Phase-modulated continuous-wave (PMCW) radars offer better multiple antenna support and flexible waveform design. These radars, however, suffer from the high computational complexity of correlation processing used to obtain the range of targets, particularly due to the use of long code sequences. To address this, we exploit signal sparsity and propose an adaptive sliding block-based fast Fourier transform (FFT) correlator that selectively processes only the relevant range bins and dynamically aligns processing blocks using a time-shift parameter. This sliding mechanism minimizes boundary effects and reduces the number of blocks required for processing. The framework also incorporates external sensor data for context-aware range-bin selection and includes an analytical formulation for optimal block size selection. Simulations demonstrate that the proposed method preserves the signal-to-noise ratio (SNR) and target peaks while significantly reducing processing time. The effectiveness of the proposed method is demonstrated through numerical simulations.

The use of digital sequences in automotive radars provides better support for multiple antennas in imaging radar applications. However, a challenge in such digital radars is the higher complexity in the receiver processing chain, starting from the bank of correlators used to estimate the range of targets. State-of-the-art correlators are implemented using using fast Fourier transforms (FFTs), which have log linear complexity in the FFT length used in correlating the digital sequence with the received sequence. This Results in high complexity due to the large sequence lengths needed to achieve high sensing range and fine velocity resolution. We propose an adaptive block FFT-based correlator processing method that exploits sparsity in the range domain. In comparison to conventional FFT-based correlator processing, the proposed method provides a significant reduction in complexity.

Deltas are widely threatened by sediment starvation and climate change. Erosion potential is an important indicator of delta vulnerability. Here, we investigate the erosion potential of the Yangtze Delta. We found that over the past half century the Yangtze's sediment discharge has decreased by 80% due to the construction of >50,000 dams and soil conservation, whereas the wind speed and wave height in the delta region have increased by 5-7%, and the sea level has risen at a rate of 3 mm/yr. According to hydrodynamic measurements and analyses of seabed sediments, the period when bed shear stress due to combined current-wave action under normal weather conditions exceeds the critical bed shear stress for erosion (τ_cr) accounts for 63% of the total observed period on average and can reach 100% during peak storms. This explains why net erosion has occurred in some areas of the subaqueous delta. We also found that the increase with depth of τ_cr is very gradual in the uppermost several metres of the depositional sequence. We therefore expect that the Yangtze subaqueous delta will experience continuous erosion under sediment starvation and climate change in the next decades of this century or even a few centuries.