Shape Classification Using a Single Seal-Whisker-Style Sensor Based on the Neural Network Method.

Seals, sea lions, and other aquatic animals rely on their whiskers to identify and track underwater targets, offering valuable inspiration for the development of low-power, portable, and environmentally friendly sensors. Here, we design a single seal-whisker-like cylinder and conduct experiments to measure the forces acting on it with nine different upstream targets. Using sample sets constructed from these force signals, a convolutional neural network (CNN) is trained and tested. The results demonstrate that combining the seal-whisker-style sensor with a CNN enables the identification of objects in the water in most cases, although there may be some confusion for certain targets. Increasing the length of the signal samples can enhance the results but may not eliminate these confusions. Our study reveals that high frequencies (greater than 5 Hz) are irrelevant in our model. Lift signals present more distinct and distinguishable features than drag signals, serving as the primary basis for the model to differentiate between various targets. Fourier analysis indicates that the model's efficacy in recognizing different targets relies heavily on the discrepancies in the spectral features of the lift signals.

Variations in water exchange in the sub-areas of a bay following large-scale land reclamation.

Semi-enclosed bays often have weak water exchange capacities, leading to frequent environmental pollution, particularly localized pollution. This study examines the local effects of changes in local factors on water circulation within Bohai Bay after land reclamation. To address the limitations of previous methods in measuring sub-regional water exchange, we introduce the concept of Local Average Influence Time (LAIT) to qualitatively and quantitatively analyze the impact of land reclamation on water exchange between sub-regions in semi-enclosed bays. Results indicate that land reclamation can enhance the self-purification capacity of sub-regions with significant shoreline changes in Bohai Bay, but this improvement is closely linked to dynamic factors such as wind, tide, and runoff. The degree of water exchange between sub-regions shows significant spatial heterogeneity, with land reclamation influencing the primary direction of water transport. This is largely due to the obstruction caused by newly constructed artificial headlands, making the neighbor area new high-risk zones for pollution. Wind can promote water circulation within the bay, but its effects are spatially heterogeneous and sensitive to shoreline topography changes. River discharge can enhance local water exchange but is weakened by obstruction from artificial headlands. Tide promotes water exchange between the bay mouth and inner bay areas, while their impact on sub-regional water exchange is also spatially heterogeneous and sensitive to changes in shoreline and topography. This study provides a quantitative method for assessing water exchange between regions and offers insights into the impact of land reclamation on water circulation within semi-enclosed bays.