Part-Whole Relational Few-Shot 3D Point Cloud Semantic Segmentation

This paper focuses on the task of few-shot 3D point cloud semantic segmentation.Despite some progress,this task still encounters many issues due to the insufficient samples given,e.g.,incomplete object segmentation and inaccurate semantic discrimination.To tackle these issues,we first leverage part-whole relationships into the task of 3D point cloud semantic segmentation to capture semantic integrity,which is empowered by the dynamic capsule routing with the module of 3D Capsule Networks(CapsNets)in the embedding network.Concretely,the dynamic routing amalgamates geometric information of the 3D point cloud data to construct higher-level feature representations,which capture the relationships between object parts and their wholes.Secondly,we designed a multi-prototype enhancement module to enhance the prototype discriminability.Specifically,the single-prototype enhancement mechanism is expanded to the multi-prototype enhancement version for capturing rich semantics.Besides,the shot-correlation within the category is calculated via the interaction of different samples to enhance the intra-category similarity.Ablation studies prove that the involved part-whole relations and proposed multi-prototype enhancement module help to achieve complete object segmentation and improve semantic discrimination.Moreover,under the integration of these two modules,quantitative and qualitative experiments on two public benchmarks,including S3DIS and ScanNet,indicate the superior performance of the proposed framework on the task of 3D point cloud semantic segmentation,compared to some state-of-the-art methods.

A Cross-Seasonal Linkage between Arctic Sea Ice and Eurasian Summertime Temperature Fluctuations

This study explores the linkage between summertime temperature fluctuations over midlatitude Eurasia and the preceding Arctic sea ice concentration (SIC) by utilizing the squared norm of the temperature anomaly, the essential part of local eddy available potential energy, as a metric to quantify the temperature fluctuations with weather patterns on various timescales. By comparing groups of singular value decomposition (SVD) analysis, we suggest a significant linkage between strong (weak) August 10-to-30-day temperature fluctuations over mid-west Asia and enhanced (decreased) Barents-Kara Sea ice in the previous February. We find that when the February SIC increases in the Barents-Kara Sea, a zonal dipolar pattern of SST anomalies appears in the Atlantic subpolar region and lasts from February into the summer months. Evidence suggests that in such a background state, the atmospheric circulation changes evidently from July to August, so that the August is characterized by an amplified meridional circulation over Eurasia, weakened westerlies, and high- pressure anomalies along the Arctic coast. Moreover, the 10-to-30-day wave becomes more active in the North Atlantic-Barents-Kara Sea-Central Asia regions and manifests a more evident southward propagation from the Barents- Kara Sea into the Ural region, which is responsible for the enhanced 10-to-30-day wave activity and temperature fluctuations in the region.

The impact of concurrent variation of atmospheric meridional heat transport in western Baffen Bay and eastern Greenland on summer Arctic sea ice

Based on the climatological reanalysis data of the European Center for Medium-Range Weather Forecasts and the Arctic sea ice data of the National Snow and Ice Data Center, the relationship between the Arctic sea ice area(SIA)and the interannual variation of atmospheric meridional heat transport(AMHT) was analyzed. The results show that the atmospheric meridional heat transported by transient eddy(TAMHT) dominates the June AMHT in midhigh latitudes of the Northern Hemisphere, while the western Baffin Bay(B) and the eastern Greenland(G) are two gates for TAMHT entering the Arctic. TAMHT in the western Baffin Bay(B-TAMHT) and eastern Greenland(G-TAMHT) has a concurrent variation of reverse phase, which is closely related to the summer Arctic SIA.Possible mechanism is that the three Arctic atmospheric circulation patterns(AD, AO and NAO) in June can cause the concurrent variation of TAMHT in the B and G regions. This concurrent variation helps to maintain AD anomaly in summer through wave action and changes the polar air temperature, thus affecting the summer Arctic SIA. Calling the heat entering the Arctic as warm transport and the heat leaving Arctic as cold transport, then the results are classified into three situations based on B-TAMHT and G-TAMHT: warm B corresponding to cold G(WC), cold B corresponding to warm G(CW), cold B corresponding to cold G(CC), while warm B corresponding to warm G is virtually non-existent. During the WC situation, the SIA in the Pacific Arctic sediments and Kara Sea decreases;during the CW situation, the SIA in the Laptev Sea and Kara Sea decreases;during the CC situation, the SIA in the Kara Sea, Laptev Sea and southern Beaufort Sea increases.

夏季外来气旋对北极太平洋扇区海冰的影响

近40年来,北极太平洋扇区8~10月海冰面积显著减少,其减少速率几乎是大西洋扇区的3倍,且该扇区海冰面积年际变率显著,标准差达6×105km2.基于ECMWF提供的再分析气象数据和NSIDC提供的海冰密集度、海冰运动及气旋资料,分析了外来气旋活动对北极太平洋扇区海冰面积年际变化的影响.研究表明:每年7~9月的外来气旋异常偏多(偏少)时,北极太平洋扇区海冰面积明显减少(增多),二者负相关最显著的区域位于楚科奇海、波弗特海、东西伯利亚海及中央海区.深入分析其作用机制发现:外来气旋活动加强时,受其对地表能量平衡和温度平流等综合影响,北极扇区大部分地区气温都明显上升,从而促进了该扇区海冰消融.同时气旋活动带来的大风会驱动海冰运动,使得边缘海区易形成更多开阔水域,海水显著增暖,加剧边缘海海冰融化.除此之外,气旋大风还会造成东西伯利亚海海冰向东和向南更暖的区域输送,也利于海冰的消融.总体来看,北极太平洋扇区海冰消融主要与气旋的热力作用有关,其动力作用主要影响边缘海域.

N-methylation of quinolines with CO2 and H2 catalyzed by Ru-triphos complexes

N-methyl-tetrahydroquinolines(MTHQs) are a kind of very useful chemicals, which can be obtained from N-methylation of amines.However, the methylation of quinolines which is a kind of highly unsaturated nitrogen-containing heterocyclic aromatic compounds has not been reported. In this work, we report the first work for the synthesis of MTHQs by methylation of quinolines using CO_2 and H_2. It was found that Ru(acac)_3-triphos [triphos: 1,1,1-tris(diphenylphosphinomethyl)ethanl] complex was very active and selective for the N-methylation reaction of quinolines, and the yield of the desired product could reach 99%.

Multiple plasmon couplings in 3D hybrid Au-nanoparticles-decorated Ag nanocone arrays boosting highly sensitive surface enhanced Raman scattering

Plasmon coupling is an essential strategy to realize strong local electromagnetic(EM)field which is crucial for high-performance plasmonic devices.In this work,multiple plasmon couplings are demonstrated in three-dimensional(3D)hybrid plasmonic systems composed of polydimethylsiloxane-supported ordered silver nanocone(AgNC)arrays decorated with high-density gold nanoparticles(AuNPs)which are fabricated by a template-assisted physical vapor deposition process.Strong interparticle coupling,particle-film coupling,inter-cone coupling,and particle-cone coupling are revealed by numerical simulations in such composite nanostructures,which produce intense and high-density EM hot spots,boosting highly sensitive and reproducible surface enhanced Raman scattering(SERS)detection with an enhancement factor of-1.74×10^(8).Furthermore,a linear correlation between logarithmic Raman intensity and logarithmic concentration of probe molecules is observed in a large concentration range.These results offer new ideas to develop novel plasmonic devices,and provide alternative strategy to realize flexible and high-performance SERS sensors for trace molecule detection and quantitative analysis.

Synthesis of phosphanaphthalenes and nido-carborane fused six-membered phosphacycles

A simple method to synthesize luminescent λ^(5)-phosphanaphthalenes and zwitterionic nido-carborane fused six-membered phosphacycles was developed from the reaction of ortho-phosphinobenzoaldehydes or ortho-phosphinocarboranylaldehydes with an electron-deficient alkyne,respectively.Similar results were obtained with the imino analogues.