Electromagnetic Scattering Model for Far Wakes of Ship with Wind Waves on Sea Surface

A comprehensive electromagnetic scattering model for ship wakes on the sea surface is proposed to study the synthetic aperture radar (SAR) imagery for ship wakes. Our model considers a coupling of various wave systems, including Kelvin wake, turbulent wake, and the ocean ambient waves induced by the local wind. The fluid–structure coupling between the ship and the water surface is considered using the Reynolds–averaged Navier–Stokes (RANS) equation, and the wave–current effect between the ship wake and wind waves is considered using the wave modulation model. The scattering model can better describe the interaction of the ship wakes on sea surface and illustrates well the features of the ship wakes with local wind waves in SAR images.

Involvement of bilateral insula in brand extension evaluation: an fMRI study

The present study aims to investigate functional involvement of brain areas in consumers’ evaluation of brand extension that refers to the use of well-established brand for launching new offerings. During functional magnetic resonance imaging (fMRI) scanning, participants viewed a beverage brand name followed by an extension goods name selected from the beverage or household appliance categories. They responded acceptability to given brand extension. Both acceptability responses and reaction time revealed a noticeable pattern that participants responded to acceptable stimuli more carefully. General linear model (GLM) analyses revealed the involvement of insular activity in brand extension evaluation. Especially, insular activity was lateralized according to valence. Furthermore, its activity could explain behavioral response in parametric modulation model. According to these results, we speculate that insula activity is relevant to emotional processing. Finally, we divided neural activities during brand extension into separated clusters using a hierarchical clustering-based connectivity analysis. Excluding two of them related to sensorimotor functions for behavioral responses, the remaining cluster, including bilateral insula, was likely to reflect brand extension assessment. Hence, we speculate that consumers’ brand extension evaluation may involve emotional processes, shown as insular activity.

Can Humans Become More Random?

The human ability for random-sequence generation (RSG) is limited but improves in a competitive game environment with feedback. However, it remains unclear whether RSG during games can improve when explicitly informing people that they must be as random as possible to win the game nor is it known whether any such improvement transfers to outside the game environment. To investigate this, we designed a pre/post intervention paradigm around a rock-paper-scissors game followed by a questionnaire. During the game we manipulated participants’ level of awareness of the computer’s strategy; they were either (a) not informed of the computer’s algorithm or (b) explicitly informed that the computer used patterns in their choice history to beat them, so they must be maximally random to win. Using a novel comparison metric, our results demonstrate that human RSG can reach levels statistically indistinguishable from computer pseudo-random generators in a competitive-game setting. However, our results also suggest that human RSG cannot be further improved by explicitly informing participants that they need to be random to win. In addition, the higher RSG in the game setting does not transfer outside the game environment. Furthermore, we found that the underrepresentation of long repetitions of short patterns explains about a third of the variability in human RSG and discuss what might make up the remaining two thirds of RSG variability. Finally, we discuss our results in the context of the “Network-Modulation Model” and we ponder their potential relation to findings in the neuroscience of volition.

Full Range Capacitor Voltage Balance PWM Strategy for Diode-Clamped Multilevel Inverter

This paper briefly reviews virtual space vector pulse width modulation (VSVPWM) for the diode-clamped multilevel inverter (DCMLI). Based on the universal modulation model of the DCMLI with N-level, a modulation strategy named as full range capacitor voltage balance PWM (FRCVBPWM) is proposed, which has similar capacitor voltage balance characteristics as VSVPWM. The characteristic of FRCVBPWM is that there are respectively zero, N − 1 and N − 2 switching actions for the three phases of the DCMLI. Therefore, the total switching actions are greatly decreased compared with VSVPWM. The switching loss comparison between FRCVBPWM and VSVPWM is conducted by comprehensive simulations. Finally, the feasibility and superiority of FRCVBPWM over VSVPWM is verified by experiments.

An Improved Descalloping Method Combined With Imaging Parameters for GaoFen-3 ScanSAR

Due to the specific working mechanism of alternately transmitting and receiving signals between multiple adjacent swaths, scanning synthetic aperture radar (ScanSAR) will cause periodical wavelike modulation of the intensity image along azimuth direction, which is known as scalloping. Conventional descalloping methods are achieved by proper azimuth antenna pattern (AAP) correction and multi-looking techniques but are limited by the accuracy of Doppler centroid estimating and the thermal noise. Another type of method extracts and suppresses the scalloping texture on the image, but the scanning parameters of ScanSAR are insufficiently considered. The period of scalloping on the image is related to the period of switching between subswathes. While the harmonics can be calculated by the period of a periodic signal, an improved frequency filtering method combined with imaging parameters is proposed. The scalloping modulation model of ScanSAR combined with imaging parameters is constructed, and the harmonics of scalloping texture are accurately calculated and filtered. For the low signal to noise ratio (SNR) image, the antenna pattern is modified according to SNR to avoid scalloping caused by noise. For non-uniform scenes, scalloping suppression is achieved by using the scalloping features acquired by uniform scenes. To separate the non-uniform scenes from uniform scenes, we still use the characteristics of harmonics caused by scalloping. Our descalloping method achieves accurate suppression of scalloping without sea-land segmentation and ship mask and the residual scalloping is reduced from 1.0 to 0.3–0.5 dB. The residual scalloping and statistical characteristics of the image are analyzed to demonstrate the effectiveness of the proposed method.