Convective Storm VIL and Lightning Nowcasting Using Satellite and Weather Radar Measurements Based on Multi-Task Learning Models

Convective storms and lightning are among the most important weather phenomena that are challenging to forecast.In this study,a novel multi-task learning(MTL)encoder-decoder U-net neural network was developed to forecast convective storms and lightning with lead times for up to 90 min,using GOES-16 geostationary satellite infrared brightness temperatures(IRBTs),lightning flashes from Geostationary Lightning Mapper(GLM),and vertically integrated liquid(VIL)from Next Generation Weather Radar(NEXRAD).To cope with the heavily skewed distribution of lightning data,a spatiotemporal exponent-weighted loss function and log-transformed lightning normalization approach were developed.The effects of MTL,single-task learning(STL),and IRBTs as auxiliary input features on convection and lightning nowcasting were investigated.The results showed that normalizing the heavily skew-distributed lightning data along with a log-transformation dramatically outperforms the min-max normalization method for nowcasting an intense lightning event.The MTL model significantly outperformed the STL model for both lightning nowcasting and VIL nowcasting,particularly for intense lightning events.The MTL also helped delay the lightning forecast performance decay with the lead times.Furthermore,incorporating satellite IRBTs as auxiliary input features substantially improved lightning nowcasting,but produced little difference in VIL forecasting.Finally,the MTL model performed better for forecasting both lightning and the VIL of organized convective storms than for isolated cells.

Inverse Optimal Control for Speed-varying Path Following of Marine Vessels with Actuator Dynamics

A controller which is locally optimal near the origin and globally inverse optimal for the nonlinear system is proposed for path following of over actuated marine crafts with actuator dynamics. The motivation is the existence of undesired signals sent to the actuators, which can result in bad behavior in path following. To attenuate the oscillation of the control signal and obtain smooth thrust outputs, the actuator dynamics are added into the ship maneuvering model. Instead of modifying the Line-of-Sight (LOS) guidance law, this proposed controller can easily adjust the vessel speed to minimize the large cross-track error caused by the high vessel speed when it is turning. Numerical simulations demonstrate the validity of this proposed controller.

Comparison of Clinical Value between Right Distal Radial Artery Access and Right Radial Artery Access in Patients Undergoing Coronary Angiography or Percutaneous Coronary Intervention

Objective:To compare the feasibility and safety between right distal radial artery access and right radial artery access in patients undergoing coronary angiography(CAG)or percutaneous coronary intervention(PCI).Methods:On the basis of arterial access,113 patients who underwent CAG or PCI in Kunshan Hospital of Traditional Chinese Medicine between January and October 2018 were divided into two groups:a right distal radial artery group(52 patients)and a right radial artery group(61 patients).We collected general information,the number of puncture attempts,access times,postoperative compression time,and complications.Results:The general characteristics,rate of successful radial artery puncture,and rate of successful catheter placement in the two groups were not different.The right radial artery group had fewer puncture attempts(1.26±0.44 times vs.2.19±0.53 times,P=0.001)and a shorter access time(3.23±0.86 min vs.4.77±1.49 min,P=0.001)than the right distal radial artery group.However,the postoperative compression time in the right distal radial artery group was shorter(3.44±0.9 h vs.7.16±1.21 h,P=0.001).Two cases of bleeding,four cases of hematoma,and one case of artery occlusion in the right radial artery group and one case of hematoma in the right distal artery group occurred before discharge.The rate of total complications in the right distal radial artery group was lower than in the right radial artery group(1.93%vs.11.48%,P=0.048).Conclusion:CAG or PCI through the right distal radial artery is feasible and safe.

陆地生态系统中马陆的生态功能

马陆是陆地生态系统中物种多样性极高的大型土壤无脊椎动物类群。作为营腐生动物,马陆在陆地生态系统中具有不可替代的重要功能。通过大量取食及随后的肠道过程,马陆在很大程度上决定着陆地生态系统凋落物的破碎、转化和分解过程,从而驱动碳和关键养分元素的循环周转。然而,目前对马陆生态功能的研究还非常有限,远远落后于其他土壤动物类群(如蚯蚓等)。本文初步总结了马陆的生态功能:(1)通过破碎、取食凋落物来加速凋落物的分解。马陆偏好取食半分解的凋落物,其同化效率受到凋落物来源、温度和凋落物中微生物含量的影响。(2)主要通过取食和排泄等活动影响养分循环。但对于马陆如何影响土壤碳循环,存在两种不同的观点:一是马陆粪球的分解速率比凋落物更快,加速了碳的循环;二是马陆粪球更难分解,有助于碳的固存和稳定。马陆破碎凋落物后,凋落物释放氮素进入土壤。此外,马陆的活动也影响土壤磷的循环,提高土壤中有效磷的含量。(3)调控微生物特性,与蚯蚓也有互作关系。通过以上三个方面的总结,展望了未来马陆的主要研究方向,以期引起更多思考和研究。