In this paper, a numerical model for nonlinear wave propagation in currents is formulated by a set of enhanced fully nonlinear Boussinesq equations with ambient currents. This model is verified by comparison with the ...In this paper, a numerical model for nonlinear wave propagation in currents is formulated by a set of enhanced fully nonlinear Boussinesq equations with ambient currents. This model is verified by comparison with the published results. Then the influence of currents on nonlinear focusing waves is studied by use of the numerical model. It is found that the effect of currents on the surface elevations at the fecal location is negligible. Following currents can augment the maximum crest of focusing wave while decrease the focusing time, and vice versa for opposing currents. Furthermore, both opposing and following currents can shift the focal location forward relative to that in quiescent water.展开更多
An offshore shoal or bar refracts ocean surface waves and causes wave focusing/defocusing on the adjacent beach. Wave focal patterns characterized by alongshore variations in wave height, wave angle, and breaking loca...An offshore shoal or bar refracts ocean surface waves and causes wave focusing/defocusing on the adjacent beach. Wave focal patterns characterized by alongshore variations in wave height, wave angle, and breaking location induce alongshore non-uniformities of wave setup and nearshore circulation, e.g., rip currents and alongshore currents, in the surfzone. A simplified analytic model for nearshore circulation generated by focused/defocused waves on a planar beach is developed and theoretical solutions are obtained using transport stream function and perturbations in alongshore distributions of wave height and wave angle at the breaker line. The analytic model suggests that alongshore currents are strongly affected by a pair of counter-rotating vortices generated shoreward of the wave focal zone. The vortices are persistent, and their strengths depend on the amplitudes of alongshore variations in wave height and wave angle. The alongshore gradient in wave height tends to intensify the vortices while the convergence of wave angle tends to weaken the vortices. Divergent flows associated with the vortices in the surfzone are intense, strengthening alongshore currents in the downstream of the wave focal zone and weakening alongshore currents or causing flows reversal in the upstream. Alongshore currents are modulated by rip currents associated with the wave focusing/defocusing patterns.展开更多
Ning et al. （2015） developed a 2D fully nonlinear potential model to investigate the interaction between focused waves and uniform currents. The effects of uniform current on focusing wave crest, focal time and foca...Ning et al. （2015） developed a 2D fully nonlinear potential model to investigate the interaction between focused waves and uniform currents. The effects of uniform current on focusing wave crest, focal time and focal position were given. As its extension, harmonic energy transfer for focused waves in uniform current is studied using the proposed model by Ning et al. （2015） and Fast Fourier Transformation （FFT） technique in this study. It shows that the strong opposing currents, inducing partial wave blocking and reducing the extreme wave crest, make the nonlinear energy transfer non-reversible in the focusing and defocusing processes. The numerical results also provide an explanation to address the shifts of focal points in consideration of the combination effects of wave nonlinearity and current.展开更多
帕金森病(Parkinson's disease,PD)是最常见的神经退行性疾病之一,口服药物是其主要干预方式。近年来,无创神经调控技术在该治疗领域进展迅速,通过与药物治疗协作可显著增强效果并减少不良反应。这类技术通过靶向调控特定神经环路,...帕金森病(Parkinson's disease,PD)是最常见的神经退行性疾病之一,口服药物是其主要干预方式。近年来,无创神经调控技术在该治疗领域进展迅速,通过与药物治疗协作可显著增强效果并减少不良反应。这类技术通过靶向调控特定神经环路,实现精准治疗。本文系统综述了经颅磁刺激(transcranial magnetic stimulation,TMS)、经颅直流电刺激(transcranial direct current stimulation,tDCS)、经颅聚焦超声(transcranial focused ultrasound,tFUS)、经颅光生物调节(transcranial photobiomodulation,tPBM)等物理调控技术在PD康复治疗中的应用进展。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.50679010 and 50921001)the Program for New Century Excellent Talents in Universities of China(Grant No.NCET-05-0282)
文摘In this paper, a numerical model for nonlinear wave propagation in currents is formulated by a set of enhanced fully nonlinear Boussinesq equations with ambient currents. This model is verified by comparison with the published results. Then the influence of currents on nonlinear focusing waves is studied by use of the numerical model. It is found that the effect of currents on the surface elevations at the fecal location is negligible. Following currents can augment the maximum crest of focusing wave while decrease the focusing time, and vice versa for opposing currents. Furthermore, both opposing and following currents can shift the focal location forward relative to that in quiescent water.
基金financially supported by the Tianjin Municipal Science and Technology Commission(Grant No.19JCYBJC22000)
文摘An offshore shoal or bar refracts ocean surface waves and causes wave focusing/defocusing on the adjacent beach. Wave focal patterns characterized by alongshore variations in wave height, wave angle, and breaking location induce alongshore non-uniformities of wave setup and nearshore circulation, e.g., rip currents and alongshore currents, in the surfzone. A simplified analytic model for nearshore circulation generated by focused/defocused waves on a planar beach is developed and theoretical solutions are obtained using transport stream function and perturbations in alongshore distributions of wave height and wave angle at the breaker line. The analytic model suggests that alongshore currents are strongly affected by a pair of counter-rotating vortices generated shoreward of the wave focal zone. The vortices are persistent, and their strengths depend on the amplitudes of alongshore variations in wave height and wave angle. The alongshore gradient in wave height tends to intensify the vortices while the convergence of wave angle tends to weaken the vortices. Divergent flows associated with the vortices in the surfzone are intense, strengthening alongshore currents in the downstream of the wave focal zone and weakening alongshore currents or causing flows reversal in the upstream. Alongshore currents are modulated by rip currents associated with the wave focusing/defocusing patterns.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51679036 and 51490672)the Royal Academy of Engineering under the UK-China Industry Academia Partnership Programme(Grant No.UK-CIAPP\73)the Program for New Century Excellent Talents in University(Grant No.NCET-13-0076)
文摘Ning et al. （2015） developed a 2D fully nonlinear potential model to investigate the interaction between focused waves and uniform currents. The effects of uniform current on focusing wave crest, focal time and focal position were given. As its extension, harmonic energy transfer for focused waves in uniform current is studied using the proposed model by Ning et al. （2015） and Fast Fourier Transformation （FFT） technique in this study. It shows that the strong opposing currents, inducing partial wave blocking and reducing the extreme wave crest, make the nonlinear energy transfer non-reversible in the focusing and defocusing processes. The numerical results also provide an explanation to address the shifts of focal points in consideration of the combination effects of wave nonlinearity and current.
文摘帕金森病(Parkinson's disease,PD)是最常见的神经退行性疾病之一,口服药物是其主要干预方式。近年来,无创神经调控技术在该治疗领域进展迅速,通过与药物治疗协作可显著增强效果并减少不良反应。这类技术通过靶向调控特定神经环路,实现精准治疗。本文系统综述了经颅磁刺激(transcranial magnetic stimulation,TMS)、经颅直流电刺激(transcranial direct current stimulation,tDCS)、经颅聚焦超声(transcranial focused ultrasound,tFUS)、经颅光生物调节(transcranial photobiomodulation,tPBM)等物理调控技术在PD康复治疗中的应用进展。
