A Note on Sectional Curvatures of Hermitian Manifolds

First, we derive expression of the Chern sectional curvature of a Hermitian manifold in local complex coordinates. As an application, we find that a Hermitian metric is K\"ahler if the Riemann sectional curvature and the Chern sectional curvature coincide. Second, we prove that the sectional curvature restricted to orthogonal 2-planes of a G-K\"ahler-like manifold with non-negative (resp. non-positive) sectional curvature can take its maximum (resp. minimum) at a holomorphic plane section. And we also prove that the holomorphic bisectional curvature of a K\"ahler-like manifold with non-negative (resp. non-positive) Chern sectional curvature can take its maximum (resp. minimum) at the holomorphic sectional curvature

Towards Balanced Alignment: Modal-Enhanced Semantic Modeling for Video Moment Retrieval

Video Moment Retrieval (VMR) aims to retrieve temporal segments in untrimmed videos corresponding to a given language query by constructing cross-modal alignment strategies. However, these existing strategies are often sub-optimal since they ignore the modality imbalance problem, \textit{i.e.}, the semantic richness inherent in videos far exceeds that of a given limited-length sentence. Therefore, in pursuit of better alignment, a natural idea is enhancing the video modality to filter out query-irrelevant semantics, and enhancing the text modality to capture more segment-relevant knowledge. In this paper, we introduce Modal-Enhanced Semantic Modeling (MESM), a novel framework for more balanced alignment through enhancing features at two levels. First, we enhance the video modality at the frame-word level through word reconstruction. This strategy emphasizes the portions associated with query words in frame-level features while suppressing irrelevant parts. Therefore, the enhanced video contains less redundant semantics and is more balanced with the textual modality. Second, we enhance the textual modality at the segment-sentence level by learning complementary knowledge from context sentences and ground-truth segments. With the knowledge added to the query, the textual modality thus maintains more meaningful semantics and is more balanced with the video modality. By implementing two levels of MESM, the semantic information from both modalities is more balanced to align, thereby bridging the modality gap. Experiments on three widely used benchmarks, including the out-of-distribution settings, show that the proposed framework achieves a new start-of-the-art performance with notable generalization ability (e.g., 4.42% and 7.69% average gains of [email protected] on Charades-STA and Charades-CG). The code will be available at https://github.com/lntzm/MESM.Comment: Accepted to AAAI 202

MomentDiff: Generative Video Moment Retrieval from Random to Real

Video moment retrieval pursues an efficient and generalized solution to identify the specific temporal segments within an untrimmed video that correspond to a given language description. To achieve this goal, we provide a generative diffusion-based framework called MomentDiff, which simulates a typical human retrieval process from random browsing to gradual localization. Specifically, we first diffuse the real span to random noise, and learn to denoise the random noise to the original span with the guidance of similarity between text and video. This allows the model to learn a mapping from arbitrary random locations to real moments, enabling the ability to locate segments from random initialization. Once trained, MomentDiff could sample random temporal segments as initial guesses and iteratively refine them to generate an accurate temporal boundary. Different from discriminative works (e.g., based on learnable proposals or queries), MomentDiff with random initialized spans could resist the temporal location biases from datasets. To evaluate the influence of the temporal location biases, we propose two anti-bias datasets with location distribution shifts, named Charades-STA-Len and Charades-STA-Mom. The experimental results demonstrate that our efficient framework consistently outperforms state-of-the-art methods on three public benchmarks, and exhibits better generalization and robustness on the proposed anti-bias datasets. The code, model, and anti-bias evaluation datasets are available at https://github.com/IMCCretrieval/MomentDiff.Comment: 12 pages, 5 figure

Comparative metagenomic analysis of microbial community compositions and functions in cage aquaculture and its nearby non-aquaculture environments

In the context of burgeoning global aquaculture, its environmental repercussions, particularly in marine ecosystems, have gained significant attentions. Cage aquaculture, a prominent method, has been observed to significantly influence marine environments by discharging substantial amounts of organic materials and pollutants. It is also one of the important reasons for water eutrophication. This study investigated the impacts of cage aquaculture on microbial diversity and functional potential using metagenomics. Specifically, a comparison was made of the physicochemical indicators and microbial diversity between three grouper aquaculture cage nets in Lingshui Xincun Port and three nearby non-aquaculture area surface waters. We found that compared to non-aquaculture areas, the eutrophication indicators in aquaculture environments significantly increased, and the abundances of Vibrio and Pseudoalteromonas in aquaculture environments significantly rose. Additionally, microbial functional genes related to carbon, nitrogen, and sulfur metabolisms were also found to be significantly affected by aquaculture activities. The correlation analysis between microbial populations and environmental factors revealed that the abundances of most microbial taxa showed positive correlations with dissolved inorganic nitrogen, soluble reactive phosphorus, NH4+, and negative correlations with dissolved oxygen. Overall, this study elucidated the significant impacts of aquaculture-induced eutrophication on the diversity and functions of planktonic bacterial communities

Robust Adaptive Control for Coordinated Constrained Multiple Flexible Joint Manipulators with Hysteresis Loop

This paper focuses on the position/force tracking control problem for constrained multiple flexible joint manipulators system with nonlinear input of hysteresis loop. Firstly, the dynamic model is given in the task space and the input of hysteresis loop model is approximated by a differential equation. Secondly, considering the disturbance with unknown bounds, a robust adaptive control strategy based on the sliding mode which consists of constraint force error and position error is designed. The proposed approach can not only compensate the model error, external disturbance, and flexible parameter uncertainties, but also drive the closed-loop system variables to reach the sliding model surface. Then it can be proved that both position and constraint force errors can be guaranteed to converge to zero. Finally, the simulation results can verify the effectiveness of the proposed method

Solvents Induced ZnO Nanoparticles Aggregation Associated with Their Interfacial Effect on Organic Solar Cells

ZnO nanofilm as a cathode buffer layer has surface defects due to the aggregations of ZnO nanoparticles, leading to poor device performance of organic solar cells. In this paper, we report the ZnO nanoparticles aggregations in solution can be controlled by adjusting the solvents ratios (chloroform vs methanol). These aggregations could influence the morphology of ZnO film. Therefore, compact and homogeneous ZnO film can be obtained to help achieve a preferable power conversion efficiency of 8.54% in inverted organic solar cells. This improvement is attributed to the decreased leakage current and the increased electron-collecting efficiency as well as the improved interface contact with the active layer. In addition, we find the enhanced maximum exciton generation rate and exciton dissociation probability lead to the improvement of device performance due to the preferable ZnO dispersion. Compared to other methods of ZnO nanofilm fabrication, it is the more convenient, moderate, and effective to get a preferable ZnO buffer layer for high-efficiency organic solar cells

High-Performance Inverted Solar Cells Based on Blend Films of ZnO Naoparticles and TiO2 Nanorods as a Cathode Buffer Layer

We reported the favorable cathode buffer layer based on a blend of ZnO nanoparticles (NPs) and TiO2 nanorods (NRs) applied to inverted solar cells. In addition to the high optical transmittance, the resultant blend film gave a relatively dense film with lower roughness than that of the respective single-component film. This improved the interface contact between the buffer layer and photoactive layer and therefore reduced the contact resistance and leakage current. Moreover, the combination of NRs and NPs increased the efficiency of electron transport and collection by providing both a direct path for electron transport from TiO2 NRs and a large contact area between ZnO NPs and the active layer. Consequently, both the short-circuit current density (J(sc)) and fill factor (FF) in the device were improved, leading to an improvement of the device performance. The best power conversion efficiency (PCE) based on the blend film as the buffer layer reached 8.82%, which was preferable to those of a single ZnO NP film (7.76%) and a TiO2 NR-based device (7.66%)

Performance enhancement of inverted polymer solar cells with fullerene ester derivant-modified ZnO film as cathode buffer layer

In this paper, we reported that ZnO nanoparticles (NPs) film modified with C-60 pyrrolidine tris-acid ethyl ester (PyC60) was used as cathode buffer layer in inverted polymer solar cells. The resultant device with a blend of PTB7:PC71BM as photoactive materials exhibited an open-circuit voltage (V-OC) of 0.753 V, a short-circuit current (J(SC)) of 16.04 mA cm(-2), a fill factor (FF) of 72.5%, and an overall power conversion efficiency (PCE) of 8.76%. It was higher than the control devices based on sole ZnO NPs film or ZnO: PyC60 hybrid film as cathode buffer layer. It was found that the morphology improvement of ZnO/PyC60 film contributed to reducing series loss and interfacial charge recombination. In addition, it improved the interfacial contact with photoactive layer. The results increased electron injection and collection efficiency, and improved FF. (C) 2014 Elsevier B.V. All rights reserved

Layer‐by‐Layer Processed Organic Photovoltaic Cells Using Slot‐Die‐Coating Methods and Non‐halogenated Solvents under Ambient Conditions with PCE of 10%

Abstract Laboratory‐controlled conditions, spin‐coating method, and non‐ecofriendly halogenated solvents that have been employed for higher‐performance organic solar cells (OSCs) are not compatible with large‐scaled, roll‐to‐roll (R2R) manufacturing in ambient conditions. Slot‐die coating is a viable upscaling method, but the investigation of slot‐die‐coated OSCs is still rare, especially OSCs with all functional layers deposited with non‐halogenated solvents in air. Herein, all slot‐die coated devices are successfully manufactured by sequentially slot‐die coating the hole transport layer (PEDOT:PSS), the photoactive layers (PM6 and BTP‐4F‐12 (Y6‐C12)), and the electron transport layer (PFN‐Br). Because of solubility variation of photoactive components in non‐halogenated solvents (o‐Xylene and 2‐methyltetrahydrofuran (2‐MeTHF)), two bilayer‐processed photoactive films have been obtained via different solvent combinations (o‐Xylene/o‐Xylene for PM6 (o‐Xylene)/Y6C12 (o‐Xylene) and o‐Xylene/2‐MeTHF for PM6 (o‐Xylene)/Y6C12 (2‐MeTHF)). Different morphologies of bilayer‐processed photoactive films influence exciton dissociation and charge extraction properties of corresponding devices. Finally, the device hosting o‐Xylene/o‐Xylene processed photoactive film has a superior efficiency (10.6%) than the o‐Xylene/2‐MeTHF processed photoactive film‐based device (7.2%). Differently from device efficiency, the device based on o‐Xylene/2‐MeTHF processed photoactive film exhibits the preferable storage stability

Highly Efficient Organic Photovoltaics via Incorporation of Solution-Processed Cesium Stearate as the Cathode Interfacial Layer

Highly efficient organic solar cells were successfully demonstrated by incorporating a solution-processed cesium stearate between the photoactive layer and metal cathode as a novel cathode interfacial layer. The analysis of surface potential change indicated the existence of an interfacial dipole between the photoactive layer and metal electrode, which was responsible for the power conversion efficiency (PCE) enhancement of devices. The significant improvement in the device performance and the simple preparation method by solution processing suggested a promising and practical pathway to improve the efficiency of the organic solar cells