuum preloading method to address drainage pipe blockage was evaluated. The results indicate that soil settlement increases at each stage of vacuum pressure treatment and the degree of vertical consolidation at each stage exceeds 90%. At the end of the treatment stage with vacuum pressure of 80 kPa, the weakly bound water was discharged. Dissipation of pore water pressure occurred in all stages. On the basis of these results, it is shown that SVP can efficiently reinforce dredger fill. Moreover, after SVP, the grain size of the soil and void ratio are still uniformly distributed. Regardless of their location from the drainage pipe, soil exhibits permeability coefficients within the same order of magnitude. The consolidation effect of soil in each stage and the increased drainage rate in the initial stage of vacuum preloading with 80 kPa indicate that the test in the current study can decrease the horizontal displacement of fine particles and can avoid drainage pipe blockage.

Finite element analysis of soft foundation treatment by thermal drainage consolidation of group well

Thermal drainage consolidation method is a new technology of soft foundation treatment, which involves the coupling of thermo-hydro-mechanical field, and the action mechanism is complex. In this paper, taking the model test of thermal drainage consolidation as the prototype, the finite element model of thermal drainage consolidation is established by using Abaqus software, then, the numerical results are obtained and are compared with the results of model test, and the reliability of the numerical model is verified. The results show that when the applied load is constant, the higher the temperature is, the faster the consolidation speed of soil is, but with the increase of temperature, the consolidation effect of the same temperature difference will gradually weaken. In addition, the thermal drainage consolidation method can achieve the best treatment effect when the temperature of the soil reaches 60 ℃.

Numerical simulation and experimental study of the bursting performance of triaxial woven fabric and its reinforced rubber composites

In this paper, the bursting performance of triaxial woven fabric and its reinforced rubber composites are studied by the finite element method and the experimental approach, and compared with plain woven fabric and its reinforced rubber composites. The bursting morphologies and load–displacement curves of the specimens during the bursting process are obtained. The results indicate that the rubber matrix has a protective and consolidation effect on the inner fabric, significantly improving the bursting strength of the fabric. Triaxial woven fabric shows a steeper load–displacement slope, higher maximum bursting load, and smaller initial damage displacement than plain woven fabric. The bursting morphologies of the specimens indicate that the structure of triaxial woven fabric is more stable and exhibits good expansion resistance to bursting damage. The bursting process of triaxial woven fabric can be divided into four stages: yarn straightening, yarn slippage, yarn breakage, and breakage extension.

Consolidation Effect of Prefabricated Vertical Drains with Different Lengths for Soft Subsoil under Vacuum Preloading

The application of vacuum preloading to prefabricated vertical drains (PVDs) with different lengths is widely used in practical engineering to investigate their consolidation at the same depths of even and multilayer subsoils from the seabed. In a laboratory, model experiment was conducted using even subsoil and embedded PVDs with lengths of 0.6 and 1.2 m. The obtained results showed that in the even subsoil, the 1.2 m PVDs maintained a higher vacuum pressure in the shallow layer and demonstrated better consolidation behavior as compared to those of the 0.6 m PVDs. In the upper subsoil layer, the average vane shear strengths of these two systems increased to 18.2 and 22.6 kPa, respectively. The degree of consolidation of the upper subsoil layers in the two model experiments calculated from the pore water pressures under boundary drainage conditions were 51% and 68%, respectively. For practical verification purposes, similar experiments were conducted for multilayer subsoil by inserting PVDs with lengths of 6 and 15 m into different test sites. As a result, the vane shear strengths of the upper 6 m subsoil layers increased to 26.3 and 33 kPa, while the degree of consolidation were 72.1% and 80.9%, respectively, although some irregularities were observed at different depths.